SW6091202_HISTORICAL FILE_20100104

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW 6QO_ AooA
DOC TYPE
❑ CURRENT PERMIT
❑ APPROVED PLANS
HISTORICAL FILE
❑ COMPLIANCE EVALUATION INSPECTION
DOC DATE
YYYYMMDD

2301 Remwds Dn" 919.881.9939
a Suite 200 919.881.9923 fox
01 Dewberry Raleigh, NC 27607 ww d wb rty coo
January 4, 2010
Mr. Mike Randall
NCDENR — Division of Water Quality
Archdale Building
512 N. Salisbury Street
Raleigh, NC 27604
Reference: Training Support Center (TSC)
NCDENR Stormwater Permit Package
Permit No. SW6091202 - Request for Additional Information
Dear Mr. Randall:
Please find the following responses to the Request for Additional Information dated December 31, 2009:
1. As we discussed the BUA and DA for the application and supplement forms do not agree. Please
correct and resubmit either the Supplement Form or the Application Form Page 3 of 6.
Response: The application form Page 3 has been revised to match the supplement form. See
attached.
2. The supplement form indicates that the driving head is 1.42 ft. Please not that the BMP manual
requires Ho/3 (page 3-11). Please either correct the supplement form or provide a narrative
explaining why you used a driving head of 1.42 ft in lieu of 0.47 ft per the BMP manual.
Response: Supplemental Form `Driving Head' has been corrected to 0.47 ft. See
attached.
3. The supplement form indicates the storage discharge rate = 0. 15cf/s. For 16,514 cf to discharge
in 2-5 days (86,400 seconds/day) the discharge rate will need range of 0.038 and 0.095 cf/s.
Please either correct the supplement form or provide a narrative explaining why you used a
discharge rate of 0.15 cf/s.
Response: Original value of 0.15 cfs was maximum flow using 2.2 inch orifice and 1.42
ft maximum head conditions. Supplemental Form `Discharge' has been corrected to
0.095 cfs average daily flow using 2.2 inch orifice. BMP recovery time remains 2.05
days. See attached.
4. Surprisingly, 1 calculated a 2.26 inch orifice for a two day draw down time. So I'm not sure how
you came up with 2.2 inch orifice. Certainly anything smaller than 2.26 inches will meet the
draw down time requirements. I'm good with the 2.2 inch orifice.
Response: No action required.
For your review we have enclosed the following:
• Revised application form page 3 of 6
• Revised wet detention basin supplement form
Dewberry & Davis, Inc.

2301 Remoods Drive 919.881.9939
g Suite 200 919.881.9973 fax
Dewberry Raleigh, NC 27607 www.dewbcrry.com
Please feel free to give me a call should you have any questions or need any additional information.
Sincerely,
Dewberry & Davis, Inc.
V' .'.t e w
Virginia Russell, PE, LEED AP
Project Engineer
P:�50022460\AdmtPermits\Stormwater\2009.12.31 - First Round Comments from NCDENR\2010.01.04 - Comment Responses
to NCDENR.dmx
Dewberry & Davis, Inc.

Wet Pond Calculations
Water Quality Treatment Volume
Volume = 3630 * Rd * Rv * A
Where Rd = Design Storm
Rv = 0.05 + 0.9 * I
I = Impervious Portion / Drainage Area
Ac = Area in Acres
Example
Volume = 3630 * 1.0 * [0.05 + 0.9 * (197,330/315,810] * 7.25 = 16,115 cf
Surface Area (SA)
SA = DAM 00 * Ratio
DA = Drainage Area
Ratio from Table 10-1, 10-2, 10-3 or 10-4 is based on BUA, average depth, TSS and removal
Example
SA = 7.25 acres/100 * 3.4 +/- (Table 10-3 for 90% TSS removal, 3 ft average depth, and 64% BUA)
SA = 0.24 acres 10,737 sf
Discharge Rate (cfs) for 2 to 5 days
Discharge Rate (2-5 days) = Water Quality Treatment Volume/(seconds/day)/(number of days)
Example (2-5 days)
Discharge Rate (2 days) = 16,115 cf / (86,400 (sec/day) / 2 days = 0.093 cfs
Discharge Rate (5 days) = 16,115 cf / (86,400 (sec/day) / 5 days = 0.037 cfs
Orifice Size
Q=CdA[2gHo]A0.5 or A=Q/(Cd(2gHo)A0.5
Example
A=Q/Cd*(2gHo)A0.5
Where
Q = from 0.037 to 0.093 cfs (discharge rate for 16,115 cf in 2 to 5 days)
Note: Q must be less than or equal to the pre -development discharge rate for the 1 year 24 hour peak
flow where Q = CIA (12.07 calculated)
Ho = 1.42 / 3 [ (255.42- 254.0)/3 = 1.42 ] = 0.47
A = Q / (Cd (2 g HO) A 0.5 =0.093/[(0.6*(2* 32.2 * 0.47) A 0.5] = 0.028 ft' (2 day draw down)
D (Diameter Orifice feet) _ (4 A / 3.14) A 0.5 = 0.189 ft
D (Diameter Orifice inches) = 0.189 ft * 12 inches/feet = 2.26 inches +/-

