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CLEARWATER <br /> . G R O U P, I N C <br /> Environmental Services <br /> �a <br /> QUARTERLY GROUNDWATER MONITORING REPORT , <br /> FIRST QUARTER 2001 , <br /> E-Z Serve#100878 <br /> 1012 W Yosemite, Manteca, California <br /> March 29,2001 <br /> BACKGROUND <br /> Project activities were initiated in late 1989 following the detection of a suspected fuel hydrocarbon <br /> release,which was observed during the tank removal work in December,1989 As a result of this three <br /> monitoring wells were installed by Associated Soils Analysis (ASA) in 1991 Results of well <br /> installation and sampling confirmed the presence of low to moderate concentrations of fuel hydrocarbon <br /> constituents in groundwater in the vicinity of the former USTs <br /> Additional project activities include the installation of eight (8) monitoring wells and quarterly <br /> groundwater monitoring The results of the sampling events over the past several years have <br /> demonstrated a steady decline in contaminant concentrations Based on this trend, Clearwater proposed <br /> site closure in February 1999 Closure could not be granted by the County without approval from the <br /> Regional Water Quality Control Board (RWQCB) The RWQCB recently reviewed the file and <br /> discussed the results with the County and determined that additional rounds demonstrating <br /> contaminant reduction would be necessary before considering the case for closure <br /> I <br /> GROUNDWATER MONITORING FIELD ACTIVITIES <br /> Date'of field activities February 5,2001 <br /> Wells gauged MW-1 through MW-8 <br /> Wells sampled MW-1 through MW-8 <br /> Groundwater analyses Total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, <br /> ethylbenzene & xylenes (BTEX), and fuel oxygenates methyl tert-butyl <br /> ether (MTBE), tert-Butanol, Diisopropyl ether, Ethyl-tert-butyl-ether <br /> & tert-Amylmethyl ether (all by EPA Method 82605) <br /> Laboratory Kiff Analytical, Davis, CA <br /> Remarks <br /> During the sampling event green liquid was noted in and around the well cap of MW-3 Car <br /> maintenance work was being conducted'on top of the well box and it was confirmed by the station <br /> operator that the green liquid was antifreeze (ethylene,glycol) from recent repair work ' <br /> • II r i , <br /> I <br /> I � � ' <br /> 1520 Third Street,Slilte 104 O Oakland,Cahforma,94607 e (Telephone 510-893-5160 o Fax 510-893-5947 <br /> I <br /> I �r <br />' E ' I <br />