20021157 Ver 2_More Info Received_20061107

6Zuible
6~uible & Associates, P.C.
ENGINEERING • ENVIRONMENTAL SCIENCES • PLANNING • SURVEYING
SINCE 1959
NC Division of Water Quality
Attn: Ian McMillan
1650 Mail .Service Center
Raleigh, NC 27699-1650
November 6, 2006
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RE: Warner Lot Access DWO Project # 02-1157
Response to October 23, 2006 Additional Information Request
P.O. Drawer 870
Kitty Hawk, NC 27949
Phone:[phone]
Fax:[phone]
PRINCIPALS
Sean C. Boyle, P.E.
Joseph S. Lassiter, C.E.P.
Eduardo J. Valdivieso, P.E.
ASSOCIATES
Joseph J. Anlauf, P.E.
Katherine C. Marchello, P.L.S.
DWQ Request : Please indicate the diffuse flow provision measures on the site plan and submit
diffuse flow provision worksheets (such as level spreaders) and a signed and notarized
Operations and Maintenance Agreement.
(luible Response: Diffuse flow provision measures will include the following:
Providing athree -foot wide vegetative filter strip on each side of the ten-foot wide
driveway (the crowned gravel-surfaced travel aisle). The vegetative filter stripping is a
stormwater control and treatment measure. This natural treatment technique utilizes
vegetation that filters and uses water (including surface runoff) that does not infiltrate into
the driveway gravel surface. This also promotes direct infiltration of runoff from the
gravel surface before reaching wetlands. This provision lends itself well to the project
area since the driveway is a maximum of one-foot above wetland elevation and the
driveway materials include sand and a gravel surface on the drive aisle. As with most
roads in this area, there will be no pavement. The filter strip will be seeded immediately
after driveway construction and will present the opportunity for opportunistic native
herbaceous and shrub vegetation to propagate. The site plan now includes a more
detailed cross-section indicating the vegetative filter strips and a seeding schedule.
Rip rap slope stabilization around the proposed culverts. The purpose of the two
culverted areas is to allow water to transmit through the wetlands. This is not a tidally
influenced wetland area (NCDCM has made a determination of non-coastal wetlands)
and there is no normal surface water ponding and movement. However, during heavy
rain events, the wetlands may become temporarily flooded in the lower areas. The
culverts will serve to prevent a land dam situation. The culverts will be side-by-side
twelve-inch diameter traffic rated pipes and the rip rap will add stabilization around the
pipes on each side and will reduce turbidity if there are significant flow rates through the
culverts.
The attached sealed memorandum is from Eddie Valdivieso, P.E. who has reviewed all
information for this project and concurs with the diffuse flow provisions prescribed. Please review
this information and give me a call if you have any additional questions that are not addressed.
Thanks for your attention to this project.
Sincerely,
Quible &~Asnsociates, P.C.
Brian Rubino, P.G.
CC: Kyle Barnes, DWQ
Tom Steffens, USACE

Quible & Associates, PC
P.O. Drawer 870
Kitty Hawk, NC 27949
Phone:[phone]
Fax: [phone]
eddievC~quible.com

To: Brian Rubino, P.G.
From: Eddie Valdivieso, P.E.
CC: File P06107
Date: November 6, 2006
Re: Diffuse Flow Provisions
Warner Lot Access
DWQ Project #02-1157
This is to concur with your recommendation to incorporate athree-foot wide roadside
vegetative filter strip. This strip will also function as an excellent means of evenly diffusing
runoff from the gravel road.
In response to your second request, I have evaluated the "Warner Lot Access" proposal for
determination of need for "diffuse flow provisions" at culvert locations.
Based on the subject site's flat topography, vegetation, sandy soil types and periodic
fluctuation in depth to groundwater table (potential for high groundwater condition); it is
intended for the proposed culverts to simply function as equalization pipes to allow for
shallow, non-erosive, non-concentrated flow from one side of road to the other.
Consequently, it is my professional opinion that conditions at the culvert crossings do not
warrant diffuse flow provisions.
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