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Report—Vapor Extraction/Air Sparge Remedial System Page 2 <br /> Former Manna Pro Site <br />' Project No 207 3 <br /> September 26, 2003 <br /> days Based on the results of the operation, the plans for the final remedial system were <br /> modified in an addendum to the CAP Between June and September of this year, the final <br />' remedial system was constructed and placed in operation as documented below <br /> 1.1 Site History <br />' The former Manna Pro facility was originally constructed in 1956 as a grain mill, which <br /> processed animal feed products Two 10,000-gallon underground diesel tanks and two <br /> 5,000-gallon underground gasoline tanks and a single 10,000-gallon underground <br />' gasoline tank were formerly in use at the site These tanks were used to fuel vehicles <br /> operated at the facility, and were located just northeast of the main entrance to the <br /> Property from El Dorado Street <br /> In January 1990, as part of an environmental site assessment, Manna Pro's consultant at <br /> that time, WHF, installed six soil borings near the tanks detected gasoline and diesel <br /> hydrocarbons in soil samples In July of 1990, Semco, a tank removal contractor, <br /> removed the tanks and petroleum hydrocarbons were detected in soil samples from <br /> beneath 4 of the 5 tanks Based on the results of this initial soil sample analysis, several <br />' hundred yards of fuel-impacted soil were excavated The excavation reached a total <br /> depth of about 15 feet <br /> rIn October of 1990, ERM West conducted additional work to characterize the lateral and <br /> vertical extent of the hydrocarbon contamination in the sub-surface This included <br />' installing 25 soil borings into groundwater of which, a total of 6 borings were later <br /> converted to groundwater monitoring wells Between 1993 and 1996, Groundwater <br /> Technology Inc (GTI) installed four additional monitoring wells, a combination <br />' groundwater/vapor extraction well and three observation wells These observation wells <br /> were used for the completion of groundwater pumping and vapor extraction pilot tests In <br /> 1996, GTI conducted a feasibility study, which included pilot level field work to test <br />' several remedial options The GTI report concluded that a combination of vapor <br /> extraction and groundwater pumping offered the most attractive option for remediation of <br /> the gasoline plume at this site <br /> Up to April of 2000, a total of eleven groundwater monitoring wells, three observation <br /> wells, and one combination groundwater and vapor extraction well were constructed on <br />' or near the site In April of 2000, concurrently with field work associated with a pilot <br /> remedial test, Geo-Phase Environmental drilled and constructed a 97-foot deep <br />' monitoring well intended to investigate the vertical distribution of gasoline hydrocarbons <br /> Simultaneously, a 55 foot air sparge well, a 50 foot vapor extraction well, a 50 foot <br /> boring backfilled with Oxygen Release Compound and two 30 foot air monitoring wells <br />' were also installed as part of the pilot test A 5-day test of vapor extraction and air <br /> • sparging was instituted and concluded that the method was a feasible means of adequately <br /> 2937 Veneman Ave,#}11240 Geo-Phase Environmental Inc Phone(209)569-0293 <br /> Modesto, CA 95356 Fax(209)569-0295 <br /> I <br />