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<title>Guide for Industrial Waste Management:  Building Partnerships, Protecting Ground Water, Surface Water</title>
<type>single page tiff</type>
<keyword>waste water unit ground soil liner management monitoring site surface leachate closure protecting layer epa cover quality materials clay application</keyword>

             United States
             Environmental Protection
            Solid Waste and
            Emergency Response
May 1999
Guide for Industrial Waste

  Ground Water
  Surface Water
GA>Printed on paper that contains at least 30 percent post



Industrial Waste Management
       U.S. Environmental Protection Agency
           Office of Solid Waste
          401 M Street SW (5305W)
           Washington, DC 20460


                  All aspects of this guidance are in draft form, subject to comment, and not intended to be
               used in current waste management decision-making.  The draft guidance and modeling tools
               have been developed only to address issues within the scope of the guidance.  The guidance is
               not a guideline or regulation under the Resource Conservation and Recovery Act, nor can this
               draft guidance be relied upon to create any rights ^enforceable by any party in litigation with
               the United States. EPA retains the right to modify the final guidance from time to time.


  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development of this draft guidance document.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, Exxon Company USA
Robert Giraud, DuPont Company
Jonathan Greenberg, Browning-Ferris Industries
John Harney, Citizens Round Table/PURE
Richard Jar man, National Food Processors Association
James Meiers, Indianapolis Power and Light Company
Andrew Miles, The Dexter Corporation
Scott Murto, General Motors and American Foundry Society
James Roewer, Edison Electric Institute
Edward  Repa, Environmental Industry Association
Tim Saylor, International Paper
Amy Schaffer, American Forest & Paper Association
Ed Skernolis, WMX Technologies, Inc.
Michael Wach, Western Environmental Law Center
David Wells, University of South Alabama Medical Center
Pat Gwin, Cherokee Nation of Oklahoma

Past Industrial Waste Focus Group Members
Doris Cellarius, Sierra Club
Brian Forrestal, Laidlaw Waste Systems
Michael Gregory, Arizona Toxics Information and Sierra Club
Gary Robbins, Exxon Company
Kevin Sail, National Paint & Coatings Association
Bruce Steiner, American Iron & Steel
Lisa Williams, Aluminum Association


                                    Acknowledgements  (cont.)
                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
                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, Office of Solid  Waste, U.S. EPA
                Richard Kinch, Office of Solid Waste, U.S. EPA
                Paul Cassidy, Office of Solid Waste, U.S. EPA
                John Sager, Office of Solid Waste, U.S. EPA
                Pat Cohn, Office of Solid Waste, U.S. EPA
                Dwight Hlustick, Office of Solid Waste, U.S. EPA
                Ginny Cohen-Bradley, Office of Solid Waste, U.S. ;EPA
                Charlotte Bertrand, Office of Solid Waste, U.S. EPA
                Mark Schuknecht, Office of Solid Waste, 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

                   This guidance document, CD-ROM, and the ground-water and air modeling tools were
                developed with  assistance from Eastern Research Group (Birute Vanatta and Marty Marchaterre,
                Project Officers), Science Applications International Corporation (Chris Long and Bob Stewart,
                Project Officers), HydroGeologic, Inc. (Sam Figuli, Project Officer), and Research Triangle
                Institute (Anne Cook Lutes , Project Officer and Terrence K. Pierson, Program Director).


  Parti. Getting Started
        Chapter 1.  Building Partnerships
        Chapter 2.  Characterizing Waste
        Chapter 3.  Integrating Pollution
        Chapter 4.  Considering the Site

  Part II. Protecting Air Quality
        Chapter 5.  Protecting Air

  Part III. Protecting Surface Water
        Chapter 6.  Protecting Surface Water

  Part IV. Protecting Ground Water
        Chapter 7A. Assessing Risk
        Chapter 7B. Designing and Installing Liners: Technical Considerations for Surface
                   Impoundments, Landfills, and Waste Piles
        Chapter 7C.Designing a Land Application Program

  Part V. Ensuring Long-Term Protection
        Chapter 8.  Operating the Waste Management System
        Chapter 9.  Monitoring Performance
        Chapter 10. Taking Corrective Action
        Chapter 11. Performing Closure and Post-Closure Care




EPA's Guide  for  Industrial  Waste Management


      This voluntary guide is designed to assist facility managers, state
      and tribal environmental managers, and the public to evaluate
      and choose protective practices for managing industrial waste in
      new landfills, waste piles, surface impoundments, and land appli-
      cation units. This guide identifies the components of a sound
      waste management system and why each is important. It also
      includes ground-water and air models, as well as other tools to
      help tailor waste management practices to a particular facility.

      This guidance reflects four  underlying principles:
      •  Protect human health and the environment. This is the focal point. The guidance is
         multi-media, emphasizing surface water, ground water, and air protection, with a
         comprehensive framework of technologies and practices that make up a sound waste
         management system.
      •  Tailor management practices to risks. There is enormous diversity in the nature of
         industrial wastes and the environmental settings where they are managed. The guid-
         ance provides conservative national management recommendations and user-friendly
         modeling tools to make location-specific adjustments It also identifies complex ana-
         lytic tools to conduct comprehensive site-specific analyses.
      •  Affirm 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. It is important to note that individual states or
         tribes may have more stringent or extensive regulatory requirements based on local
         or regional conditions or policy considerations. This guide complements, but does
         not supersede those regulatory programs. It can help you make decisions on meeting
         requirements and filling  potential gaps.  Facility managers and the public, consult
         with appropriate regulatory agencies throughout the process to understand their"
         requirements and how they want you to use this guide.

      •  Foster a partnership. The public, facility managers and regulatory agencies share a
         common interest in preserving quality neighborhoods, protecting the environment
         and public health, and enhancing the economic well-being of the community. This
         guide provides a common technical framework to facilitate discussion. Stay involved
         and work together to  achieve meaningful environmental results.


                   I.      Setting  the  context
                      About 7.6 billion tons of industrial solid waste are generated and managed on-site at indus-
                   trial facilities each year. Almost 97 percent is wastewater managed in surface impoundments;
                   the remainder is managed in landfills, waste piles, and land application units. Most of these
                   wastewaters are treated and ultimately discharged into surface waters under Clean Water Act
                   permits issued by EPA or state governments (National Pollutant Discharge Elimination System
                   or NPDES permits). These wastes come from; the broad spectrum of American industries. This
                   guidance is not designed to address municipal wastes or wastes defined as hazardous under
                   federal or state laws.
                      EPA and 12 state representatives selected  from the membership of the Association of State and
                   Territorial Solid Waste Management Officials (ASTSWMO) began development of this guidance in
                   1996 with the formation of a State/EPA Steering Committee. We set out with three goals: first to
                   define a baseline of management practices that protect human health and the environment; sec-
                   ond, to complement existing state and tribal regulatory programs; and third to produce an effec-
                   tive and user-friendly guide that all stakeholders will rely on. The Steering Committee is co-
                   chaired by one EPA and one state member. At;the same time, we had the benefit of a Focus
                   Group of industry and public interest stakeholders chartered under the Federal Advisory
                   Committee Act to consult with us throughout:development of the guidance. The Steering
                   Committee and Stakeholders' Focus Group members are listed in the front of this document.
                      The draft guide you have in hand reflects a remarkably productive consultative process.
                   Focus Group members provided extensive comment and commitment of their time through-
                   out. Their thoughtful input helped us to make this a more comprehensive and effective prod-
                   uct, although the final decisions are those of the Steering Committee. Right now, our work is
                   half completed. The Steering Committee will reconvene to consider the feedback we receive
                   during the comment period and continue to seek advice from the Stakeholders' Focus Group
                   as we develop the final guidance.
                    II.    Scope
                      This guidance is useful for a broad array of industrial process wastes, especially those that
                    are managed at the industrial facilities where they are generated. However, we did. not consider
                    certain extractive wastes, such as from minirig or oil and gas production, and recommendations
                    may not be suitable for these wastes without further tailoring. Furthermore, any facilities that
                    receive municipal solid waste are subject to municipal landfill criteria at 40 CFR Part 258 and
                    to separate state or tribal municipal landfill regulations and are  not addressed by this guidance.
                      The guidance  focuses on the design of new units. Liner design and siting concerns are clear-
                    ly directed at new units. However, other management recommendations, such as for ground-
                    water monitoring, corrective action, operating practices, and closure and post closure care, may
                    be helpful in making management decisions for currently operating units as well.


III.   Using  the guidance

There are a few key steps to follow:
    •  Understand and comply with all existing Federal, state or tribal regulations, permits
       and operating agreements that apply to a waste management unit. The guidance is
       designed to complement them, never to take their place.

    •  Thoroughly characterize constituents and concentrations in the waste. Waste characteri-
       zation is the foundation for choosing and implementing tailored, protective management
       practices. To assess potential ground-water risks, the guidance provides drinking water
       maximum contaminant levels (MCLs), when they exist, and health-based reference levels
       for 191 constituents. To assess potential air risks, the guidance provides inhalation
       health-based reference levels for 95 volatile and semi-volatile constituents.

    •  Take advantage of pollution prevention opportunities. Pollution prevention, recycling
       and, to some extent, treatment, can minimize reliance on waste disposal, reduce disposal
       costs and reduce future costs and liabilities for closure and post closure care and potential
       corrective action. Pollution prevention can also conserve raw materials.
    •  Build a partnership between all stakeholders who have an interest in waste manage-
       ment decisions. Keep stakeholders informed and involved on an ongoing  basis.
    •  Tailor management practices to the wastes and the environmental setting  of the unit.
       The guide covers all the components of a sound waste management system. It recom-
       mends best management practices and the key factors to take into account in siting,
       operation, design, monitoring, corrective action, closure and post closure  care. The
       guidance also directs you to a wide variety of useful tools and resources, and includes a
       number of these tools as appendices. In particular, the guidance recommends risk-
       based approaches to choose liner systems and waste application rates for ground-water
       protection and to evaluate the need for air controls.
   Here is an example of how the risk-based evaluation would work for choosing a liner system
design. For ground-water protection, the approach is three-tiered, relying on modeling fate and
transport of constituents through subsurface soils to ground water. Successive tiers in the analy-
sis incorporate more site-specific data to tailor protective management practices to your particu-
lar circumstances.

   Tier 1 - National Evaluation: Once you know the concentrations of constituents in the waste,
   generic "look-up tables" give you recommendations on appropriate liner design. If the waste
   going into a unit contains several constituents, choose the most protective liner design indi-
   cated for  any of the constituents.

   Tier 2 - Location Adjusted Evaluation: You can use location-specific data for up to seven of the
   most sensitive waste and site-specific variables to assess whether a particular liner design will
   be protective. The CD ROM version of the  guidance provides a ground-water model for Tier
   1 and 2 analyses.


                      Tier 3 - Comprehensive Site Assessment: This tier relies on a comprehensive analysis of specific
                      waste and site characteristics to assess whether a particular liner design will be protective.
                      The guidance identifies a number of models for this detailed analysis.
                    IV.   Next Steps
                      We have provided the draft guidance in a printed version, on a CD ROM and it is accessible
                   through the Internet at <www.epa.gov/osw>. Now, EPA and the state participants from
                   ASTSWMO welcome your comments on all aspects of this draft: the substantive recommenda-
                   tions, the risk-based modeling tools, practicality and user friendliness. The accompanying
                   Federal Register notice and some chapters of the guidance frame a number of key questions and
                   issues to help you get started. The public comment period will extend for six months from the
                   date of the Federal Register notice. Based on your comments, we will make revisions and release
                   the final guidance.
                      EPA and state representatives participating in this effort believe that the recommendations in
                   the final version of this guide can help to improve management of industrial waste at facilities
                   across the country. EPA and ASTSWMO will widely disseminate the final version of the guide
                   and explain the rationale behind the recommendations to regulators, industries and the public
                   to foster understanding and encourage stakeholders to integrate final recommendations in
                   future industrial planning throughout the country.
                   V.    Final Thoughts
                      This guidance is designed for users with different levels of knowledge and experience.
                    Because many of the recommendations here address complex and highly technical practices
                    and engineered systems, users are urged to seek out technical experts and resources to assist in
                    detailed planning, design and implementation.
                      Facility managers, regulatory agency staff, and the public all have a different role in ensuring
                    protective waste management and, therefore, this guidance can help all of you.
                       •   Facility managers: The guide can help you make the decisions necessary to ensure
                           environmentally responsible unit siting, design, and operation in partnership with state
                           and tribal regulators and the public.
                       •   State and tribal regulators: The guide provides a handy implementation reference that
                           complementsiyour program and can help you address any gaps.
                       •   The public: The guide can help you be an informed and knowledgeable partner in
                           addressing industrial waste management issues in your community.


        Part I
   Getting Started

     Chapter  1
Building Partnerships


I. Benefits of Building Partnerships    1-1

II.  Principles of Building Partnerships    1-1
  A. Develop a Partnership Involvement Plan 1-2
  B. Inform the State and Public About New Facilities or Significant Changes in
   Facility Operating Plans 1-2
  C. Make Knowledgeable and Responsible People Available for Sharing Information    1-5
  D. Provide Information About Facility Operations  1-6

III.  Understanding Risk Assessment     1-7
    A. Introduction to Risk Assessment  1-7
    B. Types of Risk    1-7
    C. Assessing Risk   1-9
        1.  Hazard Identification   1-10
        2.  Exposure Assessment: Pathways, Routes, and Estimation   1-10
        3.  Risk Characterization   1-14
    D. Results  :   1-15

IV.  Information on Environmental Releases  1-15

Building Partnerships Action Items  1-16

Resources   1-17

    Tablel: Effective Methods for Public Notification   1-3

    Figure 1: Multiple Exposure Pathways/Routes 1-11


                                                                  Getting Started—Building Partnerships
                     Building Partnerships
       Build a partnership through an active involvement program
       designed to build trust and credibility between a company that
       generates and manages waste, the community within which the
       company lives and works, and the state agency that regulates
       the industry.
          R:sidents 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 pub-
lic health or the environment.  Create opportu-
nities for dialogue between industries, states,
and concerned citizens before  decisions are
made. Partnership efforts also  need to be
ongoing in order to be successful.
 I.     Benefits of


  Building partnerships in the decision-mak-
 ing process provides a number of benefits:
 •  Enhanced understanding of waste man-
   agement activities at an industrial facility;
 •  Enhanced understanding of industry,
   state, and community concerns;
 •  Greater support of industry and state
 •  Reduced delays and costs associated with
   opposition and litigation;  and
 •  A positive image and relationship.
II.    Principles of


   Regardless of the size or type of an indus-
try waste unit, industries, states, and local
communities can all follow similar principles
of building partnerships. These principles are
based on various state public involvement
guidance documents, various EPA publica-
tions, and state requirements for waste facili-
ties. These principles embody sound business
practices and common sense, and may go
beyond state requirements that call for public
participation during the issuance of a permit.
This guidance document recommends princi-
ples that can be adopted throughout the oper-
ating life of facilities, not just during the per-
mitting process. Following these principles
  This chapter will help address the
  following questions:

  • What are the benefits of building

  • What building partnership methods
  have been successful?      ,

  • What is involved in preparing a


Getting Started—Building Partnerships
                   will help all involved consider the full range
                   of activities possible to give partners an active
                   voice in the decision-making process, and in
                   so doing, will result in a positive working
                   A.     Develop a  Partnership
                          Involvement Plan
                     The key to effective involvement, like any
                   activity, is good planning.  Developing a plan
                   for how and when to involve all parties in the
                   decision-making process will help to make
                   involvement activities run smoothly and
                   achieve the best results.  Developing an
                   involvement plan also helps identify concerns
                   and determine which involvement activities
                   best address those concerns.               .
                     The first step in developing an involve-
                   ment plan is to work with the state agency to
                   understand what involvement requirements
                   exist. (State contacts are provided in
                   Appendix I.) Existing state requirements deal-
                   ing with involvement plans must be followed.
                                           After this step, it
                                           will be important
                                           to assess how
                                           much interest
                                           facility activities
                                           will generate in
                                           the community.
                                           Several criteria
                                           influence the
                                           amount of public •
                                           interest, including
                                           implications for
                                           public health and
                   welfare, current relationships between the
                   facility and community members, and the
                   community's political and economic climate.
                   Even if facilities have not generated much
                   public interest in the past, involving the pub-
                   lic is a good idea. Interest in a facility can
                   increase suddenly when changes to existing
activities are proposed or when residents' atti-
tudes and a community's political or econom-
ic climate change over time.
  To gauge public interest in a facility and to
identify the community's major concerns,
industries can conduct interviews with com-
munity members. They can first talk with
representatives from major community
groups,  such as civic groups, religious organi-
zations, and business associations. If interest
in the facility seems  high, industries can con-
sider conducting a more comprehensive set of
community interviews. Other individuals to
interview may include the facility's immediate
neighbors, representatives from other agen-
cies and environmental organizations, and
any individuals in the community who  have
expressed interest in the facility.
  Using the information gathered during the
interviews, industries can develop a list of the
major community concerns regarding the
facility. They can then begin to engage in
involvement activities necessary to address
those concerns. These activities form the
basis of a partnership involvement 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 facilities and proposed changes gives
them the opportunity to identify applicable
state requirements and comment on matters
that apply to them.


                                                                          Getting Started—Building Partnerships
What are examples of effective
methods for notifying the public?
  Table 1 presents examples of effective meth-
ods for public notification and associated
advantages and disadvantages. The method
used at a particular site, and within a particu-
lar community, will depend on the type of
information or issues that need to be commu-
nicated and addressed. Public notices usually
provide the name and address of the facility
owner and operator and a brief description of
the change being considered. After a public
notice is issued, industries can develop infor-
mative 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
industry to answer questions.
                                        Table 1
                         Effective Methods for Public Notification
Methods Features Advantages Disadvantages I
i 1
Mailing of key technical
reports or environmental
News conferences
Newspaper inserts
Paid advertisements
News releases
Personal visit or phone call
to key officials or group lead-
ers 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 accompa-
nied by handouts of presenter's
Brief description of what is going
on, usually issued at key intervals
for all people who have shown
Much like a newsletter, but dis-
tributed as an insert in a news-
Advertising space purchased in
newspapers or on the radio or
A short announcement or news
story issued to the media to get
interest in media coverage of the
Provides background information.
Determines reactions before an issue
"goes public." Alerts key people to
issues that may affect them.
Provides full and detailed information
to people who are most interested.
Often increases the credibility of stu-
dies because they are fully visible.
Stimulates media interest in a story.
Direct quotes 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 dirough 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 ex-
tended technical studies.
Reaches the entire community with
important information. Is one of the
few mechanisms for reaching everyone
in the community dirough which you
can tell the story your way.
Effective for announcing meetings or
key decisions or as background materi-
al for future media stories.
Might stimulate interest from the media.
Useful for announcing meetings-or
omajor decisions or as background
material for future media stories.
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
quotes are likely.
Requires staff time. Costs
money to prepare, print and
mail. Stories must be
objective and credible, or
people will react to the news-
letters as if they were propa-
Requires staff time to prepare
the insert, and distribution
costs money. Must be prepared
to newspaper's layout
Advertising space can be cost-
ly. Radio and television may
entail expensive production
costs to prepare the ad.
Might be ignored or not read.
Cannot control how the infor-
mation is used.


Getting Started—Building Partnerships
                                                            Table 1
                                          Effective Methods for Public Notification (cont.)
Presentations to civic
and technical groups
Press kits
Advisory groups and
task forces
Focus groups
Telephone line
Deliver presentations, enhanced
with slides or overheads, to key
community groups.
A packet of information distribu-
ted to reporters.
A group of representatives of key
interested parties is established.
May be a policy, technical, or citi-
zen advisory group._
Small discussion groups
established to give "typical" reac-
tions of the public. Conducted
by a professional facilitator.
Several sessions may 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.
Advantages Disadvantages
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 constituents. Anticipates public
reaction to publications or decisions.
Provides a forum for reaching
Provides in-depth reaction to ideas or
decisions. Good for predicting emo-
tional 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 form for the public
to be heard on issues. Can be struc
tured to permit small group interac-
tion — anyone can speak.
Few disadvantages except
some groups can be hostile.
Few disadvantages except
cannot control how the infor-
is used and might not be
Potential for controversy exists
if "advisory" recommendations
are not followed. Requires
substantial commitment of
staff time to provide support
to committees.
Gets reactions, but no know-
ledge of how many people
share those reactions. Might
be perceived as an effort to
manipulate the public.
Is only as effective as the per-
son answering the telephone.
Can be expensive.
Unless a small group discuss-
ion format is used, it permits
only limited dialogue. Can
get exaggerated positions or
grandstanding. Requires
staff time to prepare for
                   U.S. EPA 1990. Sites for Our Solid Waste: A Guidebook for Effective Public Involvement.
                   What is involved  in preparing a
                   meeting with industry, communi-
                   ty, and state representatives?
                      Meetings can be an effective means of giving
                   and receiving comments and addressing con-
                   cerns. 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 dialogue, meetings
                   should be at times convenient for members of
                   the community, such as early in the evenings
                   during the week, or ori weekends. An interpreter
                   may need to be obtained (hire or seek a volun-
                   teer) if the local community includes residents
                   whose primary language is not English.
  Prior to a meeting, an industry should devel-
op a waste management plan for the facility or
come to the meet-
ing prepared to
describe how the
industrial waste
from the facility will
be managed. A
waste management
plan provides a
starting point for
public comment
and input. Keep
data presentations
simple  and provide
information relevant


                                                                           Getting Started—Building Partnerships
to the audience. Public speakers should be
able to respond to general questions, as well as
technical questions. Also, industry should
review and be familiar with the concerns of
groups or citizens who have previously
expressed an interest in the facility. In addi-
tion, it is important to anticipate questions and
plan how best to respond to these questions at
a meeting.
  State representatives should also be pre-
pared to answer questions that are anticipated
at the meeting. State representatives should
be prepared to answer questions on specific
regulatory or compliance issues, as well as to
address how the industry has been working
in cooperation with the state agency.
  Questions often asked at a meeting
•  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 bene-
    fit 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
•  How will the waste streams be treated or
•  What are the construction plans for any
    proposed containment  facilities?
•  What are the intended  methods for moni-
    toring and detecting emissions or poten-
    tial releases?
•  What are the plans to address accidental
    releases of chemicals or wastes at the site?
•  What are the plans for financial assur-
     ance, closure, and post-closure care?
•   What are the applicable state regulations?
•   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 concerns about the
   At the meeting, industry should invite
public and state comments on the proposed
change, and tell community members where,
and to whom they should send written com-
ments. Industry can choose to respond to
comments in several ways. For example, tele-
phone calls, additional fact sheets, or addi-
tional meetings can all be used to address
comments. Responding promptly to residents'
comments and concerns demonstrates an
honest attempt to address them.
C.     Make Knowledgeable
        and Responsible People
        Available for Sharing
   Having an industry contact(s) available to
answer the public's questions and provide
information helps assure citizens that the
industry is actively listening to their con-
cerns. Having a state contact available to
address the public's concerns about the facili-
ty can also make sure that concerns are being
heard and addressed.
   In addition to identifying a contact person,
industry and states should consider setting
up a telephone line, staffed by employees, for
citizens to call and obtain information
promptly about the facility. Opportunities for
face-to-face interaction between community
members and facility representatives include
onsite information offices, open houses,  ,
workshops, or briefings. Information offices
function similarly to information repositories,
except that an employee is present  to answer


Getting Started—Building Partnerships
                                              questions. Open
                                              houses are infor-
                                              mal meetings on-
                                              site where resi-  '
                                              dents can talk to
                                              company officials
                                              Similarly, work-
                                              shops  and brief-
                                              ings enable com-
                                              munity mem-
                                              bers, state offi-
                                              cials, and indus-
                                              try representa-
                    tives to interact, ask questions,  and learn
                    about the activities at the facility. Web sites
                    may also serve as a useful tool for industry,
                    state, and community representatives to share
                    information and ask questions.
                    D.     Provide Information
                            About  Facility
                       Providing information about site opera-
                    tions is an invaluable way to help the public,
                    understand waste management activities at a
                    site. Facility tours, maintaining a publicly
                    accessible information repository at the site,
                    developing exhibits to explain operations,
                    and distributing information through the
                    publications of established organizations are
                    examples that can serve to inform a commu-
                    nity. Appendix II describes some of the public
                    involvement activities that are being conduct-
                    ed by various companies around the country.
                       Conduct facility tours. Scheduled  facility
                    tours allow the community and state to visit
                    the facility and ask questions about how it
                    operates. By seeing a facility first-hand, resi-;
                    dents learn how waste is managed and can
                    become more confident that it is being man-
                    aged safely.  Individual citizens, 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 see-
ing, such as providing hands-on demonstra-
tions. It is also a good idea to have company
individuals available to answer technical
questions in an easy-to-understand manner.
   Maintain a publicly accessible information
repository. An information repository is simply
a collection of documents describing the facili-
ty and its activities. It can include background
information on the facility, the involvement
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 maintained on-
site in a public "reading room" or off-site at a
public library,  town hall, or public  health
office. Industry should publicize the existence,
location, and hours of the repository and
update the information regularly.
   Develop exhibits that explain facility oper-
ations. Exhibits are visual displays, such as
maps, charts, diagrams, or photographs,
accompanied by brief text. They provide
technical information in an easily  under-
standable way and give an opportunity to
illustrate issues of concern creatively and
informatively.  When developing exhibits,
identify the target audience, clarify which
issue or aspect of the facility's operations will
be the exhibit's 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 estab-
lished local organizations. Existing groups
and publications often provide access to
established communication networks. Take
advantage of these networks to minimize the


                                                                         Getting Started—Building Partnerships
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, or magazines, as well as mailing lists,
that could be useful in reaching interested
members of the community.
understand the nature of any uncertainties
associated with the analysis.  This section
provides a general overview of the scientific
principles underlying the methods for quanti-
fying cancer and noncancer risk assessment.
Ultimately, understanding the scientific prin-
ciples will lead to more effective use of the
guidance tools.
III.   Understanding

        Risk  Assessment
   Environmental risk communication skills
are critical to successful partnerships between
industry, the public, and other stakeholders.
As more environmental management deci-
sions are made on the basis of risk, it is
increasingly important for all interested par-
ties to understand the science behind risk
assessment. Encouraging public participation
in environmental decision-making means
ensuring that all interested parties understand
the basic principles of risk analysis and can
converse equally on the development of
assumptions that underlie the analysis.

A.     Introduction to Risk
   This guidance document provides simple-
to-use risk assessment tools that can assist in
determining the appropriate waste manage-
ment practices for surface impoundments,
landfills, waste piles, and land application
units. The guidance tools are based on pre-
dicting 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 applying
the guidance tools is simple, it is still essen-
tial to understand the basic concepts of risk
analysis to be able to interpret the results and
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 procedures. By definition, risk is
comprised of two components: the  probabili-
ty that an adverse event will occur and the
magnitude of the consequences of that
adverse event.  As such, in capturing these
two components, risk is typically stated in
terms of the probability (e.g., one chance in
one million) of a specific harmful "endpoint"
(i.e., accident,  fatality, cancer).
   In the context of environmental manage-
ment, and in the context  of this section in the
guidance document, risk is defined  as the
probability or likelihood that public health
may be impacted from exposure to  chemicals
contained in waste management units. The
risk endpoints resulting from the exposure are
typically grouped into two major consequence
categories: cancer risk and noncancer risk.
   As implied,  the cancer risk category cap-
tures risks associated with exposure to chemi-
cals that may initiate cancer. To determine a
cancer risk, one must calculate the probability
of an individual developing any type of cancer
during his or her lifetime from exposure to
carcinogenic hazards. Cancer risk is generally
expressed in scientific notation; in this nota-
tion, the chance of 1 person in 1,000,000 of


Getting Started—Building Partnerships
                   developing cancer would be expressed as
                   1 x lO^or IE6. The noncancer risk category is
                   essentially a catch-all category for the remain-
                   ing health effects resulting from chemical
                   exposure. Noncancer risk encompasses a
                   diverse set of effects  or endpoints, such as
                   weight loss, enzyme  changes, reproductive
                   and developmental abnormalities, and respira-
                   tory reactions. Noncancer risk is generally
                   assessed by comparing the exposure or aver-
                   age intake of a chemical with a corresponding
                   reference (a health benchmark), thereby creat-
                   ing 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
                   benchmark, whereas, an HQ less than 1 indi-
                   cates 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 (i.e., ingestion, inhalation) and dose
                   (the amount that a human  intakes) of the
                   exposure. Health benchmark values are used ;
                   to quantify a chemical's possible toxicity and
                   ability to induce a health effect, and are
                   derived from toxicity data.  They represent a
                   "dose-response" 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 i
                   (ingestion or inhalation) and the duration
                   (acute, subchronic, or chronic) of the expo-
                   sure. The definitions of acute, subchronic and
                   chronic exposures vary, but acute typically
implies an exposure of less than one day, sub-
chronic generally indicates an exposure of a
few weeks to a few months, and chronic
exposure can span periods of several months
to several years.
   The health benchmark for carcinogens is
called the cancer slope factor. A cancer slope
factor (CSF) is defined as the upper-bound
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)'1. The slope
factor is used to  estimate an upper-bound
probability of an individual developing can-
cer 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
sensitive populations) that are likely to be
without 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, and nutritionally or immunologically
  Example of Health Benchmarks
      inhalation CFS: 0.24(mg/kg/d)4
      oral CFS: 0.54 (mg/kg/d)-1
      RIG: 0.002 mg/rn3
      R£D:0.001 mg/kg/d
      RfC: 0.02 mg/m'
      ATSDR MRL: 0.22 mg/m3


                                                                                 Getting Started—Building Partnerships
compromised) to the effects of
hazardous substances. There is
additional uncertainty because
most benchmarks must be based
on studies performed on animals,
as relevant human studies are
  There are several sources for
obtaining health benchmarks,
some of which are summarized in
the text box. Note that from time-
to-time benchmark values may be
revised to reflect new toxicology
data on a chemical. In addition,
because many states may have
developed their own toxicology
benchmarks, both the ground-
water and air tools in this guid-
ance enable a user to input an
alternative benchmark to those
that are provided.
 C.     Assessing Risk
   Typically risk is estimated using
 the organized process of evaluat-
 ing scientific data known as risk
 assessment. Risk assessment ulti-
 mately serves as guidance for
 making management decisions by
 providing one of the inputs to the
 decision making process. Risk
 assessment furnishes beneficial
 information for a variety of situa-
 tions, such as determining the
 appropriate pollution control sys-
 tems for an industrial site, pre-
 dicting the appropriateness of dif-
 ferent waste management options
 or alternative waste management
 unit configurations, or identifying
 exposures that may require addi-
 tional attention.
           Sources for Health Benchmarks
                         System (IRIS) The Integrated
Risk Information System (IRIS) is the Agency's official, reposi-
tory of Agency-wide consensus chronic human health risk
information. IRIS-is an EPA data base containing Agency con-
sensus scientific positions on potential adverse human health
effects that may result from'chronic (or lifetime) exposure to  .
environmental contaminants. IRIS information includes the
reference dose for rioncancer'health effects resulting from
oral exposure, the.reference concentration for noncancer  .
health effects resulting from inhalation exposure, and the car-
cinogen assessment for both oral and inhalation exposure.
Health Effects Assessmem Sumniary Tables (HEAST)
HEAST  is a comprehensive listing compiled by the EPA ,  .,
consistmg'of risk assessment -information relative to  oral
and inhalation routes for chemicals.  HEAST benchmarks
are considered secondary to those contained in IRIS.
Although the  entries in HEAST have undergone review and
have the concurrence of individual agency program  offices,
they have either not been reviewed as extensively as those
in IRIS or they dp, not have as complete a data set as is
.required for acchemical to be listed in IRIS.
Agency for Toaac Substances and Disease Registry (ATSPK)
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 priority, a list of
hazardous substances most commonly found at facilities on
the CERCLA National Priorities List; prepare lexicological
profiles  for each substance included on the priority list of
hazardous substances; ascertain significant human exposure
levels (SHELs) for hazardous substances in the environment,
and the associated acute, subchronic, and chronic health
effects; and assure the initiation of a research program to fill
identified 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 non-
cancer health effects only and are not based on a considera-
tion of cancer effects. MRLs are derived for acute (1-14 days),
intermediate (15-364 days), and.chronic (365 days and
longer) exposure durations, for the oral and inhalation routes
of exposure.


Getting Started—BuzMing Partnerships
                      The risk-evaluation process involves data
                   collection activities, such as identifying and
                   characterizing the source of the environmen-
                   tal pollutant, determining the transport of
                   the pollutant once it is released into the
                   environment, determining the pathways of
                   human exposure, and identifying the extent
                   of exposure for individuals or populations at
                   risk. Performing a risk assessment is complex
                   and requires knowledge in a number of sci-
                   entific disciplines. Experts in several areas,
                   such as toxicology, geochemistry, environ-
                   mental engineering, and meteorology, may be
                   involved in performing a risk assessment.
                   For the purpose of this section, and for
                   brevity, the basic components 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 references listed at the
                   end of this section.
                      The three main categories are:
                      1.    Hazard Identification: identifying and
                           characterizing1 the source of the
                           potential risk (e.g., chemicals man-
                           aged in a waste management unit).
                       2.  Exposure Assessment: determining  ,
                           the accessibility or avenues from the
                           source to an individual (i.e., exposure
                           pathways and,exposure routes).
                       3.  Risk Characterization: integrating the
                           results of the exposure assessment
                           with information on who is potential-
                           ly at risk (e.g.,  location of the person,
                           body weights, etc.) and toxicity infor-
                           mation on the chemical.
                    1.     Hazard  Identification
                      For the purpose of this guidance docu-
                    ment, the source of the potential risk has
                    already been identified: waste management
                    units. However, there must be a release of
                    chemicals from a waste management unit for:
there to be exposure and risk. Chemicals may
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
chemicals travel through the ground to a
ground-water aquifer), particulate emission
(where chemicals attached to particulate mat-
ter are released in the air when the particulate
matter becomes airborne), and run-off and
erosion (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 tend to pro-
duce larger releases. Units located close to the
water table might produce greater releases to
ground water than units located further from
the water table.  Units located in a hot, dry,
windy climate may produce greater volatile
releases than units in a cool, wet, non-windy
2.      Exposure Assessment:
        Pathways, Routes,  and
  Individuals and populations may come
into contact with environmental pollutants by
a variety of exposure mechanisms and
processes. The mere presence of a hazard,
such as toxic  chemicals in a waste manage-
ment unit, does not denote the existence of a
risk. Exposure is the bridge between what is
considered a hazard and what actually pre-
sents a risk. Assessing exposure involves
determining the pathways and extent of
human contact with toxic chemicals. 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.


                                                                            Getting Started—Building Partnerships
  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 receptor's exposure time,
frequency and duration. The output of the
exposure assessment is a numerical estimate of
exposure and intake of a chemical by an indi-
vidual. The intake information is then used in
concert with chemical-specific health bench-
marks 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 may 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, meteorological condi-
tions, ground-water pH, and loca-
tion of the nearest receptor.
Information must be gathered for
the two components of exposure
assessment: exposure
pathways/routes and exposure
  a.    Exposure
   An exposure pathway is the
course the chemical takes from its
source to the individual or popula-
tion 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 pathway depends on the concentra-
            tion of a chemical in the relevant medium and
            the rate of intake by the exposed individual. In
            a comprehensive risk assessment, the risk
            assessor identifies all possible site-specific
            pathways through which a chemical could
            move and reach a receptor. This guidance doc-
            ument provides tools to model the transport
            and movement of chemicals through two envi-
            ronmental 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
Figure 1. Multiple Exposure Pathways/Routes (National Research
Council, "Frontiers in Assesssing Human Exposure," 1991)


Getting Started—Building Partnerships
                     water and ground water are car-
                     ried by water currents or sedi-
                     ments suspended in the water.
                     The chemistry of the contami-
                     nants and of the surrounding
                     environment, often referred to as
                     the "system," also plays a signifi-
                     cant role in determining the ulti-
                     mate distribution of pollutants in
                     the various types of media.
                     Physical-chemical processes,
                     including dissolution/precipita-
                     tion, volatilization,  and photolytic
                     and hydrolytic degradation, as
                     well as sorption and complexa-
                     tion, can influence  the distribu-
                     tion of chemicals among the dif-
                     ferent environmental media and
                     the transformation  from one
                     chemical form to another.1 An
                     important component of creating
                     a conceptual model for perform-
                     ing 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.
                        Whereas  the exposure pathway
                     dictates the  means  by which a
                     contaminant can reach an indi-
                     vidual, the exposure route is the
                     way in which that chemical enters
                      the body. To generate a health
                      effect, the chemical must come in
                      contact with the body. In environ-
                      mental risk assessment, three
                      exposure routes are generally con-
                      sidered: ingestion,  inhalation, and
                      dermal absorption. As stated ear-
                      lier, the toxicity of a chemical is
                      specific to the dose received and
                      its means of entry into the body.
                      For example, a chemical that is
                      inhaled may prove to be toxic and
               Key Chemical Processes

Sorption: the ability of a-chemical to partition between the
liquid and solid phase by determining its affinity for adher-
ing to other solids in the system such as soils and sediment.
The amount of chemical that "sorbs" to solids and does not
move through the environment is dependent upon the char-
acteristics of the  chemical, the characteristics of the sur-
rounding soils and sediments, and the quantity of the chemi-
cal. A sorption coefficient is the measure of a chemical's abili-
ty to sorb. If too much of the chemical is present, the avail-
able binding sites on soils and sediments will be filled and
sorption will not continue.

DissolMon/prec^itation: the extent to which a substance
will be found in  a soluble form versus a solid form. In disso-
lution a chemical is taken into solution; precipitation is the
formation of an insoluble solid. These processes are a func-
tion of the nature of the chemical and its surrounding envi-
ronment and are dependent on properties such as tempera-
ture and pH. A chemical's solubility is characterized by a sol-
ubility product. Chemicals that tend to volatilize rapidly are
not highly soluble.
Degradation: the propensity and extent a chemical will break
down into other substances in the environment. Some degra-
dation processes include biodegradation, hydrolysis, and
photolysis. Not all degradation products have the same risk
as the "parent" compound. Some chemicals can break into
"daughter" products that are more harmful than the parent
substance. In performing a risk assessment it is important to
consider what the daughter products of degradation may be.

Bioaccumulation: the ability of a substance to be taken up
and stored in an organism. Typically, the concentrations of
the substance in the organism exceed the concentrations in
the environment since the organism will store the substance
and not excrete  it. A bioaccumulation factor is associated
with each chemical.

Volatility: the ability of a compound to partition 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 Rauok's Law. Other factors that are
important to volatility are atmospheric temperature and
waste mixing.
                      'Kolluru, Rao (1996)


                                                                             Getting Started—Building Partnerships
result in a harmful health effect, whereas the
same chemical may cause no reaction if
ingested, or vice-versa. This phenomenon is
due to the differences in mechanisms once a
chemical enters the body. A chemical that is
inhaled reaches the lungs and enters the
blood system. A chemical that is ingested
may pass through the liver  before entering
the blood system, where it  may be metabo-
lized into a different chemical that may result
in a health effect or into another chemical
that  is soluble 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. However, some
chemicals can pass through the skin in suffi-
cient 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 this guidance docu-
ment do not address the dermal  route of
  b.    Exposure
   Once appropriate fate and transport mod-
eling has been performed for each pathway,
providing concentrations of a chemical at an
exposure point, the chemical intake by a
receptor must be quantified. Quantifying the
frequency, magnitude, and duration of expo-
sures 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  expo-
sures 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 kilogram
body weight per day, also expressed as
   The exposure quantification process
requires two main areas of information gather-
ing: the receptor activity patterns and the bio-
logical characteristics of receptors (body
weight, inhalation rate). Activity patterns and
biological characteristics dictate the amount of
a constituent that a receptor may 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, expo-
sure  frequency,  exposure duration, body
weight, and exposure averaging time.  The val-
ues 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 may 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 may live in
the area for 20 years and be in the area for
more than 350  days each year. Conversely, an
area  visitor or a worker will have shorter
exposure times. After the intake values have
been estimated, they should be organized by
population as appropriate (i.e., 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
exposures; otherwise, default values suggested


Getting Started—Building Partnerships

                    by the EPA in The Exposure Factors Handbook
                    (EPA, 1995) may be used.
                    3.      Risk  Characterization
                      In the risk-characterization process, the toxi-
                    city information (slope factors, reference doses)
                    and the results of the exposure assessment
                    (estimated intake or dose of 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 toxic-
                    ity values. To characterize potential carcino-
                    genic effects, probabilities that an individual
                    will develop cancer over a lifetime are estimat-
                    ed from projected intake levels and chemical-
                    specific dose-response relationships. This pro-
                    cedure is the final calculation step. This step
                    determines who is likely to be affected and
                    what the likely affects are. Because of all the
                    assumptions inherent in deriving a risk, a risk,
                    characterization cannot be considered com-
                    plete unless the numerical expressions of risk
                    are accompanied by explanatory text interpret-
                    ing and qualifying the results. The risk charac-
                    terization step for carcinogens and noncarcino-
                    gens is different and is shown in the text box
                       Another consideration during the risk-
                    characterization phase are cumulative effects.
                                  Calculating Risk
                       Cancer Risks:
                       Incremental risk of cancer = average
                       daily dose (mg/kg-day) *  slope factor
                       Non-Cancer Risks
                       Hazard quotient = exposure or intake
                       (mg/kg-day) or (mg/m3)/ RfD (mg/kg-day)
                       or RfC (mg/m3)
A given population may be exposed to multi-
ple chemicals from several exposure routes
and sources. For example, multiple con-
stituents may be managed in a single waste
management unit, and by considering one
chemical at a time the risks associated with
the waste management unit may be underes-
timated. The EPA (1989a) has developed
guidance outlined in the Risk Assessment
Guidance for Superfund, Volume I to assess the
overall potential for cancer and noncancer
effects posed by multiple chemicals. The risk
assessor, facility manager, and other interest-
ed parties should determine the appropriate-
ness of adding the risk contribution of each
chemical for each pathway to derive a cumu-
lative cancer risk or noncancer risk. The pro-
     Cancer Risk Equation for Multiple
              Riskr = ZRisk,
  Riskr _ tne lotaj cancer risk, expressed as a
  unitless probability
  Risk. = the risk estimate for the ilh substance
 cedures for adding risks differ for carcino-
 genic and noncarcinogenic effects.
   The cancer-risk equation described in the
 box above estimates the incremental individ-
 ual lifetime cancer risk for simultaneous expo-
 sure to several carcinogens and is based on
 EPA (1989a) guidance. The equation com-
 bines risks by summing the risks to a receptor
 from each  of the carcinogenic chemicals.
   To assess the overall potential for noncar-
 cinogenic effects posed by more than one
 chemical, a hazard index (HI) approach was
 developed by the EPA. The approach
 assumes that the magnitude of an adverse
 health effect is proportional to the sum of the
 hazard quotients of each of the chemicals


                                                                           Getting Started—Building Partnerships
investigated. Assessing cumulative effects
from noncarcinogens is more difficult and
contains a greater amount of uncertainty. As
discussed earlier, noncarcinogenic risk covers
a diverse set of health effects and different
chemicals will have different effects. In keep-
ing with EPA's Risk Assessment Guidance,  haz-
ard quotients should only be added for
chemicals that have the same critical effect
(e.g., both chemicals effect the liver or both
initiate respiratory distress.)  As a result, an
extensive knowledge of toxicology 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 associated with it.
This analysis is not simple and should be per-
formed by a toxicologist.
D.    Results
   The results of a risk assessment provide a
basis for making decisions but are only one ele-
ment of input into  the decision process. The
risk assessment 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 assumptions that
were applied during the risk assessment.
Ample documentation should be constructed
to define the scenarios that were evaluated for
the risk analysis and any uncertainties there
may be in the estimate. Some of the informa-
tion that should be considered for inclusion in
the risk assessment documentation may be: key
site-related information such as contaminants
evaluated, a description of the risks present
(i.e., cancer, noncancer), the level of confidence
in the information used in the assessment, the
major factors driving  the site risks,  and the
characteristics of the exposed population. The
results of a risk assessment are essentially
meaningless without the information on how
they were generated.
IV.   Information on


   Under the Emergency Planning and
Act (EPCRA) of
1986, facilities
in a designated
Industry Code
(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 Toxic Release
Inventory (TRI)-listed chemical are required to
report their environmental releases annually to
EPA and state governments. Environmental
releases  include the disposal of wastes in land-
fills, surface impoundments, land application
units, and waste piles. EPA compiles these data
in the TRI database. TRI data are also being
made available through public libraries and
reports.  You may wish to include TRI data in
the facility's information repository.
   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 EPA's Web site


Getting Started—Building Partnerships

                             Building  Partnerships Action  Items
Develop exhibits that provide a better understanding of facility operations.

Identify potentially interested/affected people.

Notify the state and public about new facilities or significant changes in facility
operating plans.

Set up a public meeting for input from the community.

Provide interpreters for public meetings.

Make knowledgeable and responsible people available for sharing information.

Develop an involvement plan based on information gathered in previous steps.

Provide access to the facility and to information about its operations.

Maintain a publicly accessible information repository or on-site reading room.


                                                                          Getting Started—Building Partnerships
Chemical Manufacturers Association. 1994-1995. Ten Elements of Responsible Care:
Understanding the Initiative Through Member and Partner Progress.

Chemical Manufacturers Association. 1995.  A Plant Manager's Introduction to Environmental

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, Health, 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

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. 1996.  RCRA Public Involvement Manual. EPA530-R-96-007.

U.S. EPA. 1996.  1994 Toxics Release Inventory: Public Data Release, Executive Summary.


Getting Started—Building Partnerships
                                            Resources  (cont.)
            U.S. EPA. 1995.  Decision-maker's Guide to Solid Waste Management, Second Edition. EPA530-R-95-023.

            U.S. EPA. 1995. The Exposure Factors Handbook. EPA600-P-95-002A-E.

            U.S. EPA. 1995. 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-

            U.S. EPA. 1989. Chemical Releases and Chemical Risks: A Citizen's Guide to Risk Screening.

            U.S. EPA. 1989. 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.


       Part I
   Getting Started

     Chapter 2
Characterizing Waste


I. Waste Characterization Through Process Knowledge '.  2-1

II.  Waste Characterizaton Through Leachate Testing 2-2
    A. Sampling and Analysis Plan.  2-3
        1.  Representative Waste Sampling   2-4
        2.  Representative Waste Analysis   ,   2-6
    B. Leachate Test Selection      2-6
        1.  Toxicity Chracteristics Leaching Procedure  :   2-7
        2.  Synthetic Precipitation Leaching Procedure (SPLP)   2-8
        3.  Multiple Extraction Procedure (MEP) 2-9
        4.  Shake Extraction of Solid Waste with Water or Neutral Leaching Procedure    2-9

HI. Waste Characterizaton of Volatile Organic Emissions 2-10

Waste Characterizaton Action Items  2-11

Resources   :   2-12


                                                                   Getting Started—Characterizing Waste
                     Characterizing Waste
      Understand the industrial processes that generate a waste.
      Determine the waste's physical and chemical properties. Quantify
      constituent leaching to facilitate ground-water risk analysis.
      Quantify total constituent concentrations to facilitate air emission
      analysis, and consideration of pollution prevention and treatment.
           Understanding the physical and
           chemical properties of a waste
           and sampling and analysis proce-
           dures is the cornerstone upon
           which subsequent steps in this
guidance are built. Knowledge of the physical
and chemical properties of the waste is crucial
in identifying waste reduction opportunities. It
is necessary in gauging what risks a waste may
pose to surface water, ground water, and air. It
drives the selection of a liner or the choice of
land application methods. It is needed to deter-
mine which constituents to test for if conduct-
ing ground-water monitoring. Use knowledge
of waste generation processes, analytical testing,
or some combination of the two to estimate
waste constituent concentrations. Over time
when changes are made to the industrial
processes or waste management practices, it
  This chapter will help address the
  following questions:
  • Can process knowledge be used to char-
  acterize waste?
  • What constituent concentrations
  should be quantified?,
  • What type of leachate test should be
  used?     '• ""•  "•'-,, :
may be necessary to recharacterize a waste. No
matter which approach is used in characterizing
a waste, the important goal is to maximize the
knowledge available to make the important
decisions described in later chapters of this
I.     Waste
       Through Process
  A waste characterization begins with an
understanding of the industrial processes that
generate a waste. As a starting point, obtain
information about the waste itself such as the
physical state of the waste, the volume, and
the composition. In addition, obtain enough


  Getting Started—Characterizing Waste
                     information about the process to enable prop-
                     er characterization of the waste. Many indus-
                     tries have thoroughly tested and characterized
                     their wastes over time. Check with trade
                     associations to see if the appropriate informa-
                     tion is available for a particular waste.
                       The following examples of process knowl-
                     edge may assist in waste characterization by
                     providing information on waste constituents
                     and potential concentrations:
                     •   Chemical engineering designs/plans for  .
                         the process, showing process input chem-
                         icals, expected primary and secondary
                         chemical reactions, and products;
                     •   Material Safety Data Sheets (MSDSs).
                         Note, however, that not all MSDSs con-
                         tain information on all constituents  found
                         in a product;
                     •   Manufacturer's literature;
                     •   Previous waste analyses;
                     •   Literature on similar processes; and
                     •   Preliminary testing results, if available.
                       A materials balance exercise using process :
                     knowledge may be useful in understanding
                     where wastes are generated within a process,
                     and estimating the quantity of chemicals in
                     such wastes. In a material balance, calculate
                     all input streams, such as raw materials fed
                     into the processes, and all output streams,
                     such as  products produced and waste gener-
                     ated. Material balances can assist in estimat-
                     ing concentrations of waste constituents
                     where analytical test data are limited.
                     Characterizing waste using material balances
                     can require considerable effort and expense,
                     but may assist in developing a more complete
                     picture  of candidate waste generation
                     process(es).  Flow diagrams  are generally pre-
                     pared to identify important process steps and
                     sources where wastes are generated.
                        A thorough assessment of a production
processes can also serve as the starting point
for a facility-wide waste reduction, recycling,
or pollution prevention effort. Such an assess-
ment will provide the information base to
explore many opportunities to reduce or
recycle the volume or toxicity of wastes.
Check the integrating pollution prevention,
recycling, and treatment chapter for ideas,
tools, and references on how to proceed.
II.   Waste
       Leachate Testing
   The intent of leaching and extraction tests is
to estimate the release of waste constituents
into ground water. The importance of estimat-
ing potential constituent concentrations that
may leach to ground water is underscored by
the fact that the ground water software model,
Industrial  Waste Management Evaluation Model,
(IWEM),  developed for this guidance docu-
ment uses expected leachate concentrations to
develop recommended liner system designs.
   If the total  concentration of all the con-
stituents  in a waste, has been estimated using
process or industry knowledge, 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)
does allow for a total constituent analysis in
lieu of the TCLP extraction. If a waste is 100
percent solid, as defined by the TCLP
method,  then the results of the total composi-
tional analysis may be divided by twenty to
convert the total results into the maximum
leachable concentration. This factor is derived
from the  20:1 liquid to solid ratio employed
in the TCLP. If a waste has filterable liquid,


                                                                            Getting Started—Characterizing Waste
then the concentration of each phase (liquid
and solid) must be determined. The following
equation may be used to calculate this value:1
          [A x B] + [C x D]
         B + [20 (L/kg) x D]
  A = Concentration of the analyte in liquid
  portion of the sample (mg/L)
  B = Volume of the liquid portion of the sam-
  ple (L).
  C = Concentration of the analyte in solid
  portion of the sample (mg/kg)
  D = Weight of the solid portion of the sam-
  ple (kg)
  E = Maximum theoretical concentration in
  leachate (mg/L)
Because this is only a screening method for
identifying an upper-bound TCLP leachate
concentration, consult with the state agency to
determine whether process knowledge can be
used in lieu of leachate testing.

