SW8011121_Historical File_20080530

State Stormwater Management Systems
Permit No. SW8 permit#
•
May 30, 2008 `O`c Ci\O r'* ki`Rd or
Art Ricks, Member Manager
Lena Springs, LLC
1630 Military Cutoff Road
Wilmington, NC 28403
Subject: Stormwater Permit No. SW8 011121 Modification
Lena Springs Subdivision
High Density Subdivision Project
Brunswick County
Dear Mr. Ricks:
The Wilmington Regional Office received a complete Stormwater Management Permit
Application for Lena Springs Subdivision on May 29, 2008. 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 011121, dated May 30, 2008, for the construction of the project, Lena
Springs Subdivision.
This permit shall be effective from the date of issuance until June 17, 2012, 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 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 150B 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 Rhonda Hall, or me at [phone].
Sincerely,
Edward Beck
Regional Supervisor
Surface Water Protection Section
ENB/rbh: S:\WQS\STORMWATER\PERMIT\011121 MOD.may08
cc: Shane Lippard, Right Angle Engineering, PC
Brunswick County Inspections
Jeff Phillips, Brunswick County Engineering
Rhonda Hail
Wilmington Regional Office
Central Files
Page 1 of 9

State Stormwater Management Systems
Permit No. SW8 Dermit#
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
Art Ricks, Lena Springs, LLC
Lena Springs Subdivision
Old Mill Road and Forest Hills Drive, Navassa, Brunswick County
FOR THE
construction, operation and maintenance of a two 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 June 17, 2012 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
runoff as described in I page 3 of this permit. The subdivision is
permitted for 182 lots, each allowed a maximum of 3,000 square feet of built-
upon area. The maximum amount of built-upon area allotted to Nevasa
Community Center lot is 38,099 square feet.
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.
5. The Nevasa Community Center lot must submit a separate Offsite Stormwater
Management Permit application package to the Division of Water Quality and
receive a permit prior to any construction on the lot.
Page 2 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
6. The following design elements have been permitted for this wet detention pond
stormwater facility, and must be provided in the system at all times.
a Drainage Area, acres: total drainage area
Onsite, ft2: onsite drainage area
Offsite, ft2: offsite drainage area
b. Total Impervious Surfaces, ft2: BUA
Lots at bua per lot ft2. lot bua
Roads/Parking, ft2: road bua
Other, ft2: other such as sidewalk, cart path, etc.
Offsite, ft2: offsite bua
c. Pond Depth, feet: pond design depth
d. TSS removal efficiency: 85 or 90%
e. Design Storm: design storm (generally 1")
f. Permanent Pool Elevation, FMSL: PP elevation
g. Permitted Surface Area @PP, ft2: surface area @PP
h. Permitted Storage Volume, ft3: storage volume at temporary pool
i. Storage Elevation, FMSL: storage elevation
j. Controlling Orifice: orifice size"0 pipe
k. Permanent Pool Volume, ft3 PP volume
I. Forebay Volume, ft3: forebay volume
m. Maximum Fountain Horsepower: Fountain HP
n. Receiving Stream / River Basin: stream / river basin
o. Stream Index Number: stream index#
p. Classification of Water Body: "stream class"
II. SCHEDULE OF COMPLIANCE
1. No homeowner/lot owner/developer shall fill in, alter, or pipe any drainage feature
(such as swales) shown on the approved plans as part of the stormwater
management system without submitting a revision to the permit and receiving
approval from the Division.
2. The permittee is responsible for verifying that the proposed built-upon area for
the entire lot does not exceed the maximum allowed by this permit. 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. If an Architectural Review Board or Committee is required to review plans for
compliance with the BUA limit, the plans reviewed must include all proposed
built-upon area. Any approvals given by the Board do not relieve the homeowner
of the responsibility to maintain compliance with the permitted BUA limit.
4. 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.
5. 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.
Page 3 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
6. 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.
7. The Director may determine that other revisions to the project should require a
modification to the permit.
8. 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.
9. During construction, erosion shall be kept to a minimum and any eroded areas of
the system will be repaired immediately.
10. 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.
11. 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.
12. Permanent seeding requirements for the stormwater control must follow the
guidelines established in the North Carolina Erosion and Sediment Control
Planning and Design Manual.
13. 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.
Page 4 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
14. 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.
15. 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.
16. 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 011121, 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 3,000 square feet and the
maximum built-upon area for the Navasa Community Center Lot is 38,099
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. Lots within CAMA's Area of Environmental Concern may be subject to a
reduction in their allowable built-upon area due to CAMA regulations.
h. All runoff on the lot must drain 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.
Built-upon area in excess of the permitted amount will require a permit
modification.
j. The Nevasa Community Center lot must submit a separate Offsite
Stormwater Management Permit application package to the Division of
Water Quality and receive a permit prior to any construction on the lot.
17. 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 ail 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 permit#
18. 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.
19. 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
#1 is 1/2 horsepower. The maximum pump power for a fountain in Pond #2
is 1/3 horsepower
III. GENERAL CONDITIONS
1. 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 fail 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.
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.
Page 6 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
8. The permittee shall notify the Division in writing of any name, ownership or
mailing address changes within 30 days.
9. 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 issued this the 30th day of May, 2008.
NORTH CAROLINA ENVIRONMENTAL MANAGEMENT COMMISSION
for Coleen H. Sullins, Director
Division of Water Quality
By Authority of the Environmental Management Commission
Permit Number SW8 011121
Page 7 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
Lena Springs Subdivision Page 1 of 2
Stormwater Permit No. SW8 011121
Brunswick County
Designer's Certification
, as a duly registered in
the State of North Carolina, having been authorized to observe (periodically/weekly/full
time) the construction of the project,
(Project)
for (Project Owner) hereby state that, to the
best of my abilities, due care and diligence was used in the observation of the project
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:
SEAL
Signature
Registration Number
Date
Page 8 of 9

