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Mr. Alan M. Buehler <br />Central Valley Regional Water Quality Control Board <br />April 5, 2017 <br />Page 3 <br />Based on these findings, Amec Foster Wheeler proposes the advancement of four additional <br />hydropunch borings located downgradient of the borings installed in 2016 and four shallow <br />borings in an area with historically high relative TPHd soil concentrations. Boring location <br />rationale are as follows: <br />Hydropunch borings (DP-5 through DP-8) advanced southwest to northwest of DP-3 <br />and DP-4 as detailed on Figure 2 to attempt to further delineate the downgradient <br />TPHd concentrations in groundwater. These locations take into account the <br />groundwater flow at the Dopaco site north of the site <br />Shallow soil samples locations (DP-9 through DP-12) to be advanced near B-7, B-8, <br />B-24, and MW-5 (B-52). These boring will be located where TPHd concentrations in <br />soil were previously reported at the highest levels in deeper soil samples. <br />Field Investigation <br />Permitting and Utility Clearance <br />Prior to conducting the field activities, boring installation permits will be obtained from the San <br />Joaquin County Environmental Health Department (the County). <br />Underground Service Alert will be contacted to clear the boring locations of underground utilities <br />and a private utility location firm will clear the proposed boring locations using a combination of <br />radio frequency utility locating, ground penetrating radar, and magnetic and electro-magnetic <br />metal detecting equipment. Also, a private utility location firm will clear the proposed boring <br />locations using a combination of radio frequency utility locating, ground penetrating radar, and <br />magnetic and electro-magnetic metal detecting equipment. In addition, the boring locations will <br />be cleared by hand augering to 5 feet bgs prior to advancing the borings. <br />In addition, a project Health and Safety (H&S) Plan will be prepared prior to conducting the work <br />described in this Work Plan. The H&S plan will be produced in accordance with Title 8 of the <br />California Code of Regulations, Section 5192. <br />Borehole Advancement and Sample Collection <br />Under the supervision of a geologist, a C-57 licensed driller will advance direct push soil borings <br />equipped with 1-7/8-inch-diameter hollow drive rod to the desired depth to collect depth-discrete <br />soil or grab groundwater samples. Based on review of the existing data, Amec Foster Wheeler <br />will attempt to collect grab groundwater samples at depths of 25, 45, 55, and 65 feet bgs from <br />the proposed boring locations at DP-5 through DP-8. Upon reaching the desired depth, a clean, <br />stainless steel bailer will be used to collect the grab groundwater samples. The water will be <br />decanted into clean laboratory supplied containers and samples will be submitted to a certified <br />laboratory for analyses by TPHd by EPA Test Method 8015B. After the sample is collected at <br />the desired depth, the sampling assembly will be removed from the hole and decontaminated <br />using a high pressure washer and/or steam cleaner and a new drive point will be advanced to <br />collect a grab groundwater sample at the next indicated depth. Soils will not be logged from <br />these four borings (DP-5 through DP-8). <br />Amec Foster Wheeler