Project Details

A new 17 MGD intake screen was installed to replace WEB's existing 8 MGD screen. The new screen was a copper-nickel-coated stainless steel screen designed to resist zebra mussel growth while maintaining structural integrity. Two redundant 2" HDPE chemical feed lines were installed inside the existing intake pipe from the building to the screen. The feed lines will be connected to a future chemical feed system, which will deliver chemicals throughout the intake infrastructure to protect against zebra mussel growth in the upstream infrastructure, including the intake pipe, raw water pumps, raw water pipeline, and water treatment plant.

This project represented several unique challenges. First, work was occurring in a major public waterway, which required additional coordination with regulatory agencies, including the Army Corps of Engineers. Additionally, zebra mussel mitigation was relatively new in South Dakota; Banner worked closely with state agencies during design to ensure that it met anticipated requirements and best practices. Furthermore, incomplete records of the original construction required an additional specialized sonar survey work and remotely operated vehicle (ROV) intake pipe inspection during the design phase. Finally, construction 70 ft underwater and over 1,000 feet offshore required specialized equipment and crews, including barges and divers.

This project benefited the client by providing additional raw water supply for WEB, which, in conjunction with other improvements throughout their system, will allow them to meet the growing demands of existing customers, eliminate moratoriums, and better serve new customers. Additionally, it set up WEB's system to respond proactively to the looming threat of zebra mussels. Finally, combining the two objectives into one project saved on overall construction costs.

For this project, we provided: