A sudden release of 200 gallons of #2 fuel oil to a dirt floor basement occurred due to the failure of the legs for one of two above ground storage tanks (ASTs). The release occurred immediately following a routine delivery. The #2 fuel oil was released and flowed onto the dirt floor around the ASTs before being absorbed into the soil. There was no recovery of product. Assessment indicated that oil-saturated soils were present to a depth exceeding 16 inches and groundwater was present at approximately 24 inches below the basement floor. Impacted soil was later excavated to a depth of approximately 32 to 46 inches below basement surface and exterior of the foundation removing the #2 fuel oil from the environment. The #2 fuel oil did not migrate to surface water, or storm water catch basins, due to the hydraulic controls placed on the site and the excavation of impacted soil.
During soil excavation, select soil samples were submitted for laboratory analysis to evaluate the effectiveness of the removal action. Results indicated impacted soils remained under the foundation and excavation would require an underpin design by a structural engineer. Additional soil excavation would need to be completed from the exterior of the structure. Clean overburden soil was removed from the exterior of the foundation to an approximate depth of 4 feet below ground surface and above the bottom of the foundation. Vacuum excavation was then used to remove the impacted soil. Soil was placed in a dewatering roll-off can staged on site using a cyclone attached to the vacuum excavator. Select soil samples were submitted for laboratory analyses. Concrete underpins were installed under the foundation in place of the removed soil.
As part of the assessment activities a direct push drill rig was mobilized to the site to advance soil borings to determine the extent of the impact and the migration of the spill. Groundwater monitoring wells were installed in three of the soil borings. Groundwater samples from the monitoring wells as well as a sample from the dewatering sump were submitted for laboratory analysis. Air samples were collected from the basement, first floor and exterior of the residence to evaluate indoor air quality. Summa canisters fitted with 24-hour regulators were used to collect the air samples and were submitted for laboratory analysis. Results indicated air impact levels were within acceptable parameters.
At the completion of remedial activities all areas of remediation were restored to pre-spill conditions. REI prepared the necessary reporting to the MassDEP and a permanent Solution was achieved. All site work was completed under the direction of the REI licensed LSP.