Sewers Are Getting Clogged with Grease From Commercial Disposals

It’s estimated that 544,000 gallons of grease slip down Seattle’s drains each month, enough to fill seven large swimming pools. Most of it comes from dirty dishes and food waste, and it’s a problem.

In the last five years, grease-clogged pipes caused about one-third of Seattle’s sewer backups, according to Seattle Public Utilities. There were 147 such incidents between 2003 and 2009, but that doesn’t count the times when residents called SPU only to discover that the blockage was in the side sewer on their property.

Doctors warn how too much cholesterol in your diet can plug your arteries. That same phenomenon is wreaking havoc on Seattle’s underground sewer pipes. If some of those pipes were your arteries, you’d be having chest pains.

In this case, it just means stinky water is bubbling up somewhere you’d rather not have it.

“The City of Seattle is really working on getting the word out that it is a problem,” said Ryean-Marie Tuomisto, coordinator of the city’s fats, oils and grease program, or what utility workers call “FOG.”

It’s an issue for any city or county with older sewer pipes and residents who consume animal products. Cities have taken various approaches to reducing the amount of grease discharge, either through stepped-up recycling programs or stronger regulations. Last year in Fairfax County, Va., officials sued donut giant Krispy Kreme for $20 million, alleging that years of greasy waste from a donut plant had fouled up the sewer system.

The City of Seattle prohibits directly dumping grease down the drain and restricts how much grease can be in your wastewater. Leftover grease should be thrown out with solid wastes. Most restaurants use commercial garbage disposals to grind up their food waste which flushes it directly into the sewer system.

But there is another culprit that people often miss — the scraps on their dishes, Tuomisto said. If you don’t thoroughly scrape the grease and muck into the trash, it rinses off in a scalding dishwash and accumulates in the city’s pipes.

That grease after your steak? Trouble. Sour cream from your nachos? Trouble. The butter and gravy left from your potatoes? More trouble.

“Most of the grease build-up that comes into our system is from your basic dishwashing in a 3-compartment sink,” Tuomisto said. “The slow discharge into the system accumulates and causes problems.”

There, it cools down and solidifies, glomming around tree roots or other debris floating in wastewater. Goop sticks to the pipes; forming a rock-hard substance and making sewer lines look like tunnels of bacon fat.

Restaurants, which wash dishes in bulk, can be required to install grease traps or interceptors to catch grease before it washes down the pipes with dishwater. But not every Seattle restaurant has one because many businesses opened before changes in the plumbing code related to pre-treatment devices. Of 2,600 “food service establishments,” which include bakeries, groceries and restaurants that seat more than 12 people, only 1,000 have pre-treatment devices, according to SPU estimates.

Within the past few years, SPU has begun tracking “grease hotspots” — or places where crews are called to clean FOG from pipes every six months or more. The goal is to work with restaurants or residential areas where grease is a problem and reduce their discharge, and gather better data on pipes. SPU officials say they’re considering stronger regulations on grease-traps and how much FOG can be in wastewater coming from an establishment with commercial garbage disposers.

Generally, there are hotspots around concentrations of restaurants downtown, on Capitol Hill and in West Seattle.

“There are back-up problems, really everywhere,” said Julie Howell, Pollution Prevention Program Coordinator with SPU.

Slightly more than half of the city’s grease clogs are in residential neighborhoods, Howell said. About 70 percent of residential sewer lines that require excessive cleaning for grease trace back to single-family residences, she said.

The biggest culprit in commercial kitchens is often is commercial garbage disposals. Employees toss food scraps into the disposal, thinking the ground-up mess will safely drain down through the pipes. But that’s not what happens.

“One thing that has been a real surprise in this industry — one thing people have learned over time is that there is much bigger commercial garbage disposer component than people might think,” she said.

SPU is trying to get the message out to residents and restaurateurs: Avoid using commercial garbage disposals and do a better job of scraping your plates into the trash or food recycling bin. Some cities, such as New York and Raleigh, N.C., have tried banning disposals outright, although public outcry led to the restrictions being lifted.

Each time a city crew has to clean out the pipes, it costs about $1,500, according to SPU. Doing the math, that’s about $220,000 for the 147 back-ups. That doesn’t include claims filed by utility customers who experience sewer back-ups, or lost revenue when the Health Department shuts down restaurants due to sewer backs-up.

“If 30 percent of our back-ups are preventable, that is a big deal,” Howell said.

Jack Miller, owner of the Husky Deli on California Avenue Southwest at The Junction in West Seattle, said he was surprised a year ago when the city suggested he install a grease trap.

The sewer line beneath California Avenue was gunked with too much grease — an accumulation from establishments in the area, according to SPU. So, Tuomisto began visiting them and trying to figure out the problem.

Miller didn’t think he was a contributor, since he makes sandwiches and pasta salads, and doesn’t deep-fry any food. But the third-generation family-owned deli also makes delicious homemade ice cream. When employees washed out empty tubs from the 40 flavors, dairy fat sloshed down the drain.

Miller’s now more careful about washing dishes, he said. He followed SPU’s instructions and installed a steel grease trap under his sink in October, which is inspected regularly. The “brown grease” that collects is taken to a plant on West Marginal Way.

“I really felt like we didn’t put out much grease and that it would be waste of time. But I was shocked to see how much grease we put out. It was kind of embarrassing,” he said. “I never looked at ice cream as grease. We were just rinsing the pans, and dumping ice cream rinse water in there.”

He paid about $3,000 for the grease trap, he said, but didn’t mind spending the money, since it also helps keep his side sewer clear.

A clogged side sewer, which connects your property to the main line, is the property owner’s responsibility and can cost more than $1,000 to fix.

SPU is spreading the word about grease to residences through posters, door hangers, signs on utility trucks and information on the agency’s Web site. Here are some quick tips on how to prevent grease from clogging your sewer:

Never pour oil of grease down the drain. Allow cooked fats, oil or grease to cool and pour them into a disposal container than can be tossed out with solid wastes.

Thoroughly scrape plates to remove leftover fat, oil, grease and food waste from pots, pans and cooking equipment prior to rinsing. Use paper towels, if needed, to wipe greasy dishes before dishwashing.

Use sink strainers to catch food waste during dishwashing. Avoid using garbage disposals.

For more information on disposing and recycling grease, visit www.resourceventure.org. SPU also keeps this list of local companies that handle grease recycling and maintenance of pre-treatment devices.