Office of Solid Waste         EPA 9902.3-1 a
                           and Emergency Response       July 1992
                           Washington, DC 20460	PB92-963614
          Office of Waste Programs Enforcement
&EPA   Corrective Action Glossary

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                                            EPA 9902.3-la
                                               April 1992
  CORRECTIVE ACTION GLOSSARY
Office of Solid Waste and Emergency Response
   Office of Waste Programs Enforcement
   U.S. Environmental Protection Agency
             401 M St. S.W.
          Washington, D.C. 20460

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                                   NOTICE
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy and approved for publication.  Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.

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                     CORRECTIVE ACTION GLOSSARY
INTRODUCTION

      This glossary of technical terms was prepared to facilitate the use of the Correc-
tive Action Plan (CAP) issued by OSWER on November 14, 1986. The CAP presents
model scopes of work for all phases of a corrective action program, including the RCRA
Facility Investigation (RFI), Corrective Measures Study (CMS), Corrective Measures
Implementation (CMI) and interim measures.

      Many technical terms are used in the CAP (e.g., matrix-spike, surrogate samples,
attenuation capacity, hydraulic conductivity, etc.). The Corrective Action Glossary
includes brief definitions of the technical terms and explains how they are used (e.g.,
field blanks are used to determine whether contamination is introduced through the
sample collection  activities or from the sampling environment). In addition,  expected
ranges (where applicable) are provided (e.g., hydraulic conductivity for sandy soil is
expected to be  1x10"* cm/sec).  Parameters or terms not discussed in the CAP, but
commonly associated with site investigations or remediations are also included.

      This document is not intended as a stand-alone site investigation/remediation
guidance, but as a supplement to other guidance such as the RCRA Facility Investigation
(RFI) Guidance (OSWER Directive  9502-00-6D). RCRA guidance documents can be
ordered by contacting the RCRA Docket Information Center, U.S. EPA, Washington,
D.C., (202) 260-9327 or the Center for Environmental Research Information  (CERI) in
Cincinnati, Ohio,  (513)  569-7562 or (FTS) 684-7562.

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                           CONTENTS
Section                                                         Page






Notice 	ii




INTRODUCTION 	3




GLOSSARY 	4




APPENDICES  	48

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                                   GLOSSARY
Absorption

Description: Penetration of a substance into another. Commonly used to refer to
absorption of a gas by a liquid.

Application:  Examples include: (1) infusion of oxygen into (subsurface) water for
bioremediation; (2) absorption of TCE by leachate; (3) scrubbing or removing gases (for
example, SOX, NOX, CH4) by a liquid solvent to purify a gas stream before venting the
gas stream to the atmosphere.
Adsorption

Description: A two-dimensional process in which one substance is attracted to and
adheres on the surface of a solid substance such as unsaturated soil, aquifer material, or
activated carbon. Typically, chemicals move to a solid phase from a fluid phase that may
be water, gas, or non-aqueous phase liquid (NAPL).  Rate and extent of adsorption
depends upon characteristics of the adsorbing agent as well as the chemical(s) and the
phase in which the chemical occurs, and therefore generally are measured in laboratory
or field tests.  In some cases adsorption may be reversed and the adsorbed material may
move into a fluid phase from a solid phase, referred to as desorption or stripping.

Application:  Adsorption of a chemical from a water phase by an adsorbing agent such
as subsurface aquifer material is commonly used to evaluate efficacy of pump and treat
remediation.  The following quantitative relationship is used:  Kd = CJC^ where Kd is
the partition coefficient that expresses relative concentration of a chemical in soil, Cs is
defined as concentration of chemical in the soil phase (mg/gm), and Cw is defined as
concentration of chemical in the water phase (mg/ml).  Thus, units of Kd are ml/gm.
The value of Kd is often used to evaluate the effect of adsorption on retardation of rate
of movement of a chemical compared with rate of movement of water  in the subsurface.
The relevant expression is: R =  1  + r Kd/n, where R is a retardation factor which
quantitatively expresses the ratio of velocity of water to velocity of the  chemical, r is the
bulk density, Kd is the partition coefficient, and  n is the porosity of aquifer material.  As
an example, for a specific chemical/aquifer system with values for r of 1.4 gm/ml, Kd of
10 ml/gm, and  n of 0.30, the value of R is 47.7, indicating that water will move by
advection through the subsurface at a rate that is 47.7 times faster than the rate of
movement of the chemical.  Therefore, the volume of water required to remove the
chemical during pump and treat  would  be 47.7 more than one pore volume of aquifer
material to remove the chemical. Concerning metals, adsorption generally increases with
increasing pH;  however, adsorption of arsenate and arsenite forms will generally increase
with decreasing pH.

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Adsorbing agent  [adsorbent]

Description:  A substance that has the ability to condense or hold molecules of other
substances on its surface.

Application:  Examples include: (1) soil materials acting as adsorbing agents for
chemicals present in water (leachate) and gas phases in unsaturated and saturated
subsurface environments; (2) activated carbon used as an adsorbing agent to "scrub"
volatile organic chemicals present in off-gas emissions as a result of air stripping of
contaminated ground water.
Adsorbing reagent

Description: An adsorbing agent used to detect or measure molecules that sorb on its
surface.
Application: For example, Draeger tubes, used in field sampling and analysis, contain an
adsorbing agent that colorimetrically indicates concentrations of volatile organic
compounds.
Alkalinity  [of water]

Description: Acid-neutralizing capacity of a water. Alkalinity is a measure of capacity of
water to neutralize acids. It is primarily a function of bicarbonate, carbonate, and
hydroxide content.  Alkalinity, usually expressed as milligrams/liter (mg/L) of calcium
carbonate  (CaCO3), is a measure of buffering capacity (resistance to alteration in pH) of
water.  Most natural waters have substantial buffering capacity through dissolution of
carbonate-bearing minerals creating a carbonate/bicarbonate buffer system.  Some
components of alkalinity will combine with toxic heavy metals and greatly reduce their
toxicity.

Application: Alkalinity is a widely used  indicator  to characterize water; it may also help
define an appropriate treatment for wastes.  The pH of waters with low alkalinity are
more easily modified.  This is useful when lowering pH is desirable (i.e., in order to
leach many metals  in the process of soil  washing or flushing), or conversely, increasing
pH in order to precipitate  metals in the  process of immobilization or attenuation.

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Appendix VIII constituents

Description: Appendix VIII in 40 CFR Part 261 is EPA's list of RCRA hazardous
constituents.  It is comprised of chemicals which have toxic, carcinogenic, mutagenic or
teratogenic effects on humans or other life forms. It includes chemicals from the priority
pollutants list under the Clean Water Act, chemicals considered hazardous to transport
under Department of Transportation, chemicals identified as carcinogens by EPA's
Carcinogen Assessment Group, and chemicals which have a high acute toxicity as
identified by NIOSH's Registry of Toxic Effects of Chemical Substances list.  There are
currently 418 chemicals or classes of chemicals on Appendix VIII.

Application: The main purpose of Part 261, Appendix VIII is to identify the universe of
chemicals of concern under RCRA.  EPA uses Appendix VIII to determine if a waste
contains hazardous constituents and therefore should be considered for listing under 40
CFR Section 261.11 (Appendix VIII, however, should not be used by a generator
identifying hazardous  waste under Part 261, Subparts C & D.  Appendix VIII is much
broader than the actual hazardous waste lists in 40 CFR Sections 261.31-261.33.).
Owners/operators of RCRA facilities use Appendix  VIII for hazardous waste analysis
before incineration and when demonstrating clean-closure.
Appendix IX constituents

Description: Appendix IX in Part 264 is comprised of those constituents on the Part 261
Appendix VIII list, for which it is feasible to analyze in ground-water samples, plus 17
chemicals routinely monitored in the Superfund program.

Application: Pursuant to 40 CFR Part 264, Subpart F Ground-Water Monitoring
requirements, owner/operators of land-based hazardous waste disposal facilities that
have shown statistically significant increases over background concentrations for indicator
parameters, waste constituents, or reaction products, must analyze samples from all
monitoring wells at the compliance point to determine where Appendix IX constituents
are present and at what concentrations.  This analysis must be conducted at  least
annually.
ASTM classification [of soil]

Description: Definitions of soil types developed by the American Society for Testing and
Materials (ASTM). These definitions are primarily based on soil grain size, plasticity,
and strength.

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Application:  This information aids in estimating effects of a soil on infiltration and
retardation of chemicals and leachates and can give an indication of hydraulic
conductivity.  For example, retardation of a chemical generally increases as clay content
increases. Greater hydraulic conductivity makes it more feasible to introduce materials
such as water, air, oxygen, etc., to accomplish remediation using pump and treat, soil
washing and flushing, bioremediation, soil vacuum extraction, etc.
Atmospheric pressure

Description: Pressure exerted by air, also known as barometric pressure. This pressure is
14.696 pounds per square inch (psi) at sea level, where it will support a column of
mercury 760 mm high (approximately 30 inches). Atmospheric pressure decreases with
altitude.

Application:  Atmospheric pressure affects water levels in piezometers under confined
conditions, and should be considered when measuring water levels in a  confined system.
Changes in atmospheric pressure can also affect soil gas migration, and may result in
"barometric pumping" of volatile chemicals out of surface soils into the  atmosphere.
Attenuation capacity

Description: Ability or tendency of a hydrogeologic unit to retard the transport rate, or
reduce concentrations of hazardous constituents migrating through the unit.
Contaminants present in soil or geologic materials with a low attenuation capacity are
transported greater distances over a given time than in materials with a high attenuation
capacity.  While slow-moving contaminants may take longer to reach a receptor, high
attenuation capacity may also increase time and cost required to achieve cleanup criteria.

Application:  Attenuation capacity often refers to ability of subsurface systems to
immobilize metals.  Attenuation capacities are indicated by high cation exchange
capacity (CEC), high clay content, and high organic matter (OM) or organic carbon
(OC).
Bacteria

Description:   Microscopic, usually single-celled, prokaryotic organisms which reproduce
by binary fission. Bacteria play an important role in ecological processes, and are
characterized by very diverse metabolic capabilities.  The vast majority of bacteria are
harmless or beneficial to man; many are essential.

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Application:   Bacteria play a vital role in environmental processes. Their primary
function is to decompose or biodegrade complex organic molecules in nature.  Therefore,
they are vital in carbon and nutrient cycling in natural systems.  Bacteria are utilized in
treatment of both domestic and industrial wastes. Biodegradation  of toxic or hazardous
wastes requires healthy populations of bacteria capable of metabolizing specific
molecules, (see Bioremediation)
Bench scale -   see Treatability Studies
Bioaccumulation

Description:  The processes whereby organisms remove contaminants present at non-
toxic levels from the surrounding environment, and accumulate or store these
contaminants in their tissues.  Bioaccumulation often results in contaminant
concentrations within specific tissues or organs of exposed organisms which are much
higher than concentrations in the organism's surrounding environment (see
Bioconcentration).  The concentration of contaminants often increases with each higher
step in the food chain as a result of bioaccumulation (see Biomagnification).

Application:  Bioaccumulation should be considered when evaluating the  impact of
releases on receptors and in migration pathways during risk assessments.  Many organic
contaminants such as PCBs and  pesticides tend to accumulate in fatty tissues. The
octanol:water partition coefficient (Kow) of an organic contaminant may indicate
tendency of a chemical to partition between fat tissue (assumed to be similar to octanol)
and water, and therefore indicate tendency to concentrate in body fat tissue after intake
from water or food.  Metals such as mercury and lead also tend to accumulate in target
organs, and are  often concentrated in bacterial or plant biomass.

Bioassay

Description:  A  test used to evaluate the biological effects of a chemical or a mixture of
chemicals by measuring its (their) effect on a living indicator organism.

Application:  Bioassays are commonly used to evaluate the effect of chemical addition on
soil microbial activity, and therefore indicate potential adverse effect on bioremediation
processes.  Commonly used bioassays include soil respiration measured as CO2 evolution,
dehydrogenase activity, and nitrification potential.  A decrease in activity  indicates
potential adverse effects on bioremediation rate and extent.  Other tests that measure
toxic effects on non-soil organisms to assess  the rate and extent of detoxification of a
waste/soil mixture include the Ames Salmonella typhimurium/mammalian microsome
mutagenicity test to measure aqueous and solid phase changes in mutagenicity, and the
Microtox assay to measure changes in the toxicity of leachate.


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Bioconcentration

Description:  The result of bioaccumulation.  Long-term exposure to contaminants which
bioaccumulate can lead to gradual increases in contaminants within individual organisms.
Concentration of contaminants in specific tissues or target organs can therefore increase
to toxic levels even though exposures are below acute toxicity thresholds. Common
locations where contaminants bioconcentrate include bacterial cell walls and inclusion
bodies, plant roots and leaves, and fatty tissues of animals (fat, liver, reproductive
organs)

Application:  Extent of bioconcentration is useful in evaluating exposure scenarios in risk
assessment. This is usually done through quantitative calculation of bioconcentration
factors (BCF).
Bioconcentration Factor (BCF)

Description: Ratio of the concentration of the constituent in the whole body of an
organism (e.g., a fish) or specific tissue (e.g., fat, liver) to the concentration in water.

Application:  Bioconcentration factors are often estimated to be proportional to the
octanol/water partition coefficient (kow).  Constituents exhibiting a BCF greater that 1.0
indicate  bioaccumulation, and thus potential magnification of risk. Generally,
constituents exhibiting a BCF greater than 100 cause the greatest  concern.
Biochemical oxygen demand (BOD)

Description:  BOD is the amount of dissolved oxygen required to meet the metabolic
needs of aerobic microorganisms in water high in organic matter, such as sewage.  While
BOD measures only biodegradable organics, non-biodegradable materials can exert a
demand on the available oxygen in an aquatic environment.  BOD may be a useful
indicator parameter if a release is due primarily to degradable organic wastes. National
Pollution Discharge Elimination System (NPDES) effluent discharge limits for BOD are
industry specific.

Application:  BOD is measured quantitatively as mg/L of oxygen required to satisfy the
oxygen demand of chemicals present in a liter of water, and  is usually reported as  oxygen
requirement over a 5-day period (i.e., BOD5).  A  major assumption is often made  that
the consumption of oxygen by microorganisms in the presence of a chemical is an
indication of the biodegradation of the chemical.  The relative aerobic biodegradability
of chemicals may be ranked using BOD5 to indicate the relative  oxygen demand.
Chemicals  that may be biodegradable at a low concentration may be toxic to
microorganisms at the concentration used in the BOD5 test and,  therefore, may not


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biodegrade under test conditions. Industrial and other hazardous chemicals may be
biodegradable, but require bacterial seeds adapted to the compounds before yielding an
accurate BOD test.
Biodegradability

Description:  Tendency of a substance to break down or decompose as a result of the
metabolic activities of microorganisms.  Factors that affect biodegradability of
contaminants include chemical characteristics (concentration, molecular structure, and
toxicity of the contaminants), and environmental characteristics (moisture content,
presence or absence of oxygen or other electron acceptors in the soil, availability of
contaminants to micro-organisms, availability of other organic and inorganic nutrients for
metabolism, and other factors such as pH and temperature), and microbial
characteristics (microbial populations and microbial adaptation or  acclimation).
Transformation products often have different physical, chemical and/or toxicological
characteristics than the original contaminants. These products also may be hazardous
constituents and should be considered in developing monitoring programs.

