HomeMy WebLinkAboutSW8060338_HISTORICAL FILE_20090330STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO
SW8 MD033g
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
2_00c5 03')O
YYYYMMDD
4
NCDENRt
North Carolina Department of Environment and Natural Resources �\
Beverly Eaves Perdue
Governor
March 30, 2009
Mr Sheldon Tucker, Manager
Ocean Isle Palms, LLC
131 Ocean Blvd West
Holden Beach, NC 28462
Division of Water Quality
Colleen H Sullins
Director
Subject Stormwater Permit No SW8 060338 MOD
Ocean Isle Palms Phase 1
High Density Subdivision Project
Brunswick County
Dear Mr Tucker
ro
Dee Freeman
Secretary
The Wilmington Regional Office received a modified Stormwater Management Permit
application for Ocean Isle Palms Phase 1 on March 30, 2009 Staff review of the plans and
specifications has determined that the project, as proposed, will comply with the Stormwater
Regulations set forth in Title 15A NCAC 2H 1000 We are forwarding Permit No SW8 060338
MOD, dated March 30, 2009, for the construction of the project, Ocean Isle Palms Phase 1
This permit shall be effective from the date of issuance until November 29, 2017, and shall be
subject to the conditions and limitations as specified therein Please pay special attention to the
Operation and Maintenance requirements in this permit Failure to establish an adequate
system for operation and maintenance of the stormwater management system will result in
future compliance problems
If any parts, requirements, or limitations contained in this permit are unacceptable, you have the
right to request an adludicatory hearing upon written request within thirty (30) days following
receipt of this permit This request must be in the form of a written petition, conforming to
Chapter 150E of the North Carolina General Statutes, and filed with the Office of Administrative
Hearings, P O Drawer 27447, Raleigh, NC 27611-7447 Unless such demands are made this
permit shall be final and binding
Please replace sheets SW-3 and C-13 from the plan set approved on November 29, 2007, with
new ones, attached If you have any questions, or need additional information concerning this
matter, please contact Linda Lewis or me at (910) 796-7215
Sincerely,
eorgett Scott
Stormwater Supervisor
Division of Water Quality
GDS/arl S \WQS\STORMWATER\PERMIT\060338MOD mar09
cc Perry Davis, P E , Cape Fear Engineering
Ocean Isle Beach Building Inspections
Jeff Phillips, Brunswick County Engineering
Wilmington Regional Office
Linda Lewis
Central Files
Wilmington Regional Office
127 Cardinal Drive Extension Wilmington North Carolina 28405 One
Phone 910 796 7215 1 FAX 910 350 2004 \ Customer Service 1-877-623-6748 NorthCarolma
Internet w ncwaterqualltyorg
atura!!ff
An Equal Opportunity 1 Aftinnative Action Employer
State Stormwater Management Systems
Permit No SW8 060338MOD
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
STATE STORMWATER MANAGEMENT PERMIT
HIGH DENSITY SUBDIVISION DEVELOPMENT
In accordance with the provisions of Article 21 of Chapter 143, General Statutes of
North Carolina as amended, and other applicable Laws, Rules, and Regulations
PERMISSION IS HEREBY GRANTED TO
Sheldon Tucker & Ocean Isle Palms, LLC
Ocean Isle Palms Phase 1
1338 Ocean Isle Beach Road, Ocean Isle Beach, Brunswick County
FOR THE
construction, operation and maintenance of three (3) wet detention pond(s) in
compliance with the provisions of 15A NCAC 2H 1000 (hereafter referred to as the
"stormwater rules') and the approved stormwater management plans and specifications
and other supporting data as attached and on file with and approved by the Division of
Water Quality and considered a part of this permit
This permit shall be effective from the date of issuance until November 29, 2017 and
shall be subject to the following specified conditions and limitations
I DESIGN STANDARDS
1 This permit is effective only with respect to the nature and volume of stormwater
described in the application and other supporting data
2 This stormwater system has been approved for the management of stormwater 2 \F3
runoff as described in Section 16 on page 3 of this permit The subdivision is
permitted for 230 lots, each allowed a maximum of 6,000 square feet of built -
upon area The Amenity Center and Canoe and Kayak Club are limited to a
maximum of 93,654 square feet and 2,614 square feet, respectively, of built -upon
area
3 Approved plans and specifications for this project are incorporated by reference
and are enforceable parts of the permit
4 The runoff from all built -upon area within the permitted drainage area of this
project must be directed into the permitted stormwater control system
Each of the ponds is designed for 90% TSS removal, therefore, no vegetated
filter is required
Page 2 of 9
State Stormwater Management Systems "
Permit No SW8 060338MOD
6 The following design elements have been permitted for the wet detention ponds
12, 14 and 21, and must be provided in the system at all times
Design Criteria
Pond #12
Pond #14
Pond #21
a Drainage Area acres
Onsite ftZ
Offsite, ftZ
2482
1 081 159
0
51 27
2,233 321
0
21 16
921 730
0
b Total Impervious Surfaces, ft
(#)Lots at 6,000 ftZ per lot
Roads/Parking ftZ
Sidewalks ftZ
Alleyways, ftZ
Canoe & Kayak Club
Amenity Center ftZ
545,930
(74)444 000
95,396
871
3 049
2,614
0
1 127,188
(121)726 000
279,220
0
121 968
0
0
483,992
(35)210 000
158,558
0
21 780
0
93 654
c Pond Depth, ft
Average Pond Depth, ft
60
50
13 0
70
14 0 (max)
55
d TSS removal efficient %
90
90
90
e Design Storm, inches
1
1
1
f Permanent Pool Elev FMSL
3600
800
600
Perm Pool Surface Area, ft
95,110 1
50,491
50,795
h Permitted Storage Volume ft
204 215
108,618
63 553
i Temporary Storage Elev, , FMSL
3800
990
7 10
Controlling Onfice, D i e
3
4
3
k Permanent Pool Volume ft
484 740
359 604
280,903
1 Permitted Forebay Volume ft
45 512
59 124
62,416
m Maximum Fountain Horsepower
2
1
1
n Receiving Stream/River Basin
UT to Jenny's Branch / Lumber
o Stream Index Number
15-25-2-16-1-(1)
Classification of Water Body
C Sw
II SCHEDULE OF COMPLIANCE
No person or other legal entity shall alter the approved stormwater management
system or fill in, alter or pipe any drainage feature, including swales, shown on
the approved plans as part of the stormwater management system, unless and
until the permittee submits a modification to the permit and receives approval
from the Division
2 The permittee is responsible for verifying that the proposed built -upon area on
each individual lot, and for the entire project, does not exceed the maximum
allowed by this permit
The maximum built -upon area assigned to each lot via this permit and the
recorded deed restrictions may not be increased or decreased by or with the
knowledge of, either the lot owner or the permittee, unless and until the permittee
notifies the Division and obtains written approval from the Division At a
minimum, this will require an amendment to the recorded deed restrictions, and
may also require a permit modification
4 If the permittee establishes an Architectural Review Board or Committee to
review plans for compliance with the Covenants and Restrictions, including the
lot BUA limit, the plans reviewed must include all proposed built -upon area on
that lot Any approval given by the Board on behalf of the permittee does not
relieve the permittee of the responsibility to maintain compliance with the overall
permitted built -upon area for the project, nor does it relieve the individual lot
owner of the responsibility to maintain compliance with the BUA limit assigned to
that lot via the recorded deed restrictions
Page 3 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
5 The Director may notify the permittee when the permitted site does not meet one
or more of the minimum requirements of the permit Within the time frame
specified in the notice, the permittee shall submit a written time schedule to the
Director for modifying the site to meet minimum requirements The permittee
shall provide copies of revised plans and certification in writing to the Director
that the changes have been made
6 The stormwater management system shall be constructed in its entirety,
vegetated and operational for its intended use prior to the construction of any
built -upon surface
The permittee shall submit to the Director and shall have received approval for
revised plans, specifications, and calculations prior to construction, for any
modification to the approved plans, including, but not limited to, those listed
below
Any revision to the approved plans, regardless of size
Project name change
Transfer of ownership
Redesign or addition to the approved amount of built -upon area
Further subdivision, acquisition, or sale of all or part of the project area
The project area is defined as all property owned by the permittee, for
which Sedimentation and Erosion Control Plan approval or a CAMA Major
permit was sought
Filling in, altering, or piping of any vegetative conveyance shown on the
approved plan
8 The Director may determine that other revisions to the project should require a
modification to the permit
9 All stormwater collection and treatment systems must be located in either
dedicated common areas or recorded easements The final plats for the project
will be recorded showing all such required easements, in accordance with the
approved plans
10 During construction, erosion shall be kept to a minimum and any eroded areas of
the system will be repaired immediately
11 Upon completion of construction, prior to issuance of a Certificate of Occupancy,
and prior to operation of this permitted facility, a certification must be received
from an appropriate designer for the system installed certifying that the permitted
facility has been installed in accordance with this permit, the approved plans and
specifications, and other supporting documentation Any deviations from the
approved plans and specifications must be noted on the Certification
12 If the stormwater system was used as an Erosion Control device, it must be
restored to design condition prior to operation as a stormwater treatment device,
and prior to occupancy of the facility
13 Permanent seeding requirements for the stormwater control must follow the
guidelines established in the North Carolina Erosion and Sediment Control
Planning and Design Manual
Page 4 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
14 The permittee shall at all times provide the operation and maintenance
necessary to assure that all components of the permitted stormwater system
function at optimum efficiency The approved Operation and Maintenance Plan
must be followed in its entirety and maintenance must occur at the scheduled
intervals including, but not limited to
a Semiannual scheduled inspections (every 6 months)
b Sediment removal
c Mowing and re -vegetation of side slopes
d Immediate repair of eroded areas
e Maintenance of side slopes in accordance with approved plans and
specifications
f Debris removal and unclogging of structures, orifice, catch basins and
piping
g Access to all components of the system must be available at all times
15 Records of maintenance activities must be kept and made available upon
request to authorized personnel of DWQ The records will indicate the date,
activity, name of person performing the work and what actions were taken
16 This permit shall become void unless the facilities are constructed in accordance
with the conditions of this permit, the approved plans and specifications, and
other supporting data
17 Prior to the sale of any lot, the following deed restrictions must be recorded
a The following covenants are intended to ensure ongoing compliance with
State Stormwater Management Permit Number SW8 060338MOD, as
issued by the Division of Water Quality under NCAC 2H 1000
b The State of North Carolina is made a beneficiary of these covenants to
the extent necessary to maintain compliance with the Stormwater
Management Permit
c These covenants are to run with the land and be binding on all persons
and parties claiming under them
d The covenants pertaining to stormwater may not be altered or rescinded
without the express written consent of the State of North Carolina, Division
of Water Quality
e Alteration of the drainage as shown on the approved plans may not take
place without the concurrence of the Division of Water Quality
f The maximum built -upon area per lot is 6,000 square feet This allotted
amount includes any built -upon area constructed within the lot property
boundaries, and that portion of the right-of-way between the front lot line
and the edge of the pavement Built upon area includes, but is not limited
to, structures, asphalt, concrete, gravel, brick, stone, slate, coquina and
parking areas, but does not include raised, open wood decking, or the
water surface of swimming pools
g All runoff on the lot must drain into the permitted system This may be
accomplished through providing roof dram gutters, which drain to the
street, grading the lot to drain toward the street, or grading perimeter
swales and directing them into the pond or street Lots that will naturally
drain into the system are not required to provide these measures
h Built -upon area in excess of the permitted amount will require a permit
modification
18 A copy of the recorded deed restrictions must be submitted to the Division within
30 days of the date of recording the plat, and prior to selling lots The recorded
copy must contain all of the statements above, the signature of the Permittee, the
deed book number and page, and the stamp/signature of the Register of Deeds
Page 5 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
19 Prior to transfer of the permit, the stormwater facilities will be inspected by DWQ
personnel The facility must be in compliance with all permit conditions Any
items not in compliance must be repaired or replaced to design condition prior to
the transfer Records of maintenance activities performed to date will be
required
20 Decorative spray fountains will be allowed in the stormwater treatment system,
subject to the following criteria
a The fountain must draw its water from less than 2' below the permanent
pool surface
b Separated units, where the nozzle, pump and intake are connected by
tubing, may be used only if they draw water from the surface in the deepest
part of the pond
c The falling water from the fountain must be centered in the pond, away from
the shoreline
d The maximum horsepower for the fountain's pump is based on the
permanent pool volume The maximum pump power for a fountain in Pond
#12, 14, and 21 is 2 HP, 1 HP, and 1 HP, respectively
III GENERAL CONDITIONS
This permit is not transferable to any person or entity except after notice to and
approval by the Director In the event there is either a desire for the facilities to
change ownership, or there is a name change of the Permittee, a completed
"Name/Ownership Change Form" must be submitted to the Division of Water
Quality, signed by the parties involved, along with the applicable documents as
listed on page 2 of the form The project must be in good standing with DWQ
The approval of this request will be considered on its merits and may or may not
be approved
2 The permittee is responsible for compliance with all of the terms and conditions
of this permit until such time as the Director approves the transfer request
3 Failure to abide by the conditions and limitations contained in this permit may
subject the Permittee to enforcement action by the Division of Water Quality, in
accordance with North Carolina General Statute 143-215 6A to 143-215 6C
4 The issuance of this permit does not preclude the Permittee from complying with
any and all statutes, rules, regulations, or ordinances, which may be imposed by
other government agencies (local, state, and federal), which have jurisdiction
5 In the event that the facilities fad to perform satisfactorily, including but not limited
to, the creation of nuisance conditions and failing to draw down within 2-5 days,
the Permittee shall take immediate corrective action, including those as may be
required by this Division, such as the construction of additional or replacement
stormwater management systems
6 The permit may be modified, revoked and reissued or terminated for cause The
filing of a request for a permit modification, revocation and re -issuance or
termination does not stay any permit condition
7 Permittee grants permission to staff of the DWQ to access the property for the
purposes of inspecting the stormwater facilities during normal business hours
8 The permittee shall notify the Division in writing of any name, ownership or
mailing address changes at least 30 days prior to making such changes
Page 6 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
9 The permittee shall submit a permit renewal application to the Division at least
180 days prior to the expiration date of this permit The renewal application will
include the processing fee and other documentation as required
10 A copy of the approved plans and specifications shall be maintained on file by
the Permittee for a minimum of ten years from the date of the completion of
construction
Permit modified and reissued this the 30th day of March 2009
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
By Authority of the Environmental Management Commission
Permit Number SW8 060338MOD
Page 7 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
Ocean Isle Palms Phase 1 Page 1 of 2
Stormwater Permit No SW8 060338MOD
Brunswick Countv
Designer's Certification
I, , as a duly registered in
the State of North Carolina, having been authorized to observe (periodically/weekly/full
time) the construction of the project,
(Protect)
for (Protect Owner) hereby state that, to the
best of my abilities, due care and diligence was used in the observation of the protect
construction such that the construction was observed to be built within substantial
compliance and intent of the approved plans and specifications
The checklist of items on page 2 of this form is a part of this Certification
Noted deviations from approved plans and specifications
Signature
Registration Number
Date
SEAL
Page 8 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
Certification Requirements
Page 2 of 2
1 The drainage area to the system contains approximately the permitted
acreage
2 The drainage area to the system contains no more than the permitted
amount of built -upon area
3 All the built -upon area associated with the project is graded such that the
runoff drains to the system
4 All roof drains are located such that the runoff is directed into the system
5 The outlet/bypass structure elevations are per the approved plan
6 The outlet structure is located per the approved plans
7 Trash rack is provided on the outlet/bypass structure
8 All slopes are grassed with permanent vegetation
9 Vegetated slopes are no steeper than 3 1
10 The inlets are located per the approved plans and do not cause short-
circuiting of the system
11 The permitted amounts of surface area and/or volume have been
provided
12 Required drawdown devices are correctly sized per the approved plans
13 All required design depths are provided
14 All required parts of the system are provided, such as a vegetated shelf, a
forebay, and the vegetated filter
15 The required dimensions of the system are provided, per the approved
plan
cc NCDENR-DWQ Regional Office
Brunswick County Budding Inspections
Page 9 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
STATE STORMWATER MANAGEMENT PERMIT
HIGH DENSITY SUBDIVISION DEVELOPMENT
In accordance with the provisions of Article 21 of Chapter 143, General Statutes of
North Carolina as amended, and other applicable Laws, Rules, and Regulations
PERMISSION IS HEREBY GRANTED TO
Sheldon Tucker & Ocean Isle Palms, LLC
Ocean Isle Palms Phase 1
1338 Ocean Isle Beach Road, Ocean Isle Beach, Brunswick County
FOR THE
construction, operation and maintenance of three (3) wet detention pond(s) in
compliance with the provisions of 15A NCAC 2H 1000 (hereafter referred to as the
"stormwater rules') and the approved stormwater management plans and specifications
and other supporting data as attached and on file with and approved by the Division of
Water Quality and considered a part of this permit
This permit shall be effective from the date of issuance until November 29, 2017 and
shall be subject to the following specified conditions and limitations
I DESIGN STANDARDS
This permit is effective only with respect to the nature and volume of stormwater
described in the application and other supporting data
This stormwater system has been approved for the management of stormwater
runoff as described in Section 16 on page 3 of this permit The subdivision is �011
permitted for 230 lots, each allowed a maximum of 6,000 square feet of built- 4
upon area The Amenity Center and Canoe and Kayak Club are limited to a a
maximum of 93,654 square feet and 2,614 square feet, respectively, of built-uponoo�
area
Approved plans and specifications for this project are incorporated by reference
and are enforceable parts of the permit
4 The runoff from all built -upon area within the permitted drainage area of this
project must be directed into the permitted stormwater control system
5 Each of the ponds is designed for 90% TSS removal, therefore, no vegetated
filter is required
Page 2 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
6 The following design elements have been permitted for the wet detention ponds
12, 14 and 21, and must be provided in the system at all times 6
Design Criteria
Pond #12
Pond #14
Pond #21
a Drainage Area, acres
2482
51 27
21 16
Onsite, ft2
1,081159
2-233,321
ft2
0
0�
0921,730�—,��Offsde,
b Total Impervious Surfaces ft2
(-545 930
i1,127,188
_' 83,992�
(#)Lots at 6,000 ft2 per lot
(74)444,000
(121)726,000
(35)210,000
Roads/Parking ft2
95 396
279,220
158 558
Sidewalks, ft2
871
0
0
Alleyways, ft2
3,049
121 968
21,780
Canoe & Kayak Club
2,614
0
Amenity Center, ft2
0
q CUAeo
93,654
c Pond Depth ft
60
130
14 0 (max)
Average Pond Depth, ft
50
70
55
d TSS removal efficiency, %
90
90
90
e Design Storm, inches
1
1
1
f Permanent Pool Elev FMSL
3600
800
600 -
Perm Pool Surface Area, ft
95 110
50 491
50,795
h Permitted Storage Volume ft
204 215
108,618
63 553
i Temporary Storage Elev , FMSL
3800
990
710
Controlling Orifice, "Op'e
3
4
3
k Permanent Pool Volume, ft
484,740
359,604
1280 903
1 Permitted Forebay Volume, ftJ
45,512
59,124
1 62,416
m Maximum Fountain Horsepower
2
1
1 1
n Receiving Stream/River Basin
UT to Jinny's Branch / Lumber
o Stream Index Number
15-25-2-16-1-(1)
Classification of Water Body
C Sw
II SCHEDULE OF COMPLIANCE
