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Home My WebLink AboutMO-6396_24219_CA_MRP_20230817SUBSEQUENT MONITORING REPORT FORMER PANTRY #342 (INCIDENT NO. 24219) 2100 SOUTH NEW HOPE ROAD GASTONIA, GASTON COUNTY, NORTH CAROLINA ESP Project No. 23-00200-074 Prepared For: North Carolina Department of Environmental Quality Division of Waste Management 1646 Mail Service Center Raleigh, North Carolina 27699-1646 Prepared By: ESP Associates, Inc. P. O. Box 7030 Charlotte, North Carolina 28241 August 17, 2023 ESP Associates, Inc. P.O. Box 7030 • Charlotte, NC 28241 1.800.960.7317 • NC: 704.583.4949, fax 704.583.4950 • SC: 803.802.2440, fax 803.802.2515 www.espassociates.com August 17, 2023 Mr. Scott Ryals North Carolina Department of Environmental Quality Division of Waste Management 1646 Mail Service Center Raleigh, North Carolina 27699-1646 Email: scott.ryals@deq.nc.gov Reference: SUBSEQUENT MONITORING REPORT Former Pantry #342 (Incident #24219) 2100 South New Hope Road Gastonia, Gaston County, North Carolina ESP Project No. 23-00200-074 Dear Mr. Ryals: ESP Associates, Inc. (ESP) is pleased to present this Subsequent Monitoring Report documenting activities performed at the subject site, Former Pantry #342, in accordance with North Carolina Department of Environmental Quality (NCDEQ), Task Authorization No. 1, approved on May 22, 2023. The subject site is located at 2100 South New Hope Road in Gastonia, Gaston County, North Carolina. We appreciate the opportunity to provide environmental services on this project. If you should have any questions, please do not hesitate to contact us at (704) 583-4949. Sincerely, ESP Associates, Inc. Matthew R. Craig Christopher J. Ward, PG, RSM Project Manager Senior Geologist Attachment – Subsequent Monitoring Report TABLE OF CONTENTS Section Page SITE INFORMATION ..................................................................................................................... i EXECUTIVE SUMMARY ............................................................................................................. iii 1.0 INTRODUCTION ............................................................................................................... 1 1.1 SITE SETTING ........................................................................................................... 1 1.2 SITE GEOLOGY AND HYDROGEOLOGY ................................................................. 1 1.3 SURFACE WATER ..................................................................................................... 2 1.4 WATER SUPPLY WELLS ........................................................................................... 2 2.0 SITE HISTORY .................................................................................................................. 3 3.0 FIELD ACTIVITIES ........................................................................................................... 5 3.1 FREE PRODUCT EVALUATION ................................................................................ 5 3.2 WATER LEVEL GAUGING ........................................................................................ 5 3.3 MONITORING WELL SAMPLING ............................................................................. 5 3.4 FIELD QUALITY CONTROL SAMPLING AND ANALYSIS ....................................... 6 4.0 ANALYTICAL RESULTS .................................................................................................. 7 5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 8 6.0 REFERENCES ................................................................................................................. 10 FIGURES Figure 1 USGS Topographic Site Location Map Figure 2 Site Map Figure 3 Groundwater Elevation Map Figure 4 Groundwater Results Map Figure 5 Benzene Isoconcentration Map TABLES Table 1 Monitoring Well Construction and Groundwater Data Table 2 Summary of Groundwater Analytical Results APPENDICES Appendix A Tables of Previous Groundwater Elevations and Analytical Results Appendix B Field Documentation and Photographs Appendix C Laboratory Data Reports Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 i SITE INFORMATION Date of Report: August 17, 2023 NCDEQ Incident No: 24219 NCDEQ UST No.: MO-6396 Site Name: Former Pantry #342 Site Location: 2100 South New Hope Road Gastonia, Gaston County, North Carolina 28054 Latitude: N 35.242772 Longitude: W 81.130139 UST Owner/ Operator: Unknown Current Property Owner: Park Lane Properties PO Box 2552 Gastonia, North Carolina 28053 Charlie Pearson (704) 460-8402 Current Property Occupant: Multi-tenant building occupied by a laundromat and Boost Mobile store Consultant: ESP Associates, Inc. P.O. Box 7030 Charlotte, North Carolina 28241 (704) 583-4949 Laboratory: Pace Analytical Services, LLC NCDEQ No. 5342 9800 Kincey Avenue Huntersville, North Carolina 28028 (704) 875-9092 Release Information: Release Discovery Date: March 2002 Estimate Quantity: Unknown Cause of Release: Former UST system Source of Release: Former UST system; three steel USTs containing various grades of gasoline Currently Active Tanks: None Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 ii I, Christopher J. Ward, a Professional Geologist for ESP Associates, Inc., do certify that the information contained in this report is correct and accurate to the best of my knowledge. ESP Associates, Inc. is licensed to practice both geology and engineering in North Carolina. ESP Associates, Inc.’ certification numbers are: Geology: C-556 / Engineering: F-1407 Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 iii EXECUTIVE SUMMARY This executive summary section provides an abbreviated reporting of our Site observations and findings. Refer to the main text and appendices for a complete reporting of our observations and findings. ESP Associates, Inc. (ESP) has completed a Subsequent Monitoring Report documenting assessment activities performed at the Former Pantry #342 site (Incident No. 24219). The approximate 0.35-acre site (Tax Parcel No. 115988) is located at 2100 South New Hope Road in Gastonia, Gaston County, North Carolina. This report was completed to summarize the findings of assessment activities performed on June 12, 2023, in accordance with North Carolina Department of Environmental Quality (NCDEQ), Task Authorization No. 1, approved on May 22, 2023. The work was performed as part of the State Lead Contract #N70522-D between NCDEQ and ESP. This report was prepared in general accordance with the 15A NCAC 2L .0115 regulations and the NCDEQ Underground Storage Tank (UST) Section Guidelines for Assessment and Corrective Action for UST Releases, January 2021, under the supervision of Christopher J. Ward, North Carolina registered professional geologist (North Carolina License No. 1600). Field activities performed by ESP on June 12, 2023, included: • Gauging static water levels in monitoring wells MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9; and • Collecting groundwater samples from MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9, including a field duplicate. Collected water samples were analyzed for volatile organic compounds (VOCs) for comparison to both North Carolina Groundwater Quality Standards 15A NCAC 2L .0202 (2L Standards) and Gross Contaminant Levels (GCLs). Based on results of the above field activities and previous reporting, ESP concludes the following: • Static water level depths ranged from 17.40 to 21.35 ft ft bTOC; • Free product was not encountered within any of the gauged monitoring wells; • General direction of shallow groundwater flow beneath the site is to the southeast; • The site and surrounding areas are reportedly connected to municipal water; • No active water supply wells are reportedly located within 1,000-feet of the site; • In MW-1, benzene was the only analyte detected above its GCL while IPE, ethylbenzene, isopropylbenzene, MTBE, naphthalene, n-propylbenzene, toluene, 1,2,4- trimethylbenzene, m&p xylenes, and o-xylene were detected above their 2L standards; • In MW-4, only benzene was detected above its 2L standard; • In MW-7, only MTBE was detected above its 2L standard; and • In MW-5, MW-8, or MW-9, no analytes were detected above 2L standards. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 iv The general trend in groundwater concentrations since June 2020 has been the following: • MW-1 - analyte concentrations have remained relatively stable, while benzene has remained above its GCL; • MW-4 - analyte concentrations have remained mostly below 2L standards except for benzene which has been detected slightly above 2L standards; • MW-5 - all analyte concentrations have remained below 2L standards; • MW-7 - analyte concentrations have remained relatively stable; • MW-8 - all analyte concentrations have remained below 2L standards; and • MW-9 - all analyte concentrations have remained below 2L standards. Additionally, it appears that the February 7, 2022, AFVR event at MW-1 has had only minor impacts on reducing contaminant concentrations at that location. Based on the above results, ESP offers the following recommendations: • Continue to sample site monitoring wells on a semiannual basis to further understand concentration trends and plume stability; and • Consider injection of either an ISCO product that can be used to address remaining soil contaminants (such as CleanOx) or BOS200 which is a trap and treat activated carbon- based biodegradation product. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 1 1.0 INTRODUCTION 1.1 Site Setting The Former Pantry #342 site is an approximate 0.35-acre developed site (Tax Parcel No. 115988) located at 2100 South New Hope Road in Gastonia, Gaston County, North Carolina (see Figures 1 and 2). The site includes an approximate 2,400-sqft active mixed commercial building built in 1983 along with paved surfaces on the southern and eastern portions of the tax parcel. The site is bordered to the south by South New Hope Road, to the west by Huntsmoor Drive, to the north by a commercial property, and to the east by Ashbrook High School. 1.2 Site Geology and Hydrogeology Consideration of surface and subsurface drainage and geology are of interest since they provide an indication of the direction that contamination, if present on-site or off-site, could be transported. The site is located near the contact of the Battleground formation and adjacent igneous rocks within the Kings Mountain Belt of the Piedmont Physiographic Province. The Piedmont Physiographic Province generally consists of low to medium elevation, rounded hills, and long rolling northeast to southwest trending ridges with incised creeks and river channels. Rocks in the site belonging to the Battleground formation consist of Late Proterozoic-aged quartz-sericite schist with metavolcanic rock, quartz-pebble metaconglomerate, kyanite-sillimanite quartzite, and garnet- quartz rock. Igneous rocks of the adjacent contact are described as Phanerozoic-aged, metamorphosed quartz diorite. In-place chemical and physical weathering of parent rocks typically form residual soils in the Piedmont region. Weathering is facilitated by the presence of fractures, joints, and less resistant minerals in the rock. In areas not altered by erosion, alluvial deposition or anthropomorphic activities, the typical residual soil profile consists of clay-rich unconsolidated materials at the surface, transitioning to sandy silts and silty sands at depth. Typically, the boundary between soil and rock is not sharply defined. This transitional zone is termed “partially weathered rock” or saprolite. Information obtained from the Web Soil Survey shows soils on the site as Cecil-Urban land complex (CfB) 2 to 8 percent slopes and Urban Land (Ur). In the Piedmont, groundwater generally occurs in pore spaces within soils and in the structural features present in the underlying rock (i.e., joints, fractures, and faults). Recharge to the water table is primarily by precipitation infiltrating the surficial soils and percolating downward under the influence of gravity to the water table. Typically, the water table is not a level surface, but a subdued reflection of the land surface. The depth to the water table is not consistent and is dependent upon several factors that include the amount of rainfall, permeability of the soil, the extent of fracturing in the underlying rock and the influences of groundwater pumping. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 2 The direction and movement of groundwater is generally dependent on soil type, the presence of relict structures, and the textures of surrounding earth materials. Fractures, faults, folds, and foliation planes affect the migration of groundwater in rock. No major geologic features (faults, etc.) are present at or near the site. Groundwater typically flows in directions parallel to the ground surface and under the influence of gravity, migrates to discharge points such as surface water features, the toes of slopes or natural springs. Fluctuations in the depth of the water table can be expected depending on variations in precipitation, surface water run-off and other factors. Normally, the highest levels of the water table occur in late winter and spring and the lowest levels occur in the late summer and fall. Based on data from June 12, 2023, water level measurements, shallow groundwater at the site is expected to flow generally to the southeast. 1.3 Surface Water The site is located within the drainage basin of Stanley Creek, which, at its closest point, is located approximately 1,200 feet east of the site. Stanley Creek drains into the Catawba River. No surface water features were observed within 1,000 feet of the source area (see Figure 1). 