20000008 Ver 1_COMPLETE FILE_20000104

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??SF9 STATES
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
Sam Nunn Atlanta Federal Center
W17Z 4NDS/
MqR 401 CRolip
wgTE 0,9 2043
'-Q klrys
FCrjON
61 Forsyth Street, S.W.
Atlanta, Georgia 30303 - 8960
FEB 2 7 2001
Colonel Charles R. Alexander, Jr.
District Engineer
ATTN: Mr. Kevin Yates
U.S. Army Corps of Engineers
P.O. Box 1890
Wilmington, North Carolina 28402-1890
SUBJ: New Hanover County: Proposed Modification to Authorization for Mason Inlet
Action I.D. No. 199901052
Dear Colonel Alexander:
This is in reference to the above-listed modification request, dated January 17, 2003.
According to the information which was faxed to our office on February 19, 2003, New Hanover
County has requested a modification for the authorization to relocate Mason Inlet. Along with
the relocation of the inlet, the permit authorizes the renourishment of the southern end of Figure
Eight Island utilizing sand excavated during construction of the compensatory mitigation area.
The applicant has requested that. they be allowed to relocate up to 5,000 cubic yards of sand from
the mitigation area to the north end of Figure Eight Island (rather than the south end), to be
placed landward of emergency sandbags in front of fourteen houses on Comber Road and Inlet
Hook. The applicant would pump sand from the mitigation area onto the south'end of Figure
Eight Island, then transport 5,000 cubic yards of it along the ocean beach and dump it on the
north end of Figure Eight Island. Some sand would also be stockpiled for future placement
behind the same sandbags.
The U.S. Environmental Protection Agency (EPA), Region 4, Wetlands Regulatory
Section has reviewed the request, along with letters from the U.S. Fish and Wildlife Service
(Service) and the North Carolina Coastal Federation (NCCF). EPA shares the concerns of the
Service, that the proposed action area is well outside the original project impact area that was
considered under the permit. Also, the modification request does not include any consideration
of direct, secondary, or cumulative impacts of the proposal, and does not include any discussion
of alternatives or avoidance and minimization measures that may have been considered.
Based upon our concerns, we. cannot recommend approval of this modification request.
We recommend that the applicant submit a separate permit application for this activity, and
include information concerning alternatives considered, and avoidance and minimization of
impacts 0 aquatic resources.
2
Thank you for the opportunity to review this public notice. Should you have any
questions regarding our comments, please contact Kathy Matthews of my staff at 706-355-8780.
Sincerely,
Ronald J kulak, Chief
Wetlan egulatory Section
cc: Mason Inlet Relocation
Mr. Garland Pardue
Field Supervisor
U.S. Fish and Wildlife Service
P.O. Box 33726
Raleigh, North Carolina 27636-3726
Mr. Ron Sechler
National Marine Fisheries Service
Habitat Conservation Division
101 Pivers Island Road
Beaufort, North Carolina 28516-9722
Mr. John Dorney
Division of Water Quality
North Carolina Department of Environment
and Natural Resources
1650 Mail Service Center
Raleigh, North Carolina 27699-1650
Mr. Doug Huggett
Division of Coastal Management
North Carolina Department of Environment
and Natural Resources
1638 Mail Service Center
Raleigh, North Carolina 27699-1638
Mr. Bob Stroud, District Manager
Division of Coastal Management
North Carolina Department of Environment
and Natural Resources
127 Cardinal Drive Extension
Wilmington, North Carolina 28405-3845
Mr. Charles R. Fullwood, Executive
Director
North Carolina Wildlife Resources
Commission
1701 Mail Service Center
Raleigh, North Carolina 27699-1701
f
AIM
APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA, INC.
April 23, 2002
Mr. John Domey
Division of Water Quality
1621 Mail Service Center
Raleigh, NC 27699-1621
Re: Certificate of Completion
Mason Inlet Relocation Project
Dear Mr. Dorney:

Enclosed is the executed Certificate of Completion for the Mason Inlet Relocation Project.
I have attached a copy of DWQ Certificate no. 3274, issued to New Hanover County and
dated June 27, 2001.
Sincerely,
Karyn t s (o n, P. E.
Vice President
Enclosure
cc: Keith Harris, USACE
Doug Huggett, DCM
Joann Steinhuis, DWQ
Dave Weaver, New Hanover Co.
Greg Thompson, New Hanover Co.
Steve Morrison, Land Management Group Inc.
201 North Front Street, Suite 508
Wilmington, North Carolina 28401
TEL [phone] FAX [phone]
Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
DWQ Project No.: 000008 County: New Hanover
Applicant: _ New Hanover County
Date of Issuance of 401 Water Quality Certification: June 27.. 2001
Certificate of Completion
Upon completion of all work approved within the 401 Water Quality Certification or
applicable Buffer Rules, and any subsequent modifications, the applicant is required to
return this certificate to the 401/Wetlands Unit, North Carolina Division of Water Quality,
1621 Mail Service Center, Raleigh, NC, 27699-1621.This form may be returned to DWQ by
the applicant, the applicant's authorized agent, or the project engineer.lt is not necessary to
send certificates from all of these.
Applicant's Certification
I, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: f Date:
Agent's Certification
xaryn M_ Erickson, P.E. , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be 'It within substantial compliance and intent of the 401
Water Quality Certification and B ff r Rules, the approved plans and specifi ations, and
other support- at ials.
Signature: Date:
If this project was designed by a Certified Professional
I, Ka r?Zn M. Fr i rkSnn , P.R. , as a duly registered Professional P . E .
(i.e., Engineer, Landscape Architect., Surveyor, ect.) in the State of North Carolina, having
been authorized to observe (periodically, weekly, full time) the construction of the project,
for the Permittee hereby state that, to the best of my abilities, due care and diligence was
used in the observation of the construction such that the construction was observed to be
built within substanti ompliance and intent of the 401 Water Quality Certification and
Buffer Ru es, a ap ed pans and specifications, and other supporting r'I? erial .
Signatu Registration No. NC 022459 Date `f Z Z ate.,
AA .
0
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]

Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
NORTH CAROLINA 401 WATER QUALITY CERTIFICATION
THIS CERTIFICATION is issued in conformity with the requirements of Section 401 Public
Laws 92-500 and 95-217 of the United States and subject to the North Carolina Division of
Water Quality (DWQ) Regulations in 15 NCAC 2H, Section .0500. It is issued to New Hanover
County resulting in 1.9 acres of wetland impact 49 acres of open water dredging and 41 acres of
open water fill in New Hanover County pursuant to an application filed on the 4 day of June,
2000 with the final EA/FONSI and letter dated January 8, 2001 from Applied Technology and
Management of N.C., Inc. to relocate Mason's Inlet.
The application provides adequate assurance that the discharge of fill material into the
waters of the Atlantic Ocean (Mason's Inlet) and Mason's Creek in conjunction with the
proposed development will not result in a violation of applicable Water Quality Standards and
discharge guidelines. Therefore, the State of North Carolina certifies that this activity will not
violate the applicable portions of Sections 301, 302, 303, 306, 307 of PL 92-500 and PL 95-217
if conducted in accordance with the application and conditions hereinafterset forth.
This approval is only valid for the purpose and design that you submitted in your
application, as described in the Public Notice. If you change your project, you must notify us and
send us a new application for a new certification. If the property is sold, the new owner must be
given a copy of the Certification and approval letter and is thereby responsible for complying with
all conditions. If total wetland fills for this project (now or in the future) exceed one acre or total
perennial stream impact exceeds 150 feet, compensatory mitigation may be required as
described in 15A NCAC 2H .0506 (h) (6) and (7). For this approval to be valid, you must follow
the conditions listed below. In addition, you should get any other federal, state or local permits
before you go ahead with your project including (but not limited to) Sediment and Erosion
control, Coastal Stormwater, Non-discharge and Water Supply watershed regulations.
Condition(s) of Certification:
1. Appropriate sediment and erosion control practices which equal or exceed those outlined in the
most recent version of two manuals, either the "North Carolina Sediment and Erosion Control
Planning and Design Manual" or the "North Carolina Surface Mining Manual" (available from the
Division of Land Resources in the DEHNR Regional or Central Offices). The control practices
shall be utilized to prevent exceedances of the appropriate turbidity water quality standard (50
NTUs in all fresh water streams and rivers not designated as trout waters; 25 NTUs in all lakes
and reservoirs, and all saltwater classes; and 10 NTUs in trout waters);
2. All sediment and erosion control measures placed in wetlands or waters shall be removed and
the natural grade restored after the Division of Land Resources has released the project;
3. Measures shall be taken to prevent live or fresh concrete from coming into contact with
waters of the state until the concrete has hardened;
4. Should waste or borrow sites be located in wetlands or other waters, compensatory mitigation
will be required since it is a direct impact from road construction activities,
5. Compensatory mitigation shall be done as outlined in the final EA/FONSI with the following
additions:
a) Biological monitoring shall be for three (3) transects rather than the two proposed,
b) Biological monitoring shall be for five years. Three copies of annual reports shall be sent to
DWQ for review and comment and recommended modifications shall be implemented to
ensure success,

Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]

Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
6. Applicant shall submit within four mouths for written DWQ approval a plan to monitor marshes
adjacent to Mason's Creek. This plan shall included measure, to compare the predicted water
velocities to help understand and compensate for any observed impacts to marshes. If this
monitoring reveals an additional loss of wetlands in this area, then additional compensatory
wetland mitigation will be required.
7. All other conditions of General Certification #3274 are hereby incorporated by reference.
Violations of any condition herein set forth shall result in revocation of this Certification and
may result in criminal and/or civil penalties. This Certification shall become null and void unless
the above conditions are made conditions of the Federal 404 and/or coastal Area Management
Act Permit. This Certification shall expire upon expiration of the 404 or CAMA permit.
If this Certification is unacceptable to you have the right to an adjudicatory hearing upon
written request within sixty (60) days following receipt of this Certification. This request must be
in the form of a written petition conforming to Chapter 150B of the North Carolina General
Statutes and filed with the Office of Administrative Hearings, P.O. Box 27447, Raleigh, N.C.
27611-7447. If modifications are made to an original Certification, you have the right to an
adjudicatory hearing on the modifications upon written request within sixty (60) days following
receipt of the Certification. Unless such demands are made, this Certification shall be final and
binding.
This the 27TH day of June, 2001
DIVISION OF WATER QUALITY
tevens
:.
R
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]

Jy? > r
2 t??y' ? ?? S?P
?r
r 'ell P
June 27, 2001
Mr. Greg Thompson
New Hanover County
414 Chestnut Street
Wilmington, NC 28401
Dear Mr. Thompson:
Re: Revised Certification Pursuant to Section 401 of the Federal Clean Water Act,
Proposed Mason's Inlet relocation and associated dredging
WQC Project #000008
New Hanover County
Attached hereto is a copy of the revised Certification No.3274 issued to New Hanover County
dated June 27, 2000. This Certification replaces one issued to you on April 30, 2001.
If we can be of further assistance, do not hesitate to contact us.
Attachments
i
FTcel
,
teven'
cc: Corps of Engineers Wilmington Field Office
Wilmington DWQ Regional Office
Doug Huggett, Division of Coastal Management
File Copy
Central Files
Karyn Erickson Applied Technology & Management of N.C., Inc. 201 Front Street, Ste 201
Wilmington, NC 28402
Steve Morrison; Land Management Group, Post Office Box 2522, Wilmington, NC 28402
.
1111111111111-1
DEt
Division of Water Quality
Wetlands/401 Unit: [phone]
Fax: [phone]
Michael F. Easley
Governor -
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
1621 Mail Service Center Raleigh, NC 27699-1621
I
Department of Sherri Evans-Stan;, n, ?lcfir
Environment and Nai?'ra! k.S
NORTH CAROLINA 40 Kerr T. Si I
Division of water Q
CERTIFIC
WATER Q UALITY CERTIFICATION
T HIS Laws 92.500 ATION is issued in conformity Water Quality and 95-217 Of the with the re
(DWQ) Re United States and sub' qut
County resultin gulations in 15 NCAC 2H lect to the rements of Section 401 Pub
acres
050 0' It w
lic water fill nt New of wetland impact 49 acres Of open water en is issued to Ne acres of
of
Management the final E'vFONSI and Y Pursuant to an a dredgin Hanover
of N•C• letter dated January 8, filed g and 41 acres g 2ca on the 4 da
Inc, to relocate anuary
Bement The a Mason s inlet. from Applied TeChnolo Of June
waters ppltcation provides ode gy and
of the Atlantic quote assurance
proposed development Ocean (Mason's that the discharge
discharge g will not result in Inlet) and Mason's of fill
uidelines, a violation of a Creek in material into the
the a Therefore
violate , the pplicable conjunction
if conducted Pn Itcabie Portions of Sections to of North C Water Qualit with the
accordance Carolina certifies that thi s Standards and
with the applicati3 1, on nd Conk' 306, 307 activit
This of PL 92_ Y will not
approval ttons hereinafter set for Ottand PL 95'217
application, as described nl vad for
send us a the purpose the Public Notice. If and design that
given a co new application for a new ce You chan YOU
submitted
all conditions of the Certification and certification. If the property iproject, You must to Your
ge Your approval letter and is
thereby s SOId, the notify us and
If total wetland fills for this
perennial strew y responsible owner must be
described in 15 m impact exceeds 150 project (now or in the future) onsible for com
the conditions I'stedcAC 2H 0506 feet, compensatory exceed one p acre or e or with
(h) (6) and mitigation total
before you o ahead below In addition (7)• For this may be re
control, Coa with You should approval to be valid quired as
;I
sl Stormwater Your Pr°iect including get any other federal ' YOU must follow
Non-
on-(but not limited to) 'state or local
Conditions discharge and Water S Sediment permits
() of Certification: apply watershed re gulations.nd Erosion
1. Appropriate sediment and
most recent version erosion control
Planning and ersi of two manuals practices which e
Division of Design Manual" or "' either the "North equal or exceed those
Land Resources the North C Carolina Sedi Outlined in the
shall be utilized to to the DEHNR RefOltna Surface Minin ment and Erosion
,, ntrol
NTUs in all fresh prevent exceedances g1Onal or g Manual co
water strew of the a Central Offices). Theacontrol e from the
and reservoirs, and all saltwater c asseSers
not PPr°priate turbidity water quay Practices
2 All sediment and erosion , and 10 NTUs in trout trout waters); 25 y standard (); NTUs in all lakes
es
the natural grade restored control measures
after the Division of Placed in wetlands or
3• Measures shall be Resources has waters shall be remove
waters of the state until taken the to prevent live or fresh concrete from coming into contact
waste or borro with
Will be re w sites be located in wetlands
quired since
it is a direct im Or other
Compensatory 5• pact from road construction waters, compensatory
mitigation shah be activities;
?' mitigation
tigation
additions: done as outlined in the
a) Biological monitoring final EA/FO
b) Biological monftoting shall be for three NSI with the following
9 shall be for five Years. I Threes rather than the two prop OSed,
' ended modifications reports shall be sent to
hall be implemented to
N
Wetlands/4oi Unit: (91g) 733-178 fi ;vision of
Water Quality 1621 Mail Service Center Raleigh, NC 27699.1621
i

Michael F. Easley
y. Governor
Sherri Evans-Stanton, Actin Secrets
;. n'.. y
>
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
6. Applicant shall submit within four mouths for written DWQ approval a plan to monitor marshes
adjacent to Mason's Creek. This plan shall included measure, to compare the predicted water
velocities to help understand and compensate for any observed impacts to marshes. If this
monitoring reveals an additional loss of wetlands in this area, then additional compensatory
wetland mitigation will be required.
7. All other conditions of General Certification #3274 are hereby incorporated by reference
Violations of any condition herein set forth shall result in revocation of this Certification and
may result in criminal and/or civil penalties. This Certification shall become null and void unless
the above conditions are made conditions of the Federal 404 and/or coastal Area Management
Act Permit. This Certification shall expire upon expiration of the 404 or CAMA permit.
If this Certification is unacceptable to you have the right to an adjudicatory hearing upon
written request within sixty (60) days following receipt of this Certification. This request must be
in the form of a written petition conforming to Chapter 150B of the North Carolina General
Statutes and filed with the Office of Administrative Hearings, P.O. Box 27447, Raleigh, N.C.
27611-7447. If modifications are made to an original. Certification, you have the right to an
adjudicatory hearing on the modifications upon written request within sixty (60) days following
receipt of the Certification. Unless such demands are made, this Certification shall be final and
binding. s
This the 27TH day of June, 2001
DIVISION OF WATER QUALITY
e r tevens
Xlw.
N E'
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
->
DWQ Project No.: County:
Applicant:
Date of Issuance of 401 Water Quality Certification:
Certificate of Completion
Upon completion of all work approved within the 401 Water Quality Certification or
applicable Buffer Rules, and any subsequent modifications, the applicant is required to
return this certificate to the 401/Wetlands Unit, North Carolina Division of Water Quality,
1621 Mail Service Center, Raleigh, NC, 27699-1621.This form may be returned to DWQ by
the applicant, the applicant's authorized agent, or the project engineer.lt is not necessary to
send certificates from all of these.
Applicant's Certification
I, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: Date:
Agent's Certification
I, w , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: Date:
If this project was designed by a Certified Professional
I, . , as a duly registered Professional
(i.e., Engineer, Landscape Architect, Surveyor, ect.) in the State of North Carolina, having
been authorized to observe (periodically, weekly, full time) the construction of the project,
for the Permittee hereby state that, to the best of my abilities, due care and diligence was
used in the observation of the construction such that the construction was observed to be
built within substantial compliance and intent of the 401 Water Quality Certification and
Buffer Rules, the approved plans and specifications, and other supporting materials.
Signature - Registration No. ` - Date - -
[?EI?
Michael F. Easley
Governor -
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
5WUA, J 6C.
&n4wnmei7LLAiL gw Ofiee Ax 2,522
Vd6my&n,, A,owA %iitdma 28402
9d 970-452-0007
g Aid..
°N! ? .?ottioon
John Dorney
Division of Water Quality
Wetlands/401 Unit
1621 Mail Service Center
Raleigh, N.C. 27699-1621
tt wile 74
6/13/01 I T..y A.'h ep. yam
3805 V#*4& 1k . wnm
VdMuV&a./1'F8 28403
Re: Mason Inlet Relocation Project, 401 Water Quality Certification No. 3274
Dear John,
We are in receipt of the Water Quality Certification No. 3274 issued on April 30th 2001
for the Mason Inlet Relocation Project. The Certification incorrectly stated that 2.9 acres
of wetland are to be impacted. The minimized final dredging dimensions within Mason
Creek were reduced from a 170' width to a 140' width, reducing the impact from 2.9
acres to 1.9 acres of wetland. This is reflected in the April, 2000 Environmental
Assessment and December, 2000 Wetland Mitigation Plan.
Please modify the Certification to clarify this reduced area of wetland impact for receipt
by the applicant and those copied in the original approval. Thank you for your assistance.
Sincerely,
Steve Morrison
Environmental Consultant
Cc:
Greg Thompson, New Hanover County
Joanne Steenhuis, Wilmington DWQ Regional Office
Doug Huggett, Division of Coastal Management
Jeff Richter, Corps of Engineers
Karyn Erickson, Applied Technology & Management of N.C., Inc.
- C14

X33 Z5?7a
Michael F. Easley
Governor -
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
April 30, 2001
Mr. Greg Thompson
New Hanover County
414 Chestnut Street
Wilmington, NC 28401
Dear Mr. Thompson:
Re: Certification Pursuant to Section 401 of the Federal Clean Water Act,
Proposed Mason's Inlet relocation and associated dredging
WQC Project #000008
New Hanover County
Attached hereto is a copy of Certification No.3274 issued to New Hanover County dated
April 30, 2000.
If we can be of further assistance, do not hesitate to contact us.
Y Sin erely,
.Stevens
Attachments
cc: Corps of Engineers Wilmington Field Office
Wilmington DWQ Regional Office
Doug Huggett, Division of Coastal Management
File Copy
Central Files
Karyn Erickson Applied Technology & Management of N.C., Inc.

VN
nix
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
by
Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Secretary
fi a Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
NORTH CAROLINA 401 WATER QUALITY CERTIFICATION
THIS CERTIFICATION is issued in conformity with the requirements of Section 401 Public
Laws 92-500 and 95-217 of the United States and subject to the North Carolina Division of
Water Quality (DWQ) Regulations in 15 NCAC 2H, Section .0500. It is issued to New Hanover
County resulting in 2.9 acres of wetland impact, 49 acres of open water dredging and 41 acres
of open water fill in New Hanover County pursuant to an application filed on the 4 day of June,
2000 and with the final EA/FONSI and letter dated January 8, 2001 from Applied Technology
and Management of N.C., Inc. to relocate Mason's Inlet.
The application provides adequate assurance that the discharge of fill material into the
waters of the Atlantic Ocean (Mason's Inlet) and Mason's Creek in conjunction with the
proposed development will not result in a violation of applicable Water Quality Standards and
discharge guidelines. Therefore, the State of North Carolina certifies that this activity will not
violate the applicable portions of Sections 301, 302, 303, 306, 307 of PL 92-500 and PL 95-217
if conducted in accordance with the application and conditions hereinafter set forth.
This approval is only valid for the purpose and design that you submitted in your
application, as described in the Public Notice. If you change your project, you must notify us and
send us a new application for a new certification. If the property is sold, the new owner must be
given a copy of the Certification and approval letter and is thereby responsible for complying with
all conditions. If total wetland fills for this project (now or in the future) exceed one acre or total
perennial stream impact exceeds 150 feet, compensatory mitigation may be required as
described in 15A NCAC 2H .0506 (h) (6) and (7). For this approval to be valid, you must follow
the conditions listed below. In addition, you should get any other federal, state or local permits
before you go ahead with your project including (but not limited to) Sediment and Erosion
control, Coastal Stormwater, Non-discharge and Water Supply watershed regulations.
Condition(s) of Certification:
Appropriate sediment and erosion control practices which equal or exceed those outlined in the
most recent version of two manuals, either the "North Carolina Sediment and Erosion Control
Planning and Design Manual" or the "North Carolina Surface Mining Manual" (available from the
Division of Land Resources in the DEHNR Regional or Central Offices). The control practices
shall be utilized to prevent exceedances of the appropriate turbidity water quality standard (50
NTUs in all fresh water streams and rivers not designated as trout waters; 25 NTUs in all lakes
and reservoirs, and all saltwater classes; and 10 NTUs in trout waters);
2. All sediment and erosion control measures placed in wetlands or waters shall be removed and
the natural grade restored after the Division of Land Resources has released the project;
3.. -Measures shall be taken to prevent live or fresh concrete from coming into contact with - - - - - - - - -- -- - - - --
waters of the state until the concrete has hardened;
4. Should waste or borrow sites be located in wetlands or other waters, compensatory mitigation
will be required since it is a direct impact from road construction activities;
5. Compensatory mitigation shall be done as outlined in the final EA/FONSI with the following
additions:
a) Biological monitoring shall be for three (3) transects rather than the two proposed,
b) Biological monitoring shall be for five years. Three copies of annual reports shall be sent to
DWQ for review and comment and recommended modifications shall be implemented to
ensure success,
R=x
?it..L?tLaK;
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]

NORTH CAROLINA 401 WATER QUALITY CERTIFICATION
THIS CERTIFICATION is issued in conformity with the requirements of Section 401 Public
Laws 92-500 and 95-217 of the United States and subject to the North Carolina Division of
Water Quality (DWQ) Regulations in 15 NCAC 2H, Section .0500. It is issued to New Hanover
County resulting in 2.9 acres of wetland impact, 49 acres of open water dredging and 41 acres
of open water fill in New Hanover County pursuant to an application filed on the 4 day of June,
2000 and with the final EA/FONSI and letter dated January 8, 2001 from Applied Technology
and Management of N.C., Inc. to relocate Mason's Inlet.
The application provides adequate assurance that the discharge of fill material into the
waters of the Atlantic Ocean (Mason's Inlet) and Mason's Creek in conjunction with the
proposed development will not result in a violation of applicable Water Quality Standards and
discharge guidelines. Therefore, the State of North Carolina certifies that this activity will not
violate the applicable portions of Sections 301, 302, 303, 306, 307 of PL 92-500 and PL 95-217
if conducted in accordance with the application and conditions hereinafter set forth.
This approval is only valid for the purpose and design that you submitted in your
application, as described in the Public Notice. If you change your project, you must notify us and
send us a new application for a new certification. If the property is sold, the new owner must be
given a copy of the Certification and approval letter and is thereby responsible for complying with
all conditions. If total wetland fills for this project (now or in the future) exceed one acre or total
perennial stream impact exceeds 150 feet, compensatory mitigation may be required as
described in 15A NCAC 2H .0506 (h) (6) and (7). For this approval to be valid, you must follow
the conditions listed below. In addition, you should get any other federal, state or local permits
before you go ahead with your project including (but not limited to) Sediment and Erosion
control, Coastal Stormwater, Non-discharge and Water Supply watershed regulations.
Condition(s) of Certification:
Appropriate sediment and erosion control practices which equal or exceed those outlined in the
most recent version of two manuals, either the "North Carolina Sediment and Erosion Control
Planning and Design Manual" or the "North Carolina Surface Mining Manual" (available from the
Division of Land Resources in the DEHNR Regional or Central Offices). The control practices
shall be utilized to prevent exceedances of the appropriate turbidity water quality standard (50
NTUs in all fresh water streams and rivers not designated as trout waters; 25 NTUs in all lakes
and reservoirs, and all saltwater classes; and 10 NTUs in trout waters);
All sediment and erosion control measures placed in wetlands or waters shall be removed and
the natural grade restored after the Division of Land Resources has released the project;
3. --Measures- shall be taken to prevent live or fresh concrete from coming into contact with - - - - - - - - -- - - - - -
waters of the state until the concrete has hardened;
4.. Should waste or borrow sites be located in wetlands or other waters, compensatory mitigation
will be required since it is a direct impact from road construction activities;
5. Compensatory mitigation shall be done as outlined in the final EA/FONSI with the following
additions:
a) Biological monitoring shall be for three (3) transects rather than the two proposed, ,
b) Biological monitoring shall be for five years. Three copies of annual reports shall be sent to
DWQ for review and comment and recommended modifications shall be implemented to
ensure success,
AN
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Sedretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
'' 3 Michael F. Easley
Governor -
Sherri Evans-Stanton, Acting Secretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
6. Applicant shall submit within four months of the issuance of the CAMA Permit for written DWQ
approval a plan to monitor salt marshes adjacent to Mason's Creek. This plan shall included
measure to compare the predicted water velocities to help understand and compensate for any
observed impacts to marshes. If this monitoring reveals an additional loss of wetlands in this
area, then additional compensatory wetland mitigation will be required. This plan will require
additional written DWQ approval.
7. All other conditions of General Certification #3274 are hereby incorporated by reference.
Violations of any condition herein set forth shall result in revocation of this Certification and
may result in criminal and/or civil penalties. This Certification shall become null and void unless
the above conditions are made conditions of the Federal 404 and/or coastal Area Management
Act Permit. This Certification shall expire upon expiration of the 404 or CAMA permit.
If this Certification is unacceptable to you have the right to an adjudicatory hearing upon
written request within sixty (60) days following receipt of this Certification. This request must be in
the form of a written petition conforming to Chapter 150B of the North Carolina General Statutes
and filed with the Office of Administrative Hearings, P.O. Box 27447, Raleigh, N.C. 27611-7447.
If modifications are made to an original Certification, you have the right to an adjudicatory hearing
on the modifications upon written request within sixty (60) days following receipt of the
Certification. Unless such demands are made, this Certification shall be final and binding.
This the 30th day of April 2000
DIVISION nF WATFR nl IAI ITY
,"A'
L71w;'r
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: '[phone]
Fax: [phone]
Michael F. Easley
Governor -
Sherri Evans-Stanton, Acting SP.cretary'
Department of Environment and Natural Resources.
Kerr T. Stevens
Division of Water Quality
DWQ Project No.: County:
Applicant:
Date of Issuance of 401 Water Quality Certification:
Certificate of Completion
Upon completion of all work approved within the 401 Water Quality Certification or
applicable Buffer Rules, and any subsequent modifications, the applicant is required to
return this certificate to the 401/Wetlands Unit, North Carolina Division of Water Quality,
1621 Mail Service Center, Raleigh, NC, 27699-1621.This form may be returned to DWQ by
the applicant, the applicant's authorized agent, or the project engineer.lt is not necessary to
send certificates from all of these.
Applicant's Certification
1, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: Date:
Agent's Certification
I, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: Date:
if this project was designed by a Certified Professional
I, , as a duly registered Professional
(i.e., Engineer, Landscape Architect, Surveyor, ect.) in the State of North Carolina, having
been authorized to observe (periodically, weekly, full time) the construction of the project,
for the Permittee hereby state that, to the best of my abilities, due care and diligence was
used in the observation of the construction such that the construction was observed to be
built within substantial compliance and intent of the 401 Water Quality Certification and
Buffer Rules, the approved plans and specifications, and other supporting materials.
Signature Registration No. Date
'QUO

Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
'R
Michael F. Easley
Governor
Sherri Evans-Stanton, Acting Sgcretary
Department of Environment and Natural Resources
Kerr T. Stevens
Division of Water Quality
DWQ Project No.: County:
Applicant:
Date of Issuance of 401 Water Quality Certification:
Certificate of Completion
Upon completion of all work approved within the 401 Water Quality Certification or
applicable Buffer Rules, and any subsequent modifications, the applicant is required to
return this certificate to the 401/Wetlands Unit, North Carolina Division of Water Quality,
1621 Mail Service Center, Raleigh, NC, 27699-1621.This form may be returned to DWQ by
the applicant, the applicant's authorized agent, or the project engineer.lt is not necessary to
send certificates from all of these.
Applicant's Certification
1, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: Date:
Agent's Certification
I, , hereby state that, to the best of my abilities,
due care and diligence was used in the observation of the construction such that the
construction was observed to be built within substantial compliance and intent of the 401
Water Quality Certification and Buffer Rules, the approved plans and specifications, and
other supporting materials.
Signature: _ Date:
If this project was designed by a Certified Professional
I, , as a duly registered Professional
(i.e., Engineer, Landscape Architect, Surveyor, ect.) in the State of North Carolina, having
been authorized to observe (periodically, weekly, full time) the construction of the project,
for the Permittee hereby state that, to the best of my abilities, due care and diligence was
used in the observation of the construction such that the construction was observed to be
built within substantial compliance and intent of the 401 Water Quality Certification and
Buffer Rules, the approved plans and specifications, and other supporting materials.
Signature Registration No. Date
--- - ------------ ----= -`---.
ALA'
Nt?L?EAr
Division of Water Quality 1621 Mail Service Center Raleigh, NC 27699-1621
Wetlands/401 Unit: [phone]
Fax: [phone]
State of North Carolina
Department of Environment
and,Natural Resources
Wilmington Regional Office
Division of Coastal Management
James B. Hunt, Jr., Governor
Bill Holman, Secretary
Donna D. Moffitt, Director
December 20, 1999
MEMORANDUM:
TO: Mr. John R. Dorney, NCDENR
Division of Water Quality
4401 Reedy Creek Road
Raleigh, NC 27611-7687
FROM: Doug Huggett
Major Permits Processing Coordinator
14 WNWA
?....•-.?.? • f
NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES

SUBJECT: CAMA/DREDGE & FILL Permit Application Review
Applicant: New Hanover County (c/o: Greg Thompson)
Project Location: Mason Inlet, between Figure 8 Island & Wrightsville Beach, NC, New Hanover
County
Proposed Project: To relocate Mason Inlet 3,000 to the north of its present location and to dredge the
shoaled Mason Creek to F rovide a sufficient tidal prism to maintain locational
stability of the new inlet channel.
Please indicate below your agency's position or viewpoint on the proposed project and return this form
by January 25, 2000. If you have any questions regarding the proposed project, please contact
E.F. Brooks at extension 247. When appropriate, in-depth comments with supporting data is requested.
REPLY: This agency has no objection to the project as proposed.
This agency has no comment on the proposed project.
v This agency approves of the project only if the recommended changes are
incorporated. See attached.
This agency objects to the project for reasons described in the attached comments.
SIGNED DATE 3? 0 J
127 Car mal Dr. Ext., Wilmington, North Carolina 2840° Telephone [phone] FAX [phone]

DIVISION OF COASTAL MANAGEMENT
FIELD INVESTIGATION REPORT.
1. APPLICANT' S NAME: New Hanover County

2. LOCATION OF PROJECT SITE: Mason Inlet, between Figure 8 Island and Wrightsville
Beach, in New Hanover Co.
Photo Index - IM: 11-224 & 2261295:24-291 1989:5 176-21 & 22 1984: 19-283 & 284
State Plane Coordinates - X:2371651 Y: 182526
3. INVESTIGATION TYPE: CAMA/D&F
4. INVESTIGATIVE PROCEDURE: Dates of Site Visit - 7//29/99, 10/7/99, 10/28/99
Was Applicant Present - Yes (Applicant or agent)
5. PROCESSING PROCEDURE: Application Received - 11/1/99 (EA rec. in Raleigh; 6
Office - Wilmington
6. SITE DESCRIPTION:
(A) Local Land Use Plan - New Hanover Co.
Land Classification From LUP - Conservation
(B) AEC(s) Involved: EW,PT,OH,CW.
(C) Water Dependent: Yes
(D) Intended Use: Public/Private
(E) Wastewater Treatment: Existing - N/A
Planned - None
(F) Type of Structures: Existing - None
Planned - None (Inlet relocation project)
(G) Estimated Annual Rate of Erosion: N/A
Source - N/A
7. HABITAT DESCRIPTION: [AREA]
MPT)rTPT) PTT T RTl n O'D
(A) Vegetated Wetlands 126,324 sqft.
(2.9 acres)
(B) Non-Vegetated Wetlands 2,134,440 sa. 1,800,000 sq.
Open water ft. (49 acre ft, (41 acre4

(C) Other - Beach Renourishment 2,550,000 sq.
ft (58.5 acres)
WI lotai Area 1»sturbecl: 1J4.3 acres
(E) Primary Nursery Area: No
(F) Water Classification: SA-ORW Open: CLOSED
8. PROJECT SUMMARY: The applicants propose to relocate Mason Inlet 3,000 to the north of
New Hanover Co./Mason Inlet Relocation Project
Page 2
its present location and to dredge the shoaled Mason Creek to provide a sufficient tidal prism to maintain
locational stability of the new inlet channel.
9. PROJECT DESCRIPTION
Mason Inlet is located between Wrightsville Beach (south) and Figure 8 Island (north), in New Hanover
County. The inlet provides one of the connections to the Atlantic Ocean for Middle Sound, which
includes an approximately 13 mile long estuary between the beaches and the mainland, between
Masonboro Inlet (south) and Little Topsail Inlet (north). Rich Inlet provides a fourth ocean outlet for
Middle Sound. Middle Sound encompasses broad expanses of Smooth Cordgrass (Spanina alterniflora)
marsh, tidal flats, and creeks, between the barrier islands and the mainland, including the following major
tidal creeks: Howe, Pages, Futch, Mason, Banks Channel (behind south Figure 8 Island), Nixon and
Green Channels, as well as, the Atlantic Intracoastal Waterway, between Wrightsville and Topsail
beaches. The project area involves an approximately 90 acre area of Mason Inlet and Mason Creek.
Over the past five decades, Mason Inlet has migrated approximately 6,500 feet south to it's present
location. Since 1980 the inlet throat has moved approximately 3500 feet to the south, and currently
presents an erosion threat to the development on the northern end of Wrightsville Beach, including the
multi-story Shell Island Resort complex, the terminus of North Lumina Avenue, as well as numerous
single-family and multi-family residential structures located to the south of the resort. A public beach
accessway, bath house, parking lot, as well as, the northern terminus of North Lumina Avenue have
already been lost to erosion. In 1997, authorization was obtained by the Shell Island Homeowners
Association to install a temporary sand-filled geotextile tube revetment along the north and a portion of
the east sides of the Shell Island Resort complex. The Town of Wrightsville Beach also obtained
emergency permits to install conventional sandbags to temporarily protect the end of North Lumina
Avenue. The throat of Mason Inlet is currently located at the base of these temporary structures.
Historically, Mason Creek was one of the two primary channels between Mason Inlet and the AIWW.
Mason Creek provides an east-west channel orientation to the inlet and the north-south orientation of
Banks Channel, behind Figure 8 Island, is the inlet's other primary channel. Extensive shoaling along the
entire length (approx. 4,500 ft.) of Mason Creek has significantly reduced it's contribution to the
hydraulic volume of the inlet. Once over 400 feet wide, the open water area of the creek has been
narrowed in some areas to less than 100 feet in width, due to shoal accretion and subsequent emergent
stands of Smooth Cordgrass (Spartina alterniflora) vegetation. At low water, the creek is not navigable,
however, with local knowledge of the narrowed channel, the creek is passable at mid to high water in
small, shallow draft watercraft. In contrast, the channelization of Banks Channel in the 1960s, by the
early developers of Figure 8 Island, and the continued maintenance of that navigation channel to the
present, by the Figure 8 Island Property Owners Association (State Permit # 26-92) have kept the 13,570
ft. long, 125 ft. wide channel open to a depth of -9 feet, at mean low water. Excavated sediments from
the maintenance dredging projects are utilized to renourish the chronically eroded beach front of the
southern half of Figure 8 Island. At present, Banks Channel is the primary hydrologic component of the
tidal exchange for Mason Inlet.

New Hanover Co./Mason Inlet Relocation Project
Page 3
In the project area, the waters of Mason Creek are classified as SA-ORW, by the NC Division of Water
Quality, and they are OPEN to the harvest of shellfish. Although the saltmarsh on either side of the
project area are designated as Primary Nursery Area (PNA), by the NC Division of Marine Fisheries,
the waters of Mason Inlet and Mason Creek are not included in the surrounding PNA designation.
The applicants propose to relocate Mason Inlet 3,000 to the north of its present location and to dredge
the shoaled Mason Creek to provide a sufficient tidal prism to maintain locational stability of the new inlet
channel. The concept of the relocation of Mason Inlet began in the fall of 1996, as a joint venture of the
Shell Island Resort Homeowners Association and the Figure 8 Beach Homeowners Association, to address
the erosion problems of Shell Island Resort and the beach renourishment needs of Figure 8 Island. A draft
Environmental Assessment was prepared for preliminary review in connection with the proposed project,
however, when the project sponsors were unable to obtain the necessary rights from the property owners
to allow the inlet relocation, plans to submit a permit application were suspended. Direct hits from five
(5) major hurricanes over the last four years have exacerbated the erosion threat to both Figure 8 Island
and the north end of Wrightsville Beach. The current application is submitted with New Hanover County
as the project's sponsor. Their legal agreement with the property owners to allow the project is included
in this application. Figure 8 Beach Homeowers Association and Shell Island Resort Homeowners
Association, as well as, other property owners that would benefit from the inlet relocation, remain as
active parties in the project. Benefiting property owners will repay the County's loan that would provide
funding for the project, and Figure 8 Beach HOA would purchase excavated sediments for beach
renourishment. An Environmental Assesment (EA) for the project has been prepared by Applied
Technology and Management of North Carolina, Inc. and Land Management Group, Inc. and is being
reviewed concurrently with this application by State and federal agencies through the Clearing House
review process, as required by the State Environmental Policy Act. Detailed information with respect to
the proposed project's purpose, existing environment, need for action, alternatives analysis, environmental
consequences, and mitigative measures are presented in this document, as well as, the hydrodynamic
modeling data used to design the project's proposed dimensions. The EA's prefered alternative is the
proposed project in this application.
The proposed new inlet channel would be dredged through the southern end of Figure 8 Island, within
the inlet corridor, approximately 3,000 feet north of its present location. The inlet channel would be 2100
feet long, 500 feet wide, and excavated to a depth of -10 feet {NGVDQvILW is -2.09 ft. NGVD)}. The
Mason Creek channel would be dredged from the AIWW to the relocated inlet channel. This channel
would be 3400 feet long and 170 feet wide, excavated to a depth of -8 feet (NGVD). A sedimentation
basin would be excavated adjacent to the new inlet channel, on the inside of the inlet throat. The majority
of the basin would be located south of the dredged channel and would function to capture and retain sand
flows and reduce shoaling effects in Mason Creek. The basin's combined area would be approximately
1000 feet long and average 500 feet in width. It would be excavated to the same depth as the inlet
channel, -10 feet (NGVD). The project would begin with the dredging of Mason creek, excavated
material would be stockpiled, above MHW, at the south end of Figure 8 Island and the north end of
Wrightsville Beach. The work would proceed, east to west, into the areas of the sedimentation basin and
and the new inlet channel, leaving a plug at the west end (AIWR) of Mason Creek and an ocean plug at
New Hanover Co./Mason Inlet Relocation Project
Page 4
the east end of the inlet channel. Dredging from the near shore ocean bottom, -6 to -12 foot contour,
would be utilized to during the initial opening of the inlet. These excavated materials would be pumped
onto the beach at Figure 8 Island. The proposed beach renourishment profile provides for the placement
of 35 to 50 cubic yards of sand per linear foot of shoreline. Deposition of the material would begin at
least 1,500 feet north of the new inlet's position and continue north for approximately 8,500 feet. The
resulting beach profile, after reaching equilibrium, is expected to produce an additional 70 to 90 foot
width to the upper beach with an elevation increase of 6 feet, that will transition to an elevation increase
of 2 feet in the near shore surf zone, on the east side of the approximately 300 feet wide impacted area.
Closure of the the existing inlet and construction of the southern fill area would be completed utilizing
a rapid mechcanical sand moving operation upon successful opening of the new inlet. The resulting fill
area at the north end of Wrightsville Beach would be approximately 1,800 feet long and 1,000 feet wide'
at its base. The submitted project drawings show the top width of the fill area to be 400 feet wide,
constructed to an elevation of +10 feet (NGVD).
10. ANTICIPATED IMPACTS
The excavation of the Mason Creek channel would incorporate 126,324 square feet (2.9 acres) of Smooth
Cordgrass (Spartina alterniflora) marsh. The applicant's EA states that this impact is necessary to restore
an east-west dominant flow to the inlet mouth for stability. The applicant proposes to mitigate for this loss
by replanting a 5.8 acre hurricane overwash fan with Spartina altenz flora, to restore the marsh. This tract
is located in the southwest comer of the project area. The proposed project's total excavation area,
including Mason Creek, the new inlet channel, and the sedimentation basin, would disturb 2, 134,440
square feet (49 acres) of sandy, shallow bottom. The proposed beach renourishment area of the southern
end Figure 8 Island has been previously permitted in conjunction with State Permit # 26-92. The
deposition of this material would disturb 2,550,000 square feet (58.5 acres) of upper beach and inter-tidal
zone along the southern half of the Figure 8 Island oceanfront. And, the infilling of the existing inlet and
southern fill area would incorporate 1, 800, 000 square feet (41 acres) of open water and intertidal area.
Conversely, the relocated inlet would create 1,050,000 square feet (24 acres) of new open water/intertidal
area.
The applicant's EA states that a number of positive impacts would result from the project including:
enhanced nutrient exchange and productivity, as well as, improved water quality resulting from the
restoration of flows to Mason Creek. Also, there would be positive effects on recreational navigation and
public access to the inlet area. Their study also concedes that this proposal is not a permanent solution
to the southerly migration of Mason Inlet. The inlet channel and sedimentation basin would need
maintenance on approximately a five (5) year cycle, as well as, the maintenance of Mason Creek on an
as needed basis. Thus, all of the direct impacts of the project would be repetitive in occurrance,
presumably indefinitely. The proposed project would provide a privately funded approach to address the
beach erosion problems of Figure 8 Island and inlet migration threat to the north end of Wrightsville
Beach, without the use of State or federal public monies.
Submitted by: E.F. Brooks Date: 12/20/99 Office: Wilmington
Form DCM-M -1
APPLICATION
(To be completed by all applicants)
b. City, town, community or landmark
Wriahtsyi 11P RPar`h anA Vit?L1rG 8
1. APPLICANT Island
c. Street address or secondary road number
a. Landowner:
Name New HannvPr C_minty
Address 414 Chestnut Street
City Wilmington . State NC
d. Is proposed work within city limits or planning
jurisdiction? X Yes No
e. Name of body of water nearest project (e.g. river,
creek, sound, bay) Ma a nn T n 1 P t_
Mason' Creek
zip 28401 Day Phone [phone]
Fax [phone]
b. Authorized Agent:
Name Applied Technology & Mgmt.
of North Carolina, Inc.
Address 201 N. Front St., Suite 201
City Wilmington State NC
Zip 28401 Day Phone [phone]
Fax [phone]
c. Project name (if any) -Mason T n l P t-
RPl acati nn Prn? Pr,t
N07F. Permit will be issued in nano of landowner(s), and/or
project name.
2. LOCATION OF PROPOSED
PROJECT
a. County New Hanover
3. DESCRIPTION AND PLANNED USE
OF PROPOSED PROJECT
a. List all development activities you propose (e.g.
building a home, motel, marina, bulkhead, pier, and
excavation and/or filling activities.
Excavation across inlet corridor
easement on Figure 8 Island;
excavation at Mason Creek; filling
existing location of Mason Inlet;.
beachfill at Figure 8 Island
b. Is the proposed activity maintenance of an existing
project, new work, or both? New Work
c. Will the project be for public, private or commercial
use? Public
d. Give a brief description of purpose, use, methods of
construction and daily operations of proposed
project. If more space is needed, please attach
additional pages. See attached

0-4-A n1l"
Form DCM-MP-1
4. LAND AND WATER
CHARACTERISTICS
a. Size of entire trail _ 79.8 Acres (D r e d g e
and fill- areas)
b. Size of individual lot(s) N/A
c. Approximate elevation of tract above MHW or
NWL Varies -2' MHW to +5' MHW
m. Describe existing wastewater treatment facilities.
N/A
n. Describe location and type of discharges to waters
of the state. (For example, surface runoff, sanitary
wastewater, industrial/commercial effluent, "wash
down" and residential discharges.) Hydraulic
dredging with slurry discharges
sites for beachfill and Mason:
Inlet infilling.
d. Soil type(s) and texture(s) of tract Shoals are o. Describe existing drinking water supply source.
unconsolidated sand (SP & SP/SM). Spit is N/A
new an sand unconsoli a e san . Mature
C.
f.
V marsh is silty clay loam.
Vegetation on tract S= n r+.i n;; A l +.arn i ? i nra f
S. Patens,Borrichia Frutescens, Distichlis
pica a, a icornia pp., nio a aniculata,
Cakile Endentula, Hydrocotyle Spp.
Man-nM?,teatures now on tract 5. ADDITIONAL INFORMATION
g. What is the CAMA' Land Use Plan 'land
classification of the site? (Consult the local land use plan.)
X Conservation
X Developed
Rural
Transitional
Community
Other
h. How is the tract zoned by local government?
R20 s
i. Is the proposed project consistent with the applicable
zoning? x_ Yes No
(attach zoning coatpliance certificate, if applicable)
j. Has a professional archaeological assessment been
done for the tract? Yes x No
If yes, by whom? SHPO Guidance Letter
received no professional assessment
k. is, rthre pro JVct rlo edr in a National Registered
Historic District or does it involve a National
Register listed or eligible property?
Yes x_ No
1. Are there wetlands on the site? X Yes No
Coastal (marsh) X Other
If yes, has a delineation been conducted? Yes
(Aaach documentation, if available)
In addition to the completed application form, the
following items must be submitted:
• A copy of the deed (with state application only) or
other instrument under which the applicant claims title
to the affected properties. If the applicant is not
claiming to be the owner of said property, then
forward a copy of the deed or other instrument under
which the owner claims title, plus written permission
from the owner to carry out the project.
• An accurate, dated work plat (including plan view
and cross-sectional drawings) drawn to scale in black
ink on an 8 112" by I V white paper. (Refer to
Coastal Resources Commission Rule V.0203 for a
detailed description.)
Please note that original drawings are preferred and
only high quality copies will be accepted. Blue-line
prints or other larger plats are acceptable only if an
adequate number of quality copies are provided by
applicant. (Contact the U.S. Army Corps of
Engineers regarding that agency's use of larger
drawings.) A site or location map is a part of plat
requirements and it must be sufficiently detailed to
guide agency personnel unfamiliar with the area to the

3 d. Description and Planned Use of Proposed Project
The purpose of this project is to protect homes and upland property at north Wrightsville
Beach from erosion related losses caused by the continued southerly migration of Mason
Inlet. Sand will be excavated from Mason Creek between the ICWW and Figure 8 Island
and transported via pipeline to the existing Mason Inlet and the southerly beaches of
Figure 8 Island.
A hydraulic dredge will be used to excavate material from Mason Creek through the new
inlet location across Figure 8 Island. The sand slurry will be pumped through both
floating and land based pipeline to the locations of fill placement. Pipeline will be
located within established corridors extending to the south end of Figure 8 Island
continuing north to the southernmost 8,500 feet of developed beaches on Figure 8 Island.
A corridor will be established and marked with flagging to lay out pipeline (floating and
fixed lines) between the area(s) of excavation and the stockpile and fill area. The
stockpile area is proposed to be located at the south end of Figure 8 Island, contiguous to
the channel bank at the existing inlet.
Form DCM-MP-1
site. Include highway or secondary road (SR)
numbers, landmarks, and the like.
• A Stormwater Certification, if one is necessary.
• A list of the names and complete addresses of the
adjacent waterfront (riparian) landowners and
signed return receipts as proof that such owners
have received a copy of the application and plats
by certified mail. Such landowners must be advised
that they have 30 days in which to submit comments
on the proposed project to the Division of Coastal
Management. Upon signing this form, the applicant
further certifies that such notice has been provided.
Name See attached list
Address
Phone
Name
Address
Phone
Name
Address
Phone
• A list of previous state or federal permits issued for
work on the project tract. Include permit numbers,
permittee, and issuing dates.
None
• A check for $250 made payable to the Department of
Environment, Health, and Natural Resources
(DEHNR) to cover the costs of processing the
application.
• A signed AEC hazard notice for projects in
oceanfront and inlet areas.
• A statement of compliance with the N.C.
Environmental Policy Act (N.C.G.S. 113A - 1 to
10) If the project involves the expenditure of public
funds or use of public lands, attach a statement
documenting compliance with the North Carolina
Environmental Policy Act.
6. CERTIFICATION AND PERMISSION
TO ENTER ON LAND
I understand that any permit issued in response to this
application will allow only the development described in
the application. The project will be subject to conditions
and restrictions contained in the permit.
I certify that to the best of my knowledge, the proposed
activity complies with the State of North Carolina's
approved Coastal Management Program and will be
conducted in a manner consistent with such program.
I certify that I am authorized to grant, and do in fact,
grant permission to representatives of state and federal
review agencies to enter on the aforementioned lands in
connection with evaluating information related to this
permit application and follow-up monitoring of the
project.
I further certify that the information provided in this
application is truthful to the best of my knowledge.
This is the c2 6 day of Chu a.,t, 19 99
Print Name _ Knryn M_ Frirkrcgn, P_E_
Applied Techno1 y & Mgmt.
Signature Of North ?aroli , Inc.
. _
Please indicate attachments pertaining to your proposed
project.
X DCM MP-2 Excavation and Fill Information
DCM MP-3 Upland Development
DCM MP-4 Structures Information
DCM MP-5 Bridges and Culverts
DCM MP-6 Marina Development
NOTE: Please sign and date each attachment in the
space provided at the bottom of each form.

