ESTCP Project #1011, Rhizosphere
Final Report
This document was produced by the Interstate Technology Regulatory Cooperation (ITRC)
workgroup. The intent of this document is to provide a tool that can be used to determine if
phytoremediation has the ability to be effective at a given site. It is designed to compliment
existing phytoremediation documents. It allows the user to take basic information from a specific
site and, through a flow chart layout, decide if phytoremediation is feasible at that site. In its
discussion of phytoremediation of organics, rather than specifically petroleum, the ITRC
Phytoremediation Decision Tree document recommends first using the decision tree to assess if
phytoremediation is a viable option, and then conducting treatability studies. These studies are
described as growing a variety of plants proposed for use in a range of concentrations, to assess
the fate of the contaminant, especially for transpiration losses, and to evaluate if desired results
are achieved. The ITRC document is useful guidance for many organics. For petroleum
specifically, a great deal is known about microbial degradation pathways, the generally accepted
operative mechanism for rhizosphere-enhanced remediation.
Phytoremediation Technical and Regulatory Guidance Document, Interstate Technology and
Regulatory Cooperation Work Group (ITRC), Phytotechnologies Work Team Document No:
PHYTO-2. 124 pp, Apr 2001. http://www.itrcweb.org/PHYTO2.pdf.
This document covers a wide range of phytoremediation applications and is not limited to
rhizosphere remediation of petroleum in surface soils. It provides useful background and
descriptions of different mechanisms involved in phytoremediation of organics and metals. It
discusses regulatory and permitting processes, leaching and contaminant mobilization concerns.
The document provides an extensive list of possible monitoring parameters, all of which are
based on changes in the contaminant chemistry. The document recommends treatability studies,
both for evaluating plant survival and beneficial effects of the plants. Suggestions that are made
for treatability studies include plant selection, contaminant fate and transport studies, mass
balance studies, and microbial screening studies. The point is made that regulators are likely to
require treatability studies prior to use of phytoremediation. The importance of plant selection is
stressed. Again, this document covers a wide range of contaminant and is not limited to, or
focused on, petroleum in surface soils.
Phytoremediation of Petroleum Hydrocarbons in Soil. Remediation Technologies
Development Forum, Phytoremediation Action Team, Field Study Protocol, July 1999.
http://www.rtdf.org/public/phyto/protocol/protocol99.htm.
This is the guidance document developed by the EPA-RTDF Phytoremediation Action Team.
Rather than a treatability protocol, it is guidance for a series of field demonstrations for using
phytoremediation for petroleum-contaminated soil. The three cold-region ESTCP sites were part
of this effort.
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