United States
Environmental Protection
Agency
EPA/540/SR-92/015
October 19i2
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Technology Demonstration
Summary
SITE Program
Demonstration of a Trial
Excavation at the
McColI Superfund Site
Region IX of the U.S. Environmental
Protection Agency (EPA), In coopera-
tion with EPA's Air and Energy Engi-
neering Research Laboratory (AEERL)
and EPA's Superfund Innovative Tech-
nology Evaluation (SITE) Program, and
with assistance from the California De-
partment of Health Services (DHS),
conducted a trial waste excavation
project at the McColI Superfund she In
Fu Norton, CA.
In the early to mid-i940s, the McColI
site was used for disposal of acidic
refinery sludge, and In 1982, It was
placed on the National Priorities List
(NPL). The McColI waste Is known to
release volatile organic compounds
(VOCs) and sulfur dioxide (SO,) when-
ever disturbed. Since 1984, the entire
site has bean covered with soil In an
attempt to minimize atmospheric emis-
sions of VOCs and SO.
In February 1989, EPA and DHS Is-
sued a proposed plan for the McColI
project selecting thermal destruction,
either on or offslte, as the preferred
remedy. An Important component of
this remedy Is the excavation and
waste-handling activities that must oc-
cur before thermal destruction. The
overall goal of the trial excavation was
to obtain Information pertaining to these
activities that would support the selec-
tion of thermal destruction as the pre-
ferred remedy and that would aid In the
design of a thermal destruction remedy.
EPA determined that the trial exca-
vation was necessary to ascertain If
the McColI waste could be excavated
with conventional equipment without
releasing significant amounts of VOCs
and SO to the surrounding community.
The trial excavation was also necessary
to define the treatment needed, If any,
to Improve the handling characteristics
of the waste as a precursor to thermal
destruction. The trial excavation was a
research project designed to gather In-
formation for use in the design of the
final remediation for Superfund sites
and specifically for the McColI Super-
fund site In Fulierton, CA.
This Summary was developed by
EPA's Air and Energy Engineering Re-
search Laboratory, Research Triangle
Park, NC, and Risk Reduction Engineer-
Ing Laboratory, Cincinnati, OH, to an-
nounce key findings of the SITE pro-
gram demonstration that Is fully docu-
mented In a separate volume of the
same title (see ordering Information at
back).
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Objectives
The trial excavation was conducted on
a portion of the Los Coyotes sump L-4.
The objectives of the trial excavation are
presented below. Based on the goal and
objectives of the project, EPA believes
that the trial excavation was successful
and that significant information useful in
the design phase of the McColl remediation
process was obtained,
Objective 1: To excavate approximately
100 yd9 of waste to assess waste-handling
characteristics and to determine if any
treatment is required to improve handling
characteristics as a precursor to thermal
destruction.
More than 130 solid yd3 of waste mate-
rial (mud, tar, and char) was excavated
under the enclosure using conventional
excavation methods.
During the trial excavation, it was de-
termined that the mud and char material
did not need further treatment. For the
mud, it was apparent that the waste could
be easily sized to the nominal 2-in.-diam-
eter thermal destruction requirement. For
the char, it was determined that more
than 50% of the excavated char was under
2 in. in diameter and that the remaining
material could easily be sized using con-
ventional methods [i.e., pug mill, shredder].
The tar material, however, required ad-
ditional treatment to allow for future pro*
cessing into a thermal destruction unit.
Mixing the tar with cement or fly ash and
water in a pug mill resulted in pellets that
were less than 2 in. in diameter.
Objective 2; To determine the atmo-
sphere emissions resulting from the ex-
cavation activities.
This objective was only partially
achieved during the trial excavation. Data
for SO2 and total hydrocarbons (THC) are
reported; however, no data for organic
species or reduced sulfur species are re-
ported.
High quality data were obtained for SO2
and THC emissions exiting the enclosure
exhaust treatment system. Five-minute
averages for SO2 emissbns were main-
tained at less than 1 ppm throughout the
project. The highest 5-min average for
THC emissions was §8.1 ppm.
Although samples for organic and re-
duced sulfur compounds were collected
from the stack and analyzed, an EPA au-
dit deemed them invalid. Benzene (a
known carcinogen), toluene, ethyl ben-
zene, and xylenes are the major constitu-
ents of the THC concentrations reported,
but no quantifiable concentrations for these
compounds can be reported for the rea-
son listed above.