5. Names of adjacent waterfront owners:
1. Shell Island Homeowners Association
c/o Shanklin & McDaniel
214 Market St
Wilmington, NC 28401
[phone]
2. Geo Henry Hutaff Trust No. 2
cto David Ward
Ward & Smith
1001 College Court
PO Box 867
New Bem, NC 28560
[phone]
3. State of North Carolina
Department of Administration
State Property Office
cto Joe Henderson
116 West Jones Street
Raleigh, NC 27611
[phone]
4. Bruce Cameron
2219 Blythe Road
Wilmington, NC 28403
[phone]
5. Town of Wrightsville Beach
Tony Caudle, Town Manager
321 Causeway Drive
Wrightsville Beach, NC 28480
[phone]
6. Figure 8 Beach Homeowners' Association
clo Edward S. Barclay, Jr., President
15 Bridge Rd
Wilmington, NC 28411
[phone]
Form DCM-MP-2
EXCAVATION
AND FILL
(Except bridges and culverts)
Attach this form to Joint Application for CAMA Major
Permit, Form DCM-MP-1. Be sure to complete all
other sections of the Joint Application that relate to this
proposed project.
Describe below the purpose of proposed excavation or
fill activities. All values to be given in feet. -
Average Fluud
F.xis ft Project
Length Width Depth Depth
Access
channel
(MLW) or (NWL)
Canal
Inlet
Boat
basin
Boat
ramp
Rock
groin
Rock
breakwater
Other Beach
(Excluding
shomline
stabilization)
3400 1
70 +2 to
, -8
GVD NGVD
2100 500 Varie -10
NGVD

: •f

•:: •'w<:Jf:.J-:,tom: si•;•cx:3:::?
0,00 50 - +4 to +8 to
.100 -6 -6
1. EXCAVATION
a. Amount of material to be excavated from below
MHW or NWL in cubic yards _ 49.1 ,D.Q0 - .y
b. Type of material- to be excavated uriconsolidate(
fine/medium grain sand, SP & SP/SM'
classified soils
c. Does the area to be excavated include coastal
wetlands (marsh), submerged aquatic vegetation
(SAVs) or other wetlands? X Yes No
d. Highground excavation in cubic yards 290,000 -c;
2. DISPOSAL OF EXCAVATED
MATERIAL
a. Location of disposal area 1. Mason Inlet and
2. southerly 2 miles of developed
shoreline at Figure 8 Island
b. Dimensions of disposal area. 1. .3 8.7 acres a n c
2. varies 50 to 10 ' x 10,000'
c. Do you claim title to disposal area?
Yes X No
If no, attach a letter granting permission from the
owner.
d. Will a disposal area be available for future
maintenance? X Yes No
If yes, where? Construction easements
across lands south of-inlet
_._-corri-dor will be executed (purchase(

Revised 03/95
Form DCM-MP-2
e. Does the disposal area include any coastal wetlands
(marsh), SAVs or other wetlands?
Yes X No
C Does the disposal include any area in the water?
X Yes No
If yes,
(1) Amount of material to be placed in the
waterA) 395,700 cy B) 308,300
(2) Dimensions f fill area A) 1,700, x
1,000' Bg 8,5001x 75'
(3) Purpose of fill A) Fi 1 i PY; g+;
inlet B) Nourish beach
3. SHORELINE STABILIZATION
a. Type of shoreline stabilization N/A
Bulkhead Riprap
b. Length
c. Average distance waterward of MHW or NWL
d. Maximum distance waterward of MHW or NWL
b. Will fill material be placed in coastal wetlands
(marsh), SAVs or other wetlands?
Yes X No
If yes,
(1) Dimensions of fill area
(2) Purpose of fill
5. GENERAL
a. How will excavated or fill material be kept on site
e. Shoreline erosion during preceding 12 months and erosion controlled? Long d i k g
parallel to shoreline
(Source of information)
f. Type of bulkhead or riprap material
g. Amount of fill in cubic yards to be placed below
water level
(1) Riprap
(2) Bulkhead backfill
h. Type of fill material
b. What type of construction equipment will be used
(for example, dragline, backhoe, or hydraulic
dredge)?
Hydraulic dredge, Excavators and
Bulldozers
c. Will wetlands be cr:,ssed in transporting equipment
to project site? . Yes X No
If yes, explain steps that will be taken to lessen
environmental impacts.
i. Source of fill material
4. OTHER FILL ACTIVITIES
(Excluding Shoreline Stabilization)
a. Will fill material be brought to site?
X Yes No (Hydraulic
Karyn M. ckson, P.E.
Applicant r Pmj
Sig cure
26-J9-41
placemen '?-
Revised 03/95
S l
rs' l
r x
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Appendix H
Material Characteristics At Mason Creek.Channei
and Figure ".8. Island
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Physical and Biological
Monitoring Plan
Submitted to:
North Carolina Division of Coastal Management
U.S. Army Corps of Engineers
Applicant:
New Hanover County
Prepared by: 77
'77 7 -7

Applied Technology and Management :of North Carolina, Inc.
Land Management Group, Inc.
October, 1999
)qm
APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA. INC.
AND BIOLOGICA
NITO
MASON INLET RELOCATION PROJECT
PROJECT SUMMARY
VV E
C ziv
?tiJV U 8 1999
-10 ?.,STa n ? ?
- E? VTNT
On behalf of New Hanover County, Applied Technology and Management of North Carolina,
Inc. (ATM) has submitted a permit application to the Division of Coastal Management (DCM)
and the U.S. Army Corps of Engineers (USCOE) for activities associated with the proposed
relocation of Mason Inlet. The purpose of this project is to protect homes and upland property
at the northern end of Wrightsville Beach from erosion losses resulting from the continued
southerly migration of Mason Inlet. Sand will be excavated from Mason Creek between the
ICWW and Figure Eight Island and transported via pipeline to the existing Mason Inlet and the
southern oceanfront beaches of Figure Eight Island. An Environmental Assessment (EA)
assessing existing environmental conditions and potential project impacts has been prepared
and distributed to participating 'regulatory agencies for review. The following plan outlines
various components of the physical and biological monitoring that will be used to evaluate
potential impacts associated with the inlet relocation project. The EA should be referred to for
additional information regarding project design and potential impacts to environmental
resources.
BEACH AND OFFSHORE PROFILES
Beach and offshore profiles shall be measured at 20 reference monuments to be established
along the Figure 8 Island, Mason Inlet and Wrightsville Beach shoreline adjacent to the Mason
Inlet Relocation Project Area. Profiles will extend along the shore normal azimuths, from the
backbeach (west of the existing dune or berm feature) approximately 1,500 feet offshore (to the
-25-foot NGVD contour). The average spacing between monuments will range from 250 feet
near the inlet to 1,000 feet at distances greater than 1,500 feet from the new and the closed
Mason Inlet location.
In addition, profiles at the adjacent beaches monuments will also be similarly measured. The
adjacent survey limits will extend approximately 3,000 feet north of the relocated inlet
monuments (MI-1 to MI-5) and 5,000 feet south of the inlet (MI-11 to MI-20). The adjacent
beaches profiles will allow monitoring of sand spreading and movement adjacent to the
relocated Mason Inlet.
Beach profiles will be performed immediately before and after construction. Additional surveys
will be performed at 6 months, 1 year, and 2 years following project completion. Additional
annual surveys will be performed if the. North Carolina Division of Coastal Management (DCM)
determines them to be necessary. Profiles will also be conducted following significant storm
events during the 24-month monitoring period following completion of construction.
201 North Front Street, Suite 201
Wilmington. North Carolina 28401
TEL [phone] FAX [phone]
-1-
99265A-Hydro%BiologMonitoringPlan 102599pce
Vertical and horizontal control will be referenced to NGVD 1929 and North Carolina State Plane
Coordinate System (NAD 1927), respectively. Survey line azimuths will be identified by
magnetic bearing. Survey data will be submitted to the DCM in the form of cross-sectional
profile plots and on 3.5" disk in the DCM designated digital format. A report will be submitted
for each post-construction survey which will document the results of volumetric and shoreline
change analyses to the Inlet, sedimentation basin and the ebb tidal shoal(s) in the Project area
and along adjacent beaches.
INLET AREA BATHYMETRY
Bathymetry at the interior inlet will be measured prior to construction, immediately following
construction, and annually thereafter for the 24-month monitoring period. The surveys will
consist of 30 lines spaced approximately 150 feet apart. The lines will run approximately 1,000
to 1,500 feet following the long axis of the inlet (east to west). The data and volumetric change
analyses will be included in the 1-year and 2-year post-construction hydrographic monitoring
reports indicated above.
SURFICIAL SAND SAMPLING
Surface sand samples will be collected immediately following construction and concurrently with
the 12 month beach profile surveys. Sand samples will be collected along eight (8) longshore
transects. Sand samples will be collected at elevations +10, +5, 0,-5, -10, and -15 feet NGVD.
Samples will be analyzed using standard ASTM procedures to determine the grain size
distribution (8 sieves). Results will be submitted to the DCM with an analysis of the longshore
and cross-shore adjustment of the beaches and inlet channel banks and the ebb shoal.
AERIAL PHOTOGRAPHY
Color, vertical aerial photographs shall be flown along the Project shoreline at the time of each
monitoring survey. The scale of the photographs shall be 1 inch equals 200 feet. The flight line
shall begin 3,000 feet north of the inlet and proceed southward at distance of 10,000 feet, 7,000
feet south from the new inlet location.
Each photograph shall include the entire beach, nearshore environment, and sufficient upland
features (i.e., beach-fronting buildings, roads, etc.) to determine the location of any photograph.
The shoreline location in any image should be approximately half way across the width of the
photograph. Consecutive photographs shall have sufficient overlap (approximately 20%) to
identify common points of interest. Photographs shall be taken prior to 2:00 PM to avoid
building shadows cast towards the beach.
Local predicted tides will be used to determine flight times so subsequent photography events
will occur during similar times in the tidal cycle. Photographs will not be rectified, but horizontal
ground control will be established by setting sufficiently sized aerial targets (4' x 4') on the
reference monuments in the days prior to the flight. In the event that a monument is either not
visible due to vegetation or located in an area of heavy traffic, the aerial target shall be offset
from the monument along the profile azimuth. This offset distance and azimut ill
the target-setting party's field notes for use during any subsequent photographic n ?. j 2H V E
TWIT h:3 ?! d 8 1999 1
?: C.
99265A-Hydro\Bio?oy'?ton?o°?f?§P Coastal Engineers, scientists & Management Consultants D1 V! C`II111VK 1 nC
S . .ti: • S
`nACTAI KAAnlA(,%9: :
BIOLOGICAL MONITORING
The goal of the biological monitoring plan is to assess and document potential effects of project
activities on primary productivity, faunal utilization, and substrate texture/organic content of
marsh areas adjacent to the proposed work zone. Pre- and post-construction monitoring will
provide quantitative data and qualitative observations that can be used determine if any
deleterious effects to the marsh habitat are directly attributable to the inlet relocation project.
The extent to which monitoring parameters will be affected depends on various conditions (e.g.
the character of the dredged material, tidal and current regimes, etc.) and any system
responses will likely be distributed in a linear fashion from Mason Creek.
MONITORING PARAMETERS
Selection of monitoring parameters has been based upon those factors potentially impacted by
project activities and those readily sampled and evaluated. The following monitoring elements
have been selected:
!LAS
?p
(1) Spartina stem density 4 c ?7
(2) Mature (>30 cm height) Spartina stem height
(3) Percent sand, silt, and clay of surface substrate Fov 0 8 1999
(4) Percent organic content of surface substrate
(5) Sedimentation rate ?I?pseinh? nc
(6) Benthic macroinvertebrate utilization n A 0-rA I h ®n1 A Fk"ENT
(7) Wildlife utilization
Evaluation of each of these parameters is discussed in the following section.
BIOLOGICAL SAMPLING AND ANALYSIS METHODOLOGY
Sampling efforts will focus on the area of potential impact where biota and physical conditions
(e.g. soil texture) are most likely affected by project activities and associated perturbations such
as altered flooding regime and sedimentation. As discussed earlier, any perturbations will
manifest in system responses distributed linearly from Mason Creek. Therefore, three
permanent 300-foot monitoring transects will be established along a north-south axis on both
sides of Mason Creek (totaling six transects). Four one-meter square quadrats for each
transect (located 50, 100, 150 and 300 feet away from Mason Creek) will be sampled for stem
density and height of Spartina. The quadrat located furthest from Mason Creek will serve as
the control plot for each transect. (Refer to the enclosed map depicting monitoring transects
and plots.)
Sediments will be characterized according to percent sand/silt/clay and percent organic matter.
A composite sample will be collected for the 50, 100, and 150-foot plots. One sample will be
collected for each control plot. In addition, metal rebar installed flush with the sediment surface
prior to project construction will used to evaluate sediment deposition and/or loss over time for
each plot.
Faunal utilization of marsh habitat will be evaluated through species lists and relative densities
of epibenthic macroinvertebrates and wildlife along transect corridors. Indirect evidence and
...Arm /T
992651-1yd,.XB y zr?i'n 3?k??c.?- Coastal Engineers, scientists & Management Consultants
direct observation will be used to document the presence of a species within the transect
corridor. Each transect corridor will extend 150 feet away from Mason Creek and will be 3 feet
wide. Separate control transect corridors (150 feet by 3 feet) will be established in an east-west
orientation as depicted on the enclosed map.
Each survey will incorporate photographic documentation depicting site conditions along each
transect corridor. During each monitoring period, close-up and panoramic views will be
photographed at designated stations.
Pre-dredging and the post-dredging mean values of each parameter will be statistically
compared using Analysis of Variance (ANOVA)/paired t-tests or Wilcoxon signed rank tests.
Ninety-five percent confidence intervals will be used to determine statistically significant
differences of means (means will be significantly different if confidence intervals do not
overlap). Proximal and/or distal changes (if any) in sedimentation rates, stem density and/or
stem height will also be statistically determined.
BIOLOGICAL MONITORING SCHEDULE
The effects of any perturbation on vegetative conditions will be most pronounced and
detectable during active growth and development. Therefore, monitoring will occur during the
middle of the growing season (June/July) once each year subsequent to project completion for
a duration of two years. Sampling for baseline conditions will be conducted in the June/July
prior to project initiation (provided that there is sufficient time once the project permit has been
obtained). An immediate pre-construction survey (conducted within 30 days prior to project
initiation) will detect changes resulting from storm events during the elapsed time between
June/July and the start of project construction. A total of four monitoring events will be used to
determine if impacts are directly attributable to project activities. All the parameters discussed
in the previous section will be evaluated during each monitoring event.
REPORT DOCUMENTATION
Monitoring reports documenting site conditions and findings will be prepared and submitted
annually to the Division of Coastal Management, the U.S. Army Corps of Engineers, and the
Division of Water Quality by September 15`x' (following the June/July monitoring event). The
following information will be provided in each report:
(1) Project overview
(2) Site parameters monitored
(3) Methodology used to evaluate parameters
(4) Data analysis
(5) Summary of findings
(6) Prints of photographs at specified stations
(7) Maps depicting location of transects and sampling plots
i? 6CEIVE
r""v 0 8 1999
ptrnn?r,?? n?
..."ATA I
F n?,??,
99265A-Hldr.\Bi.% 4r.,'n 'fUZ? .8' Coastal Engineers, scientists & Management Consultants
MITIGATION PROPOSAL DRAFT
MASON INLET RELOCATION PROJECT
NEW HANOVER COUNTY, APPLICANT
LAND MANAGEMENT GROUP, INC. APPLIED TECHNOLOGY &
MANAGEMENT, INC.
OCTOBER 1999
8 1-299
?697lPtet??.s -C![.?`
,SCENE
t?OV U 8 1999
D
DIVISION OF
MASON INLET RELOCATION PROJECT SUMMARY "O A CTtl 1 11A A NlAr,2 P-1 ENT
On behalf of New Hanover County, Applied Technology and Management of North Carolina, Inc.
(ATM) has submitted a permit application to the Division of Coastal Management (DCM) and the
U.S. Army Corps of Engineers (USCOE) for activities associated with the proposed relocation of
Mason Inlet (refer to Figure 1, `Location Map'). The purpose of this project is to protect homes
and upland property at the northern end of Wrightsville Beach from erosion losses resulting from
the continued southerly migration of Mason Inlet. Sand will be excavated from Mason Creek
between the ICWW and Figure Eight Island and transported via pipeline to the existing Mason
Inlet and the southern oceanfront beaches of Figure Eight Island. An Environmental Assessment
(EA) assessing existing environmental conditions and potential project impacts has been prepared
and distributed to participating regulatory agencies for review. The following proposal outlines
restoration efforts as mitigation for anticipated wetland impacts associated with the inlet
relocation project. The EA should be referred to for additional information regarding project
design and potential impacts to environmental resources.
MITIGATION CONSIDERATIONS
Avoidance and Minimization: The project design of the relocation of Mason Inlet has sought
to avoid and minimize impacts to existing marsh habitat. However, a continuous 170-foot wide
channel will need to be constructed through an area of recently accreting marsh on the south side
of Mason Creek. This channel is essential for re-establishing the ebb flow dominance of Mason
Creek over Banks Channel, ultimately resulting in a more "stable" inlet location and minimizing
the frequency of inlet maintenance activities. Therefore, the proposed design will impact 2.9 acres
of volunteer Spartina alterniflora habitat (refer to Figure 2, `Proposed Project'). As described in
the EA, this area of marsh is characterized by a lower level of habitat value and overall
productivity than the marsh to the north side of Mason Creek (classified asORW). Project design
of the inlet relocation has sought to avoid impacts to the mature stands of S. alterniflora.
Therefore, no excavation will take place within the mature, well-established marsh habitat on the
north side of Mason Creek.
Wetlands Impacted: An area of 2.9 acres of recently established S. alterniflora habitat will be
impacted. This area represents approximately 5.6 % .of the 51.9 total acres to be excavated for the
inlet relocation project.
Proposed Mitigation: In order to mitigate for the impacts to coastal marsh area, the applicant
proposes to plant S. alterniflora seedlings on suitable intertidal flats adjacent to the project area in
coordination with the Division of Coastal Management (DCM). Mitigation is proposed at a 2:1
ratio; therefore, a total of 5.8 acres of S. alternflora marsh will be restored.
Mitigation Goals and Objectives: The objective of the proposed wetland mitigation is to double
the spacial extent of marsh impacted by the planned Mason Creek dredging work (2:1). In
_ :•• Of '
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C?
(1970 location)
Project Location and
Current Location of
Mason Inlet (1999)
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APPLICATION BY:HEW NOVEF.' CQIJINTY
g a.& /q9
DATE: 8/24/99
LOCATION MAP
Figure I
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
AT: WRIGHTSVILLE BEACH AND
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COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA
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APPLICATION BY:NEW HANO` ER COUNTY PROPOSED PROJECT PROPOSED: MASON INLET RELOCATION
VERTICAL DATUM: NGVO (MSL 92y) AT: WRIGHTSVILLE BEACH AND
Figure 2 FIGURE 8 ISLAND
HORIZONTAL DATUM: NC GRI ND 83
COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY
414 CHESTNUT S7 STATE: NORTH CAROLINA
DATE: 8/24/99 (o q WILMINGTON. NC 28401 AWJ
SHEET 9 .a'"
addition, planting of S. alterniora on suitable intertidal shoals will help to restore marsh areas
severely impacted by recent hurricanes. The long-term goal of the mitigation project ttQ,
stablish marsh habitat functionally equivalent to the impacted areas. , (? '!
eEIVE
a
SITE CHARACTERIZATION `p f .?`z B ici99
St,laC"r?4?1 s'1?
Intertidal areas suitable for coastal marsh restoration have been identified based upon Tin dal range,
substrate characteristics, and exposure to wave energy. Areas recently damaged by overwash
events associated with tropical storm systems have been specifically targeted for restoration
activities. Collectively, recent storms have damaged or buried approximately 20 acres of
productive marsh between the Shell Island Resort and Mason Creek.
In light of these considerations, two primary mitigation areas have been selected. As depicted on
the enclosed site design map (Figure 3), these intertidal flats are located along the edge of the
interior marsh lagoon system approximately 1500 feet south of the proposed new inlet location.
The distance from the mouth of the proposed inlet will help minimize exposure to high velocity
currents that could threaten the stability and success of the Spartina plantings. In addition, the
location of the potential restoration areas are subjected to relatively low wind fetch distances.
Wind fetch distances of less than 1.0 nautical mile have been demonstrated to limit damage from
wave action significant enough to eliminate the need for maintenance planting (Broome, Seneca
and Woodhouse, 1986).
SITE ELEVATION
Subsequent to project completion and equilibration of channel side slopes, beachfront sediments,
and currents; grades in the mitigation area will be confirmed to ensure that surface elevations do
not deviate significantly from the pre-construction intertidal contours. Specific planting zones will
be selected in areas exhibiting gradual slopes (1-3%) in order to maximize the intertidal area and
dissipate wave energy. Extremely flat or irregular surfaces will be avoided, for these areas tend to
favor localized hypersaline conditions unsuitable for plant growth (Broome, 1990). Elevations and
tidal range will simulate that of natural reference marshes. This type of mitigation will not warrant
the use of water control structures or sediment and erosional control measures.
PLANTING PLAN
Nursery stock seedlings of S. alterniflora grown specifically for wetland creation and restoration
projects in this region will be planted on 2' spacings in areas of suitable elevation,
microtopography, and substrate characteristics. Mature seeds will be collected from local
Spartina stands during the September or October immediately after the permit for the inlet
relocation project has been obtained . Seeds will be refrigerated, threshed, and then stored in a
container filled with potting soil and salt water (35 parts per thousand) at 35 to 40° F. Seedlings
will then be ready for planting on the mitigation site during April of the next calendar year. Actual
planting locations will be within sandy sediments of the upper half of the local tidal range. The
mitigation area will comprise 5.8 acres (corresponding to approximately 60,000 seedlings).
An alternative restoration scheme involves transplanting individual Spartina plants from the
existing marsh stand to be excavated. However, this option is considered problematic. The
construction sequence involves excavating the Mason Creek segment before closing the existing
inlet. Since the proposed mitigation area is situated directly to the west of the existing inlet,
transplants would be subjected to direct wave action and high velocity flow, severely
compromising plant health. Temporary storage of transplanted Spartina during inlet relocation is
not considered a viable option given the inherent difficulties of handling and maintaining
transplants. Therefore, planting nursery stock seedlings is considered to be the most advantageous
method of restoring Spartina habitat.
Once the existing inlet mouth has been closed, flow velocities should be reduced in the primary
overwash area. Spartina growth would no longer be hampered by prohibitive flow rates or an
excessive shifting sediment load. As such, it is anticipated that the planted wetland area will
survive with limited mortality. Recruitment of new Spartina growth within the mitigation area will
be promoted by active rhizomal proliferation and seed dispersal of adjacent natural stands.
SOIL AMENDMENTS
Each seedling will receive a small amount of Osmocote (or equivalent) slow-release fertilizer
within the planting hole to accelerate initial growth. Slow-release fertilization is considered
particularly advantageous in sandy substrates (which exhibit a lower capacity to retain applied
nutrients) and has been demonstrated to be an effective practice in marsh restoration and creation
projects (Broome, 1990). No further soil amendments are proposed at this time. The addition of
organic matter to the substrate has been demonstrated to enhance rhizome growth within an
artificial, controlled mesocosm (Padgett and Brown, 1998). However, the field application of
organic material would involve incorporating peat into the upper soil through mechanized tilling
over the entire mitigation area. This would disturb the stability of the soil profile, thereby making
the sandy substrate more susceptible to erosion during tidal exchanges and threatening the
immediate stability of the planted materials.
SITE PERFORMANCE CRITERIA
Site success criteria are used to evaluate the development of a created or restored wetland in
relation to stated project goals and objectives. Monitoring of various biological and
physiochemical parameters will help demonstrate the relative success of a compensation site.
These `performance' criteria are agreed upon by the applicant and the respective regulatory
agency(s) as part of the permitting process.
Since this compensation project seeks to restore marsh habitat through plantm ,r CyFf VE
Spartina seedlings, the primary success criteria will be: I :?_.`i 0 8 1999
y
MKIT
"Demonstrated survival rate of plantings and naturally colonized individuals to exceed
70% after the second monitoring year. "
Additional site success criteria commonly utilized for other wetland compensation projects are not
suitable for this project. For instance, soil development (i.e. percent organic matter, nutrient
composition, bulk density, porosity, etc.) of created and restored tidal marshes usually can not be
demonstrated to simulate the substrate of natural reference marshes within the stated monitoring
period (Broome, 1990).
MONITORING PLAN
Periodic monitoring of site performance criteria will be conducted by the applicant at prescribed
intervals to evaluate project development. Parameters such as percent survivorship of plantings
and soil texture/organic content will be quantitatively evaluated in three permanent 25 meter-
square plots representative of the planting area. The corners of each plot will be staked with metal
rebar installed flush with the sediment surface. Therefore, relative sediment deposition and/or
sediment loss within the mitigation area can be evaluated. Qualitative observations of faunal
(including epbenthic and wildlife) habitat use will be recorded. In addition, photographic
documentation (close-up and panoramic views) of plantings will occur at specified stations. An
initial "as-built" survey will be conducted immediately following completion of plantings. This
survey will include the limits of natural Spartina stands that exist adjacent to the planting area.
Monitoring will then be conducted once annually during each subsequent April/May for a duration
of three years documenting fulfillment of performance criteria. Monitoring reports will be
prepared and submitted to the DCM, COE, and DWQ by August 15`x' of that year. The following
information will be provided in each report:
1. Reference permit number D5
2. Summary compensation site project goals and objectives ECEHVE
3. Overview of the compensation
4. Site parameters monitored
5. Methodology used to evaluate parameters ??99
6. Data analysis
7. Summary of findings a E^ -KIT
8. Maintenance measures
9. Remedial measures
10. Prints of photographs at specified stations
11. Maps identifying adjacent natural marsh habitat, planting zones, areas monitored,
transects, etc., as appropriate.
Reports will document annual findings and evaluate the development of the project site with
respect to performance criteria and target goals.
Annual site monitoring will help to identify maintenance issues as they arise. Successful wetland
compensation will require maintenance activities as needed throughout the duration of the
monitoring period. Maintenance activities may include plant replacement and/or fertilization. If
performance criteria are not met, reasons for deficiencies will be determined and appropriate
remedial action will be conducted.
DIV!C C."" "=
-nne-rf-' 1kAAK1nrc'kAGnIT
I':' ? 81999
D5
LITERATURE CITED
Broome, S. W., E. Seneca and W. Woodhouse, Jr. 1982. Building and Stabilizing Coastal Dunes
with Vegetation. Pub. UNC Sea Grant 85-05.
Broome, S. W. 1990. Creation and restoration of tidal wetlands of the Southeastern United States.
Pp. 37-72 in Kusler, M.E. (eds.) Wetland Creation and Restoration: the Status of the
Science. Island Press, Washington DC.
Padgett, D.E. and J.L. Brown. 1999. Effects of drainage and soil organic content on growth of
Spartina alterniflora (Poaceae) in an artificial salt marsh mesocosm. American Journal of
Botany. 86(5). 697-702.
'V ??'?81999

D
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3
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01
Figure 3 I I
Potential Wetland Mitigation Sites ?Pxna?
_
j ?, ?,?r? ?NC?ccr 1 WNAGEMEN
CF NOR-, -i C?JRCI;N ;NC.

"PEND1X V
HYDRODYNAMIC MODELING
OF MASON INLET AND THE
MIDDLE SOUND ESTUARY
New HaiEovc,r County, North Carolina

Applied Science
Associates, Inc.

APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA, INC.

`JAN 1 0 2001
appendix O
Hydrodynamic Modeling of
Mason Inlet and the Middle-Sound
Estuary, New Hanauer County,
North Carolina
Mason Inlet Relocation Project
PREPARED BY:
APPLIED TECHNOLOGY AND MANAGEMENT OF NORTH CAROLINA, INC.
WILMINGTON, NC
PREPARED FOR:
NEW HANOVER COUNTY
AUGUST 2000
Table of Contents
1. INTRODUCTION .............................................................................................................................................................1
1.1. STUDY SCOPE AND OBJECTIVES .....................................................................................................................2
1.2. PROJECT LOCATION ........................................................................................................................................2
1.3. REPORT OUTLINE ............................................................................................................................................2
2. DATA COLLECTION ......................................................................................................................................................3
2.1. TIDAL DATA ....................................................................................................................................................3
2.2. FLOW DATA ....................................................................................................................................................4
2.3. HYDROGRAPHIC DATA ...................................................................................................................................5
3. MODEL DESCRIPTION .................................................................................................................................................6
3.1. HYDRODYNAMIC MODEL ...............................................................................................................................6
3.2. GRID GENERATOR ......................................................................................................................................... .. 7
3.3. MARSHES ...................................................................................................................................................... .. 8
4. MODEL SET-UP ............................................................................................................................................. ...............10
4.1. MODEL GEOMETRY ...................................................................................................................................... 10
4.2. BATI-ra ETRY ............................................................................................................................................... 10
4.3. MARSHES ...................................................................................................................................................... 11
4.4. TIDAL FORCING ............................................................................................................................................. 11
5. MODEL CALIBRATION .............................................................................................................................................13
5.1. MODEL TIME STEP AND FRICTION COEFFICIENT .........................................................................................13
5.2. MODELIDATA COMPARISONS ......................................................................................................................13
5.2.1. GRAPHIC COMPARISON OF TIDES ............................................................................................................14
5.2.2. GRAPHIC COMPARISON OF FLOWS .........................................................................................................14
5.2.3. STATISTICAL RESULTS .............................................................................................................................14
5.3. FLUSHING ......................................................................................................................................................14
6. PROJECT ALTERNATIVES ANALYSIS ................................................................................................................16
6.1. INITIAL ALTERNATIVES ANALYSIS .............................................................................................................. 17
6.1.1. SCENARIOI .............................................................................................................................................. 17
6.1.2. SCENARIO 2 .............................................................................................................................................. 17
6.1.3. SCENARIO 3 .............................................................................................................................................. 18
6.1.4. SCENARIO 4 .............................................................................................................................................. 18
6.1.5. SCENARIO 5 .............................................................................................................................................. 18
6.1.6. SCENARIO 6 .............................................................................................................................................. 19
6.1.7. SCENARIO 7 .............................................................................................................................................. 19
6.1.8. SCENARIO 8 .............................................................................................................................................. 20
6.1.9. SCENARIO 9 .............................................................................................................................................. 20
6.1.10. SCENARIO 10 ............................................................................................................................................ 20
6.1.11. SCENARIO II ............................................................................................................................................ 21
6.1.12. SCENARIO 12 ............................................................................................................................................ 21
6.1.13. COMPARISON OF INITIAL TWELVE ALTERNATIVES MODELED .............................................................. 22
6.2. ADDITIONAL ALTERNATIVES ANALYSIS ..................................................................................................... 22
6.2.1. CLOSURE OF MASON INLET ..................................................................................................................... 23
6.2.2. MASON INLET MIGRATION ...................................................................................................................... 23
6.2.3. BANKS CHANNEL SHOALED TO 4-FT DEPTH ........................................................................................... 23
6.2.4. NARROWER MASON CREEK ..................................................................................................................... 23
6.2.5. SEDoAENT BASIN SHIFTED NORTH .......................................................................................................... 24
6.2.6. SEDmiENT BASIN SHIFTED NORTH AND NARROWER MASON CREEK ................................................... 24
6.2.7. NO DREDGING IN MASON CREEK ............................................................................................................ 25
7. ADDITIONAL MODEL ANALYSIS .......................................................................................................................... 30
7.1. FLUSHING OF THE SEDIMENT BASIN ............................................................................................................ 30
7.2. COMPARISON OF MEASURED AND SIMULATED TIDAL PRISMS ................................................................... 30
7.3. EXPECTED CHANGE IN TIDAL CHARACTERISTICS ....................................................................................... 31
7.4. EXPECTED AREA OF INFLUENCE OF CHANGE IN HYDRAULICS ................................................................... 31
7.5. CHANGES IN FLOW IN THE VICINITY OF MASON INLET ............................................................................... 32
8. CONCLUSIONS ............................................................................................................................................................. 36
9. REFERENCES ................................................................................................................................................................37
LIST OF TABLES
2-1 Instrument Specifications and Locations ........................................................................................3
2-2 ADCP Transect Locations ...............................................................................................................4
5-1 RMS Error Results for Water Surface Elevations ........................................................................15
6-1 Summary of Project Alternative Modeling Scenarios ...................................................................26
6-2 Comparison of Predicted Tidal Prism and Flow Distribution for Modeled Project
Scenarios .......................................................................................................................................27
6-3 Comparison of Maximum Predicted Depth Averaged Current Velocities for
Modeled Project Scenarios ...........................................................................................................29
7-1 Comparison of tidal prism calculated from ADCP flow measurements
and from the hydrodynamic model output ....................................................................................33
7-2 Simulated tidal prisms for an M2 spring tide .................................................................................33
7-3 Pre- and post-project flow rates in Masonboro Inlet, Mason Inlet and Rich Inlet during an
M2 spring tidal cycle ......................................................................................................................34
7-4 Pre- and post-project flow rates in the vicinity of Mason Inlet ......................................................35
?1J
LIST OF FIGURES
(placed behind each section)
1-1 Project Location Map
2-1 YSI Instrument Locations
2-2 ADCP Transect Locations
4-1 Study Area Digitized Shoreline
4-2 Model Grid for Existing Conditions
4-3 Model Grid at Mason Inlet for Existing Conditions
4-4 Model Bathymetry for Existing Conditions
4-5 Model Forcing Compared to Measured Tides
5-1 Comparison Measured and Simulated Water Surface Elevations at YS101, YS102 and YS103
5-2 Comparison Measured and Simulated Water Surface Elevations at YS104, YS105 and YS106
5-3 Comparison Measured and Simulated Water Surface Elevations at YS107 and YS108
5-4 Comparison of Measured and Simulated Flows at ADCP01 and ADCP02
5-5 Comparison of Measured and Simulated Flows at ADCP03 and ADCP04
5-6 Comparison of Measured and Simulated Flows at ADCP05 and ADCP06
5-7 Comparison of Measured and Simulated Flows at ADCP07 and ADCP08
5-8 Flushing Evaluation, Percent Mass Remaining over time for Existing Conditions
6-1 Scenario 1 - Model Grid
6-2 Flushing Evaluation, Percent Mass Remaining over time for Scenario 1
6-3 Scenario 2 - Model Grid
6-4 Flushing Evaluation, Percent Mass Remaining over time for Scenario 2
6-5 Scenario 3 - Model Grid
6-6 Flushing Evaluation, Percent Mass Remaining over time for Scenario 3
6-7 Scenario 4 - Model Grid
6-8 Flushing Evaluation, Percent Mass Remaining over time for Scenario 4
6-9 Scenario 5 - Model Grid
6-10 Flushing Evaluation, Percent Mass Remaining over time for Scenario 5
6-11 Scenario 6 - Model Grid
6-12, Flushing Evaluation, Percent Mass Remaining over time for Scenario 6
6-13 Scenario 7 - Model Grid
6-14 Flushing Evaluation, Percent Mass Remaining over time for Scenario 7
6-15 Scenario 8 - Model Grid
6-16 Flushing Evaluation, Percent Mass Remaining over time for Scenario 8
6-17 Scenario 9 - Model Grid
6-18 Flushing Evaluation, Percent Mass Remaining over time for Scenario 9
IV
6-19 Scenario 10 - Model Grid
6-20 Flushing Evaluation, Percent Mass Remaining over time for Scenario 10
6-21 Scenario 11 - Model Grid
6-22 Flushing Evaluation, Percent Mass Remaining over time for Scenario 11
6-23 Scenario 12 - Model Grid
6-24 Flushing Evaluation, Percent Mass Remaining overtime for Scenario 12
6-25 Modeled Current Vectors During Flood Tide Conditions for Scenario 1
6-26 Modeled Current Vectors During Flood Tide Conditions for Scenario 11 (No Sediment Basin)
6-27 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 13
6-28 Flushing Evaluation of Banks Channel, Percent Mass Remaining over Time for Scenario 13
6-29 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 14
6-30 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 15
6-31 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 16
6-32 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 17
6-33 Scenario 18 - Model Grid
6-34 Scenario 18 - Ebb Current Vectors
6-35 Scenario 1 - Ebb Current Vectors
6-36 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 18
6-37 Scenario 19 - Model Grid
6-38 Scenario 19 - Ebb Current Vectors
6-39 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 19
6-40 Scenario 20 - Model Grid
6-41 Flushing Evaluation of AIWW, Percent Mass Remaining over Time for Scenario 20
7-1 Flushing Evaluation of Sediment Basin, Percent Mass Remaining over Time for Scenario 1
7-2 Simulated Changes in High Tide Surface Elevation due to Project
7-3 Simulated Changes in Mid-ebb Tide Surface Elevation due to Project
7-4 Simulated Changes in Mid-ebb Tide Surface Elevation due to Project
V
Hydrodynamic Modeling of Mason Inlet and
the Middle Sound Estuary, New Hanover
County, North Carolina
Mason Inlet Relocation Project
1. INTRODUCTION
Applied Technology and Management, Inc. of North Carolina (ATM) performed a computer
model study in support of the permitting and design of the Mason Inlet Relocation Project.
The model study is summarized in the report titled "Hydrodynamic Modeling of Mason Inlet
and the Middle Sound Estuary, New Hanover County, North Carolina" (ATM, 1999a). The
study included the application of the model WQMAP to the study area, the calibration of the
model using measured field data (i.e., water elevation and flow measurements), and the use
of the model as a predictive tool to evaluate various project design scenarios. The model
was used for the purposes of predicting the immediate post-project tidal prisms, current
velocities and flushing characteristics for various design alternatives.
The model study was reviewed by the US Environmental Protection Agency (EPA), the US
Fish and Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS), and the
US Army Corps of Engineers (USACE) Wilmington District. Subsequent to this review,
additional modeling and analysis was performed to respond to comments by the reviewers
and to further evaluate project design altematives. This work was summarized in the report
"Additional Hydrodynamic and Flushing Model Scenarios - Mason Inlet Relocation Project"
(ATM, 1999b).
The above reports were reviewed by the USACE Wilmington District, the USACE Waterways
Experiment Station (WES), and Dr. John Fisher of North Carolina State University (as an
independent reviewer for New Hanover County). These reviewers found that the model was
used appropriately and sufficiently calibrated. However, these reviewers also requested
additional modeling analysis to further examine tidal dominance, tidal prisms, flow paths and
current velocities in the relocated inlet.
ATM (1999b) was revised in April 2000, and it was provided as an appendix to the revised
April 2000 Environmental Assessment (EA) document for the Mason Inlet Relocation Project.
The report includes additional modeling scenarios and analysis to respond to the comments
of the reviewers. Also, the report text includes a review of the field data collection, model
description, and the model calibration with the additional information necessary to respond to
the questions and comments submitted by the reviewers.
This report combines the original modeling report and the subsequent additional analysis
reports into a comprehensive document. This document includes revisions as necessary to
respond to reviewers' comments.
1.1. Study Scope and Objectives
Applied Technology and Management, Inc. of North Carolina (ATM) performed this study in
support of the permitting and design of the Mason Inlet Relocation Project. The Project will
include the closure of the existing Mason Inlet and the reopening of Mason Inlet
approximately 3,000 feet north of the existing inlet location. The Project will also include the
dredging of Mason Creek to reestablish the creek as a major tributary to Mason Inlet.
The study objective was to develop a hydrodynamic model of Mason Inlet and use the model
to evaluate existing and post-project hydrodynamics and flushing. The results will be used in
the evaluation of the environmental impact of the project and is provided as an addendum to
the Environmental Assessment (EA) prepared for the proposed project. The model results
will also be used to support the engineering design of the inlet relocation project.
The scope of this study includes the following:
• Collection of field data (i.e., current, flow, and water surface elevation measurements,
and hydrographic surveys) necessary to accurately apply and calibrate the
hydrodynamic model
Calibration of a two-dimensional hydrodynamic and transport model to the Mason
Inlet system.
• Application of the computer model as a predictive tool to evaluate the hydrodynamics
and flushing of various project alternatives for.the Mason Inlet Relocation Project.
1.2. Project Location
The project is located at Mason Inlet in New Hanover County, North Carolina. The inlet is
bounded by Figure 8 Island to the north and Shell Island to the south (Figure 1-1). Banks
Channel and Mason Creek connect Mason Inlet to the Intracoastal Waterway (ICWW).
Extensive details describing the project location are provided in Section 2 of the EA
document.
1.3. Report Outline
Section 2 of this report will provide a description of the field data collection effort performed to
provide the data necessary to calibrate the model. Section 3 will provide a technical
description of the WQMAP hydrodynamic and transport model used for the study. Section 4
will describe the model set-up and data input to the model. Section 5 will present the model
calibration process and discuss the model calibration results. Section 6 will present the
various project design alternatives modeled in the first report (ATM, 1999a) and in the
subsequent modeling reports (ATM, 1999b; ATM, 2000). Section 7 will present the additional
analysis performed in the two later reports (ATM, 1999b; ATM, 2000). Section 8 will present
the model study summary and conclusions.
2
Figure 1-1
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2. DATA COLLECTION
Data collection is a critical part of the modeling process and necessary for model calibration
and simulation. For the hydrodynamic model, water surface elevations and discharge are
used to calibrate the model before using it as a predictive tool. Water surface elevation
comparisons identify the model performance relative to the progression of the tidal wave.
Discharge comparisons identify that the model is accurately simulating the tidal prism that
passes through the system, its magnitude and distribution. As the mixing of constituents
discharged into a coastal estuary is directly proportional to the time dependent passage of
water volume and turbulence, accurate simulation of the time dependent nature of the tidal
prism is critical
Field data collection for the project occurred during the summer of 1999. This field effort
included: the deployment of eight YSI instruments which measured water surface elevation,
dissolved oxygen, salinity and temperature; the measurement of current velocities and flow at
eight transect locations; and hydrographic surveys of Mason Inlet, Banks Channel and the
ICWW. The following sections detail the methodology and results of the field data collection.
2.1. Tidal Data
The tide gauges were placed the eight strategic locations in shown in Figure 2-1. These
gauges have a pressure transducer located at the bottom of the instrument that records the
pressure head at user specified time intervals. The gages also measured water temperature,
salinity and dissolved oxygen (DO). The instruments were in operation from June 30, 1999 to
July 30, 1999 and were programmed to record data every 5 minutes. The instrument
specifications and locations are presented in Table 2-1.
• Table 2-1 Instrument Specifications and Locations
'I Instrument Model and Channel Marker/ Identification Instrument Location Name Manufacturer
II
YSI 01 YSI 6000 Marker G-1
YSI 02 YSI 6000 Jetted pipe on bottom
YSI 03 YSI 6000 Jetted pipe on bottom
YSI 04 YSI 6000 Marker R-134
YSI 05 YSI 6000 NW of bridge on 2-piling
dolphin
YSI 06 YSI 6000 Marker G-123
YSI 07 YSI 6000 West fender of bridge
YSI 08 YSI 6000 Marker G-105
Masonboro Inlet
Mason Inlet
Rich Inlet
ICWW south of Masonboro
Inlet
ICWW at Wrightsville Beach
Bridge
ICWW near Howe Creek
ICWW at Figure 8 Island
Bridge
ICWW north of Rich Inlet
The continuous water surface elevation data was measured relative to each instrument's
location in the water column. Since the water surface elevation reading is measured at the
3
instrument bottom (transducer) and the instrument's depth vanes at each location, it is
important to analyze the data in a consistent reference. The first step was to remove the
mean value of each data set by taking an average of the local (instrument specific) data and
subtracting it from all of the data points. This produced a continuous data set for all five
instruments with a mean tide range value of 0.0. The data the was then adjusted to
approximate the National Geodetic Vertical Datum (NGVD), or Mean Sea Level of 1929, by
adding an adjustment of 0.09 ft (based on the National Ocean Service tidal bench mark at
Wilmington Beach). This is not an exact representation of water surface elevations relative to
NGVD (due to the limited nature of the measured data), but it provides a useful base datum
of reference for this project.
The YSI instruments recorded the water elevations for various periods between June 30,
1999 and July 30, 1999. Due to mechanical failure of the instruments, there are gaps in the
data record at most tide station locations. However, adequate data was collected to properly
develop tidal forcings for the model open boundaries and calibrate the model.
2.2. Flow Data
Flow measurements were recorded with an Acoustic Doppler Current Profiler (ADCP)
instrument at eight transect locations (Figure 2-2). The instrument was used between July 14
and July 29, 1999 to measure flow rate, cross-sectional area, velocity profiles, and depths.
Each transect was measured on multiple days to capture the flows at various tidal phases.
Transect locations were selected to capture the flow dynamics present in the study area for
use in model calibration. The transect locations are described in Table 2-2.
• Table 2-2 ADCP Transect Locations
Transect Identification
ADCP 01
ADCP 02
ADCP 03
Location
Masonboro Inlet
ICWW north of Masonboro Inlet
Mason Inlet
ADCP 04 Banks Channel
ADCP 05 ICWW north of confluence with Banks
Channel
ADCP 06 ICWW south of confluence with Banks
Channel
ADCP 07 Rich Inlet
ADCP 08 ICWW south of Rich Inlet
4
2.3. Hydrographic Data
ATM conducted a hydrographic survey of Mason Inlet in July of 1999. The survey also
included Banks Channel, Mason Creek, and the ICVWV near the confluence of the ICWW
and Mason Creek. The survey was performed using a TrimbleTm real-time kinematic global
positioning system (RTK GPS) in conjunction with a vessel mounted precision fathometer.
The survey equipment was integrated using HypakTM software to provide real-time horizontal
and vertical measurements. The tidal elevations during the survey period were recorded
using a tide staff. The tide staff elevation was established by measuring the staff elevation
relative to a local survey monument. In post-processing, the data were adjusted for the
measured tide elevation and referenced to the National Geodetic Vertical Datum of 1929
(NGVD 29).
5
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3. MODEL DESCRIPTION
The model study used a two-dimensional hydrodynamic model to for the purposes of
predicting the immediate post-project tidal prisms, current velocities and flushing
characteristics for various design alternatives. The two-dimensional model is a vertically
integrated hydrodynamic model, which is appropriate to simulate shallow, well-mixed, tidally
dominated barotropic type systems. Three-dimensional analysis is not necessary to simulate
flows for the (relatively shallow) Mason Inlet and Middle Sound Estuary system.
The model is a hydrodynamic and flushing model only, and was not intended to predict
shoreline morphology following completion of the project construction. A morphological
model that can accurately predict shoreline change at an inlet does not yet exist. At present,
morphological models are being developed, but these models still have large amounts of
error and are not reliable for engineering design purposes.
3.1. Hydrodynamic Model
In order to accurately simulate the complex geometric and bathymetric features of Mason's
Inlet, Richs Inlet, Masonboro Inlet, and the Intracoastal Waterway, ATM chose a boundary-
fitted coordinate, hydrodynamic, and transport model system. This system approach uses
transformation functions such that all domain boundaries are coincident with coordinate lines.
The transformation equations are applied to a user-defined grid of arbitrarily sized
quadrilaterals, mapped to the coastal geometry of the water body in the study area. The
hydrodynamic model and the mass transport model equations are written and solved on the
boundary conforming, transformed grid, using a well-known finite difference solution
technique (Spaulding, 1984; Thompson et al., 1977). The boundary-fitted hydrodynamic and
transport models are contained within the model system called WQMAP (Water Quality
Mapping and Analysis Program).
WQMAP includes a state-of-the-art hydrodynamic model and is an appropriate model to
apply to the Mason Inlet and Middle Sound Estuary system. The WQMAP model has been
applied successfully in many projects around the world, the model has been the subject of
numerous technical papers, and it is a well accepted model by engineering professionals and
scientists within the hydrodynamic modeling community.
The state-of-the-art, boundary-fitted hydrodynamic model (Muin and Spaulding, 1997; Huang
and Spaulding, 1995b; Swanson et aL, 1989) was used to generate tidal elevations and
velocities. A detailed description of the hydrodynamic model is presented in Muin and
Spaulding (1997), which is included in this report as Appendix A. The boundary-fitted model
matches the model coordinates with the shoreline boundaries of the water body, accurately
representing the study area. This system also allows the user to adjust the model grid
resolution as desired. This approach is consistent with the variable geometry and coastal
features of the Masons Inlet system. Model development for the boundary-fitted model
approach has proceeded over the last decade (Spaulding, 1984; Swanson et al., 1989; Muin
and Spaulding, 1997).
The boundary-fitted method uses a set of coupled quasi-linear elliptic transformation
equations to map an arbitrary horizontal multi-connected region from physical space to a
rectangular mesh structure in the transformed horizontal plane (Spaulding, 1984). The
two-dimensional conservation of mass and momentum equations, with approximations
6
suitable for lakes, rivers, and estuaries (Swanson, 1986; Muin, 1993) that form the basis of
the model, are then solved in this transformed space. In addition, an algebraic transformation
is used in the vertical to map the free surface and bottom onto coordinate surfaces.
The basic equations are written in spherical coordinates to allow for accurate representation
of large model areas. The conservation equations for water mass, momentum (in
2 dimensions), and constituent mass, form the basis of the model. It is assumed that the flow
is incompressible, that the fluid is in hydrostatic balance, the lateral friction is not significant,
and the Boussinesq approximation applies. The boundary conditions are as follows:
• At land, the normal component of velocity is zero.
• At open boundaries, the free surface elevation must be specified.
• A bottom stress or a no-slip condition can be applied at the bottom.
• No water is assumed to transfer to or from the bottom.
• A wind stress can be applied at the surface.
The set of governing equations with dependent and independent variables transformed from
spherical to curvilinear coordinates, in concert with the boundary conditions, is solved by a
semi-implicit, split-mode finite difference procedure (Swanson, 1986). The equations of
motion are vertically integrated and, through simple algebraic manipulation, are recast in
terms of a single Helmholtz equation in surface elevation. This equation is solved using a
sparse matrix solution technique to predict the spatial distribution of surface elevation for
each grid. The vertically averaged velocity is then determined explicitly using the momentum
equation. A detailed description of the hydrodynamic model and its application is presented in
Appendix A of the Model Report.
3.2. Grid Generator
The WQGRID component of WQMAP was used to generate a boundary fitted grid. The grid
is specified by locating grid points along coastlines and bathymetric features such as
channels and depth contours. Each point has assigned grid indices to keep track of how
each grid point relates to its neighbors. The grid spacing in the domain is roughly determined
by grid spacing at land boundaries. Finer grid resolution is specified for increased flow
resolution. Once the boundary grid points along the shoreline have been specified, and any
bathymetric feature _grid point located, the gridding model generates all the remaining interior
points. These points are constrained to obey a Poisson equation and their locations solved
iteratively by a Poisson solver.
In general the grid aspect ratio reflects a priori estimates of expected flows. This means that
the longer grid dimension, if any, is oriented along the major axis of the flow. This approach
is necessary because the hydrodynamic model has inherent time step restrictions based on
the ratio of grid size to flow speed. Faster model simulations are possible when the grid is
optimized in this manner.
A depth value must be assigned to each grid. Two methods are generally combined to
create the array of grid depths. First, a database of bathymetric soundings with associated
latitude and longitude for the area is accessed. Each grid is automatically assigned a depth
7
value by interpolation from the database based on a distance-weighting algorithm. Once all
grids have depths assigned, the results are shown graphically and may be edited in
WQGRID. The second method is based on the experience of the modeler to more
accurately specify depths. Tools are available to the user in WQGRID to select individual
grids or groups of grids and specify depth values. This procedure becomes necessary when
dredged channels or other bathymetric features are to be accurately represented.
3.3. Marshes
The hydrodynamic portion of the WQMAP modeling system was updated to incorporate the
ability to simulate the inflow and outflow of water and mass to marsh areas that flood and dry
over the tidal cycle. The extensive marsh coverage in the Masons Inlet system plays a key
role in the hydrodynamics. The following presents the formulation of the equations,
assumptions and terms within this model update.
Marsh areas within WQMAP are treated as stand alone storage units connected to the model
domain through small tributary feeder creeks. These creeks are representative of the
geomorphology found within the coastal region of the southeastern United States. At the end
of the creeks, model boundaries are defined similar to existing river inflow boundaries within
the WQMAP modeling system. For each of these marsh boundaries the following physical
parameters are specified:
• Marsh Surface Area
• Front Marsh Elevation
• Back Marsh Elevation
• Manning Coefficient
The front and back marsh elevations are used to allow the marsh to fill gradually; i.e. the
surface area filled is a function of the elevation of the waters entering the creek. This is
typical of coastal marshes that fill through feeder creeks passing through berms along the
edge of the marshes. These berms, which separate the marshes from the main channels,
are generally of a higher elevation than the areas behind them. Therefore, the marshes tend
to fill through the creeks behind the berm areas. The inundated area gradually increases as
the water surface elevation increases. The Manning coefficient is used to quantify the
roughness due to vegetation and the bed surface. The length is defined as the ramp
distance from the tributary feeder bank to the point at which the elevated marsh area is level.
This term plays a role in the sensitivity of the marshes.
To calculate the flow into and out of the marshes two cases are defined. One is where the
elevation in the main channel is above the front marsh elevation. In this case a one-
dimensional simple open channel flow equation is solved of the form:
Qm = 1 /n Aa R2'31 "'
where: Qm = Time rate of inflow/outflow to the marsh,
n = Manning's n value,
8
R = Hydraulic radius of flow area,
= Surface slope between the open water and the boundary cell, and
A, = Cross-sectional area of flow through.
For the case where the water surface elevation in the main channel drops.below the front
elevation of the marsh, the flow is treated as a weir flow and the following equation is solved:
Q. = Cd WL (2g)"2 (Ec _ E J'2
where: Cd = Drag Coefficient (0.577),
WL = Width of the flow,
g = Acceleration of gravity,
Ec = Water surface elevation in the channel, and
ER, = Water surface elevation in the marsh.
The flow into the marsh areas is then adjusted through manipulation of the friction factor
within the flow equation. The surface slope term in each of the equations provides the
feedback. For each time step the flow rate is calculated. The volume of water inside the
marsh is then adjusted by multiplying the inflow rate by the time step. The surface elevation
is then adjusted by the surface area of the inundated marsh.
9
4. MODEL SET-UP
4.1. Model Geometry
The model geometry is defined by the shorelines between Masonboro Inlet and Rich Inlet,
from the Atlantic Ocean to the ICWW. The base shoreline was generated from the National
Ocean Service (NOS) US 1:80,000 shoreline data provided by NOAH. NOS last performed
hydrographic surveys in the study area in 1974. The shoreline in the Mason Inlet, Mason
Creek and Banks Channel area was revised using 1998 rectified digital orthophotos provided
by New Hanover County. Both shoreline boundaries were merged and incorporated into a
WQMAP basemap. The basemap shoreline is shown in Figure 4-1. The digital orthophoto
was also included in the basemap as a georeferenced TIFF image.
The WQGRID program was used to develop the model grid. Figure 4-2 presents the
computational grid used for the model study. The model grid includes Masonboro Inlet,
Mason Inlet, Rich Inlet, the ICWW and the tributaries that connect these four main features.
The two-dimensional grid dimensions are 1=283 cells and J=75 cells. The grid resolution
varies from 30 feet wide in Mason Inlet to 2,000 feet wide at the offshore open water
boundary.
Figure 4-3 presents a detailed view of the model grid near Mason Inlet. The model grid was
overlain on the February 1998 orthophoto to assist the development of the grid in this area of
interest. The orthophoto delineates the low tide flow paths, which are the critical flow paths in
the Mason Inlet area. Although some water flows over the shoals that are emergent at low
tide, a majority of the flow occurs through the main channels which are still flooded during low
tide. Therefore, the error caused by using the low tide flow paths is small and spatially
localized, and alignment of the model grid with the main flow channels present at low tide will
provide good representation of the major flow paths in the system.
Additionally, the use of the low tide flow pathways is adequate for the information sought from
the model study (i.e., maximum current velocities, flow volumes, and flushing analysis).
Since maximum current velocities occur near mid-tide when the flows are channelized, the
use of the low tide grid channels is an appropriate representation. Also, the calibrated model
well represented the flows in the system using the low tide grid.
4.2. Bathymetry
The bathymetry data used for the model included two sources: ATM hydrographic surveys,
and US Army Corps of Engineers (USACE) surveys. -The ATM survey data includes 1999
hydrographic survey data collected at Figure 8 Island, Wrightsville Beach, Mason Inlet,
Mason Creek and Banks Channel. The USACE data includes 1998 hydrographic survey
data in the ICWW and Masonboro Inlet. These data were merged into one data set and
interpolated onto the model grid. Figure 4-4 presents the bathymetry used by the model grid.
Areas that did not have data coverage used a default depth of six feet. However, the flow
volumes in the model are a function of surface area (in the absence of severe hydraulic
restrictions), which is determined by the grid geometry. The default water depth used in
areas lacking bathymetry data does not greatly affect the model flow volumes in the study
area. For example, the model predicted flows through Rich Inlet agree well with measured
values despite the fact that the entire Rich Inlet area uses the default 6-ft depth.
10
The water depth does affect the current velocities; however, these spatial variations do not
affect the flushing characteristics calculated by the model within the primary areas of interest.
In the study areas where current velocities and flushing characteristics were desired and
elsewhere where it was available (i.e., Mason Inlet, Mason Creek, Banks Channel, and the
AIWW) measured bathymetric data were used.
4.3. Marshes
The model set-up was an iterative process that started with only the model grid and without
marsh storage cells. Marsh cells were added incrementally as necessary to increase storage
in the modeled system to achieve the desired flows. Upon completion of the model set-up
and calibration process three groups of marsh cells had been added to increase storage at
Howe Creek, Page's Creek and an area just south of Mason Inlet off the AIWW. The marsh
storage at each cell is based on the estimated marsh surface areas measured from aerial
photographs.
4.4. Tidal Forcing
Boundary conditions are the forcing functions used in the model to drive the circulation.
These time-varying functions can be water levels (tides), flows (river flow), density gradients
(salinity and temperature) and atmospheric effects (winds, temperature, solar radiation).
Not all of the above forcing functions are required for this study of Mason Inlet. Baroclinic
forces are insignificant in a shallow estuary with a large tidal range such as the Mason
Inlet/Middle Sound Estuary.
Except for storms, wind forces are transient and do not significantly effect the flows in the
system. Sustained winds caused by storms may affect the flows in the estuary, but storm
condition model runs were deemed insignificant to the objectives of this study. In terms of the
annual occurrence of conditions that affect the Middle Sound Estuary, storms represent low-
frequency events that that, with a few exceptions such as category 3-5 hurricanes and severe
nor'easters, result in only short- terms fluctuations to the system.
Fresh water input to the system was approximated by multiplying the watershed area
surrounding the estuary by the rainfall produced by a typical storm event. This volume of
fresh water was compared to the volume of salt water that enters the system through the
three inlets. This comparison showed that the fresh water influx to the system is insignificant
compared to the tidal prism in the estuary, and therefore fresh water influx is not required in
the model.
The only forcing necessary for the model application at Mason Inlet is the offshore tidal
forcing. The tides were measured at Masonboro Inlet, Mason Inlet and Rich Inlet to provide
the data required for the tidal forcing of the model.
Water elevation data was recorded for a 30-day period between June 30, 1999 and July 30,
1999. This data collection did not yield complete one-month tide records most of the inlets
due to mechanical failure of the YSI instruments. The number of days collected at each
station ranges from 12 to 29 days, with an average of 21 days. However, enough data was
collected to allow the composition of a continuous tidal record from the tide records at the
three inlets. This continuous tidal record was used as the offshore boundary tidal forcing in
the hydrodynamic model.
11
In a tidally dominated barotrophic system, 14 days of data covering one neap and one spring
tidal condition is appropriate to calibrate a hydrodynamic model; this time span will capture
the spring and neap tidal variations in the system. The period extending from July 14 to July
30, 1999 was selected for the calibration period for the Mason Inlet model. This time period
includes a full spring-neap-spring tidal cycle and includes all of the ADCP field
measurements.
There are gaps in the measured water elevation data during this calibration period.
However, sufficient data records are available to evaluate the model performance through
both the spring and neap conditions.
These calibration simulations were forced using the measured, composite tidal records. The
varying alternative channel design simulations also used the measured, composite tidal
records. The model output for both a spring tide and a neap tide condition were selected to
evaluate the tidal flows and velocities for the various alternative designs. The measured
spring tide amplitude was 5.9 feet, and the measured neap tide amplitude was 2.6 feet.
A comparison of the measured tides used in the evaluation with the NOAA predicted tidal
records shows that the conditions modeled cover most of the range of predicted tidal
conditions. The maximum NOAA predicted tidal amplitude at Masonboro Inlet over the past
19 years (i.e. the last tidal epoch) was 5.8 feet. Therefore the measured tidal amplitude used
slightly exceeds the maximum predicted tidal amplitude (probably due to atmospheric
effects). Additionally, the NOAA predicted tides for the last 19 years show that 95 percent of
the tidal amplitudes will exceed 2.6 feet. Therefore, the measured tides we used for the
model simulations bracket 95 percent of the predicted tidal conditions for the study area.
The model requires a smooth boundary forcing to avoid computational instability. However,
the measured data surface elevation data is not smooth. - The YSI instruments measure the
water elevation very frequently, these data records represent instantaneous "snap-shots" of
the water surface elevation, and do not provide any time averaging. As pressure gage(s) are
placed in the open water and not in a stilling well, all changes in water surface elevations are
recorded, including boat wakes and short-period waves. Therefore, small-scale events (i.e.,
such as boat wakes and wind waves) are present in these data records. These short
duration events do not affect the entire system as these do not propagate through the system
(study area) and are not of interest to this study. A smoothing filter was applied to the data,
and the tidal amplitudes were adjusted for any loss due to the smoothing. The model tidal
forcing and the measured elevations at the inlets are presented Figure 4-5: The time scale of
interest is the semi-diumal tidal cycle, which is the principal influence driving this system.
Therefore, the smoothing of the tidal forcing data does not have an impact on the accuracy of
the model output.
The model was forced by specifying the water surface elevation at the open water
boundaries several thousand feet seaward of each of the three inlets and in the AIWW. The
model computed the flows at the inlets based on the propagation of the tidal wave from the
open water boundaries. The flows calculated at the inlets would be similar whether the
model was forced by separate open water boundaries seaward of each inlet, or the model
was forced by one continuous boundary seaward of the study area.
12
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S. MODEL CALIBRATION
The assessment of the accuracy of numerical models is a complex process. The methodical
application, testing and evaluation of a model to predict field data for a specific study domain
are often referred to as model calibration. The results of this calibration are a good
assessment of the model accuracy. Much literature has been published over the past few
decades describing various approaches (McCutcheon et al., 1990; Hess and Bosley, 1992;
Lynch and Davies, 1995). In general, the calibration process is an organized procedure to
select model coefficients within appropriate ranges for the water body, such that model
predictions produce the best agreement with measured data. The calibration procedure for
the Mason Inlet application included the adjustment of bottom friction to reproduce water
surface elevation and flows at selected locations.
This section describes the calibration coefficients used for the model and the comparison of
the calibrated model with the measured data. The model results are compared graphically
and to normalized root mean square (RMS) error.
5.1. Model Time Step and Friction Coefficient
The model was used to simulate conditions from July 14-29, 1999 with a 24-hour spin-up of
the hydrodynamic forcing. The bottom friction coefficient (Manning's n) was set to 0.03
throughout the model domain. A sensitivity analysis was performed using Manning's
roughness coefficients of 0.06 and 0.015. The results showed that reducing the roughness
by 50 percent (i.e. from 0.03 to 0.015) causes approximately a 7 percent increase in the
maximum flow rate at Mason Inlet. Doubling the coefficient from 0.03 to 0.06 resulted in a 7
percent decrease in the maximum flow rate at Mason Inlet.
The time step used in the model was 75 seconds. The time step for the model was gradually
decreased from 5 minutes until the model stabilized at 75 seconds. After this point, the
solution did not change with decreasing time step, as expected with the semi-implicit solution
technique.
5.2. Model/Data Comparisons
In order to evaluate the model's ability to accurately reproduce the hydrodynamics of the
study area, graphical (qualitative) and statistical (quantitative) analyses were performed. The
graphical analyses include a simple comparison of the plotted measured and simulated water
surface elevations and flows. The quantitative analyses were carried out through the
calculation of the root-mean-squared error (RMS), defined as:
1 2
E= n?(Y,.-y,)
where,
Y = simulated value,
y, = measured value, and
n = number of data points.
13
This RMS error is then normalized by taking E and dividing by the range of the signal, which
the error as a percent of the overall signal strength.
5.2.1. Graphic Comparison of Tides
Figures 5-1 through 5-3 present the graphical comparisons for simulated versus measured
water surface elevations at the eight tide gage locations in the study area. Examination of the
results shows that the model is generally successful at replicating the measured data. The
model is most accurate in representing the tidal elevations at the three inlets (YS101, YS102
and YSI03). The model slightly over predicts the water surface elevations in the ICWW.
Overall, the model well represents the tidal amplitude and phasing throughout the system.
5.2.2. Graphic Comparison of Flows
Figures 5-4 through 5-7 present the graphical comparisons for simulated versus measured
flows at the eight transect locations in the study area. Examination of the results shows that
the model well represents the relative distribution of flows in the study area. The model best
predicts the flows through Masonboro Inlet, the ICWW near Masonboro Inlet and Rich Inlet
(ADCP01, ADCP02 and ADCP07, respectively).
The model calculates greater flow through Mason Inlet (ADCP03) than shown by the
measured data. This is likely due to error in the ADCP measurements. The ADCP
instrument requires a 2-meter depth to function well. A transect cross section with a large
percentage of depths less than 2-meters (e.g., the transect at ADCP03) will cause an under-
estimation of the flow at that transect. The fact that the model results agree well with the
measurements at transect ADCP04 support the conclusion that the model is providing a
better estimate of flow through Mason Inlet than the measured data at Mason Inlet. Also,
when viewed on the same scale as the adjacent inlets, the model seems to be in good
agreement with the measured data. This indicates that the model is successfully
representing the tidal flow distribution in the system as a whole.
5.2.3. Statistical Results
The RMS error was calculated for the measured water surface elevation data since there
were adequate data (i.e., thousands of measurements). However, RMS error analysis is not
appropriate for the measured flows because of the sparseness of the data; many data points
are required for the RMS analysis to be meaningful.
Table 5-1 presents the normalized error results for water surface elevation: The RMS error -
analysis demonstrates the model's ability to simulate the dynamics of the tidal wave
propagation within 5 percent error, with the greatest error occurring at YS106. The error at the
ocean inlets is on the order of 2 to 3 percent, which demonstrates the proper forcing of the
model at the ocean boundaries. The error is slightly higher near the ICWW boundaries (i.e.,
4 to 6 percent). Overall, the model errors are in an acceptable range and the model is able to
capture the tidal dynamics occurring in the system.
5.3. Flushing
Upon completion of the model calibration, the flushing characteristics of the existing
conditions were modeled to provide a comparison for post-project scenarios. The WQMAP
14
model was used to simulate the transport of a conservative tracer (i.e., without considering
any biochemical transformation or settling). An initial tracer concentration of 100 units was
applied to a control volume (a 2-mile stretch of the ICWW centered on Howe Creek). Then,
the model ran a 7-day simulation under neap tide conditions to obtain a conservative
estimate of flushing in the ICWW. Figure 5-8 in the Model Report presents the flushing
simulation results as percent of the initial tracer mass remaining in the control area versus
time. The results indicate that it takes 2.7 days for the tracer mass remaining in the control
volume to diminish to 10 percent of the initial concentration.
• Table 5-1 RMS Error Results for Water Surface Elevations
Location RMS Error
m Normalized
RMS Error
YS101 0.023 0.016
YS102 0.028 0.019
YS 103 0.042 0.030
YS 104 0.057 0.038
YS105 0.049 0.034
YS106 0.096 0.058
YS107 0.080 0.055
YS108 0.076 0.055
Mean RMS Error 0.06 0.04
15

