EXH1178045023

1500 First Interstate Bidg, 999 3rd Ave Seattle, WA 98104 and Earth Tech Inc. 10800 N.E.Sth St. Bellevue, WA 98004 June 19.2000 JE9907 AR 045024 Sea.Tac Runway Fil/ Hydrologic Studies Table of Contents ].0 EXECIYTWESUMMARY-- ] 1.] PROJECTBACKGROUND.................................................................................................................... } 1.]. l Proposed Cortr_'uctzon ............................................................................................................ 1.1.2 ProposedStormwmer ConrroL_...............................................................................................2 1_ PHYSIOGRAPHICFEATURESRELATEDTOHABITAT .......................................................................... 2 ;.2.. ,' Land b_e.................................................................................................................................. L2.2 SurfaceWater.........................................................................................................................3 L2.3 FLshHabitat............................................................................................................................3 1.3 HYDROGEOLOGICCHAKACTE.KIZATION............................................................................................ 4 1.3. l Geoioflc Umts ....................................................................................................................... 4 1.3.2 Currem Groundwaler Flow Condmona .................................................................................. 5 IMPACTASSESSMENTS...................................................................................................................... 5 ] 4.1 Fill Chemzstry. Effects ............................................................................................................. 5 1.4.2 Groundwater Recharge Effects ............................................................................................... 5 4.3 Fisherzes Effects ...................................................................................................................... 6 a Effects on the H.vdropertod m Local Wetlands ....................................................................... - 1.4.5 Effects on Wetland Area and Funcnons .................................................................................. 8 1.4.6 R_tc_,, of Wetland Mittgation Proposed ................................................................................. 8 1.4. 7 Shallow Groundwater and _'etiand Effects in Bo_ow AP_,as................................................. 9 1.._ P...EVI'EWOFSURFACEWATER MA.NAGEIVIL_"I"PROPOSALS................................................................ 9 1.5.1 Target Flow Regime Approach ............................................................................................... 9 1.5.2 Surface.Water Model (HSPF) Calibratwn ........................................................................... /0 1.5.3 Ftow Conn'ol Desagns ........................................................................................................... 10 1.5.4 Constructton Period ¢temporm3.,J impacts ............................................................................ 10 2.0 INTRODUCTION ............................................................................ 11 2.] SCOPE.Ab'THORIZATION,AND LIMITATIONS..................................................................................]l 2_ REPORT ORGANIZATION .................................................................................................................12 3.0 PROPOSED FILL AREA AND MILLER AND WALKER CREEKS ....................... 14 3.] PROPOSED CONSTRUCTION AND ENVIRONMENTAL PRECAUTIONS RELATED TO THE THIRD RUNWAY 3.1.1 Acqmsmon ofl'loraesand Farn_..........................................................................................1# 3.1.2 Embankment Filland Walls..................................................................................................14 3.1.3 Su_. "aceWater Management on and Near the Proposed F,mbankment ................................. 1.5 3. I. 4 _'etland and Creek Protections During Construction .......................................................... 1.5 3.2 CHAR.At.l _-_OF"THEHYDROLOGICENVIRONMENT................................................................... 115 3.2.1 Land Cover.. .. 16 3.2.2 Geoio_. ................................................................................................................................ 16 "_"_I Fill .......... . ........................ 17 3.22.2 Recent Deposits…

Open full document

Upcoming Events

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 [...]