1020 N BROADWAY EVCC STUDENT HOUSING - WHOLE SITE 2022-05-23

0 3. The comments below were generated from this project's Stormwater Reviewer. If you have any questions regarding these comments, please contact Arnie Roshak with the City of Everett Public Works Department/Sewer & Drainage Division (425-257-7249 or Aroshak@eve rettwa.gov). a. Sewer: i. Confirm sizing of existing side sewer to be reused for the sanitary side sewer connection. Pipe must be minimum 6-inch diameter. If smaller anew connection must be made to the main. Response: Agree. See the Sanitary Sewer memo showing that a 6" @ 2% is adequate. A note is added if a larger size is needed. b. Surface Water: i. Since this project is located in the combined sewer area, Interim Policy 2-11 for Stormwater Management in the Combined Area and the City's 2010 Surface Water Management Manual applies. Response: Agree. The Interim Policy 2-11 was used. ii. Section 4.1 states the project adds 10,000 sf— should this instead be adds or replaces more than 10,000 sf of impervious? The City's threshold is 5,000 sf, and minimum requirements #1-9 still apply. P ` - i hip -1 nuld be "replaces" more than 1.0,000 sf iii. Do not use MGS flood for conveyance sizing on small sites. Continuous runoff model is only used for conveyance sizing on large sites, with time of concentration over 60 minutes. Rational method is used for smaller sites. See volume 1, Chapter 5 of the COE 2010 Surface Water Management manual. Response: Rational method has been updated and added to the report. iv. Survey shows that the existing pipe in the ROW that the project discharges to is only 6- inches. Discharge to the 12-inch storm drain on the north side of 10tn. Minimum size for a public storm drain in the right-of-way is 12 inches, except for pipes less than 50-ft long from an inlet may be 8-inch. Revise proposed pipe in the ROW to 12-inches. Response: Relocated point of discharge to near the garage as only 6-inch pipes were available at the 2 catch basins in 10tn v. Proposed storm drain is too shallow to allow for use of PVC pipe. PVC pipe must have a minimum of 3-ft of cover. Lower pipe or provide other pipe material. Additional pipe materials options are listed in section 4-2.3(1) of the COE Design and Construction Standards and Specifications for Development Manual. Provide in accordance with Section 9-05 of the WSDOT/APWA standard specifications. Response: Agree. Updated to 3' of cover on all pipes in the right-of-way vi. Confirm sizing of existing side sewer to be reused for the private storm connection. Pipe must be minimum of 6-inch diameter in the right-of-way. If smaller than 6-inch a new connection must be made to the main. Inspect pipe to confirm condition prior to making connection. Add notes of this nature to the plans to direct the contractor and inspectors. Response: Agree. Notes were added for the contractor to video and to connect to main if needed. - (2 3 9/5/2018