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OVERVIEW
The publication consists of two guidance documents designed to be
used in tandem: The RCRA Ground-Water Monitoring Compliance Order
Guidance and the Draft RCRA Ground-Water Monitoring Technical Enforcement
Guidance Document. Together these two documents provide comprehensive
guidance on how to identify and rectify ground-water monitoring violations
at RCRA hazardous waste facilities. Both documents should be read by all
individuals involved in addressing RCRA ground-water monitoring problems
including regional and state enforcement officials, permit writers, field
inspectors, and attorneys.
The Draft RCRA Ground-Water Monitoring Technical Enforcement
Guidance Document (TEGD), provides draft guidance on how to evaluate the
technical adequacy of a facility's interim status monitoring system. The
document discusses each of the elements that is important to the overall
adequacy of an owner/operator's monitoring system and, where possible,
makes specific judgements on what activities and methodologies are
appropriate to meet the terms of the regulations. Specifically, the TEGD
provides guidance on how to evaluate:
• the owner/operator's hydrogeologic characterization of the
facility;
• the adequacy of the number and location of ground-water
monitoring wells;
• the design and construction of the monitoring wells;
• the sampling and analysis plan;
• the statistical analysis of the monitoring data; and
• the owner/operator's assessment plan.
U.S. EnvijiQRiMntal Protection Agency
Regi.n 5, L^r^y (5PL-16)
230 S. Dearty^ fit -eet, Room 1670
Chicago, H '
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Enforcement officials should consider the guidance in the TEGD to help
determine whether an existing monitoring system is in compliance with
the regulations. In addition, enforcement officials should consider the
recommendations contained in the TEGD when directing respondents to
undertake ground-water activities pursuant to an enforcement order.
The RCRA Ground-Water Monitoring Compliance Order Guidance, (COG)
presents the Agency's strategy for correction of ground-water problems at
interim status land disposal facilities. The cornerstone of this
strategy is the issuance of orders that correct existing interim status
ground-water violations in a manner consistent with the needs of the RCRA
permitting program. The guidance encourages the development of technical
ground-water remedies that integrate the facility's interim status
monitoring obligations (Part 265) with the requirements mandated by the
permit application regulations (Part 210). By integrating the two sets
of regulations, the Agency hopes to speed the issuance of operating and
post-closure permits, thereby bringing the regulated community under the
stricter requirements of Part 264 as quickly as possible.
HOW TO USB THIS MANUAL
The Compliance Order Guidance and the Draft Technical Enforcement
Guidance Document have been bound together in order to emphasize that the
documents should be used jointly. The COG should be read first because
this document introduces the Agency's approach to ground-water compliance
and provides important background information on the interrelationship of
the Part 265, Part 270, and Part 264 ground-water regulations. Even
individuals more interested in the technical aspects of a facility's
ground-water monitoring program will benefit from the regulatory back-
ground and policy context provided by this document. Next, regional and
state personnel should read the TEGD. The TEGD provides draft technical
information to evaluate existing systems and develop the type of highly
specific orders encouraged by the COG. As with the COG, even those
C
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individuals not directly involved in the technical aspects of ground-
water monitoring will benefit from familiarity with the criteria and
information that technical staff use to design and evaluate ground-water
programs.
COORDINATION IN THE ENFORCEMENT PROCESS
The implementation of this guidance will require the coordinated
effort of many actors with different technical, policy, and legal exper-
tise. Technical enforcement staff (e.g., hydrogeologists, statisticians),
permit writers, field inspectors, and enforcement attorneys will all have
to work together to achieve the comprehensive remedies and detailed orders
envisioned by the COG. The TEGD and the COG were designed to facilitate
and inform this group effort.
The coordination between actors begins before the field inspector
conducts the site visit. Prior to the site visit, the technical
enforcement staff member should gather and review all information
available about the facility including, among other documents, the
facility's Part A and Part B permit applications, previous inspection
reports, and existing facility records. Next, the enforcement staff
person and the field inspector should meet to develop a plan of action
for the inspection. Having performed an initial evaluation of the
facility, the technical staff person should be able to provide guidance
to the field inspector on what further information to collect and what
potential problems should be investigated during the site visit.
(Further guidance on how to prepare and conduct field inspections is
forthcoming in the Agency's upcoming Field Inspection Guide to be issued
in draft in September). Pre-inspection planning and analysis should
culminate in a written inspection plan developed jointly by the technical
staff and the field inspector.
After the site inspection, coordination continues when the inspec-
tor and the technical staff meet to discuss the findings of the field
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inspection. The outcome of this meeting should be a decision as to
whether compliance problems may exist and what additional information,
if any, is necessary to confirm the nature and extent of any potential
violations. Often at this point, a follow-up inspection is appropriate
to verify whether or not compliance problems exist at the facility and to
gather any additional information necessary to support an enforcement
action. Generally this more in-depth inspection will be performed by a
technical person, most likely an engineer or hydrogeologist, who has the
expertise to independently evaluate elements of the facility's ground-
water monitoring program. Once back in the office, this person will be
able to consider guidance in the draft TEGD and his/her own professional
judgment to decide whether the owner/operator's monitoring program is
technically adequate.
If the review indicates that the facility's monitoring program is
not in compliance with Part 265, the technical enforcement staff and the
permit writer should meet to conceptualize a technical remedy for
incorporation in an order. Coordination between enforcement and
permitting is essential at this point to ensure that any enforcement
action taken is consistent with the long term monitoring obligations of
the facility. As the COG points out, most facilities will have ground-
water obligations imposed by Part 2"70 and Part 264 over and above those
required by Part 265. A technical remedy designed to address Part 265
violations should anticipate and be consistent with the facility's future
monitoring obligations pursuant to Part 264. Likewise, if the facility's
operating or post-closure permit is due, the remedy in the order should
require the respondent to generate any ground-water data, information, or
plans required to meet the facility's permit application responsibilities
pursuant to Part 270.
Once the permit writer and enforcement official decide what activi-
ties should be compelled, the enforcement staff and regional counsel must
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develop an enforcement strategy to secure the desired remedy. Central to
the strategy is the selection of which order authority and (where appro-
priate) what regulatory citations should be used to compel the required
activities. The COG provides useful background information on the various
order authorities and compares them with respect to the conditions for
order issuance, the types of actions they may compel, and applicable
appeal procedures, if any. In addition, the COG provides guidance on how
to select among order authorities and how to relate specific technical
inadequacies back to the regulatory language.
As a final step in the enforcement process, enforcement officials
and regional counsel must develop an order to compel the desired
activities. Here both documents will come into play. Enforcement
officials can consider technical information provided in the draft TEGD
to decide which methodologies, design configurations, and construction
materials should be mandated by the order. Then enforcement staff and
counsel can use the COG for suggestions on how to write ground-water
orders that are easily enforced and effective at achieving the desired
remedy. Together the TEGD and COG will help reduce the opportunity for
wasted effort, misunderstanding, and delay by ensuring that future
ground-water orders are explicit about which techniques and approaches
will be considered appropriate or adequate.
Figure One illustrates the various steps in the enforcement process
and highlights the level of coordination necessary to fully implement the
guidance presented in this manual. While the actors and steps needed to
remedy any particular ground-water problem will vary, the flow chart
illustrates the highly complex task of bringing a RCRA facility back into
compliance with the ground-water regulations. The Agency hopes that this
manual will facilitate this task.
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ACTIVITIES
PERSONS INVOLVED
PREINSPECTION ANALYSIS
AND PLANNING
i
i
FIELD INSPECTION
REVIEW OF FIELD
INSPECTION REPORT
FOLLOW - UP
\
INSPECTION
i
TECHNICAL EVALUATION
OF FACILITY
INFORMATION - APPLICATION
OF TEGD
1
r
CONCEPTUALIZATION OF
TECHNICAL REMEDY
1
r
DEVELOPMENT OF
ENFORCEMENT CASE STRATEGY
FIELD INSPECTOR
TECHNICAL ENFORCEMENT
STAFF
• FIELD INSPECTOR
• FIELD INSPECTOR
• TECHNICAL ENFORCEMENT
STAFF
• TECHNICAL ENFORCEMENT
STAFF
• TECHNICAL ENFORCEMENT
STAFF
• TECHNICAL ENFORCEMENT
STAFF
• PERMIT WRITER
• TECHNICAL ENFORCEMENT
STAFF
• REGIONAL COUNSEL
DEVELOPMENT OF
COMPLIANCE ORDER
• TECHNICAL ENFORCEMENT
STAFF
• REGIONAL COUNSEL
FIGURE 1. OVERVIEW OF THE ENFORCEMENT PROCESS
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RCRA Ground-Water Monitoring
Compliance Order Guidance
Final
August 1985
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TABLE OF CONTENTS
Page
1. INTRODUCTION
1.1 Purpose and Objectives 1-1
1.2 Significance of the Interim Status to Permitting Transition 1-2
1.2.1 Plume Characterization Under §270.14(c)(4) 1-4
1.3 Overview of the Enforcement Process 1-6
1.3.1 Case Initiation 1-8
1.3.2 Facility Management Planning 1-11
1.4 Relationship to "Late and Incomplete Part B Policy" 1-13
1.5 Structure of this Document 1-14
2. REGULATORY OVERVIEW
2.1 Interim Status Ground-Water Monitoring - Part 265 2-1
2.1.1 Detection Monitoring 2-2
2.1.2 Assessment Monitoring 2-5
2.2 Permit Regulations for Ground-Water Monitoring - Part 264
2.2.1 Detection Monitoring 2-8
2.2.2 Compliance Monitoring 2-9
2.2.3 Corrective Action 2-12
2.3 Permit Application Regulations - Part 270
2.3.1 Information Requirements of §270.14(c) 2-14
2.3.2 Information Requirements for Appropriate 2-16
Part 264 Ground-Water System
3. REGULATORY COMPARISONS
3.1 Part 265 vs. Part 264 Detection Monitoring
3.1.1 Well Placement 3-2
3.1.2 Indicator Parameters 3-5
3.1.3 Sampling Frequency 3-5
3.1.4 Appropriate Sampling Techniques 3-5
3.1.5 Statistical Comparisons 3-7
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TABLE OF CONTENTS (con't.)
3.2 Part 264 Detection Monitoring vs. Part 264 Compliance Monitoring
3.2.1 Well Placement and Network Design 3-8
3.2.2 Establishing Background Concentrations 3-10
3.2.3 Sampling Frequency 3-11
3.2.4 Statistical Comparisons 3-11
3.3 Part 265 Assessment Monitoring vs.
§270.14(c)(4) Plume Characterization 3-12
4. OVERVIEW OF ORDER AUTHORITIES
4.1 Comparison of §3008(a), §3008(h), and §3013 Orders
4.1.1 Actions the Orders May Require 4-2
4.1.2 Conditions for Order Issuance 4-5
4.1.3 Formal Administrative Proceedings 4-17
4.2 Selection Among Order Authorities 4-18
5. FASHIONING A REMEDY AND DEVELOPING THE ENFORCEMENT STRATEGY
5.1 Types of Violators 5-1
5.2 Profile of a "Transition-Period" Violator 5-3
5.3 Outline of the Remedy 5-4
5.4 Discussion of the Remedy 5-9
5.4.1 Design and Installation of the Monitoring Network 5-9
5.4.2 Confirmation of Leakage Based on Expanded Sampling 5-11
5.4.3 Fulfillment of Applicable Part 270 Requirements 5-13
5.5 Application of Enforcement Authorities to the Remedy 5-15
5.5.1 Selection of the Order Authority 5-16
5.5.2 Securing the Model Remedy Through a §3008(a) Order 5-18
5.6 Variations on the Model Scenario 5-20
6. DEVELOPING ORDERS
6.1 Importance of Specificity 6-1
6.2 Phased Orders for Ground-Water Monitoring Violations 6-3
ii
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TABLE OF CONTENTS (continued)
page
6.3 Technically Specific Orders 6-6
6.4 §3008(a) Orders 6-13
6.5 §3013 Orders 6-16
6.6 §3008(h) Orders 6-17
TABLE OF FIGURES
1.1 Model of the Enforcement Process 1-7
3.1 Relationship of the Waste Management Area to 3-4
the Point of Compliance
3.2 Well Placement in Compliance Monitoring 3-9
4.1 Comparison of Order Authorities 4-3
4.2 Ground-Water Performance Standards 4-8
4.3 Relationship of Technical Inadequacies to Ground-Water
Performance Standards 4-9
5.1 Violator-Classification Scheme 5-2
5.2 Ground-Water Monitoring Sequence as Originally Envisioned 5-6
5.3 New Ground-Water Compliance Strategy Based on Condensed
Monitoring Sequence 5-10
5.4 Model Remedy with Regulatory Citations 5-18
5.5 Variations on Model Remedy and Enforcement Response 5-24
6.1 Possible Elements of a Technically-Specific Order 6-8
LIST OF APPENDICES
Appendix A: Model Phased Order A-l
Appendix B: Diagram of Administrative Proceedings B-l
iii
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CHAPTER 1
INTRODUCTION
1.1 Purpose and Objectives
The purpose of this document is to guide enforcement officials in develop-
ing administrative orders to address RCRA ground-water monitoring violations at
interim status land disposal facilities.1 The document's primary objective is
to promote the development of orders that correct interim status violations
in a manner that is consistent with the needs of the RCRA permitting process.
Enforcement personnel are encouraged to involve permit writers in the formu-
lation of technical remedies to ensure that enforcement remedies are consistent
with the long-term monitoring responsibilities of the facility.
The guidance is intended to apply to the RCRA-authorized States as well
as to EPA regional offices. While State and Federal enforcement authorities
may differ (e.g., states may have different order authorities or different
maximum penalties), the States and EPA are enforcing essentially the same
set of regulations. Therefore, remedies designed by State enforcement
officials should be similar to those outlined in this document.
The document will not be concerned with policy matters such as how to
decide which cases to pursue or how to decide between administrative and
1 This document covers only the requirements for ground-water monitoring
that apply to hazardous waste management units that were in existence on November
19, 1980. It does not address monitoring requirements that may be imposed on
solid waste management units as a result of the "continuing releases" provision,
§3004(u) of RCRA, as amended by the Solid and Hazardous Waste Act Amendments
of 1984.
1-1
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judicial response. Instead, the document focuses on the formulation of
technical remedies and on the appropriate technical content of orders.
Specifically, it concentrates on how to fashion ground-water remedies for
facilities operating during the transition period between interim status
and permitting.
1.2 Significance of the Interim Status to Permitting Transition Period
The Agency and the regulated community are now entering a period unique
in the life of the RCRA program — the period after which all Part B permit
applications are due, but before all facilities have been permitted. EPA
and the States have already received many Part B applications. By November
8, 1985 the Part B permit applications of all the nation's land disposal
facilities will be due.2 it is likely, however, that it may take several
years for EPA to process and finalize permits for all these facilities. As
a result, many facilities will face a fairly long period of time between the
due date of their application and the issuance or denial of a permit.
The existence of this transition period is significant because it is
the only time in the life of the RCRA program that land disposal facilities
will be bound by the interim status ground-water regulations (Part 265) and
the permit application regulations (Part 270). It is the first time, therefore,
2 The Solid and Hazardous Waste Act Amendments of 1984 require all
land disposal facilities to submit a Part B permit application within twelve
months after the enactment of the Amendments or lose interim status. See
§3005(e) of the Resource Conservation and Recovery Act (RCRA).
1-2
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that enforcement officials can draw upon the authorities of both Part 265
and 270 when fashioning technical remedies at interim status facilities.
As described in Chapter 3, the Part 270 regulations impose additional
monitoring and information generating requirements on the owner/operators
of interim status facilities. The Agency designed the interim status
(Part 265), permit application (Part 270), and permitting regulations
(Part 264) to be followed in sequence. A facility moves from one phase of
monitoring to the next (and from interim to permitted status) by building
upon the information generated during the previous stage. The monitoring
and cleanup obligations of an owner/operator also expand as the facility
approaches permitting and/or the evidence of ground-water contamination
increases.
Unfortunately, certain facilities have not adequately implemented even
the first phase of the monitoring sequence, the installation of a competent
detection monitoring network. Consequently, these owner/operators cannot
provide the sampling data or plume characterization required for a Part B
permit application.
Enforcement officials can help solve this problem by crafting technical
remedies that integrate the requirements of Parts 265 and 270. Facilities
that have failed to progress through the monitoring sequence as planned,
should be required to condense the sequence so as to prepare the facility
for permitting as rapidly as possible. Much of this document concentrates
on exploring how enforcement officials can use the requirements of Parts
1-3
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265 and 270, and other available authorities to design remedies that will
ease the transition between interim and permitted status.
1.2.1 Plume Characterization Under §270.14(c)(4)
In terms of ground-water monitoring, the most significant requirement
of the Part 270 regulations is the provision outlined in §270.14(c)(4).
This provision requires applicants to describe any plume of contamination
that has entered ground water and define its extent, and provides EPA with
the authority to compel sampling for the broad list of constituents listed
in Appendix VIII of Part 261 (hereafter referred to as "Appendix VIII").
This provision applies to all facilities that have detected plumes
under interim status monitoring and to facilities that have not detected
plumes if the facility's interim status system is not capable of detecting
a plume should it occur.•* Facilities with inadequate 265 monitoring
systems should not be allowed to avoid Appendix VIII sampling and assessment
activities simply because they have avoided compliance with RCRA ground-water
monitoring requirements in the past. Moreover, such facilities should not
be allowed to delay undertaking the more comprehensive assessment and
sampling activities mandated by §270.14(c)(4), by first going back and
-* This interpretation has been consistently advanced in all previous
guidance documents that address this issue. (See: the RCRA Permit Writer's
Guidance Manual For Ground-water Protection, October 1983, p. 204; and the
November 29, 1984 policy memorandum from Lee Thomas and Courtney Price,
entitled, "Part B Applications with Incomplete Ground-water Monitoring
Data.") Moreover, this expectation has been made known to facility owners
through the Permit Applicant's Guidance Manual, May 1984 (See pps. 9-42
and 9-43).
1-4
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implementing the less demanding monitoring protocol established in Part
265. Requiring these facilities to sample for Appendix VIII constituents
is consistent with the language of §270.14(c)(4) and the general purposes
of the Part 265 requirements.
One of the purposes of the Part 265 regulations was to prepare facili-
ties for permitting. EPA assumed that data from detection and assessment
monitoring under Part 265 would identify facilities that had contaminated
ground water. These data would serve as the foundation for developing the
ground-water information required to be submitted in Part B of the permit
application [§270.I4(c)]. Where an owner/operator has not complied with
Part 265 monitoring requirements, however, EPA cannot determine whether
the facility has contaminated ground water and hence cannot easily determine
which ground-water monitoring program should be written into the facility's
permit.
At this point in the program, allowing an applicant to comply with
the literal requirements of Part 265, however, would cause unacceptable
delays. An applicant that needed to "start-over" by installing or relocat-
ing monitoring wells could require as much as two and one-half years to
complete the entire Part 265/Part 270 monitoring sequence (see timeline in
Figure 5.2). Consequently, where EPA finds that an applicant has not
instituted an adequate monitoring program under Part 265, the Agency will
require owner/operators to condense the Part 265/Part 270 monitoring sequence
in order to generate the ground-water data necessary for permitting (closure
or post-closure) as quickly as possible. This condensed monitoring program
is described in more detail in Chapter 5.
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1.3 Overview of the Administrative Enforcement Process
The unique character of the transition period from interim status to
permitting demands both increased coordination between permit writers and
enforcement staff and a new conceptual approach to the enforcement process.
The cornerstone of this new approach is the fashioning of technical ground-
water remedies that satisfy the Agency's long terra regulatory objectives.
To implement this approach, the Agency recommends a three-step enforce-
ment process (see Figure 1.1). STEP 1 is to outline the technical remedy
sought. In most cases, this step will require considerable planning and
close coordination between the enforcement staff and the permitting staff.
Enforcement officials and permit writers must work together to construct
remedies that generate the information necessary for permitting while
correcting deficiencies in the facility's interim status monitoring system.
STEP 2 is to develop an enforcement strategy to secure the desired
remedy. Central to this effort is the selection of the order authority
best suited to compel the remedy. If regulatory provisions have been
violated, the enforcement staff should determine whether the desired remedy
can be secured through a §3008(a) order citing these violations. (See Chapter
4 for a description of the order authorities and a discussion of their use.)
If there is a question whether the entire remedy can be compelled using a
§3008(a) order, enforcement staff should consider using a different
enforcement authority (e.g., §3008(h), §3013, §7003 or CERCLA §106 orders),
or a combination of authorities if necessary.
1-6
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STEP 3 of the administrative enforcement process is the development
of the order. The order is the mechanism by which the Agency ensures that
the desired remedy is actually executed by the facility. The goal of this
step is to formalize exactly what actions the respondent must take in
order to come into compliance. The more explicitly the Agency can express
its expectations, the less opportunity there is for misunderstanding,
wasted effort, and delay. As Chapter 6 explains, it is important to develop
this specificity as early in the enforcement process as possible, although
unless default is expected, it may not be necessary to express it in the
compliance order accompanying the complaint. Chapter 6 provides guidance
on how to write orders that are easily enforced and effective at achieving
the remedy developed in STEP 1.
1.3.1 Case Initiation
Targeting cases for this enforcement process is the responsibility of
both the enforcement staff and the permits staff.
In the enforcement program, cases generally evolve from the discovery of
an inadequate interim status monitoring program. Inadequate systems may be
identified as a result of routine facility inspections, more detailed ground-
water inspections, or enforcement file reviews. Once a problem-facility
is identified, enforcement staff should immediately contact the permits
staff to determine the facility's status vis a vis the permitting program.
Early coordination with the permits staff is important for two reasons.
First, the permits staff may have information on the site that could aid
1-8
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in the development of an enforcement action against the facility. Where
complete, for example, a Part B application can provide valuable informa-
tion regarding a facility's wastes, the hydrogeology of a site, etc. Even
where deficient, a Part B application can prove useful to enforcement officials
by highlighting gaps in the facility owner's understanding of his/her site.
Second, coordination is necessary to avoid duplication of effort and to
ensure that actions taken by the enforcement division are "consistent with"
and "supportive of" the permitting process. Consistency is important so
that the Agency presents a unified front to the facility. For example,
before issuing a complaint the enforcement staff should know whether there
is an outstanding Notice of Deficiency (NOD) compelling the same activities.
"Supportive of permitting" implies consideration of the permit writer's
informational needs when designing remedies. The permit writer must become
involved in the enforcement process early on so that (s)he can ensure that
his/her own permit-writing needs and the facility's future Part 264 monitoring
needs are accurately represented and accounted for during the development
of the remedy.
Cases may also enter the enforcement process via the permits staff. In
fact, permit wnriters (by virtue of their Part B reviews) are often in the best
position to identify problem cases. Permit writers are encouraged to refer
cases to enforcement and use enforcement staff to facilitate the permit
process.
Enforcement involvement may be appropriate, for example, when a facility
has submitted a highly deficient Part B and past dealings with the company have
1-9
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demonstrated that the owner/operator is unlikely to correct deficiencies in
a prompt and forthright manner. In such cases, the permit writer should
consider referring the case to enforcement immediately after issuing a
general NOD that requires the submittal of the missing information within
a very short period of time. Historically recalcitrant applicants should
not be given long periods of time under the informal NOD process to generate
data/information that they should have developed by the due date of their
permit; rather they should be compelled to develop this information on an
enforceable compliance schedule pursuant to an order. Likewise, if a permit
writer has failed to make progress using the NOD mechanism, (s)he should
work with the enforcement division to use formal mechanisms to compel
compliance rather than continue to issue NODs.
Permit writers should also expand their initial "completeness" review
of incoming Part Bs to include an abbreviated technical assessment of the
ground-water monitoring portion of the application. While the permitting
staff clearly does not have the resources to consider all Part B applications
in full as they arrive, there are benefits in focusing briefly on the parts
of each application that are particularly troublesome for the regulated
community, are environmentally sensitive, or will require a long time for
the facility to revise if the application is inadequate. Some aspects of
an application are so central to the adequacy of the permit in general
that it may be wise to perform an abbreviated assessment up front, rather
than wait until the entire permit can be reviewed to discover and correct
major deficiencies (e.g., the facility must install an entirely new well
system before it can generate the data necessary for permitting).
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The consequences of not identifying such deficiencies up front could
be significant delays in the permitting process or a weakening of future
enforcement cases because so much time has elapsed between the submittal of
the application and the issuance of a complaint. If permit writers did
conduct abbreviated reviews on the ground-water portion of incoming applica-
tions, they could refer cases with major deficiencies to the enforcement
staff. Enforcement officials could then use the combined authorities of
Parts 265 and 270 (or other authorities as necessary) to advance the facility
to the point where the ground-water monitoring portion of the permit could
be easily written when the facility's full application comes up for review.
1.3.2 Facility Management Planning
The enforcement process as described above demands a high level of
coordination between the enforcement and permitting staffs. For any parti-
cular facility, the Agency and States must decide whether ground-water
problems should be addressed through enforcement or through the permitting
process. Facility Management Planning (FMP) is the mechanism that Regions
and States should use to orchestrate this division of labor.
As described in the Revised FY85 and FY86 RCRA Implementation Plans
(RIP), the draft National Permit Strategy (April 8, 1985), and the draft FMP
guidance (July 12, 1985), Facility Management Planning is an Agency tool
for coordinating effort and resources between the Regions/States and
enforcement/permitting. Regions must develop a Facility Management Plan
for all "environmentally significant" facilities according to a schedule
laid out in the RIP. Each plan must identify: 1) what action(s) should
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be taken at (or by) a facility; 2) what tool (e.g., order, NOD, post-closure
permit) should be used to compel the action; and 3) who (State or Region,
enforcement or permitting) has lead responsibility for ensuring that the
action is completed.
Decisions regarding the above points evolve from a "facility analysis"
conducted by representatives from Regional and State permitting and enforce-
ment offices. During the facility analysis, the various representatives
review the information available on a facility (e.g., Part B, inspection
reports, etc.) and begin formulating a strategy for handling that facility
in the short and long term. All strategies devised for individual facilities
must be in accord with the RIP and other Agency policies.
Where actual or potential ground-water contamination exists, the
strategy will generally include data or information gathering to support
the long-term goal of either issuing the facility an operating permit or
closing the facility and implementing corrective action for releases
into ground water.
It is during the facility management planning process that enforcement
officials and permit writers can initiate the type of coordination necessary
to implement a range of options including this guidance. The review group,
for example, may decide that eventually a facility should be issued a
permit, but in the interim the Agency should use an order to compel the
facility to investigate possible ground-water contamination and develop
the appropriate permit application data and plans. At this point, the
lead enforcement official should solicit the assistance of the permit
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writer in formulating the technical remedy necessary to advance the facility
toward permitting.
1.4 Relationship to "Late and Incomplete Part B Policy"
On September 9, 1983, Lee Thomas and Courtney Price issued a memorandum
entitled, "Guidance on Developing Compliance Orders Under Section 3008 of
the Resource Conservation and Recovery Act; Failure to Submit and Submittal
of Incomplete Part B Permit Applications." This memo, commonly referred to
as the "Late and Incomplete Part B Policy," affirmed the Agency's authority
to take enforcement action for late and incomplete permit applications. It
set out the procedures for addressing Part B violators and established a
flat penalty amount that should be assessed in each case.
The Late and Incomplete Part B policy has been largely superseded by
more recent policies and is further modified by this document. First, the
"Enforcement Response Policy" (December 21, 1984) established that Submittal
of a late, incomplete or inadequate Part B is a Class I violation (see page
18). In addressing Class I violations the Enforcement Response Policy states
that EPA and the States may issue warning letters prior to §3008(a) complaints
if they wish but are not required to do so. Therefore, the directive in the
Late and Incomplete Part B Policy that warning letters should always precede
§3008(a) complaints is superseded.
Second, the Late and Incomplete Part B Policy established a flat
penalty amount of $5,000.00. That requirement has since been superseded by
the "RCRA Civil Penalty Policy" (May 8, 1984), which establishes a matrix
that should be used to determine administrative penalty amounts. The matriK
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is based on two factors, the degree of a handler's deviation from regulatory
requirements and the potential for harm presented by the violation. Thus,
penalty amounts should be determined individually for each Part B violator;
the flat $5000.00 amount should not be applied automatically.
Finally, the Late and Incomplete Part B Policy envisioned issuing complaints
that require, simply, the submittal of missing information. The Agency has
since realized, however, that incomplete Part B's seldom represent mere over-
sights on the part of the applicant. More often, Part B's are incomplete
or inadequate because the applicant failed to generate the required informa-
tion and/or failed to comply with interim status requirements.
When issuing a complaint against a Part B violater, the Region or State
should not merely require the respondent to "submit the information required
in Section 'XYZ' of the regulations." Rather enforcement officials should
determine the underlying reasons for the poor Part B and detail in the
proposed order what needs to be done to ensure a proper submittal. Often
the reasons behind an inadequate Part B are extremely complex, especially
when the deficiencies involve ground-water monitoring. Enforcement officials
can help ensure the adequacy of the next submittal by outlining in the
order the nature and scope of the work to be performed. Further, Regions
and States should generally assess penalties for all Part 270 violations
and any contributing Part 265 violations.
1.5 Structure of this Document
This document is divided into six chapters. Chapter 2 presents an in
depth discussion of the Part 265 and Part 264 ground-water monitoring regula-
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tions. Chapter 3 builds upon this framework and explores the interrelation-
ship between the two sets of regulations. These two chapters are designed
to give enforcement officials the regulatory perspective they will need to
design ground-water remedies that are consistent with and supportive of the
permitting process.
Chapter 4 provides an overview of the enforcement tools available to
secure desired remedies. It compares and contrasts the various order author-
ities and discusses some of the factors enforcement officials should consider
when designing enforcement strategies.
Chapter 5 discusses how to fashion a technical remedy. The chapter
uses a case-study approach to illustrate how enforcement officials can
construct remedies that correct present violations while advancing a facility
toward permitting. The chapter develops a model remedy for a typical "transi-
tion-period" facility and then describes how to use the combined authorities
of Parts 265 and 270 to secure that remedy.
Finally, Chapter 6 discusses how to write an order to secure the
desired remedy. The chapter emphasizes the importance of specificity in
order writing and explores various strategies that may be followed in
developing and issuing administrative orders. Appendix A includes a model
order that illustrate some of the principles developed in this chapter.
The Agency has also prepared a draft document entitled, RCRA Ground-
Water Monitoring Technical Enforcement Guidance (TEGD). This document
addresses specific technical elements of ground-water monitoring system
design. For example, it discusses the types of well construction methods
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that the Agency considers acceptable for yielding representative water
samples. The draft final version of the TEGD is dated August, 1985 and
is available from the Office of Waste Programs Enforcement (OWPE).
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CHAPTER 2
REGULATORY OVERVIEW
This chapter provides an overview of the Part 265 and Part 264 ground-water
monitoring regulations. Tt attempts to abstract from the regulatory language
and describe how the programs were intended to function in the real world.
Enforcement and permitting officials are strongly encouraged to read this
chapter even if they are familiar with the regulations.
The chapter discusses only the requirements that apply to hazardous waste
management units. In accordance with the Solid and Hazardous Waste Amendments
of 1984, permitted facilities may soon be required to monitor solid waste
management units as well as hazardous waste management units. However, the
specific requirements applicable to these units have not yet been established
and will not necessarily be identical to the current Subpart F program detailed
below.
2.1 Interim Status Ground-Water Monitoring - Part 265, Subpart F
The goal of the Part 265 regulations Is to ensure that owners and
; operators of interim status landfills, land treatment facilities, and surface
t
; impoundments evaluate the impact of their facility on the uppermost aquifer
i
underlying their site. To achieve this goal, the regulations establish a
two-stage ground-water program designed to detect and characterize the
migration of any wastes that escape from a facility.
The focus of both stages of the program is on evaluating the nature and
extent of leakage, not on the removal or treatment of contamination should it
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be detected. Removal and treatment of contamination deemed unacceptable
must be dealt with through the exercise of the Agency's enforcement author-
ities under §3008(h) or §7003 of RGRA, §106 of CERCLA, or through the RCRA
permitting process (See Chapter 4 on Order Authorities and Section 2.2.3
of this chapter).
2.1.1 Detection Monitoring
Detection monitoring, the first stage of interim status monitoring,
is required at interim status land disposal facilities unless the owner/
operator can demonstrate that there is a low potential for migration of
hazardous waste from his/her facility to water supply wells or to surface
water. The objective of detection monitoring is to determine whether a land
disposal facility has leaked hazardous waste into an underlying aquifer
in quantities sufficient to cause a significant change in ground-water
quality.
To accomplish this objective, the regulations direct the owner/operator
to install a monitoring network which includes wells located downgradient
from the facility at the limit of the waste management area and wells
located upgradient that are capable of providing samples representative of
ground water unaffected by the facility. Although the regulations recognize
that for a small site with the simplest hydrogeologic subsurface three
downgradient wells and one upgradient well might suffice, the number,
depth, and location of wells must ultimately be selected so that the network
meets the regulatory performance standard of immediately detecting any
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migration of statistically significant amounts of hazardous waste or hazard-
ous waste constituents into the uppermost aquifer [§265.91(a)].
To determine whether leakage has occurred, the owner/operator must
compare monitoring data collected downgradient from his/her facility to
background water quality data established over an initial period of one
year. The comparison is based on three sets of parameters designed to
characterize water unaffected by the facility and to predict possible
leakage of hazardous waste.
The first set of twenty parameters, listed in Part 265 Appendix III,
defines the general suitability of the aquifer as a drinking water supply.
These parameters were selected because they are recognized by the Safe
Drinking Water Act as important to overall drinking water suitability.
The second set of parameters (chloride, iron, manganese, phenols, sodium,
and sulfate) establish general ground-water quality and can be used to
characterize the suitability of ground water for a variety of non-drinking
uses. Information on these parameters is largely collected in anticipation
of future confirmation of leakage. Should detailed assessment of ground
water prove necessary, historical data on these major ion groups will
help owner/operators predict the mobility of hazardous waste under actual
site conditions.
The final set of parameters includes four measures selected as gross
indicators of whether contamination of ground water has occurred. These
four indicators - pH, specific conductance, total organic carbon (TOG), and
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total organic halogen (TOX) - were chosen because of their widespread use,
their well-established test procedures, and their general ability to reflect
changes in the organic and inorganic composition of ground water. Faced
with designing a monitoring program that would be responsive to a large
undefined set of chemical compounds at unspecified concentrations, the
Agency chose to rely on broad, surrogate measures that could predict whether
significant contamination had occurred.
The regulations require the owner/operator to sample and analyze for all
three sets of parameters quarterly for one year. Quarterly sampling is
required so that seasonal effects will be incorporated into the characteri-
zation of background water quality. At the end of the first year, the owner/
operator must establish background for each contamination indicator by
averaging the quarterly measurements obtained for that parameter from the
upgradient wells. These upgradient mean values are important because they
establish the initial background concentrations to which all subsequent
upgradient and downgradient concentrations will be compared.
After initial background is established, the owner/operator continues
sampling on a less frequent schedule. The ground-water quality parameters
(chloride, phenol, etc.) must be analyzed at least annually and the contam-
ination indicators (TOX, pH, etc.), at least semi-annually.
At this point, however, detection monitoring begins to focus more
specifically on the four contamination indicators. Each time a facility
samples for a contamination indicator, the owner/operator must compare the
values obtained from his/her upgradient and downgradient wells with the
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mean values obtained for that parameter during the first year of background
sampling. (Note that both upgradient data and downgradient data are compared
to first year mean data derived from upgradient wells). The regulations
specify that the facility owner should use a Student's t-test to the .01
level of significance when making comparisons [265.93(b)]»
If a Student's t-test for an upgradient well shows a significant increase
in the concentration or value of an indicator parameter (or any change in pH),
it may mean that sources other than the facility are affecting ground water.
Alternately, a change in upgradient water quality could be due to mounding of
contaminated ground water beneath the facility or a change in hydraulic
gradient such that originally upgradient wells are now downgradient relative
to the facility. (This condition would be reflected in changes in ground-
water elevation measurements over time.) Whatever the cause, a significant
change in upgradient water quality should be investigated and noted in the
company's annual report to the Agency [§265.94(a)(2)(ii)].
A Student's t-test for a downgradient well that shows an increase in an
indicator parameter (or any change in pH), signals potential ground-water
contamination and is the first indication that a facility may be leaking.
If a statistically significant change is detected, the facility moves into
the second phase of interim status monitoring, ground-water assessment.
2.1.2 Assessment Monitoring
Once a significant change in water quality triggers a facility into
assessment, the owner/operator must notify the Agency and submit a proposed
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program for determining whether hazardous wastes or their constituents have
entered ground water and if so, their concentration, rate, and extent of
migration [§265.93(d)(2)]. Because detection monitoring parameters are
non-specific, a statistically significant change in one parameter may not
necessarily represent migration of hazardous waste constituents into ground
water. For example, pH could change independent of contamination if recharge
patterns at the site shifted such that ground water infiltrated through
formations with significant buffering capacity. The first step in assess-
ment monitoring, therefore, is to determine whether hazardous waste
constituents have indeed migrated into ground water.
In many cases, the detection monitoring network already installed at
the site can be used for this purpose. Of course, use of the existing
system assumes that the network is capable of detecting low part per billion
levels of hazardous waste constituents (listed Appendix VII of Part 261
and in §§261.24 and 261.33) in the uppermost aquifer. If sampling reveals
no contamination, the owner/operator may return to his original detection
protocol or enter into a consent agreement with EPA to follow a revised
protocol designed to avoid future false triggers. If, on the other hand,
contamination is confirmed, the owner/operator must begin characterizing
the rate and extent of migration.
Normally, assessment monitoring will require installation of addi-
tional well clusters located to define the vertical and horizontal extent
of the plume. Unlike detection monitoring where wells would be placed
more or less evenly along the downgradient border of the waste management
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area, wells in assessment monitoring could be concentrated in one area of
the site so as to track the migration of a localized discharge. In addition
to direct sampling for hazardous waste constituents, the owner/operator
may rely on indirect techniques, such as electrical resistivity or ground-
penetrating radar, to help define the boundaries of a plume.
Based on these techniques, the owner/operator must submit to EPA (as
soon as technically feasible), a written report assessing the quality of
ground water at the facility (§265.93(d)(5)). After this initial assess-
ment of ground-water contamination, the facility must continue assessment
monitoring at least quarterly until the facility closes or is permitted.
Additionally, the owner/operator must continue detection monitoring in any
wells unaffected by the initial leak (i.e., wells away from the edge of
the plume where no hazardous waste constituents have been detected or
wells around other non-leaking units).
It is important to note that no direct regulatory consequences flow
from a finding of contamination in assessment monitoring. The purpose of
assessment monitoring is strictly to acquire information to support future
decisions regarding the need for corrective action. The purpose does not
include determinations of whether or not such facilities are environmentally
acceptable. Strategies for cleaning up unacceptable contamination must be
developed through the permitting process or through enforcement action
under §3008(h), §7003, or under CERCLA §106.
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2.2 Permit Regulations for Ground-water Monitoring - Part 264, Subpart F
The primary goal of Part 264 ground-water monitoring is to ensure
that owners and operators of facilities handling hazardous waste detect any
release of contamination into ground water and take corrective action when
such contamination threatens human health or the environment. To achieve
this goal, the regulations establish a three-stage program designed to
detect, evaluate, and correct ground-water contamination arising from leaks
or discharges from hazardous waste management facilities. The program is
graduated so that the monitoring and clean-up responsibilities of the
owner/operator expand as the impact of the facility on ground water becomes
better understood.
2.2.1 Detection Monitoring
The first stage of the program, detection monitoring, is implemented at
facilities where no hazardous constituents are known to have migrated from
the facility to ground water. Applicants who are seeking permits for new
facilities or for interim status facilities that have not triggered into
assessment, would generally qualify for Part 264 detection monitoring (the
latter assumes, of course, that the interim status monitoring network is
adequate to detect contamination).
The actual monitoring requirements of Part 264 detection are similar to
those already imposed under the interim status regulations. In the preamble
to the regulations EPA expressed the expectation that properly designed
interim status networks would be sufficient for most permit detection
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systems. In Part 264 detection monitoring, however, the permittee routinely
monitors for a select set of indicator parameters specified in the permit
rather than for the four indicator parameters specified in the Part 265 reg-
ulations. Should the arrival of leachate from the facility be indicated
by an increase (or pH decrease) of any of the parameters relative to background,
the permittee must immediately sample for all constituents listed in Appendix
VIII in order to determine the chemical composition of the leachate.^ In
addition, the owner/operator must submit, within 180 days, an engineering
feasibility plan that outlines an approach for cleaning up ground water should
clean up prove necessary [§264.98(h)(5)]. The facility in turn is obliged
to move into the next phase of the Part 264 ground-water program - compliance
monitoring.
2.2.2 Compliance Monitoring
The goal of compliance monitoring is to ensure that leakage of hazardous
constituents (Part 261 Appendix VIII constituents) into ground water does not
exceed acceptable levels. Through the permit, therefore, the Agency and
the facility must specify what level of each constituent will be considered
environmentally acceptable and then establish a program of routine monitoring
to ensure that acceptable levels are not exceeded. If concentration limits
^ The Agency may use enforcement discretion so as not to require sampling
for those substances that are unstable in ground water or for which there
exists no EPA-approved test method. For a list of these substances see the
August 16, 1984 memo from Courtney Price and Lee Thomas entitled, "Enforcing
Ground-Water Monitoring Requirements in RCRA Part B Permit Applications."
The Agency has also proposed to waive monitoring requirements for such sub-
stances (See 49 FR 38786, October 1, 1984).
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are exceeded, the permittee must institute a corrective action program
designed to bring the concentration levels back within acceptable limits.
The permit writer establishes the framework for a compliance monitoring
program by incorporating a ground-water protection standard into the permit.
The standard consists of four elements, each of which must be specified in
the permit.
The first element of the standard is a listing of all Appendix VIII
hazardous constituents present in ground water that could reasonably have
been derived from the facility. The burden of demonstrating that a particular
Appendix VIII constituent could not reasonably be derived from a facility,
lies with the owner/operator. Claims of exclusion must be based on a
detailed chemical analysis of the facility's waste and must consider possible
chemical reactions that could occur in the facility or during the migration
of leachate into ground water. An exclusion is also available for an
individual constituent if the owner/operator can demonstrate that it is
incapable of posing a substantial present or potential hazard to human health
or the environment. Given this standard of proof, however, exclusions will
be granted rarely; the ground-water protection standard of most facilities,
therefore, will include all Appendix VIII constituents detected in ground
water.
The basis for identifying the Appendix VIII constituents present in
ground water will vary depending on the status of the facility at the time of
establishing the protection standard. Facilities that are operating under
detection monitoring permits will have identified the Appendix VIII consti-
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tuents present in ground water as part of their detection monitoring respon-
sibilities [see §264.98(h)(2)]. Facilities that have not yet received
permits and are operating under Part 265 assessment monitoring, however,
may have to perform additional sampling because assessment monitoring
requires the determination of Appendix VII substances rather than the full
complement of constituents listed in Appendix VIII. (Appendix VII is but a
subset of Appendix VIII - see section 3.3 for further explanation of this
point). Consequently, the facility owner in Part 265 assessment monitoring
will have to undertake additional sampling and analysis before the facility
can be permitted. [Note: the permit application regulations (Part 270)
require facilities to characterize plumes with respect to Appendix VIII
constituents (see §270.14(c)(4))].
The second element of the ground-water protection standard is the
specification of a concentration limit for each hazardous constituent
listed in the facility permit. Where possible, concentration limits must
be based on well established numerical concentration limits for specific
constituents. Where established standards are not available, the permit
writer must set concentration limits so as to prevent degradation of water
quality unless the owner/operator can demonstrate that a higher limit will
not adversely affect public health or the environment. Following this
approach, concentration limits must be set at either:
1) the maximum concentration limit for drinking water established
by the National Interim Primary Drinking Water Regulations
(where applicable);
2) the background level of the constituent in ground water; or
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3) an alternate concentration limit (ACL) if the owner/operator
can demonstrate that a higher concentration will not pose a
substantial present or potential hazard to human health or the
environment (§264.94).
The third and fourth elements of the ground-water protection standard
are the point of compliance and the compliance period. The compliance
point is the location at which the ground-water protection standard applies
and hence is the point where monitoring must occur. The regulations
specify that the point of compliance is the vertical surface located at
the downgradient limit of the waste management area (§264.95). The com-
pliance period is the period during which the ground-water protection
standard applies. This period is equal to the active life of the facility
plus the closure period [§264.96].
After the ground-water protection standard is established, the
permittee must monitor ground water to ensure that the facility continues
to comply with its protection standard. If properly designed and constructed,
the monitoring network established for detection monitoring should be
adequate for this purpose. In addition, the permittee must sample annually
for Appendix VIII constituents to detect any additional substances that
may have entered ground water. Should sampling reveal a new constituent,
the permit writer must amend the protection standard to include a concentra-
tion limit for the new constituent.
2.2.3 Corrective Action
If compliance monitoring reveals that a facility is exceeding its
ground-water protection standard (i.e., the concentration of a hazardous
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constituent in ground water exceeds the maximum limit established in the
permit), the facility must institute a corrective action program. The
goal of corrective action is to bring the facility back into compliance
with its protection standard. To achieve this goal, the facility must
develop a plan for removing the hazardous constituents or for treating the
constituents in place [§264.99(i)(2)]. If approved by the Agency, the
permit writer will incorporate this plan into the facility permit.
The permit writer must also include in the permit a program of ground-
water monitoring adequate to demonstrate the effectiveness of the corrective
action measures [§264.100(d)]. At the limit of the waste management area,
this program will be essentially the same as the compliance monitoring
program although permit writers may want to increase the number of wells
and the frequency of monitoring at or near the compliance point where the
plume appears to be concentrated. Also, owner/operators will be required
to install additional monitoring wells near the downgradient edge of the
plume so that the Agency can monitor the effectiveness of the corrective
action program.
The permittee must implement corrective action measures until compliance
with the ground-water protection standard is achieved. Once contamination
has been reduced below the concentration limit set in the permit, the facility
may discontinue corrective action measures and corrective action monitoring,
and return to the monitoring schedule established for compliance monitoring.
If compliance is not achieved before the end of the compliance period
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specified in the permit, the permittee must continue corrective action
until monitoring shows that the ground-water protection standard has not
been exceeded for three years [§264.100(f)].
2.3 Permit Application Regulations - Part 270
Part 270 of the regulations specifies the information an applicant
must submit to the Agency when applying for a permit. The information
requirements related to ground-water monitoring can be organized into two
basic groups. The first group, outlined in §270.14(c), establishes the
nature of the facility's impact on ground water, as well as the hydro-
geologic characteristics of the site's subsurface and the extent of the
waste management area. The second group includes the information necessary
to establish one of the three Part 264 ground-water monitoring and response
programs (detection monitoring, compliance monitoring, and/or corrective
action).
2.3.1 Information Requirements of §270.14(c)
Section 270.l4(c) includes four basic information requirements.
First, applicants must present the data collected during interim status
monitoring (where applicable). If the facility has implemented a satis-
factory monitoring system under interim status, these data should provide
information useful for determining whether hazardous constituents have
entered ground water. The Permit Applicant's Guidance Manual for Hazardous
Waste Land Treatment, Storage, and Disposal Facilities (May, 1984) states
that this provision requires submittal of background information to support
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these data as well as the data themselves. For example, the Applicant's
manual Instructs owner/operators to submit:
o a map showing the location of upgradient and downgradient
wells;
o a copy of the facility's sample and analysis plan;
o a description of the statistical procedure used in proces-
sing the data submitted;
o copies of water analysis results; and
o a description of the design and construction of each well.
Second, the applicant must identify the uppermost aquifer and hydraul-
ically interconnected aquifers beneath the facility property. The application
must indicate ground-water flow directions and provide the basis for the
aquifer identification (i.e. , a report written by a qualified hydrogeologist
on the hydrogeologic characteristics of the facility property supported by
at least the well drilling logs and available professional literature).
This information is needed to evaluate the adequacy of the ground-water
monitoring system that the applicant proposes to operate after the permit
is issued. (Readers are referred to the Permit Applicant's Manual for a
discussion of what constitutes an adequate hydrogeologic investigation;
additional guidance will be provided by the final TEGD).
Third, §270.]4(c)(3) requires the applicant to delineate the waste
management area, the property boundary, and the proposed point of compliance.
This information should be transposed onto a topographic map along with, to
the extent possible, the designation of the uppermost and any interrelated
aquifers.
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Finally, §270.14(c)(4) requires applicants to describe any plume of
contamination that has entered ground water by:
o delineating the extent of the plume; and
o identifying the concentration of each Appendix VIII
constituent throughout the plume or identifying the
maximum concentrations of each Appendix VIII con-
stituent in the plume.
This requirement applies to the following three categories of facilities:
1. Facilities where no interim status monitoring data are available
(e.g., waste piles, facilities that wrongly claimed a waiver
from interim status ground-water monitoring requirements);
2. Facilities whose interim status data indicate contamination; and
3. Facilities whose Part 265 detection monitoring system is inadequate
to determine whether or not a plume of contamination exists.
As the Permit Applicant's Guide indicates (page 9-42), the permit writer
will evaluate the ability of the facility's well network and sample and
analysis plan to determine the presence of a plume. If EPA determines that
the interim status monitoring program was inadequate to detect contamination,
the applicant will be instructed to provide the information required by
§270.14(c)(4).
2.3.2 Information Requirements for Appropriate Part 264 Ground-water System
Part 270 also requires permit applicants to submit information sufficient
to establish the appropriate ground-water monitoring program under Part 264.
The information requirements relevant to any particular facility depend on the
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status of that facility at the time of permitting. If monitoring conducted
pursuant to Part 265 and Section 270.14(c)(4) has not revealed contamination,
the applicant must submit the information, data, and analysis necessary to
implement a detection monitoring program. If monitoring has revealed the
presence of hazardous constituents in ground water at the point of compliance,
the applicant must outline a program of compliance monitoring and submit
a study that estimates the engineering feasibility of various forms of
corrective action [§270.14(c)(7)]. Where the concentration of a hazardous
constituent exceeds background or an alternate concentration level proposed
by the applicant, (s)he must instead submit a detailed plan for corrective
action and a description of the monitoring program intended to demonstrate
the adequacy of the corrective measures [§270.14(c)(8)]. Detail concerning
the specific information required to support each type of monitoring program
is provided in the regulations and expanded upon in the Permit Applicant's
Guidance Manual §§ 9.6 - 9.8.
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CHAPTER 3
REGULATORY COMPARISONS
In order to devise enforcement strategies that are consistent with
and supportive of the permitting process, it is important to have an under-
standing of how the Parts 265 and 264 ground-water monitoring regulations
interrelate. As mentioned previously, the Agency envisioned the interim
status period as a time in which to develop, among other things, the infor-
mation necessary to support permitting. Indeed, one of the overall goals
of interim status monitoring was to generate the data necessary to decide
whether the facility permit should include a detection monitoring program,
a compliance monitoring program, or a program for corrective action.
In short, the Agency envisioned a smooth transition from interim status
detection monitoring, through assessment, to final permitting. A facility
would proceed from one phase of monitoring to the next by building upon the
monitoring system implemented during the previous stage. While interim
status monitoring focused on a smaller number of constituents in order to
limit the routine monitoring obligations of the owner/operator, the Agency
never considered the physical well networks of the Part 265 and Part 264
programs fundamentally different. Sampling protocols and schedules would
change to be consistent with the new objectives of each monitoring phase,
but the physical well network (if properly designed) could serve throughout
the life of a facility. A Part 265 detection system, for example, may
need to be expanded to meet the needs of compliance monitoring, but with
proper foresight, the existing wells need not be replaced.
3-1
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Unfortunately, certain interim status monitoring systems are insufficient
in quality and breadth to meet the Part 265 standards. Of those that meet
the minimum standards, few have been designed in expectation of the facility's
future monitoring obligations. As a result, facilities that should be
close to meeting their Part 264 ground-water obligations, are in fact not
prepared for the permitting process.
If enforcement officials are going to help bridge this gap, they must
have a thorough understanding of exactly how the Part 265 and Part 264
regulations interrelate. To aid officials in this effort, this chapter
will outline the major similarities and differences between the requirements
of three ground-water monitoring programs: Part 265 detection vs. Part 264
detection; Parts 264/265 detection vs. compliance monitoring; and Part 265
assessment monitoring vs. plume characterization activities conducted pursuant
to §270.14(c)(4).
3.1 Part 265 vs. Part 264 Detection Monitoring
3.1.1 Well Placement
For all practical purposes, the requirements governing well placement
are the same for both Part 265 and Part 264 detection monitoring. Whereas the
regulatory language differs slightly, a network designed to meet the Part 265
standard should be substantially the same (in terms of well locations and
depths) as one designed to meet the Part 264 standard.
Both programs include a performance standard for background well place-
ment that requires a sufficient number of wells, installed at appropriate
3-2
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locations and depths, to yield ground-water samples that are: 1) representative
of the background water quality in the uppermost aquifer; and 2) unaffected
by leakage from the facility [Compare §265.91(a)(l) with §264.97(a)(l) and
§264.97(a)(2)].
Both programs also include similar language regarding the placement of
downgradient wells, although the Part 265 regulations require placement at
the "limit of the waste management area," whereas the Part 264 regulations
require placement at the "point of compliance" [cf., 265.91(a)(2) and
264.97(a)(2)]. While worded differently, the physical well location dictated
by both programs is, by definition, essentially the same. The regulations
define the "waste management area" as "the limit projected in the horizontal
plane of the area on which waste will be placed during the active life of a
regulated unit" [§264.95(b)],5 Where there is more than one unit at a facility,
the waste management area is described by an imaginary line circumscribing
the various units. Hence, wells in Part 265 detection monitoring must be
placed at the edge of the waste management area.
5 The Permit Applicant's Manual further qualifies this definition by
noting that for Part 265 systems, EPA will evaluate the areal extent of the
waste management area at an expanding facility against the regulatory man-
date to choose well locations so as "to immediately detect" the migration
of hazardous waste into the uppermost aquifer. For permit applications,
EPA will evaluate the proposed waste management area against the policy of
designing monitoring programs so as to give an early warning of the release
of contaminants. In either case, EPA does not recommend that facility
owners propose a waste management area whose limit is geographically remote
from the active waste handling zone. Rather, monitoring wells should be
closely associated with the active zone even if this means redefining the
waste management area as a facility expands.
3-3
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Wells in Part 264 detection must also be placed at the edge of the
waste management area because the point of compliance is, by definition,
the edge of the waste management area projected downward into the uppermost
aquLfer [see §264.95(a)]. The point of compliance is, therefore, the limit
of the waste management area described in three dimensional space (See
Figure 3.1). Both regulations mandate, consequently, that wells are located
along the same thin land surface. Parts 265 and 264 similarly require
well spacings and depths capable of detecting statistically significant
contamination in the uppermost aquifer.
Figure 3.1
RELATIONSHIP OF THE WASTE MANAGEMENT AREA
TO THE POINT OF COMPLIANCE
LIMIT OF THE
WASTE MANAGEMENT
AREA
4- SURFACE IMPOUNDMENT
4-
THREE DIMENSIONAL
POINT OF COMPLIANCE
UPPER MOST AQUIFIER
GROUND-WATER
FLOW
3-4
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3.1.2 Indicator Parameters
The concept of sampling for parameters designed "to indicate contami-
nation" is the same for both Parts 265 and 264 detection monitoring. The
Part 265 regulations mandate the use of four specific indicators for all
facilities, whereas the Part 264 regulations require the permit writer to
specify a set of site-specific indicator parameters in each facility permit.
The greater latitude and scope afforded by the Part 264 regulations
allows the permit writer to design the detection program around the partic-
ulars of a specific facility. Rather than rely on broad, generic measures
such as TOG, the permit writer can compel sampling for specific constituents
known to be in the facility's waste. As a result, a Part 264 detection
system can be designed to be more sensitive than the Part 265 system speci-
fied in the interim status regulations.
3.1.3 Sampling Frequency
Both the Part 265 and Part 264 regulations require quarterly sampling
for one year to establish background, and at least semi-annual sampling
thereafter.
3.1.4 Appropriate Sampling Techniques
The choice of the sampling device and the appropriateness of the materials
used in the device are dictated by the needs of the most sensitive constituent
of interest. In general, the most sensitive constituents will be volatile
3-5
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organics because as a class, volatile organics are highly susceptible to
degassing and chemical interference with sampling-device materials (e.g.,
silicon tubing). For most monitoring applications, therefore, the sampling
device will be chosen to meet the needs of volatile organics.
Given that the Part 265 detection program necessarily includes a volatile
organic parameter, TOX, that can be measured reliably at the 5 ppb level (see
Method 9020 in "Test Methods for Evaluating Solid Waste, SW-846), sample
device selection for interim status monitoring will always be dictated by
the needs of volatile organics. Therefore, if a Part 264 detection program
includes sampling for any volatile organic, then the sampling devices and
materials appropriate for each program would be the same. Considering that
264 detection systems almost always contain at least one volatile organic
indicator, the sampling requirements of both 265 and 264 detection monitor-
ing will be essentially equivalent in most cases.
It is conceivable, however, that a sampling device appropriate for Part
264 sampling would NOT be appropriate for Part 265 detection if the permit
writer did not require sampling for any volatile organics (e.g., if the
facility were a monofill of hexavalent chromium and the permit writer elected
chromium as the only Part 264 detection parameter). Such a facility could
use a sampling device normally inappropriate for measuring volatile organics.
If, however, a chromium waste facility ever detected contamination, the
regulations require the owner/operator to sample immediately for the conti-
ituents listed in Appendix VIII (including many volatile organics). The
3-6
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facility owner, therefore, would have to change sampling devices to ensure
that he acquired representative samples.
Recognizing this fact, it may be in the best interest of the owner/
operator to consider his/her long-term monitoring needs when purchasing sampling
equipment. To the extent that facility owners purchase and use equipment for
detection monitoring that will still be suitable should leakage occur, the
sampling mechanisms appropriate for 265 and 264 detection monitoring once
again converge.
3.1.5 Statistical Comparisons
Both the Parts 265 and 264 detection monitoring regulations require the
owner/operator to determine whether there has been a statistically significant
increase over background for any indicator parameter specified in the
program (or decrease for pH).
The statistics used to make this determination, however, vary between the
programs in two important ways. First, the Part 264 detection program requires
the owner/operator to use a specific Student's t-test when defining significance
(the Cochran's Approximation to the Behrens Fisher Students t-test), unless he
can defend another statistical technique as substantially equivalent. The Part
265 program, on the other hand, makes no allowance for an alternate statistical
technique, but the regulations do not specify a particular variant of the Student's
t-test; any Student's t-test is acceptable.
Second, the Part 264 detection regulations require the test to be applied
to the .05 level of significance, while the 265 regulations specify a signifi-
3-7
-------
cance level of .01. The level of significance sets the balance between
the chances of the test falsely detecting contamination ("false positive")
and the test failing to identify contamination that has occurred.6 By
raising the level of significance for the Part 264 standards, the Agency
achieved greater assurance that the test would not fail to detect actual
contamination. During the interim status period, the Agency was willing to
reduce the chances of "false positives" by accepting a slightly higher prob-
ability of failing to detect leakage. This balance was acceptable for interim
status because the Agency knew it would have another opportunity to investigate
possible leakage during the permit application process. For the permit
regulations, however, the Agency decided that a lower level of significance
would unduly compromise the ability of the test to detect contamination.
3.2 Part 264 Detection Monitoring vs. Part 264 Compliance Monitoring
3.2.1 Well Placement and Network Design
Well placements for compliance monitoring more closely resemble
detection monitoring networks than they do assessment networks. One should
not assume that network configurations for compliance monitoring will resemble
configurations suitable for Part 265 assessment monitoring simply because both
programs represent a second phase of monitoring after detection monitoring.
In fact, in some cases the network installed for detection monitoring will
6 Readers should note that this discussion pertains to the false positive
rate caused by the statistical test alone. Many other factors, such as insuffi-
cient number of background wells, can cause a facility to trigger under detection
monitoring when contamination has not actually occurred. In fact, many "false
positives" are not a function of statistics, but are a function of such things as
well location, sampling, and chemical analysis.
3-8
-------
become the compliance monitoring network; all that will change is the sampling
protocol and the objective of the monitoring program.
Given that compliance monitoring is meant to evaluate contamination rather
than just detect it, there is a strong possibility that existing detection net-
works may have to be expanded to meet the broader objectives of compliance
monitoring. The more complicated statistical techniques used to evaluate
monitoring data during compliance monitoring, for example, may require a
greater number of background wells than the statistical approach used during
detection monitoring. Likewise, the permit writer may want to require
additional downgradient wells in the immediate vicinity of those wells where
contamination has been detected.
Additional wells are generally most appropriate when contamination has
been detected in only one or two monitoring wells, indicating a localized
leak. With localized leaks, only a limited amount of dispersion can occur
before the plume passes the point of compliance (see Figure 3.2). As a
result, more wells may be necessary to ensure that measurements of contami-
Figure 3.2
GROUND-WATER
FLOW
LEGEND:
0 EXISTING MONITORING WELL
Q PROPOSED MONTORING WELL
CONTAMINANT PLUME
LINED SURFACE
IMPOUNDMENT
BREAK IN THE
LINER
FUTURE LOCATION OF
COMPLIANCE MONITORING
WELL
TRIGGERING WELL
3-9
-------
nation represent the high concentrations characteristic of the plume's center,
rather than the lower concentrations normally found in the plume's periphery.
In short, in some circumstances an existing detection system may have to
be expanded under compliance monitoring, but the general well configurations
for detection monitoring and compliance monitoring are the same.
3.2.2 Establishing Background Concentrations
The regulations specify that background concentrations for Part 265 and
Part 264 detection indicator parameters must be based on quarterly samples for
one year. Under compliance monitoring, however, the regulations grant the
permit writer leeway on how to establish background. (Recall that background
values are very important in compliance monitoring because in many instances,
these background values will be incorporated into the ground-water protection
standard as "concentration limits.")
The permit writer has two options for establishing background
values for compliance monitoring constituents. The permit writer may
establish concentration limits based on the mean of pooled background data
available at the time of permitting. To ensure that sufficient data are
available for this purpose, the permit writer may require the applicant to
undertake an accelerated program of background sampling prior to permitting.
Alternately, if there is a high temporal correlation between up- and
downgradient concentrations, the permit writer may specify that background
values be established by sampling upgradient wells each time ground water is
sampled at the point of compliance. With this approach, background concentra-
3-10
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tions are not established by averaging values obtained over time; rather,
background values are established anew after each sampling event.
3.2.3 Sampling Frequency
Since hazardous constituents are already present in ground water when
compliance monitoring begins, the regulations require a more aggressive sampling
schedule for compliance monitoring than for detection monitoring. Under
detection monitoring, the regulations state that sampling for indicator
parameters should occur at least twice a year (once background is established)
[§265.92(d)(2>]. By contrast, the compliance monitoring regulations require
routine sampling of the hazardous constituents listed in the facility's
protection standard at least quarterly.
3.2.4 Statistical Comparisons
Whereas the regulations specify the use of a specific t-test protocol
when evaluating monitoring data obtained during detection monitoring, they
do not detail specific procedures for use during compliance monitoring. The
compliance monitoring regulations require that the statistical procedures
used be appropriate for the distribution of data encountered and provide a
reasonable balance between the probability of falsely identifying and failing
to identify violations of the ground-water protection standard.
Moreover, unlike detection monitoring, the compliance monitoring
regulations do not establish a particular level of significance for use
when making comparisons. The high number of comparisons likely in most
compliance monitoring programs will increase the probability of false
3-11
-------
positives; therefore, permit writers are granted the latitude to choose a
level of significance that will strike an appropriate balance between the
probability of false positives and false negatives.
3.3 Part 265 Assessment Monitoring vs. §270.14(c)(4) Plume Characterization
Both Part 265 assessment monitoring and §270.14(c)(4) require facility
owners to assess any plume of contamination that has entered ground water.
The programs differ, however, in two important ways.
First, the Part 265 assessment program applies only to facilities that
have detected the existence of a plume through Part 265 ground-water monitoring,
The §270.14(c)(4) requirements, on the other hand, apply to any facility
that has not demonstrated the absence of contamination through proper Part
265 monitoring.
Second, Part 265 assessment requires monitoring for hazardous wastes or
"hazardous waste constituents" [see §265.93(d)(4)], whereas §270.14(c)(4)
requires sampling for "hazardous constituents." "Hazardous constituents"
are those substances listed in Appendix VIII of Part 261. "Hazardous waste
constituents," as defined in §260.10, are the constituents that provided the
basis for listing each of the hazardous wastes identified in Part 261 Sub-
part D, or a constituent listed in Table 1 of §261.24 (constituents with
National Interim Drinking Water Standards under the Safe Drinking Water
Act).
Appendix VII identifies the specific constituent(s) responsible for
the listing of wastes from the non-specific sources in §261.31 as well as
3-12
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from the specific sources contained in §261.32. In the case of any of the
discarded commercial chemical products, off-specification products, and
spill residues listed in §261.33, the chemical product itself is considered
the constituent responsible for the listing of the substance in Part 261.
Interim status assessment monitoring, therefore, requires the owner/
operator to sample for any Appendix VII constituent, any substance listed in
§261.33, or any substance listed in §261.24 that is in the facility's waste.
Section 270.14(c)(4), on the other hand, requires sampling for the full comple-
ment of Appendix VIII constituents.
This difference between the two programs is significant. Part 265 "s
reliance on "hazardous waste constituents" rather than on Appendix VIII
constituents could mean that certain constituents in a facility's waste
would not be included in a Part 265 assessment monitoring program.
A number of factors may be responsible for the exclusion of certain
constituents. First, the constituents identified in Appendix VII as the
basis for listing individual wastes in Part 261, are not necessarily a complete
list of all hazardous constituents contained in each waste. In developing
Appendix VII, EPA did not attempt to conduct an exhaustive analysis of all
constituents in the waste that could have provided a basis for the listing
(§261.11 provides the criteria the Administrator must use when listing a
waste). Rather, the Agency identified a few of the more commonly known consti-
tuents in each waste that could pose a substantial present or potential hazard
to human health or the environment.
3-13
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Second, Appendix VII only applies to listed wastes; it does not address
hazardous constituents that may be present in wastes deemed hazardous because
they exhibit one of the characteristics in Part 261. Table 1 of §261.24
addresses wastes exhibiting the characteristic of E.P. toxicity, but "hazardous
waste constituents" do not include non-listed wastes deemed hazardous because
of corrosivity, reactivity, or ignitability. Moreover, Appendix VII and
Table 1 of §261.24 were not developed to address the constituents that may be
formed when various wastes are mixed in a regulated unit, or when wastes react
with constituents in the soil. As a result, a Part 265 assessment program
could conceivably fail to include a consitituent of concern at a particular
facility. It must be recalled, however, that the interim status regulations
were designed to be self-implementing, not exhaustive. '
1 Chapter 4 explores the various enforcement authorities available to
compel sampling for Appendix VIII constituents at interim status land disposal
facilities if such sampling appears necessary. Depending on the circumstances,
a §3008(a) order enforcing §270.14 (c)(4), a §3013 order or a §3008(h) may be used
(See section 4.1.1 for further explanation).
3-14
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CHAPTER 4
OVERVIEW OF ORDER AUTHORITIES
There are a variety of order authorities available to correct ground-
water problems at RCRA hazardous waste facilities. Section 3008(a) of RCRA
provides for the issuance of orders and for the commencement of civil suits
when any requirement of Subtitle C is violated. RCRA also establishes
enforcement authorities under Sections 3004(v), 3008(h), 3013, and 7003.
Any of these authorities may be used, in certain circumstances, to address
ground-water problems. In addition, the enforcement authority in §106 of
CERCLA may be available in many cases.8
While there will undoubtedly be instances where it is most appropriate
to file a civil suit under §3008(a), §3008(h), or §7003, or to initiate
criminal proceedings under §§3008(d) and (e), there are three order author-
ities that should prove most useful in addressing inadequate ground-water
monitoring programs:
o §3008(a) orders seeking penalties and/or injunctive relief
for violations of Part 265 Subpart F and Part 270;
o §3008(h) orders seeking the investigation and implementation of
corrective action for releases of hazardous waste or hazardous
constituents; and
o §3013 orders seeking monitoring, investigations, analyses,
and reporting by facilities that the Administrator has deter-
mined may present a substantial hazard to human health or the
environment.
8 For further information on the applicability and scope of CERCLA 106
orders, see the September 8, 1984 memo on the "Use and Issuance of Administra-
tive Orders under §106(a) of CERCLA" from Lee Thomas and Courtney Price.
4-1
-------
This chapter will compare these three order authorities and will describe
some of the factors that enforcement officials should consider when selecting
which authority(ies) to use to compel a specific remedy.
4.1 Comparison of §3008(a), §3008(h), and §3013 Orders
The table on the two following pages presents a comparison of §3008(a),
§3008(h), and §3013 orders with respect to the types of actions that the
orders may compel, the types of situations that may trigger the issuance of
an order, the burden of proof the Agency must satisfy, whether there are
formal administrative proceedings that must be followed, and any special
features of the authority (e.g., the ability to assess penalties). The
section of the chart dealing with §3008(a) orders is divided into the follow-
ing three segments:
o §3008(a) enforcing Part 265 detection monitoring
o §3008(a) enforcing Part 265 assessment monitoring
o §3008(a) enforcing Part 270 requirements.
4.1.1 Actions the Orders May Require
As shown in Table 4.1, a §3008(a) order enforcing Parts 265 and 270 can
be used to require the following general categories of ground-water-related
activities:
o a thorough hydrogeologic characterization of the site;
o design and installation of a well network capable of
immediately detecting contamination from the facility;
o specification of well drilling and development methods
as well as casing materials;
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o sampling for any parameter listed in Appendix VII or VIII of
Part 261 or Appendix III of Part 265, or specified in §265.92
(chloride, iron, manganese, phenols, sodium, sulphate, pH, specific
conductance, total organic carbon, and total organic halogen); and
o a design of the ground-water monitoring system that would be
operated after the permit is issued.
Section 3008(h) and §3013 orders can in many cases be used to obtain
the same baseline injunctive relief available under §3008(a). More signifi-
cantly, orders issued under §3008(h) and §3013 may be used to address contam-
ination of media other than ground water and releases from solid waste manage-
ment units. Further, §3008(h) can be used to go beyond the investigation
and monitoring stage to require actual clean up of releases into the environ-
ment.
One caution with respect to §3013 and §3008(h) orders is that they may
compel only those actions that are needed to investigate or address a release
of hazardous waste or hazardous constituents [§3008(h)j or a substantial
hazard [§3013]. While there will be cases in which the issuance of orders
under those authorities is appropriate, it may in some cases be necessary
to issue a simultaneous §3008(a) order to obtain compliance with Part 265/270
requirements. Further, penalties for violations of Parts 265 and 270 may be
assessed only through issuance of a §3008(a) order.
4.1.2 Conditions for Order Issuance
§3008(a) Orders
A §3008(a) order may be issued only for violation of one or more Subtitle C
requirements. Therefore, when enforcement personnel and the permit writer
4-5
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determine a facility's ground-water monitoring program to be technically
inadequate, enforcement personnel should determine whether any of the technical
inadequacies constitute violations of Part 265 Subpart F or Part 270.9
In some cases the regulations are specific as to what findings of fact
would indicate violations. For example, if an owner/operator has installed
only two downgradient wells, the facility is clearly out of compliance with
§265.91(a)(2) of the regulations, the section that requires installation of
at least three downgradient wells. Likewise, if a facility does not have
some of the records specified in the regulations (e.g., an assessment outline),
or has not performed some of the required analyses, then the owner is clearly
in violation. The decision concerning the existence of a violation becomes
more involved when it is based upon evaluating the adequacy of a facility's
ground-water monitoring system beyond the minimum requirements.
In great part, the heightened level of analysis required to evaluate
the overall adequacy of a system evolves from the regulations' reliance on
broad performance standards. Given the great variability between sites in
terms of wastes handled, hydrogeology, and climate, it is impossible to
design a regulatory system that defines for all cases exactly what constitutes
an adequate ground-water monitoring program. As a result, the Agency relies
on performance standards to define "adequate."
9 As cited, herein, references to Part 265, Subpart F and Part 270 include
requirements of authorized State programs.
4-6
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The performance-oriented provisions of Subpart F set high standards for
interim status ground-water monitoring systems, and enforcement personnel
should not underestimate the power and applicability of this language. For
example, even though the regulations establish a minimum of one background
monitoring well, a single well is seldom sufficient because owner/operators
must design their systems to meet the background-well performance standard
listed in §265.91(a)(1). Section 265.91(a)(l) requires owner/operators to
install a sufficient number of wells at appropriate locations and depths to
yield samples representative of background water quality not affected by the
facility. If a facility's well array does not meet this standard, the owner/
operator is out of compliance with the regulations. Figure 4.2 summarizes
the Part 265 and Part 270 performance standards relating to ground-water
monitoring.
Figure 4.3, on pages 4-9 through 4-14, illustrates in greater detail
the relationship between certain technical inadequacies of ground-water
monitoring programs and the regulatory performance standards of RCRA. The
left-hand side of the table lists a series of standards that must be met in
order to meet the the performance standards summarized in Figure 4.2 (e.g,,
background-well samples must be unaffected by the facility). The middle
column includes examples of technical inadequacies that could prevent a
system from meeting the left-hand standards and therefore could represent a
violation of one or more of the performance standards (e.g., failure to
consider flow paths of dense immiscibles when locating background wells).
Finally, the right-hand column lists for each technical inadequacy the
performance standard(s) that may have been violated.
4-7
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FIGURE 4.2
GROUND-WATER PERFORMANCE STANDARDS
PARTS 265 and 270
CITATION
STANDARD
S265.90(a)
the owner/operator of a land disposal facility must implement a
ground-water monitoring program "capable of determining the facility's
impact on the quality of ground water in the uppermost aquifer
underlying the facility,..." (emphasis added)
§265.91(a)
a ground-water nonitoring system "must be capable of yielding
ground-water samples for analysis..."
§265.91(a)(l)
the number, locations, and depths of background ironitoring wells
must be "sufficient to yield ground-water samples that are:
(i) Representative of background ground-water quality in the
uppernost aquifer near the facility; and
(ii) Not affected by the facility..."
§265.91(a)(2)
the number, locations, and depths of downgradient monitoring wells
must ensure that they "immediately detect any statistically significant
amounts of hazardous waste or^ hazardous waste constituents that
migrate from the waste management area to the uppernost aquifer."
(emphasis added)
§265.93(d)(4)
§270.14(c)(2)
an assessment monitoring plan must be capable of determining:
"(i) Whether hazardous waste or hazardous waste constituents
have entered the ground water;
(ii) The rate and extent of migration of hazardous waste or
hazardous waste constituents in the ground water..."
the Part B applicant must submit, among other things, an "identifica-
tion of the uppermost aquifer and aquifers hyiraulically interconnected
beneath the facility property, including ground-water flow direction
and rate, and the basis for such identification (i.e., the informa-
tion obtained from hydrogeologic investigations of the facility
area)." (emphasis added)
S270.14(c)(4)
the Part B applicant must include in the submittal a "description of
any plume of contamination that has entered the ground water from a
regulated unit at the time that the application was submitted that:
(i) delineates the extent of the plume...,
(ii) identifies the concentration of each Appendix VIII...
constituent...throughout the plume..." (emphasis added)
4-8
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FIGURE 4.3
RELATIONSHIP OF TECHNICAL INADEQUACIES TO GROUND-WATER
PERFORMANCE STANDARDS
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
1. Uppermost Aquifer must
be correctly identified
2. Ground-water flow
directions and rates must
be properly determined
• failure to consider aquifers
hydraulically interconnected to the
uppermost aquifer
incorrect identification of certain
formations as confining layers or
aquitards
failure to use test drilling and/or
soil borings to characterize sub-
surface hydrogeology
• failure to use piezometers or wells
to determine ground-water flow
rates and directions (or failure to
use a sufficient number of them)
• failure to consider temporal varia-
tions in water levels when
establishing flow directions (e.g.,
seasonal variations, short-term
fluctuations due to pumping)
• failure to assess significance of
vertical gradients when evaluating
flow rates and directions.
