Seattle Public Utilities Mami Hara, General Manager/CEO

Broadview Sewer & Drainage Improvements


We’ll be making sewer and drainage improvements in Broadview neighborhood.

What & Why

What’s happening now?

The Broadview neighborhood has longstanding sewer and drainage problems. During heavy rains, water can overwhelm Broadview’s sewer system and cause sewage backups into homes, which is a serious public health issue. Stormwater runoff can also flow from streets onto private property and cause damage. Broadview’s high water table, steep bluff, lack of consistent drainage and aging sewer pipes contribute to the complexity of these issues.

Since 2012, Seattle Public Utilities has been working with the community to identify sewer and drainage projects in the areas of Broadview that are most impacted. The project team completed a detailed analysis and recommended preferred options.

Proposed 12th Avenue NW drainage improvement project

This project will improve drainage in the 12th Avenue NW drainage system (pdf), along 11th Avenue NW between 120th and 122nd streets. It will reduce storm-related flooding by slowing runoff and improving flows, and its design will allow for future drainage work upstream of the project area. The project will:

  • Convert ditch-and-culvert flow to a piped system along 11th Avenue NW between NW 120th and NW 122nd streets
  • Install large, underground pipes to hold water and prevent flooding during storms
  • Install rain gardens and bioretention in several locations

Estimated budget: $4.9 million

Proposed Dayton Avenue N sewer improvement project

Stormwater that enters sewer pipes is the main cause of sewer backups in the Dayton Ave N area (pdf). To reduce sewer backups, this project will:

  • Fix leaks in mainline sewer and in up to 150 side sewers along Phinney Avenue N and Dayton Avenue N between NW 115th and NW 125th streets
  • Improve sewer line flow by increasing the size of mainline pipes along Phinney Avenue N and Dayton Avenue N
  • Remove stormwater flows from the sanitary sewer by disconnecting private sump pumps, foundation drains and downspouts and re-connecting them to new drainage features
  • Add new drainage features like rain gardens to manage stormwater kept out of the pipes

Estimated budget: $13.7 million

Learn more about how these projects were selected for the Broadview Sewer and Drainage Improvement Program (pdf).

Project goals and benefits

The overall project goal is to reduce the potential for sewer backups and surface flooding for the Broadview neighborhood.


Grace Manzano, project manager
(206) 233-1534

Sign up for Broadview project updates