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Guide For Industrial Waste Management
EPA530-R-03-001
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
1200 Pennsylvania Avenue, Ariel Rios Building, NW
Washington, DC 20460
February 2003
Printed on paper containing at least 50% postconsumer recovered fiber.
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Acknowledgements
Acknowledgements
The following members of the Industrial Waste Focus Group and the.Industrial Waste
Steering Committee are gratefully acknowledged for all of their time and assistance in the
development of this guidance document.
Current Industrial Waste Focus Group Members
Paul Bork, The Dow Chemical Company
Walter Carey, Nestle, USA, Inc. and New Milford Farms
Rama Chaturvedi, Bethlehem Steel Corporation
H.C. Clark, Rice University
Barbara Dodds, League of Women Voters
Chuck Feerick, ExxonMobil Corporation
Stacey Ford, ExxonMobil Corporation
Robert Giraud, DuPont Company
John Harney, Citizens Round Table/PURE
Kyle Isakower, American Petroleum Institute
Richard Jarman, National Food Processors Association
James Meiers, Cinergy Power Generation Services
Scott Murto, General Motors and American Foundry Society
James Roewer, Edison Electric Institute
Edward Repa, Environmental Industry Association
Tim Saylor, International Paper
Amy Schaffer, Weyerhaeuser
Ed Skemolis, WMX Technologies, Inc.
Michael Wach, Western Environmental Law Center
David Wells, University of South Alabama Medical Center
Observer:
Pat Gwin, Cherokee Nation of Oklahoma
Past Industrial Waste Focus Group Members
Doris Cellarius, Sierra Club
Brian Forrestal, Laidlaw Waste Systems
Jonathan Greenberg, Browning-Ferris Industries
Michael Gregory, Arizona Toxics Information and Sierra Club
Andrew Miles, The Dexter Corporation
Gary Robbins, Exxon Company
Kevin Sail, National Paint & Coatings Association
Bruce Steiner, American Iron & Steel
Lisa Williams, Aluminum Association
Current Industrial Waste Steering Committee Members
Kerry Callahan, Association of State and Territorial Solid Waste Management Officials
Marc Crooks, Washington State Department of Ecology
Cyndi Darling, Maine Department of Environmental Protection
Jon Dilliard, Montana Department of Environmental Quality
Anne Dobbs, Texas Natural Resources Conservation Commission
III.
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Acknowledgements
Acknowledgements (cont.)
Richard Hammond, New York State Department of Environmental Conservation
Elizabeth Haven, California State Waste Resources Control Board
Jim Hull, Missouri Department of Natural Resources
Jim Knudson, Washington State Department of Ecology
Chris McGuire, Florida Department of Environmental Protection
Gene Mitchell, Wisconsin Department of Natural Resources
William Pounds, Pennsylvania Department of Environmental Protection
Bijan Sharafkhani, Louisiana Department of Environmental Quality
James Warner, Minnesota Pollution Control Agency
Robert Dellinger, U.S. EPA
Thea McManus, U.S. EPA
Barnes Johnson, U.S. EPA
Richard Kinch, U.S. EPA
Paul Cassidy, U.S. EPA
John Sager, U.S. EPA
Charlotte Bertrand, U.S. EPA
Ann Johnson, U.S. EPA
David Cozzie, U.S. EPA
Tim Taylor, U.S. EPA
Shen-Yi Yang, U.S. EPA
David Layland, U.S. EPA
Past Industrial Waste Steering Committee Members
Pamela Clark, Maine Department of Environmental Protection
Norm Gumenik, Arizona Department of Environmental Quality
Steve Jenkins, Alabama Department of Environmental Management
Jim North, Arizona Department of Environmental Quality
Pat Cohn, U.S. EPA
Dwight Hlustick, U.S. EPA
Ginny Cohen-Bradley, U.S. EPA
Mark Schuknecht, U.S. EPA
This Guide, CD-ROM, and the ground-water and air modeling tools were finalized with
assistance from Eastern Research Group (Birute Vanatta, David Frank, and Kimberly Ferguson),
HydroGeologic, Inc. (Jan. Kool, Dua Guvansen, Ted Lillys, and Julie Feeney), Resource
Management Concepts, Inc. (Reid Rosnick), and Research Triangle Institute (Anne Cook Lutes,
Terrence Pierson, Susan Wolf, Robert Truesdale, Tony Marimpietri, Jeff Coburn, Jo Ellen
Brandmeyer, and Jesse Baskir).
IV.
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Contents
Contents
Introduction
Part I Getting Started
1 Understanding Risk and Building Partnerships
2 Characterizing Waste
3 Integrating Pollution Prevention
4 Considering the Site
Part II Protecting Air Quality
5 Protecting Air Quality
Part III Protecting Surface Water
6 Protecting Surface Water
Part IV Protecting Ground Water
7A Assessing Risk
7B Designing and Installing Liners: Technical Considerations for New Surface Impoundments, Landfills, and
Waste Piles
7C Designing a Land Application Program
Part V Ensuring Long-Term Protection
8 Operating the Waste Management System
9 Monitoring Performance
lOTaking Corrective Action
11 Performing Closure and Post-Closure Care
Glossary
v.
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Introduction
EPA's Guide for Industrial Waste Management
Introduction
Welcome to EPA's Guide for Industrial Waste Management. The pur-
pose of the Guide is to provide facility managers, state and tribal
regulators, and the interested public with recommendations and
tools to better address the management of land-disposed, non-haz-
ardous industrial wastes. The Guide can help facility managers make
environmentally responsible decisions while working in partnership
with state and tribal regulators and the public. It can serve as a
handy implementation reference tool for regulators to complement
existing programs and help address any gaps. The Guide can also
help the public become more informed and more knowledgeable in
addressing waste management issues in the community.
In the Guide, you will find:
• Considerations for siting industrial waste management units
• Methods for characterizing waste constituents
• Fact sheets and Web sites with information about individual waste constituents
• Tools to assess risks that might be posed by the wastes
• Principles for building stakeholder partnerships
• Opportunities for waste minimization
• Guidelines for safe unit 'design
• Procedures for monitoring surface water, air, and ground water
« Recommendations for closure and post-closure care
Each year, approximately 7.6 billion tons of industrial solid waste are generated and disposed
of at a broad spectrum of American industrial facilities. State, tribal, and some local governments
have regulatory responsibility for ensuring proper management of these wastes, and their pro-
grams vary considerably. In an effort to establish a common set of industrial waste management
guidelines, EPA and state and tribal representatives came together in a partnership and developed
the framework for this voluntary Guide. EPA also convened a focus group of industry and public
interest stakeholders chartered under the Federal Advisory Committee Act to provide advice
throughout the process. Now complete, we hope the Guide will complement existing regulatory
programs and provide valuable assistance to anyone interested in industrial waste management.
VII.
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Introduction
What Are the Underlying Principles of the Guide?
When using the Guide for Industrial Waste Management, please keep in mind that it reflects
four underlying principles:
• Protecting human health and the environment. The purpose of the Guide is to pro-
mote sound waste management that protects human health and the environment. It
takes a multi-media approach that emphasizes surface-water, ground-water, and air
protection, and presents a. comprehensive framework of technologies and practices that
make up an effective waste management system.
• Tailoring management practices to risks. There is enormous diversity in the type
and nature of industrial waste and the environmental settings in which it is managed.
The Guide provides conservative management recommendations and simple-to-use
modeling tools to tailor management practices to waste- and location-specific risks. It:
also identifies in-depth analytic tools to conduct more comprehensive site-specific
analyses.
• Affirming state and tribal leadership. States, tribes, and some local governments
have primary responsibility for adopting and implementing programs to ensure proper
management of industrial waste. This Guide can help states, tribes, and local govern-
ments in carrying out those' programs. Individual states or tribes might have more
stringent or extensive regulatory requirements based on local or regional conditions or
policy considerations. The Guide complements, but does not supersede, those regula-
tory programs; it can help you make decisions on meeting applicable regulatory
requirements and filling potential gaps. Facility managers and the public should con-
sult widi the appropriate regulatory agency throughout the process to understand regu-
latory requirements and how to use this Guide.
• Fostering partnerships. The public, facility managers, state and local governments,
and tribes share a common interest in preserving quality neighborhoods, protecting the
environment and public health, and enhancing the economic well-being of the commu-
nity. The Guide can provide a common technical framework to facilitate discussion and
help stakeholders work together to achieve meaningful environmental results.
What Can I Expect to Find in the Guide?
The Guide for Industrial Waste Management is available in both hard-copy and electronic ver-
sions. The hard-copy version consists of five volumes. These include the main volume and four
supporting documents for the ground-water and air fate-and-transport models that were devel-
oped by EPA specifically for this Guide. The main volume presents comprehensive information
and recommendations for use in the management of land-disposed, non-hazardous industrial
waste that includes siting the waste management unit, characterizing the wastes that will be
disposed in it, designing and constructing the unit, and safely closing it. The other four vol-
umes are the user's manuals and background documents for the ground-water fate-and-trans-
port model—the Industrial Waste Evaluation Model (IWEM)—and the air fate-and-transport
model—the Industrial Waste Air Model (IWAIR).
VIM.
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Introduction
The electronic version of the Guide, which can be obtained either on CD-ROM or from EPA's
Web site , contains a large collection of
additional resources. These include an audio-visual tutorial for each main topic of the Guide;
the IWEM and IWAIR models developed by EPA for the Guide; other models, including the
HELP (Hydrologic Evaluation of Landfill Performance) Model for calculating infiltration rates;
and a large collection of reference materials to complement the information provided in each of
the main chapters, including chemical fact sheets from the Agency for Toxic Substances and
Disease Registry, links to Web sites, books on pertinent topics, copies of applicable rules and
regulations, and lists of contacts and resources for additional information. The purpose of the
audio-visual tutorials is to familiarize'users with the fundamentals of industrial waste manage-
ment and potentially expand the audience to include students and international users.
The IWEM and IWAIR models that come with the electronic version of the Guide are critical
to its purpose. These models assess potential risks associated with constituents in wastes and
make recommendations regarding unit design and control of volatile organic compounds to
help mitigate those risks. To operate, the models must first be downloaded from the Web site or
the CD-ROM to the user's personal computer.
What Wastes Does the Guide Address?
The Guide for Industrial Waste Management addresses non-hazardous industrial waste subject
to Subtitle D of the Resource Conservation and Recovery Act (RCRA). The reader is referred to
the existence of 40 CFR Part 257, Subparts A and B, which provide federal requirements for
non-hazardous industrial waste facilities or practices. Under RCRA, a waste is defined as non-
hazardous if it does not meet the definition of hazardous waste and is not subject to RCRA
Subtitle C regulations. Defining a waste as non-hazardous under RCRA does not mean that the
management of this waste is without risk.
This Guide is primarily intended for new industrial waste management facilities and units,
such as new landfills, new waste piles, new surface impoundments, and new land application
units. Chapter 7B-Designing and Installing Liners, and Chapter 4-Considering the Site, are
clearly directed toward new units. Other chapters, such as Chapter 8-Operating the Waste
Management System, Chapter 9—Monitoring Performance, Chapter 10-Taking Corrective
Action, Chapter 11-Performing Closure and Post-Closure Care, while primarily intended for
new units, can provide helpful information for existing units as well.
What Wastes Does the Guide Not Address?
The Guide for Industrial Waste Management is not intended to address facilities that primarily
handle the following types of waste: household or municipal solid wastes, which are managed
in facilities regulated by 40 CFR Part 258; hazardous wastes, which are regulated by Subtitle C
of RCRA; mining and some mineral processing wastes; oil and gas production wastes; mixed
wastes, which are solid wastes mixed with radioactive wastes; construction and demolition
debris; and non-hazardous wastes that are injected into the ground by the use of shallow
underground injection wells (these injection wells fall under the Underground Injection Control
(UIC) Program).
IX.
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Introduction
Furthermore, while the Guide provides many tools for assessing appropriate industrial waste
management, the information provided is not intended for use as a replacement for other exist-
ing EPA programs. For example, Tier 1 ground-water risk criteria can be a useful conservative
screening tool for certain industrial wastes that are to be disposed in new landfills, surface
impoundments, waste piles, or land application units, as intended by the Guide/These
ground-water risk criteria, however, cannot be used as a replacement for sewage sludge stan-
dards, hazardous waste identification exit criteria, hazardous waste treatment standards, MCL
drinking water standards, or toxicity characteristics to identify when a waste is hazardous—all
of which are legally binding and enforceable. In a similar manner, the air quality toot in this
Guide does not and cannot replace Clean Air Act Title V permit conditions that may apply to
industrial waste disposal units. The purpose of this Guide is to help industry, state, tribal, and
environmental representatives by providing a wealth of information that relays and defers to
existing legal requirements.
What is the Relationship Between This Guide and Statutory or
Regulatory Provisions?
Please recognize that this is a voluntary guidance document, not a regulation, nor does it
change or substitute for any statutory or regulatory provisions. This document presents techni-
cal information and recommendations based on EPA's current understanding of a range of
issues and circumstances involved in waste management The statutory provisions and EPA reg-
ulations contain legally binding requirements, and to the extent any statute or regulatory provi-
sion is cited in the Guide, it is that provision, not the Guide, which is legally binding and
enforceable. Thus, this Guide does not impose legally binding requirements, nor does it confer
legal rights or impose legal obligations on anyone or implement any statutory or regulatory
provisions. When a reference is made to a RCRA criteria, for example, EPA does not intend to:
convey that any recommended actions, procedures, or steps discussed in connection with the
reference are required to be taken. Those using this Guide are free to use and accept other
technically sound approaches. The Guide contains information and recommendations designed
to be useful and helpful to the public, the regulated community, states/tribes, and local gov-
ernments. The word "should" as used in the Guide is intended solely to recommend particular
action and does not connote a requirements. Similarly, examples are presented as recommenda-
tions or demonstrations, not as requirements. To the extent any product, trade name, or com-
pany appears in the Guide, their mention does not constitute or imply endorsement or recom-
mendation for use by either the U.S. Government or EPA. Interested parties are free to raise
questions and objections about the appropriateness of the application of the examples present-
ed in the Guide to a particular situation.
x.
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Part I
Getting Started
Chapter 1
Understanding Risk and Building Partnerships
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Contents
I. Understanding Risk Assessment 1 - 1
A. Introduction to Risk Assessment 1 - 1
B. Types of Risk 1 -2
C. Assessing Risk 1 - 3
1. Hazard Identification .- '...1 - 5
2. Exposure Assessment: Pathways, Routes, and Estimation ...1 - 5
3. Risk Characterization :-..! - 8
4. Tiers for Assessing Risk .1 - 10
D. Results :1 - 10
II. Information on Environmental Releases 1 - 11
III. Building Partnerships 1 - 11
A. Develop a Partnership Plan 1 - 12
B. Inform the State and Public About New Facilities or Significant
Changes in Facility Operating Plans 1 - 13
C.Make Knowledgeable and Responsible People Available for Sharing Information 1 - 16
D. Provide Information About Facility Operations 1 - 16
Understanding Risk and Building Partnerships Activity List 1 - 19
Resources 1 - 20
Appendix 1 - 22
Tables:
Table 1: Effective Methods for Public Notification ; '. „!- 14
Figures:
Figure 1: Multiple Exposure Pathways/Routes ..1 - 7
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Getting Started—Understanding Risk and Building Partnerships
Understanding Risk and Building Partnerships
This chapter will help you:
• Understand the basic principles of risk assessment and the science
behind it.
• Build partnerships between a company that generates and man-
ages waste, the community within which the company lives and
works, and the state agency that regulates the company in order
to build trust and credibility among all parties.
A. Introduction to Risk
esidents located near waste man-
agement units want to understand
the management activities taking
place in their neighborhoods. They
want to know that waste is being
managed safely, without danger to public
health or the environment. This requires an
understanding of the basic principles of risk
assessment and the science behind it.
Opportunities for dialogue between facilities,
states, tribes, and concerned citizens, includ-
ing a discussion of risk factors, should take
place before decisions are made. Remember,
successful partnerships are an ongoing activity.
i. Understanding
Risk Assessment
Environmental risk communication skills
are critical Co successful partnerships between
companies, state regulators, the public, and
other stakeholders. As more environmental
management decisions are made on the basis
of risk, it is increasingly important for all inter-
ested parties to understand the science behind
risk assessment. Encouraging public participa-
tion in environmental decision-making means
ensuring that all interested parties understand
the basic principles of risk assessment and can
converse equally on the development of
assumptions that underlie the analysis.
Assessment
This Guide provides simple-to-use risk
assessment tools that can assist in determining
the appropriate waste management practices
for surface impoundments, landfills, waste
piles, and land application units. The tools
estimate potential human health impacts from
a waste management unit by modeling two
possible exposure pathways: releases through
volatile air emissions and contaminant migra-
tion into ground water. Although using the
tools is simple, it is still essential to under-
stand the basic concepts of risk assessment to
be able to interpret the results and understand
the nature of any uncertainties associated with
the analysis. This section provides a general
overview of the scientific principles underly-
ing the methods for quantifying cancer and
This chapter will help address the fol-
lowing questions".
« What is risk and how is it assessed?
• What are the benefits of building
partnerships?
• What methods have been successful
in building partnerships?
• What is involved in preparing a
stakeholder meeting?
1-1
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Getting Started—Understanding Risk and Building Partnerships
noncancer risk. Ultimately, understanding the
scientific principles will lead to more effective
use of the provided tools.
B. Types of Risk
Risk is a concept used to describe situa-
tions or circumstances that pose a hazard to
people or things they value. People encounter
a myriad of risks during common everyday
activities, such as driving a car, investing
money, and undergoing certain medical pro-
cedures. By definition, risk is comprised of
two components: die probability that an
adverse event will occur and the magnitude
of the consequences of that adverse event. In
capturing these two components, risk is typi-
cally stated in terms of the probability (e.g.,
one chance in one million) of a specific
harmful "endpoint" (e.g., accident, fatality,
cancer).
In the context of environmental manage-
ment and this section in the Guide, risk is
defined as the probability or likelihood that
public health might be unacceptably impact-
ed from exposure to chemicals contained in
waste management units. The risk endpoints
resulting from the exposure are typically
grouped into two major consequence cate-
gories: cancer risk and noncancer risk.
The cancer risk category captures risks
associated with exposure to chemicals that
might initiate cancer. To determine a cancer
risk, one must calculate the probability of an
individual developing any type of cancer dur-
ing his or her lifetime from exposure to car-
cinogenic hazards. Cancer risk is generally
expressed in scientific notation; in this nota-
tion, the chance of 1 person in 1,000,000 of
developing cancer would be expressed as 1 x
106 or 1E-6.
The noncancer risk category is essentially a
catch-all category for the remaining health
effects resulting from chemical exposure.
Noncancer risk encompasses a diverse set of
effects or endpoints, such as weight loss,
enzyme changes, reproductive and develop-
mental abnormalities, and respiratory reac-
• tions. Noncancer risk is generally assessed by.
comparing the exposure or average intake of a
chemical with a corresponding reference (a
health benchmark), thereby creating a ratio.
The ratio so generated is referred to as the
hazard quotient (HQ). An HQ that is greater
than 1 indicates that the exposure level is
above the protective level of the health bench-
mark, whereas, an HQ less than 1 indicates
that the exposure is below the protective level
established by the health benchmark.
It is important to understand that exposure
to a chemical does not necessarily result in an
adverse health effect. A chemical's ability to
initiate a harmful health effect depends on
the toxicity of the chemical as well as the
route (e.g., ingestion, inhalation) and dose
(the amount that a human intakes) of the
exposure. Health benchmark values are used
to quantify a chemicals possible toxicity and
ability to induce a health effect, and are
derived from toxicity data. They represent a
"dose-response"1 estimate that relates the like-
lihood and severity of adverse health effects
to exposure and dose. The health benchmark
is used in combination with an individual's
exposure level to determine if there is a risk.
Because individual chemicals generate differ-
ent health effects at different doses, bench-
marks are chemical specific; additionally,
since health effects are related to the route of
exposure and the timing of the exposure,
health benchmarks are specific to the route
and the duration (acute, subchronic, or
chronic) of the exposure. The definitions of
acute, subchronic, and chronic exposures
vary, but acute typically implies an exposure
of less than one day, subchronic generally
indicates an exposure of a few weeks to a few
months, and chronic exposure can span peri-
ods of several months to several years.
1 Dose-response is the correlative relationship between the dose of a chemical received by a subject and the
degree of response to that exposure.
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Getting Started—Understanding Risk and Building Partnerships
The health benchmark for carcinogens is
called the cancer slope factor. A cancer slope
factor (CSF) is defined as the upper-bound2
estimate of the probability of a response per
unit intake of a chemical over a lifetime and is
expressed in units of (mg/kg-d). The slope fac-
tor is used to estimate an upper-bound proba-
bility of an individual developing cancer as a
result of a lifetime of exposure to a particular
concentration of a carcinogen.
A reference dose (RfD) for oral exposure
and reference concentration (RfC) for inhala-
tion exposure are used to evaluate noncancer
effects. The RfD and RfC are estimates of daily
exposure levels to individuals (including sen-
sitive populations) that are likely to be with-
out an appreciable risk of deleterious effects
during a lifetime and are expressed in units of
mg/kg-d (RfD) or mg/m3 (RfC).
Most health benchmarks reflect some
degree of uncertainty because of the lack of
precise toxicological information on the peo-
ple who might be most sensitive (e.g., infants,
elderly, nutritionally or immunologically com-
promised) to the effects of hazardous sub-
stances. There is additional uncertainty
because most benchmarks must be based on
studies performed on animals, as relevant
human studies are lacking. From time-to-time
benchmark values are revised to reflect new
toxicology data on a chemical. In addition,
because many states have developed their own
toxicology benchmarks, both the ground-
water and air tools in this Guide enable a user
to input alternative benchmarks to those that
are provided.
There are several sources for obtaining
health benchmarks, some of which are sum-
marized in the text box on the following page.
Most of these sources have toxicological pro-
files and fact sheets on specific chemicals that
are written in a general manner and summa-
rize the potential risks of a chemical and how
it is currently regulated. One good Internet
Example of Health Benchmarks for
Acrylonitrile -
Chronic:
inhalation CSF: 0.24 (mg/kg-d)
oral CSF: 0.54 (mg/kg-d)
RfC 0.002 mg/m3
,RfD: 0.001 mg/kg-d
Subchronic: ""
' RfC-0.02 mg/m3
•• /
Acute:'
- ATSDR MRL: 0.22 mg/m3
source is the Agency for Toxic Substances and
Disease Registry (ATSDR) . ATSDR provides fact sheets for many
chemicals. These fact sheets are easy to under-
stand and provide general information regard-
ing the chemical in question. An example for
cadmium is provided in the appendix at the
end of this chapter. Additional Internet sites
are also available such as: the Integrated Risk
Information System (IRIS); EPAs Office of Air
Quality Planning and Standards Hazardous Air
Pollutants Fact Sheets; EPAs Office of Ground
Water and Drinking Water Contaminant Fact
Sheets; New Jersey's Department of Health,
Right to Know Program's Hazardous Substance
Fact Sheets; Environmental Defense's
Chemical Scorecard; EPAs Office of Pollution
Prevention and Toxics (OPPT) Chemical Fact
Sheets, American Chemistry Council (ACC),
and several others. Visit the Envirofacts
Warehouse Chemical References Complete
Index at for links to
these Web sites.
C. Assessing Risk
Sound risk assessment involves the use of
an organized process of evaluating scientific
data. A risk assessment ultimately serves as
2 Upper-bound is a number that is greater than or equal to any number in a set.
1-3
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Getting Started—Understanding Risk and Building Partnerships
Sources for Health Benchmarks
Integrated Risk Information System (IRIS) The
Integrated Risk Information System (IRIS) is the
Agency's official repository of Agency-wide, consensus,
chronic human health risk information. IRIS contains
Agency consensus scientific positions on potential
adverse human health effects that might result from.
chronic (or lifetime) exposure to environmental contam-
inants. IRIS information, includes the reference dose for
noncancer health effects resulting from oral exposure,
the reference concentration for noncancer health effects
resulting from inhalation exposure, and the carcinogen
assessment for both oral and inhalation exposure. IRIS
can be accessed at .
Health Effects Assessment Summary Tables
(HEAST) HEAST is a comprehensive listing compiled
by EPA consisting of risk assessment information relative
to oral and inhalation routes for chemicals. HEAST
benchmarks are considered secondary to those con-
tained in IRIS. Although the entries in HEAST have
undergone review and have the concurrence of individ-
ual Agency Program Offices, they have either not been
reviewed as extensively as those in IRIS or they do not
have as complete a data set as is required for a chemical
to be listed in IRIS. HEAST can be ordered from NTIS
by calling 1-800-553-IRIS or accessing their Website at
.
Agency for Toxic Substances and Disease Registry
(ATSDR) The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA), requires
that the Agency for Toxic Substances and Disease
Registry (ATSDR) develop jointly with the EPA, in order
of prionty, a list of hazardous substances most common-
ly found at facilities on the CERCLA National Priorities
List, prepare toxicological profiles for each substance
included on the prionty list of hazardous substances;
ascertain significant human exposure levels (SHELs) for
hazardous substances in the environment, and the asso-
ciated acute, subchromc, and chronic health effects; and
assure the initiation of a research program to fill identi-
fied data needs associated with the substances.,The ,
ATSDR Minimal Risk Levels (MRLs) were, developed as
an initial response to the mandate. MRLs are based on
noncancer health effects only and are not based on a
consideration of cancer effects MRLs, are. derived fqr
acute (1-14 days), intermediate (15-364 days);'and -
chronic (365/lays and longer) exposure durations,'for /''
the oral and inhalation routes of exposure. ATSDR's tox-
icological profiles can be accessed at
guidance for making management decisions by
providing one of the inputs to the decision
making process. Risk assessment furnishes ben-
eficial information for a variety of situations,
such as determining the appropriate pollution
control systems for an industrial site, predicting
the appropriateness of different waste manage-
ment options or alternative waste management
unit configurations, or identifying exposures
that might require additional attention.
The risk assessment process involves data
collection activities, such as identifying and
characterizing the source of the environmental
pollutant, determining the transport of the pol-
lutant once it is released into the environment,
determining the pathways of human exposure,
and identifying the extent of exposure for indi-
viduals or populations at risk.
Performing a risk assessment is complex and
requires knowledge in a number of scientific
disciplines. Experts in several areas, such as
toxicology, geochemistry, environmental engi-
neering, and meteorology, can be involved in
performing a risk assessment. For the purpose
of this section, and for brevity, the basic com-
ponents important to consider when assessing
risk are summarized in three main categories
listed below. A more extensive discussion of
these components can be found in the refer-
ences listed at the end of this section. The
three main categories are:
1-4
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Getting Started—Understanding Risk and Building Partnerships
1. Hazard Identification: identifying
and characterizing the source of the
potential risk (e.g., chemicals man-
aged in a waste management unit).
2. Exposure Assessment: determining
the exposure pathways and exposure
routes from the source to an individual:
3. Risk Characterization: integrating
the results of the exposure assess-
ment with information on who is
potentially at risk (e.g., location of
the person, body weights) and chem-
ical toxicity information.
1. Hazard Identification
For the purpose of the Guide, the source
of the potential risk has already been identi-
fied: waste management units. However,
there must be a release of chemicals from a
waste management unit for there to be expo-
sure and risk. Chemicals can be released from
waste management units by a variety of
processes, including volatilization (where
chemicals in vapor phase are released to the
air), leaching to ground water (where chemi-
cals travel through the ground to a ground-
water aquifer), paniculate emission (where
chemicals attached to particulate matter are
released in the air when the particulate mat-
ter becomes airborne), and runoff and ero-
sion (where chemicals in soil water or
attached to" soil particles move to the sur-
rounding area).
To consider these releases in a risk assess-
ment, information characterizing the waste
management"unit is needed. Critical parame-
ters include the size of the unit and its loca-
tion. For example, larger units have the
potential ttrproduce larger releases. Units
located close to the water table might pro-
duce greater releases to ground water than
units located further from the water table.
Units located, in a hot, dry, windy climate can
produce greater volatile releases than units in
a cool, wet, non-windy climate.
2. Exposure Assessment:
Pathways, Routes, and
Estimation
Individuals and populations can come into
contact with environmental pollutants by a
variety of exposure mechanisms and process-
es. The mere presence of a hazard, such as
toxic chemicals in a waste management unit,
does not denote the existence of a risk.
Exposure is the bridge between what is con-
sidered a hazard and what actually presents a
risk. Assessing exposure involves evaluating
the potential or actual pathways for and
extent of human contact with toxic chemi-
cals. The magnitude, frequency, duration, and
route of exposure to a substance must be
considered when collecting all of the data
necessary to construct a complete exposure
assessment.
The steps for performing an exposure
assessment include identifying the potentially
exposed population (receptors); pathways of
exposure; environmental media that transport
the contaminant; contaminant concentration
at a receptor point; and receptors exposure
time, frequency, and duration. In a determin-
istic exposure assessment, single values are
assigned to each exposure variable. For exam-
ple, the length of time a person lives in the
same residence adjacent to the facility might
be assumed to be 30 years. Alternatively, in a
probabilistic analysis, single values can be .
replaced with probability distribution func-
tions that represent the range in real-world
variability, as well as uncertainty. Using the
time in residence example, it might be found
that 10 percent of the people adjacent to the
facility live in their home for less than three
years, 50 percent less than six years, 90 per-
cent less than 20 years, and 99 percent less
than 27 years.
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A probabilistic risk assessment is per-
formed by running the equations that
describe each distribution in a program in
conjunction with a Monte Carlo program.
The Monte Carlo program randomly selects a
value from the designated distribution and
mathematically treats it with numbers ran-
domly selected from distributions for other
parameters. This process is repeated a num-
ber of times (e.g., 10,000 times) to generate a
distribution of theoretical values. The person
assessing risk then uses his or her judgement
to select die risk value (e.g., 50th or 90th
perceritile).
The output of the exposure assessment is a
numerical estimate of exposure and intake of
a chemical by an individual. The intake infor-
mation is then used in concert with chemical-
specific health benchmarks to quantify risks
to human health.
Before gathering these data, it is important
to understand what information is necessary
for conducting an adequate exposure assess-
ment and what type of work might be
required. Exposures are commonly deter-
mined by using mathematical models of
chemical fate and transport to determine
chemical movement in the environment in
conjunction with models of human activity
patterns. The information required for per-
forming the exposure assessment includes
site-specific data such as soil type, meteoro-
logical conditions, ground-water pH, and
location of the nearest receptor. Information
must be gathered for the two components of
exposure assessment: exposure
pathways/routes and exposure quantifica-
tion/estimation.
a. Exposure Pathways/Routes
An exposure pathway is the course the
chemical takes from its source to the individ-
ual or population it reaches. Chemicals cycle
in the environment by crossing through the
different types of media which, are considered
exposure pathways: air, soil, ground water,
surface water, and biota (Figure 1). As a result
of this movement, a chemical can be present
in various environmental media, and human
exposure often results from multiple sources.
The relative importance of an exposure path-
way depends on the concentration of a chemi-
cal in the, relevant medium and the rate of
intake by the exposed individual. In a com-
prehensive risk assessment, the risk assessor
identifies all possible site-specific pathways
through which a chemical could move and
reach a receptor. The Guide provides tools to
model the transport and movement of chemi-
cals through two environmental pathways: air
and ground water.
The transport of a chemical in the environ-
ment is facilitated by natural forces: wind and
water are the primary physical processes for
distributing contaminants. For example,
atmospheric transport is frequently caused by
ambient wind. The direction and speed of the
wind determine where a chemical can be
found. Similarly, chemicals found in surface
water and ground water are carried by water
currents or sediments suspended in the water.
The chemistry of the contaminants and of
the surrounding environment, often referred
to as the "system," also plays a significant role
in determining the ultimate distribution of
pollutants in the various types of media.
Physical-chemical processes, including disso-
lution/precipitation, volatilization, photolytic
and hydrolytic degradation, sorption, and
complexation, can influence the distribution
of chemicals among the different environ-
mental media and the transformation from
one chemical form to another3. An important
component of creating a conceptual model
for performing a risk assessment is the identi-
fication of the relevant processes that occur in
a system. These complex processes depend
on the conditions at the site and specific
chemical properties.
Kolluru, Rao (1996).
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Getting Started—Understanding Risk and Building Partnerships
Figure 1. Multiple Exposure Pathways/Routes (National Research
Council, "Frontiers in Assesssing Human Exposure," 1991)
into another chemical that is solu-
ble and can be excreted.
Some contaminants can also be
absorbed by the skin. The skin is
not very permeable and usually
provides a sufficient barrier against
most chemicals. Some chemicals,
however, can pas's through the
skin in sufficient quantities to
induce severe health effects. An
example is carbon tetrachloride,
which is readily absorbed through
the skin and at certain doses can
cause severe liver damage. The
dermal route is typically consid-
ered in worker scenarios in which
the worker is actually performing
activities that involve skin contact
with the chemical of concern. The
tools provided in the Guide do
not address the dermal route of
exposure.
Whereas the exposure pathway dictates the
means by which a contaminant can reach an
individual, the exposure route is the way in
which that chemical comes in contact with
the body. To generate a health effect, the
chemical must come in contact with the body
In environmental risk assessment, three expo-
sure routes are generally considered: inges-
tion, inhalation, and dermal absorption. As
stated earlier, the toxicity of a chemical is spe-
cific to the dose received and its means of
entry into the body. For example, a chemical
that is inhaled might prove to be toxic and
result in ,a harmful health effect, whereas the
same chemical might cause no reaction if
ingested, or vice-versa. This phenomenon is
due to the differences in physiological
response once a chemical enters the body. A
chemical that is inhaled reaches the lungs and
enters the blood system. A chemical that is
ingested might be metabolized into a different
chemical that might result in a health effect or
b. Exposure Quantification/Estimation
Once appropriate fate-and-transport mod-
eling has been performed for each pathway,
providing an estimate of the concentration of
a chemical at an exposure point, the chemical
intake by a receptor must be quantified.
Quantifying the frequency, magnitude, and
duration of exposures that result from the
transport of a chemical to an exposure point
is critical to the overall assessment. For this
step, the risk assessor calculates the chemical-
specific exposures for each exposure pathway
identified. Exposure estimates are expressed
in terms of the mass of a substance in contact
with the body per unit body weight per unit
time (e.g., milligrams of a chemical per kilo-
gram body weight per day, also expressed as
mg/kg-day).
. The exposure quantification process
involves gathering information in two main
areas: the activity patterns and the biological
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Key Chemical Processes
Sorption: the partitioning of a chemical between the liq-
xiid and solid phase determined by its affinity for adhering
to other solids in the system such as soils and sediment.
The amount of chemical that "sorbs" to solids and does not
move through die environment is dependent upon the
characteristics of the chemical, the characteristics -of the
surrounding soils and sediments, and the quantity of the
chemical. A sorption coefficient is the measure of a. chemi-
cals ability to sorb. If too much of the chemical is present,
the available binding sites on soils and sediments will be
filled and sorption will not continue.
Dissolution/precipitation: the taking in or coming out of
solution by a substance. In dissolution a chemical is taken
into solution; precipitation is the formation of an insoluble
solid. These processes are a function of the nature of the
chemical and its surrounding environment and are depen-
dent on properties such as temperature and pH. A chemical's
solubility is characterized by a solubility product. Chemicals
that tend to volatilize rapidly are not highly soluble.
, Degradation: die break down of a chemical into other
substances in the environment. Some degradation processes:
include biodegradation, hydrolysis, and photolysis. Not:all
degradation products have the same risk as the "parent"
compound. Although most degradation products present
less risk than the parent compound, some chemicals can
break down into "daughter" products that are more harmful
than the parent compound. In performing a risk assessment,,
it is important to consider what the daughter products of
degradation might be.
Bioaccumulation: the take up/ingestion and storage of a
substance into an organism. For substances that bioaccu- ,
mulate, the concentrations of the substance in the organism:;;
can exceed the concentrations in the environment since the
organism will store the substance and not excrete it.
Volatilization: the partitioning of a compound into a ;..
gaseous state. The volatility of a compound is dependent
on its water solubility and vapor pressure. The extent to >; ;
which a chemical can partition into air is described by one
of two constants: Henry's Law or Rauolt's Law. Other fee- :;/
tors that are important to volatility are atmospheric temper-
ature and waste mixing. •
characteristics'Ce.g., body weight, inhalation
rate) of receptors ."Activity patterns and bio-
logical characteristics dictate the amount of a
constituent that a receptor can intake and the
doSe that is received per kilogram of body
weight. Chemical intake values are calculated
using equations-that include variables for
exposure concentration, contact rate, exposure
frequency, exposure duration, body weight,
and exposure averaging time. The values of
some of these variables depend on the site
conditions and the characteristics of the
potentially exposed population. For example,
the rate of oral ingestion of contaminated food
is different for different subgroups of recep-
tors, which might include adults, children,
area visitors, subsistence farmers, and subsis-
tence fishers. Children typically drink greater
quantities of milk each day than adults per
unit body weight. A subsistence fisher would
be at a greater risk than another area resident
from the ingestion of contaminated fish. ',
Additionally, a child might have a greater rate
of soil ingestion than an adult due to playing
outdoors or hand-to-mouth behavior patterns.
The activities of individuals also determine the
duration of exposure. A resident might live in
the area for 20 years and be in the area for
more than 350 days each year. Conversely, a
visitor or a worker will have shorter exposure
times. After the intake values have been esti-
mated, they should be organized by popula-
tion as appropriate (e.g., children, adult
residents) so that the results in the risk char-
acterization can be reported for each popula-
tion group. To the extent feasible, site-specific
values should be used for estimating the expo-
sures; otherwise, default values suggested by
the EPA in The Exposure Factors Handbook
(EPA, 1995) can be used. .
3. Risk Characterization
In the risk-characterization process, the
health benchmark information (i.e., cancer
slope factors, reference doses, reference concen-
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Getting Started—Understanding Risk and Building Partnerships
trations) and the results of the exposure assess-
ment (estimated intake or dose by potentially
exposed populations) are integrated to arrive at
quantitative estimates of cancer and noncancer
risks. To characterize the potential noncarcino-
genic effects, comparisons are made between
projected intake levels of substances and refer-
ence dose or reference concentration values. To
characterize potential carcinogenic effects,
probabilities that an individual will develop
cancer over a lifetime are estimated from pro-
jected intake levels and the chemical-specific
cancer slope factor value. This procedure is the
final calculation step. This step determines who
is likely to be affected and what the likely
effects are. Because of all the assumptions
inherent in calculating a risk, a risk characteri-
zation cannot be considered complete unless
the numerical expressions of risk are accompa-
nied by explanatory text interpreting and quali-
fying the results. As shown in the text box, the
risk characterization step is different for car-
cinogens and noncarcinogens.
Calculating Risk
Cancer Risks:
Incremental risk of cancer = average
daily dose (mg/kg-day) *• slope factor
, (mg/kg-day) ' " .,
Non-Cancer Risks:
Hazard quotient = exposure or intake
(mg/kg-day) or (mg/m3)/ RfD (mg/kg-
day) or RfC (mg/m3)
Another consideration during the risk-
characterization phase is the cumulative
effects of multiple exposures. A given popula-
tion can be exposed to multiple chemicals
from several exposure routes and sources.
Multiple constituents might be managed in a
single waste management unit, for example,
and by considering one chemical at a time,
the risks associated with the waste manage-
ment unit might be underestimated. The EPA
has developed guidance outlined in the Risk
Assessment Guidance for Superjund, Volume I
(U.S. EPA, 1989b) to assess the overall poten-
tial for cancer and noncancer effects posed by
multiple chemicals. The risk assessor, facility
manager, and other interested parties should
determine the appropriateness of adding the
risk contribution of each chemical for each
pathway to calculate a cumulative cancer risk
or noncancer risk. The procedures for adding
risks differ for carcinogenic and noncarcino-
genic effects.
The cancer-risk equation described in the
adjacent box estimates the incremental indi-
vidual lifetime cancer risk for simultaneous
exposure to several carcinogens and is based
on EPA (1989a) guidance. The equation com-
bines risks by summing the risks to a recep-
tor from each of the carcinogenic chemicals.
Cancer Risk Equation for
Multiple Substances
Riskr = SRisk,"*" '-
where:
RiskT = the total cancer risk,
expressed as a unitless probability.
SRisk, = the sum of the risk estimates „
for all of the chemical risks.
Assessing cumulative effects from noncar-
cinogens is more difficult and contains a
greater amount of uncertainty than an assess-
ment for carcinogens. As discussed earlier,
noncarcinogenic risk covers a diverse set of
health effects and different chemicals will
have different effects. To assess the overall
potential for noncarcinogenic effects posed by
more than one chemical, EPA developed a
hazard index (HI) approach. The approach
assumes that the magnitude of an adverse
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Getting Started—Understanding Risk and Building Partnerships
health effect is proportional to the sum of the
hazard quotients of each of the chemicals
investigated. In keeping with EPAs Risk
Assessment Guidance, hazard quotients should
only be added for chemicals that have the
same critical effect (e.g., both chemicals affect
the liver or both initiate respiratory distress).
As a result, an extensive knowledge of toxi-
cology is needed to sum the hazard quotients
to produce a hazard index. Segregation of
hazard indices by effect and mechanism of
action can be complex, time-consuming, and
will have some degree of uncertainty associat-
ed with it. This analysis is not simple and
should be performed by a lexicologist.
4. Tiers for Assessing Risk
As part of the Guide, EPA has used a 3-
tiered approach for assessing risk associated
with air and water releases from waste man-
agement units. Under this approach, an
acceptable level of protection is provided
across all tiers, but with each progressive'tier
the level of uncertainty in the risk analysis is
reduced. Reducing the level of uncertainty in
the risk analysis might reduce the level of
control required by a waste management unit
(if appropriate for the site), while maintaining
an acceptable level of protection. The facility
performing the risk assessment accepts the
higher costs associated with a more complex
risk assessment in return for greater certainty
and potentially reduced construction and
operating costs.
The advantages and relative costs of each
tier are outlined below.
Tier 1 Evaluation
• Allows for a rapid but conservative
assessment.
• Lower cost.
• Requires minimal site data.
• Contaminant fate-and-transport and
exposure assumptions are developed
using conservative, non-site specific
assumptions provided by EPA. The
values are provided in "look-up
tables" that serve as a quick and
straightforward means for assessing
risk. These values are calculated to be
protective over a broad range of con-
ditions and situations and are by
design very conservative.
Tier 2 Evaluation
• Represents a higher level of complex-
ity.
• Moderate cost.
• Provides the ability to input some
site-specific data into the risk assessT
ment and thus provides a more accu-
rate representation of site risk.
• Uses relatively simplistic fate and
transport models.
Tier 3 Evaluation
• Provides a sophisticated risk assess-
ment.
• Higher cost.
• Provides the maximum use of site-
specific data and thus provides the
most accurate representation of site
risk.
• Uses more complex fate-and-trans-
port models and analyses.
D. Results
The results of a risk assessment provide a
basis for making decisions but are only one
element of input into the process of designing
a waste management unit. The risk assess-
ment does not constitute the only basis for
management action. Other factors are also
important, such as technical feasibility of
options, public values, and economics.
Understanding and interpreting the results
for the purpose of making decisions also
requires a thorough knowledge of the
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Getting Started—Understanding Risk and Building Partnerships
assumptions that were applied during the
risk assessment. Ample documentation
should be assembled to describe the scenarios
that were evaluated for the risk assessment
and any uncertainty associated with the esti-
mate. Information that should be considered
for inclusion in the risk assessment documen-
tation include: a description of the contami-
nants that were evaluated; a description of
the risks that are present (i.e., cancer, non-
cancer); the level of confidence in the infor-
mation used in the assessment; the major
factors driving the site risks; and the charac-
teristics of the exposed population. The
results of a risk assessment are essentially
meaningless without the information on how
they were generated.
II, Information on
Environmental
Releases
There are several available sources of infor-
mation that citizens can review to understand
chemical risk better and to review potential
environmental release from waste manage-
ment units in their communities. The
Emergency Planning and Community Right-
to-Know Act (EPCRA) of 1986 provides one
such resource. EPCRA created the Toxic
Release Inventory (TRI) reporting program
which requires facilities in designated
Standard Industry Codes (see 40 CFR
§372.22) with more than 10 employees that
manufacture or process more than 25,000
pounds, or otherwise use more than 10,000
pounds, of a TRI- listed chemical to report
their environmental releases annually to EPA
and state governments. Environmental releas-
es include the disposal of wastes in landfills,
surface impoundments, land application
units, and waste piles. EPA compiles these
data in the TRI database and release this
information to the public annually. Facility
operators might wish to include TRI data in
the facility's information repository. TRI data,
however, are merely raw data. When estimat-
ing risk, other considerations need to be
examined and understood too, such as the
nature and characteristics of the specific facil-
ity and surrounding community.
In 1999, EPA promulgated a final rule that
established alternate thresholds for several
persistent, bioaccumulative, and toxic (PBT)
chemicals (see 64 FR 58665; October 29,
1999). In this rule, EPA has added seven
chemicals to the EPCRA Section 313 list of
TRI chemicals and lowered the reporting
thresholds for another 18 PBT chemicals and
chemical categories. For these 18 chemicals,
the alternate thresholds are significantly lower
than the standard reporting thresholds of
25,000 pounds manufactured or processed,
and 10,000 pounds otherwise used.
EPCRA is based on the belief that citizens
have a right to know about potential environ-
mental risks caused by facility operations in
their communities, including those posed as a
result of waste management. TRI data, there-
fore, provide yet another way for residents to
learn about the waste management activities
taking place in their neighborhood and to
take a more active role in decisions that
potentially affect their health and environ-
ment. More information on TRI and access to
TRI data can be obtained from EPAs Web site
.
HI. Building
Partnerships
Building partnerships between all stake-
holders—the community, the facility, and the
regulators—can provide benefits to all par-
ties, such as:
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• Better understanding of waste man-
agement activities at an industrial
facility.
• Better understanding of facility, state,
and community issues.
• Greater support of industry proce-
dures and state policies.
• Reduced delays and costs associated
with opposition and litigation.
• A positive image for a company and
relationship with the state and com-
munity.
Regardless of the size or type of a facility's
waste management unit, facilities, states, and
local communities can all' follow similar prin-
ciples in the process of building partnerships.
These principles are described in various
state public involvement guidance docu-
ments, various EPA publications, and state
requirements for waste facilities. These prin-
ciples embody sound business practices and
common sense and can go beyond state
requirements that call for public participation
during the issuance of a permit. The Guide
recommends principles that can be adopted
throughout the operating life of a facility, not
just during the permitting process. Following
these principles will help all involved consid-
er the full range of activities possible to give
partners an active voice in the decision-mak-
ing process, and in so doing, will result in a
positive working relationship.
A. Develop a Partnership
Plan
The key to effective involvement is good
planning. Developing a plan for how and
when to involve all parties in making deci-
sions will help make partnership activities run
smoothly and achieve the best results.
Developing a partnership plan also helps iden-
tify concerns and determine which involve-
ment activities best
address those con-
cerns.
The first step in
developing a part-
nership plan is to
work with the state
agency to under-
stand what involve-
ment requirements
exist. Existing state
requirements deal-
ing with partnership plans must be followed.
(Internet sites for all state environmental'
agencies are available from .) After this step, you should
assess the level of community interest gener-
ated by a facility's waste management activi-
ties. Several criteria influence the amount of
public interest, including implications for ., •
public health and welfare, current relation-
ships between the facility and community
members, and the community's political and
economic climate. Even if a facility has not
generated much public interest in the past,
involving the public is a good idea. Interest
in a facility can increase suddenly when
changes to existing activities are proposed or
when residents' attitudes and a community's
political or economic climate change.
To gauge public interest in a facility's waste
management activities and to identify the
community's major concerns, facility repre-
sentatives should conduct interviews with
community members. They can first talk
with members of community groups, such as
civic leagues, religious organizations, and
business associations. If interest in the facili-
ty's waste management activities seems high,
facility representatives can consider conduct-
ing a more comprehensive set of community
interviews. Other individuals to interview
include the facility's immediate neighbors,
representatives from other.agencies and envi-
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Getting Started—Understanding Risk and Building Partnerships
ronmental organizations, and any individuals
in the community who have expressed inter-
est in the facility's operations.
Using the information gathered during the
interviews, facility representatives can devel-
op a list of the community's concerns regard-
ing the facility's waste management activities.
They can then begin to engage the communi-
ty in discussions about how to address those
concerns. These discussions can form the
basis of a partnership plan.
B. Inform the State and
Public About New
Facilities or Significant
Changes in Facility
Operating Plans
A facility's decision to change its opera-
tions provides a valuable opportunity for
involvement. Notifying the state and public
of new units and proposed changes at exist-
ing facilities gives these groups the opportu-
nity to identify applicable state requirements
and comment on matters that apply to them.
What are examples of effective
methods for notifying the public?
Table 1 presents examples of effective
methods for public notification and associat-
ed advantages and disadvantages. The
method used at a particular facility, and
within a particular community, will depend
on the type of information or issues that
need to be communicated and addressed.
public notices usually provide the name and
address of the facility representative and a
brief description of the change being consid-
ered. After a public notice is issued, a facility
can develop informative fact sheets to
explain proposed changes in more detail.
Fact sheets and public, notices can include
the name and telephone number of a contact
person who is available within the facility to
answer questions.
What is involved in preparing a
meeting with industry, community,
and state representatives?
Meetings can be an effective means of giv-
ing and receiving comments and addressing
concerns. To publicize a meeting, the date,
time, and location of the meeting should be
placed in a local newspaper and/or advertised
on the radio. To help ensure a successful dia-
logue, meetings should be at times conve-
nient for members of the community, such as
early in the evenings during the week, or on
weekends. An interpreter might need to be
obtained if the local community includes resi-
dents whose primary language is not English.
Prior to a meeting, the facility representa-
tive should develop a waste management plan
or come to the meeting prepared to describe
how the industrial waste from the facility will
be managed. A waste management plan pro-
vides a starting point for public comment and
input. Keep data presentations simple and
provide information relevant to the audience.
Public speakers should be able to respond to
both general and technical questions. Also,
the facility representative should review and
be familiar with the concerns of groups or cit-
izens who have
previously
expressed an
interest in the
facility's opera-
tions. In addi-
tion, it is
important to
anticipate ques-
tions and plan
how best to
respond to these
questions at a
meeting.
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Table 1
Effective Methods for Public Notification
I fylelhod^ Features "/V;;^ '' Advantages • .Disadvantages •!
Briefings
Mailing of key
technical reports or
environmental
documents
News conferences
Newsletters
Newspaper inserts
Paid advertisements
News releases
Presentations to civic
and technical groups
Press kits
Advisory groups and
task forces
Personal visit or phone call to
key officials or group leaders to
announce a decision, provide
background information, or
answer questions.
Mailing technical studies or
environmental reports to other
agencies, leaders of organized
groups, or other interested parties
Brief presentation to reporters,
followed by a question-and-
answer period, often
accompanied by handouts of
presenter's comments.
Brief description of what is going
on, usually issued at key intervals
for all people who have shown
interest.
Much like a newsletter, but
distributed as an insert in a
newspaper.
Advertising space purchased in
newspapers or on the radio or
television.
A short announcement or news
story issued to the media to get
interest in media coverage ofthe
story.
Deliver presentations, enhanced
with slides or overheads, to key
community groups.
A packet of information
distributed to reporters.
A group of representatives of key
nterested parties is established.
Possibly a policy, technical, or
citizen advisory group.
Provides background information.
Determines reactions before an issue
"goes public." Alerts key people to
issues that might affect them.
Provides full and detailed information
to people who are most interested.
Often increases the credibility of
studies because they are fully visible.
Stimulates media interest in a story.
Direct quotations often appear in
television and radio. Might draw
attention to an announcement or
generate interest in public meetings.
Provides more information than can
be presented through the media to
those who are most interested. Often
used to provide information prior to
public meetings or key decision points.
Helps to maintain visibility during
extended technical studies.
Reaches the entire community with
important information. Is one of the
few mechanisms for reaching everyone
in the community through which you
can tell the story your way.
Effective for announcing meetings or
key decisions or as background
material for future media stories.
Might stimulate interest from the
media. Useful for announcing
meetings or major decisions or as
background material for future media
stories.
Stimulates communication with key
community groups. Can also provide
in-depth responses.
Stimulates media interest in the story
Provides background information that
reporters can use for future stories.
Promotes communication between
key constituencies. Anticipates public
reaction to publications or decisions.
Provides a forum for reaching
consensus.
Requires time.
Costs money to print and
mail. Some people might not
read the reports.
Reporters will only come if
the announcement or presen-
tation is newsworthy. Cannot
control how the story is pre-
sented, although some direct
quotations are likely.
Requires staff time. Costs
money to prepare, print, and
mail. Stories must be objec-
tive and credible, or people
will react to the newsletters
as if diey were propaganda.
Requires staff time to prepare
the insert, and distribution
costs money. Must be pre-
pared to newspapers layout
specifications.
Advertising space can be
costly Radio and television
can entail expensive produc-
tion costs to prepare the ad.
Might be ignored or not
read. Cannot control how
the information is used.
Few disadvantages, except
some groups can be hostile.
Few disadvantages, except
cannot control how the
information is used and
might not be read.
Potential for controversy
exists if "advisory" recom-
mendations are not followed.
Requires substantial commit-
ment of staff time to provide
support to committees.
1-14
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Getting Started—Understanding Risk and Building Partnerships
Table 1
Effective Methods for Public Notification (cont.)
Methods V: : Features ' „ ,.-./--" Advantages - -; "• , ; -Disadvantages i.
Focus groups
Telephone line
Meetings
Small discussion groups
established to give "typical"
reactions of the public.
Conducted by a professional
facilitator. Several sessions can be
conducted with different groups.
Widely advertised phone number
that handles questions or provides
centralized source of information.
Less formal meetings for people
to present positions, ask'
questions, and so forth.
Provides in-depth reaction to ideas or
decisions. Good for predicting
emotional reactions
Gives people a sense that they know
whom to call. Provides a one-step
service of information. Can handle
two-way communication.
Highly legitimate forum for the public
to be heard on issues. Can be
structured to permit small group
interaction — anyone can speak.
Gets reactions, but no
knowledge of how many
people share those reactions.
Might be perceived as an
effort to manipulate the
public.
Is only as effective as the
person answering the tele-
, phone. Can be expensive.
Unless a small-group discus-
sion format is used, it permits
only limited dialogue. Can
get exaggerated positions or
grandstanding. Requires staff
time to prepare for meetings.
U.S. EPA 1990. Sites for Our Solid Waste; A Guidebook for Effective Public Involvement.
State representatives also should antici-
pate and be prepared to answer questions
raised during the meeting. State representa-
tives should be prepared to answer ques-
tions on specific regulatory or compliance
issues, as well as to address how the facility
has been working in cooperation with the
state agency. The following are some ques-
tions that are often asked at meetings.
• What are the risks to me associated
- with the operations?
• Who should I contact at the facility if
I have a question or concern?
• How will having the facility nearby
benefit the area?
•• Will there be any noticeable day-to-
day effects on the community?
• Which processes, generate industrial
waste, and what types of waste are
generated?
• How will the waste streams be treat-
ed or managed?
• What are the construction plans for
any proposed containment facilities?
• What are the intended methods for
monitoring and detecting emissions
or potential releases?
• What are the plans to address acci-
dental releases of chemicals or wastes
at the site?
• What are the plans for financial
assurance, closure, and post-closure
care?
• What are the applicable state' regula-
tions?
• How long will it take to issue the
permit?
• How will the .permit be issued?
• Who should I contact at the state •
agency if I have questions or con-
cerns about the facility?
At the meeting, the,facility representative •
should invite public and state comments on .
the proposed change(s), and tell community
1-15
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Getting Started—Understanding Risk and Building Partnerships
members where, and to whom, they should
send written comments. A facility can choose
to respond to comments in several ways. For
example, telephone calls, additional fact
sheets, or additional meetings can all be used
to address comments. Responding promptly
to residents' comments and concerns demon-
strates an honest attempt to addres.s them.
one-to-one. Similarly, workshops and briefin-
gs enable community members, state officials,
and facility representatives to interact, ask
questions, and learn about the activities at the
facility. Web sites can also serve as a useful
tool for facility, state, and community repre-
sentatives to share information and ask ques-
tions.
C Make Knowledgeable
and Responsible People
Available for Sharing
Information
Having a facility representative available to
answer the public's questions and provide
information helps assure citizens that the
facility is actively listening to their concerns.
Having a state contact available to address the
publics concerns about the facility can also
make sure that concerns are being heard and
addressed.
In addition to 'identifying a contact person,
facilities and states should consider setting up
a telephone line staffed by employees for citi-
zens to call and obtain information promptly
about the facility. Opportunities for face-to-
face interaction between community mem-
bers and facility representatives include onsite
information offices, open houses, workshops,
or briefings.
Information
offices function
similarly to infor-
mation reposito-
ries, except that
an employee is
present to answer
questions. Open
houses are infor-
mal meetings on
site where resi-
dents can talk to
company officials
D. Provide Information
About Facility
Operations
Providing information about facility opera-
tions is an invaluable way to help the public
understand waste management activities.
Methods of informing communities include
conducting facility tours; maintaining a pub-
licly accessible information repository on site
or at a convenient offsite public building such
as a library; developing exhibits to explain
operations; and distributing information
through the publications of established orga-
nizations. Examples of public involvement
activities are presented in the following pages.
Conduct facility tours. Scheduled facility
tours allow community members and state
representatives to visit the facility and ask
questions about how it operates. By seeing a
facility first-hand, residents learn how waste
is managed and can become more confident
that it is being managed safely. Individual cit-
izens, local officials, interest groups, students,
and the media might want to take advantage
of facility tours. In planning tours, determine
the maximum number of people that can be
taken through the facility safely and think of
ways to involve tour participants in what they
are seeing, such as providing hands-on
demonstrations. It is also a good idea to have
facility representatives available to answer
technical questions in an easy-to-understand
manner.
1-16
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Getting Started—Understanding Risk and Building Partnerships
Maintain a publicly accessible informa-
tion repository. An information repository is
simply a collection of documents describing
the facility and its activities. It can include
background information on the facility, the
partnership plan (if developed), permits to
manage waste on site, fact sheets, and copies
of relevant guidance and regulations. The
repository should be in a convenient, publicly
accessible place. Repositories are often main-
tained on site in a public "reading room" or
off site at a public library, town hall, or public
health office. Facilities should publicize the
existence, location, and hours of the reposito-
ry and update the information regularly.
Develop exhibits that explain facility
operations. Exhibits are visual displays, such
as maps, charts, diagrams, or photographs,
accompanied by brief text. They can provide
technical information in an easily under-
standable way and an opportunity to illus-
trate creatively and informatively issues of
concern. When developing exhibits, identify
the target audience, clarify which issue or
aspect of the facility's operations will be the
exhibits focus, and determine where the
exhibit will be displayed. Public libraries,
convention halls, community events, and
shopping centers are all good, highly visible
locations for an exhibit.
Use publications and mailing lists of
established local organizations. Existing
groups and publications often provide access
to established communication networks. Take
advantage of these networks to minimize the
time and expense required to develop mailing
lists and organize meetings. Civic or environ-
mental groups, rotary clubs, religious organi-
zations, and local trade associations might
have regular meetings, newsletters, newspa-
pers, magazines, or mailing lists that could be
useful in reaching interested members of the
community.
1-17
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Getting Started—Understanding Risk and Building Partnerships
American Chemistry Council's
Responsible Care®
To address citizens' concerns about the manu-.
facture, transport, use, and disposal of chemical
products, the American Chemistry Council (ACC)
launched its Responsible Care® program in 1988.
To maintain their membership in ACC, companies
must participate in the Responsible Care® pro-
gram. One of the key components of the program
is recognizing and responding to community con-
cerns about chemicals and facility operations.
ACC member are committed to fostering an
open dialogue with residents of the communities in
which they are located. To do dais, member compa-
nies are required to address community concerns m
two ways: (1) by developing and maintaining com-'
munity outreach programs, and (2)..by assuring that
each facility has an emergency resporise program in
place. For example, member companies provide
information about their waste minimization and
emissions reduction activities, as well as provide
convenient ways for citizens to become familiar
widi the facility, such as tours. Many companies
also set up Community Advisory Panels. These
panels provide a mechanism for dialogue on issues
between plants and local communides. Companies
must also develop written emergency response
plans that include information about how to com-
municate with members of the public and consider
their needs after an emergency.
Responsible Care® is just one example of how
public involvement principles can be incorporated
into everyday business practices. The program also
shows how involving the public makes good busi-
ness sense. For more information about
Responsible Care®, contact ACC at 703 741-5000
AF&PA's Sustainable Forestry
Initiative
Public concern about the future of America's
forests coupled with die American Forest & Paper
Association's (AE&PAs) belief ..that "sound environ-
mental policy and sound business practice go hand
in hand" fueled the establishment of the
Sustainable Forestry Initiative (SFI). Established in
19957 the SFI outlines principles and objectives for
environmental stewardship with which all AF&PA
members must comply in order to retain member-
ship. SFI encourages protecting wildlife habitat
and water quality, reforesting harvested land, and
conserving ecologically sensitive forest land. SFI
recognizes that continuous public involvement is
crucial to its ultimate goal of "ensuring that future
generations of Americans will have the same abun-
dant forests that we enjoy today."
X
The SFI stresses the importance of reaching out
to the public through toll-free information lines,
^environmental education, private and public sector
technical"assistance programs, workshops, videos,
and other means. To help keep the public
informed of achievements in sustainable forestry,
members report annually on* their progress, and
AF&PA distributes the resulting publication to
interested parties. In addition, AF&PA runs two
national forums a year, which bring together log-
gers, Jandowners, andjjenior industry representa-
tives to Review progress toward SFI objectives.
Many AF&PA state chapters have developed
additional activities to inform the public about the
SFL'For example, in New Hampshire, AF&PA
'published a brochure about sustainable forestry
and used it to brief local sawmill officials and die
media. In Vermont, a 2-hour interactive television
'session^allowed representatives from industry, pub-
lic agencies', environmental organizations; the aca- '
demic community, and private citizens to share
their,views on sustainable-forestry Furthermore, in
West Virginia, AF&PA formed a Woodland Owner'
Education Committee to reach, out to nonindustrial
private Jandowners. >
For more information about the SFI, contact
AF&PA at 800 878-8878, or visit the Web site'
.
1-18
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Getting Started—Understanding Risk and Building Partnerships
Understanding Risk and Building
Partnerships Activity List
You should consider the following activities in understanding risk and building partnerships between
facilities, states, and community members when addressing potential waste management practices.
D Understand the definition of risk.
D Review sources for obtaining health benchmarks.
D Understand the risk assessment process including the pathways and routes of potential exposure
and how to quantify or estimate exposure.
D Be familiar with the risk assessment process for cancer risks and non-cancer risks.
D Develop exhibits that provide a better understanding of facility operations.
D Identify potentially interested/affected people.
D Notify the state and public about new facilities or significant changes in facility operating plans.
D Set up a public meeting for input from the community.
D Provide interpreters for public meetings.
D Make knowledgeable and responsible people available for sharing information.
D Develop a partnership plan based on information gathered in previous steps.
D Provide tours of the facility and information about its operations.
D Maintain a publicly accessible information repository or onsite reading room.
D Develop environmental risk communication skills.
1-19
-------
Getting Started—Understanding Risk and Building Partnerships
Resources
American Chemistry Council. 2001 Guide to Community Advisory Panels.
American Chemistry Council. Revised 2001. Environmental Justice and Your Community: A Plant
Manager's Introduction.
American Chemistry Council. Responsible Care® Overview Brochure.
Council in Health and Environmental Science, ENVIRON Corporation. 1986. Elements of Toxicology
and Chemical Risk Assessment.
Executive Order 12898. 1994. Federal Actions to Address Environmental Justice in Minority
Populations and Low-income Populations. February.
Holland, C.D., and R.S. Sielken, Jr. 1993. Quantitative Cancer Modeling and Risk Assessment.
Kolluru, Rao, Steven Bartell, et al. 1996. Risk Assessment and Management Handbook: For
Environmental, Healdi, and Safety Professionals.
Louisiana Department of Environmental Quality. 1994. Final Report to the Louisiana Legislature on
Environmental Justice.
Lu, Frank C. 1996. Basic Toxicology: Fundamentals, Target Organs, and Risk Assessment.
National Research Council. 1983. Risk Assessment in the Federal Government: Managing the Process.
Public Participation and Accountability Subcommittee of the National Environmental Justice Advisory
Council (A Federal Advisory Committee to the U.S. EPA). 1996. The Model Plan for Public
Participation. November.
Texas Natural Resource Conservation Commission. 1993. Texas Environmental Equity and Justice Task
Force Report: Recommendations to the Texas Natural Resource Conservation Commission.
Travis, C.C. 1988. Carcinogenic Risk Assessment.
U.S. EPA. 1996a. RCRA Public Involvement Manual. EPA530-R-96-007.
1-20
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Getting Started—Understanding Bisk and" Building Partnerships
Resources (cent.)
U.S. EPA. 1996b. 1994 Toxics Release Inventory: Public Data Release, Executive Summary. EPA745-S-
96-001.
U.S. EPA. 1995a. Decision-maker's Guide to Solid Waste Management, Second Edition. EPA530-R-95-
023.
U.S. EPA. 1995b. The Exposure Factors Handbook. EPA600-P-95-002A-E. . , .
U.S. EPA. 1995c. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.
U.S. EPA. 1992. Environmental Equity: Reducing Risk for all Communities. EPA230-R-92-008A.
U.S. EPA. 1990. Sites for our Solid Waste: A Guidebook for Effective Public Involvement. EPA530-
SW-90-019.
U.S. EPA. 1989a. Chemical Releases and Chemical Risks: A Citizen's Guide to Risk Screening. EPA560-
2-89-003.
U.S. EPA. 1989b. Risk Assessment Guidance for Superfund. EPA540-1-89-002.
U.S. Government Accounting Office. 1995. Hazardous and Nonhazardous Waste: Demographics of
People Living Near Waste Facilities. GAO/RCED-95-84.
Ward, R. 1995. Environmental Justice in Louisiana: An Overview of the Louisiana Department of
Environmental Quality's Environmental Justice Program.
Western Center for Environmental Decision-Making. 1996. Public Involvement in Comparative Risk
Projects: Principles and Best Practices: A Source Book for Project Managers.
1-21
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Getting Started—Understanding Risk and Building Partnerships
Appendix
=ATSDR
CADMIUM
CAS # 7440-43-9
Agency fpr Toxic Substances and Disease'Registry ToxFAQs
June, 1999
This fact sheet answers the most frequently asked health questions (FAQs) about cadmium. For more information,
call the ATSDR Information Center at 1-SSS-422-S737. This fact sheet is one in a series of summaries about
hazardous substances and their health effects. It's important you understand this information because this
substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration,
how you are exposed, personal traits and habits, and whether other chemicals are present
HIGHLIGHTS: Exposure to cadmium happens mostly in the workplace where
cadmium products are made. The general population is exposed from breathing
cigarette smoke or eating cadmium contaminated foods. Cadmium damages the
lungs, can cause kidney disease, and may irritate the digestive tract. This substance
has been found hi at least 776 of the 1,467 National Priorities List sites identified.'
by the Environmental Protection AgencylEPA)}' ^,f,,.s
What is cadmium?
(Pronounced kad'mg-am)
Cadmium is a natural element in the earth's crust. It is
usually found as a mineral combined with other elements such
as oxygen (cadmium oxide), chlorine (cadmium chloride), or
sulfur (cadmium sulfate, cadmium sulfide).
All soils and rocks, including coal and mineral fertilizers,
contain some cadmium. Most cadmium used in the United
States is extracted during the production of other metals like
zinc, lead, and copper. Cadmium does not corrode easily and
has many uses, including batteries, pigments, metal coatings,
and plastics.
What happens to cadmium when it enters the
environment?
q Cadmium enters air from mining, industry, and burning
coal and household wastes.
q Cadmium particles in air can travel long distances before
falling to the ground or water.
q It enters water and soil from waste disposal and spills or
leaks at hazardous waste sites.
q It binds strongly to soil particles.
q Some cadmium dissolves in water.
q It doesn't break down in the environment, but can change
forms.
q Fish, plants, and animals take up cadmium from the envi- ,
ronment.
q Cadmium stays in the body a very long time and can
build up from many years of exposure to low levels.
How might I be exposed to cadmium?
q Breathing contaminated workplace air (battery manufac-
turing, metal soldering or welding).
q Eating foods containing it; low levels in all foods (high-
est in shellfish, liver, and kidney meats).
q Breathing cadmium in cigarette smoke (doubles the aver-
age daily intake).
q Drinking contaminated water.
q Breathing contaminated air near the burning of fossil
fuels or municipal waste.
How can cadmium affect my health?
Breathing high levels of cadmium severely damages the
lungs and can cause death. Eating food or drinking water with
very high levels severely irritates the stomach, leading to
vomiting and diarrhea. Long-term exposure to lower levels of
cadmium in air, food, or water leads to a buildup of cadmium
in the kidneys and possible kidney disease.
US. DEPARTMENT OF HEALTH AND HUMAN SERVICES, Public Health Service
1 Agency for Tojfic Substances and Disease Registry '
1-22
-------
Getting Started—Understanding Risk and Building Partnerships
Page 2
CADMIUM
CAS # 7740-43-9
ToxFAQs Internet address via WWW is http://www.atsdr.cdc.gov/toxfaq.htnil
Other long-term effects are lung damage and fragile
bones. Animals given cadmium in food or water had high
blood pressure, iron-poor blood, liver disease, and nerve or
brain damage.
We don't know if humans get any of these diseases from
eating or drinking cadmium. Skin contact with cadmium is not
known to cause health effects in humans or animals.
How likely is cadmium to cause cancer?
The Department of Health and Human Services (DHHS) has
determined that cadmium and cadmium compounds may rea-
sonably be anticipated to be carcinogens.
How can cadmium affect children?
The health effects in children are expected to be similar to
those in adults (kidney, lung and intestinal damage).
We don't know if cadmium causes birth defects in people.
Cadmium does not readily go from a pregnant woman's body
into the developing child, but some portion can cross the pla-
centa. It can also be found in breast milk. The babies of ani-
mals exposed to high levels of cadmium during pregnancy had
changes in behavior and learning ability. Cadmium may also
affect birth weight and the skeleton in developing animals.
Animal studies also indicate that more cadmium is ab-
sorbed into the body if the diet is low in calcium, protein, or
iron, or is high in fat. A few studies show that younger animals
absorb more cadmium and are more likely to lose bone and
bone strength than adults.
How can families reduce the risk of exposure to
cadmium?
In the home, store substances that contain cadmium safely,
and keep nickel-cadmium batteries out of reach of young
children. If you work with cadmium, use all safety precautions
to avoid carrying cadmium-containing dust home from work
on your clothing, skin, hah", or tools.
A balanced diet can reduce the amount of cadmium taken
into the body from food and drink.
Is there a medical test to show whether I've been
exposed to cadmium?
Tests are available in some medical laboratories that mea-
sure cadmium in blood, urine, hair, or nails. Blood levels
show recent exposure to cadmium, and urine levels show both
recent and earlier exposure. The reliability of tests for cad-
mium levels in hair or nails is unknown.
Has the federal government made
recommendations to protect human health?
The EPA has set a limit of 5 parts of cadmium per billion
parts of drinking water (5 ppb). EPA doesn't allow cadmium in
pesticides.
The Food and Drug Administration (FDA) limits the
amount of cadmium in food colors to 15 parts per million
(ISppm).
The Occupational Safety and Health Administration
(OSHA) limits workplace air to 100 micrograms cadmium per
cubic meter (100 ug/m3) as cadmium fumes and 200 fig cad-
mium/m3 as cadmium dust,
Source of Information
Agency for Toxic Substances and Disease Registry
(ATSDR). 1999. Toxicological profile for cadmium. Atlanta,
GA: U.S. Department of Health and Human Services, Public
Health Service.
Where can I get more information? For more information, contact the Agency for Toxic Substances and Disease
Registry, Division of Toxicology, 1600 Clifton Road NE, Mailstop E-29, Atlanta, GA 30333. Phone: 1-888-422-8737,
FAX: 404-639-6359. ToxFAQs Internet address via WWW is http://www.atsdr.cdc.gov/toxfaq.html ATSDR can tell you
where to find occupational and environmental health clinics. Their specialists can recognize, evaluate, and treat illnesses
resulting from exposure to hazardous substances. You can also contact your community or state health or environmental
quality department if you have any more questions or concerns.
Federal Recycling Program
Printed on Recycled Paper
1-23
-------
-------
Part I
Getting Started
Chapter 2
Characterizing Waste
-------
Contents
I. Waste Characterization Through Process Knowledge 2 - 2
II. Waste Characterization Through Leachate Testing 2 - 3
A. Sampling and Analysis Plan 2 - 4
1. Representative Waste Sampling , 2 - 6
2. Representative Waste Analysis 2 - 8
B. Leachate Test Selection 2 - 9
1. Toxicity Characteristic Leaching Procedure (TCLP) 2 - 10
2. Synthetic Precipitation Leaching Procedure (SPLP) 2 - 11
3. Multiple Extraction Procedure (MEP) 2 - 12
4. Shake Extraction of Solid Waste with Water or Neutral Leaching Procedure 2 - 13
III. Waste Characterization of Volatile Organic Emissions 2 - 13
Waste Characterization Activity List 2 -15
Resources 2 - 16
Appendix 2 - 18
-------
Getting Started—-Characterizing Waste
Characterizing Waste
This chapter will help you:
• Understand the industrial processes that generate a waste.
• Determine the waste's physical and chemical properties.
• Estimate constituent leaching to facilitate ground-water risk analysis.
• Quantify total constituent concentrations to facilitate air emissions
analysis.
Understanding the physical and
chemical properties of a waste
using sampling and analysis
techniques is the cornerstone
upon which subsequent steps in
the Guide are built. It is necessary for gauging
what risks a waste might pose to surface water,
ground water, and air and drives waste man-
agement unit design and operating decisions.
Knowing the composition of the waste is also
necessary when determining the constituents
for which to test. And, as discussed in Chapter
3—Integrating Pollution Prevention, knowledge
of the physical and chemical properties of the
waste is crucial in identifying pollution pre-
vention opportunities.
In many instances, you can use knowledge
of waste generation processes, analytical test-
This chapter will help you address the
following questions: ^
• How can process knowledge be used
to characterize a waste?
.• Which constituent concentrations
should be quantified?:
• Which type of leachate test should; be
used?
ing, or some combination of the two to esti-
mate waste generation rates and waste con-
stituent concentrations. To the extent that the
waste is not highly variable, the use of process
knowledge can be a sound approach to waste
characterization and can prove more reason-
able and cost effective than frequent sampling
of the waste. It is important to note, however,
that owners or operators using process knowl-
edge to characterize a waste in lieu of testing
are still responsible for the accuracy of their
determinations. No matter what approach is
used in characterizing a waste, the goal is to
maximize the available knowledge that is nec-
essary to make the important decisions
described in later chapters of the Guide. Also,
as changes are made to the industrial process-
es or waste management practices, it might be
necessary to recharacterize a waste in- order to
accurately make waste management decisions
and evaluate risk.
In considering the use of process knowl-
edge or analytical testing, it is important to
note that the ground water and air emissions
models that accompany the Guide use con-
stituent concentrations to estimate risk. Input
requires specific concentrations which cannot
be precisely estimated solely by knowledge of
the processes that generate the waste. Further,
when wastes are placed in a waste manage-
ment unit, such as a landfill or surface
2-1
-------
Getting Started—Characterizing Waste
impoundment, they are subjected to various
physical, chemical, and biological processes
that can result in the creation of new com-
pounds in the waste, changes in the mass and
volume of the waste, and the creation of dif-
ferent phases within the waste and within the
landfill or impoundment. In order to accu-
rately predict the concentration of the conta-
minants in the leachate, these changes must
be accounted for.
Accurate waste management unit con-
stituent characterization is also necessary for
input to the modeling tools provided in the
Guide. Because model input requires specific
data, model output will be based on the accu-
racy of the data input. Process knowledge
alone (unless based on previous testing) might
not be sufficiently accurate to yield reliable
results. Leachate testing (discussed later in
this chapter), for example, will likely give you
a more precise assessment of waste con-
stituent concentrations than process knowl-
edge. Also note that whether you are using
process knowledge, testing, or a combination
of both, sources of model input data must be
well documented so that an individual evalu-
ating the modeling results understands the
background supporting the assessment.
I. Waste
Characterization
Through Process
Knowledge
A waste characterization begins with an
understanding of the industrial processes that
generate a waste. You must obtain enough
information about the process to enable
proper characterization of the waste, for
example, by reviewing process flow diagrams
or plans and determining all inputs and out-
puts. You should also be familiar with other
waste characteristics such as the physical
state of the waste, the volume of waste pro-
duced, and the general composition of the
waste. In addition, many industries have
thoroughly tested and characterized their
wastes over time, therefore it might be benefi-
cial to contact your trade association to deter-
mine if waste characterizations have already
been performed and are available for process-
es similar to yours. Additional resources can
assist in waste characterization by providing
information on waste constituents and poten-
tial concentrations. Some examples include:
• Chemical engineering designs or
plans for the process, showing
process input chemicals, expected
primary and secondary chemical
reactions, and products.
• Material Safety Data Sheets (MSDSs)
for materials involved. (Note that not
all MSDSs contain information on all
constituents found in a product.)
• Manufacturer's literature.
• Previous waste analyses.
• Literature on similar processes. :
• Preliminary testing results, if available.
A material balance exercise using process :
knowledge can be useful in understanding
where wastes are generated within a process
and in estimating concentrations of waste con-
stituents particularly where analytical test data
2-2
-------
Getting Started—-Characterizing Waste
are limited. In a material balance, all input
streams, such as raw materials fed into the
processes, and all output streams, such as
products produced and waste generated, are
calculated. Flow diagrams can be used to iden-
tify important process steps and sources where
wastes are generated. Characterizing wastes
using material balances can require consider-
able effort and expense, but can help you to
develop a more complete picture of the waste
generation process(es) involved.
Note that a thorough assessment of your
production processes can also serve as the
starting point for facility-wide waste reduc-
tion, recycling, or pollution prevention
efforts. Such an assessment will provide the
information base to explore many opportuni-
ties to reduce or recycle the volume or toxici-
ty of wastes. Refer to Chapter 3-Integrating
Pollution Prevention for ideas, tools, and ref-
erences on how to proceed.
While the use of process knowledge is
attractive because of the cost savings associat-
ed with using existing information, you must
ensure that this information accurately char-
acterizes your wastes. If using process
descriptions, published data, and document-
ed studies to determine waste characteristics,
the data should be scrutinized carefully to
determine if there are any differences between
the processes in the studies and the waste
generating process at your facility, that the
studies are acceptable and accurate (i.e.,
based on valid sampling and analytical tech-
niques), and that the information is current.
If there are discrepancies, or if you begin a
new process or change any of the existing
processes at your facility (so that the docu-
mented studies and published data are no
longer applicable), you are encouraged to
consider performing additional sampling and
laboratory analysis to accurately characterize
the waste and ensure proper management.
Also, if process knowledge is used in addition
What is process ,
knowledge?
Process knowledge refers to detailed
information oh processes that generate
wastes. It can be used to partly, or in
many cases completely, characterize
waste to ensure proper management.
Process knowledge includes:
• Existing published or documented
waste analysis data or studies co'n-
^ ducted on wastes generated by
processes similar to that which gener-
ated the "waste.
• Waste analysis data obtained from
other facilities in'the same industry.
' • Facility's records of previously per-
'- formed analyses.
to, or in place of, sampling and analysis, you
should clearly document the information
used in your characterization assessment to
demonstrate to regulatory agencies, the pub-
lic, and other interested parties that the infor-
mation accurately and completely
characterizes the waste. The source of this
information should be clearly documented.
81. Waste
Characterization
Through
Leachate Testing
Although sampling and laboratory analysis
is not as economical and might not be as
convenient as using process knowledge, it
does have advantages. The resulting data usu-
ally provide the most accurate information
available on constituent concentration levels.
2-3
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Getting Started—Characterizing Waste
Incomplete or mis-characterization of waste
can lead to improper waste management, inac-
curate modeling outputs, or erroneous deci-
sions concerning the type of unit to be used,
liner selection, or choice of land application
methods. Note that process knowledge allows
you to eliminate unnecessary or redundant
waste testing by helping you focus, on which
constituents to measure in the waste. Again,
thorough documentation of both the process
knowledge used (e.g., studies, published data),
as well as the analytical data is important.
The intent of leachate and extraction testing
is to estimate the leaching potential of con-
stituents of concern to water sources. It is
important to estimate leaching potential in
order to accurately estimate the quantity of
chemicals that could potentially reach ground-
or surface-water resources (e.g., drinking
water supply wells, waters used for recre-
ation). The Industrial Waste Management
Evaluation Model (IWEM) developed for the
Guide uses expected leachate concentrations
for the waste management units as the basis
for liner system design recommendations.
Leachate tests will allow you to accurately
quantify the input terms for modeling.
If the total concentration of all the con-
stituents in a waste has been estimated using
process knowledge (which could include pre-
vious testing data on wastes known to be very
similar), estimates of the maximum possible
concentration of these constituents in leachate
can be made using the dilution ratio of the
leachate test to be performed.
For example, the Toxicity Characteristic
Leachate Procedure (TCLP) allows for a total
constituent analysis in lieu of performing the
test for some wastes. If a waste is 100 percent
solid, as defined by the TCLP method, then
the results of the total compositional analysis
may be divided by twenty to convert the total
results into the maximum leachable concentra-
tion1. This factor is derived from the 20:1 liq-
uid to solid ratio employed in the TCLE This
is a conservative approach to estimating
leachate concentrations and does not factor in
environmental influences, such as rainfall. If a
waste has filterable liquid, then the concentra-
tion of each phase (liquid and solid) must be
determined. The following equation may be
used to calculate this value:2
CVjXQ) + (V2)(C2)
20V2
Where:
Vj = Volume of the first phase (L)
Q = Concentration of the analyte of con-
cern in the first phase (mg/L)
V2 = Volume of the second phase (L)
C2 = Concentration of the analyte of con-
cern in the second phase (mg/L)
Because this is only a screening method for
identifying an upper-bound TCLP leachate
concentration, you should consult with your
state or local regulatory agency to determine
whether process knowledge can be used to
accurately estimate maximum risk in lieu of
leachate testing.
A. Sampling and Analysis
Plan
One of the more critical elements in proper
waste characterization is the plan for sampling
and analyzing the waste. The sampling plan is
usually a written document that describes the
objectives and details of the individual tasks of
2-4
This method is only appropriate for estimating maximum constituent concentration in leachate for non-
liquid wastes (e.g., those wastes not discharged to a surface impoundment). For surface impoundments,
the influent concentration of heavy metals can be assumed to be the maximum theoretical concentration
of metals in the leachate for purposes of input to the ground-water modeling tool that accompanies this
document. To estimate the leachate concentration of organic constituents in liquid wastes for modeling
input, you will need to account for losses occurring within the surface impoundment before you can esti-
mate the concentration in the leachate (i.e., an.effluent concentration must be determined for organics).
Source: Office of Solid Waste Web site at .
-------
Getting Started—Characterizing Waste
a sampling effort and how they will be per-
formed. This plan should be carefully thought
out, well in advance of sampling. The more
detailed the sampling plan, the less opportu-
nity for error or misunderstanding during
sampling, analysis, and data interpretation.
To ensure that the sampling plan is
designed properly, a wide range of personnel
should be consulted. It is important that the
following individuals are involved in the
development of the sampling plan to ensure
that the results of the sampling effort are pre-
cise and accurate enough to properly charac-
terize the waste:
• An engineer who understands the
manufacturing processes.
• An experienced member of the sam-
pling team.
• The end user of the data.
• A senior analytical chemist.
• ' A statistician.
• A quality assurance representative.
It is also advisable that you consult the
analytical laboratory to be used when devel-
oping your sampling plan.
Background information on the processes
that generate the waste and the type and
characteristics of the waste management unit
is essential for developing a sound sampling
plan. Knowledge of die unit location and sit-
uation (e.g., geology, exposure of the waste to
the elements, local climatic conditions) will
assist in determining correct sample size and
sampling method. Sampling plan design will
depend]on whether you are sampling a waste
prior to disposal in a waste management unit
or whether you are sampling waste from an-
existing ;unit. When obtaining samples from
an existing unit, care should be taken to
avoid endangering the individuals collecting
the samples and to prevent damaging the unit
itself. Reasons for obtaining samples from an
existing unit include, characterizing the waste
in the unit to determine if the new waste
being added is compatible, checking to see if
the composition of the waste is changing over
time due to various chemical and biological
breakdown processes, or characterizing the
waste in the unit or the leachate from the
unit to give an indication of expected concen-
trations in leachate from a new unit.
The sampling plan must be correctly
defined and organized in order to get an
accurate estimation of the characteristics of
the waste. Both an appropriate sample size
and proper sampling techniques are neces-
sary. If the sampling process is carried out
correctly, the sample will be representative
and the estimates it generates will be useful
for making decisions concerning proper man-
agement of the waste and for assessing risk.
In developing a sampling plan, accuracy is
of primary concern. The goal of sampling is to
get an accurate estimate of the wastes charac-
teristics from measuring the sample's charac-
teristics. The main controlling factor in
deciding whether the estimates will be accu-
rate is how representative the sample is (dis-
cussed in the following section). Using a small
sample increases the possibility that the sam-
ple will not be representative, but a sample
that is larger than the minimum calculated
sample size does not necessarily increase the
probability of getting a representative sample.
As you are developing the sampling plan, you
should address the following considerations:
• Data quality objectives.
• Determination of a representative
sample.
•. Statistical methods to be employed in
the analyses.
• Waste generation and handling
processes.
2-5
-------
Getting Started—Characterizing Waste
• Constituents/parameters to be sampled.
• Physical and chemical properties of
the waste.
• Accessibility of the unit.
• Sampling equipment, methods, and
sample containers.
• Quality assurance and quality control
(e.g., sample preservation and han-
dling requirements).
• Chain-of-custody.
• Health and safety of employees.
Many of these considerations are discussed
below. Additional information on data quality
objectives and quality assurance and quality
control can be found in Test Methods for
Evaluating Solid Waste, Physical/Chemical
Methods—SW-846 (U.S. EPA, 1996e), Guidance
for the Data Quality Objectives Process (U.S.
EPA, 1996b), Guidance on Quality Assurance
Project Plans (U.S. EPA, 1998a), and Guidance
for the Data Quality Assessment: Practical
Methods for Data Analysis (U.S. EPA, 1996a).3
A determination as to the constituents that
will be measured can be based on process
knowledge to narrow the focus and expense
of performing the analyses. Analyses should
be performed for those constituents that are
reasonably expected to be in the waste at
detectable levels (i.e., test method detection
levels). Note diat the Industrial Waste
Management Evaluation Model (IWEM) that
accompanies this document recommends
liner system designs, if necessary, or the
appropriateness of land application based on
calculated protective leachate thresholds
(Leachate Concentration Threshold Values or
LCTVs) for various constituents that are like-
ly to be found in industrial waste and pose
hazards at certain levels to people and the
environment. The constituents that are evalu-
ated are listed in Table 1.2 of the Industrial
Waste Management Evaluation Model Technical
Background Document (U.S.. EPA 2002). The
LCTV tables also are included in the IWEM
Technical Background Document and the model
on the CD-ROM version of this Guide, and
can be used as a starting point to help you
determine which constituents to measure. It
is not recommended that you sample for all
of the organic chemicals and metals listed in
the tables, but rather use these tables as a
guide in conjunction with knowledge con-
cerning the waste generating practices to
determine which constituents to measure.
1. Representative Waste
Sampling
The first step in any analytical testing
process is to obtain a sample that is represen-
tative of the physical and chemical composi-
tion of a waste. The term "representative
sample" is commonly used to denote a sample
that has the same properties and composition
in the same proportions as the population
from which it was collected. Finding one sam-
ple which is representative of the entire waste
can be difficult unless you are dealing with a
homogenous waste. Because most industrial
wastes are not homogeneous, many different
factors should be considered in obtaining
samples. Examples of some of the factors that
should be considered include:
• Physical state of the waste. The
physical state of the waste affects
most aspects of a sampling effort. The
sampling device will vary according
to whether the sample is liquid, solid,
gas, or multiphasic. It will also vary
according to whether the liquid is
viscous or free-flowing, or whether
the solid is hard, soft, powdery,
monolithic, or clay-like.
• Composition of the waste. The
samples should represent the average
concentration and variability of the
waste in time or over space.
2-6
These and other EPA publications can be found at the National Environmental Publications Internet
site (NEP1S) at .
-------
Getting Started—Characterizing Waste
• Waste generation and han-
dling processes. Processes to
consider include: if the waste
is generated in batches; if
there is a change in the raw
materials used in a manufac-
turing process; if waste com-
position can vary substantially
as a function of process tem-
peratures or pressures; and if
storage time affects the wastes
characteristics/composition.
• Transitory events. Start-up,
shut-down, slow-down, and
maintenance transients can
result in the generation of a
waste that is not representative
. of the normal waste stream. If
a sample was unknowingly
collected at one of these inter-
vals, incorrect conclusions
could be drawn.
You should consult with your state or
local regulatory agency to identify any
legal requirements or preferences before
initiating sampling efforts. Refer to
Chapter 9 of the EPA's SW-846 test
methods document (see side bar) for
detailed guidance on planning, imple-
menting, and assessing sampling events.
To ensure that the chemical infor-
mation obtained from waste sampling
efforts is accurate, it must be unbiased
and sufficiently precise. Accuracy is
usually achieved by incorporating
some form of randomness into the
sample selection process and by select-
ing an appropriate number of samples.
Since most industrial wastes are het-
erogeneous in terms of their chemical
properties, unbiased samples and
appropriate precision can usually be
achieved by simple random sampling.
