WS-9764_44962_CA_FPR_20221031

FREE PRODUCT RECOVERY REPORT

HUFFMAN MILL BP
1103 HUFFMAN MILL ROAD
BURLINGTON, NORTH CAROLINA
INCIDENT NO. 44962

PREPARED FOR:
MR. MICHAEL TOMPKINS
MCLEOD OIL COMPANY, INC.
PO BOX 100
MEBANE, NORTH CAROLINA 27302

PREPARED BY:
PILOT GEOLOGICAL, PLLC
PO BOX 128
KERNERSVILLE, NORTH CAROLINA 27285

OCTOBER 31, 2022
PILOT PROJECT NO. G-5930.4

SITE INFORMATION

Site Name and Location Huffman Mill BP
1103 Huffman Mill Road
Burlington, North Carolina

Incident No. 44962

Facility ID: 00-0-0000023461

Latitude and Longitude: 36 03’ 58.32”N; 79 30’ 00.43”W

Land Use Category: Commercial
Contacts
Owner of UST: Mr. Michael Tompkins
McLeod Oil Company, Inc.
PO Box 100
Mebane, North Carolina 27302
[phone]

Primary Contact: Mr. Michael Tompkins
McLeod Oil Company, Inc.
[phone]

Consultant: Pilot Geological, PLLC
PO Box 128
Kernersville, North Carolina 27285
[phone]

Contractor: Evo Corporation
1703 Vargrave Street
Winston Salem, North Carolina 27107
[phone]

Release Information: Laboratory analysis of a soil sample (S-1) collected on September 18, 2017
by others detected gasoline range TPH above the NC Action Level in the vicinity of the
northeastern dispenser. The estimated quantity of the release is unknown. Free product was not
reported to have been identified.

Table of Contents
1.0 SITE HISTORY ................................................................................................................... 1
1.1 UST Information ......................................................................................................................................... 1
2.0 SITE GEOLOGY AND HYDROGEOLOGY ............................................................................... 1
3.0 FIELD ACTIVITIES .............................................................................................................. 2
4.0 CONCLUSIONS ................................................................................................................. 3
5.0 RECOMMENDATIONS ....................................................................................................... 3
6.0 QUALIFICATIONS OF REPORT ........................................................................................... 3

DRAWINGS

Drawing 1 USGS Topographic Map
Drawing 2 Site Map
Drawing 3 Monitoring Well Location Map

TABLES

Table 1 UST Information
Table 2 Monitoring Well Construction Information
Table 3 Summary of Groundwater Analytical Results
Table 4 Summary of Aggressive Fluid Vapor Recovery
Table 5 Cumulative Volume of LNAPL Recovered
Table 6 Aggressive Fluid Vapor Recovery Data
Table 7 Emissions Calculations

APPENDIX

Non-Hazardous Materials Manifest & AFVR Data Sheet

Free Product Recovery Report
Huffman Mill BP
Pilot Project G-5930.4
October 31, 2022
1

1.0 SITE HISTORY

The site is located at 1103 Huffman Mill Road in Burlington, North Carolina (Drawings 1 and 2). The
site is currently developed with an active gasoline station. Pilot was requested to provide Limited
Site Assessment (LSA) services related to the Notice of Regulatory Requirements (NORR) issued
by the North Carolina Department of Environmental Quality (NCDEQ) dated June 17, 2020. A
release was previously identified by others in the vicinity of the northeastern dispenser.

Pilot previously completed a LSA dated July 21, 2020. Based on the findings of the LSA, the
NCDEQ issued a NORR dated October 19, 2020 requiring that an Additional Risk Assessment
Report (ARA) be completed.

Pilot previously completed an Additional Risk Assessment Report (ARA) dated February 17, 2021.
Based on the findings of the ARA, the NCDEQ issued a NORR dated March 26, 2021 requiring that
a CSA be completed. The ARA assessment indicated that the extent of the impacted groundwater
was not reasonably defined. The concentrations of benzene detected in monitoring wells MW-3
and MW-4 exceeded its GCL.

