Nestled in the Little Ozark region of southeast Kansas, the City of Fort Scott serves a growing population of more than 8,000 area residents. The goal of serving its residents directed Fort Scott leaders to determine the best solutions to the City’s wastewater needs with the least amount of environmental and financial impacts.

Flood proofing, innovative design for meeting NPDES water quality standards and capitalizing on multiple funding opportunities were the driving forces in the success of the Fort Scott Wastewater Treatment Plant Improvements project.

The State of Kansas passed new water quality standards that required Fort Scott to install disinfection equipment, control ammonia levels in wastewater and provide additional flood protection for the wastewater treatment facility.

Fort Scott combined four funding resources to construct the wastewater treatment facility improvements that fulfilled these requirements and provided for future population projections and regulations.

Flood Prevention
Fort Scott has seen its share of flooding, with four 100-year floods since 1986. Each time the City floods, the treatment plant has been under water. The flooding caused silt and sludge to deposit in the lagoon system. Efforts such as dredging the lagoon and building up the aerator system did not prevent deposits.

To keep floodwaters from overflowing into the wastewater plant, the dike around the plant was extended 2-1/2 feet to an elevation of 805.5 feet providing protection against a 500-year storm. The dike encompasses all the new structures, as well as the existing Operations Building and existing lagoon. The lagoon was included in the flood protection measures so it could be used for extraneous flow treatment. As a funding partner, the Federal Emergency Management Agency (FEMA) monitored the flood proofing construction efforts.

The existing wastewater facility was designed for an average daily flow of 3.0 MGD. This suffices for population projections through the year 2040. The new facility improvements allow the facility to accommodate short peak flows of up to 30.0 MGD. These flows are screened and routed to the lagoons for extraneous flow holding. The flow is returned to the plant for treatment during periods of low flow.

This process saves the City a substantial amount of money because property acquisition was not required and further encroachment into the floodplain was not mandated. This plan also simplified the permitting process.

Treatment Improvements
The treatment modifications equip the existing facility with a new headworks building, new activated sludge system (Raw Activated Sludge-RAS and Waste Activated Sludge-WAS), ultraviolet disinfection and sludge processing.

The new headworks building includes a barscreen/screening compactor, a grit removal system and dewatering unit, with extraneous flow diversion. The headworks building also houses the sludge pump station, disinfection and maintenance shop in a single building.

The sludge pump equipment consists of RAS and WAS pumps, digester blowers, digester pumps, and sludge loadout pumps. Medium pressure ultraviolet disinfection was installed to allow the facility to comply with disinfection requirements on the Marmaton River. The Marmaton River provides a home for several endangered species and UV disinfection treatment of the plant effluent poses no further threat to their fragile environment.

The aeration basin consists of several integral basins to achieve total nitrogen removal and biological phosphorus removal. Although total nitrogen and phosphorus are not yet required under current permitting, it was included to encompass anticipated future regulatory demands. The facility includes anaerobic basins, anoxic basins and aeration basins.

The aerobic digester is sized for 40 days and the aerated holding basin contains 60 days of sludge storage as required by KDHE. Other improvements include modifications to the existing administration facilities and two major pump stations. All telemetry and computer controls were replaced and all upgrades to facility operation comply with recording requirements.

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