In this type of sampling, all units in
the population (essentially all locations
More information on Test Methods
for Evaluating Solid Waste, Physical/
Chemical Methods-SW-846
EPA has begun replacing requirements mandat-
ing the use of specific measurement methods or
technologies with a performance-based measure-
ment system (PBMS). The goal of PBMS-is to
reduce regulatory burden and foster the use of
innovative and emerging technologies or medi-
.odsi.The PBMS:estabhshes what needs to be
accomplished, but does not prescribe specifically
how to do it. In a sampling situation, for exam-
ple, PBMS would establish the data needs, the
level of uncertainty acceptable for making deci-
sions,'and the required supporting documenta-
tion, a specific^ test method would not be
prescribed. This approachlallows the analyst the
flexibility to select the most appropriate and cost
effective fest methods or technologies to comply
with the criteria. Under PBMS, the analyst is
/ required to demonstrate the accuracy of the mea-
surement methodising the specific matrix that is
being analyzed. SW-846'serves only as a guidance
document and starting point for determining
which test method to .use.
SW-846 provides state-of-the-art analytical test
methods for a wide array of inorganic and organic
constituents, as well as procedures for field and
laboratory quality control, sampling, and charac-
teristics testing. The methods are intended to pro-
mote accuracy, sensitivity, specificity, precision,
and comparability of analyses and test results.
For assistance widi the mediods described in SW-
846, call the EPA Method Information
Communication, Exchange (MICE) Hotline at 703"
676-4690 or send an e-mail to mice@cpmxsaic com.
The text of,SW-846 is available online at:
. A hard copy
or CD-ROM version of SW-846 can be purchased
by calling the National Technical Information
Service (NTIS) at 800 553-6847.
2-7
-------
Getting Started—Characterizing Waste
or points in all batches of waste from which a
sample could be collected) are identified, and
a suitable number of samples is randomly
selected from the population.
The appropriate number of samples to
employ in a waste characterization is at least
the minimum number of samples required to
generate a precise estimate of the true mean
concentration of a chemical contaminant in a
waste. A number of mathematical formulas
exist for determining the appropriate number
of samples depending on the statistical preci-
sion required. Further information on sam-
pling designs and methods for calculating
required sample sizes and optimal distribu-
tion of samples can be found in Gilbert
(1987), Winer (1971), and Cochran (1977)
and Chapter 9 of EPA SW-846.
The type of sampling plan developed will
vary depending on the sampling location.
Solid wastes contained in a landfill or waste
pile can be best sampled using a three-
dimensional random sampling strategy. This
involves establishing an imaginary three-
dimensional grid or sampling points in the
waste and then using random-number tables
or random-number generators to select points
for sampling. Hollow-stem augers combined
with split-spoon samplers are frequently
appropriate for sampling landfills.
If the distribution of waste components is
known or assumed for liquid or semi-solid
wastes in surface impoundments, then a two-
dimensional simple random sampling strategy
might be appropriate. In this strategy, the top
surface of the waste is divided into an imagi-
nary grid and grid sections are selected using
random-number tables or random-number
generators. Each selected grid point is then
sampled in a vertical manner along the entire
length from top to bottom using a sampling
device such as a weighted bottle, a drum
thief, or Coliwasa.
If sampling is restricted, the sampling strat-
" egy should, at a minimum, take sufficient
samples to address the potential vertical varia-
tions in the waste in order to be considered
representative. This is because contained
wastes tend to display vertical, rather than
horizontal, non-random heterogeneity due to
settling or the layering of solids and denser
liquid phases. Also, care should be taken
when performing representative sampling of a
landfill, waste pile, or surface impoundment
to minimize any potential to create hazardous
conditions. (It is possible that the improper
use of intrusive sampling techniques, such as
the use of augers, could accelerate leaching by
creating pathways or tunnels that can acceler-
ate leachate movement to ground water.)
To facilitate characterization efforts, consult
with state and local regulatory agencies and a
qualified professional to select a sampling plan
and determine the appropriate number of sam-
ples, before beginning sampling efforts. You
should also consider conducting a detailed
waste-stream specific characterization so that
the information can be used to conduct waste
reduction and waste minimization activities.
Additional information concerning sam-
pling plans, strategies, methods, equipment,
and sampling quality assurance and quality
control is available in Chapters 9 and 10 of the
SW-846 test methods document. Electronic
versions of these chapters have been included
on the CD-ROM version of die Guide.
2. Representative Waste Analysis
After a representative sample has been col-
lected, it must be properly preserved to main-
tain the physical and chemical properties that
it possessed at the time of collection. Sample
types, sample containers, container prepara-
tion, and sample preservation methods are
critical for maintaining the integrity of the
sample and obtaining accurate results.
Preservation and holding times are also
2-8
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Getting Started—Characterizing Waste
important factors to consider and will vary
depending on the type of constituents being
measured (e.g., VOCs, heavy metals, hydro-
carbons) and the waste matrix (e.g., solid,
liquid, semi-solid).
The analytical chemist then develops an
analytical plan which is appropriate for the
sample to be analyzed, the constituents to be
analyzed, and the end use of the information
required. The laboratory should have standard
operating procedures available for review for
the various types of analyses to be performed
and for all associated methods needed to com-
plete each analysis, such as instrument main-
tenance procedures, sample handling
procedures, and sample documentation proce-
dures. In addition, the laboratory should have
a laboratory quality assurance/quality control
statement available for review which includes
all key personnel qualifications.
The SW-846 document contains informa-
tion on analytical plans and methods.
Another useful source of information regard-
ing the selection of analytical methods and
quality assurance/quality control procedures
for various compounds is the Office of Solid
Waste Methods Team home page at
.
B. Leachate Test Selection
Leaching tests are used to estimate poten-
tial concentration or amount of waste con-
stituents that can leach from a waste to
ground water. Typical leaching tests use a
specified leaching fluid mixed with the solid
portion of a waste for a specified time. Solids
are then separated from the leaching solution
and the solution is tested for waste con-
stituent concentrations. The type of leaching
test performed can vary depending on the
chemical, biological, and physical characteris-
tics of the waste; the environment in which
the waste will be placed; as well as the rec-
ommendations or requirements of your state
and local regulatory agencies.
When selecting the most appropriate ana-
lytical tests, consider at a minimum the phys-
ical state of the sample, the constituents to be
analyzed, detection limits, and the specified
holding times of the analytical methods.4 It
might not be cost-effective or useful to con-
duct a test with detection limits at or greater
than the constituent concentrations in a
waste. Process knowledge can help you pre-
dict whether the concentrations of certain
constituents are likely to fall below the detec-
tion limits for anticipated methods.
After assessing the state of the waste, assess
the environment of the waste management
unit in which the waste will be placed. For
example, an acidic environment might
require a different test than a non-acidic envi-
ronment in order to best reflect the condi-
tions under which the waste will actually
leach. If the waste management unit is a
monofill, then the characteristics of the waste
will determine most of the unit's conditions.
Conversely, if many different wastes are being
co-disposed, then the conditions created by
Which leaching test is
appropriate?
Selecting an appropriate leachate test
can be summarized in the following four
steps: , * „ '
1. Assess the physical stateTof the waste
using process knowledge. ,-•
2. Assess the environment in which the
waste will be placed.
3. Consult with your state and/or local
regulatory agency.
4. Select an appropriate leachate test
based on the above information.
There are several general categories of phases in which samples can be categorized: solids, aqueous,
sludges, multiphase samples, ground water, and oil and organic liquid. You should select a test that is
designed for the specific sample type.
2-9
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Getting Started—Characterizing Waste
the co-disposed wastes must be considered,
including the constituents that can be leached
by the subject waste.
A qualified laboratory should always be used
when conducting analytical testing. The labora-
tory can be in-house or independent. When
using independent laboratories, ensure that
they are qualified and competent to' perform
the required tests. Some laboratories might be
proficient in one test but not another. You
should consult with the laboratory before final-
izing your test selection to make certain mat
the test can be performed. When using analyti-
cal tests that are not frequently performed,
additional quality assurance and quality control
practices might need to be implemented to
ensure that the tests are conducted correctly
and diat the results are accurate.
A brief summary of the TCLP and three
other commonly used leachate tests is provid-
ed below (procedures for the EPA test meth-
ods are included in SW-846 and for the
ASTM method in the Annual Book ofASTM
Standards). These summaries are provided as
background and are not meant to imply that
these are the only tests that can be used to
accurately predict leachate potential. Other
leachate tests have been developed and might
be suitable for testing your waste. The table
in the appendix at the end of this chapter
provides a summary of over 20 leachate tests
that have been designed to estimate the
potential for contaminant release, including
several developed by ASTM.5 You should con-
sult with state and local regulatory agencies
and/or a laboratory that is familiar with
leachate testing methods to identify the most
appropriate test and test method procedures
for your waste and sample type.
1. Toxidty Characteristic Leaching
Procedure (TCLP)
The TCLP6 is the test method used to deter-.
mine whether a waste is hazardous due to its
characteristics as defined in the Resource
Conservation and Recovery Act (RCRA), 40
CFR Part 261. The TCLP estimates the teacha-
bility of certain toxicity characteristic hazardous
constituents from solid waste under a defined
set of laboratory conditions. It evaluates the
leaching of metals, volatile and semi-volatile
organic compounds, and pesticides from
wastes. The TCLP was developed to simulate
the leaching of constituents into ground water
under conditions found in municipal solid
waste (MSW) landfills. The TCLP does not sim-
ulate the release of contaminants to non-ground
water pathways. The TCLP is most commonly
used by EPA, state, and local agencies to classify
waste. It is also used to determine compliance
with some land disposal restrictions (LDRs) for
hazardous wastes. The TCLP can be found as
EPA Method 1311 in SW-846.7 A copy of
Method 1311 has been included on the CD-
ROM version of the Guide.
For liquid wastes, (i.e., those containing
less than 0.5 percent dry solid material) the
waste after filtration through a glass fiber fil-
2-10
5 EPA has only reviewed and evaluated those test methods found in SW-846. The EPA has not reviewed
or evaluated the other test methods and cannot recommend use of any test methods other than those
found in SW-846.
6 EPA is undertaking a review of the TCLP test and how it is used to evaluate waste leaching (described
in the Phase IV Land Disposal Restrictions rulemaking, 62 Federal Register 25997; May 26, 1998). EPA
anticipates that this review will examine the effects of a number of factors on leaching and on
approaches to estimating the likely leaching of a waste in the environment. These factors include pH,
liquid to solid ratios, matrix effects and physical form of the waste, effects of non-hazardous salts on
the leachability of hazardous metal salts, and others. The effects of these factors on leaching might or
might not be well reflected in the leaching tests currently available. At the conclusion of the TCLP
review, EPA is likely to issue revisions to this guidance that reflect a more complete understanding of
waste constituent leaching under a variety of management conditions.
7 The TCLP was developed to replace the Extraction Procedure Toxicity Test method which is designated
as EPA Method 1310 in SW-846.
-------
Getting Started—Characterizing Waste
ter is defined as the TCLP extractant. The
concentrations of constituents in the liquid
extract are then determined.
For wastes containing greater than or equal
to 0.5 percent solids, the liquid, if any, is sep-
arated from the solid phase and stored for
later analysis. The solids must then be
reduced to particle size, if necessary. The
solids are extracted with an acetate buffer
solution. A liquid-to-solid ratio of 20:1 by
weight is used for an extraction period of 18
± 2 hours. After extraction, the solids are fil-
tered from the liquid through a glass fiber fil-
ter and the. liquid extract is combined with
any original liquid fraction of the wastes.
Analyses'are then conducted on the liquid fil-
trate/leachate to determine the constituent
concentrations.
To determine if a waste is hazardous
because it exhibits the toxicity characteristic
(TC), the TCLP method is used to generate
leachate under controlled conditions as dis-
cussed above. If the TCLP liquid extract con-
tains any of the constituents listed in Table 1
of 40 CFR Part 261 at a concentration equal
to or greater than the respective value in the
table, the waste is considered to be a TC haz-
ardous waste, unless exempted or excluded
under Part 261. Although die TCLP test was
designed tocdetermine if a waste is hazardous,
the importance of its use for waste characteri-
zation as discussed in this chapter is to
understand"the parameters to be considered
in properly .managing the wastes.
You should check with state and local reg-
ulatory agencies to determine whether the
TCLP is likely to be the best test for evaluat-
ing the leaching potential of a waste or if
another test might better predict leaching
under the anticipated waste management
conditions. Because the test was developed by
EPA to determine if a waste is hazardous
(according to 40 CFR 261.24) and focused
on simulating leaching of solid wastes placed
in a municipal landfill, this test might not be
appropriate for your waste because the leach-
ing potential for the same chemical can be
quite different depending on a number of fac-
tors. These factors include the characteristics
of the leaching fluid, the form of the chemical
in the solids, the waste matrix, and the dis-
posal conditions.
Although the TCLP is die most commonly
used leachate test for estimating the actual
leaching potential of wastes, you should not
automatically default to it in all situations or
conditions and for all types of wastes. While
the TCLP test might be conservative under
some conditions (i.e., overestimates leaching
potential), it might underestimate leaching
under other extreme conditions. In a landfill
that has primarily alkaline conditions, the
TCLP is not likely to be the optimal method
because the TCLP is designed to replicate
leaching in an acidic environment. For mate-
rials that pose their greatest hazard when
exposed to alkaline conditions (e.g., metals
such as arsenic and antimony), use of the
TCLP might underestimate the leaching
potential. When the conditions of your waste
management unit are very different from the
conditions that the TCLP test simulates,
another test might be more appropriate.
Further, the TCLP might not be appropriate
for analyzing oily wastes. Oil phases can be
difficult to separate (e.g., it might be impossi-
ble to separate solids from oil), oily material
can obstruct the filter (often resulting in an
underestimation of constituents in the
leachate), and oily materials can yield both
oil and aqueous leachate which must be ana-
lyzed separately.8
2. Synthetic Precipitation
Leaching Procedure (SPLP)
The SPLP (designated as EPA Method 1312
in SW-846) is currently used by several state
agencies to evaluate the leaching of con-
SW-846 specifies several procedures that should be followed when analyzing oily wastes.
2-11
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Getting Started—Characterizing Waste
stituents from wastes. The SPLP was designed
to estimate the teachability of both organic
and inorganic analytes present in liquids, soils,
and wastes. The SPLP was originally designed
to assess how clean a soil was under EPA's
Clean Closure Program. Even though the fed-
eral hazardous waste program, did not adopt
it for use, the test can still estimate releases
from wastes placed in a landfill and subject to
acid rain. There might be, however, important
differences between soil as a constituent
matrix (for which the SPLP is primarily used)
and the matrix of a generated industrial waste.
A copy of Method 1312 has been included on
the CD-ROM version of the Guide.
The SPLP is very similar to the TCLP
Method 1311. Waste samples containing
solids and liquids are handled by separating
the liquids from the solid phase, and then
reducing solids to particle size. The solids are
then extracted with a dilute sulfuric
acid/nitric acid solution. A liquid-to-solid
ratio of 20:1 by weight is used for an extrac-
tion period of 18±2 hours. After extraction,
the solids are filtered from the liquid extract
and the liquid extract is combined with any
original liquid fraction of the wastes.
Analyses are then conducted on the liquid fil-
trate/leachate to determine the constituent
concentrations.
The sulfuric acid/nitric acid extraction
solution used in the SPLP was selected to
simulate leachate generation, in part, from
acid rain. Also note that in both the SPLP
and TCLP, some paint and oily wastes might
clog the filters used to separate the liquid
extract from the solids prior to analysis,
resulting in under reporting of the extractable
constituent concentrations.
3. Multiple Extraction Procedure
(MEP)
The MEP (designated as EPA Method 1320
in SW-846) was designed to simulate the
leaching that a waste will undergo from repeti-
tive precipitation of acid rain on a landfill .to
determine the highest concentration of each
constituent that is likely to leach in a real,
world environment. Currently, the MEP is used
in EPA's hazardous waste delisting program. A
copy of Method 1320 has been included on
the CD-ROM version of the Guide.
The MEP can be used to evaluate liquid,
solid, and multiphase samples. Waste sam-
ples are extracted according to the Extraction
Procedure (EP) Toxicity Test (Method 1310
of SW-846). The EP test is also very similar
to the TCLP Method 1311. A copy of Method
1310 has been included on the CD- ROM
version of the Guide.
In the MEP, liquid wastes are filtered
through a glass fiber filter prior to testing.
Waste samples containing both solids and liq-
uids are handled by separating the liquids
from the solid phase, and then reducing the
solids to particle size. The solids are then
extracted using an acetic acid solution. A liq-
uid- to-solid ratio of 16:1 by weight is used
for an extraction period of 24 hours. After
extraction, the solids are filtered from the liq-
uid extract, and the liquid extract is combined
with any original liquid fraction of the waste.
The solids portion of the sample that
remains after application of Method 1310 are
then re-extracted using a dilute sulfuric
acid/nitric acid solution. As in the SPLP, this
acidic solution was selected to simulate
2-12
-------
Getting Started—Characterizing Waste
leachate generation, in part, from acid rain.
This time a liquid-to-solid ratio of 20:1 by
weight is used for an extraction period of 24
hours. After extraction, the solids are once
again filtered from the liquid extract, and the
liquid extract is combined with any original
liquid fraction of the waste.
These four steps are repeated eight addi-
tional times. If the concentration of any con-
stituent of concern increases from the 7th or
8th extraction to the 9th extraction, the pro-
cedure is repeated until these concentrations
decrease.
The MEP is intended to simulate 1,000
years of freeze and thaw cycles and prolonged
exposure to a leaching medium. One advan-
tage of the MEP over the TCLP is that the
MEP gradually removes excess alkalinity in
the waste. Thus, the leaching behavior of
metal contaminants can be evaluated as a
function of decreasing pH, which increases
the solubility of most metals.
4. Shake Extraction of Solid
Waste with Water or Neutral
Leaching Procedure
The Shake Extraction of Solid Waste with
Water, or the Neutral Leaching Procedure,
was developed by the American Society for
Testing and Materials (ASTM) to assess the
leaching potential of solid waste and has been
designated as ASTM D-3987-85. This test
method provides for the shaking of an extrac-
tant (e.g., water) and a known weight of
waste of specified composition to obtain an
aqueous phase for analysis after separation.
The intent of this test method is for the final
pH of the extract to reflect the interaction of
the liquid extractant with the buffering capac-
ity of the solid waste.
The shake test is performed by mixing the
solid sample with test water and agitating
continuously for 18±0.25 hours. A liquid-to-
solid ratio of 20:1 by weight is used. After
agitation the solids are filtered from the liquid
extract, and the liquid is analyzed.
The water extraction is meant to simulate
conditions where the solid waste is the domi-
nant factor in determining the pH of the
extract. This test, however, has only been
approved for certain inorganic constituents,
and is not applicable to organic substances
and volatile organic compounds (VOCs). A
copy of this procedure can be ordered by
calling ASTM at 610 832-9585 or online at
.
III. Waste
Characterization
of Volatile
Organic
Emissions
To determine whether volatile organic
emissions are of concern at a waste manage-
ment unit, determine the concentration of the
VOCs that are reasonably expected to be
emitted. Process knowledge is likely to be
less accurate for determining VOCs than
measured values. As discussed earlier in this
chapter, modeling results for waste manage-
ment units will only be as accurate as the
input data. Therefore, sampling and analytical
testing might be necessary if organic concen-
trations cannot be estimated confidently
using process knowledge.
Table 2 in Chapter 5-Protecting Air Quality
can be used as a starting point to help you
determine which air emissions constituents to
measure. It is not recommended that you
sample for all of the volatile organics listed in
Table 2, but rather use Table 2 as a guide in
conjunction with process knowledge to nar-
row the sampling effort and thereby minimize
2-13
-------
Getting Started—Characterizing Waste
unnecessary sampling costs. A thorough
understanding of process knowledge can help
you determine what is reasonably expected to
be in die waste, so that it is not necessary to
sample for unspecified constituents.
Many tests have been developed for quan-
titatively extracting volatile and semi-volatile
organic constituents from various sample
matrices. These tests tend to be highly
dependent upon the physical characteristics
of die sample. You should consult with state
and local regulatory agencies before imple-
menting testing. You can refer to SW-846
Method 3500B for guidance on the selection
of methods for quantitative extraction or
dilution of samples for analysis by one of the
volatile or semi-volatile determinative meth-
ods. After performing the appropriate extrac-
tion procedure, further cleanup of the sample
extract might be necessary if analysis of the
extract is prevented due to interferences
coextracted from die sample. Method 3600
of SW-846 provides additional guidance on
cleanup procedures.
Following sample preparation, a sample is
ready for further analysis. Most analytical
mediods use either gas chromatography
(GC), high performance liquid chromatogra-
phy (HPLC), gas chromatography/mass spec-
trometry (GC/MS), or high performance
liquid chromatography/mass spectrometry
(HPLC/MS). SW-846 is designed to allow the
methods to be mixed and matched, so that
sample preparation, sample cleanup, and
analytical methods can be properly
sequenced for the particular analyte and
matrix. Again, you should consult with state
and local regulatory agencies before finalizing
die selected methodology.
2-14
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Getting Started—Characterizing Waste
Waste Characterization Activity List
To determine constituent concentrations in a waste you should:
D Assess the physical state of the waste using process knowledge.
D Use process knowledge to identify constituents for further analysis.
D Assess the environment in which the waste will be placed.
D Consult with state and local regulatory agencies to determine any specific testing requirements.
D Select an appropriate leachate test or organic constituent analysis based on the above information.
2-15
-------
Getting Started—Characterizing Waste
Resources
ASTM. 1995. Annual Book of ASTM Standards.
ASTM. Standard Methods for Examination of Water and Wastewater.
ASTM. D-3987-85. Standard Test Method for Shake Extraction of Solid Waste with Water
California EPA. Handbook for the Analysis and Classification of Wastes.
California EPA. 1995. Preliminary Proposal to Require the TCLP in Lieu of the Waste Extraction
Test. Memorandum to James Carlisle, Department of Toxics Substances Control, from Jon
Marshack, California Regional Water Quality Control Board. December 18.
California EPA. 1994. Regulation Guidance: When Extraction Tests are Not Necessary.
California EPA. 1994. Regulation Guidance: TCLP vs. WET.
California EPA. 1993. Regulation Guidance: Lab Methods.
California EPA. 1993. Regulation Guidance: Self-Classification.
Cochran, WG. 1977. Sampling Techniques. Third Edition. New York: John Wiley and Sons.
Dusing, D.C., Bishop, P.L., and Keener, T.C. 1992. Effect of Redox Potential on Leaching from
Stabilized/Solidified Waste Materials. Journal of Air and Waste Management Association. 42:56.
January.
Gilbert, R.O. 1987. Statistical Methods for Environmental Pollution Monitoring. New York: Van
Nostrand Reinhold Company.
Kendall, Douglas. 1996. Impermanence of Iron Treatment of Lead-Contaminated Foundry Sand—
NIBCO, Inc., Nacogdoches, Texas. National Enforcement Investigations Center Project PA9. April.
Kosson, D.S., H.A. van der Sloot, E Sanchez, and A.C. Garrabrants. 2002. An Integrated
Framework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials.
Environmental Engineering Science, In-press.
New Jersey Department of Environmental Protection. 1996. Industrial Pollution Prevention Trends
in New Jersey.
2-16
-------
Getting Started—Characterizing Waste
Resources (cont.)
Northwestern University. 1995. Chapter 4—Evaluation of Procedures for Analysis and Disposal of
Lead- Based Paint-Removal Debris. Issues Impacting Bridge Painting: An Overview. Infrastructure
Technology Institute. FHWA/RD/94/098. August.
U.S. EPA 2002. Industrial Waste Managment Evaluation (IWEM) Technical Background Document.
EPA530-R-02-012.
U.S. EPA. 1998a. Guidance on Quality Assurance Project Plans: EPA QA/G-5. EPA600-R-98-018.
U.S. EPA. 1998b. Guidance on Sampling Designs to Support QA Project Plans. QA/G-5S
U.S. EPA. 1997. Extraction Tests. Draft.
U.S. EPA. 1996a. Guidance for the Data Quality Assessment: Practical Methods for Data Analysis:
EPAQA/G-91. EPA600-R-96-084.
U.S. EPA. 1996b. Guidance for the Data Quality Objectives Process: EPA QA/G-4. EPA600-R-96-055.
U.S. EPA. 1996c. Hazardous Waste Characteristics Scoping Study.
U.S. EPA. 1996d. National Exposure Research Laboratory (NERL)-Las Vegas: Site Characterization
Library, Volume 2.
U.S. EPA. 1996e. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. Third
Edition.
U.S. EPA. 1995. State Requirements for Non-Hazardous Industrial Waste Management Facilities.
U.S. EPA. 1993. Identifying Higher-Risk Wastestreams in the Industrial D Universe: The State
Experience. Draft.
U.S: EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-088.
U.S..EPA Science Advisory Board. 1991. Leachability Phenomena: Recommendations and Rationale for
Analysis of Contaminant Release by the Environmental Engineering Committee. EPA-SAB-EEC-92-003.
Winer; .BJ. 1971. Statistical Principles in Experimental Design. New York: McGraw-Hill.
2-17
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Getting Started—Characterizing Waste
Appendix: Example Extraction Tests (Draft 9/30/97)
Test Method Leaching Fluid
Liquid:Solid Maximum Number of Time of Comments
Ratio Particle Size Extractions Extractions
I. Static Tests
A. Agitated Extraction Tests
Toxicity
Characteristic
Leaching
Procedure (1311)
Extraction
Procedure
Toxicity Test (1310)
ASTM D3987-85
Shake Extraction
of Solid Waste
with Water
California WET
Ultrasonic
Agitation
Method for
Accelerating Batch
Leaching Test"
Alternative TCLP
for Construction,
Demolition and
Lead Paint
Abatement Debris'8
Extraction
Procedure for Oily
Waste (1330)
Synthetic
Precipitation
Leaching Procedure
(1312)
Equilibrium Leach
Test
0.1 N acetic acid solution,
pH 2.9, for alkaline wastes
0.1 N sodium acetate
buffer solution, pH 5.0,
for non-alkaline wastes
0.5 N acetic acid (pH-5.0)
ASTM IV reagent water
0.2 M sodium citrate
(pH- 5.0)
Distilled water
TCLP acetic acid solutions
Soxhlet with THF and
toluene EP on remaining
solids
#1 Reagent water to pH 4.2
with nitric and sulfuric
acids (60/40)
#2 Regent water to pH 5.0
with nitric and sulfuric
acids (60/40)
Distilled water
20:1
16:1 during
extraction
20:1 final
dilution
20:1
10:1
4:1
20:1
100g:300mL
20:1
20:1
4:1
9.5mm
9.5 mm
As in
environment
(as received)
2.0 mm
Ground
<9.5
9.5mm
9.5mm
150mm
1
1
1
1
1
1
3
1
1
18 ±2 hours
24 hours
18 hours
48 hours
30 minutes
8 hours
24 hours (EP)
18±2 hours
7 days
Co-disposal scenario might
not be appropriate; no
allowance for structural
integrity testing of
monolithic samples
High alkalinity samples can
result in variable data
Not validated for organics
Similar to EP, but sodium
citrate makes test more
aggressive
New — little performance
data
Uses heat to decrease
extraction time
ZHE option for organics
Determines contaminants
that have been insolubilized
by solidification
2-18
' Bisson, D.L.; Jackson D.R.; Williams K.R.; and Grube WE. J. Air Waste Manage. Assoc., 41: 1348-1354,
10 Olcrest, R. A Representative Sampling and Alternative Analytical Toxic Characteristic Leacha'te Procedure
Method for Construction, Demolition, and Lead Paint Abatement Debris Suspected of Containing Leachable
Lead, Appl. Occup. Environ. Hyg. 11(1), January 1996.
-------
Getting Started—Characterizing Waste
Test Method Leaching Fluid
Liquid:Solid Maximum Number of Time of
Ratio Particle Size Extractions Extractions
Comments
Static Leach Test
Method (material
characteristic
centre- 1)
High Temperature
Static Leach Tests
Method (material
characterization
centre-2)
Sequential
Extraction Tests
B. Non-Agitated Extraction Tests
Can be site specific, 3
standard leachates: water,
brine, silicate/bicarbonate
Same as MCC-1 (conducted
at 100°C)
VOL/surface
10cm
VOL/Surface
10cm
40mm2
surface area
40 mm3
Surface Area
1
1
>7 days
>7 Days
Series of optional steps
increasing complexity of
analysis
Series of optional steps
increasing complexity of
analysis
C. Sequential Chemical Extraction Tests
0.04 m acetic acid
50:1
9.5 mm
15
24 hours per
extraction
D. Concentration Build-Up Test
Sequential
Chemical
Extraction
Standard Leach
Test, Procedure C
(Wisconsin)
5 leaching solutions of
increasing acidity
DI water *SYN Landfill
Varies from
16.1 to 40.1
10:1,5:1,
7.5:1
150mm
As in
environment
5
3
Varies 3 or
14 days
3 or 14 days
Examines partitioning of
metals into different
fractions or chemicals forms
Sample discarded after each
leach, new sample added to
existing leachate
II. Dynamic Tests (Leaching Fluid Renewed)
A. Serial Batch (Particle)
Multiple Extraction
Procedure (1320)
Monofill Waste
Extraction
Procedures
Graded Serial Batch
(U.S. Army)
Sequential Batch
Ext. of Waste with
Water ASTM
D-4793-93
Same as EP TOX, then
with synthetic acid rain
(sulfuric acid, nitric acid
in 60:40% mixture)
Distilled/deionized water
or other for specific site
Distilled water
Type IV reagent water
20:1
10:1 per
extraction
Increases
from 2:1 to
96:1
20:1
9.5 mm
9.5 mm or
monolith
N/A
As in
environment
9 (or more)
4
>7
10
24 hours per
extraction
18 hours per
extraction
Until steady
stale
18 hours
2-19
-------
Getting Started—Characterizing Waste
Test Method Leaching Fluid
Liquid:Solid Maximum Number of Time of Comments
Ratio Particle Size Extractions Extractions
Use of Chelaling
Agent to Determine
the Metal
Availability for
Leaching Soils and
Wastes"
Demineralized water with
EDTA, sample to a final
pH of 7±0.5
50 or 100
<300 um
1
18, 24, or
48 hours
Experimental test based on
Method 7341
B. Flow Around Tests
IAEA Dynamic
Leach Test
(International
Atomic Energy
Agency)
Leaching Tests on
Solidified Products12
DLT
DI water/site water
0.1N acetic acid
DI water
N/A
20:1
(Procedure A)
2:1 (6 hrs.)
&10:1
(18 hrs.)
(Procedure B)
N/A
One face
prepared
0.6 um-70um
Surface
washing
>19
1
18
>6 months
24 hours
196 days
S/S technologies most valid
when applied to wastes
contaminated by inorganic
pollutants
C. Flow Through Tests
ASTM D4874-95
Column Test
Type IV reagent water
One void
volume
10 mm
1
24 hours
III. Other Tests
MCC-5s Soxhlet
Test (material
characteristic center)
ASTM C1308-95
Accelerated Leach
Test"
Generalized Acid
Neutralization
Capacity Test1*
Acid Neutralization
Capacity
Dl/site water
Acetic acid
HNO3, solutions of
increasing strength
100:1
20:1
3:1
Out and
washed
Able to pass
through an
ASTM No. 40
sieve
150mm
1
1
1
0.2 mVmin
48 hours
48 hours per
extraction
Only applicable if diffusion
is dominant leaching
mechanism
Quantifies the alkalinity of
binder and characterizes
buffering chemistry
2-20
" Garrabrants, A.C. and Koson, D.S.; Use of Chelating Agent to Determine the Metal Availability for Leaching
from Soils and Wastes, unpublished.
n Leaching Tests on Solidified Products; Gavasci, R., Lombardi, E, Polettine, A., and Sirini, P.
" C1308-95 Accelerated Leach Test for Diffusive Releases from Solidified Waste and a Computer Program to
Model Diffusive, Fractional Leaching from Cylindrical Wastes.
" Generalized Acid Neutralization capacity Test; Isenburg, J. and Moore, M.
-------
Part I
Getting Started
Chapter 3
Integrating Pollution Prevention
-------
Contents
I. Benefits of Pollution Prevention 3 - 3
II. Implementing Pollution Prevention 3 - 5
A. Source Reduction 3 - 5
B. Recycling .-. 3 - 7
C. Treatment 3 - 8
III. Where to Find Out More: Technical and Financial Assistance 3 - 10
Integrating Pollution Prevention Activity List 3 - 14
Resources '. - 3 - 15
Figure 1: Waste Management Hierarchy 3 - 2
-------
Getting Started—Integrating Pollution Prevention
Integrating Pollution Prevention
This chapter will help you:
• Consider pollution prevention options when designing a waste
management system. Pollution prevention will reduce waste dis-
posal needs and can minimize impacts across all environmental
media. Pollution prevention can also reduce the volume and toxi-
city of waste. Lastly, pollution prevention can ease some of the
burdens, risks, and liabilities of waste management.
Pollution prevention describes a vari-
ety of practices that go beyond tra-
ditional environmental compliance
or single media permits for water,
air, or land disposal and begin to
address the concept of sustainability in the
use and reuse of natural resources. Adopting
pollution prevention policies and integrating
pollution prevention into operations provide
opportunities to reduce the volume and toxic-
ity of wastes, reduce waste disposal needs,
and recycle and reuse materials formerly han-
dled as wastes. In addition to potential sav-
ings on waste management costs, pollution
prevention can help improve the interactions
This chapter will help address the fol-
lowing questions , - -'
• What are some of the benefits of pol-
lution prevention? ' '„
° Where can assistance in identifying
and implementing specific pollution
prevention options be obtained7
among industry, the public, and regulatory
agencies. It can also reduce liabilities and risks
associated with releases from waste manage-
ment units and closure and post-closure care
of waste management units.
Pollution prevention is comprehensive.
It emphasizes a life-cycle approach to assess-
ing a facility's physical plant, production
processes, and products to identify the best
opportunities to minimize environmental
impacts across all media. This approach also
ensures that actions taken in one area will not
increase environmental problems in another
area, such as reducing wastewater discharges
but increasing airborne emissions of Volatile
organic compounds. Pollution prevention
requires creative problem solving by a broad
cross section of employees to help achieve
environmental goals. In addition to the envi-
ronmental benefits, implementing pollution
prevention can often benefit a company in
many other ways. For example, redesigning
production processes or finding alternative
material inputs can also improve product
quality, increase efficiency, and conserve raw
materials. Some common examples of pollu-
tion prevention activities include: redesigning
3-1
-------
Getting Started—Integrating Pollution Prevention
processes or products'to reduce raw material'
needs and the volume of waste generated;
replacing solvent based cleaners with aqueous
based cleaners or mechanical cleaning sys-
tems; and instituting a reverse distribution
system where shipping packaging is returned
to the supplier for reuse rather than discard.
The Pollution Prevention Act of-1990
established a national policy to first, prevent
or reduce waste at the point of generation
(source reduction); second, recycle or reuse
waste materials; third, treat waste; and finally,
dispose of remaining waste in an environ-
mentally protective manner (see Figure 1).
Some states and many local governments
have adopted similar policies, often with
more specific and measurable goals.
Source Reduction means any practice
which (i) reduces the amount of any sub-
stance, pollutant, or contaminant entering
any wastestream or otherwise released into
the environment, prior to recycling, treat-
ment, or disposal; and (ii) reduces the risks
to public health and the environment associ-
ated'with the release of such substances, pol-
lutants, or contaminants.
Recycling requires an examination of
waste streams and production processes to
identify opportunities. Recycling and benefi-
cially reusing wastes can help reduce disposal
costs, while using or reusing recycled materi-
als as substitutes for feedstocks can reduce
raw materials costs. Materials exchange pro-
grams can assist in finding uses for recycled
materials and in identifying effective substi-
tutes for raw materials. Recycling not only
helps reduce the overall amount of waste sent
for disposal, but also helps conserve natural
resources by replacing the need for virgin
materials.
Treatment can reduce the volume and
toxicity of a waste. Reducing a wastes volume
and toxicity prior to final disposal can result
in long-term cost savings. There are a consid-
erable number of levels and types of treat-
ment from which to choose. Selecting the
right treatment option can help simplify dis-
posal options and limit future liability.
Figure 1. Waste Management Hierarchy
n
Waste Management Hierarchy
If NO
Disposal
3-2
-------
Getting Started—Integrating Pollution Prevention
Over the past 10 years, interest in all aspects
of pollution prevention has blossomed, and
governments, businesses, academic and
research institutions, and individual citizens
have dedicated greater resources to it. Many
industries are adapting pollution prevention
practices to fit their individual operations.
Pollution prevention can be successful when
flexible problem-solving approaches and solu-
tions are implemented. Fitting these steps into
your operations business and environmental
goals will help ensure your programs success.
Throughout the Guide several key steps are
highlighted that are ideal points for imple-
menting pollution prevention to help reduce
waste management costs, increase options, or
reduce potential liabilities by reducing risks
that the wastes might pose. For example:
Waste characterization is a key compo-
nent of the Guide. It is also a key component
of a pollution prevention opportunity assess-
ment. An opportunity assessment, however, is
more comprehensive since it also covers mate-
rial inputs, production processes, operating
practices, and potentially other areas such as
inventory control. When characterizing a
waste, consider expanding the opportunity
assessment to cover these aspects of the busi-
ness. An opportunity assessment can help
identify the most efficient, cost-effective, and
environmentally friendly combination of
options, especially when planning new prod-
ucts, new or changed waste management prac-
tices, or facility expansions.
Land application of waste might be a pre-
ferred waste management option because land
application units can manage wastes with high
liquid content, treat wastes through biodegra-
dation, and improve soils due to the organic
material in the waste. Concentrations of con-
stituents might limit the ability to take full
advantage of land application. Reducing the
concentrations of constituents in the waste
before it is generated or treating the waste prior
to land application can provide the flexibility to
use land application and ensure that the prac-
tice will be protective of human health and the
environment and limit future liabilities.
L Benefits of
Pollution
Prevention
Pollution prevention activities benefit
industry, states, and the public by protecting
the environment and reducing health risks,
and also provide businesses with financial and
strategic benefits.
Protecting human health and the envi-
ronment. By reducing the amount of contami-
nants released into the environment and the
volume of waste requiring disposal, pollution
prevention activities protect human health and
the environment. Decreasing the volume or
toxicity of process materials and wastes can
reduce worker exposure to potentially harmful
constituents. Preventing the release and dis-
posal of waste constituents to the environment
also reduces human and wildlife exposure and
habitat degradation. Reduced consumption of
raw materials and energy conserves precious
natural resources. Finally reducing the volume
of waste generated decreases the need for con-
struction of new waste management facilities,
preserving land for other uses such as recre-
ation or wildlife habitat.
Cost savings. Many pollution prevention
activities make industrial processes and equip-
ment more resource-efficient. This increased
production efficiency saves raw material and
labor costs, lowers maintenance costs due to
newer equipment, and potentially lowers over-
sight costs due to process simplification. When
planning pollution prevention activities, con-
sider the cost of the initial investment for
audits, equipment, and labor. This cost will
3-3
-------
Getting Started—Integrating Pollution Prevention
vary depending on
the size and com-
plexity of waste
reduction activi-
ties. In addition,
consider the pay-
back time for the
investment.
Prioritize pollution
prevention activi-
ties to maximize
cost savings and
health and envi-
ronmental benefits.
Simpler design and operating conditions.
Reducing the risks associated with wastes can
allow wastes to be managed under less strin-
gent design and operating conditions. For
example, the ground-water tool in Chapter 7,
Section A - Assessing Risk might indicate that
a composite liner is recommended for a specif-
ic waste stream. A pollution prevention oppor-
tunity assessment also might imply that by
implementing a pollution prevention activity
that lowers the concentrations of one or two
problematic waste constituents in that waste
stream, a compacted clay liner can provide
sufficient protection. When the risks associat-
ed with waste disposal are reduced, the long-
term costs of closure and post-closure care can
also be reduced.
Improved work-
er safety. Processes
involving less toxic
and less physically
dangerous materials
can improve worker
safety by reducing
work-related injuries
and illnesses. In
addition to strength-
ening morale,
improved worker
safety also reduces
health-related costs from lost work .days,
health insurance, and disability payments.
Lower liability. A well-operated unit mini-
mizes releases, accidents, and unsafe waste-
handling practices. Reducing the volume and
toxicity of waste decreases the impact of these
events if they occur. Reducing potential liabili-
ties decreases the likelihood of litigation and
cleanup costs.
Higher product quality. Many corporations
have found that higher product quality results
from some pollution prevention efforts. A sig-
nificant part of the waste in some operations
consists of products that fail quality inspec-
tions, so minimizing waste in those cases is
inextricably linked with process changes that
improve quality. Often, managers do not realize
how easy or technically feasible such changes
are until the drive for waste reduction leads to
exploration of the possibilities. :
Building community relations. Honesty
and openness can strengthen credibility
between industries, communities, and regula-
tory agencies. If you are implementing a pollu-
tion prevention' program, make people aware
of it. Environmental protection and economic
growth can be compatible objectives.
Additionally, dialogue among all parties in the
development of pollution prevention plans can
help identify and address concerns.
3-4
-------
Getting Started—Integrating Pollution Prevention
II. Implementing
Pollution
Prevention
When implementing pollution prevention,
consider a combination of options that best
fits your facility and its products. There are a
number of steps common to implementing
any facility-wide pollution prevention effort.
An essential starting point is to make a clear
commitment to identifying and taking advan-
tage of pollution prevention opportunities.
Seek the participation of interested partners,
develop a policy statement committing the
industrial operation to pollution prevention,
and organize a team to take responsibility for
it. As a next step, conduct a thorough pollu-
tion prevention opportunity assessment.,Such
an assessment will help set priorities accord-
ing to which options are the most promising.
Another feature common to many pollution
prevention programs is measuring the pro-
gram's progress.
The actual pollution prevention practices
implemented are the core of a program. The
following sections give a brief overview of
these core activities: source reduction, recy-
cling, and treatment. To find out more, con-
tact some of the organizations listed
throughout this chapter.
A. Source Reduction
As defined in the Pollution Prevention Act
of 1990, source reduction means any practice
which (i) reduces the amount of any haz-
ardous substance, pollutant, or contaminant
entering any wastestream or otherwise
* released into the environment, prior to recy-
cling, treatment, or disposal; and (ii) reduces
the hazards to public health and the environ-
ment associated with the release of such sub-
stances, pollutants, or contaminants. The
term includes equipment or technology mod-
ifications; process or procedure modifica-
tions; reformulations or redesign of products;
substitution of raw materials; and improve-
' ments in housekeeping, maintenance, train-
ing, or inventory control.
Reformulation
or redesign of
products. One
source reduction
option is to refor-
mulate or redesign
products and
processes to incor-
porate materials
more likely to pro-
duce lower-risk
wastes. Some of the
most common
practices include eliminating metals from
inks, dyes, and paints; reformulating paints,
inks, and adhesives to eliminate synthetic
organic solvents; and replacing chemical-
based cleaning solvents with water-based or
citrus-based products. Using raw materials
free from even trace quantities of contami-
nants, whenever possible, can also help
reduce waste at the source.
When substituting materials in an industri-
al process, it is important to examine the
effect on the entire waste stream to ensure
that the overall risk is being reduced. Some
changes can shift contaminants to another
medium rather than actually reduce waste
generation. Switching from solvent-based to
water-based cleaners, for example, will
reduce solvent volume and disposal cost, but
is likely to dramatically increase wastewater
volume. Look at the impact of wastewater
generation on effluent limits and wastewater
treatment sludge production.
Technological modifications. Newer
process technologies often include better
waste reduction features than older ones. For
industrial processes that predate considera-
3-5
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Getting Started—Integrating Pollution Prevention
tion of waste and risk reduction, adopting
new procedures or upgrading equipment can
reduce waste volume, toxicity, and manage-
ment costs. Some examples include redesign-
ing equipment to cut losses during batch
changes or during cleaning and maintenance,
changing to mechanical cleaning devices to
avoid solvent use, and installing more energy-
and material-efficient equipment. State tech-
nical assistance centers, trade associations,
and other organizations listed in this chapter
can help evaluate the potential advantages
and savings of such improvements.
In-process recycling (reuse). In-process
recycling involves the reuse of materials, such
as cutting scraps, as inputs to the same
process from which they came, or uses them
in other processes or for other uses in the
facility. This furthers waste reduction goals by
reducing the need for treatment or disposal
and by conserving energy and resources. A
common example of in-process recycling is
the reuse of wastewater.
Good housekeeping procedures. Some of
the easiest, most cost-effective, and most wide-
ly used waste reduction techniques are simple
improvements in housekeeping. Accidents and
spills generate avoidable disposal hazards and
expenses. They are less likely to occur in
clean, neatly organized facilities.
Good housekeeping techniques that reduce
the likelihood of accidents and spills include
training employees to manage waste and
materials properly; keeping aisles wide and
free of obstructions; clearly labeling contain-
ers with content, handling, storage, expira-
tion, and health and safety information;
spacing stored materials to allow easy access;
surrounding storage areas with containment
berms to control leaks or spills; and segregat-
ing stored materials to avoid cross-contami-
nation, mixing of incompatible materials, and
unwanted reactions. Proper employee train-
ing is crucial to implementing a successful
waste reduction program, especially one fea-
turing good housekeeping procedures. Case
study data indicate that effective employee
training programs can reduce waste disposal
volumes by 10 to 40 percent.1
Regularly scheduled maintenance and
plant inspections are also useful. Maintenance
helps avoid the large cleanups and disposal
operations that can result from equipment
failure. Routine maintenance also ensures that
equipment is operating at peak efficiency, sav-
ing energy, time, and materials. Regularly
scheduled or random, unscheduled plant
inspections help identify potential problems
before they cause waste management prob-
lems. They also help identify areas where
improving the efficiency of materials manage-
ment and handling practices is possible. If
possible, plant inspections, periodically per-
formed by outside inspectors who are less
familiar with day-to-day plant operations, can
bring attention to areas for improvement that
are overlooked by employees accustomed to
the plants routine practices.
Storing large volumes of raw materials
increases the risk of an accidental spill and
the likelihood that the materials will not be
used due to changes in production schedules,
new product formulations, or material degra-
dation. Companies are sometimes forced to
dispose of materials whose expiration dates
have passed or that are no longer needed.
Efficient inventory control allows a facility to
avoid stocking materials in excess of its abili-
ty to use them, thereby decreasing disposal
volume and cost. Many companies have suc-
cessfully implemented "just-in-time" manu-
facturing systems to avoid the costs and risks
associated with maintaining a large onsite
inventory In a "just-in-time" manufacturing
system, raw materials arrive as they are need-
ed and only minimal inventories are main-,
tained on site.
1 Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc. p. 13.
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Getting Started—Integrating Pollution Prevention
Segregating waste streams is another good
housekeeping procedure that enables a facili-
ty to avoid contaminating lower risk wastes
with hazardous constituents from another
source. Based on a waste characterization
study, it might be more efficient and cost-
effective to manage wastes separately by recy-
cling some, and treating or disposing of
others. Waste segregation can also help
reduce the risks associated with handling
waste. Separating waste streams allows some
materials to be reused, resulting in additional
cost savings. Emerging markets for recovered
industrial waste materials are creating new
economic incentives to segregate waste
streams. Recovered materials are more attrac-
tive to potential buyers if it can be ensured
that they are not tainted with other waste
materials. For example, if wastes from metal-
finishing facilities are segregated by type,
metal-specific-bearing sludge can be recov-
ered more economically and the segregated
solvents and waste oils can be recycled.
B. Recycling
Recycling involves col- ,,
lecting, processing, and i
reusing materials that
would otherwise be han-
dled as wastes. The fol-
lowing discussion highlights a few of the
ways to begin this process.
Materials exchange programs. Many local
governments and states have established mate-
rials exchange programs to facilitate transac-
tions between waste generators and industries
that can use wastes as raw materials. Materials
exchanges are an effective and inexpensive way
to find new users and uses for a waste. Most
are publicly funded, nonprofit organizations,
although some charge a nominal fee to be list-
ed with them or to access their online databas-
es. Some actively work to promote exchanges
between generators and users, while others
simply publish lists of generators, materials,
and buyers. Some waste exchanges also spon-
sor workshops and conferences to discuss
waste-related regulations and to exchange
information. More than 60 waste and materials
exchanges operate in North America. Below
are four examples of national, state, and local
exchange programs. Each program's Web site
also provides links to other regional, national,
and international materials exchange net-
works.
• ERAS; Jobs Through Recycling
Web site provides descriptions
of and links to international, national,
and state-specific materials exchange
programs and organizations.
• Recycler's World is a world-wide
materials trading site with links to
dozens of state and regional exchange
networks.
• CalMAX (California Materials
Exchange) is maintained by the
California Integrated Waste
Management Board and facilitates
waste exchanges in California and
provides links to other local and
national exchange programs.
• King County, Washington's IMEX
is a local industri-
al materials exchange program that
also provides an extensive list of
state, regional, national, and interna-
tional exchange programs.
Beneficial use. Beneficial use involves
substituting a waste material for another
material with similar properties. Utility com-
panies, for example, often use coal combus-
tion ash as a construction material, road base,
or soil stabilizer. The ash replaces other, non-
3-7
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Getting Started—Integrating Pollution Prevention
recycled materials, such as fill or Portland
cement, not only avoiding disposal costs but
also generating revenue. Other examples of
beneficial use include using wastewaters and
sludges as soil amendments (see Chapter 7,
Section C-Designing a Land Application
Program) and using foundry sand in asphalt,
concrete, and roadbed construction.
Many regulatory agencies require approval
of planned beneficial use activities and may
require testing of the materials to be reused.
Others may allow certain wastes to be desig-
nated for beneficial use, as long as die required
analyses are completed. Pennsylvania, for
example, allows application of a "coproduct"
designation to, and exemption from waste reg-
ulations for "materials which are essentially
equivalent to and used in place of an inten-
tionally manufactured product or produced
raw material and... [which present] no greater
risk to the public or the environment."
Generally, regulatory agencies want to ensure
that any beneficially used materials are free
from significantly increased levels of con-
stituents that might pose a greater risk than
the materials they are replacing. Consult with
the state agency for criteria and regulations
governing beneficial use.
In a continuing effort to promote the use of
materials recovered from solid waste, the
Environmental Protection Agency (EPA) has
instituted the Comprehensive Procurement
Guideline (CPG) program. Using recycled-con-
tent products ensures that materials collected
in recycling programs will be used again in the
manufacture of new products. The CPG pro-
gram is authorized by Congress under Section
6002 of the Resource Conservation and
Recovery Act (RCRA) and Executive Order
13101. Under the CPG program, EPA is
required to designate products that are or can
be made with recovered materials and to rec-
ommend practices for buying these products.
Once a product is designated, procuring agen-
cies are required to purchase it with the high-
est recovered material content level practica-
ble. As of January 2001, EPA has designated
54 items within eight product categories
including items such as retread tires, cement
and concrete containing coal fly ash and
ground granulated blast furnace slag, traffic
barricades, playground surfaces, landscaping
products, and nonpaper office products like
binders and toner cartridges. While directed
primarily at federal, state, and local procuring
agencies, CPG information is helpful to every-
one interested in purchasing recycled-content
products. For further information on the CPG
program, visit: .
C. Treatment
Treatment of non-hazardous industrial
waste is not a federal requirement, however,
it can help to reduce the volume and toxicity
of waste prior to disposal. Treatment can also
make a waste amenable for reuse or recycling.
Consequently, a facility managing non-haz-
ardous industrial waste might elect to apply
treatment. For example, treatment might be
incorporated to address volatile organic com-
pound (VOC) emissions from a waste manag-
ment unit, of a facility might elect to treat a
waste so that a less stringent waste manage-
ment system design could be used. Treatment
involves changing a wastes physical, chemi-
cal, or biological character or composition
through designed techniques or processes. ,
There are three primary categories of treat-
ment—physical, chemical, and biological.
Physical treatment involves changing the
waste's physical properties such as its size,
shape, density, or state (i.e., gas, liquid, solid).
Physical treatment does not change a wastes
chemical composition. One form of physical •
treatment, immobilization, involves encapsu-
lating waste in other materials, such as plastic,
resin, or cement, to prevent constituents from
volatilizing or leaching. Listed below are a few
examples of physical treatment.
3-8
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Getting Started—Integrating Pollution Prevention
• Immobilization:
Encapsulation
Thermoplastic binding
• Carbon absorption:
Granular activated carbon (GAC)
Powdered activated carbon (PAC)
• Distillation:
Batch distillation
Fractionation
Thin film extraction
Steam stripping ,
Thermal drying
• Filtration
• Evaporation/volatilization
• Grinding
• • Shredding
•. Compacting
• Solidification/addition of absorbent
material
Chemical treatment involves altering a
waste's chemical composition, structure, and
properties through chemical reactions.
Chemical treatment-can consist of mixing the
waste with other materials (reagents), heating
the waste to high temperatures, or a combi-
nation of both. Through chemical treatment,
waste constituents can be recovered or
destroyed. Listed below are a few examples of
chemical treatment.
• Neutralization
• Oxidation
• Reduction
• Precipitation
• Acid leaching
• Ion exchange
• Incineration
• Thermal desorption
• Stabilization
• Vitrification
• Extraction:
Solvent extraction
Critical extraction
• High temperature metal recovery
(HTMR)
Biological treatment can be divided into two
categories-aerobic and anaerobic. Aerobic bio-
logical treatment uses oxygen-requiring
microorganisms to decompose organic and
non-metallic constituents into carbon dioxide,
water, nitrates, sulfates, simpler organic prod-
ucts, and cellular biomass (i.e., cellular growth
and reproduction). Anaerobic biological treat-
ment uses microorganisms, in the absence of
oxygen, to transform organic constituents and
nitrogen-containing compounds into oxygen
and methane gas (CH4(g)). Anaerobic biologi-
cal treatment typically is performed in an
enclosed digester unit. Listed below are a few
examples of biological treatment.
• Aerobic:
Activated sludge
Aerated lagoon
Trickling filter
Rotating biological contactor (RBC)
• ' Anaerobic digestion
The range of treatment methods from
which to choose is as diverse as the range of
wastes to be treated. More advanced treat-
ment will generally be more expensive, but
by reducing the quantity and risk level of the
waste, costs might be reduced in the long
run. Savings could come from not only lower
disposal costs, but also lower closure and
post-closure care costs. Treatment and post-
treatment waste management methods can be
selected to minimize both total cost and envi-
ronmental impact, keeping in mind that treat-
ment residuals, such as sludges, are wastes
themselves that will need to be managed.
3-9
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Getting Started—Integrating Pollution Prevention
Where to Find
Out More:
Technical and
Financial
Assistance
There is a wealth of information available to
help integrate pollution prevention into an
operation. As a starting point, a list of refer-
ences to technical and financial resources is
included in this section. The Internet can be
an excellent source of background information
on the various resources to help begin the
search for assistance. Waste reduction informa-
tion and technologies are constantly changing.
To follow new developments you should main-
tain technical and financial contacts and con-
tinue to use these resources even after
beginning waste reduction activities. Eventual-
ly, you can build a network of contacts to sup-
port all your various technical-needs.
Where Can Assistance Be
Obtained?
Several types of organizations offer assis-
tance. These include offices in regulatory
agencies, university departments, nonprofit
foundations, and trade associations.
Additionally, the National Institute of
Standards and Technology (NIST) Manu-
facturing Extension Partnerships (MEPs)
also provide waste
reduction information. Look for waste reduc-
tion staff within the media programs (air,
water, solid/hazardous waste) of regulatory
agencies or in the state commissioner's office,
special projects division, or pollution preven-
tion division. Some states also provide techni-
cal assistance for waste reduction activities,
such as recycling, through a business advo-
cate or small business technical assistance
program. EPA's U.S. State & Local Gateway
Web site is a helpful tool for
locating your state environmental agency.
The listings below identify some primary
sources for technical assistance that might
prove helpful. This list serves as a starting
point only and is by no means exhaustive.
There are many additional organizations that
offer pollution prevention assistance on
regional, state, and local levels.'
• American Forest and Paper
Association (AF&PA) is the nation-
- al trade association of the forest,
paper, and wood products industries.
It offers documents that might help
you find buyers for wood and paper
wastes, Phone:
800 878-8878 e-mail: INFO®
afandpa.ccmail.compuserve.com
• California Integrated Waste
Management Board. This Web site
contains general waste prevention
background and business waste
reduction program overviews, fact
sheets, and information about market
development for recycled materials
and waste reduction training.
• Center for Environmental Research
Information (CERI) provides techni-
cal guides and manuals on waste
reduction, summaries of pollution
prevention opportunity assessments,
3-10
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Getting Started—Integrating Pollution Prevention
and waste reduction alternatives for
specific industry sectors.
Phone: 513^-569-7562 e-mail:
ord.ceri@epamail.epa.gov
Enviro$en$e, part of the U.S. EPA's
Web site, provides a single repository
for pollution prevention, compliance
assurance, and enforcement informa-
tion and data bases. Its search engine
searches multiple Web sites (inside
and outside the EPA), and offers
assistance in preparing a search.
National Pollution Prevention
Roundtable (NPPR) promotes the
development, implementation, and
'evaluation of pollution prevention.
NPPR's Web site provides an abridged
online version of The Pollution
Prevention Yellow Pages ,
a listing of local, state, regional and
national organizations, including
state and local government programs,
federal agencies, EPA pollution pre-
vention coordinators, and non-profit
groups that work on pollution pre-
vention. Phone: 202
466-P2P2
P2 GEMS. This site, an Internet
search tool operated by the
Massachusetts Toxics Use Reduction
Institute, can help facility planners,
engineers, and managers locate
process and materials management
information over the Web. It includes
information on over 550 sites valu-
able for toxics use reduction planning
and pollution prevention.
Pollution Prevention Information
Clearinghouse (PPIC). PPIC main-
tains a collection of EPA non-regula-
tory documents related to waste
reduction, Phone: 202
260-1023 e-mail: ppic@epamail.
epa.gov
• U.S. Department of Energy (DOE)
Industrial Assessment Centers
(lACs). DOE's Office of Industrial
Technologies sponsors free industrial
assessments for small and medium-
sized manufacturers. Teams of engi-
neering students from the centers
conduct energy audits or industrial
assessments and provide recommen-
dations to manufacturers to help
them identify opportunities to
improve productivity, reduce waste,
and save energy,
-------
Getting Started—Integrating Pollution Prevention
technologies by providing technical
information, financing, training, and
other services. The NIST Web site
has a locator that
can help you find the nearest center.
Trade associations. Trade associa-
tions provide industry-specific assis-
tance through publications,
workshops, field research, and con-
sulting services. EPA's Waste Wise
program provides an online
resources directory which can help
you locate specific trade associations.
The National Trade and Professional
Associations of the Unites States'
Directory of Trade Associations
(Washington, DC: Columbia Books,
Inc., 2000) is another useful resource.
Onsite technical assistance audits.
These audits are for small (and some-
times larger) businesses. The assess-
ments, which take place outside of
the regulatory environment and on a
strictly voluntary basis, provide busi-
nesses with information on how to
save money, increase efficiency, and
improve community relations. DOE's
Office of Industrial Technologies
is one
example.
Facility planning assistance. A num-
ber of organizations can help busi-
nesses develop, review, or evaluate
facility waste reduction plans. State
waste reduction programs frequently
prepare model plans designed to
demonstrate activities a business can
implement to minimize waste.
Research and collaborative pro-
jects. Academic institutions, state
agencies and other organizations fre-
quently participate in research and
collaborative projects with industry
to foster development of waste
reduction technologies and manage-
ment strategies. Laboratory and field
research activities include studies,
surveys, database development, data
collection, and analysis.
Hotlines. Some states operate tele-
phone assistance services to provide
technical waste reduction information
to industry and the general public.
Hotline staff typically answer ques-
tions, provide referrals, and distribute
printed technical materials on request.
Computer searches and the
Internet. The Internet brings many
pollution prevention resources to a
user's fingertips. The wide range of
resources available electronically can
provide information about innovative
waste-reducing technologies, efficient
industrial processes, current state
and federal regulations, and many
other pertinent topics. Independent
searches can be done on the Internet,
and some states perform computer
searches to provide industry with
information about waste reduction.
EPA and many state agencies have
Web sites dedicated to these topics,
with case studies, technical explana-
tions, legal information, and links to
other sites for more information.
3-12
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Getting Started—Integrating Pollution Prevention
Workshops, seminars, and training.
State agencies, trade associations, and
other organizations conduct work-
shops, seminars, and technical train-
ing on waste reduction. These events
provide information, identity
resources, and facilitate networking.
Grants and loans. A number of
states distribute funds to independent
groups that conduct waste reduction
activities. These groups often use
such support to fund research and to
run demonstration and pilot projects.
3-13
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Getting Started—Integrating Pollution Prevention
Integrating Pollution
Prevention Activity List
To address pollution prevention you should:
D Make waste management decisions by considering the priorities set by the full range of pollution
prevention options—first, source reduction; second, reuse and recycling; third, treatment; last, dis-
posal.
D Explore the cost savings and other benefits available through activities that integrate pollution pre-
vention.
D Develop a waste reduction policy.
D Conduct a pollution prevention opportunity assessment of facility processes.
D Research potential pollution prevention activities. •
D Consult with public and private agencies and organizations providing technical and financial assis-
tance for pollution prevention activities.
D Plan and implement activities that integrate pollution prevention.
3-14
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Getting Started—Integrating Pollution Prevention
Resources
Erickson, S. and King, B. 1999. Fundamentals of Environmental Management. John Wiley and Sons,
Inc.
Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc.
"Green Consumerism: Commitment Remains Strong Despite Economic Pessimism." 1992. Cambridge
Reports. Research International. (October).
Habicht, E Henry. 1992. U.S. EPA Memorandum on EPA Definition of Pollution Prevention (May).
Higgins,, Thomas E., ed. 1995. Pollution Prevention Handbook. CRC-Lewis Publishers.
"Moving from Industrial Waste to Coproducts." 1997. Biocycle. (January)
National Pollution Prevention Roundtable. 1995. The Pollution Prevention Yellow Pages.
Pollution Prevention Act of 1990. (42 U.S.C. 13101 et seq., Pub.L. 101-508, November 5, 1990).
Rossiter, Alan P., ed. 1995. Waste Minimization Through Process Design. McGraw-Hill, Inc.
U.S. EPA.. 2001. Pollution Prevention Clearinghouse: Quarterly List of Pollution Prevention
Publications, Winter 2001. EPA742-F-01-004.
U.S. EPA.. 1998. Project XL: Good for the Environment, Good for Business, Good for Communities.
EPA100-F-98-008.
U.S. EPA. 1997. Developing and Using Production Adjusted Measurements of Pollution Prevention.
EPA600-R-97-048. . .. . .
U.S. EPA. 1997. Guide to Accessing Pollution Prevention Information Electronically. EPA742-B-97-003
U.S. EPA. 1997. Pollution Prevention 1997: A National Progress Report. EPA742-R-97-001.
U.S. EPA. 1997. Technical Support Document for Best Management Practices Programs—Spent
Pulping Liquor Management, Spill Prevention, and Control.
U.S. EPA. 1996. Environmental Accounting Project: Quick Reference Fact Sheet. EPA742-F-96-001.
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Getting Started—Integrating Pollution Prevention
Resources (cent.)
U.S. EPA. 1996. Profiting from Waste Reduction in Your Small Business. EPA742-B-88-100.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Paints and Coatings. EPA600-S-95-009.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Bourbon Whiskey. EPA600-S-95-010.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Automotive Battery Separators. EPA600-S-95-011.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Automotive Lighting Equipment and Accessories. EPA600-S-95-012.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Locking Devices. EPA600-S-95-013.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Combustion Engine Piston Rings. EPA600-S-95-015.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Metal Fasteners.EPA600-S-95-016.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Stainless Steel Pipes and Fittings. EPA600-S-95-017.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Outboard Motors. EPA600-S-95-018.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Electroplated Truck Bumpers. EPA600-S-95-019.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Printed Circuit
Board Plant.EPA600-S-95-020.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Folding Paperboard Cartons. EPA600-S-95-021.
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Getting Started—Integrating Pollution Prevention
Resources (cont.)
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Rebuilt Industrial Crankshafts. EPA600-S-95-022.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Pressure-sensitive Adhesive Tape. EPA600-S-95-023.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Wooden Cabinets. EPA600-S-95-024.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Power Supplies. EPA600-S-95-025.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Food Service Equipment. EPA600-S-95-026.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Metal Parts
Coater. EPA600-S-95-027.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Gear Cases for Outboard Motors. EPA600-S-95-028.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Electrical Load Centers. EPA600-S-95-029.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Pharmaceuticals. EPA600-S-95-030.
U.S. EPA. 1995. Environmental Research Brief: Pollution Prevention Assessment for a Manufacturer of
Aircraft Landing Gear. EPA600-S-95-032.
U.S. EPA. 1995. EPA Standards Network Fact Sheet: Role of Voluntary Standards. EPA741-F-95-005.
U.S. EPA. 1995. Introduction to Pollution Prevention: Training Manual. EPA742-B-95-003.
U.S. EPA. 1995. Recent Experience in Encouraging the Use of Pollution Prevention in Enforcement
Settlements: Final Report. EPA300-R-95-006.
U.S. EPA. 1995. Recycling Means Business. EPA530-K-95-005.
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Getting Started—Integrating Pollution Prevention
Resources (cent.)
U.S. EPA. 1994. Final Best Demonstrated Available Technology (BDAT) Background Document for
Universal Standards, Volume B: Universal Standards for Wastewater forms of Listed Hazardous Wastes,
Section 5, Treatment Performance Database. EPA530-R-95-033.
U.S. EPA. 1994. Review of Industrial Waste Exchanges. EPA530-K-94-003.
U.S. EPA. 1993. Guidance Manual for Developing Best Management Practices. EPA833-B-93-004.
U.S. EPA. 1993. Primer for Financial Analysis of Pollution Prevention Projects. EPA600-R-93-059.
U.S. EPA. 1992. Facility Pollution Prevention Guide. EPA600-R-92-008.
U.S. EPA. 1992. Practical Guide to Pollution Prevention Planning for the Iron and Steel Industries.
EPA742-B-92-100
U.S. EPA. 1991. Pollution Prevention Strategy. EPA741-R-92-001.
U.S. EPA. 1991. Treatment Technology Background Document; Third Third; Final. EPA530-SW-90-
059Z.
U.S. EPA. 1990. Guide to Pollution Prevention: Printed Circuit Board Manufacturing Industry. EPA625-
7-90-007
U.S. EPA. 1990. Waste Minimization: Environmental Quality with Economic Benefits. EPA530-SW-90-
044.
U.S. EPA. 1989. Treatment Technology Background Document; Second Third; Final. EPA530-SW-89-
048A.
3-18
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Part i
Getting Started
Chapter 4
Considering the Site
-------
Contents
[.General Siting Considerations
A. Floodplains 4~3
B. Wetlands 4~6
4 10
C. Active Fault Areas
4 12
D. Seismic Impact Zones
E. Unstable Areas - 4 ' 14
4 18
E Airport Vicinities
4 1Q
G. Wellhead Protection Areas
II. Buffer Zone Considerations
A. Recommended Buffer Zones 4 " 21
B. Additional Buffer Zones 4 ' 22
III. Local Land Use and Zoning Considerations 4 " 23
IV. Environmental Justice Considerations 4 " 23
Considering the Site Activity List 4 " 25
4-27
Resources..!
Appendix: State Buffer Zone Considerations , - - 4 ' 30
Tables:
Table 1: Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions 4- 12
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Getting Started—Considering the Site
Considering the Site
This chapter will help you:
• Become familiar with environmental, geological, and manmade fea-
tures that influence siting decisions.
• Identify nearby areas or land uses that merit buffer zones and place
your unit an appropriate distance from them.
• Comply with local land use and zoning restrictions, including any
amendments occurring during consideration of potential'sites.
• Understand existing environmental justice issues as you consider a
new site.
• Avoid siting a unit in hydrologic or geologic problem areas, without
first designing the unit to address conditions in those areas.
any hydrologic and geologic
settings can be effectively uti-
lized for protective waste
management. There are,
r however, some hydrologic
and geologic conditions that are best avoided
all together if possible. If they cannot be
avoided, special design and construction pre-
cautions can minimize risks. Floodplains,
This chapter will help address the follow-
ing questions:
• What types of sites need special consid-
eration?
• How will I know whether my waste
management unit is in an area requir-':
ing special consideration? :. ••-•':•
• Why should I be concerned about sit-
ing a waste management unit in such-
areas? . .
• What actions can I take if I plan to site
a unit in these areas?
earthquake zones, unstable soils, and areas at
risk for subsurface movement need to be
taken into account just as they would be
when siting and constructing a manufactur-
ing plant or home. Catastrophic events asso-
ciated with these locations could seriously
damage or destroy a waste management unit,
release contaminants into the environment,
and add substantial expenses for cleanup,
repair, or reconstruction. If problematic site
conditions cannot be avoided, engineering
design and construction techniques can
address some of the concerns raised by locat-
ing a unit in these areas.
Many state, local, and tribal governments
require buffer zones between waste manage-
ment units and other nearby land uses. Even
if buffer zones are not required, they can still
provide benefits now and in the future. Buffer
zones provide time and space to contain and
remediate accidental releases before they
reach sensitive environments or sensitive
populations. Buffer zones also help maintain
good community relations by reducing dis-
ruptions associated with noise, traffic, and
4-1
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Getting Started—Considering the Site
wind-blown dust, often the source of serious
neighborhood concerns.
In considering impacts on the surrounding
community, it is important to understand
whether the community, especially one with a
large minority and low income population,
already faces significant environmental
impacts from existing industrial activities. You
should develop an understanding of the com-
munity's current environmental problems and
work together to develop plans that can
improve and benefit the environment, the
community, the state, and the company.
How should a waste
management unit site
assessment begin?
In considering whether to site a new waste
management unit or laterally expand an exist-
ing unit, certain factors will influence the sit-
ing process. These factors include land
availability, distance from waste generation
points, ease of access, local climatic condi-
tions, economics, environmental considera-
tions, local zoning requirements, and potential
impacts on the community. As prospective
sites are identified, you should become famil-
iar with the siting considerations raised in this
chapter. Determine how to address concerns at
each site to minimize a unit's adverse impacts
on the environment in addition to the environ-
ment's adverse impacts on the unit. You should
choose the site that best balances protection of
human health and the environment with oper-
ational goals. In addition to considering the
issues raised in this chapter, you should check
with state and local regulatory agencies early
in the siting process to identify other issues
and applicable restrictions.
Another factor to consider is whether there
are any previous or current contamination
problems at the site. It is recommended that
potential sites for new waste management
units be free of any contamination problems.
An environmental site assessment (ESA) may
be required prior to the disturbance of any
land area or before property titles are trans-
ferred. An ESA is the process of determining
whether contamination is present on a parcel
of property. You should check with the EPA
regional office and state or local authorities to
determine if there are any ESA requirements
prior to siting a new unit or expanding an
existing unit. If there are no requirements,
you might want to consider performing an
ESA in order to ensure that there are no cont-
amination problems at the site.
Many companies specialize in site screening,
characterization, and sampling of different
environmental media (i.e., air, water, soil) for
potential contamination. A basic ESA (often
referred to as the Phase I Environmental Site
Assessment process) typically involves
researching prior land use, deciding if sam-
pling of environmental media is necessary
based on the prior activities, and detennining
contaminate fate and transport if contamina-
tion has occurred. Liability issues can arise if
the site had contamination problems prior to
construction or expansion of the waste man-
agement unit. Information on the extent of
contamination is needed to quantify cleanup
costs and determine the cleanup approach.
Cleanup costs can represent an additional,
possibly significant, project cost when siting a
waste management unit.
As discussed later in this chapter, you will
also need to consider other federal laws and
regulations that could affect siting. For exam-
ple, the Endangered Species Act (16 DSC :
Sections 1531 et seq.) provides for the desig-
nation and protection of threatened or endan-
gered wildlife, fish, and plant species, and
ensures the conservation of the ecosystems on
which such species depend. It is the responsi-
bility of the facility manager to check with
and obtain a Section 10 permit from the
Secretary of the Interior if the construction or
operation of a waste management unit might
potentially impact any endangered or threat-
4-2
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Getting Started—Considering the Site
ened species or its critical habitat. Thus, you
might not be able to site a new waste man-
agement unit in an area where endangered or
threatened species live, or expand an existing
unit into such an area. As another example,
the National Historic Preservation Act (16
USC Sections 470 et seq.) protects historic
sites and archaeological resources. The facility
manager of a waste management unit should
be aware of the properties listed on the
National Register of Historic Properties. The
facility manager should consult with the state
historic preservation office to ensure that the
property to be used for a new unit or lateral
expansion of an existing unit will not impact
listed historic properties, or sites with archeo-
logical significance. Other federal laws or
statutes might also require consideration. It is
the ultimate responsibility of the facility
owner or manager to comply with the
requirements of all applicable federal and
state statutes when siting a waste manage-
ment unit.
Additional factors, such as proximity to
other activities or sites that affect the environ-
ment, also might influence siting decisions.
To determine your unit's proximity to other
facilities or industrial sites, you can utilize
EPAs Envirofacts Warehouse. The Envirofacts
Web site at provides users with access to sev-
eral EPA databases that will provide you with
information about various errnmonarental
activities including toxic chemical releases,
water discharges, hazardous waste handling
processes, Superfund status, and air releases.
The Web site allows you to search one .data-
base or several databases at a time about a
specific location or facility. You can also cre-
ate maps that display environmental informa-
tion using the "Enviromapper" application
located at . Enviromapper allows users to
map different types of environmental infor-
mation, including the location of drinking
water supplies, toxic and air releases, haz-
ardous waste sites, water discharge permits,
and Superfund sites at the national, state, and
county levels.
EPA's Waste Management—Facility Siting
Application is a powerful new Web-based
tool that provides assistance in locating waste
management facilities. The tool allows the
user to enter a ZIP code; city and state; or lat-
itude and longitude to identify the location of
fault lines, flood planes, wetlands, and karst
terrain in the selected area. The user also can
use the tool to display other EPA regulated
facilities, monitoring sites, water bodies, and
community demographics. The Facility Siting
Application can be found at .
I. General Siting
Considerations
Examining the topography of a site is the
first step in siting a unit. Topographic infor-
mation is available from the U.S. Geological
Survey (USGS), the Natural Resources
Conservation Service (NRCS)1, the states geo-
logical survey office or environmental regula-
tory agency, or local colleges and universities.
Remote sensing data or maps from these orga-
nizations can help you determine whether
your prospective site is located in any'of the
areas of concern discussed in this section.
USGS maps can be downloaded or ordered
from their Web site at .
Also, the University of Missouri-Rolla main-
tains a current list of state geological survey
offices on its library's Web site at
.
A. Floodplains
A floodplain is a relatively flat, lowland
area adjoining inland and coastal waters. The
This agency of the U.S. Department of Agriculture was formerly known as the Soil Conservation
Service (SCS).
4-3
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Getting Started—Considering the Site
Flood waters overflowed from the
Mississippi River (center) into its floodplain
(foreground) at Quincy, Illinois in the 1993
floods that exceeded 100-year levels in parts
of the Midwest.
100-year floodplain—the area susceptible to
inundation during a large magnitude flood
with a 1 percent chance of recurring in any
given year—is usually the floodplain of con-
cern for waste management units. You should
determine whether a candidate site is in a
100-year floodplain. Siting a waste manage-
ment unit in a 100-year floodplain increases
the likelihood of floods inundating the unit,
increases the potential for damage to liner sys-
tems and support components (e.g., leachate
collection and removal systems or other unit
structures), and presents operational concerns.
This, in turn, creates environmental and
human health and safety concerns, as well as
legal liabilities. It can also be very costly to
build a unit to withstand a 100-year flood
without washout of waste or damage to the
unit, or to reconstruct a unit after such a
flood. Furdier, locating your unit in a flood-
plain can exacerbate the damaging effects-of a
flood, both upstream and downstream, by
reducing the temporary water storage capacity
of the floodplain. As such, it is preferable to
locate potential sites outside the 100-year
floodplain.
How is it determined if a
prospective site is in a 100-year
floodplain?
The first step in determining whether a
prospective site is located in a 100-year flood-
plain is to consult with the Federal Emergency
Management Agency (FEMA). FEMA has pre-
pared flood hazard boundary maps for most
regions. If a prospective site does not appear
to be located in a floodplain, further explo-
ration is not necessary. If uncertainty exists as
to whether the prospective site might be in a
floodplain, several sources of information are
available to help make this determination.
More detailed flood insurance rate maps
(FIRMs) can be obtained from FEMA. FIRMs
divide floodplain areas into three zones: A, B,
and C. Class A zones are the most susceptible
to flooding while class C zones are the least
susceptible. FIRMs can be obtained from
FEMA's Web site at ).
FEMA also publishes The National Flood
Insurance Program Community Status Book
which lists communities with flood insurance
rate maps or floodway maps. Floodplain maps
can also be obtained through the US
Geological Survey (USGS); National Resources
Conservation Service (NRCS); the Bureau of
Land Management; the Tennessee Valley
Authority; and state, local, and tribal agencies.2
Note that river channels shown in flood-
plain maps can change due to hydropower or
flood control projects. As a result, some flood-
plain boundaries might be inaccurate. If you
suspect this to be the case, consult recent aeri-
al photographs to determine how river chan-
nels have been modified.
Copies of flood maps from FEMA are available at Map Service Center, P.O. Box 1038, Jessup, MD 20794-
1038, by phone 800 358-9616, or the Internet at .
4-4
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Getting Started—Considering the Site
If maps cannot be obtained, and
a potential site is suspected to be
located in a floodplain, you can
conduct a field study to 'delineate
the floodplain and determine the
floodplain's properties. To perform
a delineation, you can draw on
meteorological records and physio-
graphic information, such as exist-
ing and planned watershed land
use, topography, soils and geo-
graphic mapping, and aerial photo-
graphic interpretation of land
forms. Additionally, you can use
the U.S. Water Resources Council's
methods of determining flood
potential based on stream gauge
records, or you can estimate the
peak discharge to approximate the
probability of exceeding the 100-
year flood. Contact the USGS,
Office of Surface Water, for addi-
tional information concerning
these methods.3
What can be done if a
prospective site is in a
floodplain?
If a new waste management unit
or lateral expansion will be sited in
a floodplain, design the unit to pre-
vent the washout of waste, avoid sig-
FEMA provides flood maps like this one for most floodplains
Source: FEMA/Q3 Flood Data Users Guide'
nificant alteration of flood flow, and maintain
"the temporary storage capacity of the flood- '
plain; Engineering models can be used to
estimate a floodplain's storage capacity and
floodwater flow velocity. The U.S. Army
Corps of Engineers (USAGE) Hydrologic
Engineering Center has developed several
computer models for simulating flood prop-
erties.4 The models can predict how a waste .•
management unit sited in a floodplain can
affect its storage capacity and can also simu-
late flood control structures and sediment'
transport. If a computer model predicts that
placement of the waste management unit in
the floodplain raises the base flood level by
more than 1 foot, the unit might alter the
storage capacity of the floodplain. If design-
tog a new unit, you should site it to minimize
these effects. The impact of your unit's loca-
tion on the speed and flow of flood waters
determines the likelihood of waste washout.
To quantify this, estimate the shear stress on
the unit's support components caused by the
impinging flood waters at the depth, velocity,
Information on stream gaging and flood forecasting can be obtained from the USGS, Office of Surface
Water, at 413 National Center, Reston, VA 22092, by phone 703 648-5977, or the Internet at
. ' . •
The HEC-1, HEC-2, HEC-5, and HEC-6 software packages are available free of charge through the
USAGE Web site at .
4-5
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Getting Started—Considering the Site
Knowing the behavior of waters at their
peak flood level is important for determin-
ing whether waste will wash out.
and duration associated with the peak (i.e.,
highest) flow period of the flood.
While these methods can help protect
your unit from flood damage and washout,
be aware that they can further contribute to a
decrease in the water storage and flow capac-
ity of the floodplain. This, in turn, can raise
the level of flood waters not only in your area
but in upstream and downstream locations,
increasing the danger of flood damage and
adding to the cost of flood control programs.
Thus, serious consideration should be given
to siting a waste management unit outside a
100-year floodplain.
B. Wetlands
Wetlands, which include swamps, marshes,
and bogs, are vital and delicate ecosystems.
They are among the most productive biologi-
cal communities on earth and provide habitat
for many plants and animals. The U.S. Fish
and Wildlife Service estimates that up to 43
percent of all endangered or threatened
species rely on wetlands for their survival.5
Riprap (rock cover) reduces stream channel erosion (left) and gabions (crushed rock encased
in wire mesh) help stabilize erodible slopes (right).
Sources: U.S. Department of the Interior, Office of Surface Mining (left); The Construction
Site—A Directory To The Construction Industry (right).
5 From EEAs Wedands Web site, Values and Functions of Wetlands factsheet, .
4-6
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Getting Started—Considering the Site
For regulatory purposes under the Clean
Water Act, wetlands are defmed'as areas
"that are mundated or saturated Tjy sur-
face or ground water, at a^frequency and
duration sufficient tofsuppbrt, and that
under normal ^circumstances do support, <
a prevalence of vegetation typically"Jdapt-
ed for life m saturated-'soil conditions "
' * , ' „
40 Code of Federal Regulations (CFR) 232 2(r)
, Wetlands protect water quality by assimilating
water pollutants, removing sediments contain-
ing heavy metals, and recharging ground-
water supplies. Wetlands also prevent
potentially extensive and costly floods by tem-
porarily storing flood waters and reducing
their velocity. These areas also offer numerous
recreational opportunities.
Potential adverse impacts associated with
locating your unit in a wetland include dewa-
tering the wetland (i.e., causing removal or
drainage of water), contaminating the wet-
land, and causing loss of wetland acreage.
Damage could also be done to important wet-
land ecosystems by destroying their aesthetic
qualities and diminishing wildlife breeding
and feeding opportunities. Siting in a wetland
increases the potential for damage to your
unit, especially your liner system and struc-
tural components, as a result of ground set-
tlement, action of the high water table, and
flooding. Alternatives to siting a waste man-
agement unit in a wetland area should be
given serious consideration based upon
Section 404 requirements in the Clean Water
Act (CWA) as discussed below.
If a waste management unit is to be sited in
a wetland area, the unit will be subject to
additional regulations. In particular, Section
404 of die Clean Water Act (CWA) authorizes
the Secretary of the Army, acting through the
Chief of Engineers, to issue permits for the
discharge of dredged or fill material into wet-
lands and other waters of the United States.6
Activities in waters of the United States regu-
lated under diis permitting program include
"placement of fill material for construction or
maintenance of any liner, berm, or other
infrastructure associated with solid waste
landfills," as well as fills for development,
water resource projects, infrastructure
improvements, and conversion of wetlands to
uplands for farming and forestry (40 CFR
Section 232.2—definition of "discharge of fill
material"). EPA regulations under Section 404
(33 United States Code Section 1344) stipu-
lates that no discharge of dredged or fill mate-
rial can be permitted if a practicable
alternative exists that is less damaging to the
aquatic environment or if the nations waters
would be significantly degraded. Therefore, in
Different types of wetlands: spruce bog (left) and eco pond in the Florida Everglades (right).
For the full text of the Clean Water Act, including Section 404, visit the U.S. House of Representatives
Internet Law Library Web site at , under Title 33, Chapter 26.
4-7
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Getting Started—Considering the Site
compliance with the guidelines established
under Section 404, all permit applicants must:
• Take steps to avoid wetland impacts
where practicable.
• Minimize impacts to wetlands where
they are unavoidable.
Compensate for any remaining,
unavoidable impacts by restoring
creating wetlands.
or
The EPA and USAGE jointly administer a
review process to issue permits for regulated
activities. For projects with potentially signifi-
cant impacts, an individual permit is usually
required. For most discharges with only mini-
mal adverse effects, USAGE may allow appli-
cants to comply with existing general
permits, which are issued on a nationwide,
regional, or statewide basis for particular
activity categories as a means to expedite the
permitting process. In making permitting
decisions, the agencies will consider other
federal laws that might restrict placement of
waste management units in wetlands. These
include the Endangered Species Act; the
Migratory Bird Conservation Act; the Coastal
Zone Management Act; the Wild and Scenic
Rivers Act; the Marine Protection, Research
and Sanctuaries Act; and the National •
Historic Preservation Act.
How is it determined if a
prospective site is in a wetland?
As a first step, determine if the prospective
site meets the definition of a wetland. If the
prospective site does not appear to be a wet-
land, then no further exploration is necessary.
If it is uncertain whedier the prospective site
is a wetland, then several sources are avail-
able to help you make this determination and
define the boundaries of the wetland.
Although this can be a challenging process, it
will help you avoid future liability since fill-
ing a wetland without the appropriate federal,
state, Or local permits would be a violation of
many laws. It might be possible to learn the
extent of wetlands without performing a new
delineation, since many wetlands have previ-
ously been mapped. The first step, therefore,
should be to determine whether wetlands
information is available for your area. :
At the federal level, four agencies are prin-
cipally involved with wetlands identification
and delineation: USAGE, EPA, the U.S. Fish
and Wildlife Service (FWS), and National
Resource Conservation Service (NRCS). EPA
also has a Wetlands Information Hotline (800
832-7828) and a wetlands Web site at which provides
information about EPAs wetlands program;
facts about wetlands; the laws, regulations,
and guidance affecting wetlands; and science,
education, and information resources for wet-
lands. The local offices of NRCS (in agricul-
tural areas) or regional USAGE Engineer
Divisions and Districts might know whether
wetlands in the vicinity of the potential site
have already been delineated.
Additionally, FWS maintains the National
Wetlands Inventory (NWI) Center,7 from
which you can obtain wetlands mapping for
much of the United States. This mapping,
however, is based on aerial photography,
which is not reliable for specific field deter-
minations. If you have recently purchased
your site, you also might be able to find out
from the previous property owner whether
any delineation has been completed that
might not be on file with these agencies. Even
if existing delineation information for the site
is found, it might still be prudent to contact a
qualified wetlands consultant to verify the
wetland boundaries, especially if the delin-
eation is not a field determination or is more
than a few years old.
If the existence of a wetland is uncertain,
you should obtain a wetlands delineation.
4-8
To contact NWI, write to National Wetlands Inventory Center, 9720 Executive Center Drive, Suite 101,
Monroe Building, St. Petersburg, FL 33702, call 727 570-5400, or fax 727 570-5420. For additional
information online or to search for maps of your area, visit: .
-------
Getting Started—Considering the Site
This procedure should be performed only by
an individual with experience in performing a
wetlands delineation8 using standard delin-
eation procedures or applicable state or local
delineation standards. The delineation proce-
dure, with which you should become familiar
before hiring a delineator, involves collecting
maps, aerial photographs, plant data, soil sur-
veys, stream gauge data, land use data, and
other information. Note that it is mandatory
that wetlands delineation for CWA Section
404 permitting purposes be conducted in
accordance with the 1987 U.S. Army Corps of
Engineers Wetlands Delineation Manual9
(USAGE, 1991). The manual provides guide-
lines and methods for determining whether
an area is a wetland for purposes of Section
404. A three-parameter approach for assess-
ing the presence and location of hydrophytic
vegetation (i.e., plants that are adapted for life
in saturated soils), wetland hydrology, and
hydric soils is discussed.
What can be done if a
prospective site is in a wetland?
Before constructing a waste management
unit in a wetland area, consider whether you
can locate the unit elsewhere. If an alternative
location can be identified, strongly consider
pursuing such an option, as required by
Section 404 of the CWA. Because wetlands
are important ecosystems that should be pro-
tected, identification of practicable location
alternatives is a necessary first step in the sit-
ing process. Even if no viable alternative loca-
NWI wetland resource maps like this one show the locations of various different types of
wetlands and are available for many areas.
Source: NWI web site, sample GIS Think Tank maps page, .
8 Currently, there is no federal certification program. In March 1995, USACE proposed standards for a
Wetlands Delineator Certification Program (WDCP), but the standards have not been finalized. If the
WDCP standards are finalized and implemented, you should use WDCP-certified wetland consultants.
9 The 1987 .manual can be ordered from the National Technical Information Service (NTIS) at 703 605-
6000 or obtained online at .
4-9
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Getting Started—Considering the Site
tions are identified, it might be beneficial to
keep a record of the alternatives investigated,
noting why they were not acceptable. Such
records might be useful during the interac-
tion between facilities, states, and members of
the community.
If no alternatives are available, you should
consult with state and local regulatory agen-
cies concerning wetland permits. Most states
operate permitting programs under the CWA,
and state authorities can guide-you through
the permitting process. To obtain a permit,
the state might require diat the unit facility
manager assess wetland impacts and then:
• Prevent contamination from leachate
and runoff.
• Minimize dewatering effects.
• Reduce the loss of wetland acreage.
• Protect the waste management unit
against settling.
C. Active Fault Areas
Faults occur when stresses in a geologic
material exceed its ability to withstand these
forces. Areas surrounding faults are subject to
earthquakes and ground failures, -such as
landslides or soil liquefaction. Fault move-
ment can directly weaken or destroy-struc-
tures, or seismic activity associated with
faulting can cause damage to structures •
through vibrations. Structural damage to the .
waste management unit could result in the
release of contaminants. In addition, fault
movement might create avenues to ground-
water supplies, increasing the risk of ground-
water contamination. . ".-..,•
Liquefaction is another common problem
encountered in areas of seismic activity. The
vibrating motions caused by an earthquake
tend to rearrange the sand grains in soils. If
the grains are saturated, the saturated .granu-
lar material turns into a viscous fluid, a
process referred to as liquefaction. This
diminishes the bearing capacity of the soils
and can lead to foundation and slope failures.
To avoid these hazards, do not build or
expand a unit within 200 feet of an active
fault. If it is not possible to site a unit more
than 200 feet from an,active fault, you should
design the unit to withstand the potential
ground movement associated with the fault
area. A fault is considered active if there has
been movement along it within the last 10,000
to 12,000 years.
How is it determined if a
prospective site is in a fault area?
A series of USGS maps, Preliminary Young
Fault Maps, Miscellaneous Field Investigation
916, identifies active faults.lq These maps,
however, might not be completely accurate •
due to recent shifts in fault lines. If a prospec-
tive site is well outside the 200 foot area of
concern, no fault area considerations exist. If
it is unclear how close a prospective site is to
an active fault, further evaluation will be nec-
essary. A geologic reconnaissance of the site
and surrounding areas can be useful in verify-
ing that active faults do not exist at the site.
