TagMiller Creek(260)

Draft Declaration of Restrictive Covenants by Port Of Seattle for four mitigation sites associated with Seattle-Tacoma International Airport Master Plan Improvements, including third runway construction. Covers Miller Creek Buffer Areas, Miller Creek/Lora Lake Wetland and Floodplain, Tyee Valley Golf Course Wetland Enhancement, and Auburn Wetland Mitigation Site (approximately 69 acres in City of Auburn). Executed

This document contains hydrological flow data for Miller Creek, including a ranked frequency analysis of the lowest monthly mean streamflows recorded between August and May from 1948 to 1995, alongside modeled daily and hourly stream flow outputs from 2-year/72-hour and 2-year/2-hour storm events simulated in August 1996. The analysis identifies a 5-year mean low flow of approximately 0.60 cubic feet per second for the lowest month in the August–May period. Acute and chronic water quality standards are also evaluated in relation to effluent and receiving water flows during the storm event.

This technical document from a March 25 meeting discusses stormwater mixing zone analysis for proposed outfalls around Seattle-Tacoma International Airport (STIA). Because standard stream flow conditions (7Q10 and 30Q5) are extremely unlikely to coincide with stormwater discharge events, Parametrix proposed a site-specific approach using higher-probability rainfall-based discharge combinations instead. The analysis found that reasonable dilution of 14- to 24-fold could occur within about 15 to 20 meters downstream, though complete mixing requirements would exceed standard regulatory width and flow percentage criteria, prompting a request for exceptions under WAC 173-201A-100.

This technical document describes a mixing zone analysis for stormwater discharge from the 3rd Runway North at Sea-Tac Airport into Miller Creek, designated as Basin SDW-1. The analysis uses design storm modeling with various rainfall scenarios (2-year/2-hour, 2-year/72-hour, and 3-year/72-hour events) to calculate effluent flow rates for both acute and chronic water quality criteria. Stormwater from the basin's approximately 128 acres of pervious and impervious area is routed through a detention pond before discharge, with outflow rates determined by a storage-discharge rating curve.

This document is a fact sheet accompanying an NPDES (National Pollutant Discharge Elimination System) permit issued to the Port of Seattle for Seattle-Tacoma International Airport, governing how the airport manages and discharges treated industrial wastewater and stormwater. It covers discharge locations into Puget Sound, Des Moines Creek, Miller Creek, and the City of SeaTac storm sewer system, and establishes effluent limitations and monitoring requirements. The permit addresses water quality standards, pollution prevention plans, and compliance schedules to protect surrounding waterways from airport-related contaminants.

Draft map AR035006 showing restrictive covenants on the west side of Seattle-Tacoma International Airport (northern section). Features include Relocated Miller Creek, Lora Lake, Miller Creek/Lora Lake/Vacca Farm Wetland and Floodplain Mitigation Area, Miller Creek Mitigation Area, Toe of Fill boundaries, Relocated S. 154th Place, and multiple 60-foot ROW designations (30 feet each side from center

Attachment G table detailing wetland acreage impacts and mitigation credits by wetland function for in-basin and Auburn sites, related to the Sea-Tac Airport or associated project. Functions covered include Resident/Anadromous Fish (8.6 acres impacted), Passerine Birds (14.9 acres), Waterfowl (1.9 acres), Amphibians (9.8 acres), Small Mammals (13.2 acres), Exports Organic Matter (10.9 acres), Ground Water

AR 035003. Attachment F table comparing wetland mitigation projects — Vacca Farm, Miller Creek Buffer, Tyee Golf Course, and Auburn Wetland — against Society of Wetland Scientists (SWS) criteria including reinstatement of driving ecological processes, restoration integrated into the landscape, restores a persistent resilient system, results in historic wetland conditions, and performance standards based on

Exhibit AR034998-AR035000, Attachment E: Summary table of compensatory mitigation (on-site and off-site) for watershed, wetland, and stream impacts at Seattle-Tacoma International Airport related to third runway embankment and South 154th Street relocation. Details on-site permanent impacts including filling approximately 980 linear feet of Miller Creek channel, filling 8,500 cy of Miller Creek floodplain, and filling

Attachment D table summarizing wetland mitigation credit for Seattle-Tacoma International Airport Master Plan Update improvements. Documents in-basin mitigation (102.27 acres, 29.80 credit) and out-of-basin mitigation (65.38 acres, 42.91 credit) for a total of 167.65 mitigation acres and 72.71 total credit. In-basin mitigation includes wetland restoration at Vacca Farm (credit ratio 1:1), wetland enhancement at Vacca