20080080 Ver 1_Other Agency Comments_20080213

United States Department of the Interior
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FISH AND WILDLIFE SERVICE
Asheville Field Office
160 Zillicoa Street
Asheville, North Carolina 28801
February 13, 2008
Mr. Brian Wrenn
North Carolina Division of Water Quality
Central Office
2321 Crabtree Blvd., Suite 250
Raleigh, North Carolina 27604
Dear Mr. Wrenn:
Subject: Proposed Pipe Extension on NC 218, 300 Feet West of the US 601 South Intersection
in Union County, North Carolina (WBS Element No. IOB.109011)
The following comments are provided in accordance with the provisions of the Fish and Wildlife
Coordination Act, as amended (16 U.S.C. 661-667e), and section 7 of the Endangered Species
Act of 1973, as amended (16 U.S.C. 1531-1543) (Act).
According to the information in the 401 Water Quality Certification Permit Application
(Application) for the subject project, the North Carolina Department of Transportation (NCDOT)
proposes to extend a 36-inch reinforced concrete pipe by eight feet. The purpose of the proposed
work is to improve roadway safety by eliminating a sharp drop-off and failing shoulder located
on the north side of this crossing. The project is located on NC 218 in Union County. Because
of the construction of this project, there will be eight feet of permanent impacts to an unnamed
tributary of Goose Creek. Goose Creek is about 1.05 miles downstream from this crossing and is
designated and occupied Critical Habitat for the federally endangered Carolina heelsplitter
(I asmigona decorata). We conducted a site visit on February 5, 2008.
We are concerned that the current pipe is not appropriately sized for the existing stream channel.
Inappropriately sized or placed culverts at stream crossings can increase the risk of sediment
production and delivery to in-stream habitat. Undersized culverts cannot accommodate
high-flow events without increasing the water velocity exiting the pipe, which promotes scouring
on the downstream side. Increased water velocity can hinder fish passage through the culvert
and generally results in downstream scour that erodes stream banks and leaves the culvert
perched. A scour hole and perched outlet were observed at this crossing.
Based on our past meetings with the town of Fairview, it is our understanding that there is a high
likelihood of new commercial and/or residential development occurring in the near future within
the watershed of the subject unnamed tributary. This will lead to increased impervious surface
and storm water runoff into the tributary, likely resulting in further stream channel and bank
scour at the project site. Extension of the existing undersized culvert will only exacerbate the
existing problem. Accordingly, we recommend replacing this culvert with a bottomless
structure. Bottomless culverts do not need to be buried, thereby restoring the natural creek
substrate and not further disturbing the streambed. The new culvert should be sufficiently sized
to mimic the natural stream functions and habitats located at the crossing site; allow for water
depth, volume (flow), and velocity levels that will permit aquatic organism passage; and
accommodate the movement of debris and bed material during bank-full events. Widening the
stream channel must be avoided. The culvert should be designed and installed at the same slope
as the stream grade in order to maintain an acceptable water velocity for fish passage, and the
stream substrate characteristics should be retained within the culvert. We also recommend the
use of multiple barrels (in addition to the base-flow barrel), placed on or near stream bank-full or
floodplain bench elevation in order to accommodate floodwaters within the stream corridor.
These should be reconnected to floodplain benches as appropriate. This may be accomplished
by using sills on the upstream end to restrict or divert flow to the base-flow barrel(s).
Measures to control sediment and erosion should be installed before the project begins. Grading
and backfilling should be minimized; and, if possible, existing vegetation should be retained in
order to maintain shoreline cover for fish and wildlife. Disturbed areas should be revegetated
with native grasses and tree species as soon as the project is completed.
We believe that if the above recommendations are implemented we can concur with a
determination of "not likely to adversely affect" for the Carolina heelsplitter and its designated
critical habitat for this project. However, if it is determined that implementation of our
recommendations is not feasible; we believe further consultation under Section 7 of the Act will
be necessary.
If we can be of assistance or if you have any questions, please do not hesitate to contact Mr. Troy
Wilson of our staff at 828/258-3939, Ext. 226. In any future correspondence concerning this
project, please reference our Log Number 4-2-08-078.
Sinc ely,
Brian P. Cole
Field Supervisor
cc:
Mr. Larry Thompson, Environmental Supervisor, North Carolina Department of Transportation,
716 West Main Street, Albemarle, NC 28001
Mr. Steve Lund, Asheville Regulatory Field Office, U.S. Army Corps of Engineers, 151 Patton
Avenue, Room 208, Asheville, NC 28801-5006
Ms. Marla J. Chambers, Western NCDOT Permit Coordinator, North Carolina Wildlife
Resources Commission, 12275 Swift Road, Oakboro, NC 28129 -