SW8980434_HISTORICAL FILE_20040624

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO
SW8 q B oi 3y
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
Lp HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
20o%A Q�2DVA
YYYYMMDD
i

O
June 24, 2004
Michael F Easley Governor
William G Ross Jr Secretary
North Carolina Department of Environment and Natural Resources
Alan W Klimek P E ,Director
Division of Water Quality
Coleen H Sullins Deputy Director
Division of Water Quality
Mr Kent Mitchell, President
Bald Head Island Limited
PO Box 3069
Bald Head Island, NC 28461
Subject Permit No SW8 980434MOD
Row Boat Row Subdivision
High Density Subdivision Stormwater Project
Brunswick County
Dear Mr Mitchell
The Wilmington Regional Office received a complete modified Stormwater Management
Permit Application for Row Boat Row Subdivision on April 7, 2004 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
modified Permit No SW8 980434, dated June 24, 2004, for the construction of the
subject project
This permit shall be effective from the date of issuance until April 7, 2010, (the original
expiration date) 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 c'
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 adjudicatory hearing upon written request within sixty (60)
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
If you have any questions, or need additional information concerning this matter, please
contact Linda Lewis, or me at [phone]
Sincerely,
l�-.� �� ✓lam-C��.�,��
Rick Shiver
Water Quality Regional Supervisor
RSS/ arl S \WQS\STORMWAT\PERMIT\980434 jun04
cc Jeff Petroff, P E , Cape Fear Engineering
Delaney Aycock, Brunswick County Inspections
Linda Lewis
Wilmington Regional Office
Central Files
N C Division of Water Quality 127 Cardinal Drive Extension [phone]
Wilmington Regional Office Wilmington NC 28405 [phone] Fax
Customer Service
1 800 623 7748
N DENR

State Stormwater Management Systems
Permit No SW8 980434MOD
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF WATER QUALITY
STATE STORMWATER MANAGEMENT PERMIT
HIGH DENSITY 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
Kent Mitchell, Bald Head Island Limited
Row Boat Row Subdivision
Brunswick County
FOR THE
construction, operation and maintenance of 14 individual infiltration trench systems
and three infiltration basins 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 April 7, 2010 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
2 This stormwater system has been approved for the management of
stormwater runoff as described on pages 3 thru 6 of this permit, the Project
Data Sheets The supdivision is permitted for 18 lots, each allowed a
maximum of 2,500 ft of built -upon area, per Exhibit A attached to this permit
The common area is limited to a maximum of 500 ftZ
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 A
permit modification must be submitted and approved prior to the construction
of additional built -upon area from outside of the approved drainage area
Page 2 of 9

State Stormwater Management Systems
Permit No SW8 980434MOD
5 The following design criteria have been approved and must be maintained in
the permitted infiltration trenches
Drainage Basin #1
a
Drainage Area, acres
1 15
Onsite, ft2
50,094
Offsite, ft2
0
b
Design Storm
1"
c
Total Impervious Surfaces, ft2
25,478
d
Trench Dimensions, L, ft
IT-1 = 37 5, IT-4 & IT-5 = 38 5,
(14 trenches, IT-1 thru IT-14)
IT-2, IT-3, and IT-6 thru IT-14 = 31 5
Width, W, ft
IT-1 thru IT-14 = 2 5'
Height, H, ft
IT-1 thru IT-14 = 2 5'
e
Pipe Diameter & Length
2 50' / 461' total
f
Required Storage Volume, ft3
2,120
g
Provided Storage Volume, ft3
2,263
h
Bottom Elevation, FMSL
40
1
Top of Storage Elevation, FMSL
650
1
Controlling Orifice
18" cp overflow (invert 7 50 FMSL)
k
Type of Soil
Sand, Newhan & Fripp
I
Expected Infiltration Rate
30 0 inches per hour
m
Seasonal High Water Table
2 0 FMSL
n
Time to Draw Down
<1 0 hour
o
Name of Receiving Stream
Bald Head Island Marina
p
Stream Index Number
CPF18-88-8-5
q Classification of Water Body "SC"
Page 3 of 9

State Stormwater Management Systems
Permit No SW8 980434MOD
6 The following design criteria have been approved and must be maintained in
the
permitted infiltration basins
DB #2 DB#3
DB#4
a
Drainage Area, ft2
39,640 30,492
28,314
Onsite, ft2
39,640 30,492
28,314
Offsite, ft2
0 0
0
b
Design Storm
1 5" 1 5"
1 5'
c
Total Impervious Surfaces, ft2
13,890 19,900
9,800
d
Bottom Surface Area, ft2
1,250 1,200
800
e
Bottom Elevation, FMSL
90 70
75
f
Storage Elevation, FMSL
10 8
85
g
Provided Storage Volume, ft3
2,000 1,920
1,280
h
Type of Sod
Sand, Newhan & Fripp
i
Expected Infiltration Rate
30 0 inches per hour
I
Seasonal High Water Table
2 0 FMSL 2 0 FMSL
2 0 FMSL
k
Time to Draw Down, hours
1 0 1 0
1 0
1
Name of Receiving Stream
Cape Fear River
m
Stream Index Number
CPF18-(87 5)
n
Classification of Water Body
"SA"
II SCHEDULE OF COMPLIANCE
1 No homeowner/lot owner/developer shall fill in, alter, or pipe any drainage
feature shown on the approved plans
2 The permittee is responsible for verifying that the proposed built -upon area does
not exceed the allowable built -upon area Once the lot transfer is complete, the
built -upon area may not be revised without approval from the Division of Water
Quality, and responsibility for meeting the built -upon area limit is transferred to
the individual property owner
3 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 of the project area
f Filling in, altering, or piping of any vegetative conveyance shown on the
approved plan
Page 4 of 9

