ASTM D6030-96(2008)
(Guide)Standard Guide for Selection of Methods for Assessing Groundwater or Aquifer Sensitivity and Vulnerability
Standard Guide for Selection of Methods for Assessing Groundwater or Aquifer Sensitivity and Vulnerability
SIGNIFICANCE AND USE
Sensitivity and vulnerability methods can be applied to a variety of hydrogeologic settings, whether or not they contain specifically identified aquifers. However, some methods are best suited to assess groundwater within aquifers, while others assess groundwater above aquifers or groundwater in areas where aquifers have not been identified.
Intergranular media systems, including alluvium and terrace deposits, valley fill aquifers, glacial outwash, sandstones, and unconsolidated coastal plain sediments are characterized by intergranular flow, and thus generally exhibit slower and more predictable groundwater velocities and directions than in fractured media. Such settings are amenable to assessment by the methods described in this guide. Hydrologic settings dominated by fracture flow or flow in solution openings are generally not amenable to such assessments, and application of these techniques to such settings may provide misleading or totally erroneous results.
The methods discussed in this guide provide users with information for making land- and water-use management decisions based on the relative sensitivity or vulnerability of underlying groundwater or aquifers to contamination. Most sensitivity and vulnerability assessment methods are designed to evaluate broad regional areas for purposes of assisting federal, state, and local officials to identify and prioritize areas where more detailed assessments are warranted, to design and locate monitoring systems, and to help develop optimum groundwater management, use and protection policies. However, some of these methods are independent of the size of the area evaluated and, therefore, can be used to evaluate the aquifer sensitivity and vulnerability of any specific area.
Many methods for assessing groundwater sensitivity and vulnerability require information on soils, and for some types of potential groundwater contaminants, soil is the most important factor affecting contaminant movement and attenuation fro...
SCOPE
1.1 This guide covers information needed to select one or more methods for assessing the sensitivity of groundwater or aquifers and the vulnerability of groundwater or aquifers to water-quality degradation by specific contaminants.
1.2 This guide may not be all-inclusive; it offers a series of options and does not specify a course of action. It should not be used as the sole criterion or basis of comparison, and does not replace professional judgment.
1.3 This guide is to be used for evaluating sensitivity and vulnerability methods for purposes of land-use management, water-use management, groundwater protection, government regulation, and education. This guide incorporates descriptions of general classes of methods and selected examples within these classes but does not advocate any particular method.
1.4 Limitations—The utility and reliability of the methods described in this guide depend on the availability, nature, and quality of the data used for the assessment; the skill, knowledge, and judgment of the individuals selecting the method; the size of the site or region under investigation; and the intended scale of resulting map products. Because these methods are being continually developed and modified, the results should be used with caution. These techniques, whether or not they provide a specific numeric value, provide a relative ranking and assessment of sensitivity or vulnerability. However, a relatively low sensitivity or vulnerability for an area does not preclude the possibility of contamination, nor does a high sensitivity or vulnerability necessarily mean that groundwater or an aquifer is contaminated.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establis...
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Designation: D6030 − 96(Reapproved 2008)
Standard Guide for
Selection of Methods for Assessing Groundwater or Aquifer
Sensitivity and Vulnerability
This standard is issued under the fixed designation D6030; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This guide covers information needed to select one or
bility of regulatory limitations prior to use.
more methods for assessing the sensitivity of groundwater or
1.7 This guide offers an organized collection of information
aquifers and the vulnerability of groundwater or aquifers to
or a series of options and does not recommend a specific
water-quality degradation by specific contaminants.
course of action. This document cannot replace education or
1.2 This guide may not be all-inclusive; it offers a series of
experience and should be used in conjunction with professional
optionsanddoesnotspecifyacourseofaction.Itshouldnotbe
judgment. Not all aspects of this guide may be applicable in all
used as the sole criterion or basis of comparison, and does not
circumstances. This ASTM standard is not intended to repre-
replace professional judgment.
sent or replace the standard of care by which the adequacy of
1.3 This guide is to be used for evaluating sensitivity and a given professional service must be judged, nor should this
document be applied without consideration of a project’s many
vulnerability methods for purposes of land-use management,
water-use management, groundwater protection, government unique aspects. The word “Standard” in the title of this
document means only that the document has been approved
regulation, and education.This guide incorporates descriptions
of general classes of methods and selected examples within through the ASTM consensus process.
these classes but does not advocate any particular method.
2. Referenced Documents
1.4 Limitations—The utility and reliability of the methods
2.1 ASTM Standards:
described in this guide depend on the availability, nature, and
D653 Terminology Relating to Soil, Rock, and Contained
quality of the data used for the assessment; the skill,
Fluids
knowledge, and judgment of the individuals selecting the
D5447 Guide for Application of a Ground-Water Flow
method; the size of the site or region under investigation; and
Model to a Site-Specific Problem
the intended scale of resulting map products. Because these
D5490 Guide for Comparing Ground-Water Flow Model
methods are being continually developed and modified, the
Simulations to Site-Specific Information
results should be used with caution.These techniques, whether
D5549 Guide for The Contents of Geostatistical Site Inves-
or not they provide a specific numeric value, provide a relative
tigation Report (Withdrawn 2002)
ranking and assessment of sensitivity or vulnerability.