Application:  Biodegradability potential of a compound is important in determining
feasibility of using bioremediation as a treatment technology.  The greater the
biodegradation potential of a compound, the greater is the susceptibility of the
compound to a bioremediation process. Biodegradability  is often expressed
quantitatively as "half-life", or time required to decrease chemical concentration by 50%.
Most commonly, half-life is calculated based on a first-order kinetic model as follows: t^2
= -0.693/k, where t^2 is the half-life value, -0.693 is the natural logarithm of 0.5, and k is
the slope of the line describing decrease in concentration  of a chemical with increase in
time of reaction. Half-life values are calculated for specific chemical/environmental
conditions  as described above.  Shorter half-lives indicate  higher biodegradation
potential.   Estimates of aerobic biodegradability for several compounds are provided in
Table 3 of Appendix  1.
Biomagnification

Description:  Increasing concentration of contaminants  with each higher step in
ecosystem food chains as a result of bioaccumulation.  Critical levels of contaminants
may occur within specific populations high in ecological food chains.  Predators such as
raptors and fish therefore can receive much higher doses of contaminants than indicated
by ambient environmental concentrations.

Application:  The classic example of biomagnification is the impact of the pesticide DDT
on bird-of-prey (raptor) populations.  Reproductive failures in many raptor populations

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in the early 1960s were shown to be caused by high concentrations of DDT in
reproductive tissues.  The source of DDT was traced to prey populations.
Bioremediation

Description:  Includes any of a variety of engineered treatment alternatives which utilize
biological degradation or transformation of waste components to achieve remediation
goals.  Bioremediation systems can be grouped into ex-situ and in-situ approaches.
Types of systems include solid (soil), aqueous (ground water, leachate), or mixed phase
(slurry, subsurface aquifer).

Application:  Many contaminants are biodegradable under appropriate conditions.
Biodegradation represents a solution rather than a disposal technology; however, various
types of bioremediation systems are being evaluated as cost-effective alternative
technologies. Ex-situ treatment systems include prepared  bed soil reactors, composting,
soil slurry bioreactors, bioreactors for extracted ground water, forced-air soil pile
approaches, etc. In-situ systems include surface soil systems, recirculating ground water
(saturated zone), bioventing (unsaturated zone), and combination approaches.
Performance evaluations for this area of developing technology are beginning to  be
performed in full scale demonstrations.
Biotransformation [of the waste]

Description:  Refers to partial alteration of a parent compound into intermediate
products by microorganisms.  Intermediate products may be less or more toxic than the
parent compound.  This is an important process to consider when selecting constituents
to monitor, as both parent and intermediate constituents may be transformed over time.
Samples generated from different phases of the  subsurface in microcosm studies can be
analyzed for intermediate product generation and degradation in order to evaluate the
rate and extent of treatment of a parent compound.

Application:  An  example of a biotransformation reaction that results in formation of a
more toxic intermediate compound is the  conversion, under anaerobic conditions, of
trichloroethylene  (TCE) to vinyl chloride  (VC).  VC is a known human carcinogen and is
more persistent under anaerobic conditions than TCE.  Under aerobic conditions, TCE
may be biotransformed to TCE-epoxide, an intermediate that is toxic to microorganisms
transforming TCE.  Another example is biotransformation of polycyclic aromatic
hydrocarbons (PAHs) in the human liver and by some soil fungi to chemical epoxide
intermediates, which are mutagenic, but can be  easily degraded biologically and
chemically through hydrolytic mechanisms.
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Blanks [analytical, quality assurance]

Description:

      Equipment blanks (or rinsate blanks) - Laboratory-distilled, deionized water that
      is poured through decontaminated field equipment and then collected in sample
      bottles for analysis.  Equipment blanks are used to determine whether
      contamination was introduced from sample collection equipment.

      Field blanks  A water sample collected for analysis by placing laboratory
      distilled, deionized water directly into a sample container in the field during and
      at the location of field samples. Field blanks are used to determine whether
      contamination is introduced from sample containers or sampling methodology,
      such as contact with air.

      Method blanks - Laboratory-distilled, deionized water that is subjected to the
      same laboratory procedures as samples.  Method blanks are prepared and
      analyzed in the laboratory to determine whether contamination is introduced from
      the  analytical process.

      Trip blanks  Laboratory-distilled, deionized water in a sample container that
      accompanies empty sample bottles to the field as well as samples returning to the
      laboratory for analysis. Trip blanks are used to determine whether contamination
      was introduced to the sample from air on the site or during shipping or storage.
Bulk density

Description:  Mass of dry soil per unit volume, including air space.  Bulk density values
are affected by soil structure (for example, degree of compaction) and texture (for
example, clay content and type).  Dry bulk density values are typically 1.6 - 1.8 g/cm3for
sandy soils, 1.3 - 1.6 g/cm3 for loamy soils, and 1.0-1.3 g/cm3 for clayey soils and soils
high in organic content.

Application:  Bulk density values can give an indication of porosity of a soil, which is
important in  evaluation of permeability  and in selection of remedial technologies.
Porosity is calculated by: % Porosity =  (1 - Bulk Density/Particle Density) x 100, where
particle density is defined as dry mass of soil particles divided by solid (not bulk) volume
of the particles. Bulk density values are  also used in calculation/characterization of
retardation of contaminants (See Adsorption).
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Calibration gases [zero and span]

Description:  Gases used to calibrate sampling or analytical equipment.

Application: A zero gas is a gas that has been certified as being free from contaminants
being measured; this gas is used to ensure that the scale on the instrument being
calibrated reads zero when no contaminants are present.  A span gas is a standard gas
whose properties are well-known, and which is present at a known  concentration;  this gas
is used to ensure that the analyzer instrument is set for the concentration range of
contaminants to be measured.
Cation

Description:  An ion having a positive charge (such as an oxidized metal) with a
tendency to attract anions and/or negative ends of molecules.

Application:  Many metals are cations (for example, lead, zinc, trivalent mercury, and
cadmium). Quantitative application with regard to  attenuation and treatment is in the
measurement of cation exchange capacity (CEC).
Cation exchange capacity (CEC)

Description:  Ability of a formation or material to adsorb positively charged atoms or
molecules such as metal ions. For example, CEC typically ranges from 5 to more than
200 milliequivalents per 100 grams of subsurface material (meq/100 grams).

Application:  CEC aids in predicting contaminant movement through soils and
availability of contaminants to geological systems. CEC is an important factor in
evaluating transport of lead, cadmium, and other toxic metals. Soils with a high CEC
will generally retain correspondingly high levels of these inorganics.
Chemical oxygen demand (COD)

Description:  A measure of chemically oxidizable material in water or wastewater,
including organic as well as some inorganic chemicals such as sulfides.  COD, generally
expressed as mg/L, may be a useful indicator parameter if a release is  due primarily to
degradable organic wastes.  NPDES effluent  discharge limits for COD  are industry
specific.
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Application:  COD is generally used in combination with BOD5 values.  COD may be
used to indicate presence of organic chemicals that are more recalcitrant or refractory to
microorganisms, and therefore are not reflected in the BOD5 test.  When COD values
are high and BOD values are low for a sample, the waste may contain complex organic
chemicals that require treatment through physical or chemical processes rather than
through biological treatment.
Chemical transformation

Description:  Chemical degradation processes, including chemical oxidation, reduction,
hydrolysis and photolysis, that change a chemical into one or more new chemical species.
This factor is important in evaluating fate of chemicals in the environment and should be
considered in designing sampling and analysis programs (see photolysis and hydrolysis).

Application: Chemical transformation may represent the major initial or subsequent
degradation pathways for many chemicals, and should be measured in treatability studies
in order to assess efficacy of utilizing chemical treatment methods. Chemical
transformations through hydrolysis are important for many pesticides as well as epoxides
or chlorinated aliphatic compounds.  For example, TCE-epoxide can be easily hydrolyzed
in ground water and soil environments. Photolysis reactions are  important for many
chemicals volatilizing into the atmosphere or present at the surface of soil.
Concentration profiles

Description:  Graphical representations of the horizontal and vertical locations
(distribution) of contaminant concentration levels on maps and cross sections.

Application:  Concentration profiles are prepared as part of site characterization
activities, and indicate the relative homogeneity or heterogeneity of contamination at a
site. These profiles help illustrate the  nature^ degree, and extent of contamination.
Based on this information,  strategies  are developed for placement of injection and
extraction wells for treatment as well  as for monitoring well locations in order to match
treatment location with contamination location.
Conductivity [electrical, of water]

Description:  A measure of the capacity of a water to conduct electric current (Also
known as specific conductance). Conductivity generally rises with increased concentration
of dissolved (ionic) species. The nature of dissolved substances, their actual and relative
concentrations, temperature, and ionic strength of the water sample affect specific
conductance.  Conductivity is expressed as micromhos/cm.


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Application:   Variations in specific conductance may indicate presence of contamination
release points.   Waters with high salinities or high total dissolved solids can be expected
to exhibit high conductivity. The RCRA Ground-Water Monitoring Technical
Enforcement Guidance Document (September 1986, OSWER 9950.1) recommends using
conductivity as a real-time  indicator of the representativeness of monitoring well water to
formation ground water. This application may be used when purging monitoring wells to
ensure collection of a representative sample.
                           Range of Values of Conductivity
Water Type
Freshly distilled water
Raw and finished waters
Highly mineralized water
Value (micromhos/cm)
0.5-2.0
50 - 500
500 - 1,000
Control charts [laboratory, process]

Description:  A graphical plot of test results to allow analysis and interpretation of
fluctuations of measurements on successive random samples.  Control charts are based
on means and standard deviations derived from repetitious analysis of known quality
control standards.  Control charts indicate whether the process or analytical method is in
control with respect to defined parameters.

Application:  Control charts are  used typically in chemical laboratories for verification of
quality of results.  Quality assurance samples are analyzed on a regular frequency to test
validity of the method.  Control  charts  are used in process monitoring over time, and are
important in ensuring internal quality control.
Demographics

Description:  Vital statistics of human populations, including size, growth, density, and
distribution.

Application:  This information aids in estimating human exposure to potential or actual
releases of contaminants, and therefore is used in risk assessment and risk management
models.
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Dense non-aqueous phase liquid (DNAPL)

Description:  A liquid that is not miscible with water and has a density greater than
water (> 1.0 gm/ml). Examples include chlorinated solvents such as trichloroethylene
(TCE), tetrachloroethylene (PCE), 1,1,1-trichloroethane  (TCA), carbon tetrachloride,
pentachlorophenols, dichlorobenzene, and creosote wood treating oils.  (See LNAPL and
Density). DNAPLs may be present in the unsaturated as well as saturated zone.  The
presence of DNAPLs complicates site characterization and generally decreases efficiency
of pump and treat systems in recovering subsurface contamination.  The high density of
DNAPLs provides a driving  force that can carry product deep into aquifers.

Application:  With regard to site characterization, DNAPLs may be present in the
unsaturated zone in four phases: gaseous, solid, aqueous, and immiscible hydrocarbon
(DNAPL). For example, TCE introduced into the subsurface as a DNAPL may partition
onto soil, volatilize into soil  gas, and solubilize into the water phase, resulting in
contamination of all four phases. In the saturated zone, TCE may also be present in the
solid, aqueous, and immiscible phases, but would not be  present in a gas phase.
Information concerning chemical properties, therefore, is important for designing site
characterization plans and for taking site samples. The combination of high density and
low viscosity is important with regard to transport of DNAPLs in the subsurface.
Subsurface drains have been used for recovery of DNAPLs from relatively shallow
aquifers (approximately 20 feet below ground surface).  A DNAPL recovery drainline is
placed below a water table depression drainline,  and both lines are pumped to
accomplish in situ subsurface separation of oil and water.
    Care must be taken when monitoring DNAPL in pools.  For example, if the  well
screen is located  entirely in  the DNAPL layer, the DNAPL will  rise in the well if the
hydrostatic head of water is  reduced by pumping or  bailing.  If the well screen extends
into the barrier layer, the DNAPL measured thickness will exceed that in the formation
by the length of the well below the barrier surface.  Both of these scenarios will  result in
a greater DNAPL thickness  in the well and thus  a false indication (overestimation) of
the actual DNAPL thickness will result (EPA 540/4-91/002).
Density

Description:  Mass of a material contained in a specific volume.  Generally expressed in
units of grams/cubic centimeter (g/cc).  Density of a compound indicates whether the
compound is heavier or lighter than water. (Density of water is approximately 1.0 g/cc -
see Specific gravity).  Liquid compounds with densities greater than 1.0 g/cc and of only
limited water solubility are referred to as dense non-aqueous phase liquids (see
DNAPLs) and may migrate vertically under influence of gravity.  Liquid compounds with
densities less than water and of only limited water solubility are referred to as light non-
aqueous phase liquids (see LNAPLs).
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Application:  Density information may be used to determine where a chemical spill or
release is likely to be found in the subsurface. DNAPLs may migrate downward under
influence of gravity until an impermeable layer is encountered.  LNAPLs tend to remain
associated with the top of a water table  and become smeared throughout a zone as a
result of water table fluctuation. Therefore, density information may be used to identify
where a waste is likely to migrate or be  located in the subsurface.  Values for this
parameter for selected contaminants are provided in Table 3 of Appendix 1.
Deposition area

Description:  Physical location(s) where particles of contaminants, sediment, etc.
suspended in water (or air) fall out of suspension.

Application:  Knowledge of past depositional environments helps identify stratigraphic
features that may influence contaminant migration.  This information aids in identifying
and evaluating past and current releases to ground water, surface-water, or air migration
pathways.
Discharge [of ground water]

Description:  Removal of water from the saturated zone to areas of discharge.
Generally, discharge areas are topographical lows at or near the surface of the land (i.e.,
streams, springs, wetlands, etc.).  Discharge occurs in response to differences in hydraulic
head.

Application:  This information helps determine ground-water flow direction and define
potential contaminant migration pathways.  Ground water flows from areas of high
hydraulic pressure (head) toward areas of lower hydraulic pressure.
Dissolved oxygen (DO) profiles

Description:  Graphical representation of dissolved oxygen as a function of depth or area
in lakes, rivers, ground water, unsaturated soil systems, etc., to obtain representative in
situ conditions which characterize redox status of the system.  Dissolved oxygen is
generally expressed as mg/L or as percent of saturation.  Profiles can be used to monitor
conditions at a specific point in time, or to monitor changes over time.   Generally for
surface  water, dissolved oxygen concentrations of less than 4 mg/L are  not adequate to
support most aquatic life. In unpolluted  surface water, oxygen is usuall}' present in
concentrations of 8 mg/L or more. In unsaturated soils, a minimum air-filled pore space
of 10 percent is usually required for aerobic metabolism.  Polluted ground-water systems
                                         16

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are often depleted of oxygen as a result of bacterial degradation of the contaminants and
minimal re-aeration potential.

