3315 BROADWAY HOPEWORKS STATION 2 2020-12-21

I I 3. PROPOSED CONDITIONS When viewed from the Broadway frontage, the building will have four above grade floors. The floors consist of ground floor retail/program space dedicated to operation of a café and kitchen. The vision of Hopeworks II is to provide homeless housing and skills training in the food prep and service industry. The upper three levels will support approximately 66 units with a mix of sizes between studio, one, and two bedroom units. The roof top will contain a large photovoltaic Iarray (solar panels)with the goal of achieving net zero energy usage. Water and gas services are available in Broadway and will be brought into the building from the west. Sewer, storm (extended north from 34`h Street), and power are available in the alley and will be brought into the building from the east. Communication service is a design build service provided by the contractor, but it is anticipated those services will also come from the alley. Because of the kitchen component of the program space an appropriately sized grease interceptor is proposed to be located in the parking garage to mitigate fats, oils, and greases (collectively FOG) prior to discharge to the 12" existing sewer main the alley. Black water lines from toilets, and grey water lines from showers and bathroom sinks will not connect to the grease interceptor. Since the building is essentially a zero lot line project, the grease interceptor is shown and sized by the plumber and included in the plumbing plans for the project. The garage floor drains in the covered parking areas are considered building sewer and will drain to the sanitary sewer connection after passing through an approved oil/water separator. Again the design elements of the interior plumbing is the responsibility of the plumber and will be shown on their respective plans and specifications. ' As noted in the overview,the proposed project is required to limit the rate of stormwater leaving the site to the same rate that exists in the existing condition (surface parking lot with limited landscaping). Because the small amount landscaping that is being removed would result in slightly increase runoff it needs to be addressed by a flow control system. The project proposes to install a 3' diameter concrete detention pipe with three 60" diameter manholes (including the control structure) beneath the garage floor slab. The system will drain by gravity to the new extended 12"main in the alley. The flow control tee was modeled with a 1-5/8" lower orifice and notched weir. WWHM2012 modeling results are included in the appendix. Some building roof areas will be used as amenity space and will include intensive green roof and raised metal planter boxes. These areas are shown and detailed on the landscape plans for the project, and included in the appendix of this drainage report. Additional discussion is provided in section 4 of this report under MR 5. I Hopeworks II DCI Engineers Page 3 Storm Drainage Report