by Jeff Weise
6/20/2010

By RUDOLPH BUSH / The Dallas Morning News
rbush@dallasnews.com

At Dallas Water Utilities, they still don't know exactly why, after all those years, the old cast-iron pipe gave way last month and sent a flood of water into the basement of the Dallas County Records Building.
For more than 90 years, the stretch of 8-inch line did its job just fine - better than fine in fact, since it lasted nearly twice as long as it was supposed to. While some people were surprised to learn that such an old conveyance was still being put to use under downtown, they shouldn't have been.

Dallas - like any big city of a certain age - supports thousands of miles of buried pipeline infrastructure that is all but forgotten until the day it can't be ignored.

Cesar Baptista, an assistant director at Dallas Water Utilities, said that about half of Dallas' 4,900 miles of water and wastewater lines is more than 50 years old - the expected life span of the typical line.
"We've got some that are close to 100 years old. They are still performing," he said.

So why not just replace them with new pipes to avoid another near-catastrophe like the records building flood?

The short answer is that it's not as simple as that.

"The system did not just materialize overnight. It got built over a number of decades. Even if you were able to financially, you can't replace everything at once. The city would be in chaos," Baptista said.
Next year, the utility plans to replace about 120 miles of pipeline - and is asking to raise the retail water rate 4.2 percent so it can address a 500-mile repair backlog in coming years.

Even when that backlog is addressed, there will still be hundreds of miles of pipes past their prime.  And old pipes won't necessarily be the first ones on the list to be replaced.
Age is just one factor the utility considers when it looks to replace water lines, Baptista said.

Pipes that break frequently will be the first to be dealt with, obviously.

Other factors, like how critical a pipe is to the system, how much water it carries and what type of soil it is in will be factored in as well.  It's also important to replace pipes in areas where other infrastructure projects are under way. If the gas company or DART is tearing up a street to do work, the water department will examine whether its lines need to be replaced at the same time.

Piggybacking on the other work saves money and makes the job much simpler, Baptista said. That's a big part of the reason downtown - which has plenty of very old water lines - also has a large share of newer lines.
When DART built its tracks along Pacific Avenue, new water lines went in along with them. And when streets are pulled up for telecommunications or electrical lines that are buried downtown, water department crews are there too, Baptista said.

He estimates that 60 percent of downtown's lines are at least 50 years old. In some neighborhoods, particularly in North Dallas, almost all of the lines are older than 50.
Dallas is far from alone in that regard. Indeed, most major cities in the country are in a similar state.  "If you are talking about a city like Dallas, especially in the downtown area where things have been there awhile, you're going to see these sorts of main breaks. We're seeing these sorts of main breaks all over," said Kelly Brumbelow, associate professor of civil engineering at Texas A&M University.

Often, it's hard to generate much interest in replacing those lines because it's very expensive and, when repairs are made, people can't see where their money went, he said.
"A road gets worn out ... people feel that as they drive over it. Nobody really thinks about a water line until there is a problem," Brumbelow said.
Even when a water line breaks, it doesn't necessarily draw attention, unless it happens to, say, flood a critical government building and shut down a countywide computer system for three days.

In a typical year, Dallas Water Utilities will respond to 2,000 to 2,500 water line breaks, Baptista said. Only a tiny fraction of those will make the news.
It would be nice, he said, if the water department could eliminate every line that has passed its prime and never have another one break because of age.
But don't hold your breath.

"For every utility, that would be the most idealistic goal, but financially and practically, it's virtually impossible," he said.