State Stormwater Management Systems
Permit No. SW8 permit#
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 Building Inspections
Page 9 of 9

IGHT ANGLE
ENGINEERING,PC
212 Princess Street Wilmington,NC 28401 Tel.[phone] Fax[phone]
May 22,2008
Rhonda Hall
Division of Water Quality
NCDENR
127 Cardinal Dr.Ext.,
Wilmington,NC 28405 by Fax [phone] �'� '2 8 ZD
08
Re: Lena Springs Subdivision- SW8 011121
Brunswick County
Ms.Hall,
We are providing revised calculations for the Lena Springs stormwater permit to accommodate
the proposed Navassa Community Center impervious amounts. We have calculated the amount
of runoff based on plans by Sparks Engineering but we have also recommended that the car
parking area be constructed of pervious concrete to reduce the amount of impervious to the pond
which will overall reduce the amount of runoff going to the existing vegetated swales and pond.
Please feel free to contact us at any time if there are questions or we could be of any assistance.
Sincerely,
0
Shan ippard,P.E.
Project Engineer
Right Angle Engineering

Revised Stormwater Calculations
for
LENA SPRINGS ESTATES
Permit Mod. SW8 011121
May 2008
By: RIGHT ANGLE ENGINEERING, P.C.
2 12 Princess Street
Wilmington, North Carolina 28401 <,.
(9 10) 25 I-8544 .4
(9 10) 25 I-2208 (fax) '

•
IMPERVIOUS AREA TOTALS
Total Development
Ir WDB#1-Onsite DB#1-Offsite WDB#2 Total
Pond Drainage Area(acres): 33.16 11.44 14.95 59.55 acres
Built-upon Area(ft2): 599408 135449 314371 1049228 ft2
Built-upon Area(acres): 24.09 acres
Wet Detention Basin#1
On-site
Property Area BUA
Proposed Lots 1385208 112 141 lots© 3000.00 = 423000 ft2
31.8 acres
Roads 6208 LF Road @ 26 = 161408 ft2
w/Sidewalk
5 future lots 59093 ft2 5 lots at 3000.00 = 15000 ft2
Total 1444301 ft2 599408 ft2
33.16 acres 13.76 acres
Off-site
Property Area BUA
Existing Forest Hills Drive 27300 fie(ROW) Road(465' 20')= 9300 ft2
Community Center 161280 ft2 Bldg.&Parking 38099
Fire Dept.Tract(.92 AC) 40000 ft2 (80%)= 32000 1
Residential Lot on Forest Hills(undev.) 43560 ft2 assume 10000 10000
Residential Lot on Forest Hills(dev.) 43560 ft2 4000 sf existing,6000 future 10000 10000
Lots 169050 ft2 *(18 lots©1750 sf)= 31500 ft2
*1750 sf is used because only half of these
lots drains to detention pond
Main Street(1/2 draining to swale#1) 13650 ft2 Road(455'*10')= 4550 f
Total 498400 ft2 135449 f
11A4 acres 3.11 a
Wet Detention Basin#2
On-site
Property Area BUA
Proposed Lots 466092 ft2 36 lots© 3000.00 = 108000 ft2
Roads 1885 LF Road n 26 = 49010 ft2
w/Sidewalk
Commercial(4.25 AC) 185130 ft2 (85%)= 157361 ft2
Total 651222 ft2 314371 ft2
14.95 acres 7.22 acres