Objective 3: To assess the degree of
SOj, and THC emission control achieved
through the use of an enclosure and an
enclosure exhaust treatment system.
The excavation area was enclosed, and
ventilation air was exhausted through an
enclosure exhaust treatment system con-
sisting of a sodium-hydroxide wet scrubber
and an activated carbon unit.
The daily average removal efficiency
for SO, ranged from 71.8% to 99.9% with
over 90% removal achieved on the majority
of days.
The daily average removal efficiency
for THC ranged from 15.8% to iO.7% with
over 50% removal achieved on the majority
of days.
Objective 4: To determine the emission
levels for SO. and VOCs at the fence-line
of the McCoO site as an Indicator of the
effect on the beat community.
This objective was partially achieved for
the reasons outlined in Objective 2. Reli-
able data for SO2 and THC emissions were
collected at four perimeter monitoring sta-
tions; no levels were detected that would
adversely affect the surrounding commu-
nity.
An EPA audit determined that the
samples for organic and reduced sulfur
compounds collected at the fence-line and
In the community and then analyzed were
invalid. For this reason, no quantifiable
concentrations of benzene (a known car-
cinogen), toluene, ethyl benzene, and xy-
lenes, the major constituents of the THC
concentrations reported, can be reported.
Objective 5: To assess the effectiveness
of vapor-suppressing foam.
This objective was partially achieved.
Reduction efficiency rates have been cal-
culated for dynamic conditions, but the
rates could not be calculated for static
conditions because an EPA audit deemed
the analytical data invalid.
In dynamic conditions, it has been esti-
mated that the vapor-suppression foam
can be up to 80% effective for SO, control
and 60% effective for THC control.
Static flux chamber measurements were
conducted on the mud, tar, and char within
the enclosure. The gas streams from these
tests were analyzed for organic com-
pounds and reduced-sulfur compounds;
an EPA audit, however, determined the
data to be invalid.
Objective 6: To assess potential prob-
lems that might occur during excavation.
Assessments were made regarding
problems that occurred because of higher-
than-expected emissions of SO2 and THC
from the tar and char; high paniculate
diesel emissions; heat gain; work in Level
B and Level A protective gear; excess
water in a confined space; and seepage
of tar material.
Excavation and Waste
Processing
Overburden was removed and the un-
derlying waste was excavated with a
trackhoe equipped with an extended boom
and a 1-yd3 bucket. The waste, which was
found to be fairly well segregated into
layers, was placed in roll-off bins or piles
for subsequent use. After routine removal
of the overburden, a 3-ft-thick mud layer
was excavated. A 4-ft-thfck tar layer was
excavated next. After the tar was removed,
a trench shield was placed in the exca-
vated area to reduce additional tar seeping
Into the opening. After the tar layer, a
hard, coal-like, char layer was encoun-
tered. This material was broken up and
excavated with the trackhoe.
During the tar excavation, SOZ and THC
levels within the enclosure increased dra-
matically and reached 5-min average val-
ues of 1000 and 492 ppm, respectively.
The enclosure exhaust treatment system
removed up to 99.9% of the SO# and 60%
of the THC during this excavation period.
The use of the enclosure and enclosure
exhaust treatment system prevented any
significant amounts of these pollutants from
reaching the site perimeter, as evidenced
by the low concentrations measured there.
The higher-than-expected concentrations
within the encbsure required personal
protection equipment to be upgraded to
Level A (completely encapsulated suit with
supplied air).
During the char excavation, high con-
centrations of SO2 and THC were also
reached—5-min average values of 755
and 355 ppm, respectively. The enclosure
exhaust treatment system operated effi-
ciently during the entire study with up to
99% removal of the SO2 and up to 90.7%
removal of the THC,
The failure of vapor-suppressing foams
to form an impermeable membrane over
the exposed wastes caused higher-than-
expected levels of SO and THC within the
enclosure. The foams reaction with the
extremely acidic waste severely affected
the foam's ability to suppress emissions.
This ability was improved somewhat,
however, when the concentration of foam
reagents in water was increased. Though
difficult to estimate, the overall reduction
with foam was estimated at up to 80% for
SO2 and 80% of the THC; this is based on
concentrations measured at the enclosure
exhaust treatment system inlet during ex-
cavation activities with and without foam.
In all, 137 yd' of waste and 101 yd3 of
overburden were excavated. Maximum and
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average trial excavation rates are summa-
rized in Table 1.
