TagMiller Creek(254)

Memorandum dated October 30, 2001 from Michael Kenrick of Hart Crowser, Inc. to Jim Thomson of HNTB (project number 4978-06), CC Elizabeth Leavitt of Port Of Seattle, regarding wetland hydrology impacts of the Third Runway Embankment Fill at Sea-Tac Airport. Covers depression wetlands, slope wetlands, and riparian wetlands; references FEIS for the Master Plan Update

These draft meeting notes from October 30, 2001 document a technical review session in which Port of Seattle consultants disclosed and explained several errors found in the low streamflow modeling for the Sea-Tac Airport Third Runway project. The key errors included a 1/24th magnitude conversion factor mistake in embankment fill data input, incorrect input files used for embankment modeling, and an overlap in which approximately 8 acres of the Walker Creek embankment appeared to be counted in both the Hydrus embankment model and the HSPF stream model. The meeting outlined corrective steps to be taken by the Port's consulting team to fix these errors before finalizing the revised Low Streamflow Analysis required under 401 Permit conditions.

Final meeting notes from October 30, 2001 Low Flow Analysis meeting regarding Port Of Seattle’s revisions to the Low Streamflow Analysis and Summer Low Flow Impact Offset Facility Proposal per 401 Permit conditions for Sea-Tac Airport Third Runway. Attendees included Ann Kenny (Dept. of Ecology), Kelly Whiting and David Masters (King County), Lisa Scott (Corps

This technical memo from Hydrocomp, Inc. (authored by Norm Crawford) outlines recommendations for improving hydrological computer modeling of Miller, Walker, and Des Moines Creeks near Seattle-Tacoma International Airport's new runway construction. It describes how rainfall and runoff from the new impervious runway and taxiway surfaces and surrounding pervious grasslands are tracked through a linked series of models (HSPF, Hydrus, and Slice) to estimate groundwater movement and seepage through underlying soil layers. The document identifies several discrepancies in the existing model setup and recommends corrections to better account for water flow paths, drainage areas, and groundwater recharge in the fill areas created by airport expansion.

In this October 24, 2001 letter, the Port of Seattle notified the Washington Department of Ecology of a mathematical error discovered in hydrological modeling software used to assess the Seattle-Tacoma International Airport Master Plan's impacts on Miller and Walker Creeks. The error caused stream flow impacts to be overestimated at 1/24th of their actual value, meaning required mitigation facilities could be smaller than originally planned. As a result, the Port requested an extension of the Low Streamflow Analysis submittal deadline from November 5 to November 21, 2001.

Declaration of Amanda Azous filed in Pollution Control Hearings Board (PCHB) cases No. 01-133 and No. 01-160, Airport Communities Coalition (ACC) v. State of Washington Department of Ecology and Port Of Seattle. Azous argues Port Of Seattle’s wetland hydrologic monitoring is inadequate for Section 401 Certification No. 1996-4-02325 and CZMA concurrency statement. Document addresses Wetlands

Declaration by Amanda Azous filed in PCHB Case Nos. 01-133 and 01-160 (Airport Communities Coalition v. State of Washington Department of Ecology and Port Of Seattle) in support of ACC’s reply on motion for stay of Section 401 Certification No. 1996-4-02325 and CZMA concurrency statement. Azous asserts scientifically substantiated harmful impacts to Miller Creek, Walker

Declaration by Dr. John Strand, Principal Biologist for Columbia Biological Assessments, filed in PCHB cases No. 01-133 and No. 01-160, in support of ACC’s motion to stay Section 401 Certification No. 1996-4-02325 (Amended-1) issued by Washington Department of Ecology for USACOE Public Notice 1996-4-02325 regarding Seattle-Tacoma International Airport (STIA). Strand addresses metals exceedances — copper,

Draft memorandum dated October 5, 2001, from Todd Pollard and Linda Logan to Port Of Seattle project files (project number 556-2625-002), summarizing chemical analysis of STIA receiving stream samples collected January 14, 1999 during a storm event with 86-hour antecedent dry period and 1.18 inches of rainfall. Samples collected from 8 locations including SDS-3, Miller

Declaration of Paul S. Fendt (Parametrix, Inc.) filed in PCHB No. 01-133, Airport Communities Coalition v. Department of Ecology and Port Of Seattle. Fendt, a stormwater engineer with 18+ years experience, addresses stormwater management and low flow mitigation for the Sea-Tac Airport Master Plan Update (MPU). Covers hydrology of Miller Creek watershed (8.1 sq mi,