Storage Tanks, Spill Prevention – Construction and Remediation, Round Hill Texaco / Harper’s BP (Round Hill, Virginia)
SCS Engineers was retained to investigate and remediate petroleum contaminated soils and groundwater impacted by multiple leaking underground storage tanks (USTs) at two former gas stations. Both facilities formerly functioned as retail service stations, dispensing gasoline and diesel fuel. The properties currently operate as automobile maintenance shops.
SCS’s services included:
Excavation, transportation, and disposal of approximately 1,400 cubic yards of petroleum-impacted soils from both sites; removal and destruction of 10 USTs, and closing 4 additional USTs in-situ. The water table was not encountered.
Construction monitoring, including sampling the limits of excavation; vapor-phase headspace readings in the field; detailed measurements, sketches, and note taking; and report preparation. Thirty-three confirmatory soil samples were collected and analyzed.
Backfilling and grading the excavations with imported clean material. A geosynthetic filter fabric liner was placed between the stone and rock dust. The disturbed areas were compacted and repaved.
Frequent correspondence with the regulatory agency (Virginia Department of Environmental Quality) including the pre-authorization process for approval of activities, report submissions, verification of work performed, and reimbursement applications.
Preparation of site-specific Health and Safety Plans. Assessment of existing and potential risks to human health and environmental receptors through identified migration pathways.
Installation of 24 groundwater monitoring wells, 6 nested wells (shallow and deep), 28 extraction points, 6 injection wells, and 2 infiltration galleries. A subset of these wells is sampled on a periodic basis, and a comprehensive database of historical analytical data is maintained.
Design, acquisition and installation of two remediation systems. Each extraction system involves stinger pipes, header line, liquid ring pump, phase separator, oil/water separator, air stripper, transfer pumps, equalization tank and carbon vessels. The injection systems feature dissolved oxygen – in-situ treatment technology utilizing proprietary enzymes, microbes, biosurfactants, and nutrients. Operation and maintenance activities continue.
Design, acquisition, and installation of equipment to perform a 48-hour aquifer pumping test. A step drawdown test was conducted to determine a sustainable pumping rate. Baseline and recovery water levels were also measured on an hourly basis prior to and upon the completion of the pumping phase.