SITE INFORMATION AND CORRESPONDENCE 1980-1999

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FACT SHEET, ATTACHMEP C • WASTE DISCHARGE REQUIREMENTS ORDER NO. 5-00- 6 CITY OF LODI WHITE SLOUGH WATER POLLUTION CONTROL PLANT SAN JOAQUIN COUNTY based partly on increased salinity of surface waters experienced by stakeholders during previous drought conditions. The impaired area is for the southern one-third of the Delta, upstream of the current discharge location. The Basin Plan objective for EC in the San Joaquin River at Jersey Point (downstream of the discharge location) strives for an EC of between 740 to 2,200 µmhos/cm depending on flow conditions of the river. This objective has been established to protect beneficial agricultural uses of the river. Review of Discharger self monitoring data from January 1998 through September 1999 indicates that the EC of the effluent ranged from 550 to 700 µmhos/cm and that the average EC measurement during periods of surface water discharge was 622 µmhos/cm. Based on this information no specific effluent limitation for EC will be required by this permit. However, this Order requires EC to be monitored in both the receiving waters and the effluent. This monitoring will allow for a better understanding of salinity trends of the receiving waters and what the impact of the discharge has on those waters. i) Trace constituents Federal regulations require effluent limitations for all pollutants that are or may be discharged at a level that will cause or have the reasonable potential to cause, or contribute to an in-stream excursion above a narrative or numerical water quality standard. Based on information submitted as • part of the application, in studies, and as directed by monitoring and reporting programs some constituents were regularly detected which were evaluated for the potential to exceed water quality criteria. Also, chlorine is used at the wastewater treatment plant as a disinfectant and, based on experience, has a reasonable potential to be discharged in toxic concentrations. Staff has used both Basin Plan numeric water quality objectives and EPA's ambient water quality criteria as a means of deriving a numeric limitation to protect the receiving stream from toxicity as required in the Basin Plan's narrative standard prohibiting the discharge of toxic constituents in toxic amounts. EPA developed the ambient criteria to protect aquatic life at considerable time and expense under public and scientific review. Constituents that have exceeded EPA's ambient water criteria in the effluent include cyanide, lead, mercury, zinc, and bis(2-ethylhexyl)phthalate (DEHP). Both cyanide and zinc have exceeded the Basin Plan numeric water quality objectives. Results are as follows: Wastewater Treatment Plant Effluent Sampling Results: Effluent Concentrations (µg/1) Sample Date CN Pb' Hg Zn' DEHP 12-11-92 --- 4.92 <0.2 110 130 01-31-93 --- --- --- 120 --- 02-19-93 <3.0 --- <0.2 --- --- 03-14-93 --- 1.3 <0.2 140 190 05-23-93 --- --- --- 160 --- 08-03-93 8.0 --- <0.2 --- --- 09-27-93 --- --- --- 50 <10 11-15-93 <3.0 1.0 <0.2 150 02-01-94 <3.0 1.5 <0.2 140 ---