United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5305W)
EPA530-R-97-055
PB98-108103
November 1997
S.EPA
RCRA, Superfund & EPCRA
Hotline Training Module
Introduction to:
Groundwater Monitoring
(40 CFR Parts 264/265, Subpart F)
Updated July 1997
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DISCLAIMER
This document was developed by Booz-Allen & Hamilton Inc. under contract 68-WO-0039 to EPA. It is
intended to be used as a training tool for Hotline specialists and does not represent a statement of EPA
policy.
The information in this document is not by any means a complete representation of EPA's regulations or
policies. This document is used only in the capacity of the Hotline training and is not used as a reference
tool on Hotline caEs, The Hotline revises and updates this document as regulatory program areas change.
The information in this document may not necessarily reflect the current position of the Agency. This
document is not intended and cannot be relied upon to create any rights, substantive or procedural,
enforceable by any party in litigation with the United States.
RCRA, Super-fund & EPCRA Hotline Phone Numbers:
National toll-free (outside of DC area) (800) 424-9346
Local number (within DC area) (703) 412-9810
National toll-free for the hearing impaired (TDD) (800) 553-7672
The Hotline is open from 9 am to 6 pm Eastern Time,
Monday through Friday, except for federal holidays.
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50272-101
REPORT DOCUMENTATION
PAGE
0 1. REPORT NO.
• EPA530-R-97-055
2.
4. Title and Subtitle
RCRA, SUPERFUND, AND EPCRA HOTLINE TRAINING NODULE: INTRODUCTION TO
GROUNDWATER MONITORING (40 CFR PARTS 264/265, SUBPART F)
5. Report Date
NOVEMBER 1997
6.
7. Author(s)
• 8. Performing Organization Kept. No
9. Performing Organization Name and Address
U.S. EPA
OFFICE OF SOLID WASTE
401 N STREET, SU
WASHINGTON. DC 20460
0 10. Project/Task/Work Unit No.
O
• 11. Contract(C) or Grant(G) No.
0 (C) 68-WO-0039
12. Sponsoring Organization Name and Address
BOOZ-ALLEN & HAMILTON
4330 EAST WEST HIGHWAY
BETHESOA, MARYLAND 20814
13. Type of Report & Period Covered
TRAINING - UPDATED 7/97
14.
15. Supplementary Notes
16. Abstract (Limit: 200 words)
ONE OF A SERIES OF MODULES DEVELOPED AS A TRAINING TOOL FOR HOTLINE SPECIALISTS. PRESENTS THE REQUIEMENTS FOR GROUND-
WATER MONITORING AT INTERIM STATUS AND PERMITTED TREATMENT, STORAGE, AND DISPOSAL FACILITIES. DESCRIBES THE GROUNDWATER
MONITORING CRITERIA FOR INTERIM STATUS AND PERMITTED FACILITIES. EXPLAINS MONITORING WELL PLACEMENT, OUTLINES THE
THREE STAGES OF THE GROUNDWATER MONITORING PROGRAM FOR PERMITTED FACILITIES. THE INFORMATION IN THIS DOCUMENT IS NOT A
COMPLETE REPRESENTATION OF EPA'S REGULATIONS OR POLICIES, IUT IS AN INTRODUCTION USED FOR HOTLINE TRAINING PURPOSES.
17. Document Analysis a. Descriptors
b. Identifiers/Open-Ended Terns
c. COSATI Field/Group
18. Availability Statement
RELEASE UNLIMITED
• 19. Security Class (This Report)0 21. No. of Pages
° UNCLASSIFIED * 26
• 20. Security Class (This Page) * 22. Price
" UNCLASSIFIED * 0.00
(See ANSI-Z39.18)
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
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GROUNDWATER MONITORING
CONTENTS
1. Introduction 1
2. Regulatory Summary 3
2.1 Permitted Facility Groundwater Monitoring 7
2.2 Interim Status Groundwater Monitoring 19
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Groundwater Monitoring -1
1. INTRODUCTION
This module presents the requirements for groundwater monitoring at interim
status and permitted treatment, storage, and disposal facilities (TSDFs) under the
Resource Conservation and Recovery Act (RCRA). The groundwater monitoring
regulations are found in 40 CFR Parts 264/265, Subpart F. TSDFs managing
hazardous waste in certain land-based units are required to implement a
groundwater monitoring program so that releases of hazardous waste from these
units to groundwater are detected and measures are implemented to remediate the
contamination as soon as possible.
The goal of this module is to explain the standards and specific requirements for
groundwater monitoring programs at interim status and permitted facilities. When
you have completed this module you will be able to:
* Describe the groundwater monitoring criteria for interim status and
permitted facilities
• Explain monitoring well placement
• Understand the three stages of the groundwater monitoring program for
permitted facilities.
Use this list of objectives to check your knowledge of this topic after you complete
the training session.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotlir
: topic used for Hotline training purposes.
