Introduction to Phytoremediation - CLU-IN

3.8.10 System Costs
In general, vegetative covers are considered cost-effective
remedies. Cost estimates indicate notable savings for
an evapotranspiration cover compared to a traditional cover
design (RTDF 1998).
3.8.11 Selected References
Dobson, M. C., and A. J. Moffat, 1993. The Potential for
Woodland Establishment on Landfill Sites. HMSO Press.
The information presented in this report focuses primarily
on the effects of the landfill environment on tree
growth, the typical rooting pattern of trees, the likelihood
of windthrow, and the possible effects of trees on landfill
hydrology.
Flower, F. B., E. F. Gilman, and I.A. Leone. 1981. Landfill
Gas, What It Does to Trees and How Its Injurious Effects
may be Prevented. J. of Arboriculture. 7(2):February
1981.
Methods are suggested for preventing the entry of landfill
gases into the root zones of the trees and in accommodating
other tree growth problems found to be associated
with former refuse dumping areas. These methods
include gas venting and blocking, irrigation, planting
adaptable species, using small sized specimens in
preference to large, and providing adequate maintenance.
Environmental Science and Research Foundation Conference
Proceedings. 1997. Landfill Capping in the Semi-
Arid West: Problems, Perspectives, and Solutions. May
21-27, 1997. Grand Teton National Park.
These conference proceedings address the following:
• Regulatory performance and monitoring requirements
for landfills and caps
• Perspectives and problems with landfill closure
• What landfill covers do and how they do it
• Different approaches to landfill caps
• Perspective and alternative cap designs
• Economic issues
RTDF. 1998. Summary of the Remediation Technologies
Development Forum Alternative Covers Assessment Program
Workshop. February 17-18, 1998, Las Vegas, NV.
http://www.rtdf.org.
The meeting minutes of these workshops on alternative
covers include a discussion of the technical and regulatory
issues relating to the use of vegetative covers. Regulatory
and industry participants present their views on
the use of alternative covers for a variety of geographic
regions and on the research needs required to validate
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this technology. Models used to assess landfill covers
are included in the discussion.
EPA. 1991. Design and Construction of RCRA/CERCLA
Final Covers. (Seminar Publication, EPA 625-4-91-025).
This seminar publication provides regulatory and design
personnel with an overview of design, construction, and
evaluation requirements for cover systems for RCRA/
CERCLA waste management facilities.
EPA. 1994. Design, Operation, and Closure of Municipal
Solid Waste Landfills. (Seminar Publication, EPA 625-
R-94-008).
This seminar publication provides a documented summary
of technical information presented at a series of
2-day seminars. The goal of the seminars were to
present state-of-the-art information on the proper design,
construction, operation, and closure of Municipal
Solid Waste Landfills.
EPA. Draft December 1998. Technical Guidance For
RCRA/CERCLA Final Covers.
The purpose of this guidance document is to provide
information to facility owners/operators, engineers, and
regulators regarding the regulatory standards, performance
monitoring, and maintenance of final cover systems
for municipal solid waste and hazardous waste
landfills regulated under RCRA, and sites being
remediated under CERCLA. When released (approximately
December 1999), it will be an update to the 1991
EPA document entitled, Design and Construction of
RCRA/CERCLA Final Covers (EPA-625-4-91-025).
3.9 Riparian Corridors/Buffer Strips
3.9.1 Definition/Mechanism
Riparian corridors/buffer strips are generally applied along
streams and river banks to control and remediate surface
runoff and groundwater contamination moving into the river.
These systems can also be installed to prevent downgradient
migration of a contaminated groundwater plume and to degrade
contaminants in the plume. Mechanisms for
remediation include water uptake, contaminant uptake, and
plant metabolism. Riparian corridors are similar in conception
to physical and chemical permeable barriers such as
trenches filled with iron filings, in that they treat groundwater
without extraction containment. Riparian corridors and buffer
strips may incorporate certain aspects of hydraulic control,
phytodegradation, rhizodegradation, phytovolatilization, and
perhaps phytoextraction.
3.9.2 Media
Riparian corridors/buffer strips are used in the treatment
of surface water and groundwater.
3.9.3 Advantages
Secondary advantages include the stabilization of stream
banks and prevention of soil erosion. Aquatic and terres-