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Peter MacNicholl February 24, 2003 Page 4 12. Page 7-1, Section 7.2.4. The text indicates that a number of extraction wells are not meeting performance standards in terms of capture zone extent. The text also states that until the production of all wells can be optimized, it will be difficult to determine the effectiveness of each extraction well. It would be helpful if the term optimized" was clearly identified (e.g. mass removal/unit groundwater volume, plume capture, cost/mass, etc.) The recommendations should include a list of wells that are not currently meeting the capture zone extent performance standard. The Report also needs to identify the specific steps that need to be accomplished to optimize production well operations. 13. Page 7-1, Section 7.2.4. It is unclear why EW015A is included in the recommendation for shut-down. LM146A has a significant increasing TCE trend, though still below the MCL. It's not clear if the thought is that by increasing EW018A, the groundwater flow at LM146A (600 feet away) is still expected to be toward EW018A. 14. Page 7-3, Section 7.5.5. 1 cannot concur with reducing sampling at LM063A mainly because there is no TCE time series plot provided for that well. Given the TCE time series plots for LM083A and LM146A, annual and twice per year sampling, respectively, appears appropriate. 15. Table 7.5-1, Concur with reduction in sampling frequency for: LM035AU, LM036A, LM083A, LM097AU, LM146A, LM168AU, 16. Table 7.5-1. The results for LM165A make me question if there was a change in sampling techniques or if the sampling depth (assuming micro-purge) was changed. I recommend maintaining sampling twice a year and re-measuring the sampling depth of the micro-purge inlet to ensure "proper" placement. If you have any questions regarding the comments in this memo, please call me at (916) 255-3717.