No person or other legal entity shall alter the approved stormwater management
system or fill in, alter or pipe any drainage feature, Including swales, shown on
the approved plans as part of the stormwater management system, unless and
until the permittee submits a modification to the permit and receives approval
from the Division
2 The permittee is responsible for verifying that the proposed built -upon area on
each Individual lot, and for the entire project, does not exceed the maximum
allowed by this permit
3 The maximum built -upon area assigned to each lot via this permit and the
recorded deed restrictions may not be Increased or decreased by or with the
knowledge of, either the lot owner or the permittee, unless and until the permittee
notifies the Division and obtains written approval from the Division At a
minimum, this will require an amendment to the recorded deed restrictions, and
may also require a permit modification
4 If the permittee establishes an Architectural Review Board or Committee to
review plans for compliance with the Covenants and Restrictions, including the
lot BUA limit, the plans reviewed must include all proposed built -upon area on
that lot Any approval given by the Board on behalf of the permittee does not
relieve the permittee of the responsibility to maintain compliance with the overall
permitted built -upon area for the project, nor does it relieve the individual lot
owner of the responsibility to maintain compliance with the BUA limit assigned to
that lot via the recorded deed restrictions
Page 3 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
5 The Director may notify the permittee when the permitted site does not meet one
or more of the minimum requirements of the permit Within the time frame
specified in the notice, the permittee shall submit a written time schedule to the
Director for modifying the site to meet minimum requirements The permittee
shall provide copies of revised plans and certification in writing to the Director
that the changes have been made
6 The stormwater management system shall be constructed in its entirety,
vegetated and operational for its intended use prior to the construction of any
built -upon surface
7 The permittee shall submit to the Director and shall have received approval for
revised plans, specifications, and calculations prior to construction, for any
modification to the approved plans, including, but not limited to, those listed
below
a Any revision to the approved plans, regardless of size
b Project name change
c Transfer of ownership
d Redesign or addition to the approved amount of built -upon area
e Further subdivision, acquisition, or sale of all or part of the project area
The project area is defined as all property owned by the permittee, for
which Sedimentation and Erosion Control Plan approval or a CAMA Major
permit was sought
f Filling in, altering, or piping of any vegetative conveyance shown on the
approved plan
8 The Director may determine that other revisions to the project should require a
modification to the permit
9 All stormwater collection and treatment systems must be located in either
dedicated common areas or recorded easements The final plats for the project
will be recorded showing all such required easements, in accordance with the
approved plans
10 During construction, erosion shall be kept to a minimum and any eroded areas of
the system will be repaired immediately
11 Upon completion of construction, prior to issuance of a Certificate of Occupancy,
and prior to operation of this permitted facility, a certification must be received
from an appropriate designer for the system installed certifying that the permitted
facility has been installed in accordance with this permit, the approved plans and
specifications, and other supporting documentation Any deviations from the
approved plans and specifications must be noted on the Certification
12 If the stormwater system was used as an Erosion Control device, it must be
restored to design condition prior to operation as a stormwater treatment device,
and prior to occupancy of the facility
13 Permanent seeding requirements for the stormwater control must follow the
guidelines established in the North Carolina Erosion and Sediment Control
Planning and Design Manual
Page 4 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
14 The permittee shall at all times provide the operation and maintenance
necessary to assure that all components of the permitted stormwater system
function at optimum efficiency The approved Operation and Maintenance Plan
must be followed in its entirety and maintenance must occur at the scheduled
intervals including, but not limited to
a Semiannual scheduled inspections (every 6 months)
b Sediment removal
c Mowing and re -vegetation of side slopes
d Immediate repair of eroded areas
e Maintenance of side slopes in accordance with approved plans and
specifications
f Debris removal and unclogging of structures, orifice, catch basins and
piping
g Access to all components of the system must be available at all times
15 Records of maintenance activities must be kept and made available upon
request to authorized personnel of DWQ The records will indicate the date,
activity, name of person performing the work and what actions were taken
16 This permit shall become void unless the facilities are constructed in accordance
with the conditions of this permit, the approved plans and specifications, and
other supporting data
17 Prior to the sale of any lot, the following deed restrictions must be recorded
a The following covenants are intended to ensure ongoing compliance with
State Stormwater Management Permit Number SW8 060338MOD, as
issued by the Division of Water Quality under NCAC 2H 1000
b The State of North Carolina is made a beneficiary of these covenants to
the extent necessary to maintain compliance with the Stormwater
Management Permit
c These covenants are to run with the land and be binding on all persons
and parties claiming under them
d The covenants pertaining to stormwater may not be altered or rescinded
without the express written consent of the State of North Carolina, Division
of Water Quality
e Alteration of the drainage as shown on the approved plans may not take
place without the concurrence of the Division of Water Quality
f The maximum built -upon area per lot is 6,000 square feet This allotted �w a
amount includes any built -upon area constructed within the lot property
boundaries, and that portion of the right-of-way between the front lot line Act,
and the edge of the pavement Built upon area includes, but is not limited (No°
to, structures, asphalt, concrete, gravel, brick, stone, slate, coquina and
parking areas, but does not include raised, open wood decking, or the
water surface of swimming pools
g All runoff on the lot must dram into the permitted system This may be
accomplished through providing roof drain gutters, which drain to the
street, grading the lot to drain toward the street, or grading perimeter
swales and directing them into the pond or street Lots that will naturally
drain into the system are not required to provide these measures
h Built -upon area in excess of the permitted amount will require a permit
modification
18 A copy of the recorded deed restrictions must be submitted to the Division within
30 days of the date of recording the plat, and prior to selling lots The recorded
copy must contain all of the statements above, the signature of the Permittee, the
deed book number and page, and the stamp/signature of the Register of Deeds
Page 5 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
19 Prior to transfer of the permit, the stormwater facilities will be inspected by DWQ
personnel The facility must be in compliance with all permit conditions Any
items not in compliance must be repaired or replaced to design condition prior to
the transfer Records of maintenance activities performed to date will be
required
20 Decorative spray fountains will be allowed in the stormwater treatment system,
subject to the following criteria
a The fountain must draw its water from less than 2' below the permanent
pool surface
b Separated units, where the nozzle, pump and intake are connected by
tubing, may be used only if they draw water from the surface in the deepest
part of the pond
c The falling water from the fountain must be centered in the pond, away from
the shoreline
d The maximum horsepower for the fountain's pump is based on the
permanent pool volume The maximum pump power for a fountain in Pond
#12, 14, and 21 is 2 HP, 1 HP, and 1 HP, respectively
III GENERAL CONDITIONS
This permit is not transferable to any person or entity except after notice to and
approval by the Director In the event there is either a desire for the facilities to
change ownership, or there is a name change of the Permittee, a completed
"Name/Ownership Change Form" must be submitted to the Division of Water
Quality, signed by the parties involved, along with the applicable documents as
listed on page 2 of the form The project must be in good standing with DWQ
The approval of this request will be considered on its merits and may or may not
be approved
2 The permittee is responsible for compliance with all of the terms and conditions
of this permit until such time as the Director approves the transfer request
Failure to abide by the conditions and limitations contained in this permit may
subject the Permittee to enforcement action by the Division of Water Quality, in
accordance with North Carolina General Statute 143-215 6A to 143-215 6C
4 The issuance of this permit does not preclude the Permittee from complying with
any and all statutes, rules, regulations, or ordinances, which may be imposed by
other government agencies (local, state, and federal), which have jurisdiction
In the event that the facilities fad to perform satisfactorily, including but not limited
to, the creation of nuisance conditions and failing to draw down within 2-5 days,
the Permittee shall take immediate corrective action, including those as may be
required by this Division, such as the construction of additional or replacement
stormwater management systems
6 The permit may be modified, revoked and reissued or terminated for cause The
filing of a request for a permit modification, revocation and re -issuance or
termination does not stay any permit condition
7 Permittee grants permission to staff of the DWQ to access the property for the
purposes of inspecting the stormwater facilities during normal business hours
8 The permittee shall notify the Division in writing of any name, ownership or
mailing address changes at least 30 days prior to making such changes
Page 6 of 9
State Stormwater Management Systems
Permit No SW8 060338MOD
The permittee shall submit a permit renewal application to the Division at least
180 days prior to the expiration date of this permit The renewal application will
include the processing fee and other documentation as required
10 A copy of the approved plans and specifications shall be maintained on file by
the Permittee for a minimum of ten years from the date of the completion of
construction
Permit modified and reissued this the 30th day of March 2009
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
Division of Water Quality
By Authority of the Environmental Management Commission
Permit Number SW8 060338MOD
Page 7 of 9
I Is
�pE WATg Michael F Easley Governor
`p G WdhamG Ross Jr Sammy
Co
r Nosh Carolina Department of Environment and Natural Resources
,I
p Colan H Sulhro Director
Division of Water Quality
WATER QUALITY SECTION
COASTAL STORMWATER PERMIT NAME/OWNERSHIP CHANGE FORM
I CURRENT PERMIT INFORMATION
1 Stormwater Management Permit Number Sw8 060338
2 Permit Holder's Name Ocean Isle Palms, Inc
3 Signing official's Name Sheldon Tucker Title Secretary
(person legally responsible for penna)
4 Mailing Address 131 ocean Blvd west
City Holden Beach State NC Zip 28462
Phone (910) 612-4899 Fax ( 1
II NEW OWNER / PROJECT / ADDRESS INFORMATION
t This request is for (please check all that apply)
x a Change in ownership of the property/company (Please complete Items #2,
#3, and #4 below)
b Name change of project (Please complete Item #5 below)
c Mailing address change (Please complete Item #4 below)
d Other (please explain)
2 New owner's name to be put on permit ocean Isle Palms, LLC
3 New owners signing official's name and title Sheldon Tucker
Title Manager
4 New Mailing Address 131 ocean Blvd west
City Holden Beach State NC Zip 28462
Phone (910) 612-4899 Fax ( ) __
5 New Project Name to be placed on permit _
Ownership/Name Change 060608 Page 1 Of 3
PERMIT NAME/OWNERSHIP CHANGE FORM
THIS APPLICATION PACKAGE WILL NOT BE ACCEPTED BY THE DIVISION OF WATER
QUALITY UNLESS ALL OF THE APPLICABLE ITEMS LISTED BELOW ARE INCLUDED
WITH THE SUBMITTAL
REQUIRED ITEMS
This completed form
Legal documentation of the transfer of ownership
A copy of the recorded deed restrictions, if required by the permit
The designer's certification, if required by the permit
A signed Operation and Maintenance plan, if a system that requires maintenance will
change ownership
Maintenance records
CERTIFICATION MUST BE COMPLETED AND SIGNED BY BOTH THE CURRENT PERMIT
HOLDER AND TNEISEW APPLICANT IN THE CASE OF A CWME OF OWNERSHIP
FOR NAME CHANGES, COMPLETE AND SIGN ONLY THE CURRENT PERMITTEE'S
CERTIFICATION
Current Permittee's Certification
1, Sheldon Tucker attest that this application for a name/ownership
change has been reviewed and is accurate and complete to the best of my knowledge I
understand that if all required parts of this application are not completed and that if all required
supporting information and attachments are not included, this application package will be
returned as incomplete�/
Signaturev ,% L /yam Date
New Applicant's Certification (Must be completed for all transfers of ownership)
I, Sheldon Tucker attest that this application for an ownership
change has been reviewed and is accurate and complete to the best of my knowledge I
understand that if all required parts of this application are not completed and that if all required
supporting information and attachments are not included, this application package will be
returned as incom e / d
Signature /% Date �� Dv
Mall the entire package to NCDENR Division of Water Quality
Surface Water Protection Section — Stormwater
at the Appropriate Contact Address (see the following page)
PwnershipfName Change-060608 Page 2 of 3
3/3!/67
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P 01
t TRANSACTION REPORT
MAR-31-2009 TUE 02-39 PM t
X �
FOR; NCDENR 910 350 2004
SEND
DATE START RECEIVER TX TIME PAGES TYPE NOTE M# DP
w
t MAR-31 02,37 PM 93831045 1'32" 10 FAX TX OK 343 t
TOTAL ' 1M 32S PAGES 10
State of North Carolina
Department of Environment and Natural Resources
Wilmington Regional Office
Beverly Eaves Perdue, Governor
FAX COVER SHEET
Dee Freeman, Secretary
Date - 31—� No Pages (excl cover) Qj
Express Permitting
To _ Z From Sandra Exum
Co Phone (910) 796-7265
Fax �,�C3,� 1ra�� J Fax (910) 350-2004
Re
Hard copy to follow
127 Cardinal Drive Extension, Wilmington, NC 28405 • (910) 796-7215 • An Equal Opportunely AffirmaAve Aotton Employer
CAPE FEAR
Engineering, Inc.
March 5, 2009
Linda Lewis
Environmental Engineer 111
North Carolina Division of Water Quality
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
RE Ocean Isle Palms — Phase IA & IB
Brunswick County
DWQ Stormwater Permit Number SW8 060338
Plan Revision / Request for Additional Information
Ms Lewis,
MAR 0 9 2009
By
We are submitting a Plan Revision to the above stormwater permit The intention of this plan
revision is to remove the clay liners from the approved pond details
This plan revision was originally submitted to you on April 30, 2008 and subsequently you issued
a Request for Additional Information for this plan revision on July 31, 2008 A copy of your July
31, 2008 request has been included with this submittal
We are aware that the deadline for responding to this request has elapsed, however, we felt it was
pertinent to include this information in order to provide some background on the proposed plan
revision
Since the initial submittal of this plan revision, Cape Fear Engineering has successfully been able
to remove a number of clay liners from ponds in other projects by demonstration that the
influence of the SHWT is negligible and does not compromise the ponds functioning
The same engineering procedure has been applied to this project and it too shows that removal of
the clay liners does not compromise the functioning of the ponds The complete Engineer's
Report that describes and details this procedure has been included with this submittal
Additionally, revised plan sheets Phase IA C-13 and Phase 113 SW-3 have been included in this
submittal Please replace the previously approved plan sheets upon approval of this plan revision
I trust that this information is sufficient to issue this plan revision for the subject stormwater
permit, however, if you have any questions or need any additional information please do not
hesitate to contact me
Respectfully,
Matthew Haley, E I
151 Poole Road 5uite 100 • 6elvi11e,NC243451 • ?EL (910)363-1044 • FAX (910)363 1045
wwwcapefearengineering cam
CAPE FEAR
Engineering, Inc.
151 Poole Road SuAe 1 W
BeMlle NC 28C5/
TEL (8/0)388-10
FAX (810) 383�IN5
www capefearenglneermg com
To
NC DWQ Surface Water Protection
State Stormwater Section
127 Cardinal Drive Ext
Wilmington, NC 28405
Attn
Linda Lewis
ZOO MAR D 9 2009
Transmittal
Date March 9, 2009
File 809-02 "36"
Subject Ocean Isle Palms Phase 1A & 1B
(SW8 060338)
Plan Revision — Removal of Clay Liners
❑ As Requested ❑ For Your Files ❑ For Distribution ® For your Review / Action / Approval
❑ Sent via Mail ❑ Sent via Courier
Quantity
Drawing No
Description
1
Original
Cover Letter
1
Copy
Request for Additional Information Letter
1
Copy
Engineer's Report (Including Figures and FEMA FIRM Panels)
3
Copy
Revised Plan Sheets Phase 1A C-13 and Phase I SW-3
InJWV7ft5
MAR 09 2009
BY
REMARKS Please find the requested information regarding the plan revision to remove the previously permitted
clay liners If you have any questions or need any additional information please contact me directly
Thanks
CC File 809-02 "36"
Cape Fear Engineering, In
Signed WLS
Matthew Haley EV
Received By
Date
P \809\809 02\Wdinin\ST0RM WTR\Trans Linda Lewis 3 9 09 doe
RECVVE
MAY 0 B Z669
Stormwater Desi arrative & Calcu
For
Ocean Isle Palms
Phase 1 Modification
May 2009
OCEAN ISLE PALMS
Brunswick County, North Carolina
CAPE FEAR
Engineering, Inc.
151 Pole Rwd Surte 100
BeMW NC 28451
TEL (910) W8 10
W (910) 8 10
www capefeareng/neering com
MAY 0 8 g00g
DESIGN NARRATIVE
General:
The Ocean Isle Palms project is located off Ocean Isle Beach Road (SR 1184), approximately'/<
mile south of the intersection of Ocean Isle Beach Road and Georgetown Road (SR 1163) within
Brunswick County, North Carolina Ocean Isle Palms Phase IA and 1B is a high density
development and consists of approximately 114 45 acres A stormwater permit was issued for
Ocean Isle Palms Phase 1 as SW8 060338MOD on 11/29/07 A plan revision to remove the clay
liners from Ponds 14 and 21 was issued on 4/2/09
As requested, the total impervious area allocation for each pond has been reviewed and revised to
reflect the current plan Revised applications and calculations have been provided
The current proposal consists of increasing the size of the drainage area associated with Pond 21
The pond configuration has been modified to remove the previously permitted onfice, which has
been replaced with an outlet structure —
Proposed improvements within this phase of development include streets, parking, sidewalks,
drainage improvements, residential lots, and amenities Pond 21 is currently designed to treat
stormwater runoff from 43 5 single family home sites and an amenity center
The modified Pond 21 is designed for 90% TSS removal and has been sized to attenuate the peak
discharge for the 1-year and 10-year 24-hour storm events
Existing Site:
The project site is the location a former golf course and is primarily wooded with some open
space Soils onsite are comprised primarily HSG C and D soils according to the Brunswick
County Soil Survey Site topography in the area is relatively flat with slopes typically less than
four percent, but exceeding four percent in small areas adjacent to the wetlands and Jinnys
Branch (C Sw, HQW, 15-25-2-16-1-(1 5)) The general gradient is from north to south toward
Jinnys Branch
Vegetation consists primarily of thick underbrush and grasses with mature pines and hardwoods
in the wooded areas
Wetlands have been delineated and this delineation is reflected on the site plans The USACE
field verified the delineation and a map has been submitted for signature
Proposed Improvements:
Proposed improvements include drainage devices, streets, and utilities Drainage for the most
part will sheet flow from the homesrtes into the streets The typical road section will employee
curb and gutter to direct drainage to low points in the roads Drainage from the low points will
flow into pipe network system, which will discharge into Amenity Pond 22 The outflow from
Amenity Pond 22 will flow into the pipe network system that eventually discharges to Pond 21
Drainage Considerations:
xUlfC
MAY 0 8 P009
BY
All impervious drainage from the project site will be captured in an engineered system of curbed
and guttered streets with piped systems or curb outlets that will convey stormwater to the wet
detention pond
Erosion Control Considerations:
Silt fence, wire and gravel inlet protection and inlet sumps will be employed to retain all
sediment on -site
Maintenance Considerations:
During construction, the Contractor shall be required to inspect and repair as needed all erosion
control devices after any significant ram event Any measure found not performing its intended
function, shall be repaired immediately Upon completion of construction the establishment of
permanent ground cover will be a priority
DRAINAGE AREA (Ad) _
IMPERVIOUS AREA (A0
WET DETENTION BASIN DATA SHEET
OCEAN ISLE PALMS PHASE I A
POND #12
24 82 ACRES ✓��
(09.5
REC i ,�--
MAY 0 S 2009
BY =
BUILDINGS 10 19 ACRES = >'LOTS @ 0000 SF/LOT
ROADS 2 19 ACRES (+ FUToKe
SIDEWALKS 0 02 ACRES ToTnt y 3) 87-7
SF
C*K CLUB 0 OG ACRES Q
CONTINGENCY 0 07 ACRES ALLEY WAYS 51�I�
TOTAL 12 53 ACRES,/
PERCENT IMPERVIOUS (1)
I = Ad/Ai = 50 47%
POND # 12 SHALL BE 0' DEEP WITH
AN AVG DEPTH Of 5' AND DESIGNED TO REMOVE 30% T55
5A/DA= 3 54% 1
REQUIRED SURFACE AREA AT PERMANENT POOL
SAREQ = 0 8778834 AC = 3524 I 5P
SURFACE AREA PROVIDED AT PERMANENT POOL (EL 3G)= 951 1 Ov/SP
. .. . .. .. .. . . .. ... .. . . . . .
