20070059 Ver 1_More Info Received_20070329

DIAL CORDY
ANU ASSOCIATES 1NC
Er~uir~~n~r~cntc~l Cr~r~sl~lrci~~ts
27 March 2007
~~~ aI ~ ~~
Mrs. Noelle Lutheran
Environmental Specialist III ~~~~ ~ ~ ~~~
Division of Water Quality
127 Cardinal Drive ~nA~~c~. ,~U1~Tfi~tA~lA ~fit~R~4Ii
Wilmington, NC 28405
Re: Hawkeswater at the River Subdivision -Nationwide 14 Permit Application
Action ID 2007125-010
Dear Mrs. Lutheran:
We have received your letter dated 8 March 2007 regarding our Pre-Construction
Notification for the proposed construction of the Hawkeswater at the River
Subdivision. This letter serves to address your concerns so that formal review of
the application may continue.
In Section 1 of your response, you expressed concerns about stream impact
calculations, pointing out that it did not appear stream reaches proposed for
impact were measured along the centerline of the normal flow channel. Streams
proposed for impacts were, in fact, measured along the centerline of the channel.
The endpoints of the proposed impacts to the stream channel are indicated on
the plan and profile drawings for crossings C and D. Measurements indicated in
the tables on the Index Map reflect the stream lengths measured along the
channel centerline between the endpoints indicated on the plan and profile
drawings. Per your request, the road crossings have been slightly modified to
ensure streams and wetlands upstream and downstream of the proposed
impacts are not degraded. Modifications include the repositioning of culverts at
Crossing C to provide better alignment with the normal stream flow, addition of
retaining walls at Crossings C and D to reduce erosion, and placement of
"Terratubes" at each crossing to further remove any sediment that finds its way
into the streams. The attached letter from Mr. Larry Gilman of Cape Fear
Engineering elaborates on the design specifications at each crossing. New plan
and profile drawings for the two modified road crossings are also attached. The
modification of the road crossings did not result in additional impacts to streams
or wetlands.
FIRST UNION BUILDING, SUITE 6OI • ZOI NORTH FRONT STREET • WILMINGTON, NORTH CAROLINA 23401
910-251-9790 • FAx [phone] • E-h1A1L infnC~clialmndycom
OFFICES ]ACKSONVILLE, FLORIDA • ACLANTA, GEORGIA • CHARLESTON, SOUTH CAROLINA

In Section 2, you pointed out that impacts to 150 linear feet of stream or more
requires stream mitigation. Although design of the stream crossings have been
modified, the stream lengths proposed for impacts remains unchanged. Since
less than 150 feet of stream impacts are proposed, no stream mitigation will be
necessary.
Section 3 requests the inclusion of the proposed preservation language to be
used to deed restrict lots and preserve remaining wetlands on the site. The
preservation language is currently being drafted and will be provided to you
within thirty days of permit issuance.
Having addressed your concerns and provided you with the information you
requested, this letter and the enclosed attachments should complete the
application. Please proceed with the processing of the application. Should you
have any questions, please give me a call at the office [phone], or on my
cell phone [phone]. Thank you for your time and attention to this matter.
Sincerely,
Jeffrey T. Coward
Natural Resource Specialist
cc: John Lancaster
Cindy Karoly, NCDWQ
J06-0961
Enclosures

03-26-'87 17:2 FBOM-9113831045 91~3831~45
~~ CAPE FEAR
' Engineering, lnc.
757 F'oole Road, Suits i0~
&olVille, NC 28457
To: Noelle Lutheran
Division of'Wattr Quality
127 Cardinal Drive
Wilmington, North Caroiina 28405
Ite: DWQ Project # 070059 Brunswick County
" ldawkeswater"
March 25th,2007
T-897 Pt7~1/001 F-3t~2
17C~ Co~~
p'1 -0059
In response to your letter of March 8c°, concerning the "I-Iawkeswater" application.
rlease consider the fpllowing design changes and additional information: These
changes will ensure normal flow and bank full events.
'll~etlands Crossing "G": The design runoff from a 10 yr frequency storm is 53.93 efs.
Presently, this crossing is designed with two ti0 inch cross culverts at a slope of 1% which
results in a flow of Z7 efs per pipe at a height of 13 inches with a resulting velocity of 8.57 fps.
It is proposed to reduce the percent of grade at which the cross culverts are laid to one tenth of
l % ;resulting in a reduced velocity of 2.7 fps. A new plan and profile for this crossing are provided
which also moves the twin 60" culverts toward the center of the streambed to provide better
alignment with normal stream flow.
Wetlands Crossing "D: The design runoff from a 10 yr frequency storm is 60 cfs.which results in a
flow of 15 efs ptr pipe at a height of 11 inches in the 42 inch pipe with a resulting velocity of 7.51 efs.
Tt is proposed to reduce the percent of grade at which the four 42 inch pipes are laid to one tenth
of 1 °/a resulting in a reduced velocity of 2.37 fps.
In lieu of bridges, we are proposing "Keystone" retaining walls at crossings "C" and "D" to
stabilize the associated fill package. Silt fences lutve been added, both upstream and downstream,
of each crossing to protect the wetlands and the stream. In addition, downstream, of each crossing,
we are adding "Terratubes"to further remove any sediment .
it is the professional opinion of this office that these reduced velocities and S & E controls
iviil safeguard the stream and the adjacent wetlands and etnbanltncnt.
Sincerely,
~~Z
awrence R, ilman P.E.
l;or "Cape )~ear )rngintering"
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