SW6120706_HISTORICAL FILE_20120804

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW (dZ,�i
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
HISTORICAL FILE
DOC DATE
YYYYMMDD

I
Mason&Hanger
it I ).rV�i = %i rrrrnrntt�unt (. innl��n+V.
August 13, 2012
Mr. Brian Lowther
Wetlands and Stormwater Branch
North Carolina Department of Environmental Protection
512 N. Salisbury Street
Raleigh, NC 27604
Re: Stormwater Project No. SW6120706
SOF Training Facility (Pope)
Cumberland County
Dear Mr. Lowther
D
AUG .1 4 ZOfz
DENR - WATER c'u;;LliY
I appreciate your taking the time to speak with my associate, Mike Mayer, concerning the additional information
you requested for the stormwater permitting for this project. Enclosed please find the revised plan sheets, as
well as the revised pages of the report which address the necessary changes and the revised supplemental
worksheet. Here is a brief summary of the changes/additional information requested:
1) As discussed with Mr. Mayer, the seasonal high water table (SHWT) was estimated using the
information provided by the Savannah Army Corps of Engineers geotechnical investigation. The SHWT is
estimated to be below the permanent pool (PP) elevation, and exceeding the 6" tolerance. Therefore, a
geocomposite clay liner is being required in both the forebay and the basin at all elevations below the PP
elevation. The estimated SHWT elevation, how it was assumed as well as the lining requirement have been
noted on the plan set (sheet CG504) and in the Stormwater Management Report. In addition, the SHWT
shown in the supplement has been coordinated with the plan set.
2) The flow path through the forebays has been checked. The shape of the northern most forebay has
been revised, as well as the conveyance ditch leading to this forebay. The ditch has been gradually widened to
slow down the flow of water to the forebay. Additional rip -rap lining has been added at the entrance to the
forebay to further reduce the flow rate and aid in TSS removal. Minor landscaping adjustments have also been
made at the vegetative shelf to account for the grade change.
3) The outlet detail on sheet CG500 has been removed, as well as the second outlet detail on sheet
CG504. The only outlet detail shown is for the used outlet structure.
4) As discussed with Mr. Mayer, as the project is on a military installation, there is no public right of way
associated with the site. In addition, no drainage easements will be able to be granted.
Again, thank you for your assistance with this project. If you need any additional information or clarification,
please do not hesitate to contact me.
Very truly yours,
(ZIV4��
Don Higgins, PE
Civil Engineer
Day & Zimmermann
Enclosures
The Mason & Hanger Group Inc. 300 West Vine Street, Suite 1300 Lexington, KY 40507 t 859.252.9980 f 859.253.0781 masonandhanger.com
Day & Zimmermann. 125 the Parkway, Suite 400 Greenville, NC 29615 t 864.241.6768 f 864.241.6750 dayzim.com

