TagPCHB(607)

A October 1999 laboratory analysis report from Aquatic Research Incorporated details water sample testing conducted for Parametrix/Port of Seattle. One water sample collected on October 8-11, 1999 was tested for total suspended solids, petroleum hydrocarbons (diesel and motor oil), and total metals including cadmium, copper, lead, and zinc. Results showed low levels of contaminants, with zinc detected at 0.102 mg/l and copper at 0.0070 mg/l, while diesel and motor oil levels fell below detection limits.

In this October 1999 internal memo, Washington State Department of Ecology staffer Tom Luster describes a meeting with his supervisor Paula regarding the agency's water quality review of Sea-Tac Airport expansion. Luster explains that he cannot yet provide 'reasonable assurance' that the Port of Seattle's proposal will meet water quality standards for Des Moines Creek, citing inadequate stormwater treatment plans and the Port's removal of flow augmentation measures from its mitigation plan. He expresses concern that management pressure to approve the project quickly could compromise the integrity of the regulatory review process.

A September 20, 1999 internal memorandum from Parametrix, Inc. consultants to Scott Tobiason provides technical review comments on the first draft of the 1999 Annual Stormwater Report for Seattle-Tacoma International Airport (STIA). The memo raises concerns about consistency in water quality comparators, statistical methods for 'trimmed' data sets, and the attribution of reduced sediment levels to construction wheel wash versus other factors. It also flags regulatory issues regarding mixing zones, water quality standards language, and potential NPDES permit compliance implications of identifying pollution sources in the annual report.

A 1999 technical memorandum from Parametrix, Inc. analyzes whether stormwater discharged near Des Moines Creek meets Washington State dissolved copper water quality criteria, using a Monte Carlo simulation model. The analysis finds that copper levels in the stormwater effluent consistently exceed water quality standards regardless of background ambient concentrations, with dilution factors generally less than 2. The study evaluates several potential remedies, including increased onsite detention, expanded mixing zones, and water effect ratio adjustments, finding that the Water Effect Ratio (WER) is the most influential factor in achieving compliance.

A 1999 technical memorandum from Parametrix, Inc. to the Port of Seattle analyzes the sensitivity of stormwater discharge compliance determinations for Sea-Tac Airport's runways, focusing on dissolved copper concentrations in Des Moines Creek. The memo evaluates whether mixing zones and dilution factors could offset elevated copper levels in stormwater runoff, finding that ambient copper concentrations already exceeded water quality criteria in 37–65% of samples. The analysis concludes that dilution factors based on streamflow alone are unlikely to be significantly greater than 1.0, though accounting for the Northwest Ponds' reservoir volume raises the estimated dilution factor to approximately 1.7.

A 1999 memo from the Washington State Department of Ecology evaluates construction techniques for a retaining wall near Miller Creek at Sea-Tac International Airport's Third Runway project. The memo concludes that specialized methods such as tied-back walls, bored piles, soil nailing, or ground freezing can address difficult underground soil conditions while keeping construction within the approved wetlands disturbance footprint, though at significant cost. The author also recommends installing monitoring devices in the wall and backfill to confirm the structure performs as designed throughout its service life.

This document is a section of Washington State's Permit Writer's Manual covering Water Effect Ratio (WER) methodology for water quality permitting. It outlines procedures for determining how receiving water conditions affect the toxicity of discharged effluents, including required toxicity testing species, sampling schedules at critical and non-critical flow conditions, and guidelines for freshwater and saltwater discharge situations. The document is unrelated to Sea-Tac Airport noise policy.

This 1999 email exchange between Washington State Department of Ecology staff debates the legal basis for requiring the Port of Seattle to restore water quality in Des Moines Creek as a condition of receiving a Section 401 water quality certification for the Sea-Tac Airport third runway project. The central question is whether Ecology can require a single applicant to fix broader watershed problems that pre-exist their project, or whether mitigation can only address the applicant's direct project impacts. Staff ultimately conclude that under antidegradation requirements, no further degradation of the creek can be permitted until existing beneficial uses are restored, meaning the Port's mitigation plan must include measures such as flow augmentation and stormwater controls to bring the creek into compliance with water quality standards.

In a June 1999 email chain, Washington State Department of Ecology staff member Roger Nye proposed bringing in an outside consulting firm (SAIC) to help review technical groundwater studies related to an environmental cleanup agreement (Agreed Order) at Seattle-Tacoma International Airport (STIA). The goal was to add credibility and independence to Ecology's review process, particularly in response to public demands for an independent assessment. Nye also requested that the Port of Seattle agree to cover SAIC's costs as part of the overall project expenses under state cleanup regulations (MTCA).

A 1999 internal email from Ken Ludwa to airport staff reports that upstream water quality data for Miller Creek and Des Moines Creek shows both streams exceed copper concentration standards, meaning neither is currently in compliance. The analysis suggests that applying a Water Effect Ratio (WER) adjustment of 2 or more for Des Moines Creek and 4 or more for Miller Creek could bring the streams into apparent compliance with water quality standards. The email also raises the possibility of conducting new clean sampling to potentially replace the existing non-compliant data.