Pilot completed a CSA dated June 7, 2021. Based on the findings of the CSA, the NCDEQ issued a
NORR dated August 19, 2022 requiring semi-annual groundwater monitoring events to
determine if monitored natural attenuation is feasible.

Pilot completed a Groundwater Monitoring Report dated September 20, 2022. Based on the
findings of the groundwater monitoring event and the presence of free-product, the NCDEQ
approved free-product recovery by Aggressive Fluid and Vapor Recovery (AFVR).

Project information is based on correspondence between NCDEQ personnel, McLeod Oil Company,
Inc. and Pilot and the previously completed activities.

1.1 UST Information

A suspected release was identified during a previous assessment by others. Laboratory analysis
of a soil sample (S-1) collected on September 18, 2017 detected gasoline range TPH above the
NC Action Level in the vicinity of the northeastern dispenser. UST information is summarized in
Table 1.

2.0 SITE GEOLOGY AND HYDROGEOLOGY

The United States Geological Survey (USGS) Topographic Map, Gibsonville and Burlington, North
Carolina Quadrangles depict a structure on the site. Elevations on the site range from
approximately 652 feet above mean sea level on the northeastern portion of the site to
approximately 659 feet above mean sea level on the southwestern portion of the site. Gum
Creek is depicted approximately 1,890 feet east of the site. Based on the review of the USGS
Free Product Recovery Report
Huffman Mill BP
Pilot Project G-5930.4
October 31, 2022
2

topographic map and observations of the general area and site topography, surface run-off
would be expected to flow generally to the southeast across the site.

The subject site is located within the Piedmont Physiographic Province. The Piedmont
Physiographic Province generally consists of hills and ridges which are dissected by a system of
swales and streams. The Piedmont Physiographic Province is predominantly underlain by
metamorphic rock (formed by heat, pressure and/or chemical action) and igneous rock (formed
directly from molten material). The topography and relief of the Piedmont Province has
developed from differential weathering of the igneous and metamorphic rock. Ridges and hills
have been developed in areas of less weathered rock. Because of the continued chemical and
physical weathering, rock in the Piedmont Physiographic Province is generally covered with a
mantle of soil that has weathered in place from the parent bedrock. These soils vary in thickness
and are referred to as residuum or residual soils. The residuum is typically finer grained and has
higher clay content near the surface because of the advanced weathering. Similarly, the soils
typically become coarser grained with increasing depth because of decreased weathering. As the
weathering decreases, the residual soils generally retain the overall appearance, texture and
foliations of the parent rock.

In general, groundwater movement in the Piedmont Physiographic Province is from higher to
lower elevations. As such, the presumed direction of groundwater flow is generally to the
southeast across the site. Based on the presumed groundwater flow direction, areas
immediately west are potentially up-gradient of the site.

Soils at the site consist of sandy clay from the ground surface to approximately 15 feet bgs and
silty clay from approximately 15 feet bgs to 75 feet bgs.

3.0 FIELD ACTIVITIES

On October 17, 2022, Pilot completed an AFVR event for the site. The field activities were
completed by Pilot and EVO Corporation. Monitoring wells MW-3 and MW-5 (Drawing 3) were
utilized as extraction points during the AFVR event. The AFVR event consisted of using a vacuum
truck to remove free product, dissolved phase contamination and associated vapors. The amount
of product in MW-3 and MW-5 was measured prior to and subsequent to the AFVR event.
Approximately 2.58 feet of free product was measured in monitoring well MW-3 prior to the
AFVR event. Approximately 1.51 feet of free product was measured in monitoring well MW-5
prior to the AFVR event. Monitoring well construction information and a summary of historical
groundwater analytical results are included as Tables 2 and 3, respectively.