5A PROV'D= 951 10 > 35241 =5A REQ'D OK
MINIMUM REQUIRED VOLUME (SIMPLE METHOD BYTOM SCHUELER)
Rv=O 05+0 009T)
Rv= 050423
VOLUME= I "'Rv`Ad =
Rv= (0 05+0 009-50 47)
1 04292 AC -FT
45420 FT ^ 3
VOLUME PROVIDED AT TEMPORARY POOL
INCREM
TOTAL
El
SA F)
VOL (CF)
VOL. (CF)
3G`/
✓95110
0
0
37
103170
991 39 9
99 139 9
38
10G075
105075
204215
39
110845
106912
313127
40 1147GG
41 123174
112605 425932
118970 544502
5ET TEMP POOL ELEVATION
REQ'D EL = 3G 4G F SAY 38 00'
VOL PROV'D = 204215 CF
L0 S 2009YBY-
. . . . . . .
INCREM
TOTAL
fi
SA (5F)
VOL, (CF)
VOL, (CF)
30
70323
0
0
31
73G09
719GG
719GG
32
7G951
75260
14724G
33
80349
78G50
22589G
34
83803
8207G
307971
35
87312
85558
393529
3G
95110
91211
454740
f-5A *-DEPTH REQ MET
F AVE DEPTH = VOL / 5A
= 5 09GG5
REQ'D VOLUME = 20% OF VOL TOTAL AT MIN REQ'D 5A AND DEPTH =
94 4% REQ'D VOLUME EAST FOREBAY= 42G49 I CF
5 G% REQ'D VOLUME WEST FOREBAY= 2530 CF
CHECK FOREBAY VOLUME
EASTERN FOREBAY
INCREM
TOTAL
EL,
5A (5P)
VOL, (CF)
VOL, (CF)
30
5798
0
0
31
G823
G310
G310
32
7915
73G9
13G79
33
9073
8494
22172
34
10298
9G85
31658
35
1590
10944
42802
42802 CF 5 O' DEEP FOREBAY
45170
42802 - = 42G49
VOL PROV'D=
-
42802
42G49 =VOL REQ'D OK
.... ..........
CHECK FOREBAY VOLUME
WESTERN
FOREBAY
INCREM
TOTAL RECEI ri
E.
SA (SF)
VOL. (CF)
VOL- (CF) Mqy n 8 20pg
30
34
0
0
I
31
144
89
89 gy
32
332
238
327
33
537
4G4
791
34
340
7G9
15G0
35
13G0
1150
2710
2710
CF 5 O' DEEP FOREBAY
. . . .. ..
2710
.
—=
. .
2530
. . .. ....... . . . ..
VOL PROV'D=
2710
2530 =VOL REQ'D OK
PROV'D VOLUME _
Q2=
0 2G2901 7
CF5
(FOR 2 DAY DRAWDOWN)
Q5=
0 105 1 G07
CF5
(FOR 5 DAY DPAWDOWN)
J
SELECT A 3" CIRCULAR
ORIFICE, EL 3G
0' (PERM
POOL EL )
ORIFICE 51ZING REQ'D
DPAWDOWN
TIME = 2-5
DAYS
WHERE
Cd= 0 G
A= 0 0451 SF
g= 32 2 FPS/5
Q PROV'D=
0 23G42
h= AVE HEAD =
(TOP OF OUTLET 5TR -PERM POOL EL )/2
Q PROV'D=
Cd'A'(2gh) ^
112
= 1
DPAWDOWN TIME
Q2> 0 23G42 >Q5 OK
TIME = VOLUM = 2 224 DAYS
Q PROVE)
WET DETENTION BA51N DATA 5HE
OCEAN I5LE PALM5 PHASE I
POND # 14
DRAINAGE AREA (Ad) =
2 233 321 5F
IMPERVIOUS AREA (Ai)
BUILDINGS
750 000 SF
ROAD5
279 220 5F
GUARDHOUSE
435 5F
51DEWALK5
0 5F
ALLEYWAYS
121 9G8 5F
TOTAL
1 151 G23 SE
ET RECEI E
7MAY ZOOS
BY�----
(1 25 LOT5@ G 0005F/LOT)
PERCENT IMPERVIOUS (1)
I = AJAcl = 51 5707.
CALCULATE AVERAGE DEPTH (Davg)
5EE AVERAGE DEPTH CALCULATION SPREADSHEET POP POND # 14
CALCULATE REQUIRED SURFACE AREA AT PERMANENT POOL
POND# 14 SHALL BE 13' DEEP HAVE AN AVERAGE DEPTH Of 7 00' AND BE DESIGNED TO REMOVE 90% T55
INTERPOLATION Of TABLE 10 4 IN NCDENR 5TORMWATER BMP MANUAL
% IMP
AVERAGE DEPTH (FT)
G5
700
1 75
50
2 30
190
1 50
52
242
200
1 58
GO
200
240
1 90
SA/DA= 2 00%
5A,, = 44 GGG 5F = 1 03 AC
SURFACE AREA PROVIDED AT PERMANENT POOL (ELEV G 0) = 50 49 1 5F
SA PROV D= 50 49 1 > 44 GGG =5A REQ'D OK
P \509\809 02\Calc5\POND545PREAD5HEET5\POND#14 A5
POND 14
DATA 5HEET
PAGE I OF 4
WET DETENTION BA51N DATA SHEET
OCEAN I5LE PALMS -PHASE I
POND #2 1
DRAINAGE AREA (Ad) =
1 ,093,G85 51'
IMPERVIOUS AREA (A)
BUILDINGS
2G 1,000 SF
ROAD5
134,557 5F
AMENITY CENTER
93,G54 5F
OFF -SITE
0 5F
FUTURE DEVELOPMMENT
0 SF
SIDEWALKS
22 548 5F
ALLEY WAY5
20,413 5F
RESERVE
29,500 5F
TOTAL
5GI,G72 51'
PERCENT IMPERVIOUS (1)
I = At/Acl = 51 3G%
CALCULATE AVERAGE DEPTH (Davg)
MAY 8 11`
C
(43 5 LOT5@ G 0005F/LOT)
SEE AVERAGE DEPTH CALCULATION SPREADSHEET FOR POND #2 1 (,,(, 4)
CALCULATE REQUIRED SURFACE AREA AT PERMANENT POOL
POND#21 SHALL BE 1 I' DEEP, HAVE AN AVERAGE DEPTH OF G 50' AND BE DESIGNED TO REMOVE 90%T55
INTERPOLATION OF TABLE 10-4 IN NCDENR 5TORMWATER BMP MANUAL
% IMP
AVERAGE DEPTH (FT)
GO
G50
70
50
2 70
230
1 90
52
254
242
200
GO
340
2 90
240
5A/DA= 2 42%
5AREG = 2G 4G7 5F =
0 G I AC
SURFACE AREA PROVIDED AT PERMANENT POOL (ELEV G 0) = G2 543 5F
5A PROV'D= G2,543 > 2G 4G7 =5A REQ'D OK
P\809\809-02\Calc5\PONDS\5PREAD5tiEET5TOND#2 1 xl5
POND #21
DATA SHEET
PAGE I OF 4
MINIMUM REQUIRED VOLUME (SIMPLE METHOD BY TOM 5CHUELER)
Rv=O 05+0 009 (1)
Rv= 0 5 12203
VOLUME= " Rv'Ad = 1 07 AC -FT
= 4G G82 FT-3
VOLUME PROVIDED AT TEMPORARY POOL
INCREM
TOTAL
EL.
5A (5F)
VOL, (CF)
VOL, (CF)
G
G2 543
0
0
G 5
47,287
27 458
27,458
7
7I ,74 I
29,757
57,215
8
77 373
74,557
131 772
9
83 072
80 223
21 1 994
10
88913
85 993
297 987
5ET TEMP POOL ELEVATION
REQ'D EL = G 82
PROV'D EL= 800
VOL PROV'D = 13 1,772 CF
VOL PROV'D= 131,772 > 4G G82 =VOL REQ'D
L
FOREBAY SIZING
PERMANENT POOL VOLUME
INCREM
TOTAL
EL_
5A (5F)
VOL (CF)
VOL (CF)
-5
9,550
0
0
-4
12 G37
1 1,094
1 1 094
-3
1 G 047
14,342
25,43G
-2
1 9,80G
17927
43 3G2
- 1
24 G75
22 241
G5 G03
0
29,1GO
2G,918
92,520
1
33,782
31 471
123 991
2
38 53G
3G 159
1 GO, 1 50
3
43,781
41,159
201,309
4
48,43G
4G 109
247 41 7
5
53 584
51 010
295,427
5 5
5G,233
27,454
325,581
G
G2,543
29 G94
355 575
P =9M9-02\CaIc5TOND5\5PREAD5hEET5\POND#21 Ar
DECEIVE
MAY 0 8 2009
BY
OK
5URFACEAREA
< REQ MET
POND #21
DATA SHEET
PAGE 2 OF 4
REQ'D FOREBAY VOLUME = 20% TOTAL =
CHECK FOREBAY VOLUME
18,504 CF
MAY Zfl09
BY
INCREM
TOTAL
f.L
5A (5F)
VOL (CF)
VOL, (CF)
-5
1,501
0
0
-4
2,201
1 851
I ,85 1
-3
3 151
2 G7G
4,527
-2
4 380
3,7GG
8 293
- I
G G4G
5,513
13 8OG
0
8,457
7 552
21,357
1
10333
9 395
30,752
2
12 2G9
1 1,301
42,053
3
14 2G5
13,2G7
55 320
5
18,435
32,700
88 020
5 5
19,535
9,493
97,513
G
20,G31
10 042
107,554
PROV'D VOLUME =
107 554
CF (I I' DEEP FOREBAY)
VOL PROV'D=
107,554
>
18,504 =VOL REQ'D
ORIFICE 51ZING REQ'D DRAWDOWN TIME = 2-5 DAY5
NOTE ORIFICE 51ZED TO DRAWDOWN THE TEMPORARY POOL IN 2-5 DAY5
02= 0 27015 CF5 (FOR 2 DAY DRAWDOWN)
Q5= 0 108OG CF5 (FOR 5 DAY DRAWDOWN)
ORIFICE EL = GOO (PERM POOL EL)
TEMP POOL EL = 8 00 (OUTLET EL)
ORIFICE DIAMETER = 300 IN
OK FOREBAY AND MAIN
POOL ARE SAME DEPTH
Q PROV'D= Cd A*(2gh) ^ 112 WHERE Cd= 0 G
A= 0 040 5F
g= 32 2 FP5/5
h= (TEMP POOL -NORMAL POOL)/3
0 GG7
Q PROV'D= 0 19295
Q2> 0 19295 >Q5 OK
DRAWDOWN TIME
TIME = VOLUME = 280 DAYS
Q PROV'D
P\809M9-02\CaIc5\PONDS\5PPfAD5HEET5\POND#21 A5
POND #21
DATA SHEET
PAGE 3 OF 4
AVERAGE DEPTH CALCULATION
DESIGN CALCULATIONS POP
OCEAN I5LE PALMS - PHASE I - POND 21
DEPTH
TT)
SURFACE AREA
AT DEPTH
(5F)
INC VOL
AT DEPTH
(CF)
TOTAL VOL
AT DEPTH
(CF)
Option #I
(PT
00
62 543
0
0
000
0 5
56 233
29 694
29 694
047
1 0
53 584
27 454
57 148
091
2 0
48 436
51 010
108 158
1 73
30
43 751
46 109
154 267
247
40
38 536
41 159
195425
3 12
50
33 782
36 159
231 584
370
6 0
29 1 60
31 471
263 055
4 21
70
24 675
26 915
289 973
4 64
80
19806
22241
3)2213
499
9 0
16047
17927
330 140
5 28
1 0 0
12 637
14342
344 482
5 5 1
1 1 0
9 550
1 1 094
355 575
5 69
120
130
20
160
P \809\809 02\CaIC5\POND5\5PREAD5HEET5\POND#21 A5
DATE 5/7/09
PROJECT NO 809-02
DESIGNED 13Y T PURVIS
Option #2
A,,t ,h,p =
56 233
5P
A,,,,,, ,,,o, =
62 543
SF
Ate, ,,,,,d =
9 550
5F
Depth =
105
FT
D,,, =1
6 62
FT
LEE 6 5 FT
POND #21
AVERAGE DEPTH
PAGE I OF I
MINIMUM REQUIRED VOLUME (SIMPLE METHOD BY TOM SCHUELER)
Rv=O 05+0 005 (U
Rv= 0 5 14083
VOLUME= I" Kv Ad = 2 20 AC -FT
95 G77 FT-3
VOLUME PROVIDED AT TEMPORARY POOL
INCREM
TOTAL
EL
SA (5F)
VOL (CF)
VOL (CF)
8
50431
0
O
9
55351
54 42 1
54 42 1
10
G2 08G
GO 2 1 9
1) 4 G40
I I
G5 500
G3 088
178 G28
12
G9 7G2
G7 82G
24G 454
5ET TEMP POOL ELEVATION
REQD EL = 9 G9
PROV'D EL= 9 90
VOL PROV O = 108 G 18 CF
VOL PROV'D= 108 G 18 >
FOREBAY 51ZING
PERMANENT POOL VOLUME
95 G77 =VOL REQ'D OK
INCREM
TOTAL
EL
5A (5F)
VOL (CF)
VOL, (CF)
-5
9 97G
0
0
-4
1 2 201
1 1 059
1 1 085
-3
14 528
13 3G5
24 453
-2
1 G 990
15759
40212
-1
19 G3G
15313
58 525
0
22 394
21 015
79 540
1
25 253
23 544
03 384
2
28 345
2G 815
130 203
3
3 1 4G8
29 907
1 GO 109
4
34 GG3
33 OGG
193 175
5
37 927
3G 295
229 470
G
41 2G 1
39 594
2G9 OG4
7
44 GG4
42 9G3
3 1 2 02G
8
50 491
47 575
359 G04
P \809\809 02\Calc5\POND545PREAD5HEET5\POND# 14 x15
SURFACE AREA
< 4 DEPTH REQ MET
RECEIVED
MAY 0 S 2009
BY
POND 14
DATA 5HEET
PAGE 2 OF 4
REQ'D POPE DAY VOLUME = 20% TOTAL = G2 405 CF
CHECK FOREBAY VOLUME
INCREM
TOTAL
FL.
SA (5F)
VOL (CF)
VOL (CF)
5
239
O
0
-4
527
383
383
-3
927
727
I110
-2
1547
1 237
2 347
-
2 235
1 521
4 2G8
0
3 IGI
2 728
G 99G
4 23G
3 G99
10 G95
2
5 392
4514
15509
3
GG25
G011
21 519
4
7 94G
7 255
28 507
5
9 342
8 G44
37 45 I
G
10 518
10 080
47 531
7
12373
1 1 59G
59 1 2G
PROV'D VOLUME =
59 1 2G
CF (I I' DEEP FOREBAY)
VOL PROV'D=
59 1 2G
—
G2 405 =VOL REQ'D
ORIFICE 51ZING REQ'D DRAWDOWN TIME = 2-5 DAYS
OK
NOTE ORIFICE SIZED TO DRAWDOWN THE TEMPORARY POOL IN 2-5 DAYS
Q2= 0 553G9 CPS (FOR 2 DAY DRAWDOWN)
Q5= 0 22148 CPS (FOR 5 DAY DRAWDOWN)
ORIFICE EL = 800 (PERM POOL EL)
TEMP POOL EL = 990 (OUTLET EL)
ORIFICE DIAMETER = 400 IN
Q PROVD= CXA (2gh)^ 1/2 WHERE Cd= 0 G
A= O 087 SF
g= 32 2 FP5/S
h= (TEMP POOL -NORMAL POOL)/3
= O G33
Q PROV'D= 0 33439
02> 033439 >05 OK
DRAWDOWN TIME
TIME = VOUIMF = 331 DAYS
Q PROV'D
7CEIVED
M AY 0 S 2009
BY �--
POND 14
DATA 5HEET
P\509Z09-02\Ca1c5\POND515PREAD5HEET5SPONDk 14 A5 PAGE 3 OF 4
AVERAGE DEPTH CALCULATION
DE51GN CALCULATIONS FOR
OCEAN 15LE PALMS - PHASE I - POND 14
DEPTH
(FT)
SURFACE AREA
AT DEPTH
(5F)
INC VOL
AT DEPTH
(CF)
TOTAL VOL
AT DEPTH
(CF)
Option#I
(FT)
00
50 491
O
O
0 DO
1 0
44 GG4
47 575
47 578
0 94
2 0
41 291
42 9G3
90 540
1 79
3 0
37 927
39 594
130 134
2 58
40
34 GG3
3G 295
1 GG 429
3 30
5 0
31 4G8
33 OGG
199 495
395
G 0
28 345
29 907
229 40)
4 54
70
25 293
29819
25C 220
507
8 0
22 394
23 844
280 OG4
5 55
9 0
19 G3G
2) 015
301 079
5 9G
100
1 G 990
18 313
319 392
G 33
11 0
14 528
15 759
335 151
G G4
1 2 0
12 201
13 3G5
345 51 5
G 90
130
9 97G
11 059
359 G04
7 12
140
150
IGO
170
P\509\809-02\Ca1c5\PONDS\5PREADSHEET5POND#14 xl5
AVG DEPTH = 7 0
REC
MAY 0 8 2009
BY
DATE 5/7/09
PROJECT NO 505-02
DESIGNED BY T PURV15
POND 14
AVERAGE DEPTH
PAGE 4 OF 4
��� CAPE FEAR
Engineering, Inc.
151 Poole RoeC Score IW
Be1v111e NC 25 51
TEL (810) WB 10
FAX (910) 383-1 5
www capefearengmeenng com
To
NCDWQ Surface Water Protection
Wilmington Regional Office
Attn
Mary Jean Naugle
❑ As Requested ® For Your Files
❑ Sent via Mad ❑ Sent via Courier
Nip WAlh,
Transmittal
Date May 5, 2009
File 809-02 "36"
Subject Ocean Isle Palms SW8 060338
Deed Restrictions
❑ For Distribution ❑ For your Review / Action / Approval
Quantity
Drawing No
Description
1
copy
Stormwater Management Permit SW8 060338
1
copy
Recorded Protective Covenants for Ocean Isle Palms (may be amended to
reflect BUA of 6000 square feet per lot)
tw k- c v
mt�i� i�mc�il
REMARKS
0
CC File
File 809-02"36"
Cape Fear
Engineering, Inc
Signed /�l�c �f'� ZtzL
Received By
Date
-1O
G`
Engineer's Report
For
Analysis of Pond #12 & #21 under SHWT Conditions
Request for Additional Information
Stormwater Permit No. SW8 060338
Ocean Isle Palms Phase I
Brunswick County
Subject:
Ocean Isle Palms
Phase 1
Brunswick County, North Carolina
Prepared for
Ocean Isle Palms, LLC
131 Ocean Blvd West
Holden Beach, NC 28462
(910)754-2224
Date March 2009
Prepared by
Cape Fear Engineering, Inc.