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2 - Groundwater Monitoring
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 3
2. REGULATORY SUMMARY
The groundwater monitoring regulations in Parts 264/265, Subpart F, are one part of
an overall strategy to reduce the likelihood of environmental contamination
resulting from hazardous waste treatment, storage, and disposal. This strategy
includes restrictions on disposal of untreated hazardous waste, unit-specific
standards for land-based hazardous waste management units, and monitoring
groundwater below these units. The land disposal restrictions program requires the
treatment of hazardous wastes prior to disposal to reduce the mobility or toxicity of
hazardous constituents. The unit-specific standards for land-based hazardous waste
management units seek to prevent the release of hazardous waste to the
environment. Groundwater monitoring is the final link in this strategy to prevent
environmental contamination. Owners/operators of all land-based units must
institute a groundwater monitoring program that is able to detect and characterize
any releases of hazardous waste or hazardous constituents to the groundwater
underlying the facility. Should the other elements of the strategy fail, groundwater
monitoring will detect the release so it can be remedied.
The regulations in Subpart F of Parts 264/265 are general requirements, establishing
performance-based standards that state what a successful groundwater monitoring
program must accomplish; they do not dictate specific technical standards. Each
facility's groundwater monitoring program is unique because no two TSDFs are
exactly the same. Individual groundwater monitoring programs are based on site-
specific conditions, including the underlying geology and hydrology, as well as the
properties of wastes managed on site.
The groundwater monitoring regulations for interim status facilities were
promulgated in the May 19,1980, Federal Register (45 FR 33232) and codified in Part
265, Subpart F. These regulations were designed to supply background data on
facilities before permitting, as well as to act as a warning system to detect any releases
to groundwater prior to permit issuance.
The groundwater monitoring regulations for permitted facilities were promulgated
in the July 26,1982, Federal Register (47 FR 32350) and are found in Part 264, Subpart
F. These regulations pertain to any land-based facility seeking a Part B permit that
received waste after July 26,1982, or that certified closure after January 26,1983. Part
264, Subpart F, establishes a three-stage program designed to detect and remediate
any releases from regulated units.
Although the groundwater monitoring programs in Part 264 and Part 265 are
different, they do have some common technical and environmental performance
standards. The technical standards establish an engineering objective and allow a
permit applicant to develop a design or set of practices to achieve certain goals
established in the groundwater monitoring requirements under Subpart F. The
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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4 - Groundwater Monitoring
environmental performance standards specify limits on the levels of contamination
that may be released into the environment before remediation is required,
Groundwater is water found below the land surface in the zone of saturation,
meaning that part of the earth's crust in which all voids are filled with water. An
important source of groundwater is the aquifer, which is a geologic formation,
group of formations, or part of a formation capable of yielding a significant amount
of groundwater to wells or springs. There are two types of aquifers: confined and
unconfined. Confined aquifers are under pressure, unconfined aquifers are not
(Figure 1).
The Subpart F programs protect groundwater that is found in the uppermost
aquifer, which is the water-bearing geologic formation nearest the natural ground
surface (§260.10). Also included in this definition are any and all deeper aquifers
that are hydraulically interconnected-with the uppermost aquifer within the
facility's property boundary. These interconnected aquifers are zones of saturation
that present a potential pathway for contamination to reach human beings (Figure
2)-
Although the statute does not limit EPA's regulatory authority to only the
uppermost aquifer, the groundwater monitoring regulations only require that the
uppermost aquifer be monitored. The groundwater monitoring regulations of
Subpart F do not address other aquifers or any other groundwater resources which
are not in or connected to the uppermost aquifer (§§264.90-264.100 and §§265.90-
265.94). Contamination in such areas can be addressed by other mechanisms such as
authority under RCRA §§3004(u) and (v) (for facilities seeking a permit, codified in
§264.101); RCRA §3008(h) (for interim status facilities); RCRA §7003; the
Comprehensive Environmental Remediation, Compensation, and Liability Act
(CERCLA); the Safe Drinking Water Act; or state or local enforcement authorities.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 5
Figure 1
SCHEMATIC OF CONFINED AND UNCONFINED AQUIFERS
Confined
Aquifer
pressure
raises height
of water
column in well
low permeability
confining layer
permeable
layer
} impermeable
bedrock
confining layer
Unconfined
Aquifer
permeable
layer
impermeable
bedrock
layer
Water Table
Direction of
Groundwater
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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6 - Groundwater Monitoring
Figure 2
SCHEMATICS OF AN UPPERMOST AQUIFER
uppermost
aquifer
hydraulic
conductivity
along fault line
uppermost
aquifer
Water Table
Direction of
Groundwater
The information in this document is not by any means a complete representation of EPA's regulations or policies.
