Lessard Environmental Incorporated: Case Study #4

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Remedial Case Study

Overview:

Dissolved phase and free phase gasoline was identified at this high volume retail gasoline station and convenience store site in the late 1980's. A previous consultant designed and installed a groundwater pump and treat system to address petroleum constituents in the groundwater. This system was installed in 1991 and operated for 7 years. Site conditions improved but not to the level of State standards. LEI took over the site in 1999, reviewed site history and closed the site out via a modified risk assessment in conjunction with an AUL (Activity and Use Limitation).

Assessment:

Additional assessment activities were performed to confirm the ability to utilize a modified risk assessment in order to close out the site. The assessment activities also provided the additional data needed to perform the modified risk assessment.

Reviewed recent site history
Advanced 7 soil borings to provide additional data on soil conditions

Response Activities:

LEI discussed alternatives with the site owner and developed a strategy that met his goals. Passive response activities included the following:

Conducted a Method 2 Risk Assessment yielding site specific groundwater standards
Compared site specific standards to actual groundwater quality indicating that groundwater did not require any further remedial actions
Utilized an averaging methodology to determine if site met soil standards
Soil standards were exceeded requiring further remediation or an AUL
Prepared an AUL for the site indicating that No Further Remedial Actions are required as long as the site remains a retail gasoline station or similar commercial use
Completed a RAO (Response Action Outcome) report and an AUL

Current Site Status:

Site Closed — No Further Remedial Actions required