Laserfiche WebLink
/AnEE <br /> GEOMATRIX <br /> TEPH using EPA Method 8015M quantified against a diesel standard. Prior to the TEPH <br /> analysis, a silica gel clean-up was performed on the sample extract to remove polar biogenic <br /> material (non-petroleum hydrocarbons) that may interfere with analytical results. All <br /> groundwater samples were analyzed by AEN with the exception of the EPA Method 8310 <br /> analysis, which was performed by CLS Laboratories of Rancho Cordoba, California. <br /> 4.0 ADDITIONAL ASSESSMENT RESULTS <br /> This section presents results of data collected during the additional assessment activities in <br /> March, June, and July 1997. Boring and well logs are presented in Appendix A and PHS-EHD <br /> permits are presented in Appendix B. Soil and groundwater analytical results are summarized <br /> in Tables 1 through 4. Laboratory data sheets and chain-of-custody records are included in <br /> Appendix C. <br /> 4.1 SITE HYDROGEOLOGY <br /> Based on borings advanced to date by Geomatrix, the site is underlain by a silty sand from <br /> ground surface to approximately 3 feet bgs, followed by a lean clay to 7.5 feet bgs, and poorly <br /> graded sand and silty sand to approximately 25 feet bgs. Depth to groundwater at the site is <br /> approximately 12 feet bgs. Direction of groundwater flow at the site is unknown; however, it is <br /> anticipated to be to the north (personal communication, PHS-EHD Staff, 21 March 1997). <br /> 4.2 SOIL AND GROUNDWATER ANALYTICAL RESULTS <br /> No visual or olfactory evidence of petroleum hydrocarbons was observed during drilling and <br /> sampling of borings SB-2 and SB-3 or temporary well TW-1. In addition, field screening of <br /> soil samples using a PID did not indicate the presence of petroleum hydrocarbons. PID <br /> measurements are recorded on boring and well logs (Appendix A). <br /> Soil samples collected from borings SB-2, SB-3, and well TW-1 did not contain detectable <br /> concentrations of BTEX or TEPH (Table 3). The dark inclusions observed in the sample <br /> collected from boring SB-2 at a depth of 10.5 feet bgs were probably due to fragments of <br /> organic-rich sediments. Relatively low concentrations of certain PAHs were detected in both <br /> 1:\WPD0CS\4097\ADDLINVB.D0C 7 <br />