• failure to use standard/consistent
benchmarks when establishing
water level elevations
failure of the O/O to consider the
effect of local withdrawal wells on
ground-water flow direction
failure of the O/O to obtain suffi-
cient water level measurements
Regulatory
Citations
§265.90(a)
§265.91(8X1)
§270.14(c)(2)
§265.90(a)
§265.91(8X1)
(a)(2)
§270.14(cX2)
§265.90(a)
§265.91(a)(1)
§270.14(c)(2)
§265.90(a)
§265.91(a)(1)
§270.14(c)(2)
§290.90(a)
§295.91(a)(1)
§270.14(c)(2)
§265.90(3)
§295.91(8X1)
(a)(2)
§270.14(c)(2)
§265.90(3)
§265.91(8X1)
§270.14(c)(2)
§265.90(a)
§265.91(a)(1)
§265.90(3)
§265.91(8X1)
4-9
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FIGURE 4.3 (continued)
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
Regulatory
Citations
3. Background wells must
be located so as to yield
samples that are not
affected by the facility
• failure of the O/O to consider the §265.90(a)
effect of local withdrawal wells on §265.91(a)(1)
ground-water flow direction
• failure of the 0/0 to obtain suffi- §265.90(a)
cient water level measurements §265.91(a)(1)
• failure of the O/O to consider flow §265.90(a)
path of dense immiscibles in §265.91(a)(1)
establishing upgradient well
locations
• failure of the O/O to consider §265.90(a)
seasonal fluctuations in ground- §265.91(a)(1)
water flow direction
• failure to install wells hydraulically §265.90(a)
upgradient, except in cases where §265.91(a)(1)
upgradient water quality is
affected by the facility (e.g.,
migration of dense immiscibles in
the upgradient direction, mound-
ing of water beneath the facility)
• failure of the 0/0 to adequately §265.90(a)
characterize subsurface §265.91(a)(1)
hydrogeology
• wells intersect only ground water §265.90(a)
that flows around facility §265.91 (a)(1)
4. Background wells must
be constructed so as to
yield samples that are
representative of in-situ
ground-water quality
• wells constructed of materials that
may release or sorb constituents
of concern
• wells improperly sealed—con-
tamination of sample is a concern
• nested or mulitple screen wells
are used and it cannot be
demonstrated that there has been
no movement of ground water
between strata
• improper drilling methods were
used, possibly contaminating the
formation
• well intake packed with materials
that may contaminate sample
§265.90(a)
§265.91(a)
§265.90(3)
§265.91(a)
§265.91 (c)
§265.90(a)
§265.91 (a)(1)
§265.91 (a)(2)
§265.90(3)
§265.91(3)
§265.90(3)
§265.91(3)
§265.91(C)
4-1
-------
FIGURE 4.3 (continued)
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
Regulatory
Citations
Background wells must be
constructed so as to yield
samples that are represen-
tative of in-situ ground-water
quality, (continued)
• well screens used are of an inap- §265.90(a)
propriate length §265.91 (a)(1)
§265.91 (a)(2)
• wells developed using water other §265.90(a)
than formation water §265.91 (a)
• improper well development §265.90(a)
yielding samples with suspended §265.91 (a)
sediments that may bias chemical
analysis
• use of drilling muds or nonforma- §265.90(a)
tion water during well construction §265.91 (a)
that can bias results of samples
collected from wells
5. Downgradient monitoring
wells must be located so as
to ensure the immediate
detection of any contamina-
tion migrating from the
facility
6. Downgradient monitoring
wells must be constructed
so as to yield samples that
are representative of in-situ
ground-water quality
• wells not placed immediately adja- §265.90(a)
cent to waste management area §265.91(a)(2)
• failure of O/O to consider poten- §265.90(a)
tial pathways for dense §265.91(a)(2)
immiscibles
• inadequate vertical distribution of §265.90(a)
wells in thick or heavily stratified §265.91(a)(2)
aquifer
• inadequate horizontal distribution §265.90(a)
of wells in aquifers of varying §265.91(a)(2)
hydraulic conductivity
• likely pathways of contamination §265.90(a)
(e.g., buried stream channels, §265.91(a)(2)
fractures, areas of high
permeability) are not intersected
by wells
• well network covers uppermost §265.90(a)
but not interconnected aquifers §265.91(a)(2)
See #4
4-11
-------
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
Regulatory
Citations
7. Samples from
background and down-
gradient wells must be
properly collected and
analyzed
failure to evacuate stagnant water
from the well before sampling
failure to sample wells within a
reasonable amount of time after
well evacuation
• improper decisions regarding
filtering or non-filtering of samples
prior to analysis (e.g., use of filtra-
tion on samples to be analyzed
for volatile organics)
• use of an inappropriate sampling
device
use of improper sample preserva-
tion techniques
• samples collected with a device
that is constructed of materials
that interfere with sample integrity
• samples collected with a non-
dedicated sampling device that is
not cleaned between sampling
events
• improper use of a sampling
device such that sample quality is
affected (e.g., degassing of sam-
ple caused by agitation of bailer)
§265.90(a)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(a)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(a)
§265.93(d)(4)
§270.14(c)(4)
§265.90(a)
§265.92(a)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
4-12
-------
FIGURE 4.3 (continued)
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
Regulatory
Citations
Samples from background
and downgradient wells
must be properly collected
and analyzed (continued)
• improper handling of samples
(e.g., failure to eliminate
headspace from containers of
samples to be analyzed for
volatiles)
• failure of the sampling plan to
establish procedures for sampling
immiscibles (i.e., "floaters" and
"sinkers")
• failure to follow appropriate
QA/QC procedures
failure to ensure sample integrity
through the use of proper chain-
of-custody procedures
failure to demonstrate suitability of
methods used for sample analysis
(other than those specified in
SW-846)
failure to perform analysis in the
field on unstable parameters or
constituents (e.g., pH, Eh, specific
conductance, alkalinity, dissolved
oxygen)
use of sample containers that
may interfere with sample quality
(e.g., synthetic containers used
with volatile samples)
failure to make proper use of
sample blanks
§265.90(a)
§265.92(a)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(a)
§265.93(d)(4)
§270.14(c)(4)
§265.90(a)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(3)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
§265.90(a)
§265.92(3)
§265.93(d)(4)
§270.14(c)(4)
4-13
-------
Examples of Basic
Elements Required
by Performance
Standards
Examples of Technical
Inadequacies that may
Constitute Violations
Regulatory
Citations
8. In Part 265 assessment
monitoring the O/O must
sample for the correct
substances
9. In defining the Appendix
VIII makeup of a plume the
O/O must sample for the
correct substances
10. In Part 265 assessment
monitoring and in defining
the Appendix VIII makeup of
a plume the O/O must use
appropriate sampling
methodologies
11. Part B applicants who
have either detected con-
tamination or failed to imple-
ment an adequate part 265
GWM program must deter-
mine with confidence
whether a plume exists and
must characterize any
plume
failure of the O/O's list of sam- §265.93(d)(4)
pling parameters to include cer-
tain wastes that are listed in
§261.24 or §261.33, unless ade-
quate justification is provided
failure of the O/O's list of sam- §265.93(d)(4)
pling parameters to include
Appendix VII constituents of all
wastes listed under §§261.31 and
261.32, unless adequate justifica-
tion is provided
failure of the O/O's list of sam- §270.14(c)(4)
pling parameters to include all
Appendix VIII constituents, unless
adequate justification is provided
failure of sampling effort to iden- §265.93(d)(4)
tify areas outside the plume §270.14(c)(4)
number of wells was insufficient §265.93(d)(4)
to determine vertical and horizon- §270.14(c)(4)
tal gradients in contaminant
concentrations
total reliance on indirect methods §265.93(d)(4)
to characterize plume (e.g., elec- §270.14(c)(4)
trical resistivity, borehole
geophysics)
failure of O/O to implement a §270.14(c)(4)
monitoring program that is
capable of detecting the existence
of any plume that might emanate
from the facility
failure of O/O to sample both §270.14(c)(4)
upgradient and downgradient
wells for all Appendix VIII
constituents
See also items #1, #2
4-14
-------
The technical inadequacies in Figure 4.3 are not necessarily violations
in all cases. They are violations only when they result in a failure of the
facility to meet one or more of the performance standards. Further, the
list of technical inadequacies is not meant to be exhaustive. To a certain
degree, the decision as to whether a facility's monitoring program is adequate
must be made on a case-by-case basis.
§3013 Orders
Section 3013 orders may be issued to a facility only when the Admini-
strator determines that the presence or release of hazardous waste at the
facility may present a substantial hazard to human health or the environment.
The facility need not be violating RCRA regulations to qualify for action
under §3013.
Actual physical evidence of contamination is not necessary to support a
§3013 order. In the case of a facility that has not conducted any ground-water
monitoring activities, the potential for release of hazardous waste, the
nature of the site's underlying hydrogeology, and the proximity of an aquifer
or populated area will usually be sufficient, with expert opinion, to support
a §3013 order. In some cases, the Region may wish to use §3007 authority to
sample one or more wells at a facility in order to provide direct evidence
of a release. Given that direct evidence is often unnecessary to establish
the applicablity of §3013, the Region should probably avoid direct sampling
unless it is confident that existing wells will intersect the suspected
plume. Guidance issued September 26, 1984 provides further discussion of
the grounds for issuance of §3013 orders. (See memo from Courtney Price and
4-15
-------
Lee Thomas entitled, "Issuance of Administrative Orders Under Section 3013
of the Resource Conservation and Recovery Act").
§3008(h) Orders
Section 3008(h) of RCRA provides that the Administrator may issue an
order or file a civil suit requiring corrective action or other appropriate
response measures whenever (s)he determines that there is or has been a
release of hazardous waste into the environment. Section 3008(h) actions are
not limited to violations of RCRA.
As described in the September 1985 draft guidance on the scope and use
of §3008(h), the Agency is interpreting the term "release" to include any
spilling, leaking, pumping, pouring, emitting, erupting, discharging, inject-
ing escaping, leaching, dumping, or disposing into the environment. To show
that a release has occurred, the Administrator does not necessarily need
sampling data. Such evidence as a broken dike at a surface impoundment
should also support a determination that a release has occurred. In some
cases, information on the contents of a land disposal unit, along with infor-
mation on the site hydrogeology and the design and operating characteristics
of the facility may be enough for an expert to conclude that a release has
occurred.
Section 3008(h) orders (and civil suits) may be used to address releases
not only to the ground water, but to other media as well. The draft §3008(h)
guidance states that the authority covers releases of hazardous wastes into
4-16
-------
surface water, air, the land surface, and the sub-surface strata. The term
"hazardous waste" is not limited to those wastes listed or identified in
40 CFR Part 261. For §3008(h) purposes, the term hazardous waste also
includes the hazardous constituents identified in Appendix VIII of Part 261.
4.1.3 Formal Administrative Proceedings
Orders issued and penalties assessed under §3008(a) are subject to
formal administrative proceedings. Section 3008(a) proceedings are governed
by 40 CFR Part 22. (See Appendix B for a diagram of the process). The
Agency has not yet established the proceedings to be followed when issuing
§3008(h) orders.
Part 22, which governs the issuance of §3008(a) orders, sets out a
process that affords a respondent the opportunity to request a hearing on
the violation, the penalty, and the remedy proposed by the Agency. Following
any such hearing, the Administrative Law Judge will issue an Initial Decision
that includes a proposed Final Order and may include a proposed penalty. At
that point the respondent has 20 days in which to appeal the Initial Decision
to the Administrator. If an appeal is not made within this time period the
order becomes final and non-appealable 45 days after issuance of the Initial
Decision.
Section 3013 orders are not subject to any formal administrative
proceedings.
4-17
-------
4.2 Selection Among Order Authorities
There are a number of factors that should be considered when deciding
which order authority(ies) to invoke. The enforcement staff should consider
first which order authorities are applicable to the actions, inactions, or
conditions involved. Next, the Region should consider which of the applicable
authorities provide a legal basis for requiring the remedy that the Region is
seeking, including the assessment of penalties. Figure 4.1 may be consulted
for a general listing of the activities that can be sought under each authority.
In most cases, there will be several options that meet the tests of
applicability and coverage of the desired remedy. The enforcement options
can be further narrowed by considering: I) the strength of the evidence in
support of each type of order; 2) the elements that must be established and
whether they refer to regulations or must be established de novo; 3) the
amount of time that is likely to pass before compliance is achieved; and 4)
any complications that might arise from using certain combinations of
authorities.
When estimating the amount of time that may pass before compliance
with a §3008(a) order is achieved, the Regions should assess the probability
of the facility appealing the order. This is particularly important where
action needs to be taken quickly in order to halt or avoid a hazard or
endangerment. If the facility is likely to challenge a §3008(a) order
in the District Court, the Agency might elect to file a civil suit seeking
preliminary injunctive relief or to issue a §3013 order (if the §3013 test
could be met). Alternatively, the Agency could take action itself to
4-18
-------
mitigate an immediate threat to public health or the environment under
CERCLA §104.
When contemplating using two authorities to compel different aspects of
the desired remedy, enforcement officials should keep in mind the different
procedures that accompany each order. For instance, there may be cases in
which a Region would consider issuing simultaneous §3008(a) and §3013 orders:
a §3008(a) order to compel proper well placement and assess penalties and a
§3013 order to compel sampling for constituents not listed in Parts 260-270.
While simultaneous issuance of these orders is acceptable, the Region should
be aware that one order is subject to administrative hearings and the other
is not; therefore, appeal of the §3008(a) order may delay the full implemen-
tation of the remedy.
In general, a §3008(a) order enforcing Parts 265 and 270 and assessing
penalties will be the most practical enforcement option. Such an order can
be used to attain nearly any desired improvement to a ground-water monitoring
program. It can also be used, as noted in Section 1.2.1, to require a facility
to sample the ground water for constituents listed in Appendix VIII of Part 261.
Section 3013 and §3008(h) orders also have several common features that
make them particularly attractive in certain circumstances. Both order
authorities may be used to address contamination of media other than ground
water. For example, either order could be used to address facilities with
both ground-water and air problems. Moreover, unlike §3008(a) orders,
§3008(h) and §3013 orders are not bound by the ground-water monitoring regimen
specified in the regulations. Therefore, the Agency has more flexibility in
4-19
-------
specifying monitoring parameters and sampling frequencies when issuing §3013
and §3008(h) orders.
Each order authority also has unique features that may make it particu-
larly appropriate for certain situations. Section 3013, for example, grants
the Agency the authority to perform investigatory activities and recover
costs later if a respondent is incapable of or refuses to perform the neces-
sary actions. Section 3008(h) does not provide for cost recovery, but can
be used to compel facilities to go beyond the investigation stage and take
corrective action if necessary. In addition, §3008(h) orders can be used
to address past releases from solid waste management units and contamination
extending beyond the facility boundary.
4-20
-------
CHAPTER 5
FASHIONING A REMEDY AND DEVELOPING THE ENFORCEMENT STRATEGY
The first and perhaps most important step in developing an enforcement
action for a facility with ground-water monitoring problems is fashioning an
appropriate remedy. Only after outlining the desired remedy can the Region
design an enforcement strategy that will best achieve the desired results.
This chapter will describe several scenarios involving problem monitoring
programs and, using one common scenario as an example, will illustrate some
of the principles that enforcement officials should consider when designing
technical remedies. Then, using the same violator as an example, the chapter
will design an enforcement strategy to compel the model remedy.
5.1 Types of Violators
Each ground-water case will, of course, have unique features. It is
possible, however, to group RCRA ground-water violators into several broad
categories that characterize the status of the facility at the time of enforce-
ment review. Figure 5.1 outlines one possible scheme that divides facilities
into groups based on a combined evaluation of their Part 265 system and the
adequacy of their permit application. This scenario will be used later in
Figure 5.3 to illustrate possible remedies and enforcement strategies for
facilities with different types of ground-water violations.
The assumption in this scheme is that all the facilities listed are in
violation of Part 270 because they did not generate the information necessary
for permitting. In some cases, this deficiency derives from inadequate
5-1
-------
compliance, with Part 265 (facilities that have inadequate 265 detection
systems, for example, will not have generated the information necessary to
determine whether the facility should be permitted under detection monitoring,
compliance monitoring, or corrective action). In other cases, facilities
may have complied with 265, but not have completed all activities required by
the permit application regulations (e.g., the facility performed some assessment
activities based on Appendix VII, but did not sample for Appendix VIII as
required by §270.14(c)(4)).
FIGURE 5.1
Violator Classification Scheme
Scenario
Facility Status
Possible Sources of Inadequacy
1. No statistically significant change
in Part 265 indicator parameters;
Physically adequate detection network;
Agency has reason to believe there
Is contamination.
Part 265 indicator parameters are no
adequate to detect type of leachate
expected from facility; site hydro-
geology or facility's engineering
design puts facility at high risk
of leaking.
No statistically significant change
in Part 265 indicator parameters;
Inadequate Part 265 detection
system.
Well placements made based on insuf-
ficient hydrogeologic assessment;
Too few wells; Inappropriate sampling
device; Wells not properly developed,
etc.
Statistically significant change in
Part 265 indicator parameters;
Inadequate Part 265 detection system;
Inadequate Part 265 assessment.
Owner/operator used only indirect
techniques to assess plume.
Statistically significant change in
Part 265 indicator parameters;
Adequate Part 265 assessment;
Inadequate permit application.
5-2
Owner failed to identify all Appendix
VIII constituents in ground water;
Owner based concentration limits
on insufficient background sampling;
Owner failed to submit a feasibility
plan for corrective action, etc.
-------
5.2 Profile of a "Transition-Period" Violator
During the transition period between interim status and permitting, the
Agency envisions encountering a considerable number of facilities of the type
described in Scenario 2 (Figure 5.1). The Agency's experience to date has
indicated that in certain cases, owner/operators have installed monitoring
networks based on only a limited understanding of the hydrogeology underlying
their site. Monitoring wells have been located based on an evaluation of
local topography and, to the extent possible, evaluation of existing building
foundation borings. A considerable number of owner/operators have not performed
the type of detailed hydrogeologic site assessment the Agency considers
essential for the design of any ground-water monitoring system. Even fewer
have kept the type of well construction and design records the Agency needs
to evaluate the adequacy of the physical well network already in place.
As a result, EPA expects to encounter owner/operators who consider
themselves in compliance but who can not provide the background information
and documentation minimally necessary to substantiate the adequacy of
their Part 265 detection system. Without such information, the Agency will
not be able to decide whether a facility's detection system is or is not
capable of detecting contamination and hence whether the facility should be
permitted under detection monitoring, compliance monitoring or corrective
action. Not having detected a change in indicator parameters, however,
the facility most likely will have applied for a detection monitoring permit,
considering itself exempt from the assessment requirements of §270.14(c)(4).
5-3
-------
A typical "transition" facility, therefore, could be characterized as
follows:
o the facility has failed to adequately characterize the hydro-
geology underlying its site;
o therefore, the facility's well placements are inaccurate;
o the facility has sampled for the Part 265 indicator parameters.
No statistically significant increases have been detected in
existing downgradient wells;
o the facility's Part B is due. The facility has submitted a
summary of its interim status monitoring data and has proposed
an expanded list of indicator parameters for Part 264 monitoring.
The permit application includes procedures for establishing back-
ground values for these parameters, but does not include actual
background values based on pre-permit sampling.
This chapter will use the above scenario to illustrate some of the
principles enforcement officials should consider when designing remedies for
facilities during the interim status to permitting transition period. The
chapter uses Scenario 2 as its point of departure because a facility that
has not detected contamination under interim status presents the greatest
challenge to enforcement officials. Moreover, the remedies appropriate for
the other scenarios presented in Figure 5.1 are but a variation of the remedy
outlined in the following section for the facility described in Scenario 2.
Table 5.5 at the end of the chapter summarizes the variations on the
remedy appropriate for each of the other listed scenarios.
5.3 Outline of the Remedy
When faced with a facility that has a technically inadequate detection
monitoring system, enforcement and permitting officials must consider first
5-4
-------
what makes sense for a facility to do in light of the facility's past and
future monitoring obligations. By this point in the program, an interim
status facility should have installed a fully competent detection monitoring
system, determined with confidence whether there was a statistically signifi-
cant indication of ground-water contamination, and fully characterized any
plume for both Appendix VII and VIII constituents (if contamination were
detected). If a facility has not successfully completed even the first
step - the installation of a competent detection system - it cannot be
allowed to begin the entire sequence anew. Proceeding from the beginning
would mean upgrading the detection system and sampling for one year to
establish background before even the first determination of contamination
is made.
As the time line in Figure 5.2 points out, proceeding through this
entire sequence could take up to two and one-half years. This approach
would lead to unacceptable delays in the permitting process and would
penalize those facilities who had complied with the program all along.
In effect, "starting over" would merely allow facilities that had avoided
the costs of complying in the past, to delay the costs of full compliance
for an additional period of time.
Instead, such facilities should be required to make an accelerated
determination of whether or not contamination has occurred. This determina-
tion can then be used to decide what additional actions, if any, the applicant
must perform to meet his/her permit application requirements.
5-5
-------
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Before a determination of leakage can be made, the facility must install
a monitoring network capable of detecting contamination. In general, this will
require such facilities to perform additional site characterization and then,
based on the results, expand or replace their existing monitoring network.
Once a competent detection network is in place, the facility is in a position
to determine whether or not contamination has occurred.
The Agency suggests that the determination of whether contamination has
occurred be made based on a comparison of upgradient and downgradient values
obtained for an expanded list of indicator parameters. The indicator para-
meters should be selected based on the specifics of the site and should
include constituents that would be expected to be at the leading edge of any
plume of contamination (see Section 5.4.2). The comparison should be based
on the mean of pooled data obtained through accelerated sampling over a short
period of time. The plan for this determination should be designed to con-
clusively confirm or refute contamination in the shortest period of time
possible.
If contamination has occurred, the facility owner must proceed to charac-
terize the plume and, based on the results, apply for either an operating or
post-closure permit that includes compliance monitoring and/or corrective
action. If contamination has not occurred (i.e. the results of interim
status monitoring were correct even though the detection system was not fully
competent), then the facilty would apply for a permit as a detection monitoring
facility.
5-7
-------
Thus the preferred technical response for a facility that has not triggered
under detection monitoring but has an inadequate Part 265 detection system is
as follows:
1) Conduct a detailed assessment of the site's
hydrogeology (fill in gaps in the facility's
current understanding of the site's subsurface).
2) Install a monitoring network (or modify/expand
an existing system) to meet the objectives of Parts
265/264 detection monitoring.
3) Sample for an expanded list of indicator parameters.
4) Determine whether contamination has occurred based
on a comparison of upgradient and downgradient well
samples obtained over a short period of time
(accelerated sampling).
5) If contamination is confirmed, begin characterizing
the plume based on monitoring of Appendix VIII
constituents.
6) Sample to establish background for all Appendix VIII
constituents detected in ground water.
7) If downgradient Appendix VIII values are significantly
greater than background values, have facility develop
corrective action plan and apply for corrective action
permit.10
If downgradient Appendix VIII values are lower than back-
ground, have facility submit a corrective action feasibility
studyI* and apply for a compliance monitoring permit.
10 Note that if the permit is not likely to be issued quickly, the Agency
may wish to initiate corrective action while the facility is still in interim
status. Several authorities are available to compel such corrective action,
including §3008(h), §7003 and Section 106 of CERCLA. Further, in some
instances, the Agency may choose to conduct a response action under the
authority of CERCLA §104.
11 Section 270.l4(c)(7) requires applicants to submit a corrective action
feasibility study when applying for a compliance monitoring permit. The study
must include sufficient information to predict what type of corrective action
(e.g., trench recovery, pumping and treatment) would be appropriate if reme-
dial work proved necessary at that site. It is not meant to be a fully
developed plan for corrective action; such a plan must be developed pursuant
to §264.99(i)(2) if the facility ever exceeds its ground-water protection
standard.
5-8
-------
The schedule of achieving the above remedy will of course depend on the
particulars of the site involved, especially the complexity of the site's hydro-
geology. While it is impossible to predict how long it will take (or should
take) to accomplish each step, the sequence of monitoring events in this remedy
should be significantly shorter than the sequence laid out in the regulations.
As illustrated in Figure 5.3, the remedy recommended in this document
in effect eliminates the collection of a year's worth of background data and
condenses the monitoring required by Part 265 assessment [primarily Appendix
VII] and §270.I4(c)(4) [Appendix VIII] into one plume characterization phase.
Now confirmation (or denial) of leakage can be accomplished through accelerated
sampling over a period of weeks or months rather than taking over a year.
5.4 Discussion of the Remedy
The basic elements of the remedy are the design and installation of a
competent detection monitoring well network; determination of whether or not
leakage has occurred based on sampling for an expanded list of parameters;
and the fulfillment of all applicable Part 270 informational requirements.
The following section will describe briefly certain factors enforcement
officials should keep in mind when developing each aspect of the remedy.
Later sections will explore the order and regulatory authorities available
to compel each of the outlined activities.
5.4.1 Design and Installation of a Competent Monitoring Network
The facility owner should be required to upgrade his/her existing network
to meet the detection standards of Part 265. The reader should note that if
5-9
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an owner/operator's hydrogeologic data submitted pursuant to §270.l4(c)(2) is
inadequate, it is likely that the facility's detection monitoring well network
ts inadequate as well. The reader should also note that since the the design
and construction standards for a Part 265 system are essentially the same as
those required by Part 264 (see Chapter 3), the network installed for the
determination of leakage proposed in the model remedy should serve equally
well as the facility's Part 264 detection monitoring system if no plume is
found.
5.4.2 Confirmation of Leakage Based on Expanded Sampling
Central to the determination of leakage proposed in the model remedy is
the development of a list of meaningful indicator parameters. When selecting
parameters, enforcement officials should not limit themselves to the four
indicators listed in §265.90.12 These parameters were selected as the best
indicators available to detect a broad spectrum of possible leachates.
Because the interim status regulations were meant to be self-implementing,
Part 265 detection monitoring could not rely on waste-specific indicators
selected for each facility. As a result these parameters are limited in
their ability to indicate contamination soon after leakage.
The Part 265 indicator parameters are limited in three ways. First,
the Part 265 indicator parameters are subject to sources of natural variation
that can mask the presence of low levels of contamination. There are many
natural sources of variation in pH, for example, that could obscure changes
*2 See Section 5.5.2 for an explanation of the authorities available
to compel sampling for a broader list of parameters.
5-11
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in this parameter caused by leachate. Changes in levels of a specific para-
meter such as benzene, however, are not generally subject to such background
"noise." Second, with the exception of TOX (which can be detected at below
20 ppb), the lower detection limit of the other parameters is not sufficiently
sensitive to register some changes in water chemistry that may represent
leakage. Finally, because the Part 265 indicator parameters are surrogate
measures, increases in a particular chemical constituent do not necessarily
cause an equivalent change in an indicator parameter. A 5 mg/1 change in
lead, for example, would only initiate a very small change in specific con-
ductance (if any). The same increase in concentration would initiate a
significant change, however, if the facility were sampling for lead itself.
Therefore, enforcement officials should select indicator parameters that
are based on the chemical composition of the facility's waste. The enforcement
official should have the facility identify both the hazardous and non-hazardous
constituents of the facility's waste, including any constituents likely to
form as a result of chemical reactions occurring in the facility or in the
leachate as it migrates through the subsurface. Then the owner/operator
should identify those constituents that can be considered the most mobile and
persistent in the unsaturated and saturated zones beneath the facility. The
enforcement official should then select those parameters that individually
or as a group (e.g. TOX) can provide the most reliable indication of leakage.
Special attention should be given to whether the parameter is easily detected
in water and to the variability of the parameter in background water. If
background concentrations of a potential indicator parameter are sufficiently
high or exhibit a high degree of variability, the arrival of low or moderate
concentrations of leachate may be masked.
5-12
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The list of parameters finally selected should be representative of
constituents at least as mobile as the most mobile hazardous constituent
reasonably expected to be derived from the facility's waste. Concentrating
on the most mobile constituents will ensure that the arrival of leachate is
detected at the earliest possible time.
In addition to indicator parameters, enforcement officials should consider
having the facility sample for additional parameters that characterize the
general quality of water at the site (e.g., Cl~, Fe, Mn, Na+, SO^, Ca+, Mg+,
+ —3 =
K , NO , PO^ , silicate, ammonium, alkalinity or acidity). Baseline data on
the inorganic chemical composition of ground water can provide an important
basis for comparison and planning should the program enter the assessment
phase. Information on the major anions and cations that make up the bulk of
dissolved solids in water, for example, can be used to determine reactivity
and solubility of hazardous constituents and therefore predict their mobility
under actual site conditions.
5.4.3 Fulfillment of Applicable Part 270 Requirements
When designing the remedy, enforcement officials should include elements
that address the facility's information obligations pursuant to Part 270. If
contamination is confirmed, the facility must generate the remainder of the
information required by §270.14(c)(4), namely the extent of migration of any
plume and the concentration of all Part 261 Appendix VIII constituents present
in the plume.
Enforcement officials should also ensure that the remedy includes the
collection of background data on all Appendix VIII constituents detected in
5-13
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ground water. For many constituents, these data will be necessary to
establish concentration limits for incorporation into the facilty's ground-
water protection standard. As described in section 3.2.1, the permit writer
will have to set concentration limits based on the mean of pooled data avail-
able at the time of permitting (unless there is a high temporal correlation
between contaminant concentrations in upgradient and downgradient wells in
which case concentration limits may be established through sampling at the
compliance point). Therefore, it is in the best interests of both the
facility and the Agency to have sufficient data available at the time of
permitting to accurately characterize the quality of the background water
at the site.
To guarantee sufficient data, enforcement officials should consider
incorporating in the facility's prescribed remedy an accelerated program of
background sampling for Appendix VIII constituents. The frequency of sampling
should be dictated by the needs of the statistical test proposed by the facility
for use in compliance monitoring. The sampling schedule should also consider
the need for establishing seasonal and spatial variation in contaminant levels
if such variation is expected at the site. Sections 6.3 and 7.3.2 of the
Permit Writer's Guidance Manual provide further guidance on these points.
In addition, the order should require the submittal of the various
plans and feasibilty studies necessary to establish a compliance monitoring
program or a program for corrective action pursuant to §§270.l4(c)(7) or (8)
(see Section 2.3.2). By placing these permit application requirements on an
enforceable compliance schedule, enforcement officials can help ensure that
the requirements will be fulfilled in a timely manner.
5-14
i
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5.5 Application of Enforcement Authorities to the Remedy
Once the enforcement staff and permit writer devise an appropriate remedy,
the enforcement staff must determine the order and regulatory authorities best
suited to compel the desired actions. As Section 4.2 on selecting order author-
ities points out, there are a variety of factors enforcement officials must
consider when developing an enforcement strategy.
When deciding between order authorities, officials must first establish
the applicability of the order to the situation at hand (i.e., does the
situation meet the conditions necessary for the issuance of a particular
order). Next, the official must consider whether the order can compel all
aspects of the desired remedy. Where possible, it is advantageous to secure
the entire remedy through a single authority in order to save resources and
avoid the possibility of different appeal procedures. Finally, enforcement
officials must factor in other relevant concerns such as the facility's
compliance history and whether or not it is important in the instant case to
assess a penalty. In certain circumstances, features such as the ability to
assess a penalty may become the deciding factor when choosing between order
authorities.
This section will apply the above principles to the model remedy
developed in this chapter. It will outline a preferred enforcement strategy
for the model remedy and will note where changes in the remedy could suggest
needed changes in the proposed strategy. Table 5.5 at the end of the chapter,
summarizes various enforcement strategies for facilities with different
ground-water violations and different technical remedies.
5-15
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5.5.1 Selection of the Order Authority
Assume that the only information known about the Scenario 2 facility is
that presented in Figure 5.1; namely, the facility is in violation of the
Part 265 ground-water regulations for the following reasons:
1. the facility located its wells based on a poor understanding of the
site's hydrogeology;
2. there are too few wells installed; and
3. the owner cannot demonstrate that existing wells were properly
constructed.
In addition, the facility is in violation of §270.14(c)(4) because the owner
made no attempt to look for and assess any plume beneath the facility before
the facility's Part B due date passed.
Based on the above information alone, the most appropriate order author-
ity for compelling the model remedy of this chapter would be a §3008(a) order
enforcing Parts 265 and 270. A §3008(a) order is the authority of choice
for three reasons. First, the condition for issuing a §3008(a) order has
already been met - the facility is clearly in violation of the regulations.
To use either of the other authorities, the Agency may have to expend addi-
tional resources to collect evidence that there may be a substantial hazard
to public health or the environment [§3013] or a release of hazardous waste
or constituents into the environment [§3008(h)].
Second, as the following section will explain, the entire remedy can be
compelled using a §3008(a) order citing relevant sections of Parts 265 and
270. The remedy as presently conceived focuses exclusively on evaluating
5-16
-------
the impact of the facility on ground water; hence, an order that can address
other media, such as a 3013 or 3008(h) order, is not needed. Further, in
this particular case, there is no reason to suspect that the threat posed by
potential ground-water contamination is so compelling as to require corrective
action prior to permitting. Therefore, it is not essential to use an order
that can accommodate clean up of ground water during interim status. Of
course, if additional evidence collected during plume characterization
indicated that clean up should be pursued immediately, a §3008(h) order could
be issued subsequent to the initial §3008(a) action.
Finally, a §3008(a) order has the added advantage that it can be used to
assess penalties. Given that the facility has been out of compliance for the
entire history of the program, the Agency should exercise its authority to
assess penalties for past and continuing violations including the recovery of
the facility's economic benefit of non-compliance.
Of course, if the starting scenario were different, the considerations
guiding the selection of an order authority could change significantly. For
example, if there were evidence of off-site contamination (e.g., a fish kill
in a nearby stream) and the facility were known to delay resolution of pro-
ceedings by exercising every opportunity for appeal, enforcement officials
may decide to postpone the assessment of penalties and immediately issue an
order under §3013, §7003 or CERCLA §106 to avoid the time delay afforded by
the administrative process. In another case, if a facility were out of
compliance with the ground-water regulations and had significant soil contami-
nation, the Region could use a §3008(h) order to achieve both compliance with
5-17
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the regulations and clean-up of contaminated soil. The proper way to balance
the advantages and disadvantages of each order authority can only be determined
in the context of a particular situation.
5.5.2 Securing the Model Remedy Through a §3008(a) Order
As outlined in Figure 5.4, the model remedy derives directly from the
regulations. Sections from Part 265 and 270 may be cited to compel
additional hydrogeologic investigation and the installation of an adequate
well network. Section 270.14(c)(4) may be cited to force sampling for an
expanded list of parameters and to justify the comparison of upgradient and
downgradient wells based on accelerated sampling. Finally, relevant sections
of the Part 270 regulations may be cited to require the collection of back-
ground data on Appendix VIII constituents and the submission of other plans
and data necessary for permitting.
Figure 5.4
MODEL REMEDY
1. Fill in gaps in the current understanding
of the site's hydrogeology
2. Install a monitoring network (or expand an existing
system) to meet the objectives of a Part 265/264
detection system
3. Sample for an expanded list of indicator parameters:
Part 265 indicator parameters (TOX, TOC, pH, specific
conductance)
REGULATORY CITES
§265.90(a)
§265.91
§270.14(c)(2)
§265.91
§265.92(b)(3)
5-18
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Figure 5.4 (continued)
Part 265 water quality parameters (Cl, Fe, Mn, Na,
Phenols, Sulfate)
Substances with National Interim Drinking Water
Standards (Appendix III, Part 265)
Appendix VIII of Part 261
4. Determine whether contamination has occurred
based on a comparison of data collected from
up- and downgradient wells over a short period
of time.
5. If contamination is confirmed, begin assessing the
plume based on monitoring of Appendix VIII constituents
6. Sample to establish background for all Appendix VIII
constituents detected in ground water
7. Submit data and plans required for either
compliance monitoring or corrective action
§265.92(b)(2)
§265.92(b)(L)
§270.14(c)(4)
§270.14(c)(4)
§270.l4(c)(4)
§270.14(c)(7)(iv)
§270.14(c)(7) or
(8)
The regulatory cites in this strategy are relatively straight forward;
however, the role of §270.14(c)(4) deserves attention. As section 2.3.1
explains, the Agency may require a facility to look for and assess a plume
at any facility where the owner/operator's program of interim status monitor
ing has detected a plume or has failed to establish definitively whether or
not a plume exists.
Under §270.I4(c)(4), the facility is obligated to assess the extent of
any plume and sample for the full complement of Appendix VIII constituents.
5-19
-------
Therefore, It is within the Agency's authority to require the facility to
begin assessment and full Appendix VIII sampling immediately. The model
technical remedy, however, limits the scope of sampling to a more manageable
list of indicator parameters until the presence of a plume is confirmed or
refuted. In effect, the model technical remedy refrains from immediately
exercising the full power of §270.14(c)(4) in order to avoid wasted effort if
indeed the facility has not leaked.
5.6 Variations on the Model Scenario
This chapter has used the facility described in scenario 2 to illustrate
some of the principles enforcement officials should consider when designing
technical remedies and developing enforcement strategies. As the scenario
changes, the remedy appropriate for the situation and the enforcement tools
available to secure that remedy change as well. Figure 5.5 (at the end of
the chapter) illustrates how the technical remedy and enforcement response
vary based on the status of the facility at the time of enforcement review.
It is important to note that all proposed remedies include correcting any
deficiencies in the existing detection network even if the facility has already
detected contamination and begun to characterize the plume. As described in
the Chapter 2, a sound well network at the limit of the waste management area
is critical to every phase of ground-water monitoring, from interim status
monitoring to compliance and/or corrective action monitoring. Therefore, it
makes sense to correct any deficiencies in the interim status detection
system, because these wells will be used throughout the life of the facility.
Moreover, a system may have detected a plume in one area and still be incapable
5-20
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of detecting a plume at some other point. In such cases, the system should
be upgraded so that it will be capable of detecting future plumes of contam-
ination.
It is further important to note that where a facility has managed to
detect a statistically significant change in indicator parameters even
though its detection system is inadequate (see Scenario 2 in Figure 5.5),
enforcement officials should require the facility to begin characterizing
the plume downgradient from the triggering well and at the same time perform
additional hydrogeologic evaluation and upgrade the detection network.
Finally, the technical remedies outlined in this chapter are appropriate
not only for operating units but also for most units that are closed or are
planning to close. Section 270.l(c) states that units closing after January
26, 1983 must have permits during the post-closure period.13 por units
that accepted hazardous waste after July 26, 1982, the post-closure permit
would include the ground-water monitoring program set out in Part 264 and
the permit application would include the ground-water monitoring data required
under §270.14(c). Thus, once a closing unit's Part B application is due,
enforcement officials can rely on the same range of enforcement options that
are available to address operating units.
13 in order to implement §3005(i) of the Solid Waste Disposal Act, as amended,
the Agency intends to propose amending §270.l(c) to make all units closing
after July 26, 1982 subject to post-closure permits. Section 3005(i) of the
revised Act makes all units receiving wastes after 7/26/82 subject to Part
264 ground-water monitoring and corrective action requirements. Since a permit
is the means by which the Agency implements the Part 264 standards, the
Agency considers it necessary to revise §270.l(c) in order to make all units
subject to Part 264 ground-water monitoring and corrective action also subject
to post closure permitting.
5-21
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There are three categories of units that would not currently be subject
to the Part 265/270 program outlined in this chapter. First, units that
closed before January 26, 1983 are not required to obtain permits and thus
are not subject to Part 270 requirements [codification rule may roll this
date back to July 26, 1982]. Second, units that ceased receiving hazardous
waste by July 26, 1982 are not subject to the Part 264 ground-water monitoring
provisions and therefore, in applying for the permit, would not need to
include the ground-water data required under §270.14(c)(4). Third, no post-
closure requirements apply, and thus no permit or permit application is
currently required for a surface impoundment or waste pile that closes by
removing all hazardous waste and waste residues from the unit, the under-
lying and surrounding soil, and the ground water. The Agency is presently
evaluating whether §3005(i) may require the Agency to make units that clean
closed under Part 265 but received waste after 7/26/82 subject to post-closure
permitting in order to implement Part 264 ground-water monitoring and corrective
action.
In all of the above cases, however, the Part 265 ground-water monitoring
requirements do apply and should be enforced.1^ In the case of a surface
impoundment closing through removal, the Agency/State should ensure that the
14 The successful execution of closure responsibilities (e.g., installation of
a cap, run-off and run-on control) does not absolve a facility from its Part 265
ground-water monitoring responsibilities. Section 265.117 of the regulations
states that closed facilities must comply with the ground-water monitoring and
reporting requirements of Subpart F for 30 years after the date of closure.
Therefore to meet its post-closure care requirements, a closed or closing
facility with an inadequate Part 265 monitoring network would have to upgrade
its system and assess any plume of contamination detected during the post-closure
care period.
5-22
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closure plan provides for monitoring that is adequate to demonstrate the
absence of hazardous waste in the ground water. Surface impoundments
generally cannot qualify for closure by removal if any hazardous waste is
present in the ground water; such impoundments must instead close as land
disposal facilities.
5-23
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CHAPTER 6
DEVELOPING ORDERS
The purpose of this chapter is to help enforcement officials ensure that
the ground-water remedy sought by the Agency is in fact executed by the respon-
dent. The chapter will discuss the importance of specificity in detailing
the desired remedy and various strategies that may be followed in developing
and issuing orders. The chapter will concentrate exclusively on how to
develop the technical content of compliance orders; it will not address
legal issues related to writing orders or issuing complaints. Guidance on
such issues is already available in the Compliance/Enforcement Guidance
Manual dated September, 1984 (See especially Chapter 7, "Administrative
Actions: Civil").
6.1 Import .mce of Specificity
The Agency's experience to date suggests that certain members of the
regulated community have failed to implement a ground-water system capable
of meeting the requirements of Parts 265 and 270. This is particularly
true with respect to Part 265's broad performance standards and may increase
with respect to Part 270 as Part B applications are filed. As Section
4.1.2 points out, even though the regulations do not specify in detail how a
system should be designed and operated, the performance language demands a
rigorous program of hydrogeologic investigation, network design, well
construction, and sampling and analysis.
6-1
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Despite the high standards set by the regulations, certain owner/
operators have ignored this performance language and have installed only
four wells (three downgradient and one upgradient), in settings whose complex
hydrogeology require a substantially greater number of wells.
In light of the failure of certain facilities to achieve the high standards
set by the regulations, it is essential that the Agency introduce specificity
into the administrative enforcement process. In the course of each administra-
tive proceeding there must develop between the Agency and the respondent an
express understanding as to what activities will constitute compliance with
the regulations. Administative orders that are explicit regarding the Agency's
expectations can help ensure that the actions taken by the owner/operator
will be sufficient to bring the facility into compliance. Specificity regard-
ing what will be considered appropriate or adequate, can help avoid the
wasted time and effort that results when a respondent performs actions later
deemed inadequate. It is clearly in the best interest of both parties to
ensure that the facility's first effort to come into compliance meets the
Agency's requirements.
The Agency can secure this assurance either by reviewing the owner/
operator's plans for coming into compliance before the work is actually
performed or by specifying up front exactly what actions are required of the
respondent. An order, therefore, can be structured in one of two ways. If
issued prospectively, an order may be structured around the submittal, and
subsequent Agency review, of individual plans outlining the respondent's
proposed actions for implementing each phase (hereafter referred to as a
6-2
f
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"phased order"). Alternately, the Agency can issue highly explicit orders
that define technically what the owner/operator must do to come into compli-
ance.
The next two sections of this document explain the above two types of
order in greater detail. Both orders place the burden of system design on
the respondent, yet provide the Agency with an opportunity to veto any design
before the system is actually implemented. When issuing either type of order,
enforcement officials must make clear that notwithstanding compliance with the
order, the respondent remains responsible for compliance and abatement of
any ground-water contamination A specific provision should be included in
all orders noting that the respondent may be required to take further actions
as necessary to comply with RCRA or other applicable laws.
6.2 Phased Orders for Ground-Water Monitoring Violations
The concept of phased orders is relatively new to the RCRA program. As
its name implies, a phased order lays out a series of actions the respondent
must take over time in order to come into compliance. Each action or phase
is linked to an enforceable compliance schedule and generally includes some
mandatory interaction between the respondent and the Agency. Most commonly,
each phase will include the development of a plan by the respondent to accom-
plish a specified goal; the submittal of the plan to the Agency for review,
modification, or approval; and the eventual execution of the plan by the
facility owner.
A phased order format is especially well suited for addressing ground-
water monitoring violations at hazardous waste facilities. In many ground-
6-3
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water cases, the nature of the violation is such that neither the facility
nor the Agency knows at the outset exactly what actions will be necessary
and sufficient to bring a facility into compliance. Many ground-water viola-
tions, for example, derive directly from a facility's lack of understanding
of the hydrogeology beneath their site. As more information is collected
and interpreted, the steps appropriate for a respondent to take may change.
Developing a technical remedy under such circumstances is, of necessity, a
dynamic process.
A phased order, however, can accomodate these changes. By proceeding
in stages, a phased order allows the Agency to structure and guide a facility's
actions without locking the facility or the Agency into a specific remedy
that may prove inadequate. Moreover, the order provides a mechanism for the
Agency to communicate more specifLcally EPA's expectations regarding various
aspects of the owner/operator's response. For example, the Agency can set
out in the order the information a hydrogeologic assessment must yield in
order to provide the level of detailed understanding the Agency considers
necessary for the installation of an adequate ground-water monitoring system.
Where the Agency has specific preferences on how certain types of information
should be obtained (e.g., a preference for specific tests or procedures),
enforcement officials can specify the use of the test in the order. Alter-
nately, an order may list objectives or considerations that an owner/operator
must incorporate into his/her decision-making. The order might specify, for
example, that the owner/operator must demonstrate in the plan that a pro-
posed sampling device: 1) minimizes the potential for degassing; and
2) minimizes the potential for adsorption and desorption of constituents.
6-4
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Appendix A includes a sample order that illustrates some of the above
options. This order is structured around the needs of the "transition
facility" described in Chapter 5; recall that this facility has an inadequate
detection monitoring system and has not detected a significant change in the
Part 265 indicator parameters. The preferred technical and enforcement
response for such a facility is summarized below.
Action on the Part of Facility Owner
Enforcement Authority
1) Conduct detailed assessment of site's hydrogeology
(fill in gaps in current understanding of site's
subsurface).
2) Install a monitoring network ( modify/expand an existing
system) to meet the objectives of 265/264 detection.
3) Sample for an expanded list of indicator parameters.
4) Determine whether contamination has occurred by
comparing upgradient and downgradient well samples
collected on an accelerated schedule.
5) If contamination is confirmed, begin characterizing
the plume based on monitoring of Appendix VIII constituents.
1. §265.91(a)
§270.14(c)(2)
2. §265.91
3. §270.14(c)(4)
To implement this remedy, the sample order in Appendix A mandates the
execution of six tasks:
1) Submittal of a plan to conduct a hydrogeologic assessment of the
site;
2) Submittal of a list of constituents or parameters to be monitored
for (Note: sampling protocol and well construction materials will
be dictated by chosen indicator parameters);
3) Submittal of proposed monitoring network, including well locations,
screening depths, construction methods, and design specifications
(e.g., filter pack material, slot size, well diameter);
6-5
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4) Submittal of a sampling and analysis plan;
5) Execution of the plans developed in steps 1, 3, and 4 (following
Agency approval);
6) If contamination is confirmed, submittal of a plan outlining
proposed assessment activities.
The order combines these tasks into three phases and establishes compliance
deadlines for each phase. For example, the order requires the owner/operator
to develop and submit the hydrogeologic assessment plan and the list of
parameters by the same date (phase 1). Next, the order instructs the respon-
dent to complete the assessment and submit the results of the investigation
along with a monitoring network plan and a sampling and analysis plan by the
next compliance date (phase 2). After EPA approves or modifies these plans,
the order requires the respondent to make the first determination of contami-
nation and submit the results and an assessment plan (if contaminatioa is
confirmed) by the final date (phase 3).
The sample order combines the required tasks in the above manner for the
purpose of illustration only. In every case, the logical sequence of events
will be dictated by the particulars of the site. Enforcement officials must
use professional judgement when deciding which tasks are appropriate, how they
should be combined, and what level of Agency/facility interaction the order
should mandate.
6.3 Technically Specific Orders
Rather than structure the development of the technical remedy through the
order itself, enforcement officials may prefer to oversee the collection of
background data and the development of a proposed remedy through informal
interaction and negotiations with the facility. This approach is acceptable
6-6
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as long as the work done in preparation of the remedy (e.g., hydrogeologic
assessment activities), and the final terms of the remedy itself (e.g., well
locations, sampling schedules), are set out in a technically-specific order
(usually on consent). The order may be issued before the wells are installed
and the sampling conducted, or it may be issued afterwards. If negotiations
become protracted and work is not proceeding expeditiously, however, the
Region should issue the order and place the facility on an enforceable
compliance schedule.
Whether the work is conducted before the order is issued or after, detail
in the order regarding completed and proposed work will help avoid future
questions of compliance with the order. The greater the specificity in the
order, the easier it will be for the Agency or a court to determine whether
the terms of the agreement have been met.
Enforcement officials should not underestimate the level of detail that
can be incorporated into orders. Well design specifications, decontamination
procedures, and sampling frequencies are all suitable for specification. In
addition, enforcement officials should consider specifying certain behaviors
or actions on the part of the respondent. For example, officials may wish
to require that a qualified geologist be present to take field notes (e.g.
drilling logs and boring logs) during all well installations and soil boring
programs.
No requirement is inappropriate if it is directly related to the ability
of the owner/operator to meet his regulatory obligations. Table 6.1 summarizes
some of the items enforcement officials may wish to consider when developing
orders.
6-7
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Table 6.1 Possible Elements of a Technically-Specific Order
HYDROGEOLOGIC ASSESSMENT
Boring Program
o Spacing of boreholes
o Depth and location of boreholes
o Vertical spacing of samples within each borehole
o Sampling equipment to be used for boring program
o Information to be logged for each borehole
o Requirement that hydrogeolegist or geotechnical engineer be present to
log boreholes
o Method for stabilizing selected boreholes until wells are installed
o Method of data presentation
o Requirement to use Unified Soil Classification System (USCS),
Atterberg limits
Water Level Monitoring Program
o Spacing/number of piezometers or wells
o Method for water level measurements
o Required precision of measurement (to the nearest 0.1 foot or to the
nearest centimeter)
o Requirement that measuring points be surveyed from established benchmarks
o Number of hydrogeologic cross sections and appropriate scale
o Water level contour maps
o Identification of local sources of ground-water withdrawal and recharge
and approximate schedule of use
Hydraulic Conductivities
o Method of determining hydraulic conductivities, porosity
Additional Information Requirements
o Description of regional geologic and hydrogeologic characteristics
o Analysis of geomorphic or topographic features that might influence
ground-water flow system
o Zones of higher or lower permeability that might direct or restrict
flow of contaminents
o Zones of significant fracturing or channeling in consolidated deposits
o Sand or gravel deposits in unconsolidated deposits
o Description of manmade hydraulic structures (pipelines, french drains,
ditches, etc.)
o Soil properties including cation exchange capacity, organic content
temperature profile, grain size distribution
6-8
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Additional Information (continued)
o Identification of zones of recharge and discharge
o Interpretation of hydraulic interconnections between saturated zones
NETWORK DESIGN
Placement of Wells
o Maximum horizontal spacings
o Requirement for well clusters
o Depth requirements (most in surficial aquifer, one or more in deeper
aquifer
o Exact well locations
o Minimum number of background wells
Well Design and Construction
o Casing material and diameter; prohibition against joining section with glues
or sealants
o Screen slot size and maximum length
o Drilling techniques; prohibition on use of drilling muds
o Drill decontamination procedures
o Well development techniques; prohibition on use of water other than formation
water or "certified" pure water
o Filter pack material and method of filter-pack emplacement
o Method and material for sealing annular space
o Requirement for locked well caps
o Requirement that wells be designed to last at least 30 years
o Requirement that wells yielding turbid samples be redeveloped or replaced
o Information to be documented during construction of each well
SAMPLING AND ANALYSIS
Analytes of Interest
o List of parameters to be monitored for
o Requirement to collect data on major ions and anions, e.g., Cl~", Fe, Mn,
Na , Ca+, Mg+, N03~, P0^=, silicate, ammonium, alkalinity, acidity.
o Requirement for field monitoring of pH, conductivity, and temperature for
each sample
Sample Collection
o Evacuation procedures; handling procedures for evacuation water
o Method for sampling "floaters" and "sinkers"
6-9
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Sample Collection (continued)
o Acceptable materials for inclusion in sampling devices and/or specific
device to be used
o Performance standard for sample collection - "sampling device and
methodology must be selected to yield representative samples in
light of the parameters that are being monitored"
o Requirement that sampling devices be dedicated to each well or procedures
for decontaminating equipment between wells
o Precautions on use of specific sampling devices (e.g., bladder pumps must
be operated in a continuous manner so that they do not produce pulsating
samples that are aerated in the return tube upon discharge; check valves
must be designed and inspected to ensure that fouling problems do not
reduce delivery capabilities or result in aeration of sample, etc.)
o Specification of acceptable cords/cables to be used to lower bailers;
prohibitions on use of braided cables, polyethylene or nylon cords
o Maximum sampling rates, generally not to exceed 100 milliliters/minute
SAMPLING PRESERVATION AND HANDLING
o Designation of appropriate sample containers - polyethylene containers
with polypropylene caps when metals are analytes of interest; glass
containers when organics are analytes of interest
o Requirement to use preservation methods designated in SW-846
o Preferred handling procedures e.g., volatile organics: no filtering
or headspace in containers allowed; metals: two aliquots from each
sample - one filtered and analyzed for dissolved metals, and one
not-filtered and analyzed for total recoverable metals
ANALYSIS
o Requirement for use of field blanks, standards, and spiked samples
for QA/QC
o Requirement to use analytical methods described in SW-846
o Requirement to perform field analysis of pH, conductivity, and
temperature
CHAIN OF CUSTODY
o Minimum requirements for chain-of-custody program (e.g., sample labels,
seals field log book, chain of custody record, sample analysis request
sheet, laboratory log book)
DATA REVIEW AND PRESENTATION
o Standard protocol for reporting of less than detection limit concentrations
o Requirement that data values for each pollutant be reported using the same
number of significant digits, in general at least three t
6-10
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DATA REVIEW AND PRESENTATION (continued)
o Requirement that units of measure for a given chemical parameter be
consistent throughout report and accompany each chemical named
o Requirement that raw data be submitted in a table that lists for each
concentration value: the pollutant, the well code, and the unit of
measure
o Requirement that owner/operator compile the following ten statistics for
each of four summary tables organized by pollutant; by pollutant-well; by
pollutant-date; and by pollutant-well-date:
0 Number of lower than detection limit values
0 Total number of values
0 Mean
0 Median
0 Variance
0 Standard Variation
0 Coefficient of variation
0 Range
0 Minimum value
0 Maximum value
ADDITIONAL PLUME CHARACTERIZATION ACTIVITIES
o Requirement to use certain remote sensing (e.g., aerial photography)
and geophysical techniques (e.g., electrical resistivity, ground-pene-
trating radar, borehole geophysics)
o Requirement to determine the physical and chemical characteristics of the
facility's leachate including density, solubility, vapor pressure,
viscosity, and octanol-water partition coefficient
PERMIT APPLICATION REQUIREMENTS
o Requirement to collect background data on all Appendix VIII constituents
detected in ground water
o Requirement to submit applicable data, studies, and plans detailed in
§270.14(c)(l) - (8)
OTHER PROVISIONS
o Schedule for implementation including stipulated penalties for missed milestones
o Penalties for past and present violations
o Procedures for plan submittal, modification, and/or approval
o Provision that incorporates all plans, reports, and schedules required by the
ORDER into the ORDER itself such that any non-compliance with a plan, report
or schedule consitutes non-compliance with the order
6-11
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OTHER PROVISIONS (continued)
o Clause that reserves government's right to take further action as necessary,
including additional ground-water monitoring and/or cleanup, to bring respondent
into compliance with RCRA other applicable State or Federal law
o Requirement to develop and implement a community relations plan
o Requirement to develop and implement a health and safety plan for workers
involved with monitoring or corrective action
o Requirement to designate corporate contact person, supply corporate
organizational charts, and provide background information and qualifications
of any contractors used to meet the terms of the ORDER
o Clause guaranteeing site access for employees, agents or contractors
of complainant to inspect and evaluate compliance with ORDER pursuant to
authority in §3007 of RCRA 42 USC §6927
o Requirement to develop Quality Assurance Project Plan in accordance with
EPA guidance document QAMS - 005/80.
o EPA idemnification clause
o Clause guaranteeing EPA's right to take or split samples
o Clause establishing EPA's ability to halt work if necessary
o Effective date
o Signature
€
6-12
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6.4 §3008(a) Orders
The §3008(a) process can accomodate the issuance of either phased or
technically-specific orders. In fact, a single order may incorporate both
approaches.
The process of issuing a §3008(a) order is diagrammed in Appendix B.
Briefly, the process involves the issuance of a complaint and compliance order
followed by negotiations (if desired by both parties), a hearing (if requested
by the respondent) and the issuance of a consent order or a final unilateral
order. If a respondent does not answer the complaint, (s)he become subject
to a default order. Generally, a respondent answers the complaint, requests
a hearing, and then either enters into a consent agreement with the Agency or
proceeds through the hearing and becomes subject to a final order issued
unilaterally.
If the Agency feels confident that a particular respondent will not
default, the compliance order issued with the complaint may include a
broadly-stated remedy such as "compliance with Part 265 Subpart F and Part
270." Since the respondent is required to undertake remedial activities
and/or pay any assessed penalty only after the consent order or final order
is issued, it is only in the consent or final order that specificity becomes
critical. Some Regions seem to prefer compliance orders with broadly-stated
remedies, although developing a phased compliance order, which would require
the respondent to develop detailed plans, should prove to be fairly simple
in most cases.
6-13
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The Regions should try to avoid the situation where a broadly-stated
compliance order is issued with the complaint, the respondent fails to answer,
and a default order is issued. In this case the terras of the compliance
order may become the terms of the default order. Although respondents do
not usually fail to answer complaints, especially when sizeable penalties
are involved, the Region should consider the possibility of a respondent
failing to answer, before deciding on a format for the compliance order.
The following describes in more detail the options available under
§3008(a):
OPTION (1): The Region may issue a complaint with a phased compliance
order, enter negotiations with the respondent and then follow one of several
courses of action, depending on whether a settlement is reached with the
respondent. If both parties are willing to settle and can reach agreement
on the remedy, a consent order may be negotiated in either a phased or a
technically-specific format, depending on how detailed the discussions have
been in negotiating sessions. If in the course of negotiations the facility
has filled in any gaps in the hydrogeologic study and the Region and respon-
dent have agreed on such details as the list of indicator parameters and the
location of wells, a consent order could be negotiated that specifies the
location of wells, construction specifications, etc. The order might also
specify sampling and analytical procedures and schedules, or it might require
the respondent to develop and submit a plan for sampling and analysis. As
noted in section 5.2, the Region might choose to enter into a consent agreement
only after completion of the remedial activities by the respondent. In such
6-14
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cases, the consent order should document, in detail, the work that has
been completed by the respondent.
If the parties are unable to reach settlement and a hearing takes place,
the Region will have the opportunity to submit a proposed final order to the
Presiding Officer. The proposed final order may be phased or may be tech-
nically specific, depending on the amount of information available to the
Region. In any case, the proposed order should not simply include a broad
mandate, like "the owner/operator must come into compliance with Part 265
Subpart F and Part 270." It should either specify a detailed remedy itself
or should require the owner/operator to develop a plan that specifies details.
Unless it is clear to both parties what the order requires, it will be diffi-
cult to determine whether the facility in fact achieves compliance. If
there is room for dispute as to what the order requires, it may be difficult
for the Agency to enforce the terms of the order, should that later become
necessary.
OPTION (2): The Region may issue a complaint with a proposed compliance
order that simply requires "compliance with Part 265 Subpart F and Part 270"
rather than a phased compliance order. The steps following complaint issuance
would be the same as those described in Option 1. Although it is acceptable
to put a broad remedy in the initial compliance order, the consent order or
proposed final order must contain specificity (or require the respondent to
propose the specifics). When the order goes into effect it must express
what "compliance" entails. As described earlier, the Region should not use a
vaguely-worded compliance order if there is a chance that the respondent will
not answer the complaint.
6-15
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6.5 §3013 Orders
Section 3013 orders can be Issued in either a one- or two-step process.
Both processes are adaptable to the Issuance of either phased or specific
orders. The one-step process involves one of the following:
o issuance of a phased order requiring the sequential development,
submittal, and execution of plans; or
o issuance of a technically-specific order, after the details are
worked out in negotiations with the respondent.
The two-step process involves the issuance of a preliminary order requiring
the development and subraittal of plans for approval, followed by the issuance
of an order requiring the execution of the plans as modified by the Agency.
The second order could be phased or specific, depending on the amount of
information available. For example, if the remedy sought by the Agency
included a significant amount of hydrogeologic investigation as well as
construction and sampling of wells, the preliminary order might require the
development of a plan for the hydrogeologic study and a schedule for the
development and implementation of plans for later stages of the remedy.
The second order would then require the owner/operator to conduct the hydro-
geologic work and then sequentially develop, submit, and carry out plans for
well construction and sampling.
Alternatively, the preliminary order could require the development of
well construction and sampling plans, which would entail conducting a hydro-
geologic investigation. The second order then would be able to specify
detail as to the locations and specifications of the wells and plans for
sampling and analysis.
6-16
f
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6.6 §3008(h) Orders
Section 3008(h) orders can accomodate both phased and specific orders in
a manner similar to that described in section 6.4 for §3008(a) orders.
6-17
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APPENDIX A:
MODEL PHASED ORDER FOR GROUND-WATER MONITORING
-------
EXAMPLE PHASED ORDER
Pursuant to Section(s) of the Resource Conservation and Recovery Act
(RCRA), 42 U.S.C. 69 it is ordered that shall comply with the
following requirements:
1. Within calendar days of the effective date of this ORDER, respondent
shall develop and submit for EPA approval a plan for conducting a hydro-
geologic investigation of the site. The plan should be designed to
provide the following information:
a. A description of the regional geologic and hydrogeologic characteristics
in the vicinity, including:
1) regional stratigraphy: description of strata including
strike and dip, identification of stratigraphic contacts,
petrographic analysis
2) structural geology: description of local and regional
structural features (e.g., folding, faulting, tilting,
jointing, etc)
3) depositional history
4) regional ground-water flow patterns
5) identification and characterisation of areas of recharge
and discharge
b. An analysis of any topographic features that might influence the
ground-water flow system (Note that stereoscopic analysis of aerial
photographs should aid in this analysis).
c. A classification and description of the hydrogeologic properties of
all the hydrogeologic units found at the site (i.e. , the aquifers and
any intervening saturated and unsaturated units), including:
1) hydraulic conductivity, effective porosity
2) lithology, grain size, sorting, degree of cementation
3) an interpretation of hydraulic interconnections between
saturated zones
A-l
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d. Using a topographic map or aerial photograph as a base, submit maps
of structural geology and at least four hydrogeologic cross sections
showing the extent (depth, thickness, lateral extent) of all hydro-
geologic units within the facility property, identifying:
1) sand and gravel deposits in unconsolidated deposits
2) zones of fracturing or channeling in consolidated
deposits
3) zones of higher permeability or lower permeability that might
direct or restrict the flow of contaminants
4) perched aquifers
5) the uppermost aquifer (includes all water-bearing zones
above the first confining layer that may serve as a pathway
for contaminant migration Including perched zones of satur-
ation)
e. A description of water level or fluid pressure monitoring including:
1) water-level contour and/or potentiometric maps
2) hydrologic cross sections showing vertical gradients
3) an interpretation of the flow system, including the
vertical and horizontal components of flow
4) an interpretation of any change in hydraulic gradients
due, for instance, to tidal or seasonal influences
f. A desciption of manmade influences that may affect the hydrogeology of
the site, identifying:
1) local water-supply and production wells with an approximate
schedule of pumping
2) manmade hydraulic structures (pipelines, french drains, ditches)
The plan should include a description of the field methods and other infor-
mation sources proposed for the study and a summary of which data will be col-
lected by each method. The proposed methods should include, but are not
limited to:
A program of soil borings, as required to adequately describe
the subsurface geology of the site. The program should provide
for the presence of a qualified geologist or geotechnical
A-2
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engineer to log and describe the materials encountered during
the boring. The program should also describe the methods pro-
posed to stabilize selected holes until monitoring wells are
installed.
b. A sufficient number of piezometers to characterize ground-water
depth and gradient (both horizontal and vertical) over the
entire area of the site.
c. The use of slug and/or pump tests as appropriate to determine
hydraulic conductivities
NOTE: Geophysical techniques, both borehole and surficlal, are effec
tive supplementary investigative techniques that should be
considered
The plan shall contain a schedule for conducting the proposed hydrogeologic
assessment and shall be submitted to:
Deputy Director, Air and Waste Management Division
Environmental Protection Agency
444 RCRA Way
Any town, USA 00001
2. Within _ calendar days of the effective date of this ORDER, respondent shall
develop and submit to EPA a list of proposed indicator parameters capable of
detecting leakage of hazardous waste or hazardous constituents into ground
water. The parameters should be representative of constituents at least as
mobile as the most mobile constituents that could reasonably be derived from
the facility's waste, and should be chosen after considering:
a. the types, quantities, and concentrations of constituents in wastes
managed at the facility;
b. the mobility, stability, and persistence of waste constituents or their
reaction products in the unsaturated zone beneath the waste management
area;
c. the detectability of the indicator parameters, waste constituents or
reaction products in ground water;
d. the concentration or value and the natural variation (known or suspected)
of the proposed monitoring parameter in background ground water.
The list should include the basis for selecting each proposed indicator
parameter, including any analyses or calculations performed. The basis
for selection must include chemical analysis of the facility's waste and/or
leachate as appropriate.
A- 3
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The list should also include parameters to characterize the site-specific
chemistry of ground water at the site, including but not limited to the
major anions and cations that make up the bulk of dissolved solids in
water (i.e., Cl~, Fe, Mn, Na+, S04, Ca+, Mg+, K*" N0~ , P04=, silicate,
ammonium).
3. Within calendar days of written approval by EPA, the respondent shall
promptly implement the hydrogeologic investigation plan according to the
terms and schedules contained therein.
4. Within calendar days after completion of the hydrogeologic investigation,
the respondent will submit to EPA a full report that provides the information
described in paragraph 1.
5. Also within days after the completion of the hydrogeologic investigation,
the respondent will submit to EPA a plan for the design and installation of
a monitoring well network that will meet the following requirements:
a. The upgradient wells must be capable of yielding samples that are
representative of background water quality in the uppermost aquifer
and are not affected by the facility. The number and location of the
wells must be sufficient to: 1) characterize the spatial variability
of background water; and 2) meet the needs of the statistical test
proposed pursuant to paragraph .
b. The downgradient wells must be capable of immediately detecting any
statistically significant amounts of hazardous waste or hazardous
constituents that migrate from the facilty into the uppermost aquifer.
c. The monitoring system should be designed to operate for a period of no
less than thirty years.
The plan should include the following elements:
a. A description and map of proposed well locations, including a survey
of each well's surface reference point and the elevation of its top
of casing.
b. Size and depth of wells;
c. Desciption of well-intake design, including screen slot size and length;
filter pack materials and method of filter-pack emplacement.
d. Type of proposed well casing and screen materials. The choice of well
materials should be made in light of the parameters to be monitored for
and the nature of the leachate that could potentially migrate from the
facility. The well materials should: 1) minimize the potential of
adsorption and desorption of constituents from the samples; and
2) maintain their integrity for the expected life of the system
(at least thirty years).
A-4
€
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e. Methods used to seal the well from the surface and prevent downward
migration of contaminants through the well annulus.
f. Description of the methods or procedures used to develop the wells.
6. Also within days after the completion of the hydrogeologic assessment,
the Respondent shall sumbit a sampling and analysis plan capable of
yielding representative samples for a comparison of up- and downgradient
wells. The plan should include the following elements:
a. Well evacuation procedures including volume to be evacuated prior to
sampling and handling procedures for purged well water
b. Sample withdrawal techniques. Sampling equipment and materials (tubing,
rope, pumps, etc.) shall be selected to yield representative samples in
light of parameters to be monitored for. The sampling protocol will
include field measurement of pH, conductivity, and temperature for
each sample.
c. Sample handling and preservation techniques including provision for
field-filtration of samples as appropriate.
d. Procedures for decontaminating sampling equipment between sampling
events.
e. Procedures for measuring ground-water elevations at each sampling
event
f. Chain of custody procedures to be used for all phases of sample
management.
g. Laboratory analytical techniques, including EPA-approved analytical
methods and quality assurance, detection levels, quality control
procedures.
h. Procedures for performing a comparison of upgradient and downgradient
ground water to determine whether contamination has occurred. The pro-
cedures should include:
1) A proposed method (statistical or otherwise) to compare up-
gradient and downdradient well water that provides a reasonable
balance between the probability of falsely identifying and
failing to identify contamination.
2) An accelerated sampling schedule to establish data for the
comparison. In no instance shall sampling exceed months.
3) A proposed method for data organization and presentation.
A-5
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7. By no later than days after EPA approval of the monitoring well network
plan, Respondent shall complete the installation of the monitoring well
network.
8. By no later than days after the installation of the monitoring well
network, Respondent shall implement the sample and analysis plan, perform
the comparison and submit the results to EPA for review.
9. If there is a statistically significant difference between upgradient and
downgradient well water, the Respondent will develop a ground-water asses-
sment plan capable of determining the following:
a. The extent of migration of hazardous constituents into ground water.
b. The concentration of each Appendix VIII constituent throughout the
plume or the maximum concentration of each Appendix VIII in the
plume.
c. Background concentrations for all Appendix VIII constituents detected
in ground water.
d. Waste/leachate characteristics including specific gravity, viscosity,
solubility in water, and octanol-water partition coefficient.
e. Soil properties including cation exchange capacity, organic content,
and temperature.
The plan should describe the methods proposed to accomplish the above
objectives including indirect and direct techniques. The sampling and
analysis plan developed pursuant to paragraph 6 should be revised to meet
the new objectives of this monitoring phase. The plan should include an
expeditious schedule for the implementation of the above assessment, and
should be submitted to EPA no later than 15 days after the confirmation of
leakage.
10. Within calendar days of EPA approval of the assessment plan, the Respondent
will begin to execute the plan according to the terms and schedules contained
therein. Within days of the completion of the assessment, the Respondent
will submit the results to the Agency, including all raw data collected, all
calculations performed, and an interpretation of the findings.
11. Based on the results of the ground-water assessment, the Respondent will
fulfill his/her obligations pursuant to §270.14(c)(7) or (8) by developing
a compliance monitoring and/or corrective action program as appropriate.
Respondent will submit whatever plans and engineering studies are necessary
to describe the proposed program to EPA no later than months after the
completion of the ground-water assessment described in paragraph nine. ^
A-6
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All plans, reports, and schedules required by the terras of this ORDER are,
upon approval by EPA, incorporated into this ORDER. Any noncorapliance with
such approved studies, reports, or schedules shall be termed noncompliance
with this ORDER.
13. In the event of Agency disapproval (in whole or in part) of any plan required
by this ORDER, EPA shall specify any deficiencies in writing. The Respondent
shall modify the plan to correct the deficiencies within days from receipt
of disapproval by EPA. The modified plan shall be submitted to EPA in
writing for review.
Should the Respondent take exception to all or part of EPA's disapproval, the
Respondent shall submit to EPA a written statement of the grounds Cor the
exception. Representatives of EPA and the Respondent may confer in person
or by telephone in an attempt to resolve any disagreement. If agreement
is reached, the resolution shall be written and signed by representatives
of each party. In the event that resolution is not reached within 15 days,
the Respondent shall modify the plan as required by EPA.
14. In the event that the respondent fails to:
a. Comply with the milestones contained in paragraphs 3, 7, 8, or 10;
b. Provide the plans and information described in paragraphs 1, 2, 4, 5,
6, 8, 9, 10, or 11;
(s)he shall pay stipulated penalties from the date of the violation as
follows:
a. $5000.00 per day for failure to comply with a milestone listed above;
b. $1000.00 per day for failure to provide a plan or information listed
above.
15. Notwithstanding compliance with the terms of this ORDER, Respondent may
be required to take further actions as necessary, including additional
ground-water monitoring, assessment, and/or corrective action, to come into
compliance with RCRA, or other applicable state or Federal laws.
A-7
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APPENDIX B:
DIAGRAM OF PART 22 ADMINISTRATIVE PROCEEDINGS
-------
0) -P V-4
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Complaint
and
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Order
Issued
B-l
-------
Ground-Water Monitoring
Technical Enforcement Guidance Document
Draft
August, 1985
-------
TABLE OF CONTENTS
Page
CHAPTER ONE. CHARACTERIZATION OF SITE HYDROGEOLOGY 1-1
1.1 investigatory Tasks for Hydrogeologic Assessments 1-2
1.2 Characterization of Subsurface Geology 1-5
1.2.1 Site Characterization Boring Program 1-6
1.2.2 Interpretation of Subsurface Geology 1-16
1.2.3 Presentation of Geologic Data 1-17
1.3 Identification of Ground-Water Flowpaths 1-20
1.3.1 Determining Ground-Water Flow Directions 1-20
1.3.1.1 Ground Water Level Measurements 1-22
1.3.1.2 Interpretation of Ground-Water Level Measurements ... 1-23
1.3.1.3 Establishing Vertical Components of Ground-Water
Flow 1-25
1.3.1.4 Interpretation of Flow Direction 1-27
1.3.2 Seasonal and Temporal Factors: Ground-Water Flow 1-29
1.3.3 Determining Hydraulic Conductivities 1-30
1.4 Identification of the Uppermost Aquifer 1-33
CHAPTER TWO. PLACEMENT OF DETECTION MONITORING WELLS 2-1
2.1 Placement of Downgradient Detection Monitoring Wells 2-3
2.1.1 Location of Wells Relative to Waste Management Areas .. 2-3
2.1.2 Horizontal Spacing Between Downgradient Monitoring
Wells 2-5
2.2 Depth of Wells/Vertical Sampling interval(s) 2-15
2.2.1 Depth of Wells 2-15
2.2.2 Thickness of the Vertical Sampling Interval(s) 2-15
2.3 Placement of Upgradient (Background) Monitoring Wells 2-24
CHAPTER THREE. MONITORING WELL DESIGN AND CONSTRUCTION 3-1
3.1 Drilling Methods 3-1
3.1.1 Hollow-stem Continuous-Flight Auger 3-3
3.1.2 Solid-Stem Continuous-Flight Auger 3-3
3.1.3 Cable Tool 3-4
3.1.4 Air Rotary 3-4
3.1.5 Water Rotary 3-5
3.1.6 Mud Rotary 3-6
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TABLE OF CONTENTS
(Continued)
3.2 Monitoring Well Construction Materials 3-6
3.2.1 Well Casings and Well Screen 3-1
3.2.2 Monitoring Well Filter Pack and Annular Sealant 3-11
3.3 Well Intake Design 3-12
3.4 Well Development 3-13
3.5 Documentation of Well Design and Construction 3-15
3.6 Specialized Well Designs 3-15
3.7 Evaluation of Existing Wells 3-18
CHAPTER FOUR. SAMPLING AND ANALYSIS 4-1
4.1 Elements of Sampling and Analysis Plans 4-2
4.2 Sample Collection 4-3
4.2.1 Measurement of Static Water Level Elevation 4-3
4.2.2 Detection of Immiscible Layers 4-3
4.2.3 Well Evacuation 4-5
4.2.4 Sample Withdrawal 4-7
4.2.5 In-Situ or Field Analyses 4-9
4.3 Sample Preservation and Handling 4-10
4.3.1 Sample Containers 4-11
4.3.2 Sample Preservation 4-13
4.3.3 Special Handling Considerations 4-13
4.4 Chain of Custody 4-18
4.4.1 Sample Labels 4-18
4.4.2 Sample Seal 4-19
4.4.3 Field Logbook 4-19
4.4.4 Chain-of-Custody Record 4-19
4.4.5 Sample Analysis Request Sheet 4-20
4.4.6 Laboratory Logbook 4-20
4.5 Analytical Procedures 4-20
4
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TABLE OF CONTENTS
(Continued)
Page
4.6 Field and Laboratory Quality Assurance/Quality Control 4-21
4.6.1 Field QA/QC Program 4-21
4.6.2 Laboratory QA/QC Program 4-22
4.7 Evaluation of the Quality of Ground-Water Data 4-22
4.7.1 Reporting of Low and Zero Concentration Values 4-23
4.7.2 Significant Digits 4-28
4.7.3 Missing Data Values 4-30
4.7.4 Outliers 4-31
4.7.5 Units of Measure 4-32
CHAPTER FIVE. STATISTICAL ANALYSIS OF DETECTION MONITORING DATA .. 5-1
5.1 Methods for Presenting Detection Monitoring Data 5-1
5.2 Introductory Topics: Available t-Tests, Definition of Terms,
and Components of Variability 5-1
5.3 Statistical Analysis of the First Year's Data 5-4
5.4 Statistical Analysis of Detection Monitoring Data After the
First Year 5-5
5.4.1 Comparison of Background Data Collected the First Year
With Upgradient Data Collected in Subsequent Years .... 5-5
5.4.2 Comparison of Background Data Collected During the
First Year With Downgradient Data Collected in
Subsequent Years 5-7
CHAPTER SIX. ASSESSMENT MONITORING 6-1
6.1 Description of Hydrogeologic Conditions 6-3
6.2 Description of Detection Monitoring System 6-4
6.3 Description of Approach for Making First Determination -
False Positives 6-5
6.4 Description of Approach for Conducting Assessment 6-7
6.4.1 Use of Direct Methods 6-8
6.4.2 Use of Indirect Methods 6-8
6.4.3 Mathematical Modeling of Contaminant Movement 6-10
t
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TABLE OF CONTENTS
(Continued)
6.5 Description of Sampling Number, Location, and Depth 6-12
6.5.1 Collection of Additional Site Information 6-13
6.5.2 Sampling Density 6-14
6.5.3 Sampling Depths 6-l"7
6.6 Description of Monitoring Well Design and Construction 6-18
6.7 Description of Sampling and Analysis Procedures 6-20
6.8 Procedures for Evaluating Assessment Monitoring Data 6-22
6.8.1 Listing of the Data 6-23
6.8.2 Summary Statistics Tables 6-26
6.8.3 Data Simplification 6-31
6.8.4 Graphic Displays of Data 6-33
6.8.4.1 Plotting Data Over Time 6-33
6.8.4.2 Plotting Data on Maps 6-33
6.9 Rate of Migration 6-36
6.10 Reviewing Schedule of Implementation 6-41
GLOSSARY
APPENDICES
A. Evaluation Worksheets
B. Methodology and Example Applications That Describe the Use of
Cochran's Approximation to the Behrens-Fisher and the Averaged
Replicate t~Tests
C. Description of Selected Geophysical Methods and Organic Vapor Analysis
f
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LIST OF TABLES
1-1. Hydrogeologic Investigatory Techniques 1-3
1-2. Factors Influencing Boring Well spacing 1-7
1-3. Suggested Laboratory Methods for Core Samples 1-11
2-1. Factors Used to Adjust Horizontal Spacing of Monitoring
Wells 2-6
2-2. Factors Affecting Number of Wells Per Location (Clusters) ... 2-17
3-1. Drilling Methods for Various Types of Geologic settings 3-2
4-1. Sampling and Preservation Procedures for Detection
Monitoring 4-14
4-2. A Listing and Description of Codes Used to Indicate That
Pollutant Concentrations Were Below a Concentration Which
Can Be Measured Accurately or That The Pollutants Were Not
Present 4-25
4-3. An Example of a Data Submission Which May Be Concealing an
Increasing Concentration Trend or Where the Units of Measure
Were Reported Incorrectly 4-27
4-4. Examples of Data Values and Their Associated Number of
Significant Digits 4-29
6-1. An Example of How Assessment Monitoring Data Should be
Listed 6-25
6-2. An Example of How Data Should be Summarized by GWCC 6-28
6-3. An Example of How Data Should be Summarized by GWCC/Well
Combination 6-29
6-4. An Example of How Data Should Be Summarized by GWCC/Well/
Date Combination 6-30
6-5. An Example of How Ranks of the Mean Concentrations for Each
GWCC/Well Combination Can Be Used to Simplify and Present
Concentration Data collected for a Variety of GWCCs in a
Number of Monitoring Wells 6-32
-------
LIST OF FIGURES
Page
1 Overview of the Enforcement Process 6
1-1. Field Boring Log Information 1-10
1-2. Progressive Boring Approach: Scenario 1 1-14
1-3. Progressive Boring Approach: Scenario 2 1-15
1-4. Geologic Cross Section Survey Plan 1-18
1-5. Example of an Acceptable Geologic Cross Section 1-19
1-6. Example of a Site Map 1-21
1-7. Potentiometric Surface Map 1-24
1-8. Example of Improper Well Placement Based Upon Flow
Components 1-25
1-9. Cross Sectional View Illustrating Flow Nets 1-28
1-10. Example of Hydraulic Interconnection Between Water-Bearing
Units 1-35
1-11. An Example of Hydraulic interconnection Caused by
Fracturing 1-37
1-12. Perched Water Zones as Part of the Uppermost Aquifer 1-38
1-13. An Example of an Undetected, Structurally Complex
Uppermost Aquifer 1-39
1-14. An Example of an Undetected Portion of the Uppermost
Aquifer (Permeable Sandstone Unit Near a Coastal Area) 1-41
1-15. Example of a Contaminant That May Affect the Quality
of a Confining Layer 1-42
2-1. Dowgradient Wells Immediately Adjacent to Hazardous Waste
Management Units 2-4
2-2. Well Spacing Based Upon Waste Character 2-8
2-3. Wei 1 spacing Based on Site Geology 2-9
2-4. Well Placement Based Upon Locally Inundated Areas 2-11
2-5. Well Placement Based Upon a Change of Preferential Routes
of Migration 2-12
2-6. Well Placement Based Upon Structural Fracturing 2-13
2-7. Well Placement Based Upon Age and Waste Character 2-14
2-8. Example of Wider Monitoring Well Spacing Due to the Use
of Supplementary Investigative Techniques 2-19
2-9. Well Depth Determination Based Upon Flow-Net Analysis 2-21
2-10. Well Placement Based Upon Flow-Net Analysis 2-22
2-11. Well Placement Based Upon Changes in Geology 2-23
2-12. Well Placement Based Upon Complex Geology 2-25
2-13. Well Depth Based Upon Possible Hydraulic Connection 2-26
2-14. Placement of Background Wells 2-29
3-1. General Monitoring Well - Cross Section 3-8
3-2. Composite Well Construction (Inert Construction Materials
in Saturated Zone) 3-10
(Continued)
4
-------
LIST OF FIGURES
(Continued)
3-3. Decision for Turbid Ground-Water Samples 3-14
3-4. Monitoring Well Cross Section—Dedicated Positive Gas
Placement Bladder Pump 3-17
3-5. Monitoring Well Cross Section—Dedicated Positive Gas
Displacement Bladder Pump and Subcasing for Discrete
Sampling of Light Phase immiscible Layers 3-19
3-6. Monitoring Well Cross section—Dedicated Positive Gas
Displacement Bladder Pump and Subcasing for Discrete
Sampling of Dense Phase Immiscible Layers 3-20
6-1. Procedure for Evaluating False Positive Claims by
Owner/Operators 6-6
6-2. initial Placement of Well Clusters to Define the Extent
of Contamination in the Horizontal Plane 6-16
6-3. Vertical Well Cluster Placement 6-19
6-4. Selection of Plume Characterization Parameters for Units
Subject to Part 265 and Part 270 6-21
6-5. Plot of Chromium Concentrations Over Time (Well 9A) 6-34
6-6. Chromium and Lead Concentrations Over Time (Well 9A) 6-35
6-7. General Schematic of Multiphase Contamination in a sand
Aquifer 6-38
-------
CHAPTER ONE
CHARACTERIZATION OF SITE HYDROGEOLOGY
The adequacy of an owner/operator's ground-water monitoring program
hinges, in large part, on the quality and quantity of the hydrogeologic
data the owner/operator used in designing the program. Enforcement
officials, therefore, should evaluate the adequacy of an owner/operator's
hydrogeologic assessment as a first step towards ascertaining the overall
adequacy of the detection and/or assessment monitoring network. Clearly,
if the design of the well system is based upon poor data, the system
cannot fulfill its intended purpose.