WA
r
NC®ENR
North Carolina Department of Environment and Natural Resources
Division of Land Resources
James D. Simons, PG, PE
Director and State Geologist
Land Quality Section
October 1, 2009
LETTER OF APPROVAL
EXPRESS REVIEW OPTION
Directorate of Public Works
Attn: Gregory G. Bean
2175 Reilly Road Stop A'_.._,
Fort Bragg, NC 28310-5000
RE: Project Name: FB-Training Support Center Acres Approved: 7.25
Project ID' CUMBE-2010-040
County: Cumberland Fort Bragg Gruber Road
River Basin: Cape Fear Stream Classification: Other
Submitted By: Dewberry & Davis, Inc.
Date Received by LQS: 9/24/2009
Plan Type: Express
Dear Mr. Bean:
Beverly Eaves Perdue, Governor
Dee Freeman, Secretary
OC. ? 2009
DEli'a s e . :r-,' ;,_,
This office has reviewed the subject erosion and sedimentation control plan. We find the plan to
be acceptable and hereby issue this Letter of Approval. The enclosed Certificate of Approval must be
posted at the job site. This plan approval shall expire three (3) years following the date of approval, if no
land -disturbing activity has been undertaken, as is required by Title 15A NCAC 4B .0129.
Title 15A NCAC 4B .0118(a) requires that a copy of the approved erosion control plan be on file
at the job site. Also, this letter gives the notice required by G.S. 113A-61.1(a) of our right of periodic
inspection to insure compliance with the approved plan.
North Carolina's Sedimentation Pollution Control Act is performance -oriented, requiring
protection of existing natural resources and adjoining properties. If, following the commencement of this
project, the erosion and sedimentation control plan is inadequate to meet the requirements of the
Sedimentation Pollution Control Act of 1973 (North Carolina General Statute 113A-51 through 66), this
office may require revisions to the plan and implementation of the revisions to insure compliance with the
Act.
The developer is responsible for obtaining any and all permits and approvals necessary for the
development of this project prior to the commencement of this land disturbing activity. This could include
agencies such as the Division of Water Quality's stormwater regulations, their enforcement requirements within
Section 401 of the Clean Water Act, the Environmental Protection Agency and/or the U.S. Army Corps of
Fayetteville Regional Office 225 Green Street — Suite 714, Fayetteville, North Carolina 28301
Phone: [phone] / FAX: [phone]-Internet: http://www.dIr.enr.state.nc.us/pages/landqualitysection.html
An Equal Opportunity / Affirmative Action Employer — 50% Recycled / 10% Post Consumer Paper

Letter of Approval
Directorate of Public Works
October 1, 2009
Page 2 of 2
Engineers' jurisdiction of Section 404 of the Clean Water Act, the Division of Solid Waste Management's landfill
regulations, local County or Municipalities' ordinances, or others that may be required. This approval cannot
supersede any other permit or approval; however, in the case of a Cease and Desist Order from the Corps of
Engineers, that Order would only apply to wetland areas. All upland areas would still have to be in compliance
with the N.C. Sedimentation Pollution Control Act.
If any area on site falls within thejurisdiction of Section 401 or 404 of the Clean Water Act, the
developer is responsible for compliance with the requirements of the Division of Water Quality, the Corps of
Engineers and the Environmental Protection Agency (EPA) respectively. Any erosion control measures that fall
within jurisdictional wetland areas must be approved by the aforementioned agencies prior to installation. The
Land Quality Section must be notified of a relocation of the measures in question to the transition point between
the wetlands and the uplands to assure that the migration of sediment will not occur. If that relocation presents a
problem or contradicts any requirements of either DWQ, the Corps, or the EPA, it is the responsibility of the
developer to inform the Land Quality Section regional office so that an adequate contingency plan can be made to
assure sufficient erosion control remains on site. Failure to do so will be considered a violation of this approval.
Acceptance and approval of this plan is conditioned upon your compliance with Federal and State
water quality laws, regulations, and rules. In addition, local city or county ordinances or rules may also
apply to this land -disturbing activity. This approval does not supersede any other permit or approval.
Please be aware that your project will be covered by the enclosed NPDES General Stormwater
Permit NCGO 1000 (Construction Activities). You should first become familiar with all of the
requirements for compliance with the enclosed general permit.
Please note that this approval is based in part on the accuracy of the information provided in the
Financial Responsibility Form, which you provided. You are requested to file an amended form if there
is any change in the information included on the form. In addition, it would be helpful if you notify this
office of the proposed starting date for this project. Please notify us if you plan to have a preconstruction .
conference.
Your cooperation is appreciated.
Sincerely,
Sally McKinney,
Land Quality Section
Enclosures: Certificate of Approval
NPDES Permit
cc: Dewberry & Davis, Inc.
Craig Lantz, Directorate of ENV & DPW
Belinda Henson, Division of Water Quality
Land Quality Section - Fayetteville Regional Office File