Long-Term Stewardship Assessment Report

Former ExxonMobil Manassas Terminal

EPA ID #: VAD048565279

Manassas, Virginia 20109

Assessment Date: September 9, 2019

Introduction: Long-term potential stewardship (LTS) refers to the activities necessary to ensure that
engineering controls (ECs) are maintained and that institutional controls (ICs) continue to be enforced.
The purpose of the Environmental Protection Agency (EPA) Region 3 LTS program is to periodically
assess the efficacy of the implemented remedies (i.e. ECs and ICs) and to update the community on
the status of Resource Conservation and Recovery Act (RCRA) Corrective Action facilities. The
assessment is conducted in twofold, which consists of a record review and a field inspection, to ensure
that the remedies are implemented and maintained in accordance to the final decision.

Facility Background: The Former Exxon Mobile Manassas Terminal facility occupies an
approximate 11-acre parcel located at 10315 Balls Ford Road Manassas, Virginia (Facility). The
Facility was purchased in 1965 by Mobil Oil Corporation (Mobil). From 1965 to 2000, the Facility
was owned and operated by Mobil. In 1999, Mobil changed its name to ExxonMobil Oil Corporation
(ExxonMobil). From 2000 to 2004, Tosco/ConocoPhillips (Tosco) owned and operated the Facility.
From 2004 through the present, Sunoco Marketing & Terminals, LP owned and operates the Facility
for bulk storage and distribution of gasoline.

The Facility is located within an industrial park located approximately 2.5 miles north of downtown
Manassas. The Facility is bordered to the north by Pomeroy Company facility, to the south by a
commercial building, to the east by the Transcontinental Gas Pipeline Company facility, and to the
west by the Interstate 66 Industrial Park and a private warehousing company. Security for the Facility
is provided by a chain-link fence and electronically operated gate.

Facility investigations began in 1990 to delineate groundwater contamination related to historical
gasoline releases. Based on sampling results benzene, toluene, ethylbenzene, xylenes (BTEX) and
methyl tert-butyl (MTBE) are the Facility-related Contaminants of Concern (COCs) in groundwater.
On October 11, 2000, a Facility Lead Agreement (FLA) between EPA and ExxonMobil was executed
in which the Facility acknowledged its understanding and acceptance of corrective action goals.
Interim measures were performed from 2004 - 2012. Remedial technologies included Vacuum Truck
Extraction (VTE) events and implementation of an in-situ Submerged Oxygen Curtain (iSOC®)
system at select groundwater monitoring wells.

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Current Site Status: On January 28, 2014, Virginia Department of Environmental Quality (VADEQ)
issued the Statement of Basis (SB) in which the final remedy was selected. The remedy consists of
VTE, monitored natural attenuation (MNA) until drinking water standards are met and compliance
with and maintenance of institutional controls. A Special Warrant Deed dated May 3, 2000 (Deed) in
placed on Facility property restricting land and groundwater use. Currently, the gasoline terminal is
operated by Sunoco LP.

Long-term Stewardship Site Visit: On September 9, 2019, EPA conducted a long-term stewardship
site visit with VADEQ and Facility representatives to discuss and assess the status of the implemented
remedies at the site.

The attendees were:

Name

Organization

Email Address

John Hopkins

EPA Region 3

hopkins.john@epa.gov

Kurt Kochan

Virginia Department of
Environmental Quality

kurt.kochan@deq.virginia.gov

Allyson Lackey

Virginia Department of
Environmental Quality

kari.lackev@deq.virginia.gov

Christina Archambeault

Virginia Department of
Environmental Quality

christina.archambeault@deq.virginia.gov

Regan O'Brien

ExxonMobil

regan.obrienl@exxonmobil.com

Mark Steele

Kleinfelder

mcsteele@kleinfelder.com

Institutional Controls (ICs) Status:

Consent Order. The selected remedy is being implemented and enforced by a Remedy Consent Order
agreed to by VADEQ and the Facility on September 9, 2014. The following ICs apply to the Former
ExxonMobil facility, shown on Figure 1:

Residential Use Restriction: Facility property shall not be used for any residential use, child care
facility, nursery school, preschool, playground, hotel, motel, inn, bed and breakfast, rooming house,
nursing home, rehabilitation center, hospital or community center.

Well Installation Restriction: Installation of any water wells for drinking or irrigation purposes is
prohibited.

Groundwater Use Restriction : Groundwater at the Facility property shall not be used for any purpose
other than the monitoring or remediation activities required by VADEQ and EPA.