A.     Sampling  and Analysis
   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
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 opportuni-
ty for error or misunderstanding during sam-
pling, analysis, and data treatment.
   To ensure that the sampling plan is
designed properly, a wide-range of personnel
should be consulted. The end user of the data,
an experienced member of the sampling team,
a senior analytical chemist, an engineer who
understands the manufacturing processes, a
statistician, and a quality assurance represen-
tative all need to be involved in the develop-
ment of a sampling plan. It is also wise to
consult the analytical laboratory to be used.
Development of sampling plans requires back-
ground information about the waste and the
unit, knowledge of the waste location and sit-
uation, decisions as to the types of samples
needed, and decisions as to the sampling
design required. The plan should address the
following considerations:
•  Data quality objectives;
•  Determination of a representative sample;
•  Statistical methods to be employed in the
•  Waste generation and handling processes;
•  Constituents/parameters  to be sampled;
•  Physical and chemical properties of the
•  Accessibility of the unit;
•  Sampling equipment, methods, and sam-
    ple containers;
•  Quality assurance and quality control
    (e.g., sample preservation and handling
•  Chain-of-custody; and
•  Health and safety of employees.
   A number of these factors 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,  Guidance for the Data Quality
Objectives Process (EPA600-R-96-055), Guidance
on Quality Assurance Project Plans (EPA600-R-
98-018), and Guidance for the Data Quality
Assessment: Practical Methods for Data Analysis
 'SW-846 Methods Team Home page at <www.epa.gov/sw-846/faqs>.


Getting Started—Characterizing Waste
                      Prior to implementing a sampling
                   plan, it is often strategic to walk
                   through the sampling plan mentally,
                   starting with the preparation of the
                   equipment through the time when
                   samples are received at the laborato-
                   ry. This mental excursion should be
                   in as much detail as can be imag-
                   ined, because the small details are
                   the ones most frequently over-
                   1.      Representative
                           Waste Sampling
                      The first step in any analytical
                   testing process is to obtain a sample
                   that is representative of the physical
                   and chemical composition of a
                   waste. The term "representative
                   sample" is commonly used to
                   denote a sample that has the proper-
                   ties and composition of the popula-
                   tion from which it was collected and
                   in the same proportions as found in
                   the population. This can be mislead-
                   ing unless dealing with a homoge-
                   nous waste from which one sample
                   can represent the whole population.
                   Because most industrial wastes are
                   not homogeneous, many different
                   factors should be considered in
                   obtaining samples that are collec-
                   tively representative of a waste.
                   Examples of 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, gas, solid, or multipha-
                       sic. It will also vary according to
                       whether the liquid is viscous  or
                       free-flowing, or whether the solid
  More Information on Test Methods for Evaluating
  Solid Waste, Physical/Chemical Methods—SW-846
EPA has begun replacing requirements mandating the
use of specific measurement methods or technologies
with a performance-based measurement system
(PBMS). The goals of PBMS is to reduce regulatory
burden and foster the use of innovative and emerging
technologies or methods. PBMS establishes what
needs to be accomplished, but does not prescribe
specifically how to do it. In a sampling situation, for
example, PBMS would establish the data needs, the
level of uncertainty acceptable for making decisions,
and the required supporting documentation, a specific
test method would not be prescribed. This approach
allows the analyst the flexibility to select the most
appropriate and cost effective test methods or tech-
nologies to comply with the criteria. Under  PBMS, the
analyst is required to demonstrate the accuracy of the
measurement method using the specific matrix that is
being analyzed. SW-846 serves only as a guidance
document and starting point,

SW-846 provides state-of-the-art analytical test meth-
ods for a wide array of inorganic and organic con-
stituents, as well  as procedures for field and laborato-
ry quality control, sampling, and characteristics test-
ing. The methods are intended to promote accuracy,
sensitivity, specificity, precision, and comparability of
analyses and test results.

For assistance with the methods described in SW-846,
call the EPA Method Information Communication
Exchange (MICE) Hotline at 703 821-4690 or send
an e-mail to mice@lan828.ehsg.saic.com.

SW-846 is available on line at:
A hard copy or CD-ROM version of SW-846 can be
purchased by calling the National Technical
Information Service (NTIS) at 703 487-4808.


                                                                            Getting Started—Characterizing Waste
    is hard or soft, powdery, monolithic, or
•   Composition of the waste. The samples
    should represent the average concentra-
    tion and variability of the waste in time
    or over space.
•   Waste generation and handling processes.
    The waste generation and handling
    processes to account for in sampling
    efforts include: if the waste is generated
    in batches; if there is a change in the raw
    materials used in a manufacturing
    process; if waste  composition can vary
    substantially as a function of process
    temperatures or pressures; and if storage
    time after generation may vary.
•   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 unknow-
    ingly collected at one of these intervals,
    incorrect conclusions could be drawn.
   Consult with the state agency to identify any
legal requirements or preferences before begin-
ning sampling efforts. Refer to Chapter 9 of
SW-846 for detailed guidance on planning,
implementing, and assessing sampling events.
To ensure that the chemical information
obtained from a  waste sampling efforts is accu-
rate, it must be unbiased and sufficiently pre-
cise. Accuracy is usually achieved by incorpo-
rating some form of randomness into the sam-
ple selection process  and by selecting an appro-
priate number of samples. Since most industri-
al wastes are heterogeneous 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 (essential-
ly all locations 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 sufficiently precise estimate of the
true mean concentration of a chemical conta-
minant in a waste. A number of mathematical
formulas exist for determining the appropri-
ate number of samples depending on the sta-
tistical precision required.

   The type of sampling plan developed will
vary depending on the sampling location.
Solid wastes contained in a landfill or waste
pile may 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 semisolid
wastes in surface impoundments, then a two-
dimensional simple random sampling strategy
may be appropriate. In this strategy, the top
surface of the waste is divided into an imagi-
nary grid, grid sections are  selected using ran-
dom-number tables  or random-number gener-
ators, and each selected grid point is  then sam-
pled 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  due to the
size of the impoundment, the sampling strategy
should, at a minimum, take sufficient samples
to address the potential vertical anomalies in
the waste  in order to be considered representa-
tive. This is because contained wastes tend to
display vertical, rather than horizontal, nonran-
dom heterogeneity due to settling of suspended
solids or denser liquid phases.


Getting Started—Characterising Waste
                      To facilitate characterization efforts, con-
                    sult with the state agency and a qualified pro-
                    fessional to select a sampling plan and deter-;
                    mine the appropriate number of samples,
                    before beginning sampling efforts. Consider
                    conducting a waste-stream specific characteri-
                    zation in sufficient detail so that the informa-
                    tion can be used to conduct waste reduction ]
                    and waste minimization activities.
                      Additional information concerning sampling
                    plans, strategies, methods, equipment, and
                    sampling quality assurance and quality control
                    is available in chapters'9 and 10 in SW-846.
                    Electronic versions of these chapters have been
                    included on the CD-ROM for this guidance.
                    2.     Representative Waste
                      Once a representative sample has been col-
                    lected, it must be preserved to maintain the
                    physical and chemical properties that it pos-
                    sessed at the time of collection. Sample types,
                    types of sample containers, and their prepara-
                    tion and preservation methods are all impor-
                    tant in maintaining the integrity of the  sam-  ;
                    pie. The analytical chemist must develop an
                    analytical plan which is appropriate for the
                    sample to be analyzed, the constituents/para-
                    meters to be analyzed for, and the end  use of
                    the information required. SW-846 contains
                    information on analytical plans and methods.
                    Additional references exist that are useful
                    sources of information regarding the selection
                    of analytical methods and quality
                    assurance/quality control procedures for vari-
                    ous compounds. One such web site is

                      B.  Leachate Test Selection
                      Leaching tests are used to estimate potential
                    concentration or amount of waste constituents
that may 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 constituent concentrations.
The type of leaching test performed may vary
depending on the chemical, biological, and
physical characteristics of the waste, the envi-
ronment in which the waste will be placed, as
well as the recommendations or requirements
of the state agency
   When selecting  the most appropriate ana-
lytical procedures,  consider at a minimum
the physical state of the sample using process
  What leachate test is appropriate?
  Selecting an appropriate leachate test can
  be summarized in the following four steps.
  1.  Assess the physical state of the waste
     using process and generator know-
  2.  Assess the environment in which the
     waste will be placed.
  3.  Consult with the state agency.
  4.  Select an  appropriate leachate test
     based on  the above information.
and generator knowledge, the constituents to
be analyzed, detection limits, and the speci-
fied holding times of the analytical methods.
It may not be cost-effective or useful to con-
duct a test with detection limits at or greater
than the constituent concentrations in a
waste. 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.
Select a procedure that is designed for the
specific sample type.
  After assessing the state of the waste, assess
the environment in which the waste will be


                                                                            Getting Started—Characterizing Waste
placed. For example, an acidic environment
may require a different test than a non-acidic
environment. If the waste management unit is
receiving only monofill, then the characteris-
tics of the waste will determine most of the
unit's conditions.  Conversely, if wastes are
being co-disposed, then the conditions creat-
ed by the co-disposed wastes must be consid-
ered, including the constituents that may be
leached by the subject waste.
   As described in the Phase IV LDR rule-
making (62 FR 25997; May 26, 1998), EPA is
undertaking a review of the TCLP test and
how it is used to evaluate waste leaching. EPA
anticipates that this review will examine the
effects of a number of factors on leaching and
on approaches to estimating the likely leach-
ing of a waste in the environment. These fac-
tors 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 may or may not
be well reflected in the leaching tests current-
ly available. At the conclusion of the TCLP
review, EPA is likely to issue revisions to this
guidance that reflect a more complete under-
standing of waste constituent leaching under
a variety of management conditions.
   Use a qualified laboratory when conduct-
ing analytical testing. The laboratory may be
in-house or independent.  When using inde-
pendent laboratories, ensure that they are
qualified and competent to perform the
required tests. Some laboratories may be pro-
ficient in one test but not another. Consult
with the laboratory before finalizing the test
selection to ensure that it can  be performed.
When using analytical tests  that are not fre-
 quently performed, additional quality assur-
 ance and quality control practices may be
necessary to ensure that the tests were con-
 ducted correctly and that the results are accu-
  A brief summary of the TCLP and three
other commonly used leachability tests is
provided below. The complete procedures for
all of these tests are included in SW-846 or in
the Annual Book ofASTM Standards Volume
11.04. Appendix I provides a summary of
over 20 tests designed to help determine the
potential for contaminant release.2 Consult
with the state agency to identify the most
appropriate test and test procedures for the
waste and sample type.
 1.     Toxicity  Characteristic
       Leaching  Procedure
   The TCLP is the test required to determine
whether a waste is a toxicity characteristic
hazardous waste under RCRA in 40 CFR Part
261. The TCLP estimates the leachability of
certain hazardous constituents from solid
waste under a defined set of laboratory con-
ditions. 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 con-
stituents into ground water under conditions
found in municipal solid waste (MSW) land-
 fills. The TCLP does not simulate the release
 of contaminants to nonground-water path-
ways. The TCLP is most commonly used by
 EPA and state agencies to evaluate the leach-
 ing potential of wastes, and to estimate likely
 risks to ground water. The TCLP can be
 found as EPA Method 1311 in SW-846.3 A
 copy of Method 1311 has been included on
 the CD-ROM for this guidance.
   In the TCLP, liquid wastes (those contain-
 ing less than 0.5 percent dry solid material)
 are filtered through a glass  fiber filter.  Waste
 samples containing solids and liquids  are
 handled by separating the liquids from the
 solid phase, and then reducing solids  to par-
 ticle size.  The solids  are then extracted with
 an acetate buffer solution. A liquid-to-solid
2EPA has only reviewed and evaluated those test methods found in SW-846. EPA has not reviewed or evalu-
ated the other test methods and cannot recommend any test methods other than those found in SW-846.

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
                   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 filtrate and
                   leachate to determine the constituent concen-
                   trations. If the extract contains any of the
                   constituents listed in Table 1 of 40 CFR Part
                   261.24 at a concentration equal  or greater
                   than the respective value in the Table, unless
                   excluded under §261.4, then the waste is
                   considered to be a hazardous waste under the
                   Toxicity Characteristic (TC).
                      Check with the state agency to determine
                   whether the TCLP is likely to be the best test
                   for evaluating the leaching potential of a .
                   waste, or if another test may better predict
                   the actual leaching of a waste. The TCLP test,
                   like other available leach tests, is designed to
                   simulate, or approximate one set of disposal
                   conditions and waste leaching that might
                   occur under those conditions. It is used by
                   EPA to classify waste as hazardous, and may
                   be conservative in some^ conditions (although
                   it has also apparently under predicted leach-
                   ing in other, rather extreme, conditions).
                   When disposal conditions are very different
                   from the TCLP test conditions, another test
                   may provide better short term, numerical esti-
                   mates of leaching.
                   2.     Synthetic Precipitation
                           Leaching Procedure (SPLP)
                      The SPLP is currently used by several state
                   agencies to evaluate the leaching of con-
                   stituents from wastes, and has been designat-
                   ed as EPA Method 1312 in SW-846. The
                   SPLP was designed to estimate the leachabili-
                   ty of both organic and inorganic analytes pre-
                   sent in liquids, soils, and wastes. The SPLP
                   was originally designed to assess how clean a
                   soil was in EPA's clean closure program. The
federal hazardous waste program, however,
did not adopt it for use, but the test still may
estimate releases from wastes placed in a
landfill and subject to acid rain. There may
be, however, important differences between
soil as a constituent matrix and the matrix of
a generated industrial waste. A copy of
Method 1312 has been included on the CD-
ROM for this guidance.

   The SPLP is very similar to the TCLP.
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 extraction 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 filtrate and  leachate to determine the con-
stituent concentrations.

   The sulfuric  acid/nitric acid extraction
solution used in the SPLP was selected to
simulate leachate generation, in part, from
acid rain. In both the SPLP and TCLP, oily,
and some paint wastes, may clog the filters
used to separate the extract from the solids
prior to analysis, resulting in under reporting
of the extractable constituent concentrations.


                                                                            Getting Started—Characterizing Waste
3.     Multiple  Extraction
       Procedure (MEP)
  The MEP is designed to simulate the leach-
ing that a waste will undergo from repetitive
precipitation of acid rain on a landfill to
reveal the highest concentration of each con-
stituent that is likely to leach in a real world
environment. Currently, the MEP is used in
EPA's de-listing program and has been desig-
nated as EPA Method 1320 in SW-846. A
copy of Method 1320 has been included on
the CD-ROM for this guidance.
  The MEP can be used to evaluate liquid,
solid, and multiphase samples. Waste samples
are extracted according to the Extraction
Procedure (EP)Toxicity Test (Method 1310 of
SW-846). A copy of Method 1310 has been
included on the CD-ROM for this guidance.
The EP Test is very similar to the TCLP
Method 1311. In the EP, liquid wastes are fil-
tered through a glass fiber filter. Waste sam-
ples containing solids and liquids are handled
by separating the liquids from the solid
phase, and then reducing the solids to parti-
cle size. The solids are then extracted using
an acetic acid solution. A liquid-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 liquid extract, and the
liquid extract is combined with any original
liquid fraction of the wastes. The solid por-
tions of the samples that remain after applica-
tion of Method 1310 are then re-extracted
using a dilute sulfuric acid/nitric acid solu-
tion. As in  the SPLP, this fluid was selected to
simulate leachate generation, in part, from
acid rain. This time a liquid-to-solid ratio of
20:1 by weight is used for an extraction peri-
od of 24 hours. After extraction solids are
once again filtered from the liquid extract,
and the liquid extract is combined with the
original liquid fraction of the wastes. These
four steps are repeated eight additional times.
If the concentration of any constituent of
concern increases from the 7th or Slh extrac-
tion to the 9th extraction, the procedure 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
  Shake Extraction of Solid Waste with Water,
or the Neutral Leaching Procedure, was devel-
oped by the American Society for Testing and
Materials (ASTM) to assess the leaching poten-
tial of solid waste and  has been designated as
ASTM D-3987-85.  This test method provides
for  the shaking of a water extractant and a
known weight of waste of specified composi-
tion and the separation of the aqueous phase
for  analysis. The intent of this test method is
for  the final pH of the  extract to reflect the
interaction of the extractant with the buffering
capacity 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 extract 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


Getting Started—Characterising Waste
                   and volatile organic compounds. Copies of
                   this procedure can be,ordered by calling
                   ASTM at 610 832-9585 or via the Internet at
                   III.   Waste


                          of Volatile

                          Organic Emissions
                     To determine whether volatile organic emis-
                   sions are of concern at a unit, as described in ;
                   the protecting air chapter, the concentration of
                   all volatile organics in a waste must be known.
                   Analytical testing may be necessary if organic
                   concentrations cannot be estimated using
                   process knowledge. Many tests have been
                   developed for quantitatively extracting volatile
                   and nonvolatile organic compounds from vari-
                   ous sample matrices, for example extracting all
                   of the compound present. These tests tend to
                   be highly dependent upon the physical charac-
                   teristics of the sample. ^Consult with the state
                   agency before beginning testing. Refer to SW-
                   846 Method 3500B for general guidance on
                   selection of methods for quantitative extraction
                   or dilution of samples for analysis by one of
                   the semivolatile or nonvolatile determinative .
                   methods. After performing the appropriate
                   extraction procedure, further cleanup of the
                   sample extract may be necessary if analysis of
                   the extract is prevented due to interferences
                   coextracted from the sample. Method 3600 of
                   SW-846 provides additional guidance on
                   cleanup procedures. Following preparation of
                   a sample, the sample is ready for further analy-
                   sis. Most analytical methods are either gas
                   chromatography (GC),: high performance liq-
                   uid chromatography  (HPLC), gas chromatog-
                   raphy/mass spectrometry (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 thai sample preparation, sample
cleanup, and analytical methods can be com-
bined into a sequence, as appropriate for the
particular analyte and the matrix. Consult with
the state agency before finalizing the selected


                                                                    Getting Started—Characterizing Waste
              Waste  Characterization Action  Items
Use process knowledge to identify constituents for further analysis.

Assess the physical state of the waste using process and generator knowledge.

Assess the environment in which the waste will be placed.

Consult with the state agency to determine any state specific testing requirements.

Select an appropriate leachate test or organic constituent analysis based on the above


Getting Started—Characterizing Waste
           ASTM. 1995. Annual Book of ASTM Standards. Volume 11.04.

           California EPA. Handbook for the Analysis and Classification of Wastes.

           California EPA. 1995. Preliminary Proposal to Require the TCL? 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.

           Kendall, Douglas. 1996. Impermanence of Iron Treatment of Lead-Contaminated Foundry Sand—
           NIBCO, Inc., Nacogdoches, Texas. National Enforcement Investigations Center Project PA9. April.

           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.

           New Jersey Department of Environmental Protection. 1996. Industrial Pollution Prevention Trends
           in New Jersey.

           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. 1998. Guidance on Quality Assurance Project Plans:  EPA QA/G-5. EPA600-R-98-018.

           U.S. EPA. 1997. Extraction Tests. Draft.

           U.S. EPA. 1996. Guidance for the Data Quality Assessment: Practical Methods for Data Analysis:
           EPAQA/G-9.  EPA600-R-96-084.


                                                                        Getting Started—Characterizing Waste
                                 Resources (cont.)
U.S. EPA. 1996. Guidance for the Data Quality Objectives Process: EPA QA/G-4. EPA600-R-96-055.

U.S. EPA. 1996. Hazardous Waste Characteristics Scoping Study.

U.S. EPA. 1996. National Exposure Research Laboratory (NERL)-Las Vegas: Site Characterization
Library, Volume 2.

U.S. EPA. 1996. Test Methods for Evaluating Solid Waste Physical/Chemical Methods—SW846. Third

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.



                        Part I
                    Getting Started

                      Chapter 3
Integrating Pollution Prevention, Recycling, and Treatment


I.  Benefits of Pollution Prevention, Recycling, and Treatment  3

II. Implementing Pollution Prevention, Recycling, and Treatment 4
   A. Source Reduction  5
   B. Recycling 7
   C. Treatment 7

111. Where to Find Out More: Technical and Financial Assistance     8

Action Items for Integrating Pollution Prevention, Recycling, and Treatment 11

Resources   12

  Figure 1: Waste Management Hierarchy  2


                                            Getting Started—Integrating Pollution Prevention, Recycling and Treatment
             Integrating Pollution  Prevention,
                   Recycling, and  Treatment

       Consider pollution prevention, recycling, and treatment options
       when designing a waste management system. Pollution preven-
       tion and recycling reduce waste disposal needs and can mini-
       mize impacts across all environmental media.  Treatment can
       reduce the volume and/or toxicity of waste. Pollution prevention,
       recycling, and treatment can all ease some of the burdens,
       risks, and liabilities of waste management.
         Pollution prevention, waste
         reduction, waste minimization—
         these and similar terms describe a
         variety of  practices that go far
         beyond traditional environmental
compliance or single media permits for water,
air, or waste management. This guidance is
designed to help decide how to manage
wastes protectively. Integrating pollution pre-
vention, recycling, and treatment into policies
and operations allows for opportunities to
reduce the volume and toxicity of wastes,
reduce waste disposal needs, and recycle and
reuse materials formerly handled as wastes. In
addition to the potential to save waste man-
  This chapter will help address the
  following questions:
  •  What are some of the benefits of pollu-
  tion prevention, recycling, and treatment?
  •  Where can assistance in: choosing and
  implementing specific pollution preven-
  tion, recycling, and treatment activities
  be obtained?
agement costs, pollution prevention, recy-
cling, and treatment may improve the interac-
tions among industry, the public, and regula-
tory agencies; reduce liabilities and risks asso-
ciated with releases from waste management
units; and reduce long-term liabilities and
risks associated with closure and post-closure
care of waste management units.
  Pollution prevention is comprehensive and
  emphasizes a life-cycle approach to assessing
  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
  actively involves a broad cross section of
  employees in creative problem solving to help
  achieve environmental goals and at the same
  time benefit a company in many other ways.
  For example, redesigning production process-
  es or finding alternative materials inputs can
  also improve product quality, increase effi-
  ciency, and conserve raw materials.


Getting Started—Integrating Pollution Prevention, Recycling and Treatment
                      Recycling is similar to pollution prevention
                      in the sense that both require an examina-
                      tion of waste streams and production
                      processes to identify opportunities.
                      Recycling and beneficially reusing wastes
                      can help reduce disposal costs, while using;
                      or reusing recycled materials as substitutes
                      for feedstocks can reduce raw materials'
                      costs. Materials exchange programs can
                      assist in finding uses  for recycled materials,
                      and identifying effective substitutes for raw
                      materials. Recycling >not only helps reduce :
                      the  overall amount of waste sent for dis-
                      posal, but also helps conserve natural
                      resources by replacing the need for virgin
                      Treatment can reduce the toxicity of a
                      waste, its volume, or  both. Reducing a
                      waste's volume and toxicity prior to  final
                      disposal can result in long-term cost sav-
                      ings. There are a considerable number of
                      levels and types of treatment from which
                      to choose. Selecting the right treatment
                      option can help simplify disposal options
                      and limit future liability.
   i hroughout this guidance some key steps
are highlighted thai are good starting points
for pollution prevention, recycling, or treat-
ment or where pollution prevention, recy-
cling, or treatment could 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 component
   of this guidance.  It is also a key compo-
   nent of a pollution prevention opportunity
   assessment. An opportunity assessment is
   more comprehensive, since it also covers
   material inputs, production processes,
   operating practices, and potentially other
   areas such as inventory control. When
   characterizing a waste, consider expanding
   the assessment to cover these aspects of
   the business. An opportunity assessment
   can help identify the most efficient, cost
   effective, and environmentally friendly
   combination of options, especially when
   planning new products, new or changed
   waste management practices, or facility
                                             Figure 1. Waste Management Hierarchy
                                                Waste Management Hierarchy

                                                            If NO


                                              Getting Started—Integrating Pollution Prevention, Recycling and Treatment
  Land application of waste may be a pre-
  ferred waste management option because
  land application units can manage wastes
  with high liquid content, achieve biodegra-
  dation, and improve soils with the organic
  material in the waste. Concentrations of
  constituents may 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 practice will be protective of
  human health and the environment and
  limit future liabilities.

  The Pollution Prevention Act of 1990 estab-
lished a national policy to first, prevent or
reduce waste at the point of generation; sec-
ond, recycle or reuse waste  materials; third,
treat waste; and finally, dispose of remaining
waste in an environmentally protective man-
ner (see Figure 1). Some states and many local
governments have adopted  similar policies,
often with more specific and measurable goals.
Over the past 10 years, interest in all aspects
of pollution prevention, recycling,  and treat-
ment has blossomed, and governments, busi-
nesses, academic and research institutions,
and individual citizens have dedicated greater
resources to it. Many industries are adapting
pollution prevention, recycling, and treatment
practices to fit their individual operations.
Pollution prevention, recycling, and treatment
can be successful when flexible problem-solv-
ing approaches and solutions are implement-
ed. These steps will be successful when they
fit into business and environmental goals.
I.     Benefits  of



       Recycling,  and

  Pollution prevention, recycling, and treat-
ment activities benefit industry, states, and the
public by protecting the environment and
reducing health risks, and also provide busi-
nesses with financial and strategic benefits.
  Cost savings. Many pollution prevention
activities make
industrial process-
es and equipment
more resource-effi-
cient. This
increased produc-
tion efficiency
saves raw material
and labor costs,
lowers mainte-
nance costs due to
newer equipment,
and lowers over-
sight costs due to
process simplifica-
tion. When planning pollution prevention
activities, consider the cost of the initial invest-
ment for audits, equipment, and labor. This
cost will vary depending on the size and com-
plexity of waste reduction activities. In addi-
tion, consider the payback time for the invest-
ment. Adjust pollution prevention activities to
maximize cost savings and environmental and
health benefits. Lastly, by reducing the volume
and toxicity of waste, treatment activities pro-
vide savings through lower disposal costs.
   Simpler design and operating conditions
and reduced regulatory obligations. Reducing
the risks associated with wastes may allow


Getting Started—Integrating Pollution Prevention, Recycling and Treatment '
                   wastes to be managed under less stringent
                   design and operating conditions or use of
                   other lower-cost management practices. For
                   example, the chapter on assessing ground-
                   water risks may determine that a waste stream
                   requires a composite liner. The assessment also
                   might imply that by implementing a pollution
                   prevention activity that lowered the concentra-
                   tions of one or two problematic waste con-
                   stituents in that waste stream, only a compact-
                   ed clay liner may be necessary. When the risks
                   associated with waste disposal are reduced, the
                   long-term costs of closure and post-closure
                   care may also be reduced.
                     Improved worker safety.. Processes involving
                                         less toxic and less
                                         physically dangerous
                                         (such as corrosive)
                                         materials can
                                         Improve worker safe-
                                         ty by reducing work-
                                         related injuries and
                                         illnesses. In addition
                                         to strengthening
                                         morale, improved
                                         •worker safety also
                                         reduces health-relat-
                                         ed 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 waste in some operations con-
                   sists of products that fail quality inspections,
                   so minimizing waste in those cases is inextri-
                   cably linked with process changes that
improve quality. Often, managers do not real-
ize 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 regulatory agen-
cies. If implementing a pollution 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.
II.   Implementing
       Recycling, and
  When it comes to pollution prevention,
recycling, and treatment consider a combina-
tion of options that best fits a facility and its
products. There are a number of steps com-
mon to any facility wide pollution prevention,
recycling, and treatment effort. An essential
starting point is to make a clear commitment


                                                 Getting Started—Integrating Pollution Prevention, Recycling and Treatment
to pollution prevention, recycling, and treat-
ment opportunities. Seek the participation of
interested partners, develop a policy state-
ment committing the industrial operation to
pollution prevention, recycling, and treat-
ment, and organize a team to  take responsi-
bility for it. As a next step, conduct a thor-
ough pollution prevention opportunity
assessment. Such an assessment will help set
priorities according to which options are the
most promising. Another feature common to
many pollution prevention programs is some
means of measuring the program's progress
and make any necessary adjustments.
  The core of a program is the actual pollu-
tion prevention, recycling, and treatment
practices implemented. The following sec-
tions give a brief overview of source reduc-
tion, recycling, and treatment. To find out
more, contact some of the organizations listed
in the appendices to this  chapter.

A.     Source Reduction
  Source reduction is the prevention or min-
imization of waste at the  point of generation.
Some examples of source reduction activities
are: input materials modification, technology
modifications, in-process recycling, and vari-
ous good housekeeping measures.
   Input materials modification. One option
                        is to reformulate or
                        modify products
                        and processes to
                        incorporate materi-
                        als  less likely to
                        produce higher-risk
                        wastes. Some of the
                        most common
                        practices include
                        eliminating metals
                        from inks, dyes,
                        and paints; refor-
                        mulating paints,
inks, and adhesives to eliminate synthetic
organic solvents; and replacing chemical-
based cleaning solvents with water-based or
citrus-based products. Purchasing raw materi-
als 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 processes, it is important to examine the
effect on the entire waste stream. Some
changes may 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-
tion of waste and risk reduction, altering
these existing production procedures, adopt-
ing new procedures, or upgrading equipment
may reduce waste volume, toxicity, and man-
agement costs.  Some examples include
redesigning equipment to cut losses during
batch changes or during cleaning and mainte-
nance, changing to mechanical cleaning
devices to avoid solvent use, and installing
more energy- and material-efficient equip-
ment.  State technical assistance centers, trade
associations, and other organizations listed in
Appendices I through IV can help evaluate
the potential advantages and savings of such
   In-process recycling (reuse). In-process
recycling reuses 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


Getting Started—Integrating Pollution Prevention, Recycling and Treatment
                    the need for treatment or disposal and by
                    conserving energy and resources. A common
                    example of in-process recycling is reuse of
                       Good housekeeping procedures. Some of
                    the easiest and most cost-effective waste
                    reduction techniques to implement are sim-
                    ple 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; spac-
                    ing stored materials to allow easy access; sur-
                    rounding 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.
                       Regularly scheduled maintenance and plant
                    inspections are also useful. Maintenance helps
 avoid the large cleanups and disposal opera-
 tions that can result from equipment failure.
 Routine maintenance also ensures that equip-
 ment is operating at peak efficiency, saving
 energy, time, and materials. Regularly sched-
 uled or random unscheduled plant inspections
 help identify potential problems before they
 cause waste management problems. They also
 help identify areas where improving the effi-
 ciency of materials management and handling
 practices is possible. If possible, plant inspec-
 tions occasionally should be performed by
 outside inspectors who are less familiar with
 day-to-day plant operations. These inspectors
 may notice areas for improvement that are
 overlooked by employees accustomed to the
 plant's 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. Many companies are 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 ability to
 use them, thereby decreasing disposal volume
 and cost. Furthermore, some companies have
 successfully implemented "just-in-time" man-
 ufacturing systems to  avoid the costs and
 risks associated with maintaining a large
 onsite inventory. In a  "just-in-time" manufac-
 turing system, raw materials arrive as they are
 needed and only minimal inventories are
 maintained on site.
   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 may be more efficient and cost-effec-
 tive to manage wastes separately by recycling
 some, and treating or  disposing of others.


                                                Getting Started—Integrating Pollution Prevention, Recycling and Treatment
Waste segregation can also help reduce the
risks associated with handling waste.
Separating waste streams may allow 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. If wastes from  metal-finishing facil-
ities, for example, 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 collecting, processing,
and reusing waste materials. The following
discussion highlights a few of the ways to
begin this process.
   Material exchange
programs. Many
regions and states
have established
material exchange
programs to facilitate
transactions between
waste generators and
industries that can use
wastes as raw materials. Material 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 listed with
them or to access their online databases. Some
 actively work to promote exchanges between
 generators and users, while others simply pub-
 lish lists of generators, materials, and buyers.
 Some waste exchanges also sponsor work-
 shops and conferences to discuss waste-related
 regulations and to exchange information. More
 than 60 waste and material exchanges operate
 in North America. Contact information for
some of these exchanges is provided in
Appendix III.
   Beneficial use. Beneficial use involves sub-
stituting a waste material for another materi-
al with similar properties. Utility companies,
for example, often use coal combustion ash
as a construction material, road base, or soil
stabilizer. The ash replaces other, nonrecy-
cled 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 the chapter
on designing a land application program)
and using foundry sand for 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 the
required analyses is completed. Pennsylvania,
for example, allows application of a "coprod-
uct" designation to, and exemption from
waste regulations for, "materials which are
essentially equivalent to and used in place of
an intentionally manufactured product or
produced raw material and... [which present]
no greater risk to the public or the environ-
ment." Generally, regulatory agencies want to
ensure that any beneficially used materials  are
free from significantly increased levels of con-
stituents that may pose a greater risk than the
materials they are  replacing. Consult with the
state agency for criteria and regulations gov-
erning beneficial use.

C.     Treatment
   Treating  waste helps to reduce its volume
and/or toxicity prior to disposal. Treatment
can also make a waste amenable for  reuse or
recycling. The range of treatment methods
from which to choose is as diverse as the
 •^Freeman, Harry. 1995. Industrial Pollution Prevention Handbook. McGraw-Hill, Inc. p. 13.


Getting Started—Integrating Pollution Prevention, Recycling and Treatment
                  range of wastes to be treated. More advanced
                  treatment will generally be more expensive,
                  but, by reducing the quantity and/or 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 clo-
                  sure and post-closure care costs. Conversely,
                  more basic treatment is usually less expensive
                  but may leave the final waste management
                  costs higher. Choose the treatment and post-
                  treatment waste management methods that
                  will minimize total cost and environmental
                  impact. Also, be sure to properly manage any
                  treatment residuals, such as sludges, which
                  are wastes themselves. The organizations list-
                  ed in the appendices may be able to assist in
                  identifying treatment options. '
                  III.  Where to  Find
                         Out  More:
                         and  Financial
                    There is a wealth of information available
                  to help integrate pollution prevention, recy-
                  cling, and treatment into an operation. As a
                  starting point, lists of technical and financial
                  resources that identify some of the main
                  places to turn to for assistance are included in
                  the appendices. Use the Internet as a source
                  of background information on the various
                  resources to help narrow the search for assis-
                  tance. Eventually, a network of contacts to
                  support all the various technical needs can be
                  built. Waste reduction information and tech-
                  nologies are constantly changing. To follow
                  new developments, maintain technical and
                  financial contacts and use the resources even
                  after  beginning waste reduction activities.
Where  can assistance be
   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)
Manufacturing Extension Partnerships
(MEPs) also provide waste reduction informa-
tion. Look for waste reduction staff within the
media programs (air, water, solid/hazardous
waste) of regulatory agencies or in the state
commissioner's office, special projects divi-
sion, or pollution prevention division. Some
states also provide technical assistance for
waste reduction activities, such as recycling,
through a business advocate or small business
technical assistance program.
   The listings in the accompanying appen-
dices identify some primary sources for tech-
nical assistance but are far from exhaustive.
There are many additional organizations that
offer waste reduction/pollution prevention
assistance  on regional, state, and local levels.
Some of the organizations listed by state may
be able to  help contact these other organiza-
tions. To help locate the organizations in a
state or those most relevant to an industry,
the listings are divided into four appendices.
Once started, the list of potential contacts can
be quickly expand.


                                                Getting Started—Integrating Pollution Prevention, Recycling and Treatment
•   Appendix I: State Technical
    Assistance Organizations. Regulatory
    and nonregulatory organizations
    offering various forms of technical
    assistance within each state.
•   Appendix II: Trade Associations.
    Trade associations that can give
    more industry- or material-specific
    technical assistance resources.
•   Appendix III: North American
    Material Exchange Programs. A
    sampling of material exchange pro-
    grams across North America.
•   Appendix IV: Publications, Online
    Resources, and Software. An
    overview of places to find general
    information about waste reduction
   As contact information inevitably changes
with time, check the local telephone listings
or investigate online resources, such as The
National Pollution Prevention Roundtable's
directory, The Pollution Prevention Yellow Pages
<www.p2.org/nppr_yps.html>, if trying to
contact an organization that is no longer
available at the number listed.
 What types of technical
 assistance are available?
   Many state and local governments have
 technical assistance programs that are sepa-
 rate from regulatory offices. In addition, non-
 governmental organizations implement a
 wide range of activities to educate businesses
 about the value of waste reduction. These
 efforts range from providing onsite technical
 assistance and sharing industry-specific expe-
 riences to conducting research and develop-
 ing education and outreach materials on
 waste reduction topics. The following exam-
 ples illustrate what services are available:
•   NIST technical centers. There are
    NIST-sponsored Manufacturing
    Technology Centers throughout the
    country as part of the grassroots
    Manufacturing Extension
    Partnership (MEP) program. The
    MEP program helps small and
    medium-sized  companies adopt new
    waste reduction technologies by pro-
    viding technical information, financ-
    ing, training, and other services. The
    NIST web site <www.nist.gov>
    offers a page that can help find the
    nearest center.
•   Trade associations. Trade associa-
    tions provide industry-specific
    assistance through publications,
    workshops, field research, and
    consulting services.
•   Onsite technical assistance audits.
    These audits are for small (and
    sometimes larger) businesses. The
    assessments, which take place out-
    side of the regulatory environment
    and on a strictly voluntary basis,
    provide businesses with  information
    on how to save money, increase
    efficiency, and  improve community
•   Information clearinghouses. Many
    organizations maintain repositories
    of waste reduction information and
    serve as starting points to help
    businesses access this information.
•   Facility planning assistance. A num-
    ber of organizations can help
    businesses develop,  review, or evalu-
    ate facility waste reduction plans.

   State waste reduction programs frequently
prepare model plans can implement to mini-
mize waste.


Getting Started—Integrating Pollution Prevention, Recycling and Treatment \
                        Research and collaborative projects.
                        Academic institutions, state agencies and
                        other organizations frequently participate
                        in research and collaborative projects
                        with industry to foster development  of
                        waste reduction technologies and man-
                        agement 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 informa-
                        tion to industry and the  general
                        public. Hotline staff typically answer
                        questions, provide referrals, and        :
                        distribute printed  technical materials
                        on request.
                        Computer searches and the Internet.
                        The Internet brings many
                        pollution prevention resources to a
                        users fingertips. The wide range of
                        resources available electronically can
                        provide information about inno-
                        vative 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 pro-
                        vide industry with information
                        about waste reduction. EPA and
                        many state agencies have web sites
                        dedicated to these topics, with case
                        studies, technical  explanations,
                        legal information,  and links to other
                        sites for more information.
                         Workshops, seminars, and training. State
                        agencies, trade associations, and other
                        organizations conduct workshops, semi-
                        nars, and technical training on waste
                        reduction. These events  provide informa-
                        tion, identify resources, and facilitate net
Grants and loans. A number of
states distribute funds to indepen-
dent groups that conduct waste
reduction activities. These groups
often use such support to fund
research and to run demonstration
and pilot projects.


                                           Getting Started—Integrating Pollution Prevention, Recycling and Treatment



              Action  Items for Integrating  Pollution
              Prevention, Recycling, and Treatment
Make waste management decisions by considering the priorities full range of
options—first, source reduction; second, reuse and recycling; third, treatment; last,

Explore the cost savings and other benefits available through activities that integrate
pollution prevention, recycling, and treatment.

Develop a waste reduction policy.

Conduct a pollution prevention opportunity assessment of facility processes.

Research potential pollution prevention, recycling, and treatment activities.

Consult with public and private agencies and organizations providing technical and
financial assistance for pollution prevention, recycling, and treatment activities.

Plan and implement activities that integrate pollution prevention, recycling, and


Getting Slatted—Integrating Pollution Prevention, Recycling and Treatment
           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.

           Rossiter, Alan P., ed. 1995. Waste minimization through process design. McGraw-Hill, Inc.

           U.S. EPA.  1997. Technical support document for best management practices programs—spent
           pulping liquor management, spill prevention, and control.

           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.  1993. Guidance manual  for developing best management practices.
           EPA833-B-93-004.          ;

           U.S. EPA.  1992. Facility pollution prevention guide. EPA600-R-92-008.

           U.S. EPA.  1991. Pollution prevention strategy. EPA741-R-92-001.

           U.S. EPA.  1988. Waste minimization opportunity assessment manual.

           U.S. Army Corps of Engineers, 1984. Engineering and design: Use of geotextiles under riprap. ETL

           U.S. EPA.  1995. Decision-maker's guide to solid waste management, 2nd ed. EPA530-R-95-023.
           U.S. EPA.  1995. OSWER environmental justice action agenda. EPA540-R-95-023.

           U.S. EPA.  1995. RCRA Subtitle D (258) Seismic design guidance for municipal solid waste landfill
           facilities. EPA600-R-95-051.


                                             Getting Started—Integrating Pollution Prevention, Recycling and Treatment
                                Resources  (cent.)
U.S. EPA. 1995. Why do wellhead protection? Issues and answers in protecting public drinking water
supply systems. EPA813-K-95-001.

U.S. EPA. 1994. Design, operation, and closure of municipal solid waste landfills.

U. S. EPA. 1994. Handbook: Ground water and wellhead protection.



       Part I
  Getting Started

     Chapter 4
Considering the Site


I. General Site Considerations ....;    2
   A. Hoodplains    2
   B. Wetlands  5
   C. Active Fault Areas    9
   D. Seismic Impact Zones  ,   10
   E. Unstable Areas    ,   14
   F. Airport Vicinities    17
   G. Wellhead Protection Areas 18

II. Buffer Zone Considerations  19
   A. Recommended Buffer Zones  20
   B. Additional Buffer Zones   ,   21

III. Local Land Use and Zoning Considerations   22

IV. Environmental Justice Considerations    22

Considering the Site Action  Items  24

Resources   26

Table 1: Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions  11


                                                                       Getting Started—Considering the Site
                       Considering the Site

   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 the unit an appropriate dis-
   tance from them. Comply with land use and zoning restrictions.
   Understand existing environmental justice issues when considering
   a new site. Avoid siting units in problem areas, or design units to
   address conditions in those areas.
              Many hydrologic and geologic
              settings can be effectively uti-
              lized for protective waste
              management. There are,
              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,
earthquake zones, unstable soils, and areas at
risk for subsurface movement need to be
taken into account just as they would be in
  This chapter will help address the
  Mowing questions:
  * What types of sites need special
  - How is it determined if a unit is in an
     area requiring special consideration?
  * What issues are associated with siting a.;
    . waste management unit insuch areas?
  * What actions can; be taken if a unit is
     planned to these areas?. •  y
siting and constructing a manufacturing plant
or home. Catastrophic events associated with
these locations could seriously damage or
destroy a unit, release contaminants into the
environment, and add substantial expenses
for cleanup, repair or reconstruction. If prob-
lematic site conditions cannot be avoided,
engineering design and construction tech-
niques can address some of the concerns
raised by these locations.
  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
remedy accidental releases before they reach
sensitive environments or sensitive popula-
tions. Buffer zones also help maintain good
community relations by reducing disruptions
associated with noise, traffic, and wind-blown
dust, often the source of serious neighbor-
hood concerns.
  In considering impacts on the surrounding
community, it is important to understand
whether the community, especially those with
large minority and low income populations,


Getting Started—Considering the Site
                   already face significant environmental impacts
                   from existing industrial activities. Understand a
                   community's current environmental problems
                   and work together to develop plans that can
                   improve and benefit the environment, the com-
                   munity, the state, and the company.

                   How should a unit site
                   assessment begin?
                     In considering whether to laterally expand a
                   unit or site a new unit, certain factors influence
                   prospective sites. These factors include land
                   availability, distance from waste generation
                   points, ease of access, local climatic conditions,
                   economics, environmental considerations, local
                   zoning requirements, and community impacts.
                   As prospective sites are identified, become
                   familiar with the siting concerns raised in this
                   chapter, and determine how to address them at
                   each site to minimize a unit's adverse impacts
                   on the environment and the environment's
                   adverse impacts on the unit. Choose the site
                   that best balances efficient protection of human
                   health and the environment with meeting oper-
                   ational goals. In addition to issues raised in diis
                   chapter, check widi state and local regulatory
                   agencies early in the siting process to identify
                   applicable restrictions.

                   I.  General  Siting

                     Examining  the topography of a site is die first
                   step in siting  a unit. To obtain topographic infor-
                   mation, contact the U.S. Geological Survey
                   (USGS), the Natural Resources  Conservation
                   Service (NRCS)1, the state's geological survey or
                   agency (see Appendix I), or local colleges and
                   universities. Remote sensing data or maps from
                   these organizations can help determine whether a
                   prospective site is located in any of the areas of
                   concern discussed in this section. USGS maps
can be downloaded and ordered from their web
page at <mapping.tisgs.gov>. The University of
Missouri-Rolla maintains a current list of State
Geological Surveys on their web page at
A.     Floodpiains
  A floodplain is a relatively flat, lowland area
adjoining inland and coastal waters. The 100-
year floodplain—the area susceptible to inun-
dation during a large magnitude flood with a
1 percent chance of recurring in any given
year—is usually the floodplain of concern for
waste management units. Determine whether
a candidate site is in a 100-year floodplain.
Siting a unit in a 100-year floodplain increases
the likelihood of floods inundating a surface
impoundment or land application unit,
increases the potential to damage liner and
support components of a landfill or waste
pile, and presents operational concerns. This,
in turn, creates environmental and human
health and safety concerns, as well as legal lia-
bilities.  It also can 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. Further,
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 some
parts of the Midwest.
                   •'•This agency of the U.S. Department of Agriculture was formerly known as the Soil Conservation Service (SCS).


