PROCEEDINGS
TECHNICAL ASSISTANCE TO U.S. EPA REGION IX:
FORUM ON REMEDIATION OF WOOD PRESERVING SITES
October 24-25, 1988, San Francisco, California
Coordinated by
PEI Associates, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
Contract No. 68-03-3413
Work Assignment No. 19-1M and 20-1G
PN 3741-19-1M and 3741-20-AG
I
Technical Project Monitors
Edwin F. Barth
and
John E. Matthews
U.S. ENVIRONMENTAL PROTECTION AGENCY
Risk Reduction Engineering Laboratory
26 West Martin Luther IQng Drive
Cincinnati, Ohio 45268
and
Robert S. Kerr Environmental Research Laboratory
P.O. Box 1198
Ada, Oklahoma 74820
. March 1989
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CONTENTS
Page
List of Speakers
List of Attendees
Agenda
Section 1: Introduction
Section 2: Status of CERCLA Wood Preserving Sites
Section 3: Forum Summary
Section 4: Forum Presentations
v
IV
in
2-1
4-1
3-1
1-1
Overview of the Wood Preserving Industry -
Dr. Gary D. McGinnis, Mississippi State University, MS
Field Experience with the KPEG Reagent -
Alfred Komel, EPA-RREL, Cinci., OH
In-Situ Biodegradation of Organic Pollutants in Groundwater -
Dr. C. Herben Ward, Rice University, Houston, TX
Onsite Bioremediation of Wood Preserving Contaminants in Soils -
Dr. Ronald C. Sims, EPA-RSKERL, Ada, OK (Utah State University)
Existing Data on Wood Preserving Waste Incineration -
Donald A. Oberacker, EPA-RREL, Cinci., OH
Pump-and-Treat Technology -
Dr. Joseph F. Keely, Ground-Water Quality Consultant, Portland, OR
In-Situ Soil Washing and Flushing Technologies -
Thomas C. Sale, CH2M Hill, Denver, CO
Physical Separation for Excavated Soils and In-Situ Vacuum Extraction -
Frank J. Freestone, EPA-ORD, Edison, NJ
Groundwater Contaminants at Wood Treatment Facilities -
Jeffrey K. Rosenfeld, EPA-EMSL, Las Vegas, NV (Lockheed Engineering)
Fate and Transport Modeling of Wood Preserving Contaminants in Surface Water -
Dr. Robert B. Ambrose, Jr., EPA-ORD, Athens, GA
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CONTENTS (Continued)
Page
Section 4: Forum Presentations (Continued) 4-1
Capping Wood Preserving Sites -
Dr. Walter E. Grube, EPA-RREL, Cinci., OH
Stabilization/Solidification of Metals in Soils and Sludges -
Edwin F. Barth, EPA-RREL, Cinci., OH
Slurry Walls, Recovery Walls, Interceptor Trenches, and Grout Curtains -
Dr. Walter E. Grube, EPA-RREL, Cinci., OH
Appendix A - Supplementary Material For Overview of the Wood Preserving Industry,
Dr. Gary D. McGinnis, Mississippi State University, MS
Appendix B - Supplementary Material For Field Experience with the KPEG Reagent,
Alfred Kornel, EPA-RREL,Cincinnati., OH
Appendix C - Supplementary Material For In-Situ Biodegradation of Organic Pollutants in
Groundwater, Dr. C. Herbert Ward, Rice University, Houston, TX
Appendix D - Supplementary Material For Onsite Bioremediation of Wood Preserving
Contaminants in Soils, Dr. Ronald C. Sims, EPA-RSKERL, Ada, OK
(Utah State University)
Appendix E - Supplementary Material For Pump-and-Treat Technology, Dr. Joseph F.
Keely, Ground-Water Quality Consultant, Portland, OR
Appendix F - Supplementary Material For In-Situ Soil Washing and Flushing
Technologies Thomas C. Sale, CH2M Hill, Denver, CO
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco, CA
October 24-25,1988
LIST OF
Name
Dr. Robert B. Ambrose, Jr., P.E.
EPA-ORD, Athens, GA
Edwin F. Barth, P.E.
EPA-RREL, Cincinnati, OH
Frank J. Freestone
EPA-ORD, Edison, NJ
Dr. Walter E. Grube, Jr.
EPA-RREL, Cincinnati, OH
Dr. Joseph F. Keely
Ground-Water Quality Consultant
Portland, OR
Alfred Kornel
EPA-RREL, Cincinnati, OH
Dr. Gary D. McGinnis
Mississippi State University, MS
Donald A. Oberacker
EPA-RREL, Cincinnati, OH
Jeffrey K. Rosenfeld
EPA-EMSL, Las Vegas, NV
(Lockheed Engineering)
Thomas C. Sale
CH2M Hill
Denver, CO
Dr. Ronald C. Sims
RSKERL, Ada, OK
(Utah State University)
Dr. C. Herbert Ward
Rice University, Houston, TX
Work/Research Interests
Exposure assessment modeling.
Research & technical assistance in
stabilization of hazardous waste.
Treatment of excavated oils,
sludges, and sediments.
Contaminated soils & cleanup
technologies; soil structures.
Site characterization & review;
technical enforcement support;
technology transfer/training.
Chemical & biochemical methods
to detoxicify halo-organics.
Wood science & technology;
biotechnology; groundwater & soil
analysis.
High temperature incineration of
pesticides and hospital wastes.
Groundwater and soil contamination;
monitoring strategies; hazardous
waste site investigations.
Oil recovery & in-situ soil washing;
hydrogeologic investigations of
hazardous waste sites.
Soil transport & fate; in-situ EPA-
biorcmediation; land treatment
studies.
Microbial/aquatic physiology; water
quality and hazardous materials.
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco, CA
October 24-25, 1988
LIST OF ATTENDEES
Name
Dr. Robert B. Ambrose Jr., P.E.
Edwin F. Barth, P.E
James Basilico
Joanne Benante
Bert Bledsoe
James Brown
Jeffrey Dhont
David Evans
Bernard R. Feather
Felix Flechas
Frank J. Freestone
Rene Fuentes
John R. Gealy
Dr. Walter E. Grube, Jr.
Address
EPA-ORD, College Station Rd.
Athens, GA 30613
EPA-RREL, 26 West Martin
Luther King Dr., Cincinnati,
OH 45268
EPA-ORD, 401 M St., S.W.,
Washington, D.C., 20460
EPA-Region IV, 345 Courtland
St., N.E., Atlanta, GA 30365
EPA-RSKERL, P.O. Box 1198,
Ada, OK 74820
EPA-HQ, 401 M St., S.W.,
Washington, D.C., 20460
EPA-Region IX, 215 Fremont St.,
San Francisco, CA 94105
Phone No.
(404) 546-3130
FTS 250-3130
(513) 569-7669
FTS 684-7669
(202) 382-2583
(404) 347-3433
FTS 257-3433
(405) 332-8800
FTS 743-2011
(202) 475-7240
(415) 974-0990
FTS 454-0990
California Regional Water Quality (707) 576-2220
Control Board, 1440 Guerneville Rd.,
Santa Rosa, CA 95401
California Dept. of Health Services, (415) 540-2596
2151 Berkeley Way, Annex 7,
Berkeley, CA 94704
EPA-Region Vm, 999 18th St., (303) 293-1669
Suite 500, Denver, CO 80202-2405 FTS 564-1669
EPA-ORD, MS-104, Woodbridge (201) 321-6632
Ave., Edison, NJ 08837-3679 FTS 340-6632
EPA-Region X, 1200 Sixth Ave., (206) 442-1599
Seattle, WA 98101 FTS 454-1599
EPA-RSKERL, (Dynamac Coip.), (405) 332-8800
P.O. Box 1198, Ada, OK 74820 FTS 743-2011
EPA-RREL, 26 West MartinLuther (513) 569-7798
King Dr., Cincinnati, OH 45268 FTS 684-7798
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX,.San Francisco, CA
October 24-25, 1988
Name
James Hansen
R. Bernie Hayes
Scott G. Huling
Dr. Joseph F. Keely
John Kemmerer
Alfred Kornel
Fran Kremer
Mark Lahtinen
John Lank
Leo Le Vinson
Carole A. Lojek
John Matthews
Dr. Gary D. McGinnis
LIST OF ATTENDEES (Continued)
Affiliation
EPA-Region IX, 215 Fremont St.,
San Francisco, CA 94105
Phone No.
(415) 974-7232
FTS 454-7232
EPA-Region IV, 345 Courtland St., (404) 347-3866
N.E., Atlanta, GA 30365
EPA-RSKERL, P.O. Box 1198,
Ada, OK 74820
Suite 2002, Tanasbourne Mall,
2700 NW 185th Avenue,
Portland, OR 97229
EPA-Region IX, 215 Fremont St.,
San Francisco, CA 94105
FTS 257-3866
(405) 332-8800
FTS 743-2313
(503)645-7556
(415) 974-7112
FTS 454-7112
EPA-RREL, 26 West Martin Luther (513) 569-7421
King Dr., Cincinnati, OH 45268 FTS 684-7421
EPA-RREL, 26 West Martin Luther (513) 569-7346
King Dr., Cincinnati, OH 45268 FTS 684-7346
Minnesota Pollution Control Agency (612) 296-7775
Groundwater & Solid Waste Division
520 Lafayette Rd.,
St. Paul, MN 55155
EPA-Region IV, 345 Courtland St, (404) 347-7603
N.E., Atlanta, GA 30365 FTS 257-7603
EPA-Region IX, 215 Fremont St., (415) 974-7101
San Francisco, CA 94105 FTS 454-7101
PEI Associates, Inc., 11499 (513)782-4767
Chester Rd., Cincinnati, OH 45246
EPA-RSKERL, P.O. Box 1198,
Ada, OK 74820
(405) 743-2233
P.O. Drawer FP, Mississippi Forest (601) 325-3101
Products Lab, Mississippi State
University, MS 39762
Donald A. Oberacker EPA-RREL, 26 West Martin Luther (513)569-7510
King Dr., Cincinnati, OH 45268 FTS 684-77510
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco, CA
October 24-25,1988
LIST OF ATTENDEES (Continued)
Name
Andrew Palestini
Ted Park
Thomas Pheiffer
Eydie Pines
Mark Piros
Jeffrey K. Rosenfeld
Thomas C. Sale
Marion R. Scalf
Dr. Ronald C. Sims
Ken Wallace
Dr. C. Herbert Ward
Ronald G. Wilhelm
Affiliation
EPA-Region III, 841 Chestnut St.,
Philadelphia, PA 19107
California Dept. of Health Services,
5850 Shellmound St., Emeryville,
CA 94608
EPA HQ-OSWER, 401 M St.,
S.W., Washington, D.C., 20460
EPA HQ, 401 M St., S.W.,
Washington, D.C., 20460
Phone No.
(215) 597-1286
FTS 597-1286
(415) 540-2526
(202) 382-4477
FTS 382-4477
(202) 475-9759
FTS 475-9759
California Dept. of Health Services, (415) 540-2529
2151 Berkeley Way, Annex 7,
Berkeley, CA 94704
EPA-EMSL
(Lockheed Engineering),
1050 E. Flamingo Rd., Suite 120,
Las Vegas, NV 89119
CH2M Hill, 6060 S. Willow Dr.,
Denver, CO 80111
EPA-RSKERL, P.O. Box 1198,
Ada, OK 74820
EPA-RSKERL,
(Utah State University)
P.O. Box 1198, Ada, OK 74820
USEPA
Federal Building
Drawer 10096, 301 South Park
Helena, MT 59626-0096
Dept. of Environmental Science &
Engineering, Rice University,
Houston, TX 77251
EPA HQ-OSWER, 401 M St.,
S.W., Washington, D.C., 20460
(702) 734-3211
(303) 771-0900
(405) 332-8800
FTS 743-2011
(405) 332-8800
FTS 743-2011
(406) 449-5414
(713) 527-4086
(202) 382-7944
FTS 382-7944
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco, CA
October 24-25, 1988
DAY 1
7:30
8:00
I.
8:15
n.
9:15
10:15
10:30
11:30
12:45
1:45
2:45
3:00
4:00
5:00
AGENDA
Topic
Registration
Opening Comments
INTRODUCTION
Overview of the Wood Preserving
Industry
TREATMENT TECHNOLOGIES
A. CHEMICAL TECHNOLOGIES
Field Experience with the KPEG
Reagent
Break
B. BIOLOGICAL TECHNOLOGIES
In-Situ Biodegradation of
Organic Pollutants in Ground-
Water
Lunch Break
Onsite Bioremediation of Wood
Preserving Contaminants in Soils
C. PHYSICAL TECHNOLOGIES
Existing Data on Wood Preserving
Waste Incineration
Break
Pump-and-Treat Technology
Speaker
Ronald G. Wilhelm
EPA HQ-OSWER, Washington, D.C.
John Kemmerer
EPA-IX, San Francisco, CA
Dr. Gary D. McGinnis
Mississippi State University, MS
Alfred Komel
EPA-RREL, Cincinnati, OH
Dr. C. Herbert Ward
Rice University, Houston, TX
Dr. Ronald C. Sims
EPA-RSKERL, Ada, OK
(Utah State University)
Donald A. Oberacker,
EPA-RREL, Cincinnati, OH
Dr. Joseph F. Keely
Groundwater Quality Consultant
Portland, OR
In-Situ Soil Washing and
Flushing Technologies
End Day 1
Thomas C. Sale
CH2M Hill, Denver, CO
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FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco, CA
October 24-25,1988
AGENDA (Continued)
Topic Speaker
Opening Comments Ronald G. Wilhelm
EPA HQ-OSWER, Washington, D.C.
C. PHYSICAL TECHNOLOGIES (Cont'd)
Physical Separation for Excavated Frank J. Freestone
Soils and In-Situ Vacuum Extraction EPA-ORD, Edison, NJ
MONITORING STRATEGIES
Groundwater Contaminants
at Wood Treatment Facilities
Break
Jeffrey K. Rosenfeld
EPA-EMSL, Las Vegas, NV
(Lockheed Engineering)
FATE/TRANSPORT
Fate and Transport Modeling of
Wood Preserving Contaminants
in Surface Water
Lunch Break
Dr. Robert B. Ambrose, Jr., P.E.
EPA-ORD, Athens, GA
CONTAINMENT TECHNOLOGIES
Capping Wood Preserving Sites
Stabilization/Solidification of
Metals in Soils and Sludges
Break
Slurry Walls, Recovery Walls,
Interceptor Trenches, and Grout
Curtains
CONCLUSION
Roundtable Discussion:
Summary Comments
Dr. Walter E. Grube
EPA-RREL, Cincinnati, OH
Edwin F. Barth, EPA-RREL
Cincinnati, OH
Dr. Walter E. Grube
EPA-RREL, Cincinnati, OH
General Participation
John Matthews
EPA-RSKERL, Ada, OK
Ronald Wilhelm
EPA HQ-OSWER, Washington, D. C.
End Day 2
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SECTION 1
INTRODUCTION
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SECTION 1
INTRODUCTION
Wood preserving operations have contributed to contamination at a number of sites
proposed or listed on the Superfund National Priorities List (NPL). The U.S.
Environmental Protection Agency (EPA) Region IX office in San Francisco, California
requested technical assistance in evaluating remedial alternatives for Superfund sites
contaminated by wood preservatives (e.g., creosote). Specifically, Region IX requested
that the Robert S. Kerr Environmental Research Laboratory (RSKERL) and the Risk
Reduction Engineering Laboratory (RREL) present a technical program evaluating
remediation technologies for soils and groundwater containing wood preserving
contaminants.
PEI Associates, Inc., in support of RSKERL and RREL coordinated development
and presentation of a two-day forum on the status of CERCLA wood preserving sites and
on remedial technologies potentially applicable to contaminated soil and groundwater at
those sites. A total of forty representatives from thirteen EPA offices, four state regulatory
agencies, and five consulting or academic affiliations attended the forum conducted October
24-25,1988 in San Francisco, California. Chemical, biological, and physical treatment
technologies were addressed; monitoring strategies and containment technologies were
discussed; and fate and transport of wood preserving contaminants in soil and groundwater
were considered.
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SECTION 2
STATUS OF CERCLA WOOD PRESERVING SITES
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SECTION 2
STATUS OF CERCLA WOOD PRESERVING SITES
A phone survey was conducted by PEI Associates, Inc. to determine the status of
fifty-five CERCLA wood preserving sites either proposed or currently listed on the NPL.
Remedial Project Managers (RPM's) from eight EPA regions known to have wood
preserving sites were interviewed to determine waste types, environmental media affected,
current status, and nature of remediation that has been proposed or implemented at each
site. The information from this survey is summarized in spreadsheet form in Figure 1.
EPA Regions ID, IV, V, VI, Vm, and IX have the greatest number of CERCLA
wood preserving sites. Of these, Regions IV and VI are in the most advanced stages of the
Superfund process; most of the sites in these regions have a completed Record of Decision
(ROD). The predominant waste types encountered are creosote and pentachlorophenol
(PCP); the principal contaminants in creosote wastes being polycyclic aromatic
hydrocarbons (PAHs). Some sites also are contaminated with dioxins and metals such as
chromated copper arsenate (CCA) and ammoniacal copper arsenate (ACA). These wastes
are found to be contaminating both groundwater and soil, and in some cases, surface
water, lagoons, and river sediments.
Nearly half the sites surveyed have implemented some type of remediation either
temporarily (e.g. containment) or as part of the Remedial Investigation/Feasibility Study
(RI/FS) or Remedial Action (RA) phases of the Superfund process. Soil bioremediation
including treatment is indicated for one-third of the thirty-two sites that have indicated a
proposed remediation; incineration of soil and sludges accounts for another third; and
various soil technologies such as excavation and removal, soil washing, and
solidification/stabilization make up the difference. In terms of groundwater, pump-and-
treat technology accounts for eighty percent of the thirty-one sites for which a proposed
remediation has been indicated. However, technologies such as in-situ bioremediation are
being considered for groundwater remediation in some cases.
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Figure 1. Wood Preserving Sites on the Superfund List
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SECTION 3
FORUM SUMMARY
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SECTION 3
FORUM SUMMARY
The following presents a brief summary of each speaker's presentation. The
technical papers are presented in Section 4 of the proceedings. Handouts, copies of
overheads, slides, and other supplementary material corresponding to several speakers are
included in the Appendices.
Opening comments were made by Ronald Wilhelm of the Office of Solid Waste and
Emergency Response (EPA-OSWER) in Washington, D.C. and John Kemmerer of EPA-
Region IX in San Francisco, California. Mr. Wilhelm explained that the forum was
developed at the request of Region IX and that the intent was to provide an informal
technical workshop for EPA personnel involved in remedial actions at wood preserving
sites. Mr. Wilhelm reported that funding for the forum was provided by the U.S. EPA
Program Office in support of Superfund Technical Assistance. He also mentioned that
proceedings of the forum would be published and used as the basis for development of
future technical training and a technical resource document for RPM's assigned to wood
preserving sites. Mr. Kemmerer welcomed the attendees of the forum to Region IX and
noted that the problem of remediating wood preserving sites was common to all EPA
regions. He also thanked Ron Wilhelm, John Matthews of EPA-RSKERL and Carole
Lojek of PEI Associates, Inc. for their assistance in bringing the forum to Region IX.
Dr. Gary McGinnis of Mississippi State University presented a brief overview of
wood preserving wastes and the wood preserving industry. Dr. McGinnis explained that
wood preserving sites in the United States are located geographically in two wood-growing
bands: one in the east/southeast, and one in the west/northwest Wood preservatives are
used to prevent microbial degradation and decay from termites and other wood parasites.
The most common use of preserved wood is for railroad ties, telephone poles, piers, and
other types of construction lumber. Dr. McGinnis explained that chemicals used in wood
treating are comprised of two distinct groups: oil-borne or organic wood preservatives (e.g.
creosote and PCP), and water-borne preservatives (e.g. copper, chromium, arsenic, and
zinc). These chemicals are commonly introduced into the wood in cylinders at high
temperatures and pressures. Dr. McGinnis also discussed the environmental media
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affected (i.e. groundwater, soil, air) and the associated contaminants which are commonly
found in these media at wood preserving sites.
Alfred Kornel of EPA-RREL in Cincinnati, Ohio made a presentation on the
destruction of chlorinated dioxins, furans, and other halogenated aromatics found in soil
and groundwater using chemical reagents prepared from polyethylene glycols and
potassium hydroxides (KPEGs). Bench scale tests using these reagents have successfully
demonstrated the dehalogenation of polychlorinated biphenyls (PCBs) to less than 1 ppm
and chlorinated dibenzo-p-dioxins (PCDDs) and chlorinated dibenzofurans (PCDFs) to less
than lppb. Field testing of this treatment technology was initiated in January 1986 at the
Montana Pole and Treating site near Butte, Montana. Concentrations of PCDDs and
PCDFs (1000 ppm) contained in 9000 gallons of waste oil were successfully reduced to
non-detectable levels at this site. Mr. Komel also summarized field test results using alkali
metal polyethylene glycolate complexes (APEG) at the U.S. Navy's Public Work Center in
Guam. Approximately 30 tons of soil at this site is contaminated with PCBs (2500-4500
ppm) which resulted from the process of rebuilding transformers and capacitors. Results
of field-scale pilot tests indicate PCBs in contaminated soils (600-3000 ppm untreated) at
this site were successfully reduced to less than 1 ppm.
Dr. Herbert Ward of Rice University in Houston, Texas spoke about in-situ
biodegradation of both soluble and nonaqueous phase organic pollutants in groundwater as
applied to wood preserving sites. In-situ biorestoration refers to the stimulation of
indigenous subsurface microorganisms using limiting nutrients and oxygen to aerobically
degrade organic pollutants. Dr. Ward stressed that successful employment of this process
is site-specific and depends on availability of the following factors: adaptive microbes,
specific aquifer characteristics, aerobic conditions, electron acceptor (oxygen, peroxide,
nitrates), nutrient enrichment, acceptable toxin levels for the microbes. Subsurface
microbes characteristically are: very small in size; widely available; highly active;
oligotrophic; mostly prokaryotes (e.g. bacteria).; geologically very old; associated with the
soil matrix; and randomly distributed. Dr. Ward also reviewed the results of a field study
at the United Creosoting Company site in east Texas.
Dr. Ronald Sims of Utah State University, who is currently on sabbatical at the
EPA-RSKERL in Ada, Oklahoma, spoke about onsite bioremediation of wood preserving
contaminants in soils using various approaches such as land treatment, suficial in-situ,
subsurface in-situ, and bioreactors. Dr. Sims listed eleven CERCLA wood preserving
sites where some mode of bioremediation has been proposed. Degradation,
transformation/detoxification, and immobilization are three key concerns in bioremediation.
Dr. Sims explained that bioremediation involves the intermingling of principles from three
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disciplines: molecular biology, ecology, and engineering. Molecular biology entails
utilizing microbes which display an active and diverse metabolism. Ecology involves the
determination of factors that stimulate or limit microbial growth and activity such as pH,
salinity, synthetic chemicals, osmotic pressure, radiation, and physiological barriers.
Engineering as applied to bioremediation relates to parameters such as toxicity, rate of
biodegradation, rate of transport to the groundwater, and characteristics of the breakdown
products. Dr. Sims also reviewed results of successful pilot scale studies involving land
treatment at the Burlington Northern site in Brainerd/Baxter, Minnesota.
Donald Oberacker of EPA-RREL in Cincinnati, Ohio discussed the applicability of
incineration as a remedial technology for wood preserving wastes with the exception of
those sites having significant concentrations of heavy metals. Mr. Oberacker presented
existing data on four incineration trial burns of wood preserving wastes such as PCPs and
creosote. A study conducted for the Department of Defense involving incineration of
wooden ammunition boxes treated with PCP resulted in non-detectable levels of dioxins or
furans in the stack. Studies conducted for the EPA-Office of Solid Waste (EPA-OSW)
involving incineration of PCP and creosote contaminated bottom sediment/sludge from
wastewater treatment at the Allied Chemical plants in Alabama and Mississippi resulted in
non-detectable concentrations of dioxins, furans, and all priority RCRA volatile and semi-
volatile compounds in the ash. Stack test results for the Mississippi plant were unavailable,
however, verbal reports of stack test results from the Alabama plant indicate non-detectable
levels of dioxins or furans. In a series of EPA tests conducted at thirteen facilities, results
from one facility, Anderson Windows, where PCP treated wood containing PVC was
incinerated, indicated small amounts of dioxins and furans in the stacks and ash. In this
case, however, the variability of incinerator chamber temperatures at the facility may have
been the cause. Mr. Oberacker also presented a description of hardware and specifications
used for mobile/transportable hazardous waste incineration for field site cleanup operations.
Dr. Joseph Keely of Portland, Oregon spoke about the design criteria and operation
of pumping well systems as a remedial technology for groundwater at hazardous waste
sites. Dr. Keely stressed the importance of optimizing pumping strategies by considering
such critical factors as well construction, aquifer conditions, hydrogeology, demographic
constraints, and the physiochemical properties of the contaminant (e.g. dispersion,
sorption, ion exchange, etc.). A common type of groundwater remediation involves the
use of injection and extraction wells to induce stabilization of a contaminant plume. A
contaminant plume may be temporarily or permanently immobilized to allow far withdrawal
and above ground treatment; to allow delivery and recovery of products and reactants for
in-situ subsurface biotreatment; or to allow for future development of newer treatment
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technologies. Dr. Keely also discussed pulsed pumping vs. continuous operation of an
extraction-injection wellfield. Pulsed pumping involves cyclic operating and nonoperating
phases of extraction or injection wells. One reason for this pumping strategy is to allow
time for diffusion and contaminant movement from low permeability zones to high
permeability zones. In addition, rapid flow rates during remediation may not allow time for
sorbing compounds to build up to equilibrium concentrations or for non-aqueous phase
residuals to dissolve into the groundwater. By allowing time for these processes during the
nonoperating phases, pulsed pumping increases the concentrations of contaminated
groundwater removed during the operating phases. In closing, Dr. Keely stressed that
pump-and-treat technology is not a proven technology but an accepted one and that realistic
goals must be set when using this technology.
Thomas Sale of CH2M Hill in Denver, Colorado made a presentation on in-situ soil
washing and flushing technologies, including primary and enhanced recovery systems as
applied to creosote oils. Primary oil recovery will only recover a fraction of the oil; one-
third of the pore space contains oil that can be displaced under waterflooding. This residual
oil is very difficult to displace because the interfacial tension between water and oil prevents
movement through pore spaces. Primary oil recovery involves pumping fluids through a
formation where oil concentrations are above the residual saturation using a fluid recovery
system such as wells, trenches, or drain lines. Mr. Sale presented a case study from the
Baxter/Union Pacific Tie Treating plant in Laramie, Wyoming. In this field pilot study
10,000 gallons of creosote were recovered from a two feet thick zone using drain line
systems at a depth of 12 feet over an area with a 50 foot radius. During a system scale up,
100,000 gallons of creosote were recovered from a two acre area. Mr. Sale stressed that
the success of water flooding may be limited by the presence of differential permeabilities
due to heterogeneities in the formation, thus the application of primary recovery technology
is very site specific. Of the various enhanced recovery methods available to date, only
surfactant-assisted flushing can be successfully applied to creosote oil at wood preserving
sites. A surfactant is a surface active agent which accumulates along the oil/water interface,
reduces interfacial tension between fluids and allows oil to move more readiliy through a
solid formation. Surfactant-assisted flushing combines water flooding technology with the
use of surfactants to provide enhanced recovery where oil concentrations are at residual
saturation.
Frank Freestone of the Office of Research and Development (EPA-ORD) in Edison,
New Jersey talked about physical separation for excavated soils and in-situ vacuum
extraction technologies. Physical separation addresses particle size and mineralogical
considerations such as the tendancy of an organic to adsorb onto the surface of a grain or
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into the interstices of a laminar clay. This technology involves the use of a trommel screen
or drum washer to separate sands from clays, silts, and humic materials. After separation
the sand sized fraction should be clean enough to be replaced on the site, while the finer
particles (<25 microns) which contain the vast majority of contamination must be
remediated further using some other technology such as incineration. Soil test results from
the site of a fuel oil spill at the Naval Air Station in Lakehurst, New Jersey indicated that
99% of the contamination was contained in the finer grained material (<25 microns). In a
pilot scale test conducted at this site, sands and clays which initially contained 3.6% oil and
grease underwent a 99% removal; only 1% oil and grease remained in the residual soil. In-
situ vacuum extraction involves the removal of soil gas by putting a vaccuum on a system
of extraction wells, drawing gases through the soil, and subsequently separating the
organics out A program demonstration was conducted at a site in Groveland,
Massachusetts where TCE was used as a degreasing solvent and is the principal
contaminant in the soil. Four extraction wells and four monitoring wells were installed at
the site. After 56 days of soil-gas extraction, there was a substantial reduction of TCE
levels in soil gas samples from all four wells. Mr. Freestone pointed out that soil-gas
extraction is a viable technique for wastes having a low molecular weight (e.g. TCE) but is
probably not applicable to high molecular weight wastes.
Jeffrey Rosenfeld of Lockheed Engineering, which provides technical assistance to
the Environmental Monitoring Systems Laboratory (EPA-EMSL) in Las Vegas, Nevada
presented a talk on monitoring strategies for groundwater contaminants at wood preserving
facilities. Mr. Rosenfeld was involved in a study in which 126 organic priority pollutants
in groundwater from five creosote sites across the country were compared. The purpose of
this study was to determine organic compounds which are common to the wood preserving
industry and to use this information in developing monitoring strategies for these sites.
Based on this comparison, the most commonly detected volatiles are simple aromatic
compounds and the most commonly detected semi-volatiles include phenolic compounds
and PAHs which are the two major constituents of creosote. Further analysis of these
results indicate that concentrations of these compounds are determined by four factors:
solubility, adsorption, chemical reaction, and biodegradation. Mr. Rosenfeld noted the
consistency of chemical detection across the five sites and concluded that only 27 of the
126 organic priority pollutants are detected in the groundwater. PCPs, PCBs and
pesticides were generally not detected; it is assumed that none of these compounds were
extensively used in the wood preserving process at these sites. Likewise, results of a study
to determine inorganic indicators (e.g. arsenic, chromium, and copper) for wood treatment
sites were inconsistent because inorganics played a very small role in the preserving
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process at these sites. In summary, a monitoring strategy for wood treatment sites should
emphasize the semi-volatile compounds, and also the highly mobile volatiles. It is also
important to know the type of process used at the site to determine whether metals should
be monitored. Teflon or stainless steel casing is recommended for wood treating sites;
PVC should not be used since there is potential for organic compounds to degrade or to
react with the material. Groundwater sampling should be done at the top of the aquifer to
monitor floaters, but it may also be necessary to sample at the bottom of the aquifer to
monitor sinkers such as creosote.
Dr. Robert Ambrose of the Office of Research and Development (EPA-ORD) in
Athens, Georgia addressed fate and transport modeling of wood preserving contaminants
in surface water. Mr. Ambrose conducted a risk assessment to estimate the risk of PCP
entering surface water due to drippage from a wood drying site. The models for this
assessment were based on laboratory and field data from Heath Creek, an actual location
near Rome, Georgia. Three chemical pathways in a surface water system were modeled:
contaminant loading to the stream; upstream flow dilution; and bioaccumulation.
Contaminant loading to the stream was modeled using an unsaturated zone model called
PRISM. This model was used to predict water pathways, sediment pathways, and
pollutant leaching in terms of average loads of runoff, erosion, and leaching. Upstream
flow dilution was modeled using the pesticide root zone model which calculates stream
concentration due to erosion, runoff, and leaching. The food and gill exchange of toxic
substances model (FGETS) was used to predict the bioaccumulation in the fish. FGETS is
a dynamic model which looks at daily changes in water concentration, and the change in the
weight of the fish versus time (fish growth). Based on the results of this modeling, the
average concentration of PCP in a sculpin fish over the course of its lifetime was
determined to be 24 ppb. When this fish was fed to a trout to simulate the food chain
effect, the whole body concentration running average of the trout was measured at 43 ppb;
without the food chain effect this concentration was 40 ppb. All of these results are well
below the drinking water standard for PCP (220 ppb).
Dr. Walter Grube of EPA-RREL in Cincinnati, Ohio made a presentation on
capping or cover systems as a remedial technology at wood preserving sites. Dr. Grube
reviewed several publications which are useful reference guides in the design, operation,
and maintainence of cover systems for CERCLA and RCRA hazardous waste sites. Cover
systems are used primarily in humid climates for the prevention of precipitation and
infiltration. In more arid climates, cover systems are intended to provide protection against
burrowing rodents and to prevent radon loss from the underlying wastes at uranium tailings
sites. A typical multiple layer cover system includes a barrier soil layer or biotic barrier, a
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lateral runoff or drainage layer, a vegetative layer, and a foundation layer or traffic surface.
Dr. Grube stressed the importance of quality control/quality assurance in the construction
phase of cover system design. Affects of freeze and thaw conditions on the integrity of
compacted clay soil must be considered. The performance and integrity of a multilayer
system having surficial structures such as monitoring wells must be evaluated.
Compatibility tests must be conducted on liners to determine if leachate on the compacted
soil will undergo physical or geochemical alteration that may compromise the liner
integrity. As an example of the wide acceptance of multilayer cover systems, Dr. Grube
presented a hazardous waste landfill in Hamburg, West Germany where experimental cover
designs are incorporated into the actual remedial cover. Monitoring gas collection,
infiltration and leachate collection are also conducted at this site.
Edwin Barth of EPA-RREL in Cincinnati, Ohio discussed the applicability of
stabilization/solidification (or immobilization/fixation) technology to metals in soils and
sludges at wood preserving sites. Solidification is the process of converting a non-solid to
a solid; this process does not necessarily prevent leaching. Stabilization involves a
chemical reaction such as precipitation, complexation, and organic binding which is used to
decrease leaching. Stabilization/solidification (S/S) technology is advantageous to many
other technologies because it is relatively inexpensive and has gained public acceptance. In
general, lead, nickel, zinc, copper, cadmium, chromium DI, and low-level organics may be
better stabilized than arsenic HI, arsenic V, chromium VI, mercury, and high-level
organics. However, each unique soil matrix will dictate the feasibility of stabilization. It is
important to note that the presence of sulfates, nitrates, phenols, and oil & grease will
interfere with the S/S process. Mr. Barth reviewed the soil characteristics which impact
S/S, the variables and types of leaching/extraction tests to use, and the various physical
tests that S/S is subjected to. S/S technology may be applicable to wood preserving sites
contaminated with copper and chromium but may be less effective for wastes containing
arsenic and PCP. There are currently some CERCLA wood preserving sites which are
evaluating S/S as a remedial technology. Mr. Barth presented data from a S/S pilot study
conducted at the Whitehouse, Florida Superfund site. Organic material in soil at this site
was stabilized with an organophilic clay. After stabilization, soil analysis using the
Toxicity Characteristic Leaching Procedure (TCLP) resulted in non-detectable
concentrations of four semi-volatile compounds.
Dr. Walter Grube of EPA-RREL also presented an overview of containment
technologies such as slurry walls which are being used at some wood preserving sites. A
slurry wall is a positive impervious barrier which is constructed to interface with a natural
impervious layer or aquitaid thereby preventing further migration of leachate. In
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constructing the slurry wall, a trench is dug with a backhoe and a bentonite/water
suspension is introduced in order to maintain the open ditch. Ultimately the ditch is
backfilled with an impervious or low permeability barrier usually obtained by mixing the
bentonite from the slurry trench with soil excavated out of the trench. Geomembranes can
be also be used in conjunction with the soil/bentonite backfill mixture. Sluny walls are
typically proposed at hazardous waste sites which have a high groundwater table, highly
unconsolidated pervious soils, a sufficient groundwater gradient to drive the pollutants; and
a groundwater sink such as a river, pond, or ocean. As pan of their remedial technology,
wood preserving sites may be "boxed in" with slurry walls designed to reduce groundwater
inflow and to hold the contaminants on site. In most remedial designs a slurry wall is
constructed to contain the contaminant area for improved efficiency of a treatment process
being applied; its use is typically not meant to be a permanent solution. Dr. Grube
reviewed an example of slurry wall technology at the Gilson Road-Sylvester Site in
Nashua, New Hampshire. At this site, the slurry wall system includes 4000 feet of slurry
wall, recovery wells to pump the groundwater, and recharge trenches to reinject the treated
material.
At the conclusion of the presentations, an informal roundtable discussion was
conducted to provide a forum for additional concerns and questions which were not
addressed during the talks. Summary comments were made by John Matthews and Ronald
Wilhelm. Mr. Matthews expressed his gratitude for having the opportunity to provide
technical transfer on the remediation of wood preserving sites to the Regional EPA offices.
He thanked the individuals from EPA Headquarters, the Technology Centers at the EPA-
ORD Laboratories, and PEI Associates, Inc. who were involved in the combined effort to
present the forum. Mr. Matthews also mentioned that proceedings from the forum would
be compiled and distributed to all attendees. Thomas Pheiffer of EPA-OSWER in
Washington, D.C. requested that the attendees provide him with feedback on the forum so
that funding for additional technical transfer programs can continue to be matte available.
Ronald Wilhelm thanked all the speakers and the regional representatives for attending and
reiterated that the material presented during the forum would be used as the basis for a
training package for RPMs.
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SECTION 4
FORUM PRESENTATIONS
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OVERVIEW OF THE WOOD PRESERVING INDUSTRY
Dr. Gary D. McGinnis, Mississippi State University
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OVERVIEW OF THE WOOD-PRESERVING INDUSTRY
Gary D. McGinnis
Professor of Wood Science & Technology ana Chemistry
Mississippi Forest Products Utilization Laboratory
Mississippi State University
Mississippi State, MS 39762-5724
Wooa preserving in the United. States is a hundred-year-old
industry. Wood is treated under pressure in cylinders with one of four
types of preservatives: creosote; pentachlorophenol in petroleum; water
solutions of copper, chromium, and arsenic; and fire retardants.
Because of past practices, many sites have relatively large amounts of
sludges, contaminated soil, and in most cases contaminated ground
water. This presentation will describe the chemical composition of the
organic wood preservatives, the avenues by which these chemicals are
getting into the environment, and the current methods used by
the industry to clean up contaminated soil, sludges, and ground water.
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OVERVIEW OF THE WOOD-PRESERVING INDUSTRY
By
Gary D. McGinnis
Professor of Wood Science & Technology and Chemistry
Mississippi Forest Products Utilization Laboratory
Mississippi State University
P. 0. Drawer FP
Mississippi State, MS 39762-5724
January 1989
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TABLE OF CONTENTS
Page
History 1
Size and Location 2
The Process 4
Organic Chemicals Used to Treat Wood 8
Type of Environmental Contamination at Wood-Treating Sites. ... 10
Chemical, Biological, and Photochemical Changes in Wood-Treating
Chemicals in the Environment 13
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OVERVIEW OF THE WOOD-PRESERVING INDUSTRY
History
For centuries, wood has been treated with various organic and
inorganic compounds to make wood last longer against the destructive
forces of nature. Various chemical systems have been developed to
protect wood from the effects of insects, fungus, marine organisms,
fire, chemical degradation, and weather.
Processes for extending the life of wood had been developed before
the birth of Christ. The Chinese used salt water to extend the life of
wood. Persians and Romans used olive oil on bridge timbers to increase
service life. In 1716 a patent was issued to Or. William Cook to treat
ship planking against shipworms and decay with tar oil. In the early
nineteenth century, a U.S. patent was issued to Kyan, Burnett, and
Bethell for treatment with tar oils. In 1848 the first inorganic salt
preservative plant was built to treat timbers for the docks and canals
on the Merrimac River in Massachusetts, and in 1865 the first Bethell
plant to pressure treat creosote railway material was built. In 1875
the first major plant, and one that is still operating, for treatment of
railroad piles, timbers, caps, and ties with creosote was built by the
Louisville and Nashville railroad in West Pascagoula, Mississippi. A
large number of plants were started in the early 1900*s to treat
railroad crossties, and by 1930 almost all crossties were treated with
creosote before placement in service. A major change occurred in the
industry when the chestnut blight of 1915 killed the chestnut trees, the
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2
softwood species of southern pine and Douglas fir took over for use as
utility poles. A large number of plants were started to pressure treat
these materials.
Size and Location
From the beginning the wood-treating industry in the United States
has been a relatively simple, low-product cost, small family-owned
operation. In the 1930's some of the now larger companies treating with
oil preservatives began to emerge, but even today most of the companies
are still a one or two plant operation. In the future with the current
environmental regulations, many of the small companies will not survive,
and the industry probably will be dominated by new and the larger
companies. A new company would have a major economic advantage since
the plant could be designed so that environmental costs would be minimal
and the company would not be liable for the tremendous cost of clean-up
of past environmental practices before environmental regulations come
into effect.
Figure 1 shows the location of the plants in the United States. In
1978 there were 631 commercial plants in operation; currently, there are
considerably fewer due mainly to the cost of environmental clean-up.
The majority of plants are located along the eastern seaboard, across
the southeastern United States, and in the Pacific Northwest. The
majority of sites generally correspond to the forested areas of the
United States.
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Figure 1. Location of wood treating plants in the United States.
Co
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4
The Process
The current wood-preserving process used in the United States is
primarily for the protection of wood against decay and insects. A small
percentage is treated with fire retardants. There are two broad groups
of chemicals used to preserve wood—oils and oilborne preservatives and
the waterborne preservatives (Table 1). The oilborne preservatives are
mainly organic while the waterborne preservatives are mainly inorganic
salts.
When logs are brought to the wood-treating plant, the initial step
in the wood-treating process involves removing the bark. After
debarking, the moisture content of the wood is reduced by air-drying,
kiln-drying, or by drying directly in the pressure vessels used to treat
the wood with the preservative. This latter technique removes the water
from the wood by either steaming the wood in the retort, heating it in
oil under reduced pressure, or by exposing it to hot vapors of organic
solvents in a process called vapor drying.
After drying the wood is ready to be treated with the wood
preservative. Preservative impregnation can be accomplished by either
pressure or non-pressure methods. Currently, 95% of all preservative
treated wood products are produced using pressure impregnation. The
pressure processes typically are done using pressures of 50 to 250 psi
depending on species of wood. Preservative temperatures employed during
the treating cycle vary with the preservative used. Creosote and its
solutions are normally applied at temperatures of 210° to 230°F. The
temperature used with pentachlorophenol solutions varies with the
solvent and may range from ambient to 220°F. With one exception, all
waterborne preservatives are applied at ambient temperature. Creosote
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5
Table 1. Chemicals used in wood treatment.
A. Organic Wood Preservatives (Oils and Oilborne Preservatives)
1. Creosote
2. Pentachlorophenol (4-8%) in a heavy oil
Pentachlorophenol in a volatile solvent
B. Waterborne Preservatives
1. Combination of copper, chromium and arsenic salts
2. Combination of zinc, copper and arsenic
3. Combination of ammonia and metal salts
4. Combination of dinitrophenol, zinc and other metal salts
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6
may be applied in undiluted form or diluted with coal tar or petroleum.
Pentachlorophenol is applied in a solvent of low volatility such as a
heavy oil or in a volatile solvent such as mineral spirits, methylene
chloride, or liquefied petroleum gas.
At the completion of the pressure cycle, a final vacuum is applied
to remove most of the free liquid on the surface. The wood is moved
from the treating cylinder, generally on railroad tracks, to drip pads
where the excess chemicals are allowed to drip onto the ground. In most
cases the logs are moved to log storage areas. The purpose of storing
logs on log storage areas is not only to provide an inventory of
material but also in the case of the waterborne preservatives, to
decrease the moisture content and therefore reduce shipping costs.
The type of and relative amount of treated wood products produced
in 1978 are shown in Table 2. The major products are railroad ties,
poles, and lumber. The major wood preservative is creosote. The
oilborne preservatives make up 72% based on volume of products or 81%
based on weight of the preservative used. Currently, based on personal
observation, the use of the waterborne preservative usage has increased
substantially relative to the other two preservatives. This increased
use of waterborne preservatives is due partially to environmental
considerations. The waterborne preservatives require water as a solvent
(in other words are not water users) while the oilborne produce large
amounts of sludge as well as contaminated process water. Both of these
fractions must be treated before they can be discharged. A more
detailed description of the waste produced during wood treatment is
given in a later section of this paper.
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Table 2. Volume of treated wood in 1978 (2).
Treated With
Waterborne
Products All Creosote Preservatives
Preservatives13 Solutions Penta (CCA/ACA/FCAP)
r 1,000 cu. ft.
Crossties and
switch tiesc
106,085
103,138
449
2,498
Poles
64,179
18,237
41,905
4,038
Crossarms
1,685
41.0
1,615
29
Piling
12,090
9,993
1,154
943
Lumber and timbers
105,305
10,779
21,209
73,317
Fence posts
20,028
4,584
10,983
4,461
Other products'*
18,113
7,815
2,681
7,616
All products 327,485 154,587 (123.7)e 79,996 (40.0)f 92,903 (37.2)f
aVolume reported for 1978 (AWPA), plus volume reported by respondents to Assessment Team
Survey, plus volume estimated for nonrespondents.
^Creosote, penta, and CCA/ACA/FCAP only.
^Includes landscape ties.
"Includes plywood.
Note: Components may not add to totals due to rounding.
^Treating solutions in million gallons.
Treating solution in million pounds.
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8
Organic Chemicals Used to Treat Wood (3)
The majority of chemicals used to treat wood are used to preserve
wood from decay and insects. Since the oilborne preservatives (organic
preservatives) are the major components in this group (Table 2) and
because of their greater environmental problems, they will be the only
group that will be discussed in this section.
Technical grade pentachlorophenol used for treating wood contains
85 to 90% pentachlorophenol (Fig. 2). The remaining materials in
technical grade pentachlorophenol are 2,3,4,6-tetrachlorophenol (4-8%),
"higher chlorophenols" (2-6%), and dioxins (0.1%). The tetrachloro-
phenol is added to pentachlorophenol to increase the rate of
solubilization. "Higher chlorophenols" are formed during the
manufacturing of pentachlorophenol and consist of two or more fused
aromatic rings linked by oxygen or carbon bridges. There are a
relatively large number of different "higher chlorophenols" in technical
grade pentachlorophenol.
There is approximately 0.1% dioxin in technical grade
pentachlorophenol. The dioxin which makes up over 90% of this fraction
is octachlorodibenzo-p-dioxin. There are also traces of the hepta and
hexa isomers. None of the very toxic 2,3,7,8-tetrachlorodibenzo-p-
dioxin has been found in pentachlorophenol produced in the United
States. Manufacturers of pentachlorophenol in the United States have
been able to lower the levels of hexachlorodibenzo-p-dioxins in
technical grade pentachlorophenol to the 1 ppm levels recently by
modifying their manufacturing processes.
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9
OH
Cl"^5y^Cl
CI
Pentachlorophenol
85-90%
OH
C1
CI
CI
2,3,4,6-Tetrachloro phenol
4-8%
Cl
Higher Chlorophenols
cs 0.1%
CI CI
D i o x i n
(octa-, traces of hepta-,
and hexachlorodioxin )
Figure 2. Composition of technical grade pentachlorophenol.
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10
Creosote is an even more complex mixture of chemicals produced from
coal by destructive distillation. The major components are polynuclear
aromatic hydrocarbons (PAH's). Over 274 individual compounds have been
identified in creosote. The concentration and structure of some of the
major components found in creosote are shown in Table 3 and Figure 3.
Types of Environmental Contaminations at Wood-Treating Sites
The major sources of hazardous waste from the wood-treating process
occurs during the treatment cycle. Oilborne preservatives mix with
water to form a contaminated process water. The major source of water
is from the wood; smaller amounts come from steam leaks in the treatment
system and rainwater. Prior to the environmental rules (before 1970's),
the waste water was treated and then sent to surface drainage or a
stream. A large number of the plants had sumps or ponds to trap the
heavy oil residuals before discharging to a creek or to a public-owned
treating works (POTW). Ponds ranged from less than 1 to 4 or more
acres. Normally, none of the ponds were lined with anything but the
local soils.
Many of the older plants treated the waste water before sending it
to ponds using a primary oil/water separator. Flocculation or
adsorption of the wood-preserving oils by the addition of clays, resins,
alum, lime, or polymers is sometimes used as a secondary wastewater
treatment process after primary oil/water separation. Currently, most
oilborne plants use both a primary oil/water separation treatment
followed by a secondary treatment using polymeric materials to lower the
levels of oil in the water. The solid sludge obtained (K001 Hazardous
Waste) is shipped to Hazardous Waste Storage Facilities while the water
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11
Table 3. Major components of creosote (2).
Creosote component % Whole creosote
Naphthalene
17.0
2-Methylnaphthalene
6.5
1-Metnylnaphthalene
3.5
Biphenyl
1.9
Acenaphtnylene
0.5
Acenaphthene
7.8
Dibenzofuran
5.2
F1uorene
6.0
Phenanthrene
19.4
Anthracene
2.52
Carbazole
5.1
Fluoranthene
11.8
Pyrene
8.4
1,2-Benzanthracene/Chrysene
4.2
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Pyrene
Figure 3. Structures of the major components of creosote.
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13
can be sent directly to a POTW, or it can be further treated by
biological treatment and/or carbon treatment at the wood-treating site
and sent to a POTW, or recycled using the water as make-up water for
waterborne preservatives.
Although waste water and sludges produced by treatment of the waste
water are of major concern to the environmental agencies, they are not
necessarily the major environmental problem at wood-treating sites.
Most sites have both ground water contamination and large amounts of
contaminated soil. Large amounts of contaminated soil are found around
and below the ponds (or former ponds) used to store the waste water and
sludges. Contaminated soils are also found around the treating
cylinders and the track areas due to drippage from the treated material
as it is moved from the treating cylinders to storage areas. Another
source of contamination is the areas around the storage, treating, and
unloading tanks due to minor preservative spillage from broken pipes,
bleeding of treated wood, etc. These areas can be rather large,
especially in the older railroad and pole plants.
Chemical, Biological, and Photochemical Changes in Wood-Treating
Chemicals in the Environment (3-6)
In general, when chemicals are put in the environment, several
processes can occur. The sample can undergo decomposition; it can be
lost by direct volatilization into the air, or it can migrate through
the soil into the ground water. The relative occurrence of each of
these processes depends on many factors, including the physical and
chemical properties of the chemical, the physical and chemical
properties of the soil or water, and other environmental effects (amount
of wind, amount and direction of water movement, etc.). At most sites
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14
the largest amount of contamination is found in the soil, so the
following discussion will be limited to the changes occurring in the
soil.
Three major types of decomposition reactions occur in the soi1 --
photochemical, chemical, and microbiological. The photochemical process
is initiated by ultraviolet radiation from sunlight. Both
pentachlorophenol and creosote are degraded -by sunlight, and this
reaction is very important in water contaminated with these materials.
However, in soil this reaction is much less important since it occurs
only at the surface of the soil.
Chemical decomposition in soil or water, such as air oxidation or
hydrolysis of weak bonds, is not an important reaction with these two
groups of chemicals since they do not have any groups that are easily
oxidized or hydrolyzed.
With both creosote and pentachlorophenol, microbiological
decomposition is the major process occurring in soil. There have been a
large number of studies on the breakdown of pentachlorophenol in soil.
Figure 4 summarizes the sequence of reactions that have been shown to
occur. In soil, pentachlorophenol undergoes a reversible methylation
reaction to form pentachloroanisole, but this reaction apparently is not
part of the main decomposition pathway. The main route for
decomposition is not through the methyl derivative, but through
pentachlorophenol. The route of decomposition involves dechlorination
leading to a series of partial dechlorinated products, such as 2,3,5,6-
tetrachlorophenol. The second general step in the decomposition
reaction involves an oxidation step to form substituted hydroquinones or
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15
OCHj
av^va
CI-^5yAci
Esterif ication
Reaction
C(
OH
OH
Civ^vCl dechlorination
d^JUl Cl-^
CI
CO, + CI"
COOH
H°°C ^-ci
ci-^y^ci
ci
mono-,di-,
and
trichlorophenols
Oxidative
Process
OH
HO>j-^\-CI
CI-W/^CI
CI
Figure 4. Microbiological decomposition of pentachlorophenol.
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16
catechols, such as 2,3,4,5-tetrachlorocatechol. The oxidation product
then undergoes ring cleavage, ultimately forming C0£ and inorganic
chloride ions.
The factors that are important on the rate of degradation of
pentachlorophenol in soil are organic content of soil, moisture content,
clay content, and type of bacteria and its population. Another factor
is the oxygen content of the soil. Pentachlorophenol is broken down
under aerobic and anaerobic conditions; however, the oxidation step
which leads to breakdown to CO2 and inorganic chlorine is favored by
aerobic conditions.
Studies with a variety of soil types (Table 4) have shown that the
time for 90-100% breakdown varies from 21 days to 1 year. The one
exception was a study where pentachlorophenol was added to sterilized
soil in a sealed container. Under these conditions the time estimated
for complete degradation was over 5 years.
There are many types of bacteria and fungi that are capable of
degrading pentachlorophenol, including Pseudomonas, Aspergillus,
Trichoderma, and Flavobacterium. Good sources of these bacteria are
areas that have been exposed to pentachlorophenol for long periods of
time; for example, soil around telephone poles or around wood treating
plants. Regardless of where the soil is obtained, the soil bacterial
population capable of degrading pentachlorophenol can be increased by
acclimating the soil to ever-increasing amounts of pentachlorophenol.
The major components of creosote are the polycyclic aromatic
hydrocarbons (PAH's) with trace amounts of phenols and azaarenes. A
wide range of soil organisms, including bacteria, fungi, cyanobacteria
(blue-green algae), and eukaryotic algae, have been shown to have the
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17
Table 4. Degradation of pentachlorophenol in soil (1).
Degradation Special
parameter Soil type conditions Time
90% degradation
90% degradation
Complete
Effect on
growth of corn
and cucumbers
90% degradation
Complete
degradation
Complete
degradation
Complete
degradation
98% degradation
Arable layer in
rice fields (11
soils)
Forest red-
yellow soil
sublayer
Wooster silt
loam
Dry soil
Fertile sandy
loam
Mature paddy
soil
Dunkirk silt
loam
Paddy soil
Warm, moist
soil
Permeable soil
60% water
25% water
60% water
25% water
7.5 kg/ha
penta, optimum
conditions for
microbial growth
Sealed in air-
tight container
Air-dried
Medium water
Water saturated
Low organic
content
Aerated,
aqueous soil
suspension
Soil perfusion
Composted with
sludge from
wood-treating
plant
Approx. 50 days
Approx. 30 days
No degradation
in 50 days
Approx. 22 days
> 5 years
> 2 months
2 months
1 month
1 month
Approx. 72 days
21 days
> 12 months
205 days
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18
enzymatic capacity to oxidize PAH's. Prokaryotic organisms, bacteria,
and cyanobacteria use different biodegradation pathways than the
eukaryotes, fungi, and algae, but all involve molecular oxygen. Figure
5 shows one proposed mechanism for the microbiological reaction.
Generally, rates of degradation for PAH compounds decrease as the
molecular weight increases; rates of degradation are faster in soil than
water; and overall rates of degradation are faster where there is an
acclimated bacteria population. Compounds such as naphthalene,
phenanthrene, and anthracene, which are readily metabolized, are
relatively water soluble, while persistent PAH's, such as chrysene and
benzo(a)pyrene, have a lower water solubility. Exceptions exist with
pyrene and fluoranthene in that these compounds are more soluble than
anthracene and yet have not been found by some researchers to be
appreciably metabolized by soil microorganisms. Other factors that may
affect the persistence of PAH compounds are insufficient bacterial
membrane permeability to the compounds, lack of enzyme specificity, and
lack of aerobic conditions.
The fate of PAH compounds in terrestrial systems has been reviewed
by Sims and Overcash (5), Edwards (6), and Cerniglia (7). These reviews
present additional information on PAH degradation.
Currently, the industry is using a variety of methods to clean up
the waste materials at the site. At the present time, most ponds
containing K001 waste have been removed. The material has been
incinerated or sent to hazardous waste storage sites. Work on clean up
of contaminated soils and ground water is just getting started and will
be a major task for the industry. Currently, most sites are being
cleaned up using biological processes. In the case of ground water,
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Anthracene
1,2-Dihydro-1,2-
dihydroxy-anthracene
OH
COOH
3-Hydroxy-2-
Naphthoic Acid
C^COOH
iCoH
Salicylic Acid
- Cj£oh
Catechol
Figure 5. Proposed mechanism for the microbiological degradation
anthracene (4-5).
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20
pump and treat technology and carbon columns have been the most widely
used method for clean-up. In the case of contaminated soil, various
bioremediation methods have been widely used as well as off-site
storage. More detailed discussion of these results will be given in a
later section of this proceedings.
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21
REFERENCES
1. C. A. Burden, Overview of the Wood-Preserving Industry, In_
Proceedings, "Hazardous Waste Treatment and Disposal in the Wood-
Preserving Industry," Atlanta, GA, March 6, 1984.
2. U.S.D.A., Biological and Economic Assessment of Pentachlorophenol,
Inorganic Arsenicals, and Creosote, United States Department of
Agriculture Tech. Bulletin #1658-1, Nov. 1980.
3. G. D. McGinnis, Biological and Photochemical Degradation of
Pentachlorophenol and Creosote, Jjn Proceedings, "Hazardous Waste
Treatment and Disposal in the Wood-Preserving Industry," Atlanta,
GA, March 6, 1984.
4. G. D. McGinnis, H. Borazjani, L. K. McFarland, D. F. Pope and D. A.
Strobel, On-Site Treatment of Creosote and Pentachlorophenol Sludges
and Contaminated Soil, Project # CR-811498010, U.S.EPA. Robert S.
Kerr Environmental Research Laboratory 1988.
5. R. C. Sims and M. R. Overcash, Fate of Polynuclear Aromatic
Compounds (PNA's) in Soil-Plant Systems, Residue Rev., 1983,
88:1-68.
6. N. T. Edwards, Polycyclic Aromatic Hydrocarbons (PAH's) in the
Terrestrial Environment--A Review, J. Environ. Qual., 1983,
12:427-441.
7. C. E. Cernigilia, Microbial Metabolism of Polycyclic Aromatic
Hydrocarbons, In: Advances in Appl. Microbiol., 1984, 30, 30-71.
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FIELD EXPERIENCE WITH THE KPEG REAGENT
Alfred Kornel, EPA-RREL, Cincinnati, OH
-------
FIELD EXPERIENCE VITH THE KPEG REAGENT
by: Alfred Kernel
Charles J. Rogers
Harold Sparks
Hazardous Waste Engineering Research Laboratory
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
ABSTRACT
Chemical reagents prepared from polyethylene glycols and potassium
hydroxide (KPEGs) have been demonstrated under mild conditions (25° - 140°C)
to dehalogenate PCBs, PCDDs, and PCDFs with laboratory destruction efficiencies
exceeding 99.9999X. The reaction mechanism is nucleophilic substitution at an
aromatic carbon.
Bench scale 6tudies have already established conditions for PCB destruc-
tion to less than 1 ppo and for PCDDs and PCDFs to less than 1 ppb. Toxico-
logical tests have established that arylpolyglycol by-products from KPEG
reactions are non-toxic. The non-toxic property of the by-products may allow
for delisting and on-site disposal of treated materials. In July and August
1986, a 2700 gallon KPEG reactor was used in Butte, Hontana, on a wood pre-
serving site and in Kent, Washington, on a waste disposal site to successfully
detoxify PCDDs and PCDFs (120 ppb - 200 ppm) in 17,000 gallons of liquid waste
to non-detectable levels. A reactor designed to treat both liquids and solids
has been tested on selected Superfund and Department of Defense sites. These
field studies have validated conditions for destruction of PCBs, PCDDs, and
PCDFs to acceptable levels required by the regulations. This presentation will
review treatment data, regulations for treated materials,.costs, and the
potentials of KPEG for the destruction of a variety of halogenated pollutants.
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INTRODUCTION
Chlorinated dibenzo-p-dioxins (PCDDs), polychlorinated biphenyls (PC3s),
and chlorinated dibenzofurans (PCDFs) are three series of related compounds
that gained notoriety for their high toxicity and persistence in the environ-
ment. In the last few years PCDDs and PCDFb have increasingly been identified
in chemical product waste streams as well as in effluents from incineration
processes.
Most of our knowledge of PCDDs and PCBs as environmental contaminants is
associated with their occurrence in soils, sediments, combustion particulates,
and in fish. In most cases, this contamination.stems from improper waste
disposal of highly toxic PCDDs in such products as hexachlorophene or 2,4,5-
trichlorophenoxy acid herbicides (2,4,5-T, herbicide orange). The occurrence
of PCDDs in fish is considered to be the major source of these compounds in
humans. Vfhile PCDDs arise principally from dimerization of chlorophenols,
PCDFs are primarily produced from pyrolysis of PCBs.
Although the toxicological profiles with aquatic organisms are limited, it
has been determined that short-term exposure of fish to low ppb and ppt of PCB
and PCDD concentrations respectively, cause decreased growth rate, poor sur-
vival and increased mortality. PCDDs, however, are considered to be a probable
human carcinogen.
The accumulation of PCDDs, PCBs, and other toxic halogenated compounds in
the environment and living systems is a serious problem that has been well
documented. Although a great amount of work has" been done'by many groups oo
the area of direct chemical decomposition of halogenated organics, relatively
little effort has been directed toward on-site chemical detoxification.
The "cleanup" of a contaminated site, which often appears in the news
media, is not really a permanent detoxification but rather a transfer of a
toxic spill from one region to another. As an example, PCB-contaminated soi'l
along some of the highways of North Carolina has been dug up, and has only been
removed, at great expense, to another area of that state and landfilled. These
PCBs are still in the environment and will persist there until they are removed
and destroyed.
The chemical stability of PCDDs, PCBs, and other haloorganics precludes
their destruction by conventional refuse incineration methods. Most municipal
incinerators cannot achieve the high temperatures necessary to destroy these
chemicals in refuse. The surprisingly high volatilization rates-of PCBs and
other chlorinated aromatic compounds raises questions over the use of land
disposal for these materials.
_ Currently, some commercial chemical methods are available to chemically
alter or destroy PCBs and other haloorganics in contaminated oils. The chemi-
cal methods developed by Acurex, Goodyear, and Sun Ohio involved dispersion of
metallic sodium in oil or the use of sodium-biphenyl or naphthalene mixtures.
Because of the reactivity of sodium with water, some of these reagents cannot
be used efficiently to directly decompose PCDDs or PCBs in soils, sludges,
sediments and dredgings. Other chemical reactions have been evaluated for
-------
dehalogenation of environmental pollutants but have not been found to be
adaptable to field conditions (1,2,3,).
Biological treatment of PCDDs, PCBs, and other harardous pollutants is
also receiving attention. The efficacy of microbes to destroy toxic halo-
genated compounds has not been fully evaluated by U.S. EPA or independent
laboratories.
KPEC PROCESS
During the summer of 1978 a new chemical reagent was synthesized and used
to effectively dechlorinate PCB-contaminated oils (4). Since that time a
series of reagents has been prepared from potassium hydroxide and polyethylene
glycol (KPEGs) which, with heating, produce rapid dehalogenation of haloorganic
compounds (5,6,7,8).
In the KPEG reagent preparation, potassium hydroxide reacts with poly-
ethyene glycol (molecular weight approximately » 400) to form an alkoxide (see
Equation 1). The alkoxide in turn reacts initially with one or more of the
chlorine atoms on the aryl ring to produce an ether and potassium chloride salt
(see Equation 2). In some KPEG reagent formulations, dimethylsulfoxide (DMSO)
is added as a cosolvent to enhance reaction rate kinetics by improving rates of
extraction of aryl halide wastes into the alkoxide phase (6).
HO PEG + KOE > KD PEG + E20 (1)
Aryl-Cl + KO PEG > Aryl -O- PEG + KC1 (2)
In 1982, detailed investigations were initiated to determine the effects
of variable reaction parameters on the rate and extent of chemical decontamina-
tion of soils (9). This research focused almost exclusively on the direct
chemical treatment of PCDD-contaminated soil. The first field investigation,
initiated in January 1986, was aimed at identifying treatment conditions for
chemical destruction of PCDDs and PCDFs in oil stored on a wood preserving site
in Butte, Montana (10).
PURPOSE
Research and field Investigation studies were initiated In January 1986,
to determine if a chemical reagent, prepared from potassium hydroxide and poly-
ethylene glycol, could be used to treat PCDD and PCDF contaminated oil at an
industrial wood preserving site near Butte, Montana. The wood preserving site
contained approximately 9000 gallons of light .petroleum oil collected pre-
viously from groundwater over a period of two years. The oil contained 3.52
pentachlorophenol, PCDD and PCDF homologs ranging from 422 ppb of tetra-isomers
to 83,923 ppb of octa-isomers. Because of the presence of these highly toxic
chlorinated dioxins and furans, the oil could not be transported off-site for
incineration. Bringing in and operating a mobile incinerator for on-site
destruction of contaminated oil was rejected because of high costs.
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In April 1986, U.S. EPA Region 8 agreed, after a review of laboratory
data, that the chemical process, based upon a potassium polyethylene glycol
(KPEG) reagent, could be used to decontaminate the PCDD/PCDF contaminated
oil on-site.
The mobile field equipment employed to implement the previous chemical
process comprises of a 2700-gallon batch reactor mounted on a 45-foot
trailer equipped with a boiler/cooling system and a laboratory/control room
area. Heating of the raw oily waste/APEG reagent mixture was achieved by
the recirculation of the oil and reagent through a pump, a high shear
mixer, and a tubeheat exchanger which was heated using a boiler or cooled
through a series of fin-type air coolers. A schematic is shown below:
PUMP
The process was employed in July 1986, to successfully destroy PCDDs
and PCDFs (1000 ppb) in 9000 gallons of oil waste to non-detectable levels
(Table 1).
Table 1. TREATMENT OF CONTAMINATED OIL, BUTTE, MONTANA
Concentration in
Contaminants Concentration in Treated Residue (ppb)
CDD/CDF Untreated Oil (ppb) 70°C. 15 min. 100°C, 30 min. *MDC
TCDD (2,3,7,8-)
28.2
-
0.65
TCDD (total)
422
-
0.37
PeCDD
822
-
0.71
HxCDD
2982
-
2.13
TCDF (2,3,7,8-)
23.1
12.1
0.28
TCDF (total)
147
33.3
0.35
PeCDF
504
-
0.36
HxCDF
3918
4.91
0.76
HpCDF
5404
5.84
•*.•06
0C0F
6230
-
2.62
~Minimum detectable concentration^ parts per billion.
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In Kay 1987 , the KPEG was used at the request of U.S. EPA Region 7 to
destToy TCDD in 20 gallons of 2,4-D/2,4,5-T formulation stored in a 55-gallon
drum at an abandoned pesticide formulation facility in Omaha, Nebraska.
On January 22, 1987, documentation was provided to U. S. EPA'6 Director,
Office of Emergency and Remedial Response, recommending the "Establishment of
KPEG as the Best Developed Alternative Technology (BH\T) for Four RCRA
Hazardous Waste Streams: PCBs and Ethylene Dibromide; Pentachlorophenol-oil
and Spent Solvents Contaminated with Dioxins and Furans" (11). This recom-
mendation was approved in 1987 by the Office of Emergency and Remedial Response
in its Superfund cleanup efforts. Future efforts are directed at decontamina-
tion of soils, sediments, and sludges.
KPEG TREATMENT OF PCB-CONTAHINATED SOIL
In July 1987, a small KPEG reactor was transported to Horeau, New York, at
the request of U.S. EPA Region 2, and used successfully to treat approximately
400 lbs. of PCB-contamlnated soil.
The purpose of conducting the demonstration at Horeau was two fold: 1) to
confirm that the KPEG reaction is effective in a'AO gallon reactor in the
dechlorination of PCBs in soil to acceptable levels (< 2 ppm) and to gather
data that will be used to design the larger 2 cubic yard reactor which will be
jointly tested by U.S. EPA and the T.5. Navy in Guam. The results from the
Horeau field tests (Table 2) clearly demonstrated that PCBs in soil ranging
from 138 to 7012 ppm can be dechlorinated by KPEG to less than 10 ppm.
In November 1987, a new improved 400 gallon LittlefoTd mixer was pur-
chased, modified as a KPEG reactor, and will be field tested on 30 tons of soil
on the U.S. Navy's Public Work. Center in Guam. The PCB concentration in this
contaminated 6oil range from 2500-4500 ppm. Field tests with the new reactor
will commence on March 28 and will be completed by May 15, 198B.
Soil samples have been received from the Guam site, treated with KPEG and
analyzed to establish treatment conditions to lower PCBs to less than 2 ppta.
The laboratory testing and analysis for the Guam site follows.
GUAM PCB-CONTAMINATED SOIL TREATMENT AND REAGENT RECOVERY
The APEG treatment of PCB-contaminated soil is a rather straightforward
process. It consists essentially of placing the contaminated soil into a
reactor followed by a 50Z by weight portion of the KPEG reagent. After load-
ing, stirring and heating is commenced. Low speed stirring is required for
intimate contact of reagent and contaminated soil. Beating causes two major
effects, the first being distillation of water from the reaction mixture and
secondly, to Increase reaction rates.-Typically, the vat temperature of the
reactor remains near 105-110 C until the majority of water is distilled off
(30-45 minutes) after which the reactor temperature slowly rises to ca 135-
150°C. The total time for a typical reaction is from 5-6 hours.
After the required elapsed time, any condensate is removed and extracted
for residual PCBs. The flask containing the treated soil/reagent mixture is
-------
TABLE 2. TEST RESULTS FROM MOREAU FIELD DEMONSTRATION OF KPEG PROCESS
Run <1 Run f2 Run g3 Run >4
Reaction PCB n* Reaction PCB Reaction PCB Reaction PCB
time concentration time concentration time concentration time concentration
(hours) (ppm) (hours) (ppm) (hours) (ppm) (hours) (ppm)
0 138 0 756 0 7012 0 680
1.25 0.22 0.25 50.6 1 228 1 19.7
4 1.46 3.25 23 3.25 6.5
6.25 9.6 7 0.91
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cooled to 40-50°C and filtered on a Buchner funnel. An additional 25-30 =1 c:
water is slurried with the reactor contents to aid in filtration.
After filtration and partial drying to 10-201 moisture, 6an;ple6 of the
treated Boil are removed and extracted for PCS (Aroclor) determination.
Recovered reagent/water is saved for reuse on subsequent decontaainatior.
runs. In this case recovered reagent from 2-3 runs is pooled, an additional
quantity of 602 KOH solution or KOK pellets are added, and the used reagent is
added to said reactor containing the contaminated soil. The process is then
continued.
PCB ANALYSIS OF TREATED SOIL
The soil coming from the reactor is extracted for residual PCB or Aroclor
determination. This process is as follows: 10 gran aliquots of the soil are
placed into 125 ml screw-top Erlenmeyer flasks to which is added 30-35 ml of
hexane/acetone (1:10), this is placed on a gyrorotary mixer at 120-130 rpm for
one hour. The extract is carefully decanted into a 250 ml separatory funnel
through a small funnel loosly packed with glass wq.o1. This extraction is
repeated twice again using hexaDe/acetone 1:1 and- 10:1. All extracts are
combined in said separatory funnel and the extracts are washed three times with
50 ml of water. The washed remaining hexane extract is placed into a KD
apparatus fitted with a 10 ml receiver and is concentrated to ca 2-5 ml. The
equipment is internally washed with hexane ca 2-k ml and then the receiver is
removed, filled to the 10 cc level and agitated. Approximately 2-3 ml of this
sample is removed, placed into a 3.5 ml septa sealed glass sample container,
and subjected to gas chromatographic analysis, either to an electron capture
detector (EDC) or mass spectrometer (MS).
ANALYTICAL PROCEDURES
Generally,- the in-house analytical procedure analyzed for residual
Aroclor(s) via capillary GC-ECD. In this system a 30 meter 0.32 mm I.D. D3-5
column, using an SGE cold on-column injector and a electron capture detector
with Nitrogen make-up gas is employed for routine PCB analysis. However, for
the Guam PCB/KPEG process, a HP GC-MSD with related data system for the analyt-
ical work has been utilized. In this case, the GC is equipped with a split/
splitless injector set to the splitless mode. The pumping requirements of the
MSD require either use of a narrow bore capillary column .(0.22 mm I.D.), or a
jet 6eperator for use with packed columns. The narrow bore DB-5 column was
used in this work.
The MSD is set to acquire data from M/Z 250-500 over the 16 to 32 minute
range. The temperature program used for the GC is AO C for 5 minutes ramp to
180 C at 25°C per minute, hold 2.5 minutes then ramp to 280°C at 5°C per
minute, and hold 10 minutes. The total time per run is approximately 42
minutes. This method permits us to resolve the Aroclor mixture and is reliable
for as low as 10 ppm of the Aroclor mixture.
For the analytical requirements to be used for the Guam PCB detoxification
utilizing APEG, we have been requested to use the Dry Color Manufacturers
-------
Association (DCMA) PCB mixture. This mixture contains nono-thru-deca chlorc-
biphenyls, Any residual PCB peaks will be quantitated by comparison to this
mixture. For example, were a hexachlorobiphenyl to remain after soil treat-
ment, it would be quantified by comparison to the DCK\ hexachlorobiphenyl. The
maximum residual PCB levels which are permissible in this work are to be 2 ppn
per resolvable PCB component. Therefore, all PCB peaks detected after treat-
ment must be below 2 ppm (as shown in Figures 1,2,3).
CONCLUSION
As shown, the KPEG reagent has demonstrated its capability to reduce PCDDs
and PCDFs to non-detectable levels in. a variety of matrices. Further, the
reagent can be used to reduce PCB levels from the thousands of ppm occurring
from Aroclors 1248, 1254, 1260 and 1262 to levels below 2 ppm within a reason-
able time frame. This demonstrates the use of KPEG systems applicability to
these pollutants in a variety of matricies.
REFERENCES
1. Miller, J. Nucleophilic Aromatic Substitution. Elsevier Press,
Amsterdam, 1968.
2. Yoshikozu, K. and Regen, S. L. J. Org. Chea. 47, 1982, (12) 2493-2494.
3. Andrews, A., Creoonesi, P., del Buttero, P., Licondra, E. and Halorano, S.
Nucleophilic Aromatic Substitution of Cr(Co) -Complex Dihaloarenes with
Thiolates. J. Org. Chem. 1983, 48 3114-3116.
4. Pytlewski, L. L. A Study of the Novel Reaction of Molten Sodiua and
Solvent with PCBs. U.S. EPA Grant. #R806659010, 1979.
5. Kornel, A., Rogers, C. J. PCB Destruction: A Novel Dehalogenation. J.
Hazardous Materials. 12 (1986) 161-176.
6. Peterson, R. L. Method For Decontaminating Soil. Patent Number
4,574,013, March 4, 1986.
7. Brunelle, D. J. and Singleton, D. A. Cheaosphere, 12, (2), 1983, 183-196.
8. Li, and Alper H. Poly (ethylene glycol) Promote Reactions of Vinylic
Dibromides. Dehydrohalogenation and Palladium - Catalyzed Formal Oxi-
dative Homologation. J. Org. Chem. 1986, 51, 4353-4356.
9. Rogers, C. J. Chemical Treatment of PCBs in the Environment. EPA-600/
9-83-003, 197-201.
10. Peterson, R. Potassium Polyethylene Gycol Treatment of PCDD/PCDF - Con-
taminated Oil in Butte, Montana. IT Corp./Galson Research Corp., Project
#86-706, July 1986.
11. Rogers, C.J., Kornel, A. Chemical Destruction of Halogenated Aliphatic
Hydrocarbons. U.S. Patent 4,675,464, June 23, 1987.
-------
TIC of DRTR: RCQQ 1 . D
•p «, r
5. BC4
¦2.3C3
•2. BC3
¦1 . 3C3
1. BC3
"3.BC4
~t2
TIC of DRTR: RH1 Bl. D
i e
2B
»¦ "
22
¦ ¦ i"
24
25
2B
—i—
3£_
"2. 3C3
"2. BE5
-1.3C3
¦1.BC3
"3. BC 4
32
Figure 1
UPPER: Aroclor 1260 extracted from Guam soil.
LOWER: Guam soil after treatment.
-------
Figure 2
UPPER: Aroclor 1260 at 10 ppm.
LOWER: Guam soil after treatment.
-------
Figure 3
UPPER: Guam soil after treatment.
DC»vvA
LOWER: ¦CDMA PCB mixture
(left to right = tetra, penta, hexa at 10 ppm
and hepta, octa, nona end deca chlorobiphenyl at 5 ppm.)
-------
IN-SITU BIODEGRADATION OF ORGANIC POLLUTANTS
IN GROUNDWATER
Dr. C. Herbert Ward, Rice University, Houston, Texas
-------
In Situ biodegradation of Organic Pollutants in Ground Water
C. H. Ward
National Center for Ground Water Research
Department of Environmental Science and Engineering
Rice University, Houston, TX 7 7251
Ground waters associated with hazardous wastes and wood preservation
sites are often contaminated with the same chemicals found in surface soils.
Depending on the hydrogeological characteristics of the site, in situ
biorestoration technology may be applicable for remediation. In situ
biorestoration involves stimulation of the indigenous microorganisms with
limiting nutrients and oxygen to aerobically degrade both soluble and
nonaqueous phase organic contaminants. In situ procedures will be illustrated
with field experiments.
096Ow
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1
Subsurface Bioremediation of Creosote Contaminated Sites
J. M. Thomas and C. H. Ward
National Center for Ground Water Research
Department of Environmental Science and Engineering
Rice University, Houston, TX 77751
Introduction
Remediation of contaminated subsurface materials by instill biorestoration involves
stimulation of the indigenous subsurface microflora to degrade the oontaminants (Thomas et al.,
1987). The microorganisms are stimulated by the injection of inorganic nutrients and an
appropriate electron acceptor into the subsurface. The process is generally used to remediate the
dissoh/ed (oontaminant plume) and sorbed (bound to subsurface materials by physical/chemical
mechanisms) phases of oontaminants such as liquid fuels and creosote, rather than the
concentrated source of the contamination. In addition, the more homogeneous the contamination,
the more amenable It is to treatment. The inherent problem in treating contaminant mixtures is
ensuring the biodegradation of all the contaminants.
The majority of subsurface materials which have been remediated byjnsilu biorestoration
have been contaminated with liquid petroleum fuels. However, oontaminants associated with wood
preservation are known to be biodegradable. Compounds other than liquid fuels which have been
treated iQSllU include mineral oil hydrocarbons, waste solvents, and alkanes (Thomas et al.,
1987) Compounds such as methylene chloride, n-butandl, dimethylanillne, acetone, ethylene
glyool, teopropanol, tetrahydrofuran, and chloroform have been treated by withdrawal and
treatment above ground, followed by recharge of the reactant mixture which has been amended
with nutrients and oxygen.
Inoculation ol the subsurface with microorganisms to enhance biodegradation Is an
undemonstrated technique, although the addition ol -magic bugs" has been an Intergal part of
-------
2
many remedial programs. Basically, the role of added microorganisms in such in situ
biorestoration schemes has never been distinguished from that of the indigenous microflora. In
order for the added microorganisms to be effective, they must be transported to the zone of
contamination, colonize the subsurface solids, and grow (Thomas et al., 1987). The rate and
extent of microbial transport will depend on the characteristics of the aquifer and bacteria. The
most important aquifer characteristic which will affect microbial transport is permeability.
Cells which are bigger than the average pore size of the matrix will not be transported. In
addition, the cells may be removed from the injection fluid by sorption to clay and organic
matter or by the formation of aggregates which are too big to pass through the pore spaces.
Provided that the microorganisms are transported, the cells must colonize the subsurface
matrix and become established as part of the subsurface ecosystem. In addition, the introduced
cells must retain their special metabolic capabilities for degrading the contaminants and
compete with the indigenous microflora for nutrients, which may become limiting during the
biorestoration process.
There are basically five steps in the insim biorestoration process: 1) determining the
presence of contaminant-degrading microorganisms, 2) conducting a thorough site
investigation, 3) recovering free product, when applicable, 4) conducting laboratory studies to
determine the nutrient requirements of the indigenous microflora and the compatibility of the
nutrients with the subsurface material, and 5) designing and implementing the system.
Determining the presence of contaminant-denrariinn micronrnantenr^
In general, subsurface microorganisms are present, metabolically active, and can degrade a
variety of chemicals of environmental concern (Thomas et al., 1987). Compounds such as
acetone, ethanol, isopropanol, tert-butanol, methanol, benzene* and many alkylbenzenes,
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3
chlorinated benzenes, chlorinated phenols, and polycyclic aromatics have been shown to
biodegrade in samples of subsurface material. Ring compounds more complex than pyrene
frequently found in creosote are very difficult to degrade microbiobgically (Heitkamp et al.,
1988a; Heitkamp et al, 1988b).
Although microorganisms have been detected in many samples of subsurface materials
(Beeman and Suflita, 1987; Federte et at., 1986; Ghiorse and Balkwill, 1983; Webster et al.,
1985; Wilson and McNabb, 1983) it can not be assumed that they are ubiquitous. Analysis of
some samples has indicated minimal or no microbial activity. Ground water collected from one
contaminated site contained less than 10 cells/ml and the microflora in these samples did not
respond to the addition of oxygen and nutrients (Brubaker and Crockett, 1986). Other instances
of little or no microbial activity in the subsurface have been reported. The glucose amendment in
unsaturated material from a creosote waste pit was not mineralized whereas the glucose in
saturated material from the same borehole, and in less contaminated and pristine unsaturated
and saturated materials from the same site, was mineralized (Lee, 1986). The inhibition was
thought to be the result of high concentrations of creosote sludge in the unsaturated zone in the
waste pit.
On the other hand, microorganisms may be present in the subsurface but unable to degrade
the contaminants. For instance, a glucose amendment was mineralized in subsurface material
from both clean and contaminated areas at a site contaminated with aviation fuel; however,
biodegradation of benzene and toluene, compounds found at high concentrations in aviation fuel,
was observed in samples from the contaminated area only (Lee, 1986). Biodegradation of
benzene and toluene in the contaminated but not the unoontaminated samples suggests that a
period of adaptation, or exposure of the microorganisms to the contaminants, may be required
before significant biodegradation will occur. Adaptation may result from an increase in the
population of contaminant degraders, a mutation which codes for new metabolic capabilities,
-------
4
induction or derepression of enzymes responsible for degradation of specific contaminants
(Aelion et at.. 1987), or may be related to the concentration of the contaminant of interest, and
nutrients (Swindoll et al., 1988).
Provided that contaminant-degrading microorganims are present and metabolicaliy active in
the subsurface, the major factor limiting biodegradation in the subsurface is an adequate supply
of nutrients and an electron acceptor (generally oxygen; nitrate has been used on a limited
basis). As a result of the highly carbonaceous nature of most contaminants, any natural
biodegradation which occurs after a spill will quickly exhaust the ambient levels of nitrogen,
phosphorus, and electron acceptors. Further biodegradation will depend on the rate of recharge
of electron acceptors from mixing at the edge of the plume (Wilson et al., 1985) and the
turnover of nitrogen, phosphorus, and trace elements required for microbial metabolism.
Additions of oxygen and inorganic nutrients to laboratory samples and in the field have been
shown to increase the rate of biodegradation of many ground water contaminants (Lee and Ward,
1984; Raymond et al., 1986; Swindoll et al., 1988).
The presence of contaminant-degrading microorganisms in the subsurface is determined in
laboratory studies. Samples of core material are collected and used to determine the
biodegradation potential of selected contaminants in biotransformation and/or mineralization
experiments. Biotransformation experiments are conducted by adding contaminated core
material to incubation vessels and measuring the disappearance (biotransformation) of the
contaminants using gas chromatography. Mineralization experiments are conducted by adding
contaminated core material to incubation vessels, amending the contents with a 14C-labeled
contaminant of interest, and measuring the amount of 14C02 evolved (mineralization) from the
labeled compound using liquid scintillation counting. There are pros and cons for both methods.
In general, biotransformation experiments may be better predictors of biodegradation potential
than mineralization experiments because the oompound may be converted into cell mass and/or
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5
other products, and not evolved initially as COg- Experiments which measure mineralization
would not indicate the oonversion of the compound into products other than COg-
Biotransformation experiments can be used to determine the fate of several compounds
simultaneously, provided that the contaminants of interest are physically and chemically
similar, and extracted and chromatographed using the same methods. However, diverse
contaminant mixtures may require extensive analytical workups which are time-consuming and
costly. In addition, the disappearance of the parent compound measured by gas chromatography
simply indicates that the parent compound has been altered, and is not a good indicator of
whether or not the contaminant has been metabolized to a less hazardous or innocuous compound.
To determine the presence of potentially hazardous intermediates or products in biodegradation
pathways, the gas chromatography analysis should be coupled with mass spectrometry. A gas
chromatography-mass spectrometry workup on a mixture of compounds will be expensive.
Mineralization experiments provide direct and positive proof of the ultimate destruction of
the contaminant in a single analysis: the conversion of the compound to COg. Mineralization
experiments can be expensive to conduct because of the cost of the ^C-labeled material and
equipment required for scintillation counting. However, mineralization experiments may be
cheaper than an extensive gas chromatography-mass spectrometry workup for a contaminant
mixture. In contrast to biotransformation experiments in which several structurally similar
contaminants can be investigated simultaneously, mineralization of only one oompound at a time
can be determined. However, mineralization is advantageous because the high sensitivity of the
assay and the time required for analysis is short.
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6
Site investigation
The subsurface formation must be permeable enough to allow the transport of an electron
acceptor, usually oxygen, and inorganic nutrients to the microflora in the zone of contamination.
The rate and extent of transport of the nutrient solution will depend on the hydraulic
conductivity (K) of the formation under investigation. Formations with K values of 10"4
cm/sec or greater are usually considered good candidates for in silil biorestoration (Thomas et
al., 1987). Therefore, the first step in the feasibllty study of an affected area is to determine
the K value at the site. The K value, expressed in distance per time, indicates the rate at which a
fluid moves through a medium, and is a function of the fluid and the type of medium. The
hydraulic conductivity, which in the past has been referred to as the permeability, can be
determined using a variety of methods which include 1) slug tests, 2) pump tests, 3) variable
head tests, and 4) tracer tests. The type of test used depends on the formation and the amount of
money available to conduct the test. The geology at the site can be determined from U. S.
Geological Survey maps or from other sources available on the geology of the site. The
composition of the aquifer must be determined before a method for obtaining the K value is
chosen. The slug test is used in relatively nonpermeable formations whereas the variable head,
pump tests and tracer tests can be used in basically any formation. Whereas the slug and
variable head tests are cheap to conduct, the pump and tracer tests are more expensive.
However, the pump and tracer tests provide information over a large volume of the aquifer
while the slug and variable head tests provide measurements within a short radius of the well.
Knowledge of the K values at multiple locations is desirable because of the spacial
heterogeneity of the subsurface (Thomas et al., 1987). In addition to longitudinal
heterogeneities, vertical variabilty in K also needs to be considered to accurately predict
spreading (dispersion) of contaminants and nutrients (Moltz et al., 1986). Verticle variability
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7
can be accounted for by determining K values using multi-level sampling wells. Tracer tests
have been developed which measure vertically variable K values. Knowledge of aquifer
heterogeneities is important because transport of nutrients and the electron acceptor into zones
of low permeabilty can be limited or prevented. Partial transport of the nutrient solution into
low permeabilty zones could result in incomplete remediation.
Other aquifer characteristics that will be important in implementing iasilu biorestoration
will be the direction and rate of ground water flow, depth to the water table and zone of
contamination, and the specific yield of the aquifer. In addition, the dynamic characteristics of
the aquifer, such as hydraulic connections to other aquifers, recharge and discharge, and water
table fluctuations should be considered.
Recovery of Free Product
When applicable, as in the case of a liquid fuel spill or liquid creosote deposits, free product
should be removed before installation of an j& silu biorestoration system. Implementation of the
bioremediation system before free product recovery would be wasteful because of the enormous
quantities of nutrients which would be required to biodegrade the contaminants (Hurfburt,
1987). In addition, the high concentrations of the contaminants may be toxic to the subsurface
microflora. The amount of product that can be recovered will depend on the characteristics of the
formation. Highly permeable formations with little associated organic carbon should yield the
highest recoveries. Free product can be recovered using a variety of well systems, ali of which
take advantage of the fact that hydrocarbons are relatively insoluble in and less dense than
water. Basically, the hydrocarbons float in a cone of depression which is created by pumping at
a lower depth (Knox et a!., 1986). Materials heavior than water such as creosote are more
difficult to recover since they tend to sink to the bottom of the solurated zone.
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8
Nutrient Requirements and Compatibility
Contamination of the subsurface with highly carbonaceous wastes results in ratios of carbon
to nitrogen, phosphorus, and trace elements which are too wide to allow significant microbial
metabolism. In addition, the concentration of dissolved oxygen, the preferred electron aoceptor
in biodegradation of most contaminants, is usually too low. Laboratory experiments should be
conducted to determine the inorganic nutrient requirements of the subsurface microflora. These
tests should be conducted using samples of subsurface solids rather than the ground water.
Studies have indicated that the microflora in well water may not be representative of that
associated with subsurface solids (Thomas et al., 1987). In addition, an analysis of the ground
water for inorganic nutrients will not provide information concerning the nutrient
requirements for microbial metabolism (Raymond et al., 1978). The nutrient requirements can
be determined by incubating contaminated subsurface material with different combinations of
inorganic nutrients.
Even in the presence of sufficient inorganic nutrients, biodegradation will be limited without
sufficient levels of an electron acceptor. The preferred electron acceptor tor the majority of
contaminants will be oxygen. Although many petroleum-derived compounds can be biodegraded
anaerobically, the rates are faster under aerobic conditions. The rate-limiting step in aerobic
biodegradation of the contaminants will be the rate of transfer of oxygen to the microorganisms.
Optimum biodegradation would therefore be achieved by transporting high concentrations of
dissolved oxygen to the subsurface microflora as fast as possible.
Oxygen can be added to the subsurface by air sparging, as pure oxygen, or as hydrogen
peroxide (H202). Depending on the temperature of the ground water, air sparging and the
addition of pure oxygen can achieve dissolved oxygen concentrations of about 9 and 40 mg/L,
respectively. Hydrogen peroxide, which is completely miscible in water, can achieve much
higher concentrations of dissolved oxygen. However, H202 can be toxic to microorganisms at
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9
concentrations as low as 200 ppm. Before addition of H2O2 to the subsurface, laboratory
experiments should be conducted to determine the tolerance level of the subsurface microflora to
the peroxide. In the field, the initial concentration of H2O2 injected is usually tow
(1 ppm), and then increased gradually to concentrations as high as 500 ppm. Between step
increases in peroxide concentration, microbial numbers in ground water should be monitored to
assess potential toxic effects.
Although oxygen is the accepted electron acceptor for hydrocarbon biodegradation, the use of
nitrate has been investigated. Remediation of one gasoline spill was accomplished by adding
nitrate to aerated water, which was then injected into an aquifer to treat a hydrocarbon spill
(Batterman, 1983). The nitrate was added to serve as an electron acceptor after the oxygen
was depleted. Of the 22.5 tons of hydrocarbon retained in the subsurface, approximately 7.5
tons was removed within 120 days. Nitrate was added to an experimental field plot in Ontario,
Canada, which was artificially contaminated with a gasoline plume (Berry-Spark and Barker,
1987). Data obtained from an extensive monitoring system at the site indicated that degradation
of toluene, ethylbenzene, and m-xylene was greater in the nitrate-amended plume than in a
control plume which did not receive nitrate.
After the inorganic nutrient requirements of the subsurface microflora are determined,
experiments must be conducted to determine the compatibility of these nutrients with the
subsurface material. Analyses of both the ground water and subsurface materials are required to
determine the potential for precipitation and/or complexation of added nutrients with reactive
components in the formation. In formations with high levels of ferrous iron (Fe+2), the
addition of oxygen can precipitate the iron out of solution as ferric iron (Fe+®), which can plug
the formation. In addition to decreases in permeability, the formation of iron oxide consumes
oxygen and renders it unavailable for microbial metabolism. Hydrogen peroxide may also be
consumed by reactive materials in the subsurface and rendered unavailable. The dissociation of
-------
H2O2 may be affected by reactive species in the subsurface material (Raymond et al., 1986).
Catalysts of peroxide decomposition which may be present in subsurface materials include iron,
copper, manganese, and chromium. Rapid dissociation may form oxygen bubbles which plug the
formation. To control the rate of decomposition, orthophosphate salts may be added to complex
the catalysts. In contrast, H202 may not decompose fast enough in sand and gravel aquifers with
low organic carbon and no natural catalysts. Catalytic metals, ususally chelated, or enzymes
such as the oxidases and peroxidase, may be added to enhance H2O2 decomposition. Depending
the results of these nutrient compatibility experiments, the concentrations of the electron
acceptor and/or nutrients should be adjusted accordingly or the injection solution amended to
prevent nutrient precipitation and/or decomposition problems.
System Design and Implementation
After the laboratory experiments and site investigation have been completed, the system for
injection of the electron acceptor and inorganic nutrients is implemented. The type of well
system used will depend on the characteristics of the site under investigation. Basically, the
oxygen source and inorganic nutrients are injected into the subsurface through injection wells
or infiltration galleries while recovery wells are pumped (Figures 1 and 2). Infiltration
galleries allow infiltration of the injection solution through the unsaturated as well as the
saturated zone. Some operational designs are closed loop in which the water is recycled, thus
recycling any unused nutrients and avoiding disposal of potentially hazardous ground water. The
inorganic nutrients are usually added first, followed by the oxygen source. Simultaneous addition
of the two may cause microbial growth close to the point of injection and consequent plugging of
the aquifer. The inorganic nutrients may be added in batch or continuously. Continuous addition
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11
of the oxygen source may be advantageous because low dissolved oxygen levels are likely to be the
rate-limiting step in hydrocarbon degradation. Heterogeneities in the aquifer, such as
impermeable lenses and variable hydraulic conductivities, will hinder the distribution of
nutrients and oxygen. Once the system is operating, careful monitoring of hydrocarbon
concentrations, dissolved oxygen and nutrient levels, and microbial numbers is necessary.
Mathematical models can be used to design the injection and production system and predict
the progress of the bioremediation (Thomas et al., 1987). Models which predict bioremedial
progress require 1) a rate coefficient for biodegradation 2) a term which describes the abiotic
processes which affect contaminant and nutrient transport, and 3) a procedure which combines
the effect of the biotic and abiotic processes and simulates the remedial progress. The injection
and production system can be designed by modeling the site-specific hydraulic parameters. Most
models which are developed to describe contaminant transport and fate in ground water are based
on the advection-dispersion equation which describes the control of oontaminant transport by
ground water flow (advection) and contaminant spreading (dispersion). Models have been
developed that predict transport and biodegradation of contaminants in the saturated zone under
oxygen-limited conditions. BIOPLUME and BIOPLUME II are models which have been developed to
predict transport and biodegradation of ground water contaminants (Borden and Bedient, 1986;
Borden et al., 1986; Rifai et al., 1988).
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12
Literature Cited
Aelion, C. M., C. M. Swindoll, and P. K. Pfaender. 1987. Adaptation to and biodegradation of
xenobiotic compounds by microbial communities from a pristine aquifer. Appl. Environ.
Microbiol. 53:2212-2217.
Batterman, G. 1983. A large-scale experiment of in situ biodegradation of hydrocarbons in the
subsurface. In: Groundwater in Water Resources Planning. Volume II, Proceedings Intemat.
Symp., IASA Publication 142, Koblenz, Federal Republic of Germany, August, 1983,
International Association of Hydrological Sciences, 983-991,1983.
Beeman, R. E. and J. M. Suflita. 1987. Microbial ecology of a shallow unconfined ground water
aquifer polluted by municipal landfill leachate. Microb. Ecol. 14:39-54.
Berry-Spark, K. and J. F. Barker. 1987. Nitrate remediation of gasoline contaminated ground
waters: results of a controlled field experiment, Proceedings, NWWA/API Conference on
Petroleum Hydrocarbons and Organic Chemicals in Ground Water: Prevention, Detection and
Restoration, Nov. 17-19,1987, Houston, TX, National Water Well Association, Dublin, OH,
pp. 127-144.
Borden, R. C. and P. B. Bedient. 1986. Transport of dissolved hydrocarbons influenced by
oxygen-limited biodegrdation. 1. theoretical development. Water Resour. Res.
22:1973-1982.
Borden, R. C., P. B. Bedient, M. D. Lee, C. H. Ward, and J. T. Wilson. 1986. Transport of
dissolved hydrocarbons influenced by oxygen-limited biodegrdation. 2. field application.
Water Resour. Res. 22:1983-1990.
Brubaker, G. R. and E. L Crockett. 1986. In situ aquifer remediation using enhanced
bioredamation. In: Proceedings HAZMAT 86, Atlantic City, NJ.
Federle, T. W., D. C. Dobbins, J. R. Thornton-Manning, and D. D. Jones. 1986. Microbial
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13
biomass, activity, and community structure in subsurface soils. Ground Water 24:365-374.
Fogel, M. M., A. R. Taddeo, and S. Fogel. 1986. Biodegradation of chlorinated ethenes by a
methane-utilizing mixed culture. Appl. Environ. Microbiol. 51:720-724.
Ghiorse, W. C. and D. L Balkwill. 1983. Enumeration and morphological characterization of
bacteria indigenous to subsurface environments. Dev. Ind. Microbiol. 24:213-224.
Heitkamp, M. A., W. Franklin, and c. E. Cerniglia. 1988a. Microbial metahalim of polycyclic
aromatic hydrocarbons: Isolation and characterization of a pyrene-degrading bacterium. App.
Environ. Microbiol. 54:2549-2555.
Heitkamp, M.A., J. P. Freeman, D. W. Miller, and C. E. Cerniglia. 1988b. Pyrene degradation
by a Mycobacteria sp. Identification of ring oxidation and ring fission products. App.
Environ.Microbial. 54:2556-2565.
Hurlburt, S. 1987. Raymond approaches hydrocarbon spills head-on. Ground Water Monitoring
Review (Spring) pp. 90-93.
Knox, R. C., L. W. Canter, D. F. Kincannon, E. L. Stover, and C. H. Ward. 1986. Aquifer
restoration: state of the art. Noyes Publications, Park Ridge, NJ. 750 pp.
Lee, M. D. 1986. Biodegradation of Organic Contaminants in the Subsurface of Hazardous Waste
Sites. Ph. D. Thesis, Rice University, Houston, TX, 121 pp.
Lee, M. D. and C. H. Ward. 1984. Microbial ecology of a hazardous waste disposal site:
enhancement of biodegradation. In: Proceedings, Second International Conference on Ground
Water Quality Research, Tulsa, OK, March, OSU Printing Services, Stillwater, OK, pp.
25-27.
Moltz, F. J., 0. Guven, J. G. Melville, and J. F. Keely. 1986. Performance and analysis of aquifer
tracer tests with implications for contaminant transport modeling. EPA/600/S2-86/062, U.
S. Environmental Protection Agency, Ada, OK.
Raymond, R. L, R. A. Brown, R. D. Norris, and E. T. O'Neill. 1986. Stimulation of biooxidation
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14
processes in subterranean formations. U. S. Patent 4,588,506, May 12,1986.
Raymond, R. L, V. W. Jamison, and J. O. Hudson. 1976. Beneficial stimulation of bacterial
activity in groundwaters containing petroleum products. AlChE Symposium Series
73:390-404.
Raymond, R. L, V. W. Jamison, J. O. Hudson, R. E. Mitchell, and V. E. Farmer. 1978. Final
Report. Field application of subsurface biodegradation of gasoline in a sand formation.
Americam Petroleum Institute Project No. 307-77, Washington, DC. 137 pp.
Rifai, H., P. B. Bedient, J. T. Wilson, K. M. Miller, and J. M. Armstrong. 1988. Biodegradation
modeling at an aviation fuel spill site. ASCE (submitted).
Swindoll, C. M., C. M. Aelion, and F. K. Pfaender. 1988. Influence of inorganic and organic
nutrients on aerobic biodegradation and on the adaptation response of subsurface microbial
communities. Appl. Environ. Microbiol. 54212-217.
Thomas, J. M., M. D. Lee, and C. H. Ward. 1987. Use of ground water in assessment of
biodegradation potential in the subsurface. Environ. Toxicol. Chem. 7:607-614.
Thomas, J. M., M. D. Lee, P. B. Bedient, R. C. Borden, L W. Canter, and C. H. Ward. 1987.
Leaking underground storage tanks: remediation with emphasis on in situ biorestoration.
EPA/600/2-87/008, R. S. Kerr Environmental Research Laboratory, Ada, OK. 144 pp.
Thomas, J. M., H. J. Marlow, R. L Raymond, and C. H. Ward. 1987. Hydrologic considerations
for in situ biorestoration. Presented at US/USSR Symposium on Fate of Pesticides and
Chemicals in the Environment, Oct. 12-16, Iowa City, IA (in review by John Wiley & Sons,
Inc., New York, NY).
Webster, J. J., G. J. Hampton, J. T. Wilson, W. C. Ghiorse, and F. R. Leach. 1985. Determination
of microbial cell numbers in subsurface samples. Ground Water 23:17-25.
Wilson, J. T. and J. F. McNabb. 1983. Biological transformation of organic pollutants. EOS
64505-507.
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15
Wilson, J. T., J. F. McNabb, J. W. Cochran, T. H. Wang, M. B. Tornson and P. B. Bedient. 1985.
Influence of microbial adaptation on the fate of organic pollutants in ground water. Environ.
Toxicol. Chem. 4:721-726.
Wilson, J. T. and B. H. Wilson. 1985. Biotransformation of trichloroethylene in soil. Appl.
Environ. Microbiol. 49:242-243.
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{
-XJ-
TO SEWER OR
RECIRCULATE
PRODUCTION WELL
SsXJhrf
AIR
COMPRESSOR
NUTRIENT
ADDITION
ANK
COARSE
SAND
WATER TABLE
1
SPILLED MATERIALS
CLAY
-CXh
WATER SUPPLY
-INJECTION WELL
jj. SPARGER
FIGURE I. Typical schematic for aerobic subsurface biorestoration.
(after Raymond et_al., 1978)
Air
Cevnpftiitr or Nulrlim Addition
Hydrogen Pcroild*
FIGURE 2. Use of infiltration gallery for recirculation of water and nutrients
in in siiu biorestoration.
-------
ONSITE BIOREMEDIATION OF WOOD PRESERVING
CONTAMINANTS IN SOILS
Dr. Ronald C. Sims, EPA-RSKERL, Ada, Oklahoma
(Utah State University)
-------
ONSITE BIOREMEDIATION
OF WOOD PRESERVING CONTAMINANTS
IN SOILS
Dr. Ronald C. Sims
EPA-RSKERL, Ada, OK
(Utah State University, Division of Environmental Engineering)
Abstract
Bioremediation of soils at wood preserving sites involves the use of
naturally occurring microorganisms to destroy specific chemicals, usually
pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAH), associated
with the soil at the site. Several wood preserving locations on the Superfund List
of NPL sites have been identified for possible bioremediation. Types of biological
treatment systems currently considered for remediation of contaminated soils at
wood preserving sites include: (1) Land Treatment as defined in the Resource
Conservation and Recovery Act (RCRA), (2) In Situ Treatment, and (3) Bioreactor
Treatment. This paper addresses the goals of onsite bioremediation of soils and
current treatment systems for using bioremediation at wood preserving sites,
summarizes the status of selected sites currently considering or using
bioremediation, and identifies important questions concerning bioremediation that
should be part of any evaluation strategy when considering the potential
application of bioremediation for wood preservative contaminated soils.
Introduction
The Superfund Amendments and Reauthorization Act of 1986 (SARA)
produced major changes in the original Superfund law, including strongly favoring
permanent remedies which implement risk reduction (control) technologies that
mitigate or eliminate risks at Superfund sites. SARA established requirements for
the development and use of cost-effective treatment technologies, in accordance
with the requirements of the National Contingency Plan (NCP), that offer
permanent protection of human health and the environment. The use of naturally
occurring microorganisms to accomplish destruction and detoxification of
hazardous constituents for the protection of health and the environment is
consistent with the philosophical thrust of SARA and is the goal of onsite
bioremediation of wood preserving contaminated soils (Figure 1).
Bioremediation of soils at wood preserving sites involves the use of
naturally occurring microorganisms to destroy specific chemicals, usually
pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAH), associated
with the soil at the site. The subject of bioremediation of contaminated soils,
including applications and limitation of the technology, has been addressed at
1
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PROTECTION OF PUBLIC HEALTH AND ENVIRONMENT
TREATMENT OF WASTE CONSTITUENTS TO AN ACCEPTABLE LEVEL
\
GROUNDWATER
SURFACE WATER
ATMOSPHERE
\
i 1
I SOIL SYSTEM I
I L_
DEGRADATION
TRANSFORMATION
IMMOBILIZATION
/
Figure 1. The Goals of Onsite Bioremediation of Contaminted Soils.
2
-------
several recent scientific meetings and conferences (1,2,3,4). Three aspects that are
important for considering in order to accomplish bioremediation of contaminated
soils include: (1) waste and site characterization, (2) microbial activity and
growth of soil microorganisms, and (3) treatment system design and management.
Wood preserving waste characterization, including physical and chemical
properties and specific chemical constituents, have been addressed by Dr.
McGinnis at this Forum and by others (5,6), and therefore is not addressed in
detail in this paper. Factors affecting activity and growth of aerobic heterotrophic
microorganisms in soil involved in hydrocarbon and chlorinated hydrocarbon
biodegradation have been addressed in detail in other publications (5,6,7) and are
only considered in this paper where specific applications are discussed. This
paper addresses treatment systems that are currently being used and that are
designed based on knowledge of waste characteristics, microbial ecology, and soil
processes.
Treatfnent Systems
Three categories of treatment systems currently considered for
bioremediation of soils contaminated with wood preserving wastes include: (1)
Prepared bed systems, i.e. land treatment as characterized in the Resource
Conservation and Recovery Act (RCRA), (2) In-Situ systems, and (3) Bioreactor
systems. Information requirements applicable for all of these treatment systems
include: (1) identification of factors influencing and limiting biodegradation, (2)
biodegradation rate evaluation and stimulation, (3) extent of degradation' and
formation of intermediate products, and (4) monitoring of treatment performance
(8,9,10). The information requirements are used for each treatment system to
meet the goals of on-site bioremediation of contaminated soils illustrated in Figure
Prepared bed and land treatment systems involve the controlled application
and intimate mixing of contaminated materials into the upper zone of soil in a
prepared bed, in order to degrade and transform organic contaminants and to
immobilize inorganic contaminants, thus, leading to an environmentally acceptable
assimilation of such contaminants (9). Degradation and detoxification represent
primary mechanisms for the assimilation of the organic contaminants. Land
treatment technology is designed to accomplish simultaneous treatment and
ultimate disposal. Based upon waste and soil characteristics, specific management
techniques are frequently used to optimize the activity of naturally occurring
indigenous microorganisms to accomplishment treatment. Specific management
techniques include the incorporation of materials into the soil using mass
loadings and frequencies of application that are not inhibitory to soil microbial
processes, addition of the nutrients nitrogen and phosphorus, tilling to facilitate the
transport of oxygen through the soil, and pH adjustment. Additional management
techniques for stimulating microbial destruction of organic recalcitrant chemicals
include irrigation and the addition of easily degradable carbon substrates, for
3
-------
example, fresh manure or green vegetation.
Information concerning mechanisms involved in land treatment and
demonstrated results in laboratory and field scale tests provide a significant
information base concerning the applications of this biotreatment technology
(9,10,11,12,13,14,15,16,17,18). Additional information concerning the_functions
and processes operating within a land treatment unit treating hazardous Chemicals
are provided in the Permit Guidance Manual on Hazardous Waste Land Treatment
Demonstrations (9).
In situ biotreatment systems involve the controlled manipulation and
management of soil microbial processes and of soil physical and chemical
processes that affect natural soil microbial processes in order to achieve
degradation and detoxification of wood preserving organic waste constituents. In
situ treatment may be used for: (1) surficial soils generally less than three feet
below the surface of the soil, and (2) subsurface (vadose zone) soils that lie
between surficial soils and the groundwater table. In situ treatment systems are
designed to meet the goals of onsite bioremediation (Figure 1) without physically
removing or isolating the contaminated soil from the contiguous environment.
Successful application of in situ treatment requires information and understanding
of site, soil, and waste interactions. Specific waste, site and soil characteristics
that are important for determining the potential success for in situ treatment are
summarized in Tables 1 and 2, and discussed in detail elsewhere (6).
Management techniques for in situ bioremediation involve the manipulation
of influencing biological activity factors including nutrients, oxygen, moisture, and
pH (20). Addition of amendments, including microorganism inoculations, to
surficial soils generally has fewer restrictions with regard to mass transfer than
amendments applied to deeper soils. Manipulation of factors influencing microbial
activity, rather than addition of specially adapted microorganisms is preferred
because the addition of specially prepared microorganisms to soil environments
has significant current technical, ecnomic, and regulatory constraints (21,22).
Above ground bioreactors also can be used to treat contaminated soil at
wood preserving sites. Bioreactors are generally based on design fundamentals
taken from chemical and environmental engineering reactors that have been
designed to effect specific chemical and biological reactions. Therefore,
bioreactors can be categorized as: (1) suspended growth slurry reactors, (2) fixed
film reactors, (3) completely stirred tank reactors (CSTR), and (4) plug flow (PF)
reactors. Suspended growth reactors contain high concentrations of bacteria that
move with the liquid and that use the surrounding aqueous medium as a support
medium for growth, while fixed film reactors utilize inert supports for the
attachment of bacteria that treat water that "passes over" the retained bacteria (23).
Completely mixed reactors have a uniform composition throughout the reactor so
that the treated material leaving the reactor has the same composition as the
material in the reactor; plug flow reactors resemble "pipe flow" and have a
4
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gradient in the composition of treated material within the reactor from the "input"
side of the pipe to the "output" side. Bioreactors are generally built
above-ground in vessels where contaminated materials, amendment addition, and
environmental conditions can be controlled to accomplish the biological
destruction and detoxification of organic chemicals associated with contaminated
soils that would be added to the reactor as the waste material for treatment.
5
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Table 1. Site and Soil Characteristics Identified as Important in In Situ
Treatment (Reference 6)
Site location!topography and slope
Soil type and extent
Soil profile properties
boundary characteristics
depth
texture*
amount and type of coarse fragments
structure*
color
degree of mottling
bulk density*
clay content
type of clay
cation exchange capacity*
organic matter content*
pH*
Eh*
aeration status*
Hydraulic properties and conditions
soil water characteristic curve
field capacity/permanent wilting point
water holding capacity*
permeability* (under saturated and a range of unsaturated conditions)
infiltration rates*
depth to groundwater,* including seasonal variations
flooding frequency
runoff potential*
Geological and hydro geological factors
subsurface geological features
groundwater flow patterns and characteristics
Meteorological and climatological data
wind velocity and direction
temperature
precipitation
water budget
^Factors that may be managed to enhance soil treatment
6
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Table 2. Soil-based waste characterization (Reference 6)
Chemical class
acid
base
polar neutral
nonpolar neutral
inorganic
Soil sorption parameters
Freundlich sorption constants (K, N)
sorption based on organic carbon content (K„.)
octanol/water partition coefficient (Kow)
Soil degradation parameters
half-life (tm)
rate-constant (first order)
relative biodegradability
Chemical properties
molecular weight
melting point
specific gravity
structure
water solubility
Volatilization parameters
air/water partition coefficient (Kw)
vapor pressure
Henry's law constant (1/KJ
sorption based on organic carbon content (K^)
water solubility
Chemical reactivity
oxidation
reduction
hydrolosis
precipitation
polymerization
Soil contamination parameters
concentration in soil
depth of contamination
7
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Current Sites Using Bioremediation
Several wood preserving sites currently are being considered for application
of bioremediation technology. These sites are identified in Table 3. Table 4
contains a summary that includes the following information for each site where
information was obtained: Site name, location and EPA Region, contact person,
target clean-up levels, the organization conducting the remediation, and
information concerning the treatment systems and the status of the site
remediation.
