c/EPA
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P. 0. Box 93478
Las Vegas, NV 89193-3478
April 1994
The Environmental Monitoring
Systems Laboratory - Las Vegas
Research,
Innovation
and
Technology Support
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U.S. Environmental Protection Agency, Environmental Monitoring Systems Laboratory - Las Vegas
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TABLE OF CONTENTS
INTRODUCTION TO THE TECHNOLOGY SUPPORT CENTER
1. Technology Support Center
CURRENT FIELD SUPPORT TECHNOLOGIES
1. Soil-Gas Measurement
2. Field Portable X-Ray Fluorescence
3. Mobile Mass Spectrometer
4. Geophysics: A Key Step in Site Characterization
COMPUTER SOFTWARE
1. Assess: A Quality Assessment Program
2. Hypertext: A Showcase for Environmental Documents
3. Scout: A Data Analysis Program
4. Geo-EAS: Software for Geostatistics
5. Geophysics Advisor Expert System
6. Cadre: A Data Validation Program
REMOTE SENSING TECHNOLOGIES
1. ARC/INFO Concepts and Terminology
2. Accessing Geographic Information Systems (GIS) Technology
3. Geographic Information Systems: An Overview
4. GIS Planning Process
5. Remote Sensing in Environmental Enforcement Actions
6. Topographic Mapping for Environmental Assessment
7. Remote Sensing Support for RCRA
8. Wetlands Delineation for Environmental Assessment
9. Photogrammetry tor Environmental Measurement
10. Global Positioning System (GPS) Technology
11. Historical Maps and Archiving for Environmental Documentation
RADIATION MONITORING
1. Field Screening Methods for Radioactive Contamination
2. Internal Dosimetry for Radionuclides in Humans
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ENVIRONMENTAL MONITORING AND ASSESSMENT PROGRAM (EMAP)
1. Colorado Plateau Pilot Study
2. And Ecosystems: The Spectral Indicator
SPECIALTY AREAS
1. Immunochemistrv for Environmental Monitoring
2. High Resolution Mass Spectrometer
3. Open Path FT-IR Use in Environmental Monitoring
4. Continuous Monitoring with Purge-and-Trap Gas Chromatography
5. UV-Vis Luminescence in Field Screening and Monitoring
6. Robotics Technology in Environmental Sample Preparation
7. Guidance for Characterizing Heterogeneous Hazardous Wastes
8. Correct Sampling Using the Theories of Pierre Gy
9. Special Analytical Services
10. Performance Evaluation Samples
11. Monitoring Airborne Microorganisms
12. Biosensors for Environmental Monitoring
EMSL-LV INNOVATIVE TECHNOLOGY
1. Field-Portable Scanning Spectrofluorometer
2. Immunochemical Analysis of Environmental Samples
ISSUE PAPERS
1. Survey of Laboratory Studies Relating to the Sorption/Desorption of
Contaminants on Selected Well Casing Materials
2. Potential Sources of Error in Ground-Water Sampling at Hazardous Waste
Sites
3. Soil Sampling and Analysis for Volatile Organic Compounds
4. Characterizing Soils for Hazardous Waste Site Assessments
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United States
Environmental Protection
Agency
c/EPA
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
EPA 600/M-91/011
April 1991
The Environmental
Monitoring Systems
Laboratory - Las Vegas
The Environmental Monitoring
Systems Laboratory - Las
Vegas (EMSL-LV) is one of
EPA's twelve national re-
search laboratories in its
Office of Research and
Development. Over 200 EPA
employees and 300 on-site
contractor personnel work at
the EMSL-LV, which has an
annual operating budget of
about $40 million. Its mission
is to develop, evaluate, and
apply methods and systems
for monitoring the environ-
ment.
The Laboratory was estab-
lished in 1955 as a U.S.
Public Health Service labora-
tory with responsibility for
monitoring radioactivity in
public areas around the
Nevada Test Site and other
nuclear explosive test sites.
Environmental radiation
monitoring and research
activities associated with the
U.S. Atomic Energy
Commission's nuclear testing
program were the sole pro-
grams conducted by the labo-
ratory through the 1960's.
This activity included a
radiation biology research
program. When the Environ-
mental Protection Agency was
created in December 1970,
the Laboratory became a part
of the new Agency with an
expanded mission to develop
monitoring techniques for a
variety of environmental pol-
lutants and conduct environ-
mental studies nationwide. In
1972, the Environmental Pho-
tographic Interpretation
Center (EPIC) in Warrenton,
Virginia, became a part of the
Laboratory as an eastern
facility for remote sensing
support to EPA Regional and
Program Offices.
The EMSL-L V Executive Center at night; part of a complex of buildings located on the campus of the University of Nevada-Las Vegas.
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I
Laboratory Programs
A continuing theme for the
Laboratory has been re-
search on integrated expo-
sure of man to chemical and
radiological pollutants
through multiple environ-
mental pathways. Major in-
vestigative and technology-
developmental areas include:
Major Program Areas
1) Advanced Analytical Chemistry
2) Field Monitoring
5) Human Exposure Assessment
6) Environmental Status and Trends
Unique Areas of Expertise
8) Subsurface Monitoring
9) Geographic Information Systems
10) Environmental Radiation Assessment
11) Geostatistics
Special Projects
¦
3) Monitoring Network Design
4) Field and Laboratory Quality Assurance
I
7) Remote Sensing (Active and Passive)
¦
¦
mass spectrometry, Fourier and inductively-coupled
transform infrared spectros- plasma spectroscopy are
copy, gas chromatography developed and evaluated.
Advanced Analytical Methods Research
Advanced Analytical
Chemistry
Measurement of an ever-in-
creasing number of organic
and inorganic contaminants
in complex environmental
matrices, at ever-increasing
levels of sensitivity, has re-
quired the development and
evaluation of innovative
techniques for sample
extraction and analysis.
Advanced techniques such
as liquid chromatography,
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turnaround data that can
result in major cost savings
and expedite the cleanup
process. These instruments
and methods will enhance
EPA's ability to manage risks
posed by hazardous waste
sites.
Field Monitoring
Laboratory evaluation and
field validation of existing and
emerging technologies for off-
site measurement of toxicants
at or around hazardous waste
sites is the central activity of
the advanced field monitoring
methods program. This
program addresses the need
for rapid, low-cost field
methods to support hazard-
ous waste site monitoring and
characterization activities.
The costs of site characteri-
zation are a direct result of
sampling, analyses and
associated quality assurance
activities required to deter-
mine the suitability of data for
environmental decision
making. Portable x-ray fluo-
rescence spectrometer and
gas chromatograph methods,
and highly specific chemical
sensors and immunochemical
test kits are capable of
yielding immediate or quick
Field Portable Test Kit for Immunochemical Environmental Monitoring
Monitoring Network
Design and
Geostatistics
Monitoring systems design
and monitoring statistics are
rapidly advancing fields be-
cause of readily available
personal computers and their
inexpensive computing
power. At the same time, the
high cost of collection and
analysis of environmental
samples places a premium
on efficient and effective
study design and data
interpretation. The monitoring
statistics program is develop-
ing data-analysis techniques
for more defensible decision
making, computerized spatial
simulation for sampling plan
design and evaluation,
kriging software for personal
computers, and multivariate
methods for spatial pattern
recognition. Each of these
activities is aimed at provid-
ing practical help for environ-
mental investigators. For
example, spatial data analy-
sis can provide maps of sites
showing isopleths of probabil-
60 82
Surface Estimated by Kriging, with Corresponding Contour Map
3
ity exceeding a selected
contaminant
concentration.
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Field and Laboratory Quality Assurance.
Field and Laboratory
Quality Assurance
The Laboratory serves as the
Agency's center for analytical
laboratory quality assurance.
Properly validated test
methods are developed, and
guidelines are prepared to
enhance the Agency's ability
to obtain reliable sample
analyses through commercial
laboratories. Studies are
conducted to evaluate the
performance of these labora-
tories and to determine the
precision and accuracy of
analytical protocols. In the
1980's the Laboratory
assumed national leadership
for monitoring and quality
assurance aspects of the
Agency's hazardous waste
and pesticides programs.
Human Exposure
Assessment
Human exposure assess-
ment provides critical infor-
mation required to make risk
estimates for environmental
pollutants. Exposure assess-
ments are conducted by
using predictive methods
(modeling), direct measure-
ments (monitoring), or by the
use of reconstructive tech-
niques (biomarkers). Labora-
tory projects utilizing the
predictive methods include
the evaluation and validation
of indoor air models and the
development of a model to
estimate the exposure of
humans to benzene. Projects
utilizing the direct measure-
ment approach include the
measurement of benzene
concentrations in various
microenvironments and the
use of personal exposure
monitors (PEMs) to measure
the exposure of nitrogen
oxides to humans. Recon-
structive approaches for ex-
posure assessments are
being evaluated for possible
inclusion into future monitor-
ing programs. These include
the use of DNA adducts,
protein adducts (hemoglobin
and serum albumen) carrier
proteins (e.g., metal-
lothionein), receptors, conju-
gation systems (e.g., glu-
tathione), porphyrin ratio
changes, and lesion-specific
endonculeases. In addition,
biotechnology monitoring
guidelines are being devel-
oped for the release of ge-
netically engineered microor-
ganisms (GEMs) in agricul-
tural experiments. Emphasis
is being placed on sample
collection procedures,
comparison of sample types,
determination of aerosolized
bacterial half-life rates and
field study designs to monitor
GEMs.
Developing Human Exposure Models for Use in Exposure
Assessment
4
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Ecological Monitoring
The Laboratory is participat-
ing in the Agency's Environ-
mental Monitoring and As-
sessment Program (EMAP),
a national research program
to prevent unwanted or
irreversible damage to the
nation's ecosystems. EPA
must know the current status
of the ecosystem, be able to
determine trends in health or
deterioration, and be in
position to regulate environ-
mental pollutants in order to
protect these systems. The
national research will clas-
sify, characterize, and moni-
tor status and trends of
important ecosystems and
their subclasses. The moni-
toring efforts specifically
focus on conditions over
periods of years to decades.
The EMSL-LV, using ad-
vanced monitoring methods,
is determining status and
trends in terrestrial ecosys-
tems, specifically forests,
agroecosystems, grasslands,
and deserts, Also, the
Laboratory has general
EMAP responsibility for
conducting initial ecosystem
characterization, providing
remote sensing support,
providing guidance and
support for field logistics and
quality assurance, and for
developing and implementing
a distributed data base man-
agement system.
Monitoring the Status of an Ecosystem
Remote Sensing
(Active and Passive)
In the1970's, the application
of aerial photography and
scanner imagery technologies
for environmental assess-
ments became an important
Laboratory program. The
Laboratory's aerial photogra-
phy interpretation facilities in
Las Vegas and its branch in
Warrenton, Virginia, became
EPA's center for environ-
mental monitoring using
High Resolution
Satellite Imagery
Applications:
overhead imagery from
aircraft and satellites. Appli-
cations of this technology
have included the detection
of waste discharges into wa-
terways and harbors, the
location of waste disposal
sites on land, lake-water
quality management, wetland
delineation, erosion identifi-
cation and other types of
surface degradation, and
quantifying locations of envi-
ronmental impacts associ-
ated with land-use practices.
As the EPA's center for this
type of monitoring technol-
ogy, much of the Laboratory
work in this area involves col-
lecting and analyzing aerial
imagery to support environ-
mental regulation compliance
investigations by EPA's
Regional Offices.
Left, High Spatial
Resolution - Urban
Mapping.
Right, High Spectral
Resolution -
Vegetation Analysis
5
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Remote Sensing
(continued)
Aircraft-borne laser-based
remote sensing devices are
being developed and applied
for the monitoring of urban
and regional scale environ-
mental problems. The
primary laser-based tool for
urban or regional air quality
assessment is an airborne
aerosol lidar, which is used to
study pollutant layer struc-
tures and atmospheric mo-
tions influenced by complex
terrain and coastal environs.
Another lidar device under
development will allow for the
detailed, concurrent meas-
urement of ozone, sulphur
dioxide, and perhaps nitrogen
dioxide in the atmosphere. In
anticipation of increased
monitoring requirements, a
feasibility study has been
initiated to identify and
evaluate remote sensing
techniques for safely monitor-
ing toxic and hazardous
pollutants from a distance.
The related technology of
airborne laser fluorosensing
is used to measure a number
of water quality indicators in
lake, river, and estuarine
waters. These include
chlorophyll a concentration,
which is an indicator of phyto-
plankton density; dissolved
organic carbon (DOC), which
is an indicator of the overall
level of dissolved organic
matter; and the optical
attenuation coefficient, which
is closely related to water
clarity. Research is being
directed to detecting and
mapping algae blooms which
can create toxic water
conditions in lakes.
Computerized Interpretation ot Airborne Laser-Based Data
Gathering
Subsurface Monitoring
EMSL-LV is conducting
ground-water monitoring
methods research to test and
improve methods or proce-
dures for detecting contami-
nation of ground water. Sub-
surface monitoring methods
are also under development
for detecting pollutants in the
unsaturated zone above the
ground-water table, and for
collecting soil gases to detect
volatile subsurface pollut-
ants. Geophysical methods
such as ground-penetrating
radar and geochemical
detection methods are tested
and developed for mapping
near-surface contaminant
plumes. Both surface-based
and downhole methods are
examined for the more
difficult problem of mapping
deeply buried contaminant
plumes associated with
injection wells. Advanced
technologies such as
downhole pollutant detection
with light-activated optrodes
at the end of an optical fiber
eliminate the need for exten-
sive well-drilling to collect
water samples. Other re-
search is conducted to
develop leak detection
devices for monitoring
underground storage tanks
used for gasoline and other
chemicals.
Geophysical Sensing to Detect Substance Contaminants
6
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Geographic Information
Systems
This computer-based tech-
nology combines data and
automated cartography to
map data gathered from field
surveys, remote sensing
instruments, and other
information such as census
data on population distribu-
tion. Using a GIS, the envi-
ronmental analyst can display
and overlay "maps" of these
data layers on a video
monitor screen and conduct
extensive calculations and
operate mathematical models
of environmental conditions.
These types of analyses are
important to the EPA be-
cause they represent a com-
puter-based "tool box"
available to identify and
model pollutant threats
to human populations
and ecosystems.
EMSL-LV is the lead Labora-
tory for GIS research and
development to ascertain how
GIS technology will fit into the
assessment and enforcement
activities of the Agency.
The GIS research
mission is being ad-
vanced through a
series of pilot
projects to
demon-
strate the technology for ex-
amining hazardous waste dis-
posal sites, wetland areas, air
pollution and ground-water
contamination situations.
SAMPLE SITES
WASTES
ROADS
HYDROLOGY
SOIL/WATER
CHEMISTRY SAMPLES
BUILDINGS
TOPOGRAPHY
DRAINAGE BASINS
SOILS
Hazardous Waste Site
Geographic Information Systems (GIS) Data Layers
Environmental Radiation
Assessment
The Laboratory's radiation
monitoring program provides
the framework for document-
ing radiation exposures of
populations living near the
Nevada Test Site (NTS) and
other nuclear test sites.
Mobile monitoring teams are
deployed around the NTS
during nuclear test periods. If
radioactivity is released, these
teams are prepared to work
with local officials in directing
protective actions, including
evacuation of residents, if
necessary. Air and ground-
water sampling networks
measure off-site radiation
levels on a continuing basis.
Programs for sampling milk,
cattle, and wildlife detect inad-
vertent contamination. Ther-
moluminescent dosimeters, in
place at about 130 fixed loca-
tions in addition to those worn
every day by approximately
50 off-site residents, measure
accumulated radiation expo-
sure levels. The Laboratory
also operates a whole-body
counter that measures levels
of natural and man-made
radionuclides in bone, tissue,
and internal organs of resi-
dents living around the NTS.
In cooperation with the U.S.
Department of Energy, the
Laboratory has established 18
Community Monitoring Stations
around the NTS and placed
them under the supervision of
local residents. The radiation
data, collected every five
minutes from solar-powered
gamma radiation detection in-
struments, is transmitted to
the Laboratory via satellite
relay. A visual readout at the
station allows local residents
to observe exposure level
measurements at any time.
Community Radiation Monitoring Station
7
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Special Projects
The Laboratory has, over the
years, undertaken a number
of special projects utilizing its
broad monitoring capability.
Examples include the emer-
gency radiation monitoring
program for the Three Mile
Island nuclear power reactor
incident, the National Lake
Eutrophication Survey, Love
Canal contamination studies,
Missouri dioxin studies, and
the National Surface Water
Survey and Direct Delayed
Response Project as a part of
the EPA responsibility under
the Acid Precipitation Act of
1980.
Technical support, either in
the form of technology
transfer (training personnel in
other EPA offices or states on
how to use EMSL-LV technol-
ogy) or technical assistance
(helping others conduct
environmental studies), is
provided in all of the program
areas described earlier. For
example, the Laboratory was
assigned the responsibility for
designing the quality assur-
ance program for EPA's
research project to evaluate
bioremediation enhancement
for the (Valdez) Alaska oil
spill.
EMSL-LV, 944 East Harmon Avenue, Las Vegas NV 89119
PRINTED ON RECYCLED PAPER
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5v5;err;s Laocra'orv
P'O Box 93478
Las Vegas NV 89193-3478
Technology
Support
Center
i EMSL-LV
| Technology
: Support Center
c/EPA
INTRODUCTION
nrvrcnrrertai r.'G:ec::cn
Agency
TECHNOLOGY SUPPORT PROJECT
The U.S. EPA maintains
Technical Support Centers in
five laboratories operated by
the Office of Research and
Development (ORD). These
Technical Support Centers
are dedicated to serving the
EPA Regions by supplying
high-quality, quick-response
technical services when the
scope of work is beyond the
technical capabilities of local
contractors.
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) has
an active Technical Support
Center (TSC) that responds
to requests from the Regions.
The TSC began in 1987 and,
originally, specialized in
Superfund support to Reme-
dial Project Managers
(RPMs) and On-Scene
Coordinators (OSCs). Since
1991, RCRA technical
support is available too.
The EMSL-LV TSC special-
izes in sampling and monitor-
ing technologies, quality
assurance, soil and ground
water sampling, special
analytical services, and
radiation monitoring. This
diversity of expertise allows
the TSC to work with Re-
gional personnel throughout
a site characterization event,
from planning and design to
analysis and data interpreta-
tion.
In addition to direct technical
support, the EMSL-LV TSC
provides technical communi-
cation to the Regions through
the Technology Transfer
Project. Fact sheets, a
bimonthly newsletter entitled
"The EMSL-LV Bulletin", and
various presentations,
demonstrations, and poster
sessions help to keep
Regional personnel up to
date with the services
available through the TSC.
REGIONAL
REQUESTS
When RPMs/OSC or RCRA
Project Officers require
assistance through the
EMSL-LV TSC, they contact
the manager by phone or by
letter. Before any work is
committed, a written request
must be made. The TSC
manager determines the
ability to meet the demands
of the request and contacts
the technical staff appropriate
to the project.
After the work is done, a
report is issued to the re-
quester. Often these reports
go beyond the specific needs
of a particular site. Technical
information gained at
Superfund and RCRA sites
form the basis for a growing
background literature about
the specialized challenges of
complex environmental
matrices and also serve to
validate research developed
procedures, methods, and
ideas.
TECHNICAL FOCUS
The TSC provides support to
the Regions in site character-
ization technologies such as
field-portable X-ray fluores-
cence (FPXRF), soil-gas
measurement, geophysics,
special analytical services,
quality assurance, chemical
analysis, radiochemical
analysis, geostatistics,
statistical design, GIS, and
data interpretation.
specialized teams equipped
with portable or deployable
instruments to assist the
Regions with the screening
and site-characterization
work that forms the basis for
all subsequent work.
When on-site work is re-
quired, the TSC mobilizes
13194X9200C
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DOCUMENT
REVIEWS
In addition to the deployment
of field scientists, the TSC
helps the Regions evaluate
documents that have been
submitted by local contrac-
tors. This support is crucial
to wise decision-making by
the Regions. Team efforts
between the TSC and the
Region result in better
technology, quicker re-
sponse, and greater legal
defensibility.
PUBLICATIONS
The TSC manager is a
member of various technical
forums. This participation
often leads to the authorship
or coordination of issue
papers relating to the use of
innovative technologies for
monitoring and site charac-
terization.
Technical support projects
are documented in reports to
the Regions which vary in
length and complexity
according to the project
needs. Projects can identify
areas for further research or
develop protocols for experi-
mental or sampling design.
The TSC participates in
interagency workshops with
the U.S. DOE and U.S. DOD
and together these organiza-
tions have published guid-
ance documents that address
the special challenges of
heterogeneous wastes at
federal and other facilities.
Through the Technology
Transfer Project, the TSC
"markets" its services to the
Regions and beyond. Fact
Sheets describe dozens of
analytical and field technolo-
gies that are available
through the TSC. Other
technology transfer activities
include the production of
videos outlining various
EMSL-LV activities and the
publication of a bimonthly
newsletter, The EMSL-LV
Bulletin, that is distributed to
a growing mailing list of more
than 500 interested parties.
REFERENCES
Included here is a sampling of EMSL-LV TSC publications. For a copy of any of these, or for a
packet of EMSL-LV Fact Sheets, contact the manager of the TSC.
Characterizing Heterogeneous Hazardous Wastes: Methods and Recommendations. EPA/
600/R-92/033, (The proceeding of a workshop held at the EMSL-LV aM co-sponsored by the
U.S. DOE.)
Lewis, T.E., A.B. Crockett, R.L. Siegrist, and K. Zarrabi, "Soil Sampling and Analysis for
Volatile Organic Compounds". EPA/540/4-91/001, (A Ground-Water Issue Paper.)
Breckenridge, R. P., J. R. Williams, and J. F. Keck. "Characterizing Soils For Hazardous Waste
Site Assessments". EPA/540/4-91/003 (A Ground-Water Issue Paper.)
FOR FURTHER INFORMATION
If you have questions about the services available through the Technology Support Center at
EMSL-LV or wish to be added to the TSC mailing list, contact:
^ T ^
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Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed, Las Vegas.
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INTRODUCTION
5-v rz^~er:a. Mc :;r -g
Systems Laooratory
P O Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Soil-Gas
Measurement
¦—""r^*—'
-
The term "soil-gas" refers to
the atmosphere present in
soil pore spaces. Volatile
compounds introduced into
the subsurface can be
present in the gas phase or
more commonly, can un-
dergo a transition from a
liquid or soroed phase (pure
product, dissolved, or
adsorbed to soil) to become
part of the soil atmosphere.
Techniques for measuring
soil gases were developed
early in this century for
agricultural studies and for
petroleum exploration.
Within the last 5 years, soil-
gas measurement has
become an accepted environ-
mental site screening tool.
The technique is rapid, low
cost, and provides a high
yield of information when
carefully applied. Because it
is an indirect measure of
underlying contamination and
because of the potential for
false negative results, the
technique should be used
only for site screening and
not for confirmation.
The fate and transport of
contaminants and their
occurrence and detectability
in the soil gases are very
compound- and site-specific.
Soil-gas technology is most
effective in detecting com-
pounds having low molecular
weights, high vapor pres-
sures, and low aqueous
solubilities. These com-
pounds volatilize readily as a
result of their favorable gas/
liquid partition coefficients.
Once in the gas phase,
volatile compounds diffuse
vertically and horizontally
through the soil toward zones
of lower concentration.
Degradation processes (e.g.,
oxidation or reduction) can
eliminate or transform con-
taminants in the soil atmo-
sphere. The susceptibility of
a contaminant to degradation
is influenced by such factors
as soil moisture content pH,
redox potential, and the
presence of microorganisms
that can degrade the com-
pound. Other site-specific
characteristics affecting
results are: soil type, air-filled
porosity, depth to the source,
barriers to vapor transport,
and hydrogeology. Because
site-specific factors influence
contaminant concentrations
detected in the soil gases, a
quantitative correlation
between soil-gas concentra-
tions and underlying contami-
nation is difficult to general-
ize.
APPLICATIONS
Soil-gas surveys can be used
to:
• identify contaminants and
relative concentrations
• identify sources; indicate
extent of contamination
• monitor the progress of
cleanups
• guide placement of subse-
quent confirmatory samples
(soil borings, monitoring
wells)
• monitor at fixed vapor wells
(long-term monitoring)
• detect leaks through use of
tracer compounds
Typical primary sources
include surface spills, leaking
tanks, pipes, trenches, dry
wells, or landfills. Contami-
nants from such sources
frequently reach the water
table, causing the groundwa-
ter to become a source of
contamination to down-
gradient sites. The nature of
the source will influence the
vertical and horizontal disper-
sion of gas-phase contami-
nant vapors.
Contaminants detectable in
soil gases include many
common chlorinated solvents
and the lighter fractions of
petroleum products, sub-
stances that are widespread
environmental contaminants.
Of the 25 most commonly
encountered contaminants at
Superfund sites, 15 are
amenable to detection by soil-
gas sampling. Inorganic
contaminants that can be
detected by soil-gas sampling
include radon, mercury, and
hydrogen sulfide.
SELECTED COMPOUNDS DETECTABLE IN SOIL GASES
Aromatic hydrocarbons:
Benzenes, toluene, xylenes, naphthalene
Aliphatic hydrocarbons:
C, - Ct0 (e.g., methane, butane, pentane,
iso-octane cyclohexane)
Mixtures:
Gasoline, JP-4
Chlorinated hydrocarbons:
Chloromethanes (e.g., chloroform,
carbon tetrachloride); chloroethanes;
chloroethenes (e.g., vinyl chlonde, di-, tn-,
and perchloroethene)
Other:
CO,, CS2, H2S, NOx, radon, mercury
compounds
1607EX90
-------
THE TECHNIQUE
Soil-gas samples can be
collected by active or passive
methods. For active sam-
pling, a probe is driven into
the ground and soil gases are
pumped from the subsurface
into a sample container (e.g.,
evacuated canister, tube,
glass bulb, gas sample bag,
syringe) or through a sorbent
medium. For passive
sampling, a sampler contain-
ing a sorbent with an affinity
for the target analytes is
placed in the ground for a
period of time, and contami-
nants are collected by virtue
of diffusion and adsorption
processes. After exposure,
the passive sampler is
transported to a laboratory for
analysis. The most com-
monly used technique for
analyzing soil-gas samples is
gas chromatography (GC) in
combination with a detector
appropriate to the target
analytes. Analyses can be
done on- or off-site. Soil-gas
samples can also be
screened in the field using
organic vapor detectors,
which provide results ex-
pressed as total hydrocarbon
concentration relative to a
calibration standard.
The design of a soil-gas
survey depends on the data
required (e.g., identifying and
quantifying specific com-
pounds vs. measuring total
hydrocarbon concentration)
and the nature of the contami-
nation. A feasibility study is
recommended whenever
possible, particularly for sites
where little information is
available. Such a study can
be valuable in verifying the
effectiveness of the method at
the site, selecting the appro-
priate sampling and analytical
methods, choosing the best
sampling depth, and optimiz-
ing other operational details.
Because soil-gas surveying is
an intrusive technique,
precautions must be taken to
avoid buried utility lines,
tanks, or other objects.
DATA QUALITY
OBJECTIVES AND
QA/QC
SUMMARY
Because soil-gas results
provide an indirect measure
of primary contamination,
data quality objective (DQOs)
for soil-gas surveys and the
QA required need not be as
strict as those for confirmatory
sampling and analysis of soil
or ground water. However,
because most soil-gas survey
objectives require compari-
son of data among points to
determine patterns of relative
concentration, the investiga-
tor must be able to determine
whether differences in value
are real or merely due to poor
method precision. Consis-
tency in procedures is
essential, as are collection
and analysis of replicate and
blank samples and regular
checks of instrument calibra-
tion. Materials that come into
contact with samples should
be inert and easy to decon-
taminate.
Soil-gas measurement can
be an effective method for
determining the source and
extent of volatile contami-
nants in the subsurface.
Because of the many site-
and compound-specific
factors that can influence
results, soil-gas measure-
ment should be done only by
experienced field investiga-
tors. With proper QA and
judicious data interpretation,
this technique is a useful,
low-cost site screening tool.
SUMMARY OF ADVANTAGES AND LIMITATIONS
OF SOIL-GAS MEASUREMENT
Advantages
Rapid
Low cost
Real-time results
Minimal disturbance to site
Umttatfona
Indirect measurement
Interferences (false negatives are a problem)
Application limited to high volatility/low solubility
compounds
REFERENCE
Guidance Document for Soil-Gas Surveying, In preparation under EPA EMSL-LV Contract No.
68-03-3245 by C.L. Mayer, Lockheed Engineering and Sciences Company, Las Vegas, NV, in
press.
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SEPA
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P O Box 93478
Las Vegas NV 89193-347!
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Field-Portable
X-Ray
Fluorescence
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INTRODUCTION
THE SURVEY
Field-portable X-ray fluores-
cence (FPXRF) is a site-
screening procedure using a
small, portable instrument
(15-25 lbs, or 7-12 Kg) that
addresses the need for a
rapid turnaround, low-cost
method for the in situ analy-
sis of inorganic contaminants.
Traditional Contract Labora-
tory Program (CLP) methods
of analysis may take 20 - 45
days per site to complete and
the analysis would cost much
more than FPXRF. FPXRF
can measure inorganic
elements when used with the
proper radioisotope source
and the appropriate stan-
dards. FPXRF is capable of
simultaneous analysis of up
to six analytes per model.
More than one model can be
applied to each spectrum
obtained. This method is
useful at various levels of
analysis, with data quality
An FPXRF survey is a com-
bined effort of field scientists
and geostatisticians. Ideally,
it is a pre-survey aerial photo-
graphic evaluation of the site,
a screening on-site to collect
site-specific calibration stan-
dards, an off-site calibration
of the instrument, and a final
on-site visit for data collection
and quality control. Then
geostatistical interpretation is
done and a site screening re-
port is published.
dependent upon the exten-
siveness of the survey, the
type of standards used, and
the reinforcement of data by
other collaborator methods.
FPXRF can be used for
periodic monitoring as
remediation proceeds. The
following table includes the
elements that are on the
EPA's Inorganic Target
Analyte List, with asterisks
designating the ones quantifi-
able by FPXRF.
Typically a field survey is re-
quested by an EPA region.
RPM's can contact local con-
tractors with the equipment
and expertise to do an
FPXRF survey. When spe-
cial help is needed, the RPM
may contact the EMSL-LV for
expert advice. The team that
responds is equipped with an
FPXRF instrument and all of
the necessary supporting
equipment to adequately as-
sess the site. Using the cali-
bration curve that has been
The EMSL-LV has been
requested to analyse six of
these elements to date:
arsenic, chromium, copper,
iron, lead, and zinc. Though
detection limits are highly
matrix dependent and site
specific, the detection limits
for these elements have been
in the 100 - 500 mg/Kg
range. The instrument used
at the EMSL-LV is an X-MET
880.
generated from site-specific
standards, the X-ray re-
sponses of the routine
samples are regressed
against this curve and an ana-
lytical result is generated.
Geostatistics, an interpretive
method which allows for the
similarity between neighboring
samples, is used to optimize
the sampling design prior to
the survey. After the sampling,
geostatistics is used to ana-
lyze the data and to produce
concentration isopleth maps.
TABLE 1
INORGANIC TARGET ANALYTE LIST
Aluminum
* Calcium
Magnesium
* Silver
* Antimony
* Chromium
Manganese
Sodium
* Arsenic
* Cobalt
* Mercury
* Thallium
* Barium
* Copper
* Nickel
* Vanadium
Beryllium
* Iron
* Potassium
*Zinc
* Cadmium
* Lead
* Selenium
Cyanide
* Indicates FPXRF quantifiable analytes.
0022EX90
-------
INSTRUMENTATION
HOW A FIELD
SURVEY IS
CONDUCTED
COST
ADVANTAGES AND
LIMITATIONS
X-ray fluorescence is based
on the fact that atoms
fluoresce in a unique and
characteristic way. By
bombarding a sample with
energy, the instrument
causes an electronic instabil-
ity. As the instability "relaxes"
to a more stable energy level,
X-ray fluorescence is emitted.
The detector senses and
counts this spectrum of
radiation which is a "finger-
print" of the specific analyte
and, on this basis,' identifies
the atom. Quantitation is
done against a calibration
curve that was generated by
the analysis of site-specific
standards.
X-ray fluorescence has been
a standard laboratory method
for years and the recent
availability of portable
instruments now allows this
method to be taken into the
field for use at hazardous
waste sites.
To effectively use FPXRF,
the field scientist must ask a
few questions. What is the
objective of the survey? What
data are needed? What is
the most efficient sampling
scheme? What are the data
quality objectives?
A complete FPXRF analysis
is based on calibration of
standards that are specific to
the site. These standards
are collected on the initial
site-screening visit and are
analyzed by a complete CLP
procedure in order to cali-
brate the FPXRF instrument.
Numerous in situ measure-
ments are made on the
hazardous waste site. QA/
QC is integrated into the
program. The resulting data
are not only quantitative, but
of known quality.
The average cost of in situ
FPXRF surveys, based on a
limited number of surveys
performed by the EMSL-LV
team in 1989 has been
between $25,000 and
$35,000. This cost includes
labor, transportation, an
aerial photographic pre-
survey, analysis of about 15
site-specific standards per
analyte, the FPXRF survey
of up to 150 measurements
per day, and a final report. A
typical survey in 1989 took
about 3 days. The complete
procedure from pre-survey
through final report took
about 4-6 weeks.
Advantages
Low cost
Ease of operation - portable,
moves to any site
Rapid results - real time
(once site-specific standards are available)
Limitations
Complex data interpretation -
for geostatistical investigations
Matrix variability
type of soil influences results
Less sensitive than a complete CLP analysis
REFERENCE
Raab, G. A., R. E. Enwall, W. H. Cole, III, M. L. Faber, and L. A. Eccles, July 1990, X-Ray
Fluorescence Field Method for Screening of Inorganic Contaminants at Hazardous Waste
Sites. In: Hazardous Waste Measurements, M. Simmons, Ed., Lewis Publishers, Chelsea, Ml.
^T,°4/
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FOR FURTHER INFORMATION
For technical information about FPXRF, contact:
Mr. William H. Engelmann
U.S. Environmental Protection Agency
P.O. Box 93478, Las Vegas, NV 89193-3478
(702) 798-2664
FTS 545-2664
For Technology Support information, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
P.O. Box 93478, Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270 • FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
Mobile Mass
Spectrometry
c/EPA
INTRODUCTION
INSTRUMENTATION
tec states
Environmental P"otec::cn
Agency
TECHNOLOGY SUPPORT PROJECT
Gas chromatography/mass
spectrometry (GC/MS) is the
EPA recommended method
for the analysis of volatile and
semivolatile organic com-
pounds. This proven analyti-
cal technique identifies and
quantifies organic com-
pounds on the basis of
molecular weight, character-
istic fragmentation patterns,
and retention time. Until
recently, it was not feasible to
bring a GC/MS instrument to
a hazardous waste site
because of its size and
weight, the need for strict
The Bruker system (specifi-
cally the MEM) was consid-
ered the most advanced
instrument available for this
testing and was, therefore,
the only one evaluated.
When other instruments
become available, compari-
sons will be performed. The
Bruker MEM is ca. 22" x 28"
x 30" and weighs about 500
pounds. It can be mounted in
a four-wheel drive vehicle
and taken directly to the site.
This instrument is equipped
with built-in power, resistance
to shocks, and will operate
from -30°C to 50°C with no
external cooling or heating
requirements. The mass
spectrometer has a mass
range of 1 -400 Daltons which
minimizes power consump-
tion. It can operate for 6-8
hours on battery power, or
indefinitely using a generator
'3—e-ta' Ucr -c-.-g
Syster-s i_aocra;on/
P O. Box 93-178
Las Vegas NV 89193-3478
control of temperature and
humidity, and the effect of
vibration during transport.
With the growing demand for
field-portable instrumentation
in the environmental area,
rugged, smaller units have
been developed. Bruker
Instruments, Inc. has sup-
plied EMSL-LV with a com-
plete mobile mass spectrom-
etry system to test under the
Superfund Innovative Tech-
nology Evaluation (SITE)
program. The performance
of this system was recently
demonstrated at two
or conventional AC power.
An MS-DOS 386 based data
system can be used to
acquire, analyze, and archive
all GC/MS data. Sampling
accessories are available for
a wide range of monitoring
situations: a "sniffer" with a
3.5 m GC column is used for
continuous air monitoring or
the thermal desorption of
organics from a soil surface.
A temperature programmable
GC with a capillary column is
also available.
The Bruker MEM offers
several analysis modes and
sample introduction methods
which can be chosen based
on the data quality objectives
(DQO) of the site. Two
modes, "rapid screening" and
"characterization", were
tested in the SITE demon-
stration. The rapid screening
mode allows a quick analysis
Superfund sites in Region I.
The mobile mass spectrom-
eter was used for the analy-
sis of PCBs in soil at the Re-
Solve, Inc. Site and for PAHs
in soil and VOCs in ground-
water at the Westborough
Township Site. Because GC/
MS is the preferred method
for the analysis of volatile and
semivolatile organic com-
pounds, mobile GC/MS is
anticipated to become the
major technology for field
analysis of these contami-
nants in the 1990s.
for up to ten organic com-
pounds simultaneously. The
more accurate characteriza-
tion mode follows a CLP-type
protocol, including an extrac-
tion, 5-point calibration, and
data acceptance windows.
Once the sample is intro-
duced, it passes through a
semipermeable membrane
into the ionization source
where it is fragmented into
characteristic ions. These
ions are then accelerated,
focused, and detected. The
resulting mass spectrum is
compared against known
compounds in the computer's
library. The quantitation limits
of the MEM vary depending
on several factors including:
• analysis mode used
• analytes detected
• matrix analyzed
-------
SCOPE
The desirability of field-
portable GC/MS instrumenta-
tion is obvious. The MEM
provides the Agency with an
instrument for field analysis
that is capable of achieving a
wide range of DQOs. Be-
cause of the proven track
record of GC/MS, field GC/
MS is a superior choice to
other novel techniques which
have been proposed for field
analysis but lack a basis in
routine or special environ-
mental applications. By
replicating the method of
choice for organic analysis in
a unit that can be deployed to
hazardous waste sites, the
favored technology is moving
on-site. The on-site results
can be compared easily with
CLP results. Decisions can
be made at the site, based on
early results, to focus subse-
quent and intensive sampling
in areas of greatest contami-
nation. More than a field
screening tool, portable GC/
MS provides field scientists
with an instrument of ac-
cepted integrity and demon-
strated value. It allows field
scientists and on-scene
decision makers an opportu-
nity to compare field results
with historical databases.
The development and
implementation of these
instruments is of great
interest to environmental
scientists, especially those
working within the historical
framework of the CLP.
ADVANTAGES AND
LIMITATIONS
These newly tested field
methods are capable of
improving the overall reliabil-
ity of organic analysis in field
situations. As the technology
emerges, further break-
throughs in sensitivity, size,
and ruggedness will certainly
continue.
This is a system specifically
designed for field use flfli a
laboratory instrument taken
to the field.
Advantages
Simplified operations
Rapid turnaround
Unambiguous identification
Equivalent to EPA method
Limitations
Complex, requires trained personnel
Field quality control
High initial equipment cost
FUTURE PLANS
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Further testing of the Bruker
instrument and other
manufacturer's equipment is
planned. Evaluations of
these instruments and
comparisons between
laboratory and field analysis
data will address concerns
about volatile loss during
shipment from field to labora-
tory. More analytes on the
hazardous substances list
(HSL) will be quantified by
portable GC/MS. The use of
the system with its ancillary
"sniffer" for air testing will be
considered. Additional
automated sampling devices
will be developed and tested.
Computer software will be
modified to generate reports
in Agency format. Increased
demand for this instrumenta-
tion will guide research to
meet the growing needs of
environmental field scientists.
REFERENCES
Project and Quality Assurance Plan For Demonstration of the Bruker Mobile Mass Spectrom-
eter, U.S. EPA Report, September 1990.
Robbat, Jr., A., and G. Xyrafas. "Evaluation of Field Purge and Trap Gas Chromatography
Mass Spectrometry," presented at the First International Symposium; Field Screening Methods
for Hazardous Waste Site Investigations, Las Vegas, NV, October 1988, proceedings.
FOR FURTHER INFORMATION
For specific information on mobile mass
spectrometry, contact:
Dr. Stephen Billets, Jr.
Quality Assurance and Methods
Development Division
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas, Nevada 89193-3478
(702) 798-2232
FTS 545-2232
For further information on technology
support, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270/734-3207
FTS 545-2270
FAX/FTS 545-2637
-------
sepa
INTRODUCTION
METHODOLOGY
SCOPE
U"(isc Slates
Environmental Protection
•gency
environmental Mentoring
Systems LaDoratcry
P.O Box 93478
Las Vegas NV 89193-3478
Nov?
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Geophysics: A Key Step
in Site Characterization
Distance (feat)
A frequent problem facing en-
vironmental scientists working
on the remediation of hazard-
ous waste sites is locating
subsurface contamination and
delineating features that influ-
ence its movement. When a
site manager requires infor-
mation about subsurface char-
acteristics with as little subsur-
face disturbance as possible,
geophysics offers an array of
techniques. Focusing on the
location and assessing the
extent of contamination can
lead to a more clearly defined
view of the site that will save
time, money and provide a
better degree of safety.
Geophysicists at the Environ-
mental Monitoring Systems
Laboratory-Las Vegas
(EMSL-LV) are experienced
in using several geophysical
methods that can aid in the
detection and definition of
contamination. This informa-
tion can assist the site man-
ager with cost-effective, rea-
sonable options during site
characterization.
All geophysical techniques are
based on elements of physics
and geology. These methods
respond to the physical
properties of the subsurface to
infer the geological formations
and structure, and the pres-
ence, location, distribution and
size of buried objects.
Generally, the methods fall
into six categories:
• seismic (including reflection
and refraction)
• electrical methods (including
direct current resistivity and
electromagnetic
techniques)
• magnetic
• gravity
• radiometric
• ground-penetrating radar
Many of these measurements
can be made on the surface
of the ground, by airborne
methods, or in boreholes. By
observing some characteris-
tic of the measured signal,
the geophysicist is able to
estimate the size, shape,
depth, and other characteris-
tics of the subsurface objects.
Sophisticated computer
algorithms are available that
aid the geophysicist in making
these interpretations. These
usually require some degree
of experience and expertise
on the part of the geophysi-
cist. Because of ambiguity in
the interpretations, usually
more than one geophysical
method is applied at a site.
The equipment used in
making geophysical measure-
ments varies but field-
deployable units are available
in all categories.
Successful use of information
from geophysical measure-
ments for site characteriza-
tion depends on the
investigator's ability to
understand and interpret
data. Factors include:
1) the geologic and
hydrogeologic characteris-
tics of the contaminated
site.
2) physical property differ-
ences related to natural
geologic occurrences,
such as those at contacts
between different kinds of
rocks.
3) physical property changes
produced by contami-
nants, such as changes in
the electrical properties.
4) constraints that act within,
and on, a system, e.g., the
influence of large solution
cavities on ground-water
movement.
5) sources and characteris-
tics of noise that can
obscure the signal and
interfere with data inter-
pretation.
The thoughtful use of geo-
physics in environmental
science benefits the site
manager in several ways. It
provides a reliable 'baseline'
characterization of a newly
identified site. It helps
decision makers to target
future characterization and
remediation efforts in a
focused manner. It aids in
0331EX91
-------
SCOPE (Continued)
the ongoing monitoring of
remediation efforts.
When a site manager first
contacts a geophysicist,
several questions will arise.
Why suspect subsurface
contamination? How deep is
the buried object or plume? Is
historical data available about
the site? The Geophysics
Advisor Expert System was
developed to assist the non-
geophysicist managers in
evaluating what geophysical
techniques may be useful for
solving their site-specific
problems. It is designed to
assist their interactions with
the geophysicists. The
geophysicist may also ask for
a sample of soil or other
material from the area of
interest so that physical
property variations can be
evaluated. Once background
work has been completed
(searching for historical data,
obtaining topographic maps
and aerial photographic
images, inspecting any other
geophysical data that is
available), the geophysicist
will select the best experi-
mental design to characterize
problems at the site. In some
cases, a preliminary site visit
is made. On the basis of the
background information and
the preliminary site visit, the
best geophysical methods
are chosen and work begins.
Geophysical measurements
follow good experimental and
sampling design strategies to
ensure that the best technical
accomplishment is achieved.
Following the data gathering,
the geophysicist uses com-
puterized modeling algo-
rithms to interpret the data
that were generated at the
site. Thoughtful data interpre-
tation is fundamental to the
success of any geophysical
effort.
ADVANTAGES AND
LIMITATIONS
The use of geophysical
measurements to determine
the location and extent of
subsurface contamination is
an Agency-accepted method
for site characterization.
Geophysicists are highly
trained and experienced
scientists. As more geo-
physicists enter the environ-
mental workplace, it is
expected that the demand
for, and the use of, this
expertise will increase.
Advantages
Limitations
Surface geophysical
techniques provide a good
non-intrusive method for
characterization of subsur-
face features
Better safety consider-
ations due to the non-
intrusive aspect
Cost effective, some
methods can be used to
initially screen a large area.
Results require interpreta-
tion and can be non-unique
Some methods require
highly trained personnel
Direct confirmation of
results still required
REFERENCES
Introductory:
Benson, R. C., R. A. Glaccum, and M. R. Noel, Geophysical Techniques for Sensing Buried Waste and
Waste Migration, U.S. EPA Environmental Monitoring Systems Laboratory, Las Vegas.
Olhoeft, G., Geophysics Advisor Expert System, June 1989, EPA Project Report EPA/600/4-89/023.
Mora Advanced:
Telford, W. M., L P. Geldart, R. E. Sheriff, and D. A. Keys, Applied Geophysics, Cambridge University
Press, 1976.
FOR FURTHER IN FORM A TION
XG*I0/VV
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~
For more information about the geophysics
program at the EMSL-LV, contact:
Or. Aldo Mazzella
Advanced Monitoring Division
U.S. Environmental Protection Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2254
FTS 545-2254
For information about the Technology Support
Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
INTRODUCTION
'Jn.ieC 1ai G 3
Environmental Protection
Agency
5nv rcr~, = r:ii Mcm;orr,g
Systems Laocraton/
P O Box 93-73
Las Vegas NV 89193-3473
¦',3
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
SEPA ASSESS:
A Quality
Assessment
Program
An EMSL-IV
Environmental
Software
Program
ASSESS is an interactive
program designed to assist
the user in statistically
determining the quality of
data from soil samples taken
at a hazardous waste site.
EMSL-LV scientists have
developed this public-
domain, user-friendly Fortran
program to assess precision
and bias in the sampling of
soils. The total error in a
sampling regimen is the sum
of measurement variability
and natural variability of the
contamination. It is the field
scientist's challenge to
mitigate the measurement
variability by careful sample-
taking, thoughtful sampling
design, and the use of
recommended quality as-
sessment samples. The
greatest potential for error,
both random and bias, is in
the sampling step. Field
conditions, tool contamina-
tion, operator differences, all
can affect variability and bias
in a sample before it gets to
the analytical step.
The value of ASSESS is its
ability to detect and isolate
error at critical steps in the
sampling and measurement
function. Installation is
simple and is described in the
User's Guide referenced at
the end of this text.
FEATURES
ASSESS plots graphics
directly on the screen to give
the user a quick look at data
or results. All graphics can
be formatted to give hard
copy via pen plotters or other
graphics printers.
ASSESS checks for missing
data and for data input errors
of sufficient magnitude to fall
outside numeric parameters
that have been previously
set.
Reports and plots can be
incorporated into
WordPerfect.
SCREENS AND
MENUS
After an introduction screen,
ASSESS presents screens
and menus beginning with
the Data Quality Objectives
(DQO) Screen. The user
inputs known information
about the site and sampling
method and desired confi-
dence ranges.
Next, the user may choose
the Sampling Considerations
Screen. This screen allows
entry of further specifics
about the field sampling,
such as, number of samples
taken, number of batches
analyzed, cost, and batch
data.
The next screen is the
Historical Assessment
Screen that provides options
for entry of historical data that
may be critical to the interpre-
tation of this sampling.
A Quality Assessment Data
Screen follows that allows the
user to view and edit the
quality assessment data that
are called for in the parent
document, A Rationale for
the Assessment of Errors in
the Sampling of Soils,
referenced at the end of this
fact sheet. These quality
assessment samples are
fundamental to the
successful use of ASSESS.
They include samples that
will check for and evaluate
error in every sampling step.
At this point, it is possible to
produce scatter plots to
visually inspect the
contribution to the total error
that is made by any particular
quality assessment sample
with the confidence in the
error estimates being a
function of the number of
data.
The Transforms Screen
follows and it gives the user a
method for applying unary or
binary operations to the
entire data set. For example,
the field scientist or data
interpreter may wish to
truncate the data, view the
plot as a log or In function, or
perform a basic mathematical
operation on all data.
The Results Screen displays
variances for sample collec-
tion, batch dissimilarity, sub-
sampling error, and handling
differences. This screen also
shows the total measurement
20S8EX93
-------
SCREENS AND
MENUS (Continued)
e or A report of the results
and a list of historical infor-
mation and the quality
assessment data may be
saved to a file or printed.
ASSESS is based on the use
of field duplicates, splits, and
performance evaluation
samples that isolate and
assess variability throughout
the measurement process.
An option is provided for the
use of duplicates and spirts in
the calculation of variability
when inadequate types and
numbers of performance
evaluation samples exist.
DATA FILES
ASSESS incorporates simple
ASCII text files that can be
created with any text editor.
Two output files can be
produced by ASSESS, one of
which can be read as a data
file by ASSESS and the
other, which is not ASSESS
readable, gives a report-like
document. A third type is
provided so that the user may
edit an input file without
entering all the data through
ASSESS.
STATUS
ASSESS is currently avail-
able in Version 1.0. This is a
prototype environmental
software package. Further
development is planned and
input from field scientists and
EPA Regional personnel is
solicited so that the next
version may be more tailored
to user needs.
ASSESS is based on the
EPA publication, A Rationale
for the Assessment of Errors
in the Sampling of Soils, and
it is strongly recommended
that users familiarize them-
selves with the concepts in
that document before trying
to apply ASSESS.
HARDWARE
REQUIREMENTS
Hardware requirements for using ASSESS are:
• IBM PC (or compatible)
• 1.2 MB floppy disk drive 5 1/4" (or 3 1/2" DD or HD)
• Minimum graphics hardware is Hercules graphics card, monochrome display with graphics
capabilities, CGA and EGA
• Minimum 512 K RAM
• Math coprocessor chip is recommended but not required
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REFERENCES
ASSESS User's Guide, U.S. EPA Report, EMSL-LV, in press.
van Ee, J. J., L. J. Blume, and T. H. Starks, A Rationale for the Assessment of Errors in the
Sampling of Soils, EPA Report, EPA/600/4-90/013, May 1990.
FOR FURTHER INFORMA TION
For copies of the ASSESS program, refer
to NTIS Order Number PB93-505295,
and contact:
United States Department of Commerce
Technology Administration
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
(703) 321-8547 (FAX)
Telex: 64617
For general questions regarding the use of
ASSESS at a site, contact:
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270/734-3207
(702) 798-3146 (FAX)
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
OT'iec a;ates
rr:vircnmenial Prc:ec::cn
Agency
z"viror~er;ai Mcrxorrg
Systems LaDorator/
P 0 Box 93478
Las Vegas NV 89193-347!
OFFICE OF RESEARCH AND DEVELOPMENT
Hypertext: A
Showcase for
Environmental
Documents
f/EPA
INTRODUCTION
The amount of "required
reading" for those engaged in
hazardous waste site
remediation is overwhelming.
Documents pile up - often
leaving the scientist no option
but to briefly review the
abstract or the executive
summary. Fortunately, there
exists a computer software
tool, hypertext, that allows for
documentation on disk that
can provide all readers/users
with various layers of infor-
mation. The tiered knowl-
edge in hypertext makes it
ideal for experts in the field of
the publication who can scan
through the general informa-
tion and concentrate on a
particular section. It is also
suited to the novice in the
document's area who can
access highlighted areas for
in-depth definitions of unfa-
miliar terms, fuil-screen
presentations of tables and
figures, and references to
ancillary works.
Hypertext is an easy-to-use,
timesaving reading tool for
the overburdened scientist.
The ability to read an elec-
tronic book helps each reader
optimize the information-time
ratio.
Scientists at the EMSL-LV
have used hypertext on a
frequently used document, "A
Rationale for the Assessment
of Errors in the Sampling of
Soils" by J. Jeffrey van Ee,
Louis J. Blume, and
Thomas H. Starks. The
TECHNOLOGY SUPPORT PROJECT
original hardcopy document
is about 60 pages long, and
contains 4 figures and 8
tables. The document also
contains several formulas
that may be unfamiliar to
many users. The hypertext
version fits on a floppy disk,
keeps general information
"hidden" unless it's requested
by a novice user, and high-
lights frequently used tables
for easy access.
Hypertext can be applied to
any document that exists in
digital form. The level of
hypertext a document needs
depends on the complexity
and length of the original
document and the anticipated
expertise of the reading
audience.
THE RATIONALE
DOCUMENT
The Rationale mentioned
above addresses the com-
plexity of the sampling and
analysis of soils for inorganic
contaminants from experi-
mental design to the final
evaluation of all generated
data. Sources of error
abound but they can be
successfully mitigated by
careful planning or isolated
by intelligent error assess-
ment. Error can be either
biased or random. Biased
error is indicative of a sys-
tematic problem that can
exist in any sector of soils
analysis, from sampling to
data analysis. The first step
in analysis of variability is to
establish a plan that will
identify errors, trace them to
the step in which they
occurred, and account for
variabilities to allow direct
corrective action to eliminate
them.
Error assessment should be
understood by the field
scientist and the analyst. To
implement the ideas in the
Rationale document and aid
scientists in the estimation
and evaluation of variability,
the EMSL-LV has developed
a computer program called
ASSESS. By applying
statistical formulas to quality
assurance data entered,
ASSESS can trace errors to
their sources and help
scientists plan future studies
that avoid the pitfalls of the
past.
HOW HYPERTEXT
WORKS
Scientists at the EMSL-LV
took the disk containing the
Rationale document and
extracted sections such as
the Table of Contents, tables,
figures, and certain equations
and formulas. These sec-
tions appear separately when
selected in the new hypertext
version. Then, throughout
the document, certain words
and phrases were highlighted
so definitions can be ac-
cessed by a keystroke.
When a reader receives a
hypertext document on disk,
he or she can look at the
Table of Contents and decide
which sections to read. By
selecting, for example, the
section entitled "background",
02S5EX91
-------
HOW HYPERTEXT
WORKS (Continued)
the reader can be briefed on
the scope of the document.
A term within the Background
section, e.g., "representative"
may be highlighted. Readers
wishing the definition of
"representative" as used in
this document may get an
immediate clarification. In
traditional (linear) hardcopy
documents, a reader must
either wait for the definition to
be clarified in text or seek an
external definition through
outside reference materials.
BRIDGE TO ASSESS
The Rationale document is
the basis for an EMSL-LV
environmental software
program called ASSESS.
The philosophy and statistical
background in the document
is exercised practically with
ASSESS, which is also
available on disk. The
hypertext version of the
Rationale document prepares
the reader to use ASSESS
and also serves as a physical
link to the program. The last
item on the Rationale docu-
ment hypertext menu is
"ASSESS". After becoming
familiar with the concepts in
the document, the user may
select "ASSESS" to begin to
use the software.
This hypertext linkage of two
or more documents or
programs can simplify and
clarify many software applica-
tions for novice users. By
providing ASSESS users with
the technical background in
its development and Ratio-
nale document readers with a
viable program, hypertext
serves all levels of users in
error-tracing in the complex
application of soil sampling.
ADVANTAGES AND
LIMITATIONS
Increased availability of
computer workstations and
the development of user-
friendly programs have made
hypertext an almost unquali-
fied bonus to busy readers/
users. Hypertext is easily
and effectively used for:
acronyms and abbreviations,
terms and phrases, tables
and figures, graphics, formu-
las and references.
Advantages
Limitations
• Streamlined and non-
• Availability of computer
interruptive
with appropriate hardware
• Linkage to other hypertext
• Some computer literacy
documents
required
• Time-saving for expert;
instructional for novice
HARDWARE
REQUIREMENTS
Hardware requirements for
using this hypertext package
are:
• IBM PC (or compatible)
1.2 MB floppy disk drive,
5 1/4" (or 3 1/2" DD or HD)
Minimum graphics hard-
ware card, monochrome
display with graphics
capabilities, VGA and EGA
Minimum 640 K RAM
Math coprocessor chip is
recommended but not
required
REFERENCES
Text, ConText, and HyperText; Writing with and for the Computer, E. Barrett, ed., The MIT
Press, 1988.
van Ee, J. J., L. J. Blume, and T. H. Starks, A Rationale for the Assessment of Errors in the
Sampling of Soils, EPA Report, EPA/600/4-90/013, May 1990.
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FOR FURTHER INFORMATION
For more details on Hypertext and the
Rationale document, contact:
Mr. J. Jeffrey van Ee
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2367
For information about the Technology Support
Center at EMSL-L V, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gertach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
SEPA
Envircnrner'.ai Prc;sc.;cn
Agency
Systems Laocratcry
P O. Box 93473
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Scout: A Data
Analysis Program
TECHNOLOGY SUPPORT PROJECT
AnEMSL-LV
Environmental
Software
Program
INTRODUCTION
The complexities of correct
data interpretation challenge
environmental scientists
everywhere. Environmental
software packages have
been developed to address
the various needs of data
analysts and decision mak-
ers. One frequent need is for
the reliable determination of
outliers in a data set. Scout
is a program developed to
identify multivariate or
univariate outliers, to test
variables for lack of normal-
ity, to graph raw data and
principal component scores,
and to provide output of the
results of principal compo-
nent analysis. Scout pro-
vides interactive graphics in
two and three dimensions.
There are many advantages
of a graphical display of data
in a multidimensional format:
it allows a quick visual
inspection of data, it accentu-
ates obvious outliers, and it
provides an easy means of
comparing one data set with
another. Scout has the
flexibility to allow viewing and
limited editing of a data set.
Scout features on-line help,
with a "built-in" users guide.
Scout is a valuable addition
to the library of environmental
software packages available
from the EMSL-LV.
FEATURES/
SPECIFICATIONS
Scout is a public domain,
Turbo Pascal program that is
user friendly and menu
driven. Scout reads ASCII
data files that are in Geo-
EAS format. The first line of
a Geo-EAS data file is a
comment line, generally used
to describe the origin of the
data. The second line of the
file must contain the number
of variables - always a
number greater than or equal
to 1 and less than or equal to
48. The next lines contain
variable names in the first 10
columns and the associated
values in the next 10 col-
umns. Scout is compatible
with most IBM personal
computers that have an EGA,
VGA, or Hercules graphics
system. Scout will run with or
without a math co-processor,
but this feature is preferred
for handling floating point
calculations. A fixed disk
drive is strongly recom-
mended because Scout
performs many transfers
between memory and disk
during execution. On-line
help is available throughout
Scout and the user can
access it by selecting the
"System" option in the main
menu and then selecting
"Information".
MENUS
There are five menus in
Scout: file management,
data management, outliers,
principal components analy-
sis, and graphics.
After the introduction screen,
the user should choose the
"File Management" option on
the main menu. This option
allows the user to load the
Scout data file or read an
ASCII data file and to access
various subdirectories of
data. Scout saves data files
in two formats: binary and
the Geo-EAS ASCII format.
Scout has the ability to
search for file names, includ-
ing wild cards. The current
search string is printed at the
top of the window. Other
options in this area include
"Write ASCII Data File" for
saving the Scout file and
"Merge Two Data Files" for
combining two files into one.
The second menu is "Data
Management" which includes
options for editing data,
variables, and observations.
This menu also displays
summary statistics, such as
mean, standard deviation,
and variance. Additionally,
there is a Transform" option
which allows the user to test
each variable for lack of
normality, based on the
Kolmogorov-Smirnov test at
the five percent significance
level. The critical value, test
statistic, and apparent
conclusion are displayed.
The Anderson-Darling test is
also performed and a hori-
zontal histogram is displayed
at the bottom ol the screen.
Menu three is "Outliers",
which applies two powerful
tests for discordancy to the
data: the (Mahalanobis')
generalized distance, and the
(Continued)
2057EX93
-------
Mardia's multivariate kurtosis
test. After selecting "Outli-
ers", the user can tell Scout
which variables to test, or use
the default wherein Scout
tests all variables. The user
must then decide to use the
generalized distance test or
Mardia's kurtosis. If a large
proportion of the data is
identified as discordant, the
user should be cautious that
the problem may be due to
lack of multinormality. The
outlier report may be dis-
played, sent to a file, or
printed. By selecting "Causal
Variables" the user can test
each variable for its contribu-
tion to the discordant nature
of the outlier. This option can
trace some independent
errors, such as typographical
or transcription errors.
The fourth menu is "Principal
Component Analysis" which
allows the user to select the
variables to be used and to
display covariance or correla-
tion. By choosing'the "View
Components" option, the user
can view the eigenvectors
and eigenvalues of the PCA.
Scout will prompt the user to
specify whether or not to
include previously deter-
mined outliers. The user can
graph the component scores,
which are products of the
eigenvectors and the stan-
dardized observation vectors.
A "Transform Data" option is
available to change the data
in memory from observations
to component scores.
The fifth, and final, menu is
"Graphics" which features
two graphics systems: two-
dimensional and three-
dimensional. The two-
dimensional system is used
to display scatter plots and
x-y plots. The three-dimen-
sional system is used to
display three variable plots,
which can be rotated to
illustrate the added dimen-
sion. The user can modify
graph colors and shapes.
Graphics screens may be
saved by writing to a file on
disk. The user can change
the size of the graph by
zooming in or out using the
"+" orkeys. The four
arrow keys are used to rotate
the graph. The left and right
arrows rotate the graph
around the Z axis. The up
and down arrows rotate the
graph around an imaginary
horizontal axis that passes
through the origin. Another
feature, "Search Observation
Mode", is available and
allows users to identify the
individual observations
shown on the graph.
REFERENCES
Chemometrics: A Textbook. Massart, D. L., B. G. M. Vandeginste, S. N. Deming, Y. Michotte,
and L. Kaufman, Volume 2 in the Series "Data Handling in Science and Technology",
B. G. M. Vandeginste and L. Kaufman, eds., Elsevier, Amsterdam, the Netherlands, 1988.
Gamer, F. C., M. A. Stapanian, and K. E. Fitzgerald, Finding Causes of Outliers in Multivariate
Data, J. Chemometrics, in press.
FOR FURTHER INFORMATION
For copies of the Scout program, refer to NTIS Order Number PB93-505303, and contact:
United States Department of Commerce (703) 487-4650
Technology Administration (703) 321-8547 (FAX)
National Technical Information Service Telex: 64617
5285 Port Royal Road
Springfield, VA 22161
For additional technical information about
Scout, contact:
Dr. George Flatman
U.S. Environmental Protection Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2628, FTS 545-2628
For information about the EMSL-LV
Technology Support Center, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratc
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270, (702) 798-3146 (FAX)
The Technology Support Center fact sheet series is developed and written by
Clare L. Geriach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
c/EPA
INTRODUCTION
-^vironmeniai Proteoon Sysiems Laooraicry
Agency ? O 3ox 53478
Las Vegas NV 39193-3^78
OFFICE OF RESEARCH AND DEVELOPMENT TECHN(
Geo-EAS: Software
for Geostatistics
The Environmental Monitoring
Systems Laboratory-Las
Vegas (EMSL-LV) can meet
the needs of scientists who
work with spatially distributed
data. The complexity of
contaminant distribution and
migration at hazardous waste
sites requires a mathematical
method that is capable of
interpreting raw data and
converting them to useful
information. Geostatistics
began in the mining industry
and has grown to include
applications ranging from
microbiology to air monitoring.
Though the application of
geostatistics is crucial to the
delineation of buried contami-
nants, not every field scientist
can be expected to develop
customized geostatistical
SUPPORT PROJECT
algorithms for individual sites.
Geostaticians at the EMSL-
LV developed a software
package, Geo-EAS in 1988.
The current version, Geo-EAS
1.2.1, was released in 1990.
This program offers the
environmental scientist an
interactive tool for performing
two-dimensional geostatistical
analyses of spatially distrib-
uted data.
