Laserfiche WebLink
r <br /> ;�' 'VASSOCIATES INC <br /> and groundwater samples contained detectable concentrations of petroleum hydrocarbons Field <br /> activities and analytical results were detailed in ATC's Summary Report of Additional Subsurface <br /> Investigation, dated January 8, 1999 <br /> Two additional groundwater monitoring events were performed by ATC in April and July 1999 <br /> ' Concentrations of petroleum hydrocarbons in groundwater generally increased during these two <br /> events The increase may have been a result of seasonal groundwater elevation changes <br /> 2.4 METHODS AND PROCEDURES <br /> To evaluate the lateral and vertical extent of petroleum impacted soil and groundwater in the <br /> vicinity of the former UST, three soil bongs were advanced at the locations shown on Figure 2 <br /> All field activities were performed in accordance with ATC's Workplan for Additional Subsurface <br /> ' Investigation at Diesel Performance, 2804 East Fremont Street, Stockton, California, dated <br /> November 3, 1999 This workplan was approved by PHS/EHD on November 8, 1999 <br /> 221 Soil Borine Advancement and Sam lin <br /> On December 14 and 15, 1999, ATC supervised the advancement of three soil borings at the site <br /> to depths of approximately 65 feet bgs Drilling was conducted by V & W Drilling (State C57 <br /> license no 720904) utilmng a hollow stem auger dnll ng Soil bongs MW2, MW3, and MW4 <br /> were advanced and completed as groundwater monitoring wells A field geologist logged drill <br /> cuttings and soil samples utilizing the Unified Soil Classification System Descriptions of soil <br /> types encountered and sample collection intervals are included on the well logs contained in <br /> Appendix A <br /> ' The cored soil samples were collected at five-foot intervals using a 2-inch diametersplit-spoon <br /> sampler containing three brass tubes The cored samples and drill cuttings were characterized for <br /> ' soil type, moisture content, and visual evidence of petroleum hydrocarbons A flame ionization <br /> detection meter (FID) was used as a field-screening device for the detection of petroleum <br /> hydrocarbon vapors in drill cuttings and cored samples Drill cuttings were temporarily stored on <br /> ' site in 55-gallon DOT approved steel drums <br /> 222 Soil Sample Analysis <br /> Soil samples were placed on ice, and transported under chain-of-custody to Sequoia Analytical <br /> (FLAP #1210) of Morgan Hill, California for analysis All soil samples were analyzed for total <br /> petroleum hydrocarbons as gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), <br /> total petroleum hydrocarbons as kerosene (TPHk), benzene, toluene, ethylbenzene, and xylenes <br /> 1 (BTEX) utilizing EPA 8015 and 8020 methodologies, and oxygenate fuel additives utilizing EPA <br /> 8260 methodology The analytical results for soil samples are summarized in Table 1 Laboratory <br /> data sheets and chain-of-custody documentation are included in Appendix C <br /> W\62577Tcp«,S\sum,i dw 2 <br />