Volume 17, Issue 2 (June 1994)
Monitoring System for Hydrologic Evaluation of Landfill Covers
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 climatologic variables, overland flow, percolation, soil temperature, and soil water content. This paper focuses on the construction and instrumentation of the test sections.
A data acquisition and control computer (DACC) is used to collect data and control various components of the monitoring system. The system in Atlanta is powered by 115 volts alternating current (VAC), 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.
The writers have found that a DACC used to remotely monitor the hydrology of final covers must permit system control and remote access. Selection of robust instruments that require minimal calibration and maintenance is also essential. Experience has shown that selecting the sampling frequency is best accomplished through initially sampling rapidly and then adjusting the sampling frequency to obtain representative data. Periodic manual measurements have also been useful in error checking and in ensuring confidence in the data.