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URMr. Jim Barton <br /> RWQCB <br /> July 26, 2012 <br /> Page 2 <br /> reading recorded on the boring logs. PID readings and visual observations will be used to <br /> select one or more soil samples from each boring. The remaining samples will be placed <br /> on hold at the analytical laboratory. When groundwater is encountered, the boring will <br /> be extended approximately five feet and a grab sample will be collected using <br /> hydropunch or similar technology. One deep boring will be drilled to a depth of <br /> approximately 60 feet bgs (BH-11) to assess the vertical extent of petroleum impacts <br /> reported during previous investigations in the area of boring B-7. Grab groundwater <br /> samples will be collected from approximately 20 feet (or first encountered groundwater), <br /> 40 feet, and 60 feet bgs at this location. A percussion hammer driven, Geoprobe® soil- <br /> coring system, will be used to collect both continuous soil cores for logging purposes and <br /> soil samples at discrete depths from each boring. After sampling is complete, all borings <br /> will be backfilled and sealed with neat cement grout and concrete patch material to restore <br /> surface to its original condition. Drilling, soil and groundwater sampling procedures are <br /> presented in Appendix A. <br /> Boring B-7 Area (Southwest Portion of the Site) <br /> Previous investigations conducted at Boring B-7 found total petroleum hydrocarbons as <br /> diesel (TPHd) in groundwater at 5,300,000 ug/L in August 2005. To further characterize <br /> the lateral and vertical extent of TPHd in the area surrounding Boring B-7, URS will drill <br /> five borings. <br /> One Deep Boring <br /> One deep boring will be advanced in the immediate vicinity of former boring B-7 to an <br /> approximate depth of 60 feet bgs. Groundwater grab samples will be collected from the <br /> approximate depths of 20 feet, 40 feet, and 60 feet bgs to assess the vertical extent of <br /> TPHd impacts previously reported at this location in 2005. Groundwater samples and <br /> one soil sample will be analyzed for total petroleum hydrocarbons as gasoline (TPHg), <br /> TPHd, and volatile organic compounds (VOCs). The groundwater sample collected from <br /> 20 feet bgs will also be analyzed for nitrate, sulfate, sulfide, manganese, iron, and TDS to <br /> aid in the evaluation of future remedial options for the Site, should that become <br /> necessary. <br /> Four Shallow Borings <br /> Four shallow borings will be advanced in the area surrounding Boring B-7 to characterize <br /> the lateral extent of impacts reported during the 2005 investigation. Borings will be <br /> drilled to first encountered groundwater or approximately 20 feet bgs, and groundwater <br /> grab samples will be collected from each boring. Groundwater samples and one soil <br /> sample from each boring will be analyzed for TPHg, TPHd, and VOCs. <br /> Boring B-14 Area (Southeast Portion of the Site) <br /> Three Shallow Borings <br /> Previous investigations conducted at Boring B-14 found TPHd in soil at 43,000 mg/kg in <br /> the sample collected from 15 feet bgs in August 2005. To further characterize the lateral <br />