In performing this evaluation, enforcement officials should ask
themselves two questions.
• Has the owner/operator collected enough information to: (1) have
an understanding sufficient to identify potential contaminant
pathways and (2) support the placement of wells capable of
determining the facility's impact on the uppermost aquifer?
• Did the owner/operator use appropriate techniques to collect and
interpret the information used to support well placements?
The answer to each question will, of course, depend on site specific
factors. For example, sites with more heterogenous subsurfaces will
require more hydrogeologic information to provide a reasonable assurance
that well placements will intercept contaminant migration. Likewise,
investigatory techniques that may be appropriate in one setting (given
certain waste characteristics and geologic features), may be
inappropriate in another.
This chapter is designed to help enforcement officials answer the
above questions. It identifies various investigatory techniques that are
necessary for an owner/operator to adequately characterize a site and
explores the factors that enforcement officials should consider when
1-1
-------
evaluating whether the particular investigatory program an owner/operator
used was appropriate in a given case. Enforcement officials should also
find this chapter useful when constructing compliance orders that include
hydrogeologic investigations.
1.1 Investigatory Tasks for Hydrogeologic Assessments
In carrying out a hydrogeologic investigatory program, owner/
operators should accomplish two tasks:
1. define the subsurface geology/materials; and
2. identify ground-water flow paths and rates.
A variety of investigatory techniques are available to achieve these
goals and enforcement officials must evaluate whether the combination of
techniques used by the owner/operator was adequate given the site
specific factors at his/her facility.
There are certain investigatory techniques that all owner/operators,
at a minimum, should have used to characterize their sites. Table 1-1
illustrates the universe of techniques that an owner/operator may use to
perform hydrogeologic investigations. Those techniques that the owner/
operator, at a minimum, should have used to define the subsurface geology
or identify ground-water flow paths are identified with astericks.
Table 1-1 also presents preferred methods for presentation of the
data generated from a hydrogeologic assessment. An owner/operator who
has performed the level of site characterization that is necessary to
design adequate ground-water monitoring programs will be able to supply
any of the outputs (cross sections, maps, etc.) listed in the last column
of Table 1-1 at an appropriate level of specificity.
The owner/operator's investigatory program should have included
direct (e.g., borings, piezometer wells, geochemical analysis of soil
samples) methods of determining the site hydrogeology. Indirect methods
(e.g., aerial photography, ground penetrating radar, resistivity).
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especially geophysical studies, may provide valuable sources of informa-
tion that can be used to extrapolate geologic data between points where
measurements with direct methods were made. However, pre-existing
information or indirect methods will not alone have provided the detailed
information necessary. The owner/operator's investigatory program will
likely have combined the use of direct and indirect techniques and should
have resulted in the complete characterization of the facility, including
an identification of:
• the subsurface geology below the owner/operator's hazardous waste
facility:
• the vertical and horizontal components of flow in the uppermost
saturated zone below the owner/operator's site;
• the hydraulic conductivity of the uppermost saturated zone; and
• the vertical extent of the uppermost saturated unit down to the
first confining layer.
The following sections outline the basic steps an owner/operator should
have followed to implement an adequate site hydrogeologic study, and
detail the methods that the owner/operator should have used to collect
and present site hydrogeologic data.
1.2 Characterization of Subsurface Geology
In order to adequately detail the subsurface geology of the site,
the owner/operator should have collected direct information identifying
the lithology and structural characteristics of the subsurface. Indirect
methods of geologic investigation such as geophysical studies, may be
used to verify the evidence gathered by direct field methods but should
not be used as a substitute for them. Geophysical studies such as
seismic reflection, seismic refraction, geophysical well logging, and
resistivity measurements may yield valuable information on the depth to
bedrock, the types of unconsolidated material present in the subsurface
soil and above bedrock, the presence of fracture zones or structural
1-5
-------
discontinuity, and the depth to the water table. Additionally, geophysi-
cal methods may have their greatest utility in correlating the continuity
of subsurface materials between boreholes. However, geophysical methods
should have been used primarily to substantiate information obtained from
direct sources, and in order to adequately characterize the lithology and
geologic characteristics of the subsurface, the owner/operator should
have used direct means of gathering hard data concerning the subsurface
geologic constituents at the site. Specifically, all owner/operators
should have implemented a site characterization boring program sufficient
to characterize the subsurface geology below the the site.
1.2.1 Site Characterization Boring Program
The enforcement officer should determine whether an owner/operator's
boring program was adequate to gather the information necessary to
characterize the subsurface geology. Such a program should have entailed
the installation of borings:
• at a preferred spacing of 300 feet. (Boring spacing may vary
from this horizontal distance based on criteria described in
Table 1-2.)
• that have been drilled to the depth of the first confining unit
below the uppermost zone of saturation.
• that have continuous sample corings that have been logged in the
field by a qualified geologist.
• that have had sufficient laboratory analysis to provide
information as to the petrographic variation, mineralogic
variation, sorting (for sedimentary units), moisture content and
intrinsic permeability of each geologic unit or soil zone.
The final spacing between boreholes in an owner/operator's charac-
terization program will ultimately, of course, depend upon site specific
conditions. Usually, the boring program will be a progressive investiga-
tion where results from initial phases of study will guide subsequent
decisions. For example, spacings between borings in the early phase of
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the program may start at 300 feet. The information subsequently
generated could dictate closer borings over part of the site and wider
spacings between borings on other parts of the site.
The owner/operator should characterize site geology to the depth of
the first confining layer below the uppermost saturated zone or ten feet
into bedrock. This requires borings to be drilled to this depth. The
owner/operator should drill enough borings to this depth to establish
that the confining layer extends laterally across the entire site, is of
sufficient thickness, and is sufficiently impermeable to impede the
migration of contaminants to any stratigraphically lower, water-bearing
units. (Refer to the glossary for the definition of confining layer.)
It should be noted by the enforcement official that chemical bridging and
transfer across, or chemical reaction with confining layer material, can
occur. Therefore, the owner/operator should have addressed this problem
by considering chemical compatibility of site-specific waste types and
the geologic materials of the confining layer.
All coring samples should have been logged in the field by a quali-
fied geologist (see glossary). These sample corings should have been
collected with a shelby tube or split spoon sampler and represent a
continuous coring of the subsurface. Drilling logs should have been
prepared which detail the following information:
• gross petrography (e.g., rock type) of each geologic unit;
• gross mineralogy of each geologic unit;
• gross structural interpretation of each geologic unit and
structural features crossing geologic stratum bioturbation
(e.g., fractures, gouge material, solution channels, buried
streams or valleys, etc.) including, when applicable,
identification of depositional material;
• development of soil zones and vertical extent and description of
soil type;
• depth of water bearing unit(s) and vertical extent of each;
1-8
-------
• depth and reason for termination of borehole; and
• depth and location of any contaminant encountered in bore-
hole. (Samples should have been collected and analyzed for
Appendix VIII constituents in accordance with requirements of
SW-846.)
Figure 1-1 identifies the minimum required information that should have
been included in a drilling log. These items are marked with astericks.
In addition to field descriptions as described above, the owner/
operator should have provided laboratory analysis of each geologic unit
and soil zone. These analyses should contain the following information:
• mineralogy and mineralogic variation of each geologic unit (e.g.,
microscopic analysis and other methods such as X-ray diffraction
as necessary);
• petrology and petrologic variation of each unit (e.g. petrographic
analysis, other laboratory methods for unconsolidated materials)
to determine:
- degree of crystallinity and cementation of matrix
- degree of sorting, size fraction, textural variation
- rock type(s)
- soil type
- approximate bulk geochemistry
- existence of microstructures that may effect or indicate
fluid flow
• moisture content and moisture variation of each soil zone and
geologic unit; ar.d
• intrinsic permeability and variation of each soil zone and type
and geologic unit in the unsaturated zone (indirect methods are
not appropriate to determine hydraulic conductivity in the
saturated zone, Section 1.3.2).
A table which describes the laboratory analysis methods necessary to
provide adequate information to detail these laboratory parameters is
shown in Table 1-3.
From a procedural standpoint, an owner/operator may opt to develop
a scheme for selecting borehole locations in a step-wise or progressive
1-9
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FIGURE 1-1
FIELD BORING LOG INFORMATION
General
• Project name
*• Hole name/number
*• Date started and finished
*• Geologist's name
*• Driller's name
• Sheet number
*• Hole location; map and
elevation
*• Rig type
bit size/auger size
Information Columns
*• Depth
*• Sample location/number
• Blow counts and advance rate
*• Percent sample recovery
*• Narrative description
Narrative Description
• Geologic observations:
*_
*_
*_
rock type
*- color
gross mineralogy
gross petrography
- friability
*- moisture content
• Drilling Observations:
- loss of circulation
*- advance rates
- rig chatter
*- water levels
- amount of air
used
• Other Remarks:
- equipment failures
*- possible sources of contamination
*- deviations from drilling plan
*- weather
*Indicates items that the owner/operator should record, at a minimum.
*- crystalinity
*- presence of
carbonate (HCL)
*- fractures
*- solution cavities
*- bedding
*- drilling
difficulties
*- changes in drilling
method or equipment
*- depositional
structures
*- organic content
*- odor
*- suspected
contaminant
ammounts and type
of any liquids
used
running sands
caving/hole
stability
*_
*_
1-10
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TABLE 1-3
SUGGESTED LABORATORY METHODS FOR CORE SAMPLES
Sample Origin
Parameter
Laboratory Method
Used to Determine
Unsaturated zone
Geologic formation,
unconsolidated
sediments, consoli-
dated sediments,
sol urn
Contaminated sample
corings (e.g., soils
producing higher
than background
organic vapor
readings)
Intrinsic permeability
Size fraction
Sorting
Specific yield
Specific retention
Mineralogy
Bulk geochemistry
Crystallinity
Roundness of grains
Bedding
Lamination
Jointing
Fracturing
Sorting
Solution features
Appendix VIII
Parameters
(§261)
Falling head, static
head test
Sieving
Settling measurements
Petrographic analysis
Column drawings
Centrifuge tests
Petrographic analysis
X-ray diffraction
Petrographic analysis
Petrographic analysis
Petrographic analysis
Petrographic analysis
Petrographic analysis
Petrographic analysis
Petrographic analysis
Petrographic analysis
SW-846
Hydraulic conductivity
Hydraulic conductivity
Hydraulic conductivity
Porosity
Porosity
Soil type, rock type,
geochemistry, poten-
tial flow paths
1-11
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approach. A feature of this technique is that data and observations
derived from previous boreholes are used to establish the location for
the next boring. In this way, the general 300-foot borehole spacing
guideline may be varied depending on the conditions encountered and
logged in the previous boreholes. Such a progressive boring program is
described below.
First, the owner/operator should project a grid pattern with a
300-foot interval across the site. Second, the owner/operator should
initiate the boring and site characterization program, at one of the grid
intersection points near the waste management area. After the completion
of the first few borings, the owner/operator should check drill logs for:
• correlation of geologic profiles between soil borings;
• identification of zones of high potential hydraulic conductivity;
• indication of unusual or unpredicted geologic features such as
fault zones, fracture traces, facies changes, dissolution
features, buried channels, cross cutting structures, pinch out
zones, etc.; and
• continuity of petrographic features such as sorting, grain size
distribution, cementation, etc.
If the owner/operator is unable to adequately define such structural
anomalies, zones of potential high conductivity, or to correlate
petrographic features and/or geologic profiles between any two adjacent
boreholes then additional intermediate boreholes should be drilled. The
suggested method would be to drill intermediate boreholes, at a spacing
of 150 feet and at successively shorter spacing intervals until the
criteria outlined in the above bulleted items was adequately addressed.
On the other hand, if the bulleted parameters are achieved at the
300-foot spacing, it would be appropriate to switch to a wider spacing of
600 feet between adjacent boreholes. If at the 600-foot interval the
criteria are again met, it would again be acceptable to switch to a wider
grid spacing.
1-12
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Figure 1-2 illustrates a site where an owner/operator initiated a
progressive boring program. The first four borings were drilled in an
area adjacent to the site that the owner/operator considered to be down-
gradient and thus critical to his characterization program. Drilling
indicated thick massive marine sediments below a thin poorly developed
soil zone. Geologic units were highly correlated and indicated little or
no lateral variation in petrographic or structural components. A bedrock
basement was identified in all borings and structural components of the
basement/sediment interface were well defined. At this point the owner/
operator switched to a wider spacing of 600 feet between boreholes.
Additional borings indicated very little lateral variation and the owner/
operator was justified in terminating borings at a 1200-foot interval.
At a second site, (see Figure 1-3) the owner/operator initiated his
soil boring in a similar manner to that described in the first example.
However, the geologic environment was more complex in nature, such as
that of a fluvio-glacial depositional environment. Initial borings
indicated that the subsurface was highly variable. Attempted correlation
of buried structural features of high permeability and potential confin-
ing layers were inconsistent between boreholes. The owner/operator in
this case switched to a shorter boring spacing of 150 linear feet. At
this interval, the owner/operator was able to define some continuity
between boreholes and structural features. These were still erratic but
correlation between boreholes indicated that zones of high permeability
and low permeability had been defined. Also at this point, the owner/
operator was able to roughly determine the general ground-water direc-
tional flow and decided to concentrate further studies at the downgradient
side of the waste management area. The owner/operator, at this point,
initiated a geophysical surface resistivity study at the downgradient
side of the waste management area and was able to support existing boring
data with structural geophysical interpretation.
1-13
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300'
17
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GROUND-WATER
14
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FACILITY BOUNDARY
LEGEND
FIRST PHASE CHARACTERIZATION BORINGS
SECOND PHASE CHARACTERIZATION BORINGS
FIGURE 1-2 PROGRESSIVE BORING APPROACH : SCENARIO 1
1-14
-------
300'
f
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LEGEND
O FIRST • PHASE CHARACTERIZATION BORINGS
0 SECOND • PHASE CHARACTERIZATION BORINGS
^ INDICATED DIRECTION OF GROUND-WATER
FLOW
... GEOPHYSICAL TRAVERSE
FIGURE 1-3 PROGRESSIVE BORING APPROACH: SCENARIO 2
1-15
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1.2.2 Interpretation of Subsurface Geology
The enforcement official should review the owner/operator's geologic
characterization and verify:
• completeness of the narrative and the accuracy of the
owner/operator's interpretation, and
• that the geologic assessment addresses or provides means to
resolve any information gaps that may be suggested by the
geologic data.
In order to assess the completeness and accuracy of the owner/
operator's narrative, the enforcement geologist should:
• examine and evaluate the raw data;
• compare his own interpretation based on the raw data alone,with
that of the owner/operator; and
• identify information gaps that relate to incomplete data and/or
to narrative presentation.
The enforcement officer should independently conduct the following
tasks to support and develop his interpretation of the site geology:
• review drilling logs and identify major rock or soil types and
establish their horizontal and vertical variability;
• construct representative cross sections from well log data;
• identify zones of suspected high permeability, or structures
likely to influence contaminant migration through the unsaturated
and saturated zones;
• review laboratory data and determine whether laboratory data
adequately corroborates field data and that both are sufficient
to define petrography and petrographic variation; and
• review mineralogic data and the owner/operator's assessment of
general subsurface geochemistry and determine corroboration
between analytic and field data.
After the enforcement official has interpreted the geologic data,
the results should be compared to the results developed by the
owner/operator. The enforcement official should:
1-16
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• identify information gaps between narrative and data. Determine
whether resolution requires collection of additional data or
re-assessment of existing data; and
• identify any information gaps that will effect the owner/
operator's ability to have adequately located his/her moni-
toring well system.
1.2.3 Presentation of Geologic Data
In addition to the generation and interpretation of site specific
geologic data, the enforcement officer should review the owner/operator's
presentation of data in geologic cross sections, topographic maps and
aerial photographs. In part this requires that the enforcement officer
to review the data and determine qualitatively whether information is
accurate.
A minimum of four geologic cross sections should be presented by
an owner/operator. These cross sections should adequately depict major
geologic or structural trends and reflect geologic/structural features in
relation to ground-water flow. As such, geologic cross sections should
delineate such features in an orthogonal boxwork (see Figure 1-4) but
nonlinear structural features or complex ground-water patterns may
necessitate additional cross sections and/or nonorthogonal cross section
presentation.
On each cross section, the owner/operator should have identified:
the types and characteristics of the geologic materials present, the
contact zones between different geologic materials, zones of high
permeability or fracture, the location of each borehole, depth of
termination, the screen location, and depth to the zone of saturation.
If the owner/operator is unable to supply such details, the subsurface
study may be inadequate. Figure 1-5 illustrates a typical, geologic
cross section.
Additionally, surficial features may affect the subsurface hydro-
geology. An owner/operator should have provided a surface topographic
1-17
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GROUND-WATER
FLOW
CROSS SECTION TRACES
WASTE
DISPOSAL
UNIT
CROSS SECTION TRACES
PROPERTY BOUNDARY
SCALE (FEET)
400
0 100* 200' 300' 400'
LEGEND
BORING
FIGURE 1-4 GEOLOGIC CROSS SECTION SURVEY PLAN
1-18
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map and aerial photograph of the site. The topographic map should have
been constructed by a licensed surveyor and should provide contours at a
maximum two-foot contour interval, locations and illustrations of man-made
features (e.g., parking lots, factory buildings, drainage ditches, storm
drains, pipelines, etc.), descriptions of nearby water bodies and/or off
site wells, site boundaries, individual RCRA units, delineation of the
waste management areas, and well and boring locations. An example of a
site map is depicted in Figure 1-6. An aerial photograph of the site
should depict the site and adjacent off-site features. This photograph
should have the site clearly labeled. In addition, surface water bodies
and adjacent municipalities or residences should be labeled.
1.3 Identification of Ground-Water Plowpaths
In addition to evaluating the owner/operator's characterization of
subsurface geology, enforcement officials must decide whether owner/
operators have adequately identified ground-water flowpaths. To have
adequately identified flowpaths, owner/operators must have:
• established the direction of ground-water flow (including both
horizontal and vertical components of flow);
• established the seasonal, temporal, and artificially induced
(i.e., off-site production well pumping, agricultural use)
variations in ground-water flow; and
• determined the hydraulic conductivities of the hydrogeologic
units underlying their site.
In addition, enforcement officials must ensure that owner/operators used
appropriate methods for obtaining the above information.
1.3.1 Determining Ground-Water Flow Directions
To locate wells so as to provide upgradient and downgradient well
samples, owner/operators should have a thorough understanding of how
ground water flows beneath their facility. Of particular importance is
the direction of ground-water flow and the impact that external factors
1-20
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(intermittent well pumping, temporal variations in recharge patterns,
etc.) may have on ground-water patterns. In order for an owner/operator
to have assessed these factors, a program should have been developed and
implemented for precise well water level monitoring. This program should
have been structured such that it provides precise well water level
measurements in a sufficient number of wells and at a sufficient
frequency to adequately gauge both seasonal average flow directions and
to account for seasonal or temporal fluctuation of flow directions.
In addition to considering the components of flow in the horizontal
direction, a methodology or program should have been undertaken by the
owner/operator that accurately and directly assessed the vertical compo-
nents of ground-water flow. Ground-water flow information should not
be based on indirect data alone. Enforcement officials should review
independently an owner/operator's methodology for obtaining information
on ground-water flow and account for factors that may impact or
complicate ground-water flow at the facility. The following sections
detail the methods by which an owner/operator should have assessed the
vertical and horizontal components of flow at the site.
1.3.1.1 Ground water level measurements
In order for the owner/operator to have initially determined the
elevation of the water table in any boring well, several criteria should
have been considered by the owner/operator.
• The well casing height should have been measured by a licensed
surveyor to an accuracy of 0.1 feet. This may have required the
placement of a geologic benchmark on the facility property.
• All well water level measurements from boring or piezometer wells
used to construct a single potentiometric surface should have
been collected within a twenty-four hour period.
• The method used to measure well water levels should have been
adequate to attain an accuracy of 0.1 feet.
1-22
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• Well water levels should have been allowed to stabilize for
a minimum of twenty-four hours after well construction and
development, prior to measurement. In low yield situations,
recovery may take longer.
If an owner/operator cannot produce accurate documentation or
provide assurance that these criteria were met during the collection of
well water level measurements, this may indicate that the generated
information may be of questionable validity.
1.3.1.2 Interpretation of ground-water level measurements
After the enforcement official has assured that the well water level
data is valid, he should proceed to independently interpret the
information. The enforcement official should:
* use the owner/operator's raw data to construct a potentiometric
surface map (see Figure 1-7). The data used to develop the
potentiometric map should be data from wells screened at
equivalent stratigraphic horizons in the saturated zone;
• compare this data with that of the owner/operator's and deter-
mine whether the owner/operator has accurately presented the
information and determine if the information is sufficient to
describe ground-water flow trends; and
• identify any information gaps.
In reviewing this information, the enforcement officer should now
have an approximate idea of the general flow direction; however, in order
to have properly located monitoring wells, the owner/operator should have
established flow directions in both the horizontal and vertical directions.
1.3.1.3 Establishing vertical components of ground-water flow
In order for the owner/operator to have determined the direction of
flow, vertical components of flow must have been directly determined. To
illustrate the importance of vertical flow in determining overall ground-
water flow, an example is illustrated in Figure 1-8. In this situation,
the owner/operator has constructed a downgradient monitoring well in what
1-23
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1-25
-------
would first appear to an appropriate location. The well site selection
was based on a potentiometric surface developed from a data base of well
measurements. The owner/operator determined the general direction of
flow utilizing this information. Although this well placement may have
at first appeared to be appropriate, the flowpaths below the hazardous
waste unit are almost vertical and the well as depicted here would not
intercept a contaminant flowpath from the contaminant source. Thus, it
is necessary that the owner/operator assess the vertical components of
flow at the regulated site as well as horizontal components.
In order to collect this information the owner/operator should have
utilized direct means to determine vertical flow components. This will
have required the installation of piezometers in well clusters. In order
to have obtained reliable measurements the following criteria should be
considered in the placement of piezometer clusters.
• Information obtained from multiple piezometer placement in single
boreholes may generate erroneous data. Placement of vertically
nested piezometers in closely spaced separate boreholes is the
preferred method.
• Piezometer measurements should have been collected within a
twenty-four hour period if measurements are to be used in any
correlative presentation of data.
• Piezometer measurements should have been determined along a
minimum of two vertical profiles across the site. These profiles
should be cross sections roughly parallel to the direction of
ground-water flow indicated by the potentiometric surface.
When reviewing piezometer information obtained from multiple
placement of piezometers in single boreholes, the enforcement official
should closely scrutinize the construction details for the well. It is
extremely difficult to adequately seal several piezometers at discrete
depths within a single borehole and special design considerations should
have been considered by the owner/operator. If information is not
available that details design features, it may indicate that adequate
1-26
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construction considerations have not been used. Placement of piezometers
in closely spaced well clusters, where piezometers have been screened at
different, discrete depth intervals is more likely to produce accurate
information. Additionally, multiple well clusters sample a greater
proportion of the aquifer and thus may provide a greater degree of
accuracy for considerations of vertical potentiometric head in the
aquifer as a whole.
The information obtained from the piezometer readings should have
been used by the owner/operator to construct flow nets (see Figure 1-9).
These flow nets should include information as to piezometer location and
depth and width of screening. The flow net in Figure 1-9 was constructed
from information obtained from piezometer clusters screened at different,
discrete intervals. The construction of contours is straightforward and
the enforcement official should be able to verify the accuracy of the
owner/operator's presentation. The enforcement official should either
construct a flow net independently from the owner/operator's data or
spot-check the owner/operator's presentation. It is also important to
verify that the screened interval is accurately portrayed and to determine
whether the piezometer is actually monitoring the water table elevation
caused by the hydrostatic pressure of the desired water bearing unit.
If there is reasonable concurrence between the information presented
by the owner/operator and the enforcement officer's interpretation, the
enforcement officer should next interpret the flow directions from the
waste management area.
1.3.1.4 Interpretation of flow direction
In considering flow directions established by the owner/operator,
the enforcement official should have first:
• established that the potentiometric surface measurements are
valid; and
• established that the vertical components of flow have been
accurately depicted and are based on valid data.
1-27
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1-28
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At this point general considerations of ground-water flow may be
estimated. The enforcement officer should construct vertical intercepts
with the rOtentiometric contours for both the potentiometrie surface map
and from flow nets. Once the vertical and horizontal directions of flow
are established (from points of higher head to lower head), it is possible
to estimate where monitoring wells will most likely intercept contaminant
flow in the vertical plane. To consider the placement that will most
effectively intercept contaminant flow, a consideration of hydraulic
conductivity is required.
1.3.2 Seasonal and Temporal Factors: Ground-Water Flow
It is important to note if the owner/operator has identified and
assessed factors that may result in short-term or long-term variations in
ground-water level and flow patterns. Such factors that may impact
ground-water conditions include:
off-site well pumping;
tidal processes or other intermittent natural variations (e.g.,
river stage, etc.);
on-site well pumping;
off-site, on-site construction or changing land use patterns;
deep well injection; and
seasonal variations.
Off-site or on-site well pumping may affect both the rate and
direction of ground-water flow. Municipal, industrial or agricultural
ground-water use may significantly alter or change ground-water flow
patterns and levels over short or long periods of time. Pumpage may be
seasonal or dependent upon other complex water use patterns. The effects
of pumpage thus may reflect time-continuous or discontinuous patterns.
Well water level measurements must have been frequent enough to detect
such water use patterns.
Natural processes such as riverine, estuarine, or marine tidal move-
ment may result in variations of well water levels and/or ground-water
quality. An owner/operator should have documented the effects of such
1-29
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patterns. Seasonal patterns have a significant affect on water table
levels and ground-water flow. Short term recharge patterns may affect
ground-water flow patterns that are markedly different from ground-water
flow patterns that are determined by seasonal averages. An owner/operator
should have gauged such transitional patterns.
Additionally, an owner/operator should have implemented means for
gauging long term effects on water movement that may result from on-site
or off-site construction or changes in land-use patterns. Development
may effect ground-water flow by altering recharge or discharge patterns.
Examples of such changes might include the paving of recharge areas or
damming of waterways.
In reviewing the owner/operator's assessment of ground-water flow
patterns, the enforcement officer should consider whether the owner/
operator's program was sensitive to such seasonal or temporal variations.
An owner/operator should have, in effect, determined not only the location
of water resources but the sources and source patterns that contribute to
or effect ground-water patterns below the regulated site.
1.3.3 Determining Hydraulic Conductivities
In addition to defining the direction of ground-water flow in the
vertical and horizontal direction, the owner/operator must identify areas
of high and low hydraulic conductivity (K) within each formation. Varia-
tions in the hydraulic conductivity of subsurface materials can create
irregularities in ground-water flow paths. Areas of high hydraulic
conductivity represent areas of greater ground-water flow and, if contami-
nants are present, zones of potential migration. Therefore, information
on hydraulic conductivities is required before owner/ operators can make
reasoned decisions regarding well placements.
Enforcement officials should review the owner/operator's hydrogeo-
logic assessment report to ensure that it contains data on the hydraulic
conductivities of the various geologic materials underlying the site.
1-30
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In addition, enforcement officials should review the method the owner/
operator used to derive the conductivity values. It may be beneficial to
use analogy or laboratory methods to corroborate results of field tests;
however, only field methods provide direct information that is adequate
to define the hydraulic conductivity.
Hydraulic conductivity can be determined in the field using either
single or multiple well tests. Single well tests, more commonly referred
to as slug tests, are performed by suddenly adding or removing a slug
(known volume) of water from a well or piezometer and observing the
recovery of the water surface to its original level. Similar results can
be achieved by pressurizing the well casing, depressing the water level,
and suddenly releasing the pressure to simulate removal of water from the
well.
When reviewing information obtained from slug tests, the enforcement
official should consider several criteria. First, slug tests are run on
one well and, as such, the information obtained from single well tests is
limited in scope to the geologic area directly adjacent to the well.
Second, the vertical extent of screening will control the part of the
geologic formation that is being tested during the slug test. That part
of the column above or below the screened interval that has not been
tested during the slug test will not have been adequately tested for
hydraulic conductivity. Third, the methods that the owner/operator used
to collect the information obtained from slug tests should be adequate to
measure accurately parameters such as changing static water (prior to
initiation, during, and following completion of slug test), the amount of
water added to, or removed from, the well, and the elapsed time of
recovery. This is especially important in highly permeable formations
where pressure transducers and high speed recording equipment should be
used. Lastly, the owner/operator's interpretation of the slug test data
should be consistent with the existing geologic information (boring log
1-31
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data). It is, therefore, important that officials examine the owner/
operator's program of slug testing to ensure that enough tests were run
to provide representative measures of hydraulic conductivity and to
document lateral and vertical variation of hydraulic conductivity in the
hydrogeologic subsurface below the site.
Multiple well tests, more commonly referred to as pump tests, are
performed by pumping water from one well and observing the resulting
drawdown in nearby wells. Multiple well tests for hydraulic conductivity
are advantageous because they characterize a greater proportion of the
geologic subsurface and thus provide a greater amount of detail. Multiple
well tests are subject to similar constraints to those listed above for
single well tests, some additional problems that should have been con-
sidered by the owner/operator conducting a multiple well test include:
(1) storage of potentially contaminated water pumped from the well system
and (2) potential effects of ground-water pumping on existing waste
plumes. The enforcement official should closely consider the geologic
constraints that the owner/operator has used to interpret the pump-test
results. Incorrect assumptions regarding geology may translate into
incorrect estimations of hydraulic conductivity.
In reviewing the owner/operator's hydraulic conductivity measure-
ments, the enforcement officer should use the following criteria to
determine the accuracy or completeness of information.
• Values of hydraulic conductivity between wells should not exceed
one order of magnitude difference. If values exceed this
difference the owner/operator may have not provided enough
information to sufficiently define a potential flowpath.
• Hydraulic conductivity for multiple well tests should be
considered the preferred method. They provide more complete
information because they characterize a greater portion of the
subsurface.
• Use of single well tests will require that more individual tests
at different locations to sufficiently define hydraulic
conductivity variation across the site.
1-32
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• Hydraulic conductivity information generally provides average
values for the entire area across a well screen. For more depth
discrete information, well screens will have to be shorter. If
the average hydraulic conductivity for a formation is required,
entire formations may have to be screened.
It is important that hydraulic conductivity measurements define
hydraulic conductivity both in a vertical and horizontal manner across an
owner/operator's regulated site. In assessing the completeness of an
owner/operator's hydraulic conductivity measurements, the enforcement
official should also consider results from the boring program used to
characterize the site geology. Zones of high permeability or fractures
identified from drilling logs should have been considered in the
determination of hydraulic conductivity. Additionally, information from
coring logs can be used to refine the data generated by slug or pump
tests.
1.4 Identification of the Uppermost Aquifer
The owner/operator is required to monitor the uppermost aquifer
beneath the facility. Enforcement officials, therefore, should ensure
that the owner/operator has correctly identified the uppermost aquifer.
Proper identification of the uppermost aquifer is critical to ensure
that monitoring wells are installed in the appropriate stratigraphic
horizon(s).
The uppermost aquifer extends from the water table to the first
confining layer (or ten feet into bedrock) and includes any overlying
perched zones of saturation. The identification of the confining layer
is an essential facet of the definition of uppermost aquifer. There
should be no interconnection, based upon pumping tests, between the
uppermost aquifer and lower aquifers. Consequently, the uppermost
aquifer includes all interconnected water-bearing zones overlying the
confining layer.
When reviewing an owner/operator's hydrologic data and the deci-
sions the owner/operator has made regarding the identification of the
1-33
-------
uppermost aquifer, the enforcement official should keep two important
points in mind. First, the owner/operator should consider the defini-
tion of uppermost aquifer to encompass all water-bearing zones that
serve as pathways for contamination migration including perched zones of
saturation. Saturated formations, even those consisting of relatively
impermeable materials, should be considered as part of the uppermost
aquifer.* Second, the owner/operator should not consider the quality or
use of ground water as a factor in the identification of the geometric
dimensions of the uppermost aquifer. Even though a saturated formation
may not be presently in use or may contain water not suitable for human
consumption, it may act as a pathway for contaminant migration and thus
is subject to monitoring.
In all cases, the obligation to assess any hydraulic interconnections
and the proper definition of the uppermost aquifer rests with the owner/
operator. The owner/operator should be able to prove that confining unit
is of sufficient impermeability to prevent the passage of contaminants to
saturated, stratigraphically lower units.
The following examples illustrate geologic settings wherein hydrau-
lic interconnection must be demonstrated before proper identification of
the uppermost aquifer may be made. The examples are not intended to be
exhaustive in the situations they portray rather they are meant to provide
a sample of geologic settings that result in hydraulic interconnection.
Figure 1-10 illustrates a site that preliminary drill logs indicated
was underlain by a confining layer of unfractured, continuous clay.
(Note: the actual geologic conditions are pictured for purposes of
clarity in the figure.) In order to confirm whether the clay layer was
*Chapter Two describes criteria useful in identifying which portions of
the uppermost aquifer that should be screened. It may not be desirable
for the owner/operator to screen wells in saturated, low permeability
formations even though, technically, these formations are part of the
uppermost aquifer. Other formations may offer a higher probability of
contaminant movement and thus should be selected for monitoring.
1-34
-------
ELEVATION
MSL
- 460'
- 350'
- 300'
- 260'
- 200'
DRILL DRILL
CORE CORE
NO. 3 NO. 5
.'• '••."::;•. .'.• FINE GRAINED SAND •'
------------- CLAY .-_—_-
L 150'
.MEDIUM GRAINED :
SAND ':
FINE GRAINED SAND
;.V-'::VV. •:•.•';; FINE GRAINED
:-.i.-^::::-.:l- SAND
^CRYSTALLINE BASEMENT
WATER
TABLE
I
100
50
1
50
I
100
FIGURE 1-10 EXAMPLE OF HYDRAULIC INTERCONNECTION BETWEEN
WATER - BEARING UNITS
1-35
-------
continuous or discontinuous, the owner/operator conducted a pump test.
A well at drill point No. 5 was screened at the uppermost part of the
water table. Another well at drill point No. 3 was located closeby and
screened below the clay layer. Measurable drawdown was observed in the
upper well when the well below the confining was pumped. This indicated
that the confining unit was not of sufficient impermeability to serve as
a significant boundary to contaminant flow. In this case, the water
bearing unit below the clay layer as well as the formation above the clay
layer are both part of the uppermost aquifer.
In Figure 1-11, the owner/operator drilled test borings through silt
and limestone formations into a sandstone unit. In the initial corings,
no indication of fracturing of the limestone unit was observed. The
owner/operator initially assumed that the limestone unit was dipping at
a moderate slope due to differing levels of contact. However, as illus-
trated by the figure, actual conditions involve fracturing of the lime-
stone formation (additional corings and geophysical studies detected
fracture zones). These fractures represent hydraulic interconnection
between the upper gravelly silt layer and the sandstone formation below
the limestone unit. The uppermost aquifer, therefore, includes the
gravelly silt formation, the limestone formation, and the sandstone
formation.
Figure 1-12 illustrates a situation where perched water zones lie
above the ground-water table. The uppermost aquifer includes the perched
water zones and that part of the sand formation from the top of the water
table to the top of the bedrock.
In Figure 1-13, initial test borings indicated that horizontal sandy
units were underlain by a consolidated well-cemented, impermeable, sand-
stone unit. Initial borings did not indicate the presence of the buried
structural anticline. The owner/operator incorrectly assumed that the
sandstone unit was a confining layer that extended across the subsurface
1-36
-------
300'
200 -i
150 H
100 -
50 -
0 -J
FRACTURED LIMESTONE
WATER
TABLE
i i rw i rTrt i i
100' 50' 0' 50' 100'
FIGURE 1-11. AN EXAMPLE OF HYDRAULIC INTERCONNECTION CAUSED BY FRACTURING
1-37
-------
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1-38
-------
ELEVATION
M.S.L.
p- 700'
300'
-600'
-500
— 400
^-300'
BORE HOLE
BORE HOLE
.••V WASTE UNIT >r.
SANDY ZONE
I DOLOMITE K
(SATURATED)
WATER
TABLE
I
100'
I
50'
I "•
0'
SCALE
50'
100'
FIGURE 1-13. AN EXAMPLE OF AN UNDETECTED, STRUCTURALLY COMPLEX
UPPERMOST AQUIFER
1-39
-------
below the site. A dolomite unit, in contact with the unconsolidated
sandy silts, and directly below the waste unit, is saturated and highly
permeable. Additional investigation including pump tests, borings,
and/or geophysical analysis better defined the subsurface. The uppermost
aquifer, in this case, includes the anticlinal formations.
In Figure 1-14, unconsolidated units are underlain by a consolidated
series of variable, near-shore, shallow marine sediments. The owner/
operator has installed two borings near the waste management unit to
identify the uppermost aquifer. Interpretation of these borings indicate
that the unconsolidated units are underlain by a well cemented limestone
of very low permeability. However, an undetected sandstone unit, that is
laterally continuous with the limestone unit, is highly permeable and
saturated and represents an undetected portion of the uppermost aquifer.
Interpretation of the depositional environment of the limestone unit,
coupled with a knowledge of the local or regional geology should have
been used in addition to other investigatory techniques to establish the
presence of the transitional lateral structural feature and thus properly
define the uppermost aquifer.
A special case, and one that should receive considerable considera-
tion by the enforcement officer, is the situation in which two saturated
units are separated by a confining unit that may be chemically reactive
with the leachate from a regulated unit. Such a situation is illustrated
in Figure 1-15. Two considerations may apply to such a problem:
• Is the subsurface above the confining layer potentially reactive
with the leachate such that it will significantly alter the
leachate characteristics prior to contact with the confining unit?
• Is the reaction with the confining layer going to significantly
affect the hydraulic conductivity of the water-bearing unit?
Another special case that should be considered by the enforcement
official is the possibility that existing wells may provide avenues for
1-40
-------
NEARSHORE
FACIES
OFFSHORE
FACIES
L , I , I . I . I , I . I . I . I
"—r LIMESTONE , ' , I i ' , I
550-
500 -I
150'
I
150'
FIGURE 1-14. AN EXAMPLE OF AN UNDETECTED PORTION OF THE UPPERMOST AQUIFER
(PERMEABLE SANDSTONE UNIT NEAR A COASTAL AREA)
1-41
-------
BORING
MONITORING
WELL
CLUSTER
BORING
Hi^i^i^^SSi^SiS CALCIUM RICH CLAY K - io~7 55^^^-psgS
rn"Vi"Vr»ii1" LI'I'•.::•'iV
»Pi;#nii;-fc:£--frr;:fl;ii;
LEGEND
I WELL AND SCREEN
•
•
10' SCREEN LENGTH
..?.«V»ATER TABLE
FIGURE 1-15
EXAMPLE OF A CONTAMINANT THAT MAY AFFECT THE QUALITY
OF A CONFINING LAYER
1-42
-------
hydraulic communication between hydrogeologic units. This is of special
importance when considering a site where a contaminant plume may have
migrated downgradient such that the plume approaches off-site wells.
Such wells may not have been constructed in a manner sensitive to
problems of cross-contamination between aquifers (see Chapter Four).
In such an instance, the off-site wells may have to be plugged and
replaced with appropriately designed wells.
1-43
-------
CHAPTER TWO
PLACEMENT OF DETECTION MONITORING WELLS
The purpose of this chapter is to examine criteria the enforcement
official should use in deciding if the owner/operator has made proper
decisions regarding number and location of detection monitoring wells.
In evaluating the design of an owner/operator's detection monitoring
system, the enforcement official must examine the placement of upgradient
and downgradient monitoring wells relative to hazardous waste management
units, the spacing between wells, and the depths at which wells are
screened. The minimum number of monitoring wells an owner/operator may
install in a detection monitoring system is four—one upgradient well and
three downgradient wells. Typically, site hydrogeology is too complex
for the minimum number of wells to prove adequate in achieving the
performance objectives of a detection monitoring system.
Chapter One described the level of hydrogeologic characterization
that owner/operators should conduct at their sites. Collection and
analysis of this data is crucial to making proper decisions regarding
the placement of wells and well clusters and the selection of screened
intervals for individual wells. It is likely that the enforcement
! official may confront situations where the owner/operator has collected
i
; little or no site hydrogeologic information or has relied exclusively
\ on regional data to design a monitoring system. In this situation, the
1 enforcement official should question the decisions the owner/operator has
i made regarding well placement and screen depths and should require the
, owner/operator to collect additional site information.
1 Upgradient monitoring wells provide background ground-water quality
t
data in the uppermost aquifer. Upgradient wells should be (1) located
beyond the upgradient extent of contamination from the hazardous
waste management unit so that they reflect background water quality,
2-1
-------
(2) screened at the same stratigraphic horizon(s) as the downgradient
wells to ensure comparability of data, and (3) of sufficient number to
account for heterogeneity in background ground-water quality.
Downgradient wells must be located, screened, and sufficiently
numerous to provide a high level of certainty that releases of hazardous
waste or hazardous waste constituents from the hazardous waste management
unit(s) to the uppermost aquifer will be immediately detected. Deter-
mination of the appropriate number of wells to be included in a detection
monitoring system hinges on the horizontal spacing between well locations
and the vertical sampling interval of individual wells. Downgradient
monitoring wells must be located at the edge of the hazardous waste
management units. Distance between wells is chiefly a function of
spatial heterogeneity of a site. The consideration of site specific
conditions to evaluate well spacing is described in Section 2.1. The
depth interval(s) over which downgradient monitoring wells should be
screened is a function of (1) geologic factors influencing the potential
contaminant pathways of migration to the uppermost aquifer, (2) chemical
characteristics of the hazardous waste controlling its likely movement
and distribution in the aquifer, and (3) hydrologic factors likely to
have an impact on contaminant movement. The consideration of these
factors in evaluating the design of detection monitoring systems is
described in section 2.2.
It is important to keep in mind that a properly designed detection
monitoring system will provide a high level of assurance that contaminant
leaks will be immediately detected. RCRA does not, however, require
complete certainty that all leaks be immediately detected. A sufficient
number of detection monitoring wells screened at the proper depths must
be installed by the owner/operator to ensure that his ground-water
monitoring system guarantees an acceptably high level of certainty that
contaminant leakage will be immediately detected. Although every
2-2
-------
detection monitoring system must ultimately be judged against site
' specific conditions, there are a number of criteria that enforcement
officials can apply to ensure that detection monitoring systems satisfy
' the RCRA regulatory requirements. This chapter examines those criteria
1 and provides examples on how enforcement officials can apply criteria in
various hydrologic situations.
i 2.1 Placement of Downgradient Detection Monitoring Wells
!
1 This section describes criteria the enforcement official may use to
i
i evaluate decisions the owner/operator has made regarding placement of
downgradient wells. Specifically, Section 2.1.1 describes criteria for
evaluating the location of downgradient wells relative to waste manage-
ment areas. Section 2.1.2 describes criteria for evaluating horizontal
spacing between downgradient detection monitoring wells. Section 2.1.3
describes criteria for evaluating the depth of wells and vertical
sampling intervals.
2.1.1 Location of Wells Relative to Waste Management Areas
In order to be able to immediately detect leaks should they occur,
the owner/operator should install downgradient detection monitoring wells
immediately adjacent to hazardous waste management units. In a practical
sense, this means the owner/operator should install detection monitoring
wells as close as physically possible to the edge of hazardous waste
management unit(s). The two drawings in Figure 2-1 (A and B) illustrate
the concept of the placement of wells immediately adjacent to hazardous
waste management unit(s). Note how the placement of wells relative to
the units shifts as a function of the direction of ground-water flow.
In geological settings exhibiting interbedded unconsolidated sands,
silts, and clays (e.g., alluvial facies) where the water table is deep-
seated, the lateral component of contaminant migration may carry it
beyond the ground-water monitoring system before contaminants reach
2-3
-------
GROUND-WATER
FLOW
HAZARDOUS
WASTE MANAGEMENT
AREA A
-1
1
|
1
L
LIMIT OF WASTE
MANAGEMENT AREA
1
1
1
1
1
1
HAZARDOUS WASTE
MANAGEMENT AREA B
_ ^ -^ ^~ ^« — —
HAZARDOUS WASTE
MANAGEMENT
AREA A
TO)
fl>
LIMIT OF WASTE
MANAGEMENT AREA
GROUND-WATER
FLOW
1
I
1
1
HAZARDOUS WASTE
MANAGEMENT AREAS
LEGEND
MONITORING WELL
FIGURE 2-1. DOWNGRADIENT WELLS IMMEDIATELY ADJACENT TO
HAZARDOUS WASTE MANAGEMENT LIMITS
2-4
-------
ground water, and therefore beyond detection. The owner/operators could
institute a program of vadose zone monitoring as a supplement to the
ground-water monitoring program in such cases to provide immediate
detection of any release(s) from the hazardous waste management area.
Volatile organics which escape to the vadose zone, for instance, may be
detected and characterized through soil gas analysis.
2.1.2 Horizontal Spacing Between Downgradient Monitoring Wells
An owner/operator's downgradient detection monitoring wells must be
spaced closely enough together to assure that the ground-water monitoring
system guarantees an acceptably high level of certainty that contaminant
leakage will be immediately detected. The judgment as to whether the
owner/operator has spaced detection monitoring wells close enough
together does, of course, require analysis of site-specific conditions.
Table 2-1 illustrates factors the enforcement official may use to decide
if the owner/operator has made proper spacing decisions. These factors
cover a variety of physical and operational aspects relating to the
facility including hydrogeologic setting, facility design, waste
characteristics and climate. The enforcement official should consider
all factors described in Table 2-1 when evaluating well spacing.
i The Agency has selected 150 feet as the point of departure from
, which well spacing may be compressed or expanded. By using the 150-foot
: spacing number as a point of departure and evaluating site specific
1 factors, the enforcement official should be able to judge the ability of
i
i the owner/operator's monitoring system to immediately detect contaminant
, leakage. It should be noted that the 150-foot number is not one that
enforcement officials should dogmatically apply. Site specific condi-
1 tions should always drive decisions. In some cases, closer spacing is
needed over all or over part of the site. In others, a wider spacing
is adequate. In any event, the enforcement official is ultimately
responsible for ensuring that well spacings are adequate given site
2-5
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conditions. Final determination of adequate spacing will often come
after comprehensive technical negotiations with the owner/operator in
which each factor relating to spacing is evaluated and applied to spacing
decisions. The enforcement official should, in these cases, remember
that the 150-foot number is a starting point for negotiation and that the
enforcement official is well within his authority to insist on closer
spacing or to allow wider spacing. The following examples illustrate how
site-specific factors as described in Table 2-1 may affect well spacing.
Figure 2-2 illustrates a facility which contains both a landfill and
a surface impoundment. In this example, site geology is simple and
homogeneous. The landfill has received very little liquid waste and its
design is well documented. The surface impoundment contains a large
volume of liquid waste. Monitoring wells around the landfill are spaced
225 feet apart because of simple and homogeneous site geology. Monitor-
ing wells around the surface impoundment are spaced 75 feet apart since
there exists a greater potential for the generation of narrow contaminant
plumes through holes in the liner propelled by the intrinsic head of the
liquid waste in the impoundment.
't The two drawings in Figure 2-3 illustrate well placement based upon
surficial stratigraphic complexity. In drawing A, the landfill is com-
i
i pletely situated on homogenous geology allowing the average well spacing
to prevail. Drawing B shows a facility that is situated over heterogenous
| geology where well spacings need to be altered to account for changes in
1 lithology. Monitoring well spacing in the sand and gravel formation
I
i should be closer than that in the clay-silt formation. The potential for
. the escape from detection of more rapidly migrating narrow plumes,
| especially through gravel seams, is higher in sand and gravel formations
than in clay-silt formations which are characterized by lower hydraulic
conductivities and higher diffusivities. Figure 2-3 illustrates how well
spacing should change to reflect the different lithologic units. The
monitoring wells in the clay and silt are spaced at 175 feet apart.
2-7
-------
GROUND-WATER
FLOW
BOUNDARY OF
WASTE
MANAGEMENT
UNIT
SURFACE
IMPOUNDMENT
GRAVELY SANDY TILL
GRAVELY
SAND
FIGURE 2-2. WELL SPACING BASED UPON WASTE CHARACTER
2-8
-------
GROUND-WATER
f FLOW
CLAY
SILTY
SAND
LANDFILL
WASTE MANAGEMENT
AREA
150'
GROUND-WATER
• FLOW
T
LEGEND
• MONITORING WELLS
O BACKGROUND WELLS
l\. PROPERTY LINE
FIGURE 2-3. WELL SPACING BASED UPON SITE GEOLOGY
2-9
-------
Figure 2-4 illustrates a facility where a landfill is situated on
a small hilltop in sandy-silt overlying glacial till. The ground-water
movement at the landfill is radial in all directions due to the induced
hydraulic gradients caused by the mound. The site characterization data
indicates more permeable fill on the edge of the facility. The swamp to
the southeast is recharged from the landfill area. Since the discharge
of the local ground water is into the swamp, closer well spacing is
necessary to monitor potential discharge in that area. Note that since
contaminants may move from this site in any radial direction that
detection monitoring wells should ring the unit.
Figure 2-5 illustrates a situation where permeabilities are low
-4
(10 cm/sec) except in one area of the site which has higher permea-
bility (10 cm/sec) which may be indicative of a preferential flow
pathway. Closer well spacing is required in the area of preferential
flow.
Figure 2-6 illustrates an unlined surface impoundment located on
regularly-spaced nearly vertical fractures in consolidated siltstone.
The wells should be located to intercept major fractures. To ensure
that all levels are monitored, additional wells are located downgradient
in the low permeable rock matrix. The wells (Nos. 1 through 6) appearing
to be upgradient of the facility are actually downgradient due to the
orientation of the fractures.
Figure 2-7 illustrates two waste disposal units on the same facility.
Waste Unit A is an impoundment that is 15 years old, waste Unit B is a
5-year old landfill. The site is located on simple homogenous geology
-3 -4
with a moderate permeability of 10 to 10 cm/sec. Because of the age
of Unit A and the presence of surface liquids, there exists a greater
probability of a contaminant release; therefore wells need to be much
closer together than the newer Waste Unit B.
2-10
-------
GROUND-WATER
FLOW
LEGEND
MONITORING WELLS
BACKGROUND WELLS
PROPERTY LINE
FIGURE 2-4. WELL PLACEMENT BASED UPON LOCALLY INUNDATED AREAS
2-11
-------
GROUND-WATER
FLOW
O LIMITOFQ
WASTE MANAGEMENT
AREA
GRAVELY
SILTY-
SAND
ADDITIONAL
WELLS
NEEDED
HERE
LEGEND
*
PL
BACKGROUND WELLS
MONITORING WELLS
ADDITIONAL WELLS
PROPERTY LINE
FIGURE 2-5. WELL PLACEMENT BASED UPON A CHANGE OF
PREFERENTIAL ROUTES OF MIGRATION
2-12
-------
GROUND-WATER
FLOW
FACTORY
SURFACE
IMPOUNDMENT
SILTSTONE
LEGEND
o
•
n.
BACKGROUND WELL
MONITORING WELL
PROPERTY LINE
FIGURE 2-6. WELL PLACEMENT BASED UPON STRUCTURAL FRACTURING
2-13
-------
GROUND-WATER
FLOW
SURFACE
IMPOUNDMENT
FIGURE 2-7. WELL PLACEMENT BASED UPON AGE AND WASTE CHARACTER
2-14
-------
2.2 Depth of Veils/Vertical Sampling Interval(s)
Site-specific hydrogeological data generated by the owner/operator
during the site characterization is indispensable not only to the
determination of horizontal well spacing, but to the identification of
the vertical sampling interval(s) as well. Proper selection of the
vertical sampling interval provides the third dimension to the detection
monitoring of potential contaminant pathways to the uppermost aquifer.
Proper selection of the vertical sampling interval enables the owner/
operator to design a detection monitoring system capable of immediately
detecting a release from the hazardous waste management area with a high
level of certainty. It is essential, therefore, that the owner/operator's
decisions regarding vertical sampling intervals are based upon site
characterization data which identify both the depth and thickness of the
stratigraphic horizon(s) most likely to serve as contaminant pathways.
There are several guidelines or criteria that the enforcement official
should follow in evaluating owner/operator decisions. A discussion of
these guidelines follows.
2.2.1 Depth of Wells
The owner/operator should know from the site characterization which
stratigraphic horizons represent potential contaminant migration pathways
and should screen monitoring wells at the appropriate horizon(s) to ensure
immediate detection of a release. It is extremely important to screen
upgradient and downgradient wells at the same stratigraphic horizon(s) to
obtain comparable ground-water quality data. The determination of the
depth to a potential contaminant migration pathway may be made from
soil/rock cores, supplemented by geophysical and available regional
hydrogeological data.
2.2.2 Thickness of the Vertical Sampling Interval(s)
Determination of the appropriate thickness of the vertical sampling
interval(s) is a natural extension of the depth selection. The owner/
operator should make the decision on the basis of site characterization
2-15
-------
data. Sources could include isopach maps of highly permeable strata, and
stereographs of local geologic structures generated with soil/rock cores,
geophysical and regional geological data.
In most cases, screen lengths should be no longer than ten feet.
Shorter screens promote better resolution of contaminant concentrations
than longer ones, which is a principal goal of detection monitoring. At
sites where the vertical sampling interval is greater than ten feet, the
owner/operator should install a well cluster at each sampling location.
A well cluster is a number of wells grouped closely togetner often
screened at different stratigraphic horizons. The greater the extent of
the vertical sampling interval, the more wells the owner/operator should
place in a cluster.
It is important to remember that the vertical sampling interval is
not necessarily synonymous with aquifer thickness. In other words, the
owner/operator may select a vertical sampling interval which represents a
fraction of the thickness of the uppermost aquifer. The selection should
be made on the basis of site characterization data. A sufficiently
detailed site characterization may therefore reduce the need for the
owner/operator to install more speculative wells by identifying, with a
reasonable degree of certainty, the preferential flow paths from the
hazardous waste management area to the uppermost aquifer. The owner/
operator thus tailors the selection of the vertical sampling interval to
site-specific conditions.
There are situations where the owner/operator should have multiple
wells at a sampling location and others where typically one well is
sufficient. They are summarized in Table 2-2. Generally, the presence
of immiscibles in a thick, complex saturated zone of the uppermost
aquifer should prompt the owner/operator to use well clusters. Con-
versely, single phase contaminated ground water and a thin saturated zone
within the uppermost aquifer, or isotropic hydrologic properties reduce
the need for multiple wells at each sampling location. Where seasonal
2-16
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TABLE 2-2
FACTORS AFFECTING NUMER OF WELLS PER LOCATION (CLUSTERS)
One Well per Sampling Location
No "sinkers" or "floaters"
(immiscible liquid phases;)
see glossary for more detail)
Thin flow zone
(relates to 10-foot screen
exception)
Homogenous uppermost aquifer;
simple geology
More Than One Well Per Sampling
Presence of sinkers or
floaters
Hetergeneous uppermost aquifer;
complicated geology
- multiple, interconnected
aquifers
- variable lithology
- perched water table
- discontinuous structures
Discrete fracture zones
2-17
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fluctuation of the water table occurs and the owner/operator intends to
sample for light phase iramiscibles floating on it, the owner/operator
should use screens long enough to always intercept the water table and
floaters instead of installing multiple wells.
When the site characterization data indicate the presence of
different but hydraulically interconnected strata, some of the wells
should be screened with the bottom of the screens placed at the interface
between the strata. Also, the owner/operator should have delineated
through site characterization (e.g., flow net analysis) those flow zones
in the aquifer(s) in which there is higher potential for contaminant
movement. The owner/operator should install enough wells to ensure
continuous screening in these zones. As above, these screens should not
be longer than ten feet in flow zones in which a higher potential for
contaminant movement exists.
The number of wells screened at different depths that an
owner/operator should install at each sampling location increases with
site complexity. Site factors which affect the number of wells that
should be installed at each location are described in Table 2-2. The
following examples illustrate how enforcement officials can use the
factors discussed above to make decisions on the vertical spacing (depth)
of wells and well screens.
Figure 2-8 illustrates a site where the owner/operator has adopted
the use of geophysical techniques and soil gas analysis in a program of
detection monitoring. The owner/operator's landfill is situated in
unconsolidated silty sand and primarily contains organic wastes. The
detection monitoring system in place at this facility provides for an
integrated program of direct monitoring (e.g., wells), surface electro-
magnetic conductivity, surface resistivity, and organic vapor/soil gas
analysis. (Appendix C provides information on geophysical techniques and
soil/gas analysis.) Wells are located at 300-foot intervals. Geophysical
2-18
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measurements and soil gas analysis supplement the collection of monitoring
well data. Although the spacing between the wells has been expanded, the
collection of additional data through various complementary techniques
allows for adequate detection of leakage at this particular site. It
should be noted, however, that the use of geophysical techniques and soil
gas analysis is not a substitute for the installation of monitoring wells.
There are, in fact, many situations where these methods cannot be used.
in any event, the applications of these methods should not result in a
drastic expansion of well spacing in a detection monitoring system.
Figure 2-9 is a cross section of a landfill site situated on a thin
silty sand unit having a lower boundary of thick impermeable clay. Since
the silty sand layer is the major matrix affecting ground-water flow, a
double-well cluster is necessary to ensure the unit is screened at the
water table and interface of the lowest confining unit. The screen at
the water table must be situated and of the proper length to account for
seasonal fluctuations in the water table.
Figure 2-10 shows the potential relationship between a landfill, its
hydrology, and well depth. The facility is located on a thick uniform
aquifer near its discharge point. Hydrological studies indicate an
upward flow component between the landfill and the aquifer discharge
area. Heavy and light imraiscibles are expected from the facility. From
this scenario, leachate is expected to move downward thereby establishing
the need for only double-well clusters to detect for light and heavy
phase materials. (Note: This diagram shows only one well cluster.) The
shallow well should be screened at the water table to detect the presence
of light phase immiscibles. The lower well should be screened where the
heavier phase materials would be expected.
Figure 2-11 illustrates a landfill situated on silt underlain by
discretely fractured, hydraulically connected rock. A three-well cluster
is needed to adequately monitor ground-water conditions. The first well
2-20
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MONITORING
WELL
CLUSTER
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-9. WELL DEPTH DETERMINATION BASED UPON FLOW-NET ANALYSIS
2-21
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WELL CLUSTER
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BACKGROUND
WELL CLUSTER
~ £>£ I? FLOW OF Kr-:
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GROUND-WATER HKHH3S-3 -K I-I-3£H>»:
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LEGEND
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_ _ WATER TABLE
FIGURE 2-11. WELL PLACEMENT BASED UPON CHANGES IN GEOLOGY
2-23
-------
(1A) is screened at the water table to detect light phase iramiscibles.
The 15-foot screen accounts for a five foot variation in the water
table. The second well (IB) is screened for ten feet at the fractured
rock interface to monitor ground-water movement in the fractures. The
third well (1C) is screened at the interface of the fractured bedrock
layer to allow for detection of contaminant movement to the first
confining unit.
Figure 2-12 illustrates a landfill situated on silt underlain by
sand and gravel, weathered shale and solid bedrock. The first 50 feet of
the shale is weathered. A cluster of four wells is necessary to monitor
the ground water under this facility. The first well (1A) monitors the
water table. The next two wells monitor the silt (IB) sand and gravel
(1C) layers which are the major water bearing units. The fourth well
monitors the last ten feet of the shale layer. These last two wells are
primarily for the detection of heavy phase immiscibles.
Figure 2-13 illustrates a landfill situated on porous sandstone
underlain by a 100-foot thick claystone unit, a coal aquifer and
bedrock. The sandstone is not hydraulically connected to the confined
coal aquifer. The double-well cluster (1A and IB) should include well
screens in the sandstone and in the top of the claystone. since the
claystone has low permeability, it is not necessary to monitor the
coal-claystone interface. The separate confined coal aquifer does not
require monitoring since slug test data from Well 2 establishes that it
is not hydraulically connected to the upper layers.
2.3 Placement of Upgradient (Background) Monitoring Wells
Since the downgradient wells must be properly situated to detect
contaminant discharges into the uppermost aquifer, the upgradient wells
should be located and constructed to provide representative samples of
ground water in the same aquifer with which the downgradient samples can
be compared.
2-24
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MONITORING
WELL
CLUSTER
IDBC A
BACKGROUND
WELL
CLUSTER
GROUND
WATER FLOW
DIRECTION
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-------
BACKGROUND
WELL
CLUSTER
MONITORING
WELL
CLUSTER
MONITORING
WELL
LEGEND
j WELL AND SCREEN
10' SCREEN LENGTH
.7... WATER TABLE
FIGURE 2-13. WELL DEPTH BASED UPON POSSIBLE HYDRAULIC CONNECTION
2-26
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There are three questions the enforcement official should ask as he
reviews the decisions the owner/operator has made regarding the placement
of his background monitoring wells:
• Has the owner/operator located background wells far enough away
from waste management areas to prevent contamination from the
facility?
• Has the owner/operator installed enough wells, screened at
appropriate depths, to adequately account for spatial variability
in background water quality?
• Has the owner/operator used well clusters at sampling locations
so that comparisons of background data with downgradient data are
made within the same hydrologic unit?
The owner/operator must install background wells so that the ground-
water samples taken from these wells cannot be affected by contaminant
discharge from the facility. Usually, this is accomplished by locating
the background wells far enough upgradient from waste management units to
avoid contamination by the facility. For most sites, upgradient areas
which are not likely to be affected by the facility can be readily
identified from examination of water level data. However, in some
special cases, locating the upgradient wells to avoid contamination is
complicated.
The minimum number of wells the owner/operator may install is one.
However, a facility that uses only one well for background sampling may
not be able to account for spatial variability in water quality. It is,
in fact, a very unusual circumstance in which only one background well
is adequate such as a facility in a completely homogeneous uppermost
aquifer. The owner/operator who makes comparisons of background and
downgradient monitoring well results with data from only one background
well increases the risk of false indication of contamination. In most
cases, the owner/operator should install at least four background moni-
toring wells in the uppermost aquifer to account for spatial variability
in background water quality data.
2-27
-------
The owner/operator should also install enough background monitoring
wells to allow for depth-discrete comparisons of water quality. This
means simply that for downgradient wells completed in a particular
geologic formation and at a particular depth, the owner/operator should
install corresponding wells at the upgradient sampling locations so that
the data can be compared on a depth-discrete basis. Figure 2-14
illustrates this concept.
It is not usually acceptable for an owner/operator to install back-
ground monitoring wells that are screened over the entire thickness of
the uppermost aquifer. Screening the entire thickness of the uppermost
aquifer will not allow the owner/operator to obtain depth-discrete water
quality data. Instead, what the owner/operator will obtain is average
water quality data for the entire thickness of the uppermost aquifer. In
order to obtain depth-discrete water quality data, the owner/operator
should use well screens no longer than ten feet.
In order to establish background ground-water quality, it is
necessary to properly identify ground-water flow direction and place
wells upgradient to the waste management area. There are several
geological and hydrological situations for which determination of the
upgradient location is often difficult; further site-specific examination
is necessary to properly locate background wells:
1. Waste management areas above water table mounds.
2. Waste management areas located above aquifers in which
ground-water flow directions change seasonally.
3. Waste management areas located close to a property boundary that
is in the upgradient direction.
4. Waste facilities containing significant amounts of immiscible
contaminants with densities greater than or less than water.
5. Waste management facilities located in areas where nearby
surface water can influence ground-water levels (e.g., river
floodplains).
2-28
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MONITORING
WELL
CLUSTER
BACKGROUND
WELL
CLUSTER
LEGEND
WELL AND SCREEN
10' SCREEN LENGTH
,,.'....WATER TABLE
FIGURE 2-14. PLACEMENT OF BACKGROUND WELLS
2-29
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6. Waste management facilities located near production for
intermittently-used wells.
1. Waste management facilities located in Karst areas or faulted
areas where fault zones may modify flow.
2-30
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CHAPTER THREE
MONITORING WELL DESIGN AND CONSTRUCTION
The purpose of this chapter is to examine important aspects of RCRA
monitoring well design and construction. Included in this chapter are
discussions on the following topics:
• drilling methods for installing wells (Section 3.1);
• monitoring well construction materials (Section 3.2);
• design of well intakes (Section 3.3);
• development of wells (Section 3.4);
• documentation of well construction activity (Section 3.5);
• specialized well design (Section 3.6); and
• replacement of existing wells (Section 3.7).
3.1 Drilling Methods
A variety of well drilling methods are available for the purpose of
installing ground-water monitoring wells. Of utmost importance is that
the drilling method the owner/operator uses will minimize the disturbance
of subsurface materials and will not cause contamination of the subsurface
and ground-water. Table 3-1 illustrates the drilling methods the owner/
operator should use in installing wells. The selection of the actual
drilling method that an owner/operator should use at a particular site
is, of course, a function of site-specific geologic conditions. Table 3-1
illustrates how geologic conditions will influence the choice of drilling
method the owner/operator shoud use. The following sections discuss each
drilling method and its applicability to the installation of RCRA moni-
toring wells. It is important to note that regardless of the drilling
method the owner/operator selects, the owner/operator should steam-clean
drilling equipment before use and between borehole locations to prevent
cross contamination of wells.
3-1
-------
TABLE 3-1
DRILLING METHODS FOR
VARIOUS TYPES OF GEOLOGIC SETTINGS
Drilling Methods
Geologic Environment
Air
Rotary
Water
Rotary
Cable
Tool
Hollow-Stem
Continuous
Auger
Solid-Stem
Continuous
Auger*
Glaciated or unconsolidated
materials less than 150 feet
deep
Glaciated or unconsolidated
materials greater than 150 feet
deep
Consolidated rock formations
less than 500 feet deep (minimal
or no fractured formations)
Consolidated rock formations
less than 500 feet deep (highly
fractured formations)
Consolidated rock formations
more than 500 feet deep (minimal
formations)
Consolidated rock formations
more than 500 feet deep (highly
fractured formations)
*Above water table.
NOTES:
1 = First choice
2 = Second choice
3 = Third choice
3-2
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3.1.1 Hollow-Stem Continuous-Flight Auger
The hollow-stem continuous-flight auger rig is among the most
frequently employed drill rigs for the construction of monitoring wells
in unconsolidated materials. The rigs are generally mobile, fast, and
inexpensive to operate. No drilling fluids are used and disturbance to
the geologic materials penetrated is minimal. However, augers can only
be used in unconsolidated rock and most rigs are limited to drilling to
approximately 150 feet. In formations where the borehole will not stand
open, the well is constructed inside the hollow-stem augers prior to
their removal from the ground, six-inch inside diameter hollow-stem
augers are available for this purpose. The diameter of the well that
can be constructed with this type of drill rig is limited to four inches
or less. The use of hoilow-stem auger drilling in heaving sand environ-
ments also presents some difficulties for the drilling crew. However,
with care and the use of proper drilling procedures, this difficulty can
be overcome.
3.1.2 Solid-Stem Continuous-Flight Auger
The use of solid-stem continuous-flight auger drilling techniques
for monitoring well construction is limited to fine-grained unconsoli-
dated materials that will maintain an open borehole or in consolidated
sediments. The method is similar to the hollow-stem continuous augers
except that the augers must be removed from the ground to allow insertion
of the well casing and screen. This method is also limited to a depth of
up to 150 feet. In profiles consisting of less competent materials,
solid-stem auger drilling can be utilized to limited depths; however,
caving of the borehole does present a problem making installation of the
casing difficult to impossible. Another restriction of the solid-stem
auger is the use below the water table. Again, maintaining the integrity
of the borehole in the saturated zone is sometimes difficult, especially
in environments of poorly consolidated sediments. Solid-stem auger
drilling does not lend itself to in-place well construction as with the
3-3
-------
hollow-stem auger. Collection of soil or formation samples is impracti-
cal, and therefore, accurately portraying the subsurface profile at the
site is difficult. Solid stem augers thus cannot be used in the boring
program for site characterization.
3.1.3 Cable Tool
The cable tool type of rig is relatively slow but offers many
advantages that make it the useful for monitoring well construction in
relatively shallow consolidated formations and unconsolidated formations.
The method allows for the collection of excellent formation samples and
detection of even relatively fine grained permeable zones. The installa-
tion of a steel casing as drilling progresses also provides an excellent
temporary host for the construction of a monitoring well once the desired
depth is reached.
Small amounts of water must be added to the hole as drilling
progresses until the water table is encountered. The owner/operator
should only use water that cannot itself contaminate formation water.
A minimum six-inch diameter drive pipe should be used to facilitate the
placement of the well casing, screen, and gravel pack, and a minimum five
foot long seal prior to beginning the removal of the drive pipe. The
placement of the seal in the drive pipe prior to pulling will assist in
holding the gravel pack, casing, and screen in place. The drive pipe
should be pulled while the sealant is still fluid and capable of flowing
outward to fill the annular space vacated by the drive pipe. The drive
pipe also should be pulled in sections and additional sealant added to
ensure that a satisfactory seal is obtained. For the most part, cable
tool rigs have been replaced by rotary rigs in most of the United States.
Therefore, cable tool rigs may not be readily available in many regions.
3.1.4 Air Rotary
Rotary drilling methods operate on the principle of circulating
either a fluid or air to remove the drill cuttings and maintain an open
3-4
-------
hole as drilling progresses. The different types of rotary drilling are
named according to the type of fluid and the direction of fluid flow.
Air rotary drilling forces air down the drill pipe and back up the bore
hole to remove the drill cuttings. The use of air rotary drilling
techniques is best suited for use in hard rock formations. In soft
unconsolidated formations casing is driven to keep the formations from
caving.
Air rotary drilling can be used for constructing monitoring wells
without affecting the quality of water from monitoring wells in hard rock
formations with minimum unconsolidated overburden. The successful
construction of monitoring wells using this drilling technique is
dependent on the ability of the bore hole to stand open after the air
circulation ceases. The air from the compressor on the rig should be
filtered to ensure that oil from the compressor is not introduced into
the geologic system to be monitored. Foam or joint compounds for the
drill rods should not be used with air rotary drilling because of the
potential for introduction of contaminants into the hydrogeologic
system. The use of air rotary drilling techniques should not be used
in highly polluted or hazardous environments. Contaminated solids and
water that are blown out of the hole are difficult to contain and may
adversely affect the drill crew and observers. Conversely, air rotary
drilling techniques have actually improved safety conditions where
contamination is due to volatile constituents in some instances.
3.1.5 Water Rotary
Water rotary drilling introduces water into the borehole by way
of the drill pipe, circulates water back up the hole and removes drill
cuttings. Great care must be taken to ensure that water used in the
drilling process does not contain contaminants. If the owner/operator
uses water rotary drilling to install wells, the owner/operator should
analyze drilling water to ensure it is contaminant free.
3-5
-------
There are problems associated with the use of water rotary drill-
ing. The recognition of water-bearing zones is hampered by the addition
of water into the system. Also, in poorly consolidated sediments, the
drillers may have a problem with caving of the borehole prior to instal-
lation of the screen and casing. In highly fractured terrains, it may
also be hard to maintain water circulation.
3.1.6 Mud Rotary
Mud rotary drilling techniques use various types of muds as the
medium which is introduced into the borehole. The mud circulates back
up the hole during drilling, carrying away drill cuttings much as air and
water rotary methods. Muds provide the additional benefit of stabilizing
the hole, especially in deep-seated highly saline formations.
There are several types of muds available at present primarily
bentonite, barium, sulfate, and organic polymer types. While there are
hydrogeologic conditions under which mud rotary drilling is the best
option (i.e., deep-seated highly saline formations), the enforcement
official should make certain that the mud(s) utilized affect neither
the chemistry of ground-water samples nor the operation of the well and
hence the assessment of aquifer characteristics. For example:
• Bentonite muds tighten the formation around the well thereby
compromising estimates of well recovery. Bentonite may also
affect local ground-water pH.
• Barium sulfate muds introduce barium to the ground water. Barium
is a RCRA extraction procedure toxicity parameter and Clean Water
Act priority pollutant.
• Organic polymers and compounds provide an environment for
bacterial growth which, in turn, reduces the reliability of
sampling results.
3.2 Monitoring Well Construction Materials
The enforcement official must ensure that the owner/operator uses
well construction materials that are durable enough to resist chemical
3-6
-------
I
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1 Figure 3-1.
and physical degradation and do not interfere with the quality of
ground-water samples. Specific well components that are of concern
include well casings, well screens, filter packs, and annular seals.
Figure 3-1 is a diagram of a general cross section of a ground-water
monitoring well. The following sections describe various materials the
owner/operator should use in constructing the well as illustrated in
3.2.1 Well Casings and Well Screen
A variety of construction materials have been used for the casings
and well screens of including, teflon*, steel (stainless, black, galva-
nized), PVC, polyethylene, epoxy biphenol, and polypropylene. Many of
these materials, however, may affect the quality of ground-water samples
and may not have the long-term structural characteristics required for
RCRA monitoring wells. For examples, steel casing deteriorates in
corrosive environments; PVC deteriorates when in contact with ketones,
esters, and aromatic hydrocarbons; polyethylene deteriorates in contact
with aromatic and halogenated hydrocarbons; and polypropylene deteriorates
in contact with oxidizing acids, aliphatic hydrocarbons, and aromatic
hydrocarbons. In addition, steel, PVC, polyethylene, and polypropylene
may adsorb and leach constituents which may affect the quality of
ground-water samples.
In constructing wells, the owner/operator should use teflon,
stainless steel 316, or other proven chemically and physically stable
materials for well screens and for those portions of the well casing in
the saturated zone. Other noninert materials such as steel, PVC, poly-
ethylene and polypropylene may be used as well casing above the saturated
*The use of the term "teflon" in this report by U.S. EPA is purely as a
generic expression for polytetrafluoroethylene (PTFE) materials and in
no way is meant to serve as an endorsement of PTFE products under the
U.S. Trademark name of E.I. DuPont DeNemours and Company.
3-7
-------
STEEL PROTECTOR CAP WITH LOCKS
WELL CAP
CONCRETE CAP (EXPANDING CEMENT)
CEMENT AND SODIUM
BENTONITE MIXTURE
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BORE HOLE DIAMETER = 10"
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zone. Figure 3-2 illustrates the concept of such a composite well.
There are two reasons why owner/operators should use teflon or stainless
steel 316 as screens and as well casing materials.
• Teflon and stainless steel 316 are more highly resistant to
corrosion from a wide variety of chemical species likely to be
encountered in the field than other well casing materials
currently in use, e.g., polyvinyl chloride, stainless steel 304.
This trait is important because it indicates that wells con-
structed of teflon or stainless steel 316 casings will retain
their structural integrity over the long term better than those
constructed of other materials. Long term structural integrity,
i.e., 30 or more years, is essential to the collection of
unbiased ground-water samples over the active life of the
facility.
• Owner/operators of facilities whose Part B or post-closure per-
mit application has been called are required under 270.14(c)(4)
to analyze any plume(s) for Appendix VIII constituents. The
remainder of facilities must monitor for Appendix VII constit-
uents. Both appendices include organic constituents. Well
construction materials should not bias the collection and
analysis of low concentrations of these organic constituents
by reacting with the ground-water samples. Current research
suggests that teflon and stainless steel 316 do not sorb or
leach trace organics constituents to the degree that other
materials do, e.g., organic polymers, galvanized steel.
Plastic pipe sections must be flush threaded or have the ability to
be connected by another mechanical method which will not introduce
contaminants such as glue or solvents into the well. All well casings
and screens should be steam cleaned prior to emplacement to ensure that
all oils, greases, and waxes have been removed.
The owner/operator should normally use well casing with either a
two-inch or four-inch interior diameter. Larger casing diameters,
however, may be necessary where dedicated purging or sampling equipment
is used or where the well is finished in a deep formation. In addition,
for those wells screened at an interface between relatively tight and
porous formations and where the accumulation or bottom flow of dense
3-9
-------
V
t
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GROUND SURFACE
PVC OR OTHER NONINERT MATERIAL
ABOVE SATURATED ZONE
POTENTIOMETRIC SURFACE
INERT MATERIALS IN SATURATED
ZONE (CASING AND WELL SCREEN)
CONFINING LAYER
FIGURE 3-2. COMPOSITE WELL CONSTRUCTION
(INERT CONSTRUCTION MATERIALS IN SATURATED ZONE)
3-10
-------
phase imraiscibles is possible, an eight to ten-inch enclosed extension of
the casing should be used to capture a sample. The top of this sampling
cup should lie at the formation interface, and a dedicated bailer used to
draw samples.
3.2.2 Monitoring Well Filter Pack and Annular Sealant
The materials used to construct the filter pack should be chemically
inert (e.g., clean quartz sand, silica, or glass beads), well rounded,
and dlmensionally stable (see Section 3.3 for more detail on well intake
design). Fabric filters should not be used as filter pack materials.
