WS-29484_48624_CA_LTRRPT_20230116_AFVR

2725 E. Millbrook Road, Suite 121
Raleigh, North Carolina 27604
Telephone [phone]
Fax [phone]
www.oneatlas.com

January 16, 2023

Mr. Ryan Bond
North Carolina Department of Environmental Quality
Winston-Salem Regional Office
Division of Waste Management - UST Section
450 West Hanes Mill Road, Suite 300
Winston-Salem, North Carolina 27105

Re: LNAPL Recovery Letter Report
Circle K Store #2723154
11315 N. Main Street
Archdale, Randolph County, North Carolina
NCDEQ Incident No. 48624

Dear Mr. Bond:

ATC Associates of North Carolina, P.C. (ATC), on behalf of Circle K Stores, Inc., is submitting this letter
report to document the results of the Aggressive Fluid Vapor Recovery (AFVR) event that was conducted at
the facility and pre-approved in task authorization TA-1. The site location is provided in Figure 1 and a site
map is provided as Figure 2.

AFVR Event
On December 7, 2022, ATC supervised the performance of an AFVR event at the site to assist in light
non-aqueous phase liquid (LNAPL) recovery. Prior to the initiation of AFVR activities, depths to LNAPL
and groundwater were measured in wells OW-3 and MW-5. LNAPL was measured in well OW-3 at a
thickness of 0.10 feet. The AFVR event included a simultaneous connection to wells OW-3 and MW-5 for
a 480-minute period.

A stinger pipe consisting of one-inch flexible hose was used to connect between the truck vacuum line and
each of the wells. The stinger pipes in well OW-3 and MW-5 were lowered to an approximate depth of 14
feet below ground surface (bgs). The stinger pipes were not adjusted during the event. The annuli between
the stinger pipe assemblies and the well casings were sealed to minimize vacuum loss. AFVR activities
were initiated at 0830 hours with a simultaneous connection to wells OW-3 and MW-5. At 1630 hours, the
AFVR event concluded.

Throughout the AFVR event, operative parameters from the exhaust stack on the vacuum truck were
measured at 15-minute intervals for the first two hours and at 30-minute intervals for the remaining six
hours. Using a photoionization detector (PID), total volatile organic compound (VOC) readings from the
exhaust stack ranged from 1,879 parts per million (ppm) to greater than 15,000 ppm during the event. The
truck vacuum gauge reading registered between 18 and 20 inches of mercury throughout the event.

During the AFVR event, a total of 455 gallons of LNAPL and petroleum-impacted groundwater was
recovered. A sheen was noted in the vacuum truck tank. A copy of the vacuum truck specification is
included in Attachment I. Eastern Environmental Management, LLC of Rocky Mount, North Carolina
disposed of the recovered fluid. The disposal manifest is included in Attachment I.

Using the PID readings of the exhaust stack, air emission calculations indicated approximately 588.80
pounds (110.85331 gallons) of petroleum vapors were emitted through the exhaust stack. AFVR field
measurements and emissions calculations are provided in Table 1.
fiffi January 16,2023
Page 2 of 2
On January 4,2023, ATC measured wells MW-l through MW-5 and OW-l through OW-3 forthe presence
of LNAPL. On this date, LNAPL was not measured in any site monitoring or observation wells.
ATC recommends the continuation of weekly site visits to monitor the nearby surface water and to measure
for the potential presence of LNAPL in the site monitoring and observation wells until the product lines are
replaced.
If you have any questions or require additional information, please contact our office at [phone].
Mr. Alan Cubberley, Circle K Stores, Inc.
ATC Associates of North
Maureen Jackson, P.G.
Senior Project Manager
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TABLES

