Monday
August 24, 19©7
Part VII
Environmental
Protection Agency
40 CFR Part 264
Statistical Methods for Evaluating
Ground-Water Monitoring Data From
Hazardous Waste Faculties; Proposed
Rule
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•1948
federal R.-uiit
jLJ^j^l_Aug'-'st 24. IQ87 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 264
[FRL-3213-1]
Statistical Methods for Evaluating
Ground-Water Monitoring Data From
Hazardous Waste Facilities
AQEKCY: Environmental Protection
Agency.
ACTION: Proposed rule.
SUMMARY: EPA promulgated regulations
for detecting contamination of ground
water at hazardous waste land disposal
facilities under the Resource
Conservation and Recovery Act of 1976
(RCRA). The statistical procedures used
to evaluate the presence of
contamination have been subject to
criticism and require improvement.
Therefore. EPA today proposes to revise
these statistical procedures and requests
comments from the public to assist in
the regulatory development process.
DATE Written comments should be
submitted on or before October 23,1987.
ADDRESSES: The original and two copies
of comments on this proposal should be
mailed to the Docket Clerk, Office of
Solid Waste (WH-S62), U.S.
Environmental Protection Agency, 401M
Street SW.. Washington. DC 20460. The
docket is open from 9:00 to 4:00 Monday
through Friday, except for Federal
holidays. The docket number for thit
rule is F-37-SGWP-FFFFF. The public
must make an appointment to review
docket materials. Call (202) 475-9327 for
appointments. The public may copy a
maximum of SO pages of material from -
any one regulatory docket at no cost.
Additional copies coat $.2O/page,
The official docket for this regulation.
including comments received fay the
Agency, is located in Room MLG lOOfc
U.S. Environmental Protection Agency,
401M St. SW., Washington, DC 20460.
FOR FURTHER INFORMATION CONTACT:
For general information contact: RCRA/
Superfund Hotline, Office of Solid
Waste (WH-S63C). U.S. Environmental
Protection Agency, 401M Street SW.,
Washington. DC 20460, telephone (8001
434-9348, or (202) 382-3000. For
technical information contact James
Brown, (202) 382-4658.
SUPPtEMENTARY INFORMATION:
Preamble Outlino
I. Authority
II. Background
A. Concerns About Existing Standards
B. Suggested Changes Published in ANPRM
C. Public Comments on ANPRM
III. Today's Proposal
A. General Performance Standards
B. Basic Statistical Procedures and
Sampling Schemes
C. Effects of Proposed Changes on Existing
Monitoring Programs
1. Detection Monitoring
2. Compliance Monitoring
IV. Regulatory Analysis
A. State Authority
B. Regulatory Impact Analysis
C. Regulatory Flexibility Act
List of Subjects
I. Authority
These regulations are issued under the
authority of sections 1006, 2002(a), 3004,
and 3005 of the Solid Waste Disposal
Act (SWDA), as amended by the
Resource Conservation and Recovery
Act of 1976 (RCRA), as amended (42
U.S.C. 6905, 6912(a), 6924, and 6825).
II. Background
Subtitle C of the Resource
Conservation and Recovery Act of 1978
(RCRA) creates a comprehensive
program for the safe management of
hazardous waste. Section 3004 of RCRA
requires owners and operators of
facilities that treat, store, or dispose of
hazardous waste to comply with
standards established by EPA that ate
"necessary to protect human health and
the environment." Section 3005 provides
for implementation of these standards
under permits issued to. owners and
operators by EPA or authorized States.
Section 3005 also provides that owners
and operators of existing facilities that
apply for a permit and comply with.
applicable notice requirements may
operate until a permit determination is
made. These facilities are commonly
known as "interim status" facilities.
Owners and operators of interim status
facilities also must comply with
standards set under section 3004.
EPA promulgated ground-water
monitoring and response standards for
permitted facilities in 1982 (47 FR 32274,
July 26,1982), codified in 40 CFR Part
264, Subpart F. These standards
establish programs for protecting ground
water from releases of hazardous
wastes from treatment, storage, and
disposal units. Facility owners and
operators are required to sample ground
water at specified intervals and to use a
statistical procedure to determine
whether or not hazardous wastes or
constituents from the facility are
contaminating ground water. As
explained in more detail below, the
Subpart F regulations EPA promulgated.
in 1982 have generated criticism^ EPA is
today proposing to amend these
regulations to respond to thesa
concerns.
A. Concerns About Existing Standards
The current Part 264 regulations
provide that the Cochran's
Approximation to the Behrens Fisher
Student's t-test (CABF) or an alternative
statistical procedure approved by EPA
be used to determine whether there is a
statistically significant exceedance of
background levels, or other allowable
levels, of specified hazardous waste
constituents. Although the existing 40
CFR Part 264 regulations have always
provided latitude for the use of an
alternate statistical procedure, concerns
have been raised that the CABF
statistical procedure in the current
regulations may not be appropriate. It
has been pointed out that: (1) The
replicate sampling method is not
appropriate for the CABF procedure, (2}
the CABF procedure does not
adequately consider the number of
comparisons that must be made, and (3)
the CABF does not control for seasonal
variation. Specifically, the concerns are
that the CABF procedure could result in
"false positives" (Type I error), thus
requiring an owner or operator
unnecessarily to collect additional
ground-water samples, to further
characterize ground-water quality, and
to apply for a permit modification,
which is then subject to EPA'review. In
addition, there is concern that the CABF
may result in "false negatives" (Type II
error), i.e. instances where actual
contamination goes undetected. This
may occur when the background data,
which are used as the basis of the
statistical comparisons, are highly
variable due to temporal, spatial,
analytical, and sampling effects.
B. Suggested Changes Published in
ANPRM
As a result of these concerns, EPA is
proposing to change both the statistical
procedure and the sampling
requirements of the regulations, by
requiring that owners or operators more
completely characterize the
hydrogeology at the facility, and
including in the regulations performance
standards which the statistical
procedures and the sampling methods
must meet. Statistical procedures and
sampling methods meeting these
performance standards would have a
low probability of indicating
contamination when it is not present
and of failing to detect contamination
that actually is present The facility
owner or operator would have to
demonstrate that a procedure is
appropriate for the conditions at that
facility and ensure that it meets the
performance standard outlined below.
