20200622 Ver 1_EA_Project 14-0029_20200730

REPLY TO
AT I FN I ION 01'
DEPARTMENT OF THE ARMY
WILMINGTON DISTRICT, CORPS OF ENGINEERS
69 DARLINGTON AVENUE
WILMINGTON, NORTH CAROLINA 28403-1343
JUL 17 2013
. ,.;
Planning and Environmental Branch �, •:,� ;, � t �,
'\ Jut 2013
Ms. Crystal Best
N.C. Dept of Administration — State Clearinghouse LCi
1301 Mail Service Center cDQA
f�'
Post Office Box 1000
Raleigh, North Carolina 27699-1301
Dear Ms. Best:
Enclosed are 16 copies (2 hard copies, 14 CDs) of the Environmental Assessment (EA)
addressing the refinement in utilization of borrow areas located offshore of Topsail Island for the
purpose of Coastal Storm Damage Reduction (CSDR) at Topsail, Surf City, and North Topsail
beaches. The document is also available on the Wilmington District's website at
llttp://www,saW.Lisace.anny.inil/Library/Pi-oiects.aspx . This EA supplements the Environmental Impact
Statements (EISs) prepared in 2009 and 2010 and contained within the following reports:
• U.S. Army Corps of Engineers, 2009. Final Integrated General Reevaluation Report and
Environmental Impact Statement, Shore Protection, West Onslow Beach and New River
Inlet (Topsail Beach), NC. February 2009.
US. Army Corps of Engineers. 2010. Final Integrated ],'easibility Report and
Environmental Impact Statement, Coastal Storm Damage Reduction, Surf City and North
Topsail Beach, North Carolina, December 2010.
Initial study phase geotechnical investigations identified sufficient sediment to meet the 50
year needs of both projects. In accordance with environmental commitments made for both
projects, more complete geotechnical investigations of the borrow areas have since been
conducted during the Planning, Engineering, and Design (PED) phase of the projects and
detailed borrow area dredging plans have been completed. The additional PED analyses resulted
in a refinement in the borrow area characterizations and a change in the borrow area utilization.
Specifically, the inclusion of these additional data sets in the compatibility analyses resulted in a
slightly higher amount of fine-grained and granular material than allowed under the North
Carolina state compatibility standards (15A NCAC 07H .0312, Technical Standards for Beach
Fill Projects) when comparing certain borrow areas to the native beach.
The refined borrow area characterization and utilization will not result in significant beach
compatibility concerns and/or impact biological resources to a level of significance beyond what
was previously evaluated in the referenced EISs for both projects. The EA has been prepared in
accordance with the Council on Environmental Quality and the U.S. Army Corps of Engineers'

regulations for implementing the National Environmental Policy Act of 1969 (33 CFR 230), as
amended.
Based on the information contained in the EA, we believe that the proposed action will not
significantly affect the quality of the human environment and that an Environmental Impact
Statement will not be prepared. However, we will make our final determination after we have
reviewed the comments that have been received from the public and other agencies.
We would appreciate receiving any comments regarding our determination within 30 days of
the date of this letter. If you have any questions regarding this matter, please contact Mr. Doug
Piatkowski, U.S. Army Corps of Engineers, Wilmington District, 69 Darlington Avenue,
Wilmington, NC 28403, E-Mail: [e-mail]., telephone: (910) 251-
4908.
Sincerely,
Elden Gatwood
Chief, Planning and Environmental Branch
Enclosures

II ^ JUL 2013
US Army Corps o NED �
of Engineers 'W
WILMINGTON DISTRICT
F9 f 7,
ENVIRONMENTAL ASSESSMENT
West Onslow Beach and New River Inlet (Topsail Beach)
and
Surf City and North Topsail Beach
Coastal Storm Damage Reduction Projects
Pender and Onslow Counties, North Carolina
July 2013

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Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
Executive Summary
Project Area/Background. Topsail Island is a 26-mile long barrier island located in
Pender and Onslow counties, NC. From south to north, the three communities on the
island are the Towns of Topsail Beach, Surf City, and North Topsail Beach. In
accordance with Congressional study authorizations, Coastal Storm Damage Reduction
(CSDR) opportunities were evaluated for the entire island. A CSDR project for Topsail
Beach was originally authorized as the West Onslow Beach and New River Inlet (Topsail
Beach) project; a Post -Authorization Change (PAC) repot (a General Reevaluation
Report (GRR)) recommended a modification to the project as originally authorized. This
modified project is near the end of the design phase of work and is currently awaiting re-
authorization and appropriation of construction funds. A Feasibility Study for the Surf
City and North Topsail Beach (SCNTB) CSDR project has been completed and the
design effort for this project is also underway while awaiting authorization and
appropriation of construction funds.
The recommended plan for Topsail Beach is a dune (12 ft above National Geodetic
Vertical Datum 29 (NGVD 29)) and berm (50 ft wide at 7 ft above NGVD 29) extending
along approximately 26,200 ft of shoreline. The total required sediment volume for
initial construction and nourishment events spanning the 50 year project life is
approximately 13.6 Million Cubic Yards (MCY). The recommended plan for SCNTB
consists of a dune (15 ft above NGVD) and berm (50 ft wide at 7 ft above NGVD 29)
extending along approximately 52,150 ft of shoreline. The total required sediment
volume for initial construction and nourishment events over the 50 year project life is
approximately 32.3 MCY.
Initial subsurface investigations were performed during feasibility phase analysis of both
the Topsail Beach and SCNTB projects and included a total of 358 borings located
offshore of Topsail Island, in Banks Channel behind the town of Topsail Beach, in the
connecting channel between the Atlantic Intracoastal Waterway (AIWW) and New
Topsail Inlet, and in New Topsail Inlet. A combination of boring data and geophysical
surveys were used to identify and define borrow areas for both projects. Based on these
initial Study phase investigations, a sufficient volume of compatible material was
identified within 16 borrow areas located between 1-5 miles offshore of Topsail Island to
meet the 50 year volume requirements for both projects. Compatibility evaluations at the
time were completed in accordance with both the pending North Carolina state sediment
compatibility standard as well as the Wilmington District's sediment compatibility
practice.
During the Study phase of both projects, the North Carolina Coastal Resources
Commission (NCRC) was concurrently developing new sediment compatibility standards
for sediment placed on the beach in association with dredging for beach nourishment and
navigation projects. As a component of their final consistency concurrence letter for the

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Topsail Beach CSDR project (dated 7 November 2006), the North Carolina Division of
Coastal Management (NCDCM) stated the following:
"The Corps should be advised that the NCCRC is currently developing new sediment
compatibility standards. Once these new standards are passed by the NCCRC, and
assuming these standards are approved by Office of Ocean and Coastal Resource
Management (OCRM) as a federally approved component of the State's coastal
management program, these new standards will apply to future beach nourishment
projects from that point forward. The Corps is strongly encouraged to closely follow the
development of these new standards. The Corps should also incorporate any such
standards into the planning process for the proposed project. "
The Corps considered the State's new sediment compatibility standards for both projects
and was advised by NCDCM at the time that the development of these detailed
compatibility standards would not further constrain sediment availability for the projects
beyond the Wilmington District's existing compatibility practices. Though the new State
sediment compatibility standards have since been passed by the NCCRC (15A NCAC
07H .0312, Technical Standards for Beach Fill Projects), to date they have not beef)
submitted to the National Oceanic and Atmospheric Administration's (NOAA's) OCRM
for consideration as a federally approved component of the State's coastal management
program. In the absence of this OCRM approval, the State sediment compatibility
standards are not required as a component of the Federal consistency determination in
accordance with the Coastal Zone Management Act (CZMA) of 1972.
Both Topsail Island projects are currently in the Pre -construction Engineering and Design
(PED) phase of work. PED products include preliminary project plans as well as detailed
borrow area dredging plans, which usually require a more detailed geotechnical dataset
than that collected for feasibility level analyses. Consequently, additional geotechnical
investigations of the offshore borrow areas were conducted on a finer sampling grid to
support the development of detailed borrow area dredging plans. Although the
Feasibility/GRR Study phase geotechnical investigations appeared to indicate that
sufficient material was available to meet the 50 year project life requirements for both
projects, the additional analyses conducted during PED resulted in a refinement of the
borrow area characterizations and a change in the borrow area utilization. Specifically,
the inclusion of these additional data sets in the compatibility analyses resulted in a
slightly higher amount of fine-grained material, but less than 10% by weight based on the
Wilmington District practice, and more granular material than allowed under the State
standards within certain borrow areas. The State compatibility standards limit the
amount of fine-grained and granular material not to exceed more than 5% over the native
beach. As the native beach has been heavily washed, the amount of fine-grained material
is approximately I % and the amount of granular material is less than 5%.
Utilization of the borrow areas as identified during the PED geotechnical investigations
and application of the Wilmington District's compatibility practice for beach placement

Environmental Assessment
West Onslow Beach and New River Inlet (Tolmid Beach) and Su f Citp and North
Tolrsail Beach Coastal Storm Damage Reduclion Projects
of sediment is the proposed action of this Environmental Assessment (EA). Although the
increased amount of fine-grained sediment identified during PED investigations in certain
portions of the borrow areas is higher than the State's sediment compatibility standard
allows, use of this material in aggregate would not result in significant beach
compatibility concerns and/or impact biological resources to a level of significance
beyond what was previously evaluated in the Environmental Impact Statements (EISs)
for both projects. Prior to the establishment of the State standard, the Wilmington
District successfully constructed multiple CSDR and navigation disposal projects
throughout North Carolina utilizing a compatibility threshold of <10% fine-grained
sediment passing the #200 sieve. All of the borrow areas located offshore of Topsail
Island are considered compatible with respect to this Wilmington District practice.
Isolated portions of two borrow areas contain higher granular material than specified in
the State standards. The Wilmington District compatibility practice does not specifically
evaluate granular material; however, prior to dredging these borrow areas, mitigative
efforts will be implemented to avoid and/or screen the material from being placed on the
beach. Implementation of the Wilmington District compatibility practice coupled with
the mitigation measures to avoid placement of granular material on the beach would
result in sufficient borrow area volume for the life of both projects while avoiding
adverse impacts to biological resources.
Proposed Action. The proposed action (preferred alternative) is to utilize PIED
geotechnical data for Topsail Beach and SCNTB CSDR project offshore borrow areas
and implement a borrow area utilization plan which relies upon the application of the
Wilmington District's compatibility practice for beach placement of sediment. The
proposed action would maintain the current borrow area acreage impacts evaluated in the
Topsail Beach and SCNTB EISs and avoid the impacts associated with additional
offshore investigations for borrow areas and actual dredging and conveyance of sediment
from those sites.
This EA evaluates resources in the project area for potential impacts from the proposed
action, as well as the no action alternative. Specific resource categories with the potential
to be affected by the proposed action include: Water Quality, Swrf Zone Fishes, Benthic
Resources — Surf Zone, Benthic Resources — Nearshore Ocean, Essential Fish l Iabitat
(Hard Bottoms), Endangered and Threatened Species, Recreational and Aesthetic
Resources. This EA determined that, while short term, temporary, and minor impacts
would be imposed on several resource areas under the proposed action; there would be no
significant adverse impacts.
The proposed action should not significantly affect the quality of the human environment;
therefore, an Environmental Impact Statement (EIS) will not be required. If this opinion
is upheld following circulation of this EA, a Finding of No Significant Impact (FONSI)
will be signed and circulated.

