Archive for February, 2014

February 20, 2014

Taste and Odor Episode Due to Runoff from Recent Snowmelt

Des Moines Water Works uses both the Raccoon and Des Moines Rivers as water sources. By using surface water, seasonal variations can occur. The recent warm-up in temperatures has caused increased runoff into our water supply, requiring Des Moines Water Works to use more chlorine to achieve the desired chlorine levels in the finished product.

Both rivers are currently experiencing elevated levels of ammonia. Disinfection with chlorine is more difficult when ammonia is present in source waters. Ammonia consumes chlorine, leaving it unavailable for disinfection. This requires addition of extra chlorine to eliminate the ammonia and maintain adequate disinfection. For these reasons, chlorine levels have been purposefully higher for the past three weeks. Chlorine levels in the water leaving Des Moines Water Works’ treatment plants are monitored continuously to ensure they do not exceed the maximum allowable limit set by Environmental Protection Agency (EPA).

Finished drinking water from Des Moines Water Works is safe to consume. Some people are more sensitive to these subtle changes in taste or odors. These conditions will improve as the weather stabilizes and levels of runoff decrease.

Posted by: Laura Sarcone 4 Comments
Labels: , , , Posted in Customer Service, Source Water, Water Quality, Water Treatment February 14, 2014

Main Breaks by the Numbers: 200 Main Breaks in First Six Weeks of 2014

DSC_2681Despite an aggressive preventative maintenance program in Central Iowa, water mains around Des Moines are breaking at a record number, Cold weather and corrosion of pipes have teamed up to cause pipe failures. The extreme drop in mercury drives frost penetration to a greater depth.  Deeper frost penetration causes the corroded water mains to break. With expected warmer temperatures in the coming days, it can cause the frost line to move quickly and cause breaks as well.

The American Society of Civil Engineers’ 2013 grade for America’s drinking water infrastructure was a D, which is no surprise considering Des Moines Water Works has repaired a record number of main breaks in one month: 122 breaks in January. To date, Des Moines Water Works crews have repaired 200 main breaks, with as many as 12 in a single day.

The 10 year average for total main breaks in a year is 290. On average, half of the main breaks occur in the three winter months of December, January and February.  The total number of main breaks in 2013 was 342. The highest number of breaks in one year was 365, set in 1988.

The average cost of a main break is around $5,000-7,000 for labor, materials and equipment. This does not account for the loss of water at a main break. The 2014 budget for emergency repairs is approximately $1.5 million. So far in 2014, Des Moines Water Works has spent approximately $1 million in repairing water mains.  Any impact of this year’s main break experience will be analyzed when determining the 2015 water rates.

Though largely out of sight and out of mind, Des Moines Water Works operates and maintains more than 1,300 miles of underground water mains distributing finished drinking water to homes and business in Des Moines and surrounding communities. The pipes in the distribution system are made from cast iron, concrete and plastic and also vary in size, from half-inch diameter service lines to 48-inch diameter transmission mains. Pipes installed between 1940 and 1960 are leading to most of the main breaks in Des Moines. The oldest pipe (circa 1900), which can be found in Downtown Des Moines, is some of the best in the distribution system.

“While every main break is different, fixing it quickly and safely are top priorities,” said Bill Stowe, CEO and General Manager, Des Moines Water Works. “Our goal is to minimize disruption to our customers who live, work and commute in the area.”

Des Moines Water Works invests millions of dollars each year in infrastructure improvements. The 2014 capital improvements budget includes $2.2 million for water main replacement within the Des Moines water distribution system. These funds will be used to replace water mains that have reached their useful life expectancy – water mains with a high occurrence of breaks.

Posted by: Laura Sarcone No Comments
Labels: , , , , Posted in About Us, Customers, Infrastructure