THE METHODOLOGY
Geostatistical methods are
useful for site assessment
and monitoring where data
are collected on a spatial
network of sampling loca-
tions. Examples of environ-
mental applications include
lead and cadmium concentra-
tions in soils surrounding
smelters, and sulfate deposi-
tion in rainfall. Kriging is a
weighted moving average
method used to interpolate
values from a data set onto a
contouring grid. The kriging
weights are computed from a
variogram, which measures
the correlation among sample
values as a function of the
distance and direction be-
tween samples.
advantages over other inter-
polation methods:
Smoothing
Kriging regresses estimates
based on the proportion of
total sample variance ac-
counted for by random noise.
The noisier the data set, the
less representative the
samples and the more they
are smoothed.
Declustering
The kriging weight assigned
to a sample is lowered to the
degree that its information is
duplicated by highly corre-
lated samples. This helps
mitigate the impact of
oversampling hot spots.
Anisotropy
When samples are highly
correlated in one direction,
kriging weights will be greater
for samples in that direction.
Precision
Given a variogram represen-
tative of the area to be esti-
mated, kriging will compute
the most precise estimates
from the data.
Estimation of the variogram
from sample data is a critical
part of a geostatistical study.
Geo-EAS is designed to
make it easy for the novice to
use geostatistical methods
and to learn by doing. It also
provides sufficient power and
flexibility for the experienced
user to solve practical
problems.
Kriging has a number of
EQUIPMENT
REQUIREMENTS
Geo-EAS was designed to
run under DOS on an IBM,
PC, XT, AT, PS2, or compat-
ible computer. Graphics sup-
port is provided for Hercules,
CGA, and EGA. At least 512
Kb of RAM is required, but
640 Kb is recommended. An
arithmetic co-processor chip
is strongly recommended due
to the computationally inten-
sive nature of the programs,
but is not required. Programs
may be run from floppy disk
but a fixed disk is required to
use the programs from the
system menu. The system
storage requirement is ap-
proximately three megabytes.
For hardcopy, a graphic
printer is required. Support is
provided for most plotters.
Design features such as
simple ASCII file formats and
standardized menu screens,
give Geo-EAS flexibility for
future expansion. It is antici-
pated that Geo-EAS will be-
come a significant technology
transfer mechanism for more
advanced methods resulting
from the EMSL-LV research
and development programs.
Geo-EAS software and docu-
mentation are public domain,
and may be copied and dis-
tributed freely.
2060EX930DC
-------
MAPS AND MENUS
The Geo-EAS programs use
an ASCII file structure for
input. The files contain a
header record, the number of
variables, a list of variable
names and units, and a nu-
meric data table.
All Geo-EAS programs are
controlled interactively
through menu screens which
permit the user to select op-
tions and enter control pa-
rameters. The programs are
structured to avoid a "black
box" approach to data analy-
sis. Several of the more
complex programs permit the
user to save and read param-
eter files, making it easy to
rerun a program.
The programs DATAPREP
and TRANS provide capabil-
ity for manipulating Geo-EAS
files. Files can be appended
or merged, and variables can
be created, transformed, or
deleted. Transformation
operations include natural
log, square root, rank order,
indicator, and arithmetic
operations.
POSTPLOT creates a map of
a data variable in a Geo-EAS
data file. Symbols represent-
ing the quartiles of the data
values or the values them-
selves are plotted at the
sample locations.
STAT1 computes univariate
statistics, such as mean and
standard deviation, for vari-
ables in a Geo-EAS data file,
and creates histograms and
probability plots.
SCATTER and XYGRAPH
both create x-y plots with
optional linear regression for
any two variables in a Geo-
EAS file. SCATTER is useful
for quick exploratory data
analysis, while XYGRAPH
provides additional capabili-
ties such as multiple "y" vari-
ables, and scaling options.
PREVAR creates an interme-
diate binary file of data pairs
for use in VARIO, which com-
putes and displays plots of
variograms for specified dis-
tance and directional limits.
Variogram models can be
interactively fitted to the ex-
perimental points. The fitted
model may be the sum of up
to five independent compo-
nents, which can be any com-
bination of nugget, linear,
spherical, exponential, or
Gaussian models. XVALID is
a cross-validation program
which can test a variogram
model by estimating values at
sampled locations from sur-
rounding data and comparing
the estimates with known
values.
KRIGE provides kriged esti-
mates for a two-dimensional
grid of points. A shaded map
of estimated values is dis-
played and a Geo-EAS file of
kriged grid results is gener-
ated.
CONREC generates contour
maps from a gridded Geo-
EAS data file, usually the
output from KRIGE. Options
are provided for contour inter-
vals and labels and degree of
contour line smoothing.
REFERENCE:
Isaaks, E. H. and R. M. Srivastava, An Introduction to Applied Geostatistics, Oxford University
Press, New York, 1989.
AVAILABILITY-.
FOR FURTHER INFORMATION:
V0^'°A/V
T %
^ I echnology "Z-
° O * z
o >ypport o
%
roject
For copies of Geo-EAS, refer to NTIS Order
Number PB93-504967, and contact:
United States Department of Commerce
Technology Administration
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
(703) 487-4650
(703) 321-8547 (FAX)
Telex: 54617
For information about the Technology
Support Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory-Las Vegas
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
(702) 798-3148 (FAX)
The Technology Support Center fact sheet series is developed and written by
Clare L Geriach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
f/EPA
'jn,:=c i'a:ss
Environmental Protect.cn
Agency
Environmental Mcmtcrrg
Systems Laooratcry
P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Geophysics
Advisor
Expert System
j'-y ¦=;:
TECHNOLOGY SUPPORT PROJECT
An EMSL-LV
Environmental
Software
Program
INTRODUCTION
The Environmental Monitor-
ing Systems Laboratory - Las
Vegas (EMSL-LV) is con-
cerned with the selection of
correct monitoring methods.
Sometimes the best tech-
nique is not easily discern-
ible. This is particularly a
problem in sampling and
monitoring complex matrices,
like soil and sediment, and
when buried structures and
plumes are hidden from sight.
The characterization and
remediation of a hazardous
waste site involves several
disciplines, from experimental
design to analytical protocol.
Individuals who decide upon
methods and who are
responsible for approving
contractor suggestions need
an easy-to-use text or
computer program that will
guide them in expensive and
decisive actions.
The decision to use geo-
physical methods and which
geophysical method to use is
a challenge to site managers.
The EMSL-LV, in cooperation
with the U.S. Geological
Survey, has developed an
expert system, Geophysics
Advisor, to aid these person-
nel in critical decisions about
geophysical methods that
may impact the quality and
reliability of their data. This
program is built on a founda-
tion of expertise in applying
geophysical methods to
complex hazardous waste
sites. The current version,
Geophysics Advisor 1.0, is
designed to meet the needs
of non-geophysicists to assist
and educate them in their
interaction with geophysi-
cists. It is not intended to
replace the expert advice of
competent geophysicists.
THE PROGRAM
Geophysics Advisor 1.0 asks
questions about the site,
cultural noise, and the
contamination problem. The
program builds upon the
user's answers to early
questions and poses subse-
quent questions on this basis.
At the end of the run, the
program will indicate any
inconsistencies in the user's
responses. The user may
then return to specific ques-
tions and consider changing
the answer.
The program considers
several geophysical methods:
• electromagnetic induction
• resistivity
• ground-penetrating radar
• magnetic
• seismic
• soil gas
• gravity
• radiometric
Geophysics Advisor recom-
mends the type or types of
geophysics that will most
likely fit the site requirements
for determining the location
of contamination and provid-
ing site characterization.
The program will also tell the
user if the use of geophysics
is not suitable for the site. A
relative numerical ranking of
the various methods is
shown on screen, indicating
the degree of superiority of
one method over another.
Methods are also catego-
rized as "recommended,"
"not recommended," or
"uncertain of effectiveness."
Additionally, Geophysics
Advisor tells the user why the
various methods will
or will not work at the site.
Geophysics Advisor allows
the user to make soft re-
sponses such as "maybe"
and "don't know" so novice
(Continued)
2059BX93
-------
THE PROGRAM
(Continued)
users or those lacking
specific knowledge about the
site can access some of the
power of the program The
user will be asked about soil
type, cultural noise, contami-
nant identity and level, the
presence of underground
tanks or drums, and the
distance between various
buried items.
If a site is extremely complex,
it is recommended that the
user divide the site into
several subsite problems
The program can be run for
each subsite.
AVAILABILITY
Geophysics Advisor is a
public domain program
written to run on any IBM-PC-
DOS compatible computer. It
is written in True Basic and
requires 512 K memory when
the operating system is
included.
Geophysics Advisor is
available to all Agency users,
free of charge, upon receipt
of a pre-formatted 3 1/2" or
5 1/4" floppy disk. For copies
of Geophysics Advisor, or for
consultation with an EMSL-
LV geophysicist, contact:
Dr. Aldo Mazella
U.S. EPA
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2254
(FTS) 545-2254
REFERENCES
Introductory:
Benson, R. C., R. A. Glaccum, and M. R. Noel, Environmental Monitoring Systems Laboratory,
Las Vegas, 1982. Geophysical Techniques for Sensing Buried Wastes and Waste Migration,
U.S. EPA.
More Advanced:
Telford, W. M., L. P. Geldart, R. E. Sheriff, and D. A. Keys, Applied Geophysics, Cambridge
University Press, 1976.
User's Guide:
Olhoeft, G., Geophysics Advisor Expert System, EPA Project Report EPA/600/4-89/023,1989.
FOR FURTHER INFORMATION
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For information about the Technology
Support Center at the EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
(702) 798-3148 (FAX)
For copies of Geophysics Advisor
Expert System, refer to NTIS
Order Number PB93-505162
and contact:
United States Department of Commerce
Technology Administration
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
(703) 321-8547 (FAX)
Telex: 64617
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
vvEPA
'j^iice ^iates
Environmental Protection
Agency
rnvircr.~er:a' Mcri'crrg
Systems LaDoratory
P.O Box 93473
Las Vegas NV 39193-3478
Juv
OFFICE OF RESEARCH AND DEVELOPMENT
CADRE: A Data
Validation Program
TECHNOLOGY SUPPORT PROJECT
INTRODUCTION
The Environmental Monitor-
ing Systems Laboratory - Las
Vegas (EMSL-LV) has
developed a computer
software system to aid
environmental scientists and
data analysts in the evalua-
tion of data generated by the
Contract Laboratory Program
(CLP). This system, CADRE
(Computer-Aided Data
Review and Evaluation)
assists in the validation of
results from various CLP
methods.
CADRE provides data
analysts with a quick and
reliable method for examining
data that will be used for
decision making at hazard-
ous waste sites. The pro-
gram automates the phases
of data validation that involve
electronic-format data. The
data validation process
involves comparison of
quality control (QC) indicators
used in the analysis with pre-
established data quality
criteria. Non-compliant data
are qualified with appropriate
codes to indicate the seventy
of the defect. The final
assessment of the data is
made by the data reviewer,
using the information pro-
vided by CADRE.
Examples of QC parameters
that are checked by CADRE
are: holding time, blanks,
calibration, and precision.
FEATURES
CADRE can read data in
several CLP electronic
formats. It checks for data
completeness, and allow the
user to edit data. After the
validation is complete,
CADRE reports the results.
CADRE can be customized by
the user to validate data
collected using several
methods in the CLP. Users
can configure CADRE to
examine different compounds,
alternate quantitation limits, or
varying QC parameters.
Another customization of
CADRE involves changing
data validation criteria to
meet the needs of a modified
method. The user can
choose, for example, to allow
a longer holding time if the
compound of interest is
unlikely to volatilize or
degrade. The ability to
modify CADRE'S specific
data quality codes provides
the user with greater flexibility
and responsibility.
To protect the data from
tampering and from human
error, a layered security
system allows each user
access to the program
features he or she needs.
The program blends ease of
use with a sophisticated
screen system. Knowledge of
data validation rationale and
microcomputer operation are
recommended for the effec-
tive use of CADRE. A user's
guide, training courses, and
technical user support are
available from the EMSL-LV.
CLP ORGANIC
VERSION
The CLP ORGANIC version
of CADRE evaluates data
from CLP analysis of volatile,
semivolatile, and pesticide
compounds. Volatile and
semivolatile organic com-
pounds are analyzed by gas
chromatography/ mass
spectrometry (GC/MS).
Pesticide analysis is a GC
method.
CLP ORGANIC CADRE can
be customized to evaluate
modified versions of these
routine analyses. It can use
alternate data validation
criteria selected by the user.
Data can be read by CLP
ORGANIC CADRE from the
CLP Analytical Results
Database (CARD) or from
Agency standard format files.
Checks performed by
CADRE include:
quantitation limits
holding time
GC/MS tuning
calibration
internal standards
system performance
surrogate recovery
matrix spike recovery
precision of duplicates
contamination of blanks
0882EX91
-------
QUICK
TURNAROUND
METHOD VERSION
The Quick Turnaround
Method (QTM) version of
CADRE reviews data ob-
tained by the QTM methods.
There are QTM methods
available for VOC, PAH,
phenols, pesticides, and
PCB. These methods are
based on the need for fast
extraction and chromato-
graphic analysis within
2 days. For speed and
simplicity, QTM CADRE
works in conjunction with
other software for electronic
data transmission from the
laboratory to the user through
the Agency communications
network.
QTM CADRE is completely
automated. The data re-
viewer needs only to set up
the system and interpret the
reports.
ADVANTAGES AND
LIMITATIONS
HARDWARE
REQUIREMENTS
The use of computerized
data evaluation is changing
the workplace for many data
reviewers. The automation of
routine checks will give the
individual more time to
thoughtfully interpret the
results.
It is anticipated that in-
creased accessibility of
computer hardware to
personnel will lead to greater
demand for programs like
CADRE that will streamline
routine work. Currently,
CADRE is being developed
for inorganic methods.
Advantages
Limitations
Fast, complete, and
consistent data validation
Easy customization for
modified methods
Reduction of human error
Automated report
generation
Requires availability of
powerful computer for
efficient use
Reviewer judgement
needed for some decisions
Available for CLP organic
and QTM methods only
Needs complete data set in
electronic format
Hardware requirements for
using CADRE are:
• IBM PC (or compatible)
• MS-DOS (or equivalent)
• Hard disk drive
• 640 K RAM
A math coprocessor chip is
recommended but not
required. For easy use, a
mouse pointer is
recommended.
REFERENCE
Simon, A. W., J. A. Borsack, S. A. Paulson, B. A. Deason, and R. A. Olivero, Computer-Aided
Data Review and Evaluation: CADRE CLP Organic User's Guide, U.S. EPA, June 1991.
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FOR FURTHER INFORMATION
For further information on CADRE,
contact:
Mr. Gary Robertson
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2215, FTS 545-2215
For information about the Technology Support
Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270, FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
v>EPA
Unitea Slates
Environmental Protection
Agency
Environmental Monitoring
Systems LaDoratory
P O Box 93478
Las Vegas NIV 89193-3473
Octcoer ' 993
TECHNOLOGY SUPPORT PROJECT
ARC/INFO
Concepts
and
Terminology
-ar^tr
'Z-ter yjar
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2081GR9300C FS
Introduction
The U.S. EPA uses geo-
graphic information systems
(GIS) technology to obtain
reliable spatial information
from layers of descriptive
data. GIS provides methods
for the management, display,
manipulation, and analysis of
geographic data, such as
topological information,
transportation routes, geopo-
litical boundaries, and
waterways.
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) is the
EPA's center for research
and development for GIS
technology. As such, it
demonstrates the applicabil-
ity of GIS to various environ-
mental scenanos, including
Superfund and RCRA site
characterization and the
Environmental Monitoring
and Assessment Program
(EMAP).
Currently, the EPA uses
ARC/INFO, a full-featured
GIS software that follows a
geographic toolbox ap-
proach. There are distinct
tools for modeling and
feature manipulation for each
type of geo-dataset. Some
tools operate on entire
databases, others on entire
geo-datasets, and others on
individual features (1).
The Architecture
Map library tools define and
manage entire GIS data-
bases centrally. These
tools control the access,
modification, and update of
each theme within a map
library. Geo-dataset tools
operate on entire datasets
and can be categorized as
translation, edit, analysis,
and query/display tools.
Digital dataset conversion
into an ARC/INFO geo-
dataset is handled by a
large set of translation tools.
Digitize/edit tools support
creation of new geo-
datasets including topology,
locationai data, attribute
entry, and data verification.
Analysis tools perform
spatial analysis functions on
one or more datasets.
Examples of these analysis
tools are:
• Coverage overlay
• Theissen polygon
generation
• Surface and contour
generation
• Buffer zone generation
• Network allocation
• Map projection and
coordinate transformation
• Rubber sheeting
• Feature generalization
• Feature selection and
aggregation
• Arithmetic and logical at-
tribute combination
• Proximity and dispersion
analysis
The query/display tools
scale and position map data,
associate cartographic
symbols to map features,
and display, identify, and
control map features based
on their attributes. Feature-
level tools operate on
individual features within a
coverage.
ARC/INFO is structured so
that similar types of tools
are organized within soft-
ware modules that perform
similar sets of functions.
Table 1 lists the main
functions of each subsystem
of ARC/INFO.
ARC/INFO has an embed-
ded language processor that
is machine independent,
providing a consistent way
to control the user environ-
ment, command processing,
and application develop-
ment.
20Slo33odc
-------
Module Name
Table 1. ARC/INFO Subsystems
Main Function
Geographic
Concepts in GIS
Start other modules, data conversion, analysis and manipulation, coordinate
transformation, topology generation, attribute automation, database
construction, plotting, coverage and workspace management
Vector and raster data display and query. Spatial analysis
Vector data editing and manipulation
Coordinate geometry
Surface generation
Raster processing and modeling
Centralized spatial database management
Linear modeling and distribution analysis
Arc
Arcplot
Arcedit
COGO
TIN
Grid
Librarian
Network
There are six for concepts
that are pertinent to the
application of GIS technology
to environmental studies:
• Geographic data represen-
tation
• Topology
• Maps as the basis for GIS
data input and output
• Data resolution
• User interface
• Relational database
management systems
REFERENCES
The basic unit of data man-
agement in ARC/INFO is the
geo-dataset, which includes
the coverage, grid, and
triangulated integrated
network (TIN). Each geo-
dataset uses an associated
data model to define
locational and thematic
attributes for map features.
The data model (vector or
raster based) has its own set
of geo-processing and
modeling tools.
Polygons, lines, points,
nodes, and annotations are
features which, when
associated with thematic and
locational attributes, can be
used to represent many
types of mapped information.
The integration of various
data types is the strength of
GIS technology. Using
layers of data, researchers
are able to generate informa-
tion that realistically defines
conditions at a site. This
information is a key to
correct decision making at
Superfund and RCRA sites.
(1) Morehouse, S. The Architecture of ARC/INFO, ARC News, 12 (2). 1990
FOR FURTHER INFORM A TiON
For information on GIS Technology research and development at the EMSL-L V, contact:
qM"! O/V.
"V /
Mr. Mason Hewitt
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2377
For information about the Technology Support Center at the EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed by Clare L Gerlach,
Lockheed Environmental Systems & Technologies Company, Las Vegas.
-------
£EPA
Umiec States
Environmental Protection
Agency
Environments! Monitoring
Systems Laocraton/
P O Box S3478
Las Vegas NV 39193-3478
FECHNOLOGY SUPPORT PROJECT
Accessing
Geographic
Information
Systems
Technology
Introduction
Geographic Information
Systems (GIS) technology
has been used by the U.S.
Geological Survey and by
state and municipal govern-
ments for years. Recently,
its application to environ-
mental studies has become
apparent and growing
numbers of environmental
scientists are able to access
the power of GIS.
The user is able to analyze
data, query the system for
more information, and obtain
detailed databases upon
which accurate site assess-
ments can be made. Ques-
tions about the destination of
effluents, the location of
population groups, and other
environmental impact
determinations can be made.
Its power is in its ability to
relate attribute data to
cartographic features. This
allows data analysis that can
be used by decision-makers
to guide the course of an
investigation. This strength
makes it particularly appli-
cable to environmental
investigations, where
decisions must be based on
complexities of source,
extent, and matrix.
GIS can incorporate data-
bases from the U.S. Geologi-
cal Survey, aerial photo-
graphic information, mea-
surement results, and data
from municipalities and
utilities. Further, it can
incorporate historical data-
bases for comparisons. By
overlaying the digitized
information, GIS scientists
can produce accurate and
informative maps of a
location. GIS represents
data as points, lines, or
polygons. Types of data
input include transportation
features, geopolitical bound-
anes, streams, and topogra-
phy. This integrated ap-
proach is particularly perti-
nent to the characterization
of hazardous waste sites.
Man-made structures can be
superimposed upon natural
features to provide the
investigator with a complete
picture of an area of environ-
mental interest. By using
GIS, scientists can identify
areas that require closer
screening for hazardous
components.
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) was
the first EPA laboratory to
use GIS technology in
environmental applications.
Now, EMSL-LV is a center
for GIS research and devel-
opment and customizes GIS
use to the needs of the EPA
Regions and Program
Offices. There is a GIS
applications center in each
Region with in-house experts
to help Remedial Project
Managers, Site Assessment
Managers, and On-Scene
Coordinators.
The power of GIS technology
enhances the ability of
environmental decision-
makers to assess the extent
of contamination. GIS uses
an increasing amount of
information that is pertinent
to the characterization and
remediation of hazardous
waste sites.
The reverse side of this
Technology Support Center
Fact Sheet gives GIS con-
tacts at the EMSL-LV and at
each of the Regions.
2053ex93odc.fs
-------
REFERENCE
FOR FURTHER INFORMATION
A summary of GIS Support to Superfund, a U.S. EPA, EMSL-LV report, EPA/600/X-93/062
1993.
EMSL-LV publications Tech Memos 1-5
For information about the EMSL-L V GIS Center for Research and Development and for
copies of the documents listed above: write to:
Mr. Mason Hewitt
U.S. EPA
EMSL-LV
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2377
Mr. Rick Webster
U.S. EPA
EMSL-LV
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2199
Mr. Mark Olsen
U.S. EPA
EMSL-LV
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-3155
For information about the Technology Support Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
For GIS assistance at the Regional level, contact:
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U Project £
Region 1
Greg Charest
617-565-4528
Region 2
George Nossa
212-264-9850
Region 3
David West
215-597-1198
Region 4
James Bricker
404-347-3402
Region 5
Noel Kohl
312-886-6224
Region 6
David Parrish
214-655-8352
Region 7
R. Lynn Kring
913-551-7456
Region 8
Bill Murray
303-294-1994
Region 9
Mark Hemry
415-744-1803
Region 10
Ray Peterson
206-553-1682
The Technology Support Center fact sheet series is developed by Clare L Gerlach,
Lockheed Environmental Systems & Technologies Company, Las Vegas.
-------
&EPA
Un'ea States
Environmental Protection
Agency
Environmental Mcnitcnr.g
Systems LaDorator/
P O 3ox 93478
Las Vegas NV 89193-3478
Cc:cc~- ¦ =92
TECHNOLOGY SUPPORT PROJECT
Geographic
Information
Systems:
An
Overview
2080GR930DC FS
Introduction
The U.S. EPA is interested in
the development and utiliz-
ation of sophisticated tools
for the measurement and
analysis of contamination at
Superfund and RCRA sites.
Geographic Information
Systems (GIS) are systems
where geographic data des-
cribing the earth's surface
are managed, displayed,
manipulated, and analyzed
(1). GIS is able to analyze
spatial data, making it a
powerful tool for the analysis
of the source, extent, and
transport of various types of
contamination.
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) is the
Agency's Center for Re-
search and Development in
GIS technology. Work is
underway on the application
of GIS to site characteriza-
tion at various Superfund
and RCRA sites.
The ability to analyze com-
plex, spatial data makes GIS
technology interesting to a
growing user community
within environmental sci-
ence. Applications include
environmental monitoring,
modeling non-point runoff,
and landscape ecology. The
EPA's Environmental Moni-
toring and Assessment Pro-
gram (EMAP) is tapping into
the many capabilities of GIS
technology as it begins its
long-term evaluation of eco-
logical trends.
The heavy emphasis on
analytical manipulation of
spatial data is the main
characteristic that distin-
guishes GIS from other
technologies like computer-
aided design and electronic
mapping systems. Using
GIS, an analyst is able to
present a complete picture
of a site location, tiering
maps of streams, geo-politi-
cal boundaries, transporta-
tion routes, and topographic
information.
Data Analysis
The power of GIS to gener-
ate highly specialized
informational maps makes it
an effective method for
presenting information to
decision makers and to the
public. GIS is capable of
much more than generating
maps and presenting data.
Environmental studies
produce complex data that
are difficult to represent
verbally or visually. Using
GIS, environmental scientists
are able to interpret spatial
data, manage complex
databases, and use layers of
information from various
sources. Based on GIS,
analysts can produce a
realistic and understandable
visual analysis of a hazard-
ous waste site.
2080ex93odC
-------
Hardware, Software,
and People
GIS systems rely on a
relational database manage-
ment system to provide the
ability to query, manipulate,
and extract geographic
reference and attribute data.
This approach permits
standard statistical manipula-
tions of attribute data, as well
as logical and boolean
queries based on GIS
feature characteristics (2).
Some common analysis
capabilities include measure-
ments, attribute reclassifica-
tion, topological overlay,
connectivity operations,
coordinate transformations,
and surface analysis.
include a terminal to display
graphics, a central process-
ing unit, a digitizer to
manually trace data from
maps, a plotter to write
cartographic output, and a
tape drive to save and
export information. Other
GIS peripherals include
scanners, optical drives, and
image recorders. The trend
is toward workstations and
personal computers that
provide the power and
performance required by
GIS.
User interface functions
such as menus, scrolling
lists, and other graphic user
interface (GUI) building tools
may be supported by the
language processor.
Applications can be built to
simplify complex tasks,
providing decision support
tools to novice users. Some
GIS language processors
have the ability to access
other programs written in
higher language systems
such as Fortran and C,
using embedded routines to
access common blocks of
computer memory.
There is a growing need for
spatial analysis to be an
integral part of routine data
analysis and decision-
making. To meet this need,
GIS technology is migrating
to the desktops of applied
technologists in fields like
biology, economics, and
environmental science.
GIS hardware includes the
computer platform and
peripherals. Components
Reliability
Digitized data and the
informational maps that result
from GIS applications are
only as reliable as the quality
of the data that is input.
Whenever GIS is used for
decision-making, it is impor-
tant to state the confidence
levels of the information.
Some research effort is
underway to represent the
reliability of the data by
subtle differences in the
display characteristics.
REFERENCE
1. Understanding GIS: The Arc/Info Method. Environmental Systems Research Institute,
Inc., Redlands, CA. 1990.
2. Geographic Information Systems (GIS) Guidelines Document. Office of Information
Resources Management. U.S. EPA. 1988.
FOR FURTHER INFORMATION
For further information on GIS Technology research and development at the EMSL-LV, contact:
Mr. Mason J. Hewitt
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2377
vGAllO/V.
J
Vs
For information about the Technology Support Center at the EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed by Clare L. Geriach,
Lockheed Environmental Systems & Technologies Company, Las Vegas.
-------
&EPA
Introduction
Project Objectives
Umtea States
Environmental Protection
Agency
Environmental Monitoring
Systems LaDoratory
P O Box 93478
Las Vegas NV 39193-3478
Octccer ; 9S3
TECHNOLOGY SUPPORT PROJECT
The GIS
Planning
Process
2079GR930DC FC
Planning is an important step
in the characterization of con-
tamination at hazardous
waste sites. Thoughtful plan-
ning early in the process can
save time and money as the
characterization progresses.
The use of geographic infor-
mation systems (GIS) tech-
nology can provide the
analyst with valuable informa-
tion about a site. Because so
much information is available,
it is important that the analyst
ask the right questions and
access pertinent databases.
GIS is a complex tool that
requires planning in many
areas to avoid problems that
can affect the project's out-
come. Scientists at the
Environmental Monitoring
Systems Laboratory in Las
Vegas (EMSL-LV) have
isolated six areas essential
to the GIS project planning
life cycle.
They are:
• Define project objectives
• Identify analytical require-
ments
• Define data and hardware
requirements
• Determine data availability
• Resolve data development
issues
• Implement project plan
As with any analytical pro-
cess, the quality of the result
is dependent upon the
recognition of the exact
problem and the implemen-
tation of the correct steps in
addressing it. The GIS
software used by the U.S.
EPA is ARC/INFO.
Defining specific project
objectives reduces wasted
time and effort in the project
planning lifecycle. Project
objectives should encompass
every aspect of the project,
from data collection and
manipulation to data display
and archival. Not ail aspects
of a project are known in their
entirety at the onset of a
project, of course, so project
objectives should be flexible
enough to be customized as
more knowledge of the study
becomes available.
Sometimes very little is
known about the project at
the beginning of the study
and a preplanning data
gathering effort is necessary
to establish the facts.
Analytical
Requirements
Data and Hardware
Requirements
The next step in planning is
the identification of analytical
requirements. The defined
analytical requirement will be
used to specify more exact
standards for database data
quality, resolution, and scale.
This stage of the GIS plan-
ning process requires the
input of project staff and GIS
specialists. It is important
that the project staff commu-
nicate their exact needs to
the GIS experts. After the
requirements are estab-
lished, program management
staff should prioritize the
needs and establish measur-
able data quality objectives
to meet them.
GIS systems are used to
organize field data in a
spatial context that allows
decision makers to make
informed choices as the
study progresses.
After the analytical require-
ments are established, it is
possible to compile a detailed
list of data and hardware
needs. A data matrix of
needs and sources is helpful
in this planning step. At this
stage it is useful to consider
the attribute information
required for analysis,
minimum data resolution
and scale, data input and
output formats.
Hardware requirements
should be specified at this
point. Some key consider-
ations are the integration of
data from other sources,
data display needs, and the
types and functions of the
user interface. ARC/INFO
supports many different
types of graphic terminals
and their plotters. Data
visualization is affected by
the sensitivity and resolution
of graphics terminals and
printers.
-------
Data Availability
Data Development
Issues
Implementation
The project's analysis
objectives can only be met if
the data is available. The
degree to which GIS data are
available is related to the
resolution, scale, and compi-
lation date required by the
study. Another availability
factor is cost. Data may be
available in the sense of
existing but may be beyond
the cost restrictions of the
particular project. The data
needed for a project will fall
into one of three categories:
data you have, data some-
one else has, and data no
one has.
Data development may be
required to address the data
quality objectives of the
project. At this point, data
must be assessed to ascer-
tain their adequacy. Project
deadlines and data quality
objectives (DQOs) should be
reviewed at this time. The
personnel responsible for
critical decisions should be
involved in this adequacy
review. Key questions
should be asked. Are the
data adequate to meet the
DQOs of the project? Can
defensible decisions be made
based on the data at hand?
Is the data quality sufficient?
Is there enough time to
gather additional data if
necessary?
All aspects of the information
should be evaluated for cost
impact. Cost considerations
may include the acquisition
of data, travel costs, quality
assurance, contractor fees,
and all project management
costs.
The GIS project implementa-
tion phase carries out the
database development and
analysis objectives. The
database design defines the
database structure, its
characteristics, coverage
attnbute coding scheme, data
models, and automation
methods. The resulting
design document should
determine if the GIS data-
base meets the project's
analytical objectives. The
data capture and automation
phase carries out the data-
base design through data
acquisition and integration of
data into the GIS system.
The database design in-
cludes digitizing analog
maps, converting digital data
into GIS format, and correct-
ing and coding data.
Once the database is
complete, a test of the GIS
analysis functions is per-
formed. When the staff are
satisfied with the system's
ability to meet the analytical
requirements of the project,
database production can
begin.
REFERENCE
GIS Technical Memorandum 1; GIS Planning and Data Set Selection, U.S. EPA, EMSL-LV.
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r-vr^nrnemai Prc:ec:,cn Systems _aocra:cry
Agency p'O Box 93473
Las Vegas NV 89*93-34.78
OFFICE OF RESEARCH AND DEVELOPMENT TECHNOLOGY SUPPORT PROJECT
&EPA Remote Sensing
in Environmental
Enforcement
Actions ^
CAPABILITIES
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) and its
Environmental Photographic
Interpretation Center (EPIC)
support EPA litigation actions
through remote sensing
technology. In the course of
conducting environmental
analyses EPIC has acquired:
1) a large library of remote
sensing and resource
documentation derived
from archival sources
nationwide. The library
collection includes more than
150,000 frames of imagery
dating from the late 1930s to
the present, covering areas
throughout the United States.
In addition to the imagery,
completed remote sensing
reports and other resource
data such as maps, soil
surveys and cartographic data
are available for documenta-
tion in legal proceedings.
2) a technical staff experi-
enced in the analysis of
imagery in a number of
discipline areas: wetlands,
geology, environmental site
analysis, as well as photo-
grammetry. Over the years
the technical staff has gained
substantial experience in the
analysis of imagery and its
interpretation using modern
computer technology.
3) a modern integrated
system of imagery collec-
tion and analysis equip-
ment. EPIC has a computer
driven analytical stereo
plotter and a digital video
plotter, both of which en-
hance accurate photogram-
metric measurements of
environmentally significant
features. Additionally,
geographic information
systems (GIS) capabilities
permit highly accurate
integration of both spatial and
positional data that can bear
legal scrutiny.
APPLICATIONS TO
EPA ENFORCEMENT
ACTIONS
EMSL-LV has provided vital
technical support to a variety
of EPA mandated cases.
They include civil and crimi-
nal actions brought by EPA
Regional offices, the National
Enforcement Investigations
Center (NEIC), and the
Offices of Inspectors Gen-
eral.
EPIC has supported general
counsels of various EPA
Regions, U.S. Department of
Justice attorneys, and state
attorney generals offices.
Specific cases have involved
prosecutions brought under
CERCLA, RCRA, Clean
Water Act, and National
Environmental Policy Act. In
almost all instances, the
actions culminated in out-
comes favorable to EPA
interests. The penalties have
included cost recoveries in
civil proceedings, corporate
fines, and fines and prison
sentences to individuals in
criminal proceedings.
12MEX920DC
-------
SERVICES
EPA/EMSL-LV facilities -
•EPIC East and West —
operate under conditions of
continuous security. Both
facilities are vaulted, and 24-
hour round-the-clock protec-
tion is maintained at each
location. The following are
some of the services pro-
vided and procedures
observed in supporting
environmental enforcement
actions.
• Acquisition, indexing and
archiving of imagery,
topographic maps and all
photo-derived documents.
• Chain-of-custody documen-
tation of imagery, which
records the handling of the
imagery from supplier,
through shipper and in-
house handling, to
customer receipt.
Certified authenticity of
imagery and product
documents used in
courtroom testimony.
Depositions or affidavits
by expert witnesses,
trained and experienced
in environmental
disciplines.
PRODUCTS
The products provided in
supporting environmental
enforcement actions include:
historical and current imag-
ery, enlarged photographs,
digital and analog remote
sensing products, environ-
mental reports, and mounted
graphical exhibits for court-
room display. The prepara-
tion of photographic and
graphic courtroom exhibits is
under conteaJtecUaboratory
conditions and careful
supervision. All graphical
displays can be easily
annotated for full visual effect
in the various litigation or
testimonial forums.
REFERENCES
Remote Sensing in Hazardous Waste Site Investigations and Litigation TS-AMD-86724;
December 1988 (Revised).
FOR FURTHER INFORMATION
For further information on remote sensing use in environmental enforcement, contact:
Donald Garofalo
U.S. EPA-Environmental Photographic Interpretation Center
Building 166, Bicher Road
Vint Hill Farms Station
Warrenton, Virginia 22186-5129
(703) 341-7503
For information about the Technology Support Center at EMSL-LV, contact:
G^IO/V.
lOGi ^
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las V^gas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
v>EPA
ur tea Dia:es
Environmental Protection
Agency
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Systems ^aoorator/
P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Topographic
Mapping for
Environmental
Assessment
TECHNOLOGY SUPPORT PROJECT
INTRODUCTION
The location, extent, and
historical change in the
nature of hazardous waste,
sites is of great importance to
the Environmental Protection
Agency, and can be docu-
mented through the creation
of topographic maps. The
Environmental Monitoring
Systems Laboratory in Las
Vegas is the Agency's center
for mapping and related
remote sensing technologies.
Topographic (elevation)
maps are simple, effective,
and graphic tools for record-
ing the quantitative and
qualitative characteristics of
hazardous waste sites.
These maps are most often
created from aerial photo-
graphs and, since national
archives of coverage date
back more than fifty years,
maps can be created that
reflect historical site condi-
tions.
TECHNIQUE
A typical topographic map-
ping project begins with a
request from an RPM to the
EMSL-LV Advanced Monitor-
ing Systems Division (AMD).
The EMSL-LV provides a
cost estimate and arranges
for all necessary geodetic
surveys, aerial photographic
overflights, and map produc-
tion. No permission is
needed for a flyover, so aerial
photography is of particular
value in situations where
uncooperative owners deny
intrusive sampling. A spe-
cially calibrated aerial camera
is used to insure accurate
photography for later use in
the map production process.
Once the film is developed, it
is placed in a special instru-
ment (stereoplotter) which
creates a model of the terrain
to produce a contour map.
The map may be generated
as hardcopy, or in digital form
for later use with Geographic
Information Systems (GIS).
The same aerial photographs
can be interpreted to assess
the remediation actions at the
site.
SCOPE
In addition to basic positional
information about ground
elevation and locations of
objects, maps can serve as
the base for a targeted
sampling grid, or for record-
ing specialized information
such as land disposal activity,
population distribution,
geologic fractures, vegetation
communities, wetlands
delineation, and land use.
When compared with histori-
cal aerial photographs these
maps can provide both
qualitative and quantitative
information on changes in
volume and elevation (e.g.,
last year there was a mound
three times larger than the
present one; or, between
1988 and 1990, there were
100,000 cubic yards of
material placed in the land-
fill). Topographic information
is entered into ARC-INFO
(EPA's GIS software) for
future referral. The informa-
tion on these maps can
provide answers to critical
environmental questions
such as the probable sources
of contamination and the
ultimate destiny of dis-
charges.
1661EX90
-------
ADVANTAGES AND
LIMITATIONS
Topographic mapping is a
mature technology that is
expanding to meet the needs
of the environmental commu-
nity. Advances in computer
technology and optical
sciences have enhanced
remote sensing capabilities
over the years - and continue
to do so.
Advantages
Legally defensible data
Permanent historical record
Digital or analog format
Geographic relationships are
clearly demonstrated
Quantitative measurements
can be made
Limitations
Seasonal and weather restric-
tions
Complexity of technology
FUTURE PLANS
Remote sensing and map-
ping technologies continue to
develop and hold great
promise for practical environ-
mental usage. The basic
topographic mapping process
is being augmented by a
series of related monitoring
techniques that will provide
new thematic mapping
products. Among these are:
the use of orthophotography
which is hard-copy imagery
corrected to map-quality
standards; land use/land
cover mapping from satellite
data; and the development of
various digital products in a
Geographic Information
Systems format.
The increased need for
accurate information will
continue to drive remote
sensing and topographic
mapping growth in the 1990s.
REFERENCES
U.S. Environmental Protection Agency. 1984. Photogrammetric Mapping Program for Haz-
ardous Waste Sites. An EMSL-LV publication.
Remote Sensing and Interpretation, Lillesand, T. M., and R. W. Kiefer, John Wiley and Sons,
1979, especially Chapter 5.
FOR FURTHER IN FORM A TION
For specific information on topographic mapping, contact:
Mr. Paul Olson
EPIC-LV
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, Nevada 89193-3478
(702) 798-2288
FTS 545-2288
FAX/FTS 545-2692
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For further information on technology support, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270/734-3207
FTS 545-2270
FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
xvEPA
Ur.itad States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O Bo* 93478
Las Vegas NV 89193-3478
Feor-^ar/ 1552
OFFICE Of RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT project
Remote Sensing
Support for RCRA
INTRODUCTION
Since the passage of the
Resource Conservation and
Recovery Act (RCRA), the
U.S. EPA has employed
aerial remote sensing tech-
niques to assess the suitabil-
ity of sites for disposal of
hazardous wastes. Remote
sensing (interpreted aerial
imagery) provides key
information necessary for
RCRA personnel to respond
to problems at waste disposal
sites, to assess the risks of
those sites to their neighbor-
ing communities, and to
evaluate new sites proposed
for the disposal of hazardous
waste. Aerial photography
and other sensor imagery are
the most economic source of
information that is required by
Agency officials for permit
reviews, litigation support,
site operations monitoring,
and general environmental
assessments. Acquisition
and interpretation of aerial
imagery data for this and
other Agency programs are
conducted by the Environ-
mental Monitoring Systems
Laboratory in Las Vegas
(EMSL-LV).
The EMSL-LV provides aerial
imagery acquisition and
interpretation support for
hazardous waste site analy-
sis to the Regional offices
and to the Office of Solid
Waste and Emergency
Response (OSWER). Typi-
cal OSWER activities that
have been supported include
emergency response to
hazardous materials release
situations, current site
condition assessments,
historical reviews of site
development, waste site
inventories for large geo-
graphical areas, topographic
mapping of sites, and crimi-
nal and civil litigation under
RCRA. The remote sensing
support provided is typically
paid for by reimbursable
funding from the office
supported.
Remote sensing is a key tool
for addressing RCRA en-
forcement and response
issues. The Environmental
Photographic Interpretation
Center (EPIC), a branch of
the Advanced Monitoring
Systems Division (AMD) at
EMSL-LV, provides:
• A team of scientists with
the critical skills that are
required for unique environ-
mental/enforcement issues;
• The applications research
that is necessary to keep
the Agency at the state-of-
the-art and a capability to
transfer this technology to
the Regions; and,
• The ability to respond
quickly to emergency spills
of hazardous materials.
ENFORCEMENT
REQUIREMENTS
The EMSL-LV program also
supports special enforcement
requirements. Once a site
analysis is completed by
EMSL-LV and a final report is
produced, it may be several
years before the associated
RCRA case comes up for
litigation. For more that 17
years, the EMSL-LV has
contributed to the production
and maintenance of hazard-
ous waste disposal site
image analysis reports and
records. The EMSL-LV
program thus provides a
team with an "institutional
memory" that otters reliable
and consistent support to
enforcement cases through-
out extended litigation under
RCRA. In this role, the
EMSL-LV provides support to
EPA's National Enforcement
Investigations Center (NEIC),
to Regional Offices of Crimi-
nal Investigation (OCI's), and
to the Department of Justice.
EPA's attorneys prefer using
a centralized EPA remote
sensing program for criminal
prosecutions. In their opin-
ion, such a program is
sensitive to the security
requirements of enforcement
cases, is involved in fewer
conflicts of interest, uses
proper chain-of-custody
procedures for handling
cameras, film, and photo-
graphs, and develops long-
term working relationships
with the EPA attorneys.
10S3EX92
-------
TECHNOLOGY
TRANSFER
ACTIVITIES
The EMSL-LV also provides
technology transfer support
to EPA Headquarters and
Regional program offices in
the form of RCRA training
workshops and technical
advice. This includes send-
ing EMSL-LV scientific staff
to the Regions to demon-
strate the use of interpreted
aerial imagery in addressing
RCRA requirements in the
Region. This is an on-going
activity conducted on a
regular basis to ensure that
new RCRA stafl are property
informed and current staff an
kept up-to-date with the
technologies.
EMERGENCY
RESPONSE
CAPABILITY
EPIC also uses the capability
of the EMSL-LV to respond to
emergency requests, usually
in response to hazardous
material release or other
emergencies at waste sites.
These actions provide quick
pictorial information on
conditions at the site. Infor-
mation on the extent and
location of visible spillage,
vegetation damage, and
threats to natural drainage
and human welfare are typical
of the types of information
gathered during emergency
response activities.
EPIC, through its fully opera-
tional photo processing and
image analysis facilities in
Warrenton, VA, and
Las Vegas, NV, is on call to
respond to emergency
situations and prepared to
work around the clock to
process aerial photography,
analyze the film, document
the analysis results, and ship
the results to the requester
as soon as possible.
ENFORCEMENT
The Agency has special
enforcement requirements for
civil and criminal litigation
and many of these require-
ments have direct policy
implications. For example,
there are specific security
requirements of EPA criminal
cases, as outlined in the
Federal Rule of Criminal
Procedure 6{e), which
requires protection of grand
jury material. EMSL-LV
provides protection of these
materials through the use of
proper chain-of-custody
procedures which is crucial t
the success of EPA cases.
FOR FURTHER INFORMATION
For further information about the custom service available through the EMSL-L V for RCRA
sites, contact:
Regions 1*5
Mr. Gordon Howard
(703) 349-8970
FAX 557-0243
Regions 6-10
Mr. Phil Arberg
(702) 798-2545
FAX 545-2692
,xC>TI0A/.v
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-------
Ur.iiec Stales
Environmental Protection
Agency
cnvifcn~,en;al Mentoring
Systems Laocrator/
P.O. Box 93478
Las Vegas NV 89193-3473
OFFICE OF RESEARCH AND DEVELOPMENT
Wetlands Delineation
for Environmental
Assessment
c/EPA
INTRODUCTION
The Environmental Photo-
graphic Interpretation Center
(EPIC) at the Environmental
Monitoring Systems Labora-
tory-Las Vegas (EMSL-LV)
provides current and histori-
cal wetlands analyses that
locate, characterize, and
document historical dredge or
fill activities in wetlands.
Aerial photographs offer a
synoptic view of wetlands
and their surrounding envi-
ronments and form a perma-
nent record of present and
past conditions. Precise
quantitative measurements
can be derived from aerial
photos that aid field work by
displaying relationships not
readily apparent on the
ground. Uses for extracted
data range from general
regional planning to legally
defensible presentation of
data.
EPIC wetlands analysts tap
years of experience in
photointerpretation of varied
wetlands habitats. Collateral
information on soils, local
hydrology, and vegetation is
always utilized to ensure the
accuracy of the delineations.
Field verification may be
used to enhance the accu-
Cctccer ' 99"
TECHNOLOGY SUPPORT PROJECT
racy of the delineations.
Areal measurements of data
can determine loss of wet-
land habitat, length of con-
structed drainage channels,
or other pertinent information.
Various levels and formats of
wetlands delineations are
available as dictated by the
needs of the requester.
Overlays to either aerial
photos or topographic maps
may be produced, or the data
can be converted to digital
form for use within a Geo-
graphic Information System
(GIS).
SCOPE
Wetland/Upland Boundary
Analysis
Determination of a wetland/
upland boundary is the
simplest analysis. This level
of analysis is used to locate
wetlands and off-site drain-
age patterns. It is typically
requested for a specific area
surrounding sites and usually
involves the most current
year of photography, but
multiple years can be ana-
lyzed if change detection is
needed.
Detailed Analysis
A detailed wetlands analysis
is requested when informa-
tion is needed on vegetation
types in the wetlands and
deepwater habitats classifica-
tion system developed by
Cowardin et al. (1989) for the
U.S. Fish and Wildlife Ser-
vice. Analyses of single or
multiple years of coverage
are performed.
Section 404 Support
Section 404 of the Clean
Water Act protects wetlands
from unpermitted dredge and
fill activities. Analyses
involve field work using
jurisdictional delineation
procedures. Wetlands are
classified using the full
Cowardin et. al. (1979)
classification system. Two
types of analyses are used in
support of this program.
Enforcement
Court support can be pro-
vided for enforcement cases
where wetlands have been
dredged or filled and no
permit had been issued.
Using historical photographs
and field verification, refer-
ence wetlands having the
same photographic signature,
soils, and hydrology as the
dredged or filled wetlands are
used to confirm the classifica-
tion of the filled or dredged
wetlands. Current overflights
of the site are generally
acquired to ascertain current
conditions. To detect
change, at least 2 years of
photography are analyzed.
Area measurements of
wetlands loss and change by
type are calculated using
Geographic Information
Systems software. Should
legal proceedings be re-
quired, graphic displays and
expert witness testimony are
provided.
Advance Identification
In support of the Advance
Identification process of 404,
delineation of wetlands on
overlays of current photo-
graphs or base maps are
available. These studies are
a cost-effective way to
identify wetland habitat in
advance of permit application
and evaluation.
1141EX91
-------
Advantages
• More cost effective than
intense field sampling
• Legally defensible
• Verifies existence of
current or historical wet-
lands
• Detection of change
ADVANTAGES AND
LIMITATIONS
Historical aerial photographs
are often the only means of
establishing the prior exist-
ence of wetlands for sites
that have been dredged or
filled. Progress in computer
technology has enhanced the
accuracy of both presentation
and measurement of wetland
change detection data and
subsequent transfer to maps.
• Photo coverage of critical
years
Limitations
• Visibility obscured by snow,
cloud cover, and leaf-on
conditions
• Available photography may
exhibit extremes in hydrol-
ogy (drought and flood)
• Lack of photo coverage for
critical years
FUTURE PLANS
Remote sensing for wetlands
delineation and mapping is
an expanding field. Improve-
ments in the resolution of
aerial photography and
associated technologies will
expedite the delineation
process. With the introduc-
tion of photogrammetric
instruments into this mapping
discipline, precise planimetric
and volumetric measure-
ments can be performed in
support of EPA needs. By
converting photointerpreted
data into digital format, they
can be combined with data
from diverse sources result-
ing in spatial information
useful for environmental
decision making.
REFERENCES
Cowardin, L. M., V. Carter, F. C. Golet, and E. T. LaRoe. Classification of Wetlands and
Deepwater Habitats of the United States, U.S. Department of the Interior, Fish, and Wildlife
Service, FWS/OBS-79/31,1979.
FOR FURTHER INFORMATION
For further information on wetlands mapping capabilities contact the Environmental Photo-
graphic Interpretation Center at:
Regions 1-5 Regions 6-10
Mr. Gordon Howard Mr. Phil Arberg
(703) 349-8970 (702) 798-2545
FTS 557-3110 FTS 545-2545
FAX 557-0243 FAX 545-2692
For information about the Technology Support Center at EMSL-LV, contact:
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Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed by Clare L Gerlach,
Lockheed Engineering & Sciences Company, Las Vegas.
-------
j rcr,T,en,iai P'c:=c;:
vyEPA
INTRODUCTION
TECHNIQUE
THEMATIC MAP
PRODUCTS
3/s:e~s L^ccsxry
P'O Box 93^73
Las Vegas NV 39193-3473
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Photogrammetry
for Environmental
Measurement
CLjjL.es O,
"/v?°rfrV^ a
The Environmental Monitor-
ing Systems Laboratory, Las
Vegas (EMSL-LV) has an
active remote sensing
department, capable of
responding to all Regional
requests tor obtaining and
interpreting aerial photogra-
phy Photogrammetry is
defined as the "art and
science of obtaining reliable
measurements from photo-
graphs" (American Society
for Photogrammetry and
Remote Sensing, 1991).
Most small and medium scale
maps are made frc aerial
photographs, and pnotogram-
metric sciences are a funda-
mental part of modern map
making. The aerial photo-
graphic holdings in the EPA
and other agencies of the
federal government are a
wealth of spatial and tempo-
ral data about environmental
conditions and processes.
EMSL-LV currently provides
qualitative information that is
interpreted from aerial photo-
graphs to characterize hazard-
ous waste sites, analyze
wetlands, identify ecological
resources and to meet a
number of environmental
monitoring needs. EMSL-LV
has now acquired the capabil-
ity to supply highly accurate
measurement information for
similar applications.
Photogrammetric data are
produced on very precise
photo-measurement devices
called analytical
stereoplotters. These
devices, typically calibrated
to the micron level, enable
the scientist to create com-
plex mathematical models
that correct for known
distortions in the photo-
graphs. From these three-
dimensional photo models,
highly accurate measure-
ments and positional data
can be derived for mapping
and analytical purposes.
These data can be produced
in digital format directly for
input in a Geographic Infor-
mation System (GIS).
Cartographic information can
be produced from aerial
photographs to meet National
Map Accuracy Standards.
The information can be
traditional map features such
as roads and hydrology or
special map layers such as
historical hazardous waste
site activity and fractures in
the bedrock. Any information
that can be derived from the
aerial photo can be accu-
rately mapped in a digital
format. Once the photo
model is established, the-
matic information repre-
sented by points, lines, and
polygons can be input directly
in digital format without
transfer to a hard-copy map
and digitizing from the map
base. This saves time and
reduces errors.
MENSURATION
PRODUCTS
Exact measurements can be
accomplished on an analyti-
cal stereoplotter to help
characterize activity of
environmental interest. For
example, in studying hazard-
ous waste sites, the volume
of waste accumulation and
changes in this volume are
needed to evaluate remedial
options. Also, precise
distance and area measure-
ments can be utilized tor risk
assessment and other site
characterization activities.
113GEX9200C
-------
PRECISE LOCATION
OF FEATURES
Any feature that is observ-
able on an aerial photograph
can be accurately referenced
to a coordinate system.
Photogrammetry can be
extremely useful for collecting
and recording the coordinate
data that are required by the
EPA Locational Data Policy.
Information that is not readily
visible on photographs, such
as property boundaries or
pipelines locations, can be
superimposed digita"v onto
the photo model for special
mapping or interpretive
purposes.
Cartographic information that
depicts the elevation of the
land surface, such as the
contour map or the digital
elevation model, can be
produced by photogrammet-
ric techniques. The resolu-
tion of this data can be
tailored to the specific needs
of the project.
ADVANTAGES
Photogrammetric products
generated from current and
historical photos have the
same advantages and data
that are interpreted from air
photos: they form a perma-
nent record of present and
past conditions, they are
defensible in court, and they
serve as valuable aids to site-
specific field work. The
ability to provide quantitative
measurements as a supple-
ment to qualitative
photointerpretation products
will significantly enhance
the products and services
available to the EPA
community.
FUTURE PLANS More of the basic photogram- Also, the use of digital incorporated into future
metry and photointerpretation imagery in the photogram- products as will the use of
products will become avail- metric process is currently digital photography in the GIS
able in digital, GIS formats. being researched and will be environment.
REFERENCE
American Society of Photogrammetry, 1980, Manual of Photogrammetry, 4th Edition, Chester
C. Slama, Editor-in-Chief, American Society of Photogrammetry, Falls Church, VA.
FOR FURTHER INFORMATION
For further information on photogrammetry, contact the Environmental Photographic Interpre-
tation Center at:
Regions 1-5 Regions 6-10
Mr. Gordon Howard Mr. Phil Arberg
(703) 349-8970 (702) 798-2545
FAX 557-0243 FAX 545-2692
For information about the Technology Support Center at EMSL-LV, contact:
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SEPA
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Systems Laboratory
? O Box 93-173
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Global Positioning
System (GPS)
Technology ^
TECHNOLOGY SUPPORT PROJECT
INTRODUCTION
Global positioning system
(GPS) technology is a
satellite-based radio position-
ing and time-transfer system
that can provide accurate,
three-dimensional geographic
positioning anywhere on the
earth's surface. Developed field of environmental sci-
by the Department of De-
fense, this technology was
designed primarily for military
navigational systems, but
there are numerous
geocoding applications in the
ence. GPS is an emerging
technology in geodesy,
geography, surveying, and
environmental monitoring and
analysis.
THE EPA
L0CAT10NAL DATA
POLICY
Data collection in environ-
mental monitoring is affected
by spatial considerations.
With the Agency's wide-
spread use of geographic
information systems (GIS) for
environmental analyses, the
quality of the geographic
reference of database items
becomes central to the quality
of the overall scientific
analyses.
In May 1990, after Agency-
wide review, the EPA adopted
the Locational Data Policy
(LDP) with the purpose of en-
suring the collection of accu-
rate, fully documented latitude/
longitude coordinates as part
of all Agency-sponsored data
collection activities. The EPA
accuracy goal has been estab-
lished at 25 meters and the
best collection method is cur-
rently considered to be GPS
(EPA 1991).
THE SCIENCE OF
SATELLITE
POSITIONING
By using radio signals from a
constellation of earth-orbiting
satellites, earth-based
receivers can compute highly
accurate three-dimensional
geographic coordinate
positions. Terrestrial posi-
tions can be determined
using different instruments.
GPS utilizes satellite tracking
and ranging to determine a
point's, three-dimensional
geocentric coordinates.
If data on the satellite geom-
etry, position, and movement
(called ephemeral data) are
known, the distance to an
earth-based receiver can be
geometrically calculated by
measuring the time it takes
for the radio signal to reach
the receiver. This type of
positioning is only possible
because of the accuracy and
speed of modern clocks and
computers. Ephemeral data
are constantly monitored by a
network of earth tracking
stations and relayed back to
the satellite where they are
included in the transmitting
signal and tracked by the GPS
receiver. If this ranging
process is repeated constantly
from several satellites, and
known errors caused by clock
timing and atmospheric effects
are modeled, a precise posi-
tion can be calculated and
referenced to a known datum
and coordinate system (Wells
et al., 1986).
HOW ACCURATE IS
IT?
Accuracy depends on several
factors including the design
of the receiver. There are
two general classes of GPS
receivers: navigation and
geodetic. By employing two
or more GPS receivers with
another that is located over a
known geodetic control point,
navigation grade instruments
can routinely yield accuracies
in the 2-5 meter range. The
geodetic quality units can
compute coordinates with
millimeter level accuracy.
13420(91
-------
APPLICATIONS
Apart from the traditional
types of geocoding, surveying,
and the collection of accurate
latitude/longitude coordinates,
one of the main applications of
this technology is in the area
of GIS. GPS technology
provides a means of
evaluating and quantifying the
spatial accuracy of digital map
data as well as creating digital
cartographic data structures.
Potential products and
application areas include:
• Direct Digital Mapping -
Portable GPSs can be
hand-carried or mounted on
vehicles to create digital
data structures that can be
used as direct input into GIS
systems. The system is
used to update existing map
data, provide highly accu-
rate subsections, or create
entirely new map products.
Field Navigation - Field
sampling teams can use
GPS to easily and accu-
rately record the location of
specific sampling locations
or to navigate back to a
previous sampling point
even when surface markers
have been disturbed or are
no longer present.
Quality Control - A carefully
planned GPS survey can
provide first order control
locations which can then be
utilized to assess the
spatial quality of other
thematic overlays that have
been developed for the
database or to geo-
reference raw data layers,
such as satellite or aerial
images.
Network Modeling - Kine-
matic (mobile) positioning
techniques can be used to
create network structures
with much greater accuracy
and precision than is
currently possible. Spatial
variations in movement and
rate, and time series
analysis can be acquired at
greater data resolutions.
Photogrammetric Control
Photogrammetry and
cartography often remain
the most cost-effective
methods of creating
thematic maps. The ease
of establishing a control
configuration for existing
aerial photographs with
GPS technology as op-
posed to traditional survey-
ing methods cam result in
significant savings in cost,
time, and manpower.
REFERENCES
Wells, D. E„ N. Beck, D. Delikaraoglou, A. Kleusberg, E. J. Krakiwsky, G. Lachapelle, R. B.
Langley, M. Nakiboglu, K. P. Schwarz, J. M. Tranquilla, and P. Vanicek, Guide to GPS Posi-
tioning. Canadian GPS Associates, Fredericton, N.B., Canada, 1986.
U.S. Environmental Protection Agency, Locational Data Policy Implementation Guidance -
Draft. Office of Information Resources Management, Washington, D.C. 20460,1991.
FOR FURTHER INFORM A TION
For further information about GPS systems or applications to a specific environmental
application, contact Terrence Slonecker or Mason Hewitt.
Terrence Slonecker
Environmental Monitoring Systems
Laboratory-Las Vegas/EPIC
166 Bicher Road
Vint Hill Farms Station
Warrenton, Virginia 22186
FAX (703) 557-0243
FTS 557-3111
Mason Hewitt
Environmental Monitoring Systems
Laboratory-Las Vegas
P.O. Box 93478
944 East Harmon Avenue
Las Vegas, Nevada 89193
FAX (702) 545-2692
FTS 545-2377
" OGV $
For information about the Technology Support Center at EMSL-LV, contact:
Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed by Clare L. Gerlach,
Lockheed Engineering & Sciences Company, Las Vegas.
-------
f/EPA
INTRODUCTION
DATA SOURCES
Urrsc oiaies
Environmental P-otection
Agency
znvironmentai Mon.;or~g
Systems LaDoratcn/
P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Historical Maps
and Archiving for
Environmental
Documentation
TECHNOLOGY SUPPORT PROJECT
The location, extent and
history of activities at hazard-
ous waste sites is of great
interest to the U.S. Environ-
mental Protection Agency
and can be documented
through the analysis of
historical records such as
aerial imagery, historical and
thematic maps and other
cartographic data. Since its
inception, the U.S. EPA's
Environmental Monitoring
Systems Laboratory through
its Las Vegas, Nevada
headquarters (EMSL-LV) and
Warrenton, Virginia field
station has been collecting
and analyzing these data
sources for environmental
site analyses and civil and
criminal actions. Cases are
brought by the Department of
Justice, FBI, and National
Enforcement Investigations
Center. Prosecutions related
to CERCLA, RCRA, National
Environmental Policy Act,
and Clean Water Act viola-
tions serve as support for
EPA Regional offices' investi-
gations at hazardous waste
sites across the country.
Aerial imagery is the corner-
stone data source used by
EMSL-LV during the comple-
tion of environmental site
analysis. Historical aerial
photography records the
evidence of past commercial
or industrial activities as well
as changes in topography,
hydrology and vegetation
brought about by industrial
development. Aerial photo-
graphic coverage dating back
to the late 1920s is available
for portions of the industrial-
ized U.S. Other types of
aerial imagery used at EMSL-
LV include color infrared
photographs (useful in
detecting vegetation stress)
and thermal infrared imagery
which records qualitative
variations in surface tempera-
tures and can be used to
identify leachate discharge
points, past disposal activi-
ties, and subsurface pipe-
lines. Historical maps date
back to the mid 1850s and
consist of U.S. General Land
Office land surveys, U.S.
Army Corps of Engineers river
and harbor charts, fire insur-
ance maps and early U.S.
Geological Survey topo-
graphic maps (late 1880s).
Thematic maps such as soil
surveys and bedrock or
surficial geology maps date
back to the turn of the century
and can provide information
on the subsurface environ-
ment which may in turn
measure the migration of
contaminants in ground water.
ACQUISITION AND
ARCHIVING
Historical aerial photographs
are available from federal
agencies (such as USDA,
USGS, NOAA, and USEPA),
state agencies, and private
vendors responsible for their
production. Archival aerial
photographs from some
federal agencies are stored
at the National Archives in
Washington, D.C. Aerial
photographs acquired from
the above sources are
indexed and added to EMSL-
LV's film archive, which
currently includes over
150,000 frames of imagery.
When current photography is
required, EMSL-LV initiates
an overflight of the site being
studied. These overflight
photographs are indexed in
the EMSL-LV film archive.
Historical maps are available
through a number of sources
such as the National Ar-
chives, Library of Congress,
state libraries, university
libraries, and state and
county offices. Thematic
maps are available from the
agency responsible for their
production, e.g., USDA SCS
Soil Surveys, USGS Geologic
Quadrangle Maps. These
maps are acquired and
cataloged as collateral data
and remain with the EMSL-
LV library-filed project folder.
Historical land use data
including census tracts are
available at the National
Archives, as well as state or
university libraries, and can
be acquired to support land-
use mapping.
1307EX9200C
-------
APPLICATIONS
Analysis of aerial photo-
graphs can reveal information
regarding the activities,
sources, and positions of
stored or buried hazardous
materials or wastes, the
possible pathways of con-
taminant migration, and the
potential receptors of migrat-
ing contaminants. Historical
and thematic map sources
provide information regarding
pre-aerial photography site
activities or subsurface or soil
conditions which may affect
the migration of contami-
nants. Aerial photographs
provide information which,
when combined with that
obtained from analysis of
historical and thematic maps
and other cartographically
related data, is often more
accurate and complete. This
information provides a
substantial supplement to
company records or em-
ployee memories. As such,
photographic data sources
are a vital part of any envi-
ronmental site analysis.
REFERENCES
Mata, L., and Fanelli, D., 1991. Environmental Property Assessments Utilizing Aerial Photogra-
phy. In Proceedings, Association of Engineering Geologists, 34th Annual Meeting p 301 -310.
Lyon, J. G., 1987. Use of Maps, Aerial Photographs, and Other Remote Sensor Data for
Practical Evaluations of Hazardous Waste Sites. Photogrammetric Engineering and Remote
Sensing V53, p 515-519.
Garofalo, D., and Wobber, F. 1974. Solid Waste and Remote Sensing. Photogrammetric
Engineering V40, p 45-49.