F.nviromnental Assessment
Wesi Onslou, Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
TABLE OF CONTENTS
Section
Page
ExecutiveSummary.......................................................................................................... ii
Acronymsand
Abbreviations.......................................................................................viii
1.0
Introductiorr...........................................................................................................
1
1.1
Incorporation by Reference.....................................................................................
1
1.2
Authorizing Legislation..........................................................................................1
1.3
Background.............................................................................................................2
1.4
North Carolina Sediment Compatibility Standards - Summary .............................
3
1.5
Wilmington District Compatibility Practice - Summary ........................................
4
1.6
Compatibility Differences — Study Phase vs. PED Phase
Investigations..........................................................................................................
5
1.7
Comparison of the Application of the NC Sediment Criteria and the
Wilmington District Compatibility Practice for the Topsail and
SCNTBBorrow Areas............................................................................................
6
1.8
Commitments for Borrow Area or Sediment Management ..................................
13
2.0
Put -pose and Need for the Proposed Project ....................................................
15
3.0
Alternatives..........................................................................................................15
3.1
Proposed Action - Wilmington District Compatibility Practice
(Preferred Alternative)..........................................................................................
15
3.2
No Action..............................................................................................................
16
4.0
Affected Environment and Environmental Consequences .............................
16
4.1
Surf Zone Fishes...................................................................................................
17
4.2
Benthic Resources — Surf zone.............................................................................
18
4.3
Benthic Resources—Nearshore Ocean.................................................................
19
4.4
Essential Fish Habitat...........................................................................................
19
4.5
Endangered and Threatened Species....................................................................
20
4.6
Recreation and Aesthetic Resources.....................................................................
21
4.7
Environmental Impact Comparison of Alternatives.............................................22
4.8
Unavoidable Adverse Impacts of the Proposed Action ........................................
25
v

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
4.9 Cumulative Impacts.............................................................................................. 25
5.0 Compliance with Environmental Requirements .............................................. 25
5.1 North Carolina Coastal Management Program ...................................................... 25
6.0 Agency and Public Involvement........................................................................ 27
7.0 Point of Contact................................................................................................... 29
8.0 Finding............................................................................................................30
9.0 Preparers............................................................................................................. 31
10.0 References............................................................................................................32

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Sraf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
LIST OF TABLES
Table page
Table 1. Borrow area evaluation for the Study and PED phases ....................................... 5
Table 2. Mean sampling data from the native beach and Borrow Area A for
the Topsail Beach CSDR project. (* the State criteria do not consider the %
passingthe #200 sieve)..................................................................................................... 1 I
Table 3. Mean sampling data from the native beach and borrow areas for the
SCNTB CSDR project. (* the State criteria do not consider the % passing the
#200 sieve)....................................................................................................................... 1 I
Table 4. Summary and comparison of impacts to each resource category
relative to the preferred and no action alternatives........................................................... 22
LIST OF FIGURES
Fi2ui-es
Page
Figure I. Borrow source for West Onslow Beach and New River Inlet
(Topsail Beach) CSDR project. (*Green line denotes boring locations
referenced in the fence diagram identified in Figure 2)...................................................... 7
Figure 2. Example fence diagram showing a comparison of the selected
material usable depths using the State compatibility standard and the
Wilmington District (SAW) compatibility practice. (Note: In this diagram,
material between the blue and orange lines would be unavailable using the
State compatibility standard, but beach compatible based upon the SAW
compatibilitypractice)........................................................................................................ 8
Figure 3. Borrow sources for the SCNTB CSDR project ................................................. 12
LIST OF APPENDICES
Appendix
A West Onslow Beach and New River Inlet (Topsail Beach) and Surf
City and North Topsail Beach Coastal Storm Damage Reduction
Projects - A Summary of Report Sections Referencing the North
Carolina State Sediment Compatibility Standards

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Acronyms and Abbreviations
ACES
Automated Coastal Engineering System
AIWW
Atlantic Intracoastal Waterway
BA
Biological Assessment
CSDR
Coastal Storm Damage Reduction
CEQ
Council of Environmental Quality
CFR
Code of Federal Regulations
CZMA
Coastal Zone Management Act
ESA
Endangered Species Act
EA
Environmental Assessment
EIS
Environmental Impact Statement
EPA
U.S. Environmental Protection Agency
ER
Army Engineer Regulation
EM
Engineering Manual
FEMA
Federal Emergency Management Agency
FWCA
Fish and Wildlife Coordination Act
FONSI
Finding of No Significant Impact
GRR
General Reevaluation Report
HAPC
Habitat Areas of Particular Concern
MCY
Million Cubic Yards
MSFCMA
Magnuson -Stevens Fishery Conservation and Management Act
NEPA
National Environmental Policy Act of 1969, as amended
NGVD
National Geodetic Vertical Datum
NC
North Carolina
NCCRC
North Carolina Coastal Resources Commission
NCDCM
North Carolina Division of Coastal Management
NOAA
National Oceanic and Atmospheric Administration
NTU
Nephelometric Turbidity Units
OCRM
Ocean and Coastal Resource Management

Environmental Assessment
Wes? Onshnv Beach and Neiv River Inlet (Topsail Beach) and Sur( City and North
Topsail Beach Coastal Storm Damage Reduction Projects
PAC
Post -Authorization Change
PCA
Project Cooperation Agreement
PED
Preconstruction Engineering and Design
PDT
Project Delivery Team
ROD
Record of Decision
SAW
South Atlantic Division, Wilmington District
SCNTB
Surf City and North Topsail Beach
USACE
U.S. Army Corps of Engineers
WRDA
Water Resources Development Act

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Environmental Assessment
West Onslou, Beach and Ncu, River Inlet ('Topsail Beach) and Smf Cily and North
Topsail Beach Coastal Slorm Damage Reduction Projects
1.0 Introduction
1.1 Incorporation by Reference
Specific details for both the West Onslow Beach and New River Inlet (Topsail Beach),
North Carolina (NC) and Surf City and North Topsail Beach (SCNTB) Coastal Storm
Damage Reduction (CSDR) projects are provided in the following integrated reports:
• U.S. Army Corps of Engineers, 2009. Final Integrated General Reevaluation
Report and Environmental Impact Statement, Shore Protection, West Onslou,
Beach andNeu, River Inlet (Topsail Beach), NC. February 2009.
• U.S. Army Corps of Engineers. 2010. Final Integrated Feasibility Report and
Environmental Impact Statement, Coastal Storm Damage Reduction, Szof City
and North Topsail Beach, North Carolina. December 2010.
These two reports contain extensive background information pertaining to project related
environmental impacts in accordance with the National Environmental Policy Act
(NEPA) of 1969, as amended. This EA will include additional information and analyses
that will supplement the referenced EISs for both projects with respect to refinements in
borrow area utilization; however it will not repeat the detailed information within the
EISs incorporated herein by reference. Specific sections from the referenced reports for
both projects containing relevant sediment compatibility statements and/or discussions
are included in Appendix A.
1.2 Authorizing Legislation
Topsail Beach Coastal Storm Damage Reduction (CSDR) Project. Section 101 of the
Water Resources Development Act (WRDA) of 1992 authorized the construction or
implementation of the original West Onslow Beach and New River Inlet (Topsail Beach)
Shore Protection Project at Topsail Beach, Pender County, North Carolina. However, the
Project Cooperation Agreement (PCA) was not executed and the project was then placed
in an inactive status. Following multiple storm events, the project was reactivated in
2000 at the request of the Town of Topsail Beach.
The Energy and Water Development Appropriations Act for Fiscal Year 2001, Public
Law 106-377, included funds for the Government to initiate a General Reevaluation
Report (GRR) of the authorized West Onslow Beach and New River Inlet (Topsail
Beach) Shore Protection Project. A Chiefs Report and Record of Decision (ROD) were
signed on 28 September 2009 and 23 April 2010 for Topsail Beach, respectively. As the
project recommended in the GRR extends the boundaries of the currently authorized
project, this updated project requires re -authorization subsequent to appropriation of
construction funds.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Surf City North Topsail Beach (SCNTB) Coastal Storm Damage Reduction (CSDR)
Project. Study authorization for the SCNTB Feasibility Study was contained in two
Congressional resolutions (one for Surf City and one for North Topsail Beach, NC)
adopted February 16, 2000, and April 11, 2000. A Chiefs Report and ROD
accompanying the Final SCNTB Feasibility Report were signed on 30 December 2010
and 13 April 2011 for SCNTB, respectively. The project is currently in the Pre -
construction, Engineering, and Design (PED) phase of work while awaiting authorization
and appropriation of construction funds.
1.3 Background
The recommended CSDR plan for Topsail Beach consists of a sand dune constructed to
an elevation of 12 ft above the NGVD 29, fronted by a 50 ft wide beach berm constructed
to an elevation of 7 ft above NGVD 29. This dune and berm feature would extend
23,200 ft, with a 2,000 ft northern transition fill, and a 1,000 ft southern transition fill, for
a total length of 26,200 ft. The total required sediment volume for initial construction
and nourishment events throughout the 50 year project life is approximately 13.6 MCY.
The plan contained in the GRR identified a total of five offshore borrow areas with
sufficient compatible sediment to support initial construction and each nourishment event
for the 50 year life of the project.
The recommended plan for SCNTB consists of a sand dune constructed to an elevation of
15 ft above the NGVD 29 fronted by a 50 ft-wide beach berm constructed to an elevation
of 7 ft above NGVD 29. The berm and dune project extends along a reach of 52,150 ft.
The total required sediment volume for initial construction and nourishment events
throughout the 50 year project life is approximately 32.3 MCY. The plan contained
within the Feasibility Report identified a total of 16 borrow areas offshore of Topsail
Island, including excess material from the borrow areas identified for the Topsail Beach
project, with sufficient compatible sediment to support initial construction and each
nourishment event for the 50 year life of the project
Initial subsurface investigations were performed during both the Topsail Beach and
SCNTB Study phases and included a total of 358 borings located offshore of Topsail
Island, in the Banks Channel behind the town of Topsail Beach, in the connecting
channel between the Atlantic Intracoastal Waterway (AIWW) and New Topsail Inlet, and
in New Topsail Inlet. A combination of data from the borings and the geophysical
surveys were used to identify and define borrow areas for both projects. Based on these
initial investigations, sufficient compatible material was identified to meet the 50 year
volume requirements for both projects; however, both reports stated that additional
vibracores (500-1,000 ft. spacing) and/or geophysical surveys would be collected during
PED to better delineate the borrow area boundaries and material types and support the
development of a detailed dredge plan.
The State compatibility standards and the Wilmington District compatibility practice
were both evaluated when assessing total borrow area volumes available during the Study

Fnvironmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
phase for both projects. Based on the feasibility -level data collected within each borrow
area, a sufficient amount of compatible material was identified to meet the 50 year
volume needs for both projects while considering the State standards and the Wilmington
District compatibility practice. Therefore, the Corps documented in the reports for both
projects the intent to adhere to the State compatibility standards. References to sediment
compatibility were made in the project report documents as a component of the NEPA
documentation, Fish and Wildlife Coordination Act (EWCA) recommendations, and the
Section 7 Endangered Species Act (ESA) Biological Assessment (BA) (Appendix A).
However, both reports clearly stated that more refined geotechnical investigations of the
borrow areas would be completed during the PED phase of both projects.
PED level investigations were subsequently completed in 2010 within borrow area A for
the Topsail Beach project and in 2011 for the SCNTB project within borrow areas G, H,
J, L, O, and P. During PED investigations, the Corps conducted additional geophysical
surveys, additional vibracore borings, and completed borrow compatibility analyses in
accordance with both the Wilmington compatibility practice and the State compatibility
standards. The additional analyses resulted in a refinement in the borrow area
characterizations and a change in the borrow area utilization to meet dredge plan
requirements. Specifically, the inclusion of these additional data sets in the borrow area
compatibility analyses resulted in the identification of a slightly higher percentage of
fine-grained and granular material in portions of the borrow areas compared to the native
beach. Considering the low percentages of fine-grained material on the native beach, the
slight increase in fine-grained sediment within certain borrow areas exceeded the
percentage allowed under the State standard.
The refinement of the borrow area characterization and use plans during PED analyses
indicated that, using the State's sediment compatibility standards, there would be
insufficient sediment volumes to support the 50 year life of both projects. When using
the Wilmington District practice for assessing compatibility, there is sufficient borrow
area volume for the life of the projects. The incremental change in sediment
characteristics following PED data collection would not incur additional adverse impacts
beyond the impact threshold evaluated in the original EISs, while providing the sediment
volume needed for the 50 year project life. Therefore, the proposed action is to utilize the
borrow areas as identified during the PED investigations for the Topsail Beach and
SCTNB CSDR projects and apply the Wilmington District's compatibility practice for
beach placement of sediment
1.4 North Carolina Sediment Compatibility Standards- Summary
In 2007, the State of North Carolina implemented 15A NCAC 07H.0312 to govern
sediment compatibility for beach nourishment projects; however, these new standards
have not yet been submitted to the National Oceanic and Atmospheric Administration
(NOAA) office of Ocean and Coastal Resource Management (OCRM) for consideration
as a federally approved component of the State's coastal management program. In the

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf Cry and North
Topsail Beach Coastal Storm Damage Reduction Projects
absence of this OCRM approval, the NC sediment compatibility standards are not
required as a component of the Federal consistency determination in accordance with the
Coastal Zone Management Act (CZMA) of 1972. Relevant sections of 15A
NCAC 07H.0312 for the purpose of this EA are as follows:
• "The average percentage by weight offine-grained sediment (less than
0.0625 mm) in each borrow site shall not exceed the average percentage by
weight of fine-grained sediment of the recipient beach characterization plus five
(5) percent"
• "The average percentage by weight of calcium carbonate (shell) in a borrow site
shall not exceed the average percentage by weight of calcium carbonate of the
recipient beach characterization plus 15 percent"
• "The average percentage by weight of granular sedinient in a borrow site shall
not exceed the average percentage by weight of coarse -sand sediment of the
recipient beach characterization plus five (5) percent. "
1.5 Wilmington District Compatibility Practice - Summary
The Wilmington District has historically met the intent of the State sediment
compatibility standards through diligent best professional judgment practices coupled
with detailed sediment compatibility analyses, which evaluate the grain size
characteristics of the material within the potential borrow area. In order to assure that
beach placement material consists predominately of sand, the Wilmington District
compatibility practice requires that the borrow area contains sediment with an average
weighted fine-grained material content of less than (<) 10%passing the #200 sieve. In
addition to grain size analyses, selection of material for beach placement is also
determined by evaluating cross sections of the sediment within the proposed borrow area
to assure that areas containing incompatible sediment overlying compatible sand are
removed from the detailed borrow area dredge plan. These guidelines have historically
been utilized by the Wilmington District to assure compatibility for CSDR projects (i.e.
Wrightsville, Carolina, Kure, and Ocean Isle beaches) with much success and continue to
be used for beach placement of dredged material from navigation channels.
The Wilmington District compatibility practice of <10% fine-grained material passing the
#200 sieve is also reflected in the State compatibility standards which allow up to 10%
fine-grained material to be placed on the beach in association with dredging navigation
maintenance material. Specifically, the rule states the following:
"Sediment completely confined to the permitted dredge depth of a federally or state
maintained navigation channel shall be considered compatible if the average percentage
by weight offrne-grained (less than 0.0625 millimeters) sediment is less than 10 percent"

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Staf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
1.6 Compatibility Differences - Study Phase vs. PED Phase Investigations
Realizing the coarse sampling grid (5,000 ft spacing) used to collect borrow area boring
data during Study phase investigations for both projects, it was noted in both the Topsail
Beach and SCNTB reports that additional borings and/or geophysical surveys would be
performed during PED to better delineate the borrow area boundaries and characterize
material types.
These detailed geotechnical and geophysical investigations of the borrow areas were
completed during the PED phase of both projects in 2010 and 2011. Specifically, borings
were conducted using 1,000 ft spacing within borrow area A for the Topsail Beach
project and borrow areas G, H, J, L, O, and P for the SCNTB project in order to further
define borrow area characteristics in support of dredge plan development. These more
detailed PED analyses identified slightly higher amounts of fine-grained and granular
material within portions of a few borrow areas. Table I provides a summary of the
borrow area analysis in comparison to the native beach material during the Feasibility
Study phase and the PED phase. It is shown in Table I that borrow areas A, H, O, and P
have finer mean grain size material based on the PED analysis than that of the Study
analysis. In addition, borrow areas J and L contain slightly more granular material from
the PED analysis than that of the Study analysis.
Table I. Borrow area evaluation for the Study and PED phases.
Study Phase
PED Phase
Borrow Area
Mean
(phi)
Mean
mm
Weight %
Fines
(passing
#230 t
Weight%
Passing
#102
Mean
hi
Mean
mm
Weight %
Fines
(passing
#230)3
Weight%
Passing
#102
Topsail Native
Beach
2.15
0.23
1.0
- 3
2.15
0.23
1.0
99.0
A
2.36
0.20
6.6
97.8
2.61
0.16
7.5
96.3
SCNTB Native
Beach
1 2.15
0.23
1.2
98.4
2.15
1 0.23
1.3
98.1
G
2.05
0.24
5.2
92.1
2.17
0.22
5.1
94.8
H
2.21
0.22
2.6
96.4
2.48
0.18
3.2
98.8
J
2.12
0.23
4.5
96.6
1.92
0.26
3.8
92.7
L
2.05
0.24
6.3
94.1
1.57
0.34
4.8
87.9
0
2.12
0.28
6.2
93.3
2.22
0.21
6.4
95.1
P
2.01
0.25
5.5 1
91.0
2.32
0.2
8.3
96.4
' The #230 sieve = 0.063 min / 4.0 phi. The # 10 sieve = 2.0 min / -1.0 phi.
3 The materials retained on the # 10 or larger sieves are considered "granular" material.
' The granular material was not evaluated during the Study phase for Topsail.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
1.7 Comparison of the Application of the NC Sediment Criteria and the
Wilmington District Compatibility Practice for the Topsail and SCNTB Borrow
Areas
A compatibility analysis for a CSDR project relies on the laboratory analysis of the
sediment grain size and calcium carbonate content for the borrow area. For both the
Topsail and SCNTB projects, samples of subsurface sediment from vibracores were used
to define these material characteristics. Each boring and corresponding laboratory tested
samples were compared to the composite native beach characteristics for grain size and
calcium carbonate. Figure I shows the location of the borings diagrammed in Figure 2;
these borings are marked with a green line. A fence diagram is provided in Figure 2 to
show borrow area evaluation comparing State compatibility standards and Wilmington
District compatibility practice. After the individual vibraeore boring evaluations were
complete, the borrow area was composited to determine the overall compatibility of the
borrow area. In the case of borrow area A, the composite compatibility analysis using the
Wilmington District compatibility practice allowed for the use of material which was
slightly more fine-grained than that allowed by the state criteria. This is the result of the
native beaches containing such low amounts of fine-grained material (in some cases less
than 1%) that beach compatible material containing 6 to 10 percent fine-grained material
would not have been available for use under the State compatibility standards.

