APPENDIX D

 

 

MEMO

 

Date: September 9, 1999

 

To: RTDF Working Group for Phytoremediation at Petroleum Contaminated Sites

 

From: Jim Brown, Lockheed Martin/REAC & Royal Nadeau, U.S. EPA's Environmental Response Team Center (ERTC), Edison, NJ

 

Re: Suggestions for a Phased Approach to Bioremediation at Petroleum Contaminated Sites

 

A phased approach to bioremediation utilizing both conventional land treatment bioremediation followed by plant-mediated bioremediation may be more cost effective than conventional land treatment alone. The following information provides a basis for this approach:

 

Assumptions:

 

 

 

Phased vs Non-Phased Approach to Bioremediation

 

Timing of Phase II Initiation

A technical basis for deciding when to initiate Phase II treatment is desirable. A 'rule of thumb' might after one season of Phase I treatment. More definitive criteria could be the following:

 

* An assumption is made that for soil depths of 6 inches or less, steady state oxygen flux into soil may be adequate without the mixing (soil repositioning) that results from tillage. However, regular mixing may still be advantageous by preventing surface-limited reactions from controlling the biodegradation rate ('mixing effect').

 

 

 

** Levels of >2 to 3% TPH cause oily films to be present on soil particle surfaces, adversely affecting soil physical and chemical properties, and plant growth, even if plant toxins are absent:

 

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