Erb, T. L. and others, 1981. Analysis of Landfills with Historic Airphotos. Photogrammetric
Engineering and Remote Sensing V47, p 1363-1369.
FOR FURTHER INFORMATION
For further information about accessing historical remote sensing information, contact:
Mr. Donald Garofalo
U.S. EPA-EPIC
Building 166 Bicher Road
Vint Hill Farms Station
Warrenton, VA 22186-5129
(703) 341-7503
For information about the Technology Support Center at EMSL-LV, contact:
VC*'°/VV
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Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
c/EPA
ur;:ec 3ia:es
rrvironmental Proiec!ion
Agency
zrvircrr-erra1 Mcri:cr;ng
5ys;ems Laoora;cry
P.O Box 93478
Las Vegas NV 89193-3478
Ncve.-ce-
OFF1CE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Field Screening
Methods for
Radioactive
Contamination
jxrxnjxn^r
INTRODUCTION
The complexity of hazardous
waste sites presents a
challenge to field scientists
and decision makers in the
remediation process. There
is growing concern in the
technical and secular com-
munities about the likelihood
of radioactive contaminants
at sites previously thought to
contain only organic or
inorganic material. Hazard-
ous waste site problems can
be described broadly as:
• Low level without radioac-
tive contamination
• High level without radioac-
tive contamination
• Low level with low level
radioactive contamination
• Low level with high level
radioactive contamination
• High level with low level
radioactive contamination
• Radioactive contamination
only
• High level with high level
radioactive contamination
Surveys are recommended
for sites that are suspected of
containing radioactive waste.
This cautionary measure can
identify problems early in the
site characterization proce-
dure and can isolate areas
that require special care in
the remediation program.
Portable instruments are
available that will determine
the presence of radioactive
hot spots in a quick, semi-
quantitative manner. These
instruments are not isotope
specific, but do identify the
source as an alpha, beta, or
gamma ray emitter.
INSTRUMENTATION
Several portable instruments
are commercially available
that can detect alpha, beta,
and gamma radiation. The
alpha counter is a separate
unit from the beta/gamma
counter. Each is battery
operated, smaller than a
shoebox, and easily man-
aged by one field scientist.
The beta/gamma counter
operates in two modes: with
the shield closed, it detects
gamma rays; with the shield
open, it detects beta plus
gamma rays. The amount of
beta radiation can be deter-
mined by the subtraction of
gamma from beta plus
gamma. The readings are
displayed on an analog meter
in millirems/hour or counts/
minute.
Another device that is
amenable to field survey use
is the portable ion chamber.
It is a hand-held instrument
with charged gas in a cham-
ber and is useful for the
detection of gamma radiation.
A "pancake" detector is often
used for quick screening of
clothing and flat surfaces. It
is sensitive to beta and
gamma radiation and gets its
name from its flat round
shape.
1414EX90
-------
FIELD USE
Portable radiation survey
instruments are calibrated
with laboratory sources
placed at various distances
from the detectors before the
site survey. A sampling grid
is established following data
quality objective goals. Once
the instruments are ready
and all health and safety
precautions have been
addressed by the field team,
the survey can begin. A
typical approach may consist
of two field personnel, one
with an alpha counter and the
other with a beta/gamma
(also known as Geiger)
counter. Each sampler would
have a log book in which to
record the readings at the
pre-ordained locations on the
grid. Due to the character of
gamma radiation, gamma
signals will be detected and
counted. It is important that
the sampler hold the counter
just above the ground surface
consistently through the
study. For screening pur-
poses, it is essential that any
radiation greater than back-
ground level be investigated
further to assure a thorough
knowledge of the radioactive
character of the site.
ADVANTAGES AND
LIMITATIONS
Commercially available
detectors are generally
reliable, consistent and easy
to use. The strong advan-
tage of knowing the radioac-
tive character of a hazardous
waste site is obvious. It
allows future characterization
and remediation to be
performed intelligently and
safely.
When combined with a
carefully planned laboratory
confirmation, field screening
can be a quick and effective
method for assessing the
extent and location of radio-
active contamination. Liquid
scintillation methods, alpha/
beta counting, alpha spec-
troscopy, and high resolution
gamma spectroscopic
methods can identify the
isotopes and better quantify
the radioactivity at the site.
Advantages
Limitations
• Rapid, real-time results
• Low cost (compared with
full laboratory analysis)
Easy to use
Inability to probe beneath
surface
Doesn't reveal specific
isotope identity
Difficulty detecting tritium
FUTURE WORK
A low-energy photon detector
system (LEPS) is being
investigated for use at mixed-
waste sites. Using germa-
nium diodes with a high
sensitivity to gamma-and x-
ray energies, this detector
can be encased in a water-
tight container and used
above ground or lowered into
a drilled borehole. This
technology promises remote
sensing of radiation by the
employment of rugged,
submersible detectors.
REFERENCES
Field Monitoring Standard Operating Procedures, U.S. EPA Field Monitoring Branch, #003
EMSL-ORS, 1990, 88 pp.
Moe, H. J., and E. J. Vallario, Operational Health Physics (particularly Chs. 10-12), ANL
publication #88-26, 1988, 930 pp.
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FOR FURTHER INFORMATION
For further details on field screening meth-
ods for radioactive contamination, contact:
Mr. Terry Grady
Nuclear Radiation Division
U.S. Environmental Protection Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas, Nevada 89193-3478
(702) 798-2136
FTS 545-2136
For general Technology Support information,
contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270/734-3207
FTS 545-2270
FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed and written by
Clare L Gertach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
f/EPA
Jr::sc ;"£:es
r-.vircnmentai Protection
Agency
zr-/i-crrer:ai Vcrrcrrc
3ys;err.s Laocratory
P O Box S3473
Las Vegas NV 89193-5J-73
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Internal Dosimetry
for Radionuclides
in Humans
INTRODUCTION
Monitoring human exposure
to radionuclides is an integral
component of EPA's mission
to protect the health of the
public. State-of-the-science
equipment and a rigorous
quality assurance program
provide scientists with
accurate information.
Whole body counting is an
internal dosimetry method
that uses gamma spectrom-
etry to identify radionuclides
and to measure their concen-
tration and distribution in a
human body.
Lung counting detects
inhaled radionuclides which
are deposited in the lungs.
Counting of areas of the body
such as the skull, the liver, or
other organs where specific
radionuclides may concen-
trate provides additional
information necessary to
calculate internal radiation
dose. The germanium
detectors used in both the
whole body and lung counter
are passive devices, i.e., they
detect emitted radiation but
do not emit any radiation
themselves.
Bioassay for tritium, stron-
tium, and other radionuclides
which are not detectable with
gamma spectroscopy is
performed, when necessary.
The Environmental Monitor-
ing Systems Laboratory-Las
Vegas (EMSL-LV) has
maintained a whole body
counting facility since 1966.
THE FACILITY AND
EQUIPMENT
Two counting vaults, shielded
with 6-inch thick, pre-World
War II steel walls, provide a
low background area for
counting. One vault, used for
whole body counting, is
equipped with a high purity
germanium detector posi-
tioned over an adjustable
chair in which the subject
reclines during the count.
High energy gamma-emitting
radionuclides, with energies
ranging from 60 keV to
2.0 MeV (such as cesium and
cobalt) can be identified and
measured with this system.
The second vault contains an
adjustable chair with six
state-of-the-art, high-purity
germanium semi-planar
detectors mounted above it.
These detectors, fitted with
very thin "windows" to admit
very low energy radiations,
are designed for detection of
low energy gamma and X-ray
emitting radionuclides (such
as americium and plutonium).
Detected energies range
from 10 to 300 keV. Lung,
liver, skull, and other specific
organ or bone counting is
done here.
Both counting vaults have
anticlaustrophobial mea-
sures. One wall of each vault
is covered with a mural to
provide a less institutional
feeling, and the subject may
watch TV or read.
Data acquisition and process-
ing equipment includes a
gamma spectroscopy system
which detects the radiation,
amplifies and shapes the
detector signals, stores and
displays data, and analyzes
the data to identify radionu-
clides. A fully-integrated
computer/multichannel
analyzer system is used, and
the software, including data
acquisition and analysis, data
base management, word
processing, and statistical
analysis, is tailored for whole
body counting needs.
0338EX91
-------
QUALITY
ASSURANCE
The efficiency of the detec-
tion system is determined by
comparing the amount of
radiation measured by the
counting system to the known
amount in a sample - in this
case, a polyethylene bottle
"phantom" called the
"BOMAB." Its shape and
volume is equal to a "stan-
dard man." Lung and thyroid
phantoms are also used for
efficiency calibration.
An energy calibration is done
daily to correct for the
inherent drift properties of
detectors.
Calibration results are
tracked with a quality assur-
ance software package.
Daily and monthly quality
assurance reports and plots
are generated. Internal and
external audits are routinely
conducted, and permanent
records are kept of quality
assurance and personnel
counting data. This facility
participates in intercalibration
studies with other whole boay
counting facilities in the
United States to check on
both efficiency and energy
calibration status.
COUNTING
PROGRAM
Civilian government, Depart-
ment of Defense, commercial
power plant, fuel fabrication
plant, and contractor person-
nel who have a potential for
exposure to radionuclides are
counted routinely. Any
person who feels they may
have been exposed to
radionuclides may make an
appointment for a count.
A program to assess levels of
radionuclides in members of
some of the families residing
in communities and ranches
surrounding the Nevada Test
Site was initiated in Decem-
ber 1970. The Community
Monitoring Station Network, a
joint endeavor among
Department of Energy,
Environmental Protection
Agency, and the Desert
Research Institute of the
University of Nevada, was
established in 1981. The
station managers of this
network, who are generally
science teachers in their
communities, and their
families, entered the counting
program at this time. The
families who participate in
this program are located in
Nevada, California, and Utah.
SUMMARY
The internal dosimetry
program and the networks
maintained by EMSL-LV
around the Nevada Test Site
and in the states west of the
Mississippi River provide for
the monitoring of human
exposure to radionuclides.
Whole body counting is
provided free of charge, by
appointment only, to EPA
Regional personnel and their
contractors who are involved
with radioactive or mixed
waste cleanup programs and
other work involving expo-
sure to radionuclides.
XC^°A/V
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FOR FURTHER INFORMATION
For further information on whole body counting, contact:
Ms. Anita Mullen
Health Physicist
Nuclear Radiation Division
U.S. Environmental Protection Agency
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2597
FTS 545-2597
For Technology Support Center information, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
Colorado Plateau
Pilot Study
ENVIRONMENTAL MONITORING
AND ASSESSMENT PROGRAM
Arid Ecosystems
The Environmental Monitoring and
Assessment Program
In 1988 the U.S. Environmental Protection Agency's
(EPA) Science Advisory Board recommended implement-
ing a nationwide program to monitor ecological status and
trends and to develop innovative methods for anticipating
emerging environmental problems before they become
widespread or irreversible. More recently, the EPA, in
cooperation with other federal agencies, research insti-
tutes, and university systems has initiated the Environmen-
tal Monitoring and Assessment Program (EMAP) as a
collaborative program to assess and document the condi-
tion of ecological resources at regional and national scales.
EMAP - Arid Ecosystems
To accomplish its goals and objectives, EMAP has
established eight ecosystem monitoring and research
groups (estuarine and marine, Great Lakes, surface waters,
wetlands, forests, agroecosystems, arid ecosystems and
landscape ecology) and seven cross-system program
groups (design and statistics, quality assurance, informa-
tion management, landscape characterization, indicators,
methods, and assessment). Arid ecosystems include
desertscrub, grassland, prairies, chaparral, open woodland,
riparian, and alpine tundra and are technically defined by
EMAP as terrestrial systems characterized by a climatic
regime where potential evapotranspiration exceeds
precipitation. Arid ecosystems in the United States
occupy nearly all the land surface area (excluding high-
elevation forests) west of the Mississippi River. Histori-
cally, dramatic urbanization and exploitation of natural
resources has resulted in rapid desertification, i.e., the
decline or loss of biotic productivity in arid, semi-arid and
any subhumid lands due to certain natural phenomena and
man-induced stresses. Once significantly degraded, arid
ecosystems are generally unlikely to return to their
preimpacted state and hence are often termed "fragile"
because they exhibit little resistance or resilience when
exposed to human-induced impact. Desertification, live-
stock grazing, biodiversity, water resource management,
air quality, and global climatic change have been identified
as regionally important issues in arid ecosystems.
The Colorado Plateau
The Colorado Plateau is characterized by a semi-arid
climate, sparse vegetation, and an abundance of exposed,
often brilliantly colored rock. The geological structure
consists of stacked plates of starkly beautiful layers of
sedimentary rocks which, although frequently altered by
uplifting, are generally flat, dipping only slightly
northward. These soft substrates have been deeply incised
by streams and rivers, resulting in canyons and rock
structures of awesome beauty and magnitude. This
process is especially displayed in southeastern Utah in the
Canyonlands and Arches National Parks. The driest and
lowest-elevation vegetation zone found throughout the
Colorado Plateau is composed of sagebrush, shadscale
blackbrush, and related desert shrubs. As the terrain
Gallup
f—
A
N
r
AZ NM o ' ' 120km
Colorado Plateau
August 1993
1198EX92
-------
increases in elevation, an extensive woodland made up
primarily of pinyon pine and juniper becomes dominant.
Even with a population of approximately 1 million, the
Colorado Plateau still remains a remote region of undis-
covered and forgotten places. The traditional economic
base has been ranching and mining with limited farming
and logging. More than one quarter of the region's
residents are employed in services related to tourism,
recreation, and retirement. Approximately 85 percent of
the Colorado Plateau is government owned or maintained.
Six percent is state owned and the remainder is under
federal jurisdiction. The Bureau of Land Management
(BLM) is the largest government land manager in the
region, responsible for 29 percent of the land. Indian tribal
lands encompass 23 percent and the U.S. Forest Service
(USFS) is responsible for 22 percent. The National Park
Service (NPS) manages only 4 percent of the region, yet
the 26 Park Service units attract over 30 million visitors
per year. As is often the case in these rugged landscapes,
permanent residents and visitors are concentrated in less
than 5 percent of the available land space. Although most
of the lands of the Colorado Plateau remain relatively
unchanged by direct human contact, recent growth in
human populations and changes in land management
practices are likely to result in changes in ecological
condition throughout the Plateau. For instance, NPS has
recently measured visibility impacts from air pollution
associated with coal-fired power generating stations at
some of its remote sampling sites.
The Colorado Plateau Pilot Study
The southeastern Utah region of the Colorado Plateau has
been selected as the site for the EMAP-Arid Ecosystems
1992 and 1993 pilot studies. The pilot studies will serve to
test three categories of indicators for arid ecosystem
condition (spectral properties; vegetation composition,
structure, and abundance; and soil productivity). The
purpose of these studies will be to focus on answering
important questions on indicator performance, such as
determining components of variance and sample plot
design, rather than providing a regional estimate of
condition or extent. Other important information related to
methods development, logistical requirements, data
management, and quality assurance will also be deter-
mined from these types of studies. Results from the pilot
studies will be used to develop a regional demonstration
project over the entire Colorado Plateau in 1995. The
EMAP-Arid group has chosen to test its indicators in three
of the arid ecosystem biomes—desertscrub, grassland, and
woodland, which are compositionally and structurally very
dissimilar.
These pilot studies will provide the background informa-
tion that is necessary for future, in-depth studies of arid
ecosystems.
EMAP-Arid Sampling Design
The EMAP-Arid sampling design uses a systematic
triangular grid that can be extended to a global network.
Each point is equidistant (27.1 km) from its neighbor
which results in the placement of equal area hexagons of
640 km2 providing for uniform spatial coverage. Thus, the
base grid density creates an equal sampling support area
which results in a pattern of 12,600 regularly placed points
in the 48 conterminous states. The spacing of the grid will
allow sampling of ecological resources to provide statisti-
cally unbiased estimates of status, extent, and trend with
quantifiable confidence limits over regional and national
scales.
The sampling points selected for the pilot studies are
located in a variety of ownership regimes, terrains, and
elevations. Some of the points are located within
Canyonlands National Park, Glen Canyon National
Recreation Area, Manti La Sal National Forest, and the
Navajo Tribal Nation.
Pilot Field Activities
The sampling points will be sampled between June and
August, of 1992 and August and September of 1993. Field
sample teams will be staffed by a soil scientist, botanists,
and field technicians. The EMAP-Arid field crews will be
trained and qualified personnel selected from the perma-
nent staff of the BLM, NPS, USFS, EPA, and the Soil
Conservation Service (SCS).
Additional information relative to the EMAP-Arid Pilot
Study on the Colorado Plateau can be obtained by writing
to:
William G. Kepner
EMAP - Arid Ecosystems Technical Director
U.S. Environmental Protection Agency
P.O. Box 93478
Las Vegas, Nevada 89193-3478
-------
United States Environmental Monitoring October 1993
Environmental Protection Systems Laboratory
Agency P.O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT TECHNOLOGY SUPPORT PROJECT
SERA EMAP -
Ecosystems
Introduction
The Spectral
Indicator
sponse to environmen-
tal stress which is an
indicator of plant condi-
tion (process and
function). Spectral
measurements may be
made at different time
intervals allowing
analysts to monitor
environmental condition
and change. Spectral •
measurements of the
same area on the
(continued on next page)
The U.S. EPA is col-
laborating with universi-
ties, states, private
research groups, and
other federal agencies
to research, monitor,
and assess the condi-
tion of the ecological
resources of the nation.
The Environmental
Monitoring and Assess-
ment Program (EMAP)
is designed to identify
trends in the ecological
condition of natural
resources.
EMAP-Arid is studying
the condition of areas
generally having low
annual precipitation.
Approaches for moni-
toring arid ecosystems
span the disciplines of
meteorology, soil
science, plant and
animal ecology, and
remote sensing.
The 1992 EMAP-Arid
Ecosystems Pilot in
southeast Utah was
designed to test meth-
ods of measuring
vegetation condition,
soil properties, and the
spectral values of
vegetation and soils.
Spectral measurements
use electromagnetic
radiation to provide
information about the
physical and chemical
properties of materials.
Natural objects exhibit
specific spectral curves
that permit the charac-
terization and discrimi-
nation of their physical,
chemical, and biological
states. The spectra of
vegetation can be used
to detect shifts in
photosynthetic re-
1071EX9300C
-------
Introduction
(continued)
earth's surface are
collected every 16 days
by Landsat satellites at
a scale of 30 x 30 m for
the Thematic Mapper
(TM) system, and 80 x
80 m for the Multispec-
tral Scanner (MSS). In
addition, the NOAA
Advanced Very High
Resolution Radiometer
(AVHRR) collects data
twice daily at 1.1 x 1.1
km resolution. The data
are collected as bright-
ness values at specific
intervals along the
electromagnetic spec-
trum. Satellite data of
this type may be directly
comparable with finer
scale spectra obtained
by a portable field
spectrometer and with
vegetation and soil
properties measured by
traditional field tech-
niques. Figure 1
illustrates spectral
60 -i
curves within the visible
and near-infrared part
of the spectrum of three
cover types; healthly
green vegetation, red
soils, and clear water.
P 40 -
8 20
IE
400
—I—
500
—r
600
—I—
700
—I—
800
900
1000
WAVELENGTH (nm)
Figure 1. Typical spectra of vegetation, red soil, and
water.
Purpose of
Spectral
Indicator
The purpose of this
research is to develop a
comprehensive indica-
tor of ecological condi-
tion which integrates
vegetation and soil
characteristics and can
be applied across a
region for all natural
resource classes. A
remote sensing ap-
proach offers a number
of advantages to
indicator research
development such as
producing spatially
explicit estimates of
ecological condition
over entire regions in a
cost effective manner
and reducing physical
disturbance associated
with field data collec-
tion. Researchers have
developed strong
correlations between
remote sensing -
derived measurements
(and indices) and
ecosystem variables.
One such index is the
Normalized Difference
Vegetation Index
(NDVI) which is being
tested as the spectral
indicator. NDVI is a
simple relationship
involving reflected red
radiation and near
infrared radiation. In
general, healthy green
vegetation absorbs
energy in the red region
of the electromagnetic
spectrum and is highly
reflective in the near-
infrared region. Re-
searchers have shown
strong correlation
between NDVI derived
from satellite and
ground measurements
and Leaf Area Index.
The Leaf Area Index
correlates very highly
with a number of other
extremely important
ecosystem variables
such as primary pro-
ductivity and biomass
and, therefore, changes
in NDVI values may be
used as an indicator of
ecosystem status.
The focus of research
on the spectral indicator
within the EMAP-Arid
pilot are:
1. Compare satellite
measurements from
Landsat Thematic
Mapper (TM), Multi-
spectral Scanner
(MSS) and Advanced
Very High Resolution
Radiometer
(AVHRR) to ground
vegetation and soil
properties in order to
extrapolate condition
of vegetation and
soils on a regional
scale.
2. Compare satellite
measurements to
ground spectral
measurements to
assess spectral
variability at multiple
scales.
3. Compare ground
spectral measure-
ments to conven-
tional ground vegeta-
tion and soils mea-
surements to assess
spectral variability at
a field plot level.
-------
Evaluation of
Spectral
Indicator
Analysis and
Discussion
During the summer of
1992, EMAP-Arid
scientists conducted
field work in southeast
Utah as part of an
indicator pilot study
designed to answer
important questions on
indicator performance,
such as determining
components of variance
for vegetation, soil, and
spectral measure-
ments. Spectral mea-
surements were made
within the context of a
sampling strategy
integrated with the
other two sets of indica-
tors. Plot design for the
EMAP-Arid pilot con-
sisted of six transects,
40m in length, radiating
from a center point with
three radial and three
external segments
resulting in a hexagon
shaped plot encom-
passing about one
hectare. Circular
subplots, 7 m in diam-
eter were located at the
center point and at the
end of each transect.
Eighteen spectral
measurements were
made along each of the
six sampling transects.
They were taken 50cm
from the transect and
clustered in groups of
three, coincident with
vegetation samples
(i.e., at 3.5,4, 4.5, 9.5,
10,10.5m, etc.) In
addition, a 9m square
grid having a 4 x 4
matrix, with sampling
points at 3m intervals,
was centered within
each of the seven
circular subplots.
Spectral measurements
were taken at 16 points
in each grid, resulting in
a total of 220 measure-
ments. Measurements
were recorded at each
of 15 different locations
in southeast Utah.
Ground-based spectral
measurements are best
made between 10:00
am and 2:00 pm, when
the sun angle is high
and shadows are mini-
mal. Spectra cannot be
acquired when the sun is
obscured by clouds, or
when cloud cover ex-
ceeds 50 percent. The
measurements were
made with a Personal
Spectrometer II (PS-II), a
portable, lightweight
instrument designed to
acquire a suite of spec-
tral measurements in the
visible and near infrared
part of the spectrum.
The measurements were
made between late June
and late August. On
August 20, Landsat 5
acquired both TM and
MSS imagery over the
same area. These two
sets of spectral data are
being analyzed to pro-
duce satellite-based
values for NDVI, and to
ascertain ground surface
physical characteristics.
The spectral data
acquired in Utah are
currently being ana-
lyzed for the purpose of
relating the spectral
measurements to soils
and vegetation param-
eters. Figure 2 shows
how remotely derived
information produce
different spectral
curves, that allow
discrimination of spec-
tra relating to plant
condition. The differ-
ence of spectral curves
relate impairment or
shifting of photosyn-
thetic activity related to
environmental stress,
such as available
moisture. Statistical
measurements estimat-
ing the spectral variabil-
ity of each sample site
and between sample
60 -i
UJ
0
1
§
u.
Ill
I
40 -
20 -
sites will be made. The
spectral data will be
further compared with
(continued on next
page)
LESS MOISTURE STRESS
GREATER MOISTURE STRESS
400
-r~
500
600
I
700
-r-
800
-I-
900
l
1000
WAVELENGTH (nm)
Figure 2. Difference in spectra related to moisture
stress in an arid woodland.
-------
Analysis and
Discussion
(continued)
the AVHRR and
Landsat TM and MSS
data acquired for the
same areas to deter-
mine if satellite imagery
of different spatial
resolution can discrimi-
nate the condition of
vegetation and soil
parameters on a re-
gional scale. For
instance, if AVHRR is
representative of the
parameters considered,
then it becomes a
preferred imagery due
to its economy of
temporal frequency and
expense.
Experiments will be
conducted during 1993
to ascertain how many
ground-based spectral
measurements are
necessary to correlate
traditionally measured
vegetation and soil
parameters with satel-
lite data. It is antici-
pated that this will vary
depending upon the
vegetation type and
biogeographic region.
Seasonal and diurnal
variability in field spec-
tra will also be investi-
gated, in order to
improve the level of
confidence resulting
from interpretations of
field data. Values for
the NDVI spectral
indicator have been
calculated at field plot
and regional levels, and
at present it is uncertain
how sensitive the
indicator will be to
changing environmental
conditions. The setting
of threshold limits
between condition
classes, i.e., accept-
able, marginal, and
unacceptable, is a
critical issue reserved
for future research in
the development of the
spectral indicator.
Results from the spec-
tral portion of the
EMAP-Arid ecosystem
pilot study will help
EMAP-Arid determine
the utility of such
indicators within its
overall program. This
research will benefit not
only EMAP-Arid, but
other EMAP resource
groups and their col-
laborators.
For further Information, contact:
William G. Kepner
EMAP-Arid Technical
Director
U.S. EPA
P.O. Box 93478
Las Vegas, NV
89193-3478
David A. Mouat
EMAP-Arid Spectral
Indicator Leader
Desert Research
Institute
University of Nevada
System
P.O. Box 60220
Reno, NV 89506-0220
Robert P. Breckenridge
EMAP-Arid Indicator
Coordinator
Idaho National
Engineering Laboratory
EG&G - Idaho, Inc.
P.O. Box 1625
Idaho Falls, ID
83415-2213
xg*'0*v
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For information about the Technology Support Center at EMSL-LV, contact:
Mr. Ken Brown
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed by Clare L Gerlach,
Lockheed Environmental Systems & Technologies Company, Las Vegas
-------
&EPA
INTRODUCTION
BACKGROUND
Unitec States tnvironmentai Monitoring
Environmental Protection Systems Laboratory
Agency P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT
Immunochemistry
for Environmental
Monitoring
The Environmental Monitoring
Systems Laboratory - Las
Vegas (EMSL-LV) is pioneer-
ing an investigation into the
usefulness of several immuno-
chemical techniques for
monitoring the extent of
contamination in various
environmental and biological
matrices. Immunochemistry
includes all methods of sample
preparation and analysis that
incorporate antibodies that
have been developed for
specific analytes or groups of
analytes. Enzyme-based
immunochemical techniques
have been in use since the
'70s and more recent efforts
have focused on their appli-
cability to the complex
matrices that face environ-
mental scientists. The
EMSL-LV has developed and
demonstrated several
immunochemical techniques
and believes that these
methods hold great promise
Ncve~cer ' =5'
TECHNOLOGY SUPPORT PBD.ifpt
for the quantitative analysis
of target analytes for use in
ground-water surveillance,
in situ hazardous waste site
monitoring, and assessment
of human exposure. Current
work involves the analysis of
chemicals, like PCBs,
nitroaromatics, and certain
pesticides, that are difficult to
analyze by other analytical
methods.
Immunochemistry includes
techniques such as
immunoaffinity and immuno-
assay. Immunoaffinity is a
sample preparation proce-
dure that takes advantage of
the attraction between an
antibody and a specific
analyte. Immunoaffinity
preparations have great
potential for cleanup of
complex samples like dioxins.
By rinsing a sample over an
antibody-treated surface,
scientists can isolate particu-
lar compounds in the sample
that adhere to the antibody.
The isolated compound is
then eluted from the immobi-
lized antibody and is ready
for analysis by chromatogra-
phy or immunoassay. One
common immunoassay is the
enzyme-linked immuno-
sorbent assay (ELISA). The
specificity of the antibody for
the analyle and the resultant
immune complex is the basis
for the specificity of immuno-
assays. Most field immuno-
assays are colorimetric
analytical methods that
quantify compounds of
interest. A sample is spiked
with a known amount of a
labelled analyte. The label is
typically an enzyme. A
chromogenic substrate is
added to serve as an
indicator of compound
concentration in the sample.
Laboratory-based immuno-
assays include fluorescent
and radioactive methods that
have greater sensitivity but
are less portable.
FIELD USE
Immunoassays are portable,
rugged, and inexpensive.
Their use at hazardous waste
sites has been investigated by
the EMSL-LV. The results of
Superfund Innovative Tech-
nology Evaluation (SITE)
studies indicate a strong
correlation between field
immunoassays, laboratory
immunoassays, and gas
chromatography/mass
spectrometry. The only
equipment needed is a
spectrophotometer, various
microtiter plates or test tubes,
precision pipets, and immuno-
logic reagents. The 96-well
microtiter plate is approxi-
mately 3" x 6" and has 96
depressions, each capable of
holding about 250 ^L liquid.
Smaller microtiter strips are
available that can be as-
sembled to form modular
sections for individual
analytes. These plates and
test tubes are available pre-
coated with the antibody
base.
Another field use of immuno-
chemistry is being explored
at the EMSL-LV. This use
may revolutionize safety and
exposure precautions used
by workers who deal with
hazardous chemicals. Dosi-
meter badges with an immu-
nochemical twist are available
for pentachlorophenol and
nitroaromatics. These
personal exposure monitors
(PEMs) are lightweight,
inexpensive, can be analyzed
quickly, and provide real time
indication of exposure. These
badges employ a micro-
dialysis tubing containing an
immobilized antibody phase.
Immediate identification of
high exposure levels is critical
to the conduct of safe site
characterization.
1146EX91
-------
ADVANTAGES AND
LIMITATIONS
The use of immunochemical
techniques is gaining accep-
tance in the area of environ-
mental science. One need
that is being addressed is
that of specificity. Fre-
quently, immunoassays are
available for a class, like
PCBs. Specific quantitation
for each component would be
difficult.
PEMs are available for
pentachlorophenol and are
being developed for para-
thion and chlorpyrifos. The
development of PEMs must
address the question of
Advantages
Limitations
Field portable
User friendly
Quick and inexpensive
Potential for wide range of
analytes
Useful for many matrices
Low detection limits
Separate immunoassay
needed for each analyte
More complex analysis
required for quantitation of
specific analytes
Long development time
for new antibodies and
methods
diffusion of chemicals
through the dialysis tubing,
the optimum concentration of
the antibody, detection limits
and quantitation of the
badge, the efficiency of the
antibody in capturing the
analyte, and the capacity of
the device.
FUTURE
The EMSL-LV is active in the
development of all immuno-
chemical methods that have
potential for Agency use.
One new avenue of investiga-
tion is the use of antibody-
coated fiber optic immuno-
sensors. Another application
is the integration of robotics
capability for high sample
throughput and a tiered
analytical approach, i.e.,
biological and environmental
samples, biomarkers, target
analytes, and degradation
products. This system of
analytical procedures will
enable scientists to measure
contamination at the source,
follow the fate and transport
of residual amounts, and
assess human exposure.
Multi-analyte immunoassays
that can identify several
analytes simultaneously are
expected to expand the
desirability of immunoassay
technology for environmental
use. Work in this area is
already underway at the
EMSL-LV.
REFERENCE
Immunochemical Methods for Environmental Analysis, J. M. Van Emon and Mumma, R. O.,
eds., ACS Symposium Series 442, ACS, Washington, DC, 1990,229pp
^ -r %-
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roject
UX3YS
/
FOR FURTHER INFORMATION
For further information about immunochemistry for environmental monitoring, contact:
Dr. Jeanette Van Emon
Exposure Assessment Research Division
Environmental Monitoring Systems Laboratory - Las Vegas
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2154
FTS 545-2154
FAX (702)798-2243
For information about the Technology Support Center at EMSL-LV, contact:
Mr. Ken Brown
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory - Las Vegas
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
SEPA
Jnitec states
Environmental Protection
Agency
Environmental Mcniicrng
Systems Laccratory
p'O. Box 53478
Las Vegas NV 89193-347
Jine ' 1
OFFICE OF RESEARCH AND DEVELOPMENT
High Resolution
Mass
Spectrometry
TECHNOLOGY SUPPORT PROJECT
INTRODUCTION
The identification and
quantitation of organic
compounds is a fundamental
goal of both CERCLA and
RCRA. When the identity of
the organic compound is
known, the formal CLP
methods are generally able to
address the quantitation
needs. Often, however, the
exact identity of an organic
contaminant is not obvious
and is intractable to the
commonly used low resolu-
tion mass spectrometer. In
these cases, a little chemical
detective work is needed!
Many thousands of pollutants
exist, but only a few hundred
matching standards are
available, predominantly for
the Target Compound List
(TCL) pollutants. High
resolution mass spectrom-
eters (HRMS) have been
developed to provide a closer
reading of the fingerprint of a
molecule or element. With
HRMS it is possible to isolate
specific characteristic ions,
determine their accurate
mass, and thus assign the
correct elemental composi-
tion without reference stan-
dards. Thus, HRMS is a
valuable tool for structure
determination, and has
largely replaced other
techniques such as elemental
analysis for structure verifica-
tion. Data interpretation is
complex, as is the instrumen-
tation. Expert analysts must
combine their knowledge of
chemical interactions with
super-sleuthing capabilities to
effect a complete and suc-
cessful identification. The
Environmental Monitoring
Systems Laboratory-Las
Vegas has the analytical
expertise and instrumentation
necessary to provide an-
swers to the most difficult
problems of environmental
analysis.
INSTRUMENTATION
Mass spectrometry is a three-
phase analytical procedure
consisting of ionization,
separation, and detection.
High resolution mass spec-
trometry differs from other
techniques primarily in the
separation capability. High
resolution instruments are
able to separate ions having
the same nominal mass but
differing in specific elemental
composition and hence in
accurate mass, because
each element varies from
integral mass slightly and
differently (except carbon, set
at 12.0000). HRMS has
been applied to organic and
inorganic identification at
ultratrace levels. For ex-
ample, minor organic con-
taminants, rare earth ele-
ments, and lead isotope
ratios can be identified and
used for site-specific finger-
printing. The high resolution
instrument is much larger and
more expensive than the
commonly used quadrupole
mass spectrometer. It
contains a large magnet and
an electrostatic sector to
provide a focused beam of
ions for determinations of
mass that are accurate to
1/1000 of a mass unit. This
ability to separate com-
pounds having the same
integer mass number is a
great advantage to the
analyst who is faced with a
particularly difficult mass
assignment. High resolution
mass spectrometers are
equipped with special inlet,
ionization, and computer
systems to maximize their
capabilities.
0071EX91
-------
The interpretation of high
resolution mass spectral data
is a complex procedure. A
skillful and experienced
spectroscopist incorporates
several areas of expertise
into a thoughtful reading of
the experimental data. The
analyst uses historical
information about the site and
its contamination, early
results from low resolution
mass spectrometry, knowl-
edge of the probable chemi-
cal reactions, precursors, by-
products, and experience in
recognizing the statistical
significance of a measure-
ment that borders between
two interpretations. Some-
times the particular compo-
nent of interest has been
depleted or altered by
biodegradation,
photodegradation, or another
agent. The mass spectral
analysis must then be
thoughtfully focused upon
chemical precursors or by-
products of the original
compound.
The complexity of high
resolution mass spectrometry
interpretation demands
considerable interpretive
expertise. This level of effort
is justified for identification of
unknown toxic contaminants
during site characterization
and remediation. It can also
allow the unambiguous
correlation of off-site contami-
nation to a specific site.
REFERENCES
The Wiley/NBS Registry of Mass Spectral Data, F. W. McLafferty and D. B. Stauffer, eds., 1989.
Interpretation of Mass Spectra, 3rd Edition, F. W. McLafferty, University Science Books, 1980.
FOR FURTHER INFORMATION
The EMSL-LV will support the Regions in the determination of the identity of compounds that
are intractable to routine analysis. This assistance can aid in the identification of the Poten-
tially Responsible Party (PRP).
Advantages
Dependable, high sensitiv-
ity detection
Legally defensible
determinations
Ability to identify prevl-
ously unlisted compounds
Site fingerprinting
Limitations
Costly Instrumentation
Expert Interpretation Is
needed
For more information about specialized mass
spectrometry services available at EMSL-LV
through the Technology Support Center,
contact:
Dr. Wayne Sovocool
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, Nevada 89193-3478
(702) 798-2212
FTS 545-2212
For information about the Technology Support
Center at EMSL-L V, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
SEPA
-r,;ea 5ia:es
Erviromentai Protection
Agency
E". rzr<~s~:a' Mcriicrrg
S/sie^s LaDcrator/
P O 3ox 93478
Las Vegas NV 89193-3473
AuC-s;
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Open Path FT-IR Use in
Environmental Monitoring
'//
INTRODUCTION
INSTRUMENTATION
A major environmental
concern is the identification,
location, and extent of volatile
organic compound (VOC)
contamination in the air at
hazardous waste sites. Open
path (or long path) FT-IR was
adapted to environmental use
to address the need for
information about VOC levels
and to improve upon costlier
and more time-consuming
current methods. Open path
FT-IR is useful at many
stages of screening and
remediation because VOC
contamination can result from
many sources, including
underground storage tank
leaks, chemical spills, and off-
gassing at air stripping plants.
A mobile system has been
developed at Kansas State
University through a coopera-
tive agreement with EMSL-LV
and Region 7. The mobile
laboratory set-up provides an
on-site, quick turnaround
means of obtaining data that
can guide remediation deci-
sions. The outlook for ex-
panded use of open path
FT-IR is excellent, with re-
search in the area responding
to the needs of field scientists
and Agency personnel.
The FT-IR spectrometer
being used for developmental
work is a Bomem DA02
system equipped with a KBr/
Ge beam splitter, a mercury-
cadmium-telluride detector
that is liquid nitrogen cooled,
an adjustable tripod, and a
collection telescope (10-inch
Cassegrainian). The source
is an air cooled and quartz
shielded Nernst glower
operating at 2,000 Kelvin.
This source is located at the
focal point of a 20-inch
Newtonian telescope in order
to generate a collimated
beam of infrared radiation.
The mobile laboratory is
driven to one side of the site
to be surveyed and the FT-IR
spectrometer with its collec-
tion telescope is set up
adjacent to the station. The
IR source and its collimating
telescope are positioned on
the opposite side of the site
to be surveyed so that the
collimated beam of infrared
radiation may be sent across
to the collection telescope of
the FT-IR spectrometer. A
laboratory calibration is
usually sufficient for field
sampling.
An alternative arrangement is
to place both the source and
the spectrometer adjacent to
the laboratory station. Then a
reflector is placed on the
opposite side of the site so
the collimated beam of
infrared radiation is sent
across the site to the reflector
and bounced back to the
spectrometer. In either
arrangement, the IR absorp-
tion spectrum of the atmo-
sphere above the site is used
to identify any VOC present in
the path of the beam.
SCOPE
Open path FT-IR is useful for
the qualitative and quantita-
tive measurement of VOC
and low-boiling semivolatile
compounds. To date, the
spectral database contains
35 VOC files, with a total of
70 compounds expected to
be included by the end of
1990. The instruments can
be positioned at varying
heights above the soil by
using tripods. Though this
technology is sensitive to
meteorological factors such
as wind, particulate matter,
and rain, most of these
affect point sampling by
canister as well. Open path
FT-IR is faster and cheaper
than the canister methods
while providing a greater
likelihood of locating the
pollutant plume and should be
the favored technique when
time and budgetary con-
straints are considerations.
1323EX90
-------
ADVANTAGES AND
LIMITATIONS
Using open path FT-IR to
analyze the atmospheric
concentration of VOC and
solvents is a newly developed
and emerging technology. It
has many advantages and
some limitations that are
presented here as an aid to
methodology decision-making.
It is obvious that the Data
Quality Objectives (DQO) of a
site must drive the decisions
Advantages
Low analysis cost
Computerized operation
Rapid results
Limitations
In development stage
Equipment is customized
Sensitive to meteorological changes
Provides average concentration along pathway
on instrumentation so that the
necessary data are not
compromised. As with any
new method, specialized
equipment and expert advice
is fundamental to the site-
specific applicability of the
technique.
FUTURE PLANS
As open path FT-IR gains
stature as an environmental
screening tpol, work will be
underway to refine its capa-
bilities in quantitation. A
growing database that will
include more VOC and some
semivolatile compounds will
increase the usefulness of
this method. The anticipated
demand for instrumentation
will result in the development
of more sensitive, integrated
systems. Better computer-
ized formats may enable
extrapolation from atmo-
spheric to subsurface con-
centration. The first two
limitations listed above are
not intrinsic to the method
and will be solved with the
advent of commercially
available systems. In general,
the outlook is very positive for
increased need for screening
technologies such as FT-IR
and the demand is expected
to guide researchers to
promising refinements of
these techniques.
REFERENCES
Fateley, W. G., R. M. Hammaker, D. F. Gurka, Field Demonstration for Mobile FT-IR for
Detection of Volatile Organic Chemicals, EPA Report 600/4-90/008, March 1990.
Spartz, M. L., M. R. Witkowski, J. H. Fateley, J. M. Jarvis, J. S. White, J. V. Paukstelis,
R. M. Hammaker, W. G. Fateley, R. E. Carter, M. Thomas, D. D. Lane, G. A. Marotz,
B. J. Fairless, T. Holloway, J. L. Hudson, and D. F. Gurka, Evaluation of a Mobile FT-IR
System for Rapid VOC Determination, Part 1: Preliminary Qualitative and Quantitative Calibra-
tion Results, Am. Envir. Laboratory, November 1989, pp 15-30.
FOR FURTHER INFORMATION
For further information about Open Path FT-IR, contact:
Dr. Don Gurka
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2312
FTS 545-2312
xg^°a/.
^ T %
^ I echnology %¦
° C * z
O ^upport Q
'ik Project £
V/
For information about the Technology Support Center, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
FAX/FTS 545-2637
The Technology Support Center fact sheet series is developed and written by
Clare L Geriach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
*>EPA
wPitea states
environmental Protection
Agency
E"v rcr'-ertai V1cr,tcr'-g
Systems ..accratory
? O. Box 93*178
Las Vegas NV 39193-3478
. jv ' 35'
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Continuous
Monitoring with
Purge-and-Trap
Gas
Chromatography
Final
Report
INTRODUCTION
Preliminary site assessment
and monitoring of remedia-
tion efforts rely upon timely
and accurate information.
Various methods exist for the
continuous monitoring of
water and air samples, their
value lies in the elimination of
labor-intensive sample
collection, handling, and
analytical procedures. The
generation of real-time data
permits treatment systems to
operate in a true process
control mode. Additionally,
data quality may be better
since samples are never
subjected to the packaging
and transport needed for
conventional laboratory
analysis.
The Environmental Monitor-
ing Systems Laboratory - Las
Vegas (EMSL-LV) is inter-
ested in the application of
continuous monitoring
technologies that will reduce
the time-in-field for environ-
mental scientists working at
Superfund and RCRA sites.
A system developed by
Analytic and Remedial
Technology, Inc. was evalu-
ated for the on-line monitoring
of volatile organic compounds
(VOCs) in a ground-water
treatment process. This
monitoring system, Automated
Volatile Organic Analytical
System (AVOAS), consists of
a sampling manifold, a purge-
and-trap unit coupled to a gas
chromatograph (GC)
equipped with an electrolytic
conductivity (or Hall) detector
and a computer system. The
innovative components of this
system are:
(1) the sampling manifold,
which allows for direct,
on-line intake of samples
from different collection
points or treatment
streams.
(2) the injector, which allows
direct injection of the
sample into the GC
without the handling and
preparation steps often
associated with VOC loss
due to volatilization.
(3) the computer software
that is customized for the
analysis system.
The AVOAS was tested at a
Superfund site in Region 1
under the Superfund Innova-
tive Technology Evaluation
(SITE) program. Under the
conditions of this study, the
EMSL-LV found this system
to be reliable and easy to
use. Comparisons of data
from the AVOAS study with
standard analytical laboratory
results from sample splits
indicate a strong correlation.
The AVOAS results were
consistently higher, perhaps
reflecting differences due to
sample loss during transport.
DEMONSTRATION
The evaluation was con-
ducted at the Wells G&H Site
in Woburn, MA, U.S. EPA
Region 1. Ground water at
the site is known to be
contaminated with VOCs.
Remedial action required
treatment of the ground water
to remove the VOC contami-
nation. As a result, a pilot-
scale operation of a ground-
water extraction and treat-
ment system was conducted
to evaluate the relative merits
of three treatment processes:
an ultraviolet/chemical
oxidation process, a carbon
adsorption process, and an
experimental dehalogenation
process.
Six sampling points in the
"treatment train" were se-
lected to monitor the effi-
ciency of the individual
methods for reducing VOC
content. These discrete
samples were sent off-site for
standard analyses using a
purge and trap GC/MS
(Continued)
0697EX91
-------
method. This treatment
study presented an excellent
opportunity to demonstrate
and evaluate the AVOAS as
an application of the prin-
ciples of process analytical
chemistry during a remedia-
tion activity. The AVOAS
was programmed to collect
and analyze samples at six
collection points. In addition
to the GC/MS samples,
matching samples were
taken and shipped to the
EMSL-LV for analysis by
EPA GC Method 502.2. The
AVOAS GC analysis is similar
to Method 502.2, making
direct comparison allowable.
A variety of QA/QC samples
were also analyzed under
each protocol, consistent with
the requirements of the study
design.
The use of continuous
monitoring devices holds
great promise for enhancing
the characterization and
remediation activities at a
hazardous waste site. The
increasing number of these
devices coming into the
environmental market puts a
burden of evaluation upon
both manufacturer and
consumer. There is no gain
in sacrificing data reliability
for ease of use. The EMSL-
LV will continue to evaluate
the performance of demon-
strated technologies, like the
AVOAS, for applications
where a need is indicated.
Advantages
Limitations
Eliminates problems
associated with
standard VOC
sampling and
transport
Allows selection of
sampling point,
frequency, intervals
Reduces labor costs
Provides real-time,
in-situ data
Minimizes exposure
of field personnel
Initial hardware cost
Problems associated
with long-term operation
need to be identified
Availability of equipment
Application to other
situations must be
explored
REFERENCES
Volatile Organic Compounds in Water by Purge and Trap Capillary Column Gas Chromatogra-
phy with Photoionization and Electrolytic Conductivity Detectors in Series, Method 502.2, U.S.
EPA, Cincinnati, 1986.
Methods for the Determination of Organic Compounds in Water, U.S. EPA, Office of Research
and Development, Cincinnati, 1986.
FOR FURTHER INFORMATION
For more information about this study and how continuous monitoring of ground water may
help you, contact:
Dr. Stephen Billets
Quality Assurance and Methods Development Branch
Environmental Monitoring Systems Laboratory
Las Vegas, NV
(702) 798-2232, (FTS) 545-2232
For information about the Technology Support Center at EMSL-L V, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
&EPA
INTRODUCTION
Umtec Slates
EnvironmentaJ Protection
Agency
Environmental Monitoring
Systems laooratory
P.O Box 93478
Las Vegas NV 89193-3478
Ncvemcer ' SSI
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
UV-Vis Lumines-
cence in Field
Screening and
Monitoring
100 ppb
350 400 450
Wavelength (nm)
Ultraviolet-visible
photoluminescence tech-
niques (including fluores-
cence and phosphorescence)
are gaining recognition as
useful methods for monitoring
Superfund, RCRA, and other
hazardous waste sites. The
Environmental Monitoring
Systems Laboratory - Las
Vegas (EMSL-LV) is active in
the research, development,
and application of these
methods. This document will
focus on fluorescence
spectroscopy. One applica-
tion of this method uses a
fixed wavelength excitation
and records the fluorescence
emission spectrum of the
sample. Another application,
synchronous fluorescence
spectroscopy scans both
excitation and emission
monochromators to produce
a simplified spectrum,
typically with one peak per
compound. This allows
polyaromatic hydrocarbons
(PAHs) to be separated
roughly into classes accord-
ing to the number of fused
rings. Both techniques hold
great promise as field meth-
ods that are suitable to the
screening, characterization,
and monitoring of contami-
nants at hazardous waste
sites. Although mostly used
for PAHs, phenols, and
pesticides, luminescence
techniques are also available
for metal chelates and
uranium.
With the emergence of field-
deployable, field-portable
instruments, and fluores-
cence sensors, luminescence
spectroscopy is joining the
list of easy-to-use, inexpen-
sive methods for evaluation
of contamination at hazard-
ous waste sites.
INSTRUMENTATION
FIELD USE
Luminescence techniques
are mostly used for the
analysis of aqueous samples,
though soil extracts may also
be used. The most fre-
quently used source is a
pulsed or continuous xenon
lamp which disperses light
through a grating. Alternative
light sources include mercury
lamps and lasers with either
fixed or tunable wavelengths.
For scanning spectrofluorom-
eters, the continuous spec-
trum of the light source is
dispersed by an excitation
monochromator, which can
be scanned mechanically to
select a bandpass. Then, the
emitted light at each wave-
length is detected (usually at
right angles to the exciting
light) by an emission mono-
chromator coupled to a
detector. For quantification,
the fluorescence intensity is
compared to the response
from standards at various
levels on a calibration curve.
Identification, classification,
and quantification can be
performed by either fluores-
cence emission or synchro-
nous fluorescence spectros-
copy. The generated spectra
are simplified cross-sections
of excitation-emission arrays.
Both emission and synchro-
nous luminescence methods
are useful for characterizing
the source and concentration
of various polyaromatic
compounds. Current work on
PCBs and PAHs demon-
strates the usefulness and
sensitivity of luminescence
methods.
The applicability of lumines-
cence methods to environ-
mental work is increasing
with greater availability of
compact instruments. The
EMSL-LV has field-
deployable fluorescence
instruments. In addition, a
prototype of a portable
synchronous spectrofluorom-
eter with a fiber optic probe is
being developed for the
EMSL-LV through an
interagency agreement with
the DOE at Oak Ridge
National Laboratory. Using
these instruments, scientists
are able to identify and
quantify total PAHs and
PCBs. These methods are
particularly good for environ-
mental samples requiring
relatively simple sample
preparation. Field use is
(Continued)
1185EX91
-------
simple for this non-destruc-
tive technique. A typical field
instrument has two parts - the
spectrofluorometer and the
controlling computer. Each of
these units is portable and
suitcase-sized. The ease of
use and lack of elaborate
preparation steps makes UV-
vis luminescence an excel-
lent choice for many hazard-
ous waste sites.
UV-vis luminescence com-
pares very favorably with
many field techniques
because it has high sensitiv-
ity, is non-destructive, and
can analyze thermally labile
samples or heavy com-
pounds like tars and polar
compounds like phenols.
This technology has a proven
track record with the U.S.
Coast Guard where it is used
for oil spill identification.
Extending this application
into various environmental
areas is the next step. The
Advantages
Limitations
Very sensitive for aromatic
and polyaromatic analytes
Inexpensive
Water is not an interfered
Non-aromatic analytes
usually do not interfere
Little or no pretreatment
required
Simple microextraction
procedure
Needs derivatives for most
non-aromatic analytes
Interpretation may require
special training
Fluorescence yields vary
EMSL-LV is committed to the
careful application of existing
technologies to novel uses in
environmental monitoring.
Current research should lead
to UV-vis fluorescence
instruments that are smaller,
cheaper, and more sensitive
to a wider range of analytes.
The development of reason-
ably priced small lasers may
eventually replace xenon
lamp sources. Rugged,
tunable lasers in the UV
range are being investigated.
Some monitoring can be
done with a filter fluorometer,
saving the cost of the scanning
step. The most versatile
applications remain in the area
of emission and synchronous
luminescence methods.
REFERENCE
Eastwood. D. and Vo-Dinh, T„ Molecular Optical Spectroscopic Techniques for Hazardous
Waste Site Screening, EPA 600/4-91/011, U.S. EPA, Environmental Monitoring Systems
Laboratory - Las Vegas, 1991
FOR FURTHER INFORMATION
For further information about UV-vis
luminescence methods, contact:
William H. Engelmann
Advanced Monitoring Division
U.S. EPA - Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas," NV 89193-3478
(702)798-2664
FTS 545-2664
For information about the Technology Support
Center at EMSL-LV, contact:
Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitonng Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
svEPA
Uritec ataies
Environmental Protection
Agency
Ervircr.r~ertai Mcn.torrg
Systens LaDoratory
P.O. Box 934.78
Las Vegas NV 89193-3478
.gust ' 992
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Robotics Technology
in Environmental
Sample Preparation
INTRODUCTION
The Environmental Monitor-
ing Systems Laboratory
(EMSL) in Las Vegas is
supporting the use of robotics
technology for routine
analyses of environmental
samples. The EMSL cur-
rently uses two robotics
systems for inorganic analy-
ses. Robotics minimizes the
incidence of operator error
and provides legally defen-
sible documentation following
chain-of-custody require-
ments. Increasingly sophisti-
cated robotics technology
coupled with software that is
user-friendly make robotics
attractive to laboratories that
are concerned about the
number of samples that can
be analyzed with consistently
high precision and improved
accuracy.
The EMSL-LV will provide
technical document review
and consultation to EPA
Regions who are considering
the purchase of a robotics
system. Evaluations of
manufacturers bids and
demonstrations of the
EMSL-LV systems are
available through the Tech-
nology Support Center at the
EMSL-LV. This technology
has increased the
Laboratory's ability to
perform quick-turnaround
analyses that are backed up
by strong documentation.
HARDWARE
In a sense, robotics hardware
is really analytical laboratory
hardware. When the robot is
used to weigh, dilute, and
prepare samples for chro-
matographic analysis, for
example, the hardware is a
table, a rack of sample jars,
an analytical balance, a
solvent vessel, a shaker, and
various arms and pipets that
allow the work to progress.
When a robotics network is
being designed, it is impor-
tant to consider parallel uses
that might be added for little
extra expense. This design
stage is critical in the cost
effectiveness of the system.
Scientists at the EMSL-LV
worked with manufacturers to
ensure that the instruments
were customized for particu-
lar uses, but were not con-
fined to a single application.
An operator still weighs out
the samples for analysis
because environmental
samples are too complex for
the robot to judiciously
segregate. For a soil sample
containing fines, coarse
gravel, and a few miscella-
neous twigs, human over-
sight is needed. The analyti-
cal balance, however, is tied
into the robotics network so
that transcription errors are
eliminated. Therefore,
robotics reduces human error
but does not eliminate human
intervention.
1204EX92
-------
SOFTWARE
Robotics systems come with
easily modified software
packages. Solvent amounts,
volume of internal standards
and surrogates, and time on
the shaker can be adjusted
easily. Software allows the
robot to recognize bar codes,
and to stop operation if a
sample is dropped or broken.
A strong round robin study
can be done when several
laboratories use the same
robotics software. The
elimination of operator bias
gives a better indication of
the true sources of variance
in any investigation. The
correct robotics system
provides chain-of-custody
records, fraud detection,
simpler analytical QA, and
round-the-clock performance.
The robotics system can be
described as a "computer
with arms". As such, it is no
smarter than the designers
and operators of the system.
The robot is not foolproof but
merely fool-resistant. It will
follow orders, add solvents,
and shake samples. It
cannot differentiate between
HPLC grade and less pure
methylene chloride, for
example. The responsibility
for good laboratory practice
remains with the analyst.
FUTURE RESEARCH
Robotics usage will be
enhanced with increased
ability for error recovery,
allowing the system to know
when samples have been
switched, for example, and to
correctly match samples with
their weights. Artificial
intelligence and expert
system technology might be
coupled with robotics to give
users systems that are
capable of more intricate
sample handling and decision
making. Microwave digestion
applications and complex
extraction procedures may
soon be programmable at the
robotics workstation.
REFERENCES
Hillman, D. C., P. Nowinski, M. A. Stapanian, J. E. Teberg, and L. C. Butler, "A Single Labora-
tory Evaluation of a Robotic Microwave Digestive System", EMSL-LV, 1992.
FOR FURTHER IN FORMA TION
For further information on robotics technology, contact:
Dr. Larry C. Butler
EMSL-LV
P.O. Box 93478
Las Vegas, NV 89193-3478
(702)798-2114
A copy of a video illustrating the EMSL-LV robot in action is available free to Agency users
from L. Butler.
^ t ^
^ I echnology "Z-
° O * 2
O >yjpport Q
4
roject
&
For information about the services available through the Technology Support Center at EMSL-
LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Geriach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
EPA
United States
Environmental Protection
Agency
Environmental Monitonng
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
Marcn "9S2
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Guidance for
Characterizing
Heterogeneous
Hazardous
Wastes
INTRODUCTION
The U.S. EPA and the U.S.
DOE are interested in ad-
dressing the special problems
presented in sampling hetero-
geneous hazardous waste
ranging from physically
diverse samples from landfills
to chemically mixed waste
found at many sites. This
area of sampling and analysis
poses problems to field and
laboratory personnel engaged
in the identification, classifica-
tion, and quantitation of
potentially hazardous
materials.
A recent workshop cospon-
sored by the EPA and DOE
Office of Technology Devel-
opment at the Environmental
Monitoring Systems Labora-
tory in Las Vegas (EMSL-LV)
resulted in a document that
provides guidance for scien-
tists working in this challeng-
ing area Characterizing
Heterogeneous Hazardous
Wastes: Methods and
Recommendations (EPA 600/
R-92/033) is available to
Agency personnel through
CERI. This document
contains valuable information
about proven protocols as
well as innovative technolo-
gies and recommendations
for further research. It
presents a typical case study
and a survey of the statistics
involved in design and
analysis.
PLANNING THE
STUDY
This chapter establishes a
rational diagram to follow in
the sampling and analysis
scheme. It is a five-step
process: preliminary plan-
ning, DQO process, sampling
and analysis design, sample
collection and analysis, and
data assessment. Sampling
heterogeneous matrices is
complex and presents a
challenge to those planning
the study.
Particular stress is placed on
asking the right questions at
the beginning of a study,
searching for any pertinent
historical data, and establish-
ing DQOs that are realistic.
Examples are provided that
prompt readers to look for
potential pitfalls in a sampling
scheme. Guidance is pro-
vided for the use of non-
traditional statistical sampling
plans and recommendations
are made for the establish-
ment of appropriate confi-
dence intervals.
QA/QC AND DATA
QUALITY
ASSESSMENT
In this chapter, the focus is
on quality assessment
strategies that can be used in
the sampling of heteroge-
neous matrices and in the
analysis of the subsequent
data. The importance of a
priori knowledge is stressed.
An effective quality assess-
ment process will provide
useable data without stipulat-
ing onerous procedures upon
the already overworked
sampling expert The correct
use of QA/QC samples such
as replicates, duplicates, and
co-located samples is
discussed. Field evaluation
samples and field matrix
spikes are recommended.
Even in unconventional
methods, the use of well-
planned QA/QC practices
can identify random or biased
error and trace the error to its
source.
The reader is referred to the
document A Rationale for the
Assessment of Errors in the
Sampling of Soils (EPA/600/
4-90/013) and to the software
package, ASSESS, available
through CERI to Agency
users.
1131EX92
-------
SAMPLE
ACQUISmON
This chapter specifies
sampling procedures that
should be followed when
sampling heterogeneous
hazardous waste - whether
contained or uncontained.
Contained waste is that found
in drums or boxes.
Uncontained waste is landfill
litter and debris piles that
exist at some sites. The
monitoring of regulated land-
fills is required by law.
Sometimes state monitoring
requirements are more
rigorous than federal guide-
lines.
Several questions arise when
sampling heterogeneous
waste. Is it possible to obtain
a sample of sufficient repre-
sentativeness that the
resultant data will truly reflect
the type and level of contami-
nation at the site? Is it
correct to physically separate
samples before analysis?
Should this separation be
based on physical character-
istics or on contamination
type? How can health risks
be fairly evaluated when the
contamination varies in level
from trace to high percent-
ages? Can homogenization
steps be taken without
compromising the quality of
the data?
These questions are ad-
dressed and guidance is
given in technologies ranging
from soil-gas measurement
and open-path FTIR to
geophysical methods and
aerial photography. Particu-
lar emphasis is placed on
sample collection procedures
and on handling steps. Field
screening methods are
discussed; X-ray fluores-
cence, vapor analyzers, and
various spectroscopic
techniques. Additional
discussion focuses on
radiography, gamma ray
assay, and neutron assay
methods.
ANALYTICAL
LABORATORY
REQUIREMENTS
This chapter deals with the
analysis of the samples as
they are received by the
analytical laboratory. If the
sample arrives as a
multiphase liquid or as a
collection of various solids,
decisions must be made
about the analysis. It is
crucial that any segregation
or homogenization of
samples be discussed with
the decision makers. The
DQOs should be consulted
again and, as always, QA/QC
plays a vital role in the
generation of useable data.
A flow chart is provided to
lead the reader through
several phases of the labora-
tory procedure. The consider-
ation of a priori knowledge is
important in the laboratory,
too.
Fusion methods are dis-
cussed for use in the analysis
of inorganic contaminants.
Neutron activation analysis is
suggested for some analyses
of radioactive samples.
Guidance is provided on the
choice of sample size and the
consideration of particle size.
A table compares various
radiation screening devices.
A section on the special
requirements of mixed waste
samples documents the need
for further refinement of
analytical methods and the
need for proper safety
precautions. Waste disposal
at the analytical laboratory is
discussed and the reader is
reminded that help exists in
this area from the American
Chemical Society's Task
Force on RCRA.
The importance of proper
reporting is stressed because
the need for understanding
reporting requirements in
advance is often critical in the
success of a study.
FOR FURTHER INFORMATION
For further information about the document, Characterizing Heterogeneous Hazardous Waste:
Methods and Recommendations (EPA/600/R-92/003) or to obtain a copy, contact:
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U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
Mr. (S.P.) John Mathur, EM-551
Office of Technology Development
Office of Environmental Restoration
and Waste Management
U.S. DOE
Washington, D.C. 20545
(301)353-7922
The Technology Support Center fact sheet series is developed and written by
Clare L Geriach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
&EPA
INTRODUCTION
Unnea States Environmental Monitoring February :9S2
Environmental Protection Systems Laboratory
Agency P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT TECHNOLOGY SUPPORT PROJECT
Correct Sampling
Using the Theories
of Pierre Gy
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas is interested in the
optimization of sampling
protocol, sampling tools,
subsampling techniques, and
sample analysis. The
importance of obtaining
representative samples in the
field and retaining their
integrity throughout the
analytical procedures is
fundamental to the genera-
tion of meaningful data.
Because sampling correct-
ness and representativeness
is critical to the collection and
handling of environmental
samples, the EMSL-LV has
hosted short courses pre-
sented by M. Francis Pitard
to explain and enforce the
theories of Pierre Gy relating
to sampling practice. The
inherent heterogeneity of
soils presents a particular
challenge to field personnel
who are responsible for
sampling hazardous waste
sites. This heterogeneity is
also a factor that must be
addressed by statisticians,
geostatisticians, and chemo-
metricians as they develop
sampling plans for the
location and frequency of
sampling. It affects the
manner in which analytical
chemists subsample in the
laboratory. Finally, heteroge-
neity influences the interpre-
tation of data and the deci-
sions made about the actions
taken to remediate contami-
nation at a site. The theories
of Pierre Gy present practical
sampling and subsampling
methods that can be applied
for little or no added expense.
Careful attention to these
techniques can result in
samples that better represent
the site and data that more
truly represent the sample.
True and complete homoge-
neity is impossible to achieve
because many factors,
including gravity, work
against it. But the extent of
heterogeneity and its effect
on environmental sampling
can be minimized. Estab-
lished methods from the
mining industry are appli-
cable to the sampling of soils.
The work of George
Matheron, father of
geostatistics, and Pierre Gy,
sampling expert, can provide
useful insights for environ-
mental scientists who are
faced with sampling a
complex matrix for trace
contaminants.
TYPES OF ERROR
Pierre Gy's theory addresses
seven types of sampling error
and offers proven techniques
for their minimization. The
seven major categories of
sampling error cover differ-
ences within samples. Other
differences can exist, such as,
within space (covered by
geostatistics) and within time
(covered by chronostatistics.)
The internal sample errors are:
Fundamental Error: This is
loss of precision inherent in
the sample and includes
particle size distribution. It is
circumstantial error. It can be
reduced by decreasing the
diameter of the largest par-
ticles or by increasing the
sample volume.
Grouping and Segregation
Error: Error due to non-
random distribution of
particles, usually by gravity.
It can be minimized by
compositing an analytical
sample from many randomly
selected increments or by
property homogenizing and
splitting the sample.