Table 1. Maximum and Averse Trial
Excavation Rates (yd3/hr)
Component
Maximum Average
Overburden
Mud
Tar
Char
51
66
58
9
7.6
4.1
4.3
2.6
The average excavation rates achieved
during this trial excavation will be increased
considerably during full-scale excavation
as fewer observations and measurements
will be needed. Anticipated average exca-
vation rates that could be achieved during
full-scale excavation are estimated at 49,
32, and 25 yda/hrfor overburden and mud,
tar, and char, respectively.
The tar waste was further processed to
reduce its size and to form a solid and
easier-to-handle pellet. Tar was mixed with
cement, fly ash, and water in a pug mill,
and 10 test runs were made within the
enclosure at various ratios of tar, cement,
fly ash, and water. A ratio of 1 part tar to
between 2.3 and 7 parts cement and fly
ash and from 0.26 to 1 part water formed
a solid, easy-to-handle pellet. Approxi-
mately 3 tons of tar per hour was pro-
cessed during the trial excavation, and it
is estimated that this rate could be in-
creased by up to a factor of 2 with a more
continuous operation. Indications were
evident that tar processing with alkaline
materials such as cement and fly ash re-
duced the amount of SO2 released by the
tar, The mud and char waste fractions did
not require further processing but could
have been fed through the pug mill, if
necessary.
Air Emission Controls
Because previous investigations at the
McColl site indicated that the waste could
emit significant amounts of VOCs, organic
sulfur compounds, and SOg to the air, ex-
cavation could significantly affect workers
and the community.
For the trial excavation, the effect on
the community of this potential air emission
was mitigated by erecting a temporary
enclosure 60 ft wide, 160 ft long, and 26 ft
high over the center of the excavation
area. Before being released to the ambient
air, air from the encbsure was vented
through a sodium-hydroxide-based wet
scrubber and an activated-carbon adsorber
in series.
For the trial excavation, this potential
air emission effect on workers was miti-
gated by having workers wear Level B or
Level A protection at all times while inside
the enclosure.
Concentrations of SO, and THC were
continuously monitored before and after
the enclosure exhaust treatment system.
As part of a supplemental sampling and
analytical effort, sampling for speciation of
organic and reduced sulfur compounds
occurred at the stack inlet and outlet, at
the fence-line, and in the community.
These data are not reported, however,
because of invalidation by an EPA Audit.
Waste Characterization
Samples of excavated waste were ana-
lyzed to determine heat value and the
concentrations of selected constituents
(Table 2),
Toxicity characteristics of the raw tar
and char were determined by the Toxicity
Characteristics Leaching Procedure
(TCLP) and California Wet Test. No metal
constituents exceeded the regulatory limit
in either case. Benzene in the tar and
char waste exceeded the EPA TCLP limit
of 500 jig/L by more than a factor of 2.
Community Impact
Perimeter air was continually monitored
for SO2 and THC during this study.
Windspeed and direction were also con-
tinually recorded. This information was
obtained to comply with the Community
Contingency Plan, which mandates that
all site work be stopped if SO2 levels at the
perimeter exceed 0.5 ppm for 5 min or if
THC levels exceed 70 ppm for 30 sec.
These levels were never reached during
this study. The maximum 1-hr readings
obtained at any perimeter station in June,
Which was the period of highest emis-
sions from the waste, were Q.OB ppm for
SO2 and 21.9 ppm for THC.
Costs of Excavation and Tar
Processing
The costs for the field aspects of this
trial excavation work consisted of those
involved with the enclosure and encbsure
exhaust treatment system, actual excava-
tion labor and equipment, foam application,
tar processing, and air monitoring. Be-
cause much of the equipment for this
project (e.g., enclosure framework, scrub-
ber, and excavation machinery) was rented
on a monthly basis, total costs were com-
posed of the monthly machinery charges,
labor, and fixed costs required to mobilize
and demobilize. These costs are summa-
rized (Table 3) for the 2-mo duration of
the field work.
Table 3. Summary of Onsite Costs
Item Total Cost
Enclosure
Air exhaust control system
Foam vapor suppressants
Excavation'
Tar processing
Air monitoring
Total
$70,976
40,415
89,591
82,512
17,367
100, 160
$401,021
'Based on 18 days of excavation.