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Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Table 2 and Table 3 show the composite native beach data and the composite data for
borrow areas identified for use for both the Topsail Beach and SCNTB projects,
including all additional data obtained during PED investigations. The tables each include
a comparison of the composite data following the State compatibility standard and the
Wilmington District (SAW) compatibility practice, as discussed in Sections 1.4 and 1.5.
These tables both provide the mean native beach grain size and standard deviation as well
as the mean borrow area grain size and standard deviation. Also included in the tables
are the weighted composite for the fine-grained and granular material for the native beach
and the borrow areas.
The Topsail Beach CSDR project borrow area A (Figure 3) contains sufficient
compatible material for initial construction and each nourishment event following the
Wilmington District compatibility practice. However, the Wilmington District composite
compatibility includes approximately 1.5% more fine-grained sediment than what is
considered compatible under the state criteria (i.e. native = I %; 1%native + 5%
allowable over the native = 6% total allowable). Allowing this small incremental
increase of fine-grained sediment (Total = 7.5%) following the Wilmington District
compatibility practice retains approximately 23 MCY' of compatible material.
Adherence to the State compatibility standards would otherwise require portions of the
borrow area to be removed from the composite analysis to assure the percent of fine-
grained material does not exceed 6%, resulting in the equivalent loss of 7 MCY' from
borrow area A.
The borrow areas identified for the SCNTB CSDR project (i.e. G, H, J, L, O, and P)
contain less than 10% fine-grained material passing the #200 sieve and most are also
within the more stringent State sediment compatibility standards (i.e. less than 5% over
the native passing the #230 sieve), with the exception of borrow areas O and P. Based on
the State sediment compatibility standards, these borrow areas are acceptable if the
composite fine-grained sediment is equal to or less than 6.3%(Table 3 and Figure 3).
Implementation of the Wilmington District compatibility practice when conducting the
composite analysis for borrow area O resulted in the total sediment volume being
included in the total composite and 0.1 % more fine-grained sediment than allowed under
the State compatibility standard. However, this difference is considered negligible and
will not be further discussed in this EA. Borrow Area P has slightly more fine-grained
sediment (i.e. 2% more) when evaluated under the Wilmington compatibility practice
with a composite value of 8.3%. Based on the reduced material quantities from within
borrow area A (-7 MCY), which contained 1.3% more fines passing the #230 sieve, it is
expected that the reduction in the quantity of material for borrow area P is substantial.
' Volume is for the entire borrow and does not account for the additional volwne reduction as a result of
designated dredge cuts.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
The incremental increase in fine-grained sediment within borrow areas A, O, and P is
considered by the Wilmington District to be compatible for beach placement, since
previous experience with beach nourishment projects (i.e. Wrightsville, Carolina, Kure,
and Ocean Isle Beaches) has shown that high quality beaches can be constructed using
sand with up to 10% fines (up to 10% by weight passing the #200 sieve) with no adverse
environmental impacts.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Table 2. Mean sampling data from the native beach and Borrow Area A for the Topsail
Beach CSDR project. (* the State criteria do not consider the %passing the #200 sieves)
Native Beach
Borrow Area A
Slate2 SAWS
[DIt,atia
ihi
2.15
2.44 2.61
0.23
0.18 0.16
0.7
0.7 0.6
0.6
0.6 0.7
'Weight % Fines
(passing #200
1.0
-- 8.3
Weight % Fines
(passing 9230
1.0
5.9 7.5
Visual %Shell
11
8 6
Weight %Granular
(passing #10
99
94.9 96.3
Table 3. Mean sampling data from the native beach and borrow areas for the SCNTB
CSDR project. (* the State criteria do not consider the % passing the 4200 sieve])
Native
Borrow Area G
Borrow Area H
Borrow Area J
Borrow Area L
Borrow Area 0
Borrow Area P
State2
SAWS
Staten
SAW2
Staten
SAW2
Slate2
SAWS
Data
Beach
State' SAWS
State2 SAWS
Mean hi
2.15
2.26
2.17
2.45
2.48
2.01
1.92
1.63
1.57
2.18
2.22
2.05
2.32
Mean mm
0.23
0.21
0.22
0.18
0.18
0.25
0.26
0.32
0.34
0.22
0.21
0.24
0.20
Std Dev hi
0.7
0.7
0.9
0.5
0.4
0.9
0.9
1.3
1.4
0.8
0.7
0.8
0.7
Std Dev mm
0.6
0.6
0.5
0.7
0.8
0.5
0.5
0.4
0.4
0.6
0.6
0.6
0.6
"Weight %
Fines (passing
#200)
1.3
--
5.4
--
3.4
--
4.0
--
5.0
--
7
6T6.
--
86
Weight %
Fines
(passing
#230
1.3
4.5
5.1
3.1
3.2
3.5
3.8
3.8
4.8
5.5Visual%
Shell
9.4
3.8
3.4
2.8
2.2
8.7
7.9
12.3
11.8
5.3Weight
%
Granular
assin #10
98.1
96.2
94.8
98.6
98.8
94.6
92.7
90
87.9
94.8
' The #200 sieve = 0.074 nun / 3.75 phi and the #230 sieve = 0.063 mm / 4.0 phi. The # 10 sieve = 2.0 nun /
-1.0 phi.
' This columm meets the State compatibility standards.
This column contains sediment recommendations following the Wilmington District (SAW) compatibility
practice.

MW
S
NO
w

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Based on the data provided in Table 2 and Table 3, none of the identified borrow areas
exceed acceptable levels of calcium carbonate (shell) under the State standards.
Locations within the borrow areas that showed thick layers of shell hash during the PED
investigations were removed from the composite analysis and were not included as a part
of the borrow area use plan. However, two of the borrow areas for the SCNTB CSDR
project have more granular material than what is considered compatible under the State
standards (Table 3). In borrow area J there is 0.4% more granular material' when
conducting the borrow area composite analysis assuming the Wilmington District
compatibility practice. The slight increase of granular material over that prescribed by
the State standard for borrow area J is considered negligible and will not be further
evaluated as a component of this EA. Borrow Area L contains 5.2% more granular
material for the Wilmington District compatibility practice borrow composite than the
State standard. Based on the laboratory sample data for the vibracore borings it is known
that a large percentage of the granular material within this borrow area consists of
residual shell hash (i.e. the percent of the visually estimated shell is generally 100% for
most of the sieves used above the #10 sieve (2-19 mm)). There are potentially areas
within borrow area L that contain shell hash that were not located through the vibracore
sampling and will be managed accordingly, as discussed in Section 1.8.
1.8 Commitments for Borrow Area or Sediment Management
As discussed in the referenced Topsail Beach and SCNTB EISs, an environmental goal
for both projects is to avoid and minimize adverse impacts to the maximum extent
practicable. To achieve this goal with respect to sediment compatibility, borrow area
contingency plans were prepared and documented to avoid placing incompatible material
on the beach. These plans primarily include moving the dredge to another site within the
dredged borrow area or to another borrow area in the event that incompatible material is
encountered. The following language is from the "Borrow Area Contingency Plan"
sections 7.04.1.7 and 7.04.4 of the Topsail and SCNTB reports respectively:
"Furthermore, dredging production rates are specific to each dredge and its operation
and can be quantified. The recommended construction plan identified in Section 7.04.1.4
discusses the use of a hydraulic cutterhead pipeline dredge during initial construction
and the use of hopper dredges during each periodic nourishment event. For hydraulic
cutterhead pipeline dredges, once production rates are known for a given contract, a
prediction can be made of the dredging time and volume of material between the
instantaneous dredge location and the next known boring location of suitable material.
Thus, a qualitative and quantitative assessment can be made of whether this volume of
potentially incompatible material is significant relative to the overall project. Results
from these calculations will be used by appropriate United States Army Corps of
1 Based on the State standard of 5% more than the native beach, which is equal to 93.1 %.

Environmental Assessment
West Onslow, Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Engineers (USACE) personnel to determine whether the cutterhead dredge should
continue in the dredge's present location or relocate. During periodic nourishment
events, hopper dredges will utilize pump out facilities for each dredged hopper load.
Considering hopper dredges have a maximum capacity per load and are self propelled,
potential incompatible material can feasibly be managed by the Corps.
Federal and state environmental agencies will be notified if, and how much, potentially
incompatible material is encountered during dredging operations. If necessary, the
Wilmington District will make the decision on a suitable contingency measure which may
include moving the dredge to another site within the borrom area or to one of the other
designated borrow areas, depending on availability of sediment, and will notify the
agencies of this contingency measure."
As discussed in Section 1.7, portions of borrow areas J and L contain higher percentages
of granular material (i.e. shell hash). Referenced contingency plans will be in place to
avoid and/or remove areas of unacceptable granular material. Specifically, the
construction management process outlined above will be implemented to monitor for
incompatible material in the dredge (i.e. hopper dredge) and/or on the beach and direct
the dredge to relocate if necessary.
In addition to the dredging contingency plans to avoid incompatible material, paragraph
3(i) of 15A NCAC 07H.0312 states that "(dredging) techniques that take incompatible
sediment within a borrow site or combination of sites and make it compatible with that of
the recipient beach characterization shall be evaluated on a case -by -case basis by the
Division of Coastal Management." For the purpose of this assessment, the following
additional "dredging techniques" associated with the Topsail Beach and SCNTB projects
will be implemented which will result in a reduction of fine-grained sediment placed on
the beach and avoidance/removal of high percentages of granular material being placed
on the beach.
Coarsening of sediment: The physical activity of dredging sediment from a
borrow area and creating a slurry of sediment and water for pipeline transport and
placement on the beach results in a loss of fine-grained sediment into the water
column and/or surf zone and the settling of coarse material within the dredge (i.e.
hopper dredge) and on the beach. Consequently, the in situ percentages of fine-
grained material in the borrow area are higher than what is actually placed on the
beach.
Screening of granular material: Portions of borrow areas I and L have slightly
higher percentages of granular material (shell hash) than considered compatible
under the State standards and the Wilmington District practice. If granular
material is believed to be a persistent problem and opportunities to relocate the
dredge to a different area are unsuccessful, screens will be placed at the end of the
outflow pipe on the beach to catch and sieve granular material from the project
area beaches. Physical removal of this material from the beach and/or discharge
pipe through implementation of screening measures can be used to sieve out the

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
larger fractions while allowing for the course compatible sand to be placed on the
beach. This mitigative technique will be implemented if incompatible material is
encountered during dredging to allow for compatible sediment to be dredged and
placed for dune and berm construction. If material is placed on the beach and is
deemed incompatible, it will be tilled, sifted, removed, and properly disposed of.
All shell material will be properly disposed of in previously approved disposal
facilities.
2.0 Purpose and Need for the Proposed Project
Purpose. The purpose for the West Onslow Beach and New River Inlet (Topsail Beach)
and SCNTB CSDR projects is to reduce damages resulting from beach erosion and waves
along the ocean shoreline of the study area. To accomplish this, a dune and berm system
will be constructed on Topsail Island beach segments. Sand for the beachfill would be
delivered from offshore borrow areas by hydraulic dredging methodologies.
Need. Based on the Study phase geotechnical investigations, it appeared that sufficient
sediment was available to meet the 50 year project life. More complete geotechnical
investigations of the borrow areas have since been conducted during the PED phase for
both projects. The additional analyses resulted in a refinement in the borrow area
characterizations. A borrow area utilization plan needs to be developed which provides
compatible beach material for a 50 year project life.
3.0 Alternatives
This chapter presents a description of the alternatives considered and how those
alternatives would meet the overall purpose and need for the proposed action.
3.1 Proposed Action - Wilmington District Compatibility Practice (Preferred
Alternative)
The proposed action (preferred alternative) is to review the PED geotechnical data for
Topsail Beach and SCNTB CSDR project offshore borrow areas and implement a borrow
area utilization plan which includes the Wilmington District's compatibility practice for
beach placement of sediment. Specifically, this includes, but is not limited to,
implementation of. (1) a visual classification and laboratory analysis of vibracore
sediment samples, (2) use of the federal guidelines for calculating overfill ratios (Section
V-4-1.e.(2)i. of the U.S. Army Corps of Engineers Engineer Manual (EM) 1110-2-1100,
part V, titled Coastal Engineering Manual) and (3) an average weighted fine-grained
sediment content of less than 10% passing the #200 sieve. The proposed action would
provide approximately 13.6 MCY for Topsail Beach and approximately 14.6 MCY for
SCNTB of compatible dredged material for placement on the beach in order to meet the
50 year project life of both projects. A combination of dredging operational techniques
(i.e. coarsening of material through losses of fine-grained sediment during dredging and
placement activities), construction management measures (i.e. quality control monitoring,