Long-range Heterogeneity
Error: This is fluctuating and
non-random. It is spatial and
may be identified by
variographic experiments and
can be reduced by taking
many increments to form the
sample.
Periodic Heterogeneity
Error: This fluctuation error
is temporal in character and
can be minimized by
compositing samples correctly.
Increment Delimitation
Error: Error tied to inappropri-
ate sampling design and the
wrong choice of equipment.
Increment Extraction Error:
This error occurs when the
sampling procedure fails to
precisely extract the intended
increment. Well-designed
sampling equipment and good
protocols are crucial.
Preparation Error: This error
is the expression of loss,
contamination, and alteration
of a sample or subsample.
Field and laboratory tech-
niques exist to address this
problem.
1041EX92OOC
-------
SAMPLE INTEGRITY
To truly represent a lot (or a
hazardous waste site) a
sample must be both accu-
rate and precise. Obviously,
100% accuracy and precision
cannot be obtained. It is
important to minimize the
error that is introduced in that
sample-taking and in the
subsequent handling,
subsampling, and prepara-
tion. If large-scale heteroge-
neity is ignored in a sampling
design, data generated from
the preferentially sampled
material will never truly reflect
the character of the site.
Some sampling devices and
protocols preselect fines or
coarses. This error is very
serious in environmental
work where concentration is
fundamental to decision
making. For example, if the
action level for compound X
is 100 micrograms/ kilogram,
a sample containing very fine
particles coated with com-
pound X would exceed action
levels but a large rock of the
same sample weight would
not. But both samples came
from the same site, in fact,
from the same cubic meter of
soil. If samples spanning all
particle sizes are sent to the
analytical laboratory, a very
confusing picture of the site
will emerge. When decisions
are made based on the
ensuing data, they will be
incorrectly made (or made
correctly by accident!)
DEVICES
Correct sampling devices are
essential to good sampling
protocol and to good labora-
tory practice. Pierre Gy
recommends scoops and
spatulas that are flat, not
spoon-shaped, to avoid the
preferential sampling of
coarse particles. Additional
care must be taken at the
analytical laboratory, where
error can be introduced by
poorly designed riffle split-
ters, spatulas, and vibrating
tools, ft is recommended that
the sample be subsampled
using a system of alternate
shovelling wherein a large
sample is "dealt out" into
several smaller piles. One of
these subsamples is chosen
for the analysis. This method
avoids preferential sampling
by saving the subsample
selection until last.
SUMMARY
Methods developed for the
mining industry can provide
environmental scientists with
guidance for the correct
sampling and subsampling of
soils. The sampling theories
of Pierre Gy are applicable to
most sampling events at
hazardous waste sites and to
the successful subsampling
of those samples at the
analytical laboratory. Greater
sample volume yields data
that better represent the site.
Careful use of practices
suggested by Pierre Gy will
result in higher quality data
for little or no added expense.
REFERENCES
Pitard, F. F., Pierre Gy's Sampling Theory and Sampling Practice, 2 Volumes, 1989, CRC
Press, Inc., Boca Raton, Florida.
FOR FURTHER INFORMATION
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For more information about the application of
Pierre Gy's theories to environmental sampling,
contact:
Dr. George Flatman
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2628
For information about the Technology Suppo
Center at the EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
EMSL-LV
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
f/EPA
Utv.ec States
Envrcnmentai Protector.
Agency
Systems Laocrato'y
P O Box 93473
Las Vegas NV 39193-3473
Sec;a~ce' ' 552
INTRODUCTION
The Environmental Monitor-
ing Systems Laboratory in
Las Vegas (EMSL-LV) has
an excellent background in
the preparation and analysis
of non-typical samples that
require special care, in-depth
knowledge, and high-tech
instrumentation. The EPA
Regions are welcome to
submit special samples to the
EMSL-LV through the
Technology Support Center.
Representative sampling and
subsampling present chal-
lenges to field and laboratory
personnel. The EMSL-LV
has experience and expertise
in the handling of complex
and heterogeneous matrices
and in the interpretation of
results from non-routine
samples.
The following examples
illustrate the wide range of
capabilities and analytical
services available through
the EMSL-LV.
DOUBLE EAGLE, 4TH
ST. NPL SITES
At the request of Region 6,
the EMSL-LV analyzed
complex mixtures of tar,
asphalt, oily soil, sludge, and
water samples from the
Double Eagle and 4th St.
NPL Waste Oil Sites One
main goal was to use various
organic and inorganic mark-
ers to allow source identifica-
tion between the two sites.
Despite severe sample
heterogeneity problems and
matrix inconsistencies within
each site, numerous organic
and inorganic markers were
identified using ICP-MS and
GC/high resolution MS. This
allowed unambiguous source
identification of samples from
either of the two sites. It was
then possible to correlate off-
site wastes to one of the two
sites.
A decision to use complete
sample dissolution in closed
high-pressure digestion
vessels for the inorganic
indicator parameters paid off
because volatile osmium was
detected. This rarely de-
tected analyte would not
have been noticed if conven-
tional methods of sample
preparation had been used.
The expertise gained in
sampling, extraction, diges-
tion, and analyses of these
complex samples adds to the
existing experience at the
EMSL-LV.
JACK'S CREEK NPL
SITE
The EMSL-LV received
unusual soil samples from
Region 3's Jack's Creek NPL
Site. The samples contained
"an unknown purple com-
pound". This compound was
highly soluble in ethanol and
other organic solvents but not
in water. Ethanol extracts
were analyzed by ICP-MS
with a focus on compounds
that could impart a purple
color (such as chromium,
nickel, and iodine). Iodine
was detected in significant
quantities and was verified in
several qualitative wet
chemistry tests as complexed
iodine. GC/MS analysis of a
methylene chloride extract of
the compound produced two
identifiable peaks. The most
likely match was leuco crystal
violet, a reduced form of the
aniline dye known as crystal
violet. The presence ot
complexed iodine further
confirmed this identification
as developed leuco crystal
violet. Through this series of
analytical deductions,
multidisciplinary scientists at
the EMSL-LV were able to
identify the mystery com-
pound from the Jack's Creek
Site.
The Jack's Creek Site also
required analyses for chlori-
nated dibenzofurans. These
compounds were success-
fully quantified in the pres-
ence of chlorinated
diphenylether interferences
by careful deconvolution of
the GC/high resolution MS
results. Quantification of
these furans has not tradi-
tionally been attempted under
such conditions.
1310EX92ODC
-------
INDIANA HARBOR
RCRA SITE
Indiana Harbor is a RCRA
facility in Region 5 The
Region needs to classify the
sediments in the harbor to
decide on the eventual
disposal of dredged material.
Oily sediment samples had
been analyzed previously by
a CLP laboratory but the
-esults were inconsistent
between the total analyses
and the toxicity characteristic
leaching procedure (TCLP).
By using extra care in
sampling and homogeniza-
tion techniques, as well as
use of excellent laboratory
practices (ELP), EMSl-LV
scientists were able to
provide the Region with
consistent results.
NORTH DRIVE NPL
SITE
The North Drive NPL Site in
Region 5 features an area
contaminated with Prussian
blue (ferrous and ferric
cyanide compounds). Again,
routine CLP analyses had
yielded unsatisfactory results.
The Prussian blue com-
pounds at the site were found
to be mixed with sulfides
which distill along with
significant quantities of
cyanide. The traditional CLP
cyanide methods are inaccu-
rate in the presence of sulfide
interference.
EMSL-LV scientists re-
searched alternate cyanide
methods that are less
affected by sulfide interfer-
ences. The ASTM method
for weak-acid dissociable
(WAD) cyanide gave results
that were consistent when
synthetic iron cyanide
solutions containing sulfide
interferences were analyzed
The North Drive Site samples
are now being analyzed with
the method which is easier to
use and holds promise for all
high-suIfide samples requir-
ing cyanide analysis.
INNOVATIVE
METHODS
The EMSL-LV is proud to
maintain the instrumentation
and personnel necessary to
perform innovative analysis
of difficult and unusual
samples. Teaming state-of-
the-art equipment with highly
specialized, multidisciplinary
technical staff enables, the
Laboratory to provide high
quality service to the EPA
Regions. The staff at EMSL-
LV is keeping current with the
analytical demands of an
increasingly complex environ
ment.
REFERENCES
Report on the Identification and Analysis of Potential Indicator Parameters for Sourcing Off-
Site Contamination (Double Eagle and 4th Street Refinery NPL Sites), EMSL-LV TSC-17, July
1992.
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FOR FURTHER INFORMATION
For information about accessing the special analytical services available through the EMSL-L V
Technology Support Center contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
Dr. Don Betowski
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2116
For further Information on Special Analytical Services contact:
Dr. Wayne G. Sovocool
(702) 798-2212
Gary L. Robertson
(702) 798-2215
Dr. Edward M. Heithmar
(702) 798-2626
Tammy L. Jones
(702) 798-2144
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
United States Environmental Monitoring
Environmental Protection Systems Laboratory
Agency P O. Box 93478
Las Vegas NV 89193-3478
OFFICE OF RESEARCH AND DEVELOPMENT ~
Performance *v
Evaluation " .
Samples ^
v»EPA
INTRODUCTION
THE PES INVENTORY
Quality assurance (OA) and
quality control (QC) are
integral features of the
Agency's programs for the
detection and measurement
of contaminants in the
environment. OA monitors
the planning, implementation
and completion of sample
collection and data analysis
activities. The Environmental
Monitoring Systems Labora-
tory - Las Vegas (EMSL-LV)
has considerable experience
in the design of effective OA
programs. The Analytical
Operations Branch (AOB) of
the Office of Emergency and
Remedial Response has
been preparing Performance
Evaluation Samples (PES)
with advice from the EMSL-
LV. AOB uses a Quality
Assurance Technical Support
Complex PESs for a variety
of Superfund needs are
provided by the AOB through
QATS with oversight and
technical direction from the
EMSL-LV. These samples
are usually single blind
because the physical appear-
ance probably alerts the
analyst to the fact that they
are PESs but the identity and
concentration of the analytes
are not known.
(QATS) contractor also
located in Las Vegas to
prepare the PES. The
incorporation of PESs of
known concentrations into a
study is useful for evaluating
the accuracy of the analytical
procedures for real samples.
The AOB is responsible for
the production and distribu-
tion of PESs; the Office of
Research and Development
(ORD) provides technical
direction and independent
oversight.
Through the QATS program,
the EMSL-LV is assisting in
the development, testing and
distribution of PESs. PESs
are available from QATS for
a wide range of contaminants
in various matrices. The
most frequently requested
The inventory of PESs
available from the QATS
includes low/medium organic
compounds in water and in
soil, low/medium inorganic
compounds in water and in
soil, chlorinated dioxins or
dioxins/furans in soil and in
sediments, low concentration
organic and inorganic
compounds in water, high
concentration inorganic
compounds in soil, soil/oil, oil,
Septemoer 1991
TECHNOLOGY SUPPORT PROJECT
PESs are water and soil
matrices with contaminants
that are encountered in the
contract laboratory program
(CLP). The CLP is also
managed by AOB.
PESs can be zero blind,
single blind, or double blind.
When the analyst knows that
a sample is a PES and also
knows the identity and
concentration of the analytes
of interest, the sample is zero
blind. Zero-blind PESs are
often called laboratory control
samples (LCS). When the
sample is known to be a PES
but the identity and concen-
tration of the analytes are not
known, the sample is single
blind. When the analyst is
not aware that the sample is
a PES, it is double blind.
and oil/water, and individual
aroclors in soil.
The inventory is growing as
new methods are developed
for the preparation and
preservation of PESs.
Requests for site-typical
PESs are filled if the require-
ment is general and is typical
of several site categories.
The development of site-
specific PESs for a single site
is too expensive.
093SMEX91
-------
PES BY SITE
CATEGORY
The National Priority List
(NPL) recognizes more than
20 industrial site categories,
ranging from battery acid
sites to gasoline stations.
The similarity of contami-
nants within these site
categories is sufficient to
warrant PES batches that
address the needs of most
individual sites within a
category. The dissimilarity
between samples within a
category is usually a function
of characteristics of the
sample matrix.
The AOB, QATS and the
EMSL-LV work with the
Regional site managers to
provide PESs for various site
categories in a variety of
matrices. If a PES is not
available for a particular neea
AOB, QATS, and the ORD will
investigate the feasibility of
designing a customized PES
Advantages
Limitations
Provides information
about accuracy
Legally defensible
data
Interlaboratory
comparisons
Difficulty matching
matrices
Visibility of PES
Application to other
situations must be
explored
FUTURE PLANS
The QATS is expanding its
PES inventory. The Target
Analyte Profiles (TAP)
currently being developed by
QATS describe sites by
category. This system is
based on the CLP Analytical
Results Database (CARD)
which contains a compilation
of analyte/concentration
information from Superfund
sites in the Regions.
Meeting the existing needs
for PESs and for technical
support in their use and
evaluation is a major goal, as
is responding to growing
Regional demands for quality
PESs within the hazardous
waste programs.
Another effort is the estab-
lishment of Regional reposi-
tories for PES. This inven-
tory will enable the Regions
to evaluate the performance
of contract laboratories by
comparing results obtained
for the same PES.
Working within AOB and
ORD guidelines, QATS is
ready to meet the needs of
the Regions.
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FOR FURTHER INFORMATION
For further information on the PES available and how to order them, contact:
Larry Butler, Deputy Project Officer
U.S. EPA
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2114
FTS 545-2114
Jim Barron, Project Officer
U.S. EPA, Analytical Operations Branch
Office of Emergency and Remedial Response
401 M Street S.W.
Washington, D.C. 20460
(202) 260-7909
FTS 260-7909
For information about the Technology Support Center at EMSL-LV, contact:
Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
&EPA
INTRODUCTION
Unitec States
Environmental Protection
Agency
Envircnmental Mcnitonng
Systems Laboratory
P O Box 93478
Las Vegas NV 89193-3478
Ncvemoer 1991
TECHNOLOGY SUPPORT PROJECT
Monitoring
Airborne
Microorganisms
The Environmental Monitor-
ing Systems Laboratory - Las
Vegas (EMSL-LV) is evaluat-
ing methods for monitoring
airborne microorganisms.
Monitoring indoor air spans
several research areas
including radiochemistry
(radon, low-level radiation),
analytical chemistry (formal-
dehyde, cleaning solvents),
and microbiology (fungi,
bacteria, and other microor-
ganisms). Through a coop-
erative research and devel-
opment agreement (CRDA)
with Dow-Corning, microbi-
ologists at the EMSL-LV are
investigating the use of
various monitoring tech-
niques that assess the type
and extent of microbiological
contamination in indoor air.
It was necessary to create a
laboratory setting which
closely resembled a typical
room but which could be
controlled and monitored by
scientists who wished to
investigate various types of
contamination, air movement
patterns, and the efficacy of
methods for their removal.
This exposure chamber
(known locally as "the
plywood palace") is located in
a research laboratory at the
EMSL-LV. The room is about
13'X13'X8' and is constructed
of plywood sheets with a 6-
inch insulation between the
outer and inner walls.
Since its construction in
1990, the room has served
as a test facility for various
research efforts. Principal
among these, so far, are
evaluations of methods for
monitoring the quality of
indoor air into which fungal
spores have been introduced.
Future efforts will include the
evaluation of various mitiga-
tion agents and indoor air
purification systems, the
effects of human and me-
chanical movement on the
dispersal of microorganisms
in an enclosed area, and
comparisons of testing and
monitoring procedures for the
accurate evaluation of indoor
air quality.
THE FACILITY AND
EQUIPMENT
The indoor air facility is a
custom-built room that has a
well-sealed viewing window
and an enclosed anteroom
that serves as a suiting-up
area for scientists donning
respirators and protective
clothing. The room has five
sampling trees made of
stainless steel and equipped
with thermocouples and
humidity sensors. Thus far,
all testing has been done in
an atmosphere at constant
temperature and humidity.
The airflow is 150 cfm, which
is the standard recom-
mended circulation for indoor
air. The room is equipped
with a HEPA (high efficiency
particle air) filter that removes
airborne particles greater
than 1 um in diameter. The
room has a wood floor, that is
presently covered with carpet
to check the behavior of
airborne microorganisms in
the presence of absorbing
materials. The simplicity of
the room makes it a perfect
mini-lab, able to adapt to
various research require-
ments.
The equipment used to
measure the extent and
pathways of indoor air
contamination varies from
simple gravimetric methods
to expensive mechanical
samplers. The simplest
method for retrieving fungal
spores is the placement in
the room of Petri dishes
containing an agar medium.
The drawback of this method
is that it relies on gravity and
therefore preferentially
samples larger species.
Samplers that use a vacuum
to draw indoor air onto an
agar coated plate may err on
the side of lighter species. A
laser technique is being
evaluated, too. So far, the
most promising instrument for
the detection of fungal spores
is a six-stage sampler that is
a tiered bank of sieve-like
agar plates that filter out the
larger species at the top and
reduce gradually to the
smallest species at the
bottom. Several tests have
been run that indicate this
method is the most precise of
the methods tested for
monitoring studies of fungal
spores.
11S8EX31
-------
ADVANTAGES AND
LIMITATIONS
The obvious advantage to
cor -jcting monitoring
eva.nations in a simulated but
typical room is that results
can be assumed to reflect the
performance of testing
equipment in a non-controlled
environment. The room itself
is easily changed to measure
the effect of various param-
eters, such as fluctuating
temperature and humidity,
the presence of carpeting,
the use of biocides, and
changes in the construction
materials of the room.
A limitation of this facility is its
inability to represent certain
indoor environments, such as
an open foyer, an older
edifice constructed of materi-
als that are no longer avail-
able, or an isolated situation
that may set the biological
stage for a new or unnoticed
microorganism.
The facility is a good working
model that is flexible enough
to provide an excellent
testing ground for various
monitoring devices and
methods that target specific
microorganisms in typical
indoor air.
FUTURE
Questions continue to arise
about the quality of indoor air,
the nature of microorganisms
in an indoor environment,
and the effective use of
various biocides. The EMSL-
LV will continue to test
monitoring techniques
designed to address these
concerns. Future work in this
facility will expand the
species list to include bacte-
ria as well as fungi. The
ability to characterize and
enumerate indoor air con-
tamination is the first step in
solving an environmental
problem of widespread
concern.
REFERENCES
Biological Contaminants in Indoor Environments, P. R. Morey, J. C. Feeley, Sr., J. A. Otten,
eds., STP 1071, ASTM, Philadelphia, PA, 1990
FOR FURTHER INFORMATION
For further information about the monitoring of airborne microorganisms, contact:
Mr. Stephen Hern
Exposure Monitoring Program
U.S. Environmental Protection Agency
Environmental Monitoring Systems
Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2594
FTS 545-2594
FAX (702) 798-2454
10GV
For information about the Technology Support Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
FTS 545-2270
FAX (702) 798-2637
The Technology Support Center fact sheet series is developed and written by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas.
-------
INTRODUCTION
BACKGROUND
POTENTIAL USES
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P O Box 93478
Las Vegas NV 89193-3478
April 1993
TECHNOLOGY SUPPORT PROJECT
Biosensors
For
Environmental
Monitoring
EMSL-LV is conducting
research on biosensors for
environmental monitoring
applications. This research is
designed to address a critical
and growing need for
real-time and in situ monitor-
ing devices which can be
used at Superfund sites and
RCRA facilities as well as for
ground water monitoring.
Because biosensor technol-
ogy lends itself to fast,
economical and continuous
monitoring capabilities,
development of these
systems to complement
classical analytical measure-
ments is expected to result in
a substantial cost benefit,
especially when sample
turnaround time and cost per
analysis are important
issues. Biosensors are
currently being considered
for development for detec-
tion of environmental pollut-
ants such as polychlorinated
biphenyls (PCBs), chlori-
nated hydrocarbons, ben-
zene/toluene/xylene (BTX)
and pesticides.
A biosensor is an analytical
device composed of a
biological sensing element
(enzyme, receptor or anti-'
body) in intimate contact with
a physical transducer (optical,
mass or electrochemical)
which together relate the
concentration of an analyte to
a measurable electrical
signal. In theory, and verified
to a certain extent in the
literature, any biological
sensing element may be
paired with any physical
transducer. The majority of
reported biosensor research
has been directed toward
development of devices for
clinical markets; however,
driven by a need for better
methods for environmental
surveillance, research into
this technology is also
expanding to encompass
environmental applications.
The unique characteristics of
biosensors will allow these
devices to complement
current field screening and
monitoring methods such as
immunoassay test kits as
well as fiber-optic and
chemical sensors. For
example, enzyme-based
biosensors show the poten-
tial for continuous monitoring
of compounds such as
phenolics in process
streams, effluents and
groundwater. Further, since
certain of these devices can
operate in high concentra-
tions of organics such as
methanol and acetonitrile,
these biosensors show
promise for in situ monitoring
of mixed organic wastes.
Other potential applications
include down-hole or perim-
eter groundwater surveil-
lance as well as process
stream monitoring for
remediation procedures.
Antibody-based biosensors
show the potential for
coupling immunochemical
specificity with recent ad-
vances in fiber-optics and
microelectronics. These
biosensors may yield instan-
taneous analysis of a wide
variety of analytes without
the need for multiple re-
agents and incubation steps
required for immunoassay
kits.
FUTURE A variety of laboratory environmental pollutants. some general requirements
DEVELOPMENT prototype biosensors have Although specific require- for biosensors used in
been reported which measure ments must be met for each environmental applications
a fairly broad spectrum of field monitoring scenario, are listed in the following
table.
1072ODC93
-------
FUTURE
DEVELOPMENT
(Continued)
Requirement
Specification Range
Cost
Portability
Assay time
Personnel training
Format
Matrix
Sensitivity
Dynamic range
Specificity
$1-15 per analysis.
Can be carried by one person; no external power
1 -60 minutes
Can be operated after 1-2 hour training period
Reversible, continuous, in situ
Minimal preparation for groundwater, soil extract,
blood and urine
Parts per million to parts per billion
At least two orders of magnitude
Enzymes/receptors:
specific to one or more groups of related compounds
Antibodies:
specific to one compound or closely related group of
compounds
FUTURE
RESEARCH
In addition to the basic and
applied research conducted
through EMSL-LV, efforts
are currently underway for
laboratory evaluation and
field testing of commercial
biosensors in preliminary
stages of development as
well as those which are "in
the queue" for introduction
into the commercial market.
REFERENCE
Biosensors for Environmental Monitoring, K. R. Rogers & J. N. Lin (1992) Biosensors &
Bioelectronics 7, 317-321.
FOR FURTHER INFORM A TION
For further information about biosensors for environmental monitoring, contact:
Dr. Kim R. Rogers
Exposure Assessment Research Division
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2299
For information about the Technology Support Center at EMSL-LV, contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed by Clare L. Gerlach, Lockheed
Environmental Systems & Technologies Company, Las Vegas.
-------
United States
Environmental Protection
Agency
&EPA
The Need:
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
June 1993
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Field-Portable Scanning
Spectrofluorometer
Field-portable instru-
ments are available for
the qualitative and
quantitative evaluation
of volatile organic
compounds and non-
volatile inorganic
elements. Compounds
that fall between these
volatility extremes have
received less attention
in recent years. And
yet these compounds
comprise a surprising
number of important
contamination catego-
ries at Superfund and
RCRA sites.
Polyaromatic hydrocar-
bons (PAHs) in com-
plex mixtures such as
oils, creosotes, and tars
are found on numerous
hazardous waste sites
and, because of their
high molecular weight,
present special chal-
lenges to analytical
chemists and instru-
ment developers.
These compounds have
relatively high lumines-
cence yields and,
therefore, can be readily
measured by spectroflu-
orometry.
A recent technology
that is in the production
prototype stage is the
Field-Portable Scanning
Spectrofluorometer
(FPSS). It is a light-
weight battery-operated
instrument that has
shown early promise as
a screening device for
petroleum oils, PAHs
and, especially, creo-
sotes.
Creosote (wood preser-
vation) and coal gasifi-
cation sites are wide-
spread, especially in the
southeastern United
States. These are
complex sites that
usually have various
PAHs in addition to the
creosotes. These
compounds are cur-
rently quantified by gas
chromatography but
their tarlike composition
makes them difficult to
detect and destructive
to columns and detec-
tors. The development
of a field-portable
instrument to rapidly
identify and quantify
PAH mixtures, such as
creosotes, oils, as-
phalts, or coal tars is
an important step in
filling a field analytical
niche.
The FPSS prototype is
ready for field demon-
stration and compara-
tive studies. It is
anticipated that the
FPSS will provide a
more rugged and less
expensive alternative to
traditional methods for
screening PAHs.
2016EX930DC
-------
The Use:
Scientists working at
the Environmental
Monitoring Systems
Laboratory-Las Vegas
have performed labora-
tory evaluations of the
battery-operated FPSS
developed by T. Vo-
Dinh and his co-work-
ers at Oak Ridge
National Laboratory.123
Table 1 shows the
physical characteristics
of the instrument.
The FPSS can perform
emission and synchro-
nous wavelength
scans. In the emission
mode, relatively low
detection limits are
achieved (Table 2).
The emission mode is
useful for the determi-
nation of total PAHs or
in identifying and classi-
fying oils. In the syn-
chronous mode both
the excitation and
emission monochroma-
tors are scanned simul-
taneously with a con-
stant wavelength offset.
The advantage to syn-
chronous mode is that it
separates spectra of
compounds with a
different number of
fused rings, sharpens
spectra, and allows the
relative amount of
various PAH classes to
be quantified.
The FPSS consists of
three parts: a small
Table 1. Physical Characteristics of the Field-
Portable Scanning Spectrofluorometer
SIZE
WEIGHT
Instrument
Battery Pack
48 x 40 x 21 cm
(18.5x11.5x8")
31 x 18x15 cm
(12x7x6")
11.5 kg
11.0 kg
suitcase-sized instru-
ment that houses the
optics and electronics,
a battery pack, and a
lap top computer used
for instrument control,
data storage and
analysis. The spectral
coverage of the instru-
ment is 210-650 nm.
The instrument param-
eters are chosen by the
operator who uses the
computer to control the
instrument.
The FPSS can be oper-
ated two ways: using a
standard fluorescence
cuvette cell or a bifur-
cated optical fiber. The
optical fiber attachment
is 2-meter long and
allows direct screening
of water samples. The
cuvette can be used
with liquid samples or
extracts of soils. When
the optical fiber attach-
ment is used, care must
be taken to avoid inter-
ference from light. This
can be done by cover-
ing the sampling area
with a black cloth.
Table 2. Limit of Detection (S/N = 3)
SYNCHRONOUS
EMISSION
SYNCHRONOUS
(cuvette)
(cuvette)
(fiber)
Perkin Elmer LS50 0.17'
(laboratory instrument)
0.02
24
FPSS prototype 3.5
0.55
1
' All concentrations ng/mL of anthracene
The Limits:
Some areas of concern
exist relative to the
successful operation of
the FPSS in a field
situation. The rugged-
ness of the optical
components is crucial
to the in situ applicabil-
ity of the system. The
unit was shipped from
Oak Ridge National
Laboratory to the
EMSL-LV without
affecting the optical
alignment or electron-
ics. The instrument has
been demonstrated to
withstand normal
handling in the labora-
tory. The instrument is
(continued on next page)
-------
The Limits:
(continued)
The Status:
ready to be demon-
strated at a hazardous
waste site.
The FPSS is particu-
larly suited to the
classification or identifi-
cation of oils or PAH
compounds. It can also
be used with site-
specific standards to
quantify total oils or
PAHs. It can be used to
determine relative
amounts of the PAH
classes present. In
rare instances, like
spills of solvents or
PAHs with very high
fluorescent yields and
sharp structures such
as benzo-(a)pyrene, it
can be used to detect
and quantify identified
PAHs. There is greater
spectral separation
capability when the
instrument is operated
in synchronous mode
but lower detection
limits can be achieved
using the emission
mode.
Laboratory evaluations
and research efforts
have resulted in a draft
fluorescence method
for the analysis of
PAHs which is in the
final stages of accep-
tance by the American
Society for Testing and
Materials. A compari-
son of the optical fiber
mode and the standard
cuvette mode was per-
formed on samples of
anthracene in metha-
nol. This study showed
the cuvette mode to be
2-3 times more sensi-
tive than the optical
fiber mode.
Synchronous lumines-
cence has been dem-
onstrated to be useful
in characterizing crude
and fuel oils.4 The
technique can be used
to produce spectral
fingerprints for the
identification of oil
contamination types
and sources. The
FPSS proved its ability
in a study comparing
samples from an oil
spill with samples of the
source oil which were
provided by the U.S.
Coast Guard.
The FPSS has shown
considerable promise
for the classification
and quantitation of PAH
compounds and oily
mixtures. The next
step is to take the
portable instrument to a
hazardous waste site
where it can be evalu-
ated against standard
methods in a well-
planned experimental
design. The develop-
ment of the FPSS was
sponsored by the
EMSL-LV and commer-
cialization is being
planned.
References: 1 T. Vo-Dinh, "Synchronous Excitation Spectroscopy" in Modern Fluores-
cence Spectroscopy, Vol. 4, Edited E.L. Wehry, Plenum Press, New York,
1981, pp. 167-192.
2 T. Vo-Dinh, "Synchronous Luminescence Spectroscopy: Methodology and
Applicability", Applied Spectroscopy, Vol. 36, 576, 1982.
3 J.P. Alarie, Vo-Dinh, T., Miller, G., M.N. Ericson, S.R. Maddox, W. Watts,
D. Eastwood, R.L. Lidberg, and M. Dominguez, "Development of a Battery-
Operated Portable Synchronous Luminescence Spectrofluorometer", in
press, (Review of Scientific Instruments).
4 K.J. Siddiqui, Lidberg, R.L., Eastwood, D., and Gibson, G., "Expert Sys-
tems for Classification and Identification of Waterborne Petroleum Oils",
Monitoring Water in the 1990s, Meeting New Challenges, ASTM STP 1102,
J.R. Hall and G.D. Glysson, Editors, American Society for Testing and
Materials, Philadelphia, 1991.
-------
The Contacts For further information about synchronous luminescence spectroscopy,
contact:
Mr. William H. Engelmann, Manager
Advanced in Situ Monitoring Program
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2664
For information about evaluating the FPSS at a hazardous waste site
(Superfund or RCRA), contact:
Mr. Ken Brown, Manager
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
The Technology Support Center fact sheet series is developed by Clare L Gerlach,
Lockheed Environmental Systems & Technologies Company, Las Vegas
^ I echnology "£¦
o (K z
o ^upport Q
'-A Project £
-------
United States
Environmental Protection
Agency
&EPA
The Need
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
January 1994
OFFICE OF RESEARCH AND DEVELOPMENT
TECHNOLOGY SUPPORT PROJECT
Immunochemical Analysis
Of Environmental
Samples
An EMSL-LV
Innovative
Technology
Field methods used for
detecting compounds of
environmental signifi-
cance traditionally have
been derived from
standard laboratory
methods. When labo-
ratory methods are
adapted to the field,
they are often relatively
slow, insensitive,
expensive, and require
bulky transportable
equipment and skilled
operators. There is a
need for rapid, sensi-
tive, low-cost, portable,
and simple field meth-
ods for analysis of
environmental samples.
Immunochemistry
offers those advan-
tages. The only spe-
cialized equipment
needed is a spectro-
photometer, microtiter
plates or test tubes,
precision pipets, and
immunologic reagents.
Commercial manufac-
turers sell kits for field
screening, and new
equipment and meth-
ods are being devel-
oped for rapid, accurate
field analysis of a wide
variety of analytes,
such as heavy metals,
dioxins, and PCBs, that
are found at Superfund
and RCRA sites. As a
result the regulator and
regulated communities
view immunochemistry
as a powerful technol-
ogy for screening
analysis of environmen-
tal contaminants.
Immunochemistry
includes techniques
such as immunoaffinity
chromatography and
immunoassay. Sample
preparations based on
immunoaffinity take
advantage of the
attraction between an
antibody and a specific
analyte. The procedure
has great potential for
cleanup of complex
samples like soils and
sludges. By rinsing a
sample over an anti-
body-treated surface,
chemists can isolate
particular compounds
that adhere to the
antibody. The isolated
compound is then
eluted from the immobi-
lized antibody and is
ready for analysis by
chromatography or
immunoassay. One
common immunoassay
is the enzyme-linked
immunosorbent assay
(ELISA). In this tech-
nique, the selectivity of
the antibody for the
analyte and the result-
ant antibody-analyte
complex is the basis for
the specificity of immu-
noassays.
1
9311-0146EX93ODC
-------
The Use
The Environmental
Monitoring Systems
Laboratory - Las Vegas
(EMSL-LV) is pioneer-
ing an investigation into
the usefulness of
immunochemical
techniques for monitor-
ing the extent of con-
tamination in environ-
mental and biological
matrices. EMSL-LV
has developed and
demonstrated several
of these techniques and
believes that they hold
great promise for the
quantitative analysis of
target analytes for use
in ground-water surveil-
lance, in situ hazardous
waste site monitoring,
and assessment of
human exposure.
Current work involves
the analysis of chemi-
cals like PCBs,
nitroaromatics, and
certain pesticides that
are difficult to analyze
by other analytical
methods. EMSL-LV
has sponsored two
national meetings that
focused on regulatory
issues and technologi-
cal advances in envi-
ronmental immuno-
chemistry. These
meetings brought
together government,
industry, and university
scientists to discuss
problems of mutual
interest in the field.
A 1993 Technology
Support Center project
at a Superfund site in
Region 5 demonstrated
the usefulness of
immunochemical
methods for screening
PCBs in; soil and river
sediment. This project
was an example of
cooperation between
EPA, DOE, the state of
Michigan, and various
contractors. Two
immunoassays and a
chloride-ion specific
electrode were used on
site and the real-time
analytical results were
compared with stan-
dard GC results from
EPA method 8081.
Preliminary results
show good agreement
between the immuno-
assays and GC and
even stronger correla-
tion could be achieved
with tighter quality
control measures.
In addition, other EPA
offices have applied
immunochemistry for
screening and analysis
in their programs. The
Office of Water has
used immunoassays to
screen indirect discharges
of specific analytes for
permitting under the
Clean Water Act
(304h). Sample analy-
sis data may soon be
used for comparison
and compliance moni-
toring within selected
industries, such as
commercial laundries.
The Office of Pesticides
is looking at ways to
shorten the pesticide
registration process by
using immunochemistry
as a cost-effective
technology.
Other government
agencies and universi-
ties are studying immu-
nochemical methods.
The Food and Drug
Administration (FDA)
may use immunoas-
says to obtain data for
the calculation of safe
concentrations of
residues. A recent
university project used
immunoassays to track
contamination during
the 1993 Midwestern
flood. In applications
as diverse as organic
geochemistry and
military operations,
immunochemical
methods have been
used for volatile organic
compound measure-
ment. The U.S. Depart-
ment of Agriculture
(USDA) is integrating
immunoassays into
rapid test procedures
for detection of resi-
dues in meat and
poultry. Results from
these tests will be used
in regulatory and
compliance programs
for veterinary drugs,
sanitation, and pest
control. The National
Institute for Occupa-
tional Safety and Health
(NIOSH) has applied
immunoassays to
herbicide research,
clinical analysis,
biomarkers, and im-
mune biomonitoring.
They use the methods
to detect morphine
factor, alachlor, atr-
azine, cyanazine,
metalachlor, and 2,4-D.
State laboratories have
analyzed soil samples
and water from private
wells using immuno-
chemical test systems
for triazine (atrazine)
samples.
The results of EPA's
Superfund Innovative
Technology Evaluation
2
-------
The Use
(continued)
(SITE) studies indicate
a strong correlation
between field immuno-
assays, laboratory
immunoassays, and
gas chromatography-
mass spectrometry.
Another field use of
immunochemistry that
is being explored at
EMSL-LV, the personal
exposure monitor
(PEM), may revolution-
ize safety and exposure
requirements for work-
ers who deal with
hazardous chemicals.
Immunochemical
dosimeter badges can
be used to detect
pentachlorophenol and
nitroaromatics, and are
being developed for
parathion and
chloropyrifos. These
badges are lightweight,
inexpensive, quick, and
provide a real time
indication of exposure.
The Limits
The use of immuno-
chemical techniques is
gaining acceptance in
the environmental
sciences. One need
that is being addressed
is that of specificity.
Frequently, immunoas-
says are available for a
class of compounds,
like PCBs. Specific
quantitation for each
component has been
difficult.
The development of
PEMs, for example,
must address the
question of diffusion of
chemicals through a
semipermeable mem-
brane, the optimum
concentration of the
antibody, detection
limits of the PEM and
quantitation by immu-
noassay, the efficiency
of the antibody in
capturing the analyte,
and the capacity of the
device.
Validation studies of
reproducibility, matrix
effects, field trials, false
negatives/positives,
and correlation with
other tests will assist
acceptance of immuno-
chemical methods at
Superfund and RCRA
sites. The legal defensi-
bility of immunochemi-
cal results is yet to be
determined.
Advantages and limita-
tions are summarized
below.
Advantages
Limitations
• Field portable
• User friendly
• Quick and inexpensive
• Potential for wide range of
analytes
• Useful for many matrices
• Low detection limits
• Separate immunoassay needed
for each analyte
• More complex analysis required
for quantitation of specific
analytes
• Long development time for new
antibodies and methods
The Status
One new avenue of
investigation is the use
of antibody-coated,
fiber-optic immuno-
sensors. Another
application is the
integration of robotics
capability for high
sample throughput and
the development of a
tiered analytical ap-
proach, i.e., biological
and environmental
samples, biomarkers,
target analytes, and
degradation products.
This system of analyti-
cal procedures will
enable scientists to
measure contamina-
tion at the source,
follow the fate and
transport of residual
amounts, and assess
(continued on next page)
3
-------
The Status
(Continued)
References
human exposure.
Multianalyte immunoas-
says that can identify
several analytes are
expected to expand the
desirability of immuno-
assay technology for
environmental use.
Work in this area is
already underway at
EMSL-LV and else-
where. Other applica-
tions of immuno-
chemistry, such as
multianalyte optical
immunobiosensors and
biorefractometry, are
being developed.
Industry recently
formed the Analytical
Environmental Immuno-
chemistry Consortium
(AEIC), which is focus-
sing on performance-
based method guide-
lines, method valida-
tion, and formation of
consensus on regula-
tory and technological
issues. The National
Technology Transfer
Center (NTTC) offers a
vehicle for collaborative
studies. Cooperative
Research and Develop-
ment Agreements
(CRADAs) between
industry and the gov-
ernment can be used to
promote technology
development and
licensing of immuno-
chemical applications.
The EMSL-LV has a
Technology Transfer
Office that is able to
coordinate CRADAs for
the development of
immunochemical
methods.
Immunochemical
Methods for Environ-
mental Analysis,
J. M. Van Emon and
Mumma, R. O., eds.
ACS Symposium
Series 442, Washing-
ton, DC, 1990, 229pp.
Immunochemistry
Summit Meeting II,
C. L. Gerlach and
D. A. Fuccillo, report-
ers. September 1 -2,
1993, Las Vegas, NV.
Internal Report to
EMSL-LV.
Immunochemical
Methods for Environ-
mental Analysis,
J. M. Van Emon and
V. Lopez-Avila, Anal.
Chem., Vol. 64, No. 2,
1992.
yTic"%
I echnology
° O z
O ^upport Q
\ Project £
W
For further Information about the Immunochemistry program at the EMSL-LV,
contact:
Dr. Jeanette Van Emon
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2154
For Information about using Immunochemical methods at a Superfund or
RCRA site through the EMSL-LV Technology Support Center, contact:
Mr. Ken Brown
Technology Support Center
U.S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2270
For Information about the Technology Transfer Office at the EMSL-LV,
contact:
Mr. Eric Koglin
U. S. Environmental Protection Agency
Environmental Monitoring Systems Laboratory
P.O. Box 93478
Las Vegas, NV 89193-3478
(702) 798-2432
The Technology Support Center fact sheet series is developed by
Clare L. Gerlach, Lockheed Engineering & Sciences Company, Las Vegas
-------
United States Office cf Office of Soiic EPA 5^0.
-------
trace metals or nonvolatile organics are the contaminants antici-
pated".
SOURCES OF ERROR
Error can be introduced into the ground-water sample by casing
materials with several processes including:
a. Chemical attack of the casing material.
b. Sorption and desorption.
c. Leaching of the casing material.
d. Microbial colonization and attack (Barcelona et al., 1985)
Before proceeding further, it is necessary to define the terminol-
ogy used in this report. The terms "sorbed" or "sorption" are used
many times in the literature to refer to the processes of adsorp-
tion and absorption especially when the exact mechanism is not
known. Adsorption is defined as the adherence of atoms, ions,
or molecules of a gas or liquid called the adsorbate onto the
surface of another substance, called the adsorbent; whereas,
absorption is the penetration of one substance (absorbate) into
the innerstructure of anothercalled the absorbent. In this report,
rather than distinguishing between the processes of adsorption
and absorption, the term sorbed will be used synonymously with
both processes, unless otherwise noted. Desorption refers to
the process of removing a sorbed material from the solid on
which it is sorbed. Leaching refers to the removal or extraction
of soluble components of a material (i.e., casing material) by a
solvent (Sax and Lewis, 1987).
TABLE 1. FACTORS AFFECTING ADSORPTION
1 An increasing solubility of the solute in the liquid carrier decreases its
adsorbability. •
2 Branched chains are usually more adsorbable than straight chains An
increasing length of the chain decreases solubility
3. Substituent groups affect adsorbability.
Substituent Group Nature of Influence
Hydroxyl Generally reduces absorbability; extent of decrease
depends on structure of host molecule.
Amino Effect similar to that of hydroxyl but somewhat
greater. Many amino acids are not adsorbed to any
appreciable extent.
Carbonyl Effect varies according to host molecule, glyoxylic
are more adsorbable than acetic but similar increase
does not occur when introduced into higher fatty
acids.
Double Bonds Variable effect as with carbonyl.
Halogens Variable effect.
Sulfonic Usually decreases adsorbability.
Nitro Often increases adsorbability.
Aromatic Rings Greatly increases adsorbability.
Casing material in contact with a liquid has the potential to allow
either leaching and/or sorption. Factors influencing sorption of
organics and metals are discussed by Jones and Miller (1988)
and Masseeet al., (1981), respectively. These factors include:
1. The surface area of the casing. The greater the ratio of
casing material surface area to the volume of adsorbate the
greater the sorption potential.
2. Nature of the analyte (chemical form and concentration).
3. Characteristics of the solution. This includes factors such
as pH, dissolved material (e.g., salinity, hardness),
complexing agents, dissolved gasses (especially oxygen,
which may influence the oxidation state), suspended matter
(competitor in the sorption process), and microorganisms
(e.g., trace element take-up by algae).
4. Nature of the casing material (adsorbent). This includes
factors such as the chemical and physical properties of the
casing material.
5. External factors. These factors include temperature, con-
tact time, access of light, and occurrence of agitation.
According to Barcelona et al., (1988) considerations for select-
ing casing material should also include the subsurface geo-
chemistry and the nature and concentration of the contaminants
of interest. They also state that strength, durability, and inert-
ness of the casing material should be balanced with cost
considerations. Ford (1979) summarized factors related to the
analyte that can affect adsorption (Table 1).
4. Generally, strong ionized solutions are not as adsorbable as weakly
ionized ones; i.e., undissodated molecules are in general preferentially
adsorbed.
5. The amount of hydrolytic adsorption depends on the ability of the
hydrolysis to form an adsorbable acid or base.
6. Unless the screening action of the adsorbent pores intervene, large
molecules are more sorbable than small molecules of similar chemical
nature. This is attnbuted to more solute-adsorbent chemical bonds
being formed, making desorption more difficult.
7. Molecules with low polarity are more sorbable than highly polar ones.
(Source: Ford, 1979)
Berens and Hopfenberg (1981) conducted an investigation to
determine a correlation between diffusivity and size and shape
of the penetrant molecules. Their study indicated that as the
diameter of "spherical" penetrant molecules increased, the
diffusivity decreased exponentially. Another finding of the study
was that flattened or elongated penetrant molecules such as n-
alkanes had greater diffusivities than spherical molecules of
similar volume or molecular weight. This may indicate that
elongated molecules can move along their long axis when
diffusing through a polymer.
Reynolds and Gillham (1985) used a mathematical model to
predict the absorption of organic compounds by the different
2
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polymer materials. Curves based on their model were fit to
experimental data and showed reasonable agreement This
agreement supports their concept that uptake is the result of
absorption. They also determined that no relationship was
found between the order of absorption and readily available
parameters such as aqueous solubility or octanol/water parti-
tioning coefficient. They concluded that predicting the amount
of absorption for a particular organic compound was not pos-
sible at that time.
Gillham and O'Hannesin (1990) attempted to predict the rate of
uptake of benzene, toluene, ethylbenzene, and p-, m-, and o-
xylene onto samples SS316, PTFE, rigid PVC, flexible PVC,
polyvinylidene fluoride (PVDF), flexible PE, and FRE employing
the same model as that used by Reynolds and Gillham (1985).
Their results showed the diffusion model data fitted their experi-
mental data quite well, suggesting the sorption mechanism was
absorption into the polymer materials agreeing with the results
of Reynolds and Gillham (1985). They also determined, that for
the organic compounds used in this study, the rate of uptake
increased with increasing hydrophobicity of the organic com-
pound and varied with the physical characteristics of the poly-
mer casing material.
TYPES OF CASING MATERIALS
A variety of materials may be used for casing and screening
ground-water monitoring wells. These materials include glass
and metallic and synthetic materials. Rigid glass has the least
potential for affecting a sample and is the material of choice for
sampling organics (Pettyjohn et al., 1981). However, because
the use of glass as a casing matenal is impractical for field
applications because of its brittleness, it will not be further
considered in this report. Instead, this report will focus on the
metallic and synthetic materials most commonly used for
monitoring well construction.
Metals
Metals are often chosen as casing materials because of their
strength. Metals used for casing include SS, carbon steel,
galvanized steel, cast iron, aluminum, and copper. The various
metals used for well casings may react differently to different
compounds. Reynolds et al., (1990) conducted a study using
SS, aluminum, and galvanized steel to determine their potential
to cause problems in samples collected for analysis for haloge-
nated hydrocarbons. The metals were subjected to aqueous
solutions of 1,1,1-trichloroethane (1,1,1-TCA), 1,1,2,2-
tetrachloroethane (1,1,2,2,-TET), hexachloroethane (HCE),
bromoform (BRO), and tetrachloroethylene (PCE) for periods
up to 5 weeks. The study indicated that, of the metals used, SS
was the least reactive followed by aluminum and galvanized
steel. Stainless steel caused a 70 percent reduction of BRO and
HCE after 5 weeks. Aluminum caused over a 90 percent
reduction for all but one of the compounds while galvanized steel
showed over a 99 percent reduction for all of the compounds.
Many investigations have shown that errors may be introduced
into the water sample as a result of using metal casings. For
instance, Marsh and Lloyd (1980) determined steel-cased wells
modified the chemistry of the formation water. They state that
trace element concentrations of the ground water collected from
the wells were not representative of the aquifer conditions and
did not recommend the use of steel casing for constructing
monitoring wells. They suspected that reactions between the
ground water and the steel casing raise the pH of the water
which causes the release of metal ions into solution. Pettyjohn
et al., (1981) found metals strongly adsorb organic compounds.
For example, they claim that DDT is strongly adsorbed even by
SS. Hunkin et al., (1984) maintain that steel-cased wells are
known to add anomalously high iron and alloy levels as well as
byproducts of bacterial growth and corrosion to a sample.
Houghton and Berger (1984) discovered that samples from
steel-cased wells were enriched in cadmium (Cd), chromium
(Cr), copper (Cu), iron, manganese, and zinc (Zn) relative to
samples obtained from plastic-cased wells.
Stainless steel is one type of metal used for casing and that
appears to have a high resistance to corrosion. In fact, the U.S.
EP A (1987) states that SS is the most chemically resistant of the
ferrous materials. Two types of SS extensively used for ground-
water monitoring are stainless steel 304 (SS304) and stainless
steel 316 (SS316). These are classified as austenitic type SS
and contain approximately 18 percent chromium and 8 percent
nickel. The chemical composition of SS304 and SS316 is
identical with the exception being SS316 which contains 2-3
percent molybdenum. Brainard-Kilman (1990) indicate SS316
has improved resistance to sulfuric and saline conditions and
better resistance to stress-corrosion.
The corrosion resistance of SS is due to a passive oxide layer
which forms on the surface in oxidizing environments, this
protective layer is only a few molecules thick. It recovers quickly
even if removed by abrasion (Fletcher 1990). However, several
investigators note that SS is still susceptible to corrosion. Under
corrosive conditions, SS may release iron, chromium, or nickel
(Barcelona et al., 1988). Hewitt (1989a) found in a laboratory
study that samples of SS316 and SS304 were susceptible to
oxidation at locations near cuts and welds. When these cuts and
welds are immersed in ground water, this surface oxidation
provides active sites for sorption and also releases impurities
and major constituents. SS may be sensitive to the chloride ion,
which can cause pitting corrosion, especially over long term
exposures under acidic conditions (U.S. EPA, 1987).
Parker et al., (1989) evaluated samples of SS304 and SS316for
their potential to affect aqueous solutions of 10 organic com-
pounds. The 10 organics used in the study were RDX,
trinitrobenzene (TNB), c-1,2-DCE, t-1,2-DCE, m-nitrotoluene
(MNT), TCE, MCB, o-dichlorobenzene (ODCB),
p-dichlorobenzene (PDCB), and m-dichlorobenzene (MDCB) at
concentrations of 2 mg/L. Their study indicated the SS well
casings did not affect the concentration of any of the analytes in
solution.
Synthetic Materials
Synthetic materials used for casing evaluation include PTFE,
PVC, polypropylene (PP), polyethylene (PE), nylon, fiberglass
reinforced epoxy (FRE), and acrylonitrile butadiene styrene
(ABS). The two most commonly used synthetic casing materials
are PVC and PTFE. Very little information regarding the
suitability of FRE as a casing material is presently available in
3
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the literature; however, a 3-week dwell-time study conducted by
Cowgill (1988) indicated that FTFE revealed no detectable
quantities of the substances used in its manufacture. Hewitt
(1989a and 1989b) determined that PTFE was the material of
choice for sampling inorganic compounds whereas, Barcelona
(1985) recommends PTFE for most all monitoring applications.
PTFE is a man-made material composed of very long chains of
linked fluorocarbon units. PTFE is considered as a thermoplas-
tic with unique properties. It is very inert chemically and no
substance has been found that will dissolve this polymer (The
Merck Co. Inc. 1984). The Merck Co. Inc. (1984) reports that
nothing sticks to this polymer. This antistick property may
prevent grouts from adhering to PTFE casing and prevent the
development of an effective seal around a PTFE casing. PTFE
also has a very wide useful temperature range, -100° to
+480° F; however, for most ground-water monitoring applica-
tions these extremes of temperature would rarely be
encountered.
PTFE has a low modulus of elasticity making the screened
portion PTFE casing prone to slot compression under the weight
of the well casing above. PTFE is also very flexible and the
casing sometimes has the tendency to become "crooked" or
"snake" especially in deep boreholes. Special procedures are
then required to install the casing. Morrison (1986) and Dablow
et al., (1988) discuss different techniques used to overcome
installation problems inherent to PTFE wells. PTFE also has the
tendency to stretch thus, making PTFE cased wells susceptible
to leaks around threaded joints.
PVC casing is an attractive alternative to PTFE and SS because
it is inexpensive, durable, lightweight, has better modulus and
strength properties than PTFE, and is easy to install. However,
these characteristics alone do not justify its use as a monitoring
well casing material. The casing material must not react
significantly with the surrounding ground water, leach, sorb, or
desorb any substances that might introduce error into the
sample. Many studies have been conducted comparing PVC to
other casing materials to determine its suitability -or use in
monitoring wells.
Various compounds are added to the basic PVC polymer during
the manufacturing process of rigid PVC. These compounds
include thermal stabilizers, lubricants, fungicides, fillers, and
pigments (Boettner et al., 1981; Packham, 1971). It is pre-
sumed that the additional compounds have the potential to leach
into the ground water. Tin, found in some thermal stabilizers, is
one of the compounds suspected of leaching from PVC.
Boettner et al., (1981) found that as much as 35 ppb dimethyltin
could be leached from PVC in a 24-hour period. Other com-
pounds used as thermal stabilizers, and potential sources of
contaminants, are calcium, Zn, and antimony.
Another compound suspected of leaching from PVC casing is
residual vinyl chloride monomer (RVCM). According to Jones
and Miller (1988), 1-inch diameter Schedule 40 PVC pipe
containing 10-ppm RVCM leaches undetectable quantities (at
the 2.0-ppb sensitivity level) of vinyl chloride into stagnant water
retained in the pipe. They also report that 98 percent of the PVC
casing currently manufactured in North America contains less
than 10-ppm RVCM and most casing contains less than 1 ppm
RVCM. This implies that a 1-inch diameter pipe should leach
2.0-ppb or less RVCM. The amount of RVCM leached would
also decrease as the casing diameter increased because of the
lower specific surface. Specific surface (R) is defined as the
ratio of the surface area of the casing material in contact with the
solution, to the volume of the solution. Thus, as casing diameter
inci eases, the specific area decreases.
The NSF (1989) has established maximum permissible levels
(MPL) for many chemical substances used in the manufacturing
of PVC casing (Table 2). These levels are for substances found
in low pH extractant water following extraction procedures
described by the NSF (1989). Sara (1986) recommends the use
of NSF-tested and approved PVC formulations to reduce the
possibility of leaching RVCM, fillers, stabilizers, and plasticizers.
TABLE 2. MAXIMUM PERMISSIBLE LEVELS FOR CHEMICAL
SUBSTANCES
Substances
MPL mg/L
Action levels mg/L
Antimony
0.05
Arsenic
0.050
Cadmium
0.005
Copper
1.3
Lead
0.020
Mercury
0.002
Phenolic Substances
0.05'
Tin
0.05
Total Organic Carbon
5.0'
Total Trihalomethanes
0.10
Residual Vinyl Chloride Monomer' 3.2
2.02
' In the finished product ppm (mg/kg).
' This is an action level. If the level is exceeded, further review and/or
testing shall be initiated to identify the specific substance(s), and
acceptance or rejection shall be based on the level of specific
substances in the water.
! Additional samples shall be selected from inventory and tested to
monitor for conformance to the MPL
(Source: NSF Standard Number 14)
Common practice was to use cleaner-primers and solvent
cements to join PVC casing sections used in monitoring wells.
Cements used for joining casing sections dissolve some of the
polymer and "weld" the casing sections together. Past studies
showed a correlation between certain organic compounds
found in ground-water samples and the use of PVC solvent
cement (Boettner et al., 1981; Pettyjohn et al., 1981; Sosebee
etal.,1983; CurranandTomson, 1983). Sosebeeetal., (1983)
found high levels of tetrahydrofuran, methylethylketone,
methylisobutylketone, and cyclohexanone, the major constitu-
ents of PVC primer and adhesive, in water surrounding ce-
mented casing joints months after installation. Sosebee et al.,
(1983) determined that besides contaminating the ground-
water sample these contaminants have the potential to mask
4
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other compounds found in the ground water during laboratory
analysis. Boettner et al., (1981) found, in an experiment in which
solvent cement was used for joining PVC casing,
methylethylketone, tetrahydrofuran, and cyclohexanone leach-
ing into water supplies after more than 2 weeks of testing.
Houghton and Berger (1984) conducted a study to determine the
effects of well casing composition and sampling method on
water-sample quality. Three wells were drilled on 20-ft centers
to a depth of 60 feet and cased with PVC, ABS, and steel.
Samples collected from the wells indicated ABS-cased wells
were enriched in dissolved organic carbon by 67 percent and in
total organic carbon (TOC) by 44 percent relative to samples from
the steel-cased well. The PVC-cased well was enriched in
dissolved organic carbon and TOC by approximately 10 percent
relative to the steel-cased well. The high TOC concentrations
found in the ABS and PVC casings are suspected to have been
derived from the cement used to connect the casing sections.
Other compounds suspected of leaching from PVC and into
ground water are chloroform (CHCL) and carbon tetrachloride
(CCL ). Desrosiers and Dunnigan (1983) determined that PVC
pipe did not leach CHCI3 or CCL4 into deionized, demineralized,
organic-free water, or tap water in the absence of solvent cement
even after a 2-week dwell time.
PVC primers and adhesives should not be used for joining PVC
monitoring well casing sections. The recommended means for
joining PVC casing is to use flush-joint threaded pipe casing.
Foster (1989) provides a review of ASTM guideline F480-88A
which describes in detail the standard PVC flush-joint thread.
Junk et al., (1974) passed "organic free" water through PE, PP,
latex, and PVC tubings, and a plastic garden hose. They found
o-creosol, naphthalene, butyloctylfumarate, and butyl-
chloroacetate leaching from the PVC tubing. These contami-
nants are related to plasticizers which are added to PVC during
the manufacturing process to make it more flexible. Rigid PVC
well casing contains a much smaller quantity of plasticizer and
should be less prone to leaching contaminants (Jones and Miller,
1988).
LEACHING AND SORPTION STUDIES
Many studies have been undertaken to determine the interaction
of different casing materials with volatile organic compounds
(VOCs) and trace metals. Much of the research has been aimed
at determining whether PVC can be used as a substitute for more
expensive materials such as PTFE, FRE, and SS. A review of the
literature investigating the potential effects of assorted well
casing materials on ground-water samples is presented below.
Organic Studies
Lawrence and Tosine (1976) found that PVC was effective for
adsorbing polychlorinated biphenyls (PCB) from aqueous sew-
age solutions. They reported that the low solubility and hydro-
phobic nature of the PCBs makes them relatively easy to adsorb
from aqueous solution. Parker et al., (1989) suggest the PVC
appears to be effective only in sorbing PCBs at concentrations
close to their solubility limits.
Pettyjohn et al., (1981) discuss materials used for sampling
organic compounds. They provide a list of preferred materials for
uie in sampling organic compounds in water. Their choice in
order of preference is glass, PTFE, SS, PP, polyethylene, other
plastics and metals, and rubber. They do not indicate whether
the materials in the list were sections of rigid or flexible tubing or
what testing procedures were followed. They note that experi-
mental data on the sorption and desorbtion potential of casing
materials using varied organic compounds were not available.
Miller (1982) conducted a laboratory study in which one of the
objectives was to quantify adsorption of selected organic pollut-
ants on Schedule 40 PVC 1120, low density PE, and PP well
casing materials. These materials were exposed to six organic
pollutants and monitored for adsorption over a 6-week period.
The VOCs used, along with their initial concentrations, were BRO
(4 ppb), PCE (2 ppb), trichloroethylene (TCE) (3 ppb),
trichlorofluoromethane (2 ppb), 1,1,1-TCA (2 ppb), and 1,1,2-
trichloroethane (14 ppb). The results showed that PVC adsorbed
only PCE. The PVC adsorbed approximately 25 to 50 percent of
the PCE present. The PP and PE samples adsorbed all six of the
organics in amounts ranging from 25 to 100 percent of the
amount present.
Curran and Tomson (1983) compared the sorption potential of
PTFE, PE, PP, rigid PVC (glued and unglued), and Tygon
(flexible PVC). The procedures used in this investigation con-
sisted of pumping 20 L of organic-free water with a 0.5-ppb
naphthalene spike through each tubing at a rate of 30 mLVmin.
The tests showed that 80 to 100 percent of the naphthalene was
recovered from the water for all materials except Tygon tubing.
Tygon tubing sorbed over 50 percent of the naphthalene. PTFE
showed the least contaminant leaching of the synthetic materials
tested. They concluded that PVC can be used as a substitute for
PTFE in monitoring wells if the casing is properly washed and
rinsed with room temperature water before installation. They
also conclude that PE and PP could suitably be used as well
casings.
Barcelona et al., (1985) presented a ranking of the preferred rigid
materials based on a review of manufacturers' literature and a
poll of the scientific community. The list presented by Barcelona
et al., (1965) recommended the following casing materials in
order of decreasing preference: PTFE, SS316, SS304, PVC,
galvanized steel, and low carbon steel. Table 3 presents
recommended casing materials tabulated in Barcelona et al.,
(1985) along with specific monitoring situations.
Reynolds and Gillham (1985) conducted a laboratory study to
determine the effects of five halogenated compounds on six
polymer materials. The five compounds used in this study were
1,1,1-TCA, 1,1,2,2-TET, HCE, BRO, and PCE. The polymer
materials studied were PVC rod, PTFE tubing, nylon plate, low
density PP tubing, low density PE tubing, and latex rubber tubing.
The authors evaluated nylon plate because nylon mesh is often
used as a filter material around screened portions of wells. Latex
rubber tubing was evaluated as a material that represented
maximum absorption. The materials were tested under static
conditions to simulate water standing in the borehole. Measure-
ments were made over contact times that ran from 5 minutes to
5 weeks.
5
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TABLE 3. RECOMMENDATIONS FOR RIGID MATERIALS IN
SAMPLING APPLICATIONS
(In decreasing order of preference)
Material Recommendations
PTFE (Teflon®) Recommended for most monitoring situations
with detailed organic analytical needs, particularly
for aggressive, organic leachate impacted
hydrogeologic conditions. Virtually an ideal
material for corrosive situations where inorganic
contaminants are of interest.
Results of the study are presented in Table 4. The results show
that PVC absorbed four of the five compounds; however, the
rate of absorption was relatively slow (periods of days to weeks)
Given this slow absorption rate, they do not consider there would
be significant absorption by PVC if wells were purged and
sampled the same day. The one organic compound that was not
absorbed significantly by the PVC during the 5-week test period
was 1,1,1-TCA. The loss of BRO to PVC in this study was
approximately 43 percent after 6 weeks; whereas, Miller (1982),
in a similar experiment, indicated no losses from solution over
the same time period.
TABLE 4. TIME AT WHICH ABSORPTION REDUCED THE RELATIVE
CONCENTRATION IN SOLUTION TO 0.9
Stainless Steel 316 Recommended for most monitoring (flush
(flush threaded) threaded) situations with detailed organic
analytical needs, particularly for aggressive,
organic leachate impacted by hydrogeologic
conditions.
Stainless Steel 304
(flush threaded)
PVC (flush threaded)
other noncemented
connections, only NSF-
approved materials
for casing or potable
water applications.
May be prone to slow pitting corrosion in contact
with acidic high total dissolved solids aqueous
solutions. Corrosion products limited mainly to
Fe and possibly Cr and Ni.
Recommended for limited monitoring situations
where inorganic contaminants are of interest and
it is known that aggressive organic leachate
mixtures will not be contacted. Cemented
installations have caused documented
interferences. The potential for interaction and
interferences from PVC well casing in contact
with aggressive aqueous organic mixtures is
difficult to predict. PVC is not recommended for
detailed organic analytical schemes.
Recommended for monitonng inorganic
contaminants in corrosive, acidic inorganic
situations. May release Sn or Sb compounds
from the onginal heat stabilizers in the
formulation after long exposure.
Low Carbon Steel May be superior to PVC for exposures to
Galvanized Steel aggressive aqueous organic mixtures. These
Carbon Steel materials must be very carefully cleaned to
remove oily manufacturing residues. Corrosion is
likely in high dissolved solids acidic environment,
particularly when sulfides are present. Products
of corrosion are mainly Fe and Mn, except for
galvanized steel which may release Zn and Cd.
Weathered steel surfaces present very active
sites for trace organic and inorganic chemical
species.
(Source: Barcelona et al„ 1985)
PVC
1,1,1-TCA
1,1,2,2-TET
BRO
HCE
PCE
>5 weeks
-2 weeks
-3 days
-1 day
-1 day
PTFE
BRO
1,1,2,2-TET
1,1,1-TCA
HCE
PCE
>5 weeks
-2 weeks
-1 day
-1 day
<5 minutes
Nylon
1,1,1-TCA
1,1,2,2-TET
BRO
PCE
HCE
-6 hours
-1 hour
-30 minutes
-30 minutes
<5 minutes
PP
1,1,2,2-TET
BRO
1,1,1-TCA
HCE
PCE
-4 hours
-1 hour
-1 hour
<5 minutes
<5 minutes
PE
1,1,2,2-TET
BRO
1,1,1-TCA
HCE
PCE
-15 minutes
<5 minutes
<5 minutes
<5 minutes
<5 minutes
Latex
1,1,2,2-TET
1,1,1-TCA
BRO
PCE
HCE
Rubber <5 minutes
<5 minutes
<5 minutes
<5 minutes
<5 minutes
(Source: Reynolds and Gillham, 1985)
PTFE showed absorption of four of the five compounds tested.