Natural gravel packs are acceptable provided that the owner/operator
conducts a sieve analysis so that the filter pack is appropriate given
well screen slot size.
The materials used to seal the annular space must prevent the
migration of contaminants to the sampling zone from the surface or
intermediate zones and prevent cross contamination between strata. The
materials should be chemically resistant to ensure seal integrity during
the life of the monitoring well and chemically inert so they do not
affect the quality of the ground-water samples. Figure 3-1 illustrates
an appropriate distribution of annular sealants. A minimum of two feet
of certified coarse grit sodium bentonite should immediately overlie the
filter pack. Where the saturated zone extends above the well screen,
certified coarse grit sodium bentonite only should be used. A cement and
bentonite mixture, bentonite chips/pellets, or antishrink cement mixtures
should be used as the annular sealant in the unsaturated zone above the
certified coarse grit sodium bentonite seal and below the frost line.
Above the frost line the cap should be composed of concrete blending into
a cement apron extending three feet from the outer edge of the borehole.
The untreated sodium bentonite seal should be placed around the
casing either by dropping it directly down the borehole or, if a
hollow-stem auger is used, putting the bentonite between the casing and
the inside of the auger stem. Both of these methods present a potential
3-11
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for bridging. In shallow monitoring wells, a tamping device should be
used to reduce this potential. In deeper wells, it may be necessary to
pour a small amount of formation water down the casing to wash the
bentonite down the hole.
The cement-bentonite mixture should be prepared using formation
water and placed in the borehole using a tremie pipe. The tremie method
ensures good sealing of the borehole from the bottom.
The remaining annular space should be sealed with expanding cement
to provide for security and an adequate surface seals. Locating the
interface between the cement and bentonite-cement mixture just below the
frost line serves to protect the well from damage due to frost heaving.
The cement should be placed in the borehole using the tremie method.
Figure 3-1 illustrates an appropriate protective steel cap around
the well casing. A one-quarter inch vent hole provides an avenue for the
escape of gas. The protective cap guards the casing from damage and the
locking cap serves as a security device to prevent well tampering.
3.3 Well Intake Design
The owner/operator must design and construct the intake of the
monitoring wells so as to: (1) allow sufficient ground-water flow to the
well for sampling; (2) minimize the passage of formation materials
(turbidity) into the well; and (3) ensure sufficient structural integrity
to prevent the collapse of the intake structure.
For wells completed in unconsolidated materials, the intake of a
monitoring well should consist of a screen or slotted casing with
openings sized to ensure that formational material is prohibited from
passing through the well during development. Extraneous fine-grained
material (clays and silts) that have been dislodged during drilling may
be left on the screen and the water in the well. These fines should be
removed from the screen and surrounding area during development. The
owner/operator should use commercially manufactured screens or slotted
casings. Field slotting of screens should not be allowed.
3-12
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The annular space between the face of the formation and the screen
or slotted casing should be filled to minimize passage of formation
materials into the well. The owner/operator should therefore install a
filter pack in each monitoring well that is constructed on site.
Further, in order to ensure discrete sample horizons, the filter pack
should extent no more than two feet above the well screen as illustrated
in Figure 3-1.
3.4 Well Development
After the owner/operator has completed constructing monitoring
wells, natural hydraulic conductivity of the formation should be restored
and all foreign sediment removed to ensure turbid-free ground-water
samples.
A variety of techniques are available for developing a well. To be
effective, they require reversals or surges in flow to avoid bridging by
particles, which is common when flow is continuous in one direction.
These reversals or surges can be created by using surge blocks, bailers,
or pumps. Formation water should be used for surging the well, in low
yielding water-bearing formations, an outside source of water may
sometimes be introduced into the well to facilitate development. In
these cases, this water should be chemically analyzed to ensure that it
cannot contaminate the aquifer. The owner/operator should not use air in
the development of wells. The owner/operator should steam clean all
equipment used to develop a well prior to its introduction into the well.
The owner/operator must develop wells so that they are clay and
silt-free. If, after development of the well is complete, it continues
to yield turbid ground-water samples, the owner/operator should follow
the procedure described in Figure 3-3. The acceptance/rejection value of
five nephelometric turbidity units (N.T.U.) is based on the need to
minimize biochemical activity and possible interference with ground-water
sample quality.
3-13
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TURBID GROUNDWATER
SAMPLE
ANALYZE THE SAMPLE
WITHATURBIDMETER
NO
REPURGE WELL (4.2.4)
YES
SAMPLE IS ACCEPTABLE
REANALYZE WITH TURBIDMETER
NO
ANALYZE SAMPLE USING
X-RAY DIFFRACTION
YES
YES
SAMPLE IS
ACCEPTABLE
ANALYZE
FOR ORGANICS
YES
SAMPLE IS ACCEPTABLE:
WELL NETWORK IS USEABLE
ARE
ORGANICS
PRESENT?
PRIMARILY
SILT&
CLAY?
NO
PRIMARILY METALLIC COMPOUNDS;
RETAIN WELL NETWORK
WELL HAS BEEN IMPROPERLY
CONSTRUCTED AND/OR DEVELOPED;
DO NOT USE SAMPLES
FIGURE 3-3. DECISION CHART FOR TURBID GROUND-WATER SAMPLES
3-14
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3.5 Documentation o£ Well Design and Construction
In the context of a compliance order, the enforcement official
should require the owner/operator to compile information on the design
and construction of wells. Such information may include:
• date/time of construction;
• drilling method and drilling fluid used;
• well location (± 0.5 ft.);
• bore hole diameter and well casing diameter;
• well depth (± 0.1 ft.)
• drilling and lithologic logs
• casing materials;
• screen materials and design;
• casing and screen joint type;
• screen slot size/length;
• filter pack material/size;
• filter pack volume;
• filter pack placement method;
• sealant materials;
• sealant volume;
• sealant placement method;
• surface seal design/construction;
• well development procedure;
• type of protective well cap;
• ground surface elevation (+ 0.01 ft.);
• well cap elevation (+ 0.01 ft.).
• top of casing elevation (± 0.01 ft.); and
• detailed drawing of well (include dimensions).
3.6 Specialized Well Designs
There are two cases where owner/operators should use special
monitoring well designs:
3-15
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• where the owner/operator has chosen to use dedicated pumps to
draw ground-water samples; and
• where light and/or dense phase immiscibles may be present.
If the owner/operator elects to use a dedicated system, it should
either be a teflon or stainless steel 316 bailer, or a dedicated positive
gas displacement bladder pump composed of the same two materials. The
introduction of this pump, however, necessitates certain changes in the
well cross section depicted in Figure 3-1. Figure 3-4 represents an
appropriate cross section of a well which utilizes a dedicated positive
gas displacement bladder pump as the sampling device/well evacuation
device. The principal change is the addition of a two-inch diameter pump
with a Teflon outlet tubing to the well. A four-inch interior diameter
outer well casing should easily accommodate this additional equipment.
However, should a larger pump (e.g., three inches in diameter) be
required because of greater well depth or yield, a larger outer casing
may prove necessary (six-inch interior diameter). The pump should be
positioned midway along the screened interval, and the top of its sub-
casing should extend into the well cap as depicted in Figure 3-4. The
subcasing may have to be braced within the outer casing to reduce
potential deformation.
If light and dense phase immiscible layers are present, the owner/
operator must obtain discrete samples of them. Figures 3-5 and 3-6
illustrate well cross sections which should be used for the purpose of
sampling the light phase and dense phase immiscible layers, respectively,
where the owner/operator has chosen to use a dedicated positive gas
displacement bladder pump. A subcasing is added to the Figure 3-1 cross
section which is sampled using a bottom filling bailer. To capture a
sample of light phase immiscible layers, both the outer casing and
subcasing should be screened at horizons where floaters are expected.
Further, the subcasing should extend to within a couple of inches of the
bottom of the dense phase sampling cup to permit bailer sampling of the
3-16
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1/4" GAS VENT
STEEL PROTECTOR CAPS WITH LOCKS
WELL CAPS
CONCRETE CAP (EXPANDING CEMENT)
OUTLET PIPE (TEFLON TUBING)
WELL DIAMETER = 4" - 6" (OR AS
REQUIRED BY PUMPING DEVICE)
CEMENT AND SODIUM
BENTONITE MIXTURE
CERTIFIED COARSE GRIT SODIUM
BENTONITE (MINIMUM THICKNESS
2 FEET OR MORE ABOVE FILTER PACK)
FILTER PACK (2 FEET OR LESS
ABOVE SCREEN)
POTENTIOMETRIC SURFACE
SCREENED INTERVAL
POSITIVE GAS DISPLACEMENT
BLADDER PUMP
XX XXXX XX «
XX XXXX XX
XXX XXX XXX
ZONE OF LESSER PERMEABILITY x X
XXX XXXXXXX
X XX XX XXX
8" - 10" DENSE PHASE SAMPLING CUP v v v
A A A
- BOTTOM CAP X X X x x *
XXX XXX XX X
FIGURE 3^». MONITORING WELL CROSS-SECTION -DEDICATED
POSITIVE GAS PLACEMENT BLADDER PUMP
3-17
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dense phase immiscible layer(s). Where well clusters are employed, one
well in the cluster may be screened at horizons where floaters are
expected (e.g., water table, Figure 3-5), another at horizons where dense
phases are expected (e.g., aquifer/aquiclude interface, Figure 3-6), and
others within other portions of the uppermost aquifer. Only those wells
in the cluster intended to sample for the light phase should have a
subcasing and outer casing screened to capture it, and only those wells
intended to produce samples of dense phase immiscible layers should
employ a subcasing extending into a dense phase sampling cup. Wells in
the cluster which are not intended to generate discrete immiscible
samples do not need the subcasing.
3.7 Evaluation of Existing Wells
The enforcement official must decide if wells--as designed and
constructed--allow for the collection of representative ground-water
samples. There are two situations the enforcement official may
encounter: (1) where existing wells produce consistently turbid samples,
i.e., greater than 5 N.T.U.; (2) where the owner/operator can produce
little or no documentation on how the wells were designed and installed.
Turbid wells or lack of information on well design and construction
may prompt the enforcement official to order the owner/operator to replace
monitoring wells. In other, less obvious cases, the enforcement official
must use best judgment in deciding when to order an owner/operator to
replace wells. It is likely that many owner/operators have not designed
or installed wells strictly in accordance with the guidance in this
chapter The enforcement official must decide if the owner/operator's
wells- as built--allow the owner/ operator to collect representative
ground-water samples. This may not be an easy judgment to make. In
cases where it is not clear if the owner/ operator's wells can produce
representative ground-water samples, the enforcement official may con-
sider requiring the owner/operator to conduct a field demonstration.
3-18
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1 /4" GAS VENT
STEEL PROTECTOR CAP WITH LOCKS
WELL CAPS
WELL DIAMETER - 4" - 6" (OR AS
REQUIRED BY PUMPING DEVICE]
BOREHOLE DIAMETER = 12'
SUBCASING = 2" (OR AS REQUIRED
BY SAMPLING DEVICE)
CONCRETE CAP (EXPANDING CEMENT)
OUTLET PIPE (TEFLON TUBING)
CEMENT AND SODIUM
BENTONITE MIXTURE
CERTIFIED COARSE GRIT SODIUM
BENTONITE (MINIMUM THICKNESS
2 FEET OR MORE ABOVE FILTER PACKI
FILTER PACK 2 FEET OR LESS
ABOVE SCREEN!
POTENTIOMETRIC SURFACE
DEDICATED POSITIVE GAS
DISPLACEMENT BLADDER PUMP
SCREENED INTERVAL
XXXXXXX XX
XXXXXX XXX
XX XXXXX XX
x ZONE OF LESSER PERMEABILITY x x
x xxxxxx xxx
X XXXXX x
8" - 10" DENSE PHASE SAMPLING CUP X X
xlx x x xx x x
- BOTTOM CAP XXXXX
XXX XXXXXX
FIGURE 3-5, MONITORING WELL CROSS-SECTION-DEDICATED POSITIVE
GAS DISPLACEMENT BLADDER PUMP AND SUBCASING FOR
DISCRETE SAMPLING OF LIGHT PHASE IMMISCIBLE LAYERS
3-19
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STEEL PROTECTOR CAP WITH LOCKS
WELL CAPS
WELL DIAMETER = 4" - 6" (OR AS
REQUIRED BY PUMPING DEVICE)
BOREHOLE DIAMETER = 12"
SUBCASING = 2" (OR AS REQUIRED
BY SAMPLING DEVICE)
CONCRETE CAP (EXPANDING CEMENT)
OUTLET PIPE (TEFLON TUBING)
CEMENT AND SODIUM
SENTONITE MIXTURE
POTENTIOMETRIC SURFACE
CERTIFIED COARSE GRIT SODIUM
BENTONITE (SHOULD EXTEND TO
UPPER LIMIT OF SATURATED ZONE)
FILTER PACK (2 FEET OR LESS
ABOVE SCREEN)
KSCREENED INTERVAL
I
DEDICATED POSITIVE GAS
DISPLACEMENT BLADDER PUMP
XXXXX XX X
XXX XXXXX X
XXX XXXXX
X ZONE OF LESSER PERMEABILITY XXX
XXXX XXXX
XXXXX
8" - 10" DENSE SAMPLING CUP
x x i
X X
X XXXX X XX
BOTTOM CAP XXXXX
X XXXX XXX
FIGURE 3-6. MONITORING WELL CROSS-SECTION - DEDICATED POSITIVE GAS
DISPLACEMENT BLADDER PUMP AND SUBCASING FOR DISCRETE
SAMPLING OF DENSE PHASE IMMISCIBLE LAYERS
3-20
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This demonstration would involve the installation of new well(s) near
existing wells. The owner/operator would sample for and analyze the same
set of parameters in both wells. If parameter values are equivalent, the
enforcement official should assume the owner/operator's existing wells
are producing representative samples.
3-21
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CHAPTER FOUR
SAMPLING AND ANALYSIS
Section 265.92 requires the owner/operator to prepare and implement
a written ground-water sampling and analysis (S&A) plan. This plan must
include procedures and techniques for sample collection, sample
preservation and shipment, analytical procedures and chain of custody
control. The owner/operator's S&A plan is an important document. It
allows the enforcement official to thoroughly review how the
owner/operator has structured the S&A program. Also, comparison of the
written plan to field activities will allow the enforcement official to
ensure the owner/operator is, in fact, properly collecting and analyzing
ground-water samples. The purpose of this chapter is to describe
important elements of written S&A plans and to discuss the level of
detail that owner/operators should include in their plans.
EPA has observed a number of problems in the way in which owner/
operators prepare their S&A plans or implement their S&A programs. Some
of the more common problems are listed below.
• Owner/operators have not prepared S&A plans or do not keep plans
on site.
• Plans contain very little information or do not adequately
describe the S&A program the owner/operator is employing at his
facility.
• Field sampling personnel are not following the written plan or
are not even aware that it exists.
• Improper evacuation techniques are used particularly in regards
to the identification and collection of immiscible contaminants.
• Sampling equipment is used that may alter chemical constituents
in ground water.
• Sampling techniques are used that may alter chemical composition
of samples particularly in regard to stripping of volatile
organic compounds in samples.
4-1
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• Facility personnel are not using blanks, standards, and spiked
samples to correct analytical results for changes in sample
quality after collection.
• Field personnel do not properly clean nondedicated sampling
equipment after use.
• Field personnel are placing sampling equipment (rope, bailer,
tubing) on the ground where it can become contaminated prior to
use.
• Field personnel do not document their field activities adequately
(e.g., keep sampling logs).
• Field personnel are not following proper chain-of-custody
procedures.
• Little attention is paid to data reporting errors or anamolies.
• Facility personnel have not reviewed the QA/QC procedures being
used by the laboratory that is analyzing their ground-water
samples.
This chapter describes important elements in S&A plans (Section 4.1),
and then discusses the level of detail the owner/operator should include
in his plan in regard to each S&A element (Sections 4.2 through 4.6).
Furthermore, this chapter describes important aspects of evaluating the
field implementation of S&A plans (Sections 4.2 through 4.6). Section 4.7
describes how enforcement officials may examine ground-water data to
identify evidence of problems in the way owner/operators acquire,
process, and evaluate data.
4.1 Elements of Sampling and Analysis Plans
The owner/operator's S&A plan should, at minimum, address a number
of elements. Specifically, the S&A plan should include information on:
• Sample collection (Section 4.2);
• Sample preservation and handling (Section 4.3);
• Chain of custody control (Section 4.4);
• Analytical procedures (Section 4.5); and
• Field and laboratory quality assurance/quality control
(Section 4.6).
4-2
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4.2 Sample Collection
4.2.1 Measurement of Static Water Level Elevation
The owner/operator's sampling and analysis plan should include
provisions for measurement of static water level elevations in each
well. Collection of water level elevation on a continuing basis is
important to determine if horizontal and vertical flow gradients have
changed since initial site characterization. A change in hydrologic
conditions may necessitate modification to the design of the owner/
operator's ground-water monitoring system. The S&A plan should specify
the device to be used for water level measurements as well as the
procedure for measuring water levels.
The owner/operator's field measurements should include depth to
standing water and total depth of the well to the bottom of the intake
screen structure. The measurements should be taken to 0.1 foot. Each
well should have a reference point from which its water level measurement
is taken. The reference point should be established by a licensed
surveyor and is typically located at the top of the well casing with
locking cap off. The reference point should be established in relation
to mean sea level and the survey should also note the well location
coordinates. The device which is used to detect the water level surface
must be sufficiently sensitive so that a measurement to +0.1 foot can be
obtained reliably. A steel tape will usually suffice, however, it is
recommended that an electronic device (e.g., M-Scope or sounder) be used
to measure depth to the surface of the ground water or light phase
immiscibles.
4.2.2 Detection of Immiscible Layers
The owner/operator's S&A plan should include provisions for
detecting immiscible contaminants, i.e., "floaters" and "sinkers" if the
owner/operator manages wastes of this type at his facility. "Floaters"
are those relatively insoluble organic liquids which are less dense than
4-3
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water that spread across the water table surface, "sinkers" are those
relatively insoluble organic liquids which are more dense than water and
tend to migrate vertically through the sand and gravel aquifers to the
underlying aquitard. The detection of these immiscible layers requires
specialized equipment which must be used before the well is evacuated for
conventional sampling. The S&A plan should specify the device to be used
to detect "floaters" and "sinkers" as well as the procedures to be used
for detecting and sampling these contaminants.
Owner/operators should follow the procedures below for detecting the
presence of light and/or dense phase immiscible organic layers should be
undertaken before the well is evacuated for conventional sampling:
1. Remove the locking and protective caps.
2. Sample the air in the well head for organic vapors using either
an HMD or OVA, and record measurements.
3. Determine the static liquid level using a manometer or
acoustical sounder, and record the depth.
4. Lower an interface probe into the well to determine the exitence
of any immiscible layer(s), light and/or dense.
The air above the well head should be sampled in order to determine
the potential for fire, explosion, and/or toxic effects on workers. This
test also serves as a first indication of the presence of immiscible
organics. A manometer or acoustical sounder may provide an accurate
reading of the depth to the surface of the liquid in the well, but
neither are capable of differentiating between the water table and the
surface of a floater. Nonetheless, it is very useful to determine that
depth first to guide the lowering of the interface probe. The interface
probe serves two related purposes. First, as it is lowered into the
well, the probe registers when it is exposed to an organic liquid and
thus identifies the presence of immiscible layers. Careful recording of
the depths of the air/floater and floater/water interfaces establishes a
measurement of the thickness of the light phase immiscible layer.
4-4
-------
Secondly, as the probe is lowered through the light phase immiscible
layer, it indicates the depth to the static water level. The presence of
floaters precludes the exclusive use of sounders to make a determination
of static water level. Dense phase immiscibles layers are detected by
lowering the device to the bottom of the well where again the interface
probe registers the presence of organic liquids.
Sampling of immiscible fractions should precede well evacuation
procedures. A bottom filling bailer should be lowered to the levels at
which the light and dense phase immiscibles are found and a sample
taken. Care should be taken to gently lower the bailer to avoid, as much
as possible, disturbing the interface between the organic liquid and
water.
4.2.3 Well Evacuation
The water standing in a well prior to sampling may not be
representative of in-situ ground-water quality. Therefore, the
owner/operator should remove the standing water in the well so that water
which is representative of the formation can replace the standing water.
The owner/operator's S&A plan should include detailed, step-by-step
procedures for evacuating wells. The equipment the owner/operator plans
to use to evacuate wells should also be described.
The owner/operator's evacuation procedure should ensure that all
stagnant water is replaced by fresh formation water upon completion of
the process. The owner/operator should draw the water down from above
the screen in the uppermost part of the water column to ensure fresh
water from the screen will move upward.
The procedure the owner/operator should use for well evacuation
depends on the yield of the well. When evacuating low yield wells, the
owner/operator should evacuate wells to dryness once. As soon as the
well recovers, the first samples the owner/operator should remove are the
ones to be tested for volatilization sensitive parameters (e.g., total
4-5
-------
organic halogens) and/or pH, oxidation reduction. Whenever full recovery
exceeds three hours, the owner/operator should extract the remaining
samples in order of their volatility as soon as sufficient volume is
available for a sample for each parameter. Parameters that are not pH
sensitive or subject to loss through volatilization, (such as nonvolatile
or nonreactive organics) should be drawn last. At no time should an
owner/operator pump a well to dryness if the recharge rate causes the
formation water to vigorously cascade down the intake screen and
accelerate the loss of volatiles. If this is anticipated to be a
problem, the owner/operator should purge three casing volumes from the
well at a rate which does not cause to recharge water to be excessively
agitated. For higher yielding wells, the owner/operator should evacuate
three casing volumes prior to sampling.
In order to minimize the introduction of contamination into the well
positive gas displacement teflon bladder pumps are recommended for
purging wells. Teflon or stainless steel bailers are also recommended
purging equipment. Where these devices cannot be used, peristalitic
pumps, gas-lift pumps, centrifugal pumps, and venturi pumps may be used.
Some of these pumps produce volatilization and high pressure
differentials, causing variability in the analysis of pH, specific
conductance, metals, and volatile organic samples. They are, however,
acceptable for purging the wells if sufficient time is allowed to let the
water stabilize prior to sampling.
When purging equipment must be reused, it should be decontaminated
with a water wash and a deionized distilled water rinse. Purging
equipment which becomes heavily contaminated should be cleaned with a
nonphosphate detergent wash followed by rinsing with hexane and deionized
distilled water. Clean gloves should be worn by the sampling personnel.
A clean plastic sheet should be placed adjacent to or around the well in
order to prevent surface soils from coming in contact with the purging
equipment and lines, which in turn could introduce contaminants to the
well.
4-6
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4.2.4 Sample Withdrawal
The technique used to withdraw a ground-water sample from a well
should be selected based on a consideration of the parameters which will
be analyzed in the sample. To ensure the ground-water sample is
representative of the formation, it is important to avoid physically
altering or chemically contaminating the sample during the withdrawal
process. In order to minimize the possibility of sample contamination,
the owner/operator should:
1. Use only Teflon* or stainless steel (316) sampling devices,
and
2. Use dedicated samplers for each well. (If a dedicated sampler
is not available for each well, the owner/operator should
thoroughly clean the sampler between sampling events and the
owner/operator should take blanks and analyze them to ensure
cross-contamination has not occurred.)
The owner/operator's S&A plan should specify in detail the devices
the owner/operator will use for sample withdrawal. The plan should state
that devices are either dedicated to a specific well or are capable of
being fully disassembled and cleaned between sampling events. Procedures
for cleaning the sampling equipment should be included in the plan. Any
special sampling procedures that the owner/operator must use to obtain
samples for a particular constituent (e.g., TOX or TOC) should also be
described in the plan.
When used properly, the following are acceptable sampling devices
for all parameters:
• Bottom valve bailers (Teflon or stainless steel 316); and
• Positive gas displacement bladder pump
Sampling equipment should be constructed of inert material. Equipment
with neoprene fittings, PVC bailers, tygon tubing, silicon rubber
bladders, neoprene impellers, polyethylene, and vitron are not acceptable.
*Tradename for polyperfluoroethylene
4-7
-------
If the owner/operator is using bailers, "Teflon"-coated wire, single
strand stainless steel wire, or monofilament should be used to raise and
lower the bailer. Braided cables, polyethylene or nylon cords should not
be used because it may not be possible to thoroughly decontaminate these
materials prior to sampling.
The owner/operator may use Teflon or stainless steel 316 bailers for
any depth well. A single positive gas displacement bladder pump or
several pumps connected in series may be used for wells 150 to 400 feet
deep. For wells greater than 400 feet deep, the owner/operator should
use bailers with a manual or powered winch to raise and lower the device
in the well.
While in the field, the enforcement official should observe the
owner/operator's sampling technique to ensure that the owner/operator
satisfies the following:
• Positive gas displacement bladder pumps should be operated in a
continuous manner so that they do not produce pulsating samples
that are aerated in the return tube or upon discharge;
• Check valves should be designed and inspected to assure that
fouling problems do not reduce delivery capabilities or result in
aeration of the sample;
• Sampling equipment (e.g., especially bailers) should never be
dropped into the well because this will cause degassing of the
water upon impact;
• The bailer's contents should be transferred to a sample container
in a way that will minimize agitation and aeration; and
• Clean sampling equipment should not be placed directly on the
ground or other contaminated surfaces prior to insertion into the
well.
When dedicated equipment is not used for sampling (or well
evacuation), the owner/operator's sampling plan should include procedures
for disassembly and cleaning of equipment before each use. If the
constituents of interest are inorganic, the first rinse should be a
4-8
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dilute (0.1 N) hydrochloric acid or nitric acid and the second rinse
should be distilled water or deionized water. Dilute hydrochloric acid
is generally preferred to nitric acid when cleaning stainless steel
| because nitric acid may oxidize stainless steel. When organics are the
1 constituents of concern, the owner/operator should wash equipment with a
i
, nonphosphate detergent and rinse with tap water, distilled water,
1 acetone, and finally pesticide-quality hexane, in that order. The
sampling equipment should be thoroughly dried before use to ensure that
the residual cleaning agents (e.g., acetone, HC1) are not carried over to
i the sample.
When collecting samples using a positive gas displacement bladder
pump for volatile analysis, pumping rates should not exceed
100 milliliters/minute. Higher rates can increase the loss of volatile
constituents and can cause fluctuation in pH and pH sensitive analytes.
Once the portions of the sample reserved for the analysis of volatile
components has been collected, the owner/operator may use higher pumping
rates particularly if a large sample volume must be collected.
4.2.5 In-Situ or Field Analyses
Several parameters are physically or chemically unstable and must be
tested either in the borehole using a probe (in-situ) or immediately
after collection using a field test kit. Examples of several unstable
parameters include pH, redox potential, chlorine, dissolved oxygen, and
temperature. Although specific conductivity (analogous to electrical
resistance) is relatively stable, it is recommended that this
characteristic be determined in the field. Most conductivity instruments
require temperature compensation, therefore temperatures of the sample
should be measured at the time conductivity is determined. If the
owner/operator uses probes (pH electrode, specific ion electrode,
thermistor) to measure any of the above parameters, it is important that
this is done after well evacuation and after any samples for chemical
4-9
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analysis have been collected so that the probe(s) do not contaminate the
sample designated for laboratory analysis. Similarly, if the unstable
parameters are to be determined in a sample withdrawn from a well, the
owner/operator should split the sample into at least two separate
portions, one for field testing and the other for laboratory analysis.
Monitoring probes should not be placed in containers containing
ground-water for laboratory analysis.
The owner/operator should complete the calibration of any in-situ
monitoring equipment or field test probes and kits before each use
according to the manufacturers specifications and consistent with sw-846.
4.3 Sample Preservation and Handling
Many of the constituents and parameters that are included in
ground-water monitoring programs are not stable, and therefore, sample
preservation is required. Test Methods for Evaluating Solid Waste -
Physical Chemical Methods (sw-846, Section 1.4.6.2.3) has a discussion
for each analytical technique on the choice sample preservation
procedures. In addition, SW-846 (Section 1.2.2) specifies the sample
containers that the owner/operator should use for each constituent or
common set of parameters. The owner/operator should identify in the S&A
plan which preservation methods and sample containers will be employed.
Each sampling and analysis plan should also detail all procedures and
techniques for transferring the samples to either a field or off-site
laboratory.
Improper sample handling may lead to loss of contaminant
constituents in the sample. Samples should be transferred in the field
from the sampling equipment directly into to the container that has been
specifically prepared for that given parameter or set of compatible
parameters. It is not an acceptable practice for samples to be
composited in a common container in the field and then split in the
laboratory, nor poured first into a wide mouth container then transferred
4-10
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into smaller jars. In regard to volatile organics, the S&A plan should
specify how the samples will be transferred from the sample collection
device to the sample container to reduce loss through volatilization.
When using a bailer to collect samples for the analysis of volatiles, the
sample may be transferred to a beaker which will facilitate the filling
of a volatile organics analysis (VGA) vial. The water should be poured
from the beaker to the VOA vial so that the vial overflows and no bubbles
or headspace is left in the vial.
4.3.1 Sample Containers
The owner/operator's S&A plan should identify the type of sample
containers to be used to collect samples as well as procedures the
owner/operator will use to ensure that sample containers are free of
contaminants prior to use.
When metals are the analytes of interest, polyethylene containers
with polypropylene caps should be used. When organics are the analytes
of interest, glass bottles with Teflon-lined caps should be used. Glass
bottles may be used to store samples for metals analysis providing the
caps are Teflon-lined and the appropriate preservative has been used.
The plan should refer to the specific analytical method (in SW-846,
Section 1.2.2) which designates an acceptable container.
Containers should be cleaned to suit the type of analysis the sample
will be subjected to. When samples are to be analyzed for metals
(SW-846, Method 6010), the sample containers as well as the laboratory
glassware should be thoroughly washed with nonphosphate detergent and tap
water, and rinsed with (1:1) nitric acid, tap water, (1:1) hydrochloric
acid, tap water, and finally Type II water, in that order. Chromic acid
may be useful to remove organic deposits from glassware; however, the
analyst should be cautioned that the glassware must be thoroughly rinsed
with water to remove the last traces of chromium. The use of chromic
acid can cause a contamination problem for the determination of chromium
4-11
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if the glassware is not rinsed properly. If it can be documented through
an active analytical quality control program using spiked samples and
reagent blanks that certain steps in the cleaning procedure are not
required for routine samples, those steps may be eliminated from the
procedure.
Similarly, an EPA-approved procedure (SW-846, Method 8080) is
available for cleaning containers used to store samples for organics
analysis. The sampling container should be emptied of any residual
materials followed by washing with a nonphosphate detergent in hot
water. Rinse with tap water, distilled water, acetone, and finally
pesticide-quality hexane. Heavily contaminated glassware may require
treatment in a muffle furnace at 400°C for 15 to 30 minutes. Glassware
should be sealed/stored in a clean environment immediately after drying
or cooling to prevent any accumulation of dust or other contaminants.
Store inverted or capped with aluminum foil.
The cleanliness of a batch of precleaned bottles should be verified
by the use of a trip blank. Each time a group of bottles is prepared for
use in the field, one bottle of each type (e.g., glass, Teflon,
polyethylene) should be selected from the batch and filled with deionized
water. The bottles filled with the blank should be transported to the
sampling location and returned to the laboratory in a manner identical to
the handling procedure used for the samples. Trip blanks should be
subjected to the same analysis as the ground water. Any contaminants
found in the trip blanks could be attributed to (1) interaction between
the sample and the container, (2) contaminated deionized water, or (3) a
handling procedure which alters the sample. The concentration levels of
any contaminants found in the trip blank should not be used to correct
the ground-water data. The contaminant levels should be noted and if the
levels are significant compared to the field sample results, the owner/
operator should resample the ground water.
4-12
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4.3.2 Sample Preservation
The owner/operator's S&A plan should identify sample preservation
methods that the owner/operator plans to use. Methods of sample
preservation are relatively limited and are generally intended to
(1) retard biological action, (2) retard hydrolysis, and (3) reduce
absorption effects. Preservation methods are generally limited to pH,
control, chemical addition, refrigeration, and freezing. The
owner/operator should refer to the specific preservation method in
SW-846, Section 1.4.6.2.3 that will be used for the constituent in the
sample. A summary of adequate sample containers and sample preservation
measures is presented in Table 4-1.
4.3.3 Special Handling Considerations
Organics
Samples requiring analysis for organics should not be filtered.
Samples should not be transferred from one container to another because
losses of organic material onto the walls of the container may occur.
Total organic halogens (TOX) and total organic carbon (TOC) samples
should be handled and analyzed as materials containing volatile
organics. No headspace should exist in the sample containers to minimize
the possibility of volatilization of organics. Field logs and laboratory
analysis reports should note the headspace in the sample container(s) at
the time of receipt by the laboratory as well as at the time the sample
was first transferred to the sample container at the wellhead.
Metals
Metals which migrate through the unsaturated (vadose) and saturated
zones and arrive at a ground-water monitoring well are typically in a
dissolved state. Particles (e.g., silt, clay) which may be present in
the well even after well evacuation procedures may absorb or adsorb
various metals species to effectively lower the dissolved metal content
4-13
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TABLE 4-1
SAMPLING AND PRESERVATION PROCEDURES FOR DETECTION MONITORING3
Parameter
PH
Specific conductance
TOC
TOX
Chloride
Iron
Manganese
Sodium
Phenols
Sulfate
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Minimum Volume
Recommended Maximum Required for
Container^ Preservative Holding Time Analysis
Indicators of Ground-Water Contamination0
T, P, G Field determined 2 hours
T, P, G f eld determined None
G, Teflon-lined Cool 4°C, HC1 to 28 days
cap pH <2
G, amber, Teflon- Cool 4°C, add 1 ml of 7 days
lined cap 1. 1M sodium sulfite
Ground-Water Quality Characteristics
T, P, G 4°C 28 days
T, P Field Acidified*1 6 months
to pH <2 with HNC^
G 4°C/H0SO, to pH <2 28 days
i 4
T, P, G Cool, 4°C 28 days
EPA Interim Drinking Water Characteristics
T, P Total Metals 6 months
Field acidified to
pH <2 with HN03
6 months
Dissolved Metals
1. Field filtration
(0.45 micron)
2. Acidify to pH <2
25 ml
100 ml
4 x 15 ml
4 x 15 ml
50ml
200 ml
500ml
50 ml
1,000 ml
1,000 ml
Fluoride
Nitrate
T, P
T, P, G
with HN03
Field acidified to
pH <2 with HN03
(Continued)
28 days
48 hours
300 ml
1 ,000 ml
4-14
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TABLE 4-1 (Continued)
SAMPLING AND PRESERVATION PROCEDURES FOR DETECTION MONITORING
Parameter
Endrin
Lindane
Hethoxychlor
Toxaphene
2,4 0
2,4,5 TP Silvex
Radium
Gross Alpha
Gross Beta
Col i form bacteria
Recommended
Container1* Preservative
T, G Field acidified to
pH <2 with HN03
P, G Field acidified to
pH <2 with HN03
PP, G (sterilized) Cool, 4°C
Maxinun
Holding Time
24 hours
6 months
6 hours
Minimum Volume
Required for
Analysis
1,000 ml
1 gallon
200 ml
Cyanide
Oil and Grease
Other Ground-Water Characteristics of Interest
P, G Cool, 4°C, NaOH to 14 days
G only
Hazardous constituents G only
(§261, Appendix VIII)
Cool, 4°C, NaOH to 14 days 500 ml
pH >12
Cool, 4°C H2S04 to 28 days 100 ml
pH <2
Cool, °4C 7 days 1 gallonf
References: Test Methods for Evaluating Solid Waste - Physical/Chemical Methods. SW-846
(2nd edition, 1982).
Methods for Chemical Analysis of Hater and Wastes. EPA-600/4-79-020.
Standard Methods for the Examination of Hater and Wastewater. 16th edition (1985).
''Container Types:
P = Plastic (polyethylene)
G = Glass
T = Teflon
PP = Polypropylene
cBased on the requirements for detection monitoring (§265.93), the owner/operator must collect
a sufficient volume of ground water to allow for the analysis of four separate replicates.
(Continued)
4-15
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TABLE 4-1 (Continued)
SAMPLING AND PRESERVATION PROCEDURES FOR DETECTION MONITORING
dln the event that HN03 cannot be used because of shipping restrictions, the sample should be
refrigerated to 4°C, shipped immediately, and acidified on receipt at the laboratory.
samples from nonchlorinated drinking water supplies concentrated ^$04 should be added
to lower sample pH to less than 2. The sample should be analyzed before 14 days.
fy)r as required by the procedures (SW-846) for the specific hazardous constituents being
assessed.
4-16
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in the well water. Ground-water samples on which metals analysis will be
conducted should be split into two portions. One portion should be
filtered through a 0.45 micron filter (glass fiber or membrane),
transferred to a bottle, preserved with nitric acid to a pH less than 2
(Table 4-1) and analyzed for dissolved metals. The remaining portion
should be transferred to a bottle, preserved with nitric acid and
analyzed for total metals. Any difference in concentration between the
total and dissolved fractions may be attributed to the original metal
content of the particles and any migration of dissolved metals to the
particles.
Blanks
Various types of blanks should be used to verify that the sample
collection and handling process has not affected the quality of the field
samples (see Section 4.6 for more information on field and laboratory
QA/QC programs). The owner/operator should prepare each of the following
field blanks and analyze them for all of the required monitoring
parameters:
Trip Blank - Fill one of each type of sample bottles with deionized
water, transport to the site, handle like a sample, and return to
the laboratory for analysis. One trip blank per sampling event is
recommended.
Equipment Blank - To ensure the sampling device has been effectively
cleaned (in the laboratory or field), fill the device with deionized
water or pump deionized water through the device, transfer to sample
bottle(s) and return to the laboratory for analysis. One equipment
blank each day ground-water monitoring wells are sampled is
recommended.
The results of the analysis of the blanks should not be used to
correct the ground-water data. If contaminants are found in the blanks,
the source of the contamination should be identified and corrective
action, including resampling, should be initiated. Other quality control
samples (e.g., standards, spikes, performance evaluation samples) should
be prepared and analyzed as part of the laboratory operation (see
4-17
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Section 4.6.1). The owner/operator's S&A plan should include provisions
for the use of trip blanks and equipment blanks as well as other QA/QC
activities.
4.4 Chain of Custody
The owner/operator must describe a chain-of-custody program in the
S&A plan. An adequate chain-of-custody program will allow for the
tracing of possession and handling of individual samples from the time of
field collection through laboratory analysis. An owner/operator's chain-
of-custody program should include:
• Sample labels which prevent misidentification of samples;
• Sample seals to preserve the integrity of the sample from the
time it is collected until it is opened in the laboratory;
* Field logbook to record information about each sample collection
during the ground-water monitoring program;
• Chain-of-custody record to establish the documentation necessary
to trace sample possession from the time of collection to
analysis;
• Sample analysis request sheets which serve as official
communication to the laboratory of the particular analysis(es)
required for each sample and provide further evidence that the
chain of custody is complete; and
• Laboratory logbook which is maintained at the laboratory and
records all pertinent information about the sample.
4.4.1 Sample Labels
To prevent misidentification of samples, the owner/operator should
affix legible labels to each sample container. The labels should be
sufficiently durable to remain legible even when wet and should contain
the following type of information:
Sample identification number
Name of collector
Date and time of collection
Place of collection
Parameter(s) requested (if space permits)
4-18
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4.4.2 Sample Seal
In cases where samples may leave the owner/operator's immediate
control, such as shipment to a laboratory by a common carrier (e.g., air
freight), a seal should be provided on the shipping container or
individual sample bottles to ensure the samples have not been disturbed
during transportation.
4.4.3 Field Logbook
An owner/operator or the individual designated to perform
ground-water monitoring operation should keep an up-to-date field logbook
which documents the following:
Identification of well
Well depth
Static water level depth and measurement technique
Presence of immiscible layers and detection method
Well yield - high or low
Collection method for immiscible layers and sample identification
numbers
Well evacuation procedure/equipment
Sample withdrawal procedure/equipment
Date and time of collection
Well sampling sequence
Types of sample containers used and sample identification numbers
Preservative(s) used
Parameters requested for analysis
Field analysis data and method(s)
Sample distribution and transporter
Field observations on sampling event
Name of collector
4.4.4 Chain-of-Custody Record
To establish the documentation necessary to trace sample possession
from time of collection, a chain-of-custody record should be filled out
and accompany every sample. The record should contain the following type
of information:
• Sample number
• Signature of collector
• Date and time of collection
• Sample type (e.g., ground water, immiscible layer)
4-19
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Identification of well
Number of containers
Parameters requested for analysis
Signature of person(s) involved in the chain of possession
Inclusive dates of possession
4.4.5 Sample Analysis Request Sheet
This document should accompany the sample(s) on delivery to the
laboratory and clearly identify which sample containers have been
designated (e.g., use of preservatives) for each requested parameter.
The record should include the following type of information:
• Name of person receiving the sample
• Laboratory sample number (if different than field number)
• Date of sample receipt
• Analyses to be performed
4.4.6 Laboratory Logbook
Once the sample has been received in the laboratory, the sample
custodian and/or laboratory personnel should clearly document the
processing steps which are applied to the sample. All sample preparation
techniques (e.g., extraction) and instrumental methods must be identified
in the logbook. Experimental conditions such as the use of specific
reagents (e.g., solvents, acids), temperatures, reaction times and
instrument settings should be noted. The results of the analysis of all
quality control samples should be identified specific to each batch of
ground-water samples analyzed. The laboratory logbook should include the
time, date, and name of the person who performed each processing step.
4.5 Analytical Procedures
The owner/operator's S&A plan should describe in detail the
analytical procedures that will be used to determine the concentrations
of constituents or parameters of interest. These procedures should
include suitable analytical methods as well as proper quality assurance
and quality control protocols. The required precision, accuracy,
4-20
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detection limits and percent recovery (if applicable) specifications
should be clearly identified in the plan.
The S&A plan should identify one method that will be used for each
specific parameter or constituent. Generally, the plan should specify a
method in SW-846 or an EPA-approved method and clearly indicate if there
are going to be any deviations from the stated method.
Records of ground-water analyses should include the methods used,
extraction date and date of actual analysis. Data from samples which are
not analyzed within recommended holding times should be considered
invalid. Any deviation from an EPA-approved method (SW-846) should be
adequately tested to ensure that the quality of the results meets the
performance specifications (e.g., detection limit, sensitivity,
precision, accuracy) of the reference method.
4.6 Field and Laboratory Quality Assurance/Quality Control
One of the fundamental responsibilities of the owner/operator is the
establishment of continuing programs to ensure the reliability and
validity of field and analytical laboratory data gathered as part of the
overall ground-water monitoring program.
The owner/operator's S&A plan must explicitly describe the QA/QC
program that will be used in the field and laboratory. Many
owner/operators use commercial laboratories to conduct analyses of
ground-water samples. In these cases, it is the owner/operator's
responsibility to ensure that his laboratory of choice is exercising a
proper QA/QC program. The QA/QC program described in the
owner/operator's S&A plan must be used by the laboratory analyzing
samples for the owner/operator.
4.6.1 Field QA/QC Program
The owner/operator's S&A plan should provide for the routine
collection and analysis of two types of QC blanks: trip blanks and
4-21
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equipment blanks. Trip blanks are used to determine if contamination is
introduced from the sample containers (see Section 4.3.3). Equipment
blanks are used to determine if contamination is introduced by the sample
collection equipment (see Section 4.3.3).
All field equipment the owner/operator will use should be calibrated
prior to field use and recalibrated periodically. The owner/operator's
S&A plan should describe a program for ensuring proper calibration of
field equipment. Other QA/QC practices such as sampling equipment
decontamination procedures and chain of custody procedures should also be
described in the owner/operator's S&A plan.
4.6.2 Laboratory QA/QC Program
The owner/operator's S&A plan should provide for the use of
standards, laboratory blanks, duplicates, and spiked samples for
calibration and identification of potential matrix interferences. The
owner/operator should use adequate statistical procedures (e.g., QC
charts) to mon1 or and document performance and implement an effective
program to resolve testing problems (e.g., instrument maintenance,
operator training). Data from QC samples (e.g., blanks, spiked samples)
should be used as a measure of performance or as an indicator of
potential sources of cross-contamination but should not be used to alter
or correct analytical data. These data should be submitted to the Agency
with the ground-water monitoring sample results.
4.7 Evaluation of the Quality of Ground-Water Data
A ground-water sampling and analysis program produces a variety of
geohydrological, geophysical, and ground-water chemical constituent
(GWCC) data. This section pertains primarily to the evaluation of GWCC
data because these data are specifically required by the regulations, are
evaluated in the statistical tests, provide the fundamental evidence used
to determine whether the facility is contaminating the ground water, and
4-22
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are used to determine the extent of plume migration during assessment
monitoring. Also, details regarding how to obtain and identify quality
geohydrological and geophysical data have been discussed in Chapters One
through Three. The GWCC data may be initially presented by the
laboratory on reporting sheets; these data then must be compiled and then
analyzed by the owner/operator prior to submission to the state or EPA in
order to evaluate the degree of ground-water contamination.
It is essential for owner/operator to make sure that during chemical
analysis, compilation, laboratory reporting, computer automation, and
report preparation that data are generated and processed to avoid
mistakes and that data are complete and fully documented. Data must be
accurately reported to have accurate analyses and valid results. If data
errors do occur, statistical analyses cannot discover, correct, or
ameliorate the errors.
The following discussion considers aspects of data quality that may
indicate to the enforcement officer that the data acquisition,
processing, and evaluation were executed poorly or incorrectly.
The specific areas that are addressed include:
• Reporting of low and zero concentration values;
• Number of significant digits;
• Missing data values;
• Outliers; and
• Units of measure.
4.7.1 Reporting of Low and Zero Concentration Values
A critical concern is the interpretation, reporting, and analysis of
GWCCs that are measured at less than (LT) a detection limit of an
analytical procedure. These values, which are referred to as LT
detection limit values, result for a variety of reasons, and enforcement
officers, during the review of data submissions, may confront a variety
of codes which indicate that GWCC concentrations are below a value which
can be measured with certainty.
4-23
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Values that are LT a limit of detection can result when:
• GWCCs are present at extremely low concentrations;
• An insensitive analytical technique has been used; and
• The chemical matrix of the ground water interferes with the
analytical technique.
Low GWCC concentrations may be reported using various conventions
depending on the chemical constituent that was measured, the machine and
method used, the chemical analyst, or the data base/computer manager that
was responsible for automating the data in preparation for analysis and
reporting. Enforcement officers may confront owner/operator data
submissions where the convention was to report a code for LT a limit of
detection with no accompanying number. Alternately, the owner/operator
may submit data where the LT designation accompanies a number that is
consistent throughout the data for that analyte. In otrier instances,
data submissions include LT designations which accompany numbers that
vary among samples. Furthermore, some analytical results may
differentiate between GWCCs present but at concentrations that are LT a
limit of detection and GWCCs that are not present in the sample at all.
It is also possible that the enforcement officer will review data
submissions where the values that accompany a LT designation are
quantification limits rather than LT detection limit values.
Quantification limits are generally some multiple larger (5 or 10 times)
than the smallest concentration that can be measured. It is clear that
the codes used to designate low GWCC concentrations may assume many forms
and may indicate different results; Table 4-2 provides a listing of some
low concentration codes that the enforcement officer is likely to
encounter in data submissions. The purpose of Table 4-2 is not to
endorse particular reporting formats, but to prepare enforcement officers
for a variety of data submissions where low concentrations of GWCC are
reported with different codes that may have different meanings.
4-24
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TABLE 4-2
A LISTING AND DESCRIPTION OF CODES USED TO INDICATE THAT POLLUTANT
CONCENTRATIONS WERE BELOW A CONCENTRATION WHICH CAN BE MEASURED
ACCURATELY OR THAT THE POLLUTANTS WERE NOT PRESENT
Definition of
P/yJpc
^^ the Acronyms
LOO-t- Limit of detection
LOQ+ Limit of quantifi-
cation
MDLf+ Method detection
limit
LT Less than
BDL Below detection
limit
<
Negative
signs
Trace*
K
ND* Not detected
Dashes*
Large
numbers*
Zeros*
Blanks*
Examples
of Use
LOD 0.421
LOQ 2.234
MDL 0.631
LT, LT 0.01
LT 0.148
BDL, BDL 0.01,
BDL 0.148
<0.01, <0.148
-0.01, -0.148
Trace, T
K0.01, K0.148
ND
—
999999
0
Used to Indicate
That the Pollutant
Was Less Than a
Limit of Detection
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Used to Indicate
That the Pollutant
Was Not Present
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
NOTES:
1. The codes, marked with a +, are the codes used when the American Chemical Society
methodology is applied.
2. The code, marked with a »•+, is the code that is used when the 40 CFR 136 methodology
is applied.
3. The Codes column lists examples of low concentration designations that may be included
in data submissions.
4. Several codes, marked with a *, have potential for being ambiguous. Their meaning
depends on laboratory reporting protocols and could either indicate that the value was
LT a limit of detection or not present.
4-25
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The following guidelines should help the enforcement officer
identify problems associated with the reporting of LT detection limit
values and prescribe remedies for future owner/operator submissions:
• GWCC should be given close attention if the LT detection limit
values appear to increase over time. Increasing detection limits
may be used to conceal an increasing concentration trend.
Table 4-3 illustrates how changing detection limits make data
interpretation difficult.
• Similarly, if background data are reported without a LT
designation at low concentrations and comparison downgradient
data are presented at higher concentrations with a LT
designation, then it is possible that LT detection limit values
are being used to conceal larger downgradient concentrations.
• It is unacceptable to report only qualitative information such as
LT for values that were measured below a limit of detection. The
enforcement officer must ensure that numerical values accompany
the LT designation so that data are available for analysis.
• LT detection limit values that are high or that vary should be
reduced in future work by laboratory procedures that remove
interfering constituents.
• The owner/operator must explain and follow the protocol for
determining and reporting low concentration values. Enforcement
officers should not allow the use of highly variable reporting
formats. Instead, the protocol used for determining and reporting
GWCC data at low concentrations should conform with the technique
described in Appendix B of 40 CFR §136 titled "Definition and
Procedure for the Determination of the Method Detection Limit-
Revision 1.11." This method is similar to the methods proposed
by the American Chemical Society.
• LT values should not be deleted from the analysis. Instead,
LT values may be analyzed at half their reported value. This
technique is simple to use and has been presented for use in
the following references:
Gilbert, R.O. and Kinnison, R.R. 1981. Statistical Methods
for Estimating the Mean and Variance from Radionuclide Data
Sets Containing Negative, Unreported, or Less than Values.
Health Physics 40:377-390.
Nehls, G.J. and Akland G.G. 1973. Procedures for Handling
Aerometric Data. Journal of the Air Pollution Control
Association 23:180-184.
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TABLE 4-3
AN EXAMPLE OF A DATA SUBMISSION WHICH MAY BE CONCEALING
AN INCREASING CONCENTRATION TREND AND/OR WHERE THE
UNITS OF MEASURE WERE REPORTED INCORRECTLY
GROUND-WATER ARSENIC CONCENTRATIONS IN PARTS PER BILLION
• August, 1982 1.54
• August, 1983 <6
• November, 1983 <11.000*
*Reported as 11 ppm.
4-27
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4.7.2 Significant Digits
All digits in a reported result that have been measured, except for
the last right-hand digit (which may have been estimated visually), are
said to contain only significant digits. Table 4-4 lists examples of data
values with their associated number of significant digits and identifies
instances in which the number of significant digits is ambiguous.
Data values for each GWCC must be reported with consistent numbers
of significant digits. Using the same number of significant digits
suggests that the constituents were measured with equal precision, subject
to the same round-off rules, and were generated and analyzed with care
and attention to detail, several extra digits should be carried through
any statistical computations that are performed.
Three ways that the number of significant digits can decrease is:
• With an order of magnitude decrease in the concentration of a
chemical species;
• Reduced precision of the analytical methodology; and
• Rounding of the values.
It is acceptable for the number of significant digits to decrease
if there has been an order of magnitude decrease in concentration, but
it is not acceptable to have a decrease in the number of significant
digits because a new analytical method with less precision has been
adopted or because significant digits have been rounded off. Sometimes
it is possible to determine that data have been rounded off by comparing
data from one sampling episode with data from another sampling episode.
Rounding should not be allowed because the number of significant digits
that are reported is related to the precision of the measurement. Round-
ing techniques should not be used to alter the apparent precision of a
measurement. Similarly, if the laboratory, chemist, data base manager,
method, or units of measure change, then the number of significant digits
4-28
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TABLE 4-4
EXAMPLES OF DATA VALUES AND THEIR ASSOCIATED NUMBER
OF SIGNIFICANT DIGITS
Number of Significant
Data Value „, .2
Digits
23,000* 2
3,437 4
567.31 5
25.01 4
1.67 3
0.30* 2
0.001** 1
0.128 3
0.120* 3
*The number of significant digits in the values with
right-hand zeros is ambiguous and without the other
values in the data set it is not possible to determine
whether the right-hand zeros were measured. In these
examples the 23,000 value is assumed to be reported to
the nearest 1000, the 0.30 is measured to the nearest
100th, and 0.120 to the nearest 1000th.
**Left hand spacing zeros in values less than one are
normally not considered as significant digits.
4-29
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may decrease. Again, a decease in precision is unacceptable and should
be corrected, correction and verification of this problem requires that
the owner/operator trace data to their earliest form which should be the
original laboratory records and laboratory technician who performed the
measurements. If rounding occurred during data processing, the data can
be corrected. However, if the chemical analysis method changed and
caused a reduction in precision, the owner/operator should be advised to
resume use of the prior methodology.
The absolute number of significant digits should be sufficient to
provide reasonable accuracy. A general rule to follow is that all of the
indicator parameters should be reported with at least three significant
digits. The importance of measuring and retaining as many significant
digits as possible is illustrated in the following example. For example,
if methylene chloride values are measured in vg/8, with two significant
digits and range from 65 to 73 then an error of plus or minus 1 yg/9.,
which is an error of one in the last significant digit, is an 11 percent
error. In contrast, if the values were measured to the tenths of a
yg/8,, that is with three significant digits, and the values ranged
from 65.1 vg/8- to "73.1 V9/1- then an error of 0.1 in the last significant
digit of 65.1 would be only about a 1 percent error. If it is difficult
operationally to measure a GWCC concentration with three significant
digits then, using the evaluation methodology described above in the
example, no more than a 10 percent error should be allowed with a one
unit change in the last significant digit of a data value.
4.7.3 Missing Data Values
Owner/operators incur a substantial risk of missing an extreme
environmental event and measurement of particularly large or small values
if they fail to collect all of the data required for a monitoring program.
This may result in an incomplete measure of environmental variability and
an increased likelihood of falsely detecting contamination. Also, if
assessment monitoring data are missing there is a danger that the full
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extent of contamination may not be characterized, owner/operators must
take extreme care to ensure that concentration measurements result from
all samples that are taken. Nevertheless, the enforcement officer is
likely to confront situations where complete detection or assessment
monitoring data have not been collected. The enforcement officer should
have the owner/operator perform the t-test despite incomplete data
collection, provided that the following criteria have been met:
• If there are data from one upgradient well and one downgradient
well, statistical comparisons should still be made. If data
exists for three quarters at a well, statistical comparisons
should be made after applying the rule described in the next
bullet.
• If only one quarter of data is missing, values should be assigned
for the four missing replicates. These values should be obtained
by averaging the values obtained during the other three quarters.
• If there are missing replicate measurements from a sampling
event, then assign values obtained by averaging the replicate(s)
which are available for that sampling event.
These guidelines have been described previously in the November 1983 EPA
memorandum on statistical analyses of indicator parameter data. The
intent of this methodology is to force use of the t-test, despite prior
noncorapliance with the data collection requirements in the regulations,
so that a determination can be made as to whether assessment monitoring
should begin. Regardless of whether there are sufficient data for
performing the t-test, the enforcement officer should consider taking
enforcement action to compel additional sampling on an accelerated
schedule (see Chapter Five of the RCRA Ground-Water Monitoring Compliance
Order Guidance). The enforcement officer must minimize delays in the
evaluation of a facility's ground water because of prior incomplete data
collection.
4.7.4 Outliers
A GWCC value that is much different than most other values in the
data for the same GWCC maybe referred to as an "outlier." The reasons
for outliers can be due to:
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• A catastrophic unnatural occurrence such as a spill;
• Inconsistent sampling or analytical chemistry methodology;
• Errors in the transcription of data values of decimal points;
and
• True but extreme GWCC concentration measurements.
The enforcement officer should attempt to have owner/operators
correct outlying values if the cause of the problem can be documented and
corrected by the owner/operator without delay. The data should be
corrected if outliers are caused by incorrect transcription and the
correct values can be obtained and documented from valid owner/operator
records. Also, if an unnatural catastrophic event or methodological
problem occurred, which can be documented, then data values should be
from calculations with clear reference to this deletion at all relevant
stages. Documentation and validation of the cause of outliers must
accompany any attempt to correct or delete data values, because true but
extreme values must not be altered. The enforcement officer should not
accept the mere presence of an extreme value in data or the effect of an
extreme value on the statistical analysis as a valid reason for the
continuation of detection monitoring.
4.7.5 Units of Measure
Associated with each GWCC value is a unit of measure which must be
reported accurately. Mistakes in the reporting of the units of measure
can result in gross errors in the apparent concentrations of GWCCs. For
example, a lead value of 30.2 might have a unit of measure of parts per
billion (ppb). Alternately, the same lead value of 30.2 might have been
incorrectly reported with a unit of measure in parts per million (ppm).
The reported value would transform to a concentration with the units of
measure in ppb as 30,200 ppb of lead or three orders of magnitude larger
than it was measured. Table 4-3 presents an example of a data submission
which included a value that was probably reported with incorrect units of
measure.
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The following guidelines should help the enforcement officer ensure
that data values are reported consistently and unambiguously:
• The units of measure should accompany each chemical parameter
name. Laboratory data sheets that include a statement "values
are reported in ppm unless otherwise noted" should generally be
discouraged but at least reviewed in detail by the enforcement
officer. It is common to find errors in reporting the units of
measure on this type of data reporting sheet.
• The units of measure for a given chemical parameter must be
consistent throughout the report.
• Finally, reporting forms for detection monitoring, as specified
in the EPA November 1983 memorandum, and the data presentation
methods described in Chapter Five should help to reduce problems
associated with the reporting of units of measure.
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CHAPTER FIVE
STATISTICAL ANALYSIS OF DETECTION MONITORING DATA
Owner/operators of hazardous waste facilities must implement a
ground-water monitoring program capable of determining if a facility has
had a significant effect on the quality of the ground water. This deter-
mination is based on the results of a statistical test. This chapter
discusses the data that should be collected to perform the statistical
test, and what actions should be taken based on the results of the
statistical test. A general description of statistical techniques is
described below. A more specific description, which includes the
computational details and an example, appears in Appendix B.
5.1 Methods for Presenting Detection Monitoring Data
Data reporting sheets such as those presented in the November 30,
1983, EPA memorandum titled "Guidance on Implementation of Subpart F
Requirements for Statistically Significant Increases in Indicator
Parameter Values" should be used when owner/operators present data as
required by §265.94(a). The enforcement official should make sure that
owner/operators are aware of and use standardized data reporting sheets.
The enforcement official should have in the file all of the ground-
water data that have been collected to date from the facility. An
explicit presentation of the statistical test methodology should also
be in the file for the facility.
5.2 Introductory Topics: Available t-Tests, Definition of Terms,
and Components of variability
Several introductory topics are discussed in this section which
pertain to the statistical analysis of detection monitoring data. First,
the statistical tests that the owner/operator can use to analyze detection
monitoring data are discussed. Then definitions of the terms background,
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upgradient, and downgradient are presented. Finally, the measurement of
environmental variability and its relationship to the number of upgradient
wells, analytical replicates, and the statistical test that should be
used is reviewed.
The interim status regulations specify that a students t-test be
used to determine whether there has been a significant increase in any
ground-water contamination indicator parameter (IP) in any well. The
§265 regulations do not, however, require a specific students t-test.
The owner/operator has the latitude within the regulations to choose a
t-test which will accommodate the data that have been collected. One
reason that interim status facilities frequently adopt the Cochran's
Approximation to the Behrens-Fisher (CABF) t-test is that the §264 permit
regulations require the use of the CABF t-test, unless an equivalent
statistical test is accepted by the Regional Administrator. Other
t-tests are available for the owner/operators to use in th malysis of
their interim status detection monitoring data. One alternative t-test,
which has been recommended for use in public comment and in the November
1983 memorandum on interim status statistical analyses, is referred to as
the averaged replicate (AR) t-test. The AR t-test is a reasonable test
for owner/operators to apply to their interim status detection monitoring
data because it removes the excessive weight that the analytical or split
sample replicates have on the background variability and may help reduce
statistically caused false positives. The owner/operator may perform the
t-test of choice, but the results must be presented and action taken
based on the results of only one type of t-test.
It should be noted that although owner/operators have latitude with
respect to the statistical test that is used, there is much less choice
with regard to the data collection requirements. Also, despite which
t-test is used the comparisons which are required to be made must not
change. A general example of the last two points is that, regardless of
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' the t-test the owner/operator has decided to use, a background data set
should be collected and compared to the data from each well individually
each time they are sampled.
i Three terms which are used frequently in discussions regarding
| the interim status detection monitoring statistical analysis are:
: background, upgradient, and downgradient. The terms upgradient and
; downgradient describe well locations (e.g., with respect to the ground-
water hydraulics) and performance (e.g., downgradient wells must be able
' to immediately detect contamination). The terms upgradient and down-
; gradient also describe the data collected from those wells. The term
: background refers to a special set of upgradient data that should have
i been collected beginning in November 1981 and ending in November 1982
' from all the wells upgradient and unaffected by the facility. In
addition, unlike references to upgradient or downgradient data which
' are well specific, references to background data concern all data
collected from all upgradient wells during the period when background
levels are being established. It may also be necessary, during the
administration of enforcement cases when background data have not been
collected properly, to require accelerated data collection and have
background data collected concomitantly with the data collected from the
downgradient wells.
The issue of the components of variability in background ground-
water data have been of concern to enforcement officials. The concern
has been that some owner/operators historically have had a tendency to
install the minimum of one upgradient well. The result is a background
data set which includes no component of spatial variability because only
one upgradient well has been sampled. Also, the background data are
influenced heavily by analytical variability because of the requirement
to obtain four measurements per sample. The split sample replicates are
valuable for ensuring that owner/operator laboratories are operating with
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a degree of quality control. However, the background data set should
also include a component of spatial variability and not be influenced
heavily by the typically small component of analytical variability.
Many owner/operators have installed a minimum, but not necessarily
acceptable, number of upgradient wells (e.g., one upgradient well). Two
recommendations are provided to help with this problem. First, the
owner/operator should install additional upgradient wells to ensure
measurement of spatial variation in the ground waters in the upgradient
area. Second, the AR t-test can be used by owner/operators to
essentially remove the excessive influence that the analytical replicate
variability has on the CABF t-test.
5.3 Statistical Analysis of the First Year's Data
As described above, owner/operators should have measured the back-
ground concentrations of ground-water parameters within one year of the
effective date of the interim status Subpart F regulations. The initial
background concentrations of the Appendix III parameters in §265.92(b)(1),
the ground-water quality parameters in §265.92(b)(2), and the ground-water
contamination (or indicator) parameters in §265.92(b)(3) should have been
established by monitoring upgradient wells quarterly for a year. Four
replicate measurements should have been obtained from each well during
each sampling episode for the indicator parameters.
The background mean and variance should have been determined using
all of the data obtained for the §265.92(b)(3) parameters during the
first year of sampling from the wells that were upgradient of the
facility. It should be noted that one primary difference between the
CABF t-test and the AR t-test is the method used to determine the
background mean and variance. These summary statistics, which describe
the background concentrations, form the basis against which all subsequent
upgradient and downgradient concentration measurements will be compared.
The methods used to estimate the background mean (X, ) and variance (s. )
b b
for the CABF and AR t-tests are described in Appendix B.
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5.4 statistical Analysis of Detection Monitoring Data After the
First Year
Detection monitoring data collected after the first year should be
used to compare with the background data to determine if there is a
suggestion that contamination may have occurred. A t-test is used to
make this determination. A significant increase in the mean concentration
of any IP in any downgradient well, that is statistically larger than the
background concentration, suggests that contamination may have occurred.
(NOTE: In the case of pH, the t-test is conducted such that an increase
or decrease is detected. All future references to significant statistical
increases imply in the case of pH that a significant statistical change
is being evaluated.)
All of the upgradient and downgradient wells must be sampled after
the first year. The ground-water quality parameters in §265.92(b)(2)
must be measured at least annually but are not analyzed statistically.
The IPs in §265.92(b)(3) must be measured in at least four replicate
measurements from each sample from each well in the detection monitoring
network at least semi-annually.
The data collected must be used to calculate an arithmetic mean
and variance at least semi-annually for each IP from each well. The
methodology for computing the mean and variance from data collected after
the first year is the same methodology used to compute the background
mean and variance.
5.4.1 Comparison of Background Data Collected the First Year With
Upgradient Data Collected in Subsequent Years
When the t-test for an upgradient well as required by §265.93(c)(1)
shows a significant increase in the concentration of an IP, there is a
suggestion that IP concentrations in the upgradient ground water may be
increasing. There are several reasons why the statistical test may
indicate that the upgradient concentrations have increased. These
include:
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• Ground-water flow direction was determined incorrectly and
hazardous waste constituents have migrated into the upgradient
wells.
• Ground-water flow direction was determined correctly, but
hazardous waste constituents are moving in a direction that is
opposite of the ground-water flow.
• Upgradient wells were located in a mound caused by the facility.
• A source of contamination unrelated to the facility was detected.
• An inconsistent methodology (e.g., well construction materials,
sampling and analysis techniques) has been used which resulted in
concentration differences that are unrelated to any change in the
concentration of IPs in the ground water.
• The t-test falsely indicated a difference between the background
data and upgradient data when actually there was no difference.
The cause of the increase in upgradient concentrations will be
important to the enforcement official if the owner/operator establishes
successfully during the first determination under assessment that no
contaminants have entered the ground water. Prior to reinstating the
detection monitoring program the owner/operator may request that, because
of the increase in background concentrations identified with the back-
ground versus upgradient comparisons, the historical data are unrepre-
sentative of background conditions and should be modified.
Several recommendations are presented which will help the enforcement
officer decide whether and how the background data set can be corrected:
• The enforcement officer should require that the owner/operator
perform the following prior to modification of the background
data. First, it must be explained exactly why the background
data set should be modified. These demonstrations must be based
upon data and considerations which are documented thoroughly.
The owner/operator must also indicate specifically how the
background data set will be modified. Finally, it must be shown
that changes in the background data will not delay the
ground-water sampling and anlaysis program.
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• Before any modifications are made to the data the enforcement
official should make sure that it is not possible to conduct the
statistical comparisons using existing data. Although some data
sets have a sparse amount of data, it may be possible to use the
recommendations in the section on missing data to impute the
values that were not collected and still make a statistical
comparison of background versus downgradient data. It may also
be possible to use data that were collected from upgradient
wells after the first year.
• Many data sets will be unusable because of unacceptable
analytical chemistry, hydrogeological considerations, or the
physical construct of the well system, for example, when
wells have been located in an area affected by the facility.
Modification of the background data set may require installation
and sampling of a new well system. In this case, it may be
necessary to require that background data from upgradient wells
be collected on an accelerated schedule concomitantly with
downgradient data.
5.4.2 Comparison of Background Data Collected During the First Year
With Downgradient Data Collected in Subsequent Years
When the t-test for a downgradient well shows a significant increase
this suggests that the facility may be affecting the ground water. The
owner/operator must immediately resample and collect multiple ground-water
samples from those downgradient wells where a significant increase in
concentration was detected as required by §265.93(c)(2). The additional
ground-water samples are to be split in two and analyzed to determine by
reapplying the t-test using the resampling data whether the significant
increase was a result of laboratory error or the result of ground-water
contamination, if the initial results are due to laboratory error and no
significant increase has occurred, the detection program may continue.
If the additional analyses performed under §265.93(c)(2) confirm the
significant increase, the owner/operator's facility is in interim status
assessment monitoring and must, without exception, begin immediately the
requirements of assessment monitoring. Ground-water contamination cannot
be evaluated satisfactorily with a continuation of detection monitoring.
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It is essential that the enforcement official determine that all
data collected from the site hydrogeologic characterization is adequate
to define the vertical and horizontal extent of the saturated zone of
potential contamination. The reliability of all phases of the site
ground-water monitoring program and the efficacy of any subsequent
corrective action efforts hinge upon the quality of the owner/operator's
site hydrogeologic characterization.
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CHAPTER SIX
ASSESSMENT MONITORING
Once the owner/operator has detected contaminant leakage via his
detection monitoring efforts, the owner/operator must undertake a more
aggressive ground-water program called assessment monitoring. Specifi-
cally, the owner/operator must determine the vertical and horizontal
concentration profiles of all the hazardous waste constituents in the
plume(s) escaping from waste management areas. In addition, the owner/
operator must establish the rate and extent of contaminant migration.
The blueprint for an assessment monitoring program is the owner/operator's
written assessment monitoring plan. This is an extremely important
document, serving several purposes:
1. It presents a detailed procedure for determining the rate of
migration, extent, and hazardous waste constituent composition
of the release.
2. It provides a mechanism for obtaining data necessary to the
permit application process, principally the §270.14(c)
information requirement.
3. It provides a mechanism for obtaining data necessary for
subsequent corrective actions at facilities.
The Agency has observed a number of problems in the way owner/
operators prepare and/or implement their assessment monitoring plans.
• Many owner/operators lack satisfactory knowledge of site
hydrogeologic conditions. As a result these owner/operators
cannot make informed decisions on how to carry out their
assessment programs. The owner/operator should have collected
abundant site hydrogeologic information prior to the installation
of the detection monitoring system in the site characterization
phase.
• Many owner/operators fail to provide enough information in
their assessment plans to allow the Agency to scrutinize their
decision-making or to evaluate their assumptions.
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• Some owner/operators fail to implement their assessment programs
quickly enough or they implement programs that will take too long
to provide information on plume extent and migration.
• Some owner/operators do not support geophysical investigation
with a sufficient monitoring well network. Geophysical methods
are valuable in confirmation of conclusions through sampling and
as in interpolative tool between wells, but they are insufficient
at present by themselves.
• Many owner/operators greatly underestimate the level of effort
the Agency expects of them in characterizing plume migration.
In most cases, assessment monitoring is an intensive effort that
will require the owner/operator to install numerous monitoring
wells. The owner/operator must track and characterize both the
horizontal and vertical components of the plume (i.e., a three
dimensional characterization).
• Many owner/operators do not follow their written plans or fail to
update their plan on the basis of information gained through
assessment programs.
For facilities in assessment monitoring the enforcement official's
main emphasis should be on (1) scrutinizing the adequacy of the owner/
operator's written assessment monitoring plan; and (2) reviewing the
owner/operator's implementation of the plan in the field.
There are a number of elements that the owner/operator should
include in the assessment monitoring plan.
• narrative discussion of the hydrogeologic conditions at the
owner/operator's site: identification of potential contaminant
pathways (Section 6.1);
• description of the owner/operator's detection monitoring system
(Section 6.2);
• description of the approach the owner/operator will use to make
the first determination (false positives rationale) (Section 6.3);
• description of the investigatory approach the owner/operator
will use to fully characterize rate and extent of contaminant
migration; identification and discussion of investigatory phases
(Section 6.4);
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• discussion of number, location and depth of wells the owner/
operator will initially install as well as strategy for
installing more wells in subsequent investigatory phases
(Section 6.5);
• information on well design and construction (Section 6.6);
• a description of the sampling and analytical program the
owner/operator will use to obtain and analyze ground-water
monitoring data (Section 6.7);
• description of data collection and analysis procedures the
owner/operator plans to employ (section 6.8); and
• a schedule for the implementation of each phase of the assess-
ment program (Section 6.9);
6.1 Description of Hydrogeologic Conditions
An owner/operator cannot conduct an adequate assessment monitoring
program without a thorough understanding of site hydrogeologic
conditions. A thorough understanding of hydrogeologic conditions,
garnered through site characterization activities (refer to Chapter One),
allows the owner/operator to identify likely contaminant pathways.
Identification of these pathways allows the owner/operator to focus
efforts on tracking and characterizing plume movement. It is important
to note that the initial site characterization carried out by the owner/
operator should provide enough hydrogeologic information to allow the
owner/operator to not only design a detection monitoring system but also
plan and carry out an assessment monitoring program. Except for cases
where some additional site information is needed (see §6.5.1), the
owner/operator should not, as part of the assessment monitoring program,
conduct hydrogeologic site characterization. This characterization
should have been completed prior to the design of detection monitoring
systems.
The owner/operator's assessment plan should describe in detailed
narrative form what hydrogeologic conditions exist at the owner/operator's
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site. The plan should describe the potential pathways of constituent
migration at the site including depth to water in aquifer, aquifer
connections to surface water and/or deeper aquifers, flow rate and
direction, and any structions such as fractures and faults which could
affect migration. The owner/operator's plan should also describe how
hydrogeologic conditions have influenced the type of assessment effort
that will be used to characterize plume migration. This portion of the
owner/operator's assessment plan should recapitulate the hydrogeologic
investigatory program the owner/operator undertook prior to installing a
detection monitoring system (see Chapter One). It should describe the
investigatory approach the owner/operator used to characterize subsurface
geology and hydrology, the nature and extent of field investigatory
activities, the results of the investigation, and explicit discussion as
to how those results have guided decisions the owner/operator has made in
regards to the planning and implementation of his assessment monitoring
program. As part of the plan, the owner/operator should append various
supporting documentation such as those described in Table 1-1.
6.2 Description of Detection Monitoring System
The owner/operator's assessment plan should describe the detection
monitoring system in place at the owner/operator's facility. Of key
concern is that the existing well system is capable of detecting all
contaminant leakage that may be escaping from the facility. If the
owner/operator's detection monitoring system is deficient either in
design or operation, plumes may escape the notice of the owner/operator.
This portion of the owner/operator's assessment plan should describe the
physical layout of the owner/operator's detection monitoring well system
(e.g., horizontal and vertical orientation of individual wells) and
identify assumptions the owner/operator used in designing the detection
monitoring system (particularly how hydrogeologic condition affected
decision making).
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6.3 Description of Approach for Making First Determination -
False Positives
Chapter Five described requirements that owner/operators must meet
in terms of statistical analysis of detection monitoring data. Once an
owner/operator has verified a statistically significant increase in
contaminant concentration in a well(s), the owner/operator must shift
from detection to assessment monitoring. Figure 6-1 illustrates the
sequence of events that occur once an owner/operator shifts to assessment
monitoring. Of particular interest are those situations where the
owner/operator feels that contamination may have been falsely indicated
and describes in his assessment plan a short term program to substantiate
or disprove the false positive claim (i.e., false positive investigation
is focus of first determination - §265.93(d)(5)).
Assessment plans focusing on substantiating a false positive claim
should only be entertained when an owner/operator's detection monitoring
system is properly designed. If an owner/operator's detection monitoring
system is inadequate, it is difficult to evaluate whether leakage has
occurred by sampling for specific constituents in the existing monitoring
network. Substantiation of a false positive claim would be a lengthy
process potentially involving hydrogeologic work, the installation of a
new detection well network and additional sampling. In those cases,
officials should reject a false positive analysis as the focus of the
first determination when the existing system is inadequate and instead
require the owner/operator to (1) correct deficiencies in the detection
monitoring system; and (2) concurrently initiate a comprehensive
assessment program downgradient from the triggering well(s).
If, however, an owner/operator's detection monitoring system is
adequately designed, the owner/operator may propose as his first
determination a short-term sampling program—generally no longer than
30 days- that will investigate whether the statistical change noted in
Part 265 indicator parameters truly represents migration of leachate into
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OWNER/OPERATOR CONDUCTS
STATISTICAL ANALYSIS - SIGNIFICANT
INCREASE INDICATED (CHANGE FOR pH)
OWNER/OPERATOR IMMEDIATELY RESAMPLES •
SIGNIFICANT INCREASE VERIFIED
T
FACILITY SHIFTS FROM DETECTION
TO ASSESSMENT MONITORING
OWNER/OPERATOR NOTIFIES REGIONAL
ADMINISTRATOR WITHIN 7 DAYS OF
VERIFYING INCREASE
i
OWNER/OPERTOR SUBMITS ASSESSMENT
PLAN WITHIN 15 DAYS OF VERIFYING
INCREASE; OWNER/OPERATOR MAKES
FALSE POSITIVE CLAIM IN ASSESSMENT PLAN
BEGINS IMMEDIATE IMPLEMENTATION
OF SHORT TERM (30 DAYS)
SAMPLING PROGRAM AS FIRST
DETERMINATION
REGIONAL ADMINISTRATOR
ENTERTAINS OWNER/OPERATOR'S
FALSE POSITIVE CLAIM IF:
• OWNER/OPERATORS DETECTION
MONITORING SYSTEM IS PROPERLY
DESIGNED; AND
• OWNER/OPERATOR ADVANCES A
SHORT TERM SAMPLING PROGRAM
WHICH FOCUSES ON APPENDIX VIII
CONSTITUENTS
f
t
CONTAMINATION CONFIRMED;
OWNER/OPERATOR BEGINS
FULL CHARACTERIZATION OF PLUME(S)
FALSE POSITIVE INDICATED;
OWNER/OPERATOR RETURNS
TO DETECTION MONITORING
FIGURE 6-1. PROCEDURE FOR EVALUATING FALSE POSITIVE CLAIMS BY OWNER/OPERATORS
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the uppermost aquifer. For units subject only to the Part 265 standards,
the short-term sampling program must, at a minimum, confirm that no
hazardous waste constituents (Appendix VII) have migrated into the
uppermost aquifer. For units subject to the Part 270 requirements
(because they are seeking an operating permit or the Agency has called
in their post-closure permit), the owner/operator should include
constituents selected from Appendix VIII in the sampling program.
After conducting the short-term sampling program (constituting the
first determination), the owner/operator must submit to the Regional
Administrator a written report describing the ground-water quality. If
the sampling program confirms that leakage has not occurred, the
owner/operator may reinstate the detection monitoring program or enter
into a consent agreement with the Agency to follow a revised detection
protocol designed to avoid future false triggers. If, however, the
short-term sampling confirms that leakage has in fact occurred, the
owner/operator must immediately begin implementation of assessment
activities to characterize rate and extent of contaminant migration.
6.4 Description of Approach for Conducting Assessment
A variety of investigatory techniques are available for use during
a ground-water quality assessment. They can be broadly categorized as
either direct or indirect methods of investigation.
All assessment programs should be designed around the direct method
of actual collection of a sample with subsequent chemical analysis to
determine actual water quality (i.e., installation of monitoring wells).
Other methods of investigation may be used when appropriate to choose the
locations for well construction. For certain aspects of an assessment,
such as defining plume location, the use of both direct and indirect
methods may be the most efficient approach.
The methods planned for use in an assessment should be clearly
specified and evaluated to ensure that the performance standard
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established for assessments can be met. Evaluating the use of direct
and indirect methods are discussed separately below.
