Project Summary for
Don Pedro Reservoir Hydrocarbon Contamination

Owner: Turlock Irrigation District

Location: Moccasin Point, California

Project Description:
This Project involves the initial emergency response, investigation, and remediation of a significant gasoline subsurface discharge which was impacting the reservoir waters. Gasoline leaked from several locations along a pipeline from gravity feed underground storage tanks connected to a floating marina. The reservoir water level was rising 1.0 feet per day. AGS excavated a large quantity of contaminated soil ahead of the advancing water level, installed numerous soil borings, and monitoring wells. Approximately 90,000 gallons of contaminated ground water was collected from surface springs and interceptor trenches, remediated and disposed. The project area was submerged below approximately 50 feet of water. Monitoring wells were extended by AGS divers to facilitate monitoring. Lake water contaminate and chemical parameter profiles, bottom sediment sampling, and remediation of excavated soils are currently in progress.

Submerged soil borings were conducted with a barge mounted drill rig. Additional ground water studies were conducted to assess the contaminant plume remaining in the fractured bedrock beneath the reservoir. AGS excavated and remediated the remaining contaminated soil when the reservoir levels drop in the fall of 1994. A Final Remediation Plan was prepared and a ground water treatment system installed. AGS is currently conducting the long term monitoring.

Estimated Completion Date: 1997

Contractor Status: Prime Contractor and Project Manager

Owner Contact: Mr. Blaine L. Cornell, Don Pedro Recreation Agency,
31 Bonds Flat Road, La Grange, California 95329, (209) 852-2396