If a prospective site is in an area known or
suspected to be prone to faulting, you should
conduct a fault characterization to determine
if the site is near a fault. A characterization
includes identifying linear features diat sug-
gest the presence of faults within a 3,000-foot
radius of the site. Such features might be
.shown or described on maps, aerial pho-
tographs," logs, reports, scientific literature,
or'insurance claim reports, or identified by a
detailed field reconnaissance of the area.
If the characterization study reveals faults
within 3,000 feet of the proposed unit or lat-
4-10
10 Information about ordering these maps is available by calling 888 ASK-USGS or 703 648-6045. -
" The National Aerial Photographic Program (NAPP) and the National High Altitude Program (NHAP),
both administered by USGS, are sources "of aerial photographs. To order from USGS, call 605 594-
6151. For more information, see . Local aerial photography firms and
surveyors are also good sources of information.
-------
Getting Started—Considering the Site
In this aerial view, the infamous San Andreas
fault slices through the Carrizo Plain east of
San Luis Obispo, California.
Source: USGS.
eral expansion, you should conduct further
investigations to determine whether any of
the faults are active within 200 feet of the
unit. These investigations can involve drilling
and trenching the subsurface to locate fault
zones and evidence of faulting. Perpendicular
trenching should be used on any fault within
200 feet of the proposed unit to examine the
seismic epicenter for indications of recent
movement. .
What can be done if a prospective
site is in a fault area?
If an active fault exists on the site where
the unit is planned, consider placing the unit
200 feet back from the fault area. Even with
such setbacks, only place a unit in a fault area
if it is possible to ensure that no damage to
the unit's structural integrity would result. A
setback of less than 200 feet might be ade-
quate if ground movement would not damage
the unit.
If a lateral expansion or a new unit will be
located in an area susceptible to seismic activ-
ity, there are two particularly important issues
to consider: horizontal acceleration and
movement affecting side slopes. Horizontal
acceleration becomes a concern when a loca-
tion analysis reveals that the site is in a zone
with a risk of horizontal acceleration in the
range of 0.1 g to 0.75 g (g = acceleration of
gravity). In these zones, the unit design
should incorporate measures to protect the
unit from potential ground shifts. To address
side slope concerns, you should conduct a
seismic stability analysis to determine the
most effective materials and gradients for pro-
tecting the unit's slopes from any seismic
instabilities. Also, design the unit to with-
stand the impact of vertical accelerations.
If the unit is in an area susceptible to liq-
uefaction, you should consider ground
improvement measures. These measures
include grouting, dewatering, heavy tamping,
and excavation. See Table 1 for examples of
techniques that are currently used.
Additional engineering options for fault
areas include the use of flexible pipes for
runoff and leachate collection, and redundant
containment systems. In the event of founda-
tion soil collapse or heavy shifting, flexible
runoff and leachate collection pipes—along
with a bedding of gravel or permeable materi-
al—can absorb some of the shifting-related
stress to which the pipes are subjected. Also
consider a secondary containment measure,
such as an additional liner system. In earth-
quake-like conditions, a redundancy of this
nature might be necessary to prevent contam-
ination of the surrounding area if the primary
liner system fails.
4-11
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Getting Started—Considering the Site
Table 1
Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions
Method \ Principle Most Suitable Soil Applications f
i --- :"- -. Conditions/Types .....;•--. -I ;
- ! j - - • .- "' - -- - ' : '- T - - •'..--."'•'-•• I ;.'••.-='• .-- / -I'."
Blasting
Vibrocompaction
Compaction piles
Displacement and
compaction grout
Mix-in-place piles
and wafls
Heavy tamping
(dynamic
compaction)
Shock waves and vibrations cause
limited liquefaction, displacement,
remolding, and setdement to higher
density.
Densification by vibration and
compaction of backfill material of sand
or gravel.
Densification by displacement of pile
volume and by vibration during driving;
increase in lateral effective earth
pressure.
Highly viscous grout acts as radial
hydraulic jack when pumped in under
high pressure.
Lime, cement, or asphalt introduced
through rotating auger or special in-
place mixer.
Repeated application of high- intensity
impacts at surface.
Saturated, clean sands; partly
saturated sands and silts after
flooding.
Cohesionless soils with less
than 20 percent fines.
Loose sandy soils; partly
saturated clayey soils; loess.
All soils.
Sand, silts, and clays; all soft
or loose inorganic soils.
Cohesionless soils best; other
types can also be improved.
Induce liquefaction in controlled and
limited stages and increase relative density
to potentially nonliquefiable range.
Induce liquefaction in controlled and
limited stages and increase relative density
to nonliquefiable condition. The dense
column of backfill provides (a) vertical
support, (b) drainage to relieve pore water
pressure, and (c) shear resistance in hori-
zontal and inclined directions. Used to
stabilize slopes and strengthen potential
failure surfaces.
Useful in soils with fines. Increases relative
density to nonliquefiable condition.
Provides shear resistance in horizontal and
inclined directions. Used to stabilize
slopes and strengthen potential failure
surfaces.
Increase in soil relative density and
horizontal effective stress. Reduce
liquefaction potential. Stabilize the ground
against movement.
Slope stabilization by providing shear
resistance in horizontal and inclined
directions, which strengthens .potential
failure surfaces or slip circles. A wall could
be used to confine an area of liquefiable
soil.
Suitable for some soils with fines; usable
above and below water. In Cohesionless
soils, induces liquefaction in controlled
and limited stages and increases relative
density to potentially nonliquefiable range.
Source: RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste Landfill Facilities. (EPA, 1995c).
D. Seismic Impact Zones
A seismic impact zone is an area having a
2 percent or greater probability that the maxi-
mum horizontal acceleration caused .by an
earthquake at the site will exceed 0.1 g in 50
years. This seismic activity can damage
leachate collection and removal systems, leak
detection systems, or other unit structures
through excessive bending, shearing, tension,
and compression. If a unit's structural compo-
nents fail, leachate can contaminate sur-
rounding areas. Therefore, for safety reasons,
it is recommended that a unit not be located
in a seismic impact .zone. If a unit must be
sited in a seismic impact zone, the unit
should be designed to -withstand earthquake-
related hazards, such as landslides, slope fail-
ures, soil compaction, ground subsidence,
and soil liquefaction.
Additionally, if you build a unit in a seis-
mic impact zone, avoid rock and soil types
that are especially vulnerable to earthquake
shocks. These include very steep slopes of
weak, fractured, and brittle rock or unsaturat-
ed loess,12 which are vulnerable to transient
shocks caused by tensional faulting. Avoid
12 Loess is a wind-deposited, moisture-deficient silt that tends to compact when wet.
4-12
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Getting Started—Considering the Site
loess and saturated sand as well, because seis-
mic shocks can liquefy them, causing sudden
collapse of structures. Similar effects are possi-
ble in sensitive cohesive soils when natural
moisture exceeds the soil's liquid limit. For a
discussion of liquid limits, refer to the "Soil
Properties" discussion in Chapter 7, Section B
- Designing and Installing Liners. Earthquake-
induced ground vibrations can also compact
loose granular soils. This could result in large
uniform or differential settlements at the
ground surface.
How is it determined if a
prospective site is in a seismic
impact zone?
If a prospective site is in an area with no
history, of earthquakes, then seismic impact
zone considerations might not exist. If it is
unclear whether the area has a history of seis-
mic activity, then further evaluation will be
necessary. As a first step, consult the USGS
field study map series MF-2120, Probabilistic
Earthquake Acceleration and Velocity Mapsfor
the United States and Puerto Rico." These maps
provide state- and county-specific information
about seismic impact zones. Additional infor-
mation is available from the USGS National
Earthquake Information Center (NEIC),1+
which maintains a database of known earth-
quake and fault zones. Further information
concerning the USGS National Seismic Hazard
Mapping Project can be accessed at . USGS's Web site also
allows you to find ground motion hazard
parameters (including peak ground accelera-
tion and spectra acceleration) for your site by
entering a 5 digit ZIP code
, or a latitude-longitude coordinate
pair . The USGS Web site explains how
these values can be used to determine the
probability of excedance for a particular level
of ground motion at your site. This can help
you determine if the structural integrity of the
unit is susceptible to damage from ground
motion.
For waste management unit siting purpos-
es, use USGS' recently revised Peak
Acceleration (%g) with 2 % Probability of
Exceedance in 50 Years maps available at
. It is important to note that
ground motion values having a 2 percent
probability of exceedance in 50 years are
approximately the same as those having. 10
percent probability of being exceeded in 250
years. According to USGS calculations, the
annual exceedance probabilities of these two
differ by about 4 percent (for a more complete
discussion visit: ).
If a site is or might be in a seismic impact
zone, it is useful to analyze, the effects of seis-
mic activity on soils in and under the unit. .
Computer software programs are available that
can evaluate soil liquefaction potential
(defined in Section C of this chapter). LIQ-
UFAC, a software program developed by the
Naval Facilities Engineering Command in
Washington, DC, can calculate safety factors
for each soil layer in a given soil profile and
the corresponding one dimensional settle-
ments due to earthquake loading.
What can be done if a
prospective site is in a seismic
impact zone?
If a waste management unit cannot be sited
outside a seismic impact zone, structural com-
ponents of the unit—including liners, leachate
collection and removal systems, and surface-
water control systems—should be designed to
resist the earthquake-related stresses expected
in the local soil. You should consult profes-
sionals experienced in seismic analysis and
13 For information on ordering these maps, call 888 ASK-USGS, write to USGS Information Services, Box
25286, Denver, CO 80225, or fax 303 202-4693. Online information is available at
.
14 To contact NEIC, call 303 273-8500, write to United States Geological Survey, National Earthquake
Information Center, Box 25046, DFC, MS 967, Denver, CO 80225, fax 303 273-8450, or e-mail
sedas@neic.cr.usgs.gov. For online information, visit: .
4-13
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Getting Started—Considering the Site
design to ensure that your unit is designed
appropriately To determine the potential
effects of seismic activity on a structure, the
seismic design specialist should evaluate soil
behavior with respect to earthquake intensity.
This evaluation should account for soil
strength, degree of compaction, sorting (orga-
nization of the soil particles), saturation, and
peak acceleration of the potential earthquake.
After conducting an evaluation of soil
behavior, choose appropriate earthquake pro-
tection measures. These might include shal-
lower slopes, dike and runoff control designs
using conservative safety factors, and contin-
gency plans or backup systems for leachate
collection if primary systems are disrupted.
Unit components should be able to withstand
the additional forces imposed by an earth-
quake within acceptable margins of safety.
Additionally, well-compacted, cohesionless
embankments or reasonably flat slopes in
insensitive clay (clay that maintains its com-
pression strength when remolded) are less
likely to fail under moderate seismic shocks
(up to 0.15 g - 0.20 g). Embankments made
of insensitive, cohesive soils founded on
cohesive soils or rock can withstand even
greater seismic shocks. For earthen embank-
ments in seismic regions, consider designing
the unit with internal drainage and core
materials resistant to fracturing. Also, prior to
or during unit construction in a seismic
impact zone, you should evaluate excavation
slope stability to determine the appropriate
grade of slopes to minimize potential slip.
For landfills and waste piles, using shal-
lower waste side slopes is recommended, as
steep slopes are more vulnerable to slides
and collapse during earthquakes. Use fill
sequencing techniques that avoid concentrat-
ing waste in one area of the unit for an
extended period of time. This prevents waste
pile side slopes from becoming too steep and
unstable and alleviates differential loading of
the foundation components. Placing too
much waste in owe area of the unit can lead
to catastrophic shifting during an earthquake
or heavy seismic activity. Shifting of this
nature can cause failure of crucial system
components or of the unit in general.
In addition, seismic impact zones have
design issues in common with fault areas,
especially concerning soil liquefaction and
earthquake-related stresses. To address lique-
faction, consider employing the soil improve-
ment techniques described in Table 1.
Treating liquefiable soils in the vicinity of the
unit will improve foundation stability and
help prevent uneven settling or possible col-
lapse of heavily saturated soils-underneath or
near the unit.
To protect against earthquake-related
stresses, consider installing redundant liners
and special leachate collection and removal
system components, such as secondary liner
systems, composite liners, and leak detection
systems combined with a low permeability
soil layer. These measures function as back-
ups to the primary containment and collec-
tion systems and provide a greater margin of
safety for units during possible seismic stress-
es. Examples of special leachate systems
include high-strength, flexible materials for
leachate containment systems; geomembrane
liner systems underlying leachate contain-
ment systems; and perforated polyvinyl chlo-
ride or high-density polyethylene piping in a
bed of gravel or other permeable material.
E. Unstable Areas
Siting in unstable areas should be avoided
because these locations are susceptible to nat-
urally occurring or human-induced events or
forces capable of impairing the integrity of a
waste management unit. Naturally occurring
unstable areas include regions with poor soil
foundations, regions susceptible to mass
movement, or regions containing karst ter/
4-14
-------
Getting Started—Considering the Site
rain, which can include hidden sinkholes.
Unstable areas caused by human activity can
include areas near cut or fill slopes, areas
• with excessive drawdown of ground water,
and area's where significant quantities of oil
or natural gas,have.been.extracted. If it is
necessary to site a waste management unit in
an unstable area, technical and construction
techniques should be considered to mitigate
•against potential damage.
, The three primary types of failure that can
occur in an unstable area are settlement, loss
of bearing strength, and sinkhole collapse.
Settlement can result from soil compression if
your unit is, or will be located in, an unstable
area over a thick, extensive clay layer. The
unit's weight can force water from the com-
pressible clay, compacting it and allowing the
unit to settle. Settlement can increase as
waste volume increases and can result in
structural failure of the unit if it was not
properly engineered. Settlement beneath a
waste management unit should be assessed
and compared to the elongation strength and
flexibility properties of the liner and leachate
collection pipe system. Even small amounts
of settlement can seriously damage leachate
collection piping and sumps. A unit should
be engineered to minimize the impacts of set-
tlement if if is, or will be in an unstable area.
Loss of bearing strength is a failure mode
that occurs in soils that tend to expand and
rapidly settle or liquefy.' Soil contractions and
expansions ianlncrease the risk of leachate or
waste release. Another example of loss of bear-
ing strength-occurs >when excavation near the
. unit reduces the mass of,soil at the toe of the
"slope, thereby reducing the overall strength
-(resisting force) of the foundation soil.
Catastrophic collapse in the form of sink-
holes can occur in karst terrain. As water,
especially acidic water, percolates through
limestone, the soluble carbonate material dis-
solves, leaving cavities and caverns. Land
overlying caverns can collapse suddenly,
resulting in sinkholes that can be more than
100 feet deep and 300 feet wide.
How is it determined if a
prospective site is in an
unstable area?
If a stability assessment has not been per-
formed on a potential site, you should have a
qualified professional conduct one before
designing a waste management unit on the
prospective site. The qualified professional
should assess natural conditions, such as soil
geology and geomorphology, as well as
human-induced surface and subsurface fea-
tures or events that could cause differential
ground settlement. Naturally unstable condi-
tions can become more unpredictable and
destructive if amplified by human-induced
changes to the environment. If a unit is to be
built at an assessed site that exhibits stability
problems, tailor the design to account for any
instability detected. A stability assessment
typically includes the following steps:
Screen for expansive soils. Expansive
soils can lose their ability to support a foun-
dation when subjected to certain natural or
human-induced events, such as heavy rain or
explosions. Expansive soils usually are clay-
rich and, because of their molecular struc-
ture, tend to swell and shrink by taking up
and releasing water. Such soils include smec-
tite (montmorillonite group) and vermiculite
clays. In addition, soils rich in white alkali
(sodium sulfate), anhydrite (calcium sulfate),
or pyrite (iron sulfide) can also swell as water
content increases. These soils are more com-
mon in the arid western states.
Check for soil subsidence. Soils subject
to rapid subsidence include loesses, uncon-
solidated clays, and wetland soils. Unconsol-
idated clays can undergo considerable
compaction when oil or water is removed.
Similarly, wetland soils, which by their
4-15
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Getting Started—Considering the Site
Sinkholes, like this one that occurred just north of Orlando, Florida in 1981, are a risk of
development in Karst terrain. Left: aerial view (note baseball diamond for scale); right:
ground-level view. Photos courtesy of City of Winter Park, Florida public relations office.
nature are water-bearing, are also subject to
subsidence when water is withdrawn.
Look for areas subject to mass move-
ment or slippage. Such areas are often situ-
ated on slopes and tend to have rock or soil
conditions conducive to downhill sliding.
Examples of mass movements include
avalanches, landslides, and rock slides. Some
sites might require cutting or filling slopes
during construction. Such activities can cause
existing soil or rock to slip.
Search for karst terrain. Karst features
are areas containing soluble bedrock, such as
limestone or dolomite, that have been dis-
solved and eroded by water, leaving charac-
teristic physiographic features including
sinkholes, sinking streams, caves, large
springs, and blind valleys. The principal con-
cern with karst terrains is progressive or cata-
strophic subsurface failure due to the
presence of sinkholes, solution cavities, and
subterranean caverns. Karst features can also
hamper detection and control of leachate,
which can move rapidly through hidden con-
duits beneath the unit. Karst maps, such as
Engineering Aspects of Karst, Scale 1:7,50Q,000,
Map No. 38077-AW-NA-07M-00, produced by
the USGS15 and state specific geological maps
can be reviewed to identify karst areas.
Scan for evidence of excessive ground-
water drawdown or oil and gas extraction:
Removing underground water can increase
the effective overburden on the foundation
soils underneath the unit. Excessive draw-
down of water might cause settlement or
bearing capacity
failure on the
foundation soils.
Extraction of oil
or natural gas
can have similar
effects.
Investigate
the geotechnical
and geological
characteristics
of the site. It is
important to
establish soil
strengths and
other engineer-
ing properties. A
geotechnical
engineering con-
Subsidence, slippage, and
other kinds of slope failure
can damage structures.
4-16
15 For information on ordering this map, call 888 ASK-USGS, write USGS Information Services,
Box 25286, Denver, CO 80255, or fax 303 202-4693. Online information is available at
.
-------
Getting Started—Considering the Site
sultant can accomplish this by performing
standard penetration tests, field vane shear
tests, and laboratory tests. This information
will determine how large a unit you can safely
place on the site. Other soil properties to
examine include water content, shear
strength, plasticity, and grain size distribution.
Examine the liquefaction potential. It is
extremely important to ascertain the liquefaction
potential of embankments, slopes, and founda-
tion soils. Refer to Section C of this chapter for
more information about liquefiable soils.
What can be done if a
prospective site is in an
unstable area?
It is advisable not to locate or expand your
waste management unit in an unstable area. If
your unit is or will be located in such an area,
you should safeguard the structural integrity
of the unit by incorporating appropriate mea-
sures into the design. The integrity of the unit
might be jeopardized if this is not done.
For example, to safeguard the structural
integrity of side slopes in an unstable area,
reduce slope height, flatten slope angle, exca-
vate a bench in the upper portion of the slope,
or buttress slopes with compacted eardi or rock
fill. Alternatively, build retaining structures,
such as retaining walls or slabs and piles. Other
approaches include the use of geotextiles and
geogrids to provide additional strength, wick
and toe drains to relieve excess pore pressures,
grouting, arid vacuum and wellpoint pumping
to lower ground- water levels. In addition, sur-
face drainage can be controlled to decrease
infiltration, thereby reducing the potential for
mud and debris slides.
Additional engineering concerns arise in '
the case of waste management units in areas
containing karst terrain. The principal con-
cern with karst terrains is progressive or cata-
strophic subsurface failure due to the
presence of sinkholes, solution cavities, and
subterranean caverns. Extensive subsurface
characterization studies should be completed
before designing and building in these areas.
Subsurface drilling, sinkhole monitoring, and
geophysical testing are direct means that can
be used to characterize a site. Geophysical
techniques include electromagnetic conduc-
tivity, seismic refraction, ground-penetrating
radar, and electrical resistivity (see the box
below for more information). More than one
technique should be used to confirm and cor-
relate findings and anomalies, and a qualified
geophysicist should interpret the results of
these investigations.
Remote sensing techniques, such as aerial
photograph interpretation, can also provide
additional information on karst terrains.
Surface mapping can help provide an under-
standing of structural patterns and relation-
ships in karst terrains. An understanding of
local carbonate geology and stratigraphy can
help with the interpretation of both remote
sensing and geophysical data.
You should incorporate adequate engineer-
ing controls into any waste management unit ,
located in a karst terrain. In areas where karst
development is minor, loose soils overlying
the limestone can be excavated or heavily
compacted to achieve the needed stability.
Similarly,, in areas where the karst voids are
relatively small, the voids can be filled with
slurry cement grout or other material.
Engineering solutions can compensate for
dke weak geologic structures by providing
ground supports. For example, ground modi-
fications, such as grouting or reinforced raft
foundations, could compensate for a lack of
ground strength in some karst areas. Raft
constructions, which are floating foundations
consisting of a concrete footing extending
over a very large area, reduce and evenly dis-
tribute waste loads where soils have a low
bearing capacity or where soil conditions are
variable and erratic. Note, however, that raft
foundations might not always prevent the
4-17
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Getting Started—Considering the Site
Geophysical Techniques
Electromagnetic Conductivity or
Electromagnetic Induction (EMI). A transmitter
coil generates an electromagnetic field which
induces eddy currents in the earth located below
the transmitter. These eddy currents create sec-
ondary electromagnetic fields which are measured
by a receiver coil. The receiver coil produces an out-
put voltage that can be related to subsurface con- ;
ductivity variations. Analysis of these variations
allows users to map subsurface features, stratigraph-
ic profiles, and the existence of buried objects.
Seismic Refraction. An artificial seismic source
(e.g., hammer, explosives) creates compression
waves that are refracted as they travel along geologic
boundaries. These refracted waves are detected by
electromechanical transducers (geophones) which
are attached to a seismograph that records the time
of arrival of all waves (refracted and non-refracted).
These travel times are compared and analyzed to
identify the number of stratigraphic layers and the
depth of each layer.
Ground-Penetrating Radar. A transmitting
antenna dragged along the surface of the ground
radiates short pulses of high-frequency radio
waves into the ground. Subsurface structures > „
reflect these waves which are recorded by a
receiving antenna. The variations in reflected
return signals are used to generate an image or
map of the subsurface structure.
Electrical Resistivity. An electrical current is » i>,
injected into the ground by a pair of surface elec- /,
trodes (called the current electrodes). By measuring
die resulting voltage (potential field) between a sec-
ond pair of electrodes (called the potential elec-
trodes), die resistivity of subsurface materials is
measured. The measured resistivity is then com- >
pared to known values for different soil and rock
types. Increasing the distance between the two pairs
of electrodes increases die depth of measurement.
extreme collapse and settlement that can
occur in karst areas. In addition, due to the
unpredictable and catastrophic nature of
ground failure in unstable areas, the con-
struction of raft foundations and other
ground modifications tends to be complex
and can be costly, depending on the size of
the area.
F. Airport Vicinities
The vicinity of an airport includes not only
the facility itself, but also large reserved open
areas beyond the ends of runways. If a unit is
.intended to be, sited near an airport, there are
particular issues that take on added impor-
tance in such areas. You should familiarize
yourself with Federal Aviation Administration
(FAA) regulations and guidelines. The prima-
ry concern associated with waste management
units near airports is the hazard posed to air-
craft by birds, which often feed at units man-
aging putrescible waste. Planes can lose
propulsion when birds are sucked into jet
engines, and can sustain other damage in col-
lisions with birds. Industrial waste manage-
ment units that do not receive putrescible
wastes should not have a problem with birds.
Another area of concern for landfills and
waste piles near airports is the height of the
accumulated waste. If you own or. operate
such a unit, you should exercise caution
when managing waste above ground level.
How is it determined if a
prospective site will be located
too close to an airport?
If the prospective site is not located near
any airports, additional evaluation is not nec-
essary. If there is uncertainty whether the
prospective site is located near an airport,
obtain local maps of the area using the various
Internet resources previously discussed or
from state and local regulatory agencies to
identify any nearby public-use airports.
4-18
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Getting Started—Considering the Site
Topographic maps available from USGS are
also suitable for determining airport locations.
If necessary, FAA can provide information on
the location of all public-use airports. In accor-
dance with FAA guidance, if a new unit or an
expansion of an existing unit will be within 5
miles of the end of a public-use airport run-
way, the affected airport and the regional FAA
office should be notified to provide them an
opportunity for review and comment.
What can be done if a
prospective site is in an
airport vicinity?
If a proposed waste management unit or a
lateral expansion is to be located within
10,000 feet of an airport used by jet aircraft
or within 5,000 feet of an airport used only
by piston-type aircraft, design and operate
your unit so it does not pose a bird hazard to
aircraft. For above-ground units, design and
operate yotir unit so it does not interfere
with flight patterns. If it appears that height
is a potential concern, consider entrenching
the unit or choosing a site outside the air-
ports flight patterns. Most nonhazardous
industrial waste management units do not
usually manage wastes that are attractive
food sources for.birds, but if your unit han-
dles waste that potentially attracts birds, take
precautions to prevent birds from, becoming
an aircraft hazard. Discourage congregation
of birds near your unit by preventing water
from collecting on site; eliminating, or cover-
ing wastes that might serve as s: source of
food; using visual deterrents, including real-
istic models of the expected scavenger birds'
natural predators; employing sound deter-
rents, such as cannon sounds, distress calls
of scavenger birds, or the sounds of the
birds' natural predators; removing nesting
and roosting areas (unless such removal is
prohibited by the Endangered Species Act);
or constructing physical barriers, such as a
canopy of fine wires or nets strung around
the disposal and storage areas when practical
or technically feasible.
G. Wellhead Protection
Areas
Wellhead protection involves protecting
the ground-water resources that supply pub-
lic drinking water systems. A wellhead pro-
tection area (WHPA) is the area most
susceptible to contamination surrounding a
wellhead. WHPAs are designated and often
regulated to prevent public drinking water
sources from becoming contaminated. The
technical definition, delineation, and regula-
tion of WHPAs vary from state to state. You
should contact your state or local regulatory
agency to determine what wellhead protec-
tion measures are in place near prospective
sites. Section II of this chapter provides
examples of how some states specify mini-
mum allowable distances between waste
management units and public water supplies,
as well as drinking water wells. Locating a
waste management unit in a WHPA can cre-
ate 2 potential avenue for drinking water con-
tamination through accidental release of
leachate, contaminated runoff, or waste. In
addition, some states might have additional
restrictions for areas in designated "sole
source aquifier" systems.
How is it determined if a
prospective site is in a wellhead
protection area?
A list of state wellhead protection program
contacts is available on EPA's Web site at
. Also, USGS, NRCS, local
water authorities, and universities can pro-
vide maps and further expertise that can help
you to identify WHPAs. If there is uncertainty
regarding the proximity of the prospective
site to a WHPA, contact the appropriate state
or local regulatory agency.
4-19
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Getting Started—Considering the Site
What can be done if a
prospective site is in a wellhead
protection area?
If a new waste management unit or lateral
expansion will be located in a WHPA or sus-
pected WHPA, consider design modifications
to help prevent any ground-water, contami-
nation. For waste management units placed
in these areas, work with state regulatory
agencies to ensure that appropriate ground-
water barriers are installed between the unit
and the ground-water table. These barriers
should be designed using materials of
extremely low permeability, such as
geomembrane liners or low permeability soil
liners. The purpose of such barriers is to
prevent any waste, or leachate that has per-
colated through the waste, from reaching the
ground water and possibly affecting the pub-
lic drinking water source.
In addition to ground-water barriers, the
use of leachate collection, leak detection, and
runoff control systems should also be consid-
ered. Leachate contamination is possibly the
greatest threat to a public ground-water sup-
ply posed by a waste management unit.
Incorporation of leachate collection, leak
detection, and runoff control systems should
furdier prevent any leachate from escaping
into the ground water. Further discussion
concerning liner systems, leachate collection
and removal systems, and leak detection sys-
tems is included in Chapter 7, Section
B-Designing and Installing Liners.
Control systems that separate storm-water
run-on from any water that has contacted
waste should also be considered. Proper con-
trol measures that redirect storm water to the
supply source area should help alleviate this
tendency. For additional information con-
cerning storm water run-on and runoff con-
trol systems, refer to Chapter 6-Protecting
Surface Water.
If. Buffer Zone
Considerations
Many states require buffer zones between
waste management units and other nearby
land uses, such as schools. The size of a
buffer zone often depends on the type of
waste management unit and the land use of
the surrounding areas. You should consult
with state regulatory agencies and local advi-
sory boards about buffer zone requirements
before constructing a new unit or expanding
an existing unit. A summary of state buffer
zone requirements is included in the appen-
dix at the end of this chapter.
Buffer zones provide you with time and
space to mitigate situations where accidental
releases might cause adverse human health or
environmental impacts. The size of the buffer
zone will be directly related to the intended
benefit. These zones provide four primary
benefits:
• Maintenance of quality of the sur-
rounding ground water.
• Prevention of contaminant migration
off site.
• Protection of drinking water sup-
plies.
• Minimization of nuisance conditions
perceived in surrounding areas.
Protection of ground water will likely be
the primary concern for all involved parties.
You should ensure that materials processed
and disposed at your unit are isolated from
ground-water resources. Placing your unit
further from the water table and potential
receptors, and increasing the number of
physical barriers between your unit and the
water table and potential receptors, provides
for ground-water protection. It is therefore
advised that, in addition to incorporating a
liner system, where necessary, into a waste
4-20
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Getting Started—Considering the Site
Many nearby areas and land uses, such as
schools, call for consideration of buffer zones,
management unit's design, you select a site
where an adequate distance separates the bot-
tom, of a unit from the ground-water table.
(See the appendix for a summary of these
minimum separation distances.)16 In the event
of a release, this separation distance will
allow for corrective action and natural attenu-
ation to protect ground water.17
Additionally, in the event of an unplanned
release, an adequate buffer zone will, allow
time for remediation activities to control con-
taminants before they reach sensitive areas.
Buffer zones also provide additional protec-
tion for drinking water supplies. Drinking
water supplies include ground water, individ-
ual and community wells, lakes, reservoirs,
and municipal water treatment facilities.
Finally, buffer zones help maintain good
relations with the surrounding community by
protecting surrounding areas from any noise,
particulate emissions, and odor associated
with your unit. Buffer zones also help to pre-
vent access by unauthorized people. For units
located near property boundaries, houses, or
historic areas, trees or earthen berms can pro-
vide a buffer to reduce noise and odors.
Planting trees around a unit can also improve
the aesthetics of a unit, obstruct ,any view of
unsightly waste, and help protect property
values in the surrounding community. When
planting trees as a buffer, place them so that
their roots will not damage the unit's liner or
final cover.
A. Recommended Buffer
Zones
You should check with state and local offi-
cials to determine what buffer zones might
apply to your waste management unit. Areas
for which buffer zones are recommended
include property boundaries, drinking water
welfe, other sources of water, and adjacent
houses or buildings.
Property boundaries. To minimize
adverse effects on adjacent properties, consid-
er incorporating a buffer zone or separation
distance into unit design. You should consid-
er planting trees or bushes to provide a nat-
ural buffer between your unit and adjacent
properties.
Drinking water wells, surface-water
bodies, and public water supplies. Locating
a unit near or within the recharge area for
sole source aquifers and major aquifers,
coastal areas, surface-water bodies, or public
water supplies, such as a community well or
water treatment facility, also raises concerns.
Releases from a waste management unit can
pose serious threats to human health not only
where water is used for drinking, but also
where surface waters are used for recreation.
16 A detailed discussion of technical considerations concerning the design and installation of liner sys-
tems, both in situ soil liners and synthetic liners, is included in Chapter 7, Section B — Designing and
Installing Liners. . .
17 Natural attenuation can be defined as chemical and biological processes that reduce contaminant con-
centrations.
4-21
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Getting Started—Considering the Site
Houses or buildings. Waste management
units can present noise, odor, and dust prob-
lems for residents or businesses located on
adjacent property, thereby diminishing prop-
erty values. Additionally, proximity to proper-
ty boundaries can invite increased
trespassing, vandalism, and scavenging.
B. Additional Buffer Zones
There are several other areas for which to
consider establishing buffer zones, including
critical habitats, park lands, publicjoads, and
historic or archaeological sites.
Critical habitats. These are geographical
areas occupied by endangered or threatened
species. These areas contain physical or bio-
logical features essential to the proliferation of
the species. When designing a unit near a
critical habitat, it is imperative that the criti-
cal habitat be conserved. A buffer zone can
help prevent the destruction or adverse modi-
fication of a critical habitat and minimize
harm to endangered or threatened species.18
Park lands. A buffer between your unit
and park boundaries helps maintain the aes-
thetics of the park land. Park lands provide
recreational opportunities and a natural
refuge for wildlife. Locating a unit too close
to these areas can disrupt- recreational quali-
ties and natural wildlife patterns.
Public roads. A buffer zone will help
reduce unauthorized access to the unit,
reduce potential odor concerns, and improve
aesthetics for travelers, on the nearby road.
Historic or archaeological sites. A waste
management unit located in close proximity
to one of these sites can adversely impact the
aesthetic quality of the site. These areas
include historic settlements, battlegrounds,
cemeteries, and Indian burial grounds. Also
check whether a prospective site itself has
historical or archaeological significance.
Buffer zones can help protect endangered
species and their habitats.
Historic sites call for careful consideration
of buffer zones.
In summary, it is important to check with
local authorities to ensure that placement of
a new waste management unit or lateral
expansion of an existing unit will not conflict
with any local buffer zone criteria. You
should also review any relevant state or tribal
19 For the full text of the Endangered Species Act, visit the U.S. House of Representatives Internet Law
Library Web site at , under Title 16, Chapter 35.
4-22
-------
Getting Started—^Considering the Site
regulations that specify buffer zones for your
unit. For units located near any sensitive
areas as described in this section, consider
measures to minimize any possible health,
environmental, and nuisance impacts.
Ill, Local Land Use
and Zoning
Considerations
In addition to location and buffer zone
considerations, become familiar with any
local land use and zoning requirements. Local
governments often classify the land within
their communities into areas, districts, or
zones. These zones can represent different
use categories, such as residential, commer-
cial, industrial, or agricultural. You should
consider the compatibility of a planned new
unit or a planned lateral expansion with near-
by existing and future land use, and contact
local authorities early in the siting process.
Local planning, zoning, or public works offi-
cials can discuss with you the development of
a unit,, compliance with. local regulations, and
available options. Local authorities might
impose conditions for protecting adjacent
properties from potential adverse impacts
from the unit.
Addressing local land use and zoning
issues1 during the siting process can prevent
these issues from becoming prominent con-
cerns later. Land use and zoning restrictions
often address impacts on community and
recreational areas, historical areas, and other
critical areas. You should consider the prox-
imity of a new unit or lateral expansion to
suck areas and evaluate any potential adverse
effects it might have on these areas. For
example, noise, dust, fumes, and odors from
construction and operation of a unit could be
considered a nuisance and legal action could
be brought by local authorities or nearby
property owners.
In situations where land use and zoning
restrictions might cause difficulties in expand-
ing or siting a unit, work closely with local
authorities to learn about local land use and
zoning restrictions and minimize potential
problems. Misinterpreting or ignoring such
restrictions can cause complications with
intended development schedules or designs.
In many cases, the use of vegetation, fences,
or walls to screen your activities can reduce
impacts on nearby properties. In addition, it
might be possible to request amendments,
rezonings, special exceptions, or variances to
restrictions. These administrative mechanisms
allow for flexibility in use and development of
land. Learning about local requirements as
early as possible in the process will maximize
the time available to apply for variances or
rezoning permits, or to incorporate screening
into the plans for your unit.
Environmental
Justice
Considerations
In the past several years, there has been
growing recognition from communities and
federal and state governments that some
socioeconomic and racial groups might bear a
disproportionate burden of adverse environ-
mental effects from waste management activi-
ties. President Clinton issued Executive Order
12898, Federal Actions to Address
Environmental Justice in Minority
Populations and Low-Income Populations, on
February 11, 1994.19 To be consistent with
the definition of environmental justice in this
executive order, you should identify and
address, as appropriate, disproportionately
high and adverse human health or environ-
mental effects of waste management pro-
" For the full text of Presidential Executive Order No. 12898 and additional information concerning
environmental justice issues go to EPA's Web site at .
4-23
-------
Getting Started—Considering the Site
grams, policies, and activities on minority
and low-income populations.
One of the criticisms made by advocates of
environmental justice is that local communi-
ties endure the potential health and safety
risks associated with waste management
units without enjoying any of the economic
benefits. During unit siting or expansion,
address environmental justice concerns in a
manner that is most appropriate for the oper-
ations, the community, and the state or tribal
government.
You should look for opportunities to mini-
mize environmental impacts, improve the
surrounding environment, and pursue
opportunities to make the waste management
facility an asset to the community. When
planning these opportunities, it is beneficial
to maintain a relationship with all involved
parties based on honesty and integrity, utilize
cross-cultural formats and exchanges, and
recognize industry, state, and local knowl-
edge of the issues. It is also important to take
advantage of all potential opportunities for
developing partnerships.
Examples of activities that incorporate
environmental justice issues include tailoring
activities to specific needs; providing inter-
preters, if appropriate; providing multilingual
materials; and promoting the formation of a
community/state advisory panel.
Tailor the public involvement activities
to the specific needs. Good public involve-
ment programs are site-specific—they take
into account the needs of the facility, neigh-
borhood, and state. There is no such thing
as a "one-size-fits-all" public involvement
program. Listening to each other carefully
will identify the specific environmental jus-
tice concerns and determine the involve-
ment activities most appropriate to address
those needs.
Provide interpreters for public meetings.
Interpreters can be used to ensure the infor-
mation is exchanged. Provide interpreters, as
needed, for the hearing impaired and for any
languages, other than English, spoken by a
significant percentage of the audience.
Provide multilingual fact sheets and
other information. Public notices and fact
sheets should be distributed in as many lan-
guages as necessary to ensure that all inter-
ested parties receive necessary information.
Fact sheets should be available for the visual-
ly impaired in the community on tape, in
large print, or braille.
Promote the formation of a community/
state advisory panel to serve as the voice of
the community. The Louisiana Department
of Environmental Quality, for example,
encourages the creation of environmental jus-
tice panels comprised of community mem-
bers, industry, and state representatives. The
panels meet monthly to discuss environmen-
tal justice issues and find solutions to any
concerns identified by the group.
4-24
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Getting Started—Considering the Site
Considering the Site Activity List
General Siting Considerations
D Check to see if the proposed unit site is:
— In a 100-year floodplain.
— . In or near a wetland area.
— Within 200 feet of an active fault.
— In a seismic impact zone.
— In an unstable area.
— Close to an airport.
— Within a wellhead protection area.
D If the proposed unit site is in any of these areas:
— Design the unit to account for the area's characteristics and minimize the unit's impacts on
such areas.
— Consider siting the unit elsewhere.
Buffer Zone Considerations
(Note that many states require buffer zones between waste management units and other nearby land
uses.)
D Check to see if the proposed unit site is near:
— The ground-water table.
A property boundary
— A drinking water well.
— A public water supply, such as a community well, reservoir, or water treatment facility
— A surface-water body, such as a lake, stream, river, or pond.
— Houses or other buildings.
— Critical habitats for endangered or threatened species.
— Park lands.
— A public road.
— Historic or archaeological sites.
Q If the proposed unit site is near any of these areas or land uses, determine how large a buffer zone,
if any, is appropriate between the unit and the area or land use.
4-25
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Getting Started—Considering the Site
Considering the Site Activity List (cont.)
Local Land Use and Zoning Considerations
D Contact local planning, zoning, and public works agencies to discuss restrictions that apply to the
unit.
D Comply wida any applicable restrictions, or obtain the necessary variances or special exceptions.
Environmental Justice Considerations
D Determine whedier minority or low-income populations would bear a disproportionate burden of
any environmental effects of the unit's waste management activities.
O Work with the local community to devise strategies to minimize any potentially disproportionate
burdens.
-------
Getting Started—Considering (he Site
Resources
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills. John Wiley & Sons Inc.
Das, B. M. 1990. Principles of Geotechnical Engineering. 2nd ed. Boston: PWS-Kent Publishing Co.
Federal Emergency Management Agency. How to Read a Flood Insurance Map. Web Site:
Federal Emergency Management Agency. The National Flood Insurance Program Community Status Book.
Web Site:
Federal Emergency Management Agency. 1995. The Zone A Manual: Managing Floodplain Development in
Approximate Zone A Areas. FEMA 265.
Illinois Department of Energy and Natural Resources. 1990. Municipal Solid Waste Management Options:
Volume II:. Landfills.
Law, J., C. Leung, P. Mandeville, and A. H. Wu. 1996. A Case Study of Determining Liquefaction Potential of
a New Landfill Site in Virginia by Using Computer Modeling. Presented at WasteTech '95, New Orleans, LA
Qanuary).
Noble, George., 1992. Siting Landfills and Other LULUs. Technomic Publications.
Oregon Department of Environmental Quality. 1996. Wellhead Protection Facts. Web Site:
.
Terrene Institute. 1996. American Wetlands: A Reason to Celebrate.
Texas Natural Resource Conservation Commission. 1983. Industrial Solid Waste Landfill Site Selection.
U.S. Army Corps of Engineers. 1995. Engineering and Design: Design and Construction of Conventionally
Reinforced Ribbed Mat Slabs (RRMS). ETL 1110-3-471.
U.S. Army Corps of Engineers., 1995. Engineering and Design: Geomembranes for Waste Containment
Applications. ETL 1110-1-172.
U.S. Army Corps of Engineers. 1992. Engineering and Design: Bearing Capacity of Soils. EM 1110-1-1905.
U.S. Army Corps of Engineers. 1992. Engineering and Design: Design and Construction of Grouted Riprap
ETL 1110-2-334.
4-27
-------
Getting Started—Considering the Site
Resources (cont.)
U.S. Army Corps of Engineers. 1991. 1987 U.S. Army Corps of Engineers Wetlands Delineation Manual.
HQUSACE.
U.S. Army Corps of Engineers. 1984. Engineering and Design: Use of Geotextiles Under Riprap. ETL
1110-2-286.
U.S. EPA. 2000a. Social Aspects of Siting RCRA Hazardous Waste Facilities. EPA530-K-00-005.
U.S. EPA. 2000b. Siting of Hazardous Waste Management Facilities and Public Opposition. EPAOSW-0-00-809.
U.S. EPA. 1997. Sensitive Environments and the Siting of Hazardous Waste Management Facilities.
EPA530-K-97-003.
U.S. EPA. 1995a. OSWER Environmental Justice Action Agenda. EPA540-R-95-023.
U.S. EPA. 1995b. Decision-Maker's Guide to Solid Waste Management, 2nd Ed. EPA530-R-95-023.
U.S. EPA. 1995c. RCRA Subtitle D (258) Seismic Design Guidance for Municipal Solid Waste Landfill
Facilities. EPA600-R-95-051.
U.S. EPA. 1995d. Why Do Wellhead Protection? Issues and Answers in Protecting Public Drinking Water
Supply Systems. EPA813-K-95-001.
U. S. EPA. 1994. Handbook: Ground Water and Wellhead Protection. EPA625-R-94-001.
U. S. EPA. 1993a. Guidelines for Delineation of Wellhead Protection Areas. EPA440-5-93-001.
U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U. S. EPA. 1992. Final Comprehensive State Ground-Water Protection Program Guidance. EPA100-R-93r001.
U. S. EPA. 1991. Protecting Local Ground-Water Supplies Through Wellhead Protection. EPA570-09-91-007.
U. S. EPA. 1988. Developing a State Wellhead Protection Program: A User's Guide to Assist State Agencies
Under the Safe Drinking Water Act. EPA440-6-88-003.
U.S. Geological Survey. Preliminary Young Fault Maps, Miscellaneous Field Investigation 916.
4-28
-------
Getting Started—Considering the Site
Resources (cont.)
U.S. Geological Survey. Probabilistic Acceleration and Velocity Maps for the United States and Puerto Rico.
Map Series MF-2120. ,.
U.S. House of Representatives. 1996. Endangered Species Act, Internet Law Library. Web Site:
.
University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1990.
Municipal solid waste landfills: Volume II: Technical issues.
University of Illinois Center for Solid Waste Management and Research, Office of Technology Transfer. 1989.
Municipal Solid Waste Landfills: Vol. I: General Issues.
White House. Executive Order 12898 Federal Actions to Address Environmental Justice in Minority
Populations and Low-Income Populations.
4-29
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Getting Started—Considering the Site
Appendix: State Buffer Zone Considerations
The universe of industrial wastes and unit types is broad and diverse. States have established
various approaches to address location considerations for the variety of wastes and units in
their states. The tables below summarize the range of buffer zone restrictions and most com-
mon buffer zone values specified for each unit type by some states to address their local con-
cerns. The numbers in the tables are not meant to advocate the adoption of a buffer zone of
any particular distance; rather, they serve only as examples of restrictions states have individu-
ally developed.
• Surface impoundments. Restrictions with respect to buffer zones vary among states.
In addition, states allow exemptions or variances to these buffer zone restrictions on a
case-by-case basis. Table 1 presents the range of values and the most common value
used by states for each buffer zone category.
Table 1
State Buffer Zone Restrictions for Surface Impoundments
Buffer Zone Category Range of Values — minimum Most Common Value (number of
; distance (number of states i states with this1 common value)
with this common value) ' ; I
Groundwater Table
Property Boundaries
Drinking Water Wells
Public Water Supply-
Surface Water Body
Houses or Buildings
Roads
1 to 15 feet
100 to 200 feet
1,200 to 1,320 feet
500 to 1,320 feet
100 to 1,320 feet
300 to 1,320 feet
1,000 feet
(4)
(4)
(2)
(4)
(4)
(4)
(1)
5 feet
100 feet
1,200 feet
1,320 feet
1,320 feet
100 feet
1,320 feet
1,000 feet
(2)
(2)
(1)
(1)
(2)
(2)
(2)
(1)
4-30
-------
Getting Started—Considering the Site.
Landfills. Table 2 presents the range of values and the most common state buffer zone
restrictions for landfills.
Table 2
State Buffer Zone Restrictions for Landfills
ifeuffer Zone Category Range of Values— minimum ; Most CommonValue (number of
distance (number ot states with states with this common value)
;,,- this common value) ' ;
Groundwater Table
Property Boundaries
Drinking Water Wells
Public Water Supply
Surface Water Body
Houses or Buildings
Roads
Park Land
Fault Areas
1 to 15 feet
20 to 600 feet
500 to 1,320 feet
400 to 5,280 feet
100 to 2,000 feet
200 to 1,320 feet
50 to 1,000 feet
1,000 to 5,280 feet
200 feet
(12)
(14)
(9)
(13)
(20)
(14)
(8)
(7)
(2)
5 feet
100 feet
500 feet
600 feet
1,200 feet
1,200 feet
100 feet
1,000 feet
500 feet
1,000 feet
1,000 feet
200 feet
(4)
(7)
. (2)
(2)
(2)
(3)
(5)
(5)
(7)
(5)
(4)
(2)
4-31
-------
Getting Started—Considering the Site
Waste Piles. Table 3 presents the state buffer zone restrictions for waste piles. Of the
four states with buffer zone restrictions, only two states specified minimum distances.
Table 3
State Buffer Zone Restrictions for Waste. Piles
Buffer Zone Category - Range of Values-minimum v Most Common Value) (number of
: distance (number of states states with this common value) i
with this common value) , _-'••. . •'; •
^^^^^^^^^^^^^^^^^^^^^™^™^™
Groundwater Table
Property Boundaries
Surface Water Body
Houses or Buildings or
Recreational Area
Historic Archeological Site
or Critical Habitat
MH^MMHMi^^^^^^^H^^^^^HB
4 feet*
50 feet
50 feet
200 feet
Minimum distance
not specified
(1)
(1)
(1)
(1)
(1)
4 feet*
50 feet
50 feet
200 feet
Minimum distance
not specified
(1)
(1)
(1)
(1)
(1)
* If no liner or storage pad is used, then this state requires four feet between the waste and
the seasonal high water table.
4-32
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Getting Started—Considering the Site
Land Application.20 Table 4 presents the range of values and the most common state
buffer zone restrictions for land application.
Table 4
State Buffer Zone Restrictions for Land Application
; Buffer Zone Category Range of Values-minimum Most Common Value (number of
. ' , distance (number of states with ; states with this common value)
, ,, this common value)
Groundwater Table
Property Boundaries
Drinking Water Wells
Public Water Supply
Surface Water Body
Houses or Buildings
Park Land
Fault Areas
Max. Depth of Treatment
Pipelines
Critical Habitat
Soil Conditions
4 to 5 feet
50 to 200 feet
200 to 500 feet
300 to 5,280 feet
100 to 1,000 feet
200 to 3,000 feet
2,640 feet
200 feet
5 feet
25 feet
No minimum distance set
(3)
(4)
(2)
(3)
(5)
(6)
CD
(1)
(1)
(1)
(2)
Not on frozen, ice or snow (1)
covered, or water saturated soils
4 feet
5 feet
50 feet
200 feet
500 feet
300 feet
1,000 feet
5,280 feet
100 feet
300 feet
500 feet
2,640 feet
200 feet
5 feet
25 feet
No minimum distance set
(1)
(1)
(2)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
(2)
CD
(1)
(1)
(1)
(2)
Not on frozen, ice or snow (1)
covered, or water saturated soils
20 In the review of state regulations performed to develop Table 5, it was not possible to distinguish
between units used for treatment and units where wastes are added as a soil amendment. It is recom-
mended that you consult applicable state agencies to determine which buffer zone restrictions are rele-
vant to your land application unit.
4-33
-------
Gelling Started—Considering the Site
Based on the review of state requirements, Table 5 presents the most common buffer zones
restrictions across all four unit types.
Table 5
Common Buffer Zone Restrictions Across All Four Unit Types
Buffer Zone Category ; Most Common Values : 1 '.]'• ;
(total number of states for all unit types) ! (number of states with this icommon value1)
Groundwater Table
Property Boundaries
Drinking Water Wells
Public Water Supply
Surface Water Body
Houses or Buildings
(20)
(23)
(13)
(20)
(30)
(25)
4 feet
5 feet
50 feet
100 feet
500 feet
1,000 feet
1,200 feet
5,280 feet
100 feet
200 feet
1,000 feet
500 feet
(4)
(4)
(8)
(5)
(3)
(3)
(3)
(3)
(5)
(5)
(7)
(9)
4-34
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Part II
Protecting Air Quality
Chapter 5
Protecting Air Quality
-------
-------
Contents
I. Federal Airborne Emission Control Programs , 5.3
A. National Ambient Air Quality Standards 5.3
B. New Source Performance Standards 5.3
C. National Emission Standards for Hazardous Air Pollutants 5-4
D. Title V Operating Permits 5_10
E. Federal Airborne Emission Regulations for Solid Waste Management Activities 5-10
1. Hazardous Waste Management Unit Airborne Emission Regulations 5-10
. 2. Municipal Solid Waste Landfill Airborne Emission Regulations 5-10
3. Offsite Waste and Recovery Operations NESHAP 5-11
E A Decision Guide to Applicable CAA Requirements 5-12
1. Determine Emissions from the Unit 5_12
2. Is the Waste Management Unit Part of an Industrial Facility Which Is Subject to a CAA
Title V Opening Permit? 5-14
3. Conduct a Risk Evaluation Using One of the Following Options: 5-17
II. Assessing Risk 5-17
A. Assessing Risks Associated with Inhalation of Ambient Air 5-17
B. IWAIR Model : 5_21
1. Emissions Model ', 5-21
2. Dispersion Model 5_2l
3. Risk Model 5-23
4. Estimation Process 5-23
5. Capabilities and Limitations of the Model ; 5-27
C. Site-specific Risk Analysis .' 5-28
III. Emission Control Techniques 5-32
A. Controlling Particulate Matter 5_32
1. Vehicular Operations 5-32
2. Waste Placement and Handling 5.33
3. Wind Erosion 5-35
B. VOC Emission Control Techniques 5_36
1. Choosing a Site to Minimize Airborne Emission Problems 5-36
2. Pretreatment of Waste ...5-36
3. Enclosure of Units 5-36
4. Treatment of Captured VOCs 5-37
5. Special Considerations for Land Application Units 5-38
Protecting Air Activity List 5.39
-------
Contents
Resources 5-40
Figures:
Figure 1. Evaluating VOC Emission Risk 5-13
Figure 2. Conceptual Site Diagram ..: •• 5-18
Figure 3. Emissions from WMU . 5-19
Figure 4. Forces That Affect Contaminant Plumes 5-20
Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations 5-24
Figure 6. Screen 1, Method, Met Station, WMU ....5-25
Figure 7. Screen 2, Wastes Managed 5-25
Tables:
Table 1. Industries for Which NSPSs Have Been Established - 5-5
Table 2. HAPs Defined in Section 112 of the CAA Amendments of 1990 5-6
Table 3. Source Categories With MACT Standards 5-8
Table 4, Major Source Determination in Nonattainment Areas 5-15
Table 5. Constituents Included in IWAIR 5-22
Table 6. Source Characterization Models ; 5-29
Table 7. Example List of Chemical Suppressants 5-34
-------
Protecting Air Quality—Protecting Air Quality
Protecting Air Quality
This chapter will help you address:
• Airborne particulates and air emissions that can cause human health
risks and damage the environment by adopting controls to minimize
particulate emissions.
• Assessing risks associated with air emissions and implementing pol-
lution prevention, treatment, or controls as needed to reduce risks
for a facility's waste management units not addressed by require-
ments under the Clean Air Act.
• Using a Clean Air Act Title V permit, at facilities that must obtain
one, as a vehicle for addressing air emissions from certain waste
management units.
Health effects from airborne pol-
lutants can be minor and
reversible (such as eye irrita-
tion), debilitating (such as
asthma), or chronic and poten-
tially fatal (such as cancer). Potential health
impacts depend on many factors, including
the quantity of air pollution to which people
are exposed, the duration of exposures, and
the toxicity associated with specific pollu-
tants. An air risk assessment takes these fac-
tors into account to predict the risk or
hazards posed at a particular site or facility.
This chapter will help you address the fol-
lowing questions.
• Is a particular facility subject to CAA
requirements?;
• What is an air nsk assessment?
• Do waste management units pose risks
from volatile air emissions?
• What controls will reduce particulate
and volatile emissions from a facility?
Air releases from waste management, units
include particulates or wind-blown dust and
gaseous emissions from volatile compounds
It is recommended that every facility
implement controls to address emissions of
airborne particulates. Particulates have imme-
diate and highly visible impacts on surround-
ing neighborhoods. They can affect human
health and can carry constituents off site as
well. Generally, controls are achieved through
good operating practices.
For air releases from industrial waste man-
agement units, you need to know what regula-
tory requirements under the Clean Air Act
(CAA) apply to your facility, and whether diose
requirements address waste management units.
The followup question for facilities whose
waste management units are not addressed by
CAA requirements, is "are there risks from air
releases that should be controlled?"
This Guide provides two tools to help you
answer these questions. First, this chapter
includes an overview of the major emission
control requirements under the CAA and a
decision guide to evaluate which of these
5-1
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Protecting Air Quality—Protecting Air Quality
might apply to a facility. The steps of the deci-
sion guide are summarized in Figure 1. Each
facility subject to any of these requirements
will most likely be required to obtain a CAA
Title V operating permit. The decision guide
will help you clarify some of the key facility
information you need to identify applicable
CAA requirements.
If your answers in the decision guide indi-
cate that the facility is or might be subject to
specific regulatory obligations, the next step is
to consult with EPA, state, or local air quality
program staff. Some CAA regulations are
industry-specific and operation-specific within
an industry, while others are pollutant specific
or specific to a geographic area. EPA, state, or
local air quality managers can help you pre-
cisely determine applicable requirements and
whether waste management units are
addressed by those requirements.
You might find that waste management
units are not addressed or that a specific facili-
ty clearly does not fit into any regulatory cate-
gory under the CAA. It is then prudent to
look beyond immediate permit requirements
to assess risks associated with volatile organic
compounds (VOCs) released from the unit. A
two-tiered approach to this assessment is rec-
ommended, depending on the complexity and
amount of site specific data you have.
Limited Site-Specific Air Assessment:
The CD-ROM version of the Guide contains
the Industrial Waste Air Model (IWAIR). If a
waste contains any of the 95 constituents
included in the model, you can use this risk
model to assess whether VOC emissions pose
a risk that warrants additional emission con-
trols or that could be addressed more effec-
tively with pollution prevention or waste
treatment before placement in the waste man-
agement unit. The IWAIR model allows users
to supply inputs for an emission estimate and
for a dispersion factor for the unit.
Comprehensive Risk Assessment: This
assessment relies on a comprehensive analysis
of waste and site-specific data and use of mod-
els designed to assess multi-pathway exposures
to airborne contaminants. There are a number
of modeling tools available for this analysis.
You should consult closely with your air quali-
ty management agency as you proceed.
Airborne emissions are responsible for the loss of visibility between the left and right pho-
tographs of the Grand Canyon. Source: National Park Service, Air Resources Division.
5-2
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Protecting Air Quality:—Protecting Air Qualify
I Federal Airborne
Emission Control
Programs
Four major federal programs address air-
borne emissions that can degrade air quality.
For more information about the CAA and
EPA's implementation of it, visit the
Technology Transfer Network, EPA's premier
technical Web site for information transfer
and sharing related to air pollution topics, at
.
If the facility is a major source or other-
wise subject to Title V of the CAA, the owner
must obtain a Title V operating permit. These
permits are typically issued by the state air
permitting authority. As part of the permitting
process, you will be required to develop an
emissions inventory for the facility. Some
states have additional permitting require-
ments. Whether or not emissions from a
waste management unit will be specifically
addressed through the permit process
depends on a number'of factors, including
the type of facility and state permitting
resources and priorities. It is prudent, howev-
er, where there are no applicable air permit
requirements to assess whether there rmgfit
be risks associated with waste management
units and to address these risks.
A. National Ambient Air
Quality Standards
The CAA authorizes EPA to establish emis-
sion limits to achieve National Ambient Air
Quality Standards (NAAQS).' EPA has desig-
nated NAAQS for the following criteria pollu-
tants: ozone, sulfur dioxide, nitrogen dioxide,
lead, paniculate matter (PM), and carbon
monoxide. The NAAQS establish individual
pollutant concentration ceilings that should
be rarely exceeded in a predetermined geo-
graphical area (National Ambient Air Quality
District). NAAQS are not .enforced directly by
EPA. Instead, each state must submit a State
Implementation Plan (SIP) describing how it
will achieve or maintain NAAQS. Many SIPs
call for airborne emission limits on industrial
facilities.
If a waste emits VOCs, some of which are
precursors to ozone, the waste management
unit could be affected by EPA's NAAQS for
ground-level ozone. Currently, states are
implementing an ozone standard of 0.12
parts per million (ppm) as measured over a
1-hour period. In 1997, EPA promulgated a
revised standard of 0.08 ppm with an 8-hour
averaging time to protect public health and
the environment over longer exposure peri-
ods2 (see 62 FR 38856, July 18, 1997). EPA is
currently developing regulations and guid-
ance for implementing the 8-hour ozone
standard. EPA expects to designate areas as
attaining or not attaining the standard in
2004. At that time, areas not attaining the
standard will need to develop plans to control
emissions and to demonstrate how they will
reach attainment. Consult with your state to
deteimine whether efforts to comply with the
ozone NAAQS involve VOC emission limits
that apply to a specific facility. General ques-
tions about the 8-hour standard should be
directed to EPA's Office of Air Quality
Planning and Standards, Air Quality
Strategies and Standards Division, Ozone
Policy and Strategies Group, MD-15,
Research Triangle Park, NC 27711, telephone
919 541-5244.
B. New Source
Performance Standards
New Source Performance Standards
(NSPSs) are issued for categories of sources
that cause or contribute significant air pollu-
42 U.S.C. § 7409
For a discussion of the history of the litigation over the revised ozone standard a«J EPA's pkn for
implementing it, including possible revisions to 40 CFR 50.9(b), see 67 FR 48896 (July 26, 2002).
5-3
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Protecting Air Quality—Protecting Air Quality
tion that can reasonably be anticipated to
endanger public health or welfare. For indus-
try categories, NSPSs establish national tech-
nology-based emission limits for air pollutants,
such as paniculate matter (PM) or VOCs.
States have primary responsibility for assuring
that the NSPSs are followed. These standards
are distinct from NAAQS because they estab-
lish direct national emission limits for speci-
fied sources, while NAAQS establish air
quality targets that states meet using a variety
of measures that include emission limits. Table
1 lists industries for which NSPSs have been
established and locations of the NSPSs in the
Code of Federal Regulations. You should
check to see if any of the 74 New Source
Performance Standards (NSPSs)3 apply to the
facility.4 Any facility subject to a NSPS must
obtain a Title V permit (see Section D below.).
C. National Emission
Standards for Hazardous
Air Pollutants
Section 112 of the CAA Amendments of
1990' requires EPA to establish national stan-
dards to reduce emissions from a set of certain
pollutants called hazardous air pollutants
(HAPs). Section 112(b) contains a list of 188
HAPs (see Table 2) to be regulated by National
Emission Standards for Hazardous Air
Pollutants (NESHAPs) referred to as Maximum
Achievable Control Technology (MACT) stan-
dards, that are generally set on an industry-by-
industry basis.
MACT standards typically apply to major
sources in specified industries; however, in
some instances, non-major sources also can be
subject to MACT standards. A major source is
defined as any stationary source or group of
stationary sources that (1) is located within a
contiguous area and under common control,
and (2) emits or has the potential to emit at
least 10 tons per year (tpy) of any single HAP
or at least 25 tpy of any combination of HAPs.
All fugitive emissions of HAPs, including emis-
sions from waste management units, are to.be
taken into account in determining whether a
stationary source is a major source. Each
MACT standard might limit specific opera-
tions, processes, or wastes that are covered.
Some MACT standards specifically cover waste
management units, while others do not. If a
facility is covered by a MACT standard, it
must be permitted under Title V (see below).
EPA has identified approximately 170 indus-
trial categories and subcategories that are or will
be subject to MACT standards. Table 3 lists the
categories for which standards have been final-
ized, proposed, or are expected. The CAA calls
for EPA to promulgate the standards in four
phases. EPA is currently in the fourth and final
phase of developing proposed regulations.
CAA also requires EPA to assess the risk to
public health remaining after the implementa-
tion of NESHAPs and MACT standards. EPA
must determine if more stringent standards are
necessary to protect public health with an
ample margin of safety or to prevent an
adverse environmental effect. As a first step in
this process the CAA requires EPA to submit a
Report to Congress on its methods for making
the health risks from residual emissions deter-
mination. The final report, Residual Risk
Report to Congress (U.S. EPA, 1997b), was
signed on March 3, 1999 and is available from
EPA's Web site at . If significant resid-
ual risk exists after application of a MACT,
EPA must promulgate health-based standards
for that source category to further reduce HAP
emissions. EPA must set residual risk stan-
dards within 8 years after promulgation of
each NESHAP.
5-4
1 40CFRPart60.
4 While NSPSs apply to new facilities, EPA also established emission guidelines for existing facilities.
5 42 U.S.C. § 7412.
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Protecting Air Quality—Protecting Air Quality
Table 1. Industries for Which NSPSs Have Been Established
For electronic versions of the 40 CFR Part 60 subparts referenced below, visit
. Be sure to check the Federal Register for updates that have
been published since publication of this Guide.
Ammonium Sulfate Manufacture PP
Asphalt Processing & Asphalt Roofing Manufacture UU
Auto/Id Truck Surface Coating Operations MM
Basic Oxygen Process Furnaces after 6/11/73 N
Beverage Can Surface Coating Industry WW
Bulk Gasoline Terminals XX
Calciners and Dryers in Mineral Industry UUU
Coal Preparation Plants Y
Commercial & Industrial SW Incinerator Units CCCC
Electric Utility Steam Generating Units after 9/18/78 DA
Equipment Leaks of VOC in Petroleum Refineries GGG
Equipment Leaks of VOCin SOCMI W
Ferroalloy Production Facilities Z
Flexible Vinyl & Urethane Coating & Printing FFF
Fossil-met Fired Steam Generators after 8/17/71 D
Glass Manufacturing Plants CC
Grain Elevators DD
Graphic Arts: Publication Rotogravure Printing QQ
Hot Mix Asphalt Facilities I
Incinerators • E
Industrial Surface Coating, Plastic Parts TTT
Industrial Surface Coating-Large Appliances SS
Industrial-Commerdal-Institutional Steam Generation UnitDB
Kraft Pulp Mills . BB
Large Municipal Waste Combustors after 9/20/94 EB
Lead-Acid Battery Manufacturing Plants KK
Lime Manufacturing HH
Magnetic Tape1 Coating Facilities SSS
Medical Waste Incinerators (MWI) after 6/20/96 EC
Metal Coil Surface Coating TT
Metallic Mineral Processing Plants LL
Municipal Solid Waste Landfills after 5/30/91 WWW
Municipal Waste Combustors (MWC) EA
New Residential Wood Heaters AAA
Nitric Acid Plants G
Nonmetallic Mineral Processing Plants OOO
Onshore Natural Gas Processing Plants, VOC Leaks KKK
Onshore Natural Gas Processing: SO2 Emissions LLL
Petroleum Dry Cleaners, Rated Capacity 84 Lb JJJ
Petroleum Refineries J
Petroleum Refinery Wastewater Systems QQQ
Phosphate Fertilizer-Wet Process Phosphoric Acid T
Phosphate Fertilizer-Superphosphoric Acid U
Phosphate Fertilizer-Diammonium Phosphate V
Phosphate Fertilizer-Triple Superphosphate W
Phosphate Fertilizers: GTSP Storage Facilities X
Phosphate Rock Plants NN
Polymer Manufacturing Industry DDD
Polymeric Coating of Supporting Substrates Fac. WV
Portland Cement Plants F
Pressure. Sensitive Tape & Label Surface Coating RR
Primary Aluminum Reduction Plants S
Primary Copper Smelters P
Primary Lead Smelters R
Primary Zinc Smelters Q
Rubber Tire Manufacturing Industry EBB
Secondary Brass and Bronze Production Plants M
Secondary Lead Smelters L
Sewage-Treatment Plants O
Small Indust7Comm./Institut. Steam Generating Units DC
Small' Municipal Waste Combustion Units AAAA
SOCMI - Air Oxidation Processes . Ill
SOCMI - Distillation Operations NNN
SOCMI Reactors RRR
SOCMI Wastewater YYY
Stationary Gas Turbines GG
Steel Plants: Elec. Arc Furnaces after 08/17/83 AAA
Steel Plants: Electric Arc Furnaces AA
Storage Vessels for Petroleum liquids (6773-5/78) K
Storage Vessels for Petroleum Liquids (5/78-6/84) KA
Sulfuric Acid Plants H
Surface Coating of Metal Furniture EE
Synthetic Fiber Production Facilities HHH
Volatile Storage Vessel (Incl. Petroleum) after 7/23/84 KB
Wool Fiberglass Insulation Manufacturing Plants PPP
5-5
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Protecting Air Quality—Protecting Air Quality
Table 2
HAPs Defined in Section 112 of the CAA Amendments of 1990
||' - • • ! - . - .' : •• • - ' ' . -. - ' .-•) --I •.-.-•: I •!'
£AS# , CHEMICAL NAME , CAS# CHEMICAL NAME . CAS# CHEMICAL NAME I
75-07-0 Acetaldehyde
60-35-5 Acetamide
75-05-8 Acetonitrile
98-85-2 Acetophenone
53-96-3 2-AcetyIaminofluorene
107-02-8 Acrolein
79-06-1 Acrylamidc
79-10-7 Acrylic acid
107-13-1 Acrylonitrile
107-05-1 Ally! chloride
92-67-1 4-Aminobiphenyl
62-53-3 Aniline
90-04-0 o-Anisidine
1332-21-4 Asbestos
71-43-2 Benzene (including benzene
from gasoline)
92-87-5 Benzidine
98-07-7 Benzotrichloride
100-44-7 Benzyl chloride
92-52-4 Biphenyl
117-81-7 Bis(2-ethylhexyl) phthalate
(DEHP)
542-88-1 Bis(chloromethyl)ether
75-25-2 Bromolbrm
106-99-0 1,3-Butadiene
156-62-7 Calcium cyanamide
133-06-2 Captan
63-25-2 Carbaryl
75-15-0 Carbon disulfide
56-23-5 Carbon telrachloride
463-58-1 Carbonyl sulfide
120-80-9 Catechol
133-90-4 Chloramben
57-74-9 Chlordane
7782-50-5 Chlorine
79-11-8 Chloroacetic acid
532-27-4 2-Chloroacetophenone
108-90-7 Chlorobenzene
510-15-6 Chlorobenzilate
67-66-3 Chloroform
107-30-2 Chloromethyl methyl ether
126-99-8 Chloroprene
1319-77-3 Cresols/Cresylic acid (isomers
and mixture;
95-48-7 o-Cresol
108-39-4 m-Cresol
106-44-5 p-Cresol
98-82-8 Cumene
94-75-7 2,4-D, salts and esters
72-55-9 DDE
334-88-3 Diazomethane
132-64-9 Dibenzofurans .
96-12-8 l,2-Dibromo-3-chloropropane
84-74-2 Dibutylphthalate
106-46-7 l,4-Dichlorobenzene(p)
91-94-1 3,3-Dichlorobenzidene
111-44-4 Dichloroethyl ether (Bis(2-
chloroethyl)ether)
542-75-6 1,3-Dichloropropene
62-73-7 Dichlorvos
111-42-2 Diethanolamine
121-69-7 N,N-Diethyl aniline (N,N-
Dimethylaniline)
64-67-5 Diethyl sulfate
119-90-4 3,3-Dimethoxybenzidine
60-11-7 Dimethyl aminoazobenzene
119-93-7 3,3'-Dimethyl benzidine
79-44-7 Dimethyl carbamoyl chloride
68-12-2 Dimethyl formamide
57-14-7 1,1-Dimethylhydrazine
131-11-3 Dimethyl phthalate
77-78-1 Dimethyl sulfate
534-52-1 4,6-Dinitro-o-cresol, and salts
51-28-5 2,4-Dinitrophenol
121-14-2 2,4-Dinitrotoluene
123-91-1 1,4-Dioxane (1,4-
Diethyleneoxide)
122-66-7 1,2-Diphenylhydrazine
106-89-8 Epichlorohydrin (1-Chloro- 2,3-
epoxypropane)
106-88-7 1,2-Epoxybutane
140-88-5 Ethyl acrylate
100-41-4 Ethyl benzene
51-79-6 Ethyl carbamate (Urethane)
75-00-3 Ethyl chloride (Chloroethane)
106-93-4 Ethylene dibromide
(Dibromoethane)
107-06-2 Ethylene dichloride (1,2-
Dichloroe thane)
107-21-1 Ethylene glycol
151-56-4 Ethylene imine (Aziridine)
75-21-8 Ethylene oxide
96-45-7 Ethylene thiourea
75-34-3 Ethylidene dichloride (1,1-
Dichloroe thane)
50-00-0 Formaldehyde
76-44-8 Heptachlor
118-74-1 Hexachlorobenzene
87-68-3 Hexachlorobutadiene
77-47-4 Hexachlorocyclopenta-diene
67-72-1 Hexachloroethane
822-06-0 Hexamethylene-1 ,6-diisocyanate
680-31-9 Hexamethylphosphor-amide
110-54-3 Hexane
302-01-2 Hydrazine
7647-01-0 Hydrochloric acid
7664-39-3 Hydrogen fluoride
(Hydrofluoric acid)
123-31-9 Hydroquinone
78-59-1 Isophorone
58-89-9 Lindane (all isomers)
108-31-6 Maleic anhydride
67-56-1 Methanol
72-43-5 Methoxychlor
74-83-9 Methyl bromide
(Bromomethane)
74-87-3 Methyl chloride
(Chloromethane)
71-55-6 Methyl chloroform (1,1,1-
Trichloroe thane)
78-93-3 Methyl ethyl ketone (2-
Butanone)
60-34-4 Methyl hydrazine
74-88-4 Methyl iodide (lodomethane)
108-10-1 Methyl isobutyl ketone
(Hexone)
624-83-9 Methyl isocyanate
80-62-6 Methyl methacrylate
1634-04-4 Methyl tert butyl ether
101-14-4 4,4-Methylene bis(2-chloroani-
line)
75-09-2 Methylene chloride
(Dichloromethane)
101-68-8 Methylene diphenyl diiso-
cyanate (MDI)
101779 4,4'-Methylenedianiline
91-20-3 Naphthalene
98-95-3 Nitrobenzene
92-93-3 4-Nitrobiphenyl
100-02-7 4-Nitrophenol
79-46-9 2-Nitropropane
684-93-5 N-Nitroso-N-methylurea
62-75-9 N-Nitrosodimethylamine
59-89-2 N-Nitrosomorpholine
56-38-2 Parathion
82-68-8 Pentachloronitrobenzene
(Quintobenzene)
87-86-5 Pentachlorophenol
108-95-2 Phenol
106-50-3 p-Phenylenediamine
75-44-5' Phosgene
7803-5 1-2 Phosphine
5-6
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Protecting Air Quality—Protecting Air Quality
Table 2
HAPs Defined in Section 112 of the CAA Amendments of 1990 (cont)
GAS*;RCHEMlCAt NAME
-: CAS# ,-.: CHEMICAL; NAME
,GAS#?. CHEMICAL NAME.
7723-14-0 Phosphorus
85-44-9 Phthalic anhydride
1336-36-3 Polychlorinated biphenyls
(Aroclors)
1120-71-41,3-Propane sultone
57-57-8 beta-Propiolactone
123-38-6 Propionaldehyde
114-26-1 Propoxur (Baygon)
78-87-5 Propylenedichloride(l,2-
Dichloropropane)
Propylene oxide
75-56-9
75-55-8
1,2-Propylenimine (2-Methyl
aziridine)
91-22-5 Quinoline
106-51-4 Quinone (p-Benzoquinone)
100-42-5 Styrene
96-09-3 Styrene oxide
1746-01-6 2,3,7,8-Tetrachlorodi-benzo-p-
dioxin
79-34-5 l,l;2,2-Tetrachloroethane
127-18-4 Tetrachloroethylene
(Perchloroethylene)
7550-45-0 Titanium tetrachloride
108-88-3 Toluene
95-80-7 2,4-Toluene diamine '
584-84-9 2,4-Toluene diisocyanate
95-53-4 o-Toluidine
8001-3 5-2 Toxaphene (chlorinated cam-
phene)
120-82-1 1,2,4-Trichlorobenzene
79-00-5 1,1,2-Trichloroethane
79-01-6 Trichloroethylene
95-95-4 2,4,5-Trichlorophenol
88-06-2 2,4,6-Trichlorophenol
121-44-8 Triethylamine
1582-09-8 Trifluralin
540-84-1 2,2,4-Trimethylpentane
108-05-4 Vinyl acetate
593-60-2 Vinyl bromide
75-01-4 Vinyl chloride
75-35-4 Vinylidcne chloride (1,1-
Dichloroethylene)
1330-20-7 Xylenes (mixed isomers)
95-47-6 o-Xylenes
108-38-3 m-Xylenes
106-42-3 p-Xylenes
[none] Antimony Compounds
[none) Arsenic Compounds (inorganic
including arsine)
[none] Beryllium Compounds
[none] Cadmium Compounds
[none] Chromium Compounds
[none] Cobalt Compounds
[none] Coke Oven Emissions
[none] Cyanide Compounds"
[none] Glycol ethers'
[none] Lead Compounds
[none] Manganese Compounds
[none] Mercury Compounds
[none] Fine mineral fibers'
[none] Nickel Compounds
[none] Polycylic Organic Mattel
[none] Radionuclides (including
radon)*
[none] Selenium Compounds
NOTE: For all listings above which contain the word "compounds" and for glycol ethers, the following applies: Unless otherwise specified,
these listings are defined as including any unique chemical substance that contains the named chemical (i.e., antimony, arsenic, etc.) as part
of that chemical's infrastructure.
a X'CN where X = H' or any other group where a formal dissociation can occur. For example KCN or Ca(CN)2.
b On January 12,1999 (64 FR 1780), EPA proposed to modify the definition of glycol ethers to exclude surfactant alcohol ethoxylates and
their derivatives (SAED). On August 2, 2000 (65 FR 47342), EPA published the final action. This action deletes each individual com-
pound in a group called the surfactant alcohol ethoxylates and their derivatives (SAEB? faun the glycol ethers category in the list of haz-
ardous air pollutants (HAP) established by section 112(b)(l) ottfe dean* *irAF (<«&}. EPA also made conforming changes in the
definition of glycol ethers with respect to the designation of hazardbus substancesmndeT the Comprehensive Environmental Response
Compensation,, and'Liability Act (CERCLA)'..
"The following definition of the glycol etfteis Gategpry off Hazardous air pollutants applies instead of the definition set forth in 42 U.S.C.
7412(b)(l), footnote 2: Glycol ethersindtefcraorro- and! di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol R-
Where:
n= 1, 2, or 3
R= alkyi C7 or lessr or phenyl or alkyl substituted phenyl
R'= H, or alkyl C7 or less, or carboxylic acid ester, sulfate,.phosphate, nitrate, or sulfonate.
c Includes mineral fiber emissions from facilities manufacturing or processing glass, rock, or slag fibers (or other mineral derived fibers) of
average diameter. 1 micrometer or less. (Currently under review.)
d Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100°C.
(Currently under review.)'
e A type of atom whicni spontaneously undergoes radioactive decay.
5-7
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Protecting Air Quality—Protecting Air Quality
, Source Category
Table 3
Source Categories With MACT Standards
Federal Register Citation Source Category
Federal Register Citation
Fuel Combustion
Coal- and Oil-fired Electric Utility Steam
Generating Units
Combustion Turbines
Engine Test Facilities
Industrial Boilers
Institutional/Commercial Boilers
Process Heaters
Reciprocating Internal Combustion Engines
Rocket Testing Facilities
Non-Ferrous Metals Processing
Primary Aluminum Production
Primary Copper Smelting
Primary Lead Smelting
Primary Magnesium Refining
Secondary Aluminum Production
Secondary Lead Smelting
Ferrous Metals Processing
Coke G>vens: Charging, Top Side, and
Door Leaks
Coke Ovens: Pushing, Quenching and
Battery Stacks
Ferroalloys Production
Silicomanganese and Ferromanganese
Integrated Iron and Steel Manufacturing
Iron Foundries
Steel Foundries
Steel Pickling-HCl Process Facilities and
Hydrochloric Acid Regeneration Plants
Mineral Products Processing
Asphalt Processing
Asphalt Roofing Manufacturing
Asphalt/Coal Tar Application-Metal Pipes
Clay Products Manufacturing
Lame Manufacturing
Mineral Wool Production.
Portland Cement Manufacturing
Refractories Manufacturing
Taconite Iron Ore Processing
Wool Fiberglass Manufacturing
65 FR 79825CN) 12/20/00
62 FR 52383(F) 10/7/97
63 FR 19582(P) 4/20/98
64 FR 30194CF) 6/4/99
*
65 FR 15689(F) 3/23/00
60 FR 32587(F) 6/23/95
58 FR 57898(F) 10/27/93
66 FR35327(P) 7/3/01
64 FR27450(F) 5/20/00
66 FR 36835(P) 7/13/01
64 FR 33202(F) 6/22/99
64 FR 29490(F) 6/1/99
64 FR31897(F) 6/14/99
64 FR 31695(F) 6/14/99
Petroleum and Natural Gas Production and Refining
Oil and Natural Gas Production
Natural Gas Transmission and Storage
Petroleum Refineries-Catalytic Cracking
Units, Catalytic Reforming Units, and
Sulfur Recovery Units
Petroleum Refineries-Other Sources Not
Distinctly Listed
Liquids Distribution
Gasoline Distribution (Stage 1)
64FR32610(F)6/17/99
64 FR32610(F) 6/17/99
63FR48890(P)9/ll/98
60 FR 43244(F) 8/18/95
59 FR 64303(F) 12/14/94
Marine Vessel Loading Operations
Organic Liquids Distribution
(Non-Gasoline)
Surface Coating Processes
Aerospace Industries
Auto and Light Duty Truck
Flat Wood Paneling
Large Appliance
Magnetic Tapes
Manufacture of Paints, Coatings, and
Adhesives
Metal Can
Metal Coil
Metal Furniture
Miscellaneous Metal Parts and Products
Paper and Other Webs
Plastic Parts and Products
Printing, Coating, and Dyeing of Fabrics
Printing/Publishing
Shipbuilding and Ship Repair
Wood Building Products
Wood Furniture
Waste Treatment and Disposal
Hazardous Waste Incineration
Municipal Solid Waste Landfills
Off-Site Waste and Recovery Operations
Publicly Owned Treatment Works
Site Remediation
Agricultural Chemicals Production
Pesticide Active Ingredient Production
Fibers Production Processes
Acrylic Fibers/Modacrylic Fibers
Spandex Production
Food and Agriculture Processes
Manufacturing of Nutritional Yeast
Solvent Extraction for Vegetable Oil
Production
Vegetable Oil Production
Pharmaceutical Production Processes
Pharmaceuticals Production
60 FR 48399(F) 9/19/95
60FR45956(F)9/1/15
*
64 FR63025(N) 11/18/99
65FR81134(P) 12/22/00
59 FR 64580(F) 12/15/94
65 FR44616(P) 7/18/00
65 FR 55332CP) 9/13/00
61 FR 27132(F) 5/30/96
60 FR 64330(F) 12/16/96
*
60 FR 62930(F) 12/7/95
64 FR 52828(F) 9/30/99
65 FR66672(P) 11/7/00
61 FR 34140(F) 7/1/96
64 FR 57572(F) 10/26/99
64 FR33549(F) 6/23/99
64 FR 34853(F) 6/30/99
65 FR 76408(P) 12/6/00
66FR27876(F)5/21/01
66 FR 19006(F) 4/12/01
66 FR 8220(N) 1/30/01
66 FR40121(F) 6/1/99
Polymers and Resins Production
Acetal Resins Production 64 FR 34853(F) 6/30/99
Acrylonitrile-Butadiene-Styrene Production 61 FR 48208(F) 9/12/96
Alkyd Resins Production *
Amino Resins Production 65 FR 3275(F) 1/20/00
Boat Manufacturing 66 FR 44218(F) 8/22/01
Butyl Rubber Production 61 FR 46906(F) 9/5/96
Cellulose Ethers Production 65 FR 52166(P) 8/28/00
Epichlorohydrin Elastomers Production 61 FR 46906(F) 9/5/96
5-8
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Protecting Air Quality—Protecting Air Quality
Table 3
Source Categories With MACT Standards (cont.)
Sburcel Cfeteg
JFecierll Register-QtatMiX Sojirce:Gajeg6ry
Federal;Register'Citation,"
Epoxy Resins Production
Ethylene-Propylene Rubber Production
Flexible Polyurethane Foam Production
Hypalon (tm) Production
Maleic Anhydride Copolymers Production
Methyl Methacrylate-Aciylonitrile
Butadiene-Styrene Production
Methyl Methacrylate-Butadiene-Styrene
Terpolymers Production
Neoprene Production
Nitrile Butadiene Rubber Production
Nitrile Resins Production
Non-Nylon Polyamides Production
Phenolic Resins Production
Polybutadiene Rubber Production
Polycarbonates Production
Polyester Resins Production
Polyether Polyols Production
Polyethylene Terephthalate Production
Polymerized Vinylidene Chloride
Production
Polymethyl Methacrylate Resins Production
Polystyrene Production
Polysulfide Rubber Production .
Polyvinyl Acetate Emulsions Production
Polyvtnyl Alcohol Production
Polyvinyl Butyral Production
Polyvinyl Chloride and Copolymers
Production
Reinforced Plastic Composites Production
Styrene-Acrylonitrile Production
60 FR 12670(F) 3/8/95
61 FR 46906CF) 9/5/96
63 FR 53980(F) 10/7/98
61 FR 46906(F) 9/5/96
*
61 FR48208CF) 9/12/96
61 FR 48208CF) 9/12/96
61 FR 46906(F) 9/5/96
61 FR 46906(F) 9/5/96
61 FR 48208(F) 9/12/96
60 FR 12670(F) 3/8/95
65 FR 3275(F) 1/20/00
61 FR46906(F) 9/5/96
64 FR 34853CF) 6/30/99
*
64 FR 29420(F) 6/1/99
61 FR48208(F) 9»296
61 FR48208(F) 9/12/96
61 FR46906(F) 9/5/96
Styrene-Butadiene Rubber and Latex
Production
Production of Inorganic Chemicals
Ammonium Sulfate Production-
Caprolactam By-Product Plants
Carbon Black Production
Chlorine Production
Cyanide Chemicals Manufacturing.
Fumed Silica Production
Hydrochloric Acid Production
Hydrogen Fluoride Production
Phosphate Fertilizers Production
Phosphoric Acid Manufacturing
Production of Organic Chemicals
Ethylene Processes
65 FR 76958(P) 12/8/00
66 FR 40324(P) 8/2/01
61 FR48208CF) 9/12/96
61 FR 46906(F) 9/5/96
65 FR 76408CP) 12/6/00
65 FR 76408(P)' 12/6700
64 FR 63025(N) ll/18/9ff
*
64 FR 3-4853(F) 6/30/99
64 FR 3135H(F) 6/10/99
64 FR 31358CF) 6/10/99
65 FR 76408(P) 12/6/00
Quaternary Ammonium Compounds
Production
Synthetic Organic Chemical
Manufacturing
Miscellaneous Processes
Benzyltrimethylammonium Chloride
Production
Carbonyl Sulfide Production
Chelating Agents Production
Chlorinated Paraffins Production
Chromic Acid Anodizing
Combustion Sources at Kraft, Soda, and
Sulfite Pulp and Paper Mills
Commercial Dry Cleaning
(PerchloroethyleneXTransfer Machines
Commercial Sterilization Facilities
Decorative Chromium Electroplating,
Ethylidene Norbornene Production
Explosives Production
Flexible Polyurethane Foam Fabrication
Operations
Halogenarrf Solvent Cleaners
Hard Chromium Electroplating
Hydrazine Production
Industrial Cleaning (Perchloroethylene)-
Dry-to-Dry machines
Industrial Dry Cleaning
(Perchloroethylene)-Transfer Machines
Industrial Process Cooling Towers
Leather Finishing Operations
Miscellaneous Viscose Processes
OBPA/l,3-Diisocyanate Production
Paint Stripping Operations
Photographic Chemicals Production
Phthalate Plasticizers Production
Plywood, and Composite Wood Products
Pulp and Paper Production
Rubber Chemicals Manufacturing
Rubber Tire-Manufacturing
Semiconductor Manufacturing
Symmetrical Tetrachloropyridine
Production:
Tetrahydrobenzaldehyde Manufacture
Wfet-Formed Fiberglass Mat Production
59 FR 19402(F) 4/22/94
60 FR04948(F) 1/25/95
66 FR3180(F) 1/12/01
58 FR 49354(F) 9/22/93
59 FR 62585(F) 12/6/94
60 FR 04948CF) 1/25/95.
66 FR41718(P) 8/8/01
59 FR 6180KF) 12/2/94
60 FR 04948(F) 1/25/95
58 FR 49354(F) 9/22/93
58 FR49354(F) 9/22/93
59 FR46339CF) 9/8/94
67 FR 9155CF) 2/27/02
65 FR 52166CF) 8/28/00
65 FR80755(F) 12/22/00
*
63 FR62414(P) 10/18/00
63 FR 26078(F) 5/21/98
65 FR 34277CP) 5/26/00
This table contains final rules (F), proposed rules'(P), and notices (N) promulgated as of February 2002. It does
not identify corrections or clarifications to rules. An * denotes sources required by Section 112 of the CAA to have
MACT standards by 11/15/00 for which proposed rules are being prepared but have not yet been published.
5-9
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Protecting Air Quality—Protecting Air Quality
D. Title V Operating
Permits
For many facilities, the new federal oper-
ating permit program established under Title
V of the CAA will cover all sources of air-
borne emissions.6 Generally, it requires a per-
mit for any facility emitting or having the
potential to emit more than 100 tpy of any
air pollutants though lower thresholds apply
in non-attainment areas.7 Permits are also
required for all sources subject to MACT or
NSPS standards, the Title IV acid rain pro-
gram, and new source review permits under
Parts C and D of Title Y All airborne emis-
sion requirements that apply to an industrial
facility, including emission limitations, oper-
ational requirements, monitoring require-
ments, and reporting requirements, will be
incorporated in its operating permit. A Title
V permit provides a vehicle for ensuring that
existing air quality control requirements are
appropriately applied to facility emission
units.
Under the new program, operating permits
that meet federal requirements will generally
be issued by state agencies. In developing
individual permits, states can determine
whether to explicitly apply emission limita-
tions and controls to waste management
units. See Section F of this chapter (A
Decision Guide to Applicable CAA
Requirements), and consult with federal,
state, and local air program staff to determine
if your waste management unit is subject to
airborne emission limits and controls under
CAA regulations. Listings of EPA regional and
state air pollution control agencies can be
obtained from the States and Territorial Air
Pollution Program Administrators (STAPPA)
&r Association of Local Air Pollution Control
Officials (ALAPCO). STAPPA/ALAPCOs Web
site is .
E. Federal Airborne
Emission Regulations for
Solid Waste
Management Activities
While EPA has not established airborne .
emission regulations for industrial waste man-
agement units under RCRA, standards devel-
oped for hazardous waste management units
and municipal solid waste landfills (MSWLFs)
can serve as a guide in evaluating the need for
controls at specific units.
1. Hazardous Waste
Management Unit Airborne
Emission Regulations
Under Section 3004(n) of RCRA, EPA
established standards for the monitoring and
control of airborne emissions from hazardous
waste treatment, storage, and disposal facili-
ties. Subparts AA, BB, and CC of 40 CFR Part
264 address VOC releases from process vents,
equipment leaks, tanks, surface impound-
ments, and containers. Summaries of
Subparts AA, BB, and CC are provided in the
text box on the next page.
2. Municipal Solid Waste Landfill
Airborne Emission Regulations
On March 12, 1996, EPA promulgated air-
borne emission regulations for large new and
existing MSWLFs.8 These regulations apply to
all new MSWLFs constructed or modified on
5-10
6 Federal Operating Permit Regulations were promulgated as 40 CFR Part 71 on July 1, 1996 and
amended on February 19, 1999 to cover permits in Indian Country and states without fully approved
Title V programs.