1.4 Water Supply Wells Based on previous work by others, there are reportedly no active water supply wells within 1,000 of the site; however, it has been previously reported that an inactive water supply well is located approximately 750 west of the site. The water supply well is reportedly out-of-service and the property containing the well is provided with municipal water. The site and adjacent properties are reportedly connected to municipal water. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 3 2.0 SITE HISTORY The following description of historical site activities was obtained from a report titled “Subsequent Monitoring Report, Former Pantry #342” dated May 9, 2018, by Terracon Consultants Inc. (Terracon) and two separate reports titled “Letter Report, Former Pantry #342” dated November 16, 2021 and June 2, 2022, by Terracon. • Excel Civil & Environmental Associates (Excel) was contracted to complete a Limited Site Assessment (LSA) at the site in response to a Notice of Regulatory Requirements (NORR) dated May 1, 2002. Excel installed eight monitoring wells, conducted soil sampling, and completed a well receptor survey at the site. Laboratory analysis of the soil and groundwater samples indicated the presence of contaminated soils in the former UST basin below Residential Maximum Soil Contaminant Concentrations (MSCCs) but also confirmed groundwater contamination in monitoring wells MW-1 through MW-5, MW-7, VW-1, and VW-2 above 2L groundwater standards. Benzene was reportedly detected in wells MW-1, MW-7, and VW-1 in excess of its GCL. • Excel completed a Comprehensive Site Assessment (CSA) in 2002 that included the installation of three additional groundwater monitoring wells and additional soil sampling on the site and adjacent properties. Based on the soil samples collected during the CSA activities, Excel estimated BTEX constituents were present in the soils above Soil-to-Water MSCCs in an approximate 18,000 square- foot portion of the property. The highest concentrations were present near the former fuel dispensers. Excel identified various other petroleum constituents within the on-site soils above regulatory limits. None of the samples exceeded Industrial/Commercial MSCCs. Excel detected groundwater constituents in excess of the GCLs in monitoring wells MW-1, MW-7, VW-1, and VW-3. • Crawford Environmental Services (CES) mobilized to the site in September 2012 to collect groundwater samples and update historical receptor information. CES was unable to locate monitoring wells MW-2, MW-3, and MW-6 at the site. Laboratory analysis of the samples collected by CES indicated that contaminant concentrations had dropped significantly at the site and none of the petroleum constituents were detected above GCLs except for well MW-1. • In March 2015, Terracon mobilized to the site to collect groundwater samples from multiple on-site wells. Terracon was unable to locate monitoring wells MW-2, MW-3, and MW-6 at the site. Laboratory analysis of the samples indicated various petroleum constituents in wells MW-1, MW-4, MW-7, VW-1, VW-2, and VW-3 above their respective 2L groundwater standards. Benzene was detected above its GCL in well MW-1. Terracon recommended the installation of a “bio-sock” in well MW-1 and annual groundwater sampling of the site. • On March 29, 2018, Terracon mobilized to the site to conduct groundwater sampling. Prior to sample collection, Terracon gauged groundwater levels in monitoring wells MW-1, MW-4, MW-5, MW-7 through MW-9, VW-1, VW-2, and VW-3. Terracon was Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 4 unable to locate wells MW-2, MW-3, and MW-6. Petroleum constituents were detected in wells MW-1, MW-4, MW-7, VW-1, VW-2, and VW-3. Benzene was detected in MW-1 at a concentration above its Gross Contamination Level (GCL) while various analytes were detected above their respective 15A NCAC 2L standards. Various analytes were detected above their respective 2L standards in MW-7, VW-1, and VW-3. • On October 21, 2021, Terracon mobilized to the site to collect a groundwater sample from MW-1 and to install an O-Sox insert within the well. Benzene was detected in MW-1 above its GCL while various analytes were detected above their respective 2L standards. • On February 7, 2022, Terracon mobilized to the site to perform an 8-hour AFVR event using MW-1 as the target extraction well. Approximately 169.07 pounds (20.25 equivalent gallons) of VOCs were extracted during the event. • On March 7, 2021, Terracon mobilized to the site to collect a groundwater sample from MW-1. Benzene was detected in MW-1 above its GCL while various analytes were detected above their respective 2L standards. Some decrease in petroleum constituents in groundwater from MW-1 was observed after the February 7, 2022, AFVR event. Historical groundwater elevations and analytical results are provided in Appendix A. