HORIZONTAL COLLECTORS: DESIGN PARAMETERS, MATHEMATICAL MODEL, AND CASE STUDY

摘要

Horizontal collectors have been used successfully at many landfills to collect landfill gas (LFG) and are an acceptable method for collecting LFG under the New Source Performance Standards (NSPS) for municipal solid waste (MSW) landfills. Our literature review indicates that the Los Angeles County Sanitation District uses horizontal collectors extensively at its many landfills and first reported on their use in 1982. However, there is a dearth of published design criteria, design details, and performance data related to horizontal collectors that consider all of the critical system parameters. Most of the publications present limited empirical data and anecdotal observations. This paper is intended to advance the industry by providing the design engineer with a theoretical basis for establishing the key system parameters. It presents recommended design criteria, a mathematical model, and a case study. Our mathematical model provides an understanding of radius of influence and its impacts due to other system parameters such as waste permeability, flow rate, and applied vacuum. Combining the theoretical basis with actual test data, the design engineer can develop a practical and cost-effective design for any particular landfill. The case study summarizes our evaluation of a horizontal collector recently installed at a Pennsylvania MSW landfill. Using field data for model calibration, we established parameters such as required well head vacuum, maximum horizontal collector length, and collector spacing.