But is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 7'
2.1 PERMITTED FACILITY GROUNDWATER MONITORING
EPA has the authority to require an owner/operator of a TSDF to remediate releases
of hazardous waste or hazardous constituents to the environment All permitted
facilities must comply with Part 264, Subpart F, for releases from solid waste
management units (SWMUs). This module addresses the regulations pertaining to
releases to the uppermost aquifer from regulated units, a subset of SWMUs, See the
module entitled RCRA Corrective Action for a discussion of the regulations that
apply to other types of releases from SWMUs. Facilities with permitted regulated
units — landfills, surface impoundments, waste piles, or land treatment units —
must conduct groundwater monitoring to detect, characterize, and respond to
releases of hazardous waste or hazardous waste constituents into the uppermost
aquifer. There are three stages to the Part 264, Subpart F, groundwater monitoring
and follow-up activities:
* Detection monitoring - to detect if a release has occurred
* Compliance monitoring - to determine if the Groundwater Protection
Standard (GWPS) has been exceeded once a release has occurred
* Corrective action - to remediate a release to the uppermost aquifer.
Section 264.97 sets out the basic requirements that apply to all groundwater
monitoring programs under Part 264, Subpart F. The specific requirements that
apply to each of the three phases of groundwater monitoring are found in §§264.98,
264.99, and 264.100.
APPLICABILITY, WAIVERS, AND EXEMPTIONS
Owners/opera tors of TSDFs with regulated units must comply with the
groundwater monitoring requirements of Subpart F during the active life of the
regulated unit. There are, however, limitations to this applicability, expressed in the
regulations as waivers and exemptions. The owner/operator of a regulated unit is
not subject to Subpart F monitoring regulations if he or she can meet any of the
conditions for a waiver or exemption (§264.90(b)). These waivers or exemptions
apply to units for which any of the following apply:
• The unit is exempt from Part 264 under §264.1 (§264.90(b)(l))
* The unit does not receive free liquids, it is an engineered structure, the unit
has inner and outer containment layers, it has a leak detection system
between containment layers, and the design prevents run-on and run-off
(§264.90(b)(2))
The information in this document is-not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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8 - Groundwater Monitoring
• The land treatment unit is not releasing hazardous constituents to the
environment as determined by the Regional Administrator (RA) (this
exemption applies only during the post-closure period) (§264.90(b)(3))
• The waste pile is designed and operated in accordance with §264.250(c)
• The unit has no potential for migration of liquids from the regulated unit(s)
as certified by a qualified geologist or geotechnical engineer (§264.90(b)(4)).
Owners/operators of regulated units must also conduct ground water monitoring in
accordance with Subpart F during the post-closure period. Post-closure is a period of
time after the active life of the facility during which certain maintenance and
monitoring activities must be conducted in order to ensure that no releases will
occur from the units and to remediate releases from these units. Certain units,
however, are exempt from the groundwater monitoring requirements after closure
if they are able to demonstrate clean closure, which involves removal or
decontamination of all waste, waste residues, contaminated containment system
components, and contaminated subsoils (§264.90(c)(l)). Subpart F cannot be waived
during post-closure care if a detection monitoring program is being conducted under
§264.98 (§§264.90(c)(2)and (3)), or if the facility is conducting groundwater
monitoring during the compliance period. A summary of the §264.90, Subpart F,
groundwater monitoring applicability requirements is given in Figure 3.
GENERAL GROUNDWATER MONITORING REQUIREMENTS
The general requirements for groundwater monitoring programs at permitted
facilities are found in §264.97. These general requirements apply to all three phases
of groundwater monitoring: detection monitoring, compliance monitoring, and
corrective action. A groundwater monitoring program established pursuant to Part
264, Subpart F, must have a sufficient number of monitoring wells, installed at
appropriate locations and depths, to yield water samples that:
• Represent the background conditions of the site (groundwater quality not
contaminated by leakage from an RU)
» Represent the quality of groundwater passing the point of compliance
» Detect any contamination of the uppermost aquifer at the point of
compliance.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 9
Figure 3
SUMMARY OF GROUNDWATER MONITORING
APPLICABILITY REQUIREMENTS
Do not have to comply
with Subpart F
NO
Regulated Unit =
Permitted SI, WP, LTU, or LF that
received waste after 7/26/82
§264.90(a)(2)
YES
I
YES
No liquids, engineered structure, inner/outer
containment, leak detection,
AND
no migration? §264,90(b)(2)
Do not have to comply
with Subpart F after
closure
YES
I
NO
LTU Treatment Zone "Clean?"
§264.90(b)(3)
YES
I
NO
No migration?
§264.90(b)(4)
YES
I
NO
Protected WP?
§264.90(b)(5)
YES
I
NO
Clean Closure?
§264.90{c)
Key
LF - Landfill
LTU - Land Treatment Unit
SI - Surface Impoundment
WP - Waste Pile
I
NO
Facility MUST comply with
Subpart F requirements
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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10 - Groundwater Monitoring
If the facility has more than one regulated unit, the owner/operator has the option
of installing one groundwater monitoring system for the entire waste management
area. The groundwater monitoring system for the entire area can be thought of as
an imaginary line circumscribing the group of regulated units, including liners,
dikes, or barriers forming the containment area for such units, rather than for each
individual regulated unit within the waste management area, provided that
contamination from any of the regulated units can be detected at the point of
compliance (§264.97(b)). Figure 4 shows examples of groundwater monitoring
systems for facilities with multiple regulated units. Groundwater monitoring
system configurations are established on a site-specific basis and are detailed in the
facility permit.