151 Poole Road, Suite 100
Belville, NC 28451
(910)383-1044
Rmcm)EVRI)
MAR 0 9 2009
BY:
P \809\809-02\Ca1cs\Storm\SHWT ISSUE\Engmeer's Report REV 3-4-09 doc I
EnEmeer's Report: Phase 1 — Pond #12 & #21
NCDENR REQUEST
The Wilmington Regional Office received an incomplete Plan Revision regarding the State
Stormwater Management Permit for Ocean Isle Palms on April 30, 2008 The cover letter
indicated that the proposed plan revision is to remove the previously permitted clay liners for the
ponds On May 8, 2008, the Division sent an email to your consultant indicating that the pond's
temporary storage volume be verified due to the permanent pool elevation being located so far
below the seasonal high water table On June 5, 2008, a single plan sheet was submitted for
Pond #12, with a revised SHWT As of this date, the plan revision to remove the clay liners is
still not complete and cannot be accepted for review until the following information is
submitted
A Please advise as to the status of construction on these ponds Have the ponds already
been constructed? Were they constructed with or without the approved clay liners? If
they have been constructed without the permitted clay liner, you will most likely be
required to monitor the ponds in lieu of enforcement action
B Please demonstrate that sufficient storage has been provided for the required design
storm Locating the permanent pool elevation so far into the water table will most likely
result in a higher pool elevation, meaning that necessary storage space for the design
storm is being taken up by the permanent pool Groundwater modeling to quantify the
expected volume of incoming groundwater based on soil type and transmissibility is an
option
C Please demonstrate that the outlet ditched that the pond discharges into are free flowing
under expected high water table conditions With the permanent pool elevation so far
down in the water table, it is imperative that the outlets function effectively under high
water conditions in order for the pond to drawdown to the design permanent pool
elevation within the required 2-5 days and to have the required storage volume available
for the next storm
P \809\809 02\Ca1cs\Storm\SH WT ISSUE\Engmeer s Report REV 3-4-09 doc
RESPONSE PREFACE
This evaluation of the subject water quality ponds (Pond #12 & #21) is predicated upon
NCDENR's review of the subject development's stormwater submittal from June 8, 2008
The fundamental premise for this request for additional information surrounds NCDENR's
position that the post -development seasonal high water table (SHWT) will equal that of pre -
development conditions and will affect the subject water quality pond's function with respect to
the design storm
With NCDENR's concern focusing on groundwater migration from SHWT influence as
described, this report treats all groundwater flow within the hydraulic radius of the pond as
entering the pond This treatment is necessary to quantify the effects of SHWT influences on the
pond and the downstream conveyance
As such, the demonstration of downstream capacity treats the downstream conveyance as
initially dry However, whether groundwater under SHWT influence daylights within the
downstream conveyance or within the pond, the flowrate herein quantified for groundwater is the
same
Therefore, our calculations demonstrate that neither the design storm storage nor discharge is
compromised by groundwater, regardless
The following response to NCDENR's letter is provided
RESPONSE
A Status of Construction
Pond #12
1 Pond # 12 is an existing pond that has been in place for approximately 2 years or
more Pond #12 was later modified and designed for stormwater treatment The
developer is in the process of converting this existing pond into a stormwater
pond A clay liner has not been installed to date and this submittal will
demonstrate that one is not needed
Pond #21
2 Pond #21 has not been constructed
B Quantify Groundwater Flow
For purposes of quantifying GW flow, Darcy's law was used
Q = kA dh where,
dl
k = hydraulic conductivity
A = cross sectional area perpendicular to flow
P \809\809 02\Calcs\Storm\SHWT ISSUE\Engmeer s Report REV 34-09 doe
dh/dl = hydraulic gradient
Determine Soil Types and Hydraulic Conductivity (k)
In order to quantify the amount of groundwater flowing into the pond under
SHWT conditions, the hydraulic conductivity of the soils that contribute flow to
the pond must be determined Since there are various soil types in the vicinity of
the pond, and the hydraulic conductivity for each soil changes as a function of
depth below the ground surface, the following steps were taken to calculate a
weighted average hydraulic conductivity (See Figures 1&2 for an illustration of
the soil types located in the vicinity of the proposed ponds )
i The types of soils present in the vicinity of the pond were determined from
Brunswick County GIS
ii Physical soil data for each of the soils located in the vicinity of the pond was
obtained from the "Soil Survey of Brunswick County" It was assumed that
the permeability of the soil would closely resemble the hydraulic
conductivity of the soil (see "Appendix B")
ni For each soil in the vicinity of the ponds, the weighted hydraulic
conductivity of the soil was determined (see Table-1 in "Appendix C")
IV A weighted average hydraulic conductivity was determined for the ponds
based on the approximate linear footage of the normal pool that was in each
soil type (see Table-2 in "Appendix C")
*** Please see "Appendix B" for excerpted soil narratives for subject soils
Estimate Hydraulic Radius (ill)
In order to quantify the amount of groundwater flowing into the pond under
SHWT conditions, the hydraulic radius must be estimated The hydraulic radius
defines the zone of groundwater influence and can be described as the distance
away from the pond where groundwater flow will be in the direction of the pond
(See Sheet F-I & F-2 for an illustration of the hydraulic length)
Large hydraulic radii indicate shallow hydraulic gradients and little driving head,
small hydraulic radii indicate steep hydraulic gradients and greater dnving head
For these particular ponds, the following criteria were used to estimate the
employed hydraulic radius The criteria and their relevance to this pond are
described in detail below
Existing Topography and the assertion that subsurface hydrology will
closely resemble surface hydrologyfor this riverine system
Pond #12
There is a ridge located to the north of the proposed Pond #12 location
This ndge creates a natural drainage area divide Areas south of this
ndge will contribute southward flows to the proposed pond and
ultimately the pond's reach Areas north of this ridge will contribute
northward flow to the Ex Stump Pond north of proposed St Lucia Dr
and ultimately to a separate reach (See Sheet F-1)
P \80%809 0Ma1cs\Storm\SHWT ISSMEngmeer's Report REV 3-4 09 doc
Pond #21
The west drainage divide occurs at Curacao Drive, while the east
divide is at Adelaide Avenue, the northern divide follows Adelaide
Avenue north till it reaches Martinique Street and terminates at the
intersection Also, there is an offshoot that follows North Bimini Road
from the intersection with Adelaide Avenue west where it reaches the
roundabout and terminates Areas west of this drainage area will
contribute flow into Pond 914, areas east of Adelaide Ave are
considered "future development" and will be treated as the subdivision
design progresses (See Sheet P-2)
For these reasons, the hydraulic radius was chosen as 350 feet for Pond #12
(shown on Sheet F-1 and reflected in the calculations), and 35 feet for Pond #21
(shown on Sheet F-2 and reflected in the calculations) By keeping these radii
smaller than the confining site characteristics described in 1 above, the hydraulic
gradient is made steeper, resulting in a more conservative determination in the
following flowrate quantification
Determine Groundwater Flowrate (Q)
As Darcy's Law was used to quantify the amount of groundwater flowing into the
ponds during SHWT conditions, groundwater flow into each pond was calculated
at incremental intervals from the estimated SHWT elevation to the bottom of the
pond
Pond #12
The groundwater flow into Pond #12 was calculated at incremental intervals
from the SHWT elevation of 38 42' to the bottom of the pond at elevation 30 ft
The total groundwater flow into the pond was quantified as the sum of
incremental flowrates from each said interval This determination produced a
groundwater flow into Pond 412 as 0 213 cfs (please refer to "Appendix D" for
calculations)
Pond #21
The groundwater flow into Pond #21 was calculated at incremental intervals
from the SHWT elevation of 9 08' to the bottom of the pond at elevation -7 ft
The total groundwater flow into the pond was quantified as the sum of
incremental flowrates from each said interval This determination produced a
groundwater flow into Pond #21 as 0 17 cfs (please refer to "Appendix D" for
calculations)
The following assumptions were employed in determining the groundwater
flowrate into the ponds
Assumptions and References
P \809\809 02\Calcs\Srorrn\SHWT ISSUE\Fngmeer s Report REV 34-09 doe
• As dictated by NCDENR's request for additional information, it was assumed
that post -development SHWT elevations will approximate pre -development
SHWT elevations
• The Groundwater flowrate was calculated based on a steady state analysis for
the most extreme condition (Groundwater Elevation = estimated SHWT
elevation)
• Hydraulic Conductivity from Brunswick County Soils Series as discussed
above
• Hydraulic Length was assumed based on the factors discussed above
• Soils mapped immediately at the proposed normal pool location govern the
hydraulic conductivity
• For groundwater flow calculations the contributing area was assumed to be
the two-dimensional planar area between contour surface areas
(Also see Table-3 and Sample Calculations-1 in "Appendix D")
C Free Flowing Discharge for Outlets
Pond #12 Downstream Conveyance Analysis
Please refer to the downstream conveyance detail on sheet F-1 This detail shows Pond
# 12 discharging into the Ex Stump Pond, and the Ex Stump Pond discharging offsite to
another Ex Pond Data and discharge quantification terminates at the outlet from the Ex
Stump Pond where it enters the offsite Ex Pond Also, please refer to "Appendix E" for
the routing data for these two ponds From Sheet F-1, please note that the discharge
elevation of Pond #12 is approximately 1-foot above the receiving Ex Stump Pond (an
unnamed tributary to the Class C, SW waterbody Jinny's Branch)
Additionally, FEMA FIRM panel 2066 dated June 2, 2006 shows that the limit of the
100-year flood zone along this creek terminates approximately 1,480-feet downstream of
the point where Pond 412's downstream conveyance reaches surface water (See attached
FIRM Panel)
With the 100-year flood elevation approximating 37 35 It msl, the point of reach
approximating 29 0 ft msl, and the pond outlet being at 36 0 ft msl, it is immediately
evident that the receiving conveyances should graciously accommodate the drawdown of
the NCDENR design storm
Additionally, as shown in the routing calculations for Ex Stump Pond, the maximum
water surface elevation resulting from the 1-year 24-hour storm is 35 48 This leaves
approximately 0 52 feet available for discharge from Pond #12 for the 1-year 24-hour
storm Since the volume from the 1-year 24-hour storm exceeds the NCDENR design
storm, there is no reasonable concern that Pond #12 will back up under SHWT
conditions
2 Pond #21 Downstream Conveyance Analysis
From Sheet F-2, please note that the discharge elevation of Pond 421 is approximately 1-
foot above the receiving Jinny's Branch (Class C, SW waterbody)
P \809\809-02\CaIcs\Stonn\SHw r ISSUE\Engmeer s Report RFV 34 09 doe 6
Please refer to the downstream conveyance detail on sheet F-2 This detail shows Pond
#21 discharging into Ex Jinny's Branch Data and discharge quantification terminates at
the outlet from Pond #21 where it enters the Jinny's Branch Also, please refer to
"Appendix E" for the routing data for Pond #21 and an analysis of Jinny's Branch at the
reception point of Pond #21 (study point shown on Sheet F-2) Routing calculations (in
"Appendix E") show a 1-year 24-hour discharge rate of 4 20 cfs Based on an analysis of
the data (below), groundwater will not effect the operation or compromise Pond #21's
ability to function as a stormwater pond
Pond #21 - Define Jinny's Branch Characteristics at the Pond Outlet
Pond #21 discharges directly into Jiriny's Branch The point of interest (study
point) for this pond is where Pond #21's outfall meets Jinny's Branch (please
see Sheet F-2 for location) At the study point, the top of bank for Jinny's
Branch is at an elevation of 8' msl The bottom of the ditch is at elevation 2'
msl To be conservative in our calculations, it was assumed that the water
surface elevation in Jenny's Branch was equal to the SHWT in Jinny's Branch
at the study point (please see the cross-section detail on Sheet F-2)
a) Longitudinal Slope
The SHWT elevation for Jinny's Branch at the outlet from Pond
#21 is 5 0' msl Surveyed information terminates roughly 1,340'
downstream of the outlet for Pond 421 at elevation 4 14' msl
According to surveyed information, the approximate longitudinal
slope of Jinny's Branch is 0 064%
b) Width
The width of Jinny's Branch at the study point is 66' at the top of
bank and 52' at the SHWT level
c) Side Slope
Based on surveyed information the average side slope ratio was
calculated as approximately 2 1
Calculate Depth of Flow in Jinny's Branch Due to 1-year 24-hour Storm
Referencing the attached Hydraflow data in "Appendix E" for the upstream
catchments, the combined discharge for the 1-year 24-hour rainfall event is equal
to 4 20 cfs Jenny's Branch was modeled and a channel report was created to
show that when flowing at 4 20 cfs the water surface elevation will be 0 20 ft
above the SHWT, resulting in a water surface elevation of 5 20 feet with
approximately 2 80 feet of freeboard
*See "Appendix F"
(Calculations were performed using Hydraflow Express Extensions)
Calculate the Flowrate in Jinny's Branch when Flowing Full
According to Hydraflow Extensions modeling software, Jenny's Branch, when
flowing at full capacity, can carry a flowrate of approximately 405 42 cfs (see
"Appendix F" for results) Furthermore, the discharge for the 100 year rainfall
event from Pond #21 is 106 82 cfs (see "Appendix E") This modeling shows the
P \809\809 02\Ca1cs\Stortn\SHWT ISSUF\Engtneer's Report REV 3-4-09 doe
ditch capacity exceeds the current project requirements to handle the discharge
even when under SHWT conditions
*See "Appendix F"
(Calculations were performed using Hydraflow Express Extensions)
For additional discussion, please consider the following
As the prescribed wet -detention design for the NCDENR water quality ponds (Pond #12
& #21) dictates that the 1-inch storm draws down in 2-5 days, the design drawdown with
respect to the receiving body can be hydraulically described in the following manner
The New Hanover County Stormwater Design Manual indicates that the 1-mch rainfall
event can occur from storms with the following frequencies and durations 2 year /15
minute, 5 year/10 minute, or 10 year/ 10 minute (See Appendix A) As no possible 1-
inch storm approximates the 100-year event, there should be no realistic compromise to
the downstream conveyance under NCDENR's design storm with or without
groundwater influence
Therefore, surface water should not compromise the functioning of the Pond #12 and
Pond 421 orifice
D Evaluate Orifice
Pond 412
The orifice was evaluated to determine if its size can effectively deal with incoming
groundwater as quantified while maintaining the design permanent pool and NCDENR
design storm drawdown requirements This calculation is detailed on pages 4 and 5 of the
Pond#12 calculation spreadsheet (See Pond #12 Calculations in Appendix E) The
orifice draws down in 14 48 days while operating under SHWT conditions Changing the
orifice size to 4 0" reduces the drawdown to 3 97 days Since the SHWT considers the
extreme case for water quality we are proposing not to change the orifice size
Pond #21
The orifice was evaluated to determine if its size can effectively deal with incoming
groundwater as quantified while maintaining the design permanent pool and NCDENR
design storm drawdown requirements This calculation is detailed on pages 4 and 5 of the
Pond#21 calculation spreadsheet (See Pond #21 Calculations in Appendix E) The
orifice draws down in 8 41 days while operating under SHWT conditions Changing the
orifice size to 3 5" reduces the drawdown time to 3 28 days (see calcs in Appendix E)
Since the SHWT considers the extreme case for water quality we are proposing not to
change the orifice size
P \809\809-02\Calcs\Stonn\SHWT ISSUE\Engmeers Report REV 34-09 doe
Appendix A
New Hanover County Design Storm Information
P \809\809-02\Calcs\Storm\SHWT ISSUE\Engmeer's Report REV 34 09 doc 9
NEW HANOVER COUNTY STORM WATER DEMGNMANUAL
SmYON40 - RUNOFFDETERmwATTONPROCEDURES
TABLE 40-3
NEW HANOVER COUNTY
DEPTH — DURATION — FREQUENCY TABLE