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In addition EPA has outlined several
sampling methods and types of
statistical procedures that the Agency
believes will meet the performance
standards.
EPA recognizes thai the selection of
appropriate monitoring parameters is
also an essential part of a reliable
statistical evaluation. The Agency
addressed this issue in a previous
Federal Register notice (51 FR 26632;
July 24, 1986).
In an advance notice of proposed
rulemaking (ANPRM) issued August 20
1986 (51 FR 29182). EPA solicited
information that would help evaluate
approaches to determining if a facility is
contaminating the ground water. The
Agency requested comments on the
following performance standards that it
was considering:
1. The procedure^} and sampling
requirements isast be protective of
human health and the eavironmeat
2. The owner « operator must
determine the statistical distribution of
each parameter or constituent listed in
the facility permit. The statistical
procedure(s) must be appropriate for the
distribution. The owner or operator
could demonstrate that the distributions
of constituents differ and, thus, more
than one procedure is needed at a
facility.
3. The procedure^) should have a low
probability of Indicating contamination
when it is not present and of failing to
detect contamination that is actually
there. The owner or operator should
consider different numbers of sample
points for different constituents or
procedures.
4. The procedure(s) should be
appropriate for the hydrogaologic setting
and the physical layout of the ground-
water monitoring system.
5. The owner or operator should
describe how observations twtawthe
detection limtt witt b* handled in th»
procedai«(s).
6. Tha owner or operator should
consider, or contra) far, seasonal aid
spatial variability and temporal
correlation in developing the
procedure(s).
In addition. EPA identified certain
statistical procedurw that were
expected to meet these performance
standards and asked for available data
on the following: . .
1. How will the statistical procedures
meeting the performance, standards
perform in actual practice?
2. How sensitive will the procedures
be to different distributioHa?
3. Are data available for EPA to use to
determine Type H error levels for the
procedures in light of the fact that Type
I error (indicating contamination when it
is not present) is closely related to Type
II error (missing existing contamination).
4. Are there other statistical
procedures or sampling requirements
that minimize both Type I and Type II
errors? Are there data showing the
number of Type II errors expected under
any alternate statistical procedure or
- sampling scheme?
5. Are there modeling or measurement
techniques that make it possible to
determine the flow path of the ground
water from an upgradient well to a
particular downgradient well, or to
several adjacent downgradient wells?
8. Does transforming data to its
logarithm or square root improve
conformance to assumptions of a
statistical procedure or are there
appropriate procedures for
untransformed data?
7. If EPA uses a simple comparison of
mean concentrations rather than a
statistical procedure, would this have
acceptable Type I and Type E error-
levels?
8. What Type land Type IIem>r
levels result for the identified
procedures when concentrations of
constituents are below the detection
limit? What error levels would result fer
other procedures?
9. Ground-water monitoring data may
be autocorrelated (i.e.. variation in
monitoring parameters may be
correlated). Is there informatioa on the
degree of autocorrelation at facilities
and appropriate correction* such aa
adjusting the degree* of freedom of
statistical tests or procedures that might
be more-appropriate for autocotreiated
data?
10. Are intra-weli comparisons
appropriate for new facilities?
11. la there available information that
could be used to evaluate the frequency
control comparison and to datafaina am
acceptable range for them?
C. Public Comments on ANPRM
No new data or informatioa were
supplied by cpmmenters in response to,
these 11 specific questions. However,
commenters expressed several coneerna
with the six proposed performance
standards. One concern was that some
of the items In the ANPRM may not
really be performance standards for
statistical procedures. For example;
numbers 1 and 4 are goals appropriate
to the entire ground-water monitoring
effort not just to determine the
appropriateness of the statistical
procedures. Numbers. 2 and & were •
thought to be specific requirements that
the owner/operator must meet to
develop an acceptable procedure, rather
than broad performance standards.
Finally, the two items that would
usually be construed aa specifying
performance of a statistical procedure*
numbers 3 and a. were thought to be too
general for a procedure to meet One
commenter suggested that the section on
performance standards be changed to
evaluation criteria few deteR«min» fee
acceptability of a statistical test«
procedure.
A consensus of respondents said that
performance standards should be
specific, yet flexible. Further, they
should be site-specific to allow for the
unique character of a site to be
considered in defining the standard.
Another area of consensus wa* that
performance standards shoald provide a
"systems" approach to ground-water
monitoring. That is. the performance
standards should address the adequacy
of the site characterisation, &e aiunbar
and siting of monitoring weiJa, the
samp ling frequency aod tecfaEJque, tha-
laboratory analytical matfcods, and-the
statistical analysis of the data. All of
these components interact to determine
the adequacy of a ground-water
monitoring methodology to protect
human, health ari^ the; environment.
Several commenter* felt that the last
performance standard* pertaining to
seasonal and spatial variability, should
be considered in developing &»
statistical procedures and not just
during the data analysis. Consequently.
EPA feels that a performance standard
must incorporate aspects of ground-
water monitoring in addition to the
statistical techniques.
While some respondents- called lor the
performance standards, to specify
requirements, few suggested what those
specific requirements ihnijlH be. The
only specific suggestion made waa that
the Type I error should be set at OJtt. •
However, the context of that comment
made it clear that 0.01 was merely in
preference to 0.05. and tBat selection
was based cm tfa* dc*ir» to kwp tfa*
false positive rate aa low aa possible.
One suggestion was. that riak be
considered in setting performance
standards and that the cast of meeting
the performance requiresncota fhmild be.
taken into arj^ynt. It was aha
suggested that the level of performance
to be required wax a matter far policy
decision by EPA. The reqaiiad level of
perfccmance-ahaufatie beted on what ia
perceived as technically achievable, and
which would result in an acaeptable risk
level. The achievement of zero risk waa
thought- to .beaa-uaaitainable. idealized
goal
In general, the raspo&dfiBte endorsed
the concept oŁ a fMxfbnuaaca standard.
but they provided little in the way of
concrete suggestions as to what the
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Federal Register / Vol. 52, .Vo. 163 / Monday. August 24. 1987 / Proposed Rules
performance standards should be. They
raised many concerns, but suggested
few answers. Some of the requests
contradict others, making it evident that
no single standard can satisfy all of the
comments.
