2201 100TH ST SW AD SYSTEMS 2022-03-07

AD SYSTEMS EXPANSION EVERETT,WA Minimum Requirement#1: Stormwater Site Plan Preparation All projects meeting the thresholds in Section 2.4 shall prepare a Stormwater Site Plan for City of Everett review. Response: A stormwater site plan has been prepared for the re-development. The stormwater site plan includes the design drawings and this report. No changes to the storm water flow patterns and existing quality and quantity facilities are proposed. Minimum Requirement#2:Construction Stormwater Pollution Prevention (SWPP) All new development and redevelopment projects are responsible for preventing erosion and discharge sediment and other pollutants into the receiving waters. Projects in which the new, replaced, or new plus replaced impervious surfaces total 2,000 square feet or more, or disturb 7,000 square feet or more of land must prepare a Construction SWPP Plan (SWPPP) as part of the Stormwater Site Plan. Each of the twelve elements must be considered and included in the Construction SWPPP unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the narrative of the SWPPP. Response: The 12 elements of a SWPP are addressed in the Construction SWPP section of this report.A full Construction SWPP will be prepared for the site before construction begins. Minimum Requirement#3: Pollution Source Control All known, available and reasonable source control BMPs shall be applied to all projects. Source control BMPs shall be selected, designed, and maintained according to Volume IV of the manual. Response:All available and reasonable source control BMPs have been applied to this project.These include, but are not limited to, Dust Control at Disturbed Land Areas, Landscaping and Lawn/Vegetation Management, and installation of erosion control BMP's during construction. Minimum Requirement#4: Natural Drainage Systems and Outfalls Preservation Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and downgradient properties.All outfalls require energy dissipation. Response:No significant changes to the existing drainage patterns and outfalls are proposed as a part of this re-development project. Portions of the existing conveyance system are being replaced to accommodate grade changes around the building expansion. Minimum Requirement#5:On-site Stormwater Management Projects shall employ On-site Stormwater Management BMPs to infiltrate, disperse, and retain stormwater runoff onsite to the maximum extent feasible without causing flooding or erosion impacts. Roof Downspout Control BMPs, functionally equivalent to those described in Chapter 3 of Volume III, and Dispersion and Soil Quality BMPs, functionally equivalent to those in Chapter 5 of Volume V, shall be required to reduce the hydrologic disruption of developed sites. NOVEMBER 20, 2017 STORMWATER DRAINAGE SUMMARY PAGE 6