|
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, (ASB1,
<br />MW4, MW5, MW6, MW7, SB8, and SB9) at the site to depths ranging from approximately 26.5 to
<br />62 feet bgs. These borings were advanced to: 1) evaluate the horizontal and vertical extent of
<br />petroleum hydrocarbon impacted soil and groundwater; 2) evaluate and refine soil stratigraphy; and
<br />3) install groundwater monitoring wells (MW4, MW5, MW6, and MW7) within the uppermost
<br />aquifer. Groundwater samples collected from MW5, MW6, and MW7 contained elevated
<br />concentrations of TPHg and benzene. Field activities and analytical results were detailed in ATC's
<br />Summary Report of Subsurface Investigation, dated August 14, 1998.
<br />In November 1999, ATC personnel supervised the advancement of three soil borings, SB9A, SB10,
<br />and SB11. SB10 and SB11 were advanced to 46 feet bgs using hollow stem auger techniques and
<br />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
<br />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 viable remedial options for
<br />impacted soil and groundwater at the site. Specifically this included evaluation of whether vapor
<br />extraction could sufficiently capture air sparge off-gas, evaluation of short-term VOC flux rates, and
<br />collection of data to design a vapor extraction/air sparge system. The results of the pilot test are
<br />detailed in ATC's Vapor Extraction and Air Sparge Pilot Test Results and Feayibility Study at the
<br />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
<br />were completed as SVE wells, and two as AS wells. Field activities and analytical results were
<br />detailed in ATC's Final Remediation Plan, Farmer Property, 610 North Hunter Street, Stockton,
<br />California, dated March 27, 2002.
<br />Additionally, in December 2001, an ATC geologist supervised the advancement of five Geoprobe
<br />borings, SB12 to SB16 to a depth of approximately 25 feet bgs. Three additional offsite borings
<br />were advanced to depths of approximately 42 feet bgs and completed as groundwater monitoring
<br />wells, MW8 through MW10. Field activities and analytical results were detailed in ATC's Offsite
<br />Subsurface Investigation Report, dated April 24, 2003.
<br />In December 2003, ATC implemented remedial activities at the site. The remedial activities consisted
<br />of soil vapor extraction (SVE) coupled with air sparging (AS). The SVE system was designed to utilize
<br />up to five extraction wells (VW1 through VW4 and MW1) and the AS system was designed to utilize
<br />up to two AS wells (AS1 and AS2). The current SVE system consists of a 300 actual cubic feet per
<br />minute (ACFM) thermal oxidizer. The AS system consists of a GAST 2567-P132-T908X rotary
<br />vane, 2- horsepower, air compressor. This blower is capable of injecting at a maximum of 20 pounds
<br />HASP Level III
<br />Rev. 01 — June 11,2007 2-2
|