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 5 3.0 FIELD ACTIVITIES Field activities performed by ESP on June 12, 2023, included: • Gauging static water levels in monitoring wells MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9; and • Collecting groundwater samples from MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9, including a field duplicate. Sample locations are depicted on Figure 2. Field logbook entries along with water level survey, groundwater sampling, and field instrument calibration forms were completed in the field to document site activities (see Appendix B). Photographs are also provided in Appendix B. Details of field activities are provided below. 3.1 Free Product Evaluation Free product was not encountered within any of the gauged monitoring wells. 3.2 Water Level Gauging On June 12, 2023, prior to purging or collecting groundwater samples, depth to groundwater from the top of casing (TOC) within monitoring wells MW-1, MW-4, MW-5, MW-7, MW-8, and MW- 9 was measured and recorded using a decontaminated electronic water level meter. It should be noted that monitoring wells MW-2, MW-3, and MW-6 could not be located in the field. The water level measurements were collected by first removing covers and plunger caps from all site monitoring wells and allowing water within the wells to stabilize. The electronic water level meter probe was then lowered into the well and the depth to water measured relative to the well’s TOC. As noted on Table 1, static water level depths ranged from 17.40 to 21.35 ft below top of casing (ft bTOC). Figure 3 depicts the groundwater elevations based off a benchmark of 100.00 ft given to the MW-1 TOC. As depicted on Figure 3, shallow groundwater flow beneath the site is toward the southeast. 3.3 Monitoring Well Sampling On June 12, 2023, groundwater samples were collected from monitoring wells MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9, including a field duplicate of MW-7. Groundwater samples were collected using dedicated and disposable polyvinyl chloride (PVC) bailers (1.5” x 3’) attached to braided nylon rope. Prior to groundwater sample collection, each well was purged using the bailer. During purging, water quality parameters including pH, conductivity, temperature, and turbidity were measured using calibrated field water quality instruments. Readings were taken at the start of purging and periodically until a minimum of three Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 6 well volumes were removed from the well and water quality parameters stabilized. Following purging, a groundwater sample for laboratory analysis was collected from the well using the bailer. The water quality parameters were recorded on groundwater sampling forms along with time, water level depth, and cumulative volume of water purged (see groundwater sampling forms in Appendix B). Groundwater samples were collected following Guidelines for Sampling by the Underground Storage Tank Section, Division of Waste Management, North Carolina Department of Environmental Quality (NCDEQ, 2022). Groundwater samples were placed in laboratory- prepared vials preserved with hydrochloric acid (HCl), labeled, and stored on ice in a cooler for subsequent delivery under standard chain-of-custody (COC) procedures to Pace Analytical (Pace), a North Carolina-certified laboratory, located in Huntersville, North Carolina, for analysis. The groundwater samples were analyzed for VOCs by EPA Method 6200B including MTBE, ethylene dibromide (EDB), and isopropyl ether (IPE). 3.4 Field Quality Control Sampling and Analysis A field duplicate groundwater sample was collected on June 12, 2023, from MW-7 and analyzed for VOCs by EPA Method 6200B including MTBE, EDB, and IPE to assess variance between collected samples. