20091297 Ver 1_More Info Letter_20100305

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NCDE
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North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
March 5, 2010
Project No. 09-1297
Guilford County
Ms. Yvonne Johnson
City of Greensboro
Post Office Box 3136
Greensboro, North Carolina 27402
Subject Property: Keeley Park
REQUEST FOR MORE INFORMATION: STORMWATER MANAGEMENT PLAN
Dear Ms. Johnson:
On January 5, 2010, the Division of Water Quality (DWQ) issued a 401 Water Quality Certification and
Riparian Buffer Authorization to impact 0.02 acre of wetland, 149 linear feet of unnamed tributary to
Buffalo Creek, and 2.27 acres of protected Jordan Lake buffer to facilitate improvements in Keeley Park.
In order to meet Condition 2 of the 401 Certification for this project, a diffuse flow plan, dated February
1, 2010, was received by the DWQ on February 2, 2010. Additional information to the diffuse flow plan,
dated February 15, 2010, was received by the DWQ on February 16, 2010.
The DWQ has determined that your diffuse flow plan was incomplete as discussed below.
Please provide a new, updated diffuse flow package that is complete and well-organized. The
diffuse flow package should include:
a. Clearly marked plans that depict every stormwater inlet and outlet and its associated
drainage area at a scale of 1" = 50' or larger.
b. A concise written summary of each of the outfalls with an explanation of how diffuse
flow requirements are being met under the Jordan Lake Buffer Rule.
c. A completed Level Spreader Supplement Form for each proposed level spreader with all
of the required items provide in a complete manner and at the requested scale. The level
spreader(s) must be designed correctly per Chapter 8 of the DWQ BMP Manual.
d. A completed Grassed Swale Supplement Form for each proposed grass swale that is
discharging to wetlands with all of the required items provide in a complete manner and
at the requested scale. The grassed swale(s) must be designed correctly per Chapter 14 of
the DWQ BMP Manual.
2. Please address the following issues pertaining to Level Spreader 1:
a. The level lip must be sized correctly for the filter strip vegetation. It is not clear whether
the vegetation is grassed or wooded for the first 50 feet downslope of the level spreader.
Please clarify this and modify the length if needed.
b. Please provide a bypass channel that directs high flows in a non-erosive manner to the
nearest surface water.
401 OversightrExpress 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,Yh2o.enr.state .nc.us-ncwetiandsr'
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NorthCarolina
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An Equal Cpponunav Affmna(ive Action Employer
Ms. Yvonne Johnson
Page 2 of 2
March 5, 2010
c. The profile of the level spreader must include a swale immediately upslope of the level
lip to still the water before it passes over the level spreader.
d. Please provide calculations to support the design of the bypass structure.
3. All grassed swales must be trapezoidal and side slopes may not exceed 3:1. Please update the
design if these criteria have not been met.
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 me at 919-715-3425 if you have questions or would like to set
up a meeting.
Sincerely,
C&?-
Annette Lucas, PE
401 Oversight/Express Review Permitting Unit
AML/aml
Cc: Andy Williams, Army Corps of Engineers, Raleigh Regulatory Field Office
Sue Homewood, DWQ, WSRO
Virginia Spillman, City of Greensboro, 2602 S. Elm Eugene St., Greensboro, NC 27410
File Copy
Filename: 091297KeeleyPark(Guiiford)_Diff Flow_Hold.doc