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r y, S E C 0 R . Conceptual Site Model March 24, 2004 Page 15 In April of 2003, MW-2R and MW-3R were installed (offsite) to a total depth of approximately 30 feet =, bgs A SVE and sparge test was conducted in April 2003, vapors were extracted from wells VW-2S and VW-3S Air was injected into the bottom of VW-3D and then well VW-2D A tracer test was conducted in VW-3D suing helium for part of the test Based on the tracer test the radius of influence was approximately 46 feet Shaw's June 2003, Additional Assessment and Remedial " Feasibility Test Report, recommended SVE and air sparge as viable remedial alternatives, , groundwater extraction and treatment was ruled out as a viable alternative due to low flow rates (0 4 gallons per minute) observed during the feasibility test E; �a Excerpts from the Transmission Shop reports are presented in Appendix KF w� 6.5 Former Colombo/Toscana Bakery k � 6 5 1 Site Description The site is currently a Toscana Bakery located south of the intersection of West Charter Way and r� South Lincoln Street and directly south of the former Texaco station The site was a former Colombo/Toscana Bakery, utilized by the San Francisco Bread Company Historical records indicate that sub-surface facilities consisted of two USTs Two 4,000 gallon USTs were removed in February , 1994, these findings are summarized in SECOR's June 11, 1996 Summary Report, Site ; Investigation, Former San Francisco French Bread Company Facility Based on a review of p, • available documents during a file review conducted by SECOR, the date the USTs were installed could not be determined 6 5 2 Remedial Activities In February 1996 a 4-inch diameter vapor extraction well (VE-1) was advanced to a depth of 37 feet bgs The vapor extraction well was screened from approximately 15 feet bgs to 35 feet bgs Based on a review of available documents during a file review, operation of a soil vapor extraction system could not be determined 6 5 3 Historical Report Summary In February 1996, four borings were advanced (MW-1, VE-1, SB-1, and SB-2) Boring MW-1 was p converted into MW-1 and boring VE-1 was converted into a vapor extraction well During drilling soil samples were collected from the borings for lithologic description and chemical analysis The stratigraphy beneath the site and the surrounding area consists of predominantly a silt and clay r interval from the surface to approximately 44 feet bgs A sand-dominated interval underlies the site from 44 feet bgs to the maximum explored depth of 50 feet bgs TPHg was detected in soil at concentrations ranging from 3 mg/kg (SB-1-36) to 13,000 mg/kg (VE-1-21) Benzene was detected in w soil at concentrations ranging from 0 015 mg/kg (MW-1-16) to 44 mg/kg (VE-1-21) TPHg was t detected in groundwater at concentrations ranging from 160,000 pglL (MW-1) to 190,000 pg/L (SB- 2) Benzene was detected in groundwater at concentrations ranging from 22,000 pglL (MW-1) to 32,000 lag/L (SB-2) Groundwater gradients ranged from 0 045ft/ft to 0 003 ft/ft These findings are summarized in SECOR's June 11, 1996 Summary Report, Site Investigation, Former San Francisco French Bread Company Facility 11Chev(cn1920331REPORTSICSMICSM 92033(REV B)doc , ar