Combinations and modifications of the treatment systems discussed above
have been used at wood preserving sites to optimize treatment and to achieve the
goals of onsite bioremediation identified previously. For example, a combination
of prepared bed land treatment and bioreactor systems is currently employed at the
Burlington Northern site in Minnesota. Because the natural soils are fine sands
with high permeability, pilot studies and the full scale implementation include a
liner (100 mil HDPE membrane) and leachate collection system (two feet wide
collection drains at 100 feet centers) to prevent possible leachate breakthrough.
Land treatment of contaminated soils was optimized based on treatability studies
using naturally occurring organisms present at the site that indicated that the
following operating and design criteria were important: (1) soil moisture should be
maintained near field capacity, (2) soil pH be maintained between 6 and 7, (3)
soil carbon:nitrogen ratios should be maintained between 25:1 and 50:1, (4)
fertilizer applications should be completed in small frequent doses, (5) waste
reapplication should occur after initial soil concentration have been effectively
degraded, and (6) waste reapplication rates of 2 to 3 pounds of benzene
extractable hydrocarbons per cubic foot of soil per three-degradation months could
be effectively degraded. Animal manure was also applied at a loading rate of two
percent of soil (dry weight basis) to provide nutrients and organic matter, which
provides organic matter to enhance retention of organic chemicals in the sandy
soils to allow biodegradation to occur. Bioremediation at this site is
approximately 50 percent complete and is presently considered a success by
personnel involved in the remediation (24).
Another combination of treatment systems is being proposed at the
Baxter/Union Pacific Tie Treating Plant site in Laramie, Wyoming. Field scale
studies involving a combination of in situ and bioreactor treatment have recently
begun. The approach involves saturating the unsaturated zone by raising the water
table, pumping solutions through the saturated area, treating the solution in above
ground reactors, followed by subsurface injection of the treated solution into the
soil. Similar to the above example, the process uses naturally occurring
microorganisms indigenous to the site. Additional information concerning specific
case histories of bioremediation of hazardous waste sites was presented by Ross et
al (25).
An important aspect of onsite bioremediation of wood preserving
8
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contaminated soil is the lack of agreement on target clean-up levels or criteria.
As indicated for the sites summarized in Table 4, target clean-up levels vary from
site to site, with some clean-up levels not determined at this time. Criteria that
are being considered in formulating target clean-up levels include risk assessment,
land ban targets, and negotiation based on site-specific constraints.
Table 3. Wood preserving sites where bioremediation has been proposed for
soil or lagoon sediments
Site Name State (Region)
Proposed Remediation
1 L.A. Clark and Sons VA (3)
2 Brown Wood Preserving FL (4)
3 Burlington Northern MN (5)
Bioremediate
Bioremediate
Landfarm
(Brainard)
4 North Cavalcade Street TX (6)
5 United Creosoting Company TX (6)
6 Baxter/Union Pacific WY (8)
7 Burlington Northern (Somers) MT (8)
8 Libby (Champion International) MT (8)
Bioremediate
In Situ remediation
Bioreclamation
Landfarm
In Situ Bioremediation
9 Koppers, Co.
10 J.H. Baxter
CA (9)
CA (9)
and Landfarm
Bioremediate
Bioremediate
9
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Table 4.
Status of wood preserving sites where bioremediation has been proposed
L.A. Clark & Sons
Spotsylvania City, VA
(Fredricksberg, VA)
Region III
Harry Harbold, U.S. EPA, (215)597-4914
Contaminants: Creosote
Media: Ground water, surface water, and soil/lagoon sediments contaminated
Decision?' Soil/lagoon sediments 3/88; ground water 1989
Remediation: Bioremediation and flush soil/lagoon sediments
Summary:
40 acre site, with contamination to water table (12 feet)
Pumpotu Sec creosote, flush *<>". foUow with siIU bioremediation
No treatability studies now - in the future
Consent decree:
Cleanup levels based on risk: 10 J ground water, with soil cleanup levels back-
"SU to^lean up site at estimated cost of $24 million
Estimated 5 years recommend an alternative method; this is a private
- S& ciS by te^mpany (Union Pacific and L.A. Clark & Sons)
Approach in Moratory treatabUity studies, followed by field study; in situ approach -
the future: nQ dig up ^d removal/transport
x/inTPr - mav be involved in EPA SITE program for biological treatment
Firms Involved: jrf sludges in the lagoon using a batch biological treatment system (in tank
treatment - bioreactor).
10
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Table 4. Continued
Brown Wood Preserving
Live Oak, FL
Region IV
John Vargo (Project Manager), U.S. EPA, (404)347-2643
Contaminants: Creosote
Media:
Soil and lagoon sediments contaminated
Record of
Decision:
4/88
Proposed
Remediation:
Bioremediation of soil
Summary:
Dismantled the facility and removed contaminated soils and sludges with "creosote"
concentrations greater than 1,000 ppm to Alabama waste disposal site (this included all
sludges); 160,000 tons of soils/sludges; site size is about 40 acres
Bioremediate residual contaminated soil with "creosote" concentration less than 1,000 ppm
using landfarming technology, about 6,000 cu. yd soil
Short-term treatability studies were conducted in laboratory columns; based on results a
field-scale engineering treatment scheme was developed based on landfarming technology:
(1) Prepare a 4-acre "treatment" site with clay liner (1 ft. to 3 ft. thick), site with 1%
grade, above ground irrigation;
(2) Will use 6-inch lifts to treat soil; anticipate needing only two 6-inch lifts to treat
the 6,000 cu. yd. soil;
(3) Target for cleanup is 100 ppm or less "creosote" which is based on risk assessment
(dermal contact); a 2-year time limit has been given for treating all contaminated
soil to 100 ppm target;
(4) After treatment is complete, site will be covered with soil and seeded;
Note: Natural microorganisms in the soil that are involved in PAH degradation will be
"concentrated" in "tanks" and sprayed on the treatment area during a "one-time"
event at the beginning of the treatment to "seed" the site with microorganisms;
microorganisms have already been identified
This is a private party cleanup; Brown foundation is paying RETEC to clean up the site;
State of Florida has been actively involved;
Bioremediation technology appears to be appropriate and successful for this site. Use of
"natural" microorganisms, i.e., no seeding with "special" organisms or "genetically
engineered" organisms, is preferred.
Firms Involved: Remediation Technology (RETEC)
11
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Table 4.
Continued
Burlington Northern (BN) (Brainard Site)
Brainard/Baxter, MN
Region V
Lonna Beilke (MPCA Project Manager), (612)296-7745
Ginny Yingling (MPCA On-Site Inspector), (621)296-7824
Amy Blumberg, U.S. EPA, (312)353-9306
Contaminants:
Media:
Remedial
Investigation/
Feasibility Study:
Proposed
Remediation:
Creosote
Ground water, soil/lagoon sediments contaminated
Completed 1984
Landfarm soil/lagoon sediments 1986; Pumpout ground water
Summary:
Ron Linkenheil (Remediation Technology) and Ginny Yingling (MPCA) - Lonna Beilke
(MPCA)
About 50% completed — field bioremediation; completed second full season
Remediation on top of original impoundment; lined impoundment site; not a clean closure
(not dig up and remove)
Contamination to depth of 25 feet
Tracking PAHs
Plan to place cap on top
95% sand site — need liner to collect possible leachate
No biological treatment of contaminated ground water - discharge to Mississippi
River (NPDES) based on comparison with paper industry
Storage pile next to pond while site remediation system was under construction
Center pivot irrigation
Source removal -
(1)
(2)
Operation:
Firms Involved:
Visual criteria - dig up soil with free oil and black color
Clean up goals - less contamination than material left behind
1,000 mg/Kg total PAH - end (negotiated)
20,000 mg/Kg total PAH - stan
Long time clean up because only use 3 acres, with repeated applications to
keep material "on site"
Remediation Technology (RETEC)
12
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Table 4. Continued
North Cavalcade Street
Houston, TX
Region VI
Louis Rogers (State Lead Site) Texas Water Commission (513) 463-8171
Contaminants: Creosote
Media:
Soil or lagoon sediments, ground water
Remedial
Investigation/
Feasibility
Study:
Complete
Record of
Decision:
Signed in 1988 and specified biological treatment as the preferred
alternative. In situ remediation is desired if feasible.
Summary:
The site is underlain by sand and clay lenses. If in situ treatment is not feasible, then "dry
phase" land treatment will be evaluated; if this approach is not chosen, slurry reactors
(above ground vessels) will be evaluated. The major concern with land treatment is the
potential for air emmissions. Control of air emissions associated with "diy phase"
treatment may be achieved; however, through use of an air inflatable dome.
The amount of contaminated soil to be bioremediated is 130,000 cubic yards. The initial
concentration of creosote was greater that 200 ppm total PAH. The target level for cleanup
of the soil is 100 ppm total PAH. The time frame for cleanup is two years (1992).
13
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Table 4. Continued
United Creosoting Company
Conroe, TX
Region VI
Louis Rogers (State Lead Site), Texas Water Commission (512) 463-8171
Contaminants: Creosote, pentachlorophenol, dioxins
Media:
Soil or lagoon sediments, ground water
Remedial
Investigation/
Feasibility
Study:
Completed
Record of
Decision:
Interim ROD signed in 1988
Summary:
Treatability studies are presently being conducted for "dry phase" land treatment. A high
density polyethylene (HDPE) liner will be used. Contaminated soil will be brought into the
lined area and managed at optimum moisture. Soil will be aerated daily. Animal manure
is added to augment biological degradation of PAH compounds. Microorganisms from the
site have been cultured and added to the contaminated soil once at the initiation of the
study. The soil will be remediated in batches on the several-acre site. No specific time
frame for cleanup has been identified.
Results to data are vey promising based on laboratory scale (one squaifc meter) plots
prepared in the field at the site. If the "dry phase" treatment is not successful, the second
alternative is to use critical phase solvent extraction.
Amount of contaminated soils is approximately 70,000 cubic yards. The target level for
cleanup of the soil is approximately 100 mg/kg total PAH, based on the recommendation of
the Center for Disease Control (CDC). This soil level is based on avoiding chronic health
impacts through ingestion.
Firms Involved: Roy F. Weston, Houston, Texas
14
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Table 4. Continued
Baxter/Union Pacific Tie Treating
Laramie, WY
Region VIII
Terry Anderson, U.S. EPA Section Chief, (303)293-1790
Felix Flechas, Project Manager, (303)293-1669
Contaminants: Creosote, some PCP
Media: Ground water, surface water, and soil/lagoon sediments contaminated
Record of
Decision: 09/86; remedial action in progress
Proposed
Remediation: Oil recovery, soil washing, bioremediation
Implemented
Remediation: Bench scale lab testing; field scale now
Summary:
Felix Flechas (EPA)
RCRA 3008H Corrective Action Site; on NPL
200-300 acre contamination associated with tie treating plant
20 feet depth contamination to bedrock - contaminated
Actions Included:
(1) Remove pond sludges;
(2) Move river;
(3) Place slurry wall 70 feet deep around site;
(4) Drain lines inside and outside of wall to maintain hydraulic gradient into
contaminated area (inside lower than outside)
Laboratory Studies; (Phase 1, short-term evaluation) ~ done
Determine potential for bioremediation using "on-site" microorganisms; enhancement studies
also conducted; mineralization of organics investigated; additional laboratory studies were
requested to provide more information
Field Scale Studies: (Phase 2, recently begun) — ongoing
In situ bioremediation: pump solution through aquifer, treat in reactor above ground,
subsurface inject into soil with organisms; isolated cells using sheet piling for hydraulic
control — raise water level for "treatment" to make unsaturated zone saturated by passage
of solution from surface through subsurface; will use site kinetics for extrapolation of time
required for concentration reduction; have not determined the target level(s) for cleanup;
waiting for RCRA numbers to be promulgated
15
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Surface bioremediation in soil in old wood preserving pond (lagoon bottom soils). Pond
bottom is clay soil that is contaminated; 20% oil in soU
Cleanup of lagoon pond bottom ~ activities ~ Land Treatment Mode
(1) Lab studies by ECOVA, Seattle, of pond bottom, land treatment mode for treatment
"in-place"; microorganism counts, PAH and PCP chemistry included in laboratory
studies
(2) Pilot studies ~ next; add manure and nutrients to pond bottom; monitor air quality
including dust which occurs with tilling operations; sprinkler irrigation on 7 plots;
maintain soils at 80% field capacity;
(3) Can use on-site soil to mix with pond bottom soil
(4) Treatment will be "layer-by-layer"; uppermost layer will be treated, then removed,
and next (top) layer will be treated, until, layer-by-layer, soil is treated down to
water table
Firms Involved: Ecova, CH2M Hill
16
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Table 4. Continued
Burlington Northern (BN)
Somers, MT
Region VIII
Stephanie Wallace, U.S. EPA, (406)449-5414
Contaminants: Creosote, metals
Media: Ground water, surface water, soil/lagoon sediments contaminated
Remedial
Investigation/
Feasibility
Study: Complete, under EPA review
Proposed
Remediation: Remove and landfarm soil/galoon sediments, removal of standing water and
sludges in 1985
Summary:
Possibility — landfarm materials at Paradise, MT, 60 miles away
Land Treatment Demonstration completed at Paradise, MT
RCRA Part B - not permitted yet; don't know if facility at Paradise will be
permitted to accept additional Somers waste
Two problems:
(1) Permit for Paradise
(2) Volumes of wastes for treatment limited by additional capacity at Paradise
waste pile and land treatment unit
(a) if 10"6 cleanup of soil (0.9 mg/Kg) is used - 75,000 cu. yd.
(b) if 10"5 cleanup of soil (9.2 mg/Kg) is used - much less soil
Distance from source area to water table - varies from 15 feet depth in one source area to
just below surface in another. Located on north shore of Flathead I afo
Paradise is a RCRA Corrective Action site; Somers will be a joint RCRA/CERCLA
Consent Decree
Land Treatment is considered good for creosote treatment since metals are not expected to
be a problem; however, air emissions may be a problem under Land Ban. Total capacity
of waste pile is 18,500 yd3.
17
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Table 4. Continued
Libby Groundwater (Champion International)
Libby, MT
Region VIII
Ken Wallace, U.S. EPA, (406)449-5414
Contaminants: Creosote, dioxin, PCP, metals, volatiles
Media:
Ground water and soil/lagoon sediments contaminated
Feasibilty
Study completed: 11/88
Record of
Decision:
09/86 - Alternate water supply
12/88 - Clean up
In situ bioremediation and land farming
Proposed
Remediation:
Summary:
Bench Scale Studies:
Soil cores studies conducted by Dr. Gary McGinnis, Mississippi State University, to
determine organic degradation rates, mobility, etc.
Land Treatment Demonstration Unit:
Approximately 7/88 to 10/88 to obtain field data on degradation rates and migration
potential. Carried out RCRA land treatment guidance.
Ground Water Biorestoration Study:
Approximately 7/87 to 9/88, to obtian field data on potential of in situ
bioremediation of upper aquifer. Oxygen injected constantly, and nutrients by
batch, in four ground water pons. Monitoring wells down gradient sampled
frequently for bacteria counts, contaminant concentrations, DO, nitrogen content,
etc.
Record of Decision: Signed December, 1988
Soils: First Step - Excavate small source areas and concentrate in large waste pit source
area. In situ initial treatment using enhanced biomass (imported bacteria, sugar, fertilizer,
product) to effect a rapid and significant reduction in creosote and PCP concentrations.
Second Step - Remove lift of treated soil from waste pit area and place in lined treatment
unit. Continue treatment until cleanup goals are achieved. = 30,000 yd'.
Upper AquifenSite wide in situ biorestoration program to be implemented. Oxygen and
nutrients will be injected at selected wells to increase natural bacterial populations in the
ground water and increase the degradation of organic compounds. Closed
injection/extraction system will be installed around the waste pit area to remove free
product from saturated zone and physically treat the highest concentration area.
18
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Lower Aquifer:Traditional product extraction methods considered ineffective for site. ROD
calls for a lab and field study of innovative clean up technologies, including in situ
biorestoration in conjuction with primary and secondary oil recovery, to assess whether
aquifer can be practicably remediated.
Clean up goals: Water - MCLs and 10s risk
Soils - Land Disposal BDAT (K001) and 10'5 risk
Firms Involved: Woodward-Clyde Consultants, MOTEC
19
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Table 4. Continued
Koppers Co., Inc., Oroville Plant
Oroville, CA
Region IX
John Kemmerer, U.S. EPA, (415)974-7112
Contaminants: Creosote, PCP, CCA
Media: Ground water, surface water, soil/onsite canal sediments, dioxin/furans
contaminated
Record of
Decision: Scheduled for September, 1989
Remedial options
under
consideration: Pump and treat ground water; wash, biroremediate, or incinerate soil/lagoon
sediments
Summary:
Fire in 1987 resulted in dioxin formation, dust problems, temporary cap on top
A landfarm treatability study was conducted while State of CA was lead; PCP leached
through soil; bioremediation options would now need liners
Firms Involved: Keystone Environmental Resources
20
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Table 4. Continued
J.H. Baxter
Weed, CA
Region IX
Carolyn Thompson, U.S. EPA, (415)974-8257
Leo Levinson, U.S. EPA, (415)974-7101
Contaminants: Creosote, PCP, metals (AS,CR)
Media: Ground water, surface water, soils/lagoon sediments contaminated
Record of
Decision: Scheduled for October, 1989
Proposed
Remediation: Bioremediate, incincerate, or fix soil/lagoon sludges
Summary:
Approximately 20 acres of contaminated soil, with depth of contamination approximately
20-30 feet;
Dr. Gary McGinnis, Mississippi Forest Products Laboratory, has conducted laboratory
treatability studies on biodegradation of creosote constituents. The effect of the metals
present in contaminated soil on biodegradation is of concern. Steel tanks have been
constructed on site that contain soil to simulate soil treatment under field conditions. The
steel tanks have been constructed to prevent migration to ground water, units began
operation on October 1, 1988.
Issues concerning this site:
(1) Cleanup targets - based on risk assessment - must be determined; use land ban
targets?
(2) Metals migration in contaminated soils, especially arsenic and chromium; fixation in
soils
Possibilities for remediation:
(1) Remove free creosote;
(2) Excavate some soil and remediate using land treatment technology;
(3) In situ treat residual soil
21
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Bioremediation Technology - Preliminary Screening Information
When considering the potential application of onsite bioremediation of
wood preserving contaminated soils, there are several issues that should be
considered as part of any preliminary evaluation. Bioremediation is often limited
by factors that include: (1) distribution of the waste limits access to the waste; (2)
supply of nutrient(s) required for metabolism; (3) toxicity of waste due to
concentration of waste constituents; (4) formation and accumulation of toxic
byproducts; (5) inadequate population(s) of requisite microorganisms; (6)
non-competitiveness or non-survivability of inoculated cultures; (7) absence of
capable microorganisms, (8) inadequate management of the system. Prior to the
application of any onsite bioremediation system for the treatment of wood
preserving contaminated soil , the factors identified above should be addressed for
each potential treatment system.
For each treatment system considered, the following information should be
obtained with regard to the site-specific application of the technology: (1) type(s)
of information needed, (2) evaluation of commercial claims, (3) potential problems
and limitations, (4) data gaps, and (5) current research focus and research results
that may be useful in designing treatability studies or in field-scale implementation
of the treatment system. The importance of conducting degradation and
detoxification treatability experiments with appropriate controls, and conducting a
site characterization to identify environmental and ecological factors that will
affect the process under field conditions cannot be overemphasized. Evaluation of
commercial claims should involve side-by-side comparisons in time using
appropriate and statistically rigorous experiments including controls that duplicate
the commercial process but exclude the commercial product.
22
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REFERENCES
1. Omenn, G.S. 1987. Environmental Biotechnology - Reducing Risks from
Environmental Chemicals through Biotechnology. Proceedings of
Conference held July 19-23 at the University of Washington, Seattle,
Washington. Plenum Press, New York. ISBN 0-306-42984-5. 505pp.
2. Engineering Foundation. 1988. Biotechnology Applied to Hazardous
Wastes. Conference held in Longboat Key, Florida, October 31-
November 4.
3. Hazardous Materials Control Research Institute (HMCRI). 01988. Use of
Genetically Altered or Adapted Organisms in the Treatment of Hazardous
Wastes. Conference held in Washington, D.C., November 30-December 2.
4. AWMA/EPA International Symposium on Hazardous Waste Treatment:
Biosystems for Pollution Control. 1988. Air and Waste Management
Association and the U.S. Environmental Protection Agency, Cincinnati,
Ohio, Feburary 20-23.
5. U.S. EPA. 1986. Waste-Soil Treatability Studies for Four Complex
Industrial Wastes. Methodologies and Results. Volumes 1 and 2.
EPA-600/6-86-003 a,b. October. EPA, Robert S. Kerr Environmental
Research Laboratory, Ada, OK.
6. Sims, R.C., J.L. Sims, D.L. Sorensen, J.E. McLean, RJ. Mahmood, and
J.J. Jurinak. 1986. Contaminated Surface Soils In-Place Treatment
Techniques. Noyes Publications, Park Ridge, New Jersey. 536pp.
7. Ghiorse, W.C. and J.T. Wilson. 1988. Microbial Ecology of the Terrestrial
Subsruface. Advances in Applied Microbiology, 33:107-172.
8. Woodward, R.E. 1988. Bioremediation Feasibility Studies for Hazardous
Waste. Pollution Engineering 20(7): 102-103.
9. U.S. EPA. 1986. Permit Guidance Manual for Hazardous Waste Land
Treatment Demonstrations. Office of Solid Waste, Washington,D.C.
EPA-530/SW-86-032. February.
10. U.S. EPA. 1988. Treatment Potential for 56 EPA Listed Hazardous
Chemicals in Soil. Robert S. Keir Environmental Research Laboratory,
Ada, OK. EPA/600/6-88-001.
11. Martin, J.P., R.C. Sims, and J.E. Matthews. 1986. Review and Evaluation
of Current Design and Management Practices for Land Treatment Units
23
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Receiving Petroleum Wastes. Hazardous Wastes and Hazardous Materials,
3(3) :261-280.
12. K.W. Brown and Associates. 1981. A Survey of Existing Hazardous
Waste Land Treatment Facilities in the United States. U.S. EPA, Contract
No. 68-03-2943.
13. Sims, R.C. 1986. Loading Rates and Frequencies for Land Treatment
Systems in- Land Treatment: A Hazardous Waste Management Alternative
(RC Loehr and J.F. Malina, Eds. Water Resources Symposium Number
Thirteen, Center for Research in Water Resources, College of Engineering,
The University of Texas at Austin.
14 Loehr, R.C., J.H. Martin, and E.F. Neuhauser. 1983. Disposal of Oily
Wastes by Land Treatment. Report to 38th Annual Purdue Industrial Waste
Conference, Purdue University, West Lafayette, Indiana, May.
15 Sims RC and M.R. Overcash. 1983. Fate of Polynuclear Aromatic
Compounds (PNAs) in Soil-Plant Systems. Residue Reviews. 88:1-68.
16 KW. Brown and L.E. Duel. 1982. An Evaluation of Subsurface
Conditions at Refinery Landfarm Sites. Prepared for the American
Petroleum Institute and the U.S. EPA, Grant No. CR-807868.
17 Mahmood, R.J., and R.C. Sims. 1986. Mobility of Organics in Land
Treatment Systems. Journal of Environmental Engineering 112(2):236-245.
18. Overcash, M.R., K.W. Brown, and G.B. Evans. 1987. Hazardous Waste
Land Treatment: A Technology and Regulatory Assessment. Prepared for
the U.S. Department of Energy by Argonne National Laboratory, September
22.
19. U.S. EPA. 1983. Hazardous Waste Land Treatment. Revised Edition.
SW-874. Office of Solid Waste and Emergency Response, U.S. EPA,
Washington, D.C.
20. Zitrides, T. 1983. Biodecontamination of Spill Sites. Pollution
Engineering. 15(11):25-27.
21. Lee, M.D., Thomas, J.M., Borden, R.C., Bedient, P.B., Wilson, J.T., and
Ward, C.H. 1988. Biorestoration of Aquifers Contaminated with Organic
Compounds. CRC Critical Reviews in Environmental Control. 18(1):
29-89.
24
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22. Goldstein, R.M., L.M. Mallory, and M. Alexander. 1985. Reasons for
Possible Failure of Inoculation to Enhance Biodegradation. Applied and
Environmental Microbiology. 50:977.
23. Nyer, E.K. 1985. Groundwater Treatment Technology. Van Nostrand
Reinhold Company, Inc. ISBN: 0-442-26706-1. 188pp.
24. Linkenheil, R.J., and T.J. Patnode. 1987. Bioremediation of Contamination
by Heavy Organics at a Wood Preserving Plant Site. Proceeding of The 8th
National Conference on Superfund, Washington, D.C. The Hazardous
Materials Control Research Institute. November 16-18.
25. Ross, D., T.P. Maziarz, and A.W. Borquin. 1988. Bioremediation of
Hazardous Waste Sites in the USA: Case Histories, pp. 395-397. In:
HMCRI's 9th National Conference and Exhibition, Superfund. The
Hazardous Materials Control Research Institue, Washington, D.C.,
November 28-30.
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EXISTING DATA ON WOOD PRESERVING WASTE INCINERATION
Donald A. Oberacker, EPA-RREL, Cincinnati, Ohio
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PRESENTATION BY DONALD A. OBERACKER - RISK REDUCTION ENGINEERING LABORATORY
PART I: EXISTING DATA ON WOOD PRESERVING WASTE INCINERATION
PART II: EXAMPLES OF MOBILE/TRANSPORTABLE HAZARDOUS WASTE
INCINERATION TECHNOLOGIES FOR FIELD SITE CLEANUP OPERATIONS
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PART I
EXISTING DATA ON WOOD PRESERVING WASTE INCINERATION
OCTOBER, 1988
BY
DONALD A. OBERACKER
TECHNICAL SUPPORT SPECIALIST
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
RISK REDUCTION ENGINEERING LABORATORY
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INTRODUCTION
The purpose of this paper is to provide a brief perspective on how incineration
might be considered a solution for the cleanup of abandoned or problem land sites where
wastes from wood preserving industries have caused pollution problems.
As an initial outlook position, this author believes that both the contaminated
soils which may include low ppm to percentage amounts of tetra- or pentachlorophenols
and other compounds such as benzene, toluene, and various polynuclear aromatics as well
as actual pockets of the waste sludges or liquids or their leachates can readily be
treated by high temperature incineration processes to result in cleaned or "sterilized"
soil residues. The cleaned material which will be in the form of dried soil/ash can then
be set back in place if desired, thus restoring the site for normal commercial or even
residential1.' purposes. Of course, some may consider the post-treated soils more as "fill
material", and this is very true since incineration will strip out all organics, leaving
the soil void of natural nutrients necessary to grow grass or pi ants and therefore a 1 aye'
of good top soil would be needed on top as a finishing step.
Procedurally, one would probably only consider incineration for cases where relative
open fields or easily accessable or excavatable soil and/or contaminated groundwaters are
involved. Obviously, soils underneath substantial buildings which are inaccessable would
not be considered for incineration.
In addition, an initial study must be made to determine whether the excavated materia
would be best treated on site by a mobile or transportable incinerator brought to the si't4
or if the soil should be hauled to a fixed or stationary commercial incinerator fac ility.
For the purposes of this presentation at least, it will be assumed that hauling to a dis-
tant stationary incinerator is not feasible, due to economics or availability considerate
AVAILABLE PERFORMANCE DATA
The first four overheads or figures show the summary results of four specific
incineration tests that EPA has performed on tfcie types of chemical contaminants in
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treated wood, or wastes from the wood treating industry. It should be noted that this
presentation covers only the creosote or tetra-pentachlorophenol types of wood preser-
vatives and does not cover the newer metal types of materials.
Figures 1, 2, and 3 show the overaii characteristics of the wastes incinerated
and the performance results which generally demonstrate the effectiveness of incineration.
Figures 1-3 are considered "pilot-scale" operations, while figure 4 reports on a field-
scale operation. All of these tests were made on relatively small fixed incinerators,
however it would be expected that larger units or mobile and transportable units would
be able to accomplish similar results since the primary need is for adequate handling,
combustion temperatures, and residence times, etc. Figure 4 stands out as an exception
in terms of performance, however, showing that some amounts of dioxins and furans can
be emitted from the incinerator stack. It is believed that this condition of incompletely
destroyed pollutants was the result of the lower (below 1800F) temperature conditions that
were prevelant in this particular incinerator. Operating this unit at conditions closer
to that which EPA used in its pilot tests most likely would have resulted in much cleaner,
probably undetectable levels of these pollutants.
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CONCLUSIONS
In conclusion, while there is only a limited amount of data on file as shown
to indicate the incinerability of wood preserving wastes of the organic type, this
author believes that there is sufficient grounds to seriously consider incineration as
a treatment method for such sites. The chemical compounds themselves, being more
easily destroyed than other commonly incinerated compounds such as carbon tetrachloride,
PCBs, and chlorobenzenes, etc., are considered by many to be "easily incinerated".
Nevertheless, any plan or activity which incorporates incineration at any specific
site should probably include, as a beginning, test or trial burns of the specific waste
and incinerator combination up front to prove its viability.
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Figure 1
INCINERATION TRIAL BURN BY EPA's INDUSTRIAL ENVIRONMENTAL
RESEARCH LABORATORY (IERL), CINCINNATI - 1983
TEST FACILITY:
WASTE DESCRIPTION:
WASTE ANALYSIS:
RESULTS:
WASTE FEED RATES:
LOS ALAMOS NATIONAL LABORATORY, (DOD) CONTROLLED
AIR INCINERATOR BY ENVIRONMENTAL CONTROL PRODUCTS,
MODEL 500-T (NOMINAL 500 LBS./HR.), WITH MINOR
MODIFICATIONS TO FACTORY UNIT.
KOREAN WAR-VINTAGE ARMY AMMUNITION BOXES TREATED
WITH PENTACHOROPHENOL (PCP), CRUSHEH
CHLORINE CONTENT - 0.07 PERCENT RY WEIGHT
PCP CONTENT - 0.103 to 0.106 PERCENT BY WEIGHT
PINE WOOD WITH 7960 (ACTUAL) AND 9066 (DRY) BTU/LB
ORE FOR PCP WAS GREATER THAN 99.99%
NO TCDD IN STACK EMISSIONS (DET. LIMIT 1 PPB)
NO TCDF IN STACK EMISSIONS (DET. LIMIT 5 PPB)
ASH - NOT SAMPLED AND ANALYZED
60 - 100 LBS./HR.
INCINERATION CONDITIONS: 1800 F FOR A GAS RESIDENCE TIME OF 1.5 SECONDS
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Figure 2
RREL DATA ON INCINERATING WOOD PRESERVING WASTES
TEST FACILITY: EPA COMBUSTION RESEARCH FACILITY ROTARY KILN
SUMNER OF 1987
WASTE DESCRIPTION: KOOl-PENTACHLOROPHENOL (PCP) TYPE
ALLIED CHEMICAL'S AMERCIAN WOOD DIVISION OF POWER
TIMBER COMPANY, RICHTON, MISSISSIPPI
BOTTOM SEDIMENT/SLUDGE FROM WASTEWATER TREATMENT
CONTAINING PCP (INCLUDING PENTA- AND TETRACHLORO-
PHENOLS, VOLATILE ORGANIC SOLVENTS, E.G. BENZENE,
TOLUENE, AND POLYNUCLEAR AROMATIC (PNA) PARTS OF
CREOSOTE)
ANALYSIS: SOIL 40%
WATER 30%
WOOD CHIPS 10%
ACTIVE ORGANICS 20%
TSUI
ASH CONTENT 12-51%
HEATING VALUE 3800-R300 BTU/LB.
PCP 970-3800 PPM
RESULTS: NON-DETECTABLE FOR ALL PRIORITY RCRA VOLATILE AND
SEMI-VOLATILE COMPOUNDS IN ASH AND IN SCRUBBER
WATER (INCLUDING DI0X1NS/FURANS)
STACK TESTING RESULTS NOT AVAILABLE AT THIS TIME
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Figure 3
RREL DATA ON INCINERATIN WOOD PRESERVING WASTES (CONTINUED)
SUMMER OF 19R7
TEST FACILITY: JOHN ZINK COMPANY ROTARY KILN
WASTE DESCRIPTION: KOOl-C (CREOSOTE TYPE)
ALLIED CHEMICAL'S BIRMINGHAM, ALABAMA PLANT, BOTTOM
SEDMIENT SLUDGE FROM TREATMENT OF WASTEWATERS
FROM PROCESSES USING CREOSOTE, THIS MATERIAL
OBTAINED FROM THE PEARL RIVER WOOD PRESERVING
CORPORATION, PICAYUNE, MISSISSIPPI
ANALYSIS:
SOIL 30%
WATER 20%
WOOD CHIPS 10%
NAPTHALENE 4%
PHENANTHRENE 3.5%
FLUORANTHENE 2.5%
OTHER ACTIVE ORGANICS 30%
'TTTCJT
RESULTS:
ASH CONTENT
HEATING VALUE
VOLATILE MATTER
12t51%
10,000-11,000 BTU/LB,
57-81%
NON-DETECTABLE FOR ALL PRIORITY RCRA VOLATILE AND
SEMI-VOLATILE COMPOUNDS IN ASH AND IN SCRUBBER
WATER (INCLUDING DIOXINS/FURANS)
STACK TESTING RESULTS NOT AVAILABLE AT THIS TIME
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Figure 4
INCINERATION DATA BY EPA's TIER 4 NATIONAL DIOXIN STUDY 1986-7
TEST FACILITY: INDUSTRIAL CONTROLED AIR INCINERATOR WITH WASTE HEAT BOILER
WASTE DESCRIPTION: PAINT FILTERS AND DRY PAINT, PAINT SLUDGE, AND WOOD/PLASTIC
SCRAP MATERIAL FROM MANUFACTURE OF PCP-TREATED WOOD/PVC PLASTIC
COATED STORM WINDOWS, WOOD FRAMING TREATED WITH 0.1 LB/FT3 PCP
RESULTS: FOR AN AVERAGE FEED RATE OF 2390 LB/HR TO THE INCINERATOR;
TOTAL PCDD EMISSIONS: 1370 MICROGRAMS/HOUR (STACK)
2,3,7,8 8.62 "
TOTAL PCDF EMISSIONS: 4600 " "
ASH ANALYSES:
TOTAL PCDD: 1 to 302.6 PPB
2,3,7,8 ND to 0.2 "
TOTAL PCDF: 0.07 to 17.7 PPB
INCINERATOR TEMPERATURES:
PRIMARY CHAMBER: 1100 to 1800 F (AVG. 1392 F)
SECONDARY CHAMBER: 940 to 1820 F (AVG. 1480 F)
FACILITY: ANDERSEN WINDOW COMPANY
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PART II
EXAMPLES OF MOBILE/TRANSPORTABLE HAZARDOUS WASTE
INCINERATION TECHNOLOGIES
FOR
FIELD SITE CLEANUP OPERATIONS
OCTOBER, 1988
BY
DONALD A. OBERACKER
TECHNICAL SUPPORT SPECIALIST
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
RISK REDUCTION ENGINEERING LABORATORY
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INTRODUCTION
In this PART II of my presentation, I have focused on the technologies or actual
available incinerator hardware in the commercial sector which could very likely be
employed in the cleanup of contaminated wood preserving waste sites. An underlying
assumption is that most or all of these sites are of a sufficiently small size or
tonnage in total to be handled by mobileior transportable incinerators situated on
the site itself. However, I do recommend that in all cases, the logistics, legality,
and economics of transporting the waste or ;contaminated soils themselves to an-'existing,
stationary incinerator (if available) be considerd.
Figures 5 through 17 presented as overhead projections are intended to carry one
common theme, namely that the mobile/transportable incinerator industry is very much
"existing and available". Virtually all of the firms involved got their concept or start
in this business by following the impetus of EPA's mobile incinerator, and/or EPA1s
engineering study which examined the design feasiblity of larger transportable units.
The figures provide the reader an idea of the relative size and in some cases the past
accomplishments of the unit in terms of cleaning up sites of various types of pollution.
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CONCLUSIONS
As the presentation indicated, there are a host of available mobile/transportable
incineration firms with a variety of hardware available on the market. This paper
makes no attempt to steer or recommend the potential user towards any one particular
firm or brand of incinerator, but rather simply presents the names and characteristics
of some of the units which are readily known. The list of manufacturers is rot necessarily
complete — that is, there may well be a few additional firms who have entered this
marketing area.
It is recommended that any particular site cleanup action should probably begin
by testing the commercial market for interest in the project as a first step, then
advancing toward normal request for proposals and bids as the project moves along.
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Figure 5
DEFINITIONS
MOBILE: LARGELY MOUNTED ON SEMI-TRAILERS AND
MEETING LEGAL OVER-THE-ROAD SPECIFICATIONS,
MINIMUM ON-SITE CONSTRUCTION
TRANSPORTABLE: MOSTLY INVOLVING FIELD ERECTION/ASSEMBLY OF
TRUCK-TRANSPORTED COMPONENTS, SIGNIFICANT
BUT TEMPORARY EQUIPMENT FOUNDATIONS, BUT
DISASSEMBLED UPON JOR COMPLETION
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Figure 6
EPA'S MOBILE INCINERATION SYSTEM WHICH INSPIRED THE
DEVELOPMENT AND GROWTH OF SIMILAR PORTABLE/TRANSPORTABLE
FIELD SITE INCINERATION SYSTEMS IN THE COMMERCIAL SECTOR
OVERALL CHARACTERISTICS:
- DEVELOPED BY ORD DURING APPROXIMATELY 1970-1982
- INITIAL PERFORMANCE TESTS AT EPA-EDISON, NEW JERSEY
ON PCRs AND RCRA WASTES
- SET UP IN REGION VII IN DECEMBER, 1984 FOR DENNY FARM
DIOXIN CONTAMINATED SOILS, DEBRIS, AND LIQUIDS
- ACCOMPLISHMENTS TO DATE:
OVER 3 MILLION POUNDS OF SOLIDS
OVER 200,000 POUNDS OF LIOUIDS
AVERAGE THROUGHPUT: 3,000 POUNDS PER HOUR
70 PERCENT ON-LINE TIME
- SYSTEM DESCRIPTION:
NOMINAL 12 MILLION BTU/HR. TOTAL
ROTARY KILN 52 IN. ID x 16 FT. LONG
AFTERBURNER 52 IN. ID x 36 FT. LONG
HOT CYCLONE PARTICLE SEPARATOR
WET ELECTROSTATIC PRECIPITATOR
AIR OR OXYGEN PLUS FUEL OIL FIRED
SHREDDER
- CURRENT STATUS:
TO BE DETERMINED
LARGER, TRANSPORTABLE CONCEPT:
EPA ORD SPONSORED INITIAL FEASIBILITY/DESIGN
STUOIES IN EARLY 1980's
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Figure 7
STATIONARY PILOT-SCALE FACILITIES FOR DIAGNOSTIC TEST-BURNS OF
SAMPLE QUANTITIES OF VARIOUS CONTAMINATED SOILS AND OTHER WASTES
EPA's COMBUSTION RESEARCH FACILITY
JEFFERSON, ARKANSAS (ORD-CINCINNATI)
- ROTARY KILN PLUS AFTERBURNER, 3 MILLION BTU/HR.
(4 FT. DIAMETER x 6 FT. LONG)
- LIQUID INJECTION UNIT PLUS AFTERBURNER,
3 MILLION BTU/HR.
- PERMITS: RCRA, PCB, DIOXIN
- SAMPLE SIZE: 4 TO 10 DRUMS MIN.
JOHN ZINK COMPANY, TULSA, OKLAHOMA
- ROTARY KILN PLUS AFTERRURNER, 3-5 MILLION BTU/HR.
(3 FT. DIAMETER x 15 FT. LONG)
- LIOUID INJECTION UNIT PLUS AFTERBURNER,
3 MILLION BTU/HR
- PERMITS: RCRA (NO PCB)
- SAMPLE SIZE: 10 TO 20 DRUMS MIN.
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Figure 8
EXAMPLES OF COMMERCIAL FIRMS ACTIVE IN FIELD SITE CLEANUP
VIA INCINERATION WITH MOBILE/TRANSPORTABLE SYSTEMS
- ENSCO CORPORATION
LITTLE ROCK AND ELDORADO, ARKANSAS
- WESTON SERVICES INCORPORATED
WEST CHESTER, PENNSYLVANIA
- INTERATIONAL TECHNOLOGY (IT) CORPORATION
KNOXVILLE, TENNESSEE
- VESTA TECHNOLOGY LTD.
FT. LAUDERDALE, FLORIDA (THERMALL, INC.)
- THERMAL INCORPORATED
PEAPACK NEW JERSEY
- WILLIAMS ENVIRONMENTAL SERVICES INCORPORATED
STONE MOUNTAIN, GEORGIA
- ROLLINS ENVIRONMENTAL SERVICES INCORPORATED
ATLANTA, GEORGIA; WILMINGTON, DELAWARE;
DEER PARK, TEXAS
- ENVIRITE FIELD SERVICES INCORPORATED
ATLANTA, GEORGIA AND PLYMOUTH MEETING,
PENNSYLVANIA
CHEMICAL WASTE MANAGEMENT INCORPORATED
CHICAGO, ILLINOIS
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Figure 9
ENSCO CORPORATION MOBILE OR TRANSPORTABLE INCINERATORS
- SIX (6) MOBILE UNITS (3 IN FINAL CONSTRUCTION)
- SMALLER UNITS ARE 5-6 TONS/HR (4 UNITS EXIST)
- LARGER UNITS ARE TRANSPORTABLE, 20 TONS/HR
(CONSTRUCTION SCHEDULED FOR COMPLETION IN
FALL, 1988)
- UNITS HAVE BEEN IN USE AT TAMPA, EL DORADO,
GULFPORT, AND SMITHPORT (CANADA)
- COMPOUNDS TREATED:
PCBs, DIOXINS, HERBICIDE ORANGE, OTHER
RCRA CHEMICALS IN CONTAMINATED SOILS
- SITE INVOLVEMENT:
TAMPA, FLORIDA
CHICAGO
EL DORADO, ARKANSAS
(SUPPLEMENTS MAIN PCB UNIT)
GULFPORT, MISSISSIPPI
TEXAS
SMITHVILLE (CANADA)
RICHMOND, VIRGINIA
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Figure 10
WESTON SERVICES, INCORPORATED TRANSPORTABLE INCINERATOR
- ROTARY KILN 7 FT. DIAMETER x 25 FT. LONG
- AFTERBURNER 8 FT. DIAMETER x 33 FT. HEIGHT
- FABRIC FILTER APCD SYSTEM
- PACKED TOWER HCL CONTROL UNIT
- DESIGN CAPACITY 6 TONS/HOUR ON CONTAMINATED
SOIL & DEBRIS
- USED AT: BEARDSTOWN, ILLINOIS (5,000-10,000 TONS)
- COMPOUNDS TREATED: PCBs (UP TO 1% OR 10,000 PPM
IN SOIL)
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Figure 11
INTERNATIONAL TECHNOLOGY (IT) TRANSPORTABLE INCINERATOR
- ONE (1) UNIT EXISTS, HAS BEEN USED IN COMPLETING THE
INCINERATION OF THE CORNHUSKER SITE (40,000 TONS Of
TNT & DINITROTOLUENE & TRINITROBEWZENE CONTAMINATED
SOILS - EXPLOSIVES)
- TWO (2) MORE UNITS UNDER CONSTRUCTION (1989) INTENDED
FOR MOTCO (TEXAS) SITE WITH PCB AND STYRENE TAR
CONTAMINATION
- ROTARY KILN IS 6-1/2 FT. DIAMETER x 45 FT. LONG,
COUNTERCURRENT
- AFTERBURNER IS VERTICAL, 1200 C
- TOTAL HEAT CAPACITY IS 56 MILLION BTU/HR (EITHER
KILN PLUS AB OR AFTERBURNER ALONE)
- SOIL THROUGHPUT CAPACITY NOMINALLY 20 TONS PER
HOUR, OVER 15 DEMONSTRATED
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Figure 12
VESTA TECHNOLOGY LTD. MOBILE INCINERATORS
(USING THERMALL TECHNOLOGY)
- TWO (2) UNITS EXIST, "VESTA 80" and "VESTA 100"
- MODEL 80 IS A 8 MILLION BTU UNIT WITH A 5.03 FT.
DIAMETER BY 16 FT. LONG KILN AND A 5.03 FT.
DIAMETER BY 20 FT. LONG AFTERBURNER
- MODEL 100 IS A 10 MILLION BTU/HR. UNIT WITH A
4.33 FT. DIAMETER BY 25 FT. LONG KILN AND A
5.33 FT. DIAMETER BY 30 FT. LONG AFTERBURNER
- CAPACITIES CLAIMED:
MODEL 80: 1000-2000 POUNDS PER HOUR OF SOILS
MODEL 100: 3000-5000 POUNDS PER HOUR OF SOILS
- SITES TREATED:
REGION I IN ASHLAND, MASSACHUSETTS, 1200-1600 TONS
OF NITROBENZENE CONTAMINATED SLUDGES, PART OF A
35 ACRE SITE WITH CONCENTRATIONS UP TO 9100 PPM,
COMPLETED
REGION IV IN ABERDEEN, NORTH CAROLINA* 5000 POUNDS
OF HAZARDOUS WASTE CONSISTING OF SOILS CONTAMINATED
WITH CARBON TETRACHLORIDE AND PESTICIDES, COMPLETED
_ FUTURE SITES:
DELRAY BEACH, FLORIDA, 3000 CU. YDS. OF PESTICIDE
CONTAMINATED SOIL
CHEHALIS, WASHINGTON, PENTACHLOROPHENOL AND DIESEL
FUEL CONTAMINATED DEBRIS
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Figure 13
THERMALL INCORPORATED
(ALSO SEPARATELY SUPPLIED VESTA'S UNITS)
- UNITS IN DESIGN PHASE:
A 4 TON/HR UNIT WITH 25 MILLION BTU/HR CAPACITY
USING A 6.5 FT. DIAMETER KILN BY 28 FT. LONG .
A 6 TON/HR UNIT WITH 35 MILLION BTU/HR CAPACITY
USING A 8 FT. DIAMETER KILN BY 35 FT. LONG
- AVAILABILITY:
4 TON/HR UNIT EXPECTED TO BE COMPLETE IN SPRING
OF 1989
6 TON/HR UNIT IN DESIGN PHASE, COMPLETION NOT
SPECIFIED
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Figure 14
ROLLINS ENVIRONMENTAL COMPANY'S ROTARY RECTOR TRANSPORTABLE SYSTEM
(FORMERLY "PEDCO/PEI FAST ROTARY REACTOR")
- 33.5 MILLION BTU/HR ROTARY KILN W/FLUIDIZED SAND
RECIRCULATING
- KILN IS 3.3 METERS (10.9 FT.) DIAMETER x 65 FT. LONG
- FORCAST CAPACITY 150 TONS/DAY OF 2500-3500 BTU/LB.
MATERIALS (CLAIMED SELF-SUSTAINED COMBUSTION AT
THAT BTU)
- FIELD-TRANSPORTABLE VERSION TO HAVE DRY SCRUBBING
(NO WATER USE)
- CURRENT UNIT UNDER TEST IN DEER PARK, TEXAS
- SMALLER, PILOT UNIT TESTED 1986 IN STATIONARY MODE,
USED A 2 FT. 4 IN. ID X 18 FT. LONG KILN/REACTOR
- DEVELOPED BY PEI OF CINCINNATI, OHIO COAL OFFICE,
AND UNIVERSITY OF CINCINNATI
- TARGET BUSINESS:
INITIAL: LARGE SAMPLE TEST BURNS AT DEER PARK
ON SUPERFUND SOILS, ETC.
LATER: TRANSPORT TO FIELD SUPERFUND SITES
- STATUS:
INSTALLED AND UNDERGOING HOT TESTING IN OCTOBER, 1988
STATIONARY TESTING WITH SOLID/LIQUID RCRA & PCB
WASTES IN FALL, 1988 (DIOXIN PERMIT POSSIBLE)
PLANS TO CONVERT TO FIELD-TRANSPORTABLE UNIT USING
DRY-SCRUBBER IN 1989
LOOKING FOR SITES TO APPLY
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Figure 15
EMVIRITE FIELD SERVICES INCORPORATED TRANSPORTABLE INCINERATOR
- LARGE ROTARY KILN PLUS AFTERBURNER, RATED AT 82 MILLION
BTU/HR WITH SOILS OF 1200 TO 2000 BTU/LB.
- SOILS THROUGHPUT CAPACITY 15 TONS/HR
- USES BAG HOUSE (FABRIC FILTER) PLUS WET SCRUBBER
- HAS INCINERATED CREOSOTE CONTAMINATED DREDGED LAGOON
SLUDGES WHICH WERE STABILIZED WITH CEMENT KILN DUST
FOR HANDLING (NO PCPs, ONLY PNAs) (THE PRENTISS,
MISSISSIPPI SITE OF 7500-9500 TONS, NOT COMPLETED)
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Figure 16
CHEMICAL WASTE MANAGEMENT'S TRANSPORTABLE ROTARY KILN:
"PY-ROX" UNIT
IN CONSTRUCTION AT SAUGET, ILLINOIS (TWI FACILITY)
50 MILLLION BTU/HR.
CONSTRUCTION STARTED: 6/BR (PERMITTED TO BUILD BY IEPA)
SCHEDULED TO OPERATE 3/89
OTHER UNITS AT:
KETTLEMAN HILLS, CALIFORNIA (PERMIT APPLIED FOR)
MODEL CITY, NEW YORK (IN PERMITTING)
MEMPHIS, TENNESSEE (PROPOSED)
ALL UNITS UTILIZE DRY SCRUBBER + FABRIC FILTER (BAG HOUSE)
CAPACITY CLAIMED: 30,000 TONS/YR.
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Figure 17
REMAINING ISSUES AND RECOMMENDATIONS
ISSUES:
PERMITTING
TYPE AMD CONCENTRATION OF ANY HEAVY TOXIC METALS
AFFORDABILITY OF INCINERATION ($200 TO $500 AND
UP PER TON NET)
PRE-PROCESSING REQUIREMENTS (SHREDDING, MATERIALS
HANDLING, SOLIDIFYING LAGOON LIQUIDS AND SOLIDS,
ETC.)
RELEASE OF POLLUTANTS DURING EXCAVATION AND
HANDLING
DELISTING AND DISPOSAL OF TREATED MATERIAL
RECOMMENDATIONS:
DESIRABILITY OF DIAGNOSTIC TEST BURNS AT PILOT SCALE
INCLUDE ALL REAL COST ITEMS (SAMPLING AND ANALYSIS,
MONITORING, SITE CLEANUP AND CLOSURE, ETC.)
CONSIDER MULTIPLE BIDDERS AND TECHNOLOGIES
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PUMP-AND-TREAT TECHNOLOGY
Dr. Joseph F. Keely, Portland, Oregon
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* * * Preliminary Outline * * *
PUMP-AND-TREAT TECHNOLOGY
by
Joseph F. Keely, Ph.D., P.Hg., FAIC/CPC
Ground-Water Quality Consultant
a presentation delivered to the
U.S. EPA FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX, San Francisco
24-25 October 1988
I. Introduction
- purpose (contaminant removal & plume isolation)
- traditional conceptual basis (how pump-and-treat works)
- state-of-the-science conceptual basis (how it doesn't work)
II. Design
- principal system components (wells, header system, etc.)
- drawdown cones vs. capture zones
- effects of partial penetration, streams, etc.
- contaminant transport data needs
III. Operation
- hydrodynamic effects, limitations (esp., velocity regions)
- chemical and biological effects, limitations
- continuous operation vs. pulsed pumping
IV. Compliance and Performance Monitoring
- hydrodynamic vs. chemical monitoring
- hydrodynamic compliance monitoring strategies
- performance evaluation strategies
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PUMP AND TREAT TECHNOLOGY
Joseph F. Keely, Ph.D., P.Hg., FAIC/CPC
Ground-Water Quality Consultant
Suite 2002, Tanasboume Mall
2700 NW 185th Avenue
Portland,Oregon 97229
presented to
FORUM ON REMEDIATION OF WOOD PRESERVING SITES
U.S. EPA Region IX
San Francisco, CA
24 October 1988
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FORUM ON REMEDIATION
OF WOOD PRESERVING SITES
PUMP AND TREAT TECHNOLOGY
by
Joseph F. Keely, Ph.D., P.Hg., FAIC/CPC
Wellfield Hydrodynamics
Pumping and injection wellfields comprise an effective method of generating substantial changes in the
direction and rate of ground-water flow. The principle involved is purely physical: lower the fluid pressure in the
aquifer locally (by pumpage) and an immediate convergence of flow lines is centered on the source of the
pressure reduction (the pumped well). Alternately, raise the fluid pressure in the aquifer locally (by injection)
and an immediate divergence of flow lines is centered on the source of the pressure increase (the injection well).
Regionally, the flow system suffers a minor, localized disturbance. Locally, the flow system yields nearly radially
to the well; not only does ground water flow to a pumping well from the [pre-operational] upgradient side of the
well, but from the [pre-operational] downgradient side also. The distance downgradient from which a pumping
well will be able to draw waters back to itself is defined as the stagnation point (Keely and Tsang, 1983).
1. Capture Zones
More precisely, the stagnation point of a angle pumping well is located at that distance downgradient where
the velocity of flow back to the well, caused by pumpage, is directly offset by the velocity of flow away from the
well caused by the natural flow system. The stagnation point is the downgradient limit of the capture zone of a
single pumping well; the lateral limits of the capture zone are found at a distance from the centerline (e.g., the
line that bisects the well along the upgradient-downgradient axis) equal to the value obtained by multiplying the
stagnation point distance by the mathematical constant pi. The capture zone is that portion of the aquifer that
contains ground water that will be eventually captured and discharged by the pumping well. It does not include
the entire zone of pressure influence (drawdown cone) generated by the pumping well, unless the natural flow
1
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system velocity is zero (Keely, 1984).
2. Rejection Zones
By reversing the frame of reference, it can be seen that a stagnation point forms upgradient of injection
wells. The push of waters out of the well in the [pre-operational] upgradient direction is directly countered by
the movement of the natural flow system in the [pre-operational] downgradient direction. The stagnation point
that forms in this circumstance is at the upgradient limit of the rejection zone. Hie lateral limits of the rejection
zone are, of course, found at a distance from the centerline equal to the value obtained by multiplying the
stagnation point distance by the mathematical constant pL The rejection zone is that portion of the aquifer
which will eventually contain only injected water (the native water in the formation is displaced first), and which
does not allow the entry of additional native waters. It does not include the entire zone of pressure influence
(injection cone) generated by the injection well, unless the natural flow system velocity is zero.
Unfortunately, most publications still do not provide adequate distinction between the capture zone and the
zone of pessure influence of a well. One of the most popular ground-water textbooks (Freeze and Cherry, 1979)
makes no mention of such a distinction, or of capture zones generally. The same is true of a highly respected
industry text (Driscoll, 1986). Todd (1980), does provides the mathematical description of a capture zone, but
does not discuss the practical ramifications of its delineation. An EPA Handbook provides some discussion of
capture zones (EPA, 1985), but it couches design recommendations primarily in terms of drawdown (water level
declines caused by pumpage). It also does not carry the idea of capture zones over into key figures (e.g., Fig.'s
5-2,5-3,5-5, and 5-6 of EPA, 1985), leaving the reader a bit unsure of the message.
3. Welt Spacing?
When there are two or more pumping wells operating in unison, and they are spaced closely enough, their
individual capture zones coalesce into a single collective capture zone. When that happens, the individual
stagnation points coalesce into a stagnation zone that is shared by the wells. If the wells are not properly spaced,
their individual capture zones will remain intact and the portions of the aquifer lying between adjacent capture
zones will be free to move on downgradient (Keely, 1984). Similarly, when two or more injection wells are
operating in unison, their individual rejection zones will coalesce to form a angle collective rejection zone only if
their spacing is appropriately close.
A number of approaches have been used to determine the optimal spacing of pumping and injection wells.
The most traditional approach is the use of well hydraulics formulas to estimate the position and shape of the
2
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zone of pressure influence surrounding a well (Lohman, 1972; Todd, 1980; EPA, 1985; Driscoll, 1986). This
information is usually obtained as point estimates of the drawdown caused by pumping wells or the pressure
increase caused by injection wells. When taken together with pre-operational water levels, estimated drawdowns
and pressure increases can be used to generate net/resultant water level elevation maps for the operating
conditions of a pump-and-treat remediation. Capture zones and rejection zones are identifiable on net water
level elevation maps by their elevation divides and closed contours; but the resolution of their positions by this
approach is subject to a number of errors due to the imperfect nature of well hydraulics theory to date.
4. Well Hydraulics
The mechanics of pumping and injection wells have been studied intensively for a number of years, but there
are still a number of gaps in the theories that describe their hydraulic effects. For instance, the Theis equation is
completely satisfactory for describing the time-development of pressure changes induced by a flowing well in a
confined aquifer, provided that the well is screened throughout the entire saturated thickness of the aquifer and
that certain other assumptions are met No such equation exists to describe satisfactorily the time-development
of pressure changes induced by a flowing well in an unconfined aquifer (also, water-table or phreatic aquifer).
Nor does an equation exist for the satisfactory description of partial penetration and partial screening effects in
unconfined aquifers. The latter theoretical shortcomings are not inconsequential, since most pump-and-treat
remediations involve the use of partially penetrating, partially screened wells in unconfined aquifers and
therefore have varying hydrodynamic effects over time.
Numerical models can be used in lieu of the Theis equation or other analytical models to determine the
effects of pumping and injection wells, and they offer the advantage of being able to incorporate complex aquifer
boundaries; but numerical models have their limitations too. The ability to incorporate complex boundary
conditions is useful only if one can establish accurately the type and orientation of the boundary. Moreover,
numerical solutions are grid-block-by-grid-block discretized approximations of the real world, as opposed to the
exact — but highly simplified — representations offered by analytical models. Numerical models allow for more
sophisticated representations than analytical models, but they may incur errors (such as numerical dispersion
and numerical oscillation) that are not encountered with analytical models.
Given the preceding, it may seem that neither the theories nor the tools exist to design properly pump-and-
treat remediations; but this is not so. Rather, it is important to place what is known in perspective; the
magnitude of errors arising from the simplifying assumptions of analytical models and the discrete
3
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approximations of numerical models must be understood and estimated on a site-specific basis. Just as
importantly, the natural processes that control contaminant movement (e.g., advection, dispersion, sorption,
biotransformation, etc.) must be identified and their relative roles estimated for each situation (Keely and
others, 1986).
Conventional Pump-and-Treat (P&T) Remediations
Conventional remediations of ground-water contamination often involve continuous operation of an
extraction-injection wellfield. In these remedial actions, the level of contamination measured at monitoring wells
may be dramatically reduced in a moderate period of time, but low levels of contamination usually persist. In
parallel, the contaminant load discharged by the extraction wellfleld declines over time and gradually approaches
a residual level in the latter stages (Figure 1). At that point, large volumes of water are being treated to remove
small quantities of contaminants. Depending on the reserve of contaminants within the aquifer, this may cause a
remediation to be continued indefinitely, or it may lead to premature cessation of the remediation and closure of
the site. The latter is particularly troublesome because an increase in the level of ground-water contamination
may follow (Figure 2) if the remediation is discontinued prior to removal of all residual contaminants.
There are several contaminant transport processes that are potentially responsible for the persistence of
residual contamination and the kind of post-operational effect depicted in Figure 2. In order to generate such
effects, releases of contaminant residuals must be slow relative to pumpage-induced water movement through
the subsurface. Transport processes that generate this kind of behavior during continuous operation of a
remediation wellfield include (i) diffusion of contaminants within spatially variable sediments, (ii) hydrodynamic
isolation, (iii) sorption-desorption, and (iv) liquid-liquid partitioning.
1. Advection vs. Diffusion
Variations in rates of advection that are caused by spatial variability of hydraulic conductivity result in rapid
cleansing of higher permeability zones by extraction wellfields, but only diffusion-controlled (slow) removal of
contaminants from of low permeability zones (Figure 3). The situation is similar, though reversed, for in-situ
remediations that require the injection and delivery of nutrients or react ants to the zone of intended action;
access to contaminants in low permeability sediments is diffusively restricted.
4
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Figure 1.
5
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Figure 2.
6
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Figure 3.
7
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The orders-of-magnitude greater surface area of the low-permeability sediments allows significantly greater
amounts of contaminants to accumulate on them during the pollution event/activity, in contrast to much lower
accumulations of contaminants in high permeability sediments. Hence, the majority of contaminant reserves
may be available only under diffusion-controlled conditions in many heterogeneous settings.
2. Hydrodynamic Isolation
The operation of any wellfield in a moving aquifer results in the formation of stagnation zones downgradient
of extraction wells and upgradient of injection wells. The stagnation zones are hydrodynamically isolated from
the remainder of the aquifer, so mass transport within the isolated water may occur only by diffusion. If
remedial action wells are located within the bounds of a contaminant plume, such as for the removal of
contaminant hot-spots, the portion of the plume lying within their associated stagnation zones will not be
effectively remediated.
3. Sorption influences
For sorbing compounds, the number of pore volumes to be removed depends not only on the sorptive
tendencies of the contaminant but also on whether flow rates during remediation are too rapid to allow
contaminant levels to build up to equilibrium concentrations locally (Figure 4). If insufficient contact time is
allowed, the affected water is advected away from sorbed contaminant residuals prior to reaching equilibrium
and is replaced by fresh water from upgradient. This method of contaminant removal generates large volumes
of mildly contaminated water where small volumes of highly contaminated water would otherwise result.
4. Liquid-Liquid Partitioning
When non-aqueous phase liquid (NAPL) residuals are trapped in pores by surface tension, diffusive
liquid-liquid partitioning controls dissolution of the NAPL's into the ground water. Similar to the process with
sorbing compounds, flow rates during remediation may be too rapid to allow aqueous saturation levels of the
partitioned contaminant to be reached locally (Figure 5). If insufficient contact time is allowed, the affected
water is advected away from the NAPL residuals prior to reaching chemical equilibrium and is replaced by fresh
water from upgradient. Again, this process generates large volumes of mildly contaminated water where small
volumes of highly contaminated water would otherwise result.
8
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Figure 4.
9
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Figure 5.
&
10
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Figure 6.
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Innovative P&T: Pulsed Pumping
Pulsed operation of hydraulic systems is the cycling of extraction or injection wells on and off in active and
resting phases (Figure 6). The resting phase of a pulsed-pumping operation can allow sufficient time for
contaminants to diffuse out of low permeability zones and into adjacent high permeability zones, until maximum
concentrations are achieved in the higher permeability zones; or, for sorbed contaminants and NAPL residuals,
sufficient time can be allowed for equilibrium concentrations to be reached in local ground water. Subsequent to
each resting phase, the active phase of the pulsed-pumping cycle removes the minimum volume of contaminated
ground water, at the maximum possible concentrations, for the most efficient treatment. By occasionally cycling
only select wells, their stagnation zones may be brought into active flowpaths and remediated.
1. Special Considerations
Pulsed operation of remediation wellflelds incurrs certain additional costs and concerns that must be
compared with its advantages for site-specific applications. During the rest phase of pulsed-pumping cycles,
peripheral gradient control may be needed to ensure adequate hydrodynamic control of the plume. In an ideal
situation, peripheral gradient control would be unnecessary. Such might be the case where there are no active
wells, major streams, or other significant hydraulic stresses nearby to influence the contaminant plume while the
remedial action wellfleld is in the resting phase. The plume would migrate only a few feet during the tens to
hundreds of hours that the system was at rest, and that movement would be rapidly recovered by the much
higher flow velocities back toward the extraction wells during the active phase.
When significant hydraulic stresses are nearby, however, plume movement during the resting phase may be
unacceptable. Irrigation or water-supply pumpage, for example, might cause plume movement on the order of
several tens of feet per day. It might then be impossible to recover the lost portion of the plume when the active
phase of the pulsed-pumping cycle commences. In sudi cases, peripheral gradient control during the resting
phase would be essential. If adequate storage capacity is available, it may be possible to provide gradient control
in the resting phase by injection of treated waters downgradient of the remediation wellfleld. Regardless of the
mechanics of the compensating actions, their capital and operating expenses must be added to those of the
primary remediation wellfleld to determain the complete cost of pulsed pumping.
2. The Pulsed Pumping Project
EPA's Risk Reduction Engineering Laboratory in Ondnnati initiated a three-phased project for evaluation
of the pulsed pumping technique in December of 1988. Administration of the project is overseen by the Center
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for Hazardous Waste Research at the University of Cincinnati, while the technical direction is the responsibility
of Dr. Joseph F. Keely (Portland, Oregon). The primary objective of the study is to investigate the potential for
the pulsed pumping method to improve the efficiency of contaminant removal and the cost-effectiveness of
hydrodynamically-dependent remediations, specifically including both pump-and-treat operations and in-situ
operations.
The Phase 1 efforts consist of reconnaissance surveys and preliminary computations. The results of these
will be used to prepare a decision-support document for the Agency's use in determining the feasibility and
attractiveness of sponsoring Phase 2 and Phase 3. Phase 2 concentrates on detailed analyses of pulsed-pumping
operations at one or more Superfund sites where remediations have already commenced. Phase 3 is a field
demonstration of pulsed pumping at an unremediated Superfund site, including all design and operation aspects.
The proposed approach to accomplishing the goals of Phase 1 consists of:
(1) examination of the literature of several technological fields,
(2) identification of candidate sites for Phase 2 and Phase 3,
(3) preparation of conceptual designs for pulsed pumping operations, and
(4) analysis and discussion of associated economic and technical aspects.
There is great need to review the literature from several technological fields. This can be done most efficiently
by searching computerized databases, and this is planned. One should not underestimate the value of
information not published in the scientific literature, however. The reports generated from investigations of
hazardous waste sites, for example, are usually public documents that are rarely synopsized for trade journals
and formal publications.
A number of remediations that are underway that incorporate some of the principles of pulsed pumping.
For instance, pumpage from contaminated bedrock aquifers and other low permeability formations results in
intermittent operation by default; the wells are pumped dry even at low flow rates. In such cases, the wells are
operated on-demand with the help of fluid-level sensors that trigger the onset and <^«catinn of pumpage. The
latter is a far cry from the kind of optimization that is possible in a contaminant removal sense; the onset and
cessation of pumpage need to be keyed to contaminant concentration levels. Nevertheless, the examination of
RI/FS and other documents that describe on-demand systems in use at waste "trs will provide useful
information, and help to determine the criteria to be used in selecting panHiHatf sites for Phase 2 and Phase 3.
The Agency's decision to proceed with Phase 2 and Phase 3 depends on the idftntifinrt'pp of candidate sites.
13
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EPA's Regional Offices will be contacted by the project participants to discuss the project with site managers
and to examine site documents. After careful review and cross-comparison of the information from the Regions,
three Regions will be chosen for field visits. One or more sites in each Region selected will be visited and
examined in detail, with video recording of current site conditions and activities, and interviews with responsible
officials and site managers. Additionally, Dr. Keel/s involvement in the Remediation Performance Project
sponsored by EPA-RSKERL (and other consulting ventures) will provide additional opportunities to visit
promising sites.
Work on the candidate sites will include preparation of conceptual designs of pulsed-pumping scenarios for
each. These wall be explored with computer simulations; e.g., by examining combinations of extraction wells and
injection wells under hydrogeologic assumptions appropriate to the respective sites. Note that while the
computer simulations will generate useful insights, the programs used to generate them are based on idealized
theoretical assumptions (e.g., instantaneous contact of contaminants with all waters of a certain stratum). The
result is that clean-up efficiencies predicted by conceptual simulations will likely exceed what is achievable in
reality. For that reason, the Phase 1 simulations are to be used primarily to optimize generalized wellfield design
strategies and economic trade-offs. Intensive modeling efforts are reserved for analysing and fine tuning
selected Superfund remediations in Phase 2, and for design and management of a field demonstration at an
unremediated site in Phase 3.
Monitoring the Performance of P&T Remediations
There are serious unresolved questions about how one ought to monitor the performance of pump-and-treat
remediations. Neither contaminant distributions nor velocity distributions are constant throughout the zone of
action (that portion of an aquifer that is actively being manipulated by the pumping wells). Consequently,
monitoring strategies must be cognizant of the need to detect rapid, sporadic changes in the quality of ground
water at any specific point in the zone of action. What this means in practice is that tracking the effectiveness of
pump-and-treat remediations is quite complicated chemically. The frequency and density of samplings must
consider the detailed flowpaths generated by the remediation wellfield, including the variations in susceptibility
to transport processes along those flowpaths. It also means that it may be necessary to move the chemical
compliance points (or corrective action monitoring pouts) during the course of a remediation.
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Nor are evaluations of the hydrodynamic performance of remediation wellfields easily accomplished. For
example, it is usually required that an inward hydraulic gradient be maintained at the periphery of a contaminant
plume. This requirement is imposed to ensure that no portion of the plume is free to migrate away from the
zone of action. To assess this performance adequately, the hydraulic gradient must be measured accurately in
three dimensions between each pair of adjacent pumping or injection wells. The design of an array of
piezometers (small diameter wells with very short screened intervals, that are used to measure the pressure head
of selected positions in an aquifer) for this purpose is not as simple as one might fust imagine. Two points define
a line, and three points define a plane; but many more are needed to define the convoluted surface that develops
between adjacent pumping or injection wells. Not only are there velocity divides in the horizontal plane near
active wells, but in the vertical plane, too, because the pressure influence of each well extends to only a limited
depth in practical terms.
Principles for the practical use of remediation wellfields and other ground-water clean-up technologies are
thus evolving still, and are highly dependent on site-specific knowledge of the influence of transport processes on
contaminant levels. There is still much to be learned about how to design and implement highly specific and
cost-effective remedies. Far more could be accomplished than is typically done, however, if the transport
processes that govern the environmental behavior and treatability of contaminants were investigated actively at
each site. The past history of conducting a bare minimum of field characterization efforts (other than chemical
samplings) has not led to complete or satisfactory remediations, generally. Such approaches appear penny-wise
/ pound-foolish in retrospect, and are yielding to transport-process-intensive approaches as the ground-water
profession strives for meaningful improvements in the specificity and cost-effectiveness of remediations (Keely
and others, 1986).
There are a lot of misconceptions and misunderstandings regarding the effects that key hydrodynamic,
abiotic/chemical, and biological processes have on the transport and fate of contaminants in the subsurface.
Some of these, such as the confusion over capture zones and drawdown cones of pumping wells that was
discussed earlier in this document, are relatively easy to address by educational efforts. Others, such as the
controversy over just what hydrodynamic dispersion is in a physical sense, or the way that sorption and
biotransformation rate constants ought to be derived and subsequently used in predictive models, can be
addressed only by applied research.
15
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1. Compliance Criteria
Extraction and injection wells used in ground-water contamination remediations produce complex flow
patterns, where previously there were comparatively simple flow patterns. Historical trends at local monitoring
wells are thereby rendered useless when remediation commences. The complex flow patterns generated by
remediation wellfields present great challenges in terms of characterization of the altered transport pathways.
Hence, there is often a need for more data to be generated during the remediation than were generated during,
the entire Rl/FS process at a site, and for those data to require much more sophisticated interpretations. The
key controls on *Jie quality of data obtained for interpretations are the compliance criteria that are selected and
the compliance point locations at which those criteria are to be applied.
It is essential to recognize the many kinds of compliance criteria actually in use today. There are three
major kinds of compliance criteria: chemical, hydrodynamic, and administrative control. Chemical compliance
criteria are MCi's, ACL's, Detection Limits, and Natural Water Quality. Hydrodynamic compliance criteria are
such things as (i) demonstrated prevention or minimization of infiltration through the unsaturated zone, (ii)
maintenance of an inward hydraulic gradient at the boundary of a plume of ground-water contamination, and
(iii) providing minimum flows in a stream. Administrative control compliance criteria include (i) effective
implementation of drilling bans and other access- limiting administrative orders, (ii) proof of maintenance of site
security, and (iii) reporting requirements, such as frequency and character of operational and post-operational
monitoring. Almost any combination of chemical, hydrodynamic, and administrative control compliance criteria
may be appropriate for a specific compliance point, depending on its location.
The most widely known kind of compliance point is located a short distance downgradient of the plume.
The exact location is chosen so that: (i) it is neither in the plume nor in adjacent areas that may be affected by
the remediation, (ii) it is in an uncontaminated portion of the strata through which the plume would migrate if
the remediation failed, and (iii) its location minimizes the possibility of detecting other actual or potential
sources of contamination (e.gM it is not located too far away, to be relevant to the target site only). Data gathered
there serve to indicate out-of-control conditions when a portion of the plume escapes the remedial action. The
compliance criteria typically specified for this kind of compliance point are Natural Water Quality (Background)
or Detection limits. This kind might be referred to as a Background Compliance Point
Another common kind of compliance point is represented by public water supply wells
downgradient of a plume. The locations of these points are not negotiable; they are where they are. The
16
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significance of their use is in assuring the quality of water delivered to consumers, as it relates to specific
contaminants associated with the target site. The compliance criteria typically specified for this kind of
compliance point are MCL's, MCLG's, and maintenance of existing quality. An appropriate name for this kind
is Public-Supply Compliance Point
A third kind of off-plume compliance point commonly established is one for determinations of hydraulic
gradients. This kind is comprised of a cluster of small diameter wells that have very short screened intervals, and
is usually located just outside the perimeter of the plume and along a line running between two plume
remediation wells. Water level elevations are measured and used to prepare detailed contour maps from whicl.
determinations of the direction and magnitude of the local hydraulic gradients can be made. This kind might be
referred to as Gradient Control Compliance Points.
Less commonly known is the kind of compliance point represented by monitoring wells located within the
perimeter of the plume. Most of these are installed during the site investigation phase (prior to the
remediation), but others may be added subsequent to implementation of the remediation; they are used to
monitor the progress of the remediation within the plume. These can be subdivided into compliance points
located on-site (within the property boundary of the facility that contains the source of the plume of
contamination), and those located off-site (beyond the facility boundary, but within the plume); the latter kind
assumes that the plume has migrated beyond the facility boundary.
Because of its proximity to the source of contamination, and the tpyhnlral infeasibility of complete removal
of the source at many sites, the compliance criteria for an on-site compliance point range from Natural Water
Quality to Alternate Concentration Limits that represent the best that can be done cost-effectively. In addition,
hydrodynamic compliance criteria are often associated with on-site compliance points; e.g., moisture-content
determinations may be used to evaluate the effectiveness of a cap in reducing or eliminating infiltration through
contaminated soils in the unsaturated zone. An explicit name for these is On-Site Plume Compliance Point
Similarly, one can refer to the remaining compliance points located within the perimeter of the plume as Off-Site
Plume Compliance Points. The compliance criteria applied to these tend closer to Natural Water Quality than is
the case on-site, but again are closely tied to technology-driven ACL's; more stringent criteria are usually
appropriate, because the source is not included.
As discussed in the preceding paragraphs, each kind of compliance point has a specific and distinct role to
play in evaluating the progress of a remediation. The information gathered is not limited to chemical identities
17
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and concentrations, but includes other observable or measurable items that relate to specific remedial activities
and their attributes. In choosing specific locations of compliance points, and criteria appropriate to those
locations, it is essential to recognize the interdependent of the compliance criteria for different compliance
points. For example, one cannot justify liberal ACL's on-site and have realistic expectations of meeting more
stringent ACL's off-site; the facility boundary will not magically dilute the residual contaminants leaving the
on-site area after the remedial action ceases operation. Similarly, one cannot expect Background Compliance
Points to remain free of contamination if the off-site plume ACL is chosen inappropriately.
In addition to the foregoing, one must decide what method(s) should be used to determine statistical
variations in each parameter measured, what cut-off(s) should be applied (e.g., 95% confidence interval),
whether they apply to each compliance point or can be averaged, what method to use to indicate that the
maximum clean-up has been achieved (e.g., the zero- slope approach), and so on.
2. The Remediation Performance Project
The National Center for Ground "Water Research (NCGWR) develops and disseminates information on the
transport and fate of contaminants in the subsurface. NCGWR's activities are funded through EPA's R.S. Kerr
Environmental Research Laboratory (RSKERL), which has a similar mission with respect to contamination of
the subsurface. The Remediation Performance Project is a multi-phase effort initiated by RSKERL to increase
the avaliabiiity of information about strategies and data presentation/interpretation methods useful for
evaluations of the ongoing performance of ground-water contamination remediations.
Phase 1 of the Remediation Performance project began 1 August 1987 and is scheduled for completion by 31
December 1988. The Phase 1 tasks are focused on collecting information about the adequacy of monitoring
networks and compliance criteria now in use at Superfund sites, and about the maimer in which the resulting
data are interpreted and presented for decision making. Special emphasis is also being placed on
transport-process data needs in the use of assessment models for decision making.
Phase 2 focuses on development of the Remediation Operational-Performance Evaluation Methodology
(ROPEM) by which monitoring well network designs and compliance criteria can be selected and used
effectively, so that the ongoing performance of a remediation can be tracked accurately. ROPEM will provide
worked examples and recommendations for the use of mathematical modeling (e.g., flowline analyses, mass
balances, boundary influences), statistical analyses (e.g., regressions, correlations, ANOVA), graphical analyses
(e.g^ phase diagrams, Stiff plots, Piper diagrams), and theoretical approaches (e.g., structure-activity
18
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relationships, sedimentology, gcomorphology). The potential power of ROPEM will be illustrated by applying it
to existing Chem-Dyne and United Chrome Products Superfund sites' data; this will include calibrating
mathematical models to both sites, as well as performing statistical and graphical analyses on data from these
sites.
Complete field validation of ROPEM wall require enhanced characterization of these or other sites.
Specifically, the enhanced site characterization should lead to a detailed understanding on the transport
pathways, the mass of contaminants in reserve on subsurface solids, the total organic carbon content of those
solids, and the susceptibility of indigenous organisms to engaging in biotransformation of the contaminants.
Such characterization efforts provide the optimal level of transport process data recommended by ROPEM.
These and other field evaluation activities are reserved for Phase 3.
References
19
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ON
3
CL
OFF
MAX
o
h
<
cc
H
Z
LLI
O
Z
o
o
o —
TIME
Figure 2. Potential ground-water contamination response to cessation of continuous
pumpage. The three year window is a typical regulatory criterion for
maintenance of minimum remediation concentrations for site closures.
-------
ON
3
Q.
o
h-
<
DC
H
Z
UJ
o
z
o
o
OFF
MAX
RESIDUAL
CONCENTRATION
—
I
I —
*1
— TIME -
Figure 1. Effluent Concentration Pattern for Continuous Wellfield Operations
-------
Figure 3. Diffusive release of contaminants from low permeability sediments to
adjacent high permeability sediments
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\ ORGANIC CARBON OR
MINERAL OXIDE COATING
EQUILIBRIUM CONCENTRATION
o
H
<
oc
H
z
ID
o
z
o
o
SLOW
DESORPTION
INITIAL
RAPID
DESORPTION
TIME
Figure 4. Concentration of ground-water contaminants controlled by
de-sorption kinetics
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ADVECTION
MOLFCULAR
DIFFUSION
ADVECTION
GROUNDWATER VELOCITY
Figure 5. Dependence of ground-water contamination level on partitioning
of non-aqueous phase (P) residuals as a function of increasing
ground-water velocity
-------
Figure 6. Effluent concentrations for a pulsed pumping remediation. Residual and
maximum contaminant levels decline with each cycle.
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IN-SITU SOIL WASHING AND FLUSHING TECHNOLOGIES
Thomas C. Sale, CH2M Hill, Denver, Colorado
-------
PRESENTATION OUTLINE
IN SITU SOIL WASHING AND FLUSHING TECHNOLOGIES
Physical Properties and Behavior of Creosote Oil
o Physical properties
o Occurrence and distribution
o Pore space saturation
o Effects of pore saturation on permeability
Primary Recovery of Creosote Oil
o Literature review
o Design concepts
o Laramie Tie Plant case study
1987 field pilot
— 1988 system scale up
Enhanced Removal of Creosote Oil
o Review of potentially applicable techniques
o Surfactant systems
Reduction of interfacial tensions
Mobility ratios
o Laboratory studies
o Environmental concerns
o Laramie Tie Plant case study
1983 field pilot
— 1989 system scale up
Summary
o Evaluation of feasibility at other sites
o Estimation of costs
DEN/40R/102
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IN SITU REMOVAL OF WASTE WOOD-TREATING
OILS FROM SUBSURFACE MATERIALS
TOM SALE
KEITH PIONTEK
PRESENTED AT THE U.S.'EPA FORUM ON REMEDIATION OF
WOOD-PRESERVING SITES, OCTOBER 1988, SAN FRANCISCO
CH2M HILL
DENVER, COLORADO
DEN26864.AO
DEN/109R/001.1
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INTRODUCTION
A common condition at wood-treating facilities is soils and/or
aquifer materials contaminated by waste wood-preserving oils.
Contamination may vary from soil stained black with residual
oils to areas in which oils will freely flow from the soils
into a well. Often these contaminated materials occur at
depths or in volumes that limit the feasibility of excavation
and at concentrations that limit the effectiveness of pump-
and-treat remediation strategies. Under these conditions,
in situ technologies can be applicable for site remediation.
This paper discusses in situ methods for removal of waste
wood-preserving oils from the subsurface using waterfloods
and enhanced recovery technologies.
In 1980, researchers estimated that 631 active wood-preserving
facilities existed in the United States. In addition to
these active facilities, thousands of other wood-treating
facilities have been abandoned. Primary materials used to
treat wood products at these facilities fit into the categor-
ies of creosote, pentachlorophenol, and arsenic-based systems.
Of these, pentachlorophenol and creosote systems are oil
based while the arsenical systems are water based. Contami-
nation is more commonly associated with pentachlorophenol
and creosote systems due to greater periods of historical
use, a higher overall volume of use, and the formation of
oil water emulsions during wood treatment.
Wood preservatives are commonly forced into wood products in
pressurized retorts. As the oil-based systems move into the
wood products, water is displaced from the wood, commonly
forming an oil-water emulsion with the wood-treating oils.
Historically, these emulsions have been managed, as per the
standards of the era, in facilities such as unlined ponds
which often allowed waste wood-treating oils to migrate to
subsurface materials. Other potential sources of subsurface
contamination at wood-treating facilities include drip pads
without collection systems, leaking tanks, leaking pipelines,
and fluids spilled during liquid transfers.
Once they are in the subsurface materials, the waste oils
sink through unsaturated porous media and tend to become
perched above strata of low permeability. Creosote systems
are typically denser than water, therefore, they tend to
continue sinking through saturated porous media until they
reach a low permeability boundary. Once at this boundary,
if it exists, further migration of creosote—based wood-
preserving oils is governed by the topography of the boun-
dary . The oils often accumulate within topographic lows.
Pentachlorophenol systems are typically less dense than water;
therefore, they tend to accumulate on top of the water table.
DEN/109R/002
1
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Removal of waste wood-treating oils from subsurface materials
is often one of the primary obstacles to cleanup of wood-
treating facilities. The remainder of this article focuses
on recovery of creosote-based waste wood-treating oils from
subsurface materials. Although this is the focus, much of
the information also applies to other types of oil contami-
nation in porous media. Specifically discussed are: (1) the
physical properties of creosote-based wood-treating oils and
how they impact remediation, (2) the design concepts and
potential effectiveness of waterfloods, and (3) the poten-
tial for using enhanced recovery methods including,
surfactant-based waterfloods. Where applicable examples are
presented from laboratory and field studies.
PHYSICAL PROPERTIES AND
BEHAVIOR OF CREOSOTE OIL
Prior to a discussion of methods for recovery of creosote-
based waste wood-treating oils, an understanding of contam-
inant mobility and distribution, based on the physical
properties of the oils, needs to be developed.
Creosote-based wood-preserving oils are derived from frac-
tional distillation of coal tars produced during coking of
coal. The oils contain a complex mixture of polynuclear
aromatic hydrocarbons (PNAs), primarily consisting of two,
three, and four fused-ring organic compounds. In addition,
creosote-based wood-treating oils either contain or are
mixed with a large fraction of carrier oils, consisting pri-
marily of aliphatic hydrocarbons. The carrier oil fraction
enhances the penetration of the PNA compounds into wood prod-
ucts during treatment.
Typical creosote based oils are denser than water (e.g.,
1.02 to 1.04 g/cm ). Consequently, the oil will sink within
water saturated porous media given sufficient volumes of oil
and formation permeability. Viscosities observed by the
authors have been in the range of 50 and 70 centipose
(approximately 50 to 70). This causes the oils to flow slower
than water under an equivalent gradient. In addition, the
oil is highly immiscible with water which causes the oils to
be immobile within porous media except when present at high
concentrations.
The degree of oil saturation within the pore space of the
alluvium, affected by the oil's viscosity and immiscibility
with water, plays a critical role in defining the oil's mobil-
ity. Laboratory work performed by MTARRI and Surtek, Inc.,
both of Golden, Colorado, defined the fraction of oil present
in an alluvial sand that is recoverable and the effect of
oil saturation on permeability with respect to oil and water.
DEN/109R/002
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The laboratory work consisted of bench-scale linear core
floods using coarse sands and oil from a wood-treating site.
The procedure involved sequential flooding of the soil cores
with water, with oil, and finally with water again. The
following results were obtained:
o The maximum oil saturation that could be achieved
during oil flooding of the cores was about two-
thirds of the pore space. The other one-third of
the pore space remained filled with water, which
was held to the sand grains, immobile under an oil
flood (referred to as residual water).
o After the oil flood, a waterflood of the cores
could displace about one-half of the oil present,
leaving about one-third of the pore space filled
with oil. This oil was held in place primarily
due to the interfacial tension between the fluids
and the capillary forces associated with the
aquifer matrix (referred to as residual oil).
Overall, the data indicate that in a coarse sandy soil, water-
floods can achieve a maximum 50 percent reduction in free-phase
oil. Figure 1 graphically presents these results.
During the core floods, the relative permeability of the
cores with respect to oil and water as a function of pore
saturation was also determined. These data indicated:
o The formation permeability with respect to oil is
at a maximum when the oil saturation of the pore
space is at a maximum. This finding is important
in that the mobility; therefore, the recoverability
of the oil is greatest when the formation permeabil-
ity with respect to oil is at a maximum.
o Formation permeability with respect to water is at
a maximum when water saturation of the pore space
is at a maximum. This finding is also important:
to maximize water production from a given interval,
oil saturation should be at a minimum.
Figure 2 presents the observed impact of oil pore saturation
on formation permeability. Intuitively, the described results
bear out: with lower fluid saturations, the cross-sectional
area for flow decreases and the tortuosity of the flow path
increases.
DEN/109R/002
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... (35.0"»>
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PERCENT OF PORE SPACE OIL SATURATED
¦ PERMEABILITY TO OIL
• PERMEABILITY TO H20
FIGURE 2
PERMEABILITY VERSUS % OIL SATURATION
-------
PRIMARY OIL RECOVERY
Where creosote-based wood-preserving oils are present above
residual saturation, primary oil recovery may be an appropr-
iate step in remediation of contaminated subsurface materials.
The overall concept is similar to recovery techniques used
in the petroleum industry, involving the use of waterfloods
to move oil to a recovery point.
Through primary or waterflood recovery, further migration of
free-phase oil can be inhibited and the volume of subsurface
contaminants can be reduced. In addition, oil recovery
through waterflood techniques may be an effective "first
step" in a more thorough cleanup of subsurface contamination
through use of more complex, enhanced in situ removal/treatment
technologies. A review of some of these technologies is
presented later in this paper.
FLOW-PATH MANAGEMENT
Efficient recovery of oils from porous media through fluid
delivery and withdrawals requires effective management of
the flow path along which the oils will be drawn toward the
recovery system. For oil to move toward a recovery system,
a gradient must be present and a continuous body of material
with sufficient permeability must exist for the oil to migrate
through. Simply stated through Darcy's equation, oil flow
is equal to formation permeability with respect to oil, mul-
tiplied by cross-sectional area available for flow, multi-
plied by the flow gradient. The limiting of any one of these
variables will severely restrict the efficiency of a water-
flood recovery system.
Flow gradients toward a recovery system are typically estab-
lished through pumping water from the formation in the vicin-
ity of the oil-recovery system. Formation permeabilities
with respect to oil can be optimized by maintaining a maxi-
mum formation saturation with respect to oil through the
interval in which the oil will migrate. This optimization
can be accomplished by allowing the oil to accumulate in a
fixed interval that coincides with the oil-recovery flow
path. Sufficient saturated thickness of the oil recovery
flow path can be maintained by controlled pumping of water
and oil from separate recovery systems at rates that prevent
the flow of the less viscous, more mobile water from truncating
the flow of the viscous oil.
An additional consideration in the management of the recovery
flow path is the limitations of oil movement into areas that
have not been previously unwetted by oil. As oil is drawn
into unwetted areas, large amounts of oil are retained by
the soils. The capacities of the soils to retain oil must
DEN/109R/002
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be satisfied before the flow of oil through the materials
will occur. Since residual adsorption capacities of soils
can be in the neighborhood of one-third of pore space, this
limitation can result in the loss of large volumes of mobile
free-phase oils that might have been recovered had they been
kept outside of unwetted areas. Another disadvantage of
moving oils into unwetted areas is that it increases the
volume of soils at residual saturation which may require
further, potentially expensive remediation.
PRIMARY OIL RECOVERY CASE STUDY
Faced with the need to recover creosote-based waste wood-
treating oils from a shallow, alluvial aquifer in the wes-
tern United States, CH2M HILL designed, operated, and
evaluated a recovery system using the above concepts. The
following text reviews the system design and pilot test
results. Additional information can be found in Sale, et
al. (1988).
CH2M HILL's first step in addressing recovery of oil from
the site was to investigate the existing recovery system.
This system used single pumps in large-diameter wells. When
oil accumulated in the wells, the pump would operate until
the oil was purged from the well. Over the system's 3-year
operational period, limited production was achieved. Factors
limiting oil production include:
o The pumps operated infrequently; therefore, the
only forces moving oil to the recovery wells were
gravity and the local groundwater gradient.
o Fluids were forced to flow into the wells through
a restricted screen at the base of the alluvium.
During pumping, the flow of the more mobile water
effectively truncated the flow of oil in the
restricted screen interval.
Based on the limited success of the existing system and the
understanding of its shortcomings, CH2M HILL developed and
field tested an innovative oil recovery system. The general
objectives of the pilot test were (1) to evaluate the feasi-
bility of recovering the mobile creosote-based wood-treating
oils from the shallow aquifer at the site and, if successful,
(2) to obtain sufficient design data to proceed to a scaled-up
or full-scale primary oil-recovery system design.
Dual Drainline Design Concept
Fluids could be pumped from the alluvium using either wells
or drainlines. To overcome the limited fluid production
that could be achieved in the shallow alluvium, we used hori-
zontal drainlines instead of wells for fluid recovery. For
recovery of the viscous, denser-than-water, immiscible
DEN/109R/002
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creosote-based wood-treating oil, we selected a system of
dual drainlines to optimally manage oil and water flow and
formation saturations.
Diagrams A through D in Figure 3 present cross sections that
depict site conditions and the hydraulic concepts associated
with the dual drainline system. Diagram A shows fluid distri
bution under static conditions and the physical location of
the drainlines. In this case, concentrated waste wood-
preserving oil has accumulated at the base of .the alluvium
and is overlain by water.
Diagram B shows the fluid distribution with only the lower
oil recovery drain (ORD) being pumped. Under this stress,
water and oil are produced, but the majority of the pore
space surrounding the ORD is occupied by water. This con-
dition limits the formation permeability with respect to oil
and effectively truncates or limits the flow of oil to the
ORD.
Diagrams C and D outline the dual drainline approach, which
overcomes the drawback of truncated flow illustrated in
Diagram B. In Diagram C, only the water table depression
drainline (WTDD) is being pumped. It produces primarily
water and induces a hydraulic flow gradient in the under-
lying oil-saturated portion of the aquifer. Because oil
saturation in the lower portion of the aquifer is at its
maximum, the formation in this interval has its highest
potential permeability with respect to oil. The oil's
mobility within the formation is optimized (1) by the grad-
ient that results from pumping the overlying water, (2) by
the formation's optimal permeability to oil that results
from not drawing water through the oil-saturated interval,
and (3) by the increased thickness of the flow path avail-
able for oil migration.
The net result of pumping only the WTDD is that oil is drawn
toward and accumulates beneath the WTDD. Diagram D shows
the combined pumping of the WTDD and the ORD. If flow rates
are properly managed, this combination results in the oil
drawn toward the recovery system (through pumping the WTDD)
being removed as it accumulates (through pumping the ORD).
Another advantage of the dual drainline approach is that a
large degree of the needed oil-water separation is accomp-
lished below ground. This minimizes the requirements for
aboveground oil-water separation facilities.
Pilot Test Results
This design concept was tested in a pilot-scale application
at a wood-preserving site. The actual ORD and WTDD installed
at the site were constructed of 15-foot lengths of 4-inch
DEN/109R/002
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OIL DISTRIBUTION
GROUND SURFACE
« GROUNDWATER SURFACE
WATER TABLE DEPRESSION
OIL SURFACE rt DRAINLINE (WTDD) • THE OIL, BEING SLIGHTLY DENSER THAN
j muaw 2 . ¦ ... GROUNDWATER, HAS ACCUMULATED AT
:••••• OIL ¦ ;-.OIL ftECOYEh.Y DRAINLINE (ORD) thf or tup a, . ..u.nu
Aw
BEDROCK
OIL RECOVERY WITH A
GROUND SURFACE
n.n M Va w/V CU.-V'1"
ORD BEDROCK
SINGLE RECOVERY LINE
PUMPING ONLY THE ORD RESULTS IN
THE MORE MOBILE GROUNDWATER
TRUNCATING THE FLOW OF THE MORE
VISCOUS OIL TO THE RECOVERY LINE
OIL RECOVERY WITH A
GROUNDWATER
OIL SURFACE
GROUND SURFACE
SURFACE
"VVV ^
BEDROCK
DUAL DRAINLINE TECHNIQUE
• DRAWDOWN OF THE OVERLYING WATER
TABLE BY PUMPING THE WTDD
RESULTS IN MOUNDING OF THE
OIL BENEATH THE WTDD
GROUND SURFACE
J>RO^*y., - r \ T.1
wv'-1' KW'i'J'
BEDROCK
PUMPING FROM BOTH THE WTDD AND
ORD INDUCES OIL FLOW TO THE ORD
SEPARATE PRODUCTION OF OIL AND
GROUNDWATER REDUCES ABOVEGROUND
SEPARATION REQUIREMENTS
A FLOW PATH OF MAXIMUM
FORMATION PERMEABILITY TO OIL
IS ESTABLISHED AT THE BASE
OF THE ALLUVIUM
FIGURE 3
DUAL DRAINLINE CONCEPT
-------
slotted PVC pipe. The WTDD and ORD were located approxi-
mately 8 and 10 feet below grade. Materials present in the
alluvium range from fine-grained sands and silt at the sur-
face to coarse gravel at the base, which is located about
10 feet below grade. Underlying the alluvium is a silty,
shale, which acts as a barrier to vertical migration of the
wood-treating oils.
During the 29-day primary oil recovery pump test,
10,300 gallons of wood-treating oil (with a water content of
less than 0.1 percent) were recovered. In addition, about
770,000 gallons of water were produced, treated, and
recharged into the alluvial aguifer. Figure 4 shows cumu-
lative oil and water production.
Pumping rates from the WTDD and ORD were varied during the
test to gain information about optimum system operation and
hydraulic responses of oil and water in the aquifer to dif-
ferent pumping stresses. Initial pumping rates of
11.3 gallons per minute (gpm) from the WTDD and 1.2 gpm from
the ORD were selected, based on a trial run conducted during
system checkout.
Pumping rates from the WTDD were increased 6 times during
the test to a maximum rate of 40 gpm. The 40-gpm rate, which
was approximately 2.6 gpm per foot of drainline, potentially
represents the flow rate at which the oil-water interface
between drainlines became unstable, causing oil and water
layers to mix regardless of their densities.
011 production from the ORD varied because of differences in
formation conditions and different rates of water production
from the WTDD. In general terms, the oil-production-
versus-time graph (Figure 4) shows the following:
o Oil production rates exceeded 400 gallons per day
(gpd) for the first 2 test days. This
comparatively high rate reflects oil recovery in
the immediate vicinity of the drainlines.
o Increases in oil production corresponded to increases
in pumping from the WTDD. This correspondence
suggests that operation of the WTDD enhanced oil
migration toward the ORD.
o Oil recovery rates generally declined with time
after system startup and after each increase in
the WTDD pumping rate. This decline reflects oil
depletion in the immediate vicinity of the recovery
system as oil is drawn from greater distances.
DEN/109R/002
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CUMULATIVE WATER PRODUCTION VS. TIME
PRIMARY OIL RECOVERY PUMP TEST
800
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12
TIME SINCE TEST STARTED (DAYS)
CUMULATIVE OIL PRODUCTION VS. TIME
PRIMARY OIL RECOVERY PUMP TEST
i
16 20
TIME SINCE TEST STARTED (DAYS)
FIGURE 4
CUMULATIVE OIL
AND WATER PRODUCTION
-------
o Oil production rates remained above 200 gpd at the
end of the test, suggesting a strong potential to
sustain production for periods beyond the 29-day
pump test.
o The average recovery rate was 357 gpd throughout
the test. This rate indicates that where creosote
oil occurs above residual pore saturation, the oil
is mobile and can be recovered.
Based on the results of the pump test, a larger system was
installed and operated at the site. In a period of 4 months,
this system recovered 220,000 gallons of waste creosote-based
wood-treating oils from an area of approximately 2 acres.
IN SITU SOIL FLUSHING
A limitation of waterflooding or primary oil recovery is
that only a portion of the total free-phase oil in the sub-
surface can be removed, leaving a substantial residual oil
level in the subsurface. Due to the low solubility of the
residual creosote-based wood-treating oils and their presence
in percent concentrations, residual oil can act as a long-term
source of groundwater contamination.
This section covers factors that limit the effectiveness of
waterflooding. Enhanced oil removal methods, also called
in situ soil washing, which may be effective in achieving
lower residual contaminant levels are also described.
FACTORS AFFECTING RESIDUAL
OIL CONCENTRATIONS
Three primary factors contribute to the significant residual
oil concentrations remaining after waterflood oil recovery,
and make this residual difficult to flush from the subsurface.
These factors are (1) the water solubility of wood-preserving
oils; (2) interfacial tension (IFT) between the oil, water,
and soil; and (3) the relative permeability of oil and water.
The low solubility of residual creosote oils limits the effec-
tiveness of water based soil flushing methods because the
amount of oil that dissolves into water and is flushed from
the subsurface is insignificant in comparison with the residual
oil left in place.
IFT can be described as the unbalanced forces acting on a
droplet of free-phase hydrocarbon contamination. The lower
the IFT, the greater the tendency of the" droplet to be miscible
in groundwater. The result of high IFT is the retention of
the hydrocarbon on soil particles as opposed to its movement
when groundwater is swept through the soil pores.
DEN/109R/002
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Relative permeability can be described as the tendency of a
porous system to selectively conduct one fluid when two or
more fluids are present. The mobility ratio is the term
used to describe the effects of relative permeability in the
enhanced oil recovery industry. The mobility ratio is defined
as:
m = Vuo
where:
m = Mobility ratio
K = Effective permeability with respect to the
D displacing fluid
K =¦ Effective permeability with respect to the oil
U° = Viscosity of the displacing fluid
U0 = Viscosity of the oil
The higher the mobility ratio, the greater the tendency of
the displacing fluid to flow around rather than push out the
residual oil.
ENHANCED OIL-REMOVAL METHODS
Methods that have been developed or are considered for
enhanced removal generally are based on overcoming one or
more of the three factors described above. Many of these
methods are adaptations of techniques developed for use for
enhanced oil recovery (EOR) in the petroleum industry. These
methods include:
o In situ solvent extraction
o Hot water or steam flooding
o Carbon dioxide flooding
o Surfactant flooding
o Alkaline flooding
o Polymer flooding
Each of these methods is briefly described below.
In Situ Solvent Extraction
In situ solvent extraction involves flooding the subsurface
zone containing the residual oil with an organic solvent or
water containing an organic solvent. This technique is based
on increasing the solubility of the residual oil in the fluid
used for flushing the subsurface. This method is not gener-
ally considered highly feasible for the following reasons;
o Environmental concerns regarding injecting organics
that are effective as solvents into the subsurface
DEN/109R/002
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o Residual solvents left in the subsurface
o Difficulties in treating fluids withdrawn from the
subsurface that contain miscible mixtures of water,
solvent, and oil
o High project costs for implementation
Thermal Methods
The most commonly considered thermal methods are hot water
flooding and steam flooding. These methods rely on decreasing
the residual oil level by increasing contaminant solubility
and achieving a more favorable mobility ratio. Contaminant
solubility in the soil flushing solution is increased because
the water solubility of many organics increases at higher
water temperature. More importantly, the viscosity of free-
phase hydrocarbon decreases with increasing temperature.
Hydrocarbon recovery increases with decreasing viscosity
because of the corresponding decrease in the mobility ratio.
A major limitation in the use of thermal methods is that at
increased temperatures, denser-than-water free-phase oil may
be converted to a floating oil. The adverse effect of this
condition is that oil initially confined to a narrow lens
may float through and wet previously uncontaminated portions
of the subsurface. Costs may also be high due to the heat
loss that occurs as large volumes of subsurface materials
are heated.
The effectiveness of this technology in environmental appli-
cations is unknown.
Carbon Dioxide Flooding
Carbon dioxide flooding is an EOR technique that relies on
achieving a decreased mobility ratio. Carbon dixoide is
injected under pressure into an oil bearing zone. The vis-
cosity of the oil decreases as carbon dioxide dissolves into
the oil. Because this method relies on high pressures, it
would only be applicable at relatively large depths in a
confined strata.
The effectiveness of this technique in environmental appli-
cations is not known.
Surfactant Flooding
Soil flushing with surfactant solutions to extract hydro-
phobic organic contaminants appears to be one of the most
promising of in situ cleanup technologies. Aqueous surfac-
tant solutions are superior to water alone in extracting
hydrophobic contaminants. Both the detergency of aqueous
DEN/109R/002
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solutions and the efficiency by which organics are trans-
ported by aqueous solutions are thought by researches to be
improved by surfactant addition. The processes for improving
the detergency of aqueous solutions are preferential wetting,
increased contaminant solubilization, and enhanced contami-
nant emulsification (Envirosphere, 1983). The addition of
surfactants is thought to increase the efficiency by which
organics are transported in aqueous solutions by lowering
the interfacial tension between the aqueous and contaminant
phase, which facilitates the distortion of spherical oil
droplets as they pass through the soil.
Another reason the use of surfactants for in situ soil washing
applications appears promising is that numerous environmentally
safe and relatively inexpensive surfactants are available
commercially (Wagner and Kosin, 1984).
Alkaline Flooding
EOR research has identified an IFT reduction method that may
be much more cost-effective than the use of surfactants.
When in contact with certain hydrocarbon mixtures, alkaline
agents (e.g., sodium carbonate) can react to form surfactants
via a saponification reaction. Because these surfactants
are created at the aqueous-hydrocarbon interface, they can
effectively reduce the IFT. The use of a combination of
alkaline agents and surfactants may be the most cost-
effective way to reduce IFT and to enhance hydrocarbon
recovery (Cooke et al., 1974; Krumrine et al., 1980).
As in surfactant flooding, IFT reduction through the use of
alkaline agents is not likely to be effective if unfavorable
mobility ratios still exist. Other potential problems with
the use of alkaline agents may result from the high pH and
reactive nature of these solutions. These problems include
precipitation and resultant aquifer plugging, dispersal and
expansion of clays, and leaching of trace metals.
Polymer Flooding
Another commonly used EOR method that may have environmental
applications is polymer flooding. The oil-removal effec-
tiveness of the waterflood can be increased by adding polymer
to the water, which increases the viscosity of the flood and
thus lowers the mobility ratio.
This method has not been evaluated extensively for use in
environmental applications.
ASP Flooding
One combination of the techniques described above that has
undergone limited testing for environmental applications is
DEN/109R/002
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alkaline/surfactant/polymer (ASP) flooding. The addition of
an alkaline agent and a surfactant address IFT; the addition
of a polymer gives the flood a favorable mobility ratio. In
bench-scale tests, an ASP flood was highly effective in dis-
placing residual waste wood-preserving oil from a subsurface
sandy soil (Kuhn et al., 1988).
IN SITU SOIL-WASHING APPLICATIONS
Case Studies
The majority of the work conducted to date regarding enhanced
in situ recovery of oily subsurface contamination has focused
on the use of surfactants. Published work conducted by Amer-
ican Petroleum Institute (API) (1979 and 1985), The Ellis
(1984), and Tuck (1988) has demonstrated on a laboratory
scale that surfactant systems are effective in removing large
percentages of the residual oils present after waterflooding.
Briefly primary findings of these studies include:
o API (1979)—Residual oil saturation can be reduced
using surfactant flooding on a laboratory scale.
o API (1985)—Application of a surfactant to sandbox
scale-model aquifer underscored the difficulties
of optimally delivering the solutions to the oily
intervals.
o Ellis (1984)—Ninety percent cleanup levels using
surfactant systems support the need for field
demonstration.
o Tuck (1988)—The efficiency of in situ soil washing
can be enhanced using surfactants on a laboratory
scale.
The only published field demonstration of in situ oil washing,
known by the authors, was conducted at Volk Air Force base
in Wisconsin by the EPA (1987) . Results indicated no effective
recovery of residual oils in a field application despite
favorable results in the lab. The difference between lab
success and field failure at the Volks site is interpreted
as the difference in hydraulic flow conditions achieved in
the laboratory core flood versus the far less controlled
flow conditions in the field application.
A field soil washing pilot involving an ASP system is being
performed; however, no data on this test are availiable.
DEN/109R/002
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Potential Limitations
Additional issues pertinent to the potential of soil-washing
systems include: (1) compatibility of the soil-washing solu-
tion with the contaminated materials, aquifer skeleton, and
native formation water, and (2) the required level of effort
associated with treatment of the produced fluids.
Incompatibilities between the soil washing solution and the
subsurface materials can potentially result in negative
impacts. Chemicals used to enhance mobilities, such as alka-
line agents, can lead to the precipitation of inorganics,
such as calcium carbonate. If this happens on a large scale,
the inorganics can plug the formation, limiting the feasibil-
ity of further in situ remediations that rely on soil flushing.
Conversely, some proposed soil-washing systems could lead to
unfavorable leaching of trace metals. This condition could
result in trading organic contamination for inorganic contam-
ination. Still another issue is biological fouling of an
aquifer. Common components of soil washing systems are
readily biodegradable. If in situ biodegradation of the
soil washing system occurred extensively in the formation,
the pore space could be plugged with biomass.
Treatment of fluids withdrawn from the subsurface in the
in situ soil-washing process is also an issue. Surfactant-
based soil-washing systems tend to form oil-water emulsions
with the recovered oils. Separation into distinct phases
can be difficult, especially when the density differences
are small, as in the case of creosote-based wood-treating
oils and water. If the oils and aqueous fractions cannot be
isolated, then reuse of either the oil or the soil washing
solution will be difficult. Costly options, such as biolog-
ical treatment of produced fluids in an aboveground reactor,
may be required.
Conceptual Design of In Situ Soil-Washing Systems
Despite the lack of hard field data defining the feasibility
of surfactant-based in situ soil washing, the technology
does offer opportunities for remediation of subsurface mater-
ials contaminated with residual concentrations of oily wood-
treating wastes. Through in situ soil washing, the potential
exists to remove 80 percent or more of the residual oils,
thus reducing the contaminant source volume. In the case of
in situ bioreclamation, the benefit of such a reduction would
be a corresponding decrease in time and oxygen-demand require-
ments, a significant benefit for a potentially lengthy and
expensive remediation method.
Probable process components needed to implement an in situ,
soil-washing program include:
DEN/109R/002
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o Soil-Washing Solution Mixing. Except for small-
scale applications, mixing the soil-washing solu-
tions onsite will probably be cost-effective.
Facilities could include storage tanks, mixing
pumps, and filters capable of removing suspended
solids that could plug the formation.
o Subsurface Delivery System. An important aspect
of in situ soil washing is the effective delivery
of the soil-washing solution to the interval in
which the residual oil occurs. This delivery can
be accomplished through drainlines, wells, trenches,
or infiltration trenches. The most effective type
of delivery system will be a function of site-
specific conditions. In all cases, designs should
be developed to minimize plugging problems and to
allow for cleaning or redeveloping of the delivery
system.
o Fluid Recovery Systems. Equally important to effec-
tive delivery of the soil-washing solution to the
contaminated interval is recovery of the soil-washing
solution and the mobilized oil. Recovery systems
can include drainlines, wells, or trenches. Again,
the most effective system will be a function of
site-specific conditions. Selection of pumps for
the recovery systems should include recognition of
a need to minimize mechanical emulsion of produced
fluids and to handle a wide range of potential
flow rates.
o Produced Fluids Treatment. Fluids produced from
in situ soil washing will need to be treated to a
point where they can be reused or discharged without
detrimental environmental impacts. Since these
fluids are likely to contain emulsified oils, their
treatment may comprise a major component of the
soil-washing remediation effort.
Steps to Implementation
Due to the limited field experiences with in situ soil-washing
systems, applications will probably require a relatively
high level of preliminary evaluations. Where the potential
reduction of residual contamination justifies consideration
of in situ soil washing, the following factors should be
considered.
Attempts to develop generic surfactant-based soil-washing
solutions, both for petroleum and environmental applications,
have demonstrated that the types of systems that are success-
ful are a function of site-specific conditions, such as the
composition of the porous media, the quality of the water
DEN/109R/002
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that is present, and the composition of the oils. For
surfactant-based systems, evaluation of effective
soil-washing solutions should begin with laboratory
evaluations that use site-specific materials.
The types and concentrations of surfactants and viscosity
modifiers should be optimized with respect to the following
parameters:
o EOR—Interfacial tension and core-flood studies
can be run to select a system that is effective in
removing a maximum amount of residual oil at the
minimum reagent concentrations and cost.
o Treatability Studies—-Once a soil-washing solution
is selected, laboratory treatability tests should
be conducted to evaluate treatment/management strat-
egies and cost for produced fluids.
o Formation Plugging—During core floods, evaluation
of soil-washing solutions should include monitoring
of pressure drops across the cores through time to
identify potential plugging problems due to inorganic
precipitation, formation of stable emulsions within
the core flood, and/or biological activity.
o Inorganic Leaching—The potential for leaching of
inorganics can be evaluated by analyzing column
effluent or by conducting shaker-flask leaching
studies, using the proposed soil-washing solution
and site soils.
o Toxicity—Data regarding the toxicity of the soil
washing solution should be obtained.
