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GEOTECHNICAL

ENSR International
Removal and Disposal of Petroleum Contaminated Soil

Project Background
ERRG was hired by ENSR International in September of 2004 to excavate and dispose of petroleum contaminated soil from a former service station site in Vallejo, CA. The area of the excavation was approximately 35 feet by 55 feet with a depth to 20 feet below surface grade (bsg). Although groundwater was anticipated between 7 and 20 feet, no groundwater was encountered.

During the excavation ERRG was required to segregate the impacted soil from the non-impacted soil. The original bid was based on the excavation of 1,425 cubic yards, of which 430 cubic yards was expected to be clean material suitable for backfill. The actual excavation approached 2,500 cubic yards. Approximately 2,000 yards was eventually sent off site for disposal to a licensed landfill.

The excavation process was complicated by the size of the excavation area, the proximity to adjacent buildings, on-site structures and power lines that ran across a corner of the site. In order to perform the excavation, some type of shoring was necessary. ERRG designed and implemented a sliding rail system to accommodate excavation activities. The system worked very well, and excavation activities were completed without incident.

ERRG was also responsible for the import of suitable backfill material that was not already on site, placement of the backfill, compaction of the backfill and the placement of an asphalt cap over the excavation area. Project activities were completed in December of 2004.