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Title: Water Balance Measurements and Computer Simulations of Landfill Covers.

Abstract

Abstract not provided.

Authors:
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1143346
Report Number(s):
SAND2005-2971
526335
DOE Contract Number:
DE-AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Dwyer, Stephen F. Water Balance Measurements and Computer Simulations of Landfill Covers.. United States: N. p., 2005. Web. doi:10.2172/1143346.
Dwyer, Stephen F. Water Balance Measurements and Computer Simulations of Landfill Covers.. United States. doi:10.2172/1143346.
Dwyer, Stephen F. Sun . "Water Balance Measurements and Computer Simulations of Landfill Covers.". United States. doi:10.2172/1143346. https://www.osti.gov/servlets/purl/1143346.
@article{osti_1143346,
title = {Water Balance Measurements and Computer Simulations of Landfill Covers.},
author = {Dwyer, Stephen F.},
abstractNote = {Abstract not provided.},
doi = {10.2172/1143346},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun May 01 00:00:00 EDT 2005},
month = {Sun May 01 00:00:00 EDT 2005}
}

Technical Report:

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  • The goal of disposing of low-level radioactive and hazardous waste in shallow landfills is to reduce risk to human health and the environment by isolating contaminants until they no longer pose an unacceptable hazard. In order to achieve this, the Department of Energy Environmental Restoration Program is comparing the performance of several different surface covers at Material Disposal Area (MDA) B in Los Alamos. Two conventional landfill were compared with an improved cover designed to minimize plant and animal intrusion and to minimize water infiltration into the underlying wastes. The conventional covers varied in depth and both conventional and improvedmore » designs had different combinations of vegetation (grass verses shrub) and gravel mulch (no mulch verses mulch). These treatments were applied to each of 12 plots and water balance parameters were measured from March1987 through June 1995. Adding a gravel mulch significantly influenced the plant covered field plots receiving no gravel mulch averaged 21.2% shrub cover, while plots with gravel had a 20% larger percent cover of shrubs. However, the influence of gravel mulch on the grass cover was even larger than the influence on shrub cover, average grass cover on the plots with no gravel was 16.3%, compared with a 42% increase in grass cover due to gravel mulch. These cover relationships are important to reduce runoff on the landfill cover, as shown by a regression model that predicts that as ground cover is increased from 30 to 90%,annual runoff is reduced from 8.8 to 0.98 cm-a nine-fold increase. We also found that decreasing the slope of the landfill cover from 6 to 2% reduced runoff from the landfill cover by 2.7-fold. To minimize the risk of hazardous waste from landfills to humans, runoff and seepage need to be minimized and evapotranspiration maximized on the landfill cover. This has to be accomplished for dry and wet years at MDA B. Seepage consisted of 1.9% and 6.2% of the precipitation in the average and once in ten year events, respectively, whereas corresponding values for runoff were 13% and 16%; these changes were accompanied by corresponding decreases in evapotranspiration, which accounted for 86% and only 78% of the precipitation occurring on the average and once in ten year even~ respectively.« less
  • The water balance relationships of the Area P landfill in Los Alamos were studied in a preliminary attempt to hydrologically characterize and successfully close this shallow land burial site. The current Resource Conservation and Recovery Act status of the site is discussed and plans to reach site closure are presented along with the waste use history and description of the site. The precipitation and temperature at the Area P landfill are evaluated and soil volumetric water content data collected at the site are presented along with calculations of water inventories in the backfill and underlying tuff. The results of hydrologicmore » modeling studies are then presented for various scenarios at the landfill, for both those with and without a final closure cover. A final set of design recommendations is presented relative to improving the final approved closure plan for this landfill. 25 refs., 20 figs., 2 tabs.« less
  • Two- and three-dimensional finite-difference computer programs simulating methane recovery systems in landfills have been developed. These computer programs model multicomponent combined pressure and diffusional flow in porous media. Each program and the processes it models are described in this report. Examples of the capabilities of each program are also presented. The two-dimensional program was used to simulate methane recovery systems in a cylindrically shaped landfill. The effects of various pump locations, geometries, and extraction rates were determined. The three-dimensional program was used to model the Puente Hills landfill, a field test site in southern California. The biochemical and microbiological detailsmore » of methane generation in landfills are also given. Effects of environmental factors, such as moisture, oxygen, temperature, and nutrients on methane generation are discussed and an analytical representation of the gas generation rate is developed.« less
  • This report documents the results of a simulation of the performance of a two-layer infiltration barrier for a nonradioactive dangerous waste landfill (NRDWL) at the US Department of Energy's Hanford Site in semi-arid southeast Washington State. The performance of the barrier was simulated for a period of 10 years using the UNSAT-H version 2.0 groundwater flow computer code. Pacific Northwest Laboratory performed this simulation to compare results using UNSAT-H 2.0 with those of the US Environmental Protection Agency's Hydrologic Evaluation of Landfill Performance (HELP) version 2.0 code. A conceptualization of the actual landfill barrier design was modeled using both codes.more » This model was simulated using 10 years of daily meteorological data collected at the Hanford Meteorological Station from 1979 through 1988. The intent of the comparison was to demonstrate that HELP conservatively predicts deep percolation of meteoric water at the Hanford Site. This demonstration required that the two codes be used to simulate the same conceptual model using identical, or at least essentially equivalent, input data. Comparing the results of the 10-year simulations showed that for the meteorological data and soil properties modeled the HELP 2.0 code was more conservative than the UNSAT-H code. HELP predicted a net drainage or deep percolation of 0.3592 cm (0.1556 in.) from the barrier for the 10-year period simulated. None to the UNSAT-H simulations predicted any deep percolation. HELP also predicted a greater proportion of precipitation returned to the atmosphere through evapotranspiration than did the UNSAT-H simulations in spite of the larger precipitation values being provided to HELP through an apparent data entry error. 14 refs., 11 figs., 8 tabs.« less
  • The water balance and long-term performance of different covers have been monitored on the Georgswerder landfill (Hamburg, Germany) since 1988. Evapotranspiration and drainage above the liners are the major components of the water balance. The liners tested performed very differently. The compacted soil liners have lost their efficiency due to desiccation and shrinkage. The flexible membrane liners (used in combination with compacted soil liners) and an extended capillary barrier performed very well. A slight periodical desiccation due to thermally induced water transport was observed within the soil liners below the flexible membranes. Finally, the authors discuss the suitability of compactedmore » soil liners in landfill covers and the use of other, proposed systems with an intrinsic ability for control.« less