RA-855_5746_CA_MRP_20130501_Terraquest

Monitoring Wells
Prior to sampling, Terraquest personnel purged each monitoring well of approximately three
well volumes of water using a new polyethylene bailer. The same bailers were then used to
retrieve a representative sample and place it into the appropriate laboratory-prepared
containers.
All of the collected groundwater samples were placed in laboratory-prepared sample
containers, labeled, packed in ice, and shipped to a North Carolina-certified laboratory for
analysis prior to the expiration of the analytical method's hold time. The groundwater samples
were analyzed using EPA Method 6200B. Monitoring well locations are indicated on Figure 3
and monitoring well construction information is listed in Table 4.
Water Supply Wells
On February 18, 2013, Terraquest personnel collected groundwater samples from water supply
wells WSW1, WSWS, and WSW6. Prior to collecting a water supply well groundwater sample,
the water was allowed to run for approximately 10 minutes to purge any stagnant water in the
well's bladder tank. After 10 minutes, Terraquest personnel, donning a new pair of nitrile
gloves, reduced the water flow and collected a water sample in the appropriate laboratory­
prepared containers. Samples were labeled and packed on ice pending transit to an NC­
licensed laboratory for analysis per EPA Methods 6200B. Water supply well information is
contained in Table 3. Well locations are referenced on Figure 2.
Analytical Results
Groundwater analytical results of the collected groundwater samples from monitoring wells
MW1 and MW2 reveal the continued presence of petroleum-type contaminant concentrations
exceeding the 2L Standard. In general, contaminant concentrations in monitoring well MW1
Groundwater Monitoring Report
Sampling Date: 2/27 /13
Report Prepared: 5/1/13 3
NC-DENR State Lead
County Line Grill
Roxboro, NC
have remained relatively the same, while contaminant concentrations in monitoring well MW2
have decreased. These analytical results show groundwater quality prior to the MMPE event
conducted in March.
Groundwater analytical results of collected groundwater samples from water supply well
WSWl reveals detections of benzene, MTBE, and 1,2,4-Trimethylbenzene at concentrations less
than 2L Standards. Analytical results for water supply well WSW5 revealed a detection of an
MTBE concentration less than the 2L Standard. No petroleum-type contaminant
concentrations were reported in the water supply well WSW6 groundwater sample. A
summary of groundwater analytical results is contained in Table 5. Groundwater analytical
results are also depicted on Figure 4. The full analytical report is contained in Appendix B.
4.0 WATER SUPPLY WELL ABANDONMENT
On January 31, 2013, and February 4, 2013, at the request of NCDENR-DWM personnel,
Piedmont Industrial Services, Inc. abandoned water supply wells WSW2, WSW3, WSW4, and
WSW7. Water supply well WSW2 was 144 feet in total depth, WSW3 was 160 feet, WSW4 was
22 feet, and WSW7 was 39 feet. Well abandonment records for each well are contained in
Appendix C.
5.0 CONCLUSIONS AND RECOMMENDATIONS
Due to the presence contaminant concentrations in excess of 2L Standards in monitoring wells
MWl and MW2 and the presence of sole-source water supply wells within 1,000 feet of the
site, a risk ranking of "high" is mandated for the site. Terraquest recommends the completion
of a Comprehensive Site Assessment to define the extents of soil and groundwater impact.
Along with the completion of a CSA, Terraquest also recommends continued monitoring and
MMPE events.
Groundwater Monitoring Report Sampling Date: 2/27 /13
Report Prepared: 5/1/13 4
NC-DENR State Lead
County Line Grill
Roxboro, NC