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6. PROJECT ALTERNATIVES ANALYSIS
The model was used to simulate the post-project hydrodynamic conditions at Mason Inlet to
establish the project impacts on the inlet system hydrodynamics and flushing characteristics.
Variations on this design were also modeled to provide insight to the sensitivity of the inlet
system to changes in various project depths and configurations.
The proposed Mason Inlet Relocation Project includes the closure of the existing Mason Inlet
and the opening of a new inlet 3,000 feet north of the existing inlet. The Project also includes
the dredging of Mason Creek and the dredging of a sedimentation basin that is located at the
confluence of the new Mason Inlet cut and Banks Channel. The model grid of the post-
project scenario was created making the following grid changes:
• Deleting the grid cells where the existing Mason Inlet will be filled,
• Creating new grid cells where the new, inlet will be cut and where Mason Creek will be
dredged, and
• Deepening model grid cells where the sedimentation basin will be dredged.
The simulations were run for 17 days from July 13, 1999 to July 30, 1999, which includes a
spring-neap cycle. This yields model results that are representative of typical tidal variations
and conditions within the system on an annual basis. The maximum spring and minimum
neap tidal ranges chosen bracket 95 percent of the tidal variations expected annually within
the estuary.
The various model alternatives were evaluated by four criteria: flow distribution, maximum
current velocity in the inlet throat, maximum current velocity in the sediment basin and
flushing characteristics. The flow distribution was quantified by summing the tidal prisms
passing through Mason Inlet, Mason Creek and Banks Channel. To minimize future inlet
migration, a balance of flow distribution between Mason Creek and Banks Channel is
desirable. Model cells in the center of the inlet and near the center of the sediment basin
were selected for calculating the maximum current velocities. Numerous case studies of
stable inlets have found that the maximum velocity of a stable inlet is generally 1 m/s (±0.1
m/s) (Braun, 1978). Therefore, a maximum current velocity on the order of 3 ft/s is desirable
for the relocated inlet. The sediment basin serves to reduce currents and cause
sedimentation in the basin area, thereby minimizing sedimentation of Mason Creek.
Therefore, the least maximum currentwas desired in the sediment basin.
The flushing impacts to the Middle Sound Estuary were also evaluated for each project
alternative. This was accomplished by comparing the flushing results of each project
alternative with the flushing results for the calibrated model of the existing conditions.
The first twelve model scenarios were conducted for the first modeling report (ATM, 1999a);
these scenarios and results are presented in Section 6.1. Following review of the model
study, several additional model scenarios were analyzed and presented in the later reports
(ATM, 1999b; ATM 2000); these model scenarios are presented in Section 6.2. Table 6-1
summarizes all of the project alternative scenarios modeled in this study.
16
6.1. Initial Alternatives Analysis
This section presents the alternatives analysis performed for the first Mason Inlet model
report completed by ATM (1999a). The October 1999 study included the first twelve model
scenarios presented in Table 6-1. The tidal prisms calculated for each scenario are
summarized in Table 6-2. The spring tide prisms in Table 6-2 were calculated based on the
tides that occurred on July 14, 1999. The neap tide prisms were calculated based on the July
21, 1999 tidal conditions. The maximum current velocities are summarized in Table 6-3.
6.1.1. Scenario 1
The initial recommended project design was modeled in Scenario 1. The recommended
project design has since been revised. Figure 6-1 presents the model grid in the project area
that was used to model the post-project conditions for Scenario 1.
The model predicted a significant increase in the tidal prism that will move through the new
Mason Inlet compared to the existing conditions. The predicted spring tidal prism through the
new Mason Inlet cut is 201 million cubic feet for the July 14, 1999 flood tide and 160 million
cubic feet for the following ebb tide. The model results predict that the relative flow
distribution between Mason Creek and Banks Channel will be 40 percent and 60 percent,
respectively. Therefore, in Scenario 1, Banks Channel will still convey a majority of the tidal
prism to and from Mason Inlet.
The model results show a significant reduction in current velocity between the inlet throat and
the sediment basin: the maximum predicted depth averaged velocity in the new inlet channel
is 2.5 feet per second, and the maximum predicted depth averaged velocity in the center of
the sediment basin is 0.8 feet per second. Therefore, sediments carried through the inlet
throat by high flood current velocities will be deposited in the sediment basin where the
current velocities decrease. This will reduce the shoaling rates of Mason Creek after project
construction.
Figure 6-2 presents the flushing results for Scenario 1 in comparison with the flushing results
for the existing condition. For Scenario 1, the results indicate that it takes 2 days for the
tracer mass remaining in the control volume to diminish to 10 percent of the initial
concentration. In comparison to the 2.7 day flushing time required for the existing conditions,
the proposed project results in a 26 percent decrease in flushing time for the ICWW near
Howe Creek.
6.12- Scenario 2
Scenario 2 varies from the Scenario 1 design by increasing the entrance channel depth to 12
feet and narrowing the entrance channel to a 400-foot width. Figure 6-3 presents the grid
used for Scenario 2.
The predicted tidal prism results for Scenario 2 show no significant change in tidal prism
magnitude or distribution compared to Scenario 1. This is due to the fact that there is little
change in the cross-sectional area of the Mason Inlet throat between Scenarios 1 and 2.
The maximum predicted depth averaged velocity in the new inlet channel is 2.6 feet per
second, which is slightly higher than Scenario 1. Also, the maximum predicted depth
17
averaged velocity in the center of the sediment basin is 0.6 feet per second, which is slightly
lower than Scenario 1.
Figure 6-4 presents the flushing results for Scenario 2 in comparison with the flushing results
for both Scenario 1 and the existing condition. For Scenario 2, the flushing results were
nearly identical to those modeled for Scenario 1.
6.1.3. Scenario 3
Scenario 3 varies from Scenario 1 by decreasing the entrance channel depth to 8 feet.
Figure 6-5 presents the grid used for Scenario 3.
The predicted spring tidal prisms for Scenario 3 are slightly lower than the results for
Scenario 1 because of the reduced cross-sectional area of the inlet throat. The maximum
predicted depth. averaged velocity in the new inlet channel is 3.3 feet per second, which is 32
percent higher than Scenario 1.
Figure 6-6 presents the flushing results for Scenario 3 in comparison with the flushing results
for both Scenario 1 and the existing condition. For Scenario 3, the flushing results were
nearly identical to those modeled for Scenario 1.
6.1 A,. Scenario 4
Scenario 4 varies from Scenario 1 by decreasing the entrance channel depth to 8 feet and
decreasing the entrance width to 400 feet. Figure 6-7 presents the grid used for Scenario 4.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 4 is
approximately 17 percent lower than the results for Scenario 1 because of the reduced cross-
sectional area of the inlet throat. Additionally, the model results predict that Scenario 4 will
produce a relative flow distribution between Mason Creek and Banks Channel is similar to
that shown in Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 3.4 feet per
second, which is 36 percent higher than Scenario 1. Therefore, the model demonstrates that
a reduction in channel depth results in increased current velocities in the channel. The
maximum predicted depth averaged velocity in the center of the sediment basin is 0.8 feet
per second, which is equal to that modeled in Scenario 1.
Figure 6-8 presents the flushing results for Scenario 4 in comparison with the flushing results.
for both Scenario 1 and the existing condition. For Scenario 4, the flushing improvement over
the existing condition was slightly less than that modeled for channel Scenario 1.
6.1.5. Scenario 5
Scenario 5 varies from Scenario 1 by decreasing the entrance channel depth to 8 feet and
increasing the entrance width to 600 feet. Figure 6-9 presents the grid used for Scenario 5.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 5 is slightly
lower than the results for Scenario 1 due to the slightly decreased inlet throat cross-sectional
area. Additionally, the model results predict that Scenario 5 will produce a relative flow
18
distribution between Mason Creek and Banks Channel of 40 percent and 60 percent,
respectively, which is the same as Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.8 feet per
second, which is slightly higher than Scenario 1. The maximum predicted depth averaged
velocity in the center of the sediment basin is 0.8 feet per second, which is equal to that
modeled in Scenario 1.
Figure 6-10 presents the flushing results for Scenario 5 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 5, the flushing results
were very similar to those modeled for Scenario 1.
6.1.6. Scenario 6
Scenario 6 varies from Scenario 1 by increasing the Mason Creek depth to 10 feet. Figure 6-
11 presents the grid used for Scenario 6.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 6 is 10 percent
higher than the results for Scenario 1. Additionally, the model results predict that Scenario 6
will produce a relative flow distribution between Mason Creek and Banks Channel of 48
percent and 52 percent, respectively. This is a more balanced flow distribution than that
modeled for Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.8 feet per
second, and the maximum predicted depth averaged velocity in the center of the sediment
basin is 0.9 feet per second, both of which are slightly higher than that modeled in
Scenario 1.
Figure 6-12 presents the flushing results for Scenario 6 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 6, the flushing results
were slightly improved compared to those modeled for Scenario 1.
6.1.7. Scenario 7
Scenario 7 varies from Scenario 1 by decreasing the Mason Creek depth to 6 feet. Figure 6-
13 presents the grid used for Scenario 7.
The predicted spring tidal prism through the new Mason Inlet cut is slightly lower than the
results for Scenario 1. Additionally, the model results predict that Scenario 7 will produce a
relative flow distribution between Mason Creek and Banks Channel of 32 percent and 68
percent, respectively. This is a less balanced flow distribution than that modeled for
Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.3 feet per
second, and the maximum predicted depth averaged velocity in the center of the sediment
basin is 0.7 feet per second, both of which are slightly lower than that modeled in Scenario 1.
Figure 6-14 presents the flushing results for Scenario 7 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 7, the flushing
improvement over the existing condition was slightly less than that modeled for Scenario 1.
19
6.1.8. Scenario 8
Scenario 8 varies from Scenario 1 by increasing the Mason Creek depth to 10 feet and
increasing the Mason Creek width to 200 feet. Figure 6-15 presents the grid used for
Scenario 8.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 8 is 14 percent
higher than the results for Scenario 1 due to the increased flow capacity of Mason Creek.
Additionally, the model results predict that Scenario 8 will produce a relative flow distribution
between Mason Creek and Banks Channel of 50 percent and 50 percent, respectively. This
is a more balanced flow distribution than that modeled for Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.9 feet per
second, and the maximum predicted depth averaged velocity in the center of the sediment
basin is 1.0 feet per second, both of which are slightly higher than that modeled in
Scenario 1.
Figure 6-16 presents the flushing results for Scenario 8 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 8, the flushing results
were slightly improved compared to those modeled for Scenario 1.
6.1.9. Scenario 9
Scenario 9 varies from Scenario 1 by increasing the Mason Creek width by 30 percent to a
width of 239 feet. Figure 6-17 presents the grid used for Scenario 9.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 9 is 14 percent
higher than the results for Scenario 1 because of the increased flow capacity of Mason
Creek. Additionally, the model results predict that Scenario 9 will produce a relative flow
distribution between Mason Creek and Banks Channel of 50 percent and 50 percent,
respectively. This is a more balanced flow distribution than that modeled for Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.9 feet per
second, and the maximum predicted depth averaged velocity in the center of the sediment
basin is 1.0 feet per second, both of which are slightly higher than that modeled in
Scenario 1.
Figure 6-18 presents the flushing results for Scenario 9 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 9, the flushing results
were slightly improved compared to those modeled for Scenario 1.
6.1.10. Scenario 10
Scenario 10 varies from Scenario 1 by shortening the sediment basin length by 500 feet.
Figure 6-19 presents the grid used for Scenario 10.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 10 is similar to
that for Scenario 1. Additionally, the model results predict that Scenario 10 will produce a
relative flow distribution between Mason Creek and Banks Channel of 38 percent and 62
percent, respectively, which is similar to the results in Scenario 1.
20
The maximum predicted depth averaged velocity in the new inlet channel and in the center of
the sediment basin is equal to that modeled in Scenario 1.
Figure 6-20 presents the flushing results for Scenario 10 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 10, the flushing results
showed no significant changes compared to those modeled for Scenario 1.
6.1.11. Scenario 11
Scenario 11 varies from Scenario 1 by eliminating the sediment basin. Figure 6-21 presents
the grid used for Scenario 11.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 11 is similar to
the results for Scenario 1. Additionally, the model results predict that Scenario 11 will
produce a relative flow distribution between Mason Creek and Banks Channel of 40 percent
and 60 percent, respectively, which is the same as Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.4 feet per
second, which is similar to that modeled in Scenario 1. However, the maximum predicted
depth averaged velocity in the center of the sediment basin is 1.4 feet per second, which is
higher than that modeled in Scenario 1. The absence of the sediment basin is evident by the
increased velocities at the sediment basin location, which will result in increased shoaling
rates of Mason Creek after project construction.
Figure 6-22 presents the flushing results for Scenario 11 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 11, the flushing results
were similar to those modeled for Scenario 1.
6.1.12. Scenario 12
Scenario 12 varies from Scenario 1 by shoaling the depth of Banks Channel to 5 feet. Figure
6-23 presents the grid used for Scenario 12.
The predicted spring tidal prism through the new Mason Inlet cut for Scenario 12 is 14
percent lower than the results for Scenario 1. Additionally, the model results predict that
Scenario 12 will produce a relative flow distribution between Mason Creek and Banks
Channel of 48 percent and 52 percent, respectively, which is a more balanced flow
distribution than that modeled for Scenario 1.
The maximum predicted depth averaged velocity in the new inlet channel is 2.1 feet per
second, and the maximum predicted depth averaged velocity in the center of the sediment
basin is 0.7 feet per second, both of which are slightly lower than that modeled in Scenario 1.
Figure 6-24 presents the flushing results for Scenario 12 in comparison with the flushing
results for both Scenario 1 and the existing condition. For Scenario 12, the flushing
improvement over the existing condition was slightly less than that modeled for Scenario 1.
21
6.1.13. Comparison of Initial Twelve Alternatives Modeled
The first twelve modeled scenarios were completed for the October 1999 report (ATM, 1999),
and the results of the simulations are summarized in Tables 5-2 and 5-3. The results show
that Scenario 1 will significantly improve flushing in the ICWW near Mason Inlet. The
decrease in flushing time is approximately 26 percent.
The project alternatives that produced the largest tidal prisms were Scenarios 6, 8 and 9. All
of these scenarios included enlargement of the Mason Creek cross-section either from
increased depth, increased width, or both. The project alternatives that produced the
smallest tidal prisms were Scenarios 4 and 12, which included the decrease of the entrance
depth and the Banks Channel depth, respectively.
The alternatives that achieved the best flow distributions include Scenarios 8, 9 and 12, which
predicted 50/50 flow distributions between Mason Creek and Banks Channel. Scenarios 8
and 9 caused this by increasing the Mason Creek dimensions and Scenario 12 decreased
the Banks Channel depths.
The project alternative that created the largest entrance channel velocities was Scenario 4,
which decreased the entrance depth and width. Scenario 3 also increased velocities by
decreasing the entrance channel depth.
The project alternatives that resulted in the smallest flushing times were Scenario 8 and 9,
both of which increased the Mason Creek dimensions.
The proposed project design results in an acceptable depreciation in current velocities in the
sediment basin area (Figure 6-25). However, the project alternative that eliminates the
sediment basin (Scenario 11) does not adequately slow the, currents on the estuary side of
the inlet throat (Figure 6-26). This may result in the premature shoaling of Mason Creek.
6.2. Additional Alternatives Analysis
To respond to comments by reviewers and to further evaluate alternative project designs,
several additional model scenarios were evaluated (ATM 1999b, ATM 2000). The additional
model scenarios presented in this report include:
¦ Closure of Mason Inlet (Scenario 13),
¦ Mason Inlet without projects migrated south after 5 years (Scenario 14) and after 10 years
(Scenario 15),
¦ Banks Channel shoaled to a depth of 4 ft (Scenario 16);
¦ Mason Creek narrower (140 feet wide) and deeper (-10 ft NGVD) (Scenario 17);
¦ Sediment basin extended north of the new inlet cut and shortened on the south side of
the new inlet cut (Scenario 18);

¦ Mason Creek narrower (140 feet wide) and deeper (-10 ft NGVD); sediment basin
extended north of the new inlet cut and shortened on the south side of the new inlet cut
(Scenario 19); and
¦ Inlet relocation with no dredging of Mason Creek (Scenario 20).
The results of the additional model scenarios are reviewed in the following sections.
6.2.1. Closure of Mason Inlet
The closure of Mason Inlet was modeled by using the calibrated grid for the existing
conditions and removing the model cells at the opening of Mason Inlet (Scenario 13). The
flushing analysis was performed using the same approach detailed in the model report. The
flushing results show that the inlet closure does not result in a significant change in flushing
rate of the AIWW behind Mason Inlet compared to the existing conditions (Figure 6-27).
However, this scenario will greatly reduce the flushing of Banks Channel. A flushing analysis
of Banks Channel was performed in which Banks Channel was initially flooded with a
conservative tracer. The flushing model results indicate that the closure of Mason Inlet will
result in greatly increased flushing times of Banks Channel compared to the existing
conditions (Figure 6-28).
6.22- Mason Inlet Migration
Two additional model grids were created to simulate the migration of Mason Inlet after 5 and
10 years (without the proposed project). Scenario 14 is the migration of the inlet 1,750 ft
south (5 years at 350 ft/yr). Scenario 15 is the migration of the inlet 3,500 ft south (10 years
at 350 ft/yr). The results for both scenarios show slightly increased flushing times compared
to the existing conditions (Figures 6-29 and 6-30).
6.2.3. Banks Channel Shoaled to Oft Depth
To create the model grid for Scenario 16, the project grid for Scenario 1 was modified by
decreasing the model depths of Banks Channel to -4 ft NGVD. The resulting tidal prisms and
maximum velocities are presented in Table 6-2 and 6-3, respectively. The results indicate
that the shoaling of Banks Channel to a maximum depth of -4 ft NGVD creates a more
balanced distribution of flows between Mason Creek and Banks Channel than does
Scenario 1. This would reduce the southward migration of Mason Inlet induced by the Banks
Channel flows and result in greater positional stability of Mason Inlet. Also, the smaller tidal
prism through Mason Inlet associated with this scenario results in reduced maximum current
velocities in the inlet throat.
The flushing results for this scenario show decreased flushing times compared to the existing
conditions, but slightly increased flushing times compared to Scenario 1 (Figure 6-31).
6.2.4. Narrower Mason Creek
An alternative with the width of Mason Creek reduced to 140 feet was modeled in
Scenario 17. This alternative will reduce the project impact to spartina marsh along Mason
Creek. To compensate for the lost width, the depth of Mason Creek was increased to -10 ft
NGVD.
23
The resulting tidal prisms and maximum velocities are presented in Table 6-2 and 6-3,
respectively. The distribution of flows and maximum velocities for Scenario 17 are similar to
Scenario 1. Also, Figure 6-32 shows that Scenario 17 results in similar flushing as
Scenario 1. This demonstrates that a narrower and deeper Mason Creek will perform
adequately from a hydraulic standpoint, while minimizing impact to adjacent marshes.
6.2.5. Sediment Basin Shifted North
The USACE Wilmington District suggested that the sediment basin would be more effective if
it were extended to the north of the new inlet cut. An alternative with the sediment basin
extended to the north of the new inlet cut and shortened on the south side of the new inlet cut
was modeled in Scenario 18. Figure 6-33 shows the grid used for-this model scenario.
The resulting current vectors for a peak ebb condition are shown in Figure 6-34. Comparison
with the current vectors for Scenario 1 (Figure 6-35) indicate that the sediment basin north of
the inlet cut is effective in reducing the current velocities in Banks Channel immediately north
of the new inlet cut. This would result in greater positional stability of the new inlet cut.
Additionally, the sediment basin configuration modeled in Scenario 18 will be more effective
in capturing sediments on the flood tide. This sediment basin configuration would intercept
more of the sediments that would be transported into Mason Creek and Banks Channel.
The flushing analysis for Scenario 18 indicates that this sediment basin configuration
produces slightly increased flushing times compared to the sediment basin configuration in
Scenario 1 (Figure 6-36).
6.2.6. Sediment Basin Shifted North and Narrower Mason Creek
Scenario 19 includes the narrower Mason Creek cut (140 ft wide) and the sediment basin
shifted north. However, because the north end of the sediment basin modeled in
Scenario 18 would impact spartina marsh, the sediment basin in Scenario 19 was not shifted
as far north. The model grid for Scenario 19 is shown in Figure 6-37.
The results for Scenario 19 show a maximum velocity of 2.7 ft/s in the inlet throat. This is
close to the 3 ft/s maximum velocity generally observed in stable inlets. If the maximum
velocity is not great enough to maintain the inlet cross-section, some post-construction
adjustment may occur. Based on the results of Scenario 3, where the decreased entrance
depth of 8 ft resulted in a 3.3 ft/s maximum velocity, the inlet would not require a great
adjustment to increase the maximum velocity to 3 ft/s.
Figure 6-38 shows that the north end of this sediment basin design is effective at decelerating
the currents flowing out of Banks Channel during the maximum ebb flow. The flow
distribution between Mason Creek and Banks Channel is about a 41:59 ratio, which is slightly
better than Scenario 1. This configuration will direct less of the flow through Mason Creek
than desired from an engineering perspective (i.e., a 50:50 split), but it is the best possible
scenario while avoiding undesirable environmental impacts.
The flushing analysis for Scenario 19 indicates that this sediment basin configuration
produces similar flushing times compared to the sediment basin configuration in Scenario 1
(Figure 6-39).
24
Since this scenario will perform adequately from a hydraulic standpoint and the scenario will
minimize marsh impacts along the Mason Creek cut and avoid marsh impacts at the north
end of the sediment basin, Scenario 19 was identified as the new preferred project
alternative.
6.2.7. No Dredging in Mason Creek
Scenario 20 represents the project construction without dredging Mason Creek. The model
grid for this project configuration was created by deleting the Mason Creek grid cells from the
Scenario 19 grid (Figure 6-40).
The results for Scenario 20 show that the post-project tidal prism passing through Mason
Inlet will be approximately 27 percent smaller than that expected for Scenario 1. This
decreased tidal prism produces smaller maximum current velocities in the inlet throat (i.e., 1.8
ft/s). Therefore, the project that excludes the'dredging of Mason Creek would necessitate a
reduction in the Mason Inlet design cross section to provide for the velocities necessary for a
stable inlet cross section. The flushing analysis shows that this scenario would provide little
change in flushing of the AIWW compared to the existing conditions (Figure 6-41).
This project alternative does not fulfill the goal of creating a more balanced distribution of
flows between Mason Creek and Banks Channel. This alternative is not expected to
increase the horizontal stability of Mason Inlet, and post-project inlet migration rates on the
order of 350 ft per year (i.e., the historic migration rate following the infilling of Mason Creek)
would be expected. Therefore, this is not a desirable project alternative.
25
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Distribution for Modeled Project Scenarios

S
i
Tid Tidal Prism (million cubic feet) Percent of Flow
Distribution
cenar
o e
New Mason
Inlet
Mason
Creek
Banks
Channel
Mason
Creek
Banks
Channel
1 Spring - Flood -201 -70 -120 37 63
Spring - Ebb 160 59 88 40 60
Neap - Flood -98 -35 -56 38 62
Neap- Ebb 96 35 53 40 60
2 Spring - Flood -201 -69 -121 36 64
Spring - Ebb 161 59 88 40 60
Neap - Flood -98 -35 -56 38 62
Neap- Ebb 96 35 53 40 60
3 Spring - Flood -192 -65 -114 36 64
Spring - Ebb 152 56 84 40 60
Neap - Flood -92 -33 -53 38 62
Neap- Ebb 90 33 50 40 60
4 Spring - Flood -167 -53 -98 35 65
Spring - Ebb 134 48 74 39 61
Neap - Flood -79 -27 -45 38 63
Neap- Ebb 77 28 44 39 61
5 Spring - Flood -196 -67 -117 36 64
Spring - Ebb 156 57 86 40 60
Neap - Flood -95 -34 -55 38 62
Neap- Ebb 92 34 51 40 60
6 Spring - Flood -220 -91 -117 44 56
Spring - Ebb 176 77 85 48 52
Neap - Flood -109 -47 -54 47 53
Neap- Ebb 106 47 51 48 52
7 Spring - Flood -187 -54 -123 31 69
Spring - Ebb 149 46 91 34 66
Neap - Flood -90 -26 -57 31 69
Neap- Ebb 88 26 54 33 68
8 Spring - Flood -230 -102 -115 47 53
Spring - Ebb 183 86 84 51 49
Neap - Flood -114 -53 -53 50 50
Neap- Ebb 111 52 50 51 49
9 Spring - Flood -231 -104 -115 47 53
Spring - Ebb 183 87 83 51 49
Neap - Flood -114 -53 -53 50 50
Neap- Ebb 110 52 50 51 49
10 Spring - Flood -200 -70 -120 37 63
Spring - Ebb 160 59 88 40 60
Neap - Flood -98 -35 -56 38 62
Neap - Ebb 95 35 53 40 60
27
• Table 6-2 (cont.) Comparison of Predicted Tidal Prism and Flow
Distribution for Modeled Project Scenarios

S
i Tidal Prism (million cubic feet) Percent of Flow
Distribution
cenar
o Tide New Mason
Inlet Mason
Creek Banks
Channel Mason
Creek Banks
Channel
11 Spring - Flood -200 -69 -120 37 63
Spring - Ebb 160 58 88 40 60
Neap - Flood -98 -35 -56 38 62
Neap- Ebb 95 35 53 40 60
12 Spring - Flood -173 -73 -91 45 55
Spring - Ebb 140 61 66 48 52
Neap - Flood -84 -37 -40 48 52
Neap - Ebb 83 37 37 50 50
16 Spring - Flood -160 -75 -78 49 51
Spring - Ebb 131 62 55 53 47 .
Neap - Flood -77 -37 -33 53 47
Neap - Ebb 77 37 30 55 45
17 Spring - Flood -207 -76 -119 39 61
Spring - Ebb 166 64 87 42 58
Neap - Flood -102 -39 -55 41 59
Neap - Ebb 100 39 52 43 57
18 Spring - Flood -200 -64 -106 38 62
Spring - Ebb 160 55 80 41 59
Neap - Flood -97 -32 -51 39 61
Neap - Ebb 94 32 49 40 60
19 Spring - Flood -213 -76 -121 39 61
Spring - Ebb 171 65 88 42 58
Neap - Flood -105 -39 -56 41 59
Neap - Ebb 102 39 52 43 57
20 Spring - Flood .-146 NA -132 NA NA
Spring - Ebb 116 NA 99 NA NA
Neap - Flood -70 NA -61 NA NA
Neap - Ebb 68. NA 59 NA NA
Note: The spring tidal prisms are calculated for the simulated July 14, 1999 conditions and the neap -
tidal prisms are calculated for the simulated July 21, 1999 tidal conditions.
28
• Table 6-3 Comparison of Maximum Predicted Depth Averaged Current
Velocities for Modeled Project Scenarios
Project
Scenario
Alternative Description Maximum
Entrance Channel
Ebb Velocity (ftfs) Maximum Sediment
Basin Flood
Velocity (ft/s)
1 Preferred alternative 2.5 0.8
2 Increase entrance depth, decrease width 2.6 0.6
3 Decrease entrance depth 3.3 0.7
4 Decrease entrance depth, decrease width 3.4 0.8
5 Decrease entrance depth, increase width 2.8 0.8
6 Increase Mason Creek depth 2.8 1.0
7 Decrease Mason Creek depth 2.3 0.7
8 Increase Mason Creek depth and width 2.9 1.0
9 Increase Mason Creek width 30% 2.9 1.0
10 Shorten basin length by 500 ft 2.5 0.8
11 No sediment basin 2.4 1.4

12 Decrease Banks Channel maximum
2.1
0
7
depth to 5 ft .

16 Decrease Banks Channel maximum
1
9
0
7
depth to 4 ft . .

17 Decrease Mason Creek width to 140 ft,
2.6
0
8
increase depth to 10 ft .
18 Shift sediment basin north 2.5 . 1.0
Shift sediment basin north, decrease
19 Mason Creek width to 140 ft and increase 2.7 1.0
depth to 10 ft
20 No Mason Creek dredging 1.8 0.5
29
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OF NORTH CAROLINA, INC.
7. ADDITIONAL MODEL ANALYSIS
In response to comments and suggestions by USACE Wilmington, WES, and Dr. John
Fisher, additional model analysis was done to further evaluate the effects of the project on the
study area. The following evaluations were performed:
¦ Evaluation of the flushing within the sediment basin;
¦ Comparison of measured and simulated tidal prisms;
¦ Evaluation of expected change in tidal dominance at Masonboro Inlet, Mason Inlet, and
Rich Inlet;
¦ Comparison of the pre- and post-project tidal prisms at Masonboro Inlet, Mason Inlet, and
Rich Inlet;
¦ Definition of area of influence of the change in hydraulics expected in the vicinity of
Mason Inlet.
7.1. Flushing of the Sediment Basin
The WQMAP mass transport model was used to evaluate the flushing of the sediment basin
for Scenario 1. This was done by flooding the sediment basin with a conservative tracer and
calculating the percent of the initial mass of the tracer remaining in the sediment basin over
time. As one would expect intuitively, the basin flushes quickly.. The results indicate that
under neap tide conditions, the sediment basin will flush to less than 10 percent of the initial
contaminant mass remaining within 5 hours (Figure 7-1).
7.2. Comparison of Measured and Simulated Tidal Prisms
The mixed tides at Mason Inlet cause the tidal prism to fluctuate significantly from one tide to
the next. Therefore, it is important to use the exact same tidal conditions when comparing
tidal prisms calculated from ADCP field measurements and tidal prisms calculated by the
hydrodynamic model.
ADCP. measurements were performed at Mason Inlet by ATM on February 10, 1998, and
July 15, 22, and 28, 1999. The tidal prisms were calculated using these flow measurements
and are presented in Table 7-1. The tidal prisms calculated from the hydrodynamic model _
output for the same tidal forcing are also included in Table 7-1.
The flow through Mason Inlet was measured using two ADCP transects: one in the inlet
throat (ADCP03) and one in Banks Channel (ADCP04). The flow at transect ADCP03 should
be significantly greater than the flow at transect ADCP04 since there is significant storage
area between these two transect locations. A comparison of the data measured at these two
transects in Table 7-1 shows that the prism measured at ADCP03 is not significantly greater
and is even less than the prism measured at transect ADCP04. This is the result of error in
the ADCP measurements at transect ADCP03. The ADCP instrument requires a 2-meter
depth to function well. A transect cross section with a large percentage of depths less than 2-
30
meters (e.g., the transect at ADCP03) will cause an under-estimation of the flow at that
transect.
ADCP measurements are more reliable for well-defined cross-sections. The cross-section at
transect ADCP04 in Banks Channel is better suited for accurate ADCP measurements than
Mason Inlet. A comparison of the tidal prisms based on ADCP measurements with the tidal
prisms based on the model output shows that they are in the same range.
Considering the fact that the model and ADCP tidal prisms for Banks Channel are in the
same range, the tidal prism at Mason Inlet calculated from the model results should also be in
the proper range.
7.3. Expected Change in Tidal Characteristics
Additional analysis was performed to examine the change in the tidal characteristics (i.e., tidal
dominance and tidal prism) of Masonboro Inlet, Mason Inlet, and Rich Inlet expected from the
project construction. Establishment of tidal dominance at the inlets using measured data is
difficult because of the mixed tides. In this mixed-tidal environment, a flood tide and the
subsequent ebb tide rarely have the same elevation range, and therefore, their tidal prisms
are not directly comparable for the purposes of determining tidal dominance. Therefore, the
analysis was simplified by using the model simulating an M2 semi-diumal tide cycle. The
simulations were run with a 4.8 ft tidal range, which is the range associated with the Mean
High Water Spring (MHWS) established by NOAA at Masonboro Inlet. The Scenario 19
model grid was used to represent the post-project conditions.
The model results also predict that the tidal prism at Mason Inlet will increase approximately
150 percent. This may change as the inlet cross-section adjusts following construction. The
project also results in slight reduction of the tidal prism at Masonboro and Rich Inlets (by 3
percent and 5 percent, respectively). This change in tidal prism should not have a significant
effect on the inlet dynamics at these inlets. The tidal prisms are summed for the three inlets
in Table 7-2. The model predicts that the project will result in a slight increase (i.e., 4 percent)
in total tidal flux through the three inlets.
7.4. Expected Area of Influence of Change in Hydraulics
The project construction will cause significant changes in the inlet hydraulics at Mason Inlet.
Examination of the simulated post-project tidal prisms at Masonboro and Rich Inlets shows
that the expected changes in hydraulics at the adjacent inlets are expected to be small. This
section will further evaluate the expected changes throughout the system by examining
changes in tidal elevation and current speed throughout the modeled area.
The model results for the post-project conditions (Scenario 19) were compared to the
simulated existing conditions at selected time-series locations throughout the model domain.
These time-series locations output current velocity and surface elevation at a user-specified
time-step. To evaluate the area of influence of the project impacts, three pre- and post-
project comparisons were used: change in surface elevation at high tide, change in surface
elevation at mid-ebb tide, and change in current magnitude at mid-ebb tide.
Figures 7-2, 7-3 and 7-4 show the simulated changes in high tide surface elevations, mid-ebb
tide surface elevations and mid-ebb tide current magnitude resulting from the project
construction. As one would expect, the greatest changes occur at the new channel
31
construction location. The changes diminish along Banks Channel out to the AIWW. The
changes become small towards the adjacent inlets and the domain boundaries on the AIWW.
Since the changes do not go to zero inside the model domain (except for the high tide
elevation comparison) an area of influence is not easily delineated. However, it can be
expected that significant changes will occur near Mason Inlet, in Banks Channel and in the
AIWW behind Mason Inlet. Away from these areas, the expected changes are small.
7.5. Changes in Flow in the Vicinity of Mason Inlet
The results of the M2 tide model run for Scenario 19 were analyzed by inspecting the flows at
the three inlets and at four other transects in the Mason Inlet vicinity. The transects were
located in Banks Channel (at ADCP04), in the AIWW north of the confluence with Banks
Channel (ADCP06), in the AIWW south of the confluence with Banks Channel (ADCP05),
and in the AIWW south of the confluence with Mason Creek. The transect locations are
shown in Figure 7-5.
The flow rates were calculated hourly through an M2 spring tide cycle and compared for the
pre- and post-project simulated conditions (Tables 7-3 and 7-4). The flow rates in Table 7-3
show a large increase (139 percent) in the maximum flow rates at the relocated Mason Inlet,
as expected. The table also shows only very small decreases in the flow rates at the
adjacent inlets.
Table 7-4 shows an approximate 70 percent increase in the peak flow rates through Banks
Channel. The results also show a small increase in the peak flows in the AIWW south of
Banks Channel, and there are small decreases in peak flows in the AIWW north of Banks
Channel and south of Mason Creek. These data support the conclusion that the increase in
flow through Mason Creek and Banks Channel due to the project construction is mostly
limited in its effects to the region including Banks Channel, Mason Creek, and the AIWW
directly behind Banks Channel and Mason Creek. The additional flow results in increased
tidal amplitude in this limited area (as demonstrated by the plot of high tide elevations in
Figure 7-2). Outside of this region, the impacts due to the project construction are expected
to be small.
32
• Table 7-1 Comparison of tidal prism calculated from ADCP flow measurements
and from the hydrodynamic model output

Location
Date Tidal
Range
(ft) Tide
Direction TidalADPrism CP from
Measurments
10x6 ft"3 - Tidal Prism
from Model
(10x6 ft" 3)
Transect 2 - Mason 10-Feb-98 4.2 Ebb 73
1
Inlet .
Transect 2 - Mason 10-Feb-98 3.7 Flood 33
6
Inlet .
ADCP03 - Mason 15-Jul-99 4.2 Ebb 18
6 54
6
Inlet . .
ADCP03 - Mason 22-Jul-99 3.4 Flood 25
4 54
0
Inlet . .
ADCP03 - Mason 28-Jul-99 3.4 Ebb 23
7 47
5
Inlet . .
ADCP04 - Banks 15-Jul-99 4.2 Ebb 27
4 26
0
Channel . .
ADCP04 - Banks 22-Jul-99 4
3 Flood 25
1 31
7
Channel . . .
ADCP04 - Banks 28-Jul-99 3.4 Ebb 20
1 24
0
Channel . .
• Table 7-2 Simulated tidal prisms for an M2 spring tide (in millions of cubic feet)
Location Tidal Prism 1x106 ft3 Tidal Dominance
Flood Ebb
Pre- ro'ect
Masonboro Inlet -706 721 Slightly ebb
Mason Inlet -66 58 Slightly flood
Rich Inlet -557 433 Flood
Total -1330 1213
Post= ro'ect
Masonboro Inlet -684 697 Slightly ebb
Mason Inlet .-164 150 Slightly flood
Rich Inlet -532 410 Flood
. Total -1380 1256
33
• Table 7-3 Pre- and post-project flow rates in Masonboro Inlet,
Mason Inlet and Rich Inlet during an M2 spring tidal cycle
Time Flow Rate (cfs)
(hours) Masonboro Inlet Mason Inlet Rich Inlet (ADCP07)
(ADCP01)
Pre-project Conditions
0 20581 287 -10782
1 42682 3011 15198
2 46679 4255 33434
3 42946 3862 30617
4 30747 2682 22251
5 14111 1565 13999
6 -7809 313 5976
7 -24841 -1613 -8646
8 -37214 -2873 -22104
9 -46097 -4293 -32969
10 -45677 -4763 -37352
11 -31664 -3728 -32451
12 607 -1199 -18824
Post-project Conditions
0 19953 629 -10668
1 41530 6533 14092
2 45087 10077 31859
3 41123 10189 29044
4 29814 7930 21224
5 13513 4826 13349
6 -8629 422 5620
7 -24216 -4875 -8024
8 -35848 -8150 -21307
9 -44532 -10916 -31550
10 -44171 -10989 -35400
11 -30153 -7938 -30725
12 823 -2419 -18119
34
• Table 7-4 Pre- and post-project flow rates in the vicinity of Mason Inlet
during an M2 spring tidal cycle
Flow R ate (cfs)
Time Banks AIWW south AIWW north
(hours) Channel of Banks of Banks AIWW south o
(ADCP04) Channel Channel Mason Creek
(ADCP05) (ADCP06)
Pre-project Conditions
0 693 6338 7260 6334
1 -1136 4787 5408 4332
2 -2306 1672 2118 1101
3 -2041 -1230 -2724 -3727
4 -1501 -3175 -5423 -6026
5 -902 -4103 -6345 -6479
6 -190 -4558 -5950 -5395
7 761 -4663 -4310 -3001
8 1378 -3796 -3202 -1747
9 1868 -963 1131 2649
10 2288 3045 5221 6029
11 2218 5878 7817 7728
12 1361 6647 7954 7170
Post-project Conditions
0 911 6069 6523 5977
1 -1494 3521 4238 5920
2 -3513 -488 905 3843
3 -3534 -3635 -3802 -677
4 -2768 -4936 -5966 -3308
5 -1774 -5256 -6512 -4645
6 -522 -4942 -5629 -4885
7 1301 -3756 -3772 -4442
8 2551 -2121 -2626 -4397
9 3582 1508 1864 -927
10 3898 5383 6050 2615
11 3280 7312 8078 4832
12 1767 6895 7550 5801
35
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OF NORTH CAROLINA, INC.

