20070597 Ver 1_Other Agency Comments_20070507

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® North Carolina Wildlife Resources Commission
Richard B. Hamilton, Executive Director
MEMORANDUM
TO: Sterling Baker, Division Maintenance Engineer
NCDOT, Division 1
FROM: Travis Wilson, Highway Project Coordinator ~ _ ~ / ~/~- J
Habitat Conservation Program C~ ~/
DATE: Apri130, 2007
SUBJECT: NCDOT Bridge Replacements in Ocracoke, Hyde County
Biologists with the N. C. Wildlife Resources Commission (NCWRC) have reviewed the
information provided and have the following preliminary comments on the subject project. Our
comments are provided in accordance with provisions of the National Environmental Policy Act
(42 U.S.C. 4332(2)(c)) and the Fish and Wildlife Coordination Act (48 Stat. 401, as amended; 16
U.S.C. 661-667d).
Our standard recommendations for bridge replacement projects of this scope are as
follows:
1. We generally prefer spanning structures. Spanning structures usually do not require
work within the stream and do not require stream channel realignment. The horizontal
and vertical clearances provided by bridges allows for human and wildlife passage
beneath the structure, does not block fish passage, and does not block navigation by
canoeists and boaters.
2. Bridge deck drains should not discharge directly into the stream.
3. Live concrete should not be allowed to contact the water in or entering into the stream.
4. If possible, bridge supports (bents) should not be placed in the stream.
5. If temporary access roads or detours are constructed, they should be removed back to
original ground elevations immediately upon the completion of the project. Disturbed
areas should be stabilized with native vegetation. If possible, when using temporary

Bridge Memo 2 Apri130, 2007
structures the area should be cleared but not grubbed. Clearing the area with chain
saws, mowers, bush-hogs, or other mechanized equipment and leaving the stumps and
root mat intact, allows the area to revegetate naturally and minimizes disturbed soil.
6. A clear bank (riprap free) area of at least 10 feet should remain on each side of the
steam underneath the bridge.
7. In trout waters, the N.C. Wildlife Resources Commission reviews all U.S. Army
Corps of Engineers nationwide and general `404' permits. We have the option of
requesting additional measures to protect trout and trout habitat and we can
recommend that the project require an individual `404' permit.
8. In streams that contain threatened or endangered species, NCDOT biologist Mr.
Logan Williams should be notified. Special measures to protect these sensitive species
maybe required. NCDOT should also contact the U.S. Fish and Wildlife Service for
information on requirements of the Endangered Species Act as it relates to the project.
9. In streams that are used by anadromous fish, the NCDOT official policy entitled
"Stream Crossing Guidelines for Anadromous Fish Passage (May 12, 1997)" should
be followed.
10. In areas with significant fisheries for sunfish, seasonal exclusions may also be
recommended.
11. Sedimentation and erosion control measures sufficient to protect aquatic resources
must be implemented prior to any ground disturbing activities. Structures should be
maintained regularly, especially following rainfall events.
12. Temporary or permanent herbaceous vegetation should be planted on all bare soil
within 15 days of ground disturbing activities to provide long-term erosion control.
13. All work in or adjacent to stream waters should be conducted in a dry work area.
Sandbags, rock berms, cofferdams, or other diversion structures should be used
where possible to prevent excavation in flowing water.
14. Heavy equipment should be operated from the bank rather than in stream channels in
order to minimize sedimentation and reduce the likelihood of introducing other
pollutants into streams.
15. Only clean, sediment-free rock should be used as temporary fill (causeways), and
should be removed without excessive disturbance of the natural stream bottom when
construction is completed.
16. During subsurface investigations, equipment should be inspected daily and
maintained to prevent contamination of surface waters from leaking fuels, lubricants,
hydraulic fluids, or other toxic materials.
If corrugated metal pipe arches, reinforced concrete pipes, or concrete box culverts are
used:
1. The culvert must be designed to allow for aquatic life and fish passage. Generally, the
culvert or pipe invert should be buried at least 1 foot below the natural streambed

Bridge Memo
Apri130, 2007
(measured from the natural thalweg depth). If multiple barrels are required, barrels
other than the base flow barrel(s) should be placed on or near stream bankfull or
floodplain bench elevation (similar to Lyonsfield design). These should be
reconnected to floodplain benches as appropriate. This maybe accomplished by
utilizing sills on the upstream and downstream ends to restrict or divert flow to the
base flow barrel(s). Silled barrels should be filled with sediment so as not to cause
noxious or mosquito breeding conditions. Sufficient water depth should be provided
in the base flow barrel(s) during low flows to accommodate fish movement. If
culverts are longer than 40-50 linear feet, alternating or notched baffles should be
installed in a manner that mimics existing stream pattern. This should enhance
aquatic life passage: 1) by depositing sediments in the barrel, 2) by maintaining
channel depth and flow regimes, and 3) by providing resting places for fish and other
aquatic organisms. In essence, base flow barrel(s) should provide a continuum of
water depth and channel width without substantial modifications of velocity.
2. If multiple pipes or cells are used, at least one pipe or box should be designed to
remain dry during normal flows to allow for wildlife passage.
3. Culverts or pipes should be situated along the existing channel alignment whenever
possible to avoid channel realignment. Widening the stream channel must be avoided.
Stream channel widening at the inlet or outlet end of structures typically decreases
water velocity causing sediment deposition that requires increased maintenance and
disrupts aquatic life passage.
4. Riprap should not be placed in the active thalweg channel or placed in the streambed
in a manner that precludes aquatic life passage. Bioengineering boulders or structures
should be professionally designed, sized, and installed.
In most cases, we prefer the replacement of the existing structure at the same location
with road closure. If road closure is not feasible, a temporary detour should be designed and
located to avoid wetland impacts, minimize the need for clearing and to avoid destabilizing
stream banks. If the structure will be on a new alignment, the old structure should be removed
and the approach fills removed from the 100-year floodplain. Approach fills should be removed
down to the natural ground elevation. The area should be stabilized with native species. If the
area reclaimed was previously wetlands, NCDOT should restore the area to wetlands. If
successful, the site maybe utilized as mitigation for the subject project or other projects in the
watershed.
Project specific comments:
NCDOT is proposing to replace seven bridge structures located on NC 12 on
Ocracoke Island simultaneously between January 2 and March 15, 2008. All structures will
be replaced in place while utilizing a 3.2 mile detour route along the beach. The project area
contains habitat for multiple priority species associated with beach and dune habitats, as
identified in the North Carolina Wildlife Action Plan (North Carolina Wildlife Resources
Commission. 2005. North Carolina Wildlife Action Plan. Raleigh, NC).
NCDOT has minimized potential impacts to these species by proposing a condensed
construction timeframe to occur outside of the nesting season for both colonial water birds
and sea turtles. However due to the potential for this project to continue beyond the goal of a
March 15t'' completion date, we are requesting an April 1 to November 15 moratorium for

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Bridge Memo 4 Apri130, 2007
project related construction activities occurring on the ocean side of NC 12. Furthermore, the
temporary beach detour should be restored to its pre-project state including smoothing any
vehicle ruts that may entrap or impede hatchling sea turtles prior to April 1.
If you need further assistance or information on NCWRC concerns regarding bridge
replacements, please contact me at [phone]. Thank you for the opportunity to review
and comment on these projects.
Cc:
Gary Jordan, USFWS
Bill Biddlecome, USACE
Cathy Brittingham, DCM
David Wainwright, DWQ