EXH0236018956

Subject: Approval process for stormwatar management plan for proposed 3rd runway development actions at Seattle-Tacoma International Airport. NorthwestHydraulicConsultants(nhc)hasbeenretainedon behalfoftheAirportCommunitiesCoalitiontoprovide a technical review of stormwater facilities and related streamflow impacts from the proposed 3rd runway development at SeaTac airport. By a letter dated November 24, 1999, we provided our imdal comments from our technical review of documents describing the Stormwater Management Plan (SMP) for Master Plan Update Improvements at Seattle-Tacoma International Aurport. By a letter dated May 3, 2000, we provided follow-up comments resulting from our technical review of additional materials which were not available at the date of the initial review. The purpose of this letter is to remind you that the numerous substantial comments raised by us and by others have, to our knowledge, not yet been satisfactorily addressed, and to express concern over what has become a closed-doordesignreviewprocess. IndependenttechnicalreviewsbyotherexpertsundercontracttotheDepartmentofEcologyhaveconsistently corroboratedourconcerns.A linuted-scopereviewby PacificGroundwaterGroupIfoundserious"'fundamental questions"inthehydrologicmodelingwhich,ifleftuncorrected,wouldhaveledtotheconstructionoffacilities whichwouldbegenerallyundersizedand wouldnotachievetherequiredlevelsofflowcontrol.A broader-scope reviewbyKing Countyof"techmcar'issuesidentifiednumerousspecificproblemsbeforeevenconsideringthe mssucofhydrologicmodelcalibrationwhichseemstohavesincebecome themain focusofSMP revisions. A largenumberofsubstantiveissuesand concernshavebeenraisedwhichallneedtobeaddressedifthereistobe confidencem theSMP asadesigndocumentwhichwillaccomplishtheregulatorygoalsofflowcontroland environmentalprotection.Copiesofourpreviouscomment lettersareenclosedforreference.To ourknowledge, substantiallyallofourpreviouscomments remainunresolvedatthistime. The very limited mformation which has been disclosed from the King County review oftbe SMP indicates that King County has also raised numerous additional specific concerns which, to our knowledge, are also unresolved at this time. We refer in particular to an I i-page document with draft preliminary review comments dated 4/5/2000 which is in the files of both the Corps and Ecology and which was obtained by the ACC through public information disclosurerequests.Itshouldbcnotedthatthe4/5/2000documentdoesnotdealatallwithmodel calibration,which was firstralsedbyusasa majorconcernvlaemailtoconcernedpartieson 4/4/2000.We understandfrom verbal _Sea-Tac Runway Fill Hydrologic…

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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 [...]