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bIARLEY COOLING TOWEI9ObIPANy • <br /> GROUNDWATER EXTRACTION AND TREATMENT SYSTEM 7 <br /> .SAN JOAQUIN COUNTY <br /> RESPONSE TO COMMENTS <br /> 30 January 2003 <br /> sampling frequency are considered the minimum necessary to adequa:ely assess <br /> compliance with requirements of the TO. <br /> 7. Comment: Monitoring and Reporting Program: We have been operating the <br /> groundwater extraction and treatment system and monitoring the groundwater and <br /> the influent to the treatment system for over 10 years. We believe the influent testing <br /> is no longer necessary and should be eliminated. The groundwater monitoring <br /> provides sufficient information of the influent water quality. We request that the <br /> requirement for influent monitoring be removed. We will monitor the :nr%ent as <br /> needed to investigate the rare occurrence ofa permit exceedance. <br /> Response: The only parameter that is sampled for influent groundwater quality <br /> under the existing NPDES permit No. CA0081787 is Total Dissolved Solids (TDS). <br /> Monitoring of the influent for parameters such as Total Chromium, Copper, Arsenic <br /> and TDS is required to get information on the concentrations of constituents in <br /> extracted groundwater and to assess the performance of the groundwater treatment <br /> system. In addition, the constituent concentrations in the influent in not always same <br /> as obtained from a groundwater monitoring well sample. Please see A—achment 1 for <br /> the revised sampling schedule for these parameters. <br /> 8. Comment: Monitoring and Reporting Program: Because we are pumping primarily <br /> groundwater, we do not think that analyzing the effluent for the general parameters, <br /> i.e. electrical conductivity, temperature, dissolved oxygen, chlorine (Cly, hardness, <br /> total suspended solids (TSS) and turbidity is necessary. Monitoring for these <br /> parameters provides no useful information to meeting the discharge requirements but <br /> adds substantial cost. TSS and turbidity are not an issue with groundwater at this site <br /> as the extensive monitoring has demonstrated over the many years of monitoring. C12 <br /> is not found in the groundwater and monitoring for C12 is unquestionably not <br /> necessary. Dissolved oxygen, hardness and temperature in groundwater are very <br /> uniform, as monitoring to date has amply demonstrated. We see no reason to <br /> continue to collect data that simply verifles the consistency of the groundwater <br /> quality and adds no value to the protection of the environment. <br /> Response: Monitoring for these parameters is essential for assessing compliance <br /> with Basin Plan objectives and receiving water limitations in the TO. As noted in the <br /> TO and Factsheet, chlorine residual has been reported in numerous effluent <br /> monitoring reports. To date, no explanation has been provided by MC-1- C regarding <br /> the source of chlorine in the final effluent. <br /> 9• Comment: Monitoring and Reporting Program: Quarterly sampling of the Stockton <br /> Diverting Canal is excessive based on the extensive testing of the Cana:over the past <br /> ten years. During the period of April I to October 1, the RWOCB stares that there is <br /> limited or no flow in the Canal-except for the RfcTC discharge. Consequently, the <br /> effluent monitoring of the MCTC discharge should be representative of tre water <br /> quality in the Canal. Secondly, monitoring the Canal once during the October 1 to <br />