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California Wional Water Quality Contr&oard <br /> l`J Central Valley Region <br /> r Karl E.Longley,SeD,PE,Chair <br /> Linda AdamsArnold <br /> Secretaryfor Sacramento Main Office Schwarzenegger <br /> 11020 Sun Center Drive 8200,Rancho Cordova,California 95670-6114 <br /> Environmental Phone(916)464-3291 •FAX(916)464-4645 Governor <br /> Prolectlon htip://www.waterboards.ca.gov/centralvallcy <br /> RECEIVED <br /> 30 January 2007 JAN 312007 <br /> John Schroeter MAUD <br /> East Bay Municipal Utility District ReguletorYCompliance cnce <br /> 375 Eleventh Street <br /> Oakland, CA 94607-4240 <br /> CONDITIONAL APPROVAL, SOIL INVESTIGATION AND BACKGROUND MONITORING <br /> WELL INSTALLATION WORKPLAN, CAMANCHE DAM POWERHOUSE, CLEMENTS, <br /> SAN JOAQUIN COUNTY <br /> I have reviewed the 17 January 2007 Soil Investigation and Background Groundwater <br /> Monitoring Well Installation Workplan, prepared by Cambria Environmental Technology, Inc. <br /> The workplan describes installation of three wells and one additional soil boring to characterize <br /> soil and groundwater conditions at the proposed wastewater infiltration pond at Camanche <br /> Dam Powerhouse. We have determined that additional information is required; please <br /> address the following issues prior to proceeding with the project: <br /> I <br /> • The Workplan describes the groundwater flow direction as toward the Mokelumne River. <br /> This may be the case, but the information used to make the determination is not <br /> presented. Please describe how the groundwater flow direction was determined. <br /> • The drilling technique is described as air rotary. Because the Geology and Hydrogeology <br /> section of the report does not describe conditions that would require the use of an air <br /> rotary drill rig, please describe why that method was selected. If you determine that air <br /> rotary is required to drill the wells, then please update your Standard Operating <br /> Procedures (presented in Attachment B) to describe the.drilling technique and how <br /> samples will be collected. <br /> • The well casing bottom plug is not described; please use a threaded cap for the bottom of <br /> the well casing or secure a slip cap with stainless steel screws. Please submit a revised <br /> Figure 6 showing the change. <br /> • Unless dramatic groundwater elevation fluctuations are anticipated please limit the screen <br /> interval to a maximum of 20-feet. <br /> • The grouting of the soil boring that will be drilled at the location of the future wastewater <br /> pond is not described. Please describe how it will be grouted. It is considered especially <br /> important to effectively seal the boring since wastewater will be stored in an unlined pond <br /> above it. <br /> California Environmental Protection Agency <br /> Qd Recycled Paper <br />