HI. Today's Proposal
In today's proposal, EPA has elected
to retain the idea of general
performance requirements that the
regulated community must meet. This
proposal allows for flexibility in
designing statistical procedures to site-
specific considerations.
EPA has tried to bring a measure of
certainty to today's regula tions while "
accommodating the unique nature of
many of the regulated units in question.
Consistent with this general strategy,
the Agency ia establishing several
options for the sampling schemes and
statistical tests to be used in detection
monitoring and, where appropriate, in
compliance- monitoring.
The Regional Administrator will
specify for each of the hazardous
constituents one or more of the •
statistical tests and sampling schemes
described in today's regulations. In
deciding which statistical test is
appropriate, he will consider the
theoretical properties of the test/the
data available, and the hydrogeology of
the site.
The Agency recognizes that there may
be situations where the statistical tests
and sampling schemes specified may not
be appropriate. In such cases, it is
necessary to develop procedures that
are tailored to the specific performance
standards that every procedure must
meet. Thus, today's regulations establish
• performance standards for use by the
Regional Administrator in determining
whether an alternative procedure or
scheme will be sufficiently protective of
human health and the environment
A. General Performance Standards •
EPA's basic concern in establishing-
today's performance standards for '
statistical procedures is to achieve a
proper balance between the risk that the
procedures will falsely indicate that a
regulated unit is causing background
values or concentration limits to be
exceeded (false positives) and the risk
that the procedures will fail to indicate
that background values or concentration
limits are being exceeded {false
negatives). Today's proposal is designed
to address that concern directly. Thus,
any statistical test or sampling scheme.
whether specified in today's regulations--
or an alternative to those specified.
should meet the folio wing performance
standards:
1. If the distributions differ among
constituents, more than one procedure
may be needed. The owner or operator
must show that the normal distribution
is not appropriate if using a statistical
procedure which assumes the data are
not normally distributed. A "goodness of
fit" test should be used to demonstrate
that the distribution assumptions are not
violated.
2. The statistical test is to be
conducted separately for each
hazardous constituent. At each time that
a test is done, the test for individual
constituents shall be done at a Type I
error level no less than 0.01. A multiple
comparisons procedure may be used to
control the experimentwise error rate at
a level no less than 0.05. However, the
individual well comparisons must have
a Type I error no less than 0.01, which
may make the experimentwise error rate
greater than 0.05. The owner or operator
must evaluate the power and may be
required to increase the sample size to
achieve an acceptable power level. The
sample size and sampling procedure
shall be appropriate to the level of the
Type I and Type II errors and the
decision criteria.
3. The monitoring, well system should
be in accordance with the natural
features of the site. The owner or
operator must ensure that the number,
locations, and depths of wells will
detect hazardous waste constituents
that migrate from the waste
management area to the uppermost
aquifer at the first sampling period after
such migration occurs.
4. The statistical procedure should be
appropriate for the behavior of the
parameters involved. It should include
methods for handling data below th«-
limit of detection. In cases where there
is a high proportion of values below
limits of detection, the owner or
operator may demonstrate that an
alternative procedure is more
appropriate.
5. The statistical procedure should
consider, and if necessary control or
correct for, seasonal and spatial
variability and temporal correlation in
the data.
In referring to "statistical procedures'*.
EPA means to emphasize that the
concept of "statistical significance"
must be reflected in several aspects of
the monitoring program. This involves
not only the choice of a level of
significance, but also the choice of a
statistical test the sampling
requirements, the number of samples,
and the frequency of sampling. Since all
of these interact to determine the ability
of the procedure to detect
contamination, the statistical- procedures
must be evaluated in their entirety, not
by individual components.
A set of specific numerical
performance standards that would.
achieve the proper balance between
false positives and false negatives is not
possible due to site specific differences.
The probability of correctly deciding
that a regulated unit is contaminating
ground water (often expressed as the
power of a statistical test) cannot easily
be summarized by a single number
because the power of a test is related to
the magnitude of the difference between
two populations. Today's regulations do
not attempt to express the idea- of
"exceeding background values or
concentration limits" in terms of any
minimum magnitude. This is because
any statistically significant increase is a
cause for concern. A performance
standard related to the power of a
statistical test would have to be
specified for every possible minimum
magnitude that might be of concern.
This is not feasible given the-current
state of knowledge about ground-water,
contamination.
An alternative would be for EPA to
decide what magnitude of increase it is
concerned about and to specify how
powerful the test would be for that
magnitude of difference. However, the
Agency does not believe it is
appropriate to determine an amount of
contamination that is acceptable foe
each contaminant at each site. Also,
there would remain the problem of
having to specify how powerful the test
should be for values above the minimum
difference of concern. EPA invites
comment on this issue.
B. Basic Statistical Procedures and
Sampling Schemes
Today'a proposed regulations specify
four types of statistical procedures to
detect contamination in. ground water.
EPA believes that at least on» of, these
types of procedure* will-be appropriate
for a wide.variety of situation*. Ta
address situations where these
procedures' may not be appropriate, EPA
has placed a provision in today's..
proposed regulations.for the Regional
Administrator to select an alternate
procedure. The suggested procedure*
are based in part on suggestions-
received in public comments.
1. A parametric analysis of variance
(ANOVA) followed by multiple
comparison procedures to identify
specific sources of difference. The
procedures will include estimation and
testing of the contrasts between the
mean of each downgradlent well and the
upgradient mean for each constituent.
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federal Register / VoLj^o. 163 / Monday. August 24. 1937 / Proposal Rules
31951
2. An analysis of variance (ANOVA)
based on ranks followed by multiple ,
comparison procedures to identify
specific sources of difference. The
procedure will include estimation and
testing of the contrasts between the
median of each downgradient well and
the median upgradient levels for each.
constituent.
3. A procedure in which a tolerance or
prediction-interval is established from
the background (upgradient well) data,
and the level of each constituent in each
downgradient well is compared to its
upper tolerance or prediction limit.
4. A control chart approach which
would give control limits for each
constituent. If any downgradient well
has a value outskle the control limits for
that constituent, that would constitute
statistically significant evidesee of
contamination. .
