The King County Department of Natural Resources and Parks, Solid Waste Division (SWD) is responsible for processing nearly 1 million tons of mixed municipal solid waste (MSW), organics, recyclables and household hazardous waste each year. The SWD’s core mission is to ensure that citizens have access to safe, reliable, efficient, environmentally sound and affordable solid waste handling and disposal services. To continue this mission, the county is constructing a new 2,500 ton-per-day solid waste transfer and recycling station with a strong focus on material diversion.  

The new Bow Lake Recycling and Transfer Station will replace an existing maceration pit-type facility that opened in 1977 on an old landfill in Tukwila, Wash., about 10 miles south of Seattle. The center point of the 25-acre facility is the 70,000-square-foot transfer building seen in Figure 1.

Background

King County, which is slightly larger than the state of Delaware but with a population around 1.93 million, is a mixture of urban, suburban and rural communities. The county is the 14th most populous county in the country, ranks in the top 50 U.S. counties in per capita income and has a median household income of around $67,700 according to 2009 U.S. Census Bureau data.

The SWD serves unincorporated areas and 37 cities (not including Seattle and Milton, Wash.) through inter-local agreements and is undergoing a large capital improvement process that reflects a lengthy collaborative planning effort between the county and the cities.

The solid waste system in King County is a long-standing partnership between the county and the private solid waste industry (see Figure 2). The county owns and operates eight transfer stations, two public convenience centers (drop box facilities) and the 940-acre Cedar Hills Regional Landfill. The county also operates a fleet of 56 trucks and 150 trailers that haul MSW to the landfill.

As new transfer stations are brought on-line, this fleet will also haul organics to privately operated processing facilities. Only a few of the eight stations currently have the capability to separately receive organics. Private firms provide curbside and business collection of MSW, organics (yard and food wastes), construction and demolition (C&D) debris, and recyclables and own and operate facilities for processing, transfer, and disposal, as well as C&D recovery, recyclable materials recovery and composting.

Reflecting its status as one of the larger counties in the country, the SWD processes a significant amount of waste throughout the year. In 2009, the following approximate quantities of materials passed through the county and private systems:

• 866,000 tons of MSW
• 252,00 tons of organics, including yard waste, food waste and compostable paper
• 620,000 tons of recyclable materials
• 235,000 tons of C&D materials
• 1,500 tons of moderate risk waste