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- <br /> WESTERN GEO-ENGINEERS <br /> Decontamination <br /> Prior to well installation, all sand packs will be subjected to a fresh <br /> water wash and sorted to avoid any contamination which might find its <br /> - way into the weils. Prior to installation, slotted casing or well <br /> screens will be steam cleaned. The hollow--stem augers will be steam <br /> cleaned between borings to eliminate cross-contamination. <br /> W-n11 Construction Log <br /> i In addition to the information included in the lithologic logs ]sept for <br /> t soil borings (i.e., grain size, visible contaminants, "sniffer" <br /> readings, color changes, groundwater elevation, thickness of individual <br /> units), a well construction log will be kept for the groundwater <br /> monitoring wells. It will include the diameter of the borehole, the <br /> size,, kind and depth of casing, the size,. kind and depth of"well "I <br /> screen or slotted casing, a grouting record (materials, intervals and <br /> placement methods), the size and interval of the gravel pack, the total <br /> ? depth of the well, type of the well, the date tested, static water <br /> level prior to the test, type of test pump or bailer, total time of the a <br /> of pumping/bailing, the rate of pumping/bailing and the final Nater <br /> level. <br /> Groundwater Measurement and Sampling <br /> ( Following development, the water level in the wells will be allowed to <br /> equilibrate for a minimum of 46 hours. Before groundwater level <br /> measurements are taken, each well will be surveyed from a reference <br /> - point to the top of the well casing. A graduated tape will be used <br /> with a conductivity probe to measure the depth to water or free product <br /> that may be floating on the surface of the water. This type of probe <br /> ` will enable accurate measurement of the free product-water interface. <br /> r if present, and will therefore indicate thickness of that floating <br /> product. As a standard practice, at least two measurements will be <br /> made. If two measurements of static water level made within a few <br /> minutes do not agree within 0.01 or 0.02 feet, measurements will be <br /> ' repeated until the reason f7r the lack of agreement is determined or <br /> until the results are shown to be reliable. <br /> Before sampling, the wells will be pumped or bailed to remove 5 casing <br /> volumes of water. Sampling of the groundwater beneath the free product <br /> layer and sampling the free product will then be accomplished by <br /> bailing the welll with a pre-cleaned bailer. Care will be taken to not <br /> contaminate the groundwater sample with surface water or free product. <br /> Water samples will be taken in trip_.';cate. Duplicate samples will be <br /> forwarded to the primary laboratory and the third sample will be <br /> analyzed by 4JEGE portable lab -(See Table 1 for types of analyses to be <br /> ----- — performed): — - — - <br /> 7 <br /> - 3 <br />