Puget Sound Beach CSO Projects

View CSO control options poster (PDF, 85 KB).

Option

Description

Key Considerations

Click image to view larger version

1

Store peak flows during large storms and send to the existing treatment plant after the storm.

• All flow is sent to the existing West Point Treatment Plant or the Carkeek and Alki Storm Weather Plants for treatment

• Technology is proven and reliable

• Finished facility is primarily underground and attractively landscaped

• Sufficient space required for siting and constructing the facility

• Heavy equipment needed during construction

Store Peak Flows
(pdf, 186 KB)

2

Increase pumping and conveyance to direct peak flows to existing treatment facilities.

• All flow is sent to existing plants for treatment

• Construction is required over a much broader area

• Need to assure that problem is not shifted to a different downstream location

• Sufficient space required for new or expanded facilities

Increase Pumping and Conveyance Capacity
(pdf, 119 KB)

3

Reduce peak flows of storm water and ground water into the combined sewer system.

• Low-tech, “green” solutions to CSOs

• Reducing storm water flow gets at the root of the CSO problem

• Peak flows into the combined system during storms are reduced, minimizing the need for other capital improvements

• Storm water must be managed in other ways, such as bioswales

• Extensive property owner participation is essential

• Confirming sources and locations of storm water connections can be difficult

• Numerous agreements with government agencies and private property owners are required

Reduce Peak Flows of Storm Water and Ground Water into the Sewer System
(pdf, 91 KB)

4

Treat peak flows at a new local treatment facility.

• Facility serves a local area

• High-rate process provides treatment in small footprint

• Sufficient space is required in vicinity of an outfall

• Permitting requirements for facility can be rigorous

Treat Peak Flows
(pdf, 199 KB)

5

Use combinations of the options.