Sludge scum and grit take toll on Sitkas aging wastewater facility
Both the interior and exterior of Sitka’s wastewater treatment plant are in need of a revamp after environmental factors caused deterioration. (Photo by Katherine Rose/KCAW)In the Disney classic “Finding Nemo,” a clownfish escapes the clutches of a dangerous child by flinging itself into a sink. Washed down the drain, his aquarium buddies wave goodbye, but they’re not worried. All drains lead to the ocean, after all, right?Well, in Sitka that’s true. But first they lead to the wastewater treatment plant.“So that’s your raw wastewater. And this is what I would call a low-flow time of day,” said Shilo Williams, environmental superintendent for the City and Borough of Sitka, as she strolled through Sitka’s wastewater treatment plant.The plant is a huge building on Japonski Island, and it houses some of the biggest infrastructure in Sitka. Williams and her team deal with the three key stages of waste: sludge, scum and grit. Oh, and all of the detritus they capture that Sitkans shouldn’t flush.“This rack that you see right there?” Williams said, pointing to a grate that a small river of raw wastewater runs through as it enters the plant. “That’s a bar screen. What we’re collecting there are all of those things that people shouldn’t flush.”Williams said things like flushable wipes and feminine hygiene products are common catches.“We have to actually manually rake that every single day.”Raw wastewater enters the treatment facility. The water is strained through a rack first, to catch any “non-flushables.” (Photo by Katherine Rose/KCAW)After they strain all of the big junk out of the raw wastewater, they slow down the water, separating the heavy grit. Then the water is pumped to clarifiers — big pools where the “sludge” settles to the bottom and the “scum” is scraped off the top. The remaining water is pumped back into the ocean. Then the sludge goes to the “thickening” room.“This is one of the stinkier areas of the treatment plant,” Williams said as she walked over to a big circular tank where they remove more water from the sludge.After the thickening process is complete, they pump the dehydrated sludge to the “belt filter press.” Williams said they run the press once a week“What happens is literally squishing the sludge and getting all the water out,” Williams said. “One final squish right here and it’s going to fall into this hopper.”Then that dehydrated, flattened and rolled-up sludge is doused with lime and dropped 20 feet into a big box that they roll out to the landfill once a week.Each piece of equipment involved in the process is huge, expensive and aging. But it’s the more invisible parts of the wastewater treatment plant that Williams said are in desperate need of an upgrade: the ventilation system and key electrical wiring that powers all of the systems. Here’s why: Waste produces a gas called hydrogen sulfide, and hydrogen sulfide is highly corrosive.Back in her office, Williams keeps a science experiment on her desk to show just how corrosive the environment is.“This is the money that was in my desk drawer here,” Williams said as she held out a handful of blackened pennies and half dollars. “You can see a lot of it is unrecognizable, due to the corrosive environment.”She took out a piece of copper pipe that she pulled out of the ground in last September. She said it was shiny several months ago, but it’s unrecognizable as copper today.Williams said the ventilation system has been funneling some gases from the treatment plant back into their office space, making a lot of office equipment obsolete fast. Computers have to be encased in protective gear. Lab equipment has a shorter shelf life. And they have to use home printers instead of expensive, heavy-duty office printers, because they break so often.“Some of them will last a few months,” Williams said. “Mine I think I’ve had for about eight months. It doesn’t always function.”Williams said she and staff often blame the “wastewater gremlins” when a piece of office equipment suddenly stops working.It doesn’t just impact the hardware. Williams said it affects humans too. Worst case scenario, hydrogen sulfide exposure can be deadly. She said the levels aren’t that bad, but they’re noticeable, often causing nausea, along with burning of the throat and eyes.But the project to revamp the wastewater treatment plant is costly. When speaking to the Sitka Assembly last month, it was clear that in order to fund the $10 million dollar project, the Assembly would be required to move ahead with a plan to raise rates. But Assembly member Aaron Bean wondered if they couldn’t figure out a way to patch things up at the plant without spending so much money.“We need to do what we have to do to make what we have work. If we’re making the environment safe, that should be an alternative. It shouldn’t be, ‘Bulldoze it and replace it,’ is my point.”Sitka Public Works Director Michael Harmon said they’d already figured out how to make the project as cost-efficient as possible.“This is by no means bulldozing the project and starting over. You’d be looking at probably 60 million (dollars) to do that,” he said.Williams said it isn’t about making the plant glamorous — just safe.“The wastewater plant isn’t ever going to smell pretty, because it is a wastewater plant. But it will be much better. It won’t be as terrible as it is now.”Just like the filter in Nemo’s scuzzy aquarium, Williams hopes the renovations will help the wastewater team continue to keep Sitka’s scum and sludge and grit at bay.