Wet Detenslon Basin#1 Design
Drainage Area= 44.f; acres
Impervious Area= 16.L7 acres
Percent Impervious= 37.8%
Pond depth= ft
TSS removal= 'r'l9. SA/DA Interpolation Table
SA/DA= 2 l;7' 5 5 5.5
(No vegetative filter required) 30.00% 2.2 2.2
37.83% 2.67
40.00% 2 : 2.8
Minimum Required Surface Area at Permanent Pool:
= 0.027 • 44.60 43560 51862 sf
Minimum Required Volume(Schueler Method,see calculations):
Rv=0.05+0.009 (37.83) 0.3904
Volume=(1"/12")• 0.390 • 44.60 •43560 63209 ft3
Approx.Permanent Pool Dimensions= 400.0 by 133.3 53333 sf
Actual Surface Area Provided at PP= 538CJ > 51862 © Elev. 1'? ft
Need at Least 63209 ft3 of storage/ 55562 1.14 ft
Therefore,use 1.20 ft
Elevation of Temporary Pool= 12 + 1.20 ft= 13.2 ft
Surface Dims of Temp.Pool= 370 by 125.00
Actual Surface Area at 13.2 = 0 7224 sf
Temporary Storage Volume Provided= 66674 ft3 actual vs.design of: 63209 ft3
Forebay Volume-Minimum 20%of Permanent Pool Volume
Volume by average area= 53800 sf©PP and 10i-•0 SF at bottom
Actual Permanent Pool Volume= 159500 cf
Forebay Volume Required= (.2• 159500 ) 31900 cf
Forebay Depth= 5 ft
Surface Ares at bottom of forebay(Elev.3T)= 3500 sf
Surface Area at top of forebay(Elev.42')= 10000 sf
Forebay Volume Provided= •337f 0 cf
Orifice Sizing
Q2 63209 / 172800 0.366 cfs(Flowrate required for a 2 day drawdown)
Q6= 63209 / 432000 0.146 cfs(Flowrate required for a 5 day drawdown)
a2= 0.10362
a6= 0.041449
Choose a 3"Circular Orifice,Average Head= (1.20-(1/2p'(2in/12)/2= 0.538 ft
dia(in)=3 a=pi(r"2)= 0.0491 sf
Q=Ca(2gh)".5= 0.1733 cfs
0.366 cfs > 0.1733 cfs > 0.146 cfs
Choose a 4"Circular Orifice,Average Head (1.20-(1/2)*(4in/12)/2= 0.517 ft
dia(in)=4 a=pi(M2)= 0.08727 sf
Q=Ca(2gh)".5= 0.30203 cfs
0.366 cfs > 0.3020 cfs > 0.146 cfs
Therefore,use a 4"Orifice

Pre-Development 25 Year Storm by Rational Formula
Q=CIA= impervious= 0.00%
pervious= 100.00%
C= 0.3
I= 7.14 in/hr I(in/hr)=g/(h+T)for T=5 to 120 minutes
Tc= 10.00 min
A= 44.6 ac
Q=CIA= 95.57 cfs
Post-Development 25 Year Storm by Rational Formula
Q=CIA= Cimpervious 0.90
Cpervious= 0.20
Cw= 0.465
= 7.14 I(in/hr)=g/(h+T)for T=5 to 120 minutes
Tc= 10.00
A 44.6
Q=CIA 148.06 cfs
Difference between Pre and Post Development
Q 52.49 cfs
Size Outlet Pipe
D=16(Qn/(s".5))"(3/8)
Qpost= 148.06 cfs
s= 0.50%
n= 0.009
D(theoretical)= 48.1 In
D(actual)= 48.0 in
Size Emergency Spillway
Channel Lining:Rip Rap
n= 0.0::0
1.00ft. 1 S= 1.t
3 Q Mannings(cfs)= 79.63 Max
H 15.0 ftH
Length= 15 ft
Velocity= 4.42 ft/s
Depth with Freeboard= 1.00 ft

