We all understand the need for garbage can lids. They keep unpleasant whiffs of waste from reaching us. Simple. But, if you're dealing with a collection of radioactive waste canisters, or maybe a huge municipal landfill, putting the lid on garbage can become a bit more problematic.

Dr. Glenn Wilson from DRI's Water Resources Center knows that garbage can lids can be much more sophisticated that the plastic cover we put on our weekly trash. Wilson conducts waste management research at the Department of Energy's Nevada Test Site in southern Nevada, and part of his job is to evaluate landfill cover designs. In semiarid regions the final layer atop a carefully designed waste site, a landfill cover should ideally mimic the natural landscape. It must also take into account rainfall, flooding, soil erosion, drainage, vegetation, and the possibility of burrowing animals--anything at all that might eventually breach the barrier between our waste and the larger world. Of particular concern is separation of waste from water supplies. Not surprisingly, the factors affecting these barriers vary greatly from waste site to waste site. What works well in Louisiana probably won't work as well in Nevada.

Most existing designs for landfill covers were developed for humid areas, where heavy rainfall is a primary concern. A traditional landfill cover designed for a wet area would be highly engineered and, therefore, expensive. It might include a layer of compacted clay (probably hauled in at considerable expense) and a geosynthetic barrier (a costly plastic liner). In wet climates, these underground barriers lead to a lot of pooled water on the subsurface, creating the need for extensive drainage systems. Things are different in the arid West, explains Wilson. "An alternative cover design is based on the natural processes of soil-water storage and plant water use. Precipitation is so low here that the soil can easily store the water until plants can remove it."

With that in mind, Wilson, and fellow DRI researcher Bill Albright, put together a proposal for creating a network of testing facilities throughout the West where various cover options--suited to different environments--could be evaluated and refined. With additional guidance from Pacific Northwest National Laboratory's Glendon Gee (one of the foremost experts in arid landfill covers), the proposal won the backing of the Environmental Protection Agency (EPA). The Alternative Cover Assessment Program, or ACAP, was born. There were, however, several flattering caveats. Instead of a western network, EPA wanted a national one. And the agency also added the task of evaluating the mathematical models currently being used to predict landfill performance.

In the first phase of the program, currently underway, Albright is putting together the actual network of testing sites, reviewing locations and their geology, climate, and available instrumentation. Wilson is busy conducting a similar review of the mathematical models to determine which ones are being used, what processes they incorporate, and their strengths and weaknesses. "Some might be very good for predicting drainage," explains Wilson, "but don't incorporate plant communities or don't take into account snow melt behavior." His investigations should help users determine which models are best for a particular site. Phase two of the program will begin later this year and will include the creation of a Cooperative Research and Development Agreement (CRADA) to team private industry and municipalities with federal agencies like the EPA to fund the development of the new testing sites.

And why would private industry or local government want to toss their money onto a garbage heap? To save itself a bundle. Consider the example of Glendale, Arizona, where the city agreed to finance and build a test facility at a nearby landfill. A traditional cover, with its highly engineered layering, could set the city back as much as $80 million. An alternative cover design, based on the natural processes of the desert environment, could be as low as a mere $8 million.

Obviously, savings like those mean a lot of people are interested in ACAP and what it can do to widen the use of such alternate covers. That fact was apparent at a conference held in DRI's Southern Nevada Science Center earlier this year. The conference brought together 80 representatives from various sectors of the waste world, including the municipal waste industry, EPA's Superfund program, and the Bureau of Land Management--one of the nation's largest owners of landfills. They met to discuss current problems with landfills and their covers and how ACAP could help solve those problems. Wilson and Albright are clearly excited about tackling these issues, and they believe the program has the players to do just that. "We've built a great team of researchers as well as industry people across the country."

Like it or not, our waste is our responsibility. The research team brings us a step closer to dealing with that responsibility in a way that is safe, cost effective, and environmentally sensitive. Something to think about the next time you put the lid on the garbage can.

Jackie Allen