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TRANSPORTABLE DEBRIS WASHING SYSTEM:
FIELD DEMONSTRATION RESULTS AND STATUS
OF FULL-SCALE DESIGN
Michael L Taylor, Majid A. Dosani, John A. Wentz, and Avinash N. Patkar
IT Corporation
Cincinnati, Ohio
Naomi P. Barkley
U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory
Cincinnati, Ohio
Charles Eger
U.S. Environmental Protection Agency, Region IV, Office of Emergency Response
Atlanta, Georgia
Presented at the
Third Forum on Innovative Hazardous Waste Treatment Technologies:
Domestic and International.
Dallas, Texas,
June 11-13,1991.
HEADQUARTERS LIBRARY
ENVfflONMENTAl PROTECTION AGENCT
WASHINGTON, O.C.2M60
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INTRODUCTION
EPA recently published (Federal Register, May 30,1991) an Advanced Notice
of Rule Making (ANPR) in which Potential Best Demonstrated Available Technology
for Contaminated Debris was addressed. In this publication, EPA sets forth suggested
regulatory definitions for debris and contaminated debris, indicates the applicability of
existing Land Disposal Restriction Treatment Standards as well as Superfund 6A and
6B Guidelines and describes in general the available technologies for treating
contaminated debris.
The suggested definitions for debris and contaminated debris are quoted
below.
Debris means solid material that: (1) has been originally manufactured or
processed, except for solids that are listed wastes or can be identified as being
residues from treatment of wastes and/or wastewaters, or air pollution control
devices; or (2) is plant and animal matter; or (3) is natural geologic material
exceeding a 9.5 mm sieve size including gravel, cobbles, and boulders (sizes
as classified by the U.S. Soil Conservation Service), or is a mixture of such
materials with soil or solid waste materials, such as liquids or sludges, and is
inseparable by simple mechanical removal processes.
Contaminated Debris means debris which contains RCRA hazardous waste(s)
listed in 40 CFR Part 261, Subpart D, or debris which otherwise exhibits one or
more characteristics of a hazardous waste (as a result of contamination) as
defined in 40 CFR Part 261, Subpart C.
In the ANPR it is stated that "promulgating land disposal restrictions (LDRs)
including treatment standards for solvents and dioxins, California list wastes and the
First Third, Second Third, and Third Third wastes, the Agency regulated debris
contaminated with these restricted wastes. The land disposal restrictions in 40 CFR
268 thus generally apply to contaminated debris, including such debris generated
from corrective actions and closures at RCRA-regulated land disposal sites, remedial
and removal actions at Comprehensive Environmental Response Compensation and
Liability Act of 1980 (CERCLA) (Superfund) sites; and private party cleanups."
In conjunction with the promulgation of LDR's, the EPA Risk Reduction
Engineering Laboratory funded a project under the SITE program to develop
technology which could be applied pn-site for the decontamination of debris. The
results of initial field testing of the pilot scale Debris Washing System (DWS) .
[Performed at the Ned Gray Site (RGB/transformers}] were presented at this
conference in May 1990.1
In this paper we describe results of a second field demonstration in which the
utility of the pilot scale DWS was demonstrated for decontaminating debris found at a
pesticide-contaminated site in Northern Georgia.
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DEMONSTRATION OF DWS AT SHAVER'S FARM DRUM DISPOSAL SITE
A demonstration of the DWS was conducted in August 1990 at the Shaver's
Farm drum-disposal site in Chickamauga, Georgia. Fifty-five gallon drums containing
varying amounts of a herbicide, Dicamba (2-methoxy-3,6-dichlorobenzoic acid), and
benzonitrile, a precursor in the manufacture of Dicamba, were buried on this 5-acre
site. An estimated 12,000 drums containing solid and liquid chemical residues from
the manufacture of Dicamba were buried there during August 1973 to January 1974.
EPA Region IV had excavated more than 4000 drums from one location on the site
when this demonstration occurred in August 1990. Figure 1 presents an aerial
photograph of the site.
The pilot-scale DWS and the steel-framed temporary enclosure were
transported to this site on a 48-foot semi-trailer and assembled on a 24 ft x 24 ft
concrete pad. Both the temporary enclosure and the DWS had previously been
erected and used at a PCB-contaminated site in Kentucky. Figure 2 shows the
temporary enclosure and the assembled DWS at the Shaver's Farm site. Ambient
temperature at the site during the demonstration ranged from 75 to 105 degrees
Fahrenheit.
Prior to the initiation of the cleaning process, the EPA removed the 55-gallon,
pesticide-contaminated drums from the burial site. The contaminated drums were cut
into four sections and the contaminated surfaces were sampled using a surface wipe
technique.2 Pretreatment surface-wipe samples were obtained from each section.
