ARCHIVED REPORTS_XR0006702 - Laserfiche WebLink

Home Browse Search

Canepa's Car Wash 6230 Pacific Avenue,Stockton,CA Fourth Quarter Groundwater Monitoring Report,October 2005 Page 2 o£9 Table I —Summa of October 2005 !2uarteE!y Groundwater Monitorin 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 10/13/2005 wells measured for water level Site Hydrology Average depth to groundwater below 39 12 feet Average increase (+)/decrease(—) in -+-0 32 foot shallow monitonng well measuring depths to groundwater since last (deeper) points (excluding MW-1 and-11) sampling Approximate flow direction and Elliptical cone of depression with foci at MW-1 and MW-11 ' groundwater gradient Groundwater Contamination Monitoring wells containing free None Monitoring wells with petroleum I product(not including SV-4) hydrocarbon odor noted(not including SV-4 Number of monitoring wells with 3 Number of monitoring wells with 4 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(µg/L) <0 5-- 11,800 Additives, Toluene(µg/L) <0 5-- 1,180 TPH-G Ethyl Benzene(gg/L) <0 5— 1,560 Total Xylenes (µg/L) <1 0—3,206 MTBE(µg/L) <0 5—9,890 1,2-DCA(4g/L) <0 5—54 5 EDB (4g/L) <05— 48 TPH-G (m/L <0 05—38 2 Note Pumping wells MW-1 and MW-I 1 were active FIELD OBSERVATIONS iOn October 13, 2005, 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, clanty, 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, however, sheen was observed in the field inspection sample collected from SV-4 A strong petroleum hydrocarbon odor was noted in monitoring well MW-2 and soil vapor extraction well SV-4 iGROUNDWATER 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 October 13, 2005 indicate a groundwater gradient generally toward the northwest (consistent with histonc gradients) but with a localized gradient toward MW-1 and MW-11 (cone of depression) MW-1 is currently used as the primary groundwater 1 1 ' �� CONDOR