20060331 Ver 1_Emails_20101103

S
STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTA710N
BEVERLY EAVES PERDUE
GOVERNOR
MEMORANDUM TO:
FROM:
STATE PROJECT:
COUNTY:
DESCRIPTION:
SUBJECT:
EUGENE A. CONTI, JR.
SECRETARY
November 3, 2010
Jeff Loilin, P.E.
..Resident Engineer
01 L. Pillip uk, L.G., P.E.
Western Region Geotechnical Manager
39460 (34480.3.GV1)
Randolph
US -311 Bypass (Future I -74) From North of SR -1929 (Spencer
Road) to US -220:
Farlow Pond Sediment Investigation in Randolph County, NC
On October 25, 2010, the Geotechnical Engineering Unit completed a pond sediment
investigation at property address 3083 Thompson Heath Road, Sophia, NC for the above
referenced project. This memo presents our findings and observations.
BACKGROUND INFORMATION
We understand that the owner of the referenced property has claimed that construction activities
related to the project have resulted in sediment deposits within the pond located at the property.
Subsequently, the Geotechnical Engineering Unit was contacted to conduct sediment sampling of
the pond bottom.
In early June, significant rainfall events occurred in the area of the project that resulted in failure
of the project erosion and sediment control devices on two separate occasions. The devices are
located on the west side of the project roadway grade between the project's crossings of Plainfield
Road and existing US Highway 311. This portion of the project crosses the eastern drainage area
of the pond approximately 10,000 feet upstream of the headwaters of the pond. A western
drainage area also serves the subject pond, but is separated from the project by a ridge.
Just days after failure of the erosion and sediment control devices, representatives of the NCDOT,
the project Contractor, the NCDENR, and the US Army Corps of Engineers evaluated the extent
of the sediment loss from the project by tracing the eastern drainage feature from the project
downstream. During that field inspection, it was determined that the end of the significant
sedimentation (sediment which had to be retrieved and/or cleaned fiom the feature by hand)
resulting from the project occurred approximately 900 feet downstream in the eastern drainage
MAILING ADDRESS: TELEPHONE: [phone] LOCATION:
NCDOT WESTERN REGIONAL WESTERN REGIONAL
GEOTECHNICAL OFFICE FAX: [phone] GEOTECHNICAL OFFICE
COURIER: 0537 -01 5253 Z MAX DOEXEVAAD
WEDSITE. WWW.00N.D0T.STATE.NC.US HARRIseum, NC 28075

Jeff Loflin, P.E.
November 3, 2010
Page 2
feature. The project Contractor subsequently removed the sediment from the feature to the
satisfaction of the NCDOT, the NCDENR, and the US Army Corps of Engineers.
SCOPE OF WORK
Our investigation included general field observations of the existing pond conditions and the
collection of eight (8) bottom -of -pond sediment specimens. Representatives of the project
Contractor and the NCDOT and the property owner determined the sampling locations. The
samples were collected by inserting 2 -inch diameter clear PVC pipe into the pond bottom to
retrieve a plug of pond sediment. The PVC pipe was capped at each end to preserve the samples.
GPS coordinates of each test location were collected during sampling. Specimens were returned
to our office for further evaluation.
FINDINGS
At our office, each of the sediment samples was visually evaluated to determine distinct breaks in
sediment layers based upon apparent grain size and/or color. In this instance, color was the major
differentiating factor between what was determined to be recent (orange- brown) and historic
(gray - black) sediment in the samples. Only minor differences, if any, in grain size could be
visually discerned between recent and historic sediment. The non - primary (recent) sediment
thickness at each sample location is shown in the table below and on the attached plan view.
Sample Location
Non - Primary Serd1ment
Thickness inches
1
0.25
2
0.40
3
0.30
4
0.30
5
0.15
6
0.00
7
0.00
8
0.00
In general, sedimentation from a single -point source such as the subject project generally occurs
quickly for the larger grain sizes in the sediment. However, the smaller silt grains in the sediment
remain suspended in the water for greater distances downstream. Given the facts that
insignificant sediments existed beyond 900 feet downstream of the prt ject as determined by the
environmental agencies and that the subject pond is located an additional 9,000 feet downstream
from the end of significant project sedimentation, it is highly unlikely that the non - primary
(recent) sediments observed in the samples collected from the subject pond result from
construction activities related to the project.
Please call John L. Pilipchuk, L.G., P.E. or Dean Hardister, P.E. at (704)455 -8902 if there are any
questions concerning this memorandum.
JLP /DH
Attachment