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Site Background
<br /> ' Prior to 1979, two of the tanks(USTs#6 and#7)were removed from the site.
<br /> On June 15, 1995, Fisch Environmental removed a 12,000-gallon gasoline tank (UST #3) from the area
<br /> ' immediately west of the dispenser islands, and collected soil samples for laboratory analysis from beneath
<br /> the former UST. On June 29, 1995, based on the soil sample results, Fisch Environmental over-excavated
<br /> the tank basin to a depth of approximately 27 feet and collected additional soil samples. The over-
<br /> excavation soil samples also contained elevated concentrations of Total Petroleum Hydrocarbons (TPH)-
<br /> as-gasoline, and benzene, toluene, ethyl benzene and xylenes (BTEX).
<br /> During November 1998, the county public works department replaced USTs #1 and #2 with upgraded
<br /> systems. Advanced GeoEnvironmental collected soil samples from beneath the USTs and underground
<br /> product piping.
<br /> ' During March 1999,Tait Environmental Management (Tait) supervised the removing of UST#4, in-place
<br /> abandoning of UST #8,and soil and/or groundwater sampling from two hand-auger soil borings (HA-1
<br /> and HA-2), two truck-drilled soil borings (5-3 and SB-3), and two groundwater monitoring wells (MW-1
<br /> ' and MW-2). The well construction and groundwater monitoring data are summarized in Table C, and the
<br /> groundwater analytical results are summarized in Table A. Tait documented the project results in Site
<br /> Assessment Report, dated May 11, I999.
<br /> ' On July 13, 2000, Tait completed a water well survey for the site vicinity. Tait identified nine water wells
<br /> within 2,000 feet of the site, including the municipal irrigation well at Stribley Park.
<br /> ' On February 7, 2002, Ramage Environmental published Monitoring Well Installation and Groundwater
<br /> Monitoring Report, which documented the installation of one additional monitoring well (MW-3), which
<br /> is shown on Figure 2. The well construction details and groundwater monitoring data are summarized in
<br /> Table C, and the groundwater analytical results are included in Table A.
<br /> On March 7, 2003, Ramage Environmental published Site Conceptual Model and Work Plan, Additional
<br /> Site Investigation and Remedial Feasibility Testing. On July 14,2003, EHD approved the work plan.
<br /> Also on March 7, 2003, Ramage Environmental installed a passive free product skimmer in MW- 1, and
<br /> ' initiated periodic free product removal site visits. Between March 7, 2003 and December 12, 2006, after
<br /> 54 site visits, Ramage Environmental removed approximately 221.45 ounces of accumulated free product
<br /> from the skimmer, and apparently eliminated the free product from the groundwater surface.
<br /> ' On December 1, 2003, to further define the plume of impacted groundwater, Ramage Environmental
<br /> installed three additional on-site groundwater monitoring wells (MW-4, MW-5 and MW-6). The well
<br /> ' locations are shown on Figure 2, Appendix A, groundwater monitoring data are included in Table A,
<br /> Appendix B, and the well construction details are included in Table C, Appendix B. Ramage
<br /> Environmental documented the results of the investigation in Monitoring Well Installation and
<br /> ' Groundwater Monitoring Report, dated January 16, 2004.
<br /> On May 20, 2005, Ramage Environmental published Well Installation and Groundwater Monitoring
<br /> Report, which documented the installation of one additional groundwater monitoring well (MW-7) and
<br /> ' two remedial feasibility test wells (SVE-1A/B/C and AS-1/SVE-2B).
<br /> Ramage Environmental continued to conduct quarterly groundwater sampling and publishing
<br /> ' groundwater monitoring reports through the second quarter of 2010.
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