Laserfiche WebLink
Nitrite nitrogen)concentration in the river is slight when increasing the WQCF discharge from the <br /> current permitted discharge of 9.87 MGD(ADWF)to the proposed 27 MGD(ADWF). <br /> Data Availability: Manteca WQCF NPDES self-monitoring data from the San Joaquin River at Projected,median nitrite(as nitrogen)concentrations in the San Joaquin River are well below the <br /> R-1(just upstream of the WQCF discharge)corresponding to dry/below normal water years were Title 22 Primary MCL standard. <br /> used to calculate an estimated impact of WQCF effluent nitrite(as nitrogen)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 nitrite(as nitrogen)concentration and mass loading in <br /> discharge of 9.87 MGD(ADWF)and at proposed discharges of 17.5 MGD(ADWF)and 27 the San Joaquin River due to an increase in WQCF effluent discharged from the current <br /> MGD(ADWF). Improved WQCF treatment processes are projected to produce treated effluent permitted rate(9.87 MGD(ADWF))to the proposed rate(27 MGD(ADWF))is slight. A high <br /> having an average nitrite(as nitrogen)concentration of 1 mg/L. level of nitrogen removal will be accomplished through the activated sludge nitrification- <br /> denitrification process implemented as one of several treatment process improvements associated <br /> Results: The effect of an increase in WQCF discharge from 9.87 MGD(ADWF)to 27 MGD with the WQCF upgrade. Additionally,projected,median nitrite(as nitrogen)concentrations in <br /> (ADWF)is appropriately addressed in the receiving water at well-mixed conditions downstream the San Joaquin River are well below the Title 22 Primary MCL standard of 1 mg/L. <br /> of the discharge. During critical and dry/below normal San Joaquin River flow conditions,an <br /> increase in WQCF effluent discharge will slightly increase nitrite(as nitrogen)in the San Table 25: Estimated Impact of Nitrite(as Nitrogen)from WQCF Discharge in the San Joaquin <br /> Joaquin River,relative to its Title 22 Primary MCL criterion,downstream of the discharge as River at WQCF R-3 <br /> shown in Figure 19 and Table 25. The data set used in the present analysis included 83.3%non- <br /> detected data,therefore requiring the estimation of an ambient river concentration. The R-1 Nitrite as Nitrogen San Joaquin River Manteca WQCF Effluent <br /> ambient nitrite(as nitrogen)concentration employed in the present analysis was estimated by R-1 estimated concen.(mg/L)* 0.002 Flowrate(cfs) Flowrate(MGD ADWF) <br /> setting the ambient level at the method detection limit(MDL)associated with the City's non- Projected effluent concen.(mg/L) 1 600 1250 9.87 17.5 27 <br /> detected data. The MDL for nitrite(as nitrogen)from the City's NPDES self-monitoring data is Est.mass loading(lbs/day) 6 13 82.3 146 225 <br /> 0.002 mg/L. A slight increase in nitrite(as nitrogen)mass loading to the river is also projected. Est.downstream R-3 river concentration(mg/L)at 600 cfs 0.03 0.05 0.07 <br /> Est.downstream R-3 river concentration(mg/L)at 1250 cfs 1 0.01 0.02 0.03 <br /> Nitrite as Nitrogen *Statistic derived from the following data set: <br /> Data Period:January 2002—December 2002;Sample Size,n=12;Percent Detected Data=16.7% <br /> 1.2 <br /> J <br /> 1 SJR Flows <br /> 0.8 p 600 cfs <br /> 0.6 1250 cfs <br /> c 0.4 —WQO <br /> c 0.2 <br /> 0 <br /> U 0 <br /> 9.87 17.5 27 <br /> WQCF Effluent Flow Rate(MGD) <br /> Figure 19: Projected Change in San Joaquin River Nitrite(as Nitrogen)Concentration at WQCF R- <br /> 3 with increasing WQCF Effluent Flowrate <br /> Comparison to Water Ouality Objective: The California Code of Regulation,Title 22 <br /> Primary MCL criterion for nitrite(as nitrogen),incorporated into the Basin Plan by reference,is <br /> 1 mg/L. This Title 22 Primary MCL is the appropriate and most stringent water quality objective <br /> to apply to nitrite(as nitrogen)in the San Joaquin River. Estimated concentrations of nitrite(as <br /> nitrogen)in the San Joaquin River under critical and dry/below normal flow conditions show a <br /> slight increase,relative to the Title 22 Primary MCL,with an increase in WQCF effluent <br /> discharge from 9.87 MGD(ADWF)to 27 MGD(ADWF). The incremental change in nitrite(as <br /> City of Manteca Antidegradation Analysis 61 June 2007 City of Manteca Antidegradation Analysis 62 June 2007 <br />