A Water Balance Study of Two Landfill Cover Designs for Semiarid Regions

Abstract

The results from several field experiments on methods to control soil erosion, biointrusion, and water infiltration were used to design and test an enhanced landfill cover that improves the ability of the disposal site to isolate buried wastes. The performance of the improved cover design in managing water and biota at the disposal site was compared for 3 yr with that obtained from a more conventional design that has been widely used in the industry. The conventional cover design consisted of 20 cm of sandy loam topsoil over 108 cm of a sandy silt backfill, whereas the improved design consists of 71 cm of topsoil over a minimum of 46 cm of gravel, 91 cm of river cobble, and 38 cm of sandy silt backfill. Each plot was lined with an impermeable liner to allow for mass balance calculation of water dynamics. Results over a 3-yr period, including 2 wet yr, demonstrated that the improved design reduced percolation of water through the landfill cover by a factor of >4 over the conventional design. This decrease in percolation was attributed to a combination of increased evapotranspiration from the plant cover and the effect of a capillary barrier embedded in the enhanced cover profile in diverting water laterally in the cover. The field data are finally discussed in terms of its usefulness for waste management decisions to be made in the future for both new and existing landfills at Los Alumos, NM, and at other semiarid waste disposal sites.

Wastewater disposal to landfill-sites: A synergistic solution for centralized management of olive mill wastewater and enhanced production of landfill gas

“…Accordingly, the costs were higher by a factor of 25% and reached 0.26 V/m 3 wastewater disposed (see Table 3). Water evaporation can be further enhanced by fostering hydrophilic vegetation onto the soil cover (Nyhan et al, 1990;Albright et al, 2004). In this case a significant cost factor included the purchase and placement of substrate (gravel) and plants.…”

Impact of Landfill Closure Designs on Long-Term Natural Attenuation of Chlorinated Hydrocarbons

“…This conclusion is based on the fact that capillary barriers have been used primarily in experimental installations, and field experience shows that they may fail periodically (Nyhan et al, 1990;Warren et al, 1996a). Based on the research of Warren et al (1996b), even in semi-arid climates, the ability of capillary barriers to shed water laterally along the capillary break within covers is likely to be inadequate, particularly during months with frequent rainfall.…”

Hydrologic Behavior of Two Engineered Barriers Following Extreme Wetting

“…Rather than providing just an impermeable barrier to stop downward water movement, these barriers are designed to rely on several natural, interactive processes to function effectively. Determining the engineered barrier's water balance has been identified as one of the most effective ways to evaluate the barrier's overall performance (Nyhan et al, 1990;Ward and Gee, 1997). The water balance of the engineered barrier test plots quantitatively accounts for all water impacting the test plots.…”