6.4.1 Use of Direct Methods
Ground-water monitoring wells, either existing or newly installed,
are necessary to provide sampling data to establish the concentration of
hazardous constituents released from the hazardous waste management, and
the rate and extent of their migration. The owner/operator should
construct assessment monitoring wells and conduct sampling and analysis
in a manner that provides reliable data. Chapters Three and Four,
respectively, present guidance in these areas.
At facilities where it is known or suspected that volatile organics
have been released to the uppermost aquifer, organic vapor analysis of
soil gas from shallow holes may provide an initial indication of the
areal extent of the plume. To this end, the owner/operator may use an
organic vapor analyzer (OVA) to measure the volatile organic constituents
in shallow hand-augered holes. Alternatively, the owner/operator may
extract a sample of soil gas from a shallow hole and have it analyzed in
the field using a portable gas chromatograph. These techniques are
limited to situations where volatile organics are present. Further, the
presence of intervening, saturated, low permeability sediments strongly
interferes with the ability to extract a gas sample. Although it is not
necessarily a limitation, optimal gas chromatography results are obtained
when the analyte is matched with the highest resolution technique, e.g.,
electron capture/halogenated species.
Descriptions of the direct methods that will be employed during
assessment monitoring should be included in the assessment plan. These
descriptions should be sufficiently detailed to allow the method to be
evaluated and to ensure that the method will be properly executed.
6.4.2 Use of Indirect Methods
A variety of methods are currently available for identifying and, to
a limited extent, characterizing contamination in the uppermost aquifer.
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There are several geophysical techniques of potential use to an owner/
operator including electrical resistivity, electromagnetic conductivity,
ground penetrating radar, and borehole geophysics. Remote sensing and
aerial photography are additional indirect methods an owner/operator may
find useful. These techniques, with the exception of aerial photographic
methods, operate by measuring selected physical parameters in the
subsurface such as electrical conductivity, resistivity, and temperature.
The value of indirect methods is not the provision of detailed,
constituent-specific data for which they presently are clearly limited,
but rather for demarcating the general areal extent of the plume. This
is extremely important to the owner/operator for two reasons:
1. Knowing the outline of the plume before additional wells are
constructed reduces the need for speculative wells. The
assessment monitoring program therefore becomes more efficient
since well placement is guided by analytical data.
2. As the plume migrates and its margins change, the owner/operator
may track its motion and see where new wells may be needed.
There are drawbacks to the exclusive use of geophysical techniques
in assessment monitoring relating to the high level of detail necessary
to characterize the chemical composition of a ground-water plume. For
these methods to be successful in this way the contaminant(s) of interest
must induce a change in the subsurface parameter measured. This change,
in turn, must be distinguishable from ambient conditions. For example,
the electrical properties of organic hazardous constituents are generally
attenuated or masked by subsurface material properties. Unless these
constituents are present in a thick, immiscible layer, they generally
will not register during resistivity or conductivity surveys. Moreover,
nonuniform subsurface conditions may obscure low levels of certain
contaminants in ground water. Another drawback to the exclusive use of
geophysical methods at present is their inability to measure specific
concentrations of individual constituents or provide good vertical
resolution of constituent concentration. In addition, man-made struc-
tures such as powerline towers, buried pipelines, roads, and parking lots
6-9
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may interfere with the performance and reliability of may geophysical
methods. The owner/operator should therefore only use indirect methods
to guide the installation of an assessment monitoring system and to
provide an ongoing check of the extent of contaminant migration.
6.4.3 Mathematical Modeling of Contaminant Movement
Mathematical and/or computer modeling may provide information useful
to the owner/operator during assessment monitoring. The owner/operator
should not, however, depend solely on mathematical models to guide the
placement of assessment monitoring wells. The high spatial and temporal
variability of conditions encountered in the field do not lend themselves
to the simplification and assumptions necessary to model something as
highly site-specific as an assessment of the extent and rate of migration
of a contaminant plume. Furthermore, such extensive initial data is often
required as to render unclear what benefit is derived from modeling as
opposed to using direct or indirect methods.
Where a model is to be used, the owner/operator should make site-
specific measurements to verify the parameters to be used in the model.
The hydrologic parameters required to describe saturated flow include:
hydraulic conductivity (vertical and horizontal); hydraulic gradient;
specific yield (unconfined aquifer) or specific storage (confined
aquifer). The parameters required to describe contaminant flow include
the apparent velocity of the pollutant, dispersion and diffusion coeffi-
cients of the pollutants in the medium, the adsorbtion of pollutants in
the medium (retardation), and factors necessary to describe degradation
of pollutants. The dispersion coefficient is a function of the apparent
velocity and dispersivity, and cannot be directly measured unless an
extensive test with tracers Is performed. Retardation calculations are
based on soil bulk density, effective porosity and cation exchange
capacity. Retardation can also be determined from the octanol-water
partition coefficient and fractional portion of organic matter in
6-10
-------
representative volumes of soil. Degradation of pollutants depend upon
the type of constituents and the probability for chemical and biological
decay.
Background ground-water quality (e.g., indicator parameters plus
+ + + - =
Cl , Fe, Mn, Na , 804, Ca , Mg , NC>3 , PO$ , silicate, ammonium,
alkalinity or acidity) is important to determine the reactivity and
solubility of hazardous constituents in ground water and therefore is
useful in predicting their mobility under actual site conditions. The
physical and chemical characteristics of the site-specific wastes (e.g.,
density, solubility, vapor pressure, viscosity, and octanol-water
partition coefficient) and hazardous waste constituents should also be
known to reliably model constituent movement.
Mathematical models can be analytical equations by which the
hydraulic head or concentration of a contaminant at any location are
calculated. The phrase "mathematical models" is more often used to refer
to algorithms that represent the governing equations of water flow and
mass transport that can only be solved with computers. The use of
computer models enables an analysis of complex conditions that better
describe the actual environment. Any model requires the recognition of
inherent assumptions, the application of appropriate boundary conditions,
and the selection of a coherent set of input parameters.
Required parameters that can be measured directly should be
determined with consideration of selecting representative samples and
with an understanding of how input of a parameter will influence the
output (e.g., affect of assuming homogeneous conditions in a heterogeneous
environment). All parameters measured or assumed and adjusted during
model calibration should be reasonable and varied within reasonable
ranges. Modeling is not only useful in guiding direct measurements, but
can also be useful in predicting future events. When applying all
models, emphasis should be placed on the usefulness of the model to the
6-11
-------
specific problem at the site, calibration and verification with past and
present data, and careful application in the predictive mode.
A partial list of computer models that could be employed at a site
include: Modular 3-Dimensional Finite Difference Groundwater Flow Model
(USGS), to evaluate complex hydrologic conditions; computer Model of
Two-Dimensional Solute Transport and Dispersion in Ground Water (USGS) or
the Illinois State Water Survey Random Walk Solute Transport Model, to
predict contaminant transport; the AT123D model to calculate concentra-
tions isopleths for transient contaminant flow in one, two, or three
dimensions under hydraulic flow conditions; and the FEMWASTE model,
developed by Oakridge National Laboratory, which can predict contaminant
migration in both the saturated and unsaturated zones.
If an owner/operator plans to use a model to guide an assessment
monitoring program, the owner/operator must be able and willing to
describe how the model works as well as explain all assumptions used in
applying the model to the site in question.
6.5 Description of Sampling Number, Location, and Depth
The regulations require that the assessment plan specify the number,
location and depth of wells that will be installed as part of the
assessment. As the discussion on assessment methodology provided in
Section 6.4 has indicated, the owner/operator may use other sampling
techniques (e.g., indirect methods and coring) in addition to the
installation of permanent monitoring wells to augment the data generated
by wells during assessment. The owner/operator's assessment plans
should, however, specify the number, location, and depth of wells that
will be installed to characterize rate and extent of migration, and
constituent concentrations, and present explanations for the decisions.
It may not always be possible for the owner/operator to identify at
the outset of an assessment the exact number, location, and depth of all
sampling that will be required to meet the goals of an assessment. In
6-12
4
-------
many cases the investigations undertaken to characterize contamination
during an assessment will proceed in phases in which data gained in one
round of sampling will guide the next round of sampling. For example,
surface geophysical techniques can be effectively used in tandem with the
installation of monitoring wells as a first phase in the assessment
program to obtain a rough outline of the contaminant plume. Based on
these findings, a sampling program may subsequently be undertaken to more
clearly define the three-dimensional limits of the contaminant plume. In
the third phase, a sampling program to determine the concentrations of
hazardous waste constituents in the interior of the plume may be under-
taken. In this case, a detailed description of the approach that will be
used to investigate the site should be included in the assessment plan.
This description should clearly identify the number, location, and depth
of any sampling planned for the initial phase of the investigation. In
addition, the outline should clearly identify what basis will be used to
select subsequent sampling locations, including the geologic strata that
are likely to be sampled and the anticipated density of sampling. In
general, a minimum of seven well clusters should be installed to define
the extent of contamination and concentration of contaminants in the
horizontal plane (see Section 6.5.2). Each well cluster should consist
of a minimum of five wells at varing depths to profile the vertical
extent of migration (see Section 6.5.3).
6.5.1 Collection of Additional Site Information
The hydrogeologic site characterization requirements for the
detection monitoring program include:
• The subsurface geology below the owner/operator's hazardous waste
facility.
• The vertical and horizontal components of flow in the uppermost
saturated zone below the owner/operator's site.
• The hydraulic conductivity of the uppermost aquifer.
• The vertical extent of the uppermost aquifer down to the first
confining layer.
6-13
-------
If this characterization does not include all the hydrogeologic infor-
mation necessary to characterize the rate of contaminant movement, the
owner/operator should obtain this additional information for the assess-
ment phase. Examples of the additional information that may be needed to
determine the rate of contaminant movement include: mineralogy of the
materials in the migration pathway; ion exchange capacity of the material;
organic carbon content of the materials; background water quality of the
pathway (e.g., major cations and anions); the temperature of ground water
in the migration pathway; and the effective porosity of the material in
the pathway. This information will help define the transport mechanisms
which are most important at the site. All information collected during
the investigation of the plume (i.e., boring logs, core analysis, etc.)
should be recorded and the hydrogeologic descriptions of the site updated
when appropriate.
Prior to assessment well placement, a good estimation of plume
geometry can be determined from a review of current and past site charac-
terizations. For example, piezometer readings surrounding the contami-
nated detection well can be taken to determine the current hydraulic
gradient. When these values are compared to the potentiometric surface
map developed during the site investigation, the general direction of
plume migration can be approximated. Any seasonal or regional fluctua-
tions should be considered during this comparison. A review of the
facility's subsurface geology may also identify preferential pathways of
contaminant migration.
To limit drilling speculative wells, geophysical and modeling
methods can also be employed to yield a rough outline of the plume. This
expedites the assessment monitoring program. Monitoring wells can then
be strategically placed to precisely define the plume geometry.
6.5.2 Sampling Density
The program of sampling undertaken during the assessment should
clearly identify the full extent of hazardous waste constituent migration
6-14 *
C
-------
and establish the concentration of individual constituents throughout
the plume. In the initial phase of the assessment program the owner/
operator's well installation/sampling should concentrate on bounding
those areas that have been contaminated by the facility. A minimum of
seven well clusters should be installed to define the extent of contami-
nation and concentration of contaminants in the horizontal plane as
illustrated in Figure 6-2. Three well clusters should be installed in
a line downgradient from the triggering well cluster. Two of these
clusters should be installed in the plume; one cluster should be
installed beyond the plume. Four well clusters should be installed in a
line that is perpendicular to the direction of contaminant flow. Two of
these clusters should be installed in the plume, and two of these
clusters should be installed beyond the plume. This network of
monitoring wells, with a minimum of seven wells, will thoroughly define
the horizontal boundaries of the plume, and will identify and quantitate
contaminants.
The well density or amount of sampling undertaken to completely
identify the furthest extent of migration should be determined by the
variability in subsurface geology present at the site. Formations such
as unconsolidated deposits with numerous interbedded lenses of varying
permeability or consolidated rock with numerous fracture traces will
require a greater amount of sampling to ensure that all contamination is
detected.
Sampling is also required to characterize the interior of any plume
detected at the site. This is important because the migration of many
constituents will be retarded by natural attenuative processes, sampling
at the periphery of the plume may not identify all the constituents from
the facility that are reaching ground water and the concentration of
waste constituents detected at the periphery of the plume may be
significantly less than in the interior of the plume. Patterns of
concentration of individual constituents can be established throughout
6-15
-------
——i WASTE DISPOSAL UNIT BOUNDARY
CONTAMINANT PLUME
(J?) DETECTION SYSTEM WELL CLUSTER (CONTAMINATED)
X ASSESSMENT WELL CLUSTER (INITAIL)
- - FUTURE TRANSECTS OF THE PLUME (USED TO LOCATE WELL CLUSTERS
FOR FUTURE PLUME CHARACTERIZATION)
X UP GRADIENT WELL CLUSTER
FIGURE 6-2. INITIAL PLACEMENT OF WELL CLUSTERS TO DEFINE THE EXTENT OF
CONTAMINATION IN THE HORIZONTAL PLANE
6-16
-------
the plume by sampling along several lines that perpendicularly transect
the plume. The number of transects and spacing between sampling points
should be based on the size of the plume and variability in geology
observed at the site. Sampling locations should also be selected so as
to identify those areas of maximum contamination within the plume. In
addition to the expected contaminants, the plume may contain constituent
degradation products as well as reaction products.
6.5.3 Sampling Depths
The owner/operator should specify in the assessment plan the depth
at which samples will be taken at each of the planned sampling locations.
These sampling depths should be sufficient to profile the vertical distri-
bution of hazardous waste constituents at the site. Vertical sampling
should identify the full extent of vertical constituent migration.
Vertical concentration gradients including maximum concentration of each
hazardous waste constituent in the subsurface should similarly be
identified. The amount of vertical sampling required at a specific site
will depend on the thickness of the plume and the vertical variability
observed in the geology of the site. All potential migration pathways
should be sampled. The sampling program should clearly bound the
vertical extent of migration by identifying those areas on the periphery
of the plume that have not been contaminated.
In order to establish vertical concentration gradients of hazardous
waste constituents in the plume, the owner/operator must obtain a
continuous sample of the plume, which means well clusters should be
employed. The owner/operator, however, cannot know the vertical extent
of the plume; therefore, the first well in the cluster should be screened
at the horizon contamination was discovered, bearing in mind the 10-foot
screen length guidance. Additional wells in the cluster should be
screened, where appropriate, above and below the initial well's sampling
interval until the margins of the plume are established. In general,
five wells per cluster are suggested, three within the plume and one each
6-17
-------
above and below its vertical margins. Care must be taken in placing
contiguously screened wells close together since one's drawdown may
influence the next and thus change the horizon from which its samples are
drawn. Alternation of lower and higher screens should reduce this effect
(see Figure 6-3).
The specifications of sampling depths included in assessment plans
should clearly identify the interval over which each sample will be
taken. It is important that these sampling intervals be sufficiently
discrete to permit vertical profiling of constituent concentrations in
ground water at each sampling location. Sampling will only provide
measurements of the average contaminant concentration over the interval
from which that sample is taken. Samples taken from wells screened over
a large interval will be subject to dilution effects from uncontaminated
ground water lying outside the plume limits. Except for certain condi-
tions described in Chapter Two, the screened interval should be kept at
a maximum of ten feet, and in cases in which small vertical concentration
gradients are expected, smaller sampling intervals are appropriate.
A series of five wells per cluster is suggested to completely
profile the vertical boundaries of the plume. This will also enable the
identification of vertical concentration gradients and maximum
concentrations of contaminants.
As part of the progressive assessment monitoring program, the
owner/operator can use geophysical techniques to help verify the adequacy
of the placement of his assessment monitoring network. Adjustments to
the assessment monitoring program may be needed to reflect plume
migration and changes in direction.
6.6 Description of Monitoring Well Design And Construction
The monitoring well design and construction requirements for
assessment monitoring well networks are equivalent to the detection
requirements presented in Chapter Three.
6-18
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WELL
CLUSTER
NO. 1
A D8 E C
r
V
1 ^x
•IIHIIIIItMllllQI
•
" — — _ — 7Q'r-
tl
•
1
M
I
10'
•
•
1
•
II
^
s*'
1 1 1 1 1 1 1 1 • • ijj^i1 •
^^ ^*
CONTA
PL
•10' <--.
i r»'
WASTE
DISPOSAL
UNIT
GROUND-WATER
FLOW
LEGEND
WELL AND SCREEN
10' SCREEN LENGTH
IIIIH'WATER TABLE
FIGURE 6-3. VERTICAL WELL CLUSTER PLACEMENT
6-19
-------
6.7 Description of Sampling and Analysis Procedures
The owner/operator's sampling and analysis plan should be updated to
reflect the different analytical requirements of assessment monitoring.
Otherwise, the sampling and analysis plan used by the owner/operator in
his detection monitoring program (see Chapter Four) should suffice for
assessment monitoring.
The assessment plan should identify the parameters the owner/
operator will monitor for and should describe why these parameters are
suitable for determining the presence and concentration of hazardous
waste or hazardous waste constituents migrating from the facility in the
ground water. At a minimum, the owner/operator's assessment plan should
include monitoring for all hazardous waste constituents that are in the
facility's waste. Hazardous waste constituents, as defined in §260.10,
include all constituents listed in Appendix VII of Part 261, all
constituents included in Table 1 of §261.24, and any constituent listed
in Section 261.33.
Facilities that are seeking an operating permit, also have
additional plume characterization responsibilities pursuant to Part 270.
Section 270.14(c)(4) requires permit applicants to expand their
monitoring from hazardus waste constituents (primarily Appendix VII) to
the full complement of Appendix VIII constituents (Note: Appendix VII is
a subset of Appendix VIII). Therefore, when a unit is subject to the
Part 270 requirements (either because they are seeking an operating
permit or because the Agency has called in their post-closure permit),
the Agency recommends that an owner/operator's assessment plan includes
parameters that will satisfy the requirements of both Part 265 and
Part 270.
Figure 6-4 illustrates in greater detail the sampling protocol that
the Agency recommends for units that are subject to both Part 265 and
Part 270. First, the owner/operator should perform an Appendix VIII scan
€
6-20
-------
IDENTIFY HAZARDOUS
CONSTITUENTS IN
TRIGGERING WELLS
(APPENDIX VIII SCAN)
SELECT HAZARDOUS CONSTITUENTS USEFUL
IN DETERMINING RATE OF CONTAMINANT
MIGRATION AND VERTICAL AND HORIZONTAL
EXTENT OF CONTAMINANT MIGRATION
CONDUCT SAMPLING EFFORT DESCRIBED IN
ASSESSMENT PLAN, ESTABLISH GEOMETRIC
OF CONTAMINANT PLUME(S) AND RATE OF
MIGRATION OF SELECTED CONSTITUENTS
CONDUCT SAMPLING EFFORT DESCRIBED IN
ASSESSMENT PLAN; ESTABLISH VERTICAL AND
HORIZONTAL CONCENTRATION GRADIENTS OF
HAZARDOUS CONSTITUENTS IN CONTAMINANT PLUME(S)
FIGURE 6-4. SELECTION OF PLUME CHARACTERIZATION PARAMETERS
FOR UNITS SUBJECT TO PART 265 AND PART 270
6-21
-------
of samples from triggering detection monitoring wells. This scan will
provide the owner/operator with a list of hazardous constituents in the
wells which may be migrating into the uppermost aquifer. The
owner/operator should select constituents for inclusion in a sampling
program to establish geometric dimensions of the contaminant plume(s) and
the rate of migration of the plume(s). Once the owner/operator has
established the geometric dimensions of the contaminant plume(s), he
should sample for additional Appendix VIII constituents to establish
vertical and horizontal concentration gradients in the plume(s).
6.8 Procedures for Evaluating assessment Monitoring Data
The assessment plan must stipulate and document procedures for the
evaluation of assessment monitoring data. These procedures vary in a
site-specific manner but must all result in determinations of the rate of
migration, extent, and hazardous constituent composition of the contami-
nant plume. In some cases, where the release is obvious and/or chemically
simple, it may be possible to characterize it readily from a descriptive
presentation of concentrations found in monitoring wells and geophysical
characterization. In other cases, where contamination is less obvious or
the release is chemically complex, the owner/operator should employ a
statistical inference approach. Owner/operators should plan initially to
take a descriptive approach to data analysis in order to broadly delineate
the extent of contamination. Statistical comparisons of assessment moni-
toring data between wells and/or over time may subsequently be necessary
should the descriptive approach provide no clear resolution of the rate
of migration, extent, and hazardous constituent composition of the
release.
The objective of assessment monitoring is to estimate the rate and
extent of migration and the concentration of constituents in the plume.
Data are therefore collected from a set of assessment monitoring wells
that will allow characterization of the dimensions and concentrations of
€
6-22
-------
ground-water constituents (GWCCs) in the plume. In addition, compared to
detection monitoring, the number of chemical species that are analyzed in
assessment increases. Because the amount of data collected in assessment
is more voluminous than detection monitoring, the methods used to analyze
assessment monitoring data emphasize organization, data reduction,
simplification, and summary.
Assessment monitoring will include the measurement of many more
GWCC in a more extensive well network than detection monitoring. These
requirements necessitate the collection of large amounts of data during
the assessment monitoring program. Consequently, it is extremely
important for the enforcement officer to make sure that the owner/
operators specify in their assessment plans the data evaluation
procedures required by 265.93(d)(3)(iii).
Specific evaluation and reporting procedures are presented below
which the owner/operator should follow when recording and evaluating
assessment monitoring data. These procedures are used to structure,
analyze, simplify and present the ground-water monitoring data to help
the enforcement officer evaluate the extent and concentration of
ground-water contaminants. There are four evaluations or reporting
procedures that should be described in the assessment plan and that
should be used to record data in the on-site archives required by
265.94(b):
• Listing of Data
• Summary Statistics Tables
• Data Simplification
• Plotting of Data
6.8.1 Listing of the Data
A list of all the detection monitoring data and the assessment
monitoring data that have been collected should be available to
6-23
-------
enforcement officers when they review on-site records. First, data as
originally reported and verified by the analytical laboratory for those
measures requiring laboratory evaluation or as recorded in the field for
those measures collected at the time of sampling should be available to
the enforcement officer. These reporting forms should include informa-
tion which indicates that quality control samples (e.g., field and filter
blanks) were obtained in the field. Also the laboratory reporting should
indicate that both the field quality control samples were analyzed and
that the laboratory has performed and reported standard quality control
procedures performed in the laboratory (e.g., recovery analyses,
analytical replicates etc.).
The listing of GWCC concentration data should follow a format
similar to Table 6-1. The variables which should be included in the
listing are codes that identify the GWCC, well, date, unit of measure,
whether the value was LT a limit of detection and the concentration of
the GWCC. Also the listing should include the results of and codes
identifying the quality control analyses that were performed. GWCC
concentrations measured as LT a limit of detection should be indicated
and if possible the GWCC concentration that was measured should be
reported with the LT designation. Otherwise, the value that accompanies
the LT designation should be the accepted detection limit for the method
that was used. Documentation that describes the meaning of the codes
used in the listing is required to eliminate ambiguity (e.g. Pb=lead,
ppm=parts per million). The listing of GWCC data must include all
measurements from all wells since the facility began sampling, including
samples obtained during detection monitoring.
The listing should be organized to allow quick reference to specific
data values. One categorization would be to first group by GWCC, then
well code, and finally the date, as shown in Table 6-1. For example, all
lead measurements should be together, followed by all chromium measure-
ments, etc. The values for each GWCC from one well should be grouped and
f
6-24
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TABLE 6-1
AN EXAMPLE OF HOW ASSESSMENT MONITORING DATA SHOULD BE LISTED
GUCC
WELL
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD IUG/L)
LEAD (UG/L)
LEAD (UG/L)
LEAD (UG/L)
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLEHE
TRICHLOROETHYLEHE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
TRICHLOROETHYLENE
( UG/L )
I UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
( UG/L I
( UG/L I
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
( UG/L )
(UG/L)
(UG/L)
( UG/L )
( UG/L 1
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
(UG/L)
( UG/L )
( UG/L )
(UG/L)
( UG/L )
( UG/L )
I IBM
7A
7A
7A
7A
7A
9A
9A
9A
9A
9A
98
9B
9B
98
9B
9B
98
1A
U
1A
1A
1A
1A
1A
1A
1A
U
1A
10A
10A
10A
10A
10A
10A
10A
10A
10A
IDA
IDA
10A
10A
10A
10A
10A
10B
10B
10B
10B
108
10B
10B
10B
io-t
REPLICATE
1
1
1
Z
Z
1
1
Z
1
Z
I
1
Z
1
Z
ALIQUOT
DATE
LT DETECTION
CONCENTRATION UNITS
A
A
B
A
B
A
B
A
A
A
A
B
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
B
A
A
A
A
A
A
A
A
A
A
A
B
A
B
A
B
A
A
A
A
A
A
A
A
12JAN85
17FEB85
17FEB85
17FEB85
17FEB85
26APR84
26APR84
26APR84
05MAY84
05MAY84
26APR84
26APR84
26APR84
05MAY84
05MAY84
15JUN84
15JUL84
26APR84
05MAY64
15JUN84
15JUL64
15AUG84
15SEP84
160CT84
18NOV84
20DEC84
12JAN85
17FEB85
26APR84
26APR84
26APR84
05HAY84
05MAY84
1SJUN84
15AUG84
15SEP84
160CT84
18NOV84
20DEC84
12JAN85
17FEB85
17FEB8S
17FEB85
17FEB85
26APR84
26APR84
26APR84
05MAY64
05MAY84
15JUN84
15JUL84
15AUG84
t^
4
29.62
28.43
28.29
23.17
28.30
10.00
10.00
20.60
21.20
21.60
67.20
67.80
64.10
38.90
39.60
57.22
20.12
10.00
10.00
10.00
11.10
10.00
10.10
10.70
10.00
10.00
10.00
10.00
17.00
17.30
17.60
21.00
21.40
Z1.20
22.90
19.40
19.60
30.10
31.60
33.60
27.80
27.80
26.40
26.50
65.10
65.80
65.40
84.00
83.70
69.00
68.40
93.40
8:28
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
PPB
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6-25
-------
ordered by date followed by the data from the next well and so on for all
wells in the ground-water monitoring system. Alternate sortings of the
data listing may also be useful to the enforcement officer.
The data listing is not intended to function alone as an analytic
tool but the enforcement officer can use the data listing to assist in
the review of the GWCC data. First, the ordered list of data will allow
the enforcement officer quick reference to every GWCC concentration
measurement if. for example, a spurious result was found in a supporting
data analysis or report. Also, the enforcement officer can, by requiring
a consistent and orderly data listing, encourage the owner/operator to
correct many of the data quality problems, which occur frequently on
"raw" laboratory reporting sheets. Finally, data can be placed more
easily onto a State or regional computer if the data are organized and
reported consistently in a listing rather than on laboratory reporting
sheets which may have only the sample number identification rather than
well codes, dates of sampling, etc.
6.8.2 Summary Statistics Tables
The ground-water monitoring data should be summarized and presented
in tabular formats. Eight summary statistics should be calculated and
used in each of four summary tables. The eight summary statistics are:
• Number of LT detection limit values
• Total number of values
• Mean
• Median
• Standard deviation
• Coefficient of variation
• Minimum value
• Maximum value
The methodology used to estimate these summary statistics can be found in
many statistical textbooks.
6-26
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The four tables of summary statistics should include summaries by:
• GWCC summary (e.g., Table 6-2)
• GWCC summary by well (e.g., Table 6-3)
• GWCC summary by well and date (e.g., Table 6-4)
• quality control data
The tables should be formatted so that there are from one to three
columns on the left side of each table which provide data identifying,
where applicable, the GWCC, well, and date. Eight columns, one for each
summary statistic, should be to the right of the identifying columns.
There will be one row for each category that is being summarized. A
summary statistics table by GWCC, for example, will have a number of rows
equal to the number of GWCC that have been sampled. The GWCC-well table
will have a number of rows which equals the number of GWCCs measured
times the number of wells in the monitoring system (provided that each
GWCC was measured at least once in each well). The GWCC-well-date table
will be the largest table and each row should be prefixed with a GWCC,
well, and date code. The statistics in the GWCC-well-date table should
summarize all replicate sampling that was performed for each GWCC, from
each well, during each sampling.
The sample sizes, ranges, minimum, and maximum values will provide a
rapid means for checking whether errors appear in the data. It will also
facilitate rapid evaluation of GWCC concentrations over the entire
ground-water monitoring system. In addition, the summary statistics will
allow evaluation of spatial change in GWCC concentrations which include
identifying the rate and extent of migration of the GWCC plume.
The quality control data should be provided whenever assessment
monitoring data are submitted by an owner/operator. The quality control
data can be submitted in the format they are received from the laboratory
provided that all data are clearly documented. The quality control
samples taken in the field (e.g., field and sampling equipment blanks)
6-27
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may not be identified when the samples are supplied to the laboratory,
but should be identified in assessment monitoring data submissions.
Owner/operators should ensure that the laboratories provide the quality
control data that accompanies the data resulting from the analysis of
field samples.
6.8.3 Data Simplification
Ranking procedures which are described in this section are useful
for simplifying and interpreting spatial trends in GWCC concentrations by
allowing rapid determination of which wells have the overall highest and
lowest GWCC concentration. Table 6-5 presents an example of a data set
analyzed by a ranking procedure.
The ranking can be performed using the mean, median, maximum, or
minimum concentration values in the summary statistics table which
describes the values from each GWCC-well combination. For example, the
mean concentration from each well is ranked from lowest to highest for
each GWCC. The well with the lowest mean concentration of a GWCC will
receive a value of 1; the well with the next highest concentration of the
same GWCC will receive a value of 2, and so on. If two or more wells
have the identical mean concentration then the ranks for these wells will
be averaged and applied to all wells with the same mean concentration.
This procedure should be repeated for each GWCC which was detected at
least once at every well in the monitoring system. The pH values may be
ranked from highest to lowest rather than from lowest to highest
depending on whether the ground-water contamination is likely to result
in an increase or decrease in pH. It is also useful to calculate an
overall average rank for each well by averaging the ranks for each GWCC
associated with the well. These ranks should be presented in a table
using GWCCs as column headings and well codes as row headings. It is
advisable to group GWCCs with similar chemistry (e.g., volatile organics,
metals, salts, etc.) and order the rows based on the wells with spacial
6-31
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TABLE 6-5
AN EXAMPLE OF HOW RANKS OF THE MEAN CONCENTRATIONS FOR EACH
GWCC/WELL COMBINATION CAN BE USED TO SIMPLIFY AND PRESENT CONCENTRATION
DATA COLLECTED FOR A VARIETY OF QWCCs IN A NUMBER OF MONITORING WELLS
WELL RANK OF MEAN
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6-32
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proximity (e.g., upgradient, downgradient in plume, downgradient out of
plume, shallow screen depth). This will facilitate identification of
specific groups of wells where high concentrations of GWCC were detected.
6.8.4 Graphic Displays of Data
6.8.4.1 Plotting Data Over Time
Ground-water data should be plotted to allow evaluation of temporal
changes in GWCC concentrations over time. Each plot should consist of a
X or horizontal axis which represents time with year and month identified
at intervals. The Y or vertical axis should represent the concentrations
of GWCCs. The plots may be constructed using the mean values from the
GWCC-well-date summary statistics table and one plot could be presented
for each GWCC/well combination as in Figure 6-5. Alternately, it may be
more insightful to plot the data from several wells or GWCCs on one graph
provided the lines do not overlap excessively as in Figure 6-6.
Data plotting will allow the enforcement officer to evaluate changes
in GWCC concentration over time that might be due to surface hydrological
events, hydrogeology, or facility releases. In addition, insights
regarding geochemical interactions may also be revealed by examining
whether changes in some GWCCs result in expected changes in other GWCCs.
6.8.4.2 Plotting Data on Maps
It may also be useful to plot data on facility maps so that trends
in GWCCs both vertically and horizontally can be evaluated. The summary
statistics from the GWCC-well table can be used to provide data for
plotting. A map of the facility, which identifies well locations, should
be used to depict horizontal trends in concentrations. Geological cross
sections and/or facility map may be usefulfor plotting vertical trends in
GWCC concentrations. The mean concentrations can be placed near each
well location similar to the construction of potentiometric maps described
in earlier chapters. It may also be useful to plot isopleth contours of
concentration on the maps.
6-33
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6.9 Rate of Migration
An assessment plan should specify the procedures the owner/operator
will use to determine the rate of constituent migration in ground water.
A rapid approach will generally be required for determining the rate of
migration during interim status assessments. Migration rates can be
determined by monitoring the concentration of GWCCs over a period of time
in monitoring wells aligned in the direction of flow. If these wells are
located both at the edge of the plume and in the interior of the plume,
subsequent analysis of the monitoring data can then provide an accurate
determination of the rate of migration both of the contaminant front as a
whole and of individual constituents within the plume. This approach
does not necessarily provide a reliable determination of the migration
rates that will occur as the contaminant plume continues to move away
from the facility in light of potential changes in geohydrologic
conditions. More importantly, this approach requires the collection of a
time series of data of sufficient duration and frequency to gauge the
movement of contaminants. Such a delay is normally inappropriate during
initial assessment of ground-water contamination since a relatively quick
determination or at least an estimate of migration rates is required to
deduce the impact of ground-water contamination and to formulate an
appropriate reaction. Estimates of migration rates can be obtained from
aquifer properties obtained during the site investigation, and knowledge
of the physico-chemical properties of contaminants known to be present.
By recognizing the various factors which can effect transport processes
of the GWCCs, the owner/operator can obtain approximate potential
migration rates during an initial assessment phase. Continued monitoring
of the plume to verify rates of migration during assessment monitoring
established at a facility should serve as a basis for identifying
additional monitoring well locations.
Initial approximations of contaminant migration rates based on
ground-water flow rates are not reliable without verification because of
6-36
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potential differential transport rates among various classes of chemical
constituents. Differential transport rates are caused by several factors
including:
• Dispersion due to diffusion and mechanical mixing
• Retardation due to adsorption and electrostatic interactions
• Transformation due to physical, chemical, and/or biological
processes
Dispersion results in the overall dilution of the contaminant; however,
chromatographic separation of the contaminant constituents and
differential dispersal effects can result in a contaminant arriving at a
particular location before the arrival time computed solely on average
ground-water flow rates. Alternately, retardation processes can delay
the arrival of contaminants beyond that calculated by the average
ground-water flow rates. Local geology will also affect constituent
migration rates. Relating constituent migration rates to ground-water
flow rates is appropriate for a quick approximation during the initial
assessment phase, but this should be followed by a more comprehensive
study of migration rates.
Simple slug tests are not the preferred method for determining the
rate of contaminant migration. The slug test is limited to the immediate
vicinity where it is performed and its results often cannot be projected
across an entire site.
At those facilities where sufficient immiscible contaminants have
leaked to form and migrate as a separate immiscible phase (see
Figure 6-7), additional analysis will be necessary to evaluate the
migration of these contaminants away from the facility. Chapter Five
contains a discussion of the ground-water monitoring techniques that can
be used to sample multi-phased contamination. The formation of separate
phases of immiscible contaminants in the subsurface is largely controlled
6-37
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by the rate of infiltration of the immiscible contaminant and the
solubility of that contaminant in ground water, immiscible contaminants
generally have some limited solubility in water. Thus, some amount of
immiscible contaminant leaking from the facility will enter into solution
in groundwater and migrate away from the facility as dissolved
constituents. However, if the amount of immiscible reaching ground water
exceeds the ability of ground water to dissolve it, the ground water in
the upper portion of the water-table aquifer will become saturated and
the contaminant will form a separate immiscible phase.
At this point the behavior and migration of the contaminants present
in the immiscible phase will be strongly influenced by its density
relative to ground water. If the immiscibles are less dense than ground
water, the immiscibles will tend to coalesce on the surface of the water
table and form and migrate as a separate immiscible layer floating on
ground water. If the density of the immiscible contaminants is similar
to that of ground water, the immiscible will tend to mix and flow as a
separate phase with the ground water, creating a condition of multiphase
flow.
If the density of the immiscibles is greater than ground water, the
immiscibles will tend to sink in the aquifer (see Figure 6-7). As the
immiscibles sink and reach unaffected ground water in a deeper portion of
the aquifer, more of the immiscible contaminant will tend to enter into
solution in ground water and begin to migrate as dissolved constituents.
However, if enough of the dense immiscible contaminants are present, some
portion of these contaminants will continue to sink as a separate
immiscible phase until a formation of reduced permeability is reached.
At this point, these contaminants will tend to coalesce and migrate as a
layer of dense immiscibles resting on the geologic barrier.
In each of these cases, the contaminants present in the separate
immiscible phase may migrate away from the facility at rates different
6-39
-------
than that of ground water. In many cases, they will migrate at rates
slower than or equivalent to ground water, but in some cases migration
rates can be greater. In addition, migration of the immiscibles may not
be in the direction of ground-water flow. However, it is important to
reemphasize that some amount of these contaminants will invariably
dissolve in ground water and migrate away from the facility as dissolved
constituents.
Light immiscible contaminants will migrate downgradient to form a
floating layer above the saturated zone (see Figure 6-7). The slope of
the water table and the direction of ground-water flow will dictate the
movement of this light immiscible layer. Important factors involved in
its migration rate include the intrinsic permeability of the medium and
the density and viscosity of the contaminants. With time, an ellipsoidal
plume develops overlying the saturated zone as depicted in Figure 6-7.
While it is possible to analyze the behavior of the light immiscible
layer using analytical or numerical models, the most practical approach
for determining the rate and direction of migration of such a light
immiscible layer during an assessment may be to observe its behavior over
time with appropriately located monitoring wells.
The migration of a layer of dense immiscibles resting on a confining
layer may be strongly influenced by gravity. Depending on the slope of
the confining layer, the immiscible layer may move with or against the
flow of ground water. Consequently, the evaluation of the rate and
direction of migration of a dense immiscible layer is best determined by
clearly identifying the configuration of the barrier on which the layer
is migrating. The direction of migration and estimates of migration
rates can then be obtained by including the gravitational forces induced
by the slope of the confining layer in the gradients used to calculate
flow rates. A program of continued monitoring of the dense immiscible
layer should always be included in the assessment plan to verify
direction and rate of flow.
6-40
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6.10 Reviewing Schedule Of Implementation
The assessment plan should specify a schedule of implementation.
When reviewing schedules the particulars of each assessment program will
have to be considered, including the amount of work involved in the
assessment and other local factors such as weather and availability of
equipment and personnel. The schedule should include a sufficient number
of milestones so that the Agency can Judge whether sufficient progress is
being made toward the completion of the assessment during its
implementation. Any continued monitoring undertaken during the
maintenance phase of assessment should be scheduled at least on a
quarterly basis.
Activities planned to initially determine if contamination has
actually occurred should not unnecessarily delay the implementation of a
comprehensive assessment. When an extensive program to collect additional
data to remedy inadequacies in currently available data is to be under-
taken these activities should require only a short period for completion.
Additional analysis of water quality data should require no more than
fifteen days to thirty days. Sampling to determine actual concentrations
of HWC's should require only time enough for sample collection and
analysis followed by a brief period for subsequent analysis of the data.
A thorough discussion of monitoring well placement, and monitoring
well design and construction can be found in Chapters Two and Three,
respectively. A discussion of the ground-water monitoring techniques
necessary to effectively characterize a multi-phase containment migration
is also given in Chapter Four of this document.
6-41
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GLOSSARY
-------
GLOSSARY
Annular Space - The open space formed between the borehole and the well
casing.
Anticline - A fold, usually from 100 meters to 300 kilometers in width,
that is convex upward with the oldest strata at the center.
Appendix VIII Constituents - A list of 297 toxic constituents (§Part 261)
which if present in a waste may make the waste hazardous if the waste
poses a substantial hazard to human health or the environment when
improperly treated, stored, transported or disposed.
Aquiclude - A geologic formation which may contain ground water but is
incapable of transmitting significant quantitites under normal hydraulic
gradients.
Aquitard - A geologic formation of low permeability which can store or
transmit ground water in significant quantities but typically at a very
slow rate.
Assessment Monitoring - A program of monitoring under interim status
after a release to ground water has been determined wherein the rate of
migration extent and hazardous constituent concentration gradients of the
contamination must be identified.
Assessment Plan - The written detailed plan drawn up by an owner/operator
which describes and explains the procedures the owner/operator intends to
take to perform assessment monitoring.
Background Concentrations - A schedule of sampling and analysis that is
completed during the first year of monitoring. All wells in the
monitoring system must be sampled on a quarterly basis for the drinking
water suitability, ground-water quality, and contamination indicator
parameters. For each upgradient well, at least four replicate
measurements must be made for the contamination indicator parameters.
These replicate measurements must be posted and the initial background
arithmetric mean and variance calculated.
Basement - The oldest rocks recognized in a given area, a complex of
metamorphic and igneous rocks that underlies all the sedimentary
formations.
Bentonite - A sedimentary rock largely comprised of clay minerals that
have a great ability to absorb water and swell in volume.
G-l
-------
Borehole Geophysics (Geophysical Borehole Logging) - A general terra that
encompasses all techniques in which a sensing device is lowered into a
borehole for the purpose of characterizing the associated geologic
formations and their fluids. The results can be interpreted to determine
lithology, geometry resistivity, bulk density, porosity, permeability,
and moisture content and to define the source, movement, and physical/
chemical characteristics of ground water.
Coefficient of Variation - The standard deviation divided by the mean of
a set of data. (Note: the coefficient of variation can be expressed as
a percentage by multiplying the number obtained by 100).
Confined Aquifer - An aquifer under greater than atmospheric pressure
bounded above and below by impermeable layer or layers of distinctly
lower permeability (aquitard) than the aquifer itself.
Confining Layer - A geologic stratum formation exhibiting low
permeability having little or no intrinsic permeability.
Core - A continuous columnar sample of the lithologic units extracted
from a borehole. Such a sample preserves stratigraphic contacts and
structural features.
Direct Methods for Hydrogeological Investigations - Methods (e.g,
boreholes and monitoring wells) which entail the excavation or drilling,
collection, observation, and analysis of geologic materials and water
samples.
Dispersivity - Ability of a contaminant to disperse within the ground
water due to molecular diffusion and mechanical mixing.
Disposal Facility - A facility or part of a facility complex at which
hazardous waste is intentionally placed into or on any land or water,
and at which waste will remain after closure of the facility.
Downgradient - Direction of decreasing hydrostatic pressure.
Downgradient Well - A well which has been installed hydraulically
downgradient of the site, and is capable of detecting the migration of
contaminants from a regulated facility. Regulations require the
installation of three or more downgradient wells depending upon the site-
specific hydrogeological conditions and potential zones of contaminant
migration.
Drilling Mud - Fluids which are used during the drilling of a borehole or
well to wash soil uttings away from the drill bit and adjust the
specific gravity oc the liquid in the borehole so that the sides of the
hole do not cave in prior to installation of a casing.
G-2
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Electrical Resistivity (ER) - A surficial geophysical method whereby
known current is applied to spaced electrodes in the ground and the
resulting electrical resistance used to detect changes in earth materials
between and below the electrodes. ER is particularly useful for
facilities receiving electrically conductive wastes (e.g., inorganic) at
sites characterized by settings having minimal quantities of high
resistance materials.
Electromagnetic Conductivity (EM) - A surficial geophysical method
whereby induced currents are produced and measured in conductive
formations from electromagnetic waves generated at the surface. EM is
used to define shallow ground water zones characterized by high dissolved
solids content.
Floaters - Light phase organic liquids in ground water capable of forming
an immiscible layer which can float on the water table.
Flow Net - A set of intersecting equipotential lines and flow lines
representing a two-dimensional steady flow through porous media.
Fluvio-Glacial Depositional Environment - A complex melange of glacially
borne and riverine sediments deposited at the head of a melting glacier.
The sediments range in grain size from clays to boulders, and in places
are typically unsorted.
Geophysical Borehole Logging - See Borehole Geophysics.
Ground Penetrating Radar (GPR) - A geophysical method used to identify
surface formations which will reflect electromagnetic radiation. GPR
is useful for defining the boundaries of buried trenches and other
subsurface installations on the basis of time-domain reflectrometry.
Ground-Water Detection Monitoring Program - A monitoring well system
capable of yielding groundwater samples for analysis. Upgradient wells
must be installed to obtain representative background ground-water
quality in the uppermost aquifer and be unaffected by the facility.
Downgradient wells must be placed immediately adjacent to the hazardous
waste management area(s) to detect hazardous waste or hazardous waste
constituents migrating from the facility.
Hazardous Waste Constituent - A constituent listed as hazardous by EPA
based upon the criteria cited in Part 261, Subpart D, or a constituent
listed in Table 1 of §261.24.
Hazardous Waste Management - The systematic control of the collection,
source separation, storage, transportation, processing, treatment,
recovery, and disposal of hazardous waste.
G-3
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Hazardous Waste Management Area - The area within a facility's property
boundary which encompasses one or more hazardous waste management units
or cells. Detection monitoring wells should be placed on the immediate
perimeter of this area and spaced based upon the site-specific
hydrogeological characteristics.
Hydraulic Conductivity - A coefficient of proportionality which describes
the rate at which a fluid can move through a permeable medium. It is a
function of the media and of the fluid flowing through it.
Indicator Parameters - pH, specific conductance, total organic carbon
(TOC), total organic halogens (TOX).
Indirect Methods for Hydrogeological Investigations - Methods which
include the measurement or remote sensing of various physical and/or
chemical properties of the earth (e.g., electromagnetic conductivity,
electrical resistivity, specific conductance, geophysical logging, aerial
photography).
Intrinsic Permeability - Relates to the relative ease of a porous medium
to transmit liquid under a hydraulic gradient, and is independent of the
liquid itself.
Ion Exchange Capacity - Measured ability of a formation to adsorb charged
atoms or molecules.
Karst Topography - A topographic area which has been created by the
dissolution of a carbonate rock terrain. This type of topography is
characterized by sinkholes, caverns, and lack of surface streams.
Landfill - A disposal facility or part of a facility where hazardous
waste is placed in or on the land and which is not a land treatment
facility, a surface impoundment, or an injection well. A landfill should
not be used to store materials containing free liquids.
Leachate - A liquid including any suspended components in the liquid that
has percolated through or drained from hazardous waste.
Less Than Detection Limits - A phrase meaning that a chemical constituent
was either not identified or not quantified at the lowest level of
sensitivity of the analytical method being employed by the laboratory.
Therefore, the chemical constituent either is not present in the sample,
or is present but in such a small concentration it could not be measured
by the analytical procedure.
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Liner - A continuous layer of natural or man-made materials beneath or on
the sides of a surface impoundment, landfill, or landfill cell, which
restricts the downward or lateral escape of hazardous waste, hazardous
waste constituents, or leachate.
Litholoqy - The systematic description of rocks, in terms of mineral
composition and texture.
Maximum Value - In a set of data, the measurement having the highest
numerical value.
Mean - The sum of all measurements collected over a statistically
significant period of time (e.g., one year) divided by the number of
measurements.
Median - The middle point in a set of measurements ranked by numerical
value. If there are an even number of measurements, the medium is the
mean of the two central measurements.
Minimum Value - In a set of data, the measurement having the lowest
numerical value.
Mounding - A phenomenon usually created by the recharge of ground water
from a manmade structure into a permeable geologic material. Associated
ground-water flow will be away from the manmade structure in all
directions.
Number of LT Dtection Limit Values - The number of times a chemical
parameter was not detected by a given analytical procedure over a
statistically significant period of time (e.g., one year).
Octanol-Water Partition Coefficient - A coefficient representing the
ratio of solubility of a compound in octanol to its solubility in water.
As the octanol-water partition coefficient increases, water solubility
decreases.
PVC - Polyvinyl chloride.
Petrographic Analysis - Systematic description and classification of
rocks.
Phreatic Zone - See Saturated Zone.
Piezometers - Generally a small diameter, non-pumping well used to
measure the elevation of the water table or potentiometric surface.
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Potentiometrie Surface (Piezometric surface) - The surface that
represents the level to which water from a given aquifer will rise by
hydrostatic pressure. When the water-bearing zone is the uppermost
unconfined aquifer, the potentionmetric surface is identical to the water
table.
Pump Test - A test made by pumping a well for a period of time and
observing the change in hydraulic head in adjacent wells. A pump test
may be used to determine degree of hydraulic interconnection between
different water-bearing units as well as the recharge rate of a well.
Qualified Geologist - A professional (e.g., degree, experience, or
certified) specializing in the study of the earth material science.
Regional Administrator - The Regional Administrator of the appropriate
Regional Office of the Environmental Protection Agency, or the authorized
representative.
Regulated Unit - Hazardous waste management unit. The number of
regulated units will define the extent of the hazardous waste management
area.
Sampling and Analysis Plan - A detailed document describing the
procedures which will be used to collect, handle, and analyze ground-
water samples for detection or assessment monitoring parameters. The
plan should detail all quality control measures which will be implemented
to ensure sample collection, analysis, and data presentation activities
meet the prescribed requirements.
Saturated Zone (Phreatic Zone) - A subsurface zone below in which the
interstitial space of a porous medium is completely filled with water.
Seismic Prospecting - Any of the various geophysical methods for
characterizing subsurface properties based on the analysis of elastic
waves artificially generated at the surface (e.g., seismic reflection,
seismic refraction).
Shelby Tube or Split Spoon Sampler - Devices used in conjunction with a
drilling rig to obtain an undisturbed core sample of the strata.
Significant Digits - The number of digits reported in the result of a
calculation or measurement (exclusive of following zeroes).
Sinkers - Dense phase organic liquids which coalesce in an immersible
layer at the bottom of the saturated zone.
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Slug Test - An aquifer test made by either pouring a small charge of
water into a well or by withdrawing a slug of water from the well and
monitoring the length of time the well requires to return to static water
level conditions. This test is often employed to determine hydraulic
conductivity.
Standard Deviation - The positive square root of the variance. (The
variance is the average of the squares of the differences between the
actual measurements and the mean.)
Surface impoundment - A facility or part of a facility which is a natural
topographic depression, man-made excavation, or diked area formed
primarily of earthen materials (although it may be lined with man-made
materials), which is designed to hold an accumulation of liquid wastes or
wastes containing free liquids, and which is not an injection well.
Examples of surface impoundments are holding, storage, settling, and
aeration pits, ponds, and lagoons.
T-Test - The t-test is a statistical method used to determine the
significance of difference or change between sets of initial background
and subsequent parameter values.
TOG - Total organic carbon (SW-46, Method 9060).
TOX - Total organic halogens (SW-846, Method 9020).
Teflon - Tradename for polyperfluorethylene.
Total Number of Values - The number of measurements (including less than
detection values) made for a chemical parameter over a statistically
significant period of time (e.g., one year).
Tremie Method - Method whereby bentonite/cement slurries are pumped
uniformly within the annular space of a well.
Unsaturated Zone - A subsurface zone above the water table in which the
interstices of a porous medium are only partially filled with water.
Also referred to as Vadose Zone.
Upgradient - Direction of increasing hydrostatic pressure.
Upgradient Well - One or more wells which are placed hydraulically
upgradient of the site and are capable of yielding ground-water samples
that are representative of regional conditions and are not affected by
the regulated facility.
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Uppermost Aquifer - The geological formation nearest the natural ground
surface that is an aquifer, as well as all lower water-bearing units that
are hydraulically interconnected with it, and overlying or perched water-
bearing zones.
Vadose Zone - See Unsaturated Zone.
Volatile Constituents - Solid or liquid compounds which are relatively
unstable at standard temperature and pressure and undergo spontaneous
phase change to a gaseous state.
Water Table - The water level surface below the ground at which the
vadose zone ends and the phreatic zone begins. It is the level to which
a well screened in the unconfined aquifer would fill with water.
Well - A shaft or pit dug or bored into the earth, generally of a
cylindrical form, and often walled with tubing or pipe to prevent the
earth from caving in.
Well Cluster - A well cluster consists of two or more wells completed
(screened) to different depths in a single borehole or a series of
boreholes in close proximity to each other. From these wells, water
samples that are representative of the different horizons within one or
more aquifers can be collected.
Well Evacuation - Process of removing stagnant water from a well prior to
sampling.
X-Ray Diffraction - An analytical technique used to determine the
inorganic constituent content in solid materials. The sample is exposed
to x-ray radiation and the x-rays are refracted in patterns which are
characteristic of the individual inorganic constituents (e.g., NaCl).
Zone of Potential Contaminant Migration - Any subsurface formation or
layer which is permeable and would preferentially channel the flow of
contaminants away from a regulated facility.
G-8
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APPENDIX A
EVALUATION WORKSHEETS
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APPENDIX A.I
CHARACTERIZATION OF SITE HYDROGEOLOGY WORKSHEET
The following worksheets have been designed to assist the enforcement
official in evaluating the program the owner/operator used in characterizing
hydrogeologic conditions at his site. This series of worksheets has been
compiled to parallel the information presented in Chapter 1 of the TEGD.
I. Review of Site Hydrogeologic Investigatory Techniques
A. Was the site investigation and/or data collection
performed by a qualified geologist? (Y/N)_
B. Did the owner/operator survey the following existing
regional data:
1. U.S.G.S. Maps? (Y/N).
2. Water supply well logs? (Y/N).
3. Other (specify)
C. Did the owner/operator use the following direct
techniques in the hydrogeologic assessment:
1. Soil borings/rock corings? (Y/N)_
2. Materials tests (e.g., grain size analyses,
standard penetration tests, etc.)? (Y/N)_
3. Piezometer installation for water level
measurements at different depths? (Y/N)_
4. Slug tests? (Y/N)
5. Pump tests? (Y/N)]
6. Geochemical analyses of soil samples? (Y/N)_
7. Other (specify)
D. Did the owner/operator use the following indirect
techniques to supplement direct techniques data:
1. Geophysical well logs? (Y/N).
2. Tracer studies? (Y/N)[
3. Resistivity and/or electromagnetic conductance? (Y/N)
4. Seismic Survey? (Y/N)
5. Hydraulic conductivity measurements of cores? (Y/N)
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6. Aerial photography?
7. Ground penetrating radar?
8. Other (specify)
E. Did the owner/operator document and present the
raw data from the site hydrogeologic assessment?
F. Did the owner/operator document methods (criteria)
used to correlate and analyze the information?
G. Did the owner/operator prepare the following:
1. Narrative description of geology?
2. Geologic cross sections?
3. Geologic and soil maps?
4. Boring/coring logs?
5. Structure contour maps of aquifer and aquitard?
6. Narrative description of ground-water flows?
7. Water table/potentiometric map?
8. Hydrologic cross sections?
H. Did the owner/operator obtain a regional map of the
area and delineate the facility?
I. If yes, does this map illustrate:
1. Surficial geology features?
2. Streams, rivers, lakes, or wetlands near the facility?
3. Discharging or recharging wells near the facility?
J. Did the owner/operator obtain a regional
hydrogeologic map?
K. If yes, does this hydrogeologic map indicate:
1. Major areas of recharge/discharge?
2. Regional ground-water flow direction?
3. Potentiometrie contours which are consistent with
observed water level elevations?
L. Did the owner/operator prepare a facility site map?
M. If yes, does the site map show:
1. Regulated units of the facility (e.g., landfill
areas, impoundments)?
2. Any seeps, springs, streams, ponds, or wetlands?
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N).
(Y/N).
(Y/N).
(Y/N)
(Y/N)
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Location of monitoring wells, soil borings,
or test pits? (Y/N).
How many regulated units does the facility have?
If more than one regulated unit then,
• Does the waste management area encompass all
regulated units? (Y/N).
Or
• Is a waste management area delineated for each
regulated unit? (Y/N).
II. characterization of Subsurface Geology of site
A. Soil boring/test pit program:
1. Were the soil borings/test pits performed under
the supervision of a qualified professional? (Y/N).
2. Were the borings placed 300 feet apart? (Y/N).
3. If not, did the owner/operator provide documentation
for selecting the spacing for borings? (Y/N)_
4. Were the borings drilled to the depth of the first
confining unit below the uppermost zone of
saturation or ten feet into bedrock? (Y/N).
5. Indicate the method(s) of drilling:
• Auger (hollow or solid stem)
• Mud rotary
• Air rotary
• Reverse rotary
• Cable tool
• Jetting
• Other (specify)
6. Were continuous sample corings taken? (Y/N)
7. How were the samples obtained (check method[s])
• Split spoon
• Shelby tube, or similar
• Rock coring
• Ditch sampling
• Other (explain)
8. Were the continuous sample corings logged by a
qualified geologist? (Y/N).
9. Does the field boring log include the following
information:
• Hole name/number? (Y/N).
• Date stared and finished? (Y/N)]
• Geologist's name? (Y/N)_
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Driller's name? (Y/N).
Hole location (i.e., map and elevation)? (Y/N)_
Drill rig type and bit/auger size? (Y/N).
Gross petrography (e.g., rock type) of
each geologic unit? (Y/N).
Gross mineralogy of each geologic unit? (Y/N).
Gross structural interpretation of each (Y/N).
geologic unit and structural features
(e.g., fractures, gouge material, solution
channels, buried streams or valleys,
identification of depositional material)? (Y/N).
Development of soil zones and vertical extent
and description of soil type? (Y/N).
Depth of water bearing unit(s) and vertical
extent of each? (Y/N).
Depth and reason for termination of borehole? (Y/N)
Depth and location of any contaminant encountered
in borehole? (Y/N).
Sample location/number? (Y/N).
Percent sample recovery? (Y/N).
Narrative descriptions of:
— Geologic observations? (Y/N).
-- Drilling observations? (Y/N).
10. Were the following analytical tests performed on the
core samples:
• Mineralogy (e.g., microscopic tests and x-ray
diffraction)? (Y/N).
• Petrographic analysis:
- degree of crystallinity and cementation of
matrix? (Y/N).
- degree of sorting, size fraction (i.e.
sieving), textural variations? (Y/N)_
- rock type(s)? (Y/N)_
- soil type? (Y/N)_
- approximate bulk geochemistry? (Y/N)
- existence of microstructures that may effect
or indicate fluid flow? (Y/N)_
Falling head tests? (Y/N).
Static head tests? (Y/N).
Settling measurements? (Y/N).
Centrifuge tests? (Y/N)_
Column drawings? (Y/N)_
B. Verification of subsurface geological data
1. Has the owner/operator used indirect geophysical methods
to supplement geological conditions between borehole
locations? (Y/N)
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2. Does the number of borings and analytical data indicate
that the confining layer displays a low enough
permeability to impede the migration of contaminants
to any stratigraphically lower water-bearing units?
3. Is the confining layer laterally continuous across
the entire site?
4. Did the owner/operator consider the chemical
compatibility of the site-specific waste types
and the geologic materials of the confining layer? (Y/N)
5. Did the geologic assessment address or provide
means for resolution of any information gaps of
geologic data? (Y/N)
6. Does the laboratory data corroborate the field
data for petrography? (Y/N)
7. Does the laboratory data corroborate the field
data for mineralogy and subsurface geochemistry? (Y/N)
C. Presentation of geologic data
1. Did the owner/operator present at least four
geologic cross sections of the site? (Y/N)
2. Do each of these cross sections:
• identify the types and characteristics of
the geologic materials present?
• define the contact zones between different
geologic materials?
• note the zones of high permeability or
fracture?
• give detailed borehole information including:
— location of borehole? (Y/N)
— depth of termination? (Y/N)
— location of screen (if applicable)? (Y/N)
— depth of zone of saturation? (Y/N)
3. Did the owner/operator provide a topographic map which
was constructed by a licensed surveyor? (Y/N)
4. Does the topographic map provide:
• contours at a maximum interval of two-feet? (Y/N)
• locations and illustrations of man-made
features (e.g., parking lots, factory
buildings, drainage ditches, storm drains,
pipelines, etc.)? (Y/N)
descriptions of nearby water bodies? (Y/N)
descriptions of off-site wells? (Y/N)
site boundaries? (Y/N)
individual RCRA units? (Y/N)
delineation of the waste management area(s)? (Y/N)
well and boring locations? (Y/N)
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5. Did the owner/operator provide an aerial photo-
graph depicting the site and adjacent off-site
features? (Y/N).
6. Does the photograph clearly show surface water
bodies, adjacent municipalities, and residences
and are these clearly labelled? (Y/N)_
III. Identification of Ground-Water Flowpaths
A. Ground-water flow direction
1. Was the well casing height measured by a
licensed surveyor to the nearest 0.1 feet?
2. Were the well water level measurements taken
within a 24 hour period?
3. Were the well water level measurements taken
to the nearest 0.1 feet?
4. Were the well water levels allowed to stabilize
after construction and development for a
minimum of 24 hours prior to measurements? (Y/N)_
5. Was the water level information obtained
from (check appropriate one):
• multiple piezometers placement in single
boreholes?
• vertically nested piezometers in closely spaced
separate boreholes?
6. Did the owner/operator provide construction
details for the piezomete's? (Y/N).
7. How were the static water levels measured (check
method(s).
Electric water sounder
- Wetted tape
- Air line
- Other (explain)
Was the well water level measured in wells
drilled to an equivalent depth below the
saturated zone, or screened at an equivalent
depth below the saturated zone? (Y/N).
Has the owner/operator provided a site water table
(potentiometric) contour map? If yes, (Y/N)_
• Do the potentiometric contours appear logical
based on topography and presented data?
(Consult water level data) (Y/N).
• Are ground-water flowlines indicated? (Y/N).
• Are static water levels shown? (Y/N).
• Can hydraulic gradients be estimated? (Y/N).
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10. Did the owner/operator develop two, or more,
hydrologic cross sections of the vertical flow
component across the site? (Y/N)
11. Do the owner/operator's flow nets include:
• piezometer locations? (Y/N).
• depth of screening? (Y/N)_
• width of screening? (Y/N)_
B. Seasonal and temporal fluctuations in ground-water level
1. Do fluctuations in static water levels occur? (Y/N)
• If yes, are the fluctuations caused by any of
the following:
— Off-site well pumping (Y/N).
— Tidal processes or other intermittent natural
variations (e.g., river stage, etc.) (Y/N).
— On-site well pumping (Y/N)
— Off-site, on-site construction or changing
land use patterns (Y/N).
— Deep well injection (Y/N).
— Seasonal variations (Y/N)
— Other (specify)
2. Has the owner/operator documented the source and
patterns that contribute to or affect the ground-water
patterns below the waste management (Y/N)
3. Do the water level fluctuations alter the general
ground-water gradients and flow directions? (Y/N).
4. Based on water level data, do any head differ-
entials occur that may indicate a vertical flow
component in the saturated zone? (Y/N).
5. Did the owner/operator implement means for gauging
long term effects on water movement that may result
from on-site or off-site construction or changes
in land-use patterns? (Y/N).
C. Hydraulic conductivity
1. How were hydraulic conductivities of the subsurface
materials determined?
• Single-well tests (slug tests)? (Y/N).
• Multiple-well tests (pump tests)? (Y/N).
2. If single-well tests were conducted, was it done
by:
- Adding or removing a known volume of water, (Y/N)
Or
- Pressurizing well casing (Y/N)_
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3. IE single well tests were conducted in a highly
permeable formation, were pressure transducers
and high-speed recording equipment used to
record the rapidly changing water levels? (Y/N)_
4. Since single well tests only measure hydraulic
conductivity in a limited area, were enough
tests run to ensure a representative measure
of conductivity in each hydrogeologic unit? (Y/N)_
5. Is the owner/operator's slug test data
(if applicable) consistent with existing
geologic information (e.g., boring logs)? (Y/N).
6. Were other hydraulic conductivity properties
determined? (Y/N).
7. If yes, provide any of the following data, if
available:
• Transmissivity
• Storage coefficient
• Leakage
• Permeability
• Porosity
• Specific capacity
• Other (specify)
D. Identification of the uppermost aquifer
1. Has the extent of the uppermost saturated zone
(aquifer) in the facility area been defined? If yes, (Y/N).
• Are soil boring/test pit logs included? (Y/N).
• Are geologic cross-sections included? (Y/N).
2. Is there evidence of confining (competent,
unfractured, continuous, and low permeability)
layers beneath the site? (Y/N).
• If yes, was continuity demonstrated through the
evidence of lack of drawdown in the upper well
when separate, closely-spaced wells (one screened
at the uppermost part of the water table, and
the other screened on the lower side of the
confining layer) are pumped simultaneously? (Y/N).
3. Was hydraulic conductivity of the confining unit
determined to be less than 10~7 cm/sec through
direct field measurements? (Y/N).
4. Does potential for other hydraulic interconnect-
tion exist (e.g., lateral incontlnuity between
geologic units, facies changes, fracture zones,
cross cutting structures, or chemical corrosion/
alteration of geologic units by leachate)? (Y/N).
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IV. Conclusions
A. Subsurface geology
1. Has sufficient data been collected to adequately
define petrography and petrographic variation? (Y/N)
2. Has the subsurface geochemistry been adequately
defined? (Y/N).
3. Was the boring/coring program adequate to define
subsurface geologic variation? (Y/N)
4. Was the owner/operator's narrative description
complete and accurate in its interpretation
of the data? (Y/N).
5. Does the geologic assessment address or provide
means to resolve any information gaps? (Y/N)_
B. Ground-water flowpaths
1. Did the owner/operator adequately establish the
horizontal and vertical components of ground-
water flow? (Y/N).
2. Were appropriate methods used to establish
ground-water flowpaths? (Y/N)
3. Did the owner/operator provide accurate
documentation? (Y/N)
4. Are the potentiometric surface measurements
valid? (Y/N).
5. Did the owner/operator adequately consider the
seasonal and temporal effects on the ground-
water? (Y/N).
6. Were sufficient hydraulic conductivity tests
performed to document lateral and vertical
variation in hydraulic conductivity in the
entire hydrogeologic subsurface below the
site? (Y/N)_
C. Uppermost aquifer
1. Did the owner/operator adequately define the
uppermost aquifer? (Y/N)_
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APPENDIX A.2
PLACEMENT OF DETECTION MONITORING WELLS WORKSHEET
The following worksheets are designed to assist the enforcement officer's
evaluation of an owner/operator's approach for selecting the number, location,
and depth of all detection phase monitoring wells. This series of worksheets
has been compiled to closely track the information presented in Chapter 2 of
the TEGD. The guide for the evaluation of an owner/operator's placement of
monitoring wells is highly dependent upon a thorough characterization of the
site hydrogeology as described in Chapter 1 of the TEGD and Appendix A.I
worksheets.
I. Placement of Downgradient Detection Monitoring Wells
A. Are the ground-water monitoring wells or clusters located
immediately adjacent to the waste management area? (Y/N)_
B. How far apart (i.e., what is the spacing?) between detection
monitoring well locations?
Does the owner/operator provide a rationale for the
location of each monitoring well or cluster? (Y/N)
Does the owner/operator provide an explanation for the
spacing of the ground-water monitoring wells? (Y/N)
Has the owner/operator identified the vertical sampling
interval(s) of each monitoring well or cluster, i.e.,
depth and thickness? (Y/N).
Does the owner/operator provide an explanation for the
depth and thickness of the vertical sampling interval(s)
for each monitoring well or cluster? (Y/N)
What length screens has the owner/operator employed in
the ground-water monitoring wells on site?
H. Does the owner/operator provide an explanation for the
screen length(s) chosen? (Y/N)_
I. Do the actual locations of monitoring wells or clusters
correspond to those identified by teh owner/operator? (Y/N)_
A2-1
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II. Placement of Upgradient Monitoring Wells
A. Has the owner/operator documented the location of each
upgradient monitoring well or cluster? (Y/N)
B. Does the owner/operator provide an explanation for the
location(s) of the upgradient monitoring wells? (Y/N)
C. Has the owner/operator provided a rationale for the
depth and thickness of the vertical sampling interval
for each background monitoring well or cluster? (Y/N)_
D. What length screens has the owner/operator employed in
the background monitoring well(s)?
E. Does the owner/operator provide an explanation for the
screen length(s) chosen? (Y/N)
F. Does the actual location of each background monitoring
well or cluster correspond to that identified by the
owner/operator? (Y/N).
III. Conclusions
A. Downgradient Wells
Do the location, spacing, and vertical sampling interval(s)
of the ground-water monitoring wells or clusters in the
detection monitoring system allow the immediate detection
of a release of hazardous waste or constituents from the
hazardous waste management area to the uppermost aquifer? (Y/N)
B. Upgradient Wells
Do the location and vertical sampling interval(s) of the
upgradient (background) ground-water monitoring wells
ensure the capability of collecting ground-water samples
representatiave of upgradient (background) ground-water
quality including any ambient heterogeneous chemical
characteristics? (Y/N)
A2-2
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APPENDIX A.3
MONITORING WELL DESIGN AND CONSTRUCTION WORKSHEET
The following worksheets have been designed to assist the enforcement
officer in evaluating the techniques used by an owner/operator for designing
and constructing monitoring wells. This series of worksheets has been
compiled to parallel the information presented in Chapter 3 of the TEGD.
I. Monitoring Well Design
A. Complete the attached well construction summary sheet for the
monitoring well unless similar documentation is already available
from the owner/operator. Include the locations where the well
intercepts changes in geological formation.
II. Drilling Methods
A. What drilling method was used for the well?
• Hoilow-stem auger
• Solid-stem auger
• Mud rotary
• Air rotary
• Reverse rotary
• Cable tool
• Jetting
• Air drill with casing hammer
• Other (specify)
B. Were any cutting fluids (including water) or additives
used during drilling? (Y/N).
If yes, specify
Type of drilling fluid
Source of water used
Foam
Polymers
Other
C. Was the cutting fluid, or additive, analyzed? (Y/N)_
D. Was the drilling equipment steam-cleaned prior to drilling
the well? (Y/N)_
E. Was compressed air used during drilling? (Y/N)
1. If yes, was the air treated to remove oil (e.g.,
filtered)? (Y/N)
A3-1
-------
MOJCCT
sire _
DATE COMPLETED
BY _
WELL NO.
AOUIFIE* -
ELEVATION
X
&
«
c
«t
Elevation of reference point
Height of reference point
Mirfac*
tkpth of »wrf«c«
Type of »urf«et M«1
1.0. of »wrf«e« C«tin9
Type of turfact easing:
Depth of »urf«e« casing
l.O. of ris«r pipt
Typ« of riMr pipt:
I • 0i«««t«r of bortholt
-\m - Typt of fill.r:
CltV*tiOA /
Type of M«l:
of tOP Of M«l
Typ* of grav* I pack
Cl«v./4«ptn of top of
Elevation / tftpth of top of tcr»«n
Description of screen _______
I.S. of screen section
Elevation / depth of bottom of screen
. /depth of bottom of gravel pack
E lev. /depth of bottom of plugged
blank section
Type of filler below plugged
section
Elevation of DOT cor* of
Well Construction Suasary.
A3-2
-------
F. Did the owner/operator document procedure for establishing
the water table? (Y/N),
1. If yes, how was the location established?
G. Formation samples
1. Were continuous formation sample cores collected during
drilling? (Y/N).
2. How were the samples obtained?
• Split spoon
• Shelby tube
• Core drill
• Other (specify)
3. Indicate the frequency at which formation samples were
collected
4. Identify if any physical and/or chemical tests were per-
formed on the formation samples (specify)
III. Monitoring Well Construction Materials
List of Potential Construction Materials for the Saturated Zone
1. Stainless steel (316)
2. Teflon
A. Identify construction materials (by number) and diameters
(ID/OD)
Diameter
Material (ID/OD)
1. Primary Casing
2. Secondary or outside casing
(double construction)
3. Screen
B. How are the sections of casing and screen connected?
• Pipe sections threaded
• Couplings (friction) with adhesive or solvent
• Couplings (friction) with retainer screws
• Other (specify)
C. Were the materials steam-cleaned prior to installation? (Y/N)_
A3-3
-------
IV. Well Intake Design and Well Development
A. Was a well intake screen installed? (Y/N)_
1. What is the length of the screen for the well?
2. Is the screen manufactured? (Y/N).
B. Was a filter pack installed? (Y/N).
1. Has a turbidity measurement of the well water ever
been made? (Y/N)_
C. Well development
1. What technique was used for well development?
• Surge block
• Bailer
• Air surging
• Water pumping
• Other (specify)
V. Annular Space Seals
A. Is the annular space in the saturated zone directly above
the filter pack filled with?
• Sodium bentonite (specify type and grit)
• Cement (specify neat or concrete)
• Other (specify)
1. Was the seal installed by?
• Dropping material down the hole and tamping
• Dropping material down the inside of
hollow-stem auger
• Tremie pipe method
• Other (specify)
B. Was a different seal used in the unsaturated zone? (Y/N)
If yes,
1. Was this seal made with?
• Sodium bentonite (specify type and grit)
• Cement (specify neat or concrete)
• Other (specify)
2. Was this seal installed by?
• Dropping material down the hole and tamping
• Dropping material down the inside of
hollow-stem auger
• Tremie pipe method
• Other (specify)
C. Is the upper portion of the borehole sealed with a concrete
cap to prevent infiltration from the surface? (Y/N)
A3-4
-------
D. Is the well fitted with an above-ground protective device? (Y/N)
E. Has the protective cover been installed with locks to
prevent tampering? (Y/N)
VI. Field Tests/Field Demonstration
A. Do field measurements of the following agree with
reported data:
1. Casing diameter? (Y/N).
2. Well depth? (Y/N).
3. Water level elevation? (Y/N).
B. If the existing well is being field demonstrated, complete
Questions 1 through 7.
1. Is the location of the demonstration well hydraulically
equivalent to the existing well? (Y/N).
2. Was the demonstration well installed using EPA-approved
methods and materials? (Y/N)_
3. How were the wells evacuated (e.g., bailer or bladder
pump)?
existing well:
demonstration well:
4. Were the wells sampled concurrently? (Y/N)
5. Were the wells each sampled using the appropriate EPA
methodology? (Y/N).
6. What parameters were the ground water samples analyzed
for?
7. Are the values for these parameters equivalent for each
well (i.e., within the acceptable standard deviations)? (Y/N).
VII. Conclusions
A. Do the design and construction of the owner/operator's
ground-water monitoring wells permit depth discrete ground-
water samples to be taken? (Y/N)
B. Are the samples representative of ground-water quality? (Y/N).
C. Are the ground-water monitoring wells structurally stable? (Y/N).
D. Does the ground-water monitoring well's design and con-
struction permit an accurate assessment of aquifer
characteristics? (Y/N)
A3-5
-------
APPENDIX A.4
SAMPLING AND ANALYSIS WORKSHEET
The following worksheets have been designed to assist the enforcement
officer in evaluating the techniques an owner/operator uses to collect and
analyze ground-water samples. This series of worksheets have been compiled
based on the information provided in Chapter 4 of the TEGD.
I. Review of Sample Collection Procedures
A. Measurement of well depths elevation:
1. Are measurements of both depth to standing water
and depth to the bottom of the well made? (Y/N)_
2. Are measurements taken to the nearest centimeter
or 0.1 feet? (Y/N).
3. What device is used?
4. Is there a reference point established by a licensed
surveyor? (Y/N).
B. Detection of immiscible layers:
1. Are procedures used which will detect light phase
immiscible layers? (Y/N).
2. Are procedures used which will detect heavy phase
immiscible layers? (Y/N).
C. Sampling of immiscible layers:
1. Are the immiscible layers sampled separately prior to
well evacuation? (Y/N).
2. Do the procedures used minimize mixing
with water soluble phases? (Y/N)_
D. Well evacuation:
1. Are low yielding wells evacuated to dryness? (Y/N)
2. Are high yielding wells evacuated so that at least
three casing volumes are removed? (Y/N).
3. What device is used to evacuate the wells?
4. If any problems are encountered (e.g., equipment
malfunction) are they noted in a field logbook? (Y/N)_
E. Sample withdrawal:
1. For low yielding wells, are samples for volatiles, pH,
and oxidation/reduction potential drawn first after
the well recovers? (Y/N)
A4-1
-------
10.
11,
12.
13.
14.
Are samples withdrawn with either Teflon or stainless
steel (316) sampling devices? (Y/N)_
Are sampling devices either bottom valve bailers
or positive gas displacement bladder pumps? (Y/N)
If bailers are used, is "Teflon"-coated wire, single
strand stainless steel wire, or monofilament used to
raise and lower the bailer? (Y/N).
If bladder pumps are used, are they operated in a
continuous manner to prevent aeration of the sample? (Y/N)_
If bailers are used, are they lowered slowly to
prevent degassing of the water? (Y/N)
If bailers are used, are the contents transferred
to the sample container in a way that will minimize
agitation and aeration? (Y/N)
Is care taken to avoid placing clean sampling equipment
on the ground or other contaminated surfaces prior to
insertion into the well? (Y/N).
If dedicated sampling equipment is not used, is
equipment disassembled and thoroughly cleaned between
samples? (Y/N).
If samples are for inorganic analysis, does the clean-
ing procedure include the following sequential steps:
a. Dilute acid rinse (HNO3 or HC1)? (Y/N).
b. Distilled/deionized water rinse? (Y/N).
If samples are for organic analysis, does the cleaning
procedure include the following sequential steps:
a. Nonphosphate detergent wash? (Y/N).
b. Tap water rinse? (Y/N).
c. Distilled/deionized water rinse? (Y/N).
d. Acetone rinse? (Y/N)
e. Pesticide-grade hexane rinse? (Y/N)_
Is sampling equipment thoroughly dry before use? (Y/N).
Are equipment blanks taken to ensure that sample
cross-contamination has not occurred? (Y/N).
If volatile samples are taken with a positive gas
displacement bladder pump, are pumping rates below
100 ml/min? (Y/N)
F. In-situ or field analyses:
1. Are the following labile (chemically unstable) parameters
determined in the field:
a. pH? (Y/N).
b. Temperature? (Y/N).
c. Specific conductivity? (Y/N).
d. Redox potential? (Y/N).
e. Chlorine? (Y/N).
f. Dissolved oxygen? (Y/N).
g. Turbidity? (Y/N).
h. Other (specify)
A4-2
-------
For in-situ determinations, are they made after well
evacuation and sample removal? (Y/N)
If sample is withdrawn from the well, is parameter
measured from a split portion? (Y/N)
Is monitoring equipment calibrated according to
manufacturers' specifications and consistent with
SW-846? (Y/N).
Is the date, procedure, and maintenance for equipment
calibration documented in the field logbook? (Y/N).
II. Review of Sample Preservation and Handling Procedures
A. Sample containers:
1. Are samples transferred from the sampling device
directly to their compatible containers? (Y/N).
2. Are sample containers for metals (inorganics) analyses
polyethylene with polypropylene caps? (Y/N)
3. Are sample containers for organics analysis glass
bottles with Teflon-lined caps? (Y/N).
4. If glass bottles are used for metals samples are
the caps Teflon-lined? (Y/N).
