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,WSW, SITE HISTORY 1994 Underground Storag Tank (UST) Removal. During December 1994, four single-walled steel USTs (two 5,000-gallon, one 7,000-gallon, and one 8,000-gallon) and associated product piping were removed. Petroleum hydrocarbons were detected in soil samples collected from the former UST excavation. Over-excavation was performed and additional soil samples were collected. One soil sample collected from the excavation sidewall at 14 feet below grade (fbg) contained 380 milligrams per kilogram (mg/kg) total purgeable petroleum hydrocarbons as gasoline (TPHg). Two soil samples collected at depths of 4.5 and 6 fbg from the dispenser island areas contained 1,600 and 1,700 mg/kg TPHg. Complete results of the UST removal are documented in the Fugro West,Inc. April 19,1995 Underground Storage Tank Closure Report. 1996 Site Investigation: During February 1996, Enviros, Inc. (Enviros) drilled 10 soil borings in the vicinity of the UST complex and the dispenser islands. TPHg was detected in three of the borings at concentrations up to 770 mg/kg. Benzene was detected in one boring at concentrations ranging from 0.0082 to 0.026 mg/kg. Methyl tertiary butyl ether (MTBE) was detected in four of the borings at concentrations up to 15 mg/kg. Enviros' May 21,1996 Soil Boring Installation Report details this investigation. 1999r-VVWIFI;nis�tallat�ion: uring September 1999, Cambria installed one groundwater monig well (MW-1). oil samples from well boring MW-1 contained 0.0208 mg/kg o TPHg, ben7Zne, toluene, ethylbenzene, and xylenes (BTEX), fuel oxygenates other then MTBE, or lead scavengers were detected in soil from this boring. Cambria's December 21, 1999 Site Investigation/Fourth Quarter 1999 Groundwater Monitoring Report further describes this investigation. 2001 Piping Replacement. During March 2001, the site's product piping was removed and replaced. Cambria collected eight soil samples beneath the piping. Six of the samples contained TPHg up to 220 mg/kg. Benzene was detected in three of the soil samples at concentrations up to 0.066 mg/kg. MTBE was detected (by EPA Method 8260B) in all soil samples at concentrations ranging from 0.015 to 0.42 mg/kg. Tertiary amyl methyl ether (TAME) and tertiary butanol (TBA) were also detected in some of the soil samples at low concentrations. These activities are summarized in Cambria's August 1,2001 Soil Sampling and Piping Removal Report. 2001 Well Installation: Dur' g November 2001, Cambria drilled one cone penetration test (CPT) boring (CPT-1) d installed three groundwater monitoring wells MW-3,and MW-4). Soil mples from the well borings did not contain detectable TPHg, or MTBE co ntrations. Soil samples from the CPT boring contained MTBE (up 241359(6)