D5717 Guide for Design of Ground-Water Monitoring Sys-
However, a relatively low sensitivity or vulnerability for an
tems in Karst and Fractured-Rock Aquifers (Withdrawn
area does not preclude the possibility of contamination, nor
2005)
does a high sensitivity or vulnerability necessarily mean that
D5880 Guide for Subsurface Flow and Transport Modeling
groundwater or an aquifer is contaminated.
1.5 The values stated in SI units are to be regarded as
3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions—Many of the terms discussed in this guide
standard.
are contained inTerminology D653.The reader should refer to
1.6 This standard does not purport to address all of the
this guide for definitions of selected terms.
safety concerns, if any, associated with its use. It is the
3.2 Definitions:
1 2
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and is the direct responsibility of Subcommittee D18.21 on Groundwater and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Vadose Zone Investigations. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Sept. 15, 2008. Published November 2008. Originally the ASTM website.
approved in 1996. Last previous edition approved in 2002 as D6030–96(2002). The last approved version of this historical standard is referenced on
DOI: 10.1520/D6030-96R08. www.astm.org.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
D6030 − 96 (2008)
3.2.1 groundwater region, n—an extensive area where rela- 4.3 Many methods for assessing groundwater sensitivity
tively uniform geology and hydrology controls groundwater and vulnerability require information on soils, and for some
movement. types of potential groundwater contaminants, soil is the most
important factor affecting contaminant movement and attenu-
3.2.2 hydrogeologic setting, n—a composite description of
ationfromthelandsurfacetogroundwater.Therelativelylarge
allthemajorgeologicandhydrologicfeatureswhichaffectand
surface area of the clay-size particles in most soils and the
control groundwater movement into, through, and out of an
soils’contentoforganicmatterprovidesitesfortheretardation
area (1).
and degradation of contaminants. Unfortunately, there are
3.2.3 sensitivity, n— in groundwater, the potential for
significant differences in the definition of soil between the
groundwater or an aquifer to become contaminated based on
sciences of hydrogeology, engineering, and agronomy. For the
intrinsic hydrogeologic characteristics. Sensitivity is not de-
purposes of this guide, soils are considered to be those
pendent on land-use practices or contaminant characteristics.
unconsolidated organic materials and solid mineral particles
Sensitivity is equivalent to the term “intrinsic groundwater
that have been derived from weathering and are characterized
vulnerability” (2).
by significant biological activity. In the United States, these
3.2.3.1 Discussion—Hydrogeologic characteristics include
typicallyincludeunconsolidatedmaterialsthatoccurtoadepth
the natural properties of the soil zone, unsaturated zone, and
of2to3mor more.
saturated zone.
4.3.1 In many areas, significant thicknesses of unconsoli-
3.2.4 vulnerability, n—in groundwater, the relative ease
dated materials may occur below the soil. Retardation, degra-
with which a contaminant can migrate to groundwater or an
dation, and other chemical attenuation processes are typically
aquifer of interest under a given set of land-use practices,
less than in the upper soil horizons.These underlying materials
contaminant characteristics, and sensitivity conditions. Vulner-
maybetheresultofdepositionalprocessesormayhaveformed
ability is equivalent to “specific groundwater vulnerability.”
in place by long-term weathering processes with only limited
biological activity. Therefore, when compiling the data re-
4. Significance and Use
quired for assessing groundwater sensitivity and vulnerability,
it is important to distinguish between the soil zone and the
4.1 Sensitivity and vulnerability methods can be applied to
underlying sediments and to recognize that the two zones have
avarietyofhydrogeologicsettings,whetherornottheycontain
significantly different hydraulic and attenuation properties.
specifically identified aquifers. However, some methods are
best suited to assess groundwater within aquifers, while others
5. Description of Methods
assess groundwater above aquifers or groundwater in areas
where aquifers have not been identified.
5.1 Hydrogeologic Settings and Scoring Methods—This
4.1.1 Intergranular media systems, including alluvium and
group of methods includes those that involve geologic map-
terrace deposits, valley fill aquifers, glacial outwash, sand-
ping, evaluation, and scoring of hydrogeologic characteristics
stones, and unconsolidated coastal plain sediments are charac-
to produce a composite sensitivity map or composite vulner-
terized by intergranular flow, and thus generally exhibit slower
ability map, or both. The methods range from purely descrip-
and more predictable groundwater velocities and directions
tive of hydrogeologic settings to methods incorporating nu-
than in fractured media. Such settings are amenable to assess-
merical scoring. They can include descriptive information or
ment by the methods described in this guide. Hydrologic
quantitative information, or both, and the maps can be applied
settings dominated by fracture flow or flow in solution open-
as a “filter” to exclude specific hydrogeologic units from
ings are generally not amenable to such assessments, and
further consideration or select sensitive areas for further study.
