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WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -21- WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0028 -22- CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS CITY OF MANTECA,CITY OF LATHROP AND DUTRA FARMS WASTEWATER QUALITY CONTROL FACILITY WASTEWATER QUALITY CONTROL FACILITY SAN JOAQUIN COUNTY SAN JOAQUIN COUNTY Therefore,this Order includes an effluent limitation for aluminum of 71ug/1 as a monthly 1800 ug/l. The maximum observed upstream receiving water MBAS concentration is less than average and 143 ug/1 as the daily maximum. 20 ug/l. An Effluent Limitation for MBAS is included in this Order based on of the Basin Plan water quality objectives for chemical constituents,floating material,and tastes and odors. 47. Iron: Iron concentrations in the effluent ranged from 170 ug/1 to 730 ug/1 while background concentrations in the San Joaquin River ranged from 780 ug/1 to 2800 ug/1 based on results from 51. Molybdenum: The recommended agricultural water quality goal for molybdenum,that would 12 samples collected between January 2002 and December 2002. The Basin Plan chemical implement the narrative"Chemical Constituent"objective,is 10 ug/1 based on Water Quality for constituent objective includes a receiving water objective in Table III-1 for iron of 300 ug/1 in Agriculture,Food and Agriculture Organization of the United Nations—Irrigation and Drainage the Delta,and the secondary MCL for iron of 300 ug/l. Both the receiving water and the effluent Paper No.29,Rev.1(R.S.Ayers and D.W.Westcot,Rome,1985). Molybdenum was not exceed the Basin Plan numeric objective and the secondary MCL. Therefore,effluent monitored in the effluent or in the receiving waters. Because of the uncertainty associated with limitations are included in this Order based on the Basin Plan chemical constituents objective. the lack of monitoring,additional studies of this constituent are warranted to more thoroughly evaluate reasonable potential for this constituent to exceed criteria. MRP No.R5-2004-0028 48. Manganese: Manganese concentrations in the effluent ranged from 13 ug/1 to 120 ug/1 while specifies monitoring for this pollutant. If the monitoring shows a reasonable potential to cause background concentrations in the San Joaquin River ranged from 82 ug/1 to 220 ug/1 based on or contribute to an exceedance of a water quality objective,this Order may be reopened to results from 11 samples collected between January 2002 and December 2002. The Basin Plan consider incorporation of appropriate effluent limitations. chemical constituent objective includes a receiving water objective in Table III-I for manganese of 50 ug/1 in the Delta,and the secondary MCL for manganese of 50 ug/1. Both the receiving 52. Carbofuran: Carbofuran was detected in the effluent and receiving water at concentrations water and the effluent exceed the Basin Plan numeric objective and the secondary MCL. greater than the OEHHA criterion of 1.7 ug/1. Because the data was greater than the method Therefore,effluent limitations are included in this Order based on the Basin Plan chemical detection limit but less than the laboratory's reporting limit,the data was flagged as"detected constituents objective. but not quantified". Additional monitoring is required. If the monitoring shows a reasonable potential to cause or contribute to an exceedance of a water quality objective,this Order may be 49. Chlorine: The Discharger currently uses chlorine for disinfection and has reported that it uses reopened to consider incorporation of appropriate effluent limitations. sodium hypochlorite for maintenance. Chlorine is extremely toxic to aquatic organisms. The Discharger uses a sulfur dioxide process to dechlorinate the effluent,but will discontinue this 53. Acute Bioassay: The new USEPA test procedure for acute bioassays(EPA-821-R-02-012,Fifth with the installation of the UV disinfection system. Because of the existing chlorine use and the Edition,October 2002)constitutes a more stringent acute toxicity limitation. The finding for future use of hypochlorite solutions without effluent dechlorination,there is reasonable potential ammonia indicated that there is a reasonable potential for the RWCF effluent to cause or for chlorine to be discharged at toxic concentrations. The Basin Plan contains a narrative contribute to an in-stream excursion above acute and chronic water quality standards for toxicity objective.Consistent with 40 CFR 122.44(d),it is appropriate to use the USEPA ammonia. To comply with the acute toxicity requirement of this Order and to comply with the ambient water quality criteria for chlorine for protection of freshwater aquatic life of 11 ug/1 as a Basin Plan narrative toxicity objective,the Discharger must reduce effluent ammonia 4-day average(chronic)concentration,and 19 ug/1 as a 1-hour average(acute)concentration to concentrations to comply with the new effluent limitations by 31 March 2004. Monitoring implement the narrative toxicity objective. Therefore,this Order includes water quality based Reporting Program No.R5-2004-0028 allows the bioassay to be modified to eliminate ammonia- effluent limitations for chlorine based on the USEPA ambient criteria to protect freshwater related toxicity until 31 March 2004,at which time the Discharger shall be required to aquatic life. implement the test without modifications to eliminate ammonia toxicity. The time schedule is authorized to be included in the Monitoring and Reporting Program based on 40 CFR§122.47. 50. Methylene blue active substances(MBAS): The effluent contains MBAS at levels that may cause or contribute to exceedances in the receiving waters of water quality objectives in the 54. Chronic Bioassay: The Discharger shall conduct the chronic toxicity testing specified in the Basin Plan. The Basin Plan includes the"Chemical Constituents"objective that incorporates Monitoring and Reporting Program. If the testing indicates that the discharge causes,has the state MCLS applicable to waters designated MUN. MUN is a designated beneficial use of the reasonable potential to cause,or contributes to an in-stream excursion above the water quality San Joaquin River. The Secondary MCL Consumer Acceptance Limit is 500 ug/1 for foaming objective for toxicity,the Discharger shall initiate a Toxicity Identification Evaluation(TIE)to agents(MBAS). The Basin Plan also includes water quality objectives that water not contain identify the causes of toxicity. Upon completion of the TIE,the Discharger shall submit a floating material or taste-or odor-producing substances in concentrations that causes nuisance or workplan to conduct a Toxicity Reduction Evaluation(TRE)and,after Regional Board adversely affect beneficial uses. The Basin Plan identifies non-contact water recreation,which evaluation,conduct the TRE. This Order will be reopened and a chronic toxicity limitation includes aesthetic enjoyment,as a beneficial use of the San Joaquin River. MBAS included and/or a limitation for the specific toxicant identified in the TRE included. concentrations in excess of the Secondary MCL-Consumer Acceptance Limit produce Additionally,if the State Board adopts a chronic toxicity water quality objective,this Order may aesthetically undesirable froth,taste,and odor. Foam has been observed on the surface of the be reopened and a limitation based on that objective included. discharge plume from the WQCF. The maximum observed effluent MBAS concentration is