ASTM D6312-17
(Guide)Standard Guide for Developing Appropriate Statistical Approaches for Groundwater Detection Monitoring Programs at Waste Disposal Facilities
Standard Guide for Developing Appropriate Statistical Approaches for Groundwater Detection Monitoring Programs at Waste Disposal Facilities
SIGNIFICANCE AND USE
5.1 The principal use of this guide is in groundwater detection monitoring of hazardous and municipal solid waste disposal facilities. There is considerable variability in the way in which existing regulation and guidance are interpreted and practiced. Often, much of current practice leads to statistical decision rules that lead to excessive false positive or false negative rates, or both. The significance of this proposed guide is that it jointly minimizes false positive and false negative rates at nominal levels without sacrificing one error for another (while maintaining acceptable statistical power to detect actual impacts to groundwater quality (4)).
5.2 Using this guide, an owner/operator or regulatory agency should be able to develop a statistical detection monitoring program that will not falsely detect contamination when it is absent and will not fail to detect contamination when it is present.
SCOPE
1.1 This guide covers the context of groundwater monitoring at waste disposal facilities. Regulations have required statistical methods as the basis for investigating potential environmental impact due to waste disposal facility operation. Owner/operators must typically perform a statistical analysis on a quarterly or semiannual basis. A statistical test is performed on each of many constituents (for example, 10 to 50 or more) for each of many wells (5 to 100 or more). The result is potentially hundreds, and in some cases, a thousand or more statistical comparisons performed on each monitoring event. Even if the false positive rate for a single test is small (for example, 1 %), the possibility of failing at least one test on any monitoring event is virtually guaranteed. This assumes you have performed the statistics correctly in the first place.
1.2 This guide is intended to assist regulators and industry in developing statistically powerful groundwater monitoring programs for waste disposal facilities. The purpose of this guide is to detect a potential groundwater impact from the facility at the earliest possible time while simultaneously minimizing the probability of falsely concluding that the facility has impacted groundwater when it has not.
1.3 When applied inappropriately, existing regulation and guidance on statistical approaches to groundwater monitoring often suffer from a lack of statistical clarity and often implement methods that will either fail to detect contamination when it is present (a false negative result) or conclude that the facility has impacted groundwater when it has not (a false positive). Historical approaches to this problem have often sacrificed one type of error to maintain control over the other. For example, some regulatory approaches err on the side of conservatism, keeping false negative rates near zero while false positive rates approach 100 %.
1.4 The purpose of this guide is to illustrate a statistical groundwater monitoring strategy that minimizes both false negative and false positive rates without sacrificing one for the other.
1.5 This guide is applicable to statistical aspects of groundwater detection monitoring for hazardous and municipal solid waste disposal facilities.
1.6 It is of critical importance to realize that on the basis of a statistical analysis alone, it can never be concluded that a waste disposal facility has impacted groundwater. A statistically significant exceedance over background levels indicates that the new measurement in a particular monitoring well for a particular constituent is inconsistent with chance expectations based on the available sample of background measurements.
1.7 Similarly, statistical methods can never overcome limitations of a groundwater monitoring network that might arise due to poor site characterization, well installation and location, sampling, or analysis.
1.8 It is noted that when justified, intra-well comparisons are generally preferable to their inter-well counterparts b...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6312 − 17
Standard Guide for
Developing Appropriate Statistical Approaches for
Groundwater Detection Monitoring Programs at Waste
1
Disposal Facilities
This standard is issued under the fixed designation D6312; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.4 The purpose of this guide is to illustrate a statistical
groundwater monitoring strategy that minimizes both false
1.1 This guide covers the context of groundwater monitor-
negative and false positive rates without sacrificing one for the
ing at waste disposal facilities. Regulations have required
other.
statistical methods as the basis for investigating potential
1.5 This guide is applicable to statistical aspects of ground-
environmental impact due to waste disposal facility operation.
water detection monitoring for hazardous and municipal solid
Owner/operators must typically perform a statistical analysis
waste disposal facilities.
on a quarterly or semiannual basis. A statistical test is per-
formed on each of many constituents (for example, 10 to 50 or
1.6 It is of critical importance to realize that on the basis of
more) for each of many wells (5 to 100 or more). The result is
a statistical analysis alone, it can never be concluded that a
potentially hundreds, and in some cases, a thousand or more
waste disposal facility has impacted groundwater. A statisti-
statistical comparisons performed on each monitoring event.
cally significant exceedance over background levels indicates
Even if the false positive rate for a single test is small (for
that the new measurement in a particular monitoring well for a
example,1%),thepossibilityoffailingatleastonetestonany
particular constituent is inconsistent with chance expectations
monitoring event is virtually guaranteed. This assumes you
based on the available sample of background measurements.
have performed the statistics correctly in the first place.
