Lessard Environmental Incorporated: Case Study #3

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Remedial Case Study

Overview:

Approximately 2,000 gallons of heating oil was released from a split at the end of a new 5,000 gallon underground storage tank (UST). About 300 gallons of fuel oil was recaptured via a vacuum truck and 500 cubic yards of soil was promptly excavated and disposed of at a soil batching facility. Remediation of the unaccounted for heating oil was exacerbated due to the infiltration of the heating oil into a French drain system surrounding the perimeter of the home. Remedial solutions at this property included soil removal, product & groundwater recovery, and chemical oxidation (Chemox). The state's most stringent groundwater standards (GW-1) had to be met due to the site's proximity to a private drinking water supply well.

Assessment:

Assessment and remedial activities were conducted as an Immediate Response Action (IRA). The following assessment activities were performed to delineate the contaminant plume, design an appropriate remedial solution and monitor the effectiveness of the solution.

Collected post excavation soil samples
Conducted a total of 8 soil borings that were completed as groundwater monitoring wells and an additional 2 groundwater monitoring wells set into bedrock
Detected heating oil Non Aqueous Phase Liquid (NAPL) ranging up to 2 feet in thickness
Collected, field screened, and lab analyzed select soil and groundwater samples
Surveyed monitoring wells and developed a groundwater flow model
Assessed sub-slab soils beneath basement floor
Prepared various reports including a Phase I Site Investigation, Tier Classification, IRA Plan, IRA Status

Response Activities:

A variety of response activities were performed to address the soil and groundwater affected under, adjacent to and down gradient of the residence:

Excavated and manifested the disposal of approximately 550 cubic yards of soil on 2 separate occasions
Installed a product recovery trench and (3) 6″ recovery wells
Recovered approximately 5,000 gallons of groundwater mixed with fuel oil on 6 separate occasions from excavations, monitoring wells and the product recovery trench
Flushed perimeter French drain with a non-toxic, biodegradable, surfactant cleaning solution to recover residual fuel oil remaining in the drain and surrounding pea stone
Designed and installed a series of 6 PVC Chemox injection points
Performed 6 Chemox injection events — 3 in July and August 2000 and 3 in August 2001
Conducted post injection groundwater sampling to confirm remedial results

Key Monitoring Results:

Current Site Status:

IRA Completion Statement filed
Quarterly sampling through July 2003
Response Action Outcome (RAO) expected in August 2003