Vapor Intrusion Restriction: A vapor intrusion control system, the design of which shall be approved
by VDEQ, shall be installed in each new structure constructed above the contaminated groundwater
plume or within 100-foot around the perimeter of the contaminated groundwater plume.

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Engineering Controls (ECs) Status:

Vacuum Track Extraction : Enhanced fluid recovery events are performed via vacuum truck extraction
annually over the course of 32 hours at monitoring wells MW-11, MW-33, MW-34 and MW-35.
During the latest 2018 event, approximately 1,065 gallons of impacted water and 14.71 pounds oftotal
petroleum hydrocarbons (TPH) vapor were recovered. The 2019 extraction event was observed by
VDEQ and EPA during the long-term stewardship site visit. Approximately 100 lbs of TPH have been
removed cumulatively over nine events.

Monitored Natural Attenuation: Currently, there are sixteen (16) active groundwater monitoring wells
sampled annually at the Facility. All wells sampled are analyzed for Volatile Organic Compounds
(VOCs) while subsets are sampled for Semi-volatile Organic Compounds (SVOCs) and total Lead.
Groundwater results are screened in comparison to EPA Maximum Contaminant Levels (MCLs) where
applicable.

During the latest sampling events in 2018, Benzene concentrations in groundwater observed at six (6)
monitoring wells exceeded the MCL of 5 ug/L, with detected concentrations ranging from 36 ug/L to
810 ug/L. MTBE concentrations in groundwater observed at three (3) monitoring wells exceeded the
EPA's Site Specific Proposed Remediation Standard of 40 ug/L, with detected concentrations ranging
from41 ug/L to 5,100 ug/L. All wells with elevated Benzene and MTBE concentrations in groundwater
are located near the southwest quadrant of the Facility adjacent to the tank truck loading rack and
oil/water seperator. The highest contaminant concentrations were observed at monitoring wells MW-
11 and MW-33, which consistent with historical data. ExxonMobil will continue to monitor Facility
groundwater on an annual basis.

Reporting Requirements/Compliance: ExxonMobil submits annual Groundwater Monitoring and
Sampling reports summarizing groundwater and VTE results. The latest report was received on
February 28, 2019. No transfer of property, change in use of the property, or work that will affect
contamination at the property has been reported. Currently, the Facility is in compliance with the
Consent Order.

Mapping: The EPA facility website map displays the entire Facility boundary of the approximate 10-
acre Former ExxonMobil Manassas Terminal. A downloadable geospatial PDF map is available on
EPA's corrective action facility webpage under the "Reports, Documents and Photographs" section,
found here.

Conclusions and Recommendations: No institutional or engineering control deficiencies were
identified. EPA has determined that the remedy institutional and engineering controls have been fully
implemented. EPA suggested minor maintenance of groundwater monitoring well pads. The remedy
remains effective in being protective of human health and the environment.

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Remedv Review and Assessment Questions:

Yes

No

Notes

• Are ICs eliminating or reducing exposure of all potential
receptors to known contamination?

X





• Do the ICs provide control for the entire extent of
contamination?

X





• Have any new wells been installed at the facility?



X



• Is the current groundwater elevation and direction
similar as mentioned in the previous studies?

X





• Groundwater contaminants (VOCs) stable or decreasing
in concentration?

X





• Are groundwater monitoring wells intact and secured?



X

Screws were missing from
monitoring well caps at
multiple locations

• Any suggested changes the number and location of
monitoring points and/or monitoring frequency?



X



• Have there been construction of new structures within
the vapor intrusion restriction zone?



X



Attachments:

Figure 1: Aerial Map of the Former ExxonMobil Facility
Picture 1: Loading Rack and Vacuum Truck

Picture 2: Vacuum Truck Extraction of Groundwater at Monitoring Well MW-34
Picture 3: Vacuum Truck Extraction of Groundwater at Monitoring Well MW-35
Picture 4: Monitoring Well MW-32
Picture 5: Monitoring Well MW-33
Picture 6: Monitoring Well MW-11

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Figure 1: Aerial Map of the Former ExxonMobil Facility

0 50100 200 300 400 500

l Feet I

Former ExxonMobil
Manassas Terminal
(Current Sunoco Terminal)
10315 Balls Ford Road
Manassas. VA 20109
EPA ID: VAD048565279 J

ENT1RE_FACILITY	At

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Picture 1: Loading Rack and Vacuum Truck

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Picture 3: Vacuum Truck Extraction of Groundwater at Monitoring Well MW-35

Picture 4: Monitoring Well MW-32

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Picture 5: Monitoring Well MW-33

Picture 6: Monitoring Well MW-11


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