EXH0233018943

Subject: Comments on NPDES permit modification for Seattle-Tacoma International Airport Northwest Hydraulic Consultants has been retained on be_ffofthe Airport Communities Coalition (ACC) to provide technical reviews of stormwater, hydrology, and hydraulicsdements of proposed development actions at SeaTac airport. The purpose of this letter is to provideadditional comments on behalfofthe ACC for the proposed modification to NPDES PermitNo. WA-002465-1 for the Port of Seattle, Sea-Tac International Airport. The proposed modifications are those discussed by Ecology at a public hearing on February 12,2001. We have two comments. Both involve a need for clarity and consistency in stormwater standards discussed in the NPDES permit and those discussed in the airport's December 2000 Stormwater Management Plan (SMP). 1. Permit Condition SI.E (Page 11 of 53) and Condition SS.B (Page 24 of 53) include exemptions for untreated wastewater overflows "dueto stormwater flows in excess of the design criteria..." In thecontext ofCoadifion S 1.Ethese overflows are "authorizedbypassesR that are not subject to discharge limitations. In the comext of Conditions SS.B these overflows "willnot be considered abypass and will not constitute aviolation..." The problem with these conditions is that there is no clear or enforceable definition of stormwater flow designcriteriaincluded in the originalpermit or inthe proposed permit major modification.We recommend that the proposedmajormodification be republishedfor public comment after it is amended to include a summary of IWS system design criteria including the design criteria for stormwater flows which would (and would not) result in wastewater overflows from the IWS system into the storm drain system. Alternatively, it…

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 [...]