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the adjacent Taco Bell facility to the southeast(SB-6). 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 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, collection of a grab groundwater sample at approximately fifteen feet bgs, and collection of a soil sample at the capillary fringe. K?,) ,1 ATC: Based on the September 1990 ExcelTech Site Plan obtained from SJCEHD (attached),ATC will re-locate proposed bp ring SB-4 to an area that approximates where QS-2 h � was collected. y!i Proposed Action 2 SJCEHD: ATC proposes to advance the boring (SB-5) to approximately forty feet bgs and collect a grab groundwater sample. 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 ATC-5, the EHD believes a monitoring well will better address the possible plume migration down gradient of the source area. { ATC: ATC will complete a groundwater monitoring well within proposed soil boring SB-5 (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 s SJCEHD: The EHD approves the advancement of SB-6 as described. iy ATC: Boring SB-6 will be completed as originally proposed. Monitoring Well Installation. Development, and Sampling ATC 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) 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 professional engineer or geologist, will log the boring and collect soil samples. During drilling, an approximately�1.5-inchh diameterborehole';will be advanced and logged, where applicable, to an approximate depth of 20 to 2.5 feet bgs. Soil samples will be collected just above the water table (i.e., at approximately 10 feet bgs)or where elevated PID readings indicate the presence of Additional Investigation Workplan Addendum Quik Slop No. 132,Stockton,CA . ., July 28,2009