Based on the presence of free product in monitoring well MW-3 and MW-5, both of these wells
were utilized for the AFVR. Approximately 33 feet of stinger pipe was placed in MW-3, which
extended to approximately 2 feet below the initial oil/water interface or static water level.
Approximately 29 feet of stinger pipe was placed in MW-5, which extended to approximately 0.5
feet below the initial oil/water interface or static water level. The event was conducted for
Free Product Recovery Report
Huffman Mill BP
Pilot Project G-5930.4
October 31, 2022
3

approximately 8 hours from 8:20 am to 4:20 pm.

The average pumping rate over the course of this AFVR event was estimated to be approximately
0.64 gallons per minute. The total amount of product/groundwater recovered was estimated to
be 310 gallons, with approximately 5 gallons of which appeared to be free phase petroleum
product floating in the tank. The average vacuum during the event was 22 inches of Hg.

During the course of the event Pilot and EVO measured a series of exhaust parameters including
temperature; velocity; relative humidity; and photoionization (PID) measurements at
approximate half hour intervals in order to estimate the total amount of product recovered and
ultimately discharged as exhaust emissions. Based on the data collected and calculations,
approximately 623.51 pounds of total VOC emissions were generated during this event.
Approximately 104.76 gallons of gasoline were removed as liquid and emissions as a result of this
AFVR event. The recorded measurements and calculations are included in Tables 4 through 7.
The Non-Hazardous Materials Manifest and the AFVR Data Sheet are included in the Appendix.

4.0 CONCLUSIONS

A total of 310 gallons of liquids were extracted from monitoring wells MW-3 and MW-5 during
the AFVR event with approximately 5 gallons of which appeared to be free phase petroleum
product. Based on the data collected and calculations, approximately 623.51 pounds of total
VOC emissions were generated during this event. Approximately 104.76 gallons of gasoline were
removed as liquid and emissions a result of this AFVR event.

5.0 RECOMMENDATIONS

Pilot recommends that the current property owner/responsible party submit a copy of this Free
Product Recovery Report to the NCDEQ, UST Section for their review.

6.0 QUALIFICATIONS OF REPORT

The activities and evaluative approaches used in this assessment are consistent with those
normally employed in remediation projects of this type. Our evaluation of site conditions has
been based on our understanding of the site project information and the data obtained during
our field activities.

DRAWINGS
SITE
USGS Topographic Map
Huffman Mill BP
1103 Huffman Mill Road
Burlington, Alamance County, NC
Pilot Project G-5930.4
Drawing 1
USGS Topographic Map
Gibsonville and Burlington, NC
Quadrangles
Scale: 1” = 2,000’
LEGEND
Site Boundary
Site Map
Huffman Mill BP
1103 Huffman Mill Road
Burlington, Alamance County, NC
Pilot Project G-5930.4
Drawing 2
Google Earth
Interactive Mapping Software
Scale : 1”= 100’
LEGEND
Site BoundaryU. UST System
U
Monitoring Well Location Map
Huffman Mill BP
1103 Huffman Mill Road
Burlington, Alamance County, NC
Pilot Project G-5930.4
Drawing 3
Google Earth
Interactive Mapping Software
Scale : 1”= 60’
LEGEND
Site Boundary
Monitoring Well Location
MW-2
MW-8
MW-4DW-1
MW-7
MW-6
MW-9
MW-1
MW-3
MW-5