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APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA, INC.
8. CONCLUSIONS
This report summarizes the hydrodynamic and flushing modeling performed to determine the
changes in hydraulics and flushing expected from the Mason Inlet Relocation Project. The
report includes the information from the initial modeling report (ATM, 1999a) as well as the
information from subsequent reports that presented additional modeling and analysis (ATM,
1999b; ATM 2000).
The results of the hydrodynamic and flushing model simulations support the following
conclusions:
• The relocated inlet will generate sufficient current velocities (i.e., 2.7 ft/s for Scenario 19)
to scour deposited sediments from the inlet gorge and maintain the inlet cross-section.
• The inlet relocation will significantly increase flushing of the AIWW in the region near
Mason Inlet.
The additional alternatives simulations determined the following:
• A narrower and deeper Mason Creek configuration will both minimize marsh impacts and
perform adequately from a hydraulic standpoint;
• Shifting the sediment basin northward will reduce the currents in Banks Channel before
reaching the new inlet throat, and should also be more effective in trapping sediments;
• Both of these elements should be incorporated into the preferred alternative design.
The additional modeling analysis also support the following conclusions:
• The sediment basin is expected to flush quickly during neap tide conditions;
• The project construction is expected to significantly increase the Mason Inlet tidal prism
(i.e., 150 percent at spring tide), but changes at the adjacent inlets are expected to be
small (5 percent or less);
• The project is not expected to change tidal dominance at Masonboro, Mason or Rich
Inlets;
• Significant changes to the hydraulics of the system are expected to be limited to Mason
Inlet, Banks Channel, Mason Creek and the AIWW directly behind Banks Channel and
Mason Creek.
36
9. REFERENCES
Applied Technology and Management, Inc., 1999a. "Hydrodynamic Modeling of Mason Inlet
and the Middle Sound Estuary, New Hanover County, North Carolina" Engineering report
prepared for New Hanover County. October, 1999.
Applied Technology and Management, Inc., 1999b. "Additional Hydrodynamic and Flushing
Model Scenarios - Mason Inlet Relocation Project." Engineering report prepared for New
Hanover County. Submitted as an addendum to the Mason Inlet Relocation Project
Environmental Assessment. December, 2000.
Applied Technology and Management, Inc., 2000. "Additional Hydrodynamic and Flushing
Model Scenarios - Mason Inlet Relocation Project." Engineering report prepared for New
Hanover County. Submitted as an addendum to the Mason Inlet Relocation Project
Environmental Assessment. April, 2000.
Bruun, P., 1978. "The Stability of Tidal Inlets, Theory and Engineering." Elsevier, Amsterdam,
New York. Coauthors: A.J. Mehta -'Tidal Hydraulics" and I.G. Jonsson - "Combinations
of Waves and Currents."
Hess, K.W. and KT Bosley, 1992. Methodology for validation of a Tampa Bay Circulation
model. Proceedings of the 2nd International Conference on Estuarine and Coastal
Modeling. Tampa, Florida. November 13-15,1991. pp 83-95.
Huang, W. and M. Spaulding, 1995a. Modeling of CSO-induced pollutant transport in Mt.
Hope Bay. ASCE J. of Environmental Engineering, Vol. 121, No. 7, July, 1995, 492-498.
Huang, W. and M. L. Spaulding, 1995b. A three dimensional numerical model of,estuarine
circulation and water quality induced by surface discharges. ASCE Journal of Hydraulic
Engineering, 121: (4) April 1995, pp. 300-311.
Lynch, D.R. and A.M. Davies, 1995. Quantitative skill assessment for coastal ocean models.
Coastal and Estuarine Studies. No. 47, American Geophysical Union. Washington, D.C.
McCutcheon, S.C., Z. Dongwei, and S. Bird, 1990. Model calibration, validation, and use,
Chapter 5 in Technical Guidance Manual for Performing Waste Load Allocations, Book
III: Estuaries, Part 2: Application of estuarine waste load allocation models, Edited by J.
J. Martin, R.B. Ambrose, and S.C. McCutcheon,,US Environmental 'Protection Agency,
Office of Water, March 1990.
Muin, M. 1993. A three-dimensional boundary fitted circulation model in spherical
coordinates. Journal of Hydraulic Engineering. ASCE. 122(9). Pp 515-521.
Muin, M. and M.L. Spaulding. 1997. Three-dimensional boundary-fitted circulation model.
Journal of Hydraulic Engineering. ASCE. January 1997. pp2-212.
Spaulding, J.L. 1984. A vertically averaged circulation model using boundary-fitted
coordinates. Journal of Physical Oceanography, 14. pp 973-982.
Swanson, J.C. 1986. A three-dimensional numerical model system of coastal circulation and
water quality. PhD dissertation. University of Rhode Island, Kingston, Rhode Island.
37
Swanson, J.C., Mendelsohn, D., Rines, H., and Schuttenberg, H., 1998. Mt. Hope Bay
hydrodynamic model calibration and confirmation. Prepared for: New England Power
Company, West Borough, MA, prepared by Applied Science Associates, Inc.,
Narragansett, RI.
Thompson, J.F., F.C. Thames and C.W. Mastin. 1977. TOMCAT - A code for numerical
generation of boundary-fitted curvilinear coordinate systems on fields. containing any
number of arbitrary two-dimensional bodies. J. Comput. Phys. 24, pp 274-302.

Appendix A
MUIN, M. AND SPAULDING, M. L. (1997)
THREE-DuvmNsioNAL BouNDARY-FrrrED CIRCULAUON MODEL
By Muslim Muinn and Malcolm Spaulding'
AesT =r- A spherical eoorrdmate, nonottbogonal, boundary-fitted, circulation model (con-
travarant formulation) for application to estuarine. coastal sea, and continental shelf" waters is presented. The
model cmPloys a split mode Wdmgrte wbm the equations am decomposed 'iota exterior and interior modes,
The exterior mode (vertically averaged) described in an earlier paper (Main and Spaulding 1996), is solved using
A Stfa implicit solution ttx mkM, The interior me& (vedcal strnc w) Is solved explicitly, awept for the vertical
diffusion terms that act: solved implicitly. The temporally athd spatially varying eddy viscosity and dillUsivity
are determined fi+om a turbulent ldaedc energy eguanon, and on empirically specified length scale. A series of
tests are presented to evehaft model petfotmance v4mo analytical solutions or other exical solutions art
available for comparison. The model's altility to podia the plant vatical structuve of tidal flow is tested against
analytic solutions employing (1) constam vis jr; and (2) an eddy viscosity varying linearly with depth with
a no-slip, bottom boundary ct nftion. The ability of dire model to simalow turn-dimeaslortal tidal flow was
tested against an exact solution for on annular section clzoand wide qua4kadcatly varying bathymeory, The model
was also tested against analytic sotud= for seedy residual Bow generated by density gnrdl«u, wind, and river
flow In a channel. The model predicted turbuloa amV dis tiom Senerated f a bottom boundary were
emend to those from a previous numerical st r by Davies and kwas (1990).. No4lip and bottom stress
foonWations at the sea bed, and their of act on the vortical stmeture of the dow am analyzed. The model was
used to predict the salinity &gtr&jdom in a simple rectattgalw Wm*d to do Rotterdam Wherwway.
The computmotW method is very economical, stable, and accurate vvith,tlne CFL stability eandition up to 100.
INMOUC TION
Numerical Ming techt ues art routinely used to study
oitovlation and pollutant transport m emrsutihte and coastal we,-
errs. The tnvority of models employ finde-difference arch-
nkm on squat gdd systems. Wlak this has proven
inn various vplicafic? it becomes ctponsive when die study
region is geometrically and bathymebicdly compicx. Such
aff culties motivate the use of aiterttadve'solution approaches
that allow flexib£Iity in the grid spoci&caatiomt, for example f1-
nice elements (Lynch and Werner 1983) and boundary-fitted
coordinates; (Johnson 1986. Spaulding 1984; Sheng 1986;
Swanson 1986, Muin and Spaulding 1995).
This paper presents the cue nsioan of a two-?iemal (213)
vertically averaged. bounndary fillet!, spbodcal coordinate, cir-
culation model developed by Muitt and Spaulding (19916) to
three dimensions. The paper first presetts the governing e qua-
dons is spherical coordinates with appropriate Mans
and boundary conditions. The equations are further bans-
formed to a ecuordilnate. This is followed by ptaatctths of
the governing equations in a generalized tmttrfliaeartxn w4 hu to
system, turbtnkaw parfrmdarization, the solution mm adwdol-
ogy, and model testing for which analytic (Bremer problmus)
solutions or other num ricol solutions are read[W avallabk.
IU09 emphasues calculations of the vertical structum of the
Bow. Testing of the ZD vertically averaged version of the
model for a series of horizontal flow problems (see Lynch and
Gray 1938) was presented in Muin and Spaulding (19961.
GOVERNING EQUATIONS
Using a spherical coordinate system, whore + = lon71giuWe
positive east; 6 = latitude positive north; and r = positive up,
`Jurusan Teknitr Sipil, Institut Tetwologi Bandung, Bandung. Indoae-
'Prof. and Chair. Dept, of Oc. Engrg., Unix of Rhode Island, Narra-
gansett Say Campus, Narragansea, III 02882...
Note. Discussion open until June 1, 1997. Separi to discussions should
be submittal for the individual papers in this symposium. To extend the
closing date one month, a written, request must be filed with the ASCE
Manager of Journals. The manuscript for this pares was submitted for
review amt possible publication on January 1% 1994. This paper is part
of the Journd of 8ydr,>, utte EngWAIng. Vol. 123. No. 1. January, 1997.
OASCE, ISSN 0733-9429/97/ODDI-OOM-Ool2tS4.00 + 5.50 per page.
Paper No. 7655.
the equations of contiaprttity, momentum and conservation of
substance can be written as
Ctmtlrtu ty
1 etc l av v 1' ar?w
r esat$il+ 7 -ae ,.-r- tan S +r_ -ar-- _ © . (1)
s? r ti .
Momentum
won
u u at u arc xv au w
+ +- -tang+w-+ tc--fu
a: r cos 8 a? r as i t err r
_ 1 ap } a
pr cos 8 adr +Sr (A- a ai<r) (2)
8-motion
av a av a at, au vw
er+rexxm8 +?'-?+-tan8+w-+--+fu
a? r ere r ar r
--1-.- op- + a (A. iv-)
p ,r an 8 e,0 Or err (3)
r-dir e'doll
_ -pg (4)
?Canselrvatmomt of Substarme tag)]
I+rcos0a++lae waar=dr D. t}r!
_
1)A ate ., a2q
+ r' ?20a,0: + a8x (5)
Equation of !State of Sea Water
P =I(S e) (6)
where t - tithe; u, v and w = velocity components in 46, 0. and
r ditectiotas„ respectively; f Coriolis parameter. p = pressurt;
g = gravity; p = water density; P. = basin-averaged water den-
sity; A. = vertical eddy viscosity; D, = vertical eddy diffusiv-
I IrN410MAInc uvnQA1It Ir %=N(''INFERING /JANUARY 1997
ity; D. = horizontal eddy diffusivirr; @ = temperature °C; S =
salinity (ppt); and 4 = concentration of a conservative sub-
stawx: such as 49 or S.
Tbo equations described previously assume the following:
the flow is incompressible, density differences am neglected
.Wrnkss multiplied by gravity (Boussinasq approximadon). the
vertical acceleration is very small compared to gravity (hydro-
static assumption), and the horizontal stresses are glccted•
Boundary Condlttorts
The land boundaries are as macd impermeable where the
normal component of velocity is set to zera
V• n : o t"7)
on river boundaries, the velocities are specified stud at pros-
we gradient is set to zero. At open boundaries the water el-
evation or vertically vasying velocity as a function of time is
known hom field observations or adierwise specified.
At dosed boundaries the ttomport of substance is :moo. At
an vgcn boundary the ooncentradca, must be specified daring
inflow on outflow the substance is acivected out of the rtrodel
domain according to
aq+ ?.V... .,? tl ( )
at reos ea
a4= + Q )
at r ae
At the surface, the wind sutras is specified as
T,. a at W? ?a + 'r.* - P.C.W# W2+ + (9)
where W+ and W. = wind speeds in the + and 8 direc#iotis.
p, w density of air; and C. = drag +sttt at
=tee MV r.
h Tlea kinematic free surface boundary condition is given @3
at a at V at
at r cos 64 ;re
Two options are available to specify the bottom boundary
c oodition
1. Bottom stress c o ndfntion
'rb+ = P-CA,U&V 1' + tr's. -r" - P.Crpr Ui + Wr (I1)
where Cy : bottom drag coefficient; and ui and v., _
velocity componem at the bottom in *e and 0 &ec-
fons. respectively.
2. No-slip condition
a,,=0 and v,=a (12)
At the bottom boundary, no momentum flux is allowed and
the kinematic condition is specified
W= -S4 1 ah - vslah (13)
7 -COS 0 act r ae
The governing equations are transformed to a a-erotdirsate
system to resolve bathymetric variations with a constant num-
ber of grids. The transfitrrnation is defined as
+_*', a=e% r=R+{+(Q-ixt+h)/2. t = e (la)
The governing equations now become (dropping flue primes
E convenience)
nulty
at I auD I avD vD araD
+ - --- - -- tan e + --- = 0 (15)
at r cos 0 a? r ae r arr
Momentum
+-direction
auD + I auuD + 1 auvD - 2uvD tan Ie + auwD - fvD
at r cos 8 a* r ae r aQ
- .S? j [A,+ (p, - 2pXi - Q)) aD .
at, X-1 !A- am
+ (4p - 2p,) + D a* + D av (A" acr (lb)
-direction
SVD + 1 a"D + 1 avuD - au vv D tan 0
rat r cos 9 ac¢ r 80 r
+ a + fuD = - Ex + (p. - 2pX1 - a,))
SW 2pr
+ Op - 2pj iai'i + D aake + 't a (A- av
o--direction
_ -pg {18)
1) aw
Cot swation of &d3$tanan
+-cos @+ r813 +?aQ D2av [D-
2 8
D, +
+ r csr7s?de a8r (19)
where
X= f p do (20a)
e
cu = - (1 + a) at + Y+= + 7.v + w (lob)

1 1 -- Q ah - 1 -F cr

)
-
all
7+ _
D r cat 0 i; 7;0
; 8 4
1
= 1--oah 1+or dt-(20d)
Y?
D 7e-we a8 _
r tcs a a8
where D = h + ,C = total. water depth.
The horizontal velocities and independent variables are next
transformed to a curvilinear coordinate system. The equations
of motion and continuity equation in a curvilinear coordinate
system M 1), in Germs of the contravarian€ velocity compo-
nents, are as follows:
CwMnutty
Jr cos 0 8 + a-, (cos SJVD) + ? (cos IDN"D)
+Jrcos0)=0
(21)
JOURNAL OF HYDRAULIC ENGINEERING /JANUARY 199713
Momentum Equation
t-direction
au'D -00 + D ap
at ^ _ p r ccoss e 2 f1k + (p. 2pXl - o)] al
w
+(4P-2p,)aC+D '\'+0 J+ t+,? ?g
fR 11Js r cosle +(P,-2Px1 - W)l +(4p-2p,)LC+Dak'
CIA J2r 2e k (+4 coieWseu`D + 4, cosWtev`D)
cosai
+ (¢E cos'BtJu`v`D + coewtevw)]
+ Js* $„8 l (8t cos8lx°teD + 8„r coa=BJrt`%eD)
+ a (8E cosWu°v`D + 8„ c os28JtfVD)
{WU°I3} + J nos g f (Sis" +
+ (0.0% + ?'",?V°l + A, Sol (22)
Vdirecdon
ay°iU ; 00,160, + cos W+ t DS M Sly
at J1p r coA 2 + (P. 2RX1 0?l 84
+ (4p - 2p,) at + D X1 a aP e 2
" [L+(p.-2pX1 -e)I
+(4p-2pj +DaX1
Sh an
+ !2r as [5at7 % rOsWMVD + *, cosViev`D)
Cos%
+ ( c o$Wu`teD + ?,? cos'BJrfv`D)
(8E cos u`D + 8, co8heeD)
Jr NIi
+ a (@E c o$%Ju`v`D + % crsB VteD)]
(W V°D) - J COS 8 KBeeE + x`04 d u`
+ {ate, +,,)??" + 4 a (A, awl
D acv . ao? (23)
Conservation of Substance
t + r at + r an + WA._ aD2 a (D. i?-) }. r'J2
IDe,
• + +"0') ta+ dE ) e C065W
ta2q
it
06 82
?
cos
9
where u` and v` = Contravariant velocities in the (k, q) dbw-
tions, respectively, C = water elevation; D = Z + depth; and
4 / JOURNAL OF HYDRAULIC ENaINEER1NGi / JANUARY 1997
the Iacobian, J = ¢,Eti, - +p,BE. The relationship between the
contravsriant velocities (u`, v`) and velocities in spherical co-
ordinates (u. v) is given by
u a COs 4ru, + Cos 60,V, (25a)
V = St", + 814v` (256)
'" t'tIRSCi1.ENCE PARAMETERIZATION
The turbulence paraa3eterization is a key model component
for predicting flow and mixing processes in stratified fluids.
There is, however, no u vetsally accepted procedure to rep-
resent ftubulence (ASCII 1988; Cheng and Smith 1990). In
this study, we employ a one equation turbulent kinetic energy
model to calculate the vertical eddy viscosity and diffusivity.
The length scale is specified using the approach suggested by
Blac:latdar (1962) that has been successfully used in modeling
turbulence for tidal problems (Davies and Jones 1990). The
effect of stratification is accounted for by using an empirical
wJadc ip similar to the ones employed for the mixing length
approach. This model accounts for the convection, diffusion,
and time burry of turbulent kinetic energy in unsteady flows.
'turbulent Energy
The turbulence idnedc energy equation In spherical and a-
coorclinates is given as follows:
ab + to b } v 8b + ab = 4 8A. ab
ar r?98+ rM acr D'aQ a, as
+ A. ag"t) I D ; + D (I av 2A, A?
t'Itr')t + 13g Dar aQ - tt (26)
where tr =ltinetic energy.
After transformation to curvilinear coordinates 71), the
preceding equation can be written as
aab u< a v° ab+ab 4 a A. ab
at + r at + r #q as - D: acr a, as
2 au = 2 aw
+ 0i + (D as I + fig (27)
where 11 = volumetric expansion coefficient; cry = empirical
diffusion constant; at 0 Schundt number; 0 to mean scalar
quantity; and e = ausepation. In this study the interchange
between ttabuletu kinetic energy and poteatisl =ergy or pro-
dtuctiotifeftssipatioa by bwyant forces is ncglectmL It is as-
sumed that the turbulent km w energy is aKdvected and dif-
fused in a homogeneous Add while the effect of stratification
is accounted for by an empirical- formula using a Richardson
number (damping fraction). As argued by Abraham (1988).
the reproduction of internal mixing at tidal dock is beyond the
capability of present tubulence models and, hence, they
should not be used where this aspect is important.
Eddy Viscosity and Diffusivity Relationships
Based on dimensional reasoning the eddy viscosity is re-
lated to the kinetic energy b and mixing length L;. by
A. = C„ LM-Vb (28)
where C. = empirical constant.
In homogeneous water, the vertical eddy viscosity and dif-
fusivity are considered to be equal, A. = D,. In the presence
of a stable vertical density gradient, both A. and D, arse lower
than their homogeneous values. The magnitude of A. is always
greater than the corresponding value of D,.
The general form for the eddy viscosity and diffusivity arc
given as
A. = f (RJC„ L,.Vb- (29a)
D„ - g(R,)C„ L.Vb (29b)
• yr asemumpi rival relations for f(N and g(N have been
by Munk and Anderson (1945) and Officer (1976).
Munk and Anderson (1948)
f(R,) = (1 + 10.0Rd' (30a)
g(Ra _ (1 + 3.33N" (30b)
offloer (1976)
f(Ra _ (1 + R,}"' (31a)
g(R,) = (I + R r (31b)
where the Richardson tratubm Rt. is defined by
131ss1patioh
aP
Zg ?
Lam 1+
From dimeetmsional analysis die expression for dUs ion, in
tams of the turbulent kmm.c ==V and mixing leogtb, a
given by
e = C,{VIII,.) (33)
;Z9 Q = !ircal constannr
LAMQth
The mixing length formulation proposed by B1ackadar
(1962) is
_ KMI + («r - 1
+ =I + {Q - 1)f2j
k
where ,K a 'ion Kat3ttneWs Wit; D = total water depth and
in which die, inh ng length. L., increases from the tar bottom
to the surface and the valor ofLw is dMazineed by the vertical,
distribution of die turbulent energy as fiAbm:
(r b'ajl + (ter - 1)rA der
L. - yD J a f (35)
b'4 dos
x
The constant y determines the vertical extent of the bound-
ary layer and vertical eddy viscosity, and is adjusted to match
field observations. The viscosity Watases rapidly with in-
creasing y in both amplitude and vertical extent (Mofjeld and
Lavelle 1983). The constant y typically ranges from 0.05 to
0.3. The coefficients in (28). (34), and. (35) have values C. =
0.463; C, = 0.1; art, = 137; and K = 0.4 (Davies and Jones
1990).
EMoundary Conditlons
The boundary condition at the surface is specified as
D 'Z

Where: U*, = friction velocity due to the wind stress and at,
a„ are coefficients. A similar boundary condition is used by
Davies and Jones (1988) in which art = 0.73, aid a„ = 2.6. In
the absence of wind forcing the flux of turbulence at the sur-
face
Forr a?slig bottom boundary condition, the turbulent ki-
netic energy flux into the sea bed is zero (Davies and Jones
1988) and, therefore
ab = 0 (37)
acr
For the bottom stress boundary condition, the bottom
boundary layer is not resolved in detail,. The turbulent kinetic
energy, b, at the first grid point near the wall (where the tur-
bale nce is assumed in equilibrium and the velocity follows the
log: law) is given as follows:
b = U*, C„ C. (38)
where U*. - hudont vdocky associated with the bottom stress.
While this boundary condition is not always rigorously satis-
fied unsteady condiidons (Cclik end Roth 1985), it is
used as a fast-order a ppt?timatitsa.
SOUMON TECMQUE
The basic approach is to transtbrta the dependent, as well
as independent, vadiables in sphadcal coordi> s co a curvi-
linear coordinate system. Ile equation of motion is split into
exterm and Interior modes to increase the allowable time step
and, hermm reduce d w coal uw-
Mw velocity is decoy into
re° = tr + se, (39a)
VF = V + If, (39b)
where (UO, V'`) and (e, V) = vertically averaged velocities
and deviation velocity (from the vertically avaned velocity)
in %, q) direeetions, ri?vedy. Solution of dw exterior mode
using a se"miimplicaitt (space staggered grid) solution. method-
ptagy, and pmsetrtationsof the appromch used to generate the
boundary conforming grid are presented by Muin and Spauld-
ing (1996). The focus here is on three-dim ensionat (3D) as-
pects, including the deviation velocity and the turbulence
equation.
Subtracting the vertically averaged momentum equations
from dies 3D momesitum ins gives the vertical. deviation
velocity equations of motion
-(A- see` D 4 a arc"
at _ D w ? -F A (40cr)
W
acs ?A" aerr +D (40b)
atD = 3
where A and B = nonbarotrapic terms in the equations of mo-
tion. These terms are solved explicitly: The diffusion term in
(40) is solved implicitly using a three-level scheme to damp
out spurious oscillations (Fletcher 1988). The algorithm is sec-
ond-order accurate both in time and spe ce. A tridiagoaal set
of equations in the unknown velocity deviation is solved using
a Thomas algorithm. Both the exterior and interior modes are
solved at the same time step.
The finite difference procedure used to solve the turbulent
kinetic energy equations has been described by Davies and
Jones (1990). In the present steady, a date-level time discret-
irAflon (Fletcher 198g) is used instead of the Crank-Nicholson
method of Davies sad Jones (1990). A nonstaggcnd grid is
used in the vertical. The C farm of Davies and Jones' (1990)
numerical scheme is employed to calculate the dissipation term
JOURNAL OF HYDRAULIC ENGINEERING /JANUARY 1997 / 5
in the energy equation to ease the time stem restrictiom No
iteration or filtering is employed The; tithe stop is restricted
by the horizontal advection term. As will be shown in model
testing, a CFL equal to 100 can be used to predict the vesrtical
structure of tidally induced flows.
The transport model (24) is solved by a simple explicit taeh-
nique, except for the vertical dlffns on that is solved by an
implicit scheme to ease the time step restriction due to the
small vertical length scales. In the pa+esehit model, two options
am available to solve the advection farm. The first optic is a
Lax Wendroff scheme. which its consistent with a second-order
truncation error (Fletcbesr 1988). The second option is an up.
wind-differencing scheme (fimt-ostler agate) that introduces
artificial diffusivity. The horizontal diffusion term is solved by
a centexred-in-space, explicit technique. The diffusive and ad-
vecxive stability criteria, in these numerical techniques arc At
< &24240. and At < As/Et,, where As and U, = horizontal
grid size and velocity, respectivrly. To avoid spatial oscilla-
tions, the Last-We ll scheme requires A > U,t PM This
gives approximately the sauce amount of atrfi iiciat viscounty as
Inherent in the upwind scheme.
MODEL TEL
Model formulation and ihzzplemeettmion, in co t4mw code
wM+a compared to analytical solutions in which rim air
convective acceleration and Coriolis terms were removed and
the governing equations solved on a q*e.rical coordinate .
testa, which because of the Limited domain approxituate ct a Car.
tubm grind. Additional test simulations were perfornned to con-
fine the operation, of the turbulent closure equations to predict
ft vertical strUCture of tidal flow and compared to a previous
n i study by Davies and Jones (1990). The, model was
tested in an application to salinity intrusion in a simple sec-
channel representative of the Rotterdam Waterway;
dual Fleur
'Then ability of the model to predict residual flow was tamed
for a basin with vertically constant density and viscosity. The
sudaere boundary was forced by a constant wired sums if wind
forcing was used. The teat was perfonued in a simple, rectut-
gutm and constant depth channel open at one end (west). This
model was run for two bottom boundary conditions: (1) no-
slip condition; and (2) bottom stress conditie m
Following Officer's (1976) approach and neglecting advec-
don, tine horizontal diffusion of momentum, and the cmaa
channel term (equadoaun laterally avratage4 the steady-ante
eatpreasion for the vertical velocity pr e.t with linearized bot-
tom Motion can be given as follows
A + h2 + h'l (ki s?hi' ?fz?2
+!' I+h+ z
p (k A. A)
where
(41)
[-gA QW + 8P h` + h + h' P k 10 °
sc (42j
h: hr
k k + i;Q
here A = horizontal density gradient; g = gravity; e = water
elevation slope, -r, = wind stress; u. = river flow per width;
and k = linearized bottom fricttion. A similar equation for it
no-slip condition at the bottom is given on page 12o of offrear,
(1976).
Three separate simulations with different forcings we,
studied: (1) density gradient flow; (2) wind driven flow; ar
(3) density gradient, wind, and river-induced flow. In they
simulations. the following conditions were assumed: the der
sity increases linearly from the head (closed end) to the mout
(open end) A = -0.00036 kg/m'; wind stress z, = 0.01 N/n
(L dynect0; river flow w = -o.i mss; depth h = 10 n
vertical viscosity A. = 10 cm2/s; and linearized bottom frictio
k = 0.05 cm/s. Depending on the case the appropriate forcin
parameters were used. Testing was performed rasing five. 1t
and 20 vertical levels. The model was started with zero ve
iocities and elevation. The density gradient was applied grad
wally until a steady state was achieved
Deatrity Gradiew Faming
Fig. I(a) shows a comparison of the model prediction tc
analytic solution for the bottom stress fimmulation under den-
sity gradient forcing. Model predictions approach the analytic
solution as the gadd resolution is increased. The model over-
predicts the currents the bottom and surface at low grid
resolution, The maximum errors are about 7% for five levels.
2% for 10 le=vels, and less than 1% for 20 Levels. The model
was also rein with a n 4lip bottom boundary condition, as
shown in rig. 1(b). When the surface boundary condition was
specified using a second-or le r stogy representation, the
model tower reached steady state even with 80 Levels. This
problem may be cats ed by an utnderestimme of the bottom
friction. which Is only first-order accurate. The model, how-
ever, reached steady state when the sur€ Ae boundary was re-
docesd to Am orft. For this approximation the model over-
predicted die velocity near the smfac a by 20% [Fig. l(b)]
indgmtdR a of this number of the vertical levels.
Wend Forcing
C ompar son of model predictions with the analytic solution
under constant wind forcing with a bottom stress condition is
W

eba
Fitt. 1. Comparison of Model Predicted V"cal Structure of
Wk:eity with Analytic Solution for Density4ndueed Forcing (A.
a 10 ems/s, A r -0.00036 kgW, k• 0.05 eaanls) for. (a) Sodom
Stress; and (b) No-Slip Bottom Boundary Condition (Model Re-
suite Are Presented for 5, 10, and 20 vertical Levels)
6 / JOURNAL OF HYDRAULIC ENGINEERING /JANUARY 1997
41, s? .nos o cos not "
Yd*CW (n>f
-0.1 -am 0 OAS W
V"00'eem
1.1

82 41 0 U 0.2 OJ
v
43 O06 • &W 0 US cis 6Z
V6090Y 604
FXL 2. Comparison of Model Predicted Vwgc d Stucture of
vitetcl#y With Sdutlon for Wind Driven NOW (A, a 10
ae* I Analytic ? k. OAS aWS) tor: (a) Bottom
80"*; and (b) H"llp Bottom Boundary Condition Oft" Ro-
stria Are Pro ed for G, 10, and 20 Yw&M Lw4Ws)
shown in Fig. 2(a). It cad be seen that as the resolution in.
creases the mold prodiebons approa& the analytic solution„
aspecialty near the bottom. The model ?? the vertical
velocity structure more accurately thm for tine dewy induced
=11ow problem The maximum errors are about 291'x` for five lev
GIs, 0.6% for 10 levels, and 0.2% for 20 levels. A similar
problem. as in the deasity4n uc ed flow, was found for the no-
slip condition at the bottom said the boundary condition at the
surface was modified to fira orlon The results arc shown in
Fig, 2(b). Again model won for this ease is mom accu-
rate than in the baroclinic forcing problem.
Demay Gradient Woad a River Forcing
The last test curse considered flow driven by a combination
of density gt ent„ wind, and river flow. The model was tun
using 20 levels. The results, not shown here, were simulated
for bottom stress and nonslip bottom specifications, respw-
tively. The agreement is event (4w%) for the bottom
sftss bottom boundary condidion. The model undetprediors
the verity by about 5% in the mid- epth region for the no-
slip bottom boundary condition.
,ncw t)rdvetn Flow
Ttvo tests were employed to check the model's ability to
simulate the vertical structure of tidal flow. The first test case
is a point model in which the bottom boundary is specifies)
using a no-slip condition. and the water slope is assumed
known. The model was tested against constant and linearly
varying vertical eddy viscosities. In the second test a bottom
stress condition was employed at the sea bed. The bottom fire-
Lion was linearized and related to the vertically averaged ve-
locity.
ENEWoGtt Model Test
Conn4nt Viscosity
The analytic solution for this problem was given in article
347 in Lamb (1945). The following data are used in model
.U
Al N A I I

A V W I

05 ?3 _o.a &1 03 0.1
vd**("N
M.?rk . 3M p ei7n
o TA x ten • 7Tn
0 2Tn 3TA + T
RM 3. C4wnparlson of Modal: Pradkftd Moloch Structure
with Analytic Soludo n for '!Wally Dttnn Flow Omposad Pres-
sure Gradient of OMS HMM with Conalaat VertieslViseoslty, A.
n0.011 msisatilaTkmkdwva[sTtwouo0n* tCyclo{T me
Sttp, tit= x.45 s)
testing. The imposed pine gradient was 0.058 N(m'; period
T = 12.42 h; depth k = 20 m; vertical viscosity A, = 0.011
ni%-, and timer step At = 279.45 s (160 stems per cycle). The
test was performed using 20 Lovell. 3Lc model was started
with zero vel©citm The water slope was applied gradually
(linear ramp over 4 cycles) until a steady staitie was achieved.
meson between the analytic solution and the model pre-
diction is shown in Fig. 3. The agreement is excellent through-
out the water column.
%scosuy Varying b neariy with Height
Iwo simulations were studied with viscosity; one increasing
and one decreasing linearly from the sea bed to the sea surface.
The analytic solution is presented in Prandle (1982). Simula-
tions were performed using the same de)th. grid sire, period,
time step, sea surface slope, and initial condition as the con-
stant viscosity test case.
In the case of viscosity increasing linearly from the bottom
(sea surface), the viscosity at dm sea bed (surface) is set at
A, = 0.001 n?/s; and the viscosity at the sea surface (bed) A.
= 0.021 m%. The awft of time simulat ores am in excellent
agreement with the analytic solutions. The bonndmy layer in
the linearly increasing case is (vef f vii the sea bed)
thinner than the constant viscosity ease due to lltee lower vis-
cosity new the bottom. The boundary layer. for the linearly
decreasing case its thicker than for rite constant viscosity case
and occupies the whole water column due to the fact that the
vertical viscosity at the bottom is higher than in the two pre-
vio us cases.
3D Testing
Lynch and Officer (1985) derived an analytic solution for
the 3D Sow driven by periodic forcing, with linearized bottom
stress (kub, kva) and linked to the vertically averaged solution
for an annular channel. The solutions were assembled from
one-dimensional (11)) vertical diffusion and 2D vertically av-
eraged solutions of the governing equations.
Consider the quarter-circle geometry with quadratically var-
ying bathymetry Jr = h,r2. Note r refers to the radius of the
annual channel. The sketch of geometry, bathymetry, and grid
configuration are shown in Fig. 4. The viscosity is constant
throughout the depth. The analytic solution, however; requires
that Ad(f2h) and MIA, be constant, and hence A. and k must
JOURNAL OF HYDRAULIC ENGINEERING / JANUARY 1997 / 7
F
(i)
(b)
(C)
FIG. 4. TIVee-Diawnslonal Geometry;(b)Saft tr+l, and (Tidally Model Test for. ntlion 14 *11 5O
m;rea31,26A an b-6(r/rin
4
.4
's
4
40
-t2
.K
-0.3 -03 41 0.1 0.3 03
7 Yeioc3gr (q?)
• star a a
oa r2= X 4W a 7W
a un T
PIG. 0. Vertical Structure of Vafocky at him mt orita of i/S of Uz
Tidal Pefod at r:16,880 m and * = 39.4.16r Three-13knendotnal
Model Test In Annular Section t twnn el, r, w S,98ti m; r: a SIA50
m; A,1(01V? = 0.1; khJA, a 10; At= 858.9 a
vary horizontally. Model tests were performed using a coptirse,
slightly nonorthogonal 7 x 7 grid system. The following pa-
rameters were used: inner radius r, = 9,950 m; outer radius r,
= 31,250 m; f2 = 1.4 x 10''s-`; klt/A,. = 10; A.I(nh? =0.1,
and h. = 5/r; m-'. The open boundary was sped8ed by var-
ying the tidal amplitude 0.1 cos(2*) m, where = rotation
angle. The model was run using eight and 20 levels is the
vertical and time steps of 279.45, 558.9. and 1117.8 s.
Comparison of the model and analytical solution at point
(5, 5) or at radius 16.60 m and * = 39.375° for 20 ksvels
with a time step of 558.9 s at one-eighth period increment is
shown in Fig. 5. The agreement is very good. The largest
errors (<10%) are near the surface area.
Sensitivity of the model predicted new surface currents (at
T/8, 774, 3T18, T/2) to grid resolution and time step in the near
surface region is shown in Table 1. The maximum errors occur
at slack tide (at TY2). The model predicted errors decrease with
decreasing time step. Model errors using eight vertical levels
are approximately the same as those using 20 vertical levels.
A veer plot of the velocity field at the surface at 774 (not
presented) shows that the agreement between model predic.
dons and analytic solution is excellent, even though the grid
was relatively coarse and slightly nonorthogonal. The errors
arc less than 5%, except at the odrm point of the inner radius
r = rt. Here they are about 10% due to the fact that the velocity
is very small at this location. The errors become much smaller
(•c0.6%) at the outer radius new the open boundary. Compar-
ison of the model-predicted velocity time series at a radius of
16,660 m. * w 39.375, acrd for 0.35 m and 13.65 m below
the sea surface with the analytic soludoa arc shown in Fig. &
The bottom velocity leads the surface velocity by 0.85 h. Pre-
dictions at again in excellent agreement with the analytic so-
lution.
Turbulemm Mtn 81muhrtlms
.A simulation was paftwed in an open-closed. rectangular
channel drivers with tidal forhiag„ and a water depth of 10 m.
The tel. length is 51.34 km, and is represented by 20
horizowd Sdds. IU tidal amplitude was 1.2 m, with a period
of 1242 h, 7 = OA. A point 5,55 km ft m the open channel,
whore time pressure, .sradient has a antguitude that would give
a cut with atraptitade to mis in an inviscid calculation,
was chosen to study the vertical structure of the velocity, eddy
"scos ty, and turbulent entergy. The simulation assumed a ho-
TABLE 1. Nkxh 1 P ors Errors (%) of Surface Velocity at r
a 16A6fiti m and V . 8ti.4' for Annular Section Channel with
tluadtattc Saff nwtry Wing 8 and 20 V+ UCSI Lawn with This
Steps of 279.45, 538.9, and 1117.8 a
8 Levi 1 20 Laura!
279.45 s 558:9 a 11174 s 279AS s 558.0 a 1117.8 ?
(CFL = (CFL w (CFI- w (CFL w (CFL w (CFL w
t o s) 1.0) 2.0) 3.1) 8.2) 12.4)
(t) (2) (3) (4) (5) (6) (7l
178 4.1 4.2 4.8 3.9 44 4.6
714 3.7 3.7 4.0 3 3 33 3.9
3278 3r 3A 30 3t 3.9 3.0
7X2 tt.7 10.0 12A 7.6 Ls 11.6
VdK tfa#pPop ragSwlot
-1dA40N Ma0W. As47lAk2K-d
9A
a.?
0
r..ai
4A
_ _ 7%0&0 a
FIG. 6. Comparison of Model Predicted Velocity Tlaw Series
with Analytical Solution at ra 16,880 m and * = 39.4' for Three-
01manelonai Model Tait in Annular Section Channel Driven by
Aft Tide at Open Boundary with Varying Amplitude of ;. = 0.1
cos(2*) m; r, s 9,950 tit; rt a 31,25Q m; AACW5 a 0.1; Ah7A,=10,
At a 279.45 a; and 20 Vertical Levels
8 / JOURNAL OF HYDRAULIC ENGINEERING / JANUARY 1997
W
e
a7

4 44 42 apt ter r
vaodgGNo
FKL 7. C+srrgWrloon of (0) Model Pr*dkftd Vettlaal i5;lhslcb"
of Veloetty with (t?) 'Num rival Simulations of 0"" and Jot
09100) for lence Model Test T with lImposed r+a G?rehdWd of 0.14 NW; tea
Win Boundary tatttdttoen T a 4A; Atw 6S$.9 s; and 401fW*W
%viela
w

o am a,m .;ar

4-f
0 "1 Oar 0M
Vr?oe+iKtmih)
Vise"" with {b) Numerical r Simulations, Vairtics! SUV*Wm
Of Vise"" With (b) Numerical Simulations, of Davies and Janes
(1 9W) for One-Dimensional Tudwierm Model Test Driven by Ad,
TICIS with imposed Pressure Gn cent of M14 Nh",; N"Ilp Sor-
ndary Condi#on; -t = 0.4; At a 55" s; and 40 Vertical
NEEksle
mO Aeous fluid. The Coriolis, baroclinic, and advective terms
were neglected to compare the present results with the circu-
lation and turbulence model developed by Davies and Jones
(1990).
hmnndarv simulations
were conducted using 40 levels with a time step of 558.9 s.
A comparison between the results of the present model (40
levels) and Davies and Jones' (1994) with 100 levels and a
logarithmic transformation is shown in Pigs. 7-10. Results are
given atone-eighth intervals during the tidal cycle. The max-
imum surface velocity of the present model is about 20%

r "apt aaa aaac *= am
Tabdoweemnalm
9. t: muperfew of (a) Modd Puled Ver*sl Structure
of Turin lenm Eat wit, (b) Nuawdeal Simulations of DavNs
and Jones (1o" far Ons4?kmm*lo W Turb Werm Model Test
D &A" by A16 Tk*v4 h imposed Pressure Gradlent of 0.14 N/m°;
Ka-Slip actlom Boundary Condloon;-1 a Q.4; At= 558.9 a; and
40 Vertical Levels
tt

S 4 a r 2 7
serascK?7
(b)

a s a e i s i
saw C'?3
FIG. 10. Comparison of (a) Model Predicted Vertical Structure
of Shear Stress with (b) Numerteel Simulations of Davies and
Jones (1990) for One-Dirttansional Turbulence Modal Teat
Driven by A4 Tkie with Imposed Pressure Gradient of 0.14 N/m';
N"Ilp Bottom Boundary Condttlon; 7 : 0.4; At • 658.9 s; and
40 Vertical t.svels
Vs tW*
a nom am awn #M am
UbalwMawcom
lower than their results. The structure of the eddy viscosity,
4mient energy, and shear stress are similar However. the
,om shear stresses arc twice as high in Davies and Jones
tiM) than in the present simulation because the present gt'hl
structure does not provide sufficient resolution in the near--bed
'oa. 't'his problem is mote severe at low grid resolution.
For die bottom stress specification, saxnuiatiomc were per
using 10 and 40 levels with a time step of 279.45 s.
In these simulations the bottom drag coefficiers wax $et at
0.0025. and Y = OA. A comparison between dinubdons using
high (40 levels) and low vertical resolution (10 kmo is shown
in Fig. 11 for the vakw ty profile, 'liU mmftm viscosity,
shear stress, and energy (not shown) computed using the low
resolution grid are apptrc 1mately 259Y higher than simulations
using the high ws"on grid. The velocity strucOm 4110- 1 M
hovrnen4 is not significa ay acted. Further tests s ell that
s stabtc and accurate velocity prediction can be oktailned using
di 4 X S ! M t rs
at
8
RQ 11, Cottlparfton of #ifoditt`Pr dkated Vft1W StruesU" of
Using (a) Open l td hbacAlo"T&dDt!VO ,bV
Tithe 0adoM t:lt 0W Candi t%--t s+tl.4; 4a; 0A42 ft A t a ? s
• ? •? sow ti?q
0 e
•
•
m
r
•
•
E ?t0 •
a -FR
0.5 1 1.s
velocity (MIS)
AQ 12. Compe rism of Modal (Bottom Stress; CaedItIon)Pte-
dicted Vertleal Structure of Velocity with Nunvuftsl SimuutatIms
of Davies and Jones (1988) Driven by Wield Stress; s,:1.0 Nhn=;
a : 0.0025: and y : 0.2
a time step of 1117.8 s (550 CFI., based on the diffusive time
shale for 40 levels).
The model was also tested against steady wind-induced flow
with a depth of 100 m„ a wind stress of i Min', a bottom
stress specification; 20 levels, with a friction coefficient of, c
= 0,0025, and 7 - 0.2- A comparison of the velocity computed
using the present model and similar results by Davies and
Janes (1988) with 100 levels and a logarithmic transformation
is presented in Fig, 12. 't'he agreement is very good. A max.
imura difference of 5% is predicted near the surface and the
sm bead. Tice model-Pro dicta vertical structure of viscosity
gives excellent: agreement at middepth and air the surface,
but Slightly overprteclicts at the bottom- The turbulent energy
simulated by the present model is higher than Davies and
,Jones' (15) modal both at the surface and bottom. Differ-
ences that occur am the bottom are due to differences in the
bottoin boundary condition specification. The present simula.
tions employ it bottom stems condition what the turbulent
energy at to sea bed is specified while Davies and Jones
(1988) we a no-slip bottom condition and specify no energy
flux at the sea bed. In gcnl the agreement is exce&nt al.
though do VesW wo& uses relatively lost grid resolution
compared fa Davies and lam (1988).
Salinity k*uslar i Simulaido is
Ippen and i arl an (1961) derived an analytical solution
for salinity intrusion under the assumption that the salinity
distribution can be represented. by the equilibrium of the 1D
convmtive-diffusion processes where the time and crass-sec-
donaily, averaged fresh wader (seaward) flux of sack is balanced
by the horizontal diffusive hurt of salt (landward). The effect
of grav to iortal convection by density differeacxs (density in-
duded) is negld. Consider a rectangular channel with a
lavi t of 105.5 kiu> a river flow velocity of O()00714 mis, and
Mental diffusion coefficicats of 4, 6. 8, and 10 uNs. The
a3tdve ctive term, in the salt transport equation is solved by the
Dane Watdtoff method. 'Tire open boundary is specified by a
constant salinity of 30 ppt< Comparison between model pre-
dictions and the analytic solution for various values of the
borbontal Mksiron coefficient D1, is shown in Fig. 13. The
atgre miliza m, -it between the model and atnalytical solution is ex-
"Hettt.
Finally die irk was used to predict the salinity intrusion
in Rsatterdem. Waterway using deantic d conditions to those em-
ployed by Smith sad Takhar (1981). The simulation was in-
tended to evaluates the ability of the model to predict salinity
intrusion. Tic waterway was represented by a rectangular
channel with a length of 99 km. Mw width and depth were
30
25
• q. eon=s
20 a Qi't,.xA
is A D?.tw?A
y 10 ?*rrds
20 40 60 to loo
DIM= Gem 0" cM}
FIG. 13. Comparison of Model Predicted Sastrtty Distribution
with Anatytic Solution for ane•OlmsosionW Salft ty Intrusion
?first (Thm"rt Equation Is Solved by LaxaNendroff Method;
River Flow Velocity to 0.000714 m/s; and Horb= tal Diffusion
Coefficients of 4, 8, 8, and 10 W/o Are used)
s r y e sr r u
SOWN
kept constant with values of 400 and 13 m. respectively. The
river inflow was 1.000 &/s. 'The model was run using 40 grids
along the channel and 20 levels in the vertical. The initial
coalitions for velocity, elevation, and salinity were set to zero.
Along the open boundary (mouth) the salinity distribution is
to vary from 30 pppt at the bottom to 20 ppt at the
assumed surface on infiow. The model was tun with an U2 tide. The
tine step was 558.9 s with a tidal amplitude at the open
boundary of 0.9 m The adveective term in the salt transport
equation was solved using the upwind method. The Las:-Wen-
droll method was not used because it required a large hod-
zolad diffusivity (-5000 msls) to mai t ilaia stability. T
model was rim for 66 d to achieve steady states.
A simulation was performed in wbich the vertical viscosity
and diffusivity were calculated by the turbulence model. The
bottonn friction, Q, was 0.0014 It was found that the model
was very sensitive to the value of 7 in do mulling length spex-
dicaum Since the turbulent energy source a fiout the bottom
Wundsty, the bottom crag comet: Cr, is also important in
dommuning the vertical velocity structure,. Fig. 14 shows the
salinity diet ibution along the channel for a - 0.0 and Y
:0.0 with the empirical fevInu -mm of (30), which was taicccn
f Officer (1976). implemented to represent err cation
effects. Smith and'IEalci wen (1981) mtodcl predicdtaas and field.
observations are also drown Uft 14(m)]. The ruts show that
the model-predicted high tide salinity distribution is in reason-
able agreemeiti with and an improvement over Smith and Tale-
33
30,4
tt
I$
tut
s
a
0
I

(b)
l,5 20 1S 30 3S
t bW" rMn mWh pnal
0090, 14, Comparison of Me" Predicted Satkft Oisbibutton
- ad- Channel with C. bewvetttons and Nuetterrkal Stmulatton of
ittt and Takher (1981) for Rotterdam Watsrway at; (a) High
Tlds.- and (b) Low Tide (Vertical VWcosity anti Dilluetvtty Are Ob-
tsknsd ft m Turbulence Model Using Bottom Friction; C„
0- o ; and y a 04)
10 13 20 25 30 35
o?mcus ? atuwdt t?3
saw* okwkrkn at tatty Tue.
eb«0.ct?as. lr0e.oa
33
30, t Ob"r,SW(wo
+w ota?.wBa
g

` -140114 soma
e ....5mrtttwkTsklw swraa
• • SwA"Ttkkw. Boma
?