TABLE 40-3A
Duration
Return Period
2-yr
5-yr
10-yr
25-yr
50-yr
100-yr
(fie)
(m)
(m)
(m)
(m)
(m)
(m)
5 min
049
055
060
068
074
080
10 min
088
0 99
1 07
120
131
141
15 min
1 15
129
140
157
170
184
30 min
162
192
214
247
273
299
60 min
210
258
292
341
380
418
2 hr
250
330
360
420
470
520
3 hr
280
3 50
405
4 70
520
580
6hr
330
420
482
571
640
700
12 hr
390
500
580
690
770 ---8
60
24 hr
450
580
700
805
900
10001
TABLE 40-3B
Duration
Return Period
2-yr
5-yr
10-yr
25-yr
50-yr
100-yr
(tune)
(m/hr)
(m/hr)
(m/hr)
(m/hr)
(m/hr)
(mft)
5 min
588
663
723
815
887
960
10 min
528
591
643
722
785
848
15 nun
460
5 15
559
627
682
736
30 nun
323
384
428
494
546
597
60 nun
210
258
292
341
380
418
2 hr
125
165
180
210
235
260
3 hr
093
117
135
157
173
193
6 hr
055
070
080
095
107
117
12hr
033
042
048
058
064
072
24hr
019
024
029
034
038
042
Source Latest Versions of NWS TR-40 and NWS Hydro-35
ADOPTED SEPTEMEER 5, 2000 PAGE 40-5
Appendix B
Excerpted Sod Narratives
Physical and Chemical Properties of the Soils
P \809\809 02\Calcs\Storm\SH WT ISSUETngmeer s Report REV 3-4 09 doe 10
Page 1 of I
F:quie d
http:/1gis.brunsco.nctloutput/BrttnsNiicl Noc_arc-itns-ser%er4I3612885947 jpg 1 12. ,2008
E11-4 to 9 inches, pale brown (10YR 6/3) fine sandy
loam, weak medium granular structure, very friable,
common fine roots, very strongly acid, clear wavy
boundary
E2-9 to 13 inches, brownish yellow (10YR 6/6) fine
sandy loam, weak fine subangular blocky structure,
very friable, very strongly acid, clear wavy boundary
Btl-13 to 16 inches yellowish brown (10YR 5/4) sandy
clay loam, weak fine subangular blocky structure,
friable, very strongly acid gradual wavy boundary
Bt2-16 to 30 inches light yellowish brown (10YR 6/4)
sandy clay loam few medium distinct brownish
yellow (10YR 6/8) mottles and common medium
distinct light brownish gray (10YR 612) mottles,
weak fine subangular blocky structure friable very
strongly acid, gradual wavy boundary
BCg-30 to 38 inches, light brownish gray (10YR 6/2)
sandy clay loam that has pockets of sandy loam
few medium distinct strong brown (7 SYR 5/8)
mottles, weak fine subangular blocky structure,
friable, very strongly acid, clear wavy boundary
2Cgl-38 to 46 inches, mottled gray (10YR 6/1), light
yellowish brown (10YR 6/4), and brownish yellow
(10YR 6/8) loamy sand that has strata of sand
single grained, loose, very strongly acid gradual
l wavy boundary
2Cg2-46 to 70 inches, light gray (I OYR 7/2) sand, few
medium distinct light yellowish brown (10YR 6/4)
mottles, single grained, loose, very strongly acid
The sandy A and E horizons and loamy St horizons
have a combined thickness of less than 40 inches over
sandy sediment The sods are very strongly acid or
strongly acid throughout, unless the surface layer has
been limed
The Ap or A horizon has hue of 10YR, value of 3 or 4
and chroma of 1 or 2
The E horizon has hue of 1 OYR or 2 SY, value of 5 or
7, and chroma of 3 to 6 Texture is loamy sand sandy
loam, or fine sandy loam
The Bt horizon has hue of 1 OYR or 2 5Y, value of 5 to
7 and chroma of 4 to 8 In some pedons the Bt horizon
has few to common mottles in chroma of 2 or less
Texture is sandy clay loam or sandy loam The BCg
horizon has hue of 10YR value of 5 to 7, and chroma of
1 or 2 Texture is sandy clay loam or sandy loam Some
pedons of the BCg horizon have thin strata of these
textures
The 2Cg horizon has hue of 10YR, value of 5 to 8,
and chroma of 1 or 2 Texture is sand or loamy sand
�Kureb_Senes
The Kureb series consists of excessively drained sods
I uplands The sods formed in coarse textured
,ediment Slopes range from 1 to 8 percent
Typical pedon of Kureb fine sand 1 to 8 percent
slopes, 1 7 miles east of Gause Landing, 1 3 miles east
Soil Survey
of the intersection of N C Highway 904 and State Road
1172 150 feet south of the intersection of N C Highway
904 and State Road 1183
A-0 to 4 inches, gray (1OYR 5/1) fine sand, single
grained, loose, common uncoated sand grains,
many fine and few coarse roots, slightly acid clear
wavy boundary
E-4 to 20 inches, light gray (10YR 7/1) fine sand,
single grained, loose, common fine and few coarse
roots, neutral, clear wavy boundary
C/Bh1-20 to 40 inches, brownish yellow (10YR 6/6)
fine sand single grained, loose, 10 percent dark
brown (7 SYR 4/4) and reddish brown (5YR 5/3) Bh
bodies, few medium and coarse roots, neutral,
gradual wavy boundary
C/Bh2-40 to 53 inches, brownish yellow (10YR 6/8)
fine sand, common medium distinct dark reddish
brown (5YR 3/2) vertical bands and mottles and thin
streaks of yellowish brown (10YR 5/6), single
grained loose, few coarse roots, few coarse weakly
cemented reddish brown (5YR 4/4) concretions, few
small pockets of uncoated sand grams, neutral,
gradual wavy boundary
C1-53 to 70 inches, light yellowish brown (1 OYR 6/4)
fine sand, common medium faint brown (10YR 5/3)
mottles and common medium distinct light gray
(10YR 7/1) mottles, single grained, loose, neutral
gradual wavy boundary
C2-70 to 80 inches, light yellowish brown (I OYR 6/4)
fine sand, single grained loose, neutral
The sandy horizons extend to 80 inches or more The
sod ranges from strongly acid to neutral throughout,
unless the surface layer has been limed
The A horizon has hue of 10YR, value of 3 to 6 and
chroma of 1 or 2
The E horizon has hue of 1 OYR, value of 7 or 8 and
chroma of 1 or 2 Texture is sand or fine sand
The C part of the C/Bh horizon has hue of 10YR
value of 5 to 8 and chroma of 4 to 8 The Bh part of the
C/Bh horizon has hue of SYR to 1 OYR, value of 3 to 6
and chroma of 2 to 6 The C/Sh horizon is sand or fine
sand
The C horizon has hue of IOYR value of 6 to 8, and
chroma of 1 to 8 Mottles are in shades of these colors
Texture is sand, fine sand or loamy sand
Witte Series
The Lafitte series consists of very poorly drained soils
on low flood plains adjoining salt water They are below
5 feet in elevation and are flooded daily with saline
water The soils formed from herbaceous plant residue
and small amounts of mineral soil sediment Slopes are
less than 1 percent
Brunswick County North Carolina
Typical pedon of Lafitte muck, 4 0 miles west of
Southport, 0 8 mile southwest of Long Beach Bridge and
250 feet south of the Intracoastal Waterway in marsh
Oat-0 to 12 inches, dark brown (7 5YR 3/2) muck
pressed and rubbed about 35 percent fiber, about
15 percent rubbed massive, many fine and medium
live roots, few coarse stems, about 50 percent
mineral content, moderately alkaline, clear smooth
boundary
Oa2-12 to 30 inches, black (10YR 2/1) muck rubbed
and pressed, about 30 percent fiber, about 5
percent rubbed, massive, few fine and medium
roots, about 60 percent mineral content moderately
alkaline, gradual wavy boundary
Oa3-30 to 40 inches, very dark brown (10YR 2/2)
muck pressed and rubbed, about 35 percent fiber
about 10 percent rubbed, massive common medium
roots few coarse stems, about 50 percent mineral
content, moderately alkaline, gradual wavy
boundary
Oa4-40 to 55 inches very dark gray (10YR 3/1) muck
and thin dark gray (5Y 4/1) mineral strata, about 5
percent fiber, about 1 percent rubbed fiber massive,
about 70 percent mineral moderately alkaline,
gradual wavy boundary
2Cg-55 to 72 inches gray (5Y 5/1) silty clay massive
flows easily through fingers when squeezed,
moderately alkaline
The decomposed organic layers range from 51 inches
to more than 80 inches thick The soil ranges from
neutral to moderately alkaline
The surface and subsurface organic layers have hue
of 7 5YR or 10YR, value of 2 or 3, and chroma of 1 or 2
The underlying mineral soil has hue of 5Y or SGY, or it
is neutral, and has value of 3 to 5 and chroma of 0 to 2
It is silty clay or clay
iLeOn Series
` The Leon series consists of poorly drained soils on
uplands The soils formed in coarse textured sediment
Slopes are less than 1 percent
Typical pedon of Leon fine sand is 2 2 miles south of
Grissettown, 1 6 miles west of the intersection of N C
Highway 904 and State Road 1163, 50 feet south of
State Road 1163
A-0 to 6 inches, dark gray (10YR 4/1) fine sand, single
grained, loose, about 1 /3 sand grains are uncoated,
common medium and fine roots, extremely acid,
clear wavy boundary
E-6 to 14 inches, light gray (10YR 7/1) fine sand,
single grained, loose, very strongly acid, clear wavy
boundary
61
Bh1-14 to 17 inches, black (5YR 211) fine sand,
massive friable weakly cemented, very strongly
acid gradual wavy boundary
Bh2-17 to 23 inches, dark reddish brown (5YR 3/3)
fine sand, few medium faint black (5YR 2/1)
mottles, massive, friable weakly cemented, very
strongly acid clear irregular boundary
E'-23 to 30 inches, light gray (10YR 7/1) fine sand,
single grained, loose very strongly acid, gradual
wavy boundary
B'h-30 to 35 inches black (5YR 2/1) fine sand,
massive, weakly cemented, very strongly acid,
gradual wavy boundary
E"-35 to 42 inches brown (10YR 4/3) fine sand single
grained loose, very strongly acid, gradual wavy
boundary
B"h1-42 to 72 inches, black (5YR 2/1) fine sand,
massive weakly cemented very strongly acid,
gradual wavy boundary
B h2-72 to 80 inches, dark gray (5YR 4/1) fine sand
massive weakly cemented, very strongly acid
The sandy horizons are 80 inches thick or more The
soil is extremely acid or very strongly acid throughout,
unless the surface layer has been limed
The A or Ap horizon has hue of 10YR value of 2 to 4
and chroma of 1
The E horizon has hue of 10YR value of 5 to 8 and
chroma of 1 or 2 Texture is sand or fine sand
The Bin horizon has hue of 5YR or 10YR value of 2 or
3, and chroma of 1 to 3 Texture is fine sand or sand
The lower E', B'h E , and B"h horizons have hue of
5YR to 1 OYR, value of 2 to 7, and chroma of 1 or 2
Texture is sand or fine sand
Lumbee Series
The Lumbee series consists of poorly drained soils on
stream terraces The soils formed in moderately fine
textured sediment Slopes are 0 to 2 percent
Typical pedon of Lumbee fine sandy loam, 1 mile
northwest of Regan, 1 4 miles northeast of the
intersection of N C Highway 904 and forest road 30 feet
north of forest road
A-0 to 6 inches, very dark gray (10YR 3/1) fine sandy
loam, weak medium granular structure very friable,
common fine roots, very strongly acid clear wavy
boundary
E-6 to 18 inches light brownish gray (10YR 6/2) fine
sandy loam weak medium granular structure, very
friable common fine roots, very strongly acid, clear
wavy boundary
Btg1-18 to 28 inches gray (10YR 6/1) sandy clay
loam, few medium prominent red (2 5YR 5/8)
mottles and common medium distinct brownish
yellow (10YR 6/8) mottles, weak fine subangular
�l
o4
Muckalee Series
The Muckalee series consists of poorly drained soils
on low flood plains The sods formed in moderately
coarse textured recent alluvium Slopes are 0 to 2
percent
Typical pedon of Muckalee loam, 1 3 miles southwest
of Waccamaw 08 mile northeast of the intersection of
State Road 1321 and State Road 1322 250 feet west of
State Road 1321
A-0 to 6 inches very dark grayish brown (10YR 3/2)
loam, weak fine granular structure friable, many fine
roots, strongly acid gradual wavy boundary
Cg1-6 to 22 inches, grayish brown (10YR 5/2) loamy
sand, common medium faint light brownish gray
(10YR 6/2) mottles, single grained, very friable,
common fine roots, medium acid, gradual wavy
boundary
Cg2-22 to 36 inches, gray (10YR 6/1) sandy loam that
has lenses of sandy clay loam, few medium distinct
yellowish brown (10YR 5/6) and strong brown
(7 SYR 5/8) mottles, massive, friable, few fine and
medium roots, medium acid, gradual wavy boundary
,g3-36 to 65 inches, gray (10YR 6/1) loamy sand that
has strata of sandy loam, common medium distinct
strong brown (7 SYR 5/6) and light olive brown
(2 5Y 5/6) mottles and few medium distinct greenish
gray (5G 5/1) mottles, massive friable, slightly acid
The loamy or sandy horizons are 40 inches thick or
more The sod ranges from strongly acid to slightly acid
in the A horizons and medium acid to neutral in the
underlying matenals
The A horizon has hue of 10YR, value of 3 to 5 and
chroma of 1 or 2
The Cg horizon has hue of 10YR or 5Y, value of 3 to
7, and chroma of 1 or 2 The Cg horizon is generally
sandy loam that has fragments of marl in the lower part
Texture includes sand, loamy sand, loam, fine sandy
loam and thin layers of sandy clay loam
Murvdle Series
The Murvdle series consists of very poorly drained
soils in depressions on uplands The soils formed in
coarse textured sediment with an abundance of organic
matter Slopes are 0 to 2 percent
Typical pedon of Murville mucky fine sand, 1 2 miles
southeast of Boiling Spring Lake, 0 2 mile northwest of
the intersection of N C Highway 133 and N C Highway
87 35 feet east of N C Highway 133
A-0 to 5 inches, black (5YR 2/1) mucky fine sand,
weak medium granular structure, very friable
common medium and fine roots extremely acid,
gradual wavy boundary
Sod Survey
Bh1-5 to 35 inches black (5YR 2/1) fine sand,
massive very friable, few large roots, sand grams
are coated with organic matter and feel loamy,
extremely acid gradual wavy boundary
Bh2-35 to 55 inches, dark reddish brown (5YR 3/2)
fine sand, massive, very friable, sand grains are
coated and bridged with organic matter and feel
loamy, extremely acid, gradual wavy boundary
Bh3-55 to 60 inches, dark reddish brown (5YR 2/2)
fine sand, massive, very friable, extremely acid
gradual wavy boundary
Bh4-60 to 80 inches, dark reddish brown (5YR 3/2)
fine sand massive, very friable, extremely acid
The sandy horizons are 80 inches thick or more The
sod ranges from extremely acid to strongly acid
throughout, unless the surface layer has been limed
The A horizon has hue of SYR to 10YR value of 2 or
3, and chroma of 1 or 2
The Bh horizon has hue of SYR to 10YR, value of 2 or
3, and chroma of 1 or 2 Sand grains are coated with
organic matter and have a soft, loamy feel Texture is
fine sand or sand
The Cg horizon, where present, has hue of 10YR,
value of 5 to 7, and chroma of 1 to 4 Mottles are in
shades of these colors Texture ranges from sand to
sandy clay loam
Newhan Series
The Newhan senes consists of excessively drained
sods on the Outer Banks The sods formed in coarse
textured eolian and marine sediments Slopes are 2 to
30 percent.
Typical pedon of Newhan fine sand 2 to 30 percent
slopes, on Ocean Isle Beach, 0 7 mile west of the
intersection of N C Highway 904 and State Road 1144
50 feet north of State Road 1144
A-0 to 1 inch, grayish brown (10YR 5/2) fine sand
single grained, loose, mildly alkaline, clear wavy
boundary
C-1 inch to 80 inches, light gray (10YR 7/2) fine sand
few fine faint pale brown (10YR 6/31 mottles single
grained, loose, common dark minerals, few shell
fragments, mildly alkaline
The sandy horizons are 80 inches thick or more The
soil is neutral or mildly alkaline throughout The silt plus
clay content is less than 5 percent Calcareous shell
fragments range from 0 to 25 percent of the sod volume,
and the soil has few to common grains of dark minerals
The A horizon, where present, has hue of 10YR value
of 5 or 6, and chroma of 1 or 2
The C honzon has hue of 11 OYR, value of 7 or 8, and
chroma of 1 or 2 Texture is fine sand or sand
Brunswick County North Carolina
TABLE 17 --PHYSICAL AND CHEMICAL PROPERTIES OF THE SOILS --Continued
Map symbol and IDepth'Clay 1 Moist I Permea- 1Awailable1 Soil 1Salinity'Shrink-swe
so 11 name bulk bll lty water �reactioni I potential
Jo ---------------I 0-131 5-1511 45-1 651 2.0-6 0 10 10-0 15'4. 5-5 5
Johns I13-38118-3511.40-1 601 0 6-2.0 10 12-0 L514 5-5 5
138-70' 2-1011 60-1 751 6 0-20 10 03-0 D614 5-5 5
KcB- =- -- --�1 0-861 0-3 11 60-1 801 6.4-20 -1 <0 OS 14 5-7 3
`Kureb
LA --------------- 1 0-551 --- 10 05-0.501 2 0-6 0 10 20-0 5013.6-8.4
Lafitte 155-72130-8510 50-1 OOi <0 06 10 15-0 2016.1-8.4
- 0-
Lo----------- -1 0-B0I 1-6 11 40-1.651 6 -20 10 02-0 OS 3.6-5.5
-fin �-_JI---�----�--'- I-- - -�- - �-- --
Lu--------------- 1 0-181 4-1811 55-1. 701 2 0-6 0 10 08-0 1214 5-5.5
Lumbee 118-38I18-3511 30-1.451 0 6-2 0 10 12-0 1614 5-5.5
I38-801 1-1011 60-1.751 6 0-20 10 03-0.06i4 5-5.5
Ly--------------- 1 0-161 5-2011 30-1 601 2 0-6 0 10 09-0 1313.6-5.5
Lynchburg 116-80118-3511.30-1 501 0 6-2 0 10 12-0 1613 6-5.5
Ma --------------- 1 0-181 <3 11 35-1 651 6 0-20 10.03-0 0713 6-6.0
Mandarin 118-351 2-9 IL 45-1 601 0 6-20 10.30-0 1513.6-6 0
135-621 <3 11 35-1. 451 0 6-26 10.03-0 0714 5-7 3
162-801 2-9 11 45-1 601 0 6-20 l0.10-0 1514.5-7 3
rHk------------------ 1 0-6 110-251 --- -1 0 6-2 0 10.09-0. 15Z 15 1-3
',Muckalee 1 6-651 5-201 --- i 0 6-2 0 10 08-01215 6-8.4
Mv-------- ----1 0-5 1 2-8 11 20-1 401 6 0-20 10 15-0. 2013.6-5 5
Murvllle 1 5-801 2-8 11.60-1 751 2 0-6 0 10 05-0 0913 6-5 5
NeE, NbE--------- 1 0-801 --- 11 60-1 75i >20 1 <0.05 13 6-7 8
Newhan
NoB -------------- 1 0-161 2-8 11 55-1 751 6 0-20 10 06-0. 1114 5-6 C
Norfolk 116-63118-3511 35-1 451 0 6-2.0 10 10-0 1514.55-5 5
63-90 -
On --------------- 1 0-171 5-1511 45-1 651 2 0-6 0 10 11-0.1513 6-5.5
Onslow 117-65115-3511 3D-1 501 0 6_2.0 10 12 0 17 i3.6 5 5
65-80
PaA-------------- 1 0-551 2-1211 60-1 751 6 0-20 10 05-0 1014.5-6.0
Pactolus i55-801 2-1211 60-1 75i 6 0-20 10 03-0 0714 5-5.'.
Pn--- ------------1 0-111 5-1511 2D-1 401 2 0.6.0 10 20-0. 3013 6-5 5
Pantego 111-15118-3511 30-1 401 0 6-2'0 10 12-02013.6-5.`.