                                                                           Getting Started—Considering the Site
FEMA provides flood maps like this one for most floodplains
Source: FEMA, Q3 Flood Data Users Guide <www.fema.gov/msc>.
locating a unit in a floodplain may exacerbate
the damaging effects of a flood, both
upstream and downstream, by reducing the
temporary water storage capacity of the
floodplain. As such, potential sites located
outside the 100-year floodplain are preferable
How is it determined if a
prospective site is in a  100-year
  The first step in determining whether a
                      prospective site is
                      located in a 100-
                      year floodplain is to
                      consult with the
                      Federal Emergency
                      Agency (FEMA).
                      FEMA has prepared
                      temporary flood
                      hazard boundary
                      maps for most
                      regions. If a
                      prospective site
                      does not appear to
                      be located in a
                      floodplain, future
                      exploration is not
                      necessary. If uncer-
                      tainty exists as to
                      whether the
                      prospective site may
                      be in a floodplain,
                      several sources of
                      information are
                      available to help
                      make this determi-
                      nation. More
                      detailed flood insur-
                      ance rate maps
                      (FIRMs) can be
                      obtained from
                      FEMA that classify
areas into three classes: A, B, and C. Class A
zones are the most susceptible to flooding
while Class C zones are the least susceptible.
FIRMs may be obtained from FEMA's web
page at <www.fema.gov/tnsc/hardcoiysr.litin>.
  Additional information can be found on
flood insurance rate maps in FEMA's publica-
tion How to Read a Flood Insurance Rate Map
(see <www.fema.gov/NFIP/readmap.htm>).
FEMA also publishes The National Flood
Insurance Program Community Status Book,
which lists communities with flood insurance
rate maps or floodway maps. Floodplain maps


Getting Started—Considering the Site
                    can also be obtained through the U.S. Army
                    Corps of Engineers (COE); USGS; NRCS; the
                    Bureau  of Land Management; the Tennessee
                    Valley Authority; and state, local, and tribal   .
                      Note that river channels shown in flood-
                    plain maps may have changed due to
                    hydropower or flood control projects. As a
                    result, some floodplain boundaries may be
                    inaccurate. If this is suspected to be the case,
                    consult recent aerial photographs to determine
                    how river channels have been modified.
                      If maps can not be located, and a potential
                    site is suspected to be located in a floodplain,
                    conduct a field study to delineate the floodplain
                    and determine die floodplain's properties. A
                    delineation can draw on meteorological records
                    and physiographic information, such as existing
                    and planned watershed land use, topography,
                    soils and geographic mapping, and aerial photo-
                    graphic interpretation of land forms.
                    Additionally, use the U.S. Water Resource
                    Council's methods of determining flood poten-
                    tial based on stream gauge records, or estimate
                    the peak discharge to approximate the probabili-
                    ty of exceeding die 100-year flood.
                    What can  be done if a prospec-
                    tive site is in a floodplain?
                     If siting a waste management unit in a flood-
                    plain, design die unit to prevent the washout
                    of waste, avoid significant alteration of flood
                    flow, and maintain die temporary storage
                    capacity of the floodplain. Use engineering
                    models to estimate a floodplain's storage
                    capacity and floodwater flow velocity. The
                    COE Hydrologic Engineering Center has
                    developed several computer models for simu-
                    lating flood properties.3 The models can
                    account for a waste management unit placed
                    in a floodplain and can also simulate flood
                    control structures and sediment transport. If a
                                              computer model calculates that placement of
                                              the waste management unit in the floodplain
                                              raises the base flood level by more than 1 foot,
                                              the unit may alter the storage capacity of the
                                              floodplain. If designing a new unit, site it to
                                              minimize these effects. The impact of a unit's
                                              location on the speed and flow of flood waters
                                              determines die likelihood of waste washout.
                                              To quantify this, estimate the shear stress on
                                              the unit's components caused by the imping-
                                              ing flood waters at the depth, velocity, and
                                              duration associated with the peak, or highest,
                                              flow period of the flood.
                                                Several available options can protect a waste
                                              management unit from flood damage and
                                              •  Design embankments using materi-
                                                  als such as riprap—rock cover used
                                              Knowing the behavior of waters at their
                                              peak flood level is important for determin-
                                              ing whether waste will wash out.
                   ^Copies of flood maps from FEMA are available at Map Service Center, P.O. Box 1038, Jessup, MD
                   20794-1038, or by phone 800 358-9616 or the Internet at <www.femi.gov/nfip/readmap.htm>.
     HEC-1, HEC-2, HEC-5, and HEC-6 software packages are available free of charge through the COE
World Wide Web site, <www.wrcrhec.usace.army.mil/software/software.htm]>.


                                                                              Getting Started—Considering the Site
       to protect soil in dikes or channels
       from erosion—and/or geotextiles to
       minimize erosion.
•   Construct dikes to serve as barrier
    walls to protect the disposal area.
    This is especially important in the
    case of surface impoundments.
•   Consider erosion control methods,
    such as gabions—structures formed
    from crushed rock encased in wire
    mesh—or paving bricks and mats
    constructed of natural or geosyn-
    thetic materials. These materials can
    provide erosion protection and allow
    for vegetative growth.
   While these methods may help protect a
unit from flood damage and washout, be
aware that they may further contribute to
decreasing the water storage and flow capaci-
ty of the floodplain. This, in turn, may raise
the level of flood waters not only in the 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 not siting a waste management unit in a
 100-year floodplain.
 B.     Wetlands
   Wetlands, which include swamps, marshes,
 and bogs, are vital and delicate ecosystems.
 They are among the most productive biological
 communities on earth and provide habitat for
 many plants and animals, including approxi-
 mately 45 percent of all endangered or threat-
 ened species. Wetlands protect water quality by
 assimilating water pollutants, removing sedi-
 ments containing 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 recre-
ational opportunities.

   Potential adverse impacts associated widi
locating a unit in a wetland include dewatering
the wetland, contaminating the wetland, and
causing loss of wetland acreage. Damage also
could be done to important wetland ecosys-
tems by destroying their aesthetic qualities and
diminishing wildlife breeding and feeding
opportunities. Siting in a wetland also increases
the potential for damage to a unit, especially
the liner system and structural components, as
a result of ground settlement, action of the high
water table, and flooding. Alternatives to siting
a waste management unit in a wedand should
be given serious consideration based upon
Section 404 requirements in the Clean Water
Act (CWA) discussed below.
    If a unit is to be sited in a wedand, die
unit will be subject to additional regulations.
In particular, CWA Section 404 authorizes
the Secretary of the Army, acting through the
Chief of Engineers (COE), to issue permits
for the discharge of dredged or fill material
into wetlands and other waters of the United
States.4 Activities in waters  of the United
States regulated under this  program include
fills for development, water resource projects,
infrastructure improvements, and conversion
of wetlands to uplands for farming and
forestry. Section 404 stipulates that no
discharge of dredged or fill material can be
   For regulatory^pufposes under the
   Water Act,swetlattds are defined as areas'
   "that are inundg:ed^or saturated,by,sur-  „
   face or ground water at a frequency arid'%
   duration, sufficient to support^andjthat
   under normal orcumstances'do 'support,
   a prevalence of vegetation- typically adapt-
   ed for life in saturated" sofl conditions." '
   /         y    *•       S~~
  ;40 Code of Federal Regulations
   (CFR)232.2(r)~   *  ,   -
  33 United States Code 1344.


Getting Started—Considering the Site
                    Riprap reduces stream channel erosion (left) and gabions help stabilize erodible slopes
                    Sources: U.S. Department of the Interior, Office of Surface Mining (left); The Construction Site—A Directory To
                    The Construction Industry, <www.constr.com> (right).
                    permitted if a practicable alternative exists
                    that is less damaging to the aquatic environ-
                    ment or if the nation's waters would be sig-
                    nificantly degraded.  Therefore, in compliance
                    with the guidelines established under Section
                    404, all permit applicants must:
                    •   Take steps to avoid wedand impacts
                        where practicable;
                    •   Minimize impacts to wetlands where
                        they are unavoidable; and
                    •   Compensate (offset) for any remaining,
                        unavoidable impacts by restoring
                        existing wetlands;or creating new wet-
                        EPA and COE joindy administer a review
                    process to issue permits for regulated activities.
                    For projects with potentially significant
                    impacts, an individual permit is usually
                    required. For most discharges with only mini-
                    mal adverse effects, COE may allow applicants
                    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 numerous other federal laws that
may restrict placement of waste management
units in wetlands. These include the
Endangered Species Act, die 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 known  if a  prospective
site  is  in a wetland?
    As a first step, determine if the prospec-
tive site meets the definition of a wetland. If
the prospective site does not appear to be a
wetland then no further exploration is neces-
sary. If it is uncertain whether the prospective
site is a wetland, then several sources are
available to help make this determination and
define the boundaries of the wetland.
Although this can be a challenging process, it
will help avoid future liability since filling a
wetland without the appropriate federal, state,
or local permit is a violation of the law. It may
be possible to leam the  extent of wetlands


                                                                               Getting Started"—Considering the Site
Spruce bog (left) and Eco Pond in the Florida Everglades (right): different types of wetlands.
without performing a new delineation, since
many wetlands have previously been mapped.
The first step, therefore, should be to deter-
mine whether wetland information is available
for the area. At the federal level, four agencies
are principally involved with wetlands identi-
fication and delineation: COE, EPA, the U.S.
Fish and Wildlife Service (FWS), and NRCS.
EPA also has a Wetlands Protection Hotline
(800 832-7828) and a wetlands web page at
<www.epa.gov/owow/wetlands> which pro-
vides information about EPA's wetlands pro-
gram; facts about wetlands; the laws, regula-
tions, and guidance affecting wetlands; and
science, education, and information resources
for wetlands. The local offices of NRCS (in
agricultural areas) or COE (see Appendix II
for contact information) may know whether
wetlands in the vicinity of the potential site
have already been delineated. Additionally,
FWS maintains the National Wetlands
Inventory (NWI) Program5, from which wet-
lands mapping for much  of the United States
is obtainable. This mapping, however, is
based on aerial photography, which is not reli-
able for specific field determinations. If a site
has recently been purchased, the previous
property owner may know whether any delin-
eation has been completed that may not be on
file with these agencies. Even if existing delin-
eation information for the site is found, it still
may be prudent to contact a qualified wet-
lands consultant to verify the wetland bound-
aries, especially if the delineation is not a field
determination or is more than a few years old.
   If the existence of a wetland is uncertain,
obtain a wetlands delineation. This procedure
should be performed only by a qualified pro-
fessional wedands delineator6 using standard
federal delineation procedures or applicable
state or local delineation standards. The delin-
eation procedure, with which to become famil-
iar with before hiring a delineator, involves col-
lecting maps, aerial photographs, plant data,
soil surveys, stream gauge data, land use data,
and other information. Delineation for Section
404 permitting purposes should be conducted
in accordance with the 1987 U.S. Army Corps
of Engineers Wetlands Delineation Manual.7
(HQUACE, 27 Aug. 91). The manual provides
guidelines and methods to determine whether
an area is a wetland for purposes of Section
 5To contact NWI, write to National Wetlands Inventory, 9720 Executive Center Drive, Suite 101, Monroe
 Building, St. Petersburg, FL 33702; or call 813 570-5412; or fax 813 570-5420. For additional informa-
 tion online or to search for maps of an area, connect to <www.nwi.fws.gov>.

 6In March 1995, COE proposed standards for a Wetlands Delineator Certification Program (WDCP).
 Until these standards are finalized, there is no federal certification program.  Once the WDCP standards
 are implemented, use WDCP-certified wetland consultants.

 ^The 1987 manual can be obtained from NTIS (see References section below) or online at


Getting Started^-Considering the Site
                     Wetland Resource Map
                      Tampa Bay, Florida

                      • JtoiK rad EttMriM DKprate Hah&fe
                      Q Beepnater Ltlw aid Stan
                      • ErtuBK R&nfes aid Aqratic Bede
                         Slimline Fire fed Weflmdi
                         HajdMrolw nti Aqtalic Beds

                         felalrhe Snl&rib
                      — H&jor Road*
                    NWI wetland resource maps like this one show the locations of various different types of wet-
                    lands and are available for many areas.
                    Source: NWI web site, sample GIS Think Tank maps page, <www.nwi.fws.gov/maps_tank.html>.
                   404. The manual outlines a three-parameter
                   approach that determines the presence and
                   location of hydrophytic vegetation, wetland
                   hydrology, and hydric soils.
                   What can be done  if a  prospec-
                   tive site is in a wetland?
                      Before building a waste management unit
                   in a wetland area, consider whether the unit
                   can be located elsewhere. If an alternative
                   location can be identified, strongly consider
                   pursuing such an option. Section 404 of the
                   CWA requires this.  As wetlands are important
                   ecosystems that should be protected, identify-
                   ing practicable alternatives to locating a unit
                   in a wetland area is a necessary step in the
siting process. Even if no viable alternative
locations are identified, it may be beneficial
to keep a record of investigated alternatives,
noting why they were not acceptable. Such
records may be useful during the interaction
between industries, states, and members of
the community.
   If no alternatives are available, consult
with state and local governments about wet-
land permits. Most states operate permitting
programs under the CWA, and state authori-
ties can help navigate the permitting process.
To obtain a permit, the state might require an
operator to assess wetland impacts and then:
•   Prevent contamination from leachate
    and run-off;
•   Minimize dewatering effects;


                                                                               Getting Started—Considering the Site
•   Compensate the loss of wetland
    acreage by creating new wetlands or
    restoring existing ones; and
•   Protect the waste management unit
    against settling.

C.     Active  Fault Areas
   Faults occur when stresses in a geologic
material exceed its ability to withstand them.
Areas surrounding faults are subject to earth-
quakes and ground failures, such as landslides
or soil liquefaction. Fault movement may
weaken or destroy structures directly, or seis-
mic activity associated with faulting may cause
damage to structures dirough vibrations. Any
damage to the waste management unit could
result in the release of contaminants. In addi-
tion, 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 granular
material turns into a viscous fluid, a process
referred to as liquefaction. This diminishes the
bearing capacity of the soils and may 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, design the
unit to withstand the potential ground move-
ment associated with the fault area. A fault is
considered active if there has been movement
along the fault within the last 10,000 to
 12,000 years.
How is it  known 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.8 These maps may
not be completely accurate due to recent
shifts in fault lines. If a prospective site is well
outside the 200 foot area of concern, no fault
area considerations would exist. If it is
unclear how close a prospective site is to an
active fault, more evaluation will be neces-
sary. A geologic reconnaissance of the site
and surrounding areas may be useful in veri-
fying that the site is free of active faults.
    If a prospective site is in an area known
or suspected  to be prone to faulting, conduct
a fault characterization to determine if the site
is near a fault. A characterization includes
identifying linear features that suggest the
presence of faults within a 3,000-foot radius
of the site. Such features might be shown or
described on maps, aerial photographs,9 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, con-
duct further investigation to determine
whether any  of the faults are active within
200 feet of the unit.  This investigation may
involve drilling and trenching the subsurface
to locate fault zones  and evidence of faulting.
Use perpendicular trenching on any fault
within 200 feet of the proposed unit to exam-
ine the seismic epicenter for indications of
recent movement.
Information about ordering these maps is available by calling 800 USA-MAPS or 303 236-7477.

9The National Aerial Photographic Program and the National High Altitude Program, both administered
by USGS, are good national sources of aerial photographs for prospective sites. To order from USGS, call
605 594-6151. For more information, visit <www.mapping.tisgs.gov/esic/aphowto.htm]>. Local aerial
photography firms and surveyors are also good sources.


Getting Started—Considering the Site
                   What can be done if a  prospec-
                   tive 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
                   activity, there are two issues to consider: hori-
                   zontal accelerations and movements affecting
                   side slopes. Horizontal acceleration becomes
                   a concern when a location analysis reveals
                   that the site is in a zone of increased 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 incorpo-
                   rate measures to protect the unit from poten-
                   tial ground shifts. To address side slope con-
                   cerns, conduct a seismic stability analysis to
                   determine the most effective materials and
                   gradients for protecting the unit's slopes from
                   any seismic instabilities. Further, design the
                   unit to withstand the impact of vertical accel-
                     If an investigation reveals that a unit is in
                   an area susceptible to liquefaction, consider
                   ground improvement measures.  These mea-
                   sures include grouting, dewatering, heavy
                   tamping, and/or excavation. See Table 1 for
                   examples of currently available techniques.
                        Further engineering options for fault
                   areas include the use of flexible pipes for run-
                   off and leachate collection and redundant
                   containment systems. In the event of founda-
                   tion soil collapse or heavy shifting, flexible
                   run-off and leachate collection pipes—along
In this aerial view, the best-known fault in the
U.S., the San Andreas, slices through the
Carrizo Plain east of San Luis Obispo, California.
Source: USGS

 with a bedding of gravel or permeable materi-
 al—can absorb some of the shifting-related
 stress to which the pipes may be subjected.
 Consider also a secondary containment mea-
 sure, such as an additional liner system. In
 earthquake-like conditions, a redundancy of
 this nature may be necessary to prevent cont-
 amination of the surrounding area if the pri-
 mary liner system fails.
 D.    Seismic  Impact Zones
     A seismic impact zone is an area having a
 10 percent or greater probability that the
 maximum horizontal acceleration caused by
 an earthquake at the site will exceed 0.1 g in
 250 years. This seismic activity may damage


                                                                                    Getting Started—Considering the Site
                                               Table 1
           Examples of Improvement Techniques for Liquefiable Soil Foundation Conditions
Method Principle Most Suitable Soil Applications 1
Conditions/Types 1
Displacement and
compaction grout
piles and walls
Heavy tamping
Shock waves and vibrations
cause limited liquefaction,
displacement, remolding, and
settlement 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 intro-
duced 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;
All soils.
Sand, silts, clays, all soft or
loose inorganic soils.
Cohesionless soils best,
other types can also be
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 densities to nonliquefi-
able condition. The dense col-
umn of backfill provides (a) vert-
ical support, (b) drainage to
relieve pore water pressure, and
(c) shear resistance in horizontal
and inclined directions. Used to
stabilize slopes and strengthen
potential failure surfaces.
Useful in soils widi fines. Increases
relative densities to nonliquefiable
range. Provides shear resistance in
horizontal and inclined directions.
Useful 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 poten-
tial 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 liquefac-
tion 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. EPA600-R-95-051


Getting Started—Considering the Site
                    leachate collection, detection, and removal
                    systems or other unit structures through
                    excessive bending, shearing, tension, and/or
                    compression. If a unit's components fail,
                    leachate may contaminate surrounding areas.
                    For safety reasons, therefore, it is recommend
                    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 failures, soil compaction,
                    ground subsidence,  and soil liquefaction.
                      Additionally, if a unit is built in a seismic
                    impact zone, avoid rock and soil types that are
                    especially vulnerable to earthquake shocks.
                    These include very steep slopes of weak, frac-
                    tured, and brittle rock or unsaturated loess,
                    which are vulnerable to transient shocks
                    caused by tensional faulting. Avoid loess and
                    saturated sand as well, because seismic shocks
                    can liquefy them, causing sudden collapse  of
                    structures. Similar effects are possible in sensi-
                    tive cohesive soils when natural moisture
                    exceeds the soil's liquid limit. (See the "Soil
                    Properties" section in ;the chapter on designing
                    and installing liners for a discussion of liquid
                    limits.) Earthquake-induced ground vibrations
                    can also compact loose granular soils. This
                    could result in large uniform or differential set-
                    dements of the ground surface.
                    How is  it known 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 may be unnecessary. If it
                    is unclear whether the area has a history of
                    seismic 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 Maps for
                                              the United States and Puerto Rico.10 It provides
                                              state- and county-specific information about
                                              seismic impact zones. Additional information
                                              is available from the USGS National
                                              Earthquake Information Center (NEIC),11
                                              which maintains a database of known earth-
                                              quake and fault zones.
                                                 If a site is or may be in a seismic impact
                                              zone, it also is useful to analyze the effects of
                                              seismic activity on soils in and under a unit.
                                              Computer software programs are available
                                              that can evaluate soil liquefaction potential.
                                              Liquefaction is the process by which soils
                                              change from solid to liquid state due to
                                              repeated shearing during or following an
                                              earthquake. LIQUFAC, 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 dimension-
                                              al settlements 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
                                              components of the unit—including liners,
                                              leachate collection systems, and surface-water
                                              control systems—should be designed to resist
                                              the earthquake-related stresses expected in the
                                              local soil. Consult professionals experienced
                                              in seismic analysis and design to ensure that
                                              the unit is designed appropriately. To deter-
                                              mine 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 com-
                                              paction, sorting (organization of the soil
                          information on ordering these maps, call 800 HELP-MAP; or write: USGS Information Services,
                    Box 25286, Denver, CO 80225; or fax 303 202-4693. On-line information is available at
     contact NEIC, call 303 273-8500; or write: United States Geological Survey, National Earthquake
Information Center, Box 25046, DFC, MS 967, Denver, Colorado 80225; or fax 303 273-8450; or e-mail
sedas@gldfs.cr.usgs.gov. For on-line information, see <www.neic.cr.usgs.gov>.


                                                                              Getting Started—Considering the Site
              Peak Acceleration (%g) with 10% Probability of Exceedance in 50 Years
                              site: NEHRP B-C boundary                  $
                                U.S. Geological Survey
                         National Seismic Hazard Mapping Project
USGS seismic impact maps like this one show the likelihood of occurance of an seismic event with
a specified peak acceleration.
Source: USGS National Earthquake Information Center <www.neic.cr.usgs.gov>.
particles), and saturation, as well as peak
acceleration of the potential earthquake.
  After an evaluation of soil behavior, choose
appropriate earthquake protection-measures.
These might include shallower slopes, dike
and run-off control designs using conserva-
tive safety factors, and contingency plans or
backup systems for leachate collection should
the primary systems be disrupted. Unit com-
ponents should be able to withstand the
additional forces imposed by an earthquake
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 and 0.20 g). Embankments
made of insensitive, cohesive soils founded
on cohesive soils or rock may withstand even
greater seismic shocks. For earthen embank-
ments in seismic regions, consider designs
with internal drainage and core materials
resistant to fracturing. Prior to or during unit
construction in a seismic impact zone,
evaluate excavation slope stability to deter-
mine the appropriate grade  of slopes to mini-
mize potential slip.
   For landfills and waste piles, use shallower
waste side slopes, as steep slopes are more
vulnerable to  slides and collapse during
earthquakes. Use fill sequencing techniques
that avoid concentrating waste in one area of
the unit for an extended period of time. This


Getting Startedr—Considering the Site
                    prevents waste side slopes from becoming
                    too steep and unstable and alleviates differen-
                    tial loading of the foundation components.
                    Placing too much waste in one area of the
                    unit may lead to catastrophic shifting during
                    an earthquake or heavy seismic activity.
                    Shifting of this nature may 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, employ the soil improvement meth-
                    ods described in Table 1. Treating liquefiable
                    soils in the vicinity of the unit will improve
                    foundation stability and help prevent uneven
                    settling or possible collapse of heavily satu-
                    rated soils underneath or near the unit.
                       To protect against earthquake-related stress-
                    es, consider redundant liners  and special
                    leachate collection and removal system com-
                    ponents, such as secondary liner systems,
                    composite liners, and leak detection systems
                    combined widi a low permeability soil layer.
                    These measures function as backups to the
                    primary containment and collection systems
                    and provide a greater margin  of safety for
                    units during possible seismic  stresses.
                    Examples  of special leachate systems include
                    high-strength, flexible materials for leachate
                    containment systems; geomembrane liner sys-
                    tems underlying leachate containment sys-
                    tems; and perforated polyvinyl chloride or
                    high-density polyethylene piping in a bed of
                    gravel or other permeable material.

                       E.   Unstable Areas
                       Unstable areas are locations susceptible to
                    naturally occurring or human-induced events
                    or forces capable of impairing the integrity of
                    a waste management unit. Naturally occur-
                    ring unstable areas include regions with poor
soil foundations, regions susceptible to mass
movement, or regions containing karst ter-
rain, which may include hidden sinkholes.
Unstable areas caused by human activity may
include areas near cut or fill slopes, areas
with excessive drawdown of ground water,
and areas where significant quantities of oil
or natural gas have been extracted. Siting in
an unstable area may make monitoring a site
or performing remediation,' if necessary,
impossible to do. Siting in an unstable area
should be avoided. If necessary, technical and
construction techniques should be consid-
ered to mitigate against potential damage.
   The three primary types of failure diat can
occur in an unstable area are settlement, loss of
bearing strength, and sinkhole collapse.
Settlement can result from soil compression if a
unit is, or will be, located in an unstable area
over a thick, extensive clay layer. The unit's
weight may force water from the compressible
clay, compacting it and allowing the unit to  set-
tle. Settlement may increase as waste volume
increases and may 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 elon-
gation 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.
Engineer a unit to minimize the impacts of set-
tlement if it 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 may increase 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,


                                                                              Getting Started—Considering the Site
Sinkholes, like this one that occurred just north of Orlando, Florida in 1981, are a risk of
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.
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 known if a  prospective
site is  in  an unstable area?
   Before designing a waste management unit
on a prospective site whose stability has not
previously been assessed, a stability assessment
study should be conducted by a qualified pro-
fessional. The qualified professional should
assess natural conditions, such as soil geology
and geomorphology, as well as both surface
and subsurface human-induced features or
events that could cause differential ground set-
tlement. Naturally unstable conditions 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 may include
the following steps:
   Screen for expansive soils. Such soils may
   lose their ability to support a foundation
   when subjected to certain natural events,
   such as heavy rain, or human-made
   events, such as explosions. Expansive soils
   usually are clay-rich and, because of their
   molecular structure, tend to swell and
   shrink by taking up and releasing water.
   Such soils include smectite (montmoril-
   lonite  group) and vermiculite days. In
   addition, soils rich in white alkali (sodium
   sulfate), anhydrite (calcium  sulfate), or
   pyrite (iron sulfide) also may swell as
   water  content increases. These soils are
   more common in the arid western states.
   Check for soil subsidence. Soils subject to
   rapid subsidence include loesses, unconsoli-
   dated  clays, and wetland soils. Loess is a
   wind-deposited, moisture-deficient silt that
   tends  to compact when wet.  Unconsolidated
   days can undergo considerable compaction
   when oil or water is removed. Similarly, wet-
   land soils, which by their nature are water-
   bearing, are also subject to subsidence when
   water is withdrawn.


Getting Started—Considering the Site
                    Subsidence, slippage,
                    and other kinds of slope
                    failure can damage  ;
                           Look for areas
                           subject to mass
                           movement or
                           slippage. Such.
                           areas are often
                           situated on
                           slopes and tend
                           to have rock or
                           soil conditions
                           conducive to
                           downhill sliding.
                           Examples of
                           mass movements
                           avalanches, land-
                           slides, and rock
                           slides. Some sites
                           may require cut-
                           ting or rilling
                           slopes during
   construction. Such activities may cause
   existing soil or rock to slip.
   Search for karst terrain. Karst features are
   areas containing soluble bedrock, such as
   limestone or dolomite, that has been dis- \
   solved and eroded by water, leaving char-
   acteristic physiographic features including
   sinkholes, sinking streams, caves, large
   springs, and blind valleys. These areas are
   subject to extreme incidents of differential
   settlement, including complete ground
   collapse.  Karst features also can hamper
   detection and control of leachate, which
   can move rapidly through hidden conduits
   beneath the unit.  Karst maps, such as
   Engineering Aspects of Karst, Scale
   1:7,500,000, Map No. 38077-AW-NA-
   07M-00,  produced by the USGS12 and
   state specific geological maps can be
   reviewed to identify karst areas.
   Scan for evidence of excessive drawdown
   or oil and gas extraction.  Removing under-
   ground water can increase the effective
   overburden on the foundation soils under-
   neath the unit. Excessive drawdown 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
   consultant can accomplish this by per-
   forming standard penetration tests, field
   vane shear tests, and laboratory tests. This
   information will determine how large a
   unit can be placed safely on the site. Other
   soil properties to examine include water
   content, shear strength, plasticity, and
   grain size distribution.
   Examine the liquefaction potential The liq-
   uefaction potential of embankments, slopes,
   and foundation soils must be determined.
   Highly liquefiable soils are less conducive to
   safe operation of a waste management unit.
   Consult Section C above for more informa-
   tion about liquefiable soils.

What can  be done if  a prospec-
tive site  is in  an  unstable area?
   It is advisable not to locate or expand a
waste management unit in an unstable area.
If a unit is, or will be located in such an area,
safeguard the structural integrity of the unit
by incorporating appropriate measures into
the design. If this is not done, the integrity of
the unit may be jeopardized. For example, to
safeguard the structural integrity of side
slopes in an unstable area, reduce slope
height, flatten slope angle, excavate a bench
in the upper portion of the slope, or buttress
slopes with compacted earth or rock fill.
Alternatively, build retaining structures, such
as retaining walls  or slabs and piles. Other
approaches include geotextiles and geogrids
to provide additional strength, wick and toe
      information on ordering this map, call 800 USA-MAPS; or write: USGS Information Services, Box
25286, Denver, CO 80225; or fax 303 202-4693; On-line information is available at


                                                                              Getting Started—Considering the Site
drains to relieve excess pore pressures, grout-
ing, and vacuum and wellpoint pumping to
lower ground-water levels. In addition, sur-
face drainage may 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 pres-
ence of sinkholes, solution cavities, and sub-
terranean caverns. The unpredictable and
sometimes catastrophic nature  of subsidence
in these areas makes them difficult and
expensive to develop. 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.  Use more than
one technique to confirm and correlate find-
ings and anomalies, and have a qualified geo-
physicist interpret the results of these explo-
   Remote sensing techniques, such as aerial
photograph interpretation,  can provide addi-
tional information on karst terrains. Surface
mapping can help provide an understanding
of structural patterns and relationships in
karst terrains. An understanding of local car-
bonate geology and stratigraphy can help
with the interpretation of both remote sens-
ing and geophysical data.
   Incorporate adequate engineering controls
into any waste management unit located in
karst terrain. In areas where karst development
is minor, loose soils overlying the limestone
may be excavated or heavily compacted to
achieve the needed stability Similarly, in areas
where the karst voids are relatively small, the
voids may be filled with slurry cement grout
or other material.
   Engineering solutions can try to compen-
sate for the weak geologic structures by pro-
viding ground supports. For example, ground
modifications, 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 may not always prevent the
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 construc-
tion 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,  be aware
of issues that take on added importance in
such areas and become familiar with Federal
Aviation Administration (FAA) regulations
and guidelines. The chief concern associated
with waste management units near airports is
the hazard posed to aircraft by birds, which
often feed at units managing putrescible
waste. Planes can lose propulsion when birds
are sucked into jet engines, and may sustain
other damage in collisions with birds.
Another area of concern for landfills and
waste piles near airports is the height of the
accumulated waste. In such situations, exer-
cise caution when managing waste in units
that are significantly above ground level.
 Industrial waste management units that do


Getting Started—Considering the Site
                   not receive putrescible wastes should not
                   have a problem with birds.

                   How is it known if a prospective
                   site  is  in an airport vicinity?
                      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 airports,
                   obtain local maps of the area using the
                   Internet or from the state and identify any
                   nearby public use airports. Topographic
                   maps available from USGS also provide a
                   suitable basis for determining airport loca-
                   tions. If necessary, FAA can provide informa-
                   tion on the location of all public-use airports.
                   In accordance 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 runway, the affected airport and the
                   regional FAA office should be notified to pro-
                   vide them an opportunity for review and

                   What can be done if a prospec-
                   tive site is in an airport vicinity?
                      If a unit is, or will 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
                   the-unit so it does not pose a bird hazard to
                   aircraft and,  for above-ground units, does not
                   interfere with flight patterns. If it appears
                   that height may be a concern, consider
                   entrenching the unit or choosing a site out-:
                   side the airport's flight patterns. The types of
                   waste handled at most nonhazardous indus-
                   trial units do not usually include attractive
                   food sources for birds, but if a unit handles
                   waste that may potentially attract birds, pre-
                   cautions should be taken to prevent birds
                   from becoming an aircraft hazard. Discourage
congregation of birds near a unit by prevent-
ing water from collecting on site; eliminating
or covering wastes that might serve as a food
source; constructing physical barriers, such
as a canopy of fine wires or nets strung
around the disposal and storage areas; using
visual deterrents, including realistic models
of the expected scavenger birds' natural
predators; employing sound deterrents, such
as cannon sounds, distress calls of scavenger
birds, or the sounds of the birds' natural
predators; or removing nesting and roosting
areas (unless such removal is prohibited by
the Endangered Species Act).

G.    Wellhead Protection
   Wellhead protection involves sheltering
the ground-water resources that supply pub-
lic drinking water systems. A wellhead pro-
tection area (WHPA) is the area most suscep-
tible to contamination surrounding a well-
head.  WHPAs are designated and often regu-
lated to prevent public drinking water
sources from becoming contaminated. The
technical definition,  delineation, and regula-
tion of WHPAs vary from state to state.
Contact the state environmental agency to
determine what wellhead protection mea-
sures are in place near prospective sites.
Section II  of this chapter provides examples
of how some states specify minimum allow-
able distances between waste management
units and public water supplies, as well as
drinking water wells. Locating a waste man-
agement unit in a WHPA can create a poten-
tial avenue for drinking water contamination
through accidental release of leachate, conta-
minated run-off, or waste.


                                                                          Getting Started—Considering the Site
How is it known if a  prospective
site is in  a wellhead protection
  If the prospective site is not located near a
WHPA, further evaluation is not necessary. If
there is uncertainty regarding the proximity of
the prospective site to a WHPA, contact the
state environmental agency. A list of state well-
head protection program contacts is available
on EPA's web page at
and is included in Appendix III. Also, USGS
and NRCS both can provide maps that help in
delineating WHPAs. For further expertise,
contact local water authorities, or universities.

What can be  done  if a prospec-
tive site is in a wellhead
protection area?
  If a new unit or lateral expansion will be
located in a WHPA or suspected WHPA, con-
sider design modifications to help prevent
any ground-water contamination. 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
water that has percolated through the waste,
from reaching the  ground water and possibly
affecting the public drinking water source.
  In addition to ground-water barriers, con-
sider using leachate collection, leak detection,
and run-off control systems. Leachate conta-
mination is possibly the greatest threat to a
public ground-water supply posed by a waste
management unit. Incorporating leachate col-
lection, leak detection, and run-off control
systems should further minimize leachate
from escaping into the ground water.

  Control systems that separate storm-water
run-on from any water that has contacted
waste should also be provided. Proper control
measures that redirect storm water to the
supply source area should help alleviate this
II.   Buffer  Zone

  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 in
the  surrounding areas. Consult with state reg-
ulatory agencies and local advisory boards
about buffer zones before constructing a new
unit or expanding an existing unit.
  Buffer zones provide time and space to
mitigate situations where accidental releases
may cause adverse human health or environ-
mental impacts. These zones provide four
primary benefits: maintenance of quality of
the  surrounding ground water, prevention of
contaminant migration off site, protection of
drinking water supplies, and minimization of
nuisance conditions perceived in surrounding
areas. The size of the buffer zone will be
directly related to the intended benefit.
    Protecting ground water should be the
primary concern for all involved parties.
Ensure that materials processed and disposed
of at a unit are isolated from ground-water
resources. Placing a unit further from the
water table, and increasing the number of
physical barriers between the unit and the


Getting Started—Considering the Site
                    Many nearby areas and land uses, such as
                    schools, call for consideration of buffer zones.

                    water table, improves ground-water protec-
                    tion. It is therefore advised that in addition to
                    incorporating a liner system into a waste
                    management unit's design, a site where an
                    adequate distance separates the bottom of a
                    unit from the water table should be selected
                    (see Appendix IV: State Buffer Zone
                    Considerations: Table 5 for a summary of the
                    most common minimum separation distances
                    between the bottom of a waste management
                    unit and the water table).  In the event of a
                    release, dais separation distance will allow for
                    dilution and natural attenuation to protect
                    ground water.13
                      Additionally, in die event of an unplanned
                    release, an adequate buffer zone will allow
                    time for remediation activities to control con-
                    taminants before they spread off site. It also
                    will provide additional protection for drink-
                    ing water supplies. Drinking water supplies
                                             include ground water, individual and com-
                                             munity wells, lakes, reservoirs, and munici-
                                             pal water treatment facilities.
                                                Finally, buffer zones help maintain good
                                             relations with the surrounding community by
                                             protecting surrounding areas from noise,
                                             dust, and odor that may be associated with a
                                             unit. Buffer zones also help prevent access by
                                             unauthorized people. For units located near
                                             property boundaries, houses, or historic
                                             areas, evergreen trees or earthen berms can
                                             provide 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.

                                             A.     Recommended Buffer
                                                Check with state and local officials to
                                             determine what buffer zones may apply to
                                             industrial waste management units.14
                                                Property boundaries. Waste management
                                                units can present noise, odor, and dust
                                                problems for residents or businesses locat-
                                                ed on adjacent property, thereby diminish-
                                                ing property values.  Additionally, proximi-
                                                ty to property boundaries can invite
                                                increased trespassing, vandalism, and
                                                Drinking water wells, surface-water bod-
                                                ies, 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 pub-
                                                lic water supplies, such as a community
                                                well or water treatment facility, also raises
                                                concerns. Releases from a waste manage-
                                                ment unit may pose serious threats to
                                                human health not only where water is
                                                used for drinking, but also where surface
                                                waters are used for recreation.
^Natural attenuation may be defined as chemical and biological processes that reduce contaminant con-

^Appendix IV presents a summary of some state buffer zone recommendations.


                                                                               Getting Started—Considering the Site
Buffer zones can help protect endangered
species and their habitats.
  Contamination of surface waters also
  threatens plants and animals and their
  Houses or buildings. To minimize adverse
  effects on adjacent properties, consider
  incorporating a buffer zone or separation
  distance into unit design. Consider planting
  trees or bushes to provide a natural buffer
  between a unit and adjacent properties.

B.     Additional  Buffer Zones
  There are several other areas for which to
consider establishing buffer zones, including
critical habitats, park lands, public roads, 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
modification of a critical habitat and mini-
mize harm to endangered or threatened

Parklands. A buffer between a unit and
park boundaries helps maintain the aes-
thetics of the park land. Park lands pro-
vide recreational opportunities and a nat-
ural refuge for wildlife. Locating a unit too
close to these areas can disrupt recreational
qualities and natural wildlife patterns.
Public roads. A buffer zone will help
reduce unauthorized access to a 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 proximi-
ty to one of these sites may adversely
impact the aesthetic quality of the site.
These  areas include historic settlements,
battlegrounds, cemeteries, and Indian bur-
ial grounds. Check also whether a prospec-
tive site itself has historical or archaeologi-
cal significance.
 Historic sites call for careful consideration
 of buffer zones.
l->For the full text of the Endangered Species Act, go to the U.S. House of Representatives Internet Law
Library at <lawJhouse.govA6.htm>.


Getting Started—Considering the Site
                      In summary, check with local authorities
                   to ensure that placement of a new waste man-
                   agement unit or lateral expansion of an exist-
                   ing unit will not conflict with any local buffer
                   zone criteria. Also, review any relevant state
                   regulations that may specify buffer zones for
                   industrial waste management units. For new
                   units or lateral expansions of existing units
                   located near any sensitive areas as described in
                   this section,  consider measures to minimize
                   any possible health, environmental, and nui-
                   sance impacts.

                   III.   Local  Land Use

                          and Zoning

                      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 represent different use
                   categories, such as residential, commercial,
                   industrial, or agricultural. Zoning protects
                   public health and safety, property values, and
                   development trends. Consider the compati-
                   bility of a  unit with nearby existing and
                   future land use and contact local authorities
                   early in the siting process. Local planning,
                   zoning, or public works officials can discuss
                   the development of a .unit, compliance with
                   local regulations, and available options. Local
                   authorities may impose conditions for pro-
                   tecting adjacent properties from potential
                   adverse impacts of unit.
                     Addressing local land use  and zoning
                   issues during the siting process may prevent
                   these issues  from becoming prominent con-
                   cerns later in the process. Land use and zon-
                   ing restrictions often address impacts on
                   community and recreational  areas, historical
                   areas, and other critical areas. Consider the
proximity of a unit to such areas and evaluate
any potential adverse effects it may 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 actions may be brought by local authori-
ties or nearby property owners.

   In situations where land use and zoning
restrictions may 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 activities may reduce
impacts on nearby properties.  In addition, it
may 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 a unit.
IV.  Environmental


  In the past several years, there has been
growing recognition from communities and
federal and state governments that some
socioeconomic and racial groups may bear a
disproportionate burden of adverse environ-
mental effects  from waste management activi-
ties. President Clinton issued Executive Order
12898, Federal Actions to Address
Environmentaljusti.ee in Minority Populations
and Low-Income Populations, on February 11,


                                                                              Getting Started—Considering the Site
1994. To be consistent with the definition of
environmental justice in this executive order,
identify and address, as appropriate, dispro-
portionately high and adverse human health
or environmental effects of waste manage-
ment programs, policies, and activities on
minority populations and low-income popu-
   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 bene-
fits. During unit siting or expansions, address
environmental justice
concerns in a manner
that is most appropriate
for the operations, the
community, and the
state. Look for opportu-
nities to  minimize envi-
ronmental impacts,
improve the surrounding
environment, and pur-
sue opportunities to
make the waste manage-
ment 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 knowledge
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,
neighborhood, and state. There is no such
thing as a "one-size-fits-all" public involve-
ment program.  Listening to each other
carefully will identify the specific environ-
mental justice concerns and determine the
involvement activities most appropriate to
address those needs.
Provide interpreters for public meetings.
Interpreters can be used to ensure the
information is exchanged. Provide inter-
preters, as needed, for the hearing
impaired and for any languages,  other than
                     English, spoken by
                     a significant per-
                     centage of the audi-
                     Provide multilingual
                     fact sheets and
                     other information.
                     Public notices and
                     fact sheets should
                     be distributed in as
                     many languages as
                     necessary to ensure
                     that all interested
parties receive necessary information. Fact
sheets should be available for the visually
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 envi-
ronmental justice panels comprised of
community members, industry, and state
representatives. The panels meet monthly
to discuss environmental justice issues and
find solutions to any concerns identified
by the group.


Getting Started—Considering the Site
                              Considering  the Site Action Items
         General Location Considerations
         Q     Check to see if the proposed unit site is
                —    In a 100-year floodplain;
                —    Near a wetland;
                —    Within 200 feet of an active fault;
                —    In a seismic impact zone;
                —    In an unstable area;
                —    Close to an airport; or
                —    Within a wellhead protection area.

         Q     If the proposed unit site is in any of these areas,
                —    Attempt to site the unit elsewhere first; or
                —    Design the unit to account for the area's characteristics and mitigate the unit's
                       impacts on such areas.

         Buffer Zones
         (Many states require bufifer zones between waste management units and other nearby land uses.)

         D     Check to see if the proposed unit site is near
                —    A property boundary;
                —    A drinking water well;
                —    A public water supply, such as a community well, reservoir, or water treatment
                —    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; or
                —    Historic or archaeological sites.

         D     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.


                                                                         Getting Started—Considering the Site
             Considering the  Site Action  Items (cont.)
Local Land Use and Zoning Restrictions
Q     Contact local planning, zoning, and/or public works agencies to discuss restrictions that may
       apply to the unit.

D     Comply with any applicable restrictions, or obtain the necessary variances or exceptions.

Environmental Justice Issues
Q     Determine whether minority or low-income populations would bear a disproportionate burden of any
       environmental effects of the unit's waste management activities.

Q     Work with the community to devise strategies to minimize any potential disproportionate burdens.


Getting Started—Considering the Site
         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.

         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

         Oregon Department of Environmental Quality. 1996. Wellhead protection facts. World Wide Web page:

         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 applica-
         tions. 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 ]

         U.S. Army Corps of Engineers. 1984. Engineering and design: Use of geotextiles under riprap. ETL 1110-2-

         U.S. EPA. 1995. Decision-maker's guide to solid waste management, 2nd ed. EPA530-R-95-023.

         U.S. EPA. 1995. RCRA Subtitle D (258) Seismic design guidance for municipal solid waste landfill facilities.

         U.S. EPA. 1995. Why do wellhead protection? Issues and answers in protecting public drinking water supply
         systems.  EPA813-K-95-001.

         U.S. EPA. 1994. Design, operation, and closure of municipal solid waste landfills. EPA625-R-94-008.


                                                                          Getting Started—Considering the Site
                                 Resources  (cont.)
U. S. EPA. 1994. Handbook: Ground water and wellhead protection. EPA625-R-94-001.

U. S. EPA. 1993. Guidelines for delineation of wellhead protection areas. EPA440-5-93-001.

U.S. EPA. 1993. RCRA Public involvement manual. EPA530-R-93-006.

U.S. EPA. 1993. 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-93-001.

U. S. EPA. 1991. Protecting local ground-water supplies through wellhead protection.

U.S. EPA. 1990. Sites for our solid waste: A guidebook for effective public involvement.

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. House of Representatives. 1996. Endangered Species Act. Internet Law Library. World Wide Web
page: <daw.house.gov/16.htm>.

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.



        Part II
Protecting Air Quality
      Chapter 5
Protecting Air Quality


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 Emissions Standards for Hazardous Air Pollutants 5-4
   D.Title V Operating Permits  5-4
   E. Federal Airborne Emission Regulations for Solid Waste Management Activities   5-9
         1.   Hazardous Waste Management Unit Airborne Emission Regulations     5-9
         2.   Municipal Solid Waste Management Landfill Airborne Emissions Regulations  5-9
         3.   Off-Site Waste and Recovery Operations NESHAP 5-9
   E A Decision Guide to Applicable CAA Requirements    5-10

II. Assessing Risk  5-14
   A. Assessing Risks Associated with Inhalation of Ambient Air     5-15
   B.IWAIR Model    .'  5-19
         1.   Emissions Model   5-19
         2.   Dispersion Model  5-19
         3.   Risk Model    ...5-20
         4.   Estimation Process    5-20
         5.   Capabilities and  Limitations of the Model    5-23
   C. Site-Specific Risk Analysis   5-25

III. Emission Control Techniques    5-25
   A. Controlling Particulate Matter (PM)   5-25
         1.   Vehicular Operations  5-27
         2.   Waste Placement and Handling  5-27
         3.   Wind Erosion  5-29
   B. VOC Emission Control Techniques   5-29
         1.   Choosing a Site to Minimize Airborne Emission Problems    5-29
         2.   Pretreatment of Waste 5-30
         3.   Enclosure, of Units   5-30
         4.   Treatment of Captured VOCs    5-30
         5.   Special Considerations for Land Application Units 5-32

Protecting Air Quality Action Items 5-33

Resources   5-34


                                   Table  of Contents
    Figure 1. Evaluating VOC Emission Risk  5-11
    Figure 2. Conceptual Site Diagram   5-15
    Figure3. Emissions from WMU 5-17
    Figure 4. Forces That Affect Contaminant Plumes 5-18
    Figure 5. IWAIR Approach for Developing Risk or Protective Waste Concentrations 5-21
    Figure 6. Screen 1, Method, Met Station. WMU    5-22
    Figure 7. Screen 2, Waste Managed   5-22

    Table  1. Industries for Which NSPSs Have Been Established  5-5
    Table  2. Hazardous Air Pollutants (HAPs) Defined in Section 112 of the Clean Air Act
            Amendments of 1990  •.  5-6
    Table  3. Source Catagories with MACT Standards 5-8
    Figure 4. Major Source Determination in Nonattainment Areas 5-12
    Table  5. Source Characterization Models    5-26



                                                                 Protecting Air Quality—Protecting Air Quality
                       Protecting  Air  Quality
   Airborne particulates and toxic air emissions can cause human
   health risks and damage the environment.  Adopt controls to mini-
   mize particulate emissions.   If a facility's waste management units
   are not addressed by requirements under the  Clean Air Act, assess
   risks associated with toxic air emissions using the model in this
   guidance, and implement  pollution prevention, treatment, or con-
   trols to reduce risks.  For facilities that must obtain a Clean Air Act
   Title V permit, the permit is a good vehicle to address air emissions
   from 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 impacts
depend on many factors, including the quan-
tity of air pollution to which people are
exposed, the duration of exposures, and the
effects associated with specific pollutants. An
air risk assessment takes these factors into
account to project  risks posed at a particular
site or facility. Air releases from waste man-
  This chapter wiE help you address the
  following questions:    "    ,  -
  • Is a particular facility subject to CAA
  * What is. an air risk assessment?
  • Do waste management .units pose risks
  from volatile air emissions?-
  * What controls will; reduce particulate
  and volatile emissions from a facility?
agement units include particulates or wind-
blown dust and toxic or hazardous contami-
nants. Toxic air pollutants are those pollu-
tants known or suspected to cause cancer or
other serious health effects such as reproduc-
tive effects or birth defects, or to cause
adverse environmental effects.1
  We recommend that every facility imple-
ment controls to address emissions of air-
borne particulates. Particulates have immedi-
ate and highly visible impacts on surrounding
neighborhoods. They can affect human health
and may carry hazardous constituents off site
as well. Generally, controls are consistent with
good operating practices, and may not be too
  For toxic air releases from industrial solid
waste management units, there are two sets of
questions you need to pursue. First, what reg-
ulatory requirements under the Clean air Act
(CAA) apply to the facility, and do those
requirements address waste management
units? The second question for facilities whose
waste management units are not addressed by
CAA requirements, is "are there risks from
toxic air releases that should be controlled?"
'From "Taking Toxics Out of the Air: Progress in Setting Maximum Achievable Control Technology: Standards
Under the Clean Air Act" U.S. EPA, Office of Air Quality Planning and Standards, Research Triangle Park, NC
27711, EPA451-K-98-001, February 1998.


Protecting Air Quality—Protecting Air Quality
                      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 may
                    apply to a facility. Each facility subject to any
                    of these requirements must obtain a CAA Title
                    V operating permit. The decision guide will
                    help you to 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,  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 may find that waste management units
                    are not addressed or that a specific  facility
                    dearly does not fit into any regulatory catego-
                    ry 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.
We recommend a two-tiered approach to this
assessment, depending on the complexity and
amount of site specific data you have.

   Limited site-specific air assessment: The CD
   ROM version of this 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 emis-
   sions pose a risk that warrants additional
   emission controls or that could be
   addressed more effectively with pollution
   prevention or waste treatment before place-
   ment in the waste management unit.

   Comprehensive Risk Assessment: This assess-
   ment relies on a comprehensive analysis of
   waste and site-specific data and use of
   models designed to assess multi-pathway
   exposures to airborne contaminants. There
   are a number of modeling tools available
   for this analysis. Consult closely with your
   air quality management agency as you pro-
                     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.