is `?
- C i
,?
E ?' g--
-
it)

a

S
`. ¦ `. •
4 -
.
!
_
e
0
har's results. Both the present and Smith and Takhar (1981)
models do not accurately predict the low tide salinity distri-
bution. As analyzed by Smith and Takhar (1981), the poor
model perfa mince for the low water salinity distribution is
caused by the dock system in the waterway acting as a source
and sink of salt on the ebb and flood tide, respectively.
CQNCLUSM
A detailed description of the 3D boundary-fitted circulation
model is spherical coordinates for coastal waters is presented.
Both the dependent and independent horizontal variables are
transfmmcd to a boundary-fitted coordinate systcttr. Tres equa-
tions are also transformed to a-coordinates to resolve the var-
iation in bathymetrry. Both the exterior and interior mode are
solved using the same time step. The numerical scheme is
second order in time and apace- The time step is not restricted
by the shallow water gravity wave and varied diffusion CFL
criteria. The eddy viscosity/dilf'usivity can be specified or ob-
tained from a one equation turbulence energy model.
A series of model tests to Raw problems shows that the
present model. Is fully capable of predicting the vertical sttuc-
true of the How in response to tidal, wind, riven and density
forcing. The 3D =o*4 test in an annular sectim Channel with
quadratic bathtymatty under tidal fig box shown the
model's ability to resolve a more complicated geometry and
bathymctry.
The model, with a bottom stress condition, gives good pre
diction of the vartical structure of the velocity; shear stress,
ice enaV, and eddy viscosity even at modest vertical
grid resolutiotis. No iteration or Blteft is en4Aqyed. no-
stir bottom boundary condition. version of thepresent model
fails to accurately predict the slur stress and eaeW distri-
butions at the sea bed for 40 vertical levels because of the lack
of vertical resolution. new the sea beef.
Agreement. bit the model and analytic solution is c;x-
cellent for the ID salinity intrusion problem where the density
gradient induced flow is neglected. The model omurately pre-
dictrarl, the salinity distribution At high tide in the Rotterdam
Waterway where the viscosity/dif usivity were obtained from
a turbulence. mrideL Ties poor results at low tide were probably
caused by the lack of coon of the effect of the dock
system on the salinity field (Smith and 3akhar 1981).
The CPU time of the iuterild mode with trrtWence model
for each water cell per computational step is 3.1 X 10"5 min
on a 48G150 Mfr personal wmputer systen using a L,ahey
F7732 Vey 5.1 Fortruttoompilm The. CPU time of the
exterud mode is 2.9 X 10"'; min using the Satrle machine and
comtpil=
APPENINX L REFERENCES
Abraham, 0: (19tf10„ ' Tturtmdatcels and miring in stratified tidal Bows,
Physiedl processes. in estaa rks. P. Dronkers and R. Lmssen, eds„
Springer-Vaft XG. Berlin. Gennasy.
ASC E Thsk Conuniare+e on 7hrhakrrce Models in H;ydiasdiC Compumdom
(1988). '*Turbulence modeling of surface water flow and transport: Pact
1." J Hydr. Engrg.. ASCF. 114(9). 970-991.
Blackedar, A. K (1962). '-the vertical distribution of wind and turbulent
exchange in a sentral atmosphere." J. Geophys. Am. 67.3095-3120.
C elik, L, and Rod, W. (1985). " Alculation of wawa-hulaced turbulent
Bows in estuaties." Oc. Engrg., 12(6).531-542,
Cheng. R. T.. and Smith, P. E (19900. "A survey of dtree-dimensional
numerical, estuarim models." 1*sruaccuinne and cdand anodeting, M. 1..
Spaulding, ed, ASM New York. N.Y.. 1-15.
Davies. A. M« and Jones. J, iw (1998). "Modelling ttubdence in shallow
sea regions." Satan-srdle to 6ulm a and mtxfng is dw ocean. Pmc.,
19 Liege C:ottogtdrun on Or- h5mdrodyn.. J. C. Mdxmd and B. M. Jannart,
eds.. Unix of Liege. Liege. Belgium.
Davies, A. M.. and Jones. J. L (1990). "on the muncrita) solution of
the turbuteaee energy equations for wave and tidal !laws." Ice. J. for
Numer. Meth. in fluids. 11. 1-25.
JOURNAL OF HYDRAULIC ENGINEERING /JANUARY 1997 / 11
s tl tadwt at *fth Two
et,a00s, v. *'"
FletchM C. A. J. (1988). Computadonal techniques for A" dynanuc4
volume t, fwWonehtW and generat mchaeiques. Springa6Verlag New
York, Inc., New York. N.Y.
Ippen. A. T., and Holleman, D. IL F. (1961). "One-dimcusionsi analysis
of salinity intrusion is estuaries.- 7kch. BIA No. S. Cam. ore Tidal
Hyde., U.S. Army Corps of Engrs.. Fort Belvoir. Va.
Johnsae. B. H. (1980. ••VAMA-A vertieally averaged ltdrcrdytramie
model using boundary-fitted =00SWcea." MP HL-80-3, U.S. Amy
Corp of Engm Wtrwy. Experiment Station. Vicksbaug. lwOW
Lamb. H. (1945). Mydrodp wiles. Denver Publ caaticins, 1ue.« New York,
N.Y.
Lynch. D. R.. and Gray. W. G. (1978). "Analytic sohttionts fat CMPUW
How model te=sting.- J. JYy&.. Diyx AS4 , 104(001,1409-1428-
Lynch, D. R., and 001M G B. (IM). "Analytic wWdm for three-
dimartsianai hydrodynamic model testiW* tnL A for Nrar Meth.
Raids, S. 529-543.
Lynch, D. R„ and Wexner, E E. (1913'?). ` IlydrOdy-
I on linlw-ek? Part L Linearized harmonic modal." tat, A
forXwne: Me& in aFIvAir, 7.871-W9.
Mofj*K H. O« and Lavelle, J. W. (1984). `fig tlta length scale in a
second-order ciaaurc model of the unwed botmn baundwy !ayes:"
J. Phys. Ociminagrea;phy, 14, 833-839.
Main. iv1. (1993). `•A tbr? dimensional boumdty-fitted cir iaa MOM
in spherical coocdinstes," FAD dissertation. Univ. of Made Island.
Narragansett Bay' Campus. Narragansett. R-L
Muin. M.. and Spaulcfta& M. L,. (1496). ' birundary-
in sphoical .. J Hj* ftrt,,
ASdF, 122(9).512-521.
Mimic, W. H., and Anderson, L R. (2948). "Nolen on 6=7 Of theer-
tnnodhw" ! Marine Res... 7.2'76.
Ober. C. B. (1974 Pk Wotad ocewwgi why of MAwfes. Jou=r Wileay tit
Sons, Inc.. New Yoick. N.Y.. 120.
Ptandle, D. (1982). "Tiro vortical structure Of *W woe s." o +eapdays.
AwmphDm Fhdd D*" 2Z. 29-49.
Sben& Y. P. (1986). "A tb rtadisstemsiorral matherna" mold of coastal.
eastisaine and 14m currents =sing boundary-fitted grid." Took Rgpg 16?
SM Aeronautical Research} Associates of Pklir4o0on, Prh"X4 NJ-
Smith T. J.. and TAdW N. & (1981). "A madman" model rot' pars`
daft tttlxed a m is using the turbulence energy egaadoga" Em -
rhm Coast. and She &f' 13, 27-43.
Spaulding, M. L. (1984), "A va ncally averaged eke"=model axing
bowxWy-fitted coordinates." 1 Phys Oc"nag;rW ft,14, 973-982.
Swanson. 1. C. (1986). "`A metnsional =mwkd motfd system of
coastal circulation and wtow quality." Phi? dissertation. Univ of
Rhode Island. Kiingstost, R,L
APPENOW 11. NarATION
77u fvttowmg symbols are used in dds paper:
A. = vertical eddy viscosity;
a = tidal wave ampl=itude;
b - turbulence idn edc enerar,
C. - empirical pmt in eddy viscosity redadaud*,
C. - drag coefficient at stati=on
Ci - dmg codf dent at btu
Q as empirical coustaut in evert dissipation relalai shin
D = elevation + water depth;
D,, = horizontal eddy diffusivity;
D. = vertical eddy d4f wiv ty;
g = gravitation;
h = water de=pth;
J = Jacobi=n of curvilinear= coordinate;
K = Von Karrnan canstaeng .
k = linearized bottom friction;
L = wave length;
L,. = mining length;
I = length of channel;
n = nod number
P pressure,
q = concentration of subsunce;
R = radius of earth;
Re = Richardsort number.
T = wave period.;
I = tip
W. = liver flow;
U*, = fric dm velocity flue to wind stress;
U,,, = friction velocity due to botto=m stress;
U. V = venally averaged velocity is + and 6 direction;
U`. Y° = vertically averaged qty in curvilinear coordinate;
U. A w= aster velocity in 44 9. r direction;
rf as wow velocity in ±ctlrvilinam coordinatt;
4 = bottom velocity 4 won
w = bomm velocity is 8 tins=;
W* - wind speed in 4s won;
Wo = wind speckt in 9 direction;
A = volurnetric expansion coefficient;
y - constant pct in mixing length formulation.
re. = dissipation raw of ,
- water'QIvW
w water elevation ampiitudt at open boundary,
$ = temperature *Q
P. water nufac:e slope;
it = wave number.
A horizontal density gra&=M
. n = general wd culvilinear coordinate system.
P = Wader deelnsitT•
P. = air density;
p, = water density average;
jS = vertically averaged of water density;
p' - vertically density diffeueuct;
or = vertical coordim t transformation;
era = empirical diffusion constant;
a. = sclunidt nutlet;
T; = bottom shear stress;
+!: = wind dxw sit:
= mean scalar titgr.
0. r - gnat wowinatt system;
tl - wave firoquetlay; sod
art - vertical velocity in c transform coordinate.
12 / JOURNAL OF HYDRAULIC ENGINEERING / JANUARY 1997
l:
f
A
February 5, 2001
MEMORANDUM
TO: John Dorney .
FROM: Eric Fleek t/1
SUBJECT: Mason Inlet Relocation (NCDWQ# 12569)
1. RESPONSE TO #2: While their response did expand upon impacts, monitoring, and minimization to i??
Piping Plover and its habitat (as requested), their response did not include similar information (as
requested), for Sea Beach Amaranth. Please include this information.
2. RESPONSE TO #10 and #11: While they are conducting wetland mitigation beyond what is required
the amount set aside for potential impacts to coastal marsh as a result of increased erosion due to
higher water velocities, higher surface water elevation, and increased levels of boat wake is only 0.5
acres. There are approximately 4000' feet of coastal marsh adjacent to Mason's Creek that will be
subject to these new physical conditions. Given this large amount of area, they should either increase
the amount of mitigation to offset these potential losses, or they should be required to monitor the loss
in these wetland areas. Given the uncertainty of requiring them to conduct yet more mitigation than is
lawfully required, compelling them to monitor these wetland areas for erosion would likely be the most
prudent option. Figures 5-1, 5-2, 5-3 (Attachment D) indicate many areas will experience increases in
water surface elevations and Figures 5-4, 5-5, and 5-6 (Attachment D) indicated many areas will
experience increased water velocities. Given these model predications, monitoring these wetland areas
for loss as a result of these forces seems very reasonable. There were not direct predictions for Mason
Creek itself for these parameters. Even if they conducted models for these forces in Mason's Creek
itself, I'd argue that the wetland monitoring should be required regardless given model uncertainty and
the large potential for damage.
3. RESPONSE TO #16: I asked for vegetative stabilization for their beach berm. Their response is that
they would "comply with any forthcoming requests from the stat arding plajngs-€ei'-stabilization
purposes". I will assume this is our responsibility (or perhaps AMA? itfer way, perhaps Steve
could devise a species list and planting scheme. If not, perhaps we should coordinate with LAMA. I
would recommend a combination of American Beachgrass (fast growing groundcover) and Sea Oats-
although at what density I'm not certain.
4. RESPONSE TO #18: In my 7/14/00 Memorandum I asked for a definition of what the applicant
considered "eroded" versus "not eroded". Their 1/8/01 response does not include this information-
only data regarding how much beachfill they are proposing on Figure 8 Island. This information (either
photographic or surveyed elevation data) should be required before giving the applicant unchallenged
approval for 8,500' of beachfill.
Comments Regarding the Physical and Biological Plan

t/

is not. p b
3. RESPONSE TO #15: Biological monitoring of the marsh area must be for a minimum of five years. 1
1. REPONSE TO #5: In my 7/14/00 Memorandum I requested that the applicant consider measuring
changes in water velocity. Their 1/8/01 response notes "there may be value in comparing the predicted
velocities for the WQMAP model simulations (representing the final project design) to the monitoring
"point in time" velocity profiles (using an ADCP instrument) to assess and correlate model
predictions". I would request that such correlation measurements be required. The frequency at which
these measurements are taken could be left to the applicant-subject to our approval. In addition,
similar measurements should also be taken for the simulated water surface elevations in order to
"correlate" these "model predictions". Given these physical forces and how they can directly impact
sensitive coastal marsh, such model correlation confirming measurements seem prudent.
2. RESPONSE TO #7: The applicant is proposing biological monitoring along two of six transects. I
would request that a minimum of three (ideally four) of six transects be assessed. While the actual
methods used for sam ling the transects themselves is adequate the number of transects being sampled
r
July 14, 2000
MEMORANDUM
TO: Milt Rhodes
THROUGH: John Dorney
FROM: Eric Fleek
SUB ECT: MASON INLET RELOCATION-REVISED EA COMMENTS
(DENR#1019, DWQ#12569)
Based on a review of the revised EA and the accompanying comments (Dated 6/23/00
from Chris Gibson), the following additional clarifications are needed before a FONSI
can be issued. Experts on coastal dynamics should be given an opportunity to review this
revised EA. We plan to contact them directly and ask for their comments. Any additional
comments which may be generated by these experts need to addressed by the applicant
prior to the FONSI. The numbers below are direct responses of the 6/23/00 letter
addressed to Milt Rhodes from the applicant's representative, Chris Gibson.
While the revised EA does provide some data on annual erosion rates on Figure 8 Island,
the numbers seem contradictory. For example, on Page 3-5 the EA notes: "the southern
shoreline of the island experienced an erosion rate of 13.6 ft per year between 1984 and
1989". Then on Page 3-6 the EA notes that "the documented high rate of erosion
represents average wind and wave conditions", and that "immediately updrift of Mason
Inlet, the island's shoreline eroded at 4.0 feet per year over the 1984-1989 period. In
comparison, past long-term shoreline erosion rates on Figure 8 Island were 3 to 4 feet per
year adjacent to the island's inlets". Presumably, that portion of Figure 8 Island
"immediately updrift of Mason Inlet" is the southern edge of the island. It is also
"adjacent to the island's inlet". Is this area eroding at 13.6 ft per year or at 4.0 ft. per year
from 1984-1989? In addition, it seems that 4.0 feet per year is not much different than the
"past long-term" erosion rate of 3-4 feet per year. Please clarify these points. In addition,
are there any data more recent that 1989?
2. The revised EA does provide plan views of the project area in regards to the
renourishment project (Figure 3.1-3.3 Appendix P, Sheet 8 of Appendix M). end'x
"Q' does address Pining Pli,???rs and Q__ Beach Amaranth irr?nact_ s but no
or anisms (while tin habitat are Proposed for impacts to these species.
Please elaborate on any mitigation offered for impacts to the_„ sP r___?cnu_rces. A itionally,
the information in the EA regarding impacts to invertebrate beach fauna associated with
the renourishment project is treated only on the scale of North Carolina as a whole. These
calculations are based on 3% of the total North Carolina coast impacted (0.0015%) as a
result of this individual project instead of providing data on what percentage of the
Figure 8 Island beaches will be impacted versus that which will not be. Please provide
this information.
The revised EA provides maps depicting generalized habitats (e.g., Sea Beach Amaranth,
coastal wetlands, supra-tidal, inter-tidal, and subtidal, etc.) in relation to project activities
but these figures do not depict the Water Classifications (e.g., SC, SA, ORW, PNA, etc.)-
-as originallyrequested, in relation to project activities. Please provide this information.
4. The EA is correct in asserting that no SAV beds (emphasis added) occur south of Pender
County but the statement that "no SAV's are known to occur south of Pender County" is
incorrect. As per UNCW researchers, SAV (Zostera marina) does occur in the
Wilmington area in small (0.5 m2) patches. In addition, the applicant's 6/23/00 response
i
necessity for the use of more than one island." The completed delineation and survey of these
islands and the proposed mitigation plan (including elevations, plan view maps, descriptive
narrative, and monitoring plans) should be submitted to NCDWQ for final approval.
16. By beach berm NCDWQ assumes that this feature is a supra-littoral structure. If so, it will be
placed in areas of similar elevation of dunes. Given the highly dynamic and erosive nature of these
areas, it seems likely that some sort of vegetative stabilization would be desirable to facilitate
stability in the structure and thereby promote additional natural vegetative colonization. Please
elaborate on why no stabilization is deemed necessary.
17. Noted. Please include a copy of the physical monitoring plan with the FONSI/Revised EA.
18. Sheet "8" of Appendix "M" does not provide the requested.information. Please reference
elevations inside and outside of the proposed 8500' beach fill area. The EA on Page 5-25 noted
that the "beach renourishment will occur only in eroded areas". Please define (in map and plan
view forms) what is being defined as "eroded areas" and what are not defined as "eroded areas".
Please provide full-sized plans (at least 1:200) depicting contours of both current and proposed
conditions within the 8500' proposed beach fill area.
19. Noted.
20. There is no data provided supporting any assertion that there is a water quality problem existing in
the immediate project area. Claiming that dredging Mason's Creek will improve water quality in
areas where it is apparently not impaired should not be claimed as a "positive cumulative impact'
as is contended on Page 5-51 on the revised EA.
21. Again, there is no data provided suggesting that any shellfish beds in or near the project area
(whether they are in PNAs or not) are impaired due to restricted flows from Mason's Creek. As
above, claiming that dredging Mason's Creek will improve shellfish beds when there are no data
supporting that nearby/adjacent PNAs/shellfish beds are impaired is inappropriate. In fact,
dredging Mason's Creek will directly destroy the PNA/shellfish habitat observed during DWQ's
earlier site inspection.
22. As the revised EA notes, the increased tidal prism of the proposed project will (as per model
simulation) "result in a slight increase (i.e., 4 percent) in total tidal flux through the three inlets"
(i.e., Masonboro, Mason, and Rich Inlets). Please translate what an approximate 4 percent increase
in tidal flux means in terms of increased/decreased tidal heights. In other words, will tidal ranges
increase 4 percent for high tides and decrease 4 percent for low tides? Please clarify. Tidal height
information is important for determining potential impacts and alterations in coastal marsh habitat.
Physical and Biological Monitoring Plan Comments
1. Noted. However, NCDWQ believes that an annual monitoring frequency (after the I't year post-
construction quarterly monitoring period) is more appropriate than the 18 month and 24 month
monitoring (again, after the 1S` year post-project). Is this 18/24 month monitoring frequency
(preceding the final annual sampling for the project's life) a standard period for this type of
project?
2. Noted.
3. Appendix "P", Section 3.2.2 Page 27 of the Revised EA does not address absence of finfish
monitoring. Please see #4 below.
4. NCDWQ understands the ephemeral nature of finfish. However, a species list before and after the
project would be useful. Please conduct such a study. Please explain the "benthos utilization"
methodology more completely. For example, how will these areas be sampled, at what seasonal
AIM
APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA, INC.

January 8, 2001 10 2001
Mr. John Dorney l - -
Division of Water Quality
1621 Mail Service Center
Raleigh, N.C. 27699-1621
Re: Mason Inlet Relocation Project, DENR #1019, DWQ #12569
Dear John:
This letter is to respond to your Revised EA Comments sent in a memorandum to Milt Rhodes on
July 14, 2000. Unfortunately, we did not receive a copy of these comments from the State until
December 21, 2000. Many of the issues and concerns you expressed in this July 2000 letter have
since been addressed during the federal EA review process with the various federal agencies as
coordinated by the USACOE.
Additionally, 15 copies of the final wetland mitigation plan were submitted on December 14, 2000 to
the USACOE for distribution to all the state and federal review agencies. Please contact Jeff Richter
if you have not received a copy of this Plan. The voluntary expansion of the wetland restoration
area, flushing channel design and other aspects of the proposal were discussed in meetings with the
USACOE and USFWS during final plan development. The following items correspond to the
numbered comments within your July 14, 2000 memorandum:
1) The most recent, comprehensive monitoring data set at Figure 8 Island beaches is
the May 1990 study conducted by William Cleary, Ph. D. for the period between 1984
and 1989. In reviewing your comments concerning the erosion rate documentation
for Figure 8 Island, we agree that the values presented in the text discussion were
confusing and need further clarification. In this regard, we offer the following
clarification. The southernmost 4,100 ft of Figure 8 Island eroded at rates between
7.5 and 19.5 ft per year for the dune line and the mean high water line, respectively,
between 1984 and 1989. The 8,000 ft shoreline segment immediately north of the
aforementioned 4,100 ft segment, eroded at a rate of 4 and 15 ft per year for the
dune line and the mean high water line, respectively, between 1984 and 1989. On
Page 3-5 of the EA as you noted "the southern shoreline of the island experienced an
erosion rate of 13.6 ft per year between 1984 and 1989" which erroneously averaged
the actual range of rates given by Dr. Cleary (i.e. 7.5 and 19.5 which was averaged to
equal 13.6). Further, on Page 3-6 of the EA as you noted "immediately updrift of
Mason Inlet, the island's shoreline eroded at 4.0 ft peryear" this should read "further
updrift of Mason Inlet, the island's dune line eroded at 4.0 ft per year". .
201 North Front Street, Suite 508
992651-Domey-010801 Wilmington, North Carolina 28401
TEL [phone] FAX [phone]
Mr. John Dorney
January 8, 2001
Page 2
As you noted, past long-term erosion rates of 3 to 4 ft per year (using the
dune/vegetation line movement as a reference point) is consistent with the changes
documented by Dr. Cleary in this study.
nThe final Biological Assessment for the project was submitted to the USACOE and
I 1 determined to be complete for purposes of the Section 7 Consultation process now jrn
underway with USFWS. USFWS is currently preparing their Biological Opinio 5ILyr Ja/`
addition, as a result of consultations with USFWS, the applicant is ro mg to
reduce the width of the sedimentation basin by 100 ft in order mi ' s atial
im ac s to intertidal shoal areas utilized y s orebir s inclu ing piping plover. T e
app is also coordinatin an ex anded i in lover monitorin ro
ro ' "mil ?ahlP nPPded data on the usage of this and other suitable habitat areas,
alo_..3r n +hP row unty shoreline. l At 4vt = % IS d ? Sjce? ??' S r Mt ?a/? / ,,
moc4in3 be N1ccoG2 { S4% \ '{ar
The length of the beachfront on FiguretiIs and is 5 miles. The length of the proposed
beach nourishment area is 1.61 miles. Therefore, with regard to the comment on A^c{
invertebrate beach fauna, the percentage of the island's oceanfront to be impacted oA
by the project is 32.2%. "?9
3) All of Middle Sound is classified as SA/ORW according to the North Carolina 04mayj,;?
Administrative Code. Land Management Group (LMG) has requested and received 6*0*-
from North Carolina Marine Fisheries (NCMF) information on the limits of Primary
Nursery Area for the Mason Creek area. The enclosed PNA boundary line mapping
was drawn by NCMF staff on a February 1, 1998 aerial photograph and then digitized
by LMG for presentation (Attachment "A").
4)
No SAV beds or small SAV patches have been observed by our firm within the
project area.
It is acknowledged that only shellfish resources were surveyed and quantified within
the Mason Creek Project area and that this does not represent the overall benthic
community. However, our observations indicated that within the heavily shoaled main
run of Mason Creek, benthic organisms overall were visually sparse in comparison to
the small adjoining tidal creeks where shoaling was less evident. It is also
acknowledged that the dredging within the Mason Creek project limits will indeed
destroy infaunal and epifaunal benthic organisms present.
5) Noted
6) N/A
7) N/A
8) Noted
9) N/A
99265J-Domey-010801
rld,
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Mr. John Dorney
January 8, 2001 S
Page 3 C1 (?
Oft-
10) The final wetland Mitigation Plan contains an additional 0.5 acres of wetland
restoration based on the potential for indirect impacts to the remaining marsh edge
within Mason Creek by boat wakes and other undefined secondary impacts. There is
an additional proposed 2.8-acre voluntary restoration area in excess of the required
3.8 acres and the 0.5 acres above, bringing the total restoration area up to 8.7 acres.
.?- r. 'd f'II /f 1 r 'ksr 5 w+-?- Mcn !
11 See # 1 o abov a Mo-5A,', at t e cV( or--
1 ) N/A Q( 5 ?o / -e/vv bz A. eve o e a o-4
l??,,? O c ,p ?a Ca n? c j f } (?c?sLY f zp?ti,? ,
13) It is agreed that the planned sediment basin will convert shallow JVal habita to sub- /
tidal habitat. Consideration should also be given to the proposed minimization of wk6 er
basin width in item # 2 above as well as the amount of shallow sandy bottom created
landward of the inlet fill area as part of the project. i /t (?I?-.
14) N/A
z
15) Agreed. The final Mitigation Plan, currently in distribution by the USACOE to
1D?
commenting state and federal agencies, is available for DWQ review. ?e 06 (V&V
ry) -5 -to
?•i'`Pl? i (16)? The filled Mason Inlet area below the mean high water line will beco?e?property of E-
n v the State of North Carolina and as a result, the Count intends to comply with an Igya - Vu(u
?Q Y Y
forthcoming requests from the state regarding plantings for stabilization purposes. water vd(outr
0? 17) The physical monitoring plan is shown in Figure 3-1 of the Inlet Management Plan 5?1G2
kioA (Appendix P of the EA). These figures have been attached for your reference. In
S4v?''?` a? Fn;?6' addition to the physical monitoring for inlet management shown in this figure, profiles `
A S
,y !t will be conducted in Mason Creek at 200-ft intervals near the entrance to the AIWW -A s
5
L ??y ? to the sedimentation basin, and at 100-ft intervals across the Intracoastal
q ? stn Waterway extending 1000 feet north and south of the AIWW entrance to Mason r\ \CV1t1N
ctee
6?>>t Creek. Refer to Attachment "B", modified Figure 3.1 (sheets 1 through 3). Q,/e t
1 Although portions of the Figure 8 Island beachfill area are more highly eroded than
others, the entire 8,500 feet of beachfront is considered eroded and in need of
renourishment. The fill area will be constructed such that the seaward edge of theU
berm is uniform in shape and fill quantities will vary from 35 to 50 cubic yards per `R<y2
?? t d linear foot in order to produce a consistent seaward alignment of the shoreline. Plan
r(, view drawings, at a scale of 1 inch equals 100 ft, illustrating the proposed beachfill K h
cX templates are attached. In addition, a sheet showing typical cross sections is S-rf" L
n attached in lieu of the requested contour maps. The beach profiles surveyed provide
enough information for planning purposes and volumetric analysis, but do not extend
far enough seaward to provide complete documentation of nearshore contours.
?d \ Refer to Attachment "C", Project drawing sheets 7, 8, 9, & 18.
e? Ofo. r
19) N/A .-l
99265!-Domey-010801
S'z\
?,JOAO,
rr,
s 5(
Mr. John Dorney
January 8, 2001
Page 4
20) Agreed. Positive cumulative impacts should not be claimed relating to water quality
without supporting data. However, the discussion relating to the enhanced and
maintained estuarine flushing through the Mason Creek channel from Atlantic ocean
waters is still relevant.
21) There is no reference within the EA to impaired shellfish beds caused by restrictive
flows from Mason Creek. The extremely limited shellfish population (as documented
by two shellfish surveys and by NCMF staff observation) within the Mason Creek bed
is due to the dynamic sand shoaling which provides a poor substrate for shellfish. As
stated above, it is agreed that within the Mason Creek project area, dredging will
destroy this limited shellfish resource. Following the project, it is anticipated that the
functioning sediment basin will serve to significantly reduce the shoaling potential
within the creek that will provide for a more stable shellfish substrate environment
outside the immediate dredged area. It is acknowledged that the dredged area itself
may be subject to maintenance as required by conditions over time that would
eliminate any shellfish population in that particular area.
22) To clarify, the 4 percent increase in tidal flux refers to the volume of water passing
through the inlets during a given tidal cycle. There is not a direct correlation, (i.e. one
to one relationship), between the change in tidal flux and the change in surface water
elevations. Projected changes in water surface elevation for high tide and mean tide
levels at various locations within the estuary are diagramed in Figures 7-2 and 7-3 of
the attached Hydrodynamic Modeling Report, Attachment "D" (ATM, August 2000).
Copies of these figures are included for your convenience.
Re: Physical and Biological Monitoring Plan Comments ,-'"
ally for the second
1) The in fre uency will be quarterly for the first =oc=cuonths,
Year and aljLLth??er__eafter. us, moni o s 9 months, 12 months; T$-months, 24 months, 36 months, 48 months, etc. after
completion of the project. Please accept our apologies for ny confusion in the
wording of the June 23 response. --
2) N/A
3) Monitoring of finfish populations is not proposed. The intensive nature of such a
study is considered beyond the scope of the proposed biological monitoring. Most of
the finfish utilizing these waters are transient with high temporal and spatial variation
corresponding to a wide range of physical and biological parameters. Covariance of
these factors would make it extremely difficult to identify a species response to
project activities. Therefore, a pre- and post-project survey or `species list' would
yield little viable data relating to population responses to project activities.
4) Refer to Number 3 for response to comments regarding finfish populations. The EA
states that epibenthic utilization will be evaluated via species lists and relative
abundance. These are qualitative observations to be conducted at or near low tide
99265J-Domey-010801

Mr. John Dorney
January 8, 2001
Page 5
during each monitoring event. Observations of epibenthic organisms will not be
statistically analyzed. Again, due to the intensive nature of epibenthic sampling and
the variability of these populations in response to a wide range of parameters,
statistically valid quantitative studies of population responses to project activities will
not be conducted.
DWQ comment regarding potential disturbance to quadrats from monitoring is noted.
Due to the frequency of vegetative sampling (once per year), we believe there will be
no sampling disturbance to the vegetative quadrats. Infaunal assessments
(described in Response #7) will be conducted outside of the permanent vegetative
quadrats at randomly-generated distances and bearings. The randomized selection
J 5)of these areas will ensure minimal disturbance and sampling artifact.
Noted. Yes, "point in time" velocity profiles for a single tidal cycle can be collected
during the physical monitoring events, in the immediate project area, at a reasonable
expense. However, collection of data to include "... Mason Creek and its tributaries..."
as requested in the DWQ comments dated December 22, 1999 for a full neap and
spring tidal cycle woul be costly and of limited value to assessing post-cons
Project Performance. here may va ue in comparing pre acted velocities forth
fWdMMD,e simulations (representing the final project design) to the monito
"point in time" velocity profiles (using an ADCP instrument) to assess and correlat
the model predictions. [•y? I ?d I (Jov-, d0o(4t-- f(NI'+G/
___-_0CQn)q t Ii J dt l.pa
7 Biological monitoring will include a b thi
m2 area will be sampled at ea observati
300 ft from creek edge) al g two of the
field and subsequent lab wo es sa
lk?
Sampling the two transects once annually
will yield a total 30 samples to be analyze
at arandomly-generated distance and
quadrat. The upper two inches of the
square-ended spade and sieved through
from sediment and vegetative material. I
formalin solution with Rose Bengal stain
identification to the lowest reliable tax0
organisms utilizing the marsh substrate
vi be provided in each monitoring report.
Species richness and abundance will be
8) N/A
c infaunal urvey. Three rep'l'icates-ofD._-
on{i at 5 it, 50 ft, 100 ft, 150 ft, and
six transe s. The intensive nature of the
all six transects cost-prohibitive.
coinciding with other biological sampling)
each year. The replicates will be located
bearing from the permanent vegetative
marsh substrate will be removed with a
0.5 mm screen mesh to separate infauna
faunal species will be preserved in a 5%
nd transferred to a benthic laboratory for
omic level. A species list of infaunal
cal ated from these data.
1; ? 1 i,Gc? 3 d ?
2.- e< pcr 4W" ? ? 9
L -M/
9) Noted. Pre-construction baseline monitoring of existing conditions is the preferred
method. If the sequencing of the permitting process does not allow for baseline
biological monitoring, an adjacent undisturbed marsh area will be monitored as a
reference site.

99265]-Domey-010801
v )%
Mr. John Dorney
January 8, 2001
Page 6
10) N/A11) N/A
110 Noted. If it is determined at an alternative time that transplanting of Spartina is
necessary, the formula/methodology prescribed in DWQ's comments will be
employed.
12? N/A
134 Noted. See the final mitigation plan to be distributed by the USACOE.
C14)S iological monitoring of the marsh area will be conducted for a minimum of three to a yip
maximum of five years post-construction. Benthic infaunal sampling and qualitative
observations of epibenthic and wildlife species will be conducted once per year to
coincide with the vegetative monitoring and sediment sampling. If no significant S?
perturbations are evident in the sample plots, then monitoring will be concluded at
the end of the second year. /
Please contact me with any questions you may have regarding this information. /W $ 0?
Enclosures: Attachment "A" - PNA boundary map
Sincerely,
Karyn M. Erickson, V.P., P.E.
Applied Technology and Management, Inc.
Steve Morrison, Environmental Consultant
L?l
Land Management Group, Inc.
d}O
Sam/
Attachment "B" - Modifed Figure 3.1
Attachment "C" - Project Drawings 7, 8, 9, 18
Attachment "D" - Hydrodynamic Modeling of Mason Inlet
and the Middle Sound Estuary
cc: Doug Huggett, NCDCM
Dave Weaver, New Hanover County
Greg Thompson, New Hanover County
Jeff Richter, USACOE
99265J-Domey-010801
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PPLIED TECHNOLOGY & MANAGEMENT
Shell Island ?? OF NORTH CAROLINA. INC.
Figure 3-1 (Sheet 2 of 3) ya,,zd r
Physical Monitoring Plan '
Survey Monuments and Lines '
PPLIED TECHNOLOGY & MANAGEMENT
Shell Island ?YLrv%/tO??JYIPiJ2?p?i ?df2blG?pl??6 OF NORTH CAROLINA, INC.
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I J/ .
DATE: 8/20799
BEACH FILL
SECTION BP-1
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA
J. JLL J. ft
SHEET 29 201 LM NORTH FRONT ST., SURE 201
WIINGTON, NC 2B101
[phone] FM(91D)762-6250
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DATE: 8120 99 rtx-
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HORIZONTAL DATUM: NC G ID NA(D 83 COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY STATE: NORTH CAROLINA
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SECTION N - N AT: WRIGHTSVILLE BEACH AND
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HORIZO L ATI; NC G IL trAD 83 COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY STATE: NORTH CAROLINA
- 414 CHESTNUT ST
DATE 8/20f99? WILMINGTON, NC 28401 SHEET 23 zol NORTH FRONT ST., SUITE 701
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VERTICAL DATUM: NGVD (MS}'? 1829)
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CHANNEL SECTION
SECTION K-K'
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
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STATE: NORTH CAROLINA
J. JL.L J. T.L
201 NORTH FRONT S .,_ SURE 201
DATE: 8/20%99_ zL-(-
NEW HANOVER COUNTY
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HORIZONTAL DAT M: N 1twD N.AD 83 COUNTY OF: NEW HANOVER
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VERTICAL DATUM: N,-,VD (tASL 1329)
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COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY STATE: NORTH CAROLINA
414 CHESTNUT ST
WILMINGTON, NC 28401 z°' WIMNCTO7 NC2 B 01
SHEET 16 9tnV67-OBOD F0(910)762-
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VERTICAL DATUM: NGVD (MSL jAZ9j SECTION E-E FIGURE 8 ISLAND
HORIZONTAL DATU : NC GRID?4AL b3 COUNTY OF: NEW HANOVER
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WILMINGTON NC 28401 201 NORTH FRONT ST., SURE 201
DATE 8/20/99 SHEET 14 WILMINGTON, NC 26401
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SECTION D-D' AT: WRIGHTSVILLE BEACH AND
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HORIZONTAL DATA NC G D NAD 83 ? COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY STATE: NORTH CAROLINA
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DATE: 8/20?9S b a G °` ? WILMINGTON, NC 28401 SHEET 3 201 NOWH MOW ST., SUFTE WILMINGTON, N (910)]6 D20Go7AX 9C2Bf00)]621-6251
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HORIZONTAL DA UM: N: ?'R u NAD 3s COUNTY OF: NEW HANOVER
NEW HANOVER COUNTY STATE: NORTH CAROLINA
414 CHESTNUT ST
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tE NEW HANOVER COUNTY STATE: NORTH CAROLINA
(o l ?? 414 CHESTNUT ST
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DATE: 8/24/99 SHEET 1 910)762-0800 FW (910)762-625
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DATE: 8/20/99
CHANNEL SECTION
SECTION A-A'
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA Ak"
2D1 NORTH FROM ST.. SURE 201
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AT: WRIGHTSVILLE BEACH AND
VERTICAL DATUM: NGVD (4pL 1929) SECTION B-B FIGURE 8 ISLAND
HORIZONTAL DATUM: NC Gplp NAC 83 COUNTY OF: NEW HANOVER 0 -m NEW HANOVER COUNTY STATE: NORTH CAROLINA rIff"TR .md
414 CHESTNUT ST rrrr•z
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DATE: 8/20/99 i 011 __ c91m7 2-M D NM(910)762-6250
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VERTICAL DATUM: NGVD (MSL?929)
HORIZONTAL DATUM: NC G IIIy HD 83
DATE: 8/24/99 a (o
PROPOSED PROJECT
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA
.L JLJL.LT.L
201 NORTH FRONT ST., SURE 201
SHEET 9 WILMINGTON, NC 78401
[phone] FM(910)762-625
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AT: WRIGHTSVILLE BEACH AND
VERTICAL DATUM: NGVD (MSL?1929) FIGURE 8 ISLAND
HORIZONTAL DATUM: IjC GRl AD 83 COUNTY OF: NEW HANOVER
NEW CNOVER COUNTY STATE: NORTH CAROLINA A
DATE: 8/24/99 g ' &p Q WILMINGTON, NC 28401 SHEET 7 2 uN°10N. NC 28 0? 201
(910, 762-0800 F"(910)762-62
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VERTICAL DATUM: NGVD SL 1929) FIGURE 8 ISLAND
HORI TAL DAT' M: N rZ10 NAD 83 COUNTY OF: NEW HANOVER ArM
.A,
41NEW4 HA CHESTNUT ST COUNTY STATE: NORTH CAROLINA rrx-
824 99 a ?? WILMINGTON, NC 28401 SHEET 8 zof NORTH FRON fit., SURE 201
6 F NO 26401
DATE: (910)]622--0800 0600 FAX[phone]
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APPLICATION BY:NEW HANOVER COUNTY
VERTICAL DATUM: NGVD (',t4Ln1225}
HORIZONTAL DATUM: NC GRI AD 133
USACE # \
DATE: 8/20/99
PROPOSED PROJECT
SHEET INDEX
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA
201 NORTH FRONT ST., SURE
SHEET 6 WILMINGTO%)N9 C 28401
[phone] 10)762-
NOTES:
HORIZONTAL COORDINATES BASED ON
26ATE PLANES, NAD 83 ,
2) ATHY SURVEYS CONDUCTED BY M
ETWEEN JUNE Y, 1999.e
3) TLAND DELINEATIO P ED Bil-A
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M NAGEMENT GROUP, C. ANp S E.- ED B
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APPLICATION BY:NEW HANOVER COUNTY EXISTING CONDITIONS PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
VERTICAL DATUM: NGVJ (MSS, 1929) FIGURE 8 ISLAND
HORIZONTAL DATUR NC G ,O ; COUNTY OF: NEW HANOVER
R NEW HANOVER COUNTY A" I
STATE: NORTH CAROLINA
DATE 8/24/99
&/q 414 CHESTNUT ST
WILMINGTON, NC 28401 201 NORTH FRONT ST., SURE 201
SHEET 5 WILMINGTON. NC 28401
[phone] FA%(910J]62-625
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APPLICATION BY:NEW HA' O ER COUNTY
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EXISITING CONDITIONS
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
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PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
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STATE: NORTH CAROLINA fycl
201 NORTH FRONT ST., SURE
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DATE:
a
EXISTING CONDITIONS
SHEET INDEX
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
STATE: NORTH CAROLINA rTm
SHEET 2
201 NORTH FROM ST.. SUITE
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Form DCM-MP-1
APPLICATION:"
(To be completed by all applicants)
1. APPLICANT
a. Landowner:
Name New Hannvor ('rnin+y
Address 414 Chestnut Street
City Wilmington . State NC
Zip 28401 Day Phone [phone]
Fax [phone]
b. Authorized Agent:
Name Applied Technology & Mgmt
of North Carolina, Inc.
Address 201 N. Front St. , Suite 201
City _ Wilmington State NC
Zip 28401 Day Phone [phone]
Fax [phone]
c. Project name (if any) -Mason T n l 6,t
Ref drat i nn Prn3er•i-
NOTE: Penrd! will be issued in name of landowner(s), and/or
project name.
2. LOCATION OF PROPOSED
PROJECT
a. County New Hanover
b. City, town, community or landmark
Wriahtsvi 1 1 P Raarh and
Island E1r° °'
C. Street address or secondary road number
d. Is proposed work within city limits or planning
jurisdiction? _ X Yes -No
e. Name of body of water nearest project (e.g, river,
creek, sound, bay) Macon T n 1 pt
Mason-Creek
3. DESCRIPTION AND PLANNED USE
OF PROPOSED PROJECT
a: List. all development activities you propose (e.g.
building a home, motel, marina, bulkhead, pier, and
excavation and/or filling activities.
Excavation across inlet corridor,
easement on Figure 8 Island;
excavation at Mason Creek; filling
existing location of Mason Inlet;.
beachfill at Figure 8 Island
b. Is the proposed activity maintenance of an existing
project, new work, or both? New Work
c. Will the project be for public, private or commercial
use? Public
d. Give a brief description of purpose, use, methods of
construction and daily operations of proposed
project. If more space is -needed, please attach
additional pages. _ See attached

vo A-v nzroc
Form DCM-MP-1
4. LAND AND WATER
CHARACTERISTICS
m. Describe existing wastewater treatment facilities.
N/A
a. Size of entire tract _ 79.8 Acres (D r d q e
and fill- areas)
b. Size of individual lot(s) N/A
c. Approximate elevation of tract above MHW or
NWL Varies -21 MHW to +51 MHW
d. Soil type(s) and texture(s) of tract Shoals are
unconsolidated sand (SP & SP/SM). Spit
n. Describe location and type, of discharges to waters
of the state. (For example, surface runoff, sanitary
wastewater, industrial/commercial effluent, "wash
down" and residential discharges.) Hydraulic
dredging with slurry discharges a
sites for beachfill and Mason
Inlet infilling.
o. Describe existing drinking water supply source.
is N/A
new an san unconsolidated sand. Mature
t1dal,marsh is silty clay loam.
e. Vegetation on traces G= a r t. i n ;q A l t a rn i f l n r a,
S. Patens,Borrichia Frutascens, Distichlis
pica a, a icornia pp., nio a aniculata,
Cakile Endentula, Hydrocotyle Spp-
f. Man-nRjeN features now on tract
5. ADDITIONAL INFORMATION
g. What is the CAMA, Land Use Plan 'land
classification of the site? (consult the local land use plan.)
X Conservation Transitional
X Developed Community
Rural Other
h. How is the tract zoned by local government?
R20 s
i. Is the proposed project consistent with the applicable
zoning? X Yes - No
(Attach zoning caornpliance certifiaue, if applicable)
j. Has a professional archaeological assessment been
done for the tract? Yes X No
If yes, by whom? SHPO Guidance Letter
received/no professional assessment
k. is rtlrie project relo& edr in a National Registered
Historic District or does it involve a National
Register listed or eligible property?
Yes x No
1. Are there wetlands on the site? X Yes No
Coastal (marsh) X Other
If yes, has a delineation been conducted? Yes
(Anach documentation, if available)
In addition to the completed application form, the
following items must be submitted:
• A copy of the deed (with state application only) or
other instrument under which the applicant claims title
to the affected properties. If- the applicant is not
claiming to be the owner of said property, then
forward a copy of the deed or other instrument under
which the owner claims title, plus written permission
from the owner to carry out the project.
• An accurate, dated work plat (including plan view
and cross-sectional drawings) drawn to scale in black
ink on an 8 1/2" by 11" white paper. (Refer to
Coastal Resources Commission Rule 71.0203 for a
detailed description.)
Please note that original drawings are preferred and
only high quality copies will be accepted. Blue-line
prints or other larger plats are acceptable only if an
adequate number of quality copies are provided by
applicant. (Contact the U.S. Army Corps of
Engineers regarding that agency's use of larger
drawings.) A site or location map is a part of plat
requirements and it must be sufficiently detailed to
guide agency personnel unfamiliar with the area to the
3 d. Description and Planned Use of Proposed Project
The purpose.of this project is to protect homes and upland property at north Wrightsville
Beach from erosion related losses caused by the continued southerly migration of Mason
Inlet. Sand will be excavated from Mason Creek between the ICWW and Figure 8 Island
and transported via pipeline to the existing Mason Inlet and the southerly beaches of
Figure 8 Island.
A hydraulic dredge will be used to excavate material from Mason Creek through the new
inlet location across Figure 8 Island. The sand slurry will be pumped through both
floating and land based pipeline to the locations of fill placement. Pipeline will be
located within established corridors extending to the south end of Figure 8 Island
continuing north to the southernmost 8,500 feet of developed beaches on Figure 8 Island.
A corridor will be established and marked with flagging to lay out pipeline (floating and
fixed lines) between the area(s) of excavation and the stockpile and fill area. The
stockpile area is proposed to be located at the south end of Figure 8 Island, contiguous to
the channel bank at the existing inlet.
r.1 7 7
"J, T
?j `rte
j
Form DCM-MP-1
site. Include highway or secondary road (SR)
numbers, landmarks, and the like.
• A Stormwater Certification, if one is necessary.
• A list of the names and complete addresses of the
adjacent waterfront (riparian) landowners and
signed return receipts as proof that such owners
have received a copy of the application and plats
by certified mail. Such landowners must be advised
that they have 30 days is which to submit comments
on the proposed project to the Division of Coastal
Management. Upon signing this form, the applicant
further certifies that such notice has been provided.
Name See attached list
Address
Phone
Name
Address
Phone
Name
Address
Phone
• A list of previous state or federal permits issued for
work on the project tract. Include permit numbers,
permittee, and issuing dates.
None
• A check for $250 made payable to the Department of
Environment, Health, and Natural Resources
(DEHNR) to cover the costs of processing the
application.
• A signed AEC hazard notice for projects in
oceanfront and inlet areas.
• A statement of compliance with the N.C.
Environmental Policy Act (N.C.G.S. 113A - 1 to
10) If the project involves the expenditure of public
funds or use of public lands, attach a statement
documenting compliance with the North Carolina
Environmental Policy Act.
6. CERTIFICATION AND PERMISSION
TO ENTER ON LAND
I understand that any permit issued in response to this
application will allow only the development described in
the application. The project will be subject to conditions
and restrictions contained in the permit.
I certify that to the best of my knowledge, the proposed
activity complies with the State of North Carolina's
approved Coastal Management Program and will be
conducted in a manner consistent with such program.
I certify that I am authorized to grant, and do in fact,
grant permission to representatives of state and federal
review agencies to enter on the aforementioned lands in
connection with evaluating information related to this
permit application and follow-up monitoring of the
project.
I further certify that the information provided in this
application is truthful to the best of my knowledge.
This is the c2 6 day of a-u , 19 9q
Print Name Kar34n M- Fri rkcnn. PK
Applied Technol y & Mgmt.
Signature Of North ?aroli Inc.
Please indicate attachments pertaining to your proposed
project.
X DCM MP-2 Excavation and Fill Information
DCM MP-3 Upland Development
DCM MP-4 Structures Information
DCM MP-5 Bridges and Culverts
DCM MP-6 Marina Development
NOTE: Please sign and date each attachment in the
space provided at the-bottom of each form.
z i%

5. Names of adjacent waterfront owners:
1. Shell Island Homeowners Association
c/o Shanklin & McDaniel
214 Market St
Wilmington, NC 28401
[phone]
2. Geo Henry HutafF Trust No. 2
c/o David Ward
Ward & Smith
1001 College Court
PO Box 867
New Bern, NC 28560
(252).633-1000
3. State of North Carolina
Department of Administration
State Property Office
Go Joe Henderson
116 West Jones Street
Raleigh, NC 27611
[phone]
4. Bruce Cameron
2219 Blythe Road
Wilmington, NC 28403
[phone]
5. Town of Wrightsville Beach
Tony Caudle, Town Manager
321 Causeway Drive
Wrightsville Beach, NC 28480
[phone]
6. Figure 8 Beach Homeowners' Association
c% Edward S. Barclay, Jr., President
15 Bridge Rd
Wilmington, NC 28411
[phone]
i ?
?? : ? V
1' r_ ^ ` 2 1999 J
r
?••° •v cam. Il•'1P ;i ?:."'S -M ENT
Form DCM-MP-2
EXCAVATION
AND FILL
(Except bridges and culverts)
Attach this form to Joint Application for CAMA Major
Permit, Form DCM-MP-1. Be sure to complete all
other sections of the Joint Application that relate to this
proposed project.
Describe below the purpose of proposed excavation or
fill activities. All values to be given in feet. .
Average Final
Existing Project '
Leneth Width Denth i]rnth
Access
channel
(MLW) or (NWL)
Canal
Inlet
Boat
basin
Boat
ramp
Rock
groin
Rock
breakwater
Other Beach
(Excluding
shoreline
stabilization)
Revised 03195
3400 70 +2 to
-8
GVD NGVD
2100 500 Varie -10
NGVD

