Iowa Department of Natural Resources Environmental Services Division For Immediate Release May 24, 2007 HEAVY RAINS LEAD TO WASTEWATER BYPASSES MEDIA CONTACTS: Kirk Mathis at (712) 243-1934. DES MOINES -- Heavy rains Wednesday evening and into Thursday overloaded wastewater treatment systems throughout southwest Iowa, leading to a number of wastewater overflows. Heavy rain can overload wastewater collection systems, which are the underground sewer pipes that carry sewage to a treatment plant. With the sewage pipes overwhelmed, the excess water has nowhere to go, and can backup into basements through floor drains. Bypassing can lower the water level in the collection system, keeping sewage from backing up into basements, which would present greater and more immediate health risks than discharging wastewater into a stream. These types of situations can occur when large amounts of rainwater or snowmelt, also called storm water, enter a sanitary sewer from cracks in sewer pipes, or improper connections, such as roof drains or sump pumps hooked up to the sanitary sewer system instead of the storm water system. The storm water should enter the storm sewer system, which receives no treatment before entering a stream or lake. Instead, storm water enters the sanitary sewer system (which treats wastewater from homes and businesses). In addition, some communities use equalization basins or storage ponds to handle excess flow from large rain events. These basins hold incoming wastewater until the plant catches up and can treat it. However, in extremely heavy rain events, some facilities must discharge from these basins and ponds to maintain their structural integrity or to prevent the plant from flooding. Other times, lagoons used for treatment can fill up quickly from increased flow and rainfall, and must discharge to maintain their structural integrity. According to DNR design standards for construction of new wastewater treatment systems, facilities should be able to handle the amount of water in the collection system from all three of these events happening at the same time: * Peak sewage flows from homes, businesses and industry * Peak groundwater levels * A storm that drops two inches of water in an hour. While many collection systems in Iowa already have or are in the process of upgrading their collection systems to handle these events, many more need to upgrade. The DNR tracks bypass reports submitted by facilities and follows up with the facility to determine problems and help them upgrade their systems, although it can be a long-term process. The DNR has also formed a committee to discuss how it handles wet weather bypasses. Adair County Adair: The City of Adair began discharging untreated wastewater from its treatment plant and a lift station to the Middle River early Thursday. The city will monitor the ongoing bypass. Greenfield: The City of Greenfield began discharging untreated wastewater from the equalization basin at its treatment plant to the Thompson River at 8 a.m. Thursday. The basin is full and overflowing due to heavy rainfall. The city's wastewater operator will monitor the ongoing bypass. Stuart: The City of Stuart's wastewater treatment plant was unable to keep up with excess flows following heavy rains, leading it to begin discharging wastewater early Thursday morning. Some wastewater is receiving partial treatment before it is discharged to Long Branch Creek; other wastewater is discharging directly to the creek without treatment. The partially treated wastewater is discharging at a rate of 160,000 gallons per day, while the untreated wastewater is discharging at a rate 80,000 gallons per day. The city estimates the bypass may last for six to seven days, and is monitoring the situation. Officials at Diamondhead Lake have been notified of the bypass. Cass County Cumberland: The City of Cumberland's lift station could not keep up with heavy rainfall, leading the city to discharge untreated wastewater at a rate of 200,000 gallons per day. The bypass began around 6 a.m. Thursday and is discharging to Hoyt's Branch, which flows to Seven Mile Creek. The city's wastewater operator will monitor the ongoing bypass. Guthrie County Guthrie Center: The City of Guthrie Center began discharging untreated wastewater from a lift station at 8:45 a.m. Thursday to prevent sewer backups into basements following intense rains. The wastewater is discharged to a drainage ditch that leads to the South Raccoon River. The city's wastewater operator will monitor the ongoing bypass. The Des Moines Water Works has been notified of the bypass. Montgomery County Red Oak: Untreated wastewater is discharging from two manholes in Red Oak to the East Nishnabotna River. The discharge began at 6 a.m. Thursday to relieve pressure on the sanitary sewer and prevent sewage from backing up into basements. The city will monitor the ongoing bypass. Stanton: The City of Stanton began discharging untreated wastewater from its main lift station to the Tarkio River at 9:30 p.m. Wednesday. The lift station could not keep up with heavy rainfall. The city is discharging wastewater at a rate of 130,000 gallons per day. The city's wastewater operator will take water samples and continue to monitor the ongoing bypass. -30- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - To unsubscribe from the IOWA-TOPICS list, send any message to: [log in to unmask] Check out our Listserv Lists support site for more information: http://www.sierraclub.org/lists/faq.asp