What’s the plan?

PWSA is evaluating two techniques for connecting the restored Four Mile Run to the Monongahela River. The first technique is for a potential stream connection parallel to Boundary St, Saline St, and Greenfield Ave. The second technique is for a potential stormwater tunnel deep under South Oakland and Second Avenue.
This connection will potentially enable rainwater from Squirrel Hill, Oakland, Greenfield, and Schenley Park to flow to the Monongahela without entering the combined sewer system.

How is this being designed?

The design and engineering team must evaluate several variables to see which of the two connection techniques works the best. In either scenario, the team is seeking to minimize flooding and combined sewer overflows.

  • The open stream and shallow culvert along Boundary St, Saline St, and Greenfield Ave would be placed within or adjacent to the existing street and would need to avoid or possibly relocate some existing buried utilities. Within existing open spaces, the stream would be open and clearly visible. In other places it would flow inside in a large box culvert or pipe. The lack of steep drop-offs and a more open channel would promote ecological connectivity between the Monongahela River and Panther Hollow making Four Mile Run visible for most of the way to the Monongahela River.
  • The potential tunnel connection under South Oakland would require a drop shaft near the existing parking lot to bring the water to a lower elevation. The tunnel would be very deep under the neighborhood and a specific path for a potential tunnel has not yet been determined. This would allow rainwater to flow to the river while bypassing the Four Mile Run neighborhood and avoiding most utilities.