ARCHIVED REPORTS_XR0006731 - Laserfiche WebLink

Home Browse Search

y First Quarter,2003 Quarterly Groundwater Momtonng Report Canepa s Car Wash Pacific Avenue,Stockton,CA Page 2 Table 1 . Summary of January 2003 Quarterly Groundwater Monitoring Results Field Activit Number of groundwater wells 12 Number of groundwater wells sampled 12 Number of groundwater wells 12 Date(s)monitored and sampled 1/14-15/03 monitored Site Ilydrology Average depth to groundwater below 39 45 feet Average increase(+)/decrease H in +2 19 feet monitoring well measuring points depths to groundwater since last sampling (Deeper) Approximate flow direction and 0 0053 ft/ft Northeast as measured between wells groundwater gradient MW-5 and MW-6 Groundwater Contamination Monitor wells containing free product None Monitor wells with detected odors 5 Number of monitor wells with 7 Number of monitor wells with 5 concentrations below both the benzene concentrations at or above either or both and MTBE MCLs the benzene and MTBE MCLs Nature of contamination BTEX, Range of analyte concentrations detected TPH-G, in the monitor wells MTBE Benzene(4g/L) <0 5— 15,000 Gasoline Toluene(gg/L) <0 5—980 Oxygenates Ethyl Benzene(µg/L) <0 5—2,400 /Additives Total Xylenes(gg/L) <1 0-4,100 TPH-G(mg/L) <0 05—69 M IBE(4g/L) <0 5—350 1,2-DCA(4g/L) <0 5—190 TBA( L) <5 0— 15 FIELD OBSERVATIONS On January 14 and 15, 2003, Condor representatives made field observations at the 12 site monitor wells (MW-1 through MW-11 and MW-12D), and at one soil vapor extraction (SVE) well (SV-4) Field observations included water level measurement (Table 2, on the following page), appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples), and collection of water quality field parameters Field observations are included in the field forms, Attachment D No sheen or separate phase petroleum was noted in the wells, however, a sheen was present in the purge water from MW-1 and SV-4, and a very slight broken sheen was present in the purge water from MW-3 and MW-12D A slightly sweet indistinct odor was noted in monitor well MW-11, a moderate sulfurous odor was detected in monitor well MW-3, and a strong petroleum odor was detected in monitor well MW- 1 and MW-2 GROUNDWATER ELEVATIONS AND GRADIENT Groundwater elevation contours estimated for the shallow monitor wells (MW-1 through MW-11) on January 14, 2003, indicate that the groundwater gradient is to the northeast and is generally consistent with previously estimated groundwater gradients (Figure 2, attached) Monitor well MW-12D was not used in groundwater elevation contouring due to the well's deep screen interval An estimated groundwater gradient of 0 0053 #t/ft towards the northeast was measured using water level data from monitor wells MW-5 and MW-6 The average depth to groundwater measured in the 12 monitor wells at _ the site increased by approximately 2 19 feet since October 14, 2002 A hydrograph of historic • groundwater elevations is attached as Figure 3 It should be noted that well screens for shallow monitor wells MW-1 through MW-8 were drowned CONDOR