EXH0681025072

Consultants is the Port of Seattle in the Kennedy/Jenks assisting (Port) preliminary design of a facility to augment flow in Des Moines Creek. A flowaugmentation facility would provide benefits to the aquatic ecosystem during summer periodsof stress caused by elevated temperature and lowflow. Potable water from Seattle Public Utilities(SPU) is currentlythe preferred source of water for creek flow augmentation. An active well, currentlyused for irrigationof the Tyee GolfCourse, may be an alternative water source. Discussionsof fights to the well water are underway, and the Port may not be granted the rightto water from the well. Chlorine levels in the potable supply prior to discharge creek. water will be reduced to the A dechlodnation system utilizing sodium sulfite tablets will be installed in a contact basin to be constructed near the creek. The dechlorinated water will be aerated prior to discharge tothe creek. The augmentation system will be controlledbased on downstream flow andtemperature conditions. This report introduces preliminary design concepts for a flow augmentation system includingsystem design, control and selection of dechlorinationagents. ! ! ! September 2000 1-1 006081.00AR 025076 Kennedy/Jenks Consultants FACILITY CONFIGURATION Figure1 illustratesthe proposedlocationandlayoutof theflow augmentationsystem.Aprocessflowdiagramis presentedin Figure2. A pipelinefor potablewater willbe connectedto anexistingwatermain(usedfor firesuppression)locatedat the endof the SouthSafetyZone of Runway34R. A dechlorinationbasinwill be constructedjustdownstreamof theconfluenceof the EastandWestbranchesof Des MoinesCreek. Sodiumsulfitetabletssuspendedina basketinthecontactbasinwillbe used ;for j dechlorination.A mechanicalaeratorlocatedneartheeffluentendof the contactbasinwillreplacedissolvedoxygen{DO) consumedby thedechlorinationagent. Effluentwillbe furtheraeratedas itflowsthrougha rock-linedchanneltotheoutfall. The riprap-filled , channelwillsupplementaerationwhileminimizingerosionof the creekbank.A monitoringstation,locatedat an existingdownstreamweir,willallowmeasurementof flow,temperature,and DO levels. A downstreammonitoringstationwillprovidefeedback I_ controlbasedon creekflowandtemperatureconditions.The systemwillbeprogrammedtomaintaincreekflowsat I cubicfeet persecond(cfs)atthe monitoringstation. A…

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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 [...]