Application:  Dissolved oxygen profiles may indicate presence of anaerobic or anoxic
zones where aerobic degradation may be inhibited.  DO profiles may be used for
monitoring and sampling purposes.  For example, when DO values at a contaminated
aquifer site increase from near zero to near saturation levels (about 10 mg/L),
bioremediation may be near completion. Core sampling and analysis may then be used
to confirm that no contamination remains in aquifer materials.  This approach also may
be useful at a site where bioremediation is  used for unsaturated soils, i.e., when surface
soil bioremediation or  bioventing is being applied to the site.  DO profiles may also be
useful in delineating areas of contamination.  Areas of low DO in either soil gas or
ground water may indicate high metabolic activity resulting from presence of
biodegrading contaminants.
Dynamic viscosity

Description:  Dynamic viscosity provides an indication of the ease with which a
compound (in its pure form) will flow. Dynamic viscosity has dimensions of mass per unit
length per unit time. The dynamic viscosity of water is approximately 1.0 centipoise (cp).

Application:  Mobility of a compound in its pure form is inversely proportional to its
dynamic viscosity. Mobility can be rated as high for compounds with values less than 0.6
cp, moderate for compounds with values between 0.6 and 1.0 cp, and low for compounds
with values greater than 1.0 cp.  Dynamic viscosity values for selected contaminants are
provided in Table 3 of Appendix 1.
Evapotranspiration

Description:  Combined water loss due to free-water and soil- moisture evaporation, and
plant transpiration. Along with surface runoff, evaporation must be subtracted from total
precipitation to determine infiltration rates.

Application:  Evapotranspiration rates are used to calculate infiltration rates, which are
required for the assessment of contaminant transport processes (e.g., leaching) in the
vadose (unsaturated) zone and recharge  potential to the ground water.  Also,
augmentation of evapotranspiration through use of vegetation may represent an
approach for decreasing downward migration of chemicals toward ground water and
allow destruction of contaminants within  the vadose zone by chemical  and/or biological
processes.
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Exchange capacity  See Cation exchange capacity (CEC).
Flash point

Description:  Lowest temperature at which a liquid or volatile solid gives off sufficient
vapor to form an ignitable mixture with air.

Application:  RCRA regulations in 40 CFR Part 261.21 use the flash point to determine
whether certain wastes exhibit the hazardous waste characteristic of ignitability. A liquid,
other than certain aqueous wastes, having a flash point less than 60° C (140° F) is a
RCRA hazardous waste.
Floodplain

Description:  Area bordering a stream or river that becomes flooded when the stream or
river overflows its channel. These areas are typically defined as 10-, 50- and 100-year
floodplains.
Application:  Delineation of a floodplain aids in evaluating potential for washout,
potential release to the surface-water  migration pathway, design of remedial actions,  and
assessment of siting of treatment, storage, or disposal facilities.
Freeboard

Description:  Vertical distance between the brim of an open-topped tank or surface-
impoundment and surface of the waste contained in the  tank or surface impoundment.

Application:  RCRA regulations for hazardous waste tank systems and surface
impoundments (40 CFR Parts 264 and 265, Subparts J and K, respectively)  require
owners or operators to maintain sufficient freeboard in uncovered tanks and surface
impoundments to prevent overtopping by wave or wind action or by precipitation.
Henry's Law

Description: Describes solubility of a gas in equilibrium with a liquid quantitatively as
Henry's law constant. Equilibrium partial pressure of a contaminant in air is
proportional to the solution concentration of contaminant.

Application:  Henry's Law is applied in evaluating the tendency of contaminants to
volatilize out of water into  surrounding air.
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Henry's Law Constant

Description: Indication of the partitioning ratio of a chemical between air and water
phases at equilibrium. Henry's law constant is directly proportional to vapor pressure of
a compound and inversely proportional to water solubility of a compound. The larger the
value of Henry's law constant for a chemical, the greater is the tendency of the
constituent to volatilize from water surrounding soil particles into soil pore spaces or into
air above the ground surface. Henry's law constant is strongly influenced by
temperature; for example, for many volatile hydrocarbons, Henry's  law constant increases
about threefold for every 10° C temperature rise.

Application:  Compounds with higher Henry's law constants (greater than 10"3 atm-
m /mole) are amenable  to treatment with vacuum extraction technologies.  The Henry's
law constant should also be considered in assessing potential for natural inter-media
transport of constituents from soil gas  to the air.  Henry's Law constant values for
selected contaminants are provided in  Table 3 of Appendix  1.
Hydraulic Conductivity

Description:  A measure of soil or aquifer permeability (i.e., the ease with which water
at the prevailing viscosity will flow through soil or aquifer materials.) Hydraulic
conductivity is dependent on porosity, grain size, sorting, consolidation, cementation,
fracturing, and other soil and rock factors. Units are commonly given as
centimeters/second, gallons per day/square foot, feet/day, or meters/day.  Saturated
hydraulic conductivity occurs when all of the pore  space (porosity) is filled with fluid,
generally water, and is a constant for a given system. Unsaturated hydraulic conductivity
occurs when part of the pore space is filled with air  and therefore the available cross-
sectional area available for water flow is reduced.  Consequently unsaturated hydraulic
conductivity is a function of water content and is always less than saturated  hydraulic
conductivity for the same subsurface material. Appendix 2 provides hydraulic conductivity
unit conversions.

Application:  Hydraulic conductivity is used to evaluate flow through porous media using
Darcy's Law,  Q = -KA (dh/dl), where Q is in units of volume/time, K is the hydraulic
conductivity (length/time), A is the cross-sectional area for flow (distance2), and  (dh/dl)
is the hydraulic gradient. The negative sign indicates that  flow is in the direction  of
decreasing gradient (decreasing hydraulic head). An aquifer or unsaturated  soil of high
conductivity will allow greater fluid flow  (water or air ) and also greater free product
recovery than  a subsurface characterized by low hydraulic conductivity for a given
hydraulic gradient. However, contaminant transport and spreading will also be
correspondingly greater with greater hydraulic conductivity unless the hydraulic gradient
is zero. A value for hydraulic conductivity lower than 10"6 cm/sec will limit the efficacy
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of pump and treat for remediation; a value lower than 10"5 cm/sec will limit the efficacy
of soil flushing and in situ bioremediation.


                  jjangg of Typical Values of Hydraulic Conductivity

              Geologic Formation                                cm/s

             Unconsolidated Deposits:
                  Gravel                                      10'1  - 102
                  Sand                                        lO'5  - 1
                  Silt                                          10"7  - ID'3
                  Clay                                        10"10 - lO'7
             Rocks:
                  Permeable basalt                             10"  - 1
                  Karst limestone                              10"4  - 1
                  Sandstone                                   10"8  - W4
                  Limestone, dolomite                          10"  -  10
                  Shale                                        10"11   10"7
                  Fractured igneous and
                   metamorphic rocks                          10"6  - 10"2
                  Unfractured igneous and
                   metamorphic rocks                          10"12   10"8


Hydraulic Gradient

Description:  Change in static head per unit distance in a given direction.  The hydraulic
gradient defines direction of flow and may be expressed on maps of water level
measurements taken at a facility. Ground water flow velocity is directly related to
hydraulic gradient. Both vertical and horizontal gradients should be characterized.

Application:  Hydraulic gradient information is used  in conjunction with hydraulic
conductivity to determine the rate at which water will flow through an aquifer. Flow rate
may be increased by increasing the hydraulic gradient to move more water through the
subsurface for pump and treat or soil washing  remediations, or for application of
nutrients for bioremediation. Conversely, flow may be decreased  by decreasing the
hydraulic gradient to move water more slowly for containment or  to reduce the further
spread of contamination on-site and off-site.
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Hydrolysis

Description:  The chemical reaction of a compound with water or an aqueous solution to
form a new compound containing a carbon-oxygen bond.

Application:  Hydrolysis is a significant environmental degradation process for many
organic chemicals and is dependent upon acidity and  hydroxyl ion concentrations. For
example, hydrolysis of TCE-epoxide is an important environmental reaction in the
chemical degradation of TCE. This process should be considered in designing
remediation as well as sampling and analysis programs. The following table provides
examples of hydrolysis rates for specific compound types:
                 Range of Hydrolysis Values for Selected Compounds

       Organic Compound Type                    Half-Life(average)

             Alkyl and benzyl halides                       2 hours
             Epoxides                                     1 day
             Aliphatic acid esters                           6 days
             Alkyl halides                                  9 days
             Phosphoric acid/thiophosphoric acid esters      100 days
             Carbamates                                   4 years
             Aromatic acid esters                          15 years
             Polyhalomethanes                            100 years
             Phosphoric acid esters/Dialkylphosphonates     220 years
             Amides                                      500 years
In situ methods

Description: Methods or technologies that can be used to remediate or analyze
contamination directly in the environmental media where the contamination is located.
Contaminated material is not removed but is  treated or analyzed in-place.

Application:  Chemical, physical, and biological processes applied for in situ treatment
have been described and documented, including applications and limitations, in the
following U.S. EPA publications: (1) Review  of In-Place Treatment Technologies for
Contaminated Surface Soils,  Volumes 1 and 2, EPA-540/2-84-003a,b; (2) Handbook on
In Situ Treatment of Hazardous Waste Contaminated Soils, EPA/540/2-90-002; and (3)
Bioremediation of Contaminated Surface Soils, EPA/600/9-89/073.
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Infiltration

Description:  The first of three stages of liquid transmission in the vadose zone; the
second is identified as percolation; the third is recharge.  Infiltration is the flow of a fluid
(usually water, which possibly may contain contaminants) across the land surface into a
subsurface area. Infiltration usually is the downward flow of fluids through soil layers or
movement of ground water into another subsurface area. Infiltration losses in canals and
impoundments are generally described as "seepage" losses. Infiltration rates decrease
with time after the onset of rainfall and ultimately reaches an approximately  constant
rate.  Factors affecting infiltration of water and contaminants include soil  texture, soil
structure, initial  water content, presence of shallow impeding layers or water  tables,
water temperature, entrapped and confined air, and biological activity. Typical values
are, for clay, less than 0.1 inch/hour, and for sand, more than 2.0 inches/hour.

Application:  Infiltration values are used to estimate recharge and contaminant loading
to aquifers, and  therefore are used in fate and transport analyses, assessment of spread
of contamination, assessment of remediation  alternatives, and exposure assessments.
One form of quantitation of infiltration is given by the Green and Ampt equation:
                            Vi=

where V; is the infiltration rate, K is the hydraulic conductivity of the wetted zone, t^ is the
depth of water above the soil, hcr is the critical pressure head for soil wetting, and Lf is the
depth of the wetting front. A simpler relationship using infiltration is the calculation of pore
velocity through the vadose zone, assuming long-term (greater than one month) infiltration
data: v = I/O, where v is the pore velocity, I is the infiltration rate, and O is the average
long-term steady state soil moisture content.  As an example, if the long-term intake  rate
of a pond is two feet per day, and the water content of the vadose zone is 25 percent, the
average velocity would be 2/0.25  = 8 feet per day.  If the  water table is 100 feet below
ground surface, the travel time of fluids to the water table would be 100/8 = 12.5 days.
Interferences

Description:   Undesired responses of analytical equipment caused by a substance in the
sample matrix other than the one being measured.

Application:   Interferences may result in analytical results that are either too high or too
low. Interferences may be evaluated by spiking the sample matrix with known chemicals
and measuring the efficiency of recovery from the matrix.  Trapping of the compound in the
matrix results in  low percent recovery,  and are referred to as  negative  interference.
Recovery of more than 100% of the spike implies that the matrix contains some compound
which is "perceived"  incorrectly as the analyte. These interferences are known as positive.
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Inversions [temperature, air]

Description:  Usually refers to temperature inversions, an atmospheric condition caused
when a layer of warm air prevents mixing or escape of cooler air trapped beneath it.

Application:  Inversions trap contaminants that might otherwise be dispersed, resulting in
higher environmental concentrations and exposures to receptors. Thermal inversions often
occur in situations where cities are located in geographic settings such as valleys or bowls
where air  masses can be trapped. Air quality at sites located in such areas may be adversely
impacted  by inversions, and Corrective Action Plans  should take this into consideration.
Ion exchange capacity - See Cation exchange capacity (CEC).
Isopleth plots

Description:   Maps consisting of lines  depicting points of equal value (for example,
elevation, contaminant concentrations or any quantity that can be numerically measured and
geographically plotted). Isopleths often represent an approximation of contamination, not
the actual distribution of a substance. Isopleths may overlook major heterogeneities in
contaminant distribution, e.g., if a sample is from a clay lens in a sandy aquifer, the resulting
isopleth may be inaccurate. The method used to create isopleth plots (Kriging, triangulation,
"professional judgement", variogram analysis, etc.) should be documented.

Application:  Isopleth plots can be used to assist in site characterization as well as to assess
rate and extent of remediation in a 3-dimensional framework.  Plots can be used to show
3-dimensional patterns of decrease in contamination concentration in a soil profile as a
result of treatment.
Kinematic viscosity

Description:  Ratio  of dynamic viscosity to density. Kinematic viscosity of a compound
provides an indication of the ease with which the compound (in its pure form) will percolate
through the subsurface.  The lower the kinematic viscosity of a compound, the greater will
be its tendency to migrate in a downward direction.

Application:  Kinematic viscosity is of particular importance with regard to the movement
of DNAPLs in aquifers.  The lower the  kinematic viscosity of a DNAPL, the greater will be
the ease with which the DNAPL will move downward and penetrate the finer grained layers
in the subsurface. The  kinematic viscosity of water is approximately 1.0 centistokes (cs).
Mobility can be rated as high for  compounds with values  less than  0.4 cs, moderate  for
compounds with values between 0.4 and 0.8 cs, and low for compounds with values greater


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than 0.8 cs.  Values for this parameter for selected contaminants are provided in Table 3
of Appendix 1.
Laboratory scale - see Treatability Studies
Leachability

Description:  Dissolution of soluble constituents from waste, soil, rocks, or other media by
the action of aqueous solutions.  This factor aids in evaluating potential for migration of
contaminants from a contaminated media, such as a landfill.

Application: Leachability of a compound is directly related to water solubility which governs
extent to which a compound will partition in the aqueous phase. Water solubility has been
ranked high for chemicals present at concentrations greater than 1,000 mg/L, moderate for
chemicals present at  concentrations between  1 and 1,000  mg/1, and  low for chemicals
present at concentration less than  1  mg/L. Leachability can also be evaluated using the
relationship between concentration of a chemical in soil and in water when the system is at
equilibrium: Kd  =  CS/CW (See Adsorption).
Light non-aqueous phase liquids (LNAPL)

Description: A liquid that has a density less than water and therefore floats above the water
table.  Examples include automotive and aviation gasolines, jet fuels, most oils, kerosene,
and working solutions such as carrier oils used in wood preservation (See Density). Presence
of an LNAPL complicates  site  characterization and generally decreases efficiency of pump
and treat systems in  recovering subsurface contamination. An LNAPL moves in response
to pressure gradients and  gravity. LNAPLs generally flow in  the direction of decreasing
hydraulic gradient of the water table.  LNAPLs can become trapped in pore spaces by
capillary forces and become difficult to remove through free product recovery pumping. The
residual saturation in pore  spaces can be a significant source of contamination to air, water,
and contiguous soil in the subsurface. Residual saturation may be created with fluctuations
in ground water depth as well as with drawdown cones created in the process of free product
removal using pumping systems.  Pump and treat applications may  be severely limited by
the amount and type of residual saturation.

