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1997 Annual Report - 4 - 10 February 1998 Sharpe Facility 3) On page 6-5, Section 6.4.7 recognizes that Sharpe will be collecting flow rate data of individual North Balloon extraction wells. This activity needs to be expanded to all extraction wells to evaluate the operation of the entire remedial system, and to also provide input to the model. Monitoring of the treatment plant production rates, as proposed on page 6-4, Section 6.4.3 will not be sufficient to optimize capture zones. 4) Groundwater mounding occurred during all four quarters beneath the percolation ponds which suspected DNAPLs away from the site (page 2-4, Section 2.5.3.5). The discharges to the percolation ponds are likely driving suspected DNAPLs away from the site, causing increased concentrations of TCE observed in well MW456B, and exacerbating uncontrolled plume migration in the B zone of the North Balloon. The increasing trend seen in MW456B has been discussed in the 1995, 1996 and 1997 Annual Reports. The recommendation to continue to evaluate and monitor this trend is not going to rectify this condition and is an inadequate response to this situation. The Recommendations section of this report should be expanded to reflect Sharpe's commitment to the Comprehensive Water Master Plan (only briefly mentioned on page 6-5, section 6.4.10), with the goal to eliminate discharges to the percolation ponds and develop alternative disposal options. A specific time line for submitting this plan should be included. 5) Chromium was reported in monitoring well samples at concentrations exceeding baseline concentrations during 1997 (Page ES-4, Section ES 1.16 and page 4-15, Section 4.5.2.3). The recommendation in Section 4.5.2.1 proposes continued monitoring and evaluation to address this condition. The Post-ROD investigation, designed to locate the source of these increases should be discussed with a specific time schedule for 1998 activities should be presented in this Annual Report. 6) A statistically significant increase in the concentration of arsenic is occurring in monitoring wells at the facility Page ES-4, Section ES 1.17. Page 4-16, Section 4.5.2.4 states "arsenic concentrations from six A zone monitoring wells indicate a statistically significant increasing concentration". Arsenic is commonly a component in herbicides and or pesticides. Is it possible that Sharpe is using such pesticides at the facility? Please provide an explanation for these increases and actions Sharpe might take to reduce further degradation to the groundwater. 7) Review of the data shows incomplete definition of VOCs in both the North and South Balloon Areas. As stated on page 5-3, section 5.3.2.3 there is incomplete information along the southwest edge in the South Balloon A zone. Additionally, it is recognized from Figures 2.5-3 and 2.5-5, VOCs at depth are undefined in the C zone downgradient of wells MW451 and MW 445 (MW445C does not monitor the C zone sand). Increases in VOC concentrations in MW445B and MW445C further indicate the need for additional monitoring wells downgradient and off-site in this area. Similarly, no monitoring well exists in the C zone sand between wells MW413 and MW 505 located in the North Balloon. Well cluster MW527, proposed as a downgradient well to monitor North Balloon plume migration, should include a C zone well targeted at the sand zone at a depth of approximately 140-160 feet below ground surface to address this data gap.