20120142_R-3421C Field Review Letter_20150408

Pat McCrory
Governor
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NCDENR
North Carolina Department of Environment antl Natural Resources
April 8, 2015
Donald R. van der Vaarl
Secrelary
MEMORANDUM
To: Art King, Division 8 Environmental Officer /
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From: David Wainwright, Division of Water Resources, Cenhal OfficeJ '
Subject: Field Review of R-3421C, Richmond County
Dear Art:
On March 26, 2015, I performed a field review with you and Ms. Liz Hair of the USACE in which we
visited several wetland and stream impact sites associated with TIP R-3421 C, I-73/I-74 improvements
from US 74 Rockingham/Hamlet Bypass to US 220 Ellerbe Bypass.
During the field review, the following observations were made:
Site 3— One of the large stonnwater basins appeared to have been recently expanded. The side
slopes of the expansion area was not malted or seeded. In order to protect the integrity of the side
slopes and prevent erosion, it is highly recommended that these slopes be stabilized. It was also
noted that one of the lower basins was full of water to the extent that the bafFles were underwater
yet no water was draining out of the basin. As you know, the basins are designed such that the
baffles slow the incoming water, allowing sediment to settle out before being discharged. If the
bafFles are covered, then the basin will likely have water passing over the rop of the baffle,
thereby defeating the purpose of the basin. This situation needs to be corrected as if it continues
excessively turbid water may be discharged, leading to a potential water quality violation.
Several of the tiered stormwater basins were starting to accumulate a fair amount of sediment.
These basins should be inspected regularly to ensure that a buildup of sediment does not impede
the proper operation and intent of these basins and accumulated sediment removed as necessa�y.
Any baffles that are not properly set should be repaired as well.
A sediment loss had also occurred at this site as a result of a stormwater basin overflow. The
sediment had been cleaned by hand and looked fairly good. Addilional stornnvater basins h�d
bzen added and an expansion of one had taken place to prevent future overflows and sediment
losses.
1617 Mail Service Center, Raleigh, Nodh Carolina 27699-1617
Phone�.919-807-630011ntemef. www.ncdenr.gov
An Equal Oppotlunity 1 Af(umalive Aclion Fmployer

• Site 27 — The sediment control fence at the toe of slope near the culvert is excessively full of rock
and sediment, causing the fence to bulge and sag. The excess sediment and rock needs to be
removed and the fence restored (see picture below).
The NCDWR has concerns with the toe of slope in this area and how it ties into the stream bank
and the culvert. The fill slope in this area consists of riprap, and appears rather unstable. Rip rap
that had rolled down the slope and near the stream was observed. The NCDWR would like to see
this area redesigned such that Nie tie in is more stable and less likely to cause problems in the
future (see picture below).
The right bank of the stream near the headwall has been stabilized with rip rap and coir fiber
matting. The area under the matting has eroded, creating a very steep bank and therefore the coir
fiber matting is no longer serving its intended purpose. This bank will very likely continue to
erode if left alone. The matting should be removed and the bank repaired and restabilized. The
NCDOT will need to ensure that wha[ever means are used to stabilize the bank will be sufficient
to prevent erosion, oYherwise the same situation is Iikely to occur again (see picture below).
The culvert at this site was perched at the inlet and a concrete sill had been poured. In an attempt
to try and get sediment to settle in the culvert, rip rap has been placed instream on the
downstream side of the outlet. There was discussion during the field review about perhaps finding
another, more appropriate way, to slow the flow in order to help retain sediment in the culvert.
One such method, and preferable to riprap in the stream, would be to construct a log sill.
Appropriately designed, it would be stable, allow sediment to collect in the stream, have a smaller
instrcam footprint than riprap, and would look more natural.
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Site 27 — Condition of the sediment and erosion
control fence and the unstable riprap at the toe of
slope/bank of stream.
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Site 27 — SUeam bank has eroded under the coir fiber
malting near the inlet of the culvert and should be
restabilized.
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Site 27 — Outlet of culvert with riprap in stream.

• Site 7— There have been several sediment releases in to the wetland at this site since the project
started. During discussions, NCDOT felt they had identified the issues which led to these releases
and had taken proper steps to prevent them occurring again in the future. The sediment in the
wetland may need to be cleaned up by hand more, as a fair amount was still evident in the
wetland.
I looked at several of the stormwater basins for this area and they appeared to be in good order.
Please be mindful to perfonn routine inspections, clean them out, and repair these basins as
necessary.
I appreciate you taking the time to review the project with me and discussing the status and issues
currently associated with these sites. Should you have any questions or need anything further, please do
not hesitate to contact me at [phone] or [e-mail].