WS-48_30023_CA_MRP_20200903

Letter Report Superior Car Wash
Eden, Rockingham County, North Carolina NCDEQ Incident No.: 30023
ECS Project No.: 49:3623-C
1
September 3, 2020
Mr. Herbert Berger NCDEQ, Division of Waste Management, UST Section 1646 Mail Service Center
Raleigh, North Carolina 27699-1646
Reference: Letter Report Superior Car Wash
102 Boone Road
Eden, Rockingham County, North Carolina
NCDEQ Incident No. 30023 NCDEQ Contract No. N17006 ECS Project No. 49:3623-C
Dear Mr. Berger:
As authorized by your acceptance of ECS Southeast, LLP’s (ECS) Task Authorization Request No.
3 dated July 17, 2020; and ECS’ emailed change order dated November 21, 2019, 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 INFORMATION
The Superior Car Wash is located at 102 Boone Road in Eden, Rockingham County, North Carolina (Figures 1 and 2). Photographs of the site are attached. During limited site assessment
activities associated with highway improvements to NC Highway 700 and Bridge Number 75 crossing the Smith River, Solutions Industrial & Environmental Services, Inc., advanced seven soil borings and collected soil samples at the Rush Properties, LLC property located at 102 Boone
Road (i.e., Superior Car Wash site). Prior to the advancement of soil borings, a geophysical survey was conducted of the area. Two anomalies suspected to be underground storage tanks (USTs) were found in front of the building using an EM-61 ferrous metal locator. Analytical results
of soil samples collected showed total petroleum hydrocarbons (TPH) concentrations exceeding 10 milligrams per kilogram (mg/kg) in six of the seven soil samples collected. The highest TPH-Gasoline Range Organic (GRO) concentration was 4,700 mg/kg and TPH-Diesel Range Organics
(DRO) was 2,200 mg/kg in the sample collected from soil boring B2 near the suspected USTs. UST information is summarized in Table 1.
On March 3, 2010, Terraquest personnel submitted a UST-3 Notice of Intent form to the NCDWM-UST. Prior to removing the UST on March 16, 2010, the remaining product (approximately 252 gallons) in the UST was removed. During the removal of the 1,000-gallon gasoline UST, a second UST (550-gallon gasoline) was discovered. After the discovery of the UST, the remaining residual liquid (approximately 550 gallons) was removed.
Terraquest personnel inspected the USTs after removal. The USTs appeared to be in good
Letter Report Superior Car Wash
Eden, Rockingham County, North Carolina NCDEQ Incident No.: 30023
ECS Project No.: 49:3623-C
2
condition with moderate rust and pitting, but no visible holes. The USTs were then taken off-site and disposed by Zebra Environmental.
After the USTs were removed on March 16, 2010, soil samples were collected at locations prescribed by the NCDWM-UST for UST closure. The UST closure samples were submitted for
TPH analysis for low (5030) boiling point fuels. Analysis of the UST closure samples detected concentrations of petroleum-type contaminants above the then Action Limit of 10 mg/kg for GRO.
After the USTs were removed, Terraquest personnel supervised the excavation of approximately 18 tons of contaminated soil. The vertical depth of the excavation was approximately 9 feet below the ground surface (bgs). The soil was transported off-site and disposed by Zebra Environmental. Terraquest personnel collected one soil sample from the base of the excavation (BE). The sample was submitted for risk-based laboratory analysis per EPA Method 8260 and MADEP VPH. The analysis of the soil sample detected several targeted constituents exceeding their respective soil-to-groundwater Maximum Soil Contaminant Concentrations (MSCCs), but below the Residential MSCCs. Based on the analytical results from the soil sample collected from the base of the excavation,
Terraquest recommended that a Limited Site Assessment (LSA) should be conducted to determine if groundwater has been impacted and to formally establish a risk rank for the site.
It should be noted that the Terraquest report makes no mention of product lines or dispensers found or removed and no samples were associated with these features.
A second UST incident is located across (west) Boone Road from the Superior Car Wash site. This incident is a responsible party lead site and is known as the former Spray Exxon located at 103 Boone Road in Eden, Rockingham County, North Carolina (Incident No.13568). The site consists of an active automotive maintenance shop, which stores gasoline and diesel fuel for retail sale in four USTs. A 4,000-gallon diesel UST was removed by G & H Oil Equipment, Inc. of Greensboro, North Carolina in July 1990. The diesel UST was replaced with the existing 3,000-gallon diesel UST. Legacy Environmental Services, Inc. (Legacy) submitted an UST Closure Report in December 1998 describing the closure activities that occurred in 1990 as well as additional activities which occurred in 1998. Apex Environmental, Inc. previously completed a Corrective Action Plan, dated October 15, 2003 with respect to the release. Although the incident documented at the site is related to the removal of a diesel fuel UST, historically groundwater
contamination beneath the site reflects a release of gasoline. Therefore, Progress Environmental, Inc. (Progress) collected groundwater samples for analysis for gasoline related compounds. It was Progress’ understanding that there is also a documented petroleum UST release at 102
Boone Road located northeast of the Spray Exxon site (the Superior Car Wash site). On December 17, 2014, Progress sampled site monitoring wells MW-1, MW-2, MW-3, MW-4,
MW-5, MW-7, and MW-1D. Monitoring wells MW-1, MW-2, MW-3, MW-4, and MW-1D were installed to assess the Spray Exxon site. Note that monitoring well MW-6 contained approximately 0.03 feet of LNAPL and, therefore, was not sampled. Monitoring wells MW-5, MW-6, and MW-7 are located off-site across Boone Road to the east. Monitoring well MW-7 is located on the Superior Car Wash property and MW-6 is located further southeast on a different property. Monitoring well MW-7 is located between the UST system formerly located on the Superior Car
Letter Report Superior Car Wash
Eden, Rockingham County, North Carolina NCDEQ Incident No.: 30023
ECS Project No.: 49:3623-C
3
Wash site and monitoring well MW-6.