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
coordination, and contingency planning), and screening measures (i.e. physical removal
of incompatible granular material) will be implemented to assure that sediment placed on
the beach is "compatible" with the native sediment. The proposed action would maintain
the current borrow area acreage impacts evaluated in the Topsail Beach and SCNTB EISs
and avoid the impacts associated with additional offshore investigations for borrow areas
and actual dredging and conveyance of sediment from those sites.
3.2 No Action
Under the no action Alternative, no changes would be made to the preliminary borrow
area utilization plans identified in the Topsail Beach and SCNTB EISs. The authorized
borrow areas would be utilized in compliance with the State sediment compatibility
standards. The borrow areas would be used until all identified beach compatible material
is exhausted. This alternative would not provide sediment volumes to support the 50 year
project life of both projects. Although the no action alternative does not meet the purpose
and need for this action, it was retained for comparison with the proposed plan and
therefore, discussed in Section 4 of this EA.
A NEPA document would be prepared to assess additional offshore borrow area
alternatives which contain compatible sediment in accordance with the State
compatibility standard. Inshore and/or upland borrow area alternatives would not be
considered as they had already been eliminated in the EISs based on detailed technical
criteria. The NEPA document would evaluate the incremental impacts of this change.
4.0 Affected Environment and Environmental Consequences
Descriptions of affected environment for both the West Onslow Beach and New River
Inlet (Topsail Beach), NC and SCNTB CSDR projects are provided in the following
integrated reports:
• US. Army Corps of Engineers, 2009. Final Integrated General Reevaluation
Report and Environmental Impact Statement, Shore Protection, West Onslow
Beach and New River Inlet (Topsail Beach), NC. February 2009.
• U.S. Army Corps of Engineers. 2010. Final Integrated Feasibility Report and
Environmental Impact Statement, Coastal Storm Damage Reduction, Surf City
and North Topsail Beach, North Carolina. December 2010.
This section describes the resource categories which may experience an incremental
change in impact from what was previously evaluated in the original EISs, as well as the
environmental effects associated with the alternatives presented in Section 3.0.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Summary of General Water Quality Impacts
During construction for both alternatives, there would be elevated turbidity and
suspended solids in the immediate area of hydraulic dredging and beach placement of
sediment when compared to the existing non -storm conditions of the surf zone. Potential
impacts of the proposed action associated with increased fine-grained sediment
percentages are primarily confined to the water column and may include increased
turbidity in the offshore dredging location, in the surf zone, and in the immediate area of
sand deposition. Significant increases in turbidity are not expected to occur outside the
immediate placement area (turbidity increases of 25 Nephelometric Turbidity Units
(NTU's) or less are not considered significant). Monitoring studies done on the impacts
of offshore dredging indicate that sediments suspended within the water column during
offshore dredging are generally localized and rapidly dissipate when dredging ceases
(Nagvi and Pullen 1983, Bowen and Marsh 1988, Van Dolah et al. 1992). The
incremental change in fine-grained sediment associated with the proposed action would
not change the conclusion that the impacts should be temporary and minor and are not
expected to exceed the impact threshold evaluated in the original EISs.
The following sections describe potential impacts associated with each alternative
relative to specific resource categories:
4.1 Surf Zone Fishes
Impacts of the Proposed Action
The proposed action would result in slight increase in the percentage of fine-grained
sediment placed on the beach from what was previously evaluated in the original EISs.
However, this increase would not exceed the 10% fine-grained sediment threshold
established under the Wilmington District compatibility practice from which multiple
successful CSDR and navigation projects have been previously constructed with no
known long term adverse impacts to surf zone fishes.
As previously discussed in the referenced EISs, placement of"beach quality" sand on the
beach could result in increased turbidity and mortality of intertidal macrofauna, which
serves as food sources for various surf zone fish species. Feeding activities of these
species may be interrupted in the immediate area of beach sand placement; however,
these adaptive mobile species are expected to temporarily relocate to other areas as the
project proceeds along the beach and only a small area is impacted at any given time, and
once complete, organisms can recruit into the nourished area. Turbidity concentrations
and suspended sediments in the surf zone increase relative to increasing percentages of
fine-grained sediment during beach placement operations. However, the opportunistic
behavior of these organisms within the dynamic surf zone environment enables them to
adapt to short-term disturbances. The incremental increase in fine-grained material up
to 10% is not expected to adversely impact surf zone fishes and their prey sources beyond
the impact threshold evaluated in the original EISs.

Environmental Assessment
West Onslow Beach and New River Inlet ('Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Impacts of the No Action Alternative
No change to previous impacts previously discussed in the referenced EISs. Placement
of "beach quality" sand on the beach could result in increased turbidity and mortality of
intertidal macrofauna, which serves as food sources for various surf zone fish species.
Feeding activities of these species may be interrupted in the immediate area of beach
sand placement; however, these adaptive mobile species are expected to temporarily
relocate to other areas as the project proceeds along the beach and only a small area is
impacted at any given time, and once complete, organisms can recruit into the nourished
area. Turbidity concentrations and suspended sediments in the surf zone increase relative
to increasing percentages of fine-grained sediment during beach placement operations.
However, the opportunistic behavior of these organisms within the dynamic surf zone
environment enables them to adapt to short-term disturbances.
Under the No Action Alternative, available borrow area resources would be exhausted
prior to the 50 year life of both projects. Additional investigations for compatible borrow
material would be pursued further offshore. Borrow sources located further offshore
could increase the amount of time required to complete a nourishment event.
4.2 Benthic Resources — Surf zone
Impacts of the Proposed Action
The proposed action may have short term negative impacts on intertidal macrofauna
through increased turbidity in the surf zone during placement or changes in the sand grain
size or beach profile. However, as previously discussed in the referenced EISs, recovery
of these opportunistic infauna species occurs quickly (i.e. 1-4 years) depending on
sediment compatibility (Hayden and Dolan, 1974; Reilly and Bellis, 1978; Saloman and
Naughton, 1984; Nelson, 1989; Van Dolah et al., 1992; Van Dolah et al., 1993; Hackney
et al., 1996; Jutte, P.C. et al., 1999; Peterson et al., 2000). Though the proposed action
would result in an increase in allowable fine-grained material up to 10%, the incremental
increase in the percentage of fine-grained sediment compared to the no action alternative
is negligible with respect to recovery rates. While the proposed action will impact
intertidal macrofauna within the immediate vicinity of the placement area, these effects
will be localized, short-term, and reversible and would not exceed the "compatibility"
context of the published literature or the impact threshold evaluated in the original EISs.
Impacts of the No Action Alternative
No change to previous impacts previously discussed in the referenced EISs. Under the
no action alternative, available borrow area resources would be exhausted prior to the 50
year life of both projects. Additional investigations for compatible borrow material
would be pursued further offshore. Borrow sources located further offshore could
increase the amount of time required to complete a nourishment event and may indirectly
impact benthic intertidal macrofauna by extending the construction schedule.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
4.3 Benthic Resources—Nearshore Ocean
Impacts of the Proposed Action
Under the proposed action, there would be no change in impacts to the post dredging
environment in the borrow areas. Impacts to the benthic populations of the borrow area - -
associated with hydraulic dredging related turbidity will be localized and temporary and
would not exceed the impact threshold considered in the referenced EISs.
Impacts of the No Action Alternative
Under the no action alternative, available borrow area resources would be exhausted prior
to the 50 year life of both projects. In order to provide sufficient material to support the
remaining nourishment events, additional borrow area investigations would likely be
pursued further offshore resulting in an increase in the cumulative acreage of direct
benthic resource impacts for both projects.
4.4 Essential Fish Habitat
Potential project effects on EFH species and their habitats have been previously evaluated
in the referenced EISs for both projects which determined that the proposed action of
dredging and beach fill construction would not have a significant adverse effect on such
resources. Compliance obligations related to EFH provisions of the 1996 congressional
amendments to the Magnuson -Stevens Fishery Conservation and Management Act
(MSFCMA) (P.L. 94-265) have been satisfied through these previous consultations for
both projects. Additionally, previously coordinated mitigative conditions, as well as those
discussed in this document, will be implemented to minimize physical and biological
impacts to EFH and to assure that any adverse effects are short term and localized on an
individual and cumulative effects basis. Realizing that hard bottom communities occur
within the project area and are designated Habitat Areas of Particular Concern (HAPC),
additional evaluation of impacts relative to each alternative are provided below.
Hard Bottoms
While hard bottoms are most abundant in southern portions of North Carolina, they occur
along the entire NC coast. Based on multiple surveys conducted offshore of Topsail
Island, hard bottom communities are primarily located offshore of Surf City and North
Topsail Beaches. According to Cleary (2003), the environment offshore of the SCNT13
project area is characterized by undulating, relatively flat, hard -bottom platform
punctuated by scattered, low -relief, hard -bottom scarps (moldic limestone and siltstone)
and sediment -filled depressions. Side scan sonar and diver ground truth data were used
to identify and delineate low, moderate, and high relief hard bottom features within the
proposed borrow areas. Mitigative buffers were established in the SCNTB EIS to avoid
direct and indirect impacts to these resources and include a 500-meter, hard -bottom
buffer around high- and moderate -relief hard bottom and a 122-m (400-ft.) buffer around
low -relief hard bottom. Detailed hard bottom discussions for both projects are included
within the referenced EISs.

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
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Impacts of the Proposed Action
Hydraulic dredging operations have two types of sedimentation and turbidity sources
including: (I) suspension of sediment at the cutterhead and/or draghead and (2)
suspension of sediment associated with hopper dredge overflow as fine-grained
suspended sediments within the slurry are washed overboard through overflow ports. The
extent of the sediment plumes produced depends on the type of dredge, how it is
operated, currents, and the nature of the sediments in the dredged area. Dredging of sandy
sediments minimizes the amount of turbidity and sedimentation associated with the
dredging operation and reduces the suspension time and advection distance of overflow
sediments. The proposed action would slightly increase the percentage of fine-grained
sediment; however, the material would still be 90% sand. It is not expected that the
minor increase in fine-grained sediment would result in an incremental increase in
dispersion distance that would require additional buffers to avoid adverse effects to hard
bottom resources. Based on the existing survey data collected of the hard bottom
resources within the project are, the species present are adapted to high sedimentation
rates in the natural environment. The potential increase in turbidity and sedimentation
associated with the proposed action is considered negligible and would not exceed the
impact threshold evaluated in the referenced EISs.
Impacts of the No Action Alternative
Under the no action alternative, available borrow area resources would be exhausted prior
to the 50 year life of both projects. Additional borrow area investigations would be
pursued further offshore with a high likelihood of encountering additional moderate and
high relief hard bottom communities requiring additional surveys, coordination, and
development of mitigative buffers.
4.5 Endangered and Threatened Species
Impacts of the Proposed Action
Potential project effects on threatened and endangered species in accordance with Section
7 of the ESA of 1973 have been previously evaluated in the referenced EISs for both
projects. Implementation of the proposed action would not affect listed species or critical
habitat in a manner or to an extent not considered in the previous consultation; therefore,
reinitiation of consultation is not required.
Impacts of the No Action Alternative
Under the no action alternative, available borrow area resources would be exhausted prior
to the 50 year life of both projects: Additional investigations for compatible borrow
material, in accordance with the State compatibility standards, would be pursued further
offshore. The use of additional offshore borrow material could increase the amount of
time required to complete a nourishment event due to longer haul distances. The hopper

