Benson, C. H., P. J. Bosscher, D. T. Lang, and R. J. Pliska. 1994.
Monitoring System for Hydrolgic Evaluation of Landfill Covers.
Geotechnical Testing Journal, GTJODJ, Vol. 17, No. 2, June, pp. 138-149.
(posted June 8, 1996)
Three test sections were constructed and instrumented to assess the hydrologic behavior of earthen final covers at two municipal solid waste landfills. A traditional design using a "resistive barrier" was used for two of the test sections, whereas an alternative design using a "capillary barrier" was used for the third test section. The test sections were built in two distinctly different climates: humid with high precipitation (Atlanta, Georgia) and arid (East Wenatchee, Washington). Each test section
was instrumented to measure climatological variables, overland flow, percolation, soil temperature, and soil water content. This paper focuses on the construction and instrumentation of the test sections.
Soil water content was monitored using time domain reflectometry (TDR) techniques. Three nests of 300-mm-long stainless steel twin-rod probes were placed along the centerline of each test section; they are located at 5, 10, and 15 m upslope from the bottom berm. In Atlanta, four probes were placed in each nest (depths=0.15, 0.38, 0.61, and 0.84 m) whereas five probes were placed in each nest at Wenatchee (depths = 0.08, 0.23, 0.38, 0.53, and 0.68 m). Four measurements of water content can be conducted every minute; a full set of measurements are typically made once per hour.
A data acquisition and control computer is used to collect data and control various components of the monitoring system. The system in Atlanta is powered by 115 volts alternating current whereas the system in Wenatchee is powered by solar panels and batteries. Telecommunications are established via traditional telephone lines or by cellular transmission. Commercially available equipment sold by a variety of vendors was used. After approximately two years of operation, maintenance requirements for the systems have been minimal.