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inspection analogous to the pre-final inspection shall be
conducted and documented by the Region before preparing the
preliminary closeout report.
Even though the site is declared a "Construction
Completion", the operable unit involving bioremediation or SVE
remains classified as an ongoing remedial action. The operable
unit remedial action will not be complete until cleanup goals
specified in the Record of Decision are achieved and a remedial
action report has been submitted to and approved by EPA.
Headquarters will continue to comment on completion
decisions through review of the preliminary closeout report as
described in previous guidance. The Hazardous Site Control
Division (HSCD) serves as the clearinghouse for Construction
Completions; therefore, all draft preliminary closeout reports
should be sent to the following address for Headquarters review
and comment:
John J. Smith, Chief
Design and Construction Management Branch
Hazardous Site Control Division (5203G)
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
If you have any questions regarding this directive, you may
contact your HSCD RD/RA Regional Coordinator at (703) 603-8830.
Attachment
cc: Superfund Branch Chiefs
Richard Guimond
OERR Division Directors
Bruce Diamond, OWPE
David W. Ziegele, OUST
Sylvia Lowrance, OSW
Walter Kovalick, TIO
James Makris, CEPPO
Tim Fields, SRO
George Wyeth, OGC
The policies set forth in this directive are intended solely
as guidance. They are not intended, nor can they be relied
upon, to create any rights enforceable by any party in
litigation with the United States. EPA officials may decide
to follow the policies provided in this directive, or to act
at variance with the directive, on the basis of an analysis
of specific circumstances, and to change them at any time
without public notice.
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Attachment
OSWER Directive 9320.2-06
EPA540-F-93-019
PB93-963327
TECHNOLOGY DESCRIPTIONS
In-situ Soil Vapor Extraction
In-situ SVE units are designed to physically remove volatile
compounds from soil layers located above the water table. The
process employs vapor extraction wells alone or in combination
with air injection wells. Vacuum blowers induce air through the
soil layers, which strip volatile compounds from the soil and
carries them to the surface via extraction wells. Volatiles are
controlled by adsorption onto activated carbon, incineration, or
condensation by refrigeration. SVE systems vary in size, but
consist of several extraction wells and surface blower/
collection units.
Since SVE is in-situ, construction activity is primarily
limited to the installation of extraction wells, blowers, and
collection unit. Like aquifer restoration, the typical SVE site
requires minimal post-construction activity. An example is the
installation of additional extraction wells.
In-situ Bioremediation
In-situ bioremediation uses additives to degrade organic
contaminants in soils and aquifers. Additives are injected into
the soil or aquifer under pressure through wells or spread on the
surface for infiltration to the contaminated material. The type
of additive used at a particular site varies, but generally
consists of either an oxygen source, nutrients, or perhaps micro-
organisms.
In-situ bioremediation is similar to aquifer restoration
remedies, in that it generally requires minimal post-construction
activity once the initial installation of injection wells and
surface equipment is completed.
Ex-situ bioremediation
Ex-situ bioremediation uses microorganisms to degrade
organic contaminants in excavated soil, sludge, and solids.
Several variations of ex-situ bioremediation exist, and the
amount of post-construction activity varies from site to site.
Two common applications of ex-situ bioremediation are: slurry-
phase bioremediation, in which soils are mixed with water to form
a slurry; and solid-phase bioremediation, in which soils are
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placed in a liner, tank or building and tilled with water and
nutrients. Variations of the latter process are called land
farming or composting.
Ex-situ bioremediation can be similar to aquifer restoration
remedies. When physical construction is completed, the
contaminated material is safely stored, and only routine activity
such as tilling remains to be done. Because of the different
approaches to ex-situ bioremediation, decisions on declaring
Construction Completion at these sites should be handled on a
site specific basis.
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