20041808 Ver 3_More Info Letter_20090902

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NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
September 2, 2009
DWQ EXP # 04-18080
Stanly County
CERTIFIED MAIL: RETURN RECEIPT REQUESTED
Mr. David Griffin
Stanly County Airport Authority Manager
38512 Aviation Dr
New London, NC 28127
Subject Property: Stanly County Airport New Terminal Building
REQUEST FOR MORE INFORMATION
Dear Mr. Griffin:
On August 31, 2009, the Express Review Program of the Division of Water Quality (DWQ) received your
application dated August 18, 2009, to fill or otherwise impact 0.09 acres of wetland and 274 linear feet of
intermittent stream in the Yadkin-Pee Dee river basin to construct the proposed "Stanly County Airport
New Terminal Project". The DWQ has determined that your application will require additional
information. Please provide the following information so that we may continue to review your
project and prevent return of your application as required by 15A NCAC 2H .0506:
Additional Information Requested
Stormwater Best Management Practices (BMP):
a. Please specify on the plan sheets the type(s) of grass to be planted in the bioretention cell as
well as the filter strip. A non-clumping variety should be used, and please include a note that
the grass will be sod, with only a one-time fertilizer application allowed for initial
establishment.
b. Include a note on the plans and in the appropriate section on the supplement form that the
phosphorus (P) Index of the selected soil mix shall be less than 20.
c. Please use the 10-year storm to estimate the velocity in the filter strip since there is no bypass
for larger storms. The velocity shall be non-erosive. Use the rainfall intensity corresponding
to 5 minutes time of concentration instead of 10 minutes.
d. The bioretention cell dimensions and associated surface area reported on the plans and
supplement form should be corrected to match what is actually provided and correctly
reported in other places.
e. Please revise the underdrain sizing calculations as follows: (i) Use a factor of safety between
2 and 10 (5 recommended) to multiply the flow rate through the soil media. (ii) Please use the
revised equation to estimate the diameter of the underdrain pipe (factor 16 is outside the
entire bracket).
401 OversighUExpress Review Permitting Unit
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
Location: 2321 Crabtree Blvd , Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone]
Internet: http:/lh2o.enr.state.nc.us/ncwetlands/
N?orthCarolina
aturall?
An Equal Opportunity 1 Affirmative Action Employer
Stanly County Airport Authority - New Terminal Building
David Griffin
Page 2 of 2
September 2, 2009
f. Specify on the plan sheets the type of underdrain pipe being proposed, e.g. Schedule 40 or
SDR 35 smooth wall PVC, as well as the slope. (0.5% minimum recommended). See section
5.7 of the NC DWQ BMP Manual.
g. Please add a note on plan sheet 2 to indicate that stormwater runoff from the area designated
as "Future Impervious" shall be maintained as sheet flow into the adjacent grass swales and at
no point shall concentrated flow be directly discharged into the swales/ditches.
Please respond within five (5) days of the date of this letter by sending two (2) copies of the above
information in writing. The Express Review Program is a process that requires all parties to participate in
a timely manner.
This letter only addresses the application review and does not authorize any impacts to wetlands, waters or
protected buffers. Please be aware that any impacts requested within your application are not authorized (at
this time) by the DWQ.
Please contact Joseph Gyamfi or Lia Myott Gilleski at 919-733-1786 if you have any questions regarding or
would like to set up a meeting to discuss this matter.
CBK/jg
cc: File copy
Sincerely,
Cyndi Karoly, Supervisor
401 Oversight/Express Review Program
Alan Johnson, DWQ-MRO
USACE Asheville Regulatory Field Office
Chad Vernon, Talbert & Bright Inc., 4944 Pkwy Plaza Blvd., Suite 350, Charlotte, NC 28217
Ron Geiger, PE, HDR Inc., 128. S. Tryon St., Suite 1400, Charlotte, NC 28202-5004