There was no significant absorption of BRO over the 5-week test
period. It is noted that approximately 50 percent of the original
concentration of PCE was absorbed within an 8-hour period.
The concentration of this compound may be affected even when
the time between purging and sampling is short.
The other casing materials demonstrated significant absorption
losses within minutes to a few hours after exposure to the
organic compounds. The use of nylon, latex rubber, PP, and PE
as a well casing material will cause a significant reduction in the
concentration of the organic compounds even when the time
between purging and sampling is short. They state that agree-
ment between the model study and experimental results support
the concept that absorption of the organic compounds by the
polymers occur by sorption/dissolution of the compounds into
the polymer surface followed by diffusion into the polymer
matrix.
6
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Parker and Jenkins (1986) conducted a laboratory study to
determine if PVC casing was a suitable material for monitoring
low levels of the explosives 2,4,6-trinitrotoluene (TNT),
hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-
1,3,5,7-tetranitro 1,3,5,7-tetrzocine (HMX), and 2,4-
dinitrotoluene (DNT). Samples of PVC casing were placed in
glass |ars containing an aqueous solution of TNT, RDX, HMX,
and DNT. After80 days, the solution was tested to determine the
concentration of TNT, RDX, HMX, and DNT left in solution. After
the 80 days, the solutions containing RDX, HMX, and DNT
showed little loss, whereas TNT showed a significant loss. PVC
casing was tested under sterile and nonsterile conditions in 325-
day experiment to determine whether microbial degradation or
sorption by PVC was the cause for losses of TNT, RDX, HMX,
and DNT. Results indicated that the loss of TNT in the test was
caused by microbial activity rather than to adsorption. The
increased microbial activity may be caused by bacteria initially
present on the unsterilized PVC casing, increased surface area
for colonization provided by the PVC surface, leaching of
nutrients from the casing increasing the growth of bacteria, and
the rate of biodegradation.
Parker and Jenkins (1986) do not consider PVC casing to
significantly affect ground-water samples when monitoring for
TNT, RDX, DNT, and HMX if thetime between purging of the well
and sampling is short. They concluded PVC is an acceptable
casing material for ground-water monitoring of TNT, RDX, DNT,
and HMX.
Sykes et al., (1986) performed a laboratory study to determine
if there was a significant difference in the sorption potential
between PVC, PTFE, and SS316 when exposed to methylene
chloride (dichloromethane or DCM), 1,2-dichloroethane (1,2-
DCA), trans-1,2-dichloroethyiene (t-1,2-DCE), toluene, and
chlorobenzene (MCB). Samples of the various well casing
materials were placed in jars containing aqueous solutions of
the solvents at concentrations of approximately 100 ppb. The
concentration of each solvent was determined after 24 hours
and again after 7 days. The study concluded that there were no
statistically different chemical changes in the solutions exposed
to PVC, PTFE, and SS316 casing. Thus, it could be presumed
that PVC, PTFE, or SS316 are suitable casing materials for
monitoring DCM, 1,2-DCA, t-1,2-DCE, toluene, and MCB when
the period between well purging and sampling is less than 24
hours.
Barcelona and Helfrich (1986) conducted a field study at two
landfills to determine the effects of different casing materials on
sample quality. Wells were constructed upgradient and
downgradient of each of the two landfill sites. The wells at
Landfill 1 were constructed of PTFE, PVC, and SS304; whereas,
the wells at Landfill 2 were constructed of PVC and SS.
They observed that the downgradient SS and PTFE wells at
Landfill 1 showed higher levels of TOC than did the PVC wells.
The upgradient wells at Landfill 1 showed no significant differ-
ence among casing material type. TOC sampling at Landfill 2
showed similar results; however, no significant differences
among material types were determined either upgradient or
downgradient of the landfill.
Levels of 1,1-dichloroethane (1,1-DCA) and cis-1,2-
dichloroethylene (c-1,2-DCE) were significantly higher for the
downgradient SS wells than for PTFE and PVC cased wells at
Landfill 1. They suspect that PTFE and PVC tend to have a
greater affinity for these organic compounds than does SS.
At Landfill 2 they noted greater levels of 1,1-DCA and total
volatile halocarbons in the PVC wells than in the SS wells. They
hypothesize that the higher levels of the organic compounds
found in the water samples from the PVC cased well may be
caused by the sorptive and leaching properties of PVC which
tend to maintain a higher background level of organic com-
pounds in the ground water relative to SS. They did not suspect
the SS and PVC wells at Landfill 2 are intercepting ground water
of different quality since the wells are approximately 4 feet apart.
The authors conclude that well casing materials exert signifi-
cant, though unpredictable effects on TOC and specific VOC
determinations. Parker et al., (1989) suspect that a larger
statistical base is needed before such conclusions can be
drawn. Parker et al., (1989) also suggest the possibility that
differences in well construction methods may have had an effect
on the quality of these water samples.
Gossett and Hegg (1987) conducted a laboratory test to deter-
mine the effects of using a PVC bailer, a PTFE bailer, and an
ISCO Model 2600 portable pump on the recovery of CHCI3,
benzene, and 1,2-DCA. The effect on recovery of VOCs was
studied by varying the lift height and the casing material. The
casing materials consisted of either PVC or SS. In their
conclusion they state that either PVC or SS would be suitable for
collecting VOC samples.
Parker et al., (1989) performed a laboratory study to compare
the performance of PVC, SS304, SS316, and PTFE subjected
to aqueous solutions of RDX, trinitrobenzene (TNB),
c-1,2-DCE, t-1,2-DCE, m-nitrotoluene (MNT), TCE, MCB,
o-dichlorobenzene (ODCB), p-dichlorobenzene (PDCB), and
m-dichlorobenzene (MDCB) at concentrations of 2 mg/L. A
biocide was added to the samples to eliminate possible losses
due to biodegradation.
Prior to the experiment, they conducted a test to determine if the
casing materials were capable of leaching any compounds into
water. Samples of casing material were placed in vials contain-
ing well water and allowed to stand for 1 week. No evidence of
materials leaching from any of the casing materials was noted.
Casing samples were placed in sample jars containing an
aqueous solution of the organic compounds and sampled ini-
tially and at intervals between 1 hour and 6 weeks. Table 5
presents results after a 1 -hour, 24-hour, and 6-week dwell time.
The test results indicated that after 6 weeks PTFE had sorbed
significant amounts of all the compounds with the exception of
RDX and TNB. In the same time period, PVC showed significant
sorption of TCE, MCB, ODCB, PDCB and MDCB. In each one
of the cases where the PVC and PTFE both sorbed significant
amounts of analytes, PTFE always had the greatest sorption
rate. After 6 weeks, the SS samples exhibited no significant
sorption of the tested compounds.
At the 24-hour mark, PTFE and PVC had experienced signifi-
cant sorption of all the compounds with the exception of RDX,
TNB, and MNT. For the compounds sorbed by PTFE and PVC,
PTFE had the higher rate of uptake with the exception of c-1,2-
DCE. SS showed no significant sorption of any of the com-
7
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TABLE 5. NORMALIZED' CONCENTRATION OF ANALYTES FOR
FOUR WELL CASINGS WITH TIME
Analyte
Treatment
1 hour
24 hours
6 weeks
RDX
PTFE
1.03
1.00
0.99
PVC
1.01
0.98
1.00
SS304
0.99
1.01
0.98
SS316
1.01
1.01
1.00
TNB
PTFE
1.01
1.00
1.01
PVC
1.01
0.98
1.02
SS304
0.99
1.00
i.OO
SS316
1.02
1.01
1.02
c-1,2-DCE
PTFE
1.01
0.96|
0.79f
PVC
1.00
0.95t
0.90
SS304
0.97
1.00
0.98
SS316
0.95
1.00
0.99
t-1,2-DCE
PTFE
1.00
0.88t
0.56f
PVC
1.00
0.93f
0.83
SS304
0.95t
1.00
1.00
SS316
1.00
1.00
1.00
MNT
PTFE
1.03
0.99
0.90f
PVC
1.02
0.98
0.94
SS304
1.00
1.01
1.07
SS316
1.02
1.02
0.99
TCE
PTFE
1.00
0.85t
0.40t
PVC
1.01
0.94f
0.88f
SS304
0.96
1.01
0.99
SS316
1.00
1.00
1.00
MCB
PTFE
1.01
0.90t
0.511
PVC
1.01
0.95t
0.86|
SS3Q4
0.98
1.00
0.99
SS316
0.99
1.01
0.99
ODCB
PTFE
1.01
0.88t
0 43|
PVC
1.02
0.94f
0.86f
SS304
0.98
1.00
1.00
SS316
1.01
1.01
1.00
PDCB
PTFE
0.92t
0.77|
0.26|
PVC
0.95
0.92t
0.801"
SS304
0.911"
1.00
1.02
SS316
0.94
1.00
1.02
MDCB
PTFE
1.00
0.78f
0.26t
PVC
1.02
0.92t
0.80t
SS304
0.99
1.00
1.02
SS316
1.03
1.00
1.01
' The values given here are determined by dividing the mean
concentration of a given analyte at a given time and for a particular well
casing by the mean concentration (for the same analyte) of the control
samples taken at the same time.
r Values significantly different from control values.
(Source. Parker etal., 1989)
pounds tested. It appears that PTFE cased wells will introduce
a greater bias into ground-water samples than those cased with
PVC if the time between sampling and purging is 24 hours.
They also conducted a desorption experiment on the samples
that had sorbed organics for 6 weeks. After 3 days of testing, the
PVC and PTFE samples showed desorption of analytes sorbed
in the previous experiment. The desorption study showed that
PTFE, in general, showed a greater loss of analytes than PVC.
Jones and Miller (1988) conducted laboratory experiments to
evaluate the adsorption and leaching potential of Schedule 40
PVC (PVC-40), Schedule 80 PVC (PVC-80), ABS, SS, Teflon-
PFA, Tefion-FEP, PTFE, and Kynar-PVDF. Organic com-
pounds used in this experiment were 2,4,6-trichlorophenol
(2,4,6-TCP), 4-nitrophenol, diethyl pthalate, acenaphthene,
naphthalene, MDCB, 1,2,4-trichlorobenzene, and
hexachlorobenzene. Samples of casing material were placed
into glass vials each containing an organic compound having an
approximate initial concentration of 250 ppb.
In their first experiment, the organic compounds were mixed with
neutral pH ground water. The batches were sampled immedi-
ately and then at intervals of 1-, 3-, and 6-weeks. The results
showed that there was no appreciable change in adsorption of
the compounds after 1 week except for 2,4,6-TCP, which totally
adsorbed after 3 weeks. The results also indicate that PTFE
might be less likely to adsorb these compounds. Jones and
Miller (1988) also point out that at the concentrations used in this
study, PTFE, PVC-40, and PVC-80 exhibited very little differ-
ence in the amounts of adsorption.
In their second experiment, Jones and Miller (1988) attempted
to determine the amount of the adsorbed compounds that would
be released back into uncontaminated ground water after a 6-
week exposure time. After a 2-week period, very little release of
organic contaminants was observed. They state that only zero
to trace amounts of the sorbed contaminants were desorbed into
the noncontaminated ground water. Only PVC-80 and Teflon-
PFA desorbed naphthalene.
They repeated their adsorption and leaching experiments using
polluted ground water with a pH of 3.0. The adsorption experi-
ment showed that, with the exception of ABS casing, the casing
materials showed less adsorption at the contaminated low pH
level than at the noncontaminated neutral pH level. One
possible explanation is there could be stronger binding and
more preferential complexing of the experimental pollutants with
other pollutants in the contaminated ground water. Another,
more likely explanation, is that there is a relationship between
the extent of adsorption, pH, and pK, with a maximum adsorp-
tion occurring when the pH is approximately equal to pK. They
explain that as the pH decreases, the hydrogen ion concentra-
tion increases and the adsorption tends to decrease, suggesting
a replacement of the adsorbed compound by the more preferen-
tially adsorbed hydrogen ions.
Jones and Miller (1988) concluded there is no clear advantage
to the use of one particular well casing material over the others
for the organics used in the study. Well purging procedures,
sampling device selection and composition, and sample storage
are probably of greater influence to sample integrity and repre-
sentativeness than well casing material selection. They found
8
-------
the amount of adsorption generally correlates with the solubility
of the chemical independent of the well casing material.
Gillham and O'Hannesin (1990) conducted a laboratory study to
investigate the sorption of six monoaromatic hydrocarbons
onto/into seven casing materials. The six organic compounds
used were benzene, toluene, ethylbenzene, and p-, m-, and o-
xylene. The seven casing materials used in the evaluation were
SS316, PTFE, rigid PVC, flexible PVC, polyvinylidene fluoride
(PVDF), flexible PE, and FRE. The materials were placed in
vials containing an aqueous solution of all six organic materials.
Concentrations of the organics in the solution ranged between
1.0 and 1.4 mg/L. Sodium azide (0.05 percent), a biocide, was
added to the solution to prevent biodegradation of the organics.
The solutions were sampled 14 times from 5 minutes to 8 weeks.
Results of the study are presented in Table 6 and indicate that
SS is the most favorable casing material for sampling organics.
Stainless steel showed no significant uptake after an 8-week
exposure period; whereas, all the polymer materials adsorbed
all the organic compounds to some degree. The order of
magnitude of adsorption for the ,various polymer materials
tested was flexible PVC > PE > PTFE > PVDF > FRE > rigid PVC
(from greatest to least sorption). Flexible tubing materials
showed substantial uptake after 5 minutes of exposure. Rigid
PVC showed the lowest rate of uptake of the polymer materials.
TABLE 6. TIME INTERVAL WITHIN WHICH THE CONCENTRATION
PHASE FOR THE COMPOUND AND CASING MATERIAL BECAME
SIGNIFICANTLY DIFFERENT FROM 1.0
Time, hours
Ethyl-
Material Benzene Toluene benzene m-Xylene o-Xylene p-Xytene
SS316
>1344
PVC (rigid)
4a -96
24-48
12-24
12-24
12-24
12-24
FRE
24-48
3-6
0.1-1.0
3-6
3-6
3-6
PVDF
24-48
3-6
1 -3
1 -3
0.1-1.0
1 -3
PTFE
24-48
3-6
1 -3
3-6
6-12
1 -3
PE
0-0.1
0-0.1
0-0.1
0-0.1
0-0.1
0-0.1
PVC (flexible) 0-0.1
0-0.1
0-0.1
0-0.1
0-0.1
0-0.1
(Source: Gillham and O'Hannesin, 1996)
Gillham and O'Hannesin (1990) conclude'all of the polymer
materials tested, except flexible PVC and PE, are suitable
casing materials in monitoring wells. This is based on selection
of an appropriate casing diameter and an appropriate interval
between purging and sampling. They state rigid PVC is the most
favorable polymer material for casing in monitoring wells.
Reynolds et al., (1990) conducted laboratory tests to evaluate
the effects of five halogenated hydrocarbons on several casing
materials. The halogenated hydrocarbons and casing materials
used in the experiment were identical to those used by Reynolds
and Gillham (1985) with the addition of glass, SS316, aluminum,
and galvanized sheet metal to the casing materials.
The results indicated borosilicate glass was the least likely of the
10 materials to affect the samples. The results also showed that
all of the metals had the potential to sort compounds from
solution. The order of the compound sorption rate for the metals
was galvanized steel > aluminum > SS (greatest to least
sorption).
Results of the sorption experiments indicated rigid PVC was
preferable to PTFE for sampling low concentrations of haloge-
nated hydrocarbons. The compound sorption rates, from great-
est to least sorption, are latex > low density PE > PP > nylon >
PTFE > rigid PVC. The rates of compound loss, from greatest
to least loss, are PCE > HCE > 1,1,1 -TCA > BRO >1,1,2,2-TET.
It should be noted the inequalities shown above are not neces-
sarily significant. For example, the rates between PTFE and
rigid PVC are not significant and the same is true for nylon and
PP. Their study showed flexible polymer tubing is likely to have
greater sorption rates than rigid polymers which is in agreement
with Barcelona et al., (1985). They also found evidence that
there is a correlation between compound solubility and sorption,
substantiating earlier studies. Reynolds et al., (1990) found
diffusivity decreased as mean molecular diameter increased
which agrees with a study performed by Berens and Hopfenberg
(1982), based on polymeric diffusivity tests.
They suggest the use of PTFE in monitoring wells in areas where
higher concentrations might be encountered, for instance near
a solvent spill. Their study showed a polymer exposed to high
concentrations of an organic compound that is agood solvent for
the polymer, that the polymer will absorb large quantities of the
solvent and swell. However, it is difficult to predict the swelling
power of various solvents. As an example, rigid PVC can absorb
over 800 percent of its weight in DCM but only 1 percent of CCL4.
Schmidt (1987), however, found no swelling or distortion of rigid
PVC casing or screen when exposed to various gasolines for 6.5
months.
Taylor and Parker (1990) visually examined PVC, PTFE,
SS304, and SS316 with a scanning electron microscope (SEM)
to determine how they were affected by long-term exposures (1
week to 6 months) to organic compounds. Organics used in this
test were PDCB, ODCB, toluene, and PCE at concentrations of
17.3,33.5,138, and 35.0 mg/L, respectively (approximately 25
percent of their solubilities in water).
SEM examinations showed no obvious surface structure
changes for any of the materials exposed to the different
concentrated organic aqueous solutions. They caution, how-
ever, that this study cannot be extended to instances where
casing materials are exposed to pure organic solvents. They did
not report the amount of compound sorted by the different
casing materials.
Inorganic Studies
Massee et al., (1981) studied the sorption of silver (Ag), arsenic
(As), Cd, selenium (Se), and Zn from distilled water and artificial
sea water by borosilicate glass, high-pressure PE, and PTFE
containers. The effect of specific surface (R in cm'), i.e., the
ratio of the surface area of the material in contact with the
solution, to the volume of the solution, was also studied. Metals
were added to the distilled and artificial sea water. The pH levels
of the aqueous solutions used were 1, 2, 4, and 8.5. Water
9
-------
samples were tested at intervals ranging between 1 minute and
28 days. Losses of As and Se were insignificant for all the
treatments. At pH levels of 1 and 2, no significant sorption from
either distilled water or artificial sea water was observed for any
of the containers or metals used in this study. Test results of the
sorption of Ag, Cd, and Zn from distilled water and sea water are
presented in Tables 7 and 8, respectively.
The results showed PTFE sorbed substantial amounts of Ag,
Cd, Zn, and the amounts sorbed were dependent on the pH and
salinity of the solutions. Specific surface was found to have a
significant effect on the sorption of metals by PTFE. For
example, at the end of 28 days the loss of Ag to PTFE with R =
5.5 cm-1 was almost 4 times higher than for R = 1.0 cm-'.
Massee et al., (1981) concluded that sorption losses are difficult
to predict because the behavior of trace elements depends on
a variety of factors such as trace element concentration, mate-
rial, pH, and salinity. They noted that a reduction in contact time,
specific surface, and acidification may reduce sorption losses.
Miller (1982) conducted a study to determine the potential of
PVC, PE, arid PP to sorb and release Cr(VI) and lead (Pb) when
in a Cr(VI)-Pb solution and in a solution of these two metals
along with the following organics; BRO, PCE, TCE,
trichlorofluromethane, 1,1,1-TCA, and 1,1,2-trichloroethane.
Tables 9 and 10, respectively, present the results for the Cr(VI)
and Pb adsorption and leaching studies. The results showed
that none of the materials tested adsorbed Cr(VI) to any signifi-
cant extent when in a solution with Pb. When in a solution with
Pb and 6 other organics, 25 percent of Cr(VI) was adsorbed by
the 3 casing materials. No leaching of Cr(VI) was observed from
any of the materials either in the metals only or metals and
organics solutions. Seventy-five percent of the Pb was
adsorbed by PVC when in a solution with Cr(VI) and also when
in a solution of Cr(VI) and the six organics. PE and PP showed
about 50 percent adsorption of Pb when in a solution with Cr(VI).
The casing materials did not leach any Pb when in a solution with
Cr(VI); however, when in a solution with Cr(VI) and 6 organics,
the 3 casing materials leached approximately 50 percent of the
Pb initially adsorbed. In his study, Miller found that PVC
TABLE 7. SORPTION BEHAVIOR OF SILVER, CADMIUM, AND ZINC IN
DISTILLED WATER
Borosilicate
Material PE Glass PTFE
pH
4
8.5
4
8.5
4
8.5
R(cm')
1.4 3.4
1.0 3.4
1.0
4.2
1.0 4.2
1.4 5.5
1.0 5.5
Metal
Contract
Time
Sorption (%)
Ag
1 hour
10
15
25 36
4
9
21
*
•
10
1 day
25
66
72 49
32
18
26
48
4
6
5
25
28 days
96
100 59 100
82
80
72
63
15
55
22
28
Cd
1 hour
*
*
7 69
•
6
26
•
7
38
1 day
•
* 47
•
10
32
•
10
48
28 days
*
•
* 31
*
•
*
•
15
46
Zn
1 hour
•
*
* 65
23
22
*
#
3
16
1 day
•
*
8 56
*
26
22
*
•
5
27
28 days
•
»
12 56
6
20
'Denotes a loss smaller than 3 percent.
(Source: Massee etaL, 1981)
TABLE 8. SORPTION BEHAVIOR OF SILVER, CADMIUM, AND ZINC IN
ARTIFICIAL SEA WATER
Material
PE
Borosilicate
Glass
PTFE
PH
4
8.5
4
8.5
4
8.5
R(crTv')
1.4 3.4
1.0 3.4
1.0 4.2
1.0 4.2
1.4 5.5
1.0 5.5
Metal
Contract
Time
Sorption (%)
Ag
1 hour
t *
6 5
* •
3 3
i t
* 4
1 day
• *
24 28
4 4
6 9
• •
6 12
28 days
« »
46 78
82 71
40 67
• «
27 37
Cd
1 hour
1 day
28 days
* *
• «
14 36
Zn
1 hour
1 day
9 31
5 26
• •
4 *
* «
• •
28 days
~ *
• t
20 19
4 9
5 *
t •
'Denotes a loss smaller than 3 percent.
(Source: Massee at al., 1981)
10
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TABLE 9. TRENDS OF CHROMIUM (VI) EXPOSED TO SYNTHETIC
WELL CASING (COMPARED TO CONTROLS)
Adsorption Adsorption/Leaching
Casing
Material
Metals
Only
Metals and
Organics
Metals
Only
Metals and
Organics
PVC
No adsorption
Slight (25%)
adsorption
No leaching
No leaching
PE
No adsorption
Slight (25%)
adsorption
No leaching
No leaching
PP
No adsorption
Slight (25%)
adsorption
No leaching
No leaching
(Source: Miller, 1982)
TABLE 10. TRENDS OF LEAD EXPOSED TO SYNTHETIC WELL
CASING (COMPARED TO CONTROL)
Adsorption Adsorption/Leaching
Casing
Material
Metals
Only
Metals and
Organics
Metals
Only
Metals and
Organics
PVC
Mostly (75%)
adsorbed
Mostly (75%)
absorbed
No leaching
Mostly (75%)
absorbed
PE
Moderate (50%)
adsorption
(delayed)
Moderate (50%)
adsorption
No leaching
Mostly (75%)
adsorbed
PP
Moderate (50%)
adsorption
(delayed)
Slight (25%)
adsorption
No leaching
Mostly (75%)
adsorbed
(Source: Miller 1982)
generally causes fewer monitoring interferences with VOCs
than PE and PP and that PVC adsorbed and released organic
pollutants at a slower rate relative to PE and PP.
Hewitt (1989a) examined the potential of PVC, PTFE, SS304,
and SS316 to sorb and leach As, Cd, Cr, and Pb when exposed
to ground water. The pH, TOC, and metal concentrations of the
solution were varied and samples, taken between 0.5 and 72
hours. The study showed that PTFE had the least-active
surface and showed an affinity only to Pb (10 percent sorption
after 72 hours). PVC and SS leached and sorbed some of the
metals tested. PVC was a source for Cd and sorbed Pb (26
percent sorption after 72 hours). The SSs were the most active
of the materials tested. SS304 was a source of Cd and sorbed
As and Pb. SS316 was also a source of Cd and sorbed As, Cd,
and Pb. The study showed results were affected by the solution
variables (i.e., pH, TOC, and concentration). SS304 and SS316
showed evidence of corrosion near cuts and welds which may
provide active sites for sorption and release of contaminants
Hewitt (1989a) concludes PTFE is the best material for monitor-
ing the metals used in this study whereas, SSs are not suitable.
He states that although PVC was affected by Cd and Pb it should
still be considered as a useful casing material based on econom-
ics, and that when the time between purging and sampling is less
than 24 hours, the effects of Cd and Pb on PVC may be of less
concern.
Hewitt (1989b) conducted a study to determine the amounts of
barium, Cd, Cr, Pb, Cu, As, Hg, Se, and Ag leached from PTFE,
PVC, SS304, and SS316 in ground water. Table 11 summarizes
the results of the investigation. Results indicate that PTFE was
the only material tested not to leach any metals into the ground-
water solution. PTFE, however, did show atrend to sorb Cu with
time. PVC and SS316 showed a tendency to leach Cd; in
addition, these two materials, along with SS304, sorbed Pb.
PVC was also shown to leach Cr and provide sorption sites for
Cu. SS316 significantly increased the concentration of Ba and
Cu in the ground-water solution. SS304 consistently contrib-
uted Cr with time to the ground-water solution. None of the well
casing materials contributed significant levels of As, Hg, Ag, or
Se to the ground water.
TABLE 11. SUMMARY OF RESULTS
Ba
Cd
Cr
Pb
Materials that leached
>1% of the EPA
drinking water quality
level in ground-water
solutions
SS316
PVC
SS316
PVC
SS304
SS316
PVC
SS304
PVC
SS316
Materials that showed
the highest average
overall amount of
analyte leached
SS316
SS316
SS304
SS304
'Does not apply
(Source: Hewitt 1989b)
Hewitt (1989b) concludes PTFE is the best casing material
when testing for trace metals while SS should be avoided. He
also states PVC is an appropriate second choice because its
influence on metal analytes appears to be predictable and small.
Casing Material Cost Comparison
A consideration when installing monitoring wells is cost. Costs
to be considered in the installation of monitoring wells are cost
of construction materials, drilling costs, and expected life (re-
placement costs) of the casing material. Table 12 presents a
cost comparison among five casing materials: PVC, SS304,
SS316, PTFE, and FRE. The prices shown were obtained from
Brainard-Kilman (1990) with the exception of the FRE casing,
11
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TABLE 12. CASING MATERIAL COST COMPARISON
Prices refleci the cos* often 10-ft 'ong by 2-in diameter casing sections, a
5-ft long 0.010-in slottec screen, and a bottom plug.
Casing Matenal Price
PVC* S 179 50
FRE" 966,00
SS304 1,205.00
SS316 1,896.00
PTFE 3,293 50
' Schedule 40 PVC
" Low flow screen
whose price was provided by ENCO (1989). The cost estimates
are for ten 10-feet sections (100 feet) of 2-inch threaded casing,
5 feet of 0.010-inch slotted screen, and a bottom plug.
The cost of materials for 1 PTFE well is approximately 18 times
greater than 1 constructed on PVC (Table 12). At first glance,
PVC, by far, is the most economical matenal for constructing
monitoring wells. However, if drilling and material (bentonite,
cement, sand, etc.) costs are considered, the percent difference
in cost between PVC wells and wells constructed of SS, FRE, or
PTFE is reduced.
For example, assume that the cost of installing, materials, and
completing a 100-feet deep monitoring well (exclusive of casing
material costs) in unconsolidated material is $5,000. When the
cost of casing material is added to the drilling and materials
costs, a PVC-casea well costs $5,179.50 and an SS316-cased
well $6,896.00. When drilling and materials costs are consid-
ered, a PVC-cased well costs approximately 25 percent less
than a SS316-cased well. However, when drilling and materials
costs are not taken into account, PVC casing looks especially
attractive since it is approximately 90 percent less expensive
than SS316 casing. In this case, a SS316-cased well may be
considered to be cost effective especially if organics are ex-
pected to be sampled. Thus, the significance of the "cost of
casing materials versus ground water-casing interaction" issue
is reduced.
CONCLUSIONS
All aspects of a ground-water sampling program have the
potential to introduce error to a ground-water sample. Interac-
tion between monitoring well casing materials and ground
water is only one of the ways in which error may be introduced
in a sampling program. Presently, there are a variety of
materials available for fabricating monitoring wells. The poten-
tial for these casing materials to interact with ground water has
found to be affected by many factors, including pH and compo-
sition of the ground water and the casing-ground water contact
time. The complex and varied nature of ground water makes it
very difficult to predict the sorption and leaching potential of the
various casing materials. Consequently, the selection of the
proper casing material for a particular monitoring application is
difficult. This is evidenced by the lack of agreement among
researchers on which is the "best" material. The problem is
compounded by the inconclusive and incomplete results of
laboratory studies on the effects of rigid well casing materials
with inorganic or organic dissolved species.
Many of the experiments examined the effects of time on the
sorption and leaching potential of the various casing materials.
The experiments were usually run under laboratory conditions
in which distilled or "organic free" water was used and casing
materials were subject to contaminants for periods ranging from
minutes to months. These experiments, in general, indicate a
trend for the materials to be more reactive with the aqueous
solutions with time. Experiments showed if the time between
well purging and sampling is relatively short, some of the more
sorptive materials could be used without significantly affecting
sample quality.
The selection of appropriate materials for monitoring well casing
at a particular site must take into account the site hydrogeology
and several general requirements. These general requirements
for the screens and casing of wells that are used for ground-
water monitoring are the following:
1. Depth to zones being monitored and total depth of well must
be considered.
2. The geochemistry of the geologic materials over the entire
interval in which the well is to be cased and screened must
be taken into account.
3. The wells must be chemically resistant to naturally occurring
waters.
4. The well materials must be chemically resistant to any
contaminants that are present in any and all contaminated
zones of the aquifer or aquifers being monitored.
5. The strength of the materials must be physically strong
enough to withstand all compressive and tensile stresses
that are expected during the construction and operation of
the monitoring well over the expected lifetime.
6. Installation and completion into the borehole during
construction of the monitoring well must be relatively easy.
7. The well materials must be chemically resistant to any
anticipated treatments which are strongly corrosive or
oxidizing.
It may be necessary to conduct site-specific, comparative per-
formance studies to justify preference for a particular well casing
or screening material over another.
12
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Boettner, E. A., Ball, G. L., Hollingsworth, Z., and Aquino, R.,
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Berens, A. R. and Hopfenberg, H. B., 1982. "Diffusion of Organic
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Cowgill, U. M., 1988. The Chemical Composition of Leachate
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Chloroform and Carbon Tetrachloride from Rigid PVC Pipe and
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ENCO.EMC, Price List, September, 1989, Austin, TX.
Fletcher, J. R. "Stainless Steels," Engineering, November,
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Ford, D. L., 1979. "Current State of the Art Activated Carbon
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RSKERL, Ada, OK.
Foster, S., 1989. "Flush-Joint Threads Find a Home," Ground
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Gillham, R. W. and O'Hannesin, S. F. 1990. "Sorption of
Aromatic Hydrocarbons by Materials Used in Construction of
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Gossett, R. E. and Hegg, R. O., 1987. "Comparison of Three
Sampling Devices for Measuring Volatile Organics in
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Hewitt, A. D., 1989a. "Influence of Well Casing Composition on
Trace Metals in Ground Water," Special Report 89-9, USA Cold
Regions Research and Engineering Laboratory, Hanover, NH.
Hewitt, A. D., 1989b. "Leaching of Metal Pollutants from Four
Well Casings Used for Ground-Water Monitoring," Special
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Houghton, R. L. and Berger, M. L., 1984. "Effects of Well-Casing
Composition and Sampling Method on Apparent Quality of
Ground Water," Proceedings of the Fourth National Symposium
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Hunkin, G. G., Reed, T. A., and Brand, G. N., 1984. "Some
Observations on Field Experiences with Monitor Wells," Ground
Water Monitoring Review, Vol. 4, No. 1 pp. 43-45.
Jones J. N. and Miller, G. D., 1988. "Adsorption of Selected
Organic Contaminants onto Possible Well Casing Materials,"
Ground-Water Contamination: Field Methods. ASTM STP 963,
A. G. Collins and A. I. Johnson, Eds., American Society for
Testing and Materials, Philadelphia, PA. pp. 185-198.
Junk, G. A., Svec, H. J., Vick, R. D., and Avery, M. J. 1974.
"Contamination of Water by Synthetic Polymer Tubes,"
Environmental Science and Technology, Vol 8, No, 13, pp 1100-
1106.
Lawrence, J. and Tosine, H. M, 1976. "Adsorption of
Polychlorinated Biphenyls from Aqueous Solutions and
Sewage," Environmental Science and Technology, Vol. 10, No.
4, pp. 381-383.
The Merck Index 1984. Tenth Edition, Merck and Co., Inc.,
Rahway, NJ.
Marsh, J. M. and Lloyd J. W., 1980. "Details of Hydrochemical
Variations in Flowing Wells," Ground Water, Vol. 18, No. 4, pp.
366-373.
Massee, R., Maessen, F. J. M. J., and De Goeij, J. J. M., 1981.
"Losses of Silver, Arsenic, Cadmium, Selenium, and Zinc
Traces from Distilled Water and Artificial Sea-Water by Sorption
13
-------
on Various Container Surfaces," Analytica Chimica Acta, Vol
127. pp. 181-193.
Miller, G. D . 1982. "Uptake and Release of Lead, Chromium,
and Trace Level Volatile Organics Exposed to Synthetic Well
Casings," Aquifer Restoration and Ground Water
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on Aquifer Restoration and Ground Water Monitoring, May 26-
28, National Water Well Association.
Morrison, R. D., 1986. "The New Monitoring Well,'' Ground
Water Age, April, pp. 19-23.
National Sanitation Foundation, 1989. Standard Number 14,
Plastics Piping Corronents and Related Materials, Ann Arbor,
Ml.
Packham, R. F., 1971. "The Leaching of Toxic Stabilizers From
Unplasticized PVC Water Pipe: Part I - A Critical Study of
Laboratory Test Procedures," Water Treatment and
Examination, Vol. 20, No. 2, pp. 152-164.
Parker, L. V. and Jenkins, T. F., 1986. "Suitability of Polyvinyl
Chloride Well Casings for Monitoring Munitions in Ground
Water," Ground Water Monitoring Review, Summer, pp. 92-98.
Parker, L. V., Jenkins T. F., and Black, P. B., 1989. "Evaluation
of Four Well Casing Materials for Monitoring Selected Trace
Level Organics in Ground Water," CRREL Report 89-18, U.S.
Army Engineer Cold Regions Research and Engineering
Laboratory, Hanover, NH.
Pettyjohn, W. W., Dunlap, W. J., Cosby, R., and Keeley, J. W.,
1981. "Sampling Ground Water for Organic Contaminants,"
Ground Water, Vol. 19, No. 2, pp. 180-189.
Reynolds G. W. and Gillham, R. W., 1985. "Absorption of
Halogenated Organic Compounds by Polymer Materials
Commonly Used in Ground Water Monitors," In Proceedings
Second Canadian/American Conference on Hydrogeology,
Hazardous Waste in Ground Water: A Soluble Dilemma, Banff,
AB, National Water Well Association, June 25-29, pp. 125-132.
Reynolds, G. W., Hoff, J. T„ and Gillham, R. W. 1990. "Sampling
Bias Caused by Materials Used to Monitor Halocarbons in
Groundwater," Environ. Sci. Technol., Vol. 24, No 1. pp 135-
142.
Sara, M. N., 1986. "A review of Materials Used in Monitoring and
Monitoring Well Construction," In The Proceedings of the Sixth
National Symposium and Exposition on Aquifer Restoration and
Ground Water Monitoring, National Water Well Association.
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Chemical Dictionary, Eleventh Edition, Van Nostrand Reinhold
Co. Inc., New York, NY.
Schmidt, G. W., 1987. "The use of PVC Casing and Screen in
the Presence of Gasolines on the Ground Water," Ground Water
Monitoring Review, Vol. 7, No. 2, pp. 94-95.
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Fisher, C. R., 1983. "Contamination of Groundwater Samples
with Poly (Vinyl Chloride) Adhesives and Poly (Vinyl Chloride)
Primer from Monitor Wells," Hazardous and Industrial Solid
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Conway and W. P. Gulledge, Eds., American Society for Testing
and Materials, pp. 38-50.
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"Sorption of Organics by Monitoring Well Construction
Materials," Ground Water Monitoring Review, Vol. 6, No. 4, pp.
44-47.
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Casing Pipe Exposed to High Concentrations of Organics in
Aqueous Solution," Special Report 90-7, USA Cold Regions
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14
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ABBREVIATIONS
1,1-DCA
1,1-Dichloroethane
ODCB
o-Dichlorobenzene
1,1,1-TCA
1,1,1-Trichloroethane
P-
Para
1,1,2,2-TET 1,2,2,2-T etrachlorethane
Pb
Lead
1,2-DCA
1,2-Dichloroethane
PCB
Polychlorinated biphenyl
2,4,6-TCP
2,4,6-Trichlorophenol
PCE
Tetrachloroethylene
ALS
Acrylonitrile butadiene styrene
PDCB
p-Dichlorobenzene
Ag
Silver
PE
Polyethylene
As
Arsenic
PH
Hydrogen ion concentration of the solution
ASTM
American Society for Testing and Materials
pK
Log dissociation constant
BRO
Bromoform
PP
Polypropylene
c-1,2-DCE
cis-1,2-Dichloroethylene
PPb
Parts per billion (by weight)
CC1.
Carbon tetrachloride
ppm
Parts per million (by weight)
Cd
Cadmium
PTFE
Polytetrafluoroethylene (Teflon®)
CHCL
Chloroform
PVC
Polyvinylchloride
Cr
Chromium
RCRA
Resource Conservation and Recovery Act
Cu
Copper
RDX
Hexahydro-1,3,5,7-trinitro-1,3,5-triazine
DCM
Methylene chloride (dichloromethane)
RVCM
Residual vinyl chloride monomer
DNT
2,4-Dinitrotoluene
Se
Selenium
EMSL-LV
Environmental Monitoring Systems Laboratory-
SEM
Scanning electron microscope
Las Vegas
SS
Stainless steel
FRF
Fiberglass reinforced epoxy
SS304
Stainless steel 304
HCE
Hexachloroethane
SS316
Stainless steel 316
Hg
Mercury
t-1,2-DCE
trans-1,2-Dichloroethylene
HMX
Octabydro-1,2,5,7-tetranitro 1,3,5,7-tetrazocine
TCE
Trichloroethylene
m-
Meta
TEGD
Technical Enforcement Guidance Document
MCB
Chlorobenzene
TNB
Trinitrobenzene
MDCB
m-Dichlorobenzene
TNT
2,4,6-T rinitrotoluene
MNT
m-Nitrotoluene
TOC
Total organic carbon
MPL
Maximum permissible levels
U.S. EPA
U.S. Environmental Protection Agency
NSF
National Sanitation Foundation
VOC
Volatile organic compound
0-
Ortho
Zn
Zinc
15
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United States Office of Office ct Scuc EPA 5
-------
Each Superfund site has unique geologic, hydrologic, biologic
and chemical conditions that may influence the type and mag-
nitude of potential sample errors. This paper provides an
overview of sample error; types of error potentially important at
each site must be evaluated on an individual basis. Further-
more, while this paper will remain static, the conduct of site
investigations will be in a constant state of flux as new technol-
ogy is developed and as the understanding of contaminant
transport and fate and the sampling process is improved. As a
result, sources of sampling error described herein may be
resolved through the application of new technology and meth-
ods while new sources of error are likely to be identified.
MONITORING WELL DESIGN
The design of ground-water monitoring installations must be
consistent with geologic, hydrologic, and hydrochemical condi-
tions to obtain representative ground-water samples. Important
aspects of monitoring well design include length of well intake
interval, design of the filter pack and screen, design and instal-
lation of borehole seals, and well location.
Intake Length
The length and location of well intakes have important effects on
the degree with which samples represent ground-water condi-
tions. Long well intakes (long screens) are open to a large
vertical interval and therefore are more likely to provide samples
that are a composite of the ground water adjacent to the entire
intake. Conversely, short intakes (short screens) may be open
to a single strata or zone of contamination and are more likely to
provide samples that represent specific depth intervals. Wells
that are screened over more than one depth interval (multi-
screened wells), regardless of their screen lengths, may impact
ground-water conditions and samples in much the same way as
long-screened wells.
Long-screened wells have been suggested as being more cost
effective in detection monitoring than several short-screened
wells because they sample greater vertical sections of aquifers
(Giddings, 1986). However, pumping-induced vertical flow in
wells with long screens can impact ground-water flow and
contaminant concentrations near the well (Kaleris, 1989). In
addition, when ground-water contamination is vertically strati-
fied, composite samples collected from a long-screened well
represent some sort of average of concentrations adjacent to
the screen, and provide little information about the concentra-
tions in individual strata. In particular, in cases where contami-
nants may be of low concentration and restricted to thin zones,
long-screened wells may lead to dilution of the contaminants to
the point where they may be difficult to detect (Cohen and
Rabold, 1987). Likewise, long-screen wells intersecting con-
taminants of differing densities may allow density-driven mixing
within the well bore and subsequent dilution of contaminant
concentrations (Robin and Gillham, 1987). The use of inflatable
packers to isolate specific zones within a long screen may not be
an effective solution because ground water may flow vertically
through the filter pack from other zones in response to the
reduced hydraulic head in the packed-off zone during sampling.
Vertical head gradients in aquifers near long-screened wells
may lead to error in two ways: (1) if contaminants are moving
through a zone with low hydraulic head, cleaner water moving
from zones of higher head may dilute the contaminants, leading
to detection of artificially low concentrations, and, (2) if higher
concentrations of contaminants are moving through a zona of
high hydraulic head, cross-contamination between water-bear-
ing zones may occur via me well bore (Mcllvrida and Rector.
1988). These workers describe a case history in which two
aquifer zones were identified at a site, with only the top zone
contaminated with VOCs. Wells screened only in the contami-
nated zone resulted in detection of VOCs in the few hundred |ig/
L range while samples collected from long-screened wells open
to both intervals showed no VOC contamination. A numerical
flow model of a long-screened well developed by Reilly et al.
(1989) demonstrated that very low head gradients can lead to
substantial cross-flow within long-screened wells. At srtes
where delineation of vertical hydraulic and concentration gradi-
ents is important, errors can be reduced by utilizing a system of
nested short-screened wells that can more accurately charac-
terize the contaminant distribution.
Multilevel sampling devices provide an alternative monitoring
technique in situations where vertical head gradients are impor-
tant or where contamination is vertically stratified. These
devices can be installed in such a way that individual zones can
be sampled separately without vertical movement of ground
water or contaminants between zones. Using a multilevel
device. Smith et a I. (1987) detected a zone containing nitrite
concentrations over 10 mg/L that had been previously undetec-
ted by observation wells with two-foot screens. The samples
from the multilevel sampler also detected large vertical gradi-
ents in electrical conductivity (EC) and chloride that were not
detected with the monitoring wells.
Residential and municipal water-supply wells that are often
used during early phases of Rl programs are generally con-
structed with long screens, therefore concentrations of contami-
nants in samples collected from these wells may not represent
ambient ground-water concentrations. When defining human
receptors this may not be an issue because the overall quality
of ground-water extracted from water-supply wells may not
reflect the quality of water in individual strata. In these cases,
dilution may reduce concentrations of contaminants to within
health-based standards. However, gross errors may be intro-
duced into the analysis if these concentrations are used for
detailed delineation of the geometry and concentrations of
contaminant plumes or detection of contaminants at very low
concentrations.
To mitigate hazards, waste management options at Superfund
sites may include remediation of contaminated ground water by
pumping and treatment. Long-screen wells are often the most
effective for extraction of ground water because they are hy-
draulically more efficient than wells with short screens. How-
ever, because accurate ground-water contaminant concentra-
tions cannot be determined from these wells it may be neces-
sary to install separate wells for monitoring the progress of
ground-water extraction and treatment.
Filter Pack and Well Intake
Suspended solids that originate from drilling activities or are
mobilized from the formation during development, purging, or
sampling may disrupt hydrochemical equilibrium during sample
collection and shipment. A properly designed combination of
2
-------
filter pack and well intake provides an efficient hydraulic connec-
tion to a water-bearing zone and minimizes the suspended
solids content of sampled water. However, to be most effective,
filter pack and well intake design must be based on the sedi-
ments encountered in each borehole. Inadequate well perfor-
mance resulting from application of a generic well design may
lead to incomplete well development and high suspended solids
content in samples. Descriptions of the methods of filter pack
and intake design can be found in Oriscoll (1986) and Aller et al.
(1989).
Artificial filter packs should be composed of a chemically-inert
material so as to reduce the potential for chemical alteration of
ground water near the welt. Clean silica (quartz) sand is
generally recommended and widely used because it is
nonreactive under most ground-water conditions. Other types
of materials may induce chemical changes. For example, filter
pack materials containing calcium carbonate, either as a pri-
mary component or as a contaminant, may raise the pH of water
that it contacts and lead to precipitation of dissolved constituents
(Aller et al., 1989).
The use of a tremie pipe to install f ilter pack materials minimizes
the potential for introducing sample error to this phase of well
construction. Dropping filter pack materials directly into an
uncased borehole may lead to cross-contamination by mobiliz-
ing sediments or ground water between depth intervals. Fur-
thermore, installation of filter pack materials by methods which
introduce water to the borehole may modify hydrochemistry to
an unknown extent or add contaminants to the sampling zone.
Water-based methods may also lead to cross-contamination
within the borehole.
Borehole Seals
Borehole seals, generally composed of expandable bentonite or
cement grout, are well-known as potential sources of sampling
error. The expandable bentonite clay used in many seals has
high ion exchange capacity which may alter major ion composi-
tion of water(Gillham et al., 1983) or concentrations of contami-
nants that form complexes with these ions (Herzog et al., 1991).
The effects of these reactions are seldom revealed by measure-
ment of field parameters and normally-conducted analyses, but
in cases of extreme sodium bentonite contamination may be
seen as abnormally high sodium concentrations.
Cement grout can also significantly influence ground water
chem istry, particularly if the grout doesn't set property. Contam i-
nation by grout seals, which generally results from its calcium
carbonate content and high alkalinity, may be identified by
elevated calcium concentrations, pH (generally over 10 pH
units), EC, and alkalinity (Barcelona and Helfrich, 1986). These
workers found that cement contamination of several wells
persisted for over 18 months after well completion and was not
reduced by ten redevelopment efforts. Barcelona et al. (1988a)
indicate that solution chemistry and the distribution of chemical
species can be impacted by cement contamination although
these impacts have not been quantified to date. In low-perme-
ability sediments, the impacts of grout materials may be much
greater due to insufficient flushing of the installation by moving
ground water.
Contamination from borehole seals can be minimized by sepa-
rating the seals from sampling zones by fine-grained transition
sand, estimating the volume of seal material required before
installation to more easily detect bridging problems during
emplacement, and by allowing sufficient time for the seals to set.
In addition, cement grout can be isolated from sampling zones
by installation of a bentonite seal. Error can also be reduced by
installing boreholes seals with a tremie pipe. Dropping seal
materials directly into an uncased borehole may lead to cross-
contamination by mobilizing sediments or ground water be-
tween depth intervals, or may contaminate sampling zones if the
seal materials are dropped past the sampling zone depth.
Furthermore, installation of seal materials by methods which
introduce water to the borehole may modify hydrochemistry to
an unknown extent or introduce contaminants to the sampling
zone. Water-based methods may also lead to cross-conlamina-
tion within the borehole.
Well Location
The location of monitoring wells with respect to ground-water
contaminant plumes is important to the accurate depiction of
contaminant movement and concentration distribution, espe-
cially in areas where concentration gradients are large. A
discussion of optimum well placement is beyond the scope of
this document, but aspects of this topic can be found in the works
of Keith et al. (1983), Meyer and Brill (1988), Scheibe and
Lettenmaier (1989), Spruill and Candela(1990), and Andricevic
and Foufoula-Georgiou (1991). These investigators discuss
various aspects of monitoring well network design and how
monitoring well coverage of the area under investigation relates
to accurate quantification of spatial variation in hydrochemical
parameters. Generally implied within network design is the
reduction in error associated with delineating spatial variation.
Sampling from wells whose locations were determined without
adequate consideration of network design and geologic, hy-
draulic, and hydrochemical conditions may lead to significant
errors in data interpretation and conclusions. For example,
resolution of concentration distribution may be reduced in areas
where wells spacing intervals are too large for the scale of the
investigation.
To summarize the topic of monitoring well design, collection of
accurate ground-water quality data in three dimensions is
strongly dependent on the design of the ground-water monitor-
ing system, including both individual wells and well networks.
Significant errors can be introduced into sampling data, and the
resultant conclusions, if well intakes and filter packs are not
designed for ambient conditions, or are placed at inappropriate
depths or over excessive vertical intervals, or if borehole seals
are improperly installed. Furthermore, the design of monitoring
well networks may introduce error by inadequately representing
spatial variation through inadequate coverage of the site. Al-
though the magnitude of these errors is heavily dependent on
the geologic, hydraulic, and hydrochemical conditions present
at a particular site, order of magnitude effects are easily within
the realm of possibility.
DRILLING METHODS
Long-term or permanent disturbance of hydrogeologic and
hydrochemical conditions may result from the drilling method
used for monitoring well installation, possibly leading to signifi-
cant error during subsequent ground-water sampling. Drilling
methods may disturb sediments, allow vertical movement of
ground water and/or contaminants, introduce materials foreign
3
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to the subsurface, and clog void spaces. The extent to which
conditions are allered depends on the drilling method utilized
and the nature of the geologic materials (Gillham, et al.. 1983).
In addition, the properties of the contaminants at the site will
influence their sensitivity to the impacts of drilling.
Monitoring wells are commonly constructed by auger, rotary,
drill-through casing, and cable-tool methods. Auger drilling
methods utilize hollow- or solid-stem auger flights and are
generally restricted to use in unconsolidated materials. Rotary
techniques are classified based on the composition of the drilling
fluid (water, air, and various additives), the mode of circulation
(direct or reverse), and the type of bit (e.g. roller cone, drag, or
button) and are adaptable to most geologic conditions. The drill-
through casing method utilizes rotary or percussion drilling
techniques but uses a casing driver to advance temporary
casing in conjunction with the advancing borehole. In cable-tool
drilling, the borehole is advanced by alternately raising and
lowering a heavy string of drilling tools suspended from a cable.
Temporary casing can also be advanced as drilling progresses.
Some drilling methods may alterthehydrogeologic environment
by smearing cuttings (particularly fine sediments) vertically
along the borehole wall. This action may form a mudcake that
can reduce the hydraulic efficiency of the borehole wall and
modify ground-water flow into the completed well (Mcllvride and
Weiss, 1988). Smearing may also transport sediments between
zones and alter the vertical distribution of contaminants
adsorbed onto these sediments. In addition, methods that mix
sediments horizontally near the well bore may affect the trans-
port of contaminants near the completed well (Morin, et al.,
1988).
Vertical movement of ground water may occur during drilling,
primarily in situations where the borehole remains uncased
during drilling operations. Ground water can be transported
vertically by circulating drilling fluid or by hydraulic head differ-
ences between zones. In situations where contaminated
ground water is vertically stratified, vertical ground-water move-
ment may cause cross-contamination within the well-bore and
adjacent formation (Gillham et al., 1983). Movement of ground
water and contaminants between zones may also disrupt
hydrochemical equilibrium near the well.
Drilling activities can alter hydrochemistry as a result of contact
with introduced materials foreign to the subsurface environ-
ment. For example, lubricants or hydraulic fluids may enter the
borehole directly by falling from the drilling rig or may enter
indirectly via drilling fluids. In the latter case, contaminants may
originate in mud pumps, air compressors, or down-hole drilling
equipment. Soils or other material from the drilling site may also
enter the open borehole or may adhere to drilling equipment as
it is prepared for use. However, the material most commonly
introduced to boreholes is drilling fluid, which is used to remove
cuttings, stabilize the borehole wall, and provide cooling, lubri-
cation, and cleaning of the bit and drill pipe (Drisooll, 1986).
Drilling fluids commonly are composed of water or air alone or
in combination with clay (usually bentonite) and/or polymeric
additives.
Water from water-based drilling fluids that migrates away from
the borehole and mixes with ambient ground water may alter
hydrochemical conditions (Aller et al., 1989). For example,
introduction of a different water type may add contaminants or
disrupt hydrochemical equilibrium and cause precipitation of
dissolved constituents. During sampling, some of these precipi-
tates may be redissolved by ground water flowing toward the
well causing non-representative samples.
The bentonite additives used in many drilling fluids have a high
capacity for ion exchange and may alter hydrochemistry of
ground-water samples if not completely removed from the
borehole and surrounding formation (Gillham et al., 1983). Ion
exchange reactions that alter major ion composition may also
affect the concentrations of contaminants that form complexes
with these ions (Herzog et al„ 1991). Organic polymeric
additives can introduce organic carbon into ground water and
provide a substrate for microbial activity leading to errors in
water quality observations for long periods. Barcelona (1984)
reported that total organic carbon (TOC) levels in wells drilled
with fluids containing organic additives remained over three
times higher than background levelsfor two years. In that study,
TOC levels could not be reduced to less than two times back-
ground levels, even after substantial pumping.
The presence of drilling fluids in the formation surrounding well
installations, even after well development, was shown by Brobst
and Buszka (1986). That study, which used chemical oxygen
demand (COD) as an indicator of the presence of drilling fluid,
tested three additives of water-based drilling fluids: guar fluid,
guar fluid with a breakdown additive, and bentonite. Brobst and
Buszka (1986) reported that, using standard well purging and
sampling methods, COD levels were elevated for 50 days in a
well drilled with the guar-and-additive fluid, 140 days in a well
drilled with bentonite, and 320 days in a well drilled with the guar
fluid alone. More intense well purging reduced the COD levels,
but not to background values.
Contaminants present in drilling fluid may also mix with ground
water and bias sampling results. Mud pumps used with water-
based drilling fluids can add trace quantities of lubricants to the
fluid and deposit them in the wellbore and surrounding forma-
tion. Air compressors used to develop and maintain pressure of
air-based drilling fluids may have similar impacts. Filtration units
in air-based systems are designed to prevent this occurrence,
however, if feasible, the air stream should be sampled during
drilling to determine the effectiveness of the filter. Filtration is
generally not possible for water-based systems so if ground
water samples are to be collected for compounds related to
these lubricants it may be necessary to sample the drilling fluid
before it enters the borehole.
An outline of potential impacts of drilling methods on ground-
water sample quality is shown in Table 1, which was compiled
from the work of Scatf et ai. (1981), Gillham et al. (1983), Keely
and Boateng (1987), Aller et al. (1989), and Herzog et al. (1991).
WELL DEVELOPMENT
Ground-water monitoring wells are developed to restore the
sampling zone to conditions present prior to dnlling so that
sampled ground water can flow unimpeded and unaltered into
the well. Materials associated with thedrilling process, including
borehole wall mudcake, smeared and compacted sediments,
and drilling and other fluids, all must be removed from the
sampling zone to the extent possible. This can be accomplished
4
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TABLE 1. POTENTIAL IMPACTS OF DRILLING METHODS ON
GROUND-WATER SAVPLE QUALITY
Method Potential Impacts
Auger Drilling fluids generaly not used but water or
other materials added il heaving sands are
encountered may alter hydrochemistry
Smearing of fine sediments along borehole wall
Vertical movement of ground water and/or
contaminants wthin borehole
Lateral mixing of sediments near well bore
Rotary Drilling fluids are required and may cause cross-
contamination. vertical smearing of sediments,
alteration of hydrochemistry, and introduction of
contaminants
Smearing of fine sediments along borehole wall
Vertical movement of ground water and/or
contaminants wthin borehole
Drive-Through-Casing Drilling fluids required but advancing casing
reduces potential tor drilling fluid loss, cross-
contamination, and vertical smearing of
sediments, ground water, and contaminants.
Cable Tool Advancing casing reduces potential for cross-
contamination, and vertical smearing of
sediments, ground water, and contaminants.
in monitoring wells by several methods including surging with a
surge block mechanism, surging and pumping with compressed
air, pumping and overpumping with a pump, jetting with air or
water, backwashing with water, and bailing. Ail of these meth-
ods have the potential (to varying degrees) to influence the
quality of ground water samples; tha extent depends on the
nature of their action and the condition of the sampling zone after
drilling.
Development should be considered complete when representa-
tive samples can be collected and can continue to be collected
indefinitely. Unfortunately, under most ground-water sampling
circumstances determining when samples are representative of
in situ conditions is not possible, so some related criteria are
often chosen. Ideally, these criteria should include (1) the
production of clear water during development, and (2) the
removal of a volume of water at least equal to the amount lost to
the formation during drilling and well installation (Kraemer et al.,
1991). In addition, certain conditions may require that develop-
ment be continued after the well has been allowed to recover
from the first round of development efforts. This condition may
exist if the first round of samples exhibit turbidity
Incomplete or ineffective well development may allow drilling
and other introduced fluids to remain in the sampling zone or
may not remove all mudcake or smeared sediments from the
borehole wall. The presence of these materials may introduce
error by disrupting hydrochemical equilibrium or by introducing
contaminants to the well or sampling zone. In addition, these
materials can reduce the hydraulic conductivity of the filter pack
and formation and modify ground water flow near the well before
and during sampling.
Development methods that utilize air pressure can entrap air in
the filter pack and formation, disrupt hydrochemical equilibrium
through oxidation, or introduce contaminants from the air stream
to the formation and filter pack. These effects may be reduced
if precautions are taken to eliminate air contact with the well
intake. The addition of water during development may modify
hydrochemistry to an unknown extent or may introduce contami-
nants to the sampling zone, even if ail the water is removed
during development. In light of these potential problems, letting
methods that inject air or water directly above the well intake are
not recommended (Keely and Boateng, 1987). Likewise, other
methods that introduce air or water to the well (surging and
pumping with compressed air, and backwashing, for example)
also may not be suitable for monitoring well development (Aller
et al., 1989).
Development of wells at very high rates m ay displace filter pack
and formation materials and reduce the effectiveness of the filter
pack, particularly if the method involves excessive surging
(Keely and 8oateng, 1987). On the other hand, development at
low rates (as is generally attained with sampling pumps) may not
provide enough agitation to meet development objectives
(Kraemer et al., 1991). In many monitoring well situations, using
surge-block methods to loosen material and either pumping or
bailing to remove the material has been found to be an effective
development technique (Aller et al., 1989).
In low-yield wells, surging methods may result in excessive
mobilization of fine-grained materials. For example, in a study
conducted in fine-grained glacial tills, Paul et al. (1988) found
that auger-drilled wells developed by surge-block methods
produced samples with up to 100 times greater turbidity than
samples from similar wells developed by bailer. In addition, the
turbidity of samples from the surged wells did not significantly
decrease after a second round of sampling while samples from
the bailed wells showed a four-fold decrease (Paul et al., 1988).
Because these wells were drilled in low permeability sediments
without added fluids, the action of drawing down the water level
within the well by bailing may have been sufficient to provide
adequate development. On the other hand, bailing or pumping
techniques alone may not be effective in wells constructed by
drilling methods that introduce fluids or cause significant distur-
bance of sediments because the development force is dissi-
pated by the filter pack.
The potential impacts of monitoring well development on
ground-water sample quality are outlined in Table 2 which is
5
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TABLE 2. POTENTIAL IMPACTS Of DEVELOPMENT METHOOS ON
GROUND-WATER SAMPLE QUALITY
Method Potential Impacts
Surging with surge block Displacement of fitter pack and formation
materials or damage to the well intake (pnmarily
a problem in poorty designed and constructed
wells when surging is conducted improperly)
Excessive motorization ot fine-grained materials
from low-permeability formations
Entr^Jment of air in filter pack and formation
Disruption of hydrochemical equilibrium
Introduction of contaminants
Low-volume pumps may be incapable of
sufficient surging action (primarily in high-yield
wells with little or no drawdown)
Entrapment of air in filter pack and formation
Disruption of hydrochemical equilibrium
Introduction of contaminants
Excessive mobiization of fine-grained materials
from low-permeabiity formations
Backwashing with water Disruption of hydrochemical equilibrium
Introduction of contaminants
Baling May be incapable of sufficient development
action
based on the work of Ksely and Boateng (1987), Paul et al.
(1988), Alleretal. (1989), and Kraemeretal. (1991).
MATERIALS
Transfer of ground water from the subsurface sampling zona to
a sample container at ground surface often involves contact of
the sample with a variety of materials comprising the well,
sampling device, tubing, and container. Some of these materi-
als have the potential to bias chemical concentrations in
samples as a result of sorption, leaching, and chemical attack,
and biological activity (Barcelona et al., 1983). As a result, the
materials selected for ground-water sampling must be appropri-
ate for the hydrochemical conditions at the site and the constitu-
ents being sampled. Other factors that may influence the cho ice
of materials, including costs verses benefils, availability,
strength, and ease of handling, can be found in Aller et al.
(1989).
Materials commonly used in the ground-water sampling tram
can be divided into five general categories (modified from
Nielsen and Schalla, 1991):
1. fluoropolymers, which include polytetrafluoroethylene
(PTFE).tetrafluoroethylene (TFE), andfluorinated ethylene
propylene (FEP);
2. thermoplastics, which include polyvinyl chloride (PVC),
acrylonitrile butadiene styrene (ABS), polypropylene (PP)!
and polyethylene (PE);
3. metals, which include stainless steel (SS), carbon steel,
and galvanized steel;
4. silicones; and
5. fiberglass-reinforced, which include fiberglass-reinforced
epoxy (FRE) and fiberglass-reinforced plastic (FRP);
This document will focus on the most commonly used materials
including the rigid materials PTFE, PVC, and metals (particularly
SS) and the flexible materials PE, PP, PTFE, PVC, and silicone.
Chemical and Biological Impacts
Sorption, which includes the processes of adsorption and ab-
sorption, may remove chemical constituents from samples
thereby reducing the concentrations of these constituents from
levels present in the ambient ground water. If compounds
present in the ground water are removed entirely, false negative
analytical results will be produced. Additionally, desorption of
compounds previously sorbed can occur if water moving past
the material contains lower concentrations of the sorbant than
exists in the material. In this case, contaminants may be
detected in samples that do not exist in the ground water,
causing false positive analytical results. Sorption/desorption
processes may be particularly important in situations where
contaminant concentrations are at trace levels and change with
time or where samples contact potentially sorbing materials for
long periods (for example, during water level recovery in low-
yield wells or in inadequately purged wells).
Leaching of chemical constituents from some types of materials
may occur under the conditions present at many hazardous
waste sites. Constituents of the materials' matrix, or compounds
added during fabrication, storage, and shipment, may have
solubilities in water high enough to be leached under natural
ground-water conditions (Gillham et al., 1983). Ground water
contaminated by high concentrations of organic solvents may
cause significant degradation of the matrix of some polymeric
materials, resulting in leaching of various compounds
(Barcelona et al., 1983). As a result, false positive analytical
results can be produced if the source of target constituents in
ground-water samples is leaching from casing materials rather
than the ambient ground water. In addition, corrosion of metal
casing may introduce dissolved metals to ground-water
samples and reduce the integrity of the well.
Under certain ground-water conditions, well-casing materials
may impact biologic activity, and vice versa, in the vicinity of the
well (Barcelona et al., 1988b) and lead to errors that are difficult
to predict. For example, the presence of dissolved iron in
ground-water may favor the growth of iron bacteria near metallic
wells and degrade the casing and screen (Driscoll,1986). In
addition, permeation of contaminants or gases through materi-
Surging and pumping
with compressed air
Pumping and over-
pumping with pump
Jetting with air or water
6
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als may be a potential source of sample bias with flexible tubing
(Barker at al., 1987; Holm, 1988) but is unlikely with rigid
materials, as demonstrated by Berens (1985) for organic com-
pounds and rigid PVC pipe over time periods less than 100
years.
Rigid Materials
Rigid materials that contact ground-water samples are generally
used in well casings and screens, sampler components, and
filtration equipment.
