v>EPA
U.S. Environmental
Protection Agency
Office of Solid Waste
and Emergency
Response
Technology
Innovation Office
EPA/542/N-92/001 No. 8 March 1992
The applied technologies journal for Superfund removals and remedial actions and RCRA corrective actions
Good News for
Savannah
River
Dept. of Energy's Integrated
Demonstration Program to
Contribute to TECH TRENDS
Vw e're excited to carry in this is-
sue of TECH TRENDS an article on
horizontal wells for in situ air stripping
that comes from the Department of
Energy's (DOE) Integrated Demon-
stration Program at the Savannah
River Site. We hope that it is the first
of many articles from Savannah River.
DOE's Integrated Demonstration
Program was developed to facilitate
timely and effective application of new
and enhanced technologies to meet
DOE's environmental restoration
needs. Entire systems and multiple
technologies are assembled and
evaluated as part of a collaborative
effortwith DOE laboratories, universi-
ties, federal agencies and private in-
dustries. The Savannah River
program involves innovative ground-
water and soil technologies.
New Information Sources
Available
Don't miss this issue's special insert
that highlights EPA's Technology In-
novation Office's new automated da-
tabase, the Vendor Information
System for Innovative Treatment
Technologies (VISITT), and a new
publication entitled Innovative Treat-
ment Technologies: Overview and
Guide to Information Sources.
Horizontal Wells for Cost Effective
In Situ Air Stripping
Volatile organics
In situ air
stripping
Soil and
groundwater
by Caroline Teelon
Westinghouse Savannah River Company
I he Department of Energy (DOE) has developed and
demonstrated an in situ air stripping technique that utilizes
horizontal wells to remove volatile organic solvents from
soil and groundwater. The demonstration was part of the
DOE's Savannah River Integrated Demonstration Program. At the site, an abandoned
process sewer line leaked trichloroethylene and tetrachloroethylene into soil and
groundwater. Air injection and extraction using horizontal wells has several advan-
tages over traditional air stripping. With horizontal wells, contaminant extraction can
follow natural paths of high permeability-most likely the same paths taken by the
contaminant leaking downward from the upper levels of the soil strata. The position-
ing of horizontal wells can be planned to conform to the distribution of subsurface
contamination and can optimize the results of in situ remediation by providing more
contact area with the contaminant plume. Horizontal wells also allow access under
surface structures and buildings. This means that storage tanks and lines often associ-
ated with industrial operations can be accessed without demolishing above-ground
structures or installing a vertical drilling rig within the structure. Although more
costly per linear foot to install than vertical wells, a horizontal well system can save on
operating expenses.
Sources of Documents in ATTIC
Treatability Studies (35)
Misting Actions (50)
SITE Program (100)
State of California (110)
Other Federal Agencies (171)
NATO and Int'l (34)
EPA/General (598)
Removal Actions (174)
-v^.™-:
Non-EPA/General (364)
Alternative Treatment Technology Information Center
Printed on Recycled Paper
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SITE Subjects
Slurry Biodegradation
Removes Wide Range of
Organics in Soils
i
by Ronald Lewis
Risk Reduction Engineering Laboratory
Organics
Biodegradation
Soils and
sludges
^J lurry biodegradation in a bioreactor has the po-
tential to treat a wide range of organic contami-
nants such as pesticides, fuels, creosote, pentachlorophenol and
polychlorinated biphenyls. The process has been used to treat coal tars, refin-
ery wastes, hydrocarbons and wood-preserving wastes. Slurry biodegrada-
tion to treat soils and sludges with organic contaminants was pilot-tested on
creosote-contaminated soil from the Burlington Northern Superfund Site in
Brainerd, Minnesota as part of the EPA Superfund Innovative Technology
Evaluation (SITE) Program. This SITE demonstration was conducted at
EPA's Test and Evaluation facility in Cincinnati, Ohio, using a 60-liter
Biolift reactor. Slurry biodegradation can be effective in treating highly-
contaminated soils and sludges that have contaminant concentrations ranging
from 2,500-250,000 mg/kg.
For the SITE demonstration, the contaminated soil was first screened to
remove oversized material. Next, the soil was mixed with water to form a
slurry composed of 20-30% soil by weight. The slurry was passed through a
milling process to achieve a suitable grain size distribution for the bioreactor.
The slurry was fed to a continuously-stirred tank bioreactor, and microorgan-
isms and nutrients were added to enhance the biodegradation process. The
additions included an inoculum of indigenous PAH degraders, an inorganic
nitrogen supplement in the form of NH-N and a media broth containing po-
tassium, phosphate, magnesium, calcium and iron. Once the biodegradation
was completed, the treated slurry was sent to a separation/dewatering system.
The process converted the PAHs into relatively harmless by-products of mi-
crobial metabolism and inorganic salts.
