Resolution 3528 - Laserfiche WebLink

• Condition Number A.4, page 14, of the Decision Document determines that sufficient detention exists to control stormwater for the proposed action in the main fork of Powder Mill Creek to a peak discharge of 49 cubic feet per second (cfs) during a 25 year, 24- hour storm. • The 1988 Drainage Basin Plan contains peak flow discharge standards of 49 cfs from the Boeing site into the main fork of Powder Mill Creek and was adopted by the City Council on October 5, 1988. • The City's SEPA policy for water includes the following policy: "to encourage development and construction procedures which conform to the South Everett Drainage Basin Plan..." • The formally adopted standards in the Powder Mill Gulch Drainage Basin are the policies applicable to development proposed within this drainage basin. • Expansion of stormwater facilities to limit flows during 100-year storm would provide additional protection of downstream resources. Conclusions: • The stormwater treatment system in the main branch of Powder Mill Creek drainage basin will treat most of the stormwater prior to discharge into Powder Mill Creek. • The Decision Document and existing federal, state and local regulations require source controls for areas with concentrations of potential pollutants (see Findings&Conclusions: Sand Peat Filter System above). • Mitigation by the Decision Document has been required to be consistent with existing City drainage policy, and formally adopted SEPA policies and is supported by the record. • Appellants have not demonstrated that the Decision of the Responsible Official is unreasonable or that modification is justified. • Requirements placed on Boeing are consistent with the 1988 Powder Mill Gulch Drainage Basin Plan Update adopted by City Council. • The record demonstrates that impacts generated by the 1990 Boeing Master Development Plan have been mitigated in accordance with formally adopted City SEPA policies. 18