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CLEARA ER <br /> G R O ',U P, I N C. <br /> • Enoiranmrn[af Srraires <br /> QUARTERLY GROUNDWATER MONITORING REPORT <br /> k THIRD QUARTER 1996 <br /> Boettcher Western Properties <br /> 4555 North Pershing Avenue, Stockton, California <br /> r <br /> October 16,194 <br /> ,BACKGROUND q <br /> The site is currently unoccupied and.is.used primarily as a two-lane access road leading to an adjacent <br /> shopping center. The si#e.was foruieriy p�iated as a card lock refuelingstation. Nine soil borings were <br /> drilled in June 1991;..�soil°'samplea..;opl1e&ed.from the-brb ngs indicated the presence of "gasoline <br /> contamination at a depth of approximately 25 feet bgs. Three underground fuel storage tanks (USTs) <br /> containing leaded gasoline, unleaded gasoline, end diesel fuel were excavated and removed from the <br /> site by TreaTek, Inc.,on January 8, 1992. In November 1992,McLaren/Hart installed five groundwater <br /> monitoring wells (MW-1 through MW-5) to a makimum depth of 40 feet bgs. Clearwater began <br /> quarterly groundwater ixf6hiforing and sampling at the sitein December 1994. <br /> GROUNDWATER MONMORING,ACTIVITIES I I <br /> Date of field activities:`- sptenter..7S;1996 <br /> Weds monitored/sampled:' MW-. 111.1 Wi 1, MW-3, MW-4, and MW-5 <br /> Analytes tested: 1:L i- P�Ig,BTEX,and MTBE <br /> Analytical methods: EPA Methods 8015/8020 (Irnodified) <br /> - Laboratory: ;. .American Environmental Network, Inc., Pleasant Hill, CA <br /> GROUNDWATER MONITORING TRESTS <br /> Depth to water: 21.79 to 22.35 feet below grade <br /> Flow direction/gradient: Northeast at 0.43% <br /> TPHg concentration range: <50 ppb in all wells �I <br /> Benzene concentration range: 0.7 ppb (MW-2) to 1.9 ppb`(MW-3); <0.5 ppb in other wells <br /> MTBE concentration range: <5.0 ppb in all wells <br /> Remarks: The direction of groundwater flow is generally consistent with previous measurements; <br /> groundwater analyses indicate that hydrocarbon concentrations may be attenuating. <br /> PROJECT STATUS <br /> Quarterly groundwater monitoring will be continued <br /> ATTACHMENTS <br /> I <br /> 9 ' <br /> • Site Location Map (Figure 1) <br /> • Site Plan (Figure 2) <br /> • Groundwater Elevation Contour Map-9/25/96(Figure3) <br /> • Hydrocarbon Distribution Map-9/25/96(Figure 4) <br /> I <br /> • Groundwater Elevations and Analytical Results (Table 1) <br /> • Clearwater Gauge/Purge Calculations and Well Purging Data (Appendix A) ; <br /> • Laboratory Reports and Chain-of-Custody Form (Appendix B) <br /> • Clearwater Groundwater Monitoring and Sampling Protocols (Appendix C) <br /> i <br /> I <br /> I <br /> i <br />