The greatest decline in contaminant concentrations occurred in the first
two weeks of the study. Soil-bound PAH which had initial concentration lev-
els of 728-4,920 mg/kg soil showed a 70-97% reduction (average of 89%)
over nine weeks of testing. Liquid-phase PAHs with original concentration
levels of 1.1 mg/liter were below the detection limits in post-treatment
samples.
The residence time in a bioreactor will vary with the soil or sludge ma-
trix, the physical/chemical nature of the contaminant (including concentration
and the biodegradability of the contaminants). After the biodegradation pro-
cess is completed, the solids can be further treated if they still contain organic
contaminants. The process water can be treated in an onsite treatment system
before it is discharged or recycled back into the slurry system. Should air
emissions occur (depending on waste characteristics), it may be necessary to
use an air pollution control, such as activated carbon.
A Technology Evaluation Report and an Applications Analysis Report
describing the complete demonstration will be available this summer. For
more information, call Ron Lewis at EPA's Risk Reduction Engineering
Laboratory at FTS-684-7856 or 513-569-7856.
Horizontal Wells
(from page 1)
At Savannah River, two horizontal wells
were installed along the abandoned sewer
line. To install the horizontal wells, a curved
bore hole was drilled to a predetermined
depth, then a horizontal bore was drilled for
the length of the well. Sections of the hori-
zontal run of the well contain screen open-
ings to allow for a broader lateral distribution
of gas injection and extraction. Both wells
operated concurrently. First, one well, in-
stalled below the water table (within the con-
tamination zone) was used to inject air from
injection pumps. The pumps drove the air
across the contamination plume so that the
contaminants volatilized. The second well,
installed above the water table was used as a
vapor extraction well to collect the volatil-
ized contaminants and pump them into an
above-ground treatment device. After the
treatment device separated the contaminants
from the air, the air could be recycled into the
injection well or dispersed into the atmo-
sphere. The volatile organics were success-
fully stripped from the groundwater and
soils. In the most effective wells located in
the center of the site, trichloroethylene levels
were reduced from over 1,800 parts per bil-
lion (ppb) to 10 ppb and tetrachloroethylene
levels from 180 ppb to 2 ppb.
The horizontal well process can also be
applied to other volatile organic contami-
nants such as gasoline hydrocarbons, benzene
and other chemicals having an affinity for a
gaseous versus liquid phase, because of a
relatively higher vapor pressure and/or a
lower solubility. The injection medium can
be air or other gas or a gas and liquid mixture
depending on the type of contaminant to be
removed. Air may be the most economical
method for large plumes. Steam also can be
used to facilitate volatilization. Reactants,
such as bicarbonate, which react with the
groundwater to form purging gases, may also
be used. Treatment options for the extracted
volatilized contaminant are: filtration (such
as carbon activated filters); incineration; or
an off-gas stack or similar treatment method.
For more information, call Caroline
Teelon at Westinghouse Savannah River
Company at 803-725-5540.
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Out of the ATTIC
Information on Metals Removal in ATTIC
tPA's Alternative Treatment Technology Information Center (ATTIC) is a source for locating data and technical information on in-
novative treatment technologies for the cleanup of hazardous wastes.
David Smith of EPA Region 8 recently consulted ATTIC looking for information on technologies for remediating former wood
preserving sites. Using his PC and modem, he dialed into ATTIC, accessed the ATTIC database, and performed a summary search for
the phrases "wood preserving" and "wood treatment" and found 35 abstracts that contained information on relevant contaminated sites.
Eighteen of these references were from Records of Decision and the other 17 were treatability studies, removal actions, Superfund In-
novative Technology Evaluation (SITE) Program demonstrations, and case studies. The abstracts described reports on the applications
of various technologies including bioremediation, ultraviolet oxidation, and chemical fixation/stabilization. David then narrowed his
search criteria and found that four of these reports involved sites in his Region.
One of the abstracts found in his fist search was entitled "Recovery of Chemicals from Water Using Ion Exchange: A Case
Study," As explained in the abstract, this report described extraction of heavy metals from stormwater runoff and groundwater using
(see ATTIC page 4)
Successful Stabilization of Organics
by Edward Bates, Risk Reduction Engineering Laboratory
H Organics and
, I inorganics
as inorganic compounds was recently demonstrated by the Silicate Technology Corporation (STC) of r~
Scottsdale, Arizona. This technology is particularly exciting because immobilization technologies, al- i^l Stabilization
though generally effective in immobilizing metallic and other inorganic contaminants, have not been =z^~
effective previously for wastes containing semi-volatile organic constituents. The STC technology fegj Soj|
showed favorable results when it was recently demonstrated as part of the EPA's Superfund Innovative Ip&afcJ
Technology Evaluation (SITE) program at the Selma Pressure Treating Site in Selma, California. '
Former wood treatment operations at the site had contaminated approximately 18,000 cubic yards of soils with high concentrations
of pentachlorophenol (PCP), arsenic, chromium, copper and oil and grease.
