AS-3826_28946_CA_MMPE_20231121

WithersRavenel
Our People. Your Success.
115 MacKenan Drive | Cary, NC 27511
t: 919.469.3340 | f: 919.467.6008 | www.withersravenel.com | License No. F-1479
ASHEVILLE | CARY | CHARLOTTE | GREENSBORO |PITTSBORO | RALEIGH | SOUTHERN PINES | WILMINGTON

November 21, 2023

State of North Carolina Department of Environmental Quality Trust Fund Branch Division of Waste Management-Underground Storage Tank Section
1646 Mail Service Center
Raleigh, North Carolina 27699-1646 Attn: Mr. Scott Ryals, P.E. Re: Letter Report - MMPE
Antioch Food Mart 2940 NC Highway 18/US Highway 64 Morganton, Burke County, North Carolina Groundwater Incident Number: 28946
UST Number: AS-3826
WR Project Number: 23-0307-U Mr. Ryals,
WithersRavenel, Inc. (WR) has completed this Letter Report to document the Mobile Multi-Phase
Extraction (MMPE) event described in task authorization (TA) TA-01 for the above referenced site approved by the Federal & State Lead Program on August 29, 2023. The site location is depicted on Figure 1 and site features including monitoring well locations are depicted on Figure 2.
MMPE Event
WR personnel, along with Eastern Environmental Management, LLC (EEM) mobilized to the site on October 2, 2023 for the purposes of performing a 96-hour MMPE event. This event was initiated to reduce the light non-aqueous phase liquid (LNAPL) within wells MW-1, MW-5, and MW-6. In the performance of the MMPE, EEM connected to monitoring wells MW-1, MW-5, and
MW-6 and utilized vacuum extraction equipment mounted within an enclosed trailer. Fluids
recovered were contained in a 6,000-gallon (gal) tanker trailer.
WR gauged site monitoring wells prior to sampling as described above and performance of
remedial actions at the location. Gauging of groundwater elevations within wells MW-1, MW-5
and MW-6 indicated the following:
Well ID Depth to LNAPL Depth to Water Well Depth LNAPL Thickness
MW-1 32.40 32.50 35.0 0.10
MW-5 24.00 26.50 30.0 2.50
MW-6 32.30 35.60 40.0 3.30
[All measurements shown in feet (ft)]
WithersRavenel
Our People. Your Success.

Antioch Food Mart – NCDEQ Inc. #28946 WR Project # 23-0307-U Letter Report November 2023 2

In the completion of the MMPE activities, EEM installed 1-in dia PVC stingers into wells MW-1,
MW-5, and MW-6 at depths of approximately 0.5-ft beneath the measured groundwater
elevation. These stingers were plumbed at the surface to 2.0-in chemical resistant flexible hose,
which was connected to a vacuum trunk line servicing the vacuum/pressure regenerative blower
housed in the equipment trailer.
Following setup, the MMPE system was started and operated continuously for a period of 96-
hours to induce movement and recovery of total fluids from MW-1, MW-5, and MW-6. EEM
personnel monitored the performance of the MMPE system over the course of the event, adjusted
the stinger depths and optimized recovery as necessary.
In completion of the MMPE event, a total of 9,249-gal of fluids were recovered from MW-1, MW-3, and MW-4. Recovery included total emissions of 1,014.29 pounds or an estimated 162.29-gal of gasoline as emissions. On October 4, 2023, 5,280 gallons of petroleum contaminated
groundwater was then transported off-site for proper disposal at their facility in Rocky Mount, NC. On October 6, 2023, 3,969 gallons of petroleum contaminated groundwater was also transported offsite by EEM for proper disposal. The manifests and disposal document associated with disposal are included as attachments. Trace amounts of LNAPL present on the recovered groundwater in the tanker truck at the completion of the event.
Airflow rates during the MMPE event ranged from 380- to 401-feet per minute (fpm). System temperature ranged from 59- to 118-degrees Fahrenheit, and relative humidity was 100-percent. Monitoring of VOC emissions showed initial levels of 4,980 parts-per-million (ppm) decreasing to 1,261 ppm over the course of the event.
After completion of the MMPE event, EEM dismantled the MMPE setup at the location. WR
personnel gauged MW-1, MW-5, and MW-6 during the water recovery after removal of the stingers. No LNAPL was measured within the wells following completion of the MMPE event. Field notes and site photos for the October 2023 MMPE event are included as Attachment A while EEM documentation associated with the event are provided as Attachment B.
WR appreciates the opportunity to be of service to the Federal & State Lead Program. Should you
have any questions regarding the attached, please do not hesitate to contact us at [phone].
Cordially,
WithersRavenel

Flora D’Souza, CHMM
Environmental Project Scientist II
Elizabeth A. Allyn, P.G.
Environmental Project Geologist II

Enclosure(s): Figures Attachment A: Field Notes & Site Photographs Attachment B: EEM MMPE Documentation
WithersRavenel
Our People. Your Success.

FIGURES
CBM
LA
DRAWN BY:
9/20/21 23-0307-U
1
SUBJECT SITE
±6.6 ACRES
SCALE:FIGURE NO.:
PROJECT NO.:DATE:APPROVED BY:
ANTIOCH FOOD MART - NCDEQ INC. 28946
2940 US-64
MORGANTON, BURKE COUNTY, NC
GENERAL LOCATION MAP
1"=1000 '
GRAPHIC SCALE
1 inch = 1000 ft.
0 1000500 2000
WithersRavenel
Engineers | Planners | Surveyors
115 MacKenan Drive | Cary, NC 27511 | t: 919.469.3340 | license #: C-0832
www.withersravenel.com
MW-2
MW-1
MW-3 MW-6
MW-4
MW-5US HWY 64
A
N
T
I
O
C
H

R
D
16,000-GALLON
COMPARTMENTALIZED UST
DISPENSER
ISLAND
MW-9
MW-8
MW-7
WSW
(INACTIVE)
SITE
LEGEND
TYPE II MONITORING WELL LOCATION
WATER SUPPLY WELL
NOTES:
1.) AERIAL OBTAINED FROM THE LOCAL COUNTY GIS DEPARTMENT.
4020 80
CBM
LA
DRAWN BY:
1"=40 '
1/20/22 23-0307-U
1
SCALE:FIGURE NO.:
PROJECT NO.:DATE:APPROVED BY:
ANTIOCH FOOD MART - NCDEQ INC. 28946
2940 US-64MORGANTON, BURKE COUNTY, NC
SITE MAP
WithersRavenel
Engineers | Planners | Surveyors
115 MacKenan Drive | Cary, NC 27511 | t: 919.469.3340 | license #: F-1479www.withersravenel.com
WithersRavenel
Our People. Your Success.

ATTACHMENT A

FIELD NOTES & PHOTOGRAPHIC RECORD
WithersRavenel
Our People. Your Success.
Antioch Food Mart – NCDEQ Incident #28946 WR Project # 02172214.51 Subsequent Monitoring Report Photograph Dates: December 2021 and January 2022
PHOTO 1 View of site
PHOTO 2 Location of monitoring well MW-1
WithersRavenel
Our People. Your Success.
Antioch Food Mart – NCDEQ Incident #28946 WR Project # 02172214.51 Letter Report Photograph Dates: April 11 and 15, 2022
PHOTO 3 Location of monitoring well MW-5
PHOTO 4 Location of monitoring well MW-6
WithersRavenel
Our People. Your Success.

ATTACHMENT B EEM MMPE DOCUMENTATION