5. Are the sample containers for metal analyses cleaned
using these sequential steps?
a. Nonphosphate detergent wash? (Y/N)
b. 1:1 nitric acid rinse? (Y/N).
c. Tap water rinse? (Y/N).
d. 1:1 hydrochloric acid rinse? (Y/N).
e. Tap water rinse? (Y/N).
f. Distilled/deionized water rinse? (Y/N)_
6. Are the sample containers for organic analyses cleaned
using these sequential steps?
a. Nonphosphate detergent/hot water wash? (Y/N)_
b. Tap water rinse? (Y/N)_
c. Distilled/deionized water rinse? (Y/N)_
d. Acetone rinse? (Y/N)_
e. Pesticide-grade hexane rinse? (Y/N)_
7. Are trip blanks used for each sample container type
to verify cleanliness? (Y/N)_
B. Sample preservation procedures:
1. Are samples for the following analyses cooled to 4°C:
a. TOC? (Y/N)_
b. TOX? (Y/N)~
c. Chloride? (Y/N)_
d. Phenols? (Y/N)_
e. Sulfate? (Y/N)~
f. Nitrate? (Y/N)
A4-3
-------
g. Coliform bacteria?
h. Cyanide?
i. Oil and grease?
j. Hazardous constituents (§261, Appendix VIII)?
2. Are samples for the following analyses field acidified
pH <2 with HNO3:
a. Iron?
b. Manganese?
c. Sodium?
d. Total metals?
e. Dissolved metals?
f. Fluoride?
g. Endrin?
h. Lindane?
i. Methoxychlor?
j. Toxaphene?
k. 2,4 D?
1. 2,4,5, TP Silvex?
m. Radium?
n. Gross alpha?
o. Gross beta?
3. Are samples for the following analyses field acidified
to pH <2 with H2SO4:
a. Phenols?
b. Oil and grease?
4. Is the sample for TOC analyses field acidified to
pH <2 with HC1?
5. Is the sample for TOX analysis preserved with
1 ml of 1.1 M sodium sulfite?
6. Is the sample for cyanide analysis preserved with
NaOH to pH >12?
C. Special handling considerations:
1. Are organic samples handled without filtering?
2. Are samples for volatile organics transferred to
the appropriate vials to eliminate headspace over
the sample?
3. Are samples for metal analysis split into two
portions?
4. is the sample for dissolved metals filtered
through a 0.45 micron filter?
5. Is the second portion not filtered and analyzed
for total metals?
6. Is one equipment blank prepared each day of
ground-water sampling?
(Y/N)
(Y/N)
(Y/N)
(Y/N)
to
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N)
A4-4
-------
III. Review of Analytical Procedures
A. Laboratory analysis procedures:
1. Are all samples analyzed using an EPA-approved
method (SW-846)? (Y/N).
2. Are appropriate QA/QC measures used in laboratory
analysis (e.g., blanks, spikes, standards)? (Y/N).
3. Are detection limits and percent recovery (if
applicable) provided for each parameter? (Y/N)
4. If a new analytical method or laboratory is used,
are split samples run for comparison purposes? (Y/N)
5. Are samples analyzed within specified holding
times? (Y/N).
B. Laboratory logbook:
1. Is a laboratory logbook maintained? (Y/N)
2. Are experimental conditions (e.g., temperature,
humidity, etc.) noted? (Y/N)_
3. If a sample for volatile analysis is received
with headspace, is this noted? (Y/N)_
4. Are the results for all QC samples identified? (Y/N)]
5. Is the time, date, and name of person noted
for each processing step? (Y/N)_
IV. Review of Chain-of-Custody Procedures
A. Sample labels:
1. Are sample labels used? (Y/N).
2. Do they provide the following information:
a. Sample identification number? (Y/N).
b. Name of collector? (Y/N).
c. Date and time of collection? (Y/N).
d. Place of collection? (Y/N)]
e. Parameter(s) requested and preservatives used: (Y/N)
3. Do they remain legible even if wet? (Y/N)
B. Sample seals:
1. Are sample seals placed on those containers to
ensure the samples are not altered? (Y/N)
C. Field logbook:
1. Is a field logbook maintained? (Y/N).
2. Does it document the following:
a. Purpose of sampling (e.g., detection or
assessment)? (Y/N)
b. Location of well(s)? (Y/N)
c. Total depth of each well? (Y/N)]
d. Static water level depth and measurement
technique? (Y/N)
A4-5
-------
e. Presence of immiscible layers and
detection method?
f. Collection method for immiscible layers
and sample identification numbers?
g. Well evacuation procedures?
h. Sample withdrawal procedure?
i. Date and time of collection?
j. Well sampling sequence?
k. Types of sample containers and sample
identification numbers?
1. Preservative(s) used?
m. Parameters requested?
n. Field analysis data and method(s)?
o. Sample distribution and transporter?
p. Field observations?
• unusual well recharge rates?
• Equipment malfunction(s)?
• Possible sample contamination?
• Sampling rate?
q. Field team members?
D. Chain-of-custody record:
1. Is a chain-of-custody record included with
each sample?
2. Does it document the following:
a. Sample number?
b. Signature of collector?
c. Date and time of collection?
d. Sample type?
e. Station location?
f. Number of containers?
g. Parameters requested?
h. Signatures of persons involved in the
chain-of-possession?
i. Inclusive dates of possession?
E. Sample analysis request sheet:
1. Does a sample analysis request sheet accompany
each sample?
2. Does the request sheet document the following:
a. Name of person receiving the sample?
b. Date of sample receipt?
c. Laboratory sample number (if different than
field number)?
d. Analyses to be performed?
F. Laboratory logbook:
1. Is a laboratory logbook maintained?
2. If so, does it document the following:
a. Sample preparation techniques (e.g., extraction)?
b. Instrumental methods?
c. Experimental conditions?
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N).
(Y/N)
(Y/N).
(Y/N).
(Y/N)
(Y/N)
(Y/N)
A4-6
-------
V. Review of Quality Assurance/Quality Control
A. Is the validity and reliability of the laboratory and
field generated data ensured by a QA/QC program? (Y/N)
B. Does the QA/QC program include:
1. Documentation of any deviations from approved
procedures? (Y/N).
2. Documentation of analytical results for:
a. Blanks? (Y/N).
b. Standards? (Y/N).
c. Duplicates? (Y/N).
d. Spiked samples? (Y/N).
C. Are approved statistical methods used? (Y/N)
D. Are QC samples used to correct data? (Y/N)
E. Are all data critically examined to ensure it
has been properly calculated and reported? (Y/N)
VI. Review of Indicators of Data Quality
A. Reporting of low and zero concentration values:
1. Do specific concentration values accompanying
measurements reported as less than a limit of
detection? (Y/N).
2. is the magnitude of detection limits consistent
throughout the data set for each parameter? (Y/N)
3. Have techniques described in Appendix B of
40 CFR §136 been used to determine the detection
limits? (Y/N).
4. Has the method for using less than detection
limit data in presentations and statistical
analysis been documented? (Y/N)_
B. Significant digits:
1. Are constituent concentrations reported with
a consistent number of significant digits? (Y/N)_
2. Are all indicator parameters reported with
at least three significant digits? (Y/N)_
C. Missing data values:
1. Is the monitoring data set complete? (Y/N)
2. Are t-test comparisons between upgradient and
downgradient wells attempted despite missing
data provided that:
a. At least one upgradient and one downgradient
well were sampled? (Y/N)
A4-7
-------
b. In the case of a missing quarterly
sampling set, values are assigned by
averaging corresponding values for
the other three quarters? (Y/N)_
c. In the case of missing replicate values
from a sampling event, values are assigned
by averaging the replicate(s) which are
available for that sampling event? (Y/N).
D. Outliers:
1. Have extreme values (outliers) of constituent
concentrations deleted or otherwise modified
because of:
a. Incorrect transcription? (Y/N).
b. Methodological problems or an unnatural
catastrophic event? (Y/N).
c. Are these above occurrences fully
documented? (Y/N).
2. Are true but extreme values unaltered and
incorporated in the analysis? (Y/N)_
E. Units of measure:
1. Are all units of measure reported accurately? (Y/N)
2. Are the units of measure for a given chemical
parameter used consistently throughout the
report? (Y/N),
3. Do the reporting formats clearly indicate
consistent units of measure throughout so that
no ambiguity exists (i.e., do the units
accompany each parameter instead of a
statement, "all values are ppm unless
otherwise stated")? (Y/N)
VII. Conclusions
A. Does the sampling and analysis plan permit the owner/
operator to detect and, where applicable, assess the
nature and extent of a release of hazardous constituents
to ground water from the monitored hazardous waste
management facility? (Y/N).
A4-8
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APPENDIX A. 5
PRESENTING DETECTION MONITORING DATA WORKSHEET
The following worksheets have been designed to assist the enforcement
official in evaluating the method an owner/operator uses in presenting and
statistically analyzing detection monitoring data. This series of worksheets
has been compiled to parallel the information provided in Chapter 5 of the
TEGD.
I. Presenting Detection Monitoring Data
A. Is the owner/operator using the reporting sheets
as described in the TEGD (Chapter 5)? (Y/N).
B. Have all the detection monitoring data collected by the
facility been obtained and reviewed? (Y/N).
II. T-test and Number of Wells
A. Which t-test is in use:
1. Cochran's approximation to the Behrens-Fisher
(CABF t-test)?
2. Averaged replicate t-test (AR t-test)?
3. Other, describe:
B. Does the facility have more than one upgradient monitoring
well? (Y/N)
III. First Year's Data
A. Have upgradient wells been monitored to establish background
concentrations of the following data on a quarterly basis for
one year:
1. Appendix III parameters (§265.92(b)(1))? (Y/N)_
2. Ground-water quality parameters (§265.92(b)(2))? (Y/N).
3. Ground-water contamination indicator parameters
(S265.92(b)(3)>? (Y/N).
B. Were four replicate measurements obtained from each
upgradient well during the first year of quarterly detec-
tion monitoring for indicator parameters [§265.92(b)(3)]? (Y/N)
C. Have the background mean and variance been determined for
the §265.92(b)(3) parameters using all the data obtained
from the upgradient wells during the first year of sampling? (Y/N)_
A5-1
-------
IV. Subsequent Year's Data
A. Is monitoring data collected after the first year being
compared with background data to determine possible
groundwater contamination? (Y/N)
B. Is the identified approved t-test being used properly to
determine possible ground-water contamination? (Y/N)
C. Are the ground-water quality parameters in §265.92(b)(2)
being measured at least annually? (Y/N)
D. Are the indicator parameters in §265,92(b)(3) being
measured in at least four replicate samples from each
well in the detection monitoring network at least
semi-annually? (Y/N).
E. Are the indicator parameters collected on a semi-annual
basis being used to estimate the mean and variance? (Y/N)_
F. Is the elevation of the water table at each monitoring
well determined each time a sample is collected? (Y/N).
V. Conclusions
A. Is the owner/operator adequately reporting and statis-
tically analyzing the facility's monitoring well data? (Y/N).
B. If the t-test indicated a significant incease in IP's for
downgradient wells, were they resampled and reanalyzed? (Y/N).
C. If the resampling still indicated a significant increase,
was assessment monitoring begun? (Y/N).
A5-2
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APPENDIX A.6
ASSESSMENT MONITORING
The following worksheets have been designed to assist the enforcement
officer in evaluating an owner/operator's assessment phase ground-water
monitoring program. This series of worksheets has been compiled to parallel
the information presented in Chapter 6 of the TEGD.
I. Review of Hydrogeologic Descriptions
A. Has the site's hydrogeologic setting been well characterized
(refer to Appendix A.I of TEGD)? (Y/N).
1. Has the regional and local hydrogeologic setting
been thoroughly described? (Y/N).
2. Is there sufficient direct field information? (Y/N).
3. Is the information accurate and reliable? (Y/N).
4. Was the evaluation performed by a hydrogeologist? (Y/N)_
5. Did indirect investigatory methods correlate with
direct methods? (Y/N).
6. Have all possible migration pathways been identified? (Y/N).
7. Will the description of the hydrogeologic setting aid
in characterizing the rate and extent of the plume
migration? (Y/N).
II. Review of Detection Monitoring System Description
A. Is the detection monitoring system capable of detecting
all contaminant leakage that may be escaping from the
facility (refer to Appendix A.2 of TEGD)? (Y/N).
1. Are the well designs and construction parameters
fully documented? (Y/N).
2. Have the downgradient wells been strategically
located so as to intercept migrating contaminants? (Y/N)
3. Are upgradient wells positioned so that they are
not effected by the facility? (Y/N),
4. Are the screened intervals 10 feet or less? (Y/N)"
5. Are the well construction materials (e.g., casing,
screen, seals, pacxing) comprised of material that
will not affect the ground-water quality? (Y/N).
III. Review of Description of Approach for Making First Determination
A. Did the detection monitoring system consistently yield
statistically equivalent concentrations for all indicator
parameters? (Y/N).
A6-1
-------
If no:
1. Were the results based on the Student's t-test at the
0.01 level of significance? (Single-tailed t-test for
testing significant increases and two-tailed t-test
for testing significant differences in pH values.) (Y/N)
2. Were the calculations performed correctly? (Y/N)
3. If the results are deemed as a false positive, did
the owner/operator fully document the reasoning? (Y/N).
4. Is there any reasonable cause to believe that faulty
data are responsible for the false positive claim? (Y/N)
5. Can or will deficiencies in well design, sample
collection, sample preservation, or analysis be
corrected? (Y/N).
6. If the owner/operator intends to collect additional
data to remedy any inadequacies, will this collection
result in an acceptable delay in assessing the extent
of contamination at the site? (Y/N).
7. will positive results of these determinations initiate
a drilling program for assessment monitoring? (Y/N)
IV. Review of Approach for Conducting Assessment
A. Have the assessment monitoring objectives been clearly
defined in the assessment plan?
1. Does the plan include analysis and/or re-evaluation
to determine if significant contamination has occurred
in any of the detection monitoring wells?
2. Does the plan provide for a comprehensive program of
investigation to fully characterize the rate and
extent of contaminant migration from the facility?
3. Does the plan call for determining the concentrations
of hazardous wastes and hazardous waste constituents
in the ground water?
4. Does the plan employ a quarterly monitoring program?
B. Does the assessment plan identify the investigatory
methods that will be used in the assessment phase?
1. Is the role of each method in the evaluation fully
described?
2. Does the plan provide sufficient descriptions of the
direct methods to be used?
3. Does the plan provide sufficient descriptions of the
indirect methods to be used?
4. Will the method contribute to the further characteri-
zation of the contaminant movement?
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
A6-2
-------
C. Are the investigatory techniques utilized in the assess-
ment program based on direct methods? (Y/N)
1. Does the assessment approach incorporate indirect
methods to further support direct methods? (Y/N)
2. Will the planned methods called for in the assessment
approach ultimately meet performance standards for
assessment monitoring? (Y/N)
3. Are the procedures well defined? (Y/N).
4. Does the approach provide for monitoring wells similar
in design and construction as the detection monitoring
wells? (Y/N).
5. Does the approach employ taking samples during drill-
ing or collecting core samples for further analysis? (Y/N)
D. Are the indirect methods to be used based on reliable
and accepted geophysical techniques? (Y/N).
1. Are they capable of detecting subsurface changes
resulting from contaminant migration at the site? (Y/N).
2. Is the measurement at an appropriate level of
sensitivity to detect ground-water quality changes
at the site? (Y/N).
3. Is the method appropriate considering the nature
of the subsurface materials? (Y/N)
4. Does the approach consider the limitations of
these methods? (Y/N).
5. Will the extent of contamination and constituent
concentration be based on direct methods and sound
engineering judgment? (Using indirect methods to
further substantiate the findings) (Y/N).
E. Does the assessment approach incorporate any mathematical
modeling to predict contaminant movement? (Y/N)
1. Will site specific measurements be utilized to
accurately portray the subsurface? (Y/N)_
2. Will the derived data be reliable? (Y/N)"
3. Have the assumptions been identified? (Y/N).
4. Have the physical and chemical properties of the
site-specific wastes and hazardous waste constituents
been identified? (Y/N)
V. Review of Assessment Monitoring Wells
A. Does the assessment plan specify:
1. The number, location, and depth of wells? (Y/N)
2. The rationale for their placement and identify the
basis that will be used to select subsequent sampling
locations and depths in later assessment phases? (Y/N)
A6-3
-------
B. Does the assessment period consist of a phased investiga-
tion so that data gained in initial rounds may help guide
subsequent rounds?
1. Do initial rounds incorporate geophysical techniques
to approximate the limits of the contaminant plume?
2. Has information from the triggering well (well show-
ing elevated contaminant concentrations) been incor-
porated in the initial design and specifications?
3. Is the sampling program designed adequately to portray
a three dimensional plume configuration?
4. Are evaluation procedures in place that will provide
further guidance for subsequent monitoring?
C. Does sufficient hydrogeologic data exist in the direction
of the contaminant plume?
1. Does the subsurface setting provide any information
on possible transport mechanisms and attenuation
processes?
2. Are provisions made to secure additional data as
needed?
3. Are hydrogeologic descriptions updated as additional
data become available?
D. Sampling density:
1. Are a minimum of seven well clusters installed?
2. Are the well clusters placed both perpendicular and
parallel to plume migration from the triggering well?
3. Are the well clusters placed both inside and outside
the contaminant plume to identify its horizontal
boundaries?
4. Are sampling locations situated so as to identify
areas of maximum contaminant concentration within
the plume?
5. Does the sampling density correlate with the size
of the plume and the geologic variability?
E. Sampling depths:
1. Are the intervals over which the samples are collected
clearly identified?
2. Are the well screens within each cluster positioned
to sample the full extent of the predicted vertical
distribution of hazardous waste constituents?
3. Are the well screens depth discrete to the extent
possible to minimize dilution effects?
4. Are there a minimum of five wells per cluster?
• Are at least three wells screened within the plume?
• Are at least two wells screened above and below
the plume, respectively?
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N).
(Y/N)
(Y/N)
(Y/N).
(Y/N)
A6-4
-------
Are the wells placed alternating lower and higher
screened wells to reduce the effect of drawdown on
the sampling horizons? (Y/N)
Are there high fluctuations in ground-water levels,
or is the subsurface characterized by fractured
consolidated formations that may otherwise require
screen lengths greater than 10 feet? (Y/N).
Are the wells screened to identify vertical concen-
tration gradients and maximum concentrations of the
contaminants? (Y/N)
VI. Review of Monitoring Well Design and Construction
A. Are the well design and construction specification require-
ments equivalent to the detection requirements detailed in
Chapter 3? (Y/N).
B. Are well design and construction details provided for:
1. Drilling methods? (Y/N).
2. Well construction materials? (Y/N).
3. Well diameter? (Y/N).
4. Well intake structures and procedures for well
development? (Y/N).
5. Placement of annular seals? (Y/N).
C. Are all these details approved and recommended considering
the characteristics of the site? (Y/N)
VII. Review of Sampling and Analysis Procedures
A. Does the list of monitoring parameters include all
hazardous waste constituents from the facility? (Y/N).
1. Does the water quality parameter list include other
important indicators not classified as hazardous
waste constituents? (Y/N).
2. Does the owner/operator provide documentation for
the listed wastes which are not included? (Y/N).
B. Have the procedures been detailed for sample collection? (Y/N).
1. Do the procedures include evacuation of the borehole
prior to sample collection? (Y/N).
2. Are special procedures delineated for collection of
separate phase immiscible contaminants? (Y/N).
3. Has the equipment been identified? (Y/N).
4. Do the procedures include decontamination of equipment? (Y/N)
5. Have pumping rates, duration, and position in the well
from which water will be evacuated been specified? (Y/N)_
A6-5
-------
C. Do the procedures include provisions for sample preser-
vation and shipment?
D. Do the procedures specify:
1. Type of sample containers?
2. Filtering procedures?
3. Preservation techniques?
4. Storage and time elements involved?
5. Proper documentation?
E. Do these procedures correspond to recommended procedures
(SW-846 or EPA-approved procedures) for sampling and
1 preservation?
F. Do the sampling and analysis procedures identify analyti-
cal procedures for each of the identified monitoring
parameters?
G. Do the analytical procedures include:
1. Detailed description and reference of approved
analytical methods?
2. QA/QC procedures?
3. Location of laboratory performing analysis?
4. Proper documentation?
Does the sampling and analysis plan establish procedures
for chain of custody control?
Do these procedures include:
1. Sample labels?
2. Sample seals?
3. Field logbook?
4. Chain of custody record?
5. Sample analysis request sheet?
6. Laboratory logbook?
J. Do the procedures specify how assessment monitoring data
will be evaluated to determine if contamination has
actually occurred?
1. Will the evaluation delineate the full extent of
contaminant migration?
2. Will significant changes in containment concentration
or movement be identified?
3. Are the evaluation procedures suitable and objective?
K. Does the assessment plan clearly describe the procedures
that will be used for evaluating monitoring data during
the assessment?
L. Does the plan provide for evaluation of its methodologies
to ensure each method is properly executed during the
assessment period?
H.
I.
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N).
(Y/N)
(Y/N)
(Y/N)
(Y/N)
(Y/N)
A6-6
-------
M. Is a list of all detection monitoring and assessment monitor-
ing (if applicable) data available from the owner/operator? (Y/N)
1. Do these lists include:
• Field quality control samples (e.g., sample container
and equipment blanks)? (Y/N).
• Laboratory quality control samples (e.g., replicates,
spiked samples, etc.)? (Y/N).
2. Are the lists prepared using a format which presents:
Codes that identify GWCCs? (Y/N).
Well number? (Y/N).
Date? (Y/N).
Units of measure? (Y/N).
Less than (LT) detection limit values? (Y/N).
Concentrations of GWCCs? (Y/N).
N. Has the owner/operator prepared summary statistics tables
of the GWCC data? (Y/N).
1. Do the summary statistics tables include:
Number of LT detection limit values? (Y/N).
Total number of values? (Y/N).
Mean? (Y/N).
Median? (Y/N).
Standard deviation? (Y/N).
Coefficient of variation? (Y/N).
Minimum value? (Y/N).
Maximum value? (Y/N).
re there summary statistics tables that present:
GWCC? (Y/N).
GWCC by well number? (Y/N).
GWCC by well number and date? (Y/N)_
Quality control data? (Y/N).
O. Has the owner/operator simplified the statistical data? (Y/N).
1. Was the data simplified using a ranking procedure for
each GWCC-well combination? (Y/N).
2. Has the ranking procedure been applied to each GWCC
which was detected at least once at every well in the
monitoring system? (Y/N)
P. Did the owner/operator display the data graphically? (Y/N)
1. Were the data plotted graphically to evaluate
temporal changes? (Y/N)_
2. Were the data plotted on facility maps to evaluate
spacial trends? (Y/N).
VIII. Review of Migration Rates
A. Did the owner/operator's assessment plan specify the pro-
cedures to be used to determine the rate of constituent
migration in the ground-water?
(Y/N)
A6-7
-------
B. Do the procedures incorporate a periodic re-evaluation of
sampling data to continually monitor the rate and extent
of contaminant migration? (Y/N)
1. Do the procedures clearly establish ground-water flow
rates and direction downgradient from the detection
wells? (Y/N).
2. Are the methods employed suitable for these determina-
tions? (Y/N).
3. Are the limitations of these methods known and
documented? (Y/N).
4. Do the evaluations incorporate chemical and physical
characteristics of the contaminants and the media? (Y/N).
5. Are adsorptive and degradative processes considered
in determining any retardation of contaminant movement? (Y/N).
6. Have the assumptions been identified and documented? (Y/N).
C. Does the assessment plan evaluate the presence of
immiscible phase layers? (Y/N).
1. Do the procedures specify detection and collection
of light and dense phase immiscibles prior to well
evacuation? (Y/N).
2. Has the owner/operator used the slope of the water
table and the velocity of ground-water flow to estimate
light phase immiscible migration? (Y/N).
3. Has the owner/operator defined the configuration of
the confining layer to predict dense phase immiscible
migration?- (Y/N).
IX. Reviewing Schedule of Implementation
A. Has the owner/operator specified a schedule of implementa-
tion in the assessment plan? (Y/N).
B. Does the schedule for implementing assessment monitoring
data include a timetable for a comprehensive site evalua-
tion for contamination? (Y/N).
C. Does the timetable include:
1. A number of milestones used to judge if sufficient
progress is being made toward the completion of the
assessment during implementation? (Y/N).
2. The determination if contamination has occurred? (Y/N).
3. Completing an initial comprehensive assessment of
contamination at the site? (Y/N).
4. Implementing a program for continued monitoring after
fully characterizing contamination at the site? (Y/N).
D. Does this represent an acceptable time frame? (Y/N),
A6-8
-------
X. Conclusions
A. Has the owner/operator adequately characterized site
hydrogeology to determine contaminant migration? (Y/N)
B. Is the detection monitoring system adequately designed
and constructed to immediately detect any contaminant
release? (Y/N).
C. Are the procedures used to make a first determination of
contamination adequate? (Y/N)
D. Is the assessment plan adequate to detect, characterize,
and track contaminant migration? (Y/N)
E. Will the assessment monitoring wells, given site hydro-
geologic conditions, define the extent and concentration
of contamination in the horizontal and vertical planes? (Y/N)
F. Are the assessment monitoring wells adequately designed
and constructed? (Y/N).
G. Are the sampling and analysis procedures adequate to
provide true measures of contamination? (Y/N).
H. Do the procedures used for evaluation of assessment
monitoring data result in determinations of the rate of
migration, extent of migration, and hazardous constituent
composition of the contaminant plume? (Y/N)
I. Are the data collected at sufficient duration and frequency
to adequately determine the rate of migration? (Y/N)
J. Is the schedule of implementation adequate? (Y/N)
K. Is the owner/operator's assessment monitoring plan adequate? (Y/N).
1. If the owner/operator had to implement his assessment
monitoring plan, was it implemented satisfactorily? (Y/N)
A6-9
-------
APPENDIX B
METHODOLOGY AND EXAMPLE APPLICATIONS THAT DESCRIBE THE USE OF
COCHRAN'S APPROXIMATION TO THE BEHRENS-FISHER AND
THE AVERAGED REPLICATE T-TESTS
-------
BACKGROUND
This appendix presents t-test methodologies that may be used by
owner/operators to analyze interim status detection monitoring ground-
water data. The 40 CFR §265 Subpart F regulations require that owner/
operators use a students t-test to determine whether individual wells in
the monitoring network contain any indicator parameter concentrations
which are statistically greater than background concentrations measured
during the first year of sampling. Several different t-tests can be
constructed to analyze interim status detection monitoring data and
during interim status, an owner/operator may choose a t-test which is
found to be most applicable to the data being analyzed. However, owner/
operators must understand that for interim status facilities enforcement
officers will only accept one t-test methodology, which must be documented
with explicit examples and technical references.
Two suggested t-test methodologies are presented in this appendix.
Cochran's Approximation to the Behrens-Fisher (CABF) t-test and a t-test
termed the Averaged Replicate (AR) t-test. These tests are described
with the following organization: an introduction, methodology used to
analyze the first year's data, and methodology used to analyze data
collected after the first year. After presentation of the methods an
example is analyzed using the CABF and AR methods.
COCHRAN'S APPROXIMATION TO THE BEHRENS-FISHER T-TEST
Introduction
The methodology for the CABF is presented for several reasons.
First, the CABF test is referenced explicitly in the 40 CFR §264 permit
regulations. Prior guidance has directed use of the CABF t-test. The
CABF t-test is also widely documented and presented in many statistical
textbooks as a t-test for use when two groups of unpaired data with
different variances are under comparison. Although the CABF t-test has
been criticized widely because it may not match well with the ground-
water data collected by interim status facilities, it will be described
because it is presently being used by interim status facilities.
B-l
-------
Methodology Used to Analyze the First Year's Data
Data collected during the first year from the upgradient wells are
used to estimate the background mean and variance. All of the data
collected from the upgradient wells must be used. If sampling were more
frequent than quarterly or if multiple upgradient wells yielded data then
all of these data should be included in the background mean and variance.
The background mean (Xb) for the CABF t-test is:
"b °b Pb
Xb " I I I Xijk/Nb
i=l j=l k=l
= Background concentration measurement from the ith well,
the jth sampling period, and the kth replicate measurement,
Where 1=1 to nb, j=l to ob, and k=l to pb.
Nb = Number of background measurements.
2
The background variance (s ) for the CABF t-test is:
2 nb °b Pb 2
s = I I I (Xijk - Xb) /Nb-l
b i=l j=l k=l
Methodology Used to Analyze Data Collected After the First Year
The data for each parameter from each monitoring well, from each
sampling event (upgradient and downgradient wells) after the first year
must be compared individually with the background data collected during
the first year. Four replicate measurements should be taken from each
well for each indicator parameter (IP) during every semi-annual sampling
event. These monitoring data are used to calculate a mean and variance
for every IP at every monitoring well each time the well system is sampled.
B-2
-------
The mean (Xm) for monitoring well m for the CABF test is:
Pm
k=l
where: X^ = the kth replicate measurement from the mth
monitoring well. Where k=l to pm.
Nm = number of replicate measurements from
monitoring well m.
2
The variance (s ) for monitoring well m for the CABF test is:
m
2 P"> _ 2
s = £
-------
The critical t-statistic (tr) is calculated as follows:
where: V. = s. /N.
b b b
W. t. + W t
_ b b T m m
C W. + W
b * m
W = s /N
m mm
tfc = The critical value from Table B-l with (N^-l) degrees
of freedom.
tra = The critical value from Table B-l with (Nm-l) degrees
of freedom.
(NOTE: If pH is being tested use the two-tailed critical values,
otherwise use the one-tailed critical values).
The t* is then compared with t using the following decision rules:
• If specific conductivity, TOC, and TOX are being evaluated and if
t* is less than t then there is no statistical indication that
c
the IP concentrations are larger in the well under comparison than
in the background data. If t* is larger than t then there is a
statistical indication that IP concentrations are larger in the
well under comparison.
• If pH is being evaluated and if |t*| (which is the absolute
value of t* or t* without a + or - sign) is less than t then
there is no statistical indication that pH has changed. If
|t*| is larger than t then there is an indication that pH
has changed statistically. If t* is negative then pH increased if
t* is positive pH decreased.
B-4
-------
TABLE B-l
ONE AND TWO TAILED CRITICAL t VALUES AT THE
.01 LEVEL OF SIGNIFICANCE
Degrees of
Freedom One Tailed Two Tailed
1 31.821 62.657
2 6.965 9.925
3 4.541 5.841
4 3.747 4.604
5 3.365 4.032
6 3.143 3.707
7 2.998 3.499
8 2.896 3.355
9 2.821 3.250
10 2.764 3.169
11 2.718 3.106
12 2.618 3.055
13 2.650 3.012
14 2.642 2.977
15 2.602 2.947
16 2.583 2.921
17 2.567 2.898
18 2.552 2.878
19 2.539 2.861
20 2.528 2.845
21 2.518 2.831
22 2.508 2.819
23 2.500 2.807
24 2.492 2.797
25 2.485 2.787
26 2.479 2.779
27 2.473 2.771
28 2.467 2.763
29 2.462 2.756
30 2.457 2.750
40 2.423 2.704
60 2.390 2.660
120 2.358 2.617
2.326 2.576
Adapted from Table III, Statistical Tables for
Biological, Agricultural, and Medical Research,
Fisher and Yates, 1949.
B-5
-------
AVERAGED REPLICATE T-TEST
Introduction
The averaged replicate (AR) t-test methodology is presented for
several reasons. First, the AR t-test has been suggested for use in
public comment and was recommended subsequently for use in a memorandum
from Skinner in November, 1983. Also, the AR t-test removes the heavy
influence that split sample or replicate variability exerts on the overall
estimate of variability in the background data. It has been suggested
that the AR t-test may help alleviate statistical contributions to the
problem of incorrect indication of contamination.
Methodology Used to Analyze the First Year's Data
Similar to the CABF t-test the background mean and variance must be
calculated. This is done by first averaging the replicate measurements
and then using these replicate averages to calculate the background mean
and variance as described below.
Background Mean:
Pb
^ *,
-------
Methodology Used to Analyze Data Collected After the First Year
The requirements and objectives of sampling after the first year are
the same regardless of the test being applied. For the AR t-test only the
average concentration for each well (xm) is used in the calculation of
the t-test. A description of the sampling requirements and method for
calculating Xm are described in the prior section for the CABF test. No
variance is computed for the monitoring data collected after the first
year when using the AR test.
The AR t-statistic is calculated as follows:
x
t* = ra
Instead of calculating the critical t-statistic as described for the
CABF t-test, the critical t-statistic (t ) is obtained directly from
c
Table B-l. The t is the value from Table B-l which corresponds to
c
M - 1 degrees of freedom. The t* and t values are compared using
the same decision rules that are described above for the CABF t-test.
AN EXAMPLE OF APPLYING THE CABF AND AR T-TESTS TO A SET OF DETECTION
MONITORING DATA COLLECTED FROM AN INTERIM STATUS FACILITY
This section presents statistical analyses of data collected from a
properly designed and sampled interim status detection monitoring system.
Table B-2 presents an example of total organic halide (TOX) values
measured in parts per billion (ppb) collected from upgradient wells during
the first year of detection monitoring. This detection monitoring system
consists of four upgradient wells that were sampled bimonthly. Four
replicate samples were taken from each upgradient well at each sampling.
The array of wells, sampled bimonthly, allows spatial and temporal
evaluation of the upgradient ground-water quality. The statistics
describing the first years background data are presented in Table B-3 and
were computed using the CABF and AR methodology described above.
B-7
-------
TABLE B-2
AN EXAMPLE OF TOX DATA COLLECTED DURING THE FIRST YEAR FROM AN
UPGRADIENT WELL SYSTEM. THE OVERALL MEAN IS 65.2 ppb. THE
VALUE IN PARENTHESIS WAS MISSING AND WAS ESTIMATED USING THE
METHOD DESCRIBED FOR MISSING VALUES.
Well
Month Code Replicate
1 1 A
B
C
D
REPLICATE MEAN =
2 A
B
C
D
REPLICATE MEAN =
3 A
B
C
D
REPLICATE MEAN =
4 A
B
C
D
REPLICATE MEAN =
3 1 A
B
C
D
REPLICATE MEAN =
2 A
B
C
D
REPLICATE MEAN =
TOX
Value
(ppb)
67.4
67.2
68.0
67.1
67.43
66.6
67.1
65.9
66.3
66.48
68.0
67.5
67.6
67.6
67.68
60.1
59.1
58.7
62.1
60.0
65.2
63.0
62.7
64.0
63.73
60.9
61.7
62.8
62.2
61.9
B-8
Difference
Between the
Overall Mean
and the Value
- 2.2
- 2.0
- 2.8
- 1.9
- 2.23
- 1.40
- 1.90
- 0.70
- 0.10
- 1.28
- 2.80
- 2.30
- 2.40
- 2.40
- 2.48
5.10
6.10
6.50
3.10
5.20
0.0
2.20
2.50
1.20
1.47
4.30
3.50
2.40
3.00
3.30
Squared
Difference
4.84
4.00
7.84
3.61
4.97
1.96
3.61
0.49
1.21
1.64
7.84
5.29
5.76
5.76
6.15
26.01
37.21
42.25
9.61
27.04
0.0
4.84
6.25
1.44
2.16
18.49
12.25
5.76
9.00
10.89
-------
TABLE B-2 (Continued)
Well
Month Code Replicate
3 A
B
C
D
REPLICATE MEAN =
4 A
B
C
D
REPLICATE MEAN =
5 1 A
B
C
D
REPLICATE MEAN =
2 A
B
C
D
REPLICATE MEAN =
3 A
B
C
D
REPLICATE MEAN =
4 A
B
C
D
REPLICATE MEAN =
TOX
Value
(ppb)
63.2
63.0
62.7
62.9
62.95
57.8
58.2
58.0
58.7
58.18
65.0
65.2
66.8
66.3
65.83
60.9
61.3
62.0
61.7
61.48
63.0
63.2
62.7
61.9
62.7
56.3
57.8
57.9
58.1
57.53
(Continued)
Difference
Between the
Overall Mean
and the Value
2.00
2.20
2.50
2.30
2.25
7.40
7.00
7.20
6.50
7.02
0.20
0.0
- 1.60
- 1.10
- 0.63
4.30
3.90
3.20
3.50
3.72
2.20
2.00
2.50
3.50
2.50
8.90
7.40
7.30
7.10
7.67
Squared
Difference
4.00
4.84
6.25
5.29
5.06
54.76
49.00
51.84
42.25
49.28
0.04
0.0
1.56
1.21
0.40
18.49
15.21
10.24
12.54
13.84
4.84
4.00
6.25
10.89
6.25
79.21
54.76
53.29
50.41
58.83
B-9
-------
TABLE B-2 (Continued)
well
Month Code Replicate
"7 1
REPLICATE
2
REPLICATE
3
REPLICATE
4
REPLICATE
9 1
REPLICATE
2
REPLICATE
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
TOX
Value
(ppb)
63.2
63.2
63.8
63.8
63.5
64.0
63.6
63.8
64.0
63.85
65.6
67.9
70.2
68.1
67.95
64.8
64.0
65.2
(64.7)
64.68
65.7
65.9
64.2
66.0
65.45
63.8
64.2
64.7
64.0
64.18
Difference
Between the
Overall Mean
and the Value
2.00
2.00
1.40
1.40
1.70
1.20
1.60
1.40
1.20
1.35
- 0.40
- 2.70
- 5.00
- 2.90
- 2.75
0.40
1.20
0.0
0.5
1.52
- 0.50
- 0.70
1.00
0.80
- 0.25
1.40
1.00
0.50
1.20
1.20
Squared
Difference
4.00
4.00
1.96
1.96
2.89
1.44
2.56
1.96
1.44
1.82
0.16
7.29
25.00
8.41
7.56
0.16
1.44
0.0
0.25
0.27
0.25
0.49
0.64
0.64
0.06
1.96
1.00
0.25
1.44
1.04
(Continued)
B-10
-------
TABLE B-2 (Continued)
Well
Month Code Replicate
3
REPLICATE
4
REPLICATE
11 1
REPLICATE
2
REPLICATE
3
REPLICATE
4
REPLICATE
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
A
B
C
D
MEAN =
TOX
Value
(ppb)
65.0
65.1
65.9
66.3
65.58
61.8
61.4
61.3
51.1
61.4
69.7
72.0
71.5
70.6
70.95
73.4
75.2
76.0
75.4
75.0
71.1
74.0
72.3
73.7
72.78
72.7
74.9
73.0
73.6
73.55
Difference
Between the
Overall Mean
and the Value
0.20
0.10
- 0.70
- 1.10
- 0.38
3.40
3.80
3.90
4.10
3.80
- 4.50
- 6.80
- 6.30
- 5.40
- 5.75
- 8.20
-10.00
-10.80
-10.20
- 9.80
- 5.90
- 8.80
- 7.10
- 8.50
- 7.58
- 7.50
- 9.70
- 7.80
- 8.40
- 8.35
Squared
Difference
0.04
0.01
0.49
1.21
0.14
11.56
14.44
15.81
16.81
14.44
20.25
46.24
39.69
29.16
33.06
67.24
100.00
116.64
104.04
96.04
34.81
77.44
50.41
72.25
57.46
56.25
94.09
60.84
70.56
69.72
B-ll
-------
TABLE B-3
SUMMARY STATISTICS DESCRIBING THE FIRST YEAR'S BACKGROUND TOX DATA
PRESENTED IN TABLE B~2 USING THE COCHRAN'S APPROXIMATION TO THE
BEHRENS-FISHER AND THE AVERAGED REPLICATE t-TESTS
Cochran's Approximation of the
Behrens-Fisher t-Test
Average Replicate t-Test
Total number of replicate
measurements:
Nb = 96
Total number of replicate
averages:
Mb = 24
Degrees of freedom:
Nb - 1 = 95
Degrees of freedom:
Mb - 1 = 23
Background Mean:
nb °b Pb
I I I Xijk/Nb
=l j=l k=l J
Background Mean:
nb °b
X,. =
(67.4 + 67.2 + 68.0 +
67.1 + 66.6 + ... +
73.6)/96
= (67.43 + 66.48 + 67.68 +
+ 73.55)/24
Background Variance:
Background Variance:
= [(67.4 - 65. 2) +
(68.0 - 65. 2)2 + ..
(73.6 - 65.2)2]/95
= 20.38
= [(67.43 - 65.2) +
(66.48 - 65.2)2 +
(73.55 - 65.2)2]/23
= 20.48
B-12
-------
After the first year four replicate measurements are collected from
each upgradient and downgradient well. The measurements from each well
are evaluated individually by the t-test. In this example the TOX data
from a single semiannual sampling event are presented in Table B-4. Data
from the four background wells (1-4) which were sampled during the first
year and from the six downgradient wells (5-10) are compared using the
CABF and AR methods.
Table B-5 presents the statistics used in conducting the CABF t-test
and Table B-6 presents the statistics used in conducting the AR t-test.
It is apparent from the comparison of these tables that there is less
computational effort required to conduct the AR t-test. Also, notice in
Table B-5 that the CABF test indicated that well 5 had significantly
larger concentrations than the background data (because t* > t ), but
that the results of the AR test presented in Table B-6 indicated no
significant difference. The reason that the CABF test indicated a
significant difference is because the variance among the replicate samples
in well 5 as shown in Table B-4 was larger than any other well.
Table B-7 describes specifically, using data from well 6, how to
perform the calculations for the CABF and AR t-tests for data that are
collected after the first year.
B-13
-------
TABLE B-4
AN EXAMPLE OF TOX DATA, TAKEN DURING A SEMI-ANNUAL SAMPLING
EVENT, THAT WILL BE USED TO COMPARE WITH THE BACKGROUND TOX
DATA MEASURED DURING THE FIRST YEAR.
Location of
the Well
Upgradient
Downgradient
Well
Code Replicate
1 A
B
C
D
REPLICATE MEAN =
2 A
B
C
D
REPLICATE MEAN =
3 A
B
C
D
REPLICATE MEAN =
4 A
B
C
D
REPLICATE MEAN =
5 A
B
C
D
REPLICATE MEAN =
TOX
Value
(ppb)
64.8
64.2
65.0
64.7
64.68
65.7
65.3
65.6
65.1
65.43
64.8
65.2
64.9
65.0
65.43
65.3
65.3
65.3
65.2
65.28
68.4
69.7
68.6
67.7
68.6
Difference
Between the
Overall Mean
and the Value
- 0.12
0.48
- 0.32
- 0.02
- 0.27
0.13
0.17
0.33
0.18
0.22
0.08
0.02
- 0.02
- 0.02
- 0.02
0.08
0.20
- 1.10
0.0
0.90
Squared
Difference
0.0625
0.1225
0.2025
0.0225
2
s = 0.3476
0.0729
0.0169
0.0289
0.1089
2
S2 = 0.2276
0.0324
0.0484
0.0064
0.0004
2
S3 = 0.0876
0.0004
0.0004
0.0004
0.0064
2
s. = 0.0076
4
0.0400
1.2100
0.0
0.8100
s^ = 2.0600
(Continued)
B-14
-------
TABLE B-4 (Continued)
Location of Well
the Well Code Replicate
Downgradient 6 A
B
C
D
REPLICATE MEAN =
7 A
B
C
D
REPLICATE MEAN =
8 A
B
C
D
REPLICATE MEAN =
9 A
B
C
D
REPLICATE MEAN =
10 A
B
C
D
REPLICATE MEAN =
TOX
Value
(ppb)
66.3
66.2
65.7
66.8
66.25
64.7
65.3
65.0
65.1
65.03
64.2
64.5
64.3
64.3
64.33
66.7
63.4
65.2
65.7
65.25
62.8
63.4
63.3
63.2
63.18
Difference
Between the
Overall Mean
and the Value
- 0.05
0.05
0.55
- 0.55
0.33
0.27
0.03
0.07
0.13
- 0.17
0.03
0.03
1.45
1.85
0.05
- 0.45
0.38
- 0.22
- 0.12
- 0.02
Squared
Difference
0.0025
0.0025
0.3025
0.3025
2
s, = 0.6100
D
0.1089
0.0729
0.0009
0.0049
2
s? = 0.1876
0.0169
0.0289
0.0009
0.0009
2
s* = 0.0476
8
2.1025
3.4225
0.0025
0.2025
2
s. = 0.1876
9
0.1444
0.0484
0.0144
0.0004
2
SIQ = 0.2076
B-15
-------
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B-16
-------
TABLE B-6
A SUMMARY OF THE AVERAGED REPLICATE t-TEST APPLIED
TO THE TOX DATA PRESENTED IN TABLES B-2 AND B-4
Location of
the Well
Upgradient
Downgradient
Well
Code
1
2
3
4
5
6
7
8
9
10
xra ~ xb
- 0.65
0.23
- 0.22
0.08
3.40
1.05
- 0.17
- 0.87
0.05
- 2.02
t*
- 0.117
0.052
-0.050
0.018
0.767
0.237
- 0.038
- 0.196
0.011
0.456
tc (o = .01,23) = 2.500
- l/Mb = 4.526-^1-1/24 = 4.431
B-17
-------
TABLE B-7
A COMPARISON OF THE COCHRAN'S APPROXIMATION OF THE BEHRENS-FISHER AND
THE AVERAGED REPLICATE t-TEST METHODS APPLIED TO DATA COLLECTED AFTER
THE FIRST YEAR OF MONITORING FROM DOWNGRADIENT MONITORING WELL 6
Cochran's Approximation of the
Behrens-Fisher t-Test
Average Replicate t-Test
The mean (Xm) is:
The mean (Xm) is:
_
X = I X. /N
m _ km m
K "~ L
_ m
X = I X,/N
m ^ km m
= 66.3 + 66.2 + 65.7 + 66.8/4
= 66.25
= 66.3 + 66.2 + 65.7 + 66.8/4
= 66.25
The variance (s ) is:
m
m
- 2
(Xkm ' V /Nm
No variance is computed for the
monitoring data collected after
the first year when using the AR
t-test
= (66.3 - 66.25)2 + (66.2 - 66.25)2 +
(65.7 - 66.25)2 + (66.8 - 66.25)2/4-l
= 0.6100
The test statistic (t*) is:
The test statistic (t*) is:
t* =
Nm Nb
t* =
- 1/M
1.05
0.6040
= 1.738
1.05
= 0.237
4.526
(Continued)
B-18
- 1/24
-------
TABLE B-7 (Continued)
Cochran's Approximation of the
Behrens-Fisher t-Test
Average Replicate t-Test
The critical t value (tc) is:
W t + W.t.
mm b b
c W + Ww
m b
_ (.15525H4.541) + (2.123)(2.371)
.1525 + .2123
The critical t value (tc) is
obtained from the one-tailed
t-table (Table B-l) with Mb~l
degrees of freedom.
t =2.500
1.1959
0.3648
= 3.278
Decision of whether significantly
larger concentrations have been
measured in the monitoring well
under evaluation.
Decision of whether significantly
larger concentrations have been
measured in the monitoring well
under evaluation.
One-tailed:
One-tailed:
• If t* > tc then significantly
larger concentrations are
indicated.
If t* > tc then significantly
larger concentrations are
indicated.
t* = 1.738 < tc = 3.278 there-
fore no significant differences
were indicated.
• t* = 0.237 < tc = 2.500 there-
fore no significant differences
were indicated.
B-19
-------
APPENDIX C
DESCRIPTION OF SELECTED GEOPHYSICAL METHODS
AND ORGANIC VAPOR ANALYSIS
-------
APPENDIX C
SELECTED GEOPHYSICAL METHODS AND ORGANIC VAPOR ANALYSIS
This Appendix is a presentation of several investigative techniques
capable of augmenting data gathered from boreholes and ground-water
monitoring wells. The five methods are:
1. Ground Penetrating Radar (GPR)
2. Electromagnetic Conductivity (EM)
3. Resistivity
4. Seismic Refraction/Reflection
5. Organic Vapor/Soil Gas Analysis
The summaries of EM and resistivity focus on surficial and not
borehole methods. Although surficial and borehole techniques operate
under the same physical principles, the reader should be aware that
surficial and borehole techniques have different characteristics.
Surficial methods can be undertaken without regard to the number of
location or boreholes therefore providing a great deal of flexibility
to the investigation without disturbing the subsurface. Borehole EM and
resistivity, however, offer a much higher degree of resolution at depth
in the vicinity of a single borehole or between two or more.
The effectiveness of geophysical methods and organic vapor/soil
gas analysis increases if several techniques are used conjunctively.
For instance, EM, resistivity and organic vapor analysis are highly
correlative in the field where organic contamination exists.
C-l
-------
GROUND PENETRATING RADAR (GPR)*
Ground penetrating radar (GPR) uses high frequency radio waves to
acquire subsurface information. From a small antenna which is moved
slowly scross the surface of the ground, energy is radiated downward into
the subsurface, then reflected back to the receiving antenna, where
variations in the return signal are continuously recorded; this produces
a continuous cross-sectional "picture" or profile of shallow subsurface
conditions. These responses are caused by radar wave reflections from
interfaces of materials having different electrical properties. Such
reflections are often associated with natural geohydrologic conditions
such as bedding, cementation, moisture and clay content, voids, fractures,
and intrusions, as well as man-made objects. The radar method has been
used at numerous HWS to evaluate natural soil and rock conditions, as
well as to detect buried wastes.
Radar responds to changes in soil and rock conditions. An interface
between two soil or rock layers having sufficiently different electrical
properties will show up in the radar profile. Buried pipes and other
discrete objects will also be detected.
Depth of penetration is highly site-specific, being dependent upon
the properties of the site's soil and rock. The method is limited in
depth by attenuation, primarily due to the higher electrical conductivity
of subsurface materials. Generally, better overall penetration is
achieved in dry, sandy or rocky areas; poorer results are obtained in
moist, clayey or conductive soils. However, many times data can be
obtained from a considerable depth in saturated materials, if the
specific conductance of the pore fluid is sufficiently low. Radar
penetration from one to ten meters is common.
*GPR has been called by various names: ground piercing radar, ground
probing radar and subsurface impulse radar. It is also known as an
electromagnetic method (which in fact it is); however, since there are
many other methods which are also electromagnetic, the term GPR has come
into common use today, and will be used herein.
C-2
-------
The continuous nature of the radar method offers a number of
advantages over some of the other geophysical methods. The continuous
vertical profile produced by radar permits much more data to be gathered
along a traverse, thereby providing a substantial increase in detail.
The high speed of data acquisition permits many lines to be run across a
site, and in some cases, total site coverage is economically feasible.
Reconnaissance work or coverage of large areas can be accomplished using
a vehicle to tow the radar antenna at speeds up to 8 KPH. Very high
resolution work or work in areas where vehicles cannot travel can be
accomplished by towing the antenna by hand at much slower speeds.
Resolution ranges from centimeters to several meters depending upon the
antenna (frequency) used.
Initial in-field analysis of the data is permitted by the picture-
like quality of the radar results. Despite its simple graphic format,
there are many pitfalls in the use of radar, and experienced personnel
are required for its operation and for the interpretation of radar data.
Radar has effectively mapped soil layers, depth of bedrock, buried
stream channels, rock fractures, and cavities in natural settings.
Radar applications to HWS assessments include:
• Evaluation of the natural soil and geologic conditions.
• Location and delineation of buried waste materials, including
both bulk and drummed wastes.
• Location and delineation of contaminant plume areas.
• Location and mapping of buried utilities (both metallic and
non-metallic).
The radar system discussed in this document is a readily available
impulse radar system. Continuous wave (CW) or other impulse systems
exist, but they are generally one of a kind, being experimental instru-
ments, and are not discussed here.
C-3
-------
Figure C-l shows a simplified block diagram of a radar system.
The system consists of a control unit, antenna, graphic recorder, and
an optional magnetic tape recorder. In operation, the electronics are
typically mounted in a vehicle. The antenna is connected by a cable by
hand. System power is usually supplied by a small gasoline generator.
Various antennas may be used with the system to optimize the survey
results for individual site conditions and specific requirements.
C-4
-------
GRAPHIC RECORDER
ANTENNA
CONTROLLER
5-300 Meter
Cable
Radar
Waveform
O
O
TAPE RECORDER
GROUND SURFACE
SOIL
i I \
ROCK
FIGURE C-l
BLOCK DIAGRAM OF GROUND PENETRATING RADAR SYSTEM.
RADAR WAVES ARE REFLECTED FROM SOIL/ROCK INTERFACE.
C-5
-------
ELECTROMAGNETICS (EM)*
The electromagnetic (EM) method provides a means of measuring the
electrical conductivity of subsurface soil, rock and ground water.
Electrical conductivity is a function of the type of soil and rock, its
porosity, its permeability, and the fluids which fill the pore space. In
most cases, the conductivity (specific conductance) of the pore fluids
will dominate the measurement. Accordingly, the EM method is applicable
both to assessment of natural geohydrologic conditions and to mapping of
many types of contaminant plumes. Additionally, trench boundaries,
buried wastes and drums, as well as metallic utility lines can be located
with EM techniques.
Natural variations in subsurface conductivity may be caused by
changes in soil moisture content, ground water specific conductance,
depth of soil cover over rock, and thickness of soil and rock layers.
Changes in basic soil or rock types, and structural features such as
fractures or voids may also produce changes in conductivity. Localized
deposits of natural organics, clay, sand, gravel, or salt rich zones will
also affect subsurface conductivity.
Many contaminants will produce an increase in free ion concentration
when introduced into the soil or ground water systems. This increase
over background conductivity enables detection and mapping of contaminaed
soil and ground water at HWS, landfills, and impoundments. Large amounts
*The term electromagnetic has been used in contemporary literature as a
descriptive term for other geophysical methods, including GPR and metal
detectors which are based on electromagnetic principles. However, this
document will use electromagnetic (EM) to specifically imply the measure-
ment of subsurface conductivites by low-frequency electromagnetic induc-
tion. This is in keeping with the traditional use of the term in the
geophysical industry from which the EM methods originated. While the
authors recognize that there are many electromagnetic systems and manu-
facturers, the discussion in this section is based solely on instruments
which are calibrated to read in electrical conductivity units and which
have been effectively and extensively used at hazardous waste sites.
c-6
-------
of organic fluids such as diesel fuel can displace the normal soil
moisture, causing a decrease in conductivity which may also be mapped,
although this is not commonly done. The mapping of a plume will usually
define the local flow direction of contaminants. Contaminant migration
rates can be established by comparing measurements taken at different
t imes.
The absolute values of conductivity for geologic materials (and
contaminants) are not necessarily diagnostic in themselves, but the
variations in conductivity, laterally and with depth, are significant.
It is this variation which enables the investigator to rapidly find
anomalous conditions.
Since the EM method does not require ground contact, measurements
may be made quite rapidly. Lateral variations in conductivity can be
detected and mapped by a field technique called profiling. Profiling
measurements may be made to depths ranging from 0.75 to 60 meters.
Instrumentation and field procedures have been developed recently which
make it possible to obtain continuous EM profiling data to a depth of
15 meters. The data is recorded using strip chart and magnetic tape
recorders. This continuous measurement allows increased rates of data
acquisition and improved resolution for mapping small geohydrologic
features. Further, recorded data enhanced by computer processing has
proved invaluable in the evaluation of complex hazardous waste sites.
The excellent lateral resolution obtained from EM profiling data has been
used to advantage in efforts to outline closely-spaced burial pits, to
reveal the migration of contaminants into the surrounding soil, or to
delineate fracture patterns.
Vertical variations in conductivity can also be detected by the EM
method. A station measurement technique called sounding is employed for
this purpose. Data can be acquired from depths ranging from 0.75 to
60 meters. This range of depth is achieved by combining results from
C-7
-------
a variety of EM instruments, each requiring different field application
techniques. Other EM systems are capable of sounding to depths of
1,000 feet or more, but have not yet been used at HWS and are not
adaptable to continuous measurements.
Profiling is the most effective use of the EM method, continuous
profiling can be used in many applications to increase resolution, data
density, and permit total site coverage at critical sites.
At HWS applications of EM can provide:
• Assessment of natural geohydrologic conditions;
• Locating and mapping of burial trenches and pits containing drums
and/or bulk wastes;
• Locating and mapping of plume boundaries;
• Determination of flow direction in both unsaturated and saturated
zones;
• Rate of plume movement by comparing measurements taken at
different times; and
• Locating and mapping of utility pipes and cables which may affect
other geophysical measurements, or whose trench may provide a
permeable pathway for contaminant flow.
This document discusses only those instruments which are designed
and calibrated to read directly in units of conductivity.
The basic principle of operation of the electromagnetic method is
shown in Figure C-2. The transmitter coil radiates an electromagnetic
field which induces eddy currents in the earth below the instrument.
Each of these eddy current loops, in turn, generates a secondary electro-
magnetic field which is proportional to the magnitude of the current
flowing within that loop. A part of the secondary magnetic field from
each loop is intercepted by the receiver coil and produces an output
voltage which (within limits) is linearly related to subsurface
C-8
-------
Coil
SECONDARY FIELDS
FROM CURRENT LOOPS
SENSED BY
RECEIVER COIL
FIGURE C-2
BLOCK DIAGRAM SHOWING EM PRINCIPLE OF OPERATIONS
C-9
-------
conductivity. This reading is a bulk measurement of conductivity; the
cumulative response to subsurface conditions ranging all the way from the
surface to the effective depth of the instrument.
The sampling depth of EM equipment is related to the instrument's
coil spacing. Instruments with coil spacings of 1, 4, 10, 20, and
40 meters are commercially available. The nominal sampling depth of an
EM system is taken to be approximately 1.5 times the coil spacing.
Accordingly, the nominal depth of response for the coil spacings given
above is 1.5, 6, 15, 30, and 60 meters.
The conductivity value resulting from an EM insruraent is a
composite, and represents the combined effects of the thickness of soil
or rock layers, their depths, and the specific conductivities of the
materials. The instrument reading represents the combination of these
effects, extending from the surface to the arbitrary depth range of the
instrument. The resulting values are influenced more strongly by shallow
materials than by deeper layers, and this must be taken into
consideration when interpreting the data. Conductivity conditions from
the surface to the instrument's nominal depth range contribute about
75 percent of the instrument'~ response. However, contributions from
highly conductive materials lying at greater depths may have a
significant effect on the reading.
EM instruments are calibrated to read subsurface conductivity in
millimhos per meter (mm/m). These units are related to resistivity units
in the following manner:
1000/(millimhos/meter) = 1 ohm-meter
1000/(millimhos/meter) = 3.28 ohm-feet
1 millimho/meter = 1 siemen
The advantage of using millimhos/meter is that the common range of
resistivities from 1 to 1000 ohm-meters is covered by the range of
conductivities from 1000 to 1 millimhos/meter. This makes conversion of
units relatively easy.
C-10
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Most soil and rock minerals, when dry, have very low conductivities
(Figure C-3). On rare occasions, conductive minerals like magnetite,
graphite and pyrite occur in sufficient concentrations to greatly
increase natural subsurface conductivity. Most often, conductivity is
overwhelmingly influenced by water content and the following soil/rock
parameters:
• The porosity and permeability of the material;
• the extent to which the pore space is saturated;
• the concentration of dissolved electrolytes and colloids in the
pore fluids; and
• the temperature and phase state (i.e., liquid or ice) of the pore
water.
A unique conductivity value cannot be assigned to a particular material,
because the interrelationships of soil composition, structure and pore
fluids are highly variable in nature.
In areas surrounding HWS, contaminants may escape into the soil and
the ground-water system. In many cases, these fluids contribute large
amouns of electrolytes and colloids to both the unsaturated and saturated
zones. In either case, the ground conductivity may be greatly affected,
sometimes increasing by one to three orders of magnitude above background
values. However, if the natural variations in subsurface conductivity
are very low, contaminant plumes of only 10 to 20 percent above
background may be mapped.
In the case of spills involving heavy nonpolar, organic fluids such
as diesel oil, the normal soil moisture may be displaced, or a sizeable
pool of oil may develop at the water table. In these cases, subsurface
conductivites may decrease causing a negative EM anomaly. (A negative
anomaly will occur only if substantial quantities of nonconductive
contaminants are present.)
C-ll
-------
Conductivity (millimhos /meter)
ID'
Cloy and Marl
Loam
Top Soil
Clayey Soils
Sandy Soils
Loose Sands
River Sand and Gravel
Glacial Till
Chalk
Limestones
Sandstones
Basalt
Crystalline Rocks
I0
10'
10'
10
2
////////
V / / / 1
c
3
/ / / /I
/ / / // / / /
///////I
i
////////// y]
I/ /// /
I/ // /// /I
1
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f / /
///////////y
FIGURE C-3
RANGE OF ELECTRICAL CONDUCTIVTIBS IN NATURAL SOIL AND ROCK.
(Modified After Culley et al.)
C-12
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RESISTIVITY
The resistivity method is used to measure the electrical resistivity
of the geohydrologic section which includes the soil, rock, and ground
water. Accordingly, the method may be used to assess lateral changes and
vertical cross sections of the natural geohydrologic settings. In
addition, it can be used to evaluate contaminant plumes and locate buried
wastes at hazardous waste sites.
Application of the method requires that an electrical current be
injected into the ground by a pair of surface electrodes. The resulting
potential field (voltage) is measured at the surface between a second
pair of electrodes. The subsurface resistivity can be calculated by
knowing the electrode separation and geometry of the electrode positions,
applied current, and measured voltage. (Resistivity is the reciprocal of
conductivity, the parameter directly measured by the EM technique.)
In general, most soil and rock minerals are electrical insulators
(highly resistive); hence the flow of current is conducted primarily
through the moisture-filled pore spaces within the soil and rock.
Therefore, the resistivity of soils and rocks is predominantly controlled
by the porosity and permeability of the system, the amount of pore water,
and the concentration of dissolved solids in the pore water.
The resistivity technique may be used for "profiling" or "sounding."
Profiling provides a means of mapping lateral changes in subsurface
electrical properties. This field technique is well suited to the
delineation of contaminant plumes and the detection and location of
changes in natural geohydrologic conditions. Sounding provides a means
of determining the vertical changes in subsurface electrical properties.
Interpretation of sounding data provides the depth and thickness of
subsurface layers having different resistivities. Commonly up to four
layers may be resolved with this technique.
C-13
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Applications of the resistivity method at hazardous waste sites
include:
• Locating and mapping contaminant plumes;
• Establishing direction and rate of flow of contaminant plumes;
• Defining burial sites by
- locating trenches,
- defining trench boundaries,
- determining the depths of trenches; and
• Defining natural geohydrologic conditions such as
- depth to water table or to water-bearing horizons,
- depth to bedrock, thickness of soil, etc.
Most dry mineral components of soil and rock are highly resistive
except for a few metallic ore minerals. Under most circumstances, the
amount of soil/rock moisture dominates the mesurement greatly reducing
the resistivity value. Current flow is essentially electrolytic, being
conducted by water contained within pores and cracks. A few minerals
like clays actually contribute to conduction. In general, soils and
rocks become less resistive as:
• Moisture or water content increases;
• Porosity and permeability of the formation increases;
• Dissolved solid and colloid (electrolyte) content increases; and
• Temperature increases (a minor factor, except in areas of
permafrost).
Figure C-4 illustrates the range of resistivity found in commonly-
occurring soils and rocks. Very dry sand, gravel, or rock as encountered
in arid or semi-arid areas will have very high resistivity. As the empty
pore spaces fill with water, resistivity will drop. Conversely, the
resistivity of earth materials which occur below the water table but lack
pore space (such as massive granite and limestone) will be relatively
high and will be primarily controlled by current conduction along cracks
C-14
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Resistivity (ohm-meters)
's I04 I09
Cloy and Marl
Loam
Top Soil
Clayey Soils
Sandy Soils
Loose Sands
River Sand and Gravel
Glacial Till
Chalk
Limestones
Sandstones
Basalt
Crystalline Rocks
FIGURE C-4
RANGE OF RESISTIVITIES IN COMMONLY-OCCURRING SOILS AND ROCKS
(Modified after Culley et al.)
C-15
-------
and fissures in the formation. Clayey soils and shale layers generally
have low resistivity values, due to their inherent moisture and clay
mineral content. In all cases, an increase in the electrolyte, total
dissolved solids (TDS) or specific conductance of the system will cause a
marked increase in current conduction and a corresponding drop in
resistivity. This fact makes resistivity an excellent technique for the
detection and mapping of conductive contaminant plumes.
It is important to note that no geologic unit or plume has a unique
or characteristic resistivity value. Its measured resistivity is
dependent on the natural soil and rock present, the relative amount of
moisture, and its specific conductance. However, the natural resistivity
value of a particular formation or unit may remain within a small range
for a given area.
Figure C-5 is a schematic diagram showing the basic principles of
operation. The resistivity method is inherently limited to station
measurements, since electrodes must be in physical and electrical contact
with the ground. This requirement makes the resistivity method slower
than a noncontract method such as EM.
Many different types of electrode spacing arrays may be used to
make resistivity measurements; the more commonly used include wenner,
Schlumberger, and dipole-dipole. Due to its simple electrical geometry,
the Wenner array will be used as an example in the remainder of this
section; however, its use is not necessarily recommended for all site
conditions. The choice of array will depend upon project objectives and
site conditions and should be made by an experienced geophysicist.
Using the Wenner array, potential electrodes are centered on a line
between the current electrodes; and equal spacing between electrodes is
maintained. These "A" spacings used during HWS evaluation commonly range
from 0.3 meter to more than 100 meters. The depth of measurement is
related to the "A" spacing and may vary depending upon the geohydrology.
C-16
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Current Meter
Current Flow
Through Earth
Current
Voltage
Surface
Apparent resistivity values using the Wenner array are calculated
from the measured voltage and current and the spacing between electrodes
as shown in the following equation:
a = 2 A V/I
where a = apparent resistivity (ohm-meters or ohm-feet)
A = "A" spacing (meters or feet)
V = potential (volts)
I = current (arapers)
FIGURE C-5
DIAGRAM SHOWING BASIC CONCEPT OF RESISTIVITY MEASUREMENT
C-17
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Current is injected into the ground by the two outer electrtodes
which are connected by cables to a DC or low-frequency AC current source.
(If true DC is used, special nonpolarizing electrodes must be used.) The
distribution of current within the earth is influenced by the relative
resistivity of subsurface features. For example, homogenous subsurface
conditions will have the uniform current flow distribution and will yield
a resistivity value characteristic of the sampled section. On the other
hand, current distribution may be pulled downward by a low-resistivity
(lower than that of the surface layer, due to the influence of the lower
resistivity material at depth.
The current flow within the subsurface produces an electric field
with lines of equal potential, perpendicular to the lines of current
(Figure C-5). The potential field is measured by a voltmeter at the two
inner electrodes.
C-18
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SEISMIC REFRACTION
Seismic refraction techniques are used to determine the thickness
and depth of geologic layers and the travel time or velocity of seismic
waves within the layers. Seismic refraction methods are often used to
map depths to specific horizons such as bedrock, clay layers, and water
table. In addition to mapping natural features, other secondary
applications of the seismic method include the location and definition of
burial pits and trenches at HWS.
Seismic waves transmitted into the subsurface travel at different
velocites in various types of soil and rock and are refracted (or bent)
at the interfaces between layers. This refraction affects their path of
travel. An array of geophones on the surface measures the travel time of
the seismic waves from the source to the geophones at a number of
spacings. The time required for the wave to complete this path is
measured, permitting a determination to be made of the number of layers,
the thicknesses of the layers and their depths, as well as the seismic
velocity of each layer. The wave velocity in each layer is directly
related to its material properties such as density and hardness.
A seismic source, geophones, and a seismograph are required to make
the measurments. The seismic source may be a simple sledge hammer with
which to strike the ground. Explosives and any other seismic sources may
be utilized for deeper or special applications. Geophones implanted in
the surface of the ground translate the received vibrations of seismic
energy into an electrical signal. This signal is displayed on the
seismograph, permitting measurement of the arrival time of the seismic
wave, since the seismic method measures small ground vibrations, it is
inherently susceptible to vibration noise from a variety of natural and
cultural sources.
At HWS, seismic refraction can be used to define natural geohydro-
logic conditions, including thickness and depth of soil and rock layers,
C-19
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their composition and physical properties, and depth to bedrock or water
table. It can also be used for the detection and location of anomalous
features, such as pits and trenches, and for evaluation of the depth of
burial sites or landfills. (In contrast to seismic refraction, the
reflection technique, which is common in petroleum exploration, has not
been applied to HWS. This is primarily because the method cannot be
effectively utilized at depths of less than 20 meters.)
Although a number of elastic waves are inherently associated with
the method, conventional seismic refraction methods that have been
employed at HWS are concerned only with the compressional wave (primary
or P-wave). The compressional wave is also the first to arrive which
makes its identification relatively easy.
These waves move through subsurface layers. The density of a layer
and its elastic properties determine the speed or velocity at which the
seismic wave will travel through the layer. The porosity, mineral
composition, and water content of the layer affect both its density and
elasticity. Table C-l lists a range of compressional wave velocities in
common geologic materials. It can be seen from these tables that the
seismic velocities for different types of soil and rock overlap, so
knowing the velocities of these layers alone does not permit a unique
determination of their composition. However, if this knowledge is
combined with geologic information, it can be used intelligently to
identify geologic strata.
In general, velocity values are greater for:
• dense rocks than light rocks.
• older rocks than younger rocks.
• igneous rocks than sedimentary rocks.
• solid rocks than rocks with cracks or fractures.
C-20
-------
TABLE C-l
RANGE OF VELOCITIES FOR COMPRESSIONAL WAVES IN SOIL AND ROCK
(After Jakosky, 1950)
Material
Weathered surface material
Gravel or dry sand
Sand (wet)
Sandstone
Shale
Chalk
Limestone
Salt
Granite
Metamorphic rocks
Velocity
305
465
610
1,830
2,750
1.830
2,140
4,270
4,380
3,050
(Meters/sec)
610
915
- 1,830
- 3,970
- 4,270
- 3,970
- 6,100
- 5,190
- 5,800
- 7,020
C-21
-------
• unweathered rocks than weathered rocks.
• consolidated sediments than unconsolidated sediments.
• water-saturated unconsolidated sediments than dry unconsolidated
sediments.
• wet soils than dry soils.
Figure C-6 shows a schematic view of a 12-channel seismic system in
use and the compessional waves traveling through a two-layered system of
soil over bedrock. A seismic source produces seismic waves which travel
in all directions into the ground. The seismic refraction method,
however, is concerned only with the waves shown in Figure C-6. One of
these waves, the direct wave, travels parallel to the surface of the
ground. A seismic sensor (geophone) detects the direct wave as it moves
along the surface layer. The time of travel along this path is related
to the distance between the sensor and the source and the material
composi;., the layer.
If a denser layer with a higher velocity, such as bedrock, exists
below the surface soils, some of the seismic waves will be bent or
refracted as they enter the bedrock. This phenomenon is similar to the
refraction of light rays when light passes from air into water and is
described by Snell's law. One of these refracted waves, crossing the
interface at a critical angle, will move parallel to the top of the
bedrock at the higher velocity of the bedrock. The seismic wave
travelling along this interface will continually release energy back into
the upper layer by refraction. These waves may then be detected in the
surface at various distances from the source (Figure C-6).
Beyond a certain distance (called the critical distance), the
refracted wave will arrive at a geophone before the direct wave. This
happens even though the refraction path is longer, because a sufficient
portion of the wave's path occurs in the higher velocity bedrock.
C-22
-------
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C-23
-------
Measurement of these first arrival times and their distances from the
source permits calculation of layer velocities, thicknesses and bedrock
depth. Application of the seismic method is generally limited to
resolving three to four layers.
The preceding concepts are based upon the fundamental assumptions
that:
1. Seismic velocities of geologic layers must increase with depth.
This requirement is generally met at most sites.
2. Layers must be of sufficient thickness to permit detection.
3. Sesimic velocities of layers must be sufficiently different to
permit resolution of individual layers.
There is no way to establish from the seismic data alone whether a hidden
layer (due to 1 and 2 above) is present; therefore, correlation to a
boring log or geologic knowledge of the site must be used to provide a
cross check. If such data is not available, the interpreter must take
this into consideration in evaluating the data.
Variations in the thickness of the shallow soil zone, inhomo-
geneities within a layer, or irregularities between layers will often
produce geologic scatter or anomalies in the data. This data scatter
is useful information, revealing some of the natural variability of the
site. For example, a zone containing a number of large boulders in a
glacial till deposit will yield inconsistent arrival times, due to
variable seismic velocities between the boulders and the clay matrix.
An extremely irregular bedrock surface as is often encountered in karst
limestone terrain, likewise, will produce scatter in the seismic data.
The seismic refraction technique uses the equipment shown in
Figure C-6. The seismic source is often a simple ten-pound sledge hammer
or drop weight which strikes the ground, generating a seismic impulse.
Explosives and a variety of other excitation sources are also used for
the greater energy levels rquired for information at deeper layers.
C-24
-------
Seismic waves are detected by geophones implanted in the surface of
the ground at various distances from the source. The geophone converts
the seismic wave's mechanical vibration into an electrical signal in a
manner similar to that of a microphone. This signal is carried by cable
to the seismograph.
The seismograph is an instrument which electronically amplifies and
then displays the received seismic signal from the geophone. The display
may be a cathode ray tube, a single-channel strip chart, or a thermal
printer, commonly used on multi-channel systems. The identification and
measurement of the arrival time of the first wave from the seismic source
is obtained from this presentation. The time is measured in milliseconds,
with zero time or start of trace intitiated by the source, which provides
a trigger signal to the seismograph.
Travel time is plotted against source-to-geophone distance producing
a time/distance (T/D) plot.
• The number of line segments indicates the number of layers.
• The slope of each line segment is inversely proportional to the
seismic velocity in the corresponding layer.
• Break points in the plot (critical distance, X) are used with the
velocities to calculate layer depth.
The seismic line must be centered over the required information area
and overall line length must be three to five times the maximum depth of
interest. Resolution is determined by the geophone spacing. Spacings of
3 to 15 meters are commonly used; however, closer spacings may be
necessary for very high resolution of shallow geologic sections.
C-25
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ORGANIC VAPOR/SOIL GAS ANALYSIS
Organic contaminant vapors present in the vadose zone may be
assessed using a variety of techniques. One method is the use of organic
vapor detectors such as OVAs, explosimeters and Draeger tubes to detect
volatile organics. Two major strategies may be adopted, jointly or
separately, depending on whether wells are in place at the time of
investigation:
1. Monitoring the well head space.
2. Monitoring the vadose zone directly by lowering a probe into
shallow, hand-augurred holes.
Gaseous sample constituents can be identified in detail using a
portable gas chromatograph. An alternative methodology is an analysis of
soil gas. Under this methodology, a ten-liter sample of soil gas is
drawn through a probe which is mechanically driven into the ground to a
depth of about ten feet. Two cubic centimeters of gas are injected into
a portable gas chromatograph to ascertain its organic constituents. It
is useful to know what class of organics is present in order to choose
the gas chromatography method which provides the highest resolution,
i.e., photoionization/aromatics, electron-capture/halogenated hydro-
carbons. The 2 cc sample is injected by syringe to the gas chromatograph
through a dewatering napthalon tubing. This method is limited in two
major ways:
1. Coarse, pebbly/cobbly strata prevent penetration of the probe,
in which case holes may be hand-augured.
2. The presence of shallow, saturated zones, especially low
permeability formations severely restricts the development of a
gas envelope and thus limits the applicability of the method.
Soil gas analysis is a vadose zone monitoring technique and
cannot be used effectively where the water table or saturation
is shallow.
Organic vapor/soil gas analysis is most effective when used in
conjunction with other investigative methods. Although it provides an
C-26
-------
analysis of the volatile organics and thus provides a preliminary
characterization of the subsurface contamination, it is limited to a
fraction of the total hazardous constituents and needs augmentation.
C-27
-------
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-------
CHAPTER 3
GROUND WATER
DRAFT
I. INTRODUCTION
The essential objective of the PA/SI in relation to ground
water is to determine for each solid waste management unit at the
RCRA facility whether or not the unit has released or is likely to
have released hazardous wastes or constitutents to the uppermost
aquifer. For units which have identified releases/ or for which
there is a substantial likelihood of a release, further investigations
will be required of the owner/operator to actually determine the
extent of a release(s) and/or to characterize the release and begin
the development of a program of corrective measures.
The determination as to the need for further ground water
investigations at a unit must be made on a case-by-case basis,
considering the various relevant factors which are unique to each
unit. For some units the potential for ground water contamination
will not be difficult to assess, and the determination of need for
further investigations will be relatively straightforward. For
other units, however, the potential for contamination will be less
than obvious, and the determination will necessarily be based on
judgement of the individuals conducting and reviewing the results
of the PA/SI, combined in some cases with actual sampling and
analysis.
In making determinations from the PA/SI as to the need for
additional ground water investigations, it must be recognized that
comprehensive ground water investigations will typically require a
considerable investment of time and resources for both the owner/
operator in conducting the actual investigations, and for the
reviewing agency in reviewing technical plans, hydrogeologic data
and analytical results. This economic and resource concern must be
balanced against the essential mandate of protecting human health
and the environment; i.e.., the need to identify ground water
contamination and begin the process of cleaning up that contamination.
It is therefore the dual function of the PA/SI to conservatively
identify situations which merit additonal ground water investigations,
and at the same time to avoid requiring unnecessary investigations.
II. UNITS OF CONCERN
Each solid waste managment unit at the facility should be
evaluated for its potential to be causing or to have caused ground
water contamination. The exception to this is for "regulated
units"; i.e., landfills, surface impoundments, waste piles and land
treatment units which received wastes after July 26, 1983. Releases
to ground water from regulated units must be addressed in permits
according to the requirements of Subpart F of Part 264 (or cor-
-------
responding State regulations), rather than through the §3004(u)
authority. Thus, investigation of ground water contamination from
regulated units will not be"part of the PA/SI.
III. EXISTING GROUND WATER MONITORING SYSTEMS
An assessment should be made in the preliminary assessment and
the site investigation of any existing ground water monitoring
systems at the facility which may be capable of detecting releases
from solid waste management units (swmus) at the facility. Some
swmus may have a monitoring system installed specifically for the
unit. In other cases a monitoring system placed at a regulated
unit(s) or other units may also be capable of monitoring the swmu.
An example of this might be a closed landfill cell surrounded by
several active cells.
If it is determined from the preliminary assessment that an
existing system is installed at a swmu, that system should be
carefully examined for its technical adequacy [i.e., to what extent
does it meet the general performance standard in §264.97(a)].
Information required to assess the adequacy of an existing monitoring
would include: detailed information on geology and hydrogeology at
the unit, waste characteristics, background and downgradient water
quality data, boring logs, well design information, and sampling and
analytical procedures.
In evaluating whether a monitoring system which was installed
at another unit(s) (such as a regulated unit) may be capable of
also detecting releases from a swmu, particular attention must be
paid to such features as proximity of the swmu to the regulated
unit, the direction of ground water flow, well locations in relation
to the swmu, and whether or not the appropriate constituents are
being monitored for the wastes in the swmu. Figure 3-1 provides a
graphic illustration of three different situations in which existing
monitoring systems at regulated units may or may not also adequately
monitor a swmu.
I fan existing ground water monitoring system and program of
sampling and analysis is determined to be adequate to detect releases
to ground water from the solid waste management unit, and recent
analytical data (e.g., within the past three months) indicate that
there have been no releases, no further investigations should be
required of the owner/operator. If the existing system is not
adequate, and the investigator determines that there is a likelihood
of ground water releases from the unit (see below), the owner/operator
should be required to conduct additional investigations as necessary,
and install additional monitoring wells and/or analyze for more or
different constituents, as part of the remedial investigation phase.
Phase II of the technical guidance will address design of appropriate
monitoring systems and analytical programs for solid waste management
units.
