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Canepa's Car Wash <br /> 248 East Park Street,Stockton,California <br /> Thud Quarter Groundwater Monitoring Report,July 2005 <br /> Page 2 of 5 <br /> • Summary of July 2005 Quarterly Groundwater Monitoring Results <br /> Field Activity <br /> Number of monitoring wells 7 Number of monitoring wells sampled 7 <br /> Dates monitored 7115105 <br /> Site Hydrology <br /> Average depth to groundwater below Average increase(+)/decrease(—) in <br /> monitoring well measuring points 26 47 feet depth to groundwater since last -0 63 feet <br /> sampling <br /> The lowest(deepest)groundwater <br /> Approximate groundwater flow direction North elevation has consistently been <br /> measured at monitorin well MW-2 <br /> Groundwater Contamination <br /> Wells containing free product None Wells with petroleum hydrocarbon 2 <br /> odor noted <br /> Number of wells with benzene Number of wells with benzene <br /> concentrations below the benzene MCL 5 concentrations at or above the benzene 2 <br /> MCL <br /> Range in concentrations <br /> Benzene(pg/L) <0 5— 11,000 <br /> BTEX Toluene(tig/L) <0 5—5,000 <br /> Nature of contamination MTBE Ethyl Benzene(µg/L) <0 5—2,600 <br /> rPH-G Total Xylenes(µg/L) <1 0—8,600 <br /> MTBE(pg/L) <5 0-3 0 <br /> TPH-G(mg/L) <0 05—76 <br /> • FIELD OBSERVATIONS <br /> All monitoring wells were purged using a clean, single-use, polypropylene, disposable bailer <br /> Approximately three well casing volumes of water were purged from each well No sheen or separate <br /> phase petroleum was noted in the initial groundwater field inspection samples from the wells A moderate <br /> hydrocarbon odor was noted in monitoring wells MW-2 and MW-5, and a slight sulfurous odor was noted <br /> in MW-3 <br /> GROUNDWATER ELEVATIONS AND GRADIENT <br /> The static water level in each well was measured to the nearest 0 01 foot with a battery-operated, flat tape, <br /> water level indicator The groundwater monitoring field forms and groundwater measurement field form <br /> are included to Attachment C The groundwater table has been above the top of all well screens since the <br /> August 1996 monitoring event The average groundwater elevation measured during the July 2005 <br /> monitoring event was 0 63 foot higher than measured in April 2005 The groundwater elevation contours <br /> for the current monitonng event indicate a groundwater gradient variable across the Site, but generally <br /> toward the north <br /> CO IV f]O R <br />