State Stormwater Management Systems
Permit No SW8 980434MOD
4 The Director may determine that other revisions to the project should require a
modification to the permit
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 except roads
7 During construction, erosion shall be kept to a minimum and any eroded areas of
the system will be repaired immediately
8 The permittee grants permission to DENR Staff to enter the property for the
purposes of inspecting the project for compliance with the conditions of this
permit
9 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
10 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 this
pond is fountain HP
11 Prior to transfer of ownership, the system must be inspected by DWQ personnel,
and determined to be in compliance with all permit conditions Records of
maintenance activities will be required
12 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
13 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
14 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
Page 5 of 9

State Stormwater Management Systems
Permit No SW8 980434MOD
15 The permittee shall at all times provide the operation and maintenance
necessary to assure the permitted stormwater system functions 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 revegetation 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 outlet structure, orifice device and catch
basins and piping
q Access to the outlet structure must be available at all times
16 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
17 Prior to the sale of any lot, deed restrictions must be recorded limiting the built -
upon area per lot to the amount as shown on Exhibit A The recorded statements
must follow the form
The maximum built -upon area per lot is 2,500 ft2 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, roofed structures, asphalt, concrete, gravel, brick, stone, slate, and
coquina, but does not include raised, open wood decking, or the water
surface of swimming pools
b The covenants pertaining to stormwater regulations may not be changed
or deleted without concurrence of the State
Alteration of the drainage as shown on the approved plan may not take
place without the concurrence of the State
d Lots within CAMA's Area of Environmental Concern may be subject to a
reduction in their allowable built -upon area due to CAMA regulations
e All runoff on the lot must drain into the permitted infiltration systems This
may be accomplished by 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 infiltration areas or street Lots that
naturally dram into the system are not required to provide these additional
measures
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 bear the signature of the Permittee, the deed book number and page,
and the stamp/signature of the Register of Deeds
Page 6 of 9

State Stormwater Management Systems
Permit No SW8 980434MOD
III GENERAL CONDITIONS
This permit is not transferable except after notice to and approval by the Director
In the event there is a desire for the facilities to change ownership, or there is a
name change of the Permittee or facility, a "Name/Ownership Change Form"
must be submitted to the Division of Water Quality accompanied by appropriate
documentation from the parties involved 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 The permittee is responsible for compliance with all
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
3 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
4 In the event that the facilities fad to perform satisfactorily, including the creation
of nuisance conditions, 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
5 The permit may be modified, revoked and reissued or terminated for cause The
filing of a request for a permit modification, revocation and reissuance or
termination does not stay any permit condition
6 Permittee grants permission to staff of the DWQ to access the property for the
purposes of inspecting the stormwater facilities during normal business hours
7 The permittee shall notify the Division of any name, ownership or mailing
address changes within 30 days
Permit issued this the 24t' day of June, 2004
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
Division of Water Quality
By Authority of the Environmental Management Commission
Permit Number SW8 980434MOD
Page 7 of 9

CAPE FEAR
Engineering, Inc.
Apnl 5, 2004
Linda Lewis
NCDENR
Water Quality
127 Cardinal Drive Ext
Wilmington, NC 28403
RECEI`+TED
APR 0 1 2004
BY
RE Row Boat Row at Bald Head Island, SW8 980434 Mod
Dear Ms Lewis,
FL-,CEIVED
APR 2004
BY — _GYI a
In response to your comment letter dated March 2, 2004, please find the following
The BUA information on the application has been revised to show areas in square
feet Also included are calculations demonstrating the smallest trench's ability to
handle the required runoff
2 Kent Mitchell is still associated with Bald Head Island, while Ken Kirkman is not
The supplements that were previously signed by Ken Kirkman are being
resubmitted with signatures from Kent Mitchell Actually, Bruce Marek from
Bald Head Island has already dropped of the original supplements with your
office, therefore only copies are being resubmitted
3 A calculation sheet is included for trench volumes
I trust this information is sufficient for your review and approval If you have any
questions or require additional information, please contact this office Thank you for
your time on this matter
Sincerely,
Jeffrey Petroff, P E
cc Bruce Marek, BHI
File
151 Poole Road Suite 100 • Belville NC 26451 • TEL [phone] • FAX [phone]
wwwcapefearengmeenng com