SAMPLING
Groundwater monitoring wells must be properly installed so that samples will yield
representative results. All monitoring wells must be lined, or cased, in a manner
that maintains the integrity of the monitoring well bore hole (§264.97(c)). Poorly
installed wells may give false results.
Consistent sampling and analytical procedures must be implemented to ensure an
accurate representation of the quality of groundwater below the waste management
area (§264.97(d)). At a minimum, there must be procedures and techniques for
sample collection, sample preservation and shipment, analytical procedures, and
chain-of-custody control. Sampling and analytical methods must be appropriate for
groundwater sampling and accurately measure the hazardous constituents being
analyzed. Each time that the groundwater is sampled, a determination of the
surface elevation of the uppermost aquifer needs to be made (§264.97(f)). The
owner/operator must develop an appropriate sampling procedure and interval for
each hazardous constituent identified in the facility's permit. This sampling
procedure must consist of a sequence of at least four samples taken at an interval
that ensures each is an independent sample. The owner/opera tor may use an
alternate procedure if approved by the RA, Requirements and procedures for
obtaining and analyzing samples are detailed in the facility permit, usually in a
Sampling and Analysis Plan.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring -11
Figure 4
EXAMPLES OF GROUNDWATER MONITORING SYSTEMS FOR MULTIPLE
REGULATED UNITS
t
/U
Hazardous Waste
Management Unit A
Hazardous Waste
Management Unit B
'--©--©--©--'
©-©-©--
V
Ul -,— ::::::::,,, MTImlI .„,, ., , __ :
1 .
Hazardous Waste
Management Unit A
©
©
Hazardous Waste
Management Unit B
-©--©-(£>-©
KEY
Limit of Waste Management Area
© Upgradient Weil
Downgradient Well
Groundwater Flow
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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12 - Groundwater Monitoring
STATISTICAL ANALYSIS
The owner/opera tor has a choice of five different statistical methods for evaluating
groundwater monitoring data. The method selected must be appropriate for the
type and distribution of chemical constituents detected or suspected to be present in
the groundwater. The five statistical method options (which are discussed in detail
in §264.97(h)) are:
• Parametric analysis of variance
• Nonparametric analysis of variance based on ranks
« Tolerance or prediction interval procedure
• A control chart approach
• Another statistical test method approved by the RA.
Any statistical method selected under §264.97(h) must comply with the performance
standards under §§264.97(i)(l)-(6). These performance standards were established in
order to ensure that evidence of a statistically significant increase (SSI) in a
hazardous constituent is a true indication of a release and is not due to an error in
data analysis. All groundwater monitoring data collected pursuant to §264.97(g)
must be maintained in the facility Operating record (§264.97(j)). The RA will specify
in the facility's permit when the data must be submitted for review.
STAGE I: DETECTION MONITORING PROGRAM
The goal of a detection monitoring program under §264.98 is to detect and
characterize any release of hazardous constituents from a regulated unit into the
uppermost aquifer. The detection monitoring system must be installed at the point
of compliance and adhere to the basic requirements applicable to all groundwater
monitoring systems in §§264.97(a)(2), (b), and (c). The owner/opera tor must •
monitor for certain indicator parameters and any other specific waste constituents or
reaction products that would provide a reliable indication of the presence of
hazardous constituents in groundwater at the point of compliance (§264.98(a)). The
RA will designate in the facility's permit what constituents or parameters must be
monitored. These constituents and parameters are monitored to detect potential
changes in the groundwater quality above background levels, which represent the
quality of groundwater not contaminated by hazardous waste management activity
at the site. A sequence of at least four samples from each well (both background and
compliance wells) must be collected semiannually and analyzed using the statistical
methods discussed above. The RA will specify the frequency for collecting samples
and for conducting statistical tests. Results from sampling wells at the point of
compliance are then compared to the data on background groundwater quality to
determine if there is any statistical evidence of an increase (increase or decrease in
the case of pH) over background. Statistically significant changes in indicator
parameters may suggest that a release has occurred.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring -13
Using the statistical methods in §264.97(h), the owner/opera tor must determine if
there has been an SSI for any chemical or parameter specified in the permit within a
reasonable period of time after completion of sampling. The RA will specify in the
permit what is considered a reasonable period of time. Evidence of a release is
probable if an SSI has occurred. An SSI usually requires that compliance monitoring
be initiated, unless the owner/opera tor can demonstrate that the SSI was due to an
error in sampling or analysis, statistical evaluation, or natural variations in
groundwater chemistry.
