LOTT study: Reclaimed water safe to use

LOTT Environmental Planning and Communications director Lisa Dennis-Perez said reclaimed water has a low risk to human health and no threat to ecological health.

Dennis-Perez updated Olympia city council members on the LOTT Clean Water Alliance-sponsored reclaimed water infiltration study yesterday.

LOTT's long-range plan includes treating wastewater as a resource and using reclaimed water for groundwater replenishment and reuse.

Matt Kennelly, assistant executive director for LOTT, said they have conducted an extensive multi-year study of the infiltration of reclaimed water into groundwater. "The goal is to provide local scientific data and community perspectives to help policymakers make informed decisions about future reclaimed water treatment and uses."

"Out of that wastewater resource management plan, we set out to build reclaim water plants: Budd Inlet Reclaimed Water Plant, which treats about 13 million gallons per day of wastewater; Martin Way Reclaimed Water Plant, and Hawks Prairie Recharge Basins," he said. 

The primary use of water from the Budd Inlet (downtown)  facility includes irrigation of parks and other public spaces. It sends the flow to the Tumwater tank to irrigate the golf course, which needs about 600,000 gallons of water per day.

Kennelly said there had been questions about from community members about residual chemicals in reclaimed water.

He explained that residual chemicals are those medicines, household products, personal care products, and things at homes that eventually make their way into the wastewater stream that comes down to LOTT water treatment.

"We looked very deeply at these residual chemicals in our environment," Kennelly said.

Summary findings

Dennis-Perez said the study focused on a primary question about the risks from infiltrating reclaimed water into groundwater because of chemicals that may remain in the water.

According to Dennis-Perez, the water is safe to use and the peer review panel also agreed with the findings.

Other findings include:

• Residual chemicals are found in our environment – in areas where reclaimed water is used for infiltration and also in areas where reclaimed water is not used for that purpose
• Residual chemicals from infiltration decrease with time and distance as water moves away from the site
• Risk assessment experts found very low risk to human health and no risk to ecological health

"We had multiple layers of input and review and oversight to make sure that this is a rigorous scientific research effort," she said, adding they have been working on the study for about 10 years.

Among the study activities they did was identifying a list of residual chemicals for testing. They narrowed the list to 134 chemicals for testing and used tracers to follow reclaimed water underground after it was infiltrated at Hawks Prairie Recharge Basin.

They also established a monitoring well network and tested wastewater reclaimed water, surface water and groundwater for residual chemicals.

Dennies-Perez said they also created a computer model to estimate conditions 100 years into the future.

“We looked into the future. The risk associated with conditions 100 years into the future is very low. So when we say the current risk is low, we mean based on the current study and the information that we have at this time. Looking forward, even 100 years into the future, the risk is identified as low,” she added.

The scientific research group was composed of:

• project team from LOTT staff and engineering and sub-consultants with specialized expertise;
• community advisory group consisting of local citizens came from diverse background;
• science task force composed of technical experts from Olympia, Thurston County, State Department of Health, Department of Ecology and Squaxin Island tribe; and
• independent peer review panel consisting of national experts from a variety of technical fields

She said the peer review panel and the science task force group had been involved in reviewing all of the planned work, results from each part of the study and the technical reports.

"The community advisory group has been invaluable in helping to ensure that we are asking the right questions and addressing community concerns," Dennis-Perez said of the community group involvement.

Recommendations

LOTT's proposed approach includes continuing use of reclaimed water infiltration but would like to conduct additional targeted monitoring to watch some of the chemicals of interest that were identified as part of the study, Dennis-Perez said.

She also recommended reevaluating if there is a need for advanced treatment in the future and conducting sampling to pinpoint potential sources of chemicals. "That information may help us identify ways to reduce inputs of chemicals into the wastewater system."

Dennis-Perez said LOTT is expecting new regulations, particularly around PFAS chemicals, at both the state and the federal level.

PFAS or Perfluoroalkyl and Polyflouroalkyl Substances are chemicals used to make various everyday products.

"Within the next few years, we know that the chemical landscape will continue to change. Products may be phased out, additional products are always coming on the market. It will be important to keep tabs on new information and update the study over time," she said.

LOTT will share the study with the community at a virtual meeting they plan to hold on Aug. 15, 2022 and an online open house in mid-August and to mid-September.