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Ms. Julie Raming - 3 - 26 April 2000 A 2. Groundwater recharge and groundwater mounding need to be monitored. The DIRP states that the extraction system and groundwater elevations will be monitored monthly for the first year, with operations reports submitted to Board staff annually. Although the DIRP does not state that the collected data will be reviewed and evaluated, it does suggest that if groundwater mounding is evident, monitoring wells BC-18 and BC-19 could be used as extraction wells to control the mounding. The final remediation plan should reflect monthly evaluations of the groundwater elevations, and propose threshold values that would trigger a need for additional extraction wells. During the first year of implementation, operations reports should be submitted to Board staff as part of the quarterly monitoring reports. 3. During our 18 April conversation, I also requested more detail on water quality sampling locations and schedules. Mr. Miller stated that the sampling details will be incorporated into the NPDES and WDR permits. Although the sampling details will be specified in the permits, this information needs to be outlined in the Final Plan as well. Groundwater Monitoring Reports The monitoring reports are concisely written and contain comprehensive tables of historical monitoring well data. I discussed the chloroform trends above in the DIRP section, and below I suggest a few format alterations that would make the reports more useful to me. 1. B&C should include a table of well screen intervals or geologic cross-sections illustrating the intervals. 2. The reports should include plots of chloroform concentration versus time, overlayed with groundwater elevations with time. The concentration plots B&C provided in the 11 September 1998 Groundwater Extraction report are excellent examples. 3. An enormous amount of groundwater elevation and concentration data is provided in the historical tables, including weekly data for 1985, monthly data from 1986=1988, and bimonthly data from 1989-1995. For the purposes of viewing long-term trends, I believe that B&C can enhance the table utility by reducing the amount of data presented to the semi-annual dates corresponding to the first and third quarters from 1985 to present. A footnote can direct the reader to the comprehensive tables in previous reports. 4. The detailed bimonthly data obtained between 1986 and 1995 should be condensed into a single concentration versus time plot with superimposed groundwater elevations illustrating the seasonal variability of the bimonthly data. 5. In the Groundwater Sample Collection Records, the units of Specific Conductivity should be identified. 6. In the 25 August 1999 report, Figure 2 incorrectly identifies 422 ug/1 chloroform in monitoring well BC-19. The correct value is 42 ug/l.