                                                                 Protecting Air Quality—Protecting Air Quality
I.     Federal Airborne

       Emission  Control

  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, see Appendix I or
visit the Technology Transfer Network, EPA's
premier technical web site for information
transfer and sharing related to  air pollution
topics, at <www.epa.gov/ttn>.
  If the facility is subject to any CAA
requirements, the owners must obtain a per-
mit under Tide V of CAA and/or other state
air permitting programs. As part of the per-
mitting process, develop an emissions inven-
tory for the facility. Some states have addi-
tional permitting requirements. Whether or
not emissions from a waste management
unit(s) 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 pru-
dent, however, where there are no applicable
air permit requirements to assess whether
there may be risks associated with waste
management units and  to address these risks.
directly by EPA. Instead, each state must sub-
mit 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, which can be pre-
cursors to ozone, the waste management unit
could be affected by EPA's revised NAAQS for
ground-level ozone.3 EPA will phase out and
replace the previous 1-hour averaging time
ozone standard widi a new 8-hour averaging
time standard to protect over longer exposure
periods. The previous 1-hour standard of
0.12 parts per million (ppm) will be replaced
with a new 8-hour standard of 0.08 ppm.
Phasing in the new standard will take place in
several ways. States or areas of states that
have not been able to comply with current
0.12 ppm 1-hour standard will not be subject
to more stringent requirements until they
meet the 1-hour standard for three consecu-
tive years. States and areas already achieving
the 1-hour standard may be eligible to partic-
ipate in regional emission control strategies or
submit early SIPs to address the new 8-hour
standard. Consult with your state to deter-
mine whether efforts to comply with the
ozone NAAQS involve VOC emission limits
that apply to a specific facility.
A.    National Ambient Air
       Quality Standards
   The CAA authorizes EPA to establish emis-
sion limits to achieve National Ambient Air
Quality Standards (NAAQS).2 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 (NAAQD)). NAAQS are not enforced
B.     New Source
       Performance  Standards
  New Source Performance Standards
(NSPSs) may apply to any building, structure,
facility, or installation which emits or may emit
an air pollutant for which a NAAQS (criteria
pollutants) exists. For industry categories,
NSPSs establish national technology-based
emission limits for criteria air pollutants,7 such
as paniculate matter (PM), or for their precur-
sors, such as VOCs. States have primary
responsibility for assuring that the NSPSs are
followed. These standards are distinct from
H2 U.S.C. § 7409
362 FR 38856 Quly 18, 1997)


Protecting Ak Quality—Protecting Air Quality
                    NAAQS because they establish direct national
                    emission limits for specified 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 loca-
                    tions of the NSPSs in the Code of Federal
                    Regulations. Check  to see if any of the 74 New
                    Source Performance Standards (NSPSs)4 apply
                    to the facility.5 Any facility subject to a NSPS
                    must obtain a Title V operating permit (see sec-
                    tion D below.).

                    C     National  Emission Stan-
                           dards for Hazardous Air
                      Waste streams that are not hazardous waste
                    under RCRA may generate air pollutants that
                    have a hazardous air pollutant (HAP) regulato-
                    ry status under the CAA. Section 112 of the
                    CAA Amendments  of 19906 requires EPA to
                    establish national standards to reduce HAP
                    emissions. Section  112(b) contains a list of
                    188 HAPs (see Table 2) to be regulated by
                    National Emission Standards  for Hazardous
                    Air Pollutants (NESHAPs) or  Maximum
                    Achievable Control Technology (MACT) stan-
                    dards, that are generally set on an industry-by-
                    industry basis.
                      MACT standards apply only to major
                    sources. A major source is defined  as any sta-
                    tionary 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 emis-
                    sions, including emissions from waste manage-
                    ment units, are to be  taken into account in
                    determining whether a stationary source is a
major source. Each MACT standard limits spe-
cific operations, processes, and/or wastes that
are covered. Some MACT standards specifical-
ly cover waste management units, others do
not. If a facility is covered by a MACT stan-
dard, it must be permitted under Title V (see
   EPA has identified approximately 170 indus-
trial categories and subcategories that are or will
be subject to MACT standards. The CAA calls
for EPA to promulgate the standards in four
phases. Standards already promulgated in the
first two phases are listed in Table 3.  The sched-
ule for the last two phases extends through
2000 (see Appendix I).
   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. 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 determination. A
draft of this report was submitted to Congress
on April 14, 1998, and the final version is due
February 1, 1999. If significant residual risk
exists after application of a MACT, EPA must
promulgate health-based standards for that
source category to further reduce HAP emis-
sions. EPA must set residual risk standards with-
in 9 years after promulgation of each NESHAP
in the first phase  group and within 8 years for
all other phases of source categories.
 D.     Title V Operating Permits
   For many facilities, the new federal operat-
 ing permit program established under Title V
 of the CAA will cover all sources of airborne
 emissions. It requires a permit for any facility
                    "40 CFR Part 60

                    'While NSPSs apply to new facilities, EPA also established emissions guidelines for existing facilities.

                    "42 U.S.C. § 7412.


                                                                                     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 <earth1.epa.gov/epacfr40/
chapt-l.info/subch-C/40P0060/>.  Be sure to check the Federal Register for updates that may have been
published after this guidance.
Part 60
40 CFR
Part 60
 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
 Electric Utility Steam Generating Units after 9/18/78 DA
 Equipment Leaks of VOC in Petroleum Refineries  GGG
 Equipment Leaks of VOC in SOCMI               W
 Ferroalloy Production Facilities                   Z
 Flexible Vinyl & Urethane Coating & Printing      FFF
 Fossil-fuel 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-Commercial-Institutional Steam Gen.
   Unit                                          DB
 Kraft Pulp Mills                                 BB
 Large Municipal Waste Combustors after 9/20/94   EB
 Lead-Acid Battery Manufacturing Plants            KK
 Lime Manufacturing                            HH
 Magnetic Tape 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 (MWQ             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: SO^ 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.   VW
                 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             BBB
                 Secondary Brass and Bronze Production Plants    M
                 Secondary Lead Smelters                       L
                 Sewage Treatment Plants                       O
                 Small IndustyCommyinstitut. Steam
                   Generating Units                            DC
                 SOCMI - Air Oxidation Processes                III
                 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            K
                 Storage Vessels for Petroleum Liquids            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


Protecting Air Quality—Protecting Air Quality
                                                            Table 2
                                  HAPs Defined in Section  112 of the CAA Amendments of 1990
I • ' i i I
75070 Acetaldehyde
60355 Acetamide
75058 Acetonitrile
98862 Acetophenone
53963 2-Acetylaminofluorene
107028 Acrolein
79061 Acrylamide
79107 Acrylic acid
107131 Acrylonitrile
107051 Allyl chloride
92671 4-Aminobiphenyl
62533 Aniline
90040 o-Anisidine
1332214 Asbestos
71432 Benzene (including benzene
from gasoline)
92875 Benzidine
98077 Benzotrichloride
100447 Benzyl chloride
92524 Biphenyl :
117817 Bis(2-ethylhexyl)
phthalate (DEHP)
542881 Bis(chloromethyl)ether
75252 Bromoform
106990 1,3-Butadiene
156627 Calcium cyanamide
133062 Captan
63252 Carbaryl
75150 Carbon disulfide
56235 Carbon tetrachloride
463581 Carbonyl sulfide .
120809 Catechol
133904 Chloramben
57749 Chlordane
7782505 Chlorine
79 1 18 Chloroacetic acid
532274 2-Chloroacetophenone
108907 Chlorobenzene
510156 Chlorobenzilate
67663 Chloroform
107302 Chloromethyl methyl ether
126998 Chloroprene
1319773 Cresols/Cresylic acid
(isomers and mixture)
95487 o-Cresol
108394 m-Cresol
106445 p-Cresol
98828 Cumene
94757 2,4-D, salts and esters
3547044 DDE
334883 Diazomethane
132649 Dibenzofurans
96128 l,2-Dibromo-3-
84742 Dibutylphthalate
106467 l,4-Dichlorobenzene(p)
91941 3,3-Dichlorobenzidene
111444 Dichloroethyl ether
542756 1,3-Dichloropropene
62737 Dichlorvos
111422 Diethanolamine
121697 N,N-Diethyl aniline
(N ,N-Dimethylaniline)
64675 Diethyl sulfate
119904 3,3-Dimethoxybenzidine
60117 Dimethyl aminoazobenzene
119937 3,3'-Dimethyl benzidine
79447 Dimethyl carbamoyl chloride
68122 Dimethyl formamide
57 147 1 , 1-Dimethyl hydrazine
13 1 1 13 Dimethyl phthalate
77781 Dimethyl sulfate
534521 4,6-Dinitro-o-cresol, and
51285 2,4-Dinitrophenol
121142 2,4-Dinitrotoluene
123911 1,4-Dioxane
(1 ,4-Diethyleneoxide)
122667 1,2-Diphenylhydrazine
106898 Epichlorohydrin (1-Chloro-
106887 1,2-Epoxybutane
140885 Ethyl acrylate
100414 Ethyl benzene
51796 Ethyl carbamate (Urethane)
75003 Ethyl chloride
106934 Ethylene dibromide
107062 Ethylene dichloride
(1 ,2-Dichloroethane)
107211 Ethylene glycol
151564 Ethylene imine (Aziridine)
75218 Ethylene oxide
96457 Ethylene thiourea
75343 Ethylidene dichloride
(1 , 1-Dichloroethane)
50000 Formaldehyde
76448 Heptachlor
118741 Hexachlorobenzene
87683 Hexachlorobutadiene
77474 Hexachlorocyclopentadiene
67721 Hexachloroethane
822060 Hexamethylene-1,6-
680319 Hexamethylphosphoramide
110543 Hexane
302012 Hydrazine
7647010 Hydrochloric acid
7664393 Hydrogen fluoride
(Hydrofluoric acid)
123319 Hydroquinone
78591 Isophorone
58899 Lindane (all isomers)
108316 Maleic anhydride
67561 Methanol
72435 ; Methoxychlor
74839 ' Methyl bromide
74873 Methyl chloride
71556 , Methyl chloroform
(1, 1, 1-Trichloroe thane)
78933 Methyl ethyl ketone
60344 Methyl hydrazine
74884 Methyl iodide
108101 Methyl isobutyl ketone
624839 Methyl isocyanate
80626 Methyl methacrylate
1634044 Methyl ten butyl ether
1 0 1 144 4,4-Methylene bis(2
75092 Methylene chloride
101688 Methylene diphenyl
diisocyanate (MDI)
101779 4,4'-Methylenedianiline
91203 Naphthalene
98953 Nitrobenzene
92933 4-Nitrobiphenyi
100027 4-Nitrophenol
79469 2-Nitropropane
684935 N-Nitroso-N-methylurea
62759 N-Nitrosodimethylamine
59892 N-Nitrosomorpholine
56382 Parathion
82688 Pentachloronitrobenzene
87865 Pentachlorophenol


                                                                                  Protecting Air Quality—Protecting Air Quality
                                          Table 2 (continued)
                   HAPs Defined in Section  112 of the CAA Amendments of 1990
 108952  Phenol
 106503  p-Phenylenedlamine
 75445   Phosgene
 7803512 Phosphine
 7723140 Phosphorus
 85449   Phthalic anhydride
 1336363 Polychlorinated
         biphenyls (Aroclors)
 1120714 1,3-Propane sultone
 57578   beta-Propiolactone
 123386  Propionaldehyde
 114261  Propoxur (Baygon)
 78875   Propylene dichloride
 75569   Propylene oxide
 75558   1,2-Propylenimine
         (2-Methyl aziridine)
 91225   Quinoline
 106514  Quinone
 100425  Siyrene
 96093   Styrene oxide
 1746016 2,3,7,8-Tetrachlorodi-
79345   1,1,2,2-Tetrachloroethane

127184 Tetrachloroethylene
7550450 Titanium tetrachloride
108883 Toluene
95807   2,4-Toluene diamine
584849 2,4-Toluene diisocyanate
95534   o-Toluidine
8001352 Toxaphene (chlorinated
20821   1,2,4-Trichlorobenzene
79005   1,1,2-Trichloroethane
79016   Trichloroethylene
95954   2,4,5-Trichlorophenol
88062   2,4,6-Trichlorophenol
121448 Triethylamine
582098 Trifluralin
540841 2,2,4-Trimethylpentane
108054 Vinyl acetate
593602 Vinyl bromide
75014   Vinyl chloride
75354   Vinylidene chloride
1330207 Xylenes (isomers and
95476   o-Xylenes
108383  m-Xylenes
106423  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 Matter1
[none]   Radionuclides (incl. radon)c
[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.
'X'CN where X = H1 or any other group where a formal dissociation may occur. For example KCN or Ca(CN)2.
'Includes mono- and di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol R-(OCH2CH2)n-OR' where n = 1, 2,
or 3, R = alkyl or aryl groups, and R1 = R, H, or groups which, when removed, yield glycol ethers with the structure: R-
(OCH2CH)n-OH.  Polymers are excluded from the glycol category
'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.
•"Includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100 °C.
CA type of atom which spontaneously undergoes radioactive decay.
   emitting or having the potential to emit more
   than 100 tpy of any air pollutants.7 Permits
   are also required for all sources subject to
   MACT or NSPS standards. All airborne emis-
   sion requirements that apply to an industrial
   facility, including emission limitations as well
   as operational, monitoring, and reporting
   requirements, will be incorporated in its oper-
   ating permit. A Title V permit provides a sin-
   gle tool to address all emissions from facilities
   subject to CAA requirements.
                      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 (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
    'Under CAA Section 302(g), "air pollutant" is defined as any pollutant agent or combination of agents, includ-
    ing any physical, chemical, biological, or radioactive substance or matter -which is emitted into or otherwise
    enters the ambient air.


Protecting Air Quality—Protecting Air Quality
                                                                   Table 3
                                                 Source Categories With MACT Standards*
                  Source Category
                           Federal Register Page
Source Category
 Federal Register  Page
                  Non-Ferrous Metals Processing
                  Secondary Lead Smelling     60 FR 32587 (6/23/95)
                  Primary Aluminum Reduction 62 FR 52383 (10/7/97)
                  Primary Copper Smelting     63 FR 19582 (4/20/98)(P)
                  Primary Lead Smelting       63 FR 19200 (4/17/98)(P)
                   Coke Ovens
                   Steel Pickling HCI Process
                  Mineral Products Processing
                  Mineral Wool Production
                  Portland Cement
                  Wool Fiberglass
                           58 FR 57898 (10/27/93)

                           62 FR 25369 (5/8/97) (P)

                           63 FR 14181 (3/24/98XP)

                           62 FR 15227 (3/21/97) (P)
                   Petroleum and Natural Gas Production and Refining
                   Oil & Natural Gas Production 63 FR 06288 (2/6/98)(P)
                   Natural Gas Transmission and
                   Storage                    63 FR 06288 (2/6/98)(P)
                   Petroleum Refineries         60 FR 43244 (8/18/95)
                   liquids Distribution
                   Gasoline Distribution
                   Marine Vessel Loading

                   Surface Coating Processes
                   Aerospace Industries
                   Magnetic Tapes
                   Shipbuilding and Repair
                   Wood Furniture

                   Waste Treatment and Disposal
                   Off-Site Waste and Recovery
                           59 FR 64303 (12/14/95)
                           60 FR 48399 (9/19/95)
                           60 FR 45948 (9/1/95)
                           59 FR 64580 (12/15/94)
                           61 FR 27132 (5/30/96)
                           60 FR 64330 (12/15/95)
                           60 FR 62930 (12/7/95)
                           61 FR 34141 (7/1/96)
                   Agricultural Chemicals Production
                   Agricultural Chemicals
                   Production                 62 FR 60565 (11/10/97) (P)

                   Pharmaceutical Production Processes
                   Pharmaceutical Production    62 FR 15753 (4/2/97) (P)

                   Polymers and Resins Production
                   Aoylonkrile-Butadiene-Styrene 61 FR 48207 (9/12/96)
                   Butyl Rubber
                   Epichlorohydrin Elastomers
                   Epoxy Resins Production
                   Ethylene-Propylene Rubber
                   Flexible Polyurethane Foam
                            61 FR 46905 (9/5/96)
                            61 FR 46905 (9/5/96)
                            60 FR 12670 (3/8/95)
                            61 FR 46905 (9/5/96)
                            61 FR 68405 (12/27/96) (P)
 Methyl Methacrylate-Acrylo-
   nitrile-Butadiene-Styre ne
 Methyl Methacrylate-Buta-
   diene-Styrene Terpolymers
 Nitrile Butadiene Rubber
 Nitrile Resins Production
 Non-Nylon. Polyamides
 Polybutadiene Rubber
 Polyether Polyols
 Polyethylene Terephthalate
 Polysulfide Rubber
 Styrene-Butadiene Rubber,
61FR 46905 (9/5/96)

61FR 48207 (9/12/96)

61 FR 48207 (9/12/96)
61FR 46905 (9/5/96)
61FR 46905 (9/5/96)
61 FR 48207 (9/12/96)
60 FR 12670 (3/8/95)
61FR 46905 (9/5/96)
62 FR 46803 (9/4/97) (P)
61 FR 48207 (9/12/96)
61 FR 48207 (9/12/96)
61FR 46905 (9/5/96)
61 FR 48207 (9/12/96)

61 FR 46905 (9/5/96)
                                                        Production of Inorganic Chemicals
                                                        Phosphate Fertilizers      .
                                                        Production                61 FR 68429 (12/27/96) (P)
                                                        Phosphoric Acid
                                                        Manufacturing             61 FR 68429 (12/27/96) (P)
 Production, of Organic Chemicals
 Synthetic Organic Chemicals 59 FR 19402 (4/22/94),
                                                                                  62 FR 2721 (1/17/97)
 Miscellaneous Processes
 Chromic Acid Anodizing
 Commercial Dry Cleaning
 Commercial Sterilization
    Facilities              ;
 Decorative Chromium
 Halogenated Solvent
 Hard Chromium
 Industrial Cleaning
 Industrial Dry Cleaning
 Industrial Process Cooling
 Pulp and Paper Production
60 FR 4947 (1/25/95)

58 FR 49353 (9/22/93)

59 FR 62585 (12/6/94)

60 FR 4948 (1/25/95)

59 FR 61801 (12/2/94)

60 FR 4948 (1/25/95)

58 FR 49353 (9/22/93)

58 FR 49353 (9/22/93)

59 FR 46339 (9/8/94)
63 FR 18503 (4/15/98)

62 FR 44614 (8/22/97) (P)
* This table contains final rules and proposed rules (P) promulgated as of May 1998.  It does not
identify corrections or clarifications to rules.


                                                                   Protecting Air Quality—Protecting Air Quality
 controls under CAA regulations. (See
 Appendix II for a listing of EPA regional and
 state air pollution control agency contacts.)

 E.     Federal  Airborne
        Emission  Regulations for
        Solid Waste
        Management Activities
   While EPA has not established airborne
 emission regulations for nonhazardous indus-
 trial waste management units under RCRA,
 standards developed for hazardous waste man-
 agement units and municipal solid waste land-
 fills (MSWLFs) may serve as a guide in evalu-
 ating 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 monitoring and
 control of airborne emissions from hazardous
 waste treatment, storage, and disposal facili-
 ties. Subparts AA, BB,  and CC of 40 CFR Part
 265 address VOC releases from process vents,
 equipment leaks,, tanks, surface impound-
 ments, and containers. (See Appendix III for
 a more detailed discussion of Subparts AA,
 BB, and CC.) Subpart  CC establishes require-
 ments for hazardous waste surface impound-
 ments containing waste with volatile organic
 content greater than 500 ppm by weight. It
 exempts units managing wastes that have
 been treated to  reduce concentrations of
 organics. For non-exempt surface impound-
 ments, Subpart CC requires the use  of covers
 and closed vent systems that reduce VOC
 emissions by 95 percent. Closed vent systems
 include vapor recovery units, flares,  and
 other combustion units.
2.   Municipal Solid Waste Landfill
Airborne Emission Regulations
   On March 12, 1996, EPA promulgated air-
borne emission regulations for new and exist-
ing MSWLFs.8 These regulations apply to all
new MSWLFs constructed on or after May 30,
1991 and to existing landfills with total design
capacities of 2.5 million megagrams per year
(Mg/yr) (approximately 2.75 million tpy) that
have accepted waste on or after November 8,
1987. In addition to methane, MSWLFs  poten-
tially emit criteria pollutants and HAPs in the
gases generated during waste decomposition, as
well as in combustion of the gases in control
devices, and from other sources, such as dust
from vehicle traffic and emissions from leachate
treatment facilities or maintenance shops.
Under the regulations, any affected MSWLF
that emits more than 50 Mg/yr (55 tpy) of non-
methane organic compounds (NMOC) is
required to install controls.

  Best demonstrated technology requirements
for both new and existing municipal landfills
prescribe installation of a well-designed and
well-operated gas collection system' and a con-
trol device. The collection system should be
designed to allow expansion for new cells that
require controls. The control device (presumed
to be a combustor) must demonstrate either an
NMOC reduction of 98 percent by weight in
the collected gas or an outlet NMOC concen-
tration of no more than 20 parts per million by
volume (ppmv).

3.  Off-Site Waste and Recovery
Operations NESHAP
  On July 1, 1996, EPA established standards
for off-site waste and recovery operations
(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 or any combination of
HAPs. It must receive waste, used oil, or  used
961 ER 9905



Protecting Air Quality^-Protecting Air Quality
                    solvents from off-site that contain one or more
                    HAPs.10 In addition, the facility must operate
                    one of the following: a hazardous waste treat-
                    ment, storage, or disposal facility; RCRA-
                    exempt hazardous wastewater treatment opera-
                    tion, nonhazardous wastewater treatment facili-
                    ty other than a publicly owned treatment facili-
                    ty; RCRA-exempt hazardous waste recycling or
                    reprocessing operation, 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 equip-
                    ment leaks. For example, OSWRO establishes
                    two levels of air emission controls for tanks
                    depending on tank design capacity and die
                    maximum organic HAP vapor pressure of the
                    off-site material in the tank. For process vents,
                    control devices must achieve a minimum of 95
                    percent organic HAP emission control. To con-
                    trol HAP emissions from equipment leaks, the
                     facility must implement leak  detection and
                     repair work practices and equipment modifica-
                     tions for those equipment components contain-
                     ing or contacting off-site waste having a total
                     organic HAP concentration greater than 5 per-
                     cent by weight.

                     F.     A  Decision Guide to
                             Applicable CAA
                        The following series of questions is designed
                     to help you identify CAA requirements that
                     may 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 permitting authorities to deter-
                     mine which requirements apply to  a specific
                     facility and whether such requirements address
waste management units at the facility. If a
facility is clearly not subject to CAA require-
ments, we recommend that you assess potential
risks from VOC emissions at a waste manage-
ment unit using the IWAIR or a site-specific
risk assessment.
   The following steps provide a walk through
of this evaluation process:
    1.  Determine emission from the unit:
    a)  Determine VOC's present in the waste
    (waste characterization). Then assume all
    the VOC's are emitted from the unit; or
    b)  Estimate emissions using an emissions
    model. This also requires waste characteri-
    zation. 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 modeling tool for
    this guidance; or
    c)  Measure emissions from the unit. This
    is the most resource intensive alternative.
    2.  Is the waste management unit part of
    an industrial facility which is subject to a
    CAA Tide 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.11 As part of the per-
 mitting process, the facility should develop, an
 emissions inventory. Some states have addition-
 al permitting requirements. If a facility is sub-
 ject to a Title V operating permit, all airborne
 emission requirements that apply to an indus-
 trial facility, including emission limitations as
 well as operational, monitoring, and reporting
 requirements, will be incorporated in its oper-
 ating permit. Consult with appropriate federal,
 state, and local air program staff to determine
 whether your waste management unit is sub-
 ject to air emission limits and controls.12
                     "OSWRO identified aprdximatery 10 HAPs to be covered, This HAP list is a subject of the CAA Section 112 list

                     "EPA can designate additional source categories subject to Title V operating permit requirements.

                     "Implementation of air emission controls may generate new residual waste. Ensure that these wastes are
                     managed appropriately, in compliance with state requirements and consistent with this guidance.


                                                                       Protecting Air Quality—Protecting Air Quality
                 Figure 1. Evaluating VOC  Emission  Risk
|    Characterize waste for potential air emissions    |
                  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 MACT standards; or
        d. subject to the acid rain program; or
               e. a unit subject to the
                OSWRO NESHAP?
                                       the permit
                                   specifically address\7^
                                   waste managemen
Facility is subject
to an air permit.
                     the waste
                 contain any of the
                     95 listed
        Conduct a risk evaluation using either.
  a. Industrial Waste Air
b. Site-specific risk
                                                     Conduct a more site-specific
                                                           risk assessment
                      the total
                  risk for the unit
                                                    Reduce risk to acceptable levels
                                                   using treatment, controls or waste
       Operate the unit in accordance with the
         recommendations of this guidance.


Protecting Air Quality—Protecting Air Quality
                       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 permit-
                    ting authority.
                       Whether or not emissions from waste man-
                    agement unit(s) will be specifically addressed
                    through the permit process depends on a num-
                    ber of factors, including the type of facility and
                    CAA requirements and state permitting
                    resources and priorities. It is prudent, however,
                    to look where there are not applicable air per-
                    mit requirements, to assess whether there may
                    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.
                     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.

                        1.  Any stationary source or group of sta-
                        tionary sources that emits or has the
                        potential to emit at
                        least 100 tpy of any
                        air pollutant.                 Major Source
                                                Stationary soorca is defined as any
                                                buidling, structure, fecility, or installation
                                                which emits or may emit any air pollutant
                                                that is located within a contiguous area
                                                and under common control
                                                An air poButant is defined as any air pol-
                                                lutant agent or combination of agents,
                                                including a physical, chemical, biological,
                                                radioactive substance or matter which is
                                                emitted into or otherwise enters the ambi-
                                                ent air
                                                 3.  A stationary source or group of station-
                                                 ary sources subject to the nonattainment
                                                 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 source's emission levels for VOCs
                                                 and NO*, 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 sources" if they emit or have the
                                                 potential to emit at least the levels found
                                                 in Table 4.

                                                 If yes, the facility is subject to a Title V

                                                    Table 4.
                                             Determination in  Nonattainment Areas
                        2.  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
Area Category13
Marginal or
100 tpy
50 tpy
25 tpy
10 tpy
100 tpy
70 tpy
100 tpy
50 tpy
"The nonattainment categories are based upon the severity of the area's pollution problems. The five 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 quali-
ty 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.


                                                                    Protecting Air Quality—Protecting Air Quality
operating permit. Consult with the appropri-
ate federal, state, and/or local permitting

   If no, continue to determine whether the
facility is subject to a Title V operating permit.
 b.     Is the facility subject to
   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.)
   If yes, the facility is subject to a Title V oper-
 ating permit. Consult with the appropriate fed-
 eral, 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 has promulgated MACT standards
during the first two phases of MACT standard
promulgation.) To be subject to a MACT
standard, you must be a major source or an
area source (see sidebar  for definitions).
   If yes, the facility should be permitted
   A major source is defined as any station-
   ary 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
   combination of HAPs.

   An area sorace is any stationary source
   which is not a major source bwt which
   may be subject to controls. Area sources
   represent a collection of facilities and
   emission, points for a specific geographic
   area. Most area sources are small, but the
   collective volume o£ large aumbeis of
   iacilities can be a concern in densely
   developed areas, such as •urban neighbor-
   hoods and industrial areas.  Examples of
   areas sources subject to MACT standards
   mdude chromic add anodizing, commer-
   cial sterilization facilities, decorative
   chromium electroplating, hard chromium
   electroplating, secondary lead smelting,
   arid halogenated solvent cleaners.

   HABsi are any of the 188 pollutants listed
   m Section 112(b) of CAA. (Table 2 above
   identifies the.188 HAPs.}
under CAA Title V Consult with the appro-
priate federal, state, and/or local permitting

   If no, continue to determine if the facility
is subject to a Title V operating  permit.

   d.   Is the facility subject to
       the acid rain  program
       under Title  IV of  CAA?

   If the facility, such as a fossil-fuel fired
power plant, is subject to emission reduction
requirements or limitations under the acid rain
program, it is subject to a Title V operating


Protecting Air Quality5—Protecting Air Quality
                   permit (40 CFR § 72.6). The acid rain pro-
                   gram focuses on the reduction of annual sulfur
                   dioxide and nitrogen oxides emissions.
                       If yes, the facility is subject to CAA Tide V
                   permitting. Consult with the appropriate fed-
                   eral, state, and/or local permitting authority.
                      When you consult with the appropriate
                   permitting authority, be sure to clarify whether
                   waste management units at the facility are
                   addressed by the requirements. If waste man-
                   agement units will not be addressed through
                   the permit process, we recommend that you
                   evaluate VOC emission risks.
                       If no, continue to  determine if the facility
                   is subject to 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 deter-
                    mine whether a NESHAP or MACT standard
                    covers your facility.
                      To be covered by the OSWRO standards,
                    your facility must meet all these conditions:
                      1.   Be identified as a major source of
                      HAP emissions

                      2.   Receive waste, used oil, or used sol-
                      vents from off site that contain one or
                      more HAPs.14

                      3.   Operate one of the following six
                      types of waste management or recovery
                      operations (see 40 CFR § 63.680):
                       •  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; or
   •  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, continue to Step 3. The next series
of questions will help you consider options
for conducting an air risk evaluation.
3. Conduct a risk evaluation using one of
the following options:

  a. Use IWAIR included in this guidance if
  your unit contains any of the 95 contami-
  nants that are covered in the model.

  b. Initiate a site-specific risk assessment
  for individual units. (For surface
  impoundments, a methodology is set forth
  in Preferred and Alternative Methods for
  Estimating Air Emissions from Wastewater
  Collection and Treatment, Volume II:
  Chapter  5, Emission Inventory
  Improvement Program, March  1997.) Total
  all target constituents from all applicable
  units and consider emissions from other
  sources at the facility as well.
 II.   Assessing  Risk
   The air in our atmosphere is ubiquitous
and essential for biotic life. Additionally, it acts
as a medium for the transport of airborne con-
tamination and, therefore, constitutes an expo-
sure pathway of potential concern. Models
that can predict the fate and transport of
chemical emissions in the atmosphere can
provide an important tool for evaluating and
                    "OSWRO identified approximately 100 HAPs to be covered. This HAP list is a subset of the CAA Section 112
                    list.                                               -


                                                                      Protecting Air Quality—Protecting Air Quality
protecting air quality. Included in this guid-
ance is the Industrial Waste Air Model
(IWAIR). This model 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 uncertainties.
The purpose of this section is to provide gen-
eral information  on the atmosphere, chemical
transport in the atmosphere, and evaluation of
risks associated with inhalation of chemicals so
you can understand important factors to con-
sider when performing a risk assessment for
the air pathway.
   From a risk perspective, it is unquestion-
able that humans are continuously exposed
to air and the presence of chemicals in air is
important to consider in any type of assess-
ment. If pollutants build up to high concen-
trations in a localized area, human health
may be compromised. The concentration of
chemicals in a localized area and the resulting
air pollution that may occur  in the atmos-
phere is dependent upon the quantity and
the rate of the emissions stream from a source
                     and the ability of the air to disperse the
                     chemicals. Both meteorological and geo-
                     graphic conditions in a local area will influ-
                     ence the emission rate and subsequent dis-
                     persion of a constituent. For example, the
                     meteorologic stability of the atmosphere, a
                     factor dependent on air temperature, influ-
                     ences whether the emission stream will rise
                     and mix with a larger volume of air (resulting
                     in the dilution of pollutants) or if the emis-
                     sions stream will remain close to the ground.
                     Figure 2 is a conceptual diagram of a waste
                     site showing potential paths of human expo-
                     sure through air.

                     A.     Assessing  Risks
                             Associated with
                             Inhalation of Ambient
                        In any type of risk assessment, there are
                     basic steps that are necessary for gathering and
                     evaluating data. These steps include: identifica-
                     tion of chemicals of concern, source character-
                     ization, exposure assessment, and risk charac-
                     terization. Each of these steps is described
                     below as it applies specifically to risk resulting
                           Figure 2. Conceptual Site Diagram
                               Dispersion    _ ...
 Volatilization -'•" •'•'•' "
r^O }    Partteulates

        •' v:.'.-' Deposition


Protecting Air Quality—Protecting Air Quality
                    from the inhalation of organic chemicals emit-
                    ted from WMUs to the ambient air. This
                    overview is presented to assist you in under-
                    standing conceptually the information dis-
                    cussed in the IWAIR section (Section II), since
                    many of these steps will be automatically per-
                    formed for you by the model.
                    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
                    a result of their concentrations and/or toxici-
                    ty 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.
                    Toxicity benchmarks are identified in this
                    step as well.
                     Source Characterization
                       In this step, the critical aspects of the
                     source (e.g., type of WMU, size, chemical
                     concentrations, location) are described.
                     When modeling an area source, such as those
                     included in this guidance,  the amount of a
                     given chemical that volatilizes and disperses
                     from a source is critically dependent on the
                     total surface area exposed. The source char-
                     acterization 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 fre-
                     quency in land application units and the
                     degree of aeration that occurs in a surface
                     impoundment. The overall content of the
                     waste being deposited in the WMU is also
                     important in projecting volatilization since
the nonvolatile component can, depending
on its chemical characteristics, bind volatiles
and prevent their emission to the ambient air.
Source characterization involves defining
each of these key parameters for the WMU
being modeled. The accuracy of projections
concerning volatilization of chemicals from
WMUs into ambient air is improved if more
site-specific information is used in character-
izing the source.
Exposure Assessment
    The goal of an exposure assessment is to
estimate the amount of a constituent 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 constituents concentra-
tion in air at a specified receptor location
and, 2) the second step estimates the amount
of the constituent the receptor will intake by
identifying life-style activity patterns. The
first step, the fate and transport modeling,
uses a combination of an emission and dis-
persion model to estimate the amount of
chemical that individuals residing and/or
working within the vicinity  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 num-
ber 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 movement and diffu-
sion are modeled to produce estimated air
concentrations at points of interest. This emis-
sion is illustrated in Figure 3.
   The pattern of diffusion and movement of
chemicals that volatilize  from WMUs
 depends on a number of interrelated factors.


                                                                        Protecting Air Quality—Protecting Air Quality
                            Figure 3. Emissions from a WMU
                      Emission Source
The ultimate concentration and fate of emis-
sions to the air are most significantly impact-
ed by three meteorologic conditions: atmos-
pheric stability, wind speed, and wind direc-
tion. These meteorologic factors interact to
determine the ultimate concentration  of a
pollutant in a localized area.
  Atmospheric stability: The stability of the
atmosphere is influenced by the vertical tem-
perature structure of the air above the emis-
sion source. In a stable environment, there is
little or no movement of air parcels, and,
consequently, little or no movement and mix-
ing of contaminants. In such a stable air envi-
ronment, chemicals become "trapped" and
unable to move. Conversely, in an unstable
environment there is significant mixing and
therefore greater dispersion and ultimately,
dilution  of the plume.15
  Prevailing wind patterns and their interac-
tion with land features: The nature of the
wind patterns immediately surrounding the
WMU can  significantly impact the local air
concentrations of airborne chemicals.
Prevailing wind patterns combine with topo-
graphic features such as hills and buildings to
affect the movement of the plume. Upon
release, the initial direction that emissions
will travel is the direction of the wind. The
strength of the wind will determine how
dilute the concentration of the pollutant will
be in that direction. For example, if a strong
wind is present at the time the pollutants are
released, it is likely the pollutants will rapidly
leave the source and become dispersed quick-
ly into a large volume of air.
   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 signifi-
cantly greater effects on airborne particulates)
15An example of an unstable air environment is one in which the sun shining on the earth's surface has resulted
in warmer air at the earth's 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.


Protecting Air Quality—Protecting Air Quality
                                       Figure 4. Forces That Affect Contaminant Plumes.
                     Wet Deposition
                      Dry Deposition

                                                                              4 AtSr
                     and therefore are not considered.
                        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 workers
                     located at fixed distances from the WMU, and
                     the only route of exposure considered for
                     these receptors is the inhalation of volatiles.
                     The activity patterns are used to determine the
                     intake of the constituent. Intake estimates
                     quantify the extent to which the individual is
                     exposed to  the contaminant and are a function
                     of the breathing rate, exposure concentration,
                     exposure duration, exposure frequency, expo-
                     sure averaging time (for carcinogens), and
                     body weight. Estimated exposures are present-
                     ed 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 deter-
mined during the exposure assessment phase
are combined with toxicity values to generate
risk estimates. Toxicity values used in IWAIR
include inhalation-specific cancer slope fac-
tors (CSFs) for carcinogenic effects and refer-
ence concentrations (RfCs) for noncancer
effects. These are explained in the general
risk section under the building partnerships
chapter. Using these toxicity values, risk esti-
mates are generated for carcinogenic effects
and noncancer effects. Risk estimates for car-
cinogens are summed by IWAIR.


                                                                     Protecting Air Quality—Protecting Air Quality
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. The program requires
only a limited amount of site-specific infor-
mation, including facility location, WMU
characteristics, waste characteristics, and
receptor information. A brief description of
each component follows. The IWAIR
Technical Background Document contains a
more detailed explanation of each.

1.   Emissions Model
   The emissions model uses waste character-
ization, WMU, and facility information to
estimate emissions for 95 constituents. The
emission model selected for incorporation
into  IWAIR is EPA's CHEMDAT8 model. This
model has undergone extensive review by
both EPA and industry representatives and is
publicly available 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 calcu-
lates 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 }ig/m2 - s) to obtain a unitized air concen-
tration (UAC), also called a dispersion factor,
which is measured in ]Vm3 per ug/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 loca-
tion/WMU is very time consuming and
requires extensive meteorological data and
technical expertise. Therefore IWAIR incorpo-
rates default dispersion factors developed by
ISCST3 for many separate scenarios designed
to cover a broad range of unit characteristics,
•   29 meteorological stations, chosen to
    represent the nine general climate
    regions of the continental U.S.;
•   4 unit types;
•   14 surface area sizes for landfills,
    land application units and surface
    impoundments, and 7 surface area
    sizes and 2 heights for waste piles;
•   6 receptor distances from the unit
    (25, 50, 75, 150, 500, 1000 meters)
    placed in...
•   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
   Based on the size and location of a unit,
as specified by a user, IWAIR selects an


Protecting Air Quality—Protecting Air Quality
                    appropriate dispersion factor from the
                    default dispersion 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 dis-
                    persion in relation to the two closest unit
                      Alternatively, a user may enter a site-spe-
                    cific dispersion factor developed by conduct-
                    ing 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 constituent's 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 EPA's
                    Exposure Factors Handbook (U.S. EPA, 1997)
                    and represent average exposure conditions.
                    1WAIR maintains standard health bench-
                    marks (cancer slope factors for carcinogens
                    and reference concentrations for noncarcino-
                    gens) for 95 constituents. These health
                    benchmarks are from the Integrated Risk
                    Information System (IRIS) and the Health
                    Effects Assessment Summary Tables (HEAST)
                    (U.S. EPA, 1997a, 1998). The  IWAIR uses
                    these data to perform either a  forward calcu-
                    lation to obtain risk estimates  or a backward
                    calculation to obtain protective waste con-
                    centration 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 input require-
ments are specified 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. Select
  one of two calculation methods. Use the
  forward calculation to arrive at chemical-
  specific and cumulative risk estimates if
  the user knows the concentrations of con-
  stituents in the waste. Use the backward
  calculation 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.

  b.   Identify Waste Management Unit.
  Four WMU types can be modeled: surface
  impoundments (Sis),  land application
  units (LAUs), active landfills (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 spe-
  cific 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 operating parameters that the user
  may choose, if appropriate.

   c.   Define Waste Managed. Specify con-
  stituents and concentrations in the waste if
  you choose a forward  calculation to arrive at
   chemical specific risk estimates. If you
   choose a backward calculation to estimate
   protective waste concentrations, then specify
   constituents of concern. The screen where
   this step is performed  is shown in Figure 7.


                                                                              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.
             .   V
    Calculation option
               -• v^-lfP^O
             i-i!tll*i§iiJ^--L. ^'J$
' v •:..*' w;^y.£W ~sv xv-^'^'r*".•''••  • -;v '.^ •„- ••F;,^5^;-:J>
:' «;_|^^p;»rfe^n5ris*'p;|».g.,d»|^e«;;;|^:;i
                                                        Forward Calculation to Risk
                                                      Backward Calculation to Protective
                                                      Waste Concentration
                                                          Land Application Unit(LAU)
                                                          Waste Pile (WP)
                                                          Surface Impoundment (SI)
                                                          aerated and quiescent
                                                       User Specified Emission Rates
                                                      ISCST3 Default Dispersion Factors
                                                        User-specified Dispersion Factors
                                                   Calculates ambient air concentrations for
                                                       receptor based on emission and
                                                   1. Chemical-specific Carcinogenic Risk
                                                   2. Chemical-specific Non-carcinogenic Risk
                                                   3. Total Cancer Risk
                                                 I    *  Cwforwastswatera {mg/L)
                                                 |    •  Cw for solid wastes (mg/kg)


Protecting Air Quality—Protecting Air Quality
                                        Figure 6. Screen 1, Method, Met Station. WMU.
                                                                   Sertctsd »Wooi-iA39i«ISaOonfor SKo
                                               Figure 7. Screen 2, Waste Managed.
                                 Ocic •**«»>"
                                 To F4x»v8 Charted hM««K»mw<Urtt, Select Owrtcslio


                                                                   Protecting Air Quality—Protecting Air Quality
d.   Determine Emission Bates. You can
elect to develop CHEMDAT8 emission
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 29 IWAIR meteorological sta-
tions. Data from the meteorological sta-
tions provide wind speed and temperature
information needed to develop emission
estimates. In some circumstances the user
may already have emissions information
from monitoring or a previous modeling
exercise.  As an alternative to using the
CHEMDAT8 rates, a user may 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 dispersion
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
developing the IWAIR default dispersion
data (for example, flat terrain was
assumed), you may elect to provide site-
specific dispersion factors which can be
developed by conducting independent
modeling with ISCST3 or with a different
model. Whether you use IWAIR or provide
dispersion factors from another source,
specify distance 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.

£   Calculate Ambient Air Concentra-
tion. For each receptor, the model com-
bines emission rates and dispersion data to
estimate  ambient air concentrations for all
waste constituents of concern.
  g.   Calculate Results. The model calcu-
  lates results by combining estimated ambi-
  ent air concentrations at a specified expo-
  sure point with receptor exposure factors
  and toxicity benchmarks. Presentation of
  results depends on whether you chose a
  forward 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 prevention
or treatment to reduce volatile organic com-
pound (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 denned risk level (e.g., 1 x lO^or
hazard quotient of 1) for specified receptors.
This information should be used to deter-
mine preferred characteristics for wastes
entering the unit. There are several options if
it appears that planned waste concentrations
may be too high: 1) implement pollution pre-
vention or treatment to reduce VOC concen-
trations 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 charac-
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 unacceptable risk to human
health. However, because the model can


Protecting Air Quality—Protecting Air Quality
                    accommodate only a limited amount of site-
                    specific information, it is important to under-
                    stand it's capabilities and recognize situations
                    when it may not be appropriate - when
                    another model would be a better choice.

                    •   The model provides a reasonable, conser-
                        vative representation 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 fea-
                        tures 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 calcu-
                           lation from the unit or a backward
                           calculation from the receptor point.
                        •  A user can modify health bench-
                           marks (HBNs) and target risk level,
                           when appropriate and in consulta-
                           tion with other stakeholders.

                    •   Chemicals of Concern. If waste contains
                        chemicals that (1) are not included in the
                        model and (2) have human health effects
                        and may be present in concentrations
                        sufficient to pose a risk to public health
                        via inhalation exposure, the model will
                        not fully characterize risks for that WMU
                        since these additional chemicals would
                        be excluded from consideration.
                    •  Release Mechanisms and Exposure
                        Routes. The model considers exposures
                        from breathing ambient air. It does not
  address potential risks attributable to
  paniculate 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 manage-
  ment units.  Competing mechanisms
  such as runoff,  erosion, and leaching are
  not accounted for in the model. In so
  much as these competing processes actu-
  ally occur, the model would tend to
  slightly overestimate the volatile emis-
  sions. On the other hand, one could
  interpret this situation as being represen-
  tative of WMUs that have leachate con-
  trols, such as liners, or erosion and
  runoff controls. Such controls would
  tend to inhibit these processes and result
  in more volatile emissions.
l  Waste Management Practices. The user
  specifies a number of unit-specific para-
  meters 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 accommo-
  date information concerning control
  technologies 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 may be necessary
  to generate site-specific emission rates
  and enter those into IWAIR.
I  Terrain and Meteorological Conditions. If
 a facility is located in an area of interme-
  diate or complex terrain or with unusual
  meteorological conditions, it may be nec-
  essary to either (1) generate site-specific


                                                                    Protecting Air Quality—Protecting Air Quality
   air dispersion modeling results for the
   site and enter those results into the pro-
   gram, or (2) use a site-specific risk model-
   ing approach different from IWAIR. The
   model will inform the user which of the 29
   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 facility can
  impact air dispersion modeling results and
  ultimately risk estimates. In performing air
  dispersion modeling to develop the IWAIR
  default dispersion factors, it was assumed
  that the facility was located in an area of
  simple or flat terrain. The Guideline on Air
  Quality Models (U.S. EPA, 1993) can assist
  users in determining 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
   predetermined exposure factors. The
   program cannot be  used to characterize
   risk for other possible exposure scenarios.
   For example, the model can not evaluate
   receptors that are closer to the unit than
   25 meters or those that are further from
   the unit that 1000 meters.
C.     Site-specific Risk
  IWAIR is not the only model that may be
applicable to a site. In some cases, a site-spe-
cific risk assessment may be more advanta-
geous. A site-specific approach can be tai-
lored to accommodate the individual needs of
a particular WMU. Such an approach would
rely on site-specific data and on the applica-
tion of existing fate and transport models.
Table 5 summarizes available emissions
and/or dispersion models that may be applied
in a site-specific analysis. Practical considera-
tions 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 proprietary),
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
attributes of the site in question.  However, as
with all modeling, the state authority should
be consulted prior to investing significant
resources in a site-specific analysis. The state
may have preferred models and/or may be
able to help plan the analysis.
III.  Emission  Control
A.    Controlling  Particulate
       Matter (PM)
   PM consists of airborne solid and liquid
particles. When PM is very small, it is easily
inhaled and trapped in the lungs, where it
can cause various health problems. PM also
impacts the environment by decreasing visi-
bility and harming plants  as well as trans-
porting hazardous constituents offsite. We
recommend 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 gen-
erated 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 han-
dling procedures. Developing a fugitive dust
16Fugitive emissions are defined as emissions not caught by a capture system and therefore exclude PM emitted
from exhaust stacks with control devices.


Protecting Ak Quality—Protecting Air Quality
                   Model Name
                    Toxic Screening Model
                                                                 Table 5
                                                     Source Characterization Models
 The CHEMDAT8 model allows the user to conduct source and chemi-
 cal specific emissions modeling. CHEMDAT8 is a Lotus 1-2-3
 spreadsheet that includes analytical models to estimate volatile organ-
 ic compound emissions from treatment, storage, and disposal facility
 processes under user-specified input parameters. CHEMDAT8 calcu-
 lates the fractions of waste constituents of interest that are distributed
 among pathways (partition fractions) applicable to the facility under

 Emissions modeling using CHEMDAT8 is conducted using data
 entered by the user for unit-specific parameters. The user may
 choose to override the default data and enter their estimates for these
 unit-specific parameters.  Thus, modeling emissions using CHEM-
 DAT8 can be done with a limited amount of site-specific information.

 Available at <www.epa.govAtn/chie£''softwareJitnil>, hotline at
 (919) 541 5610 for more information.
 A steady-state Gaussian plume dispersion model that can estimate
 concentration, dry deposition rates (particles only), and wet deposi-
 tion rates. Is applicable for continuous emissions , industrial source
 complexes, rural or urban areas, simple or complex terrain, transport
 distances of less than 50 km, and averaging times from hourly to
 Available at <www.epa.gov/scram.001/i>
 The COMPDEP model was developed to calculate air concentration
 and deposition fluxes, particularly in areas of complex terrain. This
 model uses standard meteorological data to produce estimates of
 annual average concentration, total annual dry deposition, and wet
 deposition flux at individual receptor sites.  COMPDEP accounts for
 pollutant deposition and terrain adjustments.
 This model was developed for and is only applicable in rural areas.
 Available at <www.epa.gov/scram.00l/>
 Performs emission rate, pool evaporation , and natural and dense gas
 dispersion calculations. TSCREEN uses simple methods, and therefore
 is primarily used for screening. Little or no modeling experience is
 required to use this  model.
                   Source: <www.epa.gov/rgytgrnj/programs/artd/toxics/arpp/etools.htm>


                                                                       Protecting Air Quality—Protecting Air Quality
control plan is an efficient way to tackle these
problems. The plan should include a descrip-
tion of all operations conducted 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 exposure to dust (see 29 CFR §
1910.1000). Check to see if the state also has
regulations or guidance concerning dust or
fugitive emission control.
   PM  emissions at waste management units
vary with the physical and chemical character-
istics 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 techniques.

    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, cover the waste with
tarps or place wastes in containers such as
double bags or drums17
   A unit may 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. 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, construct temporary roadways with
gravel or other coarse aggregate material to
reduce silt content and thus, dust generation.
In addition, consider regularly cleaning paved
roads and other travel surfaces of dust, mud,
and contaminated material.
   In land application units, the entire appli-
cation surface is often covered with a soil-
waste mix. The most critical preventive con-
trol measure, therefore, involves minimizing
contact between the application surface and
waste delivery vehicles. If possible, allow only
dedicated application vehicles on the surface,
restricting delivery vehicles to a staging or
loading area where they deposit waste into
application vehicles or holding tanks. If deliv-
ery 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
   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 to
loadout. Increasing the moisture content,
however, may not be suitable for all waste
streams, as water  could cause an adverse
"Containerizing wastes provides highly effective control of PM emissions, but, due to the large volume of many
industrial waste streams, containerizing waste may not always be feasible.


