Woodward Water Treatment Plant
- Economic Development
- Public Utilities
- Potable Water
- Xenia, Iowa
Xenia Rural Water District needed upgrades to its Woodward Water Treatment Plant (WTP), originally constructed in 1983. The plant is a conventional lime softening plant with two shallow alluvial wells for source water.
The treatment process generally includes a single upflow clarifier and two gravity filter cells. In addition to lime, polyaluminated chloride (PAC) is added upstream of the clarifier to reduce solids carryover. The filtration process consists of two steel filter cells. The existing filter backwash process utilized a single backwash pump with rotating surface washers. All valves and controls were manual. Backwashes were commonly conducted once per day, requiring significant operator attention.
Before the Woodward Water Treatment Plant design, a facility evaluation was completed to evaluate rehabilitation needs and alternatives for improving the removal of excess raw water ammonia and performance improvements to the recarbonation process. The following water treatment plant improvements were designed after the evaluation.
- Implementation of a side stream breakpoint chlorination system to remove excess raw water ammonia while maintaining adequate residual ammonia for the formation of chloramines.
- Replacement of the lime bin dust collector, hydrated lime feeder, and mixing tank. In addition, a full base cone vibrator was installed on the existing lime silo.
- Full replacement of the solids contact clarifier equipment, including a new access bridge.
- Various improvements to the two-cell gravity filter system.
- Replacement of all chemical storage and feed equipment, including the implementation of a non-proprietary carbon dioxide solution feed system.
- Replacement of all water quality instrumentation, including pH probes, chlorine analyzers, and turbidimeters.
- Replacement of all water treatment plant controls and SCADA system.
- Replacement of all electrical power systems.
- Addition of a stationary backup power generator, including an automatic transfer switch.
- Improvements to address corrosion problems associated with the humidity created from the open basins. The improvements included recoating existing piping, filter boxes, and structural steel. Concrete containment curbs were installed near the filter area to protect the existing steel siding. Improvements to the ventilation system to protect new electrical equipment and the installation of a Tnemec Aerolon insulating coating system on the exterior of the steel filter boxes were made.