TABLES
UST ID NumberOwner Last ContentsPrevious ContentsCapacity (in Gallons)Construction DetailsTank DimensionsInstallation DateStatus Release3Gasoline Gasoline 8,000 Single Wall Steel8,000 Single Wall Steel Unknown 5/1/1986NoActive NoUnknown 5/1/1986 ActiveTable 1 - UST InformationHuffman Mill BPBurlington, North Carolina1McLeod Oil Company, Inc. PO Box 100 Mebane, North Carolina 27302Gasoline Gasoline 8,000 Single Wall Steel Unknown 5/1/1986 Active No2Gasoline Gasoline
Monitoring Well IDDate Installed Elevation (TOC)Static Water Level (9/9/2022)Groundwater ElevationTotal Depth Screened Interval (feet) Sand IntervalBentonite IntervalMW-1 2/22/2018 100.00 28.21 71.79 40 20-40 18-40 16-18MW-2 1/12/2021 100.45 28.32 72.13 35 15-35 13-35 4-13MW-3** 1/12/2021 100.29 30.50 71.96 35 15-35 13-35 4-13MW-4 1/12/2021 99.36 28.24 71.12 35 15-35 13-35 4-13MW-5*** 5/5/2021 100.15 FP FP 30 15-30 13-30 4-13MW-6 5/5/2021 98.75 27.88 70.87 30 15-30 13-30 4-13MW-7 5/5/2021 98.45 27.59 70.86 30 15-30 13-30 4-13MW-8 11/3/2021 97.67 26.95 70.72 30 15-30 13-30 4-13MW-9 11/3/2021 96.70 27.83 68.87 30 15-30 13-30 4-13DW-1 1/12/2021 99.91 28.42 71.49 75 70-75 68-75 4-68***Free product detected to the bottom of the wellTable 2 - Monitoring Well Construction InformationHuffman Mill BPBurlington, North CarolinaMW-1 was utilized as an arbitrary benchmark with assumed elevation of 100.00 feet above msl.**If free product is present the groundwater elevation is calculated by (TOC Elevation - Static) + (free product thickness x 0.8581)
Sample IDApproximate Water Level (ft. BGS)Groundwater Elevation (ft.)Sample Collection DateTert-Amyl AlcoholBenzenen-Butylbenzenesec-Butylbenzene1,2-DichloroethaneDiisopropyl EtherEthylbenzeneIsopropylbenzeneMTBENaphthaleneN-PropylbenzeneStyreneToluene1,2,4-Trimethylbenzene1,3,5-TrimethylbenzeneTotal XylenesEDB1,2,3-TrichloropropaneLeadC5-C8 AliphaticsC9-C12 AliphaticsC9-C10 Aromatics23.28 76.72 7/2/2020 NA4,250BQL BQL BQL BQL2,780BQL BQL548 318ND8,070 2,470 605 11,560BQL BQL6.58 51,800 52,600 15,00022.66 77.34 1/18/20217,660 4,020ND ND ND ND2,000 76.7 673 462ND ND6,040 1,660ND7,760NA NA NA NA NA NA21.35 78.65 5/6/2021 NA4,330ND ND ND ND2,760 117 617 630ND ND7,810 2,610ND11,190NA NA NA NA NA NA28.21 71.79 9/9/20225,170 2,550ND ND ND ND421 97.0 222 383 200ND448 874 243 3,920NA NA NA NA NA NA22.70 77.75 1/18/20211,360 467ND ND ND ND298 48.7ND25.8ND ND601 825 278 1,910ND ND8.1 7,520 10,400 3,43021.34 79.11 5/6/2021 NA854ND ND ND ND576 50.0 79.8 92.8ND ND1,150 1,150 348 3,189NA NA NA NA NA NA28.32 72.13 9/9/2022464 212 14.4ND ND ND27.4 9.3ND ND15.9ND59.6 227 72.6 616NA NA NA NA NA NA22.85 77.44 1/18/202125,700 5,360ND ND ND ND3,540ND558 644ND ND32,200 2,730ND18,180ND ND6.5 196,000 147,000 8,12021.60 78.69 5/6/2021 NA6,670ND ND ND ND3,380ND617 696ND ND33,000 2,580ND17,130NA NA NA NA NA NA28.24 71.96 9/9/202222.74 76.62 1/18/202125,000 9,100ND ND ND ND3,250ND7,530 679ND ND29,900 2,340ND15,150ND ND7.3 142,000 57,900 16,60021.55 77.81 5/6/2021 NA11,700ND ND ND ND3,300ND7,980 735ND ND33,800 2,430ND15,930NA NA