Modelling the cost-effectiveness of sanitary landfill leachate control systems

Abstract

Leachate leakage is a major risk associated with sanitary and hazardous waste landfills. This paper describes how two simple performance models, time to breakthrough and leachate leakage flux, can be used in conjunction with a cost model to develop cost-effectiveness relationships which can be used to assist the leachate control system design and planning decision-making process, and, thereby, reduce this risk.

Sensitivity and marginal analyses indicate that time to breakthrough (t_b) is most sensitive to liner hydraulic conductivity and thickness and that increasing liner thickness yields increasing marginal returns to fb. Leachate leakage flux (q_L) is sensitive to liner hydraulic conductivity and the leachate collection pipe spacing-liner thickness ratio. For a given pipe spacing, increasing liner thickness yields decreasing marginal returns to q_L.

Hypothetical cost-effectiveness relationships for t_b and q_L are developed analytically and numerically. As a means of introducing the concept of risk, a probability density function for liner hydraulic conductivity is introduced into these relationships.

Keywords:

• decision making
• land fill
• leachate
• containment and collection
• cost effectiveness
• sensitivity analysis
• risk
• probablistic

Additional information

Notes on contributors

P. H. Byer

Paper presented at the Second Canadian Seminar on Systems Theory for the Civil Engineer, Calgary 16-17 May 1984