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sites in order to determine the existence and magnitude of environmental contamination as well as appropriate remedial actions. Currently there are 99 existing and two abandoned monitoring wells and seven piezometers. A plume of ground water contaminated with tetrachloroethene (PCE) and trichloroethene (TCE) extends approximately 2,000 feet off DDRW-Tracy property and approximately 140 feet deep. DDRW-Tracy is conducting investigative and remedial activities in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Superfund Amendments and Reauthorization Act (SARA) to the extent practical. Currently DDRW-Tracy is conducting an RI/FS and initiating groundwater cleanup through an Interim Remedial Measure (IRM). As part of the environmental program, DDRW-Tracy has established an electronic environmental data base, data evaluation software, and is conducting a quarterly groundwater monitoring program. Delivery Order 0002 was awarded to Montgomery Watson, formerly James M. Montgomery, Consulting Engineers, Inc. (JMM), to conduct sampling under the Well Monitoring Program and Options 2, 3, and 4 have been activated to cover redevelopment activities for up to 43 monitoring wells which have historically yielded samples with high turbidity values or have accumulated sediment within the well casing. 2.3.0.2. Based on data collected during quarterly groundwater monitoring at DDRW- Tracy, it was determined that wells LM1 through LM43 were frequently yielding samples of relatively high turbidity and high concentrations of total metals. During the September 1992 round of well monitoring, a turbidity evaluation was conducted to assess the possible effects of high turbidity on analytical results. Wells LM15, LM16, LM25, LM26, and LM32 were sampled using both a bladder pump and a bailer to compare analytical results for samples obtained by each method. The bailed samples were significantly more turbid than the pumped samples. Based on the analytical results from the turbidity evaluation, it was determined that concentrations of total metals were much greater in the more turbid samples. All of the remaining wells from LMl through LM43 that were sampled during the September 1992 round (those wells not included in the turbidity evaluation) were sampled using a bladder pump. While sampling all wells, data was collected from purging activities to determine how turbidity was affected by the volume purged. A comparison of measured well depths to constructed well depths was also made to determine if sediment was accumulating within the well casings. 2.3.0.3. Samples with a turbidity of less than 5 nephelometric turbidity units (NTU) could not be obtained from 13 wells. In addition, seven wells were identified which required purging more than 10 well volumes to obtain a sample with less than 5 NTU. It was recommended that these wells be given highest priority for redevelopment. these wells are listed in Table 1. 2.3.0.4. Table 2 lists all wells not already shown in Table 1 which had calculated sediment accumulations of more than one foot in the bottom of the casing. These wells required careful purging to achieve sample turbidities of less than 5 NTU. 2.3.0.5. Extensive purging was performed at well LM3, but low turbidity samples still could not be obtained. Based on observations made during field sampling, including the volume of water purged and the methods used, it was recommended that well LM3 be -2-