Upon completion of the laboratory studies, a small-scale
field pilot test will probably be appropriate. Emphasis is
placed on the word "small" because laboratory data should
never be considered an absolute indicator of what will happen
in a field application. From a small-scale pilot, the issues
discussed for the laboratory studies can be evaluated in the
field, and sufficient data can be obtained for evaluation of
scaled-up applications.
SUMMARY
Cost-effective remediation of subsurface materials containing
waste wood-preserving oils poses a significant challenge.
In situ treatment or removal of these wa.stes is being con-
sidered with increasing interest. No "off the shelf" in situ
treatment/removal technologies effective in remediating these
sites are currently available. In light of this, evaluation
DEN/109R/002
19
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of means to remediate wood-treating sites requires review
and evaluation of innovative technologies. Recent research
and field¦applications have indicated that certain innova-
tive in situ removal techniques may be effective in cleanup
of subsurface materials containing waste wood-preserving
oil. No single in situ removal or treatment technique is
likely to be the most effective technique in all situations.
The most cost-effective in situ remediation approach at many
sites will likely consist of implementing two or more dif-
ferent techniques in sequence. Generalized ranges of contam-
inant concentration in which selected in situ removal/treatment
techniques will most likely be effective is graphically illus-
trated in Figure 5. Actual effectiveness and ranges of effec-
tiveness will, of course, depend on project-specific
considerations.
The most widely demonstrated and cost-effective of these
in situ removal techniques is waterflooding. Waterfloods,
when applied with the concept of managing the flow path along
which the oil migrates, can be highly effective in recovering
the mobile free-phase oils. This technique was demonstrated
by the case study of waterflood recovery presented in the
text. A primary benefit of waterflood recovery is the removal
of the mobile free-phase oil thereby, inhibiting further
migration of free-phase oils into uncontaminated areas.
Removal of this mobile free-phase oil using a waterflooding
technique will, in almost all circumstances, be the most
cost-effective first step in situ remediation.
A shortcoming of waterflooding is that a significant amount
of residual oil cannot be recovered. This residual oil can
act as a long-term source of dissolved contaminants. Thus,
the most promising application of waterfloods may be as an
in situ pretreatment step, with more costly in situ
treatment/removal techniques following to achieve lower
residual contaminant concentrations.
Several innovative in situ soil-flushing techniques appear
promising for achieving these lower residual contaminant
concentrations. Surfactant flooding seems to have the most
potential, and has been studied the most extensively. Sur-
factant flooding has been effective in bench-scale studies,
but little success has been demonstrated in field applica-
tion. However, it is an innovative technology in environ-
mental applications, and more success may be achieved after
further technological development. A key to achieving this
success may be more effective technology transfer from the
EOR industry.
Currently, waterflooding and other in situ soil-washing tech-
niques cannot be considered proven remediation techniques.
In general, development and testing of site-specific appli-
cations of these techniques are required before they can be
considered at a particular site for remediation of subsurface
DEN/109R/002
20
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IN SITU BIOREMEDIATION
V//////////////A
7////////////A
IN SITU SOIL WASHING
WATER FLOOD HYDROCARBON RECOVERY
DECONTAMINATED
ADSORBED
CONTAMINANTS
UP TO 10,000ppm
OR MORE
RESIDUAL OIL
HIGH CONTAMINANT LEVELS
25-10% OIL BY WEIGHT
APPROXIMATE
- HYDROCARBON -
CONCENTRATION
MOBIL, FREE
PHASE OIL
2*22*2
TECHNICALLY FEASIBLE RANGE
MOST COST- EFFECTIVE RANGE
FIGURE 5
MOST PROBABLE RANGE OF EFFECTIVENESS
FOR SELECTED IN SITU HYDROCARBON
REMEDIATION TECHNIQUES
-------
materials containing waste wood-preserving oils. These stud-
ies can be costly, but may be justified in the absence of
cost-effective site cleanup alternatives.
DEN/109R/002
22
-------
REFERENCES
1. Ellis, W.D., Payne, J.R., and McNabb, G.D., Treatment
of Contaminated Soild with Aqueous Surfactants,
EPA/600/2-85/129, U.S. Environmental Protection Agency,
Cincinnati, Ohio. 1985.
2. Ellis, W.D., Payne, J.R. Tafuri, A.N., and Freestone,
F.J., "The Development of Chemical Countermeasures for
Hazardous Waste Contaminated Soil," Proceedings of 1984
Hazardous Material Spills Conference. Washington, D.C.
1984 .
3. Hazardous Materials Technical Center, Installation Resto-
ration Program Records Search prepared for 8204th Field
Training Site, Wisconsin Air National Guard, Volk Field,
Camp Douglas, Wisconsin, August 1984.
4. Mason & Hanger-Silas Mason Col, Inc., Field Study of
the Fire Training Area, Volk Field ANG Draft REport,
July 17, 1985 to EPA Releases Control Branch. (Internal
Report to EPA)
5. Mason & Hanger-Silas Mason Co., Inc. Volk Field Contam-
inated Groundwater Bench Scale Treatability Studies,
September 1985. Draft report. November 1985 to EPA
Releases Control Branch.
6. McNab, G.D., et al., Chemical Countermeasure Application
at Volk Field Site of Opportunity. EPA report Septem-
ber 19, 19 85. (Internal report to EPA)
7. Salager, J. L., J. C. Morgan, R. S. Schechter, W. H. Wade,
and E. Vasquex. Optimum Formulation of Surfactant/Water/
Oil Systems for Minimum Interfacial Tension or Phase
Behavior. Society of Petroleum Engineers Journal.
1979. Pp. 107-115.
8. Sale, Tom C., Dave Stieb J., Keith R. Piontek, and Bob C.
Kuhn. "Recovery of Wood-Treating Oil from an Alluvial
Aquifer Using Dual Drainlines." Proceedings of Petroleum
Hydrocarbons and Organic Chemicals in Ground Water,
National Water Well Association. Worthington, Ohio.
1988. Pp. 419-422.
9. Texas Research Institute, Inc. "Test Resutls of Surfactant
Enhanced Gasoline Recovery in a Large-Scale Model Aquifer,"
American Petroleum Institute, Washington, D.V., API
Publication 4390. April (1985).
DEN/40W/031.1
-------
10. Texas Research Institute, Inc., 1979. Underground Move-
ment of Gasoline on Groundwater and Enhanced Recovery
by Surfactants. American Petroleum Institute, Washington,
D.C.
11. Tuck, David M., Peter R. Jaffe, David A. Crerar, and
Robert T. Mueller. "Enhanced Recovery of Immobile
Residual Non-Wetting Hydrocarbons from the Unsaturated
Zone Using Surfactant Solutions." Proceedings of
Petroleum Hydrocarbons and Organic Chemicals in Ground
Water, National Water Well Association. Worthington,
Ohio. 1988. Pp. 457-479.
12. Villaume, James F. "Investigations at Site Contaminated
with Dense, Non-Aqueous Phase Liquids (NAPLs)." Ground
Water Monitoring Review. Pp. 60-74. Spring 1985.
13. Villaume, James F., Philip C. Lowe, and Dennis F. Unites.
Recovery of Coal Gasification Wastes: An Innovative
Approach. Proceedings of the Third National Symposium
on Aquifer Restoration and Ground Water Monitoring,
National Water Well Association. Worthington, Ohio.
1983. Pp. 434-445.
14. Wisniewsky, G. M., G. P. Lennon, J. F. Villaume, and
C. L. Young. Response of a Dense Fluid Under Pumping
Stress. Proceedings of the 17th Mid-Atlantic Indus.
Waste Conf. Lehigh University. Bethlehem, Pennsylvania.
1985. Pp. 226-237.
DEN/40W/0 31.2
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PHYSICAL SEPARATION FOR EXCAVATED SOILS
AND
IN-SITU VACUUM EXTRACTION
Frank J. Freestone, EPA-ORD, Edison, New Jersey
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EPA R&D PROGRAM ON TREATMENT OF EXCAVATED
SOILS, SLUDGES AND SEDIMENTS
Frank J. Freestone
Chief, Technology Evaluation Section
Releases Control Branch (Edison, NJ)
Superfund Technology Demonstration Division
Risk Reduction Engineering Laboratory, Cincinnati, OH
BACKGROUND
The Superfund research and development program that has been conducted
at Edison, NJ has, since the inception of Superfund, been focused on the
development and demonstration of mobile technologies for cleanup of waste
sites. During the middle and late 1970's several prototypical mobile systems
were developed by other EPA research programs that were focused on cleanup of
spills of oils and hazardous materials, including a mobile incineration
system, a mobile soils washing system, a mobile water treatment system and
other systems for on-site cleanup. The intention of the development and
demonstration of these prototypes has been to influence the private sector to
develop similar, better systems based upon the government-sponsored research,
and to make those systems available to EPA, the states, and private companies
for contract cleanups.
Thus far, the program has been highly successful, particularly with the
influence of mobile incineration and mobile water treatment technologies.
Now, these technologies are widely available commercially after the first
field uses of such systems were undertaken and publicized by EPA.
PROGRAM GOAL
The current thrust of the Superfund R&D being undertaken at Edison, NJ
is to influence and encourage commercial development and utilization of
viable systems for on-site treatment of soils, sludges, and sediments at
Superfund and other remediation sites. In particular, extraction of con-
taminants using water with or without additives and other extraction fluids
in liquid or gaseous states, is being pursued toward achieving volume re-
duction as a treatment concept.
1
-------
DEFINITIONS
Volume reduction for excavated materials is a multi-step treatment
process that separates the contaminated solids into two fractions: a larger
sized fraction consisting of cleaned soils and other solids that have a small
enough measurable residual contaminant present that they can be returned to
the original excavation or can otherwise be treated as nonhazardous mate-
rials, and a smaller sized fraction consisting of concentrated contaminant
typically contained in a fluid or sludge. This concentrated contaminant must
be subjected to further treatment or disposal techniques for the cleanup to
be complete.
PROGRAM DESIGN
The program is divided into five major areas of activity:
0 Characterization of the problems.
° Evaluation of the current state-of-art.
0 Development and demonstration of promising, viable systems.
0 Technology transfer to EPA client offices and the private sector.
° Coordination with other organizations performing similar work.
Characterization of the Problems
Extraction of contaminants from excavated soils, sludges, and sediments
is a technology areas that encompasses a wide variety of specific problem
types and potential technical approaches. No single system or approach now
commercially available or currently under development will successfully
separate all known contaminants from all known site situations. Evaluation
of the performance of existing technologies and the development of new ones
should ideally be accomplished according to a priority scheme that takes into
account the technical tractability of problems and their frequency of occur-
rence. Further, treatability testing protocols, are needed to evaluate the
expected performance of candidate cleanup technologies. Therefore, it is
necessary to analyze these problem types with respect to the general capa-
bilities of available technologies and develop problem characterization
approaches.
2
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Three key sets of information needed are the distinction of repetitive
situations from unique ones, the distinction of relatively simple situations
for relatively complex ones, and the determination of the numbers of sites or
volumes of materials that are associated with the most highly repetitive
situations, both simple and complex. For example, from a technological
viewpoint, highly volatile organics are treatable by different approaches
than semi-volatiles or nonvolatiles; metals and' inorganics may require dif-
ferent approaches than those used for organics. Combinations of metals and
organics may require sequential treatment in ways that are more complex than
if organics alone were present. Radioactive contaminants, a specialized
subset of metals contamination, may require treatment techniques related to
those used for metals but having certain unique characteristics.
Once these sets of information are developed and organized, and using
information regarding the current commercial state-of-the-art, priority
decisions can be made regarding expenditure of funds for the purpose of
developing technologies. Such developments are most likely to succeed if
aimed first at the highest frequency of occurrence, simplest to solve pro-
blems, and secondarily aimed at problems having either greater complexity or
lower frequencies of occurrence or both.
One characterization scheme is to divide sites up by the industries that
contributed the wastes. This approach is particularly useful for single
industry sites such as underground storage tanks for fuels, wood treating
sites, lead battery reclaimer sites, and sites having radioactive contamina-
tion from various man made sources. Some data on sites of these types are
available through OERR.
An alternate characterization approach is to group sites according to
the type of contaminant present (e.g., organics, metals, radioactive) or the
nature of the soils (e.g., relative percentages of sands, silts, clays, and
humic materials).
A major activity related to characterization has been the development of
standard soils matrices ("SSM") for use in comparing the performance of soils
treatment technologies at bench- and pilot-scales. These matrices consist of
reproducible blends of specially selected soils and chemicals to simulate
Superfund site soils. The matrices are currently in use in support of the
SITE program to assist in demonstrations of new soils treatment systems.
3
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Example projects currently ongoing or planned in this technology area
i nclude:
° Development of standardized soil and contaminant combinations for
evaluating soils treatment systems.
0 Development of a mobile soils treatability laboratory.
0 Development of treatability testing protocols for contaminant
extraction technologies for soils.
Evaluation of the Current State-of-the-Art
In order to advance the state-of-the-art, it is obviously necessary to
understand the capabilities of existing technologies, available in the U.S.
and internationally. We must be aware of technologies that are currently
available fur use at waste sites as well as those available through related
industries, such as the chemical process, food and mining industries. Fur-
ther, as new techniques are developed commercially, it is necessary to
evaluate their performance for the specific situations for which they were
designed, and to obtain objective performance data of known quality. The
program has developed state-of-the-art studies, and will take advantage of
the SITE program at full-scale and at pilot-scale to provide needed data.
Further, the program will support treatability studies jointly with OSWER to
obtain needed performance data for site-specific problems.
Example projects currently ongoing or planned in this technology area
include:
° Report: "Technological Approaches to Cleanup of Radiologically
Contaminated Superfund Sites".
° Interim Draft Report: "Assessment of Technologies for the Re-
mediation of Radioactively Contaminated Superfund Sites".
0 Draft Report: "Cleaning Contaminated Excavated Soil Using Extrac-
tion Agents".
° Participation in OSWER's "Engineering Forum" for treatability
studies on site-specific problems.
° Participation in the SITE program relative to evaluation of com-
mercial full-scale and pilot-scale (Emerging Program) systems.
4
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Development and Demonstration of Promising, Viable Systems
Once the problem types are understood, and the existing commercial
technologies are understood, a development and demonstration program can be
designed. The development and demonstration portions of the program are
intended to identify and develop new, viable approaches at bench- and pilot-
scales and to demonstrate the pilot-scale systems at Superfund sites. In-
cluded in the program are technologies to control dusts and vapors from
excavations, and techniques to handle debris and other feed problems.
A mobile treatability system is being constructed as the overall goal of
the program area on "Development and Demonstration". This capability will
consist of a mobile laboratory in which to perform bench-scale studies and
other support of on-site treatability tests, and a set of interconnected
semi-traflers on which will be mounted pilot-scale versions of numerous soils
washing systems. When complete, the mobile system will be useable for pilot-
scale testing at Superfund sites to assist in resolving site-specific prob-
lems.
Example projects currently ongoing or planned in this technology area
include:
0 Control of dusts and vapors released during excavation.
0 Treatment of recovered vapors with encapsulating foams.
° Identification of feedstock preparation and debris handling
technologies.
° Identification of interrelationships between contaminants and soil
particles.
° Development of a sequenced batch reactor for microbial mineraliza-
tion of excavated soils.
0 Development of vacuum-assisted steam strippino system for treatment
of excavated soils.
0 Development of a pilot system for extraction of semi-volatile
organics using ultrasonic contacting..
0 Development of a pilot system for extraction of lead and other
heavy metals from excavated soils.
5
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° Preparation of a pilot-scale trommel washer system for particle
size separation/volume reduction treatment of excavated soils.
° Development of a sonic-frequency extraction system for semi-
volatile contaminants on excavated soils.
Technology Transfer to EPA Client Offices and the Private Sector
Given the stated program goal of influencing the private sector to
utilize promising technologies on tractable problems, the transfer of in-
formation developed under this program at public expense takes a high
priority. There are four activities ongoing within this program area to
accomplish technology transfer: Use of the Federal Technology Transfer Act
(FTTA); conducting technical support efforts for regional site-specific
problems, developing and maintaining information exchange systems, and con-
ducting information exchange meetings.
Under the FTTA, a soils washing system previously developed by ORD will
be transferred for use by a private company interested in using the system
for site cleanup activities. The system consists of a trommel washer and a
froth flotation cell modified into a four cell countercurrent chemical ex-
tractor. Additional efforts will likely be conducted in the future to utilize
this broad-based FTTA authority to enhance information interchange between
EPA and companies interested in using advanced technologies for site clean-
ups.
As noted above, technical support efforts are conducted to help solve
site specific Regional needs, predominantly in the form of participation in
the "Engineering Forum". Many of these efforts have involved laboratory
scale treatability studies to determine the potential performance of particle
size separation for volume reduction. Future efforts will include use of the
mobile pilot-scale soils treatment system f.or on-site treatability studies.
Additional technical support efforts include a Technical Information
Exchange to provide printed and computerized information regarding ongoing
programs and technologies at Edison, NJ.
A seminar on extraction of contaminants from excavated soils was held in
Edison, NJ with vendors and other interested parties in early December, 1988
and with a synopsis of that meeting will be made available by Summer, 1989.
6
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Coordination With Other Organizations Performing Similar Work
This program area does not have currently defined projects, however, as
treatment of excavated soils becomes a more accepted technology and as a
greater number of vendors become interested in providing hardware or ser-
vices, a greater number of organizations will become interested in the tech-
nology area. To be successful, our program must maintain coordination with
those organizations to avoid duplication of effort and to encourage infor-
mation exchange.
For more information about the program in general or the status of
specific projects, contact Richard Traver, Program Manager, at FTS 340-6677
or (201) 321-6677. For information regarding radiological problems, contact
Darlene Williams at FTS 340-6925 or (201) 906-6925. For information re-
garding the Technical Information Exchange and the associated Computerized
On-Line Information System (C0LIS), contact Hugh Masters at FTS 340-6678 or
(201) 321-6678. For information regarding SITE projects pertaining to ex-
tractive technologies, contact Mary Stinson at FTS 340-6683 or (201)
321-6683.
7
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GROUNDWATER CONTAMINANTS AT WOOD TREATMENT FACILITIES
Jeffrey K. Rosenfeld, EPA-EMSL, Las Vegas, Nevada
(Lockheed Engineering)
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GROUND-WATER CONTAMINANTS AT WOOD TREATMENT FACILITIES
Jeffrey K. Rosenfeld and Russell H- Plumb Jr., Lockheed Engineering
& Sciences Company, Las Vegas, Nevada 89119.
Ground-water contamination at five wood treatment facilities
across the country have been compared. The distributions of
organic priority pollutants at the five sites are similar with the
most common contaminants being polynuclear aromatic hydrocarbons
and phenolic compounds. These contaminants are the predominant
constituents of creosote and their relative concentrations in
ground water are controlled by solubility, adsorption, and
biodegradation. The distributions of the organic priority
pollutants at the five sites are different than those at an
"average" hazardous waste site and specific recommendations for
monitoring wood treatment facilities will be made. Inorganic
contaminants have also been detected at these sites, but their
distributions are not uniform across all the sites.
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GROUND-WATER CONTAMINANTS AT WOOD TREATMENT FACILITIES
Jeffrey K. Rosenfeld and Russell H. Plumb Jr. , Lockheed Engineering
& Sciences Company, Las Vegas, Nevada 89119.
ABSTRACT
Ground-water contamination at five wood treatment facilities
across the country has been compared. The distributions of organic
priority pollutants at the five sites are similar, with the most
common contaminants being polynuclear aromatic hydrocarbons and
phenolic compounds. These contaminants are the predominant
constituents of creosote and their observed concentrations in
ground water appear to be controlled by solubility, adsorption, and
biodegradation. The distributions of the organic priority
pollutants at the five sites are different than those at an
"average" hazardous waste site and specific recommendations for
monitoring wood treatment facilities are made. Inorganic
contaminants have also been detected at these sites, but their
distributions are not uniform across all sites.
INTRODUCTION
Ground-water contamination at wood treatment facilities is a
serious environmental problem with over 40 wood sites currently on
the U.S. Environmental Protection Agency National Priorities
(••Superfund") List. In addition, as a result of the permitting
requirements of the Resource Conservation and Recovery Act, ground-
water monitoring is occurring at numerous other wood treatment
sites. The purpose of this study is to characterize the ground-
water contamination at several of these sites in order to determine
if there is a consistent "chemical fingerprint" for the wood
treatment industry. In this way, a set of ground-water monitoring
parameters can be customized for the industry and this fingerprint
could potentially be used to pinpoint the source of contamination
identified during a regional investigation.
This study used ground-water data from five wood treatment
sites across the country. These sites are located in Arkansas,
Georgia, Idaho, Mississippi, and Texas. They were chosen because
of the availability of complete ground-water chemical data
including organic priority pollutants, metals, and water quality
measurements. The facilities appear to have used creosote as the
primary wood preservative, but pentachlordphenol and metal arsenate
were also used. The distribution of chemicals detected in the
ground water at these sites and their average concentration are
discussed below. In addition, a suggested approach for monitoring
wood treatment facilities, based on the findings of this study, is
presented at the end of the paper.
-------
RESULTS
Organic Constituents
The results for the 126 Target Compound List compounds are
shown in Figures 1 through 4. The Target Compound List (Table 1)
is the list of organic compounds specified by the EPA in the
Contract Laboratory Program and includes the volatiles, semi-
volatiles, PCBs, and pesticides normally analyzed by EPA methods
624, 625, and 608. The top graph in each of the figures shows the
percentage of samples in which the compound was detected at each
site and the lower graph shows the average concentration. The
frequency of detection for each compound is generally less than 50%
at each of the sites, because at least half of the samples taken
at each site were taken from non-contaminated wells. The average
concentration shown is the mean of the concentrations in the wells
where the compound was actually detected. In this way, the average
concentration was not affected by the number of clean wells sampled
at the site.
The first 34 compounds in the Target Compound List are the
volatile organic compounds. Figure 1 summarizes the volatile
results at the 5 wood treatment facilities, as well as an industry
average for the 5 sites. The first thing to notice is the
consistency of the results. If a compound was detected at one
site, then most likely it was also found at other sites as well.
A large number of the volatile compounds were not detected at any
of the sites.
The volatile compounds detected at most of the sites include
benzene (#23), toluene (#29), ethylbenzene (#32), and xylene (#34).
These are all simple aromatic hydrocarbons commonly detected in
fuels. They are most likely present in the ground water, as a
result of either being in the low distillation end of the creosote
itself, or in the carrier used for the creosote, or possibly as
degradation products from the more complex aromatic hydrocarbons
found in creosote.
The most commonly detected volatile organic compounds are
methylene chloride (#5) and acetone (#6). These are common
laboratory contaminants, found not only in the contaminated
samples, but also the "clean" samples and the blanks at the
different sites.
The lower half of Figure 1 presents the average concentration
data for the volatile organic compounds. The major ground-water
contaminants, benzene, toluene, ethylbenzene, and xylene, are
present in the 5-300 ppb range. The laboratory contaminants,
methylene chloride and acetone, have relatively low concentrations
(<50 ppb) typical of a laboratory contamination problem.
-------
There are 65 semi-volatile compounds on the Target Compound
List. Figure 2 summarizes the monitoring data for the first 33
compounds. The compounds commonly detected at the wood treatment
facilities include phenol (#35), 2-methylphenol (#42), 4-
methylphenol (#44), 2,4-dimethylphenol (#50), naphthalene (#55),
2-methylnaphthalene (#59), and acenaphthylene (#66). The first
four are phenolic compounds and the last three are polynuclear
aromatic hydrocarbons (PAH). These two compound types are the
predominant constituents of creosote. Creosote is a very complex
mixture of organic compounds whose exact composition depends on the
coal tar from which it is produced. It generally contains about
85% PAH and from 2-17% phenolic compounds (Ehrlich, et al.,1982).
The PAH and phenolic compounds, with the exception of
acenaphthylene, are not only commonly present, but also occur at
fairly high concentrations ranging from 500-11,000 ppb.
Figure 3 shows the frequency of detection data for the
remaining half of the 65 semi-volatile compounds. The commonly
occurring compounds include the following PAH compounds:
acenaphthene (#69), fluorene (#76), phenanthrene (#83), anthracene
(#84), fluoranthene (#86), pyrene (#87), benz(a)anthracene (#90),
chrysene(#91), benzo(b)fluoranthene (#94), benzo(k)fluoranthene
(#95), benzo(a)pyrene (#96) and indeno(123-cd)pyrene (#97). These
are again fairly common constituents of creosote.
Other semi-volatiles commonly detected include dibenzofuran
(#72), which is a constituent of creosote, and bis(2-ethylhexyl)
phthalate (#92), which is a laboratory contaminant commonly found
in blanks, clean, and contaminated samples. A surprising result
was the lack of pentachlorophenol (PCP-#82) contamination. Most
likely, this is because these sites have predominantly used
creosote for preservation rather than PCP. The Texas facility had
used PCP, but discontinued its use in 1962. It may be that PCP was
never in the ground water at the Texas site or if it was, the PCP
has been biodegraded in the 25+ years since its use. PCP can be
a major ground-water contaminant. Ground-water concentrations from
a PCP site (not included in this study because of only partial
analytical results) ranged from 1 ppb to more than 100 ppm.
The average concentrations for the semi-volatile compounds in
Figure 3 are lower than for the first group of semi-volatiles
(Figure 2), but are still generally in the 200-5,000 ppb range.
Pesticides and PCBs were generally not detected in the ground
water beneath the five wood treatment sites (Figure 4). The peak
at #125 is from one sample at one site containing 3 ppb of PCB-
1254. The lack of pesticide contamination was somewhat surprising
in view of the amount of wood that was stored at these sites. It
suggests that additional pesticides, other than creosote, may not
have been used for pest control at the sites.
-------
In summary, only 27 of the 126 Target Compound List compounds
were commonly detected in the ground water at the 5 wood treatment
sites. Six were volatile compounds and the other 21 semi-
volatiles. Of the total, three compounds were most likely the
result of laboratory contamination rather than wood preserving.
The remarkable thing about these results is the consistency of
compound detection. If a compound was present at one site, then
it was most likely present at several of the other sites. The
ground-water monitoring results suggest a fairly strong industry-
specific chemical fingerprint, due to the consistent detection of
the commonly occurring compounds and the large number of Target
Compound List compounds that were not detected at the sites.
The organic constituents results are summarized in Tables 2
and 3. Table 2 shows the industry average for the 25 most common
compounds ranked by frequency of detection. The polynuclear
aromatic hydrocarbons are the predominant compound type in the
ground water. The PAH compounds are shown with their carbon number
- the higher the carbon number, the more complex the compound. For
example, naphthalene at CIO is made up of two fused benzene rings,
while benzo(a)pyrene at C20 has 5 fused benzene rings. More
importantly, the solubility of the PAH compounds decrease with
increasing carbon number. Naphthalene, with a solubility of 34
mg/1, is nearly 10,000 times more soluble than benzo(a)pyrene. In
addition, the higher carbon number PAH compounds are more strongly
adsorbed onto the organic carbon in soils than the less complex PAH
compounds. Benzo(a)pyrene is over 500 times more strongly adsorbed
than naphthalene from a comparison of their octanol/water partition
coefficients (Ekambaram, 1986).
The frequency of detection data show that the smaller carbon
number PAH compounds are more commonly detected in ground water
than the more complex ones. This makes sense in that they are more
soluble and less strongly adsorbed, and therefore more mobile. The
two volatile laboratory contaminants, acetone and methylene
chloride, are the two most commonly detected compounds. The
volatile aromatic compounds, benzene, toluene, ethylbenzene, and
xylene are also among the top 25 compounds.
Table 3 shows the industry average ranked by average
concentration. Four of the six compounds with the highest average
concentration are phenolic compounds. This can be explained by
their much higher solubilities compared to the PAH compounds,
despite their much lower concentrations in creosote. For example,
naphthalene, the most soluble PAH and the most common constituent
in creosote, is approximately 2000 times less soluble than phenol.
The PAH compounds generally show decreasing average concentration
with increasing carbon number. This is in keeping with the more
complex PAH compounds being less mobile (lower solubility and
higher adsorption) and also being less abundant in creosote than
the simpler ones.
-------
A sample at the Idaho site supplied additional information on
the issue of mobility of the different chemicals in creosote.
Creosote was encountered in the saturated zone while drilling, and
a sample was taken of the creosote-contaminated water which seeped
into the borehole. Table 4 shows the comparison of the chemical
composition of the creosote-contaminated water and the ground water
at the site.
The major constituents are PAH compounds and phenols with some
concentrations in excess of one million ppb. These are the major
components of creosote and these levels are above the solubility
of these compounds suggesting more of a water/creosote mixture,
rather than only a water sample. Naphthalene is the most abundant
chemical present in the waste sample, which is consistent with it
being the most abundant chemical in creosote and the most soluble
PAH. The concentrations of the PAH compounds generally decrease
with increasing carbon number, which agrees with the composition
of creosote, the decreased solubility, and the increased adsorption
of the more complex PAH compounds.
Table 4 also contains the average ground water concentrations
at the Idaho site in order to compare the relative mobility of the
different chemicals. The chemicals detected in ground water more
or less follow the same concentration trend as seen in the waste
sample. This suggests that the predominant control on the
concentration is the chemistry of the source material. However,
the ratio of the concentrations in the waste sample and the average
ground water suggest that there are other controls on mobility..
The ratios for the PAH compounds range from about 2,000 for
naphthalene (CIO) to almost 19,000 for benzo(a)pyrene (C20). This
agrees with the general trend that the more complex PAH compounds
are not as mobile as the simpler ones. The phenols, which are all
more soluble than the PAH compounds, have lower ratios which
suggest that they are more mobile.
Mobility is controlled not only by solubility and adsorption,
but also by chemical reaction and biodegradation, which can result
in either the destruction or production of certain chemicals. The
production of simpler PAH compounds is suggested by this Idaho
sample, in which anthracene, acenaphthylene, and fluorene were not
detected in the waste sample (granted at a high detection limit),
but were detected in the ground water.
Inorganic Constituents
Ground water samples at the sites were also analyzed for
metals and other inorganic constituents.' The inorganic results
were compared in order to determine if there was a consistent
inorganic fingeirprint at the sites, as was observed for the organic
priority pollutants. Possible metals to consider include arsenic,
chromium, and copper, because of the use of chromated copper
arsenate as a wood preserver.
-------
Inorganic contamination must be dealt with differently than
organic contamination, because the inorganics are commonly
naturally occurring. Therefore, background values must be
determined and compared with the sample results. In this study,
the wells which did not show any organic contamination were chosen
to be the background wells and compared with the wells which did
show organic contamination.
Inorganic constituents, in which the ratio of the average
contaminated concentration for the site to the background
concentration was greater than 3, were used as indicators of
contamination. The value of 3 (or a 300% increase in
concentration) was chosen arbitrarily, in order to reduce some of
the noise created by using total metal concentrations rather than
dissolved concentrations. Each site seemed to have a number of
samples (both contaminated and clean), in which all the
concentrations (especially iron, lead and aluminum) are much higher
than for the other samples. These values are most likely the
result of samples containing high concentrations of suspended
material, rather than inorganic indicators of contamination.
Figure 5 shows the number of sites at which individual
parameters exceeded the contaminated/clean ratio of 3. Of the
thirteen parameters shown, only manganese suggests any indication
of contamination at more than three sites. Therefore, unlike the
organic results, there do not appear to be any clear inorganic
indicators of contamination for wood treatment facilities. The
increased concentration of manganese is not easily explained, since
manganese does not appear to be used in the wood preserving
process. Manganese is more soluble under reducing conditions
(Stumm and Morgan, 1970), and the increase in concentration may be
a consequence of the ground water becoming anoxic due to the
abundant organic contamination. It was surprising that arsenic,
chromium, and copper did not show up more often, but this may be
due to the fact that these facilities used predominantly creosote
in their operations.
Comparison with "average" hazardous waste site
Previous studies at EMSL-Las Vegas have examined the
distribution of organic priority pollutants at over 100 hazardous
waste sites (Plumb and Pitchford, 1985). These studies have
pointed out the importance of monitoring for volatile organic
compounds and showed that they accounted for over 75% of the
organic compounds detected at hazardous waste sites. It was also
shown that the number of volatile compounds detected could be
correlated with the number of priority pollutants detected and that
by measuring only the volatiles, one could predict the number of
priority pollutants that would be detected at a site.
-------
The wood treatment facilities appear to differ from most
hazardous waste sites, because of the nature of the chemicals used
for wood preserving. Creosote consists predominantly of semi-
volatile polynuclear aromatic hydrocarbons and phenolic compounds.
These semi-volatile compounds were also the principal ground-water
contaminants detected at the wood treatment sites. Therefore, the
approach of just monitoring for volatile compounds, in order to
predict the need for more extensive characterization of the ground-
water samples, would not really work at these facilities.
Figures 6 through 9 show the Target Compound List compounds
detected at the average hazardous waste site compared to the
industry average for these 5 wood treatment facilities. The
volatiles (Figure 6) show a wider variety of compounds detected at
the hazardous waste sites compared to the wood sites. The
predominant volatile compounds at the average hazardous waste site
include the chlorinated compounds, such as trichloroethene,
perchloroethene, and dichloroethene. These compounds were not
detected at the wood sites. The semi-volatile compounds (Figures
7 & 8) are relatively unimportant at the average hazardous waste
site. However, as shown previously, they are the predominant
ground-water contaminants at the wood sites. Pesticides (Figure
9) have been observed to be more abundant at the average hazardous
waste site than at the wood treatment facilities.
SUMMARY
In summary, this study has demonstrated the predominance and
consistency of semi-volatile organic contamination of ground water
at creosote wood treatment facilities. It must be stressed that
the study dealt mainly with creosote facilities. If data had
instead been received from a group of arsenate facilities, this
study would have had a different emphasis. So in developing a
monitoring strategy for a wood facility, it is important to know
what process the facility used.
In terms of monitoring parameters for wood treatment
facilities, the semi-volatile compounds should be emphasized. This
should be effective for both creosote and PCP facilities. If the
facility used an arsenate process, then metals analyses should be
routinely incorporated into the monitoring program. During an
initial site investigation, at least some of the samples should be
analyzed for all priority pollutants and metals, because of the
possibility of multiple wood treatment processes at the same site.
Monitoring results for volatile compounds could be important,
because these compounds are more mobile than the semi-volatiles and
could be in a separate plume. One of the surprises of this study
is that the volatiles and semi-volatiles occurred in the same wells
and were not separated by their different mobilities.
Teflon or stainless steel well casing are recommended for site
investigations at wood treatment facilities. PVC should not be
used, because of the possibility that it could interact with and/or
be degraded by the organic compounds.
-------
Since the semi-volatiles are the predominant type of organic
compound present, the type of sampler used is not as critical as
if the contamination at wood treatment facilities were
predominantly volatile compounds. Sampling at the top of the water
table to collect both water and floaters is recommended. PCP is
used with a solvent and is commonly found with the floaters.
Creosote, on the other hand, is a sinker and therefore, sampling
at the bottom of the aquifer may also be necessary.
Since the polynuclear aromatic hydrocarbons are strongly
adsorbed onto the soil and not volatile, collecting soil samples
and sending them to the laboratory for semi-volatile analysis is
recommended for determining extent of soil contamination, rather
than attempting a soil gas survey.
ACKNOWLEDGMENT
This work was conducted under Task Directives 4DMO2 and 89G01
of Contract 68-03-3245 between the U.S. Environmental Protection
Agency, Environmental Monitoring Systems Laboratory, Las Vegas,
Nevada, and Lockheed Engineering & Sciences Company, Las Vegas,
Nevada. The EPA Technical Monitor is Steven P. Gardner.
NOTICE
Although the research described in this document has been
funded wholly or in part by the United States Environmental
Protection Agency, it has not been subjected to Agency review and
therefore does not necessarily reflect the views of the Agency and
no official endorsement should be inferred.
-------
REFERENCES
Ehrlich, G.G., Goerlitz, D.F., Godsy, E.M. and Hult, M.F., 1982,
Degradation of Phenolic Contaminants in Ground Water by Anaerobic
Bacteria: St. Louis Park, Minnesota: Ground Water, v. 20, p. 703-
710.
Ekambaram, Vanavan, 1986, Geochemical Behavior of Contaminants from
Wood-Preserving Operations: Proceedings of Haztech '86
International Conference, August 11-15, 1986, Denver, Colorado, p.
246-261.
Plumb, R.H., Jr. and Pitchford, A.M., 1985, Volatile Organic Scans:
Implications for Ground Water Monitoring: Proceedings of NWWA/API
Conference on Petroleum Hydrocarbons and Organic Chemicals in
Ground Water - Prevention, Detection and Restoration, November 13-
15, 1985, Houston, Texas, p. 207-222.
Stumm, W. and Morgan, J.J., 1970, Aquatic Chemistry: New York,
Wiley-Interscience, 583 p.
-------
o
\a
a
o
o
o
at
100%
WOOD TREATMENT FACILITIES
VOLATLES - PERCENT DETECT
MS
T ^T— — m—»—^ w w * ¥ ™ *——W W * T T ™ 1 TT *r¦» *
1 2 3 4 56 76 9 10111213141516171819 20 21 22 23 24 25 26 27 2B 29 30 31 323334
E> v INO. AVE.
AR
TARGET COMPOUND UST
GA a TX x
<
pt
o
8
<
e
>
340
320
300
280
260
240
220
200
180
160
MO
120
100
80
60
40 -
20 -
0
WOOD TREATMENT FACILITIES
V0LAT1ES - AVERAGE CONCCKTRATKM
¦ ¦¦¦¦¦
¦ p WU'i)!
2 3 4 5 6 7 8 9 10 II 12 13 14 IS 16 17 18 19 20 21 2223 24 2526 27 28 2930 31 323334
MS
AR
GA
TARGET COMPOUND LIST
AT X x
MD. AVE.
Figure 1. Frequency of detection and average concentration for volatile
organic compounds at wood treatment facilities.
-------
WOOD TREATMENT FACILITIES
SEMHVOLATILES - PERCENT DETECT
W ¦ •
3S 36 37 36 38 4© 41 42 43 44 45 46 47 46 48 SO 51 52 59 S4 66 56 57 56 5960 61 626364 656667
MS
AR
TARGET COMPOUND UST
OA a TX x
IND. AVE.
WOOD TREATMENT FACILITIES
SEMHVOLATtfS - AVERAGE CONCENTRATION
35363736 99 40 41 42 43 44 45 46 47 46 40 SO 51 62 53 54 88 5657 58 6960 61 626364656567
MS
AR
TARGET COMPOUND UST
OA A TX x
WD. AVE.
Figure 2. Frequency of detection and average concentration for semi-volatile
organic compounds at wood treatment facilities.
-------
ioo%
WOOD TREATMENT FACILITIES
SEMt-VOLATILES - PERCENT DETECT
MS
67 68 6S 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 8687 888990 91 9293 94 95 96 97 98 99
TARGET COMPOUND LIST
* AR o GA a TX x K> ? IND. AVE.
MS
WOOD TREATMENT FACILITIES
SEMHVOLATIES - AVERAGE CONCENTRATION
II -
10 -
9
8 -
7 -
6 -
5 -
4 -
3 -
2
1 -
m m m m
67 68 69 70 71 72 73 74 75 76 7778 7980 81 8283 84858687 88 89 90 91 929394 9596 9798 99
AR
GA
TARGET COMPOUND UST
& TX x
K>
IND. AVE.
Figure 3. Frequency of detection and average concentration for semi-volatile
organic compounds at wood treatment facilities.
-------
100%
WOOD TREATMENT FACILITIES
PESTICIDES - PERCENT DETECT
90%
1
BOX -
70% -
60% -
50% -
40%
3QX -
20X -
10% -
0%
MS
100 101 102103104105106107106109 1)0 111 112 113 114 HS 116 117 116 118 120 121 122 123 124 125 B6
TARGET COMPOUND UST
¦+• AR o GA a TX x K> ? IND.AVE.
WOOD TREATMENT FACILITIES
PESTICIDES - AVERAGE CONCENTRATION
MS
100 101102103104105106107106109 HO 111 112113 114 115116117116119120121122129124 125126
TARGET COMPOUND UST
*¦ AR o GA a TX x D v IHD. AVE.
Figure 4. Frequency of detection and average concentration for pesticides
and PCBs at wood treatment facilities.
-------
w
&
fi
MONITORING PARAMETERS
CONTAMMATED/CLEAN RATIO > 3
PARAMETER
IZZ) MS [S3 AR VZZA GA ESS3 TX KZ1 »
Figure 5. Inorganic monitoring parameters with contaminated/clean concentration ratios greater than 3.
-------
100%
WOOD VERSUS HAZARDOUS WASTE SITES
VOLATLES - PERCENT DETECT
1 2 3 4 5 6 7 8 9 101112131415161716 19 20 2122 2324 25 2627282930 3132 33 34
~ WOOD TREATMENT
TARGET COMPOUND LIST
+ HAZARDOUS WASTE
Figure 6. Frequency of detection for volatile organic compounds at an "average"
wood treatment facility and hazardous waste site.
-------
WOOD VERSUS HAZARDOUS WASTE SITES
»o%
SEM-VOLAH.ES - PERCENT DETECT
, ip , i »p «p 1> I
35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67
D WOOD TREATMENT
TARGET COMPOUND LIST
+ HAZARDOUS WASTE
Figure 7. Frequency of detection for semi-volatile organic compounds at an "average"
wood treatment facility and hazardous waste site.
-------
WOOD VERSUS HAZARDOUS WASTE SITES
100%
SEMI-VOLATI.ES - PERCENT DETECT
0% Ht
1 V I i r
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
~ WOOD TREATMENT
TARGET COMPOUND LIST
+ HAZARDOUS WASTE
Figure 8. Frequency of detection for semi-volatile organic compounds at an "average"
wood treatment facility and hazardous waste site.
-------
WOOD VERSUS HAZARDOUS WASTE SITES
PESTICDES - PERCENT DETECT
100%
90%
80%
70%
60%
50%
40%
30%
20% -
to%
0% $ tp tp tp
i}) i|»—^ ft fo—^—$—$—$—fp—tp-
100 101 »2103104105106107106109 110 Itl 112 113 114 115 116 117 118 119 120 121 122123124125126
~ WOO0 TREATMENT
TARGET COMPOUND LIST
+ HAZARDOUS WASTE
Figure 9. Frequency of detection for pesticides and PCBs at an "average" wood
treatment facility and hazardous waste site.
-------
1
2
3
i,
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
25
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
TABLE 1. TARGET COMPOUND LIST
CHEMICAL NAME
NUMBER
CHEMICAL NAME
CHV.OROMET HANE
64
2-NITROAN1LINE
BROMOMETHANE
65
DIMETHYL PHTHALATE
VINYL CHLORIDE
66
ACENAPHTHYLENE
CHLOROETHANE
67
2,6-OtNtTROTOLUENE
METHYLENE CHLORIDE
68
3-NITROANILJNE
ACETONE
69
ACENAPHTHENE
CARBON DISULFIDE
70
2,4 • DINITROPHENOL
1,1-OICHLOROETHENE
71
4-NITR0PHEN0L
1,1¦DICHLOROETHANE
72
DIBENZOFURAN
1,2-DICHLOROETHENE
71
2,4-DINITROTOLUENE
CHLOROFORM
74
DIETHYL PHTHALATE
1,2-DICHLOROETHANE
75
4¦CHLOROPHENYL PHENYL ETHER
2 -BUT AMONE
76
FLUORENE
1,1,1-TRICHLOROETHANE
77
4-NITROANILINE
CARBON TETRACHLORIDE
78
4,6-DINITRO-2-METHYLPHENOL
VINYL ACETATE
79
N-NITROSOOIPHENYLAMtNE
BROMOOICHLOROMETHANE
80
4-BROMOPHENYL PHENYL ETHER
1,2-DICHLOROPROPANE
81
HEXACHLOROBENZENE
CIS,1,3-D1CHL0R0PR0PENE
82
PENTACHLOROPHENOL
TRICHLOROETHENE
83
PHENANTHRENE
CHLORODIBROMOMETHANE
84
ANTHRACENE
1,1,2-TRJCHLOROETHANE
85
DI-N-BUTYL PHTHALATE
BENZENE
86
FLUORANTHENE
TRANS-1,3-DICHLOROPROPENE
87
PYRENE
BROMOFORM
88
BUTYL BENZYL PHTHALATE
4-METHYL•2¦PENTANONE
89
3t3'*D!CHLOROBENZ!D!HE
2-HEXANONE
90
BENZ(A)ANTHRACENE
TETRACHLOROETHENE
91
CHRYSEHE
TOLUENE
92
BIS(2-ETHYLHEXYL) PHTHALATE
1,1,2,2-TETRACHIOROETHANE
93
Dt-N-OCTYL PHTHALATE
CHLOROBENZENE
94
BENZO(B)FLUORANTHENE
ETHYLBENZENE
95
BENZO
-------
TABLE 2. WOOD TREATMENT
INDUSTRY AVERAGE (5 SITES) ¦
- BY PERCENT
DETECT
PERCENT
AVERAGE
# OF
COMPOUND NAME
PAH
DETECT CONCENTRATION
SITES
1
ACETONE
42%
20
4
2
METHYLENE CHLORIDE
42%
14
4
3
ACENAPHTHENE
C12
38%
805
5
4
NAPHTHALENE
CIO
35%
3312
5
5
FLUORENE
C13
34%
661
5
6
BIS(2-ETHYLHEXYL)PHTHALATE
32%
14
3
7
PHENANTHRENE
C14
29%
1825
5
8
DIBENZOFURAN
28%
332
4
9
2-METHYLNAPHTHALENE
Cll
27%
563
4
10
BENZENE
22%
33
4
11
FLUORANTHENE
C16
22%
1028
4
12
PYRENE
C16
22%
666
4
13
ANTHRACENE
C14
21%
425
4
14
TOLUENE
20%
48
4
15
ETHYLBENZENE
19%
39
4
16
XYLENE, TOTAL
18%
94
4
17
2,4-DIMETHYLPHENOL
13%
1219
3
18
BENZ(A)ANTHRACENE
C18
13%
280
4
19
CHRYSENE
C18
13%
249
4
20
ACENAPHTHYLENE
C12
13%
59
4
21
2-METHYLPHENOL
12%
1268
3
22
PHENOL
12%
1537
3
23
4-METHYLPHENOL
11%
3640
3
24
BENZO(B)FLUORANTHENE
C20
8%
121
3
25
BENZO(A)PYRENE
C20
8%
57
3
-------
TABLE 3. WOOD TREATMENT INDUSTRY AVERAGE (5 SITES) - BY AVERAGE CONCENTRATION
COMPOUND NAME
PAH
PERCENT
DETECT
AVERAGE
CONCENTRATION
§ OF
SITES
1
4-METHYLPHENOL
11%
3640
3
2
NAPHTHALENE
CIO
35%
3312
5
3
PHENANTHRENE
C14
29%
1825
5
4
PHENOL
12%
1537
3
5
2-METHYLPHENOL
12%
1268
3
6
2,4-DIMETHYLPHENOL
13%
1219
3
7
FLUORANTHENE
C16
22%
1028
4
8
ACENAPHTHENE
C12
38%
805
5
9
PYRENE
C16
22%
666
4
10
FLUORENE
C13
34%
661
5
11
2-METHY LNAPHTHALENE
Cll
27%
563
4
12
ANTHRACENE
C14
21%
425
4
13
DIBENZOFURAN
28%
332
4
14
BENZ(A)ANTHRACENE
C18
13%
280
4
15
CHRYSENE
C18
13%
249
4
16
BENZOIC ACID
2%
171
1
17
BENZO(B)FLUORANTHENE
C20
8%
121
3
18
XYLENE, TOTAL
18%
94
4
19
DI-N-OCTYL PHTHALATE
1%
60
1
20
ACENAPHTHYLENE
C12
13%
59
4
21
BENZO(A)PYRENE
C20
8%
57
3
22
TOLUENE
20%
48
4
23
ETHYLBENZENE
19%
39
4
24
BENZENE
22%
33
4
25
N-NITROSODIPHENYLAMINE
1%
22
1
-------
TABLE 4. CONTAMINANTS AT IDAHO SITE
CREOSOTE
AVERAGE
WASTE
GROUND WATER
WASTE/
COMPOUND NAME
PAH
(ug/L)
(ug/L)
GROUND WATER
NAPHTHALENE
CIO
6,400,000
3251
1,969
PHENANTHRENE
C14
5,000,000
543
9, 202
ACENAPHTHENE
C12
2,630,000
871
3 , 020
FLUORANTHENE
C16
2,140,000
187
11,475
PYRENE
C16
1,730,000
144
12,035
2-METHYLNAPHTHALENE
CXI
1,600,000
557
2,875
DIBENZOFURAN
1,180,000
302
3,909
BENZ(A)ANTHRACENE
C18
580,000
34
17,059
CHRYSENE
C18
300,000
21
14 , 286
BENZO(B+K)FLUORANTHENE
C20
230,000
14
16,429
BENZO(A)PYRENE
C20
170,000
9
18,889
PHENOL
85,000
45
1,889
INDENO(123CD)PYRENE
C22
32,000
3
10,667
2-METHYLPHENOL
25,000
99
253
BENZO(GHI)PERYLENE
C22
22,000
< 1
> 22,000
2,4-DIMETHYLPHENOL
21,000
117
180
ANTHRACENE
C14
< 1000
162
< 6
ACENAPHTHYLENE
C12
< 1000
11
< 91
FLUORENE
C13
< 1000
345
< 3
4-METHYLPHENOL
< 1000
132
< 8
-------
FATE AND TRANSPORT MODELING OF WOOD PRESERVING
CONTAMINANTS IN SURFACE WATER
Dr. Robert B. Ambrose, EPA-ORD, Athens, Georgia
-------
"Fate and Transport Modeling of Wood Preservative Contaminants in Surface
Water"
Rober B. Ambrose, Jr., P.E., Kendall p. Brown, Timothy A. Wool, Joyce A. Wool
1. Introduction
Chemicals
Pathways
Screening mass balance
Simulation modeling
2. Loading to the Stream
Screening calculation
Simulation
3. Stream Dilution
Screening calculation
Spread sheet calculation
Simulation
4. Bioconcentration
Screening calculation
Simulation
5. Discussion of Results
-------
"Modeling the Transport and Fate of Wood Preserving
Wastes in Surface Waters"
Robert B. Ambrose, Jr., PE1
Kendall P. Brown2
Timothy A. Wool3
Joyce A. Wool2
Hj.S. Environmental Research Laboratory, College Station Road,
Athens, GA 30613
2American Scientific International, Inc., College Station Road,
Athens, GA 30613
3Computer Sciences Corporation, College Station Road, Athens, GA 30613
-------
1. Introduction
Uncontrolled wastes from numerous wood preserving facilities pose an
unknown risk to aquatic communities and humans. Chemicals associated with
creosote, pentachlorophenol, and chromated copper arsenate are allowed to drip
from treated wood onto many sites. As chemical concentrations build up in the
soil, they threaten ground water through leaching and nearby streams through
runoff, erosion, and ground water transport. Driven by the hydrological
cycle, these processes are quite variable in time and space. Assessing
present and future exposure and risks at a given site requires a combination
of site monitoring and modeling. This paper explores the use of simple
calculations and more sophisticated simulation models in assessing potential
exposure and risk to the aquatic community and to humans through drinking
water and eating fish.
Simulations were conducted for pentachlorophenol at hypothetical half
acre sites situated 10m and 100m from Heath Creek near Rome, Georgia. The 37
km2 watershed receives an average of 1347mm of rain per year and yields a
stream discharge of 0.76 m3/sec (651mm/yr). Recorded discharge extremes range
from 0.034 m3/sec to greater than 20 m3/sec. Soil properties at the site were
assumed to reflect local Conasauga soils. Average grade was assumed to be 2%.
2. Screening Calculations
Risk assessments often begin with simple screening calculations to
assess whether exposure concentrations are expected to be much greater or much
less than aquatic criteria, drinking water standards, or fish tissue
standards. These calculations usually employ quite conservative assumptions
about the exposure scenario. The resulting margin of safety,
however, is usually uncertain, and can be resolved only by more detailed
monitoring and more sophisticated modeling.
The screening calculations for stream concentration assume that all
chemicals dripping from the wood reach the stream unattenuated:
Cw - Id VL / Q • 86400 • 365 (1)
where C„ - average stream concentration. mg/L
Ld - average drippage from lumber, g/m3
VL - volume of lumber treated, m3/yr
Q - average stream flow, m3/sec
CM may be directly compared to drinking water criteria, because cancer risk is
a long term average process. Aquatic toxicity, however, is a short term
event. Usually a' low flow with a specified return interval will be used in
Equation 1 to obtain the relevant stream concentration.
Screening calculations for whole fish concentration assume equilibrium
between fish tissues and the average water concentration:
-------
CF - Cw Kow fL
(2)
where _
CF - average whole fish concentration, ug/g
Kow - octanol-water partition coefficient, L^/L^,.
fL - fraction lipid content of fish
These calculations account for bioconcentration to lipid, but not to other
tissues. They ignore potential food chain bioaccumulation, which can be
important for chemicals with log K,^ greater than 5.
For the hypothetical Heath Creek site, the lumber drippage was taken to
be 4.36g PCP/m3. Combined with the treatment volume of 2.55 x 10* m3/year,
the average loading of PCP to the site is 304 g/day. Dividing by the average
flow of 0.73 m3/sec, the average stream concentration is calculated to be 4.6
ug/L. Given the log Kw of 5 and trout with a lipid content of 0.1, the
bioconcentration factor is 10*, and the average whole fish concentration is
calculated to be 46 ug/g. Little bioaccumulation is expected.
Several potential errors are present in these screening calculations.
First, not all the PCP drippage to the site should be expected to reach the
stream. Much of it may leach to ground water and never intercept the stream.
Second, PCP loadings to the stream via runoff and erosion will be highly
irregular, as will the daily stream flows. The average of daily
concentrations can be quite different from the volume-weighted average used in
the screening calculation. Third, high PCP concentrations during runoff
events may sorb to the benthic sediments. Desorption during subsequent days
may cause chronic low level contamination and raise average downstream fish
concentrations. Fourth, the extent of fish uptake and accumulation may be
affected by chemical speciation, unsteady loading, food chain bioaccumulation,
and metabolism. The significance of these calculated errors may be explored
using a series of simulation models that account for many of the appropriate
processes.
3. Models and Methods
The processes simulated In this study are illustrated in Figure 1. The
drippage load to the site was assumed to be a steady 304 g/day, as calculated
in the screening exercise. Daily runoff, erosion, and leaching fluxes were
simulated with the Pesticide Root Zone Model PRZM (Carsel et. al., 1985).
PR2M is based on the SCS curve number approach to hydrology, with transport,
partitioning, and degradation equations describing chemical fate.
Daily stream concentrations were calculated with simple dilution
equations implemented on spreadsheet:
^ii ~ (1*1 + LeiJ/Qi
C2i " Li/Qi
^31 " Cu + C21
(4)
(5)
-------
where
Lm - daily runoff loads, g/day
L^ - daily erosion loads, g/day
Ll - average leaching load, g/day
QA - daily stream flow, m3/day
Cu - daily stream concentrations from site receiving runoff and
erosion loads, mg/L
C2i - daily stream concentrations from leaching only, mg/L
C3i - daily stream concentratons from site receiving runoff, erosion,
and leaching loads, mg/L
Sorption and desorption were added as a first order attenuation process
following runoff events.
Daily whole fish concentrations were simulated with the FGETS model
(Barber et. al., 1988). FGETS is a toxicokinetic model that simulates the
bioaccumulation of nonpolar organic chemicals by fish from both water and
tainted food. Both of these routes of exchange are modeled as diffusion
processes that depend upon physico-chemical properties of the pollutant and
morphological/physiological characteristics of the fish. Two sets of
simulations were run. The first considered bioconcentration from water to
trout. The second included bioconcentration to sculpin and bioaccumulation in
trout eating sculpin.
4. Chemical Loading Simulations
PRZM was used to simulate daily runoff, erosion, and leaching fluxes
from sites that should be typical near Heath Creek. The principal hydrologic
parameters determining runoff and erosion are the curve number, precipitation,
and soil moisture. Daily meteorological data from NOAA climatological station
#7610 (Weather Bureau at the Rome, Georgia airport) were applied to this site
for the years 1950 to 1986. Soil moisture is calcualted daily by the model.
The principal site parameters determining erosion and runoff are soil type and
soil cover. Minimal vegetative cover was specified for these simulations.
Sparsely covered ground on poorly drained Conasauga soils will yield high
erosion and runoff fluxes. Average soil properties for three layers are given
in Table 1. The representative curve number chosen for this site is 91.
Table 1. Heath Creek Soil Data
Layer
Depth
cm
Sand
%
Clay
%
Organic
%
pH
Surface
10.2
25
15
0.50
4.8
Subsurface
48.3
15
47.5
0.17
4.8
Storage
76.2
15
50
0.10
5.05
-------
The principal chemical parameter determining rates of contaminant flux
is the partition coefficient. The octanol water partition coefficient Kow of
PCP varies with pH because the relative fraction of PCP as phenol and as
phenate varies with pH. The sediment water partition coefficient Kd varies
with Kow and soil organic content. K,j describes the partitioning of PCP
between aqueous and sediment phases only. Treated wood, however, receives PCP
dissolved in an oil carrier. This oil is mixed and carried with water
leaching or running off the site. A coefficient describing partitioning
between the oil-water emulsion and the sediment can be calculated from the Kd,
Kow, and the relative volumes of water V„ and oil V0:
v„ V
Ksow " Kd/( — + K^, ) (6)
V„ + Vc V„ + V0
The resulting partition coefficients are summarized in Table 2.
Table 2. Heath Creek PCP Partitioning Data
Layer
Depth
cm
(mg/LJ/Cmg/LJ
(ug/kgs) (mgAv)
(mg/kgs)/mg/Low)
Surface
10.2
59,000
80
0.71
Subsurface
48.3
59,000
27
0.21
Storage
76.2
42,000
12
0.15
The time series of erosion plus runoff loads are shown in Figure 2
(daily loads are shown averaged by month). Over the entire 18 year
simulation, the 304 g/day dripping to the site resulted in average runoff,
erosion, and leaching of 63 g/day, 1 g/day, and 231 g/day. The remainder,
about 3%, remained in the soil on site.
Runoff and erosion loads were assumed to reach the stream with no loss.
In reality, some deposition on the watershed below the site is expected.
Deposited chemical would be available to runoff and erosion as well as
leaching during subsequent rainfall events.
Leaching loads were assumed to reach ground water and be transported
toward the stream. Travel times though silt and sand aquifers can be
calculated as follows:
Ve - 365 K s/R
R - 1 + KpP/n
r - L/Vc
(7)
(8)
(9)
-------
where
Vc - velocity of the chemical, m/yr
K - hydraulic conductivity, m/day
s — slope
R — retardation factor
Kp - chemical partition coefficient
p - bulk density of the aquifer, g/cc
n - porosity, or water content
r - travel time, years
L - distance to stream, m
Assumed properties and calculations are summarized in Table 3. Travel times
for a sice 10m from the stream should range from a half year to 33 years.
Travel times calculated for the site 100m from the stream are 5 to 330 years.
The long travel times in combination with hydraulic dispersion should result
in averaged loads reaching the stream. Only a fraction of the contaminated
plume would be expected to intercept the stream. For these calculations, the
entire plume from the 10m site was assumed to reach the stream. For the site
100m from the stream, the plume was assumed to miss the stream entirely.
Table 3. Ground Water Transport
Parameter
Silt Aquifer
Sand Aquifer
K, m/day
1.5
7.5
n
0.3
0.45
P, g/cc
1.7
1.5
0.15
0.15
R
1.85
1.5
s
0.01 0.001
0.01 0.001
VCI m/yr
3.0 0.3
18 1.8
r, yr (10m)
3.3 33
0.56 5.6
r, yr (100m)
33 330
5.6 56
5. Stream Dilution Calculations
Daily stream concentrations subject to runoff, erosion, and leachate,
given by equations 3-5, were calculated by spread sheet. The time series of
fluxes from PRZM, in kg/ha-day, were first multiplied by 1000 ¦ 0.5/2.5 to
obtain loads in g/day from a half-acre site. Daily flows for Heath Creek, in
ft3/sec, were extracted from the USGS gaging record and multiplied by
-------
86400/35.3 to obtain flows in m3/day. Stream flows are shown in Figure 3.
The calculated stream concentrations subject to erosion and runoff loads only
are illustrated in Figure 4. Cumulative distribution functions are shown in
Figures 5 and 6. The mean concentration is 3.3 ug/L, corresponding to the
97th percentile. By contrast, mean erosion and runoff loads divided by the
mean flow give an average stream concentration of 1.0 ug/L.
The calculated stream concentrations subject to average leaching only
are illustrated in Figure 7. The mean concentration is 19 ug/L. Mean
leaching divided by mean flow gives 3.6 ug/L.
A site that contributes runoff, erosion, and steady leachate to Heath
Creek should produce a mean concentration of 22 ug/L. This compares to the
screening calculation of 4.6 ug/L.
The effect of benthic sorption and desorption subsequent to runoff
events was explored. During runoff events, a constant plane source equal to
the water concentration was assumed at the benthic surface. The concentration
distribution in the bed is given by
CBz / Cbo " 1 * erf (z/V4 Er At) (10)
and Er - Esw (1 + Kp p/n) (11)
where
CBz - concentration in pore water at depth z, mg/L
CB0 - aqueous concentration at benthic surface, mg/L
z - depth below benthic surface, m
At - elapsed time through event, days
Esw - sediment-water diffusion coefficient, m2/day
Er - retarded diffusion coefficient, m2/day
Kp - partition coefficient in bed, (nig/kg)/(mg/L)
p - bulk density of bed, g/cc
n - porosity of the bed, Lw/L
For an E,w of 10"3, of 105, p of 1, n of 0.4, and benthic organic fraction
of 10"2, the retarded benthic diffusion coefficient will be about 10"6 m2/day.
For events lasting 10"1 day, surface water concentrations will be 10 times the
daily average. Pore water concentrations are calculated to be a half and a
tenth of surface water concentrations at depths of 0.3mm and 0.7mm (designated
zQ 5 and z0-1, respectively). Total dissolved plus sorbed benthic
concentrations CBIl are given by
CBTz - CB2 (1 + K„ p/n) (12)
For this example, total concentrations are about 103 times per pore water
concentrations.
Following runoff events, desorption from the contaminated bed to the
surface water can be described by
CBz ~ CBl0 exp (-En t/z2)
(13)
-------
where
CbzO ~ pore water concentration at depth z at the end of the event, mg/L
t - elapsed time following event, days
Desorption half lives from various depths are given by
t1/2 - 0.693/CEr/z2) (14)
For depths where pore water concentrations begin at a half and a tenth of
surface concentrations, the quantity Er/z2 is 11.0 and 1.85 and half lives are
0.063 days and 0.37 days. Dividing the bed into two layers, we calculate that
the upper layer, containing about 75% of the sorbed mass, desorbs over 99% of
its mass by a half day following the event. The lower layer, containing about
25% of the sorbed mass, desorbs about 60% of its mass the first half day, 34%
during the next fully day and 5% over a following day.
The mass loading from the lower benthic layer following the event and
resulting surface water concentrations can be calculated by
Er A CB20
MBj - (1 + Kp p/n) exp (-Er t/z22) (15)
*2
and Ci+j - MBj/Qi+>) (16)
where
Z2 - the depth of layer 2, m
Cb2o ~ inital pore water concentration in layer 2, mg/L
A - benthic surface area contaminated by event, m
j - days following an event occuring at time i
Taking z, to be approximately z0 lf CB2o as 10 x 0.25 Cit a benthic area of A of
2.5 x 10* m2, flow of about 1 m3/sec, and other parameters as defined
previously, the water concentrations on days following a runoff event are
approximated by
Ci+J - Ct exp (-1.85 tj) (17)
Adding this function to the spread sheet, a new time series of water
concentrations was calculated. The average stream concentration for the
runoff and erosion case increased from 3.3 ug/L to 3.4 ug/L as a result.
6. Fish Bioaccumulation Simulations
FGETS was used to simulate whole fish concentration responding to the
concentration time series produced by runoff plus erosion and by leaching
alone. Two sets of simulations were run for each concentration time series.
The first set considered bioconcentration from water to trout only. The
second set considered bioaccumulation in trout eating sculpin equilibrated to
average PCP concentrations.
-------
One major complication required spread sheet adjustments prior to the
fish simulations. PCP ionizes from the neutral phenol to the anionic phenate
(designated PCP'). With a pKa of A.8, most molecules in surface water will be
as PCP . Only the neutral molecules exchange across fish tissue. Inside the
fish, aqueous PCP in the blood partitions to lipid and ionizes to PCP", which
also partitions to lipid. The sequence of reactions is shown in Figure 8.
The estimated equilibrium coefficients are based on surface water pH of 7.8
and blood pH of 6.8. The high affinity of PCP for lipid should result in
about 10 times more PCP than PCP" accumulating in whole fish. It was
concluded, then, that ionization inside fish could be ignored and that water
concentrations of PCP must be reduced by a factor of 1000 prior to the FGETS
simulations. This was accomplished on the spread sheet.
Because trout live about 10 years, only the first halves of the water
concentration time series were used. Trout whole body concentrations
responding to runoff and erosion loads and to leachate loads assuming no food
chain effects are illustrated in Figures 9 and 10. Mean trout concentrations
are 40 ppb and 277 ppb, reflecting a log bioconcentration factor of 1.2 (or
4.2 based upon the neutral PCP water concentration). These same mean fish
concentrations would have been obtained by running FGETS with the mean water
concentrations.
To investigate potential food chain effects, sculpin were simulated with
FGETS, and their mean concentrations fed to trout in a second series of trout
simulations. Mean sculpin concentrations were 24 ppb and 190 ppb for runoff
plus erosion and leaching, respectively. Both reflect a log bioconcentration
factor of 1.0 (or 4.0 based upon the neutral PCP water concentration). Mean
trout concentrations rose to 43 ppb and 300 ppb, reflecting a log
bioaccumulation factor of 1.25 (or 4.25 based upon the neutral PCP water
concentration). This one step food chain added only 8% to the trout
concentrations.
A final complication that could not be addressed in this study is the
metabolism of PCP within fish. FGETS at present does not contain an equation
for this process, and rates for trout are unknown. Because metabolism of PCP
in fish can occur, these simulations should be considered upper estimates.
7. Summary
The loading, dilution, and fish calculations are summarized in Table 4.
Site 1 is located 100m from Heath Creek, and delivers runoff and erosion
loads. Site 2 is located 10m from Heath Creek, and delivers runoff and
erosion loads as well as a steady average leaching load. Fish concentrations
have been extrapolated to the entire period of record using the
bioconcentration and bioaccumulation factors calculated by FGETS.
For site 1, the screening calculation overestimates the load by a factor
of 4.8 or 380%. The mean concentration is overestimated, however, by only
35%. The effect of ionization causes the screening calulation to overestimate
trout concentrations by a factor of 770. For a similar chemical that does not
ionize, the screening calculation would actually have underestimated fish
concentrations by 23%. Benthic desorption following events is insignificant.
-------
Table 4. Summary of Calculations
Calculation
L
g/day
Cw
PPb
CF
ppb
Screening
304
4.6
46 x 103
Site 1 Simulation1
63
3.3
52
Add benthic desorption
63
3.4
54
Add food chain
63
3.4
60
Site 2 Simulation2
294
22
350
Add food chain
294
22
390
xDaily runoff plus erosion
2Daily runoff, erosion, and mean leaching
Ignoring the one step food chain would cause about a 10% underestimate of
trout concentrations.
For site 2, the screening calculation overestimates the load by 3%, but
underestimates the mean water concentration by a factor of 4.8. The effect of
ionization causes the screening calculation to overestimate trout
concentrations by a factor of 120. For a similar chemical that does not
ionize, the screening calculation would have underestimated fish
concentrations by a factor of 8.5. Ignoring the food chain here would have
caused a 10% underestimate of trout concentrations.
The largest sources of uncertainty or errors found in this modeling
study are the effects of ionization on uptake, the amount of chemical
delivered to the stream from the site, and the effect of daily averaging
rather than volume weighted averaging. Food chain effects, not of major
importance here, are expected to be significant for longer food chains and
slightly more hydrophobic chemicals. Further uncertainty is associated with
possible complications arising from PCP behavior within fish, including
ionization and metabolism. These effects should be addressed with further
experimentation and model refinement.
-------
REFERENCES
Carsel, Robert F., Charles N. Smith, Lee A. Mulkey, J. David Dean, and Peter
Jowise. 1984. User Manual for the Pesticide Root Zone Model (PRZM). U.S.
Environmental Protection Agency, Athens, GA. EPA/600/3-84/109.
Barber, M.C., L.A. Suarez, and R.R. Lassiter. 1988. FGETS (Food and Gill
Exchange of Toxic Substances): A Simulation Model for Predicting
Bioaccumulation of Nonpolar Organic Pollutants by Fish. U.S. Environmental
Protection Agency, Athens, GA. EPA/600/53-87/038.
-------
Log Processing
Area
1
Q (dilution)
Figure 1
-------
Erosion & Run-off Load
0)
u>
I
D
>N
O
*
2
o
50
100
150
200
250
Time (months)
Figure 2
-------
Stream Flow for Heath Cree<
Time (month)
Figure 3
-------
Concentration in Stream
Erosion & Run-off
0.06
E
cf
.Q
O
O
0.04
0.03
0.02
0.01
0
¦ihmhiiiiiuiui:'.;
50
100
150
200
250
Time (Month)
Figure 4
-------
CDF for Stream Concentration
0.8
0 0:2 0=4 0.6 0.8 1 1.2 1.4 1.6
Goiicenbxition, mg/1
Figure 5
-------
CDF for Stream Concentration
0,95
0.85
-10 -8 -6 -4 -2 0 2
Loq Concentration, mq/1
3 Figure b
-------
Chemical Concentration in Stream
from Leachcite Loac
aos
om
0.04
0.02
o
3E+03 4£+03 5E+03 6E+03 7E-I-03
Time (days)
F^cvure 7
-------
WATER
— — — GILL
FISH
BLOOD
FISH
LIPID
10
PCP^=r RCP"
pH = 7.8
pKa = 4.8
\
PCP
/I
10
10'
PCP-
/I
/
10*
/
PCP;=^ PCP
Figure 8
-------
Trout Whole Body Concentration
1 T
0 500 1E+03 1.5E+03 2E+03 2.5E+03 3E+03 3:5E4-t)3 €4-03
Time (clays)
-------
Trout Concentration from Leachate
Time (days)
Figure 10
-------
CAPPING WOOD PRESERVING SITES
Dr. Walter E. Grube, EPA-RREL, Cincinnati, Ohio
-------
CAPPING WOOD PRESERVING SITES
INTRODUCTION
The closure of almost every contaminated site includes some type of
cover system. Although sometimes referred to simply as the "site cap", the
site cover is called upon to perform several functions. These may include
aesthetic beautification, retention of gases or vapors from escaping out from
the site, prohibition of entry of precipitation into underlying waste, pro-
vide a component of the relandscaping of an area, and others. Hydrologic
isolation of underlying waste is the most common criteria applied to cap
design, and the multiple components of a cover system are designed and built
to support this role.
A majority of wood preserving sites lie in humid climatic regions, where
reducing infiltration of rainfall is a major mechanism applied to reduce
leaching and loss of contaminants to the groundwater plume.
BACKGROUND DOCUMENTS ON COVER SYSTEMS
The EPA's Office of Research and Development has provided several com-
prehensive documents which describe the design and construction of caps or
covers for waste disposal sites. A pioneering effort first published in 1979
(USEPA, 1979) still remains a good foundation for cover design. The Agency's
Office of Solid Waste has issued a guide for evaluating cover systems (USEPA,
1982). More recently, ORD has issued a technical resource document directed
specifically toward covers on uncontrolled hazardous waste sites, of which
wood preserving sites comprise a subset (USEPA, 1985). An in-depth presenta-
tion of factors important in design, construction, and testing of compacted
soils built as a barrier to infiltration of rainfall into underlying wastes
is contained in a technical resource document primarily aimed at landfill
liner structures (USEPA, 1986). A Seminar series (USEPA, 1988) presented
throughout the United States during 1988 compiles and summarizes much of the
material presented in detail in the above references.
1
-------
COVER SYSTEMS IN HUMID REGIONS
The primary intent of nearly every cover system is to keep precipitation
out of the underlying waste material. Cover system designs to accomplish
this goal consist of several different layers of soil and other materials, in
a sort of sandwich arrangement. Figure 1 illustrates a typical series of
layers designed into a current cover system for either RCRA landfills or as
part of the remedy applied to old contaminated sites such as wood preserving
sites. The rationale and details of each major system component are discus-
sed in detail in the documents previously cited. Figure 2 shows a cover
system developed in studies in arid regions. The cobble layer which re-
stricts the burrowing of rodents is also likely to have an advantage in
restricting moisture movement downward from overlying soil. It provides a
capillary break. However this feature has not yet been studied in regions
where high rainfall provides a net moisture infiltration into soil.
One aspect of these classical multi-layer designs which has received too
little attention is the foundation for the cover--iri most cases this is waste
material deposited in a site. In the case of wood preserving sites, the
foundation is likely to consist simply of chemical-contaminated native soil
materials, often only little disturbed. The compacted soil barrier usually
is constructed at the base of the cover system, and is the first cover system
component directly overlying the waste in the landfill or the contaminated
soil in a remediated site, because of its unique function to provide as good
a barrier as possible to infiltration of precipitation into underlying site
material, the soil barrier must be built with a very high degree of struc-
ture.! integrity. This demands a sound foundation. With little experience in
specifying the degree of competence required in the foundation for a compacted
soil layer designed for very low permeebi1ity, we must, at present, leave
this design feature to tradition?l structural engineering. Therefore, we
must ensure that the foundation factor is adeouately presented in remedial
designs for cover systems.
The topsoil layer, to support vegetation, and the compacted soil barrier
layer are the parts of the cover system most often compromised in remedial
designs. This is simply because they consume the most soil materials, and
reductions here can easily lead to reduced overall costs.
t.
-------
Figure 1.
SCHEMATIC THREE-LAYER COVER SYSTEM
I
PRECIPITATION
evapotranspiration
i
VEGETATION j RUNOFF
• i i
" INFILTRATION
UJ
_J
u_
o
cr
CL
03
3
to
a:
UJ
Q.
a.
ID
0 VEGETATIVE LAYER
lateral drainage layer
LATERAL DRAINAGE
(FROM COVER)
L
SLOPE
BARRIER SOIL LAYER
PERCOLATION
(FROM BASE OF COVER)
cr
UJ
>
o
o
0-
<
o
@ WASTE LAYER
3
-------
VEGETATION ®
TOPSOIL
(60 CM)
GRAVEL FILTER
(30 CM)
BI OTIC
BARRIER
COBBLESTONE
(70 CM}
PROTECTIVE LAYER
FMB
COMPACTED SOIL
(90 CM)
GAS VENT
(30 CM)
WASTE
-------
In the topsoil, or the total soil zone in the surface of a cover system
which supports the root zone of the plants, we have a finite volume of mate-
rial which is the sole support of the planted vegetation. The physical
properties of this soil material need particular emphasis because the mois-
ture holding capacity, over all seasons of the year, is critical to plant
survival. Characterization of the moisture holding and release properties of
the vegetated soil materials appears to be a neglected parameter in cover
system design, materials selection, and construction. Vegetation established
on landfill or remedial site covers needs to be considered from the aspect of
plant ecology as well as immediate aesthetics. This simply means that a well
manicured lawn or pasture mix of grasses is unlikely to be as successful in
the long term, with low maintenance, as would be a less popular mixture such
as weeds and plants found in unmaintained low fertility soils.
Specifications for materials in cover systems, such as the seeds, plant-
ing schedule and related agronomic practices need to be written in contract
language. A common precedent useful to project managers unfamiliar with
revegetation can be found at state highway departments. P.evegetation of
roadsides and highway cut and fill material would include many of the prac-
tices that need to be applied to grow plants on a soil placed as the top of a
cover system. Experience also exists in recions where mined land has been
regraded and plant established by contract construction firms. State Depart-
ments of Natural Resources, or Bureaus of Mines are the typical contacts for
site remediation in this industry. When consulting with agencies that have
related experience, academic agronomists, and mission-oriented professionals
such as SCS soil surveyors or practicing soils engineers, one must continue
to recognize that their expertise and orientation is likely to be much nar-
rower than application to a waste-contaminated soil area. Therefore the
remedial design reviewer mus-t personally integrate the oriented bits of
technical advice from these several related technical experiences into a plan
that appears best for a particular site. The field of environmental cleanup
is still young in the area of multidisciplinary -technical integrators with
substantial experience.
Most remedial design guidance provides idealized diagrams (Figure 3) and
line drawnings of cover systems which design engineers are requested to use
-------
Figure 3.
6
-------
as the basis for cover designs on sites which are non-ideal. Few sites in
the field are of uniform dimension, with no interfering natural features such
as slopes, ravines, powerline right-of-ways, property boundaries, wetlands,
etc. The construction blueprints we have seen leave a great deal to the
imagination of the field superintendent with regard to the actual cover
system material placement. . A clear picture of how the various cover mate-
rials will be handled is necessary so that compromises in material and con-
struction do not occur which compromise the intended hydrologic performance
of the total cap. Included in this part of the design should be also the
construction sequence. With a great deal of earth material being hauled in
and moved around, there must be a preplanned clear picture of which truckload
of what comes first, next, and where.
Complexities in material needs and material handling drive cover system
designs to include less soil material and either amendments such as bentonite
or synthetic plastic materials as the primary precipitation barriers. Each
of these options generates a great deal of detailed discussion of pros and
cons. Our research laboratory has investigated and published numerous reports
in recent years regarding the barrier properties of a wide range of these
types of materials.
Questions have arisen regarding the use of asphalt, cement, fly ash
additives, and other particular materials to cap a site, either instead of,
or on an arc?, separate from that covered by a multi-layer cover system.
Where a structure or parking lot or ether land use requires p. cap based on
structural use, concrete or asphalt may be the best alternative. However we
have not seen any data which show that extensive areas paved by road building
practices approach the low permeability to precipitation that a well-con-
structed system provides. Construction practices that are classical for
traffic and structural load-hearing have not been shown to provide low per-
meability to hydraulic flow. We are still looking for data which show that
traditional measures of soil materials' engineering characteristics directly
predict hydraulic containment properties. Even the measurement of hydraulic
conductivity of compacted fine-grained soils has been subjected to extensive
research in the laboratory and field. The results show simply that this
parameter needs to be measured in each site- and material-specific case in
7
-------
order to be assured that the desired low permeability can be obtained in a
liner or cover structure. Concrete and asphalt laid to road building speci-
fications are both too porous and cracked to provide a barrier to infiltra-
tion.
Questions regarding the effects of freeze/thaw on compacted soil in a
cover system are just now beginning to be investigated. The preliminary .
studies conducted by the Corps of Engineers and DOE are not conclusive. The
current best advice seems to be to insulate or cover the compacted low-per-
meability layer as deep as possible to be out of reach of frost. Since no
definitive data yet exist on whether freezing is detrimental, placement below
the "average depth of frost penetration" is the current accepted design.
The quality of the construction of RCRA waste management facilities has
been studied by our Laboratory. Essential aspects of Quality Assurance/
Quality Control have not been as clearly documented for remedial design and
construction activities, but we believe them to be at least as important and
significant to a successful remedy as we find in RCRA facilities. We have
published a document (USEPA, 1986a), which emphasizes RCRA facilities, but
would be a good guide to operations under SARA which should be examined with
respect to construction quality.
CONCLUSION
The references cited earlier provide a great deal of details on cover
system design. The reader must be alert to areas in these writings where the
civil engineering has not yet made the transition from load-bearing structures
to low-leakage containment structures. Agency staff responsible for design
of remedial activities applied to wood preserving sites are burdened with
being the integrator of knowledge and technical information from a variety of
technical disciplines and sources. This paper is intended to provide direc-
tion toward the various resources available to ease these tasks.
8
-------
REFERENCES
USEPA. 1979. Design and Construction of Covers for Solid Waste Landfills.
EPA-600/2-79-165. Available from NTIS as No. PR 80 100381.
USEPA. 1982. Evaluating Cover Systems for Solid and Hazardous Waste.
SW-867. Available from Office of Solid Waste and Emergency Response, USEPA,
Washington, D.C. 20460.
USEPA. 1985. Covers for Uncontrolled Hazardous Waste Sites. EPA/540/2-
85/002. Available from CERI, USEPA, Cincinnati, OH 45268.
USEPA. 1986. Design, Construction, and Evaluation of Clay Liners for Waste
Management Facilities. EPA 530/SW-86-007. Available from NTIS as PB 86
184496.
USEPA. 1986a. Technical Guidance Document: Construction Quality Assurance
for Hazardous Waste Land Disposal Facilities. EPA/530-SW-86-031. OSWER
Policy Directive No. 9472.003.
USEPA. 1988. Seminars—Requirements for Hazardous Waste Landfill Design,
Construction, and Closure. CERI-88-33. Available from CERI, USEPA,
Cincinnati, OH 45268.
9
-------
STABILIZATION/SOLIDIFICATION OF METALS IN SOILS AND SLUDGES
Edwin F. Barth, EPA-RREL, Cincinnati, Ohio
-------
THE USE OF SOLIDIFICATION/STABILIZATION
FOR WOOD TREATING SITES
by
Edwin F. Barth, P.E.
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
-------
Solidification/stabilization technology may be a viable alternative for
many corrective actions at uncontrolled hazardous waste sites. Solidifica-
tion implies the hardening of a waste matrix, which may also decrease
contaminant leaching while stabilization implies a chemical reaction to
decrease chemical leaching.
Solidification/stabilization using pozzolanic material is generally
considered applicable for soils contaminated with heavy metals. However, the
physical and chemical characteristics of each soil matrix makes upfront
treatment predictions difficult. A solidification/stabilization study for
the Office of Solid Waste's BDAT Program (see Table 1) was effective for
reducing TCLP leachates for As, Pb, Cu, Cd and Zn^ in the BDAT contaminated
soil matrix. However, CCA contaminated soils contain two metals that are
thought to be difficult to stabilize arsenic and chromium as Cr+6.
There are many unknowns when considering solidification/stabilization
for organic wood treating waste. High concentrations of oil and grease can
2
impede the setting of a curing sample . In general, pozzolanic material may
only solidify, but not stabilize an organic waste. Pozzolanic material was
not successful in decreasing TCLP leachate concentrations of semivolatile
compounds^ in the BDAT study.
The state-of-the-art of solidification/stabilization for organic waste
is the use of alternative binding agents such as surfactants, polymers, or
modified clays (organophi1ic clays). Recent studies have shown promise for
modified clays3'4. Table 2 shows that the TCLP leachate of some organic
compounds may be substantially reduced after stabilization with a modified
clay. Asphaltic material has been evaluated for stabilizing dioxin contam-
inated soil , which could be present on a creosote site.
The major issues involving the stabilization of hazardous waste is the
permanence or long term stability of the treated waste. This depends on many
factors, such as the binder used, potential redox reactions, waste setting
and management controls. As yet, no leachate test or set of tests have been
agreed to mimic long term disposal conditions.
-------
REFERENCES
1. Weitzman, L., Hammel, M., and Barth, E. "Assessment of Solidifica-
tion/Stabilization as a BOAT for Contaminated Soils", HWERL Symposium
Proceedings, Cincinnati, Ohio. 1987.
2. Jones, L. "Interference Mechanisms in Waste Stabilization/Solidifica-
tion Processes", Literature Review. EPA/COE 1AG DW219306080-01-0, 1988
3. Soundarajan, R., and Gibbons, J. "The Nature of Bonding in Stabiliza-
tion Processes", Analytical Chemistry. 1988.
4. Soundarajan, R., and Barth, E. "The Evaluation of an Organophilic Clay
for Chemically Stabilizing a Waste Containing Organic Compounds".
(In press)
5. Vick, W., et.al., "Physical Stabilization Techniques of Environmental
Pollution from Dioxin Contaminated Soils". Journal of Hazardous
Materials 18. (1988).
-------
TABLE 1. SUMMARY OF TCLP RESULTS FOR METALS
(SAHM)
Saaple
Binder
Arsenic
Cadmium
Chromiun
Copper
Lead
Nickel
Zinc
No.
(Day)
a
b
a
b
a
b
a
b
a
b
a
b
a
b
I
RAW
ND
0.53
ND
0.61
0.49
0.27
9.2
1
FC(14)
ND
-
ND
100
0.06
+
0.07
81
0.15
75
0.04
70
0.23
96
14
KD(14)
ND
-
ND
100
0.06
+
0.04
81
ND
100
ND
100
0.27
94
27
LF(14)
ND
-
ND
100
0.02
+
0.03
98
ND
100
ND
100
0.14
94
I
PC(28)
ND
-
ND
100
0.06
+
0.06
83
0.15
75
0.04
70
0.49
91
15
KD(28)
ND
-
ND
100
0.09
+
0.03
80
ND
100
ND
100
0.62
73
27
LF(28)
ND
-
ND
100
0.02
0.03
98
ND
100
ND
100
ND
100
II
RAH
ND
0.73
ND
0.89
0.7
0.4
14.6
4
PC(14)
ND
-
ND
100
0.03
+
0.04
92
0.15
82
0.04
83
0.09
99
16
KD(14)
ND
-
ND
100
0.08
+
0.07
79
0.44
+
ND
100
0.25
97
30
LF(14)
ND
-
ND
100
ND
-
ND
100
ND
100
ND
100
0.22
99
4
PC(28)
ND
-
ND
100
0.03
+
0.06
89
0.15
83
0.04
83
0.54
94
16
KD(28)
ND
-
ND
100
0.05
+
0.09
89
0.37
+
ND
100
0.78
89
29
LF(28)
ND
ND
100
ND
-
0.03
90
ND
100
ND
100
0.02
100
III
RAN
6.39
33.1
ND
80.7
19.9
17.5
359
7
PC(14)
ND
100
ND
0.07
+
0.15
100
0.63
95
ND
100
0.58
100
21
KD(14)
ND
100
ND
100
0.22
+
1.02
96
13.3
+
ND
100
4.38
95
33
LF(14)
0.81
52
0.02
100
0.03
+
2.96
87
51
+
ND
100
3.81
96
7
PC (28)
ND
100
ND
100
0.07
0.09
100
ND
100
ND
100
0.69
100
21
KD(28)
0.21
98
ND
100
0.12
+
0.85
96
18.3
+
ND
100
4.07
95
33
LF(28)
0.79
51
0.02
100
0.07
+
2.59
87
51
+
0.03
99
3.97
96
IV
RAW
9.58
35.3
0.06
10
70.4
26.8
396
10
PC(14)
ND
100
ND
100
.0.06
+
0.14
100
0.39
99
ND
100
0.39
100
23
D>(14)
0.16
95
ND
100
0.11
+
1.88
97
12.4
43
ND
100
4.57
97
LF(14)
1.61
50
ND
100
0.07
+
1.92
96
91.8
+
ND
100
3.22
96
10
PC(28)
ND
100
ND
100
0.06
+
0.17
100
0.37
99
ND
100
0.74
100
23
KD(28)
0.27
92
ND
100
0.12
1.67
97
21.4
9
ND
100
3.72
97
LFf28)
0.98
59
0.02
100
0.07
•f
2.18
95
65
+
ND
100
3.64
96
Detection Liait 0.15
0.01
0.01
0.02
0.15
0.04
0.01
Notes: (a) TCLP results in ppn ND - below detection lialt
(b) percent reduction, corrected for dilution + - increase over raw SAHM
Source: reference 1
-------
TABLE 2.
S/S DATA - WHITEHOUSE, FLORIDA
RAW(ppb) TWA (pp.b) TCLP(ppb)
Bis-ether 8,528 ND ND
Naphthalene 18,060 1,445 ND
Phenanthrene 20,184 ND ND
Benzo-anthracene 30,460 ND ND
Source: reference 4
-------
STABILIZATION/SOLIDIFICATION
OF METALS IN SOILS AND SLUDGES
by
Edwin F. Barth
MUNICIPAL SOLID WASTE AND RESIDUALS MANAGEMENT BRANCH
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO
-------
S/S PURPOSE
TO DECREASE LEACHING:
SOLIDIFICATION (NONSOLID •* SOLID)
VS.
STABILIZATION (CHEMICAL REACTION)
-------
S/S APPLICABILITY
• Lead (Pb)
• Nickel (Ni)
• Zinc (Zn)
• Copper (Cu)
• Cadmium (Cd)
• Chromium(lll) (Cr+3)
• Low-level organics
• Chromium(VI) (Cr+6)
• Arsenic(lll) (As+3)
• Arsenic(V) (As+5)
• Mercury (Hg)
• High-level organics
-------
CHEMICAL REACTION MECHANISMS
• PRECIPITATION AS:
HYDROXIDES (OH)
SILICATES (Si)
SULFIDES (S)
• GOMPLEXATION
• ORGANIC BINDING
-------
S/S OF ORGANIC MATERIAL
IN GENERAL, POZZOLANIC MATERIAL WILL NOT
BIND ORGANICS; AN ORGANOPHILIC BINDER MUST
BE USED FOR STABILIZATION.
NOTE: PCB DECHLORINATION?
-------
S/S INTERFERING COMPOUNDS
• SULFATES (S04)
• NITRATES (N03)
• PHENOLS
• OILS GREASE
-------
SOIL VARIABLES IMPACTING S/S
• GRAIN SIZE DISTRIBUTION
• COHESIVENESS
• CATION EXCHANGE CAPACITY (CEC)
• "ACID" CONTENT (HUMIC, FULVIC)
• PARTITIONING (TOTAL ORGANIC CARBON)
-------
S/S OF CREOSOTE WASTE
• Cu
• Cr+6-> Cr+3
• As + complex
• PCP (oily)
-------
SIS LEACHING/EXTRACTION VARIABLES
• MONOLITHIC VS. GRINDING
• DYNAMIC VS. STATIC
• TYPE AND PREPARATION OF EXTRACT
-------
S/S LEACHING/EXTRACTION TESTS
• EXTRACTION PROCEDURE (EP) TOXICITY
• TOXICITY CHARACTERISTIC LEACHING PROCEDURE (TCLP)
• MONOFILLED WASTE EXTRACTION PROCEDURE (MWEP)
• TOTAL EXTRACTION
• ANS116.1
• MCC-1P
• EQUILIBRIUM LEACH TEST
• SEQUENTIAL CHEMICAL EXTRACTION
-------
S/S PHYSICAL TESTS
• UNCONFINED COMPRESSIVE STRENGTH (UCS)
• PERMEABILITY
• WET/DRY
• FREEZE/THAW
• COMPACTION
• DENSITY
-------
TCLP LEACHING PROCEDURE
METALS (pH = 2)
BASE NEUTRALS
ACID
EXTRACTABLES
(pH = 3)
oH = 12
-------
PHASE I BDAT CHEMICALS
METALS VOLATILES
PbS04 ACETONE
ZnO CHLOROBENZENE
CdS04 1,2-DICHLOROETHANE
As203 ETHYLBENZENE
CuS04 STYRENE
Cr203 TETRACHLOROETHYLENE
Ni (NO ) XYLENE
SEMIVOLATILES
ANTHRACENE
BIS-PHTHALATE
PENTACHLOROPHENOL (PCP)
-------
S/S DATA - WHITEHOUSE, FLORIDA
RAW (ppb) TWA(ppb) TCLP(pph)
Bis-ether 8,528 ND ND
Naphthalene 18,060 1,445 ND
Phenanthrene 20,184 ND ND
Benzo-arithracene 30,460 ND ND
-------
ORGANOPHILIC CLAY
Al
R N R
/sT\
-------
SUPERFUND CREOSOTE SITES EVALUATING S/S
• SHERIDEN DISPOSAL
• AMERICAN CREOSOTE
• J. H. BAXTER
• PALMETTO WOODS
-------
CONTRACT SPECIFICATIONS
PERFORMANCE SPECS
VS.
TIGHTLY WRITTEN SPECS
-------
BUYER BEWARE
• RELEASE OF VOLATILES
• DILUTION
• PCB ANALYTICAL TECHNIQUES
• PROPRIETARY AGENTS
• COST
-------
SLURRY WALLS, RECOVERY WALLS, INTERCEPTOR TRENCHES,
AND GROUT CURTAINS
Dr. Walter E. Grube, EPA-RREL, Cincinnati, Ohio
-------
SLURRY WALLS FOR GROUNDWATER ISOLATION AT WOOD-PRESERVING SITES
Walter E. Grube, Or.
Soil Scientist
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
INTRODUCTION
Vertical barriers to groundwater and pollutant migration have become
common structures for isolation of groundwater contaminants. Within EPA's
Superfund program, containment of liquids within a site has been accepted as
a practical means to meet two goals: 1) to reduce the migration of ground-
water pollutants from a site during the time that a treatment, destruction,
or removal technology is being applied; and 2) to reduce the volume of
groundwater coming into and through a site, so that less total volume needs
to be treated for pollutant destruction or removal.
The "slurry trench cut-off wall" has been adopted from the standard civ-
il engineering practice as the most common groundwater barrier. This struc-
ture consists of a trench maintained open by addition of a clay slurry during
excavation; after reaching the desired depth and linear extent, the trench is
backfilled with a material of lower groundwater permeability than the origi-
nal soil or geologic formation that was excavated. The use of suspended clay
slurries to maintain open excavation in coarse-grained and saturated soils
has been extensively discussed in construction engineering literature (Gill,
1978; Millet et al., 1981; Ryan, 1976). The trench backfill commonly con-
sists of a mixture of soil excavated from the trench with bentonite clay and
other fine-grained materials designed to provide a relatively even distribu-
tion of many different soil particles in the final backfill mix. In specific
circumstances, Portland cement has been a major backfill component where
structural rigidity was required of the trench area. Other vertical barrier
excavation or construction techniques and barrier material formulation have
1
-------
been applied by various commercial companies and for particular site condi-
tions (Case International, 1982).
A substantial mobilization of construction equipment is needed to in-
stall a slurry trench cut-off wall. The corporate brochure of International
Technology (IT) Corporation contains a color photograph which shows the
entire installation construction activity at a site where they installed 1600
lineal feet of barrier (International Technology Corporation, 1986). Fig-
ure 1 depicts the various activities at this site where 3.6 acres was encir-
cled to a depth of 100 ft.
Slurry Trench
This method of excavation has been used by civil engineers for many dec-
ades. It is economical where the soil material is so friable that the walls
of an open trench will collapse during excavation unless they are shored up
by some means. Sheets of plywood or steel panels are very expensive, and can
be dispensed with where the excavation is a narrow trench that can be filled
with a suspended clay during excavation. Common trench excavators can con-
tinue to dig through a water-filled trench. Traditionally, bentonite clay
has been the routine material added to the trench to maintain it open until a
backfill material has been placed. Numerous reports of experience with this
material have been published (D'Appolonia, 1980). Recently, other materials
such as attapulgite clay plus surfactants, and protein-rich gum material from
organic and biochemistry processes have been tested or used at particular
slurry trench projects.
Cut-Off Wall
The backfill or other material placed within a trench excavated in a
water slurry creates the groundwater barrier desired at a site under remedial
action. The most common trench backfills consist of a mixture of soil and
bentonite clay (SB) or port!and cement, bentonite clay, and soil material
(CB). Soil/bentonite backfill normally consists of the soil material ob-
tained during trench excavation along with commercially obtained bentonite
clay added to increase the content of fine-grained particles. Locally ob-
tained clay from a borrow pit is also often added to increase the fines
content of the backfill. Ideal SB backfills should contain an assortment of
0
L,
-------
backfilling begun with
tremie placement to establish
contact with trench basement
and providyproper slope
site access
Bentonite hydration
ponds
G D
site
I perimeter
fence
office trailed
backhoe at leading
edge of trench
clamshell buckets on
cable from crane
trench spoil
site boundary
Figure 1. Equipment and activities at the site of
construction of a slurry trench cut-off wall.
3
-------
soil materials that includes an even distribution of the range of soil parti-
cle sizes. This assortment has the greatest potential for all pore space in
the backfill to be occupied by solids, thus reducing permeability to the
groundwater. Backfill containing sufficient cement or other pozzolan to
harden in place is often used either where structural strength is desired in
the completed barrier, or there may be inadequate amounts of soil materials
available at economic rates. Recent engineering designs have included inter-
locked sheets of synthetic flexible membrane liner materials (FML) inserted
into the slurry trench to provide a water migration barrier of lower permea-
bility than obtainable with soil or cement mixtures. Use of such synthetic
barriers in slurry trenches is very young and only one or two examples have
so far been reported in technical journals.
The utility of bentonite clay in slurry trench construction must be men-
tioned because of the great commercial market for this commodity. The physi-
cal and chemical properties of bentonite were characterized by geologists and
clay mineralogists many decades ago. Their data were immediately applied by
engineers, primarily oil well drillers, where "drilling mud" was enriched
with bentonite because of its capability to both lubricate the drill stems
and carry suspended drill cuttings out of deep wells to the surface. This
use remains a very large market. Bentonite clay is the commercial or collo-
quial name for naturally-occurring clay deposits which contain the clay-sized
mineral montmorillonite as the dominant constituent. Volumes of technical
literature exist which present almost any aspect of bentonite clay and mont-
morillonite mineralogy (e.g., Jepson, 1984). The action of bentonite clay in
a slurry trench to maintain the trench open during excavation has been dis-
cussed in detail in engineering publications (Millet et al, 1981). In recent
years, other materials have been suggested and tried for use as a slurry
trench water suspension agent. Bentonite remains favored by many designers
because when some of the trench slurry is used in mixing the backfill, some
amount of bentonite is included, which adds to the fines content of the
backfill, providing a lower permeability of the final backfill mixture.
SLURRRY TRENCH CUT-OFF WALLS FOR POLLUTION MIGRATION CONTROL
Early in the consideration of engineering technologies and structures
that could be applied to clean up uncontrolled hazardous waste sites, the
4
-------
"slurry trench cut-off wall" was included in remedial designs (U.S. EPA,
1984). This structure was included for one or both of two groundwater con-
trol reasons: 1) to restrain contaminated groundwater from leaving a site so
that the groundwater cleanup technologies could be activated, and 2) to
reduce the quantities of offsite groundwater entering the site, thus reducing
the dilution of contaminants and the total amount of contaminated groundwater
that would need to be treated to remove pollutants.
Slurry walls as barriers early resulted in studies of the degree to
which groundwater flow was reduced, which lead to laboratory measurement of
the permeability of backfill materials. Traditional methods of study of soil
permeability were applied, and many data were published, with some studies
continuing today. Laboratory permeability testing is a routine operation in
characterizing a proposed backfill mixture. A major consideration is whether
the site groundwater contaminants are chemically aggressive and will react
with backfill components (reaction with bentonite clay is a major concern),
leading to reduced permeability after backfill installation. Several pub-
lished reports present the current state-of-the-art in laboratory permeabili-
ty testing (Carpenter, 1986; Daniel, 1984; Evans, 1986).
The actual hydraulic attenuation performance of an installed cut-off
wall has been documented in very few cases.
Compatibility Testing
The laboratory permeability test of cut-off wall backfill materials has
become the primary measure of compatibility of the barrier with the ground-
water in which it will be in contact. Although several studies have reported
the influence of permeant liquid composition on the hydraulic conductivity of
cut-off wall backfill mixtures, a great deal of the concern for the potential
for adverse chemical interactions derives from studies of solvent effects on
compacted clay soil landfill liners. Grube, 1987, summarized these numerous
studies. If the groundwater contains solutes that will degrade the barrier,
this factor should be determined early in the design stage of the cut-off
wall. Acceptance of a cut-off wall within remedial designs usually requires
submission of data showing that the selected backfill does not change permea-
bility after the permeant fluid has been passed through. The permeant liquid
5
-------
is usually chosen to be either actual contaminated groundwater from a site or
a synthetic mixture created to simulate chemically aggressive groundwater.
There does not appear to be a well-recognized universal formula for mixing
laboratory reagents to simulate an aggressive groundwater; each formulation
is generally site-specific. Evans and Fan, 1986, present a description of
the laboratory method that is widely applied to determine groundwater/barrier
compatibility.
A particular situation in which compatibility testing of both trench
slurry and backfill is essential lies in regions where the marine environment
is a strong influence on groundwater composition. Since sodium-bentonite
will lose this cation and corresponding swelling capacity in the presence of
cations such as calcium and magnesium from sea water, the extent of this ex-
change must be determined early in the design of a cut-off wall in this envi-
ronment. Commercial bentonite clay suppliers claim they both have bentonite
clay formulations which resist ion exchange in marine environments and also
provide laboratory testing services to demonstrate the performance of their
products. The cut-off wall designer should be sure that compatibility tests
are conducted in an unbiased manner and that procedures well recognized for
relevance are used.
A special area requiring attention in the case of wood-preserving sites
is the potential presence of immiscible liquids sunken or floating in the
site groundwater. These liquid pollutants can be either penta- or other
chlorophenols, probably with diesel fuel floating on the phreatic surface or
creosote-based residues pooled on the surface of a less-pervious geologic
strata at some depth in the site's groundwater. It is clear that where a
cut-off wall intersects such immiscible pools of contaminants, the potential
for chemical degradation of the barrier is high, and will not be reflected by
tests of trench slurry or backfill mixtures where normal groundwater from the
site has been used. In sites where there is a possibility of the presence of
immiscible pools, there must be sufficient credible data from groundwater re-
gime characterization to identify them. In the past, there has not appeared
to have been much concern for determining localized contaminant regions
during site characterization, but this must be considered in barrier design.
6
-------
In-Situ Performance Monitoring
Data which show the degree to which an installed groundwater cut-off
barrier has been effective are sparse in open published technical journals.
Barrier effectiveness has been evaluated in terms of how much lower the
concentration of certain solutes is in monitoring wells outside the cut-off
wall versus inside the structure. Another measure has been the decrease in
groundwater elevation inside the structure relative to the ambient outside.
Probably the most well-documented study of the hydrologic effect of
cut-off wall installation at a Superfund site is that which the EPA's Office
of Research and Development conducted at the Sylvester Site in Nashua, New
Hampshire (U.S. EPA, 1987).
Both the U.S. Army Corps of Engineers in individual districts, and pri-
vate corporations who plan installation of groundwater containment or isola-
tion barriers have required pilot-scale construction of barriers in order to
qualify construction contractors. These pilots consist of an area, perhaps
50 feet square, surrounded by a cut-off wall built by a contractor in a man-
ner similar or equal to what we would build if granted a contract for several
thousand lineal feet of barrier. The "test box" has monitoring wells in-
stalled both inside and outside, and pump-down tests are conducted on well(s)
inside the "test box". Data obtained from well water levels are used to cal-
culate the permeability of the barrier system, and results are compared with
design expectations or regulatory requirements. Data from Corps of Engineers
projects repose in the individual district and site files, and data from
private corporations are largely unavailable except perhaps in local or state
permitting agency files.
It is known that data have been collected at full-scale groundwater
cut-off wall installations, which would document the barrier's hydrologic
performance. Sites such as Rocky Mountain Arsenal, Li pari Landfill Superfund
Site, and several installations by private corporations to meet individual
states' remedial requirements have generated data which have not been fully
reported in open technical journals. The extent to which particular regional
or state regulatory agencies have compiled or summarized these data is un-
known.
7
-------
CONCLUSIONS
Groundwater barriers constructed using slurry trench techniques have
been routinely constructed by civil engineers for many years. Since the late
1970's, an undocumented number (perhaps in the range of 20 to 30) have been
installed specifically to control the migration of groundwater contaminated
with hazardous waste solutes.
Testing the barrier filling mixture to verify that.it will not signifi-
cantly change permeability in the presence of the site contaminated ground-
water relies primarily on laboratory permeability test procedures. Methods
for these procedures have not been formally standardized. Reports of studies
in geotechnical journals form the basis for conducting compatibility tests.
Data which illustrate the effectiveness of a cut-off wall after instal-
lation are largely unsumtnarized and repose within individual site files of
cognizant regulatory offices. Methods to reliably measure and document the
in situ hydrologic performance of groundwater barriers have not been clearly
developed and published.
REFERENCES
Carpenter, G. W., and R. W. Stephenson. 1986. Permeability Testing in the
Triaxial Cell. Geotech. Testing J., GTJODJ, ASTM, Vol. 9, No. 1, March,
pp. 3-9.
Case International. 1982. Slurry Wall Technical Information Review. Case
International Co., Roselle, Illinois. 37 pp.
Daniel, D. E., S. J. Trautwein, S. S. Boynton, and D. E. Foreman. 1984.
Permeability Testing with Flexible-Wall Permeameters. Geotech. Testing J.,
GTJODJ, ASTM, Vol. 7, No. 3, September, pp. 113-122.
D'Appolonia, D. J. 1980. Soil-Bentonite Slurry Trench Cutoffs. J. Geotech.
Eng. Div. ASCE, Vol. 106, No. GT4, April, pp. 399-417.
Evans, J. C., and H. Y. Fang. 1986. Triaxial Equipment for Permeability
Testing with Hazardous and Toxic Permeants. Geotech. Testing J., GTJODJ,
ASTM, Vol. 9, No. 3, September, pp. 126-132.
Gill, S. A. 1978. Applications of Slurry Walls in Civil Engineering
Projects. Preprint 3355, ASCE Convention, Chicago, Illinois. 20 pp.
Grube, W. E., Jr., M. H. Roulier, and J. G. Herrmann. 1987. Implications of
Current Soil Liner Permeability Research Results. In: Proceedings of 13th
Annual Research Symposium, Land Disposal, Remedial Action, Incineration, and
Treatment of Hazardous Waste, EPA/600/9-87-015, pp. 9-25.
8
-------
International Technology Corporation. 1986. Profile of Environmental Ser-
vices. Descriptive corporate brochure. 16 pp.
Jepson, C. P. 1984. Sodium Bentonite: Still a Viable Solution of Hazardous
Waste Containment. Pollution Eng. April. 3 pp.
Millet, R. A., et al. 1981. Current USA Practice: Slurry Wall Specifica-
tions. J. Geotech. Eng. Div., Proc. ASCE, Vol. 107, No. GT8. August, pp.
1041-1056.
Ryan, C. R. 1976. Slurry Cut-Off Walls Design and Construction. Technical
Course on Slurry Wall Construction, Design, Techniques, and Procedures.
Chicago, Illinois. 20 pp. Available from the author, c/o Geo-Con, Inc.,
Pittsburgh, Pennsylvania.
U.S. Environmental Protection Agency. 1984. Slurry Trench Construction for
Pollution Migration Control, EPA-540/2-84-001. Office of Research and
Development, Cincinnati, Ohio. Available from NTIS as No. PB84 177831.
U.S. Environmental Protection Agency. 1987. Construction Quality Control
and Post-Construction Performance Verification for the Gil son Road Hazardous
Waste Site Cutoff Wall. EPA/600/2-87/065. Available from NTIS as No. PB88
113295.
9
-------
APPENDIX A
SUPPLEMENTARY MATERIAL FOR
OVERVIEW OF THE WOOD PRESERVING INDUSTRY
Dr. Gary D. McGinnis, Mississippi State University
-------
EPA/600/2-88/055
September 1988
CHARACTERIZATION AND LABORATORY SOIL TREATABILITY
STUDIES FOR CREOSOTE AND PENTACHLOROPHENOL
SLUDGES AND CONTAMINATED SOIL
by
Gary D. McGinnis
Hamid Borazjani
Linda K. McFar!and
Daniel F. Pope
David A. Strobel
Mississippi Forest Products Utilization Laboratory
Mississippi State University
Mississippi State, Mississippi 39762
Project CR-811498
Project Officer
John E. Matthews
Robert S. Kerr Environmental Research Laboratory
P.O. Box 1198
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
Bwooucro IY
NATIONAL TECHNICAL
INFORMATION SERVICE
US, OtPAATMCMT OF COMMIKCE
SPRMGMUO. V*. 22161
-------
12
WOOD PRESERVING INDUSTRY
Introduction (Burden, 1984)
Wood preserving in the United States is a hundred-year-old
industry. Wood is treated under pressure in cylinders with one of four
types of preservatives: 1) creosote, 2) pentachlorophenol in petroleum,
3) water solutions of copper, chromium, and arsenic (CCA), and 4) fire
retardants.
The 1978 volume of wood commodities treated is shown in Table 1
(USDA, 1980).
Table 1. Volume of wood commodities treated in 1978.
Product Volume treated with
Creosote solutions Penta Inorganic salts3
1,000 cu. ft.
Crossties, switch
ties, and land-
scape ties
103,138
449
2,498
Poles
18,237
41,905
4,038
Crossarms
41
1,615
29
Piling
9,993
1,154
943
Lumber and
timbers
10,780
21,209
73,317
Fence posts
4,584
10,983
4,461
Other products
7,815
2,681
7,616
Total (1980)
154,587
79,996
92,903
aThe main inorganic salts are copper, chromium, and arsenic.
About 99% of the creosote solutions, 90% of the penta, and all of
the arsenical salts in the preceding tabulation are applied by pressure
methods in closed systems. A small amount of creosote and about 3.8
-------
13
million pounds of penta are applied by commercial thermal and dip
treatment methods in open tanks.
Basic Wood-Treating Process
The basic oil-preservative wood-treating cycle begins by placing
either seasoned or green wood into a pressure cylinder. If green
materials are used, they can be artificially seasoned in the cylinder
with steam and either oil preservative or hydrocarbon vapor. Then an
initial air pressure (vacuum or positive pressure) is introduced into
the system. Next the preservative is pumped into the cylinder and the
pressure increased until a predetermined liquid volume is absorbed into
the wood. The pressure is released and the preservative is pumped back
into the tanks. A final vacuum is applied to remove most of the free
liquid on the surface.
The organic preservative most used is coal tar creosote, a Dy-
product from the production of coke from coal. When coal tar is
distilled, the 200° to 400°C fractions are creosote. Creosote is
mostly aromatic single to multiple ring compounds. Over 200 different
components have been identified in creosote.
Fentachlorophenol dissolved in No. 2 fuel oil carrier is the second
most corrmon organic wood preservative. Technical grade PCP is about 85
to 90% pure PCP plus various levels of other chlorinated phenolic
compounds.
CHARACTERISTICS OF THE ORGANIC WOOD PRESERVATIVES
The two major organic wood preservatives used in the United States
are pentachlorophenol (PCP) and creosote.
-------
14
Technical-grade PCP used for treating wood contains 85 to 90% PCP.
The remaining materials in technical grade PCP are 2,3,4,6-
tetrachlorophenol (4 to 8%), "higher chlorophenols" (2 to 6%), and
dioxins and furans(0.1%). The tetrachlorophenol is added to PCP to
increase the rate of solubilization.
The other contaminants found in technical-grade PCP are formed
during manufacture. In the United States PCP is manufactured from
phenol by a catalytic chlorination process. During chlorination, the
temperature must be maintained above the melting point of the products
formed; this, it is felt, contributes to the side reaction that gives
rise to contaminants, including traces of trichlorophenol, chlorinated
dibenzo-p-dioxins, chlorinated dibenzofurans, chlorophenoxy phenols,
chlorodiphenyl ethers, chlorohydroxydiphenyl ethers, and traces of even
more complex reaction products of phenol. Chlorodibenzodioxins and
furans are the by-products about which there are the greatest concerns.
Analyses of PCP have revealed that the principal chlorodibenzodioxin and
chlorodibenzofuran contaminants are those containing six to eight
chlorines. The highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
has not been identified in any sample of PCP produced in the United
States that has been analyzed (USOA 1980). The composition of a sample
of commercial PCP and of a sample of purified PCP is given in Table 2.