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2017
dredging window for both projects is during the colder water months from l December to
31 March to avoid and/or minimize sea turtle entrainment risk. Increased haul distances
could require additional time to complete a nourishment event; thus, increasing the risk of
sea turtle entrainment.
4.6 Recreation and Aesthetic Resources
Impacts of the Proposed Action
Under the proposed action, there would be no change in impacts to the recreation and
aesthetic quality of the project areas. As discussed in Sections 4.1 and 4.2, localized and
temporary impacts to fish and benthic invertebrates within the surf zone may occur;
which could indirectly impact recreational fishing. However these effects would not be
significant as they would only occur during construction would be limited to the area
where material is being placed on the beach. Such localized temporary impact can easily
be avoided by anglers in the area. As previously discussed, though the proposed action
would result in slight increases in the amount fine material dredged from the borrow site,
the in -place fill material on the beach would be coarser and would not be aesthetically
discernible by recreational users.
Impacts of the No Action Alternative
Under the no action alternative, available borrow area resources would be exhausted prior
to the 50 year life of both projects. Additional investigations for compatible borrow
material, in accordance with the State criteria, would be pursued further offshore. The
use of additional offshore borrow material could increase the amount of time required to
complete a nourishment event due to longer haul distances. The hopper dredging
window for both projects is during the colder water months from l December to 31
March, outside of the peak recreation season, to avoid and/or minimize resource impacts.
Increased haul distances could require additional time to complete a nourishment event;
thus, adding risk of additional recreation impacts.

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
4.7 Environmental Impact Comparison of Alternatives
Table 4. Summary and comparison of impacts to each resource category relative to the
preferred and no action alternatives.
Resource
Proposed Action
No Action Alternative
• Localized short term increase
• Localized short term increase in
in turbidity within the
turbidity within the offshore
offshore dredging location,
dredging location, in the surf zone,
in the surf zone, and in the
and in the immediate area of sand
immediate area of sand
deposition.
deposition.
Water
• Additional borrow areas would
Quality
• The percentage of increase in
likely be pursued further offshore
fine-grained sediment is
resulting in the potential
negligible and impacts are
cumulative increase in total area of
not expected to exceed the
dredging related turbidity within
threshold evaluated in the
the water column offshore.
original EISs.
• Localized short term
• Localized short term turbidity
turbidity disturbance
disturbance confined to the beach
confined to the beach
placement location during
placement location during
construction.
Surf Zone
construction.
Fishes
• Additional borrow areas would
• The percentage of increase in
likely be pursued further offshore
fine-grained sediment is
resulting in the potential increase
negligible and impacts are
in construction duration and risk of
not expected to exceed the
extending into the peak
threshold evaluated in the
recruitment and abundance periods
original EISs.
of surf zone fishes.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects.
Resource
Proposed Action
No Action Alternative
• Localized, short-term, and
• Localized, short-term, and
reversible impacts to benthic
reversible impacts to benthic
intertidal macrofauna from
intertidal macrofauna from direct
direct burial, increased
burial, increased turbidity in the
Benthic
turbidity in the surf zone, or
surf zone, or changes in the sand
Resources —
changes in the sand grain
grain size or beach profile.
Surf Zone
size or beach profile.
. Additional borrow areas would
• The percentage of increase in
likely be pursued further offshore
fine-grained sediment is
resulting in the potential increase
negligible and impacts are
in construction duration and risk of
not expected to exceed the
extending into the peak
threshold evaluated in the
recruitment and abundance periods
original EISs.
of intertidal macrofauna.
• Localized and temporary
Localized and temporary turbidity
Benthic
turbidity impacts would not
impacts.
Resources -
Nearshore
exceed the impact threshold
considered in the referenced
• Additional borrow areas would
Ocean
EISs.
likely be pursued further offshore
resulting in the potential increase
in cumulative acreage of direct
benthic resource impacts.
• The percentage of increase in
• Additional borrow areas would
fine-grained sediment is
likely be pursued further offshore
negligible and would not
with a high likelihood of
result in an incremental
encountering additional moderate
EFH — Hard
effect not previously
and high relief hard bottom
Bottoms
evaluated or result in an
communities requiring additional
increase in sediment
surveys, coordination, and
dispersion that would require
development of mitigative buffers.
a reevaluation of buffer
distances.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Resource -
Proposed Action
No Action Alternative
• Implementation of the
Additional borrow areas would
proposed action would not
likely be pursued further offshore.
Endangered
affect listed species or
Increased haul distances could
and
critical habitat in a manner or
require additional time to complete
Threatened
to an extent not considered in
a nourishment event; thus,
Species
the previous consultation;
increasing the risk of sea turtle
therefore, reinitiation of
entrainment.
consultation is not required.
• The percentage of increase in
• Additional borrow areas would
fine-grained sediment is
likely be pursued further offshore.
Recreation
negligible and would not
Increased haul distances could
and
result in a discernible
require additional time to complete
Aesthetic
increase in impacts to
a nourishment event and extend
Resources
recreational and aesthetic
into the peak recreation season.
resources.

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
4.8 Unavoidable Adverse Impacts of the Proposed Action
Construction of the proposed action would not result in incremental impacts of
significance beyond those evaluated as a component of the referenced EISs for both
projects. Impacts would be short term and immediately confined to the actual dredging
and placement locations. Implementation of previously developed contingency plans as
well as the additional measures discussed in Section 1.8 would further minimize the risk
of environmental impacts.
4.9 Cumulative Impacts
Cumulative effects have been defined by the CEQ in 40 CFR 1508.7 as: "the impact on
the environment which results from the incremental impact of the action when added to
other past, present, and reasonably foreseeable future actions regardless of what agency
(Federal or non -Federal) or person undertakes such other actions." The cumulative
impacts of the Topsail Beach and SCNTB projects were discussed in the referenced EISs.
The cumulative impacts associated with the proposed action would not be of significance
beyond what was evaluated within the original cumulative effects analysis for both
projects. However, under the no action alternative there would be cumulative impacts
associated with the incremental increase in the total acreage of borrow areas impacted
offshore and the potential increase in total construction time to complete both projects.
5.0 Compliance with Environmental Requirements
The incremental changes documented in this EA associated with the proposed action will
not change environmental compliance determinations made in the EISs for both the
Topsail Beach and SCNTB projects relative to pertinent Executive Orders and Federal,
State, and local requirements. Though no significant changes are expected, compliance
with the North Carolina Coastal Management Program warrants additional discussion
considering that pertinent issues relative to the State sediment compatibility standards.
5.1 North Carolina Coastal Management Program
The proposed action will be conducted in the designated coastal zone of the State of
North Carolina. Pursuant to the federal CZMA of 1972, as amended (PL 92-583), federal
activities are required to be consistent, to the maximum extent practicable, with the
federally approved coastal management program of the state in which their activities will
occur. By letters dated November 7, 2006 (CD06-OS4; DCM#20060059) and April 16,
2010 (CD10-017; DCM#20100006) the NCDCM concurred that the proposed Federal
activities are consistent, to the maximum extent practicable, with the enforceable policies
of North Carolina's coastal management program for both the Topsail Beach and SCNTB
projects respectively. All conditions of these consistency determinations will be followed.
The Topsail Beach consistency determination notes the following:

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
"Should the proposed action be modified, a revised consistency determination could be
necessary. This might take theform ofeither a supplemental consistency determination
pursuant to 15CFR 930.46 or a new consistency determination pursuant to 15CFR
930.36. Likewise, iffurther project assessments reveal environmental effects not
previously considered by the proposed development, a supplemental consistency
certification may be required. "
As previously discussed, though the State compatibility standards have since been passed
by the NCCRC they have not been submitted to the NOAA's OCRM for consideration as
a federally approved component of the State's coastal management program. In the
absence of this OCRM approval, the State sediment compatibility standards are not
required as a component of the Federal consistency determination in accordance with the
CZMA. Additionally, though this EA evaluates the potential incremental impacts of
utilizing a borrow area plan which adheres to the Wilmington District compatibility
practice the incremental impacts do not exceed the impact threshold discussed in the
referenced EISs for both the Topsail Beach and SCNTB projects. The projects remain as
they were previously described. The Corps does not consider this to be a project
modification and; therefore, does not believe that a supplemental or new consistency
determination is warranted.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
6.0 Agency and Public Involvement
The EA is being circulated for a 30-day review and comment period to the agencies and
individuals listed below:
Federal Agencies
U.S. Environmental Protection Agency
U.S. Department of Agriculture
U.S. Department of Interior
U.S. Fish and Wildlife Service
Federal Highway Administration
Federal Emergency Management Agency
US Coast Guard Marine Safety Office
Advisory Council on Historic Preservation
DOI, Office of Environmental Policy & Compliance
US Department of Housing & Urban Development
US Forest Service
Bureau of Ocean Energy Management
National Marine Fisheries Service - Southeast Regional Office
National Marine Fisheries Service — Habitat Conservation Division
State Agencies
NC Department of Environment and Natural Resources
NC Wildlife Resources Commission
NC Division of Coastal Management
NC Coastal Land Trust
NC Department of Transportation
NC Department of Cultural Resources
NC Fisheries Association
NC Department of Administration - State Environmental Review Clearinghouse
NC Commission of Indian Affairs
NC Shellfish Sanitation
Elected Officials
Town of Topsail Beach, NC
Town of Surf City, NC
Town of North Topsail Beach, NC
Local Agencies/Entities
County Administrators
County Emergency Management Offices

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
County Health Departments
City Managers
County Managers
Local Newspapers and Postmasters
Local Libraries
Local CAMA officers
Local Commissioners
Universities
University of NC at Wilmington
Duke University
Cape Fear Community College
Conservation Groups
Environmental Defense Fund
National Wildlife Federation
Karen Beasley Sea Turtle Hospital
The Wilderness Society
National Audubon Society
North Carolina Coastal Federation
The Nature Conservancy

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
7.0 Point of Contact
Any comments or questions regarding this EA should be addressed to:
Mr. Doug Piatkowski
U.S. Army Corps of Engineers
Wilmington District
69 Darlington Avenue
Wilmington, NC 28403
[phone]
[e-mail]

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
8.0 Finding
The Proposed action would not significantly impact the quality of the human
environment. If this opinion is upheld following circulation and review of this EA, a
Finding of No Significant Impact (FONSI) will be signed and circulated.

