United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/086 Dec. 1987
Project Summary
Field Assessment of Air
Emissions and Their
Control at a Refinery Land
Treatment Facility
B. M. Eklund, T. P. Nelson, and R. G. Wetherold
A field assessment was performed to
measure the emissions of volatile
organics from a petroleum refinery land
treatment site. As part of this study,
the emissions of total volatile organics
from surface-applied and subsurface-
injected oily sludge were measured
over a five-week period. The effect of
soil tilling on the emissions was also
monitored.
Volatile organic emission rates were
measured using the emission isolation
flux chamber method. Emission rates
of carbon dioxide and methane were
also measured for use in evaluating and
estimating apparent biodegradation
rates. Soil samples were collected
during the test periods to determine soil
properties, oil levels and microbe
count. Soil surface and ambient
temperatures inside the flux chambers
were also measured throughout the
test periods to determine their influ-
ence on emission rates.
From the measurements, the emis-
sion rates of total volatile organics, as
well as the emission rates of selected
individual volatile organic species,
were estimated over the five-week
period. The amount of oil biodegrada-
tion was estimated from carbon dioxide
evolution rates and oil disappearance
from soil samples over the test period.
The measured volatile organics emis-
sion rates and the emission rates of
selected species were compared to the
rates predicted with The Thibodeaux-
Hwang land treatment model.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
This Project Summary was devel-
oped by EPA's Hazardous Waste
Engineering Research Laboratory,
Cincinnati. OH. to announce key
findings of the research project that is
fully documented in two separate
volumes of the same title (see Project
Report ordering information at back).
Introduction
The Office of Air Quality Planning and
Standards (OAQPS) of the U.S. Environ-
mental Protection Agency (EPA) is devel-
oping standards for controlling emissions
from hazardous waste treatment, storage
and disposal facilities (TSDFs). The
purpose of these regulations is to protect
human health and the environment from
impairment by emission of volatile
organic compounds (VOCs*) and partic-
ulate matter. The Hazardous Waste
Engineering Research Laboratory
(HWERL) has the responsibility of pro-
viding technical support to OAQPS in the
area of atmospheric emissions determi-
nation from hazardous waste manage-
ment. Part of the research in the HWERL
program involves the study and assess-
ment of emission control techniques
which are applicable to TSDFs.
In the current study, the emission
characteristics of the land treatment of
oily sludges by surface application and
subsurface injection techniques were
evaluated. The results of this assessment
have increased the understanding of
volatile organics emissions from land
treatment disposal facilities. The subsur-
"VOCs are defined in this study as those purgeable
volatile compounds determined by a purge-and-trap
technique.
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face injection technique was selected for
this study because the technique is
believed to represent a potentially major
type of volatile organics emission control
at TSDFs.
To assess the effectiveness of subsur-
face waste injection as an emission
control technique, a field study was
performed at the land treatment facility
located at the Chevron, USA refinery in
El Segundo, California. The major objec-
tives of the study at this site include the
following:
• To determine the percentage of vola-
tilized organics as a function of the
applied purgeabale organics and of
the applied oil;
• To estimate the emissions of applied
volatile organics from the test plots
for the five-week testing period and
annually for the entire land treatment
facility;
• To determine the effectiveness of
subsurface injection in reducing
volatile organic emissions from land
treatments by comparing the mea-
sured emission rates from the two
application methods;
• To determine the extent of oil degra-
dation and/or measurable biological
activity;
• To determine the effects of various
environmental and operational
parameters on emission rates and
emission rate measurements, includ-
ing those due to the emission meas-
urement procedure; and
• To compare the measured emission
rates to those calculated using the
Thibodeaux-Hwang predictive emis-
sion model.
Approach
The land treatment area at the Chev-
ron, El Segundo refinery covers approx-
imately 42,000 square meters (10 acres).
Three test plots, each approximately 420
square meters (0.1 acre) in area, were
located side-by-side at one corner of the
facility. The area containing the test plot
has been in land treatment service for
several years.
Experimental Design—The test design
was a synthesis of two sampling strate-
gies for obtaining emission measure-
ments: totally randomized sampling over
the test plots and semi-continuous
sampling at a single location in each plot.
Three test plots were used in this study.
Sludge was surface-applied to one plot
(Plot A) and subsurface-injected on
another plot (Plot C). In between these
two plots was a third plot (Plot B), and
no sludge was applied to this plot during
the test period. Plot B served as a
baseline or control plot. Each plot was
divided into 21 equal segments to provide
for randomized sampling.
Sampling was performed during the
first, third and fifth weeks of a five-week
period. Samples were collected in the
morning and afternoon. On two days,
samples were collected immediately
before dawn so that nighttime emissions
could be estimated.
