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16� <br />Ms Lori Duncan <br />October 28, 2004 <br />1 Page 2 <br />ProjectNo 880-039 1A 01010000 <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 />• 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 THIRD QUARTER 2004 <br />On August 9, 2004, a Shaw technician was on-site to measure depth to groundwater and <br />collect groundwater samples from wells MW -1R through MW -4R (S and D), and VW -1D <br />through VW -4 for laboratory analyses Shaw coordinated joint quarterly sampling with the <br />adjacent service station sites Free product was not observed in groundwater monitoring <br />wells (see Table 1 and Appendix A) Shaw used the third quarter 2004 data to evaluate <br />changes in concentrations of dissolved petroleum hydrocarbons in the groundwater Shaw <br />sampling and analysis procedures are presented in Appendix B <br />N IsacDP120041Prj188018800391A 4ad doc SHAW ENVIRONMENTAL, INC <br />