AS-4481_41530_CA_AFVR_20171023

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7606 Whitehall Executive Center Drive, Suite 800
Charlotte, NC 28273
Tel: [phone]
Fax: [phone]
www.atcgroupservices.com
N.C. Engineering License No. C-1598

October 23, 2017

Mr. Mike Streeter
North Carolina Department of Environmental Quality
Asheville Regional Office
Division of Waste Management - UST Section
2090 US Highway 70
Swannanoa, North Carolina 28778

Re: Aggressive Fluid/Vapor Recovery (AFVR) Report
Circle K 2723970
225 Cleveland Avenue
Kings Mountain, Cleveland County, North Carolina 28086
Facility ID No. 0-021720
NCDEQ Incident No. 41530
Site Risk: Pending
ATC Project No. CIRK397001

Dear Mr. Streeter:

ATC Associates of North Carolina, P.C. (ATC), on behalf of Circle K Stores, Inc. (Circle K), is submitting
this Aggressive Fluid/Vapor Recovery (AFVR) report for the Circle K 2723970 site in Kings Mountain, North
Carolina. Figure 1 shows the site and vicinity on part of a United States Geological Survey (USGS)
topographic map. A site map illustrating site features and layout is included as Figure 2. This report
summarizes an AFVR event that was conducted on September 6, 2017. The 8-hour AFVR event began at
approximately 08:00 and was completed at approximately 16:00. AFVR services were provided by A&D
Environmental Services LLC (A&D), with oversight provided by ATC. Copies of field data sheets and the
groundwater disposal manifest are included in Appendix A.

The AFVR event was conducted at monitoring well MW-6 due to free product petroleum observed in the well
during a March 2017 groundwater sampling event. The March 2017 sampling event was completed to monitor
dissolved chlorinated solvent impact at the site under the Inactive Hazardous Sites Branch Registered
Environmental Consultant Program (site ID NONCD0001939).

Prior to and at the completion of the AFVR event, monitoring wells MW-5, MW-6, and MW-15 were gauged
using an oil/water interface probe. The measured liquid levels are summarized as follows:
Circle K 2723970 - AFVR Report October 23, 2017
NCDEQ Incident No. 41530 ATC Project No. CIRK397001

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GAUGED LIQUID LEVELS PRIOR TO AFVR
MONITORING WELL DEPTH TO PRODUCT
(ft)
DEPTH TO WATER
(ft)
PRODUCT THICKNESS
(ft)
MW-5 - 7.44 -
MW-6 7.90 10.11 2.21
MW-15 - 12.84 -
- = no free product detected

- = no free product detected

During AFVR activity, a liquid ring vacuum pump unit was plumbed to the designated extraction point,
and a drop pipe was extended into the well through an airtight seal at the top of the well casing.
Throughout the AFVR process, a cone of depression was formed around the designated recovery point by
drawing down the product and groundwater surface levels, thus causing product and impacted water
surrounding the recovery point to be extracted. Soil within and above the cone of depression (or
dewatered zone) was also influenced. Petroleum within the soil was removed as vapor by air passing
through the soil.

Approximately 184 gallons of petroleum-impacted groundwater were recovered from monitoring well MW-
6 during the September 6, 2017, AFVR event. Measurable free product was not observed in the truck tank
following the event. Appendix A contains the groundwater disposal manifest. ATC disposed of the
groundwater under a non-hazardous waste profile. The non-hazardous waste characterization is supported by
1) the source of chlorinated impact at the site being unknown (mixture rule for listed wastes does not apply)
and 2) recent water sample results being below the toxicity characteristic leaching procedure (TCLP)
concentrations for impact constituents at the site. Based on calculated recovery volumes, approximately 8.95
pounds (1.43 gallons) of petroleum were recovered as vapor. Readings recorded during the event and
subsequent calculations for AFVR emissions are included in Appendix A.

