EXH0410021884

ij I II iiii II i i I I i i i i i SEA-TACRUNWAYFILL HYDROLOGICSTUDIES REPORT == =, | I ,i I i iiim| i @ June 19, 2000 Pacific Groundwater Group Seattle, Washington • _, . _._,-,r AR 021884 ,mmmi ! 'e t Sea-Ta¢ Runway Fill Hydrologic Studies Report Preparedfor. WashingtonState Departmentof Ecology NorthwestRegloualoffice 3190 160_ AvenueSE Bellevue, WA 98008-5452 Preparedby:. Pacific GroundwaterGroup 2377 Ea_lakeAvenueEast Seattle,WA 98102 (206) 329-0141 wv_v.pg_vg.com Ecologyand Environment 1500FirstInterstateBldg,999 3rdAve Seattle,WA 98104 and Earth Tech Inc. 10800N.E.8thSt. Bellevue,WA 98004 June19, 2000 JE9907 -- --4Esm.. AR 021885 B Sea.TacRunwayFill HydrologicStudies TableofContents 1,0 EXECUTIVE SUMMARY.................................................. w ............ !J , l.l PROJECtBACKGROUND.............................................................................................................l j LI, I ProposedCons_c¢ion 2 1.1.2 ProposedStonrR_terCantrob................................................................................ 2 ],2 PHYS_3,R,_H]C]_-_TUR,ES-i_TED TO}'_TTAT ........................................................... 2 LZI /,andUse .....................................................................................................................2 1,2.2 Surface Water........................................................................................................ $ !,2.3 Fish Habitat............................................................................................................ I HYDROGEOLOGICQ-IARACTEP,/ZM'ION.......................................................................4 L3.1 GeologicD'nlta...........................................................................................................4 L3.2 CurrentC_ter FlowCanditions...................................................................... J ],4 IMPACTASSESSMENI_................................................ _...................................... $ 1.4.I Fill ChemistryEffects.........................................................................................................f L4.2 Grom_JwaterRechargeF,ffects........................................................................................J 1.4.3 Fbhexi_ £ffects.............................................................................................................. 6 1.4.4 EffectsontheH_/raperiod in Local Wedandx............................................................ 7 1,4.3 EffeCtSon g/etlm_,4reaot_ Functians............................................................................ J,4.6 Reviewaf VedandMitigationProposal......................................................................8 1.4.7 ShallowGroundwaterandl_etlandEffectsInBorrowAreas.............................................9 1.5-REVIEWOFSURFACEWATERMANAGEMENTPROPOSALS..............................................................9 1,5.1 TargetF/owRegimeApproach............................................................:.................... 9 L3.2 Sur]'_ce-WaferModel (HSPF)Calibralton.......................................................................10 1.53 FlawCan_,olD_lg_ .................,...................................:.........................................]0 1.3.4 Cons_uctionPerlod{temporary)Impacts...................._................................................I0 2.0 INTRODUCTION ................................................................. II 2.l SCOPE,AUTHOPJ_T1ON,PNI)LBa]TATIONS................................................................................! I 2,2 REPORTORGANIZgnON........................................................................................................... , 12 3.0 PROPOSED FILLAREA AND MILLER AND WALKER CREEKS ........................14 3.1 PROPOSEDCONSTRUC'fIONAND ENVIRO_AL PRECAUTIONSRELATEDTOTHETHIRDRUNWAY 3.1.1 AcqubitionofHomeJandF_ma................................................................................14 3.1.2 EmbanlonentFillandWalla.....................................................................................14 3.L3 SurfaceWaterManagementonandNearthePropose#Embanlonent...............................15 3.L4 WetlandandCreekProtectionsDuringCa_trucl/an..................................................1_ 3.2 CHARACTEROFTHEHY'DROLOGICE;NV]RONMENT....................................................................16 3,2.1 LandCowrr........................................................................................................... 16 3.2.2 Geology....:.........................................................................................................16 3.22.1Fill....................:..........................................................................................................I7 3.2.2.2 RccemDeposits.....................................................................................................17 3.2.2.3 Qvr......................................... :...................................................................... 17 3,2.2.4 Qvt............................................................................................................... lg 3.Z2.5 Qva................................................................................................................. 19 3.2.2.6 Qtb........................................................................................................................20 30.3.7 "Decp_GeologicUnhs........................................................................................................20 3.2,2.8 Comp_sontoPreviousGeologicbterp_emtions............................................................20 3.Z3 Sotl WaterBalance Campor_mx...............................................................................21 3.2.].! Wa_erSo_xes................................................................................................. 2] ' 3.2.3.2GroundwaterRechargeE_m=_s ........................................................................ 21 3.2.3.3 Comp_sonstoPrcvjo_Soi].Wate_Estimates...................................................................22 _.Z4 WaterC_rc_[otion..........................................................................................................22 _.2A,i…

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