There may be situations where existing monitoring systems are
adequate to detect contamination from the unit and no contamination
-2-
-------
FIGURE 3-1
MONITORING WELL LOCATION
Case One
\U
V O WMA
° (* ~^\
1 RU RU T
SWMU • T
1 r I
1 RU RU 9
1 t
v X
No new wells may be
neaded for SWMU if all
units are closely spaced.
Case Three
/ WMA
\ f~\ 1 1 — — — ^^
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Case Two
O
/
1
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to
rem
\
-> \ GW .
SWMU ' il O
| * WMA
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Is for RUs ' ' ' j
adequate 1 f A
SWMU due | RU ^
geographic [ *
o teness . '
1 RU
--•
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SWMU -
RU -
WMA -
O-
• -
->vGW
^s^-^ m
solid waste manage-
ment unit
regulated unit
waste management
area
background monitoring
well
downgradient moni-
tor ing well
ground-water flow
d i rec tion
New wells needed for SWMU due
to presence of a ground-wter
d Ivide.
Note: Drawings not to scale
-3-
-------
has yet been evidenced, but based on the type of unit, its design,
the wastes managed or other factors, there is a likelihood of a
ground water release in the future. In such situations, the owner/
operator should be required (as a permit condition, if -the facility
is permitted) to maintain the system and carry out an appropriate
sampling/analysis program.
IV. UNIT ASSESSMENT FOR GROUND WATER
Each swmu at the facility which is not adequately monitored by
an existing ground water monitoring system, and which contains or
has contained wastes capable of releasing hazardous constituents to
ground water, must be assessed to determine the likelihood of
ground water releases, and thus the need for further ground water
investigations. This unit assessment will be based on the information
gathered in the preliminary assessment, inspection of the unit
during the site inspection, and other information generated as
necessary. The unit assessment should be made based on the following:
o An understanding of the overall potential of the unit to
cause ground water releases;
o An understanding of the primary mechanisms by which releases
may occur from the unit;
o An assessment of unit-specific factors which, singly or in
combination, indicate the relative likelihood of ground water
releases from the unit; and
o Exposure potential.
A discussion of each of these elements of the unit assessment
follows.
V. POTENTIAL FOR AND MECHANISMS OF GROUND WATER RELEASES
The general potential for ground water contamination from a
swmu is, to a great extent, dependent upon the nature and function
of the unit. This is reflected in RCRA hazardous waste regulations.
For example, ground water monitoring is not a requirement for
container storage units, while with few exceptions monitoring is
required for landfills. It is thus necessary, in making an assessment
of the likelihood of ground water releases from a unit, to first
consider the relative potential of the unit to release. Table 3-1
presents a generalized ranking, in rough descending order, of the
different types of swmus and their overall potential for causing
ground water contamination, and a listing of the most common mechanisms
by which ground water releases can occur from each unit type.
Section VIII of this chapter also provides for each type of unit
examples of units which would and which would not merit further
ground water investigations.
-4-
-------
TABLE 3-1. UNIT POTENTIAL FOR GROUND WATER
RELEASES AND MECHANISMS OF RELEASE
Unit Type
Class IV Injection
Well
Surface Impoundment
Landfill
Land Treatment Unit
Class I Injection
Well
Underground Tank
Waste Pile
In-ground Tanks
Release Mechanism
o Wastes are injected directly into the sub-
surface
o Escape of wastes from well casing
o Spillage or other releases from waste handling
operations at the well head
o Migration of wastes/constituents through liners
(if present) and soils
o Damage to liners
o Overflow events and other spillage outside the
impoundment
o Seepage through dikes to surface and/or sub-
surface
o Migration of leachate through liners (if present)
and soils
o Precipitation runoff to surrounding surface
and subsurface
o Spills and other releases outside the containment
area from loading/unloading operations
o Migration of constituents through the unsatur-
ated zone
o Precipitation runoff to surrounding surface
and subsurface
o Migration of wastes from the injection zone
through confining geologic strata to upper
aquifers
o Escape of wastes from well casings
o Spillage or other releases from waste handling
operations at the well head
o Tank shell failure
o Leaks from piping and ancillary equipment
o Spillage from coupling/uncoupling operations
o Overflow
o Leachate migration through liner (if present)
and soils
o Precipitation runoff to surface/subsurface
o Overflow
o Tank wall failure
o Leaks from ancillary equipment
o Spillage from coupling/uncoupling operations
-5-
-------
Container Storage
Unit
Above Ground Tank
Incinerator
o Spills from containers/container failure and
subsequent migration through liners (if any)
and soils
o Precipitation runoff from stora'ge areas
o Overflow
o Shel1 failure
o Leaks from ancillary equipment
o Coupling/uncoupling operations
o Spillage or other releases fro waste handling/
preparation activities
o Spills due to mechanical failure
-6-
-------
It should be understood that Table 3-1 is intended only to
provide a very theoretical sense of the relative potential of units
to cause ground water releases. Unit-specific factors (as described
below) must be evaluated in determining whether further, ground
water investigations are needed for a particular unit.
VI. EVALUATION OF UNIT-SPECIFIC FACTORS
The following unit-specific factors should be evaluated in
assessing a swmu for ground water releases:
A. Unit design
B. Site geology/hydrogeology
C. Waste characteristics
D. Operational history
E. Physical integrity of the unit
F. Evidence of contamination
In making a unit assessment attention should be paid to how
two or more of the above factors may combine to suggest whether or
not releases are have occurred. For example, examination of an
above ground tank may reveal evidence of soil contamination ("F"
above) adjacent to the unit. However, the operational history of
the unit ("D") reveals that the tank has been in operation for only
six months, the tank is in good condition ("E"), and records indicate
that the contamination occurred as a single, relatively small
overflow event. In addition, the waste ("C") is known to be relatively
non-mobile, and clay soils underlie the facility, with an uppermost
aquifer that is quite deep ("B"). In this situation, the likelihood
of a release to ground water is very remote, and further investigations
would not be indicated.
The factors listed above are discussed in more detail, as
follows:
A. Unit Design. Focus of evaluation:
o Does the unit have engineered features designed to
prevent releases to ground water?
o Are such features adequate?
o Capacity and dimensions
Examples of design features of concern for specific types
of units are given in Section VIII of this chapter.
B. Site Geology/Hydrogeology. Focus of evaluation:
o What is the potential for releases of any wastes or
constituents from the unit to contaminate ground water,
based on soil characteristics, geologic formations,
climate, aquifer location, subsurface drainage patterns,
seasonal variations and other factors?
-7-
-------
This evaluation should rely on standard geologic and hydrogeologic
principles, using whatever information is available on the subsurface
characteristics of the site. If information on subsurface character-
istics indicates that the potential for contamination of ground
water is very low (e.g., facility overlying thick formation of low
permeability clay, in an arid area with a very deep aquifer),
further ground water investigations would be needed only for units
for which other factors indicate a very high potential for causing
contamination (e.g., a Class IV injection well). Likewise, if
ground water is particularly vulnerable (e.g., facility overlies
sandy soils and a shallow aquifer in a high recharge area), a
correspondingly low threshold would be applied in determining the
need for additonal ground water investigations.
Where very little is known of a facility's subsurface
characteristics, other unit-specific factors will need to be weighed
more heavily in making the ground water assessment. In many cases,
evaluation of unit design and waste characteristics alone may be
sufficient to determine that ground water investigations are
necessary, even though very little may be known about subsurface
characteristics. An example of this could be a large, unlined
surface impoundment.
C. Waste Characteristics. Focus of evaluation:
o What is the potential for wastes managed in the unit
to migrate to the uppermost aquifer, based on their
concentration, physical/chemical properties, and
behavior in water and soils?
There is considerable variation in the relative likelihood
of different hazardous constituents to actually migrate from a
given unit through the unsaturated zone and into and through ground
water. Many of the constituents in Appendix VIII are essentially
insoluble in water (at neutral pH) and/or bind tightly to soil
particles, reducing the likelihood of contamination of ground water.
The investigator should consider the potential mobility of the
waste(s) in a unit, in combination with other unit-specific factors.
The relative mobility of waste constituents can be expressed by
the sorption equilibrium constant (K^). The K
-------
where a number of wastes are present in a unit (e.g., in a commercial
landfill), the values given in Appendix 3-1 will have little
application.
•
D. Operational History of the Unit. Focus of evaluation:
o To what extent, and how, does the operational history
of the unit indicate that a release to ground.water from
the unit may have occurred?
Operational factors which may influence the likelihood of
ground water releases may include:
—Service life of the unit. Units which have been managing
wastes for long periods of time will usually have a greater
likelihood of releases than units which have been operating
for short periods of time. For example, an underground tank
which has been in service for six months will have a much
smaller likelihood of leakage due to corrosion than will a
twenty-year old underground tank.
—Operational status. In some cases, the operational status
of a storage unit (e.g., closed, inactive, decomissioned) may
have an effect on the relative likelihood of a ground water
release.
—Operating procedures. Proper maintenance, regular inspections,
and procedures for ensuring waste compatibility with the unit
may provide indication that a unit is unlikely to have released
(this is particularly true for storage units such as tanks
and container storage areas). Evidence of good operational
practices may be available from owner/operator records,
and/or visual observation or historical inspection reports.
Conversely, poor operating practices (e.g., underground
tanks which are never leak tested or inspected internally,
storage of open containers of wastes) may indicate relatively
greater potential for ground water releases.
E.'~- Physical Condition of Unit. Focus of evaluation:
o Does the physical condition of the unit indicate a likeli-
hood of releases that may contaminate ground water?
Examples of how physical condition of certain types of units
may indicate potential for releases are given in Section VIII of
this chapter.
F. Evidence of Release. Focus of evaluation:
o Is there evidence, either visual or from existing sampling
data of soils and/or ground water, which indicates that
a release to ground water has or is likely to have
occurred?
o Is additional sampling data necessary to determine the
-------
need for further ground water investigations at the unit?
If so, how should such sampling/analysis be conducted?
In some cases, visual examination of a unit or the area
surrounding the unit may reveal substantial soil contamination
(e.g., discolored soil, lack of or distressed vegetation), as an
indication of possible contamination. An organic sheen on nearby
surface water may similarly provide indication of contamination-
At some facilities, ground water sampling data from existing
monitoring wells at the facility, or from wells or springs near the
facility may be available and may indicate the presence of hazardous
constituents which could have migrated from a unit(s) at the facility,
Such data may not be conclusive evidence of a release from any
unit, due to the variabilities inherent in ground water flow,
background ground water quality, errors or deficiencies in sampling
and analysis, and other factors. However, if existing ground water
data does exist from nearby wells or springs, and suggests contam-
ination, even though wells may not have been placed for the purpose
of monitoring the unit(s) and relatively little may be known of
subsurface characteristics, such data should be considered a very
strong indication of the need for further, more intensive ground
water investigations for the facility.
If, from an evaluation of all of the above factors—unit
design, site geology/hydrogeology, waste characteristics, operational
history, physical condition, and existing evidence of contamination—
it is not possible to make a reasonably assured determination as to
whether a ground water release from the unit has or is likely to
have occurred, the investigation should consider whether additional
sampling and analysis of soils and/or ground water, should be done
to enable the determination to be made. The following are examples
of situations where additional sampling might be indicated;
o Evaluation of unit-specific factors indicates that a release
has probably not occurred, but there is need for an extra
measure of certainty before a determination can be made that
no ground water investigations are necessary.
o The evaluation indicates a likelihood of releases to ground
water from the unit, but more definitive evidence is necessary
to establish the need for extensive remedial investigations
(or immediate corrective measures).
An illustration of a situation in which sampling would be called
for is as follows: An outdoor, unsurfaced area at a facility was
used as a container storage area for a number of years, but has
not been used since 1980. The facility is located in an area with
sandy soils. Inspection of the area reveals vegetation growing on
the area, with no visible signs of contamination. However, a
review of the operating history of the facility indicates that
the volume of wastes stored in this location was very large, and a
number of enforcement actions for serious interim status violations
have been initiated against the facility, and State inspection
records from the late 1970's indicate generally poor housekeeping
-10-
-------
practices. Because of these uncertainties, soil sampling of the
area would be recommended.
«
In some cases, sampling and,analysis of soils may yield
sufficient evidence to enable the investigator to determine•the
likelihood of a release to ground water. In other situations,
sampling of ground water from existing nearby wells or springs
would be advisable if there is reason to believe that constituents
from the unit could migrate to such wells or springs.
For any sampling of soils or ground water conducted as part of
the site investigation, the constituents to be analyzed should be
those which would be expected to migrate from the unit, based on
what is known of the wastes managed in the unit. When little is
known of the wastes managed in the unit, the investigator will have
to exercise judgement as to the appropriate parameters and constit-
uents to be analyzed.
Appendix 3-2 provides three different lists which may be used
in determining which parameters and constituents should be analyzed
for in ground water. Each of the lists has been developed using
data from monitoring data at CERCLA sites, and as such reflects the
experience of the Agency as to the types of compounds which are
most typically found in contaminated ground water at various types
of sites. List A in Appendix 3-2 is a list of basic parameters
which may be useful in providing a general indication of the exis-
tence of contamination. The list is analogous to, but an expansion
of, the four basic monitoring parameters required under interim
status. List B provides three more specific listings of constituents
which have typically been detected at specific industries-metal
finishing, iron and steel manufacturing, and pesticides manufacturing.
These industry-specific lists may be used in combination with List
A if the facility is engaged in one of these three industries.
Additional lists for specific industries are being developed. List
C is a more complete listing of the most commonly detected constit-
uents from CERCLA sites. This list may be used, if necessary, as a
supplement to List A, in situations where little is known of the
wastes in the unit, and the facility is not engaged in any of the
three industries listed above.
Actual installation of new ground water monitoring wells as
necessary will typically take place during trhe remedial investigation
phase, and will not normally be done as part of the site investigation.
The determination as to the need for additional ground water invest-
igations at a unit should be able to be made without having to
install new wells. However, installation of new monitoring wells
and ground water sampling and analysis is not precluded as a part
of a site investigation. An example of a situation in which instal-
lation of new wells might be done is as follows:
o Evaluation of unit-specific factors reveals that a release
has probably not occurred, but an extra degree of certainty
is desirable, due to the presence of down gradient drinking
water wells (see Section VII on exposure potential); and
-11-
-------
o A sufficient amount of information is available on site
hydrogeology to enable reasonably well designed and located
wells to be installed without substantial preliminary sub-
surface investigations'; and
o The wells can be installed, sampled and analyses obtained
within a relatively short period of time.
VII. EXPOSURE POTENTIAL
The potential for exposure of human populations to hazardous
constituents in ground water which may be occurring or could
potentially occur from releases to ground water from the facility
should be considered by the investigator in making determinations
of the need for further ground water investigations. If the
potential for exposure to ground water contamination from a facility
is high, a greater degree of certainty will be necessary in making
determinations that further investigations are not needed at the
facility. Likewise, if potential for exposure is low, fewer or
less extensive investigations may be required of the owner/operator.
To illustrate, information available to the investigator may reveal
that drinking water wells are located within a relatively short
distance from the facility (e.g., 1/4 mile), and that these wells
are located down gradient from the facility and ground water flow
is relatively rapid. In this situation, the potential for exposure
to the drinking water well users is relatively high, and a substantial
degree of certainty would therefore be needed in determining that
ground water releases are unlikely at the facility. Thus, for an
underground tank at the facility which stores highly mobile and
toxic wastes but which would otherwise be judged unlikely to be
causing contamination (based on design, age, etc.), it may be
prudent to require in the remedial investigation phase installation
of some type of monitoring system for the tank. Conversely,
there may be some situations in which the potential for human
exposure to ground water contamination from a unit would be
extremely low, and would thus suggest that ground water investi-
gations-for a unit might be unnecessary.
viii. ILLUSTRATIONS'
As a means of illustrating and summarizing the foregoing
discussion, Table 3-2 is intended to provide specific examples of
the kinds of units which would and which would not merit remedial
ground water investigations, based on the general potential for
contamination, unit specific factors, and exposure potential.
This table is not intended to be a complete listing of the types
of units and situations which are expected to be encountered at
RCRA-regulated facilities. It is rather meant to give a sense of
the types of unit scenarios in which remedial investigations
generally would and would not be needed.
-12-
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TABLE 3-2. UNIT ILLUSTRATIONS
Unit Type
Further Investigation
Needed
Further Investigation
Not Needed
Class IV
Injection Wells
Surface
Impoundments
Landfills
o All Class IV wells
o Unlined/ active impoundments
o Impoundments which closed with
wastes in-place
o Inactive or active clay-lined
impoundments which held wastes
for more than a very short
period of time (e.g., >1 month)
o Small, synthetic lined impound-
ments with evidence or records
of liner deterioration and/or
rupture
o Unlined impoundments which closed
by removal of wastes, but at
which no ground water monitoring
system, or an inadequate system,
is installed
o Closed/inactive commercial land-
fill units
o Landfill units containing sub-
stantial quantities of municipal-
type solid waste
o Unlined monofills of wastes with
relatively non-mobile constituents,
in areas with high water tables
o Closed, clay-lined landfill units
containing relatively mobile
and/or toxic containerized or
non-containerized wastes
o Areas.of facilities with heavily
contaminated soils resulting from
routine, systematic and deliberate
placement of wastes on the soil
(e.g., wood preservative "kick-back"
areas
-13-
o None
o Units which closed by removal of
wastes ("clean closed") in
accordance with §265.228(b) or
§264.228(a)(l) (see footnote #1)
o Small, clay or synthetic lined
impoundments which held relatively
non-mobile wastes (e.g., certain
fly ashes) for a short period of
time
o Impoundments which were synthetic-
ally or concrete lined, whose
liners have been removed, and where
adequate soil sampling and physical
evidence conclusively demonstrates
that no leakage occurred from the
unit
o Small rubbish dumps
o Monofills of wastes having very low
potential for migration of con-
stituents to ground water (e.g.,
insoluble metal salts, certain fly
ashes), and which have been
adequately capped or covered by
structures, in locations where the
uppermost aquifer would never come
in direct contact with the wastes
o Small units containing wastes with
relatively non-mobile constituents
in arid areas with deep aquifers,
which are constructed with well-
designed liners and leachate col-
lection systems and/or which are
situated over relatively imperm-
eable natural geologic formations
(e.g., clay deposits)
-------
^Ri
Treatment
ts
Class I
Injection Wells
Underground Tanks
Waste Piles
o Active or inactive land treatment
units in non-arid areas on which
substantial amounts of wastes
have been placed
o See footnote #2
o Units on which wastes were placed
only once, in very small amounts,
in an area wi'th a deep water table
o A very small (e.g., 0.1. hectare)
experimental land treatment plot
which was operated for a limited
period of time, in an area with
a deep water table, where results
of soil testing indicate complete
biological degradation
o See footnote #2
o Old steel tanks (e.g., >10
years old) installed without
external or internal coatings
or cathodic protection, which
have not recently been leak-
tested or had an internal in-
spection by a qualified inspector
o Steel tanks which have been in
frequent or constant contact with
ground water for a relatively
long period of time
o Steel or fiberglass tanks for
which recent internal inspection
and/or leak test indicates lack
of tank integrity
o Relatively new, well designed
tank (e.g., cathodically protected)
storing highly corrosive and/or
highly mobile or toxic wastes, in
an area with high water table and
nearby downgradient drinking
water wells
o Outdoor pile containing relatively o Indoor pile with no free liquids
mobile wastes, not situated on a
liner or base, in area with porous o
soils and/or shallow aquifer
o Relatively new, well designed tank
(e.g., external and internal epoxy
coating and cathodic protection)
storing non-corrosive and/or
relatively non-mobile wastes/con-
stituents, not likely to come in
direct contact with ground water
o Tank with full secondary contain-
ment (e.g., vaulted tank with
leak detection system)
o Tank with recent internal in-
spection and/or "state of the art"
leak test which indicates that the
tank is sound
o Relatively new (e.g., <10 years)
metal tank storing compatible
wastes (e.g., solvents) in an
arid area with clay soils
o Large outdoor pile containing wastes
with particularly toxic constituents,
with physical evidence of sub-
stantial migration of wastes outside o
the containment structure, in area
with nearby downgradient drinking
water wells
Covered outdoor pile situated on
impermeable (e.g., well engineered
synthetic or concrete) base with
adequate containment system for
run-on and run-off
Outdoor pile containing relatively
non-mobile wastes (e.g., certain
fly ashes) situated on clay soils
in area of deep water table
-14-
-------
round Tanks
Container Storage
D^t
Above Ground
Tanks
o Relatively old concrete tank con-
taining large volumes of wastes,
with visible and substantial
deterioration of exposed walls, or
for which recent internal inspection
indicates serious cracking
of walls or other signs of
serious deterioration of
concrete
o Large concrete tank with no
protective internal coating
or liner, holding highly toxic
and/or mobile wastes in area
of high water table and
downgradient drinking water
wells
o Tank with visible evidence of
extensive soil contamination
fron apparent (or recorded)
overflow events or other oper-
ational or structural failures,
in area with porous soils
o Containers stored outdoors on
bare soil, with visible signs of
substantial soil contamination,
in area of porous soils and/or
shallow aquifer
o Outdoor area on which very large
volumes of waste containers have
been stored for relatively long
periods of time (e.g., >10 years)
with improper storage practices
(e.g., open containers) and/or
inadequate containment structures,
with downgradient drinking water
wells and/or highly toxic/mobile
wastes
o Large, outdoor metal tanks
situated on soil surface with
visible structural deterioration,
holding highly mobile and/or
toxic wastes, in area with shallow
aquifer and downgradient drinking
water_ wells
o Old, outdoor tank with visible
evidence of massive soil con-
tamination due to apparent (or
recorded) overflow events, in
area of porous soils
o Relatively small tank with
adequate liner/coating, with
record of frequent inspections
and maintenance schedule
o Relatively new, lined/coated
tank in good condition, with no
evidence of releases
o Indoor container area with adequate
containment structure
o Outdoor storage area with adequate
containment system, with no
visible" evidence of contamination
o Relatively small outdoor area
where waste containers were placed
for only a short period of time,
with no evidence of serious
contamination
o Small, indoor tanks with secondary
containment
o Outdoor tanks elevated above soil
surface, with secondary containment
structures
o Outdoor tank in good condition
situated on concrete pad, with no
visible or recorded evidence of
substantial release
-15-
-------
o Large tank situated on soil
surface, for which recent internal
inspection indicates severe
corrosion on bottom,'in area of
vulnerable hydrogeology
Incinerators o Outdoor incinerator with o Indoor incinerator with no
visible evidence of surrounding apparent evidence of significant
massive soil contamination releases to outside environment
resulting from apparent system/
operation malfunction
Footnotes:
I/ For such units, monitoring data should be carefully examined for evidence of ground
water contamination; this is of particular concern for units which stored only
characteristic waste.
2/ Class I wells inject hazardous wastes beneath the lowermost formation containing
an underground source of drinking water (USDW) within one quarter mile of the well
bore. The Agency realizes that there are concerns associated with installing
monitoring wells (often deep into the earth's crust) to detemine whether Class I
injections are adversely affecting USDWs, including the uppermost aquifer. Such
concerns include: the length of time (e.g., hundreds or thousands of years) it
Cy take to detect a release frcm the injection zone to the monitoring wells; and
e risks associated with installing deep monitoring wells which could later serve
conduits for the rise of injected waste into useable aquifers. Therefore, the
Agency has provided discretionary authority to the State underground injection
control (UIC) Director to require monitoring wells only when he beieves them to
be necessary. In such cases the Director will prescribe the number and location
of monitoring wells and the parameters to be analyzed.
The Agency is gathering additional information on the fate of Class I
injections. For example, an evaluation will be made to develop procedures that
can be used to identify when Class I injections have migrated beyond their
permitted injection zones. Until such procedures can be developed, the Agency
will continue to limit the circumstances under which monitoring wells will
be required.
-16-
-------
APPENDIX 3-1. SORPTION EQUILIBRIUM CONSTANT AS
EXPRESSED BY WATER-OCTANOL PARTITION COEFFICIENT (Kow)*
WEB «BST KAflE OF KAS7E HATERIAL
SYS t
75-15-0 CARBON BISULFIDE
103-90-7 CHLOROSENZEME
1319-77-3 CRfSOLS
95-50-1 1,2-DICHLORDBENZENE
75-09-2 BE7HYLENE CHLORI3E
75-69-4 TRIWLCR3MNOFLUOROBE7HME
B-S3-1 ISOBUTYL ALCOHOL .
78-93-3 BE7HYI E7KYL KE7CNE •
93-95-3 ' «I7fiC8E«:E,'c
110-S6-1 FVRJDiKE'
r
54-23-3
TETRACHLQflOETHYLENE .
CASS3JI TETKiCriLflfiiCE
106 K CK
2.S7
1.26
2.52
0.74
0.30
1.90
O.o3
Z.QZ
CHEM «3S7 NAKE OF KAS7E «A7ERIAL .
SYS t
LG5 K Ci
1327-53-3
13C3-23-2
542-62-1
593-31-2
502-01-3
107-20-0
544-92-3
57-12-5
460-19-5
506-77-.4
69i-23-4
492-42-2
ARSENICIVJOIIBE
AfiSENICIIIIiailDE
BARIUM CYfiMIDE
BRCflOACETOSE
CALCI'JB CYANIDE
CHLORMCETALDEHYDE
COPPER CYAK1DES
SDLUBiE CYANIDE SALTS K.C.S.
CYAN05EN .
CHL3RINE CVhMJE
DIETn'ilnRSJ'iE
0.40
-- r.
79-Jl-i
95-9S-4
es-Oo-2
TRICHLDSJE'HvlESE
"2,4,6-TRICHLOROFHE.WL
FENTACHLQSdFKESOL
- ETHYLEE.'uEN'E
3-3 ALLMIflUH FHOSPHJIE
-4 ARSENIC ACID
3.53
5,06
3.10
3,34
10102-43-9 NITRIC CrlC;
10102-44-0 NI7R02EN .'13., IDE
1C544-72-6 "KlTRSSEfJ IIKIIE
75-44-5 FHCS3E,\E
7SQ3-51-2 FHCSPH1NE
15L-50-3. FGTA3SILTI CYAMIE
506-61-6 - F07AESILT1 SILVER CYflNIDE
536-64-9 SILVER CYANIDE
* Note: Low value indicates greater mobility; high value
indicates lesser mobility
Expressed in log values
-------
CHEK CBST NAKE OF HASTE MATERIAL
SYS I
143-33-9 SODIL'n CYANIDE
57-24-9 STRYCHNINE AND SALTS
557-21-1 IINC CYANIDE
75-3i-5 ACETYL CHLGSIDE
79-10-7 ACRYLIC ACID
93-09-9 BEHZEKEs'JLFGJIYL CHLCSIDE
-353-50-4 CARBC'IYL FL'JCRIJE
3165-93-3 4-CHLORG-G-TCLUI2INE, HYCRSCHLGnlSE
64-13;6"
LOS K CM
-0.05
0.39
0.19
1.93
-04-4 HYDP.CSEN SL'LFIDE
/j
» T r
-»J~fc. **t •< i n i w i •
636-21-5 O-T;-::':::;,E HV:RC:HL:S
;06-t;-3 CVAfiCSEN CAO.IIIE
7t • ^ -" ^ • * "•il T P
TiWwa-i nriiiiilL
3l-3i-2 Bh'.FARIM
309-uv-2 ALJSIN
ic7-:s-s ALLYL ALCCH:L
7440-41-7 EEr.YLLI!J!1 DUST
2.05
-0.22
CHEN A3ST KAflE CF HASTE HATERIAL
SYS I •
542-23-1 BIS- (CHLORQflETHYL) ETHER
357-57-3 BRUCINE
33-35-7 DINC3EB
60-57-1 D1ELDRIN
293-04-4 DISULFOT3N
311-45-5 DIETHYL-P-WITROPHENYL FKCSFHATE
•51-23-5 2,4-DINITF,CFK£NOL
115-29-7 ENDOSULFAN
62-74-8- "FLliaRSACSTjQ.ACID.KDiaa.SALT
60-34-4 " J1ETKYL MuRAIINE
116-06-3 AL5ICAF.S
2*3-00-0 RETKVL FAFATHIuH
20cia-12-v Giillufl TE.r.uiUE
62-32-4 FHENYL r-F.CliSIC ACETATE
52-35-7 FAIPK'.R
107-19-7 P5GFARSYL ALC2HOL
2-6623-22-3 S3DIUH AZICE
73-00-2 TETRAETHYL LEAD
LQG.K.CH
1.06
0.10
4.07
1.92
-0.71
-O.II
i.;:
1.95
-i.o?
-------
AS5T mi OF HASTE IWTERIAL
S I
7446-18-6 THALLJUHUJSUlfATE
1314-62-1 VANADIUH PENTOIIDE
1314-84-7 ZINC PHOSPHIDE
79-06-1 ACRYLAflUE
107-13-1 ACRYLONITRJ1E
30-07-7 HITOMYCIN C
62-33-3 ANILINE
223-31-4 BENZ(C)ACRIDINE
36-53:3 "BEKZiAJASTHRACENE
50-32-3 ' c£N'ZC(A;PYR£?i£ ' _
74-33-9" KETHYL BROMIDE
. «MIT«».«I
i OVi iHiiul
. •••«,«i.«tifcir., t r.cinn. ;incn
•.•a-'/!-* (.rinfsE'iE
123-73-9 ;."OT3SALD£HV:-£
so-:?-3 . ;DT ~-
33-70-3 2IS£'u"CiA,H!A?iTHf!AC£N£
139-55-?' l.:,7,3IIBEWOPYRESE
?4-i:-3 i,:-DiBRcaa-:-£HLD«OFF.:FssE
106-93-4 ETHYLEHE DItRGflllE
764-41-0 l,4-DICHLORu-2-3UT£N£
1415-30-1 N,N'-D1ETH/LHYDRAZINE
O.SS
0.07
-:.42
0.93
6.16.
1.09
O.S7
L42
4.33
'2.13"
1.63
1.73
DO ABST NAflE CF WASTE HATERIAL
SYS t
36-33-1 DIETHYLSTILBESTROL
77-73-1 DIMETHYL SULFATE
123-91-1 1,4-DIGIANE
75-21-3 ETHYLENE OI2DE
110-00-9 FURAN
302-01-2 HYDRAZIKE
193-39-5 IHDENCn,2,3-CD}PYREKE
7439-97-6 HERCuRY
67-36-1 " KETHANOL -
91-SO-5 flETHAPY'RILENE "
56-49-5 3-flETHVtCHuLANTKSENE
101-14-4 4,_4-!!£THYLE.'lE-3I3-i:-DiLCWANlLIKE)
79-46-9 '
930-53-2 n-N!Tf;:£";i;L;;;fiE
82-=s-3 PEMTACHLCSCSITSOEEB:
2355'J-S2-5 PRC-'^lCe
30-55-3 ft£SEF.F!.'i£ '
62-36-6 THICL'?:£A
66-75-1 URALlL .TuSTARJ
31-J9-6 EIHTL CAS2A3ATE -
13931-37-8 NI^EL
616-23-9 2,3-51CHLGRCPRu?AffCL
LOG.K.OK
3.04
0.06
-0.03
-0.77
1.34
6.62
6.93
3.?6
.4.39
4.31
-0.15
0.30
-------
CHE,". AB3T NAJ1E OF HASTE MATERIAL
SYS I
96-18-4 1,2,3-TRICHLOROFR3PANE
7440-36-0 ANTIrtONY
203-96-3 ACENAPHTHYLENE
2C5-97-2 BENZO(B)FLUCRANTHENE
12002-48-1 TRICHLOROBENZENE
122-39-4 DIFHENYLAfllNE
1C8-45-2 H-PHENYLENEDIAKINE
118-96-7 TNT ..
551-C3-2 " flCEIWUBE, JJ-!AfilNOTHI3I3flETHYLl-
L36 K
:-96-4 5-(A,1IHCr>£THYL)-3-I30:A;:LCL
504-14-5 <-AHINO?YRIEISE
1.85
3.30
3.65
-0.30
2.40
-0.87
0.88.
-0.20
-0.36
757-58-4
16752-77-5
75-55-3
86-38-4
152-16-9
298-02-2
1314-96-1
107-49-3
509-14-3
1314-32-5
12039-52-0
8001-35-2
5344-51-1 i-.3—3HLG?.urKE:i'i'L) T4iIu;j?.£A
277-97-2 C.3-DIETHYL C-PYFAZINYL FHQSFHCS3THI3ATE
55-91-4 DIISCFRQFYL FLU3RuPH33?HATE
60-51-5 "DI.^ETHuATE -
541-53-7 2,4-DITH!:SIuRET
15L-56-4 A::RIDI»E
64C.-19-7. ACETA.11JE. :-FLL13Ra- . .
76-44-3 HErTACHLOR
JiC.^^.L TC"nOTU
^8J iw 0 4•UyrtiH
.1.15
3.33
-1.00
-0.35
.-1.10
-i.12
4.77
CHE.1 ABST HAflE DF «A2TE MATERIAL
SYS t
KEIAETHYL-TETRA-FHQ3PHATE
HETHOflYL
2-KETHYLAZ1RIBINE
ALPHA-NAPHTHYLTHICUREA
OCTATITHYLFYROPHOSPHCRAfllDE
PHORATE
STRGNTIUil 3ULFIDE
TETRAETHYLFYR3PHOSPHATE
TETF.ANITRQBETHANE-
THALLIC CHSE "
T»ALLIL'ntl;S£LEfJITE
TDXftFhENE
136 K CM
il'J^i 1C, IL1
at-a-i
75-05-3'
:3--s-3
L i ^^_jc * w * wf>f*\ r
61-3i~3 HHiinuLt
492-80-3 AUP.ASIHE
115-02-6 AZASEF.I.NE '
71-43-2 BENZENE
92-S7-5 SENZID1NE '
9B-i7r7 . BENZOTRICHLCSIDE. -
111-44-4 . DICHLCROETHYL ETHER
494-03-1 CHLCRNAPHAZ1NE
-0.57
1.95
6.23
0.79
4,14
1.04
-------
CHEJ1 AB5T
SYS *
117-31-7
13745-19-0
305-03-3
37-74-9
75-01-4
67-64-3
91-58-7
108-94-1
50-18-0
20830-81^3
!:<-!
W- •• i
Twvw-iO"*
91-94-1"
HAKE OF HASTE MTERIAL LOSJ.W '
BI3(2-ETHYLHEIYL)PHTHALATE *4.00
CAIC1UH CHR5HATE
CKLQRAKSaCIL
CHLOR2ANE, TECHNICAL
VINYL CHLCRIDE 1.38
CHLOROFORB 1.94
BETA-CHLGRNAPHTHALENE 4. OS
CVCLOHEIA-'iOSE 0.84
'CYCL3PJ10SPH*1IDE
OA!»s.mn • ' -
DSD .
DIALLSTE
^ Ti «»/*•'» rt^^^PiifTW**!?* * f*
J|W *^AWnCUI\UvCi^4Ai/il^C W«J™
CHE.1 S8ST
SYS 1
105-47-9
121-14-2
404-20-2
117-84-0
122-44-7
142-84-7
-421-44-7
111-54-4
96-45~-7
42-3C-0 '
50-00-0
113-74-1
KAKE OF HASTE KATERIAL
2,4-DI«ETHYLPHENOL
2,4-OINITROTOLUENE
2,6-DIKITROTOLL'EKE
CI-H-CCTVL PHTHALATE
1,2-DIPHEHYLHYORfiIIME
CIFRaPYLAHIfiE
OI-M-PftOFYLJiITRC3A«lNE
ETHYLENE-BI3-(DITHIOCASBAf!IC ACID)
'.ETRYLLH: THKMEA
ETHVL BEffiSaESiKr-BSKTE .
FORMLDEHYIE
nc« HL^Uflth.6..E
LCG.K.
2.31
2.30
2.30
"4.00
3. CO
1.47
1.42
• 0.31
0,09
s.4:
4.i7
78-37-5
40-11-7 JlBETKYLnBINGAZOBENZENE
57-97-6 7,12-DIKETHYLBENZtA)ANTHRACENE
117-73-7 3,3>-01.tE;HYLB£NZIDIM
7?-44-7 CinETHYLCARBABOtL CHLOFISE
57-14-7. 1,1-DinETHVLHYSRAZINE "
540-73-3 1,2-DIJiETHVLHYDRAZINE
1.94
7.02
2.3u"
l.Gi
-1.47
47-72-1 n£AACrL:=:rH^E
74-38-4 flETHTL Iu::ii
143-50-0 KEFCiE
30L-04-2 LEAD ACETATE
109-77-3 f!AO!SGNlTSILE
148-82-3 MELPHALAN
108-10-1 .1ETHYL I:3BUTYL KETCNE
i.. "3
-i.n
1.25
-------
AEST NA!1E OF HASTE flATERlAL
t
SO-42-4 KETHYL HETHACRYLATE
70-25-7 N-HETHYL-H-NITRO-N-NITRaSCSUASIBINE
56-04-2 KETHYLTHIOURAC1L
91-20-3 NAPHTHALENE
91-59-3 2-NAPHTHYLAMINE
100-02-7 P-HITR3FHENDL
.924-16-3 N-NITROSC-DI-N-BUTVLA.IINE
1116-54-7 N-HJTRQSC-SI-ETHftNCLABiNE
--
18-
' K-NITR.OSG-Sr-ETHiLAHINE
759-73-9" N-NlTRCSO-N-ETKYLi;?,EA
615-53-2' N-NlTRCSG-N-flETHYLDr.ETHANE
-y'LF ILE
7433'5i-4 SELE.'lIiJH Si;jL"I2E
13E33-QO-* STREFT:::^
79-34-5 " 1,1,2,2-TETRACHLGRCETHANE
rt^_'" 3 ^U5! f TP» i * l <"
-------
,cfl ASST NAflE OF HASTE JIATER1AL LCS K QV
SYS 4 ,
72-20-8 ENDR1N
624-83-9 BETHYL ISQCYANATE 0.39
628-34-4 HEfiCURY FULKINATE
13463-37-3 NICKEL CARBSNYL
54-11-5 NICOTINE ANB SALTS l.i;
100-01-6 P-NITRCAMILINE 1.32
145-73-3 ENDOTHALL
103-S5-5 N-PHENYLTHIOUREA 0.77
107-12-0 " PROPANENITF.ILE . Q.16
630-10-4 SELErJOURcA
3oe?-24-5- TEiRncTHfiHITHIuFYRur'KCSPKATE
514-42-3 Tr.ICHLCr.unETnni'iETHIiL l,ai
98"36-2 nCETuFHEIfC.'iE 1.61
09.57-T C'CM'il T2!nBf-r •*• 11
/o c/ w fikiiiML tnL..>i«c ^.24
lll-il-l EIS(2-CHL2RuETKCAt)fi£THnHE ' 0,-SQ
1C3-60-1 EIS12-CHLCRGIS3PROPYL) ETKES 1.43
75-^7r6 . CHLCRAL . . - L.66
510-15-6 - ETHYL-4,4'-DICHL2R3BENZILATE 4.41
59-50-7 4-tHLQF.O-fl-CrE3QL 3.16
CHE.1 A£ST KAHE CF HASTE RATERIAL
SYS t
110-75-3
74-37-3
95-57-3
92-B2-3
110-92-7
74-95-3
84-74-2
541-73-1
106-46-7
75-71-8 .
75-I4-3 .
156-60-5
1IO-E3-2
2-CHLQROETHYL 9INYL ETHER
HETHYL CKLORJSE
0-CHLCRCFHENOL
CUKENE
CYCLCHEIANE
HETHA.NE, DISRMO
DIBuTYL PHTHALATE
1,3-lICHLOROBENZENE
CICHLK'CDIFLuuR'OKEThhiiE
ETHANE, L,1-D1CHLOR3-
1,2-DICHLOROETHYLENE
2,4-uICHL.RjrHeNuL
1464-53-5 2.2'-3ICJ;RANE
3235-53-2 0,0-31£ThVL-S-f;£THVL-;iTK::?HC£.:r.;:E
84-66-2 DIETHYL FHTHALATE
94-53-6 OIHYDRCSAFRGIE
S0-J5r9 . ALPHA,Ai.FHfi-SIKETHYL£ESL-:y:SjrEftGSIlE
131-11-3 [METHYL FHTHALATE
141-78-6 ETHYL ACETATE
2.25
C.75
? ^?
3.77
1.42
1.54
2.08.
1 0*
1 . u«
2.?!
. i.73
t " ^
*~*v
1.56
0.71
-------
CHEH ABST NAUE CF HASTE HATERIAL
SYS t
140-33-5 ETHYL ACRYLATE
60-29-7 ETHYL ETHER
97-63-2 ETHYLflETHACRYLATE
2C4-44-0 FLUGRANTrOE
98-01-1 FURFURAL
763-34-4 6LYCIDYLALIEHYDE
77-47-4 HEIACHLORQCiCLOPENTALiENE
70-30-4 HEIACHLCRCFHENE
90C4-66-4 "IRCN DEITRAJf
33-1 ' ISuSAFRjLE
-27-7 LEAD PHC3FHATE '
103-31-8 «AL£Ii AWitDSIii
LOS K CM
1.32
0.92
1.64
4.93
1.00
4.27
*6.00
:.45
0.14
B3-44-9
109-06-3
107-10-3
104-51-4
103-46-3
81-07-2
•95-94-3
75-25-2
99-35-4
72-57-1 "
94-73-7
1333-71-7
CHEfl ABST NAflE OF ilASTE SATERIAL '
SYS t
PHTHALIC ANHYDRIDE
2-FICGLIIlE
1-PROPANAHINE
F-SEN205UINONE
RE30RC1XAL
SACCHARIN AND SALTS
1,2,4,3-TETRACHLCROEENIENE
BRGUCFCSn
'.SKn-TRINITRCBENIENE
TRYPAN_SLJ£
HEIACKLSRSFRCFESE
LCG.K.
1.32
1.34
0.43
-0.61
•\ r^
C.Ci
5.00
2.33
1.33
134-32-7 • 1-MAPHThiLAflIKE
97-55-3 5-KITRO-Q-TDLUIDi;i£
123.-63-7 PARALIEHYIs
76-01-7 PEMTACHLC.vSETHANE
304-60-9 1,3-FENTA:;EKE
62-44-2 PHENACETIN
1.12
2.11
1.93
1.06
1.S4
•4:?-;:-i LEAD
- FE^RI: FE-?.:CVANI:E
-------
APPENDIX 3-2
LISTS OF GROUND-WATER MONITORING PARAMETERS
LISTS A, B, C
-------
LIST A
Parame ter
sodium
calc i urn
ma gnes i urn
sulfa te
chloride
pH
total organic carbon
total organic halogen
total p henols
1»1,1-trichloroethene
lead
cadmi urn
Chemical Abstract System Number
7440-23-5
7400-70-2
7439-95-4
71-55-6
7439-97-6
7440-43-9
-------
LIST Bl
INDUSTRY SPECIFIC PARAMETERS
METALFINISHING
Parame ter
chromi urn
copper
cyan Ide
iron
zinc
trichloroethene
tetrachloroethylene
vinyl chloride
phenan threne
nickel
Chemical Abstract System Number
7440-47-3
7550-50-8
57-12-5
7439-89-6
7440-66-6
79-01-6
127-18-4
75-01-4
85-01-8
-------
LIST B3
PESTICIDES
Parame ter
Chemical Abstract System Number
arsenic
cyanide
copper
benze ne
carbon tetrachloride
chlordane
chlorobenzene
chloroform
1,4-dIchlorobenzene
2,4-dichlorophenol
hep tachlor
hexachlorocyclopentadiene
methyl chloride
methylene chloride
4-nitrophenol
phenol
tetrachloroethylene
toluene
Manufactured pesticides*
7440-
57-
7550-
71-
56-
57-
67-
108-
106-
120-
76-
77-
74-
75-
100-
108-
127-
108-
•38-2
•12-5
50-8
•43-2
•23-5
•74-9
66-3
•90-7
46-7
•83-2
44-8
•47-4
87-3
•09-2
02-7
95-2
18-4
88-3
*Any specific pesticides, residues, off-specification products,
or other slmiliar Items known to have .been disposed of at the
site, or, in the case of a dedicated facility, known to have been
manufactured at the site.
-------
LIST B2
IRON AND STEEL
Parame ter
arsenic
ch romi urn
cyan ide
tin
zinc
benzene
benzo(a)pyrene
tetrachloroethylene
Chemical Abstract System Number
7440-38-2
7440-47-3
57-12-5
7440-31-5
7440-66-6
71-43-2
50-32-8
127-18-4
-------
Parameter
bis(2-ethylhexyl)phthalate
PCB-1016
PCB-1221
PCB-1232
PCB-1248
PCB-1254
PCB-1260
PCB-1242
a rsenlc
benzene
chlorobenzene
ethyl benzene
toluene
chromium
copper
cyanide
tetrachloroethylene
vinyl chloride
trichoroe thylene
iron
ma nga ne se
naph thalene
nickel
phenan threne
phenol
zinc
LIST C
Chemical Abs trac t Sys tern Number
117-81-7
12674-11-2
11104-28-2
11141-16-5
12672-29-6
11097-69-1
11096-82-5
53469-21-9
7440-38-2
71-43-2
108-90-7
100-41-4
108-88-3
7440-47-3
7550-50-8
57-12-5
127-18-4
75-01-4
79-01-6
7439-89-6
7439-96-5
91-20-3
7440-02-0
85-01-8
108-95-2
7440-6-6
-------
SECTION ONE
PLANNING AND CONDUCTING THE
SITE INVESTIGATION
I. INTRODUCTION
The site investigation (SI) is the second phase in evaluating
SWMU's for releases to the environment. The SI builds upon the
data collected during the preliminary assessment (PA) and in
general involves collecting new information through visual observa-
tion. Where appropriate/ the SI can also involve sample collection
and analysis.
The purpose of an SI is to: (1) identify units/facilities
that pose no problem, (2) prioritize facilities for further in-
vestigation, and (3) identify the scope of subsequent remedial
investigations or immediate corrective action. This will be
accomplished by evaluating the potential for exposure to humans
and the environment via surface water, ground water, air, soil,
and subsurface gas.
As a rule, the SI takes considerably more time than the PA
to complete. Unlike the PA which involves mostly desk work, the
SI involves both desk and field work.
The scope of the SI involves collecting additional data
through a comprehensive visual survey and, at some facilities,
sample collection.
1-1
-------
This chapter of the Corrective Action Guidance will address
the overall process involved in conducting a SI—beginning with
supplementary background data collection through writing a final
SI report. Each section of this Chapter will discuss the various
steps involved in performing an SI. These steps are identified
in Figure 1. The evaluation stage will not be discussed in
this chapter. It is the subject of the succeeding chapters.
II. BACKGROUND DATA COLLECTION
The purpose of this step in the site investigation process
is to gather the data necessary to prepare a work plan, safety
plan and sampling plan (if required) for the facility and possibly
collect site data not developed during the PA. Most of the
time, if the PA was performed properly, it should not be necessary
to collect additional site data. However, if there are significant
gaps between the time the PA is completed and the SI begins then
it may be necessary to update PA information. In another instance,
the background data simply may be lacking in some relevant data
that should have been collected during the PA. If additional site
specific data must be collected, this should not take a lot of
time, on the average.
The more thoroughly this stage of SI is done the more focused
the field activities will be and the less field time and resources
it should take. If key data is missing in the four categories
identified in the guidance on preliminary assessments especially
(1) waste charcterization (2) designated operational characteris-
tics, and (3) migration pathways characterization, the reviewer
should determine if all possible sources of the information have
1-2
-------
FIGURE 1
STEP-BY-STEP BREAKDOWN OF A SITE INSPECTION
Background Data Collection
Work Plan/Sample Plan/Safety Plan
Development
Work Plan/Safety Plan/Safety Plan
Review Procedures
Mobilization
Access/Community Relations
Comprehensive Visual Inspection
Sampling Inspection (if required)
Sample Analysis/Analytical Data Review
Data Evaluation
Write Report
Report Review
-------
been considered. These pieces of information are perhaps the
most important data needed to conduct an effective and efficient
site inspection. Information on the nature of waste disposed
in each unit is essential to determine if it is even necessary to
pursue evaluating a unit or facility. If there are no wastes
of concern, then it is not necessary to proceed further. Waste
data will guide the inspector in what to look for if sampling is
performed. The design and operational data and physical geography/
geology of the site is essential to identifying whether there is
a possibility for a release from a unit, how quickly materials
will release and, if so, where to look for the release.
This information is invaluable in focusing SI field efforts,
especially sampling if it is necessary. For example, certain
types of compounds tend to preferentially migrate via surface
water sediments or ground water; i.e., heavy metals and higher
molecular weight organics. Where this occurs, it would be
unfruitful to look for releases of such constituents in the
aqueous phase of surface water. Other materials tend to bind
extremely well to certain soil types and are essentially contained
in the site. Others do not bind well in certain soils or photo-
degrade. These materials are not likely to be observed away from
the surface.
At this stage, if gaps in data remain or the data collected
is not sufficiently detailed to be of use, then the owner/operator
should be directed to provide this information. For example,
USGS maps may not be sufficiently detailed to understand where
contaminants may migrate, or information previously submitted by
the owner/operator may be too general. The inspector should
-------
develop a list of data gaps and request, by letter, the owner/operator
to submit the information. The letter should be as specific as
possible, identifying the type of information requested, the
source (or possible sources) of the information, and the due date
for the response.
After all sources have been exhausted, it is possible that
gaps in data may persist especially data on old abandoned SWMUs
that have changed ownership a number of. times. Where these data
are absent or inadequate then the SI field work will tend to be
larger and broader in scope, generally involve more sampling, and
require the more comprehensive full priority pollutant analyses.
Data gaps may also 'lead the inspector to decide that all further
investigations should be conducted by the owner/operator as part
of an RI—the purpose of which is to obtain the data to decide
if a release of concern is likely.
After all available information describing facility-specific
units, features, and waste types is collected, the reviewer will
need to consider technical/non-site specific data that will de-
tail the chemical, physical properties of waste and the physical
environment. This information is necessary to determine:
(1) what the characteristics of the waste type indicate
about the route via which the waste will preferentially
migrate (i.e. via air, surface water, soils, ground
water, subsurface gas or some combination of these)
(2) what the characteristics of the surrounding environment
—soils, geology, hydrogeology, weather, indicate about
the rate of contaminant migration (i.-e. will soil typee,
geology, hydrogeology, or weather contain, slow, or
facilitate the migration of contaminants),
-------
There are two prime sources of information describing waste
and physical environment characteristics—reference materials and
periodicals. At the end of this chapter are some useful reference
materials.
Appendix A is a list of the more volatile and hazardous
constituent associated with certain industry's wastes.
This will assist the reviewer in identifying which volatiles
to look for with the portable field instruments (Hnu, OVA,
detector tubes) and what gases to use in calibrating the
instruments.
Appendix B^ List B is a list of ground water monitoring
parameters for a handful of industry types. This list
will identify the contaminant characteristics of certain
industries which one Is likely to detect and, therefore,
analyze for in ground water.
1-6
-------
Appendix ^. is a list of commonly identified pollutants and
where one might expect to find the contaminants if they have
been released into the surface water route.
r
Also attached as Appendix J-L-is a list of other standard " ,->
reference manuals too large to be included in this guidance that
are also useful in characterizing the waste and physical environ-
ment and a cryptic identification of the type of information the
reference material provides.
Most of this information will be used in the development of
the sampling and safety plans as well as data interpretation.
For the sample plan development, the reference material will aid
in locating optimum sampling locations and determining which
constituents to analyze for. For the safety plan development,
the reference material coupled with prior experience with the
facility, will aid in identifying the type of protective clothing
needed and the appropriate respiratory protection.
III. PREPARATION OF WORK PLANS, SAFETY PLANS, AND SAMPLING PLANS
After all the necessary data has been collected, work plans
and safety plans must be prepared. If sampling is required, a
sampling plan must be developed. The plans document the proce-
dures to be used, the resources needed and the rationale for the
activities to be undertaken. These documents insure that all the
necessary planning, preparation and review has been done before
field work begins. They provide a basis for later interpreting
the results of the site inspection and documentation of the
procedures and technical approach used in the event of future
enforcement action.
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A. Work Plan
The work plan is the umbrella plan that pulls all three plans
together. The work plan provides for the efficient scheduling of
resources such as manpower, equipment and laboratory services. •
The work plan should include the following:
o Introduction. This section should briefly describe (a.
few paragraphs) the facility and the objectives of the
SI—i.e. conduct visual inspection, collect samples, etc.
This section is for the benifit of the person reviewing
the plan and to document the rationale in the event of
future enforcement action.
o Investigation procedures. This includes identifying the
specific standard operating procedures (SOPs) and field
quality control (QC) procedures to be used. Appendix 3>
contains an example check-off list of SOPs and QA proce-
dures to be used in during the field work. Use of a
check-off list prevents weighting down the work plan with
"•"- reams of boilerplate SOPs. If the owner/operator is
collecting the samples, a copy of the SOPs and QA procedures
should be provided.
o Personnel requirements. This identifies all persons needed
to conduct the field activities including support person-
nel and their specific responsibilities.
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o Equipment requirement. All safety and sampling equipment
and supplies should be identified plus any other support
or non-standard equipment and supplies. Attached in
Appendix £. is an example equipment list.
o Contractual services. Any contractual services needed to
accomplish the field work.
o Waste disposal procedures. All waste generated as part
of the site investigation activities, such as disposable
suits, gloves, sampling materials, must be disposed of in
an appropriate manner in accordance with RCRA regulations.
(In most cases it should be possible to get the owner/
operator to agree to dispose of the waste material at his
facility.)
o Special training requirements. If any new equipment or
procedures are to be use then mini training should be
arranged.
Special consideration must be given to aspects of the work
which may vary greatly from site to site. Each one of the follow-
ing areas can'greatly affect the time, expense, manpower and
equipment needed for the project.
' o hazards - What physical or chemical hazards may be en-
countered? Are there open manholes, deep embankments, low
power lines, methane gas vapors, deteriorating surface
features, poison ivy, snakes? Is the facility especially
large?
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o facility location - How far is the facility from the home
office? Will samples need to be shipped by overnight
courrier to the laboratory? How far away is the nearest
overnight shipping office? How accessible is the facility,
especially inactive areas?
o timing - Can the facility be visually inspected or will
snow obscure facility features? Will the surface waters
or ground be frozen such as to limit sampling? Will work
performed in the winter be limited by short daylight
hours? Will work performed in the summer wear out field
personnel quickly? How will the season of the year
affect water levels? Will leachate springs be visible
during the dry season?
B. Sample Plan
Not all sites will be sampled during the SI state therefore
in some situations in will not be necessary to prepare a sampling
plan. If sampling is required, the following is a discussion
of the plan's contents.
1. Contents of Sample Plan
It will always be the responsibility of EPA to prepare the
sampling plan and the investigation procedures portion of the
workplan, regardless of whether EPA or the owner/operator actually
performs the sample collection. This will minimize or eliminate
the risk of bias that could be introduced by the owner/operator
during the sample collection and analyses.
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The sample plan is encorporated into the work plan and
identifies the sampling locations, rationale and logistics. The
following outlines the contents of a sampling plan with a brief
discussion of each component.
o Field operation.
The sampling plan should discuss the sequence for conducting
the field activities. The specific functions of each individual
should be identified in the work plan. For example, specific
individuals need to be identified to take samples, maintain the
field log book, monitor the site with instruments, collect samples.
o Sampling locations/rationale.
As precisely as possible, the location of each sample
should be identified. A site map should be prepared to guide
the inspectors to the appropriate location. Each sample type
should be identified—soil, sediments, surface water, VOA, air,
ground water and whether the sample is collected for metal,
organics, BOD analysis, etc. The volume of sample to be collected
and the number of samples collected should be identified. A
justification for the selection of each sampling location should
be provided.
o Analytical requirements.
The sampling plan should discuss the specific parameters
for which each sample is to be analyzed.
o Sample Handling.
The preservation techniques and material for each sample
should be identified. If sample filtering is needed, that should
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be identified in this section including an explanation of its
use. The containers used for each sample collection episode
should be described including the tools, supplies, and equipment
needed to collect the samples. Any procedure not covered by
SOP's or different from the SOP's should be delineated here.
o Quality Assurance Samples.
The number and type of quality assurance samples should be
identified in the plan—specifically the number of blanks, dupli-
cates, or spikes. The "rules of thumb" for QA samples are dis-
cussed later in this section.
o Sample Decontamination.
The reageants and any special procedures associated with
sample bottle decontamination should be identified in the sampling
plan.
o Sampling reports/documentation.
The sampling plan should describe all sampling forms that
should be filled out Including chain-of-custody forms, sample
receipt forms, sample traffic reports, sample tags. If any split
samples are to be collected then instructions as to who should
receive the splits should be identified here.
2. Quality Assurance/Quality Control Program for Sampling
All samples should be collected in accordance with the
appropriate quality assurance (QA) and quality control (QC). QA
is the total program for assuring the reliability of monitoring
and measurement data. SOP's are the cornerstone to a QA program.
SOP's are the exact, detailed procedures for performing a specific
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task such as purging a shallow well, collecting a surface water
sample, etc. The SOP's insure that the methods, techniques,
and procedures for collecting technical data are correct and
reproducable. SOP's are developed by persons with considerable.
experience in the particular activity and represent the best way
to collect the sample for a specific situation. They also insure
that a person collecting the same type of sample somewhere else
or later on is performing it in the same way. This becomes
particularly important in interpreting the results of the sample
collection and in the defense of data in court later.
The field sampling activities should be supported by preparing
and submitting several sets of quality control samples. These
include blanks, spikes, duplicates, and splits.
o Blanks
There are two kinds of blanks of concern for this type of
work: trip blanks and field blanks. Trip blanks are used to
determine if inadvertent contamination is introduced from the
sample containers or from an activity other than sample collection
such as---sample shipment, storage. Blanks are prepared by the
sampler using distilled d-eionized water of known high purity.
These bottles are then sent with the othe sample bottles to the
field but are not opened. One set of trip blanks for each
analytical parameter group (e.g., organics, metals, volatiles)
should be prepared and submitted for each day of sampling at a
particular site.
Field blanks are used to determine if contamination is
introduced by the sample collection activities or sampling
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environment. They are prepared by bringing a quantity of dis-
tilled deionized water to the field and "preparing" a sample by
pouring the water into the bottles. They can also be prepared by
pouring the sample through sample collection devices such as
bailers. A field blank should be generated for each day of
sampling at a particular site.
Blanks should be submitted in the same manner as the other
field samples, with no distinguishing labeling or markings.
o Spikes
Spikes are samples to which a known amount of a compound has
been added and are used to determine if contamination or error is
introduced into samples as a result of laboratory procedures.
One spiked sample is recommended for every ten field samples.
Spiked samples are prepared by the laboratory performing the
analyses after the samples are received at the laboratory.
Although spikes are generally not handled by field personnel,
they are part of the QA process and should be specified in the
sampling plan.
o Duplicates
Duplicate samples are another method of checking on the
precision of a laboratory's analytical methods. One duplicate
sample should be taken for every ten samples collected at a
facility. Duplicates are prepared by collecting one portion of
sample, homogenizing it and dividing the sample into equal
portions.
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o Splits
Splits are identical portions of samples split between EPA
and the ownr/operator. Splits are required only if the owner/operator
is responsible for collecting and analyzing the samples. Split.
samples are used to evaluate the accuracy of analyses performed
by a laboratory. Splits are prepared in the field exactly like a
duplicate, but unlike duplicates, splits are always analyzed by
different laboratories. The owner/operator should be instructed
to prepare a split of all samples. The EPA inspector will then
select two samples for EPA to analyze from among all the samples.
C. Safety Plan
A safety plan should be prepared for each field visits. All
safety plans should be prepared in accordance with appropriate
EPA guidance. (See EPA's Standard Operating Guides (SOSG's) for
specific guidance on selecting the appropriate level of protection
and how to prepare a safety plan.) The safety plan is usually
prepared last and is tailored to the SI activities. For some
Sis, the safety plan will be very simple and require few protective
measurs-s. Other, more problemsome sites, may require use of
higher levels of protection. For example, if the SI involves
sampling lagoons then the safety requirements will probably be
more involved than an SI that involves simple visual reconnaissance.
Attached at the end of this section is Chapter 9 from EPA's
SOSG's. The SOSG's were prepared in accordance with EPA and
other Federal health and safety guideline, regulations and orders
This attachment discusses the steps involved in developing a
safety plan and elaborates on the contents of each section of
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the plan. Provided below is a brief outline of the contents of
the plan. Refer to the Exhibit at the end of this section for
more detail.
o Describe Known Hazards and Risks
o List Key Personnel and Alternates
o Identify Levels of Protection to be Worn
o Identify Work Areas
o Identify Access Control Procedures
o Describe Decontamination Procedures
o Describe Site Monitoring Program
o Identify Special Training Required
o Describe Weather-Related Precautions
IV. WORK PLAN/SAMPLING PLAN/SAFETY PLAN REVIEW PROCEDURES
Once the work plan, sampling plan and safety plans have been
prepared, the plans should be reviewed by
o other members of the team,
o designated specialists/informal peer review, and
o appropriate decision officials.
The purpose of this .internal review is to ensure that the
plans are complete, that the plans meet the goals of the site
inspection and that all the appropriate quality assurance require-
ments for the field work are met. Most importantly, the internal
review will assist in eliminating any unnecessary sampling and
ensuring the proper focus for the SI.
The other members of the team review the plans to first
understand their roles in the field activities and second to make
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sure all the appropriate safety and field equipment they will
need to perform their activity is accounted for.
The plans should also be circulated to individuals within
the office with specialties in the various disciplines associated
with the field work—geologists, geohydrologist, chemists, botan-
ists, engineers, occupational health specialist (safety officer).
These individuals will provide insights into areas with which the
person preparing the plan may not be well aquainted. They would
comment on the technical approach described in the plans to
insure that sound technical judgment is applied and double check
for any possible inadvertent mistakes or omissions.
Lastly, the plans should be reviewed and approved (signed)
by an appropriate decision official—at least a first line super-
visor. This person would be responsible for insuring that the
plan meets all Agency and internal requirements as well as meets
the goals of the investigation.
V. MOBILIZATION
In this stage of the SI all the necessary equipment and
supplies are collected, all the equipment checked to insure
they are functioning properly, all the appropriate pieces
available, and any arrangements for sample analysis are made.
If any additional supplies need to be procured they should be
done at this stage. Also, if any unique contractual or equipment
rental is required this should be done in this stage.
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Equipment check-out and callibration is a very important
task in this stage. Out in the field is not the time to discover
that the battery is dead, the OVA carrier gas is empty, or the
Hnu lamp is broken. Each instrument should be checked following
the SOP for that particular instrument. The day of or before the
instrument is to be used, the instrument should be callibrated.
At the completion of the checkout and callibration (1) the date
of callibration, (2) person checking.out or callibrating the
instrument, (3) the callibration standards used, and (4) a nota-
tion of deviation from SOP check out or callibration procedures
should all be noted in the field or instrument checkout logbook.
If the work plan specifies sampling, then it is necessary at
this stage to confirm the availablity of analytical space in the
laboratory, especially if samples will be analyzed by the EPA
Contract Lab Program (CLP).
VI. ACCESS/COMMUNITY RELATIONS
A. Owner/Operator Access
Prior to conducting the field work, the inspector must
contact the owner/operator to schedule a time for the SI team
to enter the site and perform the necessary field activities.
Although it is possible that there has been considerable contact
with the owner/operator about impending field work, the appro-
priate regional person should contact the owner/operator to
verify dates and the nature of the field activities—sample
collection, picture taking, facility inspection, instrument moni-
toring.
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If the owner/operator is responsible for collecting and
analyzing the samples, then the EPA official should contact the
owner/operator to schedule a date to oversee the field activi-
ties. The sampling plan and procedures for performing the sample
collection should be sent to the owner/operator sufficiently
ahead of time for him to obtain the appropriate support. If EPA
is collecting and analyzing the samples, EPA must offer the
owner/operator a split of all samples collected. If the owner/
operator wishes to have splits, he should be instructed to pro-
vide analytical sample bottles for the splits.
All arrangements should be followed with a letter confirm-
ing the dates and field activities. If access is denied, specific
guidance on what to do is provided at the end of this section in
Appendix £• _. L"TV
In some cases it may be necessary to access adjacent or
nearby properties in order to conduct a visual inspection or
collect samples. This may include industries and residents.
They too should receive verbal as well as written notification
of the dates and nature of the work.
Although the RCRA inspector is authorized to inspect a
facility and collect samples and photographs, the owner/operator
can require that the inspection and sample collection activities
be conducted to protect his or her rights. The admissibility of
data in court, should the owner/operator file suit against EPA,
may later be challenged if the data was collected in violation of
the owner/operator rights. For this reason, the inspector
should not appear or act in a coersive or threating manner. The
owner/operator is free to observe inspection activities, unless
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the owner/operator is interfering with the safe or technically
sound conduct of the site inspection.
The owner/operator has the right to request confidential
treatment of certain data. The inspector should avoid agreeing"
to this to the greatest extent possible since it poses a problem
with later using the information in public proceedings under RCRA
or even under CERCLA. It also poses a sizable burder on EPA to
control the data. If data deemed confidential by the owner/operator
is needed to properly evaluate the facility then a precise description
of the confidential data should be identified in the field log
book. The inspector should instruct the owner/operator to follow
up with a letter identifying the confidential data and and explaning
the reason why the data is business confidential. EPA regulations
governing treatment and handling of confidential data are delin-
eated in 40 CFR Part 2, Subpart B, Sections 2.201-2.309.
B. Community Relations
If it will be necessary to conduct any field activities in
or near residential or non-industrial business areas, then appro-
prlate"local officials should be contacted ahead of time. It is
difficult to remain unobtrusive while conducting site inspections
particularly if field workers are wearing protective clothing.
Moreover, the presence of "official" people collecting samples
can cause undue alarm. In some cases, it will be difficult to
prevent this but prior, well handled community contact can mini-
mize the alarm. Each of the regions has a community relation
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staff to deal with the public for hazardous waste site investiga-
tions. These individuals can assist in identifying appropriate
local community contact for a particular area.
The Office of Solid Waste is preparing guidance on community
relations that will be available later this year. This document
will provide specific guidance on when and how to implement a
community relations program at RCRA facilities.
VII. COMPREHENSIVE VISUAL INSPECTION
The scope of the field work can vary depending upon whether
sample collection will be needed. The field inspection may involve
at a minimum conducting a thorough visual inspection at the
facility to confirm information previously collected and to gather
more information about a facility where data is lacking. If
sample collection will be required, the SI will often be broken
into two stages—the first stage wil be to conduct a comprehensive
visual inspection to gather data about units and releases and to
identify prime sampling locations. The second stage will involve
collecting samples. If the owner/operator is collecting samples,
an EPA'person should be present to observe the activities to
ensure conformance to the work plan, record field activities
in the log book, resolve any field related problems that develop,
and ensure proper field quality control. In some cases, it may
be possible to eliminate EPA oversight in this phase of the SI
if EPA personnel are confident of the integrity of the owner/
operator and quality of his work.
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There are a host of different aspects associated with con-
ducting a field inspection. This section will discuss the key
aspects of a site inspection that involves both a visual inspec-
tion plus sample collection, the sequence of field activities,
photography, logbook maintenance, and chain-of-custody.
A. Sequence of Field Activities
Almost all site investigations will follow the same sequence of
events. Frequently, the only element that varies is the time
required to perform the event. The following is a list of tasks
in sequential order.
(1) Site Arrival
During this step, the team arrives at the site, notifies the
owner/operator of arrival and sets up the command post and decon-
tamination line/access control points.
(2) Observation/Field Activity
During this stage of the field work the inspectors are:
o making visual observations,
o maintaining a field logbook of observations,
o taking photographs, and
o monitoring for vapor emissions.
(3) Decontamination/Demobilization
At this stage all persons and equipment exiting the site are
decontaminated. This occurs not only at the completion of all
field work but each time persons exit the site, including rest
breaks.
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In many cases, decontamination may be very simple—simply
removing disposable coverals and washing field boots. In other
cases, expecially if sampling is performed, then a more involved
decontamination will be needed. For example, it will probably"
require decontaminating field persons, sample bottles, and sampling
and field equipment.
All clothing and support materials that will not be reused
must be containerized either for transport and eventual disposal
or to leave on the site.
(4) Site Exit
At this stage the team leader should check out with the
owner/operator. If requested, the team leader should provide
the owner/operator with -a receipt describing the photographs
taken.
B. Photography
Photographs collected during the SI should be taken with
regular 35mm cameras. Use of unusual filters should be avoided
as they tend to discolor the picture and may unfairly bias the
result by making leachate seeps or lagoon look worse than real
life. The exact type of camera (including i.d. number), film
(i.e., Fuji, asa 200), and any unusual lenses used must be identi-
fied in the field logbook.
If during the performance of the site inspection, the owner/
operator withdraws his consent for EPA to be on his facility then
any data collected up to that point is admissible data. The
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inspectors may chose after leaving the site to collect visual
information from outsite facility property. If this occurs, then
the data collected must be in plain view from the facility boundary.
Special lenses such as telephoto lens, and binoculars are not
acceptable to use from off-site; regular 35mm cameras are acceptable
Photographs should be taken to document the conditions of
the facility and procedures used in-inspection activities. Two
sets of photographs should be taken in the event one camera does
not function or film processing is poor.
The following identifies the type of pictures that should be
taken:
o representative overall picture(s) of facility,
o posted signs identifying ownership of facility,
o evidence of releases—leachate seeps, pools, discolored
water, or strained soils,
o individual units—lagoons, drums, landfill, etc.,
o-_. visual evidence of poor facility maintenance.
o adjacent land use, and
o area of easy access by unauthorized persons.
C. Logbook Maintenance
The logbook is perhaps the most important document generated
during the site inpection. It will serve as the basis for pre-
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paring the final SI report, interpreting data, describing the
site, and most importantly, defending the work done and results
obtained in any future legal proceedings under RCRA or CERCLA.
A unique logbook should be assigned for each site and each
visit to the site. Logbook should be bound and each page sequen-
tially number. Entries into the logbook should be chronological
—a time notation should introduce each entry. Mistakes in the
logbook should be lined out and initialed. The logbooks should
be maintained with indelible ink.
The following is a list of the types of entries that should
be made in the logbook:
o All personnel on site during each phase of the on site
work;
o All instruments used during the field work with unique
identification numbers;
o Description of film used;
o Description of the weather and changes in the weather;
o Result of field measurements—distances, instrument
readings, well measurements;
o Factual description of structures and features—wells
and well construction, units, containment structures,
buildings, roads, topographic and geomorphic features;
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o Signs of contamination—oily discharges, discolored sur-
faces, dead or stressed vegetation;
o Sketches of facility layout, structured features and
points of contamination,;
o Map of facility showing point and direction of photo-
graphs; and
o Any other relevant items.
For photographic documentation, the following information should
be noted in the logbook.
o The sequence of picture number
o If more than one camera is used, identification of camera
(print or slide)
o person taking picture
o description of picture
Each page of the logbook should be signed by the person
keeping the logbook and counter-signed by a person accompanying
the logbook keeper.
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VIII. SAMPLING INSPECTION
If sample collection is required, it is sometimes possible
to combine the sampling effort with the comprehensive visual
inspection. This would most likely occur where the inspector(s)
has recently visited the site, is thoroughly acquainted with the
facility and is able to identify in advance where samples are to
be taken. If it is not possible to combine the comprehensive
visual inspection with sample collection, the visual inspection
should be geared towards gathering data 'to develop the sampling
plan.
The following is a discussion of activities associated with
a field visit to collect samples.
A. Sequence of Field Activities
In most instances, the sequence of field activities is the
same regardless of whether the purpose is to collect samples.or
conduct comprehensive visual observations.
(1) Site Arrival
This step is the same as previously discussed except that
the inspector should hold a briefing with the EPA field team or
owner/operator team to review the days events and ensure that
each team member understands their responsibilities.
(2) Preliminary Site Entry
The preliminary site entry is the first step of the field
activity. The purpose of the initial site entry is to screen the
facility for situations posing a threat to health, and to support
logistical needs of the site investigations. Preliminary site entry
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will ensure that there have been no changes on site since the
last visit. When a formal site entry is necessary, at least two
team members should walk through the areas of the facility where
work is anticipated with portable instruments to determine if
there are any vapor releases or radiation emissions, if there
is adequate oxygen, or if there are any explosive atmospheres.
the site since the last visit. Depending upon the climate from
one day to the next, the concentration of volatiles, explosive
gases and oxygen can change. Secondly, it is extremely difficult
for field personnel to screen the site while collecting samples,
taking pictures, and maintaining a field log book.
At the end of this step the team leader should evaluate
whether any information -collected during the initial site entry
changes any of the plans. For example, it may be possible to
downgrade the level of protection.
In some cases, it may not be necessary to conduct an initial
site entry if the inspector has had recent contact with the
facility and is confident that the site conditions have not
changed. The site inspector may have adequate, first-hand
information on the facility to insure that the facility poses no
threat to the health of the inspector. Where the inspector has
little data on the facility, or is unsure of the reliability or
completeness of existing data, then an initial site entry to .
screen the site is appropriate.
This step becomes especially important for sampling inspec-
tions. It is extremely difficult to monitor a site with portable
instruments while collecting samples, taking pictures and
maintaining a field log book. If a quick screen is performed
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prior to sampling, then the logistics of field work will be
simplified.
(3) Sample Activity
During this stage of the field work, the following tasks are
occurring:
o collecting samples,
o photographing sample collection,
o maintaining the logbook, and
o monitoring for vapor emissions.
Regardless of who is performing the sample collection,
continuous monitoring for vapor emissions is needed to detect air
releases from sampling activities. If the owner/operator is
collecting the samples, the EPA field team's prime responsibility
is to document precisely the sequence of sampling activities, the
procedures and instruments used, and a description of the samples
(including location, depth, appearance, etc.).
The EPA Regional offices have developed SOP's for most SI
sampling tasks under the CERCLA program. For the most part these
SOP's are applicable to RCRA field activities. If the SOP's are
not applicable or appropriate for the particular field activity
then a new SOP should be developed. In some cases, only minor
modifications are necessary. Were modification to existing SOP's
are made, then the exact modifications must be noted in the field
logbook.
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(4) Decontamination/Demobilization
This stage Is the same for a comprehensive visual SI. In
addition to personnel and equipment decontamination, all samples
must be decontaminated. All sample identification forms, sample
shipping forms, chain-of-custody forms, sample receipts, and
sample traffic forms are completed. Some of the information on
these forms can be filled in prior to the sampling and is in fact
recommended due to the number of forms and time required to
complete these. Examples of each of these forms are contained in
.,
Appendix rr_ All samples are packaged for safe transport. If
samples are to be shipped by express carriers, then the samples
are packaged in accordance with DOT specifications for shipping
of hazardous materials.
(5) Site Exit
This stage is similar to the procedure discussed previously.
In addition, the Inspector should deliver a receipt describing
the samples collected. The inspector should obtain a written
acknowledgement of the receipt of sample form. If the owner/
operator requested split samples, then the samples would be left
with him at this time.
B. Photography
The same principles previously discussed apply to sample
collection tasks. Photographs should be taken of:
o posted signs identifying ownership of facility,
o sampling locations, and
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o sampling activities.
C. Logbook Maintenance
The same principles discussed previously also apply here.
The following is a list of the additional types of entries that
should be made in the logbook for sampling inspections:
o description of sample (appearance),
o exact depth from which sample taken,
o description of location of sample,
o map(s) identifying site layout and sampling points
o field calculations,
o decontamination procedures used between collection of
each sample,
o any deviation from SOPs, and
o any other relevant item.
E. Cnaln-of-Custody
All samples collected (including blanks and spikes) should
be maintained under chain-of-custody. The purpose of chain-of-
custody is to insure that data collected during the SI is not
tampered with before it is analyzed. Chain-of-custody traces the
possession of a sample from the time of collection, through all
transfers of custody, to when it is received in the laboratory,
where internal laboratory chain-of-custody procedures take over.
For samples that are spiked in the laboratory, chain-of-custody
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should be maintained from the time the sample is prepared in the
laboratory to when it is received in the laboratory for analysis.
Specific chain-of-custody procedures are included in the SOP
of chain-of-custody.
IX. SAMPLE SHIPMENT/ANALYSIS OP SAMPLES
At this stage of the SI, any samples that were collected by
the EPA or splits of samples collected by the owner/operator,
are delivered to the laboratory and the samples analyzed. If
the analysis is performed by the EPA Contact Lab Program (CLP)
then most samples will have to be shipped by overnight courrier.
This will involve driving the samples to the closest overnight
courrier office and completing the appropriate sample shipment forms.
Most samples collected at hazardous waste facilities are regulated
by the Dept. of Transportation requlations governing shipping of
hazardous materials. SOP's covering sample shipping are available
in each of the regional offices or in EPA safety training manuals.
The time involved in analyzing samples can vary from 40 days to
three .to four months.
X. ANALYTICAL DATA REVIEW
Upon receipt of analytical results, the data must be reviewed
to insure that the results are valid. This particular step can
take a considerable amount of time depending upon the backlog of
data packages requiring review. The EPA Regional Environmental
Services Divisions (ESDs) are responsible for quality assurance
review of analytical data. In some cases, some or all of the
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responsibility for data review is delegated to the group respons-
ible for collecting the samples.
Some of the data review responsibilities can be delegated to
the persons collecting the samples and do not require involved .
training or experience to perform. Primarily these involve en-
suring that all deliverables required by the CLP are included
in the data package, checking that all forms are completed within
the requirements of the contract, flagging missing data or incom-
plete forms, and reporting these to the appropriate person for
follow-up. Depending upon the arrangements in the particular
Region, the preliminary data review can also involve completing a
checklist of questions which summarize key quality assurance items
in the data package.
With the results provided by this preliminary data review,
missing data will be requested and the ESD's will perform a
qualitative analysis of the data. Based on the abundance of
laboratory internal quality assurance data provided in the data
packages the ESD determines if the data results are valid.
At the completion of the analytical data review, all the
data collected to that point is evaluated to determine if a
release or potential for release has occurred. The substance of
the data evaluation stage is contained in the succeeding chapters.
XI. FINAL REPORT/FILES
After evaluating all the data, a brief report summarizing
the results, findings, and recommendations, should be prepared.
This report should not on average be more than fifteen pages
long. In some cases the report may be longer for a particularly
1-31
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complicated site.
The report should identify the areas or units that are
releasing or suspected to be releasing and the basis for these
findings. The report should also recommend, area (or units)
where no further action, immediate interim corrective action, or
remedial investigation is required. The basis for these
recommendations should be clearly substantiated in the report.
The relative priority of the facility for follow up investigation
should be explained. In addition, where further action is recommended,
the report should also describe the scope of further action.
The following is a recommended outline for a SI report. It
may not be necessary to discuss all the items identified in the
outline if the discussion is clearly irrelevant to the particular
site. For example, it may not be necessary to elaborate on the
geology or hydrology of an area if the only unit of concern is an
inactive above ground storage facility with no problem spill,
discharge or overflow problems.
