What lurks beneath the streets | PostIndependent.com

What lurks beneath the streets

Glenwood Springs wastewater plant worker Trent Mahaffey stands on a catwalk above the oxidation ditch at the city's wastewater plant. Mahaffey points out that certain things, like grease and cleaning wipes, should never go down the drain.
Christopher Mullen / Post Independent |

Do not flush

• Grease, fat, oils

• Prescription drugs

• Trash

• Cleaning wipes

• Feminine hygiene products

• Medical supplies

• Condoms

• Hair and beauty supplies

• Disposable diapers, nursing pads, baby wipes

Source: City of Glenwood Springs Wastewater Treatment Plant

A recent story in the Denver Post calling attention to the fact that most body and household cleaning wipes should never be flushed down the toilet prompted city of Glenwood Springs wastewater officials to do a little research.

And while the various types of pre-moistened, non-biodegradable wipes are definitely a no-no down the drain, you wouldn’t believe what all wastewater workers have found clogging up the city’s sewer system over the years.

Like the time about 15 years ago when workers discovered an unopened 12-pack of beer beneath the streets.

“The theory was that a contractor was laying pipe and set it down, then left and forgot about it,” said city wastewater worker Trent Mahaffey, who wasn’t around at the time but has heard that and other stories from longtime sewer workers.

Other items that have been found in the sewer were likely placed there or flushed more deliberately, he said.

For about six months last year, for instance, workers kept finding empty large, contractor-size plastic trash bags in the wet well in one particular neighborhood, Mahaffey said.

“We never could trace it,” he said. “But that’s something that can definitely cause a classic backup in the system, and whoever sends something like that down the line is probably going to see that backup in their house.”

Smaller, plastic shopping bags are also common, Mahaffey said, because they can actually be flushed down the toilet. But that, too, is more likely to cause a backup in someone’s house before it even makes it into the city sewer system, he said.

Other items found in the wet wells and elsewhere in the wastewater collection system have included clothing, towels, live pet fish, a pump hose from a recreational vehicle, various pieces of jewelry and even a rusty handgun.

In recent years, the growing popularity of pre-moistened wipes, from baby wipes to household cleaning wipes, has presented a new problem for municipal wastewater system operators.

The Denver Post reported earlier this month that sewer problems in an Aurora neighborhood were traced to body wipes that were clogging the sewer main, causing toilets to back up into people’s houses.

Unlike toilet paper, most of those types of wipes are not biodegradable and are not meant to be flushed.

“Wipes are not like your normal, everyday tissue paper,” Mahaffey said. “They’re more fibrous, and they don’t pump easily so they can get caught up in the collection system before they ever enter the plant. It’s an expensive operation to remove them, and that costs everyone in the end.”

Many troubles are lower tech, though.

The biggest single problem, Mahaffey said, is when people dump cooking grease down the drain.

“That’s usually the most problematic for us, actually, because it accumulates on the sides of the pipes and in the tanks,” he said.

The remedy is to either push it through the system with special equipment or to pour chemicals into the sewer lines to dissolve it, he said.

“We’re constantly educating the public to keep grease out of there in the first place,” Mahaffey said. “Put it in a can and dispose of it in the trash.”

Another common problem is when tree roots grow and found their way into private service lines and sometimes the city’s sewer main, he said.

“You don’t want to plant trees directly above a service line,” Mahaffey said, adding a plumber should be able to locate a line for a homeowner who is wanting to plant new trees.

It’s better than dealing with a damaged service line, which can cost upwards of $5,000 to $10,000 to replace, he said.


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