7 Under CAA Section 302(g), "air pollutant" is defined as any pollutant agent or combination of agents,
including any physical, chemical, biological, or radioactive substance or matter which is emitted into
or otherwise enters the ambient air.
8 61 FR 9905; March 12, 1996, codified at 40 CFR Subpart WWW and CC (amended 63 FR 32750,
June 16, 1998).
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Protecting Air Quality—Protecting Air Quality
or after May 30, 1991, and to
existing landfills that have
accepted waste on or after
November 8, 1987. In addition
to methane, MSWLFs potentially
emit non-methane organic com-
pounds (NMOCs) in the gases
generated during waste decom-
position, as well as in combus-
tion of the gases in control
devices, and from other sources,
such as dust from vehicle traffic
and emissions from leachate
treatment facilities or mainte-
nance shops. Under the regula-
tions, any affected MSWLF that
emits more than 50 Mg/yr (55
tpy) of NMOCs is required to
install controls.
Best demonstrated technology
requirements for both new and
existing municipal landfills pre-
scribe installation of a well-
designed and well-operated gas
collection system and a control
device. The collection system
should be designed to allow
expansion for new cells that
require controls. The control
device (presumed to be a com-
bustor) must demonstrate either
an NMOC reduction of 98 per-
cent by weight in the colfeetedi
gas or an outlet NMOC concen-
tration of no more than 20 parts
per million by volume (ppmv).
3. Offsite Waste and
Recovery
Operations NESHAP
On July 1, 1996, EPA estab-
lished standards for offsite waste
and recovery operations
Summary of Airborne Emission
Regulations for Hazardous Waste
Management Units
Subpart AA regulates organic emissions from
process vents associated with distillation, fractionation,
thin film^evaporation, solvent extraction, and air or
stream stripping operations (40 CFR §§264.1030- '
1036) Subpart AA only applies to these types of units
^ managing hazardous waste streams with organic con- -
'centratioh levels of at least 10 parts per million by *
weight (ppmw). Subpart AA regulations^require facili-
ties with covered process vents to either reduce total ,
organic emissions from" all .affected process vents at the"
facility to below 3 Ib/h and 3.1 tons/yr, or reduce emis-
sions from all process vents by'95 percent through the „
use of a control device, such as a"closed-vent system,
- vapor recovery,uhitr flare, or other combustion unit.
Subpart BB sets inspection and maintenance
requirements for equipment, such as valves, pumps,
compressors, pressure relief devices, sampling connec-
tion systems, open-ended valves or lines, flanges, or
control devices that contain or contact hazardous
wastes with organfc concentrations of at least 10 per-
cent by weight (40 CFR §§264.1050-1065). Subpart
BB does not establish numeric criteria for reducing
emissions,- it simply establishes monitoring, leak detec-
tion, and repair requirements. -
/ ^ > f
Subpart CC establishes controls on tanks, surface '
impoundments/and containers in which, hazardous
waste has,been placed^ ( 40 CFR §§264.1080-1091). It
applies emly to units containing hazardous waste with
an average organic concentration greater than 500
ppmw Units managing hazardous waste that has been
treated to reduce the concentrations of ofganics by 95
percent are exempt. Non-exempt, surface impound-
ments must have either a rigid cover or, if wasres are
not agitated or heated, a floating membrane cover.
Closed vent systems are required to control the emis-
sions from covered surface impoundments. These con-
trol systems must achieve the same 95 percent emission
reductions descnbed above under Subpart AA.
5-11
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Protecting Air Quality—Protecting Air Quality
(OSWRO) that emit HAPs.9 To be covered by
OSWRO, a facility must emit or have the
potential to emit at least 10 tpy of any single
HAP or at least 25 tpy of any combination of
HAPs. It must receive waste, used oil, or used
solvents from off site that contain one or
more HAPs.10 In addition, the facility must
operate one of the following: a hazardous
waste treatment, storage, or disposal facility;
RCRA-exempt hazardous wastewater treat-
ment operation; nonhazardous wastewater
treatment facility other than a publicly owned
treatment facility; or a RCRA-exempt haz-
ardous waste recycling or reprocessing opera-
tion, used solvent recovery operation, or used
oil recovery operation.
OSWRO contains MACT standards to
reduce HAP emissions from tanks, surface
impoundments, containers, oil-water separa-
tors, individual drain systems, other material
conveyance systems, process vents, and
equipment leaks. For example, OSWRO
establishes two levels of air emission controls
for tanks depending on tank design capacity
and the maximum organic HAP vapor pres-
sure of the offsite material in the tank. For
process vents, control devices must achieve a
minimum of 95 percent organic HAP emis-
sion control. To control HAP emissions from
equipment leaks, the facility must implement
leak detection and repair work practices and
equipment modifications for those equipment
components containing or contacting offsite
waste having a total organic HAP concentra-
tion greater than 10 percent by weight (see
40 CFR 63.683(d) cross ref. to 40 CFR
63.680 (c) (3)).
F. A Decision Guide to
Applicable CAA
Requirements
The following series of questions, summa-
rized in Figure 1, is designed to help you iden-
tify CAA requirements that might apply to a
facility This will not give you definitive
answers, but can provide a useful starting point
for consultation with federal, state, or local per-
mitting authorities to determine which require-
ments apply to a specific facility and whether
such requirements address waste management
units at die facility. If a facility is clearly not
subject to CAA requirements, assessing poten-
tial risks from VOC emissions at a waste man-
agement unit using the IWAIR or a site-specific
risk assessment is recommended.
The following steps provide a walk
through of this evaluation process:
7. Determining Emissions From
the Unit
a) Determining VOC's present in the
waste (waste characterization). Then
assume all the VOC's are emitted
from the unit, or
b) Estimating emissions using an emis-
sions model. This also requires waste
characterization. The CHEMDAT8
model is a logical model for these
types of waste units. You can use the
EPA version on the Internet or the
one contained in the IWAIR model-
ing tool for the Guide, or
c) Measuring emissions from the unit.
While this is the most resource inten-
sive alternative, measured data will
provide the most accurate information.
5-12
' 61 FR 34139; July 1, 1996, as amended, 64 FR 38970 0uly 20, 1999) and 66 FR 1266 (January 8,
2001).
10 OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAA
Section 112 list.
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Protecting Air Quality—Protecting Air Quality
Figure 1. Evaluating VOC Emission Risk
[ Characterize waste for potential air emissions I
Is the unit part
of an industrial facility
which is subject to a CAA Title V
operating permit by virtue of being:
a. considered a major source; or
b. subject to NSPSs; or
c. considered a major source of HAPs and subject to
NESHAP or MAC! standards; or
d. subject to the acid rain program; or
e. a unit subject to the
OSWRO NESHAP?
Facility is subject
Does
the waste
contain any of the 95
listed contaminants
in IWAIR?
Conduct a risk evaluation using either:
a. Industrial Waste Air
Model (IWAIR)
b. Site-specific risk
assessment
i^ou! should conduct a more site-
specific risk assessment
la
tfe total'
risk for the unit
acceptable?
You should reduce risk to accept-
able levels using treatment, con-
trols, or waste minimization
You should operate the unit in accordance with the
recommendations of this guidance.
5-13
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Protecting Air Quality—Protecting Air Quality
2. Is the Waste Management
Unit Part of an Industrial
Facility That Is Subject to a
CAA Title V Operating
Permit?
A facility is subject to a Title V operating
permit if it is considered a major source of air
pollutants, or is subject to a NSPS, NESHAP,
or Title IV acid rain provision." As part of the
permitting process, the facility should develop
an emissions inventory Some states have
additional permitting requirements. If a facili-
ty is subject to a Title V operating permit, all
airborne emission requirements that apply to
an industrial facility, including emission limi-
tations as well as operational, monitoring, and
reporting requirements, will be incorporated
in its operating permit. You should consult
with appropriate federal, state, and local air
program staff to determine whether your
waste management unit is subject to air emis-
sion limits and controls.12
If you answer yes to any of the questions
in items a. through e. below, the facility is
subject to a Title V operating permit. Consult
with the appropriate federal, state, and/or
local permitting authority.
Whether or not emissions from waste
management unit(s) will be specifically
addressed through the permit process
depends on a number of factors, including
the type of facility and CAA requirements
and state permitting resources and priorities.
It is prudent, when there are no applicable
air permit requirements, to assess whether
there might be risks associated with waste
management units and to address these
potential risks.
If you answer no to all the questions
below, continue to Step 3.
Stationary source is defined as any
building, structure, facility, or installation
that emits or may emit any regulated air
pollutant or any hazardous air pollutant
listed under Section 112 (b) of the Act.
An air pollutant is defined as any air pol-
lution agent or combination of agents,
including a physical, chemical, biological,
radioactive substance or matter which is
emitted into or otherwise enters die ambi-
' ent air.
a. Is the facility considered a major
source?
If the facility meets any of the following
three definitions, it is considered a major
source (under 40 CFR § 70.2) and subject to
Title V operating permit requirements.
i. Any stationary source or group of
stationary sources that emits or has
the potential to emit at least 100 tpy
of any air pollutant.
ii. Any stationary source or group of
stationary sources that emits or has
the potential to emit at least 10 tpy
of any single HAP or at least 25 tpy
of any combination of HAPs.
iii. A stationary source or group of sta-
tionary sources subject to the nonat-
tainment area provisions of CAA Title
I that emits, or has the potential to
emit, above the threshold values for
its nonattainment area category. The
nonattainment area category and the
sources emission levels for VOCs and
NOX, particulate matter (PM-10), and
carbon monoxide (CO) determine
whether the stationary source meets
the definition of a "major source."
For nonattainment areas, stationary
sources are considered "major
5-14
11 EPA can designate additional source categories subject to Title V operating permit requirements.
" Implementation of air emission controls can generate new residual waste. Ensure that these wastes are
managed appropriately, in compliance .with-state requirements and consistent with the Guide.
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Protecting Air Quality—Protecting Air Quality
sources" if they emit or have the
potential to emit at least the levels
found in Table 4 below.
If yes, the facility is subject to a Title V
operating permit. Consult with the appropri-
ate federal, state, and/or local permitting
authority.
If no, continue to determine whether the
facility is subject to a Title V operating permit.
b. Is the facility subject to NSPSs?
Any stationary source subject to a standard
of performance under 40 CFR Part 60 is sub-
ject to NSPS. (A list of NSPSs can be found in
Table 1 above.)
If yes, the facility is subject to a Title V
operating permit. Consult widi the appropri-
ate federal, state, and/or local permitting
authority.
If no, continue to determine if the facility
is subject to a Title V operating permit.
c. Is the facility a major source of
HAPs as defined by Section 112 of
CAA and subject to a NESHAP or
MACT standard?
Under Title V of CAA, an operating permit
is required for all facilities subject to a MACT
standard. NESHAPs or MACT standards are
national standards to reduce HAP emissions.
Each MACT standard specifies particular
operations, processes, and/or wastes that are
covered. EPA has identified approximately
170 source categories and subcategories that
are or will be subject to MACT standards.
(Table 3 above lists the source categories for
which EPA is required to promulgate MACT
standards.) MACT standards have been or
will be promulgated for all major source cate-
gories of HAPs and for certain area sources.
If yes, the facility should be permitted
under CAA Title V Consult with the appro-
priate federal, state, and/or local permitting
authority.
If no, continue to determine if the facility
must obtain a Title V operating permit.
d.
Table 4.
Major 'Source Determination in Nonattainment Areas
Nonattainment
Area Category13
Marginal or
Moderate
Serious
Severe
Extreme
VOCs or NOX
100 tpy
50 tpy
25 tpy
10 tpy
PM-10
100 tpy
70 tpy
—
—
CO
100 tpy
50 tpy
—
—
Is the facility subject to the acid rain
program under Title IV of CAA?
If a facility, such as a
fossil-fuel fired power
plant, is subject to
emission reduction
requirements or limita-
tions under the acid
rain program, it must
obtain a Title V operat-
ing permit (40 CFR §
72.6). The acid rain
program focuses on the
reduction of annual sul-
fur dioxide and nitro-
gen oxides emissions.
" The nonattainment categories are based upon the severity of the area's pollution problems. The four cate-
gories for VOCs and NOX range from Moderate to Extreme. Moderate areas are the closest to meeting the
attainment standard, and require the least amount of action. Nonattainment areas with more serious air
quality problems must implement various control measures. The worse the air quality, the more controls
areas will have to implement. PM-10 and CO have only two categories, Moderate and Serious.
5-15
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Protecting Air Quality—Protecting Air Quality
A major source under Title III is
defined as any stationary source or
group of stationary sources that emits or
has the potential to emit at least 10 tpy
of any single hazardous air pollutant
(HAP) or at least 25 tpy of any combina-
tion of HAPs. •;...:.-•:
An area source is any stationary
source which is not a major source but
which might be subject to controlsvArea
sources represent a collection of facilities
and emission points for a specific geo-
graphic area. Most area sources are ^
small, but the collective volume of large
numbers of facilities can be a concern in
densely developed areas, such as urban
neighborhoods and industrial areas.-
Examples of areas sources subject to
MACT standards include chromic acid
anodizing, commercial sterilization facil-
ities, decorative chromium electroplat-
ing, hard chromium electroplating,
secondary lead smelting, and halogenat-
ed solvent cleaners.
HAPs are any of the 188 pollutants
listed in Section 112(b) of CAA. (Table 2
above identifies the 188 HAPs.)
If yes, the facility must obtain a Title V
permit. Consult with the appropriate federal,
state, and/or local permitting authority.
When you consult with the appropriate
permitting authority, it is important to clarify
whether waste management units at the facil-
ity are addressed by the requirements. If
waste management units will not be
addressed through the permit process, you
should evaluate VOC emission risks.
If no, continue to determine if the facility
must obtain a Title V operating permit.
e. Is the waste management unit
subject to the OSWRO NESHAP?
This is just an example of the types
of questions you will need to
answer to determine whether a
NESHAP or MACT standard covers
your facility.
To be covered by the OSWRO standards,
your facility must meet all these conditions:
i. Be identified as a major source of
HAP emissions.
ii. Receive waste, used oil, or used sol-
vents (subject to certain exclusions,
40 CFR 63.680 (b) (2)) from off site
that contain one or more HAPs.1'1'
iii. Operate one of the following six
types of waste management or recov-
ery operations (see 40 CFR 63.680
(a) (2)):
• Hazardous waste treatment, storage,
or disposal facility.
• RCRA-exempt hazardous wastewater
treatment operation.
• Nonhazardous wastewater treatment
facility other than a publicly owned
treatment facility.
• RCRA-exempt hazardous waste recy-
cling or reprocessing operation.
• Used solvent recovery operations.
• Used oil recovery operations.
If yes, the unit should be covered by the
OSWRO standards and Title V permitting.
Consult with the appropriate federal, state,
and/or local permitting authority.
If no, it is highly recommended that you
conduct an air risk evaluation as set out in
step 3.
5-16
" OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAA
Section 112 list.
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Protecting Air Quality—Protecting Air Quality
a.
b.
Conducting a Risk Evaluation
Using One of the Following
Options:
Using IWAIR included with the
Guide if your unit contains any of the
95 contaminants that are covered in
the model.
Initiating a site-specific 'risk assess-
ment for individual units. Total all
target constituents from all applicable
units and consider emissions from
other sources at the facility as well.
II. Assessing Risk
Air acts as a medium for the transport of
airborne contamination and, therefore, con-
stitutes an exposure pathway of potential
concern. Models that can predict the fate and
transport of chemical emissions in the atmos-
phere can provide an important tool for eval-
uating and protecting air quality. The
Industrial Waste Air Model (IWAIR) included
in the Guide was developed to assist facility
managers, regulatory agency staff, and the
public in evaluating inhalation risks from
waste management unit emissions. Although
IWAIR is simple to use, it is still essential to
understand the basic concepts of atmospheric
modeling to be able to-interpret the results
and understand the nature of any uncertain-
ties. The purpose of this section is to provide
general information on the atmosphere,
chemical transport in the atmosphere, and
the risks associated with inhalation of chemi-
cals so you can understand important factors
to consider when performing a risk assess-
ment for the air pathway.
From a risk perspective, because humans
are continuously exposed to air, the presence
of chemicals in air is important to consider in
any type of assessment. If chemicals build up
to high concentrations in a localized area,
human health can be compromised. The con-
centration of chemicals in a localized area and
the resulting air pollution that can occur in the
atmosphere is dependent upon the quantity
and the rate of the emissions from a source
and the ability of the atmosphere to disperse
the chemicals. Both meteorological and geo-
graphic conditions in a local area will influ-
ence the emission rate and subsequent
dispersion of a chemical. For example, the
meteorologic stability of the atmosphere, a fac-
tor dependent on air temperature, influences
whether the emission stream will rise and mix
with a larger volume of air (resulting in the
dilution of pollutants) or if the emissions
stream will remain close to the ground. Figure
2 is a conceptual diagram of a waste site illus-
trating potential paths of human exposure
through air.
A. Assessing Risks Associated
with Inhalation of
Ambient Air
In any type of risk assessment, there are
basic steps that are necessary for gathering
and evaluating data. An overview of some of
these steps is presented in this section to
assist you in understanding conceptually the
information discussed in the IWAIR section
(Section B). The components of a risk assess-
ment that are discussed in this section are:
identification of chemicals of concern, source
characterization, exposure assessment, and
risk characterization. Each of these steps is
described below as it applies specifically to
risk resulting from the inhalation of organic
chemicals emitted from waste management
units to the ambient air.
Identification of Chemicals of Concern
A preliminary step in any risk assessment
is the identification of chemicals of concern.
These are the chemicals present that are
anticipated to have potential health effects as
5-17
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Protecting Air Quality—Protecting Air Quality
Figure 2. Conceptual Site Diagram
Vfrd
. f^ ^ PwSaft*
£<—jJ .-<•"."
a result of their concentrations or toxicity
factors. An assessment is performed for a
given source, to evaluate chemical concentra-
tions and toxicity of different chemicals.
Based on these factors along with potential
mechanisms of transport and exposure path-
ways, the decision is made to include or
exclude chemicals in the risk assessment.
Source Characterization
In this step, the critical aspects of the
source (e.g., type of WMU, size, chemical
concentrations, location) are necessary to
obtain. When modeling an area source, such
as those included in the Guide, the amount
of a given chemical that volatilizes and dis-
perses from a source is critically dependent
on the total surface area exposed. The source
characterization should include information
on the surface area and elevation of the unit.
The volatilization is also dependent on other
specific attributes related to the waste man-
agement practices. Waste management prac-
tices of importance include application
frequency in land application units and the
degree of aeration that occurs in a surface
impoundment. Knowledge of the overall con-
tent of the waste being deposited in the
WMU is also needed to estimate chemical
volatilization. Depending on its chemical
characteristics, a chemical can bind with the
other constituents in a waste, decreasing its
emissions to the ambient air. Source charac-
terization involves defining each of these key
parameters for the WMU being modeled. The
accuracy of projections concerning volatiliza-
tion of chemicals from WMUs into ambient
air is improved if more site-specific informa-
tion is used in characterizing the source.
Exposure Assessment
The goal of an exposure assessment is to
estimate the amount of a chemical that is
available and is taken in by an individual,
typically referred to as a receptor. An expo-
sure assessment is performed in two steps: 1)
the first step uses fate and transport model-
ing to determine the chemical concentration
in air at a specified receptor location and, 2)
the second step estimates the amount of the
chemical the receptor will intake by identify-
ing life-style activity patterns. The first step,
the fate and transport modeling, uses a com-
bination of an emission and dispersion model
to estimate the amount of chemical that indi-
viduals residing or working within the vicini-
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Protecting Air Quality—Protecting Air Quality
Figure 3. Emissions from a WMU
ty of the source are exposed to through
inhalation of ambient air. When a chemical
volatilizes from a WMU into the ambient air,
it is subjected to a number of forces that
result in its diffusion and transport away from
the point of release.
In modeling the movement of the volatile
chemical away from the WMU, it is often
assumed that the-chemical behaves as a
plume (i.e., the chemical is continuously
emitted into the environment) whose move-
ment is modeled to produce estimated air
concentrations at points of interest. This
process is illustrated in Figure 3.
The pattern of diffusion and movement of
chemicals that volatilize .from WMUs depends
on a number of interrelated factors. The ulti-
mate concentration and fate of emissions to
the air are most significantly impacted by
, three meteorologic conditions: atmospheric
stability, wind speed, and wind direction.
These meteorologic factors interact to deter-
mine the ultimate concentration of a pollu-
tant in a localized area.
• Atmospheric stability: The stability
of-the atmosphere is influenced by
the vertical temperature structure of
• the air above the emission source. In
a stable environment, there is little or
no movement of air parcels, and,
consequently, little or no movement
and mixing of contaminants. In such
a stable air environment, chemicals
become "trapped" and unable to
move. Conversely, in an unstable
environment there is significant mix-
ing and therefore greater dispersion
and dilution of the plume.15
Prevailing wind patterns and their
interaction with land features: The
nature of the wind patterns immedi-
ately surrounding the WMU can sig-
nificantly impact the local air
concentrations of airborne chemicals.
Prevailing wind patterns combine
with topographic features such as
hills and buildings to affect the
movement of the plume. Upon
release, the initial direction that emis-
sions will travel is the direction of the
wind. The strength of the wind will
determine how dilute the concentra-
tion of the pollutant will be in that
direction. For example, if a strong
wind is present at the time the pollu-
tants are released, it is likely the pol-
lutants will rapidly leave the source
and become dispersed quickly into a
large volume of air.
5 An example of an unstable air"environment is one in which the sun shining on the earths surface has
resulted in warmer air at the earths surface. This warmer air will tend to rise, displacing any cooler air
that is on top of it. As these air parcels essentially switch places, significant mixing occurs.
5-19
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Protecting Air Quality—Protecting Air Quality
Figure 4. Forces That Affect Contaminant Plumes.
BuFltflng
Wet Deposition
Dry Dflposjltlorti
,^ ~S""f"«™^__
phQfadh&rnlcal /
- •*+*****—*»•
^v*..
Thermal
Mixing
,^*^T^""*»«»«'StWl-W
In addition to these factors affecting the
diffusion and transport of a plume away from
its point of release, the concentration of spe-
cific chemicals in a plume can also be affect-
ed by depletion. As volatile chemicals are
transported away from the WMU, they can
be removed from the ambient air through a
number of depletion mechanisms including
wet deposition (the removal of chemicals due
to precipitation) and dry deposition (the
removal of chemicals due to the forces of
gravity and impacts of the plume on features
such as vegetation). Chemicals can also be
transformed chemically as they come in con-
tact with the sun's rays (i.e., photochemical
degradation). Figure 4 illustrates the forces
acting to transport and deplete the contami-
nant plume.
Because the chemicals being considered in
IWAIR are volatiles and semi-volatiles and the
distances of transport being considered are
relatively short, the removal mechanisms
shown in the figure are likely to have a rela-
tively minor effect on plume concentration
(both wet and dry deposition have significant-
ly greater effects on airborne particulates).
Once the constituent's ambient outdoor
concentration is determined, the receptor's
extent of contact with the pollutant must be
characterized. This step involves determining
the location and activity patterns relevant to
the receptor being considered. In IWAIR, the
receptors are defined as residents and work-
ers located at fixed distances from the WMU,
and the only route of exposure considered
for these receptors is the inhalation of
volatiles. Typical activity patterns and body
physiology of workers and residents are used
to determine the intake of the constituent.
Intake estimates quantify the extent to which
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Protecting Air Quality—Protecting Air Quality
the individual is exposed to the contaminant
and are a function of the breathing rate,
.exposure-concentration, exposure duration,
exposure frequency, exposure averaging time
(for carcinogens), arid body weight..
Estimated exposures are presented in terms of
the mass of the chemical per kilogram of
receptor body weight per day.
Risk Characterization
The concentrations that an individual takes
into his or her body that were determined dur-
ing the exposure assessment phase are com-
bined with toxicity values to generate risk
estimates. Toxicity values used in IWA1R
include inhalation-specific cancer slope factors
(CSFs) for carcinogenic effects and reference
concentrations (RfCs) for noncancer effects. •
These are explained in the General Risk
Section in Chapter 1—Understanding Risk
and Building Partnerships. Using these toxicity
values, risk estimates are generated for carcino-
genic effects and noncancer effects: Risk esti-
mates for carcinogens are summed by 1WAIR.
B. IWAIR Model
IWAIR is an interactive computer program
with three main components: an emissions.
model; a dispersion model to estimate fate
and transport of constituents through the
atmosphere and determine ambient air con-
centrations at specified receptor locations;
and a risk model to calculate either the risk
to exposed individuals or the waste con-
stituent concentrations that can be protective-
ly managed in the unit. To operate, the
program requires only a limited amount of
site-specific information, including facility
location, WMU characteristics, waste charac-
teristics, and receptor information. A brief
description of each component follows. The
IWAIR Technical Background Document (U.S.
EPA, 2002a)contains a more detailed explana-
tion of each.
1. Emissions Model
The emissions model uses waste character-
ization, WMU, and facility information to -
. estimate emissions ior 95 constituents that
are identified in Table 5. The emission model
selected for incorporation into IWAIR is EPA's
CHEMDAT8 model. The entire'CHEMDATS
model is run as the emission component of
the IWAIR model. CHEMDAT8 has under-
gone extensive review by both EPA and
industry representatives and is publicly avail-
able from EPA's Web page, .
To facilitate emission modeling with
CHEMDAT8, IWAIR prompts the user to pro-
vide the required waste- and unit-specific
data. Once these data are entered, the model
calculates and displays chemical-specific
emission rates. If users decide not to develop
or use the CHEMDAT8 rates, they can enter
their own site-specific emission rates (g/m2-s).
2. Dispersion Model
IWAIR's second modeling component esti-
mates dispersion of volatilized contaminants
and determines air concentrations at specified
receptor locations, using default dispersion
factors developed with EPA's Industrial
Source Complex, Short-Term Model, version
3 (ISCST3). ISCST3 was run to calculate dis-
persion for a standardized unit emission rate
(1 ug/m2 - s) to obtain a unitized air concen-
tration (UAC), also called-a dispersion factor,
which is measured in u/m3 per pg/m2-s. The
total air concentration estimates are then
developed by multiplying the constituent-
specific emission rates derived from CHEM-
DAT8 (or from another source) with a
site-specific dispersion factor. Running
ISCST3 to develop a new dispersion factor
for each location/WMU is very tirrie consum-
ing and requires extensive meteorological
data and technical expertise. Therefore
IWAIR incorporates default dispersion factors
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Protecting Air Quality—Protecting Air Quality
Table 5. Constituents Included in IWAIR
Chemical Compound Name
Abstracts
(CAS) - _ :•-... :;
Number , ;
Chemical; Compound Name
Abstracts /
(CAS) ;: ; ,V ,- '.;.
Number ' , ;
75-07-0 Acelaldehyde
67-64-1 Acetone
75-05-8 Acetonitrile
107-02-8 Acrolein '••
79-06-1 Acrylamide
79-10-7 Acrylic acid
107-13-1 Acrylonitrile
107-05-1 Allyl chloide
62-53-3 Aniline
71-43-2 Benzene
92-87-5 Benzidine
50-32-8 Benzo(a)pyrene
75-27-4 Bromodichloromethane
106-99-0 Butadine, 1,3-
75-15-0 Carbon disulfide
56-23-5 Carbon tetrachloride
103-90-7 Chlorobenzene
124-48-1 , Chlorodibromomethane
67-66-3 Chloroform
95-57-8 Chloropphenol, 2-
126-99-8 Chloroprene
1006-10-15 cis-l,3-Dichloropropylene
1319-77-3 Cresols (total)
98-82-8 Cumene
108-93-0 Cyclohexanol
96-12-8 Dibromo-3-chloropropane, 1,2-
75-71-8 Dichlorodifluorometliane
107-06-2 Dichloroethane, 1,2-
75-35-4 Dichloroethylene, 1,1-
78-87-5 Dichloropropane, 1,2-
57-97-6 Dimethylbenz[a]anthracene , 7,12-
95-65-8 Dimethylphenol, 3,4-
121-14-2 Dinitrotoluene, 2,4-
123-91-1 Dioxane, 1,4-
122-66-7 Diphenylhydrazine, 1,2-
106-89-8 Epichlorohydrin
106-88-7 Epoxybutane, 1,2-
11-11-59 Ethoxyethanol acetate, 2-
110-80-5 Ethoxyethanol, 2-
100-41-4 Ethylbenzene
106-93-4 Ethylene dibromide
107-21-1 Ethylene glycol
75-21-8 Ethylene oxide
50-00-0 Formaldehyde
98-01-1 Furfural
87-68-3 Hexachloro-l,3-butadiene
118-74-1 Hexchlorobenzene
77-47-4 Hexachlorocyclopentadine
67-72-1 Hexachloroethane
78-59-1 Isophorone
7439-97-6 Mercury
67-56-1 Methanol
110-49-6 Methoxyethanol acetate, 2- .
109-86-4 Methoxyethanol, 2-
74-83-9 Methyl bromide
74-87-3 Methyl chloride
78-93-3 Methyl ethyl ketone
108-10-1 Methyl isobutyl ketone
80-62-6 - Methyl methacrylate
1634-04-4 Methyl tert-butyl ether
56-49-5 Methylcholanthrene, 3-
75-09-2 Methylene chloride
68-12-2 N-N-Dimethyl formamide
91-20-3 Naphthalene
110-54-3 n-Hexane
98-95-3 Nitrobenzene
79-46-9 Nitropropane, 2-
55-18-5 NiNitrosodiethylamine
924-16-3 N-Nitrosodi-n-butylamine
930-55-2 N-Nitrosoyrrolidine
95-50-1 o-Dichlorobenzene
95-53-4 o-Toluidine
106-46-7 p-Dichlorobenzene
108-95-2 Phenol
85-44-9 Phthalic anhydride
75-56-9 Propylene oxide
110-86-1 Pyridine
100-42-5 Stryene
1746-01-6 TCDD-2,3,7,8- .
630-20-6 Tetrachloroethane, 1,1,1,2-
79-34-5 Tetrachloroethane, 1,1,2,2-
127-18-4 Tetrachloroethylene
108-88-3 Toluene
10061-02-6 trans-1,3-Dichloropropylene
75-25-2 Tribromomethane
76-13-1 Freon 113 (Trichloro-1,2,2- 1,1,2- trifluoroethane)
120-82-1 Trichlorobenzene, 1,2,4- .
71-55-6 Trichloroethane, 1,1,1-
79-00-5 Trichloroethane, 1,1,2-
79-01-6 Trichloroethylene
75-69-4 Trichlorofluoromethane
121-44-8 Triethylamine
108-05-4 Vinyl acetate
75-01-4 Vinyl chloride
1330-20-7 Xylenes
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Protecting Air Quality—Protecting Air Quality
developed by 1SCST3 for many separate sce-
narios designed to cover a broad range of
unit characteristics, including:
• 60 meteorological stations, chosen to
represent the 9 general climate
regions of the continental U.S.
• 4 unit types.
• 17 surface area sizes for landfills,
land application units and surface
impoundments, and 11 surface area
sizes and 7 heights for waste piles.
• 6 receptor distances from the unit
(25, 50, 75, 150, 500, 1000 meters).
• 16 directions in relation to the edge
of the unit.
The -default dispersion factors were derived
by modeling many scenarios with various
combinations of parameters, then choosing as
the default the maximum dispersion factor
for each waste management unit/surface
area/meteorological station/receptor distance
combination.
Based on the size and location of a unit, as
specified by a user, IWAIR selects an appro-
priate dispersion factor from the default dis-
persion factors in the model. If the user
specifies a unit surface area that falls between
two of the sizes already modeled, a linear
interpolation method will estimate dispersion
in relation to the two closest unit sizes.
Alternatively, a user can enter a site-specif-
ic dispersion factor developed by conducting
independent modeling with ISCST3 or with a
different model and proceed to the next step,
the risk calculation.
3.
Risk Model
The third component to the model com-
bines the constituents air concentration with
receptor exposure factors-and toxicity bench-
marks to calculate either the risk from con-
centrations managed in the unit or the waste
concentration (Cw) in the unit that should
not be exceeded to protect human health. In
calculating either estimate, the model applies
default values for exposure factors, including
inhalation rate, body weight, exposure dura-
tion, and exposure frequency. These default
values are based on data presented in the
Exposure Factors Handbook (U.S. EPA, 1995a)
and represent average exposure conditions.
IWAIR maintains standard healdi benchmarks
(CSFs for carcinogens and RfCs for noncar-
cinogens) for 95 constituents. These health
benchmarks are from the Integrated Risk
Information System (IRIS) and the Health
Effects Assessment Summary Tables (HEAST).
IWAIR uses these data to perform either a for-
ward calculation to obtain risk estimates or a
backward calculation to obtain protective
waste concentration estimates.
4.
Estimation Process
Figure 5 provides an overview of the step-
wise approach the user follows to calculate
risk or protective waste concentration esti-
mates with IWAIR. The seven steps of the
estimation process are shown down the right
side of the figure, and the user specified
inputs are listed to the left of each step. As
the user provides input data, the program
proceeds to the next step. Each step of the
estimation process is discussed below.
a. Select Calculation Method. The user
selects one of two calculation meth-
ods. Use the forward calculation to
arrive at chemical-specific and cumu-
lative risk estimates if the user knows
the concentrations of constituents in
the waste. Use the backward calcula-
tion method to estimate protective
waste concentrations not to be
exceeded in new units. The screen
where this step is performed is shown
in Figure 6.
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Protecting Air Quality—Protecting Air Quality
Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations:
This figure shows the steps in the tool to assist the user in developing risk or
protective waste concentration estimates.
U>arfip*a !((*•:
WMU htertttfcm fo a
pxmmsfcus
ti»«r Specif is*;
*
»
L «
5-24
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Protecting Air Quality—Protecting Air Quality
Figure 6. Screen 1, Method, Met Station, WMU.
•
tttff ^ttfltf £*&!«»*
'-. THaaf
v.-.^-
"*>v
*&?
Figure 7. Screen 2, Wastes Managed.
>»*»«-i»
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Protecting Air Quality—Protecting Air Quality
b. Identify Waste Management Unit.
Four WMU types can be modeled:
surface impoundments (Sis), land
application units (LAUs), active land-
fills (LFs), and wastepiles (WPs). For
each WMU, you will be asked to
specify some design and operating
parameters such as surface.area,
depth for surface impoundments and
landfills, height for wastepiles, and
tilling depth for LAUs. The amount
of unit specific data needed as input
will vary depending on whether the
user elects to develop CHEMDAT8
emission rates. IWAIR provides
default values for several of the oper-
ating parameters that the user can
choose, if appropriate.
c. Define Waste Managed. Specify
constituents and concentrations in
the waste if you choose a forward
calculation to arrive at chemical spe-
cific risk estimates. If you choose a
backward calculation to estimate pro-
tective waste concentrations, then
specify constituents of concern. The
screen where this step is performed
is shown in Figure 7.
d. Determine Emission Rates. You can
elect to develop CHEMDAT8 emis-
sion rates or provide your own site-
specific emission rates for use in
calculations. IWAIR will also ask for
facility location information to link
the facility's location to one of the 60
IWAIR meteorological stations. Data
from the meteorological stations pro-
vide wind speed and temperature
information needed to develop emis-
sion estimates. In some circum-
stances the user might already have •
emissions information from monitor-
ing or a previous modeling exercise.
As an alternative to using the CHEM-
DAT8 rates, a user can provide their
own site-specific emission rates
developed with a different model or
based on emission measurements.
e. Determine Dispersion. The user can
provide site-specific unitized disper-
sion factors (ug/m3 per ug/m2-s) or
have the model develop dispersion
factors based on user-specified WMU
information and the IWAIR default
dispersion data. Because a number of
assumptions were made in develop-
ing the IWAIR default dispersion
data you can elect to provide site-
specific dispersion factors which can
be developed by conducting inde-
pendent modeling with ISCST3 or
with a different model. Whether you
use IWAIR or provide dispersion fac-
tors from another source, specify dis-
tance to the receptor from the edge
of the WMU and the receptor type
(i.e., resident or worker). These data
are used to define points of exposure.
f. Calculate Ambient Air
Concentration. For each receptor,
the model combines emission rates
and dispersion data to estimate ambi-
ent air concentrations for all waste
constituents of concern.
Calculate Results. The model calcu-
lates results by combining estimated
ambient air concentrations at a speci-
fied exposure point with receptor
exposure factors and toxicity bench-
marks. Presentation of results
depends on whether you chose a for-
ward or backward calculation:
Forward calculation: Results are estimates of
cancer and non-cancer risks from inhalation
exposure to volatilized constituents in the
waste. If risks are too high, options are: 1)
implement unit controls to reduce volatile air
emissions, 2) implement pollution preven-
g.
5-26
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Protecting Air Quality—Protecting Air Quality
tion or treatment to reduce volatile organic
compound (VOC) concentrations before the
waste enters the unit, or 3) conduct a full
site-specific risk assessment to more precisely
characterize risks from the unit.
Backward calculation: Results are estimates of
constituent concentrations in waste that can be
protectively managed in the unit so as not to
exceed a defined risk level (e.g., 1 x 10'6 or
hazard quotient of 1) for specified receptors. A
target risk level for your site can be calculated
based on a number of site-specific factors
including, proximity to potential receptors,
waste characteristics, and waste management
practices. This information should be used to-
determine preferred characteristics for wastes
entering the unit. There are several options if it
appears that planned waste concentrations
might be too high: 1) implement pollution
prevention or treatment to reduce VOC con-
centrations in the waste, 2) modify waste man-
agement practices to better control VOCs (for
example, use closed tanks rather than surface
impoundments), or 3) conduct a full site-spe-
cific risk assessment to more precisely cfeaara'c-
terize risks from the unit.
5. Capabilities and Limitations of
the Model
In many cases, IWAIR will provide a rea-
sonable alternative to conducting a full-scale
site-specific risk analysis to determine if a
WMU poses unaceeptabfe risk to human
health. Because the model can accommodate
only a limited amount of site-specific infor-
mation, however, it is important to under-
stand its capabilities and recognize situations
when it might not be appropriate to use.
Capabilities
• The model provides a reasonable rep-
resentation of VOC inhalation risks
associated with waste management
units.
The model is easy-to-use and
requires a minimal amount of data
and expertise.
The model is flexible and provides
features to meet a variety of user
needs.
A user can enter emission and/or dis-
persion factors derived from another
model (perhaps to avoid some of the
limitations below) and still use
IWAIR to conduct a risk evaluation.
The model can run a forward calcula-
tion from the unit or a backward cal-
culation from the receptor point.
A user can modify health bench-
marks (HBNs) and target risk level,
when appropriate and in consultation
with other stakeholders.
liimitatrans
Release Mechanisms and Exposure
Routes. The model considers expo-
sures from breathing ambient air. It
does not address potential risks
attributable to particulate releases nor
does it address risks associated with
indirect routes' of exposure (i.e, non-
inhalation routes of exposure).
Additionally, in the absence of user-
specified emission rates, volatile
emission estimates are developed
with CHEMDAT8 based on unit- and
waste-specific data. The CHEMDAT8
model was developed to address only
volatile emissions from waste man-
agement units. Competing mecha-
nisms that can generate additional
exposures to the constituents in the
waste such as runoff, erosion, and
5-27
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Protecting Air Quality—Protecting Air Quality
particulate emissions are not
accounted for in the model.
Waste Management Practices. The
user specifies a number of unit-spe-
cific parameters that significantly
impact the inhalation pathway (e.g.,
size, type, and location of WMU,
which is important in identifying
meteorological conditions). However,
the model cannot accommodate
information concerning control tech-
nologies such as covers that might
influence the degree of volatilization
(e.g., whether a wastepile is covered
immediately after application of new
waste). In this case, it might be advis-
able to generate site-specific emission
rates and enter those into IWAIR.
Terrain and Meteorological
Conditions. If a facility is located in
an area of intermediate or complex
terrain or with unusual meteorologi-
cal conditions, it might be advisable
to either 1) generate site-specific air
dispersion modeling results for the
site and enter those results into the
program, or 2) use a site-specific risk
modeling approach different from
IWAIR. The model will inform the
user which of the 60 meteorological
stations is used for a facility. If the
local meteorological conditions are
very different from the site chosen by
the model, it would be more accurate
to choose a different model.
The terrain type surrounding a facili-
ty can impact air dispersion model-
ing results and ultimately risk
estimates. In performing air disper-
sion modeling to develop the IWAIR
default dispersion factors, the model
ISCST3 assumes the area around the
WMU is of simple or flat terrain. The
Guideline on Air Quality Models (U.S.
EPA, 1993) can assist users in deter-
mining whether a facility is in an
area of simple, intermediate, or com-
plex terrain.
• Receptor Type and Location.
IWAIR has predetermined adult
worker and resident receptors, six
receptor locations, and predeter-
mined exposure factors. The program
cannot be used to characterize risk
for other possible exposure scenarios.
For example, the model can not eval-
uate receptors that are closer to the
unit than 25 meters or those that are
further from the unit than 1,000
meters. If the population of concern
for your facility is located beyond the
limits used in IWAIR, consider using
a model that is more appropriate for
the risks posed from your facility.
C. Site-specific Risk
Analysis
IWAIR is not the only model that can be
applicable to a site. In some cases, a site-spe-
cific risk assessment might be more advanta-
geous. A site-specific approach can be
tailored to accommodate the individual needs
of a particular WMU. Such an approach
would rely on site-specific data and on the
application of existing fate and transport
models. Table 6 summarizes available emis-
sions and/or dispersion models that can be
applied in a site-specific analysis. Practical
considerations include the source of the
model(s), the ease in obtaining the model(s),
and the nature of the model(s) (i.e., is it pro-
prietary), and the availability of site-specific
data required for use of the model. Finally,
the model selection process should determine
whether or not the model has been verified
against analytical solutions, other models,
and/or field data. Proper models can be
selected based on the physical and chemical
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Protecting Air Quality—Protecting Air Quality
Model Ntoie
Table 6
Source Characterization Models
: Summary
AP-42
The EPA's Compilation of Air Pollutant Emission Factors, Volume I: Stationary
Point and Area Sources (AP-42), is a compilation of emission factors for a wide
variety of air emission sources, including fugitive dust sources (Section 13.2).
Emission factors are included for paved roads, unpaved roads, heavy construc-
tion operations, aggregate handling and storage piles, industrial wind erosion
(this is the 1988 Cowherd model), and abrasive blasting. These are simple emis-
sion factors or equations that relate emissions to inputs (e.g., silt loading or con-
tent, moisture content, mean vehicle weight, area, activity level, and wind
speed). Guidance is provided for most inputs, but the more site-specific the
input data used, the more accurate the results.
The entire AP-42 documentation is available at , hotline at
919.541-5610 for more information.
Cowherd
The Cowherd model, Rapid Assessment of Exposure to Paniculate Emissions
from Surface Contamination. Sites, allows the user to calculate paniculate emis-
sion rates for wind erosieni nsoig data on wind speed and various parameters
that describe the surface being eroded. The latest (1988) version of this model is
event-based (i.e., eHasfair is modeled as occurring in response to specific events
n which the wtaispEBi exceeds-fads needed to cause wind erosion). An older
p985i))veTsiQm0Ctnemwdeii5 not event-based (i.e., erosion is modeled as a
bug-term average;, w.itiHrout regard! to specific wind speed patterns over time).
TBe older version is less complicated and requires fewer inputs, but produces
more conservative results (i.e., higher emissions). The documentation on both
models provides guidance on developing all inputs. Both require data on wind
speed (fastest mile for the 1988 version and annual average for the 1985 ver-
sion), anemometer height, roughness height, and threshold friction velocity. The
.985 version also requires input on vegetative cover. The 1988 version requires
data on number of disturbances per year and, if the source is not a flat surface,
3ile shape and orientation to the fastest mile.
he 1985 version of the model is presented in. Rapid Assessment of Exposures to
Paniculate Emissions from Surface Contamination Sites (U.S. EPA, 1985). Office
if Health and Environmental Assessment, Washington DC.
The 1988 version of the model is available as part of AP-42, Section 13.2.5 (see
bove).
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Protecting Air Quality—Protecting Air Quality
; Model Name
ISCLT3
Table 6
Source Characterization Models
Summary
The Industrial Source Complex Model-Long Term, ISCLT3, is a steady state
Gaussian plume dispersion model that can be used to model dispersion of con-
tinuous emissions from point or area sources over transport distances of less
than 50km. It can estimate air concentration for vapors and particles, and dry
deposition rates for particles (but not vapors), and can produce these outputs
averaged over seasonal, annual, or longer time frames. ISCLT3 inputs include
readily available meteorological data known as STAR (STability ARray) sum-
maries (these are joint frequency distributions of wind speed class by wind
direction sector and stability class, and are available from the National Climate
Data Center in Asheville, North Carolina), and information on source character-
istics (such as height, area, emission rate), receptor locations, and a variety of
modeling options (such as rural or urban). Limitations of ISCLT3 include inabili-
ty to model wet deposition, deposition of vapors, complex terrain, or shorter
averaging times than seasonal, all of which can be modeled by ISCST3. In addi-
tion, the area source algorithm used in ISCLT3 is less accurate than the one used
in ISCST3. The runtime for area sources, however, is significantly shorter for
ISCLT3 than for ISCST3.
ISCLT3 is available at .
ISCST3
A steady-state Gaussian plume dispersion model that can estimate concentration,
dry deposition rates (particles only), and wet deposition rates. Is applicable for
continuous emissions, industrial source complexes, rural or urban areas, simple
or complex terrain, transport distances ofless than 50 km, and averaging times
from hourly to annual.
Available at .
Landfill Air Emissions Estimation
Model (LAEEM)
Used to estimate emission rates for methane, carbon dioxide, nonmethane
volatile organic compounds, and other hazardous air pollutants from municipal
solid waste landfills. The mathematical model is based on a first order decay
equation that can be run using site-specific data supplied by the user for the
parameters needed to estimate emissions or, if data are not available, using
default value sets included in the model.
Developed by the Clean Air Technology Center (CATC). Can be used to estimate
emission rates for methane, carbon dioxide, nonmethane organic compounds,
and individual air pollutants from landfills. Can also be used by landfill owners
and operators to determine if a landfill is subject to the control requirements of
the federal New Source Performance Standard (NSPS) for new municipal solid
waste (MSW) landfills (40 CFR 60 Subpan WWW) or the emission guidelines
for existing MSW landfills (40 CFR 60 Subpart CC).
Developed for municipal solid waste landfills; might not be appropriate for all
industrial waste management units.
Available at .
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Protecting Air Quality—Protecting Air Qualify
Table 6
Source Characterization Models
Model Name'
;5unimar y;,
Wastewater Treatment Compound
Property Processor and Air Emissions
Estimator Program (WATER9)
WATER9 is a Windows based computer program and consists of analytical
expressions for estimating air emissions of individual waste constituents in
wastewater collection, storage, treatment, and disposal facilities; a database list-
ing many of the organic compounds; and procedures for obtaining reports of
constituent fates, including air emissions and treatment effectiveness.
WATER9 is a significant upgrade of features previously obtained in the computer
programs WATERS, Chem9, and ChemdatS. WATER9 contains a set of model
units that can be used together in a project to provide a model for an entire facil-
ity. WATER9 is able to evaluate a full facility that contains multiple wastewater
inlet streams, multiple collection systems, and complex treatment configurations.
It also provides separate emission estimates for each individual compound that is
identified as a constituent of the wastes.
WATER9 has the ability to use site-specific compound property information, and
the ability to estimate missing compound property values. Estimates of the total air
emissions from the wastes are obtained by summing the estimates for the individ-
ual compounds. The EPA document Air Emissions Models for Waste and'Wastcwater
(U.S. EPA, 1994a) includes the equations used in the WATER9 model.
Available at .
Contact the Air Emissions Model Hotline at 919 541-5610 for support or more
informaliorr.
Toxic Modeling System Short Term
(TOXST)
An interactive PC-based system'to analyze intermittent emissions from toxic
sources. Estimates the dispersion of toxic air pollutants from point, area, and
volume sources at a complex industrial site. This.system uses a Monte Carlo sim-
ulation to allow the estimation of ambient concentration impacts for single and
multiple pollutants from continuous and intermittent sources. In addition, the
model estimates the average annual frequency with which user-specified concen-
tration thresholds are expected to be exceeded at receptor sites around the mod-
eled facility. TOXST requires the use of ISCT3 model input files for physical
source parameters.
Available at .
Toxic Screening Model (TSCREEN)
TSCREEN, a Model for Screening Toxic Air Pollutant Concentrations, should be
used in conjunction with the "Workbook of Screening Techniques for Assessing
Impacts of Toxic Air Pollutants." The air toxics dispersion screening models
imbedded in TSCREEN that are used for the various scenarios are SCREEN2,
RVD, PUFE. and the Britter-McQuaid model. Using TSCREEN, a particular
release scenacicais'sele-cted via input parameters, and TSCREEN model to simu-
late that scenario''.. Tfe rrroifel to be used and the worst case meteorological con-
ditions are aut'ematfeally, selected; tesed on criteria given in the workbook.
TSCREEN has* a; frawtendi control* program to the models that also provides, by
use of interactive menusarR£dte8 entry screen-, the same steps as the workbook.
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Protecting Air Quality—Protecting Air Quality
attributes of the site in question. As with all •
modeling, however, you should consult with
your state prior to investing significant
resources in a site-specific analysis. The state
might have preferred models or might be able
to help plan the analysis.
III. Emission Control
Techniques
A. Controlling Particulate
Matter
Particulate matter (PM) consists of air-
borne solid and liquid particles. PM is easily
inhaled and can cause various health prob-
lems. PM also impacts the environment by
decreasing visibility and harming plants as
well as transporting constituents off site.
Constituents can. sorb to particulate matter
and, therefore, wind blown dust is a potential
pathway for constituents to leave the site. It is
recommended that facilities adopt controls to
address emissions of airborne particulates.
Solid PM that becomes airborne directly or
indirectly as a result of human activity, is
referred to as fugitive dust16 and it can be
generated from a number of different sources.
The most common sources of fugitive dust at
waste management units include vehicular
traffic on unpaved roads and land-based
units, wind erosion from land-based units,
and waste handling procedures. Developing a
fugitive dust control plan is an efficient way
to tackle these problems. The plan should
include a description of all operations con-
ducted at the unit, a map, a list of all fugitive
dust sources at the unit, and a description of
the control measures that will be used to
minimize fugitive dust emissions. OSHA has
established standards for occupational expo-
sure to dust (see 29 CFR § 1910.1000). You
should check to see if your state also has reg-
ulations or guidance concerning dust or fugi-
tive emission control.
PM emissions at waste management units
vary with the physical and chemical charac-
teristics of waste streams; the volume of waste
handled; the size of the unit, its location, and
associated climate; and waste transportation
and placement practices. The subsections
below discuss the main PM-generating opera-
tions and identify emission control tech-
niques. The waste management units of main
concern for PM emissions include landfills,
waste piles, land application units, and closed
surface impoundments.
1. Vehicular Operations
Waste and cover material are often trans-
ported to units using trucks. If the waste has
the potential for PM to escape to the atmos-
phere during transport, you should cover the
waste with tarps or place wastes in containers
such as double bags or drams.17
A unit can also use vehicles to construct
lifts in landfills, apply liquids to land applica-
tion units, or dredge surface impoundments.
Consider using "dedicated" equipment—vehi-
cles that operate only within the unit and are
not routinely removed from the unit to per-
form other activities. This practice reduces
the likelihood that equipment movement will
spread contaminated PM outside the unit. To
control PM emissions when equipment must
be removed from the landfill unit, such as for
maintenance, a wash station can remove any
contaminated material from the equipment
before it leaves the unit. You should ensure
that this is done in a curbed wash area where
wash water is captured and properly handled.
To minimize PM emissions from all vehi-
cles, it is recommended that you construct
temporary roadways with gravel or other
5-32
16 Fugitive emissions are defined as emissions not caught by a capture system and therefore exclude PM
emitted from exhaust stacks with control devices.
17 Containerizing wastes provides highly effective control of PM emissions, but, due to the large volume of
many industrial waste streams, containerizing waste might not always be feasible.
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Protecting Air Quality—Protecting Air Quality
coarse aggregate material to reduce silt con-
tent and thus, dust generation. In addition,
consider regularly cleaning paved roads and
other travel surfaces of dust, mud, and conta-
, minated material.
In land application units, the entire appli-
cation surface is often covered with a soil-
waste mix. The most critical preventive
control measure, therefore, involves minimiz-
ing contact between the application surface
and waste delivery vehicles. If possible, allow
only dedicated application vehicles on the
surface, restricting delivery vehicles to a stag-
ing or loading area where they deposit waste
into application vehicles or holding tanks. If
delivery vehicles must enter the application
area, ensure that mud and waste are not
tracked, out and deposited on roadways,
where they can dry and then be dispersed by
wind or passing vehicles.
2. Waste Placement and
Handling
PM emissions from waste placement and
handling activities are less likely if exposed
material has a high moisture content.
Therefore, consider wetting the waste prior to1
loadout. Increasing the moisture content,
however, might not be suitable for all waste
streams and can result in- an unacceptable
increase in leachate production. To reduce
the need for water or suppressants, cover or
confine freshly exposed material. In addition,
consider increasing the moisture content of
the cover material.
It can also be useful to apply water to unit
surfaces; after waste placement. Water is gen-
erally applied using a truck with a gravity or
pressure feed. Watering might or might not
be advisable depending on application inten-
sity and frequency, the potential for tracking
of contaminated material off site, and climac-
tic conditions. PM control efficiency generally
increases with application intensity and fre-
quency but also depends on activity levels,
climate, and initial surface conditions.
Infrequent or low-intensity water application
typically will not provide effective control,
while too frequent or high-intensity applica-
tion can increase leachate volume, which can
strain leachate collection systems and threat-
en ground water and surface water. Addition
of excess water to bulk waste material or to
limit surfaces also can reduce the structural
fetegritf af the landfill lifts, increase tracking
e€ conKamrinated mud off site, and increase
odor. These undesirable possibilities can have
long-term implications for the proper man-
agement of a unit. Before instituting a water-
ing program, therefore, ensure that addition
of water does not produce undesirable
impacts on ground- and surface-water quality.
You should consult with your state agency
with respect to these problems.
Chemical tfast suppressants are an alterna-
tive to water application. The suppressants are
detergent-like surfactants that increase the
total number of droplets and allow particles to
more easily penetrate the droplets, increasing
the total surface area and contact potential.
Adding a surfactant to a relatively small quan-
tity of water and mixing vigorously produces
small-bubble, high-energy foam in the 100 to
200 um size range. The foam occupies very
little liquid volume, and when applied to the
surface of the bulk material, wets the fines
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Protecting Air Quality—Protecting Air Quality
Table 7. Example List of Chemical Suppressants*
Product
Manufacturer
Bitumens
Salts
Adhesives
AMS 2200, 2300®
Coherex®
Docal 1002®
Peneprime®
PetroTacP® '
Resinex®
Retain®
Calcium chloride
Dowflake, Liquid Dow®
DP-10®
Dust Ban 8806®
Dustgard®
Sodium silicate
Acrylic DLR-MS®
Bio Cat 300-1®
CPB-12®
Curasol AK®
DCL-40A, 1801, 1803®
DC-859, 875®
Dust Ban®
Flambinder®
Lignosite®
Norlig A, 12®
Orzan Series®
Soil Card®
Arco Mine Sciences
Witco Chemical
Douglas Oil Company
Utah Emulsions
Syntech Products Corporation
Neyra Industries, Inc.
Dubois Chemical Company
Allied Chemical Corporation
Dow Chemical
Wen-Don Corporation
Nalco Chemical Company
G.S.L. Minerals and Chemical Corporation
The PQ Corporation
Rohm and Haas Company
Applied Natural Systems, Inc.
Wen-Don Corporation
American Hoechst Corporation
Calgon Corporation
Betz Laboratories, Inc.
Nalco Chemical Company .
Flambeau Paper Company
Georgia Pacific Corporation
Reed Lignin, Inc.
Crown Zellerbach Corporation
Walsh Chemical
Mention of trade names or commercial products is not intended to constitute endorsement or recom-
mendation for use.
Source: U.S. EPA, 1989.
more effectively than water. When applied to
a unit, suppressants cement loose material
into a more impervious surface or form a sur-
face which attracts and retains moisture.
Examples of chemical dust suppressants are
provided in Table 7. The degree of control
achieved is a function of the application
intensity and frequency and the dilution ratio.
Chemical dust suppressants tend to require
less frequent application than water, reducing
the potential for leachate generation. Their
efficiency varies, depending on the same fac-
tors as water application, as well as spray
nozzle parameters, but generally falls
between 60 and 90 percent reduction in fugi-
tive dust emissions. Suppressant costs, how-
ever, can be high.
At land application units, if wastes contain
considerable moisture, PM can be suppressed
through application of more waste rather
than water or chemical suppressants. This
method, however, is only viable if it would
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Protecting Air Quality—Protecting Air Qualify
not cause an exceedence of a design waste
application rate or exceed the capacity of soil
and plants to assimilate waste.
At surface impoundments, the liquid
nature of the waste means PM is not a major
concern while the unit is operational. Inactive
or closed surface impoundments, however,
can emit PM during scraping or bulldozing
operations to remove residual materials. The
uppermost layer of the low permeability'soils,
such as compacted clay, which can be used to
line a surface impoundment, contains the
highest contaminant concentrations.
Particulate emissions from this uppermost
layer, therefore, are the chief contributor to
contaminant emissions. When, removing
residuals from active units, you should ensure
that equipment scrapes only the residuals,
avoiding the liner below.
3.
Wind Erosion
Wind erosion occurs when a dry surface is
exposed to the atmosphere. The effect is most
pronounced with bare surfaces of small parti-
cles, such as silty soil; heavier or better
anchored material, such as stones or clumps
of vegetation, has limited erosion potential
and requires higher wind speeds before ero-
sion can begin.
Compacted clay and ih-situ soil liners tend
to form crusts as their surfaces dry Crusted,
surfaces usually have little or no erosion
potential. Examine the crusit thickness and
strength during site inspections If the crust
does not crumble easily the erosion potential
might be minimal.
Wind fences or barriers are effective means
by which to control fugitive dust emissions
from open dust sources. The wind'fence or
barrier reduces wind velocity and turbulence
in an area whose length is many times the
height of the fence. This allows settling of
large particles and reduces emissions from
the exposed surface. It can also shelter mate-
rials handling operations to reduce entrain-
ment during load-in and loadout. Wind
fences or barriers can be portable and either
man-made structures or vegetative barriers,
such as trees. A number of studies have
attempted to determine the effectiveness of
wind fences or barriers for the control of
windblown dust under field conditions.
Several of these studies have shown a
decrease in wind velocity, however, the
degree of emissions reduction varies signifi-
cantly from study to study depending on test
conditions.
Other wind erosion control measures
include passive enclosures such as three-
sided bunkers for the storage of bulk materi-
als, storage silos for various types of aggregate
material, and open-ended buildings. Such
enclosures are most easily used with small,
temporary waste piles. At land application
units that use spray application, further wind
erosion control can be achieved simply by
not spraying waste on windy days.
Windblown PM emissions from a waste
pile depend on how frequently the pile is dis-
turbed, the moisture content of the waste, the
proportion of aggregate fines, and the height
of the pile. When small-particle wastes are
loaded onto a waste pile, the potential for
dhast emissions is at a maximum, as small
pmieles are easily disaggregated and'picked
up Bj wind. This tends to occur when mater-
ial is eitfer added to or removed from the
pile or when the pile is otherwise reshaped.
On the other hand, when the waste remains
undisturbed for long periods and is weath-
ered, its potential for dust emissions can be
greatly reduced. This occurs when moisture
from precipitation and condensation causes
aggregation and cementation of fine panicles
to the surface of larger particles, and when
vegetation grows on the pile, shielding the
surface and strengthening it with roots.
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Protecting Air Quality—Protecting Air Quality
Finally, limiting the height of the pile can
reduce PM emissions, as wind velocities gen-
erally increase with distance from the
ground.
B. VOC Emission Control
Techniques
If air modeling indicates that VOC emis-
sions are a concern, you should consider pol-
lution prevention and treatment options to
reduce risk. There are several control tech-
niques you can use. Some are applied before
the waste is placed in the unit, reducing
emissions; others contain emissions that
occur after waste placement; still others
process the captured emissions.
7. Choosing a Site to Minimize
Airborne Emission Problems
Careful site choice can reduce VOC emis-
sions. Locations that are sheltered from wind
by trees or other natural features are prefer-
able. Knowing the direction of prevailing
winds and determining whether the unit
would be upwind from existing and expected
future residences, businesses, or other popu-
lation centers can result in better siting of
units. After a unit is sited, observe wind
direction during waste placement, and plan
or move work areas accordingly to reduce
airborne emission impacts on neighbors.
2. Pretreatment of Waste
Pretreating waste can remove organic com-
pounds and possibly eliminate the need for
further air emission controls. Organic
removal or pretreatment is feasible for a vari-
ety of wastes. These processes, which include
steam or air stripping, thin-film evaporation,
solvent extraction, and distillation, can some-
times remove essentially all of the highly
volatile compounds from your waste.
Removal of the volatiles near the point of
generation can obviate the need for controls
on your subsequent process units and can
facilitate recycling the recovered organics
back to the process.
The control efficiency of organic removal
depends on many factors, such as emissions
from the removal system, and the uncon-
trolled emissions from management units
before the removal device was installed.
Generally, overall organic removal efficiencies
of 98 to over 99 percent can be achieved.
3. Enclosure of Units
You might be able to control VOC emis-
sions from your landfill or waste pile by
installing a flexible membrane cover, enclos-
ing the unit in a rigid structure, or using an
air-supported structure. Fans maintain posi-
tive pressure to inflate an air-supported struc-
ture. Some of the air-supported covers that
have been used consist of PVC-coated poly-
ester with a polyvinyl fluoride film backing.
The efficiency of air-supported structures
depends primarily on how well the structure
prevents leaks and how quickly any leaks
that do occur are detected. For effective con-
trol, the air vented from the structure should
be sent to a control device, such as a carbon
adsorber. Worker safety issues related to
access to the interior of any flexible mem-
brane cover or other pollutant concentration
system should also be considered.
Wind fences or barriers can also aid in
reducing organic emissions by reducing air
mixing on the leeward side of the screen. In
addition, wind fences reduce soil moisture
loss due to wind, which can in turn result in
decreased VOC emissions.
Floating membrane covers, provide control
on various types of surface impoundments,
including water reservoirs in the western
United States. For successful control of
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Protecting Air Quality—Protecting Air Quality
organic compounds, the membrane must
provide a seal at the edge of the impound-
ment and rainwater must be removed. If gas
is generated under the cover, vents and a
control device might also be needed.
Emission control depends primarily on the
type of membrane, its thickness, and the
nature of the organic compounds in the
waste. Again, we recommend that you con-
sult with your state or local air quality agency
to identify the most appropriate emission
control for your impoundment.
4. Treatment of Captured VOCs
In some cases, waste will still emit some
VOCs despite waste reduction or pretreat-
ment efforts. Enclosing the unit serves to pre-
vent the immediate escape of these VOCs to
the atmosphere. To avoid eventually releasing
VOCs through an enclosures ventilation sys-
tem, a treatment system is necessary Some of
the better-known treatment methods are dis-
cussed below; others also are be available.
a. Adsorption
Adsorption is the adherence of particles of
one substance, in this case VOCs, to the sur-
face of another substance, in this case a filtra-
tion or treatment matrix. The matrix can be
replaced or flushed when its surface becomes
saturated with the collected VOCs.
Carbon Adsorption. In carbon adsorp-
tion, organics are selectively collected on the
surface of a porous solid. Activated carbon is
a common adsorbent because of its high
internal surface area: 1 gram of carbon can
have a surface area equal to that of a football
field and can typically adsorb up to half its
weight in organics. For adsorption to be
effective, replace, regenerate, or recharge the
carbon when treatment efficiency begins to
decline. In addition, any emissions from the
disposal or regeneration of the carbon should
be controlled. Control efficiencies of 97 to 99
percent have been demonstrated for carbon
adsorbers in many applications.
Biofiltration. While covering odorous
materials with soil is a longstanding odor
control practice, the commercial use of biofil-
tration is a relatively recent development.
Biofilters reproduce and improve upon the
soil cover concept used in landfills. In a
biofilter, gas emissions containing biodegrad-
able VOCs pass through a bed packed with
damp, porous organic particles. The biologi-
cally active filter bed then adsorbs the VOCs.
Microorganisms attached to the wetted filter
material aerobically degrade the adsorbed
chemical compounds. Biofiltration can be a
highly effective and low-cost alternative to
other, more conventional, air pollution con-
trol technologies such as thermal oxidation,
catalytic incineration, condensation, carbon
adsorption, and absorption. Successful com-
mercial biofilter applications include treat-
ment of gas emissions from composting
operations, rendering plants, food and tobac-
co processing, chemical manufacturing,
foundries, and other industrial facilities.18
b. Condensation
Condensers work by cooling the vented
vapors to their dew point and removing the
organics as liquids. The efficiency of a con-
denser is determined by the vapor phase con-
centration of the specific organics and the
condenser temperature. Two common types
of condensers are contact condensers and
surface condensers.
c Absorption
In absorption, the organics in the vent gas
dissolve in a liquid. The contact between the
absorbing liquid and the vent gas is accom-
plished in spray towers,, scrubbers, or packed
or plate columns. Some common solvents
that might be useful for volatile organics
'Mycock,J.C.,J.D. MCKenna, andL. Theodore. 1995. Handbook of Air Pollution Control Engineering
and Technology
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Protecting Air Quality—Protecting Air Quality
include water, mineral oils, or other non-
volatile petroleum oils. Absorption efficien-
cies of 60 to 96 percent have been reported
for organics. The material removed from the
absorber can present a disposal or separation
problem. For example, organics must be
removed from the water or nonvolatile oil
without losing them as emissions during the
solvent recovery or treatment process.
d. Vapor Combustion
Vapor combustion is another control tech-
nique for vented vapors. The destruction of
organics can be accomplished in flares; ther-
mal oxidizers, such as incinerators, boilers,
or process heaters; and in catalytic oxidizers.
Flares are an open combustion process in
which oxygen is supplied by the air sur-
rounding the flame. Flares are either operated
at ground level or elevated. Properly operated
flares can achieve destruction efficiencies of
at least 98 percent. Thermal vapor incinera-
tors can also achieve destruction efficiencies
of at least 98 percent with adequately high
temperature, good mixing, sufficient oxygen,
and an adequate residence time. Catalytic
incinerators provide oxidation at tempera-
tures lower than those required by thermal
incinerators. Design considerations are
important because the catalyst can be
adversely affected by high temperatures, high
concentrations of organics, fouling from par-
ticulate matter or polymers, and deactivation
by halogens or certain metals.
5. Special Considerations for
Land Application Units
Since spraying wastes increases contact
between waste and air and promotes VOC
emissions, if the waste contains volatile
organics you might want to choose another
application method, such as subsurface injec-
tion. During subsurface injection, waste is
supplied to the injection unit directly from a
remote holding tank and injected approxi-
mately 6 inches into the soil; hence, the
waste is not exposed to the atmosphere. In
addition, you should consider pretreating the
waste to remove the organics before placing
it in the land application unit.
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Protecting Air Quality—Protecting Air Quality
Protecting Air Activity List
We recommend that you consider the following issues when evaluating and controlling air
emissions from industrial waste "management units:
D Understand air pollution laws and regulations, and determine whether and how they
apply to a unit.
D Evaluate waste management units to identify possible sources of volatile organic
emissions.
D Work with your state agency to evaluate and implement appropriate emission control
techniques, as necessary.
5-39
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Protecting Air Quality—Protecting Air Quality
Resources
American Conference of Governmental Industrial Hy'gienists. 1997. Threshold Limit Values for Chemical
Substances and Physical Agents and Biological Exposure Indices.
Christensen, T.H., R. Cossu, and R. Stegmann. 1995. Siting, Lining Drainage & Landfill Mechanics,
Proceeding from Sardinia 95 Fifth International Landfill Symposium, Volume II.
Finn, L., and R. Spencer. 1987. Managing Biofilters for Consistent Odor and VOC Treatment. BioCycle.
January.
Hazardous Waste Treatment, Storage and. Disposal Facilities and Hazardous Waste Generators; Organic Air
Emission Standards for Tanks, Surface Impoundments, and Containers; Final Rule. Federal Register. Volume
59, Number 233, December 6, 1994. pp. 62896 - 62953.
Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineering and
Technology.
National Ambient Air Quality Standards for Particulate Matter. Federal Register. Volume 62, Number 138, July
18, 1997. pp. 38651-38701.
Orlemann, J.A., TJ. Kalman, J.A. Cummings, E.Y. Lin. 1983. Fugitive Dust Control Technology.
Robinson, W 1986. The Solid Waste Handbook: A Practical Guide.
Texas Center for Policy Studies. 1995. Texas Environmental Almanac, Chapter 6, Air Quality,
U.S. EPA. 2002a. Industrial Waste Air Model Technical Background Document. EPA530-R-02-010.
U.S. EPA. 2002b. Industrial Waste Air Model (IWAIR) User's Guide. EPA530-R-02-011.
U.S. EPA. 1998. Taking Toxics out of the Air: Progress in Setting "Maximum Achievable Control Technology"
Standards Under the Clean Air Act. EPA451-K-98-001.
U.S. EPA. 1997a. Best Management Practices (BMPs) for Soil Treatment Technologies: Suggested Operational
Guidelines to Prevent Cross-Media Transfer of Contaminants During Clean-Up Activities. EPA530-R-97-007.
U.S. EPA. 1997b. Residual Risk Report to Congress. EPA453-R-97-001.
U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. Third
Edition.
5-40
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Protecting Air Quality—Protecting Air Quality
Resources (cont.)
U.S. EPA. 1995a. Exposure Factors Handbook: Volumes 1-3. EPA600-P-95-002FA-C.
U.S. EPA. 1995b. Survey of Control Technologies for Low Concentration Organic Vapor Gas Streams.
EPA456-R-95-003.
U.S. EPA. 1995c. User's Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume I.
EPA454-B-95-003a.
U.S. EPA. 1995d. User's Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume II-
Description of Model Algorithms. EPA454-B-95-003b.
U.S. EPA. 1994a. Air Emissions Models for Waste and Wastewater. EPA453-R-94-080A.
U.S. EPA. 1994b. Handbook: Control Techniques for Fugitive VOC Emissions from Chemical Process
Facilities. EPA625-R-93-005.
U.S. EPA. 1994c. Toxic Modeling System Short-Term (TOXST) User's Guide: Volume I. EPA454-R-94-058A.
U.S. EPA. 1993. Guideline on Air Quality Models. EPA450-2-78-027R-C
U.S. EPA. 1992a. Control of Air Emissions from Superfund Sites. EPA625-R-92-012.
U.S. EPA. 1992b. Protocol for Determining the Best Performing Model. EPA454-R-92-025.
U.S. EPA. 1992c. Seminar Publication: Organic Air Emissions from Waste Management Facilities. EPA625-
R-92-003.
U.S. EPA. 1991. Control Technologies for Hazardous Air Pollutants. EPA625-6-91-014.
U.S. EPA. 1989. Hazardous Waste TSDF—Fugitive Particulate Matter Air Emissions Guidance Document.
EPA450-3-89-019.
U.S. EPA. 1988. Compilation of Air Pollution Emission Factors. AP-42.
U.S. EPA. 1985. Rapid Assessment of Exposures to Particulate Emissions form Surface Contamination
Sites.
Viessman, W, and M. Hammer. 1985. Water Supply and Pollution Control.
5-41
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-------
Part III
Protecting Surface Water
Chapter 6
Protecting Surface Water
-------
-------
Contents
I. Determining the Quality and Health of Surface Waters 6 - 1
A. Water Quality Criteria 6 - 2
B. Water Quality Standards 6 _ 2
C. Total Maximum Daily Load (TMDL) Program 5 - 3
II. Surface-Water Protection Programs Applicable to Waste Management Units 6 - 4
A. National Pollutant Discharge Elimination System (NPDES) Permit Program 6 - 4
1. Storm-Water Discharges : ..6 - 5
2. Discharges to Surface Waters 6 _ 5
B. National Pretreatment Program 6 _ g
1. Description of the National Pretreatment Program g - 6
2. Treatment of Waste at POTW Plants -..; : g - 8
III. Understanding Fate and Transport of Pollutants g - 10
A. How Do Pollutants Move From Waste Management Units To Surface Water? 6 - 10
1. Overland Flow g _ IQ
2. Ground Water to Surface Water g - 11
3. Air to Surface Water g _ 11
B. What Happens When Pollutants Enter Surface Water? g - 12
C. Pollutants Of Concern 6 . 13
IV Protecting Surface Waters g - 13
A. Controls to Address Surface-Water Contamination from Overland Flow g - 13
1. Baseline BMPs g _ IQ
2. Activity-Specific BMPs g - 18
3. Site-Specific BMPs : .,; g _ 19
B. Controls to Address Surface-water Contamination from Ground Water to Surface Water 6 - 29
C. Controls to Address Surface-water Contamination from Air to Surface Water 6 - 29
V Methods of Calculating Run-on and Runoff Rates g - 30
Protecting Surface Water Activity List 6 - 33
Resources... 6-34
Figures:
Figure 1. BMP Identification and Selection Flow Chart 6 - 17
Figure 2. Coverings 6 - 22
Figure 3. Silt Fence 6 - 24
-------
Contents (cont.)
Figure 4. Straw Bale •
Figure 5. Storm Drain Inlet Protection
Figure 6. Collection and Sedimentation Basin • 6 " 26
Figure 7. Outlet Protection
x: -po
Figure 8. Infiltration Trench
Figure 9. Typical Intensity-Duration-Frequency Curves 6 " 31
Tables:
Table 1. Biological and Chemical Processes Occurring in Surface Water Bodies 6 - 14
Table 2. Priority Pollutants 6 " 15
-------
Protecting Surface Water—Protecting Surface Water
Protecting Surface Water
This chapter will help you:
• Protect surface waters by limiting the discharge of pollutants into
the waters of the United States.
• Guard against inappropriate discharges of pollutants associated
with process wastewaters and storm water to ensure the safety of
the nation's surface waters.
• Reduce storm-water discharges by complying with applicable regula-
tions, implementing available storm-water controls, and identifying
best management practices (BMPs) to control storm water.
Over 70 percent of the Earth's
surface is water. Of all the
Earth's water, 97 percent is
found in the oceans and seas,
while 3 percent is fresh water.
This fresh water is found in glaciers, lakes,
ground water, wetlands, and rivers. Because
This chapter will help you address the
following questions. "»• ""'
• What surface-water protection pro-
grams are applicable to my waste
management unit? "
w
* What are the objectives "of run-on and
runoff control systems? -,.
• What should be considered in design-
ing surface-water protection systems' *
• What BMPs should be implemented
to protect surface waters from pollu-
tants associated with waste manage-
ment units?. « ,
• What are some of the engineering and
physical mechanisms available to con-
trol storm water?
water is such a valuable commodity, the pro-
tection of our surface waters should be every-
one's goal. Pollutants1 associated with waste
management units and storm-water dis-
charges must be controlled.
This chapter summarizes how EPA and
states determine the quality of surface waters
and subsequently describes the existing sur-
face-water protection programs for ensuring
the health and integrity of waterbodies. The
fate and transport of pollutants in the surface-
water environment is also discussed. Finally,
various methods that are used to control pollu-
tant discharges to surface waters are described.
I. Determining the
Quality and
Health of
Surface Waters
The protection of aquatic resources is gov-
erned by the Clean Water Act (CWA). The
objective of the CWA is to "restore and main-
tain the chemical, physical, and biological
1 To be consistent with the terminology used in the Clean Water Act, the term pollutant is used in this
chapter in place of the term constituent. In this chapter, pollutant means an effluent or condition intro-
duced to surface waters that results in degradation. Water pollutants include human and animal wastes,
nutrients, soil and sediments, toxics, sewage, garbage, chemical wastes, and heat.
6-1
-------
Protecting Surface Water—Protecting Surface Water
What is water quality?
Water quality reflects the composition of
water as affected by natural causes and
human activities, expressed in terms of
measurable quantities and related to
intended water use. Water quality is deter-^-
mined by comparing physical, chemical,
biological, microbiological, and radiologi-
cal quantities and parameters to a set of
standards and criteria. Water quality is
perceived differently by different people
For example, a public health official rmghtr
be concerned widi the bacterial and viral
safety of water used for drinking and
bathing, while fishermen might be con-
cerned that the quality of water be suffi-
cient to provide the best habitat for fish.
For each intended use and water quality
benefit; different parameters can be used
to express water quality
integrity of the nation's waters" (Section
101(a)). Section 304(a) of the CWA authorizes
EPA to publish recommended water quality
criteria that provide guidance for states to use
in adopting water quality standards under
Section 303(c). Section 303 of the CWA also
establishes the Total Maximum Daily Load
(TMDL) Program which requires EPA and the
states to identify waters not meeting water
quality standards and to establish TMDLs for
those waters.
A. Water Quality Criteria
Under authority of Section 304 of the
CWA, EPA publishes water quality "criteria"
that reflect available scientific information on
the maximum acceptable concentration levels
of specific chemicals in water that will protect
aquatic life, human health, and drinking
water. EPA has also established nutrient crite-
ria (e.g., phosphorus and nitrogen) and bio-
logical criteria (i.e., biointegrity values). These
criteria are used by the states for developing
enforceable water quality standards and iden-
tifying problem areas.
Water quality criteria are developed from
toxicity studies conducted on different organ-
isms and from studies of the effects of toxic
compounds on humans. Federal water quality
criteria specify the maximum exposure con-
centrations that will provide protection of
aquatic life and human health. Generally,
however, the water quality criteria describe
the quality of water that will support a partic-
ular use of the waterlsady. For the protection
of aquatic life a two-value5sterion has been
established to account for acute
toxicity of pollutants. The human health crite-
rion specifies the risk incurred with exposure
to the toxic compounds at a specified concen-
tration. The human health criterion is associ-
ated with the increased risk of contracting a
debilitating disease, such as cancer.
B. Water Quality Standards
Water quality standards are laws or regula-
tions that states (and authorized tribes) adopt
to enhance and maintain the quality of water
and protect public health. States have the pri-
mary responsibility for developing and imple-
menting these standards. Water quality
standards consist of three elements: 1) the
"designated beneficial use" or "uses" of a
waterbody or segment of a waterbody 2) the
water quality "criteria" necessary to protect
the uses of that particular waterbody, and 3)
an antidegradation policy. "Designated use" is
a term that is specified in water quality stan-
dards for a body of water or a segment of a
body of water (e.g., a particular branch of a
river). Typical uses include public water sup-
ply, propagation of fish and wildlife, and
recreational, agricultural, industrial, and navi-
gational purposes. Each state develops its own
use classification system based on the generic
6-2
-------
Protecting Surface Water—Protecting Surface Water
^ U.S,-B?A Selectepl WaterlQuality Criteria
Chemical
Benzene "
Cadmium,
DDT
PCBs
> Aquatic life/
> Freshwater 'At ,
X. ^ *^
Acute Chronic
" ,5300 x ^
•*_±r ±_1; *'*^^
,11 s. 0.001
A2- ' '0.014, ;"
Manne
Acute
5100 ^
i.'43/.
"0.13 *
.- 10
» i, 4 /
-o- /
Chronic
700 „
94 1 "
0.001
0;03,x
in Micrograms per Liter
, Human Health io
Water and Fish
Ingestion
' o'ee' "Js <
10
0.000024'
^"0.000079
6*Risk
Fish Ingestion
Only
40
> 5- J
0.000024
0 000079
uses cited in the CWA. The states may differ-
entiate and subcategorize the types of uses
that are to be protected, such as cold-water or
warm-water fisheries, or specific species that
are to be protected (e.g., trout, salmon, bass).
States may also designate special uses to pro-
tect sensitive or valuable aquatic life or habi-
tat. In addition, the water quality criteria
adopted into a state water quality standard
may or may not be the same number pub-
lished by EPA under section 304. States have
the discretion to adjust the EPA's criteria to
reflect local environmental conditions and
human exposure patterns.
The CWA requires that the states review
their standards at least once every three years
and submit the results to EPA for review. EPA
is required to either approve or disapprove
the standards, depending on whether they
meet the requirements of the CWA. When
EPA disapproves a standard, and the state
does not revise the standard to meet EPA's
objection, the CWA requires the Agency to
propose substitute federal standards.
C. Total Maximum Daily
Load (TMDL) Program
Lasting solutions to water quality problems
and pollution control can be best achieved by
looking at the fate of all pollutants in a water-
shed. The CWA requires EPA to administer
the total maximum daily load (TMDL) pro-
gram, under which the states establish the
allowable pollutant loadings for impaired
waterbodies (i.e., waterbodies not meeting
state water quality standards) based on their
"waste assimilative capacity" EPA must
approve or disapprove TMDLs established by
the states. If EPA disapproves a state TMDL,
EPA must establish a federal TMDL.
A TMDL is a calculation of the maximum
amount of a pollutant that a waterbody can
receive and still meet water quality standards.
The calculation must include a margin of
safety to ensure that the waterbody can be
used for the purposes the state has designat-
ed. The calculation must also account for sea-
sonal variation in water quality.
The quantity of pollutants that can be dis-
charged into a surface-water body without
use impairment (also taking into account nat-
ural inputs such as erosion) is known as the
"assimilative capacity." The assimilative capac-
ity is the range of concentrations of a sub-
stance or a mixture of substances that will
not impair attainment of water quality stan-
dards. Typically, the assimilative capacity of
surface-water bodies might be higher for
biodegradable organic matter, but it can be
very low for some toxic chemicals that accu-
mulative in the tissues of aquatic organisms
and become injurious to animals and people
using them as food.
-------
Protecting Surface Water—Protecting Surface Water
What is a watershed?
Watersheds are areas of land that dram to
surface-waterbodies. A watershed general-
ly includes lakes, rivers, estuaries, wet-
lands, streams, and the surrounding "
landscape. Ground-water recharge areas
are also considered part of a watershed.
Because watersheds are defined by natur-
al hydrology, they represent the most log-
ical basis for managing surface-water x
resources. Managing die watershed as a
whole allows state and local authorities to
gain a more complete understanding of
overall conditions in an/area and the
cumulative stressors which affect the sur- ^
face-water body. Information on. EPA's w'
strategy to protect and restore water qual-
ity and aquatic ecosystems at the water-,
shed level can be found at -cwww.epa.
gov/owow/watershed/index2.html>,
II. Surface-Water
Protection
Programs
Applicable to
Waste
Management
Units
To ensure that a state's water quality stan-
dards and TMDLs are being met, discharges of
pollutants are regulated through the National
Pollutant Discharge Elimination System
(NPDES) Permit Program and the National
Pretreatment Program. These permitting pro-
grams are implemented and enforced at the
state or local level.
A. National Pollutant
Discharge Elimination
System (NPDES) Permit
Program
The CWA requires most "point sources"
(i.e., entities that discharge pollutants of any
kind into waters of the United States) to have
a permit establishing pollution limits, and
specifying monitoring and reporting require-
ments. This permitting process is known as
the National Pollutant Discharge Elimination
System (NPDES). Permits are issued for three
types of wastes that are collected in sewers
and treated at municipal wastewater treat-
ment plants or that discharge directly into
receiving waters: process wastewater, non-
process wastewater, and storm water. Most
discharges of municipal and industrial storm
water require NPDES permits, but some
other storm water discharges do not require
permits. To protect public health and aquatic
life and assure that every facility treats waste-
water, NPDES permits include the following
terms and conditions.
• Site-specific effluent (or discharge)
limitations.
• Standard and site-specific compliance
monitoring and reporting require-
ments.
• Monitoring, reporting, and compliance
schedules that must be met.
There are various methods used to monitor
NPDES permit conditions. The permit will
require the facility to sample its discharges and
notify EPA and- the state regulatory agency of
these results. In addition, the permit will
require the facility to notify EPA and the state
regulatory agency when the facility determines
it is not in compliance with the requirements
of a permit. EPA and state regulatory agencies
also send inspectors to facilities in order to
6-4
-------
Protecting Surface Water—Protecting Surface Water
determine if they are in compliance with the
conditions imposed under their permits.
NPDES permits typically establish specific
"effluent limitations" relating to the type of
discharge. For process wastewaters, the per-
mit incorporates the more stringent of tech-
nology-based limitations (either at 40 CFR
Parts 405 through 471 or developed on a
case-by-case basis according to the permit
writer's best professional judgement) or water
quality-based effluent limits (WQBELs).
Some waste management units, such as sur-
face impoundments, might have an NPDES
permit to discharge wastewaters directly to
surface waters. Other units might need an
NPDES permit for storm-water discharges.
NPDES permits are issued by EPA or states
with NPDES permitting authority. If you are
located in a state with NPDES authority, you
should contact the state directly to determine
the requirements for your discharges. EPA's
Office of Wastewater Management's Web page
contains a complete, updated list of the states
with approved NPDES permit programs, as
well as a fact sheet and frequently asked
questions about the NPDES permit program
at . If a state does not
have NPDES permitting authority, you should
follow any state requirements for discharges
and contact EPA to determine the applicable
federal requirements for discharges.
7. Storm-Water Discharges
EPA has defined 11 categories of "storm-
water discharges associated with industrial
activity" that require a permit to discharge to
navigable waters (40 CFR Part 122.26 (b)
(14)). These 11 categories are: 1) facilities
subject, to storm-water effluent limitations
guidelines, new source performance stan-
dards (NSPS), or toxic pollutant effluent stan-
dards under 40 CFR Part 129 (specifies
manufacturers of 6 specific pesticides), 2)
When is*an NPDES permit
needed?
•*-•>, ^^
To answer questions about whether or
not a facility needs to seek NPDES per-
mit coverage/orcto determine whether a
particular program is administered by
EPA or a state'agency, contact your state
or EPA regional storm-water office.
Currently, 44 states and the U.S. Virgin
Islands have federally-approved state
NPDES'permit programs. The following
6 states do, not have final EPA approval:
Alaska, Arizona, Idaho, Massachusetts,
New Hampshire, and New Mexico.
(As of March 2001)
"heavy" manufacturing facilities, 3) mining
and oil and gas operations with "contaminat-
ed" storm-water discharges, 4) hazardous
waste treatment, storage, or disposal facilities,
5) landfills, land application sites, and open
dumps, 6) recycling facilities, 7) steam elec-
tric generating facilities, 8) transportation
facilities, 9) sewage treatment plants, 10)
construction operations disturbing five or
more acres, and 11) other industrial facilities
where materials are exposed to storm water.
Nonhazardous waste landfills, waste piles,
and. land application units are included in
category 5.. Under a new Section 122.26(b)
(15), storm water discharges from construc-
taxDu operations disturbing between one and
five acres wilt be required to obtain a NPDES
permit effective in March 2003. There will
be, however, some waivers from, permit
requirements availaHe.
To provide flexibility for the regulated
community in acquiring NPDES storm-water
discharge permits, EPA has two NPDES per-
mit application options: individual permits
and general permits.2 Applications for indi-
Initially, a group application option was available for facilities with similar activities to jointly submit a
single application for permit coverage. A multi-sector general permit was then issued based upon infor-
mation provided in the group applications. The group application option was only used during the ini-
tial stages of the program and is no longer available.
6-5
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Protecting Surface Water—Protecting Surface Water
What types of pollutants
are regulated by NPDES?
Conventional pollutants are contained
in the sanitary wastes of households,
businesses, and industries. These pollu-
tants include human wastes, ground-up
food from sink disposals, and laundry
and bath waters. Conventional pollutants
include fecal coliform, oil and grease,
total suspended solids (TSS), biochemical
oxygen demand (BOD), and pH.
Toxic pollutants are particularly harm-
ful to animal or plant life. They are pri-
marily grouped into organics (including'
pesticides, solvents, polychlorinated
biphenyls (PCBs), and dioxins) and metals
(including lead, silver, mercury, copper,
chromium, zinc, nickel, and cadmium).
Nonconventional pollutants are any
additional substances that are not con-
sidered conventional or toxic that may
require regulation. These include nutri-
ents such as nitrogen and phosphorus.
vidual permits require the submission of a
site drainage map, a narrative description of
the site that identifies potential pollutant
sources, and quantitative testing data for spe-
cific parameters. General permits usually
involve the submission of a Notice of Intent
(NOI) that includes only general information,
which is neither industry-specific or pollu-
tant-specific and typically do not require the
collection of monitoring data. NPDES general
storm-water permits typically require the
development and implementation of storm-
water pollution prevention plans and BMPs
to limit pollutants in storm-water discharges.
The EPA has also issued the Multi-Sector
General Permit (60 FR 50803; September 29,
1995) which covers 29 different industry sec-
tors. The Agency reviewed, on a sector-by-
sector basis, information concerning industri-
al activities, BMPs, materials stored outdoors,
and end-of-pipe storm-water sampling data.
Based on this review, EPA identified pollu-
tants of concern in each industry sector, the
sources of these pollutants, and the BMPs
used to control them. The Multi-Sector
General Permit requires the submission of an
NOI, as well as development and implemen-
tation of a site-specific pollution prevention
plan, as the basic storm-water control strategy
for each industry sector. :
2. Discharges to Surface Waters
Most surface impoundments that are
addressed by the Guide are part of a facility's
wastewater treatment process that results in
an NPDES-permitted discharge to surface
waters. The NPDES permit only sets pollu-
tion limits for the final discharge of treated
wastewater. Generally, the NPDES permit
would not establish any regulatory require-
ments regarding the design or operation of
the surface impoundments that are part of
the treatment process except that, once
designed and constructed, a provision
requires use of those treatment processes
except in limited circumstances. Individual
state environmental agencies, under their
own statutory authorities, can impose
requirements on surface impoundment
design and operation.
B.
7.
