SITE INFORMATION AND CORRESPONDENCE_CASE 2 FILE 2

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tt ,, �s CHRONOLOGY Former Shell Service Station 1071 North Main Street Manteca, California LOP Groundwater Site 08/15/96 Two 8,000-gallon and one 10,000-gallon underground storage tanks (UST), four product dispensers, and associated .piping removed from the site under permit issued by Environmental Health Department (EHD). Inspector noted tank and pipe conditions as poor. Eight soil samples were collected beneath the USTs at approximately 13 to 25 feet below ground surface (bgs), four soil samples were collected beneath the dispensers at approximately 3 feet bgs, and twelve soil samples were collected beneath the piping and vent lines at approximately 3 to 9 feet bgs. 08/21/96 EHD filed Unauthorized Release Form URF#97-U07. 06/11/97 Site entered into the Local Oversight Program (LOP). 06/16/97 Notice of Responsibility sent to Alex Perez of Shell Oil Products. EHD directed work plan for additional investigation to be submitted by July 21, 1997. 07/16/97 Report submitted to EHD presenting analytical results for UST removals. The maximum total petroleum hydrocarbons as gasoline (TPHg) concentration detected in soil samples collected beneath the USTs was 1,300 mg/kg at 13 feet bgs; beneath the dispensers was 1,200 mg/kg at 4.5 feet bgs; and beneath the piping was 3.1 mg/kg at 8 feet bgs. About 100 cubic yards of additional soil from beneath the former USTs was excavated. The soil was stockpiled on site, eventually sampled and placed back in the excavation. 09/16/97 EHD approved work plan for installation of three monitoring wells; one located adjacent to the former USTs; one located southeast of the former USTs near the dispenser island along North Main Street; and one located southwest of the former USTs at the southwest corner of the property. 12/23/97 Boring permit was issued by EHD for installation of three monitoring wells on this date. I 03/25-26/98 Three monitoring wells were installed onsite this date.