About the Project

What was the Issue in Ault Park?

During heavy rains, raw sewage—mixed with stormwater—overflowed from a combined sewer in Ault Park into adjacent Duck Creek.

The combined sewer ran beneath the bed of the Valley Trail stream (see map). There were stormwater inlets along the length of the creek. When it rained, stormwater entered the combined sewer through the inlets instead of flowing naturally down the hillside to Duck Creek.

When large volumes of stormwater entered the combined sewer, it filled beyond its capacity and overflowed into Duck Creek through Combined Sewer Overflow (CSO) 503. About 20 million gallons overflowed annually, causing odors and leaving behind unsightly debris. Combined sewage also surcharged back into the creek bed.

What was the Solution in Ault Park?

MSD partnered with the Cincinnati Park Board and Hamilton County Soil & Water Conservation District to implement a unique solution—the first of its kind in Hamilton County—to eliminate 85% or 17 million gallons a year of overflows from CSO 503 into Duck Creek.

MSD restored—or daylighted—the creek so it could receive and handle flows after rainstorms and snow melts and transport the stormwater directly to Duck Creek. This solution reduces sewer overflows by reducing the amount of stormwater entering the combined sewer.

The creek was restored through streambank stabilization and the addition of natural stream features such as log and rock drop structures to regulate the flow and speed of the stream. Streambank stabilization included the planting of native riparian species such as sedges and wildflowers, replacement of trees that were removed in a (3:1 ratio) and other activity to restore the creek bed and prevent erosion. This restoration work also helped improve aquatic habitat.

The project also included:

• Closing nine stormwater inlets along the creek so the flow can no longer enter the combined sewer.


• Installing a 60-inch-diameter dedicated underground storm sewer culvert beneath Observatory Avenue in Ault Park (in the vicinity of the pull-off for the Valley Trail) to address stormwater flows that begin on the west side of the road. The underground pipe connects to the restored creek on the east side of the road.


• Installing a special valve at CSO 503 to close off the connection between Duck Creek and the combined sewer to prevent the creek from backing up into the sewer. The combined sewer will remain in place and continue to carry sanitary sewage flows (and a much smaller amount of stormwater runoff) to the Little Miami Wastewater Treatment Plant in the East End.

The project starts at manhole 42404024 on the west side of Observatory Avenue (roughly across the street from the pull-off for the Valley Trail) and ends at CSO 503 at Duck Creek near Old Red Bank Road.