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<br /> for petroleum hydrocarbons along with the adjacent property owner's well (CW). The samples from
<br /> MW 1, MW2, and MW3 contained concentrations of total petroleum hydrocarbons as gasoline (TPHg)
<br /> and benzene ranging from 3,200 micrograms per liter (ug/l) to 130,000 ug/l and 920 to 11,000 ug/l,
<br /> respectively. Field activities and analytical results were detailed in Smith Technology's Summary Report
<br /> dated September 17, 1997.
<br /> On March 24 and 25, 1998, ATC personnel supervised advancement of seven soil borings, ASB I, MW4,
<br /> MW5, MW6, MW7, S138, and S139, at the site to depths ranging from approximately 26.5 to 62 feet bgs.
<br /> These borings were advanced to: 1) evaluate the horizontal and vertical extent of petroleum hydrocarbon
<br /> impacted soil and groundwater; 2) evaluate and refine soil stratigraphy; and 3) install groundwater
<br /> monitoring wells (MW4, MW5, MW6, and MW7) within the uppermost aquifer. Groundwater samples
<br /> collected from MW5, MW6, and MW7 contained elevated concentrations of TPHg and benzene. Field
<br /> activities and analytical results were detailed'in ATC's Summary Report of Subsurface Investigation,
<br /> dated August 14, 1998.
<br /> In November 1999, ATC personnel supervised the advancement of three soil borings, S139A, S1310, and
<br /> SBI 1. S1310 and SBI I were advanced to 46 feet bgs using hollow stem auger techniques and SB9A was
<br /> advanced to 65 feet bgs using continuous core methods. Field activities and analytical results were
<br /> detailed in ATC's Summary Report of Groundwater and Soil Investigation, dated July 16, 1999.
<br /> In March 2000, ATC personnel performed a vapor extraction and air sparge pilot test at the site. The
<br /> purpose of these tests was to evaluate vapor extraction and air sparging as remedial options for impacted
<br /> soil and groundwater at the site. Specifically this included an evaluation of whether vapor extraction
<br /> could sufficiently capture air sparge off-gas, an evaluation of short-term volatile organic compound
<br /> (VOC) flux rates, and collection of data to design a vapor extraction/air sparge system. The results of the
<br /> pilot test are detailed in ATC's Vapor Extraction and Air Sparge Pilot Test Results and Feasibility Study at
<br /> the Farmer Property, 610 North Hunter Street, Stockton, California,dated November 2, 2000,
<br /> In December 2001, an ATC geologist supervised the advancement of five soil borings to depths of
<br /> approximately 42 feet bgs and two soil borings to depths of approximately 26 feet bgs. Three of the
<br /> seven soil borings were completed as groundwater monitoring wells. Of the remaining borings, two were
<br /> completed as SVE wells, and two as AS wells. Field activities and analytical results were detailed in
<br /> ATC's Final Remediation Plan, Farmer Property, 610 North Hunter Street, Stockton, California, dated
<br /> March 27, 2002.
<br /> Additionally, in December 2001, an ATC geologist supervised the advancement of five Geoprobe
<br /> borings, S1312 to SB16 to a depth of approximately 25 feet bgs. Three additional offsite borings were
<br /> advanced to depths of approximately 42 feet bgs and completed as groundwater monitoring wells, MW8
<br /> through MW10. Field activities and analytical results were detailed in ATC's Offsite Subsurface
<br /> Investigation Report, dated April 24, 2003.
<br /> QUARTERLY GROUNDWATER MONITORING ACTIVITIES
<br /> On December 6 2004, ATC personnel collected groundwater samples from MW 1 through MW 10, VW 1,
<br /> VW2, and CW. The locations of the monitoring wells are shown on Figure 2. Prior to collection of
<br /> . groundwater samples, the depth to water (DTW) was measured in the wells. The pH, electrical
<br /> conductivity, and temperature were measured in groundwater purged from the monitoring wells, and
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