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Iv Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA East Quarter Groundwater Monitoring Report,January 2006 _ Page 2 of 9 • Table 1 —Summa of Janua 2006 Quarterly Groundwater Momtonna Results Field Activity Number of groundwater monitoring 11 Number of wells sampled 7 wells (not including soil vapor extraction well SV-4 Number of groundwater monitoring 11 Date(s)monitored and sampled 1/27/2006 wells measured for water level Site Hydrology Average depth to groundwater below 37 24 feet Average increase(+)/decrease()in —2 21 foot shallow monitoring well measuring depths to groundwater since last (shallower) points(excluding MW-1 and-11) sampling Approximate flow direction and Cone of depression centered at MW-1 groundwater ELdient Groundwater Contamination Monitoring wells containing free None Monitoring wells with petroleum 3 product(not including SV-4) hydrocarbon odor noted(not including SV-4 Number of monitoring wells with 3 Number of monitoring wells with 4 I concentrations below both the concentrations at or above either or benzene and MTBE MCLs both the benzene and MTBE MCLS Nature of contamination BTEX, Range of analyte concentrations Gasoline detected in the monitoring wells Oxygenates/ Benzene(gg/L) <0 5— 11,400 Additives, Toluene(µg/L) <0 5—4,540 TPH-G Ethyl Benzene(gg/L) <0 5— 1,790 Total Xylenes(gg/L) <1 0—4,403 MTBE(gg/L) <0 5—6,650 1,2-DCA(gg/L) <0 5—28 3 EDB (gg/L) <05— 34 I TPH-G m /I <0 05—36 3 Note Pumping well MW-1 was active I FIELD OBSERVATIONS On January 27, 2006, Condor representatives made field observations and collected depth to groundwater measurements at the 11 Site monitoring wells (MW-1 through MW-7, and MW-9 through MW-12D) and at one soil vapor extraction well (SV-4) MW-1 and MW-11 are used for groundwater extraction related to the operation of the groundwater treatment system Field observations included appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples), collection of water quality field parameters, and any other conditions of note Depth to groundwater measurement data is provided in Table 2, on the following page, field observations are included in the field forms (Attachment E) No sheen or separate phase petroleum was noted in bailed field inspection samples from any of the Site monitoring wells A strong petroleum hydrocarbon odor was noted in monitoring well MW-2 A moderate petroleum hydrocarbon odor was noted in monitoring well MW-11 A slight petroleum hydrocarbon odor was noted in momtonng well MW-1 and soil vapor extraction well SV-4 GROUNDWATER ELEVATIONS AND GRADIENT Groundwater elevation contours estimated for the shallow monitoring wells (MW-1, MW-2, MW-3 MW- -4, MW-5, MW-6, MW-7, MW-9, MW-10,-and MW-11) on January 27, 2006-indicate a groundwater gradient generally toward the northwest (consistent with historic gradients) but with a localized gradient I �) toward MW-I (cone of depression) MW-1 is currently used as the primary groundwater extraction well 1 f.1a CONDOR