15-80!18-401,1 25-1 4011 0 6-2.0 !0 15-0 2013 6-5.5
Pt 1
Pits 1
I
Ra---------------I 0-15
Rains 15-72
72-80
TM_______________i 0-12
Tomahawk ,12-23
5-201 30-1 60' 2 0-6.0 10 30-0 14'4 5-6.5
18-3511 30-1 501 0 6-2*0 10 11-0 1514 5-5.5
18-4011 30-1 501 0 6-2 0 10 10-0 1514 5-5.5
2-8 1160-1 751 6 0-20 10.04-0 1014 5-5 5
5-1511:45-1 651 2.0-6 0 10. 10-0 1414 5-5 5
2-8 11 60-1.751 6 0-20 !0.04-0 0814 5-6 5
K
os cm
1
<2
12
ILow--------- 10. 20
ILow--------- 10 24
<2
ILow--------10.10
<2
`Low --------- 10 10
4-8
8-16
I I
lyow-________I____
lHigh-------- I0.32
<2
'Low --------- 10.10
<2
<2
ILow--------- 10. 24
'Low ------ --10 32
<2
'Low ----- ----i0.10
<2
<2
ILow--------- 1D. 20
1Low--------- 10.20
---
-_-
ILow--------- 10. 10
1Low-------- 10 15
---
ILOw__------- 10 10
ILow--------- 10 IS
<2
<2
ILow--------- 10. 20
ILow--------- 10 20
<2
<2
ILow--------- 10 10
±Low---------10.10
<2
ILow--------- 10 10
<2
<2
'Low --------- 10.20
Low --------- !0 24
<2 ILow_________ 10 20
<2 114w---------.0.24
<2 ILow--------- 10 10
<2 ! Low_________ 10 10
1 <2 ILow--------- 10 10
1 <2 ILow---------- 10 28
1 <2 !Low --------- 10 28
0.20
0 24
0 28
0 10
0 15
0 10
5
5
5
5
5
-5-
5
5
5
5
4
5
5
5
5
115
matter
.5-2
<2
30-70
5-4
2-4
5-5
-3-
I 9-20
i 5-2
I
I
.5-2
I
I
.5-2
I
10-15
Appendix C
Table-1 (Ponds #12 & #21)
Table-2 (Ponds #12 & #21)
P \809\809-02\Calcs\Stonn\SHW'I ISSUE\Engineer's Repon REV 34-09 doc I 1
e
Pond #12
Table-1 Weighted Average Hydraulic Conductivity for various Sod Types
Soil Type = Lo, Leon
Depth D
p ( )
Hydraulic
Avg Conductivity
D x Kav
Conductivity (K)
in Depth Range(Kavg)g
m)
in/hr
in/hr
in^2/hr
0 - 80
6 - 20
13 0
1040 0
Weighted Kavg=
Soil Type =
1300 m/hr
KrB, Kureb
L= 1U4UU
Weighted Kavg = F(Di x Kavg)
Dtot
Depth (D)
Hydraulic
Avg Conductivity
x Kavg
Conductive (K)
in Depth Range (Kavg)D
m
in/hr
(m/hr)in^2/hr
0 - 80
6 - 20
13 0
1040 0
Weighted Kavg=
L= 1U4UU
13 00 in/hr Weighted Kavg = F(Di x Kavg)
Dtot
Table-2 Weighted Average Hydraulic Conductivity for Pond#12
Soil Type
Weighted Kavg
Linear Feet of
Normal Pool
Avg x LF
n/hr
ft
in/hr x ft
Lo Leon
1300
1089
1415700
KrB, Kureb
1300
131
170300
1220 1586000
Weighted Average = 13 m/hr F(Kavg x LF)
Weighted Average = 7(LF)
Pond #21
Table-1 Weighted Average Hydraulic Conductivity for various Sod Types
Soil Type = Mk, Muckalee
Depth (D)
Hydraulic
Conductive (K)
Avg Conductivity
in Depth Range(Kavg)D
x Kavg
in
m/hr
in/hr
W2/hr
0 - 6
06 - 2
13
78
6 - 65
06 - 2
1 3
767
E= 78
Weighted Kavg= 1 30 in/hr Weighted Kavg = E(Di x Kavg)
Dtot
Table-2 Weighted Average Hydraulic Conductivity for Pond#21
Soil Type
Weighted Kavg
Linear Feet of
Avg x LF
Normal Pool
in/hr
ft
in/hr x ft
Mk, Muckalee
1 30
1515
196950
1515 196950
Weighted Average = 13 m/hr Weighted Average = F(Kavg x LF)
E(LF)
Appendix D
Table-3 (Ponds #12 & #21)
Sample Calculations-1
P \809\809 02\Calcs\Storrn\SIIWT ISSUE\Engmeers Report REV 3-4 09 doc 12
Pond #12
Table-3 Groundwater Flow into Pond#12 During SHWT Conditions (from Darcy's Eqn )
SHWT =
3842
ft msl
Normal Pool =
36
ft msl
K =
1300
in/hr
(1)
Elevation
(2)
Contour Area
(3)
X-Sectional Area
(4)
dh
L
(5)hOO
ft
W2
(ft-2)ft
ft
3842
108603
--
--
--38
106979
1624
042
350
37
103170
3809
1 42
350
36
95110
8060
242
350
35
87312
7798
242
350
0 016
34
83803
3509
242
350
0 007
33
80349
3454
242
350
0 007
32
76951
3398
242
350
0 007
31
73609
3342
242
350
0 007
30
70323
70323
242
350
0 146
Total Groundwater Flow into Pond (Qgw) = 0 213 cfs
Pond #21
Table-3 Groundwater Flow into Pond#21 During SHWT Conditions (from Darcy's Eqn )
SHWT =
908
ft mSl
Normal Pool =
6
ft mSl
K =
1 30
inlhr
(1)
Elevation
(2)
Contour Area
(3)
X-Sectional Area
(4)
dh
L
(5)h0027
ft
ft-2
(ft-2)ft
ft
908
71286
--
--
--9
70873
413
008
35
8
65846
5027
1 08
35
7
60952
4894
208
35
6
50795
10157
308
35
5
41255
9540
308
35
0 025
4
37059
4196
308
35
0 011
3
32996
4063
308
35
0 011
2
29071
3925
308
35
0 010
1
25288
3783
308
35
0 010
0
21656
3632
308
35
0 010
-1
18164
3492
308
35
0 009
-2
14513
3651
308
35
0 010
-3
11968
2545
308
35
0 007
-4
9653
2315
308
35
0 006
-5
7551
2102
308
35
0 006
-6
5658
1893
308
35
0 005
-7
3970
3970
308
35
0 011
Total Groundwater Flow into Pond (Qgw) = 0 170 cfs
Sample Calculations-1
The following sample calculations correspond to Table-3
(1) Elevation (E) — this elevation corresponds to the incremental contour elevation in the pond
(2) Contour Area (SA) — Contour Surface Area at E(,)
(3) Contributing Area (A) — Cross Sectional Area between elevation E(,) and E), 1)
A(,) = SA(, 1) - SA(j)
(4) Head Differential (dh)
For E(,) > Normal Pool Elevation
dh = E(, O) - E(,) (E(, o) = SHWT elevation)
For E(,) <Normal Pool Elevation
dh — E(, O) — Normal Pool Elevation
(5) Length (L) — Hydraulic Length Length over which the head differential acts
(6) Incremental Flowrate (Q) — inflow of ground water through the cross sectional area between
elevation E(,) and E(, 1)
Q = KA (dh/L) Where, K = weighted average hydraulic conductivity (See Table-2)
A = See Column 3
dh = See Column 4
L — See Column 5
Appendix E
Pond #12 & #21 Design Calculations
Pond Routing Data
P \80%809-02\Calcs\Storm\SI-IWT ISSUE\Engmeers Report REV 34-09 doe 13
WET DETENTION BASIN DATA SHEET
OCEAN ISLE PALMS PHASE I A
POND # 12
DRAINAGE AREA (Ad) _
IMPERVIOUS AREA (Ai)
BUILDINGS
ROADS
SIDEWALKS
CK CLUB
CONTINGENCY
24 82 ACRES
10 19 ACRES
2 19 ACRES
0 02 ACRES
0 OG ACRES
0 07 ACRES
TOTAL 12 53 ACRES
PERCENT IMPERVIOUS (1)
I = Ad/Ai = 50 47%
POND # 12 SHALL BE G' DEEP WITH
AN AVG DEPTH OF 5' AND DESIGNED TO REMOVE 90% T55
SA/DA= 3 54%
REQUIRED SURFACE AREA AT PERMANENT POOL
74 LOTS @ GOOO SF/LOT
ALLEY WAYS
SA�ZEQ = 0 8778634 AC = 3824 1 SF
SURFACE AREA PROVIDED AT PERMANENT POOL (EL 3G)= 951 10 SF
SA PROV'D= 951 10 > 3824 1 =5A REQ'D OK
MINIMUM REQUIRED VOLUME (SIMPLE METHOD BY TOM SCHUELER)
Rv=O 05+0 009'(1) Rv= (0 05+0 009.50 47)
Rv= 050423
VOLUME= I '*Rv*AcI = 1 04292 AC -FT
45429 FT^3
VOLUME PROVIDED AT TEMPORARY POOL
INCREM
TOTAL
EL
SA (5F)
VOL, (CF)
VOL, (CF)
3G
55110
0
0
37
103170
99139 9
99139 9
38
IOG979
105075
204215
39
110845
106912
313127
40 1147GG 112805 425932
41 123174 118970 544902 108G03
SET TEMP POOL ELEVATION
REQ'D EL = 3G 4G f-5AY 38 00'
VOL PROV'D = 204215 CF
VOL PROV'D= 204215 > 45429 =VOL REQ'D
OK
FOREBAY SIZING THIS POND WILL HAVE TWO FOREBAY5 ONE WILL FILTER 94%
AND THE OTHER FOREBAY, G% OF THE ENTIRE DRAINAGE BA51N
PERMANENT POOL VOLUME
INCREM
TOTAL
EL,_
5A (5F)
VOL (CF)
VOL. (CF)
30
70323
0
0
31
73GO9
719GG
719GG
32
7G951
75280
14724G
33
80349
78G50
22569G
34
53803
6207G
307971
35
67312
85556
393529
3G
95110
91211
484740
F5A � DEPTH REQ MET
4- AVE DEPTH = VOL / 5A
= 5 09GG5
REQ'D VOLUME = 20% OF VOL TOTAL AT MIN REQ'D 5A AND DEPTH =
94 4% REQ'D VOLUME EAST FOREBAY= 42G49 I CF
5 G% REQ'D VOLUME WEST FOREBAY= 2530 CF
CHECK FOREBAY VOLUME
EASTERN FOREBAY
INCREM
TOTAL
EL.
5A (5F)
VOL, (CF)
VOL, (CF)
30
5758
0
0
31
G823
G310
G310
32
7915
73G9
13G79
33
9073
5494
22172
34
10298
9G85
31858
35
11590
10944
42802
42802 CP 5 O' DEEP FOREBAY
45179
42802 42G49
VOL PROV'D= 42802 42G49 =VOL REQ'D OK
CHECK FOREBAY VOLUME
WESTERN FOREBAY
INCREM TOTAL
FL.
SA (5F)
VOL. (CF) VOL. (CF)
30
34
0 0
31
144
89 89
32
332
238 327
33
597
4G4 791
34
940
7G9 15G0
35
13G0
1150 2710
2710
CF 5 0' DEEP FOREBAY
2710
= 2530
VOL PROV'D=
2710
2530 =VOL REQ'D OK
ORIFICE 51ZING REQ'D DRAWDOWN TIME = 2-5 DAYS
STEP # I DETERMINE THE ALLOWABLE RANGE OF FLOWRATES
(SHWT CONDITIONS NOT PRESENT)
Qz = 0 2G290 CF5 (FOR 2 DAY DRAWDOWN)
Q5 = 0 105 1 G CF5 (FOR 5 DAY DRAWDOWN)
NOTE THE NORMAL POOL 15 MORE THAN G-INCHES BELOW THE ESTIMATED SHWT THE
ORIFICE MUST BE EVALUATED TO EFFECTIVELY DEAL WITH THE INFLOW OF
GROUNDWATER AND DRAWDOWN THE DE51GN STORM VOLUME IN 2-5 DAYS
TFP #2 QUANTIFY THE AMOUNT OF GROUND WATER EXPECTED TO ENTER THE POND UNDER
SHWT CONDITIONS (SEE ATTACHED CALCULATIONS)
Qgw = 0 2 13 CF5
STEP #3 SELECT ORIFICE SIZE
ORIFICE DIA = 30 IN
STEP #4 DETERMINE ELEVATION IN POND DUE TO INCOMING GROUNDWATER FLOW
(STEADY STATE HEAD TO PA55 GROUNDWATER)
Q9w = Cd'A'(2'g'hyw) � 112
h9w= 081214
ELEV9w = 3G 90
WHERE Cd= 0 G
A= 0 04909 51'
g= 322 FP5/5
h= head read for Q9w
STEP #5 DETERMINE REQUIRED ELEVATION ABOVE ELEVATION DUE TO GROUNDWATER
MIN REQ'D VOLUME = 78,G50 CF
INCREM
TOTAL
fl .
5A (51)
VOL (CP)
VOL, (CF)
3G 2
9G,722
0
0
37
103,170
79,957
79,957
38
1 OG,979
105,075
185,032
MIN REQ'D ELEVATION = 3G 99
TEMP POOL ELEV (ELEVTP) = 38 00 (OUTLET STRUCTURE ELEVATION)
STEP #G DETERMINE THE ALLOWABLE RANGE OF FLOWRATES
(SHWT CONDITIONS PRESENT)
Qz + Q9w = 0 47590 CF5
Q5 + Q9w = 0 3 181 G CF5
STEP #7 DEMONSTRATE ORIFICE ACCOMMODATES STEADY STATE GROUNDWATER * Q2-Q5
QTOT= Ca'A'(2'g'hAVG) ^ 1 /2
QTOT= 0 27G
WHERE Cd= 0 G
A= 0 04909 51'
g= 32 2 FP5/5
h AVG= ELEVTP - ELEV9w + h9w
2
= 13G214 FT
Q2 + Qgw < 0 27G < Q5 + Qgw NG
STEP #8 DETERMINE DRAWDOWN TIME
Qd = Discharge of Design Volume
Qdv = QTOT - Qgw = O OO CFS
DRAWDOWN TIME
TIME = VOLUME = 14 48 DAYS
Qdv
WET DETENTION BASIN DATA SHEET
OCEAN ISLE PALMS -PHASE I
POND #21
DRAINAGE AREA (Ad) =
21 I G ACRES
IMPERVIOUS AREA (Ai)
BUILDINGS
482 ACRES (35 LOTS@ G OOOSF/LOT)
ROADS
3 G4 ACRES
AMENITY CENTER
2 15 ACRES
OFF -SITE
0 00 ACRES
CONTINGENCY
0 50 ACRES ALLEY WAY
TOTAL II II ACRES
PERCENT IMPERVIOUS (1)
I = Ai/Ad = 52 5 1 %
POND#2 1 SHALL BE 13 0' DEEP WITH AN AVG DEPTH OF 5 5'* DESIGNED TO REMOVE 90% T55
SA/DA= 3 30%
REQUIRED SURFACE AREA AT PERMANENT POOL
SAKEQ= 0 G9825 AC = 30417 SF
SURFACE AREA PROVIDED AT PERMANENT POOL (EL G 0')= 50795 SF
5A PROV'D= 50795 > 304 17 =SA REQ'D OK
MINIMUM REQUIRED VOLUME (SIMPLE METHOD BY TOM SCHUELER)
Rv=O 05+0 000*(1)
Rv= 052259
VOLUME= I " Kv Ad = 0 92 15 AC -FT
40141 FT^3
VOLUME PROVIDED AT TEMPORARY POOL
INCREM TOTAL
fl 5A (5F) VOL (CF) VOL (GE)
G 50795 0 0
G 5 55874 2GGG7 20007
7 G0952 2920G 55874
8 G584G G3399 119273
9 70873 G53G0 187G32
10 7G030 73452 2GIO54
SET TEMP POOL ELEVATION
REQ'D EL = G 9G 4--- SAY 7 1'
VOL PROV'D = 622 1 3 CF
VOL PROV'D= 62213 > 40141 =VOL REQ'D OK
FOREBAY SIZING
PERMANENT POOL VOLUME
INCREM
TOTAL
EL
5A (5F)
VOL, (CF)
VOL (CF)
-7
3970
0
0
-6
5658
4814
4514
-5
7551
6605
11419
-4
9653
8602
20021
-3
11968
1081I
30831
-2
14513
13241
44072
-I
I8I64
16339
G0410
0
21656
19910
80320
I
25288
23472
103792
2
29071
27180
130972
3
32996
31034
IG2005
4
37059
35028
197033
5
41255
35157
236190
5 5
43402
21164
257354
6
50795
23549
280903
REQ'D VOLUME =
20% TOTAL =
561 81
CF
CHECKFOREBAY VOLUME
< SURFACE AREA a
DEPTH REQ MET
AVE DEPTH = VOL / 5A
< = 5 53
NCREM
TOTAL
EL
SA (5F)
VOL (CF)
VOL (CF)
- 1
5939
0
0
0
7428
6684
6684
1
8980
8204
14888
2
10597
9789
24676
3
12278
11438
3GI14
5
14024
26302
62416
PROV'D VOLUME =
G24 16
CF 7DEEP
FOREBAY)
VOL PROV'D=
62416
=
56181 =VOL REQ'D
ORIFICE SIZING REQ'D DRAWDOWN TIME = 2-5 DAYS
STEP # I DETERMINE THE ALLOWABLE RANGE OF FLOWRATES
(SHWT CONDITIONS NOT PRESENT)
OK
QZ = 0 23229 CFS (FOR 2 DAY DRAWDOWN)
Q5 = 0 09292 CPS (FOR 5 DAY DRAWDOWN)
NOTE THE NORMAL POOL 15 MORE THAN 6-INCHE5 BELOW THE ESTIMATED SHWT
THE ORIFICE MUST BE EVALUATED TO EFFECTIVELY DEAL WITH THE INFLOW
OF GROUNDWATER AND DRAWDOWN THE DESIGN STORM VOLUME IN 2-5
DAYS
STEP #2 QUANTIFY THE AMOUNT OF GROUND WATER EXPECTED TO ENTER THE POND
UNDER SHWT CONDITIONS (SEE ATTACHED CALCULATIONS)
Qgw = 0 17 CF5
STEP #3 SELECT ORIFICE SIZE
ORIFICE DIA = 30 IN
STEP #4 DETERMINE ELEVATION IN POND DUE TO INCOMING GROUNDWATER FLOW
(STEADY STATE HEAD TO PASS GROUNDWATER)
Qyw = Cd'A (2 6j'h9j) 1/2
hyw = 0 5 1 733
ELEVgw = G GO
WHERE Cd= 0 G
A= 0 04909 SF
g= 32 2 FP5/5
h= head recq'd for Qyw
STEP #5 DETERMINE REQUIRED ELEVATION ABOVE ELEVATION DUE TO GROUNDWATER
MIN REQ'D VOLUME =
2G 921
CF
INCREM
TOTAL
EL. SA (SF)
VOL, (CF)
VOL (CF)
G G 5G 889
0
0
7 GO,952
23,5G8
23 5G8
8 G5,84G
G3 399
8G 9G7
MIN REQ'D ELEVATION =
7 05
TEMP POOL ELEV (ELEVTP) = 7 10 (OUTLET STRUCTURE ELEVATION)
STEP #G DETERMINE THE ALLOWABLE RANGE OF FLOWRATES
(SHWT CONDITIONS PRESENT)
Q2 + Qyw = 0 40229 CF5
Q5 + Qyw = 0 2G292 CF5
STEP #7 DEMONSTRATE ORIFICE ACCOMMODATES STEADY STATE GROUNDWATER E Q2-05
QTOT= Cd A*(2'6j'hAVG)^ 1/2
QTOT= 0207
WHERE Cd= O G
A= 0 04900 5F
g= 32 2 FPS/5
h AVG= ELEVTP - ELEVgw + hgw
2
= 0 7G7 FT
Q2 + Qgw < 0 207 < Q5 + Qgw NG
STEP #8 DETERMINE DRAWDOWN TIME
Qa = Discharge Of Design VOlume
Qd = OTOT - QJw = 004 CF5
DRAWDOWN TIME
TIME = VOLUME = 8 4 1 DAYS
Qdv
1
ED
2
4
5
7
o
$
Legend
Hvd Origin
Description
1 SCS Runoff
POST DEVELOPMENT POND 12
-
2 Reservoir
SCS POND 12 R
4 SCS Runoff
EX STUMP POND
5 Reservoir
STUMP POND ROUTING
7 SCS Runoff
POST DEVELOPMENT POND 21
8 Reservoir
SCS POND 21 R -
Hydraflow Hydrographs Model
Project SHWT ISSUE 1-12-09 gpw
Monday Jan 12 2009, 4 18 PM
Table of Contents
SHWT ISSUE 1-12-09 gpw
Hydraflow Hydrographs by Intelisolve
1 -Year
Summary Report
Hydrograph Reports
Hydrograph No 1, SCS Runoff, POST DEVELOPMENT POND 12
Hydrograph No 2, Reservoir, SCS POND 12 R
Pond Report
Hydrograph No 4, SCS Runoff, EX STUMP POND
Hydrograph No 5, Reservoir, STUMP POND ROUTING
Pond Report
Hydrograph No 7, SCS Runoff, POST DEVELOPMENT POND 21
Hydrograph No 8, Reservoir, SCS POND 21 R
Pond Report
Monday Jan 12 2009 4 17 PM
2
2
3
4
Hydrograph Summary Report
Hyd
No
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
peak
(min)
Volume
(cult)
Inflow
hyd(s)
Maximum
elevation
W
Maximum
storage
(cuft)
Hydrograph
description
1
SCS Runoff
4300
2
734
189 998
—
POST DEVELOPMENT POND 12
2
Reservoir
030
2
1454
81 293
1
3775
177 487
SCS POND 12 R
4
SCS Runoff
7805
2
762
629 375
—
- -
- -
EX STUMP POND
5
Reservoir
6305
2
780
629 372
4
3548
287 154
STUMP POND ROUTING
7
SCS Runoff
2969
1
759
217 714
—
— —
— —
POST DEVELOPMENT POND 21
8
Reservoir
420
1
898
161 161
7
813
129 249
SCS POND 21 R
SHWT ISSUE 1-12-09 9PW
Return Period 1 Year
Monday, Jan 12 2009, 4 17 PM
Hydraflow Hydrographs by Intelisolve
Hydrograph Plot 2
Hydraflow Hydrographs by Intelisolve
Monday Jan 12 2009 4 17 PM
r
Hyd No 1
POST DEVELOPMENT POND 12
Hydrograph type
= SCS Runoff
Peak discharge =
43 00 cfs
Storm frequency
= 1 yrs
Time Interval =
2 min
Drainage area
= 24 820 ac
Curve number =
84
Basin Slope
= 1 5 %
Hydraulic length =
850 ft
Tc method
= LAG
Time of conc (Tc) = 20 00 min
Total precip
= 3 70 in
Distribution =
Type III
Storm duration
= 24 hrs
Shape factor =
484
Q (cfs)
5000
U1211111
3000
2000
1000
000
POST DEVELOPMENT POND 12
Hyd No 1 -- 1 Yr
Hydrograph Volume = 189 998 cult
Q (cfs)
5000
4000
3000
2000
1000
000
0 2 5 7 9 12 14 16 19 21 23 26
Hyd No 1 Time (hrs)
--
3
Hydrograph Plot
Hydraflow Hydrographs by Intelisolve Monday Jan 12 2009 4 17 PM
Hyd No 2
SCS POND 12 R
Hydrograph type = Reservoir Peak discharge = 0 30 cfs
Storm frequency = 1 yrs Time Interval = 2 min
Inflow hyd No = 1 Max Elevation = 37 75 ft
Reservoir name = Pond #12 Max Storage = 177,487 cuft
Storage Indication method used
Q (cfs)
5000
4000
3000
2000
IDIOM
SCS POND 12 R
Hyd No 2 -- 1 Yr
Hydrograph Volume = 81 293 cult
Q (cfs)
5000
4000
3000
2000
1000
000 000
0 10 19 29 39 48 58 68 77 87 97
Time (hrs)
— Hyd No 2 —Hyd No 1
Pond Report
Hydraflow Hydrographs by Intellsolve Monday Jan 12 2009 4 17 PM
Pond No 1
- Pond #12
Pond Data
Pond storage
is based on known
contour areas Average end area method
used
Stage / Storage Table
Stage (ft)
Elevation (ft)
Contour area (sqft)
Incr Storage (cuft)
Total storage (cuft)
000
3600
95 110
0
0
100
3700
103 170
99 140
99 140
200
3800
106 979
105 075
204 215
300
3900
110 845
108 912
313 127
400
4000
114 776
112 811
425 937
500
41 00
118 744
116 760
542 697
600
4200
122 767
120 756
663 453
Culvert I Orifice Structures
Weir Structures
[A]
[B]
[C]
[D]
[A] IB]
[C]
[D]
Rise (in)
= 1800
300
000
000
Crest Len (ft)
= 12 00 1200
000
000
Span (in)
= 1800
300
Goo
000
Crest El (ft)
= 38 00 3850
000
000
No Barrels
= 1
1
0
0
Weir Coeff
= 333 333
000
000
Invert El (ft)
= 3558
3600
000
000
Weir Type
= Riser Rect
--
-
Length (ft)
= 63797
000
000
000
Multi Stage
= Yes No
No
No
Slope (%)
= 0 10
000
000
000
N Value
= 013
013
013
000
Orif Coeff
= 060
060
060
000
Multi Stage
= n/a
No
No
No
