LOTT’s Reclaimed Water Study: What we have learned so far about residual chemicals in our local waters
Wendy Steffensen and Jeff Hansen-
LOTT is a wastewater utility. They receive wastewater from Thurston County, Lacey, Olympia, and Tumwater. They discharge treated water to Budd Inlet. But they have been grappling with how to accommodate growth in the region without increasing discharge to Budd Inlet. The public wanted LOTT to treat wastewater as a resource. So they treat much of their water to reclaimed water “Class A”. They now infiltrate reclaimed water in the Hawk’s Prairie area. LOTT began a reclaimed water infiltration study in 2012. Their objective is to understand what residual chemicals are in the reclaimed water. They are doing a scientific study and keeping the public involved throughout the process.
1. Water quality characterization
2. Treatment Effectiveness Evaluation- Includes soil aquifer treatment by the aquifer.
3. Risk Assessment
4. Cost Benefit Analysis
This part is on 1. The water quality characterization
There are two study areas
1)Hawks Prairie, which has a reclaimed water infiltration site.
2) Henderson area, not infiltration of reclaimed water there.
What is the potential source of residual chemicals?: reclaimed water, septic systems, stormwater…
They sampled 282 residual chemicals and 127 unregulated chemicals.
Most of these unregulated chemicals are in the part per trillion concentration.
That’s one drop in 16 swimming pools!
What’s in the wastewater? Budd inlet and Martin way treatment plants.
About 50% of unregulated chemicals that they looked for were detected in raw wastewater.
Now in reclaimed water:
For four chemicals, treatment removed more than 85% of the chemical.
For 7 chemicals treatment removed 33-85% of the chemical. Example: carbamezapine
For 3 chemicals, there was poor removal- Example- iohexal
Generally chemicals found in groundwater were also found in surface water and in reclaimed water.
The results from this study are similar to other areas of the country.