By Bill Hardesty | [email protected]

On May 18 and 19, a 900-ton crane lifted one of two 160,000-pound covers for anaerobic digesters at the Central Valley Water Reclamation Facility at 800 W. Central Valley Road, which is about 3200 South and 900 West in South Salt Lake City. 

This event is part of a $400 million capital improvement project at the facility covering several years. These improvements have caused sewer fees to increase in recent years. 

“The two reasons for the improvements are to meet new federal and state regulations, and simply things are worn out,” General Manager Phillip Heck said.

In the case of the two anaerobic (meaning no oxygen) digesters built in the 80s, the roofs had started to rust, and the system lost some efficiency.

It took two months to weld the cover.

When the facility was built, it was state-of-the-art, and the capital improvements are intended to bring it back to a state-of-the-art facility.

Central Valley Water Reclamation Facility

The facility serves over 600,000 residents within the area of West Valley to Alta from 2100 South to 7200 South on the West and 9800 South on the East. It was built in the 70s and 80s, allowing individual water entities to close their water treatment plants.

The facility treats 50 to 60 million gallons of wastewater each day. Clean water is returned to the Jordan River. Heck estimates that it takes a drop of water eight to 10 hours from entering the system to joining the Jordan River.

The seven entities that supply wastewater own and control their sewer lines. Their smaller lines discharge into larger pipelines called outfalls. These outfalls connect to the facility’s main outfall line. The facility’s outfall line consists of approximately seven miles. It takes about eight to 10 hours for flow to reach the treatment plant from the most remote regions of the collective areas.

At every entity’s outfall connection is a metering station. Central Valley Water regularly takes samples at these stations. The samples are analyzed for wastewater strength, meaning the biochemical oxygen demand, total suspended solids, and ammonia. This analysis is added to the meter flow data to determine each entity’s monthly billing. Stated much more straightforward, an entity with more wastewater pays more, or an entity with wastewater that will need more treatment pays more. The entity’s billing is part of a person’s or business’s monthly sewer bill, which pays for the entity’s sewer system and treatment and any upgrades at the facility.

Water treatment process

Water treatment is a complicated process with numerous steps. For a complete explanation, go to the Central Valley Water website (www.cvwrf.org/). 

The wastewater comes into the facility about 25 feet down in the ground. It is pumped to the surface. 

The first step for the wastewater is to go through a screening process to remove trash. The wastewater then goes to aerated grit tanks. As the name implies, sand and grit are removed and disposed of at the county landfill.

Wastewater is then pumped to primary clarifiers. These are the large circle tanks that are low to the ground. As the water is turned, solids settle to the bottom of the tank. The solids are pumped into digester tanks. While in these tanks, the solids break down, creating methane gas. One unique aspect of these digesters is that the roof goes up and down depending on the amount of gas. The methane gas is pumped to cogeneration engines.

A different digester is on the east side of the facility. There are two tall white tanks that look like upside-down funnels. They can be seen from the freeway. These tanks capture the same methane gas, but the roof doesn’t move. 

The cogeneration engines are used to power the treatment facility, including providing heat in the winter and air conditioning in the summer. Central Valley Water is hoping in the future to put excess energy into the Rocky Mountain grid.

Meanwhile, the water goes through a series of tanks and clarifiers, allowing beneficial bacteria to consume the remaining fine suspend organic solids from the water. The water is hit with ultraviolet light before entering Mill Creek and onto the Jordan River. 

With the capital improvements, the process will result in cleaner water because the water will be stored for 24+ hours in tanks allowing the bacteria more time to work.