18050_CENCO_O_20190304

GE PHYSICAL
March 4, 2019
John D. Reuscher, PG, RSM
Hart & Hickman, PC
2923 South Tryon Street, Suite 100
Charlotte, NC 28203
Via email to: [e-mail]
SUBJECT: Cenco Brownfield Site Assessment— 609 Melynda Road, Charlotte, North Carolina
EM31 & GPR Testing Results for Trench Detection, GSI Project No. 2019-11
Dear Mr. Reuscher:
On February 28, 2019, Geophysical Survey Investigations, PLLC performed electromagnetic
(EM) ground conductivity and ground penetrating radar (GPR) testing across the central portion
of a covered trench area to determine if either geophysical methods could accurately
detect/delineate the individual trenches. The subject trench area is located on the Cenco property
at 609 Melynda Road in Charlotte, North Carolina. Hart & Hickman representative, Mr. John
Reuscher, PG was on site during the geophysical testing and identified the central portion of the
trench area where seven, east -west trending trenches are present.
Geophysical Testing Results
A Geonics EM31 terrain conductivity meter and a GSSI-3000 GPR unit equipment with a 400
MHz antenna, which had maximum investigating depth of 18 feet and 6 feet, respectively, were
used to perform the trench detection testing.
An EM31 conductivity reconnaissance was performed along south to north traverse lines
(perpendicular to the trenches axes) across the central portion of the trench area. Background
ground conductivity values (outside of the trench area) ranged from 8 to 10 millimhos/meter
(mmhos/m). The central portion of the trench area recorded slightly higher apparent conductivity
values of 10 to 12 mmhos/m. Conductivity spikes, which could indicate a an individual trench
location were not recorded and consequently the subtle rise in conductivity values failed to
identify the individual trenches.
GPR data were recorded along a south to north traverse line located in the central part of the
trench area and is presented in the attached Figure 1. Similar to the EM31 conductivity results,
the GPR recon recorded subtle changes in reflection character and failed to identify/delineate the
trenches. Hand auger sampling was performed at line distance 6 feet and 36 feet in which subtle
changes in GPR reflections were recorded. Sampling results down to a depth of 3.25 feet at both
locations did not encounter trench filled material. Furthermore, the GPR data failed to detect the
known trench that is located near line distance 29 feet.
4 Willimantic Drive Greensboro, NC 27455 Office Tel: [phone]
Mark J. Denil, PG [e-mail] Cell Tel: [phone]

The EM31 and GPR testing are considered to be the best two geophysical methods for trench
detection at this site. Because both methods were unsuccessful, we do not recommend any
further geophysical testing for trench detection at this site.
Sincerely,
Geophysical Survey Investigations, PLLC
Mark J. Denil, P.G.
Project Manager
Attached: Figure 1, GPR Image Across Trench Area
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GPR IMAGE ACROSS TRENCH AREA
HAND AUGER DISTANCE (feet)
SAMPLING 10 20
NORTH
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HAND AUGER
30 SAMPLING 40
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LOCATION OF
KNOWN TRENCH
The GPR image shown above was acquired across the central portion of the covered -trench area where seven east -west trending sludge trenches are present.
Hand auger sampling was performed at line distance 6 feet and at 36 feet where subtle GPR anomalies (changes in reflection character) were recorded. The
sampling at both locations were performed to a depth of approximately 3.25 feet and did not encounter trench -related material, suggesting that the GPR scanning
was not detecting the trenches. In addition, the GPR testing did not detect the location of the known trench that was marked at line distance 29 feet. Consequently,
the GPR scanning to located the trenches was terminated at this site.