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S EC ® R Page 2 to depths ranging from approximately 135 to 140 feet bgs, and the installation of eight wells (MW-2 through MW-9) A report documenting the findings of the investigation was submitted on February 28, 2002 The report concluded that the petroleum hydrocarbon impact to sod decreased significantly below approximately 65 feet on-site, and that the vertical extent of petroleum hydrocarbon impact to sod was adequately assessed on-site Stratus directed the completion of an off-site subsurface investigation between February and June 2004 The investigation consisted of advancing four exploratory soil borings (B-39 through B-42), and completion of five monitoring wells (MW-10, and MW-12 through MW-15) Well VW- 15 was also destroyed at this time Results of the investigation were presented in a document titled Subsurface Assessment Report and Site Conceptual Model Update (September 3, 2004) Given the findings of this investigation, the lateral extent of petroleum hydrocarbon impact to sod and groundwater is not fully characterized south-southeast of the site Information regarding historical sod borings completed at the site, and details regarding the well installations, are summarized in Table I and Table 2 Location of all soil borings and monitoring wells are included on Figure 2 ARCO upgraded the product lines and product dispensers in January and February 2002 Approximately 315 tons of petroleum hydrocarbon impacted soil was excavated and removed from the site at this time lateral conveyance piping for future use in soil vapor extraction was • connected to wells VW- 1, VW-3, VW-4, VW-6, VW-7, VW-8, VW- 11 through VW-14, VW-16, and MW-2 through MW-9 at the time of the site renovation The conveyance piping was stubbed up at the northwest comer of the property to be manifolded for connection to a sod vapor extraction (SVE) system at a later date, if warranted Continuous SVE was completed at the site between March and November 2004, using two 200 cubic feet per minute (cflm) King, Buck & Associates, Inc electric catalytic oxidizers equipped with 7 5 horsepower blowers An estimated mass of 9,625 pounds of TPHG was removed from the subsurface using the electric catalytic oxidizers The SVE system was upgraded in May 2005, with a Solleco 500 cflm thermal catalytic oxidizer This Solleco SVE system is currently extracting soil vapors from wells VW-I VW-3, VW-4, VW-8, VW- 14, MW-2, MW-8, and MW-9 As of June 14, 2005, an estimated mass of 4,338 pounds of TPHG has been removed from the subsurface using the 500 cflm thermal oxide A water supply well was installed in the southwestern corner of the property in 1969 and currently supplies water to the service station The well was constructed of 8-inch diameter casing to 540 feet bgs, screened from 396 to 416 and 496 to 536 feet bgs, and gravel packed from 35 to 540 feet bgs (The IT Group, September 10, 1999) Reportedly, a sanitary seal was not installed Water samples have been collected from this well on a periodic basis since August 1999 Petroleum hydrocarbon and fuel additive concentrations have consistently been reported below laboratory detection limits