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1995 Site Investigation: During July 1995, PEG installed well MW-28 and deep well DW-2 (PEG, <br /> October 30, 1995). Low level TPHd concentrations were detected in both wells. TPHg and BTEX <br /> constituents were detected in well DW-2 only. <br /> Summary of Investigation Activities through 1996: Between 1985 and 1995, 28 shallow zone <br /> monitoring wells and 2 deep monitoring wells were installed. Deep well DW-1 was destroyed prior to <br /> November 1995 due to concern of poor well construction and replaced with well DW-2. The wells were <br /> sampled for TPHg,TPHd, BTEX and total lead. <br /> Historically, groundwater has ranged from approximately 10 to 15 tbg. SPH has been present beneath <br /> the site in all three secondary source areas. Historically, the greatest SPH thickness has been observed in <br /> well MW-10 (0.80 foot). The occurrence and thickness of SPH has steadily declined since startup of the <br /> remedial system in 1994. SPH was reported in two wells during the fourth quarter 1996 event;well MW- <br /> 10 contained 0.19 foot and well MW-13 contained 0.23 foot. <br /> The site investigation work appeared to have adequately characterized soil and groundwater conditions, <br /> and the horizontal and vertical extent of the plume was also adequately defined. <br /> 2000 through 2002 Well Installations:Limited information was available for this time period. Based on <br /> previous consultant's records, TOXICHEM installed wells MW-29 through MW-34. During October <br /> 2000, wells MW-29 and MW-30 east of tank farm near the former railcar unloading spur. During July <br /> 2001, wells MW-31 and MW-32 were installed east and northeast of wells MW-29 and MW-30 to <br /> provide offsite plume definition. Additionally, well MW-33 was installed to provide plume definition <br /> downgradient and southwest of the former unlined holding pond. During April 2002, well MW-34 was <br /> installed to provide plume definition downgradient of the site near Hooper Drive and well MW-28. <br /> 2003 Investigation Activities: During March 2003,RETEC performed a direct push and well installation <br /> investigation to delineate the extent of petroleum constituents west of well MW-33 (RETEC, May 16, <br /> 2003). Ten direct push borings were installed and depth discrete groundwater samples were collected. <br /> Based on the groundwater analytical data, well MW-35 was installed. The investigation findings <br /> concluded that with the exception of low levels of TPHd, DIPE, TBA, and ethanol the plume west of <br /> well MW-33 was defined. <br /> 2004 Investigation Activities: During October 2004, RETEC performed a direct push and well <br /> installation investigation to delineate the extent of petroleum constituents near well MW-35 (RETEC, <br /> January 14, 2005). Ten direct push borings were installed and depth discrete groundwater samples were <br /> collected near well MW-35. Based on the groundwater analytical data, well MW-36 was installed. The <br /> 1729 3 <br />