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6.0 LABORATORY ANALYSES - WATER <br />Groundwater samples were collected from monitoring wells CPMW1, <br />CPMW2, and CPMW3 after stabilization of electrical conductivity, <br />pH, and temperature. Samples were analyzed for BTEX using EPA <br />method 602, TPHG and TPHD using modified EPA method 8015, and <br />coliform bacteria by DHS LUFT methodology. <br />Coliform bacteria analysis was conducted at the request of the San <br />Joaquin County regulator on site because of a suspected sewage <br />contamination problem which is unrelated to this petroleum <br />hydrocarbon investigation. <br />Nondetectable levels of petroleum hydrocarbons were detected in the <br />groundwater of the most down gradient well CPMW1 and cross gradient <br />monitoring well CPMW3. Benzene, toluene, ethylbenzene, xylene and <br />TPHG were detected in monitoring well CPMW2, which is currently the <br />up -gradient well. A summary of laboratory analysis is presented <br />in Table 3. Laboratory reports with chain -of -custody documents are <br />presented in Appendix IV. <br />Table 3. Corrigan Property, laboratory analysis water - March 28, 1991. <br />NOTES <br />TPHG Q Total Petroleum Hydrocarbons as Gasoline by Modified EPA Method 8015 <br />TPHD - Total Petroleum Hydrocarbons as Diesel by Modified EPA Method 8015 <br />Benzene toluene ethylbenzene and xylenes by EPA Method 8020/602 <br />ND - Not Detected Compound(s) may be present at concentrations below the detection limit <br />NA . Not available <br />Results in pg/1 - ppb = parts per billion <br />* - Results in MPN/100 ml <br />7.0 PROPOSED ADDITIONAL ASSESSMENT <br />WaterWork proposes to complete the following worksteps to provide <br />additional information regarding subsurface conditions at the <br />facility to address remediation of the petroleum hydrocarbon plume <br />present in the vadose zone, and verify the groundwater gradient at <br />the site. A remediation option will be designed based on <br />information provided from this investigation. <br />10 Corrigan property - 381 <br />R0691 TLP 5 <br />Uazzn <br />TOTAL <br />CPMWl <br />ND <br />ND <br />ND <br />ND <br />ND ND (2 2 <br />CPMW2 <br />8 6 <br />13 <br />16 <br />41 <br />800 ND >16 0 <br />CPMW3 <br />ND <br />ND <br />ND <br />ND <br />ND ND 5 1 <br />DETECTION <br />LIMIT <br />0 50 <br />J__ <br />5 <br />- 1 <br />0 5 <br />0 5 <br />50 100 NA <br />7 1 <br />NOTES <br />TPHG Q Total Petroleum Hydrocarbons as Gasoline by Modified EPA Method 8015 <br />TPHD - Total Petroleum Hydrocarbons as Diesel by Modified EPA Method 8015 <br />Benzene toluene ethylbenzene and xylenes by EPA Method 8020/602 <br />ND - Not Detected Compound(s) may be present at concentrations below the detection limit <br />NA . Not available <br />Results in pg/1 - ppb = parts per billion <br />* - Results in MPN/100 ml <br />7.0 PROPOSED ADDITIONAL ASSESSMENT <br />WaterWork proposes to complete the following worksteps to provide <br />additional information regarding subsurface conditions at the <br />facility to address remediation of the petroleum hydrocarbon plume <br />present in the vadose zone, and verify the groundwater gradient at <br />the site. A remediation option will be designed based on <br />information provided from this investigation. <br />10 Corrigan property - 381 <br />R0691 TLP 5 <br />