Land Reclamation
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Biosolids provide nutrients and organic matter to damaged soils, enabling renewed plant growth.

Seeking Solutions
Human activities often disturb native landscapes and underlying soils. Heavy equipment used in construction, utility installation and strip mining can severely damage soil structure by removing topsoils or by pulverizing and compacting soils. Following this damage, soils are often unable to support plant life due to lack of nutrients and organic matter, compaction, altered pH and other ecosystem changes.

Benefits of Biosolids Disturbed soils can be restored and revitalized through the addition of organic matter. Nutrient-rich, organic biosolids replace lost topsoil and improve soil fertility and stability, thus decreasing erosion and aiding in revegetation. Biosolids have been used successfully to reclaim large construction sites, surface strip mines, parks and road cuts; recreate wetlands; and enhance wildlife habitat and conservation areas.

How it Works
Soil improvement and land reclamation projects use onetime or infrequent applications of large quantities of biosolids to increase the amount of nutrients and organic matter in the poor or damaged soil. The nutrients in the biosolids jump-start the immediate growth of plants on the site and provide a pool of nutrients from which the soil can draw to feed the plants on a long-term basis. The organic matter that enters the soil from the biosolids allows the soil to become aerated and replaces lost or compacted topsoil, especially when plowed into the surface of the existing soil. Most nutrients (nitrogen, phosphorus, potassium, sulfur, zinc and boron) will remain in the plant root zone bound to organic matter much longer than would traditional inorganic, commercial fertilizers.

What's Happening

Wildlife habitat enhancement: In 1995, King County's Biosolids Management Program and Seattle Parks and Recreation worked together to enhance wildlife habitat at the popular Discovery Park in Seattle. The agencies cleared nearly 14 acres of Scotch broom and blackberry vines, tilled King County biosolids into the soil and reseeded with grasses and other native plant species. In addition, shrubs and trees were planted and fertilized with composted biosolids to create wildlife corridors. A nearby biosolids park project conducted in the 1980s remains a lush meadow, free of Scotch broom.

Copper mine reclamation: After seeing the results of successful demonstration plots, the Greater Vancouver Regional District in British Columbia has begun using biosolids to reclaim portions of the Similco copper mine near Princeton, B.C. The goal of this project is to revegetate extensive areas of piled rock and mine tailings and stabilize slopes. Tree establishment screening trials through the University of British Columbia are underway here to determine the best species for establishment in reclaimed mine tailings.

Wetlands restoration: As part of a drainage maintenance project, the City of Everett, Washington, restored 1.25 acres of land to its previous wetland characteristics by using biosolids, biosolids compost and yard debris compost. The nutrient-rich organic material provided an excellent growth medium for native wetland plant species, while stabilizing slopes. This successful venture may lead the way for other wetland restoration projects in urban environments.

Road reclamation: The Mountains to Sound Greenway Trust, centered in King County, Washington, is applying GroCo biosolids compost to revegetate logging road scars and landings in the foothills of the Cascade Mountains along the Interstate 90 corridor. The Mountains to Sound Greenway Trust is a public-private partnership dedicated to maintaining a green belt for approximately 100 miles along Interstate 90 from Ellensburg to Seattle.

Final landfill cover reclamation: Cowlitz County, Washington, applies its biosolids to the cover of a nearby closed landfill to promote the growth of vegetation on the landfill site. Tacoma, Washington, also had a very successful project to apply biosolids to grow grass on a landfill cover when hydroseeding had failed.

Gravel pit reclamation: Pierce County Water Resources, Washington, is working with the sand and gravel mine next-door to its treatment facility to establish vegetation on past mining sites. Twenty acres of this site are dedicated to demonstrating the value of Pierce County biosolids as a soil amendment, through forestry, landscaping and rate trial research conducted by the University of Washington College of Forest Resources.

Strip mine reclamation: A large strip mine near Centralia, Washington, used biosolids from a number of cities during the 1970s and 1980s to reclaim disturbed sites. Several hundred acres were amended with biosolids, then planted with tree seedlings.

Golf course establishment: Tacoma and Bremerton, Washington, collaborated to apply Exceptional Quality biosolids to a new golf course, helping enable it to open several months earlier than planned and with better grass vitality.

Copyright © 2004, Northwest Biosolids Management Association
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