EXH0412022134

GeoSyntec Consultants (OeoSyatec) has been retained on behalf of the Airport Communities Coalition (ACC) to provide a technical review of investigation, analysis and design relating to geotechnic.aland hydrogeological elements of the proposedThi_ Runway Expansion Projectat the Seattle Tacoma InternationalAirport. GeoSynteohas previously commented on seismic and geoteohnical aspects of the embankment fill and Mechanicatly StabilizedEarthWall. In my October2001 declarationin supportof ACC's motion for stay, I raised numerous concerns relating to the Port's Low Flow Analysis. This letterpresents an expansion on the issues raised in the declarationbased largely on review of theNovember 27, 2001 reportby Pacific GroundwaterGroup(PGG) titled "Port of Seattle - Sea-Tac Third Runway - Embankment Fill Modeling in Support of Low StreamilowAnalysis." Introduction Thepurposeofthelowflowanalysisistoevaluatetheimpactthatconstru_ionofthe ThirdRunway Embankmentwillhaveon therateatwhichrunoffand infiltration rechargethecreeks.Theimpactoftheembankmentisthatitstoresinfiltratingwater and subsequently releases it to rechargethe low streamflows at differenttimes thanif the embnnkment were not in place. To mitigate the impact of the embankment,excess watermustbe stored and released to the creeks to maintain conditions thatexisted prior to the construction of the embankment. The _na!ysis must be able to predict the magnitude of the impact of the embankmentand provide a sound basis for calculating I:_WR0380(SeaTa¢)_ubmittalV3eoSyatceSeaTae CommentLetter#3.doe AR 022134 e ) Walker/Terzi A GeoSyntecConsultants February2002 Page 2 the required storage to maintain flows in the creeks. Like my work of this type, the results of the analysesmustconsider the reliabilityof the analytical method and the uncertainty of the parameters input into the analyses, If the analyses are not conservative then other sources of water must be available to make up any shortcomings in the…

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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 [...]