SITE INFORMATION AND CORRESPONDENCE

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Margaret Lagorio [EH] From: Margaret Lagorio [EH] Sent: Monday, May 15,2006 3:27 PM To: Donna Heran [EH]; Laurie Cotulla [EH] Subject: Flag City Shell Apex, the consultant, for Flag City Shell had stated in their Interim Remediation Plan for the site that InStrat would perform batch extraction at the site. I called and Apex verified that InStrat was hauling away the extracted groundwater. I called Instrat and they are a Non-hazardous Waste Water Facility located in the Rio Vista city limits. They haul Non-hazardous Waste Water to their facility and treat it using granular activated carbon and Sunsolve(a synthetic material mixed with carbon specilized for MtBE and TBA). Since it is non-hazardous waste, a treatment permit from the State is not required. Their only permit is from the City of Rio Vista and they discharge the treated water to the City of Rio Vista sewer. They use the consultants lab data to show the waste is non-hazardous and take samples from their trucks periodically to compare with the consultants results. The last conversation I had with Apex staff about the extraction process was May 1, 2006. On the first day they did extraction from Extraction Well 4 and they pumped directly from the well to the truck. Apex personell took pre and post water samples from Extraction Well 4 (highest MtBE concentrations are in this well)for this first extraction activity. The second week of extraction they used Extraction Well 3 (closest to UST system)and the pre and post samples were collected from that well. It took about 6 hours to pump directly from the extraction well, so the pump rate was about 13 gallons per minute. They had to pay Instrat for the 6 hours of time so they devised another plan for the extraction process. Apex personell start the pumping of the water from the 6 inch diameter casing extraction well into the 6000 gallon poly tank and after 1/2 hour they take a water sample from the pipe entering the poly tank, then the water is automatically pumped into the tank until a high level switch on the poly tank shuts off the pump when 4800 gallons is in the poly tank. It takes about 36 hours to pump the 4800 gallons from Extraction well 4 into the poly tank, so the pump rate is less than 2.5 s in the of the pallons oly taner knute. The begins,Apexracted personell start ter pumping from poly otank for a the extraction well hen the vacuum and after 1/2 hour ruck they arriveand s a sample. It takes the vacuum truck about 20 to 30 minutes to empty the poly tank. There is a phone/computer line connected to monitoring devices of the poly tank and pumping system so the consultant is instantly notified of any problems (tank overfill, pump shut down etc.). This information is all via phone conversations. They started this process in April and the quarter ends in June so the written report won't be submitted until August. I hope all this makes sense. 1