Laserfiche WebLink
1 <br /> 4.2 Groundwater Monitoring Well Installation <br /> ' Based on subsurface conditions using an FID or PID and field observations, borings B-1, <br /> B-4, and B-5 were converted to groundwater monitoring wells MW-1 through MW-3, <br /> respectively. Borings B-1, B-4, and B-5 were drilled to depths of 75.6, 75.5, and 75.0 feet <br /> rbgs, respectively. The monitoring wells were installed to evaluate the groundwater flow <br /> direction and whether hydrocarbons were present in groundwater beneath the site. <br /> Monitoring well locations are shown on Figure 2. Well construction information is <br /> presented in Appendix B. <br /> ' 4.3 Vapor Extraction Well Installation <br />' Based on subsurface conditions using an FID or PID and field observations, borings B-3, <br /> B-7, and B-8 were converted to duel-completion vapor extraction wells VW-1 through <br /> VW-3, respectively. Borings B-3, B-7, and B-8 were drilled to depths of 62.6, 62.2, and <br /> 61.5 feet bgs, respectively. Well completion information is presented in Appendix B. <br /> 4.4 Well Development and Sampling <br /> On September 20, 1995, an EMCON technician measured depths to groundwater with an <br /> oil/water interface probe in wells MW-1 through MW-3. No floating product was <br /> observed; therefore, the wells were developed. Well development procedures are <br /> presented in Appendix A. <br /> On September 25, 1995, an EMCON technician measured depths to groundwater in the <br /> monitoring wells and collected groundwater samples for subjective and laboratory <br />' analyses of hydrocarbons. Floating product was not observed in the wells. Sampling and <br /> analysis procedures are presented in Appendix A. <br />' The groundwater purged during development and sampling was transported to EMCON's <br /> Sacramento facility and temporarily stored in a 3,000-gallon holding tank. On <br /> November 8, 1995, at ARCO's request, the purge water was then removed from <br />' EMCON's Sacramento facility by Integrated Waste Management for disposal. <br />' 4.5 Laboratory Analyses <br /> Select soil samples collected from borings B-1 through B-8 and the composite sample <br />' (SP-1) collected from the soil stockpile were submitted to Sequoia Analytical Laboratory <br /> in Sacramento, California, and analyzed for total petroleum hydrocarbons as gasoline <br /> (TPHG); and benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) using <br /> Modified Environmental Protection Agency (EPA) Methods 8015 and 8020, respectively. <br /> SAC\N:\PJ"805\08051470.I BS-95pa,:1 Rev.0.2/6/96 <br /> 0805-147.01 4-2 <br />