TagStormwater(373)

A September 2000 letter from Northwest Hydraulic Consultants raises concerns that the Seattle-Tacoma International Airport's Stormwater Management Plan fails to adequately assess or mitigate the third runway embankment's impact on stream base flows and seepage flows to nearby wetlands. The consultants argue that the Port of Seattle's own data contradicts its claims that the embankment fill would maintain groundwater recharge, and that independent re-analysis suggests summer groundwater reductions to Miller Creek could be roughly twice what the Port reported. The letter calls for more rigorous and consistent hydrologic modeling before construction commitments are made.

A September 2000 letter from Northwest Hydraulic Consultants, written on behalf of the Airport Communities Coalition, raises serious technical concerns about the Stormwater Management Plan for Seattle-Tacoma International Airport's proposed third runway. The letter highlights findings from King County reviewers showing that multiple stormwater facilities in the plan were unverified, potentially infeasible, or unlikely to meet required flow control performance standards. The consultants argue that the review timeline was insufficient and that the Port of Seattle had a history of failing to deliver promised stormwater mitigation measures.

In September 2000, Northwest Hydraulic Consultants submitted preliminary technical comments on behalf of the Airport Communities Coalition, raising serious concerns about the adequacy of the Stormwater Management Plan for Seattle-Tacoma International Airport's proposed third runway expansion. The letter highlights findings from King County's independent review, which identified numerous cases where proposed stormwater control facilities were unverified, infeasible, or unlikely to meet required flow control performance standards. The consultants warned that the compressed public review timeline was insufficient for thorough evaluation of the plan before Ecology's 401 Certification decision.

A water resources consultant hired by the Airport Communities Coalition reviewed Sea-Tac Airport's August 2000 Stormwater Master Plan and found it seriously deficient in protecting local water quality. The review concludes that existing pollution controls at the airport are not working, that stormwater discharges regularly violate Washington State Water Quality Standards, and that the Plan's proposed measures fail to provide reasonable assurance that those standards will be met in the future. Key concerns include the diversion of polluted runoff away from local creeks, inadequate handling of metal roof runoff, and the lack of meaningful mass-balance accounting for long-lived pollutants.

In September 2000, King County's Department of Natural Resources provided a technical review of the Port of Seattle's Comprehensive Stormwater Management Plan (SMP) for proposed Master Plan Update improvements at Seattle-Tacoma International Airport. The review found no fatal flaws in the plan's approach to meeting King County's stormwater standards, but identified inconsistencies in flow control calculations and water quality measures that needed to be resolved before final permitting. King County also emphasized the importance of rigorous erosion and sediment control during construction and recommended that Ecology and the Port establish a joint compliance team to oversee implementation of the complex, multi-year project.

A September 2000 letter from the Airport Communities Coalition to the Washington State Department of Ecology raises concerns about the adequacy of Seattle-Tacoma International Airport's Stormwater Management Plan submitted for 401 Certification. The letter identifies potential flaws in the analysis of base flow impacts on Miller Creek, inconsistencies between the new plan and earlier natural resource mitigation documents, and concerns about proposed changes to watershed basin boundaries. The authors argue that insufficient time was provided for proper review and that the plan fails to fully account for cumulative water quantity impacts of future development.

A September 7, 2000 letter from Northwest Hydraulic Consultants to the Washington State Department of Ecology raises concerns about the adequacy of the Port of Seattle's Stormwater Management Plan for Sea-Tac Airport's Master Plan expansion. The letter identifies significant technical discrepancies in the plan's analysis of baseflow impacts on Miller Creek, questions the reliability of proposed water-rights acquisitions as mitigation, and flags inconsistencies between the stormwater plan and the Natural Resource Mitigation Plan. The consultants also object to the limited time provided for independent review of the four-volume plan and warn that cumulative water quantity impacts of future commercial development in the airport acquisition area have not been adequately assessed.

This document contains a September 2000 email exchange regarding the proposed expansion of Lagoon #3 in the Sea-Tac Airport Industrial Wastewater System (IWS), in which consultant Bill Rozeboom follows up on unresolved comments submitted to the Washington State Department of Ecology. The attached July 31, 2000 comments raise concerns about discrepancies in the lagoon's design capacity, the risk of frequent overflow into Des Moines Creek, and potential wildlife hazards near aircraft movement areas that may violate FAA guidelines. Additional issues flagged include incomplete construction plans, unaddressed lagoon deficiencies, and the apparent overlap of the lagoon expansion project with 3rd runway construction activities affecting nearby wetlands.

Memorandum from Brian Pippin (Parametrix, Inc.) to Linda Logan (cc: John Brooker), dated August 14, 2000, Project Number 556-2912-001, Port of Seattle WERs. Discusses critical conditions for Water Effect Ratio (WER) sampling per the Permit Writers Manual for the third runway treated stormwater discharge into Miller Creek. Uses HSPF hindcasting over 49-year period to evaluate

Email dated August 10, 2000 from Kate Rhoads to Kelly Whiting transmitting a Word document (POS-Cu.doc) containing technical comments on copper (Cu) levels in stormwater runoff from Seattle-Tacoma International Airport (STIA) runways. AR017903-017904. Comments address total recoverable (TR) copper median concentration of 37 ug/l versus the dissolved fraction surface water acute toxicity standard of 4