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abandoned. Since this well is located in a spot which is important for monitoring, it was <br /> also recommended that LM3 be replaced. According to the conventions established at <br /> DDRW-Tracy, the new well should be labeled LM3A. Replacement of this well will be <br /> accomplished under a separate scope of work. <br /> 2.3.0.6. Redevelopment of the wells listed in Tables 1 and 2 was prioritized by <br /> evaluating which wells had the most severe turbidity problems. In addition, wells with <br /> sediment accumulations of greater than a few feet were recommended for redevelopment to <br /> remove the accumulated sediment and assure the continued performance of these wells. <br /> Wells which were not recommended for redevelopment or abandonment yielded low <br /> turbidity samples with careful purging. However, redevelopment of some of these wells <br /> may generally improve well performance and reduce total sampling time. Three lists of <br /> wells to be considered for potential redevelopment are shown in Table 3. The highest <br /> priority wells are listed under Options 2 and 3. Wells which may not require <br /> redevelopment to function adequately are listed under Option 4. <br /> 2.4 SOW ACTIVITY DESCRIPTION <br /> Montgomery Watson will utilize the existing Well Monitoring Program and Comprehensive <br /> RI/FS Work Plans and Standard Operating Procedures (SOPS) to perform the monitoring <br /> well redevelopment tasks. Redevelopment will be accomplished using the well <br /> development techniques described in the Comprehensive RI/FS Work Plan and RI/FS <br /> Work Plan Addendum. No modifications to the existing work plan are required beyond the <br /> information provided in this Work Plan Addendum. In addition, all work will be <br /> accomplished in accordance with the existing Site-Specific Safety and Health Plans found <br /> in the Well Monitoring Program and Comprehensive RI/FS Work Plans. The Safety and <br /> Health Plans will be amended as necessary if new hazards or changes in site conditions are <br /> observed. The following tasks will be accomplished as part of this Work Task. <br /> 2.4.1. SOW Activity A-12 - Redevelop 10 Monitoring Wells <br /> Montgomery Watson will review the original development records for the identified wells <br /> (Table 3) and for wells at DDRW-Tracy which have similar construction details but yield <br /> low turbidity samples to determine the redevelopment techniques that will be most likely to <br /> improve sample quality. Methods to be used in well redevelopment include swabbing, <br /> bailing, and/or pumping. The development water will be placed in purge tanks and emptied <br /> into the lined on-site industrial waste ponds. Upon approval of this Work Plan Addendum, <br /> well redevelopment will be performed. In order to maximize efficiency, redevelopment <br /> will be planned to coincide with development activities for new wells planned under the <br /> Comprehensive RI/FS. Once the redevelopment is completed, a report will be prepared <br /> and submitted covering all redevelopment under all Options exercised. This report will <br /> summarize field activities performed. If appropriate, additional recommendations regarding <br /> monitoring well abandonment or sampling procedures will be provided. <br /> -5- <br />