A representative distribution of isomers is given in Table 3 (U.S. EPA
1978).
The physical properties of a compound play an important role in how
the compound behaves under different conditions. These properties
influence the mobility of a compound in air or water, its ability to
adsorb to surfaces, and its susceptibility to degradation. These
-------
15
Table 2. Comparison of composition of commercial grade and purified
grade pentachlorophenol (U.S. EPA 1978).
Component Analytical results
Commercial3 Purifiedb
(Oowicide 7) (Dowicide EC-7)
Pentachlorophenol
88.4%
89.8%
Tetrachlorophenol
4.4%
10.1%
Trichlorophenol
0.1%
0.1%
Chlorinated phenoxyphenols
6.2%
—
Octachlorodioxin
2500 ppm
15.0 ppm
Heptachlorodioxins
125 ppm
6.5 ppm
Hexachlorodioxins
4 ppm
1.0 ppm
Octachlorodibenzofuran
80 ppm
1.0 ppm
Heptachlorodibenzofurans
80 ppm
1.8 ppm
Hexachlorodibenzofurans
30 ppm
1.0 ppm
aSample 9522A.
^Technical grade PCP purified by distillation.
Table 3. Chlorodioxin isomer distributions in
commercial grade PCP (Dowicide 7)
and PCP-Na samples (Buser
1975, 1976).
Chlorodioxin
PCPa
PCP-Nab
(ppm)
(ppm)
1>2,3,6,7,9-ClgD
1
0.5
1,2,3,6,8,9-ClgD
3
1.6
1,2,3,6,7,8-ClgD
5
1.2
1,2,3,7,8,9-ClgO
0
0.1
1,2,3,4,6,7,9-C17D
63
16.0
1,2,3,4,6,7,8-Cl7D
171
22.0
1,2,3,4,6,7,8,9-Cl80
250
110.0
aDowicide 7 (corrmercial PCP).
bSodium salt of PCP.
-------
16
factors are important because they relate to the route and rate of
exposure by which a compound might be received by man or other
organisms. Some of the selected physical properties of pentachloro-
phenol are given in Table 4.
Pentachlorophenol is quite stable. It does not decompose when
heated at temperatures up to its boiling point for extended periods of
time. Pure PCP is considered to be rather inert chemically (Bevenue and
Beckman, 1967). The chlorinated ring structure tends to increase
stability, but the polar hydroxyl group tends to facilitate biological
degradation (Renberg, 1974). It is not subject to the easy oxidative
coupling or electrophilic substitution reactions common to most phenols.
All monovalent alkali metal salts of PCP are very soluble in water, but
the protonated (phenolic) form is virtually insoluble. Hence, transport
of PCP in water is related to the pH of the environment.
Pentachlorophenol is moderately volatile and a closed system should
be used when heating environmental samples or recoveries will be poor
(Bevenue and Beckman, 1967). By contrast to other chlorinated organic
compounds of low vapor pressure, PCP can be lost from soils by
volatilization (Briggs, 1975).
Creosote
The other major organic wood preservative used in the United States
is creosote. Creosote, in contrast to PCP, is a very complex mixture of
organic compounds produced from coal.
At least 200 chemical compounds have been identified in creosote.
Although the chemical composition of this material varies for reasons
discussed above, it is generally agreed that creosote contains several
-------
Table 4. Physical properties of PCP (Crosby 1981; Bevenue
et al. 1967).
Property Value
Empirical formula CgClgOH
Molecular weight 255.36
Melting point 190°C
Boiling point 293°C
Density 1.85 g/cc
pKA (25°) 4.70-4.80
Partition coefficient (Kp), 25°
Octanol-water 1760
Hexane-water 1.03 x 10°
Vapor pressure, Torr (mm hg]
0°C 1.7 x 10"5
20°C 1.7 x 10"}
50°C 3.1 x 10"3
100°C 0.14
200°C 25.6
300°C 758.4
Solubility in water (g/L)
0°C 0.005
20°C 0.014
30°C 0.020
S0°C 0.035
70°C 0.085
Solubility in organic solvents
(g/lOOg solvent)
in methanol 20°C 57
in methanol 30°C 65
in diethylether 20°C 53
in diethylether 30°C 60
in ethanol 20°C 47
in ethanol 30°C 52
in acetone 20°C 21
in acetone 30°C 33
in xylene 20°C 14
in xylene 30°C 17
in benzene 20°C 11
in benzene 30°C 14
in carbon tetrachloride 20°C 2
in carbon tetrachloride 30°C 3
-------
thousand different compounds which could be .identified with GC/MS. Most
of these are present in very small amounts. The major components
of a typical creosote of U.S. origin and one of German origin
are shown in Table 5. There are some rather striking differences
between the two types of creosote in the levels of particular polycylic
aromatic hydrocarbons and in the overall levels of total PAH's.
The greater part of the composition of creosote consists of neutral
fractions. Tar acids, such as phenol and the cresols, as well as such
tar bases as pyridenes, quinolines, and acridines, constitute a rather
small percentage of the total weight of creosote.
A schematic of the distillation processes is presented in Figure 1.
Creosote is a blend of the various distillates designed to impart
specific physical characteristics that meet standards of the American
Wood-Preservers' Association (AWPA).
Compared to the starting material, the yield of fractions that are
blended to make creosote ranges from 25 to 40%, depending upon the point
at which distillation is terminated. Both the yield and the chemical
and physical properties of the various fractions are influenced by the
characteristics of the coal from which the tar originates, the type of
equipment used in the distillation process, and the particular process
used.
There were 64 producers of coal tar in the United States in 1972
and 24 tar distillation plants producing creosote (U.S. EPA, 1975).
Because their chemical composition and properties are not uniform,
creosote and blends of creosote and coal-tar are normally described in
terms of their physical properties. American Wood-Preservers'
Association specifications for creosote for various uses are given in
-------
19
Table 5. Chemical composition of a United States and a German creosote.
— Percent of total—— -
Compound or component U.S. creosote3 German creosoteb
Naphthalene
3.0
7.3
Methyl naphthalene
2.1
4.2
Diphenyl dimethylnaphthalene
mm
3.2
Biphenyl
0.8
mm
Acenaphthene
9.0
4.1
D imethy1naphthalene
2.0
..
Diphenyloxide
3.4
Dibenzofuran
5.0
at tm
Fluorene-related compounds
10.0
9.6
Methyl fluorenes
3.0
Phenanthrene
21.0
12.6
Anthracene
2.0
mm
Carbazole
2.0
mm
Methylphenanthrene
3.0
5.4
Methyl anthracenes
4.0
mm
Fluoranthene
10.0
6.8
Pyrene
8.5
5.0
Benzofluorene
2.0
4.6
Chrysene
3.0
2.8
Total
90.4
69.0
®Lorenz and Gjovik, 1972.
"Becker, 1977.
-------
20
Coal Tar
L Chemical
Oil
Top-of-
Coiumn Oil
-Uncorrected
Creosote Oil
Heavy Oil
Figure 1, Principal cuts produced in coal-tar distillation.
-------
Table 6. Similar standards have been promulgated by the American
Society for Testing and Materials (ASTM) and the General Services
Administration (GSA). The principal differences among creosotes for the
three uses shown are in specific gravity and the fraction of the oil
distilled within various temperature ranges.
A comparison of physical properties of creosote and creosote/coal
tar mixtures as shown in Table 7 indicates much higher distillation
residue for coal tar. A list of the properties of some of the 16
priority pollutant PAH compounds found in creosote is given in Table 8
(Sims et al1987).
Another group of compounds which have been identified in creosote
and which are related to the PAH's are the azaarenes which make up
approximately 0.13% of creosote (Adams et al., 1984). These compounds
are polycyclic hydrocarbons containing nitrogen (e.g., quinoline and
acridine).
CHARACTERISTICS OF WOOD-PRESERVING WASTES
There are several sources of contamination at wood-treating sites.
During the treatment cycle, waste water with traces of preservative in
water is produced from several sources, from the live steaming of the
wood, from vapor drying or oil seasoning, from vacuum condensate, from
steam and oil leaks around the system, from cleanup, and from
contaminated rain water. Treatment of this plant water produces sludges
that are classified by EPA as K001, Hazardous Waste.
Prior to the environmental rules on wastewater discharge, the
treating plant wastewater effluent generally went directly to surface
drainage or a stream. A large number of the plants had sumps or ponds
-------
22
TableS • Physical properties of creosote and its fractions. (USDA 1980)
American Wood-Preservers' Association Standards
Pl-65*
P7-72
P13-65C
Water % volume
Xylene, insoluble, % by wt,
Specific gravity 38/15.5°C
Whole creosote
Fraction 235-315°C
Fraction 315-355°C
Residue above 355°C
Distillation, % by wt.
Up to 210°C
235°C
270°C
315°C
355°C
< 1.5
< 0.5
> 1
.050
> 1
.027
> 1
.095
Min.
Max.
2.0
12.0
20.0
40.0
45.0
65.0
65.0
82.0
< 1.0
< 0.5
> 1.060
Min. Max.
1.0
10.0
65.0
< 1.5
< 0.5
> 1.080
> 1.030
> 1.105
> 1,
,160
Min.
Max.
_ _
2.0
12.0
20 ..0
40.0
45.0
65.0
65.0
75.0
For land and fresh water use.
^ For brush or spray application.
For marine (coastal water) use.
-------
Table 7. American Wood-Preservers' Association specifications for creosote-coal tar
solutions.3
Grade
A B C D
Composition
Creosote
Coal tar
100%
<80
<70
<60
>50
Water (% by volume)
Xylene, insol. (% by weight)
Coke residue (% by weight)
Specific gravity 38/15.5°C
Whole oil
235-315°C
315-355°C
Residue
0.99
1.102
1.054
1.133
>3.0
>2.0
>5.0
1.06-1.11
1.025
1.085
>3.0
>3.0
>7.0
1.07-1.12
1.025
1.085
>3.0
>3.5
>9.0
1.08-1.13
1.025
1.085
>3.0
>4.0
>11.0
1.09-1.14
1.025
1.085
Distillation
To 210°C
To 235°C
To 270°C
To 315°C
To 355°C
Residue
1.87
6.89
19.39
49.8
72.58
26.67
5
25
36
60
5
25
34
56
5
25
32
52
5
25
30
48
aLoren and Gjovik, 1972.
-------
Table 8. Properties of 16 priority pollutant PAH compounds. (Sims 1987).
Aqueous ^ Melting
Molecular Solubility Point
Weight mg/1 °C
Vapor
Boiling pressure
Point* 9 20°C
°C torr
Log K
ow
Length of
Holecule
A0
Roc
1. Two Rings
Naphthalene
128
31,700
80
218 4.92xl0-2 3.37 8.0 1,300*
2. Three Rings
Acenaphthylene
Acenaphthene
Fluorene
Anthracene
Phenanthrene'
JJ
152
154
166
178
178
3,470
3,930
92
96
73 216
265 2.9xl0-2 4.07
279 2.0x10-2 4.33
1,980 116 293 1.3x10-2 4.18
340 1.96xl0'4 4.45 10.5
1,290 101 340 6.B0xl0'4 4.46 9.5
2,600*
23,000*
-------
Table 8. (continued)
Aqueous
Holecular Solubility
Weight mg/1
3. four Rings
Fluoranthene
Pyrene
Be(u(a)anthracene
Chrysene
4. Five Rings
0enzo(b)fluoranthene
Benzo(k)fluoranthene
202
202
228
228
252
^ 252
260
135
14
1.2
0.55
Vapor
Melting Doiling pressure length of
Point Point* 0 20°C Holecule
°C °C torr Log Kow* A° Koc
84,G0Qf
111 -- 6.0x10"® 5.33 9.4
149 360 6.85x10"' 5.32 9.5 62,700?
158 400 5.0x10*9 5.61 11.8
255 - 6.3x10"' 5.61 11.8
167 -- 5.0x10"' 6.57
217 480 5.0x10"' 6.84
PO
en
-------
Table 8. (continued)
Molecular
Weight
Aqueous
Solubility*
mg/1
Melting
Point
°C
Vapor
Coiling pressure
Point* § 20°C
°C torr
Log Kow
Length of
Holecule
AO
Koc
Benzo{a)pyrene
252
3.8
179
496 5-OxlO'7
6.04
4,510,651
0ibenz(a ,h)anthracene
OrY55) 2,8
2.49
262
-- l.OxlO10
5.97
13.5
2,029,000*
5. Six Rings
Benzo(g,h,i)perylene
(55^ "6
0.26
222
-- l.OxlO*10
7.23
1ndeno(1,2,3-Cd)pyrene
276
62
163
-- l.OxlO'10
7.66
biros and Overcash (1983).
*Karickhoff el al. (1979).
'Means et al. (1980) (mean value is reported).
ro
cn
-------
to trap the heavy oil residuals before discharging to a creek or to the
publicly-owned treating works (PQTW). Ponds ranged from less than an
acre to eight acres. Normally the ponds were lined with the local
soils. Typical constituents present in creosote wastewater are given in
Table 9.
Normal wood-treatment operations create additional preservative
waste. Treating tanks and cylinders have to be cleaned periodically to
maintain quality standards. In the past these preservative sludges were
used as fuel or for road paving or were buried at the facility.
Preservative-contaminated soil is another source of environmental
concern. Treated material is withdrawn from the cylinder and moved by
rails to storage areas. During transportation the preservative drips
from the treated wood onto the soil along the track. The areas around
storage, treating, and unloading tanks have had minor preservative
spillage from broken pipes, bleeding of treated wood, etc. These areas
can.be rather large, especially in the older railroad and pole plants.
DECOMPOSITION/IMMOBILIZATION OF PCP AND CREOSOTE COMPONENTS IN SOIL
Pentachlorophenol
A large number of studies on biodegradation of PCP in soil have
been done. The sequence of reactions that have been shown to occur is
summarized in Figure 2. In soil, PCP undergoes a reversible methylation
reaction to form pentachloroanisole, but this reaction apparently is not
part of the main decomposition pathway. The main route for
decomposition is not through the methyl derivative, but through PCP
-------
Table 9. Daily discharge of creosote wastewater pollutants by the wood-
oreservino industry (USDA 1980).
Creosote
Composition of
Allowable Discharge
Component
Whole Creosote
1977
1983
Percent
Pounds/day
Naphthalene
3.0
5.0
1.4
2-Methylnaphthalene
1.2
2.0
.6
1-Methylnaphthalene
.9
1.5
.4
Biphenyl
.8
1.3
.4
Dimethylnaphthalenes
2.0
3.4
1.0
Acenaphthene
9.0
15.1
4.3
Dibenzofuran
5.0
8.4
2.4
Fluorene
10.0
16.8
4.8
Methylfluorenes
3.0
5.0
1.4
Phenanthrene
21.0
35.3
10.0
Anthracene
2.0
3.4
1.0
Carbazole
2.0
3.4
1.0
Methylphenanthrenes
3.0
5.0
1.4
Methylanthracenes
4.0
6.7
1.9
Fluoranthene
10.0
16.8
4.8
Pyrene
8.5
14.2
4.0
Benzofluorenes
2.0
3.4
1.0
Chrysene
3.0
5.0
1.4
Discharges are based on a flow rate of 5,000 gal/day per plant, 90 plants, and
discharge limitations on oil and grease of 45 mg/liter in 1977 and 13 mg/liter
in 1983.
-------
OH
CIv^yCI
CI
OCH,
ci-*^Aci
ci
Esterification
Reaction
OH
CIn^X^ci dechlorination
Cl^y^CI
CI
C02 + CI0
Hooey,,
CI
mono-.di-,
-*>- and
trichlorophenols
Oxidative
Process
OH
H02sjfc'
CI
Figure 2. Proposed route for decomposition of pentachlorophenol.
-------
30
(Kaufman, 1978; Matsunaka and Kuwatsuka, 1975). The route of
decomposition involves dechlorination leading to a series of partial
dechlorinated products, such as 2,3,5,6-tetrachlorophenol.
The second step in the decomposition reaction involves an oxidation
step to form substituted hydroquinones or catechols, such as 2,3,4,"5-
tetrachlorocatechol. The oxidation product then undergoes ring
cleavage, ultimately forming C02 and an inorganic chloride ion.
Mobility, persistence, and fate of PCP in soils depend on physical
and chemical characteristics of the soil as well as the prevailing
microbial population.
Hilton and Yuen (1963) compared soil adsorption of PCP to the soil
adsorption of a number of substituted urea herbicides. They found that
the adsorption of PCP was the highest of all compounds studied.
Choi and Aomine (1972, 1974, 1974a) studied the interaction of PCP
and soil in detail. Adsorption and/or precipitation of PCP occurred to
some extent on all soils tested. Choi and Aomine (1974) concluded in a
study of 13 soils that adsorption of PCP depended primarily on the pH of
the system. The more acid the soil, the more complete was the "apparent
adsorption" of PCP. Different mechanisms of adsorption dominate at
different pH values. It should be noted that PCP is an acid which forms
a salt at the higher pH's. In the salt form, PCP would be more soluble
in water but also more polar. In acid clays "apparent adsorption"
involved the adsorption on colloids, and precipitation in the micelle
and in the external liquid phase. Organic matter content of soils is
important to adsorption of PCP at all pH values. Soil containing humus
always adsorbs more PCP than soil treated with to remove organic
-------
31
matter. Later investigations led to the conclusion that adsorption of
PCP by humus is important when the concentration is low, but at higher
concentrations the inorganic fraction increases in importance.
Three of four allophanic soils showed a significant increase in PCP
adsorption at higher temperatures, while the fourth soil showed a
decrease (Choi and Aomine, 1974a). The difference between the three
soils and the fourth soil could be explained by assuming that andosols
chiefly adsorb PCP as anions; whereas, the major factor influencing PCP
adsorption by the fourth soil, showing a decrease with increasing
temperature, is due to Van der Waal's force. Decreasing the
concentration of chlorides or sulfate ions also increases the adsorption
of PCP to soil. These results indicate the occurrence of competition
between inorganic anions and PCP anions for adsorption sites on the soil
colloid.
The persistence of PCP in soil depends on a number of environmental
factors. Young and Carroll (1951) noted that PCP degradation was
optimum when the moisture content of soil was near saturation.
Kuwatsuka and Igarashi (1975) reported that the degradation of PCP is
faster under flooded conditions than under upland conditions. Loustalot
and Ferrer (1950) found that the sodium salt of PCP was relatively
stable in air-dried soils, persisted for 2 months in soil of medium
moisture content, and for 1 month in water-saturated soil. Although the
rates of degradation may be maximized at the higher moisture values,
these conditions would not be suitable for land treatment because of the
increased potential for migration.
-------
There are several factors in soil which affect the persistence of
PCP. PCP is broken down slower in heavy clay than in sandy or sandy
clay soils (Loustalot and Ferrer, 1950). This could be due to factors
in the soil or to a slower oxygen transfer in the soil. An extensive
study of the soil variables affecting the rate of degradation of PCP was
carried out by Kuwatsuka and Igarashi (1975). The rate was correlated
with clay mineral composition, free iron content, phosphate adsorption
coefficients and cation exchange capacity of the soil, while the
greatest effect was correlated with organic matter. According to these
authors, little or no correlation could be found with soil texture, clay
content, degree of base saturation, soil pH, and available phosphorus.
The preponderance of information indicates that microbial activity
plays an important part in the degradation of PCP in soil. PCP decays
more rapidly when the ambient temperature approaches the optimum value
for microbiological activity (Young and Carroll, 1951). Ide et al.
(1972) found no decay in sterilized soil samples. These factors suggest
that microorganisms play an important role in PCP degradation (Kuwatsuka
and Igarashi, 1975; Young and Carroll, 1951). Kuwatsuka and Igarashi
(1975) studied degradation of PCP in soils collected from flooded and
upland areas. Upland soils degraded PCP more rapidly in the laboratory
when studied in the aerated condition, while soils obtained from flood
conditions degraded PCP more rapidly when tested in the flooded stage.
Thus, PCP-degrading microorganisms present in the soil survived the
transfer to the laboratory and were most active when placed in an
environment to which they were adapted.
-------
A summary of the literature values for the persistence of PCP in
soil is presented in Table 10. The persistence ranged between 22 days
and 5 years. The 5-year value obtained by Hetrick (1952) was from dry
soil sealed in a jar and probably does not represent a realistic
evaluation of the environmental half-life. Thus, PCP can be considered
moderately persistent under most conditions.
Numerous degradation products have been isolated from PCP-treated
soil. Ide et al. (1972) identified 2,3,4,5-, 2,3,5,6-, 2,3,4,6-tetra-
chlorophenol; 2,4,5- and 2,3,5-trichlorophenol; 3,4- and
3,5-dichlorophenol; and 3-chlorophenol. Similar products were obtained
by Kuwatsuka and Igarashi (1975), who also identified pentachloroanisole
as a PCP degradation product. This reaction is reversible and
pentachloroanisole can subsequently degrade back to PCP. Demethylation
and methylation of phenolic groups in biological systems are well known
(Williams, 1959). Ide et al. (1972) found 2,3,4,5-, 2,3,5,6- and
2,3,4,6-tetrach1oroaniso1es; 2,3,5-trichloroanisole; 3,4- and
3,5-dichloroanisoles; and 3-chloroanisole as methylated products of PCP
in incubated soil. Based on the results obtained from these
investigations, Matsunaka and Kuwatsuka (1975) proposed the soil
degradation pathway shown in Figure 2. An excellent review of the
parameters important for degradation of pentachlorophenol in soil can be
found in a review by Kaufman (1978).
Many types of bacteria and fungi are capable of degrading
pentachlorophenol, including Pseudomonas. Aspergillus, Trichoderma, and
Flavobacterium. Chu and Kirsch (1972) isolated a bacterial culture by
continuous flow enrichment that was capable of metabolizing PCP as a
sole source of organic carbon. The morphological and physiological
-------
Table 10. Degradation of pentachlorophenol in soil (USDA 1980).
Degradation
parameter
Soil type
Special
conditions
Time
90% degradation
Arable layer
in rice fields
(11 soils)
60% water
25% water
Approx. 50 days
Approx. 30 days
90% degradation
Complete
Effect on
growth of
corn and
cucumbers
90% degradation
Forest red-
yellow soil
sublayer
Wooster silt
loam
Dry soil
Fertile sandy
loam
Mature paddy
soi 1
60% water
25% water
7.5 kg/ha
penta, optimum
conditions for
microbial growth
Sealed in air-
tight container
Air-dried
Medium water
Water saturated
Low organic
content
No degradation
in 50 days
Approx. 22 days
> 5 years
> 2 months
2 months
1 month
1 month
-------
Table 10. (continued)
Degradation
parameter
Soil type
Special
conditions
Time
Complete
degradation
Complete
degrada t ion
Complete
degradation
Dunkirk silt
loam
Paddy soil
Warm, moist
soi 1
98% degradation Permeable soil
Aerated,
aqueous soil
suspension
Soil perfusion
Composted with
sludge from
wood-treati ng
plant
Approx. 72 days
21 days
> 12 months
205 days
-------
characteristics of the organisms suggest a relationship to the
saprophytic coryneform bacteria. Chu and Kirsch (1973) established that
the organism was responsive to enzyme induction with PCP as the inducer.
Lesser induction occurred with 2,4,6-trichlorophenol. The degradation
products resulting from the metabolism of PCP by this organism were not
characterized.
Kirsch and Etzel (1973) derived a microbial population capable of
rapid PCP degradation from a soil sample obtained on the grounds of a
wood products manufacturer. When fully acclimated, the populations were
dosed with 100 mg/liter of PCP and 68% of the PCP was degraded in 24
hours. These cultures were most effective when the PCP was the sole
source of carbon.
Watanable (1973) reported penta degradation in soil samples
perfused with 40 mg/liter PCP. Bacteria isolates capable of PCP
decomposition were derived from a soil perfusion enrichment culture.
Degradation and complete dechlorination occurred after 2 to 3 weeks of
incubation. The bacterium was characterized as a Pseudomonas sp. or an
organism from a closely related genus. Tetrachlorodihydroxyphenols and
their monoethyl ethers were tentatively identified as a metabolic
product of PCP by Aspergillus sp. (Cserjesi, 1972). A soil bacterium
isolated by Suzuki ana Nose (1971) was capable of degrading PCP. The
major metabolites were pentachloroanisole and dimethyl ether; a minor
metabolite was tetrachlorohydroquinone.
More recently Edgehill (Edgehill et al., 1984) isolated a soil
bacterium capable of utilizing PCP as a sole source of carbon. The
organism was a member of the coryneform group of bacteria, probably the
genus Arthrobacter.
-------
It is clear that bacteria and fungi capable of degrading PCP exist
in nature. However, the number of species and their population may be
limited. In most cases where rapid degradation of PCP by microorganisms
has been demonstrated, the source of inoculum was from areas where PCP
had been used for a long time.
Creosote Components
The major components of creosote are the polycyclic aromatic
hydrocarbons (PAH's) with trace amounts of phenols and azaarenes. A
wide range of soil organisms, including bacteria, fungi, cyanobacteria
(blue-green algae), and eukaryotic algae, have been shown to have the
enzymatic capacity to oxidize PAH's. Prokaryotic organisms, bacteria,
and cyanobacteria use different biodegradation pathways than the
eukaryotes, fungi, and algae, but all involve molecular oxygen.
Tausson (1950) first demonstrated that several PAH's, including
naphthalene, anthracene, and phenanthrene, can serve as substrates for
some soil organisms and are "completely" metabolized. Groenewegen and
Stolp (1981) isolated microorganisms that can use the compounds
mentioned above as their sole C source. However, they could show
degradation of some of the less-water-soluble PAH's, such as
benz(a)anthracene and benzo(a)pyrene (BaP), only when the PAH's were
mixed with soil, water, and a substance to stimulate growth of
oxygenase-active organisms. Shabad et al. (1971) discussed a number of
experiments that demonstrated bacterial degradation of BaP in soil.
They reported 50-80% destruction of BaP over a period of "several" days
by bacteria in soil contaminated with shale oil containing high
concentrations (up to 20,000 yg/kg) of BaP. Shabad et al. also found
-------
that the capacity of bacteria to degrade BaP increased with BaP content
in the soil and that microflora of soil contaminated with BaP were more
active in metabolizing BaP than those in "clean" soil. Cerniglia and
Crow (1981) demonstrated the metabolism of naphthalene, biphenyl, and
BaP by a number of different species of yeast, some of which were
previously reported in high numbers in oil-polluted soils. Cerniglia
and Gibson (1979) reported the degradation of BaP by a filamentous
fungus, and Dodge and Gibson (1980) demonstrated the degradation of
benz(a)anthracene by the same fungal species.
Cerniglia and Gibson (1979) reported that the metabolites formed
during the degradation of BaP by a fungus were very similar to those
formed during BaP metabolism in mammals. Such metabolites are probably
responsible for the carcinogenicity of BaP. However, Shabad et al.
(1971) reported that extracts of a medium containing BaP were less
carcinogenic to mice (Mus spp.) after microbial degradation than before
degradation. A more complete review of earlier research (before 1970)
on microbial oxidation of PAH's was presented by Gibson (1972).
Biochemical pathways for the degradation of a number of PAH's by soil
microorganisms have been proposed by Fernley and Evans (1958), Evans et
al. (1965) and Gibson et al. (1975). One proposed mechanism for the
reaction is shown in Figure 3.
Generally, rates of degradation for PAH compounds decrease as the
molecular weight increases; rates of degradation are faster in soil than
water; and overall rates of degradation are faster where there is an
acclimated bacteria population (Herbes et al., 1980). These
observations had also been made earlier (Sims and Overcash, 1983).
-------
Anthracene
1,2-Dihydro-1,2-
dihydroxy-anthracene
^\^COOH
Salicylic Acid
Catechol
Figure 3. Proposed mechanism for the microbiological
degradation of anthracene (Rogoff 1961).
-------
40
Compounds such as naphthalene, phenanthrene, and anthracene, which
are readily metabolized, are relatively water soluble, while persistent
PAH's, such as chrysene and benzo(a)pyrene, have a lower water
solubility (Table 11). Exceptions exist with pyrene and fluoranthene in
that these compounds are more soluble than anthracene and yet have not
been found by some researchers (Groenewegen and Stolp, 1981) to be
appreciably metabolized by soil microorganisms. Other factors that may
affect the persistence of PAH compounds are insufficient bacterial
membrane permeability to the compounds, lack of enzyme specificity and
lack of aerobic conditions (Overcash and Pal, 1979).
Two sets of studies were recently completed by Bulman et al. (1985)
to assess PAH loss from soil. In the first, a mixture containing levels
of 5 and 50 mg/kg of eight PAH's [naphthalene, phenanthrene, anthracene,
fluoranthene, pyrene, benzo(a)anthracene, chrysene and benzo(a)pyrene]
was added to soil and the concentration of each compound was monitored
with time. In the second experiment, *4C labeled benzo(a)pyrene and
anthracene were added to unacclimated agriculture soil in biometer
flasks. The distribution of 14C as volatile, adsorbed, and degraded
products was determined in sterilized and biologically active soil. In
the first set of studies, naphthalene, phenanthrene, anthracene, pyrene,
and fluoranthene disappeared rapidly from soil during an initial period
of 200 days or less. A loss of 94 to 98 percent occurred during this
period and approximated first-order kinetics, in some cases following a
lag period. With the exception of anthracene, the first-order kinetic
rate constants were the same for 5 and 50 mg*kg"l additions of PAH.
Following the initial period, the remaining 2-6 percent of the added PAH
-------
;able 11. Kinetic parameters describing rates of degradation of PAH and phenolic compounds in soil
systems (Sims and Overcash 1983, ERT 1985b).
Substance
Initial
Concentration
(ug/g soil)
k
(day"1)
1/2 Life
(days)
Reference
Phenol
500
0.693
1.0
Medvedev & Davidov (1972)
Phenol
500
0.315*
2.2*
Medvedev & Davidov (1972)
2,4-dimethylphenol
500
0.35-0.69
1-2
Medvedev & Davidov (1972)
4,6-dinitro-o-cresol
--
0.023
30
Versar, Inc. (1979)
2,4-dinitrophenol
5-50
0.025
28
Overcash et al. (1982)
2,4-dinitrophenol
20-25
0.099-0.23
3-7
Sudharkar-Barik &
Sethunathan (1978)
4-nitrophenol
—
0.043
16
Verschuerer (1977)
Pentachloropheno!
--
0.018
28
Murthy et al. (1979)
Naphthalene
7
5.78
0.12
Herbes & Schwall (1978)
Naphthalene
7
0.005*
125*
Herbes & Schwall (1978)
Naphthalene
7
0.173
4+
Herbes t> Schwall (1978)
Acenaphthylene
0.57
0.039
18
Sims (1982)
Acenaphthylene
57
0.035
20
Sims (1982)
Anthracene
0.041
0.019
36
Sims (1982)
Anthracene
41
0.017
42
Sims (1982)
Phenanthrene
2.1
0.027
26
Groenewegen and Stolp (1976)
Phenanthrene
25,000
0.277
2.5+
Sisler and Zobell (1947)
Benz(a)anthracene
0.12
0.046*
15.2*
Herbes & Schwall (1978)
Benz(a)anthracene
3.5
0.007
102
Groenewegen & Stolp (1976)
Benz(a)anthracene
20.8
0.003
231
Gardner et al. (1979)
Benz(a)anthracene
25.8
0.005
133
Gardner et al. (1979)
Benz(a)anthracene
17.2
0.008
199
Gardner et al. (1979)
8enz(a)anthracene
22.1
0.006
110
Gardner et al. (1979)
Benz(a)anthracene
42.6
0.003
252
Gardner et al. (1979)
-------
Table 11* (continued)
"' ' ' ' 1 ..... - ¦ ¦ ¦ 1 ' ¦ - ¦ ¦ " ¦ . ¦ 1 ¦
Initial
Concentration
k
1/2 Life
Substance
(ng/g soil)
(day"1)
(days)
Reference
Benz(a)anthracene
72.8
0.004
196
Gardner et al. (1979)
Benz(a)anthracene
0.07
0.005
134
Sims (1982)
Benz(a)anthracene
0.10
0.005
142
Sims (1982)
Benz(a)anthracene
0.15
0.005
154
Sims (1982)
Benz(a)anthracene
7
0.016
43
Sims (1982)
Fluoranthene
3.9
0.016
44
Groenewegen and Stolp (1976)
Fluoranthene
18.8
0.004
182
Gardner et al. (1979)
Fluoranthene
23.0
0.007
105
Gardner et al. (1979)
Fluoranthene
16.5
0.005
143
Gardner et al. (1979)
Fluoranthene
20.9
0.006
109
Gardner et al. (1979)
Fluoranthene
44.5
0.004
175
Gardner et al. (1979)
Fluoranthene
72.8
0.005
133
Gardner et al. (1979)
Pyrene
3.1
0.020
35
Groenewegen and Stolp (1976)
Pyrene
500
0.067
10.5
Medvedev and Davidov (1972)
Pyrene
5
0.231
3
Medvedev and Davidov (1972)
Chrysene
4.4
0
-
Groenewegen and Stolp (1976)
Chrysene
500
0.067
10.5
Medvedev and Davidov (1972)
Chrysene
5
0.126
5.5
50*
Medvedev and Davidov (1972)
Benz(a)pyrene
0.048
0.014
Herbes and Schwall (1978)
Benz(a)pyrene
0.01
0.001
694*
Herbes and Schwall (1978)
Benz(a)pyrene
3.4
0.012
57
Groenewegen and Stolp (1976)
Benz(a)pyrene
9.5
0.002
294
Gardner et al. (1979)
Benz(a)pyrene
12.3
0.005
147
Gardner et al. (1979)
Benz(a)pyrene
7.6
0.003
264
Gardner et al. (1979)
Benz(a)pyrene
17.0
0.002
420
Gardner et al. (1979)
Benz(ajpyrene
32.6
0.004
175
Gardner et al. (1979)
4^
PO
-------
Table 11. (continued)
Initial
Concentration k 1/2 Life
Substance (pg/gsoil) (day-1) (days) Reference
Benz(a)pyrene
Benz(a)pyrene
8enz(a)pyrene
Benz(ajpyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz{a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
Benz(a)pyrene
0ibenz(a,h)anthracene
Dibenz(a,h)anthracene
1.0
0.347
2+
0.515
0.347
2+
0.00135
0.139
5+
0.0094
0.002
406*
0.545
0.011
66*
28.5
0.019
37*
29.2
0
--
100
0.018
39+
19.5
0.099
7+
19.5
0.139
5+
19.5
0.231
3+
130.6
0.173
4*
130.6
0.116
6+
700
0.033
21+
000
0.039
18+
Shabad et
Shabad et
Shabad et
Shabad et
Shabad et
Shabad et
Shabad et
Sims et al
Sims et al
Sims et al
Sims et al
Sims et al
Sims et al
Sims et al
Sisler and
al. (1971)
al. (1971)
al. (1971)
al. (1971)
al. (1971)
al. (1971)
al. (1971)
. (1937)
. (1987)
. (1987)
. (1987)
. (1987)
. (1987)
. (1987)
Zobell (1947)
*Low temperature (<15°C)
+High temperature (>25°C)
CO
-------
44
was lost at a much reduced rate, and the first-order rate constants
tended to be higher with the 50 mg'kg"1 addition than the 5 mg'kg"1
addition of PAH.
Losses of only 22 to 88 percent were observed for
benzo(a)anthracene, chrysene, and benzo(a)pyrene, and only one kinetic
period was identified within the 400-day incubation period. With
chrysene, the first-order kinetic rate constants were the same at the 5
and 50 mg*kg"^ levels of addition; however, for benzo(a)anthracene and
benzo(a)pyrene the rate constants differed. The disappearance of
benzo(a)anthracene approximated first-order kinetics; however, a zero-
order kinetics was found for the disappearance of benzo(a)pyrene and
chrysene.
The mechanisms of disappearance of anthracene and benzo(a)pyrene
were assessed in a second set of studies using *4C labeling. The
results indicated that biological activity was responsible for some of
the loss of anthracene from soil; however, binding to soil solids and
volatilization (either as anthracene or as metabolites) were identified
as the major loss mechanisms. Identification of loss mechanisms for
benzo(a)pyrene was less successful due to the small amount of
benzo(a)pyrene that disappeared during the incubation period. Binding
of benzo(a)pyrene to soil solids appeared to be the major mechanism
involved, while microbial transformation of the compound was minimal.
Tortensson and Stenstrom (1985) have cautioned, however, that an
indirect measurement of mineralization such as liberated ^C02 from a
14C-labeled compound may not always be reliable. They recommend that
the rate of transformation of a substance be defined by direct
-------
45
measurement of its disappearance. Liberation of labeled CO2 may not be
concurrent with transformation because transformed compounds may not be
further degraded to labeled C02 during the time frame of the study.
Some PAH's with more than four rings are not known to be utilized
as a sole carbon source but have been reported to be co-metabolized with
other organic compounds. This process involves the concurrent
metabolism of a compound that a microorganism is unable to use as a sole
source of energy along with metabolism of a carbon source capable of
sustaining growth. In a study by McKenna and Heath (1976), the
co-metabolism of refractory PAH compounds in the presence of two- and
three-ring PAH compounds was investigated. The degradation of pyrene,
3,4-benzpyrene, 1,2-benzanthracene, and 1,2,5,6-dibenzanthracene in the
presence and in the absence of phenanthrene was measured. Separate
cultures of Flavobacterium and Pseudomonas were maintained in the
presence of each of the PAH compounds. Both Flavobacterium and
Pseudomonas exhibited negligible utilization of the refractory PAH
compounds in the absence of phenanthrene. However, Flavobacterium, in
the presence of phenanthrene, was able to significantly degrade all four
test compounds. Co-metabolism by Pseudomonas was not observed. In a
similar experiment PAH compound degradation by a mixed culture was
measured. For each PAH compound studied, one container of inoculum
received naphthalene as a growth substrate while a second container
received phenanthrene as a growth substrate. Cometabolism of pyrene,
1,2-benzanthracene, 3,4-benzpyrene, and 1,2,5,6-dibenzanthracene by the
mixed culture was exhibited in the presence of either naphthalene or
phenanthrene.
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46
The fate of PAH compounds in terrestrial systems has been reviewed
by Sims and Overcash (1983), Edwards (1983), and Cerniglia (1984).
These reviews present additional information on PAH degradation.
The types of phenols present in creosote in general are more
readily degraded than PAH's or PCP. The effect of phenols on soil
microorganisms is dependent on the soil concentration or amount added
(Overcash and Pal, 1979). At low doses (0.01-0.1 percent of soil
weight), the phenol serves as an available substrate, and there is an
increase in microbial numbers. As the dose level is increased (0.1-1.0
percent of soil weight), an increasingly strong inhibitory or
sterilizing effect is noted. At these levels, a partial sterilization
occurs in which there is a depression in microbial numbers, but not a
complete die-off. After a period of time, microbes adapt or phenol is
lost through sorptive inactivation or volatilization and a regrowth of
population occurs.
BIOACCUMULATION/T0XICITY OF PCP AND CREOSOTE
Plant/Animal Uptake of PCP
Information on the uptake and translocation of PCP by plants is
limited, and there is no information on the metabolism of PCP by plants.
Jaworski (1955) found less than 0.01 mg/kg PCP in cottonseed oil of
field-grown plants sprayed with ^C-PCP. Similarly, Miller and
Aboul-Ela (1969) could not detect PCP in cottonseed kernels of open
bolls on sprayed plants. However, in contrast to Jaworski (1955), they
found some translocation of PCP or a possible metabolite within the
plants. PCP residues definitely existed in seed from bolls that were
closed at the time of treatment. Miller and Aboul-Ela (1969) also
-------
47
observed the movement of ^C-labeled PCP in the first two leaves of
cotton within 1 hour of treatment. After 8 hours, radioactivity was
distributed through all the veins of treated leaves, but there was no
movement of radioactivity out of the treated leaves even after 8 days.
Hilton et al. (1970) studied the distribution of radioactivity in
sugar cane following either foliage or root application of ^C-PCP. With
leaf application, 100% of the radioactivity was found in the treated
leaf after 2 weeks. After 8 weeks, 84% of the activity was in the
treated leaf with minor amounts in all plant parts except roots. Root
application was studied by growing plants in a nutrient solution
containing ^C-PCP for 4 weeks. Approximately 90% of the original
radioactivity was recovered from the plants after 4 weeks, with over 99%
found in the root system.
Uptake of PCP by animals can occur by inhalation, oral ingestion
(including consumption of PCP-contaminated food and licking or chewing
treated wood) and dermal absorption by direct contact with treated wood.
There is some evidence that PCP may be a metabolic product of other
environmental contaminants, but the significance of this source is not
known. Koss and Koransky (1978) demonstrated the formation of PCP from
hexachlorobenzene in rats, mice, hens, and trout. Hexachlorobenzene
occurs widely in the environment, and low-level residues are frequently
encountered in animal tissues. The rate of PCP formation from
hexachlorobenzene is slow compared to the rate of PCP elimination.
Thus, the levels of hexachlorobenzene encountered in tissues are not
sufficient to account for the levels of PCP generally found.
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48
Many phenols undergo conjugation reactions in animals (Williams,
1959). These reactions include the formation of glucuronides, ethereal
sulphates, and monoesters of sulfuric acid. Some PCP is excreted
unchanged, and the amount that is metabolized or conjugated depends on
the species.
Approximately 40% of the *4C-labeled PCP given to mice and rats
was excreted unchanged in the urine (Ahlborg et al., 1974). 14C-
tetrachlorohydroquinone accounted for 5% of the excreted radioactivity
in rats and 24% in mice. Larsen et al. (1972) found that 50% of the
radioactivity of orally administered *4C-PCP was excreted in the urine
of rats in 24 hours and 68% was excreted in 10 days. Between 9 and 13%
was excreted in the feces. Tissue analysis showed small amounts of
activity in all tissues, with the highest level in liver, kidneys, and
blood. In blood, 99% of the radioactivity was in the serum. A
two-compartment urinary excretion pattern was proposed that had a
10-hour half-life for the first 2 days, followed by a 102-day half-life.
Braun et al. (1976) studied the pharmacokinetics and metabolism of
PCP in rats and monkeys. Excretion of from the labeled PCP was
mainly through the urine in both species. In the monkeys, only PCP was
found; while in rats, PCP, tetrachlorohydroquinone, and the glucuronide
conjugate of PCP were found. Residues were high in liver, kidneys, and
blood, thus agreeing with Larsen et al. (1972). It was suggested that
there was reversible binding of PCP to blood proteins. The half-life
ranged from 13 to 17 hours in rats and from 72 to 84 hours in monkeys.
This work failed to confirm the presence of the long half-life
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49
compartment suggested by. Larsen et al. (1972). The short half-lives of
PCP suggest that there will be no buildup of residues to a toxic level
with continuing intake of PCP.
Toxic Effects of PCP
The widespread use of PCP as an antimicrobial agent and the
likelihood of commercial products being contaminated with certain highly
toxic polychlorinated dibenzo-p-dioxins and dibenzofurans necessitate a
review of the toxicological information currently available. Although
this review is primarily concerned with data on PCP per se,
available data on commercial samples are included for comparative
purposes.
Oral Toxicity—The LD50 for PCP in male rats has been reported as
78 mg/kg (Deichmann et al., 1942), 90 mg/kg (Gabrilevskaya and Laskina,
1964), 146 mg/kg and 205 mg/kg, the last being Dowicide EC-7 (USDA,
1980). For the female rat, it was 135 mg/kg (Dow Chemical Co. Summary,
1969) and 175 mg/kg (EC-7) (Gaines, 1969).
The LD50 for mice was reported as 130 +_ 9.5 mg/kg (Pleskova and
Bencze, 1959); for rabbits, 100-130 mg/kg (Deichmann et al., 1942); for
guinea pigs, 250 mg/kg (Gabrilevskaya and Laskina, 1964); and for swine,
120 mg/kg (Harrison, 1959). Oreisbach (1963) has estimated an LDgg dose
for man to be as low as 29 mg/kg.
These data suggest that PCP has moderate acute oral toxicity, but
that the ID5Q value may vary with the quality and quantity of
contaminants. Man appears to be more susceptible than the rodent and
the female to be more susceptible than the male.
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50
Skin Absorption—When PCP in an organic solvent was applied to
rabbit skin under occlusion for 24 hours, 200 mg/kg was lethal, but 100
mg/kg and 50mg/kg were not (Dow 1969). The LD50 for rats has been
reported as 96 mg/kg, 105 mg/kg, and 320 mg/kg (Demidenko, 1966; Noakes
and Sanderson, 1969; Gaines, 1969) and that for mice as 261 + 39 mg/kg
(Pleskova and Bencze, 1959).
Subcutaneous Injection—The LD^q for rats was 100 mg/kg, for
rabbits 70 mg/kg (5% in olive oil) (Deichmann et al., 1942), and for
mice 63 +_ 3.2 mg/kg (Pleskova and Bencze, 1959).
Intravenous Injection—The lowest dose of PCP reported to kill
rabbits was 22 mg/kg (Kehoe et al., 1939) when it was instilled as a 1%
aqueous sodium pentachlorophenate.
Inhalation—Exposure to 5 mg/1 dust for one hour did not kill male
and female rats (Reichhold Chemicals, 1974). Demidenko (1969) reported
the LD50 by inhalation to be 225 mg/kg for rats and 355 mg/kg for mice.
The exposure concentration and the calculations to arrive at the LD50
dose were not given in the abstract. Workers have reported that the
dust is irritating to the mucous membrane of the nose and throat.
Irritancy Tests—Rabbit eyes exposed to solid material showed
slight conjunctival and slight iritic congestion. Exposure of rabbit
skin under occlusion caused minimal irritation on intact skin and
slightly more on abraded skin (Dow, 1969).
Commercial samples have produced chloracne in the rabbit ear
bioassay; whereas, the purified material has not. Positive reactions
have been produced by topical or oral application (Johnson et al.,
1973). Allergic contact dermatitis has not been a problem in handling
the chemical.
-------
Mutagenic-Cytotoxic Potential—PCP has not shown mutagenic activity
in the Ames test (Anderson et al., 1972), the host-mediated assay
(Buselmaier et al.t 1973), or the sex-linked lethal test on drosophila
(Vogel and Chandler, 1974).
Teratogenic and Embryotoxic Potential—PCP did not cause
deformities, but it was highly embryolethal and embryotoxic following
oral administration to rats of 15, 30, or 50 mg/kg per day on days 6-15
of gestation. No effects were produced at 5 mg/kg (Schwetz and Gehring,
1973; Schwetz et al., 1974). Purified PCP, with its low nonphenolic
content, was slightly more toxic than the commercial grade (Schwetz et
al., 1974).
Oral administration of PCP to golden Syrian hamsters at levels
ranging from 1.25 to 20 mg/kg daily from days 5 to 10 of gestation
resulted in fetal deaths and/or resorptions in three of six test groups.
PCP was found in the blood and fat of the fetuses (Hinkle, 1973).
Pregnant rats (Charles River-CD Strain) were given 60 mg/kg of
labeled PCP on days 8 through 13 of gestation and were sacrificed on the
20th day. Only a small amount of PCP crossed the placental barrier and
only slight teratogenic effects were noted (Larsen et al., 1975).
One of the concerns in use of technical grade PCP is the presence
of trace contaminants including the chlorinated dioxins and furans.
Limited toxicity data on two of the dioxins present in technical grade
PCP—hexachlorodibenzo-p-dioxin and octachlorodibenzo-p-dioxin--are
given in Table 12.
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52
Table 12. Toxicity of various dioxin isomers to experimental animals.
Compound
LD-50
Teratogenic
Effect**
Embryo
Toxicity*3
Acnegenic
Effectb
mR/k* Body wt.
mg/kR/day
mg/kg/day
rag/liter
2,7-Dichlorodi-
benzo-£-dioxin
1,000
None
None
None
2,3,7.8-Tetrachloro-
dibenzo-£-dioxin
0.0006
0.001
0.00003
0.00004
Hexachlorodibenzo-£-
dioxin
100
0.1
0.0001
0.01
Octachlorodibenzo-£-
dioxin
1,000
None
100
None
a Source: Modified from Alliot, 1975.
^ Values denote the lowest dosage or concentration which gives rise to the
corresponding effect.
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53
Plant/Animal Uptake of Creosote
There is very little information on bioaccumulation/toxicity of
creosote (Brown et al., 1984). The limited information on plant/animal
uptake has recently been reviewed by the USDA (1980). There is
considerably more information on the bioaccumulation/toxicity of the
individual PAH1s found in creosote. Edwards (1983), in a comprehensive
review of PAH's in the terrestrial environment, summarizes the sources
and fate of these compounds in the environment. His conclusions
regarding the uptake, translocation, and metabolism in vegetation were
1) Some terrestrial plants can take up PAH's through their roots
and/or leaves and translocate than to various other plant
parts.
2) Uptake rates are dependent on PAH concentrations, solubility,
phase (vapor or particulate], molecular size, support media
anchoring the plants, and plant species.
3) PAH's may concentrate in certain plant parts more than in other
parts.
4) Some PAH's can be catabolized by plants.
The health effects of the major PAH constituents in creosote are
summarized in Table 13.
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54
Table 13. Health effects of chemical constituents of creosote (U.S. EPA 1984).
Compound
Effect
1. Unsubstituted 6-membered aromatic ring systems
2.
chrysene
pyrene
benzo(a)pyrene
benzo(e)pyrene
benzo(a)anthracene
benzo(a)phenanthrene
naphthalene
phenanthrene
anthracene
dibenzanthracene
acenaphthene.
triphenylene
Unsubstituted aromatic ring
mutagenic initiator, carcinogenic
co-carcinogen [with fluoranthene
benzo(a)pyrene], mutagenic
mutagenic carcinogenic, fetotoxic,
teratogenic
carcinogenic, mutagenic
mutagenic, carcinogenic
initiator, mutagenic
inhibitor
initiator, mutagenic
mutagenic
mutagenic
mutagenic
mutagenic
systems containing 5-numbered rings
fluoranthene
benz(j) fluoranthene
fluorene
co-carcinogenic, .initiator, mutagenic
carcinogenic, mutagenic
mutagenic
-------
55
Table 13. (continued)
Compound
T. Heterocyclic nitrogen bases
TTTecF
N'
quinoline
indole
benzocarbazoles
isoquinoline
1-methyl isoquinoline
isoquinoline
quinoline
quinoline
quinoline
isoquinoline
isoquinoline
isoquinoline
isoquinoline
3-methyl
5-methyl
4-methyl
6-methyl
5-methyl
7-methyl
6-methyl
1,3-dimethyl
acridine
carbazole
carcinogenic
mutagenic
carcinogenic
mutagenic
possibly carcinogenic
possibly carcinogenic
possibly carcinogenic
possibly carcinogenic, mutagenic
possibly carcinogenic
possibly carcinogenic
possibly carcinogenic
possibly carcinogenic
possibly carcinogenic
mutagenic
mutagenic
4. Heterocyclic oxygen and sulfur compounds
coumarone
thionaphthene
No effects found in the literature
for this structural class.
5. Alky1 substituted compounds
1-methyl naphthacene
2-methyl anthracene
methyl fluoranthene
1-methyl naphthalene
2-methyl naphthalene
ethyl naphthalene
2,6-dimethyl naphthalene
1,5-dimethyl naphthalene
2.3-dimethyl naphthalene
2.3.5-trimethyl naphthalene
2.3.6-trimethyl naphthalene
methyl chrysene
1.4-dimethyl phenanthrene
1-methylphenanthrene
mutagenic
mutagenic
possibly carcinogenic
inhibitor
inhibitor
inhibitor
inhibitor
inhibitor
accelerator
inhibitor
accelerator
initiator
initiator, mutagenic
mutagenic
-------
56
Table 13. (continued)
Compound
Effect
6. Hydroxy compounds
phenol
p-cresol
o-cresol
m-cresol
7. Aromatic amines
OH
2-naphthylamine
p-toluidine
o-toluidine
2.4-xylidine
2.5-xylidine
8. Paraffins and naphthenes
promoter
promoter
promoter
promoter
NH:
carcinogenic
carcinogenic
carcinogenic
carcinogenic
carcinogenic
n (n is large, e.g., greater than 15)
No effects found in the literature for this structural class.
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110
REFERENCES
Adams, J. and C. Giam. 1984. Polynuclear Azaarenes in Wood
Preservative Wastewater. Environ. Sci. Techno!. 18(5):391-394.
Ahlborg, V. G., J. E. Lindgren, and M. Mercier. 1974. Metabolism of
Pentachlorophenol. Arch. Toxicol. 32(4):271-281.
Alliot, H. 1975. Chlorodioxins in Pentachlorophenol. British Wood
Pres. Assoc. News Sheet. London.
Allison, L. E. 1935. Organic soil carbon by reduction of chromic
acid. Soil Sci. 40:311-320.
Anderson, K. J., E. G. Leighty, and M. T. Takahashi. 1972. Evaluation
of Herbicides for Possible Mutagenic Properties. J. Agr. Food
Chem. 20:649-656.
Barr, A. J., J. H. Goodnight, and J. P. Sail. 1979. SAS Users Guide.
SAS Institute, Raleigh, NC, 494 pp.
Becker, G. 1977. Experience and Experiments with Creosote for
Crossties. Proc. Am. Wood-Pres. Assoc. 73:16-25.
Bevenue, A. and H. Beckman. 1967. Pentachlorophenol: A Discussion of
Its Properties and Its Occurrence as a Residue in Human and Animal
Tissues. Residue Rev. 19:83-134.
Blake, G. R. 1965. Bulk density: Core method. In C. A. Black (Ed.)
Methods of Soil Analysis, Part I, Agronomy 9:375-377. Amer. Soc.
of Agron., Madison, WI.
Braun, W. H. and M. W. Sauerhoff. 1976. The Pharmacokinetic Profile of
Pentachlorophenol in Monkeys. Toxicol. Appl. Pharmacol.
38:525-533.
Briggs, G. G. 1975. The Behavior of the Nitrification Inhibitor
"N-Serve" in Broadcast and Incorporated Application to Soil. J.
Sci. Food Agric. 26:1083-1092.
Brown, K. W. and Associates. 1980. Hazardous Waste Land Treatment.
SW-874, U. S. Environmental Protection Agency, Washington, DC.
anc' K. C. Donnelly. 1984. Mutagenic Activity of Runoff
and Leachage Water from Hazardous Waste Land Treatment. Environ.
Pollut. (Series A) 35:229-246.
Bulman, T. L., S. Lesage, P. J. A. Fowles, and M. 0. Webber. 1985. The
Persistence of Polynuclear Aromatic Hydrocarbons in Soil. PACE
Report No. 85-2, Petroleum Assoc. for Conservation of the Canadian
Environ. Ottawa, Ontario.
-------
Ill
Burdeil, C. A. 1984. Overview of the Wood Preserving Industry, pp.
7-14. IN: Hazardous Waste Treatment and Disposal in the Wood
Preserving Industry, Atlanta, GA.
Buselmaier, W., G. Roehrborn, and P. Propping. 1973. Comparative
Investigations on the Mutagenicity of Pesticides in Mammalian Test
Systems. Mutat. Research 21(1):25-26.
Buser, H. R. 1975. Polychlorinated Dibenzo-p-dioxins, Separation and
Identification of Isomers by Gas Chromatography - Mass
Spectrometry. J. Chromatog. 114:95-108.
. 1976. High Resolution Gas Chromatography of
Polychlorinated Dibenzo-p-dioxins and Dibenzofurans. Anal. Chem.
48:1553.
Butterfield, 0. J. and J. 0. Devay. 1975. An Improved Soil Assay for
Verticillim dahliae. Proc. Am. Phytopathol. Soc. 2:111 (Abstract).
and J. D. Devay. 1977. Reassessment of Soil Assay for
Verticillim dahliae. Phytopathology 67:1073-1078.
Carrol, 0. 1970. Clay minerals: A guide to their X-ray
Identification. The Geological Society of America. Special paper
126. Boulder, CO. 80 p.
Cerniglia, C. E. and D. T. Gibson. 1979. Oxidation of Benzo(a)-pyrene
by the Filamentous Fungus Cunninghamelia elegans. J. Biol. Chem.
254(23):12174-12180.
and S. A. Crow. 1981. Metabolism of Aromatic Hydrocarbons
by Yeasts. Arch. Microbiol. 129:9-13,
. 1984. Microbial Metabolism of Polycyclic Aromatic
Hydrocarbons, pp. 30-71. IN: A. I. Laskin, Ed. Adv. in Appl.
Microbiol., Vol. 30, Academic Press, New York, NY.
Choi, J. and S. Aomine. 1972. Effects of the Soil on the Activity of
Pentachlorophenol. Soil Sci. Plant Nutr. 18(6):255-260.
. 1974. Adsorption of Pentachlorophenol by Soils. Soil
Sci. Plant Nutr. 20(2).-135-144.
. 1974a. Mechanisms of Pentachlorophenol Adsorption by
Soils. Soil Sci. Plant Nutr. 20(4):371-379.
Chu, J. P. and E. 0. Kirsch. 1972. Metabolism of Pentachlorophenol by
an Axenic Bacterial Culture. Appl. Microbiol. 23(5):1033-1035.
. 1973. Utilization of Halophenols by a Pentachlorophenol
Metabolizing Bacterium. Dev. Ind. Microbiol. 14:264-273.
Crosby, 0. G. 1981. Environmental Chemistry of Pentachlorophenol. Pure
Appl. Chem. 53:1052-1080.
-------
112
Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Biodeterior. Bull. 8(4):135-138.
Day, P. R. 1965. Particle fractionation and particle size analysis.
In C. A. Black (Ed.) Methods of Soil Analysis, Part I. Agronomy
"97552-562. Amer. Soc. of Agron., Madison, WI.
Oeichmann, W. B., W. Machle, K. V. Kitzmiller, and 6. Thomas. 1942.
Acute and Chronic Effects of Pentachlorophenol and Sodium
Pentachlorophenate upon Experimental Animals. J. Pharm. Exptl.
Therap. 76:104.
and L. 0. Schafer. 1942. Spectrophotometry Estimation of
Pentachlorophenol in Tissues and Water. Ind. Eng. Chem., Anal. Ed.
14(4)-.310-312.
Demidenko, N. M. 1966. Toxicological Properties of Pentachlorophenol.
Gig. Toksikol. Pestits. Klin. Otravleni. (4):234-239.
. 1969. Maximum Permissible Atmospheric Concentration of
Pentachlorophenol. Gig. Tr. Prof. Zabol. 13(9):58-60. (CA
72-.47095M).
Dixon, J. B. and S. B. Weed. 1978. Minerals in Soil Environments.
Soil Sci. Soc. of Amer., Madison, WI.
Dodge, R. H. and D. T. Gibson. 1980. Fungal Metabolism of
Benzo(a)anthracene. p. 138. IN: Abstracts of the 1980 American
Society for Microbiologists Annual Meeting. ASM, Washington, DC.
Dow Chemical Co. 1969. Toxicity Summary for Qowicide 7.
Oreisbach, R. H. 1963. Handbook of Poisoning: Diagnosis and
Treatment, p. 256.
Edgehill, R. U. and R. K. Finn. 1982. Isolation, Characterization and
Growth Kinetics of Bacteria Metabolizing Pentachlorophenol. Eur.
J. Appl. Microbiol. Biotechnol. 16:179-184.
Edwards, N. T. 1983. Polycyclic Aromatic Hydrocarbons (PAH's) in the
Terrestrial Environment—a Review. J. Environ. Qual. 12:427-441.
EPRI. 1984. Development and Validation of a Terrestrial Microcosm Test
System for Accessing Ecological Effects of Utility Wastes, Final
Report. EA-XXXX-RP1224-5.
ERT, Inc. 1985b. The Land Treatability of Creosote Wastes (second
draft). Document No. PD481-400a, Environmental Research and
Technology, Concord, MA.
Evans, W. C., H. N. Fernley, and E. Griffiths. 1965. Oxidative
Metabolism of Phenanthrene and Anthracene by Soil Pseudomonads.
Biochem. J. 95:791-831.
-------
113
Feci. Proc. 1943. Fed. Am. Soc. Exp. Biol. 2:76.
Fernley, H. N. and W. C. Evans. 1958. Oxidative Metabolism of
Polycyclic Hydrocarbons by Soil Pseudomonads. Nature 182:373-375.
Gabrilevskaya, L. N. and V. P. Laskina. 1964. Maximum Permissible
Concentrations of PCP and Na-Pentachlorophenolate in Water
Reservoirs. Sanit. Okhrana Vodoemov. ot. Zagryazneniya Prom.
Stochnymi Vodami. (6):251-272. (CA 62;15304d).
Gaines, T. H. 1969. Acute Toxicity of Pesticides. Toxicol. Appl.
Pharmacol. 14(3):515-534.
Gardner, W. S., R. F. Lee, K. R. Tenore, and L. W. Smith. 1979.
Degradation of Selected Polycyclic Aromatic Hydrocarbons in Coastal
Sediments: Importance of Microbes and Polychaete Worms. Water,
Air, Soil Pollution 11, 339.
Gibson, D. T. 1972. The Microbial Oxidation of Aromatic Hydrocarbons.
Crit. Rev. Microbiol. 1(2):199-223.
. V. Mahadevan, D. M. Jerina, H. Yagi, and H. J. C. Yeh.
1975. Oxidation of the Carcinogens Benzo(a)pyrene and
Benzo(a)anthracene to Oihydrodiols by a Bacterium. Science
189:295-297.
Groenewegen, 0. and H. Stolp. 1976. Microbial Breakdown of Polycyclic
Aromatic Hydrocarbons. Tbl. Bakt. Hyg. I. Abt.: Orig. B162,225.
. 1981. Microbial Breakdown of Polycyclic Aromatic
Hydrocarbons, pp. 233-240. IN: M. R. Overcash, ed. Decomposition
of Toxic and Nontoxic Organic Compounds in Soils. Ann Arbor Science
Publishers, Inc., Ann Arbor, MI.
Harrison, D. I. 1959. The Toxicity of Wood Preservatives to Stock,
Part I: Pentachlorophenol. New Zealand Vet. J. 7:89-98. (CA
55:23814e).
Herbes, S. E and L. R. Schwall. 1978. Microbial Transformations of
Polycyclic Aromatic Hydrocarbons in Pristine and
Petroleum-Contaminated Sediments. Appl. Environ. Microbiol. 35,
306.
. G. R. Southworth, D. L. Shaeffer, W. H. Griest, and M. P.
Masbarinec. 1980. Critical Pathways of Polycyclic Aromatic
Hydrocarbons in Aquatic Environments, pp. 113-128. IN: H.
Witschi, ed. The Scientific Bases of Toxicity Assessment,
Elsevier, Holland.
Hetrick, L. A. 1952. The Comparative Toxicity of Some Organic
Insecticides as Termite Soil Poisons. J. Econ. Entomol.
45(2):235-237.
-------
114
Hilton, H. W. and Q. H. Yuen. 1963. Adsorption of Several
Pre-Emergence Herbicides by Hawaiian Sugar Cane Soils. J. Agric.
Food Chem. 11(3):230-234.
, and N. S. Nomura. 1970. Distribution of Residues from
Atrazine, Ametryne, and Pentachlorophenol in Sugarcane. J. Agric.
Food Chem. 18(2)217-220.
Hinkle, D. K. 1973. Fetotoxic Effects of Pentachlorophenol in the
Golden Syrian Hamster. Tox. and Appl. Pharmacol. 25(3):455
(abstract).
Huddleston, R. L., C. A. Bleckmann, and J. R. Wolfe. 1986. Land
Treatment Biological Degradation Processes, pp. 41-61. IN: R. C.
Loehr and J. F. Malina, Jr., eds. Land Treatment:A Hazardous Waste
Management Alternative. Water Resources Symp. No. 13, Center for
Research in Water Resources, Univ. of Texas at Austin, TX.
Ide, A., Y. Niki, F. Sakamoto, I. Watanabe, and H. Watanabe. 1972.
Decomposition of Pentachlorophenol in Paddy Soil. Agric. Biol.
Chem. 36(11):937-1844.
Jackson, M. L. 1956. Soil Chemical Analysis - advanced course. Publ.
by author, Univ. of Wisconsin, Madison.
Jaworski, E. G. 1955. Tracer Studies With 1-^C-Pentachlorophenol in
Cotton. Proc. 10th Annu. Cotton Defol. Conf. pp. 36-40.
Johnson, R. L., P. J. Gehring, R. J. Kociba, and B. A. Schwetz. 1973.
Chlorinated Dibenzodioxins and Pentachlorophenol. Environ. Health
Perspect. 5:171-175.
Karickhoff, S. W., D. S. Brown, and T. A. Scott. 1979. Sorption of
Octanol/Water Distribution Coefficients, Water Solubilities, and
Sediment/Water Partition Coefficients for Hydrophobic Organic
Pollutants. EPA-600/4-79-032. U.S. Environmental Protection
Agency.
Kaufman, D. D. 1978. Degradation of Pentachlorophenol in Soil and by
Soil Microorganisms. IN: Pentachlorophenol, R. K. Rao, Ed. Plenum
Press, New York. pp. 27-40.
Kehoe, R. A., W. Deichmann-Gruebler, and K. V. Kitzmiller. 1939. Toxic
Effects upon Rabbits of Pentachlorophenol and Sodium
Pentachlorophenate. J. Indust. Hyg. & Toxicol. 21:160-172.
Kirsch, E. J. and J. E. Etzel. 1973. Microbial Decomposition of
Pentachlorophenol. J. Water Pollut. Control Fed. 45(2):359-364.
Klute, A. 1965. Laboratory measurement of hydraulic conductivity of
saturated soil, jn C. A. Black (Ed.) Methods of Soil Analysis,
Part I. Agron. 9:214-215. Amer. Soc.- of Agron., Madison, WI.
-------
115
Koss, G. and W. Koransky. 1978. Pentachlorophenol:Chemistry,
Pharmacology, and Environmental Toxicology, K. R. Rao, Ed. Plenum
Press, New York.
Kuwatsuka, S. and M. Igarashi. 1975. Degradation of Penta in Soils:
II. The Relationship Between the Degradation of Penta and the
Properties of Soils, and the Identification of the Degradation
Products of Penta. Soil Sci. Plant Nutr. 21(4):405-414.
Larsen, R. V., L. E. Kirsh, S. M. Shaw, J. G. Christian, and G. S. Born.
1972. Excretion and Tissue Distribution of Uniformly Labeled
14C-Pentachlorophenol in Rats. J. Pharm. Sci. 61:2004-2006.
. G. S. Born, W. V. Kessler, S. M. Shaw, and D. C. Von
Sickle. 1975. Placental Transfer and Teratology of
Pentachlorophenol in Rats. Environ. Lett. 10(2):121-128.
Lorenz, L. R. and L. R. Gjovik. 1972. Analyzing Creosote by Gas
ChromatographyrRelationship to Creosote Specifications. Proc.
Amer. Wood Pres. Assoc. 68:32-42.
Loustalot, A. J. and R. Ferrer. 1950. The Effect of Some Environmental
Factors on the Persistence of Sodium Pentachlorophenate in the
Soil. Proc. Am. Assoc. Hortic. Sci. 56:294-298.
Matsunaka, S. and S. Kuwatsuka. 1975. Environmental Problems Related
to Herbicidal Use in Japan. Environ. Qual. Safety. 4:149-159.
Means, J. C., G. S. Wood, J. J. Hassett, and W. L. Banwart. 1979.
Sorption of Polynuclear Aromatic Hydrocarbons by Sediments and
Soils. Environ. Sci. Techno!. 14:1524-1528.
Medvedev, V. A. and V. 0. Davidov. 1972. Transformation of Individual
Organic Products of the Coke Industry in Chernozem Soil.
Pochrovedenie. 11:22-28.
Miller, C. S. and M. M. Aboul-Ela. 1969. Fate of Pentachlorophenol in
Cotton. J. Agric. Food Chem. 17(6):1244-1246.
Mississippi State University. 1984. Methylene Chloride Soxhlet
Recoveries for 0CDD and PCP in Soil. Report for MFPUL
Environmental Group, Mississippi State, MS.
McKenna, E. J. and R. 0. Heath. 1976. Biodegradation of Polynuclear
Aromatic Hydrocarbon Pollutants by Soil and Water Microorganisms.
Water Resources Center, University of Illinois at Urbana-Champaign.
Research Report No. 113, UILU-WRC-76-0113.
Murthy, N. B. K., D. 0. Kaufman, and G. F. Fries. 1979. Degradation of
Pentachlorophenol in Aerobic and Anaerobic Soil. J. of Environ.
Sci. Health, B14:1-14.
-------
116
Noakes, D. N. and D. M. Sanderson. 1969. A Method for Determining the
Dermal Toxicity of Pesticides. British J. of Indust. Med.
26:59-64.
Ochrymowych, J., Western Electric. 1978. Personal communication.
Overcash, M. R. and D. Pal. 1979. Design of Land Treatment Systems for
Industrial Wastes - Theory and Practice. Ann Arbor Science
Publishers, Inc., Ann Arbor, MI. 684 pp.
, J. B. Weber, and M. C. Miles. 1982. Behavior of Organic
Priority Pollutants in the Terrestrial System: Di(N-Butyl)
Phthalate Ester, Toluene, and 2,4-Dinitrophenol. Office of Water
Research and Technology. U. S. Department of the Interior,
Washington, DC.
Peech, M. 1965. Exchange acidity. Jn_ C. A. Black (Ed.) Methods of
Soil Analysis, Part I, Agronomy 9:914-926. Amer. Soc. of Agron.,
Madison, WI.
Phung, T., L. Barker, D. Ross, and D. Bauer. 1978. Land Cultivation of
Industrial Wastes and Municipal Solid Wastes: State-Of-The-Art
Study. Volume 1, Technical Summary and Literature Review.
EPA-600/2-78-140a, U. S. Environmental Protection Agency,
Washington, DC.
Pleskova, A. and K. Bencze. 1959. Toxic Properties of
Pentachlorophenol. Pracovni Lekerstvi, 11:348-354.
Reichhold Chemicals. 1974. Report of May 28, 1974.
Renberg, L. 1974. Ion Exchange Technique for the Determination of
Chlorinated Phenols and Phenoxy Acids in Organic Tissue, Soil, and
Water. Anal. Chem. 46(3):459-461.
Richards, L. A. 1949. Methods of Measuring Soil Moisture. Soil Sci.
68:95-112.
Rogoff, M. H. 1961. Oxidation of Aromatic Compounds by Bacteria. Adv.
Appl. Microbial. 3:193-221.
Schwetz, B. A. and P. J. Gehring. 1973. The Effect of
Tetrachlorophenol and Pentachlorophenol on Rat Embryonal and Fetal
Development. Toxicol. Appl. Pharmacol. 25(3):455. (Abstract).
, P. A. Keeler, and P. J. Gehring. 1974. The Effect of
Purified and Commercial Grade Pentachlorophenol on Rat Embryonal
and Fetal Development. Toxicol. Appl. Pharmacol. 28(1):151-161.
Shabad, L. M., Y. L. Cohan, A. P. Ilnitsky, A. Y. Khesina, N. P.
Shcerbak, and G. A. Smirnov. 1971. The Carcinogenic Hydrocarbon
Benzo(a)pyrene in the Soil. J. Natl. Cancer Inst.
47(6):1179—1191.
-------
117
Sims, R. C. 1982. Land Treatment of Polynuclear Aromatic Compounds.
Ph.D. Dissertation. Dept. Biol. Agr. Eng., North Carolina State
Univ., Raleigh, NC.
, and M. R. Overcash. 1983. Fate of Polynuclear Aromatic
Compounds (PNAs) in Soil-Plant Systems. Residue Rev. 88:1-68.
, J. L. Sims, D. L. Sorensen, and L. L. Hastings. 1987.
Waste/Soil Treatability Studies for Four Complex Industrial Wastes:
Methodologies and Results. Vol. 1. Project # CR-810979.
Sisler, F. D. and C. E. Zobell. 1947. Microbial Utilization of
Carcinogenic Hydrocarbons. Science 106:521-522.
Soil Survey Staff. 1951. Soil Survey Manual. Agric. Handb. No. 18,
USOA. U. S. Govt. Printing Office, Washington, D.C.
Sudhakar-Barik and N. Sethunathan. 1978. Metabolism of Nitrophenols in
Flooded Soils. J. Environ. Qual. 7:349-352.
Suzuki, T. and K. Nose. 1971. Decomposition of Pentachlorophenol in
Farm Soil. (Part 2). Penta Metabolism by a Microorganism Isolated
from Soil. Noyaku Seisan Gijutsu, Japan, 26:21-24.
Tausson, V. 0. 1950. Basic Principles of Plant Bioenergetics
(collected works), p. 73. j[n: N. A. Maximov, (Ed.), National
Academy of Sciences, USSR.
Tortensson, L. and J. Stenstrom. 1986. "Basic" Respiration Rate as a
Tool for Prediction of Pesticide Persistence in Soil. Toxicity
Assessment 1:57-72.
United States Department of Agriculture. 1972. Soil Survey Laboratory
Methods and Procedures for Collecting Soil Samples. Soil Survey
Investigations Report No. 1. U. S. Govt. Printing Office,
Washington, DC.
. 1980. The Biologic and Economic Assessment of
Pentachlorophenol Inorganic Arsenicals Creosote. USDA, Number
1658-11. Washington, DC.
U.S. EPA. 1975. Production, Distribution, Use, and Environmental
Impact Potential of Selected Pesticides. U. S. Environ. Prot.
Agency 540/1-74-001. 439 pp.
. 1978. Report of the Ad Hoc Study Group on
Pentachlorophenol Contaminant. Environmental Health Advisory
Committee. Science Advisory Board, Washington, DC.
1983. 40CFR Parts 261, 264, 265, and 775. Federal
Register. 48(65).
. 1984. Creosote - Special Review Position Document 213.
U. S. Environmental Protection Agency, Washington, DC.
-------
118
1986a. Test Methods for Evaluating Solid Waste. IB.
SW-846. Third Edition.
1986b. Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations. Final Draft. EPA-530/SW86-032. Office
of Solid Waste and Emergency Response, U.S. Environmental
Protection Agency, Washington, DC.
Versar, Inc. 1979. Water-Related Environmental Fate of 129 Priority
Pollutants, Vol. 1 and 2, EPA 440/4-79-029. U.S. Environmental
Protection Agency, Washington, DC.
Verschueren, D. 1977. Handbook of Environmental Data on Organic
Chemicals. Van Nostrand/Reinhold Co., New York. p. 659.
Vogel, E. and J. L. R. Chandler. 1974. Mutagenicity Testing of
Cyclamate and Some Pesticides in Drosophila melanogaster.
Experientia 30(6) .*621-623.
Warcup, J. H. 1950. The Soil Plate Method for Isolation of Fungi from
Soil. Nature 166:117-118.
Ward, C. H., M. B. Thomson, P. B. Bedient, and M. D. Lee. 1986.
Transport and Fate Processes in the Subsurface, pp. 19-39. IN: R.
C. Loehr and J. F. Malina, Jr., Eds. Land Treatments Hazardous
Waste Management Alternative. Water Resources Symp. No. 13, Center
for Research in Water Resources, Univ. of Texas at Austin, TX.
Watanabe, I. 1973. Isolation of Pentachlorophenol Decomposing Bacteria
from Soil. Soil Sci. Plant Nutr. Tokyo. 19(2):109-116.
Williams, R. T. 1959. Detoxification Mechanisms. 2nd Ed., John Wiley
and Sons, Inc., New York, NY. 796 pp.
Young, H. C. and J. C. Carroll. 1951'. The Decomposition of
Pentachlorophenol When Applied as a Residual Pre-Emergence
Herbicide. Agron. J. 43:504-507.
Yuan, T. L. 1959. Determination of Exchangeable Hydrogen in Soils by a
Titration Method. Soil Sci. 88:164-167.
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APPENDIX B
SUPPLEMENTARY MATERIAL FOR
FIELD EXPERIENCE WITH THE KPEG REAGENT
Alfred Kornel, EPA-RREL, Cincinnati, OH
-------
CHEMICAL OESTRUCTION/OETOXIFICATION OF CHLORINATED OIOXINS IN SOILS
Robert L. Peterson
Edwlna Mlllclc
Gal son Research Corporation
East Syracuse, New York 13057
Charles J. Rogers,
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
ABSTRACT
Laboratory experiments using 1,2,3,4 tetrachlorod1benzo-p-d1ox1n show that
chlorinated dloxlns 1n soil may be chemically reduced to levels below one part per
billion. The decontamination processes Involve the addition to the soil of a mixture
of alkali metal hydroxide, polyethylene glycols or capped polyethylene glycols,
dimethyl sulfoxide and water. The reagent 1s either added directly to the soil with
mixing (1n-s1tu process) or mixed 1:1 by volume with soil In an external reactor
(slurry process). The dloxln Is dechlorlnated to a water soluble form, which may be
then removed from the soil (slurry process) or allowed to blodegrade (1n-situ process).
INTRODUCTION
The contamination of large areas of
soil with dloxln have created a need for a
cleanup method which Is capable of
handling large volumes of contaminated
soil 1n a cost effective manner. Propos-
ed treatment methods Include Incinera-
tion, solvent extraction and direct
chemical dechlorination. This paper will
discuss the successful use of direct
chemical dechlorination In decontamina-
tion of dloxln contaminated soils on a
laboratory scale and the implications of
these data for large scale soil treatment.
The basis for use of chemical
dechlorination as a decontamination
method lies 1n the relationship between
the toxicity of chlorinated dloxlns and
the number of chlorine atoms on the
dloxln molecule. In order for a dloxln
Isomer to exhibit high toxicity a mini-
mum of three chlorine atoms are requir-
ed, and these must be In the 2,3, and 7
positions (1). In addition, the lipophilic
nature of many chlorinated dloxlns
contributes to their bloaccumulatlon
activity. The dechlorination processes
used 1n this study reduce the number of
chlorine atoms on the dloxln molecule
and produce a hydrophlUc material which
1s more easily removed from the soil
than the parent dloxln.
PURPOSE
The purpose of this project 1s to
Identify and evaluate at the laboratory
level an effective chemical process for
destruction/detoxification of chlorin-
ated dioxins 1n soil.
APPROACH
Qlrect chemical decontamination o*
soil can be considered to be a two step
process;
1. Application of the reagent to the
dloxln contaminated soil
2. Reaction of the dloxln and reagent
These two aspects of the process
Interact. For example, a reagent with
high mobility 1n soil requires a less
rigorous application method than a
reagent which 1s highly viscous.
-------
However at a minimum the reagent must
be capable of reducing dloxin
concentrations to <1 ppb. or favorable
mobility and ease of application become
irrelevant. For this reason, the reaction
system was selected first, with the
method of application designed around
the reagent system.
Application methods for direct
decontamination of soil must be
compatible with the reaction system
selected. In order for a direct chemical
reaction process to be effective, the
contaminated soil and reagent must be
brought into close contact. The degree
of contact between soil and reagent may
be increased by mechanical mixing, by
addition of diluents and co-solvents to
increase the neagent mobility, and by
heating the soil/reagent mixture to
reduce the viscosity of the reagent.
After selection of the reaction system, a
variety of application methods were
tested under laboratory conditions for
use 1n dloxin soil decontamination.
In order to reduce the costs of
handling and analyzing soil samples, a
low toxicity dloxin isomer, 1,2,3,4
tetrachloro-p-dibenzo dioxin {TCDO), was
used in place of 2,3,7,8 TCDD for all
testing. Laboratory tests of 2,3,7,8
TCDO and 1,2,3,4 TCDO Indicated that
rates of reaction for the two isomers
were sufficiently similar to allow
generalization of results between
isomers.
To Insure sample uniformity, all
samples for treatment used uncontamin-
ated soil which was spiked with a known
amount of dioxin. Each soil sample was
spiked individually, with the entire
sample used for analysis. Uncontam-
inated soil samples were obtained from
the vicinity of a dloxin site 1n
Mississippi and spiked with 1,2,3,4 TCDD
before processing. Soil from an authen-
tic test site was used to avoid the wide
variations seen 1n previous tests of
treatability of different PCB contam-
inated soils. It was anticipated that
dloxin contaminated soils would show
similar variations.
PROBLEMS ENCOUNTERED
Major problems encountered during
this project involved the analytical
procedure. Analysis of soil samples by
gas chromatography was frustrated by
the large number of interferences found
1n the test site soils. The Interference
problem was exacerbated by the ability
of the reagents used to extract materials
from the soil which were not extracted
by the analytical solvents used. While
this high extraction efficiency for the
treatment solvents contributed to the
success of the dloxin destruction, it
complicated the analysis. The failure of
cleanup procedures to produce an
acceptable sample necessitated a move
to gas chromatography/mass
spectroscopy as the primary method of
analysis.
An additional problem was caused by
the tendency of the test site soil to
solidify 1f exposed to high temperatures
(lOCrC or above) under alkaline condi-
tions. This problem was solved by
moving to lower temperatures, which
proved adequate for purposes of
treatment.
RESULTS AND QISCUSSfQN
Selection of Reagent System - Of the
available reactions,-including ultraviolet
dechlorination, ruthenium tetroxide
oxidation and nucleophilic substitution,
nucleophHlc substitution using alkali
metal hydroxides has given the best
results In both literature studies and
laboratory trials. The preferred
reactions of this type for use with
halogenated aromatics involve combination
of potassium hydroxide and polyethylene
glycols to form an alkoxide, which is
the reactive species. The addltiqn
of a sulfoxide catalyst/co-solvent,
usually dimethyl sulfoxide, greatly
enhances the rate and degree of
reaction, although it 1s not known if
this Is due to the effectiveness of the
sulfoxide as an extractant for
aromatics or to the catalytic effect
of the sulfoxide for substitution
reactions. The probable mechanism for
this class of reactions follows;
ROH + KQH ROK + HOH
Sulfoxide
ArCln + ROK ArCln-10R + KCL
-------
The partially dechlorinated, water soluble
reaction product may continue to undergo
dechlorination, depending on the reaction
conditions. Several reactions of this
type have demonstrated reduction of
dioxin concentrations in liquids to <1 ppb.
Selection of Application Method - A wide
variety of hydroxide/alcohoi/sulfoxide
reaction systems will effectively
dechlorlnate dioxins In liquid solution.
However, application of the reagent to
the soil in such a manner as to allow
these reactions to occur is a significant
problem. The necessary degree of
contact has been achieved using two
different approaches; direct addition of
reagent or a reagent/water mixture to
the soil with mixing 1n place (1n-s1tu
process) and excavation of the soil
followed by mixing equal volumes of soil
and reagent in an external reactor (slurry
process).
Both the slurry and 1n-s1tu process-
es may be used at elevated temperatures.
Heating methods for an 1n-s1tu system
would use radio frequency (RF) or
microwave heating(2). The simplest
method of heating for the slurry process
is to preheat the reagent prior to mixing
of the soil and reagent. 8oth of these
heating methods are applicable to large
scale processing.
The two application methods have
different areas of application. The
in-situ process is limited to areas of
shallow contamination and the soil and
reagent may be mixed with conventional
agricultural- equipment. In addition, the
degree of contamination must be
relatively uniform. If small areas of
high concentration or "hot spots", are
present, the high local concentration of
contaminant might exhaust the amount of
reagent which may be economically
applied. While the concentrations of
dioxin generally observed In the field are
not high enough to cause a problem,
dioxins are often found in combination
with other chlorinated wastes, which
may be present 1n high concentrations.
However, in suitable cases, large areas
of shallow soil contamination could be
treated 1n a fairly short period of time
using the 1n-s1tu procsss. In cases
where dioxin has penetrated to depths >
1-2 feet, or where significant areas of
high concentrations occur, the slurry
process 1s more suitable. The slurry
process, which uses large volumes of
reagent followed by reagent recovery, is
more suited to treatment of "hot spots"
than 1s the 1n-situ process.
Results of Combined Application/
Reaction Process - The slurry and 1n-s1tu
process results will be discussed
separately.
Results of In-sltu Processing - Two
different reagents have been used for
1n-s1tu processing 1n this study;
potassium hydroxide/polyethylene glycol
400/ dimethyl sulfoxide (KOH/PEG/OMSO)
and potassium hydrox1de/2-(2-methoxy
ethoxy ethanol)/dimethyl sulfoxide
(KOH/MEE/DHSO). Water has been added
in some cases as a co-solvent In an
attempt to give readier penetration of
small amounts of reagent into the soil.
Each set of samples had an associated
set of spikes and blanks. The spikes used
reagent without the addition of KOH and
were handled 1n the same manner as the
samples. The blanks were untreated
soil. Samples treated at above ambient
temperatures were maintained uncbver«d
in a water bath unless otherwise noted.
The results of the in-sltu processing are
summarized 1n table 1.
Discussion of In-s1tu Processing
Soike Recovery - The recovery of TCDO
from soikes in the in-situ process was
extremely variable, ranging from 120% to
<4%. In general, the higher the
temperature and longer the hold time, the
lower the spike recovery. Sealing the to?
of the spike reduced the loss of TCDO for
the 2 day KOH/MEE/OMSO run to less
than that for the I day run, indicating
that the lower spike recoveries are
probably due to losses from
volatilization and/or extraction into the
spike solvent (PEG/DMSO or MEE/OMSO),
which is not analyzed. In the slurry
tests, where volatilization is not a
factor, analysis of the spike reagent
showed that some 77% of the original
TCDO was present 1n the spike reagent.
The highest spike recovery was from the
20 C run, which is consistent with the
volatilization hypothesis. Extraction or
the TCDO into a polar solvent would tend
-------
Table I - Summary of Results of In-s1tu Processing - A11 soils Initially at 2000 ppb
wt*
temp.
time.
avg ppb
TCOO
In soil
°C
days
spl
spike
1:1:1 K0H/PEG/0MS0
20
20
7
980
2500
1:1:1 K0H/PEG/0MS0
20
70
7
<1
740
1:1:1 K0H/PEG/0MS0
20
70
1
5.3
730
2:2:2:1 KOH/MEE/OMSO/WATER
20
70
I
3.3
5Q0
2:2:2:1 KOH/MEE/OMSO/WATER
20
70
2
2.8
m*
2:2:2:1 KOH/MEE/OMSO/WATER
20
70
4
2.1
210
2:2:2:1 KOH/MEE/OMSO/WATER
20
70
7
1.2
190
2:2:2:6 KQH/MEE/DMSO/WATER
20
70
7
2.1
140
2:2:2:30 KQH/MEE/QMSQ/WATER
50
70
7
18
170
2:2:2:30 KOH/MEE/OMSO/WATER
20
70
7
50
70
BLANKS - ALL
<1
* SPIKES SEALED
to enhance volatilization, similar to the
effects of water on the volatilization of
PCBs 1n soil (3). It Is Interesting to
note that the worst spike recoveries were
in the MEE reagents which used water as a
co-solvent.
Effects of Temperature - Only two reaction
temperatures have been tested to date using
the in-situ process. The improvemenj 1n
reaction efficiency in going from 20 C to
70 C was dramatic, improving reaction ef-
ficiency from 505 to > 90S.
Effects of Reagent Formulation - PEG vs.
MEE - The test results for tne 70 C reac-
tions were slightly better at 1 day for the
MEE reagent and slightly better at 7 days
for the PEG reagent. This difference does
not appear to be significant.
Effects of Water as a Co-Solvent - Four^
sets of tests were run for 7 days at 70 C
using KOH/MEE/OMSO with water as a CO-
solvent. These data show a good correla-
tion between wt* reagent and TCDD concen-
tration after 7 days, as shown in figure I.
The plot of 5 active reagent vs. ppb TCOO
shows the expected first order relationship.
This demonstrates that dilution of the rea-
gent with water to provide more contact,
followed by evaporation of the water to en-
courage reaction, was not effective in
reducing the amount of reagent required.
The plot of X reagent vs. ppb TCDD
shows the expected first order relation-
ship. This demonstrates that dilution
of the reagent with water to provide more
contact, followed by evaporation of the
water to encourage reaction, was not
effective 1n reducing the amount of
reagent required.
Results of Slurry Processing - The slurry
process conditions tested and the results
of GC/MS analysis are sunmarized in table
2.
As little as 2 hours at 70°C were ade-
quate to reduce TCDD levels from 2000 ppb
to < l ppb, for a removal efficiency of
> 99.95X. The bulk of this removal
occurred In the first 30 minutes, when
< 99X of the TCOO had been reacted. The
reaction at 25 C was slower, but did remove
98* of the original dioxin after two hours.
Reagent Recovery Efficiency - Reagent re-
covery of the PEG reagents by distillation
was only partially successful (about 505
recovery},, due to the poor heat stability
and low vapor pressure of the PEG. Rea-
gent recovery by washing has been more
successful, with 94-99+x recovery of rea-
gent. The degree of recovery is Important
-------
100
PPB
TCOO
10
Figure 1 - wt* active reagent vs
8 10 12
REAGENT
ppb TCDO after 7 days
Table 2 - Results of Slurry Processing
Reagent
Temp, °C
Rxn time, hrs
ppb TCDO
1:1:1 KOH/PEG/DMSO
180-260
4
< 1
1:1:1 KOH/PEG/DMSO
180
2
< 1
1:1:1 KOH/MEE/DMSO
150
2
< 1
1:1:1 KOH/MEE/DKSO
70
2
« 1
1:1:1 KOH/MEE/DMSO
70
0.5
15
1:1:1 KOH/MEE/OMSO
25
2
36
Blanks - all <1 ppb TCDO
Spikes - S recovery in soil - 0.1-5.9
- % recovery 1n decanted solvent - 77
to the overall economics of the process.
PioxIn Recovery Efficiency - Analysis of
the PEG/GMSd) reagent used 1n the slurry
process spikes gave a high recovery of
dioxln (77"). As in the case of the In-
situ samples, slurry spikes were treated
with an alcohol/sulfoxlde mixture without
the addition of alkali. Additional
analysis of both the solvents and the soil
(soil extracted with acetone/hexane after
decantatlon of the alcohol/sulfoxlde) from
the slurry spikes showed the presence of a
large variety of halogenated materials
which were not originally added to the soil
or removed from the soil using the analyti-
cal reagents. The amount of additional
chlorinated material removed from the
untreated soil by the PEQ/DMSO was on the
order of 140 ppm, calculated as lindane.
These materials may be pesticide residues
or naturally occurring chlorinated species-
Analysis of treated slurry samples also
shows these materials, although at much
lower levels. Indicating that these are
some form of aromatic hallde. Results
of analyses for DOT, ODE and chlorinated
dloxin were negative.
These data Indicate that conven-
tional methods or extraction may under-
estimate concentrations of halogenated
-------
organics 1n soil due to an Inability to
remove halogenated species from the humics
present 1n the soil, while reagents
containing PEG/OMSO are capable of remov-
ing these halogenated organlces from
treated soil.
PRELIMINARY ECONOMIC EVALUATION
In order to provide a rough estimate
of relative costs, two scenarios were
constructed. In the first case, a 1 acre
site 3 feet deep was to be treated using
the 1n-s1tu process with radio frequency
heating. Capital costs for this option
are estimated at $2,970,000 for a capacity
of 27,600 tons/year of soil (4). In the
second case, soil was to be excavated and
placed In a 3 reactor slurry process system.
Capital costs for this option are
$2,350,000 for a 40,000 ton/year capacity.
Capital recovery costs for both processes
assumed an interest rate of 145 over 5
years. Cost estimates for the two cases
are shown in table 3. .
Table 3 - Preliminary Economic Analysis of
In-sltu and Slurry Processes
Cost, $/ton soil
Cost Item
1n-s1tu
slurry
Capital recovery
31
17
setup and operatin
65
54
reagent
200
20
Total costs
296
91
The major difference 1n costs between the
two processes 1s in the cost of reagent.
In the 1n-s1tu process, where reagent is
not recovered, this cost Is 67X of the
total cost. For the slurry process, the
operating costs assume a site that Is
reasonably easy to excavate. For cases
where excavation 1s required to levels
below the water table or 1n very rocky
son, this cost could increase greatly,
although this would also be the case for
landfill or incineration. In cases where
excavation 1s difficult, the overall costs
for the in-sltu process may be lower than
for the slurry process.
CONCLUSIONS
1. D1ox1n concentrations 1n soil can
be reduced from 2000 ppb to <1 ppb by
mixing the soil with a combination of
alkali metal hydroxide, alcohol and
sulfoxide.
2. Mixing of the soil and reagent
can be done effectively 1n two different
ways; direct addition of reagent to in-
place soil with one time mixing (1n-s1tu
process) or combination of soil and
reagent in a reaction vessel with
continuous mixing (slurry process).
3. Estimated costs, for processing
are 1n the range of 5100-$300/ton so11.
ACKNOWLEDGEMENTS
This work was supported by the
United States Environmental Protection
Agency under the direction of Mr. C.
Rogers and the United States Air Force
Headquarters Engineering and Service
Center with the assistance of Lt. E. Heyse
under EPA contract 68-03-3219.
REFERENCES
1. Esposlto et al, "01ox1ns" EPA-600/
2-80-197, p 187
2. Oev et al, "Decontamination of
Hazardous Waste Substances from Spills
and Uncontrolled Waste Sites by Radio
Frequency ln-s1tu Heating", 1984
Hazardous Material Spills Conference
3. Mackay and Wolkoff "Rate of
Evaporation of Low Solubility
Contaminants from Water Bodies to
Atmosphere" Environ. Sci. Tech. 7 (7),
611-614
4. Dev, H,, personal cotnnunication
4/3/85
-------
"PREPRINT EXTENDED ABSTRACT"
Presented Before the Division of Environmental Chemistry
American Chemical Society
New Orleans, Louisiana August 30-September 4, 1987
FIELD VALIDATIOM OF THE KPEG PROCESS TO 0CSTROY
PCBs. PCOOs. NAD PCOFs IN contaminated waste
Charles J. Rogers
Hazardous Haste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
The presence of highly tonic and persistent chemicals In liquids, soils,
sediments, and sludges In abandoned waste sites pose a threat to both public
health and the environment. Incineration Is frequently used to destroy high
hazards, however, when operated under less than optimum combustion conditions
acutely hazardous products including PCOOs and PCOFs can be formed and emitted
in the combustion products. Various biological, chemical, and physical methods
have been tested and have been demonstrated to be effective 1n varying degrpes
to destory halo-organlcs of environmental importance.
The U. S. Environmental Protection Agency (EPA) has supported research
Intramurally and extramurally since 1980, to develop an alternative method for
in-situ or on-site destruction of halogenated pollutants. Chemical reagents
prepared from polyethylene glycols and potassium hydroxide (KPEGs) have been
demonstrated under mild conditions (25<,-140°C) to dehalogenate PCBs, PCODs,
and PCDFs to less than 1 ppb. The reaction mechanism is nucleophilic substitu-
tion at an aromatic carbon.
Bench scale studies have already established" condltions for PCB destruc-
tion to less than 1 ppm and PCODs and PCOFs to less than 1 pph. Toxicological
-------
rests h?ve established that arylpolyglycol by-products from KPEG reactions
are nc-'.onic. The non-toxic property of the by-products may allow for delist-
ing anc on-site desposal of treated materials. In July and August 1986, a 2?00
ea)Ion KPEG was used In Butte. Montana on a wood preserving site and in Kent.
Washington on a waste disposal site to successfully destroy PCDDs and PCDFs
(120 ppb - 200 ppm) In 17000 gallons of liquid waste to non-detectable levels,
ft prototype reactor designed to treat both liquids and solids will lie tested in
1987 o" selected Superfund and Department of Defense sites. These field studies
will validate or establish conditions in the prototype reactor for destruction
PCtii ^CDDs and PCDFs to acceptable levels required by the regulations.
This presentation will review treatment data, regulations for treated materials,
costs, and the potentials of KPEG process for the destruction of a variety of
halogenated pollutants.
-PREPRINT EXTENDED ABSTRACT*
Presented before the Division if Environmental Chemistry
American Chemical Society
New Orleans, August 30 - September 4, 1987
DECONTAMINATION OF A SMALL PCB SOIL SITE
8Y THE GALSON APEG PROCESS
C.F. Novosad, E. Milicic. R.L. Peterson
Galson Research Corp.
660! KirKville Rd.
E. Syracuse, N.Y. 13057
and C. Rogers
Office of Research and Development
U.S. EPA
26 W. St. Claire St.
Cincinnati, Ohio 45220
SITE BACKGROUND
Bengart & Memel, Inc. a wholesaler of non-ferrous scrap metals, was originally
founded in 1950 in Buffalo. New York. From the early 1950's through 1978 Bengart &
Memel received and dismantled PCB (polychlorinated biphenyl) transformers and
capacitors, inadvertently releasing PCB into the soil. In the mid-1970s, soil samples
from the property were found to contain greater than 50 ppm of PCBs. The New York
Slate Department of Environmental Conservation subsequently issued a Consent
Order lor remediation which required that the PCB concentration in the soil be reduced
to below SO parts per million.
INTRODUCTION
Galson Research, with the assistance of the US EPA, has developed a patented
chemical process (Galson Terraclene-APEG) which dechlorinates PCBs and dioxins in
soils and sludges. The technology has been proven successful under a variety of
situations in laboratory and field studies. The successful APEG cleanup implemented
at the Bengart & Memel site was a small scale version of the Terradene process,
utilizing 55 gallon drums as the reaction vessels.
«35
-------
The Tsrraclene-APEG process entails the addition ol liquid reagents to
contaminated soil and heating the mixture until the PCBs in the soif decompose to
lower toxicity, water soluble materials. The reactions in this process are shown below.
DMSO
ROH + KOH ~ ROK + HOH (1)
+R0K „ * KCL <2>
The reagent components used in the cleanup operation were dimethyl sulfoxide
(DMSO), polyethylene glycol with an average molecular weight of 400 amu (PEG),
Methylene glycol methyl ether and higher homologs (TMH), 45% aqueous potassium
ivdroxidft (KOH) and water. The reagent formulation used was 2:2:4:7:5
?£G:TMH:DMSO:45% KOH .water. The excess water was added so that the reagent
would be a single liquid phase rather than a 2 phase mixture.
Soil decontamination using the Terradene-APEG process involves 5 basic steps;
1. Sel up the vapor system & enclosure as applicable to the site.
2. Mix reagent and add to reaction drums.
3. Attach heaters, insulation, and vent lines to the reaction drums.
~. Allow drum contents to heat and react.
5. Obtain sample for analysis.
~. Neutralize (and deodorize if desired) the caustic soil.
Fitly-on? drums of PCB contaminated soil were processed utilizing the drums as j
reaction vessels. The single phase liquid reagent was added to the soil drums until the
soil surface ' as covered; the reagent amounted to -20% of the weight of the soil. The
cos; of the r< jgent per drum was about $60.00 without recycle or reuse. Electric drum
heaters (15CV. W) were attached and the drums were heated to at least 100°C lor 2-3
days without fixing and were allowed to cool tor at least 12 hours before sampling.
The dri ;ns were sampled using a 30 Inch soil auger attached to a hand drill.
Four cores v» • e taken Irom each drum, one in the center, one close to the edge and
two spaced between the center and edge in dillerent parts of the drum. Soil was
416
collected by digging as deep as possible with the auger and attempting to bring soil up
from the bottom of the hole. In digging out a core, it was necessary to work around the
large rocks in the drum. Rocks and metal pieces larger than 2 inches in diameter were
not included. The soil from the cores was collected in a plastic bucket and mixed well
with a trowel. Samples were collected from the bucket in wide mouth jars.
Samples were bottle extracted with methanol and hexane. Extracts were
cleaned up by brief washing with concentrated sulfuric acid and analyzed by GC with
electron capture detector. Each peak in the PCB chromatograms was treated as a
separate compound and quantified individually so that an accurate estimate of PCB
concentration could be obtained in spite of the disruption of the aroclor pattern. The
PCB concentration in all 51 of the drums was reduced to below 50 ppm, the required
"clean" level. Selected data are presented in Table 1.
Table 1. Selected Results
description ppm PCB before ppm PCB after
highest initial conc. 195 26.9
second highest initial conc. 167 15.8
highest final conc. by GRC 110 32.7
lowest final conc. 102 7.3
second lowest final conc. 64 7.7
Final PCB concentrations were not correlated with initial concentrations or with
/ 6 variation $£ "| @ $feuser Edwina;docu
to the extreme inhomogeneity of the matrix and differences in permeability of the soil lo
the reagent.
The treated soil was extremely alkaline and had to be brought to a neutral pH
(between 5 and 9) before re-introducing the soil into the environment. Mixing was
required for the neutralization procedure because 'hot spots' of either concentrated
acid or base were unacceptable. The treated soil was shoveled into drums containing
dilute hydrochloric acid and stirred. The pH of the liquid was checked periodically and
more acid or soil was added depending on the pH. The excess liquid was decanted
Irom the soil as a required for disposal. (Although the NYSDEC approved the return of
the neutralized soil to the site, the site owner decided to dispose of the soil in a local
sanitary landfill.)
Sites with small amounts of contaminated soil could use this drum scale process
as an alternative to incineration or landfill. For larger sites this process would become
too labor intensive to compete economically with a multi-Ion per batch slurry unit.
-------
"PREPRINT EXTENDED ABSTRACT'
Presented Before the Division of Environmental Chemistry
American Cheaical Society
Ne* Orleans, Louisiana Auaust 30-Septembet 4. 1981
LABORATORY STUDIES OF THE DEGRADATION OF TOXIC CHLORINATED COMPOUNDS CONTAINED
IN HAZARDOUS CHEMICAL HASTE MIXTURES ANP CONTAHINATED SOILS
USING A POTASSIUM HYDROXIDE/POLYETHYLENE GYLCOl REAGENT
T. O. Tiernan. D. J. Vagel. J. H. Garrett. G. K. VanNeSs.
J. G. Solch. and N. L. Taylor
Departmenr of Chemistry. Wright Stat* University. Dayton. Ohio ISiJS
Polyethylene glycol (PEG1 apparently serves as a phase-transfer catalyst in
the KOH-PEG dehalogenation reaction with halocarbons. The important feature which
the polyethylene glycol-aediated dehalogenat ion reaction offers is that of a
ror.trolled process which occurs at relatively low temperatures. 70"-100«C. In
ror.trast. iiore conventional dehalogenat ion processes using only solid ciustic
jsuii'.y require substantially higher temperatures. and are often violent ot e.iti
inco'ntrol 1 able processes. The rather remarkable catalytic effect o! PEG in su-:h
lehalogenation reactions was initially observed by Kimura and Regen IJ. Org. Che*.
47. 2493 U982), J. Org. Che». 48, 195 (1983)1. although phase-transfer catalysts
have been known for some time IC. H. Starks et. al.. "Phase Transfer Catalysis."
Academic Press, N.Y.. 1918). The studies of Kiaura and Regen suggest that
polymeric alkoxides and/or hydroxides are foraed froa the reaction of KOH or NaOH
with the PEG. Experiaents by these investigators, in which the efficacy of various
PEG compounds for promoting the alkaline dehydrohalogenation of 2-broaooctane was
issessed. indicated a strong dependence of the catalytic activity upon the number
jf repeating PEG units in the molecule. Of the PEG compounds which »trt assessed
?£G 600. which would correspond to n = 1J.2. or an average aolecular weight oi 600.
ippeared to be the aost effective catalyst at a reaction teaperatuie of SO-C and a
resctioa time ol 2 hours. Pentaeihylene glycol was only slightly less effective,
-irvjally all of the investigations of KOH(NaOH)-PEG dehalogenation reactions which
n-;e teen previously reported in the literature have been involved with pure
ospcunds. It stems certain that the coaplex mixture of halocarbons and various
-ther compounds t-hich would typically be present in an actual hazardous chenical
*as:e material ».ll react with these reagents somewhat differently tt.an pure
nilogenated compounds. Accordingly, an extensive series of experiaents were
accomplished in the present prograa to assess the efficacy of KOK-PEG reagents fo:
destruction of halogenated compounds in a variety of actual waste chemical and/or
;r-cess -ixtures,
A -.ajor porrion of the present study was concerned with a waste chemical
-:"ure which originated froa a pentachlorophenol wood treatment facility located
.r lontana. This waste, which contained about 3.5* pentachlorcphenc 1 in a
-».rcleuB oil bate also contained parts-per-aillion concentrations of various
•^.chlorinated dienio-p-dioxins (PCDDI and dibenzofurans (PCDF). The laboratory
:ttaints whi;; conducted using samples of this waste material entailed the
::liow;nc:
t. Tht cheoici! -»aste sample was stirred vigorously in its container in crdei to
•ix it and rake ilie sacple as honogeneous as possible. Four separate aZiqu;!? of
-he fac,p!e were tt'n removed from the container and transferred tc i:-;w. prc-^). in;d
Mais sirplt bott'es (jttid wjth Teflon-lined lids. Twc- of the e-.alKi tli-jure;.
'.in
aaounting to 0.123 graa each, were not treated with KPEG, but were reserved for
direct analysis, in order to deteraine the concentrations of PCDD/PCDF in the
original waste saaple. One of the larger saaple aliquots. aaounting to 19.82
grass, was treated as described below.
2. To the 19.82 graas of the saaple were added 1.09 graas of solid KOH. The
saaple vessel was then placed in a sand bath (inside a glove box), aaintained at a
teaperature of 35»C. for a period of 30 ainutes. while the contents of the bottle
were stirred continuously. After 30 ainutes had elapsed, the bottle was removed
froa the sand bath, capped, and allowed to cool to ambient teaperature. An aliquot
of the mixture was then removed for subsequent analysis in order to deteraine if
the KOH treatment alone had any effect on the PCDD/PCDF in the saaple.
1. A portion of the KPEG reagent, prepared by heating PEG-400 saturated with solid
KOH pellets, was heated in a water bath at a teaperature of 75*C for a period of 1
hour, with constant stirring during this period. At the end of this tiae, the
solution appeared unifora.
4. While the KPEG reagent was still hot (75'CI. 21.20 graas ot it'were removed
froa the container and ismediately transferred to the bottle containing the
chemical waste saaple to which KOH had been previously added.' The staple bottle
was then returned to the sand bath, aaintained at a teaperature of 10'C. and
continuous stirring of the saaple with a Teflon-coated stirring rod was begun.
5. At intervals of 15, 30. 45. 60, 90, 120 and 480 ainutes following addition of
the KPEG reagent to the waste saaple. saall aliquots of the treated saaple were
removed for analysis. Duplicate aliquots were removed at the indicated tiae
intervals to demonstrate replicability. Immediately after each aliquot was
reaoved, the KPEG reagent contained therein (and any reaction which was still
occurring) was quenched by adding 4 mL of S0\ H2S0«. so that the pH of the solution
was adjusted to pH - 10-11. These aliquots were subsequently subjected tc GC-MS
analyses to deternxne the concentrations of PCDD and PCDF.
A second set of experiments identical to those jumt described, with the
exception that the reaction teaperature was aaintaiaed to 10Q»C. Mas also
accomplished. Suaaariss o£ the results obtained in both sets of experitents under
conditions which yielded optisua dechlorination of PCDD and PCDF are presented in
Tables 1 and 2. These results indicate that KPEG treataent of this waste for a
period of 45 minutes at 70»C results in essentially complete dechlorination (2 99%)
of all PCDD and PCDF. Similar results were obtained within 15 Pinutes following
KPEG treatment at 100*C.
The results of sinlar studies of other hazardous wastes containing PCBs
chlorinated benzenes and other chlorinated phencls wm also be described.
',y>
-------
TABLE 1. CONCENTRATIONS OF PCDD
IN UNTREATED, KOH-TREATED. AND KPEG-TREATED PCP/OIL WASTE SAMPLES
Concentrations in Parts-Per-Billioc
" ople
¦c cntti'-'n
•rr:f.U"?d Oil'
Iriauc Oil*
KOH only 85"/JO nun
Treited Oil- "
45 uia/70'
Treated Oi1* •
15 Tin.MOO'C iO.86) (1.25) (2.091 U.J6)
Total
Total
Total
Total
Toial
2,3,1.8'
Tetra-
Penta-
Hexa-
Hepta-
Ocia-
TCDD
CDO
CDD
CDD
CpD
—-CDD
29.0
455
885
3292
20.405
*1.579
27.6
475
975
J 54 B
19,969
38,597
ND
NO
NO
HD
5.82
NO
(0.64)
(0.31)
(0.64)
(1.38)
(3.*)
ND
ND
ND
ND
2.25
4.4
fierce ot results obtained iro« twc separate analyses.
Trear d with KOH followed by KPEC.
TABLE 2. CONCENTRATIONS OF PCDF
IM UNTREATED. KOH-TREATED. AND KPEG-TREATED PCF/OIL SAKPLES
Concentrations in Parts-Per-_bii 1»on
Total
Total
Total
Total
Total
urplt
>.s:rAp*.icr.
2.3.7.8-
T.cpr
Tetra-
. CDF
P«nta-
CDF
Hexa-
CDF
Hcpta-
?Pf
Octa-
CDF
r.t reVv d Oil*
24-0
138
507
3768
5ie-i
M IS
reattc Oil*
21. S
117
452
3696
4 74u
6370
.OH oni y 2V' •' 30 mi n
Oil* 1
? .-jn/70-
ND
(0.21)
1.59
ND
(0.42!
2.32
4.*-1
HP
l4.36*
i '. uec oi}' f
£. ~i n '; 00° C
5.45
109
ND
(0.60)
2.73
ND
tO.91:
N C
0.15)
A.>-;-j:e of rcsul'f obtained froa two separate analyses.
T. '3!ei tfith >'¦! followed by KFEC.
"PREPRINT EXTENDED ABSTRACT"
Presented Before the Division of Environmental Chemistry
American Chemical Society
Hew Orleans, Louisiana, August 30-Septen<>er 4, 1987
A STUDY OF THIONATION AS A POSSIBLE DETOXIFICATION TECHNOLOGY
John A. Glaser
United States Environmental Protection Agency
Hazardous Waste Engineering Research laboratory
26 U. St. Clair St.
Cincinnati. Ohio 45268
and
William C. von Meyer
Fairview Industries
8616 Fairway Place
Middleton, Wisconsin 53562
Hazardous waste sites in the United States contain a wide variety ana
concentration range of chemical contaminents. The variety of organic chemical
structures encountered extend from simple aliphatics to condensed ring'aromat-
ics. The persistence of some hazardous waste chemicals Is due in part to the
inability of the environment to cleanse itself of these materials. Aromatic
halocarbons are among the more tonic and persistent compounds found.
The simple conversion of halogenated organic* to a non-halogenated hydro-
carbon has been an elusive target for the environmental chemist. Hany of the
ordinary reactions found in the lexicon of the organic chemist that permit this
conversion are not durable for application to an environmental setting and are
not cost-effective. With the organic substrate varying from aliphatics to aro-
matics, it is hard to envision a reaction scheme leading to the desired dehalo-
genation. One possible answer to this need is the use Of sulfur for nucleophilic
displacement of the attached halide. The reaction between p-dichlorobenzene and
sulfur in the presence of sodium carbonate has been shown to lead to displacement
of chloride with the formation of an insoluble polymer (]). The only drawback
was that this reaction apparently requires a significant energy of activation
with normal operating temperatures of 31)0-350 degrees Fahrenheit. This reaction
was reported to occur in the solid state leading to the displacement reaction
below the melting points of either sulfur or the sodium carbonate. Polymer
formation from this reaction has been exploited commercially in the Synthesis
of the Ryton fiber (2,3,4). When the products of this reaction are compared
with starting materials from a toxicological viewpoint, a low molecular weight
potentially toxic halocarbon has been converted to a nonvolatile nontoxic
degradable polymer of essentially low toxicity.
