EXH2098033694

SUBJECT: Report of Discussionon 'SliceModel Integration' relating to "$ea-TacAirport Master Plan Update Low StreamflowAnalysis" Earth Tectt December2000 This is to documenta meetingI hadon April20, 2001 withPonyEllingsonandCrispinPrab_! of Pacific GroundwaterGroup(PGG)regardingmethodsof integratingresultsof the 'slice model' (PC-G,June 2000) overthe lengthof the proposed3rerunwayembankmentin orderto provide improvedestimatesof embankmentdrainage. Ponyhadindicatedearlierthatthe so- called 'slice model' actuallyconsistsof severalmodeling tools whicharelinkedtogetherto provide a cross-sectionalestimateof runwayembankmentdrainage.Themost importantof these models areknownas _Iydrus'and 'Slice'. In generalterms,Hydrusaccountsforvertical percolation of waterthroughtheembankmentandSlice divides thepercolatingwaterinto shallow and deep rechargecomponentsand accounts forhorizontaltransportof infiltrated groundwaterto its dischargeat the embankmenttoe. At ourmeeting on April20, Ponyrecommended thatPGGimprovethe existingdrainage estimate by rigorously integratingverticalinfiltrationover the embankmentfootprintusing Hydrusand performa more qualitativeassessmentof the horizontalSlicecomponent. Iagreed with Ponythathis recommendationwould improvethe accuracyof the existingembankment drainageestimateand would satisfyEcology's concernsregardingthe accuracyof the drainage estimatepresentedin "Sea-TacAirport Master Plan UpdateLow StreamflowAnalysis "(Earth Te¢l_iD_cember 2000). Theseconcernswere expressed in my memoto KevinFitzpatrickand A_:Kenny datedMatch9, 2001. - end - AR 033694 Exhibit-2098 EXH2098033694

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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]