Protecting Air Quality—Protecting Air Quality
                    chemical reaction with some wastes or unac-
                    ceptably increase 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 may or may not be
                    advisable depending  on application intensity
                    and frequency, the  potential for tracking of
                    contaminated material off site, and climatic
                    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
                    may provide  little effective control, while too
                    frequent or high-intensity application may
                    increase leachate volume, straining leachate
                    collection systems and threatening ground
                    water and surface water. Addition of excess
                    water to bulk waste material or to unit sur-
                    faces also can reduce the structural integrity
                    of the landfill lifts,  increase tracking of conta-
                    minated mud off site, and worsen odor.
                    These undesirable possibilities may 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 quali-
                    ty. Consult with your state agency with
                    respect to these problems.
                       Chemical  dust suppressants are an alterna-
                    tive to water application. The suppressants
                    are detergent-like surfactants that increase
                    the total number of droplets and allow parti-
                    cles to more  easily penetrate the droplets,
                    increasing the total surface area and contact
                    potential. Adding a surfactant to a relatively
                    small quantity of water and mixing vigorous-
                    ly 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 more effectively than water.
When applied to a unit, suppressants cement
loose material into a more impervious surface
or form a surface which attracts and retains
moisture. Examples of chemical dust sup-
pressants are provided in Appendix IV . The
degree of control achieved is a function of
the application intensity and frequency and
the dilution ratio. Chemical dust suppres-
sants tend to require less frequent application
than water, reducing the potential for
leachate generation. Their efficiency varies,
depending on the same  factors as water
application, as well as spray nozzle parame-
ters, but generally falls between 60 and 90
percent reduction in fugitive dust emissions.
Suppressant costs, however, 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
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, may emit PM during scraping or
bulldozing operations to remove residual
materials. The uppermost layer of the low
permeability soils, such as compacted clay,
which may be used to line a surface
impoundment, contains the highest contami-
nant concentrations. Paniculate emissions
from this uppermost layer, therefore, are the
chief contributor to contaminant emissions.
When removing residuals from active units,
ensure that equipment scrapes only the resid-
uals, avoiding the liner below.


                                                                      Protecting Air Quality—Protecting Air Quality
    3. Wind  Erosion
   Wind erosion occurs when a dry surface is
exposed to the atmosphere. The effect is most
pronounced with bare surfaces of fine 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 in-situ soil liners tend
to form crusts as their surfaces dry. Crusted
surfaces usually have little or no erosion
potential. Examine the crust thickness and
strength during site inspections. If the crust is
more than JA inch thick and does not crum-
ble easily, then the soil probably has almost
no erosion potential.
   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 parti-
cles and reduces emissions from the exposed
surface. It can also shelter materials handling
operations to reduce entrainment 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 effec-
tiveness of wind fences or barriers for the con-
trol of windblown dust under field conditions.
Several of these studies have shown a decrease
in wind velocity, however, the degree of emis-
sions reduction varies significantly 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 fine-particle wastes are loaded
onto a waste pile, the potential for dust emis-
sions is at a maximum, as fine particles are eas-
ily disaggregated and picked up by wind. This
tends to occur when material is either 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 weathered, its potential for dust emis-
sions may be greatly reduced. This occurs
when moisture from precipitation and conden-
sation causes aggregation and cementation of
fine particles to the surface of larger particles,
and when vegetation grows on the pile, shield-
ing the surface and strengthening it with roots.
Finally, limiting height  of the pile can reduce
PM emissions, as wind velocities generally
increase with distance from the ground.

B.    VOC Emission Control
   If air modeling indicates that VOC emissions
are a concern, consider pollution prevention
and treatment options to  reduce risk. There are
several control techniques you can use. Some
are applied before the waste is placed in the
unit, reducing emissions; others contain emis-
sions that occur after waste placement; still oth-
ers process the captured emissions.

     1. Choosing a Site to  Minimize
       Airborne Emission Problems
   Careful site choice can reduce VOC  emis-
sions. Look for locations that are sheltered


Protecting Air Quality—Protecting Air Quality
                    from wind by trees or other natural features.
                    Know the direction of prevailing winds and
                    determine whether the unit would be
                    upwind from existing and expected future
                    residences, businesses, or other population
                    centers. 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 die volatiles near the point of
                    generation may obviate the need for controls
                    on your subsequent process units and may
                    facilitate recycling the recovered organics
                    back to the process.
                       The control efficiency of organic removal
                    depends on many factors, such as emissions
                    from die removal system, and the uncon-
                    trolled emissions from management units
                    before die removal device was installed.
                    Generally, overall organic removal efficiencies
                    of 98 to over 99 percent can be achieved.

                         3. Enclosure of Units
                       You may be able to control VOC emissions
                    from your landfill or waste pile by installing
                    a  flexible membrane cover, enclosing the unit
                    in a rigid structure, or using an air-supported
                    structure. Fans maintain positive pressure to
                    inflate an air-supported structure. Some of
                    the air-supported covers that have been used
                    consist of PVC-coated polyester with a
                    polyvinyl fluoride film backing. The efficien-
cy of air-supported structures depends pri-
marily on how well the structure prevents
leaks and how quickly any leaks that do
occur are detected. For effective control, the
air vented from the structure should be sent
to a control device, such as a carbon adsor-
ber. Consider worker safety issues related to
access to the interior of any flexible mem-
brane cover or other pollutant concentration
   Wind fences or barriers may 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 may 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 organic
compounds, the membrane must provide a
seal at the edge of the impoundment and rain-
water must be removed. If gas is generated
under the cover, vents and a control device
may also be needed. Emission control depends
primarily on the type of membrane, its thick-
ness, and the nature of the organic compounds
in the waste. One study tracked a membrane
cover made of 100-mil high-density polyethyl-
ene extended over a concrete ring wall that
extended above grade level around the perime-
ter of the impoundment, and covered with
backfill to anchor and seal it. Theoretical esti-
mates based on diffusion through the mem-
brane indicate control efficiencies of 50 to 95
percent. Again, consult with your state or local
air quality agency to identify the most appro-
priate emission control for your impoundment.

     4.  Treatment of Captured
   In some cases, waste will still emit some
VOCs despite waste reduction or pretreatment


                                                                      Protecting Air Quality—Protecting Air Quality
efforts. Enclosing the unit serves to prevent the
immediate escape of these VOCs to the atmos-
phere. To avoid eventually releasing VOCs
through an enclosure's ventilation system, a
treatment system is necessary. We  discuss some
of the better-known treatment methods below;
others also may 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 adsorption,
organics are selectively collected  on the sur-
face of a porous solid. Activated carbon is a
common adsorbent because of its high inter-
nal 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 con-
trolled. Control efficiencies of 97 to 99  per-
cent 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 volatile
organic compounds. Microorganisms attached
to the wetted filter material aerobically
degrade the adsorbed chemical compounds.
Biofiltration may be a highly effective and
low-cost alternative to other, more conven-
tional, air pollution control technologies such
as thermal oxidation, catalytic incineration,
condensation, carbon adsorption, and
absorption. Successful commercial biofilter
applications include treatment of gas emis-
sions from composting operations, rendering
plants, food and tobacco processing, chemical
manufacturing, foundries, and other industri-
al 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 may be useful for volatile organics
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 may 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
 18Mycock, J.C., J.D. McKenna, and L. Theodore. 1995. Handbook of Air Pollution Control Engineering and


Protecting Air Quality—Protecting Air Quality
                    organics can be accomplished in flares; thermal
                    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 surround-
                    ing 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 incinerators
                    can also achieve destruction efficiencies of at
                    least 98 percent with adequately high tempera-
                    ture, good mixing, sufficient oxygen, and an
                    adequate residence time. Catalytic incinerators
                    provide oxidation at temperatures lower than
                    those required by thermal incinerators. Design
                    considerations are important because the cata-
                    lyst may be adversely affected by high tempera-
                    tures, high concentrations of organics, fouling
                    from paniculate matter or polymers, and deac-
                    tivation by halogens or certain metals.
                       5.   Special Considerations for
                            Land Application Units
                       Since spraying wastes increases contact
                    between waste and air, promoting VOC emis-
                    sions, you may want to choose another appli-
                    cation method, such as subsurface injection,
                    if the waste contains volatile organics. During
                    subsurface injection, waste is supplied to the
                    injection unit directly from a remote holding
                    tank and injected approximately 6 inches
                    into the soil; hence, the waste is not exposed
                    to the atmosphere. In addition, consider pre-
                    treating the waste to remove the organics
                    before placing it in the land application unit.


                                                                  Protecting Air Quality—Protecting Air Quality
             Protecting Air Quality Action Items
Consider the following issues when evaluating and controlling air emissions from nonhaz-
ardous industrial waste management units:

Q     Understand air pollution laws and regulations, and determine whether and how they
       apply to a unit.

Q     Evaluate waste management units to identify possible sources of volatile organic

D     Work with your state agency to evaluate and implement appropriate emission control
       techniques, as necessary.


Protecting Air Quality—Protecting Air Quality
         American Conference of Governmental Industrial Hygienists.  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.

         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

         National Ambient Air Quality Standards for Paniculate 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. 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. 1997.  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. 1996.  Test Methods for Evaluating Solid Waste Physical/chemical Methods—SW846. Third

         U.S. EPA. 1995.  Survey of Control Technologies for Low Concentration Organic Vapor Gas Streams.

         U.S. EPA. 1995.  User's Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume I.


                                                                 Protecting Air Quality—Protecting Air Quality
                                Resources (cont)
U.S. EPA.  1995. User's Guide for the Industrial Source Complex (ISC3) Dispersion Models: Volume II-
Description of Model Algorithms.  EPA454/B-95-003b.

U.S. EPA.  1994. Air Emissions Models for Waste and Wastewater. EPA453/R-94-080A.

U.S. EPA.  1994. Handbook: Control Techniques for Fugitive VOC Emissions from Chemical Process
Facilities. EPA625-R-93-005.

U.S. EPA.  1994. Toxic Modeling System Short-Term (TOXST) User's Guide: Volume I. EPA454/R-94-

U.S. EPA.  1992. Control of Air Emissions from Superfund Sites. EPA625-R-92-012.

U.S. EPA.  1992. Protocol for Determining the Best Performing Model.  EPA454/R-92-025.

U.S. EPA.  1992. Seminar Publication: Organic Air Emissions from Waste Management Facilities.

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.

U.S. EPA.  1988. Compilation of Air Pollution Emission Factors.  AP-42.

Viessman, W, and M. Hammer. 1985. Water Supply and Pollution Control.



Protecting Surface Water

       Chapter 6
Protecting Surface Water


I, Federal Surface-Water Protection Programs    6-2

II.  Overview of Storm-Water Protection Systems 6-4

III. Best Management Practices for Waste Managment Units    6-5
    A. Baseline BMPs    6-6
    B. Activity-Specific BMPs   6-7
    C. Site-Specific BMPs   '•  6-8
          1.   Flow Diversion Practices 6-8
              a.  Storm-water Conveyances (Channels, Gutters, Drains, and Sewers)   6-8
              b.  Diversion Dikes   '•  6-8
          2.   Fjcposure Minimization Practices     6-9
              a.  Curbing and Diking    6-9
              b.  Covering  6-9
          3.   Sediment and Erosion Prevention Practices    ..6-10
              a.  Vegetation    •   6-10
              b.  Interceptor Dikes and Swales  6-11
              c.  Pipe Slope Drains f   6-11
              d. Silt Fences,  Straw Bales, and Brush Barriers  ..6-11
              e.  Storm Drain Inlet Protection  6-12
              f.  Collection and Sedimentation Basins   '   ..6-13
              g.  Check Dams    :   ...6-14
              h. Terraces and Benches   6-14
              i.  Outlet Protection 6-14

          4.   Infiltration Practices   6-15
              a. Vegetated Filter Strips and Grassed Swales 6-15
              b. Infiltration Trenches  6-15

          5.   Other Prevention Practices   6-15
              a. Preventive Monitoring  6-16
              b. Dust Control   ,   6-16
              c. Vehicle Washing    •   6-17
          6.   Mitigation Practices •   6-17
              a.  Discharges to Wetlands    ;   6-17

 IV  Methods of Calculating Run-on and Run-off Rates    i   6-17

 Action Items for Protecting Surface Water  6-20

 Resources  r   "-^l


                                   Table of Contents
    Figure 1. BMP Identification and Selection Flow Chart   6-6
    Figure 2. Coverings 6-9
    Figure 3. Silt Fence    6-12
    Figure 4. Straw Bale    6-12
    Figure 5. Storm Drain Inlet Protection  6-13
    Figure 6. Collection and Sedimentation Basins   6-14
    Figure 7. Outlet Protection 6-15
    Figure 8. Infiltration Trench   6-16
    Figure 9. Typical Intensity-Duration-Frequency Curves   6-19



                                                             Protecting Surface Water—Protecting Surface Water
                    Protecting  Surface Water

       Protect surface waters by limiting the discharge of pollutants into
    the waters of the United States. Guard against inappropriate dis-
    charges 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 regulations,
    implementing available storm water controls, and identifying best
    management practices (BMPs) to control storm water.
            Over 70 percent of the Earth's sur-
            face is water. Of all the Earth's
            water, 97 percent is found in the
            oceans and seas, while three per-
            cent is fresh water. This fresh
water is found in glaciers, lakes, ground water,
and rivers. Water offers many valuable uses to
individuals and communities. Water is neces-
sary for recreational needs, drinking water
demands, fishing, commerce, agriculture, and
the overall quality of life.
  This chapter will help address the
  following questions:     .
  • What are the objectives of run-on and
  run-off control systems?
  • What should be considered in designing
  surface-water protection systems?
  • What are the appropriate BMPs to
  address pollutant sources?
  • What are some of the engineering and
  physical mechanisms available to control
  storm water?
  With water being such a valuable com-
modity, the protection of our surface waters
should be everyone's goal. This goal can be
achieved by everyone focusing on improving
the quality of our surface waters.
Improvements in the quality of our surface
waters can be achieved by the continued pro-
tection against the discharge of pollutants.
Pollutants associated with process waste-
waters and storm waters need to be con-
  This chapter summarizes the existing fed-
eral surface-water protection programs. The
majority of this chapter then discusses meth-
ods that can be used to eliminate pollutant
discharges into surface waters associated with
storm-water management. Controlling storm-
water run-on and run-off from waste manage-
ment units minimizes contamination of sur-
face water. Use best management practices
(BMPs) in conjunction with engineering and
physical mechanisms to control storm water
and reduce or eliminate contaminant releases
to the environment.


Protecting Surface Water—Protecting Surface Water
                    I.     Federal  Surface-

                           Water Protection

                      The federal Clean Water Act (CWA) gov-
                    erns the discharge of all pollutants into waters
                    of the United States, such as lakes, rivers,
                    streams, wetlands, ponds, or lagoons. It does
                    so primarily through a permitting process
                    known as the National Pollutant Discharge
                    Elimination System (NPDES).  All entities that
                    discharge pollutants of any kind into waters of
                    the United States must have an NPDES per-
                    mit. Permits are issued for three types of
                    wastewaters: process wastewater, nonprocess
                    wastewater, and storm water. Permits typically
                    set forth specific "effluent limitations" relating
                    to the type of discharge. For process waste-
                    waters, the permit incorporates the more
                    stringent of industry-specific,  technology-
                    based limitations, which can be found at 40
                    CFR Parts 405-471, or water quality-based
                    effluent limits (WQBELs).1 NPDES permits
                    also set forth monitoring and  reporting
                    requirements. Some waste management units,
                    such as surface impoundments, may receive
                    an NPDES permit to discharge wastewaters
                    directly to surface waters. Other units may
                    need an NPDES permit only for storm-water
                    discharges. For industrial facilities that dis-
                    charge wastewaters to Publicly Owned
                    Treatment Works (POTW) through domestic
                    sewer lines, pretreatment of the wastewater
                    may be required. Under the National
                    Pretreatment Program, EPA, the state, and the
                    local regulatory agency establish discharge
                    limits to reduce the level of pollutants dis-
                    charged by industry into municipal sewer sys-
                    tems. These limits control pollutant levels
                    reaching a POTW, improving  the quality of
                    the effluent and sludges produced by the
                    POTW. Protecting the POTW and improving
                    effluent and sludge quality  significantly
                    increases the opportunity for  beneficial reuse
of these end products. A fact sheet and fre-
quently asked questions on industrial pre-
treatment is included in the Appendix I for
this chapter, and are available on the Office of
Wastewater Management's web page at
  As mentioned previously, some units may
be required to obtain an NPDES permit for
storm-water discharges. EPA has defined 11
categories under the definition of "storm
water associated with industrial activity" (40
CFR §122.26(b)(14)) that require an NPDES
storm-water permit for discharges to navigable
waters. These 11 categories  consist of: (1)
facilities subject to storm-water effluent limita-
tions guidelines, new source performance
standards, or toxic pollutant effluent standards
under 40 CFR Part 129 (manufacturers of 6
specific pesticides); (2) "heavy" manufacturing
facilities; (3) mining and oil and gas opera-
tions with "contaminated" storm-water dis-
charges; (4) hazardous waste treatment, stor-
age, or disposal facilities; (5) landfills, land
application sites, and open dumps; (6) recy-
cling facilities; (7) steam electric 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 and land application units
would fall under category 5.
   Most surface impoundments that are
addressed by this guidance are part of an indus-
trial wastewater treatment process that results in
an NPDES-permitted discharge into surface
waters. The NPDES permit only sets pollution
limits for the final discharge  of treated waste-
water. It does not establish any regulatory
requirements for design or operation of surface
impoundments that are part of the treatment
process such as liners and ground-water moni-
toring. Individual state environmental agencies,
under their own statutory authorities, may
                    ^-Facilities that discharge wastewaters to publicly-owned treatment works (POTWs) may be subject to pretreatment
                    requirements found in 40 CFR Part 403.


                                                                   Protecting Surface Water—Protecting Surface Water
impose such requirements on surface
impoundment design and operation.
   To provide flexibility for the regulated
community in acquiring storm-water dis-
charge permits, EPA has two NPDES permit
application options: individual permits and
general permits.2 Applications for individual
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 specific para-
meters. General permit applications usually
involve the submission of a Notice of Intent
(NOI) that includes only general information,
not industry-specific or pollutant-specific
BMPs, and typically do not require collection
of monitoring data. NPDES general storm-
water permits require the development and
implementation of storm-water pollution pre-
vention plans and BMPs to limit pollutants in
storm-water discharges. EPA has issued the
Multi-Sector General Permit (60 Federal
Register 50803; September 29, 1995) which
covers 29 different industry  sectors. The
Agency reviewed, on a sector-by-sector basis,
information concerning industrial activities,
BMPs, materials stored outdoors, and end-of-
pipe storm-water sampling data. Based on
this review, EPA identified pollutants of con-
cern in each industry sector, sources of these
pollutants, and BMPs used to control them.
The Multi-Sector General Permit requires the
submission of an NOI, development and
implementation of a site-specific pollution
prevention plan as the basic storm-water con-
trol strategy for each industry sector.
   Sometimes it may be appropriate to "pre-
treat" the storm water before discharging it
into municipal separate storm sewer systems.
Using proven pollution control technologies,
practices that promote reuse and recycling of
material, and wastewater treatment, pollu-
tants from storm water can be reduced or
eliminated before it is discharged. NPDES
permits for "storm-water discharges associat-
ed with industrial activity" (as previously
defined) are issued by EPA or states with
NPDES permitting authority. If located in a
state with NPDES authority, contact the state
directly to determine the requirements for
storm water 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
fact sheets and frequently asked questions on
the NPDES permit program. These facts
sheets can be found at
<www.epa.gov/owm/npdes.htm>, and are
included in the Appendix III for this chapter .
If a state does not have NPDES permitting
authority, follow any state requirements for
storm-water discharges and contact EPA to
determine applicable federal requirements for
storm-water discharges.
  If a waste management unit is subject to
federal or state storm-water discharge
requirements, use this chapter as an aid in
complying with applicable storm-water
  Is a permit needed?            :
  To answer questions about whether or not
 ' a-facility needs to seekpermit coverage, or
  to determine whether a particular program
 ; is administered by EPA or a state agency,
  contact the state or EPA regional storm
  water official listed in the Appendix II:
  Currently, 42 states and the U.S. Virgin
  Islands have federally approved state
  NPDES permit programs. The following
  8 states do not have  final EPA approval:
 : Alaska, Arizona, Idaho, Maine,
 /Massachusetts, New  Hampshire^ New
  Mexico and Texas.
initially a group application procedure was available for facilities with similar activities to jointly submit a sin-
gle application for permit coverage. A multi-sector general permit was then developed based upon information
provided in the group applications. The group application option was only for use in the initial stages of the
program and is no longer available.


Protecting Surface Water—Protecting Surface Water
                   discharge requirements and maintaining
                   appropriate surface-water controls. If a unit is
                   not subject to federal or state storm-water dis-
                   charge requirements, use this information to
                   proactively develop surface-water protection
                    II.    Overview  of
                      Protecting surface water entails preventing
                   storm-water contamination during both unit
                   construction and the operational life of the
                   waste management unit. The primary run-off
                   contaminant during construction is sediment
                   eroded from exposed soil surfaces. Temporary
                   sediment and erosion control measures, such
                   as silt fences around construction perimeters,
                   straw bales around storm-water inlets, and
                   seeding or straw covering of exposed slopes,
                   are typically used to limit and manage erosion.
                   States or localities often require the use of sed-
                   iment and erosion controls at any construction
                   site disturbing greater than a certain number
                   of acres, and may have additional require-
                   ments in especially sensitive watersheds.
                   Consult with the state and local regulatory
                   agency to determine sediment and erosion
                   control requirements for construction.
                      Once a waste management unit has been
                   constructed, permanent run-on and run-off
                   controls are necessary to protect surface water.
                   Run-on controls are designed to prevent storm
                   water from entering active areas of units. If
                   run-on is not prevented from entering active
                   areas, it may seep into the waste and increase
                   the amount of leachate  that must be managed.
                   It can also deposit contaminants from nearby
                   sites, such as pesticide from adjoining farms,
further burdening treatment systems.
Excessive run-on may also damage earthen
containment systems, such as covers and
berms. Run-on that contacts the waste may
carry contaminants into receiving waters
through surface-water run-off or into ground
  What is "run-on"?

  Run-on is a term used to refer to water
  from outside a waste management unit that
  flows toward the unit. Run-on encompass-
  es 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.

  Why are run-on controls necessary?

  Run-on controls are designed to prevent
  (1) contamination of storm water,  (2) ero-
  sion that may damage the physical struc-
  ture of units, (3) the surface discharge of
  waste constituents, (4) the creation of
  leachate, and (5) already contaminated sur-
  face water from entering the unit.
  What is "run-off1?

  Run-off is a term used to refer to water or
  leachate that drains or flows over land from
  any part of a waste management unit. Run-
  off can be created by rainfall, or the melt-
  ing of snow and ice.

  What is the purpose of a "run-off" control

  Run-off control systems are designed to
  collect and control at least the water flow
  resulting  from a storm event of a specified
  duration, such as a 24-hour, 25 year storm


                                                              Protecting Surface Water—Protecting Surface Water
water through infiltration. The Multi-Sector
General Permit does not authorize discharges
of leachate, which includes storm water
which contacts waste. The discharge of
leachate would be regulated under either an
individually drafted NPDES permit with site-
specific discharge limitations, or an alterna-
tive NPDES general permit if one is  available.
Divert run-on by taking advantage of natural
contours or by constructing ditches  or berms
designed to intercept and drain storm water.
Run-on diversion systems should be designed
to handle the peak discharge of a design
storm event, such as a 25-year storm. (See
Section IV for more information about design
storm events.)
  Run-off controls channel, divert, and con-
vey storm water to treatment facilities, if
appropriate, and to intended discharge
points.  Manage run-off from a waste manage-
ment unit as a potentially contaminated
material. Due to the potential for contamina-
tion, manage contact run-off from active areas
of a landfill or waste pile as  leachate. Design
the leachate collection and removal systems
to handle such run-off, as well as any
leachate generated. Segregate noncontact run-
off to reduce the volume that may need to be
handled as leachate. Design surface impound-
ments with sufficient freeboard and adequate
capacity to accommodate not only waste but
also precipitation. For land application sites,
run-off from the application site may adverse-
ly affect nearby surface waters.
III.  Best
       Practices for
  Evaluation of BMPs should be considered in
both the design and operation of a waste man-
agement unit. Before identifying and imple-
menting BMPs, assess potential sources of
storm-water contamination. Two of the most
common sources of contamination from waste
management units are erosion and sediment
discharges caused by storm events. To conduct
a thorough assessment, create a map of the
waste management unit area, review operating
practices, and consider the design of the waste
management unit. Designing a surface-water
management system requires a knowledge of
local precipitation patterns, surrounding topo-
graphic features, and geologic conditions. After
a unit is in place, consider sampling run-off to
ascertain the quantity and concentration of
pollutants currently being discharged.  (Refer to
the chapter on monitoring performance for
more information.) Collecting this information
may help select the most appropriate BMPs to
prevent or control pollutant discharges. Figure
1 illustrates the process of identifying and
selecting the most appropriate BMPs.
  After assessing the potential and existing
sources of storm water contamination, the
                                             What are BMPs?

                                             BMPs are measures used to reduce or
                                             eliminate contaminate releases to the envi-
                                             ronment. They can take the form of a
                                             process, activity, or physical structure.


Protecting Surface Water—Protecting Surface Water
                    Figure 1. BMP Identification and Selection Flow Chart
                                      Assessment Phase
                      Develop 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 monitoring performance chapter)
                                   BMP Identification Phase
                      Operational BMPs
                      Source control BMPs
                      Erosion and sediment control BMPs
                      Treatment BMPs
                      Innovative BMPs
                                     Implementation Phase
                      Implement BMPs
                      Train employess
                                  Evaluation/Monitoring Phase
                      Conduct semiannual inspection/BMP evaluation
                         (see operating the waste management system chapter)
                      Conduct recordkeeping
                      Monitor surface water if appropriate
                      Review and revise plan
                    Adapted from U.S. EPA. 1992. Storm Water Management
                    for Industrial Activities: Developing Pollution Prevention
                    Plans and Best Management Practices. EPA832-R-92-006.
                    next step is to select appropriate BMPs to
                    address these pollutant contamination
                    sources. BMPs fall into three categories: base-
                    line, activity-specific, and site-specific.
                    A.     Baseline BMPs
                       These practices are, for the most part,
                    inexpensive and relatively simple. They are
           geared toward preventing situa-
           tions that could lead to surface-
           water contamination before they
           occur. Many industrial facilities
           already have these measures in
           place for product loss preven-
           tion, accident and fire preven-
           tion, worker health and safety, or
           compliance with other regula-
           tions. (See the chapter on operat-
           ing the waste management sys-
           tem.) Baseline BMPs include the
           following measures.
              Good housekeeping. A clean
           and orderly work environment is
           an effective first step toward pre-
           venting contamination of run-on
           and run-off. Inventory materials
           effectively and, if appropriate,
           store them safely in areas pro-
           tected from precipitation and
           other water.
              Preventive maintenance.
           Expand existing facility mainte-
           nance programs to include
           inspection,  upkeep, and repair or
           replacement of surface-water
           protection systems.
             Visual inspections. Conduct
           inspections of surface-water pro-
           tection systems and waste man-
           agement unit areas to discover
           potential problems and identify
           necessary changes. Areas to pay
           particularly close attention to
include previous spill locations; material stor-
age, handling, and transfer areas; and waste
storage, treatment, and disposal areas.
Promptly rectify any situations, such as leaks
or spills, that could lead to surface-water con-
   Spill prevention and response. Establish
standard general operating practices for safe-
ty and spill prevention to reduce accidental


                                                                   Protecting Surface Water—Protecting Surface Water
releases that could contaminate run-on and
run-off. Devise spill response plans to pre-
vent any accidental releases from reaching
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
protection measures. For more information
on employee training and record  keeping,
consult the chapter on operating the waste
management system.
B.     Activity-Specific BMPs
   After planning for baseline BMPs, consider
planning for activity-specific BMPs. In the
BMP manual for industrial facilities, Storm
Water Management for Industrial Activities:
Developing Pollution Prevention Plans and Best
Management Practices (EPA832-R-92-006),
EPA developed activity-specific BMPs for nine
industrial activities, including waste manage-
ment. The waste management BMPs are sum-
marized in this section. Like baseline BMPs,
these are often procedural rather than struc-
tural measures and, therefore, are often inex-
pensive and easy to implement.
Prevent waste leaks and dust emissions due to
vehicular travel. To prevent leaks, ensure that
trucks moving waste into and around a unit
have baffles (if they carry liquid waste) or
sealed gates, spill guards, or tarpaulin covers (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 the chapter on operating
the waste management system. Please be aware
that washwater from vehicle and equipment
cleaning is considered to be "process waste-
waters," and is not eligible for discharge under
EPA's Multi-Sector General Permit for industrial
storm water discharges. Such discharges would
require coverage under either an individually
drafted, site-specific NPDES permit, or an alter-
native NPDES general permit if one is available.
For land application, choose appropriate slopes.
Minimize run-off by designing a site with slopes
less than six percent. Moderate slopes help
reduce storm-water run-off velocity, which
encourages sedimentation and infiltration, and
reduces erosion.  Storm-water discharges  from
land application units are also regulated under
the Multi-Sector General Permit.
C.     Site-Specific BMPs
   In addition to baseline and activity-specific
BMPs, consider site-specific BMPs, which are
more advanced measures tailored to specific
pollutant sources at a particular waste man-
agement unit. These site-specific BMPs are
grouped into seven areas—flow diversion,
exposure minimization, sediment and erosion
prevention, infiltration, mitigation, wetlands,
and other prevention—for discussion below.
With many of the surface-water protection
techniques described in this section, it is
important to design for an appropriate storm
event. Generally, structures that control run-
on and run-off should be designed for the
discharge of a 24-hour, 25-year storm event.3
  BMP Maintenance

  Maintain these BMPs to ensure adequate
  surface-water protection. Maintenance is
  important because storms may damage
  surface-water protection systems, such as
  storage basin embarkments or spillways.
  Run-off may also cause sediments to settle
  in storage basins or ditches and carry float-
  ables-r-tree branches, lumber, leaves, and
  litter—to the basin. Facilties may need to
  repair storm-water controls and periodical-
  ly remove sediment and floatables.
^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 may not occur in
a given 25-year period, or may occur more than once during a single year.


Protecting Surface Water—Protecting Surface-Water
                     When selecting and designing surface-water
                   protection systems, consult state, regional, and
                   local watershed management organizations.
                   Some of these organizations maintain manage-
                   ment plans devised at the overall watershed
                   level that address storm-water control. They
                   may be able to offer guidance in developing
                   surface-water protection systems for optimal
                   coordination with others in the watershed. As
                   a general guide, once a BMP has been imple-
                   mented, evaluate the effectiveness of the select-
                   ed BMPs from time to time.

                   1.   Flow Diversion Practices
                     These measures are used to protect surface
                   water in two ways. First, they channel storm
                   water away from waste management units to
                   minimize contact of water with waste.
                   Second, they carry polluted or potentially
                   polluted materials to treatment facilities.

                     a.    Storm-Water Conveyances
                           (Channels, Gutters, Drains,
                           and Sewers)
                     Storm-water conveyances, such as chan-
                   nels,  gutters, drains, and sewers, may prevent
                   storm-water run-on from entering a waste
                   management unit or run-off from leaving a
                   unit untreated. Some run-on and run-off con-
                   veyances collect storm water and route it
                   around waste containment areas to prevent
                   contact with the waste, which might other-
                   wise contaminate storm water with pollu-
                   tants. Other conveyances collect water that
                   may have already come into contact 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 applica-
                   tion units). Conveyances should not mix the
                   stream of storm water diverted around the
                   unit with that of water that may have contact-
                   ed waste. Remember, storm water that con-
                   tacts  waste is considered leachate and can
  Conveyances can:

  Direct storm-water flows around industri-
  al areas, prevent temporary flooding,
  require little maintenance, and provide
  long-term control of storm-water flows.

  Keep in mind:

  Conveyances require routing through sta-
  bilized structures to minimize erosion.
  They also may increase flow rates, may be
  impractical if there are space limitations,
  and may not be economical.
only be discharged in accordance with an
NPDES permit other than the Multi-Sector
General Permit.

   Storm-water conveyances may 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. Design storm-water con-
veyances with capacity to accept the estimat-
ed storm-water flow associated with the
selected design storm event. Section IV below
discusses methods for determining  these
  b.    Diversion Dikes
   Diversion dikes, often made with compact-
ed soil, direct run-on away from a waste  ,
management unit. Dikes usually are built
uphill  from a unit and work with a storm-
water conveyance to divert the water from the
unit. To minimize the potential for erosion,
diversion dikes are often constructed to redi-
rect run-off at a shallow slope to slow its
velocity. A similar means of flow diversion is
grading a site to keep storm water away from
waste handling areas, instead of or in


                                                                   Protecting Surface Water—Protecting Surface Water
  Diversion dikes can:

  Efectively limit storm-water flows over,;
  industrial site areas; be installed at any-
  time, be economical temporary structure
  when built from soil onsite, and be con-
  verted from temporary to permanent at
  .any time:        ;                  ^

  Ifeepitimind:                ^

  Diversion dikes are not suitable for large :
  drainage areas unless there is a gentle -:::
  slope and may require maintenance after
  heavyrainsJ-   *•;;  -I:';:';'"    -."'...'  .'.''•:
addition to using diversion dikes to redirect
water that would otherwise flow into these
areas. In planning for the installation of
dikes, consider the slope of the drainage area,
the height of the dike, the size of the flow it
will need to divert, and the type of con-
veyance that will be used with the dike.

2.   Exposure Minimization
   These measures, like flow diversion prac-
tices, reduce contact of water with waste.
They often are small structures immediately
surrounding a higher risk area, while flow
diversion practices may operate on the scale
of an entire waste management unit.

  a.    Curbing and Diking
   These are raised borders enclosing areas
where liquid spills may 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.
 b.     Covering
   Protect surface water by erecting a roof,
 tarpaulin, or other permanent or temporary
 covering (see Figure 2) over areas where
 sources of surface-water contamination may
 be located. Such areas could include the
 active area of a landfill, transfer locations, and
 stockpiles of daily cover. Combining covering
 with other measures, such as curbing, can
 prevent precipitation from falling directly on
 materials and simultaneously prevent water
 originating elsewhere from running on to the

   If using temporary coverings, ensure that
 sufficient weight is attached to prevent wind
 from moving the cover, and repair or replace
 the cover material if holes or leaks develop.
            Figure 2. Coverings
Roof, overhang, or other permanent structure
Tarp or other permanent structure

From U.S. EPA. 1992. Storm Water Management for
Industrial Activities: Developing Pollution Prevention Plans
and Best Management Practices.  EPA832-R-92-006.


   Protecting Surface Water—Protecting Surface Water
                       3.  Sediment and Erosion
                           Prevention Practices
                         These 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 sediment. Erosion
                       and sedimentation can threaten aquatic life,
                       increase treatment costs for downstream
                       water treatment plants, and impede recre-
                       ational and navigational uses of waterways.
                       Erosion and sedimentation are of particular
                       concern at waste management units because
                       the sediment may be contaminated with
                       waste constituents and because erosion may
                       undercut or otherwise weaken waste contain-
                       ment structures. The following measures can
                       help limit erosion and sedimentation.

                         a.    Vegetation
                          Reduce erosion and sedimentation by
                       ensuring that areas where water is  likely to
                       flow are vegetated. Vegetation slows erosion
                       and sedimentation by shielding soil surfaces
                       from rainfall impacts, improving soil's water
                       storage capacity, holding soil in place, slow-
                       ing run-off, and enabling sediment to  drop
                       out. One means of providing vegetation is to
                       preserve natural growth. This is achieved by
                       managing construction of the unit to mini-
                       mize  disturbance of surrounding plants. If it
                       is not possible to leave all areas surrounding
                       a unit undisturbed, preserve strips of existing
                       vegetation as buffer zones in strategically cho-
                       sen areas of the site where erosion and sedi-
                       ment control is most needed, such as  on
                       steep slopes and  along stream banks. If it is
                       not possible to leave sufficient buffer zones of
                       existing vegetation, 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 cornplete. 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, tem-
porary roadbanks,  and dikes. Local regula-
tions may require temporary seeding of areas
that would otherwise remain exposed greater
than a certain length of time. Consult local
officials to determine whether such require-
ments apply. Seeding may not be feasible for
quickly establishing cover in arid climates or
during nongrowing seasons in other climates.
Sod, although more expensive, may be more
tolerant of these conditions than is seed and
may establish a denser grass cover  more
quickly. Compost can also be used effectively
to establish vegetation on slopes.
   Three other practices are often considered
along with vegetative measures. First, stream-
bank stabilization is the reinforcement of
stream banks with  stones, concrete  or asphalt,
logs, or gabions—  structures formed from
crushed rock encased in wire mesh.
Stabilization is appropriate where stream flow
may be increased due to construction or other
unit activities and where vegetative  measures
are not practical. Second, mulching, compost,
matting, and netting cover surfaces  that are
steep, arid, or otherwise unsuitable for plant-
ing. These methods also can work in conjunc-
tion with planting  to secure and protect seeds.
Mattings are sheets of mulch that are more sta-
ble 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


                                                                  Protecting Surface Water—Protecting Surface Water
birds, and hold seeds and soil in place. Third,
chemical stabilization—also known as chemi-
cal mulch, soil binder, or soil palliative—
involves spraying vinyl, asphalt, or rubber
onto soil surfaces to hold the soil in place and
protect against erosion. Erosion and sediment
control is immediate upon spraying and does
not depend on climate or season. Apply stabi-
lizer according to manufacturer's instructions
to ensure that water quality is not affected, and
avoid coating a large area with a thick layer of
stabilizer, which would create an impervious
surface and speed run-off to downgradient
Interceptor Dikes and
   Dikes, or ridges of compacted soil, and
swales, excavated depressions in which 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
grade it so  that predicted flows will not dam-
age vegetation.
  c.    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. Ensure
that pipes are of adequate size to accommo-
date the design storm event and are kept
clear of clogs.

  d.   Silt Fences,  Straw Bales,
       and Brush Barriers
   Silt fences (see Figure 3) and straw bales
(see Figure 4) are temporary measures
designed to capture sediment that has already
eroded and to reduce the velocity of storm
water. Silt fences and straw bales should not
be considered permanent measures. They
could be  used, for example, during construc-
tion of a waste management unit or on a final
cover before permanent grass growth is estab-
lished.  Silt fences consist of geotextile fabric
supported by wooden posts.  These fences
slow the flow of water and retain sediment as
water filters through the geotextile fabric. If
properly installed, straw bales perform a simi-
lar function. Straw bales should be placed end
to end  (with no gaps in between) in a shallow,
excavated trench and staked  into place. Silt
fences and straw bales limit sediment entering
                                         Silt fences, straw bales, and brush barriers

                                         Prevent downstream damage froHLsedi-
                                         ment deposits and inexpensively ^prevent
                                         eroded materials from reaching'surface
                                         waters     .••:.,.

                                         Keep to mind:

                                         These measures are not aproriate for
                                         streams or; large swales and pose a risk
                                         of washouts if improperly installed.


Protecting Surface Water—Protecting Surface Water
                                Figure 3. Silt Fence
                      Extension of fabric and wire
                      into the trench
                     Bottom: Perspective of silt fence. Top: Cross-
                     section detail of base of silt fence.
                     From U.S. EPA. 1992. Storm Water Management
                     for Industrial Activities: Developing Pollution
                     Prevention Plans and Best Management
                     Practices.  EPA832-R-006.
                                Figure 4. Straw Bale
                     From U.S. EPA. 1992. Storm Water Management
                     for Industrial Activities: Developing Pollution
                     Prevention Plans and Best Management
                     Practices. EPA832-R-006.
receiving waters. Both measures require fre-
quent inspection and maintenance, including
checking for channels eroded beneath the
fence or bales, removing accumulated sedi-
ment, and replacing damaged or deteriorated
   Brush barriers work like silt fences and
straw bales but are constructed of readily avail-
able 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. Brush bar-
riers are inexpensive due to their reuse of mate-
rial 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 may be possible to leave a former
brush barrier in place and allow it to biode-
grade, rather than remove it.

  e.    Storm Drain Inlet
   Filtering measures placed around any inlet
or drain to trap sediment are known as inlet
protection (see Figure 5). These measures pre-
vent 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 drainage
systems also serves to prevent clogging, loss of
capacity, and other problems associated with
siltation of drainage structures. Inlet protection
methods include sod, excavated areas for set-
tlement of sediment, straw bales or filter fence,
and gravel or stone with wire mesh. These
measures are appropriate for inlets draining
small areas where soil will be disturbed. Some
jurisdictions require installation of these mea-
sures before disturbance of more than a certain
acreage of land begins.  Clean accumulated
sediment from inlet protection material fre-
quently to ensure continued operation.


                                                                    Protecting Surface Water—Protecting Surface Water
                Figure 5. Storm Drain Inlet Protection
                                     Excavated Gravel Inlet Protection
         Sod Inlet Protection
           <— Filter FaDric
      Filter Fabric Inlet Protection
From U.S. EPA. 1992. Storm Water Management for Industrial Activities:
Developing Pollution Prevention Plans and Best Management Practices.
   /.     Collection and
         Sedimentation Basins
   A collection or sedimentation basin (see
 Figure 6) is an area that retains run-off long
 enough to allow most of the sediment to settle
 out and accumulate on the bottom of the
 basin. Since many pollutants are attached to
 suspended solids, some other pollutants also
 may settle out in the basin with the sediment.
 The quantity of sediment removed will depend
 on basin volume, inlet and outlet configura-
 tion, basin depth and shape,  and retention
 time. Basins should be periodically dredged to
 remove the accumulated sediment and regular-
 ly maintained to minimize growth of aquatic
 plants that can reduce their effectiveness. All
 dredged materials, whether they are disposed
 of or reused, should be managed appropriately.
   Basins also may present a safety hazard.
 Fences or other measures to prevent  unwant-
 ed public access to the basins and their asso-
                  ciated inlet and outlet     '
                  structures are prudent
                  safety precautions.

                     In designing collection
                  or sedimentation basins (a
                  form of surface impound-
                  ment), consider storm-
                  water flow, sediment and
                  pollutant loadings, and
                  the characteristics of
                  expected pollutants. In
                  the case  of certain pollu-
                  tants, it may be appropri-
                  ate 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 sediment. Poor
                  implementation of base-
                  line and  activity-specific
BMPs may result in high sediment and pollu-
tant loads, leading to unusually frequent
dredging of settled materials. For this reason,
when operating sedimentation basins, ensure
that baseline and activity-specific BMPs are
first implemented to the fullest extent practi-
cable. Construction of these basins should be
                                     Block and Gravel Inlet Protection
   Sedimentation basins cam

   Protect downstream areas against clogging
   or damage, and contain smaller sediment
   particles thanlsediment traps can due to
   theirfonger detention time.         .''•',

   Keep in mind:

   Sedimentation basins are generally not
   suitable for. large areas, require regular
   maintenance arid cleaning, and will not
   remove very fine silts and clays unless
   used with other measures


Protecting Surface Water—Protecting Surface Water
                                     Figure 6.
                      Collection and Sedimentation Basins
                       Deal* ml
                                      Plan View
                                       Minimi storige
                        suras* and
                        Fenuntnt p°ol
                                    Crass Section AA1
                    From U.S. EPA. 1992. Storm Water Management
                    for Industrial Activitites: Developing Pollution
                    Prevention Plans and Best Management Practices.

                    supervised by a qualified engineer familiar
                    with state, regional or watershed, and local
                    storm-water requirements.

                    g.      Check Dams
                      Small rock or log dams erected across a
                    ditch, swale, or channel can reduce the speed
                    of water flow in the conveyance. This reduces
                    erosion  and also allows sediment to settle out
                    along the channel. Check dams are especially
                    useful in steep, fast-flowing swales where
                    vegetation cannot be established. For best
                    results,  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 previous (upstream) check dam. Check
                    dams work best in conveyances draining
                    small areas and should be installed only in
                    manmade conveyances. Placement of check
                    dams in streams may require a permit and is
                    not recommended.
  h.    Terraces and
   Terraces and benches are earthen embank-
ments with flat tops or ridge-and-channels.
Terraces and benches hold moisture and mini-
mize sediment loadings in run-off. They may
be used on land with no vegetation or where
it is anticipated that erosion will be a problem.
Terraces and benches reduce erosion damage
by capturing surface run-off and directing it
to a point where the run-off will not cause
erosion or damage. For best results, this point
should be a grassy waterway, vegetated area, or
tiled outlet. Terraces and benches should not
be constructed on sandy or rocky slopes.
  What are some advantages of terraces and

  Terraces and benches reduce run-off
  speed and increase the distance of over-
  land run-off flow. In addition, they hold
  moisture better than do smooth slopes
  and minimize sediment loading of surface

  What are some disadvantages of terraces
  and benches?

  Terraces and benches may significantly
  increase cut and fill costs and cause
  sloughing if excess water infiltrates the
  soil. They are also not practical for sandy,
  steep, or shallow soils.
  /.     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 scour of


                                                                   Protecting Surface Water—Protecting Surface Water
        Figure 7. Outlet Protection
         Pipe Outlet to Flat Area—
         No Well-defined Channel
                        Section AA
           Pipe Outlet to Well-defined
From U.S. EPA. 1992. Storm Water Management
for Industrial Activitites: Developing Pollution
Prevention Plans and Best Management Practices.

channels downstream. It also removes sedi-
ment by acting as a filter medium. Consider
installing outlet protection wherever predict-
ed outflow velocities may cause erosion.
4.   Infiltration  Practices
   These measures encourage quick infiltra-
tion of storm-water run-off by preserving or
providing porous surfaces. Infiltration not
only reduces run-off velocity but also provides
some treatment of run-off, preserves natural
stream flow, and recharges ground water. In
many cases, these added functions are benefi-
cial, but they may make infiltration  practices
inappropriate on unstable slopes, in cases
where run-off may be contaminated, or where
wells, foundations, or septic fields are nearby.

  a.    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
(run-off that flows in a thin, even layer), infil-
trate the land, and drop sediment. Vegetated
filter strips are appropriate where soils are
well drained and the ground-water table is
well below the surface. They will not work
well on slopes of 15 percent or more due to
high run-off velocity. Strips should be at least
20 feet wide and 50 to 75 feet long  in general,
and longer on steeper slopes. If possible, plan
to leave existing natural vegetation in place as
filter strips, rather than planting new vegeta-
tion, which will not function as well until it
becomes established.
  Grassed swales function similarly  to nonveg-
etated swales (see Sediment and Erosion
Control Practices above) 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 (see Sediment and
Erosion Control Practices above) are  sometimes
provided in grassed swales to further slow run-
off velocity, increasing the rate of infiltration. To
optimize swale performance, use a soil which is
permeable but not excessively so; very sandy
soils may not hold vegetation well or may not
form a stable channel structure. Additionally,
grade the swale to a very gentle slope to maxi-
mize infiltration.


Protecting Surface Water—Protecting Surface Water
                      b.    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 eventual-
                    ly infiltrates surrounding soil or is collected by
                    perforated pipes in the bottom of the trench
                    and conveyed to an outflow point. Such
                    trenches can remove fine sediments and solu-
                    ble pollutants. They should not be built in rel-
                    atively 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 contaminated run-off. Run-
                    off can be pretreated using a  grass buffer/filter
                    strip or treated in the trench  with filter fabric.

                           Figure 8. Infiltration Trench
                    From U.S. EPA. 1992. Storm Water Management
                    for Industrial Activities: Developing Pollution
                    Prevention Plans and Best Management Practices.

                    5.   Other Prevention
                       Prevention of surface-water contamination
                    can be accomplished by means other than
                    flow diversion, exposure minimization, sedi-
ment and erosion control, or infiltration.
Many of these practices are simple and inex-
pensive to implement.

  a.    Preventive Monitoring
  This includes automatic monitoring and
control systems, monitoring of operations by
unit personnel,  and testing of equipment.
These processes ensure that equipment func-
tions as designed and is in good repair, so
that spills and leaks, which could contami-
nate surface water, 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 equipment may
provide early warning of problems so that
personnel can intervene before leaks or spills
occur.  Systems that could contaminate sur-
face water if they failed and that could bene-
fit from automatic monitoring or early warn-
ing devices include leachate pumping and
treatment systems, liquid waste distribution
and storage systems at land application units,
and contaminated run-off conveyances.

  b.    Dust Control
  In addition to being an airborne pollutant
itself, dust can be deposited as sediment in
run-off, threatening downstream surface
waters.  Several methods of dust control are
available to prevent this. These include irri-
gation, chemical treatments, minimization of
exposed soil areas, wind breaks, tillage, and
sweeping. For  further information on dust
control, consult the chapter on operating the
waste management system.


