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Mr. Doug Stidham - 2 - 21 December 2000 <br /> • The agitation of dosed water into the filter pack provided by a Waterra pump is not likely to be <br /> adequate to effectively surge treated water into the filter pack and limits the disinfection to the <br /> saturated interval in the well. <br /> • The workplan failed to review the existing sampling procedures to determine if sources of <br /> contamination could be the result of sampling error rather than conditions in the wells. <br /> • The plans to prevent contamination of the wells during sampling events by using Clorox to <br /> disinfect well sampling equipment and the wellhead itself could result in routine additions of <br /> chlorine to the wells. Any well casing caps, water sounding equipment, or other equipment that <br /> is treated with Clorox must be thoroughly rinsed prior to opening the well cap or placing the <br /> equipment into the wells. <br /> The workplan as submitted is not approved. Before the follow-up sampling is performed, but no later <br /> than 26 December 2000, the Discharger shall submit a written addendum to the workplan addressing the <br /> items listed below. <br /> • Provide a complete description of the rinsing procedures that will be implemented to prevent <br /> introduction of chlorine into the wells <br /> • Describe the field instruments that will be used to determine if residual chlorine exists in the <br /> well. Include information on the manufacturer, model number, and detection limit for the target <br /> analyte. <br /> • To effectively disinfect a well, redevelopment of the well is often required. An evaluation of the <br /> need for redevelopment will be required if the test results show the disinfection was inadequate. <br /> • Review sampling procedures to evaluate the potential for contamination of samples during the <br /> sampling activities. <br /> In the future, your consultants must submit workplans at least 30 days prior to the proposed <br /> implementation date. If you have any questions on this workplan review, please telephone me at <br /> (916) 255-3116. <br /> �.. 7 <br /> TIMOTHY R. O'BRIEN <br /> Waste Discharge to Land Unit <br /> San Joaquin River Watershed <br /> cc: Mr. Mike Huggins, San Joaquin County Environmental Health Department, Stockton <br /> Mr. Raynold Kablanow, Ph.D., Geological Technics, Modesto <br /> CAPmjmc Film\Silm\FscalonlStidham 121900,DOC <br />