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 7 4.0 ANALYTICAL RESULTS Results of the laboratory analysis of groundwater samples MW-1, MW-4, MW-5, MW-7, MW-8, and MW-9 and duplicate of MW-7 are tabulated in Table 2. As noted in Table 2, the analytical results are compared to both 2L standards and GCLs. The Pace laboratory analytical report is provided in Appendix C. Benzene was detected at a concentration exceeding its GCL in MW-1 while various analytes were detected above their 2L standards in MW-1, MW-4, and MW-7 (including duplicate). No analytes were detected above 2L standards in MW-5, MW-8, or MW-9. A summary of the analytical results is as follows: • MW-1 - benzene (6,580 µg/L) was the only analyte detected above its GCL while IPE (106 µg/L), ethylbenzene (1,720 µg/L), isopropylbenzene (101 µg/L), MTBE (221 µg/L), naphthalene (223 µg/L), n-propylbenzene (184 µg/L), toluene (6,350 µg/L), 1,2,4- trimethylbenzene (916 µg/L), m&p xylenes (3,260 µg/L), and o-xylene (2,190 µg/L) were detected above their 2L standards; • MW-4 - benzene (3.2 µg/L) was detected above its 2L standard; • MW-7 - MTBE (36.1 µg/L) was detected above its 2L standard; • MW-5, MW-8, and MW-9 - no analytes detected above 2L standards; and • The field duplicate sample results were consistent with results for MW-7. A comparison of groundwater laboratory analytical results from the June 12, 2023, sampling event to previous sampling events since June 2020 reveals the following: • MW-1 - analyte concentrations have remained relatively stable, while benzene has remained above its GCL; • MW-4 - analyte concentrations have remained mostly below 2L standards except for benzene which has been detected slightly above 2L standards; • MW-5 - all analyte concentrations have remained below 2L standards; • MW-7 - analyte concentrations have remained relatively stable; • MW-8 - all analyte concentrations have remained below 2L standards; and • MW-9 - all analyte concentrations have remained below 2L standards. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 8 5.0 CONCLUSIONS AND RECOMMENDATIONS Based on results of the above field activities and previous reporting, ESP concludes the following: • Static water level depths ranged from 17.40 to 21.35 ft ft bTOC; • Free product was not encountered within any of the gauged monitoring wells; • General direction of shallow groundwater flow beneath the site is to the southeast; • The site and surrounding areas are reportedly connected to municipal water; • No active water supply wells are reportedly located within 1,000-feet of the site; • In MW-1, benzene was the only analyte detected above its GCL while IPE, ethylbenzene, isopropylbenzene, MTBE, naphthalene, n-propylbenzene, toluene, 1,2,4- trimethylbenzene, m&p xylenes, and o-xylene were detected above their 2L standards; • In MW-4, only benzene was detected above its 2L standard; • In MW-7, only MTBE was detected above its 2L standard; and • In MW-5, MW-8, or MW-9, no analytes were detected above 2L standards. The general trend in groundwater concentrations since June 2020 has been the following: • MW-1 - analyte concentrations have remained relatively stable, while benzene has remained above its GCL; • MW-4 - analyte concentrations have remained mostly below 2L standards except for benzene which has been detected slightly above 2L standards; • MW-5 - all analyte concentrations have remained below 2L standards; • MW-7 - analyte concentrations have remained relatively stable; • MW-8 - all analyte concentrations have remained below 2L standards; and • MW-9 - all analyte concentrations have remained below 2L standards. Additionally, it appears that the February 7, 2022, AFVR event at MW-1 has had only minor impacts on reducing contaminant concentrations at that location. Based on the above results, ESP offers the following recommendations: • Continue to sample site monitoring wells on a semiannual basis to further understand concentration trends and plume stability; and • Consider injection of either an ISCO product that can be used to address remaining soil contaminants (such as CleanOx) or BOS200 which is a trap and treat activated carbon- based biodegradation product. Subsequent Monitoring Report ESP Project No. 23-00200-074 Former Pantry #342 (Incident #24219) August 17, 2023 9 6.0 REFERENCES Gaston County, North Carolina GIS website, https://gis.gastongov.com/ 1985 Geologic Map of North Carolina, The North Carolina Geological Survey, Phillip M. Brown, 1985. Guideline for Sampling Underground Storage Tank Section, Division of Waste Management, North Carolina Division of Environmental Quality, March 7, 2022, Change 4. Terracon, November 16, 2021, Letter Report: Former Pantry #342 (Incident #24219), 2100 South New Hope Road, Gastonia, Gaston County, North Carolina. Terracon, May 09, 2018, Subsequent Monitoring Report: Former Pantry #342 (Incident #24219), 2100 South New Hope Road, Gastonia, Gaston County, North Carolina. FIGURES 0 350 700Feet ESP Associates, Inc. P.O. Box 7030Charlotte, NC 28241 Phone 704.583.4949 www.espassociates.com SHEET TITLE PROJECT PROJECT NO. SCALE DRAWN BY CHECKED BY 23-00200-074 ET CWDATE07/10/2023 FIGURE 1USGS TOPOGRAPHIC SITE LOCATION MAPµAs Shown GASTONIA, NORTH CAROLINA SITE BOUNDARY All locations are approximate. FORMER PANTRY #342 LEGEND: STRIP MALL BUILDING <<< < < << < << MW-1VW-1 MW-3 MW-9 MW-5 MW-4 VW-2 MW-7 VW-3 MW-8 < < MW-6 MW-2 SOUTH NEW HOPE ROADHUNTSMOOR DRIVEFORMER CANOPY FORMER UST BASINS 0 20 40Feet ESP Associates, Inc. P.O. Box 7030Charlotte, NC 28241 Phone 704.583.4949 www.espassociates.com SHEET TITLE PROJECT PROJECT NO. SCALE DRAWN BY CHECKED BY 23-00200-074 ET CWDATE07/10/2023 FIGURE 2SITE MAPµAs Shown GASTONIA, NORTH CAROLINA SITE BOUNDARY MONITORING WELL All locations are approximate. FORMER PANTRY #342 LEGEND: < STRIP MALL BUILDING <<< < < << < << MW-1VW-1 MW-3 MW-9 MW-5 MW-4 VW-2 MW-7 VW-3 MW-8 < < MW-6 MW-2 SOUTH NEW HOPE ROADHUNTSMOOR DRIVE0 10 20Feet ESP Associates, Inc. P.O. Box 7030Charlotte, NC 28241 Phone 704.583.4949 www.espassociates.com SHEET TITLE PROJECT PROJECT NO. SCALE DRAWN BY CHECKED BY 23-00200-074 ET CWDATE07/10/2023 FIGURE 3GROUNDWATER ELEVATION MAPµAs Shown GASTONIA, NORTH CAROLINA SITE BOUNDARYMONITORING WELLESTIMATED GROUNDWATER ELEVATION CONTOURESTIMATED GROUNDWATER FLOW DIRECTION All locations are approximate. FORMER PANTRY #342 LEGEND: < <<< < < << < << MW-1VW-1 MW-3 MW-9 MW-5 MW-4 VW-2 MW-7 VW-3 MW-8 < < MW-6 MW-2 SOUTH NEW HOPE ROADHUNTSMOOR DRIVE0 20 40Feet ESP Associates, Inc. P.O. Box 7030Charlotte, NC 28241 Phone 704.583.4949 www.espassociates.com SHEET TITLE PROJECT PROJECT NO. SCALE DRAWN BY CHECKED BY 23-00200-074 ET CWDATE07/10/2023 FIGURE 4GROUNDWATER RESULTS MAPµAs Shown GASTONIA, NORTH CAROLINA SITE BOUNDARY MONITORING WELL All locations are approximate. FORMER PANTRY #342 LEGEND: < <<< < < << < << MW-1VW-1 MW-3 MW-9 MW-5 MW-4 VW-2 MW-7 VW-3 MW-8 < < MW-6 MW-2 SOUTH NEW HOPE ROADHUNTSMOOR DRIVE0 20 40Feet ESP Associates, Inc. P.O. Box 7030Charlotte, NC 28241 Phone 704.583.4949 www.espassociates.com SHEET TITLE PROJECT PROJECT NO. SCALE DRAWN BY CHECKED BY 23-00200-074 ET CWDATE07/10/2023 FIGURE 5BENZENE ISOCONCENTRATION MAPµAs Shown GASTONIA, NORTH CAROLINA SITE BOUNDARY MONITORING WELL APPROXIMATE CONCENTRATION CONTOUR All locations are approximate. FORMER PANTRY #342 LEGEND: < TABLES Table 1 Monitoring Well Construction and Groundwater Elevation Data Former Pantry #342 Gastonia, North Carolina NCDEQ Incident No. 24219 Well ID Date Intalled Screened Interval (ft BGS) a Bottom of Well (ft BGS) a Top of Casing Elevation (ft) a,b Date Water Level Measured Depth to Water from Top of Casing (ft bTOC) Groundwater Elevation (ft) 11/6/2019 21.96 78.04 6/25/2020 15.14 84.86 10/21/2021 20.39 79.61 6/12/2023 17.40 82.60 9/4/2012 22.64 77.66 3/17/2015 17.37 82.93 3/29/2018 21.13 79.17 6/12/2023 17.80 82.50 9/4/2012 25.57 78.76 3/17/2015 21.20 83.13 3/29/2018 24.59 79.74 6/12/2023 21.35 82.98 9/4/2012 23.13 77.25 3/17/2015 17.75 82.63 3/29/2018 21.42 78.96 6/12/2023 18.20 82.18 9/4/2012 26.08 78.70 3/17/2015 21.60 83.18 3/29/2018 25.10 79.68 6/12/2023 21.20 83.58 9/4/2012 23.92 78.92 3/17/2015 19.57 83.27 3/29/2018 23.04 79.80 6/12/2023 19.34 83.50 9/4/2012 22.38 - 3/17/2015 17.21 - 3/29/2018 21.28 - 6/12/2023 9/4/2012 22.67 - 3/17/2015 17.55 - 3/29/2018 21.07 - 6/12/2023 9/4/2012 23.42 - 3/17/2015 17.82 - 3/29/2018 21.66 - 6/12/2023 Notes: a Top of casing elevations, screened intervals, and bottom of well measurements are from previous consultants' monitoring reports. b Top of casing elevations are based off of an assumed benchmark elevation of 100 ft given to MW-1. - no information available BGS - below ground surface ft - feet ft bTOC - feet below TOC TOC - top of casing Not Measured Not Measured Not Measured VW-3 1/3/2003 35-40 37.0 - VW-2 8/7/2002 36-41 41.3 - VW-1 6/18/2002 30-35 39.6 - MW-9 1/2/2003 15-30 32.6 102.84 MW-8 1/2/2003 20-35 33.5 104.78 MW-7 8/6/2002 15-30 28.3 100.38 8/6/2002 MW-1 MW-4 MW-5 100.00 100.30 104.33 15-30 15-30 15-30 29.4 28.5 29.0 6/19/2002 6/19/2002 Table 2 Summary of Groundwater Analytical Results Former Pantry #342 Gastonia, North Carolina NCDEQ Incident No. 24219 (Page 1 of 1) 1 70 70 70 70 3 70 600 70 20 6 70 600 3 400 400 500 500 500 5,000 5,900 8,800 14,750 70,000 3,000 70,000 80,000 30,500 20,000 6,000 26,100 260,000 3,000 28,500 24,100 50,000 50,000 50,000 6/25/20 5,200 <14.1 <9.8 <10.0 <14.1 <16.6 119 1,200 79.9 393 196 <9.6 1,290 <9.3 600 <9.1 3,240 NR NR 10/21/21 8,550 <24.5 <20.0 <16.2 25.3 <27.0 145 1,780 96.5 385 334 185 9,970 <19.2 1,010 