PROJECT
CLIENT
CALCULATIONS
0
SUBJECT l r?� ✓ r i( L- ,-1 To �o ✓ r.'r Ru ✓er-F
1-1
DATE
PROJ NO 3— -y 7
DESIGNED BY --Y3f
0 Ali'A-< AQe,+ T-.i I Y^Pte4G 1/2,LvNGIF RECEIVED
r APR 0 7 2004
M PL'2 ✓Io�S F.aR- / Plc A, 12L`„'cH
5W,?gYo43¢
i IDe r�LK � -
1,61� sF
VOLu✓ t;
(�,�c dos roods �S�
,17
1M Pl' Vl--1 12,47b I610/7, Gip r� fj� g/p
= o o S - o GG 9 Cho ED
7
�// = 0 S 9'
V.LVML � C'`A ✓f'h LL, J �Il✓) C�4.M✓.ECG /7 /2CI'J
�os-y7)���svS��
(3� cr
a
U '
Vol- (/F Si,.l A1L Erg
31s
A.ti u'T1/I
Vr-✓...e?� L
IrL sS 1
/Sy 6 c F
V O11....4 �/F
JC Ar+�F.at r_
V.L ✓.+P
�-C �'Ts �-r�ri �N l2t �tH
151 Poole Road SulEe 100
8elolle NC2&451
TEL [phone]
FAX [phone]
w capefeamngmeervng com
4�F CAPE FEAR
ng Engineeri, Inc

CALCULATIONS
PROJECT 20. l.� -A r � d
CLIENT
SUBJECT 12e�6 4 Vo
a-T-1
L= 37 s` ✓ems
_T-2, -T r-3 , 1 %-6 Taau 1. T-/'I
'77- C'r 25) Z (31 S
/S'9 6 3 c
ET -y, —7- T -.S
/a—�L l2t icw Vew-e
/12c- F
L-ce✓=-� %¢c�c+Er C. lSY L3 cf = l70/ c F
/ o /✓CE..�csEs I Q5 c F - 3- 79 r
151 Poole Road Suite 100
8elvdle NC2&451
TEL (910) W3 1044
FAX [phone]
w capefearengmeenng com
r-1
DATE
PROJ NO 3 -�
DESIGNED BY �� P
ti �Ny-v-ssu, ,,R
_ SEAL �t -
CAPE FEAR
Engineering, Inc.

* * * COMMUNICATION RESULT REPORT ( MAR 2 2004 12 20PM ) * * *
P 1
FILE MODE
669 MEMORY TX
OPTION
PERSON FOR ERROR
E-3) NOHANG
ANSWEUP RR LINE FAIL
TTI NCDENR WIRO
ADDRESS (GROUP) RESULT PAGE
----
97908583
E-2) BUSY
E-4) NO FACSIMILE CONNECTION
Michael F Easley, Governor
William G Ross Jr Secretary
North Carolina Department of Environment and Natural i esources
j Alan W P ,Director
O .� Divisionsion of of\IVater Quality
Coleen H Sullins, Deputy Director
Division of Water Quality
FAX COVER SHEET
Date, March 2, 2004
To Jeff Petroff, P E
Company Cape Fear Engineering
FAX # [phone]
No of Pages. 1
From Linda Lewis
Water Quality Section - Stormwater
FAX # [phone]
Phone # [phone]
DWQ Stormwater Project Number SW8 980434 Modification
Project Name Row Boat Row BHI
MESSAGE.
Jeff
The Division received a modified Stormwater Management Permit Application on
December 19, 2004 The application is incomplete Please provide the following items
by close of business on Thursday, March 4, 2004, to continue the review
1 Scott Vinson, who is no longer working at this office, did the original review and
permitting I am having a tittle trouble with the way he reviewed the application

Michael F Easley Governor
William G Ross Jr Secretary
North Carolina Department of Environment and Natural Resources
FAX COVER SHEET
Date
March 2, 2004
To
Jeff Petroff, P E
Company
Cape Fear Engineering
FAX #
790-8583
Alan W Klimek P E Director
Division of Water Quality
Coleen H Sullins Deputy Director
Division of Water Quality
No of Pages 1
From Linda Lewis
Water Quality Section - Stormwater
FAX # [phone]
Phone # [phone]
DWQ Stormwater Project Number SW8 980434 Modification
Project Name Row Boat Row BHI
MESSAGE
Jeff
The Division received a modified Stormwater Management Permit Application on
December 19, 2004 The application is incomplete Please provide the following items
by close of business on Thursday, March 4, 2004, to continue the review
1 Scott Vinson, who is no longer working at this office, did the original review and
permitting I am having a little trouble with the way he reviewed the application
and wrote the permit He lumped all 13 trenches in DA-1 together, without
considering that each trench had it's own drainage area I won't ask that you
revise the application to show a single column for each trench drainage area and
provide separate O&M's for each one, but I must at least require that you report
the proposed built -upon areas in square feet on the application, and demonstrate
in the calculations that the smallest trench in DA-1 (31 5 feet) can handle the
runoff from at least '/2 of the proposed lot BUA plus '/z of the street in front of the
lot
2 Is Kent Mitchell still associated with Bald Head Island Limited? I've heard rumors
from CAMA that neither he nor Ken Kirkman is associated with BHI I cannot
accept the previously signed supplement forms if either of these gentlemen is no
longer affiliated with Bald Head Island
3 Please indicate how you concluded that 2,263 cubic feet has been provided in
the 14 trenches for DA-1 The calculations simply say that 2,263 cubic feet is
provided without any indication as to how this number was derived
RSS\arl S\WQS\STORMWAT\ADDINFO\2004\980434 mar04
N C Division of Water Quality 127 Cardinal Drive Extension [phone] Customer service Aoh
Wilmington Regional Office Wilmington NC 28405 [phone] Fax [phone] NCpENMR

