Investigating Effects of Landfill Soil Gases on Landfill Elevated Subsurface Temperature

Abstract

Subsurface temperature is a critical indicator for the identification of the risk associated with subsurface fire hazards in landfills. Most operational landfills in the United States (US) have experienced exothermic reactions in their subsurface. The subsurface landfill area is composed of various gases generated from chemical reactions inside the landfills. Federal laws in the US mandate the monitoring of gases in landfills to prevent hazardous events such as landfill fire breakouts. There are insufficient investigations conducted to identify the causes of landfill fire hazards. The objective of this research is to develop a methodological approach to this issue. In this study, the relationship was investigated between the subsurface elevated temperature (SET) and soil gases (i.e., methane, carbon dioxide, carbon monoxide, nitrogen, and oxygen) with the greatest influence in landfills. The significance level of the effect of soil gases on the SET was assessed using a decision tree approach. A naïve Bayes technique for conditional probability was implemented to investigate how different gas combinations can affect different temperature ranges with respect to the safe and unsafe states of these gases. The results indicate that methane and carbon dioxide gases are strongly associated with SETs. Among sixteen possible gas combinations, three were identified as the most probable predictors of SETs. A three-step risk assessment framework is proposed to identify the risk of landfill fire incidents. The key findings of this research could be beneficial to landfill authorities and better ensure the safety of the community health and environment.

Detection and extinguishment approaches for municipal solid waste landfill fires: A mini review

“…A badly operated active gas extraction system or a poorly-designed leachate recirculation system is likely to allow air into the waste mass (Copping et al, 2007) which promotes the fire at landfill sub-surface. Several studies (Needham et al, 2003; Sabrin et al, 2020; Stearns and Petoyan, 1984) were carried out on temperature monitoring for the Hanover landfill which was under operation during 1936–1980. It was reported that the temperature increased up to 30 m depth from landfill surface and then it decreased towards the base.…”

“…Gases like CO, O 2 , CH 4 and CO 2 were determined by inserting steel probes around the landfills and through the gas extraction wells (Department of Environmental Management, 2008). Sabrin et al (2020) investigated relationship between the sub-surface elevated temperature (SET) and landfill gases (i.e. CH 4 , CO 2 , CO, nitrogen (N) and oxygen).…”

“…General extinguishment methods. Extinguishing a landfill fire by covering the burning masses and thereby limiting the oxygen availability for the chain reaction is reported to be less efficient Sabrin et al (2020). (Ettala et al, 1996), even though this can limit the intensity of the waste fire (Sperling and Henderson, 2001).…”

4D Models Generated with UAV Photogrammetry for Landfill Monitoring Thermal Control of Municipal Solid Waste (MSW) Landfills

“…The gas generated by the decomposition of organic matter is called biogas or landfill gas (LFG). It is composed of 45-60% methane (CH 4 ), 40-60% carbon dioxide (CO 2 ), 2-5% nitrogen (N2), 0.1-1% oxygen (O 2 ), and other gas fractions in lower percentages, including ammonia (NH 3 ), carbon monoxide (CO), hydrogen (H), sulfides, and non-methane organic compounds (NMOC) such as benzene, vinyl chloride, and trichloroethylene [10].…”

“…The accumulated heat from exothermic reactions and the volatility of the gases generated make landfills prone to surface fires and the slow-burning of MSW below [10]. High temperatures affect the proper functioning of landfills, influencing gas generation, leachate quality, slope stability, and landfill integrity, and may also affect human health and the environment due to gas emissions into the atmosphere and the release of incomplete combustion products as a result of fires [17,18].…”