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2 .14 Sentember 2000 Interim. Remediation System Tnsta1l to ion <br /> In September 2000, ASE installed two new groundwater extraction <br /> (recovery) wells at the site and converted three piezometers into recovery <br /> wells A "pump and treat" interim groundwater remediation system was <br /> installed and began operation on September 29, 2000 <br /> 2-15 Sei2tember 2000 Alternative Water S,QLrctfo� Impacted Pronertiec <br /> In September 2000, each domestic well impacted by MTBE or 1,2-DCA was <br /> disconnected from the home plumbing The home plumbing was then <br /> connected to water tanks, which are regularly filled with water from t h e <br /> City of Manteca This temporary solution will remain in place until a <br /> more permanent solution can be implemented <br /> 2. 16 Sentember 2000 CPT 1)rilling_ aiid Monitoring Well Installation <br /> In September 2000, ASE drilled two additional soil borings using a CPT a n d <br /> installed five additional groundwater monitoring wells Groundwater i n <br /> the shallow zone (less than 19-feet bgs) flowed primarily to the north <br /> beneath the site at a gradient of approximately 0 001 -feet/foot <br /> Groundwater in the 55 to 70-feet bgs. zone flowed primarily to the <br /> south/southeast at a gradient of 0 003-feet/foot Groundwater in the <br /> deeper zone (below 100-feet bgs) flowed to the southeast at a gradient of <br /> 0 0018-feet/foot <br /> In general, groundwater samples collected from monitoring wells on t h e <br /> northern portion of the site, north of the USTs and pump dispensers, <br /> contained the highest hydrocarbon concentrations Monitoring well <br /> MW-5 contained 0 01-feet of free-floating hydrocarbons Groundwater <br /> samples collected from recovery wells RW-1 through RW-5 contained up <br /> to 140,000 ppb TPH-G, 840 ppb benzene, 18,000 ppb toluene, 4,500 p p b <br /> ethyl benzene, 25,000 ppb total xylenes, 8,100 ppb MTBE, 21 ppb TAME, <br /> 1,100 ppb TBA, and 380 ppb ethanol <br /> Groundwater samples collected from all off-site, downgradient monitoring <br /> wells screened in the water-bearing zone less than 19-feet bgs contained <br /> MTBE concentrations exceeding the DHS MCL for drinking water The <br /> highest hydrocarbon concentrations were in the groundwater sample <br /> collected from monitoring well MW-13 which contained 2,000 ppb MTBE, <br /> 1,000 ppb benzene, 8 0 ppb toluene, 1,100 ppb ethyl benzene, 1,300 ppb <br /> total xylenes, 8 6 ppb TAME, and 600 ppb TBA Groundwater samples <br /> Frank's One Stop Workplan — December 2000 <br /> -7- <br />