NA NA NA NA28.24 71.12 9/9/202226,400 8,470ND ND ND ND3,450 132 6,420 702 414 122 24,800 2,940 751 16,470NA NA NA NA NA NA22.21 77.94 5/6/2021 NA13,700ND ND ND245 3,650ND843 703ND45,600 2,510ND18,610ND ND ND299,000 51,600 7,530FP FP 9/9/202221.41 77.34 5/6/2021 NA1,320 17.5 8.4 10.8 108 37.6 60.9 995 138 26.1ND36.4ND ND21.3ND0.67ND11,100 584 45127.88 70.87 9/9/20224,100 1,280ND ND ND99.8 10.6 66.6 1,970 84.2 25.1ND35.4ND ND ND NA NA NA NA NA NA21.90 76.55 5/6/2021 NA2,610ND ND ND ND2,820 136 178 663ND ND7,500 3,160ND12,750ND ND ND80,700 50,700 11,20027.59 70.86 9/9/2022 ND3,820 103ND ND ND2,100 125 274 321 454ND5,900 2,890 747 9,440NA NA NA NA NA NA24.65 73.02 11/8/2021 ND1,590ND ND ND ND1,020 86.3ND431 247ND3,680 2,060 505 7,760ND ND7.1 13,000ND8,20026.95 70.72 9/9/2022 ND3,020 61.4ND ND ND872 63.8ND329 155ND4,360 1,440 349 7,820NA NA NA NA NA NA25.61 71.09 11/8/2021 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND5.8ND ND ND27.83 68.87 9/9/2022 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND NA NA NA NA NA NA22.80 77.11 1/18/20211,270 628ND ND ND ND204 19.6 94.7 58.1ND ND527 369ND1,044ND ND ND8,260 5,390 1,82021.58 78.33 5/6/2021 NA226ND ND ND ND1.9ND44.4ND ND ND57.9ND25.6 154.6NA NA NA NA NA NA28.42 71.49 9/9/2022305 39.7 0.91ND ND ND7.8 0.84 16.0ND1.0ND22.4 13.9 10.2 101.0NA NA NA NA NA NA40 1 70 70 0.4 70 600 70 20 6 70 70 600 400 400 500 0.02 0.005 15 400 700 20040,000 5,000 5,900 8,800 400 70,000 80,000 30,500 20,000 6,000 26,100 70,000 260,000 28,500 24,100 50,000 50 NS 15,000 NS NS NS= Concentration Exceeds the 2L Standard= Concentration Exceeds the GCLppb = Parts Per BillionBGS = Below Ground SurfaceN/A = Not ApplicableNS = No StandardBQL = Below Quantitation LimitsND = Not DetectedFP = Free ProductFP - 1.91'FP - 2.53'MW-5MW-9MW-8MW-7MW-6NC 2L Standard (ppb)GCLs (ppb)Table 3 - Summary of Groundwater Analytical ResultsHuffman Mill BPBurlington, North CarolinaTargeted CompoundsVPH 6200BStandardsMW-1MW-2MW-3MW-4DW-1504.1
MW-3 Gasoline AFVR 2.58 0.00MW-5 Gasoline AFVR 1.51 0.00* Bailing, Skimming, Aggressive Fluid Vapor Recovery, Mobile Multiphase Extraction, etc.Table 4 - Summary of Aggressive Fluid Vapor RecoveryHuffman Mill BPBurlington, North CarolinaDate Well ID #Product Type (gasoline, diesel, etc.)NAPL Recovery Method*Product Thickness before Recovery (feet)Product Thickness after Recovery (feet)Amount of Vaporized Product (gallons)Amount of Liquid (Water + Product) (gallons)Amount of Liquid Product (gallons)Cost of Event10/17/202299.76 310 ~5 $3,262.50
Date of Recovery Event (m/dd/yy)Total Volume (Liquid and Vapor) Recovered from Site During Current Recovery Event (gallons)Cumulative Total of Volume Recovered to Date from All Recovery Events (gallons) 10/17/2022409.76409.76Table 5 - Cummulative Volume of LNAPL RecoveredHuffman Mill BPBurlington, North Carolina