Wet Detension Basin#2 Design
Drainage Area 14.95 acres
Impervious Area= 7.22 acres
Percent Impervious= 48.3%
Pond depth 6 ft
TSS removal= 90%
SA/DA= 2.70%
(No vegetative filter required)
Minimum Required Surface Area at Permanent Pool:
0.027 14.95 • 43560 = 17583 of
Minimum Required Volume(Schueler Method,see calculations):
Rv=0.05+0.009 (48.27) = 0,4845
Volume=(1"/12")' 0.484 14.95 "43560= 26291 ft3
Approx.Permanent Pool Dimensions= 233.0 by 77.7 = 18096 sf
Actual Surface Area Provided at PP= 18000 > 17583 @ Elev. 13 ft
Need at Least 26291 ft3 of storage/ 18000 1.46 ft
Therefore,use 1.50 ft
Elevation of Temporary Pool= 13 + 1.50 ft= 14.5 ft
Surface Dims of Temp.Pool= 271 by 90.00
Actual Surface Area at 14.5 = 19000 sf
Temporary Storage Volume Provided= 27750 ft3 actual vs.design of: 26291 ft3
Forebay Volume-Minimum 20%of Permanent Pool Volume
Volume by average area= 18000 sf©PP and 10000 SF at bottom
Actual Permanent Pool Volume= 84000 cf
Forebay Volume Required (.2` 84000 )= 16800 cf
Forebay Depth 5 ft
Surface Area at bottom of forebay(Elev.37')= 2600 sf
Surface Area at top of forebay(Elev.42') 9700 sf
Forebay Volume Provided 30750 cf
Orifice Sizing
Q2= 26291 / 172800 0.152 cfs(Flowrate required for a 2 day drawdown)
Qs= 26291 / 432000 0.061 cfs(Flowrate required for a 5 day drawdown)
a2= 0.03755
as= 0.015018
Choose a 2"Circular Orifice,Average Head= (1.50-(112)(2in/12)/2= 0.708 ft
dia(in)=2 a=pi(r42)= 0.0218 sf
Q=Ca(2gh)^.5= 0.0884 efs
0.152 cfs > 0.0884 cfs > 0.061 cfs
Choose a 3"Circular Orifice,Average Head (1.50-(1/2)141n/12N2= 0.688 ft
dia(in)=3 a=pi(02)= 0.04909 sf
Q=Ca(2gh)^.5= 0.1.9597 cfs
0.152 cfs < 0.1960 cfs > 0.061 cfs
Therefore,use a 2"Orifice

Pre-Development 25 Year Storm by Rational Formula
Q=CIA= impervious 0.00%
pervious= 100.00%
C= 0.2
I= 7.14 in/hr l(in/hr)=g/(h+T)for T=5 to 120 minutes
Tc= 10.00 min
A= 15.0 ac
Q=CIA= 21.36 cfs
Post-Development 25 Year Storm by Rational Formula
Q=CIA= Cimpervious 0.90
Cpervious= 020
Cw= 0.538
I= 7.14 /(in/hr)=g/(h+7)for T=5 to 120 minutes
Tc= 10.00
A= 15.0
Q=CIA= 57.44 cfs
Difference between Pre and Post Development
Q= 36.08 cfs
Size Outlet Pipe
D=16(Qn/(s^.5))^(3/8)
Qpost= 57.44 cfs
s= 1.00%
n= 0.009
D(theoretical)= 29.6 in
D(actual)= 30.0 In
Size Emergency Spillway
Channel Lining: Rip Rap
n= 0.030
\ i 1.00 ft. s= 1.00%
3 Q Mannings(cts)= 79.63 Max
14--- 15.0 ft--►I
Length= 15 ft
Velocity= 4.42 ft/s
Depth with Freeboard= 1.00 ft

Runoff and Pipe Calculations
Lena Springs Estates
Second Pipe Entrance to WDB#1
Post-Development 10 Year Storm
Q=CIA=
C pervious = 0.2
C(weighted)= 0.53 C impervious= 0.9
= 6.30 I(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 10.00 min
A-total = 9.50 ac
A-imp = 4.50 ac
Q = CIA= 31.82
Size Outlet Pipe
D= I6(Qn/(s".5))^(3/8)
s= 0.50%
n = 0.009
D(theoretical)= 27.0 in
D (actual) = 30.0 in
Use 24 inch
Pipe Entrance 1 to WDB#2
Post-Development 10 Year Storm
Q =CIA=
C pervious= 0.2
C(weighted)= 0.67 C impervious= 0.9
I = 6.30 I(in/hr) —g/(h+T)for T=5 to 120 minutes
Tc= 10.00 min
A-total = 12.00 ac
A-imp= 8.00 ac
Q= CIA= 50.40
D= 16(Qn/(0.5))^(3/8)
s= 0.50%
n = 0.009
D(theoretical)= 32.1 in
D(actual) = 36.0 in
Use 36 inch for entrance

Pipe Entrance 2 to WDB#2
Post-Development 10 Year Storm
Q =CIA=
C pervious= 0.2
C(weighted)= 0.48 C impervious= n_s
I = 6.30 /(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 10.00 min
A-total= 5.80 ac
A-imp= 2.30 ac
Q=CIA= 17.45
D = 16(Qn/(0.5))"(3/8)
s= 1.00%
n = 0.013
D (theoretical)= 21.8 in
D (actual)= 24.0 in
Use 24 inch
Pipe From CI#2 to 3
Post-Development 10 Year Storm
Q=CIA=
C pervious= 0.2
C(weighted)= 0.47 C impervious= 0.9
= 7.20 /(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 5.00 min
A-total = 3.40 ac
A-imp= 1.30 ac
Q=CIA= 11.45
Size Outlet Pipe
D= 16(Qn/(s^.5))^(3/8)
s= 0.60%
n = 0.009
D (theoretical)= 17.8 in
D (actual)= 18.0 in
Use 18 inch
Pipe From Ex CI to#6
Post-Development 10 Year Storm
Q =CIA=
C pervious= 0.2
C(weighted)= 0.54 C impervious= 0.9
I = 6.30 /(in/hr) =g/(h+7)for T=5 to 120 minutes
Tc= 10.00 min
A-total= 6.60 ac
A-imp= 3.20 ac
Q=CIA- 22.43

