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1 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 parts per billion (ppb) to 130,000 ppb and 920 to 11,000 ppb,
<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 1, MW4,
<br /> MW5, MW6, MW7, SBS, and SB9, 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 define 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, SB9A, SB 10, and
<br /> SB 11 Borings SB 10 and SB 1 I were advanced to 46 feet bgs using hollow stem auger techniques and
<br /> boring SB9A was advanced to 65 feet bgs using continuous core methods Field activities and analytical
<br /> ' results were detailed in ATC's Summary Report of Groundwater and Soil Investigation, dated July 16,
<br /> 1999
<br /> M 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 viable remedial options for
<br /> impacted soil and groundwater at the site and to evaluate whether vapor extraction could sufficiently
<br /> ' capture air sparge off-gas, to evaluate short-term volatile organic compound (VOC) flux rates, and to
<br /> collect data to design a vapor extraction/air sparge system The results of the pilot test are detailed in
<br /> ATC's Vapor Extraction and Air Sparge Pilot Test Results and Feasibility Study at the Farmer Property,
<br /> 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, SB 12 to SB 16 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 MWIO 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 September 14 2004, ATC personnel collected groundwater samples from MW 1 through MW 10,
<br /> VWI, VW2, and CW The locations of the monitoring wells are shown on Figure 2 Prior to collection
<br /> of groundwater samples, the depth to water was measured in the wells, the pH, electrical conductivity,
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