Wastewater Resource Recovery

Wastewater Treatment Division (WTD)

Reclaimed water volumes met

About this performance measure: This measure tracks the amount of wastewater that DNRP's Wastewater Treatment Division converts into resource—reclaimed water.

2009 Results: 309.5 Million Gallons (MG)/year

2009 Target: >260 MG/yr

2010 Target: >260 MG/yr

Influencing factors: Both WTD treatment plants continue to reclaim all water needed for their own operations and any needed by customers. South Plant continued to use reclaimed water for nearly all their compatible internal process needs and irrigation demand. This accounted for about 95% of all reclaimed water used in 2009.

Strategy going forward: WTD's success in converting wastewater into a resource will depend on the cost of providing treatment and conveyance for reclaimed water relative to the cost of using existing sources and/or providing new sources of surface and groundwater. WTD will be developing a regional water supply plan that will address the role of reclaimed water in meeting the region's diverse water supply needs.

Biosolids reuse targets met

About this performance measure: This measure represents WTD's ability to market and recycle biosolids, a nutrient-rich organic material produced by treating wastewater solids.

2009 Results: 100 percent

2009 Target: 100 percent

2010 Target: 100 percent

Influencing factors: Two projects at West Point Treatment Plant to improve biosolids quality and reduce digester problems are in the planning stages. These projects will help WTD maintain 100 percent reuse of biosolids. Although 100 percent of available biosolids were reused, the measure requires ongoing attention to ensure this high rate. Having reliable year-round application and storage sites will have the greatest impact on this measure.

Strategy going forward: WTD's strategy for continuing to meet the target of 100 percent biosolids reuse has several components that include:

• Ensuring availability of proven, reliable reuse sites and customers for 150 percent of biosolids production.
• Securing a short-term emergency storage site for occasional winter use.
• Continuing an aggressive industrial pretreatment program to maintain current low metals levels.
• Maintaining an active research and demonstration program that responds to current issues and questions and evaluates potential new uses for biosolids.

Biogas Recovered for Reuse

About this performance measure: This measure represents WTD's ability to convert biogas (carbon dioxide and methane gas), which are natural byproducts of the wastewater treatment process, into heat and energy for use inside the treatment plants through a process known as cogeneration. WTD aims to capture and reuse at least 75% of available biogas for energy and heat production.

2009 Results: 63 percent

2009 Target: >75 percent

2010 Target: >75 percent

Influencing factors: The percentage of biogas being recycled at the two treatment plants has declined over the past five years due to aging and off-line cogeneration facilities. Construction of a new Waste-2-Energy project at West Point (2010-2011) will bring new cogeneration facilities online by 2012 that will allow greater utilization of the available digester gas.

Strategy going forward: The Waste-2-Energy project underway at the West Point Treatment Plant will harness digester gas, a renewable or "green" source of energy, as fuel for cogeneration facilities to provide heat and power at the plant. King County is committed to recovering and reusing the products of the wastewater treatment process at its regional clean-water facilities. The capability to beneficially reuse products increases the efficiency of the wastewater treatment plants, offers environmental sustainability and saves the ratepayers money.

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