                                                                Protecting Surface Water—Protecting Surface Water
  c.    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 wash-
ing removes materials such as dust and waste.
Washing stations can be located near waste
transfer areas or near the site exit.
Pressurized water spray is usually sufficient to
remove dust.  Waste water from vehicle
washing operations should be contained and
handled appropriately.  Discharge of such
waste water requires an NPDES permit other
than the Multi-Sector General Permit.
6.  Mitigation  Practices
  These practices contain, clean up, or recover
spilled, leaked, or loose material before it can
reach surface water and cause contamination.
Other BMPs should be considered and imple-
mented to avoid releases, but procedures for
mitigation should be devised so that unit per-
sonnel can react quickly and effectively to any
releases that do occur. Mitigation practices
include simply sweeping or shoveling loose
waste into appropriate areas of the unit, vacu-
uming or pumping spilled materials into
appropriate treatment or handling systems,
cleaning up liquid waste or leachate using sor-
bents such as sawdust, or applying gelling
agents to prevent spilled liquid from flowing
towards surface water.
   Constructed wetlands can:

   Provide aesthetic as well as water quality
   benefits and areas for wildlife habitat. :
      f method may be subject to multiple
   federal, state and local regulations. In
  ^addition, constructed wetlands may not
   be feasible if land is not available and may
   notv,be effective: until time has been '-,'
   allowed for; substantial plant growth.    :
   Constructed wetlands provide an alterna-
tive to natural wetlands.  In this method, a
specially designed pond or basin, which is
lined in some cases, is stocked with wetland
plants that can manage pollutants through
biological uptake, microbial action, and other
mechanisms, as well as sedimentation. This
process often results in better pollutant
removal than would be expected from sedi-
mentation alone. When designing construct-
ed wetlands, consider that maintenance may
include dredging, similar to that required  for
sedimentation basins; provisions for a dry-
weather flow to maintain the wetlands; mea-
sures to limit mosquito breeding; structures
to prevent escape of floating wetland  plants
(such as water hyacinths) into downstream
areas where they are undesirable; and a pro-
gram of harvesting and replacing plants.
  a.    Discharges to Wetlands
   Other methods of storm-water control are
available, such as discharge to constructed wet-
lands. These methods are less frequently used
and may involve more complicated designs.
The discharge of storm water into natural wet-
lands, or the modification of such wetlands to
improve their treatment capacity, may damage
a wetland ecosystem and, therefore, is subject
to federal, state, and local regulations.
IV.   Methods of
        Calculating  Run-
        on  and  Run-off
  The design and operation of surface-water
protection systems will be driven by storm-
water flow. Calculate run-on and run-off


Protecting Surface Water—Protecting Surface Water
                     flows for the chosen design storm event in
                     order to properly size controls and minimize
                     storm-water impacts. Controls based on too
                     small a design storm event, or sized without
                     calculating flows, may release contaminated
                     storm water. Similarly, systems can also be
                     designed for too large a flow, resulting in
                     unnecessary controls and excessive 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 recur 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—a rainfall event
                     of 24 hours duration and of such a magni-
                     tude that it has a 4 percent statistical likeli-
                     hood of occurring  in any given year.
                        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. This docu-
                     ment, published in 1961, contains rainfall
                     intensity information for the entire United
                     States. Another HDSC document, NOAA Adas
                     2, Precipitation Frequency Atlas of the Western
                     United States comes in 11 volumes, one for the
                     11 westernmost of the contiguous 48 states. It
                     was published in 1973.  Precipitation frequen-
                     cy maps for the eleven western most states are
                     available on the Western Regional Climate
                     Center's web page at
                     < www.wrcc.55age.dri.edu/pcprifreq.html >, and
                     are included in Appendix IY HDSC is current-
                     ly assembling more recent data for some areas.
                     The state or local regulatory agency may be
                     able to provide data for the area.
                        Several methods are  available to help
                     calculate storm-water flows.  The Rational
                                                Method (see sidebar) may be used for calcu-
                                                lating run-off for areas of less than 200 acres.
                                                Another potentially helpful tool for estimat-
                                                ing storm flows is  the Natural Resource
                                                Conservation Service's TR-55 software.4
                                                TR-55 estimates run-off volume from accu-
                                                mulated rainfall and then applies the run-off
                                                volume to a simplified hydrograph for peak
                                                discharge total run-off estimations.
                                                  Rational Method for Calculating Storm-
                                                  Water Run-off Flow
                                                  Q = peak flow rate (run-off), in cubic feet
                                                       per second (cfs)*

                                                  c —  run-off coefficient, unitless. The coef-
                                                       ficient c is not directly calculable,
                                                       so average values based on experience
                                                       are used. Values of c range from 0 (all
                                                       infiltration, no run-off) to 1 (all run-
                                                       off, no infiltration). For example, flat
                                                       lawns with sandy soil have c of 0.05
                                                       to 0.10, while concrete streets have c
                                                       of 0.80 to 095.
                                                  i =  average rainfall intensity, in inches per
                                                       hour, for the time of concentration, tc,
                                                       which is a calculable flowtime from
                                                       the most distant point in the drainage
                                                       area to the point at which Q is being
                                                       calculated. Once tc is calculated and a
                                                       design storm event frequency selected,
                                                       i can be read from a graph such as
                                                       that shown in Figure 9.
                                                  a =  drainage area, in acres. The drainage
                                                       area is the expanse in which all run-
                                                       off 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-in/hr. Since! ac-in/hr =
                                                  1.008 cfs, however, the units are interchangeable
                                                  with a negligible loss of accuracy, and units of cfs
                                                  are usually desired for subsequent calculations.
''''TR-55, Urban Hydrology for Small Watersheds Technical Release 55, presents simplified procedures to calcu-
late storm run-off volume, peak rate of discharge, hydrographs, and storage volumes required for floodwater
reservoirs. These procedures are applicable in small and especially urbanizing watersheds.  TR-55 can be
downloaded from NRCS at <www.ncg.nrcs.usda.gov/tech_took.html>.


                                                                      Protecting Surface Water—Protecting Surface Water
   Computer models are available to aid in the
design of run-on and run-off control (see side-
bar). EPA's Storm Water Management Model
(SWMM) is a comprehensive 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 may be possible to perform
both single-event and continuous simulation
on catchments having storm sewers and natur-
al 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 necessary to
ensure that their methodology is applicable to
design for industrial units.  As with all com-
puter models, these should be used as part of
the array of design tools, rather than as a sub-
stitute for careful consideration  of the unit's
design by qualified professionals.
   Figure 9. Typical Intensity-Duration-
             Frequency Curves
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.
BASINS: A Powerful Tool for Managing
Watersheds. A multi-purpose environmental '
analysis system that integrates a geographical
information system,(GIS), national watershed
data, and state-of-the-art environmental assess-
ment and modeling took into one convenient

Storm Water'Management Model (SWMM).
Simulates the movement of precipitation and pol-
lutants from the ground surface dirough pipe and
channel networks, storage treatment units, and
receiving waters.

The Source Loading and Management Model
(SLAMM). Explores relationships between sources
of urban run-off pollutants and run-off quality. It
now 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'mdsdy used as a planning tool,
to better understand sources of urban run-off pol-
lutants and dieir 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 die effect
of management decisions on water, sediment, and
pesticide yield with seasonable accuracy for
ungauged rural basins throughout the United

Pollutant Routing Model (P-ROUTE). Estimates
aqueous poEiitant concentrations on a reach by
reach flow basis; using 7Q10 or mean flow.:,
EnhanoSd Stiem Water Quality Model (QUAL2E).
Simulates the major reactions of nutrient cycles,
algalproduction^benthic and carbonaceous
demand, atmospheric reaeration 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 with field sampling for identi-
fying the magnitude and quality charactersitics of
nonpoint sources  ,


I Pro
Protecting Surface Water—Protecting Surface Water
                           Action Items for  Protecting Surface  Water
                   Conduct the following activities when designing or operating a units surface-water protection
                   systems.                                                             i

                   Q     Comply with applicable National Pollutant Discharge Elimination System (NPDES)
                          and state permitting requirements.

                   O     Assess operating practices, potential pollutant sources, and surface-water flows to
                          determine the need for and type of storm-water controls.

                   D     Implement baseline and activity-specific best management practices (BMPs), such as
                          good housekeeping practices and spill prevention and response plans.

                   Q     Choose a design storm event, such as the 24-hour, 25-year event, and obtain precip-
                          itation intensity data for that event to size storm-water control devices.

                   Q     Select and implement site-specific BMPs, such as diversion dikes, sedimentation
                          basins, and outlet protection.

                   Q     Devise a system for inspecting and maintaining the chosen controls, possibly as part
                          of the operating plan.


                                                                 Protecting Surface Water—Protecting Surface Water
Florida Department of Environmental Regulation. No date. Storm water management: A guide for

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.  1995.  Process design manual: Land application of sewage sludge and domestic septage.

U.S. EPA.  1995.  Process design manual: Surface disposal of sewage sludge and domestic septage.

U.S. EPA.  1995.  NPDES Storm Water Multi-Sector General Permit information package.

U.S. EPA.  1995.  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.  1994. Project summary: Potential groundwater contamination from intentional and non-intentional
storm water infiltration. EPA600-SR-94-061.

U.S. EPA.  1994.  Storm water pollution abatement technologies. EPA 600-R-94-129.

U.S. EPA.  1993.  Overview of the storm water program. EPA833-F-93-001.

U.S. EPA.  1993.  NPDES storm water program: Question and answer document, volume 2.

U.S. EPA.  1992.  An approach to improving decision making in wetland restoration and creation.

U.S. EPA.  1992.  NPDES storm water program: Question and answer document, volume 1.

U.S. EPA.  1992.  NPDES storm water sampling guidance document. EPA833-B-92-001.


Protecting Surface Water—Protecting Surface Water
                                             Resources (cent.)
             U.S. EPA. 1992. Storm water general permits briefing. EPA833-E-93-001.     ;

             U.S. EPA. 1992. Storm water management for industrial activities: Developing pollution prevention plans
             and best management practices.  EPA832-R-92-006.

             U.S. EPA. 1992. Storm water management for industrial activities: Developing pollution prevention plans
             and best management practices.  Summary guidance.  EPA833-R-92-002.

             Viessman Jr., 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 qual-
             ity report. WQ-R-93-015. September.                                     ;


        Part IV
Protecting Ground Water

  Chapter 7: Section A
 Assessing Risk Section


I.  An Overview of the Approach in the Guide    ;   7A-3
   A. Assessing Risk    7A-3
      1. The Approach to Liner Performance and Liner Assumptions in the Guide   7A-4
      2. What We Know About Liners and Caps 7A-5
   B. Request for Comments  \   7A-6

II. Identification of Contaminants  7A-7
   A. Exposure Assessment: Understanding Fate and Transport 7A-9
   B. Risk Characterization: The 3-Tiered Approach  7A-12
      1. Tier 1: National Evaluation    7A-15
      2. Tier 2: Lacation Adjusted  Evaluation  .:  7A-18
      3. Tier 3: Site-Specific Ground-Water Fate and Transport Analysis     :   7A-24

Action Items for Assessing Risks to  Ground Water   7A-30

Resources   -   7A-31

  Table 1:  Earth's Water Resources :   7A-1
  Table 2:  List of Constituents with Maximum Contaminant Levels (MCLs) 7A-8
  Table 3:  Example National Evaluation Lookup Table for Landfills  7A-16
  Table 4:  Example National Evaluation Lookup Table Comparison Results ;   7A-17
  Table 5: Example Site-Specific Parameters ,   7A-21
  Table 6: Example Site-Specific, Ground-Water Fate and Transport Models    !.  7A-28

Figures:                                                                    |
  Figure 1: Representation of Fate and Transport Analysis   7A-10
  Figure 2: Process Diagram: Use of National Evaluation Lookup Tables   7A-19
  Figure 3: Example Input Screens  for Tier 2 Model 7A-22


                                                                Protecting Ground Water—-Assessing Risk Section
                             Assessing  Risk
        Protect ground water by assessing risk associated with the
        waste management practices and tailoring management con-
        trols accordingly.  Use the three-tiered evaluation approach to
        determine recommended liner systems and whether land appli-
        cation is appropriate. Follow guidance on liner design and land
        application practices.
            round water
            is the water
            found in
            the soil
            and rock
that make up the Earth's
surface. Although it
comprises only about
0.69 percent of the
Earth's 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,  far surpassing lakes and rivers (see
Table I).1 Statistics about use of ground water
as a drinking water source underscore the
importance of the resource. Ground water is a
source of drinking water for more than half of
the people in the United States.2 In rural
areas, 97  percent of households rely on
ground water as  their primary source of
drinking water.
    In addition to its importance for domestic
water supplies, ground water is heavily used
                           Table 1.
                    Earth's Water Resources
Resource • Percent of Percent of
Total Nonoceanic
Ice caps and glaciers
Ground water and soil moisture
Lakes and Rivers
Adapted from Berner, E.K. and R. Berner. 1987. The Global Water
Cycle: Geochemistry and Environment
                    by industry and agriculture. It provides
                    approximately 37 percent of irrigation water
                    and about 18 percent of the water used by
                    industry.3 Ground water has other important
                    environmental functions as well, such as pro-
                    viding recharge to lakes, rivers, wetlands, and
                      Water beneath the ground surface occurs in
                    an upper unsaturated or 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
1 Berner, E. K. and R. Berner. 1987. The Global Water Cycle: Geochemistry and Environment.
2Surface 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.
3 Excludes cooling water for steam-electric power plants. U.S. Geological Survey. 1998. Estimated Use of
Water in the United States in 1995. <www.usgs.govAvatuse>.


Protecting Ground Water—Assessing Risk Section
                    water may be present.4 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 ground water in the sat-
                    urated zone, from which
                    most ground-water with-
                    drawals are  made.
                      Because ground water is
                    a major source of water for
                    drinking, irrigation, and
                    process water, the public,
                    industry, and federal, state,
                    and local governments are
                    all concerned about
                    ground-water contamina-
                    tion. There  are many
                    threats to the quality of
                    ground water, such as infil-
                    tration of fertilizers and
                    pesticides, contamination
                    from faulty  or overloaded
                    septic fields, and releases
                    from industrial facilities,
                    including waste manage-
                    ment units.
                      Because ground water
                    flows beneath the surface of
                    the earth, and moves very
                    slowly in many aquifers,
                    years may elapse before
                    contamination is discov-
                    ered and its sources identi-
                    fied. Once ground water
                    has been contaminated,
                    remedial action and moni-
                    toring can be costly, can require years of effort
                    or in some circumstances, might be technical-
                    ly infeasible. For these reasons, it is extremely
                    important to prevent ground-water contami-
                    nation if possible or minimize impacts by
                    implementing controls tailored to the risks
          Ground Water in the Hydrologic Cyde

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-
tions (recharge) to ground water come 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
than the water table. Most water entering the ground as pre-
cipitation returns  to the atmosphere, by evapotranspiration.
Most water that^reaches the saturated zone eventually
returns to the surface by flowing to points of discharge,
such as rivers, lakes, or springs. Soil, geology, and climate
will determine the amounts and rates of flow among the
atmospheric, surface, and ground-water systems.
                associated with the waste. Natural subsurface
                processes, such as biodegradation, sorption,
                and precipitation, can attenuate compounds in
                the ground water before they reach receptors.
                    1 U.S. EPA. 1989. Glossary of Environmental Terms and Acronym List.


                                                                  Protecting Ground Water—Assessing Risk Section
I.     An Overview  of

       the Approach  in

       the Guide
  The guidance recommends tailoring pro-
tective liner systems to the wastes that are
managed in a unit and evaluating whether
land application of a waste is appropriate
using a three-tiered approach to ground-
water modeling and risk assessment. The
type of assessment you choose depends, in
part, on the complexity of a site and the char-
acteristics of the waste. All three tiers rely on
ground-water modeling to evaluate the
potential for ground-water contamination.
Each successive tier incorporates more site-
specific data to tailor recommendations to
your circumstances.
  The modeling tool for Tiers 1 and 2 is the
EPA Industrial Waste Evaluation Model
(IWEM) incorporated into the CD ROM ver-
sion of this guidance. This is a stand-alone,
simple-to-use model that does not require
previous modeling experience. Tier 1
National Evaluation lookup tables can be
found in Appendix I.
  Tier 1 - National Evaluation: Once you
  know the concentrations of constituents in
  a waste, generic tables provide design rec-
  ommendations (liner system or waste
  application concentrations). If the waste
  contains several constituents, choose the
  most protective design indicated for any of
  the constituents. This tier of analysis is the
  most conservative and will generally rec-
  ommend more stringent controls. It is
  designed to be more conservative because
  it captures a wide range of site conditions
  across the country.

  Tier 2 - Location-Adjusted Evaluation: You
  can enter data for up to seven of the most
   sensitive waste and site-specific variables
   to assess whether an alternative design will
   be protective. This tier is generally less
   conservative because it incorporates an
   intermediate level of specificity in the data.

   Tier 3 - Comprehensive Risk Assessment
   This tier relies on a comprehensive analysis
   of site characteristics to determine a design
   that will be protective. Tier 3 uses substan-
   tial amounts of site-specific data.
A.    Assessing Risk
   IWEM analyzes three liner scenarios over a
10,000 year time frame. The Tier 1 and 2 risk
evaluations work as follows. IWEM incorpo-
rates 191 constituents with toxicity reference
levels that are either drinking water maxi-
mum contaminant levels (MCLs) set under
the Safe Drinking Water Act or health-based
numbers (HBNs) derived from several
sources. First, we have identified a bench-
mark concentration (MCL or HBN) for each
constituent in a monitoring well associated
with a waste management unit. The goal is
not to exceed the benchmark concentrations
in the monitoring well. The model starts from
this benchmark concentration in the monitor-
ing well and back calculates the effects of
dilution and attenuation and release rate from
a unit to determine the leachate constituent
concentrations for wastes that can be protec-
tively managed in a particular unit design.
For land application, the model recommends
whether wastes can be protectively land
applied, based on leachate constituent con-
centrations. Finally, the model caps leachate
concentrations from an industrial solid waste
management unit at a level no higher than
1000 mg/1 for any single constituent, because
higher leachate concentrations are not expect-
ed from these waste management units. The
39 hazardous waste toxicity characteristic
constituents (TC) are capped at their TC lev-


Protecting Ground Water—Assessing Risk Section
                    els because concentrations above those levels
                    are hazardous waste.
                      The technical background document
                    accompanying the model thoroughly explains
                    the model, including the parameters that
                    have the greatest effect on modeling results.
                    The-sensitive parameters that a user can
                    input at Tier 2, in addition to waste charac-
                    teristics, are:
                    •   Leakage rate,
                    •   Surface area of the waste management
                    •   Depth to water table,
                    •   Distance to the well,
                    •   Thickness of the aquifer,
                    •   KOC (retardation rate for organic con-
                        stituents), and adjusted Kd for metals,
                    •   A, (coefficient defining hydrolysis or
                        biodegradation rate).
                        One of the most sensitive parameters is
                    the leakage rate or the rate at which leachate
                    is released from a unit and moves into sub-
                    surface soils.-The leakage rate is influenced
                    by a number of factors. Some key factors are
                    the amount of precipitation, the level of liq-
                    uid in the unit (head), and the hydraulic
                    conductivity of the liner material. Hydraulic
                    conductivity refers to the capacity to transmit
                    fluid. Low hydraulic conductivity slows
                    leachate migration out of a unit. For synthet-
                    ic liners, the occurrence of tears, rips or holes
                    also influences leakage rate.
                       Units that rely only on natural soils under-
                    lying the unit, including units for direct land
                    application of waste, generally have higher
                    leakage rates. A single clay or synthetic liner
                    can reduce the leakage rate to some extent.
                    However, composite and double liners that
                    combine two or more layers of liner material
                    with leachate collection  and leak detection
                    (for double liners) significantly increase the
effectiveness of the containment system in
minimizing leakage to the subsurface during
the period when the leachate collection sys-
tem is actively managed.
   For a landfill that no longer receives waste
and for surface impoundments and waste
piles where waste remains in place at closure,
the cap that is placed over the unit becomes
an important component of the final contain-
ment system. One key purpose of the final
cap is to minimize infiltration of precipitation
which generates leachate that may eventually
leak into subsurface soils and migrate to
ground water. The liner system in the short
term, and the cap and the liner system
together in the long term, to a large extent
determine the leakage rate from the unit. The
leakage  rate that is associated with various
unit designs is one of the most sensitive vari-
ables in ground-water risk modeling to evalu-
ate which liner system is protective for man-
aging particular wastes in a unit.

     1.  The Approach to Liner
        Performance and Liner
        Assumptions in the Guide
   The guide recommends a comprehensive
approach to design, construction, operation
and long term care of a waste management
unit to minimize the potential for many of
these problems. This includes:
    Recommending liner design based on
    characteristics of waste managed in the
    Strong emphasis on construction quality
    assurance and control.
    Emphasis on compatibility between the
    liner and the waste .

    Continuing operation and maintenance
    practices to protect liner performance.


                                                                      Protecting Ground Water—Assessing Risk Section
 •   Ground-water monitoring as an integral
     component of a protective management
     system, to assess liner performance.
 •   Corrective action to clean up releases.
 •   Closure with a cap that meets or exceeds
     the design of the liner (infiltration
     through the cap equal to or less than
     leakage through the liner).
 •   Post closure care and monitoring to
     maintain the cap for the time period nec-
     essary to ensure the waste no longer
     poses a risk to human health.
   In addition, assumptions concerning liner
 performance have a significant impact on the
 modeling results. A brief summary of the
 basis for leakage rate in the modeling sce-
 nario for each liner type follows (these per-
 formance levels remain constant for the
 10,000 year time frame of the model):

   No liner: In Tier 1, monte carlo analysis of
   a range of leakage  rates, based on water
   balance and native soil type for nearest
   meteorological station. In Tier 2, the
   model can provide a regional infiltration
   rate, based on user-specified location.

   Single liner: consisting of three feet of
   compacted clay with a hydraulic conduc-
   tivity of 10'7 cm/s.  In Tier 1, monte carlo
   analysis of a range of infiltration rates,
   based on water balance  for nearest meteo-
   rological station. In Tier 2, the model can
   provide users with a regional infiltration
   rate, based on user-specified location.

   Composite liner the engineered system
   includes leachate collection. Landfills are
   assumed to have a constant hydraulic head
   of no more than 12 inches. The leakage
   rate, in Tier  1, is a single value calculated
   using an equation developed by Bonaparte
   et al5, assuming one .005 in.2 hole per  acre.
   For landfills, the leakage rate is 0.1 g/a/d
   and for surface impoundments, 0.9 g/a/d
   This represents a well designed and
   installed liner.
     2. What We Know About Liners
        and  Caps
   In general, we have learned much over the
 past 20 years  about the performance of liner
 systems and caps, and there have been many
 improvements in construction, installation,
 and quality assurance and control proce-
 dures. However, we recognize that there is
 still uncertainty associated with liner perfor-
 mance, in the near term as well as in the long
 term. While some studies indicate that engi-
 neering properties of liners may last for hun-
 dreds of years, there are a variety of factors
 that may influence longevity and perfor-
 mance, such as poor construction, installation
 or facility operation, or geologic movement
 below the liner that can cause holes, tears or
 larger failures. Some defects are likely to have
 little to moderate effect on the leakage rate.
 Other defects may have a significant effect
 and even necessitate corrective action.
  We have conducted some preliminary sen-
 sitivity analyses to compare  leakage rates
 from a variety of theoretical composite liner
 scenarios. Scenarios varied the size of holes
 and tears and the number per acre; contact
 between the synthetic and the clay layer; the
 conductivity of the underlying clay layer; and
 the head of liquid on top of the synthetic
 liner. Results of these preliminary analyses
 provided a range  of leakage  rates ranging
 from 1.5E-08 m/year to an unrealistically
 high 353 m/year.  As a comparison, the leak-
 age rate used in our composite liner scenario
is 3.3E-05 m/yr (landfills). These results indi-
 cate several key areas to pursue further analy-
ses. 1) What empirical data are available con-
cerning liner defects at the time of installa-
tion; and what data are available concerning
actual leakage  rates at operating industrial
' Bonaparte, R., Giraud, J.R, and Gross, B.A. 1989. "Rates of Leakage Through Landfill Liners,"
Proceedings of Geosynthetic '89 Conference, Volume 1.


Protecting Ground Water—Assessing Risk Section
                    waste units to serve as a basis for identifying
                    reasonable performance scenarios? 2) We cal-
                    culate the leakage rate for our modeling sce-
                    nario using the equation cited above (and dis-
                    cussed in the IWEM Technical Background
                    Document). We  are looking for information on
                    the validity of the equation over a wide range
                    of conditions. 3) If we were to model a range
                    of infiltration rates for composite liners, what
                    is a reasonable  range to include in the analy-
                    sis? (A more thorough discussion of the sensi-
                    tivity analyses is in the IWEM Technical
                    Background Document, contained on the CD
                    ROM and available in the docket.)
                       Another area of uncertainty is the fate of
                    constituents within a unit. Over time, a number
                    of degradation  processes may be under way
                    that reduce the hazards associated with some
                    constituents. On the other hand, a landfill with
                    an intact cover may be reasonably dry and thus
                    degradation may be quite slow (also reducing
                    leachate generation). Other toxic constituents,
                    such as heavy metals, will not degrade.
                       Covers present continuing engineering
                    challenges over time, because they are more
                    susceptible to factors such as freezing and
                    thawing, wetting and drying, temperature
                    fluctuations, root infiltration, and subsidence.
                    Covers are, however, not subject to chemical
                    attack from waste constituents, nor are they
                    subject to the same stresses from waste place-
                    ment as a bottom liner. Also, final covers are
                    simpler to repair, which would help control
                    the risk of infiltration into the landfill, assum-
                    ing there is an  active program to monitor or
                    periodically replace the cover. Unless the final
                    cover is regularly repaired or replaced, the
                    bottom liner  could outlast the cover. While
                    covers containing a synthetic membrane are
                    likely to prevent precipitation from entering a
                    closed unit while they are performing as
                    designed and there are no failures, uncorrect-
                    ed failure of a cover would allow precipitation
                    to enter the unit. After leachate removal is
                    discontinued, this could lead to a "bathtub
effect" where the unit has increasing leachate
volumes and hydraulic head that could lead
to increased leakage rates or overflow.
B.     Request For Comments
   We invite comments on all aspects of the
model, the values, and data sources used for
specific parameters, and the modeling scenar-
ios for liner performance, including the fol-
•   Is the cap of 1000 mg/1 concentration for
    most constituents in leachate from an
    industrial solid waste, management unit,
    realistic?  If not, provide data on which
    waste units generate leachate at higher
    concentration levels and what those levels
    are likely to be.
•   What approaches are reasonable to
    address the question of the changing
    effectiveness of liners and caps over time?
•   Provide data on the occurrence of defects
    in liners at the time of installation and on
    changes in leakage rate or other data or
    indicators of possible changes in liner
    defects over time.
•   The hazardous waste program deals with
    liner/cap  uncertainties by requiring treat-
    ment prior to disposal. How should such
    uncertainties be dealt with for non-haz-
    ardous industrial wastes? One possibility
    is to rely  on quality assurance and control,
    long-term monitoring and corrective action
    to address non-hazardous waste. Where
    uncertainties are too great, we could rely on
    the hazardous waste program to list such
    wastes as hazardous  and require treatment.
    A second approach could be to  rely on
    treatment of certain non-hazardous wastes.
    What other approaches are available?
•   Should the composite liner scenario, in
    Tier 1, use a different leakage rate, or
    monte carlo analysis to reflect a range of


                                                                  Protecting Ground Water—Assessing Risk Section
    performance levels, rather than a single
    value? What values should be used, and
    what is the basis for them?
   We are also obtaining peer review of the
ground-water model by a group of technical
experts who have been commissioned to pro-
vide an independent analysis of the model
and the way it is used in the guidance. The
results of the peer review will be published in
the Federal Register, so that interested parties
may obtain copies of the review and take it
into account as they prepare their own com-
ments on the ground-water protection com-
ponents of the guide.
   Construction and installation quality assur-
ance and quality control are critical to ensur-
ing liner performance. The guidance is
intended to reflect the most up-to-date instal-
lation practices and techniques and the most
appropriate materials and techniques for
installing a final cap on a unit.
•   Are there additional practices and tech-
    niques that should be reflected in the
•   For those with experience installing liners
    and caps and operating lined units, how
    do you measure liner performance and
    what are your experiences over time
    monitoring liner and cap performance?
II.    Identification  of
   The guidance addresses constituents with
toxicity reference levels (TRLs) (i.e., MCLs
and HBNs). These constituents have been
included because they have human health
concentration levels for exposure through
drinking water. MCLs are drinking water
standards, set in the Safe Drinking Water Act,
which establish the maximum permissible
level of a contaminant allowed in drinking
water. A list of constituents with MCLs used
in this guidance's ground-water risk modeling
can be found in Table 2. A HBN is a level
which is derived from reference doses or ref-
erence concentrations which estimate daily
exposure to a constituent that is likely to be
without appreciable risk of deleterious effects
during a human lifetime. For further informa-
tion on TRLs, see the User's Guide and
Background Document for the Industrial Waste
Management Evaluation Model.
   This guidance addresses both MCLs and
HBNs, to the extent available, for each con-
stituent. The constituents specifically
addressed by this guidance include both
organic and inorganic chemicals. Organic
chemicals are chemical compounds contain-
ing carbon.6 Inorganic chemicals include
chemical substances of mineral origin, such
as cadmium and chromium. For the 191 con-
stituents included in the guidance, 51 have
an MCL,  189 have an HBN value, and 41
have both. TRLs may vary from state to  state.
States can impose more stringent drinking
water standards than  federal MCLs.7 To keep
the software developed for this guidance up
to date and to accommodate concerns at lev-
els different from the  current TRLs, the TRL
values can be modified by the user of the
   A first step in determining the most appro-
priate waste management unit design is  to
identify the constituents in the waste and
expected leachate concentrations from the
waste. For information on determining
leachate concentrations, see the characteriz-
ing waste chapter.
 Some regulatory definitions include carbon monoxide, carbon dioxide, etc. as organic compounds, some
definitions exclude them as organic compounds. Lee, C. 1992. Environmental Engineering Dictionary, 2d.

7For example, a state can make secondary MCLs, which are not federally enforceable standards, mandato-
ry, or a state may use different exposure assumptions which result in a different HBN.


Protecting Ground Water—Assessing Risk Section
                                                               Table 2.
                                   List Of Constituents with maximum Contaminant Levels (MCLs)
                   Organics with an MCL                   rng/1
                   Benzene                                0.005
                   Benzo[a]pyrene                          0.0002
                   Bis(2-ethylhexyl)phthalate                0.006
                   Brornodichloromethane*                 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-           0.0002
                   Dichlorobenzene 1,2-                    0.6
                   Dichlorobenzene 1,4-                    0.075
                   Dichloroethane 1,2-                     0.005

                   Dichloroethylene cis-1,2-                 0.07
                   Dichloroethylene trans-1,2-               0.1
                   Dichloroethylene l,l-(Vinylidene chloride) 0.007
                   Dichloropropane 1,2-                    0.005
                   Endrin                                 0.002

                   Ethylbenzene                           0.7
                   Ethylene dibromide (1,2-Dibromoethane)  0.00005
HCH (Lindane) gamnia-

Heptachlor epoxide
Methylene chloride
Polychlorinated biphenyls
TCD Dioxin 2,3,7,8-
Tetrachloroethylene  >
(chlorinated camphenes)
Tribromomethane (Bromoform)*
Trichlorobenzene 1,2,4-
Trichloroethane 1,1,1-
Trichloroethane 1,1,2-
Vinyl chloride
Xylenes            \




                   Inorganics with an MCL
                  * Listed as Total Trihalomethanes (TTHMs), constituents do not have individually listed MCLs.
                  ** Silver is a secondary MCL. Secondary MCLs (SMCLs) are non-enforceable guidelines regulating contami-
                  nants that may cause cosmetic effects, such as skin or tooth discoloration, or aesthetic effects, such as taste,
                  odor, or color, in drinking water.


                                                                   Protecting Ground Water—Assessing Risk Section
A.     Exposure Assessment:
        Understanding Fate
        and Transport
   A source of ground-water contamination
from a waste management unit is the release
of leachate. Residents who live close to a
waste management unit 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) released during use of
ground water such as during showering,
when volatile compounds can be released to
the air.
   Releases from a waste management unit
and subsequent transport of constituents to
ground water are affected by three types of
factors: waste characteristics, site  characteris-
tics, and liner system design (as the primary
containment system to minimize release of
constituents of concern out  of a unit).
   First, the physical, chemical, and biological
properties of the waste/constituents affect the
potential for constituents to leach or other-
wise be released into the environment. For
example, waste characteristics influence how
a liner system prevents or mitigates the
migration of leachate. Wastes that are highly
acidic or alkaline can dissolve soil minerals
and thus increase the hydraulic conductivity
or permeability of a  compacted clay liner.
Waste constituent characteristics affect the
movement or transport of constituents
through soil and ground water. For example,
wastes with a density lower  than ground
water tend to concentrate in the upper por-
tions of an aquifer, while those with a higher
density concentrate in the lower portions.
The viscosity (tendency to resist internal
flow) of specific contaminants affects their
rate of migration through soil and within an
aquifer. Solubility (which affects the mobile
concentration), chemical structure, and many
other waste constituent properties can affect
contaminant migration.
   Second, site characteristics, including geo-
logic setting and hydrology, may inhibit or
facilitate movement of constituents. Natural
subsurface processes, such as biodegradation,
sorption, and precipitation, can attenuate
compounds in the ground water before they
reach receptors. Alternatively, fractures in
rocks can act as conduits and water can move
through them quickly carrying contaminants.
   Finally, engineered liners have a variety of
properties that contain constituents to vary-
ing degrees. Compacted clays, geomem-
branes, and composite liners act as hydraulic
barriers to minimize release of leachate.8
Compacted clay liners also can reduce the
concentration of constituent levels through
attenuation. In addition to liners, final covers
placed on waste management units after the
final receipt of waste minimize  infiltration  of
water into a waste management unit and
thereby further reduce leachate generation
and potential release.9
How do contaminants move
from waste management units
to ground  water?
   Figure 1 illustrates the concept of aqueous
phase waste constituent movement from a
waste management unit to a monitoring well.
As can be seen in the figure, contaminant
concentrations are typically highest near the
   Waste constituents from a waste manage-
ment unit migrate through the unsaturated
and saturated zones where physical, chemi-
cal, and biological processes act upon them.
The type of geological material below the unit
also affects  the rate of movement because of
differences  in hydraulic conductivity. More
"For further information on liners, see the section on designing and installing liners.

Tor further information on covers and impact on infiltration, see the chapter on performing closure and
post-closure care.


Protecting Ground Water—-Assessing Risk Section
                                   Figure 1. Representation of Fate and Transport Analysis
                                                                                       Monitoring Well
                                                                              roiniorMonnQnnii    7^ /   y
                                                                             /BWUMMW ConCMlbWUQft vJmiSa /  /
                                                                                OMSiaglL     //  /
                                                                              I  I  I  I  I   I  I  I
                     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 (see
                     textbox on examples of soil permeability).
                     The physical and chemical composition of
                     the geologic material is equally important.
                     Fine-textured material with a high clay con-
                     tent tends to impede contaminant migration
                     both by having a low hydraulic conductivity
                     and through the effects of ion exchange and
                     physical adsorption.10

                     Contaminant movement through unsaturated zone
                        As waste constituents migrate, geological
                     materials and biological processes interact
                     with waste constituents. These interactions,
                     which are called attenuation, lead to immobi-
                     lization of potential ground-water contami-
                     nants. Attenuation processes are dependent
                     upon pH, temperature, vapor pressure, and
                     other compounds in the subsurface environ-
                     ment.  Attenuation processes include sorption
                     of cations and anions on soil mineral sur-
                                              faces, such as clays, and direct precipitation
                                              of molecules from solution.11  Sorption is the
                                              process by which leachate molecules adhere
                                              to the surface of individual clay, soil, or sedi-
                                              ment particles. Sorption causes a decrease in
                                              the total dissolved solids in the leachate.
                                              Clays are good sorbants for two reasons: sur-
                                              face charge and high surface area.
                                                         Examples of Permeability of
                                                      Common Natural Soil Formations
Coefficient of Permeability
                                                 Mississippi river deposits
                                                 Dune sand
              0.02 to 0.12
              0.1 to 0.3
              < 0.0000001
                                                 Sharma, H., and S. Le;wis. 1994. Waste
                                                 Containment Systems, Waste Stabilization, and
                                                 Landfills.          •  -,'""'""'
"Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment, Prevention, and

"These attenuation processes can occur in both the vadose and saturated zones.


                                                               Protecting Ground Water—Assessing Risk Section
                        Samples of Attenuation Processes

    Attenuation processes are dependent upon pH, temperature, pressure, and other
compounds in the subsurface environment.
   Biological degradation: decomposition of a substance into more elementary com-
pounds by action of microorganisms such as bacteria. Sullivan. 1993. Environmental
Regulatory Glossary, 6th Ed. Government Institutes.
   Bio-uptake: the uptake and, at least temporary, storage pf a chemically an exposed
animal. The chemical can be retained in its original form and/or modified by enzy-
matic and non-enzymatic reactions in the body. Typically, the concentrations of-the
substance in trie organism exceed the concentrations in the environment since the
organism will store the substance and not excrete it. Sullivan. 1993. Environmental
Regulatory Glossary, 6th Ed. Government Institutes'.-      '      -                ^,
   Filtration: physical process whereby solid particles and large dissolved molecules
suspended in a fluid  are entrapped or removed by the pore spaces of the soil and
aquifer media. Boulding, 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 trans-
formation process changes the  chemical structure of the.substance. Sullivan. 1993.
Environmental Regulatory Glossary, 6th Ed. Government-Institutes.
   Oxidation/Reduction (Redox) reactions: involve a transfer of electrons and, there-
fore, a change'in the  oxidation state of elements. The chemicaLproperties 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 the mobility of
constituents, such as metals. Unlike sorption, precipitation is not generally reversible.
Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment,
Prevention, and Remediation.
   Sorption: the ability of a chemical to partition between the liquid and solid  phase
by determining its affinity for adhering to other solids in the system such as soils or
sediments; The amount of chemical that "sorbs" to solids-ahd does not move through
the environment is dependent upon the characteristics oCIhe chemical, the character-
istics of the surrounding soils and sediments, and the quantity of the chemical.
Sorption generally irreversible. Sorption often includes both adsorption and ion
exchange.     '. _'                              .   :.;.:;: -."••-  •--:""\       -    -.-.


Protecting Ground Water—-Assessing Risk Section
                       In addition, microorganisms frequently are
                    the catalysts or promoters of reactions in the
                    subsurface.  Microorganisms can break down
                    wastes, produce various organic acids, and
                    use up available oxygen supplies creating
                    anaerobic environments. Whether soil con-
                    ditions are oxidizing (aerobic) or reducing
                    (anaerobic) will strongly affect the types of
                    microbial activity and contaminant degrada-
                    tion processes that may occur. For more
                    information on specific attenuation processes,
                    see the text box on the previous page.
                    Contaminant movement through the
                    saturated zone
                       Eventually, the waste constituents can
                    reach the saturated zone where dilution or
                    dispersion can occur. Dilution reduces the
                    concentration of constituents but does not
                         Examples of Attenuation Mechanisms
                              for Specific Contaminants
                                        Attenuation mechanisms



Volatile organic
compounds (VOCs)
Bagchi, A. 1994. Design, Construction, and
Monitoring of Landfills.
                                        Adsorption, precipitation

                                        Adsorption, precipitation


                                        Adsorption, precipitation

                                        Adsorption, precipitation

                                        Adsorption, precipitation,
                                        redox reactions

                                        Precipitation, sorption

                                        Adsorption, anion
                                        Adsorption, precipitation
                                        Biological uptake
alter their chemical structure. Dilution is
directly related to ground-water velocity and
the size of the leachate plume tends to
increase with more rapid ground-water flow.
   Attenuation also occurs in the saturated
zone. Attenuation processes can remove or
degrade waste constituents through filtration,
sorption, precipitation, and hydrolysis. For
example, filtration is the entrapment of solid
particles and large dissolved molecules in the
pore spaces of the soil and aquifer.
   If contamination reaches a monitoring
well, corrective action may need to be initiat-
ed to protect human health and the environ-
ment.  The overall goal of any corrective
action should be to perform a technically and
economically feasible risk-reduction,
designed to achieve a cleanup standard at a
specified point on the facility property.
Using the ground-water pathway as an exam-
ple, corrective action for new units should
have as a goal a reduction of constituent con-
centration levels to the ground-water protec-
tion standards, that is the TRL (e.g., a MCL
or HBN) at the monitoring point. For more
information on corrective action, see the
chapter on taking corrective action.

B.     Risk Characterization:
        The 3-Tiered Approach
   The three assessment tiers and the IWEM,
the ground-water model included in this
guidance  for Tiers 1  and  2, can be used to
help select protective practices to manage
waste constituents. First determine state
requirements for liners and waste limits for
land application and comply with those
requirements. IWEM and the three-tiered
assessment recommended here can help
choose management controls where there is
flexibility for site-specific determinations in
state regulations.


                                                                     Protecting Ground Water—Assessing Risk Section
   It is important to understand how Tier 1
and 2 incorporate risk assessment. The goal
in choosing a liner design or waste applica-
tion rate is to prevent, to the extent possible,
or to minimize ground-water contamination.
Defining a monitoring well (rather than a
drinking water well) as the point to measure
benchmark concentrations is a way to asses
performance of the liner system and potential
migration of contaminants from the unit. The
human health benchmark values serve as a
flag for additional action to characterize a
release, correct problems with the liner, and
cleanup contamination.
   At Tier 1, the model analyzes a monitoring
well set at 150 meters from the unit boundary
to accommodate states that have adopted a
non-degradation policy to protect ground
water for current and future users. At Tier 2,
IWEM allows a user to set an alternative dis-
tance to the monitoring well. This approach
recognizes that, on a site-specific basis, an
alternative distance to monitoring wells may
be appropriate, as long as the distance is
agreed to in consultation with all the interested
parties. EPA's Composite Model for Leachate
Migration with Transformation Products is the
basis for the Tier 1 and 2 analyses.
  EPA's Composite Model for Leachate Migration
with Transformation Products
   The Tier 1 and Tier 2 modeling tools are
based on EPA's Composite Model for
Leachate Migration with Transformation
Products (EPACMTP).12 EPACMTP simulates
subsurface fate and transport of contami-
nants leaching from the bottom of a waste
management unit and predicts concentra-
tions of those contaminants in a downgradi-
ent well. In making these predictions, the
model accounts for many complex processes13
that occur as waste constituents and their
transformation products move to and
through ground water. As leachate carrying
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 recep-
tor well, therefore, is  generally lower than
that in the leachate released from a waste
management unit.
   EPACMTP can determine the effect of fate
and transport through the unsaturated and
saturated zone on leachate constituent con-
centrations. In the unsaturated zone, it simu-
lates one-dimensional  vertical migration with
steady infiltration of constituents from the
waste management unit. In the saturated
zone, it simulates three-dimensional ground-
water flow (horizontal as well as vertical
spreading of a contaminant plume to incorpo-
rate infiltration from waste management
units).14 EPACMTP is a refined version of ear-
lier EPA fate and transport models. With these
improvements, the model considers  not only
the subsurface fate and transport of con-
stituents but also the formation and  the fate
and transport of transformation (daughter and
granddaughter) products. The model also can
simulate fate and transport of metals, taking
into account geochemical influences on the
mobility of metals. EPACMTP has been favor-
ably reviewed by EPA's Science Advisory
Board (SAB) which stated that it "represents
the state of the art for  such analyses."15
12For more detailed information on EPACMTP, consult the EPA's Industrial Waste Management Evaluation
Model (EPAIWEM) background materials.

13The processes addressed by the model include transport through the unsaturated zone, advection due to
ambient ground-water flow, hydrodynamic dispersion, first-order decay, linear and non-linear equilibrium
sorption of chemicals, decay reactions and transport of daughter and granddaughter products, effects of
water table mounding, and the duration of leachate release.

"This effect is called ground-water mounding underneath a waste unit.

"60 FR 66344, 66367 (December 21, 1995).


Protecting Ground Water—Assessing Risk Section
                      Another unique feature of EPACMTP is
                    that it can calculate the reduction in leachate
                    concentration expressed by a dilution/attenu-
                    ation factor (DAF). A DAF is defined as the
                    ratio of the expected leachate concentration to
                    the monitoring well concentration. The DAF
                    is then determined from the relationship:
                           DAF = -
                    where: G. is the leachate concentration (mg/L)
                          CMW is the monitoring well
                           concentration (mg/L).

                       The magnitude of a DAF reflects the capa-
                    bilities of the unsaturated and saturated zone
                    to retard or slow the transport of constituents
                    to a monitoring well. The lowest possible
                    value of DAF is one; a value of DAF=1  means
                    that there is no dilution or attenuation  at all;
                    the concentration at a monitoring point is the
                    same as that in the waste. High values of
                    DAF on the other hand correspond to a high
                    degree of dilution and attenuation. For any
                    specific site, the DAF depends on the interac-
                    tion of waste constituent characteristics (e.g.,
                    whether or not the constituent degrades or
                    sorbs), site-specific factors (e.g., geology),
                    and physical and chemical processes in the
                    subsurface environment.
                      EPACMTP was developed for regulatory
                    purposes. The analyses done with it are
                    based upon simplifying assumptions, and
                    data may not apply or may be inappropriate
                    for evaluating a specific waste management
                    unit. EPACMTP does not account for hetero-
                    geneities in the flow system, such as frac-
                    tures. It does not handle colloidal and immis-
                    cible (NAPL) transport. EPACMTP does not
                    account for multi-phase (vapor) flow; nor
                    does it account for reactive transport other
                    than sorption and decay. Thus the results of
                    the Tier 1 and Tier 2 modeling with EPAI-
WEM do not reflect these characteristics of a
particular waste management unit or loca-
tion. Waste management unit systems which
exhibit unique heterogeneities or have several
phases, such as colloids, and NAPLs should
be evaluated with a tool that is more appro-
priate to the particular characteristics  of the
facility. The assumptions used and potential
limitations of EPACMTP are discussed in the
Industrial Waste Management Evaluation Model
Background Document, EPACMTP Background
Document. U.S. EPA. 1996; and EPACMTP
Background Document for the Finite Source
Methodology. U.S. EPA. 1996.
Leachate Concentration Threshold Values
(LCTVs)                ;
   The Tier 1 and Tier 2 assessment tools rec-
ommend liner system designs or the appro-
priateness of land application based on calcu-
lated protective leachate thresholds for all
wastes in a unit. These LCTVs are the maxi-
mum leachate concentrations for which water
in a monitoring well is not likely to exceed
the given TKL. The LCTV accounts for waste
releases through a liner and dilution and
attenuation in the unsaturated and saturated
zone prior to reaching a monitoring well.
   The LCTV for a specific constituent is the
product of the TRL and the dilution and
attenuation factor (DAF):
        LCTV = DAF *  MCL
   or    LCTV = DAF *  HBN
   The adequacy of a liner system design is
evaluated by comparing the estimated waste
constituent leachate concentrations to the
LCTV The Tier 1 National Evaluation Model
is the most conservative and calculates
LCTVs using data collected on waste man-
agement units throughout the United States.16
LCTVs are generated for all unit types (i.e.,
landfills, waste piles, surface impoundments,
                    "For additional information on the nationwide data used in the modeling, see the IWEM Background


                                                                     Protecting Ground Water—Assessing Risk Section
and land application units). LCTVs are also
generated according to the type of liner
design (i.e., no-liner, single liner, or compos-
ite liner).17 At Tier 2, a user can input site-
specific data for 6 to 7 parameters  depending
on the type of waste management unit.

1. Tier I: National Evaluation
   The Tier 1 National Evaluation lookup
tables (see Appendix I) identify whether a pro-
posed liner design or land application is appro-
priate based on the constituent concentrations
present in the leachate from a waste manage-
ment unit. It allows you to compare the expect-
ed waste constituent concentrations  to the cal-
culated LCTVs in the lookup tables to help
make this determination. The LCTVs are the
maximum leachate concentration which does
not result in a ground-water concentration at a
downgradient well which exceeds a  given TRL.
The lookup tables do not require site-specific
data, only waste constituent concentrations,
and are simple and easy to use. Alternatively,
the EPAIWEM software contains a database
with the Tier 1 lookup tables.
   The lookup tables were developed from
EPACMTP modeling results. Using input
parameters from national waste and manage-
ment unit characteristics,18 EPACMTP  simu-
lated four waste management unit types —
landfills, surface impoundments, waste piles,
and land application units — and deter-
mined DAFs for 175 organic chemicals and
16 metals species. In developing the DAF
values, EPACMTP performed simulations on
a nationwide basis that reflect expected varia-
tions in site and hydrogeological conditions.
To account for this variability, the EPACMTP
fate and transport model is linked to a monte
carlo module which generates model input
parameter values  from the probability  distrib-
ution of each parameter. The monte carlo
method involves the repeated generation of
values  for the uncertain input variables
(drawn from the known distribution) and the
application of the fate and transport model to
generate a series of model responses (down-
gradient well concentrations). The generation
of random parameter values and fate and
transport simulation is repeated many times
to determine the probability distribution of
the downgradient well concentrations. The
DAF value is developed from this probability

   The LCTVs in the lookup table were deter-
mined by multiplying the EPACMTP 90th per-
centile DAF values with constituent-specific
TRLs. DAF values are determined by selecting
the monitoring well concentration for which
90 percent of the peak concentrations (or peak
30-year average concentration for carcinogens)
analyzed in a particular scenario are less than
the toxicity benchmark at the monitoring well.
In addition, several EPACMTP parameters
were fixed at conservative values. Specifically,
the monitoring well is assumed to be located
on the contaminant plume centerline. This
ensures that the highest constituent concentra-
tions in the plume would reach the monitoring
well. Similarly, the national evaluation model-
ing limited the potential distance to the moni-
toring well to 150 meters in order to monitor
         Information Needed to Use
           Tier 1 Lookup Tables
Waste management
unit types:
Waste constituent

Landfill, surface
impoundment, waste
pile, or land applica-
tion unit.

