2024 DRAINAGE IMPROVEMENTS

Project Description:

The purpose of the Work at the Broadview Site is to provide water quality treatment for street runoff by installing bioretention systems. This portion of the Project consists of the following elements of Work including but not limited to: construction stormwater erosion control ( submittal, implementation, and maintenance of the Construction Stormwater Pollution Prevention plans (CSECP/SWPPP, TVSPP, SP, & TDP)) ; health and safety plan; clearing and grubbing; demolition and removal of existing surface pavement, sidewalks, and curbs; potholing; excavation; temporary traffic control plan and implementation, including flagging; site preparation and staging; survey; removal and abandoning of existing drainage structures and piping; temporary stormwater bypass; protection, relocation, and/or adjustments of existing utilities, including water services; reconnection to the existing drainage system; installation of new drainage systems, including storm drainage piping, drainage structures, bioretention cells, and flow splitters; flow testing; install gate valves and assist SPU crews with water service and meter box relocations/adjustment; television inspections; side sewer reconnections; and final site restoration, including surface paving, pavement markings, permanent signing and posts, sidewalks, curbs, driveways, curb ramps, planting, and landscape establishment.

The purpose of the Work at the Sylvan Site is to provide water quality treatment for street runoff that drains to Longfellow Creek by retrofitting the roadside with bioretention treatment system. This portion of the Project consists of the following elements of Work including but not limited to: construction stormwater erosion control (submittal, implementation, and maintenance of the Construction Stormwater Pollution Prevention plans (CSECP/SWPPP, TVSPP, SP, and TDP)); health and safety plan; clearing and grubbing; demolition and removal of existing surface pavement and curbs; potholing; excavation; temporary traffic control plan and implementation, including flagging; site preparation and staging; survey; removal and abandoning existing drainage structures and piping; well decommissioning; temporary shoring and dewatering; temporary stormwater bypass; protection, relocation, and/or adjustments of existing utilities; reconnection to the existing drainage system; installation of new surface drainage systems, including: storm drainage piping, drainage structures, and bioretention cell; gutter flow testing; television inspections; and final site restoration, including: surface paving, curbs, soil amendments, planting, landscaping and establishment.

The purpose of the Work at the NE 137 ^th Headwall site is to improve debris collection as well as to reduce erosion and sedimentation that threatens the roadway embankment, neighboring properties, and fish habitat. This portion of the Project consists of the following elements of Work including but not limited to: construction stormwater erosion control (submittal, implementation, and maintenance of the Construction Stormwater Pollution Prevention plans (CSECP, TVSPP, SP, and TDP)); health and safety plan; clearing and grubbing; potholing; excavation; temporary traffic control plan and implementation including flagging; site preparation and staging; survey; temporary stream bypass; installation of a steel soldier pile headwall with concrete panels and a new trashrack at the upstream end a 36-inch-diameter concrete culvert beneath the roadway; removal and re-installation of existing guardrail as necessary to do the work; new guardrail; and site restoration and planting.

Engineer's Estimate: $3,737,500

Project Location: This Project is located at 3 distinct sites within the City of Seattle:

1. The Broadview Site includes 2 locations in the Broadview neighborhood: 1) Along NW 130th St between 1st Ave NW and 3rd Ave NW and 2) Along NW 127th Street from 3rd Ave NW and then south along 1st Ave NW.

1. The Sylvan Site is located at the Sylvan Way SW and SW Orchard St intersection which is within the Longfellow Creek basin.

1. The NE 137 ^th St Culvert Headwall Site is located on NE 137 ^th Street between 30 ^th Ave NE and 32 ^nd Ave NE.