Estimating the hydraulic conductivity of landfilled municipal solid waste using the borehole permeameter test

This paper reports the in situ field saturated hydraulic conductivity of municipal solid waste at a landfill in Florida. The saturated hydraulic conductivity (K,) was estimated at 23 locations using the borehole permeameter test, a method commonly used for determination of the K-s of unsaturated soil. The K-s of the landfilled waste was found to range from 5.4 X 10(-6) to 6.1 X 10(-5) cm/s. The K-s was found to be on the lower end of the range of K, reported by previous studies. The hydraulic conductivity of the waste decreased with depth, the likely result of greater overburden pressures associated with deep locations of the landfill. Permeability values (k(w)) of the landfilled waste calculated based on K-s were compared with permeability values estimated using air as the fluid (air permeability, k(a)). Values of k(a) were found to be approximately three orders of magnitude greater than those of k(w). The lower permeability of the waste to water was primarily attributed to entrapped gas. Other factors such as potential clogging of media and short-circuiting of air along the well may also have contributed to the differences in k(a) and k(w).