5. Another statistical test procedure
specified by the Regional Administrator,
provided that it is protective of human
health aad the environment and meet*
the performance standards specified.
EPA has specified multiple statistical
and sampling procedures aad haa.
aliowed for alternatives because no one
procedure is appropriate for all
circumstances. EPA believes that the
suggested procedures are appropriate —•
for the site-specific design and analysis
of data from ground-water monitoring
systems, and they can account for more
of the site-specific factors than
Cochran's Approximation to the Behren*
Fisher Student's, t-test (CABF) and the
accompanying sampling procedures in
the current regulation. The statistical
procedures specified in today's
regulations address the multiple
comparison problems and provide fo*
documenting and accounting for source*
of natural variation.
EPA believe* that the specified teats.
consider and control far natural
temporal and spatial variation.
Technical details, and axampiaa Łop each
specified procedure will be included In a
draft guidance document which U.
anticipated to be available by
September. 1987. The decision on the
number of wella needed in a monitoring,
system will be made on a site-specific
basis by the Regional Administrator and
will consider the statisticalmethod
being used, the natural hydrogeology..
and the sampling scheme. The number
of wells must be sufficient to ensure a
high probability of detecting
contamination when it is present. To.
determine whiqh sampling, scheme
should be used, the Regional
Administrator should consider existing
data and site characteristics including
the possibility of trends and seasonality.
The regulations establish three sampling
schemes and a provision for an
alternative Tor use in detection and
compliance monitoring systems. These
sampling schemes are:
1. Obtain a sequence of dairy (or
nearly daily) observations at least twice
a year unless it Is found that this
frequency of sampling results in
autocorrelation of the observations.
2. Obtain a sequence of weekly
observations at least twice a year,
provided that weekly observations are
not autocorrelated and that no seasonal
effects, are present in the data.
3. Obtain monthly observations
provided the data exhibit no seasonal
effects.
4. Use another sampling schedule
appropriate to an alternative statistical
procedure specified by the Regional
Administrator. The alternative
procedure must be protective of human
health and the environment.
.EPA believes that the above sampling
schemes will allow the use of statistical
procedures that will accurately detect
contamination, these different sampling
scenarios were chosen to allow for the
unique nature of the ground-water. .-'.'•
systems beneath hazardous waste sites-.
These sampling schemes wiH give
proper consideration to the temporal
variation of and correlation among the
ground-water constituents. The specified
procedures require sampling data from
upgradient wells, at the compliance
point, and according to a specific test
protocol. The owner or operator should
use a background value determined
from data collected under one of these
scenarios if a test specified by the
Regional Administrator requires it or if
a concentration limit in compliance
monitoring is to be based upon
background data. A guidance document
under development Includes scenarios
for which each sampling scheme weald
be appropriate
If the owner or operator uses a
statistical method based on a
distribution other than the nonnai he
must show the normal distribution is not
appropriate. The same applies to
transformations of the data. If the owner
or operator desires to use a
transformation, it must first be shown
mat the untransformed data are
Inappropriate for a normal theory test.
There are several procedures for doing
this, some of which will be detailed nt
the draft guidance document. If
contamination is detected by one of
these tests and the owner or operator-
suspects that the detection is an artifact
caused by some feature of the data other
than contamination, the Regional
Administrator may specify that
statistical tests of trend, seasonal
variation, autocorrelation, or other
interfering aspects of the data be
performed in order to establish whether
the result indicates genuine
contamination or whether the resdt
arose from natural variation.
EPA recognizes that even where the
distribution of a constituent is expected
to be normally distributed, there may be
situations where the owner or operator
can devis* sampling procedures that are
more appropriate to the facility and
which will provide reliable results.
Therefore, today's regulations alk>w the
Regional Administrator to approve such
procedures if he finds that the
procedures balanca the risk of false
positives and false negatives ia a
manner comparable to that provided by
the -above specified tesi*.and that they
meet ths specified performacca
standards, in sxaiaiaiog the
comparability of the suggested
procedure, the Regional Admiaistrator
will examine the ab&t? of the-pwcedura
to provida a reasenaWa balance
between the risk ef false positives and
false negatives. The Regional
Administrator wiB specify, in the permit
such thfngs as th« sampling fivquencjr
and the sampte size for the «hernative
statistical procedure. ' "'"
The regulations indicate &at the
procedure must provide reasonable
confidence that the migration.of
hazardous constituents from a regulated
unit into and through the aquifar will be
detected. (The reference to hazardous
constituents does not mean that this
option applies only to compliance
monitoring; the test also applies te
monitoring parameters aad constituents-
in the detection monitoring program
since they are surrogates indicating the
presence of hazardous constituents.)
The protocols for the specific tests,
however, will be used as a general
benchmark to define "reasonable
confidence" In the proposed procedure.
If the owner or operator shows that his-
suggested teat is comparable hi its-
result* to one of the specified tests-, then
it is Hkely to be acceptable under the
"reasonably confidence-" test. There
may be situations, however, where it
will be difficult to dtireeHy compare the
performance of an alternative test te the
protocofs for the specified1 tests-. In such
cases the alternative te«t w^J have te be
evaluated on its own merits-.
A situation that will probably require
the crafting of a specialized procedure is
the one m which the background level of
a constituent either is below the
detection limit of the analytical methods
used or is recorded as a trace level of
the constituent EPA believes that
appropriate statistical procedures can
be developed m such cases. BPA seeks
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Federal Register / Vol. 52. No. 183 / Monday, August 24, 1987 / Proposed Rules
comments from the public on what
methods are available that rely on
facility-specific data and properly
applied statistical methodologies.
C. Effects of Proposed Changes on
Existing Monitoring Programs
1. Detection Monitoring
The detection monitoring program
relies on the finding of increases over
background levels to define when a
regulated unit is leaking. In addition, in
many situations, the concentration limit
for a particular hazardous constituent
may be set at the background
concentration. Today's proposed
regulations are designed to ensure that
reasonable methods are available for
the analysis of background ground
water quality and for determining if a
specific ground water standard is
exceeded.