TABLE 1
AFVR DATA AND EMISSIONS CALCULATIONS (12/7/22 EVENT)
CIRCLE K STORE #2723154
11315 N. MAIN STREET
ARCHDALE, RANDOLPH COUNTY, NORTH CAROLINA
NCDEQ INCIDENT NO. 48624
AGGRESSIVE FLUID VAPOR RECOVERY EVENT
SITE NAME: Circle K Store #2723154
INCIDENT NUMBER: 48624
AVERAGE DEPTH TO GROUNDWATER: Approximately 5-10 feet
IDENTIFY THE WELL AND THE I.D. OF EACH WELL USED FOR AFVR: MW-5 and OW-3
PROVIDE BLOWER SPECIFICATIONS OF THE VACUUM TRUCK (cfm @ in Hg): 434cfm @ 24in Hg
DRY STANDARD CUBIC FEET PER MINUTE (DSCFM) AIR FLOW CALCULATIONS (Qstd)
Date Time Vacuum Velocity Pipe ID Temp Rel Humid Water Qstd PPM T (K)Ps (Pa)Pv (Pa)
(inches of Hg)(ft/min)(in)(°F)(%)Vapor (%)(flow)(measured)
12/7/2022 8:30
12/7/2022 8:30 -19 109 6 92.2 100 3.30E-04 20 2175 306.44 5110.2 5.11E+03
12/7/2022 8:45 -19 257 6 95.8 100 3.71E-04 46 1879 308.44 5710.9 5.71E+03
12/7/2022 9:00 -20 296 6 93.6 100 3.46E-04 54 14399 307.22 5336.9 5.34E+03
12/7/2022 9:15 -19 219 6 99.0 100 4.12E-04 39 >15000 310.22 6295.4 6.30E+03
12/7/2022 9:30 -20 237 6 106.8 100 5.29E-04 41 >15000 314.56 7941.4 7.94E+03
12/7/2022 9:45 -20 228 6 104.3 100 4.88E-04 40 >15000 313.17 7377.5 7.38E+03
12/7/2022 10:00 -19 236 6 103.4 100 4.75E-04 41 >15000 312.67 7183.2 7.18E+03
12/7/2022 10:15 -18 239 6 105.6 100 5.09E-04 42 >15000 313.89 7666.2 7.67E+03
12/7/2022 10:30 -18 225 6 104.4 100 4.90E-04 39 >15000 313.22 7399.4 7.40E+03
12/7/2022 11:00 -20 239 6 106.7 100 5.27E-04 41 >15000 314.50 7918.1 7.92E+03
12/7/2022 11:30 -20 228 6 105.6 100 5.09E-04 40 >15000 313.89 7666.2 7.67E+03
12/7/2022 12:00 -19 230 6 104.3 100 4.88E-04 40 >15000 313.17 7377.5 7.38E+03
12/7/2022 12:30 -19 221 6 105.1 100 5.01E-04 39 >15000 313.61 7554.0 7.55E+03
12/7/2022 13:00 -19 216 6 103.5 100 4.76E-04 38 >15000 312.72 7204.5 7.20E+03
12/7/2022 13:30 -19 229 6 104.1 100 4.85E-04 40 >15000 313.06 7333.9 7.33E+03
12/7/2022 14:00 -20 230 6 105.3 100 5.04E-04 40 >15000 313.72 7598.8 7.60E+03
12/7/2022 14:30 -19 239 6 103.8 100 4.81E-04 42 >15000 312.89 7269.0 7.27E+03
12/7/2022 15:00 -19 227 6 104.5 100 4.91E-04 40 >15000 313.28 7421.3 7.42E+03
12/7/2022 15:30 -19 218 6 103.1 100 4.70E-04 38 >15000 312.50 7119.4 7.12E+03
12/7/2022 16:00 -19 222 6 104.8 100 4.96E-04 39 >15000 313.44 7487.4 7.49E+03
12/7/2022 16:30 -19 230 6 106.1 100 5.17E-04 40 >15000 314.17 7779.9 7.78E+03
NOTES
Qstd = Flow at DSCFM
Vacuum = The level of vacuum being applied should be recorded from the vacuum truck tank (inches of Hg)
Velocity = The rate at which air flows is measured at the blower discharge piping (anemometer or pitot tube)
Pipe ID = The inside diameter of the blower discharge piping (from the vacuum truck)
Temperature = The temperature of the air stream exiting the blower discharge piping (dry bulb temp., in deg.°F)
Relative humidity = The % relative humidity of the air stream exiting the blower discharge piping