\\000\0
CAPE FEAR
Engineering, Inc
151 Poole Read Suite 100
BeMlle NC 28451
TEL [phone]
FAR [phone]
www capefearengmeenng com
To
JNCDENR
127 Cardinal Drive Extension
Wilmington, INC 28405
Attn
Linda Lewis
RECEIVED
DEC 2003
BY
Transmittal
Date 12/18/03
File 300-07
Subject Row Boat Row
ea
/ SW8 980434 Mod
❑ As Requested ❑ For Your Files ❑ For Distribution or your
❑ Sent via Mail ❑ Sent via Courier
/ Approval
Quantity
Drawing No
Description
2
Stormwater Plans
2
Original and Copy of Permit Application
1
Supplement Forms
2
Design Report and Calcs
1
$420 Application Fee
REMARKS If you have any questions or comments please contact this office
CC
File
BHI-Bruce Marek
Signed
Cape Fear Engineering Inc
PE
Transmittal -Poole Rd doc

1 0 }
DESIGN REPORT
FOR
ROW BOAT ROW SUBDIVISION
PREPARED FOR
BALD HEAD ISLAND LIMITED
CA
ReV15ed December 17 2003 ? reQ
s
RECEIVED - �L
028858
DEC 19 2003
DWQ
PROJ #
Cape Fear Engineering
12/17/03
Project Narrative_Hidensity doc
m
CAPE FEAR ENGINEERING, INC
15 1 Poole Road Suite 100
Belville, NC 26451
[phone]

PROJECT NARRATIVE
General
This project is being resubmitted with a small change to lot 2 19 The impervious
allocation has increased from 1000 sf to 2500 sf An additional infiltration
trench IT- 14 was added to handle the additional impervious No modifications
were made to the rest of the project Calculations and supplements
corresponding to this change have been revised to reflect the chancJe the
remaining calculations and supplements are bemg resubmitted unchanged The
existing stormwater Management Permit number for this project Row Boat Row
is #5W6 960434
Storm Water Management
The total area of Row Boat Row Subdivision is approximately 4 9 acres The
proposed impervious built upon area would be 1 44 acres corresponding to an
impervious ratio of 29 4% This project would be considered a high -density
project with deed restrictions limiting the amount of built upon area per lot in
accordance with the schedule shown in Exhibit A The existing soils are Newhan
Fripp fine sands These soils are extremely well drained with an infiltration rate of
approximately 30 mches / hour Storm water runoff will be conveyed to
infiltration basins and underground infiltration trenches using sheetflow The
stormwater control systems will be located in recorded drainage easements No
mpervious surfaces will be allowed in the stormwater control area
The following justification for design pursuant to 5ection III Required Items
Checklist Form 5WU- 103 Rev 3 99 is noted below
Item n ) Due to the extremely high infiltration rate of the Newhan f- Fripp
sands the 25-year design storm event would be contained within the infiltration
basin shown on the plans (see attached calculations) Since the soil
characteristics of the entire area outside the infiltration basin consists of the
same highly permeable sands an overflow vegetated filter does not appear to be
warranted
Item q ) Due to the extremely high infiltration rate of the Newhan � Fripp
sands the 25-year design storm event would be contained within the infiltration
basin shown on the plans Since the soil characteristics of the entire area outside
the infiltration basin consists of the same highly permeable sands a bypass for
Off-line systems does not appear to be warranted In the unlikely event that the
infiltration basin nears capacity the overflow volume would sheetflow to adjacent
permeable sands This is preferred in lieu of concentrating runoff in a by-pass
system
Cape fear Engineering
12/17/03
Project Narranve_Ht_denstty doe

1 11
The following justification for design pursuant to 5ection III Required Items
Checklist Form 5WU-107 Rev 3 99 is noted below
Item t ) The design storm event would be contained within the underground
infiltration trench as shown on the plans (5ee attached calculations) 51nce the
soil characteristics of the entire area outside the infiltration trench consists of
highly permeable sands an overflow vegetated filter does not appear to be
warranted
5edimentation t Erosion Control
This project will disturb 1 7 acres of and 51lt fencing and vegetative swales will
be the primary controls for sedimentation and erosion control The velocities in
the swales are less than I -ft/sec and will not be erosive All areas that will be
disturbed will be grassed or paved according to the schedules on the drawmgs
Bald Head Island Limited will be the financially responsible party for all land
disturbing activities
Cape Fear Engineering
12/ 17/03
Project Narra[rve_Hi_density doc