-------
APPENDIX C
SUPPLEMENTARY MATERIAL FOR IN-SITU
BIODEGRADATION OF ORGANIC POLLUTANTS IN GROUNDWATER
Dr. C. Herbert Ward, Rice University, Houston, Texas
-------
Volume 18, Issue 1 (1988) 29
BIORESTORATION OF AQUIFERS CONTAMINATED WITH ORGANIC
COMPOUNDS
Authors: M. D. Lee
J. M. Thomas
R. C. Borden
P. B. Bedient
C. H. Ward
National Center for Ground Water
Research
Department of Environmental Science and
Engineering
Rice University
Houston, Texas
J. T. Wilson
Robert S. Kerr Environmental Research
Laboratory
Subsurface Processes Branch
U.S. Environmental Protection Agency
Ada, Oklahoma
Referee: R. A. Conway
Central Engineering Department
Union Carbide Corporation
South Charleston. West Virginia
I. INTRODUCTION
Ground water is a major source of drinking, industrial, and agricultural water in the U.S.
and a limited resource. Therefore, contamination of ground water by anthropogenic activities
is of dire concern.1 Organic compounds can contaminate aquifers by inadvertent spills,
improper waste disposal techniques, and agricultural practices.2 The widespread distribution
of organic chemicals in ground water and the resulting adverse health effects have prompted
both the public and scientific community to examine the fate of this limited resource.' A
1980 survey of the drinking waters from 39 communities using ground water indicated that
23% of the wells were contaminated with dichloroethylenes and other halogenated aliphatic
compounds. ' Other industrial chemicals such as toluene and phthalate esters have also been
detected in various surveys of ground water quality.
There are a number of techniques available to remediate ground water contaminated with
organic compounds. These include physical containment, in situ treatment with chemicals
or microbes, and withdrawal and treatment via various forms of physical, chemical, or
biological processes.4 Examples of physical containment techniques are excavation and
removal to a secure site, installation of barriers to ground water flow, and hydrodynamjc
control by injection and production wells. In situ chemical treatment involves inactivating
or immobilizing contaminants with chemical agents. In addition to physical coffllainment and
in situ chemical treatment, subsurface pollutants can be treated in situ by stimulating the
native microbial population. Another in situ biostimulation technique which has not yet been
demonstrated is the inoculation of the subsurface with a microbial population that has
specialized metabolic capabilities. Related processes such as the addition of bioemulsifiers
or surfactants to increase the availability of subsurface contaminants to the microflora can
also be used. Contaminated ground water can be withdrawn and treated by physical processes
such as adsorption onto activated carbon or transfer to the gaseous phase by air stripping.
Rcpnnied from the CRC Cnttval Reviews in fcnvimnmcmiil Control, Vol IX. Issue !. pages wvs h\ CRC Pn-ss. |nc
-------
30 CRC Critical Reviews in Environmental Control
chemical processes such as precipitation, oxidation, or reduction reactions, or biological
processes. Combinations of these processes are often more successful than individual Tech-
niques. When applicable, biological treatment may offer the advantage of partial or complete
destruction of the contaminants rather than simply transferring the pollution to another phase
of the environment.
II. IN SITU TREATMENTS
A. Microbial Activity in Aquifers
1. Evidence for Microbial Activity in the Subsurface
Technologies for in situ biorestoration of polluted aquifers have resulted from research
indicating that subsurface microorganisms exist, are metabolically active, and often nutri-
tionally diverse. Most of the research on ground water microbiology was initiated by a
review, published in 1973. by Dunlap and McNabb* of the Robert S. Kerr Environmental
Research Laboratory, which addressed subsurface biological activity in relation to cround
water pollution. Before publication of the review, the concept of biological activity below
the rhizosphere had not been widely received. Microbiologists were skeptical about biological
activity in the subsurface because of the oligotrophy conditions that exist below the rhizosphere"'
and by an early study which indicated that microbial numbers decline precipitously with
depth.7
2. Sampling Methods for Subsurface Microbes
A document that described sampling methods for subsurface microorganisms was pub-
lished in 1977 by the Environmental Protection Agency (EPA)." The method for procuring
a representative sample of unconsolidated subsurface soil has since been modified.4 A soil
sample is collected by first drilling a borehole to a desired depth with an auger and then
taking the sample with a core barrel. After sample procurement, the core is extruded throueh
a sterile paring device that removes the outer layer of soil that has come in contact with the
core barrel. The remaining soil core is thus uncontaminated by the sampling procedure and
is considered to be representative of the subsurface.
Investigations of microbial activity in the subsurface conducted prior to the development
of the sampling techniques were equivocal because of the potential for contamination durine
sample procurement. In addition, many of the investigations were conducted using well
water instead of core material. Recent evidence suggests that the majority of subsurface
microorganisms is associated with soil particles."1 In addition, well water may contain
microorganisms that are artifacts of the well because of subsurface contamination durinu
well installation and changes in water quality around the well.
3. Microbial Numbers in the Subsurface
Methods to enumerate the subsurface microflora also have been developed Electron
microscopy, viable counts, epifluorescence microscopy, and measurements of biochemical
components have been used to estimate microbial biomass." " " in contrast to Waksman's
study.7 which reported that microbial numbers declined with depth, uniform population
levels around 10s to 107 cells/g dry soil, measured by epifluorescence microscopy were
reported for profiles of uncontaminated shallow aquifers." 'However, bacteria in a
chalk aquifer (consolidated) were sporadically distributed with depth." Close examination
of the subsurface strata indicated patchiness of bacterial populations; samples from the top
of the unsaturated zone of an artesian aquifer yielded the highest counts, whereas those from
bedrock and confining layers yielded the lowest total counts.-N
4. Microbial Ecology of the Subsurface
Bacteria are the predominant form of microorganism observed in the subsurface, although
a few higher life forms have been detected/' " " Some eukaryotic forms which may be
-------
Volume 18, Issue 1 (1988) 31
fungal spores or yeast cells have been observed in the upper 10 m of a soil profile.1-:o"
Bacteria, protozoa, and fungi have been detected in samples of ground water collected from
1-year-old wells.-'* In addition, a slow-growing amoeba has been isolated and cultured from
the ground water interface of an uncontaminated soil.1" -4
Organic matter that enters the uncontaminated subsurface is usually the more refractory
humic substances which resist degradation while percolating through the biologically active
soil zone. The organic material available for metabolism by the subsurface microflora is
likely to be present in low concentrations and difficult to degrade. The majority of micro-
organisms present in such nutrient-poor environments is generally oligotrophic. Character-
ization of the subsurface microflora indicates that the bacteria are usually smaller (<1 |xm
in size) than those in eutrophic environments and both Gram-positive and -negative cell
types are present.13 Gram-positive forms predominate in many uncontaminated soils.The
predominance of small, coccoid cells, and hence a large surface-to-volume ratio for enhanced
nutrient uptake, is a likely mechanism for survival in an oligotrophic environment such as
the uncontaminated subsurface." In contrast, subsurface soil contaminated with creosote
waste was found to contain more biomass and a greater proportion of Gram-negative to
Gram-positive microbes when compared with uncontaminated soil from the same site."-"
5. Metabolic Activity of the Subsurface Microbial Community
Studies have also indicated that many subsurface microorganisms are metabolicaliy active.
Of the total cell count, about 0.01 to 50% can be recovered by plating on solid media and
about 1 to 10% exhibit respiratory activity measured by the reduction of 2-(/j-iodophenyl)-
3-/j-nitrophenyl)-5-phenyl tetrazolium chloride by cytochromes.1618 Microbial activity,
measured by the hydrolysis of fluorescein diacetate, declined with depth in the unsaturated
zone of Ultisols and Alfisols.- however. 2-(/>-iodophenyl)-3-(/?-nitrophenyl)-5-phenyl tet-
razolium chloride reduction varied greatly between strata of a soil profile obtained from a
shallow aquifer.--1
Many subsurface microorganisms are nutritionally diverse (Table 1). Simple substrates
such as glucose, glutamic acid, arginine. a mixture of amino acids, and a synthetic compound,
nitrilotriacetic acid, were mineralized in samples of uncontaminated ground water.-6 Polar
solvents such as acetone, isopropanol. methanol, ethanol. and tert-butanol also have been
reported to degrade aerobically by subsurface microorganisms." -* More challenging con-
taminants that are aerobically degraded by subsurface microorganisms include the methylated
benzenes, chlorinated benzenes,2'' chlorinated phenols,J0 and methylene chloride.:7 Highly
lipophilic compounds such as naphthalene, methylnapththalenes. dibenzofuran. fluorene.
and phenanthrene are also biotransformed in the subsurface.
The microflora in some uncontaminated soils require little or no acclimation period to
degrade many xenobiotics. For example, toluene, chlorobenzene. and bromodichloromethane
were biotransformed in uncontaminated soil, but not 1,2-dichloroethane. 1.1,2-trichloro-
ethane. trichloroethylene, and tetrachloroethylene.M Benzene, toluene, and the xylene isomers
were found to degrade in uncontaminated subsurface soils." In addition, methanol (80 to
100 ppm) was degraded completely after 2 months, whereas tert-butanol degraded much
slower in two uncontaminated anaerobic aquifers.14
In contrast to reports of degradation of xenobiotics added to uncontaminated soil, long
periods of acclimation to subsurface pollutants may be required before biodegradation can
occur. Wilson et al." reported degradation of naphthalene, I-methyl naphthalene. 2-methyl
naphthalene, dibenzofuran, and fluorene at 100 to 1000 pg/t in subsurface soil in the plume
of contamination from a creosote waste pit: however, degradation of these compounds was
not observed in uncontaminated soil from the same site. The time and concentration required
for acclimation of the microflora to subsurface pollutants are unknown. Spain and van Veld"
reported a threshold concentration of 10 ppb for adaptation to p-nitrophenol in samples of
sediment and natural water. A better understanding of acclimation processes may explain
-------
32 CRC Critical Reviews in Environmental Control
Table 1
ORGANIC COMPOUNDS THAT HAVE BEEN
SHOWN TO BE BIODEGRADABLE IN THE
SUBSURFACE
Soil from con-
Compound
Natural compounds
Glucose
Glutamic acid
Arginine
Solvents
Acetone
Ethanol
Isopropanol
tert-Butanol
Methanol
Bromodichloromethane
Aromatics
Benzene
Xylene
Methylated benzenes
Chlorinated benzenes
Chlorinated phenols
Naphthalene
Dibenzofuran
Fluorene
Phenanthrene
Toluene
Chlorobenzene
why some chemicals persist in the subsurface even though they have been reported to degrade
in laboratory cultures and samples of surface water and soil.
6. Environmental Factors Which May Limit Biodegradation
Environmental factors may limit or preclude the biodegradation of subsurface organic
pollutants, even in the presence of adapted organisms. The recalcitrance of compounds
thought to be biodegradable may result from a lack of an essential nutrient, substrate con-
centration, substrate inaccessibility, and the presence of toxicants.'* Transport of contami-
nants in the subsurface also affects biodegradation. Transport is discussed in detail in Section
IV.
Biodegradation of many organic pollutants in the subsurface may be limited by insufficient
concentrations of oxygen. Alexander17 reported that even the metabolism of carbohydrates
may be inhibited in oxygen-depleted environments. Lee and Ward" found that the rate and
extent of biotransformation of naphthalene, 2-methyl naphthalene, dibenzofuran. fluorene,
and phenanthrene were greater in oxygenated ground water than in oxygen-depleted water.
Contrary to general theory that complete degradation (mineralization) of hydrocarbons re-
quires molecular oxygen, more recent research suggests that alternate pathways exist under
anaerobic conditions. Kuhn et al.3Sl reported mineralization of xylenes in samples of river
alluvium under denitrifying conditions. In addition, benzene, toluene, the xylenes, and other
alkylbenzenes were metabolized in methanogenic river alluvium that had been contaminated
with landfill leachate;"1 mineralization of toluene was confirmed by adding uC-labeled
toluene and measuring the amount of uCO: produced. Gfbic-Galic and VogelA"a)so reported
mineralization of toluene and benzene under anaerobic conditions by a methanogenic con-
sortium acclimated to ferulate. Further tests indicated that water supplied the oxygen that
is first incorporated into the monoaromatic compounds.""'
laminated
area Aerobic Ref.
No Yes 26
Yes Yes 27
Yes Yes 28
No Yes 9
No Yes 33
Yes Yes 29
Yes Yes 30
Yes Yes 31.32
No Yes 9
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Volume 18, Issue 1 (1988) 33
The presence of oxygen may inhibit the biodegradation of many halogenated aliphatic
compounds in the subsurface. Degradation of trihalomethanes. trichloroethylene. and tet-
rachloroethylene did not occur in aerobic cultures of sewage bacteria; however, the trihal-
omethanes were degraded anaerobically by mixed cultures of methanogens.41 In addition,
Bouwer and McCarty4- reported that chloroform, carbon tetrachloride, and brominated tri-
halomethanes, but not chlorinated benzenes, ethylbenzene, or naphthalene, were biotrans-
formed under denitrifying conditions.
In addition to oxygen, other nutrients may limit the biodegradation of organic pollutants
in the subsurface. Inorganic nutrients, such as nitrogen and phosphorus, may be limiting
when the ratios of carbon to nitrogen or phosphorus exceed that required for microbial
processes. On the other hand, the presence of sulfate may inhibit methanogenic consortia
that have been reported to dehalogenate and mineralize many chlorinated aromatic
compounds.>0-45
The effect of substrate concentration on biodegradation of organic compounds in surface
soils and waters has been documented.44 Thresholds below which degradation is slow or
does not occur may exist for compounds that are readily biodegradable at higher concen-
trations. Boethling and Alexander45 reported that 10% of 2.4-dichlorophenoxyacetate at
concentrations of 22 pg/m£ and 2.2 ng/mf was mineralized in stream water, whereas about
80% was mineralized at higher concentrations of 0.22 and 22 |xg/m^. On the other hand,
microorganisms may be inhibited or killed by high concentrations of organic pollutants that
result from injection wells and hazardous waste sites. Lee46 reported that glucose mineral-
ization was inhibited in subsurface soil heavily contaminated with creosote; however, glucose
was mineralized in uncontaminated and slightly contaminated core material from the same
site.
Other factors such as sorption, pH, and temperature may also affect biodegradation of
pollutants in the subsurface. Many of the organic compounds contaminating the subsurface
are highly lipophilic. These compounds are sorbed by soil more strongly than the more
hydrophilic compounds.47 Sorption may enhance degradation by concentrating nutrients or.
conversely, may prevent degradation by rendering the substrate unavailable to the microor-
ganism. Zobeii4" reported that sorption of organic material to solid surfaces in dilute nutrient
solutions increased microbial respiration. In contrast. Ogram et al.4" observed that 2-4
dichlorophenoxy acetic acid sorbed to soil was completely protected from microbial deg-
radation. Therefore, sorption may be important in nutrient scavenging in uncontaminated
aquifers which are generally oligotrophic; however, sorption may compete with the micro-
flora for subsurface pollutants that are relatively hydrophobic.
The soil pH may affect sorption of ionizable compounds in addition to limiting the types
of microorganisms in the subsurface. Methanogens. which have been implicated in miner-
alization of some aromatic hydrocarbons, are inhibited at pH values less than 6. v' Nitrifi-
cation, the microbial conversion of ammonia to nitrate, is also limited at pH values below
6 and is negligible below 5. Hambrick et al." also reported that mineralization of octadecane
and naphthalene in sediment was faster at a pH of 8 than 5.
Temperature also influences microbial metabolism of subsurface pollutants. The temper-
ature of the upper 10 m of the subsurface may vary seasonably; however, that between 9
to 18 m approximates the mean air temperature (between 3 and 25°C in the U.S.) of a
particular region." Biodegradation of subsurface pollutants in the more northern climates
may therefore be limited by cooler temperatures. Bartholomew and PfaenderM reported that
the microbial metabolism of m-cresol. nitrilotriacetic acid, and chlorinated benzenes in fresh
water and estuarine areas decreased as temperature decreased. Atlas"4 and Mulkins-Phillips
and Stewart" also reported a direct relationship between petroleum hydrocarbon degradation
and temperature.
In summary, the subsurface environment contains microorganisms that degrade many of
the organic compounds that contaminate ground water. The subsurface microflora in un-
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34
CRC Critical Reviews in Environmental Control
contaminated aquifers is probably oligotrophy. The majority of the microorganisms is as-
sociated with soil particles. Even in the presence of adapted populations, environmental
factors such as temperature. pH. dissolved oxygen levels, inorganic nutrient concentrations,
and the availability and concentration of the organic contaminants may limit biodegradation
of subsurface pollutants.
B. Biostimulation by Addition of Limiting Nutrients
1. Development of the In Situ Biostimulation Process with Oxygen Supplied by Air Sparging
a. Application of the Degradative Activity of Subsurface Microbes
The potential for biodegradation of organic compounds in contaminated aquifers was first
recognized in 1971. Williams and Wilder"' observed that ground water contaminated with
gasoline from a leaking pipeline in the Los Angeles-Glendale. Calif., area contained bacteria
that degraded hydrocarbons; however, studies indicated that biodegradation of the gasoline
was limited by the availability of oxygen, mineral nutrients, and hydrocarbon surface area.
These investigators suggested that the hydrocarbon-degrading bacteria could be used to clean
the aquifer of residual gasoline; however, concern was expressed that bacterial growth would
plug the well and formation during the process. McKee et al." conducted bacteriological
investigations using soil, water, and bacteria from the Los Angeles-Glendale. Calif., site
and found several species of Pseudomonas and Arthrobacter that could degrade gasoline.
The total number of gasoline-degrading bacteria in the ground water numbered over 50.000
cells/m{ in the contaminated zone, but less than 200 cells/m{ had been found in the un-
contaminated wells and in wells where gasoline had not been detected for a year. The
presence of high numbers of gasoline-degrading bacteria was suggested as an indicator of
cleanup progress. Column studies designed to investigate the fate of gasoline trapped in the
pore space of soil from the site indicated that the bacteria rapidly degraded the gasoline in
the zone of aeration but slowly degraded that in the saturated zone. In a similar study.
Litchfield and Clark™ enumerated hydrocarbon-degrading bacteria in ground waters from
12 sites which were contaminated with petroleum. The numbers of hydrocarbon-degrading
bacteria ranged from 10' to 10" cells/m<, with similar numbers of both aerobic and mf-
croaerophilic organisms, in ground waters containing more than 10 ppm hydrocarbon. Hv-
drocarbon-degrading bacteria were found in ground water from all 12 sites; however, on a
site-by-site basis, there were no relationships between the types of organisms, the type of
petroleum contamination, the geological characteristics, or the geographical location of the
site.
Application of the degradative capacity of subsurface microorganisms to restore gasoline-
contaminated ground water was first demonstrated by Raymond. Jamison. Hudson, and co-
workers at Suntech.¦w In 1974, Raymond"1' received a patent on a process designed to remove
hydrocarbon contaminants from ground waters by stimulating the indigenous microbial
population with nutrients and oxygen. The process involves circulating oxygen and nutrients
through the aquifer using injection and production wells. Placement of the wells is dependent
on the area of contamination and the porosity of the formation, but usually they are no
closer than 100 ft apart. The nutrient amendment consists of nitrogen, phosphorus, and other
inorganic salts, as required, at concentrations that range from 0.005 to 0.02% by weight;
oxygen is supplied by sparging air into the ground water. The process is projected to require
about 6 months to achieve degradation of 90% of the hydrocarbons provided that the growth
rate of the microorganisms was 0.02 g/t per day. The numbers of bacterial cells are expected
to return to ambient levels after terminating the addition of nutrients. Cleanup efficiencies
are highest for ground water contaminated with <40 ppm gasoline.
b. First Application of the Biostimulation Process
The biostimulation process patented by Raymond was first demonstrated at the site of a
pipeline leak in Ambler. Penn. An estimated 380,(HX) i of high octane gasoline had leaked
into a highly fractured dolomite outcrop underlaid by quartzite.''1 The depth to the water
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Volume 18, Issue I (1988) 35
table ranged from 9.2 to 30.5 m in the 46 monitoring wells installed at the site. Before
biorestoration was attempted, remedial action consisted of conventional pump and treat
technologies. The gasoline was contained by continuously pumping water from \\;ells located
in the spill area. About 238,000 I of the gasoline was recovered by physical methods;
however, recovery was incomplete and approximately 119,000 £ of residual gasoline re-
mained. The concentration of dissolved gasoline in the withdrawn ground water averaged
<5 ppm. The time required for remediation of the aquifer using this pump and treat technique
was estimated to be more than 100 years.
During the initial phases of remediation, problems in analyzing the concentration of
residual hydrocarbons were encountered.61 These problems were later attributed to gasoline
degradation by bacteria in the ground water. A program designed to investigate the potential
for biodegradation of the gasoline by these organisms was then initiated. A laboratory study
indicated that supplements of air. inorganic nitrogen, and phosphate salts could increase the
numbers of hydrocarbon-degrading bacteria by 1000-fold."2 Small-scale field studies also
indicated that nutrient additions would enhance the growth of bacteria that degrade hydro-
carbons. by A full-scale program to stimulate biodegradation of the gasoline in the aquifer
was then initiated.The nutrient amendment, which contained ammonium sulfate, disodium
phosphate, and monosodium phosphate, was injected into the aquifer as a 30f/c concentrate
by batch addition. Biodegradation of 1 t of gasoline was estimated to require 44 g of
nitrogen, 22 g of phosphorus, and 730 g of oxygen. Batch addition of the nutrients worked
as well as continuous addition and was more cost-effective; however, high concentrations
of nutrients could osmotically shock the microorganisms. Oxygen was supplied by sparging
air into the wells using paint sprayer-type compressors and carborundum diffusers with a
flow rate of 0.06 m Vmin. As a result of the treatment, the bacterial population increased
from about 10' to I07 cells/m€. High bacterial counts mirrored locations of high gasoline
concentrations at the site."1
During the biostimuiation program at the Ambler, Penn., site, 32 cultures of bacteria that
actively metabolized gasoline were isolated and characterized.64 The isolates included species
of the genera Nocardia, Micrococcus, Acinetobacter, Flavobacierium, and Pseudomonas;
some cultures could not be identified. The results of experiments that investigated the
metabolic capabilities of the isolates suggested that the Nocardia cultures were largely
responsible for the degradation of the aliphatic hydrocarbons, whereas those from the genus
Pseudomonas degraded the aromatics. Gasoline was degraded by a mixed culture from
ground water. However, individual components of gasoline such as branched paraffins,
olefins, or cyclic alkanes did not support the growth of any isolate.
The bioreclamation program conducted by Suntech in Ambler, Penn.. was reasonably
successful. During the period of nutrient addition, the concentration of gasoline in the ground
water did not decline; however gasoline could not be detected in ground water 10 months
later." A 1000-fold increase in the numbers of total and hydrocarbon-degrading bacteria
was observed in ground water from many wells."' The waters from some wells exhibited
foaming because of high microbial numbers and associated exopolysaccharides. Counts of
microorganisms determined I year after the nutrient addition was terminated indicated that
the microbial population had declined. Estimates based on the amount of nitrogen and
phosphorus removed from the nutrient solution suggested that between 88,600 and 112.400
( of gasoline were degraded. However, this estimate was not particularly accurate because
some of the nutrients may have been adsorbed by the soil or lost from the biostimuiation
area by dilution. In addition, the estimates were based on discrete samples rather than
composited samples. Large quantities of nutrients were used in this project; approximately
79 t of food-grade reagents were purchased.
c. Steps in the Biostimuiation Process
The basic steps involved in an in situ biorestoration program are (1) site investigation.
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36 CRC Critical Reviews in Environmental Control
(2) free product recovery. (3) microbial degradation enhancement study. (4) system design.
(5) operation, and (6) monitoring.4 The first step in the process is to define the hydrogeology
and the extent of contamination of the site. Important hydrogeologic characteristics include
the direction and rate of ground water flow, the depths to the water table and to the
contaminated zone* the specific yield of the aquifer, and the heterogeneity of the soil. In
addition, hydraulic connections between aquifers, potential recharge and discharge areas,
and fluctuations in the water table should be considered. The sustainable pumping rate must
also be determined.6, 66 These parameters can be determined by surveying the existing data
for that site and region, reconnaissance by experienced hydrogeologists, geophysical surveys,
excavation of test pits, and installation of boreholes and monitoring wells.67 Low dissolved
oxygen concentrations may indicate an active zone of hydrocarbon biodegradation.'" The
types and concentrations of contaminants are also important.The type of remedial action
chosen for a particular site depends on the time elapsed since the spill, the areal extent of
contamination, the nature of contaminants, and whether the contamination is acute, chronic,
or periodic. The urgency for action and the treatment level that must be achieved will depend
on the potential for contamination of drinking water or agricultural water wells.
After defining the site hydrogeology, the next step is recovery of free product. Depending
on the characteristics of the aquifer and contaminants, free product can account for as much
as 91% of the spilled hydrocarbon.'" The remaining hydrocarbon, which is sorbed to the
soil and dissolved in the ground water, may account for 9 to 409c of the total hydrocarbon
spilled; the majority is usually sorbed. however, the dissolved phase is the most difficult to
treat. The pure product can be removed using physical recovery techniques which include
(1) a single pump system that produces a mixture of hydrocarbon and water that must be
separated, but requires minimal equipment and drilling; (2) a two-pump, two-well system
which utilized one well to produce a water table gradient and a second well to recover the
floating product; or (3) a single well with two pumps in which a lower pump produces a
gradient and an upper pump collects the free product/ Physical recovery often accounts for
only 30 to 60% of the spilled hydrocarbon before yields decline.w Continued pumping of
contaminated wells may contain a spill.
Prior to in situ treatment, a laboratory study is conducted to determine the nutrient
requirements that will enable the indigenous microorganisms to efficiently degrade the
contaminants.4 Kaufman7" suggested that these laboratory studies can provide a reliable basis
for field trials: however, the studies must be performed under conditions that simulate the
field. For example, Kuhlmeier and Sunderland" conducted a laboratory investigation of the
unsaturated zone using samples saturated with ground water. Clearly, the results of their
study do not represent the fate of the organics in the unsaturated zone. A chemical analysis
of the ground water provides little information about the nutrient requirements of the mi-
croflora.72 However, the chemistry of the site will affect the nutrient formulation. Limestone
and high mineral content soils and ground waters will also affect nutrient availability by
reacting with the phosphorus.7' In addition, nutrients may sorb onto soils, especially silts
and clays, and be unavailable to the microflora.
Laboratory studies conducted to determine appropriate nutrient formulations can be per-
formed using a number of techniques. An increase in the number of total and hydrocarbon-
degrading bacteria has been used to identify limiting nutrients in a factorial experimental
design."73 However, an increase in microbial numbers does not demonstrate that the sub-
strate of interest is being metabolized. Batch culture techniques designed to measure the
disappearance of the contaminant74 and electrolytic respirometer studies designed to measure
the uptake of oxygen also have been used.75 Biotransformation studies which measure the
disappearance of the contaminants or mineralization studies which indicate the complete
destruction of the compound to carbon dioxide and water will confirm that the contaminants
are being degraded. Controls to detect abiotic transformation of the pollutants and tests to
detect toxic effects of the contaminants on the microflora should be included.7h
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Volume 18, Issue 1 (1988)
37
FIGURE I. Typical schematic lor aerobic .subsurface biorestoration.
FIGURE 2. Use of infiltration gallery for recirculation of water and nutrients
in in situ biorestoration.
A system for injection of nutrients into the formation and circulation through the contam-
inated portion of the aquifer must be designed and constructed.4 The system usually includes
injection and production wells and equipment for the addition and mixing of the nutrient
solution.77 A typical system is shown in Figure 1. Placement of injection and production
wells may be restricted by the presence of physical structures. In addition, wells should be
screened to accommodate seasonal fluctuations in the level of the water table. Air can be
supplied with carborundum diffusers."' by smaller diffusers constructed from a short piece
of DuPoni Viaflo tubing.72 or by diffusers spaced along air lines buried in the injection
lines.7* The size of the compressor and the number of diffusers are determined by the extent
of contamination and the time allowed for treatment.77 Nutrients also can be circulated using
an infiltration gallery (Figure 2); this method provides an additional advantage of treating
the residual gasoline that may be trapped in the pore spaces of the unsaturated zone.7"
Oxygen also can be supplied using hydrogen peroxide, ozone, or soil venting (see section
on alternative oxygen sources). Well installation should be performed under the direction
of a hydrogeologist to ensure adequate circulation of the ground water/ Produced water can
be recycled to recirculate unused nutrients, avoid disposal of potentially contaminated ground
water, and avoid the need for makeup water.
Inorganic nutrients can be added to the subsurface once the system is constructed. Con-
tinuous injection of the nutrient solution is labor intensive but may be preferred to batch
addition in some instances. Continuous addition of oxygen is recommended because the
oxygen is likely to be a limiting factor in hydrocarbon degradation.
The performance of the system and proper distribution of the nutrients can be monitored
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38 CRC Critical Reviews in Environmental Control
by measuring the organic, inorganic, and bacterial levels/ Carbon dioxide levels are also
an indicator of microbial activity in the formation.*" Depending on the characteristics of the
nutrients and soil, nutrients can be removed from solution by sorption onto soil.7-1 For
example, about 90% of the ammonium and phosphate and 70% of the hydrogen peroxide
added to a sandy„soil with low calcium, magnesium, and iron was recovered. After passage
of a nutrient solution through a column packed with a clay soil that had high calcium and
magnesium but low iron and chloride levels, 100. 66. and 25% of the ammonium, phosphate,
and hydrogen peroxide were recovered, respectively. However, after passage of a nutrient
solution through a column packed with a clay soil high in calcium, magnesium, and chloride,
but low in iron, 75. 100, and 15% of the ammonium, phosphate, and hydrogen peroxide,
respectively, were recovered. Both soil and ground water samples should be collected and
analyzed to fully evaluate the treatment effectiveness." Raymond et al.6' reported that the
most difficult problem in optimizing microbial growth in the Ambler reservoir was the
distribution of nutrients because of the heterogeneity of the dolomite formation.
d. Additional Case Histories in Which Oxygen was Supplied by Air Sparging
In situ biorestoration has been largely used to treat gasoline spills and with reasonably
good success. However, many of the reports on in situ biorestoration lack sufficient data to
judge fully the overall effectiveness and costs associated with the process.
In a high-permeability sand aquifer contaminated with hydrocarbons in Millville. N.J..
the in situ biorestoration program was successful in removing free product, but residual
hydrocarbons were found at the last sampling period.72 The nutrient solution was transported
through the formation at rates of 2.4 to 4.2 ft/day; aerated water was also injected, but the
dissolved oxygen was rapidly consumed and did not increase in some of the main wells.
However, analysis of core material collected from the aquifer indicated that the concentration
of gasoline had not changed substantially during the biostimulation program. During the
initial treatment process, inadequate dissolved oxygen levels led to the microbial formation
of phenol; however, phenol levels declined as a result of additional aeration. A 10- to 1000-
fold increase in the number of gasoline-utilizing bacteria was noted in the area with the
highest gasoline levels. The cleanup met the state requirement for removal of the free gasoline
and was subsequently stopped.
At a gasoline spill in La Grange. Ore.. 9 months of treatment by in situ biorestoration
and a vapor elimination program succeeded in removing the free product and mitigating the
vapor problems at two restaurants.7* Biodegradation of the gasoline was enhanced by cir-
culating well-aerated ground water amended with inorganic nutrients. After 7 months of
treatment, the concentration of gasoline in soil ranged from 100 to 500 ppm and the average
concentration of dissolved organic carbon in the ground water was 20 ppm. After an additional
3 months of treatment, the dissolved organic carbon levels in the ground water had decreased
to <5 ppm in the majority of the samples.
Fumes released from a pipeline spill of gasoline temporarily closed an elementary school."1
A pumping well was used to maintain the water table below the foundation of the school
and physical recovery was used to remove two thirds of the gasoline. An enhanced biodeg-
radation program was initiated by circulating nutrients and oxygen through the formation
for 6 months. After the cleanup, hydrocarbons could not be detected and the fumes that had
threatened the school had been eliminated.
e. Minimum Hydrocarbon Concentrations Achievable by In Situ Biostimulation
The minimum concentration of hydrocarbon that can be achieved by in situ biorestoration
is unknown and is most likely site specific. A natural gradient field test in a sandy Canadian
aquifer required 434 days to reduce 1000 to 2400 ppb of benzene, toluene, and the xylene
isomers below the detection limits (I to 2 ppb) in the absence of added nutrients and oxygen"
The distribution of dissolved oxygen in the plume was heterogeneous and probably controlled
the biodegradation of the aromatics.
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Volume 18. Issue I (1988) 39
Jensen et al.*2 suggested that the indigenous microflora should be able to reduce the
concentration of hydrocarbons below 1 (xgIt when the initial hydrocarbon concentration is
< 10 mgIt and adequate quantities of nutrients and oxygen are supplied. The results of batch
experiments using ground water from hydrocarbon-contaminated aquifers showed that the
native microflora could generally reduce the concentrations of toluene, benzene, the xylenes,
trimethylbenzene. naphthalene, methylnaphthalene, biphenyl, ethylnaphthalene. and dime-
thylnaphthalene from a range of 400 to 1100 fig It to <1 fig It within I week in the presence
of oxygen and nutrients; however, phenanthrene and toluene persisted at higher concentra-
tions in two of the ground waters after incubation for 6 days.
The concentration of trace-level organics in an aquifer may be reduced by providing a
primary substrate that supports microbial growth and allows the organisms to act upon the
trace-level organics as secondary substrates."1 The concentration of the trace organic or
secondary substrate is thought to be below the minimum substrate concentration (S|llm)
required to support microbial growth."'4 The Sm,„ concept was developed to describe limi-
tations related to transport of organics into a biofilm and the subsequent kinetics of reaction.
There are several examples of S„„n. A reactor-fed laboratory-grade water containing 0.59
mg/< total organic carbon (TOC) was able to reduce acetate below the Smin value (0.03 nig
t) for acetate. Shimp and Pfaender" demonstrated that the addition of fatty acids, carbo-
hydrates, and amino acids enhanced the ability of mixed microbial populations to degrade
substituted phenols. These data suggest that the addition of naturally occurring substrates
may enhance the biodegradation potential of some xtjnobiotics. However, the addition of a
primary substrate may not support the removal of some compounds. A biofilm supported
by thymine could utilize alanine and acetate, both common metabolites, but not phenol and
galactose.54
/. Combination of In Situ Biostimulation with Treatment Processes
In situ biorestoration has been successfully combined with other treatment processes to
reduce organic contaminants in aquifers. In most cases, the contaminated ground water is
withdrawn, treated by a physical, chemical, or biological above-ground treatment technique,
and then recharged after aeration and addition of nutrients. The role of biorestoration in
combination treatment schemes is often difficult to assess. Yaniga et al.*" described the
cleanup of a gasoline spill in which an air stripper was used to reduce the contaminants in
the withdrawn ground water and to supply oxygen before the water was recirculated to the
aquifer via an infiltration gallery. Before recirculation, ammonium chloride, sodium mon-
ophosphate, sodium diphosphate, iron sulfate, and manganese sulfate were added in slug
batches to the treated water. Additional oxygen was supplied by sparging air into the wells.
As a result, the dissolved oxygen increased from a range of 0—5 to 5—10 ppm; (he
hydrocarbon degrading bacteria increased from 10-—10' to 10'—104 cells/m{ with just
oxygen addition by air stripping and sparging and then increased to 10" cells/m* with nutrient
addition and additional oxygen. Brown et al.*7 identified another gasoline-contaminated
aquifer which was treated using air sparging. An estimated 95,000 to 114,000 I of gasoline
entered a 6.1-m thick coarse grain sand and fine gravel aquifer. Recovery of free product
accounted for 70,000 t of the spilled gasoline; however, an estimated 38.000 t was sorbed
to the soil at concentrations of 2000 to 3000 ppm, and 30 to 40 ppm was dissolved in the
ground water. The concentration of gasoline was reduced to <50 ppm in the soil and less
than I ppm in the ground water by air sparging. Only I to 2 ppm of dissolved oxygen could
be achieved in the wells by air sparging.
Ground water contaminated by a spill of four solvents— methylene chloride, n-butanol.
acetone, and dimethylaniline— into a glacial till aquifer was withdrawn and treated by an
activated sludge process. After the sludge settled, the treated ground water was recirculated
into the subsurface through injection trenches after being aerated and amended with nu-
trients.27 The recharge water contained organisms acclimated to the solvents in addition to
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40 CRC Critical Reviews in Environmental Control
a nutrient amendment containing nitrogen, phosphate, magnesium, sulfate, carbonate, man-
ganese, and iron. Additional oxygen was supplied to the aquifer using a series of injection
wells. Removal efficiencies of methylene chloride, n-butanol. and acetone were >979c and
the dimethylaniiine levels were reduced by >93% in the above-ground treatment. The
concentrations of the solvents in the resulting effluent decreased to 0.04 ma/f for n-butanol.
0.92 mg/f for methylene chloride, 0.18 mg/( for dimethylaniiine, and 1.12 mg/{ for acetone
from initial concentrations of 19.1, 58.5, 2.9. and 38.8 mg/£, respectively. Based upon
chemical oxygen demand (COD) and gas chromatography analysis, the plume was reduced
in size by 90% after 3 years of operation."0 The COD was reduced from 300 to 20 mg/< in
one monitoring well. Based on the rate of ground water flow, this reduction in COD coincided
with the expected arrival time of the treated ground water at that well. Elevated levels of
carbon dioxide in ground water collected from the treatment zones, in comparison to those
observed in uncontaminated and decontaminated wells, suggested that in situ biorestoration
was occurring. However, the solvents were detected in the ground water beyond the projected
date for completion of the project and the New Jersey Department ot' Environmental Pro-
tection standards had not been achieved after 3 years ot operation.
Flathman et al." and Quince et a!.*1' discussed cleanup of a methylene chloride spill using
physical and biological above-ground treatment processes and in situ biological treatment.
Following sand filtration to remove particulates, air stripping combined with a heat exchanger
to improve stripping efficiency was initially used to treat the withdrawn ground water: the
water was used then to flush the soil/* Air stripping removed about 98 to 99.9<7r of the
methylene chloride in the withdrawn water. The concentration of methylene chloride in the
ground water in one downstream monitoring well was reduced by 977c. Enhancement of
biodegradation by ammonia and phosphate amendments was used to further reduce the
concentration of the methylene chloride. An activated sludge unit was seeded with acclimated
organisms from a wastewater treatment plant receiving methylene chloride and these or-
ganisms were used to inoculate the soil." After 43 days of in situ biological treatment, the
concentration of methylene chloride in ground water from a monitoring well 6 m from the
spill declined from 192 to 6 ppm. and 156 ppm chloride was released; however, it could
not be determined whether the added bacteria or indigenous microflora or both were invok ed
in methylene chloride degradation. Both air stripping and biological treatment removed
99.9% of the initial amount of methylene chloride during the 4 months of field operation.
The concentration of methylene chloride was reduced from 20.000 to < I ppm in the source
wells.*"
The subsurface at the Naval Air Engineering Center in Lakehurst. N.J.. was contaminated
with ethylene glycol that resulted from the loss of about 4000 gal of cooling water from a
lined surface storage lagoon.7" The unsaturated zone was contaminated with concentrations
of ethylene glycol as high as 4900 mg/kg soil, whereas the concentration of ethylene glycol
in the ground water was 2100 mg/(. The highly contaminated soils were treated using
injection and recovery wells, whereas the ground water contaminated with ethylene glycol
was treated by an above-ground activated sludge unit and by adding ethylene glycol-degrading
bacteria and nutrients to the subsurface. A biofeasibility study using an electolytic respi-
rometer had demonstrated that the concentration of ethylene glycol could be reduced to <50
ppm within 10 days by the natural microflora in the ground water and that the concentration
of ethylene glycol at 1300 ppm was not toxic. The initial operational phase was designed
to degrade as much of the ethylene glycol as possible by treatment above ground with an
activated sludge unit. The effluent from the activated sludge unit was amended with oxygen,
nitrogen, and phosphorus, adjusted to neutral pH. and then reinjected into the subsurface
to create a closed-loop system. The amended effluent was used to flush the contaminated
soil and inoculate the ground water with nutrients and acclimated bacteria. The concentration
of ethylene glycol in ground water collected from the plume recovery wells was reduced
from 420 to 690 ppm to <50 ppm within 26 days;"" however, the unsaturated zone still
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Volume 18, Issue 1 (1988) 41
contained pockets of ethylene glycol. A passive treatment system which involved adding
lime and diammonium phosphate to the soil surface continued after termination of the active
biorestoration phase. By the end of the treatment program, ethylene glycol could not be
detected (detection limit, 50 ppm) in ground water collected from the production wells.
A shallow basin comprised of sand and pea gravel was contaminated with isopropanol
and tetrahydrofuran.74 In addition to isopropanol and tetrahydrofuran, acetone was also
detected in the ground water and was believed to be a byproduct of isopropanol degradation.
Remedial action consisted of a recovery system, treatment in an above-ground biological
reactor, and recharge of the aquifer with the effluent from the reactor which created a closed-
loop system. The effluent, which contained acclimated bacteria, was also amended with
nutrients before reinjection into the subsurface. The soils were flushed with the treated
ground water to remove sorbed organics and introduce acclimated organisms into the aquifer.
Maximum concentrations of isopropanol (950 ppm) and acetone (190 ppm) were detected
in ground water from a centrally located well as a result of flushing pockets of contamination
from the subsurface. The concentration of acetone in the ground water increased initially
until the majority of the isopropanol had been degraded, and then it declined to <0.2 ppm.
Extrapolations from the data indicated that 99c!c of the contaminants would be removed
within 33 days. Estimated cost for removal and disposal of 5700 ml of contaminated soil
was $550,000. whereas the biological treatment program was estimated to cost one fifth as
much.
Winegardner and Quince'*1 documented two case histories of in situ biorestoration that
involved the addition of acclimated bacteria. The first case history described the cleanup of
a semi-soluble aliphatic hydrocarbon plasticizer that was spilled during a train derailment.
Recovery wells were used to collect the plasticizer from the subsurface. Later, surface
recharge and shallow injection were used to flush the plasticizer out of the soil; the peak
concentration of the plasticizer was >2000 ppm. This treatment reduced the areal extent of
the contamination after 70 days, in addition to reducing the concentration of the plasticizer.
Air stripping and carbon adsorption were used initially; however, these techniques were
replaced by biological treatment using activated sludge. The water treated by the activated
sludge contained bacteria that were acclimated to degrade the plasticizer and was injected
into the subsurface to enhance in situ biorestoration. The concentration of the plasticizer in
the water treated by the activated sludge was reduced from approximately 1700 to 400 ppm
after clarification; however, the contribution of the activated sludge and in situ microflora
in removal of the plasticizer in the treatment process could not be separated.
The second case history involved contamination of a glacial kame deposit of sand, gravel,
silt, and clay with chloroform from a leaking pipeline. Ground water was withdrawn and
treated with a mixed-media prefilter, an activated sludge bioreactor and settling vessel, and
a heated air stripper. The effluent from the activated sludge bioreactor that contained bacteria
acclimated to degrade chloroform was injected into the subsurface to enhance biorestoration.
The effluent from the air stripper was discharged into a process sewer or into the subsurface.
A forced flushing/recovery system was used to increase the recovery of the chloroform.
Biological treatment followed the physical recovery; however, treatment effectiveness was
not discussed.
2. Alternate Oxygen Sources
The supply of dissolved oxygen may limit in situ biorestoration of hydrocarbons, especially
in low-permeability aquifers.7: Depending upon the temperature of the ground water, only
8 to 12 mgIt of dissolved oxygen can be achieved by air sparging, and incomplete transfer
of oxygen into water may reduce this even further. Using only the oxygen provided by
sparging air into the ground water. 1500 to 5400 pore volumes of air would be required to
completely degrade the hydrocarbon in an aquifer that is 6 ft deep. I acre in size, has a
porosity of 30%, and contains 4000 mg/£ gasoline. "
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42 CRC Critical Reviews in Environmental Control
Alternative sources of oxygen include pure oxygen, hydrogen peroxide, and ozone. Other
methods of supplying oxygen to the subsurface are soil venting or air flooding''- and colloidal
dispersions of air in a surfactant matrix." Concentrations of 40 to 50 mgJ( of dissolved
oxygen can be achieved with pure oxygen: however, pure oxygen is somewhat expensive,
may bubble out of solution before the microflora can use it. and may be an explosion hazard
if handled improperly .y|
a. Hydrogen Peroxide
Hydrogen peroxide, which decomposes to form one molecule of water and one half
molecule of oxygen, also can be used as a source of oxygen (Equation 1).
HA -* H:0 + 1/2 O, (1)
Hydrogen peroxide has great potential as an alternative source of oxygen but is toxic to
microorganisms at species-specific concentrations. Before application of hydrogen peroxide
to the subsurface, the tolerance range of the in situ microorganisms must be determined in
a laboratory experiment. Concentrations of 3% are used as a sterilant and levels as low as
200 ppm can be toxic to microorganisms. Ground water organisms inoculated into sand
columns could tolerate 0.05% hydrogen peroxide, but higher levels were toxic.In a study
designed to investigate the effect of increasing concentrations of hydrogen peroxide on
gasoline biodegradation, the culture acclimated to hydrogen peroxide levels that were grad-
ually increased from 0.05 to 0.27c; however, removal of gasoline was not greatly increased
in comparison to the control without hydrogen peroxide. Microbial counts were higher in
columns in which hydrogen peroxide was incrementally increased than those which received
only 0.059c hydrogen peroxide. These data suggest an oxygen limitation at lower concen-
trations of hydrogen peroxide. Large populations of microorganisms survived high hydrogen
peroxide concentrations better than small populations." In a study in which the oxygen
concentration was varied from 8 to 200 ppm (using air. 607c nitrogen/40% oxygen, pure
oxygen, or a hydrogen peroxide solution), microbial growth and gasoline degradation were
greatest in columns amended with hydrogen peroxide, which provided the highest concen-
tration of available oxygen."1 At concentrations >100 ppm. hydrogen peroxide may degas
to form air bubbles which may block some of the pores in the aquifer. Decomposition of
hydrogen peroxide may also be catalyzed by iron and fluctuations in pH.'w In addition to
comprising part of the nutrient formulation, certain forms of phosphate, such as potassium
monophosphate, can be used to stabilize hydrogen peroxide solutions. To reduce phosphate
adsorption by the soil, a combination of simple and complex polyphosphate salts can be
used.46 Results from a field test in which hydrogen peroxide was used to increase the dissolved
oxygen content of the ground water indicated an increase from 1 to 15 ppm within 70 hr at
a monitoring well located 7.6 m downgrade of the injection well.
Raymond et al.'" received a patent on a process which involves stimulating biodegradation
of organic contaminants in the subsurface with hydrogen peroxide. The patent described
several formulations of nutrient and hydrogen peroxide solutions and processes that can
stabilize the decomposition of hydrogen peroxide, control movement of the solution through
the aquifer, remove metal ions from the subsurface which catalyze hydrogen peroxide
decomposition, and disrupt biofilms that form a0he point of injection. Hydrogen peroxide
decomposition can be controlled by the addition of peroxidase, oxidase, or a transition metal
(iron, copper, manganese, chromium, or other material, including the chelated forms of
these metals). In addition, condensed phosphates can be perfused into the aquifer to deactivate
or remove substances that catalyze hydrogen peroxide decomposition.
Movement of the hydrogen peroxide solution through the formation can be controlled by
hydratable polymeric materials, interlace modifiers, and densifiers.1" The hydratable poly-
meric materials, such as polysaccharides, polyacrylamides. and polyacrylamide copolymers.
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Volume 18, Issue I (1988) 43
increase the viscosity of the solution. An increase in viscosity reduces the rate of diffusion
and slows the movement of the solution. The addition of surfactants will decrease the
interfacial tension, prevent clays from swelling, disperse materials throughout the zone of
contamination, and decrease the metal-catalyzed decomposition of hydrogen peroxide. For
example, the zone of treatment can be extended into the capillary zone by adding soluble
orthophosphoric salts and condensed phosphoric acids to increase the capillary rise of the
aqueous solution. Salts, such as sodium chloride, calcium chloride, and sodium bromide,
can be used to change the density of the nutrient solution. Biofouling can be controlled by
adding high concentrations (0.5 to 3%) of hydrogen peroxide; the effectiveness of hydrogen
peroxide in controlling biofouling may be enhanced by the addition of dilute acid.
Hydrogen peroxide has been used to enhance the oxygen supply in the subsurface in many
remedial programs. In most cases, the additional oxygen was required to degrade hydro-
carbons in aquifers contaminated from gasoline spills. One case study involved the contam-
ination of a relatively impermeable soil (ground water movement. 0.6 to 0.9 m/year) with
gasoline.'"' About 50 to 60r<- of the free product was recovered', however, concentrations of
hydrocarbon in the range of 3700 to 7200 ppm remained sorbed to the soil. A feasibility
study was conducted to identify an in situ microbial population capable of degrading the
hydrocarbons when supplied with nutrients and oxygen. Hydrogen peroxide was used as the
source of oxygen. After 2 months of operation, free product recovery reached a maximum
of 95 to 114 i/day. numbers of hydrocarbon-degrading bacteria increased one to three orders
of magnitude, and the concentration of sorbed product declined to a range of 2300 to 2900
ppm.
In another in situ biorestoration program designed to clean up gasoline from a leaking
underground storage tank, oxygen was initially supplied by air stripping and sparging and
then by hydrogen peroxide. A layer of heavy silt loam which was underlaid by a layer of
fractured shale and siltstone was contaminated by the spill.w The gasoline infiltrated into
the ground water and the resulting plume, containing dissolved hydrocarbons, contaminated
12 domestic water wells with concentrations ranging from <10 ppb to 15 ppm. Ground
water was withdrawn and an air stripper was used to remove volatile organics and add
oxygen: the oxygenated water was then recirculated into an infiltration gallery to facilitate
removal of the trapped organics. Air stripping reduced the dissolved organics in the effluent
to <0.1 ppm. Additional oxygen was introduced by sparging air through the 6.1- to 9.1-m
water column in the wells. The initial dissolved oxygen levels in the contaminated zone
were 0 to I mg/{, whereas those in the uncontaminated wells were 7 to 9 mg/{. Dissolved
oxygen levels rapidly increased on the periphery of the plume; after 6 weeks of air sparging,
the concentration of dissolved oxygen increased to 3 to 5 mg/f in the contaminated zone.
The nutrient solution included ammonium chloride, sodium phosphate, and various mineral
salts. Existing monitoring wells were used to add the nutrients because nutrient diffusion
was slower than desired. In the first 20 months of treatment, the concentration of dissolved
hydrocarbon was reduced by 50 to 85%, but treatment was continued because significant
levels of hydrocarbon remained. After this treatment period, reduction in the concentration
of dissolved hydrocarbon was minimal during the next 11 months and believed to be a result
of inadequate oxygen supply;'*' in addition, a biofilm had developed and plugged the injection
wells."*
To increase the concentration of dissolved oxygen, a triaT experiment using hydrogen
peroxide was conducted in which 18.9 t of 100 ppm hydrogen peroxide was added to an
injection well 12.2 m from a pumping well.''" As a result, the dissolved oxygen content in
the ground water collected from the pumping well increased from 0.5 to 8 ppm in 24 hr
with a concomitant increase in microbial activity. Then 100 ppm hydrogen peroxide was
added to the infiltration gallery and injection wells to increase the concentration of dissolved
oxygen in the formation. Addition of hydrogen peroxide also controlled growth of the biofilm
on the screens ot the in jection wells. After addition of hydrogen peroxide, the concentration
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44 CRC Critical Reviews in Environmental Control
of hydrocarbons in the ground water had been reduced from 15 to 2.5 ppm. Continuation
of this treatment removed the dissolved hydrocarbons in ground water trom 8 of the 12
wells. Between 200 and 1200 ppb remained in the other four wells.""
Hydroeen peroxide-assisted biodegradation followed by granular activated carbon (GAD
polishing was used to treat a spill of waste solvents and fuel.71"1"1 The source of the con-
taminat.cn was an excavated area around several leaking tanks at a laboratory facility. The
fill material and soil surrounding the storage tanks were contaminated with a mixture of
hydrocarbons composed of xylenes, benzene, toluene, ethylbenzene. and C4-C,: alkanes that
ranged in concentration from 1000 to 3000 ppm. About 2600t of free product was recovered
using a sump pump; however, an estimated 1100 to 3400 ( of the hydrocarbon remained.
The subsurface consisted of sand and sandy clay with fairly rapid ground water flows. The
total number of bacteria in the well water ranged from 300.000 to 420.000 cells/m<: hy-
drocarbon degraders ranged from 5400 to 6100 cells/*. Carbon adsorption and enhanced
bioreclamation were considered for remedial action. Carbon adsorption was estimated to
reouire 10 to ^0 vears and cost $470,000 to $850,000. whereas enhanced bioreclamation
wa^ estimaleti'lo require 4 to 8 momhs and cosl $180,000 .0 $270.000.« Enhanced bio-
reclamation was chosen and the process design consisted of four mjecuon wells and a
Dumping well with a flow rate of 57 to 95 {/rain.'00 A nutrient solution consisting of
ammonium chloride and sodium phosphates was injected by batch addition. Hydrogen per-
oxide was injected continuously following a short period during which only nutrients were
added- addition of nutrients without oxygen had little effect because of the(initial low
dissolved oxygen content (0.8 ppm). After 72 days. 440 kg of nutrients and 945 * of the
hvdroeen peroxide solution had been added. The number of hydrocarbon-degrading micro-
organisms increased 130-fold and the concentration of dissolved oxygen m the ground water
increased to 10 5 ppm after the biorestoration program was initiated. The concentration of
hydrocarbon decreased from 22,700 to 581 ppb in 44 days and to nondelegable levels in
one monitoring well after 72 days. Elevated concentrations of contaminants detected m
another monitoring well were thought to be a result of a leaking line. An estimated 570 to
1500 t of the mixed fuels and solvents had been degraded.'* However, the formation became
nartiallv clogged after 72 days of operation. Clogging of the formation may have resulted
from the movement of silt and degradation of the cement that lined the storage tank vault.7"
An activated carbon system was then used as a polishing step to reduce the hydrocarbon
concentration below 10 ppb in the tank vault and soil.
ThP for a 6- to 18-month bioreclamation program at the laboratory facility was
estimated between $180,000 and $270,000.** Estimates were $50,000 to $75,000 to start
the bioreclamation process and SI30.000 to $220,000 for services and nutrients. The cost
for excavation was estimated between $600,000 and $1.5 million, and the program was
Liected to take less than 6 months; however, facilities on the site would restrict excavation.
Withdrawal and treatment by carbon absorption was estimated to cost $470,000 to $850,000
and reauire 10 to 20 years because of limited extractabUity of the contaminants.
A less successful demonstration of enhanced bioreclamation using hydrogen peroxide was
renorted bv Brown and Norris.,(" A formation consisting of silt, sand- and gravel deposits
w^s contaminated by a spill of 303.000 * of unleaded gasoline. Two subsurface zones were
identified in the test area: (1) a fine quartz sand with some limestone and dolomite grains
Ind ferromagnesium minerals with traces of Umonite and pebbles of dolomite, limestone.
Ld cranite and (2) another zone of fine quartz sand with large amounts of fines and silt
which impeded ground water flow. The hydraulic conductivity ranged between 8.8 to 15.2
x 10 4 cm/sec A free-product recovery program was implemented; however, between 300
and 10 000 opm of hydrocarbon remained in the soil and 50 to 60 ppm remained in the
eround water after 5 years. The concentration of total hydrocarbons in the cores averaged
5477 pprn with a range of 4823 to 6331 ppm for several groups. The highest concentrations
were detected at the water table at depths of 7.3 to 7.9 m. The treatment zone was estimated
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Volume 18, Issue 1 (1988) 45
to contain 6100 ± 2500 (SD) kg of gasoline. Ambient nutrient levels in the ground water
were <1 ppm and the dissolved oxygen content was <0.4 ppm. Total counts and counts
of hydrocarbon-degrading bacteria grown on nutrient agar were 1.2 x 10' and 2 x 10:
cells/g. respectively. Biostimulation was tested in a section of the plume surrounded by two
triangular patterns of monitoring wells which surrounded an inner infiltration gallery. Nu-
trients were batch fed to the inner gallery and then followed by addition of hydrogen peroxide
solutions which were gradually increased from 0 to 500 ppm. Phosphorus levels reached
100 to 250 ppm in the inner gallery and ranged from 1 to 10 ppm outside the gallery. The
concentration of nitrogen ranged from 100 to 250 ppm in the inner gallery and from 10 to
50 ppm outside of the gallery. Total bacterial counts reached 10" cells/mf in the inner gallery
and 6 x 10-' cells/m€ outside of the gallery; the number of gasoline-utilizers also increased.
The concentration of hydrocarbon in the soil was measured after 0. 32. 91. and 164 days
during the test and at depths of 7, 7.6. 8.2. and 8.8 m below the land surface."" During
the test, the concentration of hydrocarbon was reduced from 5490 to 1874 ppm (65%).
Removal of hydrocarbons was highest (from 5643 to 1743 ppm) in the inner gallery near
the injection area, whereas a low-permeability zone was less effectively treated because of
reduced circulation of nutrients. In addition, the concentration of total hydrocarbons was
reduced by 63% outside and between the galleries. The hydrocarbon concentration at the
water table was reduced from 6087 to 4058 ppm and from 2946 to 1008 ppm immediately
below the water table. The data indicate that substantial quantities of hydrocarbons remained
adsorbed onto the soil after in situ biostimulation, although more improvement may have
occurred with continued treatment.
A field demonstration of in situ biorestoration using hydrogen peroxide in a very gravelly
clay loam was adversely affected by the low permeability (3.9 x 10~5 to 3.3 x 10"1 cnV
sec) of the soil.'02 The heterogeneity of the soil and distribution of the contaminants made
it difficult to inject nutrients and pump water. The contamination resulted from a disposal
pit containing chromium sludges, electroplating wastes, chlorinated solvents, cresols. chlo-
robenzenes. and other compounds. "" I(M The organic compounds that were identified included
tetrachloroethyJene. trichloroethylene, trans-1 ,2-dichloroethylene. and o- and p-dichloro-
benzene. Heavy metals present at concentrations >10 mg/£ included antimony, chromium,
copper, lead, nickel, and zinc, and the concentrations of silver, cadium, and mercury were
high in some locations."" 104 The formation consisted of gravel lenses and layers of fine-
grained soils with low hydraulic conductivities. The water table was perched, only 1.2 to
2.4 m thick, and exhibited seasonal fluctuations. Direct microbial counts in soil ranged from
7.6 to 170 x 10" cells/g (wet weight); viable counts ranged from <100 to 7 x 10" cells/
g on both rich and poor media. Laboratory studies conducted under aerobic conditions
indicated that the chlorobenzenes, hydrocarbons, and aromatics could be biodegraded. The
total resolved hydrocarbons, i.e., the organic contaminants separated by gas chromatography
and thought to represent n-alkanes. were reduced more rapidly in the aerated microcosms
than in those supplied with hydrogen peroxide, which may indicate hydrogen peroxide
toxicity. Unresolved hydrocarbons representing branched alkanes were removed under aero-
bic but not anaerobic conditions. The results from these microcosm studies suggested that
biological degradation was feasible, but the heterogeneity of the subsurface and the contam-
inants present seriously limited application of the biorestoration process. The presence of
heavy metals was not expected to prevent biodegradation. but the treatment process could
induce metal mobilization.
The treatment system design for in situ biorestoration consisted of nine extraction and
four injection wells that were connected to a central surge tank and a distribution box.""
One upgradient and two downgradient wells were installed to monitor the influence of the
treatment in untargeted areas. Nutrients were added 2 weeks before the hydrogen peroxide.
After 2 months of treatment, the effectiveness of the treatment could not be determined
because of a change in analytical methods; however, a number of problems were noted with
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46 CRC Critical Reviews in Environmental Control
the field demonstration. Hydrocarbon levels increased in the ground water for unknown
reasons. In addition, the nutrient solution precipitated initially when added on a continuous
basis; the precipitation problem was reduced by switching to batch amendments. The tem-
perature in the well water increased and fluctuated because the impermeable soil could not
sustain flow adequate to prevent the pumps from overheating. Microbial numbers in the
infiltration zone remained low. perhaps due to hydrogen peroxide toxicity. Antimony and
lead may have been mobilized within the aquifer and the nutrients had not reached most of
the wells at the time of this report.1"6
Continued treatment for 6 months resulted in decreases in the levels of chlorobenzene
and total hydrocarbons.107 The breakthrough of the nutrient solution was rapid in the highly
permeable zones, but poor in the less permeable strata. Elevated concentrations of carbon
dioxide were detected in the treatment zone which suggested an increase in microbial activity.
However, the concentration of many of the organic compounds did not decline and biores-
toration of the site was not successful.
b. Ozone
In addition to hydrogen peroxide, ozone (O,) can be used as an alternate source of oxygen.
Ozone was used in an in situ biorestoration program to remediate a hydrocarbon spill in a
railroad yard in Karlsruhe. F.R.G.'"'1 The presence of organic contaminants in the drinking
water wells for the city of Karlsruhe was traced to the hydrocarbon spill in the train yard.
The concentration of organics. iron, and manganese in the ground water increased but the
dissolved oxygen content decreased. The water was withdrawn, treated with 1 g of ozone
per gram of dissolved organic carbon for 4 min and then reinjected into the formation through
five infiltration wells at a rate of 80 to 120 rn'/hr. Supplemental nutrients were not added.
The purified water formed a barrier to prevent further contamination of the withdrawal well.
The ozone treatment increased the dissolved oxygen levels in the ground water which
stimulated the microbial population and enhanced the degradation of the contaminants in
the aquifer. The maximum efficiency of introducing dissolved oxygen into the ground water
was 80% of the initial concentration of ozone. Oxygen consumption by the indigenous
microbes reached approximately 40 kg/day. The dissolved organic carbon decreased from
a range of 2.5 to 5.5 g/m* to a steady-state value of slightly more than 1 g/m\ few mineral
oil hydrocarbons remained. The levels of iron and manganese were also reduced. Although
the total number of bacterial cells increased, microbial counts on media which selected for
disease-causing organisms did not increase. The removal of the hydrocarbons probably
resulted from both in situ microbial activity and chemical oxidation by the ozone. Hydro-
carbons could not be detected in the biostimulated section of the aquifer in water collected
1.5 years after treatment.
c. Soil Venting
Soil venting or air flooding can be used to supply oxygen for in situ biorestoration. Organic
vapors from the unsaturated zone are removed by increasing the flow of soil gases using
vapor recovery wells and air inlet wells.10" The volatile organic contaminants partition into
the soil gas and are transported to the vapor recovery wells. The increase in soil gas flow
in the unsaturated zone makes more oxygen available to reaerate the ground water.
Field tests have demonstrated that soil venting is effective in removing hydrocarbons from
the unsaturated zone. Following a gasoline spill in a porous and moderately permeable soil,
the concentration of vapors was reduced by 90% at a distance of 6.1 m and by 70% at 12.2
m from the vacuum source.1"" After reequilibration for 2 weeks, the average concentration
of the vapors was reduced to 389c of the pretest levels. Soil venting has also been used to
remove from 10 to 15 kg of trichloroethylene per day in another field trial."» A combination
of vacuum extraction and withdrawal and treatment was able to reduce the levels of carbon
tetrachloride by more than 99% in monitoring wells at a site contaminated by a storage tank
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Volume 18, Issue 1 (1988) 47
spill."' After operation for 30 months, the concentration of carbon tetrachloride was reduced
by 70% in the vadose zone. Levels of methane, acetone, and methylene chloride following
another tank spill were reduced below explosive limits within 1 week, but 6_weeks were
required to reduce the methylene chloride concentrations to drinking water standards.11: Soil
venting is restricted to volatile hydrocarbons in the unsaturated zone and. in some cases,
the capillary fringe.105 Formations with perched water tables or many types of contaminants
may not be amenable to treatment by soil venting."0
Wilson and Ward1" suggested that air flooding can be used to supply oxygen during in
situ biorestoration. Air contains 20 times more oxygen than water and is less viscous. For
a Fine sand or silt, about 32.000 pore volumes of water in comparison to 4000 volumes of
air is required to meet the oxygen demand for degradation of saturating concentrations of
hydrocarbons. Fewer volumes of each are required for more porous soils. In addition to
supplying oxygen, air flooding also removes vapors by physical weathering. In the absence
of a layer of pure product floating on the water table, the water table can be lowered by
withdrawing ground water to bring the contaminated region into the unsaturated zone for
treatment. However, lowering the water table would produce large quantities of contaminated
ground water that must be treated. Soil venting is currently being applied for in situ restoration
of gasoline-contaminated soil by supplying oxygen to a 30-m thick unsaturated zone where
the contaminants are held.7'
d. Collodial Gas Aphrons
Michelsen et ai.9' suggested that a colloidal dispersion of air contained in a surfactant
matrix could be used to supply oxygen for in situ bioreclamation. The microdispersion of
air, known as colloidal gas aphrons, is prepared by passing air or pure oxygen through a
venturi with a very small gas entry port into a surfactant solution or by use of a spinning
disk apparatus. The resulting colloidal material is basically a suspension of fine soap bubbles
with diameters of 25 to 50 nm that contain up to 65% gas. Up to about 55% of the pore
space in sands can be filled with the colloidal air dispersion. Coarse sand was better than
a fine sand in retaining the colloidal air. Laboratory tests indicate that the technique can
support the aerobic metabolism of phenol and hexadecane; better removal of hexadecane
was achieved when the suspension was prepared with oxygen (90%) rather than air (70%).
Methods for application of the colloidal air in the field are still in the developmental stages.
In addition, biodegradation of the surfactants used in the preparation of the colloidal gas
aphrons has also not been addressed.
3. Advantages and Disadvantages of Aerobic In Situ Biostimulation Processes
There are a number of advantages and disadvantages in using in situ biorestoration (Table
2). Compounds ranging from petroleum hydrocarbons to solvents have been treated by in
situ biorestoration (Table 3). Unlike many aquifer remediation techniques, in situ biorecla-
mation can often treat contaminants that are sorbed to soil or trapped in pore spaces. In
addition to treatment of the saturated zone, organics held in the unsaturated and capillary
zone can be treated when an infiltration gallery or soil flushing is used. Biodegradation in
the subsurface can be enhanced by increasing the concentration of dissolved oxygen through
the use of hydrogen peroxide, ozone, or a colloidal dispersion of air (colloidal gas aphrons).
Complete biodegradation (mineralization) of organic compounds usually produces carbon
dioxide, water, and an increase in cell mass. However, incomplete degradation (biotrans-
formation) of organic materials can produce byproducts that are more toxic than the parent
molecule. An example of biotransformation is the degradation of isopropanol to acetone at
a hazardous waste site described by Flathman and Githens.7'1 The levels of acetone increased
initially, but declined alter most of the isopropanol was removed. In situ biorestoration may
rely on the biodegradation potential of the indigenous subsurface microflora which usually
contains few pathogenic organisms unless the aquifer has been contaminated with waste-
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48 CRC Critical Reviews in Environmental Control
Table 2
ADVANTAGES AND DISADVANTAGES OF BIORESTORATION113"4
ACan be^sed to treat hydrocarbons and certain organic compounds, especially water-soluble pollutants and low
levels of other compounds thai would be difficult to remove by other methods
Environmentally sound because « does not usually generate waste products and typically results in complete
degradation of the contaminants
Utilizes the indigenous microflora and does not introduce potentially harmful organisms
Fast, safe, and generally economical
Treatment moves with the ground water
Good for short-term treatment of organic contaminated ground water
Disadvantages
Can be inhibited by heavy metals and some organics
Bacteria can plug the soil and reduce circulation
Introduction of nutrients could adversely affect nearby surface waten
Residues mav cause taste and odor problems
Labor and maintenance retirements may be high, equally for long-term treatment
Long-term effects ace unknown
May not work for aquifers with low permeab.l.ties that do not permit adequate circulation ol numems
waters 2 The time required to treat subsurface pollution using in situ biorestoration can often
be faster than withdrawal and treatment procedures. A gasoline spill in Ambler, Penn.; was
remediated in 18 months using in sin, biorestoration. whereas pump and treat techn.ques
were estimated to require 100 years to reduce the concentrations of gasoline to potable
levels,"-' In «« bto.ora.ion can also cos, less than o,her remedial op,ions. Flataan and
Githens™ es,ima,ed dm the cos, of in .in. biores.ora.ton would be one fifth of,ha, for
excwaUon and disposal of soil con.amina.ed wl,h isopropanol and tetrahydrofuran and ,n
addi,ion would provide an ul,ima,e disposal solution. The a«al »ne of ,re»,men, us,nS
hioreswration can be larger Ihan olher remedial .echnologtes because the treatment moves
wl[h the plume and can reach areas which would otherw.se be inaccessible
7fcw are also disadvantages io in siw biores,ora„on programs. Many organ,c compounds
in me subsurface are resist, .» b»r.» a,some sues.
rwSon in this instance would be ,o remove the inhitaory subs,ances and ,hen seed ,he
^bXTwi h app^autly adapted microorganisms; however. ,he benefts ,o adding
mtrXanisms totSe subsurface are s,ill undemonstrated. The formation and injection wells
m y dog from profuse microbial grow,!, which result irom the add.uon of oxygen and
Irien? n one bios,imula,ion project. microb,a] growth produced foaming in the well
S addi,ion. the hydrodynamics of the restorauon program must be properly
The nutrients added must be contained within the treatment zone because the
managed. untargeted areas can result in euuophication. High concentrations
T ^f lr«nde gSnd wa«r unpo,able. Metabolites of partial degrada,ion of organic
* ,™ flaTo^cnonableTas.es and odors. For example. ,he incomptae deg-
STn'of gasoline under low dissolved oxygen condi,ions resul.ed in phenol production;
nhPnoi was then degraded when more aerobic conditions were achieved.7- Biosumulation
Sets require continuous monitoring and maintenance for successful treatment: whether
these reouirements are greater than those for other remedial actions .s debatable. The process
results in increased microbial biomass that can exert an oxygen demand that can drive the
system anaerobic and result in the production of hydrogen sulfide or other objectionable
hvoroducts The long-term effects of biorestoration are unknown. In s,tu biorestoration is
difficult ,o implement in low-penneability aquifers in which perfusion of nutrients and oxygen
is slow or neglicible; however, many in .situ physical and chemical remediation processes
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Volume 18, Issue 1 (1988) 49
Table 3
CONTAMINANTS TREATED BY IN SITU BIOSTIMULATION
Contaminants
High "octane gasolin:
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Gasoline
Unleaded gasoline
Mineral oil hydrocarbons
Gasoline
Waste solvents and alkanes
Methyl chloride, n-bu-
tanol. dimethyl aniline,
acetone
Methylene chloride
Ethylene glycol
Isopropanol and
tetrahydrofuran
Aliphatic hydrocarbon
plasticizer
Chloroform
Treatment description Ref.
Air sparging with nitrogen and phos- 61—64
phonis addition
Air sparging with complete mix of 72
inorganics
Air sparging with addition of com- 78
plete inorganic nutrient solution
Air sparging and addition of nutrients 81
Dissolved oxygen supplied by an air 86. 99
stripper and sparging; nutrients also
added
Dissolved oxygen supplied by an air 87
stripper
Hydrogen peroxide plus nutrients 69
Initial treatment utilized air stripping; 87, 98. 99
hydrogen peroxide used later with
the nutrient formulation
Hydrogen peroxide supplied the 101
oxygen
Withdrawn water treated with ozone 108
and reinfiltrated
Soil venting used to supply oxygen to 71
unsaturated zone
Nutrients plus hydrogen peroxide 79, 87. 96, 100
Withdrawal and treatment by an acti- 27, 80
vated sludge process and recharge of
aerated nutrient-laden water
Withdrawal and treatment with air 75, 88
stripping followed later by treatment
in an activated sludge unit and
recharge
Treatment following withdrawal with 75, 89
ethylene-degrading bacteria and nu-
trients and then recharge
Treatment in an above-ground reactor 74
with addition of acclimated microbes
to the aquifer along with nutrients
Activated sludge and recharge of ac- 90
climated bacteria and nutrients
Activated sludge bioreactor with the 90
bacteria innoculated into the
subsurface
arc subject to the same restrictions. The success of in situ treatment schemes in low-
permeability aquifers depends on transporting the nutrients to the microflora or the active
agent to the contaminants. The process has been used in a variety of hydrogeological
formations (Table 4).
4. Related and Innovative Processes
There are a number of innovative, generally unproven. processes that potentially can be
applied to in situ biorestoration. These processes include land treatment, techniques thai
decrease the surface tension to enhance the mobility and improve the biodegradability of
the contaminants, application of enzymes, and treatment beds.
a. Land Treatment
Land treatment is a process in which the indigenous microflora in surface soils degrade
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50 CRC Critical Reviews in Environmental Control
Table 4
TYPES OF AQUIFERS WHERE IN SITU BIOSTIMULATION
HAS BEEN UTILIZED
Aquifer description
High permeability dolomite
Medium to coarse sand
Alluvial fan deposit of sand,
gravel, and cobbles with
some clay and silt
Poorly sorted mixture of
boulders, pebbles, cobbles,
sand. silt, and clay
Perched water (able in un-
stratified. unsorted layer of
clay, silts, sands, gravels,
and cobbles above a clay
layer
Tank vault filled with pea
gravel surrounded by sand
and sandy clay strata
Glacial outwash composed
of silt. sand, and gravel
Coarse sands and gravel
Shale and siltstone
Coarse sand with greater
than 5?r gravel
Glacial till composed of
sand, gravel, and boulders
in a silly clay matrix con-
nected to a fractured
sandstone
Shallow basin containing
sand and pea gravel
Flow characteristics
Pumping rate of 265—378 f/min
Pumping rate of 65—151 (/min
Flow of 2.4 m/day
Hydraulic conductivity of 9.4 x
10"*—1.7 x |0"' cm/sec
Pumping rate of 38—57 f/min
Flow rate in excess 100 nvyr;
pumping rate of 151 of the water-holding capacity
Optimal temperatures between 20 and 30"C
Optimal pH levels between 6 and 8
Availability of inorganic nutrients, principally nitrogen and phosphorus
the organic material contained in the soil. Loehr and Malina"5 suggested that land treatment
is useful for disposal of organic wastes from municipal sludge, petroleum, wood preserving,
leather tanning, coal gasification/liquefaction, food processing, and pulp and paper produc-
tion. Land treatment involves the addition of the organic waste to the soil, mixing to aerate
and incorporate the organics into the soil, and. if needed, adding fertilizer to stimulate
microbial activity. The process must be carefully managed to prevent overloading the as-
similative capacity of the soil and to prevent migration of the inorganic nutrients, organics.
and heavy metals.1"' Major factors that control biodegradation in land treatment are listed
in Table 5. Land treatment may be advantageous in comparison to other remedial techniques
because it requires minimal operation and maintenance and is a proven technology for some
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Volume 18, Issue 1 (1988) 51
wastes."8 However, the process may result in incomplete destruction of the organic wastes,
the soil mav be difficult to aerate effectively, the wastes must be contained within the
treatment zone, air pollution may result, and large areas of land are required. Land treatment
is usually limited to the upper 1.5 m of soil,"" which restricts its use in aquifer remediation.
However, land treatment may be used to treat excavated soil or wastes that are concentrated
at the water table of shallow aquifers. In a survey of treatment options for ground water
contaminated with gasoline, the Law Engineering Testing Company^" recommended that
land treatment be considered when a suitable site is available. In comparison to other
treatment technologies, land treatment was highly rated on the basis of effectiveness, capital
costs, reliability, and operability.1-'
Land treatment was used to treat a spill of 1.9 million t of kerosene.1:2 About 200 m'
of soil was excavated and the contaminated ground water was withdrawn and treated. The
contaminated soil was treated by adding lime and fertilizer (nitrogen, phosphorus, and
potassium in the ratio of 10:1:0.85) and frequently tilling the soil to a depth of 46 cm. The
fastest rate of kerosene degradation occurred during the warmer months of July and August.
The concentration of kerosene was reduced from 0.87% to innocuous levels in the upper
30 cm of soil during a 21-month period. However, kerosene persisted at a depth of 30 to
45 cm. perhaps a result of reduced aeration. Within the first 7 months, most of the n-alkanes
and unresolved hydrocarbons were degraded. A test for phytotoxicity after land treatment
indicated that the phytotoxicity of the kerosene had been reduced but not completely elim-
inated: crop yields were 20# below those in a control area 23 months after the spill.
b. Techniques That Reduce the Interfacial Tension
Insoluble organic compounds that are sorbed to soils can be mobilized and made more
available for microbial attack by decreasing the interfacial tension between the compounds
and water. The interfacial tension can be decreased with dispersants. surfactants, extractants.
and emulsifiers. Dispersants have been used in remediation programs to control marine oil
spills with some success.1--1 Addition of dispersants can increase the rate of reaction, but
may not increase the extent of hydrocarbon degradation. However, not all dispersants enhance
degradation of hydrocarbons and some may be toxic to microorganisms. Mulkins-Phillips
and Stewart'reported that only one of four dispersants stimulated biodegradation of crude
oil by marine bacteria: however, all four dispersants caused shifts in the microbial population.
The addition of surfactants to mobilize organics sorbed to soils has been tested in laboratory
studies. A combination of nonionic and ionic surfactants was most effective in removing
gasoline from sand columns by simple displacement and by draining the gasoline from the
capillary zone.Some of the surfactants identified in this study were biodegradable, whereas
others exhibited varying degrees of toxicity. Ellis et al. demonstrated that surfactants could
remove up to 95<7r of the crude oil and polychlorinated biphenyls trapped in sand columns,
whereas aqueous washes failed to remove appreciable quantities of these contaminants.
Surfactants may be used in combination with biorestoration to remediate aquifer contami-
nation problems. A surfactant wash can mobilize the residual hydrocarbon in the unsaturated
zone and render trapped hydrocarbon in the saturated zones more available for biodegra-
dation."3 A surfactant which is biodegradable and nontoxic is required. The application of
surfactants to subsurface contaminants may present additional environmental problems by
spreading contaminants to sections of the aquifer previously uncontaminated.
Emulsifers can be used to increase the surface area and render the oil more degradable.1:1
Emulsifiers can be either chemical additives or biological agents. Robichaux and Myrick1-*
reported that one chemical emulsifier increased the microbial decomposition of oil 18-fold:
however, other emulsifiers were less successful and many may have been toxic. Broderick
and Cooney12* reported that emulsifiers are produced by a variety of organisms in freshwater
environments, especially those associated with sediments. Laboratory studies conducted bv
Vanlooke et al.l,n showed that 10 to 20% of the oil adsorbed to soil was removed after the
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addition of a nutrient solution containing ammonium nitrate and peptone: microbial metab-
olites were thought to be responsible for the enhanced desorption. The ground water mi-
croflora in an aquifer contaminated with aviation fuel was reported to emulsify hydrocarbon
when supplied with dissolved oxygen, nitrogen, and phosphorus.111 Micelles and microe-
mulsions of the hydrocarbon are likely to be formed by bioemulsifiers which may facilitate
transport of the'hydrocarbon into the cell."2 Biosurfactant-producing bacteria may be used
to remediate contaminated aquifers but their use will be controlled by: (I) the physical and
chemical characteristics of the contaminant: (2) the geophysical and geochemical charac-
teristics of the formation such as pore size distribution and permeability, water quality, and
oxygen concentration; and (3) competition with indigenous microflora. The hydrocarbon
that is mobilized as a result of bioemulsification may be withdrawn from the aquifer and
treated by above-ground techniques."1 The microbial conversion of the hydrocarbons to
more polar compounds such as alcohols, ketones, phenols, or organic acids will also mobilize
the contaminants.
Another application of bioemulsifiers is enhanced oil recovery. Clark et al.1 4 found several
aerobic microbial species that could be used to bioemulsify oil in situ. Zajic and Akit'-"
found two bacterial strains that produced high concentrations of surfactants: one could remove
bitumen from tar sands when grown on hexadecane. A bacteria) culture supported on molasses
was able to release 19.5 to 48.7% and utilize 2 to 51% of the oil in a formation within 10
days.1"' Field trials were successful in two of seven reservoirs, increasing yields by 10 to
200%
Extraction techniques such as steam flooding, alcohol flooding, and thermal flooding also
may be used to mobilize organic contaminants in the subsurface; however, they have not
been demonstrated in the field."7 Horizontal or vertical-water sweeps can be used in perme-
able aquifers to reduce the quantity of hydrocarbons before treatment by other methods such
as in situ biorestoration.
c. Enzymes as an Innovative Treatment Technique
Another innovative in situ process is the addition of enzymes to degrade specific organic
compounds. In one investigation, a parathion hydrolase enyzme isolated from a mixed culture
of Pseudomonas was added to wet and dry plots of soil amended with the organic phosphorus
insecticide diazinon.15" In both wet and dry plots, removal was initially faster in the enzyme-
amended soil than in the control; however, diazinon levels in the test and control plots were
similar after 408 hr. The effectiveness of an enzyme depends upon its stability in the
environment and contact with the substrate. Adequate mixing to insure contact may be
difficult to achieve in an aquifer. In addition, enzymes may be better substrates for microbial
metabolism than many organic pollutants. The stability of an enzyme in the environment
may be adversely affected by changes in pH and solute concentrations.
d. Treatment Beds
Treatment beds are another innovative process currently under development. The process
consists of a trench which intercepts contaminated ground water and either a biological or
chemical treatment bed which removes the contaminants. Chemical treatment beds for or-
ganic compounds include activated carbon or synthetic resins."9 Biological treatment can
be accomplished using processes similar to trickling filters in which microorganisms colo-
nizing a surface are supplied with oxygen and nutrients, if necessary, and degrade the
contaminants which enter the treatment bed. Permeable treatment beds may plug or exhibit
channeling, which reduces their effectiveness. Similar results could be obtained without the
treatment bed by implementing in situ biorestoration in a narrow zone that intercepts and
contains the plume.
5. Potential for Anaerobic Processes
a. Anaerobic Degradation Pathways in the Subsurface
Anaerobic processes are important in the subsurface environment because oxygen may
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be depleted in contaminated aquifers as a result of aerobic microbial activity. However, low
levels of oxygen will support some microbial activity. Once the dissolved oxygen content
in ground water declines as a result of microbial activity, replacement depends-on recharge,
reaeration from soil gases, and mixture with oxygenated waters surrounding the organic
plume.140""
Degradation of a variety of compounds under anaerobic conditions has been demonstrated
to occur in aquifers and laboratory experiments using subsurface materials. However, an-
aerobiosis may retard the degradation of many compounds.47 The sequence of microbial
processes that occur as environmental conditions change from aerobic to anaerobic in the
subsurface usually follows the pattern of aerobic respiration, denitrification, manganese and
iron reduction, sulfate reduction, and finally methane formation.I4-141 Net energy production
decreases as the redox potential decreases.145 Bouwer and McCarty42144 demonstrated dif-
ferences in the degradation of organic compounds under different redox potentials: chlo-
roform and !. 1.1-trichloroethane were degraded by methanogenic. but not denitrifying,
bacteria. Ehrlich et al.:' l4ri reported the degradation of phenolics, but not polvnuclear ar-
omatics such as naphthalene, under methanogenic conditions. Recently Kuhn et al.-9 doc-
umented removal of tetrachloroethylene, the xylene isomers, and dichlorobenzene isomers
under denitrifying conditions. Wilson and Rees™ showed that degradation of benzene, ethyl-
benzene, toluene, and o-xylene occurred in methanogenic aquifer material from a landfill,
although the process was slow compared with aerobic pathways. The concentration of toluene
had been reduced by 879c after 6 weeks, however, more than 20% of the benzene, ethvl-
benzene, and o-xylene added to the microcosms persisted beyond 40 weeks. In the same
study, trichloroethylene and styrene degraded under anaerobic conditions, whereas chloro-
benzene persisted. Suflita and Gibson43 reported that 13 of 19 halogenated isomers of
benzoate, phenol, and phenoxyacetate persisted at concentrations >90% of that initially
added to subsurface materials collected from a sulfate-reducing zone; however, only 3.4-
dichlorobenzene remained at concentrations >5% of that originally added to methanogenic
samples collected downgradient of the sulfate-reducing zone. Maximal numbers of sulfate-
reducing and methanogenic bacteria are found at redox potentials of - 100 to - 150 and
-250 to -350 mV, respectively.146 Halogenated aliphatics such as trichloroethylene. tet-
rachloroethylene, carbon tetrachloride, and 1,1,1 -trichloroethane can be mineralized or de-
halogenated under reducing conditions147 to potentially more toxic compounds such as vinyl
chloride.148149 Tiedje et al.150 reported the anaerobic degradation of many other compounds
by organisms from a variety of environments.
b. Anaerobic Processes in In Situ Biostimulation
Anaerobic processes may be of potential use in in situ biorestoration processes. The redox
potential could be selectively adjusted to favor the degradation of a particular contaminant.
In addition to adjusting the redox potential, the pH of the ground water could be adjusted
to the neutral or alkaline conditions required for sulfate reduction, methanogenesis. and
usually denitrification. Anaerobic degradation of organic compounds would probably require
less inorganic nutrient supplementation because less energy, and therefore biomass, is pro-
duced."3 Batterman151 added nitrate to ground water contaminated with hydrocarbons in an
attempt to promote denitrification. The contaminated aquifer consisted of an 8- to 10-m
thick layer of sand which contained some silt and clay beds and a ground water flow of 4
m/day. The water was withdrawn from a deeper uncontaminated aquifer, aerated, passed
through a sand filter, and amended with nitrate at 300 mg/( before being recharged to the
shallow aquifer. Phosphate was not added because it was not limiting. The authors suggested
that anaerobic degradation accounted for the removal of 7.5 tons of hydrocarbon within a
period of 120 days. Removal of 1 mg of the hydrocarbon required 3.3 mg of nitrate.I5: The
concentration of aliphatics declined slowly from 1.5 to about 0.7 mg/<, whereas the con-
centration of total aromatics declined from 5.5 mg/( down to about 1.5 mg/< in approximately
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54 CRC Critical Reviews in Environmental Control
I year. The rate of decline in the concentration of xylene was much slower than that of
benzene and toluene. Water was injected during the test, which resulted in a rise in the level
of the hydrocarbons as well as the water table into the unsaturated zone. There was an
overall 40% reduction in the concentration of hydrocarbon as a result of the treatment process.
Insufficient information was provided to determine if anaerobic degradation was responsible
for the removal of the contaminants or if the removal was due to the oxygen introduced
when the injection water was aerated before it was recharged into the shallow aquifer.
Degradation of low concentrations of organic compounds under methanogenic conditions,
with acetate added at higher concentrations as a primary substrate, has been demonstrated.u:
McCarty'" proposed a scheme to treat contaminated ground water anaerobically using the
primary substrate concept. The system consists of an above-ground reactor to which substrate
and nutrients are added, a well casing bioreactor which operates anaerobically like a trickling
filter, and the aquifer. The above-ground reactor is used to develop an acclimated population.
The effluent from the above-ground reactor is injected into the well casing bioreactor to
introduce acclimated microbes into the aquifer or enhance adaptation of the indigenous
population to the contaminants. Once the acclimated population has developed, use of the
above-ground reactor can be discontinued.
A method that utilizes sequential aerobic and anaerobic conditions to degrade hazardous
wastes has been studied in soils and may be applicable to subsurface cleanup. An insecticide,
methoxychlor, was slightly degraded in soil under either aerobic or anaerobic conditions
after 3 months of incubation. When the samples were convened from an anaerobic to an
aerobic status, mineralization of the methoxychlor increased 10 to 70 times of that observed
in soils maintained aerobically throughout the incubation period.I,J The enhancement in
methoxychlor degradation in soils exposed to anaerobic and then aerobic conditions may be
a result of dechlorination of the insecticide under anaerobic conditions and degradation of
the dechlorinated products under aerobic conditions. This anaerobic-aerobic treatment scheme
may be useful in biorestoration of aquifers contaminated with halogenated compounds. The
aquifercouid be managed like a sequencing batch reactor in which an acclimated population
is exposed to deoxygenated water, then to aerobic conditions, and then the treated water is
withdrawn. The hydrauiicaily managed system is then allowed to sit idle until the next cycle
is initiated.
Rates of degradation under anaerobic conditions are typically slower than those under
aerobic conditions^ in addition, organic compounds may not be mineralized under anaerobic
conditions even after long periods of incubation.1" However, anaerobic treatment may be
required to degrade pollutants that are reclacitrant under aerobic conditions; also, anaerobic-
treatment may require less management. The application of anaerobic conditions to biores-
toration is still in the developmental stage and more research is required to demonstrate its
usefulness in the field.
C. Addition of Specialized Microbial Populations to tb« Subsurface
In addition to stimulating the indigenous microbial population to degrade organic com-
pounds, another innovative but not yet fully demonstrated technique is to add microorganisms
with specific metabolic capabilities to the subsurface.4 Specialized organisms may be in-
oculated into the subsurface environment or the environment may be altered to favor growth
of a population with specific metabolic capacities. Populations that are specialized in de-
grading target compounds are selected by enrichment culturing or genetic manipulation.
Enrichment culturing involves exposure of microorganisms to increasing concentrations of
a contaminant or mixture of contaminants. The type of microorganism that is selected, or
in essence acclimates to the contaminant, depends on the source of the inoculum, the
conditions used for the enrichment, and the substrate.1" Acclimation can result from an
increase in the number of organisms that can degrade the contaminant, new metabolic
capabilities that result from genetic changes, or an increase in the quantity of the enzymes
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necessary for the transformation.The genetic changes include overproduction of enzymes,
inactivation or alteration of regulatory gene control, or production of enzymes with altered
specificities.1,6
Genetic manipulation of microorganisms to produce specialized populations that cun de-
grade target contaminants is a relatively recent development. According to Kilbane.1" genetic
engineering may accelerate and focus the process of evolution. Genetic manipulation can
be accomplished by two different methods. In the first method, the organisms are exposed
to a mutagen such as UV light, nitrous oxide, or 8-azaquinonone, and then a population
with specialized degradative capabilities is isolated by enrichment culturing;15*•IW however,
this may produce weakened strains because the process is nonspecific and affects the entire
genome. In the second method, recombinant DNA technology is used to change the genetic
structure of the microorganism.'" The genetic structure is changed by inserting a DNA
fragment, often a plasmid that codes for a specific degradative pathway, into another or-
ganism. A plasmid is a piece of DNA that exists independently from the chromosomes of
the cell.,N1 The extra-chromosomal DNA can be transformed from one bacterium to another
by conjugation, transduction, or transformation. Multiple degradative capabilities can be
placed on a single plasmid that will allow the organism to degrade an array of compounds
or complete the degradation of a recalcitrant molecule. Genetic engineering can be used to
stabilize the degradative traits coded by the plasmid. increase the number of plasmids in a
cell, amplify enzyme production and activity, invoke multiple degradative traits, or produce
a novel degradative pathway."" In addition, organisms with different substrate affinities,
pH optima, or degradation rates can be fashioned.1"
I. Genetic Engineering to Enhance Degradative Activity
Genetic engineering has been used to enhance the degradation of the recalcitrant pesticide.
2,4,5-trichlorophenoxyacetic acid (2.4.5-T). Biodegradation of the pesticide is usually very
slow."" A mixed culture of microorganisms that uses 2.4,5-T as the sole carbon and energy
source was obtained by a technique called plasmid-assisted molecular breeding.The
technique involves inoculating a chemostat with microorganisms from a variety of hazardous
waste sites and organisms that carry an array of plasmids that code for degradation of specific
xenobiotics. A pure culture that could use 2,4,5-T as the sole carbon and energy source was
isolated from the mixed population and tentatively identified as Pscudomonas cepacia.'*'
In addition, the culture, designated P. cepacia AC 1100, was reported to oxidize many
chlorophenols. Degradation of both 2,4-dichlorophenoxyacetic acid (2.4-D) and 2.4.5-T was
expressed in another strain of P. cepacia after conjugal transfer of two plasmids from an
Alcaligenes entrophs sp. that degraded some chlorinated phenoxy herbicides.An inoculum
of 2 x I07 cells/g of P. cepacia AC 1100 degraded 95% of the 1000 mgH 2,4,5-T added
to soil at 25% moisture and incubated at 30"C.,bft Less 2,4.5-T was removed with a smaller
inoculum size and different temperatures and moisture contents. In addition, the 2.4.5-T-
degrading bacteria did not survive in soil without 2,4.5-T or when the concentration of the
compound had been depleted.165 Field trials to determine the effectiveness of the 2.4.5-T-
degrading bacteria have not been conducted.
Colaruotolo et al.167 received a patent for ''microbial degradation of obnoxious organic
wastes into innocuous materials." The process involves isolation of microbial cultures from
samples of soil and leachate from a hazardous waste site by enrichment culturing and then
application of the purified strains in the field to remove the contaminants. Microorganisms
capable of degrading selected isomers of chlorotoluene. dichlorotoluene. and dichloroben-
zoate were isolated. Conjugation and transformation experiments were conducted to transfer
the plasmid DNA, which conferred the ability to degrade some chloroaromatics. from the
original isolates to another organism. The patent claimed that the organisms could be used
to decontaminate soil, remove contaminants in the air. mineralize toxic organics in the
leachate from a chemical landfill, and thereby reduce the concentrations of noxious chemicals.
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Table 6
REASONS WHY INTRODUCED ORGANISMS FAIL TO FUNCTION IN THE
ENVIRONMENT'71
The concentration 0/ the compound is too low
The environment contains some substance or organisms that inhibit growth or activity, including predators
The inoculated organism uses some other organic other than the one it was selected to metabolize
The organic is nor accessible to the organism
2. Issues in Genetic Engineering of Microbes
Organisms that cannot easily exchange their genetic information with other organisms and
are restricted to growth under defined environmental conditions are preferred candidates for
genetic manipulation.161 Issues concerning the use of genetically engineered organisms in
the environment include (1) adverse effects on human health, (2) how to effectively monitor
their dispersal. (3) survival of the engineered organism in the environment. (4) regulation
of activity in nontarget areas; and (5) determination of set risk levels acceptable to the
public.lhK Many scientists argue that the engineered organism is not radically different from
that which is genetically unaltered. The release of genetically engineered organisms into the
environment is of great concern to some and some time may elapse before these organisms
are used.169 The survivability of genetically altered organisms in the environment is also of
concern. Surrogates of genetically engineered organisms which carried antibiotic resistance
were added to samples of sewage, lake water, and soil and survived at rates that varied with
the strain and environment tested.170 Some of the antibiotic-resistant strains reached steady-
state concentrations in lake water and sewage; however, all strains declined in the soil after
a period of 1 month. Pseudomonas strains that degrade 2,4-dichlorophenol and p-nitrophenol
were isolated from soil by enrichment-culturing techniques.171 The ability of the isolates to
degrade the phenol derivatives was variable when inoculated into lake water, sewage, and
soil.
Inoculation of a specialized microbial population into the environment may not produce
the desired results for many reasons (Table 6).171 The concentration of the target compound
required to support activity of a specific degrader may be limiting. Toxic or antimicrobial
substances such as antibiotics may be found in many environments. High-density inocula
may be grazed by predators and the degradative capacity severely decreased if the growth
rate of the introduced organisms is slow. In addition, adequate mixing to ensure contact of
the organism with the pollutant will be difficult to achieve in the subsurface.
Most hazardous waste sites involve contamination of the environment with more than one
compound. Therefore a mixture of organisms may be necessary to degrade all of the com-
pounds in the waste.127 Populations that have adapted to degrade many organic contaminants
may be isolated ftom biological treatment processes, such as sewage treatment, which recieve
pollutants. The efficacy of an inoculated population of specific degraders will depend on
environmental constraints such as temperature. pH. and the concentrations of substrate,
nutrients, and oxygen.i:7l7! Successful results from inoculation of foreign organisms are
more likely in simple environments because the environment can be controlled more easily.
An example of inoculation into a simple environment would be the introduction of bacteria
into a biological reactor, oil tanker ballast tanks, or fermentator; these also provide the
benefit of containing the microorganisms. To avoid problems encountered with inoculation
of foreign organisms into the environment, samples from the contaminated environment can
be collected, microorganisms that can degrade the pollutants can be cultured by enrichment
techniques or genetically engineered, and finally the specialized population can be reintro-
duced into the environment from which they came.111 In addition, genetic manipulation of
oligotrophic bacteria with high-atfinity enzyme systems may be advantageous because these
enzyme systems will allow the organism to attack low concentrations of organic pollutants."4
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3. Seeding Aqueous Environments with Microorganisms
Inoculants of specialized microorganisms have been used in treatment of contaminated
water. Atlas and Bartha'75 tested several commercial bacterial preparations and found that
the inocula were ineffective in treating oil spills in the marine environment. However, the
addition of fertilizer and a bacteria! seed isolated from an estuarine environment increased
petroleum degradation in a saline but not in a freshwater pond.176 After 6 weeks. 50<7c of
the oil remained in the saline pond. The lack of activity in the freshwater pond suggests
that the inoculum should be cultured from an environment similar to that being treated.
Colwell and Walker123 suggested that seeding would be unsuccessful in environments such
as the ocean; however, contained spills and lagoons may be amenable to such treatment.
Gutnick and Rosenberg177 stated that "there is no evidence to support the claim that "seeding'
oil slicks with microorganisms reduces oil pollution by stimulating petroleum biodegradation. "
4. Seeding Soil Environments with Microorganisms
The efficacy of inoculating soil with acclimated bacteria to remove selected contaminants
was tested in a series of experiments'78 using experimental chambers set up in greenhouses.
The contaminants, aniline and formaldehyde, were added to three types of soils (clay, sandy
loam, and organic-rich) and plants were seeded in the chambers. Removal of the contaminants
by a muxed microbial population from primary sewage effluent and an acclimated population
was investigated. Formaldehyde was not removed in organic soils amended with sewage
and acclimated bacteria: however, this treatment was successful in the upper and middle
zones of the sand and clay soils. Aniline was removed in the organic and sandy soils after
a second application of sewage microorganisms, nutrients, and yeast extract. Chemical
oxidation of the organics using hydrogen peroxide was effective in reducing aniline con-
centrations. None of the treatments were successful in removing aniline from the clay soil.
The removal of chlordane and 2,4-dinitrophenol by mutant-adapted microbial cultures was
also investigated. The inoculum was successful in degrading 2,4-dinitrophenol from the
upper layer of the clay soil only. The authors suggested that the sewage inoculum was a
low-cost, effective method for removal of aniline and formaldehyde in most soil types:
however, addition of the adapted population was not successful in these tests.
Inoculation of soils to remove chlorinated organics and pesticides has been attempted.
Daughton and Hsieh17* reported that inoculation of sterilized soils with a parathion-acclimated
culture reduced the concentration of the insecticide by 85%; however, the efficiency of the
inoculum in nonsterile soil was greatly reduced. Focht and Brunner""' used an Acinetobucter
strain as an inoculum to degrade bipheny! and polychlorinated biphenyls (PCBs) in soils.
The inoculum increased the initial and maximum mineralization rates and ihe disappearance
of the more heavily chlorinated biphenyls, but the overall extent of mineralization of PCBs
was not greater than that in uninoculated soil to which biphenyl had been added. The process
was thought to be a cometabolic-commensa! metabolism of the PCBs.
Remediation of soil contaminated with hydrocarbons by inoculating with hydrocarbon-
degrading organisms has been met with varying success. Schwendinger"" demonstrated that
inoculation of a hydrocarbon-degrading strain of Cellumonas in soil contaminated with
petroleum increased the rate of reclamation in comparison to soils amended with only
nutrients. Jobson et al.1"2 reported that the application of 10" cells of oil-degrading bacteria
per cubic centimeter of soil slightly increased the degradation ot the C.„- to C:,-group of
n-alkanes in comparison to soils amended with fertilizer only. However. Lehtomaki and
Niemela'"' reported that Brewer's yeast added to soils served primarily as a fertilizer rather
than as an inoculum to actively degrade the oil. Seeding boreal soil with an oil-degrading
inoculum increased microbial activity."*4 In laboratory studies, the addition of 300 ppm
nitrogen and 100 ppm phosphorus, inoculation, and adjusting the pH to 7 increased microbial
activity by at least a factor of four in comparison to unamended samples after 40 days of
incubation. An increase in plant growth in an oil-contaminated area in response to fertilizer
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addition was shown in field studies; however, the increased growth could have resulted from
the addition of fertilizer or enhanced removal of the petroleum. In contrast. Westlake et
al.IK:i reported no beneficial effects from the addition of oil-degrading bacteria to boreal
soils. The lack of enhancement may be a result of inadequate application of the inoculum.
The type of organisms isolated from enrichment culturing depends on conditions used during
the isolation procedure. For example, enrichments made at 4 and 20°C contained different
organisms, and cultures enriched on a low-quality crude were better adapted to utilize a
lower quality crude than cultures enriched on a high-quality crude.186 These data suggest
that enrichments for specialized populations should be conducted using the environmental
conditions and contaminants that are unique to the site under investigation.
An inoculum of pentachlorophenol-degrading organisms has been used to decontaminate
soil, river water, ground water, and other freshwaters.187 A Flavobacterium sp. that could
mineralize pentachlorophenol (PCP) was isolated from a man-made channel which was
exposed to the compound for several weeks.188 In addition to mineralizing PCP. the mi-
croorganism could attack a number of other chlorinated phenols but not all isomers."11' The
Flavobacterium sp. at a cell density of 106 cells/mf removed over 90% of the PCP added
to river water, ground water, and other fresh waters, usually within 48 hr.187 The organisms'
ability to degrade PCP was best between 15 and 35°C and at pH values between"?.5 and
9. Inoculum densities as low as 104 cells/mf resulted in efficient removal of PCP. The time
required to remove the PCP increased with increasing concentrations of PCP. When added
to uncontaminated soil, the PCP was rapidly mineralized."'8 The highest extent of miner-
alization occurred in soils with moisture contents between 15 to 20%.
Mineralization of PCP was observed at inoculum densities as low as 3.1 x I01 cells/g-
however, a slightly higher extent of mineralization was observed at a ceil density of 3 1 x
10" cells/g. Mineralization of PCP in one uninoculated soil began after 7 days of incubation
and mineralization proceeded to the same point as the sample inoculated with 107 cells'"
Concentrations of PCP in soil contaminated from a wood-treating landfill were reduced from
298 to 58 ppm after four applications of the inoculum in a period of 100 days. In another
contaminated soil, PCP levels were reduced from 321 to 41 ppm after one application of
seed, but similar levels of removal were observed in the uninoculated control. The seed
could not remove PCP from a third soil in which the concentration of PCP had been diluted
tenfold to 553 ppm and the pH adjusted to neutrality. Addition of 10" cells/g soil of a culture
of PCP-degrading Arthrobacter sp. reduced the half-life of PCP from 2 weeks to 15 hr
Edgehill and Finn"" reported that the rate of PCP disappearance was proportional to inoculum
size that ranged from 104 to 10" cells/g soil. Up to 85% of the PCP was removed within P
days in soil in which the seed had been thoroughly mixed; however, only 50% was removed
in the unmixed soil. Brown et al.l,j suggested that fixed film reactors with a PCP-adapted
population may be used to treat waters contaminated with PCP at concentrations below the
threshold of toxicity. A consortium that was attached to rocks from an artificial stream
amended with PCP was generally able to degrade PCP as fast as the Flavobacterium so
described by Crawford and Mohn.1"" A treatment system using two fixed film reactors in
series was then proposed; the first reactor would reduce high concentrations of PCP and the
second reactor would contain organisms that could remove PCP to low levels The co
was able to remove PCP to <1 |xg/f when the initial concentrations were
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Volume 18, Issue 1 (1988)
59
Table 7
SUMMARY OF AQUIFER REMEDIATION CASE
HISTORIES UTILIZING INTRODUCED ORGANISMS
Compound
Treatment description
Ref.
Formaldehyde
Acrylonitrile
Ethylene glycol and
propyl acetate
Dichlorobenzene.
dichloromethane. and
trichloroethane
Unidentified organic
compounds
Phenol and
chlorophenoi
Mutant bacteria added after con- 199
cemrations had been reduced by
air-stripping
Initial treatment by adsorption onto 199
GAC followed by inoculation
with mutant bacteria
Treatment above ground and later 200, 201
with specialized bacteria
Initial treatment with air stripping 200. 201
and then inoculation with a hy-
drocarbon-degrading bacteria
Hydrocarbon-degrading bacteria 202
added after levels reduced by
GAC and air stripping
Commercial degrader added to 203
above-ground treatment system
formed from rail ballast
contact between the specialized cells and the target contaminants. The cells may be filtered
out of the perfusing solution or sorbed onto soil before reaching the contaminants.u; In
addition, normal die-off may control the movement and spread of bacteria in well-sorted
sand, gravels, fractured rock, and karstic limestone.
Microbial movement through the subsurface depends on the characteristics of the soil and
microorganisms. Only 1% of an inoculum of a Pseudomonas strain passed through a 2-in.
sandstone core after washing with 123 pore volumes."3 Penetration of bacteria into sand-
stone cores with hydraulic conductivities >100 mD (hydraulic conductivity = 9.6 x 10"5
cm/sec) was rapid; however, penetration in cores with hydraulic conductivities below 100
mD was slow.1"" Motile bacteria moved three to eight times faster than nonmotile bacteria.
Hagedom'" summarized the results of selected studies on the maximum distance that mi-
croorganisms moved in various soils: 19.8 m in 27 weeks in a fine sand; 10.7 m in a sand
and sandy clay in 8 weeks; 24.4 m in a fine and coarse sand (time of travel not reported);
30.5 m in a sand and pea gravel aquifer in 35 hr; 0.6 to 4 m in a fine sandy loam (time of
travel not reported); 457.2 m in a coarse gravel aquifer in 15 days; 28.7 m in 24 to 30 hr
in a crystalline bedrock. Bacteria have moved as far as 920 m in the subsurface at rates of
up to 350 m/day .,9A Microbial movement through soil macropores is an important mechanism
of transport in all subsurface soils except sandy soils and those that are disturbed."7
Transport of microorganisms in the subsurface can occur. However, in situ biorestoration
programs using inoculation techniques will be affected by adverse conditions that decrease
the survival of microorganisms in the environment. Several factors must be considered before
an in situ biorestoration program utilizing acclimated bacteria is implemented. The source,
quantity, nature and biodegradability of the contaminants, and the environmental conditions,
of the site must be determined.|,,H In addition, laboratory tests to determine the kinetics of
degradation, the potential for inhibition under various conditions, requirements for oxygen
and nutrients, and the effects of temperature should be conducted. The formation must be
permeable enough to perfuse nutrients and the inoculum through the zone of contamination.
6. Aquifer Remediation Using Inoculation Techniques
Inoculation of microorganisms into the subsurface has been used in aquifer remediation
in conjunction with wastewater treatment processes. These cases are summarized in Table
7. A representative system is shown in Figure 3. In one case study. 26.500 ( of acrylonitrile
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60 CRC Critical Reviews in Environmental Control
^ DIRECTION OF GROUND WATER FLOW -|r
FIGL'RE 3. Combination of above-ground treatment with in situ biorestoration.
was spilled in a metropolitan area from a leaking rail car.,w The receiving aquifer contained
significant amounts of silt and clay and hence was rather impermeable. Initial treatment
involved withdrawal and treatment of the ground water by air stripping. After the concen-
tration of acrvlonitrile had declined to nontoxic levels, mutant bacteria were seeded into the
soil The concentration of aery lonitrile declined from 1000 ppm to nondetectable levels (limit
of detection 200 ppb) within 1 month; however, the role of the bacterial seed in acrvlonitrile
deeradation could not be determined.
Quince and Gardner00 documented the cleanup of 378.500 f of various organic com-
pounds including ethylene glycol and propyl acetate, over a 23.000-m- area. The soil
consisted of a thick silty clay that extended to a depth of more than 15.2 m: migration of
the oreanics into the main aquifer was prevented by the structure of the formation. Con-
tainment and recovery of the organics were limited to the perched water table located in the
upper clay layer. The contaminated ground water was withdrawn and treated by clarification,
aeration, and GAC. A biostimulation program with specialized bacteria, nutrients, and air
was initiated after the levels of the contaminants had decreased from 2000 to 10,000 ppm
to <200 ppm. During treatment, the concentration of ethylene glycol was reduced from
1200 to <50 mg/<. propyl acetate was reduced from 500 to <50 mg/(, and the total
concentration of spilled compounds declined from 36,000 to <100 mg/(. The resulting
concentrations of contaminants were acceptable to the regulatory agencies.
Quince and Gardner1*':<" documented the cleanup of a number of organic chemicals
including dichlorobenzene. methylene chloride, and trichloroethane that contaminated the
subsurface as a result of a spill from leaking tankers. The treatment scheme included recovery
of product with a vacuum system, soil flushing, air stripping, and then inoculation of
commercial hydrocarbon-degrading bacteria into an above-ground reactor followed by re-
charge of the effluent into the subsurface. A commercial microbial inoculum seeded into
the above-ground reactor significantly decreased the concentrations of the organic contam-
inants after 36 hr of exposure. The aeration was terminated after a 95% reduction in the
organic levels was achieved. The injected hydrocarbon degraders were expected to complete
the biodegradation in situ; however, the role of the added bacteria was not demonstrated.
An accidental spill of 492.000 I of organic chemicals entered a 4.6-m thick shallow
unconfined aquifer and resulted in total contaminant levels as high as 10.000 ppm.;u: A
drinking water aquifer was separated from the contaminated zone by 15.2 to 18..3 m of silty
clay The contaminated ground water was withdrawn and treated by clarification. GAC
adsorption, and air stripping. A program to enhance in situ biological degradation was
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Volume 18, Issue 1 (1988) 61
initiated after the concentration of the organics had declined from as high as 10.000 to 1000
ppm. The results of laboratory tests indicated that the indigenous bacteria could degrade the
contaminants when supplied with nutrients. Application of a commercial bacterial inoculum
did not increase the biodegradation rates of the organics; in fact, one compound (unidentified)
was degraded slower by the commercial hydrocarbon-degrading inoculum than the indigenous
population. Effluent from the treatment system was amended with hydrocarbon-degrading
bacteria, air, and nutrients and injected into the vadose zone. As a result, the concentrations
of the contaminants in one soil core were reduced from 800 to 150 mgIt in 2 months. In
another area, the concentration of the chemicals in composited soil samples declined from
24,000 to 2000 mg/(. The concentrations of the organics in the ground water were reduced
to <1 ppm. which met regulatory approval. Incorporation of biological treatment into the
restoration program decreased the cost of operation and maintenance. The role of the com-
merical inoculum in the removal of the contaminants could not be determined: in addition,
laboratory studies indicated that the inoculum did not enhance biodegradation.
A spill of 75.7001 of a 509c solution of formaldehyde from a railroad tank car contaminated
the soil and railroad bed in Ukiah, Calif.201 Contaminated surface and ground waters were
removed by a vacuum truck and 190 m1 of soil were excavated. Approximately 49 million
t of water was collected. The water was initially treated with hydrogen peroxide to reduce
the concentration of formaldehyde from 30,000—50,000 to 500—1000 ppm by oxidation.
The feasibility of in situ biological degradation of the remaining formaldehyde using a
commercial bacterial inoculum was then investigated. A commercial inoculum that contained
specially cultured microorganisms was chosen for the project. -The biological treatment
system consisted of a portable aeration tank, a spray system, and a trickling filter. The
ground water was heated to increase the destruction rate and the pH was adjusted as necessary
with sulfuric acid or soda ash: nitrogen and phosphorus were added as needed. The inoculum
was rehydrated with chlorine-free water and added to the system at a rate of 1.4 kg/day.
