WORK PLANS - Laserfiche WebLink

Home Browse Search

4. The capture zone maps (Figures 5.3-1 through 5.3-4, A-3 through A-16, and H-1 through H-12) do not show capture zones around all of the pumping wells. For example, Figure 5.3-1 shows a large capture zone around EW032AU which does not include EW010AU, EW012AU, EW035AU, EW004AU and EW034AU. In fact, the contours in groundwater mounding around EW034AU while the symbol (two short lines perpendicular to the contour pointing towards the center of the contour) indicates a depression. The Report does not discuss the anomalous mounding around EW034AU and tables in Appendix H do not indicate large fluctuations in pumping rate during the third quarter 1999 (extraction rate varied between 19 to 20 gpm) . In addition, the capture zone around EW011AU and EW037AU is rather large considering that only EW011AU was extracting groundwater (see also Specific Comment 13) . Please revise the capture zone figures to show consistent capture zones around pumping wells and correctly indicate which wells were pumping during the quarter to facilitate the evaluation process. 5. The Report suggests that certain percentages of contaminant plumes have been captured by the groundwater extraction system (e.g. , Section ES1.27, Page ES-4) . However, the Report does not provide the technical rationale for estimating the percent of plume capture. It appears that the capture percentage was based on a visual estimate of capture zone location and plume contours depicting concentrations above MCLs. It should be noted that the extraction system capture zones presented in the Report are estimated capture zones and are not based on actual data since there is an insufficient number of monitoring wells present around each extraction well to draw capture zones (especially in the above- upper horizon) . Therefore, a discussion regarding percent capture of contaminant plume(s) appears to be inappropriate. For clarity, please revise the Report to indicate how capture percentages were estimated. 6. The location of the infiltration gallery (IG1) , chimney drain (CD1) , percolation ponds and injection wells are not clearly depicted on Figure 5.2-1. For consistency, please revise Figure 5.2-1 to add arrows pointing to the location of the infiltration gallery (IG1) , chimney drain (CD1) , percolation ponds, injection wells and the northern and southern infiltration galleries. In addition, it would facilitate the evaluation process if the text of the Report included a verbal description of where the infiltration galleries, chimney drain, percolation ponds and injection wells are located (e.g. , to Section ES1.5, Page ES-2) and to add the location of the infiltration features to the groundwater contour maps. Therefore, please add a verbal description of where these features are located to the Report and add the location of all infiltration features to the groundwater contour maps. 2