Water Vapor in % = Pounds of water per pound of dry air, derived from the Psychrometric chart (temp Vs relative humidity)
* The first hour of velocity, temp, and rel humid readings are an average due to malfunctioning equipment.
EQUATION
Qstd = (1-Water Vapor) * velocity * (PI * (diameter/24)^2) * (528°R/(Temp + 460))
Stingers in wells OW-3 and MW-5 set at 14 feet bgs
TABLE 1
AFVR DATA AND EMISSIONS CALCULATIONS (12/7/22 EVENT)
CIRCLE K STORE #2723154
11315 N. MAIN STREET
ARCHDALE, RANDOLPH COUNTY, NORTH CAROLINA
NCDEQ INCIDENT NO. 48624
EMISSION CALCULATIONS
Elapsed
Time Flow Cg:m Cg PMRg PMR
(min)(DSCFM)(ppm)(#C - gas)(mg/dsm^3)(lb/dscf)(lb/hr)(lb)
0 20 2175 4 8700 46265 0.002888 3.43 4.29
15 46 1879 4 7516 306285 0.019121 61.40 15.35
30 54 14399 4 57596 425426 0.026559 62.06 15.51
45 39 20000 4 80000 425426 0.026559 65.43 16.36
60 41 20000 4 80000 425426 0.026559 65.43 16.36
75 40 20000 4 80000 425426 0.026559 63.49 15.87
90 41 20000 4 80000 425426 0.026559 65.92 16.48
105 42 20000 4 80000 425426 0.026559 66.26 16.56
120 39 20000 4 80000 425426 0.026559 62.63 31.32
150 41 20000 4 80000 425426 0.026559 66.00 33.00
180 40 20000 4 80000 425426 0.026559 63.21 31.60
210 40 20000 4 80000 425426 0.026559 64.05 32.02
240 39 20000 4 80000 425426 0.026559 61.37 30.69
270 38 20000 4 80000 425426 0.026559 60.31 30.16
300 40 20000 4 80000 425426 0.026559 63.81 31.91
330 40 20000 4 80000 425426 0.026559 63.83 31.91
360 42 20000 4 80000 425426 0.026559 66.67 33.33
390 40 20000 4 80000 425426 0.026559 63.17 31.58
420 38 20000 4 80000 425426 0.026559 60.95 60.95
450 39 20000 4 80000 425426 0.026559 61.71 61.71
480 40 20000 4 80000 425426 0.026559 63.65 31.83
510
Total emissions in pounds 588.80
NOTES
PPM measured = Actual measurements (ppm) taken with a OVA or TVA at the blower discharge piping
K = Number of carbons in calibration gas: (Methane K = 1, Propane K = 3, Isobutylene = 4, or Hexane K = 6)
PPMg = PPMv, Volumetric concentration as gasoline emission, dry basis at STP
Cg:m = mg/dsm3, mass concentration of gasoline emission
Mg = 128 mg/mg-mole, molecular weight of gasoline (this value may vary depending on contaminant)
K3 = 24.07 dsm^3/1E6 mg-mole, mass to volume conversion factor at STP
Cg = lb/dcsf, mass concentration of gasoline emission, dry basis at STP
PMRg = lb/hr, pollutant mass removal rate of gasoline emission
PMR = pollutant mass removal of gasoline emission over time
**PID readings were greater than 15,000 ppm so a conservative PID reading of 20,000 ppm was used. The actual ppm reading is not known.
Recovery:
455 Gallons total fluids
Sheen Gallons free product as a liquid
110.85331 Gallons of gasoline as vapor (assuming a specific density of 0.71 as a liquid)
PPM
measured K PPMg

FIGURES

MW-1OW-1MW-5MW-2MW-3MW-4OW-2OW-3STORM DRAINLEAK LOCATIONXSPILL FLOWUSTBASINCIRCLE K#2723154STORENORTH MAIN STREETTRINDALE ROAD= MONITORING WELL= OBSERVATION WELL

ATTACHMENT I