Proposal Title

SESSION 2.2: New Trends in Landfill Gas Collection Practices

Presentation Type

Individual paper

Location

IB 1010

Start Date

4-5-2019 10:45 AM

End Date

4-5-2019 12:15 PM

Disciplines

Aerodynamics and Fluid Mechanics | Environmental Engineering | Non-linear Dynamics | Numerical Analysis and Computation | Ordinary Differential Equations and Applied Dynamics | Partial Differential Equations

Abstract

Landfills form a significant link in waste management throughout British Columbia and accommodate the disposal of municipal, organic, demolition, construction and land clearing refuse. In the past five years we have partnered with GNH Consulting Ltd., a landfill design and operation company in Delta, BC, in order to further the understanding of landfill gas flow regimes and improve engineering practices in landfill operation. This talk will share our work along two directions: horizontal wells and network collection. Horizontal wells are a gas collection mechanism consisting of perforated pipes placed within the waste layer and connected to a suction system. From an engineering point of view they had been expected to function more efficiently than the traditionally designed vertical wells due to collection along the entire length of the pipe, however were found to exhibit baffling behaviour and their popularity was on the wane. They have recently come back into use, although the flow field around them and adequate flow control strategies are still poorly understood. We study the physics of gas flow in these wells with a focus on relations between direct waste properties such as fragment size, packing density and gas generation rate, and geotechnical characteristics of the surrounding soils. This allows us to understand how the collection can be made efficient in different circumstances. We use mathematics and computational fluid dynamics to suggest design and operation strategies: optimise perforation density; minimise suction strength; ascertain gas does not accummulate within the landfill or escape the site; optimise placement of adjacent or stacked wells. Wells of different types form a collection network. We will discuss the reasons why no commercial software solving network flow is suitable for a landfill and present our custom software, including a graphical user interface, that allows to run a simulation of the system for numerous parameter values, test sensitivity, capacity and expected production, optimise configurations and predict bottlenecks.

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May 4th, 10:45 AM May 4th, 12:15 PM

SESSION 2.2: New Trends in Landfill Gas Collection Practices

IB 1010

Landfills form a significant link in waste management throughout British Columbia and accommodate the disposal of municipal, organic, demolition, construction and land clearing refuse. In the past five years we have partnered with GNH Consulting Ltd., a landfill design and operation company in Delta, BC, in order to further the understanding of landfill gas flow regimes and improve engineering practices in landfill operation. This talk will share our work along two directions: horizontal wells and network collection. Horizontal wells are a gas collection mechanism consisting of perforated pipes placed within the waste layer and connected to a suction system. From an engineering point of view they had been expected to function more efficiently than the traditionally designed vertical wells due to collection along the entire length of the pipe, however were found to exhibit baffling behaviour and their popularity was on the wane. They have recently come back into use, although the flow field around them and adequate flow control strategies are still poorly understood. We study the physics of gas flow in these wells with a focus on relations between direct waste properties such as fragment size, packing density and gas generation rate, and geotechnical characteristics of the surrounding soils. This allows us to understand how the collection can be made efficient in different circumstances. We use mathematics and computational fluid dynamics to suggest design and operation strategies: optimise perforation density; minimise suction strength; ascertain gas does not accummulate within the landfill or escape the site; optimise placement of adjacent or stacked wells. Wells of different types form a collection network. We will discuss the reasons why no commercial software solving network flow is suitable for a landfill and present our custom software, including a graphical user interface, that allows to run a simulation of the system for numerous parameter values, test sensitivity, capacity and expected production, optimise configurations and predict bottlenecks.