Laserfiche WebLink
Mr John Benedict Project 880039 IA <br /> October 25, 2001 <br /> Page 2 <br /> collected from subsurface investigations performed at the former ARCO Service Station, <br /> Chevron Station, and Texaco Station (located at the corners of Charter Way and <br /> Lincoln Street), residual and dissolved hydrocarbons have been detected beneath these <br /> facilities <br /> Between September 17 and October 11, 1996, EMCON/OWT observed the drilling of <br /> six soil borings (B-1R through B-6R) One soil boring was converted to monitoring well <br /> MW-1R, three soil borings were converted to dual completion vapor extraction wells <br />' VW-1 through VW-3, and one soil boring was converted to a single vapor extraction <br /> well VW-4 (EMCON, Preliminary Investigation and Evaluation Report, <br />' February 5, 1997) The results of this investigation indicated the following <br /> • With the exception of soil samples collected from boring B-6R, residual <br />' hydrocarbons were detected in each boring The highest concentrations were <br /> detected approximately 10 feet below ground surface (bgs) near the former <br /> USTs Total oil and grease was detected in the soil sample collected near the <br />' • former UST cavity (located near the building) at a concentration of 10,000 parts <br /> per million Polychlorinated biphenyls, TPH-d, and chlorinated hydrocarbons <br /> were below laboratory detection limits in all soil samples analyzed from soil <br />' borings B-2R and B-6R <br /> • TPH-g, benzene, toluene, ethylbenzene, and total xylenes (BTEX) isomers, and <br />' methyl tert-butyl ether (MTBE) were detected in the groundwater sample <br /> collected from monitoring well MW-1R TPH-g and benzene were detected at <br /> concentrations of 33,000 parts per billion (ppb) and 1,400 ppb, respectively <br /> MTBE was detected at a concentration of 550 ppb <br />' GROUNDWATER MONITORING: SECOND QUARTER 2001 <br /> On May 17, 2001, an IT technician was on-site to measure depth to groundwater and <br /> collect groundwater samples from wells MW-1R, VW-2, and VW3 for subjective and <br /> laboratory analyses The second quarter sampling was jointly conducted with the former <br /> ARCO facility 2168, located east and downgradient of the subject site Floating product <br />' was not observed in groundwater monitoring wells (see Table 1 and Appendix A) IT used <br /> these data to evaluate changes in concentrations of dissolved gasoline hydrocarbons in the <br />' groundwater IT's sampling and analysis procedures are presented in Appendix B <br />' SAC 111SACRFPt\COMMONlsacDP120011PRJ1PJ818800391A lac doc-011it I it coRPORarronr <br /> 1 <br />