The consultant handling the Spray Exxon incident has concluded that the Light Non-Aqueous Phase Liquids (LNAPL) hydrocarbons observed in monitoring well MW-6 may have originated from the Superior Car Wash site.
On December 15, 2016, ECS gauged monitoring wells MW-6 and MW-7 for LNAPL. ECS personnel used an interface probe to measure the depth to water and LNAPL, if present. The
probe measured 0.15 feet of LNAPL in monitoring well MW-6 (depth to water level 18.35, depth to product 18.2) and 0.01 feet in monitoring well MW-7 (water level 17.30, product 17.29). ECS concluded that an investigation was needed to determine the extent of LNAPL associated with the release originating from the UST system located on the Superior Car Wash property. On December 18, 2017, four soil borings (SS-1 through SS-4) were drilled at the site in the vicinity of the former UST location and two Type II monitoring wells (MW-8 and MW-9) were installed on the site. The wells were installed to a depth of 25 feet bgs. The wells were constructed with 2-inch Schedule 40 PVC casing and screen. On December 19, 2017, ECS personnel collected samples from monitoring wells MW-7, MW-8, and MW-9. LNAPL was measured in monitoring well MW-6; therefore MW-6 was not sampled. Laboratory analysis detected several petroleum
compounds above the Soil-to-Groundwater MSCCs, but below the Residential MSCCs in all four soil samples (SS-1 through SS-4). In soil sample SS-4, C5-C8 Aliphatics, C9-C12 Aliphatics, and C9-C10 Aromatics were detected above the Residential MSCCs, but below the
Industrial/Commercial MSCCs. On February 5, 2018, ECS observed the installation of two Type II monitoring wells (MW-10 and
MW-11) on the adjoining property south of the site. Following installation, monitoring wells MW-6 through MW-11 were horizontally and vertically located using a common datum. Groundwater flow direction was determined to be to the south under a gradient of 1.84 ft/ft as calculated between monitoring wells MW-9 and MW-11. On February 6, 2018, ECS personnel collected groundwater samples from monitoring wells MW-10 and MW-11. Laboratory analysis detected concentrations of numerous targeted compounds that exceeded the respective NC2LGWQS in monitoring wells MW-7 through MW-11. Laboratory analysis of the sample obtained from monitoring well MW-11 detected concentrations of benzene above the respective GCL. Several other petroleum related hydrocarbons were detected in the samples above their laboratory reporting limits, but below their NC2LGWQS.
On February 26, 2019, ECS personnel mobilized to the site to collect groundwater samples from monitoring wells MW-6 through MW-11. Approximately 0.01 feet of LNAPL was detected in monitoring well MW-6; therefore, a sample was not collected from monitoring well MW-6.
Laboratory analysis detected concentrations of numerous targeted compounds that exceeded the NC2LGWQS in monitoring wells MW-7 through MW-11; however, the concentrations are below their respective GCLs. Several other petroleum related hydrocarbons were detected above their
laboratory reporting limits, but below their NC2LGWQS.
FIGURE 1USGS TOPOGRAPHIC MAP
SUPERIOR CAR WASH102 BOONE ROADEDEN, NORTH CAROLINANCDEQ INCIDENT No. 30023
ECS PROJECT No. 49:3623-C
SOURCE:
USGS TOPOGRAPHIC MAP
EDEN, NC QUADRANGLE
DATED 1969 REVISED 1997
SCALE 1” = 2,000’
SITE
SOURCE:
ROCKINGHAM COUNTY GIS AERIAL
PHOTOGRAPH
2016
SCALE 1 Inch = 70 Feet
FIGURE 2SITE AERIAL MAP
SUPERIOR CAR WASH102 BOONE ROADEDEN, NORTH CAROLINANCDEQ INCIDENT No. 30023
ECS PROJECT No. 49:3623-C
APPROXIMATE SITE BOUNDARY
SOURCE:
ECS FIELD NOTES
2017
SCALE 1 Inch = 25 Feet
FIGURE 3MONITORING WELL LOCATION MAP
SUPERIOR CAR WASH102 BOONE ROADEDEN, NORTH CAROLINANCDEQ INCIDENT No. 30023
ECS PROJECT No. 49:3623-C
MW-10
MW-8
MW-9
West Meadow Road
Boone RoadFormer USTs
Location
MW-7
MW-6
MW-11
Smith River
Former Superior
Car Wash
Circle Mart
Gasoline Station
Dispenser
Island
Circle Mart USTs
located approximately
40 feet south
Approximate
Geophysical
Survey Area
TABLE 1
UST SYSTEM INFORMATION
Superior Car Wash
102 Boone Road
Eden, Rockingham County, North Carolina
NCDEQ Incident No.: 30023
ECS Project 49:3623-C
UST ID
Number
Last
Contents
Previous
Contents
Capacity
(in Gallons)
Construction
Details Tank Dimensions Installation
Date Status Release
1 Gasoline Unknown 1,000 Single Wall Steel 3' 8" X 12' Unknown Removed - 3/16/10 Yes
2 Gasoline Unknown 550 Single Wall Steel 3' X 5'Unknown Removed - 3/16/10 Yes