Air Injection Potential of Vertical Wells in an Aerobic Bioreactor Landfill as Characterized by a Short-term Air Pump Test

摘要

A system of vertical wells was evaluated for its potential to inject air into the landfilled waste mass. Air was injected into each of 134 2-inch diameter vertical wells installed at three different depths at a series of flow rates ranging from 5 to 50 scfm. The corresponding steady state pressure that developed in the well was recorded. The surrounding waste permeability was estimated using the flow and pressure data. The results of the short-term air pump tests indicated that air permeability decreased with depth and that the mean air permeabilities of waste in the three different layers (10-20 ft, 20-40 ft and 40-60 ft depth) were significantly different from each other at a 0.1% level of significance. Potential reasons for lower permeability in deeper layers include lower porosity of waste in deeper sections due to higher overburden pressure, higher moisture levels compared to upper sections of the landfill and the presence of leachate in deep wells. The results did indicate that higher moisture contents did significantly reduce air permeability of the waste.