lc L-�u4AJ -Lo kv ,"p-4- ?A-J�I 12sa,J .
/ Application Completeness Review
5� First Submittal ❑ Re -submittal Date Received: Date Reviewed: By Bill Diuguid
' DevelopmentlProject Name: SO F
Receiving stream name Li L 0wR­C z-i r-rLE vification: C
F
river Basin: CAPS F�Enk!
For post -construction requirements, a program will be deemed compliant for the areas where it is
implementing any of the following programs: WS-1, WS-II, WS-III, WS-IV, HOW, ORW, Neuse River Basin
NSW, Tar -Pamlico River Basin NSW, and the Randleman Lake Water Supply Watershed Nutrient
Management Strategy.
High Density Projects that require a 401/404 within an NSW require 85% TSS, 30% TN and 30% TP removal.
T&E Species (Goose Creek, Waxhaw Creek or Six Mile Creek Water Sheds): Al
Latitude and Long itude:35-3o " Al -7? at 9?1 W Jurisdiction Ft. axkG G I Cans tAAlu
Project Address: 070 -' 570Jt !r ir¢ C-T �Gouu7
Engineer name and firm: To L :a_ Al A-Vo
Phone: ail:
Is the project confirmed to be in the State MSI Stormwater Permit jurisdiction? U -Yes or ❑ No
❑ Low Density (no curb and gutter) ❑ Low Density with curb and gutter outlets U'I-ligh Density ❑ Other
.— 401/404 impacts to surface waters, wetlands, and buffers (add language to cover letter and/or add info letter)
�;&-'BUA 36 • 9):
sa' Check for $505.00 included
rf Original signature (not photocopy) on application
m"' Legal signature (Corporation-VP/higher, Partnership -General Partner/higher, LLC-member/manager, Agent).
Check spelling, capitalization, punctuation: htip://www.secretary.state.nc,us/corporations/tliepage,aspx
If an agent signs the application, a signed letter of authorization from the applicant must be provided which
includes the name, title, mailing address and phone number of the person signing the letter,
❑ For subdivided projects, a signed an notarized deed restriction statement
❑ Sealed, signed & dated calculations(A/0-r- SEA-t.0� Se-e- r)A-Ai_r - ��fr�i 1'r -tit.2 #• ox`�
V Correct supplement and O&M provided for each 13;'on site (check all that were provided & number of each)
❑ Bioretention
❑ Dry Detention Basin
❑ Filter Strip
❑ Grass Swale
❑ Infiltration Basin
❑ Infiltration Trench
❑ Level Spreader
❑ Permeable Pavement
❑ Restored Riparian Buffer
❑ Rooftop Runoff Management
❑ Sand Filter
❑ Stormwater Wetland
Filet Detention Basin
❑ Low Density
❑ Curb Outlet
❑ Off -Site
❑ NCDOT Linear Road
�arrative
wo sets of sealed, signed & dated layout & finish grading plans with appropriate details
Description of stormwater management provided
Soils report provided -/- Cr-15s 7 K ck
W1A -tt-, Wetlands delineated or a note on the plans or in the accompanying documents that none exist on site and/or
adjacent property Cyco-d • VA -tar- 3 ' 4o t,f' AoL.ct/
G. tails for the roads, parking area, cul-de-sac radii, sidewalk widths, curb and gutter;
imensions & slopes provided
Drainage areas delineated ElPervious and impervious reported for each ❑ Areas of high density
rBMP operation and maintenan a reements provided
p n c lete' pplication Incomplete Returned: (Date)
�ExG2rr Fors I$�` a' c,-LG.'
Comments ��M KF- x s�i obe��0 +p r►� 5JZtJ1
r� /
May 5, 2011 Revision, Bill Diuguid

r
r
.' .� ..

WDENR
North Carolina Department of Environment and Natural Resources
Reverly Eaves Perdue
vovernor
Mr. Don Higgins, PE
Mason & Hanger
300 West Vine St., Ste. 1300
Lexington, KY 40507-181.4
Division of Water Quality
Charles Wakild, RE,
Director
May 24, 2012
Subject: Stormwater Permit Application Return
SOF Training Facility (Pope)
Application Return #1284
Cumberland County
Dear Mr. Higgins:
Dee Freeman
Seueiary
The Division of Water Quality received your Stormwater Management Permit Application for the subject
project on May 22, 2012. After a preliminary review the submittal/design was found to be substantially
incomplete, and we are returning the submittal application and application fee to you.
The application is incomplete based'mainly on the following items:
1. Calculations must be sealed, signed, and dated.
2. The information is not consistent between SWU-101, supplement form, calculations, and plans. This
includes, but is not limited to, volumes, areas, elevations, dimensions, etc.
3. The supplement forms are merely a tool for summarizing final design results. Please`provide
supporting calculations for the wet pond. This includes treatment volume calculations using the
simple method, provided volume, drawdown, low Flow orifice sizing, average depth, etc.
4. A soils report must be provided that states what the SHWT elevation is based on borings) within the
footprint of the proposed wet pond. The seasonal high water table is usually detected by the mottling
of the soil that results from mineral leaching. The SHWT elevations were left blank on the supplement
forms, and must be completed.
5. Any offsite areas not bypassed must be accounted for in the BMP design.
6. A cross-section of the wet pond must be provided that shows slopes, elevations, ect.
7. Many of the MDE's in chapter 10 of the BMP Manual are not being met. Please revise the pond to meet
all required elements.
Wetlands and Stormwater Branch
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Location:512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone]
Internet: www.ncwaterquality.org
An Equal Opportunity 4 Affirmative Action Employer
One
NorthCarolina
Naturally

