Rainwater and surface runoff that seeps through landfill waste creates a leachate of water, dissolved waste, and particulate matter. The leachate is collected and temporarily stored in a holding lagoon to isolate it from groundwater supplies.
Traditionally, landfill owners have disposed of leachate by hauling it offsite to a wastewater treatment plant or by spraying it on forage crop land. Both methods have disadvantages. Weekly truck hauling is expensive and adds to highway pollution. As well, impurities are allowed to enter the food chain when forage crops are sprayed with the leachate and livestock then consume it.
Deep-rooted poplar trees and soil provide natural treatment for large volumes of leachate. The fast-growing poplars at landfills dispose of a larger percentages of leachate than they could by using forage crop applications. The method offers the added advantage of preventing leachate constituents from entering the food chain.
A landfill’s use of natural elements in the environment to manage landfill waste will add to its revenues while cutting operating costs. Equally important, phytoremediation will provide a net gain to the community by reducing the odors normally associated with landfill operations and by establishing a small forest that contributes both aesthetically and ecologically to the surrounding areas. Since the poplars are irrigated with drop irrigation, the smell normally associated with spraying forage crops is almost completely negated due to the contaminated water not being spread via large high pressure sprinklers.
Armstrong Landfill, the holding pond can be seen with the Poplar plantation at bottom left.