&EPA
www.epa.gov/research
EPA/600/F-17/286
science in ACTION
INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
SHC 3.62 ENVIRONMENTAL RELEASES OF OILS AND FUELS
Output 3.62.2 Tools for evaluating Impacts of Fuels/Oils for Use in Site Remediation,
Restoration and Revitalization.
Science Question: How can we better determine
the type, degree and extent of impacts of fuel and
oils spills on community public health and their
resources, especially those that are removed in
time and distance from the original contamination?
Output Description: This output provides tools to
help site managers and thereby communities to
better evaluate and predict the potential public
health impacts of fuels and oil spills. These tools
will assist in identifying and addressing impacts to
advance public health through prevention
measures and improved response technologies to
minimize impacts to land and water resources. The
work reported here builds on previous contaminant
fate and transport characterization work for fuels
and oils (Conmy and Weaver, 2016), which is
necessary to evaluate exposure to populations and
impacts to ecosystem services that potentially
impact human health and the environment. The
work involves assessment of appropriate metrics
for oil spiil response, remediation, restoration, and
revitalization, in the context of potential changes
due to various environmental factors. Three
specific tools are included in this output: (1) a
report on fate of diluted bitumen, (2) a model for
petroleum vapor intrusion, and (3) methods to
understand the association of private domestic
wells and underground storage tank sites.
(1) Report on the biodegradation and toxicity of
diluted bitumen crude oils to determine fate of
bitumen discharged in water.
Unconventional diluted bitumen (dilbit) oil products
present an increasing environmental concern
because of extensive transport in North America,
recent spills into aquatic habitats, and limited
understanding of environmental fate and toxicity.
Dilbits are blends of highly weathered bitumen and
lighter diluent oils that contain higher concentrations
of resins and asphaltenes, and lower levels of
saturates, with unique properties, including high
Figure 1. Dispersed oil in an experimental wave tank.
adhesion, and the potential for rapid weathering,
sinking and associating with sediments. Information
on biodegradation, toxicity, dispersion and fate of
dilbit is limited and warrants further study, particularly
given diversity in diluted bitumen types and
weathering state. Recent reviews produced by
federal agencies, the National Academies of Science,
academics and industry highlight the pressing need
to better understand the behavior and potential
impacts of dilbit spills over land and water. To
address knowledge gaps pertaining to the behavior
and fate of spilled diluted bitumen, the SHC Project
3.62 produced a report in 2017 summarizing
research on the dispersion effectiveness,
physical/chemical characterization, biodegradation
and toxicity of two types of diluted bitumen- Cold
Lake Blend and Western Canadian Select. Findings
support Regions and States for emergency response
planning with respect to oil spills under the Oil
Pollution Act and National Oil and Hazardous
Substances Contingency Plan. These efforts have
also been published in Deshpande, 2016;
Deshpande et al., 2017; Barron et al., 2017.
(2) User's Guide for PVIScreen Model including
distributable software.
indoor air contamination from subsurface vapors is a
potential pathway at contaminated sites. At leaking
underground storage tank sites where petroleum
fuels have been released, there may be suspected or
actual impacts to indoor air of residences or
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business. Assessing these sites is difficult for both
technical and social reasons, and models can play a
part in site decision making. Models, are limited,
however, in that all their needed parameters are not
measured at typical field sites and unless indoor air
measurements are made, calibration data are
unavailable. The PVIScreen model was developed to
provide a practical tool for assessing petroleum vapor
intrusion while accounting for uncertainty in the
unmeasured parameters. This feature is
accomplished by a "Monte Carlo" simulation whereby
the 1000 scenarios are constructed and evaluated by
systematically using parameters representative of
typical ranges of variability.



...