If an SSI does occur, the owner/opera tor must:
• Notify the RA within 7 days indicating which parameter(s) or constiruent(s)
triggered the SSI
• Immediately sample all wells for Part 264, Appendix IX, constituents
(Appendix IX is a list of compounds used to determine the presence of
hazardous constituents in groundwater)
• Determine which Appendix IX constituents are present and at what levels
• Submit an application for a permit modification within 90 days to establish a
compliance monitoring program meeting the requirements of §264.99
• Submit an engineering feasibility plan for a corrective action program within
180 days, and all data necessary to justify any alternate concentration limit
sought under §264.94(b).
If the owner/operator can prove, pursuant to §264.98(g)(6), that the contamination
did not result from his or her regulated unit, or that the SSI is due to an error in
sample analysis or natural variations in groundwater geochemistry, the
owner/operator will be released from the requirements to conduct compliance
monitoring or to submit a permit modification. The owner/operator must be able
to provide adequate supporting documentation to be released from these
requirements. Figure 5 gives an overview of the Detection Monitoring Program.
STAGE II: COMPLIANCE MONITORING PROGRAM
Once it is established that a release has occurred, the owner/opera tor must institute
a compliance monitoring program. The goal of the compliance monitoring
program is to ensure that the amount of hazardous constituents released into the
uppermost aquifer does not exceed acceptable levels. Once those levels are exceeded,
the owner/opera tor must initiate corrective action. The compliance monitoring
program establishes routine monitoring (at least semiannually) to determine if the
GWPS has been exceeded.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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14 - Groundwater Monitoring
Figure 5
SUMMARY: DETECTION MONITORING PROGRAM (§264.98)
Has monitoring revealed
contamination?
NO
Compliance Monitoring
YES
§264.91(a)(4)
§270.14(c)(6)(l)
Detected levels >
GWPS?
Establish background values for parameters or
constituents specified by the RA in the permit
to be used in Detection Monitoring
§264.97(g)
NO
YES
Implement a Detection Monitoring Program:
• Indicator parameters and/or constituents are
measured semiannually
• GW Flow Rate and Direction must be
determined annually
§§264.98(a),(c),(d),(e)
YES
§264.98(g)(6)
Trigger SSI?
NO
YES
§264.98(f)
Demonstrate SSI not from RU
NO
Detected levels >
GWPS?
Key
CM = Compliance Monitoring
CA = Corrective Action
GW = Groundwater
GWPS = Groundwater Protection Standards
RU = Regulated Unit
SSI = Statistically Significant Increase
YES
NO
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 15
Grotmdwater Protection Standard
The GWPS is used to indicate when corrective action is necessary to control plumes
of contamination from regulated units (§264.92). When a facility submits an
application for a permit modification to establish compliance monitoring, the RA
specifies the GWPS in the permit. The GWPS consists of four elements:
• A list of hazardous constituents (§264.93)
• The concentration limits for each of the hazardous constituents (§264.94)
• The point of compliance (§264.95)
« The compliance period during which the GWPS applies (§264,96).
The hazardous constituents identified in the GWPS are those constituents from Part
261, Appendix VIII, which have been detected in the uppermost aquifer and are
reasonably expected to be in or derived from the waste contained in a regulated unit.
Concentration limits are the levels of hazardous waste or hazardous waste
constituents allowed to be present in the groundwater. The concentration levels can
be drawn from one of three sources:
• Background levels
• Maximum concentration limits (MCLs) identified in Table 1 of §264.94(a)(2) if
the background level of the constituent is below the value given in Table 1
• Alternate concentration levels (ACLs) established by the RA under §264.94(b).
The RA will also identify in the permit the compliance period (§264.96) and the
point at which the GWPS applies, known as the point of compliance (§264.95). The
point of compliance is the vertical point at which the owner/operator must monitor
the uppermost aquifer to determine if the GWPS has been exceeded (Figure 6). A
proposed point of compliance is incorporated into the Part B permit as required by
§270.14(c)(3). The compliance period is the length of time during which an
owner/opera tor must conduct compliance or corrective action monitoring, equal to
the active life of the waste management area, including any waste- management
activity prior to permitting and the closure period. This period begins when a
permitted facility begins compliance monitoring. In compliance monitoring, the
owner/operator must determine whether the regulated units are in compliance
with the GWPS at the point of compliance during the compliance period.
The owner/operator must determine whether there is any evidence of increased
contamination for any of the hazardous constituents specified in the permit. This is
accomplished by comparing data on samples collected at the point of compliance to
the concentration limits set in the GWPS. The owner/operator must collect a
minimum of four samples from the background and compliance wells at least semi-
annually during the compliance period (§§264.99(d)-(f)). The RA will specify the
frequency for collecting samples and the statistical method appropriate to determine
if an SSI has occurred. The uppermost aquifer flow rate and direction must also be
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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16 - Groundwater Monitoring
Figure 6
SCHEMATIC OF POINT OF COMPLIANCE
LIMIT OF THE WASTE MANAGEMENT AREA
TWO-DIMENSIONAL POINT OF COMPLIANCE
UPPERMOST AQUIFER
Direction of Groundwater Flow
determined at least annually. The owner/operator must analyze samples from
compliance wells for all Appendix IX constituents at least annually to determine if
any additional constituents are present that are not specified in the permit. If
additional constituents are found, they must be added to the list of constituents to be
monitored.