The drum pieces were placed into the spray tank of the DWS, which was
equipped with multiple water jets that blast loosely adhered contaminants and dirt from
the debris. After the spray cycle, the drum pieces were removed and transferred to the
wash tank, where the debris was immersed in a high-turbulence washing solution.
Each batch of debris was cleaned for a period of 1 hour in the spray tank and 1 hour in
the wash tank. During both the spray and wash cycles, a portion of the cleaning
solution was cycled through a closed-loop system in which the contaminated cleaning
solution was passed through an oil/water separator, and the aqueous solution was
then recycled into the DWS. After the wash cycle, the debris was returned to the spray
tank, where it was rinsed with fresh water. Figure 3 presents a schematic of the pilot-
scale DWS.
Upon completion of the debris cleaning process, posttreatment wipe samples
were obtained from each of the drum pieces to assess the residual levels of
benzonitrile and Dicamba. In the case of the metallic debris sampled in this study, the
posttreatment wipe sample was obtained from a location adjacent to the location of the
pretreatment sample. This was necessary because wiping the surface removes the
contamination, and if one were to wipe the same surface after cleaning, the results
obtained would be biased low.
Ail field demonstration activities performed under the SITE program were
governed by an EPA-approved, site-specific Health and Safety Plan.3 Hydrogen
cyanide was of particular concern at this site. In one instance during excavation,
inadvertent mixing of drum contents resulted in a release of hydrogen cyanide.
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Figure 2. The temporary enclosure and assembled pilot-scale
DWS at Shaver's Farm site.
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However, no airborne hydrogen cyanide was detected during operation of the DWS
(Draeger Tubes were used to assess airborne cyanide concentrations). Personnel
donned Level C protective gear while working near the contaminated drums.
As stated above, surface wipes were obtained using the same method as
described for assessing PCB contamination. The Dicamba and benzonitrile in the
surface wipes were quantitated using SW 846 analytical methods. Dicamba was
extracted from the gauze wipes using Method 3540 and quantitated using Method
8150. Benzonitrile was extracted using Method 3540 and concentrations in the
extracts were measured using SW 846 Method 8270.
RESULTS
The results obtained during this demonstration are summarized in Tables 1
and 2. The data provide an indication of the effectiveness of the DWS technology for
removing a pesticides and a related contaminant (benzonitrile) from the internal
surfaces of excavated drums. Pretreatment concentrations of benzonitrile in surface-
wipe samples ranged from 8 to 47,000 ug/100 cm2 and averaged 4556 ug/100 cm2.
Posttreatment levels of benzonitrile ranged from below detection limit to 117 ug/100
cm2 and averaged 10 jig/100 cm2. Pretreatment Dicamba values ranged from below
detection limit to 180 ug/100 cm2 and averaged 23 ug/100 cm2, whereas posttreat-
ment concentrations ranged from below detection limit to 5.2 ug/100 cm2 and
averaged 1 u.g/100 cm2.
Upon completion of the treatment, the spent surfactant solution and rinse water
were treated in the water treatment system, where they were passed through a series
of paniculate filters, and then through activated-carbon drums. The treated water was
temporarily stored in a 1000-gallon polyethylene tank pending analysis. The before-
and after-treatment water samples were collected and analyzed for benzonitrile and
Dicamba. The concentration of benzonitrile in the pretreatment water samples was
250 and 400 ug/L (analyzed in duplicate), and the posttreatment concentration was
below the detection limit of 5 jig/L The concentration of Dicamba in the pretreatment
samples was 6800 and 6500 ug/L (analyzed in duplicate), and the posttreatment
concentration was estimated to be 630 jig/L (value estimated due to matrix
interferences).
Because the concentration of Dicamba in the posttreated water sample was
630 u/L, the treated water stored in the polyethylene holding tank was pumped into an
onsite water-treatment system for further treatment before its discharge into a nearby
creek. Although the concentration of Dicamba in posttreatment water was an
estimated value, it was decided to send the water to the onsite water-treatment system
prior to discharge as a precautionary measure.
The test equipment was decontaminated with a high-pressure wash. The wash
water generated during this decontamination was collected and pumped into the
onsite water-treatment system. The system and the enclosure were disassembled and
transported back to Cincinnati in a semitrailer.
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Batch
Number
1
2
3
4
5
6
7
8
9
10
Sample
Number
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
2
Benzonitrile
Pretreatment
180a (50f>
130a(50)
125
90
43
28
4400
2700
47000
22000
10a(5)
83(5)
200
320
1400
3000
3500
22a (5)
1400
Pos treatment
NDC
NO
117
7.8a (5)
ND
ND
ND
ND
10a(5)
7.9a (5)
ND
ND
ND
10a(5)
28
ND
7a(5)
ND
ND
a Estimated result less than 5 times detection limit.
b Numbers in parentheses indicate the minimum detectable concentration of the analyte.
c None detected in excess of the minimum detectable concentration of 5 u,g/100crr?
unless otherwise specified.
