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California R g oval Water Quality Coontrol Board <br /> Central Valley Region <br /> Robert Schneider,Chair (a <br /> Alan C.Lloyd Ph.D. Arnold Schwarzenegger <br /> Agency Secretary Sacramento Main Office Governor <br /> Internet Address: http://www.swrcb.c&gov/—mgcb5 <br /> 11020 Sun Center Drive,4200,Rancho Cordova,CA 956706114 <br /> Phone(916)464.3291•FAX(916)464-4780 <br /> 22 April 2005 OR 4, 6 7005 <br /> ENPERMIT/SERVIEESENT I h <br /> Cary Keaten Glenn Gebhardt <br /> City of Lathrop Califia LLC <br /> 16775 Howland Road 73 W. Stewart Road <br /> Lathrop, CA 95330 Lathrop, CA 95330 <br /> CONDITIONAL APPROVAL OF GROUNDWATER MONITORING WORKPLAN, CITY OF <br /> LATHROP,MBR WASTEWATER FACILITY,LATHROP, SAN JOA QUIN CO UNTY <br /> I have reviewed the 18 April 2005,Revised Monitoring Well Installation Workplan and Groundwater <br /> Sampling and Analysis Plan, prepared by Hydrofocus. The workplan was prepared in response to Waste <br /> Discharge Requirements (VDRs) Order No. R5-2005-0045, Provision G.l.c. Staff has the following <br /> comments on the workplan: <br /> 1. Please provide a more thorough description of the monitoring wells located on River Islands. <br /> According to the Workplan, of 22 wells only MW-1 through MW-12, MW-18, and MW-20 <br /> have been located and are accessible. All wells that are no longer needed or suitable for <br /> monitoring purposes must be located and properly destroyed. If the wells were surveyed, <br /> locating the wells should be relatively simple. <br /> 2. Please provide a complete inventory of all monitoring wells drilled at River Islands, Mossdale <br /> Village, Reiter Area, and the MBR facility. Do not include wells drilled for the Crossroads <br /> wastewater treatment system. The inventory shall list the wells, who drilled the wells, when <br /> they were drilled, the new name for the wells, and the disposition of the wells. Include <br /> proposed wells on the inventory. <br /> 3. Table 3 and Figures 6a, 6b, 6c, and 6d present the proposed monitoring wells, their purpose, <br /> and the locations of the wells. Review of the figures indicates a number of the wells intended <br /> to serve as background monitoring wells are located at the upgradient side of the land <br /> application areas. Specifically, staff are concerned about the location of the following: <br /> a. In Phase I land application areas,the following wells appear to not be placed in an <br /> optimum location: MWM-24, MWM-18,MWM-3, MBRMW-1, and MBRMW-2. <br /> b. In Phase II land application areas,the following wells appear to not be placed in an <br /> optimum location: MVR-34, MWR-30, MWR-28, and MWR-27. <br /> 4. Section C states that four-inch diameter wells will be placed in six or eight-inch diameter <br /> borings. Installation of four-inch diameter well casing requires a minimum 10-inch diameter <br /> hollow stem auger in order to allow adequate sand pack to be installed. <br /> 5. Section C describes the well construction and a well construction detail is included on <br /> Figure 7. When field conditions allow,please maximize the length of the annular seals <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />