EXH0413022151

aquifer areas in the Des Moines Creek subbasins (determinedduringHSPF model calibration'), were included in the faun'econdition model forDes Moines Creek. Otherchangesforfutureconditionsmade inthehydrologicrouting'schemeincludedthe following: 1. SDW subbasin chang_ proposed in the west draining portion of the Third Rtmway project; 2. Additional flows from the North :EmployeeParking Lot (NEPL)and Cargo subbasins; 3, Overflows from theNorth Cargo and North Snow Melt Pump Stations;and 4, Elimination of SDN2,which drains to the IWS system. 2.6 PERIOD OF HYDROLOGIC RECORD Theanalysisoffurorehydrologicconditions(andcomparisontopre-developmentconditions) wasconductedusinganextendedhydrologicrecordrelativetotheperiodusedfortheHSPF modelcalibration.TheMillerCreekandWalkerCreekmodelwascalibratedusingahydrologic recordfromOctober1992throughAugust1996forreasonsdescribedinAppendixB. TheDes MoinesCreekmodelwas calibratedusinga hydrologicrecordfromJanuary.1994through September1996,asdescribedinAppendixB. Long-termrecordsarerecommendedforfloodfrequencyandflowdurationanalyses,typicallya minimumofI0years(-LI,S.DepartmentofInterior1982),Theperiodusedforevaluationof detentionfacilityrequirementsdescribedinthisappendixwas basedon therainfalland evaporationdatafromOctober1948thoughSeptember1996(a49-yearrecord). Long-termprecipitationandevaporationrecordsw_e usedasfollows: • HourlyprecipitationrecordsforSTIA'(NOA.AWeatherServicestation)fromOctober 1948 throughSeptember 1996;and • Daily pan evaporationdata (based on the Puyalhp Expcrimsnt Station) from October 1948throughSeptember 1996obtainedfrom King CountyDNR. 2.7 CALIBRATION OF AIRPORT FILL PARAMETERS A preliminary analysis was madeof the stormwatcrrunoffduring a 1-monthperiod (late January through late February 1999) at the 1998 embankment fill site to .calibrate HSPF PWATER parameter values. The Hydrocomp l:orecast and Analysis Model (HFAM) computer program was used for this analysis. This program incorporates the same numerical algorithms for hydrolo#c processes as HSPF, but has additional features that facilitate the study of surface r.no ,inter ow,andba ecomponents.E×e,l r. L--" .... 2ooo STIAMaster Plan Update Improvements A.15 .qy: _HERYt. ,: H,a_t¢.E 556-2912.001 (28) -- AR 022151 TableA-4. Summaryof emban"lonentfiHparametercalibration. PWATERParameter FillMaterialValue LESN 7.5 INFILT 0.02 INFEXP Z0 DEEPFR 0A0 BASETP 0.0 UZSN 0,28 AGWRC 0.90 INTFW 6,0 LZETP 0.6 IRC 0,t5 AGWETP 0.0 CEPSC o.lo NSUR 0.25 LSUR 300 SLSUR 0.07 Compared to till, the fill has the following characteristics: I. The fill…

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PSCAA Advisory Council Meeting Agenda
Add to CalendarMWednesday Mar 11, 9:00am - 11:35am
1904 3rd Avenue, Suite 105, Seattle, WA 98101
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 [...]