6624 BROADWAY 2018-01-02 MF Import

1. Project Overview Habitat for Humanity proposes to construct four single family residential units on the project parcel. Associated improvements will include utility services, grading and a paved driveway. Stormwater improvements will be required as described herein. U. Pre -Developed Conditions The site currently has an existing residence and garage which are in the process of being demolished. Onsite drainage is by sheet flow to the south into a neighboring parcel, then into the city stormwater facility. 111. Off -site Analysis 111.1 Upstream Analysis Little or no area drains into the site from adjacent parcels. It is not anticipated that the site stormwaler system will receive sufficient flow from offsite to impact the analyis. 111.2 Downstream Analysis The Monagan Mor development of Habitat for Humanity of Snohomish County is located at 6624 Broadway in the south ccrlral portion of the City of Everett. The project proposes to discharge via a e.d catch basin constructed on the existing City storm main within Broadway. (Sec attached portion of the City of Everett CIS storm sewer map.) Because of the exis,ing shallow storm sewers immediately adjacent to the site, a portion of the downstream 12" storm sewer is proposed to be replaced in kind but at a greater depth. The existing storm scwcr will be intercepted between CB U14 and CB X10. The existing storm sewer between this new catch basin and CMH X7 ;including CB X 10) will be replaced at a grade, of 0.005. CMI4 X7 is a deep manhole of approximately 8 feet, which allows for lowering of the line. Flow from CMH X7 continues southerly approximately 85 feet to DMH X6 through a 24" storm drain. From there it flows easterly across Broadway to CB X12 through an 18" pipe for approximately 100 feet. CB X12 is considerz' ;y lower than C13 X6. The slope is estimated to be 0.18. blow turns northerly for approximately 60 feet to CB XI through an 18" pipe within Howard Ave. It then turns easterly along Howard Ave in an 18" pipe and passes through CB X22, CB X13 and CB X14 until it reached CB X18 which lies in the WSDOT right- of-way of 1-5. Al this point the pipe system turns southerly, still in an 18" pipe, and passes beneath the 1-5 sound wall. The continuation downstream can not be followed onto WSDOT right-of-way; however, the City's GIS maps show it continuing completely across 1-5 in a pipe system. The total length of observed system is approximately 700 feet. There are no indications that any problems exist within the City owned system. Habitat for Humanity- Monagan Mor Page 1