Exfiltration = 0 000 in/hr (Contour) Tatlwater Elev = 0 00 ft
Note CulveNOnfice cuHlow have been analyzed under inlet and outlet control
Stage (ft) Stage / Discharge stage (ft)
600
500
400
300
200
1 00
000
600
500
400
300
200
1 00
000
000 3000 6000 9000 12000 15000 18000 21000 24000 27000 30000
— Total 0 Discharge (cfs)
5
Hydrograph Plot
Hydraflow Hydrographs by Intelisolve
Monday Jan 12 2009 4 17 PM
Hyd No 4
EX STUMP POND
Hydrograph type
= SCS Runoff
Peak discharge
= 78 05 cfs
Storm frequency
= 1 yrs
Time Interval
= 2 min
Drainage area
= 214 420 ac
Curve number
= 64
Basin Slope
= 0 3 %
Hydraulic length
= 4788 ft
Tc method
= KIRPICH
Time of conc (Tc)
= 47 99 min
Total precip
= 3 70 in
Distribution
= Type III
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
8000
7000
6000
5000
4000
3000
2000
1000
000
EX STUMP POND
Hyd No 4 -- 1 Yr
Hydrograph Volume = 629 375 cult
Q (cfs)
8000
7000
6000
1611I1U:
[[111I1:
[K11111111,
2000
1000
000
0 2 5 7 9 12 14 16 19 21 23 26
Time (hrs)
— Hyd No 4
6
Hydrograph Plot
Hydraflow Hydrographs by Intelisolve
Monday Jan 12 2009 4 17 PM
Hyd No 5
STUMP POND ROUTING
Hydrograph type = Reservoir
Peak discharge
= 63 05 cfs
Storm frequency = 1 yrs
Time Interval
= 2 min
Inflow hyd No = 4
Max Elevation
= 35 48 ft
Reservoir name = EX STUMP POND
Max Storage
= 287,154 cuft
Storage Indication method used Wet pond routing start elevation = 35 00 ft
Hydrograph Volume = 629 372 cult
STUMP POND ROUTING
Q (cfs) Hyd No 5 -- 1 Yr Q (cfs)
8000
7000
6000
5000
4000
3000
2000
1000
0 00
8000
7000
6000
5000
4000
3000
2000
1000
000
0 3 5 8 11 13 16 19 21 24 27
— Hyd No 5 — Hyd No 4 Time (hrs)
Pond Report
Hydraflow Hydrographs by Intellsolve
Monday Jan 12 2009 4 17 PM
Pond No 5 - EX STUMP POND
Pond Data
Pond storage Is based on known contour areas
Average end area method used
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (scift) Incr Storage (cult)
Total storage (cuft)
000 3400 187 690
0
0
1 00 3500 195 169
191 430
191 430
200 3600 203 268
199 219
390 648
300 3700 212 677
207 973
598 621
400 3800 224 600
218 639
817 259
500 3900 253 176
238 888
1 056 147
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[D]
[A]
[B]
[C]
[D]
Rise (in)
= 6000
000
000
000
Crest Len (ft)
= 56 70
3000
000
000
Span (in)
= 6000
000
000
000
Crest El (ft)
= 35 00
3700
000
000
No Barrels
= 3
0
0
0
Weir Coll
= 333
333
000
000
Invert El (ft)
= 2996
000
000
000
Weir Type
= Riser
Clplti
--
--
Length (ft)
= 13500
000
000
000
Multi -Stage
= Yes
No
No
No
Slope (%)
= 074
000
000
000
N Value
= 013
000
000
000
Orif Coeff
= 060
000
000
000
Multi Stage
= n/a
No
No
No
Exftltration = 0
0001n/hr (Contour) Tailwater Elev = 0 00 It
Stage (11)
500
400
300
200
1 00
000
Stage / Discharge
Note CulverYOnfice outflows have been analysed under inlet and outlet control
Stage (ft)
500
400
300
200
1 00
000
000 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000
— Total Q Discharge (cfs)
Hydrograph Plot
HydraFlow Hydrographs by Intehsolve
Hyd No 7
POST DEVELOPMENT POND 21
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Drainage area
= 30 660 ac
Basin Slope
= 1 0 %
Tc method
= USER
Total precip
= 3 70 in
Storm duration
= 24 hrs
Q (cfs)
3000
2500
2000
1500
1000
500
Monday Jan 12 2009 4 17 PM
Peak discharge = 29 69 cfs
Time Interval
= 1 min
Curve number
= 82
Hydraulic length
= 2275 ft
Time of conc (Tc)
= 57 60 min
Distribution
= Type III
Shape factor
= 484
POST DEVELOPMENT POND 21
Hyd No 7 -- 1 Yr
Hydrograph Volume = 217 714 cult
Q (cfs)
3000
2500
2000
1500
1000
6Y11);
mww
0 3 5 8 10 13 15 18 20 23 25
— Hyd No 7 Time (hrs)
8
men
n
Hydrograph Plot
Hydraflow Hydrographs by Intelisolve
Monday Jan 12 2009 4 17 PM
Hyd No 8
SCS POND 21 R
Hydrograph type
= Reservoir
Peak discharge
= 4 20 cfs
Storm frequency
= 1 yrs
Time interval
= 1 min
Inflow hyd No
= 7
Max Elevation
= 8 13 ft
Reservoir name
= POND #21
Max Storage
= 129,249 cuft
Storage Indication method used Hydrograph Volume = 161 161 cult
SCS POND 21 R
Q (cfs) Hyd No 8 -- 1 Yr Q (cfs)
3000 3000
2500 - - - - - ----- - -- - -- -- - - 2500
2000 2000
1500 1500
1000 1000
000 000
0 5 10 15 19 24 29 34 39 44 48
— Hyd No 8 — Hyd No 7 Time (hrs)
Pond Report
10
Hydraflow Hydrographs by Intellsolve
Monday Jan 12 2009 4 17 PM
Pond No 4 - POND #21
Pond Data
Pond storage Is based on known contour areas
Average end area method used
Stage / Storage Table
Stage (ft) Elevation (ft)
Contour area (sqft) Incr Storage (cult)
Total storage (cuft)
000 600
50 795
0
0
050 650
58 553
27 337
27 337
1 00 700
60 952
29 876
57 213
200 800
65 846
63 399
120 612
300 900
70 873
68 360
188 972
400 1000
76 030
73 452
262 423
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[D]
[A]
[B]
[C]
[D]
Rise (in)
= 800
300
000
000
Crest Len (ft)
= 3000
000
000
0 00
Span (in)
= 800
300
000
000
Crest El (ft)
= 890
000
000
000
No Barrels
= 3
1
0
0
Weir Coeff
= 333
000
333
000
Invert El (ft)
= 710
600
000
000
Weir Type
= CIPIb
—
—
—
Length (ft)
= 2500
000
000
000
Multi -Stage
= No
No
No
No
Slope (%)
= 1 00
100
000
000
N Value
= 013
013
000
000
Orif Coeff
= 060
060
000
000
Multi -Stage
= n/a
No
No
No
Exfiltration = 0 000 In/hr (Contour) Tallwater
Elev = 0 00 ft
Stage (ft)
400
300
200
1 00
Wil
Note CulverVOnfice outflows have been analyzed under inlet and outlet control
Stage / Discharge
Stage (it)
400
300
200
1 00
11IM11111111111
000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000
— Total C1 Discharge (cfs)
Table of Contents
SHWT ISSUE 1-12 09 gpw
Hydraflow Hydrographs by Intelisolve
100 - Year
Summary Report
Hydrograph Reports
Hydrograph No 7, SCS Runoff, POST DEVELOPMENT POND 21
Hydrograph No 8, Reservoir, SCS POND 21 R
Pond Report
Monday Jan 12 2009 4 18 PM
1
2
2
3
4
Hydrograph Summary Report
Hyd
No
Hydrograph
type
(origin)
Peak
flow
(CIS)
Time
interval
(min)
Time to
peak
(min)
Volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Maximum
storage
(cuft)
Hydrograph
description
1
SOS Runoff
15759
2
732
723 397
—
---
- - -
POST DEVELOPMENT POND 12
2
Reservoir
5406
2
756
589 768
1
39 61
381 833
SOS POND 12 R
4
SOS Runoff
62300
2
754
4 228 051
-
- —
- —
EX STUMP POND
5
Reservoir
54945
2
768
4 228 049
4
3735
675 894
STUMP POND ROUTING
7
SOS Runoff
11596
1
757
868 588
—
--
--
POST DEVELOPMENT POND 21
8
Reservoir
10682
1
769
808 558
7
989
254 477
SOS POND 21 R
i
SHWT ISSUE 1-12-09 gpw
Return Period 100 Year
Monday, Jan 12 2009, 4 18 PM
Hydraflow Hydrographs by Intelisolve
Hydrograph Plot 2
Hydraflow Hydrographs by Intelisolve
Hyd No 7
POST DEVELOPMENT POND 21
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Drainage area
= 30 660 ac
Basin Slope
= 1 0 %
Tc method
= USER
Total precip
= 10 00 in
Storm duration
= 24 hrs
Q (cfs)
12000
10000
OXIDE
4000
Pz1I1I111111
A
Monday Jan 12 2009 4 18 PM
c
d
0
Peak discharge
= 115 96 cfs
Time interval
= 1 min
Curve number
= 82
Hydraulic length
= 2275 ft
Time of conc (Tc)
= 57 60 min
Distribution
= Type III
Shape factor
= 484
POST DEVELOPMENT POND 21
Hyd No 7 -- 100 Yr
Hydrograph Volume = 868 588 cult
Q (cfs)
12000
10000
[:I8I1I11
4000
2000
WMT0
0 3 5 8 10 13 15 18 20 23 25
— Hyd No 7 ` Time (hrs)
Hydrograph Plot
HydraHow Hydrographs by Intelisolve
Monday Jan 12 2009 4 18 PM
Hyd No 8
SCS POND 21 R
Hydrograph type
= Reservoir
Peak discharge = 106 82 cfs
Storm frequency
= 100 yrs
Time Interval = 1 min
Inflow hyd No
= 7
Max Elevation = 9 89 ft
Reservoir name
= POND #21
Max Storage = 254,477 cuft
Storage Indication method used
Q (cfs)
12000
10000
Of 11
4000
2000
W"A
SCS POND 21 R
Hyd No 8 -- 100 Yr
Hydrograph Volume = 808 558 cult
Q (cfs)
12000
10000
[:11III111
4000
2000
MIMI
0 3 6 9 12 15 18 21 24 27 30 33
— Hyd No 8 — Hyd No 7 Time (hrs)
3
Pond Report
C!
Hydraflow Hydrographs by Intellsolve
Monday Jan 12 2009 4 18 PM
Pond No 4 - POND #21
Pond Data
Pond storage is based on known contour areas
Average end area method used
Stage / Storage Table
Stage (ft) Elevation (ft)
Contour area (sgft) Incr Storage (cuft)
Total storage (cult)
000 600
50 795
0
0
050 650
58 553
27 337
27 337
1 00 700
60 952
29 876
57 213
200 800
65 846
63 399
120 612
300 900
70 873
68 360
188 972
400 1000
76 030
73 452
262 423
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[D]
[A]
[B]
[C]
[D]
Rise (in)
= 800
300
000
000
Crest Len (ft)
= 30 00
000
000
000
Span (in)
= 800
300
000
000
Crest El (ft)
= 890
000
000
000
No Barrels
= 3
1
0
0
Weir Coeff
= 333
000
333
000
Invert El (ft)
= 710
600
000
000
Weir Type
= Clplti
—
—
—
Length (ft)
= 2500
000
000
000
Multi Stage
= No
No
No
No
Slope (%)
= 1 00
100
000
000
N-Value
= 013
013
000
000
C rif Coeff
= 060
060
000
000
Multi -Stage
= n/a
No
No
No
Exfiltration = 0
000 inthr (Contour) Tailwater Elev = 000111
Stage (ft)
400
300
200
100
000
I Note Culven/Onfce out lours have been anal zed under inlet and outlet control
Stage / Discharge
Stage (ft)
400
300
200
1 00
[�DU7•
000 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000
— Total 0 Discharge (cfs)
Appendix F
Jenny's Branch Channel Report
Using Hydraflow Express Extensions
P \809\809 02\Calcs\Storm\SHWT ISSUE\Engmcer s Report REV 34 09 doe 14
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 31D® 2008 by Autodesk Inc
Pond #21's Outfall into Ex Jinny's Branch
Trapezoidal
Bottom Width (ft)
= 5200
Side Slopes (z 1)
= 200,200
Total Depth (ft)
= 300
Invert Elev (ft)
= 500
Slope (%)
= 006
N-Value
= 0 030
Calculations
Compute by Known Q
Known Q (cfs) = 420
Elev (ft)
i:1<1i111
700
ME
500
400
Section
Monday Jan 12 2009
Highlighted
Depth (ft)
�0 20
Q (cfs)
= 4200
Area (sqft)
= 1048
Velocity (ft/s)
= 040
Wetted Perim (ft)
= 5289
Crit Depth, Yc (ft)
= 006
Top Width (ft)
= 5280
EGL (ft)
= 020
Depth (ft)
4 00
300
200
1 00
11 I
-1 00
Reach (ft)
0
Channel Report 11
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk Inc,
Pond #21's Outfall
into Ex Jenny's Branch
Trapezoidal
Bottom Width (ft)
= 5200
Side Slopes (z 1)
= 200,200
Total Depth (ft)
= 300
Invert Elev (ft)
= 500
Slope (%)
= 006
N-Value
= 0 030
Calculations
Compute by
Q vs Depth
No Increments
= 5
Elev (ft)
900
700
500
400
Section
Monday Jan 12 2009 I
t f
Highlighted
Depth (ft)
= 300
Qr(cfs)
= 4054
Area (sqft)
= 17400
Velocity (fUs)
= 233
Wetted Perim (ft)
= 6542
Cnt Depth, Yc (ft)
= 095
Top Width (ft)
= 6400
EGL (ft) o
= 308
Depth (ft)
4 00
300
200
1 00
M
-1 00
Reach (ft)
Y
July 31, 2008
Mark Saunders, President
Ocean Isle Palms, Inc
1321 Ocean Blvd West
Holden Beach, NC 28462
Subject Request for Additional Information
Stormwater Project No SW8 060338 Mod
Ocean Isle Palms Phase 1
Brunswick County
Dear Mr Saunders
Michael F Easley Governor
William G Ross Jr Secretary
North Carolina Department of Environment and Natural Resources
Coleen H Sullins Director
Division of Water Quality
The Wilmington Regional Office received an incomplete Plan Revision regarding the State
Stormwater Management Permit for Ocean Isle Palms on April 30, 2008 The cover letter
indicated that the proposed plan revision is to remove the previously permitted clay liners for
the ponds On May 8, 2008, the Division sent an email to your consultant indicating that the
Plan Revision was incomplete and could not be accepted for review The email requested that
the pond's temporary storage volume be verified due to the permanent pool elevation being
located so far below the seasonal high water table On June 5, 2008, a single plan sheet was
submitted for Pond #12, with a revised SHWT As of this date, the plan revision to remove the
clay liners is still not complete and cannot be accepted for review until the following information
is submitted
Please advise as to the status of construction on these ponds Have the ponds
already been constructed? Were they constructed with or without the approved
and permitted clay liners? If they have been constructed without the permitted
clay liner, you will most likely be required to monitor the ponds in lieu of
enforcement action
Please demonstrate that sufficient storage has been provided for the required
design storm Locating the permanent pool elevation so far into the water table
will most likely result in a higher pool elevation, meaning that necessary storage
space for the design storm is being taken up by the permanent pool
Groundwater modeling to quantify the expected volume of incoming groundwater
based on soil type and transmissibility is an option
3 Please demonstrate that the outlet ditches that the pond discharges into are free
flowing under expected high water conditions With the permanent pool elevation
so far down into the water table, it is imperative that the outlets function
effectively under high water conditions in order for the pond to drawdown to the
design permanent pool elevation within the required 2-5 days and to have the
required storage volume available for the next storm
Please note that this request for additional information is in response to a preliminary review of
the incomplete plan revision request The requested information should be received in this
Office prior to August 31, 2008
N�am�`nCazohna
�vaturally
North Carolina Division of Water Quality 127 Cardinal Drive Extension Wilmington NC 28405 Phone (910) 796 7215 Customer Service
Wilmington Regional Office Internet w iv ncivaterauality ore Fax (910) 350 2004 1 877 623-6748
An Equal Opportunity/Affirmative Acton Employer— 50%Recycledll0%Post Consumer Paper
Mr Saunders
July 31, 2008
Stormwater Application No SW8 060338
If you need additional time to submit the information, please mail, email or fax your
request for a time extension to the Division at the address and fax number at the bottom
of this letter The request must indicate the date by which you expect to submit the
required information The Division is allowed 90 days from the receipt of a completed
application to issue the permit
The construction of any impervious surfaces, other than a construction entrance under
an approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215 1 and
is subject to enforcement action pursuant to NCGS 143-215 6A
Please reference the State assigned protect number on all correspondence Any
original documents that need to be revised have been sent to the engineer or agent All
original documents must be returned or new originals must be provided Copies are not
acceptable If you have any questions concerning this matter please feel free to call me
at (910) 796-7215 or email me at Imda lewis@ncmad net
Sincerely,
Linda Lewis
Environmental Engineer III
ENB/arl S\WQS\STORMWATER\ADDINFO\2008\060338 ju108
CC John Sims, Cape Fear Engineering
Robert Patterson, DWQ
Linda Lewis
Page 2 of 2
CAPE FEAR
Engineering, Inc.
151 P0018 floetl Sm1e 100
BeNdle NC 28451
TEL (910) 38& 1044
FAX (910) 383 1M
www capefearenglneering com
To
NCDENR DWQ
State Stormwater Section
127 Cardinal Drive Ext
Wilmington, NC 28405
-TRT7
Linda Lewis
Transmittal
Date June 5, 2008
File 809-02 "36"
Subject Ocean Isle Palms Phase 1
SW8 060338
❑ As Requested ❑ For Your Files ❑ For Distribution ® For your Review / Action / Approval
❑ Sent via Mail ❑ Sent via Courier
Quantity I Drawing No
1
Revised Plan Sheet (C-13)
REMARKS Revised SHWT Elevation for Pond #12
CC File Copy
Description
Cape Fear Engineering, Inc
��✓�/ p Signed
61?00 � John W Sims IV
Received By
/Date
Transmittal -State SW -clay liner doc
Ocean Isle Palms SW8 060338 Mod
Subject Ocean Isle Palms SW8 060338 Mod
From Linda Lewis <Iinda lewis@ncmail net>
Date Fn, 09 May 2008 13 30 55 -0400
To John Sims <John suns@capefearengmeering com>
John
The Division received an incomplete modified stormwater permit application on April
30, 2008 The application cannot be accepted for review until the following
information is provided
1 To avoid dewatering a site and to guarantee that sufficient volume is available
in the pond, the Permanent pool elevation for a wet pond should be set within 6" of
the SHWT If it is not, then the temporary pool elevation should be calculated
using the approximate SHWT as the baseline for measuring the depth of the temporary
pool volume
Linda
1 of 1 5/9/2008 1 31 PM
CAPE FEAR
Engineering, Inc.