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West Onslow Beach and New River Inlet ('Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Julv 2013
9.0 Preparers
This document was prepared and reviewed by the US Army Corps of Engineers
Wilmington District.
Prepared By:
Doug Piatkowski, Biologist, Environmental Resources Section, USACE Wilmington
District Office.
Erin Williams, Civil Engineer, Geotechnical Section, USACE Wilmington District
Office.
Reviewed By:
Phil Payonk, Chief, Environmental Resources Section, USACE Wilmington District
Office.
Mitch Hall, Chief, Geotechnical Section, USACE Wilmington District Office.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
10.0 References
Bowen, P.R., and G.A. Marsh. 1988. Benthic Faunal Colonization of an Offshore Borrow
Pit in Southeastern Florida. Misc. Rept. D-88-5. U.S. Army Corps of Engineers,
Dredging Operations Technical Support program, Vicksburg, MS. - —
Cleary, W.J. 2003. An Assessment of the Availability of Beachfill Quality Sand Offshore
North Topsail Beach and Surf City North Carolina. HDR Engineering, Inc., of the
Carolinas, Sunset Beach, NC.
Hackney, C.T., M.H. Posey, S.W. Ross, and A.R. Norris. 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, NC.
Hayden, B., and R. Dolan. 1974. Impact of beach nourishment on distribution of Emerita
talpoida, the common mole crab. Journal of the American Waterways, Harbors, and
Coastal Engineering Division, ASCE 100: W W2. pp. 123-132.
Jutte, P.C., R.F. Van Dolah, M.V. Levisen, P. Donovan-Ealy, P.T. Gayes, and W.E.
Baldwin. 1999. An Environmental Monitoring Study of the Myrtle Beach Renourishment
Project: Physical and biological Assessment of Offshore Sand Borrow Site, Phase I —
Cherry Grove Borrow Area, Final Report. Prepared for the US Army Engineer District,
Charleston, SC, by the South Carolina Marine Resources Research Institute, South
Carolina Marine Resources Division, Charleston, SC.
Naqvi, S.M., and C.H. Pullen. 1982. Effects of beach nourishment and borrowing on
marine organisms. U.S. Army Corps of Engineers, Coastal Engineering Research Center,
Misc. Rept. 82-14. Vicksburg, MS.
Peterson, C.H., D.H.M. Hickerson, and G.G. Johnson. 2000. Short-term consequences of
nourishment and bulldozing on the dominant large invertebrates of a sandy beach.
Journal of Coastal Research 16(2):368-378.
Nelson, W.G. 1989. An Overview of the Effects of Beach Nourishment on the Sand
Beach Fauna. In Beach Preservation Technology '88: Problems and Advancements in
Beach Nourishment, ed. L.S. Tait. pp. 295-310. Florida Shore and Beach Preservation
Association, Tallahassee, FL.
Reilly, F.J. Jr., and V.J. Bellis. 1978. A Study of the Ecological Impact of Beach
Nourishment with Dredged Materials on the Intertidal Zone. Technical Report No. 4.
Institute for Coastal and Marine Resources, Greenville, NC.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Saloman, C.H., and S.P. Naughton. 1984. Beach restoration with offshore dredged sand:
Effects on nearshore macrofauna. NOAA Tech. Mem. NMFS-SEF-133. U.S. Department
of Commerce, National Oceanic and Atmospheric Administration, St. Petersburg, FL.
USACE, 2009. Final Integrated General Reevaluation Report and Environmental Impact
Statement, Shore Protection, West Onslow Beach and New River Inlet (Topsail Beach),
NC. February 2009.
USACE, 2010. Final Integrated Feasibility Report and Environmental Impact Statement,
Coastal Storm Damage Reduction, Surf City and North Topsail Beach, North Carolina.
December 2010.
Van Dolah, R.F., P.H. Wendt, R.M. Martore, M.V. Levisen, and W.A. Roumillat. 1992.
A Physical and Biological Monitoring Study of the Hilton Head Beach Nourishment
Project. Marine Resources Division, South Carolina Wildlife and Marine Resources
Department, Charleston, South Carolina.
Van Dolah, R.F., R.M. Martore, and M.V. Levisen. 1993. Physical and biological
monitoring study of the Hilton Head beach nourishment project. Prepared for the Town
of Hilton Head Island by the South Carolina Marine Resources Research Institute, South
Carolina Marine Resources Division, Charleston, SC.
15A NCAC 07H .0312, Technical Standards for Beach Fill Projects
(http://www.nccoastalmanagement.net/Rules/7H%200312.pdfl

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Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
APPENDIX A
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
A Summary of Report Sections Referencing the North Carolina State Sediment
Compatibility Standards

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Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
1.0 Introduction
A comprehensive review of all Final report documents and appendices for both the
Topsail Beach and Surf City and North Topsail Beach (SCNTB) Coastal Storm Damage
Reduction (CSDR) projects was conducted. All sections containing reference to
sediment compatibility and the North Carolina (NC) state sediment compatibility
standards were copied and organized in this appendix relative to the project, report
section, and appendix titles. References to sediment compatibility commitments were
made as a component of the NEPA documentation, USFWS Fish and Wildlife
Coordination Act (FWCA) recommendations, and the Section 7 Endangered Species Act
Biological Assessment.
2.0 Topsail Beach and SCNTB Report Sections Referencing Sediment
Compatibility
Topsail Beach CSDR Project
U.S. Army Corps of Engineers, 2009, Final Integrated General Reevaluation Report and
Environmental Impact Statement, Shore Protection, West Onslow Beach and New River
Inlet (Topsail Beach), NC. February 2009.
• 5.06.3 Borrow site comparisons (n2.104)
A sediment compatibility analysis was performed for all potential borrow areas for this
project. The analysis compared the grain size of the "native beach" or the "reference
beach" with the material in the potential borrow area. The overfill ratio is the primary
indicator of the compatibility of the borrow material to the beach material, with a value of
1.00 indicating that one cubic yard of borrow material is needed to match one cubic yard
of beach material. The procedure for calculating the overfill ratio for borrow areas in
relation to the reference beach was performed in accordance with the U.S. Army Corps of
Engineers Coastal and Hydraulics Laboratory Automated Coastal Engineering System
(ACES) software version 4.01.
• 8.03.3.3 Sediment Compatibility (pg. 200)
The compatibility analysis compared the grain size of the "native beach" or the
"reference beach" with the material in the proposed borrow areas. The overfill ratio is
the primary indicator of the compatibility of the borrow material to the beach material,
with a value of 1.00 indicating that one cubic yard of borrow material is needed to match
one cubic yard of beach material. The procedure for calculating the overfill ratio for
borrow areas in relation to the reference beach was performed in accordance with the

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
U.S. Army Corps of Engineers Coastal and Hydraulics Laboratory Automated Coastal
Engineering System (ACES) software version 4.01. This procedure is discussed in
section V-4-1.e.(2)i. of the U.S. Army Corps of Engineers Engineer Manual (EM) 1110-
2-1100, part V, titled Coastal Engineering Manual. As stated in this manual, an overfill
ratio of 1.00 to 1.05 is considered optimum for sediment compatibility. However,
obtaining this level of compatibility is not always possible due to limitations in available
borrow sites. The overfill ratios for all of the potential borrow areas for the Topsail
Beach project are shown in Table 7.1. Table 7.1 also illustrates the average silt content
(#200 sieve) was less than 10% for all borrow areas.
• 11.03 Fish & Wildlife Coordination (pg. 243)
5. USFWS Recommendation: If beach construction is ultimately undertaken, the fill
material should have a high degree of compatibility with the native beach. The North
Carolina Sediment Criteria Rule, contained in the Technical Standards for Beach Fill
Projects (15A NCAC 07H .0312), should be used in regard to grain size and percent
weigh of calcium carbonate. In addition, compatibility should be established for other
important characteristics such as organic content, heavy mineral content, and color.
Corps Response: The proposed borrow area sediments for this project will comply with
grain size and percent weight requirements specified in 15A NCAC 07H .0312, Technical
Standards for Beach Fill Projects. However, there are no Federal or State requirements
for compatibility in regards to organic content, heavy mineral content, or color.
Therefore, a compatibility analysis for these items will not be conducted.
6. USFWS Recommendation: If beach construction is ultimately undertaken, there
should be a plan to monitor the quality of the fill material as it placed on the beach.
There should be an effective procedure for stopping operations if inappropriate material
is being pumped onto the beach. Since such real time protective measures may not be
completely effective, there should also be a plan for inspecting the constructed beach for
areas of incompatible material and removing such material before the start of the nest sea
turtle nesting season.
Corps Response: See Section 7.04.1.7 of the final report titled, "Borrow Area
Contingency Plan." This section thoroughly discusses the Corps intent to perform
rigorous boring analyses of proposed borrow areas in order to minimize the risk of
placing incompatible material on the beach as well as contingency measures for
cutterhead pipeline and hopper dredge operations if incompatible material is
unexpectedly encountered. Throughout the duration of construction operations, the
Corps employs full time construction inspection personnel to perform on -sight
inspections of the project operations to assure quality control and compliance with
contract specifications.
Appendix I —Biological Assessment

