Laserfiche WebLink
W <br /> LO CHAPTER 4 <br /> FIELD AND ANALYTICAL RESULTS <br /> Lo <br /> To evaluate soil quality beneath ARCO Petroleum Products Company <br /> (ARCO) Service Station 2093, selected subsurface soil samples from <br /> each borehole were submitted to Brown and Caldwell' s (BC) California <br /> Department of Health Services (DHS) certified Emeryville <br /> laboratory. They were analyzed for benzene, toluene , and xylene <br /> �• (BTX) , (U.S. Environmental Protection Agency (EPA) Method 8020) ; <br /> total petroleum fuel hydrocarbons (EPA Method 8015 , modified) ; and <br /> purgeable halocarbons (EPA Method 8010) . One groundwater sample was <br /> collected from each monitoring well. Groundwaters were analyzed for <br /> BTX (EPA Method 602) , total petroleum fuel hydrocarbon, (EPA Method <br /> 8015) , purgeable halocarbons (EPA Method 601) , and total lead. <br /> Soil Quality <br /> Analytical results for selected soil samples are summarized in <br /> LW Table 4-1. Complete laboratory results are in Appendix F. EPA 8020 <br /> constituents are below California Regional Water Quality Control <br /> Board, Central Valley Region (Regional Board) action levels with the <br /> exception of sample ATR-4B, which has a benzene concentration of <br /> 2.2 milligrams per kilogram (mg/kg) . <br /> A trend of increasing BTX and total petroleum fuel hydrocarbon <br /> L' concentrations, in samples taken from the 10. 0- to 11. 5-foot <br /> interval, were noted in all the boreholes. It is thought that these <br /> increased concentrations in soils near the water table surface may be <br /> ►o due to a capillary fringe effect. EPA 8010 constituents were <br /> nondetectable in the soil samples analyzed. No standards have been <br /> established for total petroleum fuel hydrocarbons. <br /> Groundwater Quality <br /> On April 23 , 1987 , groundwater samples from the four monitoring <br /> 'i wells were collected by BC personnel and sent to BC' s Emeryville <br /> laboratory for analyses. Analytical results are summarized in <br /> Table 4--2. Complete laboratory reports are in Appendix F. <br /> BTX concentrations in wells ATR-3 and ATR-4 exceeded the DHS <br /> action levels. Dissolved benzene concentrations are shown on <br /> Figure 4-1. Total lead and 1, 2-dichloroethane concentrations <br /> exceeded Regional Board Primary Drinking Water Standards (MCL) in <br /> wells ATR-2 and ATR-3. No levels have been established for total <br /> petroleum hydrocarbons. <br /> L. <br /> Lo <br /> BROWN AND CALDWELL CONSULTING ENGINEERS <br /> ho <br />