20090430 Ver 1_More Info Letter_20100525

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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
May 25, 2010
DWQ Project#09-0430
Johnston County
CERTIFIED MAIL: RETURN RECEIPT REQUESTED
Mr. Ray Blackmon
Johnston County Airport Authority
3149 Swift Creek Road
Smithfield, NC 27577
Subject Property: Johnston County Airport Extended Runway Safety Area
Reedy Branch [030404, 27-45-10, C,NSW]
REQUEST FOR MORE INFORMATION: STORMWATER MANAGEMENT PLAN
Dear Mr. Blackmon:
On February 24, 2010,the Division of Water Quality(DWQ) issued a 401 Water Quality
Certification and Riparian Buffer Authorization to impact 18.21 acres of wetland, 685 linear feet of
perennial stream, 44,496 square feet of Zone 1 Neuse Riparian Buffer and 28,474 square feet of Zone
2 Riparian Buffer to construct the subject development in Johnston County. In order to meet
Condition 7,of the 401 Certification for this project, a stormwater management plan, dated April 16,
2010,was received by the DWQ on April 18, 2010. The DWQ has determined that your stormwater
management plan was incomplete as discussed below.
Additional Information Requested:
1. Please address the following issues on all plan sheets:
a. Only final construction drawings will be accepted(not preliminary plans).
b. All stormwater pipes must be shown, with sizes,lengths and slopes called out.
c. Accurate swale footprints(actual widths)must be shown(i.e.,the extent of the freeboard
location).
d. Drainage easements for the swales that extend a minimum of 10 feet beyond the
freeboard location must be shown.
2. Please provide calculations to support the times of concentration that are listed as greater than
five minutes.
401 Oversight/Express Review Permitting Unit One
1650 Mail Service Center,Raleigh,North Carolina 27699-1650 NorthCarolina
Location.2321 Crabtree Blvd.,Raleigh.North Carolina 27604
Phone.[phone] FAX.[phone] atura!!�
Internet:http://h2o.enr,state.nc,us:lncwetlands,
Ar Enuai Opportunity`.Affirmative Action Employer

Johnston County Airport Authority
Page 2 of 2
May 25,2010
3. Please address the following issues with Swale#3:
a. The use of the level spreader downslope of the splitting device for Swale#3 is
inappropriate.
b. The parallel swales proposed must be parallel for their entire treatment ength.
c. The swale on the east side does not retain a constant side slope throughout its entire
length.
d. The cross-section of Swale#3 is inconsistent with the plan view.
e. The cross-section must be to scale (please state the scale).
4. Please address the following issues with Swale#5:
a. The swale on the southeast side does not retain a constant side slope throughout its entire
length.
b. The cross-section must be to scale(please state the scale).
5. For Swale#6,are drop inlets installed at every transition point, i.e., from Swale 6A to Swale 6B,
Swale 6B and Swale 6C, and so on? The design implies this is the case. If so, these devices must
be shown on the plans. The entire length of Swale 6 must be shown on the plans per Item 7
below.
6. Please provide ALL REQUIRED ITEMS for ALL PROPOSED SWALES, including:
a. A separate required items checklist for each swale.
b. Scaled cross-sections that show elevations for water depth and freeboard.
c. Proposed topographic contours for ALL swales. You will need to provide grading in any
locations where existing swale geometry does not meet the,standards in the BMP Manual.
d. Correct swale dimensions and boundaries of the drainage easements.
e. Scaled section views.
The DWQ will require the above additional information to finalize review of the stormwater
management plan for the subject property. Please provide the following information so that we may
continue to review your project. You are welcome to contact meat 919-715-3425 if you have
questions.
Sincerely,
Annette Lucas, PE
401 Oversight/Express Review Permitting Unit
AML/aml
cc: Lauren Witherspoon, DWQ Raleigh Regional Office
USACE Raleigh Regulatory Field Office
File Copy
Daniel Ingram, WK Dickson&Co., Inc., 720 Corporate Center Drive, Raleigh,NC 27607
Filename: 090430Joh nstonCountyAirportRunwaySafetyArea(Johnston)_S W_Hold.docx

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JOHNSTON CO AIRPORT AUTHORITY
RAY BLACKMON 5/27/10
3149 SWIFT CREEK RD
SMITHFIELD NC 27S77 3.R-
13viceType
DWQ 09-0430 JOHNSTON COUNTYCertified Mail ❑Express Mail
I Registered ❑Return Receipt for Merchandise
❑Insured Mail ❑C.O.D.
4. Restricted Delivery?(Extra Fee) -- ❑Yes
2. Article Number
(Transferfrom service tatx 7 0 0 9 2 8 2 0 0004 4137 2278
PS Form 3811,February 2004 Domestic Retum Receipt 102595-02-M-1540

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NC DENR DIVISION 01, WATER QUALITY
401 OVERSIGHT/EXPRESS UNIT
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RALEIGH,NC 27604