2016 “PROJECT OF THE YEAR” AWARD WINNER - THE ELM RIVER INTAKE PROJECT
A city’s water source is arguably the most important factor in its sustainability, health, and long term welfare. A water treatment plant is an important investment for a city, and maintaining its good condition is a top priority. When the City of Aberdeen, South Dakota decided to address recurring problems with their water treatment plant (WTP) intake structure, they faced having to move its drinking water intake downstream on the Elm River. Larger rainfall events since 1997 meant more sedimentation near the water intake- the river’s natural processes had accelerated. Clark Engineering and Wenck partnered to produce a truly innovative and economical solution that transformed the way the city receives its water.
Aberdeen was experiencing ongoing problems with water quality and quantity due to three major issues: sediment transport and deposition at the water treatment plant intake, potential loss of their water supply due to erosion and scour of the narrow land bridge forming the peninsula of the oxbow, and stabilization of the shoreline next to the WTP due to erosion during high flows. The city had attempted several fixes over the years without any long term success. The Elm River Intake Project addressed all these problems with an original and innovative design, and now provides a long term economical solution for the city.
The Elm River Intake Project required the design of an entirely new section of river channel to replace the oxbow that was intentionally cut off from the river. A rock filter berm was constructed across the oxbow to serve two purposes; it allowed water to flow laterally through the rock berm to provide water to the WTP intake and it served as the south bank of the new section of river channel. This allowed high sediment flows to remain in the main channel of the river and bypass the area of the intake. The oxbow was mechanically dredged to increase the storage volume and remove accumulated sediment from the area of the intake. Wetlands were constructed to mitigate impacts from construction of the rock filter berm, including endangered species issues, in a creative design utilizing the isolated peninsula within the oxbow.
Through these innovative concepts designed specifically to address Elm River’s challenges, the city was able to avoid costly relocation and construction of a new intake and correct the on-going problems which threatened their existing site. It was constructed without interrupting water service to the 26,000 residents of Aberdeen, and allowed the city to continue utilizing existing facilities in which they have a long term investment. Building upon that community investment, the project was bid and awarded to a local contractor supporting businesses within the surrounding area. In fact, Clark Engineering’s Aberdeen office did much of the design working hand in hand developing Wenck’s creative solutions to save the city over a million dollars. The project was financed through the SD State Revolving Fund and City of Aberdeen.
The combination of Wenck’s expertise in big river mechanics, hydrologic and hydraulic modeling, fisheries and wetland biology partnered with Clark Engineering’s award-winning design were critical to successfully working through all the aspects of this project including the threatened and endangered species and wetland permitting. The City of Aberdeen has truly been transformed in the way they receive their water and maintain the sustainability and overall well-being of their community.