Size Outlet Pipe
D = 16(Qn/(s^.5))^(3/8)
s= 0.50%
n = 0.009
D(theoretical)= 23.7 in
D (actual)= 24.0 in
Use 24 inch
Pipe from CI#10 to CI #11
Post-Development 10 Year Storm
Q=CIA=
C pervious = 0.2
C(weighted)= 0.54 C impervious= 0.9
I = 7.20 /(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 5.00 min
A-total= 6.00 ac
A-imp= 2.95 ac
Q = CIA= 23.51
D = 16(Qn/(s".5))"(3/8)
s= 0.50%
n = 0.009
D (theoretical)= 24.1 in
D (actual)= 24.0 in
Use 36 inch for entrance
Pipe From Cl#7 to 8
Post-Development 10 Year Storm
Q=CIA=
C pervious= 0.2
C(weighted)= 0.55 C impervious= 0.9
I = 7.20 I(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 5.00 min
A-total = 4.00 ac
A-imp = 2.00 ac
Q=CIA= 15.84
Size Outlet Pipe
D = 16(Qn/(0.5))^(3/8)
s= 0.50%
n = 0.009
D (theoretical)= 20.8 in
D(actual)= 24.0 in
Use 24 inch

Pipe from CI #15 to#16
Post-Development 10 Year Storm
Q=CIA=
C pervious= 0.2
C(weighted)= 0.56 C impervious= 0.9
I = 7.20 1(in/hr) =g/(h+T)for T=5 to 120 minutes
Tc= 5.00 min
A-total = 2.50 ac
A-imp = 1.30 ac
Q=CIA= 10.15
D = 16(Qn/(s".5))^(3/8)
s= 0.50%
n = 0.009
D (theoretical)= 17.6 in
D (actual)= 18.0 in
Use 18 inch
Pipe from CB 2 to CI#20
Post-Development 10 Year Storm
Q=CIA=
C pervious= 0.2
C(weighted)= 0.86 C impervious= 0.9
I = 7.20 I(in/hr) =g/(h+T for T=5 to 120 minutes
Tc= 5.00 min
A-total = 7.60 ac
A-imp= 7.12 ac
Q=CIA= 46.83
D= 16(Qn/(s".5))^(3/8)
s= 0.50%
n = 0.009
D (theoretical)= 31.2 in
D (actual)= 36.0 in
Use 36 inch for entrance

Temporary Sediment Erosion Control
Lena Springs Subdivision
Sediment Basin Sizing -Wet Detention Basin #1
Disturbed Drainage Area = 20.00 acres (70'wide clearing limits along roadways)
Impervious Area = 2.00 acres during construction, 20 acre maximum
Percent Impervious = 10.0%
Storage of Sediment Calculation
V= 1800 CF per Acre
V= 36000 CF required
During Construction Q=CIA= for 10 yr Storm
C pervious= 0.2
C(weighted)= 0.23 C exposed earth= 0.5
I = 7.20 I (in/hr)=g/(h+T)for T=5 to 120 minutes
Tc= 5
A= 20.00
Q=CIA= 33.12 cfs
Calculate Surface Area Required for Erosion Control
Qpeak= 33.1 cfs
SA= (0.01)*Qpeak
SA= 14427 SF of trap area for efficiency
For 1 trap = 14427 SF per trap
36000 CF per trap volume
Actual size provided= 57324 SF
Design Depth to be= 6 FT
Actual Volume Provided = 159500 CF
Sediment Basin Sizing -Wet Detention Basin #2
Disturbed Drainage Area = 14.95 acres (70'wide clearing limits along roadways)
Impervious Area to dam = 2.00 acres during construction, 15 acre maximum
Percent Impervious = 13.4%
Storage of Sediment Calculation
V= 1800 CF per Acre
V= 26910 CF required
Q=CIA= for 10 yr Storm
C pervious= 0.2
C(weighted)= 0.24 C exposed earth- 0.5
I = 6.30 I (in/hr)=g/(h+T)for T=5 to 120 minutes
Tc= 10
A= 14.95
Q=CIA= 22.62 cfs

