The City of Rushville, Indiana, had to remedy a consent order filed in 2007 for its untreated combined sewer overflow discharges that were polluting the Flatrock River, a violation of the Clean Water Act. The city originally planned to install a 1 mgd stormwater storage tank, but was approached by Aqua-Aerobic representatives with a pilot test proposal utilizing a new technology. The pilot proposal featured the AquaStorm Cloth Media Filter utilizing 5-micron microfiber cloth media, which would be tested during five wet-weather events. This study captured events from May-July 2015, and produced impressive results. The successful pilot test prompted the city to request a design for an AquaStorm filtration system in February 2016. The request came with two stipulations: the filters were to treat both dry and wet weather conditions, and alum coagulant was to be injected upstream of the filters to meet future effluent phosphorus limits and eliminate fine CSO particles.

The AquaStorm filters were retrofitted into the plant’s existing, abandoned sand media filter structures, saving the city considerable capital costs. In addition, the new filtration system was $1 million less than the original conventional storage tank design.

The AquaStorm cloth media filters experienced the first wet-weather events shortly after startup in October and November 2017. Due to the continuous treatment capacity, no untreated overflows have occurred.