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Project 113-13 February 7,1995 Page 4 Table 2 Cheaper! #76, 890 North Main Street, Manteca, California Groundwater Sample Analysis Results* Samples Collected on January 25, 1995 Sample # TPH-g Benzene Toluene Eth lbenzene Xylenes MW-1 ND < 50 ND <0.5 ND <0.5 ND <0.5 ND <0.5 MW-2 ND < 50 1.3 091 ND <0.5 0.79 MW-3 ND < 50 ND <0.5 ND <0 5 ND <0.5 ND <0.5 MW-4 ND < 50 ND <0.5 ND <0.5 ND <0.5 ND <0 5 Sample results are in µg/L or parts per billion. The sample analyses show that total petroleum hydrocarbons as gasoline and ethylbenzene were not detected in groundwater at the well locations. Benzene, toluene, and xylenes were detcted in MW-2 only (see Figure 3 - Hydrocarbon Concentration Map) The California Department of Health Services has established MCLs (Maximum Contaminant Levels) for benzene, ethylbenzene, aand xylenes. The U.S. EPA has established primary and secondary levels for BTEX. These are compared with the MW-1, MW-2, and MW-3 results below. Table 3. Comparison of January 25, 1995, Sample Results With Current Action Levels Sample TPH-g Benzene Toluene Ethylbenzene Xylenes MW-2 ND<50 1.3 091 ND<0.5 079 DOHS MCL NA 1 NA 680 1,750 US EPA Pnmary NA 5 1,000 700 10,000 US EPA Secondary NA NA 40 30 20 May, 1993, update TPH and BTEX are in ppb or pg/L NA = Not Applicable Concentrations above the action levels are in boldface M Future Directions The six previous quarters found all wells to be ND for TPH-g and BTEX. Following the groundwater level rise, a small concentration of benzene (1.3 ppb) was found in January, 1995. Parker Environmental recommends that The Customer Company pursue site closure with the San Joaquin County Department of Health Services. Parker Environmental Services 190 East 7th Street Pittsburg CA 94565-6116 Phone (510) 439-1024 Fax (510) 439-2566