National Pretreatment
Program
Description of the National
Pretreatment Program
For industrial facilities that discharge
wastewaters to publicly owned treatment
works (POTW) through domestic sewer lines,
pretreatment of the wastewater may be
required (40 CFR Part 403). Under the
6-6
-------
Protecting Surface Water—Protecting Surface Water
National Pretreatment Prpgram, EPA, states,
and local regulatory agencies establish dis-
charge limits to reduce the level of pollutants
discharged by industry into municipal sewer
systems. These limits control the pollutant
levels reaching a POTW improve the quality
of the effluent and sludges produced by the
POTW, and increase the opportunity for ben-
eficial use of the end products (e.g., effluents,
sludges, etc). Further information about
industrial pretreatment and the National
Pretreatment Program is available on the
Office of Wastewater Managements Web page
at .
POTWs are designed to treat domestic
wastes and biodegradable commercial and
industrial wastes. The CWA and EPA define
the pollutants from these sources as "conven-
tional pollutants" which includes those spe-
cific pollutants that are expected to be
present in domestic discharges to POTWs.
Commercial and industrial facilities can,,
however, discharge toxic pollutants that a
treatment plant is neither designed nor able
to remove. Such discharges, from both indus-
trial and commercial sources, can cause seri-
ous problems at POTWs. The undesirable
outcome of these discharges can be prevented
by using treatment techniques or manage-
ment practices to reduce'or eliminate the dis-
charge of these pollutants.
The act of treating wastewafier gadarar &a> dis-
charge tff a POTW is ccmmoiiff referred to as
"pretreatment." The National Pretreatment
Program provides the statutory and regulatory
basis to require non-domestic dischargers to
comply with pretreatment standards to ensure
that the goals of the CWA are attained. The
objectives of the National Pretreatment
Program are to:
• Prevent the introduction of pollutants
into POTWs which will interfere with
the operation of a POTW, including
interference with the disposal of
municipal sludge.
• Prevent the introduction of pollutants
into POTWs which will pass through
the treatment works or otherwise be
incompatible with such works.
• Improve opportunities to recycle and
reclaim municipal and industrial
wastewaters and sludges.
To help accomplish these objectives, the
National Pretreatment Program is charged
with controlling 126 priority pollutants from
industries that discharge into sewer systems
as described in the CWA, Section 307(a), and
listed in 40 CFR Part 423 Appendix A. These
priority pollutants fall into two categories,
metals and toxic organics.
• The metals include lead, mercury,
chromium, and cadmium. Such toxic
metals cannot be destroyed or broken
down through treatment or environ-
mental degradation. They can cause
various human health problems such
as lead poisoning and cancer.
• The toxic organics include solvents,
pesticides, dioxins, and polychlorinat-
ed biphenyls (PCBs). These can be
cancer-causing and lead to other seri-
ous ailments, such as kidney and liver
damage, anemia, and heart failure.
The objectives of the National
Ftetfrea&mentt Program are achieved by apply-
ing and enfolding three types of discharge
standards: I) prohibited discharge standards
(provide for overall protection of POTWs), 2)
categorical standards applicable to specific
point source categories (provide for general
protection of POTWs), and 3) local limits
(address the water quality and other concerns
at specific POTWs).
Prohibited Discharge Standards. All
industrials users (Ills), whether or not subject
to any other federal, state, or local pretreat-
-------
Protecting Surface Water—Protecting Surface Water
ment requirements, are subject to the general
and specific prohibitions identified in 40 CFR
Part 403.5 (a) and (b), respectively. General
prohibitions forbid the discharge of any pol-
lutant to a POTW that can pass through or
cause interference. Specific prohibitions for-
bid the discharge of pollutants that pose fire
or explosion hazards; corrosives; solid or vis-
cous pollutants in amounts that will obstruct
system flows; quantities of pollutants that will
interfere with POTW operations; heat that
inhibits biological activity; specific oils; pollu-
tants that can cause die release of toxic gases;
and pollutants diat are hauled to the POTW
(except as authorized by the POTW).
Categorical Standards. Categorical pre-
treatment standards are national, uniform,
technology-based standards that apply to dis-
charges to POTWs from specific industrial
categories (e.g., battery manufacturing, coil
coating, grain mills, metal finishing, petrole-
um refining, rubber manufacturing) and limit
the discharge of specific pollutants. These
standards are described in 40 CFR Parts 405
through 471.
Categorical pretreatment standards can be
concentration-based or mass-based.
Concentration- based standards are expressed
as milligrams of pollutant allowed per liter of
wastewater discharged (mg/1) and are issued
where production rates for the particular
industrial category do not necessarily corre-
late with pollutant discharges. Mass-based
standards are generally expressed as a mass
per unit of production (e.g., milligrams of
pollutant per kilogram of product produced)
and are issued where production rates do
correlate with pollutant discharges. Thus,
limiting the amount of water discharge (i.e.,
water conservation) is important to reducing
the pollutant load to the POTW For a few
categories where reducing a facility's flow vol-
ume does not provide a significant difference
in the pollutant load discharged, EPA has
established both mass- and concentration-
based standards. Generally, both a daily maxi-
mum limitation and a long-term average
limitation (e.g., average daily values in a cal-
endar month) are established for each regu-
lated pollutant.
Local Limits. Federal regulations located
at 40 CFR Parts 403.8 (f) (4) and 122.21 (j)
(4) require authorities to evaluate die need
for local limits and, if necessary, implement
and enforce specific limits protective of that
POTW. Local limits might be developed for
pollutants such as metals, cyanide, BOD, TSS,
oil & grease, and organics that can interfere
with or pass through the treatment works,
cause sludge contamination, or cause worker
health and safety problems if discharged at
excess levels.
All POTWs designed to accommodate
flows of more than 5 million gallons per day
and smaller POTWs with significant industri-
al discharges are required to establish pre-
treatment programs. The EPA Regions and
states with approved pretreatment programs
serve as approval authorities for the National
Pretreatment Program. In that capacity, they
review and approve requests for POTW pre-
treatment program approval or modification,
oversee POTW program implementation,
review requested modifications to categorical
pretreatment standards, provide technical
guidance to POTWs and Ills, and initiate
enforcement actions against noncompliant
POTWs and TUs.
2. Treatment of Waste at POTW
Plants
A waste treatment works' basic function is
to speed up the natural processes by which
water is purified and returned to receiving
lakes and streams. There are two basic stages
in the treatment of wastes, primary and sec-
ondary. In the primary stage,, solids are
6-8
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Protecting Surface Water—Protecting Surface Water
allowed to settle and are removed from
wastewater. The secondary stage uses biologi-
cal processes to further purify wastewater.
Sometimes, these stages are combined into
one operation. POTWs can also perform
other "advanced treatment" operations to
remove ammonia, phosphorus, pathogens
and other pollutants in order to meet effluent
discharge requirements.
Primary treatment. As sewage enters a
plant for treatment, it flows through a screen,
which removes large floating objects such as
rags and sticks that can clog pipes or damage
equipment. After sewage has been screened, it
passes into a grit chamber, where cinders,
sand, and small stones settle to the bottom. At
this point, the sewage still contains organic
and inorganic matter along with other sus-
pended solids. These solids are minute parti-
cles that can be removed from sewage by
treatment in a sedimentation tank. When the
speed of the flow of sewage through one of
these tanks is reduced, the suspended solids
will gradually sink to the bottom, where they
form a mass of solids caEed raw primary
sludge. Sludge is usually removed from tanks
by pumping, after which it can be further
treated for use as fertilizer, or disposed of
through incineration if necessary. To complete .
primary treatment, effluent from the sedimen-
tation tank is usually disinfected with chlorine
before being discharged into receiving waters.
Sometimes chlorine is fed into the water to
kill pathogenic bacteria and to reduce
unpleasant odors.
Secondary treatment. The secondary stage
of treatment removes about 85 percent of the
organic matter in sewage by making use of the
bacteria in it. The two principal techniques
used in secondary treatment are trickling fil-
ters and the activated sludge process.
Trickling filters. A trickling filter is a bed of
stones from three to six feet deep through
which the sewage passes. More recently, inter-
locking pieces of corrugated plastic or other
synthetic media have also been used in trick-
ling beds. Bacteria gather and multiply on
these stones until they can consume most of
the organic matter in the sewage. The cleaner
water trickles out through pipes for further
treatment. From a trickling filter, the sewage
flows to another sedimentation tank to
remove excess bacteria. Disinfection of the
effluent with chlorine is generally used to
complete the secondary stage. Ultraviolet
light or ozone are also sometimes used in sit-
uations where residual chlorine would be
harmful to fish and other aquatic life.
Activated sludge. The activated sludge treat-
ment process speeds up the work of the bac-
teria by bringing air and sludge, heavily laden
with bacteria, into close contact with sewage.
After the sewage leaves the settling tank in
the primary stage, it is pumped into an aera-
tion tank, where it is mixed with air and
sludge loaded with bacteria and allowed to
remain for several hours. During this time,
ttEte bacteria break down the organic matter
infc» fanjmiess by-products. The sludge, now
activated wish additional millions of bacteria
and other tiny organisms, can be used again
by returning it to the aeration tank for mixing
with new sewage and ample amounts of air.
From the aeration tank, the sewage flows to
another sedimentation tank to remove excess
bacteria. The final step is generally the addi-
tion of chlorine to the effluent.
Advanced treatment. New pollution
problems have created additional treatment
needs on wastewater treatment'systems. Some
pollutants can be more difficult to remove
from water. Increased demands on the water
supply only aggravate the problem. These
challenges are being met through better and
more complete methods of removing pollu-
tants at treatment plants, 01 through preven-
tion of pollution at the sawze frefear to
6-9
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Protecting Surface Water—Protecting Surface Water
Chapter 3 — Integrating Pollution Prevention
for more information). Advanced waste treat-
ment techniques in use or under develop-
ment range from biological treatment capable
of removing nitrogen and phosphorus to
physical-chemical separation techniques such
as filtration, carbon adsorption, distillation,
and reverse osmosis. These wastewater treat-
ment processes, alone or in combination, can
achieve almost any degree of pollution con-
trol desired. As waste effluents are purified to
higher degrees by such treatment, the effluent
water can be used for industrial, agricultural,
or recreational purposes, or even as drinking
water supplies.
III. Understanding
Fate and
Transport of
Pollutants
A. How Do Pollutants
Move From Waste
Management Units To
Surface Water?
1. Overland Flow
The primary means by which pollutants
are transported to surface-water bodies is via
overland flow or "runoff." Runoff to surface
water is the amount of precipitation after all
"losses" have been subtracted. Losses include
infiltration into soils, interception by vegeta-
tion, depression storage and ponding, and
evapotranspiration (i.e., evaporation from the
soil and transpiration by plants).
There is a correlation between the pollu-
tant loadings to surface water and the amount
of precipitation (rainfall, snow, etc.) that falls
on the watershed in which a waste manage-
ment unit is located. In addition, the charac-
teristics of the soil at a facility also influence
pollutant loading to surface water. If, for
example, the overland flow is diminished due
to high soil infiltration, so is the transport of
particulate pollutants to surface water. Also, if
wastes are land applied and surface overland
flow is generated by a rainfall event, a signifi-
cant portion of pollutants can be moved over
land into adjacent surface water.
A diagram representing rainfall transforma-
tion into runoff and other components of the
hydrologic cycle is shown in Chapter 7:
Section A-Assessing Risk. The first stage of
runoff formation is condensation of atmos-
pheric moisture into rain droplets or ,
snowflakes. During this process, water comes
in contact with atmospheric pollutants. The
pollution content of rainwater can therefore
reach high levels. In addition, rain water dis-
What Is "runoff?"
> Runoff is water or leachate that drains
or flows over the land from any part of a
waste management unit. „ ,
% / ^'
What is''run-on?"
f
Run-on is water from outside a waste
management unit that flows into the"
unit.,Run-on includes storm water from
rainfall or the melting of snow, or ice
that falls directly on the unit, as well as"
the water that drains-from adjoining
areas. * - ~v -"« *'-.-.'
6-10
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Protecting Surface Water—Protecting Surface Water
solves atmospheric carbon dioxide and'sulfur
and nitrogen oxides, and acts as a weak acid
after it hits the ground, reacting with soil and
limestone formations. Overland flow begins
after rain particles reach the earths surface
(note that during winter months runoff for-
mation can be delayed by snowpack forma-
tion and subsequent melting). Rain hitting an
exposed waste management unit will liberate
and pick up particulates and pollutants from
the unit and can also dissolve other chemicals
it comes in contact with. Precipitation that
flows into a waste management unit, called
"run-on," can also free-up and subsequently
transport pollutants out of the unit. Runoff
carries the pollutants from the waste manage-
ment unit as it flows downgradient following
the natural contours of the watershed to
nearby lakes, rivers, or wetland areas.
2. Ground Water to Surface
Water
Ground water and surface water are funda-
mentally interconnected. In fact, it is often
difficult to separate the two because they
"feed" each other. As a result, pollutants can
move from one media to another. Shallow
water table aquifers interact closely with
streams, sometimes discharging water intota
stream or lake and sometimes receiving water
from the stream or lake. Many rivers, lakes,,
and wetlands rely heavily on ground-water
discharge as a source of water. During times
of low precipitation, some bodies of water
would not contain any water at all if it were
hot for ground-water discharge.
•An unconfined aquifer that feeds a stream
is said to provide the streams "baseflow."
Gravity is the dominant driving force in
ground-water movement in unconfined
aquifers. As such, under natural conditions,
ground water moves "downhill" until it
reaches the land surface at a spring or
through a seep in the side or bottom of a
river bed, lake, wetland, or other surface-
water body. Ground water can also leave the
aquifer via the pumping of a well. The
process of ground water outflowing into a
surface-water body or leaving the aquifer
through pumping is called discharge.
Discharge from confined aquifers occurs in
much the same way except that pressure,
rather than gravity, is the driving force in
moving ground water to the surface. When
the intersection between the aquifer and the
land's surface is natural, the pathway is called
a spring. If discharge occurs through a well,
that well is a "flowing artesian well."
3. Air to Surface Water
Pollutants released into the air are carried
by wind patterns away from their place of
origin. Depending on weather conditions and
the chemical and physical properties of the
pollutants, pollutants can be carried signifi-
cant distances from their source and can
undergo physical and chemical changes as
they travel. Some of these chemical changes
include the formation of new pollutants such
as ozone, which is formed from nitrogen
oxides £NOX) and hydrocarbons.
Atmospheric deposition occurs when pol-
lutants iir the air fall on the land or surface
waters. When pollutants are deposited in
snow, fog, or rain, the process is called wet
deposition, while the deposition of pollutants
as dry particles or gases is called dry deposi-
tion. Pollutants can be deposited into water
bodies either directly from the air onto the
surface of the water, or through indirect
deposition, where the pollutants- settle on the
land and are then carried into a water body
by runoff.
6-11
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Protecting Surface Water—Protecting Surface Water
Any pollutant that is emitted into the air
can become a surface-water problem due to
deposition. Some of the common pollutants
that can be transported to surface-water bod-
ies via air include different forms of nitrogen,
mercury, copper, polychlorinated biphenols
(PCBs), polycyclic aromatic hydrocarbons
(PAHs), chlordane, dieldrin, lead, lindane,
polycyclic organic matter (POM), dioxins,
and furans.
B. What Happens When
Pollutants Enter Surface
Water?
All pollutants entering surface water via
runoff, ground-water infiltration, or air trans-
port have an effect on the aquatic ecosystem.
Additive and synergistic effects are also fac-
tors because many different pollutants can
enter a surface-water body from diverse
sources and activities. As such, solutions to
water quality problems are best achieved by
looking at all activities and inputs to surface
water in a watershed.
Surface-water ecosystems (i.e., rivers,
lakes, wetlands, estuaries) are considered to
be in a dynamic equilibrium with their inputs
and surroundings. These ecosystems can be
divided into two components, the biotic (liv-
ing) and abiotic (nonliving). Pollutants are
continually moving between the two. For
example, pollutants can move from the abiot-
ic environment (i.e., the water column) into
aquatic organisms, such as fish. The intake of
the pollutant can occur as water moves across
the gills or directly through the skin. Toxic
pollutants can accumulate in fish (known as
bioaccumulation), as the fish uptakes more of
the pollutant than it can metabolize or
excrete. Pollutants can eventually concentrate
in an organism to a level where death results.
At that point, the pollutants will be released
The Dissolved Oxygen
Problem
The dissolved oxygen balance is an
important water quality consideration
for streams and estuaries. Dissolved oxy-
gen is the most important parameter for
protecting fish and other aquatic organ-
isms. Runoff with a high concentration
of biodegradable organics (organic mat-
ter)* can have a serious effect on the
amount of dissolved oxygen in the
water.*Low dissolved oxygen levels can
be very detrimental to fish. The content
of organic matter in waste discharges is
commonly expressed as the biochemical
, oxygen demand (BOD) load. Organic
k matter can come from a variety of
sources, including waste management
units. When runoff containing organic
matter is" introduced into receiving
waters, decomposers immediately begin
to breakdown the organic matter using
dissolved oxygenate do so. Further, if
there are numerous inputs of organic
matter into a single water body, for
example a stream^ the effects will be
additive (i.e., more and more dissolved <
oxygen will be removed from the stream
asPbrganic matter is added along the
stream reach and decomposes). This is -
" a'Iso'an example of how an input that
might not be considered a pollutant_
(i.e., organic matterXcan lead to harmful
effects due to the naturallyvoccurring
process within a surface-water body ,
back into the abiotic environment as the
organism decays. :
Pollutants can also move within the abiotic
environment, as for example, between water
and its bottom sediments. Pollutants that are
attached to soil particles being carried down-
6-12
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Protecting Surface Water——Protecting Surface Water
stream will be deposited on the bottom of the
streambed as the particles fall out of the
water column. In this manner, pollutants can
accumulate in areas of low flow. Thus, it is
obvious that the hydrodynamical, biological,
'and chemical processes in aquatic systems
cannot be separated and must be addressed
simultaneously when considering pollutant
loads and impacts to surface water. Table 1
presents some additional information on the,
biological and chemical processes that occur
in water bodies.
C Pollutants Of Concern
As you assess the different types of best
management practices (BMPs) that can be
used at waste management units to protect
surface waters (discussed in Section IV of this
chapter), you should also identify the pollu-
tants in the unit that pose the greatest threats
to surface water. Factors to consider include
the solubility of the constituents in the waste
management unit, how easily these potential
pollutants can be mobilized, degradation
rates, vapor pressures, and biochemical decay
coefficients of the pollutants and any other
factors that could encourage their release into
the environment.
While all pollutants can become toxic at
high enough levels, there are a number of
compounds that are toxic at relatively/ low
levels. These pollutants have been designated'
by the EPA as priority pollutants. The list of
priority pollutants is included in Table 2. The
list of priority pollutants is continuously
under review by EPA and is periodically
updated. The majority of pollutants on the
list are classified as organic chemicals. Others
are heavy metals which are being mobilized
into the environment by human activities at
rates greatly exceeding those of natural geo-
logical processes. Several of the priority pol-
lutants are also considered carcinogenic (i.e.,
they can increase the risk of cancer to the
human population or to aquatic organisms,
such as fish). Priority pollutants of particular
concern for surface-water bodies include:
• Metals, such as cadmium, copper,
chromium, lead, mercury, nickel, and
zinc, that arise from industrial opera-
tions, mining, transportation, and
agricultural use.
• Organic compounds, such as pesti-
cides, PCBs, solvents, petroleum
hydrocarbons, organometallic com-
pounds, phenols, formaldehyde, and
biochemical methylation of metals in
aquatic sediments.
• Dissolved gases, such as chlorine and
ammonium.
• Anions, such as cyanides, fluorides,
sulfides, and sulphates.
• Acids and alkalis.
IV. Protecting
Surface Waters
A. Controls to Address
Surface-Water
Contamination from
Overland Flow
Protecting surface water entails preventing
storm-water contamination during both the
construction of a waste management unit and
the operational life of the unit. During con-
struction the primary concern is sediment
eroding from exposed soil surfaces.
Temporary sediment and erosion control
measures, such as silt fences around con-
struction perimeters, straw bales around
storm-water inlets, and seeding or straw cov-
ering of exposed slopes, are typically used to
limit and manage erosion. States or local
6-13
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Protecting Surface Water—Protecting Surface Water
Table 1. Biological and Chemical Processes Occurring in Surface-Water Bodies
After pollutants are transported to lakes, rivers, and other water bodies, they can be subject to a
variety of biological and chemical processes that affect how'they will interact and impact the aquat-
ic ecosystem. These processes determine how pollutants are mobilized, degraded, or released into
the biotic and abiotic environments.
Metabolism of a toxicant consists of a series of chemical transformations that take place within
an organism. A wide range of enzymes act on toxicants, that can increase water solubility, and facil-
itate elimination from the organism In some cases, however, metabolites can be more toxic than
their parent compound. Sullivan 1993 Environmental Regulatory Glossary, 6th Ed Government
Institutes. -
Bioaccumulation is the uptake and sequestration of pollutants by organisms from their ambient
environment. Typically, the concentration of the substance m the organism exceeds the concentra-
tion in the environment since the organism will store the substance and not excrete it. Phillips.
1993. In: Calow (ed), Handbook of Ecotoxicology, Volume One. Blackwell Scientific Publications.
Biomagnification is the concentration of certain substances up a food^chain. It is a very impor-
tant mechanism in concentrating pesticides and heavy metals m. organisms such as fish. Certain
substances such as pesticides and heavy metals move up the food chain, work their way into a river
or lake and are eaten by large birds, other animals, or humans The substances become concentrat-
ed in tissues or internal organs as they move up the chain Sullivan 1993. Environmental Regulatory
Glossary, 6th Ed. Government Institutes
Biological degradation is the decomposition of a substance into more elementary compounds
by action of microorganisms such as bacteria Sullivan 1993 Environmental Regulatory Glossary, 6tn
Ed. Government Institutes - ^ _ "•"
Hydrolysis is a chemical process of decomposition in which the elements of water react with - -
another substance to yield one or more new substances This transformation process changes'the
chemical structure of the substance Sullivan 1993 Environmental Regulatory Glossary, 6th Ed.
Government Institutes.
Precipitation is a chemical or physical change whereby a pollutant moves from a dissolved form
in a solution to a solid or insoluble form and subsequently drops out of the solution. Precipitation
reduces the mobility of constituents, such as metals and is not generally reversible Boulding. 19,95,
Soil, Vadose Zone, and Ground-Water Contamination. Assessment, Prevention, and Remediation.
Oxidation/Reduction (Redox) process is a complex of biochemical reactions in sediment that
influences the valence state of elements (and their ions) found in sediments. Under anaerobic con-
ditions the overall process shifts to a reducing condition The chemical properties for elements can
change substantially with changes in the oxidation state. Sullivan. 1993. Environmental Reguiatory
Glossary, 6th Ed. Government Institutes. C s, „ „
Photochemical process is the chemical changes brought about by the radiant energy of the sun
acting upon various polluting substances. Sullivan. 1993. Environmental Regulatory Glossary, 6th Ed.
Government Institutes. , ,
6-14
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Protecting Surface Water—Protecting Surface Water
4 001 Acenaphthene '
002 ,Acrolem '
-003^Acrylomtnle f
*'004 Benzene' v ** „ „ *.
005 Benzidme <- / * ^'
006 Carbon tetrachlonde
007 Chlorobenzene
008 ^/htnchlorgbenzene,
009 Hexachlorbbenzene '/'
010 1,2-dichloroethane
^ Oil ;l,l>l-tnchloreothane
012 Hexachloroethanex,,/1,,
i $ / *r '
013 1,1-dichIoroethane
014, 1,1,2-trichloroethane
- 015 1,1,2,2-tetrachioroethane
, -r
• 016 Chloroethane^ ,"„
017 Bis(2-chloroethyl}*ether
'018 2-chloroethyl vinyl ethers*
019 2-chloronaphthalene
020 2,4,6-fnchlorophenol ,v
021 Parachlorometa cresoi
022 Chloroform. /
~ V ^ /
023
024
025
026
027
028
029
Table 2. Priority'-Poliutantsi
^- 043 Methylene chloride , '""•
?/^44 Methyl chloride
'045 Methyl Bromide ,,
** v>'-^f f ^ ^ f **
<,, ^ 046 Bromoform ^ f - •>
'fr^ 047 ^pichlorobromomethane" *
" 048 Chlorodibromomethanen '
049 Hexacfilorobutadiene
* ' ^ v
050 w Hejcachlorocyclopentadiene
051 'Isophorone *' *"**•* -, „
052 Naphthalene *' -
053 Nitrobenzene
^nr-S* ^^1
1,2-dichlorobenzene
1,3-dichlorobenzene
1,4-dichlorobenzene ^ '
3,3-dichlorobenzidine
1,1-dichloroethylene
1,2-trans-dichloroethylene
030 2,4-dichlorophenoL
031 1,2-dichloropropane
032 1,2-dichloropropylene
033 2,4-dimethylphenol
034. 2,4-dinitrotoluene:
035 2,6-dinitrotoluene
036 1,2-diphenylhydrazine.
037 Ethylbenzene
038 Fltioranthene
039 4-chlorophenyl pfteriyl ether
. 040 4-bromophenyl phenyl ether
041 Bis(2-chloroisopropyl) ether.
042 Bis(2-chloroethoxy) methane
055 4-nurophenol'
056 2,4-dimtrophenql
057 4,6-dtnitro-o-cresoI ^
058^ N-'mtrosodimethylamine ^
059 N-mtrosodiphenylamme
060 "N-mtrosodi-rt-propylamme
061' Pentacfclorophenol
062 Pheriol-.
063 Bis(2-et^ylhexyl) ph'thalate v
064 Butyl benzyl phthalate "\
065 Di-N-Butyl Phthalate " "'
066 Di-n-octyl phthalate
067'Diethyl Phthalate
068 Dimethyl phthalate
069 Benzo(a) anthracene "
070 Benzo(a)pyrene
, 071 Benzo(b) fluorarithene ' ,
072 Benzo(b) fluoranthene
073 Chrysene ' i ^ ^,
074 Acenaphthylene
075 Anthracene
076 Benzo(ghi) perylene
077 Fluorene
078 Phenanthrerre
0^59 Dibemzo(,h) anthracene
080 Ihdeno (1,2,3-cd) pyrene
081 Pyrene
082 Tetrachloroethylene
083 Toluene
084 Tnchloroethylene
-v- 085 Vinyl chlonde
086 Aldnn
',087^ Dieldnn ">"
'088 Chlordane -"' * ^
089^4,4-DDT
'' 090 4,4-DDE
,091 4,4-DDD '/^ v
092 Alpha-endosulfari
093 Beta-endosulfan s-
/> 094 Endosulfan sulfate
- 095 Endnn
096 Endnn aldehyde
^ 097 Heptachlor
"'098 Heptachlor epoxide
099 Alpha-BHC
" 100 Beta-BHC - '
J- lO'l ^Gamma-BHC
__ 102 Delte-BHC^ ,
"~ 103 PCB-1242
104'PCB-1254
105 PCB-122I
"106 PCB-1232
' 107 J>CB-1248
108 .PCB-1260 ' '
109 PCB-1016
110 Toxaphene ''
111 Antimoay
U2 Arsenic
113 Asbestos
,114 Beryllium
115 Cadmiumv" '
116, Chromium
•\
117 Copper
118 Cyanide, Total " '
119 Lead
120 Mercury •*
121 Nickel
^ f -*s
122 Selenium
123 Silver
124 'Thallium
125 Zinc
126 2,3,r,8-TCBD>
The list of pollutants is current as of the Federal Register dated April 2, 2001.
I5-T5
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Protecting Surface Water—Protecting Surface Water
municipalities often require the use of sedi-
ment and erosion controls at any construc-
tion site disturbing greater than a certain
number of acres, and can have additional
requirements in especially sensitive water-
sheds. You should consult with the state and
local regulatory agencies to determine the
sediment and erosion control requirements
for construction.
Once a waste management unit has been
constructed, permanent run-on and runoff
controls are necessary to protect surface
water. Run-on controls are designed to pre-
vent storm water from entering the active
areas of units. If run-on is not prevented
from entering active areas,, it can seep into
the waste and increase the amount of
leachate that must be managed. It can also
deposit pollutants from nearby sites, such as
pesticides'from adjoining farms, further bur-
dening treatment systems. Excessive run-on
can also damage earthen containment sys-
tems, such as dikes and berms. Run-on that
contacts the waste can carry pollutants into
receiving waters through overland runoff or
into ground water through infiltration. You
can divert run-on to the waste management
unit by taking advantage of natural contours
in the land or by constructing ditches or
berms designed to intercept and drain storm
water away from the unit. Run-on diversion
systems should be designed to handle the
peak discharge of a design storm event (e.g.,
a 24-hour, 25-year storm4). Also note that
surface impoundments should be designed
with sufficient freeboard and adequate capac-
ity to accommodate not only waste, but also
precipitation and run-on.
Runoff controls can channel, divert, and
convey storm water to treatment facilities or,
if appropriate, to other intended discharge
points. Runoff from landfills, land treatment
units, or waste piles should be managed as a
potentially contaminated material. The runoff
from active areas of a landfill or waste pile
should be .managed as leachate. You should
design a leachate collection and removal sys-
tem to handle the potentially contaminated
runoff, in addition to the leachate that might
be generated by the unit. You should segre-
gate noncontact runoff to reduce the volume
that will need to be treated as leachate! The
Multi-Sector General Permit does not autho-
rize discharges of leachate which includes
storm water that comes in contact with
waste. The discharge of leachate would be
regulated under either an individually drafted
NPDES permit with site- specific discharge
limitations, or an alternative NPDES general
permit if one is available. Note that for land
application sites, runoff from the site can also
adversely affect nearby surface water if pollu-
tants are picked up and carried overland.
BMPs are measures used to reduce or
eliminate pollutant releases to surface waters
via overland flow. They fall into three cate-
gories, baseline, activity-specific, and site-
specific, and can take the form of a process,
activity, or physical structure. The use of
Why are "run-on" controls necessary?
, Run-on controls are designed to pre-
vent: 1)'contamination of storm water,
2) erosion that can damage the physical
stracture'of unitsrs) surface discharge
of waste constituents,- 4) creation of -
leachate, and 5) already contaminated
surface water from entering the-unit.
What is'the purpose of a "runoff" ',"
control system?^
Runoffcontrol systems'are designed
to collect and control at a minimum the
water flow resulting from a storm event'
of a specified duration* such as a 24-
hour, 25-year .storm event. ~ -,« ''
6-16
1 This discharge is the amount of water resulting from a 24-hour rainfall event of a magnitude with a 4
percent statistical likelihood of occurring in any given year (i.e, once every 25 years). Such an event
might not occur in a given 25-year period, or might occur more than once during a single year.
-------
Protecting Surface Water—Protecting Surface Water
BMPs to protect surface water should be con-
sidered in both the design and operation of a
waste management unit. Before identifying
and implementing BMPs, you should assess
the potential sources of storm-water contami-
nation including possible erosion and sedi-
ment discharges caused by storm events. A
thorough assessment of a waste management
unit involves several steps including creating
a map of the waste management
unit area; considering the design
of the unit; identifying areas
where spills, leaks, or discharges
could or do occur; inventorying
the types of wastes contained in
the unit; and reviewing current
operating practices (refer to
Chapter 8-Operating the Waste
Management System for more
information). Figure 1 illustrates
the process of identifying and
selecting the most appropriate
BMPs.
Designing a storm-water
management system to protect
surface water involves knowl-
edge of local precipitation pat-
terns, surrounding topographic
features, and geologic condi-
tions. You should consider sam-
pling runoff to ascertain the •
quantity and concentration of
pollutants being discharged.
(Refer to the Chapter 9-
Monitoring Performance for
more information). Collecting
and evaluating this type of infor-
mation can help you to select
the most appropriate BMPs to
prevent or control pollutant dis-
charges. The same considera-
tions (e.g., types of wastes to be
contained in the unit, precipita-
tion patterns, local topography
and geology) should be made
while designing and constructing a new waste
management unit to ensure that the proper
baseline, activity-specific, and site-specific
BMPs are implemented and installed from the
start of operations. After assessing the poten-
tial and existing sources of storm-water conta-
mination, the next step is to select appropriate
BMPs to address these contamination sources.
Figure 1. BMP Identification and Selection Flow Chart
Recommended Steps
Assessment Phase
DeveJop a.site map
Inventory and describe exposed materials ;
List significant spills and leaks
Identify areas associated with industrial activity
Test for nonstorm-water discharges
Evaluate monitoring/sampling data if appropriate
(see Chapter 9-Monitoring Performance)
BMP Identification Phase
Operational BMPs
Source control BMPs
Erosion and sediment control BMPs
Treatment BMPs
Innovative BMPs
Implementation Phase
Implement BMPs
Train employees
Evaluation/Monitoring Phase
Conduct semiannual inspection/BMP evaluation (see
Chapter 8-Operating the Waste Management System)
Conduct recordkeeping
Monitor surface water if appropriate
Review and revise plan
Adapted from U.S. EPA, 1992e.
6-17
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Protecting Surface Water—Protecting Surface Water
1.
Baseline BMPs
These practices are, for the most part,
inexpensive and relatively simple. They focus
on preventing circumstances that could lead
to surface-water contamination before it can
occur. Many industrial facilities already have
these measures in place for product loss pre-
vention, accident and fire prevention, worker
health and safety, or compliance with other
regulations (refer to Chapter 8-Operating the
Waste Management System for more informa-
tion). Baseline BMPs include the measures
summarized below.
Good housekeeping. A clean and orderly
work environment is an effective first step
toward preventing contamination of run-on
and runoff. You should conduct an inventory
of all materials and store them so as to pre-
vent leaks and spills and, if appropriate,
maintain them in areas protected from pre-
cipitation and other elements.
Preventive maintenance. A maintenance
program should be in place and should
include inspection, upkeep, and repair of the
waste management unit and any measures
specifically designed to protect surface water.
Visual inspections. Inspections of sur-
face-water protection measures and waste
management unit areas should be conducted
to uncover potential problems and identify
necessary changes. Areas deserving close
attention include previous spill locations;
material storage, handling, and transfer areas;
and waste storage, treatment, and disposal
areas. Any problems such as leaks or spills
that could lead to surface-water contamina-
tion should be corrected as soon as practical.
Spill prevention and response. General
operating practices for safety and spill pre-
vention should be established to reduce acci-
dental releases that could contaminate
run-on and runoff. Spill response plans
should be developed to prevent any acciden-
tal releases from reaching surface water.
Mitigation practices. These practices con-
tain, clean-up, or recover spilled, leaked, or
loose material before it can reach surface
water and cause corltamination. Other BMPs
should be considered and implemented to
avoid releases, but procedures for mitigation
should be devised so that unit personnel can
react quickly and effectively to any releases
that do occur. Mitigation practices include
sweeping or shoveling loose waste into
appropriate areas of the unit; vacuuming or
pumping spilled materials into appropriate
treatment or handling systems; cleaning up
liquid waste or leachate using sorbents such
as sawdust; and applying gelling agents to
prevent spilled liquid from flowing towards
surface water.
, Training employees to operate, inspect,
and maintain surface-water protection mea-
sures is itself considered a BMP, as is keeping
records of installation, inspection, mainte-
nance, and performance of surface-water pro-
tection measures. For more information on
employee training and record keeping, refer
to Chapter 8-Operating the Waste
Management System.
2. Activity-Specific BMPs
After assessment and implementation of
baseline BMPs, you should also consider
planning for activity-specific BMPs. Like
baseline BMPs, they are often procedural
rather than structural or physical measures,
and they are often inexpensive and easy to
implement. In the BMP manual for industrial
facilities, Storm Water Management for
Industrial Activities: Developing Pollution
Prevention Plans and Best Management Practices
(U.S. EPA, 19920, EPA developed activity-
specific BMPs for nine industrial activities,
including waste management. The BMPs that
-------
Protecting Surface Water—Protecting Surface Water
are relevant to waste management are sum-
marized below.
Preventing waste leaks and dust emis-
sions due to vehicular travel. To prevent
leaks, you should ensure that trucks moving
waste into and around a waste management
unit have baffles (if they carry liquid waste)
or sealed gates, spill guards, or tarpaulin cov-
ers (if the waste is solid or semisolid). To
minimize tracking dust off site where it can
be picked up by storm water, wash trucks in
a curbed truck wash area where wash water
is captured and properly handled. For more
information on these topics, consult Chapter
8-Operating the Waste Management System .
You should be aware that washwater from
vehicle and equipment cleaning is considered
to be "process wastewater," and is not eligible
for discharge "under the Multi-Sector General
Permit program for industrial storm-water
discharges. Such discharges would require
coverage under either a site-specific individ-
ual NPDES permit or an NPDES general
storm-water permit.
For land application, choosing appropri-
ate slopes. You should minimize runoff by
designing a waste management unit site with
slopes less than six percent. Moderate slopes
help reduce storm-water runoff velocity
which encourages infiltration and reduces
erosion and sedimentation. Note that storm-
water discharges from land application units
are regulated under the Multi-Sector General
Permit program.
3. Site-Specific BMPs
In addition to baseline and activity-specific
BMPs, you should also consider site-specific
BMPs, which are more advanced measures
tailored to specific pollutant sources at a par-
ticular waste management unit and usually
consist of the installation of structural or
physical measures. These site-specific BMPs
can be grouped into five areas: flow diver-
sion, exposure minimization, erosion and
sedimentation prevention, infiltration, and
other prevention practices. For many of the
surface-water protection measures described
in this section, it is important to design for an
appropriate storm event (i.e., structures that
control run-on and runoff should be designed
for the discharge of a 24-hour, 25-year storm
event).
When selecting and designing surface-
water protection measures or systems, you
should consult state, regional, and local
watershed management organizations. Some
of diese organizations maintain management
plans devised at the overall watershed level
that address storm-water control. Thus, these
agencies might be able to offer guidance in
developing surface-water protection systems
for optimal coordination with other dis-
charges in the watershed. Again, after site-
specific BMPs have been installed, you should
evaluate the effectiveness of the selected
BMPs on a regular basis to ensure that they
are functioning properly.
BMP Maintenance „ < ' ""— <*» •*
1 BMPs must be maintained on a regu-,
V / r$A&; °
lar basis to ensure adequate surface- '
water protection. Maintenance is
important because st:orms can damage,
surface-water protection measures sucli
as storage basin-embankments or spill-
ways. Runoff'can also cause sediments
to settle m storage basins or ditches and
can carry floatables (i e , tree branches,
lumber, leaves, litter) to the basin. "
Facilities might need to repair storm-
water controls and periodically remove
sediment and floatables
6-19
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Protecting Surface Water—Protecting Surface Water
a. Flow Diversion
Flow diversion can be used to protect sur-
face water in two ways. First, it can channel
storm water away from waste management
units to minimize contact of storm water
with, waste. Second, it can carry polluted or
potentially polluted materials to treatment
facilities. Flow diversion mechanisms include
storm-water conveyances and diversion
dikes.
Storm-Water Conveyances (Channels, Gutters,
Drains, and Sewers)
Storm-water conveyances, such as chan-
nels, gutters, drains, and sewers, can prevent
storm-water run-on from entering a waste
management unit or runoff from leaving a
unit untreated. Some conveyances collect
storm water and route it around waste man-
agement units or other waste containment
areas to prevent contact with the waste,
which might otherwise contaminate storm
water with pollutants. Other conveyances
collect water that potentially came into con-
tact with the waste management unit and
carry it to a treatment plant (or possibly back
to the unit for reapplication in the case of
land application units, some surface
impoundments, and leachate-recirculating
landfills). Conveyances should not mix the
stream of storm water diverted around the
unit with that of water that might have con-
tacted waste. Remember, storm water that
contacts waste is considered leachate and can
only be discharged in accordance with an
NPDES permit other than the Multi-Sector
General Permit.
Storm-water conveyances can be con-
structed of or lined with materials such as
concrete, clay tile, asphalt, plastic, metal,
riprap, compacted soil, and vegetation. The
material used will vary depending on the use
of the conveyance and the expected intensity
of storm-water flow. Storm-water con-
What are some advantages of
conveyances?
Conveyances direct storm-water flows
around industrial areas, waste manage-
ment units, or other waste containment
areas to prevent temporary flooding;
require little maintenance; and provide
long-term control of storm-water flows.
What are some disadvantages of
conveyances? *
c Conveyances require routing through
stabilized structures to minimize erosion.
They also can increase flow rates, might
be impractical if there are space limita-
tions, and might not be economical.
veyances should be designed with a capacity
to accept the estimated storm-water flow
associated with the selected design storm
event. Section V of this chapter discusses
methods for determining storm water flow.
Diversion Dikes
Diversion dikes, often made with compact-
ed soil, direct run-on away from a waste man-
agement unit. Dikes are built uphill from a
unit and usually work with storm-water con-
veyances to divert storm water from the unit.
To minimize the potential for erosion, diver-
sion dikes are often constructed to redirect
runoff at a shallow slope to minimize its
velocity. A similar means of flow diversion is
grading the area around the waste manage-
ment unit to keep storm water away from the
area, instead of or in addition to using diver-
sion dikes to redirect water that would other-
wise flow into these areas. In planning for the
installation of dikes, you should consider the
slope of the drainage 'area, the height of the
dike, the size of the flow it will need to divert,
-------
Protecting Surface Water—Protecting Surface Water
and the type of conveyance that will be used
with the dike.
b. Exposure Minimization
Like flow diversion, exposure minimiza-
tion practices, such as curbing, diking, and
covering can reduce contact of storm water
with waste. They often are small structures ,
immediately covering or surrounding a high-
er risk area, while flow diversion practices
operate on the scale of an entire waste man-
agement unit.
Curbing and Diking
These are raised borders enclosing areas
where liquid spills can occur. Such areas
could include waste transfer points in land
application, truck washes, and leachate man-
agement areas at landfills and waste piles.
The raised dikes or curbs prevent spilled liq-
uids from flowing to surface waters, enabling
prompt cleanup of only a small area.
Covering
Erecting a roof, tarpaulin, or other perma-
nent or temporary covering (see Figure 2)
over the active area of a landfill or waste
transfer location can keep precipitation from
falling directly on waste materials and pre-
vent run-on from occurring. If temporary
coverings are used, you should ensure that
sufficient weight is attached to prevent wind
from moving the cover, and to repair or
replace the cover material if holes or leaks
develop.
c. . Erosion and Sedimentation
Prevention
Erosion and sedimentation practices serve to
limit erosion (the weathering of soil or rock
particles from the ground by wind, water, or
human activity) and to prevent particles that
are eroded from reaching surface waters as sed-
< What are some advantages of
diversion dikes? - * •> -
^ Diversion dikes limit storm-water
flo'ws pver industrial site areas, can be
economical1, temporary structures when
-"built from soil dnsite; and can be con-
Averted from temporary to permanent at
any'trine'*
' What are some disadvantages of
diversion dikes?
Diversion dikes are not suitable for"
< large drainage areas unless there is a
gentle'slope and might require mainte-
nance after heavy Yams
iment. Erosion and sedimentation can threaten
aquatic life, increase treatment costs for down-
stream water treatment plants, and impede
recreational and navigational uses of water-
ways. Erosion and sedimentation are of particu-
lar concern at waste management units because
the sediment can be contaminated with Waste
constituents and because erosion can undercut
or otherwise weaken waste containment struc-
tures. Practices such as vegetation, interceptor
dikes, pipe slope drains, silt fences, storm drain
inlet protection, collection and sedimentation
basins, check dams, terraces and benches, and
outlet protection can help limit erosion arid
sedimentation.
Vegetation
Erosion and sedimentation can be reduced
by ensuring that areas where storm water is
likely to flow are vegetated. Vegetation slows
erosion and sedimentation by shielding soil
surfaces from rainfall, improving the soil's
water storage capacity, holding soil in place,
slowing runoff, and filtering out sediment.
One method of providing vegetation is to pre-
serve natural growth. This is achieved by
6-21
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Protecting Surface Water—Protecting Surface Water
Figure 2. Coverings
Roof, overhang, or other
permanent structure
Tarp or other covering
From U.S. EPA, 1992e.
managing the construction of the waste man-
agement unit to minimize disturbance of sur-
rounding grass and plants. If it is not possible
to leave all areas surrounding a unit undis-
turbed, preserve strips of existing vegetation
as buffer zones in strategically chosen areas of
the site where erosion and sediment control is
most needed, such as on steep slopes uphill
of the unit and along stream banks downhill
from the unit. If it is not possible to leave suf-
ficient buffer zones of existing vegetation, you
should create buffer zones by planting such
areas with new vegetation.
Temporary or permanent seeding of erodi-
ble areas is another means of controlling ero-
sion and sedimentation using vegetation.
Permanent seeding, often of grass, is appro-
priate for establishing long-term ground
cover after construction and other land-dis-
turbing activities are complete. Temporary
seeding can help prevent erosion and sedi-
mentation in areas that are exposed but; will
not be disturbed again for a considerable
time. These areas include soil stockpiles,
temporary roadbanks, and dikes. Local regu-
lations might require temporary seeding of
areas that would otherwise remain exposed
beyond a certain period of time. You should
consult local officials to determine whether
such requirements apply. Seeding might not
be feasible for quickly establishing cover in
arid climates or during nongrowing seasons
in other climates. Sod, although more expen-
sive, can be more tolerant of these conditions
than seed and establish a denser grass cover
more quickly. Compost used in combination
with seeding can also be used effectively to
establish vegetation on slopes.
Physical and chemical stabilization, and
various methods of providing cover are also
often considered in conjunction with vegeta-
tive measures or when vegetative measures
cannot be used. Physical stabilization is
appropriate where stream flow might be
increased due to construction or other activi-
ties associated with the waste management
unit and where vegetative measures are not
practical. Stream-bank stabilization might
involve the reinforcement of stream banks
with stones, concrete or asphalt, logs, or
gabions (i.e., structures formed from crushed
rock encased in wire mesh). Methods of pro-
viding cover such as mulching, compost, mat-
ting, and netting can be used to cover ;
surfaces that are steep, arid, or otherwise
unsuitable for planting. These methods also
can work in conjunction with planting to sta-
bilize and protect seeds. (Mattings are sheets
of mulch that are more stable than loose
mulch chips. Netting is a mesh of jute, wood
fiber, plastic, paper, or cotton that can hold
mulch on the ground or stabilize soils. These
measures are sometimes used with seeding to
provide insulation, protect against birds, and
hold seeds and soil in place.) Chemical stabi-
lization (also known as chemical mulch, soil
6-22
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Protecting Surface Water—Protecting Surface Water
binder, or soil palliative) can hold the soil in
place and protect against erosion by spraying
vinyl, asphalt, or rubber onto soil surfaces.
Erosion and sediment control is immediate
upon spraying and does not depend on cli-
mate or season. Stabilizer should be applied
according to manufacturer's instructions to
ensure that water quality is not affected.
Coating large areas with thick layers of stabi-
lizer, however, can create an impervious sur-
face and speed runoff to downgradient areas
and should'be avoided.
Interceptor Dikes and Swales
Dikes (ridges of compacted soil) and
swales (excavated depressions in which storm
water flows) work together to prevent entry
of run-on into erodible areas. A dike is built
across a slope upgradient of an area to be
protected, such as a waste management unit,
with a swale just above the dike. Water flows
down the slope, accumulates in the swale,
and is blocked from exiting it by the dike.
The swale is graded to direct water slowly
downhill across the slope to a stabilized out-
let structure. Since flows are concentrated in
the swale, it is important to vegetate the
swale to prevent erosion of its channel and to
grade it so that predicted flows will not dam-
age the vegetation.
Pipe Slope Drains
Pipe slope drains are flexible pipes or
hoses used to traverse a slope that is already
damaged or at high risk of erosion. They are
often used in conjunction with some means
of blocking water flow on the slope, such as a
dike. Water collects against the dike and is
then channeled to one point along the dike
where it enters the pipe, which conveys it
downhill to a stabilized (usually riprap-lined)
outlet area at the bottom of the slope: You
should ensure that pipes are of adequate size
to accommodate the design storm event and
are kept clear of clogs.
Silt Fences, Straw Bales, and Brush Barriers
Silt fences and straw bales (see Figures 3
and 4) are temporary measures designed to
capture sediment that has already eroded and
reduce the velocity of storm water Silt fences
and straw bales should not be considered
permanent measures unless fences are main-
tained on a routine basis and straw bales are
replaced regularly. They could be used, for
example, during construction of a waste man-
agement unit or on a final cover before per-
manent grass growth is established.
Silt fences consist of geotextile fabric sup-
ported by wooden posts. These fences slow
the flow of storm water and retain sediment as
the water filters through the fabric. If properly
installed, straw bales perform a similar func-
tion. Straw bales should be placed end to end
(with no gaps in between) in a shallow, exca-
vated trench and staked into place. Silt fences
and straw bales limit sediment from entering
receiving waters if properly maintained. Both
measures require frequent inspection and
maintenance, including checking for channels
eroded beneath the fence or bales, removing
- What are some advantages of silt
fences, straw bales, and brush barriers?
They prevent eroded ^materials from
reachmgvsurface waters and prevent
downstream damage from sediment
deposits at minimal cost. ' ,, „
j* V" ">
JXi j'
What are some disadvantages of silt
fences/straw bales, and brush barriers?
These"measures are not appropriate
for streams or large swales and pose a
nsk of washouts if improperly rnstalle'd.
6-23
-------
Protecting Surface Water—Protecting Surface Water
accumulated sediment, and replacing dam-
aged or deteriorated sections.
Brush barriers work like silt fences and
straw bales but are constructed of readily
available materials. They consist of brush and
other vegetative debris piled in a row and are
often covered with filter fabric to hold them
in place and increase sediment interception.
Brash barriers are inexpensive due to their
reuse of material that is likely available from
clearing the site. New vegetation often grows
in the organic material of a brush barrier,
helping anchor the barrier with roots.
Depending on the material used, it might be
possible to leave a former brush barrier in
place and allow it to biodegrade, rather than
remove it.
Storm Drain Inlet Protection
Filtering measures placed around inlets or
drains to trap sediment are known as inlet
protection (see Figure 5). These measures
prevent sediment from entering inlets or
drains and possibly making their way to the
receiving waters into which the storm
drainage system discharges. Keeping sediment
out of storm-water drainage systems also
serves to prevent clogging, loss of capacity,
and other problems associated with siltation
of drainage structures. Inlet protection meth-
ods include sod, excavated areas for settle-
ment of sediment, straw bales or filter fences,
and gravel or stone with wire mesh. These
measures are appropriate for inlets draining
small areas where soil will be disturbed. Some
State or local jurisdictions require installation
of these measures before disturbance of more
than a certain acreage of land begins. Regular
maintenance to remove accumulated sedi-
ment is important for proper operation.
Collection and Sedimentation Basins
A collection or sedimentation basin (see
Figure 6) is an area that retains runoff long
Figure 3. Silt Fence
Bottom: Perspective of silt fence. Top: Cross-
section detail of base of silt fence.
From U.S. EPA, 1992e.
Figure 4. Straw Bale
From U.S. EPA, 1992e.
r
enough to allow most of the sediment to set-
tle out and accumulate on the bottom of the
basin. Since many pollutants are attached to
suspended solids, they will also settle out in
the basin with the sediment. The quantity of
sediment removed will depend on basin vol-
ume, inlet and outlet configuration, basin
depth and shape, and retention time. Regular
maintenance and dredging to remove accu-
-------
Protecting Surface Water—Protecting Surface Water
mulated sediment and to minimize growth of
aquatic plants that can reduce effectiveness is
critical to the operation of basins. All dredged
materials, whether they are disposed or
reused, should be managed appropriately.
Basins can also present a safety hazard.
Fences or other measures.to prevent unwant-
ed public access to the basins and their associ-
ated inlet and outlet structures are prudent
safety precautions. In designing collection or
sedimentation basins (a form of surface
impoundment), consider storm- water flow,
sediment and pollutant loadings, and the
characteristics of expected pollutants. In the
case of certain pollutants, it might be appro-
priate to line the basins to protect the ground
water below. Lining a basin with concrete also
facilitates maintenance by allowing dredging
vehicles to drive into a drained basin and
remove accumulated sediment. Poor imple-
mentation of baseline and activity-specific
BMPs can result in high sediment and pollu-
tant loads, leading to unusually frequent
' What are some advantages of '
sedimentation^ basins?
-, They protect downstream areas against
clogging or damage and contain smaller
.sediment particles"than sediment traps
can due to their Jonger retention time. *
What are sdmetdisadvantages?
Sedimentation basins are generally
>not suitable for large*areas, require regu-
lar maintenance and cleaning, and*will
• noj remove very fine slits and clays^
unless^used with other measures.
dredging of settled materials. For this reason,
when operating sedimentation basins, it is
important that baseline and activity-specific
BMPs are being implemented properly We
recommend that construction of these basins
be supervised by a qualified engineer familiar
with state and local storm-water requirements.
Figure 5. Storm Drain Inlet Protection
From U.S. EPA, 1992e.
Check Dams
Small-rock or log
dams erected across a
ditch, swale, or channel
can reduce the speed of
water flow in the con-
veyance. This reduces
erosion and also allows
sediment to.settle out
along the channel. Check
dams are especially use-
ful in steep, fast-flowing
swales where vegetation
cannot be established.
For best results, it is rec-
ommended that you
place check dams along
the swale so that the crest
of each check dam is at
the same elevation as the
toe (lowest point) of the
6-25
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Protecting Surface Water—Protecting Surface Water
previous (upstream) check dam. Check dams
work best in conveyances draining small
areas and should be installed only in man-
made conveyances. Placement of check dams
in streams is not recommended and might
require a permit.
Terraces and Benches
Terraces and benches are earthen embank-
ments with flat tops or ridge-and-channels.
Terraces and benches hold moisture and
minimize sediment loading in runoff. They
can be used on land with no vegetation or
where it is anticipated that erosion will be a
problem. Terraces and benches reduce ero-
sion damage by capturing storm-water runoff
and directing it to an area where the runoff
will not cause erosion or damage. For best
results, this area should be a grassy waterway,
vegetated" area, or tiled outlet. Terraces and
benches might not be appropriate for use on
sandy or rocky slopes.
Figure 6.
Collection and Sedimentation Basin
Flirt Vfe**
Outlet Protection
Stone, riprap, pavement, or other stabi-
lized surfaces placed at a storm-water con-
veyance outlet are known as outlet protection
(see Figure 7). Outlet protection reduces the
speed of concentrated storm-water flows exit-
ing the outlet, lessening erosion and scouring
of channels downstream. It also removes sed-
iment by acting as a filter medium. It is rec-
ommended that you consider installing outlet
protection wherever predicted outflow veloci-
ties might cause erosion.
d.
Infiltration
Infiltration measures such as vegetated fil-
ter strips, grassed swales, and infiltration
trenches encourage quick infiltration of
storm water into the ground rather than
allowing it to remain as overland flow.
Infiltration not only reduces runoff velocity,
but can also provide some treatment of
runoff, preserve natural stream flow, and
recharge ground water. Infiltration measures
can be inappropriate on unstable slopes or in
cases where runoff might be contaminated,
From U.S. EPA, 1992e.
' What'are some advantages of terraces
and benches? ^> ^ " '
•V /• y
, Terraces and benches reduce runoff ,••
> "" s "* •> \
speed and increase the distance of over-
land runoff flow In.addition, they'hold ->
moisture better than do smooth slopes -
and minimize sediment loading in tunoff.
' £ V ^
What are some disadvantages'of
terraces and,benches?
, - Terraces and benches can significantly
increase cut and fill costs'and cause',1'
sloughing if excess water infiltrates the ^,
soil.'They arejnot practical for sandy/
steep, or shallow soils; * ^
6-26
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Protecting Surface Water—Protecting Surface Water
or where wells, foundations, or septic fields
are nearby.
Vegetated Filter Strips and Grassed Swales
Vegetated filter strips are gently sloped
areas of natural or planted vegetation. They
allow water to pass over them in sheetflow
(runoff that flows in a thin, even layer), infil-
trate the soil, and drop sediment. Vegetated
filter strips are appropriate where soils are
well draining and the ground-water table is
deep below the surface. They will not work .
effectively on slopes of 15 percent or more
due to high runoff velocity. Strips should be
at least 20 feet wide and 50 to 75 feet long in
general, and longer on steeper slopes. If pos-
sible, it is best to leave existing natural vege-
tation in place as filter strips, rather than
planting new vegetation, which will not func-
tion to capture eroded particles until it
becomes established. -
Grassed swales function similarly to non-
vegetated swales (dispussed earlier in this
chapter) except that grass planted along the
swale bottom and sides will slow water flow
and filter out.sediment. Permeable soil in
which the swale is cut encourages reduction
of water volume through infiltration. Check
dams (discussed earlier in this chapter) are
sometimes provided in grassed swales to fur-
ther slow runoff velocity, increasing the rate
of infiltration.
To optimize swale performance, it is best
to use a soil which is permeable but not
excessively so; very sandy soils will not hold
vegetation well and will not form a stable
channel structure. It is also recommended
that you grade the swale to a very gentle
slope to maximize infiltration.
Infiltration Trenches
An infiltration trench (see Figure 8) is a
long, narrow excavation ranging from 3 to 12
feet deep. It is filled with stone to allow for
temporary storage of storm water in the open
spaces between the stones. The water eventu-
ally infiltrates the surrounding soil or is col-
lected by perforated pipes in the bottom of
the trench and conveyed to an'outflow point.
Such trenches can remove fine sediments and
Figure 7. Outlet Protection
From U.S. EPA, 1992e.
6-27
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Protecting Surface Water—Protecting Surface Water
soluble pollutants. They should not be built
in relatively impervious soils, such as clay,
that would prevent water from draining from
the bottom of the trench; less than 3 feet
above the water table; in soil that is subject
to deep frost penetration; or at the foot of
slopes steeper than 5 percent. Infiltration
trenches should not be used to handle conta-
minated runoff. Runoff can be pretreated
using a grass buffer/filter strip or treated in
the trench with filter fabric.
e. Other Practices
Additional practices exist that can help
prevent contamination of surface water such
as preventive monitoring, dust control, vehi-
cle washing, and discharge to wetlands.
Many of these practices are simple and inex-
pensive to implement while others, such as
monitoring, can require more resources.
Preventive Monitoring
Preventive monitoring includes automatic
and control systems, monitoring of opera-
tions by waste management unit personnel,
and testing of equipment. These processes
can help to ensure that equipment functions
as designed and is in good repair so that
spills and leaks, which could contaminate
adjacent surface waters, are minimized and
do not go undetected when they do occur.
Some automatic monitoring equipment, such
as pressure gauges coupled with pressure
relief devices, can correct problems without
human intervention, preventing leaks or
spills that could contaminate surface water if
allowed to occur. Other monitoring equip-
ment can provide early warning of problems
so that personnel can intervene before leaks
or spills occur. Systems that could contami-
nate surface water if they failed and that
could benefit from automatic monitoring or
early warning devices include leachate
pumping and treatment systems, liquid waste
Figure 8. Infiltration Trench
From U.S. EPA, 1992e.
distribution and storage systems at land
application units, and contaminated runoff
conveyances. :
Dust Control
In addition to being an airborne pollutant,
dust can settle in areas where, it can be
picked up by runoff or can be transported by
air and deposited directly into surface waters.
Dust particles can carry pollutants and can
also result in sedimentation of waterbodies.
Several methods of dust control are available
to prevent this. These include irrigation,
chemical treatments, minimization of
exposed soil areas, wind breaks, tillage, and
sweeping. For further information on dust
control, consult Chapter 8-Operating the
Waste Management System. •
Vehicle Washing - '
Materials that accumulate on tires and other
vehicle surfaces and then disperse across a
facility are an important source of surface-
water contamination. Vehicle washing removes
materials such as dust and waste. Washing sta-
tions can be located near waste transfer areas
or near the waste management site exit.
Pressurized water spray is usually sufficient to
remove dust. Waste water from vehicle wash-
ing operations should be contained and han-
6-28
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Protecting Surface Water—Protecting Surface Water
died appropriately. Discharge of such waste
water requires an NPDES permit other than
the Multi-Sector General Permit.
Discharges to Wetlands
Discharge to constructed wetlands is a
method less frequently used and can involve
complicated designs. The discharge of storm
water into natural wetlands, or the modifica-
tion of wetlands to improve their treatment
capacity, can damage a wetland ecosystem
and, therefore, is subject to federal, state, and
local regulations.
Constructed wetlands provide an alterna-
tive to natural wetlands. A specially designed
pond or basin, which is lined in some cases,
is stocked with wetland plants that can con-
trol sedimentation and manage pollutants
through biological uptake, microbial action,
and other mechanisms. Together, these
processes often result in better pollutant
removal than would be expected from sedi-
mentation alone. When designing construct-
ed wetlands, you should consider 1) that
maintenance might include dredging, similar
to that required for sedimentation basins, 2)
What are some advantages of ^
constructed wetlands7
Provide aesthetic as well as water qual-
ity benefits and areas for wildlife habitat
What are some disadvantages of -
constructed wetlands?
Discharges to wetlands might be sub-
ject to multiple federal, state, and local
regulations In addition, constructed
wetlands might not be feasible if land is
not available and might not be effective
as a storm-water control measure until
time has been allowed for substantial
plant growth.
provisions for a dry-weather flow to maintain
the wetlands, 3) measures to limit mosquito
breeding, 4) structures to prevent escape of
floating wetland plants (such as water
hyacinths) into downstream areas where they
are undesirable, and 5) a program of harvest-
ing and replacing plants.
B. Controls to Address
Surface-water
Contamination from
Ground Water to
Surface Water
Generally, the use of liners and ground-
water monitoring systems will reduce poten-
tial contamination from ground water to
surface water. For more information on pro-
tecting ground water, refer to Chapter 7:
Sections A-Assessing Risk, Section
B-Designing and Installing Liners, and
Section C-Designing a Land Application
Program.
C Controls to Address
Surface-water
Contamination from Air
to Surface Water
Emission control techniques for volatile
organic compounds (VOC) and particulates
can assist in reducing potential contamination
of surface water from air. Refer to Chapter
5-Protecting Air Quality, for more informa-
tion on air emission control techniques.
6-29
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Protecting Surface Water—Protecting Surface Water
V. Methods of
Calculating
Run-on and
Runoff Rates
The design and operation of surface-water
protection systems will be driven by antici-
pated storm-water flow. Run-on and runoff
flow rates for the chosen design storm event
should be calculated in order to: 1) choose
the proper type of storm-water controls to
install, and 2) properly design the controls
and size the chosen control measures to min-
imize impacts to surface water. Controls
based on too small a design storm event, or
sized without calculating flows will not func-
tion properly and can result in releases of
contaminated storm water. Similarly, systems
can also be designed for too large a flow,
resulting in unnecessary control and exces-
sive costs.
The usual approach for sizing surface-
water protection systems relies on the use of
standardized "design storms." A design storm
is, in theory, representative of many recorded
storms and reflects the intensity, volume, and
duration of a storm predicted to occur once
in a given number of years. In general, sur-
face-water protection structures should be
designed to handle the discharge from a 24-
hour, 25-year storm event (i.e., a rainfall
event of 24 hours duration and of such a
magnitude that it has a 4 percent statistical
likelihood of occurring in any given year).
Figure 9 presents a typical intensity-duration-
frequency curve for rainfall events.
The Hydrometeorological Design Studies
Center (HDSC) at the National Weather
Service has prepared Technical Paper 40,
Rainfall Frequency Atlas of the United States for
Durations From 30 Minutes to 24 Hours and
Return Periods From 1 to 100 Years (published
Rational Method for
Calculating Storm-Water
Runoff Flow
Q=.aa
where,
Q"=peak flow rate (runoff), expressed in
/cubic feet per second (cfs)*
''c = runoff coefficient, unitless The coeffi-
cient c is not directly calculable, so
" average values based on experience
are used Values of c range from 0 (all
infiltration, no runoff) to 1 (all
runoff, no infiltration) For example,
flat lawns with sandy soil have a c
value of 0 05 to i).10, while concrete
streets have a c value of 0.80 to 0 95.
\ = average rainfall intensity, expressed
in inches per hour, for the time of
concentration, tc, which is a calcula-
ble flow time from the most distant
point m the drainage area to the
point at which Q is being calculated
Qnce tc is calculated and a design
storm event frequency is selected, i
" can be obtained from rainfall ihten-
** " sity-duration-frequency graphs (see
Figure 9) ^
a - drainage area, expressed m acres.
; --The drainage area is the expanse in
which all runoff flows to the point
at, which Q is being calculated.
. * Examining the units of i and a would
indicate that Q should,be in units of
ac-m/hr However, since 1 ac-m/hr =
, 1.008 cfs, the units are interchangeable
"with a tiegligiblejoss of accuracy Units
of cfs^are usually desired for subse-
quent'calculations 0
6-30
-------
Protecting Surface Water—Protecting Surface Water
in 1961). This document contains rainfall
intensity information for the entire United
States. Another HDSC document, NOAA Atlas
2, Precipitation Frequency Atlas of the Western
United States (published in 1973) comes in 11
volumes, one for each of the 11 westernmost ,
of the contiguous 48 states. Precipitation fre-
quency maps for the eleven western most
states are available on the Western Regional
Climate Center's Web page at . HDSC is cur-
rently assembling more recent data for some
areas. Your state or local regulatory agency
might be able to provide data for your area.
Several methods are available to help you
calculate storm-water flows. The Rational
Method can be used for calculating runoff for
areas of less than 200 acres. Another useful
tool for estimating storm-water flows is the
Natural Resource Conservation Service's TR-
55 software.5 TR-55 estimates runoff volume
from accumulated rainfall and then applies
the runoff volume to a simplified hydrograph
for peak discharge total runoff estimations:
Computer models are also available to aid
in the design of storm-water control systems.
For example, EPA's Storm Water
Management Model (SWMM) is a compre-
hensive model capable of simulating the
movement of precipitation and pollutants
from the- ground surface through pipe and
channel networks, storage treatment units,
and finally to receiving water bodies. Using
SWMM, it might be possible w perform both
single-event and continuous simulation on
Figure 9. Typical Intensity-Duration-
Frequency Curves
-
\
\v
\\
V
T frequency
50-yr frequency
20-yr frequency,
. 10-yr frequency
. 5-yr frequency
60
Duration (rain)
From WATER SUPPLY AND POLLUTION CON-
TROL, 5th Edition, by Warren Viessman, Jr. and
Mark J. Hammer; Copyright (©) 1993 by Harper
Collins College Publishers. Reprinted by permis-
sion of Addison-Wesley Educational Publishers.
catchments having storm sewers and natural
drainage, for prediction of flows, stages, and
pollutant concentrations.
Some models, including SWMM, were
developed for purposes of urban storm-water
control system design, so it is important to
ensure that their methodology is applicable to
the design of industrial waste management
units. As with all computer models, these
should be used as part of the array of design
tools, rasher than as a substitute for careful
consideration of the unit's design by qualified
professionals.
TR-55, Urban Hydrology for Small Watersheds Technical Release 55, presents simplified procedures to
calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes required for
floodwater reservoirs. This software is suited for use in small and especially urbanizing watersheds. TR-
55 can be downloaded from the National Resource Conservation Service at
.
6-31
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Protecting Surface Water—Protecting Surface Water
Storm Water Management Model (SWMM). Simulates the movement of precipitation
and pollutants from the ground surface through pipe and channel networks, storage treat-
ment units, and receiving waters. " 5 v
BASINS: A Powerful Tool for Managing Watersheds. A multi-purpose environmen-
tal analysis system that integrates a geographical information system (GIS), national water-
shed data, and state-of-the-art environmental assessment and modeling tools into one
package. - ^ • ^
Source Loading and Management Model (SLAMM). Explores relationships between
sources of urban runoff pollutants and runoff quality. It includes a wide variety of source
area and outfall control practices., SLAMM is strongly based on actual field observations,
with minimal reliance on theoretical processes that have not been adequately documented
or confirmed in the field. SLAMM is mostly-used as a planning tool, to better understand
sources of urban runoff pollutants and their control. ,
Simulation for Water Resources in Rural Basins (SWRRB). Simulates hydrologic,
sedimentation, and nutrient and pesticide transport in large, complex rural watersheds. It
can predict the effect of management decisions on water, sediment, and pesticide yield
with seasonable accuracy for ungauged rural basins throughput the United States.
Pollutant Routing Model (P-ROUTE). Estimates aqueous pollutant concentrations on
a stream reach by stream reach flow basis, using 7Q10 or mean flow/' _
Enhanced Stream Water Quality Model (QUAL2E). Simulates jthe major reactions of
nutrient cycles, algal production, benthic and carbonaceous demand, atmospheric reaera-
tion and their effects on the dissolved oxygen balance. It is intended as a water quality
planning tool for developing total maximum daily loads (TMDLs) and can also be used in
conjunction widi field sampling for identifying the magnitude and quality characteristics
of nonpointsources. X '''„,-. ", ~
6-32
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Protecting Surface Water—Protecting Surface Water
Protecting Surface Water Activity List
You should conduct the following activities when designing or operating surface-water
protection measures or systems in conjunction with waste management units.
D Comply with applicable National Pollutant Discharge Elimination System (NPDES),
state, and local permitting requirements.
Q Assess operating practices, identify potential pollutant sources, determine what con-
stituents in the unit pose the greatest threats to surface water, and calculate storm-
water runoff flows to determine the need for and type of storm-water controls.
D Choose a design storm event (e.g., a 24-hour, 25-year event) and obtain precipita-
tion intensity data for that event to determine the most appropriate storm-water con-
trol devices.
Q Select and implement baseline and activity-specific BMPs, such as good housekeep-
ing practices and spill prevention and response plans as appropriate for your waste
management unit.
D Select and establish site-specific BMPs, such as diversion dikes, collection and sedi-
mentation basins, and infiltration trenches as appropriate for your waste manage-
ment unit.
n Develop a plan for inspecting and maintaining the chosen storm-water controls; if
possible, include diese measures as part of the operating plan for the waste manage-
ment unit.
6-33
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Protecting Surface Water—Protecting Surface Water
Resources
Dingman, S. 1994. Physical Hydrology. Prentice Hall.
Florida Department of Environmental Regulation. Storm Water Management: A Guide for Floridians.
Novotny, V, and H. Olem. 1994. Water Quality: Prevention, Identification, and Management of Diffuse
Pollution. Van Nostrand Reinhold. ,
Pitt, R. 1988. Source Loading and Management Model: An Urban Nonpoint Source Water Quality Model
(SLAMM). University of Alabama at Birmingham.
McGhee, T. 1991. McGraw-Hill Series in Water Resources and Environmental Engineering. 6th Ed.:
Urbonas, B., and P. Stahre. 1993. Storm Water: Best Management Practices and Detention for Water Quality,
Drainage, and CSO Management. PTR Prentice Hall.
U.S. EPA. 1999. Introduction to the National Pretreatment Program. EPA833-B-98-002. !
U.S. EPA. 1998. Water Quality Criteria and Standards Plan-Priorities for the Future. EPA822-R-98-003.
U.S. EPA. 1995a. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage. EPA625-
R-95-001.
U.S. EPA. 1995b. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage: EPA625-
R-95-002. ;
U.S. EPA. 1995c. NPDES Storm Water Multi-Sector General Permit Information Package.
U.S. EPA. 1995d. Storm Water Discharges Potentially Addressed by Phase II of the National Pollutant
Discharge Elimination System Storm Water Program. Report to Congress. EPA833-K-94-002. ;
U.S. EPA. 1994a. Introduction to Water Quality Standards. EPA823-B-95-004. ;
U.S. EPA. 1994b. Project Summary: Potential Groundwater Contamination from Intentional and Non-
Intentional Storm Water Infiltration. EPA600-SR-94-061.
U.S. EPA. 1994c. Storm Water Pollution Abatement Technologies. EPA 600-R-94-129.
6-34
-------
Protecting Surface Water—Protecting Surjaca Water
Resources (cont.)
U.S. EPA. 1993a. Overview of the Storm Water Program. EPA833-F-93-001.
U.S. EPA. 1993b. NPDES Storm Water Program: Question and Answer Document, Volume 2. EPA833-
F093-002B.
U.S. EPA. 1992a. An Approach to Improving Decision Making in Wetland Restoration and Creation.
EPA600-R-92-150.
U.S. EPA. 1992b. NPDES Storm Water Program: Question and Answer Document, Volume 1. EPA833-F-
93-002.
U.S. EPA. 1992c. NPDES Storm Water Sampling Guidance Document. EPA833-B-92-001.
U.S. EPA. 1992d. Storm Water General Permits Briefing. EPA833-E-93-001.
U.S. EPA. 1992e. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans
and Best Management Practices. EPA832-R-92-006.
U.S. EPA. 1992f. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans
and Best Management Practices. Summary Guidance. EPA833-R-92-002.
Viessmanjr., W, and M.J. Hammer. 1985. Water Supply and Pollution Control. 4th Ed.
Washington State Department of Ecology. 1993. Storm Water Pollution Prevention Planning for Industrial
Facilities: Guidance for Developing Pollution Prevention. Plans and Best Management Practices. Water
Quality Report. WQ-R-93-015. September.
6-35
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Part IV
Protecting Ground-Water Quality
Chapter 7: Section A
Assessing Risk
-------
-------
Contents
I. Assessing Risk 7A-3
A. General Overview of the Risk Assessment Process 7A-3
1. Problem Formulation 7A-3
2. Exposure Assessment 7A-4
3. Toxicity Assessment 7A-5
4. Risk Characterization 7A-5
B. Ground-Water Risk 7A-6
1. Problem Formulation 7A-6
2. Exposure Assessment 7^_7
3. Toxicity Assessment 7A-11
4.Risk Characterization 7A-12
II. The IWEM Ground-Water Risk Evaluation 7A-14
A. The Industrial Waste Management Evaluation Model (IWEM) 7A-15
1. Leachate Concentrations 7A-16
2. Models Associated with IWEM 7A-16
3. Important Concepts for Use of IWEM 7A-18
B. Tier 1 Evaluations 7A-22
1. How Are the Tier 1 Lookup Tables Used? 7A-23
2. What Do the Results Mean and How Do I Interpret Them? 7A-25
C. Tier 2 Evaluations _ 7A-P7
1. How is a Tier 2 Analysis Performed? 7A-77
2. What Do the Results Mean and How Do I Interpret Them? 7A-32
D. Strengths and Limitations 7A-34
1. Strengths 7A_34
2. Limitations 7A-34
E. Tier 3: A Cornprelrensrve Sitte-Specific Evaluation 7A-35
1. How is a Tier 3 Evaluation Performed? 7A-35
Assessing Risk Activity List 7A-40
Resources: 7A-41
Tables:
Table 1. Earth's Water Resources jj±_i
Table 2. Examples of Attenuation Processes 7A-10
Table 3. List of Constituents in IWEM with Maximum Contaminant Levels (MCLs) .7A-13
-------
Contents
Table 4. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - No Liner/In situ Soils ..7A-24
Table 5. Example of Tier 1 Summary Table for HBN-based LCTVs for Landfill - No Liner/In situ Soils 7A-25
Table 6. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Single Clay Liner 7A-25
Table 7. Example of Tier 1 Summary Table for MCL-based LCTVs for Landfill - Composite Liner 7A-25
Table 8. Input Parameters for Tier 2 1 7A-29
Table 9. A Sample Set of Site-Specific Data for Input to Tier 2 7A-31
Table 10. Example of Tier 2 Detailed Summary Table - No Liner/In situ Soils ; .....7A-31
Table 11. Example of Tier 2 Detailed Summary Table - Single Clay Liner •. 7A-32
Table 12. Example Site-Specific Ground-water Fate and Transport Models 7A-38
Table 13. ASTM Ground-Water Modeling Standards 7A-39
Figures:
Figure 1: Representation of Contaminant Plume Movement 7A-5
Figure 2: Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial
Waste Guidelines ; 7A-22
Figure 3: Using Tier 1 Lookup Tables • - 7A-27
-------
Protecting Ground Water—Assessing Risk
Assessing Risk
This chapter will help you:
• Protect ground water by assessing risks associated with new waste
management units and tailoring management controls accordingly.
• Understand the three-tiered evaluation discussed in this chapter
that can be used to determine whether a liner system is necessary,
and if so, which liner system is recommended, or whether land
application is appropriate.
• Follow guidance on liner design and land application practices.
Ground water is
the water found
in the soil and
rock that make
up the Earths
surface. Although it corn-
prises only about 0.69 per-
cent of the Earths water
resources, ground water is of
great importance. It repre-
sents, about 25 percent of
fresh water resources, and
when the largely inaccessible
fresh water in ice caps and
glaciers is discounted,
ground water is the Earth's
largest fresh water
resource—easily surpassing
lakes and rivers, as shown in Table 1.
Statistics about the use of ground water as a
drinking water source underscore the impor-
tance of this resource. Ground water is a
source of drinking water for more than half of
the people in the United States.1 In rural
areas, 97 percent of households rely on
ground water as their primary source of
drinking water.
In addition to its importance as a domestic
water supply, ground water is heavily used by
industry and agriculture. It provides approxi-
mately 37 percent of the irrigation water and 18
Table 1.
Earth's Water Resources
Resource " r Percent of •" Percent of
, Total- Nonoceariic
Oceans
Ice caps and glaciers
Ground water and soil moisture
Lakes and rivers
Atmosphere
Biosphere
97.25
2.05 -
0.685
0.0101
0.001
0.00004
—
74.65
24.94
0.37
0.036
0.0015
Adapted from Berner, E.K. and R. Berner. 1987. The Global
Water Cycle: Geochemistry and Environment
percent of the total water used by industry2
Ground water also has other important environ-
mental functions, such as providing recharge to
lakes, rivers, wetlands, and estuaries.
Water beneath the ground surface occurs in
an upper unsaturated (vadose) zone and a
deeper saturated zone. The unsaturated zone
is the area above the water table where the
soil pores are not filled with water, although
some water might be present. The subsurface
area below the water table where the pores
and cracks are filled with water is called the
saturated zone. This chapter focuses on
Surface water, in the form of lakes and rivers, is the other major drinking water source. Speidel, D., L.
Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses.
Excludes cooling water for steam-electric power plants. U.S. Geological Survey. 1998. Estimated Use of
Water in the United States in 1995.
7A-1
-------
Protecting Ground Water—Assessing Risk
ground water in the saturat-
ed zone, where most
ground-water withdrawals
are made.
Because ground water is a
major source of water for
drinking, irrigation, and
process water, many different
parties are concerned about
ground-water contamination,
including the public; indus-
try; and federal, state, and
local governments. Many
potential threats to the quali-
ty of ground water exist,
such as the leaching of fertil-
izers and pesticides, contam-
ination from faulty or
overloaded septic fields, and
releases from industrial facil-
ities, including waste man-
agement units.
If a source of ground
water becomes contaminat-
ed, remedial action and
monitoring can be costly.
Remediation can require
years of effort, or in sortie
circumstances, might be
technically infeasible. For
these reasons, preventing
ground-water contamination
is important, or at least min-
imizing impacts to ground
water by implementing con-
trols tailored to the risks
associated with the waste.
This chapter addresses how ground-water
resources can be protected through the use of
a systematic approach of assessing potential
risk to ground water from a proposed waste
management unit (WMU). It discusses assess-
ing risk and the three-tiered ground-water risk
assessment approach implemented in the
A Ground Water-in the Hydrologic Cycle ^
> * ^ "V Jgyfr^ " s ^ t f
The hydrologic cycle involves the continuous movement of"'
water between the atmosphere, surface-water, and the
ground Ground water must be, understood in relation to *
both surface water and atmospheric moisture Most addi-r
tions (recharge) to ground water corne from the atmosphere
in the form of precipitation, but^surface water in streams,
rivers, and lakes will move into the ground-water-system
wherever the hydraulic head of the water surface is higher *'
' - \\s> f. "f», „ O xt
than the water table. Most water entering the ground as pre-
cipitation returns to the atmosphere by evapotransplration .
Most water that reaches the saturated zone eventually
returns to the surface by flowing to points of discharge,'
such as rivers', lakes, or;spnngs. Soilf^geology, and climate
will determine the amounts and rates of flow among trie-
atmospheric, surface, and grouncl-water systems.^ <. "'
Industrial Waste Management Evaluation
Model (IWEM), which was developed as part
of this Guide. Additionally, the chapter dis-
cusses the use of this tool and how to apply
its results and recommendations. It is; highly
recommended that you also consult with your
state regulatory agency, as appropriate. More
specific information on the issues described in
7A-2
-------
Protecting Ground "Water—Assessing Risk
this chapter is available in the companion
documents to the IWEM software: User's
Guide for the Industrial Waste Management
Evaluation Model (U.S. EPA, 2002b), and
Industrial Waste Management Evaluation Model
(IWEM) Technical Background Document (U.S.
EPA, 20Q2a).
I. Assessing Risk
A. General Overview of the
Risk Assessment Process
Our ground-water resources are essential
for biotic life on the planet. They also act as a
medium for the transport of contaminants
and, therefore, constitute an exposure path-
way of concern. Leachate from WMUs can be
a source of ground-water contamination.
Residents who live close to a WMU and who
use wells for water supply can be directly
exposed to waste constituents by drinking or
bathing in contaminated ground water.
Residents .also can be exposed by inhaling
volatile organic compounds (VOCs) and
semi-volatile organic compounds (SVOCs)
that are released indoors while using ground
water for showering or via soil gas migration
from subsurface plumes.
The purpose of this section is to provide
general information on the risk assessment
process and a specific description of how
each of the areas of risk assessment is applied
in performing ground-water risk analyses.
Greater detail on each of the steps in the
process as they relate to assessing ground-
water risk is provided in later sections of this
chapter.
In any risk assessment, diere are basic
steps that are necessary for gathering and
evaluating data. This Guide uses a four-part
process to estimate the likelihood of chemi- .
cals coming into contact with people now or
in the future, and the likelihood that such
contact will harm these people. This process
shows how great (or small) the risks might
be. It also points to who is at risk, what is
causing the risk, and how certain one can be
about the risks. A general overview of these
steps is presented below to help explain how
the process is used in performing the assess-
ments associated with IWEM. The compo-
nents of a risk assessment that are discussed
in this section are: problem formulation,
exposure assessment, toxicity assessment, and
risk characterization. Each of these steps is
described as it specifically applies to risk
resulting from the release of chemical con-
stituents from WMUs to ground water.
1. Problem Formulation
The first step in the risk assessment
process is problem formulation. The purpose
of this step is to clearly define the risk ques-
tion to be answered and identify the objec-
tives, scope, and boundaries of the
assessment. This phase can be viewed as
developing the overall risk assessment study
design for a specific problem. Activities that
might occur during this phase include:
• Articulating a clear understanding of
. the purpose and intended use of the
risk assessment.
• Identifying the constituents of concern.
• Identifying potential release scenarios.
• Identifying potential exposure path-
ways. '
• Collecting and reviewing available
data.
• . Identifying data gaps.
• Recommending data collection
efforts.
• Developing a conceptual model of
what is occurring at the site.
7A-3
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Protecting Ground Water—Assessing Risk
Although this step can be formal or infor-
mal, it is critical to the development of a suc-
cessful assessment that fully addresses the
problem at hand. In addition, the develop-
ment of a conceptual model helps direct the
next phases of the assessment and provides a
clear understanding of the scope and design
of the assessment.
2. Exposure Assessment
The goals of an exposure assessment are
to: 1) characterize the source, 2) characterize
the physical setting of the area that contains
the WMU, 3) identify potential exposure
pathways, 4) understand the fate and trans-
port of constituents of concern, and 5) calcu-
late constituent doses.
Source characterization involves defining
certain key parameters for the WMU. The
accuracy of predicting risks improves as more
site-specific information is used in the char-
acterization. In general, critical aspects of the
source (e.g., type of WMU, size, location,
potential for leachate generation, and expect-
ed constituent concentrations in leachate)
should be obtained. Knowledge of the overall
composition of the waste deposited in the
WMU and of any treatment processes occur-
ring in the WMU is important to determine
the overall characteristics of the leachate that
will be generated.
The second step in evaluating exposure is
to characterize the site with respect to its
physical characteristics, as well as those of
the human populations near the site.
Important site characteristics include climate,
meteorology, geologic setting, and hydrogeol-
ogy. Consultation with appropriate technical
experts (e.g., hydrogeologists, modelers)
might be needed to characterize' the site.
Characterizing the populations near the site
with respect to proximity to the site, activity
patterns, and the presence of sensitive sub-
groups might also be appropriate. This group
of data will be useful in determining the
potential for exposure to and intake of con-
stituents. •
The next step in this process includes
identifying exposure pathways through
ground water and estimating exposure con-
centrations at the well3. In modeling the
movement of the constituents away from the
WMU, the Guide generally assumes that the
constituents behave as a plume (see Figure
1), and the plumes movement is modeled to
produce estimated concentrations of con-
stituents at points of interest. As shown in
Figure 1, the unsaturated zone receives
leachate from the WMU. In general, the flow
in the unsaturated zone tends to be gravity-
driven, although other factors (e.g., soil
porosity, capillarity, moisture potential) can
also influence downward flow.
Transport through the unsaturated zone
delivers constituents to the saturated zone, or
aquifer. Once the contaminant arrivesj at the
water table, it will be transported downgradi-
ent toward wells by the predominant flow
field in the saturated zone. The flow field is
governed by a number of hydrogeologic and
climate-driven factors, including regional
hydraulic gradient, hydraulic conductivity of
the saturated zone, saturated zone thickness,
local recharge rate (which might already be
accounted for in the regional hydraulic gradi-
ent), and infiltration rate through the WMU.
The next step in the process is to estimate
the exposure concentrations at a well. Many
processes can occur in the unsaturated zone
and in the saturated zone that can influence
the concentrations of constituents in leachate
in a downgradient well. These processes
include dilution and attenuation, partitioning
to solid, hydrolysis, and degradation.
Typically, these factors should be considered
when estimating the expected constituent
concentrations at a receptor.
3 In this discussion and in IWEM, the term "well" is used to represent an actual or hypothetical ground-
water monitoring well or drinking water well, located downgradient from a WMU. !
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Protecting Ground Water—Assessing Risk
Figure 1: Representation of Contaminant Plume Movement
Waste Management Unit
Well
Land Surface
Saturated
Zone Leachate Plume
The final step in this process is estimating
the dose. The dose is determined based on
the concentration of a constituent in a medi-
um and the intake rate of that medium for
the receptor. For example, the dose is depen-
dent on the concentration of a constituent in
a well and the ingestion rate of ground water
from that well by the receptor. The intake
rate is dependent on many behavior patterns,
including ingestion rate, exposure duration,
and exposure frequency. In addition, a risk
assessor should consider the various routes of
exposure (e.g.1, ingestion, inhalation) to deter-
mine a dose.
After all of this information has been col-
lected, the exposure pathways at the site can
be characterized by identifying the potentially
exposed populations, exposure media, expo-
sure points, and relevant exposure routes and
then calculating potential doses.
3. Toxicity Assessment
The purpose of .a toxicity assessment is to
weigh available evidence regarding the poten-
tial for constituents to .cause adverse effects in
exposed individuals. It is also meant to pro-
vide, where possible, an estimate of the rela-
tionship between the extent of exposure to a
constituent and the increased likelihood
and/or severity of adverse effects. The intent
is to establish a dose-response relationship
between a constituent concentration and the
incidence ofan adverse effect. It is usually a
five-step process that includes: 1) gathering
toxicity information for the substances being
evaluated, 2) identifying the exposure periods
for which toxicity values are necessary, 3)
determining the toxicity values for noncar-
cinogenic effects, 4) determining the toxicity
values for carcinogenic effects, and 5) sum-
marizing the toxicity information. The deriva-
tion and interpretation of toxicity values
requires toxicological expertise and should
not be undertaken by those without training
and experience. It is recommended that you
contact your state regulatory agency for more
specific guidance.
4. Risk Characterization
This step involves summarizing and inte-
grating the toxicity and exposure assessments
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Protecting Ground Water—Assessing Bisk
and developing qualitative and quantitative
expressions of risk. To characterize noncar-
cinogenic effects, comparisons are made
between projected intakes of substances and
toxicity values to predict the likelihood that
exposure would result in a non-cancer health
problem, such as neurological effects. To char-
acterize potential carcinogenic effects, the
probability that an individual will develop
cancer over a lifetime of exposure is estimated
from projected intake and chemical-specific
dose-response information. The dose of a par-
ticular contaminant to which an individual
was exposed—determined during the expo-
sure assessment phase—is combined with the
toxicity value to generate a risk estimate.
Major assumptions, scientific judgements,
and, to the extent possible, estimates of the
uncertainties embodied in the assessment are
also presented. Risk characterization is a key
step in the ultimate decision-making process.
B. Ground-Water Risk
The previous section provided an overview
of risk assessment; this section provides more
detailed information on conducting a risk
assessment specific to ground water. In partic-
ular, this section characterizes the phases of a
risk assessment—problem formulation, expo-
sure assessment, toxicity assessment, and risk
characterization—in the context of a ground-
water risk assessment.
7. Problem Formulation
The intent of the problem formulation
phase is to define the risk question to be
answered. For ground-water risk assessments,
the question often relates to whether releases
of constituents to the ground water are pro-
tective of human health, surface 'water, or
ground-water resources. This section discuss-
es characterizing the waste and developing a
conceptual model of a site.
a.
Waste Characterization
A critical component in a ground-water
risk assessment is the characterization of the
leachate released from a WMU. Leachate is
the liquid formed when rain or other water
comes into contact with waste. The character-
istics of the leachate are a function of the
composition of the waste and other factors
(e.g., volume of infiltration, exposure, to dif-
fering redox conditions, management of the
WMU). Waste characterization includes both
identification of the potential constituents1 in
the leachate and understanding the physical
and chemical properties of the wastes
Identification of the potential constituents
in leachate requires a thorough understanding
of the waste that will be placed in a WMU.
Potential constituents include those used in
typical facility processes, as well as degrada-
tion products from these constituents. For
ground-water risk analyses, it is important to
not only identify the potential constituents of
concern in the leachate, but also the likely
concentration of these constituents in leachate.
To assist in the identification of constituents
present in leachate, EPA has developed several
leachate tests including the Toxicity '
Characteristic Leaching Procedure (TCLP), the
Synthetic Precipitation Leaching Procedure
(SPLP), and the Multiple Extraction Procedure
(MEP). These and other tests that .cm be used
to characterize leachate are discussed more
fully in Chapter 2—Characterizing Waste and
are described in EPA's SW-846 Test Methods for
Evaluating Solid Wastes (U.S. EPA, 199,6 and as
updated).