INFILTRATION TRENCH
Design Calculations for Row Boat Row
Bald Head Island NC
CAPE tFEAR
Englneer, Inc
151 Pool. Road Suite 1lb
BeMlle NC 28451
TEL [phone]
FA (910, 383 045
www Cape�earengmeermg com
BASIN DATA
Prot No 300 07
12/18/03
infiltration basin As
1
Drainage Area Designation =_ 4 Us - F-
Under round Infiltration Trench'Desi n+ r r r .'§ j 4
ti
Receiving stream class rj9MftSGjwaters
nsite Area = rw � 5 acres
Onsite Impervious Area = 058 acres
Offsite Area = 0 00 acres
Offsde Impervious Area = 006
acres
Using the runoff volume calculations per Simple Method as described by Schueler (1987)
where Rv = runoff coefficient = storm runoff (inches) / storm rainfall (inches)
I = Percent Impervious = Impervious portion of the drainage area (acres) / Drainage area (acres)
Rv = 0 05 + 0 009(1)
Rv = 0 05 + 0 009 ' 504 = 0 504 (in/in)
Volume to be controlled from the design storm event
where Design rainfall = 1 (in)
Rv = 0 504 (in/in)
Drainage Area = 1 15 (acres)
Volume required (cf) = rainfall (in) x Rv (in/in) x Drainage Area (acre) x 1/12(feeUmches) x 43560 (sf/acre)
Vreq d = 1 ' 00 504 '' �1 15 ' 1/12 43560 = 2102 cubic feet
Vprov = :14T7r�
d = 2102 cf < 2263 cf Vprov
Determine drawdown time
Compare infiltration system drawdown time to maximum drawdown period of 5 days
where I = infiltration rate of soil (Soil Type = Newhan & Fripp sands) _
A = bottom area of swale = _
Qavail = IA = 30 in/hr 1770 sf 1 fU12 1 hr/3600sec =
T = V req / Q avail 1 hr/ 3600 sec
T = 2102 cf / 1 23 cfs =
(OK- system draws down in less than 5 days)
30 Whir
1770 sf
1 23 cfs
0 48 hours

PIPESTOR
ROW BOAT ROW 12/18/03
DRAINAGE BASIN-1
MASS INFLOW / STORAGE / AND EXFILTRATION FROM INFILTRATION SYSTEM-1
Procedure in Accordance With FHWA TA 80 218 Design Guide Lines
Infiltration Rate Q (cfs)
= K*I*A
Drainage area (Ac)=
1 15
Pipe size (ft) =
25
Storm event =
25
Trench width (ft) =
25
Length of pipe and trench=
461
Pipe area (ft2) =
49
Trench side height (ft) =
25
Stone area (ft2) =
00
A = Area of exfiltration =
1770 ft2
Stone voids 40% (112) =
00
K = Coeff of permeability =
2 1 E 02 cm/sec
Available storage per It =
49
I = Hydraulic gradient =
1 00
Total Available Storage
2262
Q/ = 1 25 cfs
M
INFLOW / EXFILTRATION / STORAGE RATINGS CHART
TIME
(min)
ACCUMULATED
MASS INFLOW
(cubic feet)
EXHLTRATION
VOLUME
(cubic feet)
STORAGE
REQUIREMENTS
(cubic feet)
AVAILABLE
STORAGE
(cubic feet)
STORAGE SURPLUS
(DEFICIT)
(cubic feet)
5
1 088
375
713
2 262
1 549
10
1 898
749
1 149
2 262
1 113
15
2 532
1 124
1 409
2 262
853
20
3 046
1 498
1 548
2 262
714
25
3 474
1 873
1 601
2 262
661
30
3 838
2 247
1 591
2 262
671
40
4 429
2 996
1 432
2 262
829
60
5 274
4 495
779
2 262
1 482
80
5 868
5 993
(125)
2 262
2 387
100
6 320
7 491
(1 171)
2 262
3 433
120
6 682
8 989
(2 307)
2 262
4 569
180
7 467
13 484
(6 017)
2 262
8 279
240
8 007
17 979
(9 972)
2 262
12 234
360
8 753
26 968
(18215).
2 262
20 477
720
10 019
53 936
(43 917)
2 262
46 179
1 440
11 322
107 872
(96 550)
2 262
98 812
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
INSY 1 As 12/18/03

INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
a\` CAPE FEAR
"%> Engineering, Inc
5040 Now Centro Dnve Suite D
Wilmington N C 28403
Voiue (910) 790 85B4
Fax [phone]J
E mad cfe(a>be//south net
BASIN DATA
Pro/ No 300-07
09/18/2000
300_07mfdtration_basm2_REV2700 xls
1 of4
Total Area = 0 91 acres
Total Impervious Area = 0 32 acres
Percent Impervious = Impervious drainage area (acres)/Drainage area (acres) = 352
A) Determine volume to be controlled from storm (1 5 inch event for SA waters, 1 inch event for others)
Using the runoff volume calculations per Simple Method as described by Schueler (1987)
where Rv = runoff coefficient = storm runoff (inches) / storm rainfall (inches)
I = Percent Impervious = Impervious portion of the drainage area (acres) / Drainage area (acres)
Rv = 0 05 + 0 009(I)
Rv = 0 05 + 0 009 . 352 = 0 366 (in/in)
Volume to be controlled from the design storm event
where Design rainfall = 1 5 (in)
Rv = 0 366 (in/in)
Drainage Area = 0 91 (acres)
Volume required (cf) = rainfall (in) x Rv (in/in) x Drainage Area (acre) x 1/12(feet/hnches) x 43560 (sf/acre)
Vreq d = 1 5 ` 0 366 ' 0 91 ' 1 /12 ` 43560 = 1816 cubic feet

INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
CAPE FEAR
°//' Engineering, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E mad cte(q?bellcouth nPt
Determine the volume of the proposed swale
SWALE DATA
Cross sectional Area (A) = bd +HdA2 = 8 00 sf
bottom width (b) = off 5701 ft
depth (d) =P250
ftsideslope (H V) = 1
length of swale (L) =ft
Prol No 300-07
09/18/2000
300_07infiltration_basin2_REV2700 As
2of4
INFILTRATI❑N SWALE
NOT TO SCALE
Volume proposed (cf) = Cross -sectional area (so x length of Swale (ft)
Vprop = 8 sf 250 It = 2000 cubic feet
Compare volume proposed to volume required from the design storm event
= 2000 cf > Vreq d = 1816 cf
(OK proposed swale volume is greater than minimum required volume)

INFILTRATION SWALE - Schueler Method Prol No 300 07
Design Calculations for Row Boat Row, 09/18/2000
Bald Head Island NC 300_07infiltration_basin2_REV2700 As
3of4
<1E,!5 CAPE FEAR
% Engineering, inc
5040 Now Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E mail cfe(ipbellcouth net
B) Check swale infiltration rate for capacity to control the 25 year 24 hour storm event with no discharge
The average weighted coefficient of runoff is determined by
C ave = Sum[CA I / Sum[A]
Description
AREA C
Impervios Area
0 32 3195
Pervious Area
059 0 15
Sum A = 091 Sum CA =
C ave = 0 393 / 091 =
CA
0 304
0 089
0 393
0 431
Determine required discharge from 25 year-24 hour storm event
Q regd = Cave x I x A
Q regd = 0 43 * 0 33 * 091 = 0 13 cfs
where I = intensity for 25 year 24 hour storm event from Chart E 6 = 0 33 in/hr
A = drainage area = = 0 91 acres
Cave = weighted coefficient of runoff = 043
Check available rate of infiltration provided by proposed swale
where I = infiltration rate of soil (Soil Type = Newhan & Fripp sands) = 30 in/hr
A = bottom area of swale = 5 0 ft * 250 ft = 1250 sf
Qavail = IA = 30 in/hr 1250 sf 1 fU12 in * 1 hr/3600sec = 087 cfs
rate of infiltration with runoff rate from the 25 year storm event
= 0 87 cfs > Q reqd = 0 13 cfs
(OK -No Discharge for 25 yr 24 hr storm event)

'INFILTRATION SWALE - Schueler Method Prol No 300-07
Design Calculations for Row Boat Row 09/18/2000
Bald Head Island, NC 300_071nfiltration_basin2_REV2700 As
4of4
CAPE FEAR
Engfneerfng, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Far (910) 790 R58.3
E mad cfe(dbellcouth net
C) Check the 10 year-10 minute storm event to confirm that swale has capacity without flushing system
where I = intensity for 10 year 10 minute storm event from Chart E-6 = 6 3 in/hr
A = drainage area = = 0 91 acres
Cave = weighted coefficient of runoff = 043
Determine discharge rate from 10 year-10 minute storm event
Q10yr= CavexlxA
Q 10-yr = 0 43 * 63 * 091 = 2 47 cfs
Determine discharge volume from 10 year-10 minute storm event
V 10 yr = Q 10 yr * 10 min duration * 60 sec/min = 1484 cf
Check available volume of the proposed infiltration swale
V avail = design volume (from swale data table) = 2000 cf
Compare design volume of infiltration swale to discharge volume from 10 year storm event of 10 minute duration
Vavail = 2000 cfs > V 10-yr = 1484 cfs
(OK-swale has adequate capacity for 10-yr event without flushing)
Compare infiltration system drawdown to maximum drawdown period of d days
T = V regd / Q avail 1 hr/ 3600 sec
T = 1816 cf I 0 87 cfs 1 hr/ 3600 sec = 0 58 hours
(OK system draws down in less than 5 days)

INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
F
CAPE FEAREngfneerfng, Inc
5040 New Centre Drive Suito D
Wilmington N C 28403
Voice [phone]
Fax [phone]J
E mad cfe(q>bellgouth net
BASIN DATA
Prol No 300 07
09/18/2000
300_07infdtration_basin3_REV2700 xis
1 of4
Total Area = 0 70 acres
Total Impervious Area = 0 32 acres
Percent Impervious = Impervious drainage area (acres)/Drainage area (acres) = 457
A) Determine volume to be controlled from storm (1 5 inch event for SA waters, 1 inch event for others)
Using the runoff volume calculations per Simple Method as described by Schueler (1987)
where Rv = runoff coefficient = storm runoff (inches) / storm rainfall (inches)
I = Percent Impervious = Impervious portion of the drainage area (acres) / Drainage area (acres)
Rv=005+0009(I)
Rv = 0 05 + 0 009 ' 457 = 0 461 (in/in)
Volume to be controlled from the design storm event
where Design rainfall = 1 5 (in)
Rv = 0 461 (in/in)
Drainage Area = 0 70 (acres)
Volume required (cf) = rainfall (in) x Rv (in/in) x Drainage Area (acre) x 1/12(feet/inches) x 43560 (sf/acre)
Vreq d = 1 5 ' 0 461 ' 0 7 ' 1/12 ' 43560 = 1759 cubic feet

INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
CAPE FEAR
7/r Engfneerfng, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E marl cte(dbelhouth net
Determine the volume of the proposed Swale
SWALE DATA
Cross -sectional Area (A) = bd +HdA2
= 8 00 sf
bottom width (b)
= 5r0 ft
depth (d)
= 1 ft
sideslope (H V)
= 3 1
length of swale (L)
= 240 ft
EAS-VENT - WIDTH AS INDICAT,D
Prot No 300 07
09/18/2000
300_07infiltration_basin3_REV2700 As
2of4
INFIL T RATICIN SWALE
NOT TO SCALE
Volume proposed (cf) = Cross -sectional area (so x length of swale (ft)
Vprop = 8 sf 240 ft = 1920 cubic feet
(Compare volume proposed to volume required from the design storm event
= 1920 cf > Vreq d = 1759 cf
(OK -proposed swale volume is greater than minimum required volume)

INFILTRATION SWALE - Schueler Method Prol No 300-07
Design Calculations for Row Boat Row 09/18/2000
Bald Head Island NC 300_07infiltration_basin3_REV2700 xis
3of4
\' CAPE FEAR
'/� Engineering, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E mad cfe(q�be/Nouth net
B) Check swale infiltration rate for capacity to control the 25 year-24 hour storm event with no discharge
The average weighted coefficient of runoff is determined by
C ave = Sum[CA ] / Sum[A]
Description AREA C CA
Impervios Area 0 32 0a95 0 304
Pervious Area 038 0 15 0 057
SumA= 07 Sum CA = 0361
Cave = 0361 / 07 = 0516
Determine required discharge from 25 year-24 hour storm event
Q regd = Cave x I x A
Qreqd= 052 ` 033 ` 07
where I = intensity for 25 year-24 hour storm event from Chart E-6
A = drainage area =
Cave = weighted coefficient of runoff
Check available rate of infiltration provided by proposed swale
where I = infiltration rate of soil (Soil Type = Newhan & Fripp sands)
A = bottom area of swale = 5 0 ft ` 240 ft
Qavail = IA = 30 in/hr 1200 sf 1 11/12 in ` 1 hr/3600sec
rate of infiltration with runoff rate from the 25 year storm event
0 83 cfs > Q reqd = 0 12 cfs
(OK No Discharge for 25 yr-24 hr storm event)
= 0 12 cfs
= 0 33 in/hr
0 7 acres
052
30 in/hr
1200 sf
= 0 83 cfs

'INFILTRATION SWALE - Schueler Method Prot No 300 07
Design Calculations for Row Boat Row 09/18/2000
Bald Head Island, NC 300_07infiltration_basin3_REV2700 As
4of4
CAPE FEAR
WE��\NN
``%'
ngineering, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]J
E mail cfe(dbelkoutfr nit
C) Check the 10 year-10 minute storm event to confirm that swale has capacity without flushing system
where I = intensity for 10 year-10 minute storm event from Chart E 6 = 6 3 in/hr
A = drainage area = = 0 7 acres
Cave = weighted coefficient of runoff = 052
Determine discharge rate from 10 year-10 minute storm event
Q 10-yr = Cave x I x A
Q10yr= 052' 63 ' 07 = 227cfs
Determine discharge volume from 10 year-10 minute storm event
V 10-yr = Q 10 yr ' 10 min duration ` 60 sec/min = 1365 cf
Check available volume of the proposed infiltration swale
V avail = design volume (from swale data table) = 1920 cf
Compare design volume of infiltration Swale to discharge volume from 10 year storm event of 10 minute duration
Vavail = 1920 cfs > V 10-yr = 1365 cfs
(OK swale has adequate capacity for 10-yr event without Flushing)
Compare infiltration system drawdown to maximum drawdown period of d days
T = V regd / Q avail 1 hr/ 3600 sec
T = 1759 cf / 0 83 cfs 1 hr/ 3600 sec = 0 59 hours
(OK- system draws down in less than 5 days)

INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
�.
CAPE FEAR
'
Engineering, Inc
5040 New Centro DOVL Suite D
Wilmington N C 28403
Voice [phone]
Fax (910) 790 rt51t,3
E mad cfo(q?bellcouth net
BASIN DATA
Prot No 300 07
09/18/2000
300_07infiltration_basin4_REV2700 As
1 of4
Total Area = 0 65 acres
Total Impervious Area = 0 22 acres
Percent Impervious = Impervious drainage area (acres)/Drainage area (acres) = 338
A) Determine volume to be controlled from storm (1 5 inch event for SA waters, 1 inch event for others)
Using the runoff volume calculations per Simple Method as described by Schueler (1987)
where Rv = runoff coefficient = storm runoff (inches) / storm rainfall (inches)
I = Percent Impervious = Impervious portion of the drainage area (acres) / Drainage area (acres)
Rv = 0 05 + 0 009(I)
Rv = 0 05 + 0 009 " 338 = 0 355 (in/in)
Volume to be controlled from the design storm event
where Design rainfall
Rv
Drainage Area
1 5 (in)
0 355 (in/in)
= 0 65 (acres)
Volume required (cf) = rainfall (in) x Rv (in/in) x Drainage Area (acre) x 1/1 2(feet/inches) x 43560 (sf/acre)
Vreq d = 1 5 ' 0 355 ' 0 65 ' 1/12 ' 43560 = 1255 cubic feet

'INFILTRATION SWALE - Schueler Method
Design Calculations for Row Boat Row
Bald Head Island NC
CAPE FEAR
Engineertng, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E mad cteft�belNouth "Pt
Determine the volume of the proposed swale
SWALE DATA
Cross sectional Area (A) = bd +HdA2
= 8 00 sf
bottom width (b)
= 5 0 ft
depth (d)
= 1 ft
sideslope (H V)
= 3 1
length of swale (L)
= 160 ft
ENT - MOTH AS INDICATED
Prot No 300 07
09/18/2000
300_07infiltration_basin4_REV2700 xls
2of4
INLIL-RATI❑N SWALE
NOT TO SCALE
Volume proposed (cf) = Cross -sectional area (so x length of swale (ft)
Vprop = 8 sf 160 ft =
volume proposed to volume required from the design storm event
1280 cubic feet
1280 cf > Vreq d = 1255 cf
(OK -proposed swale volume Is greater than minimum required volume)

INFILTRATION SWALE - Schueler Method Prot No 300-07
Design Calculations for Row Boat Row 09/18/2000
Bald Head Island, NC 300_07infiltration_basin4_REV2700 xis
3of4
CAPE FEAR
Englneering, Inc
5040 New Centre Drive Suite D
Wilmington N C 28403
Voice [phone]
Fax [phone]
E mail cfe(cpbellcouth net
B) Check swale infiltration rate for capacity to control the 25 year 24 hour storm event with no discharge
The average weighted coefficient of runoff is determined by
C ave = Sum[CA ] / Sum[A]
Description
AREA
C
CA
Impervios Area
072
Or95
0209
Pervious Area
043
O15
0 065
Sum A =
065
Sum CA =
0 274
C ave = 0 274 /
065
=
0 421
Determine required discharge from 25 year-24 hour storm event
Q regd = Cave x I x A
Q regd = 0 42 ` 0 33 ' 065
where I = intensity for 25 year-24 hour storm event from Chart E-6
A = drainage area =
Cave = weighted coefficient of runoff
Check available rate of infiltration provided by proposed swale
where I = infiltration rate of soil (Soil Type = Newhan & Fripp sands)
A = bottom area of swale = 5 0 ft ` 160 ft
Qavail = IA = 30 in/hr 800 sf 1 fU12 in ` 1 hr/3600sec
rate of infiltration with runoff rate from the 25 year storm event
= 0 56 cfs > Q regd = 0 09 cfs
(OK No Discharge for 25 yr 24 hr storm event)
= 0 09 cfs
in/hr
= 0 65 acres
042
= 30 in/hr
800 sf
= 0 56 cfs

INFILTRATION SWALE - Schueler Method Prot No 300-07
Design Calculations for Row Boat Row 09/18/2000
Bald Head Island, NC 300_07infiltration_basin4_REV2700 As
4of4
CAPE FEAR
7Jr Engfneerfng, Inc
5040 New Centre Drive Suite D
Wilmington N C 29403
Voice [phone]
Fax (910) 790 B58,1
E mad cfe(cPbelkouth net
C) Check the 10 year-10 minute storm event to confirm that swale has capacity without flushing system
where I = intensity for 10 year-10 minute storm event from Chart E-6 = 6 3 in/hr
A = drainage area = = 0 65 acres
Cave = weighted coefficient of runoff = 042
Determine discharge rate from 10 year-10 minute storm event
Q10yr= CavexlxA
Q 10 yr = 0 42 ' 63 ' 065 = 1 72 cfs
Determine discharge volume from 10 year 10 minute storm event
V 10-yr = Q 10 yr ' 10 min duration ' 60 sec/min = 1034 cf
Check available volume of the proposed infiltration swale
V avail = design volume (from swale data table) = 1280 cf
Compare design volume of infiltration swale to discharge volume from 10 year storm event of 10 minute duration
Vavail = 1280 cfs > V 10-yr = 1034 cfs
(OK swale has adequate capacity for 10-yr event without flushing)
Compare infiltration system drawdown to maximum drawdown period of d days
T = V regd / Q avail 1 hr/ 3600 sec
T = 1255 cf / 0 56 cfs 1 hr/ 3600 sec = 0 63 hours
(OK- system draws down in less than 5 days)