Archive for November, 2013November 20, 2013
Finding leaks early helps reduce the level of damage that a larger main break might cause. Leak detection also helps keep production costs down, which in turn has a positive impact on our customer’s water rates.
DMWW began its leak detection program in 1983. At the start of the program, DMWW’s unaccounted for water (total pumpage minus billed) was at 15 percent. Today, DMWW’s unaccounted for water is 7-9 percent.
Water Distribution’s staff performs an annual leak survey of the distribution system. In addition, leak survey and follow-up activities are conducted for other metro area communities, plumbers, contractors and property owners.
The leak detection team uses a highly sensitive electronic sounding device to listen for leaks. The leak surveyor systematically works his or her way through the distribution system sounding valves, blow-offs and hydrants, searching for leaks. When a leak sound is discovered, the leak surveyor records the leak in DMWW’s geographic information system (GIS) software. These leaks can be as small as pinholes in the pipe or as large as a split main.
Follow-up involves sounding the structures where a leak sound was found during the survey. The Field Service Technician must determine if the leak is actually on the valve, hydrant, or the main. A leak correlator and outstation sensors are used to run scans on the water main to pinpoint the location of a leak. The leak can usually be pinpointed within one to two feet of its actual location. Identified leaks are then turned over to a repair crew.
Advance pinpointing of leaks and main breaks saves Des Moines Water Works $30,000 to $50,000 each year in labor costs.
As cold weather draws near, water main breaks become more common. The months of December, January and February bring the highest number of water main breaks. Des Moines Water Works crews repair an average of 300 water main breaks each year. Although DMWW has a proactive and aggressive main replacement program, underground water mains can break for a number of reasons including corrosion, frost heave, and pressure fluctuations.
When a water main breaks, generally water comes to the surface and flows across the ground to a storm sewer or waterway. Large water main breaks can reduce water pressure in the area and the flowing water can cause damage. If you witness a main break or see water flowing in the street, please call Des Moines Water Works at 283-8772. Des Moines Water Works is committed to providing our customers with safe, quality drinking water. To honor that commitment, Des Moines Water Works crews are on call 24 hours a day, 365 days a year to respond to main breaks, ensuring that your service is restored as quickly as possible.
Once a water main break has been confirmed, the exact location of the break is determined using acoustic leak detection equipment. This equipment listens to the sound the water makes as it exits the pipe and can determine the location of the leak based on the intensity of the sound. When the location of the leak has been determined, water service in the area must be shut down so the break can be repaired. Depending on the time of day and the extent of the outage, it may not be possible to notify customers before the water is shut off. The safety of our employees and the public during a main break repair is a top priority. Special attention is given to trench safety which protects our employees and to traffic control which protects our employees as well as the traveling public. Before the water service is restored, the repaired water main is flushed and sampled to restore the best possible water quality. An average main break takes four hours to repair. You can find current water outages at www.dmww.com.
When the water comes back on, there will likely be air in your water service piping. It is a good idea to run the first water after an outage through a faucet that does not have an aerator screen, such as a bathtub. Open faucets slowly to allow the air to escape. Air will make a spurting or hissing sound as it escapes through the faucet. Once the water is flowing, allow the faucet to run for a minute or two. The first water may be cloudy due to air in the water or particles that dislodge as the pipes fill with water. This should clear fairly quickly. If water is cloudy throughout the house and it does not clear after allowing the water to run for several minutes, contact Des Moines Water Works.
If kitchen or bathroom faucets do not perform normally following a water outage, it may be necessary to remove the aerator screen. Typically, the aerator can simply be unscrewed from the faucet. Inspect the screen for small particles and rinse away any you find. Reinstall the aerator and test performance of the faucet again. If you experience difficulties such as low pressure throughout the house following a water outage, contact Des Moines Water Works at 283-8772 for assistance.
Did you know that Des Moines Water Works has owned about 100 acres of farm land at Maffitt Reservoir Park since 1942? In keeping with DMWW’s mission, and knowing that what we do on the land impacts the quality of our source water, we seek to adopt agricultural practices that provide protection to the water and soil resources under our ownership.
This fall, a cover crop was planted on DMWW’s Maffitt farm land. The cover crop was applied using a helicopter that planted seed in a standing soybean field. A mixture of rye (cool season grass/grain non-legumes) and hairy vetch (cool season annual legume) were planted.
Cover crops have been around for centuries, but are gaining in popularity because of their ability to control erosion, improve soil water moisture content, and the natural filtration of water through the soil profile. When the cover crop decays, it provides organic matter to produce beneficial soil organisms for soil fertility and soil health. Healthy soils improve the infiltration of water, leading to less flooding as well as reduced soil erosion and nutrient (nitrogen and phosphorus) leaching. According to an Ohio State University Extension report, Using Cover Crops to Improve Soil and Water Quality (2009), a pound of soil organic matter has the ability to absorb 18–20 pounds of water, reduces nutrient and pesticide runoff by 50% or more, decreases soil erosion by 90%, reduces sediment loading by 75%, and reduces pathogen loading by 60%.
By using cover crops and reducing reliance on agrichemicals for crop production, we help protect the health of family and friends and reduce water quality concerns arising from non-point pollution attributed to farming practices. At a time when the Raccoon and Des Moines River watersheds suffer from serious degradation due to nutrient contamination, this shift in agricultural systems can play a significant and positive role in revitalizing Iowa’s river systems. For more information about cover crops, visit Practical Farmers of Iowa at http://www.practicalfarmers.org/programs/Field-Crops_cover.php or Midwest Cover Crops Council at http://www.mccc.msu.edu/.