The concentration of formaldehyde in the treatment tank fell from >700 to about 10 mg <
after 24 days. The oxygen uptake rate in the sump ranged from 12 to 82 mg/l hr~1 and
from 29 to 51 mg/( hr~1 in the ballast gravel. The treatment program was temporarily
suspended for 1 day and the system was flushed. During this period, the concentration of
formaldehyde increased greatly; however, a rapid reduction in formaldehyde levels to < 1
mg/{ followed. The authors suggest that the removal of the formaldehyde was a result of
biological activity, however, they concede that proving the role of microorganisms in for-
maldehyde degradation would be difficult. In addition, the role of indigenous and inoculated
bacteria in formaldehyde degradation could not be separated.
7. Enrichment of Specific Populations
A strategy often used in industrial microbiology is to search through nature for an organism
with specialized metabolic capabilities and then culture that organism in a fermentor to
protect it from competition. However, this strategy would be difficult to apply in the sub-
surface environment because the specialized population must be competitive in addition to
performing the desired transformation. Enrichment culturing techniques are often used to
isolate organisms with specialized metabolic capabilities. The same concept can be used to
identify conditions that favor the colonization of that environment by organisms with special
traits.
The microbial utilization of pollutants as carbon and energy sources has already been
discussed. This section will emphasize the metabolism of pollutants by microorganisms
enriched on other primary substrates.
Oxygenated water-table aquifers are often polluted with chlorinated organic solvents such
as trichloroethylene.-'"The ubiquity of these compounds in oxygenated ground water
may result from their resistance to microbial attack under aerobic conditions in the subsurface.
However, more recent work has indicated that incubation of soils or aquifer material.", with
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CRC Critical Reviews in Environmental Control
methane, propane, or natural gas will enrich for microorganisms that co-oxidize trichloro-
ethylene and a variety of other halogenated organic compounds.3nA-313 This technique may
be applicable to in situ restoration of aquifers which are contaminated with chlorinated
organic solvents.
Using gaseous, aliphatic hydrocarbons as the feedstock for a forced co-oxidation is ad-
vantageous because they are nontoxic, relatively inexpensive, and widely available in the
form of natural gas, liquified petroleum gas. and propane. However, they do not support
anaerobic metabolism. In addition, if the gases are inadvertently supplied at concentrations
that result in the microbial depletion of the available oxygen, undesirable byproducts such
as foul-smelling organics, soluble iron, or hydrogen sulfide should not be produced The
disadvantage to enriching for specialized populations using gaseous aliphatic hydrocarbons
is the explosion hazard of the hydrocarbons mixed in air at unsafe concentrations One
constraint on in situ restoration programs is that the reagents must be dissolved in the perfusion
water to reach the zone of contamination; hydrocarbons and the oxygen required for their
metabolism are not very soluble in water.
Wilson and White3" developed a general relationship that may be used to predict the
extent of removal of a chlorinated organic as a function of the metabolism of a given amount
of hydrocarbon feedstock. The relationship is as follows
C/C„ = e-kh (2)
where C = the final concentration of the halogenated organic to be co-oxidized; C = the
initial concentration of the halogenated organic; h - the amount of hydrocarbon feedstock
to be consumed; and k = a utilization constant.
At present, there are limited data available to calculate utilization constants and the
generality of the relationship has not been widely tested. The equation may prove to be a
powerful tool in the engineering design of in situ biorestoration programs. Some utilization
constants for trichloroethylene exist.As a paper exercise, the extent of removal of tri-
chloroethylene at a number of critical engineering limitations, including the solubility of
methane, propane, and pure oxygen (24, 62. and 40 mg/f, respectively) and the oxvgen
content of well-oxygenated ground water (taken to be 8 mg/f) was estimated. Equation ">
was used to estimate the concentration of trichloroethylene that could be brought down to
5 ixgie, the maximum contaminant level proposed under the Safe Drinking Water Act
To preview the economics of in situ biorestoration, costs of the primary hydrocarbon feed-
stock were estimated at 25*/kg and the cost of oxygen supplied as hydrogen peroxide was
estimated at 400tf/kg oxygen supplied.
The predictions of trichloroethylene degradation by populations supported on gaseous
aliphatics using Equation 2 are illuminating (Table 8). At ambient oxygen concentrations
the reduction in the concentration of trichloroethylene supported on either propane or methane
is environmentally insignificant. The reductions supported by saturating concentrations of
oxygen will probably be useful but not sufficient to treat most contaminated water in one
cycle; the water will have to be circulated and reinjected with oxygen a number of times
or the oxygen will have to be supplied as hydrogen peroxide. Propane is about three times
more soluble in water than methane, and considerably greater removals of trichloroethylene
are possible using propane as the feedstock. Finally, the cost of trichloroethylene biores
toration in situ can probably be attributed to the cost of supplying the oxygen
The quantities of methane and propane are calculated from the equation of Wilson and
White.3" assuming utilization constants for trichloroethylene of 0.075 t water treated Der
milligram methane consumed and 0.10 { water treated per milligram propane consumed
and assuming utilization constants for cis- and trans-\ .2-dichloroethylene of 0 3 t water
treated per milligram methane consumed.
Vinyl chloride and vis- and froni-1.2-dichloroethylene commonly occur in ground water
contaminated with trichloroethylene and probably result from the reductive dechlorination
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Volume 18, Issue 1 (1988) 63
Table 8
ESTIMATED QUANTITIES OF OXYGEN AND METHANE
OR PROPANE REQUIRED TO BRING THE
CONCENTRATION OF TRICHLOROETHYLENE, cis- OR
trans- 1.2-DICHLOROETHYLENE OR VINYL CHLORIDE TO
5 |xg/*
Methane
Initial cone* required Propane required Oxygen required
DCE
Cents/
Cents/
Cents/
TCE
or VC
1000 gal
1000 gal
1000 gal
(|4g/<)
mg/<
(3785 I)
m fjl
(3785 0
mgU
(3785 I)
2.500
62
5.9
230
340
1.000
53
5.0
190
290
250
39
3.7
140
210
100
29
2.7
105
159
30
24
2.5
96
146
17
11
1.0
40
II
to
0.9
40
7
1 ->
0.2
8
5.8
2.0
0.2
8
5.0
0.0
6.700
24
2.5
96
146
1.000
18
1.7
71
107
100
10
0.9
40
9
2
0.2
8
5.0
0.0
0.0
TCE = irichloroeihylene: DCE = dichloroelhylene: VC = vinyl chloride.
of trichloroethylene.-14 Utilization constants for these compounds are not available. Wilson
and White2" estimated from the data of Fogel et al.201 that the constants are >0.3 (. water
treated per milligram methane consumed. Unpublished data of Henson;7: suggest that con-
stants for cis- and trans-1,2-dichloroethylene are >0.8 and 0.4 ( water treated per milligram
methane consumed, respectively. These higher utilization constants make aquifers contam-
inated with these compounds much better candidates for in situ biorestoration (Table 8).
Hydrogen peroxide will probably not be required to achieve adequate treatment. If the
contaminated water is pumped to the surface for treatment, the limited solubility of oxygen
becomes much less of a problem. The water can be exposed to any desired volume of air
in a fixed film bioreactor.3"
Table 9 summarizes the prospects for biorestoration of aquifers contaminated with specific
halogenated compounds. These data were compiled by comparing the relative rates of
degradation of these compounds in a variety of experimental systems to the rates of trans-
formation of trichloroethylene and cis- and trans-1,2-dichloroethylene, then assessing the
rates in light of the relationships portrayed in Table 8. Prospects are rated "good" if hydrogen
peroxide will not be required, 'j£air" if hydrogen peroxide is required, and "poor" if
environmentally insignificant removals cannot be attained with or without hydrogen peroxide.
The relationship of Wilson and White111 does not presuppose an upper limit on the
concentration of the chlorinated contaminant: however, an upper limit obviously exists and
toxicity effects have frustrated research in this area. Workers at both Stanford University
and R. S. Kerr Environmental Research Laboratory have isolated mixed microbial popu-
lations from nature that could degrade trichloroethylene. only to lose the ability to degrade
the compound when the primary alkane oxidizer was isolated in pure culture. It is tempting
to conclude that the trichloroethylene degrader is not an alkane oxidizer. However, other
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CRC Critical Reviews in Environmental Control
Table 9
PROSPECTS FOR TREATMENT OF THE COMMON HALOGENATED
ORGANIC CONTAMINANTS IN AQUIFERS THROUGH CO-
OXIDATION SUPPORTED ON GASEOUS ALKANES
Pump
Treat in the
Compound
and treat
aquifer
Ref.
Tetrachloroethylene (PCE)"
None
207, 209, 213
Trichloroethylene (TCE)
Good
Fair
206. 207, 209, 211, 213
c is-1,2-Dichloroethylene
Good
207, 209, 213
trans-1,2-Dichloroethylene
Good
207, 209. 213
Vinyl chloride
Good
207. 215
Direct utilization may be possible
1,1-Dichloroethylene
Fair
207
Carbon tetrachloride*
None
209. 213
Chloroform
Poor
208. 209, 213
Methylene chloride
Fair
75. 213
Direct utilization may be possible
1,1,1-Trichloroethane (TCA)
Poor lo
Poor
209, 211, 213
good
1.1,2-Trichloroethane (TCA)
Poor
209, 213
1,1-Dichloroethane (DCA)
Poor
209, 213
1,2-Dichloroethane
Poor
204. 209. 213. 216
Direct utilization may be possible
1,2-Dibromoethane (EDB)
Fair
209, 213
Direct utilization may be possible
¦ Removal of carbon tetrachloride and tetrachloroethylene seen in the soil exposed to natural gas is
probably an anaerobic process and not a direct result of aikane oxidation.
possibilities exist. In certain mixed cultures or microcosms of aquifers, trichloroethylene
started to inhibit oxidation of the hydrocarbon feedstock at a concentration of about 1000
270.271 -phjs js far below concentrations that produce toxicity in ordinary heterotrophs.
Perhaps the effective toxicant was trichloroethylene epoxide rather than trichloroethylene
itself, and the organism that oxidized the primary hydrocarbon feedstock was protected in
mixed populations by other organisms. This toxicity threshold must be more carefully defined
to aid in identifying contaminated ground water amenable to biorestoration. This work should
be done with mixed cultures or microcosms, using systems that simulate the conditions in
the subsurface environment.
No technique to remediate environmental contamination is universally applicable. How-
ever, there should be many contamination incidents where biorestoration through a forced
co-oxidation is the technology of choice, either alone or in conjunction with physical con-
tainment. Successful application of the approach will require adequate understanding of the
physiology of the biotransformation and quantitative information on the nutritional ecology
of the active organisms.
III. WITHDRAWAL AND TREATMENT
A. Biological Wastewater Treatment Processes
Ground water can be withdrawn and treated by conventional biological wastewater treat-
ment processes. Treatment processes used to treat contaminated ground water and leachate
from hazardous wastes include (1) suspended growth processes such as activated sludge,
lagoons, waste stabilization ponds, and fluidized bed reactors; and (2) fixed film processes
such as trickling filters, rotating biological discs, sequencing batch reactors, and others. The
wastewater can be treated on site by one of these processes or off site at a municipal or
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Volume 18, Issue 1 (1988) 65
commercial treatment plant. A short discussion of each process follows with regard to
hazardous waste management. More detailed discussions of these processes are presented
in J. R. B. Associates,"3 Ehrenfeld and Bass,'-" Shuckrow et al.,:n Nyer.:'8 and Canter
and Knox.2"
The most commonly used municipal wastewater treatment process, activated sludge, has
a number of advantages for treatment of contaminated ground waters. The units include an
aeration basin, a clarifier, and sludge recycle. Following treatment in the aeration basin, a
portion of the sludge collected in the clarifier is recycled. The recycling process allows an
acclimated microbial population to build up in the system, hence the name activated sludge.
The settled sludge can adsorb heavy metals and some organics which may cause the sludge
to be considered a hazardous waste.2" However, some compounds are removed by volatil-
ization during the aeration step.5-0 Activated sludge treatment can reduce the soluble bio-
chemical oxygen demand (BOD) to <10 mg/€ and the total BOD. including suspended
solids, to <30 mg/£. The retention time is short and consequently the process is sensitive
to toxic and hydraulic shocks. A survey of 92 industrial wastewater streams conducted by
the EPA reported mean BOD removal efficiencies of 86%.I3'' Specific organic compounds
can be degraded to low levels; effluent levels of phenol as low as 0.02 mg/{ have been
reported.2 ls
The sequencing batch reactor is an application of the activated sludge process which may
be used to treat hazardous waste leachates.221 The process involves five steps per cycle: (1)
fill — tfie wastewater is drawn into the vessel where some of the activated sludge from the
previous cycle remains; (2) react — aeration and mixing occur; (3) settle — clarification
occurs in-this step; (4) draw — the supernatant is withdrawn; and (5) idle — the system
remains idle until the next cycle is initiated. Treatment of hazardous waste with the se-
quencing batch reactor may be advantageous because the process is more complete and
flexible than other treatment technologies and can provide intermittent treatment: in addition,
the same tank can be used for both treatment and clarification. Up to 90% of the TOC from
a hazardous waste leachate was removed under a 24-hr cycle with a 10-day retention time.
Like activated sludge, surface impoundments such as aerobic lagoons, facultative lagoons,
anaerobic lagoons, and waste stabilization ponds rely on suspended microbial populations
to degrade organic material; unlike activated sludge, the biomass is not recycled.'39 222 Even
though the processes typically require less energy and supervision than activated sludge, the
operational controls are not as flexible.217 The retention time of waste in a surface impound-
ment is often on the order of weeks, whereas that of activated sludge may take a few hours.
In general, surface impoundments are quite large, and their size allows for dilution and
buffer fluctuations in organic load. Aerobic lagoons are aerated mechanically or by diffusion
to increase the degradation rate of organic material and mix the system.I3V 220 Organic material
is degraded aerobically at the surface and anaerobically near the bottom of facultative
lagoons.139 Because aeration is not forced or used, facultative and anaerobic lagoons offer
the advantage of easy operation and low cost; 317 however, anaerobic processes result in
incomplete degradation of organic compounds and hence low-quality effluent. Facultative
lagoons can also tolerate higher organic loading than aerobic lagoons and both facultative
and anaerobic lagoons may generate noxious odors.220 Anaerobic processes are enhanced in
anaerobic lagoons by low surface-to-volume ratios.'Waste stabilization ponds are lagoons
that are aerated by natural processes such as wind and photosynthesis. The ponds are
principally a polishing technique for low organic waste waters. The ponds are usually 0.3
to 0.6 m in depth. Removal efficiencies for surface impoundments are in the range of 60
to 90%. They are sensitive to shock loadings of toxic chemicals and fluctuations in temperature.
Fluidized bed reactors are filled with materials such as sand or coal that are suspended
by wastewater which flows upward through the material.The particles are colonized by
a dense growth of microorganisms which rapidly degrade organic material present in the
waste stream.
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66 CRC Critical Reviews in Environmental Control
In the fixed film process, wastewater is passed over a surface colonized with microor-
ganisms; (he attached biofilm degrades the organic material. The original fixed film process
the trickling filter, uses a solid medium such as rock or plastic as the surface for microbial
attachment.-" Trickling filters can remove from 60 to 859c of the BOD.::" Suspended or
colloidal organics-can be treated, and the process is usually limited to low organic loadings.
Trickling filters that are operated anaerobically are known as anaerobic filters."" The
anaerobic filter process can tolerate high loading rates. Low pH and inorganics such as
sodium, sulfate, and heavy metals may inhibit methanogenesis and toxic organics mav also
be a problem."4 The biological tower is another variation of the trickling filter. The tower
is packed with a colonizable surface which may reach a height of 4.9 to 6.1 m :i" The
process operates in a countercurrent mode; contaminated water is sprayed on the top of the
tower as air is pulled from the bottom.
A rotating biological disc is similar in concept to trickling filters. Discs or drums which
are coated with a biofilm are partially submerged and rotated through the wastewater
Rotation of the discs aerates the attached biofilm. The process is sensitive to shock load in"
and temperature fluctuations but otherwise is moderately reliable.1,3 In comparison to ac*
tivated sludge, rotating biological discs require less energy and are easier to operate, but
are similar in effectiveness."" Clarification may be required before and after treatment of
wastewater with rotating biological discs.IM
Biological wastewater treatment processes may be used to treat the followine classes of
organic compounds typically found in ground water alcohols, organic acids, aldehvdes.
ketones, quinones, amines, amides, carbohydrates, esters, some ethers, phenolics. and some
aromatics.-"0 "-1 Compounds that may be difficult to treat with biological wastewater proc-
esses include halocarbons. high molecular weight polynuclear aromatics, pesticides, and
organometals.1'"
B. Examples of Withdrawal and Biological Treatment
Biological wastewater treatment processes have been used in remedial action at several
hazardous and nonhazardous waste sites. Adequate treatment of Ieachates from recent mu-
nicipal refuse landfills that contained high levels of free fatty acids was achieved by biological
treatment.324 Leachates from older landfills may be more amenable to physical-chemical
treatment processes. In a pilot study. Stover and ^cannon-"5 were able to decontaminate
ground water from a hazardous waste site using activated sludge. The batch-activated sludge
pilot system was seeded with organisms that were acclimated to the same compounds found
in the contaminated ground water— phenols, cresols. dichlorobenzenes. and others. Fol-
lowing acclimation and stabilization of the batch-activated sludge for 3 weeks, the organisms
were able to reduce the total phenols, TOC, BOD, and COD by 809c or more within 24
hr.
C. Combinations of Biological Treatment with Other Processes
Combination of conventional biological wastewater treatment with other water treatment
processes such as GAC, air stripping, and addition of acclimated bacteria have also been
successful. Feasibility studies on decontamination of leachate from the Ott/Story hazardous
waste site in Muskegon, Mich., have combined activated sludge and GAC adsorption to
remove various halogenated aliphatics. benzene, and toluene."'' Initial attempts to acclimate
an activated sludge culture to the organic contaminants were minimally successful and the
addition of a commercial microbial culture was not effective; however, a combination of
GAC adsorption followed by activated sludge removed >95<7c of the TOC. The activated
sludge organisms removed the organics that were not sorbed in the GAC treatment. Treatment
efficiencies were >75% as long as the removal efficiency of the GAC was high. Anaerobic
treatment combined with GAC was less effective than aerobic treatment (activated sludee)
and suffered the same decline as the aerobic process when the GAC was saturated.: 17 Removal
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Volume 18, Issue 1 (1988) 67
of TOC by a treatment train using GAC followed by anaerobic and then aerobic biological
treatments was also tested."7 The biological treatment steps were not necessary when the
GAC sorption sites were not significantly saturated; however, the biological treatment in-
creased the removal efficiency of the treatment train as more GAC sorption sites became
saturated. The TOC removal efficiency of GAC combined with anaerobic and aerobic
treatment was less than that of GAC and aerobic treatment only.
Josephson67 reported that a combination of powdered activated carbon and activated sludge
was used to treat ground water contaminated with hydrocarbons, pesticides, and other
organics. A removal efficiency of 95 to 999c was achieved for the COD, total nitrogen, and
various organics.
Air stripping followed by biological treatment was used in a pilot study to treat ground
water contaminated with trichloroethylene. freon. 1,2-dichloroethene. toluene, ethyl ben-
zene, xylenes, vinyl chloride, acetone, isopropanol. o-dichlorobenzene. 1.1-dichloroethy-
lene. and 1,2-dichlorophenol."" Air stripping could remove all of the organics except tor
the nonvolatile compounds isopropanol and acetone; however, a treatability study indicated
that the nonvolatile compounds were biodegradable. Hence, a treatment system utilizing
both air stripping and biological treatment was recommended for this site.
Nyer and Sauer"" described the cleanup of shallow ground water from a Gulf Coast
hazardous waste site. The saline aquifer was contaminated with 400 mg/^ phenol and other
organics which resulted in a TOC concentration of 1300 mg/(. Several options that were
considered for treatment are reported with estimated costs per gallon in parenthesis: pond
evaporation with oxygen and nutrient addition ($0,028); deep well injection (SO. 183); so-
lidification/adsorption to concentrate the liquid and then adsorb the material to trench backfill
(SO.085); GAC adsorption (SO.058); biological treatment (SO.005).
A feasibility study indicated that the organics were biodegradable, but carbon adsorption
would be required as a polishing technique.-2'' The overall treatment system would consist
of: (1) pH adjustment; (2) chemical addition; (3) biological treatment with two aeration
basins, a clarifier, and a fixed activated sludge treatment system (FAST); (4) filtration through
a dual media filter; and (5) carbon adsorption. The FAST system uses panicles of plastic
colonized by bacteria in a well-mixed tank. The system is essentially a hybrid of activated
sludge and fixed film processes. The biological system was seeded with activated sludge
from a refinery that treated ballast from oil tankers. Results from the pilot plant, which
included the aeration plant and clarifier only, indicated that the TOC was reduced by 70%.
Addition of the FAST system, the dual media filter, and the carbon adsorption unit to the
treatment train reduced the concentration of TOC from 1300 to 18 mg/( (98%).:i*
Addition of mutant bacteria to a sequencing batch reactor, a process patented in 1985 by
Coiaruotolo et al.,"° was used to treat leachate collected from the Hyde Park Landfill in
Niagara Falls, N.Y."1 The leachate contained chlorinated organics. phenol, and benzoic
acid. A consortium of microorganisms that could degrade most of the contaminants was
isolated from the leachate; however, degradation of the pollutants by bacterial strains in the
consortium was variable.2" By genetic manipulation, organisms in the consortium that could
degrade the remaining compounds were found. Tests with bench-scale sequencing batch
reactors and also pilot-plant scale units indicated that the TOC was reduced by 85% or
greater and that individual contaminants were generally reduced by 95% or greater. The
biomass yield was 0.64 mg/mg feed TOC. Amendments of nitrogen and phosphorus did not
improve treatment over the addition of only nitrogen. Cost savings for the biological treatment
over the existing carbon adsorption system were estimated to range from 5538.000 up to
$783,000.
Bartha-13 suggested that inoculation of microorganisms into a wastewater treatment process
should be judged with caution. Inoculation may be useful for startup, disruptions, for certain
xenobiotics that cannot be degraded by the natural flora, or when the added organisms cannot
sustain themselves.
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68 CRC Critical Reviews in Environmental Control
IV. HYDROLOGIC CONSIDERATIONS AND MATHEMATICAL
MODELING OF BIORESTORATION
A. Hydrologic Considerations
A number of methods have been reported in the literature for the containment of contam-
inated ground water through hydraulic control or through injection-pumping networks of
wells. Biorestoration of a contaminant plume may involve the addition of nutrients such as
dissolved oxygen or hydrogen peroxide or the addition of microbes capable of degrading a
particular waste. In order for such additions to be successful, it may be necessary to use
hydraulic controls to minimize the migration of the plume during the in situ treatment process.
Thus, hydrologic considerations cannot be neglected in the biorestoration of aquifers.
Hydraulic control methods depend to a large extent on variability of aquifer hydraulic
conductivities, background velocities, and sustainable pumping rates. Typical patterns of
wells which are used to provide hydraulic controls include (1) the injection-production pair.
(2) a line of downgradient pumping wells. (3) a pattern of injection-production wells around
the boundary of a plume, and (4) the "double-cell" hydraulic containment presented by
Wilson.2-11 Well systems can also be used to capture and withdraw entire zones of contam-
inated water for treatment above ground.
Analytical equations and graphical solutions are available for estimating flow rates and
limits of hydrodynamic isolation under various boundary conditions. Numerical computer
models of ground water flow and contaminant transport are required when site geology is
complex, heterogeneous, and anisotropic. A simple hydrodynamic isolation system within
a uniform flow field involves the placement of a recharge well of the same strength upgradient
from a pumping well. Standard equations describe the head h(x,y) as a function of pumping
rate, ambient flow rate, and transmissivity of the aquifer. The region of recirculation which
connects the stagnation points can be evaluated and provides a measure of the capture zone
of contaminated ground water.:'4
Wilson"3 presents a "double-cell" hydraulic containment system which utilizes an inner
cell and an outer recirculation cell, with four wells along a line bisecting the plume in the
direction of flow. The method is more efficient in terms of flushing times and recirculation
rates than the single cell. The double-cell method provides added flexibility and a back-up
system if pumps should fail in either system.
Ozbilgin and Powers"5 described hydrodynamic isolation systems for several EPA haz-
ardous waste sites. Pumping wells and an upgradient recharge trench were successful in
retarding the advance of a contaminated plume at the site in Nashua. N.H. They concluded
that hydrodynamic isolation systems are generally less costly and time consuming than
physical containment structures such as slurry walls. Well systems are more flexible in that
pump rates and well locations can be altered as the system is operated over a period of time.
Shafer-1" indicated that pumping-injection systems can be used (1) to create stagnation
(no flow) zones at precise locations in a flow field, (2) to create gradient barriers to pollution
migration, (3) to control the trajectory of a contaminant plume, and (4) to intercept the
trajectory of a contaminant plume. However, the determination of pumping rates to achieve
a pollution control objective can be difficult. Thus, investigators have explored the application
of o^jmization theory to determine optimal pumping rates for creation of hydraulic controls.
Gorelick2-" and Atwood and Gorelick"* focus on using linear programming (LP) methods
to determine the best containment strategy in combination with a ground water flow simulator.
From a specified set of potential well sites, the model approach selects well locations and
optimal pumping/recharge rate schedules to contain the contaminant plume. Shafer"6 ad-
vocates the use of nonlinear programming combined with a ground water flow model and
an advective transport model. The optimization method is applied to examples for determining
stagnation points in a flow field and for steering the trajectory of a contaminant plume.
Optimization methods offer more efficient solutions than the typical trial and error approaches
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for exploring cleanup strategies. However, nonlinear programming requires the flow and
transport models to run during each iteration in which new pumping rates are selected and
tested in the overall performance index or objective function. In the present case, optimization
methods are complex and time consuming and may not offer any improvements over sim-
ulation for the-complex case of biorestoration alternatives.
Successful biorestoration alternatives at a particular site depend on the hydrological and
geological characteristics of the aquifer. If the contaminant plume is moving rapidly through
a sandy-gravelly zone, then hydraulic controls may be required to halt the advance of the
plume and to provide injection points for added nutrients or oxygen. Pumping out ground
water and surface nutrient additions prior to reinjection may provide a more controlled input
to the biorestoration process.
For the case of slowly moving organic plumes in a silty sand aquifer, it may be hydro-
logically difficult to pump or inject recharge waters at rates greater than 19 or 38 Omin. In
such cases, large numbers of wells may be needed to provide better "hydraulic spreading"
of treated recharge water. Simple lines of wells upgradient or downgradient of the plume
may not provide the required circulation, and wells within the plume are usually needed.
A five-spot pattern (one injection surrounded by four pumping wells) provides a useful
network for many cases.
In summary, hydraulic controls for the containment of ground water should be carefully
considered for any site where biorestoration is a viable treatment alternative. In particular,
injection-pumping well networks offer advantages for the creation of stagnation (no-flow)
zones or for the control of the trajectory of a contaminant plume. Once the plume has been
controlled hydraulically. then application of additional nutrients, oxygen, or microbes can
be better controlled and evaluated in terms of biodegradation efficiency.
B. Modeling Biorestoration
Mathematical modeling of biorestoration processes is useful in simulating cleanup progress
and can provide insights into the kinetics of the restoration process. Modeling of the hy-
draulics of the site may also aid in designing the optimum injection and production system.
Development of mathematical models of the biorestoration process requires: (l)a description
of the kinetics of biodegradation/transformation in the subsurface, (2) a description of the
abiotic processes controlling the transport and availability of the contaminant and other
required nutrients, and (3) an appropriate procedure for combining the processes and pre-
dicting the effect of the biorestoration technique. Most attempts at quantifying the transport
and removal of contaminants in ground water have relied on a solution of the classical form
of the advection-dispersion equation. The general form of this equation is
^ = V • (DVC - vC) + £R, (3)
at
where C * contaminant concentration, t = time, v = velocity vector, D = dispersion
tensor, R, = chemical and biological reaction terms, and V = the del operator.
Solutions to this equation have been obtained using a variety of analytical and numerical
methods. Thorou§| reviews of these methods may be found in Anderson.2"' Bear.2'"1 and
Javandel et al.-40 In this section, mathematical descriptions of biodegradation kinetics are
reviewed along with commonly used descriptions of abiotic transport processes. Commonly
used techniques for solving these equations are then reviewed as well as some of the
advantages and disadvantages of mathematical modeling.
C. Kinetics of Biodegradation
In situ biorestoration usually involves the addition of electron acceptors and nutrients to
enhance the growth of micoorganisms present in the subsurface and consequently increase
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70 CRC Critical Reviews in Environmental Control
the rate of contaminant biodegradation. In order to model the degradation process, rela-
, i are needed which describe the kinetics of microbial growth and consumption of
added nutrients and electron acceptors. These relationships are then combined with Equation
3 to describe the movement and consumption of the contaminant and added nutrients. One
of the most popujar relationships for describing the growth and decay of microorganisms
,nH ronsumotion of organic substrate was originally proposed by Monod:41 and modified
by Herbert et al.:" This model takes the following form:
f -"XYirh-bX <4>
and
dS
dt K + S (5)
X = microbial concentration (mg/<). m- « maximum specific utilization rate (1/day),
v - microbial vield coefficient (g/g). S = limiting substrate (mgIt), b « microbial decay
iWHvl and K = substrate half-saturation constant (mg/().
rate (!/aayj, ed be a hypcrbolic function of some limiting nutrient. Microbial decay
Growth is a independent of other environmental conditions. When several
compounds '1 used simutaneously. Equation 4 can be modified as
£ - idtc"."bx 161
u r = limiting nutrient i and K, » substrate half-saturation constant for nutrient i.
where C, ®uflction (c/K, + C,) goes to 1 and has no effect on the growth of the
When C, > Ki, the u c ^ t^e growth rate will be directly proportional to the
microorganisms, u w equations also predict that as the concentration of nutrient
concentration of nu ne. ^ ^ approach zero and eventually become negative. For a
i decreases, the ne g ^ |ong.term growth rate must be greater than or equal to zero;
population to s^l^entration 0f any limiting nutrient i may not fall below some minimum
(C ) where
v^min'
Kib
Cm,„ _ b <7)
that microorganisms may not be capable of degrading organic con-
This equation suggests {ration McCarty'M has suggested the addition of a second
taminants below this c0 the groWth of the organisms and allow degradation to below
nonharmful substrate to s ppu^ readjiv deeradable substrate could suppress the degradation
Cm,„. although addition o ^ Yoon et al.:4' have presented a mathematical model for
of the contaminant ot \ j obia| population on multiple substrates. For two substrates:
simulating growthofamixeflm.
^-^•YX-bX (8)
dt
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where S,, = substrates 1 and 2, K,, = half-saturation constants for substrates 1 and 2,
m*ii,m2 - maximum specific utilization rates for substrates 1 and 2. and a, , = inhibition
constants. This model can be further extended to describe growth on multiple substrates.
Some contaminants will not be used as a carbon and energy source by the microorganisms
but are transformed. Schmidt et al.34J have shown that transformation of these compounds
is proportional to microbial population and contaminant concentration (C) where
dC
—. = -KXC (9)
dt
Schmidt et al.344 used a logistic curve to describe the change in microbial concentration in
a batch system and developed a series of equations for describing change in contaminant
concentration with time for differing initial microbial and contaminant concentrations. Use
of the logistic curve greatly simplifies the mathematical computations but does not allow
simulation of the effects of changing aquifer parameters such as the addition of a second
substrate. In aquifer restoration, simulation of the microbial population using Equation 4
and change in contaminant concentration by Equation 9 may provide a more useful prediction.
Various workers have suggested that the kinetics of microbial growth, decay, and con-
sumption of organic contaminants in the subsurface are best described by models which
include terms for transport into attached biofilms or microcolonies. It is well known that
most microorganisms in the subsurface are attached to soil particles.10 This is thought to be
due to the competitive advantage attachment gives a microorganism at low substrate
concentrations.345
Workers at Stanford University have developed a series of models for simulating deg-
radation of organics in biofilms. The basic model assumes that degradation within the biofilm
can be described by Monod kinetics. Mass transport into the biofilm is by diffusion alone.
The diffusive flux (J) is calculated from Fick's second law
where Sf = concentration of rate-limiting substrate, z = coordinate orthogonal to bioftlm.
and D = diffusivity. Different diffusivities are assigned to the biofilm and an effective
diffusion layer adjacent to the biofilm. Williamson and McCarty34" originally developed this
model to simulate either substrate or oxygen limited biodegradation in wastewater treatment
biofilms. Rittman and Mccarty347 modified this approach to describe the steady-state biofilm
surrounding an injection well receiving tertiary-treated wastewater. Bouwer and McCarty34"
have further expanded the approach to allow simulation of secondary utilization of trace
organics while the biofilm is supported by an undifferentiated COD. Most recently. Kissel
et al.24*' have employed the biofilm concept to model carbonaceous oxidation, nitrification,
and denitrification within a mixed culture biofilm.
Much of the work on biofilms at Stanford occurred as an outgrowth of field studies on
organic degradation near an injection well. In this region, substrate fluxes and ground water
velocities will be high and a biofilm can be expected to develop. Actual biofilms are rare
in most aquifers and the majority of the microorganisms are present as microcolonies. Molz
et al.150 have recently modified the biofilm concept to describe the growth and decay of
microorganisms present in microcolonies. An average colony radius and thickness is used
to describe the microcolonies. Growth and Jecay within the colony is simulated by Monod
kinetics and includes both oxygen and substrate limitation. Transport to the microcolony is
limited by a diffusion layer at the colony surface.
D. Modeling Subsurface Transport
Keely et al.3" present a concise overview of evolving concepts of subsurface contaminant
transport. They argue that state-of-the-science methods may cost more at the outset but may
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yield overall benefits in the form of reduced cleanup costs compared with conventional
methods. The authors make the point that ground water processes are difficult to understand
and to model due to interactions which may not be simple to describe. Biotransformation
in the presence of dissolved oxygen in an aquifer represents an example where research
results may pavejhe way for reduced cleanup costs at many sites. If more detailed data can
be obtained about potential pathways and mechanisms of transport, the state of the art will
be advanced along with the potential for less costly site restoration.
The major physical processes of importance in ground water transport are advection and
dispersion.Advection is the transport of a contaminant by the bulk ground water flow.
Dispersion is the spreading of a contaminant front due to molecular diffusion and small-
scale variations in fluid velocity throughout the aquifer.
The major chemical processes of interest are adsorption, ion exchange, hydrolysis, and
oxidation-reduction reactions. Adsorption is "the process in which matter is extracted from
the solution phase and concentrated on the surface of the solid material.
/. Dispersion
Dispersion, the spreading of a contaminant front as it moves in the ground water, is an
area of particular controversy at this time. The dispersion process can be most easily described
as consisting of three components: (1) molecular diffusion resulting from Brownian motion
of individual molecules, (2) hydrodynamic dispersion resulting from variations in interstitial
pore velocities, and (3) macrodispersion resulting from structural variations in hydraulic
conductivity and, consequently, velocity. Differences in permeability between layers can
result in different ground water velocities and large variations in solute concentration. When
an aquifer is monitored using a fully screened well, ground water from different layers is
mixed, resulting in a smoothing of the apparent solute breakthrough curve. This smoothing
can result in very large apparent dispersion when matched against simple two-dimensional
solute transport models.
The effects of molecular diffusion, hydrodynamic dispersion, and macrodispersion are
frequently combined to form a dispersivity tensor which in some cases can be reduced to
three main components: longitudinal dispersivity (a,), transverse dispersivity (a,), and vertical
dispersivity (av).
Dispersion coefficients (D) used in the advection dispersion equation are found by
D « avm (11)
where v is the resultant velocity scalar and m is assumed equal to 1.
The physics and mathematics necessary to describe molecular diffusion and hydrodynamic
dispersion are well established. Bear234 and Fried'34 provide comprehensive experimental
and theoretical reviews of these processes. Tlte significance of the third component,
macrodispersion, is the subject of much debate. Anderson554 summarizes much of the current
research on the nature and significance of macrodispersion. At present, there appear to be
two dominant approaches:
1 Macrodispersion occurs due to random variations in permeability which can never be
adequately characterized; consequently, the only reasonable method is to employ a
stochastic procedure for describing the average movement of a solute.
2. The apparent spreading of many solute fronts is due to variations in permeability which
are complex but measureable; consequently, more effort should be expended towards
measuring the actual permeability distributions and using these as input for determin-
istic simulations.
No work has yet been focused on the effect of varying aquifer parameters on solute
transport as it relates to biorestoration. At present, the predictive accuracy of biorestoration
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modeling is severely limited by uncertainties in solute transport simulations. When simulating
the transport of a contaminant and oxygen or other nutrient, the most commonly used
numerical models will predict significant mixing between the contaminants and oxygen and
high rates of biodegradation. In real aquifers, contaminants may be trapped in a few areas
of low permeability while the oxygen or other nutrients are forced through the high-perme-
ability zones. In this situation, little mixing of the contaminants and oxygen will occur, and
consequently, little biodegradation. Until solute transport models are developed which can
adequately describe the complexities of subsurface flow, the accuracy in which biorestoration
can be simulated will be limited.
2. Chemical Processes
The major chemical processes which affect the transport of organic contaminants in ground
water are adsorption and hydrolysis.
Adsorption is a surface process in which a compound "sticks" to the solid aquifer material.
In the case of neutral, nonpolar organics, this stickiness is due to the much higher affinity
of the compound for other organics attached to the soil than for the polar water phase. In
the case of polar molecules, adsorption may be due to dipoie:dipole forces. The attraction
due to this mechanism is typically much weaker than that for hydrophobic compounds.
Naturally occurring organic material in aquifers is commonly present as a humic-kerogen
film over the clay particles. This organic material may originate from humic or fulvic acids
deposited with the original sediment or from infiltrating rain water. Organic material is
effectively preserved in tight clays where diffusion of oxygen is limited and the redox
potential is low.
Hydrolysis reactions can have a major impact on the mobility of organic compounds in
aquifers. These reactions are typically pH dependent and catalyzed by metal ions. The pH
of most solutions will approach equilibrium shortly after entering an aquifer. In this case,
hydrolysis reactions can be modeled as a simple first-order decay process.
When attempting to develop models for simulating the adsorption of contaminants in
ground water, many early investigators assumed that at low concentrations contaminants
move independently of other solutes, the reaction kinetics are fast relative to ground water
flow, and the natural reactants are uniformly distributed throughout the aquifer. These
assumptions allow the reactions to be analyzed using the equilibrium isotherm approach.
Under this approach, the variation in adsorbed contaminant concentration is described by
an adsorption isotherm:
S = f(C) (12)
where C = concentration of the contaminant in solution and S = concentration in the
nonmobile solid phase. This relationship can be incorporated into the advection dispersion
equation by considering the loss of solute to adsorption.
If S is a linear function of C, then the effect of adsorption can be replaced by a constant
retardation factor (R). In this special case, the adsorbed contaminant will move according
to Equation 2 with an effective velocity, v', where v' = v/R and an effective dispersion
coefficient, D' = D/R. A common method of calculating R is by the relation2"
R » I + p Kj/n (13)
where n is the aquifer porosity, p the bulk density, and Kd the partition coefficient in grams
of contaminant adsorbed per gram aquifer.
The use of a retardation factor depends on the following assumptions:
1. Adsorption can be described by a linear relationship between solute and solid phase
concentration.
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2. The reaction kinetics are fast relative to ground water flow.
3. Natural reactants attached to the aquifer material can be assumed uniformly distributed
in space.
4. Contaminant transport is independent of other liquid phase organics.
E. Mathematics? Models of Subsurface Biorestoration
Equation 3 with terms included for biodegradation can be solved to obtain the concentration
of the contaminant in space and time by both analytical and numerical methods. Analytical
solutions generally require less effort for the model user to employ, but may also require
simplification of the aquifer conditions and biodegradation processes. For uniform flow in
an aquifer in which biodegradation may be approximated as a first-order decay, solute
concentrations in space and time can be calculated using the one-dimensional solution of
Ogata and Banks-56 or the two-dimensional solution of Wilson and Miller.237 Approximating
biodegradation as a first-order decay would be appropriate when the microbial concentration
is constant, growth is only dependent on the contaminant concentration, and the contaminant
concentration is significantly less than the half-saturation constant (K). Simkins and
Alexander"* provide useful guidelines for determining when consumption of substrate may
be approximated as a first-order decay.
Numerical solution of Equation 3 allows the user much more flexibility in specifying
aquifer geometry and biodegradation kinetics. The most common mathematical formulations
for approximating the solute transport equation are finite differences, finite elements, and
the methods of characteristics.
Finite difference models have been developed for a variety of field situations including
saturated and unsaturated flow and for transient and constant pollutant sources. Finite dif-
ference methods operate by dividing space into rectilinear cells along the coordinate axes.
Homogeneous values within each cell are represented by values at a single node. Partial
differentials can then be approximated by finite differences and the resulting set of equations
solved by iteration.25' 360 Approximating the differentials by a difference requires that the
remaining terms of the Taylor's expansion be dropped, resulting in a truncation error and
significant spreading of the simulated contaminant front. This spreading has been termed
numerical dispersion and can often mask the actual physical dispersion process/"'
The finite element method also operates by breaking the flow field into elements, but in
this case the elements may vary in size and shape. In the case of a triangular element, the
geometry would be described by the three corner nodes where heads and concentrations are
computed. The head or concentration within an element is allowed to vary in proportion to
the distance to these nodes. Complex interpolating schemes are sometimes used to predict
accurately parameter values within an element and thereby reduce the truncation errors
common in finite difference procedures. Some numerical dispersion may still occur but is
usually much less significant. The use of variable size and shape elements also allows greater
flexibility in the analysis of moving boundary problems which occur when there is a moving
water table or when contaminant and flow transport must be analyzed as a coupled problem.
A disadvantage of the finite element method is the greater mathematical complexity and
generally higher computing costs.-*'-M
The method of characteristics (MOC) is most useful where solute transport is dominated
by convective transport. One of the most commonly used models employs a procedure where
idealized particles are tracked through the flow field.:w In step one. a particle and associated
mass of contaminant is translated a ceoain distance according to the flow velocity. The
second step adds on the effect of longitudinal and transverse dispersion and sources and
sinks for the contaminant.
All of these techniques can be used to simulate in situ biorestoration under certain cir-
cumstances, although no single procedure will be applicable to every situation. Only very
limited work has been done on simulating the simultaneous effects of advection, dispersion.
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Volume 18, Issue 1 (1988) 75
and chemical and biological processes. In the following section, the few studies that have
been performed are reviewed and the potential weakness of each technique discussed.
Kosson et al.3M employ a simple one-dimensional finite difference solution to simulate
the movement of hazardous industrial wastewaters through an acclimated soil column. Ad-
sorption is assumed to be linear and is described by a retardation factor. A portion of the
influent wastewater is assumed nondegradable. Biodegradation of the remainder is simulated
as a first-order decay. Experimental data are also provided by a field scale column used to
study the degradation process. The model adequately matches experimental data from the
later portion of the column biodegradation test when an acclimated microbial population
has developed. Agreement between model and experimental results was not as good during
the earlier part of the test before the microbial population had reached steady state.
Angelakis and Rolston2" present a mathematical model for simulating the movement of
insoluble (particulate) and soluble organic carbon through the unsaturated soil profile. Trans-
formation from insoluble to soluble and finally to carbon dioxide is assumed to follow first-
order kinetics. Transport of carbon dioxide is by gaseous diffusion. Simulation results are
obtained from analytical and numerical solutions. These results compare favorably with
experimental data from a series of column tests performed using primary wastewater effluent.
Insoluble and soluble organic carbon distributions were adequately matched. A variable
gaseous diffusion coefficient was required to match the observed carbon dioxide distribution.
Baehr and Corapcioglu266 present a one-dimensional model for simulating gasoline trans-
port in the unsaturated zone which includes transport by air, water, and free hydrocarbon
phases. The hydrocarbon is assumed to be composed of ' V components of differing
solubility and volatility. Exchange between the air, water, hydrocarbon, and adsorbed phases
is assumed to be rapid and described by equilibrium partition coefficients. Biodegradation
of the hydrocarbon is limited by the availability of oxygen which can enter the soil dissolved
in the water phase or by gaseous diffusion. Microorganism growth was not simulated directly
since biodegradation was assumed to be rapid relative to mass transport and to be limited
by the availability of oxygen. The equations are solved numerically using a finite difference
procedure. Model simulations indicated that the rate of biodegradation was very sensitive
to the diffusive properties of the soil. No experimental data are presented to test the model
predictions.
Sykes et al.267 simulate the anaerobic degradation of a landfill leachate plume in the
saturated zone at the Canadian Forces Base in Borden, Ontario. Microbial growth, decay,
and substrate utilization are simulated using Monod kinetics. When substrate concentrations
are significantly below the half-saturation constant and microbial populations are close to
steady state, the biodegradation kinetics are reduced to a first-order decay. The nonlinear
equations are generated using a Galerkin finite element approximation and solved using a
Newton Raphson iteration procedure. Model simulations indicate that the majority of the
degradable organics can be expected to be removed within a few meters of the landfill. This
finding was confirmed in field studies at the site. Sensitivity analyses performed using a
one-dimensional solution indicated that, under certain circumstances, pulses of organics
could escape from the landfill before a significant microbial population had developed.
Molz et al.250 present a numerical model for simulating substrate and oxygen transport
and use by attached microorganisms. The microbial population is assumed to be immobile
and present in microcolonies of an average thickness and radius. Transport into the micro-
colonies of oxygen and substrate is limited by diffusion through a stagnant layer adjacent
to the microcolony. Microbial growth and consumption of oxygen and substrate within the
microcolony is described by Monod kinetics. A one-dimensional solution is obtained nu-
merically using an Eulerian-Lagrangian finite element solution. The numerical model will
then be used to simulate the transport and biodegradation of substrate and oxygen in a
laboratory column. The simulation results indicate that degradation is most rapid near the
column inlet. The initial microbial population has a significant effect on the simulated
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breakthrough at the beginning of the simulation but has little effect on the steady-state
substrate distribution. Large substrate loadings at the column inlet quickly exceed the avail-
able oxygen supply, resulting in anaerobic conditions throughout the majority of the column.
Laboratory testing of the simulation model is planned.
Borden and Bedient140 present a numerical model of oxygen-limited biodegradation of
hydrocarbons in the saturated zone. Numerical solutions are obtained by approximating one-
dimensional flow as a series of completely mixed reactors and two-dimensional flow using
an explicit finite difference solution corrected for numerical dispersion. One-dimensional
model simulations indicate that biodegradation will be very rapid near the contaminant source
when oxygen is present. When no oxygen is present at the source, biodegradation will be
slow and limited by the transport of oxygen into the contaminant plume. Two-dimensional
simulations indicate that horizontal and vertical mixing are the major sources of oxygen to
the contaminant plume and control the biodegradation process. When adsorption of the
hydrocarbon to the aquifer is significant, advective fluxes of oxygen into the plume and
resulting biodegradation is also significant. Sensitivity analyses with the model suggest that
for many aquifers the reaction between oxygen and hydrocarbon may be approximated as
an instantaneous reaction since oxygen transport is rate limiting. Borden et al.IJ| employ
these results to modify the U.S.G.S. Solute Transport Model263 to simulate oxygen-limited
biodegradation of creosote wastes at a Superfund site. The model gave an adequate description
of the observed oxygen and hydrocarbon distributions in the shallow aquifer at the site and
was used to study various remedial actions, including no action and removal of the contam-
inant source.
Dawson et al.2"8 modify a petroleum reservoir code to simulate enhanced in situ biores-
toration using the equations presented by Borden and Bedient.140 Advective and dispersive
transport is calculated using a finite element-modified MOC solution which allows a large
time step and strongly advection-dominated flow. Because the rates of biodegradation can
be very high relative to transport, a time-splitting scheme is employed where the microbial
kinetic terms are solved separately using an implicit solution with a much smaller time step.
This model is then employed to simulate enhanced in situ biorestoration by the injection of
oxygen and production of contaminated water by a five-spot pattern. Simulations are per-
formed for a variety of conditions including uniform and random permeabilities and variable
adsorption.
F. Model Use and Limitations
The current technology for simulating subsurface biorestoration is still in its infancy. Some
progress has been made in developing kinetic descriptions of the biodegradation process and
combining these with available solute transport models. Unfortunately, little reliable field
data have been available to rigorously test these models. Considerable uncertainty exists
over the importance of simulating transport into biofilms or microcolonies. Also, the effects
of variations in aquifer parameters on the efficiency of biorestoration are unknown. At
present, the technology is not available to quantitatively predict the efficiency of enhanced
biorestoration, but significant advances are being made in our ability to describe the process.
V. CONCLUSIONS
Of the available biological aquifer remediation techniques, the most effective demonstrated
methods are enhancement of the native population and withdrawal and treatment by various
wastewater treatment processes.2"" Before any aquifer remediation technique can be imple-
mented. a thorough understanding of the hydrogeology and contamination problems of the
site must be obtained and used to design the treatment system,4 When successful, costs for
in situ biorestoration are generally less than physical or chemical remediation techniques.
/n situ biorestoration compares favorably with other common remedial actions such as
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Volume 18, Issue 1 (1988) 77
excavation and withdrawal and treatment by carbon adsorption or air stripping.*7 Excavation
is generally limited to surface soils above the water table and can be restricted by the physical
construction on the site. Excavated soils must be transported to a secure landfill with the
potential for liability from an accident during transport or a leak from the receiving landfill.
The contaminated ground water must be withdrawn before air stripping and carbon adsorp-
tion. The ability to withdraw organic contaminants is a function of the solubility of contam-
inants and the permeability of the soil. Highly soluble organics in high-permeability soils
can be effectively withdrawn. Compounds which are hydrophobic can be effectively treated
with carbon adsorption, but because of their hydrophobicity are also more likely to be
adsorbed to the soil and not removed by withdrawal systems. Carbon adsorption generates
spent carbon that must be treated or sent to proper disposal facilities. Air stripping is effective
for compounds with high volatilities, but not those with high boiling points or high solu-
bilities. Air stripping simply transfers the contaminants to another phase of the environment
unless expensive carbon adsorption or incineration is used to treat the off gases.
Addition of oxygen, nitrogen, phosphorus, and trace minerals stimulates the acclimated
indigenous microbial population to aerobically degrade many subsurface contaminants. In
situ biorestoration has been chiefly used to treat gasoline-contaminated aquifers, but also
has been employed with ethylene glycol and solvents including acetone, tetrahydrofuran,
methylene chloride, n-butanol. dimethyl aniline, and isopropanol. Biorestoration effective-
ness will be affected by toxic levels of organics and heavy metals. In general, in situ
bioreclamation has been effective in reducing the quantity of the contaminants but not in
completely eliminating them. The treatment moves with the plume, allowing treatment of
trapped or sorbed contaminants, or by using soil flushing or an infiltration gallery, in situ
microbial treatment can reach areas that are not accessible by other techniques. Biorestoration
has been used in a number of aquifers, but may be of limited usefulness in those with low
permeabilities. Undesirable metabolic and inorganic nutrients may escape from the treatment
zone and affect ground water or surface water quality. Alternative oxygen sources such as
ozone, hydrogen peroxide, pure oxygen, and air flooding or soil venting may speed the
removal of the organic contaminants, but their impact on the microbial population and the
geochemistry of the site is not fully understood. Innovative processes such as treatment beds
or land treatment can be used in some situations. In the presence of an acclimated microbial
population, many aquifers will be anaerobic because the microorganisms will have depleted
the dissolved oxygen. It will be possible to use anaerobic degradation to remove contami-
nants. although the technology for this treatment has not yet been developed. Reducing the
interfacial tension between the hydrocarbon and ground water with surfactants, dispersants.
or emulsifiers will mobilize the contaminants and may make them available for microbial
degradation. Combinations of in situ biorestoration treatment with other chemical, physical,
or biological treatment processes have been successfully utilized in aquifer remediation.
Treatment at the surface by biological wastewater processes is a proven technology. The
biological processes include activated sludge, lagoons, waste stabilization ponds, fluidized
bed reactors, trickling filters, rotating biological discs, and sequencing batch reactors. All
of these processes are dependent upon extraction of the contaminated ground water from
the subsurface. Combinations of conventional wastewater treatment processes and other
water treatment processes have also been successful.
Alteration of the subsurface microbial community has a great deal of potential to allow
degradation of recalcitrant compounds in the subsurface. The organisms are selected by
enrichment culturing or genetic manipulation. However, introduction of non-native micro-
organisms may be limited by movement of the organisms through the subsurface, survival
of the organisms, and accessibility of the organic contaminants. Addition of an acclimated
population may be more successful when combined with wastewater treatment processes
where the environment can be more closely regulated. Although the aquifer remedial actions
that have used a microbial seed have not conclusively shown that the added organisms were
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78 CRC Critical Reviews in Environmental Control
responsible for removal of the contaminant, the concentrations of the contaminants were
reduced. Alteration of the environment to promote the activity of a particular component of
the microbial community is another promising technology. Field tests and further research
are currently underway for this technology. The environment is altered to promote the growth
of organisms that co-oxidize halogenated aliphatics when supported on gaseous hydrocarbons
such as methane, propane, or natural gas.
Techniques for simulating the subsurface biorestoration process are under development,
but little reliable field data have been generated that can be applied to these models. Some
of the major considerations in simulating transport and biodegradation of organic contam-
inants in the subsurface are poorly understood; these include the importance of transport of
organics to the bacteria and the variability in aquifer parameters.
ACKNOWLEDGMENT
Although the research described in this article has been supported by the U.S. Environ-
mental Protection Agency through Assistance Agreement No. CR-812808 to Rice University,
it has not been subjected to Agency review and therefore does not necessarily reflect the
views of the Agency and no official endorsement should be inferred.
REFERENCES
1. Bitton, G. and Gerba, C. P.. Groundwater pollution microbiology: ihe emerging issue, in Groundwater
Pollution Microbiology, Billon. G. and Gerba. C. P.. Eds., John Wiley & Sons. New York. 19X4. I
2. Keswick. B. H„ Sources of groundwater pollution, in Ground Water Qualm. Ward. C. H.. Giger. W..
and McCarty. P. L.. Eds.. John Wiley & Sons. New York. 1984. 39.
3. Craun. G. F., Health aspects of groundwater pollution, in Groundwater Pollution Microbiolovx. Bmon.
G. and Gerba. C. P.. Eds.. John Wiley & Sons. New York. I9K4. 135.
4. Lee, M. D. and Ward. C. H.. Ground Water Restoration, repon submitted to th<: J AC A Corporation.
Fori Washington. Penn.. 1986
5. Dunlap. W. J. and Mc.Nabb. J. F„ Subsurface Bioloitical Acuvm in Relation to Ground Water Pollution,
EPA-660/2-73-014. U.S. Environmental Protection Agency. Ada. Okla.. 1973. 60,
6. Leenheer, J. A., Malcolm, R. L., McKlnley, P. W., and Ecles. L. A., Occurrence of dissolved organic
carbon in selected ground-water samples in Ihe United States. J. Res. U.S. Geo!, Surv.. 2. 361, 1974.
7. Waksman. S. A., Bacterial numbers in soils, at different depths, and in different seasons of the year. Soil
Sci., I, 363. 1916.
8. Dunlap. W. J.. McNabb, J. F.. Scalf, M. R„ and Cosby, R. L., Sampling for Organic Chemicals and
Microorganisms in the Subsurface, EPA-600/2-77-176, U.S. Environmental Protection Agency. Ada. Okla..
1977.
9. Wilson, J. T., McNabb. J. F.. Balkwiil. D. L„ and Ghiorse. W. C„ Enumeration and characterization
of bacteria indigenous to a shallow water-table aquifer. Ground Water. 21. 134. 1983.
10. Harvey, R. W„ Smith, R. L.. and George, L„ Effect of organic contaminants upon microbial distribution
and heterotrophic uptake in aCapeCod. Massachusetts aquifer, Appl. Environ. Microbiol.. 48. 1197. 1984
11. Ghiorse, W. C. and Balkwiil, D. L., Microbial characterization of subsurface environments, in Ground
Water Quality, Ward, C. H.. Giger, W., and McCarty, P. L., Eds., John Wiley & Sons, New York, 1985,
387.
12. Ghiorse. W. C. and Balkwiil, D. L., Enumeration and morphological characterization of bacteria indig-
enous to subsurface environments. Dev. Ind. Microbiol., 24, 213, 1983.
13. Smith. G. A., Nickels, J. S„ Kerger. B-JRU Davit. J. D., Collins, S. P., Wilson. J. T.. McNabb.
J. F., and While. D. C„ Quantitative characterization of microbial biomass and community structure in
subsurface material: a procaryotic consortium responsive to organic contamination. Cati. J. Microbiol.. 32.
104. 1986.
14. Stetzenbach. L. D., Kelly, L. M., and Sinclair, N. A.. Isolation, identification, and growth of well water
bacteria. Ground Water. 24, 6. 1986.
-------
Volume 18, Issue 1 (1988) 79
15. Smith, G. A., Nickels. J. S„ Davis, J. D., Findlav, R. H., Yashio, P. S.. Wilson. J. T.. and White.
D. C., Indices identifying subsurface microbial communities that adapted to organic pollution, in Proc
2nd Int. Conf, on Ground Water Quality Res., Durham. N. N. and Redelfs. A. E.. Eds.. Oklahoma Stale
University Printing Services. Stillwater. Okla.. 1985. 210.
16. Balkwill, D. L. and Ghiorse, W. C.. Characterization of subsurface bacteria associated with two shallow
aquifers in Oklahoma. Appl. Environ. Microbiol., 50. 580. 1985.
17. Bone. T. L.and Balkwill. D. L., Improved flotation technique lor microscopy of in situ soil and sediment
microscopy. Appl. Environ. Microbiol., 51. 462. 1986.
18. Webster, J. J.. Hampton. G. J., Wilson. J. T.. Ghiorse, W. C., and Leach, F. R., Determination of
microbial cell numbers in subsurface samples. Ground Water. 23. 17. 1985.
19. White, D. C.. Smith. G. A., Gehron. M. J., Parker. J. H.. Findlav, R. H.. Martz. R. F.. and
Fredrickson, H. L., The ground water aquifer microbiotia: biomass. community structure, and nutritional
status. Dev. Ind. Microbiol., 24, 204. 1983.
20. Hoos, E. and Schweisfurth. R.. Investigations about the distribution of bacteria between 10 and 90 meters
below soil surface, in Jarhbucgh vont Wasser. Verlage Chemie. Weinheim Bergstrasse. 1982.
21. Ehrllch, G. G., Godsy, E. M., Goerlitz, D. F., and Hult. M. F.. Microbial ecology of a crensoie-
contaminated aquifer at St. Louis Park. Minnesota. Dev Ind. Microbiol.. 24, 235. 1983,
22. Federle. T. W., Dobbins, D. C., Thornton-Manning, J. R., and Jones. D. D.. Microbial biomass.
activity, and community structure in subsurface soils. Ground Water. 24, 365. 1986.
23. Towler. P. A., Blakey, N. C., Irving, T. E., Marls. P. J. K., Baxter, K. M.. and NtacDonald.
R. M.. A study of the bacteria of the chalk aquifer and the effect of landfill contamination at a site in
Eastern England, in Hydrngeology in the Service of Man. Vol. XVIII Part 3. Groundwater Quality Man-
agement. Memories of the IHth Congress of the International Association of Hydrogeologists. International
Association of Hydrological Sciences. Cambridge. 1985. 84,
24. Betoin, R-. Sinclair, j. L.. Balkwill, D. L., and Ghiorse, W. C., Variations in microbial populations
and activities in vertical profile from surface soil to bedrock at Lula. Oklahoma. Am. Hoc. Microbiol.
Abstr., N-82, 255. 1986.
25. Hirsch, P. and Rades-Rohkohl, E., Microbial diversity in a groundwater aquifer in northern Germany.
Dev. Ind. Microbial.. 24, 183. 1983.
26. Larson. R. J. and Ventulto, R. M., Biodegradation potential of ground-water bacteria, in Proc. 3rd Xutl.
Symp. on Aquifer Restoration and Ground Water Monitoring, Columbus. Ohio, May 1983. 402.
27. Jhaveri. V. and Mazzacca. A. J., Bio-reclamation of ground and groundwater. A case history, in Proc.
4th Natl. Conf. on Management of Uncontrolled Hazardous Waste Sites, Washington. DC,. October 198?.
242.
28. Novak, J. T„ Goldsmith, C. D., Benoitt, R. E., and O'Brien, J. H., Biodegradation of alcohol-, in
subsurface systems, in Semin. Progr. Degradation, Retention and Dispersion of Pollutants in Groundwater.
Copenhagen. Denmark. September 1984, 61.
29. Kuhn, E. P., Colberg, P. J., Schnoor, J, L„ Warner, O., Zehnder, A. J. B.. and Schwarzenbach.
R. P., Microbial transformation of substituted benzenes during infiltration of river water to ground w ater
laboratory column studies. Environ. Sci. Techno!.. 19, 961. 1985.
30. Suftita, J. M. and Miller, G. D., Microbial metabolism of chlorophenolic compounds in ground water
aquifers. Environ. Toxicol. Chem., 4. 751. 1985.
31. Wilson. J. T.. McNabb, J. F., Cochran, J. W., Wang, T. H., Tomson. M. B.. and Bedient. P. B.,
Influence of microbial adaptation on the fate of organic pollutants in ground water, Em iron. TomcoI. Chan..
4. 721. 1985.
32. Lee, M. D. and Ward, C. H., Microbial ecology of a hazardous waste disposal sue: enhancement of
biodegradation. in Proc. 2nd Int. Conf. on Groundwater Res. Qua/in Res.. Durham. N.N. and Rcdelts.
A. E.. Eds.. Oklahoma State University Printing Services. Stillwater. Okla.. 1985. 25.
33. Barker. J. F. and Patrick, G. C., Natural attenuation of aromatic hydro-carbons in a shallow sand aquifer,
in Proc. NWWAIAPI Conf. on Petroleum Hydrocarbon and Organic Chemicals in Ground W'afcv — Pre-
vention, Detection, and Restoration. National Water Well Association. Worthington. Ohio. 1986. 160
34. White, K. D„ Novak, J. T„ Goldsmith, C. D., and Beven. S„ Microbial degradation kinetics of alcohols
in subsurface systems, in Proc. NWWAIAPI Conf. Petroleum Hydrocarbons and Organic Chemicals in
Ground Water — Prevention. Detection, and Restoration, National Water Well Association. Worthington.
Ohio. 1986.
35. Spain, J. C. and van Veld, P. A„ Adaptation of natural microbial communities to degradation of xenobmnc
compounds: effects of concentration, exposure time, inoculum, and chemical structure. Appl. Environ
Microbiol.. 45. 428, 1983
36. Alexander, M.. Environmental and microbiological problems arising front recalcitrant molecules. Mnrnh
Ecol.. 2. 17, 1975.
37. Alexander. M„ Biodegradation of chemicals of environmental concern. iYu-m r, 211. 132. 1980
-------
80 CRC Critical Reviews in Environmental Control
38. Wilson, B. H. and Rees. J. F., Biotransformation of gasoline hydrocarbons in methanogenie aquifer
material, in Proc. NWWA/APl Conf. on Petroleum Hydrocarbons and Organic Chemicals i„ Ground wJJr
-Prevention. Detection, and Restoration. National Water Weil Association. Worthing,on. Ohio. 1986.
128.
39. Grbic-Gaiic. D. and Vogel, T. M., Transformation of toluene and benzene by mixed methanosenic culture,
Appt. Environ, Microbiol., 53. 255, 1987.
40. Vogel, T. E. and Grbic-Gallc, D., Incorporation of oxygen from water into toluene and benzene dun™
anaerobic fermentative transformation. Appl. Environ. Microbiol.. 52. 200 1986
41. Bouwer, E. J., Rittman, B. E., and McCarty, P. L., Anaerobic degradation of halogenated I- and '
carbon organic compounds. Environ. Sci. Techno!.. 15, 590, 1981.
42. Bouwer, E, J. and McCarty, P. L.. Transformation of I- and 2-carbon halogenated aliphatic oreanic
compounds under methanogenie conditions. Appl. Environ. Microbiol., 45. 1286, 1983
43. Suflita. J. M. and Gibson, S. A., Biodegradation of haloaromatic substrates in a shallow anoxic erour, i
water aquifer, in Proc. 2nd Int. Conf. on Ground Water Quality Res., Durham. N. N. and Redelfs A E
Eds., Oklahoma State University Priming Services, Stillwater. Okla., 1985, 30.
44. Alexander, M., Biodegradation of organic chemicals. Environ. Sci. Techno!.. 18. 106, 1985
45. Boethling, R. S. and Alexander, M., Effect of concentration of organic chemicals on their biodegradation
by natural microbial communities. Appl. Environ. Microbiol.. 37, 1211. 1979.
46 Lee, M. D., Biodegradation of Organic Contaminants in the Subsurface of Hazardous Waste Sites Ph D
thesis. Rice University. Houston, Tex.. 1986. 160. '
47 Hutchins, S. R., Tomson, M. B., Bedlent. P. B., and Ward. C. H., Fate of trace orean.es during land
application of municipal wastewater, CRC Crit. Rev. Environ. Control. 15, 355. 1985.
48. Zobdl, C. E., The effect of solid surfaces upon bacterial activity, J. Bacterial., 46, 39, 1943
49. Ogram, A. V., Jessup, R. E„ Ou, I. T„ and Rao, P. S. C., Effects of sorption on biological degradation
rates of (2.4-dichlorophenoxy) acetic acid in soils. Appl. Environ. Microbiol.. 49, 582. 1985.
50. Alexander, M., Soil Microbiology, John Wiley & Sons. New York. 1977, 467.
51. Hambrick. G. A., Ill, DeLaune, R. D., and Patrick. W. H., Jr., Effect of estuarine sediment pH and
oxidation-reduction potential on microbial hydrocarbon degradation, Appl. Environ Microbiol 40
1980.
52. McNabb. J. F. and Dunlap, W. J„ Subsurface biological activity in relation to ground water oolluiion
Ground Water. 13. 33. 1975.
53. Bartholomew, G. W. and Pfaender, F. K„ Influence of spatial and temporal variations on organic pollutant
biodegradation rates in an estuarine environment. Appl. Environ. Microbiol.. 45, |03, 1983.
54. Altai, R. M.. Effects of temperature and crude oil composition on petroleum biodegradation Aon! Mi
crobiol.. 30. 396. 1975. * ' '
55. Muikins-Phillips, G. J. and Stewart, J. E., Effect of environmental parameters on bacterial degradation
of Bunker C oil. crude oils, and hydrocarbons. Appl. Environ. Microbiol., 28, 915. 1974.
56. Williams, D. E. and Wilder, D. G„ Gasoline pollution of a ground water reservoir — a case hismrv
Ground Water, 9, 50. 1971.
57. McKee, J. E., Laverty, F, B.. and Hertel, R. M„ Gasoline in groundwater. J. Water Pollut Conf
Fed.. 44, 293. 1972.
58. Litchfield, J. H. and Clark. L. C., Bacterial Activity in Ground Waters Containing Petroleum Products
API Publication No. 4211. Committee on Environmental Affairs. American Petroleum Institute Washineton
DC., 1973. '
59. Let. M. D. and Ward, C. H.. Biological methods for the restoration of contaminated aquifers. J, Environ
Toxicol. Chem.. 4, 743, 1985.
60. Raymond. R. L., Reclamation of Hydrocarbon Contaminated Ground Water. U.S. Patent 3,846,290
November 5. 1974.
61. Raymond. R. L„ Jamison, V. W„ and Hudson. J. O.. Final Report on Beneficial Stimulation of Bacterial
Activity in Ground Water Containing Petroleum Products. Committee on Environmental Affairs. American
Petroleum Institute. Washington. D.C., 1975.
62. Raymond, R. L.. Jamison, V. W„ and Hudson, J. 0„ Beneficial stimulation of bacterial activity in
groundwaters containing petroleum products. AlChE Symp. Ser., 73. 390. 1976.
63. Jamison, V. W„ Raymond. R. L.. and Hudson. J. O., Jr., Biodegradation of high-octane gasoline in
groundwater. Dev. Ind. Microbiol., 16. 305, 1975
64. Jamison. V. W„ Raymond. R. L„ and Hudson. J. O.. Jr., Biodegradation of high octane gasoline in
Proc. 3rd Int. Bimleyradation Symp., Shaipley ,J. M.. and Kaplan. A. M.. Eds.. Appl ied Science Publisher*
Englewood. N.J., 1976. 187.
65. Roux, P. H.. Impact <>l site hydrogeology on in situ remediation strategies, in Proc. HAZPRO 'MS Yrmno
R. A., Ed., Pudvan Publishing, Northbrook. III., 1985. 284. ' . '
-------
Volume 18, Issue 1 (1988) 81
66. Brown. R. A., Longfield, J. Y„ Norris. R. D., and Wolfe. G. E., Enhanced bioreclamation: designing
a complete .solution to groundwater problems, presented at Water Pollution Control Fed. Ind Wastes S\mp..
Kansas City, Mo.. October 1985.
67. Josephson, J., Restoration of aquifers. Environ. Sci. Techno!., 17. 347A. 19X3.
68. Chaffee, W. T. and Weimar, R. A., Remedial programs for ground-water supplies contaminated by
gasoline, in Proc. 3rd Natl Svmp. on Aquifer Restoration and Ground Water Monitoring. Nielsen. D M..
Ed.. National Water Well Association. Worthington. Ohio. 1983. 39.
69. Yaniga. P. M. and Mulrv, J., Accelerated aquifer restoration', in situ applied techniques for enhanced
free product recovery/absorbed hydrocarbon reduction via bioreclamaiion. in Proc. NWWA/API Con), on
Petroleum Hydrocarbons and Organic Chemicals in Ground Water — Prevention. Detection and Resto-
ration. National Water Well Association. Worthington. Ohio. 1985, 421.
70. Kaufman. A. K., In situ biodegradation: the viable alternative. HAZ-NEWS. June—July. 1986. Hazardous
Waste Association of California. 1986.
71. Kuhimeier, P. D. and Sunderland, G. L., Biotransformation of petroleum hydrocarbons in deep unsat-
urated sediments, in Proc. NWWA/API Con/, on Petroleum Hydrocarbons and Organic Chemicals in Ground
Water — Prevention. Detection, and Restoration. National Water Well Association. Worthington. Ohio.
1986. 445.
72. Raymond. R. L.. Jamison. V. W.. Hudson. J. 0., Mitchell, R. E., and Farmer, V. E., Final report.
Field Application ol Subsurface Biodegradation of Gasoline in a Sand Formation. American Petroleum
Institute Project No. 307-77. Washington. D.C.. 1978.
73. Brubaker, G. R. and Crockett, E. L.. In situ aquifer remediation using enhanced bioreclamation. in
Proc. HAZMAT M. June 1986. Atlantic City. N.J.. in press.
74. Flalhman, P. E. and Githens, G. D„ In situ biological treatment of isopropanol. acetone, and tetrahv-
drofuran in the soil/groundwater environment, in Groundwater Treatment Technology. Nyer, E. K.. Ed..
Van Nostrand Reinhold. New York. 1985, 173.
75. Flalhman, P. E.. McCloskey, M. J., Vondrick, J. J., and Pimlett, D. M., In situ physical/biological
treatment of methylene chloride (dichloro'methane) contaminated groundwater, in Proc 5th Natl. Symp.
Exp. on Aquifer Restoration and Ground Water Monitoring. National Water Well Association. Worthington.
Ohio. 1985. 571.
76. Flalhman, P. E.. Quince. J. R., and Bottomlev, L. S., Biological treatment of ethylene glycol-contam-
inated.ground water at Naval Engineering Center in Lakehurst. New Jersey, in Proc. Jth Natl. Symp. on
Aquifer Restoration and Ground Water Monitoring, Nielsen. D. M. and Curl, M., Eds.. National Water
Well Association. Worthington. Ohio. 1984. III.
77. Raymond. R. L.. Environmental bioreclamaiion. presented at 1978 Mid-Continent Cant, and Exhibition
on Control of Chemicals and Oil Spills. Detroit. Mich.. September. 1978.
78. Minugh. E. M.. Patrv, J. J., Keech, D. A,, and Leek, W. R., A case history: cleanup of a subsurface
leak of refined product, in Proc. 1983 Oil Spill Conf. — Prevention, Behavior. Control, and Cleanup. San
Antonio. Tex.. March 1983. 397.
79. Brenoel. M. and Brown, R. A., Remediation of a leaking underground storage tank with enhanced
bioreclamation. in Proc. 5th Natl. Symp. Exp. on Aquifer Restoration and Ground Water Monitoring.
National Water Well Association. Worthington. Ohio. 1985. 527.
80. Jhaveri. V. and Mazzacca, A. J., Bio-reclamation of ground and ground water by in-situ biodegradation.
A case history, in Proc. 6th Natl. Conf. on Management of Uncontrolled Hazardous Waste Sues. Washinston.
D.C.. November 1985. 239.
81. Suntech Group. Vapors invade school; bioreclamation process cleans up ground water, microorganisms
devour spilled hydrocarbons. Petroleum Marketer. (July—August) 1978.
82. Jensen. B., Arvin. E., and Gunderson, A. T., The degradation of aromatic hydrocarbons with bacteria
from oil contaminated aquifers, in Proc. NWWA/API Conf. on Petroleum Hydrocarbons and Organic
Chemicals in Ground Water — Prevention, Detection, and Restoration. National Water Well Association.
Worthington. Ohio. 1986. 421.
83. Bouwer. E. J., Biotransformation of organic micropollutams in the subsurface, in Proc.,VWWA/API Conf.
on Petroleum Hydrocarbons and Organic Chemicals in Ground Water — Prevention. Detection, and
Restoration. National Water Well Association. Worthington. Ohio. 1985. 66.
84. Rittman. B. E. and Kobayshi, H.. Microbial separation for trace-organic removal, in Detoxification of
Hazardous Waste. Exner. J. H.. Ed.. Ann Arbor Science. Ann Arbor. Mich.. 1982. 323
85. Shimp, R. J. and Pfaender. F., Inlluence of easily degradable naturally occurring carbon substances on
biodegradation of monosubsmutcd phenols by aquatic bacteria. Appl. Environ. Microbiol . 49. 394. 1985
86. Yaniga, P. Matson, C., and Oemko, 0. J., Restoration of water quality in a multiaquiter system
via in situ biodegradation ol the organic contaminants, in Proc. 5th Natl. Sxmp. Exp. on Aquifer Restorontm
and Ground Water Monitoring. National Water Well Association. Worthington, Ohio. 1985. 510.
87. Brown. R. A., Norris, R. D., and Brubaker, G. R,, Aquifer restoration with enhanced bioreclamation.
Pollution Eng . (November) 25. 1985
-------
82 CRC Critical Reviews in Environmental Control
88. Quince. J. R.. Ohneck, R- J-> and Vondrik, J. J., Response lo an environmental incident affecting
ground water, in Proc. 5th Null. Symp. Exp. on Aquifer Restoration and Ground Water Mimitorim•, National
Water Well Association. Worthington. Ohio, 1985. 598.
89. Fiathman, P. E. and Caplan, J. A., Biological cleanup of chemical spills, in Proc. HAZMACOX '85.
Association of Bay Area Governments. Oakland, Calif., 1985.
90. Winegardner, D. L. and Quince, J. R., Ground water restoration projects: five case histories, in Proc.
4th Sail. Symp. Exp on Aquifer Restoration and Ground Water Monitoring, Nielsen, D. M. and Curl. M..
Eds., National Water Well Association, Wonhington. Ohio. 1984. 386.
91 Brown, R. A., Norris. R. D., and Raymond, R. L., Oxygen transport in contaminated aquifers, in Proc.
NWWA/API Conf. on Petroleum Hydrocarbons and Organic Chemicals in Ground Water — Prevention.
Detection, and Restoration. National Water Well Association.'wonhmgton. Ohio. 1984. 421.
92. Wilson. J. T. and Ward, C. H.. Opportunities for bioreclamation of aquifers contaminated with petroleum
hydrocarbons. J. Ind, Microbiol.. 21. 109. 1987,
93. Micheisen, D. L., Willis, D. A., and Lavinder, S. R., In situ biodegradation of dispersed organics using
a microdispersion of air in water, in Proc. 6th Natl. Conference on Management of Uncontrolled Hazardous
Waste Sites. Washington. D.C.. November 1985. 291.
94 Britlon, L. N. and Texas Research Institute, Inc., Feasibility Studies on the Use of Hydrogen Peroxide
to Enhance Microbial Degradation of Gasoline, 1985, 36, submitted to API. Washington. D C.
9.V Texas Research Institute, inc.. Enhancing the Microbial Degradation of Underground Gasoline by Increasing
Available Oxygen. Final report, American Petroleum Institute. Washington. D C.. 1982.
96. Brown. R. A., Norris, R. D„ and Westray, M. S.. In situ treatment of groundwater, presented at
HAZPRO '86, The Professional Certification Symp. and Exp.. Baltimore. Md.. Apnl 1986.
97. Ravmond, R. L., Brown. R. A.. Norris,.R. D.. and O'Neill. E. T.. Stimulation of Biooxidation Processes
in Subterranean Formations, U.S. Patent 4,588,506, May 13. 1986.
98 Yaniga, P. M., Alternatives in decontamination for hydrocarbon-contaminated aquifers, in Proc. 2nd Natl.
Svmp. on Aquifer Restoration and Ground Water Monitoring. Nielsen. D. M.. Ed.. National Water Well
Association. Wonhington, Ohio. 1982, 47.
99 Yaniga, P. M.. Smith. W.« and Raymond, R. L„ Biodegradation of Organic Compounds. Enhanced
Techniques lor Diffusion of Oxygen in the Groundwater System, prepared for Chemical Manufacturers
Association. Washington. D.C.. 1985.
100 Westrav. M. S., Brown. R. A., and Norris, R. D.. Groundwater Microbiology and Pollution Control.
FMC Aquifer Remediation Systems. Princeton. N.J.. 1985. 25.
101 Brown, R. A. and Norris. R. P.. Field demonstration of enhanced bioreclamation. presented at the 6th
Natl Symp. and Exp. on Aquifer Restoration and Ground Water Monitoring. Columbus. Ohio. May 1986.
101 L ' M D^, Wilson, J. T.. and Ward, C. H., In situ restoration techniques for aquifers contaminated
' w»h hazardous wastes. J¦ Hazard. Mater., 14. 71. 1987.
103 Wetzel R S., Henry. S. M.. Spooner, P. A., and Hevse, E.. In situ treatment oi contaminated ground-
water and soils Kelly Air Force Base. Texas, in Proc. Lund Disposal of Hazardous Wastes. 11th Anmt.
TJ s..mp u S. Environmental Protection Agency. Cincinnati. Ohio, I9K5.
Wetiel R S Durst, C. M., Sarno. D. J.. Spooner, P. A.. James. S. L\. and Heyse. E.. Demonstration
Of in situ biological'degradation of contaminated groundwater and soils, in Proc. t»h Natl. Conf. on
Management of Uncontrolled Hazardous Waste Sites. Hazardous Materials Control Research Institute.
Washington, D^C. '9^"an(j Wetzel, r., in situ biodegradation of aquifer contaminants at Kelly Air
'°5' Forct^Base presented at AlChe 1985 Annu. Meet.. Chicago. November 1985. paper 135c.
106 Science Applicauons International Corporation. Final report. Field Demonstration of In Situ Biological
' Degradation. Engtneering and Services Laboratory. Air Force Engineering and Services Center. TyndalI
Air Force Base. Fla. and U.S. Environmental Protection Agency. Hazardous Waste Engineering Research
107 WrtMl'°R SC'DavWson, D. A., Durst, C. M.. and Sarno. D. J., Field demonstration of in situ biological
treatment of contaminated groundwater and soils, in Pr,K. 12th Aim*. Environ. Protection Agency Res,
Svmp. on Land Disposal, Remedial Aition, Incineration ami Treatment o) Hazardous Wastes, Cincinnati.
... Ph'"' 'r 6 K„i.hn W Werner, P., awl Sontheimer. H.. Sanitation of ground water bv infiltration of
109 Cow W. L. and Minugh. E.. Subsurface venting of vapors emanating from hydrocarbon product on
i ' d water ' in Proc NWWAlAPI Conf. rw Petroleum Hydrocarbons ami Organic Chemicals in Ground
Z Prevention. Detection, and Restoration. National Water Well Association. Wonhington. Ohio.
I¥85, 536.
104
-------
Volume 18, Issue 1 (1988) 83
110. Coia, M. F., Corbin, M. H-. and Anastos, G., Soil decontaminaiion ihrough in-situ air stripping of
volatile organics — a pilot demonstration, in Proc. NWWA/API Conf. on Petroleum Hydrocarbons and
Organic Chemicals in Ground Water — Prevention, Detection, and Restoration. National Water Well
Association, Wonhington, Ohio. 1985. 555.
111. Agrelot, J. C., Malot, J. J., and Visser, M. J., Vacuum: defense system for groundwater VOC contam-
ination. in Proc. 5th Natl. Symp. on Aquifer Restoration and Ground Water Monitoring. National Water
Well Association. Worthington. Ohio, 485. 1985.
112. Malot, J. J., Unsaturated zone monitoring and recovery of underground contamination, in Prot. 5th Null
Symp. Exp. on Aquifer Restoration and Ground Water Monitoring. National Water Well Association.
Wonhington. Ohio, 1985. 539.
113. J. R. B. Associates. Handbook for Remedial Action at Waste Disposal Sites. EPA-625/6-82-006. U.S.
Environmental Protection Agency. Cincinnati. Ohio. 1982.
114. Yang, J. T. and Bye, W. E., Protection of Ground Water Resources from the Effects of Accidental Spills
of Hydrocarbons and Other Hazardous Substances (Guidance Document), Technical report. EPA-57U.9-7W-
017. Environmental Protection Agency. Washington. D.C., 1979. 166.
115. Loehr, R. C. and Malina, J. F., Jr., Eds., Land Treatment. A Hazardous Waste Management Alternative.
Water Resources Symp. No. 13. Center for Research in Water Resources. University of Texas at Austin.
Tex.. 1986. 369.
116. Ross, D. E. and Phung, H. T.. Soil incorporation (landfarming) of industrial wastes, in Toxic and
Hazardous Waste Disposal, Vol. 4. New and Promising Ulitmate Disposal Options. Pojasek. R. B.. Ed..
Ann Arbor Science. Ann Arbor. Mich.. 1980. 291.
117. Huddleston. R. L.. Bleckmann. C. A., and Wolfe, J. R„ Land treatment biological degradation processes,
in Land Treatment, A Hazardous Waste Management Alternative, Water Resources Symp. No. 13. Loehr.
R. C. and Malina, J. F.. Jr.. Eds.. Center for Research in Water Resources. University of Texas at Austin.
Tex., 1986. 41.
118. Relbel, D. D. and Wetzel, D. M„ A literature survey of three selected hazardous waste destruction
techniques, in Land Disposal of Hazardous Wastes. Proc. 9th Annu. Res. Symp., Shultz. D. W. and Black.
D., Eds.. EPA-600/9-83-018. U.S. Environmental Protection Agency. Washington. D C.. 1983
119. Ryan, J., The land treatability of Appendix VIII organics presented in petroleum wastes, in Land Treatment.
A Hazardous Waste Management Alternative, Water Resources Symp. No. 13. Loehr. R. C.. and Malina.
J. F., Jr., Eds.. Center for Research in Water Resources. The University of Texas at Austin. Tex.. 1986.
347.
120. Law Engineering Testing Company. Literature inventory. Treatment Techniques Applicable to Gasoline
Contaminated Ground Water. American Petroleum Institute, Washington. D.C.. 1982.
121. Kebc, J. D. and Brockman, G. T., Report to the American Petroleum Institute for an Evaluation of the
Natural Fate of Aqueous Gasoline and Treatment Alternatives. Task IB — Literature Survey: Unassisted
Natural Mechanisms to Reduce Concentrations of Soluble Gasoline Components. American Petroleum
Institute, Washington. D.C., 1984.
122. Dibble, J. T. and Bartha, R.. Rehabilitation of oil-inundated agricultural land: a case history . Soil Set.,
128, 56. 1979.
123. Col well, R. R. and Walker, J. D., Ecological aspects of microbial degradation of petroleum in the marine
environment. CRC Crit. Rev. Microbiol., 5, 423, 1977. '
124. Mulkins-Phillips, G. J. and Stewart, J. E., Effect of four dispersants on biodegradation and growth of
bacteria on crude oil. Appl. Microbiol., 28, 547, 1974a.
125. Texas Research Institute, Inc., Final report. Underground Movement of Gasoline on Groundwater and
Enhanced Recovery by Surfactants, submitted to American Petroleum Institute. Washington. D C.. 1979.
126. Ellis. W. D„ Payne, J. P.. Tafurl, A. N„ and Freestone. F. J„ The development of chemical coun-
termeasures for hazardous waste contaminated soil, in 1984 Hazardous Material Spills Conf. Proc —
Prevention, Behavior, Control, and Cleanup of Spills and Waste Sites, Ludwigson. J., Ed., Government
Institutes, Inc.. Rockville, Md.. 1984, 116.
127. Atlas, R. M-, Stimulated petroleum biodegradation. CRC Crit. Rev. Microbiol., 5. 371, 1977.
128. Robictiaux, T. J. and Myrick. H. N„ Chemical enhancement of the biodegradation of crude-oil pollution.
(tf Petroleum Techno!.I January) 16. 1972.
129. Broderkk, L. S. and Cooney, J. J., Emulsification of hydrocarbon by bacteria from freshwater ecosystems.
Dev. Ind. Microbiol.. 23. 425. 1981.
130. Vanlooke, R.. Verllnde. A., Verstraete. W„ and DeBorger. R„ Microbial release of oil from soil
columns. Environ. Sci. Techno!., 13. 346. 1979.
131. Ehrlich, G. G., Schroeder. R. A., and Martin, P., Microbial populations in a jet fuel contaminated
shallow aquifer at Tustin. Calilomia. U.S. Geological Survev Open-File Report 85-335. Sacramento. Calif..
1985, 14.
-------
84 CRC Critical Reviews in Environmental Control
132. Wilson. $. B., In silu biosurfactam production: aid 10 the biodegradation of organic ground water contam-
inants. in Proc. NWWA/API Cimf. on Petroleum Hydrocarbons and Organic Chemicals in Ground Water
— Prevention, Detection and Restoration. National Water Well Association. Worthington. Ohio. 19X6.
436.
133. Wilson, J. T., Leach, L. E., Henson. M. J., and Jones, J. N., In situ biorestoration as a ground-water
remediation-technique. Ground Water Monir. Rev., Fall. 56. 1986.
134. Clark, J. B„ Munnecke, D. M., and Jenneman, G. E., In situ microbial enhancement of oil production.
Dev. Ind. Microbiol., 22, 695, 1981.
135. Zajic, J. E. and Akit, J„ Biosurfactants in bitumen separation from tar sands, in Microbial Enhanced Oil
Recovery, Zajic. J. E., Coo per. D. G., Jack. T. R., and Kosanic. N.. Eds.. Penn Well Books. Tulsa
Okla.. 1983. 50.
136. Lazar, I., Some characteristics of the bacterial inoculum used for oil release from reservoirs, in Microbial
Enhanced Oil Recovery, Zajic, J. E., Cooper. D. G., Jack. T. R.. and Kosari. N.. Eds.. Pennwell Books.
Tulsa. Okla.. 1983. 73.
137. Wilson, J. L. and Conrad, S. H„ Is physical displacement of residual hydrocarbons a realistic possibility
in aquifer restoration?, in Proc. NWV/AIAPI Conf. on Petroleum Hydrocarbons and Organic Chemicals in
Ground Water — Prevention. Detection and Restoration, National Well Water Association. Worthington.
Ohio. 1986.
138. Paulson. D. L„ Jr., HoneycuU, R„ Lebaron, J„ and Selm, V„ Degradation of high concentrations of
diazinon in soil by parathion hydrolase, in I9H4 Hazardous Material Spills Conference Proc. — Prevention.
Behavior, Control, and Cleanup of Spills and Wasre Sites. Ludwigson. J.. Ed.. Government Institutes.
Inc.. Rockville. Md., 1984, 92.
139. Ehrenfdd, J. and Bass, J., Evaluation of Remedial Action Unit Operations of Hazardous Waste Disposal
Sites. Pollution Technology Review No. 110. Noyes Publications. Park Ridge. N.J.. 1984. 215.
140. Borden, R. C. and Bedient. P. B„ Transport of dissolved hydrocarbons influenced by reaeration and
oxygen limited biodegradation. I. Theoretical development. Water Resour. Res.. 22. 1973. 1986.
141. Borden, R. C„ Bedient, P. B.. Lee. M. D., Ward, C. H., and Wilson, J. T., Transport of dissolved
hydrocarbons influenced by reaeration and oxygen limited biodegradation. II. Field application. Water
Resour. Res.. 22. 1983. 1986.
142. Bouwer, H„ Elements of soil science and groundwater hydrology, in Groundwmer Pollution Microbiology,
Bitton, G. and Gerba, C. P.. Eds.. John Wiley & Sons. New York. 1984. 9.
143. Downes, C. J., Redox reactions, mineral equilibria, and ground water quality in New Zealand aquifers,
in Ground Water Quality, Ward. C. H., McCarty. P. L.. and Giger. W., Eds.. John Wiley & Sons. New
York. 1985. 94.
144. Bouwer, E. J. and McCarty, P. L„ Transformationofhalogenatedorganiccompounds under denitrification
conditions. Appl. Environ. Microbiol., 45, 1295, 1983.
145. Eltrlich, G. G., Goerlitr. D. F.. Godly, E. M„ and Hull, M, F„ Degradation of phenolic contaminants
in ground water by anaerobic bacteria: St. Louis Park. Minnesota. Ground Water. 20. 702. 1982.
146. Van Engers. L.. Mineralization of organic matter in the subsoil of a waste disposal site: a laboratory
experiment. Soil Sci., 126, 22. 1978.
147 Canons. F„ Lage, G. B„ and Rice, R., Biotransformation of chlorinated organic solvents in static
microcosms. Environ. Toxicol. Chem., 4, 739, 1985.
148. Vogel, T. M. and McCarty, P. L„ Biotransformation of tetrachloroethylene to trichloroethylene. di-
ehloroethylene, vinyl chloride and carbon dioxide under methanogenic conditions. Appl. Environ. Micro-
biol.. 49. 1080. 1985.
149. Wood, P. R.. Lang. F > Md Ptyal. '• Anaerobic transformation, transport, and removal of volatile
chlorinated organics in ground water, in Ground Water Quality. Ward. C. H.. Giger. W,, and McCanv
P. L.. Eds., John Wiley & Sons. New York, 1985. 493.
150. Tiedje, J. M., Boyd. S. A„ and Fathepure, B. Z„ Anaerobic degradation of chlorinated aromatic
hydrocarbons. Dev. !nd. Microbiol., 27, 117, 1987.
IS I. Batterman. G„ A large scale experiment on in situ biodegradation of hydrocarbon in the subsurface, in
Ground Water in Wafer Resources Planning Volume II. Proc. Int. Symp., IASA Publication 142. Inter-
national Association of Hydrological Sciences. London. 1983. 983.
152. Batterman, G. and Werner, P., Beseiiigung einer umergrundkontamination mit kohienwasserstoffen durch
mikrobiellcn abbau. GWF-WasstriAbwasser, 125. 366, 1984,
153. McCarty, P. L,. Application of biologjpi transformation in ground water, in Proc. 2nd hi, Conf. on
Groundwater Quality Research. Durham. N. N. and Redelfs. A. E., Eds.. Oklahoma State University
Priming Services. Stillwater. 1985. 6.
154. Fogel, S„ Lancione, R. L„ and Scwall, A. E„ Enhanced biodegradation of methoxychlor jn soil under
sequential environmental conditions. Appl. Environ, Microbial., 44, 113. 1982.
-------
Volume 18, Issue 1 (1988) 85
155. Spain, J. C., Pritchard. P. H., and Bourquin, A. W.. Effects of adapiaiion on biodegradation rales in
sediment/water cores from estuarine and freshwater environments. Appl. Environ. Microbiol. 40. 726.
1980.
156. Ghosal, D.. You, L. S., Chatterjee. O. K., and Chakrabartv, A. M., Microbial degradation of halo-
genaled compounds. Science, 228. 135. 1985.
157. Kilbane. J .. Genetic aspects of toxic chemical degradation. Microb. Ecol.. 12. 135. 1986.
158. Zitrides, T. G., Mutant bacteria for the disposal of hazardous organic wastewaters, presented at Pesticide
Disposal Res. and Dev. Svmp.. Reston, Va.. September 1978.
159. Kopeckv, A. L., Improved removal of oligineous substances with mutant bacteria, in Impact of Applied
Genetics in Pollution Control, papers presented at a Symp., Kulpa. C. F., Jr.. Irvine. R. L.. and Sojka.
S. A.. Eds.. Notre Dame. Ind.. 1982, 143.
160. Birge, E. A., Bacterial and Bacteriophage Genetics. An Introduction, Springer-Verlag. New York. 1981.
359.
161. Pierce, G. E., Development of genetically engineered microorganisms to degrade hazardous organic com-
pounds. in Hazardous Waste Management for the I980's, Sweeny. T. L.. Bhatt. H. G.. Sykes. R. N .
and Sproul. O. J.. Eds.. Ann Arbor Science. Ann Arbor. Mich.. 1982. 431.
162. Johnston. J. B. and Robinson, S. G., Development of new pollution control technologies: opportunities
and problems, in Impact of Applied Generics in Pollution Control, papers presented at a Symp.. Kulpa.
C. F.. Jr.. Irvine. R. L., and Sojka. S. A.. Eds.. Notre Dame. Ind.. 1982a. 1.
163. Kilbane, J. J., Chatterjee, D. K., Karns, J. S.. Keliog, S. T., and Chakrabarty. A. M.. Biodegradation
of 2.3.5-trichlorophenoxyacetic acid by a pure culture of Pseudomonas cepacia. Appl. Environ. Microbiol..
44. 72. 1982.
164. Kellog, S. T., Chatterjee, D. K.. and Chakrabarty, A. M., Plasmid-assisted molecular breeding: new
techniques for enhanced biodegradation of persistent toxic chemicals. Science. 214. 1133. 1981.
165. Kilbane. J. J., Chatterjee, D. K.. and Chakrabarty, A. M., Detoxification of 2.4.5-trichlorophenox-
yacetic acid from contaminated soil by Pseudumonas cepacia, Appl. Environ. Microbiol.. 45. 1697, 1983.
166. Chatterjee, D. K., Kilbane. J. J., and Chakrabarty, A. M., Biodegradation of 2.4.5-trichlorophen-
ox yacetic acid in soil by a pure culture of Pseudomonas cepacia. Appl. Environ. Microbiol.. 44. 514. 1982.
167. Coiaruotolo. J. F., Olsen. R. H.. and Vandenbergh, P. V., Microbial Degradation of Obnoxious Organic
Wastes Into Innocuous Materials. U.S. Patent 4.493.895, January 15. 1985.
168. Joyce. C.. Engineered organisms in the environment — who is responsible.'. Bioscience, 33. 538. 1983
169. Fox. J. L., Fixed up in Philadelphia: genetic engineers meet with ecologists. ASM News. 51. 382. 19X5
170. Liang. L. N.. Sinclair. J. L., Mallory, L. M., and Alexander, M., Fate in model ecosystem of microbial
species of potential in genetic engineering. Appl. Environ. Microbiol.. 44. 708. 1982.
17). Goldstein. R. M.. Mallory, L. M.. and Alexander. M., Reasons for possible failure of innoculation to
enhance biodegradation. Appl. Environ. Microbiol.. 50. 977. 1985.
172. Zajic, J. E. and Daugulis, A. J.. Selective enrichment processes in resolving hydrocarbon pollution
problems, in Impact of the Use of Microorganisms on the Aquatic Environment, Bourquin. A. W . Abeam.
D. G.. and Meyers, S. P., Eds.. EPA 660/3-75-001. U.S. Environmental Protection Agency. Corvallis,
Ore.. 1975. 169.
173. Omenn, G. S., Genetic control of environmental pollutants: a conference review. Microb Ecol.. 12. 129.
1986.
174. Johnston, J, B. and Robinson. S. G., Opportunities for development of new detoxification processes
through genetic engineering, in Detoxification of Hazardous Waste, Exner. J. H.. Ed.. Ann Arbor Science.
Ann Arbor. Mich., 1982. 301.
175. Atlas, R. M. and Bartha, R.. Effects of some commercial oil herders, dispersants, and bacterial inocula
on biodegradation of oil in sea water, in Proc. Microbial Degradation of OH Pollutants. Ahearn. D. G..
Cook. W. L., and Meyers, S. P., Eds.. Louisiana State University, Baton Rouge. 1973. 32.
176. Atlas, R. M. and Busdosh, M., Microbial degradation of petroleum in the arctic, in Proc. 3rd Int.
Biodegradation Svmp.. Sharplev, J. M. and Kaplan. A. M.. Eds.. Applied Science Publishers. London.
1975. 79.
177. Gutnkk, D. L. and Rosenberg, E., Oil tankers and pollution: a microbiological approach. Annu. Rev.
Microbiol.. 31, 379, 1977.
178. Wetzel, R. S., Foulch. R., Hardwell, W, E., Jones, W. E., and Kitchens. J. F„ Restoring Hazardous
Spill-Damaged Areas; Technique Identification/Assessment. EPA-600/2-81-208. U.S Environmental Pro-
tection Agency. Cincinnati. Ohio. 1981.
179 Daughton, C. G. and Hsieh. D. P. H., Accelerated parathion degradation in soil by inoculation with
parathion-utilizing bacteria. Bull. Environ. Contam. Toxicol.. 18. 48, 1977.
180. Focht, D. D. and Brunner, W., Kinetics of biphenyl and polychloiinated biphenyl metabolism in soil.
Appl. Environ. Microbiol.. 50. 1058. 1985.
181. Schwendinger, R, B.. Reclamation of soil contaminated with oil. J. Inst. Pet.. 54, 182, 1968
-------
86 CRC Critical Reviews in Environmental Control
182. Jobson, A., McLaughlin, M., Cook, F. D., and Westlake, D. W. S., Effects of amendments on the
microbial utilization of oil applied to soil. Appl. Environ. Microbiol., 27. 166. 1974.
183. Lehtomaki, M. and Niemela, S., Improving microbial degradation of oil in soil. Ambio, 4. 126. 1975.
184. Hunt, P. G., Richard, W. E., Deneke, F. J., Koutz, F. R., and Murman, R. P., Terrestrial oil spills
in Alaska: environmental effects and recovery, in Proc. Joint Conf. on Prevention and Control (if Oil Spills.
American Petroleum Institute. Silver Spring. Md., 1981, 288.
185. Westlake, O. W. S., Jobson, A. M., and Cook, F. D., In situ degradation of oil in a soil of the Boreal
region of the Northwest Territories. Can. J. Microbiol., 24. 254. 1978.
186. Jobson, A.. Cook, F. D., and Westlake, D. W. S., Microbial utilization of crude oil. Appl. Microbiol..
23. 11082. 1972.
187. Martinson, M. M., Steiert, J. G., Saber, D. L., and Crawford, R. L., Microbiological degradation of
pentachlorophenol in natural waters, in Biodegradation 6th Proc. 6th Int. Symp., O'Rear, E. E.. Ed..
Commonwealth Agricultural Bureau. Washington, D.C.. 1984.
188. Crawford, R. L. and Mohn. W, E.. Microbiological removal on pentachlorophenol from soil using a
Flavobacterium, Enzyme and Microb. Technol., 7,617. 1985.
189. Steiert, J. G. and Crawford, R. L., Microbial degradation of chlorinated phenols. Trends Biotechnoi.
3. 300. 1985.
190. Finn, R. K., Use of pure strains in treating toxic wastes and contaminated soil, in Impact of Applied
Genetics in Pollution Control, papers presented at a Symp.. Kulpa, C. F.. Jr.. Irvine. R. L.. and Sojka.
S. A.. Eds., Notre Dame. Ind., 1982. 91.
191. Edgehill, R. U. and Finn, R. K., Microbial treatment of soil to remove pentachlorophenol. Appl. Environ.
Microbiol.. 45. 1122. 1983.
192. Brown, E. J„ Plgnatello, J. P., Martinson, M. M., and Crawford, R. L., Pentachlorophenol degradation:
a pure bacterial culture and an epilithic microbial culture, Appl. Environ. Microbiol., 52, 92, 1986.
193. Jenneman, G. E., Knepp, R. N„ Mclnerney, J, J., Menzie. D. E., and Revus, D. E„ Experimental
studies of in-situ microbial enhanced oil recovery, Soc. Pet. Eng. J.. February, 33. 1984.
194. Jenneman, G. E., Mclnerney, M. J., and Knapps, R. M., Microbial penetration through nutrient-
saturated Berea sandstone. Appl. Environ. Microbiol., 50, 383, 1985.
195. Hagedorn, C., Microbiological aspects of groundwater pollution due to septic tanks, in Groundwater
Pollution Microbiology, Bitton, G. and Gerba, C. P., Eds.. John Wiley & Sons. New York. 1984, 181.
196. Gerba, C. P., Microorganisms as groundwater tracers, in Groundwater Pollution Microbiology. Bitton.
G. and Gerba. C. P.. Eds.. John Wiley & Sons. New York. 1984, 225.
197. Smith, M. S., Thomas, G. W„ and White, R. E., Movement of bacteria through macropores to ground
water. Research report 139, Water Resources Research Institute, University of Kentucky, Lexington. U.S.
Department of Interior, 1983.
198. McDowell, C. S., Bourgeois, H. J., Jr., and ZUrides, T. G., Biological methods for the in-situ cleanup
of oil spill residues, presented at Coastal and Off-Shore Oil Pollution Conf.. The French/American Ex-
perience. New Orleans, September 1980.
199. Walton, G. C. and Dobbs, D., Biodegradation of hazardous materials in spill situations, in Proc. 1981
Natl. Conf. on Control of Hazardous Material Spills. Louisville. Ken.. 1980. 23.
200. Quince, J. R. and Gardner, G. L., Recovery and treatment of contaminated ground water. I. Ground
Water Monit. Rev.. 2. 18, 1982.
201. Quince, J. R. and Gardner, G. L., Recovery and treatment of contaminated ground water. II, Ground
Water Monit. Rev.. 2, 18. 1982.
202. Ohneck, R. J. and Gardner, G. L„ Restoration of an aquifer contaminated by an accidental spill of
organic chemicals. Ground Water Monit. Rev., 50. 53. 1982.
203. Sikes, D. J„ McCulloch, M. N„ and Blackburn, J. W.,The containment and migration of a formaldehyde
rail car spill using novel chemical and biological in situ treatment techniques, in I9M4 Hazardous Material
Spills Conf. Proc. — Prevention. Behavior, Control, and Cleanup of Spills and Waste Sites. Ludwigson.
J.. Ed.. Government Institutes. Inc., Rockville. Md.. 1984. 38.
204. Wilson, J. T. and McNabb, J. F., Biological transformation of organic pollutants in groundwater, EOS,
64. 505, 1983.
205. Wilson, J. T., Enfield, C. G„ Dunlap, W. J„ Cosby, R. L„ Foster, D. A., and Basking, L. B.,
Transport and fate of selected organic pollutants in a sandy soil. J. Environ. Qttal., 10, 501. 1981.
206. Wilson, J. T. and Wilson, B. H., Biotransformation of trichloroethylene in soil. Appl. Environ. Microbiol..
49.242.1985.
207. Fogel. M. M., Taddeo, A. R„ and Fogel. S., Biodegradation of chlorinated ethenes by a methane-utilizing
mixed culture. Appl. Environ. Microbiol.. 51, 720. 1986.
208. Strand, S. E. and Shippert, L., Oxidation of chloroform in aerobic soil exposed to natural gas. Appl.
Environ. Microbiol.. 52. 203, 1986.
-------
Volume 18, Issue I (1988) 87
209. Hemon. J. M., Cochran, J. W., and Wilson, J. T.. Aerobic biodegradation of halogenated aliphatic
hydrocarbons, presented at the 6th Annu. Meet. Soc. Environ. Toxicol. Chem.. St. Louis. Mo.. November
1985. 100.
210. Henry, S. M. and Grbic-Galic. D., Aerobic degradation of irichloroethvlene (TCE) by methylotrophs
isolated from a contaminated aquifer, presented at the 86th Annu. Meet. Am. Soc. Microbiol.. Washington.
D C., March-1986, Q-64.
211. Wilson, B. H. and White, M. V., A fixed-film bioreactor to treat trichlnroethylene-laden waters from
interdiction wells, in Proc¦ 6th Nait. Symp and Exp. on Aquifer Restoration and Ground Water Monitoring.
National Water Well Association. Columbus. Ohio, 1986.
212. U.S. Environmental Protection Agency. National primary drinking water regulations: volatile synthetic
organic chemicals. Fed. Reg.. 49. 24330, 1984.
213. Henson, J. M.. Nichols, P. D., and Wilson, J. T., Degradation of halogenated aliphatic hydrocarbons
by a biochemically defined microbial community, presented at the 86th Annu. Meet. Am. Soc. Microbiol..
Washington, D C., March 1986. Q-l.
214. Barrio-Lage, G., Parsons, F. Z., Nassar, R. S.. and Lorenzo, P. A., Sequential dehafogenation of
chlorinated ethenes. Environ. Sci. Techno!.. 20, 96. 1986.
215. Hartman, S., DeBont, J. A. M., Tramper, J., and Luyben, K. C. A. M., Bacterial degradation of
vinyl chloride. Biotechnol. Lett.. 7. 383. 1985.
216. Janssen, D. B., Scheper. A., Dijkhuizen, L., and Witholt, B,, Degradation of halogenated aliphatic
compounds by Xanthobacter autotrophics GJ10. Appl. Environ. Microbiol.. 49. 673. 1985.
217. Shuckrow, A. J., Pajak. A. P., and Touhill, C. J., Management of Hazardous Waste Leachate. SW-
871. U.S. Environmental Protection Agency. Washington. D.C.. 1980.
218. Nyer, E. K., Groundwater Treatment Technology, Von Nostrand Reinhold. New York. 1985. 188.
219. Canter, L. W. and Knox, R. C., Ground Water Pollution Control. Lewis Publishing. Chelsea. Mich..
1985. 526.
220. Eckenfelder, W. W., Jr., Patoczka, J„ and Watkin, A. T., Wastewater treatment. Chem. Eng . 2. 60.
1985.
221. Ying, W„ Beck. R. R.,'Lloyd. U. J., and Sojka, S. A., Biological treatment of a landfill leachate in
sequencing batch reactors. Environ. Prog.. 5, 41, 1986.
222. Wilkinson, R. R., Kelso, G. L., and Hopkins, F. C.,State-of-the-Art Report: Pesticide Disposal Research.
EPA-60CV2-78-183, U.S. Environmental Protection Agency. Cincinnati. Ohio. 1978.
223. Absalon. J. R. and Hockenbury, M. R„ Treatment alternatives evaluation for aquifer restoration, in
Proc. JrdNatl. Symp. on Aquifer Restoration and Ground Water Monitoring. Nielsen. D. M.. Ed.. National
Water Well Association. Worthington. Ohio, 1983. 98.
224. Chian, E. S. K„ Stability of organic matter in landfill leachates, Water Res.. II. 225. 1977.
225. Stover, E. and Kincannon. D. F., Treatability studies for aquifer restoration, presented at 1982 Joint
Annu. Conf. Southwest and Texas Sections. American Water Works Association. Oklahoma City, Okla..
1982.
226. Shuckrow, A. J. and Pajak, A. P., Bench scale assessment of concentration technologies for hazardous
aqueous waste treatment, in Land Disposal: Hazardous Waste, Shultz, D. W., Ed.. EPA-600/9-8l-(M)2b.
U.S. Environmental Protection Agency, Cincinnati. Ohio. 1981.
227. James, S. C„ Shuckrow, A. J., and Pajak, A. P.. History and bench scale studies for the treatment ot
contaminated groundwater at the Ott/Story Chemical Site. Muskegon. Michigan, in Proc. ,\'atl. Conf. mi
Management of Uncontrolled Hazardous Sites. Hazardous Material Control Research Institute. Silver Spring.
Md.. 1981. 288.
228. Schaczler. D. J. and St. Clair. J. H.. Ground water treatment system design, in Proc NWWAAPI C
-------
88
CRC Critical Reviews in Environmental Control
235. Ozbilgin, M. M. and Powers, M. A.. Hydrodvnamic isolation in hazardous waste containment, in Proc.
4th Natl. Synip. on Aquifer Restoration and Ground Water Monitoring. Nielsen. D. M.. Ed.. National
Water Well Association. Worthington. Ohio. 1984, 44.
236. Shafcr, J. M., Determining optimum pumping rates for creation of hydraulic barriers to ground water
pollutant migration, in Proc. 4th Nail. Symp. on Aquifer Restoration and Ground Water Monitoring. Nielsen.
D. M.. Ed.. National Water Well Association. Worthington. Ohio. 1984. 50.
237. Gorelick, S. M., A model for managing sources of ground water pollution. Water Resour. Res.. 18. 773.
1982.
238. Atwood, D. F. and Gorelick, S. M., Optimal hydraulic containment of contaminated ground water, in
Proc. 5th Natl. Symp. on Aquifer Restoration and Ground Water Monitoring, National Water Well As-
sociation, Worthington. Ohio, 1985. 328.
239. Anderson, M. P., Using models to simulate the movement of contaminants through ground water flow
systems, CRC Crit. Rev. Environ. Control, 9, 96, 1979.
240. Javandel, I., Doughty, C., and Tsang, C. R., Ground Water Transport: Handbook of Mathematical
Models. Water Resources Monograph Series. American Geophysical Union. Washington. D.C.. 1984.
241. Monod, J., Recherches sur la Croissance des Cultures Bacteriennes. Herman & Cie. Paris. 1942.
242. Herbert, D., Elsworth. R. E., and Telling, R. C., The continuous culture of bacteria: a theoretical and
experimental study. J. Gen. Microbiol.. 14. 601, 1956.
243. Yoon, H„ Klinzing, G., and Blanch, H. W„ Competition for mixed substrates by microbial populations.
Biotechnol. Bioeng.. 19. 1193. 1977.
244. Schmidt, S„ Slmkins. S., and Alexander, M., Models for the kinetics of biodegradation of organic
compounds not supporting growth. Appl. Environ. Microbiol., 50. 323. 1985.
245. Heukelekian, H. and Heller, A., Relation between food concentration and surface for bacterial growth,
J. Bacterial.. 46. 39, 1943.
246. Williamson, K. and McCarty, P. L., A model of substrate utilization by bacterial films. J. Water Pollut.
Com. Fed.. 48. 9, 1976.
247. Rittman, B. E. and McCarty, P. L., Mode/ of steady-state biofilm kinetics, Biotechnol. Bioeng.. 22.
2343. 1980.
248. Bouwer, E, J. and McCarty, P. L., Modeling of trace organics biotransformation in the subsurface.
Ground Water, 22. 433. 1984.
249. Kissel, J. C., McCarty, P. L.. and Street. R. L„ Numerical simulation of mixed-culture biofilm. J.
Environ. Eng. Div. ASCE, 110, 393, 1984.
250. Molz, F. J., Widdowson. M. A., and Benefleld, L. D., Simulation of microbial growth dynamics coupled
to nutrient and oxygen transport in porous media. Water Resour. Res.. 22. 1207, 1986.
