6502 EVERGREEN WAY ENHANCED SERVICE FACILITIES 2020-01-21

PUBLIC WORKS 3. MR#5:0n-Site Stormwater Management—must be addressed for the project using either the performance standard or the list method. If the list method is chosen document the feasibility/infeasibility determination for the progression through the list. Specific infeasibility criteria must be cited. Note that if infeasibility is based on infiltration rate or potential, a PIT test will be required to document the infiltration rate. It appears that perched groundwater and/or impermeable layers may make some on-site BMPs infeasible. 4. MR#6: Water Quality Treatment—must be provided in accordance with the manual. Per Sep 5 of Section 2.1, Volume V of the Manual the project will be required to provide enhanced treatment as it is considered a commercial project. 5. If MR#7: Flow Control—is applied to replaced surfacing as well as new the site will need to provide stormwater flow control in accordance with Volume III of the Manual. The pre-developed conditions will be forested for all replaced pavement, rather than existing conditions. 6. Please provide the O&M manual as a standalone document(can also be included in the stormwater report for convenience.) Please include the following information on the cover page or other prominent location within the document: • the party responsible for maintenance and operation, • the requirement for the O&M Manual to be retained on or within reasonable access to the site, • the requirement to transfer the Manual to any new property owner along with the property, and • the requirement that a log of maintenance activity be kept and made available for inspection by the City upon request that indicates what M&O actions were taken shall be kept. 7. Section 2 of the Storm Drainage Report notes that the NRCS classifies Alderwood soils as Class B. However, the Manual classifies Alderwood soils as a Class C soil (Volume III, Table 2.3.1). In the City's experience the soils in this area behave more like a Class C soil. Calculations for the site should be based on Class C or Till soil types. 8. The Offsite Analysis section of the report shall address run-on from the adjacent property. If runoff from areas outside the site flow to the treatment facilities,they must be included in the treatment calculations. 9. The Offsite Analysis section shall address the city drain pipe which runs through the site, and shall generally describe the tributary areas. Page 4of5