Mr. Don Higgins, P.E.
Page 2 of 2
May 24, 2012
8. Wet ponds designed for 85% TSS removal must discharge to a properly designed (see chapter 8) level
spreader and 30' Filter strip. To waive this requirement, the pond could be designed for 90% TSS
removal.
9. A hardened emergency spillway trust be provided for the wet Bond.
10. The proposed pond must have a forebay and a 10' wide vegetated shelf at a 10:1 slope. A planting plan
for the vegetated shelf must also be provided on the plans.
11. There is no low flow orifice provided. The orifice should slowly release the 1" design storm volume
over a 2-5 day period.
12. The piedmont/mountain SA/DA tables may be used for this project location. The coastal tables are
only for the 20 coastal counties.
Please see the design checklist on our website and on the Forms to help check that your re -submittal
includes all necessary items. It can be downloaded from
http://portal.ncdenr.org/web/wq/ws/su/statesw/forms-docs#tab-3. In addition, please be sure the
wet detention pond design meets all the requirements in the rules and BMP Manual,
http://portal.ncdenr.org/web/wq/ws/su/bmp-ch10. The rules can be found at
http://portal.ncdenr.org/web/wq/ws/su/statesw/rules-laws.
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.
If you have any questions concerning this matter, please contact me at [phone], or
[e-mail].
Sincerely,
Robert D. Patterson, PE
Stormwater Permitting Unit
cc: David Heins - Fort Bragg DPW
'SPU files
ec: Lee Ward - Fort Bragg DPW/WMB
Mike Lawyer - Fayetteville Regional Office
Don Higgins, PE - Mason & Hanger
David Heins -- Fort Bragg DPW

NCDENR
North Carolina Department of Environment and
Division of Water Quality
Beverly Eaves Perdue Charles Wakild, P.E.
Governor Director
August 3, 2012
Mr. Don Higgins
Day Et Zimmerman
125 The Parkway, Suite 400
Greenville, NC 29615
Natural Resources
Subject: Request for Additional Information
Stormwater Project No. SW6120706
SOF Training Facility (Pope)
Cumberland County
Dear Mr. Higgins:
Dee Freeman
Secretary
The Division of Water Quality Central Office received a request to modify the Stormwater Management Permit for the subject
project on July 27, 2012. A preliminary review of that information has determined that the application is not complete. The
following information is needed to continue the stormwater review:
1. The permanent pool (PP) elevation should be within 6 inches of the seasonal high water table (SHWT). The supplement
indicates the PP is lower than SHWT while the plans indicate the PP is able the SHWT. Please revise the design and fix
any inconsistencies. Also, I could not locate the SHWT in the soils report.
2. The length of the flowpath to width ratio needs to be at least 3:1 in make sure the stormwater is not short circuited
through the basin. The second forebay looks to not be providing the 3:1 flowpath. Please make sure both forebays are
providing the 3:1 ftowpath.
3. A few inconsistencies were noted on the plansheets. The outlet detail on CG500 does not match the details on CG504.
Also, the details on CG504 should match. One is missing the orifice and the trash guards are different. Please revise the
details to be accurate.
4. Please show proposed drainage easements and public right of way on the plans.
The requested information should be received by this Office prior to August 17, 2012, or the application will be returned as
incomplete. The return of a project will necessitate resubmittat of atl required items, including the application fee. If you
need additional time to submit the information, please send your request, including date by which you expect to submit the
required information, to my attention. The Division is allowed 90 days from the receipt of a completed application to
issue the permit.
Please reference the State assigned project number on all correspondence. New original documents must be provided and
copies are not acceptable. If you have any questions concerning this matter feet free to contact me at [phone] or
brian. [e-mail].
Sincerely,
Brian Lowther
Environmental Engineer
cc: Fayetteville Regional Office
Stormwater Permitting Unit Files
ec: David Heins, Environmental Division Chief (DPW)
Wetlands and Stormwater Branch One
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 NorthCarolina
Location: 512 N. Salisbury St. Rategh, North Carolina 27604 �aturaCC�
Phone: [phone] FAX: 919-807-i494
Intemet: www.ncwatemuality.org

