COMBINED SEWER OVERFLOWS

In 1994 the United States Environmental Protection Agency published new regulations for communities and sewage treatment plants that have sewer lines that take in sanitary sewage and storm water. In the Kiski Valley area there were 31 combined sewer outfalls. These outfalls discharged rain water and sewage to the Kiski River during moderate to severe wet weather events.


The Kiski Authority was required by the PA Department of Environmental Protection to prepare a long Range CSO (Combined Sewer Overflow) Control Plan. The Authority selected the EPA CSO Control Policy "presumption" approach criteria ii through their Long Term Control Plan (LTCP) requiring elimination or capture for treatment of no less than 85% by volume of combined sewage collected in the CSS (Combined Sewer System) during precipitation events. Through sewer separation and upgrade projects in tributary communities the number of diversion outfalls has been reduced to two (2) currently thus increasing the volume of collected sewage and reducing the volume of stormwater treated at the treatment plant. Additionally, the Plant Expansion Project has provided the necessary additional capacity to meet the EPA requirements.


COMBINED SEWER OVERFLOWS


During wet weather conditions (rain, melting snow) , the combined flow of sewage and storm water was too great for the existing sewer lines to carry the flow to the KVWPCA plant for treatment. The excess flow was diverted directly to the river through the 31 diversion chambers located along the Kiski River. The flow was diverted by the diversion chambers then discharged to the river through Combined Sewer Outfalls. These Diversion Sewer Outfalls (2 remaining) are identified by Combined Sewer Overflow signs located in the Vandergrift area.

Combined Sewer Overflow Sign

Combined Sewer Overflow Diversion Chamber

Combined Sewer Overflow Outfall