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• ! A-2 monitoring wells commonly will be completed below grade and protected with a water-tight locking cover The top of casing (TOC) will be surveyed by a licensed surveyor, and all depths to water will be measured in relation to the surveyed mark on the TOC Monitoring Well Development Groundwater monitoring wells will be developed by surging, bailing, or pumping until clean, relatively sediment-free water is produced from the well The length of development time vanes, depending upon field conditions Development water is contained in 55-gallon barrels,which will be stored temporanly on site until disposal BOREHOLE DRILLING Boreholes are drilled by a licensed drilling subcontractor, using a truck-mounted drilling ng equipped with nominal 8-inch-diameter hollow-stem augers During drilling, soil samples for lithologic identification and possible laboratory analysis are collected every five feet in the borehole Boreholes are drilled to a predetermined depth below the ground surface or are terminated when two consecutive readings indicating hydrocarbons are not present in the soil are collected Borehole depths are based on site conditions, including but not limited to conditions such as depth to water, topography, and depth to bedrock To prevent cross contamination during drilling, all equipment is stearin cleaned prior to and between use at each borehole SOIL SAMPLING DURING DRILLING Soil samples will be collected during the drilling operations for three reasons (1) for field identification of the borehole lithology, (2) for qualitative field screening for the presence of contaminants, and(3) for chemical analysis For purposes of collecting soil samples for lithologic identification and for field screening, soil samples will be collected every five feet in the borehole The soil samples will be examined in the field and classified according the Unified Soil Classification system In addition to evaluating the borehole lithology, the soil samples will be screened in the field with a phototonization detector (PID) or similar instrument, and the relative permeability of the soil will be qualitatively estimated The lithology, PID reading, and estimated permeability of each sample will be recorded on the borehole log next to the depth interval from which the sample was obtained • Soil samples for laboratory chemical analysis will typically be collected at 5-foot intervals, at a minimum, to the groundwater table The samples will be obtained using a 2-inch-diameter by 18- Use or disclosure of data continued on this sheet is subject to the restriction specified at the beginning of this document MELIGEW2711WRKPLN DOC