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Cary Keaten • - 2 - • 10 April 2007 result in only 10-inch diameter hollow stem auger rigs being acceptable at the site in future Addendums. Similarly, listing specific survey or engineering companies will limit ' who can perform the work. 3. In "Section B. Drilling Details," please address the following items: ' a. Supervision of Drilling and Well Installation - The need to submit and receive approval of a Groundwater Well Project Description Addendums (required by ' WDR Provision G.1.i.ii) is not described. Please add a description of the Addendum approval process. b. Drilling Equipment and Techniques - The Drilling Equipment and Techniques in ' Section B describes use of 10-inch diameter hollow stem auger to drill groundwater monitoring wells. Specification of the equipment will limit all wells to use of 10-inch diameter augers. You may wish to describe the drilling techniques I in more general terms so that 8-inch diameter augers or other drilling techniques are included in the Master Workplan. c. Drilling Equipment and Techniques - It is unclear why the boring depth is specified in the Master Workplan. Because groundwater conditions may vary considerably across the project area, the depth to groundwater and well construction details ' should be described in the Addendums. d. Decontamination Procedures - Despite the assumption that no hazardous ' materials are anticipated to be encountered, contamination of wells by bacteria or other waste constituents is an important issue that should be addressed. e. Soil Sampling and Borehole Logging —The description of the continuous core ' sampling device will require all borings to be continuously cored for lithologic sample collection. Continuous coring may not be necessary at every well site. Revise the workplan as needed. ' 4. In "Section C. Monitoring Well Design," please address the following items: a. As described above, statements that determine well construction details such as depth and screen interval are inappropriate in the Master Workplan. Please revise the text. ' b. The concept of constructing wells that are deeper than 24-feet by simply extending the screen interval is generally not acceptable. Wells should be constructed based on the location, seal requirements, and interval to be ' monitored. Please revise the text appropriately. c. Describing the sand pack as No. 3 sand should be avoided because conditions ' may not be the same throughout the project area. In addition, the sand pack should be surged prior to placement of the transition seal (bentonite) if conditions allow. ' d. Hydration of the bentonite transition seal is not described. Bentonite pellets should be hydrated prior to cement seal placement. e. The concrete described in the wellhead description is not included on Figure 4. In addition, a detail of a flush mounted wellhead is not presented in the Master Workplan. Please revise the figure. W lSuilWbnen'RSu]wquiALUArw WW'lNAH0.6MGOIXa¢nBMu D)d«