PTFE
PTFE has been widely considered the best choice for monitoring
well materials because of its apparent resistance to chemical
attack and tow sorption and teaching potential. However,
several recent laboratory studies have shown that rigid PTFE
materials actually demonstrate a significant ability to sorb hydro-
carbons from solution. Sykes et al. (1986) found that PTFE
materials sorbed several hydrocarbons from a solution contain-
ing concentrations of approximately 100 ng/L, but did not report
quantities. Parker et al. (1990) found that rigid PTFE materials
sorbed significant quantities of all tested chlorinated organics
and a nitroaromatic; higher, in fact, than PVC materials. These
workers found that losses of some of these compounds from test
solutions (initial concentrations of each oompound were ap-
proximately 2 mg/L) exceeded 10% within eight hours. Like-
wise, rigid PTFE materials showed significant sorption of aro-
matic hydrocarbons in 24 hours of exposure for benzene, and
six hours for several other hydrocarbons (Gillham and
O'Hannesin, 1990). After eight weeks of PTFE exposure to
benzene, 75% losses from the test solution were observed.
In contrast, PTFE materials tend to show lower potential for
interaction with trace metals than PVC or SS (Barcelona and
Hettrich, 1986). For example, lead was the only metal of four
tested (arsenic, chromium, cadmium, and lead) in a laboratory
study to be actively sorbed onto PTFE materials although only
5% of the lead concentration in the test solution was removed
after 24 hours of exposure (Parker et al., 1990).
PVC
Earfy studies of PVC materials found substantial potential for
sample error from sorption and leaching effects. Many of the
conclusions about sorption were based on flexible PVC, which
has a much higher sorption potential than rigid PVC. Leaching
of high VOC concentrations was found to be a particular problem
from PVC solvents and cements used for casing joints and bailer
construction. Boettner et al. (1981) found cyclohexanone,
methylethylketone, and tetrahydrofuran leached into water at
concentrations ranging from 10 >ig/L to 10 mg/L for more than 14
days after the glue was applied to PVC pipe. In addition to these
compounds, methylisobuty(ketone was detected in ground-
water samples several months after the installation of cemented
PVC casing (Sosebee et al. (1982). The results of these studies
indicate that alternative methods of joining PVC casing, such as
threaded joints, should be utilized to reduce sample error.
Laboratory investigations show that threaded PVC well materi-
als sorb hydrocarbon compounds, but often at lower rates than
other polymers, including PTFE. Miller (1982) found little
absorption of six VOCs over a six-week period, with the excep-
tion of tetrachlorethylene which showed a 50% decline in
concentration in solution. These sorption results were signifi-
cantly lower than those from PE and PP casing materials.
Subsequent leaching from PVC was found to be at insignificant
levels for all six VOCs. Gillham and O'Hannesin (1990) found
that significant sorption ontc rigid PVC from a solution contain-
ing six hydrocarbons did not occur until 12 hours after exposure.
The PVC results were in contrast to three other rigid polymers
(PTFE, FEP, and polyvinylfloride) that showed significant up-
take of at least one of the six compounds within three hours of
exposure. After eight weeks of PVC exposure to benzene, 25%
losses were observed from the original solution concentration of
approximately 1.2 mg/L. Similar results were reported by Parker
et al. (1990) who found that PVC sorption of 10% of initial organic
compound concentrations didn't occur until over 72 hours of
exposure, while PTFE sorption ol 10% ol three of the 10 tested
organics occurred within eight hours of exposure. Two dichlo-
robenzene isomers showed the highest sorption rates on PVC:
signif icant losses were observed within eight hours. Sykes et al.
(1986) found no significant differences between PVC, PTFE,
and SS materials in their tendency to sorb six organics at
concentrations of approximately 100 ng/L each.
The results of these research studies indicate that rigid PVC
materials have relatively low potential for sorption and leaching
of organic compounds relative to other polymers when exposed
to dissolved concentrations generally found at hazardous waste
sites. However, Berens (1985) demonstrated that PVC may
soften and allow permeation of organic compounds if exposed
to nearly undiluted solvents or swelling agents for PVC. For this
reason, PVC well casing should be avoided under these
conditions.
PVC materials may also react with some trace metals. Miller
(1982) concluded that in a six-week exposure to test solution,
PVC materials did not affect chromium concentrations but that
lead concentrations declined over 75%. A subsequent experi-
ment showed that over 75% of the initial lead concentrations
were desorbed from the PVC material. Parker et al. (1990)
found that rigid PVC showed no measurable sorption or leaching
of arsenic or chromium but that cadmium was leached and lead
sorbed. For example, sorption of lead resulted in a 10% decline
in lead concentration in their test solution in four hours, while
subsequent desorption resulted in a 10% increase in lead
concentration after four hours.
Stainless Steel
SS casing materials are often used when conditions warrant a
strong, durable, corrosion-resistant material. Of the two types
available, Type 316 is somewhat less likely than type 304 to be
affected by pitting and corrosion caused by organic acids,
sulfuric acid, and sulfur-containing species (Barcelona et al.,
1983). However, long exposure to very corrosive conditions
may result in chromium and nickel contamination (Barcelona et
al., 1983), or iron, manganese, and chromium contamination
(U.S. EPA, 1987) of samples. Afield study by Barcelona and
Helfrich (1986) found that stagnant water samples from SS
installations showed higher levels of ferrous iron and lower
levels of dissolved sulfide than nearby PTFE and PVC wells,
suggesting leaching from the SS and precipitation of sulfide by
the excess iron. However, these workers demonstrated that
7
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proper well-purging techniques eliminated this stagnant water
from ground-water samples, providing representative ground-
water samples.
Laboratory experiments conducted by Parker et al. (1990)
examined the potential for sorption on type 304 and 316 SS
casing materials. These workers conducted experiments with
aqueous solutions of arsenic, cadmium, chromium, and lead at
concentrations of 50 ^g/L and 100 ^ig/L and found that after 10
hours, sorption on both type 304 and type 316 caused a 10%
decline in arsenic concentration in the test solution. Cadmium
concentrations increased 10% in five hours due to leaching from
type 304, before returning to initial concentrations after 72
hours. Cadmium leaching from type 316 caused a maximum
30% increase after 20 hours, with concentrations still 20%
above initial values after 72 hours. No measurable sorption of
chromium occurred for type 304, but 13% losses in 13 hours
were observed for type 316. Sorption of lead on type 304
materials led to 20% losses after only four hours of exposure,
and approximately 10% for type 316. Parker et al. (1990)
concluded from this work that determinations of the concentra-
tions of cadmium, chromium, and lead may be impacted by long-
term contact with stainless steel materials. Unfortunately, these
workers did not address whether well purging would eliminate
these impacts and provide representative ground-water
samples.
In a study with five halogenated hydrocarbons, Reynolds et al.
(1990) found type 316 SS caused losses of bromoform and
hexachloroethane over a five-week period. Losses of these
compounds from the test solution were insignificant until one
week, after which concentrations dropped up to 70% from initial
concentrations of 20 to 45 ng/L. The losses were attributed to
reactions involving the metal surfaces or metal ions released
from the surfaces and not to sorption (Reynolds et al.. 1990). A
study by Parker et al. (1990) with ten organic compounds at
concentrations of approximately 2 mg/L, found that type 304 and
type 316 SS casing resulted in no detectable sorption or leach-
ing effects after six weeks.
Other Metallic Materials
Steel materials other than stainless steel may be more resistant
to attack from organic solutions than polymers, but corrosion is
a significant problem, particularly in high dissolved-solids, acidic
environments (Barcelona et al., 1985a). Ferrous materials may
adsorb dissolved chemical constituents or leach ions or corro-
sion products such as oxides of iron and manganese (Barcelona
et al., 1988a). In addition, galvanized steel may contribute zinc
and cadmium species to ground-water samples. The weath-
ered steel surfaces, as well as the solid corrosion products
themselves, increase the surface area for sorption processes
and may therefore act as a source of bias for both organic and
inorganic constituents (Barcelona et al., 1985a; Barcelona et al.,
1983). Reynolds et al. (1990) determined that galvanized steel
showed a 99% reduction in concentrations of five halogenated
hydrocarbons in a five-week sampling period. Aluminum casing
caused concentration reductions of 90% for four of the com-
pounds. Although many of these aspects of steel materials have
not been quantified for typical ground-water environments, they
may be a significant source of sample error.
Alternate Materials
Although not as widely tested or used, FRE may represent a rigid
well material with relatively low potential for sample bias. In a 72-
hour laboratory study, none of the 129 priority pollutants were
detected to be leached from a powdered sample of the material
(Cowgill, 1988). A three-week dwell-time study of casing
materials by the same investigator resulted in detection of no
base/neutral or acid compounds. Gillham and O'Hannesm
(1990) concluded that sorption of benzene and other aromatic
hydrocarbons onto FRE was slightly greater than onto rigid PVC
but less than onto PTFE.
Borosilicate glass, another little-used well material, revealed no
sorption effects after a 34-day exposure to five halogenated
hydrocarbons (Reynolds et al., 1990). Of the ten well materials
tested in that study, only the borosilicate glass showed no
sorption characteristics. The low potential for sample error
indicated by that study suggests that further investigation of
borosilicate glass may be warranted to determine its suitability
for ground-water sampling.
Flexible Materials
Semi-rigid and flexible materials are used for transfer tubing and
other flexible components of the sampling/analysis train. In
general, these materials contain plasticizers for flexibility that
give them a higher potential than rigid materials to sorb or leach
compounds. Latex rubber tubing, flexible PVC, and low density
PE were all found to sorb greater quantities than more rigid
materials (Reynolds et al., 1990).
In a study of five tubing materials in solutions of four chlorinated
hydrocarbons, Barcelona et al. (1985b) found that most sorption
occurred in the first 20 minutes of exposure. With the exception
of tetrachloroethylene, the materials ranked in order of increas-
ing sorption PTFE, PP, PE, PVC, and silicone. PE showed the
highest sorption of tetrachloroethylene. Desorption from all
materials occurred rapidly with the same ranking: PTFE des-
orbed a maximum of 13% of the sorbed concentrations after one
hour while silicone desorbed 2%. From the results of this work,
Barcelona et al. (1985b) estimated sorptive tosses of chlori-
nated hydrocarbons from sampling tubing under typical flow
rates. As an example, using 15 m of 1/2-inch tubing, initial
concentrations of 400 ug/L for the four halocarbons, and a
sample delivery rate of 100 mL/min, these workers predicted 21,
29,48,67, and 74% sorptive losses for PTFE, PP, PE. PVC, and
silicone tubing, respectively.
Sorption tests conducted by Barker et al. (1987) found that
flexible PTFE led to 17% sorptive losses of benzene and 58%
losses of p-xylene after two weeks. For PE, 49% losses of
benzene and 91% losses of p-xylene were observed in two
weeks. As found in other studies, initial rapid tosses were
followed by gradual concentration declines in all compounds.
Desorption of these compounds followed a similar pattern,
approximately 40% of the initial benzene mass and 20% of the
initial p-xylene masses desorbed. Laboratory tests conducted
by Gillham and O'Hannesin (1990) showed PVC and PE tubing
caused sorptive losses of over 10% within five minutes of
exposure to six hydrocarbons in solution. After 24 hours, 90%
losses for the PVC and 80% losses for the PE had occurred.
8
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These studies suggest that flexible PTFE tubing has lower
potential for sorption and leaching than other materials, particu-
larly PVC and silicone. However, even PTFE tubing may have
significant impacts on concentrations of organic compounds in
ground-water samples, depending on duration of contact. It is
clear that the sorption and leaching affects of all materials used
as tubing or other flexible portions of the sampling/analysis train
should be considered when designing the sampling program.
Those materials that demonstrate high potential for sorption
and/or leaching should be avoided if those processes could
impact concentrations of the compounds of interest to the
investigation.
A further source of sample bias with respect to tubing is
transmission of compounds or gases through the tubing mate-
rials. In a study of PE and PTFE, Barker et al. (1987) detected
2 ng/L benzene and 15 |xg/L toluene passing through PE tubing
within three days and 15 ng/L and 100 ng/L. respectively, after
six days. Subsequent flushing of the tubing with three tubing
volumes of clean water reduced the concentrations of both
compounds detectable inside the tubing but they were still
detectable after twenty volumes were flushed. Under the same
conditions, the compounds did not pass through the PTFE
tubing in detectable concentrations. These workers suggest
that this mechanism may lead to sample bias in other polymeric
materials, although perhaps at rates somewhat less than those
exhibited by the flexible PE tubing, and could influence conclu-
sions about when well purging procedures or remediation activi-
ties are complete. Holm et al. (1988) studied the diffusion of
gases through FEP tubing, and found that the amount of gas
transferred is proportional to the tubing length and inversely
proportional to the f tow rate through the tube. Calculations by
the authors suggest that, given initially anoxic ground water,
oxygen diffusion through sampling tubing could lead to detec-
tion of DO and changes in iron speciation within tens of feet. The
results of these studies clearly indicate the potential errors that
transmission through flexible tubing might introduce when sam-
pling for both organic and inorganic compounds. This source of
error can be reduced by using appropriate tubing materials for
the sampling conditions and by minimizing tubing lengths.
Selection of Materials
It is clear from laboratory studies of casing materials that
concentrations of trace metals and hydrocarbons can be im-
pacted by sorption and leaching from PTFE, PVC, and metallic
casing materials. However, laboratory studies do not attempt to
duplicate the complicated, interrelated physical, chemical, and
biologic conditions present in the field that may cause materials
to behave very differently in the hydrogeologic environment, tt
is also important to keep in mind that most of these experiments
were conducted under static conditions and may not adequately
represent field conditions where stagnant water is generally
replaced with fresh ground water during well purging. In the
field, sorption of compounds onto casing materials between
sampling events may not affect subsequent ground-water
samples, as long as adequate purging andsampling procedures
are conducted. Desorption of previously sorbed compounds
after long-term exposure may be of somewhat greater impor-
tance because continuous desorption may impact trace-level
concentrations, which might have important implications to
remedial investigations where concentrations are expected to
eventually reach non-detectable levels. But again, proper
selection and implementation of materials and purging and
sampling methods will reduce the impact of these processes.
Given the above discussion and current state of research, some
generalizations may be made about the applicability of casing
materials to various ground-water contamination scenarios,
assuming that reducing sample error is the primary criterion for
selection. When monitoring for low hydrocarbon concentrations
in non-corrosive ground water, SS and PVC casing may be
appropriate choices. Because PTFE has been shown to intro-
duce error into hydrocarbon determinations, it may be most
applicable under conditions where SS and PVC are not. As
examples, SS would not be appropriate in corrosive ground
water or where determination of trace metal concentrations is of
primary concern and PVC wells would be inappropriate in
situations where solvents in moderate to high concentrations
could dissolve the PVC material. A summary of the properties
of rigid PVC, PTFE, and SS materials that may introduce sample
error is shown in Table 3.
Laboratory studies indicate that the potential for error from
flexible tubing is much greater than from rigid materials. For this
reason, efforts should be made to use tubing with low potential
for sorption and leaching and to minimize tubing length and time
of contact. It appears that sample error can be significantly
reduced by substituting flexible PTFE for PVC and silicone
where possible.
MONITORING WELL PURGING
Purging stagnant water from monitoring wells prior to sampling
is considered essential to collection of samples representative
of ambient ground water. Stagnant water may result from
biological, chemical and physical processes occurring between
sampling events. These processes may include biological
activity, sorption/desorption reactions with matenals of the well,
leaching from the materials of the well, degassing and volatiliza-
tion, atmospheric contamination, and foreign material entering
the well from ground surface.
An effective purging method must allow for flushing of the well
and sampling device of stagnant water without causing undesir-
able physical and chemical changes in the adjacent water-
bearing zone that may bias subsequent samples. Important
aspects of purging include purge volume, pumping rate, depth
of the purging device, and purging methods for low-yield wells.
Field experiments have shown that purging has important
impacts on sample chemistry, perhaps greater than other as-
pects of sampling protocol such as sampling device and mate-
rials (Barcelona and Helfrich, 1986).
Purge Volume
To ensure complete purging of a ground-water monitoring well,
there must be established criteria to determine when the water
in the well is representative of ambient ground water. Three
criteria commonly advocated to determine appropriate purge
volume have been described by Gibs and Imbrigiotta (1990) as:
(1) a specific, predetermined number of well-bore volumes, (2)
stabilization of the values of field chemical indicator parameters
(such as temperature, pH, and EC), and (3) hydraulic equilib-
rium between water stored in the casing and water entering the
casing.
9
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TABLE 3. PROPERTIES OF COMMONLY-USED WELL CASING
MATERIALS THAT MAY IMPACT GROUND-WATER SAMPLE QUALfTY
Material Properties
Polytetrafluoroethylene Moderate potential for sorption of hydrocarbons.
(PTFE)
Low potential for leaching of organic constituents.
Some potential for sorption and leacfting of
metals, but less than with thermoplastic and
metallic materials.
Particularly resistant to chemical attack, including
aggressive acids and organic solvents.
Not subject to corrosion.
Resistant to biological attack.
Stainless Steel (SS) Very low potential for sorption of hydrocartx>ns.
Not subject to leaching of organic constituents.
Significant potential for sorption and leaching of
metals.
Subject to chemical attack by organic acids and
sultur-containng species.
Subject to corrosion.
Subject to biological attack.
Polyvinytehloride (PVC) Potential for sorption of hydrocarbons, but may
be less than with ftuoropolymers.
Leaching of organic constituents may occur
through chemical degradation by .organic
solvents.
Sorption and leaching of some metals.
Subject to chemical attack by organic solvents.
Not subject to corrosion.
Resistant to biological attack.
The use of a specific number of well-bore volumes as the sole
criterion for purge volume has been applied extensively in
ground-water sampling with recommendations in regulations
and the literature ranging from less than one to over 20 (Herzog
et al., 1991). In addition, definitions of well-bore volume have
included the volume contained within the casing, that volume
plus the pore volume of the filter pack, and the volume of the
entire borehole. Despite its widespread use, the well-bore
volume approach does not directly address the issue of obtain-
ing representative ground water because there is no proven
relation between the number of well volumes removed and the
completion of purging. The combination of details of well
construction, contaminant distribution, and geologic and
hydrochemical conditions result in unique conditions at every
well such that the volume of water required for purging cannot
be determined a prion. It is impossible to predict the magnitude
of error that might be introduced by arbitrarily choosing a
number of well volumes that results in incomplete purging.
Determining purge volume by measuring field parameters is
also widely used. The assumptions implied in this approach are
that; (1) as these parameters stabilize, stagnant water in the well
has been replaced by ambient ground water, and (2) this water
contains representative concentrations of the compounds of
interest. However, field experiments conducted by Gibs and
Imbrigiotta (1990) showed that field parameters often stabilized
before the concentrations of VOCs. In almost 90% of their
experiments, field parameter measurements stabilized when
three well casing volumes had been purged while VOC concen-
trations stabilized after three well volumes in only about half of
the cases. Likewise, Pearsall and Eckhardt (1987)observed in
a series of field experiments that trichloroethylene concentra-
tions continued to change after three hours of pumping at 1.2 U
min while field parameters stabilized within 30 minutes. Further-
more, measurements of individual field parameters may not
reach stable values at the same purge volume suggesting that
some parameters are more sensitive to purging than others. For
example, Pionke and Urban (1987) found that temperature, pH,
and EC values of purge water from 14 wells studied generally
stabilized before dissolved oxygen and nitrate concentrations.
Puis et al. (1990) found that while temperature, pH, and EC
values generally stabilized in less than a single well-bore vol-
ume, other indicators such as dissolved oxygen and turbidity
required up to three well-bore volumes before stabilization. Puis
et al. (1990) considered reduction of turbidity to stable values
using low pumping rates as critical to the collection of represen-
tative metals samples. It should be pointed out that in all of the
cases mentioned above, reliance on commonly measured pa-
rameters (temperature, pH, and EC) alone would apparently
have underestimated the proper purge volume. These results
suggest that the choice of purge indicator parameters should be
made such that the indicators are sensitive to the purging
process and relate to the hydrochemical constituents of interest.
This can be accomplished by evaluating the patterns of indicator
parameters and ground-water constituents during well purging
(a purge-volume test) to determine the appropriate purge
volume.
Another implied assumption of the field parameter approach is
that purging will result in the stabilization of all constituent
concentrations at approximately the same purge volume. In
many hydrogeologic systems this assumption may not be valid.
For example, in aquifers contaminated by several VOCs, con-
centration trends during pumping may be very different. In an
evaluation of a purge-volume test, Smith et al. (1988) found that
concentrations of two compounds started relatively high and
decreased with purging to below detectable levels. Two other
compounds that were undetected at three casing volumes were
detected at four casing volumes and their concentrations in-
creased until stabilizing at ten casing volumes. Afifth compound
remained at a constant concentration throughout the purge-
volume test. The authors did not report the concentrations
observed or the volumes pumped, but it is dear that under these
10
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conditions the choice ol purging volume could significantly
impact interpretations of contaminant concentrations.
It is important to keep in mind that the distribution ol contami-
nants in limited plumes within a ground-water system is gener-
ally in oontrast to the more homogeneous distribution of natural
hydrochemical conditions in space and time. Consequently,
attaining stable concentrations of field parameters, or even
gross chemistry, may not indicate a representative sample of the
targeted aquifer volume around a monitoring well (Keely and
Boateng, 1987). As a result, these workers suggest that the
'inherent variability of the concentration of contaminants in
many plumes far outstrip the additional variability potentially
induced by incomplete purging,' and recommend that spatial
and temporal variations in contaminant concentrations be stud-
ied to determine optimum purge volumes.
Methods of determining purge volume by estimating when
hydraulic equilibrium occurs between water stored in the casing
and water entering the casing may be useful where conserva-
tive, non-varying constituents are being monitored. However,
determining hydraulic equilibrium by estimating the time at
which water levels in the well are no longer affected by casing
storage (the method of Papadopulos and Cooper, 1967) may
lead to erroneous results (Gibs and Imbrigiotta, 1990). These
workers compared the calculated hydraulic equilibrium volume
to measurements of field parameters and VOC concentrations
during several well purging experiments and found that the
calculated volume consistently underestimated the volumes
required to reach both stable field measurements and stable
VOC concentrations. The casing storage method might provide
an approximation of purge volume under conditions where
conservative, non-varying constituents are being monitored but
the available evidence suggests that only sampling for the
constituents of interest will provide a direct indication of when
their concentrations stabilize.
Recent research reviewed by Puis et al. (1990) demonstrates
that contaminants may be transported in ground water by
association with colloidal-sized partides which are generally
described as particles less than 10 in diameter. Where
contaminant transport by association with colloids is an impor-
tant mechanism, obtaining representative concentrations of
mobile colloids becomes critical to sample representativeness.
However, the acts of purging, sampling, and even placing the
sampling device in the well have been demonstrated to signifi-
cantly impact colloidal suspension in the sampling zones of
monitoring wells (Puis et al., 1991; Kearle et al., 1992). If a
significant portion of contaminants are transported in associa-
tion with colloids, the results of these investigations and others
suggest minimizing or eliminating purging, minimizing sampling
flow rates (100 to 500 mL/min), and using dedicated sampling
devices placed within the well intake may all be necessary to
collect representative ground water samples. This low-volume
approach to purging and sampling was earlier proposed by
Robin and Gillham (1987) when sampling for conservative, non-
varying parameters in high-yield wells. Using non-reactive
tracers, these workers demonstrated that natural ground water
movement through the well intake was sufficient to prevent the
formation of stagnant water with respect to conservative, non-
varying parameters, making purging large volumes unneces-
sary. Robin and Gillham (1987) pointed out that, under these
hydraulic and hydrochemical conditions, representative
samples can be collected with little or no purging using dedi-
cated devices positioned within the well intake In order to
resolve the issue of low-volume purging, however, it appears
that more research is necessary to better understand colloid
movement in ground-water environments, their importance to
contaminant transport, and their implications to purging and
sampling techniques.
Purge Rate and Depth
It was suggested previously that the pumping rate at which
purging is conducted may impact sampling results. Although
few detailed studies have been conducted to directly address
this issue, the results of a few specific field studies suggest the
types of impacts that purging rates might have on sampling
results. For example, Imbrigiotta et al. (1988) reported that
purging rates of 40 Umin were found to produce VOC concen-
trations up to 40% higher than concentrations obtained at
purging rates of 1 LYnin. Likewise, purging with a high-speed
submersible pump at a rate of 30 Umin was found to generally
produce higher colloid concentrations and larger particle sizes
than a low-speed pump at rates lower than 4 Umin (Puis et al.,
1990). Despite these colloid differences, however, metals and
cation concentrations did not necessarily correlate to pumping
rate. Both investigators attributed the variability to the effects
that different pumping rates had on the distribution of
hydrochemical conditions near the well. Imbrigiotta et al. (1988)
further concluded that the variability in VOC concentrations
caused by purging rate was of the same magnitude as that
observed in a comparison of seven types of sampling devices,
suggesting that purging rate may be at least as important to the
collection of representative samples as the type of device
utilized. Puis et al. (1990) suggested that the colloid differences
might also have resulted from entrainment of normally non-
mobile suspended particulates in the wells.
Although the issue remains unresolved, it appears that employ-
ing pumping rates that allow sample collection with minimal
disturbance of the sample and the hydrochemical environment
in and near the well may aid in minimizing sampling error. To this
end, it has been suggested that the purging rate be chosen such
that the rate of ground water entering the well intake is not
significantly higher than the ambient ground-water flow rate
(Puis and Barcelona, 1989). Under typical hydraulic conditions,
this may be possible with pumping rates between 100 and 500
mL/min.
The depth at which purging is conducted may also affect sample
representativeness. At high pumping rates or in low- and
medium-yield wells, purging at depths far below the air-water
interface may introduce error because stagnant water from the
well above the pump may be drawn into the pump inlet. Under
these conditions, pumping near the air-water interface signifi-
cantly reduces the time required to remove stagnant water by
reducing mixing from above the pump intake (Unwin and
Huis,19B3; Robin and Gillham, 1987). Keely and Boateng
(1987) suggest lowering the pump during purging so as to
further reduce the possibility of migration of stagnant water into
the intake during sample collection. On the other hand, under
high-yield conditions, placing the pump at the well intake and
utilizing low pumping rales may serve to isolate the stagnant
water in the well bore above the pump thereby providing
representative samples with minimal purging (Barcelona et al.,
11
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1985, Robin and Gillham, 1987). Unwin and Maltby (1988)
reported that pumping at virtually any depth within a well,
including the intake, may lead to contamination of samples by
stagnant water from above the pump inlet although their labora-
tory investigation demonstrated that at a pumping rate of 1 L/
min, samples collected within the well intake contained less
stagnant water than samples collected above the well intake.
Regardless of the depth of the pumping device, if a stagnant
water zone develops near the water surface subsequent move-
ment of the pump or placement of a sampling device through this
zone may cause contamination of the device by stagnant water.
As suggested above in the discussion of purge volume, certain
hydrogeologic conditions and chemical constituents may re-
quire that samples be collected with little or no purging using
dedicated devices positioned within the well intake. Underthese
circumstances, it would also be necessary to utilize low purging
and sampling rates so as to minimize disturbance of the sample
and sampling environment and to prevent migration of stagnant
water from the well bore down into the sampler intake.
Purging In Low-Yield Wells
Purging low-yield wells introduces conditions that by definition
donl occur in medium- to high-yield wells. These conditions,
which tend to have their greatest impact on constituents that are
sensitive to pressure changes and/or exposure to construction
materials or the atmosphere, often result from dewatering the
filter pack and well intake. Dewatering may produce a large
hydraulic gradient between the adjacent water-bearing zone
and the filter pack as a result of the large drawdown in the well
and the low hydraulic conductivity of the formation. One
consequence of this condition may be the formation of a seep-
age face at the borehole wall causing ground water entering the
borehole to flow down the borehole wall and fill the dewatered
filter pack from the bottom up. Formation of a seepage face
increases the surface area oi the interlace between the liquid
phase (ground water) and vapor phase (headspace in the well)
available for transfer of solutes. Another consequence of the
large hydraulic gradient is the sudden pressure decline from the
pressure head in the water-bearing zone to atmospheric pres-
sure in the pumped well. The sudden release of this pressure
may cause losses from solution (by degassing or volatilization)
of solutes that have combined partial pressures, with that of
water, greater than atmospheric. Finally .because water levels
recover slowly in low-yield wells, significant changes in the
chemical composition of the ground water may occur through
sorption, leaching, or volatilization before sufficient volume is
available for sample collection.
In a field study of purging and sampling in low-yield wells,
Herzog et al. (1988) found that some VOC concentrations
increased significantly from pre-purging conditions during the
first two hours of water level recovery. For example, chloroben-
zene concentrations increased from 25 ng/l before purging to
over 125 ng/L at two hours after purging. Concentrations
generally did not change significantly after two hours, although
some concentrations declined. Although Herzog (1988) pro-
vided no explanation for the observed concentration trends,
they were likely caused by more representative ground water
entering the well and replacing the purged stagnant water.
Smith et al. (1988) reported very different results in their field
study of a trichloroethylene plume. Concentrations of trichloro-
ethylene declined from 100 ng/L directly after purging to 10 ^g/
L 24 hours after purging. In a laboratory study, McAlary ana
Barker (1987) found that if the water level in a simulated well was
drawn down below the intake, VOC concentrations during
recovery declined 10% in five minutes and 70% in one hour
These changes were attributed to volatilization from the water as
it entered and filled the well.
In summary, aspects of well purging important to collection of
representative samples include purging volume, pumping rate,
depth of the purging device, and time of sampling in low-yield
wells. Although error is strictly dependent on individual well and
site conditions, the available evidence suggests that order-of-
magnitude errors may easily result from improper purging
techniques. In low-yield wells, time of sampling is clearly an
important source of error although there are too few data
available to completely understand concentration trends in
these situations.
Contamination concentrations during purging vary in ways that
are often difficult to predict, and various compounds may even
exhibit opposite trends. To estimate the appropriate purge
volume, it may be necessary to conduct preliminary purge-
volume tests with sampling at regular intervals during purging.
These tests may be useful for determining how indicator param-
eters and constituent concentrations respond to purging rates,
purging volumes, and the distribution of contaminants around
the well. In addition, for certain sensitive constituents such as
trace metals under certain hydrogeologic and hydrochemical
conditions, low-volume purging and sampling should be consid-
ered with dedicated sampling devices installed atthe well intake.
SAMPLE COLLECTION
Sample collection involves physical removal and transport of
ground water from depth (generally from a monitoring well) to
ground surface and into a sample container. As such, collection
methods may have great potential for alteration of the sample's
chemical state. Sampling devices must be chosen and used
carefully to ensure that error is minimized. Important aspects of
sample collection include sampling device, collection time after
purging, and sampling depth.
Chemical Impacts
Sampling devices can cause chemical changes in the sample by
contact with materials of the device (sorption, desorption. or
leaching) or by the physical action of the device. Although the
materials of the device are a potentially significant source of
sample error, that topic was discussed previously and the
following discussion will address chemical changes produced
only by the operation of the sampling device.
Because fluid pressure in the saturated zone is greater than
atmospheric, ground-water samples brought to the surface will
tend to be under higher pressure conditions than the ambient
atmosphere. Exposure of these samples to the lower atmo-
spheric pressure will cause degassing and/or loss of volatile
constituents until the partial pressures of the contained volatile
components reaches equilibrium with atmospheric pressure.
Degassing may cause losses of oxygen (02), methane (CH ),
nitrogen (Nj), or carbon dioxide (CO;). while volatilization might
affect any solute that exists as a liquid, solid, or gas under in situ
12
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ground-water temperature and pressure conditions (Gillham et
al., 1983). Furthermore, loss of COz may raise the pH which can
lead to precipitation of dissolved constituents, particularly iron
(Gibbet al., 1981). Constrictions in the flow path within a device
may also raise the sample pH by changing the partial pressure
of C02 (Herzog et al., 1991).
Exposure of samples to the atmosphere, or the driving gas used
in some devices, may introduce oxygen causing oxidation of
iron, manganese, cadmium, or other species. Oxidation of
ferrous iron to feme iron has important implications to the
speciation and concentrations of many constituents in ground
water samples (Herzog etal., 1991). Contaminants may also be
added to the sample by exposing it to the atmosphere or driving
gas.
Sampling Devices
Sampling devices designed for use in conventional monitoring
wells can be divided into four general types: grab, positive
displacement (no gas contact), suction lift, and gas contact
(Pohlmann and Hess, 1988). Grab samplers include open
bailers, point-source bailers, and syringe samplers. Positive
displacement samplers are usually submersible pumps such as
bladder pumps, gear-drive pumps, helical-rotor pumps, and
piston pumps. Suction lift devices include peristaltic pumps and
surface centrifugal pumps while gas contact pumps include
those devices that lift water to the surface by direct gas pressure.
Submersible centrifugal pumps, which operate on the principle
of positive displacement at low flow rates, develop a partial
vacuum at the pump impellers at higher flow rates. For this
reason, high-speed submersible centrifugal pumps without vari-
able motor speed capability should be considered as distinct
from positive displacement pumps. On the other hand, sub-
mersible centrifugal pumps are now available that can be used
in 5.1-cm (2-inch) diameter wells and that allow adjustment of
the motor speed to produce very low flow rates. If used at low
flow rates, these low-speed pumps could conceivably eliminate
the application of a partial vacuum to the sample and thereby
can be considered as positive displacement pumps. Discussion
of the operating principles of many of ground-water sampling
devices, and their potential for sample bias, can be found in
Gillham et al. (1983).
Sampling devices for conventional monitoring wells can be used
either portably or in a dedicated mode. Portable devices are
used to collect samples in more than one well and so may cause
cross-contamination between installations or sampling events if
not properly decontaminated. Dedicated devices are perma-
nently installed in a single well and are generally not removed for
cleaning between sampling events. Dedicated samplers, when
also used for well purging, may not have adequate flow control
for effective purging in large wells (high discharge rate) and
sampling (low discharge rate). Furthermore, parts of dedicated
samplers may sorb contaminants during periods of contact with
ground water between sampling events and then release them
during sample collection. Alternatively, if inappropriate materi-
als are used in the construction of dedicated samplers, contami-
nants may leach from these materials between sampling
events.
To study the effects of sampling devices on sample quality,
investigations have been conducted both in the laboratory and
in the field. Laboratory studies can provide values of absolute
sample error by testing under controlled conditions, particularly
constituent concentration. However, by their very nature, labo-
ratory experiments represent ideal conditions that can never be
duplicated in the field and therefore may not include important
field-related errors. On the other hand, field studies include ail
the physical, chemical, biological, and operating conditions
present in field sampling efforts, but the true concentration of the
constituents of interest are unknown. As a result, field compari-
son studies cannot provide values of absolute sample error, only
the relative ability of individual devices to recoverthe constituent
of interest.
Values of field chemical indicator parameters can often be the
first indication of sample errors due to sampling device. Labo-
ratory investigations of a wide range of sampling devices by
Barcelonaet al. (1984) revealed that pH and redox potential (Eh)
were the most sensitive to sampling device. The largest errors
were produced by a peristaltic pump (an increase of 0.05 pH
units and a 20 mV decline in Eh). All tested devices had 02 and
CH^ losses of 1% to 24%, although positive displacement
devices and an open-top bailer resulted in the lowest losses and
the highest precision in that study. A field study by Schuller et
al. (1981) found that, as a result of CO, stripping, an air-lift pump
and a nitrogen-lift pump produced pH values up to 1.0 pH unit
higher than a peristaltic pump and opentop bailer. Other field
studies concluded that open-top and dual-valve bailers pro-
duced no more error in field parameter values than bladder
pumps (Houghton and Berger, 1984). In that study, which used
bladder pump values as a standard for comparison, a peristaltic
pump and a high-speed submersible centrifugal pump had
increases in pH of about 0.06 pH units and approximately 20%
declines in dissolved oxygen (DO) concentrations. A gas-driven
piston pump had an increase in DO of 8% to 36%. Temperatures
increased up to 5% in samples collected with the peristaltic and
piston pumps and 14% in samples collected with the high-speed
submersible centrifugal pump.
Most major dissolved ions are relatively stable and not greatly
affected by collection method. Schuller etal. (1981) determined
that concentrations of calcium, chloride, fluoride, potassium,
magnesium, and sodium collected at two field sites were not
significantly affected by the choice of suction, gas-contact, or
bailer device. Dissolved metals, on the other hand, are very
sensitive to sample aeration and degassing during sampling.
Schuller et al. (1981) found that iron and 2inc concentrations in
samples collected with two gas contact devices were, at most,
30% of those collected with either a peristaltic pump or a bailer.
Field studies of 18 wells with seven sampling devices by
Houghton and Berger (1984) showed significant declines in
metals concentrations for a gas contact devee when compared
to positive displacement pumps, grab samplers, and a peristaltic
pump. Houghton and Berger (1984) also found that
coprecipitation of arsenic and zinc with iron led to significant
losses of these constituents in samples collected with a high-
speed submersible centrifugal pump.
Sampling device impact on VOC concentrations is of particular
importance because of the high sensitivity of these compounds
to sample aeration and degassing and the critical need for
accurate VOC data in many site investigations. Several labora-
tory experiments have shown that positive displacement de-
vices (bladder, piston, and helical-rotor pumps) and conven-
13
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tional grab samplers (open-top and dual-valve bailers) provide
the most accurate VOC concentrations (Barcelona at al. 1984;
Unwin, 1984; Schalla et al., 1988; Unwin and Maltby, 1988).
Although the bladder pump and bailers that Barcelona et al.
(1984) tested produced less than 3% losses in VOC concentra-
tions, these same devices produced up to 10% losses in other
studios, ever, under carefully -controlled conditions. Suction and
gas-contact devices tested in these studies, and a study of
peristaltic pumps by Ho (1983), resulted in 4% to 30% losses in
VOC concentrations. Of those devices that performed well, no
relation was found between sampler accuracy and VOC con-
centration over a range of 80 to 8000 (ig/L (Barcelona et al.,
1984; Unwin, 1984). The devices that performed poorly, how-
ever, often revealed significant increases in error as concentra-
tion increased (Barcelona et al., 1984). From these laboratory
studies it appears that certain classes of samplers, specifically
suction and gas-contact, can lead to significant error in VOC
concentrations as a result of volatilization from the sample
during collection.
A positive relation between increased losses of VOCs from
solution with increase in Henry's law constant was predicted by
Pankow (1986) based on theoretical considerations of the
factors leading to bubble formation in water during sampling.
Physical experiments have shown a strong positive correlation
between compound volatility and Henry's law constant for a
peristaltic pump, some correlation for a helical-rotor pump, but
no correlation for a bailer and bladder pump (Unwin and Maltby,
1988). On the other hand, Barker et al. (1987) found no clear
correlation for a peristaltic pump and gas-drive sampler and
Barker and Dickhout (1988) found no clear correlation for a
peristaltic, bladder, or inertial-lift pump, although the range of
Henry's law constants was small. These findings suggest that
compound volatility may not be an important source of bias for
some positive displacement and grab samplers but there may
be potential for losses for samplers that impose a suction on the
sample.
Many field comparisons of sampler effectiveness verify the
findings of laboratory experiments, despite the increased num-
ber of variables involved in the field studies. Investigations
involving a variety of field conditions by Muska et al. (1986),
Pearsall and Eckhardt (1987), Imbrigiotta et al. (1988), Liikala et
al. (1988), Yeskis et al. (1988), and Pohlmann et al. (1990)
concluded that positive displacement devices produced the
highest VOC concentrations, and therefore introduced the least
error into VOC determinations. The accuracy of grab samplers
was more variable: some studies showed little difference
between the VOC recoveries of bailers and positive displace-
ment pumps (Muska et al. (1986); Imbrigiotta et al. (1988);
Liikala et al. (1988)), but Imbrigiotta et al. (1987), Yeskis et al.
(1988), and Pohlmann et al. (1990) reported that bailer VOC
concentrations were significantly lower than positive displace-
ment pumps; 46% to 84% lower in the work of Yeskis et al.
(1988). Pearsall and Eckhardt (1987) found that a bailer was as
accurate as a positive displacement pump at concentrations in
the range of 76 to 79 |ig/L but recovered 12% to 15% lower
concentrations in the range 23 to 29 ng/L.
Another grab sampler, the syringe sampler, also produced
mixed results. Muska et al. (1986) concluded that syringe
sampler accuracy and precision were not significantly different
from those of the positive displacement pumps while Imbrigiotta
et al. (1988) concluded that syringe sampler accuracy was lower
than the pumps but that precision was comparable. Other
samplers field-tested produced significant error: a peristaltic
pump and surface centrifugal pump were found by Pearsall and
Eckhardt (1987) to be less accurate, but not necessarily less
precise than the other samplers tested. Imbrigiotta et al. (1988)
found the same for a peristaltic pump.
In ground-water environments charged with dissolved gases,
collection of accurate VOC samples can be even more problem-
atic. VOC losses of 9% to 33% were produced by a peristaltic
pump in laboratory and field studies of water containing high C02
(laboratory study) and CH4 (field study) concentrations (Barker
and Dickhout, 1988). Losses of 13% to 20% were produced by
a bladder pump in the laboratory study, while an inertial-lift pump
produced no losses. No differences between results from these
two pumps were observed in the field. The CO concentrations
used in the laboratory investigation were higner than under
environmental conditions, but this study nonetheless suggests
that degassing during sample collection, even with a positive
displacement pump, can lead to significant error in VOC concen-
trations (Barker and Dickhout, 1988).
Several "in situ* devices have been developed to alleviate some
of the problems inherent to conventional monitoring wells and
sampling devices. These devices generally utilize sample
containers under reduced pressure to collect samples directly
from the water-bearing zone, without exposure to the atmo-
sphere or excessive agitation. In a field study, Pohlmann et al.
(1990) found that two types of in situ devices delivered samples
with VOC concentrations that were not significantly different
from those collected by a bladder pump in a conventional
monitoring well.
Although the field studies outlined above cannot provide values
of absolute sample error, they do provide information on the
effectiveness of various devices under actual operating condi-
tions. The results of the laboratory studies, in conjunction with
field studies, indicate that suction pumps are very likely to
introduce significant error into VOC determinations.
Grabsamplers, especially bailers, are also likely to produce
errors if not operated with great care because their successful
operation is closely related to operator skill. Under certain
conditions, for certain parameters, and if operated by skilled
personnel, bailers can produce representative samples. How-
ever, much of the research outlined here indicates that positive
displacement pumps consistently provide the lowest potential
for sample error. Appropriate application of most types of
positive displacement pumps can reduce sampling device con-
tribution to error well below the levels of some other aspects of
ground-water sampling protocol.
A summary of the impacts that some commonly-used sampling
devices have on ground-water sample quality is shown in
Table 4 which was compiled from the sources referenced in this
section and Nielsen and Yeates (1985).
Collection Depth and Time after Purging
The length of time between well purging and sample collection
may influence the representativeness of samples by exposing
ground water to the effects of atmospheric diffusion, interaction
with well materials, and contaminant volatilization. Smith et al.
14
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TABLE 4. SOME IMPACTS THAT THE OPERATING PRINCIPLES OF
GROUND-WATER SAMPLING DEVICES MAY HAVE ON GROUND-
WATER SAMPLE QUALITY (WITH THE EXCEPTION OF GRAB
SAMPLERS, rT IS ASSUMED THAT THESE DEVICES REMAIN IN THE
WELL DURING THE SAMPLING PROCESS).
Operating Principle Impacts
Gas Contact Contact with drive gas may cause loss of
dissolved gases and increase pH.
Contact with drive gas may volatilize sensitive
solutes.
Exposure to driving gas may introduce
contaminants or oxidize sensitive constituents.
Grab Contact with atmosphere during sample recovery
and transfer may cause loss of dissolved gases
and increase pH.
Contact with atmosphere during sample recovery
and transfer may volatilize sensitive solutes.
Exposure to atmosphere during sample recovery
and transfer may introduce contaminants or
oxidize sensitive constituents.
May be contaminated when passing through
zone of stagnant water.
Positive Displacement Minimal if discharge rale is low.
Suction Lifl Application of suction to sample may cause loss
of dissolved gases and increase pH.
Application of suction to sample may volatiize
sensdive solutes.
High-Speed Suction applied at pump intake may cause loss
Submersfcie Centrifugal of dissolved gases and increase pH.
Suction apptad ai pump intake may cause
volatilization of sensitive solutes.
until sufficient volume is available. Determination of sample
collection time in low-yield wells is more problematic and may
require site-specific sampling experiments.
To reduce potential errors caused by mixing with stagnant well
water during sampling, research has suggested that the sam-
pler intake be located either within the screened interval
(Giddings, 1983; Bryden et al„ 1986; Robin and Gillham, 1987)
or at the top of the screened interval (Unwin, 1982; Barcelona
and Hetfrich, 1986) so samples can be obtained soon after fresh
ground water enters the well bore. However, in cases where
wells are screened over a long interval, it is important to
determine if contaminants are vertically stratified in the well.
Pearsall and Eckhardt (1987) found that TCE concentrations of
samples collected at the top of a 10-foot screened interval were
30% lower than those collected at the bottom and attributed the
difference to vertical stratification of VOCs within the screened
interval. Errors associated with sampler intake placement have
not been quantified to date but are likely strongly controlled by
conditions at each well.
The use of samplers that must pass through the zone of stagnant
water that invariably remains near the water level, even in a
properly-purged well, may also introduce error. For example,
grab samplers, which often require repeated entry and retrieval
from the well during sampling, may be contaminated by this
zone of stagnant water or may mix stagnant water into the water
column. Likewise, if the purging device is not used for sampling,
removal of the purging device and installation of the sampling
device may have a similar effect. The use of a dedicated device
for both purging and sampling would significantly reduce this
source of error but may introduce others.
SAMPLE FILTRATION
Ground-water samples collected for analysis of certain constitu-
ents are often filtered in the field prior to transfer to the appropri-
ate container. Reasons for filtration include prevention of
geochemical reactions that might occur with particulates during
sample shipment and storage, removal of suspended sedi-
ments so as to analyze only dissolved constituents, and removal
of fine-grained sediments which might interfere with laboratory
analyses. Because filtration may contribute to sample error by
the method employed or by the choice to filter, it is of the utmost
importance to confirm the objectives of the sampling program
and the implications of filtering when choosing whether to filter
and, if so, the filtration technique.
w to san1^0 Puis and Barcelona (1989) point out that if mobile trace metal
cause degassing or vouwzatnn. species are of interest to the investigation filtration may remove
L j. metals adsorbed onto some colloidal partides, leading to under-
hwai produced by pump motor may increase estimates of dissolved metals concentrations and, therefore,
sample temperature. concentrations of mobile species. Conversely, if the objective of
—————1—imetals analysis is to quantify total dissolved metals concentra-
tions, colloids with sorbed metals that pass through the filter
material may result in overestimates of dissolved metals con-
(1988) found that trichloroethane concentrations in a well de- centrations (Puis and Barcelona. 1989). These workers indicate
clined from 170 ng/L immediately'after purging to 10 ng/L 24 that filtration should not be used as a means of removing from
hours later. To ensure consistency and to reduce potential the sample particulates that result from poor well construction,
errors when sampling in high-yield wells, it is generally recom- purging, or sampling procedures because the misapplication of
mended that samples be collected immediately following filtration may introduce substantial bias to trace metal determi-
completion of well bore purging. In low-yield wells, however, low nations. If filtration is deemed necessary, it should be conducted
water level recovery rates may require that sampling be delayed soon after sample collection as temperature changes, COj
15
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invasion, or the presence of particulates may have adverse
effects on trace metal concentrations or dissolved solids content
(Unwin, 1982). Factors important to proper field filtration include
filter pore size, material, and method, and holding time prior to
filtration.
Filter pore size has very important implications for determina-
tions of metal species and major ions in ground-water samples
as a result of the inclusion of undissolved material. Constituents
showing the greatest sensitivity to filter pore size include iron
and zinc (Gibb at al„ 1981), iron and aluminum (Wagemann and
Brunskill, 1975), and iron, aluminum, manganese, and titanium
(Kennedy et al.. 1974). In all cases, larger filter pore sizes
produced higher concentrations of these constituents because
the larger pore-size filters allowed more particulates to pass. In
fact, Kennedy et al. (1974) found that concentrations of some
metal species in samples filtered through 0.45 urn filters were up
to five times higher than in samples filtered through 0.10 nm
filters. These results suggest that if field-filtering is deemed
necessary, smaller pore size filters may reduce sample error.
Sorptive losses of trace metals during filtration can also intro-
duce error into metals determinations. Truitt and Weber (1979)
found that both cellulose acetate and polycarbonate 0.4 urn filler
membranes sorbed copper and lead from solution. For ex-
ample, losses of copper averaged 8.6% with cellulose acetate
membranes and 1.1% with polycarbonate membranes.
Gardner and Hunt (1981) found that sorption of lead onto
cellulose acetate membranes resulted in losses of 20 to 44%
from a synthetic solution. These losses were reduced to 5 to
24% by pre-rinsing the filter apparatus with the test solution
(Gardner and Hunt, 1981). Studies by Jay (1985) found that
virtually all filters require pre-rinsing to avoid sample contamina-
tion by leaching of anions from the filter material.
Although filter material and pore size have been the subject of
considerable research, less effort has been directed toward
understanding the effects of filtration method on dissolved
constituents. Of the few studies available, Stolzenburg and
Nichols (1985) investigated the effects of sampling and filtration
method on concentrations of iron and arsenic. Their laboratory
study showed that samples that were vacuum-filtered after a 10-
minute holding time delay experienced iron losses of 20% to
90% and arsenic losses of 45% to 100% compared to in-line
filtered samples. The ranges of percentages were due to the use
of several types of sampling devices. Later experiments by
Stolzenburg and Nichols (1986) added immediate vacuum
filtering of samples. Both immediate and delayed vacuum-
filtration produced similar iron concentrations but these concen-
trations were 17% to 67% lower than concentrations produced
by in-line filtration. In both the 1985 and 1986 reports, in-line
filtering produced concentrations that were comparable to the
source concentrations of approximately 8 mg/L iron and 0.05
mg/L arsenic suggesting that in-line filtration methods were the
most effective of those tested. These experiments also sug-
gested that filtration method may cause greater losses of certain
constituents than the type of sampling device used. Unfortu-
nately, commonly-used pressure filtration methods were not
compared to in-line and vacuum filtration methods in these
experiments.
Clearfy, sample filtration can lead to substantial error in trace
metal determinations even if procedures are carefully followed.
Because of this great potential for error, filtration should not be
used to correct for sedimentation problems that result from
poorly designed or constructed wells or incomplete develop-
ment. If filtralion is deemed necessary, pre-cleanmg the filters
can reduce error. In addition, the limited research into filtration
methods in ground-water investigations suggests that in-line
methods may result in the least sample error. However, even
under ideal conditions, sample filtration may lead to significant
error in determinations of metals concentrations, suggesting
that analysis of both filtered and non-filtered samples should be
considered.
EQUIPMENT DECONTAMINATION
Contaminants on equipment that contacts ground water and
samples, including drilling equipment, well materials, sampling
devices, and sample bottles may be another source of sample
error. Error may be introduced by the addition of contaminants
to ground water or samples (contamination) or by the convey-
ance of ground water and/or contaminants from one sampling
installation or zone to another (cross-contamination). Cross-
contamination is most often a problem when equipment, particu-
larly sampling devices, is used portably but not properly cleaned
between installations. The process of cleaning equipment
before installation or after sampling is generally referred to as
decontamination.
Drilling equipment can be a source of gasoline, diesel fuel,
hydraulic fluid, lubricating oils and greases, and paint, all of
which can be introduced into the subsurface during drilling
operations. In addition, contaminated soil, scale, or water from
the site may enter the borehole directly or by adhering to drilling
pipe or other down-hole equipment. If these contaminants
originate from other sites or boreholes, cross-contamination
may result (Fetter, 1983). Steam cleaning is often recom-
mended as a method of decontaminating the drilling rig and
equipment before use and between boreholes. In addition,
placing down-hole drilling equipment on plastic sheeting or
other appropriate material while not in use may reduce contami-
nation from soils or other sources of contaminants at ground
surface.
Well casing and screen materials may contain residues of the
manufacturing process including cutting oils, cleaning solvents,
lubricants, and waxes (Aller et al., 1989). These residues must
be removed prior to well installation to prevent contamination or
other chemical impacts on samples. A procedure generally
recommended is to wash the casing in a strong detergent
solution followed by a tap water rinse (Barcelona et al., 1983;
Curran and Tomson, 1983) although steam cleaning or a high-
pressure hot water wash may be required for removal of some
oils, lubricants, and solvents (Alter et al., 1989).
Equipment used portably can lead to cross-contamination by
transferring water and contaminants from one installation to
another. In a survey of state and federal environmental regula-
tory agencies, Mickham et al. (1989) found that procedures for
decontamination of sampling equipment generally include a tap
water rinse, acid or solvent rinse (depending on type of contami-
nation), organic-free water rinse, and air drying. The survey also
showed that equipment that does not directly contact samples
is generally cleaned by detergent washes and steam cleaning.
These workers found little research into the effectiveness of
decontamination procedures.
16
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Korte and Keart (1985) suggest that high-volume pumping may
sufficiently clean sampling pumps. In contrast, field experi-
ments conducted by Matteoli and Noonan (1987) determined
that 90 minutes of pumping clean water through 200 feet o)
PTFE tubing was required to reduce the concentrations ol
several organic and inorganic constituents to below detection
levels. These workers found that the time required for effective
decontamination was generally related to the type of constitu-
ent. Freon was still detectable after 120 minutes of pumping.
The effects of cross-contamination can be reduced or elimi-
nated by utilizing equipment dedicated to individual monitoring
wells. As discussed previously, a potential disadvantage of this
approach may be interactions between the device and ground
water in the well between sampling events.
The use of plastic sample bottles may be another potential
source of contamination through leaching of organic and inor-
ganic constituents from the bottle materials (Gillham et al.,
1983). An experiment comparing acid-washed and water-
washed plastic sample containers determined that the risk of
contamination from trace elements in the bottles was greatest
for cadmium, copper, and zinc (Ross, 1986). In some cases
copper concentrations were 50 times higher in samples col-
lected in bottles that were not acid-washed. Moody and
Lindstrom (1977) suggested that plastic sample containers are
most effectively cleaned with rinses in both hydrochloric acid
and nitric acid to leach impurities from the plastics. Their study
further determined that, after acid-washing, PTFE and PE
containers were the least contaminating plastic or polymeric
materials.
Interference of ground-water sample chemistry may result from
direct introduction of foreign materials to ground water and
samples or from crosscontamination. Although it appears that
currently used decontamination procedures are adequate in a
general way, little research has been conducted to determine
the effectiveness of specific procedures for individual contami-
nants. Because they are not standardized, the contribution to
sample error of a particular procedure must be evaluated,
perhaps on a case-by-case basis.
To prevent crosscontamination when using sampling devices
portably, rinsate blanks (also referred to as equipment blanks)
should be collected to ensure the effectiveness of decontamina-
tion procedures. This may be accomplished by flushing or filling
the device with Type II reagentgrade water and collecting a
sample of the rinsate water. Analysis of rinsate blanks for the
contaminants being sampled will provide an indication of the
effectiveness of the deaning method (U.S. EPA, 1986) and
indicate if modifications of the procedures are required.
SAMPLE TRANSPORT AND STORAGE
Ground-water samples require proper containers, treatment,
transport, and storage to ensure the chemical and physical state
of the sample is preserved until analysis. Factors that could
potentially lead to error include volatilization, adsorption, diffu-
sion, precipitation, photodegradation, biodegradalion, and
cross-contamination (Parr et al., 1988). Methods developed,
and widely accepted, to minimize these effects are summarized
in U.S. EPA (1986) and Herzog et al. (1991).
To reduce the potential for bias during sample handling, appro-
priate chemical preservation of samples should take place
immediately upon collection. Increases in pH of 0.3 to 0.4 units
and declines in iron and zinc concentrations of several orders of
magnitude have been observed within seven hours of sample
collection (Schulleretal., 1981). These investigators also noted
slight declines in the concentrations of calcium, potassium,
magnesium, manganese, and sodium in unpreserved samples
within 48 hours of collection. To ensure immediate preservation,
it may be advisable in some cases to add chemical preserva-
tives to bottles immediately before sample collection. If this
method is utilized it is important to prevent the bottle from
overflowing which might cause the loss of some of the preser-
vative.
Plastic bottles are usually used for metals and major ions
samples to avoid the sorption effects that may occur with glass.
Most types of plastic bottles can be cleaned with hydrochloric
acid and nitric acid rinses which effectively leach impurities from
the material. PTFE and PE bottles tend to not leach impurities
to samples (Moody and Lindstrom, 1977) and therefore are the
easiest to dean and have the lowest potential to contaminate
samples. The quantities of impurities leached in these studies
are in the very low ng/cmJ range, generally below the levels in
most site investigations. Sorption of metals onto plastic bottles,
although normally not a problem, is reduced by acidifying the
sample and thereby keeping the metals ions m solution (Parr et
al., 1988). Clearly, if adequate cleaning is carried out and pre-
analysis holding times are not exceeded, contamination of
major ion and trace metal samples by sample bottles is unlikely.
Organic samples are usually placed in glass containers to avoid
the chemical interferences that may occur with plastic bottles.
The borosiRcate glass used in bottles for water samples for
organic analyses is easily cleaned and has very little potential for
contamination of samples or sorption from samples.
Cross-contamination of VOC samples during transport and
storage can be minimized if accepted procedures are carefully
followed. The evidence presently available indicates that cross-
contamination of VOC samples at concentrations typical of
hazardous waste sites is negligible under conditions normally
present during sample storage (Levine et al., 1983; Maskarinec
and Moody, 1988). Levine et al. (1983) did note, however, the
thickness of the PTFE lining under the VOC vial septum was
critical to the prevention of cross-contamination and that con-
tamination was evident when samples were stored near vials
containing saturated aqueous solutions of VOCs. Trip blanks
can be utilized to evaluate the potential for contamination of
samples during shipment to the laboratory. These blanks, which
consist of reagent-grade water in bottles of the same type used
for sampling, can be shipped to the site and laboratory in the
same shipping containers used for samples.
The length of time that a sample can be stored without degrada-
tion is related to the potential sources of error covered here. If
adequate measures are taken to reduce these errors, chemical
alteration of the sample during storage can be minimized. Using
commonly-accepted storage methods, concentrations of VOCs
have been shown to be stable afler 34 days (Friedman et al.,
1986) and 56 days (Maskarinec and Moody, 1988).
17
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ANALYTICAL TECHNIQUES
To gain perspective into the relative magnitude and importance
of errors introduced during ground-water sampling, it is useful to
quantify the errors involved in laboratory analysis. Potential
sources of error in the laboratory include glassware, reagents,
laboratory preparation techniques, and analytical equipment
and apparatus (Lewis, 1988). It is beyond the scope of this
document to discuss how each of these aspects of laboratory
operation can impact sample quality except to say that errors
can be detected and controlled by the use of various quality-
control checks. Vitale et al„ (1991) describe the blanks, dupli-
cate samples, and spikes that ensure the identification of
laboratory error. Through the use of these checks, analytical
errors often can be quantified, unlike many aspects of sampling
protocol where comparison to 'true' concentrations is usually
impossible.
In a review of the EPA Contract Laboratory Program (CLP)
database for gas chromatograph/mass spectrometer (GC/MS)
analysis of VOCs, Flotard et al. (1986) analyzed the deviations
in reported concentrations from actual concentrations in blind
performance evaluation samples. These deviations can be
considered measures of analytical errors, with underreported
concentrations considered negative error and overreported
concentrations considered positive error. The Flotard et al.
(1986) study found errors in reported concentrations of 22 VOCs
from -46.4% for 1,1-dichloroethane to +6.5% for bromoform.
The results for methylene chloride exhibited an apparent error
of +36.6% but this value was attributed to laboratory contamina-
tion of samples and not analysis error. Their review indicated
that 55% of the 22 evaluated VOCs resulted in reported concen-
trations that were more than 20% lower than actual concentra-
tions. Interlaboratory errors from 35 laboratories were found to
be from -3.9% to zero, although data from only three compounds
were analyzed.
A similar review of the CLP database for semi-volatile analyses
conducted by Wolff et al. (1986) concluded that the greatest
analytical errors were associated with phenolic compounds,
whose concentrations were consistently underreported. Other
classes of semi-volatiles showed no general trends. In that
study, analytical errors ranged from -48% for 1,3-dichloroben-
zene and 2,6-
-------
the potential for rigid PTFE, PVC, and metallic materials to
introduce error into concentrations of some trace metals and
hydrocarbon compounds. However, .little work has been con-
ducted under conditions simulating dynamic ground- or sample-
water flow or, more importantly, well-purging effects. Despite
these unresolved issues, materials' impacts can be minimized
by choosing well matenals compatible with the objectives of the
sampling program and the hydrogeologic and hydrochemical
conditions of the site. The proper choice of materials can reduce
chemical effects on water stored in the well between sampling
events and make removal of stagnant water during well purging
less difficult. When monitoring for low hydrocarbon concentra-
tions in non-corrosive ground water, SS and PVC casing may be
the most appropriate choices. Because PTFE has been shown
to introduce error into hydrocarbon determinations, it may be
most applicable under conditions where SS and PVC are not
considered appropriate. For example, SS would probably not be
considered an appropriate material in corrosive ground water or
where determinations of trace metal concentrations are of
primary concern. Likewise, PVC probably would not be consid-
ered an appropriate material in situations where solvents in
moderate to high concentrations might dissolve the PVC mate-
rial.
Flexible tubing can introduce significant error through sorption
of contaminants onto tubing material, leaching of constituents of
the tubing material into sampled water, and possibly transmis-
sion of organic compounds and gases through tubing walls.
These errors are generally greater than for rigid materials and
may be particularly important during site remediation efforts
when declines in ground-water concentrations may be masked
by desorption o1 previously sorbed compounds. Laboratory
research has demonstrated the potential for errors under static
conditions, but further research is required to understand how
sorption/desorption mechanisms can impact samples during
the dynamic sampling process. These studies suggest, how-
ever, that sample error can be minimized by substituting PTFE
for other types of flexible materials.
Filtration of samples for trace metals determinations may intro-
duce sample error either by the equipment and methods utilized
or by the actual decision tof ilter. Due to the presence of colloidal
sized particles in ground water, filtration can have dramatic
impacts on determinations of the concentrations of both mobile
and total dissolved metals. Indiscriminate filtration of metals
samples may lead to gross errors in these concentrations and
result in erroneous conclusions about ground-water transport of
metals. In view of this, the objectives of the sampling program
must be carefully considered before samples are filtered. If it is
decided to filter samples, in-line filtration with pre-cleaned, lower
pore-size filters can reduce errors associated with filtration.
In contrast to most aspects of the sampling process, errors
introduced during laboratory analysis may be relatively well
quantified. Analysis of the CLP database has shown errors in
reported concentrations of performance samples of -20% to
-30% for volatile and semivolatile compounds and -10% to zero
for inorganic constituents. Errors in analytical methods, as with
sample transport, sample storage, and equipment decontami-
nation, can be quantified for individual investigations by analyz-
ing standards and blind quality evaluation samples. Although
the magnitude of analytical error may be greater than the error
introduced during some aspects ol sample collection, analysis
of quality evaluation samples leads to easier identification and
quantification of analytical error.
Errors associated with other aspects of site investigations,
including well drilling and construction, are more difficult to
identify because true concentrations of hydrochemical constitu-
ents are unknown in field investigations. During the drilling
phase of site investigations, hydrogeologic disturbances can be
minimized by utilizing appropriate drilling methods. Likewise,
drilling-related hydrochemical disturbances can be reduced by
avoiding the use of fluids that might alter ground-water chemis-
try through ion exchange reactions or exposure to organic
polymers. Well construction and development methods appro-
priate to the site hydrogeologic conditions are capable of remov-
ing artifactsfrom the drilling process and improving the hydraulic
efficiency of the well with minimal impact on subsequent
samples. Proper design, installation, and isolation of cement or
bentonite seals reduces the potential for chemical alterations
from these materials. Any of these aspects of drilling and well
construction can lead to large errors if not carefully controlled,
however, the magnitude of error is directly related to site
conditions and the extent to which methods have been misap-
plied. Careful consideration and application of methods and
materials during well drilling and construction can significantly
reduce sample error.