250.0 6,640 NR NR 3/7/22 6,460 24.5 <16.0 <12.9 <14.1 <21.6 140 1,330 87.9 376 262 <13.6 3,490 <15.3 638 <13.3 3,720 NR NR 6/12/23 6,580 <24.5 <20.0 <16.2 <21.5 <21.5 106 1,720 101 221 223 184 6,350 <19.2 916 205 NR 3,260 2,190 9/4/12 7.0 ND ND ND ND 17.0 5.4 1.9 0.41J 37.0 1.5 0.46J 1.6 ND 11.0 1.9 3.2 NR NR 3/17/15 2.4 <0.25 0.47J <0.25 <0.25 <0.50 0.6 1.3 2.5 5.0 3.1 4.2 <0.25 ND <0.25 <0.25 <0.50 NR NR 3/29/18 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 0.25J <0.25 <0.25 <0.25 <0.25 <0.75 NR NR 6/12/23 3.2 <0.49 <0.40 <0.32 <0.43 <0.43 <0.31 2.2 <0.33 <0.42 <0.64 <0.34 13.0 <0.38 1.1 <0.33 NR 5.7 3.4 9/4/12 ND ND ND ND ND 4.0 ND ND ND ND ND ND ND ND ND ND ND NR NR 3/17/15 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 ND <0.25 <0.25 <0.50 NR NR 3/29/18 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 <0.25 <0.25 <0.25 <0.75 NR NR 6/12/23 <0.34 <0.49 <0.40 <0.32 <0.43 <0.43 <0.31 <0.30 <0.33 <0.42 <0.64 <0.34 0.49 J <0.38 <0.50 <0.33 NR <0.71 <0.34 9/4/12 120 ND 0.5 ND ND 25.0 170 1.2 3.8 1,400 11.0 ND 2.6 ND 31.0 9.1 132 NR NR 3/17/15 5.2 <0.25 <0.25 <0.25 <0.25 <0.50 63.9 <0.25 0.35J 557 1.3J <0.25 <0.25 ND 1.0 0.6 4.5 NR NR 3/29/18 25.3 <2.5 <2.5 <2.5 <2.5 <5.0 76.4 3.4J <2.5 1,130 15.2J <2.5 8.1 3.1J 10.4 <2.5 33.5 NR NR 6/12/23 <0.34 <0.49 <0.40 <0.32 <0.43 <0.43 3.0 <0.30 <0.33 36.1 <0.64 <0.34 <0.24 <0.38 <0.50 <0.33 NR <0.71 <0.34 Duplicate (MW-7)6/12/23 <0.34 <0.49 <0.40 <0.32 <0.43 <0.43 3.0 <0.30 <0.33 35.7 <0.64 <0.34 <0.24 <0.38 <0.50 <0.33 NR <0.71 <0.34 5/8/09 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND NR NR 3/17/15 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 ND <0.25 <0.25 <0.50 NR NR 3/29/18 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 <0.25 <0.25 <0.25 <0.75 NR NR 6/12/23 0.83 <0.49 <0.40 <0.32 <0.43 <0.43 <0.31 1.2 <0.33 <0.42 <0.64 <0.34 3.3 <0.38 0.75 <0.33 NR 2.5 1.5 5/8/09 ND ND ND ND 0.36J ND ND ND ND 0.15J ND ND 0.41J ND ND ND ND NR NR 3/17/15 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 ND <0.25 <0.25 <0.50 NR NR 3/29/18 <0.25 <0.25 <0.25 <0.25 <0.25 <0.50 <0.25 <0.25 <0.25 <0.25 <1.0 <0.25 <0.25 <0.25 <0.25 <0.25 <0.75 NR NR 6/12/23 0.75 <0.49 <0.40 <0.32 <0.43 <0.43 <0.31 1.1 <0.33 <0.42 <0.64 <0.34 4.9 <0.38 0.75 <0.33 NR 2.9 1.6 Notes: Bold values indicate constituent concentrations were greater than the 2L Standard. Yellow highlighted values indicate constituent concentrations were greater than the GCL. Samples presented prior to the June 12, 2023 event were obtained from previous consultants reports. <## - less than the method detection limit µg/L - micrograms per liter 2L Standard - North Carolina 02L standard for groundwater GCL - Gross Contaminant Level J - Estimated concentration above the method detection limit and below the reporting limit. NR - not reported ND - reportedly not detected m&p-Xyleneo-XyleneDiisopropyl ether (IPE)ChloroformToluene1,2,4-Trimethylbenzene1,3,5-TrimethylbenzeneXylene (Total)Naphthalenen-PropylbenzeneTrichloroetheneChloromethaneEthylbenzeneIsopropylbenzene (cumene)Methyl Tert-Butyl Ethyl (MTBE)Benzenen-Butylbenzenesec-Butylbenzenetert-ButylbenzeneMW-7 MW-8 MW-9 GCL (µg/L) Sample ID Collection Date MW-1 MW-4 MW-5 2L Standard (µg/L) APPENDICES APPENDIX A APPENDIX B SITE PHOTOGRAPHS APPENDIX C ESP Corporate Office 3475 Lakemont Boulevard Fort Mill, SC 29708 803.802.2440 Mailing Address: P.O. Box 7030 Charlotte, NC 28241 800.960.7317 | www.espassociates.com Concord 7144 Weddington Rd. NW Suite 110 Concord, NC 28027 704.793.9855 Cornelius 20484 Chartwell Center Dr. Suite D Cornelius, NC 28031 704.649.2863 Raleigh 2200 Gateway Centre Blvd. Suite 216 Morrisville, NC 27560 919.678.1070 Greensboro 7011 Albert Pick Rd Suite E Greensboro, NC 27409 336.334.7724 Wilmington 211 Racine Drive Suite 101 Wilmington, NC 28403 910.313.6648 Charleston 2154 North Center Street Suite E-503 North Charleston, SC 29406 843.714.2040 Nashville 500 Wilson Pike Circle Suite 310 Brentwood, TN 37027 615.760.8300 Pittsburgh One Williamsburg Place Suite G-5, Box 13 Warrendale, PA 15086 724.462.6606 Bradenton 518 13th Street West Bradenton, FL 34205 941.345.5451 Indianapolis 8673 Bash Street Indianapolis, IN 46256 317.537.6979 Albuquerque 1203 West Ella Drive Corrales, NM 87048 505.314.1322 Birmingham 291 Cahaba Valley Parkway North Suite A Pelham, AL 35124 205.664.8498 Vickrey & Associates, LLC - An ESP Company San Antonio 12970 Country Parkway San Antonio TX 78216 210.349.3271 Austin 3600 West Parmer Lane Suite 175 Austin, TX 78727 512.494.8014 McAllen 1216 East Jasmine Avenue Suite C McAllen, TX 78501 956.340.0045