8525 EVERGREEN WAY BURGER KING 2021-05-10

E v 6. Provide a Permanent Stormwater Control Plan Section in the drainage report which provides the information noted in Section 3.1.5,Volume I of the SWMM. 7. Include a list of other necessary permits and approvals as required, if those permits or approvals include conditions that affect the drainage plan, or contain more restrictive drainage-related requirements. If no other permits and approvals are required, state that in this section. 8. MR#5 may be met for this project either by applying List#2 or the LID Performance Standard per Section 2.5.5,Volume of the SWMM. The documentation provided in the Drainage Report does not comply with either method. The related section 4 of the Drainage Report needs to be updated to state which method was selected and to thoroughly document compliance with that selected method. 9. Note that the Drainage Report indicates that landscaping islands will be used for bioretention, but Sheet 3 of the drawings 1- indicates that rain gardens would be used. Rain gardens are not allowed for projects that trigger MR#1-9. Bioretention t designed in accordance with BMP T7.30 is required instead. Further, Sheet 3(Grading and Drainage Plan) does not show r4 proposed bioretention facilities in the plan view.They are shown on Sheet 4 (Stormwater Pollution Prevention Plan), but o 4 ' they and any other BMPs ultimately selected from List#2 or the LID Performance Standard should be shown on the drainage plan since they will be part of the permanent stormwater control plan. vta As noted above, if Basins A and B represent two distinct TDAs,then on-site stormwater management requirements must be documented and met for each TDA, as applicable. 11. The first paragraph of the Drainage Report indicates that the project will not trigger water quality treatment requirements, as discussed during the preapplication meeting, but no justification is provided. The second paragraph then states that MR#1- 9 apply,which includes the requirement to provide water quality treatment. Additional documentation is needed to clarify MR applicability and how the applicable requirements will be met. See the related comments regarding MR#1. 12. The Drainage Report indicates that less impervious surface will be contributing to the downstream basins and does not describe any flow control facilities.The plans also do not show flow control facilities. However, the second paragraph of the Drainage Report indicates that MR#1-9 apply, and the WWHM modeling provided at the end of the Drainage Report includes trapezoidal ponds and gravel trench beds.The Drainage Report must clearly establish which MRs apply and why flow control BMPs are not provided if in fact MR#7 does apply. See the related comments regarding MR#1. Note that under the current standards a reduction in impervious surface may not be sufficient to comply with flow control requirements if MR#7 is applied to replaced surfaces. 13. The Drainage Report indicates that no wetlands are on site.Additional documentation needs to be provided to determine whether the project site discharges to a wetland, either directly or indirectly through a conveyance system, and if so, how those wetlands would be protected. 14. The Drainage Report refers to an attached O&M Manual, but none was provided. Please provide a standalone O&M Manual, and reference it in the Drainage Report. The O&M manual should include the following: • 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 O&M 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. The log must indicate what O&M actions were taken. 15. The O&M Manual should incorporate maintenance requirements from the 2013 Western Washington LID O&M Manual prepared by the Washington State Department of Ecology, as applicable, depending on the final BMP selection. See related BMP selection comments regarding MR#5, 6, and 7 above. 16. Detailed review of the construction plans was not conducted as resolution of some of the comments above may significantly alter the project design. 2/ �