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C} ,t-V?Jii?.:
0,00 50 - +4 to +8 to
.100 -6 -6
1. EXCAVATION
a. Amount of material to be excavated from below
MHW or NWL in cubic yards ag.i ,.0.00 _ Y
b. Type of material. to be excavated urnconsolidated
fine/medium grain sand, SP SP/SM'
classified soils
c. Does the area to be excavated include coastal
wetlands (marsh), submerged aquatic vegetation
(SAVs) or other wetlands? X Yes No
d. Highground excavation in cubic yards _ 29.0, 000 c?
2. DISPOSAL OF EXCAVATED
MATERIAL
a. Location of disposal area 1. Mason Inlet and
2. southerly 2 miles of developed
shoreline at Figure 8 Island
b. Dimensions of disposal area 1. 38.7 acres anc
2. varies 50 to 10 ' x 10,000,
c. Do you claim title to disposal area?
Yes X No
If no, attach a letter granting permission from the
-owner.
d. Will a disposal area be available for future
maintenance? X yes No
If yes, where? Construction easements
across lands south of inlet
Form DCM-MP-2
e. Does the disposal area include any coastal wetlands
(marsh), SAVs or other wetlands?
Yes X No
f. Does the disposal include any area in the water?
X Yes No
3. SHORELINE STABILIZATION
a. Type of shoreline stabilization N/A
Bulkhead Riprap
b. Length
c.- Average distance waterward of MHW or NWL
d. Maximum distance waterward of MHW or NWL
e. Shoreline erosion during preceding 12 months
(Source of inform Pion)
f. Type of bulkhead or riprap material
g. Amount of fill in cubic yards to be placed-below
water level
(1) Riprap
(2) Bulkhead backfilI
h. Type of fill material
i. Source of fill material
4. OTHER FILL ACTIVITIES
(Excluding Shoreline Stabilization)
a. Will fill material be brought to site?
X' Yes No (Hydraulic
If yes,
(1) Amount of material to be placed in the
waterA) 395,700 cy B) 30-8,300 c
(2) Dimensions f fill area A ) 1, 700 - x
11000, B3 f
75'
(3) Purpose of fill A) F; i , Px; g+ ; „
inlet B) Nourish beach
b. Will fill material be placed in coastal wetlands
(marsh), SAVs or other wetlands?
- Yes X No
If yes,
(1) Dimensions of fill area
(2) Purpose of fill
5. GENERAL
a. How will excavated or fill material be kept on site
and erosion controlled? Long dikes
parallel to shoreline-
b. What type of construction equipment will be used
(for example, dragline, backhoe, or hydraulic
dredge)?
Hydraulic dredge, Excavators and
Bulldozers
c. Will wetlands be cr;,ssed in transporting equipment
to project site? Yes X .No
If yes, explain steps that will be taken to lessen
environmental impacts.
Karyn M. ckson, P.E.
Applicant r Proj
Sig cure
placemen
Revised 03/95
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COOS E ri_ f?fi^il?Lt"i: er?ENT1
Appendix I
O^ O
North Carolina Department of Cu tural Resources
Jamos B. S9tfl Je, rovcmor j. Dkelskm of Ardt4= sud Hiptory
Betty Ray MdCAin, Seaaeeoty kff=Y 3_ Ctow. A'ueetor
December 13, 1996
r
Steve Morrison
Environmental Consultant
Land Management Group, Inc.
P.O. Box 2522
Wilmington, NC 28402
Re: Request for Information conjoerning the
preparation of environmentO assessment for the
relocation of Mason's Inlet,. New Hanover
County
Dear Mr. Morrison:
At your request, members of our Underwater Archaeology Unit reviewed the
proposed relocations of Mason's Inlet. Historically there has been an inlet in The
general project location. It has beim known as Mason's Inlet. Queen's Inlet, and
Barren Inlet. '
In the Underwater Archaeology Unit's Shipwreck research files there are references
to two vessels lost in The Inlet: The Caldwell, a schooner lost in 1848, r.tnd The
Marea, a gasoline-powered freighrfboat lost in 1926. In 1993, staff members
inspected the remains of a wooden sailing ship, 0002MA1, in Masons Inlet
approximately two hundred yards north of the Shell Island resort- Other unrecorded
shipwrecks may exist in the project area.
A review of historical records indicates that Mason's inlet was shallow and seldom
used for navtgaition. In addition, the inlet has been very unstable and prone to
move rapidly north and south between Shelf Island and Figure Eight Island- It
appears that during the nineteenth century the inlet was most often in its current
location.
Based on this information, the proposed excavation of the inlet approximately
3,500+ feet north of the Shell Island resort occurs in an area than holds only low to
moderate potential for containing submerged cultural remains. We, therefore,
recommend that no underwater sojohaeoiogical investigation be conducted in
connection with the dredging portion of the project.
The closure of the existing inlet m15y affect shipwreck site 0002MA3. While in the
long term this may benefit the eito by covering it with protective sands, we are
concerned about the methods whi)Ch may be used to close the inlet- In some
cases, construction activities mayid1sturb or destroy historic shipwreck remains-
We, therefore, recommend that wr: _ be provided with detailed plans for closure as
109 E=t Jones Strict -lltaldgh, North Carolina 27541-2847
1 - E 2 11199 i JL
COASTAL 101ANAGEMVIENT
1 a Jl I f I N ?
J! 7i?
Steve Morrison
December 13, 1996, Page 2 .I
they become available. Staff merriibers will attempt to pinpoint the present location
and nature of site OOO2MAl to asst project engineers in avoiding damage to the
shipwreck.
We would tike to notify you that tijiis project should be undertaken with extreme
caution, both during excavation of tithe new inlet alignment and irt-fif}ing of the
Current alignment. If during construction submerged rhsterieis are encountered,
work should move to another ar"*Iahd our Underwater Archoerology Unit be
contacted immediately (918-468.2). A staff member will be sent to make an
assessment of tha remains and d ••ermine the proper course of action.
The above comments are made pursuant to Section 108 of :the National Historic
Preservardon Act and the Advisory+jCouneil on Hietoe#6 Preservation's Regulaf ions
for Compliance with Section 106 dodified at 36 CFR Part 600.,
Thank you for your cooperation ar4d consideration_ if you have questions
concerning the above comment, piss contact Renee Gledhill-Earley, erivironmernal
review coordinsto?r, at 9191763-4263.
cerely, ,
t?'?+r acs"' ,
David Brook
Deputy State Historic Preservratiorr'Officer
DB;sfw
cc, H. F. Vlok. North Carolina Dijspartment of Transportation
.r
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C'©A : - '?
ATM
APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA, INC.
November 5, 1999
Mr. Edward Brooks
NC Division of Coastal Management
127 N. Cardinal Drive Ext.
Wilmington, NC 28401
RE: Mason Inlet Relocation Project
Dear Mr. Brooks:
7 t V
n
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3
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The Mason Inlet Relocation Project's proposed Mitigation Plan and proposed Physical
and Biological Monitoring Plan are enclosed for your consideration.
If you have any questions or require supplemental information for either of these plans,
please feel free to call Steve Morrison or me.
Sincerely,
Karyn M. Ericks , P.E.
Vice President
Cc: Doug Hugget, NC Division of Coastal Management
Gregory R. Thompson, P.E., New Hanover County
201 North Front Street, Suite 201
Wilmington, North Carolina 28401
TEL [phone] FAX [phone]
Physical and Biological
Monitoring Plan
Submitted to:
North Carolina Division of Coastal Management
U.S. Army Corps of Engineers
Applicant:
i I ?? 1` { y i? in r\
New Hanover County
Prepared by:
Applied Technology and Management of North Carolina, Inc.
Land Management Group, Inc.
October, 1999
)qh+
APPLIED TECHNOLOGY & MANAGEMENT
OF NORTH CAROLINA. INC.
MASON INLET RELOCATION PROJECT
PROJECT SUMMARY
8 1999
' ,?? S D1? '0I'?' OF
MANAGEMENT
On behalf of New Hanover County, Applied Technology and Management of North Carolina,
Inc. (ATM) has submitted a permit application to the Division of Coastal Management (DCM)
and the U.S. Army Corps of Engineers (USCOE) for activities associated with the proposed
relocation of Mason Inlet. The purpose of this project is to protect homes and upland property
at the northern end of Wrightsville Beach from erosion losses resulting from the continued
southerly migration of Mason Inlet. Sand will be excavated from Mason Creek between the
ICWW and Figure Eight Island and transported via pipeline to the existing Mason Inlet and the
southern oceanfront beaches of Figure Eight Island. An Environmental Assessment (EA)
assessing existing environmental conditions and potential project impacts has been prepared
and distributed to participating regulatory agencies for review. The following plan outlines
various components of the physical and biological monitoring that will be used to evaluate
potential impacts associated with the inlet relocation project. The EA should be referred to for
additional information regarding project design and potential impacts to environmental
resources.
BEACH AND OFFSHORE PROFILES
Beach and offshore profiles shall be measured at 20 reference monuments to be established
along the Figure 8 Island, Mason Inlet and Wrightsville Beach shoreline adjacent to the Mason
Inlet Relocation Project Area. Profiles will extend along the shore normal azimuths, from the
backbeach (west of the existing dune or berm feature) approximately 1,500 feet offshore (to the
-25-foot NGVD contour). The average spacing between monuments will range from 250 feet
near the inlet to 1,000 feet at distances greater than 1,500 feet from the new and the closed
Mason Inlet location.
In addition, profiles at the adjacent beaches monuments will also be similarly measured. The
adjacent survey limits will extend approximately 3,000 feet north of the relocated inlet
monuments (MI-1 to MI-5) and 5,000 feet south of the inlet (MI-11 to MI-20). The adjacent
beaches profiles will allow monitoring of sand spreading and movement adjacent to the
relocated Mason Inlet.
Beach profiles will be performed immediately before and after construction. Additional surveys
will be performed at 6 months, 1 year, and 2 years following project completion. Additional
annual surveys will be performed if the North Carolina Division of Coastal Management (DCM)
determines them to be necessary. Profiles will also be conducted following significant storm
events during the 24-month monitoring period following completion of construction.
201 North Front Street, Suite 201
Wilmington, North Carolina 28401
TEL [phone] FAX [phone]
-1-
99265A-HydrolBiologMonitoringPlan102599pce
Vertical and horizontal control will be referenced to NGVD 1929 and North Carolina State Plane
Coordinate System (NAD 1927), respectively. Survey line azimuths will be identified by
magnetic bearing. Survey data will be submitted to the DCM in the form of cross-sectional
profile plots and on 3.5" disk in the DCM designated digital format. A report will be submitted
for each post-construction survey which will document the results of volumetric and shoreline
change analyses to the Inlet, sedimentation basin and the ebb tidal shoal(s) in the Project area
and along adjacent beaches.
INLET AREA BATHYMETRY
Bathymetry at the interior inlet will be measured prior to construction, immediately following
construction, and annually thereafter for the 24-month monitoring period. The surveys will
consist of 30 lines,spaced approximately 150 feet apart. The lines will run approximately 1,000
to 1,500 feet following the long axis of the inlet (east to west). The data and volumetric change
analyses will be included in the 1-year and 2-year post-construction hydrographic monitoring
reports indicated above. ,
SURFICIAL SAND SAMPLING
Surface sand samples will be collected immediately following construction and concurrently with
the 12 month beach profile surveys. Sand samples will be collected along eight (8) longshore
transects. Sand samples will be collected at elevations ±10, +5, 0, -5, -10, and -15 feet NGVD.
Samples will be analyzed using standard ASTM procedures to determine the grain size
distribution (8 sieves). Results will be submitted to the DCM with an analysis of the longshore
and cross-shore adjustment of the beaches and inlet channel banks and the ebb shoal.
AERIAL PHOTOGRAPHY
Color, vertical aerial photographs shall be flown. along the Project shoreline at the time of each
monitoring survey. The scale of the photographs shall be 1 inch equals 200 feet. The flight line
shall begin 3,000 feet north of the inlet and proceed southward at distance of 10,000 feet, 7,000
feet south from the new inlet location.
Each photograph shall include the entire beach, nearshore environment, and sufficient upland
features (i.e., beach-fronting buildings, roads, etc.) to determine the location of any photograph.
The shoreline location in any image should be approximately half way across the width of the
photograph. Consecutive photographs shall have sufficient overlap (approximately 20%) to
identify common points of interest. Photographs shall be taken prior to 2:00 PM to avoid
building shadows cast towards the beach.
Local predicted tides will be used to determine flight times so subsequent photography events
will occur during similar times in the tidal cycle. Photographs will not be rectified, but horizontal
ground control.will be established by setting sufficiently sized aerial targets (4' x 4') on the
reference monuments in the days prior to the flight. In the event that a monument is either not
visible due to vegetation or located in an area of heavy traffic, the aerial target shall be offset
from the monument along the profile azimuth. This offset distance and azimut ill
the target-setting party's field notes for use during any subsequent photographic n -c V E
I
rov U 8 1999
,Ml &
99265A-H drolBior vi?o Coastal Engineers, Jcientists & Management Consultants DI
\/I L??OA1 OF pce
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BIOLOGICAL MONITORING
The goal of the biological monitoring plan is to assess and document potential effects of project
activities on primary productivity, faunal utilization, and substrate texture/organic content of
marsh areas adjacent to the proposed work zone. Pre- and post-construction monitoring will
provide quantitative data and qualitative observations that can be used determine if any
deleterious effects to the marsh habitat are directly attributable to the inlet relocation project.
The extent to which monitoring parameters will be affected depends on various conditions (e.g.
the character of the dredged material, tidal and current regimes, etc.) and any system
responses will likely be distributed in a linear fashion from Mason Creek.
MONITORING PARAMETERS
Selection of monitoring parameters has been based upon those factors potentially impacted by
project activities and those readily sampled and evaluated. The following monitoring elements
have been selected:
(1) Spartina stem density
(2) Mature (>30 cm height) Spartina stem height
(3) Percent sand, silt, and clay of surface substrate
(4) Percent organic content of surface substrate
(5) Sedimentation rate?'
(6) Benthic macroinvertebrate utilization
(7) Wildlife utilization
R 'ECEHVIR
t: V 0 199
1, . D
DIVISION! OF
UAKIAGEVIENT
Evaluation of each of these parameters is discussed in the following section.
BIOLOGICAL SAMPLING AND ANALYSIS METHODOLOGY
Sampling efforts will focus on the area of potential impact where biota and physical conditions
(e.g. soil texture) are most likely affected by project activities and associated perturbations such
as altered flooding regime and sedimentation. As discussed earlier, any perturbations will
manifest in system responses distributed linearly from Mason Creek. Therefore, three
permanent 300-foot monitoring transects will be established along a north-south axis on both
sides of Mason Creek (totaling six transects). Four one-meter square quadrats for each
transect (located 50, 100, 150 and 300 feet away from Mason Creek) will be sampled for stem
density and height of Spartina. The quadrat located furthest from Mason Creek will serve as
the control plof for each transect. (Refer to the enclosed map depicting monitoring transects
and plots.)
Sediments will be characterized according to percent sand/silt/clay and percent organic matter.
A composite sample will be collected for the 50, 100, and 150-foot plots. One sample will be
collected for each control plot. In addition, metal rebar installed flush with the sediment surface
prior to project construction will used to evaluate sediment deposition and/or loss over time for
each plot.
Faunal utilization of marsh habitat will be evaluated through species lists and relative densities
of epibenthic macroinvertebrates and wildlife along transect corridors. Indirect evidence and
.Arm I
99265A-HydrolBioRSglilZZon7UZS?J?c?" Coastal Engineers, scientists & Management Consultants
direct observation will be used to document the presence of a species within the transect
corridor. Each transect corridor will extend 150 feet away from Mason Creek and will be 3 feet
wide. Separate control transect corridors (150 feet by 3 feet) will be established in an east-west
orientation as depicted on the enclosed map.
Each survey will incorporate photographic documentation depicting site conditions along each
transect corridor. During each monitoring period, close-up and panoramic views will be
photographed at designated stations.
Pre-dredging and the post-dredging mean values of each parameter will be statistically
compared using Analysis of Variance (ANOVA)/paired t-tests or Wlcoxon signed rank tests.
Ninety-five percent confidence intervals will be used to determine statistically significant
differences of means (means will be significantly different if confidence intervals do not
overlap). Proximal and/or distal changes (if any) in sedimentation rates, stem density and/or
stem height will also be statistically determined.
BIOLOGICAL MONITORING SCHEDULE
The effects of any perturbation on vegetative conditions will be most pronounced and
detectable during active growth and development. Therefore, monitoring will occur during the
middle of the growing season (June/July) once each year subsequent to project completion for
a duration of two years. Sampling for baseline conditions will be conducted in the June/July
prior to project initiation (provided that there is sufficient time once the project permit has been
obtained). An immediate pre-construction survey (conducted within 30 days prior to project
initiation) will detect changes resulting from storm events during the elapsed time between
June/July and the start of project construction. A total of four monitoring events will be used to
determine if impacts are directly attributable to project activities. All the parameters discussed
in the previous section will be evaluated during each monitoring event.
REPORT DOCUMENTATION
Monitoring reports documenting site conditions and findings will be prepared and submitted
annually to the Division of Coastal Management, the U.S. Army Corps of Engineers, and the
Division of Water Quality by September 15"' (following the June/July monitoring event). The
following information will be provided in each report:
(1) Project overview
(2) Site parameters monitored
(3) Methodology used to evaluate parameters
(4) Data analysis
(5) Summary of findings
(6) Prints of photographs at specified stations
(7) Maps depicting location of transects and sampling plots.
TM (C TM IV Im L__'
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99265A-Hydro18io1k5g7lFn,r,9 4oA Coastal Engineers, scientists & Management Consultants
MITIGATION PROPOSAL DRAFT
MASON INLET RELOCATION PROJECT
NEW HANOVER COUNTY, APPLICANT
LAND MANAGEMENT GROUP, INC.
OCTOBER 1999
APPLIED TECHNOLOGY &
MANAGEMENT, INC.
ECEIVE
1:13v u 3 '2.99

ECENE
R Nov 0 8 1999
MASON INLET RELOCATION PROJECT SUMMARY DIVISION
"`r)AQTA1 ??4?!AGFRI ENT
On behalf of New Hanover County, Applied Technology and Management of North Carolina, Inc.
(ATM) has submitted a permit application to the Division of Coastal Management (DCM) and the
U.S. Army Corps of Engineers (USCOE) for activities associated with the proposed relocation.of
Mason Inlet (refer to Figure 1, `Location Map'). The purpose of this project is to protect homes
and upland property at the northern end of Wrightsville Beach from erosion losses resulting from
the continued southerly migration of Mason Inlet. Sand will be excavated from Mason Creek
between the ICWW and Figure Eight Island and transported via pipeline to the existing Mason
Inlet and the southern oceanfront beaches of Figure Eight Island. An Environmental Assessment
(EA) assessing.existing environmental conditions and potential project impacts has been prepared
and distributed to participating regulatory agencies for review. The following proposal outlines
restoration efforts as mitigation for anticipated wetland impacts associated with the inlet
relocation project. The EA should be referred to for additional information regarding project
design and potential impacts to environmental resources.
MITIGATION CONSIDERATIONS
Avoidance and Minimization: The project design of the relocation of Mason Inlet has sought
to avoid and minimize impacts to existing marsh habitat. However, a continuous 170-foot wide
channel will need to be constructed through an area of recently accreting marsh on the south side
of Mason Creek. This channel is essential for re-establishing the ebb flow dominance of Mason
Creek over Banks Channel, ultimately resulting in a more "stable" inlet location and minimizing
the frequency of inlet maintenance activities. Therefore, the proposed design will impact 2.9 acres
of volunteer Spartina alternij7ora habitat (refer to Figure 2, `Proposed Project'). As described in
the EA, this area of marsh is characterized by a lower level of habitat value and overall
productivity than the marsh to the north side of Mason Creek (classified as ORW). Project design
of the inlet relocation has sought to avoid impacts to the mature stands of S. alternfflora.
Therefore, no excavation will take place within the mature, well-established marsh habitat on the
north side of Mason Creek.
Wetlands Impacted: An area of 2.9 acres of recently established S. alterniora habitat will be
impacted. This area represents approximately 5.6 % .of the 51.9 total acres to be excavated for the
inlet relocation project.
Proposed Mitigation: In order to mitigate for the impacts to coastal marsh area, the applicant
proposes to plant S. alterniora seedlings on suitable intertidal flats adjacent to the project area in
coordination with the Division of Coastal Management (DCM). Mitigation is proposed at a 2:1
ratio; therefore, a total of 5.8 acres of S. alternflora marsh will be restored.
Mitigation Goals and Objectives: The objective of the proposed wetland mitigation is to double
the spacial extent of marsh impacted by the planned Mason Creek dredging work (2:1). In
Project Location and
Current Location of
Mason Inlet (1999)
i;uc a?
I", 111 ,Ill ,{+1 @ ,., h I Tf.

f
Note: Shoreline features digitized from USGS Wrightsville
Beach Quadrangle Mop 5452IIINE (1970)
APPLICATION BY:HEW MOVE I.! :OuNTY LOCATION MAP PR
N
i?4000
Scale in Feet
AT: WRIGHTSVILLE BEACH AND
CDOT k_ Figure I FIGURE 8 ISLAND
COUNTY OF. NEW HANOVER
1 1 C1q NEW HANOVER COUNTY STATE: NORTH CAROLINA
414 CHESTNUT ST
DATE: 8/24/99 WILMINGTON, NC 28401
_ SHEET 1 R
v1ca:
1 HORIZONTAL COORDINATES BASED ON
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APPLICATION BY:NEW HANO':=R COUMn
VERTICAL DATUM: NGVD (MSLA929)
HORIZONTAL DATUM: NC GRI
MD 83
T
DATE:
PROPOSED PROJECT
Figure 2
NEW HANOVER COUNTY
414 CHESTNUT ST
WILMINGTON, NC 28401
PROPOSED: MASON INLET RELOCATION
AT: WRIGHTSVILLE BEACH AND
FIGURE 8 ISLAND
COUNTY OF: NEW HANOVER
?
STATE: NORTH CAROLINA OLINA i s-a<-.LT1
SHEET 9
addition, planting of S. altern jlora on suitable intertidal shoals will help to restore marsh areas
severely impacted by recent hurricanes. The long-term goal of the mitigation - r04.ect is tom,
establish marsh habitat functionally equivalent to the impacted areas.,
SITE CHARACTERIZATION 1999
Intertidal areas suitable for coastal marsh restoration have been identified based upon tidal ?range,
??
substrate characteristics, and exposure to wave energy. Areas recentl niT
y damaged by overwash
events associated with tropical storm systems have been specifically targeted for restoration
activities. Collectively, recent storms have damaged or buried approximately 20 acres of
productive marsh Between the Shell Island Resort and Mason Creek.
In light of these considerations, two primary mitigation areas have been selected. As depicted on
the enclosed site design map (Figure 3), these intertidal flats are located along the edge of the
interior marsh lagoon system approximately 1500 feet south of the proposed new inlet location.
The distance from the mouth of the proposed inlet will help minimize exposure to high velocity
currents that could threaten the stability and success of the Spartina plantings. In addition, the
location of the potential restoration areas are subjected to relatively low wind fetch distances.
Wind fetch distances of less than 1.0 nautical mile have been demonstrated to limit damage from
wave action significant enough to eliminate the need for maintenance planting (Broome, Seneca
and Woodhouse, 1986).
SITE ELEVATION
Subsequent to project completion and equilibration of channel side slopes, beachfront sediments,
and currents; grades in the mitigation area will be confirmed to ensure that surface elevations do
not deviate significantly from the pre-construction intertidal contours. Specific planting zones will
be .selected in areas exhibiting gradual slopes (1-3%) in order to maximize the intertidal area and
dissipate wave energy. Extremely flat or irregular surfaces will be avoided, for these areas tend to
favor localized hypersaline conditions unsuitable for plant growth (Broome, 1990). Elevations and
tidal range will simulate that of natural reference marshes. This type of mitigation will not warrant
the use of water control structures or sediment and erosional control measures.
PLANTING PLAN
Nursery stock seedlings of S. alternflora grown specifically for wetland creation and restoration
projects in this region will be planted on 2' spacings in areas of suitable elevation,
microtopography, and substrate characteristics. Mature seeds will be collected from local
Spartina stands during the September or October immediately after the permit for the inlet
relocation project has been obtained . Seeds will be refrigerated, threshed, and then stored in a
container filled with potting soil and salt water (35 parts per thousand) at 35 to 40° F. Seedlings
will then be ready for planting on the mitigation site during April of the next calendar year. Actual
planting locations willbe within sandy sediments of the upper half of the local tidal range. The
mitigation area will comprise 5.8 acres (corresponding to approximately 60,000 seedlings).
An alternative restoration scheme involves transplanting individual Spartina plants from the
existing marsh stand to be excavated. However, this option is considered problematic. The
construction sequence involves excavating the Mason Creek segment before closing the existing
inlet. Since the proposed mitigation area is situated directly to the west of the existing inlet,
transplants would be subjected to direct wave action and high velocity flow, severely
compromising plant health. Temporary storage of transplanted Spartina during inlet relocation is
not considered a viable option given the inherent difficulties of handling and maintaining
transplants. Therefore, planting nursery stock seedlings is considered to be the most advantageous
method of restoring' Spartina habitat.
Once the existing inlet mouth has been closed, flow velocities should be reduced in the primary
overwash area. Spartina growth would no longer be hampered by prohibitive flow rates or an
excessive shifting sediment load. As such, it is anticipated that the planted wetland area will
survive with limited mortality. Recruitment of new Spartina growth within the mitigation area will
be promoted by active rhizomal proliferation and seed dispersal of adjacent natural stands.
SOIL AMENDMENTS
Each seedling will receive a small amount of Osmocote (or equivalent) slow-release fertilizer
within the planting hole to accelerate initial growth. Slow-release fertilization is considered
particularly advantageous in sandy substrates (which exhibit a lower capacity to retain applied
nutrients) and has been demonstrated to be an effective practice in marsh restoration and creation
projects (Broome, 1990). No further soil amendments are proposed at this time. The addition of
organic matter to the substrate has been demonstrated to enhance rhizome growth within an
artificial, controlled mesocosm (Padgett and Brown, 1998). However, the field application of
organic material would involve incorporating peat into the upper soil through mechanized tilling
over the entire mitigation area. This would disturb the stability of the soil profile, thereby making
the sandy substrate more susceptible to erosion during tidal exchanges and threatening the
immediate stability of the planted materials.
SITE PERFORMANCE CRITERIA
Site success criteria are used to evaluate the development of a created or restored wetland in
relation to stated project goals and objectives. Monitoring of various biological and
physiochemical parameters will help demonstrate the relative success of a compensation site.
These `performance' criteria are agreed upon by the applicant and the respective regulatory
agency(s) as part of the permitting process.
Since this compensation project seeks to restore marsh habitat through plant' r ?U ?e? INVE
Spartina seedlings, the primary success criteria will be: .?1d
0 8 1999 t
1i 0a
?.. ..,,
"Demonstrated survival rate of plantings and naturally colonized individuals to exceed
70% after the second monitoring year. "
Additional site success criteria. commonly utilized for other wetland compensation projects are not
suitable for this project. For instance, soil development (i.e. percent organic matter, nutrient
composition, bulk density, porosity, etc.) of created and restored tidal marshes usually can not be
demonstrated to simulate the substrate of natural reference marshes within the stated monitoring
period (Broome, 1990).
MONITORING PLAN
Periodic monitoring of site performance criteria will be conducted by the applicant at prescribed
intervals to evaluate project development. Parameters such as percent survivorship of plantings
and soil texture/organic content will be quantitatively evaluated in three permanent 25 meter-
square plots representative of the planting area. The comers of each plot will be staked with metal
rebar installed flush with the sediment surface. Therefore, relative sediment deposition and/or
sediment loss within the mitigation area can be evaluated. Qualitative observations of faunal
(including epbenthic and wildlife) habitat use will be recorded. In addition, photographic
documentation (close-up and panoramic views) of plantings will occur at specified stations. An
initial "as-built" survey will be conducted immediately following completion of plantings. This
survey will include the limits of natural Spartina stands that exist adjacent to the planting area.
Monitoring will then be conducted once annually during each subsequent April/May for a duration
of three years documenting fulfillment of performance criteria. Monitoring reports will be
prepared and submitted to the DCM, COE, and DWQ by August 15'' of that year. The following
information will be provided in each report:
1. Reference permit number
2. Summary compensation site project goals and objectives ECEHVE
3. Overview of the compensation 4. Site parameters monitored i
5. Methodology used to evaluate parameters C-mow X999 -
6. Data analysis
7. Summary of findings ?, S a e c4 R r,. ?`
-' •-a .rA1T
8. Maintenance measures
9. Remedial measures
10. Prints of photographs at specified stations
11. Maps identifying adjacent natural marsh habitat, planting zones, areas monitored,
transects, etc., as appropriate.
Reports will document annual findings and evaluate the development of the project site with
respect to performance criteria and target goals.
Annual site monitoring will help to identify maintenance issues as they arise. Successful wetland
compensation will require maintenance activities as needed throughout the duration of the
monitoring period. Maintenance activities may include plant replacement and/or fertilization. If
performance criteria are not met, reasons for deficiencies will be determined and appropriate
remedial action will be conducted.
ECEHVE
t';'; 0 81999
I D
DIVISION OF
-%nne-rnl hAAK1nr-%CAPNT
LITERATURE CITED
Broome, S. W., E. Seneca and W. Woodhouse, Jr. 1982. Building and Stabilizing Coastal Dunes
with Vegetation. Pub. UNC Sea Grant 85-05.
Broome, S. W. 1990. Creation and restoration of tidal wetlands of the Southeastern United States.
Pp. 37-72 in Kusler, M.E. (eds.) Wetland Creation and Restoration: the Status of the
Science. Island Press, Washington DC.
Padgett, D.E. and J.L. Brown. 1999. Effects of drainage and soil organic content on growth of
Spartina alterniflora (Poaceae) in an artificial salt marsh mesocosm. American Journal of
Botany. 86('5). 697-702.
e rsyy
,04, OF
AGEME T
Figure 3
Potentiai Wetland Mitigation Sites
1999
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l?1'tdNOlMf?l{? ?7C7??FOILKIi/t?b? APO/-'ED 77C?-,N GY MA4ACF.VFN"
: ?'-

NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
BILL HOLMAN
I?.-SECRETARY
k-
K E R R T. STEP
$ - DIRECTORµ
January 11, 2000
Certified Mail
Return Receipt Requested
Greg Thompson
• New Hanover County
414 Chesmut Street
Wilmington, N.C. 28401
r: J R, _'
v
Subject: Mason Inlet Relocation
New Hanover County
NCDWQ# 991112
To Whom It May Concern:
After a review of the Environmental Assessment, site visits, and
discussions with the applicant's agents the North Carolina Division of Water
Quality has determined { as described in 15A NCAC 2H .0506(h) } that the
wetland mitigation proposed as part of this project does not meet the
definition of restoration and is rather wetland enhancement. Therefore, the
requirement for 1:1 restoration or creation (15A NCAC 2H .0506(h)(6)]
would not be met. Secondly, after careful review of the proposal and a
comprehensive site inspection we believe that this project cannot be permitted
with the proposed dredging of Mason's Creek as is required by 15A NCAC
2H.0507(e). Since a practical alternative exists-namely relocation of the inlet
without dredging Mason's Creek, this alternative either removes or drastically
reduces the need for wetland mitigation.
As a result, if you cannot submit alternative information as detailed
above for your proposed project the North Carolina Division of Water Quality
will have to move towards denial of your 401 Water Quality Certification
once the SEPA process is completed. If there are any questions regarding this
matter please feel free to contact Mr. Eric Fleek at 919-733-6946 or myself at
919-733-1786. -

x

Y`

Cc: Wilmington DWQ Regional 9flice
Wilmington Office, Corps of Engineers
Central Files
File Copy
Wilmington Field Office Corps of Engineers
Doug Hugget, North Carolina Division of Coastal Management
Steve Morrison, Land Management
Karyn Erickson, ATM
Gloria Putnam, NCDWQ.
Ron Ferrell, NCWRP
1N. AMERILA.
2 0 1 0
1621 MAIL SERVICE CENTER, RALEIGH, NORTH CAROLINA 27699-1621
website: esb.ehnr.state.nc.us PHONE [phone] FAX [phone]
AN EQUAL OPPORTUNITY / AFFIRMATIVE ACTION EMPLOYER - 50% RECYCLED/10% POST-CONSUMER PAPER
United States Department of the Interior
FISH AND WILDLIFE SERVICE
Raleigh Field Office
Post Office Box 33726
Raleigh, North Carolina 27636-3726
December 20, 1999
Colonel James W. DeLony
District Engineer, Wilmington District
;.a
U.S. Army Corps of Engineers ?ie,
Post Office Box 1890 50 QJ
Wilmington, North Carolina 28402-1890
Attention: Mr. Jeffrey Richter
(k5l
Dear Colonel DeLony:
Per our November 29, 1999 letter to you, the U.S. Fish and Wildlife Service (Service) is pleased
to provide the District Engineer with documents describing the "no project" environment related
to Action I.D. No. 199901052. The applicant, New Hanover County, proposes to stabilize
Mason's Inlet; mine sand, and nourish adjacent beaches by maintaining an artificially dredged
channel, installing a sand plug in the existing channel, and establishing sediment traps and
storage sites between Shell Island and Figure Eight Island north of Wrightsville Beach, New
Hanover County, North Carolina.
This document provides supplemental information submitted pursuant to, and in accordance
with, provisions of the Fish and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C.
661 et seq.) and the Endangered Species Act of 1973 (87 Stat. 884, as amended; 16 U.S.C. 1531
et seq.).
The Environmental Analysis (EA) submitted in conjunction with the application significantly
misstated the reasonably foreseeable environment without the project. As implied in the
proposal's purpose and need, the current environment is transitional. If no project is authorized,
according to the applicant, Mason's Inlet will continue migrating to some point between the
current location and Moore's Inlet. The structures and infrastructure in the path of the migrating
inlet will be relocated or otherwise removed at the expense of the county and private property
owners. The "no project" baseline from which all other alternatives must be evaluated is that of
a restored barrier island with all human structures and infrastructure removed, and with partial
restoration of the integrity of the soundside marshes and ecosystem (i.e., in addition to the
restoration of the barrier islands' undisturbed form and structure, natural processes would be
largely unimpeded). Thus, the future "no project" environment is a restored barrier island,
unstabilized inlet, and partially restored sound.
To describe this future environment, we are attaching two reports: (1) the Service's 1981 Final
Fish and Wildlife Coordination Act Report (Report), written prior to the development of this
portion of Shell Island; and, (2) selections from the Department of Commerce's and North
Carolina Department of Natural Resources and Community Development's (now Department of
Environment and Natural Resources, Division of Coastal Management) 1984 Final
Environmental Impact Statement and Draft Management Plan for the Proposed Masonboro
Island Component of the North Carolina National Estuarine Sanctuary (FEIS). We include the
Masonboro Island report because it describes a nearby undeveloped barrier island adjacent to
Wrightsville Beach. However, the jetties at Masonboro Inlet, maintenance and expansion of the
authorized channels, beach nourishment of Wrightsville Beach, and mismanaged sediment
bypassing scheme mean that Masonboro Island's ecosystem must be considered degraded. While
the FEIS describes an undeveloped barrier island, reviewers should bear in mind that the FEIS is
describing an ecosystem which has less functional and structural integrity than the system which
is reasonably foreseeable on Shell Island under the "'no project" alternative. Further, scientific
advances have been made in the 20 years since the Report and FEIS were prepared. Additional
references are available and barrier island/sound ecosystems in general can supplement the two
documents. We believe the combination of the Report (pages 2-6; and 9-22; and the attached
Planning Aid Report), FEIS (pp. 54-67; and appendices 5,6, 7, and 8 [pp 293-330]), and
literature synthesis provided below establish a reasonable information base for evaluating the
environmental impacts of the proposal.
In our opinion, the "no project" alternative provides significant benefits to fish and wildlife
resources, federal trust species, water quality, and the human and economic environment. The
"no project" alternative will restore the ecological integrity of aquatic resources of national
importance and could partially fulfill loggerhead sea turtle recovery objectives in North
Carolina'.
We note that the FEIS states that "Masonboro Island is the best example for its typology in the
state of North Carolina" (pp. 45). The significance of the reasonably foreseeable future
environment under the "no proj ect" alternative is nowhere more clear than in that statement.
Natural processes are impeded on Masonboro Island by sand mining, jetties, inadequate sand
bypass schemes, and maintenance of navigation channels. We can only speculate on the
unproved example the restored Shell Island ecosystem and partially restored sound could
provide. The environmental baseline will enhance educational and research opportunities for
local educational facilities, as well as provide additional study areas for birdwatching and other
recreational pursuits (see especially FEIS, pp. 127-131). Based on the available information, we
believe the New Hanover County Board of Commissioners will recognize that the "no project"
alternative provide opportunities which they have unanimously endorsed in the past. As recorded
'National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1991. Recovery
Plan for U.S. Population of Loggerhead Turtle. National Marine Fisheries Service, Washington,
D.C.
2
in the FEIS (pp. 109-110), the Commissioners supported efforts to keep Masonboro Island
undeveloped and "pristine" because of it's "unique" and "significant value" in educational,
economic, recreational, and scientific terms. They recognized that the provision of "public
services on undeveloped barrier islands would ... be prohibitively expensive when compared with
service costs in other areas of the county;" and the unsuitablitiy of barrier islands like Shell
Island for development ("Masonboro Island is dynamically unstable due to inlet migration and
long-term erosion, which would endanger the establishment of permanent communities").
We stress that through the 'imaginative use of mitigation banks, tax credits, and hazard mitigation
grants, the "no project" alternative need not adversely affect the current property owners of the
affected area. If designed to allow current owners the use of existing structures until death or
erosion limits the habitability of the structures, and if payments are made at currently assessed
values, the environmentally preferable "no project" alternative would be realized with little or no
social dislocation. The "no project" alternative is consistent with Executive Orders 11988
Floodplain Management and 11990 Protection of Wetlands.
The environmental baseline provides additional benefits to fish and invertebrates not described in
the Report and FEIS. These include unquantified improvements in water filtration efficiency and
the diversity and integrity of habitats. The restoration of diverse habitats, linkages, and the
diversity and abundance of life forms which havelevolved with such an assemblage are very
important attributes of the "no project" environmental baseline with which all other alternatives
must be compared.
The environmental baseline provides benefits to water quality. Aside from the reduction of
waste water to the public treatment facilities, a restored barrier island will not be a source of non-
point runoff (e.g., lawn or household chemical runoff; polycyclic aromatic hydrocarbon runoff
from roads and driveways; deposition of volatized elements from internal combustion engines;
suspended sediments caused by construction runoff; and erosional scour associated with
bulkheads, boat channels, personal piers, and over-water gazebos). The restoration of a natural
inlet and overwash deltas should improve circulation and water quality in the vicinity of Mason's
Inlet; while some water quality criteria may not measurably improve, the restoration of the inlet
and island will be much more consistent with the objectives of the Clean Water Act -- to restore
and maintain the chemical, physical, and biological integrity of the Nation's waters -- of which
specific criteria are merely indicators. Furthermore, filtration of organic material and nutrients
by interstitial communities, including microbial mats, and micro- and meiofauna, should be more
efficient and the capacity increased as human influences on beach plan, profile, and sediment
grain size are reduced. We have not quantified the water quality benefits attributable to the
baseline environment, but in our opinion they are considerable.
The environmental baseline adds to the complexity and broad stability of the ecosystem by
reducing anthropogenic stressors on the diversity and integrity of habitats such as hardbottoms,
swash zones, and sandy bottoms. While it is unknown if the nearshore hardbottom and surf zone
habitats associated with Shell Island are obligate or facultative for this diverse array of fish
3
species that frequent hardbottom, nearshore and surf zone habitats, we anticipate that the
restoration of the system's natural pattern, dimension, profile, and ecosystem functions should
provide significant benefits in addition to the inlet and sound-side marsh habitat nursery
functions covered in the Report and FEIS.
Apparently, nearshore hardbottom habitat preferentially attracts and supports early life stages of
many fish species. Wrightsville Beach has significant areas of limestone hardbottoms just
offshore, as well as mud outcrops that can sometimes act very similarly to hardbottoms. These
hardbottoms are covered with only a thin veneer of modern sediments that averages 30
centimeters in thickness'. Hardbottom habitat in Florida, similar to that of Wrightsville Beach in
that it is composed of limestone, provides important nursery habitat for 34 species of fish', and
192 species of fish are recorded in association with nearshore hardbottom habitat.
Hardbottoms can provide very important habitat for fish and invertebrate species in North
Carolina. According to Burgess', "Some of these rocky hardbottoms are veritable oases covered
with algal meadows, sponges, soft whip corals, tropical fishes and territorial and predatory
animals. These habitats provide shelter and food to sustain valuable commercial and recreational
fish such as groupers and snappers, worth millions of dollars to the state's economy. More than
300 species of fish and hundreds of thousands of invertebrates call these reefs home."
The nearshore benthic environment supports a diverse ecological assemblage regardless of the
presence of hardbottoms. Van Dolah and Knott' sampled the benthos, including some
hardbottoms, offshore the South Carolina coast, and found 167 species representing nine major
taxa. McCrary and Taylor' studied benthic macrofauna assemblages approximately 0.5 to 2.0
miles offshore of Fort Fisher, North Carolina, and their grab samples included many polychaete
2Thieler, E. R., A. L. Brill, W. J. Cleary, C. H. Hobbs III, and R. A. Gammisch. 1995.
Geology of the Wrightsville Beach, North Carolina shoreface: Implications for the concept of
shoreface profile of equilibrium. Marine Geology 126:271-287.
'Lindeman, K. C. and D. B. Snyder. 1999. Nearshore hardbottom fishes of southeast
Florida and effects of habitat burial caused by dredging. Fish. Bull. 97:508-525.
'Burgess, C. B. 1993. A hard rock oasis under the sea. Coastwatch. North Carolina Sea
Grant Program. Raleigh, NC. March/April 2-7.
'Van Dolah, R.F. and D. M. Knott. 1984. A biological assessment of beach and
nearshore areas along the South Carolina Grand Strand. Marine Resources Division. South
Carolina Wildlife and Marine Resources Department, Charleston, SC.. 59p.. -
'McCrary, A.B. and A.Y. Taylor. 1986. Macroinfauna study - Fort Fisher, North
Carolina. Unpublished report. University of North Carolina at Wilmington, Wilmington, NC.
Submitted to the U.S. Army Corps of Engineers, Wilmington, NC. 25p.
4
species, isopods, amphipods, decapods, molluscs, echinoderms, many nematodes, and a few
Amphioxus (Brachiostoma caribaeum). Specifically, although hard substrate was not found in
the sediment samples of one of the closer sampling sites, they concluded it was obviously in the
vicinity because they found 33 individuals of Chrysopetidae, a family predominately associated
with coral or other hard substrates.
The surf zone itself is also a valuable habitat fora variety of fish and wildlife resources that
would be restored under the environmental baseline. Ross and Lancaster' found that juveniles of
at least two fish, the Florida pompano (Trachinotus carolinus) and Gulf kingfish (Menticirrhus
littoralis), exhibit strong fidelity to surf zone nursery habitat, and some surf zone fish appear to
feed on many invertebrates found in the substrate. Hackney et al.' state that "Apparently, many
surf zone fishes not only exhibit ontogenetic changes in diet, but also shift diets in relation to
prey availability... Such opportunism has great advantages in a variable environment like the
surf zone." The prey base thus becomes a vital part of the ecosystem and environmental baseline.
Invertebrate species appear to be very sensitive to the wave energy. Donoghue 9 found that the
coquina clam (Donax variabilis) and mole crab (Emerita talpoida), the two dominant swash zone
invertebrate species in North Carolina, prefer the downdrift horns of beach cusps; some of these
organisms "surf' the swash from cusp to cusp to move down the beach. The coquina were also
documented to move offshore in anticipation of a7 storm, and the prevailing theory is that the
clams sense a shift in the wave harmonics indicating an approaching storm system. The
abundance and dynamic stability of these beach invertebrates, and the birds and fishes that
depend upon them, would be restored and largely unperturbed by human activities under the
environmental baseline.
Both Donoghue' and Peterson' found that beach invertebrates were adversely impacted by beach
'Ross, S. W. and J. E. Lancaster. 1996. Movements of juvenile fishes using surf zone
nursery habitats and the relationship of movements to beach nourishment along a North
Carolina beach: Pilot project. National Oceanic and Atmospheric Administration Award No.
NA570Z0318. 31p.
'Hackney, C. T., M. H. Posey, S. W. Ross, and A. R. Norris (eds.). 1996. A review and
synthesis of data on surf zone fishes and invertebrates in the South Atlantic bight and the
potential impacts from beach nourishment. Prepared for the U.S. Army Corps of Engineers,
Wilmington District, Wilmington, NC. 111 p.
'Donoghue, C. R. 1999. The influence of swash processes on Donax variabilis and
Emerita talpoida Ph.D. dissertation; University of Virginia, Department of Environmental
Sciences. 197p.
9Peterson, C. H., D. H. M. Hickerson, and G. G. Johnson. In press. Short-term
consequences of nourishment and bulldozing on the dominant large invertebrates of the sandy
5
nourishment activities. In the former of the two studies, Donax sp. and Emerita sp. populations
took longer than the two to three year nourishment interval to fully recover. Numbers of
coquina and mole crabs were depressed by 86-99% on Bogue Banks one to two months
following nourishment in the latter study. These invertebrates serve as the prey base for many
other beach macrofauna, surf fishes, and shorebirds. The environmental baseline condition
would allow this vital coastal food web component to be restored to its historic level by
eliminating recurring nourishment and other construction activities on the beach, and by allowing
the natural beach plan, profile, and sediment grain size distribution to reassert itself.
The Northeast New Hanover Conservancy currently manages 88 acres of marsh and sand flat
habitat adjacent to Mason's Inlet. This conservation effort is a de facto acknowledgment of the
value of protecting even a portion of the fish and wildlife resources in the project impact area.
The environmental baseline, if associated with actions that place Shell Island in conservation
status as well, not only restores, enhances, and protects habitat used by Federally-listed sea
turtles, piping plover, and seabeach amaranth, but is an important step in meeting the Nation's
loggerhead turtle recovery objectives. Under the recovery plan, North Carolina's populations
will not require stringent protection when beaches which encompass 50% of the nesting activity
in the state have been placed in protected conservation status.
We appreciate the opportunity to comment on this matter. For the purpose of providing as
complete an administrative record as possible, we are providing the District Engineer with the
additional references cited in this report. They are being mailed under separate cover. If you
have any comments or questions, please contact Tracy Rice, David Rabon, or Kevin Moody of
this office at [phone] extensions 12, 16, or 19, respectively.
Sincerely,
??, we
Garland B. Pardue
Ecological Services Supervisor
attachments (2)
cc:
Applied Technology and Management, Inc., Wilmington, NC (Karyn Erickson)
Land Management Group, Inc., Wilmington, NC (Steve Morrison)
New Hanover County, NC (Greg Thompson)
NC DCM, Raleigh, NC (Doug Huggett)
beach. Journal of Coastal Research.
6
NC DCM, Wilmington, NC (Bob Stroud)
NC WRC, Marshallberg, NC (Ruth Boettcher)
NC DWQ, Raleigh, NC (John Dorney)
NMFS, Beaufort, NC (Larry Hardy)
EPA, Atlanta, GA (Thomas Welborn; Kathy Mathews)
FWS/R4:DRabon:DR:12/16/99:919/856-4520 extension 16:\lnewhan.wpd
t
7
United States Department of the Interior
FISH AND WILDLIFE SERVICE
Raleigh Field Office
Post Office Box 33726
Raleigh, North Carolina 27636-3726
December 20, 1999
Colonel James W. DeLony 41
District Engineer, Wilmington District
(SA
U.S. Army Corps of Engineers
Post Office Box 1890
Wilmington, North Carolina 28402-1890
Attention: Mr. Jeffrey Richter
Act
Dear Colonel DeLony:
Per our November 29, 1999 letter to you, the U.S. Fish and Wildlife Service (Service) is pleased
to provide the District Engineer with documents describing the "no project" environment related
to Action I.D. No. 199901052. The applicant, New Hanover County, proposes to stabilize
Mason's Inlet, mine sand, and nourish adjacent beaches by maintaining an artificially dredged
channel, installing a sand plug in the existing channel, and establishing sediment traps and
storage sites between Shell Island and Figure Eight Island north of Wrightsville Beach, New
Hanover County, North Carolina.
This document provides supplemental information submitted pursuant to, and in accordance
with, provisions of the Fish and Wildlife Coordination Act (48 Stat. 401, as amended; 16 U.S.C.
661 et seq.) and the Endangered Species Act of 1973 (87 Stat. 884, as amended; 16 U.S.C. 1531
et seq.).
The Environmental Analysis (EA) submitted in conjunction with the application significantly
misstated the reasonably foreseeable environment without the project. As implied in the
proposal's purpose and need, the current environment is transitional. If no project is authorized,
according to the applicant, Mason's Inlet will continue migrating to some point between the
current location and Moore's Inlet. The structures and infrastructure in the path of the migrating
inlet will be relocated or otherwise removed at the expense of the county and private property
owners. The "no project" baseline from which all other alternatives must be evaluated is that of
a restored barrier island with all human structures and infrastructure removed, and with partial
restoration of the integrity of the soundside marshes and ecosystem (i.e., in addition to the
restoration of the barrier islands' undisturbed form and structure, natural processes would be
largely unimpeded). Thus, the future "no project" environment is a restored barrier island,
unstabilized inlet, and partially restored sound.
To describe this future environment, we are attaching two reports: (1) the Service's 1981 Final
Fish and Wildlife Coordination Act Report (Report), written prior to the development of this
portion of Shell Island; and, (2) selections from the Department of Commerce's and North
Carolina Department of Natural Resources and Community Development's (now Department of
Environment and Natural Resources, Division of Coastal Management) 1984 Final
Environmental Impact Statement and Draft Management Plan for the Proposed Masonboro
Island Component of the North Carolina National Estuarine Sanctuary (FEIS). We include the
Masonboro Island report because it describes a nearby undeveloped barrier island adjacent to
Wrightsville Beach. However, the jetties at Masonboro Inlet, maintenance and expansion of the
authorized channels, beach nourishment of Wrightsville Beach, and mismanaged sediment
bypassing scheme mean that Masonboro Island's ecosystem must be considered degraded. While
the FEIS describes an undeveloped barrier island, reviewers should bear in mind that the FEIS is
describing an ecosystem which has less functional and structural integrity than the system which
is reasonably foreseeable on Shell Island under the "no project" alternative. Further, scientific
advances have been made in the 20 years since the Report and FEIS were prepared. Additional
references are available and barrier island/sound ecosystems in general can supplement the two
documents. We believe the combination of the Report (pages 2-6; and 9-22; and the attached
Planning Aid Report), FEIS (pp. 54-67; and appendices 5,6, 7, and 8 [pp 293-330]), and
literature synthesis provided below establish a reasonable information base for evaluating the
environmental impacts of the proposal.
In our opinion, the "no project" alternative provides significant benefits to fish and wildlife
resources, federal trust species, water quality, and the human and economic environment. The
"no project" alternative will restore the ecological integrity of aquatic resources of national
importance and could partially fulfill loggerhead sea turtle recovery objectives in North
Carolina'.
We note that the FEIS states that "Masonboro Island is the best example for its typology in the
state of North Carolina" (pp. 45). The significance of the reasonably foreseeable future
environment under the "no project" alternative is nowhere more clear than in that statement.
Natural processes are impeded on Masonboro Island by sand mining, jetties, inadequate sand
bypass schemes, and maintenance of navigation channels. We can only speculate on the
improved example the restored Shell Island ecosystem and partially restored sound could
provide. The environmental baseline will enhance educational and research opportunities for
local educational facilities, as well as provide additional study areas for birdwatching and other
recreational pursuits (see especially FEIS, pp. 127-131). Based on the available information, we
believe the New Hanover County Board of Commissioners will recognize that the "no project"
alternative provide opportunities which they have unanimously endorsed in the past. As recorded
'National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1991. Recovery
Plan for U.S. Population of Loggerhead Turtle. National Marine Fisheries Service, Washington,
D.C.
2
in the FEIS (pp. 109-110), the Commissioners supported efforts to keep Masonboro Island
undeveloped and "pristine" because of it's "unique" and "significant value" in educational,
economic, recreational, and scientific terms. They recognized that the provision of "public
services on undeveloped barrier islands would ... be prohibitively expensive when compared with
service costs in other areas of the county;" and the unsuitablitiy of barrier islands like Shell
Island for development ("Masonboro Island is dynamically unstable due to inlet migration and
long-term erosion, which would endanger the establishment of permanent communities").
We stress that through the 'imaginative use of mitigation banks, tax credits, and hazard mitigation
grants, the "no project" alternative need not adversely affect the current property owners of the
affected area. If designed to allow current owners the use of existing structures until death or
erosion limits the habitability of the structures, and if payments are made at currently assessed
values, the environmentally preferable "no project" alternative would be realized with little or no
social dislocation. The "no project" alternative is consistent with Executive Orders 11988
Floodplain Management and 11990 Protection of Wetlands.
The environmental baseline provides additional benefits to fish and invertebrates not described in
the Report and FEIS. These include unquantified improvements in water filtration efficiency and
the diversity and integrity of habitats. The restoration of diverse habitats, linkages, and the
diversity and abundance of life forms which have evolved with such an assemblage are very
important attributes of the "no project" environmental baseline with which all other alternatives
must be compared.
The environmental baseline provides benefits to water quality. Aside from the reduction of
waste water to the public treatment facilities, a restored barrier island will not be a source of non-
point runoff (e.g., lawn or household chemical runoff; polycyclic aromatic hydrocarbon runoff
from roads and driveways; deposition of volatized elements from internal combustion engines;
suspended sediments caused by construction runoff; and erosional scour associated with
bulkheads, boat channels, personal piers, and over-water gazebos). The restoration of a natural
inlet and overwash deltas should improve circulation and water quality in the vicinity of Mason's
Inlet; while some water quality criteria may not measurably improve, the restoration of the inlet
and island will be much more consistent with the objectives of the Clean Water Act -- to restore
and maintain the chemical, physical, and biological integrity of the Nation's waters -- of which
specific criteria are merely indicators. Furthermore, filtration of organic material and nutrients
by interstitial communities, including microbial mats, and micro- and meiofauna, should be more
efficient and the capacity increased as human influences on beach plan, profile, and sediment
grain size are reduced. We have not quantified the water quality benefits attributable to the
baseline environment, but in our opinion they are considerable.
The environmental baseline adds to the complexity and broad stability of the ecosystem by
reducing anthropogenic stressors on the diversity and integrity of habitats such as hardbottoms,
swash zones, and sandy bottoms. While it is unknown if the nearshore hardbottom and surf zone
habitats associated with Shell Island are obligate or facultative for this diverse array of fish
species that frequent hardbottom, nearshore and surf zone habitats, we anticipate that the
restoration of the system's natural pattern, dimension, profile, and ecosystem functions should
provide significant benefits in addition to the inlet and sound-side marsh habitat nursery
functions covered in the Report and FEIS.
Apparently, nearshore hardbottom habitat preferentially attracts and supports early life stages of
many fish species. Wrightsville Beach has significant areas.of limestone hardbottoms just
offshore, as well as mud outcrops that can sometimes act very similarly to hardbottoms. These
hardbottoms are covered with only a thin veneer of modern sediments that averages 30
centimeters in thickness'. Hardbottom habitat in Florida, similar to that of Wrightsville Beach in
that it is composed of limestone, provides important nursery habitat for 34 species of fish', and
192 species of fish are recorded in association with nearshore hardbottom habitat.
Hardbottoms can provide very important habitat for fish and invertebrate species in North
Carolina. According to Burgess4, "Some of these rocky hardbottoms are veritable oases covered
with algal meadows, sponges, soft whip corals, tropical fishes and territorial and predatory
animals. These habitats provide shelter and food to sustain valuable commercial and recreational
fish such as groupers and snappers, worth millions of dollars to the state's economy. More than
300 species of fish and hundreds of thousands of invertebrates call these reefs home."
The nearshore benthic environment supports a diverse ecological assemblage regardless of the
presence of hardbottoms. Van Dolah and Knott' sampled the benthos, including some
hardbottoms, offshore the South Carolina coast, and found 167 species representing nine major
taxa. McCrary and Taylor' studied benthic macrofauna assemblages approximately 0.5 to 2.0
miles offshore of Fort Fisher, North Carolina, and their grab samples included many polychaete
2Thieler, E. R., A. L. Brill, W. J. Cleary, C. H. Hobbs III, and R. A. Gammisch. 1995.
Geology of the Wrightsville Beach, North Carolina shoreface: Implications for the concept of
shoreface profile of equilibrium. Marine Geology 126:271-287.
'Lindeman, K. C. and D. B. Snyder. 1999. Nearshore hardbottom fishes of southeast
Florida and effects of habitat burial caused by dredging. Fish. Bull. 97:508-525.
'Burgess, C. B. 1993. A hard rock oasis under the sea. Coastwatch. North Carolina Sea
Grant Program. Raleigh, NC. March/April 2-7.
'Van Dolah, R.F. and D. M. Knott. 1984. A biological assessment of beach and
nearshore areas along the South Carolina Grand Strand. Marine Resources Division. South
Carolina Wildlife and Marine Resources Department, Charleston, SC. 59p.
'McCrary, A.B. and A.Y. Taylor. 1986. Macroinfauna study - Fort Fisher, North
Carolina. Unpublished report. University of North Carolina at Wilmington, Wilmington, NC.
Submitted to the U.S. Army Corps of Engineers, Wilmington, NC. 25p.
4
species, isopods, amphipods, decapods, molluscs, echinoderms, many nematodes, and a few
Amphioxus (Brachiostoma caribaeum). Specifically, although hard substrate was not found in
the sediment samples of one of the closer sampling sites, they concluded it was obviously in the
vicinity because they found 33 individuals of Chrysopetidae, a family predominately associated
with coral or other hard substrates.
The surf zone itself is also a valuable habitat for a variety of fish and wildlife resources that
would be restored under the environmental baseline. Ross and Lancaster' found that juveniles of
at least two fish, the Florida pompano (Trachinotus carolinus) and Gulf kingfish (Menticirrhus
littoralis), exhibit strong fidelity to surf zone nursery habitat, and some surf zone fish appear to
feed on many invertebrates found in the substrate. Hackney et al.' state that "Apparently, many
surf zone fishes not only exhibit ontogenetic changes in diet, but also shift diets in relation to
prey availability... Such opportunism has great advantages in a variable environment like the
surf zone." The prey base thus becomes a vital part of the ecosystem and environmental baseline.
Invertebrate species appear to be very sensitive to the wave energy. Donoghue' found that the
coquina clam (Donax variabilis) and mole crab (Emerita talpoida), the two dominant swash zone
invertebrate species in North Carolina, prefer the downdrift horns of beach cusps; some of these
organisms "surf"the swash from cusp to cusp to move down the beach. The coquina were also
documented to move offshore in anticipation of a• storm, and the prevailing theory is that the
clams sense a shift in the wave harmonics indicating an approaching storm system. The
abundance and dynamic stability of these beach invertebrates, and the birds and fishes that
depend upon them, would be restored and largely unperturbed by human activities under the
environmental baseline.
Both Donoghue' and Peterson' found that beach invertebrates were adversely impacted by beach
'Ross, S. W. and J. E. Lancaster. 1996. Movements of juvenile fishes using surf zone
nursery habitats and the relationship of movements to beach nourishment along a North
Carolina beach: Pilot project. National Oceanic and Atmospheric Administration Award No.
NA570Z03.18. 31p.
'Hackney, C. T., M. H. Posey, S. W. Ross, and A. R. Norris (eds.). 1996. A review and
synthesis of data on surf zone fishes and invertebrates in the South Atlantic bight and the
potential impacts from beach nourishment. Prepared for the U.S. Army Corps of Engineers,
Wilmington District, Wilmington, NC. 1 I Ip.
'Donoghue, C. R. 1999. The influence of swash processes on Donax variabilis and
Emerita talpoida Ph.D. dissertation; University of Virginia, Department of Environmental
Sciences. 197p.
'Peterson, C. H., D. H. M. Hickerson, and G. G. Johnson. In press. Short-term
consequences of nourishment and bulldozing on the dominant large invertebrates of the sandy
5
nourishment activities. In the former of the two studies, Donax sp. and Emerita sp. populations
took longer than the two to three year nourishment interval to fully recover. Numbers of
coquina and mole crabs were depressed by 86-99% on. Bogue Banks one to two months
following nourishment in the latter study. These invertebrates serve as the prey base for many
other beach macrofauna, surf fishes, and shorebirds. The environmental baseline condition
would allow this vital coastal food web component to be restored to its historic level by
eliminating recurring nourishment and other construction activities on the beach, and by allowing
the natural beach plan, profile, and sediment grain size distribution to reassert itself.
The Northeast New Hanover Conservancy currently manages 88 acres of marsh and sand flat
habitat adjacent to Mason's Inlet. This conservation effort is a de facto acknowledgment of the
value of protecting even a portion of the fish and wildlife resources in the project impact area.
The environmental baseline, if associated with actions that place Shell Island in conservation
status as well, not only restores, enhances, and protects habitat used by Federally-listed sea
turtles, piping plover, and seabeach amaranth, but is an important step in meeting the Nation's
loggerhead turtle recovery objectives. Under the recovery plan, North Carolina's populations
will not require stringent protection when beaches which encompass 50% of the nesting activity
in the state have been placed in protected conservation status.
We appreciate the opportunity to comment on this matter. For the purpose of providing as
complete an administrative record as possible, we are providing the District Engineer with the
additional references cited in this report. They are being mailed under separate cover. If you
have any comments or questions, please contact Tracy Rice, David Rabon, or Kevin Moody of
this office at [phone] extensions 12, 16, or 19, respectively.
Sincerely,
Garland B. Pardue
Ecological Services Supervisor
attachments (2)
cc:
Applied Technology and Management, Inc., Wilmington, NC (Karyn Erickson)
Land Management Group, Inc., Wilmington, NC (Steve Morrison)
New Hanover County, NC (Greg Thompson)
NC DCM, Raleigh, NC (Doug Huggett)
beach. Journal of Coastal Research.
6
NC DCM, Wilmington, NC (Bob Stroud)
NC WRC, Marshallberg, NC (Ruth Boettcher)
NC DWQ, Raleigh, NC (John Dorney)
NMFS, Beaufort, NC (Larry Hardy)
EPA, Atlanta, GA (Thomas Welborn; Kathy Mathews)
FWS/R4:DRabon:DR:12/16/99:919/856-4520 extension 16:\lnewhan.wpd
7
DIVISION OF COASTAL MANAGFAMiT
FIELD INVESTIGATION REPORT
1. APPLICANT'S NAME: New Hanover County
.2. LOCATION OF PROJECT SITE: Mason Inlet, between Figure 8 Island and Wrightsville,
Beach, in New Hanover Co.
Photo Index -124$: 11-224 & 22619.9.1:24-2911M:5 176-21 & 22 19-BA: 19-283 & 284
State Plane Coordinates - X:2371651 Y:182526
3. INVESTIGATION TYPE: CAMA/D&F
4• INVESTIGATIVE PROCEDURE: Dates of Site Visit - 7//29/99, 10/7/99, 10/28/99
Was Applicant Present - Yes (Applicant or agent)
5. PROCESSING PROCEDURE: Application Received - 11/1/99 (EA rec. in Raleigh)
Office - Wilmington
6. SITE DESCRIPTION:
(A) Local land Use Plan - New Hanover. Co.
Land Classification From LUP - Conservation
(B) AEC(s) Involved: EW,PT,OH,CW
(C) Water Dependent: Yes
(D) Intended Use: Public/Private
(E) Wastewater Treatment: Ei j?ta - N/A .
Planned None
(F) Type of Structures: Existing - None
Planned - None (Inlet relocation project)
(G) Estimated Annual Rate of Erosion: N/A
Source - N/A
7. HABITAT DESCRIPTION: [AREA]
DREDGED 1ILLED
(A) Vegetated Wetlands 126,324 sgft.
(2.9 acres)
(S) Non-Vegetated Wetlands 2,134,?? 1.800.Onn
Open water ft. (49 acn.
ft_ (4l acrecl
(C) Other - Beach Renourishment 2,550,000 sq.
(D) Total Area Disturbed: 154.3 acres ft (58.5 acres)
(E) Primary Nursery Area: No
(F) Water Classification: SA-ORW Open: CLOSED
8. PROJECT SUMMARY: The applicants propose to relocate Mason Inlet 3,000 to the north of
it
New Hanover Co./Mason Inlet Relocation Project
Page 2
its present location and to dredge the shoaled Mason Creek to provide a sufficient tidal prism to maintain
locational stability of the new inlet channel.
9. PROJECT DESCRIMON
Mason Inlet is located between Wrightsville Beach (south) and Figure 8 Island (north), in New Hanover
County. The inlet provides one of the connections to the Atlantic Ocean for Middle Sound, which
includes an approximately 13 mile long estuary between the beaches and the mainland, between
Masonboro Inlet (south) and Little Topsail Inlet (north). Rich Inlet provides a fourth ocean outlet for
Middle Sound. Middle Sound encompasses broad expanses of Smooth Cordgrass (Spartina altem flora)
marsh, tidal flats, and creeks, between the barrier islands and the mainland, including the following major
tidal creeks: Howe; Pages, Futch, Mason, Banks Channel (behind south Figure. 8 Island), Nixon and
Green Channels, as well as, the Atlantic Intracoastal Waterway, between Wrightsville and Topsail
beaches. The project area involves an approximately 90 acre area of Mason Inlet and Mason Creek.
Over the past five decades, Mason Inlet has migrated approximately 6,500 feet south to it's present
location. Since 1980 the inlet throat has moved approximately 3500 feet to the south, and currently
presents an erosion threat to the development on the northern end of Wrightsville Beach, including the
multi-story Shell Island Resort complex, the terminus of North Lumina Avenue, as well as numerous
single-family and multi-family residential structures located to the south of the resort. A public beach
accessway, bath house, parking lot, as well as, the northern terminus of North Lumina Avenue have
already been lost to erosion. In 1997, authorization was obtained by the Shell Island Homeowners
Association to install a temporary sand-filled geotextile tube revetment along the north and a portion of
the east sides of the Shell Island Resort complex. The Town of Wrightsville Beach also obtained
emergency permits to install conventional sandbags to temporarily protect the end of North Lumina
Avenue. The throat of Mason Inlet is currently located at the base of these temporary structures.
llistorically, Mason Creek was one of the two primary channels between Mason Inlet and the AIWW.
Mason Creek _Provides an east-west channel orientation to the inlet and the north-south orientation of
Banks Channel, behind Figure 8 Island, is the inlet's other primary channel. Extensive shoaling along the
entire length (approx. 4,500 ft.) of Mason Creek has significantly reduced it's contribution to the
hydraulic volume of the inlet. Once over 400 feet wide
the open water area of the creek has been
narrowed in some areas to less than 100 feet in width, due to shoal accretion and subsequent emergent
stands of Smooth Cordgrass (Spart;na.alterniflora) vegetation. At low water, the creek is not navigable,
however, with local knowledge of the narrowed channel, the creek is passable at mid to high water in
small, shallow draft watercraft. In contrast, the channelization of Banks Channel in the 1960s, b the
early developers of Figure 8 Island, and the continued maintenance of that navigation channel to the
present, by the Figure 8 Island Property Owners Association (State Permit # 26-92) have kept the 13,570
ft. long, 125 ft. wide channel open to a depth of -9 feet, at mean low water. Excavated sediments from
the maintenance dredging projects are utilized to =nourish the chronically eroded beach front of the
southern half of Figure 8 Island. At present, Banks Channel is the primary hydrologic component of the
tidal exchange for Mason Inlet.

