Public Works officials: Sewage plant needs upgrades to handle fats, oils, grease
Rochester's Water Reclamation Plant must be retrofitted to accept an increasing load of fats, oils and grease flowing primarily from restaurants into the system, plant officials say.
The city included $16 million in its 2014-18 capital improvements program budget for building a receiving station and equipment to handle FOG, as the industry calls the waste of fats, oils and grease. However, Water Reclamation Plant Manager Chet Welle said he and his staff are exploring cheaper alternatives.
FOG comes to the plant mainly through the sewer lines, although it is not supposed to, according to city ordinance. Restaurants are required to use grease traps, clean them out regularly and have the waste transported to a sewage treatment plant equipped to handle it.
Many Rochester restaurants do not because there is no convenient, cost-effective place to take the waste, Welle said. Not wanting to deal with the cost and hassle of trucking FOG out of the city, most restaurants just dump the grease down the drain, and that causes problems for the sewer lines. When the grease goes down the drain it's hot liquid. But as it moves into the sewer lines, it cools and clumps up.
"So, if you have a 12-inch diameter sewer pipe, you'll get a 10-inch diameter plug of grease. And then we have to go in there and rod it out and jet it out to get it moving. And it's really hard to work with in the plant," Welle said, adding that the city has dealt with several plugged-up sewer pipes during the last couple of months.
"It's a cost to our sewer collection system to clean out the sewer lines and there's not a good remedy for it right now, except for some regional plants that have started to accept FOG. We're not one of them at this point. So, we need to do it sometime in the future," he said.
Enforcing the city ordinance requiring restaurants to dispose of FOG rather than pour it down the drain is problematic.
"We don't have personnel to inspect that, necessarily. And even if we enforced it, then we're forcing them to do something ... when there's not good alternatives," he said.
FOG is a problem in the sewer lines, but once it gets into the plant's biological waste digestor tanks, it actually becomes an asset. The material is rich in its ability to produce methane gas, which the plant uses as an energy source to offset utility costs.
"So, once we get it here, we love it," Welle said.
Initial research into the best way to receive and process FOG at the Rochester Water Reclamation Plant resulted in a $16.3 million cost estimate. But Welle said that would be for a comprehensive build-out, and there are less expensive ways to get by for a while.
"We envision finding a way to do something in the interim, just so we can receive it, and then as we go forward, start to work toward a better program," he said.
Public Works and plant staff are working on a plan to bring to the Rochester City Council, probably in June or July, he said.
Given that Rochester is expected to go through another growth spurt during the next 20 years because of the Destination Medical Center initiative, Welle said it makes sense now to retrofit the treatment plant so it can begin accepting FOG, and "high-strength" wastes from food processing businesses.
As for the plant's overall capacity, it will need to expand when Rochester's population is poised to reach about 126,000. It is approaching 109,000 today. The plant has plenty of land on which to expand — enough to handle a population of 300,000, Welle said.