City Commissioners approved a $446,462 agreement with Advanced Engineering and Environmental Services for the water treatment plant sedimentation basin upgrade during their April 1 meeting.

Under the agreement, AE2S will design, facilitate bidding, provide construction administration and complete as-built drawings and certification documents for the project, which is scheduled to begin construction in early 2026, according to the city.

The water treatment plant treats surface water from the Missouri River via a conventional flocculation, sedimentation, filtration and disinfection treatment process, according to city public works.

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Five settling basins help with many aspects of water treatment including the removal of solids, separation of suspended particles and the overall improvement of water quality prior to treatment.

The current mechanical chain and skid system was built in the 1930s and utilizes a steel system of chains and pulleys to remove the sediment and staff are estimating a major basin failure within three years due to its age, design, volume or failing components and inability to divert from basins during peak flow, according to public works.

The main portion of the proposed project will remove and replace dated mechanical settling components within two existing basins, that all operate near or at capacity depending on demand leaving minimal options for diversion capability if there was a mechanical failure, according to staff.

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Under the agreement, AE2S will evaluate the ability to install and retrofit the system with a new system consisting of modern stainless steel equipment within two existing basins, plus the up and downstream fitment of the new system, according to city staff.

New equipment offers better reliability, improved solids removal, lower maintenance and operation costs, and can reduce turbidity of the water entering the filter section, which could reduce maintenance and lifecycle costs of downstream equipment over the long term, according to public works.

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Current capacity projections estimate that two basins updated with modern equipment can manage the same as the settling capacity as all five existing basins, allowing staff to keep the other three basins for reserves, future growth capacity or other needs, according to staff.

The project has been prioritized through a risk maintenance based on excess wear found during routine maintenance.

The project will be funded through available water enterprise funds.

If commissioners opt to delay the project, “it would result in reaching critical capacity, and the risk of emergency repair that is estimated to cost $1,000,000 per basin with service disruptions during peak season,” according to public works.