NPDESwastewaterdischargepermits.ExistingStateregulationsundertheWaterQualityRegulationsof <br />Division41, section340-041-0120, setforthspecificparametersrelatedtowetweatherrelatedSSOs <br />whichestablishseasonalstormeventexceptionstotheSSOprohibition. EPAhasnotapproved these <br />exceptions. Consequently, theStateofOregonhaspubliclystatedthatitsposition willbeconsistentwith <br />theEPA’sstrictpolicyontheprohibitionofSSOsregardless oftheStateregulations, andthisisreflected <br />inthelanguageintheNDPESpermitheldbytheMWMC. <br />ThelackofexplicitrulesandguidanceforenforcementofwetweathercausedSSOsleavesOregon <br />NPDESpermittees (includingtheMWMC) atsomelevelofvulnerabilityindeterminingtheirlegal <br />liabilitiesfromthirdpartyenforcementactions. Itisclearthathaving arobustprogramformanagement <br />ofthesanitarysewersystemandI/Irelatedwetweather impacts, withmonitoring datatodocument <br />effectiveimplementation, isastrongelementfordemonstratinganaffirmativedefensetoanychallengeof <br />noncompliance. <br />SeveralotherelementsoftheCleanWater ActandtheNPDESprogramarepertinenttotheconsideration <br />ofaprogram tocontrolandreduceI/Ifromprivatelaterals. FederalregulationsundertheCleanWater <br />ActhavebeeninterpretedbytheU.S. EPAtorequirethatalltreatmentunitsofawastewatertreatment <br />facilitybeusedinthecollection, transport, andtreatmentofsewagewastes. Accordingly, bypassing any <br />treatmentunitisprohibited. ThisprohibitionisreflectedintheGeneralConditionsoftheNPDES permit <br />issuedtotheMWMC (ScheduleF, SectionB, paragraph3). However, manytreatmentfacilitieshave <br />beendesignedandareoperatedtoprotecttreatment unitsfromwashoutbypeakwetweather flowsby <br />intentionallydivertingsomeportionofthewastestreamaroundtreatment unitsandthen “blending” the <br />internalflowspriortodisinfectionanddischarge. Thispracticeprotectsthelong-termtreatment <br />capabilityofthewastewater treatmentfacilityandstillresultsinatreated, disinfectedeffluentthat <br />complieswiththewaterqualitystandards assignedintheNPDESpermit. Highpeakflowsgenerated <br />duringwetweathereventsaretheprimarydriverforutilizingblending, anyprogramthathelpstoreduce <br />thesepeakflowswillcontributetoareductionofthefrequencyandmagnitudeofablendingevent. <br />MWMC’sNPDESpermitalsocontainsaperformancerequirement thatisinfluencedbywetweather <br />derivedI/I, thatbeingarequiredminimumof85% percentremovalforboththe5-dayCarbonaceous <br />BiologicalOxygenDemand (CBOD) andTotalSuspendedSolids (TSS). Duringpeakflows, the5 <br />concentration ofpollutantsintheinfluentwastestreamarereduced bytheproportionofI/Iinthe <br />wastewater, whichdecreasestheefficiencyoftreatment andmakesitdifficulttomeetthe85% removal <br />minimum. Again, anyprogramthatreducesthevolumeofI/Iwillreducethedifficultyofmeetingthe <br />85% removalrequirement. <br />Projections aboutfutureregulationsrelatedtothemanagementandeffectsofwetweatherflows, andwhat <br />maybeincludedinfutureNPDESpermitsrelatedtowetweather/peakflowcontrols, SSOprohibition <br />language, sanitary sewerprogramrequirements, andblendingallowances ishighlyspeculative. Whatcan <br />beprojectedwithsomecertaintyisthatthefocusonSSOs, uncertainty abouttheregulatorystatusof <br />blending, therequirements forprograms toeffectivelymanagesanitarysewersystems, andthe <br />implicationsofperformancerequirementswillallcontinuetobeinplayandwilllikelydependupon <br />individualnegotiations forrenewalofanypermit. Correspondingly thequestionsofinterpretationof <br />NPDESrulesand regulationsandtherisksassociatedwithachallenge ofnoncompliance willcontinueto <br />beofconcerntopermittees. <br />ATTACHMENT 1 <br />Page3of10 Appendix C-62020 Eugene Wastewater Master Plan