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V S"01 <br /> Mr. Michael Infurna 2 April 13, 2004 <br /> In September 2002, six direct-push soil borings were made adjacent to the former UST <br /> excavation and fuel piping system, and in the direction of groundwater flow. Analysis of the soil <br /> ,., samples detected TPH-D in one boring at a concentration of 2.7 ppm. No benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) constituents or methyl tertiary butyl ether(MTBE) were <br /> detected in any of the soil samples. <br /> Groundwater was encountered in the borings at depths ranging from 11 to 14 feet bsg. TPH-D <br /> was detected at concentrations ranging from 50 ppb to 390 ppb in three of the borings. No <br /> L• BTEX constituents or MTBE were detected in the samples. <br /> Shaw completed a site conceptual model (SCM) of the SBC site in April 2003. The SCM <br /> 'r indicates that numerous UST systems existed on nearby properties. The majority of these UST <br /> systems were located to the south, in the anticipated upgradient direction_ Several of these UST <br /> systems have reported leaks. Contaminants from some of these former UST systems may have <br /> "r impacted groundwater conditions at the SBC site. <br /> 60 In July 2003, Shaw installed three monitoring wells at the site, which are screened across the <br /> water table from 8 to 23 feet bsg. Soil samples were collected from at and just below the water <br /> table at depths of 10 and 15 feet bgs. No petroleum hydrocarbon analytes were detected in any of <br /> LA the soil samples. No analytes were detected in groundwater samples from the wells during two <br /> consecutive quarters. No field indications of fuel product or dissolved fuel constituents were <br /> observed during either sampling event. Copies of the well installation logs are included in <br /> LA Attachment 2. Well locations are depicted in Figure 2. <br /> Based on the lack of petroleum analytes detected in the monitoring well groundwater samples, <br /> r� the relative immobility of the remaining heavy-end petroleum hydrocarbons (if any) and the <br /> overall depth to groundwater, the site has been recommended for case closure, with no further <br /> action recommended. <br /> SCOPE OF WORK <br /> La The work plan addresses proposed procedures for destruction of monitoring wells MW-1, MW-2, <br /> and MW-3. Planned activities include over-drilling by hollow-stem auger and backfilling by <br /> concrete slurry. Prior to initiation of field activities, a site-specific health and safety plan will be <br /> developed to outline safety measures to be implemented during field activities. Underground <br /> Service Alert (USA) will be contacted and notified of anticipated drilling activities. Permits for <br /> destruction will be obtained from the SJCEHD. Methods and procedures used to complete field <br /> activities are presented below. <br /> o:SHAR>WSW4-0158.doc <br />