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| Resource Library > Technology Transfer > Programs and Initiatives > Landfill Covers > Cost Performance |
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Costs
Costs for landfill covers include both construction and long-term maintenance costs. However the estimates shown below are for construction costs only.
Conventional Landfill Cover Cost
Cost data contained in the "Survey of Air Force Landfills, Their Characteristics, and Remediation Strategies" reveal that costs to the Air Force for conventional landfill covers vary from $319,000 and $571,000 per acre.
Costs to the Air Force for Completed, Conventional Landfill Covers
| Base |
Landfill Number |
Area (Acres) |
Cost |
Cost per Acre |
Cover Type |
| Chanute |
LF-1 |
19 |
$8,363,407 |
$440,179 |
RCRA Cover, estimated |
| LF-2 |
20 |
$9,014,113 |
$450,706 |
RCRA Cover, estimated |
| LF-3 |
17 |
$7,661,996 |
$450,706 |
RCRA Cover, estimated |
| LF-4 |
15 |
$6,760,584 |
$450,706 |
RCRA Cover, estimated |
| Keesler |
LF-3 |
10 |
$5,000,000 |
$500,000 |
Clay barrier |
| Lackland |
LF028 |
20 |
$8,000,000 |
$400,000 |
Clay and Membrane Barrier |
| LF029 |
7 |
$4,000,000 |
$571,429 |
Clay and Membrane Barrier |
| Pease |
LF 5 |
30 |
$9,559,071 |
$318,636 |
Clay and Membrane Barrier |
ET Landfill Cover Cost
The Air Force obtained fully developed construction cost estimates for both a conventional and an ET cover for Landfill 6 at F. E. Warren AFB. Both cost estimates were based on complete cover designs for the site. Estimates for the conventional cover, included both compacted clay and geomembrane barriers.
The cost estimates for both of the conventional covers on Landfill 6 were consistent with or lower than the costs reported in the AFCEE landfill survey, "Survey of Air Force Landfills,Their Characteristics, and Remediation Strategies". The estimates suggest that the cost savings from implementing the ET cover on this site would be in the range of $200,000 to $250,000 per acre.
Cost Comparison of Landfill Covers for Landfill 6 at F. E. Warren AFB
|
Cover Type
|
Cost ($/Acre)
|
Savings with ET Cover ($/Acre)
|
| ET cover |
$147,600 |
---------- |
| Geosynthetic barrier |
$359,500 |
$211,900 |
| Compacted clay and membrane barrier |
$395,000 |
$247,400 |
Other, more conservative and generic estimates indicate construction cost savings from using the ET cover at $150,000 per acre. Additional detail regarding costs is available in "Survey of Air Force Landfills, Their Characteristics, and Remediation Strategies". The paper by Hauser et al. (2001) contains additional detail regarding costs for ET landfill covers.
Long-term Costs
During the long life of a landfill cover, maintenance is required on a regular basis. In addition, waste subsidence and other natural occurrences may damage the cover. Conventional covers are relatively expensive to repair because of the inaccessibility and complexity of the barrier and drainage layers. ET covers, however, are of simpler construction and thus much less costly to repair.
Performance of Conventional Barrier-type Covers
Conventional barrier-type landfill covers often leak, even though the objective is an "impermeable" barrier to the natural movement of water downward in response to the force of gravity. Melchior (1997) reported from a German experiment that after five years a clay barrier cover was leaking 150 to 200 mm/year (about half of the annual precipitation). He also stated that geosynthetic clay barriers leaked 45 to 63 mm of water in only four months of use. Roessler et al. (2002) reported that conventional covers employed at three sites with greater than 450 mm/year precipitation leaked between 2 and 22 percent of annual precipitation through the cover.
Performance of ET Landfill Covers
ET landfill covers use no barrier layers, but rely instead on storage of water within the root zone of native grasses until the ET process can empty the soil water reservoir. Hauser et al. (2001) reviewed extensive and long-term field measurements which demonstrated that the ET cover concept is sound and can control water movement. The long term tests measured the water balance at sites typical of all or parts of 10 states. The tests covered time periods of 33 years to centuries. Dwyer (2001) tested six types of landfill covers, including conventional and ET covers. He stated that "The evapotranspiration cover appears to be leading the way in the third year of testing." In addition to lower construction costs, the ET cover offers equal or better performance than conventional barrier-type landfill covers.
References
- Dwyer, S. F. 2001. Finding a Better Cover. Civil Engineering Journal, January: 58-63.
- Hauser, V. L., B. L. Weand, and M. D. Gill. 2001. Natural Covers for Landfills and buried Waste. Am. Society of Civil Engineers, J. Environmental Engineering, vol. 127, no. 9: 768-775
- Melchior, S. 1997. In Situ Studies on the Performance of Landfill Caps. Proceedings International Containment Technology Conference, St. Petersburg, FL. 365-373
- Roesler, A. C., C. H. Benson, and W. H. Albright. 2002. Field Hydrology and Model Predictions for Final Covers in the Alternative Assessment Program - 2002. Geo Engineering Report No. 02-08, Univ. of Wisconsin, Madison, WI. Available from the DRI/EPA ACAP web site.
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