In addition to identifying the constituents
present, waste characterization includes
understanding the physical, biological, and
chemical properties of the waste. The physical
and chemical properties of the waste stream
affect the likelihood and rate that constituents
will move through the WMU. For example,
the waste properties influence the partitioning
7A-6
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Protecting Ground Water—Assessing Risk
of constituents among .the aqueous, vapor,
and solid phases. Temperature, pH, pressure,
chemical composition,4 and the presence of
microorganisms within WMUs may have sig-
'nificant effects on the concentration of con-
stituents available for release in the leachate.
Another waste characteristic that can influ-
ence leachate production is the presence of
organic wastes as free liquids, also called
non-aqueous phase liquids (NAPLs). The
presence of NAPLs'may affect the mobility of
constituents based on saturation and viscosi-
ty. Finally, characteristics such as acidity and
alkalinity can influence leachate generation
by affecting the permeability of underlying
soil or clay.
b. Development of a Conceptual
Model
The development of a conceptual model is
important for defining what is needed for the
exposure assessment and the toxicity assess-
ment. The conceptual model identifies the
major routes of exposure to be evaluated and
presents the current understanding of the
toxicity of the constituents of concern.
For the ground-water pathway, the concep-
tual model identifies those pathways on
which-the risk assessor should focus.
Potential pathways of interest include ground
water used as drinking water, ground water
used for other domestic purposes that might
release volatile organics, ground-water releas-
es to surface water, vapor intrusion from
ground-water gases to indoor air, and ground
water used as irrigation water. The conceptu-
al model should address the likelihood of
various ground-water pathways under present
or future circumstances, provide insight to
the likelihood of contact with receptors
through the various pathways, and identify
areas requiring further information.
The conceptual model should also address
the toxicity of the constituents of concern.
Information about constituent toxicity can be
collected from publicly available resources
such as the Integrated Risk Information
System (IRIS) or from
detailed, chemical-specific literature searches.
The conceptual model should attempt to
identify the toxicity data that are most rele-
vant to likely routes of ground-water expo-
sure and identify areas requiring 'additional
research. The conceptual model should pro-
vide a draft plan of action for die next phases
of the risk assessment.
2. Exposure Assessment
Exposure assessment is generally com-
prised of two components: characterization of
the exposure setting and identification of the
exposure pathways. Characterization of the
exposure setting includes describing the
source characteristics and the site characteris-
tics. Identification of the exposure pathway
involves understanding the process by which
a constituent is released from a source, travels
to a receptor, and is taken up by the receptor.
This section discusses the concepts of charac-
terizing the source, characterizing the site set-
ting, understanding the general dynamics of
contaminant fate and transport (or movement
of harmful chemicals to a receptor), identify-
ing exposure pathways, and calculating the
dose to (or uptake by) a receptor.
a.
Source Characterization
The characteristics of a source greatly
influence the release of leachate to ground
water. Some factors to consider include the
type ofWMU, the size of the unit, and the
design and management of the unit. The type
of WMU is important because each unit has
distinct characteristics that affect release.
Landfills, for example, tend to be permanent
in nature, which provides a long time period
for leachate generation. Waste piles, on the
other hand, are temporary in design and
4 Generally, the model considers a high ratio of solids to leachate, and therefore, the user should consider
this before applying a 20 to 1 solids to leachate ratio.
7A-7
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Protecting Ground Water—Assessing Risk
allow the user to remove the source of conta-
minated leachate at a future date. Surface
impoundments, which are generally managed
with standing water, provide a constant
source of liquid for leachate generation and
potentially result in greater volumes of
leachate.
The size of the unit is important because
units with larger areas have the potential to
generate greater volumes of contaminated
leachate than units with smaller areas. Also,
units such as landfills that are designed with a
greater depth below the ground's surface can
result in decreased travel time from the bot-
tom of the unit to the water table, resulting in
less sorption of constituents. In some cases, a
unit might be hydraulically connected with
the water table resulting in no attenuation in
the unsaturated zone.
The design of the unit is important because
it might include an engineered liner system
that can reduce the amount of infiltration
through the WMU, or a cover that can reduce
the amount of water entering the WMU.
Typical designs might include compacted clay
liners or geosynthetic liners. For surface
impoundments, sludge layers from compacted
sediments might also help reduce the amount
of leachate released. The compacted sedi-
ments can have a lower hydraulic conductivi-
ty than the natural soils resulting in slower
movement of leachate from the bottom of the
unit. Covers also affect the rate of leachate
generation by limiting the amount of liquid
that reaches the waste, thereby limiting the
amount of liquid available to form leachate.
Co-disposal of different wastes can result in
increased or decreased rates of leachate gener-
ation. Generally, WMUs with appropriate
design specifications can result in reduced
leachate generation.
b.
Site Characterization
Site characterization addresses the, physical
characteristics of the site as well as the popu-
lations at or near the site. Important physical
characteristics include the climate, geology,
hydrology, and hydrogeology. These physical
characteristics help-define the likelihood that
water might enter the unit and the likelihood
that leachate might travel from the bottom of
the unit to the ground water. For example,
areas of high rainfall are more likely to gener-
ate leachate than arid regions. The geology of
the site also can affect the rate of infiltration
through the unsaturated zone. For example,
areas with fractured bedrock can allow
leachate through more quickly than a packed
clay material with a low hydraulic conductivi-
ty. Hydrology should also be considered
because ground water typically discharges to
surface water. The presence of surface waters
can restrict flow to wells or might require
analysis of the impact of contaminated ground
water on receptors present in die surface
water. Finally, factors related to the hydrogeol-
ogy, such as the depth to the water table, also
influence the rate at which leachate reaches
the water table. :
The characterization of the site also includes
identifying and characterizing populations at
or near the site. When characterizing popula-
tions, it is important to identify the relative
location of the populations to the site. For
example, it is important to determine whether
receptors are downgradient from the :unit and
die likely distance from the unit to -wjells. It is
also important to determine typical activity
patterns, such as whether ground water is
used for drinking water or agricultural purpos-
es. The presence of potential receptors is criti-
cal for determining a complete exposure
pathway. People might not live there :now, but
they might live there in 50 years, based on
future use assumptions. State or local agencies
have relevant information to help you identify
7A-8
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Protecting Ground "Water—Assessing Risk
areas that are designated as potential sources
of underground drinking water.
c. Understanding Fate and Transport
In general, the flow in the unsaturated zone
tends to be gravity-driven. As shown in Figure
1, the unsaturated zone receives leachate infil-
tration from the WMU. Therefore, the vertical
flow component accounts for most of the fluid
flux between the base of the WMU and the
water table. Water-borne constituents are car-
ried vertically downward toward the water
table by the advection process. Mixing and
spreading occur as a result of hydrodynamic
dispersion and diffusion. Transport processes
in the saturated zone include advection,
hydrodynamic dispersion, and sorption.
Advection is the process by which con-
stituents are transported by the motion of the
flowing ground water. Hydrodynamic disper-
sion is the tendency for some constituents to
spread out from the path that they would be
expected to flow. Sorption is the process by
which leachate molecules adhere to the sur-
face of individual clay, soil, or sediment parti-
cles. Attenuation of some chemicals in the
unsaturated zone is attributable to various
biochemical or physicochemical processes,
such as degradation and sorption.
The type of geological material below the
unit affects the rate of movement because of
differences in hydraulic and transport proper-
ties. One of the key parameters controlling
contaminant migration rates is hydraulic con-
ductivity. The larger the hydraulic conductivi-
ty, the greater the potential migration rate due
to lower hydraulic resistance of the formation.
Hydraulic conductivity values of some hydro-
geologic environments, such as bedded sedi-
mentary rock aquifers, might not be as large
as those of other hydrogeologic environments,
such as sand and gravel or fractured lime-
stone. As a general principle, more rapid
movement of waste constituents can be
expected through coarse-textured materials,
such as sand and gravel, than through fine-
textured materials, such as silt and clay. Other
key flow and transport parameters include
dispersivity (which determines how far a
plume will spread horizontally and vertically
as it moves away from the source) .and porosi-
ty (which determines the amount of pore
space in the geologic materials in the unsatu-
rated and saturated zone used for flow and
transport and can affect transport velocity).
As waste constituents migrate through the
unsaturated and saturated zones, they can
undergo a number of biochemical and
physicochemical processes that can lead to a
reduction in concentration of potential
ground-water contaminants. These processes
are collectively referred to as attenuation
processes. Attenuation processes can remove
or degrade waste constituents through filtra-
tion, sorption, precipitation, hydrolysis, bio-
logical degradation, bio-uptake, and redox
reactions. Some of these processes (e.g.,
hydrolysis, biological degradation) can actual-
ly result in the formation of different chemi-
cals and greater toxicity. Attenuation
processes are dependent upon several factors,
including ground-water pH, ground-water
temperature, and the presence of-other com-
pounds in the subsurface environment. Table
2 provides additional information on attenua-
tion processes.
d. Exposure Pathways
A.complete exposure pathway usually con-
sists of four elements: 1) a source and mecha-
nism of chemical release, 2) a retention or
transport medium (in this case, ground
water), 3) a point of potential human contact
with the contaminated medium (often referred
to as the exposure point), and 4) an exposure
route (e.g., ingestion). Residents who live near
7A-9
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Protecting Ground Water—Assessing Risk
Table 2:
Examples of Attenuation Processes
Biological degradation: Decomposition of a substance into more elementary compounds by action
of microorganisms such as bacteria. Sullivan 1993 Environmental Regulatory Glossary, 6th Ed
Government Institutes. v *„ - >
Bio-uptake: The uptake and (at least temporary) storage of a chemical by an exposed organism The
chemical can be retained in its original form and/or modified by enzymatic and non-enzymatic reac-
tions in the body. Typically, the concentrations of the substance in the organism exceed the concentra-
tions in the environment since the organism will store die substance aridjiot excrete it Sullivan 1993,
Environmental Regulatory Glossary, 6th Ed. Government Institutes.' „ ^
Filtration: Physical process whereby solid parades and large'dissolved^molecules suspended in a
fluid are entrapped or.removed by the pore spaces of the soil"and aquifer media Bouldmg, R 1995 ,
Soil, Vadose Zone, and Ground-Water Contamination' Assessment, Prevention, and Remediation ^ <
Hydrolysis: A chemical process of decomposition in which the elements of water react with another
substance to yield one or more entirely new substances. This transfcjrmation.p^rocess changes the chem-
ical structure of the substance. Sullivan 1993 Environmental .Regulatory, Glossary, 6th Ed Government
Institutes. • ... ... ' A M.& ""' »T/?% " * ••• »' >
v S •"•! * -;
Oxidation/Reduction (Redox) reactions: Involve a transfer of electrons arid, dierefore, a change in
the oxidation state of elements. The chemical properties for elements can change substantially with
changes in the oxidation state. U S EPA 1991 Site Characterization for Subsurface Remediation
Precipitation: Chemical or physical change whereby a contaminant moves from a dissolved form in
a solution to a solid or insoluble form. It reduces die mobility of consutuents^such as metals. XJnbke
sorption, precipitation is not generally reversible. Bouldmg, R. 1995. Son, Vadose Zanef and Ground-
Water Contamination: Assessment, Prevention, and. Remediation. "T , ~
' V "
Sorption: The ability of a chemical to partition between thejliquid and solid phase by determining t
its affinity for adhering to other solids in the system^such as soils or sediments. The amount of chemi-
cal that "sorbs" to solids is dependent upon the characteristics of the chemical, the charactensucs of die
surrounding soils and sediments, and die quantity of the chemical Sorption generally is! reversible. *
Sorption often includes both adsorption and ion exchangev", l , ^ \,
a site might use ground water for their water
supply, and thus, the exposure point would be
a well. Exposure routes typical of residential
use of contaminated ground water include
direct ingestion through drinking water, der-
mal contact while bathing, and inhalation of
VOCs during showering or from other house-
hold water uses (e.g., dishwashers).
Another potential pathway of concern is
exposure to ground-water constituents from
the intrusion of vapors of VOCs and SVOCs
through the basements and concrete slabs
beneath houses. This pathway is character-
ized by the vapors seeping into households •
through the cracks and holes in basements
and concrete slabs. In some cases, concentra-
tions of constituents can reach levels, that pre-
sent chronic health.hazards. Factors .that can
contribute to the potential for vapor intrusion
include the types of constituents present in
the ground water, the presence of pavement
or frozen surface soils (which result in higher
subsurface pressure gradients and greater
transport), and the presence of subsurface
7A-10
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Protecting Ground Water—Assessing Risk
gases such as methane that affect the rate of
transport of other constituents. Because of the
complexity of this pathway and the evolving
science regarding this pathway, IWEM focuses
on the risks and pathways associated with
residential exposures to contaminated ground
water. If exposure through this route is likely,
the user might consider Tier 3 modeling to
assess this pathway EPA is planning to issue a
reference document regarding the vapor
intrusion pathway in the near future.
e.
Dose Calculation
The final element of the exposure assess-
ment is the dose calculation. The dose to a
receptor is a function of the concentration at
the .exposure point (i.-e, the well) and the
intake rate by .the receptor. The concentration
at the exposure point is based on the release
from the source and the fate and transport of
the constituent. The intake rate is .dependent
on the exposure route, the frequency ofexpo-
. sure, and the duration of exposure.
EPA produced the Exposure Factors
Handbook (U.S. EPA, 1997a) as a reference for
providing a consistent set of exposure factors
to calculate the dose. This reference is avail-
able from EPA's National Center for
Environmental Assessment Web site
. The purpose of the
handbook is to summarize data on human
behaviors and physical characteristics (e.g.,
body weight) that affect exposure to environ-
mental contaminants and recommend values
to use for these factors. The result of a dose
calculation is expressed as a contaminant con-
centration per unit body weight per unit time
that can then be used as the output of the
exposure assessment for the risk characteriza-
tion phase of .the analysis.
3. Toxidty Assessment
A toxicity assessment weighs available evi-
dence regarding the potential for particular
contaminants to cause adverse effects in
exposed individuals, and where possible, pro-
vides an estimate of the increased likelihood
and severity of adverse effects as a result of
exposure to a contaminant. IWEM uses two
different toxicity measures—maximum conta-
minant levels (MCLs) and health-based num-
bers (HBNs). Each of these measures is based
on toxicity values reflecting a cancer or non-
cancer effect. Toxicity data are based on
human epidemiologic data, animal data, or
other supporting studies (e.g., laboratory
studies). In general, data can be used to char-
acterize the potential adverse effect of a con-
stituent as^either carcinogenic or
non-carcinogenic. For the carcinogenic effect,
EPA generally assumes there is a non-thresh-
old effect and estimates a risk per unit dose.
For the noncarcinogenic effect, EPA generally
assumes there is a threshold below which no
adverse effects occur. The toxicity values used
in IWEM include:
• Oral cancer slope factors (CSFo) for
oral exposure to carcinogenic conta-
minants.
• Reference doses (RfD) for oral expo-
sure to contaminants that cause non-
cancer health effects.
• Inhalation cancer slope factors (CSFi)
. derived from Unit Risk Factors
(URFs) for inhalation exposure to car-
cinogenic contaminants. ' •
• Reference concentrations (RfC) for
inhalation exposure to contaminants
that cause noncancer health effects.
EPA defines the cancer slope factor (CSF)
as, "an upper bound, approximating a 95 per-
cent confidence limit, on the increased cancer
risk from a lifetime exposure to an agent [con-
taminant]." Because the CSF is an upper
bound estimate of increased risk, EPA is rea-
sonably confident that the "true risk" will not
exceed the risk estimate derived using the CSF
and that the "true risk" is likely to be less than
7A-11
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Protecting Ground Water—Assessing Risk
predicted. CSFs are expressed in units of pro-
portion (of a population) affected per mil-
ligram/kilogram-day (mg/kg-day). For
noncancer health effects, the RfD and the RfC
are used as health benchmarks for ingestion
and inhalation exposures, respectively. RfDs
and RfCs are estimates of daily oral exposure
or of continuous inhalation exposure, respec-
tively, that are likely to be without an appre-
ciable risk of adverse effects in the general
population, including sensitive individuals,
over a lifetime. The methodology used to
develop RfDs and RfCs is expected to have an
uncertainty spanning an order of magnitude.
a. Maximum Contaminant Levels
(MCLs)
MCLs are maximum permissible contami-
nant concentrations allowed in public drink-
ing water and are established under the Safe
Drinking Water Act. For each constituent to
be regulated, EPA first sets a Maximum
Contaminant Level Goal (MCLG) as a level
that protects against health risks. The MCL
for each contaminant is then set as close to
its MCLG as possible. In developing MCLs,
EPA considers not only the health effects of
the constituents, but also additional factors,
such as the cost of treatment, available ana-
lytical and treatment technologies. Table 3
lists the 57 constituents that have MCLs that
are incorporated in IWEM.
b. Health-based Numbers (HBNs).
The parameters that describe a chemical's
toxicity and a receptor's exposure to the chem-
ical are considered in calculation of the
HBN(s) of that chemical. HBNs are the maxi-
mum contaminant concentrations in ground
water that are not expected to cause adverse
noncancer health effects in the general popula-
tion (including sensitive subgroups) or that
will not result in an additional incidence of
cancer in more than approximately one in one
million individuals exposed to the contami-
nant. Lower concentrations of the contami-
nant are not likely to cause adverse health
effects. Exceptions might occur, howeyer, in
individuals exposed to multiple contaminants
that produce the same health effect. Similarly,
a higher incidence of cancer among sensitive
subgroups, highly exposed subpopulations, or
populations exposed to more than one cancer-
causing contaminant might be expected. As
noted previously, the exposure factors used to
calculate HBNs are described in the Exposure
Factors Handbook (U.S. EPA, 1997a).
4. Risk Characterization
Risk characterization is the integration of
the exposure assessment and the toxicity
assessment to generate qualitative and quan-
titative expressions of risk. For carcinogens,
the target risk level used in IWEM to; calcu-
late the HBNs is 1 x 10"6. A risk of 1 x 10*
describes an increased chance of one'in a
million of a person developing cancer over a
lifetime, due to chronic exposure to a,specific
chemical. The target hazard quotient used to
calculate the HBNs for noncarcinogens is 1.
A hazard quotient of 1 indicates that the esti-
mated dose is equal to the RfD (the level
below which no adverse effect is expected).
An HQ of 1, therefore, is frequently EPA's
threshold of concern for noncancer effects.
These targets are. used to calculate unique
HBNs for each constituent of concern and
each exposure route of concern (i.e., iinges-
tion or inhalation).
Usually, doses less than the RfD (HQ = 1)
are not likely to be associated with adverse
health effects and, therefore, are less likely to
be of regulatory concern. As the frequency or
magnitude of the exposures exceeding the
RfD increase (HQ > 1), the probability of
adverse effects in a human population
increases. However, it should not be categori-
cally concluded that all doses below the RfD
7A-12
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Protecting Ground Water—Assessing Ri
Table 3.
List of Constituents in 1WEM with Maximum Contaminant Levels (MCLs)
(States can have more stringent standards than federal MCLs.)
; Organics with an MGLr
Benzene 0.005
Benzo[a]pyrene 0.0002
Bis(2-ethylhexyl)phthalate 0.006
Bromodichloromethane* 0.10
Butyl-4,6-dinitrophenol,2-sec-(Dinoseb) 0.007
Carbon tetrachloride 0.005
Chlordane 0.002
Chlorobenzene 0.1
Chlorodibromomethane* 0.10
Chloroform* 0.10
Dibromo-3-chloropropane 1,2-(DBCP) 0.0002
Dichlorobenzene 1,2- 0.6
Dichlorobenzene 1,4- 0.075
Dichloroethane 1,2- 0.005
Dichloroethylene cis-1,2- 0.0"7
Dichloroethylene trans-1,2- 0.1
Dichloroethylene l,l-(Vinylidene chloride) 0.007
Dichlorophenoxyacetic acid 2,4- (2,4-D) 0.07
Dichloropropane 1,2- 0.005
Endrin 0.002
Ethylbenzene 0.7
Ethylene dibromide (1,2- Dibromoethane) 0.00005
HCH (Lindane) gamma- 0.0002
Heptachlor 0.0004
Heptachlor epoxide 0.0002
Hexachlorobenzene 0.001
Hexachlorocyclopentadiene 0.05
Methoxychlor 0.04
Methylene chloride (Dichloromethane) 0.005
Pentachlorophenol 0.001
Polychlorinated biphenyls (PCBs) 0.0005
Styrene 0.1
TCD Dioxin 2,3,7,8- 0.00000003
Tetrachloroethylene 0.005
Toluene 1
Toxaphene (chlorinated camphenes) 0.003
Tribromomethane (Bromoform)* 0.10
Trichferobenzene 1,2,4- 0.07
Trichloroethane 1,1,1- 0.2
Trichloroethane 1,1,2- 0.005
Trichloroethylene (1,1,2-Trichloroethylene) 0.005
2,4,5-TP (Silvex) 0.05
Vinyl chloride 0.002
Xylenes 10
Antimony
Arsenic**
Barium
Beryllium
Cadmium
Chromium
(total used for Cr III and Cr VI)
0.006
0.05
2.0
0.004
0.005
0.1
Copper***
Fluoride
Lead***
Mercury (inorganic)-
Selenium
Thallium
1.3
4.0
0.015
0.002
0.05
0.002
For list of current MCLs, visit:
* Listed as Total Trihalomethanes (TTHMs), constituents do not have individually listed MCLs.
** Arsenic standard will be lowered to 0.01 mg/L by 2006.
**-* Value is drinking water "action level" as specified by 40 CFR 141.32(e) (13) and (14).
7A-13
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Protecting Ground Water—Assessing Risk
are "acceptable" (or will be risk-free) and that
all doses in excess of the RfD are "unaccept-
able" (or will result in adverse effects). For
1WEM, the output from the risk characteriza-
tion helps determine with 90 percent proba-
bility (i.e., with a confidence diat for 90
percent of the realizations) whether or not a
design system is protective (i.e., has a cancer
risk of < 1 x 10'6, non-cancer hazard quotient
of < 1.0). IWEM does not address the cumu-
lative risk due to simultaneous exposure to
multiple constituents. The results of the risk
assessment might encourage the user to con-
duct a more site-specific analysis, or consider
opportunities for waste minimization or pol-
lution prevention.
II. The IWEM
Ground-Water
Risk Evaluation
This section takes the principles of risk
assessment described in Part I and applies
them to evaluating industrial waste manage-
ment unit liner designs. This is accomplished
using IWEM and a three-tiered ground-water
modeling approach to make recommenda-
tions regarding the liner design systems that
should be considered for a potential unit, if a
liner design system is considered necessary.
The tiered approach was chosen to provide
facility managers, the public, and state regu-
lators flexibility in assessing the appropriate-
ness of particular WMU designs as the user
moves from a national assessment to an
assessment using site-specific parameters.
The three tiers allow for three possible
approaches. The first approach is a quick
screening tool, a set of lookup tables, which
provides conservative national criteria. While
this approach, labeled Tier 1, does not take
into account site- (or even state-) specific con-
ditions, it does provide a rapid and easy
screening. If the use of Tier 1 provides an
agreeable assessment, the conservative nature
of the model can be relied upon, and the
additional resources required for further
analysis can be avoided. Of course, where
there is concern with the results from Tier 1,
a more precise assessment of risk at the
planned unit location should be conducted.
The second approach is to try and accommo-
date many of the most important site-specific
factors in a simplified form, useable by indus-
try, state, and environmental representatives.
This model, labeled Tier 2, is available as part
of this Guide, and is a major new step in
moving EPA guidance away from national,
"one size fits all" approaches. Third, a site-
specific risk analysis can be conducted. This
approach should provide the most precise
assessment of the risks posed by the planned
unit. Such an analysis, labeled Tier 3,';should
be conducted by experts in ground-water
modeling, and can require significant;
resources. This Guide identifies the benefits
and sources for selecting site-specific models,
but does not provide such models as part of
this Guide. In many cases, corporations will
go directly to conducting the more exacting
Tier 3 analysis, which EPA believes is accept-
able under the Guide. There is, however, still
a need for the Tier 2 tool. State and environ-
mental representatives might have limited
resources to conduct or examine a Tier 3
assessment; Tier 2 can provide a point of
comparison with the results of the Tier 3
analysis, narrow the technical discussion to
those factors which are different in the mod-
els, and form a basis for a more informed dia-
logue on the reasonableness of the differences.
IWEM is designed to address Tier JL and
Tier 2 evaluations. Both tiers of the tool con-
sider all portions of the risk assessment
process (i.e., problem formulation, exposure
assessment, toxicity assessment, and risk
characterization) to generate results that vary
from a national-level screening evaluation to
7A-14
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Protecting Ground Water—Assessing Risk
a site-specific assessment. The Tier 3 evalua-
tion is a complex, site-specific hydrogeologic
investigation that would be performed with
other models such as those listed at the end
of this chapter. Those models could be used
to evaluate hydrogeological complexities that
are not addressed by IWEM. Brief outlines of
the three tiers follow.
A Tier 1 evaluation involves comparing the
expected leachate concentrations of wastes
being assessed against a set of pre-calculated
maximum recommended leachate concentra-
tions (or Leachate Concentration Threshold
Values—LCTVs). The Tier 1 LCTVs are
nationwide, ground-water fate and transport
modeling results from EPA's Composite Model
for Leachate Migration with Transformation
Products (EPACMTP). EPACMTP simulates
the fate and transport of leachate infiltrating
from the bottom of a WMU and predicts con-
centrations of those contaminants in a well. In
making these predictions, the model quantita-
tively accounts for many complex processes
that dilute and attenuate the concentrations of
waste constituents as they move through the
subsurface to the well. The results that are
generated show whether a liner system is con-
sidered necessary, and if so which liner sys-
tems will be protective for the constituents of
concern. Tier 1 results are designed to be pro-
tective with 90 percent certainty at a IxlO6
risk level for carcinogens or a noncancer haz-
ard quotient of < 1.0.
The Tier 2 evaluation incorporates a limit-
ed number of site-specific parameters to help
provide recommendations about which liner
system (if any is considered necessary) is pro-
tective for constituents of concern in settings
that are more reflective of your site. IWEM is
designed to facilitate site-specific simulations
without requiring the user to have any previ-
ous ground-water modeling experience. As
with any ground-water risk evaluation, how-
ever, the user is advised to discuss the results
of the Tier 2 evaluation with the appropriate
state regulatory agency before selecting a liner
design for a new WMU.
If the Tier 1 and Tier 2 modeling do not
adequately simulate conditions at a proposed
site because the hydrogeology of the site is
complex, or because the user believes Tier 2
does not adequately address a particular site-
specific parameter, the user is advised to con-
sider a more in-depth, site-specific risk
assessment. This Tier 3 assessment involves a
more detailed, site-specific ground-water fate
and transport analysis. The user should con-
sult with state officials and appropriate trade
associations to solicit recommendations for
approaches for the analysis.
The remainder of this section discusses in
greater detail how to use IWEM to perform a
Tier 1 or Tier 2 evaluation. In addition, this
section presents information concerning the
use of Tier 3 models.
A. The Industrial Waste
Management Evaluation
IVIodel (IWEM)
The IWEM is the ground-water modeling
component of the Guide for Industrial Waste
Management, used for recommending appro-
priate liner system designs, where they are
considered necessary, for the management of
KCK& Subtitle D industrial waste. IWEM
compares the expected leachate concentration
(entered by the user) for each waste con-
stituent with a protective level calculated by a
ground-water fate and transport model to
determine whether a liner system is needed.
When IWEM determines a liner system is
necessary, it then evaluates two standard liner
types (i.e., single clay-liner and composite
liner). This section discusses components of
the tool and important concepts whose under-
standing is necessary for its effective use. The
user can refer to the User's Guide for the '
7A-15
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Protecting Ground Water—Assessing Risk
Industrial Waste Management Evaluation Model
(U.S. EPA, 2002b) for information necessary
to perform Tier 1 and Tier 2 analyses, and the
Industrial Waste Management Evaluation Model
Technical Background Document (U.S. EPA,
2002a), for more information on the use and
development of IWEM.
7. Leachate Concentrations
The first step in determining a protective
waste management unit design is to identify
the expected constituents in the waste and
expected leachate concentrations from the
waste. In order to assess ground-water risks
using either the Tier 1 or Tier 2 evaluations
provided in IWEM, the expected leachate
concentration for each individual constituent
of interest must be entered into the model.
See Chapter 2—Characterizing Wastes, for a
detailed discussion of the various approaches
available to use in evaluating expected
leachate concentrations.
2. Models Associated with IWEM
One of the highlights of IWEM is its abili-
ty to simulate the fate and transport of waste
constituents at a WMU with a small number
of site-specific inputs. To accomplish this
task, IWEM incorporates the outputs of three
other models, specifically EPACMTP, MINTE-
QA2, and HELP This section discusses these
three models.
a. EPACMTP
EPA's Composite Model for Leachate
Migration with Transformation Products
(EPACMTP) is the backbone of IWEM.
EPACMTP is designed to simulate subsurface
fate and transport of contaminants leaching
from the bottom of a WMU and predict con-
centrations of those contaminants in a down-
gradient well. In making these predictions,
the model accounts for many complex
processes that occur as waste constituents
and their transformation products move to
and through ground water. As leachate carry-
ing waste constituents migrates through the
unsaturated zone to the water table, attenua-
tion processes, such, as adsorption and degra-
dation, reduce constituent concentrations.
Ground-water transport in the saturated zone
further reduces leachate concentrations
through dilution and attenuation. The con-
centration of constituents arriving at a well,
therefore, is lower than that in the leachate
released from a WMU. i
In the unsaturated zone, the model simu-
lates one-dimensional vertical migration with
steady infiltration of constituents from the
WMU. In the saturated zone, EPACMTP sim-
ulates three-dimensional plume-movement
(i.e., horizontal as well as transverse and ver-
tical spreading of a contaminant plume). The
model considers not only the subsurface fate
and transport of constituents, but also the
formation and the fate and transport of trans-
formation (daughter and granddaughter)
products. The model also can simulate the
fate and transport of metals, taking into
account geochemical influences on the
mobility of metals.
b.
MINTEQA2
In the subsurface, metal contaminants can
undergo reactions with other substances in
the ground water and with the solid aquifer
or soil matrix material. Reactions in which
the metal is bound to the solid matrix are
referred to as sorption reactions, and the
metal bound to the solid is said to be sorbed.
During contaminant transport, sorption to
the solid matrix results in retardation (slower
movement) of the contaminant front.
Transport models such as EPACMTP incorpo-
rate a retardation factor to account for sorp-
tion processes. :
7A-16
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Protecting Ground Water—Assessing Risk
The actual geochemical processes that con-
trol the sorption of metals can be quite com-
plex, and are influenced by factors such as
pH, the type and concentration of the metal
in the leachate plume, the presence and con-
centrations of other constituents in the
leachate plume, and other factors. The
EPACMTP model is not capable of simulating
all these processes in detail. Another model,
MINTEQA25, is used to determine a sorption
coefficient for each of the metals species. For
IWEM, distributions of variables (e.g., leach-
able organic matter, pH) were used to gener-
ate a distribution of isotherms for each metal
species. EPACMTP, in turn, samples from
these calculated sorption coefficients and uses
the selected isotherm as a modeling input to
account for the effects of nationwide or
aquifer-specific ground-water and leachate
geochemistry on the sorption and mobility of
metals constituents.
c
HELP
The Hydrologic Evaluation of Landfill
Performance (HELP) model is a quasi-two-
dimensional hydrologic model for computing
water balances of landfills, cover systems, and
other solid waste management facilities. The
primary purpose of the model is to assist in
the comparison of design alternatives. HELP
uses weather, soil, and design data to com-
pute a water balance for landfill systems
accounting for the effects of surface storage;
snowmelt; runoff; infiltration; evapotranspira-
tion; vegetative growth; soil moisture storage;
lateral subsurface drainage; leachate recircula-
tion; unsaturated vertical drainage; and leak-
age through soil, geomembrane, or composite
liners. The HELP model can simulate landfill
systems consisting of various combinations of
vegetation, cover soils, waste cells, lateral
drain layers, low permeability barrier soils,
and synthetic geomembrane liners. For fur-
ther information on the HELP model, visit:
.
For the application of HELP to IWEM, an
existing database of infiltration and recharge
rates was used for 97 climate stations in the
lower 48 contiguous states. Five climate sta-
tions (located in Alaska, Hawaii, and Puerto
Rico) were added to ensure coverage
throughout all of the United States. These cli-
matic data were then used along with data on
the soil type and WMU design characteristics,
to calculate a water balance for each applica-
ble liner design as a function of the amount
of precipitation that reaches the surface of the
unit, minus the amount of runoff and evapo-
transpiration. The HELP model then comput-
ed the net amount of water that infiltrates
through the surface of the unit (accounting
for recharge), the waste, and the unit's bottom
layer (for unsaturated soil and clay liner sce-
narios only), based on the initial moisture
content and the hydraulic conductivity of
each layer.
Although data were collected for all 102
sites, these data were only used for the
unlined landfills, waste piles, and land appli-
cation units. For the clay liner scenarios
(landfills and waste piles only), EPA grouped
sites and ran the HELP model only for a sub-
set of the facilities that were representative of
the ranges of precipitation, evaporation, and
soil type. The grouping is discussed further in
the IWEM Technical Background Document
(U.S. EPA, 2002a).
In addition to climate factors and the par-
ticular unit design, the infiltration rates calcu-
lated by HELP are affected by the landfill
cover design, the permeability of the waste
material in waste piles, and the soil type of
the land application unit. For every climate
station and WMU design, multiple HELP
infiltration rates are calculated. In Tier 1, for
a selected WMU type and design, the
EPACMTP Monte Carlo modeling process
was used to randomly select from among the
HELP-derived infiltration and recharge data.
MINTEQA2 is a geochemical equilibrium speciation model for computing equilibria among the dis-
solved, absorbed, solid, and gas phases in dilute aqueous solution.
7A-17
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Protecting Ground Water—Assessing Risk
This process captured both the nationwide
variation in climate conditions and variations
in soil type. In Tier 2, the WMU location is a
required user input, and the climate factors
used in HELP are fixed. However, in Tier 2,
the Monte Carlo process is still used to
account for local variability in the soil type,
landfill cover design, and permeability of
waste placed in waste piles.
3. Important Concepts for Use
oflWEM
Several important concepts are critical to
understanding how IWEM functions. These
concepts include 90th percentile exposure
concentration, dilution and attenuations fac-
tors (DAFs), reference ground-water concen-
trations (RGCs), leachate concentration
threshold values (LCTVs), and units designs.
a. 90th Percentile Exposure
Concentration
The 90th percentile exposure concentra-
tion was chosen to represent the estimated
constituent concentration at a well for a
given leachate concentration. The 90th per-
centile exposure concentration was selected
because this concentration is protective for
90 percent of the model simulations con-
ducted for a Tier 1 or Tier 2 analysis. In Tier
1, the 90th percentile concentration is used
to calculate a DAF, which is then used to gen-
erate a leachate concentration threshold value
(LCTV). In Tier 2, the 90th percentile con-
centration is directly compared with a refer-
ence ground-water concentration to
determine whether a liner system is neces-
sary, and if so whether the particular liner
design is protective for a site.
The 90th percentile exposure concentra-
tion is determined by running EPACMTP in a
Monte Carlo mode for 10,000 realizations.
For each realization, EPACMTP calculates a
maximum average concentration at a well,
depending on the exposure duration of the
reference ground-water concentration (RGC)
of interest. For example, IWEM assumes a
30-year exposure duration for carcinogens,
and therefore, the maximum average concen-
tration is the highest 30-year average across
the modeling horizon. After calculating the
maximum average concentrations across the
10,000 realizations, the concentrations ,are
arrayed from lowest to highest and the 90th
percentile of this distribution is selected as
the constituent concentration for IWEM.
Once the 90th percentile exposure con-
centration is determined, it is used in-one of
two ways. For both the Tier 1 analysis and
the Tier 2 analysis, the 90th percentile expo-
sure concentration is compared with the
expected waste leachate concentration to
generate a DAE This calculation is discussed
further in the following section. For Tier 2,
the 90th percentile exposure concentration is
the concentration of interest for the analysis.
The 90th percentile exposure concentration
can be directly compared with the reference
ground-water concentration to assist in waste
management decision-making.
b. Dilution and Attenuation Factors
DAFs represent the expected reduction in
waste constituent concentration resulting
from fate and transport in the subsurface. A
DAF is defined as the ratio of the constituent
concentration in the waste leachate to the
concentration at the well, or:
CL
DAF = :
cw
where: DAF is the dilution and attenua-
tion factor;
CL is the leachate concentration
(mg/L); and ;
Cw is the ground-water well con-
centration (mg/L).
7A-18
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Protecting Ground Water—Assessing Risk
The magnitude of a DAF reflects the com-
bined effect of all dilution and attenuation
processes that occur in the unsaturated and
saturated zones. The lowest possible value of
a DAF is one. A DAF of 1 means that there is
no dilution or attenuation at all; the concen-
tration at a well is the same as that in the
waste leachate. High DAF values, on the
other hand, correspond to a high degree of
dilution and attenuation. This means that the
expected concentration at the well will be
much lower than the concentration in the
leachate. For any specific site, the DAF
depends on the interaction of waste con-
stituent characteristics (e.g., whether or not
the constituent degrades or sorbs), site-specif-
ic factors (e.g., depth to ground water, hydro-
geology), and physical and chemical
processes in the subsurface environment. In
addition, the DAF calculation does not take
into account when the exposure occurs, as
long as it is within a 10,000-year time-frame
following the initial release of leachate. Thus,
if two constituents have different mobility, the
first might reach the well in 10 years, while
the second constituent might not reach the
well for several hundred years. EPACMTP,
however, can calculate the same or very simi-
lar DAF values for both constituents.
For the Tier 1 analysis in IWEM, DAFs are
based on the 90th percentile exposure con-
centration. EPACMTP was implemented by
randomly selecting one of the settings from
the WMU- database and assigning a unit
leachate concentration to each site until
10,000 runs had been conducted for a WMU.
The resulting 10,000 maximum well concen-
trations based on the averaging period associ-
ated withithe exposure duration of interest
(i.e., 1-year, 7-years, 30-years) were then
arrayed from lowest to highest. The 90th per-
centile concentration of this distribution is
then used as the concentration in the ground-
water welL.(Cw) for calculating the DAF. The
DAF is similarly calculated for the Tier 2, but
because the site-specific leachate concentra-
tion is used in the EPACMTP model runs, the
90th percentile exposure concentration can
be compared directly to the RGC.
c Reference Ground-Water
Concentration (RGC)
As used in this Guide and by IWEM, a ref-
erence ground-water concentration (RGC) is
defined as a constituent concentration thresh-
old in a well that is protective of human
health. RGCs have been developed based on
maximum contaminant levels (MCLs) and
health-based-numbers (HBN). Each con-
stituent can have up to five RGCs: 1) based
on an MCL, 2) based on carcinogenic effects
from ingestion, 3) based on carcinogenic
effects from inhalation while showering, 4)
based on non-carcinogenic effects from inges-
tion, and 5) based on non-carcinogenic
effects from inhalation while showering.
The IWEMs database includes 226 con-
stituents with at least one RGC. Of the 226
constituents, 57 have MCLs (see Table 3),
212 have ground-water ingestion HBNs, 139
have inhalation HBNs, and 57 have both an
MCL and HBN. The HBNs were developed
using standard EPA exposure assumptions for
residential receptors. For carcinogens, IWEM
used a target risk level equal to the probabili-
ty that there might be one increased cancer
case per one million exposed people '(com-
monly referred to as a IxlO'6 cancer risk).
The target hazard quotient used to calculate
the HBNs for noncarcinogens was 1 (unit-
less). A hazard quotient of 1 indicates that
the estimated dose is equal to the oral refer-
ence dose (RfD) or inhalation reference con-
centration (RfC). These targets were used to
calculate unique HBNs for each constituent of
concern and each exposure route of concern
(ingestion or inhalation). For further informa-
tion on the derivation of the IWEM RGCs,
see the Industrial Waste Management
Evaluation Model Technical Background
7A-19
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Protecting Ground Water—Assessing Risk
Document (U.S. EPA, 2002a). Users also can
add new constituents and RGCs can vary
depending on the protective goal. For exam-
ple, states can impose more stringent drink-
ing water standards than federal MCLs.6 To
keep the software developed for this Guide
up-to-date, and to accommodate concerns at
levels different from the current RGCs, the
RGC values in the IWEM software tool can
be modified by the user of the software.
of. Leachate Concentration Threshold
Values (LCTVs)
The purpose of the Tier 1 analysis in
IWEM is to determine whether a liner system
is needed, and if so, to recommend liner sys-
tem designs or determine the appropriateness
of land application with minimal site-specific
data. These recommendations are based on
LCTVs that were calculated to be protective
for each waste constituent in a unit. These
LCTVs are the maximum leachate concentra-
tions for which water in a well is not likely to
exceed the corresponding RGC. The LCTV
for each constituent accounts for dilution and
attenuation in the unsaturated and saturated
zones prior to reaching a well. An LCTV has
been generated for a no liner/in situ soils sce-
nario and for two standard liner types (i.e.,
single clay liner and composite liner) and
each RGC developed for a constituent.
The LCTV for a specific constituent is the
product of the RGC and the DAF:
LCTV = DAF * MCL
or LCTV = DAF * HBN
Where: LCTV is the leachate concentra-
tion threshold value
DAF is the dilution and attenua-
tion factor
MCL is the maximum concentra-
tion level
HBN is the health-based number
The evaluation of whether a liner system is
needed and subsequent liner system design
recommendations is determined by compar-
ing the expected waste constituent leachate
concentrations to the corresponding calculat-
ed LCTVs. LCTVs are calculated for all unit
types (i.e., landfills, waste piles, surface
impoundments, land application units) by
type of design (i.e., no liner/in situ soils, sin-
gle liner, or composite liner).7 The Tier 1
evaluation is generally the most protective
and calculates LCTVs using data collected on
WMUs throughout the United States.8' LCTVs
used in Tier 1 are designed to be protective
to a level of 1x10'6 for carcinogens or a non-
cancer hazard quotient of < 1.0 with a 90
percent certainty considering the range of
variability associated with the waste sites
across the United States. LCTVs from the Tier
1 analysis are generally applicable to sites
across the country; users can determine
whether a specific liner design for a WMU is
protective by comparing expected leachate
concentrations for constituents in their waste
with the LCTVs for each liner design.
The Tier 2 analysis differs from the Tier 1
analysis in that IWEM calculates a site-specif-
ic DAF in Tier 2. This allows the model to
calculate a site-specific 90th percentile expo-
sure concentration that can be compared
with an RGC to determine if a liner system is
needed and to recommend the appropriate
liner system if necessary. The additional cal-
culation of an LCTV is not necessary. IWEM
continues to perform the calculation, howev-
er, to help users determine whether waste
minimization might be appropriate to :meet a
specific design. For example, a facility might
7A-20
6 For example, a state can make secondary MCLs mandatory, which are not federally enforceable stan-
dards, or a state might use different exposure assumptions, which can result in a different HBN. In
addition, states can choose to use a different risk target than is used in this Guidance.
? LCTVs are influenced by liner designs because of different infiltration rates. :
" For additional information on the nationwide data used in the modeling, see the IWEM Technical
Background Document (U.S. EPA, 2002a). '.
-------
Protecting Ground Water—Assessing Risk
find it .more cost effective to reduce the con-
centration of constituents in its waste and
design a clay-lined landfill than to dispose of
the current waste in a composite landfill. The
LCTV calculated for the Tier 2 analysis is
based on the expected leachate concentration
for a specific site and site-specific data for
several sensitive parameters. Because the Tier
2 analysis includes site-specific considera-
tions, LCTVs from this analysis are not
applicable to other sites.
e. Determination of Liner Designs
The primary method of controlling the
release of waste constituents to the subsurface
is to install a low permeability liner at the
base of a, WMU. A liner generally consists of a
layer of clay or other material with a low
hydraulic conductivity that is used to prevent
or mitigate the flow of liquids from a WMU.
The type of liner that is appropriate for a spe-
cific WMU, however, is highly dependent
upon a number of location-specific character-
istics, such as climate and hydrogeology.
These characteristics are critical in determin-
ing the amount of liquid that migrates into
the subsurface from a.WMU and in predicting
the release of contaminants to ground water.
The IWEM software is intended to assist
the user in determining if a new industrial
waste management unit can rely on a no
liner/in situ soils design, or whether one of
the two recommended liners designs, single
clay liner or composite liner, should be used.
The no liner/in situ soils design (Figure 2a)
represents a WMU that relies upon location-
specific conditions, such as low permeability
native soils beneath the unit or low annual
precipitation rates to mitigate the release of
contaminants to groundwater. The single clay .
liner (Figure 2b) design represents a 3-foot
thick clay liner with a low hydraulic conduc-
tivity (IxlO'7 cm/sec) beneath a WMU. A
composite liner design (Figure 2c) consists of
a flexible membrane liner in contact with a
clay liner. In Tier 2, users also can evaluate
other liner designs by providing a site-specific
infiltration rate based on the liner design. For
land applications units, only the no liner/in
situ soils scenario is evaluated because liners
are not typically used at this type of facility.
To determine an appropriate design in Tier
1, IWEM compares expected leachate con-
centrations for all of the constituents in the
leachate to constituent-specific LCTVs and
then reports the minimum design system that
is protective for all constituents. If the expect-
ed leachate concentrations of all waste con-
stituents are lower than their respective no
liner/in situ soils LCTVs, the proposed WMU
does not need a liner to contain the waste.
On the other hand, if die Tier 1 screening
evaluation indicates a liner is recommended,
a user can verify this recommendation with a
follow-up Tier 2 (or possibly Tier 3) analysis ,
for at least those constituents whose expected
leachate concentrations exceed the Tier 1
LCTV values.
If the user proceeds to a Tier 2 analysis,
IWEM will evaluate the three standard
designs or it can evaluate a user-supplied
liner design. The user can supply a liner
design by providing a site-specific infiltration
rate that reflects the expected infiltration rate
through the user's liner system. In the Tier 2
analysis, IWEM conducts a location-adjusted
Monte Carlo analysis based on user inputs to
generate a 90th percentile exposure concen-
tration for the site. The 90th percentile expo-
sure concentration is then compared with the
RGC to determine whether a liner is consid-
ered necessary,, and where appropriate, rec-
ommend the design that is protective for each
constituent expected in the leachate. If the
Tier 2 analysis indicates that the no liner/in
situ soils scenario or the user-defined liner is
not protective, the user can proceed to a full
site-specific Tier 3 analysis.
7A-21
-------
Protecting Ground Water—Assessing Risk
Figure 2. Three Liner Scenarios Considered in the Tiered Modeling Approach for Industrial
Waste Guidelines :
Flexible
/ Membrane
Liner
a) No Liner/In Situ Soils Scenario
b) Single Liner Scenario
c) Composite Liner Scenario
B. Tier 1 Evaluations
In a Tier 1 evaluation, IWEM compares
the expected leachate concentration for each
constituent with the LCTVs calculated for
these constituents and determines a mini-
mum recommended design that is protective
for all waste constituents. The required
inputs are: the type of WMU the user wishes
to evaluate, the constituents of concern, and
the expected leachate concentrations of con-
stituents of concern. The results for each
constituent have been compiled for each unit
type and design and are available in the
IWEM Technical Background Document (U.S.
EPA, 2002a) and in the model on the CD-
ROM version of this Guide.
The tabulated results for Tier 1 of IWEM
have been generated by running the
EPACMTP for a wide range of conditions that
reflect the varying site conditions that can be
expected to occur at waste sites across the
United States. The process, which was used
to simulate varying site conditions, is known
as a Monte Carlo analysis. A Monte Carlo
analysis determines the statistical probability
or certainty that the release of leachate might
result in a ground-water concentration
exceeding regulatory or risk-based standards.
For the Tier 1 analysis, 10,000 realizations
of EPACMTP were run for each constituent,
WMU, and design combination to generate
distributions of maximum average exposure
concentrations for each constituent by WMU
and design. These distributions reflect the vari-
ability among industrial waste management
units across the United States. The 90th per-
centile concentration from this distribution was
then used to calculate a DAF for each con-
stituent by WMU and design. Each of these
DAFs was then combined with constituent-
specific RGCs to generate the LCTVs presented
About Monte Carlo Analysis
Monte Carlo analysis ^is.a computer-
based method of analysis'developed in
the 1940s that uses statistical sampling
techniques in obtaining a probabilistic
approximation to, the solution of a math-
" ematicat equation or model. The name
refers to the city on the French Riviera,
which is known for its gambling and _ „
other games of chance. Monte Carlo
analysis is increasingly used in risk
assessments because it allows the risk
, manager to make decisions based on a
statistical level of protection that reflects
the variability and/or uncertainty in risk
parameters or processes, rather,than
making decisions based on a single point
estimate of risk. For further information
on Monte Carlo analysis in risk assess-
ment, see EPA's Guiding Principles for
Monte Carlo Analysis: (U.S. EPA, 1997b).
7A-22
-------
Protecting Ground Water—Assessing Risk
in the IWEM software and in the tables includ-
ed in the technical background document.
The advantages of a Tier 1 screening evalu-
ation are that it is fast, and it does not require
site-specific information. The disadvantage of
the Tier 1 screening evaluation is that the
analysis does not use site-specific information
and might result in a design recommendation
that is more stringent than is needed for a
particular site. For instance, site-specific con-
ditions, such as low precipitation and a deep
unsaturated zone, might warrant a less strin-
gent design. Before implementing a Tier 1
recommendation, it is recommended that you
also perform a Tier 2 assessment for at least
those waste constituents for which Tier 1
indicates that a no liner design is not protec-
tive. The following sections provide addition-
al information on how to use the Tier I
lookup tables.
1. How Are the Tier 1 Lookup
Tables Used?
The Tier 1 tables provide an easy-to-use
tool to assist waste management decision-
making. Important benefits of the Tier 1
approach are that it requires minimum data
from the user and provides immediate guid-
ance on protective design scenarios. There are.
only three data requirements for the Tier I
analysis: WMU type, constituents- expected! inn
the waste leaefiate, amdi the expected leachate
concentration for each constituent in the
waste. The Tier 1 tables are able to provide
immediate guidance because EPACMTP simu-
lations for each constituent, WMU, and
design combinations were run previously for
a national-scale assessment to generate appro-
priate LCTVs for each combination. Because
the simulations represent a national-scale
assessment,, the LCTVs in the Tier 1 tables
represent levels in leachate that are protective
at most sites.
As noted previously in this chapter, one of
the first steps in a ground-water risk assess-
ment is to characterize the waste going into a
unit. Characterization of the waste includes
identifying the constituents expected in the
leachate and estimating leachate concentra-
tions for each of these constituents.
Identification.of constituents expected in
leachate can be based on process knowledge
or chemical analysis of the waste. Leachate
concentrations can be estimated using
process knowledge or an analytical leaching
test appropriate to the circumstances, such as
the Toxicity Characteristic Leaching
Procedure (TCLP). For more information on
identifying waste constituents, estimating
waste constituent leachate concentrations,
and selecting appropriate leaching tests, refer
to Chapter 2 — Characterizing Waste.
The following example illustrates the Tier
1 process for evaluating a proposed design
for an industrial landfill. The example
assumes the expected leachate concentration
for toluene is 1.6 mg/L and styrene is 1.0
Information Needed to
Use Tier 1 Lookup Tables
Waste management Landfill, surface,;/
unit types: impoundment,
', waste pile, or land
application unit.
Constituents
expected
in the leachate:
^ / S v
Leachate
^concentrations:
Constituent names
and/or CAS numbers.
Expected leachate
concentration of
each constituent or
concentration in
surface "impound-'
ments or waste to be
applied.
7A-23
-------
Protecting Ground Water—-Assessing Risk
mg/L. Both toluene and styrene have three
LCTVs: one based on an MCL, one based on
non-cancer ingestion, and one based on non-
cancer inhalation. Tables 4 and 5 provide
detailed summary information for the no
liner/in situ soils scenario for MCL-based
LCTVs and the HBN-based LCTVs, respec-
tively, that is similar to the information that
can be found in the actual look-up tables.
For the Tier 1 MCL-based analysis pre-
sented in Table 4, the results provide the
following information: constituent CAS
number, constituent name, constituent-spe-
cific MCL, user-provided leachate concen-
tration, constituent-specific DAF, the
constituent-specific LCTV, and whether the
specified design is protective at the target
risk level. To provide a recommendation as
to whether a specific design is protective or
not, IWEM compares the LCTV with the
leachate concentration to determine
whether the design is protective. In the
example presented in Table 4, the no
liner/in situ soils scenario is not protective
for styrene because the leachate concentra-
tion provided by the user (1.0 mg/L) is
greater than the Tier 1 LCTV (0.22 mg/L).
For toluene, the no liner/in situ soils sce-
nario is protective because the leachate con-
centration (1.6 mg/L) is less than the Tier 1
LCTV (2.2 mg/L).
For the health-based number (HBN)-based
results presented in Table 5, the detailed
results present similar information to that
presented for the MCL-based results. The dif-
ferences are that the HBN-resuks present the
constituent-specific HBN rather than the
MCL and include an additional column that
identifies the pathway and effect that -support
the development of the LCTV For the con-
trolling pathway and effect column, IWEM
would indicate whether the most protective
pathway is ingestion of drinking water (indi-
cated by ingestion) or inhalation during
showering (indicated by inhalation) and
whether the adverse effect is a cancer1 or non-
cancer effect. In this example, both styrene
and toluene have two HBN-based LCTVS:
one for ingestion non-cancer and one for
inhalation non-cancer. Only the results for
the controlling HBN exposure pathway and
effect are shown. In Table 5, only the Results
for the inhalation-during-showering pathway
for non-cancer effects are shown because this
is the most protective pathway (that is, the
LCTV for the inhalation-during-showing
pathway is lower than the LCTV for ingestion
of drinking water) for both of these con-
stituents. As shown in Table 5, comparison of
the leachate concentration of styrene (l.O
mg/L) and toluene (1.6 mg/L) to their respec-
tive LCTVs (8.0 mg/L and 2.9 mg/L) indi-
cates that the no liner/in situ soils design is
protective for the Tier 1 HBN-based L|CTVs.
Based on the results for the no liner/in situ
soils scenario, the user could proceed'to the
comparison of the expected leachate cloncen-
tration for styrene with the MCL-based LCTV
for a single clay liner to determine whether
the single clay liner design is protective. The
Table 4:
Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - No Liner/In situ Soils
CAS |*
100-42-5
108-88-3
- 'I ! . -! . '
Constituent MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) Protective?:
'.( - i i - : . ' ' :: I -i-
Styrene
Toluene
0.1
1.0
1.0
1.6
2.2 0.22 i No
2.2 2.2 Yes
7A-24
-------
Protecting Ground Water—Assessing Risk
Table 5:
Example of Tier 1 Summary Table for HBN-based LCTVs for Landfills.- No Liner/In situ Soils
*CAST:#:
' W<"$'-!-"~,
:' ; :G6hstitueiit
100-42-5 Styrene
108-88-3 ' Toluene
HBN-(mg/L),
3.6
1.3
•"> Leaehate ,, :_
Concentration
>, (mg/L) .
' 1.0
1.6
1 1 > • '.--,"
DAF "LCTV (nig/L^v
2.2 8.0 •
2.2 2
9
-:. Protective?
Yes '
'Yes
Controlling ; .
Pathway &
- 'Elkci ^: ;
Inhalation
Non-cancer
Inhalation
Non-cancer
user also can proceed to a Tier 2 or Tier 3
analysis to determine whether a more site-
specific approach might'indicate that the no
liner/in situ soils design is protective for the
site. Table 6 presents the Tier 1 results for the
single clay liner. As shown, the single clay
liner would not be protective for the MCL-
based analysis because the expected leachate
concentration for styrene (1.0 mg/L) exceeds
the LGTV for styrene (0.61 mg/L). Based on
these results, the user could.continue on to
evaluate whether a composite diner is protec-
tive for styrene.
Table 7 presents the results of the Tier 1
MCL-based analysis for a composite liner.9 A
comparison of the leachate concentration for
styrene (1.0 mg/L) to the MCL-based LCTV
(1000 mg/L) indicates that the composite
liner is the recommended liner based on a
Tier 1 analysis that will be protective for both
styrene and toluene.
2. What Do the Results Mean
and How Do I Interpret Them?
For the Tier 1 analysis,' IWEM evaluates
the no liner/in situ soils, single clay liner, and
Table 6:
Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Single Clay Liner
••^
-.-.;•-••«• - -
••CAB#.- "--:
- T; -" .
100-42-5
108-88-3
Constituent . MCL (mg/L) Leachate Concentration (mg/L) DAF LCTV (mg/L) , Protective? ..
Styrene 0.1
Toluene 1.0
1.0 6.1 0.61 • No
1.6 6.1 6.1 Yes
Table 7:
Example of Tier 1 Summary Table for MCL-based LCTVs for Landfills - Composite Liner
•••J! •---•• - '- ---• - - - •-
CAp# Constituent MCL (mg/L)
100-42-5 • Styrene 0.1
108-88-3 Toluene 1.0
Leachate Concentration (mg/L)
1.0
1.6
DAF LCTV (mg/L) ; . Protective? -v^'
5.4xl04 1000 Yes
2.9xl04 1000 . Yes
Table 7 also indicates the effect of the 1000 mg/L cap on the results. The LCTV results from multiply-
ing the RGC with the DAE In this example, the MCL for styrene (0.1 mg/L) multiplied by the unitless
DAF (5.4 x 104) would result in an LCTV of 5,400 mg/L, but because LCTVs are capped, the LCTV for
styrene in a composite liner is capped at 1,000 mg/L. See Chapter 6 of the Industrial Waste Management
Evaluation Model Technical Background Document (U.S. EPA, 2002a) for further information.
7A-25
-------
Protecting Ground Water—Assessing Risk
composite liner design scenarios, in that
order. Generally, if the expected leachate con-
centrations for all constituents are lower than
the no liner LCTVs, the proposed unit does
not need a liner to contain this waste. If any
expected constituent concentration is higher
than the no liner/in situ soils LCTV, a single
compacted clay liner or composite liner
would be recommended for containment of
the waste using the Tier 1 analysis. If any
expected concentration is higher than the
single clay liner LCTV, the recommendation
is at least a composite liner. If any expected
concentration is higher than the composite
liner LCTV, pollution prevention, treatment,
or additional controls should be considered,
or a Tier 2 or Tier 3 analysis can be conduct-
ed to consider site-specific factors before
making a final judgment. For waste streams
with multiple constituents, the most protec-
tive design that is recommended for any one
constituent is the overall recommendation. In
the example illustrated in Tables 4, 5, 6, and
7, the recommended design is a composite
liner because the expected leachate concen-
tration for styrene exceeds the no liner/in situ
soils and clay liner LCTVs in the MCL-based
analysis, but is lower than the composite
liner LCTV For the HBN-based analysis, a no
liner/in situ soils design would provide ade-
quate protection for the site because, as
shown in Table 5, the leachate concentrations
for styrene and toluene are lower than their
respective HBN-based LCTVs.
The interpretation for land application is
similar to the interpretation for landfills.
However, only the no liner/in situ soils sce-
nario is evaluated for land application
because these types of units generally do not
use liner systems. Thus, if all the waste
leachate concentrations are below the no
liner/in situ soils MCL-based and HBN-based
LCTVs in the Tier 1 lookup tables, land- '
applying waste might be appropriate for the
site. If the waste has one or more con-
stituents whose concentrations exceed a land
application threshold, the recommendation is
that land application might not be appropri-
ate. The model does not consider the other
design scenarios.
After conducting the Tier 1 evaluation,
users should consider the following steps:
• Perform additional evaluations.
The Tier 1 evaluation provides a con-
servative screening assessment whose
values are calculated to be protective
over a range of conditions and situa-
tions. Although a user could elect to
install a liner based on the Tifer 1
results, it is appropriate that a user
consider Tier 2 or Tier 3 evaluations
to confirm these recommendations.
• Consider pollution prevention,
recycling, or treatment. If YOU do-
not want to conduct s. Tier 2 ir Tier
3 analysis, and the waste has £ne or
more "problem" constituents that call
for a more stringent and costly design
system (or which make land applica-
tion inappropriate), you could con-
sider pollution prevention, recycling,
and treatment options for those con-
stituents. Options that previously
might have appeared economically
infeasible, might be worthwhile if
they can reduce the problem con-
stituent concentration to a level that
results in a different design recom-
mendation or would make land
application appropriate. Then,- after
implementing these measures, repeat
the Tier 1 evaluation. Based on the
results presented in Table 6, pollution
prevention, recycling, or treatment
measures could be used to reduce the
expected leachate concentration for
styrene below 0.61 mg/L so that a
single liner is recommended for the
unit. Consult Chapter 3—Integrating
7A-26
-------
Protecting Ground Water—Assessing Risk
Pollution Prevention, for ideas and
tools.
Implement recommendations. You
can design the unit based on the
design recommendations of the Tier
1 lookup tables without performing
further analysis or considering pollu-
tion prevention or recycling activities.
In the case of land application, a land
application system might be devel-
oped (after evaluating other factors) if
the lookup tables found no liner nec-
essary for all constituents. In either
case, it is recommended that you
consult the appropri-
1. How is a Tier 2 'Analysis
Performed?
Under Tier 2, the user can provide site-
specific information to refine the design rec-
ommendations. The Tier 2 analysis leads the
user through a series of data entry screens
and then runs EPACMTP to generate a design
recommendation based on the site-specific
information provided by the user. The user
can provide data related to the WMU, the
subsurface environment, infiltration rates,
physicochemical properties, and toxicity the
user can evaluate the three designs-discussed
above or provide data reflecting a site-specific
ate agency to ensure
compliance with
state regulations.
Figure 3 illustrates the
basic steps using the Tier 1
lookup tables to determine
an appropriate design for a
proposed waste manage-
ment unit or whether land
application is appropriate.
C. Tier 2
Evaluations
The Tier 2 evaluation is
designed to provide a
more accurate evaluation
than Tier 1 by allowing
the user to provide site-
specific data. In many
cases, a Tier 2 evaluation
might suggest a less strin-
gent and less costly design
than a Tier 1 evaluation
would recommend. This
section describes the
inputs for the analysis and
the process for determin-
ing a protective recom-
mendation.
Figure 3. Using Tier 1 Lookup Tables
Identify proposed WMU type.
Estimate waste leachate concentration for
all potential constituents expected to be
present in the waste.
YES
Compare expected leachate concentrations
to calculated LCTVs for all potential
constituents.
Will pollution preven-
tion, recycling, or treat-
ment be implemented to
reduce concentrations of
problem constituents?
Do you have
site-specific
data?
NO
Consider implement-
ing liner and/or land
application recom-
mendation, or obtain-
ing additional data for
a Tier 2 or Tier 3
analysis.
Consider a Tier 2 evaluation or
performing a comprehensive Tier
3 site-specific ground-water fate
and transport analysis.
7A-27
-------
Protecting Ground Water—Assessing Risk
liner design. As a result, a Tier 2 analysis
provides a protective design recommendation
intended only for use at the user's site, and is
not intended to be applied to other sites.
This section discusses the inputs that a user
can provide and the results from the analysis.
a. Tier 2 Inputs
In addition to die inputs required for the
Tier 1 analysis, a Tier 2 analysis allows users
to provide additional inputs that account for
attributes that are,specific to the user's site.
The Tier 2 inputs that are common to the
Tier 1 evaluation are:
• WMU type—waste pile, surface
impoundment, or land application
unit.
• Chemical constituents of concern
present in the WMU.
• Leachate concentration (in mg/L) of
each constituent.
If the user has already performed a Tier 1
analysis and continues to a Tier 2 analysis,
the Tier 1 inputs are carried forward to the
Tier 2 analysis. In the Tier 2 analysis, howev-
er, the user can change these data without
changing the Tier 1 data.
In addition to the Tier 1 inputs, the user
also provides values for additional parameters
including WMU area, WMU depth for land-
fills, ponding depth for surface impound-
ments, and die climate center in the IWEM
database that is nearest to the site. These
parameters can have a significant influence
on the LCTVs generated by the model and
also are relatively easy to determine. The user
also has the option to provide values for sev-
eral more parameters. Table 8 presents the
list of "required" and "optional" parameters.
Because site-specific data for all of the .
EPACMTP parameters might not be available,
the model contains default values for the
"optional" parameters that are used unless
the user provides site-specific data. The
default values are derived from a number of
sources, including a survey of industrial
waste management units, a hydrogeologic
database, water-balance modeling, and values
reported in the scientific literature. The selec-
tion of default values is explained in, the
IWEM Technical Background Document (U.S.
EPA, 2002a). If site-specific data areiavail-
able, they should be used to derive the most
appropriate design scenario for a particular
site.10
In addition to the above parameters, users
can also enter certain constituent specific
properties, as follows:
• Organic carbon distribution coeffi-
cient (KOC). A function of the nature
of a sorbent (the soil and its organic
carbon content) and the properties of
a chemical (the leachate constituent).
It is equal to the ratio of the: solid
and dissolved phase concentrations,
measured in milliliters per gram
(mL/g). The higher the value of the
distribution coefficient, the higher
the adsorbed-phase concentration,
meaning the constituent would be
less mobile. For metals, IWEM pro-
vides an option to enter a site-specif-
ic soil-water partition coefficient (Kd),
which overrides the MINTEQA2
default sorption isotherms.
• Degradation coefficient. The rate at
which constituents degrade or decay
within an aquifer due to biochemical
processes, such as hydrolysis or
biodegradation (measured in units of
I/year). The default decay rate in
IWEM represents degradation from
chemical hydrolysis only, since
biodegradation rates are strongly
influenced by site-specific factors. In
. Tier 2, a user can enter an overall
7A-28
10 A Tier 2 evaluation is not always 'kss conservative than a Tier 1. For example, if a site has a Very large
area, a very shallow water table, and/or the aquifer thickness is well below the national average, then
the Tier 2 evaluation results can be more stringent than the Tier 1 analysis results.
-------
Protecting Ground Water—Assessing Risk
Table 8.
Input Parameters for Tier 2
-Paifarneter i* Descrmtion : : « ::;; '; * Use in Model > Units ; * Applicable Re^uirM or 1
;.;X;vl:^--- ~*'- ;=--r- ^ ': -^ ------- •'•'":.':;- •-•---' --." : •""•:--- '•".•'•"-'-• -•-•"• WMU '. Optional- 1
"V --K--^r:--,!:- -;-i" .-.- - •;<;-•;:,,: - ..-•-.;:;.-.- .-•.•-. -.:, --„.--••- -.-.-.--" - ' - "- -••_-_^_t ^ ^ 1
WMU area
WMU location
Total waste
management unit
depth
Depth of waste .
management unit
below ground
surface
Surface
Impoundment
sediment layer
thickness
WMU operational
life
WMU infiltration
rate
Soil type
Distance to a well
Hydrogeological
setting
Area covered by the WMU
Geographic location of WMU in terms of
he nearest of 102 climate stations
Depth of the unit for landfills (average
thickness of waste in the landfill, not
counting the thickness of a liner below the
waste or the thickness of a final cover on
top of the waste) and surface'
mpoundments (depth of the free-standing
iquid in the impoundment, not counting
.he thickness of any accumulated sediment
ayer at the base of the impoundment)
Depth of the base of the unit below the
ground surface
Thickness of sediment at the base of
surface impoundment (discounting
thickness of engineered liner, if present)
Period of time WMU is in operation.
Rate at which leachate flows from the
bottom of a WMU (including any liner)
into unsaturated zone
Predominant soil type in the vicinity of
the WMU
The distance from a WMU to a
downgradient well.
Information on the hydrogeological setting
of the WMU
[b determine the area for
nfiltration of leachate
To determine local climatic
conditions that affect infiltration
and aquifer recharge
For landfills, used to determine
the landfill depletion rate. For
surface impoundments, used
as the hydraulic head to derive
.eakage
Used together with depth of the
water table to determine
distance leachate has to travel
through unsaturated zone to
reach ground water
Limits infiltration from unit.
IWEM assumes leachate
generation occurs over the same
period of time.
Affected by area's rainfall
intensity and design
performance. Users either input
infiltration rates directly or
allow IWEM to estimate values
based on the unit's geographic
location," liner design, cover
design and WMU type.
Uses site-specific soil data to
model leachate migration
through unsaturated zone and
determine regional recharge rat
To determine the horizontal
distance over which dilution
and attenuation occur.
Determines certain aquifer
characteristics (depth to water
table, saturated zone thickness,
saturated zone hydraulic
conductivity, ground-water
hydraulic gradient) when
complete information not
available
Square meters (m2)
Unitless
Meters (m)
Meters (m)
Meters (m)
Years
Meters per year
(m/yr)
sandy loam
silt loam
silty clay loam
Meters (m)
Varies
All
All
LF
SI
LF
SI
WP
SI
WP
SI
LAU
All
All
All
All
Required
Required
Required for
landfills and
surface
impoundments
Optional
Optional
Optional
Optional
Optional
Optional
Optional
1 For surface impoundments IWEM can use either the unit's geographic location or impoundment characteristics
(such as ponding depth, and thickness of sediment kyer) to estimate the infiltration rates.
7A-29
-------
Protecting Ground Water—Assessing Bisk
Table 8.
Input Parameters for Tier 2 (con't)
' 1 ' '. '-. -:': ; . '- ., - • • • : -Ml -.--I.- 1 -.,!• i /
Parameter i Description Use in Model Units Applicable Re quired or
i ' - i ; ' •-• :" - -•""- . ". ".: --.-'. -. ;, •- ,:. ,.WMU|'j •' .-- -Optional j
Depth to the water
table
Saturated zone
thickness
Saturated zone
hydraulic
conductivity
Ground-water
hydraulic gradient
Distance to nearest
surface water body
The depth of the zone between the land
surface and the water table
Thickness of the saturated zone of the
aquifer
Hydraulic conductivity of the saturated
zone, or the permeability of the saturated
zone in the horizontal direction.
Regional horizontal ground-water gradient
The distance from the unit to due nearest
water body
Used to predict travel time.
Delineates the depth over
which leachates can mix with
ground waters.
With hydraulic gradient, used
to calculate ground-water flow
rates.
With hydraulic conductivity,
used to calculate the ground-
water flow rate.
Affects the calculation of
ground-water mounding at a site
Meters (m)
Meters (m)
Meters per year
(m/yr)
Meters per meter
(m/m)
Meters (m)
AII :
All i
All
All
SI
Optional
Optional
Optional
Optional
Optional
b.
degradation rate which overrides the
IWEM default. A user can choose to
include degradation due to hydroly-
sis and biodegradation in the overall
degradation rate.
Tier 2 Results
After providing site-specific inputs, the
user generates design recommendations for
each constituent by launching EPACMTP
from within IWEM. EPACMTP will then sim-
ulate the site and determine the 90th per-
centile exposure concentration for each
design scenario. IWEM determines the mini-
mum recommended design at a 90th per-
centile exposure concentration by performing
10,000 Monte Carlo simulations of
EPACMTP for each waste constituent and
design. Upon completion of the modeling
analyses, IWEM will display the minimum
design recommendation and the calculated,
location-specific LCTVs based on the 90th
percentile exposure concentration.
The overall result of a Tier 2 analysis is a
design recommendation similar to the Tier 1
analysis. However, the basis for the recom-
mendation differs slightly. To illustrate the
similarities and differences between the
results from the two tiers, the remainder of
this section continues the example Tier 1
evaluation through a Tier 2 evaluation. In the
Tier 1 example, the disposal of toluene and
styrene in a proposed landfill is evaluated.
The expected leachate concentration for
toluene is 1.6 mg/L and the expected
leachate concentration for styrene is j 1.0
mg/L. In Tier 2, after inputting the site-spe-
cific data summarized in Table 9 and using
default data for the remaining parameters,
the user can then launch the EPACMTP
model simulations.
After completing the EPACMTP model
simulations, IWEM produces the results on
screen. Table 10 presents the detailed results
of a Tier 2 analysis for the no liner/i^i situ
soils scenario. The data presented in this
table are similar to the data presented in the
Tier 1 results, but the Tier 2 analysis expands
7A-30
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Protecting Ground Water—Assessing Risk
Table 9.
.A Sample Set of Site-Specific Data for Input to Tier 2
Parameters ; • Site-Specific Data i|
• Infiltration rate*
Waste management unit area
Waste management unit depth
Depth to the water table
Aquifer thickness
Toxicity standards '
Distance to a well
Local climate: Madison, WI
Soil type: fine-grained soil
15,000 m*
2m
10m . :• . .
25m
Compare to all
150 m
* The Tier 2 model uses an infiltration rate for the liner scenarios
based on local climate and soil data.
the information provided to
the user. It includes additional
information regarding the tox-
icity standard, the reference
ground-water concentration
(RGC), and the 90th per-
centile exposure concentra-
tion. The toxicity standard is
included because-the user can
select specific standards, pfo:
vide a user-defined standard,
or compare to all standards. In
this example, all standards
were selected; the user can
identify the result for each
standard from a single table.
The LCTV continues to repre-
sent the maximum leachate •
Table 10:
Example of Tier 2 Detailed'Summary Table - No Liner/In situ Soils
^
Constituent Leachale'
Concentration
i (mg/L)
LCTV ; Toxicity Ref.
(mg/L) Standard Groundr
;• water
".!; - Cone. (mg/L)
90th Percentile Protective?
Exposure
Concentration
(mg/L) / •
100-42-5 Styrene 1.0
100-42-5 Styrene " 1.0 -
100-42-5'; Styrene 1.0
• ... . . - - • •
108-88-3 Toluene 1.6
'108-88-3 Toluene 1.6
108-88-3 Toluene 1.6
8.3 0.83 MCL 0.1
8.3 29.88 HBN - 3.6
Ingestion
Non-
Cancer
8.3 40,67 . . HBN- :• 4.9
; ' Inhalation
Non-
cancer
: 8.3' 8.3 MCL 1
8.4 10.92 HBN - 1.3
Ingestion
Non-
cancer
8.4 41.16 HBN- 4.9
Inhaktion
Non-
cancer
0.1201 No
0.1201 Yes
0.1201 Yes,
0.1922 Yes
0.1894 Yes
0.1894 Yes
-7A-31
-------
Protecting Ground Water—Assessing Risk
concentration for a design scenario that is
still protective for a reference ground-water
concentration, but the LCTV is not the basis ,
for the design recommendation. .; -•:
The RGC and 90th percentile exposure
concentration are provided because they are ,
the point of comparison for the Tier 2 analy-
sis. (The LCTV, however, continues to provide
information about a threshold that might be
useful for pollution prevention or waste mini-
mization efforts.) As shown in Table 10, the
no liner/in situ soils scenario is protective for
toluene because all of the 90th percentile
exposure concentrations are less than the
three RGCs for toluene, while die no liner/in
situ soils scenario is not protective for styrene
for the MCL comparison. For that standard,
the 90th percentile exposure concentration
(0.1201 mg/L) exceeds the RGC (0.1 mg/L).
In this case, 1WEM would launch EPACMTP
to evaluate a clay liner to determine whether
that liner design would be protective.
Table 11 provides the single clay liner
results for a Tier 2 analysis.-As shown in the
table, the single clay liner is protective
because the 90th percentile exposure concen-
tration (0.0723 mg/L) is less than the refer- ..
ence ground-water concentration (0.1 mg/L).
In addition, under the "Protective?" column,
IWEM refers the user, to the appropriate liner
result if a:les§;;stringent design is^ec'cm- . ,.
mended. In Table 11, the user is referred to
the no liner/in situ soils results for the HBN-
based ingestion and inhalation results
because, as shown in Table 10, the no
liner/in situ soils scenario is protective. If a
Tier 2 analysis determines that a single clay
liner is protective for all constituents, then •
IWEM would not continue to an evaluation ,
of a composite liner. For this example of
styrene and toluene disposed of in a landfill,
the recommended minimum design is a sin-
gle clay liner, because the 90th percentile
exposure concentration (0.0723) is less than
theMCL-basedRGC(O.l). :
2. What Do the Results Mean
and How Do / Interpret Them?
The Tier 2 analysis provides LCTVs and
recommendations for a minimum protective
design. In the Tier 1 analysis, that recommen-
dation is based on a comparison of expected
.leachate concentrations to LCTVs to [determine
whether a design scenario is protective. In the
Table 11:
Example of Tier 2 Detailed Summary Table - Single Clay Liner
CA$# Constituent Leachate DAB LCTV
= ! . Concentration ' ' ". (mg/L)
j : (mg/L) : ; :
Toxicity Ref.
Standard Ground-
water
Cone. (mg/L)
;90th Percentile Protective? j
Expbsfire : • '
Concentration ; : ;
.. ^(nig/I) ";. .;;r i
100-42-5 Styrene
100-42-5 Styrene
100-42-5 Styrene
1.0 14 1.4 MCL 0.1 . .
1.0 14 50.4 HBN - 3.6 "
Ingestion
Non-
Cancer
1.0 14 . . ; 68.6 HBN - 4.9
Inhalation
Non-
cancer
0.0723 , Yes
0.0722 ! See No liner
Results ;
0.0722 ; See No liner
Results
7A-32
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Protecting Ground Water—Assessing Risk
Tier 2 analysis, LCTVs can be .used to help
waste managers determine whether waste min-
imization techniques might lower leachate
concentrations and enable them to use less
costly unit designs, but IWEM does not need
to calculate an LCTV to make a design recom-
mendation. If the 90th percentile ground-
water concentration does not exceed the
specified RGC, then the evaluated design sce-
nario is protective for that constituent. If the
90th percentile ground-water concentrations
for all constituents under the no liner/in situ
soils scenario are below their respective RGCs ,
then IWEM will recommend that no liner/in
situ soils is needed to protect the ground
water. If the 90th percentile ground-water con-
centration of any constituent exceeds its RGC,
then a single clay liner is recommended (or, in
the case of land application units, land appli-
cation is not recommended). Similarly, if the
90th percentile ground-water concentration of
any constituent under the single clay liner sce-
nario exceeds its RGC, then a composite liner
is recommended. As previously noted, howev-
er, you may decide to conduct a Tier 3 site-
specific analysis to determine which design
scenario is most appropriate. See the ensuing
section on Tier 3 analyses for further informa-
tion. For waste streams with multiple con-
stituents, the most protective liner design that
is recommended for any one constituent is the
overall recommendation. As in the Tier 1 eval-
uation, pollution prevention, recycling, and
treatment-practices could be considered when
the protective standard of a composite liner is
exceeded if you decide not to undertake a Tier
3 assessment to reflect site-specific conditions.
If the. Tier 2 analysis found land applica-
tion to be appropriate for the constituents of
concern, then a new land application system
may be considered (after evaluating other fac-
tors). Alternatively, if the waste has one or
more "problem" constituents that make land
application inappropriate, the user might
consider pollution prevention, recycling, and
treatment options for those constituents. If,
after conducting the Tier 2 evaluation, the
user is not satisfied 'with the resulting recom-
mendations, or if site-specific conditions
seem likely to suggest a different conclusion
regarding the appropriateness of land applica-
tion of a waste, then the user can conduct a
more in-depth, site-specific, ground-water
risk analysis (Tier 3).
In addition to the Tier 2 evaluation, other
fate and transport models have been devel-
oped that incorporate location-specific consid-
erations, such as the American Petroleum
Institutes (API's) Graphical Approach for
Determining Site-Specific Dilution-Attenuation
Factors.n API developed its approach to calcu-
late facility-specific DAFs quickly using
graphs rather than computer models. Graphs
visually indicate the sensitivity to various
parameters. This approach can be used for
impacted soils located above or within an
aquifer. This approach accounts for attenua-
tion with distance and time due to
advective/dispersive processes. API's approach
has a preliminary level of analysis that uses a
small data set containing only measures of the
constituent plumes geometry. The user can
read other necessary factors off graphs provid-
ed as part of the approach. This approach also
has a second level of analysis in which the
user can expand the data set to include site-
specific measures, such as duration of con-
stituent leaching, biodegradation of
constituents, or site-specific dispersivity val-
ues. At either level of analysis, the calculation
results in a DAE This approach is not appro-
priate for all situations; for example, it should
not be used to estimate constituent concentra-
tions in active ground-water supply wells or
to model very complex hydrogeologic set-
tings, such as fractured rock. It is recom-
mended that you consult with the appropriate
state agency to discuss the applicability of the
API approach or any other location-adjusted
model prior to use.
12 A copy of API's user manual, The Technical Background Document and User Manual (API Publication 4659),
can be obtained from the American Petroleum Institute, 1220 L Street, NW, Washington, DC 20005,
202 682-8375.
7A-33
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Protecting Ground Water—Assessing Risk
D. Strengths and
Limitations
Listed below are some of IWEMs strengths
and limitations that the user should be aware of:
7. Strengths.
• The tool is relatively easy to use and
requires a minimal amount of data
and modeling expertise.
• The tool can perform rapid Tier 1
screening evaluations. Tier 2 evalua-
tions allow for many site-specific
adjustments.
• The tool is designed to be flexible
with respect to the availability of site-
specific data for a Tier 2 evaluation.
The user needs to provide only a
small number of inputs, but if more
data are available, the tool can
accommodate their input.
• Users can enter their own infiltration
rates to evaluate additional design
scenarios and still use IWEM to con-
duct a risk evaluation.
• The user can modify RGC values,
when appropriate, and in consulta-
tion with other stakeholders.
• The user can modify properties of
the 226 constituents (e.g., adding
biodegradation), and can add addi-
tional constituents for evaluation.
• The tool provides recommendations
for protective design systems. It can
also be used to evaluate whether ,
waste leachate reduction measures
would be appropriate.
2. Limitations
• IWEM considers only exposures
from contact with contaminated
ground water via ingestion of drink-
ing water and inhalation while show-
ering. IWEM does not consider
vapor intrusion into buildings. It also
does not address potential risks
through environmental pathways
other than ground water, such as
volatile emissions from a WMU, sur-
face runoff and erosion, and; indirect
exposures through the food chain
pathway. Other chapters in this'
Guide, however, address ways to
assess or control potential risks via
such other pathways.
The use of a waste concentration to
leachate concentration ratio of
10,000 in IWEM Tier 2 may overesti-
mate the amount of contaminant
mass in the WMU, allowing the
modeling results to approach non- •
depleting source steady-state values
for WMUs without engineered liners.
This may result in an underestima-
tion of the Tier 2 LCTVs. ;
IWEM considers only human health
risks. Exposure and risk to ecological
receptors are not included.
The conceptual flow model used in
E'PACMTP in conjunction with
IWEM Tier 2 data input constraints
might produce ground-water veloci-
ties that might be greater than can be
assumed based on the site-specific
hydraulic conductivity and hydraulic
gradient values. The maximum val-
ues that the velocities can reach are
limited'by a model constraint that
appropriately prevents the modeled
water level from rising above the
ground surface. Despite this !con-
straint, modeled velocities might be
greater than expected velocities based
on site-specific hydraulic conductivi-
ty and hydraulic gradient.
7A-34
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Protecting Ground Water—Assessing Risk
The risk evaluation in IWEM is based
on the ground-water concentration of
. individual waste constituents. IWEM
does not address the cumulative risk
due to simultaneous exposure to mul-
tiple constituents (although it does
use a carcinogenic risk level at the
conservative end of EPA's risk range).
IWEM is not designed for sites with
complex hydrogeology, such as frac-
tured (karst) aquifers.
The tool is inappropriate for sites
where non-aqueous phase liquid
(NAPL) contaminants are present.
IWEM does not account for all possi-
ble fate and transport processes. For
example, colloid transport might be
important at some sites but is not
considered in IWEM. While the user
can enter a constituent-specific
degradation rate constant to account
for biodegradation,. IWEM simulates
biodegradation in a relatively simple
way by assuming the rate is the same
in both the unsaturated and the satu-
rated zones.
E. Tier 3: A Comprehensive
Site-Specific Evaluation
If the Tier 1 and Tier 2 evaluations do not
adequately simulate conditions at a proposed
site, or if you decide that sufficient data are
available to skip a Tier 1 or Tier 2 analysis, a
site-specific risk assessment could be consid-
ered.13 In situations involving a complex
hydrogeologic setting or other site-specific
factors that are not accounted for in IWEM, a
detailed site-specific ground-water fate and
transport analysis might be appropriate for
determining risk to ground water and evalu-
ating alternative designs or application rates.
It is recommended that you consult with the.
appropriate state agency and use a qualified
s it important to use
qualified professional?
Fate,and transport modeling can be
very co*mplex, appropnate training
, and experience are required to cor- -
rectly use and interpret models
Incorrect'fate and transport modeling
can-result iri.a liner^system that is not
rrx X -i^ f <. ""
* sufficiently protective or an mappro-
*priate'"land application rate
To avoid incorrect analyses; "check to
see if the professional has sufficient
training and experience at analyzing <
ground-water flow^and contaminant
fate and transport. * -
professional experienced in ground-water
modeling. State officials and appropriate
trade associations might be able to suggest a
good consultant to perform the analysis.
1. How is a Tier 3 Evaluation
Performed?
A Tier 3 evaluation will generally involve a
more detailed site-specific analysis than Tier
2. Sites for which a Tier 3 evaluation might
be performed typically involve complex and
heterogeneous hydrogeology. Selection and
application of appropriate ground-water
models require a thorough understanding of
the waste and the physical, chemical, and
hydrogeologic characteristics of the site.
A Tier 3 evaluation should involve the fol-
lowing steps:
• Developing a conceptual hydrogeo-
logical model of the site.
• Selecting a flow and transport simu-
lation model.
• Applying the model to the site.
" For example, if ground-water flow is subject to seasonal variations, use of the Tier 2 evaluation tool
might not be appropriate because the model is based on steady-state flow conditions.
7A-35
-------
Protecting Ground Water—-Assessing Risk
As with all modeling, you should consult
with the state before investing significant'
resources in a site-specific analysis. The state
might have a list of preferred models and
might be able to help plan the fate and trans-
port analysis.
a. Developing a Conceptual
Hydrogeological Model
The first step in the site-specific Tier 3
evaluation is to develop a conceptual hydro-
geological model of the site. The conceptual
model should describe the key features and
characteristics to be captured in the fate and
transport modeling. A complete conceptual
hydrogeological model is important to ensure
that the fate and transport model can simu-
late the important features of the site. The
conceptual hydrogeological model should
address questions such as:
• Does a confined aquifer, an uncon-
fined aquifer, or both need to be sim-
ulated?
• Does the ground water flow through
porous media, fractures, or a combi-
nation of both?
• Is there single, or are there multiple,
hydrogeologic layers to be simulated?
• Is the hydrogeology constant or vari-
able in layer thickness?
• Are there other hydraulic sources or
sinks (e.g., extraction or injection
wells, lakes, streams, ponds)?
• What is the location of natural no-
flow boundaries and/or constant
head boundaries?
• How significant is temporal (season-
al) variation in ground-water flow
conditions? Does it require a tran-
sient flow model?
• What other contaminant sources are
present?
• What fate processes are likely to be
significant (e.g. sorption and
biodegradation)? ;
• Are plume concentrations high
enough to make density effects sig-
nificant?
b. Selecting a Fate and Transport
Simulation Model
Numerous computer models exist to simu-
late ground-water fate and transport.
Relatively simple models are often based on
analytical solutions of the mathematical
equations governing ground-water flow and
solute transport equations. However, such
models generally cannot simulate the -com-
plexities of real world sites, and for a rigor-
ous Tier 3 evaluation, numerical models
based on finite-difference or finite-element
techniques are recommended. The primary
criteria for selecting a particular model
should be that it is consistent with the char-
acteristics of the site, as described in the con-
ceptual site hydrogeological model, and that
it is able to simulate the significant processes
that control contaminant fate and transport.
In addition to evaluating whether a model
will adequately address site characteristics,
the following questions should be answered
to ensure that the model will provide accu-
rate, verifiable results:
• What is the source of the model?
How easy is it to obtain and is the
model well documented?
• Are documentation and user's manu-
als available for the model? If yes, are
they clearly written and do they pro-
vide sufficient technical background
on the mathematical formulation and
solution techniques?. :
7A-36
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Protecting Ground Water—Assessing Risk
"What are some useful'resources'for
selecting,a/g£oun&water fate and
transport^ model?, * -, *' /^y
The following resources carfhelp t
select appropriate modeling software:
^ v<
• Ground Water Modeling Compendium,
Second Edition (U.S- EPA, 1994c)
/ *
• Assessment Framework for Ground-
Water Modeling Applications (U.S. EPA,
1994b) -, >" '
^- ^" N ' ^ <• -s ^ f "
• Technical Guide, to Ground-wafer Model
Selection at Sites Contaminated with
' Radioactive Substances (l/S. EPA,
1994a) / ' -
" f ^
• - EPA% Center for Subsurface Modeling
Support (CSMoS—RSKERL, Ada,
" Oklahoma) % , ^ '
"> 4 "4
• Anderson, Mary P. and William. W.
Woessner. Applied Gromdwater„
Modeling: Simulation of Flow and
Advective Transport'(Academic Press,
1992)
• EPA regional offices" ,
• Has the model been verified against
analytical solutions and other mod-
els? If yes, are the test cases available
so- that a professional consultant can
test the model on his/her computer
system?
• Has the model been validated using
field data?
Table 12 provides a brief description of a
number of commonly used ground-water fate
and transport models.
1 c. Applying the Model to the Site
For proper application of a ground-water
flow and transport model, expertise in hydro-
geology and the principles of flow and trans-
port, as well as experience in using models
and interpreting model results are essential.
The American Society for Testing and Materials
(ASTM) has developed guidance that might be
useful for conducting modeling. A listing of
guidance material can be found in Table 13.
The first step in applying the model to a
site is to calibrate it. Model calibration is the
process of matching model predictions to
observed data by adjusting the values of
input parameters. In the case of ground-water
modeling, the calibration is usually done by
matching predicted and observed hydraulic
head values. Calibration is important even for
well-characterized sites, because the values of
measured or estimated model parameters are
always subject to uncertainty. Calibrating the
flow model is usually achieved by adjusting
the value(s) of hydraulic conductivity and
recharge rates. In addition, if plume monitor-
ing data or tracer test data are available,
transport parameters such as dispersivity, and
sorption and degradation parameters can also
be calibrated. A properly calibrated model is
a powerful tool for predicting contaminant
fate and transport. Conversely, if no calibra-
tion is performed due to lack of suitable site
data, any Tier 3 model predictions will
remain subject to considerable uncertainty.
