West Point Treatment Plant As part of WTD’s mission to protect public health and the environment, WTD constantly works to maintain and improve its facilities and insure safe, reliable service. At the county’s treatment plants, inspection, maintenance, and repair projects occur routinely. Several projects are planned for West Point Treatment Plant to improve plant efficiency and operations and insure compliance with regulations. The West Point Treatment Plant treats on average 100 million gallons of wastewater each day. After removing trash and dirt and biologically treating the water to remove organic solids, the treated wastewater must be disinfected to kill bacteria and pathogens. Currently, chlorine gas is used to disinfect. To increase system reliability King County will install a disinfection system that uses a sodium hypochlorite solution instead of chlorine gas. Sodium hypochlorite is a safer product than chlorine gas and is similar to household liquid bleach. In 2009, a back up system delivering sodium hypochlorite was installed to prevent disinfection failures like those experienced with the current system. In 2010, the county plans to install a sodium hypochlorite system and the chlorine gas system will be decommissioned. Back to top of page. 
When wastewater arrives at the West Point Treatment Plant, it is screened to remove large materials from the influent such as rocks and sticks, as well as "manufactured items" like plastics, metals, and ceramics.
When wastewater arrives at the West Point Treatment Plant, it is screened to remove large materials from the influent such as rocks and sticks, as well as "manufactured items" like plastics, metals, and ceramics. These items get in the system by inappropriate disposal or flushing into the storm system. Unfortunately, many of the smaller manufactured materials pass through the screens and are not broken down during the solids treatment process. Instead, they then end up in treated biosolids where they become an aesthetic nuisance and contribute litter to forests and agricultural lands where the biosolids are applied as soil amendments and fertilizer. In 2007, the Washington State Department of Ecology introduced new biosolids management regulations aimed at removing significantly more inert material from the biosolids produced at wastewater treatment plants statewide. The regulations require the installation of screens with gaps no larger than 3/8 inch. The screens at King County’s West Point Treatment Plant currently have 5/8-inch gaps, so the county recently started a project to replace them with the smaller 3/8-inch screens. The county will also add new equipment to grind, wash, and compact the large amount of additional material we expect to capture. The county had previously started design on a similar project in 2002 to construct a new screening system at West Point. The design was based on the concept of expanding the existing screenings building, but this approach was found to be prohibitively expensive and potentially unsafe for operators because even with expanding the building, the equipment had to be tightly placed and would be difficult to access for routine maintenance and repairs. The current project is based on the concept of constructing a new building to accommodate the screenings handling equipment in a safe, reliable, and cost effective way. The team expects to complete final design in December 2012 and complete construction of the facility by the spring of 2015. Back to top of page. 
The new cogeneration system will produce about 23,000 megawatts of electricity each year, equivalent to what can power more than 2,300 homes.
King County plans to install waste gas generators to allow on site electricity production. During the treatment process, methane gas is produced by digesters that treat the organic solids captured from wastewater. Right now West Point uses the gas as a fuel source for influent pumps and as a heat supply. The new cogeneration equipment will also allow for the production of electricity. King County is currently seeking bids on the construction contract. We will begin the project in 2010 and begin generating energy from waste in 2012. Using digester gas to run equipment and generate electricity: - recycles a by-product of the wastewater treatment process
- creates a renewable source of energy
- reduces plant dependence on non-renewable energy sources.
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Digesters break down organic solids and scum from wastewater into nutrient-rich biosolids that are safe to be used as a soil amendment.
The solids digestion system at West Point Treatment Plant illustrates how the plant operates efficiently on a small footprint. Digesters break down organic solids and scum from wastewater into nutrient-rich biosolids that are safe to be used as a soil amendment. West Point operates six digesters, rather than the seven originally planned for this facility. Digesters 1-5 were installed in 1963 and 1985, and Digester 6 was added as a blending digester in 1996. The number of digesters has remained the same, despite increased flows over the operating life of the system. In order to continue operations without adding a seventh digester that was originally planned, it is necessary to get peak performance out of all the existing digesters. To accomplish this goal, a project team is planning equipment and controls upgrades to the existing facilities. The final design for this project will be completed in 2010 and implemented in 2012 and 2013. Back to top of page. Treatment plant staff works around the clock to carry out operations, monitor West Section facilities, and meet reporting and compliance requirements. To support productivity and efficiency, a variety of functional working environments are required at West Point. Office space at West Point did not meet these goals. Offices were housed in structures that did not meet current code requirements, requiring staff to be moved. Displaced staff members are currently sharing offices and cubicles with other staff until new office space is constructed in an annex adjacent to the administration building. The proposed office annex will provide code-compliant, functional office space for plant staff, supporting productivity and efficiency goals. The most time- and cost-efficient alternative is a permanent modular building. The office annex will not exceed height limits established in the 1991 settlement agreement. The project team plans to complete design and permitting by May 2011 and construction in late 2011. The existing office trailers, no longer in use, will be removed. Back to top of page.
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