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Site Background Information Chapin Brothers Investements, Inc <br /> Page 8 of 12 <br /> Soil samples collected from depths of 15, 20 and 25 feet bsg were analyzed <br /> REMEDIATION WELL INSTALLATION <br /> On 29 July 1997, three in-situ air-sparing (IAS) points (IAS-7 through IAS-9) were installed to <br /> depths of 25 and 15 feet bsg using AGE'S van-mounted Geoprobe 5400 soil probing machine Two <br /> probe borings were completed as IAS points using one 21-inch long, 3/8-inch 1 D stainless steel <br /> screen implant attached at 25 feet bsg to an anchor tip One additional probe boring was completed <br /> using one 21-inch long, 318-inch I D stainless steel screen implant set at a depth of 15 feet bsg <br /> ' Vinyl tubing (3/8-inch O D ) was extended from the sparging screen implant to the surface and a <br /> filter pack(fine glass beads)was installed around the screen implant from a depth of 20 to 25 feet <br /> bsg Bentonite sand(#8 bentonite)was used to make a 4-foot plug above the filter pack and the wells <br /> were grouted to surface grade with portland cement An eight-inch traffic box was installed at the <br /> surface for each IAS point <br /> SOIL VAPOR EXTRACTION - MASS OF RECOVERY <br /> ' Between 15 April and 19 September 2003, the ground water extraction and treatment system <br /> processed approximately 302,703 gallons of water The total volume of ground water treated as of <br /> 30 September 2003 is approximately 2,459,705 gallons <br /> ' GROUND WATER REMEDIATION <br /> Based on an EHD office meeting conducted on 05 April 2000 the EHD and the Central Valley <br /> ' Regional Water Quality Control Board (CVRWQCB) verbally agreed on the use of ground water <br /> extraction and treatment to mitigate the site As note above an SVEIIAS system has been installed <br /> and operated at the site to remediate hydrocarbon-impacted soil and ground water Over the course <br /> ' of the remediation, rising ground water elevation has submerged a significant portion of <br /> contaminated soil below the ground water table and capillary fringe Under this condition, <br /> hydrocarbon-impacted ground water has remained and the overall influence of the IAS system has <br /> ' demonstrated diminishing effectiveness at reduction of dissolved hydrocarbons Areas in the eastern <br /> portion of the site and at the northwest comer of the site have not demonstrated a sustained reduction <br /> of dissolved hydrocarbons Ground water has remained impacted <br /> m licati ns from th t March The i p oe se o f arc 2001 aquifer ground water extraction tests were the <br /> following The ground water table occurred within the screened interval of the well and the most <br /> likely source of the extracted ground water was from the highly permeable sand, encountered from <br /> 20 feet to 30 feet bsg <br /> ' Advanced GeoEnviranmentsl,Iac <br /> 1 <br />