Application: Data requirements  for site characterization of  LNAPLs in the subsurface
include: (1) specific  gravity (density),  (2) viscosity, (3) residual saturation, (4)  relative
permeability/saturation/capillary pressure relationships, and  (5) LNAPL thickness  and
distribution. LNAPLs  that comprise a  free phase that  floats  on the surface of the water
table  may be stabilized through  product recovery using a pumping system, if the  site is
sufficiently permeable  to  allow flow  and  extraction  of LNAPLs.   Physical recovery


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techniques for removing LNAPLs include: (1) single pump systems producing a mixture of
hydrocarbon and water that must be separated, (2) two-pump, two-well systems utilizing one
pump to produce a water table gradient and a second well to recover floating product; or
(3) single wells with two pumps in which a lower pump produces a gradient and an upper
pump collects free product. All pumping systems create a cone of depression, or drawdown
cone, which may introduce LNAPL into subsurface material previously uncontaminated and
create  residual saturation.  Stabilization methods for LNAPLs in the subsurface should
account for  potential  smearing and avoid  or minimize moving  the  product  into
uncontaminated areas where more product can be held at residual saturation.
Lithology

Description: Description of the composition of unconsolidated deposits or rocks including
physical  and chemical characteristics  such  as color,  mineralogic composition, hardness,
packing,  and grain size.

Application:  Lithology should be considered in the evaluation of potential contaminant
migration pathways. Mineralogy and grain size may qualitatively indicate chemical reaction
potential; for example, clays have high reaction potential while sands have little chemical
reaction  potential.
Mass balance

Description:  An approach to  evaluation of fate  and transport of contaminants in an
environmental system that  involves accounting for  distribution, transport, and biotic and
abiotic reactions of a chemical in subsurface fluid  and solid phases.  The tendency  of a
chemical to  be distributed among different  compartments  in  the  subsurface  can be
quantified through determination of partition coefficients between soil and water (K
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Application:  A mass balance approach may  be utilized  for integrating data collection
activities in order to simultaneously address site characterization and remediation technology
selection.   The information obtained  in a mass  balance approach is used specifically to
address the following  issues:  (1) characterization,  (2) assessment of the problem, (3)
treatment train  selection, and (4) monitoring.  Characterization  of  the waste/soil/site
addresses the question "Where is the contamination and in what form(s) does it exist?" The
second step,  assessment  of  the problem, utilizes chemical mass balance information to
address the question "Where is  the contamination going under the influence of natural
processes?" The problem can be defined in the context of mobility versus degradation for
chemicals.   Using mathematical models  that  incorporate mass balance  information,
chemicals can be ranked in order of their relative tendencies to leach,  volatilize, degrade,
and to remain in-place under site-specific conditions. Containment and/or treatment options
can  then  be selected  that  are  chemical-specific and that address specific escape and
attenuation pathways (third step). Treatment trains can be selected to address specific waste
phases at specific times during remediation (volatile, leachate, solid phase, pure product),
with the selection dependent upon results of a mass balance evaluation through  time to
identify the fate of each waste phase. Finally monitoring  programs can be  designed for
specific chemicals in specific phases in the subsurface at specific times  (fourth step). Thus
the  chemical mass balance approach assists  in collecting  specific information that is
transferrable among all four issues and also addresses the technical issues of subsurface
remediation within the context of regulatory goals.
Material and energy balance

Description:  An accounting of all the mass and energy entering a reaction or system and
all  those that leave  it in  a given time period.  This  description is appropriate for one
treatment process or one technology.

Application:  For example, a  material balance for a hazardous  waste  incinerator would
involve the input of fuel,  waste, and  air;  the output of combustion  products and any
unconsumed  compounds,  plus the  accumulation and removal  of deposits (ash) in the
incinerator. The evaluation of a material and energy balance are essential in assessing
treatment processes and in residuals management.
Maximum Contaminant Level (MCL)

Description: Under Section 141 of the Safe Drinking Water Act, as amended, the maximum
permissible level of a contaminant in water delivered to any user of a public water system.
MCLs reflect  health factors and  the  technical and economic feasibility  of recovering
contaminants from the water supply.
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Application:  For RCRA corrective action, MCLs are often used as cleanup standards.
Values for this parameter for selected contaminants are provided in Table 3 of Appendix
1.
Melting point

Description:  The temperature at which a solid begins to melt and change state to liquid.
An indication of the physical state of a pure compound at field temperatures.

Application:  Compounds with melting points above 30° C, for example, would be expected
to be relatively immobile in pure form. Such compounds would be of primary concern when
in the dissolved phase, either in water or another solvent. Compounds with melting points
lower than 30° C may be  present as  mobile  non-aqueous phase liquids (NAPLs) in
subsurface environments. Values for this parameter for selected contaminants are provided
in Table 3 of Appendix 1.
Method detection limit

Description: Minimum concentration of an analyte that can be measured by a particular
analytical method and reported with 99 percent statistical confidence. This is determined
from analysis of a sample in a given matrix. Detection limits should be specified at or below
levels of concern.

Application:  Method detection limits provide a lower boundary  for measurement of the
clean-up level for a particular process or technology.
Mineral content

Description:  The level of naturally occurring inorganic materials in soils, rocks, aquifer
sediments, ground water, or wastes.

Application: Information concerning mineral content is important in assessing the reactivity
of soil or geologic materials with contaminants and the migration of contaminants through
the materials. For example, high levels of naturally occurring dissolved iron may be oxidized
to insoluble iron near recovery or injection wells, and  thus be responsible for reducing water
transmitting properties of an aquifer. Also, high concentrations of soluble iron in water
pumped to the surface for further treatment  (pump and  treat) may clog above ground
treatment systems that use air stripping or carbon  adsorption.  Mineral content of the
subsurface also indicates relative chemical reaction (including adsorption and chemical
degradation) potential; for example, clay minerals  are more chemically reactive than silt and
sandy minerals.


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Moisture content [of soil]

Description: Water lost from a soil upon drying to a constant mass at 105- C, expressed
either as mass of water per unit mass of dry soil or as the volume  of water per unit bulk
volume  of soil.

Application: Knowledge of the moisture content of a soil provides information concerning
the amount of water present for biological activity, amount of pore  space occupied by soil
air, and amount of water available to act as a solvent for contaminants and nutrients. The
amount of soil water  influences  soil  temperature,  and  is critical  for biodegradation of
contaminants.
Octanol/water partition coefficient

Description: Measure of the extent to which a chemical partitions between an aqueous
phase and an  organic phase (octanol).  Kow is the ratio of concentration of a chemical in
octanol to concentration of the chemical in water.

Application: This parameter can be used to predict extent of sorption of organic chemicals
onto soils.  Kow can also be used  as a basis for estimating relative bioconcentration factors
(see Bioconcentration factor).  In transport models, Kow is frequently converted to K^ (see
Organic carbon adsorption  coefficient), a parameter that takes into account the organic
content of the soil.  The higher  the value of Kow (or K^),  the greater  the tendency of a
constituent to  adsorb to soils containing appreciable organic carbon. Kow values can also
be used to evaluate efficacy of remediation  technologies.  For example, pump and treat
technology is best suited for managing chemicals with log Kow values less than 3.5; pulsed
pumping is appropriate for chemicals  with  log Kow values between 2.5 and 4.5; in situ
vitrification is  appropriate for  chemicals with log Kow values greater than 4.5.  Values for
this parameter for selected contaminants are provided in Table 3 of Appendix 1.
Organic carbon adsorption coefficient (K^)

Description: Ratio of the amount of constituent adsorbed per unit weight of organic carbon
in the soil or sediment  to the concentration  of the constituent  in aqueous solution at
equilibrium.  The tendency of a  constituent to be adsorbed  to soil is dependent on its
properties  and on the organic carbon content of soil  or sediment.  Koc  can be used to
determine the partitioning of a constituent between the water column and sediment. When
constituents have a high k^, they have a tendency to partition  to the soil or sediment. K^
is similar to Kn
             vow
Application:  Because K^ is similar to Kow, refer to the discussion under Octanol/water
partition coefficient.  In addition, some specific guidance for K^ values can be given for
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specific remediation technologies.  For example, pump and treat technology is best suited
for managing chemicals with log K^ values less than 3.0; pulsed pumping is appropriate for
chemicals with log K^ values between 2.0 and 4.0; in situ vitrification is appropriate for
chemicals with log  K^ values greater than 4.0.  Values for this  parameter for selected
contaminants are provided in Table 3 of Appendix 1.
Organic carbon content

Description:  Percentage, on a dry weight basis, of a soil or sediment that is composed of
organic carbon. Organic carbon, such as humic acids, is usually the result of decomposition
of plant and animal matter that occurs predominantly in the top layer of soil.

Application:  Information concerning organic carbon content is important  in determining
partitioning of contaminants between the soil and leachate, or into runoff phases of soil or
sediments. The organic content of upper soil layers typically ranges from 0.1 to 5 percent,
with most top soils in the range of 1 to 5 percent.  Natural soil organic content may be
difficult to measure in areas of gross organic contamination, such as oily sediment. (See
Octanol/water partition coefficient, and Organic carbon adsorption  coefficient.)
Organic carbon, total (TOC)

Description:  Total amount of organic carbon present, expressed on a dry weight basis, in
a solid or liquid.  This carbon is  derived from decomposition of biotic material or the
introduction of man-made chemicals. TOC is generally expressed as mg/L when measured
in water and mg/kg in soil. Natural waters usually contain TOC less than 5 mg/L; greater
values indicate organic contamination.

Application: TOC is used as a rapid estimate of organic contamination.  TOC is not specific
to a given contaminant or even to specific classes or organics.  TOC measurements have
little use if a release is primarily due to inorganic wastes. TOC is a ground-water indicator
parameter in 40 CFR 264 and 265 ground-water monitoring.
Particle size distribution

Description: The various size fractions into which a soil sample separates, often expressed
as mass percentages. Soil separates, as defined by the Soil Conservation Survey of the U.S.
Department of Agriculture, include mineral particles less than 2 mm in diameter, and are
divided into the following size categories: sand, 2.0 to 0.05 mm; silt 0.05 to 0.002 mm; and
clay, less than 0.002 mm.
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Application: Particle size distributions are used to describe soil texture (See Soil texture).
The texture of a soil affects its porosity, air and water permeability, infiltration rate, and
sorptive capacity.
Pedology

Description: The study of soil; including origin, description, and classification.

Application:  Pedology provides a general understanding of soils as they occur in nature.


Perched zone of saturation

Description:  A discrete pocket or lens  of unconfined  ground water separated from  an
underlying aquifer by an unsaturated zone; also known as a perched aquifer. Perched ground
water may be either permanent or temporary. Permanent perched ground water occurs
where recharge is frequent enough to maintain a saturated zone above the perching bed.
Temporary perched ground water occurs where intermittent recharge is not frequent enough
to prevent the perched water from disappearing from time to time as a result of drainage
over the edge of or through the perching bed.

Application:   Identification of perched  zones of  saturation is  essential for defining
contaminant migration pathways and  monitoring  for pockets of contamination.  Perched
zones of saturation  may be the  source of contamination  of deeper ground water. Perched
zones of saturation  may be located using a neutron moisture logger.


Permeability

Description:  Capacity of porous rock,  sediment, or soil to transmit a fluid, usually water or
air.  (See  Hydraulic conductivity).

Application:   Permeability is  often  used interchangeably  with  hydraulic conductivity.
Permeability rates as given below are often used to  determine infiltration  and long-term
intake rates as described under the topic of Infiltration. Units for permeability are identical
to those used for hydraulic conductivity (See Hydraulic conductivity). The following table
gives some examples:
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                   Soil Conservation Service Soil Permeability Rates

                   Descriptor                       Rate (inches/hour)
                very slow                              less than 0.06
                slow                                   0.06 to 0.2
                moderately slow                        0.2 to 0.63
                moderate                              0.63 to 2.0
                moderately rapid                       2.0 to 6.3
                rapid                                  6.3 to 20.0
                very rapid                             greater than 20
pH
Description:     An expression of concentration of hydrogen ions  (H+) in an  aqueous
solution. The pH scale is based on disassociation of water into hydrogen and hydroxyl ions.
The term "pH" is derived from the phrase "power of hydrogen ion concentration", which
represents the value of the exponent of H+ concentration. The scale is logarithmic and has
a range from 0 to 14 units.  A pH value of 7 is considered neutral  and represents equal
concentrations of H+ and OH" ions at 1 x 10"7 mole/liter. Values below 7 indicate higher
concentrations of H+ and  are considered to be  acid.  Values  above 7  indicate lower
concentrations, and  are considered to be basic.

Application:   pH plays a vital role in chemical and biological reactions; and can be a major
factor in  determining such things as reaction rate, solubility of contaminants in water,
species of metal, ionization potential, precipitation/dissolution of minerals, composition and
activity of microbial communities, metal corrosion,  and toxicity of contaminants,  see
Alkalinity, Redox Potential, Speciation, etc.
Photolysis

Description:  Degradation of a chemical caused by direct absorption of solar energy (direct
photolysis) or by transfer of energy from other substances that absorb solar energy (indirect
photolysis).  Photolysis  also  includes artificially induced processes such as  ultraviolet
oxidation in the treatment of ground water.  Photolysis  potential should  be considered in
designing sampling and analysis programs.

Application:    Photolysis  is  an important  degradation mechanism for photoreactive
compounds in the air, shallow surface water, and on soil surfaces; it is not an attenuation
mechanism below the soil surface  or at depth in surface water. The rate and extent of
photolysis  may be  measured in order to assess whether photolysis is an important  fate
mechanism and whether the reaction may be utilized  in a remediation  treatment train.
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Photolysis rate (expressed in terms of half-life values) are given for several chemicals in the
table below.
                                   Photolysis rate
                   Substance                            Half-Life

                 Fluoranthene                         21 hours
                     Sevin                             H days
                   p  Cresol                           35 days
Physiography

Description: Physical geography; surface features and landforms of the earth (or the area
of interest), see Topographic map.

Application: The physiography of a site affects such processes as  surface runoff, erosion,
infiltration, soil slippage, and susceptibility to flooding.
 Piezometer

 Description: A tube or pipe, open to the atmosphere at the top and to water at the bottom,
 and sealed along its length, used to measure the hydraulic head in a geologic unit.

 Application:  Data derived from piezometers can be used in determining elevation of the
 potentiometric surface of an aquifer as well as determining horizontal and vertical ground-
 water flow directions. Piezometric data can also be used to calculate the hydraulic gradient,
 which can be used in  Darcy's law to  calculate  the rate of transport of water through the
 saturated zone at a site, as well as changes  in transport rate as a result of ground water
 fluctuations. For example, if the saturated  hydraulic conductivity (K) is 1CT4 cm/sec, and the
 hydraulic gradient (H/L)  is calculated using piezometric data [elevation  in one well is
 measured at 100 feet above sea level  and  in a second well at 70 feet above  sea level), and
 the wells are located at a distance of 200 feet apart, then the  hydraulic gradient is (100-
 70)/200 = 0.15 ft/ft],  and the Darcy  velocity through the section is V - K (H/L) or lO^4
 (0.15)  = 0.15 x 10"4  cm/sec.  Determination of transport rate  is an important part of
 generating a chemical mass balance at  a site for  characterization, problem  definition,
 treatment train selection, and monitoring, as described under Mass balance.
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Pilot scale -  see Treatability Study
Plumes [immiscible or dissolved]

Description:  An area of contaminated water (or pure contaminant) originating from a
specific source. Ground-water plumes are influenced by such factors as local ground-water
flow patterns and density of contaminant(s).  Surface-water plumes are influenced by water
current and density of the contaminant.  An immiscible plume occurs where the contaminant
is either more dense or lighter than water (i.e., the contaminant is a NAPL), and hence is
found below or on top of the water, but  not mingled  with the water layer.  A dissolved
plume occurs where the  contaminant is  soluble in water.  Dissolved plumes are often
associated with immiscible plumes.

