When a landfill’s life is over, the land’s life goes on. And when there’s a plan in place for the landfill site’s next use, the landfill operator is usually at the center of the sometimes-complicated effort to prepare the location for that purpose.
There’s an identified use for a landfill before closure in roughly half the cases, says William Schubert, Houston-based Waste Management Inc.’s senior director for the company’s closed sites management group. One of the most important points for future development, he says, is to not wait until the end to decide. “The earlier you can identify the end use the better off you are.”
For example, it’s easier to shape the landfill into the form needed as it is being built. “Trying to do it all with additional soil at the end of the job, you sometimes get settlement problems that make for more trouble,” he says.
Jeremy Morris, senior engineer with Geosyntec Consultants Inc. in Columbia, Md., has seen a trend toward more sustainable landfill closures, compatible with the surrounding terrain, a break from the traditional tendency to cap a landfill and walk away. “In a traditional Subtitle D closure your reuse options will be rather limited,” he says. “If you can move to a more sustainable type of approach you open up a broader range of reuse opportunities. And you should be able to reduce to amount of care needed because site is more compatible with surroundings.”
That long-range vision can involve not only the design of the closure system but also proactively trying to degrade the waste more than it might be in a traditional landfill. Morris advocates design that allows for a transition to passive landfill management, such as a gravity flow for leachate rather than pumping. “Basically you design control systems and envision end-use conditions that minimize the need to restrict land use,” he says.
And sometimes the intended use of a landfill changes in the process. “It takes decades to finish some of these landfills,” Schubert says. “During that time the attitudes and needs of the public planning bodies changes.”