251. Keely, J. F., Piwoni, M. D,, and Wilson, J. T., Evolving concepts of subsurface contaminant transport.
J. Water Pollut. Com. Fed., 58. 349. 1986.
252. Freeze, R. A. and Cherry, R. B., Ground Water. Prentice Hall, Englewood Cliffs. N.J.. 1979.
253. Weber, W. J„ Phystochemical Processes for Water Quality Control, John Wiley & Sons. New York.
1972.
254. Fried, J. J., Ground Water Pollution, Elsevier, Amsterdam. 1975.
255. Anderson, M. P., Movement of contaminants in groundwater transport: advection and dispersion. Ground-
water Contamination. National Research Council. Academic Press, Washington. D C.. 1981.
256. Ogata, A. and Banks, R. B., A solution for the differential equation of longitudinal dispersion in porous
media. U.S.G.S. Professional Paper 1961, 4II-A.
257. Wilson, J. I- and Miller, P. J.. Two-dimensional plume in uniform groundwater How. J. Hydro!. Div.
ASCE. 10. 503. 1978.
258. Simkins, S. and Alexander. M., Models for mineralization kinetics with the variables of substrate con-
centration and population density. Environ. Microbiol., 47, 1299, 1984.
259. Mercer. J. W. and Faust, C. R.. Ground-Water Modeling, National Water Well Association. Worthington.
Ohio. 1981.
260. Prickett. T. A., Modeling techniques for groundwater evaluation, in Advances in Hydroscience, Vol. 10.
Academic Press, New York. 1975.
261. Pinder, G. R. and Gray, W. G., Finite Element Simulation in Surface and Hydrology, Academic Press.
New York, 1977.
262. Wang, H. F. and Anderson, M. P.. Introduction to Groundwater Modeling. W. H. Freeman. San
Francisco. 1982.
263. Konikow, L. F. and Bredeheoft. J. D., Computer Model of Two-Dimensional Solu(e Transport and
Dispersion in Ground Water. Automated Data Processing and Computations. Techniques of Water Resources
Investigations of the U.S. Geological Survey. Washington. D C., 1978.
264. Kosson. D. S.. Agnihotri, G. C„ and Ahlert, R. C., Modeling of microbials active soil columns, in
Computer Applications in Water Resources ASCE. Tomo. H. C,. Ed.. American Society of Civil Engineers.
New York. 1985.
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Volume 18, Issue 1 (1988) 89
265. Angelakis, A. N. and Rolston, D. E.. Transient movement and transformation of carbon specie* in soil
during wastewater application. Water Resour. Res., 21. 1141, 1985.
266. Baehr, A. and Corapciogiu, M. Y.. A predictive model for pollution from gasoline in soils and ground-
water. in Proc. NWWAIAPI Conf. on Petroleum Hydrocarbons and Organic Chemicals in Ground Water
— Prevention. Detection, and Restoration. National Water Well Association. Wonhington. Ohio. 1985,
144.
267. Sykes, J. F.. So.vupak, S., and Farquhar, G. J., Modeling of leachate organic migration and attenuation
in ground waters below sanitary landfills. Water Resour. Res.. 18, 135, 1982.
268. Dawson. C. N., Wheeler, M. F., and Borden, R. C., Numerical simulation of microbial biodegradation
of hydrocarbons in groundwater, in Proc. Conf. on Finite Elements in Flow Problems VI. Antibes. France.
June. 1986.
269. Lee, M. D. and Ward, C. H., Reclamation of contaminated aquifers: biological techniques, in Proc. 19X4
Hazardous Material Spills Conf.. Ludwigson, J.. Ed.. Government Institutes. Inc.. Rockville. Md.. 1984.
98.
270. Fogel, S., persona! communication.
271. Wilson, J., unpublished data.
272. Henson, M., personal communication.
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APPENDIX D
SUPPLEMENTARY MATERIAL FOR ONSITE BIOREMEDIATION
OF WOOD PRESERVING CONTAMINANTS IN SOILS
Dr. Ronald C. Sims, EPA-RSKERL, Ada, Oklahoma
(Utah State University)
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TECHNICAL REPORT DATA
(Heat* read inttruetions on the rtvtrte before completing)
1. REPORT NO. a.
EPA/600/2-88/055
3. RECIPIENT'S ACCESSION NO.
PB89 1 0 9 9 2 0 /AS
4. TITLE ANO SUrriTLE
CHARACTERIZATION AND LABORATORY SOIL TREATABILITY
STUDIES FOR CREOSOTE AND PENTACHLOROPHENOL SLUDGES
AND CONTAMINATED SOIL
S. REPORT OATE
September 1988
». PERFORMING ORGANIZATION CODE
H. Borazjani, L.K. McFarland, D.F. Pope
and D.A. Strobel
S. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAM! ANO AODRESS
Mississippi Forest Products Utilization Laboratory-
Mississippi State University-
Mississippi State, US 39762
10. PROGRAM ELEMENT NO.
CBWD1A
1^. dfiNf AAfit/flAANT NO.
CR-811498
12. SPONSORING AGENCY NAME ANO AODRESS
Robert S. Kerr Environmental Research Lab. - Ada, OK
U.S. Environmental Protection Agency
Post Office Box 1198
Ada, OK 74820
13. TYPE OF REPORT ANO PERIOD COVEREO
Rop" *•+¦ fWR7_nA/s^
14. SPONSORING AGENCY CODE
EPA/600/1?
IS. SUPPLEMENTARY NOTES
Project Officer: John E. Matthews, FTS: 743-2333
18"AesfiWrmation is presented from characterization and laboratory treatability phases
of a 3-phase study pertaining to on-site treatability potential of soils containing
hazardous constituents from wood-treatment waste (EPA-K001). Specific information
contained Includes: 1) literature assessment of soil treatability potential for wood
treating chemicals; 2) sludge/soil characterization data for 8 wood treating sites;
and 3) degradatjon/toxicity data for wood treating chemicals 1n soils from 4 sites.
Literature data Indicated that creosote/PCP waste constituents may be treatable in
soil. Each sludge characterized contained the PAH constituents; relative concentratior
of Individual compounds varied among sludges. PCP sludges contained PCP, OCCD, and
traces of hepta/hexa dioxins and corresponding furans.
PAH's with 2 rings generally exhibited half lives < 10 days. Three ring PAH's
generally exhibited longer half lives < 100 days. Four or five ring PAH's exhibited
half lives .> 100 days; in specific cases, some 4 or 5 ring PAH's exhibited half lives
< 10 days. PCP half lives varied from 20 to > 1000 days in different soils. PCP was
transformed slowly in soils with no prior long term exposure to PCP. Microbial plate
counts used in this study did not appear to be closely related to transformation rates
17. KEY WORDS ANO DOCUMENT ANALYSIS
a. DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSati Field/Group
18. DISTRIBUTION STATEMENT
RELEASE TO THE PUBLIC.
19. SECURITY CLASS iTIut Report)
ITMnT.A.^TTTVn
21. NO. OF PAGES
HI
20. SECURITY CLASS I This pagei
unclassified.
22. PRICE
EPA Farm 2220-1 (*•». 4-77) previous COi TION i* otiotin^
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57
SECTION 4
EXPERIMENTAL SECTION
INTRODUCTION
This project was started on February 15, 1985 and consists of three
phases: Phase I--site selection and characterization studies for
defining selected soil and sludge characteristics at eight wood-treating
sites; Phase II--laboratory treatability studies for determining rates
of microbiological degradation or other transformation processes, soil
transport properties of creosote and pentachlorophenol, and toxicity of
the water-soluble fraction of waste soil mixtures; and Phase III—a
field evaluation study at one of the eight wood-treating sites. The
following is a summary of the experimental methods for the
characterization phase and the laboratory treatability phase for four of
the eight sites. A detailed methodology 1s presented in Appendix A.
SITE SELECTION CRITERIA
Eight wood-treating sites were selected in the southeastern United
States, each having a different soil type. At each plant a site was
selected approximately 1/2 to 1 acre in area which could be used for the
field evaluation. The sites were selected using the following criteria:
1. Site must have a source of sludges, preferably a separate
source for PCP and creosote sludges.
2. Site should have low level exposure to PCP and creosote so that
an acclimated bacteria population 1s available, but there
should not be high levels of contamination within or below the
treatment zone.
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58
3. There must be a method of collecting and disposing of run-off
water from the site.
SITE, SOIL, AND SLUDGE CHARACTERIZATION
During the first visit to each plant site, one or more potential
demonstration sites were selected and composite soil samples were
collected. Soil samples were collected at 0-6 Inches and 6-12 Inches
and subsequently analyzed for creosote and pentachlorophenol. Based on
the chemical analysis, microbial population, and initial observations,
one potential field evaluation site was selected at each plant location.
A second visit to each site was made in order to do a thorough site
assessment as well as more complete chemical and microbiological
characterization of the site soil. Soil samples were collected using a
systematic sampling plan; The exact number of samples depended on the
size of the area. . The samples were then composited and analyzed.
A third visit was made to each site for soil evaluation. Soil
profiles were examined at each site in freshly excavated pits and they
were described and sampled using standard methods (Soil Survey Staff,
1951). Soil morphological descriptions included horizonation, Munsell
color, texture, horizon boundaries, consistency, coarse fragments, root
distribution, concretions and pedologlcal features. Each horizon was
sampled for laboratory analyses. Detailed analytical procedures used at
each site are given in Appendix A.
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59
LABORATORY TREATABILITY STUOIES
Transformation/Degradation Using a Standard Creosote/PCP Mixture;
Experiment I
Phase II involved laboratory treatability studies for determining
rates of degradation/transformation, soil transport properties of
creosote and pentachlorophenol, and toxicity of the water-soluble
fraction of waste soil mixtures. As a preliminary experiment to
determine possible loading rates, sampling times, refine experimental
techniques, and compare results 1n different soils using a common waste,
an Initial set of degradation/transformation experiments was conducted
by applying, at IX of the soil dry weight, a mixture of technical-grade
pentachlorophenol and creosote at 200 and 2000 ppm, respectively
(standard mixture) to a sample of each site's soil. Samples of each
soil were taken at 0, 30, 60, and 90 days for chemical and
microbiological analysis.
Transformation/Degradation of Site Specific Sludges; Experiment II
The second part of the laboratory degradation studies involved
studying the kinetic rates using soil and sludges from the same site.
The objective was to assess the feasibility of land treatment of the
sludge present at a site in the soil at that site. Three sludge loading
rates were tested, and the study was replicated three times. Soil
samples were taken at 0, 30, 60, and 90 days for chemical and
microbiological analysis.
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60
SECTION 5
RESULTS AND DISCUSSION
SITE AND SOIL CHARACTERIZATION
The eight sites investigated represented very diverse soil,
geologic, climatic, and environmental conditions. The sites ranged from
near sea level in 6ulfport, Mississippi and Wilmington, North Carolina
to elevations above 1000 feet at Atlanta, Georgia. The study areas were
located in six Major Land Resource Areas (MLRA) of the United States as
shown in Table 14.
The sites encompassed several geomorphic landforms ranging from
fluvial terraces to upland ridges. Soil parent materials
varied from sandy Coastal Plain sediments and silty Peoria loess to
granite gneiss residuum as shown in Table 15.
A brief discussion of the pertinent characteristics of each site 1s
presented in the following paragraphs.
Grenada, MS—Moderately well-drained Loring soil comprises the
site. Silt content exceeded 70% in the surface horizons and increased
at deeper depths in the lower sola. Maximum clay content occurred in the
Btxl horizon at depths of 16-26 inches. The fragipan horizons (Btxl,
Btx2) had very low hydraulic conductivity and tended to perch water
above the fragipan during the wetter winter and spring months. These
layers greatly reduced downward leacheate movement. The surface horizon
was strongly acid and pH levels increased with depth. Acidity (H)
decreased in the deeper horizons as pH increases. Exchangeable A1
levels reached a maximum level in the Btxl horizon at depths of 16-26
inches, comprising 30.7% of the cation exchange capacity. Mg and Ca
-------
Table 14. Site location in Major Land Resource Areas.
Site
MIRA
Grenada, MS
134 - Southern MS Valley Silty Uplands
Gulfport, MS
152A - Eastern Gulf Coast Flatwoods
Wiggins, MS
133A - Southern Coastal Plain
Columbus, MS
133A - Southern Coastal Plain
Atlanta, GA
136 - Southern Piedmont
Wilmington, NC
153A - Atlantic Coast Flatwoods
Meridian, MS
133A - Southern Coastal Plain
Chattanooga, TN
128 - Southern Appalachian Ridges and Valleys
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62
Table 15. Overall field evaluation site soil composition.
Site
Soil
Sanda
Silt3
Claya
Grenada, MS
6renada silt loam
16.06
70.17
13,77
Gulfport, MS
Smithton
57.04
28.88
14.08
Wiggins, MS
McLaurin sandy loam
72.55
24.16
3.29
Columbus, MS
Latonia loamy sand
80.03
16.42
3.55
Atlanta, GA
Urban land
mm
—
mm
Wilmington, NC
Urban land
91.5
6.0
2.5
Meridian, MS
Stough sandy loam
60.2
31.4
8.4
Chattanooga, TN
Urban land complex
13.01
46.77
40.22
aThese samples were taken from the surface to a depth of 5 inches.
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63
were the dominant metallic cations with levels increasing with depth.
Electrical conductivity levels were low indicating no salt toxicity
problems. Maximum total S content of 0.018% occurred 1n the surface
horizon. Water holding capacity was high in the surface horizon. The
clay fraction of the surface soil was dominated with kaolinite and mica
(ilUte) with 111 ite increasing in the subsoil and kaolinite decreasing.
Sulfport, MS—The site had 7 to 8 inches of mixed fill-soil
overlying a poorly drained Smlthton sandy loam soil. The site had slow
runoff and subsoils that were moderately slow permeable subsoils.
Maximum clay content (24.6X) occurred 1n the fill-soil capping and
abruptly decreased to 3% in the subjacent, original surface horizon.
Calcareous shells were common 1n the fill-soil, and were also mixed to
the 7- to 12-inch layer. The calcareous materials were part of the
fill-soil placed over the natural soil. The water table is near the
surface during the wetter months. The added calcareous materials
resulted in high levels of exchangeable Ca to depths of 38 inches which
produced high base saturation levels and high pH levels (6.3 to 7.7).
Low levels of Na were detected. Electrical conductivity values
reflected the influence of the calcareous materials. Cation exchange
capacity values were less than 6 me/100 g below depths of 12 inches.
Total S levels were low with a maximum of 0.018% occurring in the A
horizon at depths of 7 to 12 inches. The soil had relatively high
available water holding capacity. Kaolinite was the dominant clay
mineral in the surface horizon and subsoil. The fill-soil capping
contained small amounts of smectite.
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64
Wiggins, MS—Deep, well-drained McLaurin sandy loam soils dominated
this site. These soils had slow to medium runoff and moderate
permeability. The soil was very strongly to strongly acid throughout
the 60-inch solum. The soil was poly-genetic with two distinct clay
maxima in the argillic horizon. Maximum clay content of 36.7X occurred
at depths of 39 to 60 inches. The soil had low base saturation and
cation exchange capacity, and electrical conductivity values reflected
the low soluble salt content. The surface horizon had a high saturated
conductivity value with variations in the subsoil due to the two clay
maxima. The soil had low S contents with a maximum value occurring in
the 39- to 60-1nch horizon. The subsoil had low water holding capacity.
Kaollnite was the dominant clay mineral 1n the surface and subsoil with
lesser amounts of vermlculite-chlorlte integrade.
Columbus, MS—A deep, well-drained sandy Latonla soil with
moderately rapid permeable subsoil and slow runoff comprised the study
area. The soil had loamy sand textures to a depth of 40 inches where
gravelly sands occur. A maximum clay content of 7.5% occurred at depths
of 17 to 25 inches. The soil was medium to strongly add throughout the
profile. Higher Ca levels were present in the upper horizons due to
prolonged additions of leacheate from treated-wood products. The soil
had elevated organic matter contents in the surface horizon from
cultural additions which resulted in higher cation exchange capacity.
Electrical conductivity values reflected the low soluble-salt content,
with the highest levels in the surface horizon due to the added
leacheate. Low contents of Mg, K, and Na were present throughout the
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65
profile. The highest S content of 0.095 occurred in the surface
horizon. Kaollnite was the dominant clay mineral in the surface and
subsoil horizons.
Atlanta, GA—The site had been truncated and the soil solum removed
by cutting which exposed the subsoil C horizon and weathered saprolite
parent material. The surface had accumulated organic carbon from
additions of material 1n the pole yard. The partially weathered
saprolite had high bulk density values and was firm 1n place, but tends
to be loose when disturbed. The saprolite had low saturated hydraulic
conductivity. The loose upper horizon had sandy loam textures. Clay
content was less than 6% in the material sampled. The material was very
strongly acid in the lower depths. Calcium is the dominant exchangeable
cation. Cation exchange capacities are very low reflecting the low clay
content. Kaolinite was the dominant clay mineral.
Wilmington, NC--The site was comprised of made land with 1 to 3
feet of sandy fill material over poorly drained sediments. The water
table appeared to be affected by tidal fluctuations of the adjacent Cape
Fear River. A. water table at 21 inches and saturated sands below
limited the depth of sampling. The soil had sand textures throughout
the profile with a maximum clay content of 2.5X occurring 1n the surface
horizon. The profile was moderately alkaline to neutral. Organic
carbon had accumulated in the surface horizons from added materials.
Calcium was the dominant exchangeable cation with low contents of other
bases. Cation exchange capacity was essentially due to the added humus
material, and value were less than 1 me/100 g at depths below 10 inches.
Higher electrical conductivities occur 1n the upper layers analyzed due
to added materials. The soil material haa extremely high permeability
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66
with saturated hydraulic values of 34 inches/hr at depths below 10
inches. The material had low water-holding capacity below the surface.
A complex mineral suite comprised the small clay fraction with kaolinite
the dominant mineral.
Meridian, MS--Somewhat poorly drained Stough soils comprised the
study area. These soils had slow runoff, moderately slow permeability,
and were formed in thick beds of f1uvial sediments. The soil had sandy
loam upper horizons and loamy textured subsoils. Maximum clay content
of 21.8% occurred at depths of 23 to 35 inches. Slightly firm, brittle
horizons occurred at depths below 15 inches which tend to perch water
during wet periods. The soil was strongly to very strongly acid
throughout the profile. Acidity and calcium dominated the cation
exchange complex. Kaolinite dominated the clay fraction of the surface
and subsoil.
Chattanooga, TN—The site was located in a soil area mapped as
urban land. The surface layer (0-4 inches) was a compacted mixture of
limestone gravel and silty clay. The subsoil was a thick argillie
horizon of silty clay and silty clay loam textures with slightly firm
consistency. The surface horizon was mildly alkaline due to the
limestone gravel additions, and the underlying profile was very strongly
acid. The site was well-drained with no evidence of free water at
depths of 90 inches. The soil had high bulk density and low saturated
hydraulic conductivity. Available water-holding capacity was low.
Maximum clay content of 49.2% occurred at depths of 38 to 44 inches.
Exchangeable Ca, base saturation, and electrical conductivity were
influenced by the limestone gravel in the surface horizon. Exchangeable
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67
aluminum comprised a significant proportion of the cation exchange
complex in the subsurface horizons. The soil had a complex clay mineral
suite dominated by kaolinite.
The general soil type and the amounts of sand, clay, and silt for
each location are summarized in Table 15.
Chemical Analysis of Wood-Treating Chemicals the Soil,
One of the main concerns In selecting a field evaluation site for
this study was levels of Background chemicals 1n the soil. Chemical
analyses of the amount of pentachlorophenol, creosote, and
octachlorod1benzo-p-dioxin at various depths are summarized 1n Tables
16-18. Grenada, Gulfport, and Columbus had no detectable levels of
pentachlorophenol below 10 Inches. The Wiggins site had
pentachlorophenol down to 20 Inches, while the other sites had
detectable levels down to 60 Inches or to ground water. The detection
limit for pentachlorophenol 1n soil was 27 ppb. Soil from Grenada,
Gulfport. Atlanta, Meridian. Wiggins, and Chattanooga had no detectable
levels of PAH's below 10 Inches while those from Columbus and Wilmington
had PAH's down to 20 Inches or deeper. 0ctachlorod1benM-p-d1ox1n
levels at the soil surface (0-6 Inches) varied from none detected to
2.38 ppm (Table 18). The soil and sludge detection limits for the
Individual PAH's, 0C00, and for PCP are given 1n Appendix A.
Microbial plate counts for soils at each .He Te presented 1n
Table 19. Counts of bacteria were don. on potato dextrose agar (PDA),
•lone, or with various additives. This data provides an approximate
lumber of total soil bacteria and fungi, as well as the number of soil
bacteria that can tolerate or utilize creosote or pentachlorophenol.
-------
Table 16. Soil concentration of PCP at the proposed field evaluation sites.
Depth Grenada Gulfport Wiggins Columbus Atlanta Wilmington Meridian Chattanooga
(inches) Pentachlorophenol concentration (ppm in soil)
0-10
NDa
0.112
0.389
NO
20.64
1.418
0.129k
0.288b
10-20
NO
ND
0.017
ND
0.088
0.218
0.090
0.099
20-30
NO
NO
ND
NO
0.130
0.209c
0.096
0.090
30-40
ND
ND
ND
ND
0.147
—
0.104
0.074
40-50
NO
ND
ND
ND
0.319
—
0.053
0.057
50-60
NO
NO
NO
ND
MM
MM
aND * Not Detected.
bThis value is the average of 4 values, two samples were taken at 0-6 inches, and two were taken
from 6-10 Inches.
cThe maximum depth that soil could be collected at this site was 20 to 23 inches due to the high
levels of ground water.
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Table 17. Soil concentration of PAH's at the proposed field evaluation sites.
Depth Grenada Gulfport Wiggins Columbus Atlanta Wilmington Meridian Chattanooga
(inches) Total polycyclic aromatics in soil3 (ppm)
0-10
NDb
1.78
0.33
195.9 c
110.81d
193.3
ND
121.769
10-20
ND
NU
ND
27.45e
ND'
ND
40.55.
ND
ND
20-30
NO
ND
ND
ND
43.94
ND
ND
30-40
NO
NO
ND
ND
NO
—
ND
ND
40-50
ND
ND
NO
ND
ND
—
NO
NO
50-60
NO
ND
ND
ND
ND
"
ND
MM
aThe total concentration of 16 polycyclic aromatic hydrocarbons (naphthalene, 2-methylnaphthalene,
1-methy1naphthalene, biphenyl, acenaphthylene, acenaphthene, dibenzofuran, fluorene,
phenanthrene, anthracene, carbazole, fluoranthene, pyrene, 1,2-benzanthracene, chrysene,
benzo(a)pyrene, benzo(ghi)pery1ene.
"Normal 16 PAH compounds were detectable in the soil sample.
^Sample taken between 0 to 6 inches.
"Sample taken between 6 to 16 inches.
^Sample taken between 16 to 26 inches.
'Analysis done between 20 to 23 inches (ground water was at 23 inches and below).
^Average value of 4 samples (2 samples taken from 0 to 6 inches and 2 samples taken from 6 to 10
inches).
*%) = Not Detected.
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70
Table 18. Soil concentration of octachlorodibenzo-p-dioxin at the
proposed land treatment sites (0 to 6 inches).
Octachlorodibenzo-p-dioxin
(ppm)a
Grenada
Gulfport
Wiggins
Columbus
Atlanta
Wilmington
Meridian
Chattanooga
aThese samples represent soil at 0 to 6 inches and are the average of a
minimum of three replicates standard deviation.
bN0 » Not Detected.
0.12 + 0.22
0.37 " 0.24
0.077 + 0.19
0.034 + 0.22
2.13 +.0.34
f#
NO
0.36 + 0.57
-------
Table 19. Microbial plate counts at proposed field evaluation sites.a
Types of media (counts/gram)
PDA
POAA
PDA ~
PDA +
PDA +
Soil
creosote
penta-
creosote ft
Site
Depth
chlorophenol
pentach1orophenol
Atlanta
0-6"
900,000
60,000
700,000
450,000
450,000
Chattanooga
0-6"
473,000
23,000
203,000
30,000
-6,000
Columbus
0-6"
290,000
120,000
220,000
20,000
io.ooo
Grenada
0-6"
1,000,000
180,000
600,000
110,000
125,000
Gulfport
0-6"
1,B00,000
100,000
1,000,000
90,000
100,000
Meridian
0-6"
1,683,000
141,000
1,600,000
466,000
250,000
Wiggins
0-6"
1,200,000
80,000
500,000
60,000
80,000
Wilmington
0-6"
763,000
40,000
523,000
166,000
66,000
dEach figure represents an average of three replications. The values were obtained by
adding 0.1 «g of soil diluted with 9.9 mg of sterile soil to each plate.
Table 20. Nitrogen and phosphorous at the eight selected sites.a
Grenada
Gulfport
Uiggins
Columbus
Atlanta
Wilmington
Meridian
Chattanooga
- ppm —
Total Nitrogen
1709
1999
1150
1598
1501
1231
2990
2000
Total Phosphorous
310
292
255
338
254
597
315
237
aBased on dry weight.
-------
72
The nitrogen and phosphorous contents for the soil at each site are
given 1n Table 20.
Sludge Characterization
Each plant site had different types of sludges. Six of the plants
had open lagoons of creosote and/or pentachlorophenol; one site had
three lagoons which were segregated into pentachlorophenol,
pentachlorophenol in a heavy oil, and creosote; two other plants had no
lagoons but had areas of dried sludge and contaminated soil (see Table
21).
The water content, total organic and inorganic materials, pH, and
total organic carbon are summarized in Table 22. Water contents of
these samples varied from 26.6 to 74.58%. The total organic material
ranged from 8.96 to 68.OX. The pH varied from 3.00 to 7.20. The more
acidic sites contained large amounts of PCP. The total organic carbon
varied from 4.02 to 49.79%. The wide variation 1n inorganic sol Ids is
not surprising since these sludges are stored in large open lagoons.
The. pH 1s related to the concentration of PCP in sludge and probably 1s
also affected by the soil pH. The high levels of organic materials are
mainly the heavy oils used to dissolve PCP for treating wood and the
aliphatic fraction found in creosote.
Total phenolics, oil and grease, nitrogen phosphorus, and chloride
content of the sludges are summarized in Table 23. Concentrations of
pentachlorophenol and polycyclic aromatic hydrocarbons in the sludges
are given in Table 24. A more detailed list of the individual
concentration of PAH's in each sludge is given 1n Table 25.
-------
73
Table 21. Characteristics of the eight sites used in this study.
Site
location
Size &
age of plant
Preservative
used
Number & type
of lagoons
Grenada, MS
100 acres
78 years old
Both penta-
chloropenol
and creosote
Lagoons are closed;
contaminated soil
and sludge are
present
Gulfport, MS
100 acres
80 years old
Both penta-
chlorophenol
(65%) and
creosote (35%)
Large lagoon of
mixed preservatives
and contaminated
soil
Wiggins, MS
100 acres
15 years old
Both penta-
chlorophenol
(60%) and
creosote (40%)
Individual lagoons of
1) pentachlorophenol,
2) pentachlorophenol
in heavy oil, and
3) creosote
Columbus, MS
mm
Creosote
(100%)
Contaminated soil and
lagoon
Atlanta, GA
15 acres
63 years old
Both penta-
chlorophenol
(80%) and
creosote (20%)
Contaminated soil and
lagoon
Wilmington, NCa
Both penta-
chlorophenol
and creosote
Lagoons are closed
but contaminated soil
1s available
Meridian, MS
125 acres
61 years old
Both penta-
chlorophenol
(25%) and
creosote (75%)
Large lagoon and con-
taminated soil
available
Chattanooga, TN
76 acres
62 years old
Creosote (100%)
Enclosed lagoons and
contaminated soil
aThis site has been an active land farming site for 1 1/2 years.
-------
Table 22. Composition of the sludges.4
Total
Total
Water
organic
Inorganic
organic
content
materials
solids
PH
carbon
(X)
(*)
(*>
(*)
Grenada
74.58
24.31
1.11
6.30
7.37
Gulfport .
30.62
68.00
1.38
4.80
22.50
Wiggins #1
36.07
40.58
23.35
3.00
37.85
Wiggins #2^
31.56
26.02
42.42
3.50
49.45
Wiggins #3d
36.52
27.80
35.68
5.70
36.03
Columbus
34.44
61.11
4.45
5.90
49.79
Atlanta
69.10
23.76
7.14
5.00
25.33
Wilmington
26.60
8.96
64.44
7.20
4.02
Meridian
48.27
50.00
1.73
4.00
31.96
Chattanooga
67.35
15.74
16.91
7.10
14.61
Table 23. Chemical composition of the sludges.3
Total
Inorganic
Oil and
chloride
Site
phenolics
grease
Nitrogen
Phosphorous
content
(X)
(%)
(ppm)
(ppm)
(ppm)
Grenada
.0041
9.74
7562
236
267
Gulfport .
.0097
44.03
2949
506
440
Wiggins #1°
.0045
15.86
1119
446
361
Wiggins *ZC
.0130
22.57
1141
477
753
Wiggins #3d
.0171
17.90
640
261
825
Columbus
.0224
44.60
2951
270
49
Atlanta
.0120
14.17
1730
316
278
Wilmington
.0007
0.44
1283
435
1138
Meridian
.0114
35.34
3621
213
220
Chattanooga
.0003
3.68
2090
417
28
*A11 data reported on the starting weight of sludge.
°lagoon contains mainly pentachlorophenol.
.Lagoon contains mainly pentachlorophenol in a heavy oil.
Lagoon contains mainly creosote.
-------
75
Table 24. Concentration of PCP and total PAH's in each sludge sample.3
Octachloro-
Polycyclic aromatic
hydrocarbons0
dibenzo-p-
Site
Pentachlorophenol
dioxin
(ppm)
(ppm)
(ppm)
Grenada
6,699
96,078
23
Gulfport
5,656
101,023
215
Wiggins #1
29,022
20,463
114
Wiggins #2
30,060
47,075
125
Wiggins #3
1,893
114,127
21
Columbus
NDC
475,372
ND
Atlanta
51,974
119,546
160
Wilmington
NO
10,007
NO
Meridian
13,891
119,124
160
Chattanooga
ND
72,346
NO
aThese values are the means of two replicates and are determined on a
dry basis. Ml were determined by capillary column gas
chromatography.
^Total of the 17 major polycyclic aromatic hydrocarbons found in
creosote.
CND ¦ Not detected. See Appendix A for detection limits.
-------
B ^
Table 25. Concentration of creosote and PCP In sludges from the selected sites (fig/g dry weight).
2Mn
lMn
B1
Ac Ace
01
F1
Ph
An
Ca Flu
Py
1.28
Ch
Bz
Bzg
Grenada
67000
24150
13250
5850
5250
21500
17000
18000
43000
15000
3450
27000
19500
3250
5850
3600
5050
Gulfport
13500
14000
7450
3000
2635
10150
9600
10250
30000
7200
2100
17000
12500
2050
3650
1050
N0b
Wiggins 11
3400
2450
1400
535
215
15S0
1300
1750
5000
2550
570
2150
1500
18S
495
75
NO
Wiggins #2
10200
7450
4000
1900
1050
5550
6050
7450
21000
8150
2650
11500
7500
1300
2400
355
NO
Ulgglns #3
17500
12000
6350
3500
2000
13000
11500
14000
34000
14500
4250
22500
19000
3850
6000
580
NO
Columbus
70500
29500
16500
10500
7650
31000
32500
34000
53000
23000
12500
49500
38000
12500
17000
3500
6850
Atlanta
39400
23000
11500
6600
2800
16500
16000
18000
45000
24500
9550
23000
15500
3400
5800
1100
8050
Wilmington
350
330
185
NO
NO
400
425
585
1550
1525
190
840
430
150
150
NO
NO
Meridian
16500
5350
2700
1650
1800
5150
6850
7350
29500
6550
2050
20000
11700
2200
4800
1350
550
Chattanooga
1200
815
585
445
NO
1230
1150
1415
5400
2200
870
3550
2100
200
200
NO
NO
N " Naphthalene
2Mn " 2-Methylnaphthalene
lMn - 1-Nethylnaphthalene
B1 " Blphenyl
Ac ¦ Acenaphthylene
Ace - Acenaphthene
01 " Olbenzofuran
F1 - Fluorene
Ph ¦ Phenanthrene
An - Anthracene
Ca » Carbazole
Flu " Fluoranthene
Py ¦ Pyrene
1,2B " 1,2-Benzanthracene
Ch ¦ Chrysene
Bz " Benzo(a)pyrene
Bzg ¦ Benzo(gh1)perylene
Pen tach1oropheno1
aThese values were obtained by 6C/MS.
bN0 » Hot detected.
--j
cn
-------
77
The results in Table 24 are obtained by capillary column gas
chromatography while the results in Table 25 are obtained using GC/MS.
Gas chromatography/mass spectrometry was also used to identify some of
the minor constituents in the sludges. The results are summarized in
Table 26.
The trace metal content of the sludges are summarized in Table 27.
The most common metals found at most wood-treating plants are mixtures
of copper chromium and arsenic salts. None of the sludges had high
levels of chromium and arsenic. None of the sites had used fire
retardant treatments (ZnC^).
LABORATORY TRANSFORMATION/DEGRADATION STUDIES
Transformation/Degradation Using a Standard Creosote/PCP Mixture:
Experiment"!
The results of Experiment I are shown in Figures 4 and 5 for
the microbiological data, and Tables 28 through 36 for transformation/
degradation rates.
Gulfport soil was able to transform all the PAH's analyzed, with
only two (pyrene and benzo-a-pyrene) having relatively slow breakdown
rates. Columbus soil was able to transform all PAH's but anthracene,
though at somewhat slower rates than Gulfport for most PAH's. Gulfport
and Columbus developed higher levels of acclimated organisms than the
other sites, possibly accounting for the better transformation. Soil
from the other sites transformed most of the lower molecular weight
PAH's readily. Many of the higher molecular weight PAH's (fluoranthene,
pyrene, l,2-ben2anthracene, chrysene, and benzo-a-pyrene) tended to
transform slowly if at all. Pyrene and fluoranthene were perhaps the
most recalcitrant.
-------
Table 26. Minor components present In sludge.
Site location and number of Isomers
Molecular weight
Possible co«pounds
Gr
Gp
Will
M1I2
3U1I3
Co
At
Ua Mr Ch
156
d1*ethy1naphthalene. ethylnaphtha1ene
2
3
2
3
2
1
3
168
aethyldlpheayl, ae thy 1acenaphthene,
dlphenylaethane
••
••
1
170
trlaethylnaphthalene
—
1
2
—
182
dlaethylbtphenyl, ethylb(phenyl,
¦ethyldlbenzofuran, dtaethylacenaphthene
2
2
1
184
dlbenzothlopene, tetraoethylnaphthalene
1
—
—
--
—
1
1
1
192
¦ethy1phenan threne, me thy1an thracene,
phenylIndene
3
3
3
2
3
3
3
204
phenylnaphthalene. vlnylphenanthrene.
vinylanthracene
••
••
1
1
'*
1
216
¦ethylfluoranthene, *ethylpyrene,
benzofluorene
2
2
••
1
1
2
2
2
218
benzonaphthofuran
1
1
—
1
--
1
1
1
226
benzo(gh1)fluoranthene, cyclopenta(cd)
pyrene
••
••
""
1
1 ""
252
benzo(k)fluoranthene, perylene, benzo(e)
pyrene. benzo(abj)fluoranthene, and
others
1
1
2
2
230
tetrachlorophenol
••
••
1
1
1
1
At - Atlanta, GA Gp • Gulfport, MS
Ch - Chattanooga, TN Mr • Meridian, MS
Co ¦ Coluabus, HS VI • Wiggins, MS
6r - Grenada, MS W» - Wilatngton, NC
-------
Table 27. Concentration of metals In each sludge simple.
Site
Arsenic
Antlaony
Barton
Serylitw
CadatuM
Chroaiua
Cobalt
Lead
Mercury
Nickel
Selenlua
Vanadlu*
Mg/g
Vg/g
Jjg/g
lig/g
Mg/g
M fl'9
pg/g
Mg/g
pg/g
Mg/g
Mg/g
119/9
Atlanta. M
<.715
<1.50
<0.10
<0.100
<0.200
35.14
0.38
<2.00
0.012
5.82
<0.500
1.78
Chattanooga,
TN
<0.500
<1.50
3.32
1.792
<0.200
26.48
<0.30
<2.00
0.008
27.26
0.612
3.64
Coluritus, KS
<0.500
<1.50
<0.10
<0.100
0.251
13.11
<0.30
12.43
<0.001
14.97
<0.500
<0.50
Grenada. HS
<0.S00
<1.50
<0.10
<0.100
<0.200
5.85
0.35
<2.00
<0.001
7.19
<0.500
<0.50
Gulfport, NS
0.647
<1.50
1.35
0.281
0.143
6.64
<0.30
<2.00
0.003
1.05
<0.500
4.87
Meridian. NS
<0.500
<1.50
<0.10
<0.100
0.160
1.16
<0.30
8.17
0.002
0.30
0.529
1.51
Utlmlngton,
NC
2.491
<1.560
1.83
0.823
<0.200
20.60
<0.30
<2.00
0.003
7.66
<0.500
6.79
Wiggins. MS
11
0.562
<1.50
4.05
0.521
<0.200
6.65
5.84
<2.00
<0.001
4.85
<0.500
1.48
Vlgjlns, MS
12
<0.500
<1.50
0.14
0.493
<0.200
8.39
0.85
<2.00
<0.001
10.91
<0.500
<0.50
Wiggins, MS
13
<0.500
<1.50
<0.10
0.384
<0.200
25.34
2.32
<2.00
<0.001
17.00
<0.500
2.02
U) Concentration of Mtals was determined by digestion Method (302E, APHA Standard HTHDS, 16th Edition, pp. 148-149). and Inductively Coupled argon
Plasm spectroscopy (ICP).
lO
-------
30
1% Loading
1771 o rm so rn «o
0% Loading
x«-|
U -
U-
.14-
22 o O * XZZk «o S£3 90 EES 120 EH 1*>
Figure 4. Bacteria counts from all eight sites at IS and OX loading
rates after the final addition of the standard mixture.
Total bacteria counts on PDA media.
-------
81
1% Loading
223 o E33 » sttts to ED * EES 1»
100
0% Loading
ea o ks
M tM| HI 0»
E23 «0 S3 *> ESS '»
figure 5. Acclimated bacteria counts from all tight sites at IS and
OS loading rates after the final addition of the standard
mixture.
Bacteria acclimated to both PCP and creosote.
-------
Table 28. Kinetic data for PAH degradation/transformation in
Gulfport soils.
Loading
K
T 1/2
Compounds
Dry Wt.
(*)
(day-1)
(days)
Naphthalene
1.0
-0.193
4
2-Methylnaphthalene
1.0
-0.190
4
1-Methylnaphthalene
1.0
-0.183
4
Biphenyl
1.0
-0.179
4
Acenaphthylene
1.0
-0.170
4
Acenaphthene
1.0
-0.200
3
Dibenzofuran
1.0
-0.192
4
Fluorene
1.0
-0.192
4
Phenanthrene
1.0
-0.203
3
Anthracene
1.0
-0.179
4
Carbazole
1.0
-0.184
4
Fluoranthene
1.0
-0.024
29
Pyrene
1.0
-0.001
1155
1,2 Benzanthracene
1.0
-0.194
4
Chrysene
1.0
-0.189
4
Benzo-a-pyrene
1.0
-0.002
365
Benzo-ghi-perylene
1.0
-0.174
4
-------
83
Table 29. Kinetic data for PAH degradation/transformation in
Columbus soils.
Loading K T
Compounds Dry Wt. (day-1) ( ys)
(X)
Naphthalene 1.0 "2* ma \
2-Methylnaphthalene 1.0 n 2
1-Methylnaphthalene 1.0 ")(•;**£
Biphenjl 1.0 -0-025 «
Acenaphthylene 1.0 "'•„)? cQ
Acenapnthene 1.0 "«•«« ??
Dlbenzofuran 1.0
Fluorene 1.0 "• n
Phenanthrene 1.0 NT®
-0.009 81
Anthracene 1.0
Carbazole 1.0 59
Fluoranthene 1.0 5*2.? 53
Pyrene 1.0 J7
1»2 Benzanthracene 1.0 n'niA 49
Chrysene 1.0 82
Benzo-a-pyrene 1.0 «"?#?
-------
Table 30. Kinetic data for PAH degradation/transformation in
Grenada soils.
Loading
K
T 1/2
Compounds
Dry Wt.
(day-1)
(days)
(X)
Naphthalene
1.0
-0.191
4
2-Methylnaphthalene
1.0
-0.189
4
1-Methyl naphtha1ene
1.0
-0.181
4
Biphenyl
1.0
-0.178
4
Acenaphthylene
1.0
-0.235
3
Acenaphthene
1.0
-0.202
3
Dibenzofuran
1.0
-0.255
3
Fluorene
1.0
-0.258
3
Phenanthrene
1.0
-0.257
3
Anthracene
1.0
-0.241
3
Carbazole
1.0
-0.056
12
Fluoranthene
1.0
NTa
NT
Pyrene
1.0
-0.002
289
1,2 Benzanthracene
1.0
NT
NT
Chrysene
1.0
NT
NT
Benzo-a-pyrene
1.0
-0.006
116
Benzo-gh i-pery1ene
1.0
-0.166
4
aNT * no transformation observed.
-------
85
Table 31. Kinetic data for PAH degradation/transformation in
Chattanooga soils.
Loading K L1/2i
Compounds Dry Wt. (day-1) (daysj
(X)
Naphthalene 1.0
2-Methylnaphthalene 1.0
1-Methylnaphthalene 1.0
Biphenyl 1.0
Acenaphthylene 1.0
Acenaphthene 1.0
Dibenzofuran 1.0
Fluorene 1.0
Phenanthrene 1.0
Anthracene 1.0
Carbazole 1.0
Fluoranthene 1.0
Pyrene 1.0
1,2 Benzanthracene 1.0
Chrysene 1.0
Benzo-a-pyrene 1.0
Benzo-ghi-perylene 1.0
-0.132
5
-0.193
4
-0.187
4
-0.181
4
-0.009
77
-0.010
72
-0.013
52
-0.015
47
-o.ou
63
-0.008
91
NTa
NT
-0.001
990
NT
NT
-0.002
3655
NT
NT
NT
NT
-0.008
84
aNT » no transformation observed.
-------
86
Table 32. Kinetic data for PAH degradation/transformation in
Wilmington soils.
Loading K T 1/2
Compounds Dry Wt. (day-1) (days)
(X)
Naphthalene
1.0
-0.193
4
2-Methylnaphthalene
1.0
-0.196
4
1-Methylnaphthalene
1.0
-0.188
4
Bi phenyl
1.0
-0.185
4
Acenaphthylene
1.0
-0.186
4
Acenaphthene
1.0
-0.013
52
Dibenzofuran
1.0
-0.137
5
Fluorene
1.0
-0.009
79
Phenanthrene
1.0
-0.010
68
Anthracene
1.0
NTa
NT
Carbazole
1.0
-0.180
4
Fluoranthene
1.0
-0.004
189
Pyrene
1.0
-0.001
1085
1,2 Benzanthracene
1.0
NT
NT
Chrysene
1.0
-0.004
158
Benzo-a-pyrene
1.0
-0.180
4
Benzo-ghi-perylene
1.0
-0.114
6
aNT ¦ no transformation observed.
-------
87
Table 33. Kinetic data for PAH degradation/transformation in
Meridian soils.
(*)
Loading K Ll/2,
Compounds Dry Wt. (day-1) (days)
Naphthalene 1.0
2-Methylnaphthalene 1.0
1-Methylnaphthalene 1.0
Biphenyl 1.0
Acenaphthylene 1.0
Acenaphthene 1.0
Dibenzofuran 1.0
Fluorene 1.0
Phenanthrene 1.0
Anthracene 1.0
Carbazole 1.0
Fluorantbene 1.0
Pyrene 1.0
1,2 Benzanthracene 1.0
Chrysene 1.0
Benzo-a-pyrene 1.0
Benzo-ghi-perylene 1.0
-0.185
4
-0.186
4
-0.179
4
-0.186
4
-0.174
4
-0.255
3
-0.262
3
-0.258
3
-0.217
ND
3
NO
-0.177
NTb
4
NT
NT
NT
NT
NT
NT
NT
NT
NT
NO
NO
aND ¦ not detected.
bNT « no transformation observed.
-------
Table 34. Kinetic data for PAH degradation/transformation in
Atlanta soils.
Loading
K
T 1/2
Compounds
Dry Wt.
(%)
(day-1)
(days)
Naphthalene
1.0
-0.181
4
2-MethyInaphthalene
1.0
-0.181
4
1-Methylnaphthalene
1.0
-0.178
4
Biphenyl
1.0
-0.171
4
Acenaphthylene
1.0
-0.164
4
Acenaphthene
1.0
-0.020
35
Dibenzofuran
1.0
-0.193
4
Fluorene
1.0
-0.254
3
Phenanthrene
1.0
-0.024
29
Anthracene
1.0
-0.175
4
Carbazole
1.0
-0.174
4
Fluoranthene
1.0
NTa
NT
Pyrene
1.0
NT
NT
1,2 Benzanthracene
1.0
NT
NT
Chrysene
1.0
NT
NT
Benzo-a-pyrene
1.0
NT
NT
Benzo-ghi-perylene
1.0
-0.167
4
aNT » no transformation observed.
-------
89
Table 35. Kinetic data for PAH degradation/transformation in
Wiggins soils.
Loading
K T 1/2
Compounds Dry Wt. (day-1) (days)
(%)
Naphthalene 1.0
2-Methylnaphthalene 1.0
1-Methylnaphthalene 1.0
Biphenyl 1.0
Acenaphthylene 1.0
Acenaphthene 1.0
Dibenzofuran 1.0
Fluorene 1.0
Phenanthrene 1.0
Anthracene 1.0
Carbazole 1.0
Fluoranthene 1.0
Pyrene 1.0
1,2 Benzanthracene 1.0
Chrysene 1.0
Benzo-a-pyrene 1.0
Benzo-ghi-perylene 1.0
-0.318
2
-0.313
2
-0.301
2
-0.294
2
-0.299
2
-0.338
2
-0.319
2
-0.329
2
-0.342
2
-0.309
2
-0.305
2
NTa
NT
NT
NT
-0.006
117
NT
NT
-0.302
2
-0.284
2
aNT ¦ no transformation observed.
-------
90
Table 36. Kinetic data for PCP degradation/transformation
in site soils.
Loading
K
T 1/2
Site
Dry Wt.
(day-1)
(days)
(X)
Gulfport
1.0
-0.0107
64
Grenada
1.0
-0.0024
289
Columbus
1.0
NT®
NT
Atlanta
1.0
NT
NT
Wiggins
1.0
NT
NT
Chattanooga
1.0
-0.0027
259
Wilmington
1.0
-0.0022
320
Meridian
1.0
-0.0009
815
aNT ¦ no transformation observed.
-------
91
PCP transformation occurred in Gulfport, Grenada, Chattanooga,
Wilmington, and Meridian soils. PCP half life was 64 days in Gulfport
soil, but well over 100 days for the other soils. Columbus, Atlanta,
and Wiggins soil exhibited no transformation of PCP.
The results of this preliminary experiment Indicate that all of the
compounds studied can be transformed in soils at practically useful
rates under the appropriate conditions. Microorganism counts of the
type used 1n this experiment do not appear to be extremely accurate
indicators of potential breakdown rates for particular compounds.
However, there 1s some tendency for soils with higher populations of
acclimated microorganisms to transform more of the different PAH s in
creosote sludge at practically useful rates. This might be due to
larger numbers of particular microorganisms or to a more diverse array
of microbial species.
Since some of the soils exhibited no breakdown of particular PAH's,
it would be desirable to test a range of loadings 1n subsequent
experiments to see if lower loading rates might allow enhanced
transformation in these soils.
Transformation/Degradation of Site Specific Sludges.—Experiment II
The results of Experiment II «re shown in Tables 37 through 42
for transformation/degradation kinetic data and Table 43
microbiological data.
... e-im-nar in soils from all four sites
The total PAH breakdown was similar in
. The individual PAH's can be
for similar loading concentrations, ine
with half lives of ten days or less,
divided into three groups; those wltn
, ^ u.mrfred davs or less, and those with half
those with half lives of one hundreo oay
-------
92
Table 37. Kinetic data for PAH degradation/transformation in Columbus soils.
95% Confidence
Interval
Lower
Limit
Upper
Limit
Loading
K
T 1/2
K
T 1/2
<
T Hi
Compounds
Dry Wt.
(day-1)
(days)
(day-1)
(days)
(day-1)
(days)
(*)
Naphthalene
0.33
-0.535
1
-0.573
1
-0.498
1
2-Methylnaphthalene
0.33
-0.536
1
-0.551
1
-0.521
1
1-Methy1naphthalene
0.33
-0.531
1
-0.537
1
-0.524
1
Biphenyl
0.33
-0.513
1
-0.520
1
-0.507
1
Acenaphthylene
0.33
-0.508
1
-0.517
1
-0.498
1
Acenaphthene
0.33
-0.187
4
-0.288
2
-0.086
8
Dibenzofuran
0.33
-0.202
3
-0.242
3
-0.162
4
Fluorene
0.33
-0.204
3
-0.241
3
-0.167
4
Phenanthrene
0.33
-0.039
18
-0.064
11
-0.014
50
Anthracene
0.33
-0.015
46
-0.020
35
-0.010
68
Carbazole
0.33
-0.020
35
-0.024
30
-0.016
43
Fluoranthene
0.33
-0.013
53
-0.024
29
-0.003
248
Pyrene
0.33
-0.003
231
-0.007
100
NTa
NT
1,2 Benzanthracene
0.33
-0.002
347
-0.006
122
NT
NT
Chrysene
0.33
-0.007
102
-0.011
61
-0.002
301
8enzo-a-pyrene
0.33
NTh
NT
NT
NT
NT
NT
Benzo-ghi-perylene
0.33
NO
NO
NO
NO
ND
NO
aNT » no transformation observed.
bNQ « not detected.
-------
93
Table 37. Kinetic data for PAH degradation/transformation in Columbus soils,
(continued)
Compounds
Loading
Dry Wt.
(X)
K
(day-1)
T 1/2
(days)
95% Confidence Interval
Lower Limit
~TVT
K
(day-1)
(days)
Upper Limit
K
(day-1)
TUT"
(days)
Naphthalene . 1.0
2-Methylnaphthalene 1.0
1-Methylnaphthalene 1.0
Bi phenyl 1.0
Acenaphthylene 1.0
Acenaphthene 1.0
Dibenzofuran 1.0
Huorene 1*0
Phenanthrene 1.0
Anthracene 1.0
Carbazole 1.0
Pluoranthene 1.0
Pyrene 1.0
1|2 Benzanthracene 1.0
Chrysene 1.0
Benzo-a-pyrene 1.0
Benzo-ghi-perylene 1.0
-0.049
-0.096
-0.207
-0.149
-0.074
-0.028
-0.325
-0.022
-0.027
NT
-0.009
-0.002
-0.002
-0.001
-0.002
NT
NT
14
7
3
5
9
25
2
31
25
NT
75
289
433
578
365
NT
NT
-0.072
10
-0.025
28
-0.169
4
-0.023
29
-0.252
3
-0.162
4
-0.228
3
-0.070
10.
-0.152
5
NT
NT
-0.041
17
-0.014
50
-0.040
17
-0.025
28
-0.031
22
-0.013
52
-0.041
17
-0.014
50
NT
NT
NT
NT
-0.015
48
-0.004
169
-0.004
165
-0.001
1155
-0.004
187
NT
NT
-0.004
173
NT
NT
-0.004
173
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
-------
94
Table 37. Kinetic data for PAH degradation/transformation 1n Columbus soils,
(continued)
95% Confidence Interval
Lower
Limit
Upper Limit _
Loading
K
T 1/2
K
T 1/2
K
T 1/2
Compounds
Dry Wt.
(X)
(day-1)
(days)
(day-1)
(days)
(day-1)
(days)
Naphthalene
3.0
-0.050
14
-0.066
11
-0.033
21
2-Methy1naphtha1ene
3.0
-0.029
24
-0.037
19
-0.021
33
1-Methy1naphtha1ene
3.0
-0.018
39
-0.024
28
-0.011
61
Biphenyl
3.0
-0.012
57
-0.023
30
-0.001
578
Acenaphthylene
3.0
-0.006
112
-0.008
89
-0.005
147
Acenaphthene
3.0
-0.006
124
-0.007
96
-0.004
169
Dibenzofuran
3.0
-0.005
147
-0.007
99
-0.002
301
Fluorene
3.0
-0.003
224
-0.004
169
-0.002
347
Phenanthrene
3.0
-0.001
578
-0.004
173
NT
NT
Anthracene
3.0
-0.004
173
-0.007
96
-0.001
866
Carbazole
3.0
-0.008
90
-0.011
62
-0.004
169
Fluoranthene
3.0
-0.007
107
-0.010
67
-0.003
267
Pyrene
3.0
-0.007
99
-0.011
62
-0.003
248
1,2 Benzanthracene
3.0
-0.002
315
-0.009
82
NT
NT
Chrysene
3.0
-0.007
98
-0.015
47
NT
NT
Benzo-a-pyrene
3.0
NT
NT
NT
NT
NT
NT
Benzo-ghi-perylene
3.0
-0.004
158
-0.011
61
NT
NT
-------
95
Table 38. Kinetic data for PAH degradation/transformation in Grenada soils.
Compounds
Loading
Dry Wt.
(X)
K
(day-1)
T 1/2
(days)
95% Confidence Interval
Lower Limit
T 1/2
K
(day-1)
(days)
Upper Limit
U,T ^
(day-1) (days)
Naphthalene 0.33 -0.531
2-Methylnaphthalene 0.33 -0.529
1-Methylnaphthalene 0.33 -0.498
Bi phenyl 0.33 -0.484
Acenaphthylene 0.33 -0.154
Acenaphthene 0.33 -0.163 4
Dibenzofuran 0.33 -0.160 4
Fluorene 0.33 -0.161 4
Phenanthrene 0.33 -0.126 5
Anthracene 0.33 -0.067 10
Carbazole 0.33 -0.255 3
Fluoranthene 0.33 -0.011 65
Pyrene 0.33 -0.010 68
1,2 Benzanthracene 0.33 -0.001 3466
Chrysene 0.33 -0.004 173
Benzo-a-pyrene 0.33 -0.001 3466
Benzo-ghi-perylene 0.33 -0.001 770
0.560
1
-0.502
1
0.549
1
-0.508
1
0.519
1
-0.476
1
0.486
1
-0.482
1
0.279
2
-0.030
23
0.251
3
-0.075
9
0.243
3
-0.077
9
•0.257
3
-0.065
11
0.215
3
-0.038
18
¦0.142
5
NTa
NT
0.378
2
-0.132
5
>0.014
51
-0.008
. 91
•0.013
53
-0.007
95
>0.004
169
NT
NT
>0.007
95
-0.001
866
-0.002
433
NT
NT
-0.006
126
NT
NT
aNT « no transformation observed.
^ND » not detected.
-------
96
Table 38. Kinetic data for PAH degradation/transformation in Grenada soils,
(continued)
95% Confidence Interval
Lower Limit Upper Limit
Loading K T 1/2 —K r 1/2 K T 1/2"
Compounds Dry Wt. (day-1) (days) (dayl) (days) (day-1) (days)
(X)
Naphthalene
1.0
-0.568
1
-0.596
1
-0.540
1
2-Methylnaphthalene
1.0
-0.562
1
-0.581
1
-0.543
1
1-Methylnaphthalene
1.0
-0.532
1
-0.549
1
-0.515
I
Biphenyl
1.0
-0.510
1
-0.520
1
-0.501
1
Acenaphthylene
1.0
-0.518
1
-0.519
1
-0.516
1
Acenaphthene
1.0
-0.577
1
-0.577
1
-0.577
1
Oibenzofuran
1.0
-0.568
1
-0.573
1
-0.564
1
Fluorene
1.0
-0.579
1
-0.584
1
-0.575
1
Phenanthrene
1.0
-0.058
2
-0.076
9
-0.040
17
Anthracene
1.0
-0.026
27
-0.037
19
-0.016
45
Carbazole
1.0
-0.539
1
-0.555
1
-0.524
1
Fluoranthene
1.0
-0.019
36
-0.027
25
-0.011
65
Pyrene
1.0
-0.016
45
-0.023
30
-0.008
86
1,2 Benzanthracene
1.0
-0.007
107
-0.011
66
-0.002
285
Chrysene
1.0
-0.007
102
-0.011
64
-0.003
248
Benzo-a-pyrene
1.0
NT
NT
NT
NT
NT
NT
Benzo-gh i-pery1ene
1.0
NT
NT
NT
NT
NT
NT
-------
97
Table 38. Kinetic data for PAH degradation/transformation in Grenada soils,
(continued)
Compounds
Loading K T 1/2
Dry Wt. (day-1) (days)
(*)
95% Confidence Interval
Lower Limit
T
TTTI
Upper Limit
"i
(day-1) (days) (day-1)
TI77
(days)
Naphthalene
2-Methylnaphthalene
l*Methylnaphthalene
B1 phenyl
Acenaphthylene
Acenaphthene
Oibenzofuran
Fluorene
Phenanthrene
Anthracene
Carbazole
Huoranthene
Pyrene
1»2 Benzanthracene
Chrysene
Benzo-a-pyrene
Benzo-ghi-perylene
3.0
NO
ND
ND
ND
ND
ND
3.0
NO
ND
ND
ND
ND
ND
3.0
NO
ND
ND
ND
NO
ND
3.0
-0.523
1
-0.524
1
-0.522
1
3.0
ND
ND
ND
ND
NO
ND
3.0
ND
ND
NO
ND
ND
NO
3.0
-0.006
116
-0.009
75
-0.003
248
3.0
ND
ND
ND
ND
ND
ND
3.0
-0.095
7
-0.351
2
NT
NT
3.0
-0.087
8
-0.348
2
NT
NT
3.0
ND
ND
NO
ND
ND
ND
3.0
-0.033
21
-0.049
14
-0.017
42
3.0
-0.033
21
-0.036
19
-0.029
24
3.0
-0.030
23
-0.038
18
-0.022
31
3.0
-0.010
72
-0.016
43
-0.010
72
3.0
NT
NT
NT
NT
NT
NT
3.0
ND
ND
ND
ND
ND
ND
-------
98
Table 39. Kinetic data for PAH degradation/transformation in Meridian soils.
95% Confidence Interval
Lower
Limit
Upper Limit
Loading
K
T 1/2
K
T 1/2
K
T 1/2
Compounds
Dry Wt.
(*)
(day-1)
(days)
(day-1)
(days)
(day-1)
(days)
Naphthalene
0.33
-0.542
1
-0.551
1
-0.533
1
2-Methylnaphthalene
0.33
-0.490
1
-0.513
1
-0.467
1
1-Methylnaphthalene
0.33
-0.490
1
-0.514
1
-0.466
1
Bi phenyl
0.33
-0.166
4
-0.626
1
NTa
NT
Acenaphthylene
0.33
-1.551
1
-0.586
1
NT
NT
Acenaphthene
0.33
-0.523
1
-0.532
1
-0.515
1
Dibenzofuran
0.33
-0.544
1
-0.548
1
-0.537
1
Fluorene
0.33
-0.544
1
-0.548
1
-0.539
1
Phenanthrene
0.33
-0.136
5
-0.284
2
NT
NT
Anthracene
0.33
-0.180
ND5
4
-0.407
2
NT
NT
Carbazole
0.33
NO
ND
ND
ND
ND
Fluoranthene
0.33
-0.017
41
-0.036
19
NT
NT
Pyrene
0.33
-0.013
53
-0.022
32
-0.003
205
1,2 Benzanthracene
0.33
-0.005
139
-0.012
58
NT
NT
Chrysene
0.33
NT
NT
NT
NT
NT
NT
Benzo-a-pyrene
0.33
NO
NO
NO
NO
ND
NO
Benzo-ghi-perylene
0.33
ND
ND
ND
ND
ND
ND
aNT ¦ no transformation observed.
bND » not detected.
-------
99
table 39. Kinetic data for PAH degradation/transformation in Meridian soils,
(continued)
95% Confidence Interval
Upper Limit
Compounds
Loading
Dry Wt.
(*)
K
T 1/2
K
' t 1/2
K
T 1/2
(day-1)
(days)
(day-1)
(days)
(day-1)
(days)
-0.108
6
-0.285
2
NT
NT
-0.096
7
-0.272
3
NT
NT
-0.091
8
-0.264
3
NT
NT
-0.086
8
-0.026
27
NT
NT
-0.083
8
-0.256
3
NT
NT
-0.101
7
-0.028
25
NT
NT
-0.109
6
-0.289
2
NT
NT
-0.107
7
-0.286
2
NT
NT
-0.018
38
-0.044
16
NT
NT
-0.025
28
-0.161
4
NT
NT
-0.096
7
-0.273
3
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
-0.048
15
-0.146
5
NT
NT
-0.043
16
-0.142
5
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
NT
Naphthalene 1.0
''Methylnaphthalene 1.0
^Methyl naphthalene 1.0
°iphenyl 1.0
Jcenaphthylene 1.0
Jcenaphthene 1.0
Dlbenzofuran 1.0
^luorene 1.0
jhenanthrene 1.0
Anthracene 1.0
Cdrbazole 1.0
Huoranthene 1.0
fyrene 1.0
s2 Benzanthracene 1.0
Chrysene 1.0
8enzo-a-pyrene 1.0
Benzo-ghi-perylene 1.0
-------
100
Table 39. Kinetic data for PAH degradation/transformation in Meridian soils,
(continued)
95X Confidence Interval
Lower
Limit
Upper
Limit
Loading
K
T 1/2
K
T 1/2
K
T 1/2
Compounds
Dry Wt.
(*)
(day-1)
(days)
(day-1)
(days)
(day-1)
(days)
Naphthalene
3.0
-0,606
1
-0.637
1
-0.574
1
2-Methy1 naphthalene
3.0
-0.577
1
-0.586
1
-0.567
1
1-Methylnaphthalene
3.0
-0.557
1
-0.561
1
-0.553
1
Biphenyl
3.0
-0.516
1
-0.520
1
-0.512
1
Acenaphthylene
3.0
-0.539
1
-0.547
1
-0.531
1
Acenaphthene
3.0
-0,124
6
-0.267
3
NT
NT
Dibenzofuran
3.0
-0.070
10
-0.221
3
NT
NT
Fluorene
3.0
-0.082
8
-0.253
3
NT
NT
Phenanthrene
3.0
-0.086
8
-0.242
3
NT
NT
Anthracene
3.0
-0.124
6
-0.274
3
NT
NT
Carbazole
3.0
-0.585
1
-0.592
1
-0.579
1
Fluoranthene
3.0
-0.008
90
-0.019
37
NT
NT
Pyrene
3.0
NT
NT
NT
NT
NT
NT
1,2 Benzanthracene
3.0
-0.060
12
-0.206
3
NT
NT
Chrysene
3.0
-0.062
11
-0.216
3
NT
NT
Benzo-a-pyrene
3.0
NT
NT
NT
NT
NT
NT
Benzo-gh i-pery1ene
3.0
NO
NO
NO
NO
NO
NO
-------
101
Table 40. Kinetic data for PAH degradation/transformation in Wiggins soils.
Compounds
Loading
Dry Wt.
(X)
K
(day-1)
T 1/2
(days)
95% Confidence Interval
Lower Limit
T
TT7?
(day-1) (days)
Upper Limit
k T-1/2
(day-1) (days)
Naphthalene 0.33
2-Methylnaphthalene 0.33
l-Methylnaphthalene 0.33
®iphenyl 0.33
Acenaphthylene 0.33
Jcenaphthene 0.33
^ibenzofuran 0.33
^uorene 0.33
^enanthrene 0.33
jyithracene 0.33
^rbazole 0.33
^luoranthene 0.33
fyrene 0.33
•»2 Benzanthracene 0.33
^ysene 0.33
°*nzo-a-pyrene 0.33
B®nzo-gh1-perylene 0.33
-0.523
-0.518
-0.492
-0.490
-0.150
-0.270
-0.271
-0.277
-0.178
-0.164
-0.174
-0.024
-0.122
-0.016
-0.260
ND°
NO
1
1
1
1
5
3
3
3
4
4
4
29
6
43
3
NO
NO
-0.529
1
-0.518
1
-0.522
1
-0.514
1
-0.505
1
-0.479
1
-0.496
1
-0.485
1
-0.565
1
-0.266
3
-0.422
2
-0.119
6
-0.421
2
-0.121
6
-0.434
2
-0.120
6
-0.258
3
-0.097
7
-0.248
3
-0.081
9
-0.276
3
-0.072
10
-0.035
20
-0.013
53
-0.221
3
-0.023
30
-0.106
7
NT®
NT
-0.391
2
-0.129
5
NO
NO
NO
ND
NO
NO
NO
NO
aNT ¦ no transformation observed.
* not detected.
-------
102
Table 40. Kinetic data for PAH degradation/transformation in Wiggins soils,
(continued)
Compounds
Loading
Dry Wt.
(%)
K
(day-1)
T 1/2
(days)
95%
Lower
K
(day-1)
Confidence
Limit
T 1/2
(days)
Interval
Upper
(day-1)
Limit _
" T 171
(days!
Naphthalene
1.0
-0.117
6
-0.267
3
NT
NT
2-Methylnaphthalene
1.0
-0.119
6
-0.263
3
NT
NT
1-Methylnaphthalene
1.0
-0.266
3
-0.412
2
-0.119
6
Biphenyl
1.0
-0.258
3
-0.391
2
-0.125
6
Acenaphthylene
1.0
-0.253
3
-0.384
2
-0.123
6
Acenaphthene
1.0
-0.017
41
-0.143
5
NT
NT
Dibenzofuran
1.0
-0.012
58
-0.029
24
NT
NT
Fluorene
1.0
-0.012
58
-0.032
22
NT
NT
Phenanthrene
1.0
-0.012
58
-0.310
2
NT
NT
Anthracene
1.0
NT
NT
NT
NT
NT
NT
Carbazole
1.0
NT
NT
NT
NT
NT
NT
Fluoranthene
1.0
-0.012
58
-0.023
30
-0.001
693
Pyrene
1.0
NT
NT
NT
NT
NT
NT
1,2 Benzanthracene
1.0
-0.001
693
-0.007
99
NT
NT
Chrysene
1.0
NT
NT
NT
NT
NT
NT
Benzo-a-pyrene
1.0
NT
NT
NT
NT
NT
NT
Benzo-ghi-perylene
1.0
-0.525
1
-0.544
1
-0.506
1
-------
103
Table 40. Kinetic data for PAH degradation/transformation in Wiggins soils,
(continued)
95% Confidence Interval
Lower Limit Upper Limit
Loading K T 1/2 < TUT K T 1/2
Compounds Dry Wt. (day-1) (days) (day-1) (days) (day-1) (days)
(*)
Naphthalene
2-Methylnaphthalene
1-Methylnaphthalene
Biphenyl
Acenaphthylene
^cenaphthene
^benzofuran
^uorene
phenanthrene
Anthracene
Carbazole
Huoranthene
Pyrene
Benzanthracene
^hrysene
Benzo-a-pyrene
Benzo-ghi-perylene
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
¦0.202
•0.201
-0.155
-0.564
-0.542
-0.040
-0.025
-0.030
¦0.034
•0.014
-0.013
-0.015
-0.002
•0.005
-0.001
-0.190
NO
3
-0.315
2
-0.089
8
3
-0.311
2
-0.091
8
4
-0.280
2
-0.031
22
1
-0.565
1
-0.563
1
1
-0.548
1
-0.536
1
17
-0.059
12
-0.022
32
28
-0.043
16
-0.007
99
23
-0.048
14
-0.013
53
20
-0.052
13
-0.016
43
50
-0.023
30
-0.005
139
53
-0.020
35
-0.006
116
46
-0.032
22
NT
NT
347
-0.007
99
NT
NT
139
-0.011
63
NT
NT
7
-0.007
99
NT
NT
4
-0.376
2
-0.004
173
ND
ND
ND
ND
NO
-------
104
Table 41. Kinetic data for PCP degradation/transformation in site soils.
95X Confidence Interval
Lower Limit Upper Limit
— TT7I k T i)i
(day-1) (days) (day-1) (days)
Meridian
3.0
NTa
NT
NT
NT
NT
NT
1.0
-0.0096
72
-0.0176
30
-0.0015
462
0.3
-0.0152
43
-0.0206
34
-0.0115
60
Grenada
3.0
-0.0335
21
-0.0482
14
-0.0188
37
1.0
-0.0131
53
-0.0263
26
NT
NT
0.3
-0.0152
46
-0.0178
39
-0.0125
55
Columbus
3.0
-0.0018
385
-0.0028
248
-0.0009
758
1.0
NT
NT
NT
NT
NT
NT
0.3
-0.0006
1087
-0.0021
334
NT
NT
Wi ggi ns
3.0
-0.0066
105
-0.0200
35
NT
NT
1.0
-0.0076
91
-0.0235
29
NT
NT
0.3
-0.0060
116
-0.0217
32
NT
NT
aNT » no transformation observed.
Loading it T 1/2
Site Ory Wt. (day-1) (days)
(*)
-------
105
Table 42. Kinetic data for OCDO degradation/transformation in site soils.
95% Confidence Interval
Site
Loading
Dry Wt.
(*)
K
(day-1)
T 1/2
(days)
Lower
K
(day-1)
Limit
T 1/2
(days)
Upper Limit
K T 1/2
(day-1) (days)
Pridian
3.0
NTa
NT
NT
NT
NT
NT
1.0
NT
NT
NT
NT
NT
NT
0.3
-0.1251
6
-0.1959
4
-0.0543
13
Grenada
3.0
-0.0152
46
-0.0178
39
-0,0125
55
1.0
-0.01973
35
-0.03935
18
-0.00011
6301
0.3
-0.0006
1161
-0.0053
130
NT
NT
Columbus
3.0
NT
NT
NT
NT
NT
NT
1.0
-0.001
663
-0.004
160
NT
NT
0.3
NT
NT
NT
NT
NT
NT
Wiggins
3.0
1.0
0.3
NT
NT
-0.0009
NT
NT
766
NT
NT
-0.0023
NT
NT
301
NT
NT
NT
NT
NT
NT
aNT m no transformation observed.
-------
106
Table 43. Starting and peak microbe counts.3
Columbus Grenada Meridian Wiggins
Media Dry Wt. Start Peak Start Peak Start Peak Start Pea
(X)
P 0.3
.07A
. 15A
.05 A
4.408
,31A
2.10B
.22A
5.10b
1.0
.02A
.10A
.04A
6.908
.33 A
4.10B
.09A
6.10B
3.0
.01A
.148
.05 A
4.808
.24A
5.10B
.05A
4.10
C 0.3
• 50A
.50A
.84A
9.408
2.70A
3.50A
.40A
4.20B
1.0
.47A
Z.OOB
1.20A
7.606
2.20 A
3.80B
.20 A
3.00"
3.0
.50 A
2.00B
.70A
7.10B
2.90A
4.608
.26A
3.90
C+P 0.3
.09A
.858
.06 A
4.408
.29A
2.608
.27A
5.508
1.0
.01A
.39B
.04A
8.208
.30 A
4.008
.10A
6.40
3.0
.01A
. 11B
.04 A
5.80B
.23A
4.608
.05A
4.70
NA
0.3
.67A
2.60B
.48 A
8.40B
3.20A
3.40A
.42A
5.10"
1.0
.88 A
2.10B
.92A
6.908
3.00A
4.15A
.39A
5.80
3.0
.74A
1.70B
.52 A
9.608
3.60 A
4.808
.05A
4.70#
PDA
0.3
.90A
2.408
1.10A
10.008
3.20A
3.20A
. 51A
5.70/
1.0
.91A
2.50B
1.40 A
9.108
2.98 A
4.SOB
.29 A
6.10-
3.0
.57 A
2.90B
1.10A
9.508
3.30A
6.408
.27A
5.308
PDAA 0.3
1.0
3.0
.05A .05A
.02A .04A
.01A .058
.04A 1.108
,04A .70 B
.02A .30B
.13A .17A
•13A .13A
.10A .19B
.05A .16
.05A .11*
.07A .07A
aStart1ng and peak microbe count means within a site, media, and loading rate are not
different by Duncan's Multiple Range Test (P » 0.05) if followed by the same letter.
-------
107
lives of more than one hundred days. Naphthalene, 2-methylnaphthalene,
1-methylnaphthalene, biphenyl, acenaphthalene, acenaphthene,
dibenzofuran, and fluorene have half lives of ten days or less in most
cases. Phenanthrene, anthracene, carbazole, and fluoranthene have half
lives between ten and one hundred days in most cases. Pyrene,
1,2-benzanthracene, chrysene, benzo-a-pyrene, and benzo-ghi-perylene
"have half lives greater than one hundred days in most cases. In several
cases these last five showed essentially no breakdown within the time
frame of the experiment.
The breakdown rates of individual PAH's were apparently related to
molecular size and structure, as noted in previous studies. The zero to
ten day half life group contained compounds with two aromatic rings, the
ten to one hundred day half life group contained compounds with three
aromatic rings, and the one hundred plus day half life group contained
compounds with four or more aromatic rings. However, some of the
larger, most recalcitrant compounds apparently were broken down readily
in some situations. This gives hope that even the most persistent PAH's
might yield to biological remediation techniques under the right
conditions with appropriate microbial populations.
Carbazole, a compound containing a nitrogen bridge between two
aromatic rings, varied greatly in persistence in different soils and
loadings. This may be due to the nitrogen atom affecting water
solubility and other properties of carbazole under varying local
oxidation/reduction potentials and pH.
Acenaphthylene and acenaphthene, differing only in the presence or
absence of a double bond (and two hydrogens) show the effect of small
changes in structure. Acenaphthene had much longer average half life
-------
108
than acenaphthylene. Apparently, the double bond is easier to attack,
although the single bond in acenapthene also lowers the vapor pressure,
possibly affecting the half life by vaporization.
The microbial populations found in the plate counts were not
closely related to PAH breakdown, since PAH breakdown was similar at
similar concentrations over the four sites, while microbe counts
varied.
PCP transformation occurred in all the soils, but was slow in
Columbus soil, which was from a site not exposed to PCP treatment
wastes. Grenada soil transformed PCP with half lives ranging from one
to two months, a quite practical range for land treatment operations.
Meridian soil also exhibited rapid transformation rates except at the
highest loading rate. Wiggins soil transformed PCP with half lives of
three to four months, still an appropriate range for land treatment
operations especially considering its deep south location where soil
temperatures are high enough for good microbiological activity most of
the year. Although the Columbus soil did exhibit some transformation of
PCP, the low rates would bring into question the practicality of land
treating PCP at that location. However, it is not known what length of
time is required to build up a population of microorganisms suitable for
rapid degradation of PCP in hitherto unexposed soil. Evidently, the
relatively short time frame of these experiments was insufficient for
the Columbus soil, at least. It is likely in most soils with chronic
exposure to PCP (which is where PCP disposal by landfarming would be
needed) that suitable populations could be induced relatively quickly.
OCQD transformation occurred to some degree in all the soils, but
only Grenada soil consistently transformed OCDD at all loadings. Since
-------
109
Grenada soil also consistently transformed PCP, a relationship may exist
in the potential for a soil to transform these two compounds. Dioxins
are widely regarded as being somewhat recalcitrant to biological
transformation, but these data indicate the potential for biological
treatment. Concentrated sources of dloxlns would probably be
incinerated, but biological treatment in soil could be very useful for
materials such as wood treating wastes that contain low levels of
dioxins.
General Discussion
The results of these experiments indicate that PAH's, PCP, and OCDD
can be transformed at practically useful rates in soil. Although the
variability of the data is relatively large in some cases, the general
trend 1s clear. Land treatment of creosote and PCP wood treating wastes
appears to provide a viable management alternative based on treatability
data 1n the soils tested to date. The data variability does support the
need for conducting site-specific treatability studies to discern the
appropriate operation and management scenario for a given site.
Further study of treatment of OCDD, PCP, and the higher molecular
weight PAH's is needed to determine the most advantageous environmental
conditions and management techniques for more rapid transformation of
these compounds. Many of these compounds were readily transformed in
some cases. Therefore, further study may reveal reliable techniques for
enhancing land treatment as a practically useful management alternative
for these recalcitrant compounds. Since the environmental problems that
the wood treating industry has to deal with are almost unlimited, and
the resources available to solve these problems are quite limited, a
reliable, safe, economical remediation technique such as land treatment
is very attractive.
-------
110
REFERENCES
Adams, J. and C. Giam. 1984. Polynuclear Azaarenes in Wood
Preservative Wastewater. Environ. Sci. Technol. 18(5):391-394.
Ahlborg, V. G., J. E. Lindgren, and H. Mercler. 1974. Metabolism of
Pentachlorophenol. Arch. Toxicol. 32(4):271-281.
AlHot, H. 1975. Chlorod1ox1ns 1n Pentachlorophenol. British Wood
Pres. Assoc. News Sheet. London.
Allison, L. E. 1935. Organic soil carbon by reduction of chromic
acid. Soil Sci. 40:311-320.
Anderson, K. J., E. G. Lelghty, and M. T. Takahashi. 1972. Evaluation
of Herbicides for Possible Mutagenic Properties. J. Agr. Food
Chem. 20:649-656.
Barr, A. J., J. H. Goodnight, and J. P. Sail. 1979. SAS Users Guide.
SAS Institute, Raleigh, NC, 494 pp.
Becker, G. 1977. Experience and Experiments with Creosote for
Crossties. Proc. Am. Wood-Pres. Assoc. 73:16-25.
Bevenue, A. and H. Beckman. 1967. Pentachlorophenol: A Discussion of
Its Properties and Its Occurrence as a Residue in Human and Animal
Tissues. Residue Rev. 19:83-134.
Blake, G. R. 1965. Bulk density: Core method. In C. A. Black (Ed.)
Methods of Soil Analysis, Part I, Agronomy 9:375-377. Amer. Soc.
of Agron., Madison, WI.
Braun, W. H. and M. W. Sauerhoff. 1976. The Pharmacokinetic Profile of
Pentachlorophenol in Monkeys. Toxicol. Appl. Pharmacol.
38:525-533.
Briggs, G. G. 1975. The Behavior of the Nitrification Inhibitor
"N-Servew in Broadcast and Incorporated Application to Soil. J.
Sci. Food Agric. 26:1083-1092.
Brown, K. W. and Associates. 1980. Hazardous Waste Land Treatment.
SW-874, U. S. Environmental Protection Agency, Washington, DC.
and K. C. Donnelly. 1984. Mutagenic Activity of Runoff
and Leachage Water from Hazardous Waste Land Treatment. Environ.
Pollut. (Series A) 35:229-246.
Bulman, T. L., S. Lesage, P. J. A. Fowles, and M. D. Webber. 1985. The
Persistence of Polynuclear Aromatic Hydrocarbons in Soil. PACE
Report No. 85-2, Petroleum Assoc. for Conservation of the Canadian
Environ. Ottawa, Ontario.
-------
Ill
Burdell, C. A. 1984. Overview of the Wood Preserving Industry, pp.
7-14. IN: Hazardous Waste Treatment and Disposal in the Wood
Preserving Industry, Atlanta, GA.
Buselmaier, W., G. Roehrborn, and P. Propping. 1973. Comparative
Investigations on the Mutagenicity of Pesticides in Mammalian Test
Systems. Mutat. Research 21(1):25-26.
Buser, H. R. 1975. Polychlorinated Dibenzo-p-dioxins, Separation and
Identification of Isomers by Gas Chromatography - Mass
Spectrometry. J. Chromatog. 114:95-108.
. 1976. High Resolution Gas Chromatography of
Polychlorinated Dibenzo-p-dioxins and Dibenzofurans. Anal. Chem.
48:1553.
Butterfield, D. J. and J. D. Devay. 1975. An Improved Soil Assay for
Verticillim dahliae. Proc. Am. Phytopathol. Soc. 2:111 (Abstract).
and J. D. Oevay. 1977. Reassessment of Soil Assay for
Verticillim dahliae. Phytopathology 67:1073-1078.
Carrol, D. 1970. Clay minerals: A guide to their X-ray
Identification. The Geological Society of America. Special paper
126. Boulder, CO. 80 p.
Cerniglia, C. E. and D. T. Gibson. 1979. Oxidation of Benzo(a)-pyrene
by the Filamentous Fungus Cunninahamelia eleqans. J. Biol. Chem.
254(23):12174-12180.
and S. A. Crow. 1981. Metabolism of Aromatic Hydrocarbons
by Yeasts. Arch. Microbiol. 129:9-13.
. 1984. Microbial Metabolism of Polycydic Aromatic
Hydrocarbons, pp. 30-71. IN: A. I. laskin, Ed. Adv. in Appl.
Microbiol., Vol. 30, Academic Press, New York, NY.
Choi, J. and S. Aomfne. 1972. Effects of the Soil on the Activity of
Pentachlorophenol. Soil Sc1. Plant Nutr, 18(5).255-260,
1974. Adsorption of Pentachlorophenol by Soils. Soil
Sci. Plant Nutr. 20(2):135-144.
. 1974a. Mechanisms of Pentachlorophenol Adsorption by
Soils. Soil Sci. Plant Nutr. 20(4):37l-379.
Chu, J. P. and E. J. Kirsch. 1972. Metabolism of Pentachlorophenol by
an Axenic Bacterial Culture. Appl. Microbiol, 23(5):1033-1035.
. 1973. Utilization of Halophenolsbya Pentachlorophenol
Metabolizing Bacterium. Dev. Ind. Microbiol. 14:264-273.
Crosby, D. G. 1981. Environmental Chemistry of Pentachlorophenol. Pure
Appl. Chem. 53:1052-1080.
-------
112
Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Blodeterior. Bull. 8(4):135-138.
Day, P. R. 1965. Particle fractionation and particle size analysis.
In C. A. Black (Ed.) Methods of Soil Analysis, Part I. Agronomy
7T552-562. Amer. Soc. of Agron., Madison, WI.
Deichmann, W. B., W. Machle, K. V. Kltzmiller, and G. Thomas. 1942.
Acute and Chronic Effects of Pentachlorophenol and Sodium
Pentachlorophenate upon Experimental Animals. J. Pharm. Exptl.
Therap. 76:104.
and I. J. Schafer. 1942. Spectrophotometric Estimation of
Pentachlorophenol in Tissues and Water. Ind. Eng. Chem., Anal. Ed.
14(4):310-312.
Demidenko, N. M. 1966. Toxicological Properties of Pentachlorophenol.
Gig. Toksikol. Pestits. Klin. Otravleni. (4):234-239.
. 1969. Maximum Permissible Atmospheric Concentration of
Pentachlorophenol. Gig. Tr. Prof. Zabol. 13(9):58-60. (CA
72:47095M).
Dixon, J. B. and S. B. Weed. 1978. Minerals in Soil Environments.
Soil Sci. Soc. of Amer., Madison, WI.
Oodge, R. H. and 0. T. Gibson. 1980. Fungal Metabolism of
Benzo(a)anthracene. p. 138. IN: Abstracts of the 1980 American
Society for Microbiologists Annual Meeting. ASM, Washington, DC.
Dow Chemical Co. 1969. Toxicity Summary for Dowicide 7.
Qreisbach, R. H. 1963. Handbook of Poisoning: Diagnosis and
" Treatment, p. 256.
Edgehill, R. U. and R. K. Finn. 1982. Isolation, Characterization and
Growth Kinetics of Bacteria Metabolizing Pentachlorophenol. Eur.
J. Appl. Microbiol. Biotechnol. 16:179-184.
Edwards, N. T. 1983. Polycyclic Aromatic Hydrocarbons (PAH's) in the
Terrestrial Environment—a Review. J. Environ. Qual. 12:427-441.
EPRI. 1984. Development and Validation of a Terrestrial Microcosm Test
System for Accessing Ecological Effects of Utility Wastes, Final
Report. EA-XXXX-RP1224-5.
ERT, Inc. 1985b. The Land Treatability of Creosote Wastes (second
draft). Oocument No. P0481-400a, Environmental Research and
Technology, Concord, MA.
Evans, W. C., H. N. Fernley, and E. Griffiths. 1965. Oxidative
Metabolism of Phenanthrene and Anthracene by Soil Pseudomonads.
Biochem. J. 95:791-831.
-------
113
Feci. Proc. 1943. Fed. Am. Soc. Exp. Biol. 2:76.
Fernley, H. N. and W. C. Evans. 1958. Oxidative Metabolism of
Polycyclic Hydrocarbons by Soil Pseudomonads. Nature 182:373-375.
Gabrllevskaya, L. N. and V. P. Laskina. 1964. Maximum Permissible
Concentrations of PCP and Na-Pentachlorophenolate in Water
Reservoirs. Sanit. Okhrana Vodoemov. ot. Zagrvaznenlya Prom.
Stochnymi Vodami. (6):251-272• (CA 62;15304dj.
Gaines, T. H. 1969. Acute Toxicity of Pesticides. Toxicol. Appl.
Pharmacol. 14(3):515-534.
Gardner W. S.. R. F. Lee, K. R. Tenore, and L. W. Smith. 1979.
Degradation of Selected Polycydic Aromatic Hydrocarbons in Coastal
Sediments: Importance of Microbes and Polychaete Worms. Water,
A1r, Soil Pollution 11, 339.
Gibson, D. T. 1972. The Microbial Oxidation of Aromatic Hydrocarbons.
Crit. Rev. Microbiol. 1(2):199-223.
V. Mahadevan, D. M. Jerina, H. Yagi, and H. J. C. Yeh.
1575. Oxidation of the Carcinogens Benzo(a)pyrene and
Benzo(a)anthracene to Dihydrodiols by a Bacterium. Science
189:295-297.
Groenewegen, D. and H. Stolp. 1976 Microbial Breakdown of Pol,cyclic
Aromatic Hydrocarbons. Tbl. Bakt. Hyg. It Abt.. 0r1g. 8162,225.
1981 Microbial Breakdown of Polycyclic Aromatic
Rydrocarbons, pp. 233-240. IN: M. R. Overcash, ad. Decomposition
of Toxic and Nontoxic Organic Compounds in Soils. Ann Arbor Science
Publishers, Inc., Ann Arbor, MI.
Harr-Unn n l 1959 The Toxicity of Wood Preservatives to Stock,
pSrt ?; Pentachlorophenol. NeJ Zealand Vat. J. 7:89-98. (CA
55:23814e}.
Herbes. S. E and L. R. Schwall. 1978. Microbial Transformations of
Polvcvclic Aromatic Hydrocarbons in Pristine and
Petroleum-Contaminated Sediments. Appl. Environ. Microbiol. 35,
306.
G R Southworth, D. L. Shaeffer, W. H. Griest, and M. P.
RIsSFrtec: 1980. Critical Pathways of Polycyclic Aromatic
Hydrocarbons in Aquatic Environments, pp. U3 128. IN. H.
Witschi, ed. The Scientific Bases of Toxicity Assessment,
Elsevier, Holland.
Hetrick L A 1952. The Comparative Toxicity of Some Organic
Insecticides as Termite Soil Poisons. J. Econ. Entomol.
45(2):235-237.
-------
114
Hilton, H. W. and Q. H. Yuen. 1963. Adsorption of Several
Pre-Emergence Herbicides by Hawaiian Sugar Cane Soils. J. Agric.
Food Chem. 11(3):230-234.
. and N. S. Nomura. 1970. Distribution of Residues from
Atrazine, Ametryne, and Pentachlorophenol in Sugarcane. J. Agric.
Food Chem. 18(2)217-220.
Hinkle, D. K. 1973. Fetotoxic Effects of Pentachlorophenol in the
Golden Syrian Hamster. Tox. and Appl. Pharmacol. 25(3):455
(abstract).
Huddleston, R. L., C. A. Bleckmann, and J. R. Wolfe. 1986. Land
Treatment Biological Degradation Processes, pp. 41-61. IN: R. C.
Loehr and J. F. Malina, Jr., eds. Land Treatments Hazardous Waste
Management Alternative. Water Resources Symp. No. 13, Center for
Research 1n Water Resources, Univ. of Texas at Austin, TX.
Ide, A., Y. Niki, F. Sakamoto, I. Watanabe, and H. Watanabe. 1972.
Decomposition of Pentachlorophenol in Paddy Soil. Agric. Biol.
Chem. 36(11)-.937-1844.
Jackson, M. L. 1956. Soil Chemical Analysis - advanced course. Publ.
by author, Univ. of Wisconsin, Madison.
Jaworski, E. G. 1955. Tracer Studies With l-14C-Pentachlorophenol in
Cotton. Proc. 10th Annu. Cotton Defol. Conf. pp. 36-40.
Johnson, R. L., P. J. Gehring, R. J. Koclba, and B. A. Schwetz. 1973.
Chlorinated Dlbenzodioxins and Pentachlorophenol. Environ. Health
Perspect. 5:171-175.
Karickhoff, S. W., 0. S. Brown, and T. A. Scott. 1979. Sorption of
Octanol/Water Distribution Coefficients, Water Solubilities, and
Sediment/Water Partition Coefficients for Hydrophobic Organic
Pollutants. EPA-600/4-79-032. U.S. Environmental Protection
Agency.
Kaufman, D. D. 1978. Degradation of Pentachlorophenol in Soil and by
Soil Microorganisms. IN: Pentachlorophenol, R. K. Rao, Ed. Plenum
Press, New York. pp. 27-40.
Kehoe, R. A., W. Delchmann-Gruebler, and K. V. Kitzmiller. 1939. Toxic
Effects upon Rabbits of Pentachlorophenol and Sodium
Pentachlorophenate. J. Indust. Hyg. & Toxicol. 21:160-172.
Kirsch, E. J. and J. E. Etzel. 1973. Microbial Decomposition of
Pentachlorophenol. J. Water Pollut. Control Fed. 45(2):359-364.
Klute, A. 1965. Laboratory measurement of hydraulic conductivity of
saturated soil. In C. A. Black (Ed.) Methods of Soil Analysis,
Part I. Agron. 9:714-215. Amer. Soc. of Agron., Madison, WI.
-------
115
Koss, G. and W. Koransky. 1978. Pentachlorophenol:Chemistry,
Pharmacology, and Environmental Toxicology, K. R. Rao, Ed. Plenum
Press, New York.
Kuwatsuka, S. and M. Igarashi. 1975. Degradation of Penta in Soils:
II. The Relationship Between the Degradation of Penta and the
Properties of Soils, and the Identification of the Degradation
Products of Penta. Soil Sci. Plant Nutr. 21(4):405-414.
Larsen, R. V., I. E. Kirsh, S. M. Shaw, J. 6. Christian, and G. S. Born.
1972. Excretion and Tissue Distribution of Uniformly Labeled
1 C-Pentachlorophenol in Rats. J. Pharm. Sci. 61:2004-2006.
G» S. Born, W. V. Kessler, S. M. Shaw, and D. C. Von
Sickle. 1975. Placental Transfer and Teratology of
Pentachlorophenol 1n Rats. Environ. Lett. 10(2):121-128.
Lorenz, L. R. and L. R. Gjovik. 1972. Analyzing Creosote by Gas
Chromatography:Relationship to Creosote Specifications. Proc.
Amer. Wood Pres. Assoc. 68:32-42.
Lousta?ot, A. J. and R. Ferrer. 1950. The Effect of Some Environmental
Factors on the Persistence of Sodium PentacMorophenate in the
Soil. Proc. Am. Assoc. Hortic. Sci. 56:294-298.
Matsunaka, S. and S. Kuwatsuka. 1975. Environmental Problems Related
to Herbicidal Use in Japan. Environ. Qual. Safety. 4:149-159.
Means, J. C., G. S. Wood, J. J. Hassett, and W. L. Banwart. 1979.
Sorption of Polynudear Aromatic Hydrocarbons by Sediments and
Soils. Environ. Sci. Technol. 14:1524-1528.
Medvedev, V. A. and V. D. Davidov. 1972. Transformation of Individual
Organic Products of the Coke Industry in Chernozem Soil.
Pochrovedenie. 11:22-28.
Miller, C. S. and M. M. Aboul-Ela. 1969. Fate of Pentachlorophenol in
Cotton. J. Agric. Food Chem. 17(6):1244-1246.
Mississippi State University. 1984. Methylene Chloride Soxhlet
Recoveries for 0CDD and PCP in Soil. Report for MFPUL
Environmental Group, Mississippi State, MS.
McKenna, E. J. and R. D. Heath. 1976. Biodegradation of Polynudear
Aromatic Hydrocarbon Pollutants by Soil and Water Microorganisms.
Water Resources Center, University of Illinois at Urbana-Champaign.
Research Report No. 113, UILU-WRC-76-0113.
Murthy, N. B. K., D. D. Kaufman, and G. F. Fries. 1979. Degradation of
Pentachlorophenol in Aerobic and Anaerobic Soil. J. of Environ.
Sci. Health, 814:1-14.
-------
116
Noakes, D. N. and D. M. Sanderson. 1969. A Method for Determining the
Dermal Toxicity of Pesticides. British J. of Indust. Med,
26:59-64.
Ochrymowych, J., Western Electric. 1978. Personal communication.
Overcash, M. R. and D. Pal. 1979. Design of Land Treatment Systems for
Industrial Wastes - Theory and Practice. Ann Arbor Science
Publishers, Inc., Ann Arbor, MI. 684 pp.
, J. B. Weber, and M. C. Miles. 1982. Behavior of Organic
Priority Pollutants in the Terrestrial System: Di(N-Butyl)
Phthalate Ester, Toluene, and 2,4-Din1trophenol. Office of Water
Research and Technology. U. S. Department of the Interior,
Washington, DC.
Peech, M. 1965. Exchange acidity. In C. A. Black (Ed.) Methods of
Soil Analysis, Part I, Agronomy 157914-926. Amer. Soc. of Agron.,
Madison, WI.
Phung, T., t. Barker, D. Ross, and D. Bauer. 1978. Land Cultivation of
Industrial Wastes and Municipal Solid Wastes: State-Qf-The-Art
Study. Volume 1. Technical Summary and Literature Review.
EPA-600/2-78-140a, U. S. Environmental Protection Agency,
Washington, DC.
Pleskova, A. and K. Bencze. 1959. Toxic Properties of
Pentachlorophenol. Pracovnl Lekerstvl, 11:348-354.
Reichhold Chemicals. 1974. Report of May 28, 1974.
Renberg, L. 1974. Ion Exchange Technique for the Determination of
Chlorinated Phenols and Phenoxy Acids in Organic Tissue, Soil, and
Water. Anal. Chem. 46(3):459-461.
Ricnards, L. A. 1949. Methods of Measuring Soil Moisture. Soil Sci.
68:95-112.
Rogoff, M. H. 1961. Oxidation of Aromatic Compounds by Bacteria. Adv.
Appl. Microbial. 3:193-221.
Schwetz, B. A. and P. J. Gehring. 1973. The Effect of
Tetrachlorophenol and Pentachlorophenol on Rat Embryonal and Fetal
Development. Toxicol. Appl. Pharmacol. 25(3):455. (Abstract).
, P. A. Keeler, and P. J. Gehring. 1974. The Effect of
Purified and Commercial Grade Pentachlorophenol on Rat Embryonal
and Fetal Development. Toxicol. Appl. Pharmacol. 28(1):151-161.
Shabad, L. M., Y. L. Cohan, A. P. Ilnltsky, A. Y. Xheslna, N. P.
Shcerbak, and G. A. Smirnov. 1971. The Carcinogenic Hydrocarbon
8enzo(a)pyrene in the Soil. J. Natl. Cancer Inst.
47(6): 1179-1191.
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117
Sims, R. C. 1982. Land Treatment of Polynuclear Aromatic Compounds.
Ph.D. Dissertation. Dept. Biol. Agr. Eng., North Carolina State
Univ., Raleigh, NC.
, and M. R. Overcash. 1983. Fate of Polynuclear Aromatic
Compounds (PNAs) in Soil~Plant Systems. Residue Rev. 88:1-68.
. J. L. Sims, D. L. Sorensen, and L. L. Hastings. 1987.
Waste/Soil Treatability Studies for Four Complex Industrial Wastes:
Methodologies and Results. Vol. 1. Project # CR-810979.
Sisler, F. D. and C. E. Zobell. 1947. Microbial Utilization of
Carcinogenic Hydrocarbons. Science 106:521-522.
Soil Survey Staff. 1951. Soil Survey Manual. Agrlc. Handb. No. 18,
USOA. U. S. Govt. Printing Office, Washington, D.C.
Sudhakar-Barik and N. Sethunathan. 1978. Metabolism of Nitrophenols in
Flooded Soils. J. Environ. Qual. 7:349-352.
Suzuki, T. and K. Nose. 1971. Decomposition of Pentachlorophenol in
Farm Soil fPart 2). Penta Metabolism by a Microorganism Isolated
S3 Soil! Noyaku Seisan Gijutsu, Japan, 26:21-24.
Tausson, V. 0. 1950. Basic Principles of . . .
(collected works), p. 73. In: N. A. Maximov, (Ed.), National
Academy of Sciences, USSR.
Tortensson, L. and J. Stenstrom. 1986. "Basle" Respiration Rate as a
Tool for Prediction of Pesticide Persistence 1n Soil. Toxicity
Assessment 1:57-72.
United States Department of Agriculture. 1972. Soil Survey Laboratory
Methods and Procedures f°r Co1lcctingSol1 Samples. Soil Survey
Investigations Report No. 1. U. S. Govt. Printing Office,
Washington, DC.
1980 The Biologic and Economic Assessment of
ftentachiorophenol Inorganic Arsenicals Creosote. USDA, Number
1658-11. Washington, DC.
U.S. EPA. 1975. Production, D1st;1b^1^' Use,,1
Impact Potential of Selected Pesticides. U. S. Environ. Prot.
Agency 540/1-74-001. 439 pp.
1978 Report of the Ad Hoc Study Group on
Pentac^iorophenol Contaminant.
Committee. Science Advisory Board, Washington, DC.
1983. 40CFR Parts 261, 264, 265, and 775. Federal
' Register. 48(65).
1984. Creosote - Special Review Position Document 213.
U. S. Environmental Protection Agency, Washington, DC.
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118
. 1986a. Test Methods for Evaluating Solid Waste. IB.
SW-846. Third Edition.
. 1986b. Permit Guidance Manual on Hazardous Waste Land
Treatment Demonstrations. Final Draft. EPA-530/SW86-032. Office
of Solid Waste and Emergency Response, U.S. Environmental
Protection Agency, Washington, DC.
Versar, Inc. 1979. Water-Related Environmental Fate of 129 Priority
Pollutants. Vol. 1 and 2, EPA 440/4-79-029. U.S. Environmental
Protection Agency, Washington, DC.
Verschueren, 0. 1977. Handbook of Environmental Data on Organic
Chemicals. Van Nostrand/Reinhold Co., New York. p. 659.
Vogel, E. and J. L. R. Chandler. 1974. Mutagenicity Testing of
Cyclamate and Some Pesticides in Drosophila melanoqaster.
Experientia 30(6)-.621-623.
Warcup, J. H. 1950. The Soil Plate Method for Isolation of Fungi from
Soil. Nature 166:117-118.
Ward, C. H., M. B. Thomson, P. B. Bedient, and M. D. Lee. 1986.
Transport and Fate Processes 1n the Subsurface, pp. 19-39. IN: R.
C. Loehr and J. F. Malina, Jr., Eds. Land Treatments Hazardous
Waste Management Alternative. Water Resources Symp. No. 13, Center
for Research 1n Water Resources, Univ. of Texas at Austin, TX.
Watanabe, I. 1973. Isolation of Pentachlorophenol Decomposing Bacteria
from Soil. Soil Sci. Plant Nutr. Tokyo. 19(2}:109—116.
Williams, R. T. 1959. Detoxification Mechanisms. 2nd Ed., John Wiley
and Sons, Inc., New York, NY. 796 pp.
Young, H, C. and J. C. Carroll. 1951. The Decomposition of
SerS"lii:OPAg"i.U!3!n43?lii-1o?! * ReSi0Ml P""E"»^ence
Yuan^9^9.^Determination ^Exchangeable Hydrogen „ Soils by .
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appendix a
methodology
TABLE OF CONTENTS
PA6E
Extraction of PCP, PAH's, and OCDD from Soil 121
Clean-up and Determination of PAH's and PCP 1. Soil Extracts. . . 121
Clean-up and Determination of Octachlorodibenzo-p dloxln
in Soil (MSU 1984)
Quality Assurance Program for Soil Extraction and Analysis. ... 125
127
Site and Soil Characterization
Transformation/Degradation Using a Standard 12g
Mixture: Experiment I
Transformation/Degradation of Site Specific fudges ^
Experiment II
Rationale for the Addition of Manure^to SoIMn the ^ ^ ^
Degradatlon/Transformatlon Studi es.
133
Microbiological Procedures
136
Statistical Procedures
List of Tables:
A-l. Analytical procedures for soil and water
120
A*2. Analytical procedures for sludges
ie ox loading before and
A*3. Bacteria levels 1" Jour s 134
after addition of chicken manure.
* * ntut pcp and dioxins 137
A*4. Detection limits for PAHs, PCP.
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120
Table A-l. Analytical procedures for soil and water (U. S. EPA 1986a).
Method
Process
number
Compounds
Comments
Extraction of soil samples
3540
All
Use 10 g of soil
Extraction of water samples
3520
All
Use 1000 ml of water
Clean up
3630
All
Done after methyl ation
of phenols
Analysis
8100
PAH's
For polynuclear
aromatic hydrocarbons
Analysis
8040
OCDD+PCP
For chlorinated
phenols after
methyl ation and octa-
chlorodibenzo-p-dioxin;
using an ECD detector
Analysis
8270
All
Check for all compounds
Analysis
8280
Used for low-level
dioxins (penta, hexa,
and hepta dioxins)
Table A-2. Analytical procedures for sludges.
Process Procedure
Water content ASTM D-95-70
Organic content Heating at 600°C for 2 hours in an oxidative
atmosphere
Non-volatile products Heating at 600°C for 2 hours in an oxidative
atmosphere
Oetermined by CO? evolution
Method 222E Standard Methods for Examination
of Water and Wastewater
Method 5030 Standard Methods for Examination
of Water and Wastewater
Micro Kjeldahl followed by digestion with 5%
hydrogen peroxide and sulfuric acid; nitrogen
was determined colorimetrically using
nessierization
Determined after digestion colorimetrically
using the Fisbe-Subarrow method
Determined using a cnloride specific ion
electrode
Organic carbon
Total phenolics
Oil and grease
Nitrogen
Phosphorous
Inorganic chloride
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121
Extraction of PCP. PAH's. and OCDD from Soil
Soil (10 g) was mixed with dry sodium sulfate (10 g). (The sodium
sulfate had been dried at 400°C for four hours and stored in a
desiccator.) The sample was placed in an extraction thimble and 1 ml of
an internal standard in methylene chloride was added. The internal
standard mixture for high levels consisted of 5,000 ppm of
diphenylmethane, 1000 ppm of trlbromophenol, and 21 ppm of octachloro-
naphthalene. For low levels, a 1 to 10 dilution of the internal
standard was used. The extraction thimble was placed in the Soxhlet
unit along with 300 ml of pesticide grade methylene chloride and boiling
chips.
The soil in the Soxhlet unit was extracted for 16 hours with a
minimum recycle rate of 5/hour. The extraction units were cooled and
transferred to a Kuderna-Danish unit and condensed to a volume of
approximately 3 ml.
The condensed extract was diluted to exactly 5 ml and aliquots were
taken for OCDD and PCP and PAH analyses. The remaining solution was
stored in a freezer at -27°C 1n a teflon-lined, screw-cap vial.
Clean-up and Determination of PAH's and PCP in Soil Extracts
S11ica gel was activated at 130°C for 16 hours (100-120 mesh
Davison Chemical Grade 923 or equivalent) 1n a beaker covered with foil.
The silica gel was stored in an air-tight desiccator and redried every
two weeks. The columns (10 mm i.d.) were packed using 9 grams of
activated silica gel. The silica gel was packed into the column with
gentle tapping. The column was pre-eluted with 20 ml of pentane
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122
(pesticide grade or HPLC grade). The pentane was allowed to elute until
the solvent was just above the silica gel. The silica gel was not
allowed to dry before sample addition.
An aliquot of the methylene chloride extract was put in a sample
tube. The exact amount depended on the loading amount of creosote or
the analysis of previous sample. Three ml of sample was added 1f the
loading rate was less than 0.632% (wt/wt) of creosote on soil or if the
previous sample contained less than 6,000 ppm total PAH's.
Diazomethane solution (0.1 ml) was added to the sample tube and
mixed with a vortex mixer. An aliquot was added to the column. If a
1-ml aliquot on column was used, 2 ml of methylene chloride was added to
the column. A 1 to 3 ml allqot of 40% methylene chloride/60% pentane
was added three times to ensure that all the sample is absoroed on the
column. Columns were eluted with 50 ml of the 40/60 mixture and the
eluant was collected. The eluant was concentrated to 5 ml by
evaporation using a gentle stream of dry air or nitrogen and analyzed
using gas chromatography conditions shown below for PAH's.
A 1-ml sample was removed for PCP analysis and stored in a glass
teflon-lined crimp-top vial. This sample had to be diluted for GC/ECO
analysis. The exact dilution depended on the anticipated concentration
of PCP.
Tracor 540 Gas Chromatoqraph Parameters for PAH Analysis
Column: J and W DB-5 fused silica capillary
Length: 30 meters
Film thickness: 1.00 wm
Inside diameter: 0.32 mm
Injector temperature: 325°C
Oven temperature program: 4 minutes to 40°C, then 6°C per minute
for 15 minutes to 325°C
Carrier gas: Helium; Pressure: 12 psi
FIO temperature: 325°C
Hydrogen flow: 60 cc/min
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123
Air flow: 400 cc/min
Nitrogen makeup: 40 cc/min
Injection: 2 yl splitless, vent after 1.5 min.
Amplifier range: xl
Tracor 540 GC Parameter for PCP Analysis
Column: 6 ft x 2 mm i.d. glass packed with 3% SP-2250 on 100/120
mesh supelcoport
Carrier gas: Ar/CH* at 10 cc/min
Injector: 250°C
Oven: 220°C
Detector• 350®C
ECD detector makeup gas: 95% argon/5% methane at 60 cc/min.
Clean-up and Determination of Octachlorodibenzo-p-dioxin in Soil (HSU
1984)
The analysis of 0CDD in soil presented two significant problems
which had to be dealt with in order to obtain reliable results. First,
an extraction procedure had to be used which would be highly efficient
in removing 0CDD from the sample matrix. This was especially important,
since the anticipated concentration of 0CDD in the soil was in the
parts-per-billion range. Secondly, the majority of the compounds which
co-extracted with 0C0D were likely to be several orders of magnitude
higher in concentration than 0C00. A clean-up technique had to be used
which allowed the concentration of 0CDD with minimal chemical
interference.
Method Sunmary—Methylene chloride Soxhlet extraction was found to
be very efficient in the removal of 0CDD from a soil matrix (U. S. EPA
1983). Thus, an aliquot of soil extract from the PAH analysis, which
uses the same extraction procedure, was considered to be adequate and
also would save analysis time. For our purposes, the removal of the
majority of chemical interferences could be accomplished by a
modification of two column clean-up techniques recommended by EPA for
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124
2,3,7,8-TCDO analysis (U. S. EPA 1983). An elution profile and recovery
were determined for this modified column clean-up and were found to be
quite adequate (Mississippi State 1984).
Materials and Supplies-
Basic alumina, type WB-5, Activity Grade I, Sigma Chemical Co. or
equivalent.
Silica gel, 100/200 mesh, Fisher Scientific Co. or equivalent.
5 ml disposable pipet, Scientific Products Co.
Silane treated glass wool, Supelco, Inc.
9" disposable Pasteur pipets, Scientific Products Co.
10 ml graduated cylinder, Pyrex.
Small funnel with a cut latex bulb attachment.
Qisposable 1 ml serological pipet, Scientific Products Co.
Compressed air with regulator and manifold.
Water bath.
Benzene (Burdick and Jackson distilled in glass).
0C00 for standards, Analabs.
Gas chromatograph equipped with ECO and a 6-ft x 2-mm i.d. glass
column packed with 3% SP-2250 on 100/120 mesh supelcoport.
Procedure--
Before use, the silica gel and basic alumina were activated for
16-24 hours at 130°C in a foil-covered glass container.
A small plug of glass wool was placed in the bottom of a 5-ml
pipet.
A funnel with a cut latex bulb attached was placed on the pipet and
2 ml of basic alumina (bottom) and 2 ml of silica gel (top) were
added to the pipet.
The column was pre-rinsed with two 4-ml portions of Benzene which
was then discarded.
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125
A 10-ml volumetric flask was placed under the column. Before
clean-up, the methylene chloride extract was exchanged with
benzene by blowing down the methylene chloride to dryness with
dry air in a 50°C water bath and adding 1 ml of benzene.
The benzene extract was placed on the column.
After the sample extract had flowed into the silica gel layer, 4 ml
of benzene was added to the column.
All of the eluate was collected until the column stopped dripping.
The eluate was diluted to 10 ml with benzene and a 1 ul sample was
injected on the Tracor 540 6C/ECD using the following conditions:
Oven: 280°C; Injector: 330°C; Detector: 350°C
Quality Assurance Program for Soil Extraction and Analysis
Four types of internal checks were used to monitor the accuracy of
the soil extraction and analytical procedures.
Blanks—This control was used to monitor the glassware, solvents,
and the solid supports (silica gel and alumina) background levels. The
blank was processed exactly the same way as the samples except no soil
was used during the Soxhlet extraction. Diphenylmethane, 2,4,6-
tribromophenol, and octachloronaphthalene were added to the extracts as
an internal standard.
Spike Samples—Standard solutions of PAH's, PCP, and OCDD were
prepared using the best standards available (purity « 99X or better) in
methylene chloride. A sample of the standard solution was added to the
soil before Soxhlet extraction. The sample was extracted and cleaned up
using the normal procedures. The values of the spiked sample were used
to determine the recovery values for the individual compounds.
Diphenylmethane, 2,4,6-tribromophenol, octachloronaphthalene were used
as internal standards. All standards were prepared using a Hettler
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126
5-place analytical balance. Each time a standard was prepared, the
weight, date, and standard number were recorded, and the balance was
checked with standard weights (Class S - National Bureau Standards).
Standard Solutions for Gas Chromatography Calibration—A standard
solution of PAH's containing the 16 compounds of interest was prepared.
It contained an internal standard (diphenylmethane). Standard solutions
were also made for the PCP and octachlorodibenzo-p-dioxin and analysis
with the corresponding internal standards 2,4,6-tribromophenol and
octachloronaphthalene. A minimum of three concentration levels was
used for each compound.
Blind Samples—Blind samples containing EPA standard reference
materials (Quality Assurance Branch EMSL-C1ncinnati, U. S. EPA) were
diluted by the Quality Control Officer (Or. Hamid Borazjani) and
analyzed.
QC/MS Analysis—A part of each sludge sample after homogenizing
(approximately 1 gram) was weighed to three significant figures, mixed
with an equal weight of anhydrous sodium sulfate and extracted for 16
hours with 300 ml of methylene chloride in a Soxhlet extractor. The
volume of methylene chloride from each sample was adjusted to 100 ml
with a volumetric flask. A 1.00 ml aliquot of each extract was
transferred to a screw cap test tube and stored at approximately 4°C
prior to GC/MS analysis. The sample weight range and dilution volume
were based on prior knowledge of concentrations determined by GC/FIO
analysis.
