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the adjacent Taco Bell facility to the southeast(SB-6): tr1 ' ! 1 6�t The SJCEHD provided a technical response to the Workplan in+correspondence dated June 5, 2009, outlining the following comments. Included below is ATC's proposed action to address each,point: Proposed Action 1 I I 4 SJCEHD: The site map illustrating the proposed location for SB-4 does not include the approximate location where soil sample.QS-2 was collected. Based on information on file at the SJCEHD, the proposed location for SB-4 is not where soil sample QS-2 was collected,' ) therefore,you must provide technical justification for the proposed sampling point for SB-4, I collection of a grab groundwater sample at approximately fifteen feet bgs, and collection of a Gsoil sample at the capillary fringe. I ' I ATC: Based on 'the September 1990 ExcelTech Site Plan obtained from SJCEHD (attached),ATC will re-locate proposed boring SB-4 to an area that approximates where QS-2 l was collected. i 1 Proposed Action 2 SJCEHD: ATC proposes to advance the boring (SB-5) to approximately forty feet bgs and collect a grabgroundwatersample. instead of the proposed boring, the SJCEHD believes a monitoring well should be installed adjacent to soil boring ATC-5, and screened between approximately twenty and twenty-five feet bgs. Noting that MTBE was detected at 2,900 pg/L in a grab groundwater sample,collected at twenty feet bgs from AC-5, the EHD believes a } monitoring well will betteraddress the possible plume migration down gradient of the source area. ATC: ATC will complete a groundwater monitoring well within proposed soil boring SB-5 r� (proposed well MW-11). Additional discussion regarding methodology for installation, development, and sampling of the proposed groundwater monitoring well is outlined"below. Proposed Action 3 3 SJCEHD: The EHD approves the advancement of S6-6 as described. i r ATC Boring SB-6 will be completed as originally proposed. Monitorina'Well Installation, Development,and Sampling CATC will utilize hand-auger techniques to clear the proposed monitoring well location to approximately 5 feet bgs. All drilling and sampling activities will be performed consistent with ATC's standard operating. A soil boring will be drilled using a Combination Drill Rig which is equipped with 8-inch outer diameter(OD) , 1• hollow stem augers and direct push technology. Drilling will be conducted by a California C57-licensed drilling company. An ATC field. scientist, under the responsible charge of a California registered n professional engineer or geologist; Will log the boring and collect soil samples. LIt During drilling, an approximately 1.5-inch diameter borehole will be advanced and logged where applicable, to an approximate depth of 20 to 25 feet bgs. Soil samples will be collected just above the C . water table (i.e., at approximately 10 feet bgs)or where elevated PID readings indicate the presence of V- �i Additional Lrvestigation Workplan Addendum Quit Stap No 132,Stdcktoir,GA AWC J*28,2W9 :i