The requirement to manage leachate and rubbish heap gas will continue till the wastes contained inside a site don't have the potential to cause issues in their express location. In fact the pressure to maximize landfill gas and so improve the amount energy obtained from waste is bound to continue to rise.
This fact is emphasized by the Waste Rules and Environment Agency Allowing requirements, with dump operators being legally required to introduce and maintain long term aftercare regimes which, in the case of rubbish heap gas control and leachate management, may need to continue for many decades.
The period of time necessary for a dump to reach environmental stability is much related to the character of the wastes and the rate of the decomposition processes at work within the body of wastes.
It is a recognized fact the rate of stabilization can be maximized by raising the moisture content of the dump, but this is hard to do without permitting an area of saturation to develop within the landfill. This may result in several metres of leachate being allowed to develop above the basal liner.
Such an approach has serious benefits since it is much more likely that stable, methanogenic conditions can be established at an early stage, recirculation of leachate is formed simpler, and the techniques of leachate stabilization and dump gas production can be better controlled.
This conflict, which is a real one and not just unproven, must be addressed by the dump industry.
As the industry moves towards the theorem of "Bio-reactor" landfills it is necessary that the need to control the complex processes at work within the dump - especially in respect of leachate management and gas enhancement - doesn't finally conflict with, and so bias, the necessity to maintain the integrity of the engineered structure. This highlights the requirement for the rubbish heap scientist to work closely with the landfill engineer to reach an OK degree of compatibility.
At the end of the day the principal aim should be the protection of the environment. There's no reason why, with careful design, this target shouldn't be achieved while at the same time improving the benefit to be gained from picking up and harnessing a handy resource in the form of rubbish heap gas.
Leachate recirculation has amazing benefits by reducing the strength of the leachate, especially with a very young leachate where the free-of-charge anaerobic digestion it receives in such a rubbish heap as it bubbles thru the saturated layers is excellent pre-treatment.
Of course to achieve recirculation one basically has to have, if you like, a reservoir to pull on within the base of the dump and therefore by definition one would have some standing leachate level there to tug on. The other point naturally is another, in a way, problem that is that of the hydraulics of heavily compacted waste at the base of a dump, which is truly attempting to get water to pass thru such waste in a controlled demeanour is a hard one which neither the industry or its regulators have got to grips with yet.
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