2023-04-11-minutes-solid-waste-and-maintenance

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Street improvements include concrete curb/gutter, sidewalks, street lighting, permanent signage, asphalt, asphalt markings, gravel base, storm drainage, and other items associated with minimum public improvements consistent with Public Works Development Standards. Driveway locations will be reviewed to meet standards. Any gates will need to be set back from the sidewalk to allow queuing of cars without obstructing the sidewalk. Also, any damaged sidewalk during construction will need to be fixed per the Development Standards. Specific issues related to site construction will be addressed at project civil submittal. Storm water: There is a storm system that runs north/south in Water St. This storm connection point may be used as an out fall after treatment and flow control is met. Additional storm calculations will be required to verify capacity of the existing systems if used for an outfall. Storm drainage development will need to follow the City's standards at time of building permit application. City staff will work with the applicant for appropriate treatment and flow control for the onsite storm drainage. The applicant shall use the current Stormwater Management Manual for Eastern Washington, or approved equivalent for reference in design of stormwater treatment and flow control for post construction requirements for new development and redevelopment. The design shall at a minimum use the following design storms, or as recommended for the proposed BMP, whichever is greater. Treatment shall be designed for the first '`/2" of rainfall on the property, and storin drainage detention on a 10 year storm event (1.2"of precipitation/24 hours) and retention facilities based on a 25 year storm event (1.6"of precipitation/24 hours). Specific issues related to storm water will be reviewed at time of civil plan submittal. The applicant's design engineer should determine groundwater elevations in the vicinity of proposed storm water treatment and flow control facilities. The water surface elevation needs to be utilized in the facility designs and should be verified when groundwater is at its highest. Typically the groundwater in the Ellensburg area is elevated from April 151' through October 15`t'. However, groundwater on the subject site may not be associated with seasonal irrigation and could crest at another time during the year. The following comments are from the City Stormwater Department; 1. If the site is an acre or greater the developer will need to make Notice of Intent (NOI) with Ecology and apply for a Stormwater General Construction Permit months in advance of construction. https:Hecology.wa.gov/Regulations-Permits/Permits-certifications/Stormwater- eneral-pemiits/Construction-stormwater-permit 2. The Ecology permit requires a Storinwater Pollution Prevention Plan (SWPPP) be submitted with the plain set and be reviewed by the City of Ellensburg Stormwater Utility along with a set of temporary sediment erosion control plans (TESC). 3. In addition, Ecology now requires an Operation and Maintenance (O&M) Plan be submitted to the City for review and retainage. The O&M Plan must address the long tern maintenance of the stormwater facilities (swales) that will be constructed onsite to deal with the flow control and treatment requirements of Core Element 5&6 in the Eastern Washington Stormwater Management Manual. P:\Projecls\Public Works\2033 23-063 Water Street & 6th Avenue - Counly Parking Lot\Water St & 6th Ave - County Parking Lot P23-066.doex