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Fat, oil, grease bad for health of sewer system

Chris King, operator at the Willmar Wastewater Treatment Plant, holds a chunk of fats, oil and grease taken from the underground sanitary sewer system. The substances congeal and form huge clogs that back up sewers and cause other problems. Treatment plant employees ask residential and business customers to help keep fats, oil and grease out of the sewer system. (Tribune photo by David Little)

WILLMAR -- Just as plaque buildup in arteries restricts blood supply and can cause a heart attack, accumulation of fats, oils and grease in sewer lines can cause health hazards, damage home interiors and threaten the environment.

"Think about it like heart disease,'' says Chris King, an operator at Willmar's Wastewater Treatment Plant. "If you put a lot of fats, oils and grease in your body, it's going to clog your arteries. The same thing with sewer lines.''

Colleen Thompson, wastewater plant superintendent, agrees with the analogy.

"We've got pumps out in our collection system and we want to maintain a healthy collection system so that we're not clogging up the pipes,'' says Thompson.

The wastewater plant serves 8,300 residential customers and 825 non-residential customers. Fats, oils and grease -- known as FOG in the wastewater treatment business -- enter the sewer system from household drains and from poorly maintained restaurant and business grease traps. Such traps are designed to keep grease out of the system.

An increasingly common cause of sewer line overflows is blockage by thick, unsightly and smelly accumulations of the so-called FOG in the bottom of wet wells. A wet well is a compartment or tank in which wastewater is collected. Workers must use shovels to break up the foul stuff so that it can be sucked out with a high-pressure vacuum.

King displayed a chunk for the Tribune. It resembled a big rock. The white stuff surrounding the chunk was foam from foam cups.

"It can be a big problem,'' says King. "The stuff hardens to the point where it's like rock. You have to go down into the sewer. I can kick it with my foot as hard as I can and I won't even dent it. It tends to accumulate and keeps building up in there until it's just a huge grease mat.''

Thompson says FOG has always been an issue with the treatment plant. But with the new treatment plant set to open in a few months, Thompson says now is a good time to remind homeowners and businesses they need to do their part to better maintain the system.

Fats, oils and grease are probably a good food source for the bacteria that will be eating the waste at the new treatment plant, says Thompson.

"The problem is it just becomes a maintenance issue in the collection system,'' she says. "It narrows the pipes, which then could mean you're not delivering as much wastewater out to the facility and then it could back up into people's homes.''

City ordinance prohibits certain discharges into the sewer system. The best way to keep the sewer system flowing properly is to use the sewer for what is was intended -- to carry wastewater.

Items commonly found in blocked sewers include:

- Grease and oils: (bacon grease, peanut butter, frying oils). These will harden in the drain, stick to the sides and trap other items filling the drain. Kandiyohi County residents can dispose of cooking oil free at the city treatment plant.

- Paper products: (baby wipes, diapers, feminine napkins, cigarettes, cotton balls, cotton swabs, paper towels and tissues). These do not dissolve in the line, but build up and result in clogs.

- Lint and hair: These fine materials mat in the line and are common sink clog problems.

- Roots: Roots from vegetation, such as lilacs, elm trees, maples and willows planted over sewer lines can break into clay tile pipes, resulting in blockage.

- Other items found in sewers include condoms, underwear, needles, toys, stir sticks, plastic tableware, steel shards and paint.

City employees are responsible for maintaining the 93.5 miles of sanitary sewer lines, 1,709 manholes and 25 lift stations.

But residential and non-residential customers are responsible for maintaining the lateral (sewer line) from their home or business to the sewer line in the street. Following these simple rules will help keep things flowing properly:

- Use the garbage disposal sparingly and flush with plenty of water. When possible, put food scraps in the garbage or compost.

- Store grease in a container and dispose of hardened grease in the trash.

- Put cat litter, diapers, baby wipes, feminine napkins, cigarettes, cotton balls, cotton swabs, paper towels and tissues in the trash, not the toilet.

- Start a compost pile for coffee grounds, egg shells and food waste, except meat, dairy products and bones (put these in the trash).

- Screen all drains. Use a lint trap on your laundry hose.

- Avoid planting trees or bushes over your sewer line.

- Periodically have your sewer line cleaned.

- Never put medicines or hazardous materials down the drain. Dispose of them at a household hazardous waste site.

David Little
David Little covers the Willmar City Council, Willmar Municipal Utilities and other city news.
(320) 235-1150