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f ! ATC Associates Inc.
<br /> TC 1117 Lone Palm Avenue, Suite 201
<br /> (YVAModesto, California 95351
<br /> 209-579-2221
<br /> fax: 209-579-2225
<br /> contamination. Three of the soil borings were completed as groundwater monitoring wells and
<br /> two of the soil borings were completed as vapor extraction wells. The soil boring, groundwater
<br /> monitoring well, and vapor extraction well locations are shown on Figure 2 . On July 3 , 1997,
<br /> the monitoring wells were developed and sampled for petroleum hydrocarbons along with the
<br /> adjacent property owner's well (CW) . The samples from MWI , MW2, and MW3 contained
<br /> elevated concentrations of petroleum hydrocarbons. Field activities and analytical results were
<br /> ! 1 detailed in Smith Technology' s Summary Report dated September 17, 1997.
<br /> On March 24 and 25, 1998, ATC personnel supervised advancement of seven soil borings,
<br /> (ASB1 , MW4, MW5, MW6, MW7, SB8, and SB9) at the site to depths ranging from
<br /> approximately 26.5 to 62 feet bgs. These borings were advanced to; 1 ) evaluate the horizontal
<br /> and vertical extent of petroleum hydrocarbon impacted soil and groundwater; 2) evaluate and
<br /> refine soil stratigraphy; and 3) install groundwater-monitoring wells (MW4, MW5, MW6, and
<br /> !- J MW7) within the uppermost aquifer. Groundwater samples collected from MW5, MW6, and
<br /> MW7 contained elevated concentrations of TPHg and benzene. Field activities and analytical
<br /> results were detailed in ATC 's Summary Report of Subsurface Investigation, dated August 14,
<br /> ! 1998 .
<br /> In November 1999, ATC personnel supervised the advancement of three soil borings, SB9A,
<br /> SB 10, and SB 11 . SB 10 and SB I 1 were advanced to 46 feet bgs using hollow stem auger
<br /> techniques and SB9A was advanced to 65 feet bgs using continuous core methods . Field
<br /> activities and analytical results were detailed in ATC 's Summary Report of Groundwater and
<br /> Soil Investigation, dated July 16, 1999.
<br /> In March 2000, ATC personnel performed a vapor extraction and air sparge pilot test at the site.
<br /> The purpose of these tests was to evaluate vapor extraction and air sparging as viable remedial
<br /> options for impacted soil and groundwater at the site. Specifically this included evaluation of
<br /> — whether vapor extraction could sufficiently capture air sparge off-gas, evaluation of short-term
<br /> VOC flux rates, and collection of data to design a vapor extraction/air sparge system. The
<br /> results of the pilot test are detailed in ATC' s Vapor Extraction and Air Sparge Pilot Test Results
<br /> and Feasibility Study at the Farmer Property, 610 North Hunter Street, Stockton, California, dated
<br /> November 2, 2000,
<br /> In December 2001 , an ATC geologist supervised the advancement of five soil borings to depths
<br /> of approximately 42 feet bgs and two soil borings to depths of approximately 26 feet bgs. Three
<br /> of the seven soil borings were completed as groundwater monitoring wells. Of the remaining
<br /> borings, two were completed as SVE wells, and two as AS wells. Field activities and analytical
<br /> results were detailed in ATC ' s Final Remediation Plan, Farmer Property, 610 North Hunter
<br /> Street, Stockton, California, dated March 27, 2002 .
<br /> Additionally, in December 2001 , an ATC geologist supervised the advancement of five
<br /> Geoprobe borings, S1312 to SB16 to a depth of approximately 25 feet bgs. Three additional
<br /> offsite borings were advanced to depths of approximately 42 feet bgs and completed as
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