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Fmr. Unocal - 2 - 4 October 2007 <br /> Fmr. Montgomery Wards <br /> 5400-5606 Pacific St., Stockton <br /> 2) The Workplan does not include labeled cross sectional views of the well construction <br /> and the lithological sequence to be monitored. Please submit two cross sections, a <br /> dimensionally labeled well detail, and a lithology of the monitored zone, with the revised <br /> Workplan. <br /> 3) The Workplan includes Attachment A, Field Methods and Procedures, which states that <br /> borings will be hand augered from surface to 8 feet bgs, and then drilled with an 8-inch <br /> diameter HSA to total depth. The Workplan Attachment A narrative varies from the <br /> Workplan text on page 2, which specifies using an air knife from surface to 8 feet bgs <br /> and a 6.5-inch HSA to the total depth of 40 feet. <br /> Note that the air knife or hand augering techniques are acceptable for starting the <br /> boring. However, the San Joaquin County Environmental Health Department and I <br /> recommend the use of at least an 8-inch diameter HSA for the remainder of the boring, <br /> due to the high potential for bridging of the filter pack or bentonite seal when 2-inch <br /> wells are constructed inside the smaller diameter (6.5-inch OD, 3.25-inch ID) HSA at <br /> depths greater than 25 feet bgs. Likewise, removing 40 feet of 6.5-inch HSA to <br /> construct the well in the open boring might result in a collapsed boring, which would <br /> necessitate re-drilling with a larger diameter auger. Please include the dimensions of <br /> the air knife, and specify in the text, the use of an 8-inch HSA (per Attachment A) in the <br /> revised Workplan. <br /> The revised Workplan is due 19 October 2007, with fieldwork to commence, with my written <br /> approval, no later than 5 November 2007. MW-15R will be sampled and results reported in <br /> the 4t' quarter 2007 monitoring report. Please provide at least 3 working days notice prior to <br /> fieldwork. You may call me at (916) 464-4615 for questions or additional information. <br /> JAMES L. L. BARTON, P.G. <br /> Engineering Geologist <br /> Attachment <br /> cc: Mr. Mark Owens, UST Cleanup Fund, SWRCB, Sacramento <br /> Mr. Mike Infurna, San Joaquin County Environmental Health Division, Stockton <br /> Ms. Jennifer Johnston, ENSR, 10411 Old Placerville Rd, Ste 210, Sacramento, CA <br /> 95827 <br /> Mr. J. Scott Seyfried, LFR Levine-Fricke, 4190 Douglas Blvd., Ste. 200, Granite Bay <br /> 95746 <br /> Ms. Nicole Gleason, Downey Brand Attorneys LLP, 555 Capitol Mall, 10`h Floor, <br /> Sacramento 95814 <br />