2300 MERRILL CREEK PKY OPUS NW 2018-01-01 MF Import

� 1.0 PROJEC'C OVERVIEW The proposed project is an approximate 3.2-acre site located in a portion of Section 2, Township 28 Nonh, Rangc 4 East, Willamette Meridian, Ciry of Everett, Snohomish Counry, Washington. More pacticularly, tl�c sitc lies within thc 2300 block of Merrill Creek Parkway located on the south side of the parkway and is comprised of the entire Lot SA of the Seaway Center development. The proposal for this devclopment is to constcuct parking, drive aisles, appropriate landscaping, and pipe conveyance with catch basin callection draining to a proposed srorm drainage wcddetention �nd, ultimatcly discharging off-site inro the right-of-way of Mercill Crcek Parkway, whcre runoff will then course in an eastedy dircction within the right-of-way �Ierrill Crcck Parkway in a pipe convcyancc system. The total volume required in the detenlion facilities proposcd for this development is 25,882 cubic feet, with the provided volume being 31,037 cubic fcet. The sizing for the detention pond was based on the Santa Barbara Urban Hydrograph (SBiJI-n methodology, which is an SCS-based methodology that has been adopted by the Ciry of Everett for usc in sizing detention and water qualiry fac[litics. Por purposes oC sizing detention, one-half of[lic 2-year pre-developed peak runoff rate is the rcleasc ratc during a 2-year/24-hour design storm. In addition, thc 10-yeadl00-yeur pre-developed peak runoff rates are the release rates during 10-ycar and 100-yead24-hour post-developed design stortns with a saCcty factor Uased on the amount of impervious surface coverage on the lot added lo the size of[he detention. This site was determined to bc 80 percent impervious when fully develuped. Access to thc sitc will be from Aie adjoining dcvclopment o�the west side oFthe project. For water qualiry purposes, dic wet pond will be locuted below de.ention prior to discharging � runoff from the project sitc. A stormceptor will be used for pretreatment prior to thc weddetention pond so that an access road dces not havc to be constructed to the bouom of the open water cclL Please refer to the Appendix for how the water quality was sizcd for this development. At this time, the project is proposing to construct t090-acre of parl:ing lot combined with a weddetention pond sized fur full buildoul of the project site. The frontage cunoff from on-site coosisting of the landscaped slope ares along the right-of-way of Merrill Creek Parkway will be collectcd at a new drivcway extension onto tlie site when fully built out. There will be no bypass from the site. This runoff will be pumped to thc pond. When Cully constructed in the future, the sitc will also have an t18,000•square-foot building on it. � 12230.W3.doc