The concentration of chemical
constituents in ground water may
fluctuate substantially over time. During
different times of the year the recharge-
rates to ground water will vary.
reflecting the differences in climate,
rainfall, and other factors. Differing
recharge rates or other factors may •
cause seasonal variation in the
concentrations of chemical constituents
in ground water.
EPA believes that such variation in
background concentrations should be
• documented and considered in the
statistical test if it occurs. If such natural
variation in background concentrations
can be documented, a statistical
technique that accounts for such
variation should be used, provided that
this can be done without compromising
other regulatory objectives.
For detection monitoring, and, where
appropriate, for compliance monitoring,,
today's regulations provide three
different sampling schemes for gathering
ground water data. The Regional
Administrator will specify which
sampling scheme is to be used after
considering the data, the statistical test
to be used, the presence of trends, and
natural temporal variation. The
sampling scheme should be designed so
that the major components of temporal
variability can be characterized.
The different sampling procedures
included in today's regulations enable
the Regional Administrator to specify a
sampling scheme that will allow for
documentation of and adjustment for
natural temporal variabilities. In the
past, the tendency has been to abandon
the sampling scheme and to use an
alternate statistical approach when data
exhibited temporal variability. EPA
believes that in most cases one of the
listed sampling schemes will still be
appropriate in this situation if a
correction factor or data transformation
is applied.
It is possible that hazardous
constituents could already be migrating
downgradient before a facility has
received a permit. EPA does not believe
it is generally appropriate to allow such
contamination to continue to migrate
while the owner or operator collects
background data for one year.
Therefore, EPA will, whenever possible,
rely on whatever reliable background
data is available to establish
background values for the compliance
monitoring program. Our concern is that
data collection should not cause a delay
in characterizing background. Possible
methods which would avoid delays in
characterizing the site would be
sampling schemes 1 or 2.
Occasionally,,additional background
sampling and analysis over time may be
appropriate even where compliance. .
point concentrations exceed upgradient.
concentrations, at a given point in time,
if the Regional Administrator believes it
reasonably, possible that this difference.'
is due to seasonal or spatial variation in
ground water quality. In this case, the
Regional Administrator would consider
whether the rate of ground water flow
(and any contamination] was
sufficiently slow thai additional time for
collection of ground water quality data
would not jeopardize the potential for
successful corrective action if it is
determined to be necessary. The
Regional Administrator would not,
however, allow time for additional data
gathering in cases where the initial
difference in compliance point and
upgradient constituent concentration is
above potential seasonal variation.
The owner or operator who wants to
account for seasonal variations in the
background values has at least three
additional options. One, he can . . ;
anticipate the need foe such data bjs
collecting upgradient data on Appendix.
IX constituents Likely to be in leachate
before the detection monitoring prograa
indicates that leakage haa occurred.
Two, he may continue to collect
background data after the compliance
monitoring program permit is issued-
Three, he may use that data in making a
demonstration that an apparent increase.
over concentration limits in the ground,:
water protection standard was caused '
by contamination from other sources. He
may also use the data in seeking a
permit modification to change the
background values contained in the
compliance monitoring program.
Another issue in the establishment of
background for a constituent is the
question of which wells should be used'
in the data base. In evaluating temporal
variability, the frequency of sampling
and the statistical method used to
analyze the sampling data should be
designed and considered
simultaneously,.
One option, which EPA is considering
for detection monitoring programs at
new facilities and possibly also at
facilities where it is known that ground
water is not contaminated, is to collect
background data by monitoring
downgradient wells. In each
downgradient well, ground-water
concentration levels would be
monitored and the resulting data would
be used to establish a background limit
that would be unique to each
downgradient well. The advantages of
this approach are that first, the influence
of spatial variability would be removed:
second, a control chart class of
statistical thresholds could be
developed for each downgradient well;
and third, upgradient wells may not be
required..The disadvantages are that
first there must be assurance that
contamination-from the unit is not being
factored into establishment of the
background data base, and; second, if
this method! is used and contamination
unrelated to the regulated unit flows
under the downgradient side of the unit
after establishment of the background
limits, a false positive may result.
EPA believes that this method best
applies to newer uni«s that have had no
opportunity; to contaminate the ground
water and that are located in areas with
little potential to be influenced from
external sources unrelated to the unit. It
is also clear that this method can only
be applied the first time a facility is in
detection monitoring. A facility which
begins compliance monitoring and
subsequently returns to detection
monitoring will not be allowed to
establish or reestablish background
limits based on data collected in the
downgradient wells. EPA seeks
comment on the utility of allowing
downgradient'wells to serve as
background in these situations.
A second option, which EPA believes
is preferable in most situations, and
which corresponds to the current
regulatory approach, is to base
background data on upgradient wells.
Assuming these wells are'properly '
placed andtmaffected by the unit they
should produce data that are not biased
by contamination from the unit. :
2. Compliance Monitoring
The statistical procedure(s) that will
be used in compliance monitoring will
be contingent upon the type of
concentration limit used. If the
concentration limit is based upon the
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Federal Register / VoUjZ, No. 163 / Monday, August 24. 1987 / Proposed Rules
31933
background values, then one of the
statistical procedures specified in the
regulations may b'e used. If the
concentration limit is based upon a
maximum concentration limit or an
alternate concentration limit, then the
Regional Administrator will require an
appropriate test. In many cases this is
the tolerance interval procedure
specified in the proposed regulations.
IV. Regulatory Analysis
A. State Authority
Under section 3006 of RCRA, EPA
may authorize qualified States to
administer and enforce their State
hazardous waste management programs
in lieu of EPA operating the Federal
program in those States. Authorization,
either interim or final, may be granted to
State programs that regulate the
identification, generation,
transportation, or operation of facilities
that treat, store, or dispose of hazardous
waste. Upon authorization of the State
program, EPA suspends operation
within the States of those parts to the
ground-water monitoring, requirements
for land-based hazardous waste
management facilities applying for and
operating under permits. Since the
ground-water monitoring requirements
are not imposed under any of the
amendments made by the Hazardous
and Solid Waste Amendments of 1984,
final rules modifying the statistical
procedures would not take effect
directly in all States under section
3006{g). Rather, if EPA promulgates this
proposal. States that have been granted
final authorization will have to revise
their programs to cover the additional
requirements in today's announcement.