At a minimum, a site-specific analysis
should' prawide estimated leachate concentra-
tions at specified downgradient points for a
proposed design. For landfills, surface
impoundments and waste piles, you should
compare these concentrations to appropriate
MCLs, health-based standards, or state stan-
dards. For land application units, if a waste
leachate concentration is below the values
specified by the state, land application might
be appropriate. Conversely, if a leachate con-
centration is above state-specified values,
land application might not be protective of
the ground water.
7A-37
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Protecting Ground Water—Assessing Risk
• -Table.12.
Example Site-Specific Ground-Water Fate and Transport Models
Model Name Description
MODFLOW
MODFLOW is a 3-D, ground-water flow model for steady state and transient simulation of
saturated flow problems in confined and unconfined aquifers, it calculates flow rates;and
water balances. The model includes flow towards wells, through riverbeds, and into drains.
MODFLOW is the industry standard for ground-water modeling that was developed ,and
still maintained by the United States Geological Survey (USGS). MODFLQW-2000 is; the
current version. MODFLOW is a public domain model; numerous pre- and post-processing
software packages are available commercially. MODFLOW can simulate ground-water flow
only. In order to simulate contaminant transport, MODFLOW must be usedjn conjunction
with a compatible solute transport model (MT3DMS, see below).
MODFLOW and other USGS models can be obtained from the • USGS Web site- at •:
.
MT3DMS
Modular 3-D Transport model (MT3D) is commonly used in contaminant transport, model-
ing and remediation assessment studies. Originally developed for EPA, the current version is
known as MT3DMS. MT3DMS has a comprehensive set of options and capabilities for sim-
ulating advection, dispersion/diffusion, and chemical reactions of contaminants in ground-
water flow systems under general hydrogeologic conditions. MT3DMS retains the same
modular structure of the original MT3D code, similar to that implemented in MODFLOW.
The modular structure of the transport model makes it possible to simulate advection, dis-
persion/diffusion, source/sink mixing, and chemical reactions separately without reserving
computer memory space for unused options. New packages involving other transport
processes and reactions can be added to the model readily without having to modify the
existing code.
NOTE: The original version of this model known as MT3D, released in 1991, was based on
a mathematical formulation which could result in mass-balance errors. This version should
be avoided.
MT3DMS is maintained at the University of Alabama, and can be obtained at: ;
. MT3DMS is also included, along with MODFLOW, in seVeral
commercial ground-water modeling software packages. - ;
B1OPLUME-1II
BIOPLUME-1II is a 2-D, finite difference model for simulating the natural attenuation of
organic contaminants in ground water due to the processes of advection, dispersion/sorp-
tion, and biodegradation. Biotransformation processes are potentially important in the
restoration of aquifers contaminated with organic pollutants. As a result, these processes
require valuation in remedial action planning studies associated with hydrocarbon contami-
nants. The model is based on the USGS solute transport code MOC. It solves the soljute
transport equation six times to determine the fate and transport of the hydrocarbons, the
electron acceptors (O2, NO3', Fe3*, SO42', and CO2), and the reaction byproducts (Fe2»). A
number of aerobic and anaerobic electron acceptors (e.g., oxygen, nitrate, sulfate, ircjn (III),
and carbon dioxide) have been considered in this model to simulate the biodegradation of
organic contaminants. Three different kinetic expressions can be used to simulate the aero-
bic and anaerobic biodegradation reactions. ;
B1OPLUME-III and other EPA supported ground-water modeling software can be obtained
via the EPA Center for Subsurface Modeling Support at the RS Kerr Environmental Research
Lab in Ada, Oklahoma: .
7A-38
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Protecting Ground Water—Assessing Risk
A well-executed site-specific analysis can be
a useful instrument to anticipate and avoid
potential risks. A poorly executed site-specific
analysis, however, could over- or under-
emphasize risks, possibly leading to adverse
human health and environmental effects, or
costly cleanup liability, or it could overempha-
size risks, possibly leading to the unnecessary
expenditure of limited resources. If possible,
the model and the results of the final analyses,
including input and output parameters and
key assumptions, should be shared with
stakeholders. Chapter 1—Understanding Risk
and Building Partnerships provides a more
detailed description of activities to keep the
public informed and involved.
Table 13. ASTM Ground-Water Modeling Standards
J ^ ^x •* ^ gp * . >•**
-The American Society for Testing'and'-Materials (ASTM)/Section D-18'.2,LlCf concerns
subsurfacffiuid-flow (ground-water),modelmg. The ASTM ground-water modeling section
' is'one of several task groups/funded'under a cooperative a'greement"between USGS and EPA
to develop consensus^standards'for the environmental'industry and keep the modeling
community rnformedas to'the progress ferng made ^development of modeling standards.
'The standards being developedbyT>18.2L10 are-"guides" in ASTM terminology, which
means that the contenCis analogous to that of EPA guidance documents. The ASTM mod-
eling guides are intended to document the state-of-the-science related to Carious topics in
subsurface-modeling.^ , ( ^-^-,
The following standards have been developed by D-18.21.10 and passedjDy ASTM.
They can be purchased from ASlU, bycallmg 610^832-9585. To order or browse for pub-
lications, visit ASTM's Website .
D-5447 Guide for Application of a Ground-Water Flow Model to a Site-Specific Problem
jr-// />
D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site-Specific
Information ,~ ' " *
D-5609 Guide for Defining Boundary Conditions in Ground-Water Flow Modeling
D-5610 Guide for Defining Initial Conditions in Ground-Water Flow Modeling
D-5611 Guide for Conducting a ^Sensitivity Analysis for a Ground-Water Flow Model
Application » ' ,
D-5718 Guide for Documenting a'Ground-Water Fkrwr Model Application
D-5719 Guide to Simulation of Subsurface Air Flow Using Ground-Water Flow
Modeling Codes. , '
D-5880 Guide for Subsurface Flow and Transport Modeling
D-5981 Guide for Calibrating a Ground-Water Flow^Model Application
A compilation of most of the current modeling and aquifer testing standards also can be
purchased. The title of the publication is ASTM Standards on Analysis ofHydrologic
Parameters and Ground Water Modeling, publication number 03-418096-38.
For more information by e-mail, contact service@astm.org
7A-39
-------
Protecting Ground Water-^Assessing Risk
— Assessing Risk Activity List —-—
D Review the risk characterization tools recommended by this chapter.
D Characterize the waste in accordance with the recommendations of Chapter 2 — Characterizing
Waste. . ;
D Obtain expected leachate concentrations for all relevant waste constituents.
D If a Tier 1 evaluation is conducted, understand and use the Tier 1 Evaluation to obtain recbmmen-
dations for the design of your waste management unit (as noted previously, you can skip the Tier 1
analysis and proceed directly to a Tier 2 or Tier 3 analysis). (
D If a design system or other measures are recommended in a Tier 1 analysis, perform a Tier 2 analy-
sis if you believe the recommendations are overly protective. Also, if data are available, you can
conduct a Tier 2 or Tier 3 analysis without conducting a Tier 1 evaluation.
D If your site characteristics or your waste management needs are particularly complex, or do not
adequately simulate conditions reflected in a Tier 1 or Tier 2 analysis, consult with your state and a
qualified professional and consider a more detailed, site-specific Tier 3 analysis.
7A-40
-------
Protecting Ground Water—Assessing Risk
Resources
ASTM. 1996. ASTM Standards on Analysis of Hydrologic Parameters and Ground Water Modeling,
Publication Number 03-418096-38.
ASTM. 1993. D-5447 Guide for Application of a Ground-Water Flow Model to a Site-Specific
Problem.
ASTM. 1993. D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site-specific
Information.
ASTM. 1994. D-5609 Guide for Defining Boundary Conditions in Ground-Water Flow Modeling.
ASTM. 1994. D-5610 Guide for Defining Initial Conditions in Ground-Water Flow Modeling.
ASTM. 1994. D-5611 Guide for Conducting a Sensitivity Analysis for a Ground-Water Flow Model
Application.
ASTM. 1994. D-5718 Guide for Documenting a Ground-Water Flow Model Application.
ASTM. 1994. D-5719 Guide to Simulation of Subsurface Air Flow Using Ground-Water Flow
Modeling Codes.
ASTM. 1995. D-5880 Guide for Subsurface Flow and Transport Modeling.
ASTM. 1996. D-5981 Guide for Calibrating a Ground-Water Flow Model Application.
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.
Berner, E. K. and R. Berner. 1987. The Global Water Cycle: Geochemistry and Environment.
Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention,
and Remediation.
Lee, C. 1992. Environmental Engineering Dictionary, 2d. Ed.
Sharma, FL, and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills.
Speidel, D., L. Ruedisili, and A. Agnew. 1988. Perspectives on Water: Uses and Abuses.
-------
Protecting Ground Water—Assessing Risk
Resources (cont.)
U.S. EPA. 2002a. Industrial Waste Management Evaluation Model (IWEM) Technical
Background Document. EPA530-R-02-012.
U.S. EPA. 2002b. The User's Guide for the Industrial Waste Management Evaluation Model.
EPA530-R-02-013.
U.S. EPA. 2002c. EPACMTP Data/Parameters Background Document.
U.S. EPA. 2002d. EPACMTP Technical Background Document.
U.S. EPA. 1997a. Exposure Factors Handbook. EPA600-P-95-002E
U.S. EPA. 1997b. Guiding Principles for Monte Carlo Analyses. EPA630-R-97-001.
U.S. EPA. 1994a. A Technical Guide to Ground-Water Model Selection at Sites Contaminated
with Radioactive Substance. EPA 4-2-R-94-012.
U.S. EPA. 1994b. Assessment Framework for Ground-Water Modeling Applications. EPA500-B-
94-003.
U.S. EPA. 1994c. Ground-Water Modeling Compendium, Second Edition. EPA500-B-94-003.
U.S. EPA. 1991. Seminar Publication: Site Characterization for Subsurface Remediation.
EPA625-4-91-026.
U.S. EPA. 1989. Exposure Assessment Methods Handbook.
U.S. EPA. 1988. Selection Criteria For Mathematical Models Used In Exposure Assessments:
Ground-water Models. EPA600-8-88-075.
U.S. EPA. 1988. Superfund Exposure Assessment Manual.
7A-42
-------
Part IV
Protecting Ground Water
Chapter 7: Section B
Designing and Installing Liners
Technical Considerations for New Surface
Impoundments, Landfills, and Waste Piles
-------
Contents
I. In-Situ Soil Liners : 7B~1
II. Single Liners 'i 7B~2
y-n n
A. Compacted'Clay Liners :
B. Geomembranes or Flexible Membrane Liners ; 7B"10
yn 1 y
C. Geosynthetic Clay Liners • i
yr> nT
III. Composite Liners '
IV. Double Liners (Primary and Secondary Lined Systems) ,- 7B-23
V. Leachate Collection and Leak Detection Systems , 7B'24
A. Leachate Collection System 1 7B~2
yn no
B. Leak Detection System i
C. Leachate Treatment System ••• •;
VI. Construction Quality Assurance and Quality Control : • 7B-29
A. Compacted Clay Liner Quality Assurance and Quality Control 7B-32
B. Geomembrane Liner Quality Assurance and Quality Control ••••••• 7B-32
C. Geosynthetic Clay Liner Quality Assurance and Quality Control , 7B'33
D.Leachate Collection System Quality Assurance and Quality Control • 7B-34
Designing and Installing Liners Activity List , - : ; 7B~3
". 7B-37
Resources i
,. 7B-43
Appendrx I
Figures;
Figure 1. Water Content for Achieving a Specific Density i 7B"6
Figure 2: Two Types of Footed Rollers < 7B~8
Figure 3: Four Variations of GCL Bonding Methods ; 7fi-19
Figure 4: Typical Leachate Collection System • | 7B'25
Figure 5: Typical Geonet Configuration ,- \ 7B"27
-------
Protecting Ground Water—Designing and Installing Liners
Designing and Installing Liners-Technical
Considerations for New Surface
Impoundments; Landfills, and Waste Piles
This chapter will help you:
• Employ liner systems where needed to protect ground water from
contamination.
• Select from day liners, synthetic liners, composite liners, leachate
collection systems, and leak detection systems as appropriate.
• Consider technical issues carefully to ensure that the liner system
will function as designed.
Once risk has been characterized
and the most appropriate
design system is chosen, the
next step is unit design. The
Industrial Waste Management
Evaluation Model (IWEM), discussed in
Chapter 7, Section A—Assessing Risk can be
used to determine appropriate design system
recommendations. A critical part of this
design for new landfills, waste piles, and sur-
face impoundments is the liner system. The
liner system recommendations in the Guide
do not apply to land application units, since
such operations generally do not include a
liner system as part of their design. (For
design of land application units, refer to
Chapter 7, Section C—Designing a Land
Application Program.) You should work with
your state agency to ensure consideration of
any applicable design system requirements,
recommendations, or standard practices the
state might have. In this chapter, sections I
though IV discuss four design options—no
liner/in-situ soils, single liner, composite liner,
and double liner. Section V covers leachate
collection and leak detection systems, and
section VI discusses construction quality
assurance and quality control.
I. In-Situ Soil
Liners
For the purpose of the Guide, in-situ soil
refers to simple, excavated areas or impound-
ments, without any additional engineering
controls. The ability of natural soils to hinder
transport and reduce the concentration of
constituent levels through dilution and atten-
uation can provide sufficient protection when
the initial constituent levels in the waste.
stream are very low, when the wastes are
inert, or when the hydrogeologic setting
affords sufficient protection.
What are the recommendations
for in-situ soils?
The soil below and adjacent to a waste
management unit should be suitable for con-
struction. It should provide a firm foundation
for the waste. Due to the low risk associated
with wastes being managed in these units, a
liner might not be necessary; however, it is
still helpful to review the recommended loca-
tion considerations and operating practices for
the unit.
7B-1
-------
Protecting Ground Water—Designing and Installing Liners
What technical issues should be
considered with the use of in-situ
soils?
In' units using in-situ natural soils, con-
struction and design of an engineered liner
will not be necessary; however, there are still.
technical concerns to consider. These include
the following:
• The stability of foundation soils.
« The compatibility of the waste with
native soils.
• The location where the unit will be
sited.
• The potential to recompact existing
soils.
Potential instability can occur in the foun-
dation soil, if its load-bearing capacity and
resistance to movement or consolidation are
insufficient to support the waste. The ground-
water table or a weak soil layer also can influ-
ence the stability of the unit. You should take
measures, such as designing maximum slopes,
to avoid slope failure during construction and
operation of the waste management unit. Most
soil slopes are stable at a 3:1 horizontal to ver-
tical inclination. There are common sense
operating practices to ensure that any wastes
to be managed on in-situ soils will not inap-
propriately interact with the soils. When using
in-situ soils, refer to Chapter 4—Considering
the Site. Selecting an appropriate location will
be of increased importance, since the added
barrier of an engineered liner will not be pre-
sent. Because in-situ soil can have non-homo-
geneous material, root holes, and cracks, its
performance can be improved by scarifying
and compacting the top portion of the in-situ
natural soils.
II. Single Liners
If the risk evaluation recommended the use
of a single liner, the next step is to determine
the type of single liner system most appropri-
ate for the site. The discussion below address-
es three types of single liner systems:
compacted clay liners, geomembranfe liners,
and geosynthetic clay liners. Deternyining
which material, or combination of materials, is
important for protecting human health and
the environment.1
A. Compacted Clay Liners
A compacted clay liner can serve; as a single
liner or as part of a composite or double liner
system. Compacted clay liners are composed
of natural mineral materials (natural soils),
bentonite-soil blends, and other materials^
placed and compacted in layers called lifts. If
natural soils at the site contain a significant
quantity of clay, then liner materials can be
excavated from onsite locations known as bor-
row pits. Alternatively, if onsite soils do not
contain sufficient clay, clay materials can be
hauled from offsite sources, often referred to
as commercial pits.
Compacted clay liners can be designed to
work effectively as hydraulic barriers. To
ensure that compacted clay liners are well
constructed and perform as they are designed,
it is important to implement effective quality
control methods emphasizing soil investiga-
tions and construction practices. Three objec-
tives of quality assurance and quality control
for compacted soil liners are to ensure that 1)
selected liner materials are suitable^ 2) liner
materials are properly placed and qompacted,
and 3) the completed liner is properly protect-
ed before, during, and after construction.
Quality assurance and quality conttol are dis-
cussed in greater detail in section VI-
7B-2
Many industry and trade periodicals, such as Waste Age, MSW Management, Solid Waste Technologies,
and World Wastes, have articles on liner types and their corresponding costs, as well as advertisements
and lists of vendors. :
-------
Protecting Ground Water—Designing and Instating Liners
What are the thickness and
hydraulic conductivity recommen-
dations for compacted day liners?
Compacted clay liners should be at least 2
feet thick and have a maximum hydraulic
conductivity of 1 x 10'7 cm/sec (4 x 10'3 .
in/sec). Hydraulic conductivity refers to the
degree of ease with which a fluid can flow
through a material. A low hydraulic conduc-
tivity will help minimize leachate migration
out of a unit. Designing a compacted clay
liner with a thickness ranging from-2 to 5 feet
will help ensure that the liner meets desired
hydraulic conductivity standards and will
also minimize leachate migration as a result
of any cracks or imperfections present in the
liner. Thicker compacted clay liners provide
additional time to minimize leachate migra-
tion prior to the clay becoming saturated.
What issues should be considered
in the design of a compacted clay
liner?
The first step in designing a compacted
clay liner is selecting the clay material. The
quality and properties of the material will
influence the performance of the liner. The
most common type of compacted soil is one
that is constructed from naturally occurring
soils that contain a significant quantity of
clay. Such soils are usually classified as CL,
CH, or SC in the Unified Soil Classification
System (USCS). Some of the factors to con-
sider in choosing a soil include soil proper-
ties, interaction with wastes, and test results
for potentially available materials.
So/7 Properties
Minimizing hydraulic conductivity is the
primary goal in constructing a soil liner.
Factors to consider are water content, plasticity
characteristics, percent fines, and percent grav-
el, as these properties affect the soilfe ability to
achieve a specified hydraulic conductivity.
Hydraulic conductivity. It is important to
select compacted clay liner materials so that
remolding and compacting of the materials
will produce a low hydraulic conductivity.
Factors influencing the hydraulic conductivi-
ty at a particular site include: the degree of
compaction, compaction method, type of clay
material used, soil moisture content, and
density of the soil during liner construction.
The hydraulic conductivity of a soil also
depends on the viscosity and density of the
fluid flowing through it. Consider measuring
hydraulic-conductivity using methods such as
American Society of Testing and Materials
(ASTM) D-5084.2
Water content. Water content refers to the
amount of liquid, or free water, contained in a
given amount of material. Measuring water
content can help determine whether a clay
material needs preprocessing, such as moisture
adjustment or soil amendments, to yield a
specified density or hydraulic conductivity.
Compaction curves can be used to depict
moisture and density relationships, using
either ASTM D-698 or ASTM D-1557, the
standard or modified Proctor test methods,
depending on the compaction equipment used
and the degree of firmness in the foundation
materials.3 The critical relationship between
clay soil moisture content and density is
explained thoroughly in Chapter 2 of EPA's
1993 technical guidance document Quality
ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous
Materials Using a Flexible Wall Permeameter.
ASTM D-698, Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort
(12,400 ft-lbfrft3 (600 kN-m/m3)).
ASTM D-1557, Test Method for Laboratory Compaction Characteristics of Soil Using Modified Effort
(56,000 ft-lbf/ft3 (2,700 kN-m/m3)).
7B-3
-------
Protecting Ground Water—Deigning and Installing Liners
Assurance and Quality Control for Waste
Containment Facilities (U.S. EPA, 1993c).
Plasticity characteristics. Plasticity char-
acteristics describe a material's ability to
behave as a plastic or moldable material.
Soils containing clay are generally categorized
as plastic. Soils that do not contain clay are
non-plastic and typically considered unsuit-
able materials for compacted clay liners,
unless soil amendments such as bentonite
clay are introduced.
Plasticity characteristics are quantified by
three parameters: liquid limit, plastic limit,
and plasticity index. The liquid limit is
defined as the minimum moisture content (in
percent of oven-dried weight) at which a soil-
water mixture can flow. The plastic limit is
the minimum moisture content at which a
soil can be molded. The plasticity index is
defined as the liquid limit minus the plastic
limit and defines the range of moisture con-
tent over which a soil exhibits plastic behav-
ior. When soils with high plastic limits are
too dry during placement, they tend to form
clods, or hardened clumps, that are difficult
to break down during compaction. As a
result, preferential pathways can form around
these clumps allowing leachate to flow
through the material at a higher rate. Soil
plasticity indices typically range from 10 per-
cent to 30 percent. Soils with a plasticity
index greater than 30 percent are cohesive,
sticky, and difficult to work with in the field.
Common testing methods for plasticity char-
acteristics include the methods specified in
ASTM D-4318, also known as Atterberg lim-
its tests.4
Percent fines and percent gravel. Typical
soil liner materials contain at least 30 percent
fines and can contain up to 50 percent gravel,
by weight. Common testing methods for per-
cent fines and percent gravel are specified in
ASTM D-422, also referred to as grain size
distribution tests.5 Fines refer to silt and clay-
sized particles. Soils with less than 30 percent
fines can be worked to obtain hydraulic con-
ductivities below 1 x lO'7 cm/sec (4 x lO'8
in./sec), but use of these soils requires; more
careful construction practices.
Gravel is defined as particles unable to
pass through the openings of a Number 4
sieve, which has an opening size equal to .
4.76 mm (0.2 in.). Although gravel itself has
a high hydraulic conductivity, relatively large
amounts of gravel, up to 50 percent b'y
weight, can be uniformly mixed with clay
materials without significantly increasing the
hydraulic conductivity of the material Clay
materials fill voids created between gravel .
particles, thereby creating a gravel-clay mix-
ture with a low hydraulic conductivity. As
long as the percent gravel in a compacted
clay mixture remains below 50 percent, cre-
ating a uniform mixture of clay and gravel,
where clay can fill in gaps, is more critical
than the actual gravel content of the mixture.
You should pay close attention to the per-
cent gravel in cases where a compacted clay
liner functions as a bottom layer to a; geosyn-
thetic, as gravel can cause puncturing in
geosynthetic materials. Controlling trie maxi-
mum particle size and angularity of the grav-
el should help prevent puncturing, as well as
prevent gravel from creating preferential flow
paths. Similar to gravel, soil particles or rock
fragments also can create preferential flow
paths. To help prevent the development of
preferential pathways and an increased
hydraulic conductivity, it is best to use soil
liner materials where the soil particles and
rock fragments are typically small (e.g., 3/4
inch in diameter).
Interactions With Waste
Waste placed in a unit can interact with
compacted clay liner materials, thereby influ-
encing soil properties such as hydraulic con-
7B-4
4 ASTM D-4318, Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.
' ASTM D-422, Standard Test Method for Particle-Size Analysis of Soils. \
-------
Protecting Ground Water—Designing and Installing Liners
ductivity and permeability. Two ways that
waste materials can influence the hydraulic
conductivity of the liner materials are
through dissolution of soil minerals and
changes in clay structure. Soil minerals can
be dissolved, or reduced to liquid form, as a
result of interaction with acids and bases. For
example, aluminum and iron in the soil can
be dissolved by acids, and silica can be dis-
solved by bases. While some plugging of soil
pores by dissolved minerals can lower
hydraulic conductivity in the short term, the
creation of piping and channels over time can
lead to an increased hydraulic conductivity in
the long term. The interaction of waste and
clay materials can also cause the creation of
positive ions, or cations. The presence of
cations such as sodium, potassium, calcium,
and magnesium can change the clay struc-
ture, thereby influencing the hydraulic con-
ductivity of the liner. Depending on the
• cation type and the clay mineral, an increased
presence of such cations can cause the clay
minerals to form clusters and increase the
permeability of the clay. Therefore, before
selecting a compacted clay liner material, it is
important to develop a good understanding
of the composition of the waste that will be
placed in the waste management unit. EPA's
Method 9100, in publication SW-846, mea-
sures the hydraulic conductivity of soil sam-
ples before and after exposure to permeants.6
Locating and Testing Material
Although the selection process for com-
pacted clay liner construction materials can
vary from project to project, some common
material selection steps include locating and
testing materials at a potential borrow or
commercial pit before construction, and
observing and testing material performance
throughout-construction. First, investigate a
potential borrow or commercial pit to deter-
mine the volume of materials available. The
next step is to test a representative sample of
soil to determine material properties such as
plasticity characteristics, percent gravel, and
percent fines. To confirm the suitability of the
materials once construction begins, you '
should consider requesting that representa-
tive samples from the materials in the borrow
or commercial pit be tested periodically after
work has started.
Material selection steps will vary, depend-
ing on the origin of the materials for the pro-
ject. For example, if a commercial pit provides
the materials, locating an appropriate onsite
borrow pit is not necessary In addition to the
tests performed on the material, it is recom-
mended that a qualified inspector make visual
observations throughout the construction
process to ensure that harmful materials, such
as stones or other large matter, are not present
in the liner material.
What issues should be considered
in the construction of a liner and
the operation of a unit?
You should develop test pads to demon-
strate construction techniques and material
'performance on a small scale. During unit con-
struction and operation, some additional fac-
tors influencing the performance of the.liner
include: preprocessing, subgrade preparation,
method of compaction, and protection against
desiccation and cracking. Each of these steps,
from preprocessing through protection against
desiccation and cracking, should be repeated
for each lift or layer of soil.
Fest Pads
Preparing a test pad for the compacted
clay liner helps verify that the materials and
methods proposed will yield a liner that
meets the desired hydraulic conductivity A
test pad also provides an opportunity to
SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods.
7B-5
-------
Protecting Ground Water—Designing and Installing Liners
demonstrate the performance of alternative
materials or methods of construction. A test
pad should be constructed with the soil liner
materials proposed for a particular project,
using the same preprocessing procedures,
compaction equipment, and construction
practices proposed for the actual liner. A
complete discussion of test pads (covering
dimensions, materials, and construction) can
be found in Chapter 2 of EPA's 1993 techni-
cal guidance document Quality Assurance and
Quality Control for Waste Containment Facilities
(U.S. EPA, 1993c). A discussion of commonly
used methods to measure in-situ hydraulic
conductivity is also contained in that chapter.
Preprocessing ..
Although some liner
materials can be ready
for use in construction
immediately after they
are excavated, many
materials will require
some degree of prepro-
cessing. Preprocessing
methods include: water
content adjustment,
removal of oversized
particles, pulverization
of any clumps, homoge-
nization of the soils, and
introduction of addi-
tives, such as bentonite.
Water content
adjustment. For natural
soils, the degree of satu-
ration of the soil liner at
the time of compaction,
known as molding water
content, influences the
engineering properties of
the compacted material.
Soils compacted at water
contents less than opti-
mum tend to have a relatively high hydraulic
conductivity. Soils compacted at water con-
tents greater than optimum tend to have low
hydraulic conductivity and low strength.
Proper soil water content revolves around
achieving a minimum dry density, which is
expressed as a percentage of the soil's maxi-
mum dry density. The minimum'dry density
typically falls in the range of 90 to 95'percent
of the soil's maximum dry density value. From
the minimum dry density range, the required
water content range can be calculated, as
shown in Figure 1. In this example the soil
has a maximum dry density of 115 Ib/cu ft.
Based upon a required minimum dry density
value of 90 percent of maximum dry density,
Figure 1.
Water Content for Achieving a Specific Density
130
120
110
100
90
80
70
T
y, =.ns
a max
Pange of Acceptable
Water Contents
wopt = 20%
= 28%
I
10 20 30
Water Content (w), %
40
50
Source: U.S. EPA, 1988.
7B-6
-------
Protecting Ground Water—Designing and Installing Liners
which is equal to 103.5 Ib/cu ft, the required
water content ranges from 10 to 28 percent.
It is less problematic to compact clay soil
at the lower end of the required water con-
tent range because it is easier to add water to
the clay soil than to remove it. Thus, if pre-
cipitation occurs during construction of a site
which is being placed at the lower end of the
required water .content range, the additional
water might not result in a soil water content
greater than the required range. Conversely, if
the site is being placed at the upper end of
the range, for example at 25 perc'ent, any
additional moisture will be excessive, result-
ing in water content over 28 percent and
making the 90 percent maximum dry density
unattainable. Under such conditions con-
struction should halt while the soil is aerated
and excess moisture is allowed- to evaporate.
Removal of oversized particles.
Preprocessing clay materials, to remove cob-
bles or large stones that exceed the maximum
allowable particle size, can improve the soil's
compactibility and protect any adjacent
geomembrane from puncture. Particle size
should be small (e.g., 3/4 inch in diameter)
for compaction purposes. If a geomembrane
will be placed over the compacted clay, only
the upper lift of clay needs to address con-
cerns regarding puncture resistance.
Observation by quality assurance and quality
control personnel is the most effective
method to identify areas where oversized par-
ticles need to be removed. Cobbles and
stones are not the only materials that can
interfere with compactive efforts. Chunks of
dry, hard clay, also.known as clods, often
need to be broken into smaller pieces to be
properly hydrated, remolded, and compact-
ed. In wet clay, clods are less of a concern
since wet clods can often be'remolded with a
reasonable compactive effort.
Soil amendments. If the soils at a unit do
not have a sufficient percentage of clay, a com-
mon practice is to blend bentonite with them
to reduce the hydraulic conductivity Bentonite
is a clay mineral that expands when it comes
into contact with water. Relatively small
amounts of bentonite, on the order of 5 to 10
percent, can be added to sand or other nonco-
hesive soils to increase the cohesion of the
material and reduce hydraulic conductivity
Sodium bentonite is a common additive
used to amend soils. However, this additive is
vulnerable to degradation as a result of con-
tact with certain chemicals and waste
leachates. Calcium bentonite, a more perme-
able material than sodium bentonite, is anoth-
er common additive used to amend soils.
Approximately twice as much calcium ben-
tonite is needed to achieve a hydraulic con-
ductivity comparable to that of sodium
bentonite. Amended soil mixtures- generally
require mixing in a pug mill, cement mixer, or
other mixing equipment that allows water to
be added during the mixing process.
Throughout the mixing and placement
processes, water content, bentonite content,
and particle distribution should be controlled.
Other materials that can be used, as soil addi-
tives include lime cement and other clay min-
erals, such as atapulgite. It can be difficult to
mix additives thoroughly with cohesive soils,
or clays; the resultant mixture might not
achieve the desired level of hydraulic conduc-
tivity throughout the entire liner.
Subgrade Preparation
It is important to ensure that the subgrade
on,which a compacted clay liner will be con-
structed is properly prepared. When a com-
pacted clay liner is the lowest component of a
liner system, the subgrade consists of native
soil or rock. Subgrade preparation for these
systems involves compacting the native soil
to remove any soft spots and adding water to
or removing water from the native soil to
obtain a specified firmness. Alternatively, in
7B-7
-------
Protecting Ground Water—Designing and Installing Liners
some cases, the compacted clay liner can be
placed on top of a geosynthetic material, such
as a geotextile. In such cases, subgrade prepa-
ration involves ensuring the smoothness of
the geosynthetic on which the clay liner will
be placed and the conformity of the geosyn-
, thetic material to the underlying material.
Compaction
The main purpose of compaction is to
, density the clay materials by breaking and
remolding clods of material into a uniform
mass. Since amended soils usually do not.
develop clumps, the primary objective of
compaction for such materials is to increase
the material's density. Proper compaction of
liner materials is essential to ensure that a
' compacted clay liner meets specified
hydraulic conductivity standards. Factors
influencing the effectiveness of compaction
efforts include: the type of equipment select-
ed, the number of passes made over the
materials by such equipment, the lift thick-
ness, and the bonding between the lifts.
Molding water content, described earlier
under preprocessing, is another factor :influ-
encing the effectiveness of compaction.
Type of equipment. Factors to consider
when selecting compaction equipment
include: the type and weight of the com-
pactor, the characteristics of any feet on the
drum, and the weight of the roller per unit
length of drummed surface. Heavy com-
pactors, weighing more than 50,000 pounds,
with feet long enough to penetrate a loose lift
of soil, are often the best types of compactor
for clay liners. For bentonite-soil mixtures, a
footed roller might not be appropriate. For
these mixtures,, where densificatipn of the
material is more important than kneading or
remolding it to meet low hydraulic conduc-
tivity specifications, a smooth-drum roller or
a rubber- tired roller might produce better
results. Figure 2 depicts two types of footed
rollers, a fully penetrating footed roller and a
partially-penetrating footed roller. '
Figure 2 Two Types of Footed Rollers
Fully Penetrating Feet on Roller
Compact Base of New, Loose Lift
of Soil into Surface of Old, Previously
Compacted Lift
Partly Penetrating Feet on Roller Do
Not Extend to Base of New, Loose
Lift of Soil and Do Not Compact New '-
Lift into Surface of Old Lrft
Source: U.S. EPA, 1993c.
7B-8
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Protecting Ground Water—Designing and Installing Liners
For placement of liners on side slopes,
consider the angle and length of the slope.
Placing continuous lifts on a gradually
inclined slope will provide better continuity
between the bottom and sidewalls of the
liner. Since continuous'lifts might be impossi-
ble to construct on steeper slopes due to the
difficulties of operating heavy compaction
equipment on these slopes, materials might
need to be placed and compacted in horizon-
tal lifts. When sidewalls are cpmpacted hori-
zontally, it is important to avoid creating
seepage planes, by securely connecting the
edges of the horizontal lift with the bottom of
the liner. Because the lift needs to be wide
enough to accommodate compaction equip-
ment, tjie thickness of the horizontal lift is
often greater than the thickness specified in
the design. In such cases, you should consid-
er trimming soil material from the construct-
ed side slopes and sealing the trimmed
surface using a sealed drum roller.
It is common for contractors to use several
different types of compaction equipment dur-
ing liner construction. Initial lifts might need
the use of a footed roller to fully penetrate a
loose lift. Final lifts also might need the use
of a footed roller for compaction, however,
they might be formed better by using a
smooth roller after the lift has been compact-
ed to smooth the surface 'of the lift in prepa-
ration for placement of an overlying
geomembrane.
Number of passes. The number of passes
made by a compactor over clay materials-can
influence the overall hydraulic conductivity
of the liner. The minimum number of passes
that is reasonable depends on a variety of
site-specific factors and cannot be general-
ized. In some cases, where a minimum cover-
age is specified, it might be possible to
calculate the minimum number of passes to
meet such a specification. At least 5 to 15
passes with a compactor over a given point
are usually necessary to remold and compact
clay liner materials thoroughly.
An equipment pass can be defined as one
pass of the compaction equipment or as one
pass of a drum over a given area of soil. It is
important to clearly define what is meant by
a pass in any quality assurance or quality
control plans. It does not matter which defin-
ition is agreed upon, as long as the definition
is used consistently throughout the project.
Lift thickness. You should determine the
appropriate thickness (as measured before
compaction) of each of the several lifts that
'will make up the clay liner. The initial thick-
ness of a loose lift will affect the compactive
effort needed to reach the lower portions of
the lift. Thinner lifts allow compactive efforts
to reach the bottom of a lift and provide
greater assurance that compaction will be suf-
ficient to allow homogenous bonding
between subsequent lifts. Loose lift thickness-
es typically range between 13 and 25 cm (5
and 10 in.). Factors influencing lift thickness
are: soil characteristics, compaction equip-
ment, firmness of the foundation materials,
and the anticipated compaction necessary to
meet hydraulic conductivity requirements.
Bonding between lifts. Since it is
inevitable that some zones of higher and
lower hydraulic conductivity, also known as
preferential pathways, will be present within
each lift, lifts should be joined or bonded in a
way that minimizes extending these zones or
pathways between lifts. If good bonding is
' achieved, the preferential pathways will be
truncated by the bonded zone between the
lifts. At least two recommended methods
exist for preparing proper bonds. The first
method involves kneading, or blending the
new lift with the previously compacted lift
using a footed roller. Using a roller with feet
long enough to fully penetrate through the
top lift and knead the previous lift improves
the quality of the bond. A second method
7B-9
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Protecting Ground Water—Designing and Installing Liners
involves using a disc harrow or similar equip-
ment to scarify, or roughen, and wet the top
inch of the recently placed lift, prior to plac-
ing the next lift. "
Protection Against Desiccation and
Cracking . .
You should consider how to protect com-
pacted clay liners against desiccation and
freezing during and after construction.
Protection against desiccation is important,
because clay soil shrinks as it dries. Depend-
ing on the extent of shrinkage, it can crack.
Deep cracks, extending through more than
one lift, can cause problems. You should
measure water content to determine whether
desiccation is occurring.
There are several ways to protect compact-
ed clay liners from desiccation. One preven-
tive measure is to smooth roll the surface with
a steel drummed roller to produce a thin,
dense skin of soil; this layer can help mini-
mize the movement of water into or out of the
compacted material. Another option is to wet
the clay periodically in a uniform manner;
however, it is important to make sure to avoid
creating areas of excessive wetness. A third
measure involves covering compacted clay
liner materials with a sheet of white or clear
plastic or tarp to help prevent against desicca-
tion and cracking. The cover should be
weighted down with sandbags or other mater-
ial to minimize exposure of the underlying
materials to air. Using a light-colored plastic
will help prevent overheating, which can dry
out the clay materials. If the clay liner is not
being covered with a geosynthetic, another
method to prevent desiccation involves cover-
ing the clay with a layer of protective cover
soil or intentionally overbuilding the clay liner
and shaving it down to liner grade.
Protection against freezing is another
important consideration, because freezing can
increase the hydraulic conductivity of ;a liner.
It is important to avoid construction during
freezing weather. If freezing does occur and
the damage affects only a shallow depth, the
liner can be repaired by rerolling the surface.
If deeper freezing occurs, the repairs might
be more complicated. For a general guide to
frost depths, see Figure 1 of Chapter 11—
Performing Closure and Post-Closure Care.
B. Geomembranes or
Flexible Membrane Liners
Geomembranes or flexible membrane lin-
ers are used to contain or prevent waste con-
stituents and leachate from escaping a, waste
management unit. Geomembranes are made
by combining one or more plastic polymers
,with ingredients such as carbon black, pig-
ments, fillers, plasticizers, processing aids,
crosslinking chemicals, anti-degradants, and
biocides. A wide range of plastic resins are
used for geomembranes, including high den-
sity polyethylene (HDPE), linear low density
polyethylene (LLDPE), low density linear
polyethlene (LDLPE), very low density poly-
ethlene (VLDPE), polyvinyl chloride (PVC),
flexible polypropylene (fPP), chlorosulfonated
polyethylene (CSPE or Hypalon), and ethyl-
ene propylene diene termonomer (EPPM).
Most manufacturers produce geomembranes
through extrusion or 'calendering. In the
extrusion process, a molten polymer is
stretched into a nonreinforced sheet; extrud-
ed geomembranes are usually made of HDPE
and LLDPE. During the calendering process,
a heated polymeric compound is passed
through a series of rollers. In this process, a
geomembrane can be reinforced with! a
woven fabric or fibers. Calendered geomem-
branes are usually made of PVC and CSPE.
7B-10
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Protecting Ground Water—Designing and Installing liners
What are the thickness recommen-
dations for geomembrane liners?
Geomembranes range in thicknesses from 20
to 120 mil (1 mil = 0.001 in.). A good design
should include a minimum thickness of 30 mil,
except for HDPE liners, which should have a
minimum thickness of 60 mil. These recom-
mended minimum thicknesses ensure that the
liner material will withstand the stress of con-
struction and the weight load of the waste, and
allow adequate seaming to bind separate
geomembrane panels. Reducing the potential
for tearing or puncture, through proper con-
struction and quality control, is essential for a
geomembrane to perform effectively.
What issues should be considered
in the design of a geomembrane
liner?
Several factors to address in the design
include: determining appropriate material
properties and testing to ensure these proper-
ties are met, understanding how the liner will
interact with the intended waste stream,
accounting for all stresses imposed by the
design, and ensuring adequate friction.
Material Properties and Selection
When designing a geomembrane liner, you
should examine several properties of the
geomembrane material in addition to thick-
ness, including: tensile behavior, tear resis-
tance, puncture resistance, susceptibility to
environmental stress cracks, ultraviolet resis-
tance, and carbon black content.
Tensile behavior. Tensile behavior refers to
the tensile strength of a material and its ability
to elongate under strain. Tensile strength is the
ability of a material to resist pulling stresses
without tearing/The tensile properties of a
geomembrane must be sufficient to satisfy the
stresses anticipated during its service life.
These stresses include the self-weight of the
geomembrane and any down drag caused by
waste settlement on side slope liners.
Puncture and tear resistance.
Geomembrane liners can be subject to tearing
during installation due to high winds or han-
dling. Puncture resistance is also important to
consider since geomembranes are often
placed above or below materials that might
have jagged or angular edges. For example,
geomembranes might be installed above a
granular drainage system that includes .gravel.
Susceptibility to environmental stress
cracks. Environmental factors can cause
cracks or failures before a liner is stressed to
its manufactured strength. These imperfec-
tions, referred to as environmental stress
cracks, often occur in areas where a liner has
been scratched or stressed by fatigue. These
cracks can also result in areas where excess
surface wetting agents have been applied. In
surface impoundments, where the geomem-
brane liner has greater exposure to the atmos-
phere and temperature changes, such
exposure can increase the potential for envi-
ronmental stress cracking.
Ultraviolet resistance. Ultraviolet resis-
tance is another factor to consider in the
design of geomembrane liners, especially in
cases where the liner might be exposed to
ultraviolet radiation for prolonged periods of
time. In such cases, which often occur in sur-
face impoundments, ultraviolet radiation can
cause degradation and cracking in the
geomembrane. Adding carbon black or other
additives during the manufacturing process
can increase a geomembranes ultraviolet
resistance. Backfilling over the exposed
geomembrane also works to prevent degrada-
tion due to ultraviolet radiation.
Interactions With Waste
Since the main purpose of a geomembrane
is to provide a barrier and prevent contami-
7B-11
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Protecting Ground Water—Designing and Installing Liners
nants from penetrating through the geomem-
brane, chemical resistance is a critical consid-
eration. Testing for chemical resistance might
be warranted depending on the type, vol-
umes, and characteristics of waste managed
at a particular unit/and the type of geomem-
brane' to be used. An established method for
testing the chemical resistance of geomem-
branes, EPA Method 9090, can be found in
SW-846. ASTM has also adopted standards
for testing the chemical compatibility of vari-
ous geosynthetics, including geomembranes,
with leachates from waste management units.
ASTM D-5747 provides a standard for testing
the chemical compatibility of
geomembranes.7
Stresses Imposed by Liner Design
A liner design should take into account the
stresses imposed on the liner by the design
configuration. These stresses include: the dif-
ferential settlement in foundation soil, strain
requirements at the anchor trench, strain
requirements over long, steep side slopes,
stresses resulting from compaction, and seis-
mic stresses. Often an anchor trench designed
to secure the geomembrane during construc-
tion is prepared along the perimeter of a unit
cell. This action can help prevent the
geomembrane from slipping down the interi-
or side slopes. Trench designs should include
a depth of burial sufficient to hold the speci-
fied length of liner. If forces larger than the
tensile strength of the liner are inadvertently
developed, then the liner could tear. For this
reason, the geomembrane liner should be
allowed to slip or give in the trench after con-
struction to prevent such tearing. To help
reduce unnecessary stresses in the liner de-
sign, it is advisable to avoid using horizontal
seams. For more information on design stress-
es, consult Geosynthetic Guidance for
Hazardous Waste Landfill Cells and Surface
Impoundments (U.S. EPA, 1987).
Designing for Adequate Friction
Adequate friction between the geomem-
brane liner and the soil subgrade, as well as
between any geosynthetic components, is
necessary to prevent extensive slippage or
sloughing on the slopes of a unit. Design
equations for such components should evalu-
ate: 1) the ability of a liner to support its own
-'weight on side slopes, 2) the ability of a liner
to withstand down-dragging during and after
waste placement, 3) the best anchorage con-
figuration' for the liner, 4) the stability of soil
cover on top of a liner, and 5) the stability of
other geosynthetic components, such as geot-
extiles or geonets, on top of a liner. An evalu-
ation of these issues can affect the choice of
geomembrane material, polymer type> fabric
reinforcement, thickness, and texture1 neces-
sary to'achieve the design requirements.
Interface strengths can be significantly
improved by using textured geomembranes.
What issues should be consid-
ered in the construction of a
geomembrane liner?,
When preparing to construct a geomem-
brane liner, you should plan appropriate
shipment and handling procedures, perform
testing prior to construction, prepare; the •
subgrade, consider temperature effects, and
account for wind effects. In addition, you
should select a seaming process, determine a
material for and method of backfilling, and
plan for testing during construction.'
Shipment, Handling, and Site Storage
You should follow quality assurance and
quality control procedures to ensure proper
, handling of geomembranes. Different; types of
geomembrane liners require different) types of
packaging for shipment and storage.(
Typically a geomembrane manufacturer will
provide specific instructions outlining the
7 ASTM D-5747, Practice for Tests to Evaluate the Chemical Resistance of Geomembranes to Liquids.
7B-12
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Protecting Ground Water—Designing and Installing Liners
handling, storage, and construction specifica-
tions for a product. In general, HOPE and
LLDPE geomembrane liners- are packaged in a
roll form, while PVC and CSPE-R liners
(CSPE-R refers to a CSPE geomembrane liner
reinforced with a fabric layer) are packaged in
panels, accordion-folded in two directions,
and placed onto pallets. Whether the liner is
shipped in rolls or panels, you should pro-
vide for proper storage. The rolls and panels
should be packaged so that fork lifts or other
equipment can safely transport them. For
rolls, this involves preparing the roll to have a
sufficient inside diameter so that a fork lift
with a long rod, known as a stinger, can be
used for lifting and moving. For accordion
panels, proper packaging involves using a
structurally-sound pallet, wrapping panels in
treated cardboard or plastic wrapping to pro-
tect against ultraviolet exposure, and using
banding straps with appropriate cushioning.
Once the liners have been transported to the
site, the rolls or panels can be stored until the
subgrade or subbase (either natural soils or
another geosynthetic) is prepared.
Subgrade Preparation
Before a geomembrane liner is installed,
you should prepare the subgrade or subbase.
The subgrade material should meet specified
grading, moisture content, and density
requirements. In the case of a soil subgrade,
it is important to prevent construction equip-
ment used to place the liner from deforming
the underlying materials. If the underlying
materials are geosynthetics, such as geonets
or geotextiles, you should remove all folds
and wrinkles before the liner is placed. For
further information on geomembrane place-
ment, see Chapter 3 of EPA's Technical
Guidance Document: Quality Assurance and
Quality Control for Waste Containment Facilities
(U.S. EPA, 1993c).
Testing Prior to Construction
Before any construction begins, is it recom-
mended that you test both the geomembrane
materials from the manufacturer and the
installation procedures. Acceptance and con-
formance testing is used to evaluate the per-
formance of the manufactured geomembranes.
Constructing test strips can help evaluate how
well the intended construction process and
quality control procedures will work.
Acceptance and conformance testing.
You should perform acceptance and confor-
mance testing on the geomembrane liner
received from the manufacturer to determine
whether the materials meet the specifications
requested. While the specific ASTM test
methods vary depending on geomembrane
type, recommended acceptance and confor-
mance testing for geomembranes includes
evaluations of thickness, tensile strength and
elongation, and puncture and tear resistance
testing, as appropriate. For most geomem-
brane liner types, the recommended ASTM
method for testing thickness is ASTM D-
5199.8 For measuring the thickness of tex-
tured geomembranes, you should use ASTM
D-5994.9 For tensile strength and elongation,
ASTM D-638 is recommended for the HDPE
and LLDPE sheets, while ASTM D-882 and
ASTM D-751 are recommended for PVC and
CSPE geomembranes, respectively.10 Puncture
resistance testing is typically recommended
for HDPE and LLDPE geomembranes using
ASTM D-4833." To evaluate tear resistance
for HDPE, LLDPE, and PVC geomembrane
8 ASTM D-5199, Standard Test Method for Measuring Nominal Thickness of Geotextiles and
Geomembranes.
9 ASTM D-5994, Measuring Core Thickness of Textured Geomembranes.
10 ASTM D-638,* Standard Test Method for Tensile Properties of Plastics.
ASTM D-882, Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.
ASTM D-751, Standard Test Methods.for Coated Fabrics.
" ASTM D-4833, Standard Test Method for Index Puncture Resistance of Geotextiles, Geomembranes,
and Related Products.
7B-13
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Protecting Ground Water—Designing and Installing Liners
liners, the recommended testing method is
ASTM D-1004, Die C.n For CSPE-R
geomembranes, ply adhesion is more of a
concern than tear or puncture resistance and
can be evaluated using ASTM D-413,
Machine Method, Type A.13
Test strips. In preparation for liner place-
ment and field seaming, you should develop
test strips and trial seams as part of the con-
struction process. Construction of such sam-
ples should be performed in a manner that
reproduces all aspects of field production.
Providing an opportunity to test seaming
methods and workmanship helps ensure that
the quality of the seams remains constant
and meets specifications throughout the
entire seaming process.
Temperature Effects
Liner material properties can be altered by
extreme temperatures. High temperatures can
cause geomembrane liner surfaces to stick
together, a process commonly referred to as
blocking. On the other hand, low tempera-
ture can cause the liner to crack when
unrolled or unfolded. Recommended maxi-
mum and minimum allowable sheet tempera-
tures for unrolling or unfolding geomembrane
liners are 50°C (122°F) and 0°C (32°F),
respectively. In addition to sticking and crack-
ing, extreme temperatures can cause geomem-
branes to contract or expand. Polyethylene
geomembranes expand when heated and con-
tract when cooled. Other geomembranes can
contract slightly when heated. Those respon-
sible for placing the liner should take temper-
ature effects into account as they place, seam,
and backfill in the field.
Wind Effects
It is recommended that you take measures
to protect geomembrane liners from wind
damage. Windy conditions can increase the
potential for tearing as a result of uplift. If
wind uplift is a potential problem, panels can
be weighted down with sand bags.
Seaming Processes
Once panels or rolls have been placed,
another critical step involves field-seaming
the separate panels or rolls together. The •
selected seaming process, such as thermal or
chemical seaming, will depend on the chemi-
cal composition of the liner. To ensure the ..
integrity of the seam, you should use the .
seaming method recommended by the manu-
facturer. Thermal seaming uses heat to bond
together the geomembrane panels. Examples
of thermal seaming processes include;extru-
sion welding and thermal fusion (or rnelt
bonding). Chemical seaming involves the use
of solvents, cement, or an adhesive. Chemical
seaming processes include chemical fusion
and adhesive seaming. For more information
on seaming methods, Technical Guidance
Document: Inspection Techniques for the
Fabrication of Geomembrane Field Seams (U.S.
EPA, 1991c), contains a full chapter on each
of the traditional seaming methods and addi-
tional discussion of emerging techniques,
such as ultrasonic, electrical conduction, and
magnetic energy source methods.
Consistent quality in fabricating field
seams is paramount to liner performance.
Conditions that could affect seaming ishould
be monitored and controlled during installa-
tion. Factors influencing seam construction
and performance include: ambient tempera-
ture, relative humidity, wind uplift, changes
in geomembrane temperature, subsurface
water content, type of supporting surface
used, skill of the seaming crew, quality and
consistency of chemical or welding materials,
preparation of liner surfaces to be joined,
moisture at the seam interface, and cleanli-
ness of the seam interface. '
11 ASTM D-1004, Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.:
13 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate. :
7B-14
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Protecting Ground Water—Designing an& Installing Liners
To help control some of these factors, no
more than the amount of sheeting that can be
used during a shift or a work day should be
deployed at one time. To prevent erosion of
the underlying soil surface or washout of the
geomembrane, proper storm water control
measures should be employed. Ambient tem-
perature can become a-concern, if the
geomembrane liner has a high percentage of
carbon black. Although the carbon black will
help to prevent damage resulting from ultra-
violet radiation, because its dark color
absorbs heat, it can increase the ambient tem-
perature of the geomembrane, making instal-
lation more complicated. To avoid surface
moisture or high subsurface water content,
geomembranes should not be deployed when
the subgrade is wet.
Regardless of how well a geomembrane
liner is designed, its ability to meet perfor-
mance standards depends on proper quality
assurance and quality control during installa-
tion. Geomembrane sheets and seams are
subject to tearing and puncture during instal-
lation; punctures or tears can result from con-
tact with jagged edges or underlying materials
or by applying stresses, greater than the
geomembrane sheet can handle. Proper quali-
ty assurance and quality control can help
minimize the occurrence of pinhole or seam
leaks. For example, properly preparing the
underlying layer and ensuring that the gravel
is of an acceptable size reduces the potential
for punctures.
Protection and Backfilling
Geomembrane liners that can be damaged
by exposure to weather or work activities
should be covered with a layer of soil or a
geosynthetic as soon as possible after quality
assurance activities associated with geomem-
brane testing are completed. If the backfill
layer is a soil material, it will typically be a
drainage material like sand or gravel. If the
cover layer is a geosynthetic, it will typically
be a geonet or geocomposite drain placed
directly over the geomembrane. Careful
placement of backfill materials is critical to
avoid puncturing or tearing the geomem-
brane material.
For soil covers, three considerations deter-
mine the amount of slack to be placed in the
underlying geomembrane. These considera-
tions include selecting the appropriate type of
soil, using the proper type of equipment, and
establishing a placement procedure for the
soil. When selecting a soil for backfilling,
characteristics to consider include particle
size, hardness, and angularity, as each of these
can affect the potential for tearing or punctur-
ing the liner. To prevent wrinkling, soil covers
should be placed over the geomembrane in
such a way that construction vehicles do not
drive directly on the liner. Care should be
taken not to push heavy loads of soil over the
geomembrane in a continuous manner.
Forward pushing can cause localized wrinkles
to develop and overturn in the direction of
movement. Overturned wrinkles create sharp
creases and localized stress in the liner and
can lead to premature failure. A recommend-
ed method for placing soil involves continual-
ly placing small amounts of soil or drainage
material and working outward over the toe of
the previously placed material.
Another recommended method involves
placing soil over the liner with a large back-
hoe and spreading it with a bulldozer or sim-
ilar equipment. If a predetermined amount of
slack is to be placed in the geomembrane, the
temperature of the liner becomes an impor-
tant factor, as it will effect the ability of the
liner to contract and expand. Although the
recommended methods for covering
geomembrane liners with soil can take more
time than backfilling with larger amounts of
soil, these methods are designed to prevent
damage caused by covering the liner with too
7B-15
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Protecting Ground Water—Designing and Installing Liners
much soil too quickly. In the long run, pre-
venting premature liner failure can be faster
and more cost-effective than having to repair
a damaged liner.
The types of geqsynthetics that are often
used as protective covering include geotex-
tiles and geonets. Geogrids and drainage geo-
composites can be used for cover soil
reinforcement on slopes. The appendix at the
end of this chapter provides additional infor-
mation on geosynthetic materials. For
geosynthetic protective covers, as with soil
backfilling, to prevent tearing or puncturing,
most construction vehicles should not be
permitted to move directly on the geomem-
brane. Some possible exceptions include
small, 4-wheel, all terrain vehicles or other
types of low ground pressure, equipment.
Even with these types of vehicles, drivers
should take extreme care to avoid move-
ments, such as sudden starts, stops, and
turns, which can damage the geomembrane.
Seaming-related equipment should be
allowed on the geomembrane liner, as long as
it does not damage the liner. Geosynthetic
materials are placed directly on the liner and
are not bonded to it.
Testing During Construction
Testing during construction enables assess-
ment of the integrity of the seams connecting
the geomembrane panels. Tests performed on
the geomembrane seams are categorized as
either destructive or nondestructive.
Destructive testing. Destructive testing
refers to removing a sample from the liner
seam or sheet and performing tests on the
sample. For liner seams, destructive testing
includes shear testing and peel testing; for
liner sheets, it involves tensile testing. While
quality control procedures often require
destructive testing prior to construction, in
order to ensure that the installed seams and
sheets meet performance standards, destruc-
tive testing should be performed during con-
struction also. For increased quality assur-
ance, it is recommended that peel and shear
tests on samples from the installed gepmem-
. brane be performed by an independent labo-
ratory. Testing methods for shear testing, peel
testing, and tensile testing vary for different,
geomembrane liner types.
Determining the number of samples to
take is a difficult step. Taking too few sam-
ples results in a poor statistical representation
of the geomembrane quality. On the other
hand, taking too many samples requires
additional costs and increases the potential
for defects. Defects can result from the repair
patches used to cover the areas from >vhich
samples were taken.
A common sampling strategy is "fixed
increment sampling" where samples are
taken at a fixed increment along the length of
the geomembrane. Increments range from 80
to 300 m (250 to 1,000 ft). The type |of
welding, such as extrusion or fusion jvelding,
used to connect the seams and the type of
geomembrane liner can also help determine
the appropriate sampling interval. For exam-
ple, extrusion seams on HOPE require grind-
ing prior to welding and if extensive grinding
occurs, the strength of the HOPE might
decrease. In such cases, sampling at closer
intervals, such as 90 to 120 m (300 tJD 400
ft), might provide a more accurate descrip-
tion of material properties. If the seam is a
dual hot edge seam, both the inner and outer
seams might need to be sampled and, tested.
If test results for the seam or sheet samples
do not meet the acceptance criteria for the
destructive tests, you should continue jtesting
the area surrounding the rejected sample to •
determine the limits of the low quality seam.
Once the area of low quality has been identi-
fied, dien corrective measures, such as seaming
a cap over the length of the seam or reseaming
the affected area, might be necessary : •
7B-16
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Protecting Ground Water—Designing and Installing Liners
Nondestructive testing. Unlike destruc-
tive tests, which examine samples taken from
the geomembrane liner in the containment
area, nondestructive tests are designed to
evaluate the integrity of larger portions of
geomembrane seams without removing pieces
of the geomembrane for testing. Common
nondestructive testing methods include: the
probe test, air-lance, vacuum box, ultrasonic
methods (pulse echo, shadow, and impedance
planes), electrical spark test, pressurized dual
seam, and electrical resistivity. You should
select the test method most appropriate for
the material and seaming method. If sections
of a seam fail to meet the acceptable criteria
of the appropriate nondestructive test, then
those sections need to be delineated and
patched, reseamed, or retested. If repairing
such sections results in large patches or areas
of reseaming, then destructive test methods
are recommended to verify the integrity of
such pieces.
C Geosynthetic Clay Liners
If a risk evaluation recommended the use -
of a single liner, another option to consider is
a geosynthetic clay liner (GCL). GCLs are fac-
tory-manufactured, hydraulic barriers typical-
ly consisting of bentonite clay (or other very
low permeability materials), supported by
geotextiles or geomembranes held together by
needling, stitching, or chemical adhesives.
GCLs can be used to augment or replace
compacted clay liners or geomembranes, or
they can be used in a composite manner to
augment the more traditional compacted clay
or geomembrane materials. GCLs are typical-
ly used in areas where clay is not readily
available or where conserving air space is an
important factor. As GCLs do not have the
level of long-term field performance data that
geomembranes or compacted clay liners do,
states might request a demonstration that
performance of the GCL design will be com-
parable to that of compacted clay or
geomembrane liners.
What are the mass per unit area
and hydraulic conductivity recom-
mendations for geosynthetic clay
liners?
Geosynthetic clay liners are often designed
to perform the same function as compacted
clay and geomembrane liner components. For
geosynthetic clay liners, you should design
for a minimum of 3.7 kg/m2 (0.75 lb/ft2) dry
weight (oven dried at 105°C) of bentonite
clay with a hydrated hydraulic conductivity
of no more than 5 x 10'9 cm/sec (2 x 10'9
in/sec). It is important to follow manufacturer
specifications for proper GCL installation.
What issues should be consid-
ered in the design of a geosyn-
thetic clay liner?
Factors to consider in GCL design are the
specific material properties needed for the
liner and the chemical interaction or compat-
ibility of the waste with the GCL. When con-
sidering material properties, it is important to
keep in mind that bentonite has a low shear
strength when it is hydrated. Manufacturers
have developed products designed to increase
shear strength.
Materials Selection and Properties
For an effective GCL design, material
properties should be clearly defined in the
specifications used during both manufacture
and construction. The properties that should
be specified include: type of bonds, thick-
ness, moisture content, mass per unit area,
shear strength, and tensile strength. Each of
these properties is described below.
7B-17
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Protecting Ground Water—Designing and Installing Liners
Type of bonds. Geosynthetic clay liners
are available with a variety of bonding
designs, which include a combination of clay,
adhesives, and geomembranes or geotextiles.
The type of adhesives, geotextiles, and
geomembranes used as components of GCLs
varies widely. One type of available GCL
design uses a bentonite clay mixed with an •
adhesive bound on each side by geotextiles.
A variation on this design involves stitching
the upper and lower geotextiles together
through die clay layer. Alternatively another
option is to use a GCL where geotextiles on
each side of adhesive or nonadhesive ben-
tonite clay are connected by needle punch-
ing. A fourth variation uses a clay mixed with
an adhesive bound to a geomembrane on one
side; the geomembrane can be either the
lower or the upper surface. Figure 3 displays
cross section sketches of the four variations
of GCL bonds. While these options describe
GCLs available at the time of this Guide,
emerging technologies in GCL designs
should also be reviewed and considered.
Thickness. The thickness of the various
available GCL products ranges from 4 to 6
mm (160 to 320 mil). Thickness measure-
ments are product dependent. Some GCLs
can be quality controlled for thickness while
others cannot.
Moisture content. GCLs are delivered to
the job site at moisture contents ranging from
5 to 23 percent, referred to as the "dry" state.
GCLs are delivered dry to prevent premature
hydration, which can cause unwanted varia-
tions hi the thickness of the clay component
as a result of uneven swelling.
Stability and shear strength. GCLs
should be manufactured and selected to meet
the shear strength requirements specified in
design plans. In this context, shear strength
is the ability of two layers to. resist forces
moving them in opposite directions. Since
hydrated bentonite clay has low shear
strength, bentonite clay can be placed1
between geotextiles and stitch bonded or
needle- punched to provide additional stabil-
ity. For example, a GCL with geotextiles sup-
ported by stitch bonding has greater internal
resistance to shear in the clay layer than a
GCL without any stitching. Needle-punched
GCLs tend to provide greater resistance than
stitch-bonded GCLs and can also provide
increased friction resistance against an
adjoining layer, because they require the use
of nonwoven geotextiles. Increased friction is
an important consideration on side slppes.
Mass per unit area. Mass per unit area
refers to the bentonite content of a GCL. It is
important to distribute bentonite evenly
throughout the GCL in order to meet [desired
hydraulic conductivity specifications. All
GCL products available in North America use
a sodium bentonite clay with a mass per unit
area ranging from 3.2 to 6.0 kg/m2 (0,66 to
1.2 lb/ft2), as manufactured.
Interaction With Waste
During the selection process for a GCL
liner, you should evaluate the chemical com-
patibility of the liner materials with the types
of waste that are expected to be placed in the
unit. Certain chemicals, such as calcium, can
have an adverse effect on GCLs, resulting in a
loss of liner integrity. Specific information on
GCL compatibilities should be available from
the manufacturer.
What issues should be consid-
ered in the construction of a
geosynthetic clay liner? \
Prior to and during construction, if is rec-
ommended that a qualified professional
should prepare construction specifications for
the GCL. In these specifications, procedures
for shipping and storing materials, as!well as
performing acceptance testing on delivered
7B-18
-------
Protecting Ground Water—Designing and Installing Liners
Figure 3
Four Variations of GCL Bonding Methods
Upper Geotextile
5 mm
(a) Adhesive Bound Clay to Upper and Lower Goetextiles Lower Geotextile
5mm
t
I
•, t— ^ * -~ l^ J £„!»
' Ciay 4-"AdhesBre"of Clay
'^r^':'/A^!^/;r^76^>.x,'.1Ai^r^6^^
(b) Stitch Bonded Clay Between Upper and Lower Goetextiles
4-6 mm
Tftf
*$ Gfey
tfv ryy>
(c) Needle Punched Clay Through Upper and Lower Goetextiles
Upper Geotextile,
Stitch Bonded
in Rows
Lower Geotextile
Upper Geotextile
Needle Punched
Fibers Throughout
Lower Geotextile
t
(d) Adhesive Bound Clay to a Geomembrane
Lower or Upper
Geomembrane
Source: U.S. EPA, 1993c.
7B-19
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Protecting Ground Water—Designing and Installing Liners
materials, should be identified. The specifica-
tions should also address methods for sub-
grade preparation, joining panels, repairing
; sections, and protective backfilling.
Shipment, Handling, and Site
Storage
GCLs are manufactured in widths of
approximately 2 to 5 m (7 to 17 ft) and
: lengths of 30 to 60 m (100 to 200 ft).
: Directly after manufacturing, GCLs are rolled
around a core and covered with a thin plastic
protective covering. This waterproof covering
serves to protect the material from premature
hydratLon. GCLs should be stored at the fac-
tory with these protective coverings. Typical
storage lengths range from a few days to 6
months. To ensure protection of the plastic
covering and the rolls themselves during
loading and unloading, it is recommended -
that qualified professionals specify the equip-
ment needed at the site to lift and deploy the
rolls properly.
To reduce the potential for accidental
damage or for GCLs to absorb moisture at
the site, you should try to arrange for "just-
in-time-delivery" for GCLs transported from
the factory to the field. Even with "just-in-
time-delivery," it might be necessary to store
GCLs for short periods of time at the site.
Often the rolls can be delivered in trailers,
which can then serve as temporary storage.
To help protect the GCLs prior to deploy-
ment, you should use wooden pallets to keep
the rolls off the ground, placing heavy, water-
proof tarps over the GCL rolls to protect
them from precipitation, and using sandbags
to help keep the tarps in place.
Manufacturer specifications should also
indicate how high rolls of GCLs can be
stacked horizontally during storage. Over-
stacking can cause compression of the core
around which the GCL is wrapped. A dam-
aged core makes deployment more difficult
and can lead to other problems. For example,
rolls are sometimes handled by a fork lift
with a stinger attached. The stinger is a long
tapered rod that fits inside the core. If the
core is crushed, the stinger can damage the
liner during deployment.
Acceptance and Conformance
Testing
Acceptance and conformance testing is rec-
ommended either upon delivery of the!GCL
rolls or at the manufacturers facility prior to
delivery. Conformance test samples are,used
to ensure that the GCL meets the project
plans and specifications. GCLs should be
rewrapped and replaced in dry storage areas
immediately after test samples are removed.
Liner specifications should prescribe satnpling
frequencies based on either total area or on
number of rolls. Since variability in GGLs can
exist between individual rolls, it is important
for acceptance and conformance testing to
account for this. Conformance testing can
include the following. ;
Mass per unit area test. The purpose of
evaluating mass per unit area is to ensure an
even distribution of bentonite throughout the
GCL panel. Although mass per unit area
varies from manufacturer to manufacturer, a
typical minimum value for oven dry weight
is 3.7 kg/m2 (0.75 lb/ft2). Mass per unit area
should be tested using ASTM D-5993.>" This
test measures the mass of bentonite per unit
area of GCL. Sampling frequencies should be
determined using ASTM D- 4354.15 ;
Free swell test. Free swell refers to: the
ability of the clay to absorb liquid. Either
ASTM D-5890 or GRI-GCL1, a test method
developed by the Geosynthetic Research
Institute, can be used to evaluate the free
swell of the material.16 .
7B-20
14 ASTM D-5993, Standard Test Method for Measuring Mass per Unit Area of Geosynthetic Clay Oners.
15 ASTM D-4354, Standard Practice for Sampling of Geosynthetics for Testing. .
16 ASTM D-5890, Test Method for Swell Index of Clay Mineral Components of Geosynthetic Clay Liners.
GRI-GCL1, Swell Measurement of the Clay Component of Geosynthetic Clay Liners.
-------
Protecting Ground Water—Designing and Installing Liners
Direct shear test. Shear strength of the
GCLs can be evaluated using ASTM D-5321.17
The sampling frequency for this performance-
oriented test is often based on area, such as
one test per 10,000 m2 (100,000 ft2).
Hydraulic conductivity test. Either ASTM
D-5084 (modified) or GRI-GCL2 will mea-
sure the ease with which liquids can move
through the GCL.18
Other tests. Testing of any geotextiles or
geomembranes should be made on the origi-
nal rolls of the geotextiles or geomembranes
and before they are fabricated into the GCL
product. Once these materials have been
made part of the GCL product, their proper-
ties can change as a result of any needling,
stitching, or gluing. Additionally, any peel
tests performed on needle punched or stitch
bonded GCLs should use the modified ASTM
D-413 with a recommended sampling fre-
quency of one test per 2,000 m2 (20,000 ft2).19
Subgrade Preparation
Because the GCL layer is relatively thin,
the first foot of soil underlying the GCL
should have a hydraulic conductivity of 1 x
10'5 cm/sec or less. Proper subgrade prepara-
tion is essential to prevent damage to the
GCL layer as it is installed. This includes
clearing away any roots or large particles that
could potentially puncture the GCL and its
geotextile or geomembrane components. The
soil subgrade should be of the specified grad-
ing, moisture content, and density required
by the installer and approved by a construc-
tion quality assurance engineer for placement
of the GCL. Construction equipment deploy-
ing the rolls should not deform or rut the soil
subgrade excessively. To help ensure this, the
soil subgrade should be smooth rolled with a
smooth-wheel roller and maintained in a
smooth condition prior to deployment.
Joining Panels
GCLs are typically joined by overlapping
panels, without sewing or mechanically con-
necting pieces together. To ensure proper
joints, you should specify minimum and
maximum overlap distances. Typical overlap
distances range from 150 to 300 mm (6 to 12
in.). For some GCLs, such as needle punched
GCLs with nonwoven geotextiles, it might be
necessary to place bentonite on the area of
overlap. If this is necessary, you should take
steps to prevent fugitive bentonite particles
from coming into contact with the leachate
collection system, as they can cause physical
clogging.
Repair of Sections Damaged During
Liner Placement
During installation, GCLs might incur
some damage to either the clay component or
to any geotextiles or geomembranes. For
damage to geotextile or geomembrane com-
ponents, repairs include patching using geot-
extile or geomembrane materials. If the clay
component is disturbed, a patch made from
the same GCL product should be used to per-
form any repairs.
Protective Backfilling
As soon as possible after completion of
quality assurance and quality control activi-
ties, you should cover GCLs with either a soil
layer or a geosynthetic layer to prevent
hydration. The soil layer can be a compacted
clay liner or a layer of coarse drainage materi-
al. The geosynthetic layer is typically a
17 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or
Geosynthetic and Geosynthetic Friction by the Direct Shear Method.
18 ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous
Materials Using a Flexible Wall Permeameter.
GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs).
19 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.
7B-21
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Protecting Ground Water—Designing and Installing Liners
geomembrane; however, depending on site-
specific designs, it can be a geotextile. As
noted earlier, premature hydration before
covering can lead to uneven swelling, result-
ing in a GCL with varied thickness.
Therefore, a GCL should be covered with its
subsequent soil or geosynthetic layer before a
rainfall or snowfall occurs. Premature hydra-'
lion is less of a concern for GCLs, where the
geosynthetic components are needle punched
or stitch bonded, because these types of con-
nections can better limit clay expansion.
Composite
Liners
A composite liner consists of both a
geomembrane liner and natural soil. The
geomembrane forms the upper component
with the natural soil being the lower compo-
nent. The ususal variations are:
• Geomembrane over compacted clay
liner (GM/CCL).
• Geomembrane over geosynthetic clay
liner (GWGCL).
• Geomembrane over geosynthe'tic clay
liner over compacted clay liner
(GM/GCIVCCL).
A composite liner provides an effective
hydraulic barrier by combining the comple-
mentary properties of the two different liners
into one system. The geomembrane provides a
highly impermeable layer to maximize leachate
collection and removal. The natural soil liner
serves as a backup in the event of any leakage
from the geomembrane. With a composite
liner design, you should construct a leachate
collection and removal system above the
geomembrane. Information on design and con-
struction of leachate collection and removal
systems is provided in Section V below.
What are the thickness and
hydraulic conductivity recom-
mendations for composite liners?
Each component of the composite liner
should follow the recommendations for
geomembranes, geosynthetic clay liners, and
compacted clay liners described earlier.
Geomembrane liners should have a mini-
mum thickness of 30 mil, except for HDPE
liners, which should have a- minimum; thick-
ness of 60 mil. Similarly, compacted clay lin-
ers should be at least 2 feet thick and are
typically 2 to 5 feet thick. For compaqted
clay liners and geosynthetic clay liners, you
should use materials with maximum ,
hydraulic conductivities of 1 x 10'7 cnj/sec (4
x 10"8 in/sec) and 5 x 10* cm/sec (2 x'lO'9
in/sec), respectively.
What issues should be consid-
ered in the design of a compos-
ite liner?
As a starting point, you should follqw the
design considerations discussed previously for
single liners. In addition, to achieve the bene-
fits of a combined liner system, you should
install the geomembrane to ensure good con-
tact with the compacted clay layer. The uni-
formity of contact between the geomembrane
and the compacted clay layer helps control
the flow of leachate. Porous material, such as
drainage sand or a geonet, should notbe
placed between the geomembrane and the
clay layer. Porous materials will create,a layer
of higher hydraulic conductivity, which will
increase the amount of leakage below any
geomembrane imperfection.
You should consider the friction or| shear
strength between a compacted clay layer and
a geomembrane. The fiiction or shear stress
at this surface is often low and can form a
weak plane on which sliding can occur.
7B-22
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Protecting Ground Water—Designing and Installing Liners
ASTM D-5321 provides a test method for
determining the friction coefficient of soil and
geomembranes.20 When using bentonite-
amended soils, it is important to account for
how the percentage of bentonite added and
the degree of saturation affect interface fric-
tion. To provide for stable slopes, it is impor-
tant to control both the bentonite and
moisture contents. A textured geomembrane
can increase the friction with the clay layer
and improve stability.
What issues should be consid-
ered in the construction of a
composite liner?
To achieve good composite bonding, the
geomembrane and the compacted clay layer
should have good hydraulic contact. To
improve good contact, you should smooth-
roll the surface of the compacted clay layer
using a smooth, steel-drummed roller and
remove any stones. In addition, you should
place and backfill the geomembrane so as to
minimize wrinkles.
The placement of geomembranes onto a
compacted clay layer poses a challenge,
because workers cannot drive heavy
machines over the clay surface without
potentially damaging the compacted clay
component. Even inappropriate footwear can
leave imprints in the clay layer. It might be
possible to drive some types of low ground
pressure equipment or small, 4-wheel, all ter-
rain vehicles over the clay surface, but drivers
should take extreme care to avoid move-
ments, such as sudden starts, stops, and
turns, that could damage the surface. To
avoid damaging the clay layer, it is recom-
mended that you unroll geomembranes by
lifting the rolls onto jacks at a cell side and
pulling down on the geomembrane manually.
Also, the entire roll with its core can be
unrolled onto the cell (with auxiliary support
using ropes on embankments).
To minimize desiccation of the compacted
clay layer, you should place the. geomem-
brane over the clay layer as soon as possible.
Additional cover materials should also be
placed over the geomembrane. Exposed
geomembranes absorb heat, and high temper-
atures can dry out and crack an underlying
compacted clay layer. Daily cyclic changes in
temperature can draw water from the clay
layer and cause this water to condense on the
underside of the geomembrane. This with-
drawal of water can lead to desiccation crack-
ing and potential interface stability concerns.
IV. Double Liners
(Primary and
Secondary Lined
Systems)
In a double-lined waste management unit,
there are two distinct liners—one primary
(top) liner and one secondary (bottom) liner.
Each liner might consist of compacted clay, a
geomembrane, or a composite (consisting of a
geomembrane and a compacted clay layer or
GCL). Above the primary liner, it is recom-
mended that you construct a leachate collec-
tion and removal system to collect and convey
liquids out of the waste management unit and
to control the depth of liquids above the pri-
mary liner. In addition, you should place a
leak detection, collection, and removal system
between the primary and secondary liner.
This leak detection system will provide leak
warning, as well as collect and remove any
liquid or leachate that has escaped the prima-
ry liner. See section V below for information
on the design of leachate collection and
removal systems and leak detection, collec-
tion, and removal systems.
J ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or
Geosynthetic and Geosynthetic Friction by the Direct Shear Method.
7B-23
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Protecting Ground Water—Designing and Installing Liners
What are the thickness and ,
hydraulic conductivity recom-
mendations for double liners?
Each component of the double liner
should follow the recommendations for
geomembranes, compacted clay liners, or
composite liners described earlier.
Geomembrane liners should have a minimum
thickness of 30 mil, except for HDPE liners,
which should have a minimum thickness of
60 mil. Similarly, compacted clay liners
should be at least 2 feet thick and are typical-
ly 2 to 5 feet thick. For compacted clay liners
and geosynthetic clay liners, use materials
with maximum hydraulic conductivities of 1
x 10'7 cm/sec (4 x 10* in/sec) and 5 x 10'9
cm/sec (2 x 10-" in/sec), respectively.
What issues should be consid-
ered in the design and construc-
tion of a double liner?
Like composite liners, double liners are
composed of a combination of single liners.
When planning to design and construct a
double liner, you should consult the sections
on composite and single liners first. In addi-
tion, you should consult the sections on
leachate collection and removal systems and
leak detection systems.
V. Leachate
Collection and
Leak Detection
Systems
One of the most important functions of a
waste management unit is controlling
leachate and preventing contamination of the
underlying ground water. Both leachate col-
lection and removal systems and leak detec-
tion systems serve this purpose. You should
consult with the state agency too determine if
such systems are required. The primary func-
tion of a leachate collection and removal sys-
tem is to collect and convey leachate out of a
unit and to control the depth of leachate
above a liner. The primary function of a leak
detection system is to detect leachate that has
escaped the primary liner. A leak detection
system refers to drainage material located
below the primary liner and above a sec-
ondary liner (if there is one); it acts as a sec-
ondary leachate collection and removal
system. After the leachate has been removed
and collected, a leachate treatment system
might be incorporated to process the leachate
and remove harmful constituents.
The information in this section on leachate
collection and leak detection systems is
applicable if the unit is a landfill or a waste
pile. Surface impoundments, which manage
liquid wastes, usually will not have leachate
collection and removal systems unless; they
will be closed in-place as landfills; they might
have leak detection systems to detect liquid
wastes that have escaped the primary liner.
Leachate collection or leak detection systems
generally are not used with land application.
A. Leachate Collection
System
A typical leachate collection system
includes a drainage layer, collection pipes, a
removal system, and a protective filter, layer.
Leachate collection systems are designed to
collect leachate for, treatment or alternate dis-
posal and to reduce the buildup of leachate
above the liner system. Figure 4 shows a
cross section of a typical leachate collection
system showing access to pipes for cleaning.
7B-24
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Protecting Ground Water—Designing and Installing Liners
Figure 4
Typical Leachate Collection System
Final grade
Concrete base •
Sweep bend and cap
Manhole Casing
Solid pipe
Recompacted
clay
Sweep bend
• Perforated pipe
• Pipe backfill
Source: U.S. EPA, 1995b
What are the recommendations
for leachate collection and
removal systems?
You should design a leachate collection and
removal system to maintain less than 30 cm
(12 in.) depth of leachate, or "head," above
the liner if granular soil or a geosynthetic
material is used. The reason for maintaining
this level is to prevent excessive leachate from
building up above the liner, which could
jeopardize the liner's performance. This
should be the underlying factor guiding the
design, construction, and operation of the
leachate collection and removal system.
You should design a leachate collection
and removal system capable of controlling the
estimated volume of leachate. To determine
potential leachate generation, you should use
water balance equations or models. The most
commonly used method to estimate leachate
generation is EPA's Hydrogeologic Evaluation
of Landfill Performance (HELP) model.21 This
model uses weather, soil, and waste manage-
ment unit design data to determine leachate
generation rates.
What issues should be consid-
ered in the design of a leachate
collection and removal system?
You should design a leachate collection
and removal system to include the following
elements: a low-permeability base, a high-
permeability drainage layer, perforated
leachate collection pipes, a protective filter
layer, and a leachate removal system. During
31 Available on the CD-ROM version of the Guide, as well as from the U.S. Army Corps of Engineers Web
site
7B-25
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Protecting Ground Water—Designing and Installing Liners
design, you should consider the stability of
the base, the transmissivity of the drainage
layers, and the strength of the collection
pipes. It is also prudent to consider methods
to minimize physical, biological, and chemi-
cal clogging within'the system.
Low-Permeability Base ,
A leachate collection system is placed over
the unit's liner system. The bottom liner
should have a minimum slope of 2 percent to
allow the leachate collection system to gravity
flow to a collection sump. This grade is nec-
essary to provide proper leachate drainage
throughout the operation, closure, and post-
closure of the unit. Estimates of foundation
soil settlement should include this 2 percent
grade as a post-settlement design.
High-Permeability Drainage Layer
A high-permeability drainage layer consists
of drainage materials placed directly over the
low-permeability base, at the same minimum
2 percent grade. The drainage materials can
be either granular soil or geosynthetic materi-
als. For soil drainage materials, a maximum of
12 inches of materials with a hydraulic con-
ductivity of at least 1 x 10'2 cm/sec (4 x 10'3
in/sec) is recommended. For this reason, sand
and gravel are the most common soil materi-
als used. If the drainage layer is going to
incorporate sand or gravel, it should be
demonstrated that the layer will have suffi-
cient bearing capacity to withstand the waste
load of the full unit. Additionally, if the waste
management unit is designed on grades of 15
percent or higher, it should be demonstrated
that the soil drainage materials will be stable
on the steepest slope in the design.
Geosynthetic drainage materials such as
geonets can be used in addition to, or in place
of, soil materials. Geonets promote rapid
transmission of liquids and are most effective
when used in conjunction with a filter'layer
or geotextile to prevent clogging. Geonets
consist of integrally connected parallel sets of
plastic ribs overlying similar sets at various
angles. Geonets are often used on the side
walls of waste management units because of
their ease of installation. Figure 5 depipts a
typical geonet material configuration. j
The most critical factor involved with using
geonets in a high-permeability drainage layer
is the material's ability to transmit fluids
under load. The flow rate of a geonet dan be
evaluated by ASTM D-4716.22 Several addi-
tional measures for determining the transmis-
sivity of geonets are discussed in the Solid
Waste Disposal Facility Criteria: Technical
Manual (U.S. EPA, 1993b). .;
Perforated Leachate Collection Pipes
Whenever the leachate collection system is
a natural soil, a perforated piping system
should be located within it to rapidly trans-
mit the leachate to a sump and removal sys-
tem. Through the piping system, leachate
flows gravitationally to a low point where the
sump and removal system is located. The
design of perforated leachate collection pipes,
therefore, should consider necessary flow
rates, pipe sizing, and pipe structural i
strength. After estimating the amount jof
leachate using the HELP model or a similar
water balance model, it is possible to calcu-
late the appropriate pipe diameter and spac-
ing. For the leachate collection system
design, you should select piping material that
can withstand the anticipated weight of the
waste, construction and operating equipment
stresses, and foundation settling. Most
leachate collection pipes used in modirn
waste management units are constructed of
HDPE. HDPE pipes provide great structural
strength, while allowing significant chemical
resistance to the many constituents found in
leachate. PVC pipes are also used in Waste
ASTM D-4716, Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane Flow) of
Geotextiles and Geotextile Related Products. . . , .,
7B-26
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Protecting Ground Water—Designing and Installing Liners
Figure 5
Typical Geonet Configuration
Channel
management units, but they are not as chemi-
cally resistant as HDPE pipes.
Protective Filter Layer
To protect the drainage layer and perforat-
ed leachate collection piping from clogging,
you should place a filter layer over the high-
permeability drainage layer. To prevent waste
material from moving into the drainage layer,
the filter layer should consist of a material
with smaller pore space than the drainage
layer materials or the perforation openings in
the collection pipes. Sand and geotextiles are
the two most common materials used for fil-
tration. You should select sand that allows
adequate flow of liquids, prevents migration
of overlying solids or soils into the drainage
layer, and minimizes clogging during the ser-
vice life. In designing the sand filter, you
should consider particle size and hydraulic
conductivity. The advantages of using sand
materials include common usage, traditional
design, and durability.
Any evaluation of geotextile materials
should address the same concerns but with a
few differences. To begin with, the average
pore size of the geotextile should be large
enough to allow the finer soil particles to pass
but small enough to
retain larger soil parti-
cles. The number of
openings in the geotex-
tile should be large
enough that, even if
some of the openings
clog, the remaining
openings will be suffi-
cient to pass the design
flow rate. In addition to
pore size, geotextile fil-
ter specifications should
include durability
requirements. The
advantages of geotextile
materials include vertical space savings and
easy placement. Chapter 5 of Technical
Guidance Document: Quality Assurance and
Quality Control for Waste Containment Facilities
(U.S. EPA, 1993c) offers guidance on protec-
tion of drainage layers.
Leachate Removal System
Leachate removal often involves housing a
sump within the leachate collection drainage
layer. A sump is a low point in the liner con-
structed to collect leachate. Modern waste
management unit sumps often consist of pre-
fabricated polyethylene structures supported
on a steel plate above the liner. Especially
with geomembrane liners, the steel plate
serves to support the weight of the sump and
protect the liner from puncture. Gravel filled
earthen depressions can serve as the sump.
Reinforced concrete pipe and concrete floor-
ing also can be used in place of the polyethyl-
ene structure but are considerably heavier.
To remove leachate that has collected in
the sump, you should use a submersible
pump. Ideally, the sump should be placed at
a depth of 1 to 1.5 m (3 to 5 ft) to allow
enough leachate collection to prevent the
pump from running dry. You should consider
7B-27
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Protecting Ground Water—Designing and Installing Liners
installing a level control, backup pump, and
warning system to ensure proper sump oper-
ation. Also consider using a backup pump as
an alternate to the primary pump and to
assist it during high flow periods. A warning
system should be used to indicate pump mal-
function.
Standpipes, vertical pipes extending
through the waste and cover system, offer
one method of removing leachate from a
sump without puncturing the liner.
Alternatively, you can remove leachate from a
sump using pipes that are designed to pene-
trate the liner. When installing pipe penetra-
tions through the liner, you should proceed
with extreme caution to prevent any liner
damage that could result in uncontained
leachate. Both of these options rely on gravity
to direct leachate to a leachate collection
pond or to an external pumping station.
Minimizing Clogging
Leachate collection and removal systems
are susceptible to physical, biological, and
chemical clogging. Physical clogging can
occur through the migration of finer-grained
materials into coarser-grained materials, thus
reducing the hydraulic conductivity of the
coarser-grained material. Biological clogging
can occur through bacterial growth in the
system due to the organic and nutrient mate-
rials in leachate. Chemical clogging can be
caused by chemical precipitates, such as cal-
cium carbonates, causing blockage or cemen-
tation of granular drainage material.
Proper selection of drainage and filter mate-
rials is essential to minimize clogging in the
high-permeability drainage layer. Soil and geo-
textile filters can be used to minimize physical
clogging of both granular drainage material
and leachate collection pipes. When placed
above granular drainage material, these filters
can also double as an operations layer to pre-
vent sharp waste from damaging the liner or
leachate collection and removal systems. To
minimize chemical and biological clogging for
granular drainage material, the best procedure
is to keep the interstices of the granular
drainage material as open as possible.;
The leachate collection pipes are also sus-
ceptible to similar clogging. To prevent this,
you should incorporate measures intp the
design to allow for routine pipe cleaning,
using either mechanical or hydraulic meth-
ods. The cleaning components can include
pipes with a 15 cm (6 in) minimum diameter
to facilitate cleaning; access located at major
pipe .intersections or bends to allow for
inspections and cleaning; and valves,: ports,
or other appurtenances to introduce biocides
and cleaning solutions. Also, you should
check that the design does not include wrap-
ping perforated leachate collection pipes
directly with geotextile filters. If the geotex-
tile becomes clogged, it can block flow into
the pipe. i
B. Leak Detection System
The leak detection system (LDS) is also
known as the secondary leachate collection
and removal system. It uses the same
drainage and collection components as the
primary leachate collection and removal sys-
tem and identifies, collects, and removes any
leakage from the primary system. The LDS
should be located directly below the .primary
liner and^above the secondary liner.
What are the recommendations
for leak detection systems?
The LDS should be designed to assess the
adequacy of the primary liner against
leachate leakage; it should cover botji the
bottom and side walls of a waste mahage-
ment unit. The LDS should be designed to
collect leakage through the primary layer and
transport it to a sump within 24 hours.
7B-28
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Protecting Ground Water—Designing and Installing Liners
The LDS should allow for monitoring and
collection of leachate escaping the primary
liner system. You should monitor the LDS on
a regular basis. If the volume of leachate
detected by the LDS appears to be increasing
or is significant, you should consider a closer
examination to determine possible remedia-
tion measures. A good rule of thumb is that if
the LDS indicates a seepage level greater than
20 gallons per acre per day the system might
need closer monitoring or remediation.
C. Leachate Treatment
System
Once the leachate has been removed from
the unit .and collected, you should consider
taking measures to characterize the leachate
in order to ensure proper management. There
are several methods of disposal for leachate,
and the treatment strategy will vary according
to the disposal method chosen. Leachate dis-
posal options include discharging to or
pumping and hauling to a publicly owned
treatment works or to an onsite treatment
system; treating and discharging to the envi-
ronment; land application; and natural or
mechanical evaporation.
When discharging to or pumping and
hauling leachate to a publicly owned treat-
ment wprks, a typical treatment strategy
includes pretreatment. Pretreatment could
involve equalization, aeration, sedimentation,
pH adjustment, or metals removal.23 If the
plan for leachate disposal does not involve a
remote treatment facility, pretreatment alone
usually is not sufficient.
There are two categories of leachate treat-
ment, biological and physical/chemical. The
most common method of biological treatment
is activated sludge. Activated sludge is a "sus-
pended-growth process that uses aerobic
microorganisms to biodegrade organic contam-
inants in leachate."24 Among physical/chemical
treatment techniques, the carbon absorption
process and reverse osmosis are the two most
common methods. Carbon absorption uses
carbon to remove dissolved organics from
leachate and is very expensive. Reverse osmo-
sis involves feeding leachate into a tubular
chamber whose wall acts as a synthetic mem-
brane, allowing water molecules to pass
through but not pollutant molecules, thereby
separating clean water from waste constituents.
