Q: How do modern landfills protect the environment?
A: The purpose of solid waste management is to remove wastes from living areas in a way that protects human health and the environment. Landfills fulfill this mission by sealing wastes away from the surrounding environment with liners and keeping them covered by more than six inches of dirt.
By sealing in wastes, landfills also control biodegradation, limiting the risk of explosive methane emissions. Uncontrolled biodegradation could also result in a toxic sludge that, if leaked, would endanger groundwater supplies. Modern landfills almost "mummify" waste. Recent landfill excavations have turned up 35-year-old newspapers that were still perfectly legible and 15-year-old corn that was still recognizable.
Q: Can degradable plastics solve the solid waste problem?
A: Because landfills are designed to limit degradation, degradable materials of any type are not likely to affect the amount of landfill space available. Likewise, degradability provides no benefit in the areas of recycling and waste-to-energy incineration.
In areas where composting or wastewater treatment is available as a solid waste disposal option, however, new degradable plastics may prove effective. Composting plastics and paper waste with other organic compostable materials like yard waste, food and agricultural waste creates a valuable soil supplement and contributes to improved farming and gardening efficiency. Flushable, biodegradable products are readily treated in a regulated wastewater and sewage treatment facility, reducing the impact on other disposal systems.
Q: Are we running out of safe places to put landfills?
A: No. While the total number of landfills is decreasing, total landfill capacity is actually increasing. It appears that the trend in solid waste management is to operate fewer, but larger and safer, landfills. For example, in 1988, 70 percent of the country's landfills (the smaller ones) handled less than 5 percent of the MSW that was landfilled nationwide. Fewer than 500 landfills (the bigger ones), or 8 percent of the total, handled about 75 percent of the landfilled MSW.
Q: Why are so many landfills being closed?
A: Landfills are closed when they fail to meet strict regulatory requirements or simply because they are full. Many of the "landfills" most recently shut down were small, poorly run and inefficient or were actually open dumps closed for environmental reasons.
Contrary to popular belief, landfills are designed to minimize and control biodegradation. If they weren't, the uncontrolled biodegradation of such large quantities of waste could create explosive gases and toxic leachate, a threat to our groundwater supplies.