Although measurable product was not observed in the vacuum truck tank following the event, the extraction
well, MW-6 also did not indicate measurable free product post-AFVR. Well MW-6 contained 2.21 feet of
product prior to the AFVR event so it’s possible the product recovered into the truck was not measurable due
to dispersion through the area of the tank. Also, the total volume of measurable product in the well pre-AFVR
(approximately 0.35 gallons) is a minor portion of the total volume of liquid recovered during the event (184
gallons), making the product level in the truck difficult to measure, particularly so soon after AFVR
completion. Also note that the total volume of liquid recovered was low compared to the full capacity of the
vacuum truck as the intent of the AFVR was to recover product. The drop pipe was placed at the
product/water interface at the beginning of the event and was not lowered substantially into the groundwater
table throughout the event in an effort to reduce potential downward migration of the product into the
groundwater table. The well was only gauged immediately following the AFVR event and ATC did not return
to the site to check for potential product rebound.

Based on boring logs for wells installed in the AFVR event vicinity, the subsurface consists of silty fine sand
with gravel and silt. While this may have higher transmissivity than clay, recovery by AFVR events may be
somewhat limited. However, combining groundwater recovery events with air sparging has proven successful
in similar lithologic areas and could be attempted at this site following subsurface product removal. Historical
slug testing conducted at the site indicated velocities ranging from 0.022 feet per day to 0.081 feet per day.
GAUGED LIQUID LEVELS IMMEDIATELY FOLLOWING AFVR
MONITORING WELL DEPTH TO PRODUCT
(ft)
DEPTH TO WATER
(ft)
PRODUCT THICKNESS
(ft)
MW-5 - 7.37 -
MW-6 - 12.72 -
MW-15 - 12.86 -
Circle K 2723970 - AFVR Report October 23, 2017
NCDEQ Incident No. 41530 ATC Project No. CIRK397001

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The calculated horizontal hydraulic gradient obtained from a recent groundwater monitoring event at the site
indicated a relatively steep 0.025 gradient for the Piedmont area.

The UST system was installed in 1988 by a previous owner and records indicating product line locations are
not available. This information can be obtained with utility designating equipment but is not currently known
to identify potential limitations of a laser-induced fluorescence (LIF) study.

ATC recommends an LIF study to identify the extent and location of subsurface product. Based on results of
the LIF study, if the mass of product is shallow, excavation may be an alternative option to remove product if
recovery events are not deemed sufficient. However, if recovery efforts are the chosen remedial alternative,
recovery wells can be installed in areas of high impact identified during the LIF study, or skimmer systems
can be installed where appropriate.

If you have any questions or comments, please contact us at [phone].

Sincerely,
ATC Associates of North Carolina, P.C.

Christine E. Schaefer Michael D. Shaw, P.G.
Project Manager NC Licensed Geologist #1338

cc: Mr. Brent Puzak – Circle K Stores, Inc.

Attachments:

Figure 1 Site Topographic Map
Figure 2 Site Map
Appendix A Aggressive Fluid/Vapor Recovery Event Data Sheets and Manifest

FIGURES

SITE
LOCATION
DATE:PROJECT NO.:
SCALE:DRAWN BY:
REVIEWED BY:
PROJECT NO.:
DRAWN BY:
REVIEWED BY:
DATE:
SCALE:

APPENDIX A

AGGRESSIVE FLUID/VAPOR RECOVERY EVENT DATA SHEETS AND
MANIFEST
Site: Job #Tank Vol: 3100 gal800 10 -23830 10 -25900 10 -25930 10 -251000 10 -251030 10 -261100 10 -261130 10 -261200 10 -261230 10 -261300 10 -261330 10 -261400 10 -261430 10 -261500 10 -261530 10 -261600 10 -26Circle K Stores, Inc./Circle K 2723970, 225 Cleveland Ave, Kings Mountain, NCMW- MW-7.37 12.86--Depth to free product 20 minutes post-AFVR/EFRDepth to groundwater pre-AFVR/EFRDepth to groundwater post-AFVR/EFRExtraction Well-head Vacuum (in Hg)-- --Depth to free product post-AFVR/EFR7.90 -- --MW-AFVR Field Data SheetClient: ATC Group Services LLCTruck Operator: John Glover6-Sep-17Technician: 10.11 7.44 12.84Blower Rating at 24 in Hg: 492 scfm; 27 in Hg: 103 scfmStingerDepthMW-MW-Influence On Surrounding WellsDepth to Water Below Top of Casing (ft)MW-MW-MW-MW-MW-MW-ExtractionWellsMW- 6 MW- 5 MW-15MW- Stinger Depth MW-612.72Time (hh:mm)MW-6Influence On Surrounding WellsVacuum (in water)MW-MW-MW-MW-MW-Depth BelowTop of Casing(ft)MW-MW-MW-MW-MW-MW-MW-MW-Depth to groundwater 20 minutes post-AFVR/EFRWeather: MW-Depth to free product pre-AFVR/EFR
Site: 16800 30830 30900 30930 301000 301030 301100 301130 301200 301230 301300 301330 301400 301430 301500 301530 301600 30PPMmea = Measured VOC concentration from OVA/TVA (PPMv)Total emissions, poundsVelocity = Measured velocity (fpm)Total emissions, gallons (6.25 lb/gal)Temp = Measured temperature (0F)RH = Measured relative humidity (%)Flow = Actual Flow Volume (cfm)Specific Humidity = data from psychrometric chart at measured Temp and RH (lb water/lb dry air) (lbW / lbDA)Water Vapor = % water vapor on a volume basis = (Specific Humidity / 18 lb-mole H2O) / [(1 / 28.84 lb-mole dry air) + (Specific Humidity / 18 lb-mole H2O)]Qstd = Flow volume on a dry basis at a standard temperature of 680 F = (1-Water Vapor) (Flow) [528 0R / (Temp +460)]Dry Conc = PPMv VOC on a dry basis = [PPMmea / (1-Water Vapor)]Response Factor of OVA/TVA meter; 1 if response factor is unknownCorrected Conc = Dry Conc PPMv VOC corrected by Response Factor = (Dry Conc) (Response Factor) Mass Conc (mg/m3) = Mass concentration VOC as gasoline dry basis at standard temperature = (Corrected Conc) (128 mg/mg-mole / 24.07 m3/mg-mole)Mass Conc (lb/ft3) = [Mass Conc (mg/m3)] [(6.243 * 10-8)(lb/ft3)/(mg/m3)] Mass Removed (lb) = [Mass Conc (lb/ft3)] [Qstd (dscfm)] [Time Interval (min)] 584 0.000036 0.390.100 0.138 353 110 1 1101 111 591 0.000037 0.3694.7 2748 235.0 1.5 5391 112 59795.8 2524 235.0 1.4 495 0.100 0.1382845 235.0 1.8 558 0.100 0.138Job#0.138 499 2931 0.000183Response Factor:Response FactorMeters: MiniRae 2000-10.6 eV PID, TESTO 445-Vane, %RH, Temp DryConc(PPMv)Temp(0 F)RH(%)SpecificHumidity(lbW / lbDA)Circle K Stores, Inc./Circle K 2723970, 225 Cleveland Ave, Kings Mountain, NCMass Conc(mg/m3)475.0 3450 157.0 9.0 551PPMmea(PPMv)PostcarbonCorrected Conc(PPMv)0.1000.1001 551677111366790.138AFVR Data Sheet - Emissions Data & CalculationClient: ATC Group Services LLCTechnician: Water Vapor(vol %)Qstd(dscfm)PPMmea(PPMv)Pre-carbonVelocity(fpm)Flow(cfm)Stack Dia(in):Mass Removed (lb)5840.1000.1000.1000.1000.1006146156145760.1380.1383663673593543636171150.138112324 1117677781120.138 111111108.0104.0128.098.288.465.0117.098.73.01.9234.0230.034603132312931453129236.030512975205.0205.0221.0229.029351.4230.01.41.51.61.5232.01.45992.70.1380.1004033770.1000.1380.1380.1380.1380.1384654214104083953850.1381211211491141031111491030.000049 0.621257564279060654510.47Mass Conc(lb/ft3)0.560.0000402.740.1005585465375530.1000.100232.0230.0234.01.31.31.80.100284527822738281765.966.367.596.696.8114 0.000038407 0.00002575 0.000025112 596 0.0000370.000034 0.42136 0.000045 0.547220.28115 0.000038 0.43609125 0.000042 0.496667678 416 0.000026 0.2877 409 0.000026 0.281.436-Sep-178.950.400.000037 0.410.29401Time (h:m)Delta Time(min)96.4 2753 235.0 1.7 540