9 Site Background
This section should summarize, among other things, the loca-
tion of the facility, the types of hazardous waste handling
practices (by unit), which units are regulated, the layout of the
facility (include a map), how long the facility and units have
been in operation, and the site ownership. This section is not
intended to repeat detailed data already provided in the Part B
application or CERCLA SI report. The report should briefly summarize
data found in other documets, and describe new data identified.
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o Environmental Setting
This section should describe, in summary form, the media
surrounding the facility—the relevant climatic, geological,
hydrogeological, and topographical factors. Maps, sketches, and
selected photographs would be included in this section to further
describe the physical environment. Also included in this section
would be a discussion of target populations and environments—
including public and private water supply ground and surface
water intakes, protected areas, parks, wetlands, affected irrigated
crops and livestock.
o Unit/Waste Description
This section would discuss the types of units found at the
facility and their tendency to cause releases into the air,
ground water, surface water, soil and subsurface gas. This
section would discuss the relevant design and operational features
that exist or do not exist to adequately contain hazardous wastes
or releases of hazardous wastes. This discussion would also
include situations where it is unknown what type of design or
operational features existed to control or contain hazardous
waste. As part of this-discussion, the types of wastes handled
by each unit would be described.
o Laboratory Results
This section would discuss the results of previous and new
analytical results. Much of the information in this section
would be presented in tabular form and would be accompanied with
maps locating sample collection points.
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o lexicological Characteristics
This section would discuss toxicological characteristics of
the wastes releasing or suspected to be releasing into the envi-
ronment. The report would focus only on the most toxic and
persistent chemicals releasing.
o Conclusions and Recommendations
This section would present the findings and conclusions from
those findings. Documented releases should be discussed in .
this section as well as findings that releases are soon or likely
to occur. Areas where insufficient data document a release
should be discussed. Units that are found not to be releasing
should be identified and discussed. Recommendations for further
action on units not eliminated from further consideration should
be presented. Where the facility or some portion of the facility
is recommended for an RI or corrective action, brief and generalized
discussion of the scope of further work should be included.
Recommendation for deferral of further action should also be
explained in this section.
o Bibliography
This section would Identify all sources of information used
in the evaluation and preparation of the SI report. This portion
would be essential if the facility is referred to the CERCLA
program for consideration for the National Priorities List (NPL).
o Appendices
Any relevant memorandum, reports, pages from reports, maps,
etc. that elaborate upon or further substantiate information in
1-34
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the SI report would be attached In this section.
A copy of the final report plus all memoranda, photographs,
logbooks, trip reports, workplans, sampling plans, safety plans,
sample tags, chain-of-custody forms, records of communication,
plus any new reports or documents uncovered in the course of
conducting the SI, should be entered into the official facility
file. All this information will be used as evidentiary documentation
In any future court proceedings.
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CHAPTER FIVE
' SURFACE WATER
I. INTRODUCTION
The site investlgation • for surface water should determine
whether solid waste management units at the facility have released
and/or will continue to release hazardous wastes or hazardous
constituents to surface water.1 For units with identified releases,
or for which there is a substantial likelihood of a release, the
owner or operator will be required to conduct further investigations
to actually determine the extent of a release(s) and/or to charac-
terize the release and begin developing a corrective measures
p rogram.
Although EPA is primarily concerned with releases to surface
water, such releases can also migrate overlaod and potentially
expose human and environmental receptors. Releases to surface
water and off-site may result from point source discharges,
spills, leaks, surface run-off, or floods.
The investigator will need to make determinations regarding
the need for further lovestigation at a unit on a case-by-case
basis, considering factors that are unique to each unit. For
some units, it may be relatively easy to assess the potential for
surface water contamination and to determine the need to conduct
further investigations. For other units, it may be more difficult
to make these determinations and the investigator will need to
use judgment in deciding whether farther investigations are
warran ted.
1 Surface water includes any stream, river, lake, bay,
wetland, estuary, and intermittent stream.
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Releases that result la surface water or off-site contamina-
tion can be difficult to identify because of their intermittent
nature. For example, a surface impoundment may regularly overflow
and release hazardous constituents during periods of heavy rain-
fall. However, unless the site investigation is conducted during
a heavy rainfall, the investigator will not observe the release.
Therefore, he/she should evaluate each unit at the facility for
its potential to cause surface water releases and examine the
site for evidence that indicates such releases have occurred or
occur on a regular basis. The investigator will also need to
assess whether such releases threaten human health and the envi-
ronment before determining that further investigations are
necessary.
The comprehensive investigations called for in the second
phase of the corrective action process require a considerable
investaent of time and resources for both the owner or operator
in conducting the investigation, and for the agency in reviewing
technical plans and analytical results. Therefore, the PA/SI
should serve the dual function of identifying situations which
me r 11-_ f ur ther investigations for surface water releases, and at
the same time avoiding unnecessary investigations.
This chapter describes tha factors the investigator should
consider in assessing specific units and the site for their
potential to cause releases to surface water. It also describes
the kinds of evidence the investigator should look for to identify
whether or not a release has taken place and fictors to consider
in assessing the potential for releases to threaten human health
and the environment.
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II. POTENTIAL FOR SURFACE WATER RELEASES FROM THE FACILITY
Four factors are important in assessing the potential for
surface water contamination from a facility. They are:
o the proximity of 'the facility to surface water;
o the potential for releases to migrate from the
facility to surface water or directly to off-site
receptors;
o the design and physical condition of solid waste manage-
ment units at the facility; and
o the type of wastes contained in these units.
The importance of each of these factors is discussed below.
Proximity to Surface Water and Release Migration Potential
The potential for surface water contamination from a facility
is directly related to the facility's proximity to surface water.
Facilities located along rivers or other surface water bodies are
more likely to have surface water releases than facilities located
in arid areas, far from significant surface water bodies. As the
distance to surface water increases, it becomes more likely that
hazardous constituents in surface run-off will sorb to soils or
move downward in the unsaturated zone and result in ground water
con tami na tion.
The potential for surface run-off from the facility to
migrate overland to nearby receptors is only of concern when the
facility is located adjacent to populated areas and no barrier
(e.g., runoff control system) exists to prevent further overland
migration.
Proximity is not the only factor that affects the potential
for releases to migrate to surface water or drain off-site. The
facility slope indicates the potential for run-off or spills to
5-3
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migrate from the facility. For example, releases from a facility
located in a depressed area are unlikely to leave the site as
surface run-off. The composition of the soil and the slope and
vegetation of the terrain between the facility and the nearest
surface water body will also affect the migration potential of.
the release. For example, a facility located close to surface
water may have a low potential for surface water releases if the
intervening terrain is characterized by sandy soils and heavy
vegetation. In this case, run-off is more likely to migrate down
into the unsaturated and saturated zones rather than to migrate
laterally overland to surface water. However, fac 11ities located
in areas characterized by clayey soil, and where there is less
extensive vegetation between the site and nearby surface water,
have a greater potential for releases to surface water.
The level of rainfall and the frequency of significant storm
events also affect the potential for run-off from the facility to
contaminate surface water. As mentioned earlier in this chapter,
surface water releases are often intermittent and result from run-
off generated during periods of heavy rainfall. A facility lo-
cated in an area characterized by frequent major storm events is
more likely to generate large volumes of surface run-off than a
facility located in an area where major storm events are less
f req uent.
The assimilative capacity of the closest surface water body
also affects the migration potential of releases from a facility.
Large streams with high flow rates will tend to degrade or mix
and dilute constituents mora rapidly than smaller streams with
lower flow rates.
5-4
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The investigator will need to consider all of these factors
— proximity to surface water, soil composition, slope and
vegetation characteristics of the facility and the intervening
terrain, assimilative capacity of nearby streams, rainfall, and
the frequency of major storm events -- to determine how the
facility's location affects the potential for releases to surface
water or the movement of surface run-off to off-site receptors.
Untt Design and Physical Condition
As with the other media, the potential for surface water contam-
ination from a solid waste management unit is largely dependent
on the nature and function of the unit. For example, open units
that contain liquids (e.g., surface impoundments) have a greater
potential for surface water releases than closed landfill cells
that have been properly capped.
Table 5-1 ranks types of solid waste management units, in
a loose descending order on the basis of their potential for
having releases that cause surface water contamination or migrate
off-site as surface run-off. The table is intended to provide
a general sense of the relative potential for units to cause
thesei.types of releases. The investigator will also need to
evaluate unit-specific factors in determining the potential for
surface water releases from a particular unit.
The major unit-specific factors the investigator should
evaluate include:
o uni t design. The investigator should determine whether
the unit has engineered features (e.g., run-off control
systems) that are designed to prevent releases to surface
water. If such features are in place, the investigator
should evaluate whether they are adequate (in terms of
capacity, engineering, etc.) to prevent releases.
5-5
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Table 5-
Unit Type
Landfill
Surface Impoundment
Waste Pile
Container Storage Area
1. UNIT POTENTIAL FOR SURFACE WATER
RELEASES AND MECHANISMS OF RELEASE
Release Mechanism
o Migration of run-off outside the unit's
run-off collection and containment system
o Migration of spills and other releases
outside the containment area from loading
and unloading operations
o Releases from overtopping
o Seepage through dikes to surrounding
areas (i.e., soils, pavement, etc.)
o Migration of run-off outside the unit's
run-off collection and containment system
o Migration of spills and other releases
outside the containment area from loading
and unloading operations
o Migration of run-off outside the con-
tainment area
Land Treatment Unit
Above-ground Tank
In-ground Tank
Inc inera tor
Class I and V
Injection Well
o Migration of run-off outside the con-
tainment area
o Releases from overflow
o Leaks through tank shell
o Spills from coupling/uncoupling opera-
tions
o Releases from overflow
o Spills from coupling/uncoupi ing opera-
tions
o Spills or other releases from waste
handling/preparation activities
o Spills due to mechanical failure
o Spills from waste handling operations
at the well head
* The two remaining solid waste management units; waste transfer
stations, and waste recycling operations generally have mechanisms
of release similar to tanks.
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making these determinations. To the extent waste information is
available, the investigator may be able to take these factors
into account. Each factor is discussed more fully below.
1. Mas s. The mass of a contaminant relative to the volume
of the receiving water body is one of the primary factors governing
the environmental significance of a release. The high volumes of
water present in some rivers and lakes will dilute many contam-
inants so that concentrations are below levels that impact human
health or the environment. Volume and flow rate govern the
ability of a water body to assimilate a contaminant. Larger
bodies of water can assimilate higher quantities of pollutants
than smaller ones, and more turbulent streams and rivers expedite
the mixing and dilution process and assimilate pollutants more
quickly than slow moving or stagnant bodies of water.
2. Transport Mechanisms. The transport mechanisms governing
the movement of pollutants control their ultimate destination.
The primary transport mechanisms are sedimentation, volatilization,
and downstream transport in the water column. The strucutre and
properties of each constituent will govern which mechanisms
dominate their transport. While most constituents can be affscte'd
by all three transport mechanisms, it is possible in most cases
to partition a constituent to one primary destination. This
information can be used to predict where specific constituents
will result in potential exposures. A brief description of each
fate and transport mechanism follows:
o sedimentation. Sed linen ta t ion refers to the tendency of a
constituent to sorb onto suspended organic sediments
carried in water bodies. Sorption can be modeled using a
sorption isotherm, which predicts the relative tendency
of a constituent to be partitioned to suspended particles
5-8
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or to remain dissolved in the water. The sorption parti-
tion coefficient, KSW, describes the tendency of a con-
stituent to be dissolved in the water phase or to be
sorbed onto a particle. Once a constituent has become
sorbed to a particle in the water, it will usually join
the bottom sediments of the system.
o vola tilization. Compounds exhibiting a strong tendency
to volatilize from water will pose little risk to human
health or the environment through surface water exposures.
Many chlorinated solvents will almost completely vola-
tilize from a moving stream within several miles. Com-
pounds with large Henry's Law constants will have the
greatest potential for volatilization. It will be ac-
centuated in turbulent water systems such as fast moving
streams, where the turbulence speeds up the transfer of
contaminants from water to air.
o downstream transport. Relatively immiscible organic
compounds with densities less than water (e.g., oily
wastes) will tend to float on water surfaces in slicks,
where they may pose a significant threat to water fowl.
Other immiscible compounds which are heavier than water
will tend to sink into the sediments where they will
remain largely undlssolved in the water column. Dissolved
constituents will be transported downstream in rivers and
dispersed in lakes where they will be subject to natural
fa te processe s.
3. Pers is tence. Many fate processes can combine to degrade
a pollutant to a level below which there is no significant risk.
Among the many fate processes are: hydrolysis, photolysis, oxida-
tion/reduction, biotrans formation, and bioaccumulation. Many
references will report a value for a chemical's half-life in
water""based upon a combination of these processes. In this way,
one can make a general assessment of a constituent's persistence
in the environment. The most persistent constituents (e.g., PCBs,
dioxins, etc.) will not be significantly degraded by any of the
fate processes mentioned above and should generally be considered
to pose a considerable risk. Bioaccumulation deserves special
mention due to the unusual threat it poses to animals in the food
chain. Concentrations of constituents that bioaccumulate in fish
and shellfish may be higher in the fish than they were in the
5-9
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original release. Pollutants that bioaccumulate should be given
special consideration in water bodies used for recreational or
commercial fishing.
4. Toxicity. The most pertinent factor in assessing the
significance of a release of hazardous constituents to surface
water will often be the intrinsic toxicity of each individual
contaminant. Large releases of certain non-carcinogens may be
assimilated in streams or lakes without consequence to human
health or the environment. However, low concentrations of highly
toxic and/or persistent constituents like dtoxin, PCBs, arsenic,
and cyanides may pose a significant human health risk. Unfor-
tunately, toxicity information for many of the Appendix VIII
constituents is incomplete. For this reason, it will often be
advisable to consider highly persistent constituents to be of the
greatest concern, because exposures can occur over a considerable
length of time with unknown consequences.
While the overall fate and transport of a constituent in a
surface water system will depend on the specific characteristics
of the system, it is possible to generally describe the likely
fate and transport for certain classes of contaminants. If the
investigator knows the wastes in the unit, this information may
help in determining which contaminants are of particular concern
for surface water releases.
o metals (e.g., arsenic, chromium, cyanide, and mercury)
usually adsorb and accumulate in sediments in rivers and
lakes. The rate at which they concentrate in the sediments
will depend on the organic content of the suspended
solids in the system and on the concentration of clays in
the water. Most metals will exhibit a tendency to bio-
accumulate in both shellfish and finfish. They will
therefore pose the greatest threat to human health in
waters known to be used for recreational and commerical
fishing.
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o chlorinated pesticides (e.g., DDT, chlordane, lindane,
heptachlor, toxaphene, etc.) may be subject to several
fate and transport processes simultaneously. They have
been shown to volatilize, sorb onto sediments, biodegrade,
and bioaccumulate. In large quantities, chlorinated
pesticides mmay pose a significant risk from exposure
throughout the water body.
o halogenated alipha tic hydrocarbons (e.g., trichlorethane,
tetrachlorethene , chloromethane, etc.) generally exhibit
a strong tendency to volatilize from water. Large quan-
tities of these pollutants can be stripped from fast-moving,
turbulent streams, reducing their risk for water-associated
exposures. Although they will not tend to be transported
downstream, they generally do not degrade significantly
in the environment. Many of these compounds may still
pose a significant risk at low concentrations due to
. their toxicity.
o polycyclic aromatic hydrocarbons (e.g., napthalene,
phenanthrene, benzo(a) pyrene, etc.) will tend to adsorb
to bottom sediments. These pollutants are generally
susceptible to biodegration and hydrolysis in surface
water systems. Because they do not tend to bioaccumulate,
releases characterized by low concentrations of these
pollutants are likely to be of little concern.
Summary of Factors Affee ting the Potential for Release
The investigator should consider all of the factors described
above to determine a unit's surface water release potential. In
addition, in assessing a unit's potential for surface water
releases, the investigator should consider how the various factors
affec'-L each other. For example, an above ground tank containing
relatively toxic, persistent waste and located within 1000 feet
of a river may not have a secondary containment or other system
in place to collect liquid waste that could leak or overflow
from the tank. However, the facility's records indicate that the
tank is relatively new, well designed, and well constructed, and
that it is inspected regularly for evidence of leaks. In this
case, there is only a low potential for a release to surface
water, and no further investigation would be necessary.
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Alternatively, the same situation with an older tank that shows
signs of deterioration may require further investigation.
III. EVIDENCE OF SURFACE WATER RELEASES
If the investigator determines that certain units at the
facility have the potential to cause releases to surface water,
he/she should inspect the area around the units of concern and
the area between the unit and the closest surface water body for
evidence of a release. In addition, if the facility is located
adjacent to surface water, the investigator should examine the
surface water for evidence of releases. The investigator should
look for the following types of evidence:
o unpermitted discharges to surface water that require
NPDES or Section 404 permits. Hazardous waste facilities
may be using certain practices that require permits under
the Clean Water Act. The investigator should examine the
site for the following types of discharges and determine
whether these discharges are permitted:
-- discharges from collection and holding facilities
(e.g., tanks, basins, surface impoundments, etc.);
-- discharges of contaminated ground water from a
counterpumping activity;
— discharges from a leachate collec tion/trea taien t system;
-- placement of dredge or fill material in the water; and
— units (including old fill material that is now consi-
dered hazardous waste) in surface water.
o visible evidence of uncontrolled run-off from units at
the facility. If releases have occurred or are occurring
at a unit there, is likely to be evidence around the unit
that indicates a release is taking place. Because of the
intermittent nature of most surface water releases, it
is particularly important to examine the site and nearby
surface water for physical evidence of release. The
investigator should look for:
— observable contaminated run-off or leachate seeps;
-- drainage patterns that indicate possible run-off from
units at the facility;
— evidence of wash-outs or floods, such as highly eroded
soil, damaged trees, etc.;
-- discolored soil, standing water, or dead vegetation
along drainage patterns leading from the unit; and
— discolored surface water, sediment or dead aquatic
vege ta t ion.
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Use of Sampling to Support Other Evidence Obtained
Depending on the other evidence collected, it may be desire-
able to sample run-off, on-site soils, standing water, surface
water, and/or surface water sediments. While the Agency expects
that in general, it will not be necessary to take samples duri-ng
the PA/SI, there may be certain situations where sampling can
confirm other evidence that a release has taken place at a unit
or that there is no release from a unit. Sampling should only be
conducted to verify or confirm other evidence collected.
For example, inspection of units and the facility may indi-
cate the potential for surface water releases (e.g., tanks at the
facility are older and inadequately designed; many have contained
toxic wastes for more than 20 years; and the facility is located
adjacent to a relatively small stream). While there is ao visible
evidence of leaks or fractures in the tanks, other evidence
indicates that surface water releases are taking place (e.g.,
run-off in drainage channels leading from the units is discolored,
and there is dead vegetation along the drainage channels). In
this case, the investigator may want to sample run-off in the
chann-els for indications of contamination.
In general, simple field tests or sampling may be adequate
to obtain a positive confirmation of surface water or surface
run-off contamination. More thorough sampling may be necessary
to conflm that the contamination results from a particular unit,
but this more detailed sampling may be completed as part of the
next phase of the corrective action process. If the investigator
determines that sampling is necessary, he/she should follow the
procedures that are provided in Appendix . Procedures for
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analyzing samples for hazardous constituents described in 40 CFR
Part 261, Subparts C and D, can be found in "Test Methods for
Evaluating Solid Waste, Physical/Chemical Methods (SW-846)."
IV. EXPOSURE POTENTIAL
If the investigator observes discharges or releases to
surface water or other evidence that such releases are taking
place, he/she may choose to use exposure information (to the
extent it is available for the facility) to: 1) determine the
need for further investigations; and/or 2) set priorities for
conducting further investigations.
The following types of information are useful in evaluating
the exposure potential of surface water releases:
o information on the use of the surface water body that
receives the release. The investigator should determine
the use of the surface water body (e.g., no use, commer-
cial or industrial, irrigation, economically important
resource (e.g., shellfish, commercial food preparation,
recreation, or drinking). A release is more likely to
significantly impact surface water that is used as a
drinking water source than surface water in industrial
areas that have a commercial or industrial use.
o information on the location of any drinking or irrigation
water intakes listed in public records or otherwise known
within a reasonable distance of the release.
o Information on the nature and extent of the contact human
and environmental receptors are likely to have with run-
off from the facility.
V. SUMMARY AND EXAMPLES
This chapter has identified certain unit-specific and site-
specific characteristics that should be evaluated to determine
the potential for surface water releases or releases that migrate
off-site in surface run-off. These characteristics include: the
proximity of the facility to surface water; factors such as soil
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type, slope, and vegetation of the intervening terrain that
affect the migration potential of a release; the design and physi-
cal condition of solid waste management units at the facility;
and the type of waste contained in the solid waste management
units. The Investigator should examine each of these factors and
how they relate to each other in determining the potential for
surface water releases from units at the facility.
Once the investigator determines that the potential for
surface water releases exists at a facility, he/she should examine
areas surrounding the units of concern and the site as a whole
for evidence that releases have occurred or are occurring at a
facility. Due to the intermittent nature of most surface water
releases, it is important to look for physical evidence such as
drainage patterns, dead vegetation, etc., that Indicates that
releases have taken place. The investigator should also consider
the potential for exposure from these releases before making a
determination that further investigation is necessary.
Table 5-2 provides examples of situations that are likely
to require further investigation and situations that probably
will trot require further investigation.
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Table 5-2
UNIT ILLUSTRATIONS
nit Type
Landfills
Vaste Piles
Surface
Impoundmen ts
Container
S torage
Areas
Land Treat-
men t Units
Further Investigation
Needed
Closed units, inadequate
or deteriorating cover,
no run-off control system;
drainage patterns indicate
contaminant migration (i.e.,
discolored soil and/or dead
vegetation); near downgrad-
ient surface water/off-site
receptors
Closed units, waste inade-
quately covered, no run-off
control system; drainage
patterns indicate migration
of contaminants; near sur-
face water
Operating/closed units with
inadequate freeboard or
deteriorating dikes; located
adjacent to stream that has
downstream drinking water
in take s
Operating/closed units with
deteriorating dikes; evidence
of release; near surface
wa te r
Inactive units with leaking
containers; visible evidence
of soil contamination; no
run-off control system,
drainage channels indicate
migration of hazardous
constituents
Inactive/operating units
with visible evidence of
soil contamination; unit
design allows run-off; near
downgradient surface water
and/or off-site receptors
Further Investigation
Not Needed
Operating units with
adequate run-off
control systems
Closed units with adequate
caps or covers; no evidence
of run-off from the unit
Operating units with run-
off control systems
Closed units with adequate
caps or covers; no evidence
of run-off from the unit
Older operating/closed
units with adequate freeboard
and overtopping controls;
limited potential for off-
site exposure; more than 3
miles from nearest surface
wa ter
Operating units with new,
well sealed containers; or
adequate run-off controls
Inactive units with well
sealed containers; ade-
quate run-off controls;
limited potential for off-
site exposure, no nearby
downgradient surface water
Inactive/operating units
with adequate run-off
controls; limited potential
for off-site exposure
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Table 5-2 (Continued)
UNIT ILLUSTRATIONS
IP it Type
Tanks
Incin-
era tors
Class I/
IV Inject-
ion Wells
Further Investigation
Needed
Older concrete units with
no secondary containment,
some visible deterioration;
visible evidence suggests
some overland migration of
hazardous constituents;
near surface water
Unit with visible evidence
of soil contamination
from apparent (or recorded)
overflow events or other
operational or structural
failures; unit in area with
clayey soil, near surface
wa ter
Evidence of recurring spills
that result from waste
handling operations;
drainage channels leading
from the unit indicate
contaminant migration;
near surface water
Evidence of recurring spills
that result from waste
handling operations; drainage
channels leading from the
unit indicate contaminant
migration; near surface water
Further Investigation
Not Needed
Well-designed, construc-
ted units; inspected
regularly; no evidence
of leaks
Older units that shown
signs of deterioration;
no potential for off-
site migration of con-
s tituents
Design ensures containment
of spills that could occur
during waste handling
opera tions
Design ensures containment
of spills that could occur
during waste handling
opera tions
5-17
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CHAPTER SIX
AIR
I. INTRODUCTION
The site Investigation for air should determine whether solid
waste management units at the facility have released or are
likely to have released hazardous wastes or constituents to the
air. Owners or operators of units with identified releases or
that have a substantial likelihood of a release will be required
to conduct further investigations to actually determine the
extent of a release(s) and/or to characterize the release and
begin developing a corrective measures program.
In general, two types of air releases can occur at solid
waste management units:
o releases that are continuous in nature, and
o releases that are intermittent or catastrophic In nature.
This guidance is primarily concerned with evaluating the likelihood
and significance of continuous releases. It is assumed that all
units that expose hazardous waste to the ambient atmosphere have
air releases; the investigator will need to use judgment in
determining whether these releases are significant enough to
warrant further investigation. For some units it may be relatively
easy to make these determinations; for other units, these deter-
minations may be more difficult.
Because the comprehensive investigations called for in the
second phase of the corrective action process require a considerable
investment of time and resources for both the owner or operator
and for the agency, the PA/SI should serve the dual role of
identifying situations which merit further investigations for air
-------
releases while at the same time avoiding unnecessary investigations.
This chapter describes the factors the investigator should
consider in evaluating specific units and the facility as a whole
for their potential to cause air releases. It then describes the
kinds of evidence the investigator should look for to determine
that a release has taken place and factors to consider in asses-
sing the potential for releases to threaten human health and the
environmen t.
II. POTENTIAL FOR AIR RELEASES FROM THE FACILITY
Three factors are important in assessing the potential for
significant air releases from a facility. They are:
o unit characteristics, such as size, type and use;
o types of wastes/constituents in the unit; and
o potential for mitigating exposure resulting from the release
This section describes each of these factors in greater detail.
Unit Characteris ti^cs tha t Af f ec t the go ten tial f or Air Releases
When conducting the site investigation for air, Agency
personnel should assess both RCRA-regulated and non-RCRA units
and should focus the investigation on operating units. Operating
units have the greatest potential for air releases because they
actively expose wastes to the air on a continuous basis. Wastes
in closed, inactive units are usually covered. There may be some
exposure to the air if a cover has eroded or broken down, but air
releases resulting from these situations are likely to be
insignificant.
When assessing the potential for releases, the key factors
to examine include:
6-2
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unit size. The size of a unit determines the mass of
potential contaminants available for release. In addi-
tion, volatilization rates are likely to be larger from
open units (e.g., surface impoundments and open tanks)
with large surface areas and shallow depths.
0 purpose of the unit (treatment, storage, or disposal).
In general, units in which active treatment is occurring
have the greatest potential for air releases. In many
cases, treatment is designed to promote volatilization of
constituents. In other cases, this is not the main
purpose of the treatment method in use. However, the
resultant mixing and movement of wastes leads to high
volatilization rates.
o design of the unit. Units in which wastes are in direct
Contact with the a tmosphere have a higher potential for
releases than closed or covered units.
o current operational status. The nature of air releases
is such that the majority of the mass available for
release will be released shortly after the waste is
placed in the unit. Thus, as mentioned, operating units
are of greater concern than closed units. This is par-
ticularly true for unit types and wastes for which vola-
tilization is important. Units with potential particulate
releases may continue to release contaminants well after
closure, especially if the unit has been poorly maintained.
o unit specific factors. There are specific design and oper-
ational factors associated with each unit type which are
useful in evaluating the possible magnitude of a potential
release. These factors are summarized in Table 6-1.
In addition to considering the individual unit sizes, the
investigator should be aware of the to tal area used for solid
waste.management at a facility. Although individual units may
have small releases, the total release from a facility can be
significant. Table 6-1 lists specific considerations for
particularly important unit types.
In assessing a unit's potential for air release, the inves-
tigator should be aware of the importance of interactions between
the various unit characteristics listed above and the characteris-
tics of the wastes placed in the unit. It is important to
examine how these two factors combine to result in an air release.
6-3
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Table 6-1
UNIT POTENTIAL FOR AIR RELEASES
AND MECHANISMS OF RELEASE
Unit Type
Operating Surface
Impound men ts
Open Roofed Tanks
Landfills
Land Treatment Units
Waste Piles
Characteristics and Mechanising of Release
o Wastes directly exposed to atmosphere
promotes vapor phase emissions
o Large surface areas and shallow depths
promote increased volatilization
o Mechanical treatment methods (such as
aeration) increase volatilization
o Wastes directly exposed to atmosphere
(promotes vapor 'phase emissions)
o Mechanical treatment or frequent mixing
will increase volatilization
o Volatilization of vapor phase constituents
through the sub-surface and da ily / perrnanen t
cover
o Poor or no daily cover increases volatili-
zation
o Open trench fill operations allow direct
exposure of waste to atmosphere
o Volatile gases transported by convection
of biogenic gases released via routine
landfill venting (particularly important
in sanitary/hazardous mixed fills)
o Particulate releases generated by machinery
during filling operations
o Particulate releases due to wind erosion of
cover and/or exposed wastes
o Wastes normally in direct contact with
atmosphere
o Application techniques which maximize waste
contact with atmosphere, such as surface
spreading or spray irrigation promote
increased volatilization
o Particulate releases due to wind erosion
o Particulate emissions from uncovered
waste piles
o Location of waste pile in open area with
no erosion protection promotes particulate
genera tion
o Waste handling activities on and arounci
pile increase emissions
o Volatile emissions are likely to be rare,
but can occur based on waste composition
6-4
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Table 6-1 continued
Unit type Characteristics and Mechanisims of Release
Drum Storage Areas o Vaporization from drums frequently left
open to atmosphere or from poorly sealed
drums.
o Vapor emissions from areas containing leaking
drums
Covered Tanks o Volatile releases from pressure venting,
poorly sealed access ports, or improperly
operated and maintained valves and seals.
Incinerators o Stack emissions of particulates
o Stack emissions of volatile constituents.
High temperatures may cause volatilization
of low vapor pressure organics and metals.
o Volatile releases via malfunctioning valves
during incinerator charging
Non-RCRA Wastewater o Low concentration wastes may volatilize
Treatment Ponds and due to large surface area and active waste
Tanks treatment. Releases can be significat
releases due to generally large treatment
capaci ties
Other Design and o Inadequate spill collection systems promote
Operating Practices intermittent air releases
o Lack of vapor collection systems for use
during container/tank cleaning operations
o Absence of dust suppression or particulate
control measures
6-5
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For example, a facility may have several large operating surface
impoundments, suggesting a potential for large air releases.
However, if the facility is a steel manufacturer treating only
spent pickle liquor in these ponds, it is unlikely any air
release will occur because the hazardous constituents in the
waste are non-volatile, soluble metals.
The following section discusses the waste and constituent-
specific factors the investigator should consider in assessing a
waste's potential to release airborne constituents.
Types of Waste Contained in the Unit
Only certain hazardous constituents have a significant
potential for air releases. This section identifies these con-
stituents and the factors that affect the magnitude of their
release.
Volatile constituents of concern for air releases include
organic vapors and volatile metals (e.g., arsenic and mercury).
Table 6-2 lists a select number of hazardous chemical compounds
which EPA's Office of Air Quality Planning and Standards (OAQPS)
considers to be of prime concern with respect to vapor phase air
releas'es. The table also lists the RCRA waste codes for waste
streams that contain these constituents to aid in their
identifica tion.
Table 6-3 lists hazardous constituents that are of special
concern for particulate air releases. Particulate emissions from
solid waste management units can contain organic material, heavy
metals, or both. The heavy metals shown in Table 6-2 are
predominantly associated with particulate releases, although
6-6
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Table 6-2
HAZARDOUS CONSTITUENTS OF CONCERN AS VAPOR RELEASES
Hazardous Constituent
Ace taldehyde
Ac role in
Acrylon i trlie
Allylchloride
Benzene
Be nzyl chloride
Carbon Tetrachloride
Chlorobenz eae
Chloro fo rm
Chloroprene
Cresols
Cumene (isopropylbenzene)
1,4-dichlorobenzene
1,2-dichloroethane
Dlchlorome thane
Dioxin
Ep ichlorohydrin
E thylbe nzene
Ethylene oxide
Fo rmaIdehyde
Hexachlorobu tadiene
Hexachlorocyclopentadiene
RCRA Waste Codes
K001 ,U001
K012
K011 .K012.K013,0009
F024.F025
F024.F025 ,K001 , KOI 4,KOI 9,K083,K085,K103,K105
K015,K085,P028
F001,F024,F025,K016,K016,K020,K021,K073,U211
F001,F002,F024,F025,K015,K016,K085,K105
F002,F024,F025,K009,K010 ,K016 ,K019,K020,
£G73,K02l,K029,U044
F024.F025
F004.U052
U055
F002,F024,F025,K016,K085,K105,U072
KOI 8,KOI 9,K020,K029,K030,K096,F024,F025,U077
F001,F002,F024,F025,K009,K010,K021,U080
F020,F021,F022,F023,F023
K017,KO19,K020,U041
F003
Ul 15
K009,KOIO,K038,K040,U122
F024,F025,K040,K016,K018,K030,U128
F024, F025 ,K032 ,K033 ,'<034 /J130
6-7
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Table 6-2 (Continued)
HAZARDOUS CONSTITUENTS OF CONCERN AS VAPOR RELEASES
Hazardous Constituent
Hydrogen cyanide
Hydrogen flouride
Hydrogen sulfide
Maleic anhydride
Methyl acetate
N-Dlme thylni trosacnine
Naph thalene
Ni tr obenz ene
Nitrosoraorpholine
Phenol
Pho sgene
Phthalic anhydride
olychlorina ted biphenyls
Aroclor 1242
Aroclor 1248
Aroclor 1254
Aroclor 1260
Propylene oxide
1 , 1,2,2-te-jrrachloroethane
Tetrachloroethylene
Toluene
1 , 1 , 1-trichloroethane
Trichloroethylene
Vinylchloride
Vinylidenechlorida
yl enes
RCRA Waste Codes
F007,F009,FOIO,K013,K060
K023,K093,U147
U100
F024,F025,K001,K035,K060,K087,U165
F004,K025,K083,K103,U169
K001,K022,K087,U188
P095
K016,K023,K024,K093,K094,U190
K085
F024,F025,K016,K019,K020,K021,K030,K095,
K096.U209
F001,F002,F024,F025,K016,K018,K109,K020,
K021 ,U210
F005,F024,F025,K015,K036,K037,U220
F001,F002,F024,F025,K019,K020,K023,K029,
K073,K095,K096,(J226
F001,F002,rC24,F025,K016,K018,K019,K020,'J22S
K019,K020,K023,K029,K:028,F024,F025,U043
F003,F025,K019 ,K020,?024,K029,U078
F020.U239
6-8
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Table 6-3
HAZARDOUS CONSTITUENTS OF
CONCERN AS PARTICULATE RELEASES
Hazardous Constituent
Arsenic
Asbes tos
Be ry 11 i um
Cad mium
Chrorai um
Lead
Mercury
Nickle
RCRA Waste Codes
DOOO,D004,K060,K021,K084,P010,
P011 ,P012
U013
DOOO,D006,P015
DO00,0006,F006,F007,F008,F009,
F061,F062, F064,F065,F067,F068,F069
DOOO.D007,F006,F007,F003,F009,F002,
F064,F069,F086,
DOOO,D008,?006,F009,K003.K044.K048,
K052,K061,K062,K064,K069 KO86, PI 10
D008.K071,K106
F006,F007,F008,F009
6-9
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both arsenic and mercury may be present as vapor phase releases
due to their relatively high vapor pressures. Similarly, the
organic compounds shown in Table 6-2 may also be found adsorbed
or bound to soil and/or other particulate matter releases.
The investigator should examine all available information on
wastes handled at the facility to determine the presence of any
of the wastes or constituents referenced above.
Waste Characteristics that Affect the Magnitude of Release
The physical form of the waste contained in a solid waste
management unit will determine to a great extent the potential
for air releases from the unit. Wastes may be solid, dilute
aqueous solutions, dilute organic solutions, or concentrated
solutions. Air releases from solid wastes, such as those placed
in landfills or waste piles, will be governed by different
principles than govern releases from liquid wastes. Liquid
wastes will exhibit potentials for air release that depend upon
the strength of the solution and the type of solvent (e.g., water
or organic compounds such as oil or chlorinated solvents) in the
unit.
The concentration of specific constituents in each unit is
another factor governing the potential magnitude of air releases.
The higher the concentration of a particular constituent present
in a unit, the greater is its potential for significant air
release. However, the intrinsic potential for a constituent to
volatilize depends on chemical and physical properties that very
greatly between different constituents. Accordingly, a highly
concentrated solution of one constituent aiay result in a lower re-
lease potential than a dilute concentration of another constituent.
6-10
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As indicated earlier, the two types of emissions of greatest
concern are volatiles and particulates. Each type of emission
has its own set of characteristics which can help the Investigator
assess the potential magnitude of a release. These characteris-
tics are discussed below and summarized in Table 6-4, which
outlines the likely unit types and appropriate parameters to
consider when evaluating airborne releases from different types
of waste streams.
Volatile emissions. Constituent-specific physical and
chemical parameters are very Important indicators of the potential
magnitude of a vapor-phase release. In some situations, these
parameters can be used to develop constants which can provide the
investigator with a useful means of quantifying relative release
potential. The parameters most important when assessing the
volatilization of a constituent include the following:
o water solubility. The solubility in water indicates the
maximum concentration at which a constituent can dissolve
in water at a given temperature. This value can help
the investigator estimate the distribution of a constituent
between the dissolved aqueous phase in the unit and the
undissolved solid or immiscible liquid phase. Considered
in combination with the constituent's vapor pressure, it
can provide a relative assessment of the potential magni-
--- tude of volatilization of a constituent from an aqueous
environment (see discussion of Henry's Law constant
below).
o vapor pressure. Vapor pressure measures the pressure of
vapor in equilibrium with a pur_e liquid. It is best used
in a relative sense, constituents with high vapor pres-
sures are more likely to have significant releases than
th.ose with low vapor pressures, depending on other factors
such as relative solubility and concentrations (I.e. at
high concentrations significant releases can occur even
though a constituents vapor pressure is relatively low).
o octanol/water partition coefficient. The octanol/water
partition coefficient indicates th-e tendency of an organic
constituent to sorb to organic constituents in the soil
or waste matrices of a unit. Vapors with high octanol/
water partition coefficients will adsorb readily to organic
6-11
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Table 6-4
Parameters and Measures for Use in Evaluating
Potential Air Releases of Hazardous Waste Constituents
mission and Waste Type
A. Vapor Phase Emissions
-- Dilute Aqueous Solution2/
-- Cone. Aqueous Solution^/
-- Immiscible Liquid
— Solid
Units of
Concern!/
Surface Imp. ,
Tanks, Containers
Tanks, Containers,
Surface Imp.
Containers, Tanks
Landfills, Waste
Piles, Land Trt.
Useful Parameters
and Measures
. Particulate Emissions
— Solid
Landfills, Waste
Piles, Land Trt.
Solubility,
Vapor Pressure,
Partial Pressure,
Henry's Law
Solubility,
Vapor Pressure,
Partial Pressure,
Ra ou1ts Law
Va po r Pressure ,
Partial Pressure
Vapor Pressure,
Partial Pressure,
Oc tanol/Wa ter
Partition Coeff.
Particle Size
Distribution,
Si te Activi ties,
Management Methods
II
21
Incinerators are not specifically listed on this table because
of the unique issues concerning air emissions from these units.
Incinerators can burn all the forms of waste listed in this
table. the potential for release from these units is primarily
a function of incinerator operating conditions and emission
controls, rather than/waste characteristics.
Although the octanol/water partition coefficient of a constituent
is usually not an important characteristic in these waste streams,
there are conditions where it can be critical. Specifically, in
waste containing high concentrations of organic particulars, con-
stituents with high octanol/water partition coefficients will
adsorb to the particulates. They will become part of the sludge
or sediment matrix, rather than volatilizing from the unit.
Applicable to mixtures of volatile components.
6-12
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carbon, rather than volatilizing to the atmosphere. This
is particularly important in landfills and land treatment
units, where high organic carbon contents can significantly
reduce the release of vapor phase constituents.
o partial pressure. For constituents in a mixture, particu-
larly in a solid matrix, the partial pressure of a consti-
tuent will be more significant than the pure vapor pressure.
In general, the greater the partial pressure, the greater
the potential significance of the release. Partial
pressures will be difficult to obtain. However, when
waste characterization data is available partial pressures
can be calculated using methods commonly found in engi-
neering and environmental science handbooks.
The investigator should examine each of the above parameters
in combination with each other and with the specific characteris-
tics of the unit of interest. Several measures are available to
help the investigator with this assessment, provided they are
applied to the appropriate waste types and units. These measures
include:
o Henry's Law constant. Henry's law constant is the ratio
of the vapor pressure of a constituent and its aqueous
solubility (at equilibrium). It can be used to assess
the relative ease with which the compound may be removed
from the aqueous phase via vaporization. It is accurate
only when used concerning low concentration wastes in
aqueous solution. Thus it will be most useful when the
unit being assessed is a surface impoundment or tank con-
taining dilute wastewaters. Generally, when the value of
Henry's Law constant is less than 10E-7 atm-m^ the consti-
tuent will not volatilize from water. As the value
"-.-. increases the potential for significant vaporization
increases, and when it is greater than 10E-3 rapid vola-
tilization will.occur. Henry's Law constants for many
potentially significant constituents are listed in table
6-2.
o Raoult's Law - Raoult's Law can be used to predict re-
leases from concentrated aqueous solutions (i.e. solutions
over 10% solute). This will be most useful when the unit
of concern entails container storage, tank storage, or
treatment of concentrated waste streams.
For solid wastes, imiscible liquids, and wastes disposed of
in landfills, land treatment, or waste piles there are no simple
measures that can be used to assess the potential for volatilization
6-13
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of a constituent. The investigator will need to consider the
appropriate chemical, physical, and unit parameters, and then use
his/her best judgment in determining the potential for release.
Table 6-4 summarizes the chemical parameters the investigator
should consider when assessing the different waste physical
form/unit combinations.
Particulate emissions. The likelihood of particulate re-
leases at hazardous waste management facilities is generally
associated with landfills, land treatment units and/or waste
piles. The severity of particulate releases is governed by
different parameters than those that affect vapor-phase releases.
The primary physical parameter will be the particle size distri-
bution. Incinerators will always release some particulates in
the exhaust stack, and they may cover a wide range of sizes.
Information on the particle size distribution can be helpful in
assessing the potential risks to humans, as the primary concern
will be with the smaller, iahalable particulates.
Three mechanism are particularly important in the generation
of particulate releases at hazardous waste facilities, and the
investigator should examine the site for evidence that these
practices are occurring. They are:
o wind erosion; In general, the unit's location will
affect the potential for the wind to erode wastes in the
unit. The unit's location and orientation with respect
to the prevailing winds and large structures on site will
determine the unit's vulnerability to wind erosion and-
the potential for particulate releases. Agency personnel
should determine the location of SWMUs of concern with
respect to prevailing winds and the use of wind screens
(both natural and man-made) and daily covers to determine
the unit's vulnerability to wind erosion.
6-14
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o reentrainment by moving vehicles on soil, paved, and
unpaved roads: Vehicles moving on site can generate
fugitive dust emissions. Factors affecting dust emissions
generation include the amount of daily vehicular traffic
at the site and the average size of the vehicles.
o operational activities: These include the movement of
soils or hazardous wastes by dozers, loading by front-.end
loaders, and other activities associated with landfilling
or waste piles may cause fugitive dust emissions.
Potential for M 1 tigating Exposure
In assessing the potential significance of air releases from
a solid waste management unit or a facility with several units,
the investigator needs to consider several factors that act to
reduce the concentrations of airborne contaminants. Two classes
of factors are important:
o atmospheric/geographic conditions, which are directly
related to the amount of atmospheric dispersion available
for contaminant dilution; and
o contaminant specific factors, such as decay rates and
particulate size.
Both of these factors can significantly reduce the concentration
of released constituents, thereby reducing the importance of a
release. However, under some specific conditions, the effect of
these.factors is limited considerably.
Atmospheric/geographic factors. Atmospheric dispersion can
rapidly dilute the mass of a contaminant released from a solid
waste management unit. In many cases, a contaminant's concentra-
tion decreases as the distance from the source of release in-
creases. However, specific atmospheric conditions and geographic
factors can greatly limit the amount of dispersion. When asses-
sing air releases, the investigator needs to consider whether any
of these conditions are important at the site in question.
6-15
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Conditions and factors that limit dispersion include:
o narrow valleys and urban areas containing large buildings
(artificial canyons);
o areas dominated by off-shore breezes;
o areas with atmospheric conditions dominated by neutral
air stability; and
o areas with atmospheric conditions known to frequently
result in inversions (low average wind speeds, mountain
bas ins, etc.
All of these conditions contribute to higher than normal concen-
trations, thus increasing the significance of a release. The
investigator may be able to obtain some of this information from
local weather data bases as part of the preliminary assessment.
However, collection of this information will probably require a
site inspection.
Constituent-Specific Factors
Two important constituent-specific factors can also affect
the airborne concentration of a released contaminant. For vapor
phase contaminants, persistence is the most important factor, and
for particulate contaminants, particle size is the principal
conce rn.
The persistence of an airborne contaminant is primarily
governed by a constituent's photolysis rate. Pollutants with
high photolysis rates (i.e., those with an atmospheric half-life
of 1 day) will degrade rapidly, resulting in a significant
decrease in concentration and therefore exposure.
For particulate releases, the size distribution of the
particles in the release plays an important role in both dispersion
and actual exposure. Large particles will settle out of the air
more rapidly than small particles, thus they will not travel as
6-16
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far off-site or be diluted as much by dispersion. Very small
particles (i.e., those that are less than 5 microns in diameter),
are considered to be respirable and thus present a greater health
hazard than larger particles. Particulate releases containing a
high proportion of small particles are therefore of greatest
concern. The inspector should examine the source of the parti-
culate emissions to obtain information on particle size.
III. EVIDENCE OF AIRBORNE RELEASES
Positive identification of airborne contaminants at a site
is an important part of determining whether a significant air
release has occurred. However, because air releases are difficult
to observe and monitor, it will generally be difficult to make a
positive identification. In addition, it Is doubtful that
adequate monitoring data will be readily available for a specific
site. The investigator will most likely have to rely on
circumstantial evidence based on available data, or, in some
cases, on sampling data collected during the site investigation.
Available Data Co 1leetion Methods and Sources
The most useful information for determining if a release is
or has occurred is on-site monitoring data. As mentioned above,
It is unlikely that this type of information will be available
for most sites. Sources of this information Include the owner or
operator, EPA regional offices, state, county or local departments
of health, or OSHA. Even If this Information is available, the
investigator should carefully assess its usefulness, paying
particular attention to proper collection of background samples
and the time and weather conditions when samples were taken.
6-17
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Other useful data includes citizen complaints concerning both
odor and observed particulate emissions. It is important to note
however, that the absence of odor does not imply the absence of
vapor releases, since many constituents have high odor thresholds.
OSHA may have, in addition to air monitoring data, collected
health or personal monitoring data from site workers. This
information may also suggest the presence of a release.
The RQ1e o f S a m p 11 n g
EPA expects that in most cases, sampling will not be neces-
sary during the PA/SI to determine whether to conduct further
investigations at the unit for air releases. However, there may
be situations where the investigator may want to take samples or
require the owner or operator to take samples. For example,
the investigator may wish to obtain specific information on the
types and concentrations of specific hazardous constituents in
the unit to get a better indication of the potential magnitude of
an air release. Another reason to conduct sampling would be to
confirm a finding that a release or a potential air release from
the unit warrants further investigation.
The permit writer may choose to use monitoring equipment,
such as an organic vapor analyzer or a forced air particulate
filter, around the perimeter of the unit to confirm a suspected
release from a unit. However, without the proper collection of
background samples as well as time series sampling, the use of
such monitoring equipment during the course of a site inspection
can not confirm that a release is not taking place.
The investigator can require the owner or operator to sample
or monitor in certain situations. These are likely to be situa-
6-13
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tions where the Agency can specify the number and location of
samples, sampling or monitoring methods, and the procedures for
analyzing samples.
IV. POTENTIAL FOR EXPOSURE
Exposure information, to the extent It Is available for the
facility, will help in assessing whether and to what extent air
releases from the facility could affect human health and the
environment. Again, at this stage in the corrective action
process, the information and the analysis will largely be quali-
tative. However, this information can help in determining the
need to conduct further investigations, (e.g., depending on the
population density around the site); and in setting priorities
for the remedial investigation stage of the process.
Population density and distance from the source are the pri-
mary factors in determining the significance of a potential
exposure. Distance should be measured from the unlt(s) containing
the waste rather than from the facility boundary, although total
facility emissions from all solid waste management units must
also be kept in mind. Most Importantly, the investigator should
consider the density of the population residing within an approxi-
mately four-mile radius, as well as transients such as workers in
factories, offices, restaurants, motels, or students. Travelers
that pass through the area should not be included in any count.
The most significant exposure potential will occur in situa-
tions when there is a high population density within a 1/4 mile
radius of the site. However, because concentrations can be quite
high, even low density populations in such close proximity to the
site are of concern. Dispersion can significantly reduce concen-
6-19
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trations as distance from a site increases. Thus, the signi-
ficance of high population density at larger distances from the
site is reduced, particularly when the distance is four miles or
mo re.
The investigator needs to consider the relationship between
distance, concentration, and population density in evaluating the
significance of an exposure potential. An additional factor to
consider is the population located along the line of the most
predominant wind direction at a site. Because the PA/SI is
primarily concerned with continuous releases, populations located
along this line downwind of the site are more likely to receive
significant exposures than populations located along other vectors.
If the investigator determines that a solid waste management
unit is releasing large volumes of unsaturated hydrocarbons,
he/she may need to consider population density over a much larger
area than a four mile radius. These constituents contribute to
the formation of photochemical smog and ozone, which, in combina-
tion with other regional pollutant releases, can cause significant
exposures over a wide geographic area.
V. SUMMARY
This chapter has.identified a number of factors that affect
a facility's potential to have significant air releases that
warrant further investigation. These factors include:
o unit characteristics, such as size, type and use;
o types and characteristics of wastes placed in the unit; and
o the potential of locational factors and constituent-specific
factors to mitigate the significance of the release.
The first section of this chapter described all of these factors
6-20'
-------
in some detail in order to give the investigator a better basis
for determining whether a release is significant or not. While
many units can be expected to have air releases, most of these
releases -- either because of certain unit characteristics,
concentrations of specific constituents in the waste, atmospheTic
dispersion characteristics, distance to receptors, etc. --
will not be significant enough to warrant further investigation.
The investigator will need to consider each of the factors
described In Section I of this chapter in determining the potential
for significant releases from solid water management units at the
facili ty.
The investigator should use evidence (to the extent it is
available) that identifies the presence of releases and informa-
tion on the potential for human exposure to assist in making
these determinations.
Table 6-5 provides examples of situations that are likely to
require further Investigation and situations that probably will
not require further Investigation for air releases.
6-21
-------
Table 6-5
Uni t Illustrations
Unit Type
Surface
Impoundmen ts
(RCRA and non-
RCRA)
Further Investigation
Needed
Surface impoundments
that contain large
quantities of highly
volatile wastes listed
in Table 6-2
Further Investigation
Not Needed
Units closed by removal
of wastes
Units handling waste-
waters containing only
non-volatile metals
Open Roofed
Tank s
Landfills
Open tanks containing
large, quantities of
highly volatile wastes
listed in Table 6-2
Landfills with inade-
quate daily cover and
compaction operating
procedures in areas
with strong prevailing
winds in close prox-
imity to populations
Units treating or
storing wastewaters
containing only
non-volatile metals
Monofills of wastes
which contain only
non-volatile metals
and which use daily
cover and compaction
to control particulates
Monofills of wastes
containing only organic
constituents having
high oc tanol/wa ter
partition coefficients
and which use daily
cover and compaction
to control particulate
emi s s ions
Small landfills closed
in accordance with
closure provisions
in §264.310
Units which have been
closed for a long
.period of time and
that are being man-
aged using a stable
cover system
6-22
-------
Table 6-5 cont.
I
Unit Type
Land Treatment
Waste Piles
Drum 3 torage
Areas
Covered Tanks
Inci nera tors
II
Further Investigation
Needed
Land treatmet units
containing large quan-
tities of highly vola-
tile wastes described
in Table 6-2 and located
in areas with strong
prevailing winds and
nearby populations
Outdoor, uncovered waste
piles receiving large
quantities of wastes
described in Table 6-3
Outdoor storage areas
poorly maintained with
evidence of frequent open
drum storage, poorly
sealed drums, and/or
leaking drums containing
wastes described in Table
6-2.
Poorly maintained units
containing cracks,
corrosion, or poorly
sealed access ports
which contain large volumes
of highly volatile wastes
described in Table 6-2
All unpermitted units
Further Investigation
Not Needed
Closed units which
were used experi-
mentally or for. a
single application
of wa s te and for
which wind erosion
controls are being
used
Most indoor piles
Outdoor piles properly
covered, located in
areas which minimize
wind erosion, and
which contain only
constituents with very
low vapor pressures
Most indoor storage
areas
Well maintained out-
door storage areas
in which was tes
containing low vapor
pressure constituents
are stored
Most covered units
Well maintained and
permitted Incinerators
with inspection
records detailing
proper operation
By design all incinerators release gases and some particulate matter
Into the atmosphere. The investigator should thoroughly investigate
all units for improper and hazardous releases.
6-23
-------
APPENDIX MATERIAL
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-------
LIST 31
INDUSTRY SPECIFIC PARAMETERS
METALFINISHING
Parame ter
ch romi urn
copper
cyanide
Iron
zinc
trichloroe thene
tetrachloroethylene
vinyl c hlor ide
p henan threne
nickel
Chemical Abstract System Number
7440-47-3
7550-50-3
57-12-5
7439-89-6
7 44 u-6 6 - 6
79-01-6
127-18-4
75-01-4
85-01-8
-------
LIST B2
IRON AND STEEL
Parame te r
arsenic
ch romi urn
cyan ide
tin
zinc
benzene
benzo(a)pyrene
tetrachloroethylene
Chemical Abstract System Number
7440-38-2
7440-47-3
57-12-5
7440-31-5
7440-66-6
71-43-2
50-32-3
127-18-4
-------
LIST B3
PESTICIDES
Pa rame ter Chemical Abstract System Number
arsenic 7440-38-2
cyanide 57-12-5
copper 7550-50-8
benzene . 71-43-2
carbon tetrachloride 56-23-5
chlordane 57-74-9
chiorobenzene 67-66-3
chloroform 108-90-7
1,4-dichlorobenzene 106-46-7
2,4-dichlorophenol 120-83-2
heptachlor 76-44-8
hexachlorocyclopentadiene 77-47-4
methyl chloride 74-87-3
metbylene chloride 75-09-2
4-nitrophenol 100-02-7
phenol 103-95-2
tetrachloroethylene 127-13-4
coluane 103-33-3
Manufactured oesticides*
* A n y specific pesticides, residues, off-specification products,
or other sixiliar items known to have been disposed ot at the
sit-e, or, in the case of a dedicated facility, known to have been
manufactured at the site.
-------
LIST C
Parameter Chemical Abstract System Number
bis(2-ethylhexyl)phthalate 117-81-7
PCB-1016 12674-11-2
PCB-1221 11104-28-2
PCB-1232 11141-16-5
PCB-1248 12672-29-6
PCB-1254 11097-69-1
PCB-1260 11096-82-5
PCB-1242 ' 53469-21-9
arsenic 7440-38-2
benzene 71-43-2
ch lorobenzene 108-90-7
ethyl benzene 100-41-4
toluene 108-88-3
chromium 7440-47-3
copper 7550-50-8
cyanide 57-12-5
tetrachloroethylene 127-18-4
vinyl chloride 75-01-4
trichoroethylene 79-01-6
Iron - 7439-89-6
manganese 7439-96-5
naphthalene 91-20-3
nickel 7440-02-0
phananthrene is 5 - 0 1 - 3
phenol 108-95-2
Tine 7440-6-6
-------
Parame ter
3,3'-dichlorobenzidlne
be nz idene
endrin a Idehyde
bis(2-ethylhexyl)phthalate
bu tylbenzylphthalate
d 1-n-butylphthala te
di-n-octylphthalate
diethylphthala te
dimethylphthalate
hexachlorobutadiene
hexachlorocyclopentadiene
aldrin
M - n i trosodi-n-propylamlne
heptachlor expoxide
dieldrin
endrin
2-bu tanone
i sophorone
ace tone
acrolein
acrylonitrile
hep tachlor
chlordane
alpha-endosulfan
be ta-endosulfan
endosulfan sulfate
fluroene
aeenaphthaline
a cena ph thene
vinyl acetate
aluminum
anthracene
ant itnrony
PCB-1016
PCB-1221
PCB-1232
PCB-1248
PCB-1254
PCB-1260
PCB-1242
arsenic
ba r i urn
benzo(a)anthracene
3 ,4-benzofluoranthene
N-ni trosodiphenyla.nine
benzene
4,4'-DDE
4,4'-DDD
1 , 2,4-trichlorobenzene
1 ,2-dichlorobenzene
LIST D
Chemical Abstract System Number
91-94-1
92-87-5
7421-93-4
117-81-7
85-68-7
84-74-2
117-84-0
84-66-2
131-11-3
87-68-3
77-47-4
309-00-2
621-64-7
1024-57-3
60-57-1
72-20-8
78-93-3
78-59-1
67-64-1
107-02-8
107-13-1
76-44-3
37-74-9
115-29-7
115-29-7
1031-07-8
3 o - 7 3 - 7
ZJ'S-^o-j
83-32-9
103-05-4
7429-90-5
120-12-7
7440-36-0
12674-11-2
11104-23-2
11141-16-5
12672-29-6
11097-69-1
11096-32-5
53469-21-9
7440-38-2
7440-39-3
56-55-3
205-99-2
86-30-6
71-43-2
72-55-9
72-54-8
120-82-1
95-50-1
-------
LIST D (Continued)
Parame ter
1,3-dichlorobenzene
1,4-dichlorobenzene
4,A'-DDT
4-bromophenylphenylether
4-chlorophenylphenylether
2,4-d in i trotoluene
2,6-dinltrotoluene
c hiorobe nzene
e thylbenzene
hexachiorobenzene
toluene
ni trobenzene
benzo(a)pyrene
benzo(ghi)perylene
benzo(k)fluoranthene
beryllium
cadmi urn
caIc i urn
carbon disulfide
chromi urn
ch ry sene
cobalt
copper
cyan ide
alpha-sac
beta-BHC
del ta-3HC
ga.n.-.a-3HC
dibenzo(a,h)anthracene
2,3,7,8-TCDD
bis(2-chloroethoxy)me thane
bis(2-chloroethyl)ether
1,1, 1 "r,trichloroe thene
1,1,2,2-tetrachloroethylene
1,1,2-trIchloroethene
1,1-dichloroethene
1 , 2-dichloroe thene
c hio roe thane
hexachloroethene
2-chloroethylviny1 ether
1, 1-dichloroethylene
1,2-dichloroethylene
vinyl chloride
tetrachloroethylene
t r ichloroe thene
flouroan thene
1,2-diphenylhydrazine
indeno(l,2,3-cd)pyrene
iron
lead
Chemical Abstra c t System Number
541-73-1
106-46-7
50-29-3
101-55-3
7005-72-3
121-14-2
606-20-2
108-90-7
100-41-4
118-71-1
108-88-3
98-95-3
50-32-8
191-24-2
207-08-9
7440-41-7
7440-43-9
7400-70-2
75-15-0
7440-47-3
213-01-9
7440-48-4
7550-50-3
57-12-5
319-34-b
319-85-7
319-S6-S
53-3J-S
53-70-3
1746-01-6
11 1-91-1
111-44-4
71-55-6
79-34-5
79-00-5
75-34-3
107-06-2
75-00-3
67-72-1
110-75-8
75-35-4
156-60-5
75-01-4
127-18-4
79-01-6
206-44-0
122-66-7
193-39-5
7439-89-6
7439-97-6
-------
LIST D (Continued)
Parameter
ma gne s I urn
manganese
me rcu ry
n-ni trosod ime thylamine
me thyl bromide
dichlorobromomethane
methyl chloride
chlorodibromomethane
methylene chloride
dichlorodifluoromethane
carbon tetrachloride
bromo fo rm
chloroform
trichloro fluoromethane
naphthalene
2-chloronaphthalene
nickel
phenan threne
phenol
2,4,5-trichloropnenol
2,4,6-trichlorophenol
2,4-dichlorophenol
2 , 4-d i me thylphenol
2 , 4-d in i trophenol
2-chlo rophenol
4,6-dini tro-o-cresol
2-n i t rophenol
p-chloro-m-cresol
4-me thylphenol
4-ni trophenol
pentachlorophenol
po tass i urn
1,2-dichloropropane
bis(2-chloroisopropylether)
1,2-dichloropropylene
p y r e n e
selenium
s ilve r
sodium
thalli urn
tin
toxaphene
va nad iurn
zinc
Chemical Abstract System Number
7439-95-4
7439-96-5
7439-97-6
62-75-9
74-33-9
75-27-4
74-87-3
124-48-1
75-09-2
75-71-8
56-23-5
75-25-2
67-66-3
75-69-4
91-20-3
91-53-7
7440-02-0
-35-01-8
108-95-2
95-95-4
88-06-2
120-83-2
105-67-9
51-2S-5
95-57-8
534-52-1
83-75-5
59-50-7
106-44-5
100-02-7
87-86-5
7440-09- 7
78-87-5
39633-32-9
542-75-6
129-00-0
7782-49-2
7440-22-4
7440-23-5
7440-28-0
7440-31-5
8001-35-2
7440-62-2
7440-66-6
-------
SAMPUNG PRIORITIES FOR ENVIRONMENTAL POLLUTANTS
Compounds are characterized on the basis of persistence, accumulative capacity and
volatility. "X" indicates the appropriate environmental compartments) for initial
sampling.
Environmental Compartment
Compound
Water
Sediment
Biota
METALS AND INORGANICS
Antimony
Arsenic
Asbestos
Beryllium
Cadmium
Chromium
Copper
Cyanides
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
PESTICIDES
Acrolein
Aldrin
Chlordane
000
DOE
DOT
Dieldrin
Endosulfan and endosulfan sulfate
Endrin and endrin aldehyde
Heptachlor
Heptachlor epoxide
Hexachlorocyclohexane (a,8,5 isomers)
Y-Hexachlorocyclohexane (lindane)
Isophorone
TCDO
Toxaphene
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
D
WPF 2/1/85
Page 9 of 11
REFERENCED STANDARD OPERATING
GUIDELINES FOR PROJECT ACTIVITIES
Please check off the following tasks that will be performed during the course of
the project. Then, at the bottom of the page and on subsequent pages, describe
fully, for each task, the appropriate procedures and actions that will be taken
to provide both quality assurance and quality control. If a given task has
standard operating guidance (SOG) that is documented, please refer to that
guidance. The primary reference would be State Agency Standard Operating
Procedures. List others as appropriate.
Document/Section Description
Ambient Air Sampling (OVA, HNU, etc.)
Ground-Water Sampling
Surface-Water Sampling
Soil/Sediment Sampling
Tap Water Sampling
___________________ Land Surveying
Electrical Resistivity Survey
Electromagnetic Survey
Magnetometer Survey
Metal Detection Survey
Ground Penetrating Radar Survey
' Seismic Survey
Water Level Measurements
Perimeter Survey
Site Inspection
Soil Borings/Well Installation
Bedrock Fracture Analysis
Pump/Permeability Tests
Preparation of Water Table Maps
Preparation of Bedrock Contour Maps
-------
WPF 2/1/85
Page 11 of 11
APPLICABILITY
The folk>wing portions of the NUS Superfund Division Quality Assurance Manual
are applicable to the performance of specific work elements defined in
TDD /MM i"o StaVe. • The quality assurance procedures recognized in Region II
FIT follow applicable operating guidelines provided in the preeceeding section of •
this work plan.
( ) Number Subject
QAP 2.5 Work Plans
QAP 3.1 Control of Remedial Design Activities
QAP 4.1 Field Data Collection
QAP 4.2 Data Reduction, Validation, and Reporting
QAP 5.1 Preparation of Procurement Documents
QAP 5.2 Subcontractor Quality Assurance Requirements
QAP 6.1 Preparation of Instructions and Procedures
QAP 7.1 Identification of Controlled Evidentiary
Documents
QAP 7.2 Issuance and Distribution of Controlled
Documents
QAP 7.3 Development, Documentation, Verification, and
Retention of Software Programs
QAP 7.4 Technical Reports
QAP 7.5 Interim Document Review Procedure
QAP 8.1 Control of Procurement Activities
QAP 8.2 Evaluation and Selection of Subcontractors
QAP 9.1.F2 Chain of Custody
QAP 9.2.F2 Sample Control
QAP 10.1 Analysis Techniques
QAP 11.1 Off site Reconnaissance
QAP 11.2 Onsite Inspections
QAP 12.1 Implementation of Measuring and Test Equipment Controls
Materials
QAP 13.1 Packaging, Marking, Labeling, and Shipping of
Samples from Hazardous-Waste Sites
QAP 14.1 Nonconformance Reporting, Evaluation, and
Disposition
QAP 15.1 Implementation and Documentation of Corrective
Actions
QAP 16.1 Storage and Retrieval of Quality Assurance
Records
QAP 17.4 Preparation for Audit
QAP 17.6 Quality Notices
-------
SAMPLING PRIORITIES FOR ENVIRONMENTAL POLLUTANTS
PAGE THREE
Compound
Environmental Compartment
Water Sediment Biota
ETHERS (Continued)
8is(2-chloroisopropyl)ether
2-Chloroethyl vinyl ether
4-Chlorophenyl pnenyl ether
4-Sromopheny! phenyl ether
Bis(2-chloroethoxy) methane
MONOCYCUC AROMAT1CS
Benzene
Chlorobenzene
1,2-Dichlorobenzene (o-dichlorobenzene)
1,3-Dichlorobenzene (m-dichlorobenzene)
1,4-Oichlorobenzene (p-dichlorobenzene)
1,2,4-Trichlorobenzene
Hexachlorobenzene
Ethylbenzene
Nitrobenzene
Toluene
2,4-Oinitrotoluene
2.6-Dinitrotoluene
PHENOLS AND CRESOLS
Phenol
2-Chlbrophenol
2.4-Oichlorophenol
2.4,6-Trichlorophenol
Pentachtorophenol
2-Nitrophenol
4-Nitrophenol
2.4-Oinitrophenol
2.4-Oimethylphenol
p-Chloro-m-cresol
4,6-Dinitro-p-cresol
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
These compounds have been removed from the EPA priority pollutant list
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EXPENDABLE EQUIPMENT
Quantity Amount
Packag
Item Packaged Required
CHEMICALS
Acetone 5 gal.
Acetone 1 gal.
Trichloroe thane 5 gal.
Trichloroethane 1 gal.
Methylene-chloride 5 gal.
Methylene-chloride 1 gai.
Hexane 1 gal.
Gasoline 1 gal.
Gasoline 5 gal.
Nitric Acid 1 gal.
Nitric Acid 5 ml.
Sodium Hydroxide 1 liter
Motor Oil I qt.
2-Cycle Oil 1/2 pt.
Alconox 1 gal.
Baking Soda 2 Ib. box
SAMPLE CONTAINERS
*0 ml. VOA Bottles 1 each
Yt gai. Amber Bottle 1 each
I liter Amber Bottle 1 each
S oz. Glass Jars 1 each
1 liter Plastic Bottles 1 each
Plastic Bags S" x 12" 100 box
Plastic Bags 10" x 12" 100 box
Plastic Bags 12" x 20" 100 box
Paint Cans w/lid dc snaps 1 gal.
Paint Cans w/lid
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EXPENDABLE EQUIPMENT (Conf d)
Quantity Amount
Item Packaged Required
FILM
C-13J-36-100-Prints I roll
C-l 35-36- 200-Prints 1 roll ZZHHZ
C-135-36-400-Prints 1 roll 3.
C-l 35-2*-100-Prints 1 roll
C-135-20-200-Prints l roll H~~'
C-l35-2*-400-Prints 1 roll HUZZ
C-135-l2-100-Prints i roll ZZIZZ
C-135-l2-200-Prints l roll ZZZZZ
C-13M2-*00-Prints 1 roll ZZZZH
C-135-36-20Q-Slide 1 roll
C-135-36-25-SUde 1 roll £j_
BAW-l35-20-400-Prints I roll
SX-70 Polaroid I sgl. pack
Kodamatic l sgl. pack
STATIONERY SUPPLIES
Graph Paper
Manilla Tags
Paper Towels
Felt Tip Markers
Ball Point Pens
Indelible Ink Pens
ROPE
Nylon 3/16" 600'roll
Nylon \l<4" 1000' roll
Manila I/* 100' roll
Manila 1/2 50' roll
TAPE
Clear Plastic l each
Duct 1 roil
Elec. Vinyl l roll
Filament 1 roll
Flagging 100' roll
Masking 1 roll
Transparent l each
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NON-EXPENDABLE EQUIPMENT
Equipment Amount Required
CAMERAS
Cannon AEi
Polariod One Step
Polaroid SX70
Camera bag
Binoculars
AIR MONITORING
HNU Photoionization Detector
Draeger Tubes Type /* <^w -> ^? g q
Organic Vapor Analyzer /
OVA Chart Recorder ____
Explosimeter /
Combination Explosimeter and O? Indicator
Oxygen Indicator /
Draeger Tube Hand Pump ' /
H2S Gas Indicator /
Mercury Sniffer ______.
Photovac
METERS
Radiation Mini-Alert
Conductivity Meter
pH Meter
Resistivity Meter (Bison)
Resistivity Meter (Soil Test)
Metal Detector
SURVEYING EQUIPMENT
Optical Rangefinder
Level, Hand 2X
Brunton Transit w/case
Compass
200' Fiberglass Measuring Tape
300' Fiberglass Measuring Tape
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NON-EXPENDABLE EQUIPMENT (conf d)
Equipment Amount Required
POWER EQUIPMENT
Digger Mobile
3 HP Water Pump w/gas can
Generator w/gas can
Power Auger w/gas can
Extension Cord-Heavy Duty 100"
Extension Cord-Light Duty 25"
Remote Drum Opener
PERSONAL PROTECTION
Hard Hat
Safety Goggles
Safety Glasses
Splash Shield
Full Face Respirator
Respiratory Cartridges
Butyl Rubber Apron
Encapsulated Suits
Life Vests
Rain Jacket
Rain Pants
SELF CONTAINED BREATHING APPARATUS
401 SCBA
Dual Purpose SCBA <*"
CASCADE System ~
45 cu. ft. Composite Tanks : / Q
Umbilical Breathing Air Lines (50* Sec)
Umbilical Breathing Air System
330 cu. ft. Class "D" Breathing Air Cylinder
STANDBY SAFETY EQUIPMENT
20// Fire Extinguishers
Oj Resuscitator
Stretcher
Eye Wash
Trauma Kit
-------
t
UNITED STATEbE-'V-rNMENTAl. PROTECTION AGENCY Pa'e^M-S
,V ASH .NO TON DC 20460
NOV I 9 JS84
iOUlO WASTE ANO *•."*• -Gc'tC ' *«.'•
MEMORANDUM
SUBJECT: Standard Operating Safety Guides, November 1984
FROM: William N. Hedeman, Jr., Director
Office of Emergency and Remedial R
TO: Regional Office Addressees
The enclosed Standard Operating Safety Guides, November 1984
replaces the Interim Standard Operating Guides, Revised
September 1982. The Guides have been updated and revised to
reflect additional experience EPA personnel have gained in
responding to environmental incidents involving hazardous
substances.
The Standard Operating Safety Guides are in accordance and
consistent with the procedures for employee health and safety
contained in EPA's Occupational Health and Safety Manual,
Chapter 9, Hazardous Substances Responses, (1440 TN12).
May 5, 1984.
The guides are not meant to be a comprehensive safety
manual for incident response. Rather, they provide information
on health and safety to complement professional judgement ar.d
experience, and to supplement existing Regional office safety
procedures.
If you have any questions or comments concerning the
guides, please contact Mr. Stephen Lingle, Director, Hazardous
Response Support Division or Mr. J. Stephen Dorrler, Chief,
Environmental Response Tea™.
Enclosure
Addressees
Director, Ofc. of Emergence & Remedial Resp. , Region II
Director, Hazardous Waste Mgmt. Div., Region III
Director, Air & Waste Management Division,
Regions IV, VI, VII. VIII
Director, Waste Mgmt. Div., Regions I & V
Director, Toxics & Waste Mgmt. Div., Region IX
Director, Air & Waste Division X
cc: Gene Lucero, OWPE
John Skinner, OSW
M-3
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1/11/85
Jew Paqe M-5
- Address emergency medical care for injuries and toxicological
problems.
- Describe requirements for an environmental surveillance program..
- Specify any routine and special training required for responders.
- Establish procedures for protecting workers from weather-related
problems.
III. SITE SAFETY PLAN SCOPE AND DETAIL
The plan's scope, detail, and length is based on:
- Information available about the incident.
- Time available to prepare a site-specific plan.
- Reason for responding.
Three general categories of response exist - emergencies, character-
izations and remedial actions. Although considerations for personnel
safety are generic and independent of the response category, in
scope, detail, and length safety requirements and plans vary consfd-
erably. These variations are generally due to the reason for
responding (or category of response) , information available, and the
severity of the incident with its concomitant.dangers to the respon-
der.
A. Emergencies
1. Situation:
Emergencies generally require prompt action to prevent or
reduce undesirable affects. Immediate hazards of fire, explo-
sion, and release of toxic vapors or gases are of prime
concern. Emergencies vary greatly in respect to types and
quantities of material, numbers of responders, type of work
required, population affected, and other factors. Emergencies
last from a few hours to a few days.
- Information available: Varies from none to much. Usually
information about the chemicals involved and their associ-
ated hazards is quickly obtained in transportation-related
incidents, or incidents involving fixed facilities. Deter-
mining the substances involved in some incidents, such as
mysterious spills, requires considerable time and effort.
- Time available: Little time, generally requires prompt
action to bring the incident under control.
- Reason for response: To implement prompt and immediate
9-2
M-5
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1/11/85
New Page M-7
C. Remedial Actions
1. Situation:
Remedial actions are cleanups which last over a long period
of time. They commence after more immediate problems at an
emergency have been controlled, or they involve the mitigation
of hazards and restoration of abandoned hazardous waste
sites. Numerous activities are required involving many people
a logistics and support base, extensive equipment, and more
involved work activities. Remedial actions may require months
to years to completely accomplish.
- Information available: Much known about on-site hazards.
- Time available: Ample time for work planning.
- Reason for response: Systematic and complete control,
cleanup, and restoration.
2. Effects on Plan:
Since ample time is available before work commences, site
safety plan tends to be comprehensive and detailed. From
prior investigations much detail may be known about the ma-
terials or hazards at the site and extent of contamination.
IV. SITE SAFETY PLAN DEVELOPMENT
To develop the plan as much background information as possible should
be obtained, time permitting, about the incident. This would include,
but not be limited to:
- Incident location and name.
----- Site description.
- Chemicals and quantities involved.
- Hazards associated with each chemical.
- Behavior and dispersion of material involved.
•
- Types of containers, storage, or transportation methods.
- Physical hazards.
- Prevailing weather condition and forecast.
- Surrounding populations and land use.
- Ecologically sensitive areas.
9-4
M-7
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1/11/35
New Paqe M-9
- Designate Levels of Protection to be Worn
The Levels of Protection to be worn at locations on-site or by
work functions must be designated. This includes the specific
types of respirators and clothing to be worn for each level. No
one shall be permitted in areas requiring personnel protective
equipment unless they have been trained in its use and are wearing
it.
- Delineate Work Areas
Work areas (exclusion zone, contamination reduction zone, and
support zone) need to be designated on the site map and the map
posted. The size of zones, zone boundaries, and access control
points into each zone must be marked and made known to all site
workers.
- List Control Procedures
Control procedures must be implemented to prevent unauthorized
access. Site security procedures - fences, signs, security pa-
trols and check-in procedures - must be established. Procedures
must also be established to control authorized personnel into work
zones where personnel protection is required.
- Establish Decontamination Procedures
Decontamination procedures for personnel and equipment must be es-
tablished. Arrangements must also be made for the proper disposal
of contaminated material, solutions, and equipment.
- Address Requirements for an Environmental Surveillance Program
A program to monitor site hazards must be implemented. This would
include air monitoring and sampling, and other kinds of media
sampling at or around the site that would indicate chemicals
present, their hazards, possible migration, and associated safety
requirements.
- Specify Any Routine and Special Training Required
Personnel must be trained not only in general safety procedures and
use of safety equipment, but in any specialized work they may be
expected te do.
- Establish Procedures for Weather-Related Problems
Weather conditions can affect site work. Temperature extremes,
high winds, storms, etc. impact on personnel safety. Work prac-
tices must be established to protect workers from the effects of
weather and shelters provided, when necessary. Temperature ex-
tremes especially heat and its effect on people wearing protec-
tive clothing, must be considered and procedures established to
monitor for and minimize heat stress.
9-6
M-9
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1/11/85
New Paae M-ll
- Address emergency medical care.
— Determine location of nearest medical or emergency care
facility. Determine their capability to handle chemical
exposure cases.
-- Arrange for treating, admitting, and transporting of injured
or exposed workers.
— Post the medical or emergency care facilities location, travel
time, directions, and telephone number.
« Determine local physician's office location, travel directions,
availability, and post telephone number if other medical care
is not available.
-- Determine nearest ambulance service and post telephone number.
— List responding organization's physicians, safety officers, or
toxicologists name and telephone number. Also include nearest
poison control center, if applicable.
— Maintain accurate records on any exposure or potential exposure
of site workers during an emergency (or routine operations).
The minimum amount of information needed (along with any
medical test results) for personnel exposure records is con-
tained in Annex 8.
- Advise workers of their duties during an emergency. In particular,
it is imperative that the site safety officers, standby rescue
personnel, decontamination workers, and emergency medical techni-
cians practice emergency procedures.
- Incorporate into the plan, procedures for the decontamination of
injured workers and for their transport to medical care facilities.
Contamination of transport vehicles, medical care facilities, or
of medical personnel may occur and should be addressed in the
plan. Whenever feasible these procedures should be discussed with
appropriate medical personnel in advance of operations.
- Establish procedures in cooperation with local and state officials
for evacuating residents who live near the site.
•
VII. IMPLEMENTATION OF THE SITE SAFETY PLAN
The site safety plan, (standard operating safety procedure or a
generic safety plan for emergency response) must be written to avoid
misinterpretation, ambiguity, and mistakes that verbal orders cause.
The plan must be reviewed and approved by qualified personnel. Once
the safety plan is implemented, its needs to be periodically examined
and modified, if necessary, to reflect any changes in site'-work and
conditions.
9-8
M-ll
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/Uo- A
/ x r
Sanple Tag
N 1000
IN.«*
AMLTttS
too
l*n
COO. TOC
>'. r*
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CUSTODY SEAL
Signature
Exaapl* of EPA Chain-of-Custody S«al
U.S. Environmental Protection Agency
Region 5, Ll^rury (6PL-K-)
230 S. Dearocrn St'eet, Room 1G70
, 1L 60604
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