Generally, these authorized State
programs must be revised within one
year of the date of promulgation of such
standards, or within two years if the
State must amend or enact a statute in
order to make the required revision. See
40 CFR 271.21. However. States may
always impose requirements which are
more stringent or have greater coverage
than EPA's programs.
Regulations which are broader in
scope, however, may not be enforced as
part of the federally-authorized RCRA
program.
B. Regulatory Impact Analysis
Executive Order 12291 (48 FR13191,
February 9.1981) requires that a
regulatory agency determine whether a
new regulation will be "major" and if so,
that a Regulatory Impact Analysis be
conducted. A major rule is defined as a
regulation that is likely to result im
1. An annual effect on the economy of —
$100 million or more;
2. A major increase in costs or prices
for consumers, individual industries,
Federal, State, or local government
agencie>-or geographic regions; or
3. Significant adverse effects on
competition, employment, investment,
productivity, innovation, or the ability of
United States-based enterprises to
compete with foreign-based enterprises
in domestic or export markets.
Therefore, the Agency has determined
that today's proposal is not a major rule.
Today's action should produce a net
decrease in the cost of ground-water
monitoring at each facility. This
proposal has been submitted to the
Office of Management and Budget
(OMB) for review in accordance with
Executive Order 12291.
C. Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility
Act, 5 U.S.C. 601 et seq., whenever an
agency is required to publish a general
notice of rulemaking for any proposed or
final rule, it must prepare and make
available for public comment a
regulatory flexibility analysis which
describes the impact of the rule orr small
entities (i.e., small businesses, small
organizations, and small governmental
jurisdictions). The Administrator may
certify, however, that the rule will not.
have a significant economic impact on a-
substantial number of small entities. As-
stated above, this proposal will have no
adverse impacts on businesses of any •
size. Accordingly, I hereby certify that
this proposed regulation will not have a
significant economic impact on a
substantiatnumber of small entities.
This regulation therefore does not
require a regulatory flexibility analysis.
List of Subjects in 40 CFR Part 284
Hazardous material. Reporting and
recordkeeping requirements, Waste
treatment and disposal. Ground water,
Environmental monitoring;
Date: August 14,1987.
Lee M. Thomas,
Administrator.
Therefore, it is proposed that 40 CFR
Chapter I be amended as follows:
PART 264—STANDARDS FOR
OWNERS AND OPERATORS OF
HAZARDOUS WASTE TREATMENT,
STORAGE, AND DISPOSAL
FACILITIES
1. The authority citation for Part 264
continues to read as follows:
Authority: Sees. 1006,2002(a). 3004. and
3005 of the Solid Waste Disposal Act. as
amended by the Resource Conservation and
Recovery Act as Amended (42 U.S.C. 6905,
6912(a). 6924, and 6925).
2. In § 264.91 by revising paragraphs
(a](l) and (a)(2) to read as follows:'
§ 264.91 Required program*.
(a) * * *
(1) Whenever hazardous constituents
under § 264.93 from a regulated unit are
detected at the compliance point under
§ 264.95, the owner or operator must
institute a compliance monitoring
program under § 264.99. Detected is
defined as statistically significant
evidence of contamination as described
in § 264.98{e);
(2) Whenever the ground-water
protection standard under § 264.92 is
exceeded, the owner or operator must
institute a corrective action program
under § 264.100. Exceeded is defined as
statistically significant evidence of
increased contamination as described in
§ 264.99(d);
* * « * *
3. Section 284.92 is revised to read as
follows:
§264.92 Ground-water protection
standard
The owner or operator must comply
with conditions specified in the facility
permit that are designed to ensure that
hazardous constituents under § 264.93
detected in the ground water from a
regulated unit do not exceed the
concentration limits under § 284.94 in
the uppermost aquifer underlying the
waste management area beyond the
point of compliance under § 264.95
during the compliance period under
§ 264.96. The Regional Administrator
will establish this ground-water
protection standard in the facility permit
when hazardous constituents have been
detected in the ground water.
4. In § 284.97 by removing the word
"and" from the end of (a)(l), adding
(a)(l)(i) and (a)(3), revising paragraphs
(g) and (h>, and adding (i), (j), and (k) to
read as follows:
1264.97 General ground-water monitoring
requirements.
(a) * *
(1) * * *
(i) A determination of background
quality may include sampling of wells
that are not upgradient from the waste
management area where:
(A) Hydrologic conditions do not
allow the owner or operator to
determine what wells are upgradient;
and
(B) Sampling at other wells will
provide an indication of background
ground-water quality that is
representative or more representative
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Federal Register / Vol. 52. N'o. 153 / Monday, August 24, 1987 / Proposed Rules
than that provided by the upgradient
wells;-and
(3) Provide statistically significant
evidence that hazardous waste or
hazardous constituents that migrate
from the waste management area to the
uppermost aquifer will be detected.
• • » • *
(g) In detection monitoring or where
appropriate in compliance monitoring,
data on each hazardous constituent
specified in the permit will be collected
from background wells and wells at the
compliance point(s). The sampling
procedures and frequency must be
protective of human health and the
environment. The sampling
requirements must ensure that the
statistical procedure has an acceptably
low probability of failing to detect
contamination. The Regional
Administrator will specify one or more
of the following requirements in the
permit for each hazardous constituent to
be monitored fan
(1) Obtain a sequence of dairy (or near
daily) samples at least twice a year,
unless it is found that this- frequency of
sampling results in autocorrelation of
the observations that cannot be
corrected by the statistical procedure
used.
(2) Obtain a sequence of weekly
samples at leasl twice a year, provided
that weekly observations are not
autocorrelated and that no seasonal •
effects are present in the data osed in
each periodic comparison.
(3) Obtain monthly samples provided'
the data exhibit no seasonal effects.
(4) Use an alternate sampling
procedure specified by the Regional . • '
Administrator under paragraph (i) of
this section.