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West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Based on geophysical analyses and sediment compatibility analyses from identified
borings (Appendix C), the dredged material to be placed on the beaches averages > 90
percent sand. Most of the remaining material consists of fine grain particles (silt and
clay), which will not remain on the beach. These fines may temporarily lead to a - -
darkening of the beach. If this darkening persisted it could raise the temperature of nests
in the area, and potentially change the sex ratio of the hatchlings. If sand compaction in
the nourishment area exceeds 500 cone penetrometer units (CPUs), tilling will be
performed, and scarps over 18 inches and 100 ft. or longer will be graded.
Appendix T - Comments and Responses
3.30.12 NCDCM Comment: Only beach quality sand shall be used for beach
nourishment purposes. Should the dredging operations encounter sand deemed non -
compatible with native grain size or sorting characteristics of the native beach, the dredge
operator shall immediately cease operation and contact the NCDCM. Dredge operations
will resume only after resolution of the issue of sand compatibility.
Corps Response: All borrow areas will be characterized to comply with the new Coastal
Resources Commission sediment compatibility rules. As discussed in Section 8,
Environmental Effects, the use of compatible beach fill material will have minimal
resources impacts. Section 7.04.1.7, Borrow Area Contingency Plan, describes the
process to comply with the compatibility rules.
3.30.13 NCDCM Comment: The Corps should be advised that the Coastal Resources
Commission (CRC) is currently developing new sediment compatibility standards. Once
these new standards are passed by the CRC, and assuming these standards are approved
by OCRM as a federally approved component of the State's coastal management
program, these new standards will apply to future beach nourishment projects from that
point forward. The Corps is strongly encouraged to closely follow the development of
these new standards. The Corps should also incorporate any such standards into the
planning process for the proposed project.
Corps Response: Agree. Proposed borrow area sediments meet the new CRC
compatibility standards.
3.31.7 Environmental Defense Comment: As the Corps is well aware, the Coastal
Resources Commission is in the process of finalizing proposed sediment compatibility
standards for beach fill projects. This project would be subject to those rules should it
move forward and we assume that the standards for fine material, coarse material and
carbonate content' are being kept in mind as further characterization of borrow areas
occurs.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
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Corps Response: Noted. The Corps evaluated the potential borrow areas for this project
in accordance with the most recent CRC proposed sediment compatibility standards dated
March 24, 2006. The current proposed borrow areas meet these standards and will be
further evaluated to comply with the CRC proposed characterization standard for borrow
sites as stated in section 7.04.1.6.
3.31.8 Environmental Defense Comment: Finally, we are supportive of the Corps
effort to develop a borrow area contingency plan, and look forward to evaluating this in
the final EIS. Presumably this would include mitigation in the event of unexpectedly
encountering incompatible material.
Corps Response: Noted. The project will comply with the new Coastal Resources
Commission sediment compatibility rules. Beach fill material quality will be achieved
through characterization of the borrow material with an intense array of borings with
horizontal spacing of 500 feet to 1,000 feet. Mitigation, if required, will be in accordance
with Coastal Resources Commission recommendations.
North Carolina Division of Coastal Management (NCDCM) — Letter dated 7
November 2006
Subject: CD06-0S4 - Consistency Concurrence for Proposed Shore Protection Project
at Topsail Beach, Onslow and Pender Counties, North Carolina (DCM#20060059)
• Only beach quality sand shall be used for beach nourishment purposes.
Should the dredging operations encounter sand deemed non -compatible with native
grain size or sorting characteristics of the native beach, the dredge operator shall
immediately cease operation and contact the NCDCM. Dredge operations will resume
only after resolution of the issue of sand compatibility.
The Corps should be advised that the Coastal Resources Commission (CRC)
is currently developing new sediment compatibility standards. Once these new
standards are passed by the CRC, and assuming these standards are approved by
OCRM as a federally approved component of the State's coastal management
program, these new standards will apply to future beach nourishment projects from
that point forward. The Corps is strongly encouraged to closely follow the
development of these new standards. The Corps should also incorporate any such
standards into the planning process for the proposed project.
Should the proposed action be modified, a revised consistency
determination could be necessary. This might take the form of either a supplemental
consistency determination pursuant to 15CFR 930.46. or anew consistency
determination pursuant to 15CFR 930.36. Likewise, if further project assessments
reveal environmental effects not previously considered by the proposed development,
a supplemental consistency certification may be required. If you have any questions,
please contact Stephen Rynas at 252-808-2808.

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
Surf City and North Topsail Beach CSDR Project
U.S. Army Corps of Engineers. 2010. Final Integrated Feasibility Report and
Environmental Impact Statement, Coastal Storm Damage Reduction, Surf City and North
Topsail Beach, North Carolina. December 2010.
• 7.03.6 Environmental Monitorine and Other Commitments (Pa. 120)
Table 7.2
(1) Only beach compatible sediment (i.e., in accordance with North Carolina Sediment
Criteria Rule Language) would be placed on the beach as a component of this project
(Sections 10.06.1 and 11.02)
• 7.04.1 Borrow Area Material Compatibility (ne. 130)
North Carolina implemented new beach fill standards in 2007, which require
compatibility of the native beach with borrow sources in regards to the percentage of silt
(< 0.062 mm), granular sediment, (< 4.76 mm and > 2.0 mm), gravel (> 4.76 mm), and
calcium carbonate. The state still needs to gain approval from NOAA to add the new
standards to their Coastal Zone Management Program. If NOAA approves the changes,
then the new criteria would need to be met in order for the project to be consistent with
the Coastal Zone Management Act. A visual estimate of shell content can be used in lieu
of carbonate weight percent for samples collected before the effective date of beach fill
rules that applies to the Surf City/North Topsail Beach project. The standards require that
percent silt, granular sediment, and gravel in borrow material not exceed the amount
found in the native beach plus 5 percent, and the percent carbonate in borrow material not
exceed the amount found in the native beach plus 15 percent. Those characteristics for
the native beach and borrow material are given in Table 7.4. The analysis for the native
beach material indicates the silt, granular sediment, and gravel content are 1.2, 1.1, and
0.5 percent, respectively. The visual shell content for the native beach is 9 percent. After
incorporating the tolerance permitted by the beach fill standards, the silt, granular
sediment, gravel, and shell content permitted for borrow areas to be used for Surf
City/North Topsail Beach are 6.2, 6.1, 5.5, and 24 percent, respectively. As shown in
Table 7.4, all the borrow areas comply with the beach fill standards regarding the
percentage of silt with the exception of borrow areas A (6.6 percent) and L (6.3 percent).
Both of those borrow areas exceed the standard slightly by 0.4 and 0.1 percent,
respectively. All the borrow areas comply with the beach fill standards regarding the
percentage of granular sediment with the exception of borrow areas F (7.0 percent) and S
(6.6 percent), which exceed the standard by 0.9 and 0.5 percent, respectively. All the
borrow areas comply with the beach fill standards regarding the percentage of gravel
sediment with the exception of borrow areas F (8.5 percent) and P (6.6 percent), which

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
exceed the standard by 3.0 and 1.1 percent, respectively. All the borrow areas comply
with the beach fill standards regarding the percentage of shell content (carbonate). The
borrow areas in which the standards are exceeded for the various characteristic (A, F, L,
S, and P) have been retained because all borrow areas would be further characterized
during the design phase of the project. Additional vibracores would be performed to
comply with the beach fill standards of I core/acre or 1,000 foot spacing. Vibracores
would be performed to produce a density of 1,000 foot spacing in a borrow area before its
use as a borrow source.
Contingency measure if incompatible material is encountered
Federal and state environmental agencies would be notified if, and how much, potentially
incompatible material is encountered during dredging operations. If necessary, the
Wilmington District would make the decision on a suitable contingency measure that
could include moving the dredge to another site in the borrow area or to another borrow
area, depending on availability of sediment, and would notify the agencies of the
contingency measure.
• 8.01.6 Benthic Resources —Beach and Surf Zone (pg. 164)
To assure compatibility of nourishment material with native sediment characteristics and
minimize impacts to benthic invertebrates from the placement of incompatible sediment,
all sediment identified for use for the project would meet the Technical Standards for
Beach fill Projects (15A NCAC 07H.0312) identified in the NCDCM rule language.
• 8.01.8.2 Impacts on Hard Bottoms (pe. 173)
Hopper Dredge —Sedimentation and Turbidity
The distance that sediment plumes can extend depends on the type of dredge, how it is
operated, currents, and the nature of the sediments in the dredged area. As discussed in
Section 7.03.6, only beach -compatible, sandy sediments would be used for this project in
accordance with the North Carolina sediment compatibility rules. Dredging of sandy
sediments would minimize the amount of turbidity and sedimentation associated with the
dredging operation and would reduce the suspension time and advection distance of
overflow sediments.
• 8.03.3.3 Sediment Compatibility (pe. 200)
The compatibility analysis compared the grain size of the native beach or the reference
beach with the material in the proposed borrow areas. The overfill ratio is the primary
indicator of the compatibility of the borrow material to the beach material, with a value of
1.00 indicating that one cubic yard of borrow material is needed to match one cubic yard
of beach material. An overfill ratio of up to 1.5 is generally considered acceptable as a

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
July 2013
match of compatibility. The procedure for calculating the overfill ratio for borrow areas
in relation to the reference beach was performed in accordance with the Corps Coastal
and Hydraulics Laboratory Automated Coastal Engineering System (ACES) software
version 4.01.
• 11.03 Fish and Wildlife Coordination (m. 243)
5. USFWS Recommendation: If beach construction is ultimately undertaken, the fill
material should have a high degree of compatibility with the native beach. The North
Carolina Sediment Criteria Rule, contained in the Technical Standards for Beach fill
Projects (15A NCAC 07H .0312), should be used in regard to grain size and percent
weight of calcium carbonate. In addition, compatibility should be established for other
important characteristics such as organic content, heavy mineral content, and color.
Corps Response: The proposed borrow area sediments for this project would comply
with grain size and percent weight requirements specified in 15A NCAC 07H .0312,
Technical Standards for Beachfill Projects. The technical standards require compatibility
of the native beach with borrow sources in regards to the percentage of silt, granular
sediment, gravel, and calcium carbonate (or shell content for projects initiated before
implementation of the rules). However, no federal or state requirements exist for
compatibility in regards to organic content, heavy mineral content, or color. Therefore, a
compatibility analysis for those items would not be conducted. The standards require that
percent silt, granular sediment, and gravel in borrow material not exceed the amount
found in the native beach plus 5 percent and the percent carbonate in borrow material not
exceed the amount found in the native beach plus 15 percent. The silt, granular sediment,
gravel content, and visual shell content for the Surf City/North Topsail Beach project are
1.2, 1.1, 0.5, and 9 percent respectively. Incorporating the tolerance permitted by the
beach fill standards results in the following criteria: silt (6.2 percent), granular sediment
(6.1 percent), gravel (5.5 percent), and calcium carbonate (24 percent). On the basis of
current vibracore data, borrow areas A, F, L, S, and P exceed the standards for various
characteristics. However, during the PED phase of the project additional borings or
geophysical surveys would be performed to better delineate the borrow area boundaries
and material types, with respect to the state sediment criteria rule, to ensure compatibility
of beach fill material before placement. Because that additional analysis was included
during PED, the borrow areas have been retained for further characterization. Before
initial construction and each nourishment event, all material dredged for placement on the
beach would comply with the sediment criteria rule.
• Appendix T —Public Comments and USACE Responses
NC State Consistency Concurrence
5. COMMENT SOURCE: Public/State Consistency

Environmental Assessment
West Onslow Beach and New River Inlet (Topsail Beach) and Surf City and North
Topsail Beach Coastal Storm Damage Reduction Projects
COMMENT: Only beach quality sand shall be used for this project. Should the dredging
operations encounter sand deemed non -compatible with native grain size or sorting
characteristics of the native beach, the dredge operator shall immediately cease operation
and contact the DCM. Dredge operations will resume only after resolution of the issue of
sand compatibility is achieved. f
RESPONSE: Concur. Table 7.1 (Project Commitments) incorporates these commitments
for assurance of sediment compatibility.
North Carolina Division of Coastal Management (NCDCM) — Letter dated April 16,
2010
Subject: CD10-017- Consistency Concurrence for Proposed Implementation of the
Integrated Feasibility Report and EIS Regarding Coastal Storm Damage Reduction at
Surf City and North Topsail Beach, Onslow and Pender Counties, NC (DCM#20100006)
Only beach quality sand shall be used for this project. Should the dredging
operations encounter sand deemed non -compatible with the native grain size or
sorting characteristics of the native beach, the dredge operator shall immediately
cease operation and contact the DCM. Dredge operations will resume only after the
issue of sand compatibility is resolved.