Application Completeness Review
First Submittal ❑ Re -submittal Date Received: Date Reviewed: 8 l
Development/Project Name: SD a
Receiving stream name G,` C)Cla si ' atiol
fiver Basin: C'4 D.". F�
Z By Bill Diuguid
For post-constructioh requirements, a program will be deemed compliant for the areas where it is
implementing any of the following programs: WS-I, WS-II, WS-III, WS-IV, HQW, ORW, Neuse River Basin
NSW, Tar -Pamlico River Basin NSW, and the Randleman Lake Water Supply Watershed Nutrient
Management Strategy.
High Density Projects that require a 401/404 within an NSW require 85% TSS, 30% TN and 30% TP removal.
T&E Species (Goose Creek, Waxhaw Creek or Six Mile Creek Water Sheds):
Latitude and Longitude: 35 30 4'5t4l- — 2? OI 91 W Jurisdiction f_C'A__t,8A4 31
Project Address: s Cv�
Engineer name and irm: peol
Phone: �'6*— Z4-z d28 8, ' s co
Is the project confirmed to be in the State MSI Stormwater rmit jurisdictio ? es or f 3 No
❑ Low Density (no curb and gutter) ❑ Low Density with curb and gutter outlets 111-19igh Density ❑ Other
❑ 401/404 impacts to surface waters, wetlands, and buffers (add language to cover letter and/or add info letter)
6KBUA
Vpram heck for $505.00 included
�riginal signature (not photocopy) on application
egal.signature (Corporation-VP/higher, Partnership -General Partner/higher, LLC-memberlmanager, Agent).
Check spelling, capitalization, punctuation: http://www.secretary.state.nc.us/corporations/thepage.aspx
If an agent signs the application, a signed letter of authorization from the applicant must be provided which
includes the name, title, mailing address and phone number of the person signing the letter.
�or subdivided projects, a signed and notarized deed restriction statement
Baled, signed & dated calculations
iZ Correct supplement and O&M provided for each BMP on site (check all that were provided & number of each)
❑ Bioretention
❑ Dry Detention Basin
❑ Filter Strip
❑ Grass Swale
❑ Infiltration Basin
❑ Infiltration Trench
o Level Spreader
❑ Permeable Pavement
❑ Restored Riparian Buffer
❑ Rooftop Runoff Management
❑ Sand Filter
❑ Stormwater Wetland
EKVet Detention Basin
❑ Low Density
❑ Curb Outlet
❑ Off -Site
❑ NCDOT Linear Road
8/3 o sets of sealed, signed & dated layout & finish grading plans with appropriate details
ae arrative Description of stormwater management provided
ils report provided
: Wetlands delineated or a note on the plans or in the accompanying documents that none exist on site and/or
,adjacent property
tetails for the roads, parking area, cul-de-sac radii, sidewalk widths, curb and gutter;
�' Dimensions & slopes provided
�rainage areas delineated ❑ Pervious and impervious reported for each ❑ Areas of high density
MP operation and maintenance agreements provided
cY Application complete ❑ Application Incomplete Returned: (Date)
Comments
May 5, 2011 Revision, Bill Diuguid

of 0 LD
Mason & Hanger Group, Inc.
1500 Spring Garden Street
_Day0mmermann Philadelphia, PA 19130
DATE 07i2412012
i NC DEPARTMENT OF ENVIRONMENTAL
T, • AND NATURAL RESOURCES.
Th 1601 MAIL SERVICES CENTER
Order RALEIGH NC 27699-1601 AUTHORIZED SIGNATURE
of E
.--.1 TWO SIGNATURES REQUIRED
FOR AMOUNTS OVER 550,000
III L?lVA3?"' 1:03110LL561: 66990053213,11
17116937 - QL-
CITIZENS BANK
CHECK AMOUNT *****-***$505.00
VOID AFTER 90 DAYS -

4
I
Phone: 859,252.9980
Fax: 859,253.0781
Q
MasonJanger
A Dayc`77.inunermann Company
Sto rmwate r
Management Report
M&H Project No. 0099.04.305
SOF Training Facility
Pope AAF, Cumberland County, North Carolina
Prepared for:
State of North Carolina
Department of Environmental and Natural Resources
Division of Water Quality
for
Stormwater Management Permit Application
Prepared by:
The Mason & Hanger Group Inc.
300 West Vine Street, Suite 1300
Lexington, KY 40507
�ESS1 p 4
a SEAL r
11440 Submittal Date:
July 2012
Revision Date:
/3� Z August 2012
Engineer of Rec6P Date
COPVRIGH 1' 2011 Mason & Hanger
This document may not he reproduced without written permission Crum Mason & I langer.