Samp/ing Procedures—The main sam-
pling technique employed at this site
involved the direct measurement of
emissions using the emission isolation
flux chamber. A diagram of the flux
chamber is shown in Figure 1. The flux
chamber is placed on the emitting
surface. Clean, dry air is passed through
the chamber at a controlled and meas-
ured rate. The concentration of the
specie(s) of interest is measured at the
outlet of the chamber. The emission rate
of the measured species(s) from the
enclosed surface can then be calculated
from the flow rate and concentration in
the gas.
Liquid grab samples of the sludge and
the service water used to irrigate the soil
were collected. Samples of soil were also
collected periodically during the testing.
Temperature
Readout
Type K thermocouples were used to
monitor the air and soil temperatures
both inside and outside of each flux
chamber.
Analytical Procedures—-The on-site
analyses were limited to gas-phase
analyses of the air samples collected in
gas-tight syringes from the outlet of the
flux chambers. A Byron Instruments
Model 401 total Hydrocarbon (THC)
analyzer was used to determine the
concentrations of total hydrocarbons
(THC), C02 and methane in the effluent
air samples from the flux chamber.
The off-site analyses included the
chemical speciation of the flux chamber
air samples collected in stainless steel
canisters and of the liquid sludge and
water samples collected at the land
treatment site. The oil, moisture, and
microbe levels in the soil were also
determined, as were the physical prop-
erties of the soil samples.
The oil, water and solids content of the
sludge samples were determined by a
method developed for this purpose by
Chevron Research Corporation. This
method is called the Modified Oven
Drying Technique (MOOT). The oil and
grease content of the soil samples was
determined by EPA Method 413.1.
Standard methods were used to deter-
mine the bulk density, particle density,
total porosity, moisture content and
particle size distribution of the soil
samples.
Sludge Application—The sludge was
applied as evenly as possible to the
Thermocouple
Syringe/Canister
Sampling Port
Stainless Steel
or Plexiglas
Figure 1. Cutaway side view of emission isolation flux chamber and sampaling apparatus.
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urface-applied Plot A and to the
.ubsurface-injected Plot C. The sludge
was injected subsurface using an 8000
liter (50-barrel) capacity injector vehicle
equipped with four separate injector
tines. The waste was injected 15-28 cm
(6-11 inches) below the surface. The
average waste loading was 1.4 x 10*
kg/plot, assuming equal application
rates for both plots. All three plots were
tilled with a disk tiller pulled behind the
tractor during the sludge application.
Emission sampling with the flux
chambers was started immediately after
application and continued for four days.
Emission sampling was performed dur-
ing two other four-day periods in the third
and fifth weeks following application.
Each plot was tilled 2-3 times per week
during the five-week test period. The
plots were also irrigated with water once
between the first and second sampling
periods and three times between the
second and third sampling periods.
Emission Estimates—Based on the
emission measurements performed in
this study, total-VOC emissions were
estimated for the individual test plots for
a five-week period. To do this, nighttime
emissions were estimated by interpolat-
ng between late afternoon and early
morning measurements. Daily emissions
for days on which no measurements
were taken were determined by interpo-
lating between days when emissions
were measured.
Annual emissions were also estimated
for the whole facility so that emissions
reductions potential for emissions con-
trols could be determined. To estimate
annual emissions, five week test-plot
emissions were extrapolated, to the
whole facility by accounting for facility
waste application rates, applicaticn
methods and surface area.
Emission Modeling—Instantaneous
emission rates were calculated using the
Thibodeaux-Hwang model. Total-VOC
emissions were calculated using average
physical and chemical properties for
various classes of volatile compounds
(e.g., volatile aromatics), properties of the
test plot soil and site-specific environ-
mental parameters. Similarly, the emis-
sion rates of the 12 compounds studied
individually were calculated based on
their individual physical and chemical
properties.
Results and Discussion
The following site-specific findings
were obtained from this study.
Total Volatile Organic Emission
Rates
The average emission rates for each
plot over the five-week test period were
47.1, 6.16, and 53.9 //g/m2-s of volatile
organics for the surface applications
(Plot A), background (Plot B), and sub-
surface application (Plot C) plots, respec-
tively. The instantaneous emissions from
each of the three plots were as high as
370.7, 38.5, and 324.9 //g/m2-sec,
respectively.
The emission rate decreased approx-
imately exponentially with time after
application for each plot. Comparing the
averaged measured emission for the first
week of sampling to the third and fifth
(final) weeks of sampling, the emission
rates decreased 93%, 86%, and 91% for
the surface application, background, and
the subsurface application plots, respec-
tively. The weekly estimated emission
rates are shown graphically in Figure 2.