Application:    Plume   delineation  in three  dimensions  is  essential  as part  of  site
characterization activities. A chemical mass balance approach may be used  (See Mass
balance).
Porosity

Description:  Percentage of void or pore space within a rock or soil/sediment. Porosity may
be  expressed as a  decimal fraction  or  as  a percentage.   Due to processes such  as
cementation, effective porosity is a more accurate measure of water available in a formation.
Porosity and soil texture are used to assist in evaluating hydraulic conductivity. With respect
to the movement of a fluid, only the system of interconnected pore space is significant. In
general, the  greater the porosity,  the  more readily fluids may  flow through  the soil. An
exception is a clayey soil, which usually tightly holds fluids by capillary forces.

Application:  Porosity is used in the equation that describes the  relative velocities of water
and a chemical in the subsurface, i.e.,  the retardation of a chemical in the subsurface:  R
= 1
+ r Kd/n (See Adsorption).
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                        Range of Values of Absolute Porosity

                      Geologic Material                 Percent

                   Unconsolidated deposits

                   Gravel                                 25 - 40
                   Sand                                  25 - 50
                   Silt                                    35 - 50
                   Clay                                   40 - 70
                   Rocks
                   Fractured basalt                         5-50
                   Karst limestone                          5 - 50
                   Sandstone                               5-30
                   Limestone, dolomite                     0-20
                   Shale                                   0  10
                   Fractured crystalline rock                 0 - 10
                   Dense crystalline rock                    0   5

      Effective Porosity  The amount of  interconnected pore  space available for fluid
      transmission.   It is  expressed  as  a  percentage  of the total volume occupied  by
      interconnected pore space.  This information aids in evaluating the rate at which
      ground water and contaminants can migrate through different geologic units.


Potentiometric (surface) map

Description:  A contour map of ground-water pressure head for a given water bearing zone.
It represents the levels to which water will rise in wells cased to and screened in that water
bearing zone.

Application:   Ground-water flow  directions will be perpendicular to the contours and
towards areas of lower potential.  Contours that are closer  together indicate a greater
hydraulic gradient, which influences ground-water flow velocity.


Qualitative and quantitative flow sheets [for corrective measures design]

Description:  Charts or line drawings used to indicate successive  steps in a process design.
A flow sheet carries information such as temperatures, pressures, flow rates, and process
equipment at varying  points in the process.
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Application:  Flow sheets provide sufficient detail for process design and cost prediction.
Evaluation of the flow  sheets for corrective measures design is conducted to determine
whether the design will  achieve the stated objective.
Reagent

Description:  A substance used in a chemical reaction to detect, measure, examine, or
produce other substances.

Application:  These substances may be used to support laboratory analysis or treatment
processes.
Reagent quality control checks

Description:  Methods established to ensure that reagents used for analytical procedures are
of the quality required for accurate laboratory analysis.
Recharge

Description:  Addition of water into the zone of saturation; for example, a recharge area
occurs where rainwater soaks through the earth to reach an aquifer. In designing a ground-
water corrective action program, accurate estimates of recharge amounts are essential to
ensure that appropriate ground-water pumping rates achieve the desired zone of capture.
Recharge rates are equal to deep percolation rates in the  area of the ground water.

Application:  Percolation rates, and therefore recharge rates in the vicinity of the ground
water, are described by modifications of Darcy's law for saturated systems.  An approach
for estimating recharge from large spreading areas and extensive impoundments is to apply
Darcy's law (See Hydraulic conductivity).
Redox potential (Eh)

Description:   Expression  of  the  electron  density of a  system.   This is a numerical
measurement, referred to as Eh and measured in volts, of the oxidation/reduction properties
of an environment. As a system becomes more reduced, there is an increased electron
density and decreased potential. Redox potential is directly correlated with dissolved oxygen
(DO) concentrations. High DO in aqueous systems (>4  mg/L) results in high  Eh and
oxidizing conditions.  Low DO (< 1 mg/L) results in low Eh and reducing conditions.
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Application:   Eh also has a direct effect on metal speciation.  Equilibrium speciation of
some metals is dependent on the Eh and pH of a system. Eh-pH diagrams are often used
to illustrate predominant dissolved and mineral species at equilibrium.  For example, with
iron, in well-aerated soils with pH above 4, hydrous ferric oxide minerals and coatings are
considered to be the soil minerals controlling equilibrium aqueous Fe+3 concentrations. As
the system becomes more reduced (lower Eh values), Fe+2 may be expected to predominate
up to pH 8.  As oxygen becomes limited in the subsurface, a variety of anoxic oxidation
processes will follow and will be influenced by the redox potential.  Microbial metabolism
in a soil system is  accomplished by aerobic and  facultative  microorganisms at  redox
potentials ranging from about 600 to 0 millivolts, while at potentials from 0 to about -200
millivolts, obligate anaerobes are predominant. Where sulfates, nitrates, iron, manganese,
and carbonates are available, as affected by redox conditions, these electron acceptors may
influence degradation of organic  chemical contaminants.   As  redox potential decreases,
electron  acceptors will be used in the order: nitrate, ferric iron, manganese dioxide, ferric-
oxy hydroxides, sulfate, and carbonate for the degradation  of organic contaminants.
Residual saturation

Description:  Saturation below which fluid drainage will not occur (Also referred to as
irreducible saturation). Residual saturation depends mainly on two factors: (1) distribution
of soil pore sizes, and (2) type of immiscible fluid involved. Residual saturation is difficult
to estimate accurately and is subject to considerable error.  The amount of oil  normally
retained in soil is between 15 and 40 liters per cubic meter.

Application:  See LNAPLs, DNAPLs, and Density.
Samples

Description:

      "Blind" quality  control  samples   Samples submitted by  an outside source  to
      determine the quality of analyses performed by a particular  laboratory.  These
      samples may  be prepared with  an  exact  concentration  of a  constituent that is
      unknown to the laboratory. Alternatively, these samples may  be blanks or duplicates
      that are not labeled as such (the latter are also known as "blind duplicates"). These
      samples are used to determine the internal quality control of analytical  work.

      Calibration check samples - Samples of known concentrations of a substance that are
      analyzed to verify the accuracy of an instrument's readings.  The readings  can then
      be used to prepare calibration curves for further analysis of  actual samples.
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      Composite samples - Samples prepared by mixing two or more grab samples that
      typically represent an average value over a period of time or within a given area.
      Composite  samples reduce  costs of sampling  and  analyses,  but  do  not  allow
      determinations of the highest and lowest contaminant concentrations within  the
      sampling area.

      Grab samples  Discrete samples taken from one specific sampling point at a specific
      time.

      Laboratory control samples - Samples of known chemical concentration or physical
      characteristics  that are used in the laboratory to assess  analytical precision and
      accuracy.

      Matrix-spiked samples - Samples to which known amounts of certain chemicals are
      added before extraction or digestion and  analysis.  The percent recovery of each
      chemical is calculated to assess potential  effects  of the sample matrix on analyte
      recovery.

      Replicate samples - Samples that have been divided into two or more portions at
      some step in the measurement process.  A sample may be replicated in the field or
      at different points  in the analytical process.   Information derived  from replicate
      samples is  necessary to analyze quality of data.

      Sample  matrix-   Physical and  chemical  properties  that describe  a sample,  for
      example, soil, sludge, water. Knowledge of the sample matrix is necessary to devise
      proper handling and analytical procedures.  Interferences inherent in the sample
      matrix can  affect  detection limits.  For example, normal detection limits may  be
      impossible to achieve in some soils contaminated with oils.

      Surrogate  samples  -  Samples  that  are  spiked prior to  analysis  with  organic
      compounds that are not normally found in environmental samples but are similar to
      analytes of interest. Percent recoveries are calculated for each surrogate.  Surrogate
      samples are used to determine possible interferences.
SCS soil classification

Description:  Soil classification system developed by the U.S. Department of Agriculture's
(USDA) Soil Conservation Service (SCS).  The system was primarily  developed for
agricultural purposes. The system provides information on typical soil profiles (e.g., 1-foot
fine sandy loam over gravelly sand, depth to bedrock 12 feet), chemical characteristics and
ranges of permeabilities for each layer, and approximate particle size ranges. These values
are not generally accurate enough for predictive purposes, and should not be used to replace
field data. (See ASTM classification [of soil])


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Application:  Knowledge  of the classification of a soil provides information on potential
water and air permeability of soil and potential for assimilation of waste constituents in soil.
Sensitive subgroups

Description:  Environmentally sensitive groups (e.g., wetlands) or human population groups
with high sensitivity to chemical exposure (e.g., infants, children, elderly people, pregnant
women, and people with chronic illnesses). Associated land uses include schools, day care
centers, hospitals, nursing homes, and retirement communities.

Application: Information on sensitive subgroups should be collected during risk assessments.
Soil texture

Description:    Relative  proportions  of the various soil  separates (See  Particle  size
distribution) as described by classes of soil texture shown in the soil textural triangle. The
soil textural triangle for the U.S. Department of Agriculture system of soil classification is
presented in Appendix 3.

Application: Texture  of a soil affects  its porosity, air and water permeability, infiltration
rate, and sorptive capacity.
 Soil-water partition coefficient (kd)

 Description:   The  ratio  of adsorbed  contaminant concentration  to  the dissolved
 concentration at equilibrium. The  soil-water  partition coefficient is  generally  used to
 quantify soil sorption. The extent to which a constituent is absorbed depends on chemical
 properties of the constituent and of the soil (See Adsorption).

 Application: This parameter will aid in predicting contaminant migration through the soil
 matrix (See Adsorption).
Solubility [of waste]

Description: Maximum concentration at which a constituent can dissolve in water at a given
temperature. Solubility in water governs the extent to which a contaminant will partition into
the aqueous phase. The greater the water solubility of a compound, the greater will be the
tendency for that compound to migrate with the aqueous advective flow component. Water
solubility  values, in conjunction  with  vapor pressure can provide an assessment of the
potential for  volatilization (See Henry's law constant).


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Application:   Solubility is  an important function affecting the release and subsequent
migration or fate  of a constituent in the ground-water or surface-water environment.
Chemicals with higher water solubilities are more amenable to removal from the subsurface
by pump and treat technology. These same compounds, however, are more likely to migrate
through the vadose zone to ground water (See Leachability). Values for this parameter for
selected contaminants are provided in Appendix 1.
Sorption

Description:  A general term that encompasses the processes of absorption, adsorption,
desorption, and ion exchange. Sorption is a major subsurface chemical process that affects
fate  and transport of contaminants (See Absorption,  Adsorption, and  Cation  Exchange
Capacity).
Sorptive capacity

Description:  Potential for materials to chemically sorb contaminants and thereby retard
contaminant migration.  Major soil parameters that influence sorption include total organic
carbon  content and  particle size  distribution.   This  information  aids in predicting
contaminant movement through soils (See Absorption, Adsorption, and Cation Exchange
Capacity). The following table gives examples of the sorptive capacity of some geologic
materials:
                               Sorptive Capacity
Values
High
Medium
Low
Geologic Materials
Clays, organic rich sediments, silts
Sands
Limestones, dolomites, gravels, clean sands
Metamorphic and igneous rocks
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Speciation [metals]

Description:  The wide  range  of transformation processes  by which metallic chemical
compounds form and are transformed.  Speciation can occur in all environmental media.
The final form or speciation of a metal in a given environment affects its solubility, sorption
properties, and toxicological properties.  Speciation may change as a result of sampling
effects.  For example, collection of a ground-water sample may result in oxidation of the
sample, which changes speciation.

Application:  Change in chemical species may affect inter-phase transfer. For example,
mercury in the  + 2 form (Hg+2)  is soluble but  may be reduced by microorganisms to the
elemental form (Hg°), which is volatile.  Volatile forms of selenium and arsenic (AsH3) may
also be formed under reducing conditions through changes in chemical species. The selenate
form (SeO42~) will dominate under oxidizing conditions, while the selenite form (SeO32~) will
dominate  under increasingly reducing conditions. The arsenate form (AsO43~) will dominate
under oxidizing conditions while the arsenite form, which is more toxic and mobile, will form
under reducing and acidic conditions. Property  change associated with a change in  species
may be utilized in remediation strategies to remove  and recover soluble and non-volatile
metals as  volatile species.  Another application of speciation is  reduction of hexavalent
chromium (Cr+6), which exists as a highly toxic and highly mobile hydrated anion in the
subsurface, to trivalent chromium (Cr+3), which  is less toxic and exists in the  form of a
cation. The change in speciation from hexavalent to trivalent results in reduced mobility in
a subsurface environment because the soil is generally negatively charged and has  a finite
cation exchange capacity. Cyanide ion (CN~) predominates in aqueous solution only at pH
values greater than 9.  Hydrogen cyanide (HCN) predominates at pH values less  than 9.
HCN is volatile (vapor pressure of 741 mm Hg  at 25° C) and toxic, while  CN" tends to
complex with iron.   Iron  may  occur  as the  mobile ferrous  form  (Fe+2)  in reducing
conditions, and as  the  less  mobile  ferric  form  (Fe+3)  under  oxidizing  conditions.
Compounds and metals complexed to  iron may  be  removed from the  subsurface under
oxidized conditions. Conversely, compounds and metals adsorbed to iron my be increasingly
mobilized  under reduced conditions. Precipitated iron may hinder treatment processes such
as in situ bioremediation and air stripping.
Specific Conductance  See Conductivity
Specific yield

Description: Ratio of the volume of water that will drain under gravity to the total volume
of saturated material.  In an  unconfined  aquifer,  the  specific yield is  the ratio  of the
drainable volume of water due to gravity to the bulk volume of the aquifer medium (some
liquid will be  retained in the  pore spaces).  Specific yield is used only for unconfined
aquifers, as confined aquifer materials generally are not dewatered during pumping. Specific


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yields of unconfined aquifers are much higher than storativities of confined aquifers.  The
usual range of specific yield is 0.01-0.30. Specific yield is also known as effective porosity
for unconfined systems. Specific yield values may be necessary to perform complex ground-
water modeling.

Application:  Because specific  yield is also known as effective porosity,  see Porosity and
Effective Porosity.
                      Volume of Water Yielded/Volume of Rock

                 Material                                   Ratio Range
             Sedimentary
                Sandstone(fine)                                0.02 - 0.40
                Sandstone (medium)                           0.12 - 0.41
                Siltstone                                      0.01  0.33
                Sand (fine)                                    0.01 - 0.46
                Sand (medium)                                0.16 - 0.46
                Sand (coarse)                                 0.18 - 0.43
                Gravel (fine)                                  0.13 - 0.40
                Gravel (medium)                              0.17 - 0.44
                Gravel (coarse)                                0.13 - 0.25
                Silt                                           0.18 - 0.39
                Clay                                          0.01 - 0.18
                Limestone                                    0.00 - 0.36
             Wind-Laid
                Loess                                         0.14 - 0.22
                Eolian Sand                                   0.32 - 0.47
                Tuff                                          0.02 - 0.47
             Metamorphic Rock
                Schist                                         0.22 - 0.33
Stereographic analysis

Description:  Three-dimensional visualization of surface features created by viewing an
overlapping pair of photographs taken at different angles through a binocular optical
instrument (i.e., a stereoscope)

Application: This analysis may be used to identify potential contaminant pathways,
potential  sites for treatment, storage,  or  disposal facilities, or topographic factors that
influence  ground-water systems,
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Storativity

Description: The volume of water that an aquifer releases from or takes into storage per
unit surface area of aquifer per unit change in the component of pressure head normal to
that  surface  (Also  referred to as storage coefficient). The storage coefficient for  an
unconfined aquifer  corresponds to its specific yield.  In confined  aquifers, if the aquifer
remains saturated, changes in pressure produce only small  changes in storage volume.