Constituents expected
in leachate.

Expected leachate
concentration of each
constituent or concen-
tration iii surface
impoundments or
waste to be applied.
17LCTVs are influenced by liner designs because of different infiltration rates.

18See the EPAIWEM Background Document for detailed information on parameter input values.


Protecting Ground Water—Assessing Risk Section
                    the performance of the liner system and to
                    avoid ground-water degradation, not because
                    of the presence of human receptors at that dis-
                    tance. For these reasons, the National
                    Evaluation LCTVs are relatively conservative.
                    How do I  use the Tier 1 lookup
                      As die first step in any ground-water risk
                    assessment, characterize the waste going into a
                    unit and determine the expected waste con-
                    stituent leachate concentrations. Estimate
                    leachate concentrations using knowledge of
                    waste generation processes and/or an analytical
                    leaching test appropriate to the circumstances,
                    such as the Toxicity Characteristic Leaching
                    Procedure (TCLP). For more information on
                    estimating a waste constituent concentrations
                    and appropriate leaching tests, refer to the
                    chapter on characterizing waste.
                      A comparison of the expected leachate con-
                    centrations to the LCTVs in the Tier 1 lookup
                    tables can help evaluate the type of liner need-
                    ed for the proposed waste management unit or
                    whether waste should be land applied. The
                    only input needed for this tool is the expected
                    waste constituent leachate concentration. Tier
                    1 lookup tables are available for each waste
                    management unit type. See Appendix I.
                  Alternatively, EPAIWEM has a database with
                  the lookup tables that can be used.
                  Tier 1 Notional Evaluation Example
                     The following example illustrates the Tier
                  1 process for evaluating a proposed liner
                  design for an industrial landfill. The example
                  assumes the expected leachate concentration
                  for toluene is 1.6 mg/L and styrene is 0.5
                  mg/L. In the Tier 1 process, the user would
                  compare the estimated constituent leachate
                  concentrations to the LCTVs in the National
                  Evaluation lookup tables summarized in
                  Table 3.
                     Table 4 shows the results of comparing
                  estimated constituent concentrations to the
                  LCTVs in the lookup tables. To determine
                  whether a proposed liner design is appropri-
                  ate, the example relied  on LCTVs based on
                  MCLs.  The lookup tables also allow compar-
                  isons to LCTVs based on HBNs.
                     Because EPA does not expect leachate con-
                  centrations from waste  management units
                  covered by this guidance to exceed 1,000
                  mg/L for a single constituent, the waste con-
                  stituent input values and all Tier 1 and Tier 2
                  LCTVs have been capped at a maximum
                  value of 1,000 mg/L. For any waste con-
                  stituent covered by the Toxicity Characteristic
                                                              Table 3
                                        Example National Evaluation Lookup Table for Landfills
                             MCL    HBN
                             (mg/L)   (mg/L)
No Liner/In-Situ Soil*
                                                                        LCTVs (mg/L)
                 Single Liner
Composite Liner
 based on
based on     based on   based on   based on  based on
  HBN         MCL       HBN i      MCL      HBN
                 * Section B of this chapter describes designing and installing liners of different types.


                                                                   Protecting Ground Water—Assessing Risk Section
                                           Table 4
                  Example National Evaluation Lookup Table Comparison Results
Concentration in
 Leachate (mg/L)
       Finding and Recommendation
Does not exceed no-liner/in-situ soil LCTY No-
liner/in-situ soil recommended
Exceeds no-liner/in-situ-soil and single liner
LCTVs. Composite liner recommended
 (TC) Rule (40 CFR Part 261), the LCTV is
 capped at the TC Rule regulatory level.
 Leachate concentrations above this level are
 considered to be characteristic hazardous
 waste.  If any waste constituent concentra-
 tions exceed the toxicity characteristic maxi-
 mum concentrations, the waste is considered
 RCRA hazardous and outside the scope of
 this guidance.

 What do the  results  mean  and
 how should I interpret them?
   If the expected leachate concentrations for
 all constituents are lower than the no-liner
 LCTVs, the proposed landfill does not need a
 liner to contain this waste.  If any constituent
 concentration is higher than the no-liner
 LCTV, then a single compacted clay liner or
 composite liner would be recommended for
 containment of the waste. If any concentra-
 tion is higher than the single-liner LCTV, then
 the recommendation is at least a composite
 liner.  If any concentration is higher than the
 composite liner, consider pollution preven-
 tion, treatment, or additional controls. For
 waste streams with multiple constituents,
 select the most protective liner that is speci-
 fied for any one constituent.
   Continuing with the example above, the
 recommendation is a composite liner because
 the styrene concentrations exceed the  single
                     liner threshold even though toluene did not.
                     Interpretation for land application is similar.  If
                     all the waste leachate concentrations are below
                     the threshold values in the Tier 1 lookup
                     tables, land-applying waste may be appropriate
                     for the site. It is still important, however, to
                     evaluate other land application factors outlined
                     in Section C of this chapter. These will still
                     influence whether land application is appropri-
                     ate and at what rate.  If the waste had several
                     constituents whose concentrations were less
                     than the land application threshold and one
                     constituent exceeding the land application
                     threshold, the recommendation is that land
                     application is not appropriate.
                        After conducting the Tier 1 National
                     Evaluation, consider the following steps.
                     •  Consider waste reduction/pollution pre-
                         vention, recycling, or treatment.  If the
                         waste has one or very few "problem"
                         constituents that call for a more stringent
                         and costly liner system (or which make
                         land application inappropriate), evaluate
                         pollution prevention, recycling, and
                         treatment efforts for those constituents.
                         Waste reduction, recycling, or treatment
                         options that before may have appeared
                         economically infeasible, may be
                         worthwhile if they can reduce the prob-
                         lem constituent concentration to levels
                         which result in a different liner recom-
                         mendation or make land application
                                                                                               7 A-17


Protecting Ground Water—Assessing Risk Section
                       appropriate.  After implementing these
                       measures, repeat the Tier 1 evaluation.
                       Based on the above example, pollution
                       prevention, recycling, or treatment mea-
                       sures could be used to reduce the styrene
                       concentrations below 0.46 mg/L so that a
                       single liner is recommended for the unit.
                       Consult the chapter on integrating pollu-
                       tion prevention, recycling, and treatment
                       for ideas and tools.
                    •  Implement recommendations.  This
                       option is the most straightforward.
                       Design the unit based on the liner
                       recommendations of the Tier 1 lookup
                       tables.  In the case of land application,
                       develop a land application system (after
                       evaluating other factors) if the design
                       lookup tables found land application to
                       be appropriate for all constituents. In
                       either case, consult the state to ensure
                       compliance with state regulations, which
                       could require more protective measures
                       than the Tier 1 lookup tables recom-
                    •  Conduct additional evaluations.
                       Conduct either a Tier 2 Location
                       Adjusted Evaluation or a Tier 3 site-
                       specific ground-water fate and transport
                       analysis as discussed below.
                       Figure 2 illustrates the basic steps for
                    using the Tier  1 lookup tables to deter-
                    mine whether  a liner design or land
                    application is appropriate.
                    2.   Tier 2: Location-Adjusted
                       The Tier 2 Location-Adjusted Evaluation is a
                    method in which a limited number of site-spe-
                    cific parameters are used to determine the
                    effect on the DAFs and the resulting LCTVs.
                    To facilitate this evaluation, EPA has developed
                    a set of artificial neural networks (one for each
                    waste management unit type) that utilizes
information concerning the waste management
unit and the hydrogeological conditions of the
site to determine the appropriate liner type for
containment of the wastes.  When calculating
LCTVs, a user can take into account a limited-
number of site-specific considerations without
having to run the EPACMTP or another
ground-water fate and transport model. As
with any ground-water assessment, discuss the
results of the Tier 2 evaluation with the state
and public before selecting a liner design or
land-applying waste.

What are the basic principles
and components  of the model?
   The Tier 2 artificial neural network pro-
gram that has been incorporated into a
stand-alone executable computer program
requires no specialized training in EPACMTP,
neural networks, or statistics. The Tier 2 tool
  What are neural networks?
  Neural networks are an information process-
  ing method. The revolutionary aspect of
  neural networks is their ability to learn com-
  plex patterns and/or be trained to adjust to
  new data. Neuralnetworks apply knowledge
  from past experience to new problems.
  Neural networks acquire, this knowledge by
  training on a specified set of combinations of
  input data. After the network has been
  trained and validated, the model may use
  data it has not seen previously for prediction,
  classification,  time series analysis or data seg-
  mentation. Unlike traditional statistical meth-
  ods, neural networks do not require assump-
  tions about the form or distribution of the
  data to analyze it.
  Additional information on neural networks is
  available in the Industrial Waste Management
  Facility Design Evaluation Model Background
  Document and on the Internet at


                                                                      Protecting Ground Water—-Assessing Risk Section
uses a multi-layer perception
(MLP) computing model and
software package as the
neural network for this
model. Using hundreds of
thousands of actual
EPACMTP realizations, the
neural network was
trained to estimate the
DAFs that EPACMTP gen-
erated based on changes in
specific combinations of
input parameters." The
neural network closely
matches the results that
EPACMTP generated.
   Using the neural-net-
work-estimated DAFs, the
software calculates corre-
sponding LCTVs  by multi-
plying the DAFs for each
constituent by its appropri-
ate TRL. The model will
then compare the expected
leachate concentrations to
these LCTVs and identify a
recommended liner for
landfills, surface impound-
ments, and waste piles. The
model can evaluate in-situ
soil, compacted clay liners,
and other liner designs for
which the resulting infil-
tration rate is known.
Figure 2. Process Diagram: Use of National Evaluation
                     Lookup Tables
                   Identify proposed WMU type.

               Estimate waste leachate concentration for
               all potential constituents expected to be
                      present in the waste.
              Compare expected leachate concentrations
                 to calculated LCTVs for all potential
 Implement liner
  and/or land
                          recycling, or
                  Proceed to Tier 2 location-adjusted
                evaluation or Tier 3 site-specific ground-
                  water fate and transport analyisis.
   In developing and training the neural net-
works, problems were encountered when the
extremes of the distributions were used as
input to the training. Training of the neural
networks was then limited to parameter val-
ues between the 10th and 90th percentile.
The composite liner infiltration rate assumed
in Tier 1 (3 x 10'5  for landfills) was outside
the 10th to 90th percentile range (0.024 to
0.45 m/yr for landfills), and thus the neural
networks were not trained using this value.
               Because the use of infiltration rates outside
               the range over which the neural networks
               were trained will result in significant error, the
               Tier 2 Location-Adjusted Evaluation does not
               explicitly address the composite liner scenario.

                  The proposed guidance still allows for
               assessment of the  composite liner scenario
               through the Tier 1 and Tier 3 evaluations. EPA
               is seeking comment on how to address inclu-
               sion of the composite liner scenario in the
               Tier 2 Location-Adjusted Evaluation. Options
"The Background Document and User's Guide discuss training the neutral network.


Protecting Ground Water—Assessing Risk Section
                    currently under consideration include: devel-
                    opment of multiple networks—one for low
                    infiltration rates and one for high infiltration
                    rates; and use of a Windows version of
                    EPACMTP (currently under development).
                    What input parameters most
                    strongly  influence Tier 2 results?
                       EPA conducted numerous analyses to
                    identify the input parameters that had the
                    greatest influence on the LCTVs generated by
                    the model. These "sensitive parameters" are
                    those that have the most significant effect on
                    model results given a relatively small change
                    in input values.
                        Waste management unit area. Area cov-
                        ered by the waste management unit in
                        square meters.
                        Infiltration, rate. Rate at which leachate flows
                        from the bottom of a waste management
                        unit (including any liner) into the unsatu-
                        rated zone beneath the waste management
                        unit. An area's rainfall intensity affects
                        infiltration rates as does the performance
                        of the liner system. Users can either input
                        infiltration rates directly or allow the Tier 2
                        program to estimate values for the no—
                        and single—liner scenarios based on the
                        unit's geographic location (or impoundment
                        characteristics for'surface impoundments).20
                        Depth, to the water table. The depth in
                        meters of the zone between the land sur-
                        face and the water table.
                        Aquifer thickness. The thickness of an
                        aquifer measured in meters.
                        Radial distance to monitoring well.
                        Distance in meters from the waste man-
                        agement unit to a monitoring well.
                                             •  Organic carbon distribution coefficient
                                                 (KOQ. A function of the nature of a sor-
                                                 bent (the soil and its organic carbon content)
                                                 and the properties of a chemical (the leach-
                                                 ate constituent). It is equal to the ratio of the
                                                 solid and  dissolved phase concentrations.
                                                 The higher the value of the distribution
                                                 coefficient, the higher the  adsorbed-phase
                                                 concentration, meaning the constituent
                                                 would be  less mobile. For metals, include
                                                 Kd, but if Kd is not known, software can
                                                 estimate if given the ground-water pH.
                                             •  Decay rate. The rate at which constituents
                                                 degrade or decay within an aquifer due to
                                                 chemical hydrolysis or biodegradation.
                                                 Measured in liters per year. The default
                                                 decay rate represents degradation from
                                                 chemical hydrolysis only, since biodegra-
                                                 dation rates are often strongly influenced
                                                 by site-specific factors.
                                                Because site-specific data for all of the sensi-
                                             tive parameters may not be available to a user
                                             of the software, the model contains "default"
                                             values for these parameters. The default values
                                             were derived from a number of sources, includ-
                                             ing a survey of industrial waste management
                                             units, a hydrogeologic database, water-balance
                                             modeling, and values reported in the scientific
                                             literature. The selection of default values is
                                             explained in the IWEM Technical Background
                                             Document. Use all site-specific data available,
                                             as the estimated leachate concentration values
                                             generated using primarily default data will
                                             tend to be conservative and may not accu-
                                             rately represent the conditions at the site.21

                                              How do I  use the model?
                                                The CD-ROM contairis the Tier 2 model.
                                             The User's Guide for the Industrial Waste
                                             Management Evaluation Model  provides com-
                                             plete installation instructions. The software
                                             will prompt a user to enter information on
"The software can estimate infiltration rates for surface impoundments if impoundment characteristics
such as ponding depth, thickness of sediment layer, and conductivity of sediment layer are input.

"A Tier 2 evaluation is not always less 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 Section
  Infiltration rate*
  Waste management unit area
  Depth to the water table
  Aquifier thickness
  Distance from receptor well
waste management unit type,
waste constituents, and
expected leachate concentra-
tions. In addition, it will
prompt a user to enter site-
specific values for known
selected parameters—those
that were identified as being
the most sensitive—replac-
ing the default values devel-
oped from the EPACMTP
input data. Figure 3 is an
example of some of the Tier
2 software screens. When
conducting a Tier 2 evalua-
tion, use documented and
realistic data for the site.
When changing default values, provide justi-
fications of the data sources and values as
necessary. Default values can be used if repre-
sentative of site-specific conditions. State
agencies and the public can review a loca-
tion-adjusted evaluation and may question
any unsupported assumptions.
Tier 2 Location-Adjusted Evaluation Example
   Continuing the example from Tier 1 for
toluene and styrene disposal in a proposed
landfill, consider the location-adjusted data
for the following sensitive  parameters.
   The Tier 2 evaluation will develop LCTVs
based on the location-adjusted data and com-
pare expected leachate concentrations to the
calculated LCTVs to determine a recommend-
ed liner system. The results recommend a
single liner system to dispose of toluene and
styrene under the location-adjusted condi-
tions.  The Tier 2 evaluation also provides a
detailed presentation of results which
includes a summary of inputs and accompa-
nying narrative, leachate concentrations, DAF
values, toxicity benchmarks (MCLs/HBNs),
chemical-specific parameters (KOC and decay
rate), and LCTVs. This allows a user to
understand how the LCTV values were calcu-
                          Table 5.
               Example Site-Specific Parameters
Site-Specific Data
Local climate: Madison, WI
Soil Type: fine-grained soil
 15,000 m2
*The Tier 2 model can calculate an infiltration rate for the liner
scenarios based on local climate and soil data.
                 lated and how the liner design recommenda-
                 tions were developed.  Because the detailed
                 results give the chemical-specific DAF value
                 for each liner scenario evaluated, a user can
                 calculate different LCTV values using differ-
                 ent TRLs, such as 0.1 times the MCL value or
                 10 times the HBN value.
                 What do the results mean and
                 how should  I interpret them?
                   As in the Tier 1 analysis, if the expected
                 leachate concentration is lower than the no-
                 liner LCTV, then the waste management unit
                 does not require a liner other than the native
                 soil. If the expected leachate concentration is
                 higher than the no-liner LCTV, then the rec-
                 ommendation is at least a single compacted
                 clay liner.  If the expected leachate concentra-
                 tion is higher than the single-liner LCTV, then
                 the recommendation is to consider pollution
                 prevention, treatment, or additional controls.
                 For waste streams with multiple constituents,
                 the recommendation is the most conservative
                 liner design identified for any one constituent.
                   As in the Tier 1 evaluation, consider inte-
                 grating pollution prevention, recycling, and
                 treatment practices. If you choose to follow


Protecting Ground Water—Assessing Bisk Section
                                           Figure 3. Example Input Screens for Tier 2 Model

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                                                               Protecting Ground Water—Assessing Bisk Section
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Protecting Ground Water—-Assessing Risk Section
                    the Tier 2 recommendations, consult with
                    the state to develop a more detailed design
                    plan for the waste management unit.
                    Alternatively you can undertake a compre-
                    hensive assessment to more accurately
                    reflect site-specific conditions. See Tier 3:
                    Site-Specific Ground-Water Fate and
                    Transport Analysis, for further information.
                       In addition to the Tier 2: Location-
                    Adjusted Evaluation  model, other fate  and
                    transport-models have been developed that
                    incorporate location-specific considerations,
                    such as the American Petroleum Institute's
                    (API's) Graphical Approach for Determining
                    Site-Specific Dilution-Attenuation Factors.22 API
                    developed its approach to calculate 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 attenuation 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 plume's geometry. The user can
                    read other necessary factors off graphs pro-
                    vided 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
                    constituent leaching, biodegradation of con-
                    stituents, or site-specific dispersivity values.
                    At either level of analysis, the calculation
                    results in a DAE This approach is not appro-
                    priate for all situations; it should not be used
                    to estimate chemical concentrations in active
                    ground-water supply wells or to model very
                    complex hydrogeologic settings, such as frac-
                    tured rock. Consult with the state to discuss
                    the applicability of the API approach or any
                    other location-adjusted model prior to use.
                                             Why is it important to use a qualified

                                             •   Fate and transport modeling can be
                                                 extremely complex.
                                             •   Incorrect fate and transport modeling can
                                                 result in a liner system' that is not suffi-
                                                 ciently protective or an inappropriate
                                                 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.
                                              3.  Tier 3: Site-Specific Ground-
                                                  Water Fate and Transport
                                                Site-specific ground-water fate and trans-
                                              port analysis is the most detailed method for
                                              estimating potential risk to ground water and
                                              evaluating alternative liner designs or applica-
                                              tion rates. 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, consider a site-specific risk
                                              assessment.23 Consult with the state and use a
                                              qualified professional experienced in ground-
                                              water modeling if appropriate. Talk to state
                                              officials and/or appropriate trade associations
                                              to solicit recommendations for a good consul-
                                              tant to perform the analysis.

                                              How to select a site-specific
                                              ground-water fate and transport
                                                Estimating exposure concentrations in
                                              ground water using models can be a complex
                                              task due to the many physical and chemical
"A copy of API's user manual can be found on the CD-ROM. 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.

:3For example, if the depth to ground water at the site is over 250 feet, use of the Tier 2 Location-adjusted
Evaluation tool may not be appropriate because the model is based on data from units with shallower
depths to ground water.


                                                                    Protecting Ground Water—Assessing Risk Section
processes that affect transport and transfor-
mation of constituents in ground water.
Hundreds of different models have been
developed to simulate the fate and transport
of constituents in ground water.  Proper
selection and application of ground-water
models requires a thorough understanding of
the waste and  the physical, chemical, and
hydrogeologic characteristics of the site.
   In addition  to evaluating whether a model
will adequately address site characteristics,
ask the following questions to ensure that the
model will provide accurate, meaningful
•   What is the source of the model and how
    easy is it to obtain? Is it a proprietary
•   Are documentation and user's manuals
    available for the model  and, if so, are they
    well-written and easy to use?
•   Has the  model been verified against ana-
    lytical solutions and other models and, if
    so, are the test cases available so that your
    consultant can test the model on his/her
    computer system?
•   Has the  model been validated using field
   As with all modeling, consult with the state
before investing significant resources in a site-
specific analysis. The state may have a list of
preferred models and may be able to help
plan the fate and transport analysis.
   EPA's report Selection Criteria for
Mathematical Models Used in Exposure
Assessments:  Ground-Water Models lists a num-
ber of criteria to evaluate before selecting a
ground-water fate and transport model. It also
provides a primer on ground-water flow. This
document is available through the National
Technical Information Service, Springfield,
Virginia, 22161, phone: 800 553-6847,
Internet: <www.ntds.gov/home.htm>.  The
American  Society for Testing and Materials
 (ASTM) also provides guidance for conduct-
 ing modeling and a listing of guidance materi-
 al can be found in the sidebar.
   Examples of questions to answer before
 selecting a model are provided below.
 •  Does a confined aquifer, an unconfined
    aquifer, or both need to be simulated?
 •  Does the ground water flow through porous
    media, fractures, or a combination of both?
 •  Is it necessary to  simulate three-dimen-
    sional flow or can the dimensionality be
    reduced without  significantly reducing
 •  Is there a single or are there multiple
    hydrogeologic layers to be simulated?
 •  Is (are) the hydrogeologic layer(s) of
    constant or variable thickness spatially?
 •  Does the model simulate dispersion?
 •  Does the model simulate sorption?
 •  Does the model simulate first, second-
    order, or other-order decay?
 •  Does the model simulate density effects
    related to changes in temperature and
What do the results of a site-
specific fate and transport analy-
sis mean?
  A site-specific analysis should, at a mini-
mum, provide estimated leachate concentra-
tions at specified downgradient points for a
proposed liner design. For landfills, surface
impoundments, and waste piles, compare
these concentrations to appropriate MCLs,
health-based standards, and/or state stan-
dards.  For land application units, if a waste
leachate concentration is below the values
specified by the state, land application may be
appropriate.  Conversely, if a leachate concen-


• Pro;
Protecting Ground Water—Assessing Risk Section
                       tration is above state-specified values, land
                       application may not be, protective of the
                       ground water.
                          A well-executed, site-specific analysis can
                       be a useful instrument to anticipate and avoid
                       potential risks. A poorly-executed, site-spe-
                       cific analysis, however, could over-or under-
                       emphasize risks, possibly leading to adverse
                       human health and environmental effects, or
                       costly cleanup liability, or could overempha-
                       size risks, possibly leading to the unnecessary
                       expenditure of limited resources. Share the
                       model,  if possible, and the results of the final
                       analyses, including input and output parame-
                       ters-and key assumptions, with key stake-
                       holders. The chapter on building partner-
                       ships provides a more detailed description of
                       activities to keep the public informed and
                                                                     Table 6 provides a brief description of five
                                                                  ground-water fate and transport models.
                                                                  These descriptions are included in EPA's
                                                                  Ground-Water Modeling Compendium (see
                                                                  Resources at the end of this chapter for a
                                                                  complete citation).
                       a ground-water fete and transport model?
                       The following list of EPA resources can help
                       select an appropriate model.
                       •  Ground Water Modeling Compendium,
                          Second Edition (EPA 1994)
                       •  Assessment Framework for Ground-
                          Water Modeling Applications (EPA 1994)
                       •  Selection Criteria for Mathematical
                          Models Used in Exposure Assessments:
                          Ground-Water Models (EPA 1988c).
                       •  Superfund Exposure Assessment Manual
                          (SEAM—EPA 1988b).
                       •  Exposure Assessment Methods
                          Handbook (EPA 19890.
                       •  EPA's Center for Exposure Assessment
                          Modeling (CEAM—Environmental
                          Research Laboratory; Athens, Georgia).
                       •  EPA regional offices.


                                      Protecting Ground Water—-Assessing Risk Section
 ASTM Ground-Water Modeling Standards

 The American Society for Testing and Materials (ASTM), Section D-
 18.21.10 concerns subsurface fluid-flow (ground-water) modeling.
 The ASTM ground-water modeling section is one of several task
 groups funded under a cooperative agreement between USGS and
 EPA to develop consensus standards for the environmental industry
 and keep the modeling community informed as to the progress-;
 being made in development of modeling standards.

 The standards being developed by D-18,21,10 are "guides" in
 ASTM tenninoiogy, which means that the content is analogous to.
 that of EPA guidance documents. The ASTM modeling guides are
 intended to document the state-of-the-science related to various
 topics in subsurface modeling.       .      : •  ;: ,.-..•'.•"---

 The foEowing standards have been developed by D-i8;2UO and
: passed by ASTM. They can be purchased from ASTM by;callmg /
 610 832-9585-  Seethe ASTM web site <www,astm.oig> to. order  ,
 or browse for publications.     .                 .    :      :-'

 D-5447 Guide for Application of a Ground-Water Flow Model to a
 Site-Specific Problem    .:                            '  ;

 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 Flow 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 How Model
 Application                .             •-••...,.

 A compilation of most of the current modeling and aquifer testing
 standards also can be purchased. The tide of the publication is
 ASTM Standards on Analysis of Hydrologic Parameters and Ground
 Water Modeling, publication number 03-418096-38. For more
 information by e-mail, contact servke@astm.org.


Protecting Ground Water—Assessing Risk Section
                       Model Name
                                                                 Table 6.
                                     Example Site-Specific, Ground-Water Fate and Transport Models
AT123D is a generalized analytical transient, one- two-, and/or three-
dimensional computer code developed for estimating the transport of
chemicals in a confined aquifer system with uniform flow. The model
handles various source configurations (including point source, line source,
and areal source) and release characteristics. The transport mechanisms
include advection, longitudinal as well as horizontal and vertical trans
verse hydro-dynamic dispersion, diffusion, linear adsorption, and first-
order decay/degeneration and chemical losses to the atmosphere. The
model calculates concentration distribution in space and time using
Green's function.
The model was developed by Oak Ridge National Laboratory. For more
information and/or to obtain a copy of this model, contact:
       International Ground Water Modeling Center (IGWMC)
       Colorado School of Mines
       Golden, Colorado 80401-1887
       Phone: 303 273-3103 (General Questions, Sales)
       Phone: 303 273-3105 (Technical Support)
       Internet: <www.mines.edu^gwmo
       igwmc@mines.edu  (General Questions, Sales)
       gwtech@mines.edu (Technical Support)
 MOC is a ground-water flow and mass transport model. It provides
 capabilities for two dimensional simulation of non-conservative solute
 transport in aquifers. It computes changes in time in the spatial concen-
 tration distribution caused by convective transport, hydrodynamic, disper-
 sions,  mixing or dilution from recharge, and chemical reactions. The
 chemical reactions include first-order sorption irreversible rate reaction
 (e.g., radioactive decay), equilibrium-controlled sorption with linear,
 Freundlich or Langmuir isotherms, and monovalent and/or divalent ion-
 exchange reactions. It uses the method of characteristics followed by an
 explicit procedure to solve the transport equation. MOC uses a subgrid
 of the flow grid for simulation of containment transport.
 The model was developed by the U.S. Geological Survey.  For more infor-
 mation and/or to obtain a copy of this model,  contact IGWMC using the
 information described above.                     :


                                                                      Protecting Ground Water—-Assessing Risk Section
                                         Table 6.
          Example Site-Specific, Ground-Water Fate and Transport Models (cont.)
Model Name
MODFLOW is a model for steady state and transient simulation of two-
dimensional, quasi three-dimensional, and fully three-dimensional saturat-
ed flow problems in confined and unconfined aquifers. It calculates flow
rates and water balances.  The model includes flow towards wells, dirough
riverbeds, and into drains.
For more information and/or to obtain a copy of this model, contact
IGWMC using the information described above.
MT3D is a three-dimensional contaminant transport model using a hybrid
method of characteristics. Two numerical techniques are provided for the
solution of the advective-dispersive reactive solute transport equation: the
method of characteristics (MOC) and die modified method of characteris-
tics (MMOC). The MMOC method overcomes many of the traditional
problems with MOC, especially in 3D simulations, by directly tracking
nodal points backwards in time and by using interpolation techniques.
MT3D selectively uses the MOC or the  MMOC technique dependent on
the problem at hand. The transport model is so structured that it can be
used in conjunction widi any block-centered finite difference flow model
such as the USGS MODFLOW model.
The model was developed by S.S. Papadopulos & Associates, Inc. For
more information and/or to obtain a copy of this model, contact:
Center for Subsurface Modeling Support
R.S. Kerr Environmental Research Laboratory
P.O. Box 1198
Ada, OK 74820
Phone: 405 332-8800
RANDOM WALK/TRANS is a numerical model to simulate two-dimen-
sional steady or transient flow and transport problems in aquifers under
water table and/or confined or leaky confined conditions. The flow is
solved using a finite difference approach and the iterative alternating direc-
tion implicit method. The advective transport is solved with a particle-in-
cell method, while the dispersion is analyzed with the random walk
This model was developed by Illinois State Water Survey. For more infor-
mation and/or to obtain a copy of this model, contact IGWMC using die
information described above.


Protecting Ground Water—Assessing Risk Section




                Action  Items for Assessing Risks  to Ground  Water
Review the risk characterization tools recommended by this chapter.

Characterize the waste in accordance with the recommendations of the chapter on charac-
terizing waste. Obtain leachate concentrations for all relevant waste constituents.

Understand and use the Tier 1: National Evaluation lookup tables, if appropriate.

If appropriate, understand and use the Tier 2: Location-adjusted Evaluation.

If appropriate, understand and use a site-specific ground-water fate and transport model.


                                                                Protecting Ground Water—Assessing Risk Section
American Petroleum Institute. Graphical Approach for Determining Site-Specific Dilution-Attenuation
Factors: Technical Background Document and User Manual. API Publication 4659.

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

ASTM. 1993.  D-5490 Guide for Comparing Ground-Water Flow Model Simulations to Site- Specific

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

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.

Bonaparte, R., J.P. Giraud, and B.A. Gross.  1989. "Rates of Leakage Through Landfill Liners,"
Proceedings of Geosynthetic '89 Conference, Volume 1.


Protecting Ground Water—Assessing Risk Section
                                         Resources  (cont.)
           Boulding, R. 1995. Soil, Vadose Zone, and Ground-Water Contamination: Assessment,
           Prevention, and Remediation.

           Giroud, J.R, K. Badu-Tweneboah.  1992.  "Rate of Leakage Through a Composite Liner Due to
           Geomembrane Defects," Journal of Geotextiles and Geomembranes, Volume 11.

           Giroud, J.P., and R. Bonaparte. 1989.  "Leakage Through Liners Constructed with
           Geomembranes: Part I Geomembrane Liners," Journal of Geotextiles and Geomembranes,
           Volume 8.

           Giroud, J.P., and R. Bonaparte. 1989.  "Leakage Through Liners Constructed with  '
           Geomembranes: Part II Composite Liners," Journal of Geotextiles and Geomembranes, Volume 8.

           Lee, C. 1992. Environmental Engineering Dictionary, 2d. Ed.

           Sharma, H., and S. Lewis. 1994. Waste Containment Systems, Waste Stabilization, and

           Speidel, D,, L. Ruedisili, and A. Agnew.  1988.  Perspectives on Water: Uses and Abuses.

           U.S. EPA.  1998. Industrial Waste Management Evaluation  Model Technical Background

           U.S. EPA.  1998. The User's Guide for the Industrial Waste Management Evaluation Model.

           U.S. EPA.  1996. Composite Model for Leachate Migration with Transformation Products.

           U.S. EPA.  1996. EPACMTP Background Document.

           U.S. EPA.  1996. EPACMTP Background Document for the Finite Source Methodology.

           U.S. EPA. 1994. Assessment Framework for Ground-Water Modeling Applications. EPA500-B-

           U.S. EPA  1994. Ground Water Modeling Compendium, Second Edition. EPA500-B-94-003.


                                                           Protecting Ground Water—Assessing Bisk Section
                             Resources  (cont.)
U.S. EPA. 1991.  Seminar Publication: Site Characterization for Subsurface Remediation. EPA625-4-

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.



              Part IV
     Protecting Ground Water

        Chapter 7: Section B
   Designing and Installing Liners
  Technical Considerations for Surface
Impoundments, Landfills, and Waste Piles


I.   In-Situ Soil Liners    ^   ;   7B'1

II.  Single Liners  !   ;7B'2
    A. Compacted Clay Liners    ;   7B~2
    B. Geomembranes or Flexible Membrane Liners     7B-10
    C Geosynthetic Clay Liners  t   7B~17

III. Composite Liners   •   7B~22

IV. Double Liners (Primary and Secondary Lined Systems)     ,   7B-23

V. Leachate Collection and Leak Detection Systems   ;   7B-24
    A. Leachate Collection System   .••.-••••.  •••••   —7B-25
    B. Leak Detection System    7B-29
    C. Leachate Treatment System    !   7B-29

VI. Construction Quality Assurance and Quality Control  •   7B-30
    A. Compacted Clay Liner Quality Assurance and Quality Control   7B-32
    B. Geomembrane Liner Quality Assurance and Quality Control  ,   7B-33
    C. Geosynthetic Clay Liner Quality Assurance and Quality Control    7B-34
    D. Leachate Collection System Quality Assurance and Quality Control     7B-34

 Action Items for Lined Units (Landfills, Waste Piles, and Surface Impoundments)    7B-36

 Resources  r   •7B-37

   Figure 1: Water Content for Achieving a Specific Density 7B-7
   Figure 2: types of Footed Rollers    •   7B~9
   Figure3: Four Variations of GCL Bonding Methods  ,   7B-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  Surface  Impoundments,
                  Landfills, arid  Waste  Piles

        Employ liner systems where needed to protect ground water
        from contamination. Select from clay liners, synthetic liners,
        composite liners, leachate collection systems, and leak detec-
        tion 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 liner
           system chosen, unit design can
           proceed. A critical part of this
           design for landfills, waste piles,
and surface impoundments is the liner system.
The liner system recommendations in this guid-
ance 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 the discussion
in designing a land application program section
of this chapter.)  During liner system design,
work with state  agencies to ensure considera-
tion of any applicable liner system require-
ments, recommendations, or standard practices
the state may have. In this part of the chapter,
sections I though IV discuss four liner
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

  For the purpose of this guidance, in-situ
soil liners refer to simple, excavated areas or
impoundments, without any additional engi-
neering controls. The ability of natural soils to
reduce the concentration of constituent levels
through dilution and attenuation may provide
sufficient protection when the initial con-
stituent levels in the waste stream are very low,
when the wastes are inert, or when the hydro-
geologic setting affords sufficient protection.

What are the recommendations
for in-situ soils?
  The soil below and adjacent to a waste man-
agement unit should be suitable for construc-
tion. It should provide a firm foundation for
the waste. Due to the low risk associated with
wastes being managed in these units, no liner
may be necessary; however, it is still helpful to
review the recommended location considera-
tions and operating practices for the unit.


Protecting Ground Water—Designing and Installing Liners
                    What technical issues should be
                    considered with the use of in-situ
                      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
                    •  The location where the unit will be sited;
                    •   The potential to recompact existing soils.
                    Potential instability can occur in the founda-
                    tion soil, if its-load-bearing capacity and resis-
                    tance to movement or consolidation are insuf-
                    ficient to support the waste. The ground-water
                    table or a weak soil layer also may influence
                    the stability of the unit. 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  vertical incli-
                    nation. Follow common sense operating prac-
                    tices and ensure that any wastes to be man-
                    aged on in-situ soils will not inappropriately
                     interact with the soils. When using in-situ
                     soils, refer to the chapter on considering the
                     site. Selecting an appropriate location will be
                     of increased importance, since the added bar-
                     rier of an engineered liner will not present.
                     Because in-situ soil may have non-homoge-
                     neous material, root holes, and cracks, its per-
                     formance can be improved by scarifying and
                     compacting the top portion of the in-situ nat-
                     ural soils.
II.    Single Liners
  If the risk evaluation recommended the use
of a single liner, determine the type of single
liner system most appropriate for the site. The
discussion below addresses three types of sin-
gle liner systems: compacted clay liners,
geomembrane liners, and geosynthetic clay
liners. Determine which material, or combina-
tion of materials, protects human health and
the environment based on the cost of these
materials for the unit.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 may be
excavated from onsite, locations known as bor-
row pits. Alternatively, if on-site soils do not
contain sufficient clay, clay materials can be
hauled from off-site 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,
 implement effective quality control methods
 emphasizing soil investigations and construc-
 tion practices. Three objectives 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 compacted, and (3) the
 completed liner is properly protected before,
 during, and after construction. Quality assur-
 ance and quality control are discussed in
 greater detail in section VI.
                      '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 Installing Liners
 What are the thickness and
 hydraulic conductivity recom-
 mendations for compacted clay
   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"8
 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 consid-
 ered in the design  of a  compact-
 ed  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.
Soft Properties
   Minimizing hydraulic conductivity is the
primary goal in constructing a soil liner.
Consider water content, plasticity characteris-
tics, percent fines, and percent gravel, as
these properties affect the soil's ability to
achieve a specified hydraulic conductivity.

   Hydraulic Conductivity. Select compacted
   clay liner materials so that remolding and
   compacting of the materials will produce a
   low hydraulic conductivity. Factors influ-
   encing the hydraulic conductivity at a par-
   ticular site include: the degree of com-
   paction, compaction method, type of clay
   material used, soil moisture content, and
   density of the soil during liner construc-
   tion. 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 amend-
  ments,  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 mate-
  rials.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 Assurance and Quality Control for
  Waste Containment Facilities (EPA600-R-93-
2ASTM D-5084, Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous
Materials Using a Flexible Wall Permeameter.

3ASTM D-698, Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12 400 ft-
Ibf/ft3  (600 kN-m/m3)).


Protecting Ground Water—Designing and Installing Liners
                       Plasticity Characteristics. Plasticity charac-
                       teristics describe a material's ability to
                       behave as a plastic or moldable material.
                       Soils containing clay are generally catego-
                       rized as plastic. Soils that do not contain
                       clay are non-plastic and typically consid-
                       ered unsuitable 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 content over which a soil
                        exhibits plastic behavior. 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 may form
                        around these clumps allowing leachate to
                        flow through the material at a higher rate.
                        Soil plasticity indices typically range from
                        10 percent to 30 percent. Soils with a plas-
                        ticity index greater than 30 percent are
                        cohesive, sticky, and difficult to work with
                        in the field. Common testing methods for
                        plasticity characteristics include the meth-
                        ods specified in ASTM D-4318, also
                        known as Atterberg limits tests.4

                        Percent Fines and Percent Gravel. Typical
                        soil liner materials contain at least 30 per-
                         cent fines and may contain up to 50 per-
                         cent gravel, by weight. Common testing
                         methods for percent fines and percent
                         gravel are specified in ASTM D-422, also
                         referred to as grain size distribution tests.3
Fines refer to silt and clay-sized particles.
Soils with less than 30 percent fines may
be worked to obtain hydraulic conductivi-
ties below 1 x lO'7 cm/sec-(4 x 10'8
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, relative-
ly large amounts of gravel, up to 50 per-
cent by weight, can be uniformly mixed
with clay materials without significantly
increasing the hydraulic conductivity of
the material. Clay materials fill voids creat-
ed between gravel particles, thereby creat-
ing a gravel-clay mixture with a low
hydraulic conductivity. Creating a uniform
mixture of clay and gravel, where clay can
fill in gaps, is more critical than the actual
gravel content of the mixture, as long as
the percent gravel in a compacted clay
mixture remains below 50 percent.

Pay close attention to the percent gravel in
cases where a compacted clay liner func-
tions as a bottom layer to  a geosynthetic,
as gravel can cause puncturing in geosyn-
thetic materials. Controlling the maximum
 particle size and angularity of the gravel
 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 preferen-
 tial flow paths. To help prevent the devel-
 opment of preferential pathways and an
 increased hydraulic conductivity, use soil
 liner materials where the soil particles and
 rock fragments are less than 3/4 inch in
                      '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
Interactions With Waste

   Waste placed in a unit may interact with
compacted clay liner materials, thereby influ-
encing soil properties such as hydraulic con-
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 may
be dissolved by acids, and silica may be dis-
solved by bases. While some plugging of soil
pores by dissolved minerals may lower
hydraulic conductivity in the short term, the
creation of piping and channels over time
may lead to an increased hydraulic conduc-
tivity in the long term.  The interaction of
waste and clay materials may also cause the
creation of positive ions, or cations. The pres-
ence of cations such as sodium, potassium,
calcium, and magnesium may change the clay
structure, thereby influencing the hydraulic
conductivity 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,
develop a good understanding of the compo-
sition of the waste that will be placed in the
waste management unit. EPA's Method 9100,
in publication SW-846,  measures the
hydraulic conductivity of soil samples before
and after exposure to permeants.6
Locating and Testing Material
   Although the selection process for com-
pacted clay liner construction materials may
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. In
addition, test a representative sample of soil
to determine material properties such as plas-
ticity characteristics, percent gravel, and per-
cent fines. To confirm the suitability of the
materials once construction begins, consider
requesting that representative 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 pro-
vides the materials, locating an appropriate
on-site borrow pit is no longer necessary. In
addition to the tests performed on the materi-
al, a qualified inspector should 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 consid-
ered in the construction  of a
liner and the operation of a
   Develop test pads to demonstrate con-
struction techniques and material perfor-
mance on a small scale. During unit construc-
tion and operation, some additional factors
influencing the performance of the liner
include: preprocessing, subgrade preparation,
method of compaction, and protection
against desiccation and cracking. Repeat all
the steps, from preprocessing through protec-
tion against desiccation and cracking, for
each lift, or layer of soil.
6SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods.


Protecting Ground Water—Designing and Instating Liners
                    Test Pads
                      Preparing a test pad for the compacted clay
                    liner helps verify that the materials and meth-
                    ods proposed will yield a liner that meets the
                    desired hydraulic conductivity. A test pad also
                    provides an opportunity to demonstrate the
                    performance of alternative materials or meth-
                    ods of construction. A test pad should be con-
                    structed with the soil liner materials proposed
                    for a particular project, using the same prepro-
                    cessing procedures, compaction equipment,
                    and construction practices proposed for the
                    actual liner. A complete discussion of test pads
                    (covering dimensions, materials, and construc-
                    tion) can be found in Chapter 2 of EPA's 1993
                    technical guidance document Quality Assurance
                    and Quality Control for Waste Containment
                    Facilities (EPA600-R-93-182). A discussion of
                    commonly used methods to measure in-situ
                    hydraulic conductivity is also contained in that
                       Although some liner materials may be
                    ready for use in construction immediately
                    after they are excavated, many materials will
                    require some degree of preprocessing.
                    Preprocessing methods include: water content
                    adjustment, removal of oversized particles,
                    pulverization of any clumps, homogenization
                    of the soils, and introduction of additives,
                    such as bentonite.
                       Water Content Adjustment. For natural
                       soils, the degree  of saturation  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 optimum tend to have a relatively
                       high hydraulic conductivity. Soils compact-
                       ed at water contents 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 max-
imum dry density. The minimum dry den-
sity typically falls in the range of 90-95
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, 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 content
range because it is easier to  add water to the
clay soil than to  remove it. Thus, if precipi-
tation occurs during construction of a site
which is being placed at the lower end of
the required water content range, the addi-
tional water may 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
percent, any additional moisture will be
excessive, resulting in water content over 28
percent and making the 90 percent maxi-
mum dry density unattainable. Under such
conditions constractiqn should halt while
the soil is aerated and excess moisture is
allowed to evaporate.

Removal of Oversized Particles.
Preprocessing clay materials, to remove
cobbles or large stones that exceed the
maximum allowable particle size, can
improve the soil's compactibility and pro-
tect any adjacent geotnembrane from punc-
ture. A recommended  maximum allowable
particle size is less than 3/4 inch for com-
paction considerations. If a geomembrane
will be placed over the compacted clay,


                                                             Protecting Ground Water—Designing and Installing Liners
                           Figure 1.
         Water Content for Achieving a Specific Density
 sS  100  -
                          Water Conjent (w>,%
Source: U.S. EPA. 1988. Lining of Waste Containment and Other
Impoundment Facilities. EPA600-2-88-052.
  only the upper lift of clay needs to address
  concerns regarding puncture resistance.
  Observation by quality assurance and qual-
  ity control personnel is the most effective
  method to identify areas where oversized
  particles 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 com-
  pacted. In wet clay, clods are less  of a con-
  cern 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 common 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 per-
                 cent, can be added to
                 sand or other noncohe-
                 sive soils to increase the
                 cohesion of the material
                 and reduce hydraulic con-

                 Sodium bentonite is a
                 common additive used to
                 amend soils.  However,
                 this additive is  vulnerable
                 to degradation  as a result
                 of contact with certain
                 chemicals and waste
                 leachates. Calcium ben-
                 tonite, a more permeable
                 material than sodium
bentonite, is another common additive used
to amend soils. Approximately twice as
much calcium bentonite is needed to
achieve a hydraulic conductivity compara-
ble 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 con-
tent, bentonite content, and particle distrib-
ution need to be controlled. Other materials
that can be used as soil additives  include
lime cement and other clay minerals, such
as atapulgite. It may be difficult to mix


Protecting Ground Water—Designing and Instating Liners
                      additives thoroughly with cohesive soils, or
                      clays; the resultant mixture may not achieve
                      the desired level of hydraulic conductivity
                      throughout the entire liner.
                   Subgrade Preparation
                      Ensure that the subgrade on which a com-
                   pacted clay liner will be constructed is prop-
                   erly prepared. When a compacted 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 remov-
                   ing water from the native soil to obtain a
                   specified firmness. Alternatively, in some
                   cases, the compacted clay liner can  be placed
                   on top of a geosynthetic material, such as a
                   geotextile.  In such cases, subgrade prepara-
                   tion involves ensuring the smoothness of the
                   geosynthetic on which the clay liner will be
                   placed and the conformity of the  geosynthetic
                   material to the underlying material.
                      The main purpose of compaction is to
                    densify 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 compactor, the charac-
teristics of any feet on the drum, and the
weight of the roller per unit length of
drummed surface. Heavy, compactors, weigh-
ing 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 lin-
ers. For bentonite-soil mixtures, a footed
roller may not be appropriate.  For these mix-
tures, where densification of the material is
more important than kneading or remolding
it to meet low hydraulic conductivity specifi-
cations, a smooth-drum roller  or a rubber-
tired roller may produce  better results. Figure
2 depicts two types of footed rollers, a fully
penetrating footed roller  and a partially-pene-
trating footed roller.
   For placement of liners on side slopes,
consider the angle and length of the slope.
Placing continuous lifts qn a gradually
inclined  slope will provide better continuity
between the bottom and sidewalls of the
liner. Since continuous lifts may be impossi-
ble to construct on steeper slopes due to the
difficulties of operating heavy compaction
equipment on these slopes, materials may
need to be placed and compacted in horizon-
tal lifts.  When sidewalls are compacted 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,  the thickness of the horizontal lift is
often greater than the thickness specified, in
the design. In such cases, consider trimming
soil material from the constructed side  slopes
and sealing the trimmed surface using a
sealed drum roller.


                                                             Protecting Ground Water—Designing and Installing Liners
                              Figure 2. Types of Footer Rollers
                                                        Rotter with
   Roller with
Fully Penetrating
                                   Loose lift of So8

     Fully Ptrwtreang Fwt on Holltf
     Compact Saw oj New, IAOM Lift
     of Soil Into Surfac* et OW. Pravtoudy
                                         Parity Pgn«ratfng F«et on Roltor Do
                                         Not Exttnd to BOM of N«w, LOOM
                                         Uftef Soil and Do Not Compact Now
Source: U.S. EPA. 1993. Technical Guidance Document: Quality Assurance and Quality Control
For Waste Containment Facilities. EPA600-R-93-182.
   It is common for contractors to use several
   different types of compaction equipment
   during liner construction. Initial lifts may
   need the use of a footed roller to fully pen-
   etrate a loose lift. Final lifts also may need
   the use of a footed roller for compaction,
   however,  they may be formed  better by
   using a smooth roller after the lift has been
   compacted to smooth the surface of the lift
   in preparation for placement of an overly-
   ing geomembrane.

   Number, of Passes. The number of passes
   made by a compactor over clay materials
   can influence the overall  hydraulic con-
   ductivity  of the liner. The minimum num-
   ber of passes that is reasonable depends on
   a variety of site-specific factors and cannot
   be generalized. In some cases,  where a
   minimum coverage is specified, it may 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

                                An equipment pass may be defined as one
                                pass of the compaction equipment or as
                                one pass of a drum over a given area of
                                soil. Clearly define what is meant by a pass
                                in any quality assurance or quality control
                                plans. It does not matter which definition
                                is agreed upon, as long as the definition is
                                used consistently throughout the project.

