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EPA COMMENTS <br /> DEFENSE DISTRIBUTION REGION WEST - TRACY, CALIFORNIA <br /> DRAFT CHEMICAL DATA ACQUISITION PLAN - WELL ABANDONMENT <br /> (MAY 94) <br /> General Comment <br /> 1. The Chemical Data Acquisition Plan (CDAP) is falls short of <br /> describing the actual abandonment procedures for Water <br /> Supply Well #4 . The CDAP does not refer to a well <br /> abandonment work plan. <br /> • The work plan providing abandonment procedures should be <br /> referenced within the introduction of the CDAP. Such a <br /> work plan will typically present well abandonment <br /> procedures, such as geophysical logging, grout placement, <br /> grout composition, and details of other work (similar to <br /> the Draft Final Well Abandonment Work Plan, May 1994) . <br /> Detailed Comments <br /> 2 . Section 3 .2 .2, page 6 <br /> Samples are to be collected using an "AMS liquid sampler. " <br /> • The plan should provide a description of this type of <br /> sampler, perhaps including a diagrammatic sketch, if this <br /> is not a sampler commonly used in the industry. The plan <br /> should clarify whether this sampler and the sampling <br /> method will provide samples with minimal disturbance for <br /> purposes of analyzing concentrations of volatile organic <br /> compounds. <br /> 3 . Sections 3 .4 .3 and 3 .4 .4, page 8, and Section 5 . 1 .1, page 10 <br /> These sections indicate that samples are to be collected at <br /> the midpoint of the second and fourth screened intervals, at <br /> 195 feet and 655 feet on Figure 3, and that one duplicate <br /> sample and one split sample are to be analyzed. However, <br /> EPA believes that samples from the uppermost screened <br /> interval in the Lower Tulare (the third screened interval in <br /> Figure 3) will more likely show the potential presence of <br /> contaminants than samples from the fourth screened interval, <br /> for the purpose of evaluating whether contaminants have <br /> migrated downward through the well. <br /> • The plan should be modified to collect a sample from the <br /> uppermost screened interval in the Lower Tulare (at a <br /> depth between 512 and 523 feet in Figure 3) , either in <br /> addition to the sample at 655 feet or instead of that <br /> deeper sample. Furthermore, the plan should state that <br /> epa/r929jm94 1 <br />