I�
Mason&Hanger S01 lrairrirrgl acdity
,,,,,,,,r;,,­­.,.'1,:,""_, Pups Vield, Cumherhurd County, North Carolina
TABLE OF CONTENTS
SECTION PAGE
GENERAL....................................................................................................................................
1
METHODOLOGY....................................................................................................... ..................
.. 1
EXISTING CONDITIONS.................................................................................................................
1
PROPOSED CONDITIONS ........ ................ ........................... ......................... ... ... I...........................
2
STORMWATERMANAGEMENT.......................................................................................................
3
TABLES
Table 1 PRE -DEVELOPED COMPOSITE RUNOFF COEFFICIENT CALCULATIONS ..................
I...... 2
Table 2 POST -DEVELOPED COMPOSITE RUNOFF COEFFICIENT CALCULATIONS .......................
2
APPENDIX
Appendix A USGS PROJECT LOCATION MAP............................................................................a.1
Appendix B. WET DETENTION BASIN CALCULATIONS..................................................................a.2
Appendix C STORMWATER CALCULATIONS.......................................................................a.3
Appendix D NRCS CUMBERLAND COUNTY SOIL SURVEY MAP...................................................a.4
Appendix E. SUBSURFACE EXPLORATION AND GEOTECHNICAL ENGINEERING REPORT.................a.5
;t foson X 11anger Page - i -

I�
Mason&Hanger SOF Training Facility
Pope Field Cumberland County, North Carolina
GENERAL INFORMATION
The project is located within Pope Army Air Field. The site is bound on the north by Reilly Road, the east
by Harley Pope Road (formerly Manchester Road), the south by an asphalt road located just south of
building no. 519 and on the west by an existing manmade ditch. The project consists of one (1) new
13,627 SF SOF Training Facility building located at the southwest intersection of Reilly Road and Harley
Pope Road (formerly Manchester Road). And the construction of a 25'x25' (625 SF) pavilion training area
located just west of the proposed building. In addition the project consists of one (1) 60-space asphalt
parking lot and associated sidewalks and equipment pads.
METHODOLOGY
Per the North Carolina Department of Environmental and Natural Resources (NCDENR), the approved
methods used in stormwater calculations are as follows:
Tahle 3-1
Iytnuttiity o Stormwater Cakiiia*ions
Calculation of:
Section
Allowable Afethods
Peak Floc-
32
Ralianal Method
Rtul di'volmle
3.3
`hn};leMethod
Diwroto S(_.R CIliV? `mnl7P1 Lfrtllnrl
5tc1�; e Vclurr:e
3.4
`ta e-Storage Table
Hydr.lellio Parfno•rn.11W1a of flip
; n
>1'air FrIll.)rin,l;
OWIA Derive
01ifitie aluotiwi
`•r,t�a Stmnua-r�:Srh,lr�r
:3.6
Chainsaw Ro„ lino
011lrn��<'
challtl Pl Cipr471Plrp
3.7
M.itlnin: F :1dt1M:
tiuteient Loadilig
3.3
DLYO Nettie TN Fxport Wo:ksheel
DWQ Tar-PcaTlico Nutrient Ex lost Woikslieet
pUltlt:.11! Re.nu%, l Uf BMP-�
3.9
4l.aed-dully BMPs
Multiple Erdr.age areas
UNIP5 m P,lAall&l
BM Ps 111 Series
Note: Ueslgners may adopt dlflelent Calculation methods, Ilut the Method chosen niust -.)1OV1de
aatut.tlatlt or sl,pater pro k,,:Uon tllut the ivaEttods pro-sontod have.
Ref: NCDENR Stormwater BMP Manual
All methodology follows the guidelines set by the Corp of Engineers Savannah District and NCDENR.
EXISTING CONDITIONS
The existing site where the training facility and associated supporting facilities is to be constructed is
approximately 4,0 acres. The entire area considered for the purpose of the stormwater calculations is
approximately 5.38 acres. The site slopes generally from east to west, with an existing manmade
drainage ditch along the west side of the site. The ditch drains in a northerly direction to two (2) 36-inch
pipes traversing under Reilly Road. USGS maps indicate that the area north of Reilly Road drains toward
Tank Creek (18-23-27) which eventually empties into Little River (18-23-(24)). Information obtained from
NCDENR indicates that Little River as well Tank Creek are Class C stream classification.
The existing soils on the site were obtained from the Corp of Engineers, Savannah District Subsurface
Exploration and Geotechnical Engineering Report. The soil borings generally displayed root debris and a
trace of organics within the first foot below the ground surface. Subsurface soils for all sites consist
primarily of silty sands (SM) and poorly -graded sands (SP). Groundwater was encountered during drilling
at depths ranging from 12 feet to 14 feet below ground surface near the building footprint. In borings near
the parking lot and access drive, groundwater ranged from 3.5 feet to 8 feet below ground surface. In
one boring, no groundwater was detected. The seasonal high water table in the vicinity of the proposed
Mason & Hunger Page I of 3

