9404 18TH AVE W 2018-01-01 MF Import

L Project iDvcrvicw The proposed development is � 1.81 acre site located on [he west side of I&"' Ave. West in Everett, Washington. The project is made up of two adjoining parcels. The eastern most paicel is located at 9406 18ih Ave. W. 'I'he proposed project consis[s of developing the site into eight detaclied townhomes widi associated road, storm drninage and utility features. The site currendy has one single-family residence and one large garage with boat storage. One Ca[egory I wedand and a Type 3 stream were identified on the western portion of the site. Vegetation on site consists of grnss, deciduous trees and shrubs. The developed site conditions will inciude eight single family de[ached townhomes, approximately 285 linear feet of paved rond, fronta;e improvements, one NGPA/ETract. Pervious areas are modeled with � CN of 86 (grass). Runoff from the property frontage will be collected in catch bnsins and transported through a 12-inch diameter pipe to a 36-inch di�meter pre-settling pipe that is approximately 30 feet long. Runoff from the driveway access ro�d will be collected in catch basins and trunsported dvough pipes to a second underground pre-setding pipe. This pipe is 36 inches in diameter and 14 feet long. It is located west of the 30 pre-setding pipe. The 30' and the 14' pipes release runoff to a 12" CPP that is 9 feet long. From here drainage enters a 60" underground detention pipe thlt is 125 long. This pipe will be located under the drivewny area. The detention pipe will release dirough a control svucture to a Storm Filter Manhole to the north. The Stonnfilter Manhole will be m�nufactured and maintnined by Contech (Pormerly Stormwlter 360). From here, drainage will flow northwest through a 57' pipe to � Ievel spreader where it will release to the wetland on the western portion of the site. II. Prcliminary Conditions Sammary The site has one basin that drains toward the west. The proposed development will retain the existing drainage pattern and will not change the character of the basin. Drainage on site is limited to ruof drains and splash blocks.