Well purging method, purging rate, and the volume purged prior
to sample collection all possess great potential lor introducing
significant error when sampling for sensitive constituents. For
example, setting the purging device far below the air-water
interface and using a high purge rate may contaminate samples
by allowing stagnant waterto mix with sampled water. However,
it is possible to identify these potential sources of error and
modify purging procedures to minimize the errors. Conducting
a preliminary purge test may aid in identification of the depth and
rate that results in the most representative samples, however,
determination of when purging is complete (purge volume) may
be more difficult. Although purge volume can be calculated by
several indirect methods, this volume may not directly correlate
with the volume of water required to provide representative
samples. In particular, stabilization of the values of field chemi-
cal indicator parameters such as temperature, pH, and EC may
not coincide with stabilization of other hydrochemical param-
eters and constituents. Due to the often complex three-dimen-
sional distribution of many contaminants, concentrations of
individual constituents may not stabilize at the same time, or
may never stabilize. Despite these possibilities, the potential for
sample error can be reduced by choosing indicator parameters
that are sensitive to the purging process and relate to the
constituents of interest.
To reduce error when sampling for constituents that may be
associated with colloids, or other very sensitive constituents, it
is particularly important to minimize disturbance of the samples
and the sampling environment during the purging and sampling
process. To this end, reducing or eliminating purging, minimiz-
ing purging and sampling flow rates, and using dedicated
sampling devices placed within the well intake interval should all
be considered. Because this issue remains unresolved, general
recommendations are not possible and it may be necessary to
conduct preliminary purge tests to determine how indicator
19
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parameters and concentrations of important constituents vary
with purging rate, volume, method, and distribution of contami-
nants around the well. Inadequate determination of these
factors may lead to order-of-magnitude, or more, errors in
concentration determinations, especially in low-yield wells.
The errors most critical to sampling programs are those that are
difficult or impossible to identify because important conclusions
may be unknowingly based on erroneous or inadequate data.
Well location and design are aspects of sampling that are very
likely to produce undetected errors. Errors produced by well
location are virtually impossible to identify because their magni-
tude is entirely specific to that particular location. The appropri-
ate placement of a well can mean the difference between
detection of a contaminant plume or missing it entirely, so the
potential for error is virtually infinite. Even if a well is located in
the targeted zone of contamination or plume, little can be
deduced about small-scale hydrogeologic properties or con-
taminant distribution without a well-designed monitoring net-
work that accounts for individual site characteristics and pro-
gram objectives.
Well design, particularly the depth and interval of the well intake,
can also be a large potential source of undetectable errors. To
delineate the vertical distribution of contaminants at a single
location, samples must be collected at specific depths, hence,
wells must be screened over short intervals and adequately
sealed between sampling zones. Dilution and cross-contamina-
tion resulting from long-screened wells or poor well seals may
produce order-of-magnitude errors in concentrations that far
outweigh errors produced in all other aspects of the sampling
process. For example, dilution of samples collected from long-
screened remediation wells may mask true contaminant con-
centrations, leading to erroneous conclusions about the effec-
tiveness of remedial efforts.
In conclusion, it can be stated that virtually all aspects of ground-
water investigations, from well location to laboratory analysis,
have the potential to introduce error into the determinations of
concentrations of hydrochemical constituents. General defini-
tion of the magnitude of potential errors is difficult because
errors will be influenced by the ramplex interaction of geologic,
hydraulic, and hydrochemical conditions unique to each site, as
well as the design and performance of the sampling program.
Potential sources of error related to site conditions must be
identified during early phases of the remedial investigation (Rl)
and then minimized by careful design of the sampling program.
Modifications to the program design may then be necessary to
address issues that might arise as the Rl proceeds. Methods of
detecting errors that may be introduced during the performance
of the sampling program m ust be utilized so that these errors can
be identified and minimized. However, errors that are difficult or
impossible to detect may provide the greatest obstacles to the
collection of representative data.
TABLE 5. POTENTIAL SOURCES OF ERROR ASSOCIATED WITH ELEMENTS OF GROUND-WATER SAMPLING PROGRAMS
AT HAZARDOUS WASTE SITES.
Program Element Type of Error
Ability
to Avoid
Error Methods for Error Avoidance
Ability
to Detect
Error Method* for Error Detection
WeU Intake Length Long-screened and mufti- Easy to
screened weits may lead to Moderate
cross-contamination or
contamination dilution.
Well Intake Depth Well intake may miss zone Easy to
of imerest. Moderate
Well Intake Design Presence of particulates Easy to
in samples. Moderate
Filer Pack Presence of particulates in Easy to
samples. Reaction with filter Moderate
pack materials or introduced
contaminants may alter
hydrochemistry. Vertical
connection of naturaly
isolated zones if (Iter pack
too long. Invasion of borehole
seal materials if (iter pack
too short.
Identify specific zones of interest. Difficult
Use intake length appropriate to
program objectives and hydrogeologic
and hydrochemical conditions.
Identify specific zones of interest. Difficult
Use intake length appropriate to
program objectives and hydrogeo-
logic and hydrochemical conditions.
Design in conjunction with flter
pack for hydrogeologic conditions.
Compare with data from short-
screen wells or field-screening
methods.
Compare with data from other
wells or field-screening
methods.
Easy to Turbid samples.
Moderate
Design in conjunction with well Easy to
intake tor hydrogeologic conditions. Moderate
Use dean, non-reactive materials.
Instal with tremie pipe and measure
depths and volumes during instalation
to ensure correct placement.
Turbid samples.
Sorption/teaching studies of
materials before installation.
(Continued)
20
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TABLE 5. CONTINUED.
Program Element Type of Error
Ability
to Avoid
Error
Methods for Error Avoidance
Ability
to Detect
Error
Methods for Error Detection
Borehole Seals
Well Location
Drilling
Weft Development
Materials
If improperly placed, Moderate
'bentonite materials may alter
hydrochemistry through ion
exchange. If improperly
placed, cement may elevate
values of ground-water pH,
EC, alkalinity, calcium
concentration.
Inadequate coverage of Moderate
area' of investigation.
Depends on method. Moderate
Contamination by drilling or
other fluids may aler
hydrochemistry. Smearing
and mixing of fluids and
sediments at borehole
waH. Cross-contamination
within borehole.
Design for hydrogeologic conditions. Moderate
Isolate seals from sampling zone. to Difficult
Instal with tremie pipe and measure
depths and volumes during installation
to ensure correct placement.
Depends on method. Easy to
Incomplete development may Moderate
lead to turbid samples or poor
hydraulic efficiency. Alteration
of hydrochemistry by develop-
ment action. Introduction of
contaminants (including air
and water).
Depends on material, Easy to
contaminants, hydrochemical Moderate
conditions, and time of contact.
SorptionAJesorptionof
chemical constituents.
Leaching of constituents from
materials' matra. Biologic
activity. Possfcle transmission
through flex He materials.
Difficult
Moderate
to Difficult
Careful design ot monitoring well
network.
Careful consideration and application
of methods thai are appropriate for
program objectives and hydrogeologic
and hydrochemical conditions.
Minimize use of water-based drilling
fluids and additives. If constituents
sensitive to atmospheric exposure wil
be sampled, minimize use of air-based
drilling fluids. Determine the chemical
• quality of driling fluids used. Use
appropriate development methods to
minimize impacts of drilSng.
Careful consideration and application Moderate
of methods that are appropriate for
program objectives and hydrogeologic
and hydrochemical conditions. Avoid
adding fluids to wel. If adding fluids is
necessary, determine the chemical
quality of the fluids used.
Select materials that are appropriate Difficult
for program objectives and hydro-
geologic and hydrochemical conditions.
Use appropriate wel purging techniques.
Bentonite: High sodium con-
centrations if sodium bentonite
used and samples are highly
contaminated. Cement:
Sarfiple pH over 10, and high
EC, alkalinity, and calcium
concentrations.
Compare with data trom
nearby wells or field-
screening methods.
Drilling fluid contamination:
Depends on composition of
fluid. Compare with data from
nearby wells and field-
screening methods. Evaluate
chemical quality of fluids used.
Tutbid samples and production
of sedments during pumping
may indicate incomplete
development or inadequate
design ol filter pack and weU
intake. It fluids were added,
evaluate chemical quality of
fluids used.
Sorption/leaching studies of
materials before installation.
Detection after installation
depends on material,
contaminants, hydrochemical
conditions, and time of contact.
(Continued)
21
-------
TABLE 5. CONTINUED.
Program Elament Type of Error
Ability
to Avoid
Error
Methoda for Error Avoldanca
Ability
to Detect
Error
Methods for Error Oetactlon
Well Purging
Sampling Device
Sample Col taction
Time and Depth
Sample FKration
Incomplete removal of
stagnant water (water
affected by contact with
atmosphere and well and
sampling device materials).
Disturbance of ambient
hydrochemical conditions.
Depends on operating
princple of sampling device.
Sorption, desorption, and
leaching from materials.
Degassing or volatiization
from sample. Atmospheric
contamination.
Mixing with stagnant water
in well. As time after purging
increases, water in well
becomes more stagnant.
Type of filer system used
and length ot pre-litrafon
holding time determines
extent of temperature
changes, atmospheric
contamination, degassing,
and sorption onto particulates.
Filer pore size may ailed
passage of certain constituents
and suspended material.
Filar materia) and tiller pre-
dearang may affect results.
Erroneous conclusions about
metals concentrations may
result trom association o<
metals with colloids.
Easy to Choose indicator parameters that are Easy to
Moderate sensitive to purging process and relate Moderate
(Moderate to the chemical constituents of interest. (Moderate
to Difficult Conduct purge-volume lest to determine to Difficult
under when parameters or constituents of under
low-yield interest reach stable values. Determine low-yield
conditions) if low flow-rate and/or low volume conditions)
purging is appropriate. If not, minimize
volume of stagnant water above device
intake by purging near water surface or
lower device during purging or before
sampling. Avoid drawing water level
below top of wet intake.
Easy Select device that is appropriate for Moderate
sample type, hydrochemical conditions, to Difficult
and program objectives.
Easy Collect samples from within or im- Moderate
mediately above well intake. Use to Difficult
appropriate sampling rale. Avoid
moving sampler within water column
during sampling. High-yield wells:
Sample immediately after purging.
Low-yield wells: Determine
appropriate time based on response
ol wefl and purge-volume test.
Easy to Determine of filtration is necessary Moderate
Moderate tor the objectives of the program.
Minimize pre-fillration holding time.
Use pre-deaned in-line filters. Some
situations may warrant use of pore
sizes other than 0.45^jn.
Conduct purge-volume test to
determine when parameters or
constituents of interest reach
stable values
Depends on sampler type.
Compare with data collected
with other devices.
Test different scenarios and
compare results, although may
be very difficult to determine
which results are the most
representative.
Compare analytical results of
tillered and unaltered samples.
Compare analytical results ot
different filtration methods.
(Continued)
22
-------
TABLE 5. CONTINUED.
Program Element Typ« of Error
Ability
to Avoid
Error
Methods for Error Avoidants
Ability
to Detect
Error
Methods for Error Detection
Equpment
Decontamination
Sample Preservation
Sample Transport
and Storage
Cross-contamination
between wells if sampling
equipment is used port ably.
Incomplete removal of
residues from manufacture
or contaminants from
storage, transport, or use.
Changes in hydrochemistry
during sample shipment
and storage.
Cross-contaminalion
between sample bottles.
Material effects from
sample bottles. Loss of
volatile constiuents.
Easy Use appropriate cleaning and
decontamination procedures.
Easy
Easy Use appropriate physical and
chemical preservation procedures.
Easy Use appropriate sample bottle type
and deaning procedure.
Do not exceed sample holding times.
Moderate
lo difficult.
Easy
Collect rinsate blanks after
deaning.
Indirectly identified by
evaluating how well
procedures are being
foiowed.
Transport trip blanks with
samples.
Laboratory Analysis Deviation from true
concentrations.
Moderate Use appropriate analytical methods
and laboratory procedures.
Easy to Analyze blind performance
Moderate evaluation samples, blanks,
and standards.
23
-------
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27
~ u.S. GOVERNMENT PtUNTING OfTlCt: l*»l • 750-002/MIOI
-------
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United States
Environmental Protection Agency
Center lor Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
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-------
United States Office of Office of Solid EPA/540/4-91/001
Environmental Protection Research and Waste February 1991
Agency Development and Emergency
Refnonse
&EPA Ground-Water Issue
SOIL SAMPLING AND ANALYSIS FOR
VOLATILE ORGANIC COMPOUNDS
T. E. Lewis, A. B. Crockett, R. L. Siegrist, and K. Zarrabi
The Regional Superfund Ground Water Fo-
rum is a group of ground-water scientists that
represents EPA's Regional Superfund Of-
fices. The forum was organized to exchange
up-to-date information related to ground-
water remediation at Superfund sites. Sam-
pling of soils for volatile organic compounds
(VOCs) is an issue identified by the Ground
Water Forum as a concern of Superfund de-
cision makers.
A group of scientists actively engaged in
method development research on soil sam-
pling and analysis for VOCs gathered at the
Environmental Monitoring Systems Labora-
tory in Las Vegas to examine this issue.
Members of the committee were
R. E. Cameron (LESC), A. B. Crockett
(EG&G), C. L. Gerlach (LESC), T. E. Lewis
(LESC), M. P. Maskarinec (ORNL),
B. J. Mason (ERC), C. L. Mayer (LESC),
C. Ramsey (NEIC), S. R. Schroedl (LESC),
R. L. Siegrist (ORNL), C. G. Urchin (Rutgers
University), L. G. Wilson (University of
Arizona), and K. Zarrabi (ERC). This paper
was prepared by The Committee for EMSL-
LV's Monitoring and Site Characterization
Technical Support Center, under the direction
of T. E. Lewis, with the support of the
Superfund Technical Support Project. For
further information contact Ken Brown, Center
Director at EMSL-LV, FTS 545-2270, or T. E.
Lewis at (702) 734-3400.
PURPOSE AND SCOPE
Concerns over data quality have raised many
questions related to sampling soils for VOCs.
This paper was prepared in response to some
of these questions and concerns expressed
by Remedial Project Managers (RPMs) and
On-Scene Coordinators (OSCs). The follow-
ing questions are frequently asked:
1. Is there a specific device suggested for
sampling soils for VOCs?
2. Are there significant losses of VOCs when
transferring a soil sample from a sampling
device (e.g., split spoon) into the sample
container?
3. What is the best method for getting the
sample from the split spoon (or other
device) into the sample container?
4. Are there smaller devices such as
subcore samplers available for collecting
aliquots from the larger core and effi-
ciently transferring the sample into the
sample container?
5. Are certain containers better than others
for shipping and storing soil samples for
VOC analysis?
6. Are there any reliable preservation proce-
dures for reducing VOC losses from soil
samples and for extending holding times?
This paper is intended to familiarize RPMs,
OSCs, and field personnel with the current
state of the science and the current thinking
concerning sampling soils for VOC analysis.
Guidance is provided for selecting the most
effective sampling device for collecting
^ I acftrology *£
o A z
O ^uppo" CD
X'~°J
^ OGY^
Superfund Technology Support Center
for Monitoring and Site Characterization
Environmental Monitoring Systems
Laboratory Las Vegas, NV
Technology ImwaSon CMtee
Office of Solid Waste and Emergency Response,
U.S. EPA, Washington, D.C.
Waiter W. Kovalick, Jr, Ph.D., Director
Printed on Recycled Paper
-------
samples from soil matrices. The techniques for sample collec-
tion, sample handling, containerizing, shipment, and storage
described in this paper reduce VOC losses and generally
provide more representative samples for volatile organic analy-
ses (VOA) than techniques in current use. For a discussion on
the proper use of sampling equipment the reader should refer
to other sources (Acker, 1974; U.S. EPA, 1983; U.S. EPA,
1986a).
Soil, as referred to in this report, encompasses the mass
(surface and subsurface) of unconsolidated mantle of weath-
ered rock and loose material lying above solid rock. Further, a
distinction must be made as to what fraction of the unconsoli-
dated material is soil and what fraction is not. The soil compo-
nent here is defined as all mineral and naturally occurring
organic material that is 2 mm or less in size. This is the size
normally used to differentiate between soils (consisting of
sands, silts, and clays) and gravels.
Although numerous sampling situations may be encountered,
this paper focuses on three broad categories of sites that might
be sampled for VOCs:
1. Open test pit or trench
2. Surface soils (< 5 ft in depth)
3. Subsurface soils (> 5 ft in depth)
INTRODUCTION
VOCs are the class of compounds most commonly encoun-
tered at Superfund and other hazardous waste sites (McCoy,
1985; Plumb and Pitchford, 1985; Plumb, 1987; Ameth et al.,
1988). Table 1 ranks the compounds most commonly encoun-
tered at Superfund sites. Many VOCs are considered hazard-
ous because they are mutagenic, carcinogenic, or teratogenic,
and they are commonly the controlling contaminants in site
restoration projects. Decisions regarding the extent of contami-
nation and the degree of cleanup have far-reaching effects;
therefore, it is essential that they be based on accurate mea-
surements of the VOC concentrations present. VOCs, how-
ever, present sampling, sample handling, and analytical diffi-
culties, especially when encountered in soils and other solid
matrices.
Methods used for sampling soils for volatile organic analysis
(VOA) vary widely within and between EPA Regions, and the
recovery of VOCs from soils has been highly variable. The
source of variation in analyte recovery may be associated with
any single step in the process or ail steps, including sample
collection, transfer from the sampling device to the sample
container, sample shipment, sample preparation for analysis,
and sample analysis. The strength of the sampling chain is only
as strong as its weakest link; soil sampling and transfer to the
container are often the weakest links.
Sample collection and handling activities have large sources of
random and systematic errors oompared to the analysis itself
(Barcelona, 1989). Negative bias (i.e., measured value less
than true value) is perhaps the most significant and most
difficult to delineate and control. This error is caused primarily
by loss through volatilization during soil sample collection,
storage, and handling.
TABLE 1. RANKING OF GROUND WATER CONTAMINANTS BASED
ON FREQUENCY OF DETECTION AT 358 HAZARDOUS WASTE
DISPOSAL SITES
Contaminant Detection Frequency
Tnchloroethene (V)
51.3
Tetrachloroethene (V)
36.0
1,2-trans Dichloroethene (V)
29.1
Chloroform (V)
28.4
1,1-Dichloroethene (V)
25.2
Methylene chloride (V)
19.2
1,1,1 -Trichloroethane (V)
18.9
1,1-Dichloroethane (V)
17.9
1,2-Dichloroethane (V)
14.2
Phenol (A)
13.6
Acetone (V)
12.4
Toluene (V)
11.6
bis-(2-Ethylhexyl) phthaJate (B)
11.5
Benzene (V)
11.2
Vinyl chloride
8.7
V = volatile, A = acid extractabte, B = base/neutral
Source: Plumb and Pitchford (1985).
There are currently no standard procedures for sampling soils
for VOC analyses. Several types of samplers are available for
collecting intact (undisturbed) samples and bulk (disturbed)
samples. The selection of a particular device is site-specific.
Samples are usually removed from the sampler and are placed
in glass jars or vials that are then sealed with Teflon-lined caps.
Practical experience and recent field and laboratory research,
however, suggest that procedures such as these may lead to
significant VOC losses (losses that would affect the utility of the
data). Hanisch and McDevitt (1984) reported that any
headspace present in the sample container will lead to desorp-
tion of VOCs from the soil particles into the headspace and will
cause loss of VOCs upon opening of the container. Siegrist and
Jennsen (1990) found that 81% of the VOCs were lost from
samples containerized in glass jars sealed with Teflon-lined
caps compared to samples immersed in methanol in jars.
FACTORS AFFECTING VOC RETENTION AND
CONCENTRATION IN SOIL SYSTEMS
Volatile organic compounds in soil may coexist in three phases:
gaseous, liquid (dissolved), and solid (sorbed). [Note: "Sorbed"
is used throughout this paper to encompass physical and
chemical adsorption and phase partitioning.] The sampling,
identification, and quantitation of VOCs in soil matrices are
complicated because VOC molecules can coexist in these
2
-------
three phases The interactions between these phases are
illustrated in Figure 1. The phase distribution is controlled by
VOC physicochemical properties (e.g., solubility, Henry's
constant), soil properties, and environmental variables (e.g.,
soil temperature, water content, organic carbon content).
z
o
F
a.
oc
O
Cfl
VOLATILIZATION
E
h.
9
r.
o
¦«
3
E
~9
C
3
Temperature,
wind, humidity,
hydrodynamics,
baro metre
pressure,
surface features.
EXTERNAL
FACTORS
SORPTION
q = KPcw
(Linear Isotherm)
Temperature,
hydrodynamics,
surface features.
Figure 1. Equilibrium relationships for phase partitioning of
VOCs in soil systems. See Table 2 for definitions
of abbreviations.
The factors that affect the concentration and retention of VOCs
in soils can be divided into five categories: VOC chemical
properties, soil chemical properties, soil physical properties,
environmental factors, and biological factors. A brief summary
of VOC, soil, and environmental factors is presented in Table 2,
which provides an overview of the factors that interact to control
VOCs in the soil environment at the time a sample is collected.
The cited references provide a more detailed discussion. The
chemical and physical properties of selected VOCs are further
described in Table 3. Note that many of these properties have
been determined in the laboratory under conditions (e.g.,
temperature, pressure) that may differ from those encountered
in the field. Devitt et al. (1987) offers a more exhaustive list.
Many VOCs exhibit extreme mobilities, particularly in the vapor
phase, where their gas diffusion coefficients can be four times
greater than their liquid diffusion coefficients. The vapor phase
migration is influenced by the moisture content of the soil which
alters the air-filled to water-filled pore volume ratio. The reten-
tion of VOCs by soil is largely controlled by reactions with the
solid phase. This retention is especially true for the finer
particles of silts and clays. The fine-grained particles (<2 mm)
have a large surface-to-volume ratio, a large number of reactive
sites, and high sorption capacities (Richardson and Epstein,
1971; Boucher and Lee, 1972; Lotse et al., 1968). Some
investigators attribute the greater sorption of VOCs onto fine-
grained particles to the greater organic carbon content of
smaller particles (Karickhoff etal., 1979).
Soil-moisture content affects the relative contributions of min-
eral and organic soil fractions to the retention of VOCs (Smith
et al., 1990). Mineral clay surfaces largely control sorption when
soil moisture is extremely low (<1%), and organic carbon
(Continued on page 7)
TABLE 2. FACTORS AFFECTING VOC CONCENTRATIONS IN SOILS
Factor
Common
Abbr.
Units
Effects on VOC Concentrations in Soil
References
VOC Chemical Properties
Solubility
Henry's Constant
Vapor pressure
Organic caibon part, coeff.
Octanol/water part, coeff.
Boiling point
Soil/water distribution
coefficient
mg/L
K„ (atm-mJ)/mole
v.p.
K„
bp-
mm Hg
mg VOC/g C
mg VOC /
mgoctanol
°C
[1]
Affects fate and transport in water, effects
water/air partit., influences organic caibon partit.
Constant of proportionality between the water and gas
phase concentrations; temperature and pressure dependent.
Affects rate of loss from soil.
Adsorption coefficient normalized for soil organic content.
Equilibrium constant for distribution of VOC between water
and an organic (octanol) phase. Gives estimate of VOC
partitioning into organic fraction of soil.
Affects co-evaporation of VOC and water from soil surface.
Equilibrium constant for distribution of contaminant between
solid and liquid phases.
Roy and Griffin (1985)
Shen and Sewell (1982)
Spencer etal. (1988)
Shen and Sewell (1982)
Farmer etal. (1980)
Voice and Weber (1983)
Voice and Weber (1983)
Voice and Weber (1983)
(Continued)
3
-------
TABLE 2. (CONTINUED)
Factor
Common
Abbr. Units
Effects on VOC Concentrations In Soil
References
Soil Chemical Properties
Cation exchange capacity CEC meq/100g
Ion concentration
(activity)
pH -log[H*]
Total organic cartxin content TOC mg CJg soil
Soil Physical Properties
Particie size or texture A
Specific surface area s.a.
Bulk density p,
Porosity n
Percent moisture 0
Water potential pF
Hydraulic conductivity K
% sand,
silt, day
mVg
g/cm3
%
% (w/w)
m/d
Estimates the number of negatively charged sites on soil
particles where charged VOC may sorb; pH dependent.
Influences a number of soil processes that involve
non-neutral organic partitioning; affects CEC and
soliAiiity of some VOCs.
An important partitioning medium for non-polar, hydrophobic
(high KJ VOCs; sorption of VOCs in this medium may be
highly irreversible.
Affects infiltration, penetration, retention, sorption, and
mobility of VOCs. Influences hydraulics as well as surface-
area-to-volume ratio (s.a.°cKd).
Affects adsorption of VOCs from vapor phase; affects soil
porosity and other textural properties.
Used in estimating mobility and retention of VOCs in soils;
will influence soil sampling device selection.
Void volume to total volume ratio. Affects volume,
concentration, retention, and migration of VOCs in soil voids.
Affects hydraulic conductivity of soil and sorption of VOCs.
Determines the dissolution and mobility of VOCs in soil.
Relates to the rate, mobility, and concentration of VOCs
in water or liquid chemicals.
Affects viscous flow of VOCs in soil water depending on
degree of saturation, gradients, and other physical factors.
Chiou et al. (1988)
Farmer etal. (1980)
Richardson and
Epstein (1971)
Karickhoff et al. (1979)
Spencer et al. (1988)
Farmer etal. (1980)
Shen and Sewell (1982)
Farmer et al. (1980)
Chiou and Shoup (1985)
Environmental Factors
Relative humidity
Temperature
Barometric pressure
R.H.
T
%
°C
mm Hg
Couid affect the movement, diffusion, and concentration of
VOCs; interrelated factors; could be site specific and dependent
upon soi surface - air interface dfferentials.
Chiou and Shoup (1985)
Wind speed
Ground cover
knots Relevant to speed, movement, and concentration of
VOCs exposed, removed, or diffusing from soil surface.
% Intensity, nature, and kind, and distribution of cover
could affect movement, dffiusion rates, and
concentration of VOCs.
4
-------
TABLE 3. CHEMICAL PROPERTIES OF SELECTED VOLATILE ORGANIC COMPOUNDSf
Compound
m.w.
(g/mole)
Solubilities
(mg/L @ 20°C)
iogtV
logKj
Vapor Pressure
(mm @ 20°C)
Acetone
58
Miscible
-0.22
-0.24
270 (@30°)
Benzene
78
1780
1.91
2.11
0.22
76
Bromodichloromethane
164
7500
2.18
2.10
50
Bromoform
253
3190 (@30°)
6 (@ 25°)
Bromomethane
95
900
1.34
1.19
1.50
1250
2-Butanone
72
270000
1.56
0.26
76
Carbon disulfide
76
2300
1.80
260
Cartoon tetrachloride
154
800
2.04
2.64
0.94
90
Chlorobenzene
113
500
2.18
2.84
0.16
9
Chloroethane
65
5740
1.40
1.54
0.61
1000
2-Chloroethyivinyl ether
107
Chloroform
120
8000
1.46
1.97
0.12
160
Chloromethane
51
8348
0.78
0.91
1.62
3800
Dibromochloromethane
208
3300
2.45
2.24
15 (@10.5°)
1,2-Dichlorobenzene
147
100
2.62
3.38
1
1,3-Dichlorobenzene
147
123 (@ 25°)
3.38
1,4-Dichlorobenzene
147
49 (@ 22°)
3.39
1
1,1 -Dichloroethane
99
5500
1.66
1.79
0.18
180
1,2-Dichloroethane
99
8690
1.34
1.48
0.04
61
1,1 -Dichloroethene
97
400
500
trans-1,2-Dichloroettiene
97
. 600
1.56
2.06
200 (@14°)
1,2-Dichloropropane
113
2700
1.99
42
cis-1,3-Dichloropropene
110
2700
34 (@ 25°)
trans-1,3,-Dichloropropene
111
2800
43 (@ 25°)
Ethylbenzene
106
152
2.60
3.15
7
2-Hexanone
100
3500
1.38
2
Methylene chloride
85
20000
1.40
1.25
349
Methylisobutylketone
100
17000
1.34
1.46
0.002
6
Perch loroethylene
166
150
2.60
2.60
0.85
14
Styrene
104
300
2.61
2.95
5
1,1,2,2-Tetrachloroethane
166
2900
2.07
2.60
5
Tetrachlcroethene
166
150
2.78
3.40
18 (@25°)
Toluene
92
515
2.18
2.69
0.27
22
1,1,1-Triqhloroethane
133
4400
2.19
2.50
1.46
100
1,1,2-Trichloroethane
133
4500
2.14
2.07
19
Trichloroethylene
132
700
2.09
2.29
0.37
60
Trichlorofiuoromethane
137
1100 (@25°)
2.68
687
Vinyl acetate
86
25000
1.59
0.73
115 (@25°)
Vinyl chloride
63
1100 (@25°)
2.60
1.38
97.0
2660 (@25°)
Total xylenes
106
198
2.46
9400.0
' From Verschueren 1983, Jury 1984.
' Organic carbon partitioning coefficient.
' Octanol/walaf partitioning coefficient
c Henrys Gas Law constant (dmenaonless) @ 20°C.
5
-------
TABLE 4. MICROBIOLOGICAL FACTORS AFFECTING VOCs IN SOIL SYSTEMS
Organism(s)
Compound(s)
Conditions Remarks/metabolites)
Various soil microbes Pentachlorophenol Aerobic
1,2,3- and 1,2,4-Trichlorobenzene Aerobic
tetra-, tn-, di-, and m-Chiorophenol (Kobayashi and Rittman, 1982)
2,6-; 2,3-Dichlorobenzene; 2,4- and 2,5-dichlorobenzene; C02
(Kobayashi and Rittman, 1982)
Various soil bacteria
Trichloroe thane, trichioromethane,
methylchloride, chloroe thane,
dichloroethane, vinylidiene chloride,
tnchloroethene, tetrachloroethene,
methylene chloride,
dibromochloromethane,
bromochlorome thane
Anaerobic Reductive dehalogenation under anoxic conditions, (i.e., < 0.35 V)
(Kobayashi and Rittman, 1982)
Various soil microbes Tetrachloroethene
Anaerobic Reductive dehalogenation to tnchloroethene,dichloroethene, and
vinyl chloride, and finally C02 (Vogel and McCarty, 1985)
Vanous soil microbes ,3C-labeled tnchloroethene
Anaerobic Dehalogenation to 1,2-dichloroethene and not 1,1 -dichloroethene
(Kleopfer et al., 1985)
Various soil bacteria Trichloroethene
Aerobic Mineralized to C02 in the presence of a mixture of natural gas
and air
Actinomycetes
chlorinated and non-chlorinated
aromatics
aerobic Various particle breakdown products mineralized by other
microorganisms (Lechevalier and Lechevalier, 1976)
Fungi
DDT
Aerobic Complete mineralization in 10-14 days (Johnsen, 1976)
Pseudomonas sp.
Acmetobaciersp.
Micrococcus sp.
Aromatics
Aerobic Organisms were capable of sustaining growth in these compounds
with 100% biodegradation (Jamison et al., 1975)
Acetate-grown biofilm Chlorinated aliphatics
Chlorinated and nonchlonnated
aromatics
Aerobic No biodegration observed (Bouwer, 1984)
Methanogenic Nearly 100% biodegradation observed (Bouwer, 1984)
Aerobic Nearly 100% biodegradation (Bouwer, 1984)
Methanogenic No biodegration observed (Bouwer, 1984)
Blue-green algae
(cyanobacteria)
Oil wastes
Aerobic Biodegradation of automobile oil wastes, crankcase oil, etc.
(Cameron, 1963)
6
-------
partitioning is favored when moisture content is higher (Chiou
and Shoup, 1985).
Biological factors affecting VOC retention in soil systems can be
divided into microbiological and macrobiological factors. On the
microbiological level, the indigenous microbial populations
present in soil systems can alter VOC concentrations. Although
plants and animals metabolize a diversity of chemicals, the
activities of the higher organisms are often minor compared to
the transformations affected by heterotrophic bacteria and fungi
residing in the same habitat. The interactions between environ-
mental factors, such as dissolved oxygen, oxidation-reduction
potential (Eh), temperature, pH, availability of other compounds,
salinity, particulate matter, and competing organisms, often
control biodegradation. The physical and chemical characteris-
tics of the VOC, such as solubility, volatility, hydrophobicity, and
also influence the ability of the compound to biodegrade.
Table 4 illustrates some examples of the microbiological alter-
ations of some commonly encountered soil VOCs. In general,
the halogenated alkanes and alkenes are metabolized by soil
microbes under anaerobic conditions (Kobayashi and Rittman,
1982; Bouwer, 1984), whereas the halogenated aromatics are
metabolized under aerobic conditions. To avoid biodegradation
and oxidation of VOCs in soils, scientists at the U.S. EPA Robert
S. Kerr Environmental Research Laboratory in Ada, OK, extrude
the sample in a glove box.
On a macro scale, biological factors can influence the migration
of VOCs in the saturated, vadose, and surface zones (Table 5).
Biofilms may accumulate in the saturated zone and may biode-
grade and bioaccumulate VOCs from the ground water. The
biofilm, depending on its thickness, may impede ground-water
flow. Plant roots have a complex microflora associated with
TABLE 5. MACROBIOLOGICAL FACTORS AFFECTING VOCs
IN SOIL SYSTEMS
Factor
Zone
Effects
Biofilms
Saturated
Plant roots
Animal burrows
holes
Capillary fringe
to vadose
Vadose
Vegetative cover Soil surface
Biodegradation, bioaccumulation,
formation of metabolites that are
more or less toxic than parent
compound, thick biofilm may
retard saturated flow
Mycorrihizal fungi may biodegrade
or bioaccumulate VOC, root
channels may serve as conduits
for VOC migration
May act as entry point for and
downward migration of surface
spills and serve as conduit for
upward VOC migration
Serve as barrier to volatilization
from soil surface and retard
infiltration of surface spills
them known as mycorrhizae. The mycorrhizae may enhance
VOC retention in the soil by biodegradation or bioaccumulation.
The root channels may act as conduits for increasing the
migration of VOCs through the soil. Similarly, animal burrows
and holes may serve as paths of least resistance for the
movement of VOCs through soil. These holes may range from
capillary-size openings, created by worms and nematodes, to
large-diameter tunnels excavated by burrowing animals. These
openings may increase the depth to which surface spills pen-
etrate the soil. A surface covering consisting of assorted vegeta-
tion is a significant barrier to volatilization of VOCs into the
atmosphere. Some ground-water and vadose-zone models
(e.g., RUSTIC) include subroutines to account for a vegetative
cover (Dean et al., 1989).
SOIL SAMPLING AND ANALYSIS DESIGN
Prior to any sampling effort, the RPM or OSC must establish the
intended purpose of the remedial investigation/feasibility study
(RI/FS). The goals of collecting samples for VOA may include
source identification, spill delineation, fate and transport, risk
assessment, enforcement, remediation, or post-remediation
confirmation. The intended purpose of the sampling effort drives
the selection of the appropriate sampling approach and the
devices to be used in the investigation.
The phase partitioning of the VOC can also influence which
sampling device should be employed. Computer models gener-
ally are used only at the final stages of a RI/FS. However,
modeling techniques can be used throughout the RI/FS process
to assist in sampling device selection by estimating the phase
partitioning of VOCs. The RPM is the primary data user for a Rl/
FS led by a federal agency. As such, the RPM must select the
sampling methodology to be employed at the site. Figure 2
illustrates the sequence of events used to plan a VOC sampling
and analysis activity.
The domains of interest also must be determined. The target
domains may include surface (two dimensions) or subsurface
(three dimensions) environments, hot spots, a concentration
greater or less than an action limit, or the area above a leaking
underground storage tank. Statistics that may be generated
from the target domain data must be considered before a
sample and analysis design is developed. Possible statistics of
interest may include average anaiyte concentration and the
variance about the mean (statistics that compare whether the
observed level is significantly above or below an action level) as
well as temporal and spatial trends. Data must be of sufficiently
high quality to meet the goals of the sampling activity. The level
of data quality is defined by the data quality objectives (DQOs).
In RI/FS activities, sites are so different and information on
overall measurement error (sampling plus analytical error) is so
limited that it is not practical to set universal or generic precision,
accuracy, representativeness, completeness, and comparabil-
ity (PARCC) goals. The reader is referred to a user's guide on
quality assurance in soil sampling (Barth et al., 1989) and a
guidance document for the development of data quality objec-
tives for remedial response activities (U.S. EPA, 1987).
DQOs are qualitative and quantitative statements of the level of
uncertainty a decision maker is willing to accept in making
decisions on the basis of environmental data. It is important to
realize that if the error associated with the sample collection or
7
-------
DEFINE
GOAL
Soil population
• Location
Statistics
• Trend
• x, Std. dev.
• Comparison
Purpose
• Enforcement
• Remediation
• Source ID
SET
DQOs
CHARACTERIZE
SITE
History
Process
Soil properties
Soil conditions
Existing data
Environmental
factors
~ DESIGN
MINIMIZE RESOURCES
Confidence
level
Bias
Precision
Action level
Analyte level
ANALYTE
OF INTEREST
SELECT
TOOLS
MAXIMIZE INFORMATION MAXIMIZE QUALITY
NO
FEASIBLE
YES
Refine draft S&A Plan
to meet goals
ON-SITE DATA
Field analysis
Visual
observations
Odors
Population
accesibility
]
L-
CONSTRAINTS
Personnel
Budget
Time
Politics
FIELD
IMPLEMENTATION
DATA EVALUATION
DRAFT
S&A PLAN
Tools
Analytical methods
Holding times
No. of samples
Sample mass
Decontamination
QA/QC
Field analysis
Handling
Random/
systematic design
OBJECTIVE^
MET
NO
Figure 2. Flowchart for planning and implementation of a soil sampling and analysis activity.
8
-------
preparation step is large, then the best laboratory quality
assurance program will be inadequate (van Ee et al., 1990).
The greatest emphasis should be placed on the phase that
contributes the largest component of error. For the analysis of
soils for VOCs, the greatest sources of error are the sample
collection and handling phases.
The minimum confidence level (CL) required to make a
decision from the data is defined by the DQOs. The minimum
CL depends on the precision and accuracy in sampling and
analysis and on the relative analyte concentration. Relative
error may be reduced by increasing either the number or the
mass, of the samples to be analyzed. For instance, although
5-g aiiquots collected in the field might exhibit unacceptable
errors, 100-g samples will yield smaller errors and might
therefore meet study or project requirements. Compositing soil
samples in methanol in the field also can reduce variance by
attenuating short-range spatial vanability.
Field sampling personnel should coordinate with laboratory
analysts to ensure that samples of a size appropriate to the
analytical method are collected. For example, if the laboratory
procedure for preparing aiiquots calls for removing a 5-g
aliquot from a 125-mL wide-mouth jar, as per SW-846, Method
8240 (U.S. EPA 1986b), then collecting a larger sample in the
field will not reduce total measurement error, because addi-
tional errors will be contributed from opening the container in
the laboratory and from subsequent homogenization.
Aliquoting of a 5-g sample in the field into a 40-mL VOA vial that
can be directly attached to the laboratory purge-and-trap unit
significantly reduces loss of VOCs from the sample (U.S. EPA,
1991a). Significant losses of VOCs were observed when
samples were homogenized as per Method 8240 specifica-
tions. Smaller losses were observed for smaller aiiquots (1 to
5 g) placed in 40-mL VOA vials that had modified caps that
allowed direct attachment to the purge-and-trap device. The
procedure of collecting an aliquot in the field eliminates the
need for sample preparation and eliminates subsequent VOC
loss in the laboratory.
Field-screening procedures are gaining recognition as an
effective means of locating sampling locations and obtaining
real-time data. The benefits of soil field-screening procedures
are: (1) near real-time data to guide sampling activities, (2)
concentration of Contract Laboratory Program (CLP) sample
collection in critical areas, (3) reduced need for a second visit
to the site, and (4) reduced analytical load on the laboratory.
Limitations of field-screening procedures are: (1) a priori
knowledge of VOCs present at the site is needed to accurately
identify the compounds, (2) methodologies and instruments
are in their infancy and procedures for their use are not well
documented and (3) a more stringent level of quality assur-
ance and quality control (QA/QC) must be employed to ensure
accurate and precise measurements. The potential benefits
and limitations associated with soil-screening procedures
must be carefully weighed and compared to the DQOs.
Certain sampling and analytical methods have inherent limita-
tions on the type of QA/QC that is applicable. For example,
splitting soil samples in the field would not be appropriate for
VOA due to excessive analyte loss. The higher the minimum
CL needed to make a decision, the more rigorous the QA/QC
protocols must be. As VOC concentrations in the soil sample
approach the action or detection limit, the quantity and fre-
quency of QA/QC samples must be increased, or the number of
samples must be increased, to ensure that the data quality
obtained is appropriate to satisfy project objectives.
One critical element in VOC analysis is the appropriate use of trip
blanks. If a sample consists of a silty clay loam, a trip blank of
washed sand may not be realistic, for such a blank would not
retain VOC cross contaminants in the same way as the sample.
The trip blank soil matrix should have a sorptive capacity
similar to the actual sample. In addition, high-
concentration and low-concentration samples should be shipped
in separate coolers.
DEVICE SELECTION CRITERIA
The selection of a sampling device and sampling procedures
requires the consideration of many factors including the number
of samples to be collected, available funds, soil characteristics,
site limitations, ability to sample the target domain, whether or not
screening procedures are to be used, the size of sample needed,
and the required precision and accuracy as given in the DQOs.
The number of samples to be collected can greatly affect sam-
pling costs and the time required to complete a site characteriza-
tion. If many subsurface samples are needed, it may be possible
to use soil-gas sampling coupled with on-site analysis as an
integrated screening technique to reduce the area of interest and
thus the number of samples needed. Such a sampling approach
may be applicable for cases of near-surface contamination.
Ultimately, the sampling, sample handling, containerizing, and
transport of the soil sample should minimize losses of volatiles
and should avoid contamination of the sample. Soil sampling
equipment should be readily decontaminated in the field if it is to
be reused on the job site. Decontamination of sampling equip-
ment may require the use of decontamination pads that have
impervious liners, wash and rinse troughs, and careful handling
of large equipment. Whenever possible, a liner should be used
inside the sampling device to reduce potential cross contamina-
tion and carryover. Decontamination procedures take time,
require extra equipment, and ultimately increase site character-
ization costs. Ease and cost of decontamination are thus impor-
tant factors to be considered in device selection.
Several soit-screening procedures are in use that include
headspace analysis of soils using organic vapor analyzers: water
(or NaCI-saturated water) extraction of soil, followed by static
headspace analysis using an organic vapor analyzer (OVA) or
gas chromatograph (GC);colorimetrictest kits; methanol extrac-
tion followed by headspace analysis or direct injection into a GC;
and soil-gas sampling (U.S. EPA, 1988). Field measurements
may not provide absolute values but often may be a superior
means of obtaining relative values. These procedures are gain-
ing acceptance.
Site Characteristics
The remoteness of a site and the physical setting may restrict
access and, therefore, affect equipment selection. Such factors
as vegetation, steep slopes, rugged or rocky terrain, overhead
power lines or other overhead restrictions, and lack of roads can
contribute to access problems.
The presence of underground utilities, pipes, electrical lines,
tanks and leach fields can also affect selection of sampling
9
-------
equipment. If the location or absence of these hazards cannot
be established, it is desirable to conduct a nonintrusive survey
of the area and select a sampling approach that minimizes
hazards. For example, hand tools and a backhoe are more
practical under such circumstances than a large, hollow-stem
auger. The selection of a sampling device may be influenced by
other contaminants of interest such as pesticides, metals,
semivolatile organic compounds, radionuclides, and explo-
sives. Where the site history indicates that the matrix is other
than soil, special consideration should be given to device
selection. Concrete, reinforcement bars, scrap metal, and lum-
ber will affect sampling device selection. Under some circum-
stances, it may not be practical to collect deep soil samples. The
presence of ordnance, drums, concrete, voids, pyrophoric ma-
terials, and high-hazard radioactive materials may preclude
some sampling and may require development of alternate
sampling designs, or even reconsideration of project objectives.
Soil Characteristics
The characteristics of the soil material being sampled have a
marked1 effect upon the selection of a sampling device. An
investigator must evaluate soil characteristics, the type of VOC,
and the depth at which a sample is to be collected before
selection of a proper sampling device. Specific charactenstics
that must be considered are:
1. Is the soil compacted, rocky, or rubble filled? If the answer
is yes, then either hollow stem augers or pit sampling must
be used.
2. Is the soil fine grained? If yes, use split spoons, Shelby
tubes, liners, or hollow stem augers.
3. Are there flowing sands or water saturated soils7 If yes, use
samplers such as piston samplers that can retain these
materials.
SOIL-GAS MEASUREMENTS
Soil-gas measurements can serve a variety of screening pur-
poses in soil sampling and analysis programs, from initial site
reconnaissance to remedial monitoring efforts. Soil-gas mea-
surements should be used for screening purposes only, and not
for definitive determination of soil-bound VOCs. Field analysis
is usually by hand-held detectors, portable GC or GC/MS,
infrared detectors, ion mobility spectrometers (IMS), industrial
hygiene detector tubes, and, recently, fiber optic sensors.
At some sites, soil-gas sampling may be the only means of
acquiring data on the presence or absence of VOCs in the soil.
For example, when the size and density of rocks and cobbles
at a site prevent insertion and withdrawal of the conng device
and prevent sampling with shovels and trowels, unacceptable
losses of VOCs would occur. Soil-gas measurements, which
can be made on site or with collected soil samples, can be used
to identify volatile contaminants and to determine relative
magnitudes of concentration. Smith et al. (1990) have shown
a disparity in soil-gas VOC concentrations and the concentra-
tion of VOCs found on the solid phase.
Soil-gas measurements have several applications. These in-
clude in situ soil-gas surveying, measurement of headspace
concentrations above containerized soil samples, and scan-
ning of soil contained in cores collected from different depths.
These applications are summarized in Table 6. Currently, no
TABLE 6. APPLICATIONS OF SOIL-GAS MEASUREMENT TECHNIQUES IN SOIL SAMPLING FOR VOCs
Application
Uses
Methods
Benefits/limitations
Soil vapor Identify sources and extent
surveying of contamination. Distinguish
between soil and ground water
contamination. Detect VOCs
under asphalt, concrete, etc.
Active sampling from soil probes
into canisters, glass bulbs, gas
sampling bags. Passive sampling
onto buried adsorptive substrates.
Followed by GC or other analysis.
BENEFITS: Rapid, inexpensive screening of
large areas, avoid sampling uncontaminated areas.
LIMITATIONS: False positives and negatives, miss
detecting localized surface spills, disequilibrium
between adsorbed and vapor phase VOC
concentrations.
Soil headspace Screen large numbers of soil
measurements samples.
Measure headspace above
containenzed soil sample.
Containers range from plastic
sandwich bags to VOA vials.
Use GC, vapor detectors, IMS, etc.
BENEFITS: More representative of adsorbed solid
phase concentration.
LIMITATIONS: Losses of vapor phase component
during sampling and sample transfer.
Screening Soil cores scanned to locate
soil cores depth where highest VOC
levels are located.
Collect core sample (e.g., unlined
split spoon) and scan for vapors near
core surface using portable vapor
monitor.
BENEFITS: Locate and collect soil from hot spot
in core for worst case.
LIMITATIONS: False negatives and positives,
environmental conditions can influence readings
(e.g., wind speed and direction, temperature, humidity).
10
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standard protocols exist for soil-gas analysis; many investiga-
tors have devised their own techniques, which have varying
degrees of efficacy Independently, the American Society for
Testing and Materials (ASTM) and EPA EMSL-LV are preparing
guidance documents for soil-gas measurement. These docu-
ments should be available late in 1991.
The required precision and accuracy of site characterization, as
defined in the DQOs, affect the selection of a sampling device.
Where maximum precision and accuracy are required, sampling
devices that collect an intact core should be used, particularly for
more volatile VOCs in nonretentive matrices. Augers and other
devices that collect highly disturbed samples and expose the
samples to the atmosphere can be used if lower precision and
accuracy can be tolerated. Collection of a larger number of
samples to characterize a given area, however, can compen-
sate for a less precise sampling approach. The closer the
expected contaminant level is to the action or detection limit, the
more efficient the sampling device should be for obtaining an
accurate measurement.
SOIL SAMPLING DEVICES
Table 7 lists selection criteria for different types of commercially
available soil sampling devices based on soil type, moisture
status, and power requirements. The sampling device needed
to achieve a certain sampling and analysis goal can be located
in Table 7 and the supplier of such a device can be identified in
Table 8. Table 8 is a partial list of commercially available soil
sampling devices that are currently in use for sampling soils for
VOC analysis. The list is by no means exhaustive and inclusion
(Continued on page 14)
TABLE 7. CRITERIA FOR SELECTING SOIL SAMPLING EQUIPMENTf
Obtains
Most
Operation
Suitable Soil
Relative
Labor
Manual
Core
Suitable
in Stony
Moisture
Sample
Requirements
or Power
Type of Sampler
Samples
Soil types
Soils
Conditions
Size
(# of Persons)
Operation
A. Mechanical Sample Recovery
1. Hand-held Power augers
No
Coh/coh'less
Unfavorable
Intermediate
Large
2+
Power
2. Solid stem flight augers
No
Coh/coh'less
Favorable
Wet to dry
Large
2+
Power
3. Hollow-stem augers
Yes
Coh/coh'less
Fav/unfav
Wet to dry
Large
2+
Power
4. Bucket augers
No
Coh/coh'less
Favorable
Wet to dry
Large
2+
Power
5. Backhoes
No
Coh/coh'less
Favorable
Wet to dry
Large
2+
Power
B. Samplers
1. Screw-type augers
No
Coh
Unfavorable
Intermediate
Small
Single
Manual
2. Barrel augers
a. Post-hole augers
No
Coh
Unfavorable
Wet
Large
Single
Manual
b. Dutch augers
No
Coh
Unfavorable
Wet
Large
Single
Manual
c. Regular barrel augers
No
Coh
Unfavorable
Intermediate
Large
Single
Manual
d. Sand augers
No
Cohless
Unfavorable
Intermediate
Large
Single
Manual
e. Mud augers
No
Coh
Unfavorable
Wet
Large
Single
Manual
3. Tube-type samplers
a. Soil samplers
Yes
Coh
Unfavorable
Wet to dry
Small
Single
Manual
b. Veihmeyer tubes
Yes
Coh
Unfavorable
Intermediate
Large
Single
Manual
c. Shelby tubes
Yes
Coh
Unfavorable
Intermediate
Large
2+'
Both
d. Ring-lined samplers
Yes
Coh'less
Favorable
Wet to intermediate
Large
2+'
Both
e. Continuous samplers
Yes
Coh
Unfavorable
Wet to dry
Large
2+
Power
f. Piston samplers
Yes
Coh
Unfavorable
Wet
Large
2+*
Both
g. Zero-contamination samplers Yes
Coh
Unfavorable
Wet to intermediate
Small
2+*
Both
h. Split spoon samplers
Yes
Coh
Unfavorable
Intermediate
Large
2+*
Both
4. Bulk samplers
No
Coh
Favorable
Wet to dry
Large
Single
Manual
t Adapted from U.S. EPA, 1986a.
" All hand-operated versions of samplers, except for continuous samplers, can be worked by one person.
Coh = cohesive.
11
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TABLE 8. EXAMPLES OF COMMERCIALLY AVAILABLE SOIL SAMPUNG DEVICES
Manufacturers
Sampling Device
-Specifications-
Length (inches)
I.D. (Inches)
Sampler Material
Liners
Features
Associated Design &
Manufacturing Co.
814 North Henry Street
Alexandria, VA 22314
703-549-5999
Purge and Trap
Soil Sampler
3
0.5
Stainless steel
Will rapidly sample soils
for screening by "Low Level"
Purge and Trap methods.
Acker Drill Co.
P.O. Box 830
Scranton, PA
717-586-2061
Heavy Duty "Lynac"
Split Tube Sampler
Dennison Core Barrel
18 & 24
1-1/2 to 4-1/2
Steel
24 & 60
1-7/8 to 6-5/16
Brass,
stainless
Brass
Split tube allows for easy
sample removal.
Will remove undisturbed
sample from cohesive soils.
AMS
Harrison at Oregon Trail
American Falls, ID 83211
Core Soil Sampler.
Dual Purpose Soil
Recovery Probe
Soil Recovery Auger
2 to 12
1-1/2 to 3
Alloy, stainless
12,18&24
3/4 and 1
4130 Alloy,
stainless
8 to 12
2 & 3
Stainless
Stainless, plastic
aluminum, bronze
teflon
Butyrate, Teflon
stainless
Plastic, stainless
Teflon, aluminum
Good in all types of soils.
Adapts to AMS 'up & down'
hammer attachment. Use
with or without liners.
Adaptable to AMS extension
and cross-handles.
Concord, Inc.
2800 7th Ave. N.
Fargo, ND 58102
701-280-1260
Speedy Soil Sampler
Zero Contamination Unit
Hand-Held Sampler
48 & 72
3/16 to 3-1/2
Stainless
Acetate
Automated system allows
retrieval of 24 in soil
sample in 12 sec.
CME
Central Mine Equip. Co.
6200 North Broadway
St. Louis, WO 63147
800-325-8827
Continuous Sampler
60
2-1/2 to 5-3/8
Steel, stainless
Bearing Head Continuous 60
Sample T ube System 2-1/2
Steel, stainless
Butyrate
Butyrate
May not be suitable in
stony soils. Adapts to CMS
auger.
Versatile system. Adapts
to all brands of augers.
Diedrich Drilling Equip.
P.O. Box 1670
Laporte, IN 46350
800-348-8809
Heavy Duty Split
Tube Sampler
Continuous Sampler
18 & 24
2.2-1/2,3
Steel
60
3.3-1/2
Brass, plastic
stainless,Teflon
Brass, plastic
stainless, Teflon
Full line of accessories
are available.
Switch-out device easily
done.
12
(Continued)
-------
TABLE 8. (CONTINUED)
Manufactures
Sampling Device
Specifications
Length (inches)
I.D. (inches)
Sampler Material
Liners
Features
Geoprobe Systems
607 Barney St.
Salina, KS
913-825-1842
Probe Dnve
Soil Sampler
11-1/4
0.96
Alloy steel
Remains completely sealed
while pushed to depth in
soil.
Giddings Machine Co.
P.O. Drawer 2024
Fort Collins, CO 80522
303-485-5586
Coring Tubes
48 & 60
7/8 to 2-3/8
4130 Molychrome
Butyrate
A series of optional 5/8 in
slots permit observation of
the sample.
JMC
Clements and Associates
R.R. 1 Box 186
Newton, IA 50208
800-247-6630
Environmentalist's
Sub-soil Probe
Zero Contamination
36 & 48
0.9
Nickel plated
12,18 & 24
PETG plastic,
stainless
PETG plastic,
Adapts to drop-hammer to
penetrate the hardest of soils.
Adapts to power probe.
Tubes 0.9 stainless
Nickel plated
Mobile Drilling Co. "Lynac" Split 18 & 24 Brass, Adapts to Mobile wireline
3807 Madison Ave. Barrel Sampler 1-1/2 plastic sampling system.
Indianapolis, IN 46227
800-428-4475
Solitest, Inc.
66 Albrecht Drive
Lake Bluff, IL
800-323-1242
Zero Contamination
Sampler
Thin Wall Tube
Sampler (Shelby)
Split Tube Sampler
Veihmeyer Soil
Sampling Tube
12,18 & 24
0.9
Chrome plated
30
2-1/2,3,3-1/2
Steel
24
1-1/2 to 3
Steel
48 & 72
3/4
Steel
Stainless,
acetate
Brass
Hand sampler good for
chemical residue studies.
Will take undisturbed samples
in cohesive soils and days.
Forced into soil by jacking,
hydraulic pressure or driving.
Very popular type of sampler.
Adapts to drop hammer for
sampling in all sorts of soils.
Sprague & Henwood, Inc. S & H Split Barrel 18&24
Scranton, PA 18501 Sampler 2 to 3-1/2
800-344-8506
Brass,
plastic
A general ail-purpose
sampling device designed
for driving into material to
be sampled.
Note: This list is not exhaustive. Inclusion in this list should not be construed as endorsement for use.
13
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in the list should not be construed as an endorsement for their
use.
Commonly, soil samples are obtained from the near surface
using shovels, scoops, trowels, and spatulas. These devices
can be used to extract soil samples from trenches and pits
excavated by back hoes. A precleaned shovel or scoop can be
used to expose fresh soil from the face of the test pit. A thin-
walled tube or small-diameter, hand-held corer can be used to
collect soil from the exposed face. Bulk samplers such as
shovels and trowels cause considerable disturbance of the soil
and expose the sample to the atmosphere, enhancing loss of
VOCs. Siegrist and Jenssen (1990) have shown that sampling
procedures that cause the least amount of disturbance provide
the greatest VOC recovenes. Therefore, sampling devices that
obtain undisturbed soil samples using either hand-held or me-
chanical devices are recommended. Sampling devices that
collect undisturt>ed samples include split-spoon samplers, ring
samplers, continuous samplers, zero-contamination samplers,
and Shelby tubes. These sampling devices can be used to
collect surface soil samples or they can be used in conjunction
with hollow-stem augers to collect subsurface samples. The soil
sampling devices discussed above are summarized in Table 9.
Devices where the soil samples can be easily and quickly
removed and containerized with the least amount of disturbance
and exposure to the atmosphere are highly recommended. U.S.
EPA (1986a) gives a more detailed discussion on the proper use
of drill rigs and sampling devices.
Liners are available for many of the devices listed in Table 9.
Liners make soil removal from the coring device much easier
and quicker. Liners reduce cross contamination between
samples and the need for decontamination of the sampling
device. The liner can run the entire length of the core or can be
precut into sections of desired length.
When sampling for VOCs, it is critical to avoid interactions
between the sample and the liner and between the sample and
the sampler. Such interactions may include either adsorption of
VOCs from the sample or release of VOCs to the sample.
Gillman and O'Hannesin (1990) studied the sorption of six
monoaromatic hydrocarbons in ground water samples by seven
materials. The hydrocarbons included benzene, toluene,
ethylbenzene, and o-t m-, and p-xylene. The materials exam-
ined were stainless steel, rigid PVC, flexible PVC, PTFE Teflon,
polyvinylidene fluoride, fiberglass, and polyethylene. Stainless
TABLE 9. SOIL SAMPLERS FOR VOC ANALYSIS
Recommended
Not Recommended
Split spoon w/liners
Solid flight liners
Shelby tube (thin wall tubes)
Drilling mud auger
Hollow-stem augers
Air drilling auger
Veihmeyer or King tubes
Cable tool
w/liners
Hand augers
Piston samplers*
Barrel augers
Zero contamination samplers'
Scoop samplers
Probe-drive samplers
Excavating tools, e.g., shovels, backhoes
May sustain VOC losses if not used with care
steel showed no significant sorption during an 8-week period. All
polymer materials sorbed all compounds to some extent. The
order of sorption was as follows: rigid PVC < fiberglass <
polyvinylidene fluoride < PTFE < polyethylene < flexible PVC.
Stainless steel or brass liners should be used since they exhibit
the least adsorption of VOCs. Other materials such as PVC or
acetate may be used, provided that contact time between the
soil and the liner material is kept to a minimum. Stainless steel
and brass liners have been sealed with plastic caps or paraffin
before shipment to the laboratory for sectioning and analysis.
VOC loss can result from permeation through the plastic or
paraffin and volatilization through leaks in the seal. Acetate
liners are available, but samples should not be held in these
liners for any extended period, due to adsorption onto and
permeation through the material. Alternatively, the soil can be
extruded from the liner, and a portion can be placed into a wide-
mouth glass jar. Smaller aliquots can be taken from the center
of the precut liner using subcoring devices and the soil plug
extruded into VOA vials.
TRANSFER OF SOIL SAMPLES FROM DEVICE TO
CONTAINER
The sample transfer step is perhaps the most critical and least
understood step in the sampling and analysis procedure. The
key point in sample transfer, whether in the field or in the
laboratory, is to minimize disturbance and the amount of time the
sample is exposed to the atmosphere. It is more important to
transfer the sample rapidly to the container than to accurately
weigh the aliquot which is transferred, or to spend considerable
time reducing headspace. Therefore, a combination of a device
for obtaining the appropriate mass of sample and placement of
the aliquot into a container that can be directly connected to the
analytical device in the laboratory is recommended. Several
designs are available for obtaining a 5-g aliquot (or other size).
Most subconng devices consist of a plunger/barrel design with
an open end. The device shown in Figure 3 was constructed by
Associated Design & Manufacturing Company (Alexandria,
VA). Other designs include syringes with the tips removed, and
cork borers (Table 8). The device is inserted into the sample and
an aliquot is withdrawn. The aliquot, which is of a known volume
and approximate weight, can then be extruded into a tared 40-
mL VOA vial. Routinely, the vial is then sealed with a Teflon-lined
septum cap. Teflon, however, may be permeable to VOCs.
Aluminum-lined caps are available to reduce losses due to
permeation. At the laboratory, the vial must be opened and the
contents of the vial must be transferred to a sparger tube. The
transfer procedure will result in significant losses of VOCs from
the headspace in the vial. The modified purge-and-trap cap
shown in Figure 4 eliminates the loss of VOCs due to container
opening and sample transfer. The soil is extruded from the
subcorer into a tared 40-mL VOA vial and the modified cap is
attached in the field. In the laboratory, the vial is attached directly
to a purge-and-trap device without ever being opened to the
ambient air.
Use of subcoring devices should produce analytical results of
increased accuracy. In order to test this hypothesis, an experi-
ment was conducted in which a bulk soil sample was spiked with
800 ng/kg of different VOCs (Maskarinec, 1990). Three aliquots
were withdrawn by scooping, and three aliquots were withdrawn
by using the sub-corer approach. The results are presented in
Table 10. Although neither method produced quantitative recov-
ery , the subcorer approach produced results that were generally
14
-------
Figure 3. Small-diameter hand-held subcoring device made
by Associated Design & Manufacturing Company
(Alexandria, VA).
TABLE 10. LABORATORY COMPARISON OF STANDARD METHOD
AND SUBCORER METHOD
Standard
Method
Subcorer
%of
%of
Standard
Subcorer
Recovery
Recovery
Compound
Method*
Method"
of Spike
of Spike
Chloromethane
50
1225
6
153
Bromomethane
31
536
4
67
Chloroethane
78
946
10
118
1,1 -Dichloroethene
82
655
10
82
1,1 -Dichloroethane
171
739
21
92
Chloroform
158
534
20
67
Carbon tetrachloride
125
658
16
82
1,2-Dichloropropane
147
766
18
96
Trichloroethene
120
512
15
64
Benzene
170
636
21
80
1,1,2-Trichloroethane
78
477
10
60
Bromoform
30
170
4
21
1,1,2,2-Trichloroethane
46
271
6
34
Toluene
129
656
16
82
Chlorobenzene
57
298
7
37
Ethylbenzene
68
332
8
42
Styrene
30
191
4
24
^9 (1=3)
pg/vg (n=3)
Note: Standard method of sample transfer consists of scooping and subconer
method uses device shown in Figure 3. Soil samples were spiked with 800
pg/Vg of each VOC.
five times higher than the standard approach, whereby the
contents of a 125-mL wide-mouth jar are poured into an alumi-
num tray and homogenized with a stainless steel spatula. A 5-
g sample is then placed in the sparger tube (SW-846, Method
8240). Several compounds presented problems with both
approaches: styrene polymerizes, bromoform purges poorly,
and 1,1,2,2-tetrachloroethane degrades quickly.
1/2" Stainless
Steel Body
O-RIng
1/16"
Teflon Ball
Receiving union from
Purge-and-Trap Device
1/2" Stainless
Steel Body
O-Ring
Hole Cap
40 mL Vial
Purge Needle
Figure 4. Modified purge-and-trap 40-mL VOA vial cap for
containerizing samples in the field. Vial is
attached directly to a purge-and-trap system
without exposure of sample to the atmosphere.
15
-------
In another study (U S. EPA, 1991 a), a large quantity of well
characterized soil was spiked with 33 VOCs and was homog-
enized. From the homogenized material, a 5-g aliquot of soil was
placed in a 40-mL VOA vial and sealed with a modified purge-
and-trap cap (Figure 4). The remaining soil was placed in 125-
mL wide-mouth jars. The samples were shipped via air carrier
and were analyzed by GC/MS with heated purge and trap. The
40-mL VOA vials were connected directly to a Tekmar purge-
and-trap unit without exposure to the atmosphere. The wide-
mouth jars were processed as per SW-846 Method 8240 speci-
fications (U.S. EPA, 1986b). Table 11 compares the results of
the GC/MS analyses using the two pretreatment techniques.
