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Ms Lori Duncan Project No 880-039 IA 01010000 <br /> August 2, 2004 <br /> Page 2 <br /> Colombo bakery Based on data collected from subsurface investigations performed at <br /> the former ARCO Service Station, Chevron Station, and Texaco Station (located at the <br /> corners of Charter Way and Lincoln Street), residual and dissolved hydrocarbons have <br /> been detected beneath those 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 <br /> extraction well VW-4 (EMCON, Preliminary Investigation and Evaluation Report, <br /> February 5, 1997) The results of this investigation indicate the following <br /> • With the exception of soil samples collected from boring B-6R, residual <br /> hydrocarbons were reported in each boring The highest petroleum <br /> hydrocarbon concentrations were reported at approximately 10 feet below <br /> ground surface (bgs) near the former USTs Total Oil and Grease were reported <br /> in the soil sample collected near the former UST cavity (located near the <br /> building) at a concentration of 10,000 parts per million (ppm) Polychlorinated <br /> biphenyls, TPHd, or chlorinated hydrocarbons were not detected in soil samples <br /> analyzed from soil borings B-2R and B-6R <br /> o TPHg, benzene, toluene, ethylbenzene, and total xylenes (BTEX), and methyl <br /> tert-butyl ether (MTBE) were reported in the groundwater sample collected <br /> ' from monitoring well MW-1R TPHg and benzene were reported at <br /> concentrations of 33,000 and 1,400 parts per billion (ppb), respectively MTBE <br /> was reported at a concentration of 550 ppb <br /> GROUNDWATER MONITORING SECOND QUARTER 2004 <br /> On May 10, 2004, a Shaw technician was on-site to measure depth to groundwater and <br /> collect groundwater samples from wells MW-1R, MW-3R through MW-4R (S and D), and <br /> VW-1D through VW4 for laboratory analyses Shaw coordinated joint quarterly sampling <br /> with the adjacent service station sites Free product was not observed in groundwater <br /> monitoring wells (see Table 1 and Appendix A) Shaw used the second quarter 2004 data <br /> to evaluate changes in concentrations of dissolved petroleum hydrocarbons in the <br /> groundwater Shaw sampling and analysis procedures are presented in Appendix B <br /> 1 <br /> N 1sacDP120041Pg18801880039tA 4ac doc SHAW ENVIRONMENTAL,INC <br />