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08,05,96 MON 16,41 FAA 510 842 6915 CPL HELP ti.U. 0003 DRAFT #2 BACKGROUND The area of the Highiet/Monterosso property addressed by this plan(the"project arca-) is located adjacent to West Byron Road. Pipelines, operated by CPL and other oil companies from approxiir€ately the early 1900s to the late 1950s, ran parallel to the northern edge of the Highiet/Monterosso property along West Byrom Road (Figure 2). These pipelines carried crude oil and Bunker C ail and were buried at a depth of approximately 3 feet below ground surface. Since 1988, soil and groundwater investigations Have been conducted at the 1-lighiet/Monterosso property on behalf of the Sunboro Development Corporation and CPL. The investigations have been reviewed by the SJCEHD. The results of these investigations indicate that limited amounts of petroleum hydrocarbons are present in subsurface soil along the northern edge of the property that fronts West Byron Road, apparently the result of releases from the pipelines. The petroleurrl hydrocarbons appear similar to those found at the Dividend property (APNs 238-02-10/13114), located northwest of the HighietlMonterosso parcel. The petroleum is likely degraded crude ail or Bunker C. The approximate locations of known petroleum-affected soil on the Highiet/Monterosso property are shown on Figure 2. The petroleum hydrocarbons have been reported to be present in soil in 4 of the 29 borings drilled at the site, at concentrations up to 1100 parts per million(ppm). The affected soil occurs between the depths of 5 and 15 feet; this vertical distribution is likely the result of fluctuating water table. The lateral distribution of petroleum hydrocarbons in soil is limited and does not appear to extend more than 50 feet southeast of the property boundary. The subsurface soil at the project area is predominantly silt and clay, with isolated sandy lenses, to a depth of at least 20 feet. The water table is about 7 feet below ground surface. Based on the groundwater investigations performed to date, shallow groundwater beneath the site has not been affected by the degraded crude oil. It has been determined by the SJCEHD that the degraded crude ail is not a threat to groundwater quality. It should be noted that shallow groundwater K%WPD0CS\C3499'SQLLXLAN DOC(WORD) 2