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Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E. Director
Division of Water Quality
June 17, 2005
MEMORANDUM
TO: Colista Freeman, P.E., NCDOT Project Development & Environmental Analysis
r, 01
FROM: V Christina Breen, NC Division of Water Quality
SUBJECT: Scoping Review of NCDOT's proposed bridge replacement projects: B-4672, and
B-4673
In reply to your correspondence dated May 20, 2005 (received May 31, 2005) in which you requested
comments for the referenced projects, the NC Division of Water Quality has the following comments:
L Proiect-Specific Comments
B-4672 Bridke over Nahunta Swamp, Wayne Co.
Nahunta Swamp are class C, Sw, NSW waters of the State. Nahunta Swamp is on the 303(d) list for
impaired use for aquatic life due to impaired biological mtegr4t?. DWQ is very concerned with
sedimentation and erosion impacts that could result from this p:f,'Q ect. DWQ recommends that the most
protective sedimentation and erosion control BMPs be implemr ed to reduce the risk of nutrient runoff
to Nahunta Swamp. DWQ requests that road design plans provi4 treatment of the storm water runoff
through best management practices as detailed in Best Management Practices for the Protection of
Surface Waters. Refer to 15A NCAC 2B .0224(2) and 15A NCAC 2H. 1006. This project is within the
Neuse River Basin. Riparian buffer impacts should be avoided and minimized to the greatest extent
possible. Refer to 15A NCAC 2B .0233 for a table of allowable uses.
B-4673 Bridize over Walnut Creek (Lake Wackena), Wayne Co.
Walnut Creek (Lake Wackena) are class C, NSW waters of the State. Walnut Creek (Lake Wackena) is
on the 303(d) list for impaired use for aquatic life due to impaired biological integrity. DWQ is very
concerned with sedimentation and erosion impacts that could result from this project. DWQ recommends
that the most protective sedimentation and erosion control BMPs be implemented to reduce the risk of
nutrient runoff to Walnut Creek (Lake Wackena). DWQ requests that road design plans provide treatment
of the storm water runoff through best management practices as detailed in Best Management Practices
for the Protection of Surface Waters. Refer to 15A NCAC 2B .0224(2) and 15A NCAC 2H. 1006. This
project is within the Neuse River Basin. Riparian buffer impacts should be avoided and minimized to the
greatest extent possible. Refer to 15A NCAC 2B .0233 for a table of allowable`uses.
H. General Comments Reyardinz Bridke. Replacement Proiects
1. If corrugated metal pipe arches, reinforced concrete pipes, or concrete box culverts are used to replace
the bridge, then DWQ recommends the use of Nationwide Permit No. 14 rather than Nationwide
Permit 23.
2. If the old bridge is removed, no discharge of bridge material into surface waters is preferred. Strict
adherence the Corps of Engineers guidelines for bridge demolition will be a condition of the 401
Water Quality Certification.
Nom` Carolina
Qt!!rQ!!1,
Transportation 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: hftp://h2o.enr.state.nc.us/ncwetlands

3. DWQ prefers 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.
4. Bridge deck drains should not discharge directly into the stream;. stormwater should be directed
across the bridge and pre-treated through site-appropriate means (grassed swales, pre-formed scour
holes, vegetated buffers, etc.) before entering the stream. Please refer to NCDOT Best Management
Practices for the Protection of Surface Waters.
Live concrete should not be allowed to contact the water in or entering into the stream. Concrete is
mostly made up of lime (calcium carbonate) and when in a dry or wet state (not hardened) calcium
carbonate is very soluble in water and has a pH of approximately 12. In an unhardened state concrete
or cement will change the pH of fresh water to very basic and will cause fish and other
macroinvertebrate kills.
6. If possible, bridge supports (bents) should not be placed ih the stream.
7. If temporary access roads or detours are constructed, they stould be removed back to original ground
elevations immediately upon the completion of the project. bisturbed areas should be seeded or
mulched to stabilize the soil and native tree species should b( planted with a spacing of not more than
10'x10'. If possible, when using temporary 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 re-vegetate naturally and minimizes disturbed soil.
8. A clear bank (rip rap-free) area of at least 10 feet should remain on each side of the steam underneath
the bridge.
9. Sedimentation and erosion control measures sufficient to protect water resources must be
implemented prior to any ground disturbing activities. Structures should be maintained regularly,
especially following rainfall events.
10. Bare soil should be stabilized through vegetation or other means as quickly as feasible to prevent
sedimentation of water resources.
11. 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.
12. 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. This
equipment should be inspected daily and maintained to prevent contamination of surface waters from
leaking fuels, lubricants, hydraulic fluids, or other toxic materials.
III. General Comments if Replacing the Bridge with a Culvert
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 (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 may be accomplished by utilizing
sills on the upstream end to restrict or divert flow to the base flow barrel(s). Sufficient wateK- depth
should be provided in the base flow barrel 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, the 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 should 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.
laced in the streambed in a manner that
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4. Riprap should not be placed in the active thalweg channel" Ar
precludes aquatic life passage. Bioengineering boulders otructures 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 grass and planted with native tree species. Tall fescue should not be used in
riparian areas. If the area that is reclaimed was previously wetlands, NCDOT should restore the area to
wetlands. If successful, the site may be used as wetland mitigation for the subject project or other
projects in the watershed.
Thank you for requesting our input at this time. The DOT is reminded that issuance of a 401 Water
Quality Certification requires that appropriate measures be instituted to ensure that water quality
standards are met and designated uses are not degraded or lost. If you have any questions or require
additional information, please contact Christina Breen at [phone].
cc: Eric Alsmeyer, USACE Raleigh Field Office
Chris Militscher, USEPA
Travis Wilson, NCWRC
Gary Jordan, USFWS
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