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Caroepa's Car Wash 248 East Park Strcet,Stockton,California Fourth Quarter Groundwater Momtonng Report,October 2004 Page 2 of 5 Summary of October 2004 Quarterly Groundwater Monitoring Results Field Activit Number of monitoring wells 7 Number of monitoring wells sampled 7 Date(s) monitored 10/12/04 Site Hydrology Average depth to groundwater below Average increase(+)/decrease(—)in monitoring well measuring points 29 08 feet depths to groundwater since last +1 17 foot sampling The lowest(deepest)groundwater Approximate groundwater flow direction North elevation has consistently been measured at monitoring well MW-2 Groundwater Contamination Wells containing free product* None Wells with petroleum hydrocarbon 3 odor noted Number of wells with benzene Number of wells with benzene concentrations below the benzene MCL 5 concentrations at or above the benzene 2 MCL Range in concentrations Benzene(µg/L) <0 5—7,600 BTEX Toluene(pg/L) <0 5—950 Nature of contamination MTBE Ethyl Benzene(µg/L) <0 5— 1,400 TPH-G Total Xylenes(pg/L) <1 0—3,700 MTBE(ug/L) <0 5—5 1 TPH-G(mg/L) <0 05—25 *Note A sheen was noted in the purge water from MW-2 and MW-5 FIELD OBSERVATIONS All monitoring wells were purged using a clean, single-use, polypropylene, disposable bailer Approximately three well casing volumes of water were purged from each well No sheen or separate phase petroleum was noted in the initial groundwater field inspection samples from the wells, however, a slight sheen was noted in the purge water bucket after purging MW-2 and MW-5 A moderate hydrocarbon odor was noted in the groundwater inspection sample from well MW-3, and a strong hydrocarbon odor was noted in the groundwater inspection samples from wells MW-2 and MW-5 No odor was noted in the initial groundwater field inspection sample from MW-6, however, a strong hydrocarbon odor was noted subsequent to purging GROUNDWATER ELEVATIONS AND GRADIENT The static water level in each well was measured to the nearest 0 01 foot with a battery-operated, flat tape, water level indicator The groundwater monitoring field forms and groundwater measurement field form are included in Attachment C The groundwater table has been above the top of all well screens since the August 1996 monitoring event The average groundwater elevation measured during the October 2004 monitoring event was 1 17 feet lower than measured in July 2004 The groundwater elevation contours for the current monitoring event indicate a groundwater gradient variable across the site, but generally toward the north �� CONDOR