RI & FS - Gasoline Service Station

Campbell Environmental Group staff were contracted by the Maine DEP to investigate and remediate a site impacted by gasoline.  The purpose of this work was to remediate petroleum impacted soil that threatened the water quality of a nearby brook and private water supply wells.  The project was completed in three phases: 

  • completed a subsurface investigation to determine the extent and magnitude of petroleum impact to the soil and groundwater;
  • designed and installed a petroleum recovery system along a brook and a soil vapor extraction system at the service station to recover petroleum; and 
  • completed of a feasibility study and executed the selected remedial approach, soil removal, to remediate the zones of soil not captured by the soil vapor extraction system.

Excavation of petroleum impacted soil

The first phase of work, which included the completion of a subsurface investigation, revealed petroleum impact to the subsurface soils and groundwater across the site as well as to a nearby brook.  The results of the investigation led to the second phase of work which included the installation of an interceptor trench and passive petroleum recovery system on the bank of the brook.  This system was designed to recover gasoline seeping from the base of an embankment and prevent migration of gasoline into the brook.  Gasoline recovery included initial recovery using sorbents and upgrading the system to an ORS Environmental Equipment Filter Bucket and two ORS Filter Scavengers.  Over 1,400 gallons of gasoline were recovered during five months of operation. 

CEG personnel also assisted in the design and supervised the installation of an in-situ soil vapor extraction system on the service station property to remove volatile organic compounds from the unsaturated soil.  The soil vapor extraction system operated continuously from July 1994 to June 2003.  During this time, approximately 16,400 gallons of gasoline were recovered from the subsurface. 

CEG staff assisted in the design and completion of a dual-phase vapor extraction test at the site. The test included the installation of one air sparge point. The results of the pilot test showed that the dual phase technology may have been successful at the site, but the formation did not allow for the effective use of air sparge technology.

The third phase of work included the completion of a feasibility study to evaluate remedial alternatives for the groundwater and deeper zones of contamination in the soil.

Cross section of the site

Soil excavation and landfarming were the selected remediation and in June 2003, the soil vapor extraction system was decommissioned and CEG was contracted by the Maine DEP to supervise the excavation of the petroleum-impacted soil for landfarming. A total of 4,500 cubic yards of petroleum-impacted soil, was removed and transported to a Maine DEP approved landfarm site.   The soil was mixed with compost and spread to a maximum thickness of 5 inches, in accordance to Maine DEP's landfarm guidelines.  The landfarm soil was rototilled, monitored for volatile organic compounds, and sampled for gasoline range organics according to a Maine DEP approved schedule.  Within 6-months of landfarming the soil, the soil was below the Maine DEP cleanup goal of 25 mg/kg for gasoline range organics in soil. 

Based on these results and ongoing aeration of the landfarmed soil, CEG recommended site closure of the site, which was approved by the Maine DEP.

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Campbell Environmental Group

173 Gray Road

Falmouth, ME 04105

(207) 253-1990 f(207) 253-1988