151 Poole Hoed Suite 100
BeNdle NC23451
TEL (810) 38S 1044
FAX (910) 383 1045
www cape(earengmeenng com
To
NCDENR DWQ
State Stormwater Section
127 Cardinal Drive Ext
Wilmington, NC 28405
Attn
Linda Lewis
Transmittal
File 809-02 "36"
Subject Ocean Isle Palms Phase 1
SW8 060338
❑ As Requested ❑ For Your Files ❑ For Distribution ® For your Review / Action / Approval
❑ Sent via Mail ❑ Sent via Courier
Quantity I Drawing No
Description
1 Cover Letter
1 Copy of Ocean Ridge Justification
1 Revised Plan Sheets (1A C-13, 1 B SW-3)
113R I/_T 5
CC File Copy
Lndtal-State SW —clay finer doc
Cape Fear Engineering, IInccmay
Signed u 4""6 , 0j
John W Sims, IV
Received By
Date
4FCAPE FEAR
Engineering, Inc.
April 30, 2006
Linda LeWis
Environmental Engineer
NCDENR-DWQ
Wilmington, NC 28405
KE Ocean Isle Palms — Phase I A f, I B
5W8 000335 — v✓ It 1 7,9 G, le -
Plan Revision — Wet Ponds
Linda
RECEIVED
APR 3 0 2008
BY. ,
Please find attached for your review and approval a plan revision for the above described plan Please
accept this cover letter as the required narrative to describe the proposed revision
The intention of this plan revision is to delete all required clay hners from the approved pond details
for this project Included with this submittal are updated detail sheets with revised pond sections
Engineering Justification for removing the hners was submitted with the plan revisions for Ocean Ridge
Phase 6, 5ection I � 3 Although the Justification specifically addressed Ocean Ridge Phase 6 the
most conservative assumptions were used and apply to the majority if not all Brunswick County Sites
In this case the permanent pool of pond # 12 15 set 4 1 7' below 5HWr and the permanent pool of
pond #2 I is set 3 08 below 51iWT Ponds # 12 and #2 1 both are not adjacent to any wetlands
I trust this information to be sufficient for your review and approval Should you have any questions
comments, or require additional information regarding this matter, please contact this office
5incerely,
John W 51m5, IV
Cc file (820-02 36 )
L\ 151 Poole Road, 5mte 100 • Oelvdle NC2B451 • TEL (910)383-1044 • FAX (910)383-1045
l wwwcapefearengmeermg com
,�
''j
CAPE FEAR
Engineering, Inc.
151 Poole Road Suite 100
eeNAle NC 28451
TEL (910) 383-1044
FAX (910f 3BX1045
www capefearengmeenng tom
To
NCDENR Division of Water Quality
Surface Water Protection Section -SW
127 Cardinal Drive Extension
Wilmington, NC 28405
Attn
IZC'F
E][V�� 1 4 2008
Transmittal
14, 2008
File 809-02 "36"
Subject Ocean Isle Palms Phase 1
Stormwater Name Change
Brunswick County
❑ As Requested ❑ For Your Files ❑ For Distribution ® For your Review / Action / Approval
❑ Sent via Mail ® Sent via Courier
Quantity
Drawing No
Description
1
Cover Letter
1
Original Permit Name/Ownership Change Form
1
Copy of State Stormwater Permit
1
Copy Certification of Conversion
1
Copy Limited Liability Company Annual Report
1
Copy Articles of Organization Including Articles of Conversion
REMARKS If you have questions or comment please contact me at 910 383 1044
CC File
File
Cape Fear Engineering, Inc
r/ i
Signed
Mendith B Butler
Received By
Date
Transmittal -Poole Rd
d�FCAPE FEAR
Engineering, Inc.
August 11, 2008
NCDENR Division of Water Quality
Surface Water Protection Section- Stormwater
127 Cardinal Drive Extension
Wilmington, NC 28405
Subject Ocean Isle Palms Phase 1 Name Change
To Whom It May Concern
We are submitting Ocean Isle Palms Phase 1 name change on behalf of Ocean Isle Palms,
LLC The company has not changed ownership Ocean Isle Palms, Inc have Just changed
the name to Ocean Isle Palms, LLC
fhis phase is still under construction and upon completion the stormwater treatment
system certification will be sent to your office
Sincerely,
Meridith B Butler,
Permit Coordinator
151 Poole Road Suite 100 • 6elville NL28451 • TEL (910)363-1044 • FAX (910)363-1045
wwwcapefearengineering com
p¢vsary�
� r
LIMITED LIABILITY COMPANY
ANNUAL REPORT
NAML OF LIMI I LD LIABILI I Y COMPANY Ocean Isle Palms ll C
SI CRF rARY OF STATF 1 I C ID NUMBFR 0817314
NATURI OF RININFSS Real Estate
REGISFEREDAGEN'F Saunders Mark I
REGIS FIRED OFFICE MAILING ADDRESS 131 Ocean Blvd West
Holden Beach NC 28462
F Filed Annual Report
-1 0 8704679
For leer 2008
Do not data entu manually
S IAIEOF INCORPORAIION N(
REGIS I ERED OFFICE STREET ADDRESS 131 Ocean Blvd Nest
/lolden Beach N( 28462 Braun wick Countv
PRINCIPAL OFFICI TELLPIIONE NUMBER (910) 842-4939
PRINCIPAL OFFICE MAILING ADDRESS 13/ Ocean Blvd (Vest
Holden Beach NC 28462
PRINCIPAI OFFICF SI REET ADDRESS 131 Ocean Blvd West
Holden Beach tbC 28462
MANAGER S/MEM13LIZ S/ORGAN1LLRS
Ncone Mark Saunders
line Member
Addre s s
131 Ocean Blvd W
Holden Beach bC 28462
Nannc Donald Honarth
Title Manager
4ddress
131 Ocean Blvd W
Holden Beach NC 28462
Name Carroll M Lrpscombe
line Manager
4ddress
131 Ocean Blvd W
Holden Beach 1vC 28462
Name Sheldon Tucker
l the Manager
Address
131 Ocean Blvd W
Holden Beach NC 28462
CFRI Il ICATION OF ANNUAL RLPORT MUSI BE COMPLETED BY Al I LIMITED I IABILITY COMPANIES
Muk Saundin
I ORM MUST BE SIGNED BY A MANAGERIMEMBER
Mark Saunders
04/15/2008
DA rE
Member
TYPE OR PRINT NAME TYPE OR PRINT TITLE
ANNIJAI RF POR I FFF S200 MAII 10 ti.n ry of Male Corporation, Division Post Office Box 29525 Raleigh NC 27626 0325
March 10, 2008
Linda Lewis
Environmental Engineer
NCDENR-D WQ
Wilmington, NC 28405
RE Ocean Ridge Phase 6 Section 1 and Section 3
SW8 070917
Plan Revision — Wet Ponds
Linda
Please find attached for your review and approval a plan revision for the above described
plan Please accept this cover letter as the required narrative to describe the proposed
revision
The intention of this plan revision is to delete all required clay liners from the approved
pond details for this project Included with this submittal is the engineering justification
for deleting the clay liners and updated detail sheets with revised pond sections
Pond #5 of this project has been constructed to substantial completion Due to
unforeseen conditions in the field, the orifice and therefore the permanent pool elevation
of the pond were revised by 0 2 feet (from 40 0 to 40 2) to maintain positive drainage
This field change has a negligible impact to the permanent pool area, temporary pool
volume, and temporary pool drawdown The revised detail for Pond #5 is included with
this submittal, and shows the revised permanent pool elevation
Finally, the designers certification for the construction of Pond #5, certified to be in
accordance with the revised plan, is included with this submittal
I trust this information to be sufficient for your review and approval Should you have
any questions, comments, or require additional information regarding this matter, please
contact this office
Sincerely,
K Davis Fennell, PE
cc file (810-0611 36")
4
Stormwater Design Narrative and Calculations '
for
Ocean Ridge Plantation
-Phase 6-
Wet Detention Basins
in
Seasonal High Water Table
Prepared for
Coastal Communities at Ocean Ridge Plantation
351 Ocean Ridge Parkway SW
Ocean Isle Beach, North Carolina 28469
(910) 287-1903
Brunswick County, North Carolina
Date February, 2008
Prepared by
Cape Fear Engineering, Inc.
151 Poole Road, Suite 100
Belville, NC 28451
(910)383-1044
BACKGROUND
Wet detention basins have been widely utilized in eastern North Carolina as a means of providing
treatment for storm water runoff from impervious surfaces The wet detention basin is described
by the 2007 NCDENR Stormwater BMP Manual as a device that will work well in areas with a
shallow water table and poorly drained soils Also from the 2007 NCDENR Stormwater BMP
Manual, "In wet detention basins, a permanent pool of standing water is maintained by the riser —
the elevated outlet of the wet detention basin " (NCDENR Stormwater BMP Manual, revised
09-28-07, page 10-3)
It is generally accepted that siting a wet detention basin in close proximity to wetland areas
requires careful study and planning to prevent any adverse hydrologic impacts (dewatenng) of
the wetland by the pond It is clear that absent any naturally occurring geology, wet detention
basins designed with outlets lower than the wetland elevation may alter wetland hydrology
The Ellipse equation is commonly used to evaluate the impact of a drainage feature, such as a
pond, ditch, or pipe dram, on the hydrology of adjacent wetlands The Ellipse equation makes
the basic assumption that dewatenng will occur due to the drainage feature, and uses that
assumption to approximate how long the dewatenng will take and the horizontal distance over
which the water table is lowered An excerpt from the USDA/NRCS Part 650 Engineering Field
Handbook (Hydrology Tools for Wetland Determination) is attached for reference to the Ellipse
equation and its application to drainage features
It has been suggested that the Ellipse equation be used to prove that wet detention basins will in
fact lower the water table, and to prove that the seasonal high water table will not compromise
the storage volume of the temporary pool Because the first assumption of the Ellipse equation is
that groundwater will be lowered, this creates a circular argument that cannot be solved
Accepting the assumption that ground water will be lowered, the Ellipse equation can be used to
approximate the horizontal impact to the water table over a fixed period of time
The ellipse equation is written as
S = 4K * (m2 +2am)
9
where S = dram spacing or horizontal impact distance (ft)
K = hydraulic conductivity (in/hr)
m= vertical distance, after drawdown, of water table above dram (ft)
a= depth of barrier layer below drains (ft)
q = drainage rate (in/hr)
The drainage rate (q) is written as
v
9=-
where q= drainage rate (in/hr)
v = drainage porosity (F,ft/fr)) * drawdown depth (c, FT)
t = drawdown time
Some of the parameters in the ellipse equation require site specific field study to be properly
determined For example, to measure the depth of the barrier layer, the hydraulic conductivity,
and drainage porosity of the soils at a specific location would require the installation of wells,
pump testing and monitonng for analysis For the purposes of this report, conservative estimates
of these factors are used to generate the closest possible drain spacing
By analyzing the Ellipse equation and performing trials, it is apparent that calculated dram
spacing is impacted by parameter as follows
When K decreases, drain spacing decreases
When in decreases, drain spacing decreases
When v increases, q increases, and therefore dram spacing decreases
Based on this analysis, assumed values for hydraulic conductivity (K) should be estimated low,
the depth to the barrier layer (m) estimated low, and the drainage porosity of the sods (v) should
be estimated high to predict the closest possible dram spacing For the purpose of this report, the
drawdown time will be held constant at 60 days
The first assumption in this analysis is that the seasonal high water table elevation is the design
elevation for the existing saturated surface This assumption is extremely conservative in that the
seasonal high water table occurs for less than 2 months of the calendar year , and during the rest
of a calendar year the water table is significantly lower
The soils at Ocean Ridge Phase 6 are a mix of Leon, Murville, and Torhunta among others The
hydraulic conductivity of these soils ranges from 2-20 inches per hour as reported in the USDA
Soil Survey A hydraulic conductivity of 2 inches per hour (48 inches per day) is assumed for
step 2 of the Ellipse equation below
The drainage porosity (F, also known as available water capacity) for these soils range from 0 05
to 0 30 in/in (or f /ft) A drainage porosity of 0 30 fr/ft is assumed for this report step 3 of the
Ellipse equation below
The depth to the confining layer in the surficial aquifers of Brunswick County ranges from 0 to
50 feet The depth to the confining layer is assumed to be 5 feet for step 5 of the Ellipse equation
below
At Ocean Ridge Phase 6, the greatest proposed change to the water table occurs at Pond # 4,
where the pond bank is at elevation 42, seasonal high water table is at elevation 40 90, and the
proposed normal pool of the pond is at elevation 35 0, so for step 1 of the Ellipse equation
d = 42-35 = 7 feet
c=42-409= I I feet
Applying the Ellipse equation per the example 19-4 of the attached report, along with the
assumption of parameters described above, yields the following
STEP m=d—c=7-11=59feet
STEP 2 K = 2 in/hr = 48 in/day = 4 ft/day
STEP 3 v = F * c, where F = 0 30 ft/ft and c = 1 1 feet
v = 0 30*1 1= 0 33 ft
STEP 4 q = v/t where v is calculated, t assumed to be 60 days
q = 0 33 ft/60 days = 0 0055 ft/day
STEP 5
S = 4K* (mz +tam)
4
where K=4 ft/d
m=59ft
a = 5 ft (assumed)
q = 0 0055 ft/d
S = 522 feet
Given the assumed parameters, the distance between multiple drains is calculated to be 522 feet
As this report addresses a wet detention basin as a boundary condition (only 1 dram), the
horizontal impact to the water table is one half the value, or 261 feet In other words, over a
period of 60 days, the limits of the lowered water table would extend at least 261 feet from the
dram
CONCLUSIONS
For proper application of the Ellipse equation, the assumption that the water table will equalize
to the outlet elevation of the riser must be accepted The riser has the ability to discharge water
24 hours a day, 7 days a week, 365 days a year There is no source of water recharge to a pond
with the ability to overcome this discharge — the flow out of a properly operating riser structure
will always be greater than the flow into the pond, therefore the outlet elevation of the riser will
control the water table and will establish the post -construction modified seasonal high water
table elevation
The design decision to base the normal pool elevation of a wet detention basin on seasonal high
water table elevations is extremely conservative, and perhaps misapplied If the permanent pool
elevation of the basin is set to equal the seasonal high water table elevation, then the basin will
only perform as intended for less than 60 days of the year During the balance of the year, when
the water table is below seasonal high, it is possible that the normal pool elevation could be
controlled by the water table If this occurs, the permanent pool will be held at an elevation
lower than the design depth, the average depth of the pond will be compromised, and
functionality of the shelf vegetated with wetland species will be impaired A better solution to
this design issue is to design the permanent pool of the pond at an average water table elevation
Finally, a clay liner does not prevent the equalization of the basin permanent pool in the water
table, it simply extends the process Even with a clay liner, the permanent pool of the basin and
the water table will equalize, it will simply take more time Given that the elevations will
equalize, it would be better to encourage rather than inhibit the process
illllli111i111illllllllll111llllll111 B2?33 P1014I�So4- 19004
Brunswick County, NC Register of Deeds page 1 of 1
Presenter Ret -7
Taal �_ Rev int
Ck S i( (�_ Ck # Cash $
Cash $ _ Rnanca
G ita nn. 9f docdment are illegible due to conditoo
clori, ial
P current contains seals vended by anginal
^enMatcannot to reproduced or copied
North Carolina Department of The Secretary of State
CERTIFICATION OF CONVERSION
I, ELAINE F MARSHALL, Secretary of State of the State ofNorth Carolina, do hereby certify that
on the 12th day of December, 2007, Articles of Organization Including Articles of Conversion was filed in this
office
CONVERTING
OCEAN ISLE PALMS, INC NC
INTO
OCEAN ISLE PALMS, LLC NC
a limited lability company duly formed under the laws of the State of North Carolina with its period of
duration being Perpetual
The name of the resulting entity was changed by virtue of said conversion to N/A
The effective date of said conversion, if different from the date of filing was N/A
The resulting entity has not filed articles of dissolution and continues to be in existence in this State as
of the date of this certificate
1 FURTHER certify that this certificate is in compliance with North Carolina General Statutes §47-
18 1 and §5513-26 and may be recorded in the office of the Register of Deeds in the same manner as deeds, the
name of the resulting entity appearing in the "Grantee" index
Certification# 87544635-1 Reference# 6990401-es Page 1 of I
Verify this certificate online at w secretary state ne us/venfication
IN WITNESS WHEREOF, I have hereunto set
my hand and affixed my official seal at the City
of Raleigh, this 22nd day of January, 2008
Secretary of State
Y
C200734500170
State of North Carolina
Department of the Secretary of State
ARTICLES OF ORGANIZATION
INCLUDING ARTICLES OF CONVERSION
SOSID 0817314
Date Filed 12/12/2007 10 10 00 AM
Elaine F Marshall
North Carolina Secretar) of State
C200734500170
Pursuant to §§ 57C-2-21, 57C-9A-01 and 57C-9A-03 of the General Statutes of North Carolina,
the undersigned converting business entity does hereby submit these Articles of Organization
including Articles of Conversion for the purpose of forming a limited Lability company
The name of the limited Lability company is Ocean Isle Palms, LLC
The limited liability company is being fonned pursuant to a conversion of another
business entity
The name of the converting business entity is Ocean Isle Palms, Inc and the organization
and internal affairs of the converting business entity are governed by the laws of the state
or country of North Carolina A plan of conversion has been approved by the
converting business entity as required by law
The converting business entity is a (check one) ® domestic corporation, ❑foreign
corporation, ❑ foreign limited liability company, ❑ domestic limited partnership,
❑ foreign limited partnership, ❑ domestic registered limited liability partnership,
❑ foreign limited liability partnership, or ❑ other partnership as defined in G S 59-36,
whether or not formed under the laws of North Carolina
If the limited liability company is to dissolve by a specific date, the latest date on which
the limited liability company is to dissolve (If no date for dissolution is specified, there
shall be no limit on the duration of the limited liability company )
The name and address of each person executing these articles of organization is as
follows (State whether each person is executing these articles of organization in the
capacity of a member organizer or both)
Paul M Hattenhauer, Organizer
4401 Barclay Downs Drive, Suite 200
Charlotte, NC 28209
The street address and county of the initial registered office of the limited liability
company is
Number and Street 131 Ocean Boulevard West
City, State, Zip Code Holden Beach, NC 28462 County Brunswick
CORPORATIONS DIVISION P O BOX 29622 RALEIGH, NC 27626-0622
(Revised January 2002) (Form L-01A)
C200734500170
The mailing address, if different from the street address, of the initial registered office is
The name of the initial registered agent is Mark A Saunders
Principal office information (Select either a orb)
® The limited liability company has a principal office
The street address and county of the principal office of the limited liability company is
Number and Street 131 Ocean Boulevard West
City, State, Zip Code Holden Beach, NC 28462 County Brunswick
• The mailing address, if different from the street address, of the principal office of the
limited liability company is
b ❑ The limited liability company does not have a principal office
10 Check one of the following
❑ (i) Member -managed LLC all members by virtue of their status as members shall
be managers of this limited liability company
® (11) Manager -managed LLC except as provided by N C G S Section 57C-3-20(a),
the members of this limited liability company shall not be managers by virtue of their
status as members
11 Any other provisions which the limited liability company elects to include are attached
12 These articles will be effective upon filing, unless a date and/or time is specified
This is the 6th day of December, 2007
Paul M Hattenhauer, Organizer
Type or Print Name and Title
30103-4 297775
NOTES
1 Fling fee is S125 This document must be filed wtIh the Secretary of State
CORPORATIONS DIVISION P O BOX 29622 RALEIGH, NC 27626-0622
(Revised January 2002) (Form L-0IA)