A great deal of the federal and state legislation already noted calls for the use of materials which "biodegrade", including biodegradable plastics. The assumption which underlies such legislation is that if most of the material which goes into a landfill were to decay, a landfill would last longer and, therefore, fewer new landfills would have to be built. As noted above, this argument seems to be based on the notion that if we have to use landfills and if only rapidly decaying materials would be allowed in landfills, a landfill could become what might be called a "perpetual space-making machine."
Fortunately, at least one city which passed legislation banning one form of non-biodegradable packaging material – polystyrene foam food containers – has moved to undo that mandate. City officials in Portland, Oregon, which passed such a ban in 1988, are now acknowledging that bleached paper cups and plates – substitute materials for expanded polystyrene fast food containers – leach dioxin when they decompose whereas expanded polystyrene has no such negative environmental impact. 
The issue faced by Portland officials really begs an answer to the following question: What's so great about having something biodegrade in a landfill? Do we really want material placed in a landfill to decay faster than it would otherwise?
When material decays in a landfill, several relatively mild acids and methane gas are produced. In addition, biodegradation alone yields a moderate amount of moisture. If rainwater is allowed to seep into a landfill, the combination of external and internal moisture could force the internally generated acids into groundwater supplies along with anything else the acids may have dissolved. This is the often-cited "Leachate Problem."
Methane gas is volatile. Indeed it is methane gas which heats our houses and cooks our food. In a landfill, methane gas – along with C02 one of the so-called "Greenhouse Gases" – can migrate through the ground and accumulate in underground pockets or escape into the atmosphere.
Therefore, questions of aesthetics aside, there are only two environmental problems posed by landfills: Leachate and methane gas. Given this, the reason why both EPA and OTA admit that modern landfills need pose no health threat to individuals or the environment is because modern landfills have systems which hold leachate in place as it develops, and remove it directly from the landfill. In addition, modern landfills incorporate systems which remove methane gas and, in many instances, use the gas to provide energy to the buildings used in the landfill operation.
The University of Arizona's Dr. William Rathje knows what goes on in a landfill – even an old landfill – and he's been trying to tell us something. What he has learned by excavating old landfills in climatically diverse parts of the country, landfills which do not meet the tough standards laid down by current EPA regulations, is that virtually nothing happens in a landfill.
A covered landfill is a dry anaerobic environment – an environment without oxygen or moisture. Organic material needs both to decay. Without oxygen and moisture, decay moves at a snail's pace. Therefore, what is put in a landfill tends to stay in the landfill in much the same form it had when first buried. While some decay does occur, it occurs so slowly that even after 30 years in place, it is possible to enter a landfill and find fully intact corn cobs and hot dogs alongside newspapers which announce the election of Dwight D. Eisenhower. 
A landfill – even, as Rathje has discovered, an old landfill – is not a place of massive waste decay with rivers of gushing leachate. It's a place where waste stays, and stays, and stays. Indeed, if decay were to occur at a rapid rate, the opportunity to build atop them would cease to exist. New York City's LaGuardia airport is on a landfill; Newark airport is on a landfill; the large VA hospital in Cincinnati is on a landfill.
The fact that landfilled waste is essentially entombed has caused scientists in some German cities – where land is quite scarce relative to population – to experiment with techniques for pre-treating garbage (all garbage) in open-air compost piles before releasing the material to landfills. The fungi generated in open air broke cellulose chains and allowed the garbage to enter the landfills as a mass of sugar. Decay time in the landfill was reduced by up to twenty-five years. Unfortunately, the open-air compost piles stink so much that neighbors were opposed to this technique for managing solid waste. 
Entombed garbage! If that's what happens in old, non-Subtitle D landfills, what would happen in the new landfills built according to the tough new standards established in Subtutle D of the federal Resource Recovery and Conservation Act? With the tight new standards which apply to modern landfills, MSW in a landfill will become even more benign than it now is in old landfills.
Contrary to much current popular commentary on landfills, waste placed in a modern landfill will stay there. Leachate will be removed and carried away for safe treatment and disposal. Methane gas will be removed and, in some instances, be used to supply energy to the landfill operation. On environmental grounds alone, that is more than enough to make a modern landfill an acceptable waste management alternative.
But what about the cost? Is a landfill economically superior to other waste management alternatives, or economically inferior?
Almost all of the 70 landfills currently operating in Michigan were constructed using containment or liner systems to protect against leachate seepage into groundwater systems. However, only seven currently use the double containment system which is preferable and which will soon be mandated.  What would it cost to assure that all landfills are fully designed with proper liners to provide maximum environmental protection?