Application:  Storativity values may be used to determine how rapidly the flow system will
respond to pumping. This factor is important for pump and  treat systems where pulsed
pumping is used. Storativity can be used to help determine the cycle duration of pumping.
Stratigraphy

Description: Description of original rock succession and age of rock layers ("strata"), as well
as their formation, distribution, composition, fossil content, and geophysical and geochemical
properties. Descriptors include strike (the direction taken by a structural surface) and dip
(measured perpendicular to the strike; the angle that a geological  feature makes with the
horizontal).  Stratigraphy also encompasses unconsolidated materials, such as soils.

Application:  Knowledge of stratigraphic features is critical to the design, monitoring, and
corrective action programs, as these features will largely influence contaminant migration
pathways. For example, stratigraphic information will aid in determining potential fracture
flow pathways, estimating extent of flow, and defining the hydrogeologic framework.
Temporal changes

Description:   Changes in the value of measured  parameters over time.  In hydraulic
gradients, those variations due to seasonal or daily influences, river, estuarine, or marine
tidal movement, and human activity (for example, ground-water pumping, changes in land
use, and  waste disposal practices).

Application: This factor is critical for evaluating surface-water and ground-water pathways
and receptors. For example, temporal changes in ground water levels may cause smearing
of LNAPLs as the level of ground water decreases and increases, resulting in the change of
free product to residual  saturation  in the subsurface.  Remediation using LNAPL free
product recovery pumps will be based upon location and depth of the LNAPL with respect
to the water table.  Therefore changes in water table elevation must be monitored through
time to accurately locate and remove free product occurring on top of the water table. For
treatment of the residual  saturation  of LNAPLs, see LNAPLs and  Residual saturation.
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Total Dissolved Solids (TDS)

Description:  The total amount of solids that remain when a water sample is evaporated to
dryness.  TDS includes carbonates, sulfates, chlorides, nitrates, phosphates, metallic ions,
iron, calcium, potassium, and others that pass through a fine, glass-fiber filter (usually 0.45
micron). TDS  is a basic measure of water quality.

Application:  As  TDS increases, conductivity of the water also generally increases. See
Conductivity [of water].
                            Total Dissolved Solids

                Class                                    Values (mg/L)

             Drinking water                                    <  500
             Fresh water                                     0   1,000
             Brackish                                    1,000 - 10,000
             Saline                                    10,000 -  100,000


Total Suspended Solids (TSS)

Description:  Undissolved organic and inorganic particulate matter in water that contributes
to turbidity.  TSS is measured as the dehydrated weight of organic and inorganic solids
retained on a fine, glass-fiber filter (usually 0.45 micron).

Application:  TSS is an important parameter for above ground treatment units utilized as
part of pump and treat remediation, including activated carbon, air stripping, ion exchange,
and reverse  osmosis  treatment units. TSS  will physically clog these units and decrease
efficiency and performance time. TSS should be evaluated for  potential impacts on above-
ground treatment  processes.


Transects

Description:  A type of vertical profile that represents data along a plane.

Application:  For soil and ground-water data, several cores or monitoring wells are selected
that are in approximately a straight line through the areas of interest. The information is
then graphically displayed as a cross section.
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Transmissivity

Description:   Transmissivity is  defined as the hydraulic  conductivity multiplied by the
thickness  of a confined  aquifer.  In an unconfined aquifer, transmissivity is not as well
defined as in a confined  aquifer. Transmissivity in an unconfined aquifer is defined as the
hydraulic  conductivity multiplied by saturated thickness of the aquifer.  Transmissivities
greater than 0.015 meter2/second represent aquifers suitable for use as water wells.

Application:  Subsurface environments with high transmissivities are appropriate for pump
and treat  technology, vacuum extraction, soil flushing, and bioremediation, which rely on
delivery and recovery of fluids or air for accomplishing subsurface remediation.


Treatability studies [laboratory, bench, pilot, field]

Description:   An organized series of experiments designed to determine the best approach
for treating wastes. Extent and scope  of  treatability studies range  from laboratory-scale
"proof-of-concept" efforts to field-scale demonstrations.  In general, treatability studies start
at the laboratory scale and proceed through intermediate steps to pilot-scale or field-scale
studies.   As this process continues,  information that  is generated answers increasingly
specific questions  concerning feasibility, design, cost,  and performance.  The cost  and
complexity of treatability studies therefore increases with scale.

              Laboratory-scale
              Small-scale (jar, beaker, column) screening studies performed to  determine
              if specific wastes can be treated by specific processes or approaches.  Often
              "proof-of-concept",  these  studies are  used for  preliminary  screening of
              treatment  alternatives.   Laboratory  studies usually generate  qualitative
              information concerning general validity of a treatment approach. They do not
              provide  quantitative information concerning cost, design,  or  performance.
              Laboratory-scale studies  involve small  volumes or masses  of  test material,
              utilize primarily batch tests, and can screen a large number  of parameters to
              identify those critical for  further testing.

              Bench-scale
              Intermediate  scale studies  (often performed in a laboratory) which are
              designed to provide quantitative information  to evaluate  performance of a of
              remediation technology. Bench-scale studies generally are intended to answer
              specific design,  operations, and cost questions, and are  more  detailed than
              laboratory studies. They  can be used to obtain a mass balance of chemicals
              within a system to determine  fate of the chemicals, including  interphase
              transfer and/or reaction  (for example,  volatilization, sorption,  desorption,
              biodegradation, chemical degradation, etc.),  in order to  evaluate technology
              performance.  The equipment and experiments are designed to simulate basic


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             operation of the treatment process.  The mass or volume of materials tested
             is greater than laboratory-scale experiments, and tests can be either batch or
             continuous.
             Pilot-scale
             Large-scale experiments designed to provide detailed, quantitative, cost and
             design data to optimize performance of a technology under anticipated field
             conditions.   Pilot-scale  experimental  and  equipment  designs  simulate
             operational configurations as close as possible to the anticipated full-scale
             systems.  The mass or volume of tested waste is much larger than laboratory
             or bench-scale studies. Pilot-scale study designs usually build on results from
             laboratory and bench-scale  studies, and are generally  more complex and
             costly.
             Field-scale
             Field demonstrations of treatment technology  developed from treatability
             studies.  Field demonstrations  are  intended to monitor  performance  of
             treatment systems under real world  conditions at approximately full scale.
             Field studies are designed to monitor performance and identify problems not
             encountered at less than full scale operations.
Treatment train

Description:  A combination of treatment technologies that are used at one time or that are
used sequentially at a site in order to match a specific technology to a specific contaminated
phase. A treatment train is selected after a site characterization is conducted to define the
problem at a site with regard to which phases  are contaminated and what is the potential
or actual exposure pathway for each phase.  Treatment trains are then selected to control
specific chemicals in specific phases, and therefore can be chemical-and-phase-specific.

Application:  For example, a treatment train for creosote contaminated soil and aquifer
material may involve: (1) product removal using a pumping system, (2) flushing with water
and/or surfactant solution using pump and treat technology, and (3) in situ biodegradation
of trapped residual saturation. Another example may include product removal of LNAPL,
followed by vacuum extraction of volatile materials, followed by biodegradation of residual
saturation and of sorbed chemicals.
                                         45

-------
Vapor pressure

Description:  The pressure  of vapor in equilibrium with a pure liquid or solid.  Vapor
pressure is a function of the  chemical of interest and temperature.  Units of measurement
are generally expressed in millimeters of mercury (mm Hg). For comparative purposes, the
vapor pressure of water at 20° C is 17.5 mm Hg.  Constituents with high vapor pressures are
more likely to be released  in the gaseous form than  those  with  low vapor pressures,
depending on other factors such as relative solubility and concentration.  For example, at
high concentrations, releases can occur even though the vapor pressure of a constituents is
relatively  low. This factor is important in evaluating the potential for contaminants to be
released to moist air as vapor, e.g., when excavating soils or extracting  ground water for
subsequent treatment (See Henry's  Law Constant). Within a  mixture of chemicals in a
NAPL,  chemicals will volatilize according to Raoult's  law, i.e., volatilization  will be a
function of the mole fraction of a chemical as well as the vapor pressure of the chemical.
Values  of vapor pressure for selected contaminants are provided in Table 3 of Appendix 1.

Application:  Vapor pressure values  for chlorinated hydrocarbons generally increase with
decreasing chlorine  content. In situ steam stripping facilitates the  removal of residual
organics with vapor pressure values between  10"3  and  10° mm  Hg, such  as many NAPLs,
from the vadose zone.
Vertical flow rate

Description:  The rate of vertical travel of water and contaminants from unsaturated soil to
the saturated zone as well as the upward or downward movement within the unsaturated or
saturated  zone.  The vertical flow rate is dependent on factors such as  volumetric water
content, adsorption and desorption parameters, hydraulic conductivity, and pressure head.
Information concerning vertical  flow rate aids in  identifying and predicting the  vertical
distribution of contaminants and ground-water flow patterns.

Application:   For downward  migration  through  the  vadose zone, see Infiltration  and
Recharge.  Water, and consequently chemicals, can also be advected in the upward direction
in the unsaturated zone due to evapotranspiration and changes in hydraulic gradient when
the gradient is in the upward  direction.  Calculations concerning upward  and downward
direction in the vadose zone are  based on a modified Darcy's law:

                                 J = K(q)(dH/dz),

where  J is the Darcy  flux  or  velocity, K(q)  is the hydraulic  conductivity based on  soil
moisture content, and (dH/dz)  is the hydraulic gradient that is primarily a function of matric
potential,  and not  gravity, in the  unsaturated zone. Accurate analysis of transient water
movement in the unsaturated  zone,  including upward and downward flow,  is a complex
process, is generally not influenced  by gravity, and requires a level of detail  and more


                                        46

-------
explanation than is appropriate in this document.  The reader is advised to seek texts and
articles on unsaturated flow physics or consult with someone with specific expertise in this
area.

Viscosity [of waste]

Description: The property of a fluid describing its resistance to flow. Viscosity of any bulk
liquid wastes should be determined to estimate potential mobility in soils.  A liquid with a
lower viscosity will generally travel faster than one with a high viscosity.

Application: See Dynamic Viscosity and Kinematic Viscosity.
Water quality criteria

Description: Under Section 303 of the Clean Water Act (40 CFR Part 131), water quality
criteria are comprised of numeric and narrative criteria.  Numeric criteria are scientifically
derived ambient concentrations  developed  by EPA or  states for various  pollutants of
concern to protect human health and aquatic life. Narrative criteria are statements that
describe the desired water quality goal.
Water quality standard

Description: Under Section 304 of the Clean Water Act (40 CFR Part 131), water quality
standards are regulations which consist of the beneficial designated use or uses of a water-
body, the numeric and narrative water quality criteria that are necessary to protect the use
or uses of that particular water-body, and an antidegradation statement.
                                         47

-------
             APPENDIX 1

           Tables 1, 2, and 3

Subsurface Contamination Reference Guide
           EPA/540/2-90/011
                 48

-------
 Subsurface
Remediation
 Guidance
Tables 1&2

-------
                    Table 1.  Contaminants Commonly Found  at Superfund  Sites
 Halogenated Volatile Organics

 Liquid Solvents

 Carbon Tetrachlonde
 Chlorobenzene
 Chloroform
 Cis-1,2-dichloroethylene (d)
 1,1-Dichloroethane (a)
 1,2-Dichloroethane
 1,1-Dichloroethylene
 1,2-Dichloropropane (a)
 Ethylene Dibromide (g)
 Methylene Chloride
 1,1,2,2-Tetrachloroethane
 Tetrachloroethylene
 Trans-1,2-dichloroethylene (d)
 1,1,1 -Trichloroethane
 1,1,2-Trichloroethane
Trichloroethylene

 Gases

Chloroethane
Vinyl Chloride
Non-Haloaenated Volatile
Qrganics

Ketones/Furans

Methyl Ethyl Ketone
4-Methyl-2-Pentanone
Tetrahydrofuran

Aromatics

Benzene(g)
Ethyl Benzene (g)
Styrene
Toluene (g)
m-Xylene (g)
o-Xylene (g)
p-Xylene (g)
  Inorganics

  Arsenic (As)
  Cadmium (Cd)
  Chromium (Cr)
  Cyanide (CN)
  Lead(Pb)
  Mercury (Hg)
  Selenium (Se)
  Iron (Fe) *
Halogenated Semivolatile
Organics

PCBs (b)

Aroclor 1242
Aroclor 1254
Aroclor 1260

Pesticides

Chlordane
ODD
DDE
DDT
Dieldrin

Chlorinated Benzenes

1,2-Dichlorobenzene
1,4-Dichlorobenzene

Chlorinated Phenols

Pentachlorophenol (w)
2,3,4,6-Tetrachlorophenol
Non-Halogenated Semivolatile
Organics

PAHs (e)

Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(ghi)perylene
Benzo(k)tluoranthene
Chrysene
Dibenz(a,h)anthracene
Fluoranthene
Fluorene
lndeno(1,2,3-cd)pyrene
2-Methyl naphthalene
Naphthalene
Phenanthrene
Pyrene

Non-Chlorinated Phenols

m-Cresol (e)
o-Cresol (e)
p-Cresol (e)
2,4-Dimethylphenol (e)
2,4-Dinitrophenol
Phenol
                 (a)     may be component of antiknock fluids added to fuel oils
                 (b)     constituent in some oils, greases, dielectric liquids, and thermostatic fluids
                 (d)     may be present in dye or lacquer solutions
                 (e)     constituent of crude oil fractions (including fuel and motor oils) and/or coal tar
                        fractions (including creosote); creosote may be present as DNAPL
                 (g)     constituent in fuel oils (e.g. gasoline)
                 (w)     combined with fuel oil #2 or kerosene when used as wood preservative

                 Note:   Some contaminants listed may be present in subsurface as biological or chemical degradation products of others

                 *       Although not normally classified as a contaminant, iron may strongly impact the subsurface behavior of other
                        contaminants and may govern which treatment processes can or cannot be used.

