902 PINE ST NORTH SOUND BEHAVIORAL HEALTH TREATMENT CENTER 2025-11-04

I The project site's developed drainage patterns are analyzed and discussed in further detail in 1 Section 4.0 of this report. 1.4 Project Classification • I Per the City Manual, the project is classified as a Redevelopment Project. 2.0 Minimum Requirements I The new and replaced impervious area surface of the project exceeds 5,000 square feet, thus all Minimum Requirements (MRs)are triggered. Based on the memorandum issued by the City of Everett Public Works Department dated July 17, 2018, the site is located in the combined storm/sewer area. Stormwater shall be managed in accordance with the City Manual, along with Interim Policy 2-11, which amends MR 7— Flow Control by replacing the term "a land of forested cover"with "the existing site conditions"and deletes MR 6—Runoff Treatment. Refer to Appendix A-3 for the Developed Conditions Map. Below is a summary of how the project will meet MRs 1 through 9 for the TDA. • MR 1 —Stormwater Site Plans Preparation: This Stormwater Site Plan Report provides the narrative and analysis for the stormwater site plan and accompanies engineered drawings. Both have been developed by a licensed civil engineer and per Volume I, Chapter 2 of the City Manual. • MR 2—Construction Stormwater Pollution Prevention: Because the project is adding more than 2,000 square feet of new and replaced impervious surface and is less than 1 acre of land disturbing activity, the project qualifies for a simplified Construction Stormwater Pollution Prevention Plan (CSWPPP) if deemed appropriate by Permit Services. A CSWPPP will be prepared and included with the final report. • MR 3—Source Control of Pollution: Best Management Practices (BMPs) have been selected per Volume IV of the City Manual for use post construction and are discussed in Section 5.1. Source Control BMPs are included in the Operation and Maintenance (O&M) Manual for the owner's reference. • MR 4—Natural Drainage Systems and Outfalls Preservation: The existing onsite drainage system discharges to a public combined storm/sewer. The proposed system will continue to discharge to the existing onsite drainage system, thus maintaining the existing drainage patterns. • MR 5—Onsite Stormwater Management(OSM): The project has provided OSM to the maximum extent feasible without causing flooding or erosion impacts, as described in Volume III, Chapter 12 of the City Manual. Refer to Section 4.2 of this report for more detailed information. • MR 6— Runoff Treatment: The project site is exempted from Runoff Treatment according to Interim Policy 2-11. • MR 7— Flow Control: The project creates and/or develops more than 2,000 square feet of impervious area. According to Interim Policy 2-11, flow control shall be provided to match existing site conditions for the range of pre-developed discharge rates from 50 percent of the 2-year recurrence interval peak flow up to the full 50-year peak flow. Refer to Section 4.0 for a summary of the flow control analysis that shows compliance with this requirement. • MR 8—Wetlands Protection: No wetlands are located within the project site. I • MR 9—Operation and Maintenance: An O&M Manual is provided in Appendix E. Stormwater Site Plan Report North Sound Behavioral Health Treatment OMOM AHBL No.2170857.10