Where does your poop go? From flush to renewed water
A Boise neighborhood association’s concerns about the possible diversion of treated wastewater into a canal used by residents has put a spotlight on the city plants that treat the wastewater.
“Right now there isn’t wastewater in the canal,” said Richard Llewellyn, president of the North West Neighborhood Association, in an interview. “But the city wants to run wastewater down our canal.”
The treated effluent comes from the city-run Lander Street Water Renewal Facility at 790 Lander St., west of State Street and north of Veteran’s Memorial Parkway near the Greenbelt. It’s one of two such plants; the other, the West Boise plant, is below the edge of the Bench off Chinden Boulevard, across from the former Hewlett Packard campus.
Their treated water now flows directly into the Boise River. To conserve water, city officials are considering diverting the water leaving the Lander Street plant into the Farmers Union Canal, which runs through the North West neighborhood.
“People use the canal water for sprinklers, their vegetable garden, and children and pets play in it,” Llewellyn said. “People see it as a stream, and interact with it more than a pipe of water.”
Playing in the canal is not an official use of the canal, and according to the city can pose a public safety concern. City officials say discharged water meets federal standards and is clean enough to swim and fish in, though not to drink.
But Llewellyn and other stakeholders worry that the treated wastewater contains what are called contaminants of emerging concern, or new chemicals for which the Environmental Protection Agency does not yet have standards.
Contaminants of emerging concern are compounds from manmade processes that can be biologically active at low levels, Llewellyn said. Examples include pharmaceuticals that are poured down the toilet and birth-control pills.
“The regulations have not caught up with technology and science,” he said.
City officials acknowledge that emerging-concern contaminants are present in the effluent. “Medicines and microplastics could be in this water,” said Augie Gabreilli, water education coordinator at the plant. “We do not treat for that.”
They also acknowledge that regulations have not caught up. The city tests the wastewater to make sure it complies with EPA and Idaho Department of Environmental Quality requirements, but there are no standards set yet for emerging contaminants.
“This water is safe and up to standard,” Gabrielli said in an interview. “We can touch it, we can fish in it, we can swim in it, we can use it for agriculture. The only thing it is not good for is drinking.”
Three employees of the city Public Works Department took an Idaho Statesman reporter and photographer on a tour of the West Boise plant to demonstrate what it does. (The Lander Street plant is undergoing construction to expand its capacity.)
The used water cycle
The West Boise plant was built in 1976 in response to the Clean Water Act, which regulates pollutants and water quality. The plant screens, treats and cleans 15 million to 17 million gallons per day. (According to Gabrielli, the highest flow day each year is Super Bowl Sunday.)
They call untreated wastewater “used water.” It is any water that has been affected by human use, such as domestic or industrial usage and sewer inflow. They call treated wastewater “renewed water,” since it is usable for most purposes.
More than 900 miles of pipes move water from Boise homes and workplaces to the West Boise renewal plant and its sibling, the Lander Street Water Renewal Facility west of State Street and north of Veteran’s Memorial Parkway.
The first step is physical trash removal. Used water arrives at the West Boise plant and is pumped up 30 feet to the second floor to screens that remove the trash.
Over 8,000 pounds of trash is removed daily from Boise’s used water. One of the most common pieces of trash is flushable wipes, which despite the name usually do not degrade from toilet to treatment plant.
Next, the water is clarified using gravity. This step removes about 30% of the pollutants.
“Like a cup of hot chocolate that sits around, sludge forms on the bottom of the clarification tank,” Gabrielli said. “But this is not hot chocolate, this is poop.”
In the next step, microorganisms remove more pollutants like ammonia and phosphorus.
“Micro-organisms from our gut also go down the drain when we use the bathroom,” Gabrielli said. “We use those naturally occurring micro-organisms in your gut. We celebrate your micro-organisms here.”
A grid of aerators adds oxygen to the river of brown, bubbling water to keep the microbes alive.
In a secondary clarifier, the microorganisms settle out of the water, collect together, then are recycled back into the aeration basin.
The water then moves to a post-treatment aeration basin to add oxygen back into the water. A grid of aeration panels at the bottom of the pit circulates oxygen into the water.
“Many microorganisms need oxygen to remove pollutants, so after they have done their work we have to put oxygen back into the water for fish and invertebrates,” Gabrielli said.
The last step is ultraviolet light that disinfects the water and kills the microorganisms so the reused water leaving the plant is safe to enter the river.
Canal concerns remain
City’s permits are updated once every five years to ensure compliance with state and federal wastewater regulations.
“Twenty years ago we were not regulating for phosphorus, or temperature, or mercury,” said Stephan Burgos, director of the Boise public works department, “but we are now, because we recognize they have an impact on the fish. We are still at the point of research with contaminants of emerging concern, and we are staying compliant with the EPA standard of clean water.”
The Farmers Union Canal plan is one of several the city is considering as options for water renewal to conserve water in the future. According to Burgos, 86% to 96% of residents in three focus groups supported using water renewal for non-potable uses like irrigation. The city is drafting a water renewal program to bring before the City Council and mayor in the coming months.
Llewellyn discovered the plan in the city “Playbook,” a 20-page document with the city’s priority projects for 2019 through 2023. It says the city is planning to develop infrastructure and acquire permits to run treated water down Farmers Union Canal for agriculture beginning in 2024.
Earlier this year, a group of residents in the North West neighborhood including Llewellyn brought their concerns to the city. The group met after-hours for several hours with Burgos and other public works officials.
“To me the process is all wrong, but it is not intentional by the city,” Llewellyn said. “In my mind we need to hit the pause button to consider the consequences.”
The city is working to increase residents’ input to the proposed canal changes and will include a representative from the North West Neighborhood Association in future work.
Haley Falconer, senior manager for Boise’s environmental division, thinks the water is safe.
At the end of the tour, as she looked out at the renewed water pouring out of the pipe entering the south canal of the Boise River, she said: “If I did not have a meeting at 11, I would totally jump in that.”
This story has been revised. An earlier version incorrectly summarized participation by Richard Llewellyn, president of the North West Neighborhood Association, and other neighborhood stakeholders in planning for these proposed Farmers Union Canal changes.
Rachel Hager is writing for the Idaho Statesman this summer on a fellowship through the American Association for the Advancement of Science. She is a master’s student in ecology at Utah State University and earned a bachelor’s degree in biology at Bryn Mawr College.