Part II: what happens to waste water in Williams
WILLIAMS, Ariz. — Water management in Williams doesn’t just end when it streams through the tap in a house or business. A parallel management process begins as soon as that water heads down the drain.
“(Wastewater treatment) is actually very similar to water treatment,” said Williams City Manager Skylor Miller. “It goes through a similar treatment process but it is a biological process instead of a chemical process.”
The Environmental Protection Agency (EPA) and the Arizona Department of Environmental Quality (ADEQ) not only regulate the water that goes into public systems, but they also regulate what leaves that system and returns to the environment.
Like the Safe Drinking Water Act, which was established to protect the quality of drinking water in the U.S., the Clean Water Act establishes the basic structure for regulating discharges of pollutants into the waters of the United States and regulating quality standards for surface waters.
In most states, local sewage plants receive discharge permits from state agencies. The treatment plants, must protect the health and welfare of the local population by ensuring that wastewater does not contaminate the local potable water supply, nor violate additional water quality standards that protect the ecological health of the water body.
In 2008, Williams spent 12.8 million dollars to renovate the wastewater treatment plant, which had not received any renovations since the 1940s.
The new plant nearly doubled the city’s wastewater treatment capacity to almost 1 million gallons a day. The plant is designed to remove pollutants from wastewater so the treated effluent can be used to irrigate the nearby Elephant Rocks Golf Course or be safely discharged into Cataract Creek.
Williams’ previous wastewater treatment plant had two man-made, aerated lagoons.
The new wastewater plant meets the Class B+ effluent requirement for reclaimed water. Under Class B+ water quality effluent limitations, secondary treatment, disinfection and nitrogen removal are required.
“Class B+ means it is safe for human contact,” Miller said.
For the past seven years, treated effluent has been pumped to Elephant Rocks to irrigate the golf course greens. During the summer months almost all of the effluent is directed to the golf course.
“In the peak of summer we try to send as much wastewater to the golf course as possible,” Miller said. “In winter we don’t need the effluent, so it is released into Cataract Creek.”
The plant has a permit through ADEQ and the effluent released into the creek is regulated by strict EPA guidelines.
Water that is used in a home or business is flushed through a building’s pipes before it reaches local sewers which are owned by the city. These pipes transport the wastewater by gravity to the wastewater treatment plant just off of Airport Road.
The wastewater system in Williams also accommodates storm drains that are diverted to the same system.
Once the storm water and sewage reaches the wastewater plant, the first screening is at the headworks building where large objects such as plastic bags, baby wipes, feminine products, prophylactics and other large non-biodegradable products are trapped.
The wastewater then flows into the oxidation ditch where raw sewage with solid organics are digested by microorganisms and settle out as a mixture of sludge and water.
Secondary treatment begins when oxygen is added to the wastewater to speed up the growth of the microorganisms. These microbes then consume the wastes and settle to the bottom of the settling tanks. After this treatment, 80 to 90 percent of human waste and other solids have been removed. A significant portion of toxic chemicals are also removed by this process.
“We call them bugs, but there are just billions and billions of bacteria in there that are just eating each other up. They are splitting and reproducing, or really bifurcating,” said Wastewater Treatment Plant operator Pat Carpenter.
Carpenter said the plant constantly monitors the effluent going through the plant and adjusts the microbes based on the results.
“So depending on how much material is coming through, I can activate or deactivate the bugs by either oxygenating or starving them,” he said.
The remaining wastewater is then disinfected with chlorine and then dechlorinated before it is discharged to the golf course or Cataract Creek.
Remaining inert solids are removed from the process via a belt press, which removes most liquids and the remaining spoils are taken to the local landfill.
Carpenter said heavy snow storms can significantly affect the processing at the wastewater plant.
“All the gutters in the downtown are tapped to connect into the wastewater, so when we get all the rain and snow, it is added to the flow rate coming through,” Miller said.
“The bugs get flushed out,” Carpenter added.
Carpenter said he and city staff are working to get approval to reuse the old effluent ponds to store wastewater for future use at the golf course.
“The collection ponds are going to get cleaned up this spring and with ADEQ approval we’re going to store around 12 million gallons here in the summer so we will always have extra,” City Councilman Bernie Hiemenz said.
Editors note: In the William News March 8 edition, the article about water treatment incorrectly stated the amount of water currently stored in the reservoirs around Williams. Currently the reservoirs are holding approximately 850 million gallons of water.