The GC was a Carlo Erba fitted with a J and W DB-5 capillary
column [0.25 ym film thickness and 30 m (1) by 0.25 mm (1.d.)].
After sample injection the GC was operated at 70°C for 2 minutes and
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127
then programmed to 280°C at 6 deg/min and from 280° to 320°C at 12
deg/min. The GC oven temperature was kept at 320°C for 20 minutes. The
injector and transfer line temperatures were 320° and 280°C,
respectively.
The mass spectrometer (Kratos MS80RFA) was operated in the electron
impact mode (70 eV) with a source temperature of 250°C. After a 6,0-
minute delay for elution of the solvent peak, mass spectral data were
acquired with a scan rate of 1 sec/dec for 54.0 minutes. Two standard
solutions (10 wg/ml and 200 jig/ml) containing known concentrations of
selected analytes were used to establish Instrument response factors.
The concentration of each compound in solution was reported by the DS-90
data system and the concentration in sludge was calculated as follows:
100 ml x c yg/ml
C yg/g ¦ --
Here, C ¦ concentration of each compound in sludge (jig/g); 100 *
dilution volume, c ¦ concentration of each compound in the sample
extract, and W ¦ dry weight of the sludge sample 1n grams.
Site and Soil-Characterization
Soil profiles were examined at each site in freshly excavated pits
and they were described and sampled using standard methods (Soil Survey
Staff, 1951). Soil morphological descriptions included horizonation,
Munsell color, texture, horizon boundaries, consistency, coarse
fragments, root distribution, concretions and pedological features.
Each horizon was sampled for laboratory analyses. Bulk density was
determined on major horizons using the non-disturbed core method (Blake,
1965). Saturated hydraulic conductivity was determined on non-disturbed
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128
cores using the constant heat method (Klute, 1965)". Soil moisture
retention was determined on non-disturbed cores using a pressure
membrane apparatus (Richards, 1949).
Soil samples were air-dried in the laboratory, crushed with a
wooden rolling pin, and sieved through a 10-mesh sieve to remove
fragments larger than 2 mm (USOA, 1972). Particle size distribution was
determined by the hydrometer method and sieving (Day, 1965). Organic
matter was determined by a wet combustion procedure (Allison, 1935).
Extractable acidity was determined by the barium chloride-
triethanolamine method (Peech, 1965). Exchangeable aluminum was
determined in KC1 extractions following the procedure of Yuan (1959).
Exchangeable cations were extracted with neutral 1 NH4OAC and
determined by atomic absorption spectrophotometry (USDA 1972). Soil pH
was measured in water and 1 N, KC1 using a 1:1 soil-to-liquid ratio.
Electrical conductivity was determined in saturated paste extracts using
a Wheatstone conductivity cell. Total sulfur was determined on soil
samples ground to pass a 60-mesh sieve in a LECO Sulfur Analyzer using
an induction furnace and I.R. detection.
The clay fraction (<2 mm) was separated by centrifugal
sedimentation using Calgon as a dispersing agent. Clays were
K-saturated, Mg-saturated, and glycerol-solvated for x-ray diffraction
analysis. The clay fraction was analyzed with a Norelco Gelger counter
spectrophotometer using Cu K radiation and a Ni filter. Minerals were
identified based on comparison of diffraction spacings and frequencies
to standard minerals as Indicated by Jackson (1956), Carrol (1970), and
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129
Dixon and Weed (1978). Relative estimates of the amounts of clay
minerals present were based on peak area measurements with corrections
o
for Lorentz polarization at peaks greater or equal to 14 A.
Transformation/Degradation Using a Standard Creosote/PCP Mixture:
Experiment I
Wet soil was spread upon a new sheet of plastic and air-dried for
24 hours or longer until the moisture content was reduced. The dried
soil was stored in clean glass containers that had been labeled with the
soil source, the collection day, and a number. A sample of each new
soil was sent to Delta Labs, Inc., for analysis of soil parameters,
nitrogen, phosphorus, organic carbon, and inorganic metals; pH and
chloride ion was determined in-house. The soil was sieved just before
use to remove coarse plant materials from the soil, and the moisture
content was determined. Spiked soil samples were prepared using the
following procedure: Soil samples (50.0 g/beaker) were accurately
weighed Into 10 beakers. Known amounts of creosote and/or technical
grade pentachlorophenol were added into each beaker. Technical grade
PCP was dissolved thoroughly in methylene chloride or methanol before
being added to the soil in the beaker. Then contents of all ten beakers
were combined and mixed for 2 hours in a clean glass jar using a sample
rotator with a minimum of 50 revolutions/minute. The dual procedure for
mixing was found to give more uniformly mixed material. Soil moisture
was adjusted to 70% of water-holding capacity by adding delonized H20
into the soil when mixing was finished. The same mixing procedure was
repeated for controls.
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130
Two test units were set up for each site. One unit was a control
(0%), and one was loaded at IS with the standard creosote/PCP mixture.
Each unit consisted of a brown glass container with a lid (baking dish)
containing 500 g of soil (dry weight). Soil moisture content was
adjusted to 70% of water-holding capacity, and the container's weight
was determined. The accurate weight of the unit was important since
this value was used to maintain a proper moisture content during the
study. The test units were put into a constant temperature room
maintained at 22° +_ 2°C for the duration of the study.
Each test was begun by hand stirring the samples and removing two
separate 20 g samples of soil (air-dry weight) from each of the units.
One sample was used to analyze for PAH's, PCP, and octachlorodibenzo-
p-dioxin using the procedure described in a later section of this
report. The second sample was used for bacterial counts, pH and
chloride ion analysis.
The moisture content of each unit was adjusted weekly to 70% by
adding deionlzed water. The soil was aerated by thoroughly mixing the
total contents of each unit every 7 days.
The first samples were taken after 30 days (20 g dry weight) and
analyzed for PAH's, PCP, and 0CDD. Further samples were taken every 30
days until the experiment was complete.
Soil from sites at Gulfport, Grenada, and Wiggins were loaded
initially and at 30 and 60 days. Soil from sites at Atlanta, Meridian,
and Wilmington were loaded intially and at 30 days, while the soil from
sites at Columbus and Chattanooga were loaded only at day 0. A change
was made in loading frequency because data for several sites indicated
that the bacteria at the sites were readily acclimated with one loading.
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131
Kinetic data needed to calculate the half lives, assuming first order
kinetics, were taken after the final loading and over a 60-120 day
period.
No organic or inorganic additions were made to the soil during the
initial set of experiments. The parameters measured were:
- microbial plate counts
- pentachlorophenol
- major PAH's contained in creosote
The soil microflora were measured using five different media. The
total amounts of bacteria, acclimated bacteria, and fungi were
determined using various media. The same media that were used to count
bacteria (PDA) were amended with creosote (PDA-C), pentachlorophenol
(PDA-P), a combination of creosote and PCP (PDA-PC), and PDA with
antibiotics to count fungi (PDA-AA). Because of the very low counts of
fungi and because their population counts did not change appreciably
during the studies, only the results from the bacteria and acclimated
bacteria are reported.
Transformation/Degradation of Site Specific Sludges: Experiment II
In this phase of the study, three different loading rates in soil
were studied--0.3%, 1.0%, and 3.0%—based on the total dry weight of
solids. A single loading was used instead of multiple loading, and
three replications of each soil and loading rate combination were used.
Chicken manure was added to all soil at 4% by weight. Sludges from
Columbus did not contain PCP, so in order to get information on the
rates of degradation of PCP with this soil type, 128-3000 ppm of PCP
were added to the Columbus soils. The parameters measured were
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132
bacteria, fungi, actinomycetes, acclimated bacteria, pentachlorophenol,
major PAH's in creosote, and octachlorodibenzo-p-dioxin. A control
sample of soil from eachsite which contained no added sludges or PCP was
used as a control for the plate counting procedures and to determine the
background levels of PCP, PAH's, and OCDD. Although technical grade PCP
contains traces of two other series of dioxins, their levels are
extremely low (less than 5% of the octachlorodibenzo-p-dioxin levels).
Because of time and resource restraints, it was not possible to monitor
trace level dioxins as part of this study.
All other experimental methods, with the exception of the addition
of chicken manure to the soil (discussed below) were the same as in
Experiment I.
Rationale for the Addition of Chicken Manure to Soil in the
Degradation/Transformation Studie?
During the course of this series of experiments, the data generated
reemphasized the importance of soil organic matter in facilitating the
microbial transformation of applied organic wastes. Since the ultimate
goal of these studies was to establish an operating landtreatment test
facility, the decision was made to maximize the operating effectiveness
and efficiency of the facility by amending the experimental soils with
an animal manure. This amendment accomplished several objectives. The
manure furnished: (I) a carbon source for potential cometabolism, which
has been found in at least some instances to be an important component
of the transformation process; (2) both major and minor nutrients; and
(3) a wide variety of microbes that were potentially important
biodegraders. Also, added organic matter should markedly decrease
mobility of hazardous constituents in organic applied wastes, which is
highly desirable in a landtreatment operation. Although other animal
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133
manures might serve as well, chicken manure was chosen for study because
it is readily available in many parts of the United States. A typical
analysis of the chicken manure used in this study 1s given below:
Total organic carbon * 8.97%
Total nitrogen * 1.35%
Total phosphorous * 0.12%
A comparison between bacteria counts of four of the soils used in
this study was done before and after manure addition. No PCP or
creosote was added to the soil (0% controls) and the bacteria counts
were determined in soil 30 days after manure loading. The results
(Table A-3) indicate a large increase in both the total bacteria and the
acclimated bacteria in the soil with added chicken manure.
Microbiological Procedures
The media used for this study were potato dextrose agar, POA (Difco
Laboratories, Detroit, Michigan), 39 g 1n one liter of delonized water,
PDA amended with 5 mg/L of technical-grade pentachlorophenol [poa-P]
(Vulcan Materials Company, Wichita, Kansas), PDA amended with 10 mg/L of
whole creosote [PDA-C], PDA amended with a combination of 5 mg/L of
pentachlorophenol and 10 mg/L of whole creosote [P0A-CP], POA amended
with antibiotics—120 mg/L of streptomycin sulfate (Nutritional
Biochemical, Cleveland, Ohio) and 30 mg/L of chlorotetracycline
hydrochloride (Nutritional Biochemical, Cleveland, Ohio) [PDAA], and
actinomyces broth (Difco Laboratories, Detroit, Michigan) £ACA], 57 g in
one liter of deionized water amended with 15 g of Difco agar and 30 mg/L
of Pimricin. The POA was autoclaved for 20 minutes at 15 psi and 121°C
and then cooled to 55°C. Both creosote and pentachlorophenol were
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134
Table A-3. Bacteria levels in four soils at 0% loading before and after
addition of chicken manure3.
Total bacteria counts Acclimated bacteria counts6
(million counts/gram of soil) (million counts/gram of soil)
Site Before addition After addition Before addition After addition
Gulfport
1.13
4.50-7.20
0.07
0.50-0.61
Wiggins
0.41
3.10-4.50
0.12
0.64-2.30
Columbus
1.25
2.80-3.10
0.25
0.14-0.35
Meridian
1.10
3.10-4.20
0.09
0.48-0.92
aThese soils were 0%-loaded, and counts were taken 30 days after addition of
chicken manure.
^Bacteria acclimated to PCP and PAH's.
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135
dissolved thoroughly in methyl alcohol and added to cooled POA. The
antibiotics were added to the cooled liquid medium before pouring into
petri dishes. The pH of the media was adjusted to 6.9 to 7.1 before
autoclaving. Twenty-five ml of POA, PDA-C, POA-P, PDA-CP, POAA, and ACA
were poured into disposable petri plates and were allowed to solidify.
For colony counts, triplicate samples of loaded and non-loaded
soils were air-dried for 24 to 28 hours under a sterilized transfer
hood. The air-dried soil was then screened with a 400 mesh sieve.
Serial dilutions were made by using sterilized screened soil. Three
20-mg soil samples were weighed out from treated and non-treated soil
for each medium at each sampling date. A modified Anderson sampler
(Butterfield et al., 1975, 1977; Warcup, 1950) was used to distribute
the soil on the agar. Three 20-mg samples were distributed over each
medium for each treatment. Colonies were counted after 24 to 48 hours
of incubation at 28°C. A Darkfield Quebec Colony Counter (AO Scientific
Instrument, Keene, New Hampshire) was used to count the number of
colonies on each plate.
The number of counts recovered on PDA plates provided an estimate
of the total number of bacteria per gram of dry soil. On creosote-
containing plates, it represented the approximate number of bacteria per
gram of dry soil that were acclimated to creosote; on PCP-containing
plates, it represented the approximate number of bacteria per gram of
dry soil that was acclimated to pentachlorophenol; on PDA-CP plates, it
represented the approximate number of bacteria per gram of dry soil that
was acclimated to both creosote and pentachlorophenol; on POAA plates,
it represented the approximate number of fungi per gram of dry soil; and
on ACA plates, it represented the approximate number of actinomycetes
per gram of dry soil.
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136
Statistical Procedures
Statistical methods were used to help determine estimates of
compound half-lives and confidence intervals for individual compounds.
Differences in concentration of PCP, PAH, and QCDO between sampling
times were evaluated by calculating a linear regression based on
first-order kinetics. The slope of the regression line was used to
calculate the first-order degradation rates in the soil/sludge mixtures.
The half-life of each compound was calculated from the first-order
degradation rate. The half-life values for the lower and upper 95
percent confidence intervals were also calculated for PCP, PAH, and OCDD
compounds, when waste was applied to soil, to indicate the range of
values about the half-life.
If the slope of the first-order regression was non-negative,
indicating that no treatment by degradation was observed, or if
degradation could not be quantified due to initial low concentration
(near or below detection limit), no degradation information was reported
in the tables.
The microbiological results for the sludges were analyzed using a
complete random design using days as treatments with three replications
and three samples for each replication. Duncan's multiple range test
was used to compare treatment mean differences at (P ¦ 0.05). Oata was
processed using the Statistical Analysis System (SAS) of prepackaged
programs at VIYC (Barr et al., 1979).
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137
Table A-4. Detection limits for soil and sludge,
Sludge
(ppm)
Soil
(PPb)
Naphthalene
2-Methylnaphthalene
1-Methylnaphthalene
Biphenyl
Acenaphthylene
Acenaphthene
Dibenzofuran
Fluorene
Phenanthrene
Anthracene
Carbazole
Fluoranthene
Pyrene
1,2-Benzanthracene
Chrysene
Benzo(a)pyrene
Benzo(ghiJperylene
Pentachlorophenol
17
220
23
290
17
220
18
240
22
280
18
240
21
270
18
230
27
340
26
330
36
460
35
450
37
480
43
560
46
590
47
610
48
620
0.27
27
Octachlorodi benzo-p-
flioxin
0.54
54
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138
SUMMARY
Eight wood treating plant sites were chosen to study the
effectiveness of land treatment for remediation of wood treating wastes.
The morphological, chemical, and microbiological parameters of the soil
at each site were characterized. Typical wood treating waste sludges
from each site were chemically analyzed. Soil samples were taken from
each site to study the rate of microbiological breakdown of wood
treating waste components. In a preliminary experiment, a synthetic
waste was mixed with each soil at 1% of the dry weight of the soil in
order to ascertain waste breakdown rates using the same waste for all
soils. In a second experiment, waste sludge from each site was mixed
with soil from each site at three different loading rates (0.33, 1.0,
and 3.0% by weight). Chicken manure was added to the soils at 4%
weight. The soils were tested at thirty day intervals to determine
microbe populations and amounts of waste compounds remaining.
Degradation rates were calculated for POP, OCDD, and seventeen PAH's.
The general conclusions from this study are that PAH's and PCP are
readily degraded in soil systems. PAH's were transformed easily in all
the soils tested, but PCP was transformed much more quickly in soils
with long term exposure to PCP. Lower molecular weight PAH's and PCP
were usually transformed more quickly than higher molecular weight PAH's
ana PCP. Application of PAH and PCP containing wastes to soil greatly
increases the population of PAH and PCP adapted microorganisms in the
soil. The results of this study indicate that land treatment is an
effective alternative for remediation of PAH and PCP containing wood
treating wastes.
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APPENDIX E
SUPPLEMENTARY MATERIAL FOR PUMP-AND-TREAT TECHNOLOGY
Dr. Joseph F. Keely, Portland, Oregon
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PERFORMANCE EVALUATIONS
OF PUMP-AND-TREAT REMEDIATIONS
by
Joseph F. Keely, Ph.D., P.Hg., FA1C/CPC
Introduction
Large expenditures are made each year to prepare for and operate pump-and-treat remediations of ground-
water contamination. Regulatory responsibilities require that adequate oversight of these remediations be made
possible by structuring appropriate compliance criteria for monitoring wells. The oversight efforts are nominally
directed at answering the question: What can be done to show whether a remediation is generating the desired
control of the contamination or not? Recently, other questions have come to the forefront, brought on by the
realization that pump-and-treat remediations do not function as well as has been presumed: What can be done
to determine whether the remediation will meet its timelines or not? and What can be done to determine
whether the remediation wUl stay in budget or not?
Conventional wisdom has it that these questions can be answered by the use of sophisticated data analysis
tools, such as computerized mathematical models of ground-water flow and contaminant transport. Computer
models can indeed be used to make predictions about future performance, but such predictions are highly
dependent on the quality and completeness of the field and laboratory data utilized. The latter is just as true of
the use of models for performance evaluations of pump-and-treat remediations, in contrast to the common belief
that an accurate performance evaluation can be made simply by comparing data obtained from monitoring wells
during remediation to the data generated prior to the onset of remediation. The eye-opener is that historical
trends of contaminant levels at local monitoring wells art rendered useless by the extraction and injection wells that
are used in pump-and-treat remediations. This is a consequence of the fact that the extraction and injection wells
produce complex flow patterns locally, where previously there were comparatively simple flow patterns.
Complex ground-water flow patterns
present great technical challenges in terms of
characterization and manipulation
(management) of the associated contaminant
transport pathways. In Figure 1, for example,
it can be seen that waters moving along the
flowline that proceeds directly into a pumping
well from upgradient are moving the most
rapidly, whereas those waters lying at the
lateral limits of the capture zone (indicated by
the bold curved line in Figure 1) move much
more slowly. One result is that certain parts of
the aquifer are flushed quite well and others are
remediated relatively poorly. Another result is
that thosepwAously uncontaminated
pontons of the aquifer tit at form the peripheral
bounds of the contaminant plume may become
contaminated by the operation of an
extraction well that is located too close to the
plume boundary, because the flowline pattern
extends downgradient of the well. The latter
is not a trivial situation that can be avoided
without repercussions by simply locating the
Figure 1 Flowline Pattern Generated by an Extraction Well
Ground-water flowlines within the bold curved line are
captured by the well. Prior to pumping the flowlines were
straight diagonals (unbounded).
1
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extraction well far enough inside the plume boundary so that its flowline pattern does not extend beyond the
downgradient edge of the plume, because doing so results in very poor cleansing of the aquifer between the
location of the extraction well and the downgradient plume boundary.
It is not possible to determine precisely where the various flowlines generated by a pump-and-treat
operation are located, unless detailed field evaluations are made during remediation. Consequently, there is a
need for more data to be generated during the remediation (csp., inside the boundaries of the contamination
plume) than were generated during the entire RI/FS process at a rite, and for interpretations of those data to
require much more sophisticated tools. Indeed, it might be successfully argued that in most settings one cannot
begin to make sense of monitoring well data collected during remediation unless a mathematical model is used
to organize and analyze the data.
Monitoring for Remediation Performance Evaluations
Data are collected from monitoring wells during remediation* to comply with the terms of a consent decree
or an administrative order. The key controls on the quality of these data are the compliance criteria that are
selected and the compliance point locations at which those criteria are to be applied. Ideally, the compliance
criteria and the compliance point locations would be selected on the basis of a detailed site characterization to
• i • r ...! ..i.i im kannMltftff. I
nsc
detected.
E? ^a1' Umiu (MCxTaI.^. CoKctouio. Limits
Chemical compliant® cr t M.i ura.er Quality. Hydrodynamic compliance criteria are such things as (i)
(ACL's), Detection Limits, to# tte w^S«edSne, (ii) maintenance San
demonstrated prevention or (iiTwoviding
inward hydraulic gradient at the control criteria include (i) effective implementation of
minimum flow, in a stream. security, id (Hi)
drillin, baiu and «Ker mod.Sng. 1 '
iZZES. of chemical hydrodvnamc, and ajtaMSratiw COtttrol compliance criteria mi|ht be
ropriate for a specific compliance point, depending on its location.
1. Background Compliance Paints
kind of compliance point is located a short distance downgradient of the plume. The
The most wdety^d fand « fl0r b ^aetta areas that may be affected by the
exact location is chosen • portion of the strata through which the plume would migrate if the
remediation, (u) it is m an . tj m incizes the possibility of detecting other actual or potential sources of
remediation failed, andIM be^evanttothefc^t site only). Data pthered there
contaminaUon(e.g.,Kisnotlowca7, ^ofthep|u|ne^remcdial£ion Thc
complknce'Steria typically specified for this kinJrf compliance point are Natural Water Quality (Background)
or Detection limits.
2. Public-Supply Compliance Points
significance of their use is in assuring tne quality 01 wucr ucuvciw «/ mmmiumi^ — u la#i58 ^ sdccu
contaminants associated with the target site. Toe compliance criteria typically specified for this kind of
compliance point are MCL's, MCLG's, and maintenance of existing quality.
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3. Gradient Control Compliance Points
A third kind of off-plume compliance point commonly established is one for determinations of hydraulic
gradients. This kind is comprised of a cluster of small diameter wells that have very short screened intervals, and
is usually located just outside the perimeter of the plume and along a line running between two plume
remediation wells. Water level elevations are measured and used to prepare detailed contour maps from which
determinations of the direction and magnitude of the local hydraulic gradients can be made.
4. (Internal] Plume Compliance Points
Less commonly known is the kind of compliance point represented by monitoring wells located within the
perimeter of the plume. Most of these are installed during the site investigation phase (prior to the
remediation), but others may be added subsequent to implementation of the remediation; they are used to
monitor the progress of the remediation within the plume. These can be subdivided into compliance points
located on-site (within the property boundary of the facility that contains the source of the plume of
contamination), and those located off-site (beyond the facility boundary, but within the plume); the latter kind
assumes that tne plume has migrated beyond the facility boundary.
Because of its proximity to the source of contamination, and the technical infeasibility of complete removal
of the source at many sites, the compliance criteria for an on-site compliance point range from Natural Water
Quality to Alternate Concentration Limits (ACL's) that represent the best that can be aonecost-effectively. In
addition, hydrodynamic compliance criteria are often associated with on-site compliance points; e.g.,
moisture-content determinations may be used to evaluate the effectiveness of a cap in reducing or eliminating
infiltration through contaminated soils in the unsaturated zone. An explicit name for these is on-site plume
compliance point. Similarly, one can refer to the remaining compliance points located within the perimeter of
the plume as off-site plume compliance points. The compliance criteria applied to these tend closer to Natural
Water Quality than is the case on-site, but again are closely tied to technology-driven ACL's; more stringent
criteria are usually appropriate, because the source is not included.
5. Interdependendes of Compliance Point Criteria
As discussed in the preceding paragraphs, each kind of compliance point has a specific and distinct role to
play in evaluating the progress of a remediation. The information gathered is not limited to chemical identities
and concentrations, but includes other observable or measurable items that relate to specific remedial activities
and their attributes. In choosing specific locations of compliance points, and criteria appropriate to those
locations, it is essential to recognize the interdependency of the compliance criteria for different compliance
points. For example, one cannot justify liberal ACL's on-site and have realistic expectations of meeting more
stringent ACL's off-site; the facility boundary will not magically dilute the residual contaminants leaving the
on-site area after the remedial action ceases operation. Similarly, one cannot expect Background Compliance
Points to remain free of contamination if the off-site plume ACL is chosen inappropriately.
In addition to the foregoing, one must decide the following: Should evaluations of compliance data
incorporate allowances for statistical variations in the reported values? If so, then what cut-off (e.g., the average
value plus two standard deviations) should be used? Should evaluations consider each compliance point
independently or use an average? Finally, what method should be to use to indicate that the maximum clean-up
has been achieved? The zero-slope method, for example, holds that one must demonstrate that contaminant
levels have stabilized at their lowest values prior to cessation of remediation - and that they will remain at that
level subsequently, as shown by a flat (zero-slope) plot of contaminant concentrations versus time.
Though fully justified by technical considerations, the economic burden of intensive sampling at compliance
points frequently has been sufficient to undercut attempts to structure appropriate compliance criteria in
ground-water contamination remediations. This unfortunate response probably draws strength from the
perception that the funds used for performance evaluations of remediations ought to comprise a minor portion
of the overall costs, parallel to routine performance audits of industrial wellfield operations. In fact, however,
the driving issue in remediations is public health, and the approach to medical problems - where as much or
more money is often spent on diagnostic tests than is spent on the remedy/operation - offers a more
appropriate parallel. The economic concept that flows freely through these mutually complex issues is that one
cannot expect positive benefits from decisions that are not supported by detailed information.
3
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Contaminant Behavior and Plume Dynamics
Ground water flows from recharge zones
to discharge zones in response to the drop in
fluid pressure along that path. The drop in
fluid pressure may be represented by
water-level elevation contours for ground
water that has a constant density, but must be
represented by water pressure contours for
water having a variable density because fluid _
pressure is created by the combined effects of I
elevation, fluid density, and the acceleration I
of gravity. Additions to the dissolved solids
content of water causes an increase in its
density. For example, synthetic seawater can
be prepared by adding mineral salts to fresh
water. Landfill leachate is often so laden with
dissolved contaminants that its density
approaches that of seawater.
PMTIY \
IftPTVPOMt
Figure 2 Surface Spill of Chemicals from Storage Drums
Spilled fluids initially fill the uppermost soil pores. As much
as half of the fluids remain in each pore after drainage.
As ground water flows through the
subsurface in response to pressure
differences, or gradients, it dissolves some of
the materials it is brought into contact with
viruses and^maU badefflSs to natural water quality 7 a combiwd dbemiad, biological, and
u„i.7.#«.«,, m«u he suitable for man's uses. Brines and brackish waters are examples where
Li jx^r^idu., o, ptou ri..
rm^dhim fn^olcmiallv detractive interactions between contaminants and subsurface formations, sucE as the
ton 01 umesione ano w primary focus of most hazardous waste site cleanups. This fact is
ZSSSS^SSSSSbSSiSSSt ROD', th* 1 fcr pomp-and-trcs* remedUtas.
The mechanism by which a source
introduces contaminants to ground water has
a profound effect on the duration and area!
extent of the resulting contamination. Surface
spills are often attenuated over short
distances (Figure 2), by the moisture
retention capacity of surface soils. By
contrast, there is much less opportunity for
attenuation when the contaminant is
introduced below the surface, such as occurs
through leaking underground storage tanks,
injection wells, and septic tanks.
OREAT HYDRAULIC MPACTS
FROM MK3H RATES OP RELEASE
m———nn—ma—
Figure 3 Hydraulic Impacts of Contaminant Sources
Injection wells and surface impoundments may release fluids
at a high resulting in local mounding of the water table.
Many sources release fluids too slowly to cause mounding.
The hydraulic impacts of some sources of
ground-water contamination, especially
Injection wells and surface impoundments,
nay Impart a strongly three-dimensional
character to local flow directions. The water-
table mounding that takes place beneath
surface impoundments (Figure 3), for
instance, is often sufficient to reverse ground-
water flow directions locally (so that
previously upgradient areas are no longer
4
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upgradient) and commonly results in
much deeper penetration of
contaminants into the aquifer than
would otherwise occur. Interactions
with streams and other surface water
bodies may also impart
three-dimensional flow characteristics
to contaminated ground-water (e.g., a
losing stream creates local mounding
that forces ground-water flow
downward). Ia addition, contaminated
ground-water may move from one
aquifer to another through a leaky
aquitard, such as a tight silt layer that
is sandwiched between two sand or
gravel aquifers.
As ground water moves,
contaminants are transported by
advection and dispersion (Figure 4).
Advection, or velocity, estimates can
be obtained from Darcy's Law, which
states that the amount of water flowing
through porous sediments is found by
multiplying together values of the
travel by advection alon*
additional apraadho eaut«d by dispersion
Figure 4 Bird's-eye View of Contaminant Plume Spreading
Advection causes the majority of plume spreading in most cases.
Dispersion adds only marginally to the spreading.
hydraulic conductivity of the sediments, the cross-sectional area through which flow occurs, and the hydraulic
gradient along the flowpath through the sediments. The hydraulic conductivities of subsurface sediments vary
considerably over small spaces. It is primarily this spatial variability in hydraulic conductivity that results in a
corresponding distribution of flow velocities and contaminant transport rates.
The plume spreading effects of
spatially variable velocities can be
confused with dispersion (Figure 5), if
the details of the velocity distribution
are not adequately known. Dispersion
results from the combination of
mechanical and chemical phenomena
that cause spreading of contaminants
at a microscopic level. The
mechanical component of dispersion
derives from velocity variations among
water molecules trayelling through the
pores of subsurface sediments (e.g.,
the water molecules that wet the
surfaces of the grains that bound each
pore move little or not at all, whereas
water molecules passing through the
center of each pore move most
rapidly) and from the branching of
flow into the accessible pores around
each grain. By contrast, the chemical
component of dispersion is the result
of molecular diffusion. At modest
ground-water flow velocities, the
chemical (or diffusive) component of
dispersion is negligible and the mechanical component creates a small amount of spreading about the velocity
distribution. At very slow ground-water flow velocities, such as occurs in clays and silts, the mechanical
component of dispersion is negligible and contaminant spreading occurs primarily by molecular diffusion.
Figure S Cross-sectional View of Contaminant Plume Spreading
Permeability differences between strata cause comparable differences
in advection and plume spreading.
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In some geologic
settings, most of tbe ground-
water flow occurs through
fractures in rock formations
that have very low
permeabilities. The flow in
the fractwes often responds
quickly to rainfall events and
other fluid inputs, whereas
the flow through the bulk
matrix of the rock is
extremely slow - so slow
that contaminant movement
by molecular diffusion may
be much quicker by
comparison.
On the other end of the
ground-water flow velocity
spectrum is the flow in karst
aquifers, since it may occur
mostly through large
channels anacaverns. In
these situations, ground-
water flow is often turbulent,
and the advection and
dispersion of dissolved
contaminants are not
SETTING
Porous Media
Fractured Rock
Karat Terrain
CONCEPT
Darcy'e Law
Cubic Law
HAGEN-PolseuHe
(laminar pipe flow)
Manning's Formula
(opan channel flow)
FORMULA
O ¦ k A J[_dh
fi dL
Q-C8bAh
7
O ¦ ITr4 ft dh
8 H dL
A R^'S"'
pwure 6 Ground-Water Flow Laws and Equations for Various Settings
Porous media flow is understood best. Then is little consensus on how to
conceptualize and measure flow in fractured rock and karst aquifers.
contaminants are not , .. ^ ,
adequately describabie by Darcy*s Law and other porous media concepts. Dye tracers have been used to s
contaminant transport in fractured rock and karst aquifers, but such studies have yet to yield relationships
(Figure 6) that can be transferred from the study site to other sites.
study
% 3*
PCE
Parent 1
/C "
1
ci a
~
cl 9'
TCE
Daughter 1 Parent 2
/C-cN
|
a h
~
o
/—
vx
DCE
Daughter 2 Parent 3
c-c^
|
h a
~
d p
Vinyl Chloride
Daughter 3
C"C
/ \
H H
Figure 7 Biotransformation of PCE to TCE, DCE and Vinyl Chloride
Biotransformation of PCE (suspected carcinogen, moderate retardation) may
yield vinyl chloride (proven carcinogen, nearly water-coincident transport).
Regardless of the character of
ground-water flow,
contaminants may not be
transported at the same rate as
the water itself. Interruptions
in contaminant movement
occur as a result of sorption,
ion-exchange, chemical
precipitation, and
biotransformation. The
movement of a specific
contaminant may be halted
completely by precipitation or
biotransformation, because
these processes alter the
chemical structure of the
contaminant. Unfortunately,
the resulting chemical structure
may be more toxic and more
mobile than the parent
compound (Figure 7), such as
in the case of anaerobic
degradation of
tetrachloroethene (PCE).
-------
Sorption and ion-exchange
(Figure 8), conversely, are completely
reversible processes that release the
contaminant unchanged after
temporarily attracting it to a solid
surface. This effect is commonly
termed retardation and is quantified by
projecting or measuring the mobility
of the contaminant relative to the
average flow velocity of the ground
water. Projections of retardation
effects on the mobility of contaminants
are based on equations that
incorporate physical (e.g., bulk
density) and chemical (e.g., partition
coefficients) attributes of the real
system. Direct measurement of the
effective mobility of contaminants can
be made by observations of plume
composition and spreading over time.
Alternatively, samples of soils or
sediments from the contamination site
may be used in laboratory studies to
determine the effective partitioning of
contaminants between mobile (water)
and immobile (solids) phases.
Figure 8 Retardation of Metals by Ion Exchange
Metal ions carrying positive charges are attracted to negatively charged
surfaces, where they may competatively replace existing ions.
Retardation effects can be short-circuited by facilitated transport, a term that refers to the combined effects
of two or more discrete physical, chemical, or biological processes that act in concert to materially increase the
transport of contaminants. Examples of facilitated transport include particle transport, cosolvation, and phase
shifting.
Particle transport (Figure 9)
involves the movement of
colloidal particles to which
contaminants have adhered by
sorption, ion-exchange, or
other means. Contaminants
that otherwise exhibit moderate
to extreme retardation may
transport far greater distances
than projected according to
their nominal retardation
values.
Pumping removes a great deal
of colloidal particles, and much
larger particles, from the
subsurface (as witnessed by
many well owners). This fact
can complicate remediations,
and is also relevant to public
water supply concerns.
Figure 9 Contaminant Transport Facilitated by .Colloidal Particles
Sorption of organics (e.g., PCB's) or precipitation of metals (e.g., Pb) onto
colloidal particles may be effective in increasing their transport.
-------
Cosolvation is
the process by which
the solubility and
mobility of a
contaminant are
increased by the
presence of another
contaminant, usually
a solvent present at
percent levels. Such
phenomena are most
likely to occur close
to contamination
sources, where the
concentrations are
typically highest.
Treatment design
strategies should thus
anticipate the need to
remove normally
immobile orgamcs
from ground water
that has been
extracted in areas
close to the source of
contamination.
Health risk
estimates, also,
should factor in the
increased mobility
\pcbJ
Figure 10 Conceptualization of Facilitated Transport by Cosolvation
HMtly insoluble contaminants may dissolve in pound water containing an
solvent, if the solvent is present at a hitft concentration (e.g., percent levels).
organic
UI(.i«Oa«U UIUUHU; |
and exposure potential generated by cosolvation.
>0
Figure 11 Facilitated Transport by Phase Diagram Shifts (e.g. Iron)
Releases of acidic contaminants, or depletion of oxygen by biota, may solubilize
precipitated metals (e.g., iron). Neutral organic compounds also may ionize.
Shifts between chemical
phases (Figure 11) involve
a large change in the pH or
redox (reaction) potential
of water, and can increase
contaminant solubilities
and mobilities by ionizing
neutral compounds,
reversing precipitation
reactions, forming
complexes with other
chemical species, and
limiting bacterial activity.
Phase shifts may occur as
the result of biological
depletion of the dissolved
oxygen normally present in
ground water, or as the
result of biological
mediation of oxidation-
J reduction reactions (e.g.,
¦ oxidation of iron II to iron
111). Phase shifts may also
result from raw chemical
releases to the subsurface.
8
-------
Some ground-water
contaminants are
components of immiscible
solvents, which may be
either floaters or sinkers
(Figure 12). The floaters
generally move along the
upper surface of the
saturated zone of the
subsurface, although they
may depress this surface
locally, and the sinkers
tend to move downward
under the influence of
gravity (Figure 13V Both
kinds of immiscible fluids
leave residual portions
trapped in pore spaces by
wetting tension. This is
particularly troublesome
when an extraction well is
utilized to control local
gradients such that free
product (the (trainable
gasoline) flows into its
cone of depression; the
fmmlsclbl* misclbl*
gatoBn*
a*.-
,
Figure 12 Immiscible and Miscible Contaminant Plumes
Gasoline is an immiscible (insoluble) floater, whereas PCE is an immiscible sinker.
Methanol is a totally miscible floater, whereas brines are highly miscible sinkers.
adversity is that the cone of depression will contain trapped residual gasoline below the water-table (Figure 14),
which will become a continuous source of contamination, and which will persist even when the extraction well is
turned off.
floater movement controlled
by the gradient
^4* "fad" ^ «W-«l
IK
¦ ' • #-i
-i «
¦ *•
Ideal depression of waterli^&^Sft
table by bulk effect Sgy&ggS#
•inker movement Is
gravity controlled
Tt. 1¥1- I * ' ™'v T " - -
.filllliillils'lfx
:S4t^mmSSSSS.^k:!^:'t.
GROUND WATER
MOVEMENT
Figure 13 Dynamics of Floater and Sinker Plumes
Bouyant phones migrate laterally on tap of the water saturated zone. Dense plumes
sink and follow bedrock slopes, which may oppose ground-waterflow directions.
Reliable prediction
of the future movement
of contaminant plumes
under natural flow
conditions is difficult
because of the need to
evaluate properly the
many processes that
affect contaminant
transport in a particular
situation. Remediation
evaluations are even
more difficult because
of extensive redirection
of pre-remediation
transport pathways by
pump-and-treat
wellfields. Hence, in
terms of preparations
for remediation, it is
most important to
determine the
permeable pathways
(where the ground
water can go) during the
site investigation.
9
-------
Ffsnre 14 Zone of Contaminant Resiuu«*> ^ - —r~e, ....
n??n w*lt Bumping cnates a cone of depression to trap gasoline for removal by skimmer
^mpTbu^Tso mates a zone of contaminant residuals below the water table.
Design and Analysis Complications
treat remediations. N^hcr » actively manipulated by the pumping wells). Consequently, monitoring
zo,« cfjacnjfitalLSSSdTtoffiwdS r.pii worxlfc cluraii. !!» qui*, of pound ™ter « .ny
strategies must be cognizanlt ^ means that tracking the effectiveness of pump-and-treat remediations
spcdlfc point inthe> zoneJ ^ Ke™ Decisions regarding the frequency aid demity of chemical
by chemical samplings is qu fl {^ greaerated by the remediation wellfield, including changes in
samplings must confer toe det^^^ in the influences of transport processes Jong those
contaminantconcentratiOTS occasionally, to remediate portions of the contaminated zone
flowpaths. f slow flowlines, means that the chemical samplings may generate results that are
122* b. «««..»» U» cofpliu.ee ,-mtt totag ,he
course of a remediation.
plished. For
t contaminant
posed to
performance
i.. mHisnt must dc mcasureu ™ »¦"»'¦»«¦ wvm bum pair of
_ __ jly, the Mrauucgr ^ jj,e fc$\gn 0f an array of piezometers (small diameter wells with very short
adjacent pumping °r "JJ"* . measurc the pressure head of selected positions is as aquifer) for this
screened mt^ that arc ^ to mew^^ p Twq ^ points define a planar
purpose a " needcdt0 define the convoluted water-table surface that develops between adjacent
surface; but Not only are there velocity divides in the horizontal dimension near active wells, but
F— of ««* «» and. ,o od, . hM dep* ta
practical terms.
10
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Limitations of Pump-and-Treat Remediations
Conventional remediations
of ground-water contamination
often involve continuous
operation of ao
extraction-injection wellfield.
In these remedial actions, the
level of contamination
measured at monitoring wells
may be dramatically reduced in
a moderate period of time, but
low levels of contamination
usually persist. In parallel, the
contaminant load discharged by
the extraction wellfield declines
over time and gradually
approaches a residual level in
the latter stages (Figure 15).
At that point, large volumes of
water are being treated to
remove small quantities of
contaminants. Depending on
the reserve of contaminants
within the aquifer, this may
cause a remediation to be
continued indefinitely, or it may
lead to premature cessation of
the remediation and closure of
OFF
MAX
0 -
RESIDUAL
CONTAMINATION
\
TIME
Figure IS Apparent Clean-up by Pump-and-Treat Remediations
Contaminant concentrations in pumped waters decline overtime during pump-
and-tnat remediations, to an apparently irreducible level.
the site. The latter is particularly troublesome because an increase in the level of ground-water contamination
may follow (Figure 16) if the remediation is discontinued prior to removal of all residual contaminants.
OFF
MAX
/y\rjs j // ;r>
There are several contaminant
transport processes that are potentially
responsible for the persistence of
residual contamination and the kind of
post-operational effect depicted in
Figure 16. In order to generate such
effects, releases of contaminant
residuals must be slow relative to
pumpage-induced water movement
through the subsurface. Transport
processes that generate this kind of
behavior during continuous operation
of a remediation wellfield include:
Figure 16 Contaminant Rebound After Pump-and-Treat Ceases
Contaminant concentrations may rebound when pump-and-treat
remediations cease, because of contaminant residuals.
diffusion of contaminants within
spatially variable sediments,
hydrodynamic isolation,
sorption-desorption, and
liquid-liquid partitioning.
11
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LOW PERMEABILITY
STRATA j i
1. Advection vs. Diffusion
Variations in rates of
advection (flow velocity) that
are caused by spatial variability
of hydraulic conductivity result
in rapid cleansing of higher
permeability zones by
extraction wellfields, because
these sediments conduct
virtually all of the flow. By
contrast, it is only by the
process of chemical diffusion
that contaminants are removed
from the low-permeability
sediments, and the rate at
which that occurs is dependent
on the difference in
contaminant concentrations
within and external to the low
permeability sediments (Figure
17). Hence, when the higher
permeability sediments are
cleaned up, the strength of
chemical forces drawing
contaminants from the Tower
permeability sediments is at its
greatest and is exhausted only
when the chemical
concentrations are nearly equal everywhere (or, at least, grade from greater to lesser such that no sharp
differences exist). The orders-of- magnitude greater surface area of the low-permeability sediments allows
— fn Accumulate on them durins the oollution event /activity i
Figure 17 Variations in Permeability Limit Pump-and-Treat Effectiveness
High permeability sediments conduct virtually all of the flow; low permeability
sediments act as slowly leaking contaminant reservoirs.
differences exist). The orders-oi- magnuuue ----- —~ -r- r- ~-v ;7
signified greater amoutt. of coMmtoU .0 Kc.mn.ly. o. torn dumgfe poa.uo^j/.ctmty. m
contrast to much lower accumulatiom c0?tam"™*5 ™ ,!L
permeability stratum, the more contaminant reserves it can hold, and the more diffusion controls contaminant
movement overall. Hence, the majority of contaminant reserves may be available anhr under
diffusion-controlled conditions in many
acdonjaw^torom^inM^in lowpermeabiSty sediments is restricted to that provided by diffusion.
2. Hydrodynainlc Isolation
luifer results in the formation of stagnation zones downgradient
from
The operation of any wellfield in a moving aauiferrc!
of extraction wells and upgradient of injection wells. The
the remainder of the aquifer, so mass transport within the ——„ ¦— / — ,
remedial action wells are located within the bounds of a contaminant {Hume, such as for the removal of
contaminant hot-spots, the portion of the plume lying within their associated stagnation zones will not be
effectively remediated. The flowline pattern must be altered radically, by major chances in the locations of
pumping wells, or by altering the balance of flowrates among the existing wells, or both, if the original stagnation
zone(s) are to be remediated. Another form of hydrodynamic isolation is the physical creation of enlarged zones
of residual hydrocarbon (Figure 14) that result when deep welts are used to create cones of drawdown into which
underground storage tank and pipeline leaks of gasoline can flow, so that skimmer pumps can remove the
accumulated product. When the deep water pump is turned off, the water table will rise to its pre-pumping
position which will allow the rising aquifer waters that fill the cone of depression, and any subsequent ground-
water flow through the former cone of depression, to become highly contaminated with BTEX compounds (e g
benzene, the ethyl benzenes, toluene, and the xylenes) as a result of contact with the gasoline remaining on the
aquifer solids (gasoline in residual saturation typically occupies from 20 to 40 percent of tUPpore space of the
sediments).
12
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3.. Sorption Influences
ADVECTION
^ORGANIC CARBON OR
MINERAL OXIDE SURFACE
EQUIL CONC.
For sorbing compounds,
the number of pore volumes to
be removed depends not only
on the sorptive tendencies 01
the contaminant but also on
whether ground-water flow
velocities during remediation
are too rapid to allow
contaminant levels to build up
to equilibrium concentrations
locally ^Figure 18). If
insufficient contact time is
allowed, the affected water is
advected away from sorbed
contaminant residuals prior to
reaching equilibrium and is
replaced by fresh water from
upgradient. Hence, continuous
operation of pump-and-treat
remediations results in steady-
state releases of contaminants
at concentration levels that may
be substantially lower than
their corresponding
equilibrium levels. With less
contamination being removed
Ecr each volume of water
rought into contact with the
affected sediments, it is clear
that large volumes of mildly
contaminated water are
recovered, where small
volumes of highly contaminated
water would otherwise be
recovered.
Unfortunately, this is all
too likely too occur with
conventional pump-and-treat
remediations (and with those
in-situ remediations that
depend upon injection wells for
delivery of nutrients and
reactants), because ground-
water flow velocities within
wcllflelds are many times
greater than natural (non-
pumping) flow velocities, and increase exponentially with decreasing distance to the pumping locations. Hence,
depending on the sorptive tendencies of the contaminant, the time to reach maximum equilibrium
concentrations in the ground water may simply be too great compared with the average residence time in transit
through the contaminated sediments.
SLOW
DE80RPTI0N
MITIAL RAPID
OESORPTION
TIME
Figure 18 Sorption Limitations to Pump-and-Treat Effectiveness
Increased flow velocities caused by pumpage may not allow ground-water
contaminant concentrations sufficient time to reach maximum levels.
13
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4. Uquid-UqukJPartitioning
When
immiscible or non-
aqueous phase
liquid (NAPL's) are
trapped in pores by
surface tension to
the surrounding
sediment grains,
diffusive liquid-
liquid partitioning
controls dissolution
of these NAPL
residuals into the
ground water.
Similar to the
process with sorbing
compounds, flow
rates during
remediation may be
too rapid to allow
aqueous saturation
levels of partitioned
contaminants to be
reached locally
(Figure 19). If
insufficient contact
time is allowed, the
affected water is
advected away from
the NAPL residuals
prior to reaching
chemical
equilibrium and is
replaced by fresh
water from
upgradient.
Again, this
process generates
large volumes of
mildly contaminated
water where small
volumes of highly
contaminated water
would otherwise
result, and this
means that the
remediation will
pump and treat far
more water than
would otherwise be
the case. The a
efficiency loss is
v i T www
J
LIQUID-LIQUID
PARTITIONING
Z
o
F
<
0C
H
Z
uj
o
z
o
o
SOLUBILITY
LIMITED
DIFFUSION
LIMITED
GROUND-WATER VELOCITY
Figure 19 Liquid Partitioning Limitations of Pump-and-Treat Effectiveness
Increased flow velocities caused bymunpage may not allow ground-water contaminant
concentrations to reach maximum levels (same limitations as for sorption).
ciiiciency lossu
i Sssr' ^ »bdow«.
14
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Innovations in Pump-and-Treat Remediations
One of the promising innovations in pump-and-treat remediations is the idea of intermittent operation of a
remediation wellfield, termed pulsed pumping. Pulsed operation of hydraulic systems is the cycling of extraction
or injection wells on and off in active and resting phases (Figure 20). The resting phase of a pulsed-pumping
operation can allow sufficient time for contaminants to diffuse out of low permeability zones and into adjacent
high permeability zones, until maximum concentrations are achieved in the higher permeability zones; or, for
sorbed contaminants and NAPL residuals, sufficient time can be allowed for equilibrium concentrations to be
reached in local ground water. Subsequent to each resting phase, the active phase of the pulsed-pumping cycle
removes the minimum volume of contaminated ground water, at the maximum possible concentrations, for the
most efficient treatment. By occasionally cycling only select wells, their stagnation zones may be brought into
active flowpaths and remediated.
Pulsed operation of
remediation wellfields
incurrs certain
additional costs and
concerns that must be
compared with its
advantages for
sile-specific
applications. During
the rest phase of pulsed-
pumping cycles,
peripheral gradient
control may be needed
to ensure adequate
hydrodynamic control of
the plume. In an ideal
situation, peripheral
gradient control would
be unnecessary. Such
might be the case where
there are no active
wells, major streams, or
other significant
hydraulic stresses
nearby to influence the
contaminant plume Figure 20 Reduction of Residual Contaminant Mass by Pulsed Pumping
while the remedial Repeated removal of highly contaminated pound water pulses ensures effective
action wellfield is in the depletion of contaminant residuals.
resting phase. The
plume would migrate only a few feet during the tens to hundreds of hours that the system was at rest, and that
movement would be rapidly recovered by the much higher flow velocities back toward the extraction wells during
the active phase.
When significant hydraulic stresses are nearby, however, plume movement during the resting phase may be
unacceptable. Irrigation or water-supply pumpage, for example, might cause plume movement on the order of
several tens of feet per day. It might then be impossible to recover the lost portion of the plume when the active
phase of the pulsed-pumping cycle commences. In such cases, peripheral gradient control during the resting
phase would be essential. If adequate storage capacity is available, it may be possible to provide gradient control
in the resting phase by injection of treated waters downgradient of the remediation wellfield. Regardless of the
mechanics of the compensating actions, their capital and operating expenses must be added to those of the
primary remediation wellfield to determine the complete cost.
Pump-and-treat remediations are underway today that incorporate some of the principles of pulsed
pumping. ^ For instance, pumpage from contaminated bedrock aquifers and other low permeability formations
results in intermittent wellfield operations by default; the wells are pumped dry even at low flow rates. In such
15
-------
cases the wells arc operated on-demand with the help of fluid-level sensors that trigger the onset and cessation
of pumpage. This simultaneously accomplishes the goal of pumping ground w*er only after it has reached
chemicil equilibrium, since equilibrium occurs on the same time frame as the fluid recharge event (both are
diffusively restricted)! In settings of moderate to high permeability the onset and cessation of pumpage could be
keyed to Lntaminant concentration levels in the pumped water independent of flow changes required to
main tab ototct hydrodvnamic/gradient control As indicated in the discussion of pulsed pumping, this could be
Kdto EJSptablc (pose no unreasonable risk) in circumstances where the contaminant plume would not be
subject to substantial movement in the absence of pumpage.
Other strategies for improvement of the performance of pump-and-treat remediation* include:
m flow scheduling of wellfield operations to satisfy simultaneously hydrodynamic/gradient control and
concentration trends or other performance criteria,
(2) physical repositioning of extraction wells to effect major flowline/transport pathway alterations, and
(3) integration of wellfield operations with other subsurface technologies (e.g., barrier walls to limit
Sume transport and minimize pumping of fresh water; or, infiltrationi ponds to maintain saturated
flewconditions for flushing contaminants from [normally] unsaturated soils and sediments).
Th- rjret Of these bv itself would allow for flushing of stagnant zones by occasionally turning ofT individual
lumlc hnl n.Sinff could not be done as efficiently as when repositioning or addition of pumping wells is
pumps, but ^flushing coul^toea first md xcoud approaches differ b effects, however,
access for Mta-pred,«ta c**ing o the site
by isolation of the conUun pnrtuMtclv vacuum extraction of contaminanted air/vapor from soils and
removed from thetypical ate. ^^SeSS means of removing VOCs (voliile organic carbon
subsoils evaluated for removal of the more retarded organics, and in-situ chemicai
compounds), steam floodmg u£eing° of metals wastes. Vacuum extrEnhas been shown to be
fixation techniques are beingto ug» ^ ^ VQCs readily ^ ^ ^
capable ofremoving yOCs fromcomparable volumes of contaminated ground water typically
gas/vapor), whereas ^.S'"PP"{£ vams 0f VOCs per day (because VOCs are so poorly soluble in water),
results in the °h*!___ to be an economically attractive means of concentrating contaminant
Similarly, ^eiunfloodig j d body of steam. Regardless of the efficacy of vacuum extraction, steam
residuals, as a front eadmgthe md complete remediation of the contamination in the
flooding 01-dMwri.^SeKential for conttol of fluid and contaminant movement in the
unsaturated zone, they' ea considerU as potentially significant additions to the list of source control
rainwater in the absence of a multilayer RCRA-style cap.
poses major . JwJeauent extraction of the chemical residues on the solids, is the only direct means
1","' accrues:
rcmedialMM cm M bad »¦ 0r coruaminotion, not simply waking in isolation for eventual breakdown of a
fit mb true remediatloBi not just itabilized problema - It b dear that
innPo™tS2SSSd'ieat remediation, and soura removal tednlque. may be tbe mott economical and
responsible choices for remediations henceforward.
16
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Modeling as a Performance Evaluation Technique
Subsurface contaminant transport models incorporate a number of theoretical assumptions about the
natural processes govening the transport and fate of contaminants. In order for solutions to be made tractable,
simplifications are made in applications of theory to practical problems. A common simplification for wellfield
simulations is to assume that all flow is horizontal, so that a two dimensional model can be applied, rather than a
three-dimensional model (which is much more difficult to create and more expensive to use). Two-dimensional
model representations are obviously not faithful to the true complexities of real world pump-and-treat
rcmediations since most of these are in settings where three dimensional flow is the rule (e.g., water-table
aquifers which change significantly in saturated thickness when pumped). Moreover, most pump-and-treat
retnediations utilize partially penetrating wells, which effect significant vertical flow components, whereas the
two-dimensional models assume that the remediation wells are screened throughout the entire saturated
thickness of the aquifer (and therefore do not cause upconing of deeper waters).
Besides the errors
that stem from
simplifying assumptions,
applications of
mathematical models to
the evaluation of pump-
and-treat remediations
arc also subject to
considerable error in
practical situations
where the study site has
been characterized
inadequately. It is
absolutely essential to
have appropriate field
determinations of
natural process
parameters and
variables (Figure 21),
because these
determine the validity
and usefulness of each
modeling attempt.
Errors arising from
inadequate data are not
addressed properly by Figure 21 Grid of Points Evaluated by a Contaminant Transport Model
mathematical tests such Known values of head (h), aquifer storage (S) and transmissivity (T), and other
as sensitivity analyses or inputs are used to predict concentration (C) changes at each gid intersection (node).
by the application of
stochastic techniques for estimating uncertainty, contrary to popular beliefs, because such tests and stochastic
simulations assume that the underlying conceptual basis of the model is correct. One cannot properly change
the conceptual basis (e.g., from an isolated aquifer to one that has strong interaction with a stream or another
underlying aquifer) without data to justify the change. The high degree of hydrogeological, chemical, and
microbiological complexity typically present in Held situations forces one to seek site-specific characterization of
the influences from various natural processes, by detailed Geld and laboratory investigations.
Hence, both the mathematics that describe models and the parameter inputs to those models must be
subjected to rigorous quality control procedures. Otherwise, results from field applications of models are likely
to be qualitatively, as well as quantitatively, incorect. It should be noted that these comments are particularly
germue to pump-and-treat remediations, since the wide distribution of flow velocities (e.g., Figure 1) and the
associated transport of contaminants along the flowtines generated within a remediation wellfield represent the
most complex situations ever modeled in ground-water science. If done properly, however, mathematical
modeling may be used to organize vast amounts of disparate data into a sensible framework that will provide
realistic appraisals of which parts of a contaminant plume are being effectively cleansed, when the remediation
17
C - ? K - 668 ft./day
h • 565 ft p ¦ density
S - .0005 DOC - 1 mg/L
T - 5X 10 gaL/day/ft
municipal
wellfield
J'
)
/ /
i
/
/
/
/
/
y
!
-------
will meet target contaminant reductions, and what to expect in terms of irreducible contaminant residuals
Models may also be used to evaluate changes in design or operation, so that the most effective (all portions of the
contaminated zone impacted) and efficient (the least volume pumped /minimized total costs) pump-and-treat
remediation can be attained.
The author i> leading two research projects funded by EPA's Office of Research and Development, the
Remediation Performance project at RSKERL/Ada and the Pulsed Pumping project at RREL/Cuicinnati, that
are well on the way to providing worked examples of the use of models for performance evaluations and
improved remediation wellfield operations, respectively. Technical reports/publications are due from both
projects by the end of FY89 (30 September 1989). When available, those reports will be used to update this
document.
Other Data Analysis Methods for Performance Evaluations
Mathematical models are by no means the only methods available for use in evaluating the performance of
pump-and-treat remediations. Two other major fields of analysis are statistical methods and graphical methods.
The potential power of statistical methods has been tapped infrequently in ground-water contamination
investigations, save for their limited use in quality assurance protocols. The worthwhile uses are many, however,
as shown in Tabic 1.
Analysis of Variance (ANOVA) Techniques
ANOVA techniques may be used to segregate effort due to chemical analyses
from those errors that are due to sampling procedures and from the intrinsic
variability of the contaminant concentrations at each sampling point.
Owrelation Coefficients
Correlation coefficients can be U«d to provide jnatificatlon for lumping various
• chemicals together (e^ total VOCl), or for wing at^echemkal as a class
>> representative, or to link sources by similar cfcefefcal behivkr. ~ "
•• , * s
Rftgrffftrio*1 ftmrtin«i|.
'' p rgrf ffinn equations may be used to predict contaminant loads based on historical
. ; records and supplemental data, and may be used to test cause-and-effect
hypotheses about sources and contaminant releate rate*. ^ ¦
Surface Trend Analyst! Techniques
Surface trend analysis techniques may be used to identify recurring and
intermittent (e.g- seasonal) trends in contour map* of ground-water level* and
v; contaminant distributions, which may be extrapolated to source locations or future
plume trajectories.
Table t Statistical Methods Useful to Performance Evaluations of Remediations
Based on progress made thus far in the Remediation Performance project, can be concluded that while data
interpretation and presentation methods vary widely, moat site documents tack statistical evaluations and manv
tend to simplify datasets by inappropriate grouping or averaging of the data. '
18
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Graphical methods h
of data presentation and
analysis have been
utilized heavily in both
ground-water flow
problems (e.g., flowline
plots and flownets) and
water chemistry
problems (e.g, Stiff kite
diagrams, Piper trilinear
diagrams, chemical
distribution diagrams).
Figure 1, for example is H
a flowline plot for a
single well. From
analysis of such plots, it
is possible to estimate
the number of pore
volumes that will be
removed over a set
period of time of
constant pumpage, at
different locations in the
contaminant plume.
Figure 11 is a chemical IL=l
phase diagram for iron, Figure 22 Pie-Chart Representation of Major Ions in a Ground-Water Sample
which may be used to The milli-equivalence values of each major ion are computed and plotted to generate
relate pH and redox easily identified patterns specific to the water source.
measurements to the
most stable species of iron.
Figure 22 represents one means of
producing readily recognizable
patterns of the major ion composition
of a water sample, so that it may be
differentiated from other water types
(such as natural background quality vs.
contaminated waters). Similarly,
Figure 23 represents another means of
producing readily recognizable
patterns of the milli-equivalence values
of the major ions (related to their
chemical reactivity) of a water sample.
These graphical presentation
techniques have been adapted recently
to the display of organic chemical
contaminants. For example, a
compound of interest such as
trichloroethene (TCE) may be
evaluated in terms of its contribution
to the total organic chemical
contamination load, or against other
specific contaminants, so that some
differentiation of source contributions
to the overall plume can be obtained.
Two chemical analysis represented
in the manner originated by Stiff
1.5 1.0 0.5
0.5 1.0 1.5
I I I I I I I
^
CI
SO
Figure 23 Stiff Diagrams of Major Ions in Two Water Samples
The concentration of each ion is plotted in the manner shown in (a);
the uniqueness of another sample is shown by (b).
19
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Perspectives for Site Characterizations
Concepts pertinent to investigating and predicting the transport and fate of contaminants in the subsurface
are evolving. An appreciation for this fact is important because there seems to be widespread overconfidence by
decision makers regarding detection and remediation of contamination in the subsurface. From a practitioner's
perspective, it appears that there is too little emphasis in most subsurface contamination assessments on
obtaining detailed information about preferential pathways of contaminant transport and about the natural
processes that affect the transport behavior and ultimate fate of contaminants. Additional effort devoted to
sitc-speciflc characterizations of natural process parameters, rather than relying almost exclusively on chemical
analyses of ground-water samples, may significantly improve the quality and cost-effectiveness of remedial
actions at hazardous waste sites.
1. Characterization Approaches
To underscore the latter point, it is useful toexamine the principal activities, benefits, and shortcomings of
increasingly sophisticated levels of site characterization approaches: conventional (Table 2), state-of-the-art
(Table 3), and state-of-the-science (Table 4). The conventional approach to site characterizations is typified by
the description given in Table 2:
it!
ACTIONS TYPICALLY TAKEN
~ Install a few dozen shallow monitoring wells
* Sample ground-water numerous tunes for 129+ priority pullutants
• Define geology primarily by driller's log* and drill cutting*
• Evaluate load hydrology with water level contour map* of shallow wells
* Possibly obtain soil andcore samples for chemical analyses
BENEFITS
• Rapid screening of the site problems
* Costs of investigation are moderate to low
If Field and labor atoiy technique* Usedarestandard
* Data analysis/interpretation u straightforward
s* Tentative Identification of remedial alternative* is possible
SHORTCOMINGS t
• True extent of site problems may be misunderstood
* Selected remedial alternatives may not be appropriate
• Optimization of final remediation design may not be possible
• Clean-np costs remain unpredictable, tend to excessive levels
* Verification of compliance is uncertain and difficult
Table 2. Conventional Approach to Site Characterization
Note that each activity of the Conventional Approach can be accomplished.with semi-skilled labor and c
shelf technology. Together with moderate to low costs, this ready availability of tools and techniques is i
enough for perpetuation of the Conventional Approach — until one notes the shortcomings. It is not pa
thoroughly characterize the extent and probable behavior of a sii
Conventional Approach;
it is, by design, a compromise between
and the equal desire to keep expenses to an absolute minimum.
Key management uncertainties regarding the degree of health threat posed by a site, the selection of
appropriate remedial action technologies, and the duration and effectiveness erf the remediation* all should
decrease significantly with the implementation of more sophisticated site characterization approaches.
Certainly, such has been the outcome in the several site investigations known to the author.
20
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RECOMMENDED ACTIONS
• • Install depth-specific clusters of monitoring wells
i< * Initially sample for 129 + priority pollutants, be Selective Subsequently
; 4 * Define geoJogy by extensive conng/sediment samplings
* Evaluate local hjrclrology with weuclusters and ^eohydraullc tests
* Perform limited tests on sediment samples ([gram size, clay content, etc.)
C:. * Conduct surface geophysical surveys (resistivity, EM, ground-penetrating radar)
BENEFITS
* Conceptual understandings of site problems are more complete
* Prospects are improved for optimization of remedial actions
* Predictability of remediation effectiveness is increased
' / * Clean-up costs are lowered, estimates are more reliable
* Verification of compliance is more soundly based
SHORTCOMINGS
* Characterization costs are somewhat higher
* Detailed understandings of site problems are still difficult
* Full optimization of remediation is still not likely
* Field tests may create secondary problems (disposal of pumped waters)
Table 3. State-of-the-Art Approach to Site Characterization
By inspection of Tables 2,3, and 4, one may infer that it is likely to cost substantially more to implement state-of-
the-art and state-of-the-sdence approaches in site characterizations, but one should also infer that the increased
value of the information obtained is likely to generate offsetting cost savings by way of dramatic improvements in
the technical effectiveness and efficiency of the site clean-up.
IDEALIZED APPROACH
* Assume the state-of-the-art approach as a parting point
* Conduct tracer tests and borehole geophysical surveys (neutron & gamma)
* Determine the percent organic carbon and cation exchange capacity of solids
* Measure redox potential, pH, and dissolved oxygen levels of subsurface
* Evaluate sorption-desorption behavior by laboratory eohimo & batch studies
* Assess the potential for biotransformation of specific compounds
; BEBEFITS
- * Thorough conceptual understandings of she problems are obtained
* Full optimization of the remediation is possible
* Predictability of the effectiveness of remediation is maximized
4 Clean-up costs may be lowered significantly, estimates are reliable
* Verification of compliance is assured
SHORTCOMINGS
* Characterization costs may be significantly higher
',V * Few previous applications of advanced theories k methods have been completed
*' - * Field A laboratory techniques are specialized and not easily mastered
* Availibility of specialized equipment is low, non-commeraalized
Table 4. State-of-the-Science Approach to Site Characterization
21
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These economic trade-offs-arc illustrated conceptually in Figure 24. The illustration provided there is meant
to imply that modest increases in site characterization expenses (pregumablyfor more wphkttcatcd'data
increased use of more sophisticated techniques, since clean-up costs normally comprise the majority of site
expenditures.
HIGH
h
CO
O
o
>
p
<
uj
LOW
TOTAL COSTS
CLEAN-UP COSTS
INVESTIGATION COSTS
CONVENTIONAL STATE-OF-
APPROACH THE-ART
STATE-OF-
THE-SCIENCE
Figure 34 Relative Trade-Offs of Technical Level of Site Investigation Approaches w.
Cost
it I, po^e .0« U to
techniques are brought to bear on a proown"w» ^ ^tcmpt* at a remedial investigation turn up additional
The latter situation is when the RI was budgete^^ im^emented, and because
-------
Incorporation of some of the more common state-of-the-art site investigation techniques, such as pump
tests, installation of vertically-separated clusters of monitoring wells (shallow, intermediate, and deep) and river
stage monitors, and chemical analysis of sediment and soil samples would likely result in the kind of remediation
illustrated in Figure 27. Since a detailed understanding of the geology and hydrology would be obtained, optimal
selection of well locations, wellscreen positions and flowrates (the values in parentheses, in gallons per minute)
for the remediation wells could be determined. A special program to recover the add plume and neutralize it
would be instituted. A special program could also tie instituted for the pesticide plume. This approach would
probably lower treatment costs overall, despite the need for separate treatment trains for the different plumes,
because substantially lesser amounts of ground-water would be treated with expensive carbon filtration to
remove non-volative contaminants.
tributary
Figure 27 Moderate State-of-the-Art Clean-up of the Hypthetical Ground-Water Contamination Site
Ousters of vertically-separated monitoring wells and an aquifer test art used to tailor the remedy to the
hydrvgeoiogy of the site.
The extraction weliscreens positions become increasingly deeper as one gets closer to the river, because
monitoring well clusters have indicated that the plume is migrating beneath shallow accumulations of clays and
silts to the deeper, more permeable sediments. Approximately two-thirds of the extracted and treated ground
water is reinjected through injection welkcreens that have been positioned deep to avoid diminUtnng the
effectiveness of nearby extraction welts. As in the conventionally-based remedy, the remediation weufield would
be scheduled to operate for the amount of time needed to remove a1volume of water that is based on average
contaminant retardation values and the volume of ground water residing in the zone of contamination - except
that the detailed geologic and hydrobgic information acquired would result in an expectation of more rapid
cleansing of specific portions of the zone of contamination than elsewhere. The decision makers would have
based their approval of this remedy on the presumption that the remediation is optimized to the point of
providing the most effective clean-up, though the efficiency of the remediation may be less than optimal.
25
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If all state-of-the-art investigation tools were used at the site^ there would be an opportunity to evaluate the
desirability of using a subsurface barrier wall to enhance remediation efforts (Figure 28). The wall would not be
expected to entomb the plumes, but would serve the purpose of limiting pumping to contaminated fluids; rather
than having the extracted waters diluted with fresh waters available to the extraction wells, as was true of the two
previous approaches. The volume pumped would be lowered because the barrier wall would increase the
drawdown at each well by hydraulic interference effects, thereby maintaining the same effective hydrodynamic
control with lesser pumpage (note the lower values in parenthesis, at each well). Treatment costs would be
lowered as well, because the waters pumped would contain higher concentrations of contaminants; treatment
efficiencies normally fall with decreasing concentrations. Soil washing techniques would be used on the pesticide
contaminated area to minimize future source releases to ground water.
tributary
The efficiency of the remediation would therefore appear to be optimal, as well as the effectives hll, tW
is a perception based on the presumption that contaminants are readily released. Given • .
to pump-and-treat remedialions that were discussed in earlier sections of this rf~».mfnf bc«^wir r°?s
thai this advanced state-of-the-art site investigation precludes further improvement Just.?ubtfui
the chemical and biological pecularities is needed, as has been given to the seoloev and th« 10
of average retardation values from the literature infers that additional improvements in 1 usc
efficiency can be garnered by detailed evaluation of contaminant retardation at this site iS "! .
examination of the potential for biotransformation would be expected to garner additionaUffSeieM Md
26
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At the state-of-the-science level of site characterization, tracer tests could be undertaken which would provide
good information on the potential for diffusive restrictions in low permeability sediments and on anisotropic
biases in the flow regime. Sorption behavior of the VOC's could be evaluated in part by determinations of the
total organic carbon contents of the subsurface sediments. Similarly, the cation exchange capacities of
subsurface sediment samples could be determined to obtain estimates regarding release rates and mobilities of
toxic metals. The stabilities of various possible forms of elements and compounds could be evaluated with
measurements of pH, redox potential, and dissolved oxygen - something that may be particularly germane to the
acids plume and the phenols plume. Finally, if state-of-the-sdence findings regarding potential
biotransformations could be taken advantage of, it might be possible to effect in-situ degradation of the phenols
plume, and remove volatile residues too (Figure 29).
tributary
Figure 29 State-of-the-Science Clean-up of the Hypothetical Ground-Water Contamination Site
Bioreclamation and other emerging technologies could be tested and implemented with reasonable certainty
about the outcome.
The foregoing discussion should serve to signify the tremendous gains in effectiveness and efficiency of
remediation that should be expected bv better defining ground-water contamination problems and using that
information to develop site-specific solutions, rather than implementing generalized solutions that have come
into common practice out of a lack of recognition of the true economics involved. Moreover, it is only by a
thorough understanding of the problem, generated during the site characterization studies, that one is afforded
the opportunity to evaluate the performance of a pump-and-treat remediation. It is that such
evaluations be conducted, because pump-and-treat is not & proven technology. Rather, pump-and-treat
remediation is a method of fluid removal borrowed from water-supply technology, where an adequate supply of
ground water - not management of water quality variations - has Men the primary objective.
27
-------
Summary/Conclusions
ht. The variations in ground-
ation wellfields tremendously
for fo^er predictions and evaluations. Just as it is improbable that a
monitoring wells we rc°(|"c
-------
Optimizing Pumping
Strategies for
Contaminant Studies and
Remedial Actions
by Joseph F. Keely
Abstract
One of the more common techniques for controlling
the migration of contaminant plumes Is the use of
pumping wells to produce desired changes in local
flow rates and hydraulic gradients. When seeking to
optimize an array of pumping well locations and dis-
charge rates, it Is important to consider the effects
that non-Ideal aquifer conditions, well construction
and demographic constraints produce. Heterogeneous
and anisotropic aquifer conditions seriously compli-
cate si ting and discharge rate requirements for pump-
ing wells because of the distorted cones of depression
that result from withdrawing water in such settings.
Proper screen selection, gravel pack emplacement and
well development are crucial factors afTectlng the
operational characteristics and economics of pumping
wells; these factors are generally recognized, though
often undervalued. The impacts that well depth and
diameter, and screen length and position have on the
effectiveness of pumping efTorts are also often under-
valued. with detrimental consequences. Perhaps the
most difficult problems to overcome in designing
pumping schemes, however, are posed by demographic
constraints. Denial of property access, vandalism and
the unpredictability of nearby water supply and irri-
gation pumpage tend to wreak havoc with the best of
pumping strategies.
Introduction
Safe storage and disposal of hazardous wastes have
become major social issues because of the discovery
that many sites lack proper precautions for the pre-
vention of soil and water contamination. Ground water
contamination has received the major share of socie-
ty's attention to thes^ issues, primarily because the
route of human exposure by this pathway is direct. In
practical terms, this means that the level of cleanup of
the damage done by contamination incidents is often
dictated by social concerns (e.g. health risk). Plume
stabilization by Interception and control with perime-
ter wells, injection and recovery loops, and other
pumping schemes may be chosen as the "remedial
action" appropriate for apartlcularplume. The affected
plume may be held in place and treated, it may be held
and allowed to move on after alternate public supplies
have been located for downgradlent water systems, it
may be held in'place to allow biodegradatlon of
particular constituents, or it may be held until better
treatment procedures can be devised.
Factors Affecting Pumping Strategies
Hydrodynamic control and recovery strategies vary
considerably in their eindencles. Besides the obvious
need to choose the well locations and flow rates care-
fully, a number of other considerations demand atten-
tion (Figure 11. Non-ideal aquifer conditions are a
realiiyfor virtually all real-life situations; heterogeneity
Is the rule rather than the exception. Three-dimen-
sional anisotropy, as expresed by the vertical vs. hori-
zontal hydraulic conductivity ratio, is a near certainty
for most strata. Less visibly pronounced, yet almost as
prevalent is an expressed anisotropy in the horizontal
plane of many strata. These commonplace non-Ideal
aquifer conditions complicate our perception of where
a given plume can go (Fetter 1981) under both natural
flow conditions and remedial action pumping schemes.
The preferential flow paths that are created by buried
lake beds, glacial outwash gravels, stream beds, coastal
deposits and the like cannot be delineated without
expensive and time-consuming field tests. Likewise, it
Is nearly impossible to accurately predict the magni-
tudes of distortion in the cones of depression created
by wells pumping from heterogeneous, anisotropic
aquifers.
Variations in the properties of the fluid In an
aquifer, particularly the solution density, also can
significantly affect the behavior of contaminant
plumes (Jorgenson et aJ. 1982). Immiscible plumes
with lower density than that of the native ground
water will float at the surface of the saturated zone,
traveling along the same general gradient but traveling
-------
at a different rate than the underlying ground water.
Immiscible plumes with greater density than that of
the native ground water will sink through the ground
water, losing small but significant amounts of low
solubility constituents as they move. Miscibie plumes
of any density, by definition, mix Intimately with native
ground water. The duration of time required to achieve
a specific dilution by this mixing changes markedly,
however, and is generally inversely related to the den-
sity. For most situations, the greater the density, the
shorter the mixing period. The exception to this gen-
eral rule would be the case of a large volume of highly
dense, miscibie fluid penetrating a shallow aquifer
quickly enough to reach bedrock in a relatively undis-
turbed form. ___________
Considerations
Non-Ideal Aquifer Conditions;
• Heterogeneity
• Anisotroplsm
• Variable density
Well Construction Effects:
• Partial penetration
• Partial screening
• Incomplete development
Anthropogenic Influences:
• Property access
• Vandalism
• Unknown pumpage/injectlon
Other Factors:
• Physlochemlcal attenuation
• Biological transformations
• Operational failures
Figure 1. General considerations for optimizing pump-
ing strategies
These complexities work against us if we are Ignor-
ant of them. Working up an appropriate recovery sys-
tem for a contaminant plume can be compared to
designing an oil production system. What you get out
depends directly on what you put In—up to a point
Where that break-even point comes is hard to say,
given unknowns like the source strength and timing,
and immeasurables like the dollar value of additional
cancer victims. What Is abundantly dear, however. Is
that there is a substantial minimum for serious play.
One does not blithely draw up plans to pump and treat
a plume until considerable manpower and funds are
expended to obtain information on the natural flow
direction, gradlentand velocity. The question Is usually
one of how much to spend to reach some desired level
of detail: the level of detail Is set by social concerns.
This seems to be logical application of technology
for social need, but the logic may be shortsighted. If
social concerns (based on preliminary evaluation of a
contaminant Incident lane minimal, there Is no guaran-
tee that such social concerns are appropriate. Addi-
tional studies, which could delineate preferential flow
paths and quantify factors affecting contaminant
behavior, might well generate findings that would
Justify considerably greater or lesser social concern.
Quite often data from preliminary Investigations are
limited to samples from shallow on-site wells, which
may fall to signify the potential Impact of dense plumes
64 Summer 1984
or seasonally-occurring leachate pluines uiui haze
moved off-site. Additionally, the preliminary Investiga-
tion wells are not normally installed to a sufficient
depth for appreciation of the local stratlgraphlc and
llthologlc characteristics of the aquifer.
In addition to a better understanding of where
contaminants mightgo with the natural flow.asecond
powerful argument to avoid "penny-wise and pound-
foolish" investigations concerns the need to provide
the best Information possible for targeting well loca-
tions and pumping strengths in remedial actions. The
occurrence of specific heterogeneities can be used to
advantage by locating wells near low permeability clay
units to generate greater drawdown for a given pump-
ing rate. Likewise, knowledge of the direction of the
principal horizontal axis in anisotropic strata can help
to maximize the arrangement of the "troughs of
depression" for wells to be located In such settings:
knowledge of the magnitude of vertical anisotropy can
help determine the amount of water pumped from
strata containing contaminants vs. the amount of
"clean" water from the other strata open to the well.
This latter factor, vertical anisotropy. leads to
examination of some of the more controllable Items to
be considered in optimizing pumping strategies—well
construction effects. For example, the impact that par-
tial penetration of a fully screened pumping well can
have on the estimate of potential for contamination of
a water supply or on the effectiveness of a remedial
action scheme is tremendous (Saines 1981). The effect
is to cause exaggerated drawdowns near the well. The
magnitude of the effect Is Inversely dependent on the
degree of penetration of thewell into theaqulfer. being
greatest for slight penetration. Naturally, partial screen-
ing of a fully penetrating well results in the same
effect—greater drawdown for a given pumping rate as
compared with a fully screened, fully penetrating well.
Agala knowledge of these factors can be used to
enhance a pumping scheme that is. for example, de-
signed to maintain hydrodynamlc control of a plume at
the lowest possible level of pumpage. Lack of appre-
ciation of these well construction effects can result in
poor estimates of potential contaminant Impacts on
supply wells and In poorly designed remedial action
schemes. Another effect worthy of mention is that
generated by well development practices. If a well is
properly developed, the drawdown measurable inside
the well will agree with the level projected by close
observation weus. More often, however, a well is not
perfectly efficient because the well development pro-
cedures were not adequate to remove drilling fluid fines
and locally disturbed aquifer material res»iitlng from
the drilling process. These materials lower the permea-
bility of the gravel pack and formation immediately
adjacent to the well The greater the degree of well
Inefficiency caused by lack of proper development the
greater the amount of non-productive drawdown inside
the well: this means that the well may never be able to
pump at design capacity without risk of running dry.
and It means increased operating expense due to the
additional pump lift required What it may also portend,
for seriously inefficient wells, Is that certain strata
penetrated by the well may be effectively sealed by
drilling mud or by natural clays that were smeared over
the borehole face by the actions of the drilling operation.
Such "staled 0IT strata may carry the bulk of the
contaminants, resulting in poor recovery of the plume.
Some of the most significant though'Iess control-
lable. factors that should be considered when optlmiz-
-------
Ing pumping strategies concern direct anthropogenic
influences: denial of property access, vandalism and
unknown pumpage all tend to wreak havoc with the
best laid plans. Bedlent et al. (1984) describe efforts to
delineate a plume of contaminants migrating under a
residential area from an abandoned wood creosoting
plant In Conroe. Texas:
"Several wells exist in the general flow direc-
tion. but not directly downgradlent from the
waste pit locations. Access was not granted for
Installing monitoring wells... Approximately 50
percent of the chloride plume has been defined
since the monitoring well network is incomplete
at this time... Completion of the monitoring well
network is needed to capture the center of the
contaminant plume. This will require more wells
downgradlent on land that has not previously
been accessible for Investigation."
The granting of property access during Investiga-
tions of ground water contamination incidents in
populated areas is no trivial matter. One typically finds
i t necessary to contact not only homeowners and land-
lords for private property access, but also to negotiate
with company engineers, vice presidents and attorneys
for commercial property access. It is quite normal for
such negotiations to be involved and protracted as city
councils, educational boards, corporate headquarters
and other bureaucratlcentlties are asked toconcurln
signing access agreements containing provisions
deemed necessary to ensure against incurred liability
and potential damage.
The role played by unknown pumping and/or
injection wells operating near a remedial action pump-
ing system is subtle but far-reaching. Such unknown
stresses can significantly distort the flow field and
render remedial actions ineffective. Projections on
plume movement made during an investigation of a
ground water contamination incident would also be
In error ifunknown wells are causing distortion in the
flow field: both the direction and the speed of the
plume could be dramatically altered. The reason for
the subtlety of the effects of many such wells is that
their cyclic seasonal or on-demand pumping sched-
ules allow them to be detected only by continuous
recording of water level changes at numerous points
around the zone of interest Slnceaqulfer responses at
a given observation point are somewhat non-unique,
merely detecting extraneous sources of drawdown
does not automatically result in identification of the
sources.
There are a fewother important factors to consider
that also affect pumping strategies. The physiochemi-
cal properties of the contaminant itself can result In a
need to pump several pore volumes from each unit
volume of aquifer to be decontaminated. Sorption. Ion
exchange and speclatlon changes can result In re-
tarded movement of contaminants relative to the
average velocity of the water with which they are
initially associated. Biotransformation of contami-
nants may result In reaction products (daughter
productsl that are of greater or lesser toxicity, mobility
and persistence—in other words, uncertain contami-
nant behavior. Unlike the aquifer properties of storage
coefficient, saturated thickness and hydraulic conduc-
tivity, which can be readily determined, the current
state-of-the-sclence with regard to determining the
potentials for physiochemical attenuation and bio-
transformation is not up to the level of routinely
providing reliable answers on a site-specific basis.
Finally, an obvious but often overlooked considera-
tion involved in optimizing pumping strategies is the
need to develop adequate contingencies for operational
failures. This means some intentional overdeslgn for
reserve capacity, total redundancy of key wells and
electronic controls, backup power systems and so on.
It also means bonding or Insurance against unfore-
seen catastrophies so that as little downtime is
expended as possible. It may also mean that an escrow
account or trust fund must be established to provide
the necessary capital for replacement of burned-ou tor
inadequate pumps, deepening or abandonment of
existing wells, or drilling of additional wells.
Capture Zones vs. Zones of Pressure
Influences
Keely and Tsang (1983) Introduced the term "cap-
ture zone" to describe that portion of the aquifer
affected by pumping which actually yields water to the
well. They have shown that the capture zone is gener-
ally much smaller than the zone of pressure influence
because a balance is achieved, under steady-state
conditions, between the pull of water back toward the
well from its downgradlent side and the tendency of
the natural flow system to move on further downgra-
dlent. Figure 2 is a series of four idealized Illustrations
that present conceptualizations of how the size of the
capture zone changes, relative to the zone of pressure
influence/cone of depression, as the local gradient
Is Increased. In Figure 2A the well is pumping from a
stagnant aquifer. Indicated by the flat pre-pumpfng
surface, oyerlald on the theoretical cone of depression
that would occur during pumpage. For stagnant
aquifer conditions, the capture zone Is everywhere
Identical to-the zone of pressure influence and flow is
radial into the well As the successive diagrams indi-
cate. however, non-stagnant aquifer conditions lead to
smaller capture zones (Figures 2B to 2D).
The slopes of the pre-pumplng surfaces are overlaid
on the theoretical drawdown cones In each frame of
Figure 2 to emphasize the Interaction of the natural
flow system with the pumping stress to yield a capture
zone smaller than the zone of pressure Influence There
Is no Intention to show the net surface resulting from
pumpage by subtracting theoretical drawdown values
from pre-pumplng water elevations. These sketches
do have the cosmetic drawback of showing crossing
water level lines/curves, but the point is to Illustrate
the individual components of the net surface (cross-
sectional view) and how they interact to yield a capture
zone (three-dimensional view).
The flow lines generated by pumping a well from an
Idealized aquifer (homogeneous, Isotropic, constant
density, etc.) under different natural flow conditions
are shown In Figure 3. In Figure 3 a well pumping
1.000m3/dayfroma 10m thickaqulfer having a poros-
ity of 0.10 and a hydraulic conductivity of lOOm/day
has uniform radial flow under stagnant aquifer condi-
tions (e.g. natural flow velocity equal to zero). When a
mild hydraulic gradient (0.0001) Is Imposed on the
same system (Figure 3B), the resulting natural flow
velocity (0.1 m/day) is Insufficient to significantly affect
the flow lines, and uniform radial flow is nearly main-
tained. With a more moderate hydraulic gradient
(0.001). the resulting natural flow velocity (l.Om/day)
is sufficient to sweep away many of the flow lines and
the capture zone Is clearly evident (Figure 3C). Where
a steep gradient (0.01) Is present, the capture zone
diminishes to a small fraction of the zone of pressure
-------
vaoose zone
»R{-»UH^INOSUftFACI
VAOOSC ZONE
fA run AT« o IOHI
c»**9.s,ttra»Mt ta»tt0ta*tinria m..
SATURATEDZONC
tMBSS.sfcriOMAt
CAPTUHC lONI • COM! O*
C*MU«! tONI < CONC Of OCPfttltlON
mttr t>r»r»tra»jt e » , e r * n i t r I * T I LM
Figure 2A. Stagnant aquifer conditions
conc or ocfti iiion
l
-------
1 i i p 1 1 1 r
V*l: 0.0 m/4
-500.
-*00.
; i—i—t—u
¦ i ¦ i_
-0.
500.
0.
-500.
_1 L_ 1 L_
500. -500.
0.
500,
Figure 3A. Stagnant aquifer conditions
Figure 3B. Mild hydraulic gradient (0.0001)
-500. 0. 500. -500. 0. 500.
Flgura 3C Moderate hTdraullc gradient (0.001) Figure 3D. Steep hydraulic gradient (0.01)
Figure 3. flow llzw plots for a single well discharging l.OOOmVday from on aqulier with 10m saturated
thickness, lOOm/day hydraulic conductivity and 0.10 porosity
NOTE: Seal* is in meters and natural flow proceeds from lower left-hand corner to upper right-hand comer oi
each plot at the Telocity Indicated.
influence (Figure 30).
Comparing Pumping Strategies
A typical use of pumping schemes is to effect
hydrodynamlc control over a plume, either for tang-
term stabilization or for withdrawal and treatment.
Consider extending the example Illustrated by Fig-
ure 3. First, assume a line of five wells lying perpen-
dicular to the direction of natural flow (Figure 41. Each
of the Ave wells pumps 200m3/day. so that the total
pumpage of the five wells is the same as that of the
single well in Figure 3. Under stagnant aquifer condi-
tions to low natural flow velocities (Figures 4A and 4B)
there does not seem to be any difference in the effec-
tiveness of the pumpage from the five wells as com-
pared with the single well case (Figures 3A and 3B).
The situation changes markedly If moderate to high
natural flow velocities are present however, as depicted
in Figures 4C and 4D. As the natural flow velocity
increases, the capture zone of each of the Ave wells
diminishes to a point where adjacent capture zones
no longer overlap and natural flow lines run on
through the line of wells. By contrast the capture zone
of the single well pumping 1.000m3/day does not
develop holes, but does diminish In size to well below
the perceived size of the leaky collective capture zone
of the line of five wells.
In actuality, there Is no difference between the true
collective size of the capture zones generated by the
five wells and that generated by the single, high-flow
««•
-------
JUU .
0.
-500.
v»l! 0.0 m/4
. I
/ .*'•
_jj L -J-
juu
0.
-500.
Vali O.t mft
I..' I I.
V lil I
-500. 0. 500
Figure 4A Stagnant aqutfer conditions
-500. 0. 500
Figure 4& Mild hydraulic gradient (aOQOl)
500. 1 ' 1 1 T
v«n i.o «•/<
-t .¦ i ..'i
500.
o.
-500.
-500.
•'J.' ••.• ¦ i1'.¦
0.
500.
-500.
-500.
I®!®
0. 500.
Figure 4D. Steep hydraulic gradient (0.01)
Figure 4C Moderate hydraulic gradient (0.001) ^
^ ^awrft discharging 200m3/day tram cm aqullsr with 10m
» * wvwn •• <*r |#iranriv.« „
the capture zone upgradient of the well as: w^- w "r
lh*t V,.,). Using this relationship. It la apparent that
the maximum width (W_J of the capture zone of a
well Is directly and linearly related to Its flow rate (Qh
and is inversely related to the natural flow velocity
(V )
For the example discussed here regarding a single
well pumping l,OOOm3/day. the maximum width of
the capture zone is 1.000m when the natural flow
velocity is l.Om/day, and is 100m when the natural
flow velocity is lOm/day. Each of the Ave wells in the
second example discussed pumps at a flow rate equal
toone-flfth the flow rate of the well in the first example
(200m3/day). and each, therefore, has a capture zone
the maximum width of which is one* fifth that of the
single well (200m). Hence, by comparing Figure 3 with
Figure 4. it la seen that the way in which the total
pumpage is distributed does directly affect the distri-
bution of the capture zonds). but does not affect the
magnitude or total area of the capture zonels). Also to
be^een In Figures 3 ami 4 la that Increasing the
natural flow velocity estimate can lave a dramatic
impact on the effectiveness of the pumping strategy.
Given the order-of-magnitude uncertainty so often
associate^ with hydraulic conductivity estimates, it is
not surprising that many seemingly acceptable reme-
dial action schemes are doomed to fall miserably.
A more complicated example provides further Illus-
tration of these points. Assume that we have the same
48
Summer 19M
-------
500.
-500.
-500
1
—i—i—i—
I
" r * ¦!— i.
i
500.
i 1 " i • i
(
" 1i"
—i
-
•
*•1:0.1 m/d
-
*
*
m
-
*
»
-
0.
*
*
-
»*'
-
.
-
i. i . i
1
i i /¦_
i
-500.
1—UJ L.,l_
1 :
_i L i
.,..4,,;.-..
0.
500. -500.
500,
FlffUTB 5A Stagnant aquifer conditions
Figure 5B. Mild hydraulic gradient (0.0001)
500. f r~
lv«»i t.
h.-"
0.
I ••••''
K •••
f"y".
1
-500. ?
-500.
i 1 r
o mf*
-t r 1 1r
500.
.-H
"i*
*
.*
_j_..=ij. / I,-.' j i J
0. 500.
Figure SC. Moderate hydraulic gradient (0.001)
-500.
|, . r ; . n i |
vit! 1.0 .!•/«.
k-
• •
K:
-500.
I '.'.I'-'- I,,.', {'•
500.
Figure SD. Steep hydraulic gradient (0.01)
Figure 5. Flaw line plots for a did* of eight wells, each, discharging 125mJ/day from an aquifer with 10m
saturated thickness, lOOm/day hydraulic conducttrity and 0.10 porosity
NOTE; Scale Is In meters and natural flaw proceeds from lower left-hand comer to upper right-hand comer of
each plot at the Telocity Indicated.
aquifer conditions and total pumpage limitation
(1.000m3/day) aa the preceding examples. We will
distribute the pumpage uniformly by pumping each of
eight wells at 125m3/day. The eight wells are evenly
spaced around a circle of200m radius. We are tiyi ng to
hold a plume within the circle With stagnant aquifer
conditions to low natural flow velocities, the plume
appears to be stable; no flow lines pass through the
circle (Figures SA and SB). At moderate to high natural
flow velocities, however, thesltuation is quite different:
flow lines readily pass through the circle, indicating
that the plume stabilization attempt has failed (Fig-
ures SC and 5D).
A pump and treat scenario can be examined by
modifying the example shown in Figure 5 to change
the operation of the eight wells from pumping to
injecting and by adding a major pumping well in the
center of the circle The single pumping well will with-
draw 1.000m3/day from the plume. The withdrawn
water will be treated and re-Injected into the eight
injections wells at 125m3/day each. At zero to low flow
velocities, the injected water flows radially toward the
central pumping well, firming a dosed loop for recov-
ery and treatment of theplume (Figures 6A and 6B). At
moderate to high natural flow velocities, the recovery
loop is broken and an increasing amount of the
injected water and the plume are swept away by the
regional flow (Figures 6C and 6D). It must be empha-
sized that the cones of Impression or depression of the
wells overlap significantly for all of the multlwell exam-
ples discussed so far. Despite those overlaps, the net
surface resulting from the natural gradient and the
Summer 1984 69
-------
500. r».,.
u
, - r- i r
3UU .
I r I r '
V*l: 0. t m/d
*.
0. ~
0. -
~500 . ¦ ¦ i i L—i—
-500. 0.
Figure 6A Stagnant aquifer conditions
500 1 •''r -''
3UU- ».n i.o .«•/<••
r-;r—. \
-uJ
500.
-500.
-500
I.I I
0.
500
Figure 6B. Mild hydraulic gradient (0.0001)
^00. >^7To^ii7P"
i
vV.//
i
250. -
0. r
*y ./ *
*
-250.
-500.
_i_l- j.
-500.
-500. 0.
Figure <5C Moderate hydraulic gradient (0.001)
500.
-500. -250. 0.
Figure 6D. Steep hydraulic gradient (0.01)
I L. . ...J
250. 500.
dor into cm aquifer with 10m sataxot»d thickness, loom/dar nrdxaullc conaacttfltr and 0.10 porosity
NOTE: Scale Is in meters and natural flow proceeds from lower left-hand comer to upp«r right-hand comer ol
each plot at the velocity Indicated.
water level changes due to pumpage and/or Injection
la shaped such that the streamlines are truly as pre-
sented here. For further discussion of capture zones
and velocity distribution plots, see Keety and Tsang
(1983). The detailed theoretical development and
source code listings for the models that were used to
generate the stream line plots shown here are given in
Javandel et al. (1984).
A little More Detail
It was quite clear in each of the preceding examples
that the pumping strategy began to fall as the natural
flow velocities became appreciable. The tendency to
fall is generally becoming evident at a natural flow
velocity of l.Om/day and is beyond question at a
natural flow velocity of lOm/day. Figure 7 shows that
failure of each design is certain at 5.0m/day as well:
the point at which the flow lines break through must
be at much lower natural flow velocities.
In Figure 8 the natural flow velocity has been
reduced to 0.5 and 0.4m/day for the last two examples
only. Breakthrough of the streamlines (failure of the
pumping strategy) occurs somewhere between the 0.4
and 0.5m/day natural flow velocities. Similar compar-
isons for the first two examples are not presented
because flow line breakthrough does not apply to the
first example (a singe production well) and the flow
line did not Indicate breakthrough at l.Om/day for the
second example (a line of five wells).
The presence of an unknown well is being studied
in Figure 9. A major pumping well U.000m3/day) has
been arbitrarily located downgradlent of the same line
70
Summer 1984
-------
500,
i • r r-
jv«ls. i.Q-m/4
r\y'yyy'y
——)—-—r—
I .•
r ..
0. |r'
~r—
.a
t
.'"i
A
500
i
r
l..'
. ¦' ' '' f l '~ i ' I.-' j—
-500
-500. 0. 500
Figure 7A. Single well discharging l.OOOmVday
.-V'.y'y'P
-500.
-500.
: i, •' , i ¦; i_; i
t-'
' I." , i l' I.' L_l_
0. 500.
Figure 7B. Lin« ol Uv9 vmils, »ach discharging 200m5/dcrY
500.
0. -
-500.
-500
71—. i
V«4i (.0 m/4
500. £
.4
-r—--r:-— .j-"—t—,t iv - ~r\—
.' *
»
.* •* .'i
.¦ i
1
• i
• '-i
. i
, • i
.H
250.
0.
-250.
-500.
0.
500.
-500. -250
0.
250.
i
500.
Figure 7D. Single well discharging 1.000mi/dar, encircled
by eight wells Infecting I25mVday each.
Figure 7C. Circle ol eight wells, each discharging
laSmVdcpf
Figure 7. Comparison at pumping quays in an aquifer with 10m saturated thickness, lOOm/day hydraulic
eonducttvitr, 0.10 porosity-and 0.005 hydraulic gradient
NOTE: Scale is in meters and natural flow proceeds from lower left-hand comer to upper right-hand comer ol
each plot at the Telocity indicated.
of Ave wells discussed In the second example. Naturally,
under stagnant aquifer conditions, the unknown well
creates a hydraulic divide by distorting the flow field,
but it does not cause breakthrough of the (low line
from across the line of Ave wells (Figure 9A). With a
natural flow velocity of 0.5m/day, however, flow lines
do begin to break through the line of Ave pumping
wells (Figure 9B). Substantial failure of the pumping
scheme occurs at 1.0m/day natural flow velocity (Fig-
ure 9C). Contrast the onset of breakthrough due to
unknown pumpage (Figure 9BI with the same situa-
tion in the absence of the unknown pumpage (Fig-
ure 9D). The impact of the unknown well Is staggering,
not only because flow line breakthroughs are occur-
ring, but the collective stze of the capture zones of the
five pumping wells is being substantially reduced.
Another Illustration of the Impact of an unknown
well on the effectiveness of a pumping scheme is shown
in Figure 10. which is the same example as discussed
earlier (Figure 6) for a closed-loop aquifer rehabilita-
tion system. Under stagnant aquifer conditions, the
unknown well diverts flow away from two of the injec-
tion wells (Figure 1QA). At l.Om/day natural now
velocity, the unknown well diverts flow from Ave of the
eight injection wells (Figure 10B). It also allows flow to
break away from the well fleld entirely, as indicated by
the streamline leaving the uppermost Injection well
and heading downgradlent in Figure 10B. The re-
gional flow Tines were omitted from Figure 10 and
some of the diagrams in previous flgures because
inclusion of those flow lines would create confusion
due to the excessive number of plotted points.
Summer 1984
71
-------
-500. * ¦ i/ .J. / » • •' ' - • 1
-500. 0. 500.
Figure 8A. Circle of eight wells, each discharging
125mVday -with 0.0004 hydraulic gradient
500.
I
I
-500 . J - i / . I..', j ,'i. ;'i
-500. 0.
500.
Figure SB. Circle ot eight wells, each dlscharaina
125mVday, with 0.0005 hydraulic gradient
500.
f * 1 • | 1 r- • v • • r
V«ll O.S ' I
250.
* *
250.
V
0. -
0. -
•X*V"V'.. *
-250. -
H
V
-250. -
#•
-500.
-500.
. I
-250
0.
250.
500.
Figure 8G Single we 11 discharging 1,000m
by eight wells Injecting 125mVday each, with 0.0004
hydraulic gradient
-500.
-500.
,_a 1....
-250.
L.
0.
.. . I
250.
500.
Figure 8D. Single well discharging l.OOOmVday, encircled
by eight wells injecting 125mVday each, with 0.0005
hydraulic gradient
Flfluw 8. Detailed views of onset of flow line breakthroughs for two plume control strategies in an
aquifer with 10m saturated thickness, lOOm/day bTdraullc condactWtr and 0.10 porosity
NOTE: Scale is In meters and natural flow proceeds from lower left-hand comer to upper right-hand comer ot
•ach plot at the Telocity Indicated.
Conclusions
Heterogeneity, anisotropy, partial penetration and
so on distort drawdown patterns and associated velocity
distributions. If known, such influences can be used to
enhance recovery efficiencies for remedial actions. If
unknown, such Influences may cause recovery effi-
ciencies to be substantially lowered. Similarly, predic-
tions of plume migration In non-Ideal aquifers under
non-pumping/natural flow conditions will be strength-
ened by specific knowledge regarding the occurrences,
extent and magnitude of the non-ideal condltlon(s).
Such predictions may be seriously In error If non-ideal
conditions are not evaluated properly.
Denial of property access, loss by vandalism and
unpredictable operation of nearby wells are also major
sources of uncertainty in predicting contaminant
migration and In designing remedial actions. Though
commonly perceived to be less of an impact on opti-
mizing pumping strategies than non-ideal aquifer
conditions, these factors may Indeed be the most
uncontrollable and the most detrimental to opera-
tional success. Other factors that have major impacts
are the physiochemical attenuation and biotransfor-
mation potentials of the Individual contaminant: it is
not yet ecenomically feasible to conduct adequately
detailed studies of these potentials on a routine site-
specific basis. Finally, a factor often overlooked that
greatly Impacts optimization efforts is the risk of
72
Summer 1984
-------
500 1 ! 1 ! 1 ' 1
• v»t: 0.0 m/«
?.S0. -
0. -
.
¦SSO.
-500. i ! i I t I i .
-SOO. -?bO. 0. 250. 500.
Figure 9A. Stagnant aquiler conditions
5^0 ' V»li 1.0 m/4'
250. -
.'""V- /
-250. r-
-500.
-500. -250.
Figure 9C. Hydraulic gradient oi 0.001
500- v., 0.5 m/J
_ p
250. t- ¦
• *.
'//.v'.'*-."'- \
-250. r-
-500 . I.-"' / /l / /. / I
-500. -250. 0. 250. 500
Figure 9B. Hydraulic gradient of 0.0005
500 r r- •( r - > -i- -
',¦*•1(0.» m/i
0.
y'.ti-
-500.
— J. ..¦:l i . .-. I ..'..j.," t 'i •' i: .J
0. 250. 500. -500. 0. 500,
Figure 9D. Hydraulic gradient of 0.0005-wlthout the
unknown well
Fiauie 9. Influence of an unknown well discharging l,000m1/dcrr on flow line breakthroughs for a line of
five wells discharging 200m7day each from an aquifer with 10m saturated thickness, l(X)m/day hydraulic
conductivity and 0.10 porosity
NOTE; Scale Is in meters and naturalflowproceeds from lower left-hand comer to upper right-hand corner of
each plot at the velocity indicated.
mechanical and electrical operational failure: adequate
contingency plans must provide certain minimal levels
of excess/reserve capacity and redundancy of key sys-
tem components.
The capture zones of wells do not equal their asso-
ciated zones of pressure influence (cones of depres-
sion). except for stagnant aquifer conditions. Velocity
distribution plots must be constructed to define
potentials of contaminant migration. In particular,
plotting the streamlines for various scenarios involv-
ing pumping and/or injection wells subject to a spe-
cific natural flow velocity can greatly assist the ground
water professional In selection of an optimal pumping
strategy.
Acknowledgments
Thanks go to Rosemary Keely and Christine
Doughty for (computer) drafting the illustrations.
Thanks also go to Renae Daniels for typing this
manuscript
Disclaimer
Although this article was produced by an employee
of the United States Environmental Protection Agency.
It has not been subjected to Agency review and
therefore does not necessarily reflect the views of the
Agency, no official endorsement should be inferred.
Summer 1984
73
-------
250.
0.
-250.
Vftl: 0.0 m/d
\ /•*,
*•
-500.
-500. -250. 0.
Figure 1QA. Stagnant aquiier conditions
rv• I: 1.0 m/d
250.
*•
0. -
*•••
*.'•••
250.
500.
.L
*• *
it--'
_L
JL
250. 500.
-500. -250. 0. 250.
Flguxs 10B. Hydraulic gradient of 0.001
.L I
500.
t _—_ . _, „_vr,rtwn mil discharging l.OOOmVday on flowlln* breakthroughs tot a single
»^p. ,^mdmrmigltto«proc««liir°mlow..l.«-iigndcom.rlouIip..ilah<-hmdcom.iol
•ach plot at th» TSlodtj lndlcatad.
References
Bedient, P.B., A.C. Rodgers. T.C. Bouvette. M.B. Tomson
and T.H. Wang. 1984. Ground water quality at a
creosote waste site. Ground Water, v. 22. no. 3, pp.
318-329.
Fetter. C.W. 1981. Determination of the direction of
ground water flow. Ground Water Monitoring
Review, v. 1. no. 3. pp. 28-31.
Javandel. L C. Doughty and C.F.Tsang. 1984. Ground
water transport: handbook of mathematical model*.
American Geophysical Union. Water Resources
Monograph 10.
Jorgensen. D.G.. T. Gogd and D.C. Slgnor. 1982.
Determination of flow in aquifers containing vari-
able-density water. Ground Water Monitoring Re-
view. v. 2. no. 2, pp. 40-45.
Keely, J.F. and C.F. Tsang. 1983. Vdoclty plots and
capture zones of pumping centers for ground water
investigations. Ground Water, v. 21. no. 6. pp.
701-714.
Salnes. M. 1981. Errors in interpretation of ground
water level data. Ground Water Monitoring Review,
v. 1. no. 1. pp. 56-61.
Biographical Sketch
Joseph F. Keely (Robert S. Kerr Environmental
Research Laboratory, U.S. EPA. P.O. Box 1198,
Ada. OK 74820) received his B.S. In professional
chemistry and M.S. in hydrology from the Uni-
versity of Idaho (Moscow). He is employed as a
hydrologist at EPA's Robert S. Kerr Environ-
mental Research Laboratory, where his efforts
are directed toward geohydraulic and hydro-
geochemical investigations of ground water con-
tamination incidents, coordination of ground
water modeling research and instructional
assistance. He sits on the Policy Board of the
International Ground Water Modeling Center
and serves as expert witness to the U.S. Depart-
ment of Justice for Superfund cases.
74
Summer 1984
-------
APPENDIX F
SUPPLEMENTARY MATERIAL FOR IN-SITU
SOIL WASHING AND FLUSHING TECHNOLOGIES
Thomas C. Sale, CH2M Hill, Denver, Colorado
-------
EPA/600/2-fl7/U0
December 1987
FIKT.D e"*ijnTv« -1 uoaOd
Of t/st~ vR'Satm
by
Jar.es H. Nosh
Kason tt Han^er-Sil^s Karon Co., Inc.
P.O. Box 11?
Leonardo, flew Jersey C7T37
Contract !Io. 63-03-3203
Project Oftteer
Richard P. Traver P.£«
Releases Control Branch
Land Pollution Control Division
Edison, Nev Jersey 0883T
HAZARDOUS WASTE' ENGINEERING RESEARCH LABORATORY
OFFICE OF FtfSFAF.CK ACT DEVELOPMENT
U.S. E?lVIROXMEISTAL PROTECTION AGENCY
CINCINNATI, OHIO U5268
-------
ABSTRACT
The U.S. Environmental Protection Atfvticy R*I.».-i>»es Control Branch and
the U.S. Atr Force En^ln^'fl'M and Services Center eng**,..! in a Joint
project focused on In situ washing of a fire training pit at Valk Air
National Cnard (A.'.'C) Sam-, Canp Douglas, Wisconsin. The washing fluids
were soluefotix of cumm^rrfaJIy available Kurf.ict.mtsi in water. Or' partic-
ular lnti*r>'>4t was .1 bl»*nd of AJ»<*v-' 799 and Hyouic p£90. This bUnd had
previously proved successful in laboratory .Htudle* involving tho cleaning
of organic ct>nt;rai nam* from soli. A second objective was to treat contam-
inated groundwater underlytug thr test site.
The fir* training pit had served as a sit* for flreflghtlng training
a* early .is World War II up until-deactivation in IV79. The subsurface
soil was deterai iu«d to be 85-952 saad and 5-152 finest. The cone«ml nat ton
wns principally a medium weight oil (2,000-25,000 Bg/fcg) with some vola-
tile* (V0A analysis 5-10 mg/kg). The uncunf Inert a«i«ilf#r at 12 feet depth
Is reported co be continuous to 700 feet. The saae aquifer s«rv«s ax the
water supply for the Camp Douglas. No amranlnaclan has been detected In
the wells supplying Che base nor private wells adjacent to the base.
However, organic carbon levels In the groundwater und«»r, and adjacent to,
the pit were measure;! as high as 700 lag/liter.
Small areas of the pit (ten squares that were one or two feet on a
side) were Isolated and surfactant solutions applied at a rate of 77 l/a2
per day for seven days. Cleaning efficiencies were determined based on
before fnd after otl and grease measurements. Full seal# air stripping and
pilot flushing operations reduced the total organic carbon by as much as
502. Volatile* In Che groundwater were reduced by 99Z.
lv
-------
IN SITU FLUSHING & SOILS WASHING
TECHNOLOGIES FOR SUPERFUND SITES
Presented at:
RCRA/Superfurtd Engineering
Technology Transfer Symposium
By:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
June 26-27, 1985
£
2J
O
\
w
c4
pROt^°
\
UJ
CD
r
£
-------
CH£MICAL CQUNTSRMEASURES PROGRAM
"SUPERFUND" RECOGNIZES THE NEED TO OEVELOP COUNTERMEASURES (MECHANICAL
OEVICES, ANO OTHER PHYSICAL, CHEMICAL, AND BIOLOGICAL AGENTS) TO MITIGATE THE
EFFECTS OF HAZARDOUS SU8STANCES THAT ARE RELEASED INTO THE ENVIRONMENT AND ARE
NEEDED TO CLEAN UP INACTIVE HAZARDOUS WASTE OISPOSAL SITES. ONE KEY COUNTERMEASURE
IS THE USE OF CHEMICALS AND OTHER ADDITIVES THAT ARE INTENTIONALLY INTROOUCTED
INTO THE ENVIRONMENT FOR THE PURPOSE OF CONTROLLING THE HAZARDOUS SUBSTANCE.
THE INDISCRIMINATE USE OF SUCH AGENTS, HOWEVER, POSES A OISTINCT POSSIBILITY
| THAT THE RELEASE SITUATION COULD 8E. MADE WORSE 8Y THE APPLICATION OF AN ADDITIONAL
CHEMICAL OR OTHER ADOITIVE.
08JECTIVE
TO DEFINE TECHNICAL CRITERIA FOR THE USE OF CHEMICALS (E.G., SURFACTANTS;
NEUTRALIZATION, OXIDATION/REDUCTION, PRECIPITATION AGENTS, ETC.) AND OTHER
ADOITIVES (E.G., 8I0STIMULANTS ANO BACTERIAL CULTURES) AT RELEASE SITUATIONS SUCH
THAT THE COMBINATION OF RELEASED SU8STANCE PLUS THE CHEMICAL OR OTHER ADDITIVE,
INCLUOING ANY RESULTING REACTION OR CHANGE,) RESULTS IN THE LEAST OVERALL HARM
\
TO~HUMAN HEALTH ANO TO THE ENIVRONMENT! ~ "
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' 7K.
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W.'.—Ow'N
PSS6-1225
Treatment of Contaminated Soils with
Aqueous Surfactants
Science Applications International Corp.
McLean, VA
Prepared for
Environmental Protection Agency
Cincinnati, OE
Nov 85
TD
878
E47
1985 U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
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LIRS040 Hazardous Waste Library Information Retrieval System 09/25/1987
REFERENCE REVIEW Page 15
Title: Treatment of Contaminated Soils with Aqueous Surfacancs
Author I: Ellis, William D.
Author 2: Payne, J.R.
Author 3: McNabb, C.D.
Publisher: Hazardous Waste Engineering Research Laboratory, Office of.
Research and Development, USEPA
City: Cincinnati, OH
Government Report #s EPA/600/2-85/129 Report Order #: PB86-122561
Publication date: 0/1985 Pages: 84
Library of Congress #: TD878 .E47 1985 ID #: 14353620
Location/Employee #: CVQ
Keywords: 215DO Solid/Soil/Sediment
216AQ Hydrocarbons
216 £0 PC3's
33200 Solids Treatment
33800 In-Situ Treatment
Abstract
14353620
The overall objective of this project was to develop a
technical base for decisions on the use of chemical
cauntermeasures at releases of hazardous substances. Work
included a literature search to determine the nature and
quantities of contaminants at Superfund sites and the
applicability of existing technology^to m situ treatment of
contaminated soils. Laboratory studies were conducted to
develop an improved in situ treatment "J
^signed to determine whether " th*
efficiency of water washing could be obtained by
aqueous surfactants to recharge water used in a continuous
r*cycle.
use of aqueous nonionic surfactants for J®**
fPiked with PCBs, petroleum hydrocarbons, and chlorophenol
?«» developed through shaker table and soil column tasvs.
r'ntaminant removal from the soil was 9 P
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