TagPollution Control Hearings Board(1532)

This document outlines a Water Quality Assessment (WQA) conducted in support of the Port of Seattle's Master Plan Update for Seattle-Tacoma International Airport (STIA), focused on evaluating the airport's ability to meet water quality requirements under its NPDES permit following construction of a proposed third runway. The assessment uses three approaches: a Water Effect Ratio (WER) study to adjust water quality standards for site-specific conditions, a mixing zone analysis to determine where standards must be met in receiving streams, and an examination of variability in stormwater quality. The goal is to reach agreement with the Washington Department of Ecology on whether aquatic life in nearby receiving streams will be adequately protected.

This research study examines how heavy metals in highway stormwater runoff behave as water flows off pavement, finding that most heavy metals remain dissolved rather than attaching to solid particles due to low alkalinity and short travel times on the pavement surface. The study, conducted on Interstate 75 in Cincinnati over two years, explores how best management practices like detention basins or infiltration trenches could be used to capture these metals before they reach receiving waters.

Reference list compiled by Peter Willing, Ph.D., of documents relied upon in testimony regarding the 401 Water Quality Certification for the Third Runway at Sea-Tac Airport. Sources cited include studies on highway runoff chemistry, heavy metals partitioning, urban stormwater BMPs, treatment wetlands, NPDES permits, and Port of Seattle annual stormwater monitoring reports (1998–2001). Key references

This document is a reference bibliography (Exhibit B) listing scientific and regulatory sources related to environmental monitoring at Seattle-Tacoma International Airport. It includes studies on stormwater quality, aircraft de-icing and anti-icing fluid toxicity, aquatic habitat assessment, and sediment guidelines, drawn from sources such as the Port of Seattle, Parametrix Inc., and various environmental agencies. The references support environmental compliance reporting under the airport's NPDES stormwater permit.

This document outlines wetland mitigation calculations for the Vacca Farm site, detailing compensation actions such as wetland restoration and enhancement across various locations including Lora Lake and prior converted croplands. Adjustments were made to credit acreages based on state ecology findings and documentation gaps; for example, the 6.60-acre converted cropland credit was reduced to 3.30 acres because the state identified those areas as existing wetlands requiring enhancement ratios rather than restoration ratios. In total, the site's original 10.48 credit acres were adjusted down to 5.61 acres after accounting for these regulatory and documentation considerations.

City of SeaTac Municipal Code section 15.30.340 and King County Code section 21A.24.360 establishing stream development standards and minimum buffer requirements from the ordinary high water mark (OHWM). Specifies buffers for Class 1 streams (100 feet), Class 2 streams used by salmonids (100 feet), Class 2 streams not used by salmonids (50 feet), and Class

Exhibit 696 placeholder page indicating the document was not present at time of scanning. Administrative record reference AR 026131.01. No substantive content available; document absent from scanning batch.

This document is a placeholder page indicating that Exhibit 691 was not available at the time of document scanning. It is associated with administrative record reference AR 025988.01. No substantive content is present.

This document is a 30% design submittal prepared by HNTB Corporation for the Third Runway Embankment Construction Phase 4 project at Seattle-Tacoma International Airport. It is an oversized engineering exhibit, submitted without a date, representing an early-stage design milestone in the ongoing construction of the airport's third runway. The submittal is part of the administrative record (AR 025787) related to the runway expansion project.

This document outlines the Port of Seattle's step-by-step process for applying water quality standards at a specific site, focusing on copper toxicity testing in local waterways. The flowchart guides researchers through a series of studies — including screening, range-finding, and definitive toxicity tests using waterfleas and fathead minnows — to determine whether copper levels in outfall and receiving waters pose environmental risks. Depending on test results and regulatory approval from the Washington State Department of Ecology, the process may lead to a Water Effect Ratio (WER) study or a Translator Study.