ARCHIVED REPORTS XR0003344 - Laserfiche WebLink

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Mr Michael Infurna, SJCEHD June 17,2005 Site Investigation Work Plan Palisades Station No 835, Stockton, CA Page 5 dated December 1, 2000, that this irrigation well be properly abandoned The status and pumping frequency of this well is currently unknown to Stratus personnel PROJECT APPROACH The proposed method of assessment (CPT technology) involves the use of an electronic piezocone advanced in one boring to provide a continuous log of the soil profile, while an adjacent boring, created by a direct push method, allows for collection of discrete soil and groundwater (Hydropunch) samples By continuously profiling the subsurface at multiple locations, soil conditions across the site may be correlated, and potential contaminant migration pathways identified, at the time of the investigation Soil and groundwater samples are subsequently collected, following a review of geological data, at strategic intervals pertinent to the goals of the investigation Based on the known distribution of dissolved MTBE, TBA, and TAME, and the request by SJCEHD in the April 8, 2005 letter, Stratus is proposing to further investigate the extent of petroleum hydocarbon impact immediately adjacent to the current UST area The locations of two CPT borings (CPT-1 and CPT-2) were selected to enable additional characterization of residual and dissolved petroleum hydrocarbon concentrations in this area (see Figure 2 and Figure 3 for locations) Two additional borings (CPT-3 and CPT-4) were selected to enable collection of additional data east and northeast (generally downgradient) of the UST complex Given the upgradient location of 7-11 facility #14117 relative to the site, and the relatively high TBA concentrations observed at well MW-7, Stratus is proposing to further investigate potential petroleum hydrocarbon impact near the western portion of the property Stratus is proposing to complete borings CPT-5 through CPT-7 at locations upgradient of pump island/UST locations at the site, and generally downgradient of the 7-11 facility, to further evaluate the possibility that petroleum hydrocarbon impact originating from an off-site source may be impacting the site Boring CPT-7 will be situated in the vicinity of existing wells MW-2 and MW-9 SCOPE OF WORK The objectives of the proposed work are to • Further characterize the lateral and vertical extent of petroleum hydrocarbon impact to soil and groundwater • Additionally characterize the geology beneath the site To accomplish these objectives, Stratus is proposing the following activities K IUSA Gasohnel0835\Work Planslpahsades835 workplan 06-17-05 doc 5TKATUO