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Home My WebLink AboutWS-4277_13937_CA_MRP_20180522 May 22, 2018 Ms. Linda Blalock NCDEQ, Division of Waste Management, UST Section 1646 Mail Service Center Raleigh, North Carolina 27699-1646 RE: Letter Report – Pleasant Hill Grocery 623 Austin Traphill Road Elkin, Wilkes County, North Carolina NCDEQ Incident No.: 13937 NCDEQ Contract No. N17006 ECS Project No. 49-6588 Dear Ms. Blalock: As authorized by your acceptance of ECS Southeast, LLP’s (ECS) Task Authorization Request No. 1 dated and approved March 27, 2018, ECS has prepared a Letter Report for the above referenced site. This report includes a description of the work performed, the results obtained, and our conclusions and recommendations. PROJECT UNDERSTANDING The subject site was occupied by the Pleasant Hill Grocery located at 623 Austin Traphill Road in Elkin, Wilkes County, North Carolina (Figures 1 and 2). The subject site consists of an approximate 2.6 acre parcel identified as Wilkes County Parcel Identification Number (PIN) 4941-47-1684. The facility ID number for the site is 00-0-0000035336. The site currently consists of an active gasoline station. On March 23, 1994, two 8,000-gallon gasoline underground storage tanks (USTs), dispensers, and product lines were removed from the site. Soil samples were collected from beneath the USTs, the dispensers, and the product lines. Laboratory analysis of the soil samples detected total petroleum hydrocarbons (TPH) above the North Carolina State Action level. On April 20, 1994, approximately sixty-six cubic yards of contaminated soil was remediated on- site. Groundwater was not encountered during the excavation. Confirmation soil samples collected from the excavation did not detect TPH above the North Carolina State Action Level. The soil was remediated by using the CleanSoil Process. After the soil was remediated, a confirmation soil sample was collected from the remediated soil. Laboratory analysis of the confirmation soil sample did not detect TPH above the North Carolina State Action Level. Further investigation by the North Carolina Department of Environmental Quality Winston-Salem Regional Office revealed two previously unknown USTs that have been out of use since the 1960s. The USTs on the site consisted of one 500-gallon UST and one 1,000-gallon UST. It is unknown if the USTs were removed. SOURCE: USGS TOPOGRAPHIC MAP THURMOND, NORTH CAROLINA QUADRANGLE, DATED 1971 FIGURE 1 SITE LOCATION MAP PLEASANT HILL GROCERY 623 AUSTIN TRAPHILL ROAD ELKIN, WILKES COUNTY, NC NCDEQ INCIDENT NO.: 13937 ECS PROJECT NO. 49-6588 SITE 2,000’ SOURCE: WILKES COUNTY GIS WEBSITE AERIAL PHOTOGRAPH, DATED 2014 FIGURE 2 AERIAL SITE MAP PLEASANT HILL GROCERY 623 AUSTIN TRAPHILL ROAD ELKIN, WILKES COUNTY, NC NCDEQ INCIDENT NO.: 13937 ECS PROJECT NO. 49-6588 APPROXIMATE SITE BOUNDARY  9 10 11 12 13 14 15      C   C C A 230’ 7011 Albert Pick Road Suite E., Greensboro, NC 27409 phone 336.334.7724, fax 803.802.2515 www.espassociates.com April 24, 2018 Ashley Barham ECS Carolinas, LLP 4811 Koger Boulevard Greensboro, NC 27407 Reference: REPORT ON GEOPHYSICAL SERVICES 623 Austin Traphill Road Elkin, North Carolina ESP Project No. EQ02.310 Dear Ms. Barham: ESP Associates, Inc. (ESP) is pleased to present this report to ECS Carolinas, LLP (ECS) on the geophysical services we provided for the referenced project. This work was performed under our subconsultant agreement dated September 11, 2014 and in accordance with our cost proposal to you dated March 22, 2018. The purpose of the work was to help identify possible underground storage tanks (USTs). 1.0 GEOPHYSICAL DATA COLLECTION On April 20, 2018, ESP performed geophysical studies at 623 Austin Traphill Road, Elkin, North Carolina. The work consisted of metal detection using a Geonics EM61 MK2 instrument and subsurface imaging using a Sensors and Software Noggin 250 Ground- Penetrating Radar (GPR) instrument. The limit of the study area was based on information provided by to us by ECS via email on March 22, 2018. The EM61 data were collected over the accessible areas of the site using a line spacing of approximately 3 feet. We used a Hemisphere XF101sub-meter differential GPS instrument (DGPS) connected to an Archer field computer to provide approximate locations of the EM61 data in real time. We collected representative GPR data over selected EM61 anomalies with responses significant enough to represent possible USTs. The DGPS instrument was also used to obtain the approximate location of site features that could affect the EM61 readings. Report on Geophysical Services ESP Project No. EQ02.310 623 Austin Traphill