Calculate Surface Area Required for Erosion Control
Qpeak= 22.6 cfs
SA= (0.01)*Qpeak
SA= 9852 SF of trap area for efficiency
For 1 traps= 9852 SF per trap
26910 CF per trap volume
Actual size provided= 18000 SF
Design Depth to be= 6 FT
Actual Volume Provided = 84000 CF
Temporary Rock
Check Dam Sizing
Size all for worst case
Drainage Area to dam = 3.00 acres
Impervious Area to dam = 0.00 acres 52272 SF
Percent Impervious= 0.0%
Storage of Sediment Calculation
V= 1800 CF per Acre
therefore 5400 CF required
Assume cleaned twice during project concurrence
provide 2700 CF storage
2700 CF per trap volume required
Assume depth to provide storage = 5 FT
Trap to be 15 FT wide to fit normal ditch width.
Trap Storage Length = 80 FT of excavated storage
Trap Volume Provided = 3000 CF -- more than required

Disturbed Area Calculation
8093 LF Roads
80 Feet Wide Disturbance
647440 SF
14.86 AC
Pond Area Disturbance
61000 SF WDB #1
37000 SF WDB#2
98000 SF
2.25 AC
17.5 AC for Lot Clearing adjacent to RAM's
34.61 AC Total Disturbance

Outlet Protection Sizing
Q (flowrate) Depth (ft) Do (in) La(ft) W(ft) 3*Do(ft)
Outlet Protection -Out 156.00 1 48 35 39.00 12.0
of Detention Pond 1
Outlet Protection -Out 76.00 1 36 25 28.00 9.0
of Detention Pond 2
3*Do
W=Do+ La
Do
La ►

� P. 1
* * * COMMUNICATION RESULT REPORT ( NOV. 7.2006 1:33PM )
TTI NCDENR WIRO
FILE MODE OPTION ADDRESS (GROUP) RESULT PAGE
291 MEMORY TX 92512208 OK P. 8/8
REASON FOR ERROR
E-1) HANG UP OR LINE FAIL E-2) BUSY
E-3) NO ANSWER E-4) NO FACSIMILE CONNECTION
0"V+IAT.4, Michael F. Easley, Governor
William G. Ross,Jr.,Secretary
North Carolina Department of Environment and Natural Resources
5 Alan W. Klimek, P.E. Director
Division of Water Quality
FAX COVER SHEET
Date: November 7, 2006 No. of Pages: 8
To: Shane Lippard From: Rhonda Hall
Company: Right Angle Eng. Water Quality Section Stormwater
FAQ: 251-2208 Fax#: [phone]
Phone#: [phone]
DWQ Stormwater Project Number: SW8 011121 Modification
Project Name: Lena Springs Subdivision
MESSAGE:
Shane:
The Wilmington Regional Office received a Stormwater Management Permit Application for
I pna Snrinna Si ihtliviaim tin AA int i f 151 9nnA nraliminan/ r'rainaiu of that infnrmofinn i,ae

A7 Michael F. Easley, Governor
QG William G. Ross, Jr., Secretary
�t r North Carolina Department of Environment and Natural Resources
Q `C Alan W. Klimek, P.E. Director
Division of Water Quality
FAX COVER SHEET
Date: November 7, 2006 No. of Pages: 8
To: Shane Lippard From: Rhonda Hall
Company: Right Angle Eng. Water Quality Section Stormwater
FAX: [phone] Fax#: [phone]
Phone#: [phone]
DWQ Stormwater Project Number: SW8 011121 Modification
Project Name: Lena Springs Subdivision
MESSAGE:
Shane:
The Wilmington Regional Office received a Stormwater Management Permit Application for
Lena Springs Subdivision on August 18, 2006. A preliminary review of that information has
determined that the application is not complete. The following information is needed to
continued the stormwater review:
1. Please provide a note on the plans that all roof drainage must be directed so as to be
picked up by the pond, and the runoff from all impervious surfaces must be directed to
the forebay.
2. Please either delineate all wetlands on site, disturbed or undisturbed, or note on the
plans that none exist.
3. Please provide deed restrictions for the single family lots. For your convenience, I have
enclosed:
(a) a copy of the draft deed restriction that were submitted with the original
application
(b) Form "A" — Deed Restrictions High Density Residential Subdivision (Example
language)
(c) Form "B" - Deed Restrictions High Density Residential Subdivision (This form
can be notarized and submitted as proposed deed restrictions. The recorded
deed restrictions will still need to be submitted at a later date.)
North Carolina Division of Water Quality 127 Cardinal Drive Extension Phone[phone] Customer Service1-877-623-6748 ne
Wilmington Regional Office Wilmington,NC 28405-3845 FAX [phone] Internet h2o.enr.state.nc.us r'? Caron�a
Ytuurae/
An Equal Opportunity/Affirmative Action Employer—50%Recycled/10%Post Consumer Paper

Page 2 of 2
Lena Springs Subdivision
SW8 011121 Modification
4. Please verify that there are 186 single family lots associated with this site. I can only
account for 182 lots.
5. Please verify the lot numbers on the plan. There appears to be two lots that are
numbered 167 and no lot numbered 166.
ENB1rbh: S:IWQS\STORMWATIADDlNFO120061011121 Mod.nov06