I1
I` I,
Mason&Hangar SOF Training Facility
; lka :a...,,.,,...a-,k.. Pole Field, Cumberland County, North Carolina
wet -detention basin is estimated to be at 172.80. This elevation was estimated from water level readings
after drilling, moisture content and soil stratification shown in the bore hole at the detention basin.
The pre -developed composite runoff coefficient calculations are given in Table 1.
TABLE 9 PRE -DEVELOPED COMPOSITE RUNOFF COEFFICIENT
CALCULATIONS
COVER AND DESCRIPTION
C
AREA
C X A
Concrete/Asphalt/Roof
0.9
0.71
0.639
Forest
0.2
0.82
0.164
Grass
0.3
3.85
1.155
TOTAL
5.38
1.958
The data provide yields a weighted C value (Cw) of 0.36 for the existing conditions.
Using the rational method and the input criteria previously described, the peak flow for the existing
conditions one-year, 24-hour storm is 4.41 cfs.
PROPOSED CONDITIONS
As previously discussed, the project includes a 13,627 SF SOF Training Facility building, 625 SF pavilion
training area, a 60-space asphalt parking lot, and associated sidewalks and equipment pads. The
improvements to the site separated the original subbasin into seven (7) subbasins. The post -developed
composite runoff coefficients calculations for each subbasin are given in Table 2.
TABLE 2 POST -DEVELOPED COMPOSITE RUNOFF COEFFICIENT
CALCULATIONS
COVER AND DESCRIPTION C
AAREA
C X A
Al
Concrete/Asphalt/Roof
0.9
0.1
0.09
Forested
0.2
0.05
0.01
Grass
0.3
0.73
0,219
TOTALS:
0.88
0.319
A2
Concrete/Asphalt/Roof
0.9
0.15
0.135
Forested
0.2
0.18
0.036
Grass
0.3
0.48
0.144
TOTALS:
0.81
0.315
A3
Concrete/Asphalt/Roof
0.9
0,18
0.162
Forested
0.2
0,13
0.026
Grass
0.3
0.84
.252
TOTALS:
1.15
0.44
A4
Concrete/Asphalt/Roof
0.9
0.68
0.612
Forested
0.2
0
0
Grass
0.3
0.44
0.132
TOTALS:
1.12
0.744
A5
Co ncrete/As p ha It/Roof
0.9
0.81
0.729
Forested
0.2
0
0
Grass
0.3
0.09
0.027
TOTALS:
0.9
0.756
A6
Mason & llanger Page 2 of 3

