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contents. The PID reading will be noted on the log for the boring from which the sample was collected. Samples will be collected, placed in containers, preserved, and analyzed within the time constraints of applicable local, provincial, and federal procedures. Upon collection, each sample will be labeled with a unique sample identification number, sampler's initials, date, and time, listed on the chain of custody, and then placed in a cooler with ice. Custody of the samples will begin at the time of sample collection and maintained by the sampling team supervisor until samples are relinquished to the laboratory. Laboratory analyses will be performed by a California Department of Health Services -certified laboratory. 3.3.3 Boring Abandonment Following the completion of all sampling activities, each of the direct push sampling locations will be backfilled with cement containing up to five percent prehydrated bentonite. If groundwater is encountered, the cement -grout mixture will be tremied into the open boring. The tremie pipe will be placed approximately two feet above the bottom of the open boring until undiluted grout flows from the boring at the ground surface. If the tremie pipe must be raised during grouting, it will remain submerged at least 10 feet below the surface of the grout. Each of the borings will be marked with a traffic cone until the cement has set, and the surface restored to a reasonable facsimile of the surrounding surface area. 3.3.4 Groundwater Sampling Grab -groundwater samples will be collected by bailing a sample from within the drive casing, a driven stainless steel screen, or from a temporary casing and screen installed in a cased or open boring. The bailed sample will be immediately decanted to a container appropriate for the analysis to be performed, as shown in Table 2. Labeling and handling of the grab samples will be similar to the protocol used for soil samples. 3.4 GROUNDWATER MONITORING Three groundwater monitoring wells are used to characterize groundwater quality in the former UST area. Versar will collect samples from the wells to assess the present condition of groundwater. In the 2000 PA/SI, Versar recommended closure of the wells due to the minimal impact to this groundwater resource which is not used in the AASF area. Data from this groundwater sampling event will be used to further substantiate closure for this issue. Each monitoring well will be purged of approximately three casing volumes of water, the water level allowed to recover to at least 80 percent of the pre -purge level, and then the wells will be sampled. During purging activities, the pH, temperature, and conductivity of the purged water will be monitored and recorded at regular intervals to assess the influx of representative formation water into the well. Data collected prior to and during purging and sampling will be 9 3027 -03/ 104700.4766.230/JUL23' 03