The modified method (40-mL VOA vial with a modified cap)
yielded consistently higher VOC concentrations than the tradi-
tional Method 8240 procedure (U.S. EPA, 1986b).
The standard methods for VOC analysis, SW-846, Method 8240
and Test Method 624 (U.S. EPA, 1986b; U.S. EPA, 1982), call
for the containerizing of soil samples in 40-mL VOA vials or 125-
mL wide-mouth jars with minimal headspace. As previously
described, wide-mouth jars may not be the most appropriate
containers due to sample aliquoting requirements. Although
wide-mouth jars may be equally as effective as 40-mL VOA vials
in maintaining the VOC content of soil samples, the sample
preparation procedure that is required with jar-held samples
causes significant (>80%) loss of highly volatile VOCs (Siegrist
and Jennsen, 1990). However, if samples are collected in such
containers, it is important to ensure sample integrity, preferably
by using amber glass jars (for photosensitive compounds) with
solid phenolic resin caps and foam-backed Teflon liners. Alumi-
num-lined caps are not available for the wide-mouth jars. Soil
should be wiped from the threads of the jar to ensure a tight seal.
The methanol-immersion procedure calls for the transfer of the
sample into a glass jar containing a known volume of chromato-
graphic-grade methanol (usually 100 mL) or in a 1:1 weight-to-
volume ratio of soil to methanol. This has the effect of preserving
the volatile components of the sample at the time the sample is
placed in the container. Furthermore, surrogate compounds can
be added at this time in order to identify possible changes in the
sample dunng transport and storage. The addition of methanol
to the sample raises the detection limits from 5 to 10 ng/kg to 100
to 500 iig/kg, because of the attendant dilution. However, the
resulting data have been shown to be more representative of the
original VOC content of the soil (Siegrist and Jennsen, 1990;
Siegrist, 1990). In a comparison of transfer techniques, Siegrist
and Jennsen (1990) demonstrated that minimum losses were
obtained by using an undisturbed sample followed by immediate
TABLE 11. COMPARISON OF VOC CONCENTRATIONS IN SPIKED SOIL ANALYZED BY METHOD 8240 AND MODIFIED METHOD 8240
VOC
Concentration (pfl/kg)
Modified
Method Method
8240f 8240ft Difference VOC
Concentration (ng/kg)
Modified
Method Method
8240f 8240ft Difference
Bromo methane
9
44
35"
Dibromochloromethane
121
159
38
Vinyl chloride
3
32
29"
1,1,2-Trichloroethane
142
193
51
Chtoroethane
6
36
30"
trans-1,3-Dichloropropene
154
203
49
Methylene chloride
69
100
31"
Bromoform
116
140
24
Carbon disulfide
32
82
50"
Tetrachloroethene
62
124
62*
1,1-Dichloroethene
12
35
23"
1,1,2,2-Tetrachloroethane
137
162
25
1,1 -Dichloroethane
34
83
49"
Toluene
85
161
76'
1,2-Dichloroethene
36
66
30"
Chlorobenzene
91
132
41*
Chloroform
56
96
40"
Ethylbenzene
85
135
50'
1,1,1-Trichloroettiane
26
80
54"
Styrene
86
114
28*
Carbon tetrachlonde
18
61
43"
Total xylenes
57
85
28'
Vinyl acetate
18
26
8
1,2-Dichioroettiane
101
159
58"
KETONES
cis-1,3-Oichloropropene
136
189
53*
Acetone
336
497
16V
Trichloroethene
48
87
39"
2-Butanone
290
365
75
Benzene
56
114
58'
2-Hexanone
200
215
15
Bromodichlorometfiane
111
166
55*
4-Methly-2-pentanone
264
288
24
t Method 8240 using 125-mL wide-mouth jar moang subsampf ng in laboratory purge/trap analysis,
ft Method 8240 using 40-mL vial. 5-g sampled in the field, shipped to laboratory purge/trap analysis.
" Difference significantly greater than 0, with P-value <0.01.
' Difference significantly greater than 0, with P-value between 0.01 and 0.05.
Note: Spike concentration was 300 pQ/kg.
16
-------
immersion into methanol. The results for six VOCs are shown in
Figure 5. At high VOC spike levels (mg/kg) the investigators
found that headspace within the bottle caused a decrease in the
concentration of VOCs in the sample. At lower spike levels,
however, headspace did not seem to be a major contributor to
VOC losses (Maskarinec, 1990). In another study (U.S. EPA,
1991 a), it was found that a 5-g sample collected from a soil core
and placed in a 40-mL VOA vial provided consistently higher
concentration, ppm
20
15
TREATMENT A
UNDISTURBED SOIL
PLASTIC BAG
LOW HEADSPACE
TREATMENTB
UNDISTURBED SOIL
GLASS JAR
HIGH HEADSPACE
TREATMENTC
DISTURBED SOIL
GLASS JAR
LOW HEADSPACE
TREATMENT 0
UNDISTURBED SOIL
GLASS JAR
LOW HEADSPACE
TREATMENTE
UNDISTURBED SOIL
GLASS JAR
METHANOL
10
TREATMENT A
TREATMENT B
TREATMENT C
TREATMENTD
TREATMENTE
METHYLENE CHLORIDE
1,2-DICHLOROETHANE
concentration, ppm
TREATMENT A TREATMENT B TREATMENT C TREATMENT D TREATMENT E
VZ1 1,1,1 ,-TRICHLOROETHANE
^ TOLUENE
TRICHLOROETHENE
CHLOROBENZENE
Figure 5. VOC recovery as a function of sample treatment.
17
-------
VOC leveJs than a sample taken from the same core, placed in
a 125-mL wide-mouth jar, and later poured out. homogenized,
and a 5-g aliquot taken from the bulk material as per Method
8240 specifications.
SOIL SAMPLING SCENARIOS
The following recommendations for soil sampling and sample
handling are presented for the three general sampling sce-
narios described earlier.
1. Open Test Pit or Trench
Samples are often collected from exposed test pits or trenches
where remediation efforts are in progress. Sites may also be
encountered where large-diameter coring devices cannot be
employed. In such instances, crude sampling devices, such as
trowels, spoons, shovels, spades, scoops, hand augers, or
bucket augers must be used to excavate the soil.
The exposed face of an excavated test pit is scraped to uncover
fresh material. Samples are collected from the scraped face by
using a small-diameter, hand-held corer (Figure 3). If the
nominal 5-g sample is to be collected, the appropriate volume
(3 to 4 mL) is extruded into a tared 40-mL VOA vial and sealed
with a modified purge-and-trap cap (Figure 4). The vial is chilled
to 0° to 4°C and sent to the laboratory where the entire contents
of the vial are purged without opening the vial (U.S. EPA
1991b). Though this method minimizes losses of VOCs, the
small sample size may exhibit greater short-range spatial
variability than larger samples.
Alternatively, a small-diameter, hand-held soil corer (Figure 3)
can be used to collect a larger volume of soil. The soil is
extruded to fill a 40-mL VOA vial with a Teflon-lined septum cap
(minimal headspace), chilled, and sent to the laboratory. The
major weakness with this method is that VOCs are lost in the
laboratory during sample homogenization, preparation of
aliquots from a subsample, and the transfer to the extraction or
sparging device.
If large coarse fragments or highly compacted soils are encoun-
tered, the use of a hand-held corer may not be possible. In this
case crude sampling devices are used to rapidly collect and fill
(minimal headspace) a 125- or 250-mL wide-mouth glass jar.
The threads are wiped clean and the jar is sealed with a foam-
backed Teflon-lined cap. The jar is chilled immediately to 0° to
4°C for' shipment to the laboratory. Losses of VOCs are consid-
erably greater with this method due to disruption of the matrix
and losses in the laboratory during sample preparation. Metha-
nol immersion may be more suitable for these matrices.
2. Surface Soils (< 5 ft deep)
The preferred soil sampling procedures reduce VOC losses by
minimizing sample disturbance during collection and transfer to
a container. The collection of soil cores with direct extrusion into
a container accomplishes this goal. A larger-diameter coring
device (e.g., split-spoon sampler, Shelby tube, zero-contami-
nation sampler) is used to collect an intact sample from the
surface soil or from an augered hole. Many of these samplers
can be used with liners, an insert that greatly reduces the time
required to remove the soil and obtain a subsample. For
subsamples collected from split spoons or extruded large-
diameter cores, the section to be subsampled is scraped and
laterally subcored, or the extruded soil is cut or broken to expose
fresh material at the depth or zone of interest, then longitudinally
subcored. For large-diameter cores that are collected in precut
liners, the liner sections are separated with a stainless steel
spatula, and a small-diameter hand-held corer is used to collect
a subsample from the center of the liner section. The uppermost
portion of the core should not be sampled, because it is more
likely to be cross contaminated. The small diameter corer
(Figure 3) is pushed into the soil, the outside of the corer is wiped
clean, and the required core volume (typically about 3 to 4 mL
or 5 g) is extruded directly into a tared 40-mL glass VOA vial and
sealed with a modified purge-and-trap cap (Figure 4). The vial
threads and lip must be free of soil to ensure an airtight seal.
3. Subsurface soils (> 5 ft deep)
The same sampling principles apply for the collection of deeper
soil samples. Collection of soil cores with direct extrusion into a
container greatly reduces the loss of VOCs. Tube-type samplers
such as split-spoon, Shelby tubes, and zero-contamination
samplers are used inside a hollow-stem auger to obtain an intact
sample from greater depths. The coring device is retrieved and
a subsample is obtained in a similar manner as that described
for surface soils.
METHANOL IMMERSION PROCEDURE
Soil collected by protocols outlined above can be placed in a
tared wide-mouth glass jar containing pesticide-grade methanol
(1:1 weight-to-volume ratio of soil to methanol). The immersion
of relatively large soil samples into methanol has the advantage
of extracting a much larger sample that is probably less prone to
short-range spatial variability. This is of particular advantage
with coarse-grained soils, materials from which it is hard to
obtain a 1-g to 5-g subsample for analysis.
Multiple small-diameter corers can be immersed in a single
methanol-filled jar to produce a composite sample.
Compositing becomes practical because VOCs are soluble in
methanol, thus reducing losses. Appropnately collected com-
posite samples can produce more representative data than a
comparable number of individual samples. Short-range spatial
variability is greatly reduced. Another advantage is the ability to
reanalyze samples. The main disadvantages of using methanol
include the requirements for handling and shipping the metha-
nol and the detection limit that is raised by a factor of about 10
to 20. For the methanol-immersion procedure, jars filled with
methanol and shipped to the laboratory are classified as a
hazardous material, flammable liquid and must be labelled as
per Department of Transportation specifications (49 CFR,
1982). If these disadvantages are unacceptable, then the
modified purge-and-trap procedure may be applicable.
FIELD STORAGE
Material containing VOCs should be kept away from the sample
and the sample container. Hand lotion, labeling tape, adhesives,
and ink from waterproof pens contain VOCs that are often
analytes of interest in the sample. Samples and storage contain-
ers should be kept away from vehicle and generator exhaust and
other sources of VOCs. Any source of VOCs may cause
contamination that may compromise the resulting data.
18
-------
Once samples are removed from the sampling device and
placed in the appropriate storage container, the containers
should be placed in the dark at reduced temperatures (0° to
4°C). Excessively cold temperatures (<-10oC) should be
avoided; studies have shown greater losses of analytes due to
reduced pressures in the container, sublimation of water, and
concomitant release of water-soluble VOCs into the headspace.
Upon opening the container, the vacuum is quickly replaced with
ambient air, thus purging out VOCs from the headspace
(Maskarinec et al., 1988). Extremely cold temperatures can also
loosen the seal on the container cap. Caps should be
retightened after 15 minutes at reduced temperatures. Samples
should be kept in ice chests while in route to the shipment facility
or laboratory. At temperatures above freezing, bacterial action
can have a significant impact on the observed soil VOC con-
centration. Numerous preservation techniques are being
evaluated at the University of Nevada Environmental Research
Center in Las Vegas and at Oak Ridge National Laboratory.
15 ¦
14 •
13'
12-
11 '
10'
AIRBORNE
pressure
TEMPERATURE
0
-5 0 5 19 15 202S 30 35 4045
SHIPPING
Given the short holding times required for VOC analysis under
Method 8240 (10 days from sample collection to analysis),
samples are usually shipped via air carrier to the analytical
laboratory. Samples should be well packed and padded to
prevent breakage. Temperatures in cargo holds can increase to
more than 50°C during transit, therefore, the need for adequate
cold storage is critical. Styrofoam coolers are commercially
available to accommodate 40-mL and 125-mL glass containers.
SufficientquantitiesofBlue Ice™ or Freeze-Gel™ packs should
be placed in the container to ensure that samples are cooled for
the duration of the shipment. A maximum-minimum thermom-
eter (non-mercury) should be shipped with the samples. If
sample containers are not adequately sealed, VOC losses can
occur. These losses may be exacerbated by the reduced
atmospheric pressures encountered in the cargo holds of air
carriers. Figure 6 illustrates the changes in temperature and
pressure in the cargo hold of various air carrier's aircraft. Three
major air carriers have been monitored and have shown similar
fluctuations in temperature and pressure (Lewis and Parolini,
1991). Lewis et al. (1990) noted decreases in VOC concentra-
tions in soil samples that were shipped compared to samples
that were analyzed in the field. If the container is of questionable
or unknown integrity, it should either be evaluated prior to use or
a previously characterized container should be used.
As discussed previously, samples that are immersed in metha-
nol have special shipping requirements. These samples must
be shipped as 'Flammable Liquids* under Department of Trans-
portation (DOT) requirements. A secondary container is re-
quired for shipment of any item classified as a flammable liquid.
PRESERVATION
Improvements in operational factors such as sampling device
efficiency, sample transfer, containerizing, shipping, storage,
laboratory sample preparation, and analysis will reduce VOC
losses from soils. Two principal matrix-specific factors that can
contribute to the loss of VOC in soils are biodegradation and
volatilization. An effective preservation technique should act on
these matrix-specific factors to reduce losses of VOCs.
The required preservation technique for soil samples is storage
at 0° to 4°C in the dark. This technique retards biodegradation
FEDERAL EXPRESS
O
o
in
CM
w
a.
2
3
(0
(0
©
-5 D 5 10 15 20 25 30 35 40 45
UPS
TEWEM1URE
100
80
GO
40
20
•5 0 5 10 15 20 25 30 35 40 45
Elapsed Time (hr)
Figure 6. Temperature and pressure fluctuations recorded in
the cargo hold of various air carriers. Recording
device was shipped from Las Vegas, NV, to Pearl
River, NY, and returned.
19
-------
processes mediated by soil microorganisms. Some microorgan-
isms, however, such as fungi, are biologically active even at
4°C. Wolf et al. (1989) investigated several methods (i.e ,
chemical and irradiation) for sterilizing soil and concluded that
mercuric chloride is one of the most effective preservatives that
causes minimal changes to the chemical and physical proper-
ties ofthesoil. Stuart et al.(1990) utilized mercuric chloride as an
antimicrobial preservative to stabilize ground-water samples
contaminated with gasoline. Other researchers (U.S. EPA
1991 a) have used mercuric chloride to retard biodegradation of
VOCs in soil samples. The soils were spiked with 150 ^g/kg of
Target Compound List (TCL) VOCs and were preserved with 2.5
mg of mercuric chloride per 5 g of soil. The results indicated that
the amount of mercuric chloride needed to reduce biodegrada-
tion was directly related to the soil's organic carbon content. In
addition, the levels of mercuric chloride added to samples did
not interfere with sample handling or analysis. Currently, re-
search is underway to quantitate the required mercuric chlonde
concentration as a function of soil organic content.
The loss of VOCs through volatilization is reduced by optimizing
sample handling procedures. When samples require laboratory
pretreatment, severe losses of VOCs (up to 100%) have been
observed. In order to minimize volatilization losses, several
preservatives have been examined (U.S. EPA 1991 a), including
solid adsorbents, anhydrous salts, and water/methanol extrac-
tion mixtures. The most efficient preservatives for reducing
volatilization of VOCs from soils have been two solid
adsorbents, Molecular Sieve - 5A™ (aluminum silicate desic-
cant) and Florasil™ (magnesium silicate desiccant). The addi-
tion of 0.2 mg per 5 g of soil greatly increased the recovery of
VOCs from spiked samples. The mechanism is believed to
involve the displacement of water from adsorption sites on the
soil particle and binding of VOCs to these freed sites. Currently,
research is in progress with soils obtained from actual contami-
nated sites.
LABORATORY PROCEDURES
Sample Storage
Most regulatory procedures specify storage of samples for VOA
at 4°C in the dark. Sample coolers should be opened under
chain-of-custody conditions, and the temperature inside the
cooler should be verified and noted. Samples should be trans-
ferred to controlled-temperature (4°C) refrigerators until analy-
sis. In many cases, insufficient cooling is provided during
transport. In these cases, data quality may be compromised.
Sample Preparation
The two most commonly used methods that satisfy regulatory
requirements for the analysis of soil samples for VOCs are direct
purge and trap and methanol extraction. Each procedure has
benefits and limitations with respect to sample preparation prior
to VOC analysis of soils.
The modified purge-and-trap procedure has the following char-
acteristics:
• Homogenization of contents of wide-mouth jar will cause
significant VOC losses. The collection of a 5-g aliquot in the
field and placement into a tared vial sealed with a modified
purge-and-trap cap is recommended.
• Surrogate addition should be made to the soil in the field, if
possible.
• May be more susceptible to short-range spatial variability.
• Samples should be brought to ambient temperature before
purging.
• May be more suitable for low-level samples.
The methanol-immersion procedure has the following charac-
teristics:
• The key is to minimize the time samples are exposed to the
atmosphere prior to immersion into methanol.
• Mrnimum detection limits can be raised by a factor of 10 to 20.
• The best option for sample archival because VOCs are highly
soluble in methanol.
• Large-mass samples can be extracted in the field in a 1:1 ratio
and the methanol extract shipped to the laboratory for
analysis.
• Can collect composite samples.
The analytical methods that can be used for the analysis of soils
for VOCs are summarized in Table 12. An analytical method
should be selected that is compatible with the recommended
sample collection and containerizing procedure discussed ear-
lier.
CONCLUSIONS AND RECOMMENDATIONS
Current research on sampling soils for VOC analyses answers
many of the questions asked by RPMs and OSCs who conduct
site characterization and restoration.
1. There is no specific method or process that can be recom-
mended for sampling soils for VOA. A wide variety of
sampling devices are currently used for collecting soil
samples for VOA. Sampling device selection is site-specific,
and no single device can be recommended for use at all
sites. Several different samplers, which cover a broad
range of sampling conditions and circumstances, are rec-
ommended for obtaining representative samples for VOC
analysis (Table 7). Procedures may vary for different VOCs.
Experiments have shown that a procedure that collects an
undisturbed, intact sample with a device that allows direct
transfer to a sample container (e.g., split-spoon, Shelby
tube, or zero-contamination sampler) is superior to a more
disruptive procedure that uses a crude bulk sampler (e.g.,
shovel, trowel, scoop, or spade) for maintaining the integrity
of VOCs in a soil sample. Large-diameter tube-type sam-
pling devices are recommended for collection of near-
surface samples. The same types of devices can be used
in conjunction with hollow-stem augers for collecting sub-
surface samples.
2. Transfer of the sample from the sampling device to the
container is a critical step in the process. Losses of as much
as 80% have been observed during this step. The faster the
soil can be removed from the sampling device and
20
-------
TABLE 12. METHODS FOR VOC ANALYSIS OF SOIL
Method
Extraction/analysis
Sample
Size
(g)
Sample
Preparation
Procedure
Sensitivity
Data
Quality
Objective
Program
Comments
5030 / 8240
5
Purge and trap
5-10
Litigation
RCRA*
Sample transfer to
/ 8010
purge and trap is
/ 8015
critical.
/ 8020
/ 8030
18260
5380 / 8240
5-100
Methanol extraction
500-1000
Litigation
RCRA
Sensitivity loss but
/ 8010
sample transfer
/ 8015
facilitated.
/ 8020
/ 8030
/ 8260
5031 / 8240
5
Field purge
5-10
Semi-
RCRA
Sample can only be
/ 8010
quantitative
analyzed once,
/ 8015
transfer and shipping
/ 8020
facilitated.
/8030
/ 8260
3810 / 8240
10
Heat to 90°C
1000
Screening
RCRA
Can be performed
/ 8010
in water bath
for purgeable
in the field.
/ 8015
and analyze
organics
/ 8020
headspace
/ 8030
/ 8260
3820
10
Hexadecane
extraction
followed by
GC/FID
500-1000
Screening
prior to GC
or GC/MS
analysis
RCRA
FID responses vary
with type of VOC.
624
5
Purge and trap
5-10
Litigation
CLP"
Similar to method
5030/8240 in
RCRA SW-846.
• U.S. EPA, 1966b
¦ U.S. EPA, 1982
21
-------
transferred into an airtight sample container, the smaller
the VOC loss. Liners make the removal and subsampling
of soil from the collection device more efficient.
3. The best method for transferring a sample from a large-
diameter coring device (or exposed test pit) into a sample
container is by collecting the appropriate size aliquot (for
laboratory analysis) with a small-diameter, hand-heldcorer
and extruding the subsample into a 40-mL VOA vial, then
sealing the vial with a modified purge-and-trap cap. Alter-
natively, contents of the large-diameter coring device can
be sectioned and immersed in methanol.
4. Small-diameter, hand-held corers can be used for col-
lecting samples from a freshly exposed face of a trench or
test pit, or for obtaining a subsample from a large-diameter
coring device. The use of a small-diameter, hand-held
corer is recommended for obtaining subsamples from
liner-held soil. Collection of a sample of the appropriate
size for a particular analytical procedure is optimal. The
required size of aliquot can be extruded into a 40-mL VOA
vial and sealed with a modified purge-and-trap cap. The
possibility exists of compositing several small-diameter
core samples by immersing them in a single jar containing
methanol.
5. Sample containers vary in terms of air-tightness. Data are
available to indicate that there is a decrease in pressure
and an increase in temperature in the cargo holds of certain
air carriers. This is the worst possible set of conditions for
maintaining VOCs in containerized soil samples. Intact
seals on storage containers and adequate cooling is thus
cntical for maintaining VOCs in soil samples. Shipping and
holding-time studies have shown that vials and jars may be
equally suited for containing VOCs in soil samples, the
laboratory pretreatment step needed to obtain an aliquot
from ajar-held sample causes significant losses of VOCs.
Commercially available shipping packages with built-in
cooling materials (e.g., Freeze Gel Packs® or Blue Ice®)
are available. Whenever possible, an integrated sampling
approach should be employed to obtain the most represen-
tative samples possible. Soil-gas surveying coupled with
on-site soil sampling and analyses followed by the Re-
source Conservation and Recovery Act (RCRA) or CLP
laboratory analyses may provide valuable information on
the partitioning of VOCs at a site.
6. The current preservation technique for soil samples is
storage at 4°C in the dark. Biological activity may continue
at this temperature. The addition of mercuric chloride to the
soil may reduce biodegradation of VOCs. The amount of
mercuric chloride to be added, however, is a function of the
organic carbon content in the soil. The most promising
preservatives for reducing losses of VOCs through volatil-
ization are solid adsorbents such as Molecular Sieve - 5A™
and Florasil™.
22
-------
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A. Gholson. 1987. Soil Gas Screening for Detection and Map-
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Hanisch, R.C. andM. A. McDevitt. 1984. Protocols for Sampling
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Lewis, T. E., B. A. Deason, C. L. Gerlach, and D. W. Bottrell.
1990. Performance evaluation materials for the analysis of
volatile organic compounds in soil: A preliminary assessment. J.
Env. Sci. Health A25(5):505-531.
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Lotse, E. G., D. A. Graetz, G. Chesters, G. B. Lee, and L. W.
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Maskarinec M. P., 1990 Personal Communication.
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May 25-26, 1988.
23
-------
McCoy, D. E. 1985. "301" studies provide insight into future of
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Plumb, R. H., Jr 1987. A practical alternative to the RCRA
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150.
Plumb, R. H., Jr., and A. M. Pitchford. 1985. Volatile organic
scans: Implications for ground water monitoring. Paper pre-
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Organic Chemicals in Ground Water, Houston, TX, November
13-15, 1985.
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Soil Sci. Soc. Am. Proc. 35:884-887.
Roy, W. R. and R. A. Griffin. 1985. Mobility of organic solvents
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Volatilization of organic chemicals from soil as related to their
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for the Assessment of Errors in the Sampling of Soils, EPA/600/
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York, NY (2nd Edition).
Vogel, T. M. and P. L McCarty. 1985. Biotransformation of
tetrachloroethylene to trichloroethylene, dichloroethylene, vinyl
chloride, and carbon dioxide under methanogenic conditions.
Appl. Environ. Microbiol. 49:1080-1084.
Voice, T. C. and W. J. Weber, Jr. 1983. Sorption of hydrophobic
compounds by sediments, soils, and suspended solids - I.
Theory and background. Wat. Res. 17(10):1433-1441.
Wolf, D. C., T. H. Dao, H. D. Scott, and T. L. Lavy. 1989.
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24
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United States Office ot Office of Sona EPA.540-»-9i 003
Environmental Protection Researc.n ana Waste Marcn 1991
Agency Development ana Emergency
Response
&EPA Ground-Water Issue
CHARACTERIZING SOILS FOR
HAZARDOUS WASTE SITE ASSESSMENTS
R. P. Breckenridge', J. R. Williams2, and J. F. Keck'
INTRODUCTION
The Regional Superfund Ground Water
Forum is a group of ground-water scientists
representing EPA's Regional Offices, orga-
nized to exchange up-to-date information re-
lated to ground-water remediation at hazard-
ous waste sites. Soil characterization at
hazardous waste sites is an issue identified by
the forum as a concern of CERCLA decision-
makers.
To address this issue, this paper was pre-
pared through support from EMSL-LV and
RSKERL, under the direction of R. P.
Breckenridge, with the support of the
Superfund Technical Support Project. For
further information contact Ken Brown, EMSL-
LV Center Director, at FTS 545-2270 or R. P.
Breckenridge at FTS 583-0757.
Site investigation and remediation under the
Superfund program is performed using the
CERCLA remedial investigation/feasibility
study (RI/FS) process. The goal of the Rl/FS
process is to reach a Record of Decision
(ROD) in a timely manner. Soil characteriza-
tion provides data types required for decision
making in three distinct Rl/FS tasks:
1. Determination of the nature and extent of
soil contamination.
2. Risk assessment, and determination of
risk-based soil dean-up levels.
3. Determination of the potential effective-
ness of soil remediation alternatives.
Identification of data types required for the first
task, determination of the nature and extern of
contamination, is relatively straightforward.
The nature of contamination is related to the
types of operations conducted at the site.
Existing records, if available, and interviews
with personnel familiar with the site history are
good sources of information to help determine
the types ot contaminants potentially present.
This information may be used to shorten the
list of target analytes from the several hundred
contaminants of concern in the 40 CFR Part
264 list (Date 7-1-89). Numerous guidance
documents are available for planning all
' Idaho National EnginMnng Latentay, Emtronrntntal Saanca and Ttdwotogy Group. Maho Fails. ID 83415.
> Soil Soanttt, U.S. EPA/fi. S. Karr Envtronmantai Rasaaich laboratty, Ada, OK 74820
/t \
^ I *JT»otcqy 4
O 0 2
X"~J
Superfund Technology Stpport Center for Monitoring
and Site Characterization. Environmental Monitoring
Systems Laboratory Las Vegas, NV
Superfund Technology Support Center for
Ground-Water Fate and Transport, Robert S. Kerr
Environmental Research Laboratory Ada, OK
Tednoiogy Iwovatai Office
Office rtSo§dWa«B and Emergen^ Response,
U.S. EPA, Washington, D.C.
Water W. Kovaft*. Jr.. PhJX, Director
Printed on Recycled Paper
-------
asoects of the suDsequent samDlmg effort (US EPA. 1987a.
1988a. 1988b, and Jenkins et al., 1988).
The extent of contamination is also related to the types of
operations conductea at the site. Existing records, if available,
and interviews with personnel familiar with the site history are
also good sources of information to help determine the extent of
contamination potentially present. The extent of contamination
is dependent on the nature of the contaminant source(s) and the
extent of contaminant migration from the source(s). Migration
routes may inciude air, via volatilization and fugitive dust emis-
sions; overland flow; direct discharge; leachate migration to
ground water and surface runoff and erosion. Preparation of a
preliminary site conceptual model is therefore an important step
in planning and directing the sampling effort. The conceptual
model should identify the most likely locations of contaminants
in soil and the pathways through which they move.
The data type requirements for tasks 2 and 3 are frequently less
well understood. Tasks 2 and 3 require knowledge of both the
nature and extent of contamination, the environmental fate and
transport of the contaminants, and an appreciation of the need
for quality data to select a viable remedial treatment technique.
Contaminant fate and transport estimation is usually performed
by computer modeling. Site-specific information about the soils
in which contamination occurs, migrates, and interacts with, is
required as input to a model. The accuracy of the model output
is no better than the accuracy of the input information.
The purpose of this paper is to provide guidance to Remedial
Project Managers (RPM) and On-Scene Coordinators (OSC)
concerning soil characterization data types required for
decision-making in the CERCLA Rl/FS process related to risk
assessment and remedial alternative evaluation for contami-
nated soils. Many of the problems that ansa are due to a lack of
understanding the data types required for tasks 2 and 3 above.
This paper describes the soil charactenzation data types re-
quired to conduct model based risk assessment for task 2 and
the selection of remedial design for task 3. The information
presented in this paper is a compilation of current information
from the literature and from expenence combined to meet the
purpose of this paper.
EMSL-Las Vegas and RSKERL-Ada convened a technical
committee of experts to examine the issue and provide technical
guidance based on current scientific information. Members of
the committee were Joe R. Williams, RSKERL-Ada; Robert G.
Baca, Robert P. Breckenridge, Alan B. Crockett, and John F.
Keck from the Idaho National Engineering Laboratory, Idaho
Falls. ID; Gretchen L Rupp. PE, University of Nevada-Las
Vegas; and Ken Brown, EMSL-LV.
This document was compiled by the authors and edited by the
members of the committee and a group of peer reviewers.
Charactenzation of a hazardous waste site should be done
using an integrated investigative approach to determine quickly
and cost effectively the potential health effects and appropriate
response measures at a site. An integrated approach involves
consideration of the different types and sources of contami-
nants, their fate as they are transported through and are parti-
tioned, and their impact on different parts of the environment.
CONCERNS
This caper addresses two concerns related to soil characteriza-
tion for CERCLA remedial response. The first concern is the
applicability of traditional soil classification methods to CERCLA
soil characterization. The second is the identification of soil
charactenzation data types required for CERCLA risk assess-
ment and analysis of remedial alternatives. These concerns are
related, in that the Data Quality Objective (DQO) process
addresses both. The DQO process was developed, in part, to
assist CERCLA decision-makers in identifying the data types,
data quality, and data quantity required to support decisions that
must be made dunng the Rl/FS process. Data Quality Objec-
tives for Remedied Response Activities: Development Process
(US EPA, 1987b) is a guidebook on developing DQOs. This
process as it relates to CERCLA soil characterization is dis-
cussed in the Data Quality Objective section of this paper.
Data types required for soil characterization must be determined
eariy in the Rl/FS process, using the DQO process. Often, the
first soil data types related to risk assessment and remedial
alternative selection available dunng a CERCLA site investiga-
tion are soil textural descriptions from the borehole logs pre-
pared by a geologist dunng investigations of the nature and
extent of contamination. These boreholes might include instal-
lation of ground-water monitonng wells, or soil boreholes. Typi-
cally, borehole logs contain soil lithology and textural descrip-
tions, based on visual analysis of drill cuttings.
Preliminary site data are potentially valuable, and can provide
modelers and engineers with data to begin preparation of the
conceptual model and perform scoping calculations. Soil tex-
ture affects movement of air and water in soil, infiltration rate,
porosity, water holding capacity, and other parameters.
Changes in lithology identify heterogeneities m the subsurface
(i.e., low permeability layers, etc.). Soil textural classification is
therefore important to contaminant fate and transport modeling,
and to screening and analysis of remedial alternatives. How-
ever. unless collected property, soil textural descriptions are of
limited value for the following reasons:
1. There are several different systems for classification of soil
particles with respect to size. To address this problem it is
important to identify which system has been or will be used
to classify a soil so that data can be property compared.
Figure 1 can be used to compare the different systems (Gee
arid Bauder, 1986). Keys to Soil Taxonomy (Soil Survey
Staff, 1990) provides details to one of the more useful
systems that should be consulted prior to classifying a site's
soils.
2. The accuracy of the field classification is dependent on the
skill of the observer. To overcome this concern RPMs and
OSCs should collect soil textural data that are quantitative
rather than qualitative. Soil texture can be determined from
a soil sample by sieve analysis or hydrometer. These data
types are superior to qualitative descnption based on visual
analysis and are more likely to meet DQOs.
3. Even if the field person accurately classifies a soil (e.g., as
a silty sand or a sandy loam), textural descnptions do not
afford accurate estimations of actual physical properties
required for modeling and remedial alternative evaluation,
2
-------
such as hydraulic conductivity For example, the hyaraulic
conductivity of silty-sana can range from 105 to ".0 ' cm/sec
(four orders of magnitude)
These ranges of values may be used for bounding calculations,
or to assist in preparation of the preliminary conceptual model.
These data may therefore meet DQOs for initial screening of
remedial alternatives, for example, but will likely not meet DQOs
for detailed analysis of alternatives.
DATA QUALITY OBJECTIVES
EPA has developed the Data Quality Objective (DQO) process
to guide CERCLA site characterization. The relationship be-
tween CERCLA RI/FS activities and the DQO process is shown
in Figure 2 (US EPA, 1988c, 1987a). The DQO process occurs
in three stages:
The types of decisions vary throughout the Rl/FS process but
in general tney become increasingly quantitative as the pro-
cess proceeds. During this stage it is important to identify and
involve the data users (e g. modelers, engineers, and scien-
tists), evaluate available data, develop a conceptual site
model, and specify ob|ectives and decisions.
Stage 2. Identify Data Uses/Needs. In this stage data uses
are defined This includes identification of the required data
types, data quality and data quantity required to make deci-
sions on how to:
- Perform risk assessment
- Perform contaminant fate and transport modeling
- Identify and screen remedial alternatives
Stage 1. Identify Decision Types. In this stage the types of
decisions that must be made during the RI/FS are identified.
PARTICLE SIZE UMTT CLASSIFICATION
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VERY FINE
SAND
VERY FINE
SAND
FINE
SAND
FINE
SAND
FINE
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MEDIUM
SANO
MEDIUM
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SAND
COARSE
SAND
COARSE
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QRAVEL
COBBLES
COBBLES
¦»
COBBLES
USDA - US DEPARTMENT OF AGRICULTURE. (SOIL SURVEY STAFF. 1975)
CCS - CANADA SOIL SURVEY COMMITTEE (McKEAGUE. 1978)
ISSS - INTERNATIONAL SOIL SCI SOC. (YONG AND WARKENT1N. 1966)
ASTM - AMERICAN SOCIETY FOR TESTING & MATERIALS (ASTM, D-2487.1985a)
Figure 1. Particle-size limits according to several current
classification schemes (Gee and Bauder, 1986).
• Stage 3. Design Data Collection Program. After Stage 1 and
2 activities have been defined and reviewed, a data collection
program addressing the data types, data quantity (nunber of
samples) and data quality required to make these decisions
needs to be developed as part of a sampling and analysis
plan.
Although this paper focuses on data types required for decision-
making in the CERCLA RI/FS process related to soil contami-
nation, references are provided to address data quantity quality
issues.
Data Types
The OSC or RPM must determine which soil parameters are
needed to make various RI/FS decisions. The types of deci-
sions to be made therefore dnve selection of data types. Data
types required for RI/FS activities including risk assessment,
contaminant fate and transport modeling and remedial alter-
native selection are discussed in Soil characteristics Data Types
Required for Modeling Section, and the Soil Characterization
Data Type Required for Remedial Alternative Selection Section.
Data Quality
The RPM or OSC must decide "How good does the data need
to be in order for me to make a given decision?". EPA has
assigned quality levels to different RI/FS activities as a guide-
line. Data Quality Objectives (or Remedial Response Activities
(US EPA, 1987a) offers guidance on this subject and contains
many useful references.
Data Quantity
The RPM or OSC must decide "How many samples do I need to
determine the mean and standard deviation of a given param-
eter at a given site?", or "How does a given parameter vary
spatially across the site?". Decisions of this type must be
addressed by statistical design of the sampling effort. The Soil
Sampling Quality Assurance Guide (Barth et al., 1989) and Data
Quality Objectives tor Remedial Response (US EPA, 1987a)
offer guidance on this subject and contain many useful refer-
ences.
3
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Figure 2. Phased RI/FS approach and the DQO process (EPA, 1987a).
4
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IMPORTANT SOIL CHARACTERISTICS IN SITE
EVALUATION
Tables 1 and 2 identify methods for collecting and determining
data types for soil characteristics either in the field, laboratory,
or by calculation. Soil characteristics in Table 1 are considered
the primary indicators that are needed to complete Phase I of the
RI/FS process. This is a short, but concise list of soil data types
that are needed to make CERCUV decisions and should be
planned for and collected early in the sampling effort. These
primary data types should allow for the initial screening of
remedial treatment alternatives and preliminary modeling of the
site for risk assessment. Many of these characteristics can be
obtained relatively inexpensively during periods of early field
work when the necessary drilling and sampling equipment are
already on site. Investigators should plan to collect data for all
the soil characteristics at the same locations and times soil
boring is done to install monitoring wells. Geophysical logging of
the well should also be considered as a cost effective method for
collecting lithologic information prior to casing the well. Data
quality and quantity must also be considered before beginning
collection of the appropriate data types.
The soil characteristics in Table 2 are considered ancillary only
because they are needed in the later stages and tasks of the
DQO process and the RI/FS process. If the site budget allows,
collection of these data types during early periods of field work
will improve the database available to make decisions on
remedial treatment selection and model-based risk assess-
ments. Advanced planning and knowledge of the need for the
ancillary soil characteristics should be factored into early site
work to reduce overall costs and the time required to reach a
ROD. A small additional investment to collect ancillary data
during early site visits is almost always more cost effective than
having to send crews back to the field to conduct additional soil
sampling.
Further detailed descnptions of the soil characteristics in Tables
1 and 2 can be found in Fundamentals of Soil Physics and Ap-
plications of Soil Physics (Hillel, 1980) and in a series of articles
by Dragun (1988, 1988a, 1988b). These references provide
excellent discussions of these characteristics and their influ-
ence on water movement in soils as well as contaminant fate and
transport.
SOIL CHARACTERISTICS DATA TYPES REQUIRED
FOR MODELING
The information presented here is not intended as a review of all
data types required for all models, instead it presents a sampling
of the more appropnate models used in risk assessment and
remedial design.
Uses of Vadose Zone Models for Cercla Remedial
Response Activities
Models are used in the CERCLA RI/FS process to estimate
contaminant fate and transport. These estimates of contami-
nant behavior in the environment are subsequently used for:
• Risk assessment. Risk assessment includes contaminant
release assessment, exposure assessment, and determining
nsk-based clean-up levels. Each of these activities requires
estimation of the rates and extents of contaminant movement
in the vadose zone, and of transformation and degradation
processes.
• Effectiveness assessment of remedial alternatives This
task may also require determination of the rates and extents
of contaminant movement in the vadose zone, and of rates
and extents of transformation and degradation processes.
Technology-specific data requirements are cited in the Soil
Characterization Data Type Required for Remedial Alterna-
tive Selection Section.
The types, quantities, and quality of site characterization data
required for modeling should be carefully considered during Rl/
FS scoping. Several currently available vadose zone fate and
transport models are listed in Table 3. Soil characterization data
types required for each model are included in the table Model
documentation should be consulted for specific questions con-
cerning uses and applications.
The Superfund Exposure Assessment Manual discusses vari-
ous vadose zone models (US EPA, 1988e). This document
should be consulted to select codes that are EPA-approved.
Data Types Required for Modeling
Soil characterization data types required for modeling are in-
cluded in Tables 1 and 2. Most of the models are one- or
two-dimensional solutions to the advection-dispersion equa-
tion, applied to unsaturated flow. Each is different in the extent
to which transformation and degradation processes may be
simulated; various contaminant release scenarios are accom-
modated; heterogeneous soils and other site-specific charac-
teristics are accounted for. Each, therefore, has different data
type input requirements.
All models require physicochemical data for the contaminants of
concern. These data are available in the literature, and from
EPA databases (US EPA, 1988c,d). The amount of physico-
chemical data required is generally related to the complexity of
the model. The models that account for biodegradation of
organics, vapor phase diffusion and other processes require
more input data than the relatively simpler transport models.
Data Quality and Quantity Required for Modeling
DQOs for the modeling task should be defined during RI/FS
scoping. The output of any computer model is only as valid as
the quality of the input data and code itself. Variance may result
from the data collection methodology or analytical process, or as
a result of spatial variability in the soil characteristic being
measured.
In general, the physical and chemical properties of soils vary
spatially. This variation rarely follows well defined trends; rather
it exhibits a stochastic (i.e., random) character. However, the
stochastic character of many soil properties tends to follow
classic statistical distributions. For example, properties such as
bulk density and effective porosity of soils tend to be normally
distributed (Campbell, 1985). Saturated hydraulic conductivity,.
in contrast, is often found to follow a log-normal distribution.
Characterization of a site, therefore, should be performed in
such a manner as to permit the determination of the statistical
characteristics (i.e., mean and variance) and their spatial
correlations.
(Continued on page 8)
5
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TABLE 1. MEASUREMENT METHODS FOR PRIMARY SOIL CHARACTERISTICS
NEEDED TO SUPPORT CERCLA DECISION-MAKING PROCESS
Measurement Technique/Method (w/Reference)
Soil Characteristic' Field
Laboratory
Calculation or Lookup Method
Bulk density
Soil pH
Texture
Depth to
ground water
Horizons or
stratigraphy
Hydraulic
conductivity
(saturated)
Water retention
(soil water
charactenstic
curves)
Air permeability
and water content
relationships
Porosity (pore
volume)
Climate
Neutron probe (ASTM, 1985),
Gamma raoiation (Blake and Hartage,
1986, Blake, 1965)
Measured in field in same manner as
in laboratory.
Collect composite sample for each soil
type. No held methods are available,
except through considerable
experience of "feeling" the soil for an
estimation of % sand, silt, and clay.
Ground-water monitonng wells or
piezometers using EPA approved
methods (EPA 1985a).
Soil pits dug with backhoe are best. If
safety and cost a;e a concern, soil
bores can be collected with either a
thin wall sample driver and veilmayer
tube (Brown et al., 1990).
Auger-hole and piezometer methods
(Amoozeger and Wamck, 1986) and
Guelph permeameter (Reynolds &
Elnck, 1985; Reynolds & Elrick, 1986).
Field methods require a considerable
amount of time, effort, and equipment.
For a good discussion of these methods
refer to Bruce and Luxmoore (1986).
None
Coring or excavation for lab analysis
(Blake and Hartage. 1986).
Using a glass electrode in an aqueous
slurry (ref. EPRI EN-6637) Analytical
Method - Method 9045, SW-846, EPA.
ASTM D 522-63 Method for Particle
Analysis of Soils. Sieve analysis better at
hazardous waste sites because organics
can effect hydrometer analysis
(Kluate, 1986).
Not applicable.
Not applicable.
Constant head and falling head methods
(Amoozeger and Warrick, 1986).
Obtained through wetting or drainage of
core samples through a series of known
pressure heads from low to high or high
to low, respectively (Klute, 1986).
Several methods have been used,
however, all use disturbed soil samples.
For field applications the structure of
soils are very important, For more
information refer to Corey (1986).
Gas pycnometer (Danielson and
Sutherland, 1986).
Precipitation measured using either
Sacramento gauge for accumulated value
or weighing gauge or tipping bucket gauge
for continuous measurement (Finkelstein
et al., 1983; Kite, 1979). Soil temperature
measured using thermocouple.
Not applicable.
Not applicable
Not applicable.
Not applicable.
Not applicable.
May be possible to obtain information
from SCS soil survey for the site.
Although there are tables available that
list the values for the saturated
hydraulic conductivity, it should be
understood that the values are given for
specific soil textures that may not be the
same as those on the site.
Some look-up and estimation methods
are available, however, due to high
spatial variably in this characteristic
they are not generally recommended
unless their use is justified.
Estimation methods for air permeability
exist that closely resemble the estimation
methods for unsaturated hydraulic
conductivity. Example models those
developed by Brooks and Corey (1964)
and van Genuchten 11980).
Calculated from panicle and bulk
densities (Danielson and Sutherland,
1986).
Data are provided in the Climatic Atlas of
the United States or are available from
the National Climate Data Center,
Asheville, NC Telephone (704) 259-0682.
Soil characteristics are discussed in general except where specific cases relate to different waste types (i.e., metals, hydrophobic orgaracs or polar organics).
6
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TABLE 2. MEASUREMENT METHODS FOR ANCILLARY SOIL PARAMETERS
NEEDED TO SUPPORT CERCLA DECISION-MAKING PROCESS
Measurement Technique/Method (w/Reference)
Soil Characteristic' Field
Laboratory
Calculation or Lookup Method
Organic caroon Not applicable
Capacity Exchange See Rhoades for field methods.
Capacity (CEC)
High temperature combustion (either
wet or dry) and oxidation techniques
(Powell et al, 1989) (Powell, 1990)
(Rhoades. 1982).
Erodibility
Water erosion
Universal Soil Loss
Equation (USLE)
or Revised USLE
(RUSLE)
Wind erosion
Vegetative cover
Soil structure
Organic carbon
partition
cooefficient (KJ
Redox couple ratios
of waste/soil svstem
Measurement/survey of slope (in ft
nse/ft run or %), length of field,
vegetative cover
Air monitoring for mass of containment.
Field length along prevailing wind
direction.
Visual observation and documented
using map. USDA can aid in identification
of unknown vegetation.
Classified into 10 standard kinds - see
local SCS office for assistance (Soil
Survey Staff, 1990) or Taylor and
Ashcroft (1972), p. 310.
In situ tracer tests (Freeze and Cherry,
1979).
Platium electrode used on lysimeter
sample (ASTM, 1987).
Not applicable
Not applicable.
Not applicable.
Not applicable.
(ASTM E 1195-87,1988)
Same as field.
Not applicaDle
Estimated using standard equations and
graphs (Israelsen et ai, 1980) field data
for slope, field length, and cover type
required as input. Soils data can be
obtained from the local Soil Conservation
Service (SCS) office
A modified universal soil loss equation
(USLE) (Williams, 1975) presented in
Mills et al, (1982) and US EPA (I988d)
source for equations.
The SCS wind loss equation (Israelsen
et al., 1980) must be adjusted (reduced)
to account for suspended particles of
diameter <10pm Cowherd et al., (1985)
for a rapid ev^uation (<24 hr) oi particle
emission fro a Superfund site
See local soil survey for the site
Calculated from K , water solubility
(Mills et al., 1985;Sims et al.. 1986).
Can be calculated from concentrations of
redox pairs or 02 (Stumm and Morgan, 1981).
Uner soil/water In situ tracer tests (Freeze and Cherry,
partition coefficient 1979)
Soil oxygen 02 by membrane electrode 02 diffusion
content (aeration) rate by Pt microelectrode (Phene, 1986).
Oj by field GC (Smith, 1983).
Batch experiment (Ash et al., 1973);
column tests (van Genuchlen and
Wierenga, 1986)
Same as field.
Mills et al., 1985.
Calculated from pE (Stumm and Morgan,
1981) or from 02 and soil-gas diffusion
rate.
(Continued)
7
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TABLE 2. (CONTINUED)
Measurement Technique/Method (w/Reference)
Soil Characteristic' Field
Laboratory
Calculation or Lookup Method
Soil temperature (as Thermotery (Taylor and Jackson. 1986)
it affects volatilization)
Clay mineralogy Parent material analysis.
Unsaturated
hydraulic
conductivity
Moisture content
Same as field.
Soil biota
Brown and Associates (1980)
Unsteady dranage-fiux (or instantaneous
profile) method and simplified unsteady
drajnage flux method (Green et al,
1986).The inslantaneous profile method
was initially developed as a laboratory
method (Watson, 1966), however rt was
adapted to the field (Hillel et al., 1972).
Constant-head borehole inflitration
(Amoozegar and Warrick, 1986).
Two types of techniques - indirect and
direct. Direct menthods, (i.e., gravimetnc
sampling), considered the most accurate,
with no calibration required. However,
methods are destructive to field systems.
Methods involve collecting samples,
weighing, drying and re-weighing to
determine field moisture. Indirect methods
rely on calibration (Klute, 1986).
No standard method exists (see model or
remedial technology for input or remedial
evaluation procedures).
X-ray diffraction (Whittig and Allardice, 1986).
Not usually done; results very difficult to
obtain.
A number of estimation methods exists,
each with their own set of assumptions
and requiremnts. Reviews have been
presented by Mualem (1986), and
van Gehuchten (in press).
No standard method exists; can use agar
plate count using MOSA method 99-3
p. 1462 (Klute. 1986).
Soil characteristics are discussed in general except where specific cases relate to different waste types (i.e., metals, hydrophobic organics or polar organics).
Significant advances have been made in understanding and
describing the spatial variability of soil properties (Neilsen and
Bouma, 1985). Geostatistical methods and techniques (Clark,
1982; Davis, 1986) are available for statistically characterizing
soil properties important to contaminant migration. Information
gained from a geostatistical analysis of data can be used for
three major purposes:
• Determining the heterogeneity and complexity of the site;
• Guiding the data collection and interpretation effort and thus
identifying areas where additional sampling may be needed
(to reduce uncertainty by estimating error); and
• Providing data for a stochastic model of fluid flow and con-
taminant migration.
One of the geostatistical tools useful to help in the interpolation
or mapping of a site is referred to as kriging (Davis, 1986).
General kriging computer codes are presently available. Ap-
plication of this type of tool, however, requires an adequate
sample size. As a rule of thumb, 50 or more data points are
needed to construct the semivanogram required for use in
knging. The benefit of using kriging in site charactenzation is
that it allows one to take point measurements and estimate soil
characteristics at any point within the domain of interest, such as
grid points, for a computer model. Geostatistical packages are
available from the US EPA, Geo-EAS and GEOPACK (Englund
and Sparks, 1988 and Yates and Yates, 1990).
The use of stochastic models in hydrogeology has increased
significantly in recent years. Two stochastic approaches that
have been widely used are the first order uncertainty method
(Dettinger and Wilson, 1981) and Monte Carlo methods (Clifton
et al., 1985; Sagar et al., 1986; Eslinger and Sagar, 1988).
Andersson and Shapiro (1983) have compared these two ap-
proaches for the case of steady-state unsaturated flow. The
Monte Carlo methods are more general and easier to implement
than the first order uncertainty methods. However, the Monte
Carlo method is more computationally intensive, particularly for
multidimensional problems.
(Continued on page 10)
8
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TABLE 3. SOIL CHARACTERISTICS REQUIRED FOR VADOSE ZONE MODELS
Model Name
[References)]
Properties and Parameters
x <
Sesoil
(C,D)
Creams
(E,F)
PRZM
(G,H,I)
Vadott
(H,j)
Minteq
(J)
Fowl™
(K)
Ritz
(L)
Vip
(M)
Chemflo
(N)
Soil bulk density
0
•
•
•
•
0
•
•
•
•
Soil pH
0
•
o
O
o
•
•
0
o
0
Soil texture
•
0
•
•
•
o
0
•
•
0
Depth to ground water
o
•
0
0
•
o
0
0
o
o
Horizons (soil layering)
•
•
•
•
•
0
0
0
0
o
Saturated hydraulic conductivity
•
•
•
•
•
o
•
•
•
•
Water retention
•
•
•
•
•
o
•
o
o
•
Air permeability
o
•
o
o
o
o
o
o
•
0
Climate (precipitation)
•
•
•
•
o
o
•
•
•
•
Soil porosity
•
•
•
•
•
o
0
•
•
o
Soil organic content
0
•
•
•
•
•
o
•
•
o
Cation Exchange Capacity (CEC)
0
•
o
0
0
•
o
o
o
o
Degradation parameters
•
•
•
•
•
0
o
•
•
•
Soil grain size distnbution
0
o
o
0
0
o
0
o
o
0
Soil redox potential
o
0
o
o
o
•
o
o
o
o
Soil/water partition coefficients
0
•
•
•
•
•
•
•
•
•
Soil oxygen content
0
o
o
0
0
0
o
0
•
0
Soil temperature
0
•
0
•
•
•
o
•
•
o
Soil mineralogy
0
•
0
o
o
o
0
0
0
0
Unsaturated hydraulic conductivity
•
•
•
•
•
o
•
0
0
•
Saturated soil moisture content
•
•
•
•
•
o
•
•
•
•
Microorganism population
o
o
o
0
o
o
0
o
0
0
Soil respiration
o
o
0
0
o
o
0
o
o
o
Evaporation
•
•
•
•
0
o
0
•
•
•
Air/water contaminant densities
0
0
o
0
o
0
•
•
•
o
Air/water contaminant viscosities
o
0
o
0
0
o
o
o
0
0
A. Schioedef, etal., 1984. F. Devaurs and Springer, 1988. K. Hosteller, Erickson, and Rai, 1988. •Required O Not required O Used indirectly
B. Schroeder,etal., 1984a. G. Careet etal., 1384. L Notoger andWillaira. 1988. * used intheressmatonol other required
C. Bonazcuntas and Wagner, 1984. H. Dear etal., 1989. M. Stevens etal..1989. characteristics or the intrpretaton of the models,
D. Chen. Wollman, and Liu, 1987. I. Dean etal., 1989a. N. Notoger etal., 1989. but not directly entered as input to models.
E. Leonaid and Feneira, 1984. J. Brown and AlSson, 1987.
9
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Application of stochastic models to hazardous waste sites has
two main advantages. First, this approach provides a rigorous
way to assess the uncertainty associated with the spatial vari-
ability of soil properties. Second, the approach produces model
predictions in terms of the likelihood of outcomes, i e., probabil-
ity of exceeding water quality standards. The use of models at
hazardous waste sites leads to a thoughtful and objective
treatment of compliance issues and concerns.
In order to obtain accurate results with models, quality data
types must be used. The issue of quality and confidence in data
can be partially addressed by obtaining as representative data
as possible. Good quality assurance and quality control plans
must be m place for not only the acquisition of samples, but also
for the application of the models (van der Heijde, et al., 1989).
Specific soil characteristics vary both laterally and vertically in
an undisturbed soil profile. Different soil characteristics have
different variances. As an example, the sample size required to
have 95 percent probability of detecting a change of 20 percent
in the mean bulk density at a specific site was 6; however, for
saturated hydraulic conductivity the sample size would need to
be 502 (Jury, 1986). A good understanding of site soil charac-
teristics can help the investigators understand these variations.
This is especially true for most hazardous waste sites because
the soils have often been disturbed, which may cause even
greater variability.
An important aspect of site characterization data and models is
that the modeling process is dynamic, i.e., as an increasing
number of "simplifying" assumptions are needed, the complexity
of the models must increase to adequately simulate the addi-
tional processes that must be included. Such simplifying as-
sumptions might include an isotropic homogeneous medium or
the presence of only one mobile phase (Weaver, et al., 1989).
In order to decrease the number of assumptions required, there
is usually a need to increase the number of site-specific soil
characteristic data types in a model (see Table 2); thus providing
greater confidence in the values produced. For complex sites,
an iterative process of initial data collection and evaluation
leading to more data collection and evaluation until an accept-
able level of confidence in the evaluation can be reached can be
used.
Table 3 identifies selected unsaturated zone models and their
soil characteristic needs. For specific questions regarding use
and application of the model, the reader should refer to the
associated manuals. Some of these models are also reviewed
by Donigan and Rao (1986) and van der Heijde et al. (1988).
SOIL CHARACTERISTICS DATA TYPES REQUIRED
FOR REMEDIAL ALTERNATIVE SELECTION
Remedial Alternative Selection Procedure
The CERCLA process involves the identification, screening and
analysis of remedial alternatives at uncontrolled hazardous
waste sites (US EPA, 1988c). During screening and analysis,
decision values for process-limiting characteristics for a given
remedial alternative are compared to site-specific values of
those characteristics. If site-specific values are outside the
range required for effective use of a particular alternative, that
alternative is less likely to be selected. Site soil conditions are
critical process-limiting characteristics.
Process-Limiting Characteristics
Process-limiting characteristics are site- and waste-sDecific
data types that are critical to the effectiveness and ability to
implement remedial processes. Often, process-limiting charac-
teristics are descriptors of rate-limiting steps in the overall
remedial process. In some cases, limitations imposed by
process-limiting characteristics can be overcome by adjustment
of soil characteristics such as pH, soil moisture content, tem-
perature and others. In other cases, the level of effort required
to overcome these limitations will preclude use of a remedial
process.
Decision values for process limiting characteristics are increas-
ingly available in the literature, and may be calculated for
processes where design equations are known. Process limiting
characteristics are identified and decision values are given for
several vadose zone remedial alternatives in Table 4. For
waste/site characterization, process-limiting characteristics
may be broadly grouped in four categories:
1. Mass transport characteristics
2. Soil reaction characteristics
3. Contaminant properties
4. Engineering characteristics
Thorough soil characterization is required to determine site-
specific values for process-limiting characteristics. Most reme-
dial alternatives will have process-limiting characteristics in
more than one category.
Mass Transport Characteristics
Mass transport is the bulk flow, or advection of fluids through
soil. Mass transport charactenstics are used to calculate
potential rates of movement of liquids or gases through soil and
include:
Soil texture
Unsaturated hydraulic conductivity
Dispersivity
Moisture content vs. soil moisture tension
Bulk density
Porosity
Permeability
Infiltration rate, stratigraphy and others.
Mass transport processes are often process-limiting for both in
situ and extract-and-treat vadose zone remedial alternatives
(Table 4). In situ alternatives frequently use a gas or liquid
mobile phase to move reactants or nutrients through contami-
nated soil. Alternatively, extract-and-treat processes such as
soil vapor extraction (SVE) or soil flushing use a gas or liquid
mobile phase to move contaminants to a surface treatment site.
For either type of process to be effective, mass transport rates
must be large enough to clean up a site within a reasonable time.
Soil Reaction Characteristics
Soil reaction characteristics describe contaminant-soil interac-
tions. Soil reactions include bio- and physicochemical reactions
that occur between the contaminants and the site soil. Rates of
reactions such as biodegradation, hydrolysis, sorption/desorp-
tion, precipitation/dissolution, redox reactions, acid-base
reactions, and others are process-limiting characteristics for
(Continued on page 12)
10
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TABLE 4. SOIL CHARACTERIZATION CHARACTERISTICS
(US EPA. 1988e,f: 1989a,b: 1990; Simset
Technology
Process
Limiting Characteristics
Site Data
Required
Pretreatment/
materials handling
Large particles interfere
Clayey soils or hardpan
difficult to handle
Particle size
distnbution
Wet soils difficult
to handle
Soil moisture content
Soil vapor
extraction
Applicable only to volatile
organics w/significant vapor
pressure >1 mm Hg
Contaminants
present
Low soil permeability inhibits
air movement
Soil permeability
Soil hydraulic conductivity
>1E-8 cm/sec required
Hydraulic
conductivity
Depth to ground water
>20 ft recommended
Depth to ground water
High moisture content
inhibits air movement
Soil moisture content
High organic matter
content inhibits
contaminant removal
Organic matter content
In situ enhanced
bioremediation
Applicable only to
specific organics
Contaminants present
Hydraulic conductivity
>lE-4 cm/sec preferred
to transport nutnents •
Hydraulic conductivity
Stratification should be
minimal
Soil stratigraphy
Lower permeability layers
difficult to remediate
Soil stratigraphy
Temperature 15-45°C
required
Soil temperature
Moisture content 40-80%
of that at -1/3 bars tension
preferred
Soil moisture
characteristic curves
pH 4.5-6.5 required
Soil pH
Presence of microbes
required
Rate count
Minimum 10% air-filled
porosity required for
aeration
Porosity and soil
moisture content
Thermal treatment Applicable only to organics Contaminants present
Soil moisture content Soil moisture content
affects handling and
heating requirements
REQUIRED FOR REMEDIAL TECHNOLOGY EVALUATION ,
al„ 1986; Sims, 1990; Towers et al., 1989)
Technology
Process
Limiting Characteristics
Site Data
Required
Thermal treatment
(continued)
Particle size affects
feeding and residuals
Particle size
distribution
pH <5 and >11 causes
corrosion
pH
Solidification/
stabilization
Not equally effective for
ail contaminants
Contaminants
present
Fine particles < No. 200
mesh may interfere
Particle size
distribution
Oil and grease >10%
may interfere
Oil and grease
Chemical
extraction
(slurry reactors)
Not equally effective
for all contaminants
Particle size <0.25 in.
Contaminants
present
Particle size
distnbution
pH <10
pH
Soil washing
Not equally effective
for all contaminants
Contaminants
present
Silt and clay difficult
to remove from wash
fluid
Particle
size distribution
Soil flushing
Not equally effective
for all contaminants
Contaminants
present
Required number of
pore volumes
Infiltration rate
and porosity
Glycolate
dechlorination
Not equally effective
for all contaminants
Contaminants
present
Moisture content <20%
Moisture content
Low organic matter
content required
Organic carbon
Chemical oxidation/
reduction (slurry
reactor)
Not equally effective
for all contaminants
Oxidizabie organics
interfere
Contaminants
present
Organic carbon
pH <2 interferes
pH
In situ
vitrification
Maximum moisture
content of 25% by weight
Moisture
content
Particle size <4 inches
Requires soil hydraulic
conductivity <1E-5 cm/sec
Particle size
distribution
Hydraulic conductivity
11
-------
many remedial alternatives (Table 4) Soil reaction character-
istics include-
Ka, specific to the site soils and contaminants
Cation exchange capacity (CEC)
Eh
pH
Soil biota
Soil nutrient content
Contaminant abiotic/biological degradation rates
Soil mineralogy
Contaminant properties, described below, and others.
Soil reaction characteristics determine the effectiveness of
many remedial alternatives For example, the ability of a soil to
attenuate metals (typically described by Ka) may determine the
effectiveness of an alternative that relies on capping
and natural attenuation to immobilize contaminants.
Soil Contaminant Properties
Contaminant properties are critical to contaminant-soil interac-
tions, contaminant mobility, and to the ability of treatment
technologies to remove, destroy or immobilize contaminants.
Important contaminant properties include:
Water solubility
Dielectric constant
Diffusion coefficient
Koc
k
Molecular weight
Vapor pressure
Density
Aqueous solution chemistry, and others.
Soil contaminant properties will determine the effectiveness of
many treatment techniques. For example, the aqueous solution
chemistry of metal contaminants often dictates the potential
effectiveness of stabilization/solidification alternatives.
Soil Engineering Characteristics and Properties
Engineering characteristics and properties of the soil relate both
to implementability and effectiveness of the remedial action.
Examples include the ability of the treatment method to remove,
destroy or immobilize contaminants; the costs and difficulties in
installing slurry walls and other containment options at depths
greater than 60 feet; the ability of the site to withstand vehicle
traffic (trafficability); costs and difficulties in deep excavation of
contaminated soil; the ability of soil to be worked for implemen-
tation of in situ treatment technologies (tilth); and others.
Knowledge of site-specific engineering characteristics and
properties is therefore required for analysis of effectiveness and
implementability of remedial alternatives. Engineering charac-
teristics and properties include, but are not limited to:
T rafficability
Erodability
Tilth
Depth to groundwater
Thickness of saturated zone
Depth and total volume of contaminated soil
Bearing capacity, and others.
SUMMARY AND CONCLUSIONS
The goal of the CERCL^ RI/FS process is to reach a ROD in a
timely manner. Soil characterization is critical to this goal. Soil
characterization provides data for RI/FS tasks including deter-
mination of the nature and extent of contamination, risk as-
sessment, and selection of remedial techniques.
This paper is intended to inform investigators of the data types
required for RI/FS tasks, so that data may be collected as
quickly, efficiently, and cost effectively as possible. This
knowledge should improve the consistency of site evaluations,
improve the ability of OSCs and RPMs to communicate data
needs to site contractors, and aid in the overall goal of reaching
a ROD in a timely manner.
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