DESIGN NARRATIVE FOR HIGH DENSITY TREATMENT OF STORMWATER
AT LENA SPRINGS SUBDIVISION
OLD MILL ROAD AND FOREST HILLS DR.
BRUNSWICK CO., N.C.
August, 2006
TABLE OF CONTENTS
1.0 PROJECT DESCRIPTION
2.0 SITE DESCRIPTION
3.0 ADJACENT PROPERTY
4.0 DRAINAGE CONSIDERATIONS
5.0 EROSION CONTROL CONSIDERATIONS .. � '.
• �:;` w Via .
6.0 CONSTRUCTION SCHEDULE
7.0 VEGETATION PLAN SEAL
7023917 4
8.0 MAINI aNANCE PLAN
APPENDIX 'g���
IMPERVIOUS AREA TOTALS
STORM PIPING CALCULATIONS
DETENTION POND SIZING CALCULATIONS
Lena Springs Subdivision
August,2006

1. Project Description: The Lena Springs Subdivision project is an expansion of a
previously permitted project that was named Town of Navassa Affordable Housing
Project and had a Stormwater Permit Number SW8 011121. This project design will
expand the existing subdivision to add more lots and provide commercial area fronting
Old Mill Road. The existing Wet Detention Basin be expanded and a second Wet
Detention Basin will be constructed. The land disturbing activity associated with the
project will consist of clearing and grubbing of trees, clearing existing drainage swales,
grading of the site, and sediment and erosion control measures such as a silt fence,
gravel construction entrance, and a sediment basin. Further into construction, the
sediment basin will be converted to an onsite detention pond. Also included in the
project will be storm piping, water lines, and sewer lines, and paved roads with curb and
gutter. The total area which will be disturbed for this project is 17.1 acres.
2. Site Description: The project site is in Brunswick Co., NC, located directly to
the south of where Old Mill Road intersects with Main Street. The property on which the
development will take place is currently owned by The General Baptist State Convention
of North Carolina, Inc. (GBSC).
On site soils consist mainly of Baymeade, Blanton, Goldsboro, Mandarin, and Norfolk
soils. These soils are mainly loamy, fine sands.
There are no existing wetlands onsite.
New construction onsite will consist ot paved roads with curb and gutter, curb inlets,
storm piping, and a detention pond. Also included will be a gravity sewer collection
system and a water distribution system.
General slope of the site from north to south towards the back of the site.
Land use in the vicinity is residential.
3. Adjacent Property: The areas adjacent to the project site are mostly
residential areas.
4. Drainage Considerations: Drainage calculations to determine the size ot storm
piping is attached in the appendix — Storm Piping Calculations. The project site is
graded so that stormwater drains into strategically placed curb inlets and existing
swales. From the curb inlets, storm water will empty into a network of storm pipes which
drain into onsite stormwater detention ponds. Wet Detention Basin #1 will be expanded
to accommodate additional runoff and Wet Detention Basin #2 will be constructed to
handle the remainder of the site. The storm pipe network empties into the detention
ponds below the permanent pool elevation. Existing swales also drain into the pipe
drainage network which empties into the detention pond.
Calculations showing the sizing of the stormwater detention pond are shown in the
attached appendix — Detention Pond Sizing Calculations. The ponds are designed to
receive a Total Suspended Solids (TSS) removal of 90%. With 90% TSS there is no
need for a vegetative filter. The required temporary storage volume was determined
using the Schueler Method and basing calculations on a 1" rainfall event. Then the
permanent pool volume is determined based on the permanent pool surface area and
the depth of the pool. Then 20% of that volume is to be used for the forebay volume.
Lena Springs Subdivision
August,2006

Next the orifice was sized to keep the drainage time of the 1 inch storm event between 2
and 5 days. A principal spillway was designed to drain stormwater that rises above the
temporary pool elevation. It was sized using the excess runoff created from pre and
post development for the 25 year storm. An emergency drainage spillway was sized to
handle the same flow as the principal spillway, and will be one foot above the temporary
pool elevation.
In addition, a bypass swale will be constructed at the north end of the site. The swale
will serve the function of draining runoff from outside the project boundary and emptying
it into the existing creek to the east of the site.
5. Erosion Control Considerations: The following erosion control measures are
used on this project:
1. Temporary Gravel Construction Entrance/Exit
To prevent sediment from leaving the site, temporary gravel construction entrances
should be installed where Forest Hills Drive enters the site and where Church
Street enters the site. For dimensions and specifications, see construction details.
2. Land Grading
The existing slope of the site is from north to south towards the back of the lot.
Most of the disturbed areas on the site will drain into curb inlets which will empty
into stormwater piping and drain into an onsite detention pond.
3. Silt Fence
Silt fence should be installed prior to clearing and gradi6'g activities. Silt fence
should be checked routinely. If needed, silt fence should be cleaned and replaced
if damaged. See Construction Detail for dimensions and specifications.
4. Inlet Protection
Inlet protection consisting of a small portion of silt fence surrounding proposed curb
inlets will be utilized to prevent sediment from entering the drainage system. See
Construction Detail for dimensions and specifications.
5. Detention Pond
A detention pond will be built to control sediment from leaving the site. It will be
constructed at the south end of the lot. See Construction. Detail for dimensions
and specifications.
6. Construction Schedule:
1. Obtain plan approval and other applicable permits.
2. Hold pre-construction meeting at least one week prior to beginning construction.
3. Install temporary construction entrance/exits.
4. Before clearing and grading of the site, install silt fencing and clean and replace as
necessary.
5. Build onsite detention pond.
Lena Springs Subdivision
August,2006

