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Copper The incremental change in dissolved copper concentration in the river is slight when increasing <br /> the WQCF discharge from the current permitted discharge of 9.87 MGD(ADWF)to the <br /> Data Availability: Manteca WQCF NPDES self-monitoring data from the San Joaquin River at proposed 27 MGD(ADWF). Projected,median dissolved copper concentrations in the San <br /> R-1(just upstream of the WQCF discharge)corresponding to dry/below normal water years were Joaquin River are below the Basin Plan objective. <br /> used to calculate an estimated impact of WQCF effluent dissolved copper in the San Joaquin <br /> River under critical(600 cfs)and dry/below normal(1250 cfs)river flows at a permitted Evaluation: The incremental change in dissolved copper concentration in the San Joaquin River <br /> discharge of 9.87 MGD(ADWF)and at proposed discharges of 17.5 MGD(ADWF)and 27 due to an increase in WQCF effluent discharged from the current permitted rate(9.87 MGD <br /> MGD(ADWF). Improved WQCF treatment processes are projected to produce treated effluent (ADWF))to the proposed rate(27 MGD(ADWF))is slight and below the magnitude of change <br /> having an average total copper concentration of 7µg/L. For the purpose of the current analysis, that could be reliably measured in the field. Similarly,the projected increase in dissolved copper <br /> and to be conservative,all copper present in WQCF treated effluent is assumed to be in the mass loading to the river is also slight. A significant level of copper removal will be <br /> dissolved form. accomplished through advanced wastewater treatment(filtration)implemented as one of several <br /> treatment process improvements associated with the WQCF upgrade. Historical removal <br /> Results: The effect of an increase in WQCF discharge from 9.87 MGD(ADWF)to 27 MGD efficiencies at similar advanced treatment plants are on the order of 25 percent(Nolte,2007). <br /> (ADWF)is appropriately addressed in the receiving water at well-mixed conditions downstream Considering 25 percent removal through filtration,mean and maximum effluent concentrations <br /> of the discharge. During critical and dry/below normal San Joaquin River flow conditions,an of 7µg/L and 10 pg/L are anticipated for copper. Additionally,projected,median dissolved <br /> increase in WQCF effluent discharge will slightly increase dissolved copper concentration in the copper concentrations in the San Joaquin River are substantially below the Basin Plan objective <br /> San Joaquin River,relative to its Basin Plan objective,downstream of the discharge as shown in of 10 gg/L. <br /> Figure 13 and Table 19. A slight increase in dissolved copper mass loading to the river is also <br /> projected. Table 19: Estimated Impact of Dissolved Copper from WQCF Discharge in the San Joaquin River <br /> at WQCF R3 <br /> Copper,Dissolved Copper,Dissolved San Joaquin River Manteca WQCF Effluent <br /> R-1 50t"%concen.(µg/L)* 1.91 Flowrate(cfs) Flowrate(MGD ADWF) <br /> 12 Projected effluent concen. /L 7t1I 600 1250 9.87 17.5 27 <br /> J 1 (jig/L) <br /> z 10 SJR Flows Est.mass loading(lbs/day) 11 22 0.6 1.0 1.6 <br /> c 8 0 600 cfs Est.downstream R-3 river concentration(µg/L)at 600 cfs 2.04 2.13 2.24 <br /> 0 <br /> 6 1250 cfs Est.downstream R-3 river concentration(µg/L)at 1250 cfs 1.97 2.02 2.07 <br /> 4- _WQ0 `5CP percentile statistic calculated using the following data set: <br /> CData Period:February 2002—December 2002;Sample Size,n=11;Percent Detected Data=91 <br /> 0 2 (1)The projected effluent concentration is provided as total copper;however,it is assumed that all copper present in WQCF treated <br /> 0 effluent exists in the dissolved form. <br /> 9.87 17.5 27 <br /> WQCF Effluent Flow Rate(MGD) <br /> Figure 13: Projected Change in San Joaquin River Dissolved Copper Concentration at WQCF R3 <br /> with increasing WQCF Effluent Flowrate <br /> Comparison to Water Ouality Objective: The CTR freshwater chronic objective calculated <br /> for dissolved copper in the San Joaquin River is 14.24µg/L when using a river hardness value of <br /> 172 mg/L measured during the low fall flows of October 2002 in the San Joaquin River at <br /> WQCF R-1. To that end,the more stringent Basin Plan dissolved copper objective of 10µg/L <br /> (Basin Plan,Table I11-1)is used for assessing the impact of increased WQCF discharge on <br /> dissolved copper levels in the San Joaquin River. Estimated concentrations of dissolved copper <br /> in the San Joaquin River under critical and dry/below normal flow conditions show a slight <br /> increase with an increase in WQCF discharge from 9.87 MGD(ADWF)to 27 MGD(ADWF). <br /> City of Manteca Antidegradation Analysis 49 June 2007 City of Manteca Antidegradation Analysis 50 June 2007 <br />