For the process, STC developed two proprietary reagents, SOILSORB HC for the organic constituents and SOILSORB HM
for the inorganic constituents. These silicate reagents adsorb the contaminants prior to encapsulating the waste in a strong, leach-
resistant, cement-like material. Results from treatability studies can be used to adjust the amounts of reagents required for stabili-
zation according to variations in organic and inorganic contaminant concentrations.
At Selma, treatment of contaminated soil began with the separation of the coarse and fine waste materials. The coarse materi-
als were crushed to less than 3/8 inch. The waste was then weighed and predetermined amounts of the silicate reagents were
added. The mixture was conveyed to a pug mill mixer where water was added and the mixture blended. (Sludges may be placed
directly into the pug mill, reagents added and mixing continued). Treated material was then placed into onsite molds for curing
and casting and subsequent placement into a prepared storage area for long-term (multi-year) study.
The STC process successfully solidified contaminated soils containing less than 2% oil and grease with a moisture content of
up to 6%. Extensive sampling and analysis before and after treatment compared physical, chemical and leaching properties. Ini-
tial PCP total waste concentrations as high as 10,000 parts per million (ppm) were reduced 91 to 97% (to as low as 53 ppm) as
measured by EPA Method SW846-8270 (methylene chloride extraction). After adjusting data to eliminate any apparent reduction
due to dilution, standard Toxicity Characteristic Leaching Procedure (TCLP) leach tests on raw and waste material produced small
and inclusive numbers for PCP but indicated up to 92% reduction (from 1.82 ppm to 0.09 ppm) for arsenic and 97% for copper
(from 9.43 ppm to 0.06 ppm). Substituting distilled water for acetic acid in the TCLP procedure indicated reductions up to 97%
for PCP (from 40.0 ppm to 0.6 ppm), 98% for arsenic (from 0.80 ppm to less than 0.01 ppm) and 90% for copper (from 0.56 ppm
to 0.03 ppm). Permeability of the treated waste was low: l/10th of a foot per year (< 1.7 x 10"7 cm/set). Unconfined compressive
strength of the treated wastes was moderately high, averaging 260-350 pounds per square inch. The treated waste volume in-
creased 59-75% over the original waste volume.
Replication of the process should prove cost effective. The estimate for treatment of large amounts of wastes (15,000 cubic
yards) similar to waste found at Selma is approximately $200 per cubic yard.
An Applications Analysis Report should be available by mid-1992. For more information, call Ed Bates at the Risk Reduction
Engineering Laboratory at FTS-684-7774 or 513-569-7774.
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Subsurface Restoration Conference
June 21-24, 1992
This conference will present state-of-the-art assessments of regulatory strategy, basic science,
site characterization, contaminant immobilization and containment, and technologies for con-
taminant removal and destruction. It is sponsored by EPA and four national research centers.
The conference will be held at the Doubletree Hotel-Lincoln Centre, Dallas, Texas. The poster
title deadline is March 16. Extended abstracts must be submitted by May 4. For more informa-
tion call 713-285-5429.
ATTIC (from page 3)
ion exchange treatment. The site, an operating wood treatment plant, was contaminated with chromium, copper and arsenic. The re-
ported concentration of chromium in the groundwater was originally 50 ppm. A reduction in concentration to 11 ppb was achieved.
Mr. Smith searched for other reports on ion exchange and found 26 more abstracts.
Another abstract he found was entitled "Arsenic Removal Using Electrochemically Generated Iron in Conjunction with Hydrogen
Peroxide Addition." This paper compared several physicochemical processes that are commonly used in the removal of metals from
water such as precipitation, coprecipitation, surface complexation, and electrostatic attraction. The feasibility of electrochemical tech-
nology for arsenic and chromium removal was studied using bench-scale tests and treatability studies.
From these and other abstracts, Mr. Smith was provided with information that included publication references, contact names, ad-
dresses and phone numbers. After scanning the abstracts he had retrieved, Mr. Smith called the ATTIC System Operator and re-
quested the full reports described in the abstracts. Brian, one of the System Operators, copied the reports and sent them out the same
day.
Over 1400 members of the hazardous waste community are registered users of the ATTIC system. There is no charge for
accessing, searching or downloading reports from the system. Information on ATTIC is available from the System Operator at
301-670-6294 or Joyce Perdek, of EPA's Risk Reduction Engineering Laboratory, at FTS-340-4380 or 908-321-4380. To access
ATTIC by modem, dial 301-670-3808.
To order additional copies of this or previous issues of Tech Trends, call the publications unit at CERI.
(513) 569-7562 or FTS 684-7662 and refer to the document number on the cover of the Issue.
To be Included on the permanent mailing list for Tech Trends, call 703-308-8800.
Tech Trends welcomes readers' comments, suggestions for future articles and contributions.
Address correspondence to: Managing Editor, Tech Trends (OS-110W),
U.S. Environmental Protection Agency, 401 M Street, SW., Washington, DC 20460.
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Environmental
Agency
Protection
Center for Environmental Research
Information
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