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v Doug O'Neal March 19, 2002 Page 2 extent of the TCE plume and/or(2) ensure the monitoring system is in compliance with California Code of Regulations, title 22, article 6 at the time of post-closure permit renewal. DTSC (2002) identified the monitoring objectives that must be addressed south of the facility. • The timing of Workplan implementation is accelerated because of the close proximity of one of the proposed wells to a basin approved for treated water discharge. During the March 5, 2002 meeting, DTSC, CVRWQCB, and the facility agreed that installation, development, and initial sampling of the wells should be completed prior to discharge of treated water during prove-out of the modified groundwater treatment system- GSU anticipates that DTSC and CVRWQCB can provide comments to the facility on March 20 and that the facility can respond to comments in a letter by March 22. Implementation of the Workplan could then commence next week(March 25-29). GSU is available to observe drilling and well installation on March 27, 28, and 29. • GSU has the following comments that pertain to well design: Figure 10 (schematic well diagram) indicates that centralizers will be used. In GSU's experience, centralizers cannot be used for wells installed through hollow stem augers. The facility should clarify whether centralizers will be used and, if so, indicate the centralizer spacing that will be used. . The five feet of blank casing below the screened interval referenced in the text(Page 5) is not depicted in Figure 10 (schematic well diagram). The purpose of this blank casing interval is not provided. GSU recommends that this blank casing interval be removed from the well design. - The Workplan (Page 5) indicates that a drainhole will be provided inside the vault to minimize standing water. Based on the information provided, GSU is not certain that the drainhole will be effective because the vault will be encased in concrete. The facility should clarify how the drainhole will be effective. - The facility proposes to use Volclay grout as part of the annular seal. Volclay grout can be a brand name of grout as well as a type of grout. The facility should provide the specifications for the Volclay grout(brand name of bentonite product, water ratio, percent solids, etc.) that will be used in the wells. The Workplan (Page 4) states that if a sand lens is not encountered in the Upper Intermediate Zone, the borehole will be terminated at 135 feet below ground surface. As written, it is unclear whether a monitoring well will still be installed if a sand lens is not encountered. GSU recommends that a monitoring well still be installed with screened interval similar to well KI-12 (the actual screened interval should still be selected based on field observation). • The Workplan (Page 6) states that the new wells will be sampled as part of the next quarterly sampling event- As discussed with the CVRWQCB on March 19, 2002, the facility should sample the new wells shortly after installation and development(approximately the first week of April). Another factor that the facility may need to consider is that San Joaquin County has specific requirements regarding the timing of well development and sampling after well installation.