WWTP Expansion & Improvements

Growth in Decatur’s service area caused increased flows. The flows exceeded the capacity of the headworks, influent pump station, and effluent conveyance systems. The plant is approaching its design capacity. Opportunities need to be examined to improve reliability and resilience. These must be prioritized and balanced with available funding. Because of these complexities, the City chose a progressive design-build project. The team includes Crossland Heavy Contractors and Allgeier Martin (AMA).

AMA’s primary objective is to design improvements for Decatur’s wastewater treatment plant. AMA’s design includes new headworks with screening and grit removal with redundancy. The headworks firm capacity is up to 24 MGD. The hydraulics of the headworks will better divert to and use existing storage. The improvements also include a new influent pump station. The new pump station has more capacity, process control, and reliability. The design follows Hydraulic Institute Standards. It has a deeper wet well and baffles to reduce solids and air issues. It also has better flow to pumps, quick pump swap provisions, and direct feed from each pump to a specific train. It can also automatically reassign pumps between trains.

The project will improve effluent conveyance. This will increase the effluent capacity, re-aeration via cascade aeration, and flow measurement capacity. To improve peripheral systems, the design includes a new plant recycle pump station. This affords increased reliability and capacity. It involves a new water pressure system. The system is for non-drinking water. It will feed improved headworks and increase the use of plant effluent as plant service water.