Methods of disposing of trash have come a long way since the days when it was common practice to use wetlands as burial sites for garbage. In 1940, a lake located on the North Portland Peninsula near the confluence of the Columbia and Willamette rivers was designated as a landfill. It served as the region’s primary garbage disposal site for the next 50 years.
Now the area is being actively restored into a prairie – providing habitat for coyotes, great blue herons and painted turtles – while Metro continues to manage and monitor the area for future uses.
14 million tons of garbage
The St. Johns Landfill is situated in Metro’s Smith and Bybee Wetlands Natural Area, the largest protected wetland within an American city. By the early 1960s, the former lakebed was filled with garbage to the edge of its surrounding levee. Although the majority of waste in the landfill is domestic solid waste, industrial waste from a pesticide-manufacturing facility was also disposed in the landfill between 1958 and 1962. Metro estimates that up to 14 million tons of waste were disposed in the landfill site during its years of operation.
Covering the waste
In 1980, Metro assumed responsibility for landfilling operations, and in 1990 assumed ownership of the landfill property from the City of Portland, including responsibility for closing the 238-acre site in an environmentally sound manner. From 1991-1996 Metro constructed a $36 million landfill cover system designed to prevent rainwater from leaching contaminants into groundwater, which could carry them into the surrounding soil and waterways, and to control methane gas generated by decomposing waste. A methane gas collection system draws gas from the waste and pipes a portion of it to the Ash Grove Cement Company where it is used as fuel for producing lime. The remaining portion is flared (combusted) at high temperature on site, to destroy or reduce potential environmental contaminants.
Today the former landfill site is recognizable only by methane gas-collection lines that crisscross its grassy surface, and by gas management facilities – including the flaring operation - on a small portion of the site near its entrance.
Since completing the landfill cover in 1996, Metro has spent nearly $20 million on landfill post-closure care such as facilities maintenance, methane gas collection, environmental monitoring, and landscape and streamside restoration. The funding source for these activities is garbage disposal fees.
In 2005, Metro began a remedial investigation of St. Johns Landfill to identify any remaining risks to health and the environment. A final remedial investigation report was submitted to Oregon DEQ in 2012, and a study of feasible measures for controlling risks identified in the RI Report was submitted in 2013. Potential risks are to sediment-dwelling organisms in a small area of Columbia Slough adjacent to the landfill site. The contribution from the landfill to these risks could not be clearly determined. However, Metro is committed to actions that protect human health and the environment, and enhance habitat, consistent with its responsibility for overall management of the Smith and Bybee Wetlands Natural Area. As such, the feasibility study recommends that Metro treat the target sediments with a product containing natural constituents that bind contaminants, thereby reducing the exposure of aquatic organisms to the contaminants. Future uses of the landfill, as described in the Smith and Bybee Comprehensive Natural Resource Plan, are unaffected by these potential risks and the recommended remediation of sediments.