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December 15, 1987 Harding Lawson Associates <br /> 18040,001.03 <br /> Ms. Laurie Cotulla <br /> San Joaquin Local Health District ' <br /> Page 2 <br /> the ground-water level. The casing bottoms will be capped. The <br /> annular area between the casing and boring will be backfilled with <br /> No. 3 Monterey sand. A 6- to 12--inch layer of bentonite will be <br /> placed on top of the sand, and the remainer will be backfilled with <br /> a cement/bentonite slurry. The wells will be encased in a lockable <br /> well cover and protected by a metal watertight box. The wells will <br /> be developed by removing at least 3 well volumes from each well and <br /> we will monitor conductivity, temperature and ph before water <br /> sampling. <br /> Chemical tests will be performed on selected soil samples ob- <br /> tained during drilling operations and on a ground-water sample <br /> from each well. The soil will be tested for its concentration <br /> of total hydrocarbons. Water samples will be tested for their <br /> concentrations of benzene, tolulene, xylene and ethylbenzene. <br /> All materials removed from the borings will be placed in 55-gallon <br /> drums and stored on site. After the chemical test results are <br /> available, the disposition of the materials in the drums will be <br /> determined. <br /> Datum Exploration will perf orm the drilling operations and install <br /> the monitoring wells. They are licensed to install ground-water <br /> wells (License No. 48082) . <br /> We include with this letter a check for $35 for the cost of the well <br /> permit. We appreciate your help and cooperation in allowing us to <br /> provide a quick response to 7-Eleven Stores. <br /> Yours very truly, <br /> HARDING LAWSON ASSOCIATES <br /> 1'��L/z2� <br /> a� <br /> Stephen J. Osborne <br /> Civil Engineer <br /> SJO/sz <br /> 3 copies submitted <br /> Attachment <br /> ccs: 7-Eleven Store/Division 2299 <br /> Attention: Mr. David Lewis <br /> Mr. Don Gray, HLA/Novato <br />