-------
Table 2.  Property Ratings of Chemical Classes Commonly Found at Superfund  Sites  (from Table 1)
                                       and Applicable Technologies for In-Situ Treatment
   Chemical
    Class
Melting
 Point
 Water
Solubility
 Vapor
Pressure
Henry'sLaw
 Constant
Density
Dynamic     Kinematic      Log        Log       Aerobic      Potential
Viscosity     Viscosity      Kov<        Koc    Biodegradability  Subsurface
                                                        Mobility
 Haloaenated Volatile Oraanics

   Liquid Solvents*          low       moderate/high

   Gases                  low           high

 Nonhaloaenated Volatile Oraanics

   Ketones/furans          low           high

   Aromatics               low       moderate/high


 Haloaenated Semivolatile Orqanics*

   PCBs                   low           low

   Pesticides               high         moderate


   Chlorinated Benzenes low/moderate     moderate

   Chlorinated Phenols  moderate/high     moderate
                           high

                           high



                           high

                           high
                        moderate/high

                            high



                          moderate

                            high
                            low         moderate

                            low       low/moderate


                          moderate        high

                            tow5          low1
Non-Haloaenated Semivolatile Oraanics

   PAHs               moderate/high   tow/moderate    moderate/low         f.

   Non-Chlorinated Pfteno/smoderate        high        moderde/low    low/moderate
                            high

                            low



                            low

                            low
                                         high

                                        low/high


                                         high

                                         high





                                         high

                                         high
                             t

                            NA
                          f       tow/moderate low/moderate      f

                         NA         low        low         ND
                            low       moderate       low        low         ND

                          moderate   moderate/high    moderate    moderate       high
                                        ND

                                        NA


                                        high

                                        NA
                                                                  NA

                                                                high/NA
                                        ND

                                        NA


                                       high

                                        NA
                                                   NA

                                                  high/NA
                                    high

                                    high
                                   high

                                   high
                                  moderate    moderate

                                    high       high"
                                                  high

                                                  low
                                              high

                                              low
  low

  low


  high

  highp




moderate

  high
moderate/high

   high



   high

  moderate




    low

    low


  moderate

    low




    low

   high
Inorganics

   Se, As, CN Cr (VI)
                                         For detailed information on subsurface transport and f;ilt; bvtuivior for these chemicals, see Table 3.
                                                                                                                        high*'
   Hg, Pb, Cd, Cr (III)
                                                                                                                         low*

-------
Table 2. Property Ratings of Chemical Classes Commonly Found at Superfund Sites (from Table 1)
and Applicable Technologies for In-Situ Treatment (continued)
ConsolidatedDeposits
UnconsolidatedDeposits" UnconsolidatedDeposits0 (SaturatedZone)
(VadoseZone) (SaturatedZone)
Chemical Fractured Karst
Class Homogeneous1 Heterogeneous2 Homogeneous' Heterogeneous' Bedrock Bedrock
Haloqenated Volatile Orqanics
Liquid Solvents'
Gases
Nonhalogenated Volatile Orqanjcs
Ketones/furans
Aroma tics
Haloqenated Semivolallle Organics*
PCBs
Pesticides
Chlorinated Benzenes
Chlorinated Phenols
Non-Haloaenated Semivolatile Oraanics
PAHs
Non-Chlorinated Phenols
Inoraanics
Se, As, CN, Cr (VI)
Hg, Pb, Cd, Cr (III)

SVE(1)
SF(5)
SVE(1)

SVEB(5)
SF(5)
SVE(1)
SF(5)

SF3(5)
ISV(5)
SF3(5)
ISV(5)
SVEB(5)
SF(5)
SF(5)
SVEB(5)
SVEB(5)
SF3(5)
SF(5)
SVEB(5)
SF(5)
ISV(5)
ISV(5)
SF3(10)

SVE(5)
SF(5)
SVE(5)

SVEB(5)
SF(5)
SVE(5)
SF(5)

ISV(5)
SP(5)
ISV(5)
SP(5)
SVF_B(5)
SF{5)
SF(5)
SVEB(10)
SVEB(10)
SP(10)
SF(10)
SVEB(10)
ISV(5)
SF(5)
ISV(5)
SP(10)

P&T + ISB(1)
P&T(1)
P&T(1)

P&T(1)
P&T + ISB(1)
P&T(5)

P&T + CE'(5)
P&T(10)
P&T + CE'(5)
P&T(10)
P&T + ISB(1)
P&T(5)
P&T + ISB(1)
P&T(5)
P&T+CE'(5)
P&T + ISB(5)
P&T + ISB(1)
P&T(1)
P&T(1)
P&T(5)
P&T + CE<(5)

P&T + ISB(5)
P&T(5)
P&T(5)

P&T(5)
P&T + ISB(5)
P&T(5)

P&T + CE<(10)
P&T(10)
P&T+CE'(10)
P&T(10)
P&T + ISB(5)
P&T(5)
P&T + ISB(5)
P&T(10)
P&T + CE'(10)
P&T + ISB(10)
P&T + ISB(5)
P&T(5)
P&T(5)
P&T(10)
P&T+CE'(10)

P&T(10)
P&T(10)

P&T(10)
P&T(10)

P&T(10)
P&T(10)
P&T(10)
P&T(10)
P&T(10)
P&T(10)
P&T(10)
P&T(10)

P&T(5)
P&T(5)

P&T(5)
P&T(5)

P&T(10)
P&T(10)
P&T(5)
P&T(10)
P&T(10)
P&T(5)
P&T(5)
P&T(10)

-------
Rating


Melting
Point
fC)
Water
Solubility
(mg/l)
Vapor
Pressure
(mmHg)
Henry'sLaw
Constant
(atm-nf/mol)
Density

(g/cc)
Dynamic
Viscosity
(centipoise)
Kinematic
Viscosity
(centistokes)
Log
K
ow

Log
KOC

Aerobic
Biodegradability

Potential
Subsurface
Mobility*
Table 2.  Property Ratings of Chemical  Classes Commonly Found at Superfund  Sites (from Table 1)
                              and Applicable Technologies for In-Situ Treatment (continued)
                                                                 QualitativeRatingKey'
Low
Moderate
High
<13.00
>13.00
<100.00

>100.00
<1.00E+00
>1.00E+00
<1.00E+03

>1.00E+03
                                             <1.00E-03
>1.00E-03
<1.00E+00

>1.00E+00
                                    <1.00E-05
>1.00E-05
<1.00E-03

>1.00E-03
                                                                         =1
>r
                                       <0.6
           ;0.6
                                                                         <0.4
>0.4
<0.8

>0.8
<2.5




<3.5

>3.5
                                                         <2.2
>2.2
<3.2

>3.2
                                                   veryslowor    logKoc>3.2
                                                   negligible
moderate   2.2
-------
Table 2.  Property Ratings of Chemical Classes Commonly Found at Superfund Sites (from Table 1)
                             and Applicable Technologies for  In-Situ Treatment (continued)
                                          Treatment Technologies

                                        P&T  -  Pump & Treat
                                        ISB   -  Bioremediation8
                                        CE   -  Chemical Extraction
                                        ISV   -  In-Situ Vitrification
                                        SF   -  Soil Flushing
                                        SVE  -  Soil Vacuum Extraction
   Uncertainty Rating Key

        (1) Low
        (5) Moderate
       (10) High

Refers to  uncertainty in restoring soil/
ground water to health-based  or MCL
levels, assuming no NAPLs are  present.
                            Biodegradative processes occur naturally in the subsurface. In situ bioremediation involves the enhancement of these
                            processes through the addition of amendments such as oxygen and/or nutrients

                            Unconsolidated deposits refer to gravel, sand, silt or clay or any combination thereof.  Deposits consisting primarily
                            of clay are difficult to remediate and excavation or containment may be the only applicable remedial options

                            Indicates that the application of soil vacuum extraction will partly or primarily be for purposes of stimulating
                            biodegradative processes

                            Refers to a subsurface regime in which the variability in hydraulic conductivity is less than one order of magnitude

                            Refers to a subsurface regime in which the hydraulic conductivity within the treatment zone varies by more than one
                            order of magnitude. A heterogeneous subsurface regime may be layered (stratified) or trending.  In general, a
                            trending subsurface regime  will be more amenable to treatment than a layered subsurface regime

                            Water alone will not suffice as a soil flushing extractant

                            Refers to the use of surfactants or other chemicals to enhance the mobility of contaminants. This technology should
                            be considered with caution because of its limited success to date and because of the potential environmental impact
                            of introduced chemicals

-------
 Subsurface
Remediation
 Guidance
  Table 3

-------
Table 3. Properties
Chemical Melting Waterf
Point Solubility
(°C) (mg/l)
of Contaminants Commonly Found at Superfund Sites
Vaporf Henry'sLawf Density! Dynamicf Kinematic! Log Log
Pressure Constant Viscosity Viscosity «o w KOC
(mmHg) (atm-m1' mo I ) (9/cc) (CP) (cs)
Aerobic
Biodegrad-
abilily
MCL(17]
(mg/l)
Halogenated Volatile Organics
Liquid Solvents
Carbon Tetrachlonde
Chlorobenzene
Chlorolorm
Cis-1 ,2-dichloroethylene(d)
I.l-Dichloroethane(a)
1,2-Dichloroethane
1,1-Dichloroethylene
1,2-Dichloropropane(a)
EthyleneDibromide(g)
MethyleneChloride
1 .1 ,2,2-Telrachloroethane
Tetrachloroethylene
Trans-1,2-dichloroethylene(d)
1,1,1-Tnchloroethane
1,1,2-Tnchloroethane
Trichloroethylene
Gases
Chloroethane(b.p.12.5C)
VinylChloride(b.p.-13.9C)

- 23 [7]
• 45 R)
- 64 [7]
- 81 [71
- 97 4 p]
- 35.4 [7]
-122.5 [7]
- 90 [7]
997[7]
- 97 [7]
- 43 [7]
- 22.7 [7]
- 50 [7]
- 32 [7]
- 36 [7]
- 87 [7]

-138.3 [7]
-157 [7]

8 E+02 [1]
4.9 E+02 [1]
8.22 E+03 [1]
3.5 E+03 [1]
5.5 E+03 [1]
8.69 E+03 [1]
4 E+02 [1]
2.7 E+03 [1]
3.4 E+03 [1]
1.32 E+04 [1]
2.9 E+03 [1]
1.5 E+02 [1]
6.3 E+03 [1]
95 E+02 [1]
4.5 E+03 [7]
1 E+03 [1]

5.7 E+03 [1]
1.1 E+03 [1]

913 E+01 [1]
88 ErOO [1]
1.6 E+02 [1]
2 E+02'[7]
1 82 E+02 [1]
6.37 E+01 [1]
5 E+02 [1]
395 E+01 [1]
1.1 E+01 (1)
3.5 E+02 [1]
4.9 E+00 [1]
1.4 E+01 [1]
2.65 E+02 [3]
1 E+02 [1]
1 88 E+01 [3]
5.87 E+01 [1]

1 E+03 [1]
2.3 E+03 [1]

2 E-02 [ 1 ]
346 E-03 '[1]
3,75 E-03 '[1]
7,5 E-03 '[1]
57 E-03 '[1]
1 1 E-03 '(I]
1.54 E-01 '[1]
36 E-03 '[1]
3 18 E-04 [1]
257 E-03 '[1]
5 E-04 '[1]
2.27 E-02 '[1]
66 E-03 '(I]
276 E-03 '[1]
1.17 E-03 J[11]
8.92 E-03 '[1]

11 E-02 [1]
6.95 E-01 [1]

1.5947 [1]
1 106 [1]
1 485 [1]
1 284 [1]
1.175 [1]
1 253 [1]
1.214 [1]
1.158 [1]
2172 [1]
1 325 [1)
1.600 [1]
1 625 [1]
1.257 [1]
1 325 [1]
1.4436 [5]
1.462 [1]

0.9414 OC[1]
0.9121 15C[3]

0965 [1]
0.756|1]
0.563 [1]
0467 [1]
0377 [1]
084 [1]
0 33 [1[
0.84 [1]
1 67621C[1]
0.43 [1]
1.77 [1]
0.89 [1]
0.404 [1]
0.858 [1]
0.119 [3]
0.570 [1]

na
na

0.605 (c)
0683 (c)
0 379 (c)
0 364 (c)
0 321 (c)
0.67 (c)
0.27 (c)
0.72 (c)
0.79 [3]
0.324 (c)
1.10 (c)
0.54 (c)
0.321 (c)
0.647(c)
0824(c)
0.390 (c)

na
na

2.83(1]
2.84(1]
1.97(1]
1 86(1]
179[1]
1.48(1]
2.13 [1]
2.02 [1]
1.76[1]
1.25(1]
2.39(1]
3.14(1]
2.09(1]
2.49(1]
2.17(4]
2.42(1]

1.43(1]
0.60(4]

2.64(1]
22 [1]
1 64(1]
1.5 [1]
1.48(1]
1.15(1]
181(1]
1.71(1]
1.45(1]
0.94 [1]
234(1]
2.82(1]
1.77(1]
2.18(1]
1 75(13]
2.10(1]

1.17(1]
0.91 [1]

D[2]
D5.A10|2]
A [2]
B[2]
A [2]
B [2]
A [2]
A [2]
nd
D [2]
N [2]
A [2]
B [2]
C [2]
C [2]
A [2]

nd
nd

5 (1)
100 (p)
nd
70 (p)
nd
5 (1)
7 (D
5 (P)
0.05(p)
5 (1)
nd
5 (P)
70(p)
200 (1)
nd
5 (f)

nd
2 (f)
Non-Halogenated Volatile Organics
Ketones/furans
Methyl ElhylKetone
4-Melhyl-2-Pentanone
Tetrahydroluran

- 86.4 [7]
- 83 [7)
-108.5 [7]

2.68 E+05 [11]
1 9 E+04 [3]
3 E+05'[6)

7.12 E+01 [3]
1.6 E+01 [3]
4.56 E+01 t(4]

2.74 E-05 t[11]
1.55 E-04 }[13]
1.1 E-04 J(14]

0.805 (5]
0.8017 [7]
0.8892 [6]

0.40 [3]
0.5848[3]
0.55 [13]

0.497(c)
0.729(c)
0.618 (c)

0.29 [17]
1.25
046 [14]

0.65 [11]
1.38(15]
nd

nd
nd
nd

nd
nd
nd

-------
Chemical
Table 3. Properties of Contaminants Commonly Found
at Superfund Sites (continued)
Melting Water t Vapor f Henry's Law f Density t Dynamict Kinematicf Log
Point Solubility Pressure Constant Viscosity Viscosity Kow
(°C) (mg/l) (mmHg) (atm-nf/mol ) (g/cc) (cp) (cs)
Aromatics
Benzene(g) 5.5 [7]
EthylBenzene(g) -94. 97 [7]
Styrene -30.6 [7]
Toluene(g) -95.1 [7]
m-Xylene(g) -50 [7]
o-Xylene(g) -25 [7]
p-Xylene(g) 13 [7]
Halogenated Semivplatile Ornanic
PCBs (b)
Aroclor1242
Aroclor1254
Aroclor1260
Pesticides
Chlordane
ODD
DDE
DDT
Dieldrin
Chlorinated Benzenes
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Chlorinated Phenols
Pentachlorophenol(w)
2,3,4,6-Tetrachlorophenol

-19 [1]
10 [1]
nd

106 [1]
112 [7]
88.4 [1]
108 [7]
176.5 [7]

-17 [7]
53 [7]

190 [7]
69.5 [7]
1.78E+03 [1]
1.52E+02 [1]
3 E+02 [7]
5.15 E+02 [1]
2 E+02 [3]
1.7 E+02 [3]
1.98 E+02'[3]
S
4.5 E-01'[1]
1.2 E-02 [1]
2.7 E-03 [1]

