Safe and effective gas recovery by means of a low-technology, integrated site design approach

Abstract

The benefits of landfill gas control are two-fold: hazard or nuisance elimination and revenue generation by energy sales. A large number of schemes has been established, mainly in the U.S.A., but also in Western Europe. For the majority of these projects the aim has been to maximise gas recovery at already completed sites, or sections of sites. Gas recovery plant design has been almost purely “retro-fit” in concept. This approach can be costly both in terms of capital-overspend as well as possible ineffectiveness of gas leakage (or migration) control. Moreover, the “Western” methodology is generally inappropriate to landfills in Eastern European countries owing to the differing characteristics of landfill design such as surface cover placement, division of the site into cells, leachate and surface water collection. However, by considering carefully the special characteristics of these sites and, most significantly, adopting an “integrated design” approach, then energy recovery from landfill gas can be both profitable and environmentally beneficial. The aim of this paper is to identify the key factors which influence landfill gas collection effectiveness and to incorporate these in an overall site design strategy. In this way, the gas collection plant is optimised and linked directly to a specification for the site final cover contour. Simple design procedures are employed and the modelling and analysis aspects are short, concise and readily verifiable. This new methodology is discussed in detail and the design techniques are applied to a “national” Eastern European site.