Table 1. Results obtained in analyzing surface wipe samples
for Benzonitrile (fig/100 cm2).
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Batch
Number
4
5
6
7
8
9
10
Sample
Number
1
2
1
2
1
2
1
2
1
2
1
2
1
2
Dicamba
Pretreatment
1.9
3.4
NCF
ND
ND (2.7)
ND (2.7)
7.3a (2.7)
15
55
13
1.7
ND (2.7)
41
180
Pos treatment
0.63a
(0.27)b
ND
ND
2.6
ND
ND (2.7)
1.8
2.3
5.7a (2.7)
0.62a (0.27)
0.63a (0.27)
ND
0.30a (0.27)
0.34a (0.27)
a Estimated result less than 5 times detection limit.
b Numbers in parentheses indicate the minimum detectable concentration of the analyte.
c None detected in excess of the minimum detectable concentration of Dicamba at 0.27
unless otherwise specified.
Table 2. Results obtained in analyzing surface wipe samples
for Dicamba (u.g/100 cm2).
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FULL-SCALE DEBRIS WASHING SYSTEM: CONCEPTUAL DESIGN
This section describes the conceptual design of a full-scale version of the DWS,
which is based upon results obtained during bench- and pilot-scale work. The lessons
learned from these latter development stages are incorporated into the full-scale
design, and the elements that worked well have been retained. Figure 4 presents a
schematic block diagram of the full-scale DWS.
The debris will be loaded in a cylindrical basket, lifted by a crane, and lowered
into the wash/spray/rinse tank, in which the basket will rotate. The debris will then be
washed and sprayed with hot surfactant solution and finally rinsed with clean water. A
small bleed stream will be sent to the water treatment system to recondition the
surfactant solution while the process is in progress.
The full-scale system will be about 3 1/2 times (1000-gallon) the capacity of the
pilot-scale DWS and will be permanently mounted on two 48-ft flat-bed trailers. The
system will be semiautomatic and will be capable of cleaning 3 to 5 tons of debris per
8-hour day.
CONCLUSIONS
Field-test results reported in this paper and previously obtained using the pilot-
scale transportable DWS showed the unit to be highly reliable and rugged. Extreme
high ambient temperatures had little effect on the operation of the equipment. The
system was successfully previously used to remove PCBs from transformer casing
surfaces and in this present demonstration was shown to be efficacious for removing
certain pesticide and herbicide residues from drum surfaces. Although the system has
not been proven effective for removal of all types of organic contaminants from the
surfaces of debris, results obtained to date are considered promising.
The cleaning solution was recovered, reconditioned, and reused during the
actual debris-cleaning process, which minimized the quantity of process water
required for the decontamination procedure. The water treatment system was effective
in reducing contaminant concentrations to below the detection limit.
The planned progression of this U.S. EPA-developed technology is continuing
with design, development, and demonstration of a full-scale, transportable version of
the DWS unit.
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REFERENCES
1) Taylor, M. L, Dosani, MA, Wentz, J.A., et al. "Results of Field Demonstration of
Debris Washing System," Presented at the 2nd Forum on Innovative Hazardous
Waste Treatment Technologies: Domestic and International, Philadelphia, PA,
May 1990.
2) Field Manual for Grid Sampling of PCS Spill Sites to Verify Cleanup, U. S.
Environmental Protection Agency, EPA 560/5-86/017, May 1986.
3} Standard Operating Safety Guides, Office of Emergency and Remedial
Response, Hazardous Response Support Division, Edison, NJ, November
1984.
ACKNOWLEDGMENTS
This research was funded in its entirety by the United States Environmental
Protection Agency's Risk Reduction Engineering Laboratory under Contract No.
68-03-3413. Naomi Barkley is the Technical Project Monitor.
DISCLAIMER NOTICE
This paper was prepared as an account of work sponsored by an agency of the
United States Government. Neither the United States nor any of its employees, nor
any of the contractors, subcontractors, or their employees make any warranty,
expressed or implied, or assume any legal liability or responsibility for any third party's
use or the results of such work or of any information, apparatus, product, or process
disclosed in this paper or represent that its use by such third party would not infringe
on privately owned rights. The views and conclusions contained in this document are
those of the author and should not be interpreted as necessarily the official policies or
recommendations of the U. S. Environmental Protection Agency or of the U. S.
Government.
This paper has not yet undergone peer review by EPA Risk Reduction
Engineering Laboratory. Subsequent to peer review the contents may be revised.
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