Water Resources

Cass Adams Relief Sewer

The City of Evansville began implementing an Integrated Overflow Control Plan (IOCP) program—the largest public works project in the city’s history. One major control measure was the restoration of Bee Slough, a large open concrete-lined swale conveying most of Evansville’s combined sewer overflows (CSOs). The Cass Adams Relief Sewer was intended to provide 100% CSO control. New drains direct CSO flow to the East Wastewater Treatment Plant through 5,000 feet of 60-inch relief sewer and a dewatering pump station. The project was constructed within a very limited corridor due to adjacent Bee Slough facilities and a residential neighborhood, which required precautions to not adversely impact residents.

The sewer is maintained by a large curvilinear retaining wall that mimics the neighboring Ohio River. The wall is stained bronze and adorned with architectural revels and lighting. The beautification of the wall coalesces with the incorporation of planning for a future multi-use trail along the sewer alignment. Additionally, this project was coordinated with Keep Evansville Beautiful to plant 228 trees downtown to mitigate trees lost due to construction and assist in rebuilding the tree canopy. In remedying CSOs while beautifying the area, this investment in placemaking signifies the city’s commitment to using the IOCP for more than just water quality mitigation.

Project summary


The relief sewer provides 100% CSO control within Bee Slough in Evansville, Indiana.

5K ft.

5,000 feet of 60-inch relief sewer carrying CSO to the East Wastewater Treatment Plant.


228 trees planted downtown in coordination with Keep Evansville Beautiful.

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Andrew Scales, PE*

Andrew Scales, PE*
Vice President, Business Practice Leader, Principal Engineer

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Andrew has over two decades of experience in planning, modeling, design, permitting, and construction for water, wastewater, and stormwater projects. He excels in public engagement for sensitive infrastructure matters, client relations, regulatory compliance, and field crew management. Andrew is also highly skilled in project scheduling, resource management, and sustainable land development.