Rd., Elkin, North Carolina April 24, 2018 2 2.0 DATA ANALYSIS AND PRESENTATION The EM61 data were gridded and contoured to produce plan view contour maps of the early time gate response (Figure 1) and the differential response (Figure 2). The differential response is calculated by subtracting the response of the bottom coil from the response of the top coil of the EM61. Typically, the differential response diminishes the response from smaller, near- surface metallic objects, thus emphasizing the response from deeper and larger metallic objects. The approximate DGPS locations of observed site features were superimposed on the EM61 contour maps so that anomalies caused by site features such as metal objects on the ground surface could be recognized. 3.0 DISCUSSION OF RESULTS The EM61 differential contour plot indicated high amplitude responses (anomalies) that correspond to storm drains, the known USTs, and vehicles. We collected GPR data over the known USTs, over the areas that had been occupied by vehicles at the time of the EM61 data collection, and over one anomaly located to the southeast of the known USTs. Our on-site review of the GPR data indicated the location of five known USTs between the existing pump islands in the central portion of the site. The GPR data also indicated that the concrete slab over the known USTs is reinforced. The GPR data did not indicate abandoned USTs at the other locations. Three of the known USTs are approximately 8 feet diameter by 6 feet long, the fourth is approximately 8 feet diameter by 20 feet long, and the fifth is approximately 8 feet diameter by 10 feet long. All 5 USTs are buried about 3 feet below the ground surface. We outlined the area of the known USTs using pink marking paint (Photo C, Figure 3). 4.0 SUMMARY AND CONCLUSIONS Our review of the geophysical data collected for this project did not indicate the presence of abandoned USTs. Three of the known USTs are approximately 2,000 gallons in size, the fourth is approximately 8,000 gallons in size, and the fifth is approximately 4,000 gallons in size. All five known USTs are buried about 3 feet below the ground surface. We recommend that drilling and sampling be performed at least 2 feet outside of the area we marked indicating the approximate edges of the known USTs. 5.0 LIMITATIONS These services have been provided to ECS in accordance with generally accepted guidelines for performing geophysical surveys. It is recognized that the results of geophysical surveys Report on Geophysical Services ESP Project No. EQ02.310 623 Austin Traphill Rd., Elkin, North Carolina April 24, 2018 3 are non-unique and subject to interpretation. Further, the locations of data and features included in this report are approximate and were collected using a sub-meter DGPS instrument. ESP makes no guarantee as to the accuracy of these locations. Thank you for the opportunity to be of service to ECS on this project. Please contact us if you have any questions or need further information. Sincerely, ESP ASSOCIATES, Inc. Edward D. Billington, PG DMN/EDB Attachments: Figures 1 – 3 PROJECT NO. DATE BY SCALE ESP Associates, Inc. 7011 Albert Pick Rd., Suite E Greensboro, NC 27409 336.334.7724 www.espassociates.com EQ02.310 4/24/2018 DMN 623 AUSTIN TRAPHILL ROAD ELKIN, NORTH CAROLINA FIGURE 1 EM61 EARLY TIME GATE RESPONSE AS SHOWN Note: Locations of data and features are approximate and were collected using a sub-meter DGPS instrument. ESP make no guarantees as to the accuracy of these locations. Coordinates on the axes of the maps are approximate and provided for general reference only. APPROXIMATE NORTH Anomaly from AST Anomaly from large truck Anomaly from parked vehicles PROJECT NO. DATE BY SCALE ESP Associates, Inc. 7011 Albert Pick Rd., Suite E Greensboro, NC 27409 336.334.7724 www.espassociates.com EQ02.310 4/24/2018 DMN 623 AUSTIN TRAPHILL ROAD ELKIN, NORTH CAROLINA FIGURE 2 EM61 DIFFERENTIAL RESPONSE AS SHOWN Note: Locations of data and features are approximate and were collected using a sub-meter DGPS instrument. ESP make no guarantees as to the accuracy of these locations. Coordinates on the axes of the maps are approximate and provided for general reference only. APPROXIMATE NORTH Anomaly from large truck Anomaly from parked vehicles PROJECT NO. DATE BY SCALE ESP Associates, Inc. 7011 Albert Pick Rd., Suite E Greensboro, NC 27409 336.334.7724 www.espassociates.com EQ02.310 4/24/2018 DMN 623 AUSTIN TRAPHILL ROAD ELKIN, NORTH CAROLINA FIGURE 3 PHOTOS OF SITE NTS B. Photo from southeast side of site, looking northwest. A. Photo from northwest side of site, looking southeast. C. Photo of marked known USTs, looking east.