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Sustainability and equity

Sustainability and equity

South Treatment Plant

Learn about sustainability and equity initiatives at South Plant and our commitment to being a good neighbor and having a positive impact on our community.

FLUSH FACT: In 2021, South Plant produced and sold 2.63 million therms of methane gas, harnessed during the treatment process.

Being a steward of the environment goes hand in hand with being a good neighbor. For years, South Plant has been making choices that advance equity and sustainability and seek to deepen our connections with the community that we serve.

A basket of produce harvested from City Soil Farm. Harvested produce from CitySoil Farm.

Contact us

24 hour emergency and odor reporting:   206-263-1760
Administration:  206-263-1810

1200 Monster Road S.W.
Renton, WA 98057

Directions and map

Read more about our programs at South Plant that advance equity and protect the environment:  

CitySoil Farm

CitySoil Farm is a unique, 1.5-acre demonstration farm located in a once unused area of the South Plant grounds. The farm serves to cultivate food gardeners and to address food injustice for neighboring communities by providing fresh, local produce accessible to everyone. The farm also uses recycled water and compost made from Loop biosolids. Every year we partner with White Center Food Bank to grow and provide culturally relevant produce (up to over 5,500 pounds) to the community.

WaterWorks Gardens

Waterworks Gardens is a public park next to South Plant that filters and cleans stormwater from the treatment plant’s 50 acres of roads, parking lots and hard surfaces. Once stormwater passes through the garden, it flows into Springbrook Creek.

Biogas reuse and heat 

During the treatment process, human waste produces a lot of methane gas (or biogas). South Plant sells all its biogas on the renewable market and then purchases natural gas, at a lower cost, to heat its facilities. Those funds then go back into maintaining the wastewater system, capital projects, and equity and social justice work.

Loop® compost pilot

Loop® is a fertilizer alternative produced by cleaning, recycling, and transforming King County’s wastewater into biosolids. Currently, Loop fertilizer is a Class B biosolid, meaning that it can only be used on agricultural and forestlands. South Plant is starting an exciting pilot program to produce Class A biosolids which can be taken home by community members to use in their home gardens. Check out this video on how Loop is made.

Recycled water

We use recycled water in a variety of ways at South Plant. We use it for cooling our equipment and watering plants on our grounds, including watering CitySoil Farm. We have a partnership with Starfire Sports complex to provide recycled water (water that is held to a very high standard of cleanliness) to water the sports fields at their facility. CitySoil farm also uses recycled water from South Plant.

Two hands holding Loop® BiosolidsA handful of Loop® Biosolids

Three jars displaying raw sewage (cloudy with floating particulates), plant effluent (somewhat cloudy) and reclaimed water (clear). The difference between the water that comes into South Plant and the water that leaves

A view of the "Groto" at Waterworks Parks, an area with pillars and tilework. Waterworks Gardens