“…Sampling before or in conjunction with the construction of gas recovery wells or leachate recirculation, especially at sites with limited existing information, may have economic benefits to optimise the gas extraction or liquid recirculation methods. Landfills have been previously sampled to estimate the rate of degradation of MSW and its different waste components (e.g., Hartz and Ham, 1983;Bogner, 1990;Gurijala and Suflita, 1993;Baldwin et al, 1998;Jokela et al, 2002;Gardner et al, 2003) while -to our knowledge -only a few studies have been published on vertical profiles of pH, temperature, moisture, organics, cellulose, lignin, or BMP (Bookter and Ham, 1982;Jones et al, 1983;Attal et al, 1992;Ham et al, 1993;Wang et al, 1994;Townsend et al, 1996;Chen et al, 2004;Ö stman et al, 2006) and even fewer studies (Ettala et al, 1988;Ham et al, 1993;Ö stman et al, 2006) on landfill nitrogen content. These earlier studies showed MSW landfills to be heterogeneous with respect to the stages of degradation and conditions within the landfill body with wastes in the top layers usually less degraded than in the deeper layers.…”