Figure 2. PVIScreen schematic of petroleum vapor intrusion
scenario.
The results are presented in a way that is similar to a
weather forecast, as an outcome (exceeding a health
screening level) with an associated probability. Site
managers can use these results where a line of
evidence is needed to support/reject the need for
indoor air sampling.
The model and user's guide have undergone internal
and external review by stakeholders from state
agencies and industry. Final changes have been
made to the software in preparation for a public
webinar in 2018 and distribution of the model.
(3) Mapping Private Wells and Site Densities of
Underground Storage Tank Sites
Figure 3. Estimated density of private domestic well use in
Oklahoma (darker equals more use).
For protecting drinking water supplies, the locations
of areas with reliance on private domestic wells
(hereafter referred to as "wells") and their relationship
to contaminant sources need to be determined. A key
resource in the U.S. was the 1990 Census where the
source of domestic drinking water was a survey
question. Because the question was dropped from
later censuses, two methods are developed to update
estimates of the areal density of well use using
readily accessible data. The first uses well logs
reported to the states and the addition of housing
units reported to the Census Bureau at the county,
census tract and census block group scales. The
second uses housing units reported to the Census
and an estimated well use fraction. To limit the scope
and because of abundant data, Oklahoma was used
for a pilot project. The resulting well density
estimates were consistent among spatial scales, and
were statistically similar. High rates of well use were
identified to the north and east of Oklahoma City,
primarily in expanding cities located over a productive
aquifer. In contrast, lower rates of well use were
identified in Oklahoma's second largest city, Tulsa,
attributable to a lack of suitable groundwater. Thus
rural areas are more likely to have a public water
system in the Tulsa area. High densities of private
domestic well use may be expected in rural areas
without public water systems, expanding cities and
suburbs, and legacy areas of well usage. The
completeness of reported well logs was tested by
counts from neighborhoods with known reliance on
wells which showed reporting rates of 20% to 98%.
Well densities in these neighborhoods were higher
than the larger-scale estimates indicating that locally
high densities typically exist within analysis units. A
Monte Carlo procedure was used to estimate that
27% of underground storage tanks in Oklahoma were
within 300 m (1,000 ft) of one or more water supply
wells. Work is continuing to extend these methods
and results to the entire United States
REFERENCES:
Barron, Conmy, Holder, Meyer, Wilson, Principe, Willming
(2017) Toxicity of Cold Lake Blend and Western Canadian Select dilbits to
standard aquatic test species. Chemosphere (in review).
Conmy, Barron, SantoDomingo, Deshpande (2017)
Characterization and Behavior of Cold Lake Blend and Western Canadian
Select Diluted Bitumen. US EPA internal report, 52p.
Conmy, Weaver, (2016), Tools for Improved Characterization,
Response, and Remediation of Oil and Fuels to Improve Emergency
Response and Other Clean Up Activities, U.S. EPA. Science in Action.
Deshpande (2016) Degradability of Diluted Bitumen.
University of Cincinnati, Master's Thesis, Cincinnati, OH, USA, 72 pp.
Deshpande, Sundaravadivelu, Campo-Moreno, Techmann,
Santo Domingo, Conmy (2017) Microbial degradation of Cold Lake Blend
and Western Canadian Select dilbits in freshwater. J. Hazardous
Materials (in review).
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Weaver, Davis (2016) Petroleum Vapor Intrusion Model
Assessment with PVIScreen, EPA report, EPA/600/R-16/175.
Weaver, Murray, Kremer (2017) Estimation of the Proximity
of Private Domestic Wells to Underground Storage Tanks in Oklahoma,
Science of the total Environment, 609, 15
Weaver, Murray, Kremer (2017) Proximity of Private
Domestic Wells to Underground Storage Tanks: Oklahoma Pilot Study,
EPA/600/R-17/209.
CONTACT: Robyn Conmy, 513.569.7090, conmv.robvn|S)epa.gov or Jim
Weaver, 580.436.8550, weaver.iim|S)epa.gov: ORD NRMRL
www.epa.gov/ord
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U.S. Environmental Protection Agency
Office of Research and Development

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