20081304 Ver 3_More Info Letter_20081218

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Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division of Water Quality
December 18, 2008
DWQ Project # 2008-13040
County: Durham
CERTIFIED MAIL: RETURN RECEIPT REQUESTED
Treyburn Corporate Park, LLC
Attn: Mr. Terry Sanford, Jr.
2200 West Main Street, Suite 900
Durham, NC 27705
Subject Property: Treyburn Walking Trail Phase 1, Durham, NC
UT to Perry Creek [030402, 27-25-(2), C, NSW]
REQUEST FOR MORE INFORMATION- Diffuse Flow/Stormwater Management Plan
Dear Mr. Sanford, Jr.:
On November 3, 2008, the Division of Water Quality (DWQ) received the diffuse flow plan prepared by
your engineer, Alan Pytcher, of Summit Consulting, to comply with the conditions of the buffer
authorization that was issued on November 13, 2008. The following additional information is needed
before the Plans can be approved:
• The drainage area of 713 is greater than that of 7A. Please indicate the outfall of 713. If 713 has a
separate outfall, the velocity should be reduced to below 2fps or consider using level spreader. If
713 drains to 7A, then the design calculations of 7A would not be correct, and need to be revised
to include flow from 713.
• Similarly the design calculations for 4A (downstream) should be analyzed taking into
consideration drainage areas of or flows from upstream channels 4A and 413.
• Please indicate the slopes in the buffer following the outfalls in channels 4A and 7A. (Using a
scale of 1 " : 40', I am getting approximately 8% for 7A buffer and 7% for 4A buffer). Which
means that the water flows from a steeper slope in channel 4A (9.1%) into a little bit flatter slope
(7%) in the buffer. On the other hand, water will flow from a much flatter slope 4.7% to 8% in
the buffer). You may have to tie both 7A and 4A to the existing channels on the other side of the
trail, or you may have to install a level spreader to follow the contours on the same side of the
channels, especially when the upstream drainage areas or flows have been accounted for in the
design calculations of the downstream channels.
• Include photos of the existing vegetation in the buffer at the outfall of channels 4A and 7A.
• With respect to channel 5, you could still discharge into the existing channel as you propose.
However, it is still required that the 10-year storm velocity prior to discharging into the
existing channel shall be less than 2fps. So please consider revising channel 5 as well.
401 Oversight/Express Review Permitting Unit
1650 Mail Service Center, Raleigh, North Carolina 27699-1650
2321 Crabtree Boulevard, Suite 250, Raleigh, North Carolina 27604
Phone: [phone] / FAX [phone] / Internet: http://h2o.enr.state.nc.us/newetlands
NorthCarolina
Naturally
An Equal Opportunity/Affirmative Action Employer - 50% Recycled/10% Post Consumer Paper
Please respond in writing within 30 calendar days of the date of this letter by sending three (3) copies of
this information in writing. If you will not be able to provide the requested information within that
timeframe, please provide written confirmation that you intend to provide the requested information, and
include a specific timetable delineating when the requested materials will be provided. If we do not hear
from you in 30 calendar days, we will assume that you no longer want to pursue this project and we will
consider the project as returned.
This letter only addresses the Diffuse Flow/Stormwater Management Plan review and does not authorize
any impacts to wetlands or streams until the plans are approved. Please call Joseph Gyamfi at 919-733-
1786 if you have any questions regarding these issues.
Sincerely,
Cyndi B. Karoly
401 Oversight/Express Review Permitting Unit
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cc: Lauren Witherspoon, DWQ Raleigh Regional Office
File Copy
Alan Pytcher, Summit Consulting, 1000 Corporate Drive, Suite 101, Hillsborough, NC 27278
Matt Matthews, DWQ Wetlands and Stormwater Branch
Filename: 081304v3TreybumWalkingTrail(Durham)S W_On_Hold
¦ Complete items 1, 2, and 3. Also complete
item 4 if Restricted Delivery is desired.
¦ Print your name and address on the reverse
so that we can return the card to you.
¦ Attach this card to the back of the mailpiece,
or on the front if space permits.
1. Article Addressed to:
Treyburn Corporate Park, LLC
Attn: Mr. Terry Sanford Jr.
2200 West Main Street Suite 900
Durham, NC 27705
DWQ# 2008-1304-v3-Durham
A.
? Agent
? Addressee
-19 Re iv (Printed ame) C. Date Deliv ry
D. Is delivery address different from item 1? 10 Yes
If YES, enter delivery address below: ? No
3. Service Type
T Certified Mail ? Express Mail
Registered Return Receipt for Merchandise
? Insured Mail C.O.D.
4. Restricted Delivery? (Extra Fee) ? Yes
2. Article Number
(Transfer from servlcelab 7008 1830 0004 1353 6272
PS Form 3811, February 2004 Domestic Return Receipt 102595-02-K&1540
UNITED STATES POSTAL SERVICE

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NC DENR Division of Water
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401 Oversight/Express Unit
2321 Crabtree Boulevard suite250
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