title: Review of state of the art methods for measuring water in landfills.
abstract: In recent years several types of sensors and measurement techniques have been developed for measuring the moisture content, water saturation, or the volumetric water content of landfilled wastes. In this work, we review several of the most promising techniques. The basic principles behind each technique are discussed and field applications of the techniques are presented, including cost estimates. For several sensors, previously unpublished data are given. Neutron probes, electrical resistivity (impedance) sensors, time domain reflectometry (TDR) sensors, and the partitioning gas tracer technique (PGTT) were field tested with results compared to gravimetric measurements or estimates of the volumetric water content or moisture content. Neutron probes were not able to accurately measure the volumetric water content, but could track changes in moisture conditions. Electrical resistivity and TDR sensors tended to provide biased estimates, with instrument-determined moisture contents larger than independent estimates. While the PGTT resulted in relatively accurate measurements, electrical resistivity and TDR sensors provide more rapid results and are better suited for tracking infiltration fronts. Fiber optic sensors and electrical resistivity tomography hold promise for measuring water distributions in situ, particularly during infiltration events, but have not been tested with independent measurements to quantify their accuracy. Additional work is recommended to advance the development of some of these instruments and to acquire an improved understanding of liquid movement in landfills by application of the most promising techniques in the field.
authors.affiliation: Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA. imhoff@udel.edu
authors.forename: Paul T
authors.initials: PT
authors.lastname: Imhoff
authors.forename: Debra R
authors.initials: DR
authors.lastname: Reinhart
authors.forename: Marja
authors.initials: M
authors.lastname: Englund
authors.forename: Roger
authors.initials: R
authors.lastname: Guérin
authors.forename: Nitin
authors.initials: N
authors.lastname: Gawande
authors.forename: Byunghyun
authors.initials: B
authors.lastname: Han
authors.forename: Sreeram
authors.initials: S
authors.lastname: Jonnalagadda
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Townsend
authors.forename: Ramin
authors.initials: R
authors.lastname: Yazdani
mesh_terms: D012037:Refuse Disposal / Q000379:methods*; D014867:Water / Q000737:chemistry*; D014872:Water Movements
chemical_list: D014867:Water