1.7 Similarly, statistical methods can never overcome limi-
1.2 This guide is intended to assist regulators and industry
tations of a groundwater monitoring network that might arise
in developing statistically powerful groundwater monitoring
duetopoorsitecharacterization,wellinstallationandlocation,
programs for waste disposal facilities. The purpose of this
sampling, or analysis.
guide is to detect a potential groundwater impact from the
1.8 It is noted that when justified, intra-well comparisons
facility at the earliest possible time while simultaneously
aregenerallypreferabletotheirinter-wellcounterpartsbecause
minimizing the probability of falsely concluding that the
they completely eliminate the spatial component of variability.
facility has impacted groundwater when it has not.
Due to the absence of spatial variability, the uncertainty in
1.3 When applied inappropriately, existing regulation and
measured concentrations is decreased, making intra-well com-
guidance on statistical approaches to groundwater monitoring
parisonsmoresensitivetorealreleases(thatis,falsenegatives)
often suffer from a lack of statistical clarity and often imple-
and false positive results due to spatial variability are com-
mentmethodsthatwilleitherfailtodetectcontaminationwhen
pletely eliminated.
itispresent(afalsenegativeresult)orconcludethatthefacility
1.9 Finally, it should be noted that the statistical methods
has impacted groundwater when it has not (a false positive).
described here are not the only valid methods for analysis of
Historicalapproachestothisproblemhaveoftensacrificedone
groundwatermonitoringdata.Theyare,however,currentlythe
type of error to maintain control over the other. For example,
most useful from the perspective of balancing site-wide false
some regulatory approaches err on the side of conservatism,
positive and false negative rates at nominal levels. A more
keepingfalsenegativeratesnearzerowhilefalsepositiverates
complete review of this topic and the associated literature is
approach 100%.
2
presented by Gibbons (1).
1.10 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock
standard.
and is the direct responsibility of Subcommittee D18.21 on Groundwater and
Vadose Zone Investigations.
Current edition approved Jan. 1, 2017. Published January 2017. Originally
ɛ1 2
approved in 1998. Last previous edition approved in 2012 as D6312 – 98 (2012) . The b
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D6312 − 98 (Reapproved 2012) D6312 − 17
Standard Guide for
Developing Appropriate Statistical Approaches for
Groundwater Detection Monitoring Programs at Waste
1
Disposal Facilities
This standard is issued under the fixed designation D6312; 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
ε NOTE—Editorial changes were made throughout in February 2012.
1. Scope Scope*
1.1 This guide covers the context of groundwater monitoring at waste disposal facilities. Regulations have required statistical
methods as the basis for investigating potential environmental impact due to waste disposal facility operation. Owner/operators
must typically perform a statistical analysis on a quarterly or semiannual basis. A statistical test is performed on each of many
constituents (for example, 10 to 50 or more) for each of many wells (5 to 100 or more). The result is potentially hundreds, and
in some cases, a thousand or more statistical comparisons performed on each monitoring event. Even if the false positive rate for
a single test is small (for example, 1 %), the possibility of failing at least one test on any monitoring event is virtually guaranteed.
This assumes you have doneperformed the correct statisticstatistics correctly in the first place.
1.2 This guide is intended to assist regulators and industry in developing statistically powerful groundwater monitoring
programs for waste disposal facilities. The purpose of this guide is to detect a potential groundwater impact from the facility at
the earliest possible time while simultaneously minimizing the probability of falsely concluding that the facility has impacted
groundwater when it has not.
1.3 When applied inappropriately, existing regulation and guidance on statistical approaches to groundwater monitoring often
suffer from a lack of statistical clarity and often implement methods that will either fail to detect contamination when it is present
(a false negative result) or conclude that the facility has impacted groundwater when it has not (a false positive). Historical
approaches to this problem have often sacrificed one type of error to maintain control over the other. For example, some regulatory
approaches err on the side of conservatism, keeping false negative rates near zero while false positive rates approach 100 %.
1.4 The purpose of this guide is to illustrate a statistical groundwater monitoring strategy that minimizes both false negative and
false positive rates without sacrificing one for the other.
1.5 This guide is applicable to statistical aspects of groundwater detection monitoring for hazardous and municipal solid waste
disposal facilities.
1.6 It is of critical importance to realize that on the basis of a statistical analysis alone, it can never be concluded that a waste
disposal facility has impacted groundwater. A statistically significant exceedance over background levels indicates that the new
measurement in a particular monitoring well for a particular constituent is inconsistent with chance expectations based on the
available sample of background measurements.
1.7 Similarly, statistical methods can never overcome limitations of a groundwater monitoring network that might arise due to
poor site characterization, well installation and location, sampling, or analysis.
1.8 It is noted that when justified, intra-well comparisons are generally preferable to their inter-well counterparts because they
completely eliminate the spatial component of variability. Due to the absence of spatial variability, the uncertainty in measured
concentrations is decreased, making intra-well comparisons more sensitive to real releases (that is, false negatives) and false
positive results due to spatial variability are completely eliminated.
1
This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.21 on Groundwater and Vadose
Zone Investigations.
Current edition approved Feb. 15, 2012Jan. 1, 2017. Published December 2012January 2017. Originally approved in 1998. Last previous edition approved in 20052012
ɛ1
as D6312 – 98 (2005).(2012) . DOI: 10.1520/D6312-98R12E01.10.1520/D6312-17.
*A Summary of Changes section appears at the end of this standard
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