Conclusions
The overall goal of the trial excavation
was to obtain information about excava-
tion and waste-handling activities to sup-
port the selection of thermal destruction
as the preferred remedy and to aid In the
design of a thermal destruction remedy
after one is selected in a Record of Deci-
sion (ROD). An important question to an-
swer with information from the trial exca-
vation is whether the McColl waste can
be excavated with conventional equipment
without significantly affecting the commu-
Table2. Waste Characteristics, As-Received Basis
Mud Tar
Treated Tar
Char
Moisture, %
SuHur,%
Fixed Carbon, %
Ash,%
Benzene, ppm
Toluene, ppm
Xylene, pprn
Ethylbenzenef ppm
Heat Value, 8Mb
13.2
0,8
0.2
S2.9
<0.7
1,5
816
0.9
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nrty. Based on this goal, the following con-
clusions have been reached:
* Waste material was excavated with
conventional excavation equipment
without significant adverse effects
on the community.
Excavation under an enclosure is
technically feasible and allowed for
emissions generated during the
excavation activities to be controlled
with an enclosure air exhaust treat-
ment system consisting of a sodium
hydroxide wet scrubber and an ac-
tivated carbon unit.
Excavation and waste handling ac-
tivities are not technically feasible
without an enclosure and enclosure
exhaust treatment system at this
site.
The waste material was success-
fully treated to improve its handling
characteristic to allow easy process-
ing In a thermal destruction unit, if
desired.
The vapor-suppressing foam did not
perform as anticipated in control-
ling SO and THC emission within
the enclosure and cannot be ex-
clusively relied on to control emis-
sions during activity-related waste
disturbances.
Observations
These observations of activities that
occurred during the trial excavation are
qualitative in nature, and no qualitative
data exist to support them; however, they
represent best engineering judgment in
relation to activities related to the trial
excavation. It is believed that:
Community communication on this
project was effective and a neces-
sary part of the project. The com-
munity interaction was important to
the success of the trial excavation
and the success of the passive odor
and health effects survey conducted
by the California Department of
Health Services.
Excess water introduced into the
enclosure through the foaming ac-
tivities significantly affected opera-
tions within the enclosure. The ex-
cess water made the ground sur-
face slippery for both workers and
equipment.
Visual observation and qualitative
calculations determined that the
trench shield was a very effective
tool in minimizing the amount of tar
material that could seep into the
excavation area. It was also deter-
mined that the trench shield was
not needed to shore up the soils or
char material within the excavation
area.
Having workers in Level A protec-
tive gear adversely affected their
productivity and communication but
did not make excavation activities
unfeasible.
Lower airflow rates through the ac-
tivated carbon unit increased the
THC removal efficiencies. This
supports the theory that residence
time is a critical factor in the ability
of activated carbon to remove or-
ganic compounds in an air stream.
Contrary to original plans, EPA had
to move major equipment into and
out of the encbsure during opera-
tions. The community and workers
were not adversely affected from
opening the enclosure for short pe-
riods of time (under 1 hr) to allow
for efficient equipment movement.
The results of the tar processing
indicate the pug mill could effec-
tively process the char and mud
fractions of the McColl waste for
use In a thermal destruction remedy.
Because tar seeped into the exca-
vation area, approximately 100yd9
of material could not be replaced in
the excavation pit at the completion
of the project. This material was
stockpiled onshe in the staging area
under a plastic liner covered by
topsoil.
Under true field conditions (not re-
search-restricted conditions), the
excavation rating associated with
the equipment could be achieved.
The excavation rates achieved
during the trial excavation were ar-
tificially constrained to allow for data
collected and visual observations.
The excavation rates were also
constrained by unexpectedly high
S02 and THC emissions rates.
The observation camera was an
invaluable tool in observing/record-
ing activities that occurred within
the enclosure. The camera also al-
lowed all workers to be observed
from a health and safety standpoint.
Because of the camera, fewer em-
ployees were needed within the
enclosure; this allowed for more
efficient operations and reduced the
risk of employee accidents.
•US. Govwnmerrt Prtnling Office: WK—64M80«Q112
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The EPA Project Managers were J. A, McSorley, Air and Energy Engineering
Research Laboratory, Research Triangle Park, NC 27711; •/. Btovlna,
EPA Region IX, San Francisco, CA 94105; and J. Hubbard, Risk Reduc-
tion Engineering Laboratory, Cincinnati, OH 45268 (see betow).
The complete report, entitled "SITE Program Demonstration of a Trial Excava-
tion at the McCott Superfund Site, * (Order No, PB92-226 448/AS; Cost;
$35,00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
For further information, J. Hubbard can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
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EPA/540/SR-92/015
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