5.6 E-02*[1]
1.60 E-0124C[7]
4.0 E-02 [7]
3.1 E-03 [1]
1.86 E-01 J[4]

1 E+02 [1]
8 E+01 [1]

1.4 E+01 [1]
1.00 E+03t[11]
7.6 E+01 [1] 5.43 E-03 '[13] 0.8765 [1]
7 E+00 [1] 7.9 E-03 '[1] 0.867 [7]
5 E+00 [7] 2.28 E-03 [7) 0.9060 [13]
2.2 E+01 [1] 6.61 E-03 '[13] 0.8669 [1]
9 E+00 [1] 6.91 E-03 '[1] 0.8642 '[1]
7 E+00 [1] 4.94 E-03 '[1] 0.880 *[1]
9 E+00 [1] 7.01 E-03 '[1] 0.8610 *[1]
4.06 E-04'[9] 3.4 E-04 [1] 1.385 [1]
7.71 E-05'[9] 2.8 E-04 [1] 1.538 +-[9]
4.05 E-05'[9] 3.4 E-04 [1] 1.4430C[1]

1 E-05 [1] 2.2 E-04 '[1] 1.6 *[1]
1 E-06 30C[17] 7.96 E-06 t[11] 1.385 [17]
6.40 E-06 [1] 1.9 E-04 '[1] nd
1.5 E-07 [1] 2.8 E-05 '[1] 0.985 [1]
1.78 E-07 [3] 9.7 E-06 *[8] 1.75 [3]

9.6 E-01 [1] 1.88 E-03 *[1] 1.306 [1]
6 E-01 [1] 1.58 E-03 *[1] 1.2475 [1]

1.1 E-04 [1] 2.8 E-06 [1] 1.978 [1]
nd nd 1.839 *[5]
0.6468(1] 0.7379(c) 2.13 [1]
0.678 [3] 0.782 (c) 3.15 [1]
0.75! [13] 0.829 (c) 3.16 [14]
0.58 [1] 0.669 (c) 2.73 [1]
0.608(1] 0.717(3] 3.20(1]
0.802(1] 0.932(3] 3.12(1]
0.635(1] 0.753(3] 3.15(1]
nd nd 5.58 [9]
nd nd 6.03 [9]
nd nd 7.15(9]

1.104 [3] 0.69 (c) 5.48(1]
na na 5.56(1]
na na 5.69(1]
na na 6.36(1]
na na 5.34 [4]

1.302 [1] 0.997 (c) 3.38 [1]
1.258 [1] 1.008 (c) 3.39(1]

na na 5.12(1]
na na 4.1 [11]
Log
Koc
1.81 [1]
2.83(1]
nd
2.41 [1]
2.84(1]
2.84(1]
2.84(1]
5 [1]
nd
nd

4.58(1]
5.38(1]
5.41 [1]
5.48(1]
3.23 [14]

3.06[1]
3.07(1]

4.80(1]
2.0 [11]
Aerobic MCL[17]
Biodegrad-
ability (mg/l)
D[2]
D5,A10[2]
nd
D[2]
nd
nd
nd
N [2]
N [2]
N [2]

N [2]
M[2]
M [2]
M[2]
N [2]

T [2]
T [2]

A [2]
nd
5 (f)
700 (p)
nd
2000 (p)
10000(p)
10000(p)
10000(p)
nd
nd
nd

2 (P)
nd
nd
nd
nd

600 (p)
750 (f)

nd
nd

-------
Table 3. Properties of Contaminants Commonly Found
at Superfund Sites (continued)
Chemical Melting Walerf Vaporf Henry'sLawf Densityt Dynamicf Kinematicf Log Log Aerobic MCL[17]
Point Solubility Pressure Constant Viscosity Viscosity KO w Koc Biodegrad-
(°C ) (mg/l) (mmHg) (atm-m5/ mo I ) (g/cc) (cp) (cs) ability (mg/l)
Non-Haloaenated Semivolatile Orqanics
PAHs (e)
Acenaphthene
Anthracene
Benzo(a)anlhracene
Benzo(a)pyrene
Benzo(b)tluoranlhene
Benzo(ghi)perylene
Benzo(k)lluoranlhene
Chrysene
Dibenz(a,h)anthracene
Fluoranthene
Fluorene
lndeno(1 ,2.3-cd)pyrene
2-Methylnaphlhalene
Naphthalene
Phenanlhrene
Pyrene
Non-Chlorinated Phenols
Dheio
2 4-Dimeihvlphencve
2.4-Dmrtrophenol
m-Cresol(e)
o-Cresol(e)
p-Cresol(e)

92.5 [7]
216.3 [7]
167 [4]
179 [7]
167 [4]
278 [12]
217 [12]
254 [7]
266.5 [7]
107 [7]
116.7 [12]
163 [12]
34 58 [7]
80.2 [4]
100 [7]
150 [7]

41 [7]
26 [7]
112 [7]
12 [7]
31 [7]
34.8 [7]

3.88 E+00 '[8]
7.5 E-02 '[8]
1.4 E-02 '[12]
3.8 E-03 t[12]
1.4 E-02 t[11]
2.6 E-04 '[7]
4.30 E-03 }[11]
6 E-03 '[7]
2.5 E-03 i(12]
2.65 E-01 '[7]
1.90 E+00 '[8]
5.30 E-04 i[11]
2.54 E+01 '[8]
3.1 E+01 '[12]
1.18 E+00 '[8]
1.48 E-01 '[8]

8.4 E+04 [1]
6.2 E+03 *[3]
6 E+03 '[3]
2.35 E+04 [7]
3.1 E+04 40C[7]
2.40 Ej-04 40C[7]

2.31 E-02 '(8]
1.08 E-05 '[8]
1.16 E-09 i(11]
549 E-09 §(18]
5.00 E-07 t[12]
1 E-10 [14]
9.59 E-11 [14]
6.3 E-09 '[14]
1 E-10 t(12]
E-02[10]E-06[12]
6.67 E-04 '(8)
1 E-10+-[11]
6.80 E-02 '[8]
2.336E-01 '[12]
2.01 E-04 '[8]
6.67 E-06 '[8]

5.293E-01 [1]
9.8 E-02 *[3]
1.49 E-05 flU)
1.53 E-01 '[12]
2.45 E-01 '[12]
1.08 E-01 '[12]

1.20 E-03 *[c]
3.38 E-05 'JCJ
4.5 E-06 [12]
1 8 E-05 t(12]
1.19 E-05 t[11]
5.34 E-08 i[11]
3.94 E-05 t(11]
1.05 E-06 '[14]
7.33 E-08 t(11]
6.5 E-06 '(14]
7.65 E-05 '[c]
6.95 E-08 '[14]
5.06 E-02 '[c]
1.27 E-03 '[c]
3.98 E-05 '[c]
1.20 E-05 '[c]

7.80 E-07 [c]
2.5 E-06 '[c]
6.45 E-10 [11]
3.8 E-05 +-[12]
4.7 E-05 +-[12]
3.5 E-04 +-[12]

1.225(12]
1.25 [12]
1.174(12]
nd
nd
nd
nd
1.274 (7]
1.252 [12]
1.252 [12]
1.203 [12]
nd
1.0058 [12]
1.162 [12]
0.9800 [12]
1.271 [12]

1.0576 41C[1]
1.036 [7]
1.68 [3]
1.038 [7]
1.0273 [12]
1.0347 [7]

na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na

3.0250C[1]
na
na
21 [12]
na
na

na
na
na
na
na
na
na
na
na
na
na
na
na
na
na
na

3.87 46C
na
na
20 (c)
na
na

3. 92 [12]
4.45 (12]
5.61 [12]
6.06(11)
6.57 [12]
6.51 [11]
6.06(11]
5.61 (11]
6.80 [11]
4.90(12]
4.18(12]
6.5 [11]
3.86(12]
3.30(12]
4.46 [12]
4.88 [12]

1.46 (1)
2.50 [4]
1.54 [3]
1.96 [12]
1.95 [12]
1.94 [7]

3. 7 [11]
4.1 [11]
6.14(11]
6.74(11]
5.74[11]
6.2 [11]
5.74(11]
5.3 (11)
6.52(11]
4.58(11]
3.9 [11]
6.2 [11]
3.93(14]
3.11 [14]
4.1 [11]
4.58[11]

1.15(11]
2.35(14]
1.22(11]
1.43(15]
1.23(15)
1.28(15]

D[2]
A|2]
N(2]
nd
nd
nd
nd
A5,N10[2]
nd
A5,N10[2]
A [2]
nd
nd
D [2]
D [2]
D5,N10[2)

D [2]
D [2]
D [2]
nd
nd
nd

nd
nd
nd
02 (I)
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd
nd

nd
nd
nd
nd
nd
nd

-------
           Table 3.   Properties of Contaminants  Commonly Found
                                  at Superfund  Sites (continued)
CHEMICAL
                                                                                                                 MCL
Inorganics

arsenic(As)




cadmium (Cd)



chromium (Cr)



cyanide (CN)



iron(Fe)
lead(Pb)
mercury(Hg)
selenium(Se)
May occur in morethanoneoxidation state in subsurface. Arsenateform(As043~) will dominate underoxidizing
conditions. Moretoxicandmobilearseniteform(As03') maydominateunderincreasingly reducing and acidic
conditions.Volatilealkylated-Ascompoundsmayformunderredudngconditions.VolatilearsinefAsHJ may
formunder highly reducing conditions. Adsorptionofarsenateandarsenite forms will generally increase withdecreasingpH.

Occursonlyindivalentforminaqueoussolutions(e.g.Cd!*,CdCI*,CdS04°).Cd2»tendstobedominantspecies.
Adsorption behaviorcorrelates with cationexchange capacity (CEC)ofsoilandaquifermaterial. Adsorption/
precipitation increases with increasingpH with most Cdprecipitatingout at pH>6.

May occur in morethanone oxidation statein subsurface. Trivalent form (Cr III) isdominant under pH and redox
conditions generally present insubsurlace.Cr III maybeconvertedto highly mobile andtoxichexavalent form
(Cr VI) underoxidizing conditions. Cr III is readily adsorbed inthesubsurfacewhileCr VI is not.

Cyanide ion (CN~ (predominatesin aqueous solution only at pH>9. Hydrogen cyanide (HCN) predominates at pH<9. H CN i s
volatile(v.p.741mmHgat25C)andtoxic.CN'behavessimilartohalideionsandtendstocomplexwithiron.Undissolvedcyanide
salts may bepresent in vadosezone.

May occur in morethan one oxidationstateinthe subsurface. Ferrous form (Fe2*) is most soluble and mobile, and
dominates underreducingconditions. Underoxidizing conditions, ferrousform isconvertedtoferricform(Fe3*).
Ferricform is less soluble, less mobile, and willtendtoprecipitate.Compoundsandmetalscomplexedtoiron may
be removed from solution throughtheprecipitationprocess.Conversely, compoundsand metals adsorbed to iron
inthesubsurface maybe increasingly mobilized under increasinglyreduced conditions. Precipitated iron may
hindertreatment processes such asin-situbioremediation and airstripping.

DominantspeciesinaqueoussolutionarePb2* underacidicconditionsandPb2*-carbonate complexes under
alkaline conditions. Adsorptionbehaviorcorrelateswithcationexchangecapacity(CEC)of soil and aquifer
material. Adsorption/precipitation JncreaseswithincreasingpHwithmostPbprecipitatingoutatpH>6. Volatile
alkylated-Pbcompoundsmaybepresentormaylorm under reducirigconditions.

Mayoccur in morethanoneoxidation state. May occur in subsurface in mercuricform(Hg2*),mercurous form
(Hg22*), elemental form (Hg°), and in alkylated form (e.g. methyl and ethyl mercury). Hg22*andHg2-are more
stable under oxidizing conditions and arestrongly adsorbed by soils. Hg°andalkylated forms are morestable under
reducing conditions. Conversion to alkylated forms may occur underreducing conditions. Hg°and a Iky la ted-
Hgforms are volatile, toxic, and may not be as strongly adsorbedbysoils.

May occurin morethan one oxidation statein subsurface. Selenateform(Se042  ) will dominate underoxidizing
conditions. Seleniteform(Se032)willdominateunderincreasingly reducing conditions. SelenideformfSe2 •) may
dominate under highly reducing conditions. Selenate and selenite are more soluble and mobile forms. Adsorption
ofselenateandselenitewillgenerallyincrease withdecreasingpH. Volatilealkylated-Secompoundsmayform
under reducing conditions.
    nd
   5(P)
100(p)
 200 (t)
 300 (f)
                                                                                                                                5(P)
 2(P)
50 (p)

-------
Table  3.  Properties of Contaminants  Commonly Found
                      at  Superfund Sites  (continued)
 A    -    significant degradationwithgradualadaption
 B    -    slowtomoderateactivity.concomilantwithsigmlicant raleotvolatilizalion
 C    -    veryslowbiodegradativeactivity.withlongadaptionperiodneeded
 D    -    significant degradation with rapid adaption
 M    -    notsignificantlydegradedundertheconditionsofthe testmethod
 N    -    not significantly degiadedunderthe conditions of test method and/or precluded by extensive rate ol voiatilization
 T    -    significantdegradationwithgradualadaptionfollowedbydeadaptiveprocessinsubsequentsubcultures(toxicity)


 (a)   -    maybecomponentolantiknockfluidsadded to fueloils;remedialtreatment may require consideration of
          constituent in oil phase
 (b)   -    constituentinsomeoils,greases, dielectricliquids, and thermostatic fluids; remedial treatment may require
          consideration of constituent in oil phase
 (c)   -    calculated
 (d)   -    maybepresentindyeor lacquer solutions; remedialtreatment may requireconsideration of constituent in oil phase
 (e)   -    constituentof crude oil fractions (including fuel oils and motor oils) and/or coal tar tract ions (including creosote);
          creosote maybe present as DNAPL; remedial treatment may requireconsideration of constituent in oilphase
 (f)    -    final MCL
 (g)   -    constituent in fuel oils (e.g. gasoline); remedial treatment may requireconsiderationof constituent in oil phase
 (p)   -    proposed MCL
 (I)    -    tentativeMCL
 (w)   -    combined with lueloil #2 orkerosenewhenusedas wood preservative; remedialtreatmentmay require
          consideration of constituentinoilphase

 na   -    not applicable
 nd    -    nodatafound

 Reference

 f    -    Valuesaregivenat20°Cunlessotherwisespecified

          Valueisat25°C

 J    -    Valueisatunknowntemperaturebutisassumedtobeat20-30°C

-------
                APPENDIX 2
Table for Hydraulic Conductivity Units Conversion
Unit
1 meter/day
1 centimeter/second
1 foot/day
1 gallon/day/ ft2
m/d
1
8.64 x 102
3.05 x 10'1
4.1 x lO'2
cm/s
1.16 x lO'3
1
3.53 x 1Q-4
4.73 x 1(T5
ft/day
3.28
2.83 x 103
1
1.34 x 10'1
gal/day/ft2
2.45 x 101
2.12 x 104
7.48
1

-------
                               APPENDIX 3
                          U.S.D.A. Soil Texture Triangle
                                 100
   % by Weight Clay
                                  Clay loam
                                 Y//////
% by Weight Silt
                                                           100
O
O
             100 90   80  70   60   50  40   30  20   10
              ^	
                            % by Weight Sand

-------