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r <br /> a <br /> Canepa's Car Wash <br /> 248 East Park Street,Stockton,California <br /> Second Quarter Groundwater Monitoring Report,April 2006 <br /> Page 2 of 5 <br /> •� Summary of April 2006 Quarterly Groundwater Monitoring Results <br /> Field Active <br /> Number of monitoring wells 7 Number of monitoring wells sampled 7 <br /> Dates monitored 4128106 <br /> Site Hydrology <br /> Average depth to groundwater below 24 14 feet Average increase(+)/decrease(—).in -2 34 feet <br /> monitoring well measuring points depth to groundwater since last (shallower) <br /> sampling <br /> The lowest(deepest) groundwater <br /> Approximate groundwater flow direction North elevation has consistently been <br /> measured at monitoringwell MW-2 <br /> Groundwater Contamination <br /> Wells containing free product None Fells with petroleum hydrocarbon 4 <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 2 <br /> benzene MCL <br /> Range in concentrations <br /> Benzene(pg/L) <0 5—6,900 <br /> BTEX Toluene(pg/L) <0 5--1,700 <br /> MTBE Ethyl Benzene(}tg/L) <0 5—2,100 <br /> Nature of contamination TPH-G Total Xylenes(gg/L) <1 0—6,400 <br /> 1,2-DCA MTBE(pg/L) <0 5—1 4 <br /> TPH-G(mg/L) <0 05—42 <br /> 1,2-DCA(pg/L) <0 5—70 <br /> • idncLs <br /> pg/L=nncrograms per Mer=parts per billion(ppb) <br /> mg/L=milligrams per liter=parts per nullion(ppm) <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 notedin the irutial groundwater field inspection samples from the wells A slight <br /> hydrocarbon odor was noted in monitoring wells MW-3 and MW-6 A moderate hydrocarbon odor was <br /> noted in monitoring well MW-5 A strong hydrocarbon odor was noted in monitoring well MW-2 <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 momtoring field forms and groundwater measurement field form <br /> are included in 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 April 2006 <br /> momtoruig event was 2 34 feet higher than measured in January 2006 The groundwater elevation <br /> contours for the current monitoring event indicate a groundwater gradient variable across the Site, but <br /> generally toward the north <br /> 4M <br /> �� CONDOR <br />