Some neighborhoods in the parish that have experienced flooding seem to believe that the installation of subsurface drainage would solve the problem.
But St. Charles Parish Public Works Director Sam Scholle said that’s not the case.
In fact, Scholle said subsurface drainage, which is a perforated conduit installed below the ground to intercept, collect and convey drainage water, would make things worse.
“The subsurface will actually make it worse because it has less ponding and less retention,” he said. “If you get a significant rain, you flood immediately.”
Most of the neighborhoods that want subsurface drainage currently have open swail ditches. If the parish were to come in and switch those neighborhoods to an underground system, all the culverts would have to be replaced as well. This would ensure rainwater could get to the pumps to drain neighborhoods effectively.
“The issues we’ve had in the past while spot changing culverts is that you don’t have a plan and you don’t have the outflow to match it,” Scholle said. “You have to match the whole system. Even if you build a new subdivision and you do everything according to what our current ordinance is, once that drainage leaves that particular subdivision its got to flow somewhere.”
On the East Bank, virtually everything has to line up with Lake Pontchartrain. The numerous railroad tracks that stand between the lake and the neighborhood present a problem.
“What happens with all these subdivisions on the East Bank is that the challenge is to get it through the railroad tracks, through all of those subdivisions, all the way to the lake,” Scholle said. “There are numerous obstacles to getting it there.”
Scholle said instead of changing drainage systems for each neighborhood, the parish is trying to improve existing infrastructure.
“What we’re concentrating on is getting the water out of the areas and concentrating on how to fix that,” he said. “We saw in Des Allemands that we could not get the water out because we didn’t have the outflow to get it out. Whether it be culverts, whether you could get it under Highway 90, you couldn’t get it all the way to the pumping station.”
Subsurface drainage would just compound the problem, he said.
“I know that’s not pleasant for the people to hear, but that’s the facts of it,” Scholle said.
The parish is currently putting together a systematic plan to get the water out of neighborhoods. If cleaning the ditches doesn’t work, the parish may have to pump it out.
“We have 46 pumps already, and when it’s over with, we may have many more than that,” Scholle said. “Because another issue is that every place you have a railroad, if the jack and bore is too high, you have to either go to the railroad and get permits to put new jack and bores in, which takes years to get, or you have to try and pump it through or pump it under.”
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