application of these techniques to such settings may provide
5.1.1 The concept of assessing groundwater sensitivity and
misleading or totally erroneous results.
vulnerability is relatively recent and still developing. Thus, the
4.2 The methods discussed in this guide provide users with methodspresenteddifferbecausetheyhavebeendevelopedfor
information for making land- and water-use management
different purposes by different researchers using various types
decisions based on the relative sensitivity or vulnerability of
of data bases in several hydrogeologic settings. These methods
underlying groundwater or aquifers to contamination. Most
have been divided into three groups: assessments using hydro-
sensitivity and vulnerability assessment methods are designed
geologic settings without scoring or rankings, assessments in
to evaluate broad regional areas for purposes of assisting
which hydrogeologic setting information is combined with
federal, state, and local officials to identify and prioritize areas
rankingorscoringofhydrologicfactors,andassessmentsusing
where more detailed assessments are warranted, to design and scoring methods applied without reference to the hydrogeo-
locate monitoring systems, and to help develop optimum
logicsetting.Thegroupsarenotexclusivebutoverlap.Eachof
groundwater management, use and protection policies. How- these methods produces relative, not absolute, results whether
ever, some of these methods are independent of the size of the
or not it produces a numerical score. Sensitivity analyses can
area evaluated and, therefore, can be used to evaluate the be used as the basis for a vulnerability assessment by adding
aquifer sensitivity and vulnerability of any specific area.
the information on potential point and non-point contaminant
sources.
5.1.2 Hydrogeologic Settings, No Scoring or Ranking—
Hydrogeologic mapping has been widely used to provide
The boldface numbers in parentheses refer to a list of references at the end of
this standard. aquifer sensitivity information. This subgroup of methods
D6030 − 96 (2008)
includes those that generally present information as composite outsubdividingtheareaonthebasisofhydrogeologicsettings.
hydrogeologic maps that can be used for multiple purposes. Methods were developed to have universal application and
The maps can be used individually to make a variety of
were intended to be used consistently to provide uniform
land-use decisions or used as a basis for groundwater and results regardless of location. The methods are useful for
aquifer sensitivity evaluations.Although derivative groundwa- applicationsthatrequireaconsistentapproachoverlargeareas,
ter and aquifer sensitivity maps can be prepared, any geologic
however,thesemethodscanbecomplexandmayrequiremuch
or hydrogeologic map could potentially be used to assess unnecessary data preparation. Furthermore, because criteria
sensitivity. In settings where quantitative data are lacking,
selection and ranking are subjective, the final scores may be
hydrogeologic maps can allow the same conclusions, with the
misleading.
same level of confidence, as scoring methods. Hydrogeologic
5.1.4.1 These methods classify a site or region based on a
settings were mapped in detail without scoring or ranking in
ranking or a numerical score derived from hydrogeological
the Denver Colorado, United States area by Hearne and others
information irrespective of the different hydrogeologic settings
(3).
that may be present within the mapped area. Scores are
5.1.2.1 Sensitivity assessments based on hydrogeologic set-
calculatedfromequationsbasedoncriteriaassumedtoapplyto
tings with no scoring or ranking can be used to assess
different geographic areas and different hydrogeologic condi-
groundwateroraquifervulnerabilitybyoverlayinginformation
tions (1,13–14). For example, in South Dakota (15), drilling
on potential point or non-point contamination sources. For
logs and soil survey maps were used to prepare maps based on
example, the sensitivity map included in Ref (3) has been used
hydraulic conductivity which was inferred from the percent
in combination with a series of maps entitled “Land Uses
and thickness of surface organic matter.Attenuation potentials
Which Affect Ground-Water Management” (4) to conduct
of soil in selected Wisconsin counties (16) were mapped based
vulnerability assessments at specific sites within the greater
on soil depth, permeability, drainage class, organic matter
Denver area.
content, pH, and texture.
5.1.3 Hydrogeologic Settings with Ranking or Scoring, or
5.2 Process-Based Simulation Models—These methods for
Both—This group of methods includes those which assess
assessment of groundwater sensitivity and vulnerability use a
groundwater or aquifer sensitivity within or among various
variety of models, each of which simulates some combination
hydrogeologic settings using specific criteria to rank or score
of the physical, chemical, and biological processes that control
areas beneath which the groundwater or aquifers have different
the movement of water and chemicals from land surface
potentials for becoming contaminated. The assessment is
throughtheunsaturatedzonetoandthroughthesaturatedzone.
usually based on two or more hydrogeologic criteria. For
These processes are formulated in terms of equations that are
example, material texture and depth to aquifer are parameters
derived theoretically or empirically. Analytical or numerical
that are commonly used to establish criteria (5-10). Criteria,
techniques are used, usually within a computer program, to
once defined, can then be ranked or scored, or both.
solve the equations. The solutions take the form of predicted
5.1.3.1 Assessing vulnerability from point and
...
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