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• Construct storage ponds at west end of Bowers Field to detain flow from the new <br />east -west ditch and allow controlled release to Whiskev Creek. Size culverts at <br />the pond outlet to restrict outflow to Whiskey Creek and prevent any increase to <br />peak flooding downstream. <br />Construct storage ponds to the west of Whiskey Creek on Kittitas County property <br />upstream of Hungry Junction Road. Size ponds and outlet structures to attenuate <br />peak flow on Whiskey Creek and to work in conjunction with storage ponds west <br />of Bowers Field to avoid downstream flood impacts on Whiskey Creek. <br />The actions listed above are expected to alleviate flooding across runway 11-29 and <br />reduce shallow flooding on the western edge of the airport property. New and expanded <br />ditches route overland flow away from both airport facilities and downstream properties <br />between Whiskey and Mercer Creeks. The flood storage ponds provide enough <br />live storage to prevent routed flow from increasing peak flood depths downstream while <br />still draining within 12 hours of the flood peak to meet FAA requirements for surface <br />impoundment. <br />The complete technical memorandum from WSE is attached as EXHIBIT 1 for Board <br />review. Actual implementation of the storage proposal will entail significant additional <br />engineering and is expected to require additional funding. <br />FISCAL IMPACTS: <br />The cost of implementing the various preferred alternatives is currently being developed <br />Once costs are in hand, PW will approach the FAA requesting funding for constructing <br />the identified preferred alternatives. <br />ATTACHMENTS: <br />Exhibit 1: WSE Bowers Field EA Flood Reduction Alternatives Analysis <br />Page 2 of 3 <br />PUBLIC WORKS BOARD OF COUNTY COMMISSIONERS WORK SESSION STAFF REPORT <br />