10/17/20228:20MW-3 & MW-5226426881000.029866.681775186/24/20228:50MW-3 & MW-52240561101000.060639.158147376/24/20229:20MW-3 & MW-52270361201000.083265.191856556/24/20229:50MW-3 & MW-52278961281000.107070.297931976/24/202210:20MW-3 & MW-52278561231000.091571.765786166/24/202210:50MW-3 & MW-52253561301000.114047.133197746/24/202211:20MW-3 & MW-52267761281000.107060.319011346/24/202211:50MW-3 & MW-52257561351000.133649.120268916/24/202212:20MW-3 & MW-52255061311000.117748.170693746/24/202212:50MW-3 & MW-52256561341000.129548.576049386/24/202213:20MW-3 & MW-52285861411000.162070.185637276/24/202213:50MW-3 & MW-52250461311000.117744.141872086/24/202214:20MW-3 & MW-52239761241000.094436.116485846/24/202214:50MW-3 & MW-52246661351000.133639.808774456/24/202215:20MW-3 & MW-52239261331000.125433.918158076/24/202215:50MW-3 & MW-52252261321000.121445.449740546/24/202216:20MW-3 & MW-52259561371000.142450.14398213Averages -- -- 22 585.88235 -- 127.0588235 100 0.110047059 52.12819816Relative Humidity (%)Water Vapor % (Humidty Ratio)Qstd (flow)Table 6 - Aggressive Fluid Vapor Recovery DataHuffman Mill BPBurlington, North CarolinaDate Time (24 hr)Monitoring Wells UtilizedVacuum (Inches of Hg)Velocity (ft/min)Exhaust Pipe ID (in)Temp (F)
30 66.68177518 320 1 320 1,701.70 0.000106237 4.75 2.3760 39.15814737 160 1 160 850.85 0.000053119 2.37 2.3790 65.19185655 168 1 168 893.39 0.000055775 2.49 2.49120 70.29793197 359 1 359 1,909.10 0.000119185 5.33 5.33150 71.76578616 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22180 47.13319774 371 1 371 1,972.91 0.000123169 5.51 5.51210 60.31901134 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22240 49.12026891 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22270 48.17069374 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22300 48.57604938 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22330 70.18563727 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22360 44.14187208 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22390 36.11648584 325 1 325 1,728.29 0.000107897 4.82 4.82420 39.80877445 215 1 215 1,143.33 0.000071378 3.19 3.19450 33.91815807 5,000 1 5,000 26,589.13 0.001659960 74.22 74.22480 45.44974054 248 1 248 1,318.82 0.000082334 3.68 3.68Averages 52.25221166 2,635 1 2,635 14,014.46 0.000874923 39.12 38.97623.51Notes:K = Number of carbons in the calibration gas: (methane K = 1, Propane K = 3, or Hexane K= 6) PPMg = PPMv, Volumetric concentration as gasoline emission, dry basis at STPCg:m + mg/dsm3, mass concentration of gasoline emission, dry basis at STPMg = 128 mg/mg-mole, molecular weight of gasoline (this value may vary depending on contaminant)K3 = 24.07 dsm3/1E+6 mg-mole, mass to volume conversion factor at STPCg = lb/dcsf, mass concentration of gasoline emission, dry basis at STPPMRg = lb/hr, pollutant mass removal rate of gasoline emissionPMR = pollutant mass removal of gasoline emission over timeEquations:PPMg = PPM measured * KCg:m = PPMg * (Mg/K3)Cg = Cg:m * 62.43E-09 lb-m3/mg-ft3PMRg = Cg * Qstd * 60 min/hrPMR = PMRg * ((T2 - T1) / 60)PMRg (lb/hr) PMR (lb)Total Emissions (lbs)Table 7 - Emission CalculationsHuffman Mill BPBurlington, North CarolinaElapsed Time (min)Qstd (flow)PID Reading (ppm)K (#C-gas)PPMgCg:m (mg/dsm3)Cg (lb/dscf)

APPENDIX