(h) Based on. the factors in § 2M.9CT{1V
the Regional Administrator will apectfjr
one of the following statistical
procedures to be used in combination. .
with the sampling requirements for each
hazardous constituent:
(1) A parametric analysis of variance
(Af.'OVA) followed by multiple
comparisons procedures to identify
statistically significant evidence-of
contamination. The procedure must
include estimation and testing of the
contrasts between each downgradient
well's mean and the upgradient mean
levels for each constituent
(2) An analysis of variance (ANOVA)
based on ranks followed by multiple
comparisons procedures to identify
statistically significant evidence of
contamination. The procedure must
include estimation and testing of the
contrasts between each downgradient
well's median and the background
median levels for each constituent
(3) A tolerance or prediction interval
procedure in which a tolerance interval
for each constituent is established from
the distribution of the background data.
and the level of each constituent in each
downgradient well is compared to the
upper tolerance or prediction limit.
(4) A control chart approach that gives
control limits for each constituent.
(5) Another statistical test procedure
that is protective of human health and
the environment and meets the
performance standards specified in
§ 264.97{i}.
(i) The Regional Administrator can
establish an alternative sampling
procedure and statistical test for
hazardous constituents that he finds will
be protective of human health and the
environment. In establishing that
procedure, the Regional Administrator ..
will consider the following factors;
(1) If the distributions for differeat-
constituents differ, mote than one •
procedure may be needed. The owner or-
operator must ahavf that the normal
distribution is not appropriate, if using a
nonparametric ox other, methodology not
requiring an assumption of normality.
For any statistic not based on a normal
distribution, a goodness of fit test shall.
be conducted to demonstrate that the
normal distribution is not appropriate.
Other tests shall be conducted to •
demonstrate that the assumptions of tha
statistic or distribution are not grossly.
violated.
(2) Each hazardous constituent is to -,
be tested for separately. At each time
that a test ia done, the test far individual
constituents shall be done at a-Type I
error level no less than 0.01. A multiple
comparisons- procedure- may be need at -
a Type I experimemlwise error rate DO
less than 0.05. The owner or operator .
must evaluate, the ability' of the method,
to detect contamination that is actually -
present and may be required to increase
the sample size to achieve an acceptable
power level.
(3) The monitoring well system should
be consistent with § 264.97{a}. The
owner er operator must ensure.that the -
number, locations, and depths of
monitoring wetts wiH detect hazardous''
constituent* that migrate front the waste
management area to the uppermost •
aquifer.
(4) The statistical procedure should be
appropriate for the behavior of the
parameters involved. It should include
methods for handling data below the
limit of detection.The owner or operator
should evaluate different ways of •- •
dealing with values below the limit of '•
detection and choose the one that is ' •
most protective of human health' and the
environment. In cases where there is a
high proportion of values below limits of
detection, the owner or operator may
demonstrate that an alternative
procedure is more appropriate.
(5) The statistical procedure used
should control for seasonal and spatial
variability and temporal correlation.
(j) Ground-water monitoring data
collected in accordance with paragraph
(gj of this section including actual ^-els
of constituents must be maintained in
the facility operating record. The
Regional Administrator will specify in
the permit when the data must be'
submitted for review.
(k) If contamination is detected by
any of the-statistical tests, and the
Regional Administrator or the owner or
operator suspects that the detection is
an artifact caused by some feature of
the data other than contamination, the
Regional Administrator, may specify that
statistical tests of trend, seasonal
variation, autocorrelation* or other
interfering aspects of the data be done .
to establish whether the significant
result is indicative of detection of-.
contamination, or resulted from natural
variation,
(5). In 1264.93 by removtRg-
paragraphs (i), (j) and (k>, and by
revising paragraphs (c). (d), (f), (g), and
(h) to read as foffowsr
§ 264.98 Detection monitoring program.
* * • *• : •
(c) The owner or operator must " •
conduct a ground-water monitoring
program for each parameter ot \
constituent in accordance with
§ 254.97{gJ. The owner or operator must
maintain a record of ground-water
analytical data as measured and In a
form necessary for the determination of
statistical significance under § 264.9701]
for the active life and post-closure care
period of the facility.
(dj The Regional Administrator will
specify how often the owner or operator
must collect samples and conduct
statistical tests to detect contamination.
The frequencies for both wUl be at least
semi-annually and will be consistent
with § 264.97(g) considering the size of
the Type I or Type II errors. Where
appropriate, the comparison will be
mads between background wells and
wells at the point(s) of compliance.
* • * • - *
(f) The owner or operator mast
determine whether there is statistically
significant evidence of contamination
for any parameter or constituent
specified in the permit pursuant to
paragraph (a) of this section at a
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Federal Register / Vol. 52._No. 163 / .Monday, August 24. 1987 / Proposed Rules
3195S
frequency specified under paragraph (d)
of this section.
(1) In determining whether
statistically significant evidence of
contamination exists, the owner or
operator must use the procedure(s)
specified in the permit under § 264.97(h).
This procedure(s) must compare data
collected at the compliance point(s) to '
the background water quality data.
(2) The owner or operator must
determine whether there is statistically
significant evidence of contamination-at
each monitoring well at the compliance
point within a reasonable period" of time
after completion of sampling. The
Regional Administrator will specify in
the facility permit what period of time is
reasonable, after considering the
complexity of the statistical test-and the
availability of laboratory facilities to
perform the analysis of ground-water
samples.
(g) If the owner or operator
determines pursuant to paragraph (f) of
this section that there is statistically
significant evidence of contamination
for parameters or constituents specified
pursuant to paragraph (a) of this section
at any monitoring well at the
compliance point, he must:
(1) Notify the Regional Administrator
of this finding in writing within seven
days. The notification must indicate
what parameters or constituents have
shown statistically significant evidence
of contamination.
(2) Immediately sample the ground-
water in all monitoring wells at the
waste management area of concern and
determine if there is a statistically
significant difference between the
compliance and background levels for
concentration of all constituents
identified in Appendix IX of Part 264.
(3) For any Appendix IX compounds
for which there is a significant
difference, the owner or operator may
resample within one month and repeat
the Appendix IX analysis for those
compounds detected. If the results of the
second analysis confirm the initial
results then these constituents will form
the basis for compliance monitoring. If
they do not resample, the hazardous
constituents found during the initial
Appendix IX analysis will form the
basis for compliance monitoring.
