2202 100TH ST SW 2023-02-07 - Laserfiche WebLink

J x 0 0 5. Include the Operation and Maintenance Manual as a separate document. Include the specific O&M requirements for the modular wetland. 6. Flow Control / Treatment Trade c. The flow control trade of Basin D for Basin B appears to be inadequate as Basin D has less total and impervious area. Please provide a POC analysis for all basins to show that the duration standard is being met. d. Basin D collects less impervious area than Basin B. Please address whether the Basin D for Basin B trade provides equivalent treatment. 7. Provide a printout of the diagrams used for the WWHM model as well as the graphs. 8. Verify the impervious area for Basin C in the Rational Method calculations. Based on Everett mapping and the Basin Map figure, there appears to be more than 4.2 acres of impervious surface in Basin C. 9. Some of the plan set rim elevations and invert elevations do not match the StormCAD inputs. Please revise. 10. Access lids larger than the standard manhole lids shall be hinged and shall be capable of being opened and held open by a single individual. Please include this in your plans, including the detention vault access grate. Also, note that all access lids shall be equipped with a pick hole capable of being opened with a standard grate hook or handles. [DCSS 4-4.2(3)] 11. Is an additional access point needed for Cell 1 in the detention vault? The Manual requires that access openings for detention vaults be positioned at a maximum of 50 feet from any location within the vault. 12. See the attached structural design vehicle loading for the detention vault. Our policy is to have the capability to bring City trucks onsite to vactor/jet the structure if the owner is not maintaining it. You will need to submit structural calculations, but this can be deferred to construction as a permit condition. 13. Outfall Riprap Pads e. The riprap pads at the outfalls must be designed according to DCSS 4-2.5(1). f. Include the riprap specifications for the outfalls from DCSS Table 4-2.1 with the plan set. g. Note that when designing the riprap pad, the perforated pipe is not equivalent to the use of a dispersion trench to distribute the flow out into a sheet flow condition. 14. Proposed Drainage Swale [See DCSS 4-2.6(1)] h. Note that the swale shall be compacted to a minimum of 95 percent compaction as verified by a Modified Proctor test. Include this with the plan set. i. The swale must have riprap filters as specified in DCSS 4-2.6(2). Include this with the plan set. 15. Where will the retaining wall perforated pipe drain to? 16. A hold harmless agreement is required for the public ROW runoff that will flow to the site's Stormwater system. We do not have a template for the agreement but can work with you and our counsel to develop one. 17. Complete the Declaration of Covenant and Grant Easement for Inspection and Maintenance of Stormwater Facilities and BMPs, which is located here: https://everettwa.gov/1985/Stormwater-Technical-Resources under "Permitting Resources." Thank you, Cindy _ Cindy Cullen, P.E. Stormwater Plans Reviewer I Associate Engineer PE I City of Everett Public Works 425.257.8894 13200 Cedar Street, Everett, WA 98201 EVERETT everettwa.gov I Facebook I Twitter Note: Emails and attachments sent to and from the City of Everett are public records and may be subject to disclosure pursuant to the Public Records Act. 1Q