SITE INFORMATION AND CORRESPONDENCE_1998-2000

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Y Mr. Mark Adams • - 2 - • 22 June 2000 The soil vapor cleanup goal in the Draft FS (150 µg/1 for PCE) is based on vapor transport leaching modeling that used the MCL as the groundwater cleanup goal. The soil vapor cleanup goal will need to be recalculated based on the SNARL for PCE. Additionally, as stated in the Basin Plan, soil cleanup levels should be equal to background concentrations of the individual leachable/mobile constituents, unless background levels are technologically or economically infeasible to achieve. The Draft FS states the SVES should clean up soil vapor to 150 µg/l within five years. Since LFR will revise this cleanup goal, LFR also needs to revise the estimated time schedule to achieve cleanup. The Lincoln Trust will need to periodically evaluate the technological and economical feasibility of maintaining the SVES, whether or not the soil cleanup goal is met. At a minimum, Lincoln Trust needs to include a formal evaluation of continued SVES operation in the five-year review reports. 3. Figures in the Draft FS showing the estimated extent of total hazardous substances in the A-Zone aquifer underestimate the western contaminant extent along West Benjamin Holt Drive by more than 3,000 feet (see Figure 50 in the Remedial Investigation Report, Lincoln Center dated 10 December 1999). As I stated in my Remedial Investigation Report review, additional long-term monitoring points are needed upgradient from the site in the A-Zone aquifer. Until such monitoring points are in place, data obtained by one-time, discrete groundwater samplings methods (i.e., Hydropunch® or equivalent) need to be included and/or considered by LFR when constructing contaminant concentration contour maps. LFR needs to revise the figures that underestimate the extent of contamination in the A-Zone aquifer(i.e., Figures 16, 31, 33, 34, 38, 40, and 42). LFR also needs to revise text in the Final FS describing the extent of contaminants in the A-Zone aquifer, where appropriate. 4. In several sections of the Draft FS, LFR discusses designating a non-attainment zone on the site. This Board does not have any such designation. LFR needs to remove any references to a "non-attainment zone" from the Final FS. SPECIFIC COMMENTS 1. (Section 1.6.51 LFR needs to revise this section to reflect currently available data. 2. {Page 27, Section 1.7.1 and Page 77, Section 4.3.3) The Draft FS states the GWETS [groundwater extraction and treatment system] Restart Report is scheduled for completion in March 2000. LFR needs to update this in the Final FS. 3. {Page 55, Section 3.3.7.11 The Draft FS states the cost for PCE removal is approximately$0.01 per 1,000 pounds of PCE removed. This appears to be an error.