4110 CLIFF DR 2022-01-26 - Laserfiche WebLink

1. PROJECT OVERVIEW This document is intended to provide engineering information necessary to support the SFR building permit applications to the City of Everett for the proposed Single Family Residence (SFR) and driveway proposed on this two lot short plat. The site is located at 4110 Cliff Dr., Everett, WA 98203; refer to Figure 1 for a vicinity map. The gross short plat area is approximately 0.38 acres. The short plat consists of two lots. Lot 1 currently consists of mostly lawn with a few fruit trees, maple tree and deciduous tree. Lot 2 currently contains an existing SFR and concrete driveway. The existing structures on Lot 2 will remain and a new SFR is proposed for Lot 1. The slope of the short plat is moderate to steep and averages approximately 22 percent on Lot 1 down to the northeast toward Olympic Blvd. The proposed SFR will be located on Lot 1 and set approximately 20 feet from the west property line. The proposed driveway will take access from the existing roadway to the west (Olympic Blvd.). The existing SFR and driveway shall remain on Lot 2 and takes access from the existing roadway to the east (Cliff Dr.). Frontage improvements are proposed along Olympic Blvd but not Cliff Dr. for this project. This project proposes to construct less than 5,000 sf of new impervious surfaces. Therefore, minimum requirements 1-5 apply to all the new impervious surfaces for this project along with all the disturbed pervious surfaces. This proposal does not meet any of the land -use criteria that require specific source control for the final use and a SWPPP has been prepared to address the runoff from the site during construction. Refer to Sections 4 and 5 for a detailed discussion. Figures 2 & 3 are provided to show the existing and developed basins and runoff conditions for the short plat. The runoff from the pervious surfaces in the existing conditions will spread over the pervious, moderate to steeply sloped lawn to the northwest and drain toward the western property line. In the developed conditions, the runoff from the new roof will be collected by a perforated stub -out connection and directed to the existing/relocated ditch on the northwest side of Olympic Blvd. The general soil conditions for these properties were found to be Alderwood gravelly sandy loam. The drainage design has been laid out per the COE 2017 Stormwater Management Manual and the 2014 DOE Stormwater Manual. The downstream system for this project is comprised of roadside ditches, pipes and a stream. During the site visit there were no signs of flooding or capacity issues within the observed downstream systems. Due to the size of this project only Minimum requirements 1-5 apply to the proposed drainage design as noted above. Included on the following page is a copy of the MR flow chart out of the COE Drainage Manual showing how the applicable minimum requirements were determined. Reid SP 15-0714 July 2017 Page 3