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March 3, 1987 <br /> Harding Lawson Associates <br /> 18040,001.03 <br /> Ms. Laurie Cotulla <br /> San Joaquin Local Health District <br /> Page 2 <br /> Soil samples will be obtained approximately every 5 feet <br /> to the maximum depth explored. All samples will be <br /> sealed in brass tubes and the ends covered with aluminmum <br /> foil and caps taped over the foil. Samples will be <br /> placed immediately into an ice chest. The augers and <br /> sampling equipment will be steam cleaned prior to starting <br /> each boring; the sampling equipment will be washed in a <br /> solution of trisodium phosphate and tap water and rinsed <br /> in distilled water between samples. The soil samples <br /> obtained will be accompanied by a chain-of-custody form, <br /> which will be turned over to a chemical laboratory for <br /> testing.- <br /> We <br /> esting.We anticipate that the well will be 25 feet deep and will <br /> be constructed with 20 feet of screened section (0.02-inch <br /> by 2-inch slots) and 5 feet of solid PVC well casing <br /> (2-inch-diameter Schedule 40 PVC). The casing bottom <br /> will be capped. The annular area between the casing and <br /> boring will be backfilled with No. 3 Monterey sand. A <br /> 6- to 12-inch layer of bentonite will be placed on top of <br /> the sand, and the remainder will be backfilled with a <br /> cement/bentonite slurry. The well will be encased in a <br /> lockable well cover prior to water sampling and will be <br /> developed by removing at least three well volumes. <br /> Existing monitoring wells will again be purged and <br /> sampled. <br /> Chemical tests will be performed on selected soil samples <br /> obtained during drilling operations and on a ground-water <br /> sample from each well. The soil samples will be tested <br /> for their concentrations of total petroleum hydrocarbons <br /> (TPH) as gasoline. In addition to TPH, water samples <br /> will also be tested for benzene, toluene, and xylene <br /> (BTX). <br /> All materials removed from the boring 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 perform drilling operations and install the <br /> monitoring wells. They are licensed to install ground-water wells <br /> (License No. 48082) . <br />