Assessing the Effectiveness of a Storm Water Basin to Eliminate Wastewater Overflows

Abstract

Wastewater treatment facilities are an important part of any urban community because they help decrease the amount of wastes entering waterways from homes and businesses. Yet due to increased flow associated with changes in population density and storm intensity, many wastewater treatment systems are becoming obsolete, frequently having no other option than to push untreated water into open waterways. This causes problems because the high levels of phosphorus in wastewater can alter aquatic ecosystems by causing algal blooms, and high levels of fecal coliform can ultimately contaminate the drinking water supply. One option of wastewater treatment plants is to use a storm water basin to collect and store excess inflow of wastewater until it can be treated by the plant. This would essentially increase the flow capacity of the plant without having to rebuild the existing wastewater facility. However, the effectiveness of this method remains unclear, and so the purpose of this study was to examine the efficiency of the storm water basin at the Wastewater Treatment Facility in Kenosha, WI (KWWTF). If the storm water basin at KWWTF is effective, then we would expect to see fewer instances of overflow when the basin is in use, as well as effluent phosphorus levels that meet EPA standards of less than 1ppm. To address this hypothesis, data were collected from 2006-2009, including total amount flowing through the plant, the number of pumps used (which is an indicator of the use of the basin), the total phosphorus and suspended solids in the effluent and the amount of wastewater released by overflows to Lake Michigan. It was found that when there were extremely high flows; more pumps were utilized, thus causing the basin to be used. It was also found that the basin was not 100% effective in eliminating the overflows, likely due to the patterns of rainfall. The basin utilized by the KWWTF, may reduce the number of annual overflows, but may not 100% eliminate them when storms intensify.