What are the recommendations
for leachate treatment systems?
You should review all applicable federal
and state regulations and discharge standards
to determine which treatment system will
ensure long-term compliance and flexibility
for the unit. Site-specific factors will also play
a fundamental role in determining the proper
leachate treatment system. For some facilities,
onsite storage and treatment might not be an
option due to space constraints. For other
facilities, having a nearby, publicly owned
treatment works might make pretreatment
and discharge to the treatment works an
attractive alternative.
VI-. Construction
Quality
Assurance and
Quality Control
Even the best unit design will not translate
into a structure that is protective of human
health and the environment, if the unit is not
properly constructed. Manufacturing quality
assurance and manufacturing quality control
(MQA and MQC) are also important issues
for the overall project; however, they are dis-
cussed only briefly here since they are pri-
marily the responsibility of a manufacturer.
Nonetheless, it is best to select a manufactur-
23 Arts, Tom. "Alternative Approaches For Leachate Treatment." World Wastes.
24 Ibid.
7B-29
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Protecting Ground Water—Designing and Installing Liners
er who incorporates appropriate quality
assurance and quality control (QA and QC)
mechanisms as part of the manufacturing
process. The remainder of this section pro-
vides a general description of the compo-
nents of a construction quality assurance and
construction quality control (CQA and CQC)
program for a project. CQA and CQC are
critical factors for waste management units.
They are not interchangeable, and the dis-
tinction between them should be kept in
mind when preparing plans. CQA is third
party verification of quality, while CQC con-
sists of in-process measures taken by the con-
tractor or installer to maintain quality. You
should establish clear protocols for identify-
ing and addressing issues of concern
throughout every stage of construction.
What is manufacturing quality
assurance?
The desired characteristics of liner materi-
als should be specified in the unit's contract
with the manufacturer. The manufacturer
should be responsible for certifying that mate-
rials delivered conform to those specifications.
MQC implemented to ensure such confor-
mance might take the form of process quality
control or computer-aided quality control. If
requested, the manufacturer should provide
information on the MQC measures used,
allow unit personnel or engineers to visit the
manufacturing facility, and provide liner sam-
ples for testing. It is good practice for the
manufacturer to have a dedicated individual
in charge of MQC who would work with unit
personnel in these areas.
What is construction quality
assurance?
CQA is a verification tool employed by the
facility manager or regulatory agency, consist-
ing of a planned series of observations and
tests designed to ensure that the filial prod-
uct meets project specifications.'CQA; testing,
often referred to as acceptance inspection,
provides a measure of the final product quali-
ty and its conformance with project plans
and specifications. Performing acceptance
inspections routinely, as portions of the pro-
ject become complete, allows early detection
and correction of deficiencies, before they
become large and costly.
On routine construction projects, CQA is
normally the concern of the facility manager
and is usually performed by an independent,
third-party testing firm. The independence of
the testing firm is important, particularly
when a facility manager has the capacity to
perform the CQA activities. Although ithe
MQC MQA, CQC and CQA
Manufacturing quality control
(MQC) is measures taken by the manu-
facturer to ensure compliance with, the
material and workmanship specifications
of the facility manager. i
Manufacturer quality assurance
(MQA) is measures taken by facility per-
sonnel, or by an impartial party brought
in expressly for the purpose, to deter- ^
mine if the manufacturer is in compli-
ance with the specifications of the facility
manager , ''
Construction quality control (CQC)
is measures taken by the installer or con-
tractor to ensure compliance with the
installation specifications of the facility
manager ' ~ y
Construction quality assurance
(CQA) is measures taken by facility per-
sonnel, or by an impartial party brought ,
in expressly for the purpose, to deter-
mine if the installer or contractor is in
^
compliance with thetinstallation specifi-
cations of the facility "manager
7B-30
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Protecting Ground Water—Designing and Installing Liners
facility's in-house CQA personnel might be
registered professional engineers, a perception
of misrepresentation might arise if CQA is not
performed by an independent third party.
The independent party should designate a
CQA officer and fully disclose any activities
or relationships that the officer has with the
facility manager that might impact his or her
impartiality or objectivity. If such activities or
relationships exist, the CQA officer should
describe actions that have been or can be
taken to avoid, mitigate, or neutralize the
possibility they might affect the CQA officer's
objectivity. State regulatory representatives
can help evaluate whether these mechanisms
are sufficient to ensure acceptable CQA.
What is construction quality
control?
CQC is an ongoing process of measuring
and controlling the characteristics of the prod-
uct in order to meet manufacturer's or project
specifications. CQC inspections are typically
performed by the contractor to provide an in-
process measure of construction quality and
conformance with the project plans and speci-
fications, thereby allowing the contractor to
correct the construction process if the quality
of the product is not meeting the specifica-
tions and plans. Since CQC is a production
tool employed by the manufacturer of materi-
als and by the contractor installing the materi-
als at the site, the Guide does not cover CQC
in detail. CQC is performed independently of
CQA. For example, while a geomembrane
liner installer will perform CQC testing of
field seams, the CQA program should require
independent testing of those same seams by a
third-party inspector.
How can implementation of CQA
and CQC plans be ensured?
When preparing to design and construct a
waste management unit, regardless of design,
you should develop CQA and CQC plans
customized to the project. To help the project
run smoothly, the CQA plan should be easy
to follow. You should organize the CQA plan
to reflect the sequence of construction and
write it in language that will be familiar to an
average field technician. For a more detailed
discussion of specific CQA and CQC activi-
ties recommended for each type of waste
management unit, you should consult
Technical Guidance Document: Quality
Assurance and Quality Control for Waste •
Management Containment Facilities (U.S. EPA,
1993c). This document provides information
to develop comprehensive QA plans and to
carry out QC procedures at waste manage-
ment units.
CQA and CQC plans can be implemented
through a series of meetings and inspections,
which should be documented thoroughly.
Communication among all parties involved in
design and construction of a waste manage-
ment unit is essential to ensuring a quality
product. You should define responsibility and
authority in written QA and QC plans and
ensure that each party involved understands
its role. Pre-construcdon meetings are one
way to help clarify roles and responsibilities.
During construction, meetings can continue
to be useful to help resolve misunderstandings
and to identify solutions to unanticipated
problems that might develop. Some examples
of typical meetings during the course of any
construction project include pre-bid meetings,
resolution meetings, pre-construction meet-
ings, and progress meetings.
7B-31
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Protecting Ground Water—Designing and Installing Liners
A. Compacted Clay Liner
Quality Assurance and
Quality Control
Although manufacturing quality control
and quality assurance are often the responsi-
bility of the materials manufacturer, in the
case of soil components, manufacturing and
construction quality control testing can be
the responsibility of the facility manager. The
CQA and CQC plans should specify proce-
dures for quality assurance and quality con-
trol during construction of the compacted
clay liners.
How can implementation of QA
and QC be ensured for a com-
pacted clay liner?
QC testing is typically performed by the
contractor on materials used in construction
of the liner. This testing examines material
properties such as moisture content, soil den-
sity, Atterberg limits, grain size, and laborato-
ry hydraulic conductivity. Additional testing
of soil moisture content, density, lift thick-
ness, and hydraulic conductivity helps ensure
that the waste management unit has been
constructed in accordance with the plans and
technical specifications.
CQA testing for soil liners includes the
same tests described for QC testing in the
paragraph above. Generally, the tests are per-
formed less frequently. CQA testing is per-
formed by an individual or an entity
independent of the contractor. Activities of
the CQA officer are essential to document
quality of construction. The responsibilities
of the CQA officer and his or her staff might
include communicating with the contractor;
interpreting and clarifying project drawings
and specifications with the designer, facility
manager, and contractor; recommending
acceptance or rejection by the facility manag-
er of work completed by the construction
contractor; and submitting blind samples,
such as duplicates and blanks, for analysis by
the contractor's testing staff or independent
laboratories. . ;
You should also consider constructing a
test pad prior to full-scale construction as a
CQA tool. As described earlier in the section
on compacted clay liners, pilot construction
or test fill of a small-scale test pad can be
used to verify that the soil, equipment, and
construction procedures can produce a liner
that performs according to the construction
drawings and specifications.
Specific factors to examine or test during
construction of a test fill include: preparation.
and compaction of foundation material to the
required bearing strength; methods of con-
trolling uniformity of the soil material; com-
pactive effort, such as type of equipment and
number of passes needed to achieve required
soil density and hydraulic conductivity; and
lift thickness and placement procedures
needed to achieve uniformity of density
throughout a lift and prevent boundary
effects between lifts or between placements in
the same lift. Test pads can also provide a
means to evaluate the ability of different
types of soil to meet hydraulic conductivity
requirements in the field. In addition :to
allowing an opportunity to evaluate material
performance, test pads also allow evaluation
of the skill and competence of the construc-
tion team, including equipment operators,
and QC specialists. . ,
B. Geomembrane Liner
Quality Assurance and
Quality Control
As with the construction of soil linbrs,
installation of geomembrane liners should be
in conformance with a CQA and CQC plan.
The responsibilities of the CQA personnel for
the installation of the geomembrane are gen-
78-32
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Protecting Ground Water—Designing and Installing Liners
erally the same as the responsibilities for the
construction of a compacted clay liner, with
the addition of certain activities including
observations of the liner storage area and lin-
ers in storage, and handling of the liner as the
panels are positioned in the cell.
Geomembrane CQA staff should also observe
seam preparation, seam overlap, and materi-
als underlying the liner.
How can implementation of QA
and QC be ensured for a
geomembrane liner?
Prior to installation, you should work with
the geomembrane manufacturer to ensure the
labeling system for the geomembrane rolls is
clear and logical, allowing easy tracking of the
placement of the rolls within the unit. It is
important to examine the subgrade surface
with both the subgrade contractor and the liner
installer to ensure it conforms to specifications.
Once liner installation is underway, CQA
staff might be responsible for observations of
destructive testing conducted on scrap test
welds prior to seaming. Geomembrane CQA
staff might also be responsible for sending
destructive seam sampling to an independent
testing laboratory and reviewing the results for
conformance to specifications. Other observa-
tions for which the CQA staff are typically
responsible include observations of all seams
and panels for defects due to manufacturing
and handling, and placement and observations
of all pipe penetrations through a liner.
Test methods, test parameters, and testing
frequencies should be specified in the CQA
plan to provide context for any data collect-
ed. It is prudent to allow for testing frequen-
cy to change, based on the performance of
the geomembrane installer. If test results indi-
cate poor workmanship, you should increase
testing. If test results indicate high quality
installation work, you can consider reducing
testing frequencies. When varying testing fre-
quency, you should establish well-defined
procedures for modifying testing frequency. It
is also important to evaluate testing methods,
understand the differences among testing
methods, and request those methods appro-
priate for the material and seaming method
be used. Nondestructive testing methods are
preferable when possible to, help reduce the
number of holes cut into the geomembrane.
Geomembrane CQA staff also should docu-
ment the results of their observations and pre-
pare reports indicating the types of sampling
conducted and sampling results, locations of
destructive samples, locations of patches,
locations of seams constructed, and any prob-
lems encountered. In some cases, they might
need to prepare drawings of the liner installa-
tion. Record drawing preparation is frequently
assigned to the contractor, to a representative
of the facility manager, or to the engineer. You
should request complete reports from any
CQA staff and the installers. To ensure com-
plete CQA documentation, it is important to
maintain daily CQA reports and prepare
weekly summaries.
C. Geosynthetic Clay Liner
Quality Assurance and
Quality Control
Construction quality assurance for geosyn-
thetic clay liners is still a developing area; the
GCL industry is continuing to establish stan-
dardized quality assurance and quality con-
trol procedures. The CQA recommendation
for GCLs can serve as a starting point. You
should check with the GCL manufacturer and
installer for more specific information.
7B-33
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Protecting Ground Water—Designing and Installing Liners
How can implementation of QA
and QC be ensured for a geosyn-
thetic day liner?
It is recommended that you develop a
detailed CQA plan, including product speci-
fications; shipping, handling, and storage
procedures; seaming methods; and placement
of overlying material. It is important to work
with the manufacturer to verify that the
product meets specifications. Upon receipt of
the GCL product, you should also verify that
it has arrived in good condition.
During construction, CQA staff should
ensure that seams are overlapped properly
and conform to specifications. CQA staff
should also check that panels, not deployed
within a short period of time, are stored
properly. In addition, as overlying material is
placed on the GCL, it is important to restrict
vehicle traffic directly on the GCL. You
should prohibit direct vehicle traffic, with the
exception of small, 4-wheel, all terrain vehi-
cles. Even with the small all-terrain vehicles,
drivers should take extreme care to avoid
movements, such as sudden starts, stops, and
turns, which can damage the GCL.
As part of the CQA documentation, it is
important to maintain records of weather
conditions, subgrade conditions, and GCL
panel locations. Also, you should document
any repairs that were necessary or other
problems identified and addressed.
D. Leachate Collection
System Quality
Assurance and Quality
Control
Leachate collection system CQC should be
performed by the contractor. Similar activi-
ties should be performed for CQA by an
independent party acting on behalf of the
facility manager. The purpose of leachate col-
lection system CQA is to document that the
system is constructed in accordance with
design specifications.
How can implementation df QA
and QC be ensured for a
leachate collection system?
Prior to construction, CQA staff should
inspect all materials to confirm that they meet
the construction plans and specifications.
These materials include: geonets; geotextiles;
pipes; granular material; mechanical, electri-
cal, and monitoring equipment; concrete
forms and reinforcements; and prefabricated
structures such as sumps and manholes. The
leachate collection system foundation, jeither a
geomembrane or compacted clay liner,1 should
also be inspected, upon its completion, to
ensure that it has proper grading and ig free
of debris and liquids. ' ;
During construction, CQA:staff should
observe and document, as appropriate, the
placement and installation of pipes, filter lay-
ers, drainage layers, geonets and geoteixtiles,
sumps, and mechanical and electrical equip-
ment. For pipes, observations might include
descriptions of pipe bedding material, j quality
and thickness, as well as the total area' cov-
ered by the bedding material. Observations
of pipe installations should focus on the loca-
tion, configuration, and grading of the pipes,
as well as the quality of connections at joints.
For granular filter layers, CQA activities
might include observing and documenting
material thickness and quality during place-
ment. For granular drainage layers, CQA
might focus on the protection of underlying
liners, material thickness, proper overlap
with filter fabrics and geonets (if applicable),
and documentation of any weather condi-
tions that might affect the overall perfor-
mance of the drainage layer. For geonets and
7B-34
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Protecting Ground Water—Designing arid Installing Liners
other geosynthetics, CQA observations
should focus on the area of coverage and lay-
out pattern, as well as the overlap between
panels. For geonets, CQA staff might want to
make sure that the materials do not become
clogged by granular material that can be car-
ried over, as a result of either wind or runoff
during construction.
Upon completion of construction, each
component should be inspected to identify
any damage that might have occurred during
its installation or during construction of
another component. For example, a leachate
collection pipe can be crushed during place-
ment of a granular drainage layer. Any dam-
age that does occur should be repaired, and
the repairs should be documented in the
CQA records.
7B-35
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Protecting Ground Water—Designing and Installing Liners
Designing arid Installing Liners Activity List
D Review the recommended location considerations and operating practices for the unit.
D Select appropriate liner type—single, composite, or double liner—or in-situ soils, based on risk
characterization.
Q Evaluate liner material properties and select appropriate clay, geosynthetic, or combination of mate-
rials; consider interactions of liner and soil material with waste.
D Develop a construction quality assurance (CQA) plan defining staff roles and responsibilities and
specifying test methods, storage procedures, and construction protocols.
D Ensure a stable in-situ soil foundation, for nonengineered liners.
D Prepare and inspect subgrade for engineered liners. '
D Work with manufacturer to ensure protective shipping, handling, and storage of all materials.
D Construct a test pad for compacted clay liners.
D Test compacted clay liner material before and during construction.
D Preprocess clay material to ensure proper water content, remove oversized particles, and add soil
amendments, as applicable.
D Use proper lift thickness and number of equipment passes to achieve adequate compaction.
D Protect clay material from drying and cracking.
D Develop test strips and trial seams to evaluate geomembrane seaming method.
D Verify integrity of factory and field seams for geomembrane materials before and during construction.
D Backfill with soil or geosynthetics to protect geomembranes and geosynthetic clay liners during
construction. ;
D Place backfill materials carefully to avoid damaging the underlying materials. j
D Install geosynthetic clay liner with proper overlap.
Q Patch any damage that occurs during geomembrane or geosynthetic clay liner installation.
D Design leachate collection and removal system to allow adequate flow and to minimize clogging;
include leachate treatment and leak detection systems, as appropriate.
D Document all CQA activities, including meetings, inspections, and repairs.
7B-36
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Protecting Ground Water—Designing and Installing Liners,
Resources
ASTM D-413. 1993- Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.
ASTM D-422. 1990. Standard Test Method for Particle-Size Analysis of Soils.
ASTM D-638. 1991. Standard Test Method for Tensile Properties of Plastics.
ASTM D-698. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using Standard
Effort (12,400 ft-lbfrTt3 (600 kN-m/m3)).
ASTM D-751. 1989. Standard Test Methods for Coated Fabrics. ,
ASTM D-882. 1991. Standard Test Methods for Tensile Properties of Thin Plastic Sheeting.
ASTM D-1004. 1990. Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.
ASTM D-1557. 1991. Test Method for Laboratory Compaction Characteristics of Soil Using Modified
Effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)).
ASTM D-4318. 1993. Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of
Soils.
ASTM D-4354. 1989. Standard Practice for Sampling of Geosynthetics for Testing.
ASTM D-4716. 1987. Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane
Flow) of Geotextiles and Geotextile Related Products.
ASTM D-5084. 1990. Standard Test Method for Measurement of Hydraulic Conductivity of Saturated
Porous Materials Using a Flexible Wall Permeameter.
ASTM D-5199. 1991. Standard Test Method for Measuring Nominal Thickness of Geotextiles and
Geomembranes.
ASTM D-5261. 1992. Standard Test Method for Measuring Mass per Unit Area of Geotextiles.
ASTM D-5321. 1992. Standard Test Method for Determining the Coefficient of Soil and Geosynthetic
or Geosynthetic and Geosynthetic Friction by the Direct Shear Method.
7B-37
-------
Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Bagchi, A. 1994. Design, Construction, and Monitoring of Landfills.
Berg, R., and L. Well. 1996. A Position Paper on: The Use of Geosynthetic Barriers in Nonhazardous
Industrial Waste Containment.
Berger, E. K. and R. Berger. 1997. The Global Water Cycle.
Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.
Boulding, J.R. 1995. Practical Handbook of Soil, Vadose Zone, and Ground Water Contamination:
Assessment, Prevention and Remediation. Lewis Publishers.
Brandt, R.C. and K.S. Martin. 1996. The Food Processing Residual Management Manual. September.
Daniel, D.E., and R.M. Koemer. 1991. Landfill Liners from Top to Bottom. Civil Engineering. December.
Daniel, D.E., and R.M. Koerner. 1993. Technical Guidance Document: Quality Assurance and Quality
Control for Waste Containment Facilities. Prepared for U.S. EPA. EPA60Q-R-93-182.
Daniel, D.E., and R.M. Koemer. 1995. Waste Containment Facilities: Guidance for Construction, Quality
Assurance and Quality Control of Liner and Cover Systems.
Evanylo, G.K. and W L. Daniels. 1996. The Value and Suitability of Papermill Sludge and Sludge
Compost as a Soil Amendment and Soilless Media Substitute. Final Report. The Virginia Department of
Agriculture and Consumer Services, P.O. Box 1163, Room 402, Richmond, VA. April.
Federal Test Method Standard 101C. 1980. Puncture Resistance and Elongation Test (1/8 Inch Radius
Probe Method). ;
Fipps, G. 1995. Managing Irrigation Water Salinity in the Lower Rio Grande Valley,
Geosynthetic Research Institute. 1993. GRI-GCL1, Swell Measurement of the Clay Component of GCLs.
Geosynthetic Research Institute. 1993. GRI-GCL2, Permeability of Geosynthetic Clay Liners (GCLs).
7B-38
-------
Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Idaho Department of Health and Welfare. 1988. Guidelines for Land Application of Municipal and
Industrial Wastewater. March.
Koerner, R.M. 1994. Designing with Geosynthetics, Third Edition.
McGrath, L, and P. Creamer. 1995. Geosynthetic Clay Liner Applications in Waste Disposal
Facilities.
McGrath, L., and P. Creamer. 1995. Geosynthetic Clay Liner Applications. Waste Age. May.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guidance for Land
Application of Wastewater Sludge in Michigan. March.
Michigan Department of Natural Resources, Waste Characterization Unit. 1991. Guide to Preparing
a Residuals Management Plan. March.
Minnesota Pollution Control Agency. 1993. Land Treatment of Landfill Leachate. February.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Nutrient Management
Software: Proceedings from the Nutrient Management Software Workshop. NRAES-100. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1996. Animal Agriculture and
the Environment: Nutrients, Pathogens, and Community Relations. NRAES-96. December.
Northeast Regional Agricultural Engineering Cooperative Extension. 1993. Utilization of Food
Processing Residuals. Selected Papers Representing University, Industry, and Regulatory
Applications. NRAES-69. March.
North Carolina Cooperative Extension Service. 1994. Soil facts: Careful Soil Sampling - The Key to
Reliable Soil Test Information. AG-439-30.
Oklahoma Department of Environmental Quality. Title 252. Oklahoma Administrative Code,
Chapter 647. Sludge and Land Application of Wastewater.
Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and Landfills:
Design and Evaluation.
Smith, M.E., S. Purdy, and M. Hlinko. 1996. Some Do's and Don'ts of Construction Quality
Assurance. Geotechnical Fabrics Report. January/February.
7B-39
-------
Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
Spellman, F. R. 1997. Wastewater Biosolids to Compost. ;
Texas Water Commission. 1983. Industrial Solid Waste Management Technical Guideline No. 5: Land
Application. December.
Tsinger, L. 1996. Chemical Compatibility Testing: The State of Practice. Geotechnical Fabrics Report.
October/November. ,
University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources. 1991.
Guidelines for Soil Sampling. G91-1000-A. February.
U.S. EPA. 2001. Technical Resource Document: Assessment and recommendations for Improving the
Performance of Waste Containment Systems. Draft.
U.S. EPA. 1996a. Issue Paper on Geosynthetic Clay Liners (GCLs). .
U.S. EPA. 1996b. Report of 1995 Workshop on Geosynthetic Clay Liners. EPA600-R-96-149. June.
U.S. EPA. 1995a. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule. EPA832-B-93-
005. September. ,
U.S. EPA. 1995b. Decision Maker's Guide to Solid Waste Management. Volume II. EPA530-R-95-023.
U.S. EPA. 1995c. Laboratory Methods for Soil and Foliar Analysis in Long-Term Environmental
Monitoring Programs. EPA600-R-95-077.
U.S. EPA. 1995d. Process Design Manual: Land Application of Sewage Sludge and Domestic Septage.
EPA625-R-95-001. September.
U.S. EPA. 1995e. Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage.
EPA625-R-95-002. September.
U.S. EPA. 1994a. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA832-R-93-003.:
September. :
U.S. EPA. 1994b. -Biosolids Recycling: Beneficial Technology for a Better Environment. EPA832-R-94-
009. June.
U.S. EPA. 1994c. Guide to Septage Treatment and Disposal. EPA625-R-94-002. September. ;
7B-40
-------
Protecting Ground Water—-Designing anil Instating liners
Resources (cant.)
U.S. EPA. 1994d. Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirements
of the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503. EPA831-B-93-
002b. December.
U.S. EPA. 1994e. Seminar Publication: Design, Operation, and Closure of Municipal Solid Waste
Landfills. EPA625-R-94-008.
U.S. EPA. 1993a. Domestic Septage Regulatory Guidance: A Guide to the EPA 503 Rule. EPA832-B-92-
005. September.
U.S. EPA. 1993b. Solid Waste Disposal Facility Criteria: Technical Manual. EPA530-R-93-017.
U.S. EPA. 1993c. Technical Guidance Document: Quality Assurance and Quality Control for Waste
Containment Facilities. EPA600-R-93-182.
U.S. EPA. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA625-R-92-013.
December.
U.S. EPA. 1991a. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers
EPA625-4-91-025.
U.S. EPA. 1991b. Seminar Publication: Site Characterization for Subsurface Remediation EPA625-4-91-
026.
U.S. EPA. 199Ic. Technical Guidance Document: Inspection Techniques for the Fabrication of
Geomembrane Field Seams. EPA530-SW-91-051.
U.S. EPA. 1990. State Sludge Management Program Guidance Manual. October.
U.S. EPA. 1989a. Seminar Publication: Requirements for Hazardous Waste Landfill Design,
Construction, and Closure. EPA625-4-89-022.
U.S. EPA. 1989b. Seminar Publication: Corrective Action: Technologies and Applications EPA625-4-89-
020.
U.S. EPA. 1988. Lining of Waste Containment and Other Impoundment Facilities. EPA600-2-88-052.
U.S. EPA. 1987. Geosynthetic Guidance for Hazardous Waste Landfill Cells and Surface Impoundments
EPA600-2-87-097.
7B-41
-------
Protecting Ground Water—Designing and Installing Liners
Resources (cont.)
U.S. EPA, 1986a. Project Summary: Avoiding Failure of Leachate Collection and Cap Drainage Systems.
EPA600-S2-86-058. .
U.S. EPA. 1986b. Test Methods for Evaluating Solid Waste: Physical/Chemical Methods. EPASW-846.
U.S. EPA. 1983. Process Design Manual for Land Application of Municipal Sludge. EPA625-l-83r016.
October. :
U.S. EPA, U.S. Army Corps of Engineers, U.S. Department of Interior, and U.S. Department of ;
Agriculture. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA625-1-81-
013. October.
U.S. EPA. 1979. Methods for Chemical Analysis of Water and Wastes. EPA600-4-79-020. '
Viessman Jr., W and MJ. Hammer. 1985. Water Supply and Pollution Control. 4th ed. ;
Washington State Department of Ecology. 1993. Guidelines for Preparation of Engineering Reports for
Industrial Wastewater Land Application Systems. Publication #93-36. May.
Webber, M.D. and S.S. Sing. 1995. Contamination of Agricultural Soils. In Action, D.E and LJ,;
Gregorich, eds. The Health of Our Soils.
Wisconsin Department of Natural Resources. 1996, Chapter NR 518: Landspreading of Solid Wast;e. April.
7B-42
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Protecting Ground Water—Designing and Installing Liners
Appendix
Geosynthetic Materials25
Geotexf/Ves
Geotextiles form one of the two largest
group of geosynthetics. Their rise in growth
during the past fifteen years has been nothing
short of awesome. They are .indeed textiles in
the traditional sense, but consist of synthetic
fibers rather than natural ones such as cotton,
wool, or silk. Thus biodegradation is not a
problem. These synthetic fibers are made into
a flexible, porous fabric by standard weaving
machinery or are matted together in a ran-
dom, or nonwoven, manner. Some are also
knit. The major point is that they are porous
to water flow across their manufactured plane
and also within their plane, but to a widely
varying degree. There are at least 80 specific
application areas for geotextiles that have been
developed; however, the fabric always per-
forms at least one of five discrete functions:
1. Separation
2. Reinforcement
3. Filtration
4. Drainage
5. Moisture barrier (when impregnated)
Geogrids
Geogrids represent a rapidly growing seg-
ment within the geosynthetics area. Rather
than being a woven, nonwoven or knit textile
(or even a textile-like) fabric, geogrids are
plastics formed into a very open, gridlike
configuration (i.e., they have large apertures).
Geogrids are either stretched in one or two
directions for improved physical properties or
made on weaving machinery by unique
methods. By themselves, there are at least 25
application areas, however, they function
almost exclusively as reinforcement materials.
Geonets
Geonets, called geospacers by some, con-
stitute another specialized segment within the
geosynthetic area. They are usually formed by
a continuous extrusion of parallel sets of
polymeric ribs at acute angles to one another.
When the ribs are opened, relatively large
apertures are formed into a netlike configura-
tion. Their design function is completely
within the drainage area where they have
been used to convey fluids of ail types.
Geomembranes
Geomembranes represent the other largest
group of geosynthetics and in dollar volume
their sales are probably larger than that of
geotextiles. Their growth has been stimulated
by governmental regulations originally enact-
ed in 1982. The materials themselves are
"impervious" thin sheets of rubber or plastic
material used primarily for linings and covers
of liquid- or solid-storage facilities. Thus the
primary function is always as a liquid or
vapor barrier. The range of applications, how-
ever, is very great, and at least 30 individual
applications in civil engineering have been
developed.
Geosynthetic Clay Liners
Geosynthetic clay liners (or GCLs) are the
newest subset within geosynthetic materials.
They are rolls of factory fabricated thin layers
of bentonite clay sandwiched between two
geotextiles or bonded to a geomembrane.
Structural integrity is maintained by needle
punching, stitching or physical bonding.
They are seeing use as a composite compo-
25 Created by Geosynthetic Research Institute. Accessed from the Internet on October 16, 2001 at
.
7B-43
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Protecting Ground Water—Designing and Installing Liners
nent beneath a geomembrane or by them-
selves as primary or secondary liners.
Geopipe (aka Buried Plastic Pipe)
Perhaps the original geosynthetic material
still available today is buried plastic pipe. This
"orphan" of the Civil Engineering curriculum.
was included due to an awareness that plastic
pipe is being used in all aspects of geotechni-
cal, transportation, and environmental engi-
neering with little design and testing
awareness. This is felt to be due to a general
lack of formalized training. The critical nature
of leachate collection pipes coupled with high
compressive loads makes geopipe a bona-fide
member of the geosynthetics family. The func-
tion is clearly drainage.
Geocomposites
A geocomposite consists of a combination
of geotextile and geogrid; or geogrid and
geomembrane; or geotextile, geogrid, and
geomembrane; or any one of these three
materials with another material (e.g.,;
deformed plastic sheets, steel cables, :or steel
anchors). This exciting area brings out the
best creative efforts of the engineer, manufac-
turer, and contractor. The application areas
are numerous and growing steadily. The
major functions encompass the entire range
of functions listed for geosynthetics discussed
previously: separation, reinforcement, filtra-
tion, drainage, and liquid barrier. '.
"Geo-Others"
The general area of geosynthetics has
exhibited such innovation that many systems
defy categorization. For want of a be'tter
phrase, geo-others, describes items such as
threaded soil masses, polymeric anchors, and
encapsulated soil cells. As with geocpmpos-
ites their primary function is product-depen-
dent and can be any of the five major
functions of geosynthetics. • !
7B-44
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Part IV
Protecting Ground Water
Chapter 7: Section C
Designing A Land Application Program
-------
Contents
I. Identifying Waste Constituents for'Land Application 1 7C-2
II. Evaluating Waste Parameters j 7C"4
A. Total Solids Content •'; 7C~4
B.pH... : : • t 7C'5
C. Biodegradable Organic Matter • 7C"6
D.Nutrients : .; 7C"6
E. Metals r 7C~8
E Carbon-to-Nitrogen Ratio - r 7C'8
G. Soluble Salts : r 7C~9
H. Calcium Carbonate Equivalent 1 7C-11
I. Pathogens • ; 7C"U
III. Measuring Soil Properties : ,- •- •••• ••••• i 7C-12
IV. Studying the Interaction of Plants and Microbes with Waste i 7C-14
A. Greenhouse and Field Studies \ 7C-15
B. Assessing Plant and Microbial Uptake Rates ;.. ...... - -i 7C-16
C. Effects of Waste on Plant and Microbe Growth • 7C-17
D. Grazing and Harvesting Restrictions - •• i 7C-18
V. Considering Direct Exposure, Ecosystem Impacts, & Bioaccumulation of Waste j 7C-18
VI. Accounting for Climate ! 7C-19
VII. Calculating An Agronomic Application Rate , f 7C-19
VULMonitoring f 7C-21
IX. Odor Controls r 7C~22
Designing a Land Application Program Activity List <• 7C-23
~t(~ 94
Resources -. i "--•"
Tables:
Table 1: Summary of Important Waste Parameters i 7C-4
Table 2: Salinity Tolerance of Selected Crops , 7C-10
Table 3: EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils : 7C-11
Figures: ;
Figure 1: A Recommended Framework for Evaluating Land Application , 7C-3
Figure 2: The Nitrogen Cycle :- i 7C"7
-------
Protecting Ground Water—Designing A Land Application Program
Designing A Land Application Program
This chapter will help you:
• Assess the risks associated with waste constituents when consider-
ing application directly to the land as a soil amendment, or for
treatment, or disposal.
• Account for the designated ground-water constituents identified in
Chapter 7, Section A—Assessing Risk, as well as other waste para-
meters such as soil properties and plant and microbial interactions.
• Evaluate the capacity of the soil, vegetation, and microbial life to
safely assimilate the waste when developing an application rate.
Some of the benefits of land application
include:
and application can be a beneficial
'and practical method for treating and
disposing of some wastes. Because
land application does not rely on lin-
^rs to contain waste, however, there
are some associated risks. With proper planning
and design, a land application program can
meet waste management and land preservation
goals, and avoid negative impacts such as nox-
ious odors, long-term damage to soil, and
releases of contaminants to ground water, sur-
face water, or the air. This chapter describes and
recommends a framework for addressing a vari-
ety of waste parameters, in addition to the con-
stituents outlined in Chapter 7, Section
A—Assessing Risk,1 and other factors such as
soil properties and plant and microbial nutrient
use2 that can affect the ability of the land to
safely assimilate directly applied waste.
Successful land application programs address
the interactions among all these factors.
Biodegradation of waste. If a waste
stream contains sufficient organic
material, plants and microorganisms
can significantly biodegrade the
waste, assimilating its organic compo-
nents into the soil. After allowing suf-
ficient time for assimilation of the
waste, more waste can be applied to a
given site without significantly
increasing the total volume of waste at
the site. This is in contrast to landfills
and waste piles, in which waste accu-
mulates continually and generally
does not biodegrade quickly enough
to reduce its volume significantly.
Inclusion of liquids. Land applica-
tion units can accept bulk, non-con-
tainerized liquid waste. The water
1 The constituents incorporated in IWEM, including the heavy metals and synthetic organic chemicals,
typically have little or no agricultural value and can threaten human health and the environment even
in small quantities. The term "waste parameters" as used in this section refers to some additional con-
stituents such as nitrogen and biodegradable organic matter and other site-specific properties such as
pH, that can have considerable agricultural significance and that can significantly impact human health
and the environment.
2 40 CFR Part 503 specifies requirements for land application of sludge from municipal sewage treatment
plants. The Part 503 regulations apply to sewage sludge (now generally referred to as "biosolids") or
mixtures of sewage sludge and industrial process wastes, not to industrial wastes alone. Some of the
specifications in Part 503, for example those concerning pathogens, might be helpful in evaluating land
application of industrial wastes. For mixtures of sewage sludge and industrial waste, the ground-water
and air risk assessments and the framework laid out in the Guide can help address constituents that are
not covered under the Part 503 regulations.
7C-1
-------
Protecting Ground Water—Designing A Land Application Program
content of some liquid wastes make
them desirable at land application
sites in arid climates. When managing
liquid waste, land application can
reduce the need for expensive dewa-
tering processes.
• Improvement of soil. Applying waste
directly to land can improve soil qual-
ity if the waste contains appropriate
levels of biodegradable organic matter
and nutrients. Nutrients can improve
the chemical composition of the soil
to the extent that it can better support
vegetation, while biodegradable organ-
ic matter can improve its physical
properties and increase its water
retention capacity. This potential for
chemical and physical improvements
through land application have led to
its use in conditioning soil for agricul-
tural use.
Figure 1 outlines a framework for evaluat-
ing land application. This framework incorpo-
rates both the ground-water risk assessment
methodology recommended in Chapter 7,
Section A-Assessing Risk, as well as the other
waste parameters and factors important to
land application.
I. Identifying
Waste
Constituents for
Land Application
If a waste leachate contains any of the con-
stituents covered in the IWEM ground-water
model, you should first check with a federal,
state, or other regulatory agency to see if the
waste constituents identified in the waste are
covered by any permits, MOUs, or other agree-
ments concerning land application. The Guide
does not supersede or modify conditions estab-
lished in regulatory or other binding mecha-
nisms, such as MOUs or agreements.3
Some wastes might be designated by state
or local regulators as essentially equivalent to
a manufactured product or raw material. Such
designations usually are granted only, when
use of the designated waste would not present
a greater environmental and health risk than
would use of the manufactured or raw materi-
al it replaces. Equivalence designations are
included in the category of "other agreements"
above. If there are no designated ground-water
constituents other than those on which the
designation is based, then the guidelines
described in this chapter can help you to
determine an appropriate application rate.
If the constituent(s) identified in tjhe waste
is not currently covered under an agreement,
IWEM or another site-specific model can help
you determine whether land application of the
constituent(s) will be protective of ground
water. In some cases, pollution prevention or
treatment can lower constituents levels so that
a waste can be land applied. In other cases,
land application might not be feasible. In this
event, you should pursue other waste manage-
ment options. If your modeling results indi-
cate that the constituents can be land applied,
then the guidelines described in this; chapter
can once again help you to determine an
appropriate application rate.
Your modeling efforts should consider both
the direct exposure and ecosystem pathways.
These pathways are extremely important in
land application since waste is placed on the
land and attenuated by the natural environ-
ment rather than contained by an engineered
structure. '
7C-2
EPA has signed agreements with states, industries, and individual sites concerning land application. One
example is EPAs Memorandum of Understanding (MOU) between the American Forest and Paper
Association (AFPA) and the U.S. EPA Regarding the Implementation of the Land Application Agreements
Among AF&PA Member Pulp and Paper Mills and the U.S. EPA, January 1994. For more information on
this MOU contact either AFPAs Director of Industrial Waste Programs at 111 19th Street, N.W.,!
Washington, D.C. 20036 or EPA's Director of the Office of Pollution Prevention and Toxics. :
-------
Protecting Ground Water—Designing A Land Application Program
Figure 1. A Recommended Framework for Evaluating Land Application
Perform waste characterization
• Ground-water constituents
• Other waste parameters
Identify waste constituents
Follow terms of
permit, MOD,
or agreement
Yes
Are all IWEM constituents identified in the waste
covered by permit, MOU, or other agreement?*
Evaluate waste
parameters
Measure soil
parameters
Study interaction of
plants and microbes
with waste
Consider direct expo-
sure, ecosystem
impacts, and bioaccu-
mulation of waste
Account for climate
' Calculate agronomic
application rate
Evaluate application
rate. If waste stream
exceeds rate, consider
additional management
measures
Yes
No
Evaluate IWEM constituents identified in
the waste to determine whether land appli-
cation is protective of ground water using
IWEM or other risk assessment tool
No
Constituents should not be land applied
and you should treat wastes and
reassess land application potential or
identify other disposal options
* All constituents should have been
assessed and shown not to be a risk, or are
. addressed by constituents directly covered
by MOU, permit, or other agreement.
7C-3
-------
Protecting Ground Water—Designing A Land Application Program
II. Evaluating
Waste
Parameters
In addition to the ground-water con-
stituents designated in Chapter 7, Section
A-Assessing Risk, you should evaluate the
wastes total solids content, pH, biodegradable
matter, pathogens, nutrients, metals, carbon
to nitrogen ratio, soluble salts, and calcium
carbonate equivalent when considering land
application. These parameters provide the
basis for determining an initial waste applica-
tion rate and are summarized in Table 1. After
the initial evaluation, you should sample and
characterize the waste on a regular basis and
after process changes that might affect waste
characteristics to help determine whether you
should change application practices or con-
sider other waste management options,.
A. Total Solids Content
Total solids content indicates the ratio of
solids to water in a waste. It includes jboth
suspended and dissolved solids, and ijs usual-
ly expressed as a percentage of the waste.
Table 1
Summary of Important Waste Parameters
Waste Parameter ; --Significance , ',•_ >;,,-,; :, .' :•_,•'--,. ' / ,: - ; ;-|
-------
Protecting Ground Water—Designing A Land Application Program
Total solids content depends on the type of
waste, as well as whether the waste has been
treated prior to land application. If waste is
dried, composted, dewatered, thickened, or
conditioned prior to land application, water
content is decreased, thereby increasing the
total solids content (for some dry, fine, partic-
ulate wastes, such as cement kiln dust, condi-
tioning might involve adding water).4
Understanding the total solids content will
help you develop appropriate storage and
handling procedures and establish an applica-
tion rate. Total solids content also can affect
your choice of application method and equip-
ment. Some methods, such as spray irriga-
tion, might not work effectively if the solids
content is too high. If it is low, meaning liq-
uid content is correspondingly high, waste
transportation costs could increase. If the
total solids content of the waste is expected
to vary, you can select equipment to accom-
modate materials with a range of solids con-
tent. For example, selecting spreaders that
will not clog if the waste is slightly drier than
usual will help operations run more efficient-
ly and reduce equipment problems.
B. pH
A wastes pH is a measure of its acidic or
alkaline quality. Most grasses and legumes, as
well as many shrubs and deciduous trees,
grow best in soils with a pH range from 5.5
to 7.5. If a waste is sufficiently acidic or alka-
line5 to move soil pH out of that range, it can
hamper plant growth. Acidic waste promotes
leaching of metals, because most metals are
more soluble under acidic conditions than
neutral or alkaline conditions. Once in solu-
tion, the metals would be available for plant
uptake or could migrate to ground water.
Alkaline conditions inhibit movement of
most metals. Extreme alkalinity, where pH is
greater than 11, impairs growth of most soil
Source: Ag-Chem Equipment Co., Inc.
Reprinted with permission
Source: Ag-Chem Equipment Co., Inc.
Reprinted with permission
Source: Ag-Chem Equipment Co., Inc.
Reprinted with permission
microorganisms and can increase the mobility
of zinc, cadmium, and lead.
Aqueous waste with a pH of 2 or less or a
pH of 12.5 or more meets the definition of
hazardous waste under federal regulations (40
CFR 261.22(a)). If the pH of a waste makes it
too acidic for land application, you can con-
sider adjusting waste pH before application.
Lime is often used to raise pH, but other
materials are also available. The pH is also
important to consider when developing waste
handling and storage procedures.
4 Some states consider composted materials to no longer be wastes. Consult with the regulatory agency
for applicable definitions.
5 A pH of 7 is neutral. Materials with pH less than 7 are acidic, while those with pH greater than 7 are
alkaline.
7C-5
-------
Protecting Ground Water—Designing A Land Application Program
C Biodegradable Organic
Matter
Wastes containing a relatively high percent-
age of biodegradable organic matter have
greater potential as conditioners to improve
the physical properties of soil. The percentage
of biodegradable organic matter in soil is
important to soil fertility, as organic matter
can add nutrients; serve as an absorption and
retention site for nutrients; and provide chem-
ical compounds, such as chelating agents, that
help change nutrients into more plant-avail-
able forms. The content of biodegradable
organic matter is typically expressed as a per-
centage of sample dry weight.
Biodegradable organic matter also influ-
ences soil characteristics. Soils with high
organic matter content often have a darker
color (ranging from brown to black), increased
cation exchange capacity—capacity to take up
and give off positively charged ions—and
greater water holding capacity. Biodegradable
organic matter also can help stabilize and
improve the soil structure, decrease the density
of the material, and improve aeration in the
soil. In addition, organic nutrients are less like-
ly than inorganic nutrients to leach.
How can biodegradable organic
matter affect the waste applica-
tion rate?
While organic materials, provide a signifi-
cant source of nutrients fan plant growth,
decomposition, rates can vary significantly
among materials-. Fooxi processing residues, for
example, generally decompose faster than
denser organic materials, such as wood chips.
It is important to account for the decomposi-
tion rate when determining the volume, rate
and frequency of waste application. Loading
the soil with too much decomposing organic
matter (such as by applying new waste before
a previous application of slowly decomposing
waste has broken down) can induce nitrogen
deficiency (see section D. below) or lead to
anaerobic conditions.
D. Nutrients
Nitrogen, phosphorus, and potassium are
often referred to as primary or macro-Jiutri-
ents and plants use them in large amounts.
Plants use secondary nutrients, including sul-
fur, magnesium, and calcium, in intermediate
quantities. They use micronutrients, includ-
ing iron, manganese, boron, chlorine, 'zinc,
copper, and molybdenum, in very small
quantities. Land application is often used to
increase the supply of these nutrients, espe-
cially the primary nutrients, in an effort to
improve plant growth. .
Nutrient levels are key determinants of
application rates. Excessive soil nutrient lev-
els, caused by high waste application: rates,
can be phytotoxic or result in contamination
of ground water, soil, and surface water.
Nutrient loading is dependent on nutrient
levels in both the waste and the soil, making
characterization of the soil, as well as of the
waste, important. ;
Nitrogen. Nitrogen content is often the
primary factor determining whether a: waste
is agriculturally suitable for land application,
and, if so, at what rate to apply it. Nitrogen
deficiency is detrimental to the most basic
plant processes,, as nitrogen is an essential
element for photosynthesis. Sufficient; nitro-
gen promotes healthy growth and imparts a
dark green color in vegetation. Lack of nitro-
gen can be identified by stunted plant growth
and pale green or yellowish colored vegeta-
tion. Extreme nitrogen deficiency can • cause
plants to turn brown and die. On the,other
extreme, excessive nitrogen levels can, result
in nitrate leaching, which can contaminate
ground-water supplies. . ;
7G6
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Protecting Ground Water—Designing A Land Application Program
Although nitrate poses the greatest threat
to ground water, nitrogen occurs in a variety
of forms including ammonium, nitrate,
nitrite, and organic nitrogen. These forms
taken together are measured as total nitrogen.
You should account for the ever-occurring
nitrogen transformations that take place in
the soil before and after waste is applied.
These transformations are commonly
described as the nitrogen cycle and are illus-
trated below in Figure 2.
Figure 2. The Nitrogen Cycle
Phosphorus. Phosphorus plays a role in
the metabolic processes and reproduction of
plants. When soil contains sufficient quanti-
ties of phosphorus, root growth and plant
maturation improve. Conversely, phospho-
rus-deficient soils can cause stunted plant
growth. Excessive phosphorus can lead to
inefficient use of other nutrients and, at
extreme levels, zinc deficiency. High phos-
phorus usage on crops and its associated
runoff into surface water bodies has increased
the biological productivity of surface waters
by accelerating eutrophication, which is the
natural aging of lakes or streams brought on
by nutrient enrichment.6 Eutrophication has
been identified as the main cause of impaired
surface water quality in the United States.
Potassium. Potassium is an essential.
nutrient for protein .synthesis and plays an
important role in plant hardiness and disease
tolerance. In its ionic form (K*), potassium
helps to regulate, the hydration of plants. It
also works, in the ion transport system across
cell membranes and activates many, plant
enzymes. Like other nutrients, symptoms of
deficiencies include yellowing, burnt or
dying leaves, as well as stunted plant growth.
Symptoms of potassium deficiency also, in
certain plants, can include
reduced disease resistance and
winter hardiness.
How can I take nutrient
levels into account?
You should develop a nutri-
ent management plan that
accounts for the amount of
nitrogen, phosphorus, and
potassium being supplied by all
sources at a site. The U.S.
Department of Agriculture,
Natural Resources Conservation
Service has developed a conser-
vation practice standard
"Nutrient Management" Code 590 that can
be used as the basis for your nutrient man-
agement plan. The purpose of this standard
is to budget and supply nutrients for plant
production, to properly utilize manure or
organic by-products as a plant nutrient
source, to minimize agricultural nonpoint
source pollution of surface and ground-water
resources, and to maintain or improve the
physical, chemical, and biological condition
of the soil. Updated versions of this standard
can be obtained from the Internet at
.
Nitrogen is generally the-most limiting
nutrient in crop production systems and is
added to the soil environment in the greatest
U.S. Department of Agriculture, Agricultural Research Service. Agricultural Phosphorus and
Eutrophication, 1999. Washington, DC.
7C-7
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Protecting Ground Water—Designing A Land Application Program
amount of any of the plant nutrients. If, how-
ever, waste application rates are based solely
on nitrogen levels, resulting levels of other
nutrients such as phosphorus and potassium
can exceed crop needs or threaten ground
water or surface water bodies. You should
avoid excessive nutrient levels by monitoring
waste concentrations and soil buildup of
nutrients and reducing the application rate as
necessary, or by spacing applications to allow
plant uptake between applications. Your
local, state, or regional agricultural extension
service might have already developed materi-
als on or identified software for nutrient
management planning. Consult with them
about the availability of such information.
Northeast Regional Agricultural Engineering
Services (NRAES) Cooperative Extension, for
example, has compiled information on nutri-
ent management software programs.7
E. Metals
A number of metals are included in IWEM
for evaluating ground-water risk. Some metals,
such as zinc, copper, and manganese, are
essential soil micronutrients for plant growth.
These are often added to inorganic commercial
fertilizers. At excessive concentrations, howev-
er, some of these metals can be toxic to
humans, animals, and plants. High concentra-
tions of, copper, nickel, and zinc, for example,
can cause phytotoxicity or inhibit plant
growth. Also, the uptake and accumulation of
metals in plants depends on a variety of plant
and soil factors, including pH, biodegradable .
organic matter content, and cation exchange
capacity. Therefore, it is important to evaluate
levels of these metals in waste, soil, and plants
from the standpoint of agricultural significance
as well as health and environmental risk.
How can I determine acceptable
metal concentrations?
The Tier I and II ground-water models can
help you identify acceptable metals concentra-
tions for land application. Also it is important
to consult with your local, state, or regional
agriculture extension center on appropriate .
nutrient concentrations for plant growth. If the
risk evaluation indicates that a waste is appro-
priate for land application, but subsequent soil
or plant tissue testing finds excessive levels of
metals, you can consider pretreating the waste
with a physical or chemical process, such as
chemical precipitation to remove some metals
before application.
F. Carbon-to-Nitrogen Ratio
The carbon-to-nitrogen ratio refers to the
relative quantities of these two elements in "a
waste or soil. Carbon is associated with
organic matter, and the carbon-to-nitrogen
ratio reflects the, level of inorganic nitrogen
available. Plants cannot use organic nitrogen,
but they can absorb inorganic nitrogen such
as ammonium. For many wastes, the carbon-
to-nitrogen ratio is computed as the dry
weight content of organic carbon 'divided by
the total nitrogen content of waste. |
Some wastes rich in organic materials (car-
bon) can actually induce nitrogen deficien-
cies. This occurs when wastes provide carbon
in quantities that microbes cannot process
without depleting available nitrogen. Soil.
microbes use carbon to build cells and nitro-
gen to synthesize proteins. Any excess organ-
ic nitrogen is then converted to inorganic
nitrogen, which plants can use. The carbon-
to-nitrogen ratio tells whether excess .organic
nitrogen will be available for this conversion.
When the carbon-to-nitrogen ratio is less
than 20 to 1—indicating a high nitrogen con-
tent—organic nitrogen is mineralized, or con-
Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. To
order, call NRAES at 607 255-7654 and request publication number NRAES-100.
7C-8
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Protecting Ground Water—Designing A Land Application Program
verted from organic nitrogen to inorganic
ammonium, and becomes available for plant
growth. For maximal plant growth, the litera-
ture recommends maintaining a ratio below
20 to 1. When the carbon-to-nitrogen ratio is
in the range of 20 to 1 to 30 to 1—a low
nitrogen content—^soil micro-organisms use
much of the organic nitrogen to synthesize
proteins, leaving only small excess amounts
to be mineralized. This phenomenon, known
as immobilization, leaves little inorganic
nitrogen available for plant uptake. When the
carbon-to-nitrogen ratio is greater than 30 to
1, immobilization is the dominant process,
causing stunted plant growth. The period of
immobilization, also known as nitrogen or
nitrate depression, will vary in length
depending on the decay rate of the organic
matter in the waste. As a result, plant growth
within that range might not be stunted, but is
not likely to be maximized.
How can I manage changing
carbon-to-nitrogen ratios?
The cycle of nitrogen conversions within
the soil is a complex, continually changing
process (see Figure 2). As a result, if applying
waste based only on assumed nitrogen miner-
alization rates, it is often difficult to ensure
that the soil contains sufficient inorganic
nitrogen for plants at appropriate times. If
you are concerned about reductions in crop
yield, you should monitor the soil's carbon-
to-nitrogen ratio and, when it exceeds 20 to
1, reduce organic waste application and/or
supplement the naturally mineralized nitro-
gen with an inorganic nitrogen fertilizer, such
as ammonium nitrate. Methods to measure
soil carbon include EPA Method 9060 in Test
Methods for Evaluating Solid Waste,
Physical/Chemical Methods—SW-846. Nitrogen
content can be measured with simple labora-
tory titrations.
G. Soluble Salts
The term soluble salts refers to the inorganic
soil constituents (ions) that are dissolved in the
soil water. Major soluble salt ions include calci-
um (Ca2*), magnesium (Mg2*), sodium (Na*),
potassium (K*), chloride (CIO, sulfate (SO42'),
bicarbonate (HCO3'X and nitrate (NCy). Total
dissolved solids (TDS) refers to the total
amount of all minerals, organic matter, and
nutrients that are dissolved in water. The solu-
ble salt content of a material can be determined
by analyzing the concentration of the individ-
ual constituent ions and summing them, but
this is a lengthy procedure. TDS of soil or
waste can reasonably be estimated by measur-
ing the electrical conductivity (EC) of a mixture
of the material and water. EC can be measured
directly on liquid samples. TDS is found by
multiplying the electrical conductivity reading
in millimhos/cm (mmhos/cm) by 700 to give
TDS in parts per million (ppm) or mg/1.
Soluble salts are important for several rea-
sons. First, saline soil, or soil with excessive
salt concentrations, can reduce plant growth
and seed germination. As salt concentration
in soil increases, osmotic pressure effects
make it increasingly difficult for plant roots to
extract water from the soil. Through a certain
range, this will result in reduced crop yield,
up to a maximum beyond which crops will
be unable to grow. The range and maximum
for a few representative crops are shown in
Table 2. For this reason, the salt content of
the waste, rather than its nitrogen content,
can be the primary determinant of its agricul-
tural suitability for land application, especial-
ly on irrigated soils in arid regions.
The second reason soluble salts are impor-
tant is that sodic soil, or soil with excessive
levels of sodium ions (NaO relative to diva-
lent ions (Ca2+, Mg2>), can alter soil structure
and reduce soil permeability. The sodium
absorption rate (SAR) of a waste is an indica-
tor of its sodicity. To calculate the SAR of a
7C-9
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Protecting Ground Water—Designing A Land Application Program
Table 2:
Salinity Tolerance of Selected Crops
So;il Salinity (mmhos/cm)" that /will result in:
0% yield
reduction11
50% yield
reduction11
100°|> yield
reduction1"
Alfalfa
Bermuda grass
Clover
Perennial rye
Tall fescue
2.0
6.9
1.5
5.6
3.9
•8.8
• 14.7
10.3
12.1
13.3
16
23
19! -
19 ;
32 ;
Source: Borrelli, J. and D. Brosz. 1986. Effects of Soil Salinity on Crop Yields.
' A rule of thumb from the irrigation industry.holds that soil salinity will be 1 Vi times the salinity of applied
irrigation water. The effect that waste salinity will have on soil salinity, however, is not as easily predicted
and depends on the waste's water content and other properties and on the application rate.
* Reductions are stated as a percentage of maximum expected yield.
waste or soil, determine the Na*, Ca2*, and
Mg2* concentrations in milliequivalents per
liter3 for use in the following equation:9
SAR =
Na*
V
Mg2*;)
Soils characterized by both high salts
(excessive TDS as indicated by EC) and
excessive sodium ions (excessive Na* as indi-
cated by SAR) are called saline-sodic soils,
and can be expected to have the negative
characteristics of both saline soils and sodic
soils described above. Table 3 displays EC
and SAR levels indicative of saline, sodic, and
saline-sodic soils.
The third reason soluble salts are impor-
tant is that specific ions can induce plant tox-
icities or contaminate ground water. Sodium
and chloride ions, for example, can become.
phytotoxic at high concentrations. To: assess
sodic- or toxic-inducing characteristics, you
should conduct an analysis of specific ions in
addition to measuring EC. :
What can I do if a waste is either
saline or sodic?
Saline waste. If a waste is saline, careful
attention to soil texture, plant selection, and
application rate and timing can help. Coarse
soils often have a lower clay content and are
less subject to sodium-induced soil structure
7C-10
The term milliequivalents per liter (meq/1) expresses the concentration of a dissolved substance in
terms of its combining weight. Milliequivalents are calculated for elemental ions such as Na*, Ca2*, and
Mg2* by multiplying the concentration in mg/1 by the valence number (1 for Na*, 2 for Ca2+ or Mg2*)
and dividing by the atomic weight (22.99 for Na*, 40.08 for Ca2*, or 24.31 for Mg2*).
If the proper equipment to measure these concentrations is not available, consider sending soil and
waste samples to a soil testing laboratory, such as that of the local extension service (visit for contact information) or nearby university. Such a laboratory will be
able to perform the necessary tests and calculate the SAR.
-------
Protecting Ground Water—Designing-A Land Application Program
- ' - Tables
EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils
; • Soil Characterization : ' -' /-; ' ; • ; -
----•;• Normal .;•-''--. Saline ,.,- : '•.'-':<• Sodic -~
= ; i '' ' -_._•-- " .- _•"_-, - ; / ; - • v . - •;"-"."
EC" < 4 and
SARb< 13
EC>4
SAR>13
Saline-Sodic
EC> 4 and
SAR> 13 .
Source: Fipps, G. Managing Irrigation Water Salinity In the Lower Rio Grande Valley.
aln units of mmhos/cm "dimensionless
problems. While coarse soils help minimize
soil structural problems associated with salin-
ity, they also have higher infiltration,and per-
meability rates, which allow for more rapid
percolation or flushing of the root zone. This
can increase the risk of waste constituents
being transported to ground water.
Since plants vary in their tolerance to
saline environments, plant selection also is
important. Some plant species, such as rye
grass, canary grass, and bromegrass, are only
moderately tolerant and exhibit decreased
growth and yields as salinity increases. Other
plants, such as barley and bermuda grass, are
more saline-tolerant species.
You should avoid applying high salt con-
tent waste as much as possible. For saline
wastes, a lower application rate, and thor-
ough tilling or plowing can help dilute the
overall salt content of the waste by mixing it
with a greater soil volume. To avoid the
inhibited germination associated with saline
soils, it also can help to time applications of
high-salt wastes well in advance of seedings.
Sodic waste. SAR alone will not tell how
sodium in.a waste will affect soil permeability;
it is important to investigate the EC of a waste
as well. Even if a waste has a high SAR, plants
might be able to tolerate this level if the waste
also has an elevated EC. As with saline waste,
for sodic waste select a coarser-textured soil to
help address sodium concerns. Adding gyp-
sum (CaSO4) to irrigation water can also help
to reduce the SAR, by increasing soil calcium
levels. Although this might help address sodi-
um-induced soil structure problems, if choos-
ing to add constituents to alter the SAR, the
EC should also be monitored to ensure salini-
ty levels are not increased too much.
H. Calcium Carbonate
Equivalent
Calcium carbonate equivalent (CCE) is
used to measure a waste's ability to neutralize
soil acidity—its buffering capacity—as com-
pared with pure calcium carbonate. Buffering
capacity refers to how much the pH changes
when a strong acid or base is added to a solu-
tion. A highly buffered solution will show
only a slight change in pH when strong acids
or bases are added. Conversely, if a solution
has a low buffering capacity, its pH will
change rapidly when a base or acid is added
to it. If a waste has a 50 percent CCE, it
would need to be applied at twice the rate of
pure calcium carbonate to achieve the same
buffering effect.
I. Pathogens
Potential disease-causing microorganisms
or pathogens, such as bacteria, viruses, proto-
zoa, and the eggs of parasitic worms, might
be present in certain wastes. Standardized
7C-11
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Protecting Ground Water—Designing A Land Application Program
testing procedures are available to help deter-
mine whether a waste contains pathogens.
You should consider using such tests espe-
cially if your process knowledge indicates
that a waste might contain pathogens. Fecal
coliform bacteria can be quantified, for exam-
ple, by using a membrane filtering technique,
which involves passing liquid waste through
a filter, incubating the filtrate (which contains
: the bacteria) on a culture medium for 24
: hours, and then counting the number of bac-
terial colonies formed.
: How can I reduce pathogenic
risks?
Methods to reduce pathogenic risk include
disinfecting or stabilizing a waste prior to
land application. Examples of treatment
methods recognized for sewage sludge
stabilization are included in the sidebar.
Pathogens present a public health hazard if
they are transferred to food or feed crops,
contained in runoff to surface waters, or
transported away from a land application site
by vectors. If pathogen-carrying vectors are a
concern at a site, it is important to establish
measures to control them. For examples of
• methods to control vectors, refer to Chapter
8-Operating the Waste Management System.
Additional information on pathogen reduc-
tion and methods to control vectors can be
obtained from 40 CFR 503.15 and 40 CFR
503.32 (EPA's Sewage Sludge Rule.) A dis-
cussion of these alternatives is available in
EPA's guidance document Land Application of
Sewage Sludge: A Guide for Land Appliers on
the Requirements of the Federal Standards for
the Use or Disposal of Sewage Sludge, 40 CFR
. Part 503 (U.S. EPA, 1994a).
The services of a qualified engineer might
be necessary to design an appropriate process
for reducing pathogens in a waste. You
: should consult with the state to determine
whether there are any state-specific require-
What are methods for stabilizing
waste prior to land application?^
The following methods, recommended
for stabilizing sewage sludge, can also be .
useful for reducing pathogens in waste:
t
• Aerobic digestion
• .Air drying
• Anaerobic digestion
• Composting " ' ' ,
• Lime stabilization'
More detailed information on each of
these and other methods can be found
in EPA's Control of Pathogens and Vector
Attraction in Sewage Sludge (U.S. EPA,
1992). '. - , i- ,
ments for pathogen reductions for specific
waste types.
III. Measuring Soil
Properties
Physical, biological, and chemical charac-
teristics of the soil are key factors in deter-
mining its capacity for waste attenuation. If
the soil is overloaded, rapid oxygen deple-
tion, extended anaerobic conditions, and the
accumulation of odorous and phytotoxic
end-products can impair soil productivity
and negatively impact adjacent properties.
With proper design and operation, waste can
be successfully applied to almost any soil;
however, sites with highly permeable s.oil
(e.g., sand), highly impermeable soil (e.g.,
clay), poorly drained soils, or steep slopes
can present special design issues. Therefore,
it is advisable to give such sites lower priority
during the site selection process. >
7C-12
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Protecting Ground Water—Designing A Land Application Program
How can I evaluate the soil at a
site?
To help evaluate the soil properties of a
site, you should consult the U.S. Department
of Agriculture (USDA) soil survey for the
prospective area. These surveys provide infor-
mation on properties such as soil type and
permeability. USDA has prepared soil surveys
for most counties in each state. To obtain a
copy of the survey for an area, contact the
Natural Resource Conservation Service offices,
the county conservation district, the state agri-
cultural cooperative, extension service, or local
health authorities/planning agency. These soils
surveys will help during site selection; howev-
er, conditions they describe can differ from
the actual soil conditions.
Several guidance documents on soil sur-
veys are also available from USDA. These
documents include the National Soil Survey
Handbook and the guide Soil Taxonomy: A
Basic System of Soil Classification for Making
and Interpreting Soil Surveys. The National Soil
Survey Handbook provides an abundance of
information including help on interpreting
soil surveys, a primer on soil properties and
soil quality, and guides for predicting the per-
meability of your soil. Both of these docu-
ments are available over the Internet and can
be obtained from .
For more site-specific data on actual soil
conditions, you can sample and characterize
the soil. It might be desirable to have a quali-
fied soil scientist perform this characteriza-
tion, which often includes soil texture,
percentage of organic matter, depth to water
table, soil pH, and cation exchange capacity.
At a minimum, you should characterize sam-
ples from an upper soil layer, 0 to 6 inches,
and a deeper soil layer, 18 to 30 inches, and
follow established soil sampling procedures to
obtain meaningful results. If a detailed charac-
terization is desired, or if it is suspected soil
types vary considerably, further subdivision of
soil horizons or collection of samples over a
greater variety of depths might be appropriate.
For more information about how to obtain
representative soil samples and to submit
them for analysis, you can consult EPA's
Laboratory Methods for Soil and Foliar Analysis
in Long-^Term Environmental Monitoring
Programs (U.S. EPA, 1995d), or state guides,
such as Nebraska's Guidelines for Soil Sampling,
G91-1000.
Why are chemical and biological
properties of soil important?
Chemical and biological properties of the
soil, like those of the waste, influence the
attenuation of waste constituents. These
properties include pH, percentage of organic
matter, and cation exchange capacity. Affected
attenuation processes in the soil include
absorption, adsorption, microbial degrada-
tion, biological uptake, and chemical precipi-
tation. For example, adsorption—the process
by which molecules adhere to the surface of
other particles, such as clay—increases as the
cation exchange capacity and pH of the soil
increase. Cation exchange capacity, in turn, is
dependent on soil composition, increasing as
the clay content of the soil increases.
Adsorption through cation exchange is an
important means of immobilizing metals in
the soil. Organic chemicals,' on the other
hand, are negatively charged and can be
adsorbed through anion exchange, or the
exchange of negative ions. A soil's capacity for
anion exchange increases as its pH decreases.
Why are physical properties of
soil important?
Physical properties of the soil such as tex-
ture, structure, and pore-size distribution affect
infiltration rates and the ability of soil to filter
or entrap waste constituents. Infiltration and
permeability rates decrease as clay content
7C-13
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Protecting Ground \Vater—Designing A Land Application Program
increases. Sites with soils with permeabilities
that are too high or too low have lower land
application potential. Soils with high perme-
ability can allow wastes to move through with-
out adequate attenuation. Soils with low
permeability can cause pooling or excessive
surface runoff during intense rainstorms.
Excessive runoff conditions can be compensat-
ed for somewhat by minimizing surface slope
during site selection. Soils with low perme-
ability are also prone to hydraulic overloading.
The amount of liquid that can be assimi-
lated by a soil system is referred to as its
hydraulic loading capacity. In addition to a
soils permeability, hydraulic loading capacity
is dependent on other factors such as cli-
mate, vegetation, site characteristics, and
other site-specific soil properties such as soil
type, depth to seasonally high water table,
slope and credibility, water intake rate, and
underlying geology and hydrogeology.
Exceeding the hydraulic loading capacity of a
site, can lead to rapid leaching of waste con-
stituents into ground water, reduction in bio-
logical activity, sustained anaerobic
conditions, soil erosion, and possible conta-
mination of surface waters. It can also result
in excessive evaporation, which can cause
excessive odor and unwanted airborne emis-
sions. In order to avoid hydraulic overload-
ing at a site, application of liquid or
semi-liquid waste or wastewater should be
managed so uncontrolled runoff or prolonged
saturation of the soil does not occur.
An important indicator of soil properties is
its topography, which affects the potential for
soil erosion and contaminated surface-water
runoff. Soils on ridge tops and steep slopes
are typically well drained, well aerated, and
shallow. Steep slopes, however, increase the
likelihood of surface runoff of waste and of
soil erosion into surface waters. State guide-
lines, therefore, often specify the maximum
slopes allowable for land application sites for
various waste characteristics, application
techniques, and application rates. The| agen-
cies that regulate land application in a. state
can provide specific guidance concerning
slopes. Soils on concave land and broad flat
lands, on the other hand, frequently are
poorly drained and can be waterlogged dur-
ing part of the year. Soils in relatively flat
areas can have intermediate properties with
respect to drainage and runoff and could be
more suitable for land application. :
IV. Studying the
Interaction of
Plants arid
Microbes with
Waste
The next step in the design of a land
application unit is to consider the plants and
microbes at the site and how they will inter-
act with the waste. This interaction iricludes
the uptake and degradation of waste con-
stituents, the effects of the wastes on plant
and microbial growth, and changes that can
occur in plants or crops affecting their use as
food or feed. The uptake of nutrients ;by
plants and microbes on plant roots or in soil
affects the rate of waste assimilation and .
biodegradation, usually increasing it.:
It might be necessary to conduct green-
house or field studies or other tests of-plants,
soil,' and microbes to understand and quanti-
fy these interactions. You should consult with
the state agricultural department, the, local
health department, and other appropriate
agencies if considering land application of
wastes containing designated grounds-water
constituents or other properties that are
potentially harmful to food or feed crops.
Industry groups might also be able to pro-
vide information about plants with which
they have land application experience.
7C-14
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Protecting Ground Water—Designing A Land Application Program
A. Greenhouse and Field
Studies
State agricultural extension services, depart-
ments of environmental protection, or public
universities might have previous studies about
plant uptake of nutrients, especially nitrogen,
phosphorus, and potassium, but it is impor-
tant to recognize that the results of studies
conducted under different conditions (such as
different waste type, application rate, plant
type, or climate) are only partially relevant to a
specific situation. Furthermore, most studies to
date have focused on relatively few plant
species, such as com, and only a handful of
constituents, typically metals. Greenhouse
studies or pilot-scale field studies attempt to
model site-specific conditions by growing the
intended crops in soil from the prospective
application site. These studies are useful
because individual parameters can be varied,
such as plant type and waste application rate,
to determine the effects of each factor.
Additionally, greenhouse or field studies might
be required by some state's to certify that a
waste has agricultural benefits. Generally, the
first point of contact for assistance with studies
is the state agricultural extension service. Many
state extensions can conduct these studies;
others might be able to provide guidance or
expertise but will recommend engaging a pri-
vate consultant to conduct the studies.
How do I conduct greenhouse or
field studies?
Currently, no national guidelines exist for
conducting greenhouse or field studies,'-" but
check to see if the state has 'guidance on
accepted practices. Working with a state agri-
cultural extension service or a local university
will provide the benefit of their expertise and
experience with local conditions, such as
which 'plants are suitable for local soils and
climate. If a particular industry sector has a
large presence -in a state, the state agricultural
extension service might have previous experi-
ence with that specific type of waste.
Greenhouse studies. Aside from their
smaller scale, greenhouse studies differ from
field studies primarily in that they are con-
ducted indoors under controlled conditions,
while field studies are conducted under nat-
ural environmental conditions. A greenhouse
study typically involves distributing represen-
tative soil samples from the site into several
pots to test different application rates, appli-
cation methods, and crops. Using several
duplicate pots for each rate, method, or crop
allows averaging and statistical aggregating of
results. It is also important to establish con-
trol pots, some with no waste and no plants,
others with waste but no plants (to observe
the extent to which waste assimilation effects
are due to soil and pre-existing microbes) and
still others with plants but without waste (as
a baseline for comparison with waste-amend-
ed plant growth).
To the
extent
feasible,
tempera-
ture,
mois-
ture, and
other
parame-
ters should simulate actual site conditions.
There should be a series of several duplicate
pots grown with each combination of plant
type, application rate, and other parameters.
Pots should be arranged to avoid environ-
mental conditions disproportionately affecting
one series of pots. For example, you should
avoid placing a whole series of pots in a row
closest to a light source; instead, it is better to
place one pot from each of several series in'
that row or randomize placement of pots.
The controlled greenhouse environment
allows the study of a wide range of waste-soil
10 Based on conversations with Dr. Rufus L. Chaney and Patricia Milner, U.S. Department of Agriculture.
7C-15
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Protecting Ground Water—Designing A Land Application Program"
interactions without risking the loss of plants
due to weather, animal hazards, and other
environmental influences. At the same time,
this can introduce differences from actual
conditions. Root confinement, elevated soil
temperature, and rapidly changing moisture
levels, for example, can increase the uptake
of pollutants by potted plants compared to
uptake under field conditions.11
Field studies. Field studies, on the other
hand, can test application rates and crops on
plots at the actual proposed site. As with
greenhouse studies, duplicate plots are useful
for statistical purposes, and controls are
needed. Field study data can be more useful
because it more closely reflects real-world
conditions, but it also can be more difficult
to obtain because of uncontrollable circum-
stances such as flooding or unusual pest
damage that can occur at the time of the
study. Field studies also can be subject to sit-
ing, health and safety, and permitting
requirements.
Field studies also help determine the actu-
al land area required for land application and
the quality of runoff generated. Soil and
ground-water monitoring help to confirm
that waste constituents are being taken up by
plants and not leaching into the ground
water. Results from field studies, however,
might not be duplicated on actual working
plots after multiple waste applications, due to
long-term soil changes. Crop yields also can
vary by as much as 15 to 25 percent under
field conditions, even with good fertility and
management.
Both greenhouse and field studies typically
include extensive sampling of waste, soil
before application, plants or representative
parts of plants, soil after application, growth
of plants, and, to the extent feasible, water.
You should sample soil at the surface and in
lower horizons using core sampling. Some
soil tests require mixing samples with;water
to form a paste or slurry. Plant tissue tests
often require dry-weight samples, made: by
drying cut plants at about 65°C. Water can
be collected in lysimeters (buried charnbers
made from wide perforated pipe) and
removed using hand pumps. ;
The effects of waste on organisms in the
soil can also be monitored during greenhouse
and field studies. The literature suggests, that
the effects of waste on earthworms are a good
indicator of effects on soil organisms rn gen-
eral. It might be worthwhile, therefore, to
stock greenhouse pots or field study plots
with earthworms at the beginning of a study
and monitor the waste constituent levels and
the effects on the worms during and at the
end of the study. Although these brief: studies
will not effectively model long-term exposure
to waste constituents, it is possible to [gauge
short-term and acute effects.
B. Assessing Plant and
Microbial Uptake Rates
Plants. After performing studies, you
should measure the amounts of various
nutrients, metals, and other constituents in
tissue samples from plants grown in the
greenhouses or on test plots. This tells
approximately how much of these con-
stituents the plants extracted from the soil-
waste mix. By measuring plant-extracted
quantities under these various .conditions,
you can determine a relationship between
11 If a waste contains VOCs, ensure the possibility of VOCs accumulating within the enclosed greenhouse
is addressed.
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Protecting Ground Water—Designing A Land Application Program
plant type, application rate, and nutrient
extraction. From this, you can choose the
conditions which result in the desired uptake
rate while avoiding uptake of designated
ground-water constituents at undesirable "
concentrations. Plant uptake is often mea-
sured as a ratio of the pollutant load found in
the plants to the pollutant load applied to the
land as illustrated below:
fig pollutant
g dry plant tissue
per
kg pollutant
hectare
stituents in the process of using other com-
pounds as an energy source. Aerobic microor-
ganisms require oxygen to metabolize waste
and produce carbon dioxide and water as end
products. Anaerobic microbes function with-
out oxygen but produce methane and hydro-
gen sulfide as end products. These gases can
present a safety risk as well as environmental
threats, and hydrogen sulfide is malodorous.
For these reasons, it is recommended that
you maintain conditions that favor aerobic
microbes.
For many microorganisms, these condi-
tions include a pH of 6 to 8 and temperatures
of 10°C to 30°C. In addition, microbes might
be unable to transfer oxygen from soil effi-
ciently if the moisture content is near satura-
tion, or they might be unable to obtain
sufficient water if the soil is too dry. A water
content of 25 to 85 percent of the soil's water
holding capacity is recommended in the liter-
ature. Oxygen generally is available through
diffusion from the atmosphere, but this
mechanism might provide insufficient oxygen
if there is too, little pore-space (less than 10
percent of soil volume) or if so much organic
matter is applied that oxygen is consumed
faster than it is replaced. ;
C. Effects of Waste on
Plant and Microbe
Growth
Greenhouse and field studies can tell what
effect the waste will have on plant growth pat-
terns. A typical method of quantifying plant
growth is to state it in terms of biomass pro-
duction, which is the dry weight of the cut
plants (or representative parts of the plants). If
the plants grown with waste applications
show greater mass than the control plants,12
the waste might be providing useful nutrients
or otherwise improving the soil. If the plants
grown with waste applied at a certain rate
12 Trends detected in studies assume that results have been subjected to tests of statistical validity before
finding a trend significant.
This ratio serves to place pollutant uptake
in the context of the original amount of pol-
lutant applied.
In choosing plants for a land application
unit, you should also consider growing seasons
in relation to periods of waste application rate.
Specific waste application rates associated with
corresponding uptakes of nutrients by plants,
as indicated in greenhouse or field studies, are
applicable only during the growing phases cov-
ered by the study At other times, .waste appli- .
cation might be infeasible because plants are
not present to help assimilate waste, or because
plants are too large to permit passage of appli-
cation equipment without sustaining damage.
Microbes. Certain microbes can biode-
grade organic chemicals and other waste con-
stituents. Some accomplish this by directly
using the constituents as a source of carbon
and energy, while others co-metabolize con-
7C-17
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Protecting Ground Water—Designing A Land Application Program
weigh less than the controls, some con-
stituent(s) in the waste might be excessive at
the studied application rate. Comparing the
results from several different application rates
can help find the rate that maximizes growth
and avoids detrimental and phytotoxic effects.
Analyzing soil and water after plant growth
allows for a comparison between the planted
pots or plots against the control to discern the
differences due to plant action. If water sam-
ples show excessive nutrient (especially nitro-
gen) levels at a certain application rate, this
might indicate that the plants were unable to
use all the nutrients in the waste applied at
that rate, suggesting that the application was
excessive. If soil and water tests show that
constituents are consumed, and if other possi-
ble causes can be ruled out, microbes might
be responsible. Further investigation of
microbial action might involve sampling of
microbes in soil, counting their population,
and direct measurement of waste constituents
and degradation byproducts.
D. Grazing and Harvesting
Restrictions
If a waste might contain pathogens'or des-
ignated ground-water constituents, and the
established vegetative cover on the land
application site is intended for animal con-
sumption, it is important to take precautions
to minimize exposure of animals to these
contaminants. This is important because ani-
mals can transport pathogens and ground-
water constituents from one site to another,
and can be a point of entry for waste con-
stituents and pathogens into the food chain.
If harvesting crops from a unit for use as
animal fodder, you should test plants for the
presence of undesirable levels of the desig-
nated ground-water constituents before feed-
ing. Grazing animals directly on a unit is
discouraged by some states.13 If considering
direct grazing, you should consult with the
state to see if there are any restrictions on
this practice. Growing crops for human con-
sumption on soil amended with waste calls
for even greater caution. In some states, this
practice is prohibited or regulated, ancl in
states where it is allowed, finding food
processors or distributors willing to purchase
such crops can be difficult. :
When testing crops before feeding:them
to animals, local agricultural extension ser-
vices might be able to help determine what
levels are appropriate for animal consump-
tion. If plant tissue samples or findings of a
fate and transport model indicate waste con-
stituent levels inappropriate for animal con-
sumption, it is important that you not use
harvested plants as fodder or allow grazing
on the site. Additionally, plants with high
constituent levels will probably be inappro-
priate for other agricultural use, and thus
would likely necessitate disposal of such
crops as a waste, after harvest. , ;
V. Considering
Direct Exposure,
Ecosystem
Impacts, &
Bioaccumuiatlon
of Waste
You should evaluate the impacts that your
land application unit will have on direct
exposure and ecological pathways as well as
the potential for bioaccumulation of land-
applied waste. During the land application
units active life, direct human exposure to
waste or waste-amended soil is primarily a
risk to personnel involved in the operation.
You should follow OSHA standards and
ensure that personnel are properly trained
and use proper protective clothing and equip-
" Grazing can also be unwise due to potential effects on soil physical structure. The weight of heavy ani-
mals can compact soil, decreasing pore space, which can reduce the soil's waste attenuation capacity.
7C-18
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Protecting Ground Water—Designing A Land Application Program
men: when working onsite. You should limit
direct exposure to others through steps such
as access control and vehicle washing to pre-
vent tracking waste and waste amended soil
off site.
Access control will also limit exposure of
some animals. If crops will be used for animal
fodder or grazing, you should test harvested
fodder for the designated ground-water con-
stituents before use and restrict grazing times.
After a site is closed, there might be long-term
access risks to future land uses and the gener-
al public. To minimize these risks, long-term
access controls or deed restrictions might be
appropriate. Consult Chapter 11—Performing
Closure and Post-Closure Care for further
information.
Direct exposure of native animals is often
impossible to control and might be an entry
point for the ground-water constituents into
the food chain. Worms, for example, might
be present in the soil and take in these con-
stituents. Birds or other animals could then
consume the worms, bioaccumulate, or be
transported off site. Furthermore, animals can
ingest plants grown on waste-amended soil.
Therefore, you should also consider pathways
such as these in evaluating your plans for
land application.
VI. Accounting for
Climate
Local climate considerations should also
enter into your land application planning
process. For example, wastes that are high in
soluble salts are less appropriate and can have
deleterious effects in arid climates due to the
osmotic pressure from the salts inhibiting root
uptake of water. On the other hand, the down-
ward movement of water in the soil is minimal
in arid climates, making the migration of waste
constituents to ground water less likely.
Climate also determines which plants can
grow in a region and the length of the grow-
ing season. If the local climate cannot sup-
port the plants that might be most helpful in
assimilating the particular constituents in a
given waste, the use of land application might
be limited to other crops at a lower applica-
tion rate. If the climate dictates that the part
of the growing cycle during which land appli-
cation is appropriate is short, a larger area for
land application might be necessary.
There are also operating considerations
associated with climate. Since waste should
not be applied to frozen or very wet soil, the
application times can be limited in cold or
rainy climates. In climates where the ground
can freeze, winter application poses particular
problems even when the ground is not frozen,
because if the ground freezes soon after appli-
cation, the waste that remained near the soil
surface can run off into surface waters during
subsequent thaw periods. Waste nutrients are
also more likely to leach through the soil and
into the ground water following spring thaw,
prior to crop growth and nutrient uptake.
These problems can be partially solved by
providing sufficient waste storage capacity for
periods of freezing or rainy weather.
VII. Calculating An
Agronomic
Application Rate
The purpose of a land application unit
(i.e., waste disposal versus beneficial use)
helps determine the waste application rate
best suited for that unit. When agricultural
benefits are to be maximized, the application
rate is governed by the agronomic rate. The
objective for determining an agronomic appli-
cation rate is to match, as closely as possible,
the amount of available nutrients in the waste
with the amount required by the crop. One
7C-19
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Protecting Ground Water—Designing A Land Application Program
example of an equation for calculating agro-
nomic application rates is:
Agronomic application rate = (Crop nutri-
ent uptake x Crop yield)-Nutrient credits
Where:
Crop nutrient uptake = Amount of nutri-
ents absorbed by a particular crop. These
requirements are readily available from
your state and local Cooperative Extension
Offices
Crop yield = Amount of plant available for
harvest. Methods for calculating expected
yields include past crop yields for that
unit, county yield records, soil productivi-
ty tables, or local research.
Nutrient credits = Nitrogen residual from
past waste applications, irrigation water
nitrate nitrogen, nutrients from commer-
cial fertilizer, and other nitrogen credits
from atmospheric deposition from dust
and ammonia in rainwater.
In addition, many states and universities
have developed their own worksheets or cal-
culations for developing an agronomic appli-
cation rate. You should check with your state
agency to see if you are subject to an existing
regulation. In setting a preliminary applica-
tion rate the crop's nitrogen requirements :
often serve as a ceiling, but in some cases,
phosphorus, potassium, or salt content, rather
than nitrogen, will be the limiting factor.
How do I determine the agro-
nomic rate? • ',
Computer models can help determine site-
specific agronomic rates. Modeling nitrogen
levels in waste and soil-plant systems can help
provide information about physical and
hydrologic conditions and about climatic
influences on nitrogen transformations.
Models recommended for use with sewage
sludge include Nitrogen Leaching and
Economic Analysis Package (NLEAP);
DECOMPOSITION; Chemicals, Run-Off, and
Erosion from Agricultural Management
Systems (CREAMS); and Ground-Water
Loading Effects of Agricultural Management
Systems (GLEAMS).14 NLEAP is a moderately
complex, field scale model that assesses the
potential for nitrate leaching under agricultur-
al fields. NLEAP can be used to compare
nitrate leaching potential under different soils
and climates, different cropping systems, and
different management scenarios. The comput-
er model DECOMPOSITION is specifically
designed to help predict sewage sludge nitro-
gen transformations based on sludge charac-
teristics, as well as climate and soil properties
(organic matter content, mean soil tempera-
ture, and water potential). Finally, the
CREAMS and GLEAMS models, developed by
the USDA, are other potentially useful models
to assist with site-specific management of land
application operations. Additional computer
models include Cornell Nutrient Management
Planning System (NMPS), Fertrec Plus v 2.1,
and Michigan State University Nutrient
7C-20
" All of these models are referenced in EPA's Process Design Manual: Land Application of Sewage Sludge and
Domestic Septage (U.S. EPA, 1995b). According to that source, the NLEAP software, developed by
Shaffer et al., is included in the purchase of Managing Nitrogen for Ground-water Quality and Farm
Profitability by Follet, et al., which also serves as reference for information on parameters required for
nitrogen calculations. Four regional soil and climatic databases (Upper Midwest, Southern, j
Northeastern, and Western) also are available on disk for use with NLEAP. These materials can be
obtained from: Soil Science Society of America Attn: Book Order Department, 677 S. Segoe Road,
Madison, WI 53711, 608/273-2021; Book $36.00; Regional Databases $10.00 each. Currentiupdates of
the NLEAP program can be obtained by sending original diskettes to: Mary Brodahl, USDA-ARS-GPSR,
Box E, Fort Collins, CO 80522. Additional information on the DECOMPOSITION model, developed
by Gilmour and Clark, can be obtained from: Mark D. Clark, Predictive Modeling, P.O. Box 610,
Fayetteville, AR 72702. The CREAMS and GLEAMS models were developed by USDA. ;
-------
Protecting Ground Water—Designing A Land Application Program
Management vl.l.15 If assistance is required in
determining an appropriate agronomic rate for
a waste, you should contact the regional, state,
or county agricultural cooperative extensions,
or a similar organization.
VIII. Monitoring
Monitoring ground water can be helpful to
verify whether waste constituents have migrat-
ed to ground water. Some state, tribal, or
other regulatory authorities require ground-
water monitoring at certain types of land
application units; you should consult with the
appropriate regulatory agency to determine
whether such a requirement applies to the
unit. Even if the unit is not required to moni-
tor ground water, instituting a ground-water
monitoring program is recommended for
long-term, multiple application units where
wastes contain the designated ground-water
constituents. Such units are more likely to
pose a threat to ground water than are single-
application units or units receiving waste
without these constituents.
In most cases, lysimeters should be suffi-
cient to monitor ground water. A lysimeter is
a contained unit of soil, often a box or cylin-
der in the ground which is filled with soil,
open on the top, and closed at the bottom, so
that the water that runs through it can be col-
lected. It is usually more simple and econom-
ical to construct and operate than a
monitoring well. You can consult with a qual-
ified professional to develop an appropriate
ground-water monitoring program for your
land application unit.
If ground-water results indicate unaccept-
able constituent levels, you should suspend
land application until the cause is identified.
You should then correct the situation that led
to the high readings. If a long-term change in
the industrial process, rather than a one-time
incident, caused the elevated levels, you
should reevaluate your use of land applica-
tion. Adjusting the application rate, adding
pretreatment, or switching to another means
of waste management might be necessary.
After reevaluation, you should examine
whether corrective action might be necessary
to remediate the contaminated ground water.
You should pay particular attention to ensure
that applications are not exceeding the soil's
assimilative capacity.
You should also consider testing soil sam-
ples periodically during the active life of a
land application unit. For this testing to be
meaningful, it is important that you first
determine baseline conditions by sampling
the soil before waste application begins. This
might already have been done in preparation
for greenhouse/field studies or for site charac-
terization. Later, when applying waste to the
unit, you should collect and analyze samples
at regular intervals (such as annually or after
a certain number of applications). Consider
analyzing samples for macronutrients,
micronutrients, and any of the designated
ground-water, constituents reasonably expect-
ed to be present in the waste. The location
and number of sampling points, frequency of
sampling, and constituents to be analyzed
will depend on site-specific soil, water, plant,
and waste characteristics. Local agricultural
extension services, which have experience
with monitoring, especially when coupled
with ground-water monitoring, can detect
contamination problems. Early detection
allows time to change processes to remedy
the problems, and to conduct corrective
action if necessary before contamination
becomes widespread.
Testing soils after the active life of a unit
ends might also be appropriate, especially if
the waste is likely to have left residues in the
soil. The duration of monitoring after closure,
like the location and frequency of monitoring
during active life, is site-specific and depends
on similar factors. For further information
15 These models are referenced in the Northeast Regional Agricultural Engineering Cooperative
Extension's Nutrient Management Software: Proceedings from the Nutrient Management Software
Workshop from December 11, 1996.
7C-21
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Protecting Ground Water—Designing A Land Application Program
about testing soil after the active life of a unit
ends, refer to Chapte 11—Performing
Closure and Post-Closure Care.
IX. Odor Controls
Odors are sometimes a common problem
at land application facilities and an odor
management plan can allow facility managers
to respond quickly and effectively to deal
with odor complaints. A plan should involve
working to prevent odors from occurring,
working with neighbors to resolve odor com-
plaints, and making changes if odors become
an unacceptable condition. The plan should
also identify the chemical odor constituents,
determine the best method for monitoring
odor, and develop acceptable odor thresh-
olds. These odor management plans can be
stand-alone plans or part of your company's
environmental management system.
To effectively deal with odor complaints, it
is important to consider creating an odor
detection and response team to identify the
source of, and quickly respond to, potential
nuisance odor conditions. Document the '..
problem as well as how it was or was .not
resolved, and notify facility managers as soon.
as possible. Odor complaints should be doc-
umented immediately in terms of the odor's
location, characteristics, the time and date,
existing meteorological conditions, suspected
specific source, information that indicates rel-
ative strength compared to other events, and
when during the day the odors are noticed.
Measuring odors can be accomplished in
two manners: olfactometry and analytical.
The olfactometry method uses trained indi-
viduals who determine the strength of an
odor. Both of these methods have advantages
and disadvantages. Some of the advantages of
the olfactometry method are that it is accu-
rately correlated with human response, it is
fast at providing a general chemical classifica-
tion, and it is usually cost effective as'a field
screening method. Disadvantages include the
requirement of highly trained individuals,
and it does not address the chemistry of the
odor problem. Analytical methods use gas
chromatographs and mass spectrophdtome-
ters to analyze vapor concentrations captured
from a sample. Some of the advantages of the
analytical method are that it allo |