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MWMC FACiLiTiES PLAN <br /> <br />of a future DO nttmericat limit may require future treatment facilities. However, for <br />purposes of this facility plan, no facility accommodations for DO are being considered. <br /> <br />Uercury <br />A TMDL for mercury is currently being developed for the Willamette River~ The <br />requirements resulting from the TMDL are tmcertain at this time. <br /> <br />Arsenic <br />The Willamette River was listed in the 2002 303(d) list for exceedances of the arsenic huJnan <br />health criterion for "water and fish ingestion." This 1/shng could eventually lead to <br />development of a TMDL for arsenic. Any numerical arsenic limit is unlikely to affect future <br />recommended treatment technologies at the WPCF and will likely be implemented as <br />source control reductions. <br /> <br />Cyanide <br />Cyanide discharges into the treatment facility are currently below the calculated maximum <br />headworks loading. Analytical laboratory results for final effluent indicate detectable levels of <br />total cyanide, while analysis of secondary effluent before chlorination has consistently <br />resulted in non-detectable amounts. The current disinfect/on process generates compounds <br />that analyze as cyan/de. These analytical results for total cyanide concentrations are not high <br />enough to cause an exceedance of a water quality standard in the Willamette River and wdll <br />not affect future recommended treatment technologies. <br /> <br />lVletals <br />Current effluent and biosotids metals concentrations are well below any regulatory <br />thresholds. Some changes to the Oregon criteria for metals are expected as a result of <br />triennial review. New criteria are expected to be adopted by the Envh:onmental Qual/ty <br />Commission (EQC) in April 2004, including metals criteria expressed as d/ssolved. This will <br />reduce the likelihood of water quality-based effluent limitations for metals becoming a <br />permit issue. Any numerical limits for metals are unlikely to affect future recommended <br />treatment technologies at the WPCF and wilt likely be implemented as source control <br />reductions. <br /> <br />Toxicity <br />There are no current problems complying with the acute and chronic toxicity requirements in <br />the permit. If a situation were to arise whereby effluent toxicity was identified as a potential <br />problem, a Toxicity Identification Process would be implemented that would likely result in a <br />source control reduction program. <br /> <br /> Phosphorus <br />Phosphorus has not been identified as an effluent quahty issue for the Willamette River and <br />there is currently no TMDL for phosphorus planned in the immediate future. However, <br />phosphorus is quickly becoming targeted for biological nutrient removal in the wastewater <br />treatment industry. FlexJbility for phosphorus removal should be considered when evaluating <br />alternative treatment technologies. <br /> <br /> 5-12 MWMC_5.0_REV8_VKS DOC <br /> <br /> <br />