Laserfiche WebLink
August 30, 2000 <br /> Mr. Ed Ralston <br /> . Page 4 <br /> EPA Method 8260 in GP-3 at 9.6 parts per billion (ppb). MtBE was not reported in GP-4. <br /> TPH-g and benzene were reported in GP-2 at 128,000 ppb and 9,490 ppb, respectively. MtBE <br /> was not reported in GP-2. Groundwater analytical data is summarized in Table 2 and <br /> laboratory reports with chain of custody(COC} documentation are included in Attachment C. <br /> CONCLUSIONS <br /> Site assessment activities identified the following subsurface conditions: <br /> • Site soils consist of interbedded sands, silty sands, clayey silts a:1d sandy silts to the <br /> total depth explored. <br /> • The lateral and vertical extent of petroleum hydrocarbon impact to soil is generally <br /> undefined beyond a depth of 60 feet bgs. MtBE is absent in soil beyond 40 feet bgs. <br /> • The extent of groundwater impacts at 60 feet bgs have not been defined. MtBE is <br /> present along the southern site boundary. TPH-g and BTEX have not been defined <br /> downgradient of GP-2. <br /> • The downgradient extent of shallow groundwater impacts is defined by GP-4. <br /> RECOMMENDATIONS <br /> On behalf of Tosco, IT recommends additional delineation of deep soil and groundwater <br /> impacts. IT recommends onsite soil sampling below 60 feet bgs for vertical delineation and <br /> installation of deeper level monitoring wells for assessment of groundwater impacts. <br /> i <br /> N:lrancfp i 1Proj ects\Projects1911\01 111 A101021911011 rpt.doc <br />