Appendix IX constituents which are not contained in Appendix VIII of Part 261, may
be included as hazardous constituents into the GWPS of a facility's permit by the
Regional Administrator using the omnibus authority of §270.32(b)(2) and RCRA
§3005(c)(3). For further information on the omnibus authority, see the module
entitled Permits and Interim Status. •
If the GWPS is exceeded, the owner/opera tor must notify the RA in writing within
seven days. The owner/operator must indicate which concentration limits have
been exceeded, submit a permit modification within 180 days to establish a
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring -17
corrective action program, and continue to monitor in accordance with the
compliance monitoring program (§264.99(h)).
If the owner/operator can prove contamination resulted from a source other than
the regulated unit, or that the SSI is due to an error in sample analysis or natural
variations in groundwater geochemistry, he or she must notify the RA in writing
within seven days. The owner/operator must also submit documentation proving
the claim to the RA within 90 days and submit a permit modification within 90 days
to make appropriate changes to the compliance monitoring program. If the
contamination is found to have resulted from a regulated unit, the owner/operator
must initiate Stage III, corrective action. Figure 7 presents an overview of the
Compliance Monitoring Program.
STAGE III: CORRECTIVE ACTION PROGRAM
The goal of the Subpart F corrective action program is to bring regulated units back
into compliance with the GWPS at the point of compliance (§264.100(a)). The
Subpart F corrective action program seeks to accomplish this goal by requiring that
the owner/operator either remove the hazardous constituents or treat them in place
(§264.100(b)). The RA determines the time period by which the owner/operator
must begin corrective action after the GWPS is exceeded (§264.1QO(e)), The specific
measures undertaken to achieve corrective action are also specified by the RA and
will vary with each facility. Examples of corrective measures include excavation,
stabilization, solidification, and source control. An owner/opera tor must also
conduct corrective action to remove or treat in place any hazardous constituents
that exceed the GWPS between the point of compliance and the downgradient
property boundary, and beyond the facility boundary where necessary to protect
human health and the environment (§§264.100(e)(l) and (2)).
Effectiveness of Program
In addition to corrective action, the owner/operator must establish and implement
a groundwater monitoring program to demonstrate the effectiveness of the
corrective action program. This program may be based on the requirements for a
compliance monitoring program under §264.99 (§264.100(d)). A semiannual report
on the effectiveness of the corrective action program is required under §264.100(g).
Duration
Corrective action must commence within a reasonable time period after the GWPS
is exceeded. During the compliance period, corrective action measures must be
continued to the extent necessary to achieve compliance with the GWPS. Once
compliance with the GWPS has been achieved, the owner/operator may reinstitute
a compliance monitoring program. During the compliance period, facilities might
move from compliance monitoring to corrective action, and back again. If the
compliance period ends and corrective action is still being conducted, corrective
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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18 - Groundwater Monitoring
action must continue as long as necessary to achieve the GWPS. The
owner/operator can only terminate the corrective action program when the GWPS
has not been exceeded for three consecutive years (§264,100(f)). If the regulated unit
is still in the post-closure period, the owner/opera tor may then reinstate a detection
monitoring program.
Figure 7
COMPLIANCE MONITORING PROGRAM SUMMARY (§264.99)
• Notify RA
• Monitor and establish concentrations for all
Appendix IX constituents which are detected
• Submit permit modification & engineering
feasibility plan for CA
§264.98{g)
Detection Monitoring
Key
• Establish GWPS (§264.92)
l.ListofHC
2. Concentration Limits of HC
3. Point of Compliance
4. Compliance Period
§264.99(a)
" Implement Compliance Monitoring Program
1. Semiannual monitoring
2. Flow rate and direction annually
3. Appendix IX analysis annually
I
Exceed GWPS?
YES I §264.99(h)
Demonstrate the release
is NOT from a Regulated
Unit?
NO
YES
§§264.99(e)-(g)
§264.99(i)
CA - Corrective Action
GWPS - Groundwater Protection Standards
HC - Hazardous Constituents
NO
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 19
A facility may move from one phase of groundwater monitoring to another
depending on the status of the groundwater quality. This means a facility may
move from:
« Detection to compliance monitoring
• Detection monitoring to corrective action
• Compliance monitoring to corrective action
• Corrective action to compliance monitoring
• Compliance to detection monitoring (a facility can reinstate a detection
monitoring program if it is still in the post-closure period and the compliance
period has ended.
For an overview of the corrective action program and the sequences of the
groundwater monitoring program, refer to Figure 8.
2.2 INTERIM STATUS GROUNDWATER MONITORING
The requirements for groundwater monitoring programs for interim status TSDFs
with regulated units are found in Part 265, Subpart F. This program is designed to
determine the facility's impact on the quality of groundwater in the uppermost
aquifer underlying the facility (§265.90(a)). Part 265, Subpart F, however, does not
contain any provisions for corrective action when a release has occurred. If
corrective action is required at an interim status facility, it will be addressed under
RCRA §3008(h), other cleanup authorities such as RCRA §7003, or in the facility
permit when issued. The interim status groundwater monitoring program requires
an owner/opera tor of a surface impoundment, landfill, or land treatment facility
used to manage hazardous waste to implement a groundwater monitoring program
pursuant to Part 265, Subpart F. These requirements apply to all interim status
facilities which have land-based units (except waste piles), unless the units qualify
for an exemption under §265.1. Interim status waste piles are not subject to Part 265,
Subpart F. The owner/operator can also be exempted by demonstrating that there is
a low potential for migration of hazardous waste or hazardous waste constituents to
drinking water supply wells (§265.90(c)). Owners/operators of surface
impoundments that are used only to neutralize corrosive wastes, and contain no
other hazardous waste, may also qualify for an exemption. The owner/operator
must demonstrate that there is no potential for migration of hazardous wastes from
the impoundment (§265.90(e)).
To comply with Part 265, Subpart F, the owner/operator must install, operate, and
maintain a groundwater monitoring system capable of representing the background
groundwater quality and detecting any hazardous constituents that have migrated
from the waste management area to the uppermost aquifer. Each groundwater
monitoring system must consist of at least one upgradient well and three
downgradient wells. The groundwater monitoring system must meet the
requirements of §265.91 and comply with the requirements of §§265.92-265.94.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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20 - Grourtdwater Monitoring
Figure 8
OVERVIEW OF THE CORRECTIVE ACTION PROGRAM (§264.100)
» Notify HA "
• Submit Permit Modification and
Corrective ActidS Plan
Implement CA " " '
1. Bring RU into compliance
2, Prevent HC from exeeedira GWPS
3. Remove or treat HC in place
Establish and implement
program to demonstrate
effectiveness of CA program
T
§26499(h)
Compliance Monitoring
Corrective Action
§§264.100(a) and (b)
*
§264.99(d)
Report effectiveness to RA
semiannually
T
§264.99(g)
YES
Achieve GWPS?
Key
CA - Corrective Action
CM - Compliance Monitoring
GWPS - Groundwater Protection Standards
HC - Hazardous Constituents
RA - Regional Administrator
RU - Regulated Units
NO
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 21
Under Part 265, Subpart F, there are two types of groundwater monitoring programs:
an indicator evaluation program designed to detect the presence of a release, and a
groundwater quality assessment program that evaluates the nature and extent of
contamination. Figure 9 illustrates groundwater monitoring applicability for
interim status facilities.
GROUNDWATER MONITORING SYSTEM
To determine existing groundwater conditions at an interim status facility, the
owner/operator must install at least one well hydraulically upgradient from the
waste management area. The well(s) must be able to accurately represent the
background quality of groundwater in the uppermost aquifer. The owner/operator
must install at least three wells hydraulically downgradient at the limit of the waste
management area, which are able to immediately detect any statistically significant
evidence of a release.
A separate monitoring system for each management unit is not required as long as
the criteria in §265.91(a) are met and the system is able to detect any release at the
edge of the waste management area.
SAMPLING AND ANALYSIS
Section 265.92 establishes the requirements for the development and
implementation of a groundwater sampling and analysis plan to be followed for all
groundwater monitoring activities. The plan must specify procedures for sample
collection, sample preservation, analytical procedures, and chain-of-custody control
(i.e., point of generation to the lab) (§§265.92(a)(l)-(4)).
Owners/operators must establish concentrations for the three sets of parameters
listed in §265.92(b) in both upgradient and downgradient wells. Sampling for these
parameters must be conducted at the following frequencies:
TYPE TESTING FREQUENCY
first year only after first year
Appendix III Constituents* quarterly no further sampling required
Groundwater Quality quarterly annually
Parameters
(Chloride, Iron, Manganese,
Phenols, Sodium, Sulfate)
Groundwater Contamination quarterly no further sampling required
Indicator Parameters
(pH, Total Organic Carbon,
Total Organic Halogen)
* Part 265, Appendix III is a list of EPA Interim Primary Drinking Water Standards taken from the Safe Drinking Water Act.
Appendix III is used to determine the suitability of an aquifer as a drinking water supply.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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22 - Groundwater Monitoring
Figure 9
APPLICABILITY OF GROUNDWATER MONITORING FOR INTERIM STATUS
FACILITIES
Part 265, Subpart F
Not Required
NO
YES
Alternative
groundwater
monitoring program
(Assessment)
YES
§265.93(d)
Inferim status surface
impoundment,
landfill, or land
treatment unit?
§265,90(a)
YES
Low Migration
Waiver?
§265.90{c)
NO
Statistically significant
increase (SSI) of
indicator parameters
assumed?
§265.90(d)
NO
YES
Neutralization in
surface impoundment
exemption?
§265.90(e)
NO
Facility must comply with
Part 265, Subpart F
§265.91
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 23
Initial background concentrations are established during the first year by monitoring
all wells (upgradient and downgradient) for the three groups of constituents listed
in §265.92(b). After the first year, the owner/operator must continue to monitor all
wells for the groundwater quality parameters and groundwater contamination
indicator parameters. This is known as the indicator evaluation program. The data
on the groundwater contamination parameters collected from downgradient wells
are compared to data on background water quality to determine if any
contamination of the uppermost aquifer has occurred. As discussed earlier,
statistically insignificant changes in the indicator parameters indicate a potential
release. Groundwater elevation must also be determined each time a sample is
taken.
If an owner/operator assumes or already knows that contamination of the
uppermost aquifer has occurred, he or she may initiate an assessment monitoring
program as described below in lieu of an indicator evaluation program (§265.90(d)).
GROUNDWATER ASSESSMENT PROGRAM
In addition to the basic program of at least one upgradient and three downgradient
wells under §265.91, owners/opera tors must prepare an outline of a more detailed
groundwater monitoring program (§265.93). This program must be able to
determine whether hazardous waste or hazardous waste constituents have leached
into the uppermost aquifer in a quantity that would cause a significant change in
groundwater quality. This additional program is often referred to as a groundwater
assessment program. The groundwater assessment program must be implemented
when there has been an SSI (increase or decrease for pH) of an indicator parameter
over background levels. The groundwater assessment program is designed to
determine whether hazardous constituents have entered the groundwater. Once
the owner/operator makes this determination, he or she has to establish the rate,
extent of migration, and the concentrations of constituents in the plume.
Statistically Significant Increase (SSI)
If variations in groundwater quality are detected by evidence of statistically
significant differences in concentrations of any of the indicator parameters between
the downgradient wells and background data, the regulations require the
owner/operator to obtain additional samples (§265.93(c)(2)). If the assessment
monitoring indicates that no hazardous constituents have entered the groundwater,
then the owner/operator may reinstate the basic indicator evaluation program. If
the analyses performed on the second round of samples confirms an SSI, the
owner/operator must notify the RA within seven days. Examples of variations that
would require additional sampling include a significant increase or decrease in pH
or a significant increase in any of the groundwater contamination parameters (e.g.,
total organic carbon) being monitored. Within 15 days after the initial notification, a
written monitoring assessment plan must be developed by the owner/operator and
submitted to the RA. The assessment plan must include the number of
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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24 - Groundwater Monitoring
groundwater monitoring wells, the intended sampling, analytical, and evaluation
procedures, and an implementation schedule. The plan must be designed to
determine the rate and extent of migration of hazardous waste constituents and
their concentration (§265.93(d)(4)). Information gathered from assessment
monitoring must be submitted within 15 days after it is collected.
The owner/operator must repeat the groundwater assessment at least quarterly
until final closure of the facility (§265.93(d)(7)).
An interim status facility's groundwater monitoring program can move from:
• Indicator evaluation to assessment monitoring
* Assessment to indicator evaluation monitoring
» Assessment monitoring through final closure.
To meet the requirements of the groundwater assessment program, an
owner/operator may need to install additional wells at various locations and
depths. Additionally, wells are required to pinpoint the exact location of a
contaminated plume. Schematic examples of the placement of wells for meeting
the requirements of the interim status groundwater monitoring assessment
program are given in Figure 10. Notice that wells of various depths are sometimes
placed in "clusters" at a single location, thereby allowing for an assessment of the
groundwater at various depths.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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Groundwater Monitoring - 25
Figure 10
SAMPLE OF ASSESSMENT PHASE MONITORING WELL PLACEMENT
n
CONFINING LAYER
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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26 - Groundwater Monitoring
Recordkeeping and Reporting Requirements
Owners/operators of interim status TSDFs conducting ground water monitoring
must comply with the recordkeeping and reporting requirements of §265.94.
At a facility in the indicator evaluation phase (i.e., no release has occurred), the
owner/operator must keep all records of analyses required by §§265.92^), (d), and (e),
and §265.93(b). The owner/operator must also report the results of the following to
the RA (§§265.94(a)(2)(i)-(iii)).
What When
* Background concentrations in all Quarterly for first year
monitoring wells for parameters
under §265.92(b)(l)
• Concentrations of parameters Annually
under §265.92(b)(3)
• Groundwater surface evaluation Annually
under §265.93(f)
When a release has occurred and the uppermost aquifer is monitored pursuant to
§265.93(d)(4)/ the owner/operator must keep all records of analyses and evaluations
required under §265.93(d)(3) on-site and submit an annual report to the RA on the
status of the groundwater quality assessment program.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction to the topic used for Hotline training purposes.
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