The five-week estimated cumulative
emissions for Plots A, B, and C were
33.3, 5.2, and 39.0 kg, respectively.
It was estimated that the ratio of
volatile organics emitted over five weeks
to purgeable organics in the waste was
0.30 for Plot A and 0.36 for Plot C. The
ratio of volatile organics emitted over five
weeks to the mass of applied oil was
estimated to be 0.012 for Plot A and
0.014 for PlotC.
The measured emission rates were
found to be related to the ambient air
temperatures above the soil surface. This
resulted in a significant diurnal effect in
emissions. For the two occasions when
sampling was conducted before dawn,
the average measured emission rate for
the "half-day" (i.e., four-hour) period was
lower than the average of the half-day
averages for that week for each plot. For
Week 1, the decrease was 75%, 56%,
and 87% for Plots A, B and C, respec-
tively. For the second week of sampling,
the decrease was 75%, 54% and 59%
for Plots A, B and C, respectively.
Subsurface Injection as an
Emissions Control Technique
The application method as practiced at
this refinery did not appear to have a
large effect on the emissions. Imme-
diately after sludge application and
before the first tilling, the cumulative
measured emissions from the surface
application plot were slightly greater
than those from the subsurface applica-
tion plot. After the first tilling episode
(two days after the initial application), the
cumulative measured emissions seemed
to be slightly greater for the subsurface
application plot throughout the
remainder of the test period. The total
cumulative measured emissions were
Total Est. Emissions/Week
A=Surf. B-Bkg. C=Subsurf.
to
§
Figure 2. Total weekly estimated emisisons for each plot.
3
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14% greater from Plot C than Plot A.
Similarly, the estimated total emissions
from Plot C (39.0 kg) were 17% greater
than the total for Plot A (33.3 kg) for the
five-week test period.
Because the difference between
cumulative emission rates for Plots A
and C were small and were comparable
to the uncertainties in emissions rates
themselves, it is not possible to draw
conclusions regarding the relative emis-
sion characteristics of the two applica-
tion plots. However, any difference did
not appear to be significant.
Emissions of Individual
Compounds
The emissions of 12 selected individual
compounds consisting of alkanes,
alkenes and aromatics were also studied
in detail. The dozen individual com-
pounds examined behaved in the same
manner as the total volatile organics. The
emissions rates decreased with time,
increased after tilling, and showed
diurnal fluctuations. However, the appli-
cation method had a greater effect on
the individual compounds than for total
volatile organics. Also, a greater percen-
tage of the applied individual compounds
was emitted than for total volatile
organics. The difference between the
average emissions values and those of
the 12 selected compounds is thought
to be due to the differences in volatilities
of the 12 selected compounds and the
average volatility of the oily sludge.
Biodegradation and Oil
Disappearance
Radian measurements indicated that
little or no biodegradation of the applied
oil was observed. No methane was
detected, implying that no anaerobic
degradation occurred. Significant quan-
tities of possible products of partial
degradation were not detected. Because
of the scatter in the data, neither a
change in microbial population levels nor
a decrease in oil content in the soil could
be discerned. The measured carbon
dioxide (COz) values were at near back-
ground levels. Assuming all C02 mea-
sured was due to complete aerobic
degradation, less than 3% of the applied
oil was completely degraded over the
five-week test period.
Chevron analyzed more soil samples
using a recently developed analytical
technique. One or both of these factors
contribute to more precise measuremen
of the variation of oil content with time
The Chevron results appear to indicat
a decrease in oil levels in the soi
However, even these data show signif
icant scatter; only one of the fou
monitored sampling points exhibited •
change in oil content which had greate
than a 95% certainty of being nonzero.
Emissions Model
The Thibodeaux-Hwang model for Ian
treatment facilities was found to predic
mean emission rates that were general!
higher than those actually observed, bu
which agreed to within an order c
magnitude. The model predicts an expo
nential decay in emissions over tim
which approximately agrees witl
observed changes in emissions at th<
site.
B. M. Eklund, T. P. Nelson, and R. G. Wetherold are with Radian Corporation,
Austin, TX 78766-0948.
Benjamin L. Blaney is the EPA Project Officer (see below).
The complete report consists of two volumes entitled "Field Assessment of
Air Emissions and Their Control at a Refinery Land Treatment Facility:"
Volume I (Order No. PB 88-1'24540'/AS; Cost: $32.95, subject to change).
Volume II (Order No. PB 88-1245577AS; Cost 32.95, subject to change).
The above reports will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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