SITE INFORMATION AND CORRESPONDENCE FILE 1

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v Geologicaf7eclmics Inc. `../ Page 2 Response to May 17,2000 Letter from SJC PHS/EHD Project No.723.2 June 1,2000 monitoring have been completed." You told me that the drilling process might account for transporting some contamination downward. You also acknowledged that your letter granted two additional groundwater monitoring events to account for this possibility. I stated that our purpose of accruing additional data before attempting off site vertical definition was to confirm the off site direction of plume migration prior to installing the more expensive deeper screened monitoring wells. We noted that including the following statement ending the same paragraph would give the impression that additional vertical definition was not planned "Several quarters of monitoring the deep monitoring well would be prudent to determine iiLfurther vertical investigation is warranted." GTI did not mean to imply that that if shallow off site groundwater was clean, then further work was not warranted. Clearly, the heavy contamination identified at depths of greater than 30 feet below grade (on site) will have a lateral groundwater migration component which requires off site investigation. Rather, the statement meant that if the contaminant concentrations diminished in well MW-101,then the bottom of the plume has been defined (on site). • Cone Penetration Technology (CPT)—In your February 16 and May 17, 2000 letters, PHS/EHD recommended the use of CPT with Simul-probe type sampling technology "to characterize the geology and also to better control against cross-contamination in sampling." I explained that during the advancement of deep borings MW-101 and SB- 201 heaving sands and incomplete core recovery were experienced at depths exceeding 75 feet bgs. These conditions were noted on the log borings previously submitted to PHS/EHD. In our work plan we stated that "Continued vertical exploration at the site will require the use of expensive drilling technologies, such as mud-rotary, due to the heaving sands." You reiterated PHS/EHD's position that CPT was appropriate for the site. On May 25, 2000, 1 called Mr. Noah Heller of BESST Inc. (Simul-Probe) and asked Mr. Heller for his opinion on the proposed use of CPT with Simul-Probe technology. Based on his extensive experience with Simul-Probe technology, various drilling methods, and the site information accumulated to date, Mr. Heller agreed with GTI's position that CPT with Simul-Probe technology would not be suitable for the site. He also agreed that utilizing Simul-Probe with mud rotary drilling would be the preferred method for obtaining discrete samples at the site. In addition, Mr. Heller volunteered to confer with PHS/EHD to discuss the matter in greater detail. In light of the above communications, GTI requests a re-evaluation of our April 11, 2000 work plan. As I outlined above, it is our intention to confirm the migration path of the groundwater plume, and then proceed if necessary with additional vertical definition on site utilizing mud rotary drilling. If it is still the position of PHS/EHD that CPT with Simul-Probe technology is warranted, then GTI respectfully requests the following actions of PHS/EHD: