United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5305W)
EPA530-K-02-010I
October 2001
&EPA
RCRA, Superfund & EPCRA
Call Center Training Module
Introduction to:
Groundwater Monitoring
(40 CFR Parts 264/265, Subpart F)
Updated October 2001
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DISCLAIMER
This document was developed by Booz Allen Hamilton Inc. under contract 68-W-01-020 to EPA.
It is intended to be used as a training tool for Call Center 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 Call Center training and
is not used as a reference tool on Call Center calls. The Call Center 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, Superfund & EPCRA Call Center 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 Call Center is open from 9 am to 5 pm Eastern Time,
Monday through Friday, except for federal holidays.
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GROUND WATER MONITORING
CONTENTS
1. Introduction 1
2. Regulatory Summary 2
2.1 Permitted Facility Groundwater Monitoring 6
2.2 Interim Status Groundwater Monitoring 18
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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 Part
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 Call Center training purposes.
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2 - Groundwater Monitoring
2. REGULATORY SUMMARY
The groundwater monitoring regulations in Part 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 and 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 Part 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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Groundwater Monitoring - 3
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 (X260.10). 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
(SDWA); 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 Call Center training purposes.
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4 - Groundwater Monitoring
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
ater 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 - 5
Figure 2
SCHEMATICS OF AN UPPERMOST AQUIFER
uppermost
aquifer
§
P
hydraulic 1
along fault line
'I;!;! 1 1 1;;^$^
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
1^1^
W
uppermost
aquifer
ater 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 Call Center training purposes.
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6 - Groundwater Monitoring
2.1 PERMITTED FACILITY GROUNDWATER MONITORING
EPA has the authority to require the owner and 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 and operators 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 (Z264.90(b)). These waivers or
exemptions apply to units for which any of the following apply:
¥ The unit is exempt from Part 264 under^64.1 (/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 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 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))
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
¥ The waste pile is designed and operated in accordance with/264.250(c) (Z264.90(b)(5)).
Owners/operators of regulated units must also conduct groundwater 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, or if the facility is conducting groundwater
monitoring during the compliance period (^264.90(c)(2) and (3)). 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
X264.97. 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 Call Center training purposes.
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8 - Groundwater Monitoring
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)
NO
YES
Clean Closure?
§264.90(c)
Key
LF - Landfill
LTU - Land Treatment Unit
SI - Surface Impoundment
WP - Waste Pile
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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Groundwater Monitoring - 9
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 and
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 and operator 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 Call Center training purposes.
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10 - Groundwater Monitoring
Figure 4
EXAMPLES OF GROUNDWATER MONITORING SYSTEMS FOR MULTIPLE
REGULATED UNITS
t
Hazardous Waste
Management Unit A
Hazardous Waste
Management Unit B
' © - © -©-
L _ @. _0_ .0 _ J
V
Hazardous Waste
Management Unit A
©
©
'- © - © -©- -©
-I
Hazardous Waste
Management Unit B
0
----- _0__0_0_0
KEY
Limit of Waste Management Area
Upgradient Well
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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Groundwater Monitoring - 11
STATISTICAL ANALYSIS
The owner/operator 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). 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)
(/264.98(b)). The owner and operator 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 Call Center training purposes.
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12- Groundwater Monitoring
Using the statistical methods in/264. 97(h), the owner and operator 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 and operator 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 and operator must:
¥ Notify the RA within 7 days indicating which parameter(s) or constituent(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
If the owner and 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 and operator will be released from the
requirements to conduct compliance monitoring or to submit a permit modification. The owner
and 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 and operator 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 and operator 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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Groundwater Monitoring - 13
Figure 5
SUMMARY: DETECTION MONITORING PROGRAM (X264.98)
as monitoring revealed
contamination?
O
ompliance Monitoring
ES
264.91 (a) (4)
270.14(c)(6)(l)
elected levels >
WPS?
stablish background values for parameters or
onstituents specified by the RA in the permit
o be used in Detection Monitoring
264.97(g)
O
ES
0
mplement 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)
ES
264.98(g)(6)
rigger SSI?
O
ES
264.98(f)
M
A
W
WPS =
u
SI
Demonstrate SSI not from RU
O
T
mpliance Monitoring
Detected levels >
GWPS?
ES
N
0
*J
0
Groundwater
Groundwater Protection Standards
Regulated Unit
Statistically Significant Increase
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 Call Center training purposes.
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14 - Groundwater Monitoring
Groundwater Protection Standard
The GWPS is used to indicate when corrective action is necessary to control plumes of
contamination from regulated units (X264.92). 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 (Z264.93)
¥ The concentration limits for each of the hazardous constituents (X264.94)
¥ The point of compliance (7264.95)
¥ The compliance period during which the GWPS applies (X264.96).
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 (7264.96) and the point at which
the GWPS applies, known as the point of compliance (7264.95). The point of compliance is the
vertical surface at which the owner and 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 the owner and operator 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 and
operator must determine whether the regulated units are in compliance with the GWPS at the
point of compliance during the compliance period.
The owner and 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 and operator must collect a minimum of four
samples from the background and compliance wells at least semiannually during the compliance
period. The RA will specify the frequency for collecting samples and the statistical method
appropriate to determine if an SSI has
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
Figure 6
SCHEMATIC OF POINT OF COMPLIANCE
LIMIT OF THE WASTE MANAGEMENT AREA
TWO-DIMENSIONAL POINT OF COMPLIANCE |-
UPPERMOST AQUIFER
Direction of Groundwater Flow
occurred. The uppermost aquifer flow rate and direction must also be determined at least
annually (/264.99(d)-(f)).
The owner and operator must analyze samples from compliance wells for all Part 264, 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 and operator must notify the RA in writing within seven
days. The owner and operator must indicate which concentration limits have 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 Call Center training purposes.
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16 - Groundwater Monitoring
submit a permit modification within 180 days to establish a corrective action program, and
continue to monitor in accordance with the compliance monitoring program (/264.99(h)).
If the owner and 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 and 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 and operator must initiate corrective action. Figure 7 presents an overview of the
compliance monitoring program.
STAGE IH: 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 and operator either
remove the hazardous constituents or treat them in place (/264.100(b)). The RA determines the
time period by which the owner and operator must begin corrective action after the GWPS is
exceeded (/264.100(c)). 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. The owner and operator 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 and 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
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
Figure 7
COMPLIANCE MONITORING PROGRAM SUMMARY (X264.99)
• 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
Establish GWPS (§264.92)
.List of HC
. Concentration Limits of HC
. Point of Compliance
. Compliance Period
§264.99(a)
• Implement Compliance Monitoring Program
1. Semiannual monitoring
2. Flow rate and direction annually
3. Appendix IX analysis annually
Exceed GWPS?
YES I §264.99(h)
Demonstrate the release
is NOT from a Regulated
Unit?
O
YES
§§264.99(e)-(g)
§264.99(1)
ey
A - Corrective Action
WPS - Groundwater Protection Standards
C - 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 Call Center training purposes.
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18 - Groundwater Monitoring
to the extent necessary to achieve compliance with the GWPS. Once compliance with the GWPS
has been achieved, the owner and 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 action must continue as long as necessary to achieve the GWPS. The
owner and 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 and operator may then reinstate a detection monitoring program.
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 the
owner and operator 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 and 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 (X265.90(c)). Owners and 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 and operator must demonstrate that there
is no potential for migration of hazardous wastes from the impoundment (Z265.90(e)).
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
Figure 8
OVERVIEW OF THE CORRECTIVE ACTION PROGRAM (264.100)
Notify RA
Submit Permit Modification and
Corrective Action Plan
mplement CA
. Bring RU into compliance
. Prevent HC from exceeding GWPS
. Remove or treat HC in place
264.99(h)
ompliance Monitoring
orrective Action
§264.100(a)and(b)
ES
stablish and implement
rogram to demonstrate
ffectiveness of CA program
T
eport effectiveness to RA
emiannually
T
chieve GWPS?
CA - Corrective Action
CM - Compliance Monitoring
GWPS - Groundwater Protection Standards
HC - Hazardous Constituents
RA - Regional Administrator
RU - Regulated Units
T
0
264.99(d)
264.99(g)
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 Call Center training purposes.
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20 - Groundwater Monitoring
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. 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 and
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 and 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)).
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
Figure 9
APPLICABILITY OF GROUNDWATER MONITORING FOR INTERIM STATUS
FACILITIES
Part 265, Subpart F
Not Required
NO
Interim status surface
impoundment,
landfill, or land
treatment unit?
YES
§265.90(a)
YES
Low Migration
Waiver?
Alternative
groundwater
monitoring program
(Assessment)
YES
§265.90(c)
NO
Statistically significant
increase (SSI) of
indicator parameters
assumed?
§265.93(d)
YES
§265.90(d)
NO
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 Call Center training purposes.
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22 - Groundwater Monitoring
Owners and 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 Parameters quarterly annually
(Chloride, Iron, Manganese, Phenols, Sodium,
Sulfate)
Groundwater Contamination quarterly semi-annually
Indicator Parameters
(pH, Specific Conductance, 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.
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 and 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
significant 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 and operators 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 and operator make this
determination, they have to establish the rate, extent of migration, and the concentrations 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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Groundwater Monitoring - 23
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 and 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 and operator may reinstate the basic indicator evaluation
program. If the analyses performed on the second round of samples confirms an SSI, the owner
and 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 and operator and submitted to the RA. The assessment plan must include the number
of 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 and 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, the owner and 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 Call Center training purposes.
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24 - Groundwater Monitoring
Figure 10
SAMPLE OF ASSESSMENT PHASE MONITORING WELL PLACEMENT
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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Groundwater Monitoring - 25
Recordkeeping and Reporting Requirements
Owners and operators of interim status TSDFs conducting groundwater 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 and
operator must keep all records of analyses required by/265.92(c), (d), and (e), and/265. 93 (b).
The owner and operator must also report the results of the following to the RA (/265.94(a)(2)).
What When
¥ Background concentrations in all Quarterly for first year
monitoring wells for parameters under
/265.92(b)(l)
¥ Concentrations of parameters under Annually
¥ Groundwater surface evaluation under Annually
/265.93(f)
When a release has occurred and the uppermost aquifer is monitored pursuant to/265.93(d)(4),
the owner and 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 Call Center training purposes.
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