I�
(N
Mason&Hanger 5O 'Training Facility
Pope Field, Cumberland Counrv, North Carolina
ConcretelAsphaitlRoof
0.9
0
0
Forested
0.2
0
0
Grass
0.3
0.31
1-0.31
0.093
TOTALS:
0.093
TABLE 2 POST -DEVELOPED COMPOSITE RUNOFF COEFFICIENT
CALCULATIONS (CONT'D)
COVER AND DESCRIPTION
C
AAREA
C X A
A7
ConcretelAsphattlRoof
0.9
0.05
0.045
Forested
0.2
0
0
Grass
0.3
0.17
0.051
TOTALS:
0.22
0.096
The data provide yields a weighted C value (Gu) of 0.37, 0.39, 0.39, 0.67, 0.84, 0.30, and 0.44 for
subbasins All, A2, A3, A4, A5, A6, and A7, respectfully for the proposed conditions.
Using the rational method and the input criteria previously described, the peak flow for the proposed
conditions one-year, 24-hour storm is 8.35 cfs. This requires the use of stormwater best management
practices (BMPs) to reduce the post -development flow rate to equal to or less than the pre -development
flow rate.
STORMWATER MANAGEMENT
The BMP utilized by this project to minimize the adverse affects of the development is a wet detention
basin. The basin reduces the peak post -development from 8.35 cfs to 2.94 cfs which is below the pre -
development flow rate. The detention basin will also serve as a sediment basin during construction.
The wet detention basin will include a permanent pool volume of 25,225 cf and a temporary additional
volume of 7,500 cf. This treatment volume corresponds to a design TSS removal of 90%. In addition,
most drainage leading to the wet detention basin will be carried via grassed swales, and discharged into
the forebays over stone riprap. These swales will further reduce overall TSS.
The drawdown in the wet detention basin is provided via a 1.5" orifice. This outlet will drain the temporary
pool in approximately 2.01 days.
As the permanent pool elevation is above the estimated seasonal high water table elevation, a
geocomposite clay liner will be utilized to maintain the permanent pool elevation. The liner shall be
installed over the entire surface of the forebay and the wet detention basin below elevation 175.90
(permanent pool elevation). A minimum 12" of topsoil should be applied over the liner to ensure
adequate plant growth.
For additional design information, refer to the Wet Pond supplemental information form and calculations
in Appendix C.
Mason & hanger Page 3 of 3

NCRENR.
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Charles Wakild, P.E.
Governor Director
August 3, 2012
Mr. Don Higgins
Day ii Zimmerman
125 The Parkway, Suite 400
Greenville, NC 29615
Subject: Request for Additional Information
Stormwater Project No. SW6120706
SOF Training Facility (Pope)
Cumberland County
Dear Mr. Higgins:
Dee Freeman
Secretary
The Division of Water Quality Central Office received a request to modify the Stormwater Management Permit for the subject
project on July 27, 2012. A preliminary review of that information has determined that the application is not complete. The
following information is needed to continue the stormwater review:
1. The permanent pool (PP) elevation should be within 6 inches of the seasonal high water table (SHWT). The supplement
indicates the PP is lower than SHWT while the plans indicate the PP is able the SHWT. Please revise the design and fix
any inconsistencies. Also, I could not locate the SHWT in the soils report.
2. The length of the flowpath to width ratio needs to be at least 3:1 in make sure the stormwater is not short circuited
through the basin. The second forebay looks to not be providing the 3:1 flowpath. Please make sure both forebays are
providing the 3:1 flowpath.
3. A few inconsistencies were noted on the plansheets. The outlet detail on CG500 does not match the details on CG504.
Also, the details on CG504 should match. One is missing the orifice and the trash guards are different. Please revise the
details to be accurate.
4. Please show proposed drainage easements and public right of way on the plans.
The requested information should be received by this Office prior to August 17, 2012, or the application will be returned as
incomplete. The return of a project will necessitate resubmittal of all required items, including the application fee. If you
need additional time to submit the information, please send your request, including date by which you expect to submit the
required information, to my attention. The Division is allowed 90 days from the receipt of a completed application to
issue the permit.
Please reference the State assigned project number on all correspondence. New original documents must be provided and
copies are not acceptable. If you have any questions concerning this matter feel free to contact me at [phone] or
[e-mail].
Sincerely,
Brian Lowther
Environmental Engineer
cc: Fayetteville Regional Office
Stormwater Permitting Unit Files
ec: David Heins, Environmental Division Chief (DPW)
Wetlands and Stormwater Branch One
1617 Mail Service Center, Ralegh, North Carolina 27699.1617 NorthCarolina
Location: 512 N. Salisbury Sl, Raleigh, North Carolina 27604
Phone: 9IM07-6300 l FAX: 91M07.6494 Naturally
intemet: www.nwataroualiiy.o_-m