One civil engineer says it would be less laborious and more cost-effective.
The current price on removing all lead service pipes in Flint, Michigan, is $55 million, as Mayor Karen Weaver announced at a press conference Tuesday.
In the wake of a drinking water crisis that’s risen to national attention, millions of dollars have poured into Flint from the state, the federal government, and private donors. It would be surprising if the city has trouble coming up with the money that Weaver is budgeting.
But what about for other towns around the U.S.? While the scope of the crisis and level of attention in Flint is unique, the infrastructure problem is not. All over the county, leaders are grappling with how to manage or replace aging, lead-addled water-distribution systems, with shrinking tax bases to boot. Does digging up all lead service lines to replace them make fiscal sense for cities deep in the red?
On his urban planning blog Strong Towns, the civil engineer Charles Marohn suggests that a more sound approach for cities in this situation may be to install an entirely new system that runs parallel to old lead pipes. The old system could stay in place and continue to serve the purpose it was really designed for: fighting fires.
Marohn explains why the super-high capacity of many municipal water systems doesn’t really serve the purpose of distributing drinking water:
Let’s say you live on a 50-foot lot and there is a small, eight-inch water pipe running in front of your house. There is 130 gallons sitting in that pipe right now. If the water was just for drinking, that’s enough for 260 people (half a gallon each). If we counted water for sanitation, it’s still enough for 26 people. And that’s just in the pipe. There are many multiples of that stored for you in other parts of the system. If the problem is getting people water for drinking and bathing, our current approach is overkill.
Replacing high-capacity systems with another high-capacity system—as Flint is gearing up to do—doesn’t make sense, Marohn believes. “We’d be putting back the same failed systems that are just a millstone around cities’ necks,” he tells CityLab. “They’re enormously expensive to maintain. We have to come up with some lighter touches.” Marohn suggests that the parallel drinking water system could be made of PVC and copper, and that most of these pipes could be simply plowed several feet into the ground—no expensive, laborioustrench-digging needed.
Is there wisdom in Marohn’s elegant-sounding proposal in the case of Flint? Marc Edwards, the Virginia Tech professor of civil engineering who has spearheaded lead testing in Flint, tells CityLab via email that it is “one viable approach for dealing with a distribution system that is over-sized for the current population.” He adds: “Someone will have to look at all the alternatives, and complete a cost-benefit analysis.”
What about for other cities drowning in infrastructure costs? Greg DiLoreto, the former president of the American Society of Civil Engineers, tells CityLab that Marohn’s two-pipe system approach could adequately provide lead-free drinking water, but that it would ignore the other big problem with the existing infrastructure: it’s old and failing.
“If you just put in drinking water pipes, then those lead pipes for fighting fires are still not reliable,” DiLoreto says. “Less expensive alternatives should be considered, but if the old system fails, then you haven’t got fire protection.”
That’s a big reason why most cities rely on high-capacity systems that essentially combine drinking water and firefighting water. But Marohn’s point is still valid. On top of dangerous lead levels in water systems well beyond Flint, the U.S. sees roughly 240,000 water main breaks per year, according to the American Society of Civil Engineers. It’s going to cost about $1 trillion to replace the pipes that need replacing.
Marohn’s proposal, while imperfect, is a reminder that cities scrambling to keep the most basic services running need lower-cost alternatives when it comes to providing safe, reliable infrastructure—without cutting corners. As Flint knows all too well, that can lead to tragedy.