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Mr Ed Ralston <br /> Apni 16, 2001 <br /> Page 2 <br /> Soil samples were collected from beneath the removed dispensers and associated piping on April <br /> 8, 1999 During additional excavation activities unidentified fiberglass piping was encountered <br /> The piping was removed and soil samples were collected at the direction of Mr Michael hifurna <br /> of San Joaquin County Public Health Services, Environmental Health Division(SJCPHS/EHD) <br /> Additional excavation and sampling was completed on April 15, 1999 to remove the unidentified <br /> piping discovered on April 8, 1999 Over-excavation in the southern portion of the site was <br /> terminated to protect the structural integrity of the station canopy supports <br /> Following removal of the former station canopy, canopy footings and kiosk, additional over- <br /> excavation was completed on June 1 and 2, 1999 An additional 960 tons of soil were removed <br /> to a maximum depth of 31 feet bgs Over-excavation was terminated when the structural <br /> integrity of the sidewalk was endangered and groundwater was encountered <br /> Groundwater was encountered during additional over-excavation activities at a depth of <br /> approximately 31 feet bgs One water grab sample was collected from the excavation The grab <br /> water sample contained elevated TPH-g and benzene, toluene, ethylbenzene, and total xylenes <br /> (BTEX) concentrations <br /> Four groundwater monitoring welIs (MW-1 through MW-4) were installed on December 9 and <br /> 10, 1999 at the locations shown on Figure 2 The wells were screened from 5 feet above to 15 <br /> feet below the current water level Initial depth to water in MW-1 was 36 feet, therefore, the well <br /> was set at 50 feet bgs Groundwater rose to approximately 30 feet bgs after well completion <br /> Groundwater sampling events identified low intermittent concentrations of benzene and MtBE <br /> Four Geoprobe borings (GP-1 through GP-4) were completed on July 20 and 21, 2000 at the <br /> locations shown on Figure 2 The borings encountered petroleum hydrocarbon impacted soil and <br /> groundwater at depths of approximately 50 to 60 feet bgs Based upon the results of the <br /> investigation, IT recommended on-site soil sampling below 60 feet bgs for vertical delineation <br /> and installation of deeper level monitoring wells for assessment of groundwater impacts <br /> SCOPE OF WORK <br /> As stated previously, this investigation was performed to further evaluate the lateral and vertical <br /> extent of impacted soil and groundwater at the subject site The scope of work completed for this <br /> investigation included the installation of three on-site monitoring wells Monitoring well <br /> locations and installation depths were selected based upon data collected in previous <br /> investigations, an east to southeast groundwater gradient and a historical groundwater low of 70 <br /> feet bgs <br /> As required by the Occupational Health and Safety Administration (OSHA) Standard <br /> "Hazardous Waste Operations and Emergency Response"guidelines (29 CFR 1910 120), and by <br /> California Occupational Health and Safety Administration(Cal-OSHA) "Hazardous Waste <br /> Operations and Emergency Response" guidelines(CCR Title 8, Section 5192), IT prepared a <br /> Sate-Specific Health and Safety Plan (SSP) Prior to the commencement of fieldwork the SSP <br /> N lrancfp1\Projects\Projects191 1101 IN I A10102191 1011 rpt2 doc <br />