20161221 Ver 1_R-5311A NOV Response June 2018_20180612

STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
ROY COOPER
GOVERNOR
June 11, 2018
Amy Chapman
Transportation Permitting Supervisor
1617 MSC
Raleigh, 27699-1617
JAMES H. TROGDON, III
SECRETARY
Subject: NCDOT Response to Notice of Violation (NOV-2018-PC-0186)
Project R-5311A - Hertford County
Dear Ms. Chapman,
In response to the Division of Water Resource issuance of NOV-2018-PC-0186, the
provided response details sediment and erosion control efforts associated with the
R-5311A Modlin Road Borrow Pit and revised procedures following the NOV issuance.
The Modlin Road Borrow site was reviewed and approved through NCDOT's
reclamation plan procedures for borrow and waste sites. This included an investigation
and report from the State Historic Preservation Office, protected species review, and
jurisdictional wetland/stream delineation. The review and report was conducted by
Southern Environmental Group, Inc., which concluded and verified jurisdictional
wetlands within the borrow pit project area and one channelized tributary approximately
600 ft. to the southwest of the proposed pit boundary. This tributary drains to a
confluence with Horse Swamp 2.2 miles downstream. Horse Swamp carries the DWR
classification of C,NSW which extends down the drainage way to Montgomery Mill Pond
and Bear Swamp, before entering Ahoskie Creek, approximately 6 miles from the borrow
site project area.
The contractor, W. C. English Incorporated (English) had the borrow site designed and
approved by Cape Fear Engineering, which incorporated the appropriate erosion control
measures for the site development, along with calculated stilling/settling basins for the
proposed dewatering operation. The plan and measures were installed and maintained by
the contractor. A copy of the plan has been provided with this letter for reference. Field
inspectors reviewed the site weekly to insure compliance with the reclamation plan
design. During the dewatering operation of the borrow pit, a procedure was established by
NCDOT and English to monitor turbidity levels at the point of discharge into the
113 Airport Dr., Suite 100, Edenton, NC 27932 — Phone: [phone] Fax: [phone]

jurisdictional tributary and the perimeter ditch. This was done by both turbidity meter and
visual observation. During pumping operation, these readings were taken 4 times daily. If
any readings exceeded the 50 NTU limit, then the pumping operation was shut down.
After several weeks of the initial pumping operation beginning, it was decided that an
additional sediment basin beyond what was designed would be helpful in providing
holding time,for the dewatering operation. This basin (300'X50') was installed and
utilized during pumping. In addition to the extra sediment basin, English sent a sample of
the borrow pit water to a supplier of floc logs, in an effort to place site specific floc logs
at the discharge point of the stilling basin, which would provide another layer of sediment
treatment. Beyond the point of discharge for the stilling basin, the water travelled
approximately 800 ft. through a pine plantation, before entering the perimeter ditch,
where the last layer of treatment was the placement of wattles, to slow down the flow and
provide extra settling time.
On the week of May 14th, NCDOT was following the established procedures for
the borrow pit dewatering operation. Rainfall recorded on the project for the week, was
0.4 inches on 5/15/18 and 1.0 inch recorded 5/16/18 (rainfall occurred during evening of
5/15 and early morning of 5/16, prior to 6:OOam). Below is a summary of the week's
events recorded by the NCDOT Resident Engineer Michael Hill:
1. On Monday, 5/14/18, the contractor pumped water all day and turbidity levels did not
exceed 50 NTU's before the contractor left. Water was allowed to pump during the
evening hours and through the night.
2. On Tuesday morning, 5/15/18, turbidity level was slightly above 50 NTU's (56 NTU's),
so the pump was cut of£ The turbidity levels in the stream dropped and the pumps were
cut back on at some point.
3. On Tuesday, the superintendent sent his men home for the week, so NCDOT's lead
project inspector did not go to the project on Wednesday or Thursday.
4. On Wednesday morning, 5/16/18, the turbidity level was recorded at 68 NTU's. The
pump was cut off by the contractor. At around 3:30 on Wednesday afternoon, the pump
was off and the superintendent found the turbidity level in the stream to be 41
NTU's. The superintendent cut the pump on and let it pump through the evening and
night hours.
5. On Thursday morning, 5/17/18, at around 6:30 AM, the superintendent saw that the
turbidity level was very high. He cut the pump off. He then checked the turbidity level
and found it to be 161 NTU's. Due to the contractor sending his men home earlier in the
week and no work taking place on-site, NCDOT's inspector was not on-site. The
Department was not notiiied by the contractor of the 161 NTU reading.
6. Approximately 8 to 9 hours later in the day on Thursday (5/17), Garcy Ward with DWR
discovered the high turbidity levels. The pumps had remained shut off from the earlier
6:30am reading the contractor had recorded. Garcy Ward contacted NCDOT Roadside
Environmental Field Operations Engineer Andy Blankenship. Andy Blankenship
contacted Michael Hill around 3:30 PM on Thursday to notify the Resident Engineer of
the problem.
The following day on OS/18/18, NCDOT staff and DWR revisited the site to get
additional NTU readings of the perimeter ditch and downstream tributary. Those readings
well exceeded the 50 NTU requirements and are referenced in the NOV notice.
Immediately following the DWR site visit on Friday the 18th, the Resident Engineer
113 Airport Dr., Suite 100, Edenton, NC 27932 — Phone: [phone] Fax: [phone]

notified English that the dewatering operation of Modlin Pit had to cease until a new
method of sediment removal was established for the dewatering operation.
Since this event, English consulted on various methods of sediment removal for
dewatering operations of borrow pits. It was determined that a filter sock pipe drain
method would be installed. This method trenches in a perforated filter sock pipe around
the perimeter of the borrow pit. A pump system attached to the filter sock pipe can then
draw the water from inside the pit, through the ground and into the filter sock pipe. This
system was installed by the contractor at a cost of around $70,000 and is currently in
operation. The contractor has revised the monitoring protocol by adding additional
readings to include one every 2 hours, if the NTU reading exceeds 40. Any reading above
50 NTU's is to be reported immediately to NCDOT Resident Engineer staff,
Environmental Supervisor, and Roadside Environmental Field Operations Engineer.
NCDOT is regretful this incident occurred and will continue to monitor the
borrow site closely. We have impressed upon the contractor that NCDOT values our
working relationship with the regulatory community and intend to work together, moving
projects forward in compliance with the environmental permit conditions. I have included
the erosion control plans for the Modlin Rd. borrow site, along with a USGS topographic
location map, and aerial illustrations of the site.
If you have questions or would like to discuss further, please feel free to contact
either of us at [phone].
Sincerely,
J ry D. � nnings, PE
Di�isio�i En�i�er
�/c- /��-
Clay 1is
Division Environmental Officer
Attachments
CC: Tim Little, PE, NCDOT, Chief Engineer
Philip S. Harris, III, P.E., CPM, NCDOT
Michael Hill, P.E., NCDOT, Resident Engineer
Andy Blankenship, P.E., NCDOT Roadside Environmental
Kyle Barnes, US Army Corp of Engineers, Washington District Office
Samir Dumpor, DEMLR, Washington Regional Office
Chris Rivenbark, NCDOT
113 Airport Dr., Suite 100, Edenton, NC 27932 — Phone: [phone] Fax: [phone]