New Hanover Co./Mason Inlet Relocation Project
Page 3
In the project area., the waters of Mason Creek are classified as SA-ORW, by the NC Division of Water
Quality, and they are OPEN to the harvest of shellfish. Although the saltmarsh on either side of the
project area are designated as Primary Nursery Area (pNA), by the NC Division of Marine Fisheries,
the waters of Mason Inlet and Mason Creek are not included in the surrounding PNA designation.
The applicants propose to relocate Mason Inlet 3,000 to the north of its present location and to dredge
the shoaled Mason Creek to provide a sufficient tidal prism to maintain locational stability of the new inlet
channel. The concept of the relocation of Mason Inlet began in the fall of 1996, as a joint venture of the
Shell Island Resort Homeowners Association and the Figure 8 Beach Homeowners Association, to address
the erosion problems of Shell Island Resort and the beach renourishment needs of Figure 8 Island. A draft
Environmental Assessment was prepared for preliminary review in connection with the proposed project,
however, when the project sponsors were unable to obtain the necessary rights from the
to allow the inlet relocation, plans to submit a P property owners
permit application were suspended. Direct hits from five
(5) major hurricanes over the last four years have exacerbated the erosion threat to both Figure 8 Island
and the north end of Wrightsville Beach. The current application is submitted with New Hanover Coun
as the project's sponsor. Their legal agreement with the propefty owners to allow the ?'
in this application. F baure 8 Beach Homeowers Association and Shell Island Resort Homeowners
Association, as well as, other property owners that would benefit from -the inlet relocation, remain as
active parties in the project. Benefiting property owners will repay the County's loan that would provide
funding for the project, and Figure 8 Beach HOA would purchase excavated sediments for beach
renourishment. An Environmental Assesment (EA) for the project has been prepared by Applied
Technology and Management of North Carolina, Inc. and Land
Management Group, Inc. and is being
reviewed concurrently with this application by State and federal agencies through the Clearing House
review process, as required by the State Environmental Policy Act. Detailed information with respect to
the proposed project's purpose, existing environment, need for action, alternatives analysis, environmental
consequences, and mitigative measures are presented in this document, as well as, the hydrodynamic
modeling data used to design the project's proposed dimensions. The EA's prefered alternative is the
proposed project in this application.
The proposed -new inlet channel would be dredged through the southern end of Figure 8 Island, within
the inlet corridor, approximately 3,000 feet north of its present location. The inlet channel would be 2100
feet long, 500 feet wide, and excavated to a depth of -10 feet {NGVD(NLW is Mason Creek channel would be dredged from the A1WW to the relocated inlet channel. NGVD)}. The
would be 3400 feet long and 170 feet wide, excavated to a depth of -8 feet GVD This channel
basin would be excavated adjacent to the new inlet channel, on the inside of the inlet throat. Them onon
of the basin would be located south of the dredged channel and would function to capture and retain sand
flows and reduce shoaling effects in Mason Creek. The basin's combined area would be approximately
1000 feet long and average 500 feet in width. It would be excavated to the same depth as the inlet
channel, -10 feet (NGVD). The project would begin with the dredging of Mason ereek, ex
material would be stockpiled, above MHW, at the south end of Figure 8 Island and the north endtof
Wrightsville Beach. The work would Proceed, east to west, into the areas of the sedimentation basin and
and the new inlet channel, leaving a plug at the west end
(AFWR) of Mason Creek and an ocean plug at
, ?
New Hanover CoJAWon Inlet Relocation Project
Page 4
the east end of the inlet channel
would be . Dredging from the near shore ocean bottom, -6 to -12 foot contour,
utilized to during the initial opening of the inlet- These excavated materials would be u
onto the beach at Figure 8 Island. The proposed beach renourishment profile provides for the placement
of 35 to 50 cubic yards of sand per linear foot
least 1,500 feet north of the new of shoreline. Deposition of the material would begin at
inlet's position and continue north for approximately 8,500 feet. The
resulting beach profile, after reaching equilibrium, is expected to produce an additional 70
width to the upper beach with an elevation increase of 6 feet, that will transition to an ele ationore0 foot
of 2 feet in the near shore surf zone, on the east side-of the approximately 300 feet wide impacted r eae
Closure of the the existing inlet and construction of the southern fill area would be completed utilizing
a rapid mechcanical sand moving operation upon successful opening of the new inlet. The resulting fill
area at the north end of Wrightsville Beach would be approximately 1, 800 feet long and 1,000 feet wide
at its base. The submitted project drawings show the top width of the fill area to be 400 feet wide
constructed to an elevation of +10 feet (NGVD).
10. ANTICIPATED IlVIPACTS
The excavation of the Mason Creek channel would incorporate 126,324
(2-9 acres) Of th
Cordgrass (Spanina ahem flora) marsh. The square
an east applicant's EA states that this impact t is necessary t osrestore
-west dominant flo w to the inlet mouth for stab' '
'- The applicant proposes to mitigate
by replanting a 5.8 acre hurricane overwash fan with sparlina alrerni, flora, to restore the h or this loss
is located in the southwest corner of the project area. The proposed project's total excavation This tract
area
including Mason Creek, the new inlet channel, and the sedimentation basin, would
square feet (49 acres) of sandy, shallow bottom. The 2, 134,
proposed beach renourishment area of disturb the e souther 440
end Figure 8 Island has been Pn
Previously permitted in conjunction with State Permit # 26-92. The
deposition of this material would disturb 2,550,000 square feet (58.5 acres) of
zone along the southern half of the Figure 8 Island oceanfront. And, the ' upper beach and inter-tidal
southern fill area would incorporate 1,800,000 square feet (41 acres) of open wa eOf the- existing inlet rr and intertidal area.
Conversely, the relocated inlet would create 1,050,000 square feet (24 acres) of new open water/intertidal
area.
The applicant's EA states that a number of positive impacts would result from the project including:
enhanced nutrient exchange and productivity, as well as, improved water
quality resulting from the
restoration of flows to Mason Creek. Also, there would be positive effects on recreational navigation and
public access to the inlet area. Their study also concedes that this proposal is not a permanent _
to the southerly migration of Mason Inlet. The inlet channel and sedimentation basin would lneed
maintenance on approximately a five (5) year cycle, as well as, the maintenance of Mason Crete
as needed basis. Thus, all of the direct impacts of the project would be x
epe ebi A , occurk on an
Presumably indefinitely. The proposed project would provide a privately funded approach t address rence,
beach erosion problems of Figure 8 Island and inlet mig e
ration threat to the north end of the
Beach, without the use of State or federal public monies. Wrightsvill
Submitted by: E.F. Brooks Date: 12/20/99 Office: Wilmington
APPENDIX "A"
NEW HANO'VER COUNTY
ENGINEERING DEPARTMENT
414 CHESTNUT STREET
WILMINGTON, NORTH CAROLINA 284014045
7ELE.PHONE [phone]
WYATr L R1ANC9ARD, P:&
Couaty Emgizteer
August 2, 1999
Karyn M. Erickson, Vice President
Applied Technology and Management of
North Carolina, Inc.
201 North Front Street - Suite 201
Wilmington, North-Carolina 28401
RE: Ackn-Owle-dgment and Authorization
Mason's Inlet Project
Dear Ms. Erickson-
New Hanover County authorizes Applied Technology and Management of
North Carolina, Incorporated to act on -its behalf for the specific and limited purpose
of Notice Agent. The Federal and North Carolina State governments and their
entitles are hereby authorized to deliver responses, notifications, or other documents
to said Applied Technology and Management of North Carolina, Inc. in lieu of direct
service on the principal, Yew Hanover County. This Acknowledgment and
,(authorization does not in any way create, delegate, sanction, or permit any decision
maldng power or undertaking by Applied 'T'echnology and Management of North
-Carohrlaa, Inc:. on behalz of New Hanover County.
Best regards,
2,",
,:"4 Gregory R. Thompson, P.E_
Chief Project Engineer
New Hanover County
cc: Kemp Burpeau, Deputy County Attorney
GRT/aj
(? i 7
! v?
SEP G 2 19,919
COAST) ??eT
STATE OF NORTH CAROLINA
COUNTY OF NEW HANOVER
AGREEMENT FOR Pt7RCgASE OF
INTERESTS IN REAL, PROPERTY
THIS AGREEMENT FOR PURCHASE OF INTERESTS IN REAL PROPERTY
(Agreement) made as of ??`,? Z? 1999 by and between the
George Henry Hutaff Trust No. 2 by OLIVER C. HUTAFF, JR. and TABITHA
H. McEACHERN, Trustees (Seller) and FIGURE 118" BEACH HOMEOWNERS
ASSOCIATION, INC., a North Carolina non-profit corporation (Buyer).
RECITALS:
WHEREAS, Seller is owner of an undeveloped upland tract of
land located at the southern end of Figure Eight Island in New
Hanover County, North Carolina which is bounded on the east by the
waters of the Atlantic Ocean, on the west by the waters of Mason
Channel, on the north by lots and common area of Figure Eight Island
and on the south by the waters of Mason Inlet; and
WHEREAS, the Buyer and others are undertaking a project to
relocate Mason Inlet to a more northerly location in an effort to
improve the navigation.of Mason Creek from the Atlantic Intracoastal
Waterway to the relocated inlet and into the Atlantic Ocean; and to
use the sand from the related dredging activities to close the
existing channel of Mason Inlet and rebuild the ocean beaches at
Figure Eight Island (the Project); and
WHEREAS, the Seller is willing to convey the property
rights described in this Agreement to allow the Project to be
undertaken, provided the terms and conditions of this Agreement are
met ; and
I a r
177" 7
D!2`hSk _
IS TAL
WHEREAS, the County of New Hanover has been approached by
Buyer and others to be a sponsor of this Project and to exercise the
power of eminent domain to acquire the necessary property rights from
Seller if a voluntary sale cannot be accomplished; and
WHEREAS, for purposes of this Agreement, the Seller's-
property is divided into three tracts of land in which-different
property rights are to be conveyed, which tracts and the interest to
be conveyed as to each are described generally as follows:
(a) Inlet Corridor. A 1,000-foot wide corridor extending
from the high water mark of the Atlantic ocean to the
high water mark of Mason Channel (aka Banks Channel)
between parallel lines that are approximately
perpendicular to the ocean shoreline with the northern
parallel line beginning at the high watermark of the
Atlantic Ocean 200 feet south of the southernmost
point in the southern boundary of the southernmost lot
at Figure Eight (Inlet Corridor). This property is to
be conveyed in fee simple without warranty and with
conditions and right of re-entry.
(b) Temporary Construction Easement South Tract. A
temporary construction easement over all of.the upland
property lying south of the southern line of-'the Inlet
Corridor and north of the high water mark of Mason
J Inlet at the time of grant (South Tract) together with
cam, - , an option to secure future
temporary
construction

_ easements for future inlet maintenance projects as
described in this Agreement.
7Z

?
0
0
2
;
(c) Permanent Construction Easement North Tract Ocean
Shoreline. A permanent construction easement along
the ocean shoreline for that portion of Seller's
property remaining north of the Inlet Corridor for
purposes of Project construction and maintenance and
for pipeline placement for future beach Aourishment
projects on Figure Eight Island subject to conditions;
and
WHEREAS, the parties have agreed to various terms and
conditions regarding this sale, all of which are consideration for
the agreement between the parties as contained in this Agreement.
NOW, THEREFORE, in consideration of the funds, covenants
and agreements herein contained, the receipt and sufficiency of which
are hereby acknowledged, the parties agree as follows:
1. Incorporation of °Whereas" clauses. The "Whereas"
clauses set forth above in this Agreement are incorporated in this
Agreement by reference.
2. Sale of Inlet Corridor. Seller agrees to sell and
Buyer or its assigns agrees to buy the Inlet Corridor as described in
Exhibit "A" attached hereto and incorporated herein by reference,
subject to the terms and conditions of this Agreement. The
conveyance will be by non-warranty deed in the form and substance of
Exhibit "B" attached hereto and incorporated herein by reference..
3. Conveyance of Temporary Construction Easement for
South Tract. Seller agrees to convey to New Hanover,.County-, 16r-ot-h-6i,,
entity acceptable to Buyer and Seller, a temporary construction!
easement over all of Seller's property now located on the south end
of Figure Eight Island that lies south of the Inlet Corridor. The
description of the area covered by the easement is set out in Exhibit
"C" attached hereto and incorporated herein by reference. The value
of the easement is $55,000.00 per calendar year or part thereof and
the easement will expire twenty-four (24) months after ttfe easement
or a memorandum of the easement is recorded in the New Hanover County
Registry by Buyer or Seller except as specified in Exhibit "D". The
current Temporary Construction Easement or a memorandum thereof shall
be recorded by Buyer when this transaction is closed. The Temporary
Construction Easement will be in the form and substance of Exhibit
"D" which is attached hereto and incorporated herein by reference.
4. Option for Future Temporary Construction Easements.
Seller agrees to convey to Buyer or its assigns an option to acquire
annual construction easements over the South Tract in the future for
purposes of reconstruction or maintenance of the Project. The option
will extend for 30 years and will be in the form and substance of
Exhibit "D" which is attached hereto and incorporated herein by
reference.
5. South Tract Access and Claims to Filled Areas. In the
event the current inlet channel is filled in connection with the
project thereby connecting Seller's South Tract to Wrightsville
Beach, Buyer and its assigns will support Seller's request for -a 60-
foot wide non-exclusive access easement connecting'the South Tract to
the public streets of Wrightsville Beach and will actively assist
Seller in its efforts 'to acquire such an easement. In addition, if
Buyer, its successors or assigns proposes to engage in a maintenance
4
Project or any other dredging or filling. project which involves
raising land that was within the boundaries of the South Tract at the
time of the closing but which has become submerged since the time of
closing due to erosion or avulsion, Buyer will allow Seller to be a
co-applicant for required governmental permits and will recognize
Seller, its successors or assigns, as the appropriate `person or
entity to make any claims to title to land raised within the former
boundaries of the South Tract under the provisions of Chapter 146 of
the North Carolina General Statutes.
6. Permanent Construction Easement on Oceanfront North of
Inlet Corridor. Seller agrees to convey to Buyer a permanent non-
exclusive easement over and across the oceanfront portion of Seller's
property lying immediately north of the Inlet Corridor and extending
from the high water mark of the Atlantic Ocean 75 feet landward. The
easement is for the purposes set out in Exhibit '?E". The - easement
will be in the form and substance of Exhibit "E" which is attached
hereto and incorporated herein by reference.
7. Purchase Price. The purchase price for the Inlet
Corridor and the permanent construction easement north of the Inlet
Corridor is $340,000.00. The temporary construction easement over
the property south of the Inlet Corridor is valued at $55,000.00 per
calendar year or part thereof and will be donated by the Seller to
New Hanover County or other entity acceptable to.Buyer and Seller for
the initial 24 month period. Seller shall not unreasonably withhold
acceptance of an entity selected by Buyer. The purchase price will
be paid by a $ 40,000.00 non-refundable (except on failure of Seller
5
to perform) payment to be made upon the execution of this Agreement,
and the $300,000.00 balance will be paid in cash at closing. In
addition, the Grantee of the Temporary Construction Easement shall
pay the total ad valorem taxes assessed against the easement property
and/or on any taxable property related to the Temporary Construction
Easement for each calendar year, including the year in which the
closing occurs, during which the easement is either available or in
effect for all or part of the year.
8. Inlet Corridor Boundaries Fixed. The deed of
conveyance of the Inlet Corridor will be in the form and substance of
Exhibit "B" attached hereto and incorporated herein by reference.
Within two weeks of the execution of this Agreement, the Inlet
Corridor will be surveyed and mapped at the expense of the Buyer
using the description in Exhibit "A The northern and southern
parallel boundaries of the Inlet Corridor will be fixed as of the
date of the survey and the parties' respective rights to accreted
land or losses of land due to erosion will be governed by extending
or shortening the parallel lines to account for fluctuations in the
high water mark. Within two weeks prior to the closing, the entire
property (all three tracts) will be surveyed at the expense of Buyer.
The northern and southern boundaries of the Inlet Corridor will
remain as specified above and all of the instruments of conveyance
will reference the high water mark at the time of the second survey.
Upon approval by the parties, a map of the current survey will be
recorded in the New Hanover County Register of Deeds by the Buyer at
the time of closing. The boundaries for the Inlet Corridor shall
remain fixed regardless of erosion or accretion in accordance with
6
the terms of Exhibit "B however, if the inlet migrates outside of
the Inlet Corridor, the Seller shall be entitled to re-enter the
property in accordance with the terms of Exhibit "B".
9. Reaffirmation of Seller's Easement and Development
.Rights on Figure Eight Island. Buyer will reaffirm and more clearly
specify Seller's rights of access across the bridge and roads serving
as access to and over Figure Eight Island to Seller's property, and
Seller will acknowledge its obligations to the Figure "8" Beach
Homeowners Association in the form and substance contained in Exhibit
"F" attached hereto and incorporated herein by reference. This
provision of this Agreement will remain the obligation of Figure "8"
Beach Homeowners Association, Inc regardless of its assignment of
this Agreement to another party, or failure of-it or its assignee to
perform and shall be done and made effective at the time of the
execution of this Agreement.
10. Conditions to be Met Prior to Closing.
(a)

The membership of the Buyer must approve any
special assessment required to be approved by the
membership for the closing of the transaction.
This approval, if required, will be submitted for
a vote by the membership within one hundred
eighty (180) days of the date that New Hanover
County declines to sponsor the Project. If New
Hanover County agrees to- sponsor the Project,
this condition shall be deemed met.
7
(b) Approval by New Hanover County, or some other
entity acceptable to Seller, to serve as grantee
of the temporary construction easement valued as
indicated hereinabove. Buyer must immediately
undertake and use its best efforts to accomplish
acquiring an acceptable grantee within one
hundred eighty (180) days of the date that New
Hanover County declines to be the grantee.
(c) The acquisition by Buyer, or by any other entity
undertaking to sponsor the Project, of all
permits and approvals required to proceed with
the Project and all approvals and- permits
necessary to accomplish the requirements of this
Agreement.
(d) The reasonable satisfaction of the Seller that
the performance of the terms of this Agreement
will be forthcoming.
11. Closing.
(a)
TUT? r7711 7-
SEP 0 2 1999
DIVI&)ASTAL MIANkGrAEtJ,"ti
The parties agree to execute any and all
documents necessary in connection with the
"Reaffirmation of- Seller's Easements and
Development Rights in Figure Eight Island"
(Exhibit "F") simultaneously with the execution
of this Agreement.
The parties agree to execute any and all
documents and papers necessary in connection with
closing the transfer of title and the
8
C1 199i _ documentation of the other agreements herein
within twenty-four (24) -months of the full
,OASTAL
execution of this Agreement; provided, however,
that the time can be extended for an additional
twelve (12) months upon payment of an additional
non-refundable $25,000.00 which will be applied
to the purchase price if the transaction is
closed. At least five (5) business days after
the conditions to be met prior to Closing have
actually been met, the Buyer shall give Seller
notice of such completion. The Closing shall
take place no later than..two (2) weeks after such
notice is actually received by Seller. The
Survey of the property shall be completed by
Buyer, submitted to the Seller and accepted by
both Buyer and Seller no more than seven (7)
calendar days before Closing; but in no event
shall the Survey be commenced by Buyer more than
two (2)-weeks before Closing.
12. Acknowledgement of Effects of the Project on Remaining
Lands of Seller. The Seller acknowledges that the Project could have
unknown and unanticipated effects on the Seller's remaining property
on the north and south side of the Inlet Corridor. The Seller
further acknowledges that erosion is likely to occur on one or both
banks of the new inlet and that such erosion may not be confined
within the Inlet Corridor. Seller and Buyer agree that, as between
Seller and Buyer and their successors and assigns, the parallel
9
boundaries of the Inlet Corridor will remain fixed regardless of
erosion. and accretion, except as specifically provided to the
contrary in this Agreement or the documents associated with the
closing of this Agreement.
13. No Objection by Seller. Seller agrees not to object
to the Project provided the Project occurs within the time.-specified
herein.
14.. Time for Project Completion. The Project must be
substantially completed within twenty-four (24) months of the
closing. If the Project is not substantially completed within
twenty-four (24) months of the closing, the Buyer or its successors
or assigns will reconvey all property rights conveyed under this
Agreement back to Seller, and Buyer and Seller will be relieved of
any further obligations under this Agreement, except the obligations
in Exhibit "F" which will remain in force. Any money paid prior to
that time will not be refunded. The twenty-four (24) month period
will be stayed for up to 36 months during the pendency of any
restraining order or injunction issued by a court of competent
jurisdiction which prohibits any essential part of the Project from
proceeding.
15. Prorations and Adjustments. Ad valorem taxes on the
Inlet Corridor real property shall be paid by Buyer for the calendar
year in which the closing occurs.
16. Title. Title must be delivered at closing in the form
specified in Exhibits hereto, free from any encumbrances which affect
the ability of the Buyer to accomplish the Project. Buyers sole
10
remedy for failure of Seller to deliver title as specified above is
recission of contract. Acceptance by Buyer of the title documents as
specified in the Exhibits shall evidence satisfaction of this
requirement.
17. Labor and Material menIs Liens. Seller shall furnish
at closing an affidavit and indemnification agreement in form
satisfactory to Buyer showing that all labor and materials, if any,
furnished at the direction of Seller to the property within 120 days
prior to the date of closing have been paid for and agreeing to
indemnify Buyer against all loss from any cause or claim arising
therefrom.
18. Closing Expenses. Seller shall pay for the
preparation of the deed or other instruments of conveyance prepared
by Seller or its attorneys and for the excise tax required by law.
Buyer shall pay for preparation of other instruments of conveyance
prepared by Buyer or its attorneys and for the recording fees for all
instruments that are recorded.
19. Assignment. This Agreement may be assigned by Buyer
to New Hanover County. Any other assignment requires the written
agreement of the parties. If assigned by Buyer to New Hanover County
or any other party, the Agreement shall be binding on the assignee
and its successors. Assignment does not relieve Buyer of its
obligations under the Agreement; except that, upon closing of the
transaction, the obligations established in the documents attached
hereto as Exhibits B, D and E will be the obligations only of the
parties to those documents.
11
20. Notice. Whenever, under the terms of this Agreement,
notice is required to be given or a.document is required to be sent
by one party to another, it shall be directed to the individuals at
the address specified below, unless those individuals or their
successors give notice of a change to the other party. Notices must
be in writing and may be sent only by certified mail return receipt
requested, by courier service where the recipient signs for receipt,
or by personal delivery with a written acknowledgement of receipt.
Seller:
George Henry Hutaff Trust No. 2
c/o David Ward
Ward & Smith, P.A.
1001 College Court
P.O. Box 867
New Bern, NC 28563-0867
Buyer:
Figure 11811 Beach Homeowners Association, Inc.
Attention: Administrator
15 Bridge Road-
Wilmington, NC 28411
21. Parties. This Agreement shall be binding upon and
shall inure to the benefit of the parties and their successors and
assigns. As used herein, words in the singular include the plural
and the masculine includes the feminine and neuter genders, as
appropriate. The exhibits attached hereto and incorporated herein by
reference may be amended to reflect changes in the parties that occur -
due to assignment or succession.
22. Survival. If any provision herein contained which by
its nature and effect is required to be observed, kept or performed
after the closing, it shall survive the closing and r' mamma b1ndin
D C 2 1999
12 COASTAL MAN' ;GEVIENT
upon and for the benefit of the parties hereto until fully observed,.
kept or performed.
23, Entire Agreement. The Buyer acknowledges that it-has
inspected the property. This Agreement contains the entire agreement
of the parties and there are no representations, inducements or other
provisions other than those expressed in writing. All changes,
additions or deletions hereto must be in writing and signed by the
parties.
24. Counterparts. This Agreement shall become binding
when it is properly signed by both Buyer and Seller. It is to be
signed in two counterparts with a signed counterpart being retained
by each party hereto.
25. Neadi.ugs. Headings in this Agreement are for
convenience only and shall not be used to interpret or construe its
provisions.
IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be duly executed under seal the day and year first above
written.
BUYER:
FIGURE "8" BEACH HOMANNERS
ASSOCIATION, INC.
(CORPORATE SEAL)
By:
Edw S. Barc a Jr. r ident
Atte
?•' . Secretary
ip
13
2 79°9
n? tF'k€? GEtl1iEN i
SELLER:
GEORGE HENRY HUTAFF TRUST NO. 2 (SEAT,)
BY : 4 Uz'e_ J (SEAS, )
Oliver C. Hutaff, Jr., Trustee
r
BY :
Tabitha H. McEachern, Trustee (SEAL)
?'R? IFoR/?i,q
STATE OF wooW
-?Ci 5 l/inn ?G s COUNTY
lic,
Notary hereby certify that OLI R C. HUTAFF, JR., TRUSTEE UNDER PEO
RGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this Z(v
1999. day of
--7-
My Commission Expires: Notary Publ c
(SEAL)
MOLLY LEE FAULKNEt
Commission # 1225793
z Notary Public - Colifania
Loa Angeles County
MY Carom. EPies J m24,M03

14
NORTH CAROLINA
i ' MO 40-ria V GV' enrnwrv
I r
,
do hereby Certify that en
TABITHA . enc ,
H. MCEA , TRUSTEE a Notary Public,
UMER THE GEORGE
HENRY HUTAFF TRUST NO.
acknowledged the du 2, personally appeared before me this day and
e execution
purposes therein set forth. of the foregoing instrument for the
4UA'& a WITNESS my
4- ,
I i4l"L
My Commission Expires:
to- a - ZvoD
SEAL)
NORTH CARD) INA
ca- M 1uc.f a'?'ZCOUNTY
I,
Public _. of
me
hand and notarial seal this 5th day of
1999.
Notary Public

a Notary
he
R. C. a oA i t State and County, certify that
personall appeared
daY an acknowledged that he is f?
Secretary of Figure "8" Beach Homeowners Association, Inc., a
K' C. Corporation, and that by the authority duly given and
as the act of the Corporation, the foregoing instrument was signed
its name its in
President, sealed with its corporate-seal
and attested by Lj/.. aas its _4 _Adz? t Secretary.
WITHESS my hand and notarial seal, this day of
?Gto f 1999.
My Commission Notary Public
Expires:
(SEAL)
X"\= VIRM\R7C-233 - I7S
15 ?1? I I
2 9 9 9
TOTAL P.03
EXHIBIT "A"
TO AGREEMENT FOR PURCHASE OF
INTERESTS IN REAL PROPERTY BETWEEN
GEORGE HENRY HUTAFF TRUST NO. 2 AND
FIGURE "8," BEACH HOMEOWNERS ASSOCIATION, INC.
Being a tract of land in New Hanover County near Mason Inlet.
To reach the point of beginning, extend the western boundary of the
Chapel Hill Electric Company, Inc. Tract Three, as depicted on a map
in Map Book 23 at Page 93 of the New Hanover County Registry, to the
point where it intersects the mean high water mark of the Atlantic
ocean; thence with the mean high water mark of the Atlantic ocean
southwestward to a point 200 feet from the preceding point, straight
line measurement; said point being the POINT OF BEGINNING. Thence
with the mean high water mark of the Atlantic Ocean southwestward to
a point that is 1,000 feet from the preceding point, straight line
measurement; thence North 56 degrees 18 minutes 20 seconds West
approximately 900 feet to the mean high water mark of Mason Channel,
also known as Banks Channel; thence with the mean high water mark of
Mason Channel or Banks Channel northeastwardly to-a point that bears
North 56 degrees 18 minutes 20 seconds West from the beginning point;
thence South 56 degrees 18 minutes 20 seconds East approximately
1,000 feet to the POINT OF BEGINNING.
Said property being a corridor 1,000 feet wide between parallel lines
extending from the mean high water mark of the Atlantic Ocean to the
mean high water mark of Mason Channel, also known as Banks Channel,
and being located such that the Grantor retains 200 feet of ocean
frontage between the southernmost lot on Figure Eight Island and the
northeastern boundary of the inlet corridor. For purposes of
conveyance in the deed of conveyance, this description will be shown
on a map of survey that is in recordable form to which reference is
made for the description. The parties agree that the mean high water
mark is an ambulatory boundary and that the description will be
located on the ground with reference to the high water mark at the
time specified in paragraph 8 of the Agreement to which this exhibit
is a part.
WAR\SNVIR0N\R96-233-175
i
' j

WHEREAS, Grantor and Grantee wish to maintain fixed.
boundaries for the Inlet Corridor for purposes' of establishing a
location in which Grantee its assigns or others may perform future
projects to maintain or relocate the inlet, subject to a right of re-
entry by Grantor if all or part of the inlet channel moves entirely
outside of the Inlet Corridor and the Grantee or others fail to
restore all or part of the inlet to a location within the Inlet
Corridor within two years after notice from the Grantor; and
WHEREAS, the Grantor, by separate instruments, vjill convey
additional temporary and permanent construction easements to Grantee
or its assigns to enable Grantee or its assigns to use remaining lands
of Grantor for construction of the Project.
NOW, THEREFORE, the Grantor, for a valuable consideration
paid by the Grantee, the receipt of which is acknowledged, has and by
these presents does hereby grant, bargain, sell and convey unto the
Grantee in fee simple all of that certain lot or parcel of land lying
and being in New Hanover County, North Carolina, and being more
particularly described as follows:
[Property to be described in accordance with survey
map and by reference to a recorded survey map.]
The parties agree that the northeastern and southwestern
parallel boundaries that run from the Atlantic Ocean to Mason Channel,
also known as Banks Channel, will remain fixed regardless of whether
the high water mark of Mason Inlet erodes completely into the
adjoining properties such that either or both of said parallel lines
are located below the mean high water mark of navigable waters or
tidal waters. By way of example, but not of limitation, if the waters
of the relocated Mason Inlet erode the northern shoreline of the new
inlet such that the mean high water mark of the inlet extends beyond
the entire northern boundary of the Inlet Corridor into property of
the Grantor, and if the northern shoreline then begins to accrete and
builds southward such that upland property once again appears between
the northeastern boundary of the Inlet Corridor and the high water
mark of the inlet; then the land accreting into the Inlet Corridor
south of the northern boundary of the Inlet Corridor would vest in the
Grantee regardless of any legal principles that might lead to a
different ownership, subject to termination as specified herein. It
is the intention of the parties that the Grantee, its successors and
assigns, will continue to have the necessary property rights to engage
in excavation and filling activities within the Inlet Corridor
regardless of shoreline changes and subject only to the right of re-
entry hereinafter specified. The parties further agree that they will
execute and record any documents necessary to give effect to this
provision should it be reasonably necessary to do so in the future.
The provisions of the previous paragraph notwithstanding,
the parties agree that the Grantor has a right of re-entry
Inlet Corridor upon the occurrence of all of the following events and
2
upon said re-entry, title shall revest in the Grantor, its successors
or assigns:
(a) There exists within the Inlet Corridor an area of land
above the mean high water mark of navigable or tidal
waters that reaches entirely-from the northeastern to
the southwestern Inlet Corridor boundaries; and
(b) The Grantor or its successors or assigns gives written
notice to the Grantee or its successors or assigns
that the condition described in (a) above exists, such
notice being (i) by certified mail or (ii) by personal
service in accordance with rules for service of
summons in civil actions in the General Court of
Justice of North Carolina and being accompanied by a
survey map by a licensed surveyor showing the
condition described in (a) above; and
(c) The notice and map are recorded in the Register of
Deeds of New Hanover County; and
(d) An area of submerged land below the mean high water
mark- extending from Banks Channel to the Atlantic
Ocean at least 200 feet of which lies within the Inlet
Corridor, as measured perpendicular to the
northeastern or southwestern boundaries of the Inlet
Corridor, is not reestablished by act of man or act of
nature within two (2) years from the recording of the
documents described in (c) above as. evidenced by a
notice from Grantee to Grantor in accordance with (b)
above accompanied by a survey showing the submerged
land within the Inlet Corridor and recorded in the
Register of Deeds of New Hanover County within two (2)
years of the document recorded pursuant to (c) above.
TO HAVE AND TO HOLD the above-described lot or parcel of
land, together with all privileges and appurtenances thereunto
belonging, unto the Grantee, its successors and assigns, in fee simple
forever, subject to the following: the lien of New Hanover County ad
valorem taxes for and subsequent years; utility easements
and restrictive covenants of record; all applicable zoning and land
use ordinances, statutes and regulations; the provisions regarding
fixed boundaries and the right of re-entry specified herein.
The Grantor makes no warranty, express or implied, as to
title to the property hereinabove described.
IN WITNESS WHEREOF, the Grantor has caused this instrument
to be duly executed under seal the day and year fir, above written.
V ?? ?;, ? sJ(l\`i j 7
P G r 1999 ? .
?i Y 1 ?et?:?.E .?.-
3 COASTAL MANAGIPMEE i
n ss
ro
GEORGE HENRY HUTAFF TRUST NO. 2 (SEAL)
BY : Oliver C. Hutaf, f , Jr . , Trustee(SEAL)
a.
STATE OF HAWAII
BY : (SEAL)
Tabitha H. McEachern, Trustee
COUNTY
I a Notary Public,
do hereby certify that OLIVER C. HUTAFF, JR., TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my
hand
1999.
and notarial seal this day of
Notary Public
My Commission Expires:
(SEAL)
NORTH CAROLINA
COUNTY
I, , a Notary Public,
do hereby certify that TABITHA H. MCEACHERN, TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
4
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this
day of
,' 1999.
Notary Public
My Commission Expires:
(SEAL)
WM\ENVnMN\R96-233-177
-1 07
1D
y\vl ?
SEEP C 2 1999
MV tsit- c;,4
COASTAL Mf=NA?G--':--iV`EN i
5
EXHIBIT "C"
TO AGREEMENT FOR PURCHASE OF
INTERESTS IN REAL PROPERTY BETWEEN
GEORGE HENRY HUTAFF TRUST NO. 2 AND
FIGURE "8" BEACH HOMEOWNERS ASSOCIATION, INC.
Being a tract of land in New Hanover County near Mason Inlet.
BEGINNING at the point where the southwestern boundary of the Inlet
Corridor described in Exhibit "A" to this Agreement intersects the
mean high water mark of the Atlantic Ocean; thence following the high
water mark of the Atlantic Ocean in a southerly direction and
continuing with the mean high water mark of Mason Inlet in a westerly
direction and continuing with the mean high water mark of Mason
Channel, also known as Banks Channel, in a northerly direction to a
point in the high water mark of Mason Channel or Banks Channel that
bears North 58 degrees 18 minutes 20 seconds West from the point of
beginning; thence South 58 degrees 18 minutes 20 seconds East with
the southwestern boundary of the Inlet Corridor to the point of
BEGINNING.
Said property is all of Seller's property above the mean high water
mark on what is currently the south end of Figure Eight Island and
which lies south of the Inlet Corridor referenced in Exhibit "A" to
this Agreement. For purposes of conveyance of the temporary
construction easement, this description may be shown on a map of
survey that is in recordable form to which reference may be-made for
a description of the property.
The parties agree that the mean high water mark is an ambulatory
boundary and that this description will be located on the ground with
reference to the high water mark at the time of conveyance, rather
than the location of the mean high water mark as of the date of the
execution of the Agreement to which this Exhibit is a part.
WAR\MMTR=\R96-233-176 I - _
`'J EXHIBIT "D"
TO AGREEMENT FOR PURCHASE OF
INTERESTS IN REAL PROPERTY BETWEEN
GEORGE HENRY HUTAFF TRUST NO. 2 AND
GGP`c FIGURE "8" BEACH HOMEOWNERS ASSOCIATION, INC.
Prepared by:
-NC 28402.
W. A. Raney, Jr., Attorney, P.O. Box 1049, Wilmington,
Parcel #: Part of R05200-003-001-000
NORTH CAROLINA
NEW HANOVER COUNPY
TEMPORARY CONSTRUCTION
EASEMENT AND OPTION FOR
FUTURE.CONSTRUCTION EASEMENTS
daTTH of DEED OF EASEMENT AND OPTION made and entered into this
HUTAFF TRUST NO. 2, by OLIVER C. HMAFg, by THE GEORGE HENRY
JR. and TABITHA H. McEACHERN,
TRUSTEES , Grantor; and FIGURE 118" BEACH HOMEOWNERS ASSOCIATION, INC.,
a. North Carolina non-profit corporation of New Hanover County, North
Carolina, Grantee.
W I T N E S S E T H:
WHEREAS, the Grantee and others are undertaking a project to
relocate Mason Inlet to a more northerly location, to improve the
navigation of Mason Creek from the Atlantic Intracoastal Waterway to
the relocated inlet and to use the sand from these dredging activities
to close the existing channel of Mason Inlet and rebuild the ocean
beaches at Figure Eight Island (the Project); and
WHEREAS,
through which the
the Project; and
the Grantor, is the owner of the upland property
new inlet channel is to be cut in connection with
WHEREAS, the Grantor is willing to convey a 1,000-foot wide
Inlet Corridor to Grantee for the excavation of a new inlet channel
provided certain conditions are met; and
WHEREAS, Grantor and Grantee wish to maintain --fixed
boundaries for the Inlet Corridor for purposes of establishing a
location in which Grantee its assigns or others may perform future
projects to maintain or relocate the inlet, subject to a right of re-
entry by Grantor if all or part of the inlet channel moves entirely
outside of the Inlet Corridor and the Grantee or others fail to
restore all or part of the inlet to a location within the Inlet
Corridor within two years after notice from the Grantor; and
WHEREAS, the construction of the Project will require the
Grantee to stockpile material and to undertake construction activities
on the Grantor's remaining property lying south of the Inlet Corridor;
and
WHEREAS, Grantor is willing to convey a temporary
construction easement to Grantee for purposes of undertaking the
Project and to convey an option to Grantee to acquire additional
temporary easements for future Project maintenance.
NOW, THEREFORE, the Grantor, in consideration of the sum of
TEN AND N01100 DOLLARS ($10.00) and other valuable considerations to
it in hand paid by the said Grantee, the receipt and sufficiency of
which is hereby acknowledged, has bargained and sold and by these
presents does hereby bargain, sell and convey unto the Grantee, its
successors and assigns, a temporary construction easement for purposes
of constructing the Project over, across, under and above the property
described as follows:
(Property to be described in accordance with survey
map and by reference to a recorded survey map.)
The rights conveyed by this easement include, but are not
limited to, the right to utilize the property for storage or
stockpiling of sand to be used in closing the existing channel of
Mason Inlet; the right to operate and park all types of equipment and
machinery used in connection with the Project; the right to grade and
slope the property to meet the design standards for the Project; and
the right to engage in all other activities reasonably necessary for
construction of the Project; provided the overall elevation and
quantity of sand remaining above the mean high water mark on the tract
after the Project is equal to or exceeds the amount that existed on
the property prior to the Project. The easement specifically does not
include a right of access or use by the general public. All
equipment, tangible personal property, and structures must be removed
within thirty (30) calendar days after the completion of the Project
and within a like time upon the completion of the maintenance or
reconstruction of the Project which led to the exercise of any one or
more periods within the Option.
The easement expires upon completion of the Project in
accordance with all regulatory permits, but in no event longer than
twenty-four (24) months after recording of this easement in the
Register of Deeds of New Hanover County; provided the twenty-four (24)
month period will be stayed for up to thirty-six (36) months during
the pendency of any restraining order or temporary injunction which
prohibits any essential part of the Project from proceeding.
The Grantor also conveys to the Grantee, its successors and
assigns, an Option to acquire future temporary construction easements
on the property on the same terms and conditions as this easement
except as to price and payment. The easements shall be for the sole
purpose of engaging in maintenance or reconstruction of the Project
2
from time to time. Maintenance and reconstruction shall include a
right to fill or place sand on the property but not the right. to
reduce the overall size or elevation of the property as it exists at
the time of maintenance or reconstruction. The Option shall extend
for thirty (30) years from the date of the recording of this easement
and option. The option may be exercised by notice to Grantor, its
successors and assigns, by Grantee, its successors and assigns,
certified mail or personal delive by
Grantee to Grantor at least sixty Such notice shall be given by
maintenance or reconstruction are scheduled to begin on the property.
The price for the initial twenty-four (24) months of the easement
shall be $55,000.00 for each twelve (12) month calendar year period or
portion thereof that the easement is in effect. The per year
consideration of the initial twenty-four (24) months shall be donated
to New Hanover County or alternate sponsor approved by Grantor. The
price for subsequent easements shall be
months or portion thereof that the easement0 is for in ceffect twelve (12)
easement will expire at the end of the term or upon the completionTof
the Project as indicated above, whichever occurs sooner.
The Option will expire and be void and of no further effect
if the Grantor exercises the right of re-entry of the Inlet Corridor
property conveyed by Grantor to Grantee by deed recorded in Book
at Page of the New Hanover Count Re
which property lies immediately north of the property that is subject
to this easement.
The Granteeand its successors, assigns and licensees, and
contractors or agents of Grantee utilizing said easement, to the
extent authorized by law, fully indemnify and hold the Grantor, its
successors and assign, harmless from all claims, expenses, costs and
liabilities arising out of the use of the easement area under the
terms of this easement and Grantee executes this easement to accept
this obligation.
TO HAVE AND TO HOLD the above granted and described
Temporary Construction Easement and Option unto the Grantee, its
successors and assigns.
IN TESTIMONY WHEREOF, the Grantors have caused this
Temporary Construction Easement and Option to be signed by themselves
as Trustees under the George Henry Hutaff Trust No. 2 and sealed the
day and year first above written.
f L
? ?`. 2 19 9 ?J
GEORGE HENRY HUTAFF TRUST NO. 2 (SEAL)
BY (SEAL)
Oliver C. Hutaff, Jr., Trustee
BY: (SEAL)
Tabitha H. McEachern, Trustee
FIGURE "8" BEACH HOMEOWNERS ASSOCIATION,
INC.
BY:
President
(Corporate Seal)
Attest:
Secretary
STATE OF HAWAII
COUNTY
I' , a Notary Public,
do hereby certify that OLIVER C. HUTAFF, JR., TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this
11 1999.
My Commission Expires:
(SEAL)
day of
Notary Public

