Water System Flushing Begins
March 16, 2007
Pipe Cleaning Program Improves Water Quality
Madison-Madison Water Utility will start its annual water main cleaning program on Sunday night, March 25 and Monday morning, March 26, weather permitting. The cleaning operation will scour and eliminate mineral sediments, such as iron and manganese, which accumulate in the pipes over time and which can cause colored water to reach customers' taps under certain circumstances. This year's pipe flushing program is expected to proceed until the end of November.
In the fall of 2005, the Utility piloted a new process called "unidirectional flushing" to clean 30 miles of water mains on Madison's near west and south sides. The new process involves closing valves and opening fire hydrants in a pre-planned, specified sequence in order to direct high velocity water flow through targeted sections of pipe to maximize scouring effectiveness. The traditional flushing process involved opening and flowing hydrants, but without regard to directing and maximizing flow velocities.
The Utility used unidirectional flushing in 2006 to clean approximately 50% of the city's 840 miles of water mains, while using traditional flushing methods throughout the rest of the city. Water quality testing was done before, during and after flushing, and the results showed that the unidirectional flushing process significantly lowered iron and manganese levels in the water mains. Over 2000 tap water samples were taken at customers' homes. Over 91% were below the federal guidelines for aesthetics, and no test sites were found to be consistently over the federal lifetime health advisory level for manganese.
In 2007, the Utility is planning to use unidirectional flushing to clean all 840 miles of water mains in the City. Utility officials expect the new process to significantly reduce the occurrences of discolored water being drawn into customers' homes and businesses and to alleviate elevated iron and manganese levels found in some parts of its distribution system.
"Our experience has been consistent with recent national research studies and the experience of other water utilities across the country, which shows this method of cleaning water systems to be far more effective than traditional flushing programs," said General Manager David Denig-Chakroff. "In 2006, unidirectional flushing removed much of the manganese and other material from our mains and we believe it will continue to be a key element in managing water quality issues," said Denig-Chakroff.
Unidirectional flushing is more labor intensive and time consuming than the utility's traditional flushing program. The utility has budgeted $400,000 for the unidirectional flushing program in 2007, which is an increase of $345,000 over the cost of the utility's traditional flushing program.
Under the new program, utility crews will be scheduled to flush water mains Monday-Friday, 7:30 a.m. to 3:30 p.m. for about eight months. One crew will work at night Sunday-Thursday from 10:00 p.m. to 6:00 a.m. around the Capitol Square, University, and some other areas where flushing at night may minimize impact on customers. "If customers use water during the 20 to 60 minutes crews are flushing the pipe on their street, they may see discolored water at the tap," said utility chief engineer Al Larson.
• Discolored water should not be used for drinking or cooking since it may contain unusually high levels of manganese and other minerals.
• Washing clothes in discolored water may cause laundry stains.
If customers experience discolored water during the operation, Larson advises opening the cold, hard water taps nearest to the water meter to full flow until the water runs clear. If discolored water persists, customers should contact the water utility at 266-4661.
The location of flushing crews during any given week can be obtained by visiting the utility's website at www.madisonwater.org or by calling the Flushing Hotline at 261-9178 to hear a pre-recorded message. In addition, areas scheduled for flushing will be published in major local newspapers the first Monday of each month. Customers may also request to be added to a list for email notification of flushing locations by contacting the utility by email at firstname.lastname@example.org or by phone at 266-4651.
In addition to the new more effective flushing program, the utility is taking other steps to improve water quality, including:
• Reducing, to the extent possible, the use of wells that produce elevated levels of manganese.
• Investigating the feasibility of installing filtration or replacing wells where reduced pumping is not an option.
• Replacing substandard water mains that may be causing build-up of mineral sediments in the system.
• Continuing comprehensive water quality monitoring studies jointly with the Department of Public Health for Madison and Dane County.
"The new flushing program is a key component to the City's plan for protecting and improving the quality of our drinking water," says Mayor Dave Cieslewicz. "We are blessed with an abundant, high quality source of drinking water, and I'm encouraged by the work of the Water Utility and Health departments to protect this vital public resource."
- David Denig-Chakroff, General Manager, 266-4652
- Doug De Master, Flushing Coordinator, 261-9834