6. Check existing swales and clear as necessary.
7. Begin clearing and grading of the site.
8. Construct onsite curb inlets with inlet protection.
9. Install storm piping.
10. Install sewer and waterlines and pave new roadway.
11.All erosion and sediment control practices will be inspected bi-weekly and after each
rainfall event. Needed repairs will be made immediately.
12.After the entire covered area is stabilized, all temporary measures will be removed.
and permanent vegetative repairs to be completed.
7. Vegetation Plan:
1. After complete stabilization of the entire covered area, top cover soils will be
roughened by making 1"-2" deep grooves perpendicular to the slope.
2. Spread lime (agricultural limestone) evenly over the area at a rate of 1.5 tons/acre;
spread 10-10-10 fertilizer at a rate of 1000 lb/acre and incorporate into the top 6" of
soil.
3. Loosen surface prior to applying seed.
4. Broadcast seed at recommended rates.
5. Rake seed into the soil and lightly pack to establish good contact.
6. Mulch with 4000 lb/acre grain straw or equivalent and anchor by weighted farm disc
set nearly straight or other mulch anchoring tool.
7. Mow as needed and refertilize in late winter or early spring by topdressing with 10-
10-10 fertilizer.
8. Graded surfaces shall not be exposed without grass coverage for more than 15
days. If grades are not complete and exposure is more than 15 days, temporary
seed with rye grain at 50 lb/acre.
8. Maintenance Plan:
1. Contractor shall maintain all sedimentation and erosion control devices during
construction.
2. All devices shall be checked after each rain event and weekly. Repairs shall be
made immediately when detected.
3. Any deficiencies shall be brought to the immediate attention of the Engineer.
Lena Springs Subdivision
August,2006

Seed Types and Application Rate/Schedule
Temporary Seeding
Grass Type Amount/ 1000 SF Time of Seeding Initial
Rye Grain 1-2 lbs Nov. —Jan. 25 lbs 10-10-10
Brown Top Mullet 1-2 lbs June—Aug. 25 lbs 10-10-10
Permanent Seeding
Grass Type Amount Time of Initial Fertilization/ Fertilization/ Fertilization /
/1000 Seeding 1000 sf 1000 sf 1000 sf
sf Maintenance maintenance maintenance
Burmuda, 1-2 lbs Apr. — 25 lbs March-April Each 4-8 Aug.-Sept.
Common June 10-10-10 12 lbs Weeks 12Ibs
10-10-10 1-2 lbs N. 10-10-10 _
Fescue, Tall 5-7 lbs Sept. — 25 lbs Feb-March May & Dec. Sept.-Oct.
(Kentucky Oct. 10-10-10 12 lbs %to 1 lb. n. 12 lbs
31) Feb. — 10-10-10 10-10-10
Oct.
Sericea 1-2 lbs March— 25 lbs Feb-March %2 to 1 lb. N. N/A
Lespedeza Apr. 10-10-10
(Slopes)
END OF PLAN
Lena Springs Subdivision
August,2006

IGHT ANGLE
ENGINEERING,PC
212 Princess Street Wilmington,NC 28401 Tel.[phone] Fax[phone]
August 9,2006 O
\A6
Linda Lewis,PE 1�\
Division of Water Quality
NCDENR U POA
127 Cardinal Dr. Ext.,
Wilmington,NC 28405 by Fax [phone] 2
Re: Lena Springs Subdivision 0
Brunswick County
Ms. Lewis,
Enclosed is a modification permit for the above referenced project. The existing pond is
proposed to be expanded and a second pond to be added to treat the stormwater for the proposed
subdivision.
We are providing two sets of permit application,calculations, and plans for your review. Please
feel free to contact us at any time if there are questions or we could be of any assistance.
Sincerel ,
Shane Lippard,P.E.
Project Engineer
Right Angle Engineering
AUG 1 4 2006