NORTH CAROLINA
COUNTY
I,
do hereby certify that TABITHA H. Mc RN, TRUSTEE 11 a UNDER Notary Public,
GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set.forth.
WITNESS my hand and notarial seal this
1999 . day of
Notary Public
My Commission Expires:
(SEAL)
NORTH CAROLINA
COUNTY
I,
11
Public of the aforesaid State and County a Notary
, certify that
before me this day and acknowledged that he p issonally appeared
Secretary of Figure 118" Beach Homeowners Association, _Inc., a
Corporation, and that by the authority duly given and
as the act of the Corporation, the foregoing instrument was signed in
its name by its President, sealed with its corporate seal
and attested by self as its Secretary.
WITNESS my hand and notarial seal, this day of
1999.
M Notary Public
y Commission Expires:
(SEAL)
NAMM MM\R96-233-178
7,77
1009 Z?L-?
? i
EXHIBIT "E"
TO AGREEMENT OF PURCHASE OF
INTERESTS IN REAL PROPERTY BETWEEN
? GEORGE HENRY HUTAFF 'T'RUST NO. 2 AND
FIGURE "S" BEACH HOMEOWNERS ASSOCIATION, INC.
Prepared by: W. A. Raney, Jr., Attorney, P.O. Box 1049, Wilmington,
NC 28402.
Parcel No. Part of
!.,
NORTH CAROLINA
NEW HANOVER COUNTY
DEED OF EASEMENT
(751 Beachfront)
THIS DEED OF EASEMENT made and entered into this day
of 1999 by the GEORGE HENRY HUTAFF TRUST NO.
2, by OLIVER C. HUTAFF, JR; and TABITHA H. McEACHERN, TRUSTEES,
Grantor; and FIGURE "8" BEACH HOMEOWNERS ASSOCIATION, INC., a North
Carolina non-profit corporation, whose address is 15 Bridge Road,
Wilmington, NC 28411, Grantee.
W I T N E S S E T H:
That the Grantor, in consideration of the sum of TEN AND
N01100 DOLLARS ($10.00) and other valuable considerations to it in
-hand paid by the said Grantee, the receipt of which is hereby
acknowledged, has bargained and sold and by these presents does hereby
bargain, sell and convey unto the Grantee, its successors and assigns,
a certain 75-fo6t wide easement landward from the mean high water mark
of the Atlantic Ocean across the lands of the Grantor located in New
Hanover County and described on Exhibit "A" attached hereto and
incorporated herein by reference. The easement shall be for the
purpose of enabling the Grantee, its successors, assigns and licensees
to lay dredge pipeline, operate equipment and machinery, temporarily
stockpile materials and equipment, place soil in connection with beach
nourishment and undertake related activities to engage in beach
nourishment within the easement and on oceanfront areas north, east
and south of the easement property. This easement is granted subject
to the following conditions:
1. Any activities undertaken by the Grantee, its
successors, assigns or licensees shall be performed in accordance with
all applicable governmental regulatory programs and permits issued
pursuant thereto.
2. The Grantee, its successors, assigns and licensees may
not construct any permanent structures within the easement area. Any
temporary structures, pipe or other items placed within the easement
area must be removed within two months after cessation of active
pumping or related activity over or on the easement area for a period
of seven (7) consecutive calendar days related to any authorized
project utilizing the easement area.
3. The Granteeand its successors, assigns and licensees,
and contractors or agents of Grantee utilizing said easement, to the
extent authorized by _law, fully indemnify and hold the Grantor, its
successors and assigns, harmless from all claims, expenses, costs and
liabilities arising out of the use of the easement area under the
terms of this easement. -
4. The Grantor, its successors and assigns are not
prohibited from constructing structures within the easement area. If
structures are built within the easement area by Grantor, its
successors and assigns, the Grantee shall undertake all activities
2
permitted by this easement in an area at least 20 feet seaward of such
structures unless permission is given by the owner of the structure to
work in closer proximity to the structure.
5. To the extent authorized by law, this easement will
continue to exist within the area described on Exhibit "A" even if one
or more of the boundaries of the easement becomes submerged-below the
mean high water mark of navigable waters.
6. This easement shall terminate if the 1000' Inlet
Corridor conveyed by,Grantor to New Hanover County by deed recorded in
Book at Page of the New Hanover County Registry is
re-entered by Grantor or its successor under the terms of said deed.
TO HAVE AND TO HOLD the above granted and described easement
and right-of-way unto the Grantee, its successors and assigns,
forever; it being agreed that the easement hereby granted is
appurtenant to and runs with the land owned by the Grantee, or parts
thereof which may hereafter be conveyed by the Grantee.
IN TESTIMONY WHEREOF, the Grantor, GEORGE HENRY HUTAFF TRUST
NO. 2, has caused this Deed of Easement to be signed in its name by
its Trustees and the Grantee, has caused this instrument to be signed
by the President, attested by is Secretary and its corporate seal
attached the day and year first above written.
FIGURE 118" BEACH HOMEOWNERS
ASSOCIATION, INC.
(CORPORATE SEAL)
By:
President
-?" 71
COASTAL M pp A"VriEIN i
ATTEST:
Secretary
GEORGE HENRY HUTAFF TRUST NO. 2 (SEAL)
c.
By (SEAL)
Oliver C. Hutaff, Jr-, Trustee
By : (SEAL)
Tabitha H. McEachern, Trustee
STATE OF HAWAII
COUNTY
I' a Notary Public,
do hereby certify that OLIVER C. HUTAFF, JR., TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal .this
01 1999.
My Commission Expires:
( SEAL )
day of
Notary Public
4
- - -? emu
:.'. lJ99 ---i
NORTH CAROLINA
COUNTY
I, , a Notary Public,
do hereby certify that TABITHA H. McEACHERN, TRUSTEE UNDER -THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and_
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this day of
1999.
Notary Public
My Commission Expires:
(SEAL)
NORTH CAROLINA
COUNTY
I, .
Public of the aforesaid State and County a Notary 11
, certify that
before me this day and acknowledged that he P issonally_appeared
Secretary of Figure 118" Beach Homeowners Association, Inc., a
Corporation, and that by the authority duly given and
as the act of the Corporation, the foregoing instrument was signed in
its name by its President, sealed with its corporate seal
and attested by self as its Secretary.
WITNESS my hand and notarial seal, this day of
, 1999.
My Commission Expires:
(SEAL)
WAR\MVZR MX96-233-008 -
77T of T
? '? fI
?` ?} `! '
5 lz °
rt:.' `?C'4V E!"L?•!?•E ril yi.'?i ? v EE NIT
EXHIBIT "A"
to Deed of Easement (75' Beachfront)
between George Henry Hutaff Trust No. 2
and Figure "8" Beach Homeowners Association, Inc.
BEGINNING at the point where the northwestern boundary of the Inlet
Corridor as described in an instrument recorded in Book
Page . of the New Hanover Count Re at
gist inters-e`ctls-?the
high water mark of the Atlantic Ocean Y the
nce northwardly with mthe
mean high water mark of the Atlantic Ocean to the point where the
western boundary of the Chapel Hill Electric Company, Inc. Tract Three
as depicted on a map in Map Book 23 at Page 93 of the New Hanover
County Registry intersects the mean high water mark of the Atlantic
Ocean; thence- with said western boundary of the Chapel Hill Electric
Company Tract Three to a point 75 feet from the mean high water mark
of the Atlantic Ocean measured on a line bearing South 56 degrees 18
minutes 20 seconds East. Thence southwardly along the line lying 75
feet from the mean high water mark of the Atlantic Ocean to the
northern line of the Inlet Corridor as described in Book
Page of the New Hanover Count Re at
with the northern line of said Inlet Corr
gitry; idor toe the ep intr of
BEGINNING. Said property being a 75-foot wide strip bounded on the
southeast by the mean high water mark of the Atlantic Ocean and
extending from the Inlet Corridor referenced above on the southwestern
end to the Chapel Hill Electric Company Tract Three as referenced
above on the northern end. The parties agree that the mean high water
mark is an ambulatory boundary- and that the description will be
located on the ground with reference to the high water mark as it may
move.
6 ?.. -

EXHIBIT "F"
LTO AGREEMENT FOR PURCHASE OF INTERESTS IN REAL PROPERTY BETWEEN
GEORGE HENRY HUTAFF TRUST NO. 2 AND
FIGURE "8" BEACH HOMEOWNERS ASSOCIATION, INC.
Prepared by: W. A. Raney, Jr., Attorney.
STATE OF NORTH CAROLINA
COUNTY OF NEW HANOVER AGREEMENT
This Agreement, effective as of the day it is fully
executed and recorded in the office of the New Hanover County
Register of Deeds, by and between FIGURE "8" BEACH HOXEoww R3
ASSOCIATION, INC., a North Carolina non-profit corporation
(Association), and GEORGE HENRY HUTAFF TRUST NO. 2 by OLIVER C.
HUTAFF, JR. and TABITBA H. McEpcmM, TRUSTEES (Trustees).
W I T N E S S E T H:
WHEREAS, Figure Eight Island has been subdivided by various
developers who have imposed various restrictive covenants on the
subdivision property and have granted various rights to the use of
common property which has not been subdivided into building lots; and
WHEREAS, the last in a succession of developers of Figure
Eight Island assigned the rights and obligations of the developer/
declarant for Figure Eight Island subdivision to the Association by
instrument recorded in Book 1248 at Page 1665 of the New Hanover
County Registry; and
WHEREAS, the Trustees hold in trust real property located
on the southern end of Figure Eight Island which has never been
subdivided or incorporated into the Figure Eight Island Subdivision
or made subject to the restrictive covenants applicable to Figure
Eight Island Subdivision (the Property or Trustees' Property); and
WHEREAS, the Trustees predecessors in title, Oliver C.
Hutaff et al, and one of the Association's predecessors in title, B.
B. Cameron et al, granted mutual easements establishing rights-of-way
over their respective properties for the purpose of buil8ing roads
and bridges, said easements being recorded in Book 600 at Page 67 of
the New Hanover County Registry; and
WHEREAS, the Trustees and The Figure Eight Island Company,
another predecessor in title of the Association, entered into an
Agreement recorded in Book 954 at Page 255 of the New Hanover County
Registry by which the parties released certain easements and
established certain rights and obligations of the parties with
respect to access to and development of Trustees' Property on Figure
Eight Island (herein the 111972 Agreement"); and
WHEREAS the parties wish to reaffirm, clarify and amend
the 1972 Agreement to more precisely identify and expand the rights
and obligations of the parties with respect to each other. -
NOW, THEREFORE, in consideration of the mutual promises and
conditions set forth and the sum of TEN DOLLARS ($10.00) paid by each
party to the other, the receipt and sufficiency of which are hereby
acknowledged, the parties agree as follows:
1. The "Whereas" clauses set forth above in this
Agreement are incorporated in the Agreement by reference.
. 2. The Association and the Trustees affirm the provisions
of paragraphs 2., 3. and 4. of the 1972 Agreement recorded in
Book 954 at Page 255 of the New Hanover County Registry.
2
3. In order to clarify and expand on the agreements set
out in Book 954 at Page 255, the parties agree as follows:
a. The Association will provide at no cost all
required utility easements to any utility company or utility
provider to enable such company or provider to provide utility
services to Trustees' property as may be necessary or"-desirable
for development of Trustees' property for single family
residential uses.
b. In addition to the right to connect to the water
system of Figure Eight Island as specified in paragraph 3 of the
1972 Agreement, the Association will make available and provide
to the north property line of the Trustees' property at the
point where the access easement described in the 1972 Agreement
adjoins, or if extended would adjoin, which access easement is
confirmed to adjoin, the -Trustees' property, the following
utilities which are now available or which may become available
in the future, at no additional cost, except the same connection
fees as would be charged an owner of a lot in Figure Eight
Island Subdivision for the same service,, and without any
assessment or additional charge for construction or availability
fees:
(i) potable water;
(ii) sewer to the extent provided to lots in
Figure Eight Island Subdivision;
(iii) electricity;
(iv) cable television and telephone lines;
3
(v) all other utilities available to owners
of lots on Figure Eight Island.
The provided utilities would have the capacity to
service and accommodate reasonable single family residential
development of the Trustee's Property.
c. Prior to improvement of the Trustees R- Property
for single family residential use, access to the Trustees'
Property over the easements described in the 1972 Agreement is
available only to the Trustees, the Trustees' immediate family,
the beneficiaries of the Trust, any guests of the Trustees or
beneficiaries when accompanied by a Trustee or beneficiary, any
other person who becomes an owner of any part of the Trustees'
Property, and any agent or employee of the Trustees who is
engaged in business related to the Property. The Trustees will
provide to the Association-a list of those entitled to access
and shall update the list periodically.
d. Prior to improvement of the Trustees' Property
for single family residential use, the Trustees shall
obligated to pay assessments levied by the Association against
lots on Figure Eight Island. At such time as a building permit
is issued for construction of each single family residence on
the -,Trustees' property, such single family residence will be
subject to assessments by the Association in an amount necessary
to fund a pro-rata share of any expenditures by the Association
relating to maintenance, repair and operation of the bridge and
roads owned and operated by the Association. Such assessment
shall be calculated annually and paid in arrears. All users of
4
the bridge and roads owned by the Association will abide by any
rules and regulations regarding their use to the same extent as
lot owners in Figure Eight Island Subdivision.
e. The owners of single family residences on
Trustees' Property shall be entitled to trash removal services
to the extent and under the same terms as the lot '-owners in
Figure Eight Island Subdivision upon the payment of applicable
fees.
f. The Association will not object to the Trustees'
development of the Trustees' Property into single family
residential use in accordance with all applicable governmental
statutes, ordinances, rules and regulations.
4. This Agreement is binding upon and shall inure to the
benefit of the parties, their successors and assigns, is effective
immediately upon being signed by both parties, and shall be
appurtenant to and run with the property owned by the Association and
the Trustees as identified herein.
5. The provisions of the 1972 Agreement recorded in Book
954 at Page 255 continue in effect except to the extent they are
inconsistent with the provisions of this Agreement, in which case the
provisions of this Agreement will prevail.
IN WITNESS WHEREOF, the Association has caused this
instrument to be signed by its President, attested by its
Secretary, and its corporate seal attached, and the
Trustees have hereunto set their hands and seals, effective as
indicated herein.
v SEP C2 1999
5 9,QASTI-A `&MANAGEMENT
FIGURE "8" BEACH HOMEOWNERS
ASSOCIATION, INC.
(CORPORATE SEAL)
By:
President
ATTEST:
c
Secretary
GEORGE HENRY HUTAFF TRUST NO. 2 (SEAL)
By' (SEAL)
Oliver C. Hutaff, Jr., Trustee
By : (SEAL)
Tabitha H. McEachern, Trustee
u t 2 I.E9?
6
STATE OF HAWAII
COUNTY
I, , a Notary Public,
do hereby certify that OLIVER C. HUTAFF, JR., TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this
1999. ---E-_Y of
Notary Public
My Commission Expires:
(SEAL)
NORTH CAROLINA
COUNTY
I' - , a Notary Public,
do hereby certify that TABITHA H. MCEACHERN, TRUSTEE UNDER THE GEORGE
HENRY HUTAFF TRUST NO. 2, personally appeared before me this day and
acknowledged the due execution of the foregoing instrument for the
purposes therein set forth.
WITNESS my hand and notarial seal this day of
1999.
Notary Public
My Commission Expires:
(SEAL)
11 12 1-99
7

NORTH CAROLINA
COUNTY
I,
Public of the aforesaid State and Count a Notary
y, certify that
before me this day and acknowledged that he P issonally appeared
Secretary of Figure "8" Beach Homeowners Association, Inc., a
Corporation, and that by the authority duly given and
as the act of the Corporation, the foregoing instrument waste-signed in
its name by its President, sealed with its corporate seal
and attested by self as its Secretary.
WITNESS my hand and notarial seal, this day of
1999.
My Commission Expires: Notary Public
(SEAL)
AR\MMnM\R96-233-160
I` f l 77,
S F P C 2 '1999
8 COt S T P"IL ttIANAC.,CMENT
:TH CAROLINA
ASSIGNMENT OF CONTRACT
:W HANOVER
Freement made this day of 1999,
Hanover County, a unit of government of the State of North
)unty), and Figure 118" Beach Homeowners Association, Inc.,
)lina non-profit corporation (Association);
W I T N E S S E T H•
IEREAS, the County is pursuing an erosion control project
in part 'of relocating Mason Inlet to a more northerly
i depositing excess sand on the ocean beaches of Figure
I (the Project); and
IEREAS, the' Association has negotiated a contract to
operty rights from the George Henry Hutaff Trust No. 2
are necessary for the construction of the Project, a copy
attached hereto and incorporated herein by reference as
ind
IEREAS, the Association wishes to assign its rights and
under the contract to the County and the County wishes to
rights and obligations; and
iEREAS, the Association has made the $40,000.00 down payment
the contract which sum is part of the total project cost
ie allocated to the properties benefited by the project; and
IEREAS, it is appropriate for the County to reimburse the
for its expenses when and if the transaction is closed and
$40, 0,000 with the other project costs in determining the
(?)
to be recovered from the benefited properties through
',0A E i
NOW, THEREFORE, the parties in consideration of one dollar
and other valuable considerations agree as follows:
1. The Association hereby conveys all of its right, title
and interest,in the contract to the County with the exception of those
matters relating to agreements between the Trust and the Association
involving access to and development of the Trust property on-the south
end of Figure Eight Island as addressed in paragraphs 9, ii(a), and 19
of the contract and in Exhibit F of the contract.
2. The County hereby accepts the assignment of the contract
and assumes the rights and obligations of the Association under the
contract except as set forth in paragraph 1 above.
3. The county will reimburse the Association the $40,000
non-refundable deposit paid by the Association upon the closing of the
transaction but will not be obligated to make such reimbursement if the
transaction does not close.
4. If the County decides not to close the transaction it
will assign the contract back to the Association, if the Association so
requests.
IN WITNESS WHEREOF, the parties have hereunto executed this
agreement in appropriate form effective the day and year above written.
FIGURE EIGHT BEACH HOMEOWNERS
ASSOCIATION
CORPORATE SEAL
By:
Edward S. Barclay, III
President
jli? L V11 LL
I?
I'
SF t 2 1999 J
COASTAL (v AINAG=DAENT
ATTEST:
Secretary
NEW HANOVER COUNTY
By:
ATTEST:
WAR\ENVIRON\R96-233-183
< <i
2
F
FIGURE "8" BEACH HOMEOWNERS' ASSOCIATION, INC.
15 Bridge Road • Wilmington, North Carolina 28411 • Telephone [phone]
FAX [phone]
August 18, 1999
Mr. Allen O'Neal
New Hanover County Manager
320 Chestnut Street
Wilmington, NC 28401
Re: Mason Inlet Relocation Project
Dear Mr. O'Neal:
APPENDIX "C"
As you know, the Figure "8" Beach Homeowners' Association, Inc. (Association) has been an active
participant in the planning of the Mason Inlet Relocation Project. The Association has a vital interest
in the portion of the project which will result in the placement of sand on Figure Eight's ocean
beaches. Accordingly, the Association approves the placement of sand resulting from the project on
the ocean beaches at Figure Eight.
It is the understanding of the Association that the sand will be placed on the southern portion of Figure
Eight Island and that the rate of placement will not exceed fifty cubic yards per linear foot of beach.
We understand that the linear extent of placement and the rate of placement will be somewhat
dependent on the quantity of sand available. The Association would like to continue to work with the
County's consulting engineer concerning the rate of placement and the linear extent of placement.
If you require further information from us, please do not hesitate to contact me or the Island
Administrator, Art Poineau.
Sincerely,
Figure "8'' Beach Homeowners'
Association, Inc.
Edwa . Barcla , Jr.
Pres' ent
cc: Dave Weaver
414 Chestnut Street
Wilmington, NC 28401
Karyn Erickson
201 N. Front Street, Suite 201
Wilmington, NC 28401
' 1 _ '` _
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AGENDA
MEETING BETWEEN REPRESENTATIVES OF NEW EMOVER COUNTY
AND REPRESENTATIVES OF DEPARTMENT OF ENVIRONMENT
AND NATURAL RESOURCES
MASON INLET RELOCATION PROJECT
FEBRUARY 22, 2000
?1 .
'/2.
V3 .
Introductions
Status Report on Federal Agencies
Comments and County responses
Status Report on State Agency
Comments and County responses
Raney and Smith
Erickson
Erickson
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4.
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L,6
1J4 .
Plan for developing revised EA
Procedure for evaluation of EA
and permit application by the
State
Water quality certification
issues introduced
Water quality certification -
"Practical alternatives"
discussion
Mitigation discussion
?. Division of Marine Fisheries
Additional issues
`1`0. DCM additional issues
-?1. WRC additional issues
LA2. Conclusion
Erickson
Moffitt or designee
Raney
Erickson/group discussion
Morrison/Erickson/group
discussion
Marine Fisheries Rep
DCM Representative
WRC Representative
WAR\environ\R96-233-191
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Technical Review
Mason Inlet Relocation Project
Prepared by
John S. Fisher, Ph.D., P.E.
January 2000
For
New Hanover County
Engineering Department
Wilmington, NC
105 White Oak Court
Chocowinity, NC 27817
252 946 1839
j ohn_fisher@coastalnet. com
Technical Review
Mason Inlet Relocation Project
I. Background
At the request of the Engineering Department, New Hanover County, I have been retained to review the
engineering aspects of the Environmental Assessment (EA) prepared by Applied Technology and
Management of North Carolina, Inc. (ATM) for the Mason Inlet Relocation Project. This review includes
the EA, the Hydrodynamic Modeling Report, and related Comments and Responses of the various state and
federal reviewing agencies.
IL Summary of Review
The objectives of this proposed project are to remove the immediate threat of the loss of the north end of
Wrightsville Beach due to the south migration of Mason Inlet and to nourish the beach on Figure Eight
Island. The project proposes to shift the current position of Mason Inlet approximately 3,000 ft to the
north, fill the existing inlet, dredge Mason Creek, and use a portion of the dredged material$ to no s?the > > p?
Figure 8 Island beach. ?(tl vr'a C? ?I
In simple terms the project is desi ed to mimic what might be expected to ha en ' a severe storm ' the
current spit on the sou en of Figure Eight Island were overwashed, resulting in the na a s i mg of S ( ACC TG
Mason Inlet back to the north. In addition, the project is designed to restore the flushing through M son +?A s
C3oek that is presumed to have been in place prior to the shoaling of this connection to the Intracoastal 0 c t
Waterway. The placement of sand on Figure Eight is a logical use of the excess dredged materials, and can "O'V(,
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b viewed as a restoration of this erod' g shoreline. u W (? V t+?,} ?/?p? S n ?9
W ??es i{ ???? C aack,o 9c ?aa n fit,
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Un rtunately, our current level of understanding of coastal processes and tidal hydrodynamics precludes
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our ability to construct exact computer models of these complex flows and sediment transport mechanisms. ??
Coastal engineers have to rely on a combination of experience, computer simulations, analysis of the
historical changes at the project site, and to some degree, a willingness to "fine tune" the project after initial AaG -f OIR71
?1 c? 8
construction. This is the general approach used by ATM for this project.
In general, it is my opinion that the project design and analysis prepared by ATM for this project meets or ?d ccQ. t
exceeds what one could expect from a qualified coastal engineering fum with extensive experience dealing
with these kinds of projects. The hydrodynamic-model used is recognized as being appropriate given our
AJ current level of understanding. The analysis of the inlet dynamics is consistent with the known behavior of I (? ?(q
this inlet as determined from the historical record.
There are a few items in the EA and the supporting documents that could be enhanced in order to clarify ?d 57a?1 CZQ
the reasons cited for some of the design decisions and the expected outcomes. Specifically: ?- 5 }
1. The choice for the design width of 500 ft for the relocated inlet is not well documented.
2. The probable changes in the Figure 8 Island shoreline after nourishment are not adequately
discussed.
3. The impacts of one or more severe storms (greater than Category 2) are not discussed, either on
the relocated inlet or the nourished shoreline.
The impacts of the project on the shoreline south of the Shell Island Resort are not adequately
addressed.
5. Wa quality modeling should be used to document the suggested improvement in water quality
due to roved flushing in the estuary. j Da? iG sin t S
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6. Given the anticipated delay in proceeding with the project, additional focus should be placed on
the consequences of this delay to the threatened shorelines.
These suggestions for additional information could be readily incorporated in a revised EA.
III. Detailed Comments for Each Document Reviewed
Reports Reviewed and Detailed Notes: (Dates are either on Reports or Letter of Transmittal to JSF)
Environmental Assessment Mason Inlet Relocation Proiect
ATM - October 1999
1. Purpose
The stated purpose of the EA is to provide an analysis of the environmental consequences of the proposed
relocation of Mason Inlet and the dredging of Mason Creek. The EA also considers the proposed
environmental affects of the beach nourishment of a portion of Figure 8 Island. The plans call for
relocating the inlet 3,000 ft to the north, to approximately its 1986 position. The goals of the project are
listed as:
1. Halt inlet migration, and thus remove the threat to the property south of the inlet,
2. Reopen Mason Creek,
3. Restore beaches for recreational use,
4. Minimize sand coverage of biological resources,
5. Nourish Figure 8 Island
The EA presents a comprehensive analysis of a plan to achieve these goals. This analysis includes
hydrodynamic modeling of the tidal flushing in the inlet and estuary, review of the history of the inlet's
migration patterns, compilation of the storm and wave climate for the study area, and a discussion of the
alternatives considered and the reasons for the proposed design.
2. Existing Environment
An important part of the engineering analysis is the collection of the historical data and the acquisition of
the field data needed to develop the final design --These data included tide measurements, wave data, - -
bathymetry, topography, and historical aerial photographs. ATM has done a reasonable job in this data
collection, and the data appear to be adequate to do an analysis of the proposed design
The field measurements of the tidal elevations are needed for the development and calibration of the
computer model of the tidal hydrodynamics. While the time period for the data collected by ATM was
limited, it appears to have been adequate based upon the comparisons between model simulations and
recorded tides. This issue is discussed later in this review.
The ATM discussion of the current and historical geomorphology of the study area is an important part of
the EA. It is fortunate that there is such a rich database of aerial photography. These photographs coupled
with the earlier report by Cleary and Hosier (1990) "A Long Range Plan for Channel Maintenance and
Beach Restoration Figure 8 Island, North Carolina" enable ATM to do a thorough analysis of the migration
patterns for Mason Inlet. The discussion and the conclusions regarding the nature of this inlet migration,
the rates of migration, and the relationship between the inlet and the flow in Mason Inlet appear to be
reasonable. In particular, the conclusion that Mason Inlet is unstable, that it is a sink for sand moving to the
inlet from the north, and that the inlet can be expected to continue to migrate to the south (if the structures
are removed) is warranted.
3. Need for Action
A. Wrightsville Beach
The EA concludes that something must be done to stop the continued migration of Mason Inlet. Otherwise,
one can reasonably expect the present geotextile tubes protecting the Shell Island Resort to fail, and this
would in turn lead to the ultimate structural failure of the resort and the eventual loss of other downdrift
properties. Both engineering judgement and common sense suggests that this is a valid conclusion. In fact,
there should be considerable thought given to the maintenance and repair of these geotextile tubes given the
fact that this project, if approved, will not be initiated until after the next hurricane season. One can only
speculate if a Category II or III hurricane might cause significant damage to the Shell Island Resort even if
such repairs are made. Given that the data suggest that North Carolina is experiencing a period of frequent
and intense hurricanes, this action needs to be given serious consideration.
B. Figure 8 Island
The use of beach nourishment as an effective tool to protect oceanfront property is a well-established fact
in coastal engineering practice. Figure 8 Island has used nourishment many tines in the past, and this
project will provide an excellent opportunity to nourish this beach once again.
Discussion of the Need for Action
The EA is based in part on the premise that if there is an economically justified opportunity to alter the
natural process of inlet migration and to undertake beach nourishment in a way that does not have
significant adverse environmental consequences, then such action is warranted. Obviously, as discussed in
Section 4 of the EA, "Alternative Analysis", one could always let the natural processes proceed without
intervention. The decision to do this is not a question of engineering design, but rather one of societal
judgements. While some might conclude that there is a greater long term good from letting the system
proceed without interference, others elect to use engineering works to modify the natural processes.
4. Alternatives
The EA presents 7 alternatives. These alternatives include no action, inlet closure, inlet stabilization and a
number of inlet relocation scenarios. The Preferred Alternative is inlet relocation.
A. No Action
The EA concludes that just letting the inlet migrate with the eventual loss of the property on the north end
of Wrightsville Beach is not appropriate. Again, this conclusion is based upon the assumption that in this
case it is better to use engineering works to alter the natural processes. The economic consequences of this
"no action" plan would seem to justify this conclusion. This is not an engineering decision.
It should be noted that the EA assumes that if the inlet is not relocated by overt action then it will continue
to migrate to the south unchecked. While this may indeed happen, one could also speculate that a major
storm would cut through the prograding spit moving south from Figure 8 Island and thus halt this
migration. If and when this might occur is impossible to predict.
B. Training Groin
The EA discusses the use of a terminal groin to arrest the migration of the inlet. This is the type of
structure that was constructed to halt the migration of Oregon Inlet on the Outer Banks. There is little
doubt that this type of structure could be used successfully at Mason Inlet. However, as correctly presented
in the EA, it is unlikely that a CAMA permit could be obtained for this structure due to the fact that it
would be primarily used to protect private rather than public property.
C. Inlet Closure
The EA states that if the inlet were closed several of the project objectives would be realized. Namely, the
threat to the north end of Wrightsville Beach would be resolved and sand would be able to move from
Figure 8 to the adjacent downdrift beaches. The closure of Mason Inlet would not provide for additional
flushing of the estuaries. The EA argues that the reduction in flushing would lead to adverse environmental
impacts. While this conclusion is speculative, it is probably correct. In addition, all recreational use of the
inlet would be lost. Thus, in the context of the stated objectives of the project, inlet closure is not an
appropriate alternative.
D. Preferred Alternative - Relocation of Mason Inlet
The EA presents the results of the analysis of a series of possible combinations for relocated inlet
dimensions, dredging options for Mason Creek and a proposed sedimentation basin. A major portion of
this analysis is based upon a computer model for the hydrodynamics of the inlet and the adjacent estuary.
A discussion of the model, calibration and application is presented in a later section of this review. The
present section considers the scenarios presented in the EA. Several additional scenarios are presented in
an ATM supplement to the EA, and are discussed later in this review.
There are three principal design components of the project: the dimensions of the relocated inlet,
sedimentation basin location and dimensions and the depth of dredging of Mason Creek. The EA assumes
that all three components are needed for a successful project. The need for the new inlet is self-evident.
The need for the dredging of Mason Creek and the construction of the sedimentation basin are less obvious.
Mason Creek Dredging
One of the principal explanations for the relatively rapid migration of Mason Inlet in recent years is the
shoaling of Mason Creek and the subsequent reduction in tidal prism. This conclusion is supported by the
analysis of the historical aerial photographs of the study area. I agree with this conclusion although the
presentation in the EA would benefit from additional supporting documentation. The EA argues that the
increase in tidal prism realized by the dredging of Mason Creek is essential if the relocated inlet is to have a
lower rate of migration than present. I agree with this conclusion as well, although here too the EA would C
benefit from a more thorough discussion of this relationship. ? i o ?p ?5Cpsf k
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Sedimentation Basin r6 Cp ?ks¢ 5 ln?( /ld c7v W5 J,
The EA states " A sedimentation basin is critical to capturing and containing sand flows entering the inlet
to reduce sand losses to Mason Creek and the interior marsh areas." The basis for the decision to add the
sedimentation basin to the project appears to be based upon the historical analysis of the geomorphology of
the study area. It is entirely logical to assume that if Mason Creek is to be dredged and kept open, then
some action must be taken to trap sediments moving through the inlet on flood tide and therefore restricting
these sediments from reaching Mason Creek. The sedimentation basin will also serve as an efficient source
of nourishment material for Figure 8 Island. Given the multiple objectives of the project, and the assumed
relationship between Mason Inlet and Mason Creek, the stated importance of the sedimentation basin is
reasonable. The EA is correct in that one can only speculate as to how long it will take for the
sedimentation basin to fill. The stated period is 3 to 5 years, and this is a reasonable estimate although the
actual time will depend upon the storm climate for this period.
Design Scenarios for the Relocated Inlet
A total of 12 scenarios are presented in the EA. These alternative computer simulations vary the
dimensions of the relocated inlet, the dimensions of the sedimentation basin and the dimensions of the
dredging of Mason Creek. These scenarios are evaluated in terms of the tidal prisms, flow patterns in the
estuary and the velocities in the inlet. The recommended design (Model scenario 1) was selected based
upon consideration of "inlet cross-sectional and locational stability, total tidal prism, environmental
impacts (marsh impacts, changes in flushing, etc.), permitting constraints, maintenance requirements,
4
political achievability, and anticipated workability." These are very subjective criteria, and one could make
an argument than one or more of the other scenarios might be suitable as well. In fact, the supplement to
the EA presents at least one other scenario that might be considered acceptable.
The methodology used to develop and evaluate these scenarios is based upon sound engineering concepts.
The actual differences between them are often relatively small. Therefore, it seems reasonable that ATM
should meet with the various interested parties, reviewers and regulatory agencies and try to achieve a
consensus for the "Preferred Plan".
Plans for Dredged Material
The project calls for the placement of dredged material in the present inlet (to close it) and on the beaches
of Figure 8 Island. The dredging schedule will be designed to attempt to actually close the inlet in less than
72 hours. The overall plan and sequencing of activities appears reasonable.
The specifics of the volume of material to be dredged and the actual location where the material will be
placed on Figure 8 Island are presented in general terns. The EA does not present a detailed analysis of the
anticipated behavior of this beach nourishment, its life expectancy, probable redistribution or effectiveness
in adding protection to the property on the island. Of course, it is reasonable to assume that the placement
of 35 to 50 cubic yards of sand will be an improvement to the Figure 8 Island shoreline. However, given
the stated goal of using beach nourishment for storm protection, the EA might have presented a more
thorough analysis of this aspect of the project. There are a number of coastal engineering tools that would
enable ATM to model the behavior of the beach fill as it responds to the wave climate (including storms) at
the site.
Inlet Shoal Adjustments
The EA presents a general discussion as to how the existing ebb tide shoal will adjust and how the new
shoals will form and adjust at the new inlet location. This is a very qualitative description based upon
generally recognized ideas for inlet dynamics. There are no models for inlet mechanics suitable for design
at present. Engineers have to use experience and judgment to anticipate how the modified inlet will
behave. The history of the inlet morphology is often the best guide in this regard. The uncertainty of
storms and waves make these forecasts even more difficult. The discussion and predictions in the EA seem
reasonable. However, as noted several places in the EA, post-project monitoring, and a willingness to
make adjustments is critical to the overall success of this project.
Future Maintenance
The plan calls for a 1000 ft corridor for the new inlet. The EA states that it expects the inlet to remain
within this corridor for approximately 5 years. This assumption is based upon the overall analysis of the
site and its recent history. There is no way of knowing in advance if this is correct. If the current hurricane
climate (with a significant increase in both storm frequency and intensity) remains for the next several
years, than the 5 year assumption may prove to be optimistic. Again, one can only wait and watch. One
needs to be prepared to take action if the inlet begins to migrate out of this corridor sooner than the
assumed 5-year period.
5. Environmental Consequences
Tidal Hydraulics - See discussion of hydrodynamic model
Waves and Littoral Processes
The EA concludes that the new inlet location will result in a localized change in the wave refraction
pattems and a resultant change in the longshore transport of sediment. This is correct. These anticipated
changes are expected to be well within the range of the natural dynamics for an inlet and no adverse
impacts are expected as a result of these changes in the littoral processes.
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Shellfish ' and their va? &0 ` t `acf S is Chi ? ( /
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The EA discusses the potential environmental impacts of a proposed beach nourishment. This Still CS
presentation correctly states that any short-term impacts of placing sand on a beach are resolved relatively b5
quickly. Beach nourishment is a recognized coastal engineering procedure in North Carolina and its use
and impacts have been frequently studied. As long as the timing for nourishment is such that it does not
interfere with well known nesting periods, the potential adverse environmental impacts have been shown to
be minimal.
Cumulative Impacts
Due to the lack of an appropriate model for inlet dynamics, coupled with the fact that it is not possible to
predict the future wave and storm climate, it is not possible to exactly predict the changes in the project
after construction. The EA presents a reasonable forecast for what can be.expected to occur based upon the
history at the site and general coastal engineering principles. The need for periodic inlet maintenance is
certain. How often and what volumes are unknown. The 5-year interval speculated in the EA is probably
reasonable.
The EA speculates that the improved tidal flushing will result in an improvement in estuarine water quality.
While this conclusion is consistent with general ideas regarding the relationship between water quality and
flushing, the EA does not provide a detailed analysis to substantiate this claim. If potential water quality
improvements were important to the overall purpose of the proposed project, then additional water quality
modeling would seem justified.
Hydrodynamic Modeling of Mason Inlet and the Middle Sound Estuary
ATM - October 1999
Purpose
The hydrodynamic model was used in this study to determine the changes in tidal flows with the inlet
relocation, dredging of Mason Creek, and the dredging of the sedimentation basin. The model was used as
a tool to evaluate the various scenarios with-different dimensions. This is a reasonable methodology to
investigate this type of problem.
Hydrodynamic Model
The hydrodynamic model selected for this flushing analysis (WQMAP) is one of several currently being
used by the coastal engineering profession. The model is based upon a set of established physical
principles and computer algorithms. The model is two-dimensional with the flow averaged over the depth.
The use of a two-dimensional model for this study is appropriate. The assumptions regarding boundary
conditions are reasonable. The grid used to describe the project area is sufficiently dense to yield computed
results with a density acceptable for the desired analysis.
Model Calibration
All hydrodynamic models must first be calibrated before they can be used for design purposes. When
possible, this calibration should be done with field data collected at the study site. ATM collected tide and
current data adequate for this purpose. This conclusion is based upon the presented comparisons between
the model predicted water surface elevations and the recorded elevations (Figures 4-5 through 4-12). The
claim that "the model is successfully representing the tidal flow distribution in the system as a whole" is
justified.
As noted by a number of comments by the reviewing agencies, the Modeling Report does not present any
details of the sensitivity analysis for model parameters such as bottom friction (Manning n) and time step.
These issues are resolved satisfactorily in the Comments/Responses. It would have been preferable to
resolve these issues in the Modeling Report itself.
Model Application
Once the model was calibrated and shown to adequately reproduce the tidal hydraulics of the present
inlet/estuary system, ATM used it to model the flows for each of the alternative scenarios. Tidal prisms
and tidal (depth averaged) velocities were used to evaluate the different scenarios. Both spring and ebb
tides were modeled. Tables 5-2 and 5-3 summarize the results. ATM concludes that Scenario 1 is the
preferred alternative. This conclusion is somewhat speculative in that some of the differences between
scenarios are small, and probably beyond the actual ability of the hydrodynamic model to replicate what.
will actually occur should the scenario be constructed. Nonetheless, the choice of Scenario 1 is consistent
with the overall objectives of the proposed project.
Physical and Biological Monitoring Plan
ATM - October 1999
As noted previously in this review, a comprehensive monitoring program is essential to the overall success
of the project. The current ability of coastal engineers to predict the consequences of the proposed changes
in the inlet and adjacent estuary are limited. A monitoring program will facilitate intervention should it
become necessary to modify one or more aspects of the project.
The physical monitoring program proposed by ATM includes beach and offshore profiles, inlet bathymetry,
sediment sampling and aerial photography.
Beach and Offshore Profiles
The spatial density of the profiling program as currently proposed seems adequate. However, the proposed
schedule calls for profiles to be collected 6 months after the immediate post-construction surveys. I suggest
that it would be prudent to monitor the changes more frequently. Three or perhaps even 2 months after
construction would be a better interval to re-survey the project. In addition, the current plan calls for
annual surveys for only the first 2 years. given the fact that the EA makes it clear that this project will '
need periodic maintenance, plans should be made to undertake the surveys twice a year for as long as the
project is consider viable. In addition; there should be plans to continue to survey the project after severe
storms beyond the proposed 2-year limit.
Inlet Area Bathymetry
For the first two years of the project it would be better to survey the inlet twice a year as opposed to the
annual schedule proposed. In addition, the annual surveys should continue beyond the 2-year period
proposed.
This project site may be an excellent place for the Corps of Engineers to experiment with a relatively new
technology for using lasers to remotely map shallow water bathymetry. This new technology (SHOALS) is
scheduled to be evaluated by the Wilmington District of the Corps of Engineers. They should be
encouraged to explore the use of SHOALS at the project site.
Surficial Sand Sampling
The design of the sand sampling program is reasonable. The annual sampling program should be extended
beyond the proposed 2-year limit.
Aerial Photography
The use of controlled aerial photography will be an important element in the monitoring program. While
the ATM proposal would be useful, there are a number of things that could be done to improve the ultimate
utility of this photography. The photos should be collected with sufficient overlap that a proper rectified
digital model could be prepared. It may be appropriate to install permanent ground targets to facilitate this
process. The frequency of the photography should match the ground surveys with the proposed schedule
modifications. Most (if not all) of the photographic missions should be processed with the construction of
a digital elevation model (DEM) and a digital orthophotograph. The latter will be valuable tools when
concerns and or changes are discussed.
Additional Hydrodynamic and Flushing Model Scenarios
ATM - January 3, 2000
Six additional Scenarios were evaluated in this supplement. ATM seems to imply that Scenario 18 may be
another candidate for the preferred alternative. However, this is never formally stated in the report. This
needs to be clarified in the revised EA.
Comments/Responses
Note: unless otherwise stated, I consider the Response provided by ATM appropriate.
US Fish and Wildlife Service
December 22, 1999
In general the issues raised by the USFWS with regard to the hydrodynamic model would appear to place
far too much emphasis on the model which is only one part of the overall investigation. The ATM
modeling work appears to be more than adequate to answer the questions regarding tidal prisms and
flushing. Since water quality is not the primary focus of this design analysis, the modeling activities
described in the ATM reports seem reasonl&le. -However, many of the issues raised by the USFWS could
have been resolved if the original reports had provided greater detail.
Comment 5:
While it is not unusual to leave out the sensitivity analysis for parameters such as bottom roughness and
time step, the Modeling Report would have been more complete if these had been included. The ATM
response is nonetheless sufficient to answer these questions.
Comment 9:
While three-dimensional models are available, they would produce far more details of the flow field than
Age evaluate this project. C
Comment 15:
The ability of the model to reproduce storm induced flows for this inletlestuary system is marginal.. (? s°? X171
Comment 16:
The ATM response needs to be repeated. The hydrodynamic model cannot predict changes in the
morphology of the inlet. There are no models currently available that can make reliable predictions for
these systems. ATM's use of the past inlet history as a way to forecast future migration is reasonable.
However, it must be recognized that this empirical approach is limited and this is why the monitoring
program is an essential element of the project.
US EPA
January 3, 2000
Comment 1:
The EPA is correct, there is no sure way of knowing if the inlet will behave the way ATM has anticipated.
The ATM response does not clearly acknowledge this fact. However, the fact that we cannot know for sure
what will happen should not be a reason not to proceed if there is a reasonable, sound engineering rationale
for the project. As with all such projects, one needs to weigh the risks that the project will not perform as
planned with the benefits if it will. ATM has done a reasonable job in presenting these risks.
Comment 3:
The EPA's suggestion that more details should have been presented in the EA is appropriate. The ATM
response should be incorporated in the revised EA. This response is also a good explanation as to why the
alternative that does not include the dredging in Mason Creek is not likely to succeed. It is important to
recall that the fundamental philosophy of this project is to attempt toztslare the inlet and estuary to a
nat?at condition similar to what it was in the past when the inlet was more stabTF- TFe 1 Mason /J
Creek would a ear to have been an important element in this regard. LgA4I t ?dA ndf 0.
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Comment 5, part 3:,y i L J ('? /` y
l
ATM has not shown how it was determined that 1.5 ft/sec is the minimum flow needed to keep the channel
stable. A detailed discussion of this conclusion should be presented in the revised EA.
Comment 8:
This ATM study is clearly not intended to examine water quality. The suggestions that water quality will
be improved are highly speculative and probably should never have been raised in the EA. If water quality
issues are important, than water quality modeling needs to be undertaken ??1 a-6y ?'J jai Wilmington District, USACOE M(t
Technical Services Division ?r?5 n I
January 5, 2000 CJ?1 lP /
Comment 2: 1?J
The Corps' concern about the reversal of dominance from ebb to flood is not clearly answered by
ATM. The implication is that this change would adversely alter the morphology of the inlet. This should
be discussed in a revised EA.
Comment 3:
The Corps' request for an analysis of the flow throughout the entire modeled area has not been resolved by
the ATM response.
Comment 5:
The use of the O'Brien and Bruun method to analyze the inlet channel geometry is reasonable given that
none of these empirical inlet models are considered to be highly accurate. The request to use the Escoffer
Method could be easily added to the revised EA. Regardless of the method employed, it is not clear how
ATM decided that the desi the inlet should be 500 ft. A more detailed explanation of this would
Comment 6: _I
It is not clear if ATM is now suggesting that this Corps proposal, Scenario 18, is the new Preferred
Alternative.
Comment 9:
The ATM response should be incorporated in the revised EA. This response should be further amplified to
explain more clearly why ATM does not think the conditions that led to the high rates of inlet migration in
the mid 1980s will not be repeated after the inlet is relocated.
Comment 11:
There is no way of knowing in advance what the actual volumes of sediment trapped in the new ebb tidal
shoal will be. The ATM estimates are based upon a reasonable analysis of the system. This is why the
monitoring program is an important element in the project.
Comment 12:
The development of the proposed Mason Inlet Management Plan should be a requirement for this project.
Wilmington District, USACOE
Regulatory Division
January 5, 2000
I have no additional input to the ATM respionses'to these comments.
US Fish and Wildlife Service
January 7, 2000
Comment 1: Measures to Prevent Project Failure During Inlet Closure
I do not understand what "Project Failure" means. The ATM construction plans for closing the inlet seem
reasonable. The stated intention of having careful construction supervision during the closing will help to
prevent a failure of inlet closing.
Comment 2:
The USFWS concern about the maintenance dredging required in the future is a valid concern. The ATM
estimate that it will be 5 years before this dredging is needed (as pointed out in the ATM response) is based
upon a number of assumptions. One or more of these assumptions may prove to be false, and therefore the
need for the monitoring program is well founded. All of the parties involved in this project need to
recognize that there is a real potential for inlet dredging to be required before the 5 years have elapsed.
10
Comment 3:
It is not clear what the USFWS means by "less environmentally damaging alternative."
Comment 9:
The USFWS suggests that if left to its own devices the migrating inlet and subsequent erosion of the north
end of Wrightsville Beach will result in a natural barrier island with all of the structures eventually lost.
Perhaps, but over what time frame? tizens of New Hanover County be prepared to deal
with the loss of the structures and the s In the meantime, while all of this is taking place,
what will be the impacts on, the na en ' ? This is an old debate, and it does not seem
particularly relevant to the present evaluation o the proposed project.

National Marine Fisheries
Environmental Assessment
January 2000
Comment 4:
ATM's assertion that the increase in flushing in the estuary will lead to an improvement in water quality is
probably correct. However, as noted by a number of reviewers, there has been no water quality modeling
of the proposed project. Given the nature of the project, there is no reason to assume that this increase in
flushing will cause any adverse water quality impacts unless the suggested increase in salinity is considered
to be an adverse impact. As stated elsewhere, if water quality is a concern, then water quality modeling
needs to be undertaken.
Comment 6:
Given that there will be sand available to nourish the beaches on Figure 8 Island, there is no engineering
rationale for not including beach nourishment as a part of the inlet relocation.
Comment 7:
The NW is correct in stating that periodic dredging of the relocated inlet will be required. The concern
that this activity will interfere with the migration of fish through the inlet is an important issue in coastal
engineering design today. This project would seem to be an excellent opportunity to study this problem
through biological monitoring during dredging and non-dredging periods.
National Marine Fisheries
Project Design and Environmental Impacts
January 2000
Comment 11:
The NMF notes that the hydrodynamic model used to evaluate the flushing and changes in tidal prism does
not specifically evaluate water quality. This is correct. If there is sufficient concern regarding the water
quality impacts of the proposed project then it would be appropriate to undertake a formal water quality
analysis. This additional modeling activity could be readily added to the existing hydrodynamic model.
11
Re: Mason Inlet
Subject: Re: Mason Inlet
Date: Mon, 31 Jul 2000 12:45:51 -0400
From: Milt Rhodes <[e-mail]>
Organization: NCDENR-Division of Water Quality, Local Government Assistance Unit
To: Cyndi Karoly <[e-mail]>
Eric Fleek provided some comments on the project several weeks ago. They
are a long way from being through. Please do not issue anything yet. John
is aware of the situation. I will speak with Melba McGee about the status
of the project, but we had some issues that needed to be addressed before
the SEPA process was completed. Again, Eric and/or John know best as to
what the issues are.
Thanks for letting me know.
Milt
Cyndi Karoly wrote:
> Milt, we have a CAMA application for the Mason Inlet Relocation project
> sponsored by New Hanover County. I noticed a note in the file saying
> this project is in the SEPA process. Do you know where it is in the
> process at this time? Please let me know if I need to get more info to
> you.
> Thanks. CK.
Community Planner
North Carolina Department of Environment and Natural Resources, Division of Water Quality
Local Government Assistance Unit
1 of 1 7/31/00 1:38 PM
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North Carolina Department of Environment,
Health, and Natural Resources eo Printed on Recycled Paper
MEMORANDUM
TO: John Dorney Regional Contact: J. Steenhuis
Non-Discharge Branch WO Supervisor: Bick Shiver
Date:
SUBJECT: WETLAND STAFF REPORT AND RECOMMENDATIONS
Facility Name New Hanover Countv Mason Inlet Relocation
Project Number 00 0008
Recvd From DCM
Received Date 1/4/00 Recvd By Region
Project Type New inlet
County New Hanover
County2
Region Wilmington
0_1\
Certificates Stream Stream Impacts (ft,)
Permit Wetland Wetland Wetland Stream Class Acres Feet
Type Type Impact Score Index Prim. Supp. Basin Req. Req.
CAMA SM O Y O N F- 18-87-24-3 SA ORW 30,624. 2.90 F_ F_-
F_F__OY ON ??????? F F_
Mitigation Wetland
MitigationType Type Acres Feet
Is Wetland Rating Sheet Attached? O Y ON Did you request more info? O Y ON
Have Project Changes/Conditions Been Discussed With Applicant? O Y O N
Is Mitigation required? O Y O N
Provided by Region: Latitude (ddmmss) 341440
Recommendation: O Issue * Issue/Cond O Deny
Longitude (ddmmss) 774618
Comments:
This office agrees in particular with one major condition outlined in the NC Wildlife Resources letter
dated 5_31-60 The letter would Ijke the dredgjng of banks channel behjnd Figure 8 to stop. Thjs
office highly supports this condition due to the potentjal of stabiljzing the inlet somewhat jf thjs were
clone. This office is also concerned about the turbidjty that may be caused by thjs eject and would
limjt jt to 25 NTU in waters outside the project area. The mjtigatjon for any wetlands also needs to be
worked out to the satisfaction of water quL ljty.
cc: Regional Office
Page Number
Central Office 1
Facility Name' New Hanover County Mason Inlet Relocation County New Hanover
Project Number 00 0008 Regional Contact: J. Steenhuis
Date: 7/25/2000
Comments (continued from page 1):
cc: Regional Office
. Central Office Page Number 2