(4) Within 90 days, submit to the
Regional Administrator an application
for a permit modification to establish a
compliance monitoring program meeting
the requirements of § 264.99. The
application must include the following
information:
(i) An identification of the
concentration of any Appendix IX
constituent detected in the ground water
at each monitoring well at the
compliance point;
(ii) Any proposed changes to the
ground-w_atermonitoring system at the
facility ffecessary to meet the
requirements of § 264.99;
(iii) Any proposed additions or
changes to the monitoring frequency,
sampling and analysis procedures or
methods, or statistical procedures used
at the facility necessary to meet the
requirements of § 264.99;
(iv) For each hazardous constituent
detected at the compliance point, a
proposed concentration limit under
§ 264.94{a) (1) or (2), or a notice of intent
to seek a variance under § 264.94(b); and
(5) Within 180 days, submit to the
Regional Administrator:
(i) All data necessary to justify any
variance sought under § 264.94(6); and
(ii) An engineering feasibility plan for
a corrective action program necessary to
meet the requirements of § 264.100,
unless:
(A) All hazardous constituents
identified under paragraph (g)(2) of this
section are listed in Table 1 of § 264.94
and their concentrations do not exceed
the respective values given in that
Table; or
(B) The owner or operator has sought
a variance under § 264.94(b) for every
hazardous constituent identified under
paragraph (g}(2) of this section.
(6) If the owner or operator
determines, pursuant to paragraph (f) of
this section, that there is a statistically
significant difference for parameters or
constituents specified pursuant to
paragraph (a) of this section at any
monitoring well at the compliance point,
he may demonstrate that a source other
than a regulated unit caused the
contamination or that the contamination
resulted from error in sampling,
analysis, or evaluation. While the owner
or operator may make a demonstration
under this paragraph in addition to, or in
lieu of, submitting a permit modification
application under paragraph (g)(3) of
this section, he is not relieved of the
requirement to submit a permit
modification application within the time
specified in paragraph (g)(3) of this
section unless the demonstration made
under this paragraph successfully shows
that a source other than a regulated unit
caused the increase, or that the increase
resulted from error in sampling,
analysis, or evaluation. In making a
demonstration under this paragraph, the
owner or operator must:
(i) Notify the Regional Administrator
in writing within seven days of
determining statistically significant
evidence of contamination at the
compliance point that he intends to
make a demonstration under this
paragraph;
(ii) Within 90 days, submit a report to
the Regional Administrator which
demonstrates that a source other than a
regulated unit caused the contamination
or that the contamination resulted from
error in sampling, analysis or
evaluation:
(iii) Within 90 days, submit to the
Regional Administrator an application
for a permit modification to make any
appropriate changes to the detection
monitoring program at the facility; and
(iv) Continue to monitor in accordance
with the detection monitoring program
established under this section.
(h) If the owner or operator
determines that the detection monitoring
program no longer satisfies the
requirements of this section, he must,
within 90 days, submit an application
for a permit modification to make any
appropriate changes to the program.
6. In § 264.99 by revising paragraph
(c), revising paragraphs (d), (f), and (g),
removing paragraph (h), redesignating
paragraph (i) as (h), 0) as (i), and (k) as
(i), revising the redesignated paragraphs
(h) introductory text and (i) introductory
text, and removing paragraph (1) to read
as follows:
§264.99 Compliant* monitoring program..
'*****
(c) The Regional Administrator will
specify the sampling requirements and
statistical procedures appropriate for
the constituents and site, consistent
with § 284.97 (g) and (h).
(1) The owner or operator must
conduct a sampling program for each
parameter or constituent in accordance
with 9 264.97(h).
(2) The owner or operator must record
ground-water analytical data as
measured and in a form necessary for
the determination of statistical
significance under 5 264.97(h) for the
active life and post-closure care period
of the facility.
(d) The owner or operator must
determine whether there is statistically
significant evidence of increased
contamination for any parameter or
constituent specified in the permit,
pursuant to paragraph (a) of this section.
at a frequency specified under
paragraph (f) of this section.
(1) In determining whether
statistically significant evidence of
increased contamination exists, the
owner or operator must use the
procedure(s) specified in the permit
under § 264.97(h). This procedure must
compare data collected at the
compliance point(s) to a concentration
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31956
Federal Register / Vol. 52. N'o. 163 / Monday. August 24. 1987 / Proposed Rules
limit developed in accordance with
§ 264.94.
(2} The owner or operator must
determine whether there is statistically
significant evidence of increased
contamination at each monitoring well
at the compliance point within a
reasonable time period after.completion
of sampling. The Regional Administrator
will specify that time period in the
facility permit after considering the
complexity of the statistical test and the
availability of laboratory facilities to
perform the analysis of ground-water
samples.
• • • . .
(f) The Regional Administrator will
specify the frequencies for coaducting
statistical teat* to determine statistically
significant evidence of increased
contamination. The frequencies, will be •
at least semi-annuaUy and wiil bo
consistent with § 2&t97{g) considering-
the size of the Type I and Type ILenrera.
(g) The owner or operator musr
analyze samples from all wells at the
compliance point of a1 regulated unit for
all constituents contained in Appendix
IX of Part 264 et least annually to
determine whether additional hazardous
constituents are present in the upper-
most aquifer, pursuant to procedures m
§ 264.98{f). If the owner or operator finds
Appendix IX constituents in the ground-
water that are not identified in the
permit, the owner or operator may
resample within one month and repeat
the Appendix IX analysis.
If the second analysis confirms the
presence of new constituents, the owner
or operator must report the'
concentration of these additional
constituents to the Regional
Administrator within seven days after
completion of the second analysis and
add them to the monitoring list
(h) If the owner or operator •
determines pursuant to paragraph (dj of
this section that any concentration
limits under § 264.94 are being exceeded
at any monitoring well at the point of
compliance, he must:
*****
(i) If the owner or operator-
determines, pursuant to paragraph (d) of
this section that the ground-water
concentration limits under this section
are being exceeded at any monitoring
well at the point of compliance, he may
demonstrate that a source other than a-
regulated unit caused the contamination
or that the contamination resulted from
error in sampling, analysis, or
evaluation. In making a demonstration
under this paragraph, the owner or
operator must
* * * . »
[FR Doc. 83-19185 Filed 8-21-87; 8:45 am}
BILLtMO CODE 3S80-50-M
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