Not since 2010 has Central Arkansas Water experienced as many water-main breaks during winter months as the number that occurred during this past winter, records show.
From December through February, 203 water pipes broke across the utility’s coverage area, which totals about 2,300 miles of pipe throughout Pulaski County. That’s up 64 percent from the 124 main breaks during that same span in the previous winter.
Officials are naming a variety of factors as the cause of the uptick, including lower-than-normal temperatures, a velocity increase that resulted from higher water demand, and the age and make of the pipes.
The agency spent $102,000 more than the $1,035,000 budgeted for main repairs and maintenance in January and February. But because customers used more water by letting their faucets drip to prevent freezing, the utility’s revenue during those months set a record compared with the same months in previous years.
Revenue for January and February was $424,000 over the expected $6,998,000.
“When you have extreme weather, whether it’s cold winters or hot summers, you may have a higher amount of breaks, but you’ll always have higher revenue as well,” said John Tynan, the agency’s director of public affairs.
In hot summers customers use more water for swimming pools and lawn care, and in cold winters customers increase water usage by letting their faucets drip, Tynan said. When demand is high the velocity that water travels through the pipes increases and sometimes causes pipes to leak or break.
This past winter, temperatures in central Arkansas dropped as low as 9 degrees, and a total of 4 inches of snow and ice fell from December through February. And back-to-back storms allowed for little relief.
In the 2009-10 winter, temperatures dropped to 12 degrees and 8.7 inches of snow fell in the region. The number of pipe breaks rose to 208 that winter, a 78 percent increase from the winter before.
“It’s not always just how cold it is, but also a matter of do we have a spell where it stays cold for a long period of time,” said John Robinson, a meteorologist at the National Weather Service in North Little Rock.
According to Robinson, central Arkansas has seen five winters with below-average temperatures over the past 27 years. They were the most recent winter, the 2010-11 winter, 2009-10, 2002-03 and 2000-01.
When falling temperatures begin to freeze water, the liquid expands and puts pressure on whatever is containing it. Central Arkansas Water’s Chief Executive Officer Graham Rich said the average water temperature carried by the agency’s pipes this past winter was only a few degrees lower than the previous winter, but the change still might account for some of the increase in pipe breaks.
From December through February, the water temperature averaged about 52 degrees. Over the same months the winter before, the temperature averaged about 57 degrees.
“When you get that first really big change in water temperature, what we see is that it causes the pipes to either expand or contract, and on older cast iron and galvanized piping, that has the tendency to cause it to break. It’s more brittle than PVC or ductile iron pipe,” Rich said.
PVC stands for polyvinyl chloride - the type of plastic used to make the pipe.
An analysis of pipe material in main breaks in 2013 shows that though galvanized pipe accounts for only 6 percent of the agency’s total, 38 percent - or 251 of 664 - of the main breaks last year were in galvanized pipe.
The agency’s galvanized pipes are typically 2 to 3 inches in diameter, so they don’t cause as big of a problem asa larger pipe if they do leak, and they are easier to repair, Chief Operations Officer Thad Luther said. Still, the pipe is dated.
“A large percentage of our galvanized pipe is past its life expectancy. We use 50 years on that. The weighted age of ours is 56 years,” Luther said.
As the agency replaces pipe, it has turned to PVC. Right now, 19 percent of the agency’s pipes are PVC. The majority is cast iron or ductile iron, and a small percentage is asbestos cement.
Since 2001, the agency has spent an average of $1.7 million each year on proactive replacement of pipe, with an average of 4.1 miles being replaced yearly, Rich said.
“We should be replacing a whole lot more than that,” he added. “It needs to be significantly increased, but to get to that point it’s going to take a number of years. We need to put the process in place to start increasing the amount and have a dedicated commitment to replace a certain amount of pipe every year.”
The issue will be a topic of discussion at a May 28 Central Arkansas Water Board of Commissioners retreat. Agency staff members also plan to give a presentation about the winter weather’s effect on pipe breakage at a regular commission meeting April 10.
Repair cost will continue to increase if the agency doesn’t start replacing more pipe, Rich said. Factoring in preventive maintenance, new construction and repairs, the agency installed more pipe in the 1970s than any other decade, at 487 miles. Since 2010, pipe installation hit a low not seen since the 1930s, with just 63 miles installed.
About 35 percent - or 800 miles - of the agency’s pipe is older than 45 years. The oldest is 114 years. Age plays a role in how worn out a pipe is, but Tynan noted that a pipe’s material is still more indicative of how prone it is to break. Some of the 100-year-old cast iron pipes in the heart of Little Rock, for example, are operating without any issues, he said.
Tynan also warned that there is a balance that needs to be accomplished in how often pipe is replaced.
“You could replace every stick every 25 to 50 years, but customer rates and the construction associated with doing that would be substantial,” Tynan said. “How you strike the appropriate balance for asset replacement and charging customers for that asset replacement is kind of the heart of the matter for asset management.”
Front Section, Pages 1 on 03/31/2014