SITE INFORMATION AND CORRESPONDENCE_2006-2007

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Mr. Mark Adams - 2 - 10 June 14, 2007 of ERD in both the upper and lower A Zone, the first round of samples have been collected to evaluate geochemical parameters for ERD, and continued monitoring including the geochemical parameters has been proposed in the Draft Plan. However, the Draft Plan only minimally makes reference to implementing ERD in the B Zone. 1. On page 3 of the Draft Plan it is stated, "A contingency provision for implementing ERD in the B zone if favorable geochemical conditions do not persist is presented as part of the Phase V IRA." The contingency plan for the B Zone is not detailed anywhere later in the document. A detailed plan for implementing ERD in the B Zone needs to be included in the revised Final Plan. Much stronger language is needed to clearly specify that the B Zone Plan is part of this Proposed Phase V Detailed Plan. 2. Per conference call discussions held on June 13, 2007, the Trust and the Regional Water Board have agreed to increased frequency of monitoring (to be discussed below) to better evaluate the need for implementing ERD in the B zone in a timely manner. A progress report (letter format) needs to be submitted to the Regional Water Board evaluating the semiannual progress and rate of natural attenuation in the B zone. We recommend this report be submitted after the baseline data and first two quarters of monitoring data have been collected, which would be approximately seven to eight months after the implementation of ERD begins. 3. We concur that natural degradation is occurring in the B Zone. However, our concern revolves around the current concentrations of PCE and the daughter products in the aquifer, the rate at which natural degradation is occurring, and how long that process will take to reduce all PCE to harmless end products. In December 2006, PCE was detected in MW-205B (beneath Bank of Stockton) and MW-207B (about 1000 feet down gradient of MW-205B) at 4,020 pg/L and 1 ,137 pg/L, respectively. These levels of PCE are two orders of magnitude too high to consider a plan that potentially allows natural degradation as the remedy for the B Zone in this area. 4. Finally, the implementation of a B Zone contingency plan is not included in the schedule. The possibility of implementing ERD in the B Zone after the semiannual evaluation needs to be schematically shown on the schedule. Proposed A and B Zone Groundwater Monitoring Program. Per conference call discussions held on June 13, 2007, Mark Adams representing the Trust, LFR, John Farr representing Lincoln Properties Limited (LPL), and the Regional Water Board have agreed to changes in the monitoring proposed in the Draft Plan. Those changes are reflected in the table included below. It is our understanding that this table will be included, as is, in the Draft and Final Plan.