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California Regional Water Quality Control Board ' <br /> Central valley Region °' l' <br /> Robert Schneider,Chair <br /> Winston H.Hickox Gray Davis <br /> Secretaryfor Sacramento Main Office Governor <br /> Environmental Internet Address: http://www.swrcb.ca.gov/--rwgcb5 <br /> Protection 3443 Routier Road,Suite A,Sacramento,California 95827-3003 <br /> Phone(916)255-3000•FAX(916)255-3015 <br /> 29 November 2001 <br /> Mr. Doug Stidham, City Engineer <br /> City of Escalon <br /> 1854 Main Street <br /> Escalon, CA' 95320 <br /> CONDITIONAL APPROVAL OF GROUNDWATER MONITORING WORKPLAN, CITY OF <br /> ESCALON WASTEWATER TREATMENT PLANT, SAN JOA QUIN COUNTY <br /> I have reviewed the "Workplan, Monitoring Well Installation, City of Escalon Waste Water Treatment <br /> Plant, "prepared by Geological Technics, Inc., dated 17 October 2001. The plan was prepared in <br /> response to Regional Board correspondence dated 23 August 2001 requesting the City of Escalon to <br /> either proceed with the groundwater data analysis using interwell comparison of analytical data or <br /> submit a groundwater monitoring well workplan for installation of upgradient wells. The City has <br /> determined that installation of additional groundwater monitoring wells is preferable. After reviewing <br /> the workplan, I have the following comments: <br /> • Abandonment of Well MW-2R is not required. The City can propose a monitoring network that <br /> does not include Well MW-2R except as a groundwater elevation measuring point. <br /> • If the abandonment of Well MW-2R is pursued, the pressure grout method of well destruction is <br /> approved only if: a) the San Joaquin County Environmental Health Department (SJCEHD) issues <br /> a permit for pressure grout destruction of the well, and b) the work is performed in accordance <br /> with the requirements of the SJCEHD Well Standards Section 13.17 and the California Well <br /> Standards, Bulletin 74-90, Section 19C4, which requires sealing pressure to be maintained long <br /> enough for the sealing materials to be properly set. <br /> • The proposed two-week well disinfection interval is excessive. California Water Well Standards <br /> Bulletin 74-81 Appendix C recommends a 24-hour interval prior to pumping the well. The <br /> SJCEHD Well Standards Section 8.2 similarly recommends 24-hours of disinfection. You shall <br /> limit the time the disinfection solution exists in the wells to a maximum of 48-hours, or describe <br /> how leaving the solution in the wells for the proposed time will not result in plumes of <br /> trihalomethanes emanating from each of the wells. <br /> • Section 13.10.8 of the SJCEHD Well Standards recommends surging the filter pack prior to <br /> installation of the transition seal. If borehole conditions allow, please perform that task. <br /> • Groundwater monitoring shall be performed as described in the Groundwater and Surface Water <br /> Monitoring Workplan and the Monitoring and Reporting Program Order No. 5-00-142. In <br /> California Environmental Protection Agency <br /> �d Recycled Paper <br /> The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. <br /> For a list of simple ways you can reduce demand and cut your energy costs,see our Web-site at http://www.swreb.ca.gov/rwgcb5 <br />