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r . <br /> 5 <br /> Working to Restore Nature <br /> Quik Stop Market No. 132 <br /> Project No. F7132.93 June 8, 1993 <br /> analyses-of aoil-saiholes`'indiycated_that petroleum fiydrocarbon;contaminated soil above tbe� <br /> i+ water table—in„-the vicinity�-of�-the�-storage--tank excavation�hadw been=removed:r All <br /> �., t <br /> contaminated' soil” was remdved""from J_the station`-and-,properly--disposed—(Exceltech, <br /> November 1990)_ 1Vew_double-walled:fibergl ss_,USTs�were installedat_the sit_ a and he <br /> remaining_excavation-was-backfilled_with_clean_fill, The canopy; pumps, and Concrete I <br /> surface'werereplacedand. kin in'operation_in°March 49 <br /> 1+ Well MW-1 was destroyed on October 3, 1990, due to concerns that it may have connected <br /> two water bearing units. On April 2, 1991, RESNA replaced the destroyed groundwater <br /> monitoring well, MW-1, with two monitoring wells, designated MW-1R and MW-5. MW-1R <br /> was designed to monitor the lower aquifer and MW-5 to monitor the upper aquifer <br /> discovered during the installation of MW-1. Analyses of all subsurface and analytical data <br /> indicated the presence of two aquifers beneath the eastern portion of site. It was found that <br /> the lower aquifer had no detectable TPHG or BTEX and the upper aquifer contained <br /> TPHG and some BTEX components (Exceltech/RESNA, July 1991). <br /> At the time of the initial groundwater sampling for MW-1R and MW-5, the San Joaquin <br /> County Public Health Services (SJCPHS) required that groundwater samples be collected <br /> from all monitoring wells and analyzed for fecal coliform. On April 8, 1991, sampling for <br /> this analysis was performed and fecal coliform was only detected in the sample collected <br /> from MW-2. It was the decision of SJCPHS that the groundwater samples from this well <br /> shall continue to be analyzed for fecal coliform. In subsequent sampling, no fecal coliform <br /> has been detected in this well. It is known that a main sewer line was located beneath West <br /> Hammer Lane, approximately 30 to 40 feet away from MW-2. Since this is the only well <br /> in which any fecal coliform has been detected and it is the well closest to this sewer line, <br /> it is likely that this sewer line was the source of the fecal coliform. Such conditions are <br /> beyond the control of Quik Stop Markets. The purpose of these monitoring wells is to aid <br /> in the determination of the presence and/or extent of petroleum hydrocarbons in the <br /> groundwater. It was the recommendation of RESNA that Quik Stop Markets be permitted <br /> to discontinue fecal coliform testing of the groundwater collected from monitoring well <br /> ' MW-2. In a letter to Quik Stop Markets dated December 5, 1991, the SJCPHS reduced the <br /> required fecal coliform sampling frequency in monitoring well MW-2 to semi-annual (every <br /> other quarter). Since the initial occurrence of fecal coliform in April 1991 no fecal coliform <br /> has been detected in this well. <br /> Information obtained as of August 1991 indicated that the gasoline plume extends beyond <br /> the station boundary to the east. In an effort to determine the extent of this. possible <br /> contamination RESNA and Quik Stop Markets requested permission to enter the property <br /> to the east. These requests were not successful. This site is occupied by a Taco Bell <br /> restaurant. In August 1991, RESNA initiated quarterly pumping of monitoring well MW-5. <br /> ,, A-2 <br />