                                Lift Thickness. Determine the appropriate
                                thickness (as measured before compaction)
                                of each of the several lifts that will make
                                up the clay liner. The initial thickness 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
                                sufficient to allow homogenous bonding  -
                                between subsequent lifts. Loose lift thick-
                                nesses typically range between 13 and 25


Protecting Ground Water—Designing and Installing Liners
                      cm (5 and 10 in.). Factors influencing lift
                      thickness are: soil characteristics, com-
                      paction equipment,  firmness of the foun-
                      dation materials, and the anticipated com-
                      paction necessary to meet hydraulic con-
                      ductivity 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 recom-
                      mended methods exist for preparing prop-
                      er bonds. The first method involves knead-
                      ing, or blending the new lift with the pre-
                      viously 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 quali-
                      ty of the bond. A second method involves
                      using a disc harrow or similar equipment
                      to scarify, or roughen, and wet the top inch
                       of the recently placed lift, prior to placing
                       the next lift.
                     Protection Against Desiccation and Cracking
                       Consider how to protect compacted clay
                     liners against desiccation and freezing during
                     and after construction. Protection against des-
                     iccation is important, because clay soil
                     shrinks as it dries. Depending on the extent
                     of shrinkage, it may crack. Deep cracks,
                     extending through more than one lift, may
                     cause problems. 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
minimize the movement of water into or out
of the compacted material. Another option is
to wet the clay periodically in a uniform
manner; however, make sure to avoid creat-
ing areas of excessive wetness. A third mea-
sure involves covering compacted clay liner
materials with a sheet of white or clear plastic
or tarp to help prevent against desiccation
and cracking. The cover should be weighted
down with sandbags or other material to
minimize exposure of the underlying materi-
als to air. Using a light-colored plastic will
help prevent overheating, which can dry out
the clay materials. If the clay liner will not be
covered with a geosynthetic, another method
to prevent desiccation involves covering the
clay with a layer of protective cover soil
approximately one foot in thickness.
   Protection against freezing is another
important consideration, because freezing
may increase the hydraulic conductivity of a
liner. Avoid construction during freezing
weather. If freezing does occur and the dam-
age affects only a shallow depth, the liner
may be repaired by rerolling the surface. If
deeper freezing occurs, the repairs may be
more complicated. For a general guide to
frost depths, see Figure 1 of the chapter on
performing closure and post-closure care.

 B.     Geomembranes  or
        Flexible Membrane
    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


                                                            Protecting Ground Water—Designing and Installing Liners
biocides. A wide range of plastic resins are
used for geomembranes, including polyvinyl
chloride (PVC), high density polyethylene
(HDPE), linear low density polyethylene
(LLDPE), and chlorosulfonated polyethylene
(CSPE). Most manufacturers produce
geomembranes through extrusion or calen-
dering. In the extrusion process, a molten
polymer is stretched into a nonreinforced
sheet; extruded geomembranes are usually
made of HDPE and LLDPE. During the calen-
dering process, a heated polymeric com-
pound is passed through a series of rollers. In
this process, a geomembrane may be rein-
forced with a woven fabric or fibers.
Calendered geomembranes are made of PVC
and CSPE.
What are the thickness recom-
mendations for geomembrane
   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 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 consid-
ered 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,
examine several properties of the geomem-
brane material in addition to thickness,
including:  tensile behavior, tear resistance,
puncture resistance, susceptibility to environ-
mental stress cracks, ultraviolet resistance,
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 suf-
  ficient to satisfy the stresses anticipated
  during its service life. These stresses
  include the self-weight of the geomem-
  brane and any down drag caused by waste
  settlement on side slope liners.

  Puncture and Tear Resistance. Geomem-
  brane liners may be subject to tearing during
  installation due to high winds or handling.
  Puncture resistance is also important to con-
  sider since geomembranes are often placed
  above or below materials that may have
  jagged or angular edges. For example,
  geomembranes may be installed above a
  granular drainage system that includes gravel.

  Susceptibility to Environmental Stress
  Cracks. Environmental factors may 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


Protecting Ground Water—Designing and Installing Liners
                      the geomembrane liner has greater expo-
                      sure to the atmosphere and temperature
                      changes, such exposure may increase the
                      potential for environmental stress cracking.

                      Ultraviolet Resistance. Ultraviolet resis-
                      tance is another factor to consider in the
                      design of geomembrane liners, especially
                      in cases where the liner may be exposed to
                      ultraviolet  radiation for prolonged periods
                      of time. In such cases, which often occur
                      in surface impoundments, ultraviolet radi-
                      ation may cause degradation and cracking
                      in the geomembrane. Adding carbon black
                      or other additives during the manufactur-
                      ing process may increase a geomembrane's
                      ultraviolet  resistance.
                    Interactions With Waste
                       Since the main purpose of a geomembrane
                    is to provide a barrier and prevent contami-
                    nants from penetrating through the geomem-
                    brane, chemical resistance is a critical consid-
                    eration. Testing for chemical resistance may
                    be warranted depending on the type, vol-
                    umes, and characteristics of waste managed
                    at a particular unit. An established method
                    for testing the chemical resistance of
                    geomembranes, EPA Method 9090, can be
                    found in SW-846. ASTM has also adopted
                    standards for testing the chemical compatibil-
                    ity of various geosynthetics, including
                    geomembranes, with leachates from waste
                    management units. ASTM D-5747 provides a
                    standard for testing the chemical compatibili-
                    ty 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 differential settlement in foundation soil,
strain requirements at the anchor trench,
strain requirements over long, steep side
slopes, stresses resulting from compaction,
and seismic stresses. Often an anchor trench
designed to secure the geomembrane during
construction is prepared along the perimeter
of a unit cell. This action can help prevent
the geomembrane from slipping down the
interior side slopes. Trench designs should
include a depth of burial sufficient to hold
the specified length of liner. If forces larger
than the tensile strength of the liner are inad-
vertently developed, then the liner could tear.
For this reason, the geomembrane liner
should be allowed to slip or give in the
trench after construction to prevent such
tearing. To help reduce unnecessary stresses
in the liner design, avoid using horizontal
seams. For more information on design
stresses, consult U.S. EPA Geosynthetic
Guidance for Hazardous Waste Landfill Cells
and Surface Impoundments (EPA600-2-87-
Designing/or Adequate Friction
   Adequate friction between the geomem-
brane liner and the soil subgrade, as well as
between any geosynthetic components, is
necessary to prevent extehsive 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
configuration for the liner, (4) the stability of
soil cover on top of a liner, and (5) the stabil-
ity of other geosynthetic components,  such as
geotextiles or geonets, on top of a liner. An
evaluation of these issues may affect the
choice of geomembrane material, polymer
type, fabric reinforcement, thickness, and
texture necessary to achieve the design
                    7ASTM D-5747, Practice for Tests to Evaluate the Chemical Resistance of Geomembranes to Liquids.


                                                            Protecting Ground Water—Designing and Installing Liners
What issues should be consid-
ered  in  the construction of a
geomembrane liner?
  When preparing to construct a geomem-
brane liner, plan appropriate shipment and
handling procedures, perform testing prior to
construction, prepare the subgrade, consider
temperature effects, and account for wind
effects.  In addition, select a seaming process,
determine a material for and method  of back-
filling, and plan for testing during construction.
Shipment, Handling, and Site Storage

  Follow quality assurance and quality con-
trol procedures to ensure proper handling of
geomembranes. Different types of geomem-
brane liners require different types of packag-
ing for shipment and storage. Typically a
geomembrane manufacturer will provide spe-
cific instructions outlining the handling, stor-
age, and construction specifications  for a
product. In general, HDPE and LLDPE
geomembrane liners are packaged in a roll
form, while PVC and CSPE-R liners  (CSPE-R
refers to a CSPE geomembrane liner rein-
forced 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, ensure proper stor-
age. The rolls and panels should be packaged
so that fork lifts or other equipment can safe-
ly 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, may 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 protect  against ultravi-
olet exposure, and using banding straps with
appropriate cushioning. Once  the liners have
been transported to the site, the  rolls or pan-
els may be stored  until the subgrade or sub-
base (either natural soils or another geosyn-
thetic) is prepared.
Subgrade Preparation
   Before a geomembrane liner is installed,
prepare the subgrade or subbase. The sub-
grade material should meet specified grading,
moisture content, and density requirements.
In the case of a soil subgrade, ensure that
construction equipment used to place the
liner does not deform the underlying materi-
als. If the underlying materials are geosyn-
thetics, such as geonets or geotextiles, remove
all folds and wrinkles before  the liner is
placed. For further information on geomem-
brane placement, see Chapter 3 of EPA's
1993 technical guidance document Quality
Assurance and Quality Control for Waste
Containment Facilities (EPA600-R-93-182).
Testing Prior to Construction
   Before any construction begins, test both
the geomembrane materials from the manu-
facturer and the installation procedures.
Acceptance and conformance testing is used
to evaluate the performance of the manufac-
tured geomembranes. Constructing  test strips
may help evaluate how well the intended
construction process and quality control pro-
cedures will work.
   Acceptance and Conformance Testing.
Perform acceptance and conformance testing
on the geomembrane liner received from the
manufacturer to determine whether  the mate-
rials meet the specifications requested. While
the specific ASTM test methods vary depend-
ing on geomembrane type, recommended
acceptance and conformance testing for
geomembranes includes evaluations  of thick-
ness, tensile strength and elongation, and
puncture and tear resistance testing, as appro-
priate. For most geomembrane liner types, the


Protecting Ground Water—Designing and Installing Liners
                    recommended ASTM method for testing
                    thickness is ASTM D-5199.8 For tensile
                    strength and elongation, ASTM D-638 is rec-
                    ommended for the HDPE and LLDPE sheets,
                    while ASTM D-882 and ASTM D-751 are rec-
                    ommended for PVC and CSPE geomem-
                    branes, respectively.9 Puncture resistance test-
                    ing is typically  recommended for HDPE and
                    LLDPE geomembranes using Federal Test
                    Method (FTM) Standard 101C To evaluate
                    tear resistance-for HDPE, LLDPE, and PVC
                    geomembrane liners, the recommended test-
                    ing method is ASTM D-1004, Die C11 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.12

                      Test Strips. In preparation for liner place-
                    ment and field seaming, develop test strips
                    and trial seams as  part of the construction
                    process. Construction of such samples
                    should be performed in a manner that repro-
                    duces 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 may be altered
                    by extreme temperatures. High temperatures
                    may cause geomembrane liner surfaces to
                    stick together, a process commonly referred
                    to as blocking. On the other hand, low tem-
                    perature may cause the liner to crack when
                    unrolled or unfolded. Recommended maxi-
                    mum and minimum allowable sheet tempera-
                    tures for unrolling or unfolding geomem-
                                            brane liners are 50 °C (122 °F) and 0 °C (32
                                            °F), respectively. In addition to sticking and
                                            cracking, extreme temperatures may cause
                                            geomembranes to contract or expand.
                                            Polyethylene geomembranes expand when
                                            heated and contract when cooled. Other
                                            geomembranes may contract slightly when
                                            heated. Those responsible for placing the
                                            liner need to take temperature effects into
                                            account as they place, seam, and backfill in
                                            the field.
                                             Wind Effects
                                               Take measures to protect geomembrane
                                             liners from wind damage. Windy conditions
                                             may increase the potential for tearing as a
                                             result of uplift. If wind uplift is a potential
                                             problem, panels may 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, use: the seaming
                                             method recommended by the manufacturer.
                                             Thermal seaming uses heat to bond together
                                             the geomembrane panels.  Examples of ther-
                                             mal seaming processes include extrusion
                                             welding and thermal fusion (or melt bond-
                                             ing). Chemical seaming may involve the use
                                             of solvents, cement,  or an adhesive. Chemical
                                             seaming processes include chemical fusion
                                             and adhesive seaming. For more information
                                             on seaming methods, the EPA document,
*ASTM D-5199, Standard Test Method for Measuring Nominal Thickness of Geotextiles and Geomembranes.

9 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.                       :

M FTM Standard 101 C, Puncture Resistance and Elongation Test (1/8 Inch Radius Probe Method).
11 ASTM D-1004, Standard Test Method for Initial Tear Resistance of Plastic Film and Sheeting.

" ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.


                                                             Protecting Ground Water—Designing and Installing Liners
Technical Guidance Document: Inspection
Techniques for the Fabrication of Geomembrane
Field Seams (EPA530-SW-91-051), contains a
full chapter on each of the traditional seam-
ing methods and additional discussion of
emerging techniques, such as ultrasonic, elec-
trical conduction, and magnetic energy
source methods.
   Consistent quality in fabricating field
seams is paramount to liner performance.
Conditions that could affect seaming should
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.
   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 may 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 may increase  the ambient
temperature of the geomembrane,  making
installation more complicated. To avoid sur-
face moisture or high subsurface water con-
tent, 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
may affect the potential for tearing or punc-
turing the liner. To prevent wrinkling, soil
covers should be placed over the geomem-
brane 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.


Protecting Ground Water—Designing and Installing Liners
                    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
                    may 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
                    important  factor,  as it will effect the ability of
                    the liner to contract and expand. Although
                    the recommended methods for covering
                    geomembrane liners with soil may take more
                    time than backfilling with larger amounts of
                    soil, these  methods are designed to prevent
                    damage caused by covering the liner with too
                    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 geosynthetics that are often
                    used as protective covering include geotex-
                    tiles and geonets. Geogrids and drainage geo-
                    composites may be  used  for cover soil rein-
                    forcement  on slopes. Consult Appendix VIII
                    for additional information on geosynthetic
                    materials. For geosynthetic protective covers,
                    as with soil backfilling, to prevent tearing or
                    puncturing, construction vehicles should not
                    be permitted to move directly on the
                    geomembrane. Seaming-related equipment
                    may 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 test-
  ing includes shear testing and peel testing;
  for liner sheets, it involves tensile testing.
  While quality control procedures often
  require destructive testing prior to con-
  struction, in order to ensure that the
  installed seams and sheets meet perfor-
  mance standards, destructive testing
  should be performed during construction
  also. For increased quality assurance, peel
  and shear tests on samples from the
  installed geomembrane should be per-
  formed by an independent laboratory.
  Testing methods for shear testing, peel
  testing, and tensile testing vary for differ-
  ent geomembrane liner types.

  Determining the number of samples to
  take is a difficult step. Taking too few sam-
  ples results in a poor statistical representa-
  tion 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 which 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 230 m (250 to 750 ft), with a
  commonly specified value of 150 m (500
  ft). The type of welding, such as extrusion
  or fusion welding, used to connect the


                                                           Protecting Ground Water—Designing and Installing Liners
  seams and the type of geomembrane liner
  may also help determine the appropriate
  sampling interval. For example, extrusion
  seams on HDPE require grinding prior to
  welding and if extensive grinding occurs,
  the strength of the HDPE may decrease. In
  such cases, sampling at closer intervals,
  such as 90 to 120 m (300 to 400 ft), may
  provide a more accurate description of
  material properties. If the seam is a dual
  hot edge seam, both the inner and outer
  seams may 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, continue testing the area
surrounding the rejected sample to determine
the limits of the low quality  seam. Once the
area of low quality has been identified, then
corrective measures, such as seaming a cap
over the length of the seam or reseaming the
affected area, may be necessary.

  Nondestructive Testing. Unlike destructive
  tests, which examine samples taken from
  the geomembrane liner, nondestructive
  tests are designed to evaluate the integrity
  of larger portions of geomembrane seams
  without removing pieces of the geomem-
  brane 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. Select
  the test method most appropriate for the
  material and seaming method. If sections
  of a seam fail to meet the  acceptable crite-
  ria 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 should be used 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 and/or geomembranes held
together by needling, stitching, or chemical
adhesives. GCLs can be used to augment or
replace compacted clay liners or geomem-
branes, or they can be used in a composite
manner to augment the more traditional
compacted clay or geomembrane materials.
GCLs are typically 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 may require demonstration
that performance of the GCL design will be
comparable to that of compacted clay or
geomembrane liners.

What are  the mass  per  unit area
and hydraulic conductivity rec-
ommendations 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, design for a mini-
mum of 4 kg/m2 (0.8 lb/ft2) dry weight (oven
dried at 105 °C) of bentonite clay with a
hydrated hydraulic conductivity of no more
than  5 x lO'9 cm/sec (2 x 1Q-9 in/sec).  Follow
manufacturer specifications for proper GCL


Protecting Ground Water—Designing and Installing Liners
                    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, 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 need to be clearly defined in the
                    specifications used during both manufacture
                    and construction. Properties that need to  be
                    specified include: type of bonds, thickness,
                    moisture content, mass per unit area, shear
                    strength, and tensile strength. Each of these
                    properties is described below.
                      Type of bonds. Geosynthetic clay liners
                      are available with a variety of bonding
                      designs, which include a combination of
                      clay, adhesives, and geomembranes or geo-
                      textiles. 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  the clay layer.
                      Alternatively, another option is to use a
                      GCL where  geotextiles on each side of
                      adhesive or  nonadhesive bentonite clay are
                      connected by needle punching. A fourth
                      variation uses a clay mixed with  an adhe-
                      sive bound to a geomembrane on one
                      side; the geomembrane can be either the
                      lower or the upper surface. Figure 3 dis-
                      plays cross section sketches of the four
variations of GCL bonds. While these
options describe GCLs available at the
time of this guidance, emerging technolo-
gies 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; this may be referred
to as the  "dry" state. GCLs are delivered
dry to prevent premature hydration,  which
can cause unwanted variations in 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, bentoriite clay may be
placed between geotextiles and stitch
bonded or needle-punched to provide
additional stability. For example, a GCL
with geotextiles supported by stitch bond-
ing 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 slopes.


                                                            Protecting Ground Water—Designing and Installing Liners
                                      Figure 3.
                       Four variations of GCL Bonding Methods
 Upper Geocottilc
 Lower Geotextile
               (a) Adhesive Bound day to Upper and Lower Geotextiles
  Upper Geoexrile
                                                              in Row*
                                                             Lower Geomile

                  Stitch Bonded day Between Upper and Lower Geotextiles
              *       .                                ^-— — Lower GeoKxtila

                (c) Needle Punched day Through Upper and Lower Geotextiles
                    (d) Adhesive Bound Gay tiaaGeomembnne
.Lower or Upper
Source: U.S. EPA. 1993. Technical Guidance Document: Quality Assurance and Quality
Control For Waste Containment Facilities. EPA600-R-93-182.


Protecting Ground Water—Designing and Installing Liners
                    Interaction With Waste
                      During the selection process for a GCL
                    liner, evaluate the chemical compatibility 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, a quali-
                    fied professional should prepare construction
                    specifications for the GCL-In these specifica-
                    tions, procedures for shipping and storing
                    materials, as well as performing acceptance
                    testing on delivered materials, should be
                    identified. The specifications should also
                    address methods for subgrade preparation,
                    joining panels, repairing sections, and protec-
                    tive backfilling.
  To reduce the potential for accidental dam-
age or for GCLs to absorb moisture at the site,
try to arrange for "just-in-time-delivery" for
GCLs transported from the factory to the field.
Even with "just-in-time-delivery," it may be
necessary to store GCLs for short periods of
time at the site. Often the rolls can be deliv-
ered in trailers, which can then serve as tem-
porary storage. To help protect the GCLs prior
to deployment, use wooden pallets to keep the
rolls off the ground, placing heavy, waterproof
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 may damage the
liner during deployment.
                    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
                    hydration. 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, qualified professionals
                    should specify  the equipment needed at the
                    site to lift and deploy the rolls properly.
Acceptance and Confarmance Testing
   Perform acceptance arid conformance test-
ing either upon delivery of the GCL rolls or
at the manufacturer's 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 immediate-
ly after test samples are removed. Liner speci-
fications should prescribe sampling frequen-
cies based on either total area or on number
of rolls. Conformance testing may include the


                                                              Protecting Ground Water—Designing and Installing Liners
   Mass Per Unit Area Test The purpose of
   evaluating mass per unit area is to ensure
   an even distribution of bentonite through-
   out the GCL panel. Although mass per
   unit area varies from manufacturer to man-
   ufacturer, a typical minimum value for
   oven dry weight is 4 kg/m2 (0.8 lb/ft2).
   Mass per unit area should be tested using
   ASTM D-5993.13 This test measures the
   mass of bentonite per unit area of GCL.
   Sampling frequencies should be deter-
   mined using ASTM D-4354.14

   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.15

   Direct Shear Test. Shear strength of the
   GCLs can be evaluated using ASTM D-
   5321.16 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.17

   Other Tests. Testing of any geotextiles or
   geomembranes should be made on the
   original rolls of the geotextiles or geomem-
   branes and before they are fabricated into
   the GCL product.  Once these materials
   have been made part of the GCL product,
   their properties may 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 frequency of one
   test per 2,000 m2 (20,000 ft2).18
 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
 10'3 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, clearly specify minimum and maxi-
mum overlap distances. Typical overlap dis-
tances range from 150 to 300 mm (6 to 12
in.). For some GCLs, such as needle punched
13 ASTM D-5993, Standard Test Method for Measuring Mass per Unit Area of Geosynthetic Clay Liners.

14 ASTM D-4354, Standard Practice for Sampling of Geosynthetics for Testing.

15 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.

16 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or
 Geosynthetic and Geosynthetic Friction by the Direct Shear Method.

17 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).

18 ASTM D-413, Standard Test Methods for Rubber Property-Adhesion to Flexible Substrate.


Protecting Ground Water—Designing and Installing Liners
                   GCLs with nonwoven geotextiles, it may be
                   necessary to place bentonite on the area of
                   overlap. If this is necessary, prevent fugitive
                   bentonite particles from coming into contact
                   with the leachate collection system, as they
                   may cause physical clogging.
                   Repair of Sections Damaged During liner

                     During installation, GCLs may incur some
                   damage to either the clay component or to
                   any geotextiles or geomembranes. For dam-
                   age to geotextile or geomembrane compo-
                   nents, repairs may include patching, using
                   geotextile or geomembrane materials. If the
                   clay component is disturbed, a patch made
                   from the same GCL product should be used
                   to perform any repairs.
                   Protective Bocfe/illing
                     As soon as possible after completion of
                   quality assurance and quality control activi-
                   ties, cover GCLs with either a soil layer or a
                   geosynthetic layer to prevent hydration. The
                   soil layer may be a compacted clay liner or a
                   layer of coarse drainage material. The geosyn-
                   thetic layer  is typically  a geomembrane; how-
                   ever, depending on site-specific designs, it
                   can be a geotextile. As noted earlier, prema-
                   ture hydration before covering can lead to
                   uneven swelling, resulting in a GCL with var-
                   ied thickness. Therefore, a GCL should be
                   covered with its subsequent soil or geosyn-
                   thetic layer  before a rainfall or snowfall
                   occurs. Premature hydration is less of a con-
                   cern for GCLs, where the geosynthetic com-
                   ponents are needle punched or stitch bond-
                   ed, because these types of connections  can
                   better limit clay expansion.
III.  Composite

  A composite liner consists of both a
geomembrane liner and a compacted clay
liner (or a GCL). A composite liner provides
an effective hydraulic barrier by combining
the complementary properties of the two dif-
ferent liners into one system. The geomem-
brane provides a highly impermeable layer to
maximize leachate collection and removal.
The compacted clay liner serves as a backup
in the event of any leakage from the
geomembrane. This discussion refers only to
a compacted clay liner and geomembrane
composite liner. When a GCL is used as part
of a composite liner, it typically replaces the
compacted clay layer of the composite liner.
With a composite liner design, construct a
leachate collection and removal system above
the geomembrane. Information on design
and construction of leachate collection and
removal systems is provided in Section V

What are the thickness and
hydraulic conductivity  recommen-
dations 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 compacted
clay liners and geosynthetic clay liners, use
materials with maximum hydraulic conduc-
tivities of 1 x  10~7 cm/sec :(4 x 10~8 in/sec) and
5 x 10'9 cm/sec (2  x 10'9 in/sec), respectively.


                                                        Protecting Ground Water—Designing and Installing Liners
What issues should be considered
in the design  of a composite liner?
  As a starting point, follow the design con-
siderations discussed previously for single lin-
ers. In addition, to achieve the benefits of a
combined liner system, install the geomem-
brane to ensure good contact with the com-
pacted clay layer.  The uniformity of contact
between the geomembrane and the compact-
ed clay layer helps control the flow of
leachate. Porous material, such as drainage
sand or a geonet,  should not be 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 geomem-
brane imperfection.
  Consider the friction or shear strength
between a compacted clay layer and a
geomembrane. The friction or shear stress at
this surface is often low and may form a weak
plane on which sliding may occur. ASTM D-
5321 provides a test method for determining
the friction coefficient of soil and geomem-
branes.19 When using bentonite-amended soils,
account for how the percentage of bentonite
added and the degree of saturation affect inter-
face friction. To guarantee stable slopes, it is
important to control both the bentonite and
moisture contents. Consider using a textured
geomembrane to 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, smooth-roll the sur-
face of the compacted clay layer using a
smooth, steel-drummed roller and remove
 any stones. In addition, 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. To avoid
 damaging the clay layer, unroll geomem-
 branes by lifting the rolls onto jacks at a cell
 side and pulling down on the geomembrane
 manually. Also, the entire roll with its core
 may be unrolled onto the cell (with auxiliary
 support using ropes on embankments).

   To minimize desiccation of the compacted
 clay layer, place the geomembrane over the
 clay layer as soon as possible. Additional
 cover materials should also be placed over
 the geomembrane. Exposed geomembranes
 absorb heat, and high temperatures 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 withdrawal of water can
 lead to desiccation cracking and potential
 interface stability concerns.
IV.  Double Liners
       (Primary  and
       Secondary Lined
  In a double-lined waste management unit,
there are two distinct liners—one primary (top)
liner and one secondary (bottom) liner. Each
liner may consist of compacted clay, a geomem-
brane, or a composite (consisting of a geomem-
brane and a compacted clay layer or GCL).
Above the primary liner, construct a leachate
collection and removal system to collect and
19 ASTM D-5321, Standard Test Method for Determining the Coefficient of Soil and Geosynthetic or
 Geosynthetic and Geosynthetic Friction by the Direct Shear Method.


Protecting Ground Water—Designing and Installing Liners
                   convey liquids out of the waste management
                   unit and to control the depth of liquids above
                   the primary liner. In addition, 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 liq-
                   uid or leachate that has escaped the primary
                   liner. See Section V below for information on
                   the design of leachate collection and removal
                   systems and leak detection, collection, and
                   removal systems.

                   What are the thickness and
                   hydraulic conductivity recom-
                   mendations for  double  liners?
                     Each component of the double liner should
                   follow the recommendations for geomem-
                   branes, 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, com-
                   pacted clay liners should be at least 2 feet
                   thick and are typically 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 10'8
                   in./sec) and 5 x 10'9 cm/sec (2 x 10'9 in/sec),

                   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, consult the sections on compos-
                   ite and single liners first. In addition, consult
                   the sections on leachate collection and
                   removal systems and leak detection systems.
V.    Leachate

       Collection and

       Leak Detection

  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. Consult with
the state agency too determine if such sys-
tems are required. The primary function of a
leachate collection and removal system 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 sys-
tem is to detect leachate that has escaped the
primary liner. A leak detection system refers
to drainage material located below the prima-
ry liner and above a secondary liner (if there
is one); it acts as a secondary leachate collec-
tion and removal system.  After the leachate
has been removed and collected, a leachate
treatment system may be incorporated  to
process the leachate and remove harmful
  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, will not have leachate collec-
tion and removal systems unless they will be
closed in-place  as landfills; they may have
leak detection systems to; detect liquid  wastes
that have escaped the primary liner. No
leachate collection or leak detection systems
are used with land application.


                                                         Protecting Ground Water—Designing and Installing Liners
                                     Figure 4.
                          Typical Leachate Collection System
                                                Final grade
                                                               Manhole casing
                                   Sweep bend and cap
                                                                   Solid pipe
      rirrirrtLrrrX^^"—as^ir rrr.r^<---Sweep bend

                                         . Perforated pipe
                                    •Pipe backfill
Source: U.S. EPA. 1995. Decision Maker's Guide to Solid Waste Management, Volume II.
A.    Leachate Collection
  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.
What are the recommendations
for  leachate collection and
removal systems?
   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 is used. If a geosynthetic materi-
al is used, the leachate head should not
exceed the thickness of the geosynthetic
material (this mean the head cannot exceed
0.03 inches). 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.


Protecting Ground Water—Designing and Installing Liners
                       Design a leachate collection and removal
                    system capable of controlling the estimated
                    volume of leachate. To determine potential
                    leachate generation, use water balance equa-
                    tions or models. The most commonly used
                    method to estimate leachate generation is the
                    EPA's Hydrogeologic Evaluation of Landfill
                    Performance (HELP) model.20 This model uses
                    weather, soil, and waste management unit
                    design data to determine leachate generation

                    What  issues should be  consid-
                    ered in the design of a  leachate
                    collection  and removal  system?
                       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 design,  consider the
                    stability of the base, the transmissivity of the
                    drainage layers, and the strength of the col-
                    lection pipes. Also consider methods to mini-
                    mize physical, biological, and chemical clog-
                    ging 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 materials.
                                              For soil drainage materials, a maximum of 12
                                              inches of materials with a hydraulic conductiv-
                                              ity of at least 1 x 10'2 cm/sec (4 x 10° in./sec) is
                                              recommended. For this reason, sand and grav-
                                              el are the most common soil materials used. If
                                              the drainage layer is going to incorporate sand
                                              or gravel, it should be demonstrated that the
                                              layer will have sufficient 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 may be  used in addition to, or in
                                              place of, soil materials.  Geonets promote
                                              rapid transmission of liquids and should
                                              always be used in conjunction with a filter
                                              layer or geotextile to prevent clogging.
                                              Geonets consist of integrally connected paral-
                                              lel 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 depicts a
                                              typical geonet material configuration.
                                                 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  can be evaluat-
                                              ed by ASTM D-4716.21 Several  additional mea-
                                              sures for determining the transmissivity of
                                              geonets are discussed in the EPA document
                                              Solid Waste Disposal Facility Criteria: Technical
                                              Manual (EPA530-R-93-017).
20 Available from the U.S. Army Corps of Engineers Web site <iittp://www.wes.aimy.iniVel/elmodels/
21 ASTM D-4716, Standard Test Method for Constant Head Hydraulic Transmissivity (In-Plane Flow) of
Geotextiles and Geotextile Related Products.


                                                               Protecting Ground Water—Designing and Installing Liners
                              Figure 5.
                    Typical Geonet Configuration
Perforated Leadiate Collection Pipes
   Whenever the leachate collection system is
a natural soil, a perforated piping system
should be located within it to rapidly transmit
the leachate to a sump and removal system.
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 siz-
ing, and pipe structural strength. After estimat-
ing the amount of leachate using the HELP
model or a similar water balance model, it is
possible to calculate the appropriate pipe
diameter and spacing. For the leachate collec-
tion system design, 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 modern waste man-
agement 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 management
units, but they are not as chemically resistant
as HDPE pipes.
                       Protective Filter Layer
                         To protect the
                       drainage layer and per-
                       forated leachate collec-
                     tion piping from clog-
                     ging, place a filter layer
                     over the high-permeabil-
                     ity 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 filtration. Select
sand that allows adequate flow of liquids, pre-
vents migration of overlying solids or soils into
the drainage layer, and minimizes clogging
during the service life. In designing the sand
filter, consider particle size and hydraulic con-
ductivity. The advantages of using sand materi-
als 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 particles.
The number of openings in the geotextile
should be large enough that, even if some of
the openings clog, the remaining openings will
be sufficient to pass the design flow rate. In
addition to pore size,  geotextile filter specifica-
tions should include durability requirements.
The advantages of geotextile materials include
vertical space savings  and easy placement.
Chapter 5 of EPA's 1993 technical guidance
document Quality Assurance and Quality
Control for Waste Containment Facilities
(EPA600-R-93-182) offers guidance on protec-
tion of drainage layers.


Protecting Ground Water—Designing and Installing Liners
                    Lcadiate Removed 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. Modem 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. Reinforced concrete
                    pipe and concrete flooring may be used in
                    place of the polyethylene structure but are
                    considerably heavier.
                       To remove leachate that has collected in the
                    sump, 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 collec-
                    tion to prevent the  pump from running dry.
                    Consider installing a level control, backup
                    pump, and warning system to ensure proper
                    sump operation. 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 malfunction.
                       Standpipes, vertical pipes extending
                    through the waste and cover system, offer one
                    method of removing leachate from a sump
                    without puncturing the liner. Alternatively,
                     remove leachate from a sump using pipes that
                     are designed to penetrate the liner. When
                     installing pipe penetrations through the liner,
                     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 chemi-
                     cal clogging. Physical clogging may occur
through the migration of finer-grained materi-
als into coarser-grained materials, thus reduc-
ing the hydraulic conductivity of the coarser-
grained material. Biological clogging may
occur through bacterial growth in the system
due to the organic and nutrient materials in
leachate. Chemical clogging may be caused by
chemical precipitates, such as calcium carbon-
ates, causing blockage or cementation of gran-
ular drainage material.
   Proper selection of drainage and filter
materials is essential to minimize clogging in
the high-permeability drainage layer. Soil and
geotextile filters may be used to minimize
physical clogging of both  granular drainage
material and  leachate collection pipes. When
placed above granular drainage material,
these filters may also double as an operations
layer to prevent 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
   The leachate collection  pipes are also sus-
ceptible to  similar clogging. To prevent this,
incorporate measures into the design to allow
for routine pipe cleaning, using either
mechanical or hydraulic methods. The clean-
ing components can include pipes with a 15
cm (6-in.) minimum diameter to facilitate
cleaning, access located at major pipe intersec-
tions or bends to allow for inspections and
cleaning, and valves, ports, or other appurte-
nances to introduce biocides and/or cleaning
solutions. Consider incorporating an antimi-
crobial additive into the plastic composition to
delay or reduce biological growth. Also,
ensure that the design does not include wrap-
ping perforated leachate collection pipes
directly with geotextile filters. If the geotextile
becomes clogged, it can block flow into the


                                                            Protecting Ground Water—Designing and Installing Liners
 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 system and
 identifies any leakage from the primary liner
 system. It also serves to collect and remove
 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 both the bottom and
 side walls of a waste management unit. The
 LDS should be designed to collect leakage
 through the primary layer and transport it to a
 sump within 24 hours.
   The LDS should allow for monitoring and
 collection of leachate escaping the primary
 liner system. Monitor the LDS on a regular
 basis. If the volume of  leachate detected by  the
 LDS appears to be increasing or is significant,
 consider a closer examination to determine
 possible remediation 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 may need closer monitoring or

 C.    Leachate  Treatment
   Once the leachate has been removed from
 the unit and collected,  take measures to char-
 acterize the leachate in  order to ensure proper
 disposal. There are several methods of disposal
 for leachate, and the  treatment strategy will
vary according to the disposal method chosen.
 Leachate disposal options include discharging
 to or pumping and hauling to a publicly
 owned treatment works or to an on-site treat-
 ment system; treating and discharging to the
 environment; land application; and natural or
 mechanical evaporation.

   When discharging to or pumping and haul-
 ing leachate to a publicly owned treatment
 works, a typical treatment strategy includes
 pre-treatment. Pre-treatment could involve
 equalization, aeration, sedimentation, Phone:
 adjustment, or metals removal.22 If the plan for
 leachate disposal does not involve a remote
 treatment facility, pre-treatment alone is not

   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
 micro-organisms to biodegrade organic conta-
 minants in leachate."23 Among physical/chemi-
 cal treatment techniques, the carbon absorption
 process and reverse osmosis are the two most
 common methods. Carbon absorption uses car-
 bon to remove dissolved organics from leachate
 and is very expensive. Reverse osmosis involves
 feeding leachate into  a tubular chamber whose
 wall acts as a synthetic membrane, allowing
 water molecules to pass through but not pollu-
 tant molecules, thereby separating clean water
 from waste constituents.
What are  the  recommendations
for leachate treatment systems?
   Review all applicable federal and state regu-
lations 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 treat-
ment system. For some facilities, onsite storage
and treatment may not be an option due to
u Arts, Tom. "Alternative Approaches For Leachate Treatment." World Wastes.


Protecting Ground Water—Designing and Installing Liners
                   space constraints. For other facilities, having a
                   nearby, publicly owned treatment works may
                   make pre-treatment and discharge to the treat-
                   ment works an attractive alternative.
                   VI,   Construction


                           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
                   discussed only briefly here since they are pri-
                   marily the responsibility of a manufacturer.
                   Nonetheless, select a manufacturer who
                   incorporates appropriate quality assurance
                   and quality control (QA and QC) mecha-
                   nisms as part of the manufacturing process.
                   The remainder of this section provides a gen-
                   eral description of the components of a con-
                   struction 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 distinction between
                    them should be kept in mind when prepar-
                    ing plans. CQA is third party verification of
                    quality, while CQC consists of in-process
                    measures taken by the contractor or installer
                    to maintain quality. Establish clear protocols
                    for identifying and addressing issues of con-
                    cern throughout every stage of construction.
What is manufacturing quality
  The desired characteristics of liner materials
should be specified in the 'unit's contract with
the manufacturer. The manufacturer is respon-
sible for certifying that materials delivered
conform to those specifications. MQC imple-
mented to ensure such conformance 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  per-
sonnel or engineers to visit the manufacturing
facility, and provide liner samples for testing.
The manufacturer should have a dedicated
individual in charge of MQC who would work
with unit personnel in these areas.
  MQC, MQA, CQC, and CQA
  Manufacturing quality control (MQC) is
  measures taken by the manufacturer to
  ensure compliance with the material and
  workmanship specifications of the facility
  Manufacturer quality assurance (MQA) is
  measures taken by facility personnel, or
  by an impartial party brought in expressly
  for the purpose, to determine if the man-
  ufacturer is in compliance with the speci-
  fications of the facility manager.
  Construction quality control (CQQ is
  measures taken by the installer or con-
  tractor to ensure compliance  with the
  installation specifications of the facility
  Construction quality assurance (CQA) is
  measures-taken by facility personnel, or by
  an impartial party brought in expressly for
  the purpose, to determine if the installer
  or contractor is in compliance with the
  installation specifications of the facility


                                                             Protecting Ground Water—Designing and Installing Liners
 What  is construction quality
   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 final product
 meets project specifications. CQA testing,
 often referred to  as acceptance inspection, pro-
 vides a measure of the final product quality
 and its conformance with project plans and
 specifications. Performing acceptance inspec-
 tions routinely, as portions of the project
 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 the facility's in-
 house CQA personnel may be registered pro-
 fessional engineers, a perception of misrepre-
 sentation may 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 facili-
 ty manager that may impact his or her impar-
 tiality or objectivity. If such activities or rela-
 tionships exist, the CQA officer should
 describe actions that have been or can be
 taken to avoid, mitigate, or neutralize the  pos-
 sibility 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
   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 specifications
 and plans. Since CQC is a production tool
 employed by the manufacturer of materials
 and by the contractor installing the materials
 at the site, this guidance 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 will require indepen-
 dent testing of those same seams by a third-
 party inspector.

 How can  implementation of
 CQA and  CQC plans be
  When preparing to design and construct a
waste management unit, regardless of liner
 type, develop CQA and CQC plans cus-
tomized to the project. To help the project run
smoothly, the CQA plan should be easy to fol-
low.  Organize the CQA plan to reflect the
sequence of construction and write it in lan-
guage that will be familiar to an average field
technician. For a more detailed discussion of
specific CQA and CQC activities recommend-
ed for each type of waste management unit,
consult the EPA document Technical Guidance
Document: Quality Assurance and Quality
Control for Waste Management Containment
Facilities (EPA600-R-93-182). This document
provides information needed to develop


Protecting Ground Water—Designing and Installing Liners
                    comprehensive QA plans and to carry out QC
                    procedures at waste management 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. Define responsibility and authority in
                    written QA and QC plans and ensure that
                    each party involved understands its role. Pre-
                    construction meetings are one way to help
                    clarify roles and responsibilities. During con-
                    struction, meetings may continue to be useful
                    to help resolve misunderstandings and to
                    identify solutions to unanticipated problems
                    that may develop. Some examples of typical
                    meetings during the course of any construc-
                    tion project include pre-bid meetings, resolu-
                    tion meetings, pre-construction meetings, and
                    progress meetings.

                    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. In the
                     CQA and CQC plans, specify procedures for
                     quality assurance and quality control 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 prop-
erties such as moisture content, soil density,
Atterberg limits, grain size,, and laboratory
hydraulic conductivity. Additional testing of
soil moisture content, density, lift thickness,
and hydraulic conductivity ensures 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 indepen-
dent 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 may include  com-
municating with the contractor; interpreting
and clarifying project drawings and specifica-
tions with the designer, facility manager, and
contractor; recommending acceptance or
rejection by the facility manager of work com-
pleted by the construction contractor; and
submitting blind samples, such as duplicates
and blanks,  for analysis by the contractor's
testing staff or independent laboratories.
   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 proce-
dures can produce a liner that performs
according to the construction drawings and
   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


                                                             Protecting Ground Water—Designing and Installing Liners
 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
 •'•equirements 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 liners,
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 gener-
ally 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 liners
in storage, and handling of the liner as the
panels are positioned  in the cell. Geomem-
brane CQA staff should also observe seam
preparation, seam overlap, and materials
underlying the liner.

How can implementation of QA
and QC be ensured for a
geomembrane  liner?
   Prior to installation, 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. In addi-
tion, 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 may be responsible for observations of
 destructive testing conducted on scrap test
 welds prior to seaming. Geomembrane CQA
 staff may 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/or handling and placement and observa-
 tions 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. Allow for testing  frequency to change,
 based on the performance  of the geomem-
 brane installer. If test results indicate poor
 workmanship, increase testing. If test results
 indicate high quality  installation work, con-
 sider reducing testing frequencies. When
 varying testing frequency, establish well-
 defined procedures for modifying testing fre-
 quency. In evaluating testing methods, under-
 stand the differences  among testing methods
 and  request those methods appropriate for
 the material and seaming method used. Use
 nondestructive testing methods when possi-
 ble to help reduce the number of holes cut
 into the geomembrane.

   Geomembrane CQA staff also need to 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, loca-
 tions of seams constructed,  and any problems
 encountered. In some cases, they may need to
 prepare drawings of the liner installation.
 Record drawing preparation is frequently
assigned to the contractor, to a representative
of the facility manager, or to the engineer.
Request complete reports from any CQA staff


Protecting Ground Water—Designing and Installing Liners
                   and the installers. To ensure complete CQA
                   documentation, 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 control
                   procedures. The CQA recommendation for
                   GCLs can serve as a starting point. Check with
                   the GCL manufacturer and installer for more
                   specific information.

                    How can implementation of  QA
                    and QC be ensured for a
                    geosynthetic clay liner?
                      Develop a detailed CQA plan, including
                    product specifications; shipping, handling,
                    and storage procedures; seaming methods;
                    and placement of overlying material. Work
                    with the  manufacturer to verify that the prod-
                    uct meets specifications. Upon receipt of the
                    GCL product, verify that it has arrived in good
                       During construction, CQA staff will want to
                    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. Prohibit direct vehicle
                    traffic, with the exception of small, 4-wheel,
                    all terrain vehicles. Even with the small all-ter-
                    rain vehicles, drivers should take extreme care
                    to avoid movements, such as sudden starts,
                    stops, and turns, which may damage the GCL.
                       As part of the CQA documentation, main-
tain records of weather conditions, subgrade
conditions, and GCL panel locations. Also
document any repairs that were necessary or
other problems identified and addressed.

D.    Leachate  Collection
       System  Quality
       Assurance and Quality
   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 of 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, electrical,
 and monitoring equipment; concrete forms
 and reinforcements; and prefabricated struc-
 tures such as sumps and manholes. The
 leachate collection system foundation, either a
 geomembrane or compacted clay liner, should
 also be inspected, upon its completion, to
 ensure that it has proper grading and is 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 geotextiles,
 sumps, and mechanical and electrical equip-
 ment. For pipes, observations may include
 descriptions of pipe bedding material, quality


                                                              Protecting Ground Water—Designing and Installing Liners
and thickness, as well as the total area covered
by the bedding material. Observations of pipe
installations should focus on the location, con-
figuration, and grading of the pipes, as well as
the quality of connections at joints.
   For granular filter layers, CQA activities
may include observing and documenting
material thickness and quality during place-
ment. For granular drainage layers, CQA may
focus on the protection of underlying liners,
material thickness, proper overlap with filter
fabrics and geonets (if applicable), and docu-
mentation of any weather conditions that may
affect the overall performance of the drainage
layer. For geonets and other geosynthetics,
CQA observations should focus on the area of
coverage and layout pattern,  as well  as the
overlap between panels. For geonets, CQA
staff may want to make sure that the materials
do not become clogged by granular material
that may be carried over, as a result of either
wind or run-off during construction.
   Upon completion of construction, each
component should be inspected to identify
any damage that may have occurred during its
installation or during construction of another
component. For example, a leachate collection
pipe may be crushed during placement of a
granular drainage layer. Any damage that does
occur should be repaired, and the repairs
should be documented in the CQA records.


Protecting Ground Water—Designing and Installing Liners


Action  Items for Lined  Units (Landfills,  Waste  Piles,  —

                  and  Surface Impoundments)

        Review the recommended location considerations and operating practices for the unit.

        Select appropriate liner type—single, composite, or double liner—or in-situ soils, based on
        risk characterization.

        Evaluate liner material properties and select appropriate clay, geosynthetic, or combination
        of materials; consider interactions of liner and soil material with waste.

        Develop a construction quality assurance (CQA) plan defining staff roles-and responsibili-
        ties and specifying test methods, storage procedures, and construction protocols.

        Ensure a stable in-situ soil foundation, for nonengineered liners.

        Prepare and inspect subgrade, for engineered liners.

        Work with manufacturer to ensure protective shipping, handling and storage of all materials.

        Construct a test pad for compacted clay liners.

        Test compacted clay liner material before and during construction.

        Preprocess clay material to ensure proper water content, remove oversized particles,
        and add soil amendments, as applicable.

        Use proper lift thickness and number of equipment passes to achieve adequate compaction.

         Protect clay material from drying and cracking.

         Develop test strips and trial seams to evaluate geomembrane seaming method.

         Verify integrity of factory and field seams for geomembrane materials before and during

         Backfill with soil or geosynthetics to protect geomembranes and geosynthetic clay liners
         during construction.

         Place backfill materials carefully to avoid damaging the underlying materials.

         Install geosynthetic clay liner with proper overlap.

         Patch any damage that occurs during geomembrane or geosynthetic clay liner installation.

         Design leachate collection and removal system to allow adequate flow and to minimize
         clogging; include leachate treatment and leak detection systems, as appropriate.

         Document all CQA activities, including meetings, inspections, and repairs.






                                                             Protecting Ground Water—Designing and Installing Liners
 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-lbf/ft3 (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

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.


Protecting Ground Water—Designing and Instating 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 nonhaz-
            ardous 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.

            Daniel, D.E., and R.M. Koerner. 1991. Landfill liners from top to bottom. Civil Engineering.

            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. EPA600-R-93-182.

            Daniel, D.E., and R.M. Koerner. 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.

            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.


                                                        Protecting Ground Water—Designing and Installing Liners
                               Resources  (cont.)
Geosynthetic Research Institute. 1993. GRI-GCL1, Swell measurement of the clay component of

Geosynthetic Research Institute. 1993. GRI-GCL2, Permeability of geosynthetic clay liners (GCLs).

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 E 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 prepar-
ing 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 pro-
cessing 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, chap-
ter 647. Sludge and land application of wastewater.


Protecting Ground Water—Designing and Installing Liners
                                            Resources (cont.)
           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.

           Spellman, E 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.

           University of Nebraska Cooperative Extension Institute of Agriculture and Natural Resources.  1991.
           Guidelines for soil sampling.  G91-1000-A. February.

           U.S. EPA. 1996. Issue paper on geosynthetic clay liners (GCLs).

           U.S. EPA. 1996. Report of 1995 Workshop on Geosynthetic Clay Liners. EPA600-R-96-149. June.

           U.S. EPA.  1995.  A guide to the biosolids risk assessments for the EPA Part 503 Rule.  EPA832-B-93-
           005. September.

           U.S. EPA. 1995. Decision maker's guide to solid waste management. Volume II. EPA530-R-95-023.

            U.S. EPA.  1995.  Laboratory methods for soil and foliar analysis in long-term environmental monitoring
            programs. EPA600-R-95-077.

            U.S. EPA.  1995.  Process design manual: Land application of sewage sludge and domestic septage.
            EPA625-R-95-001. September.

            U.S. EPA.  1995. Process design manual: Surface disposal of sewage sludge and domestic septage.
            EPA625-R-95-002. September.

            U.S. EPA. 1994. A plain English guide to the EPA Part 503 biosolids rule. EPA832-R-93-003.

            U.S. EPA. 1994.  Biosolids recycling: Beneficial technology for a better environment. EPA832-R-94-
            009. June.


              Part IV
      Protecting Ground Water

        Chapter 7: Section C
Designing A Land Application Program


Risk Assessment 7C~2
II.  Determining a Suitable Waste Application Rate for Land Application     7C-4
    A. Waste Parameters 7C'4
    B. Total Solids Content 7C'4
    C.pH    -   7C-6
    D. Biodegradable Organic Matter •   7C'6
    E. Nutrients    7C~7
    E Metals    7C"8
    G. Carbon to Nitrogen Ratio -   7C'8
    H. Soluble Salts    7C-9
    I. Calcium Carbonate Equivalent :   7C-11
    J. Pathogens    >   7C-11

 HI. Soil Properties    7C-12

 IV Plant and Microbial Effects ,   :   7C-1.4
    A. Greenhouse and Field Studies 7C-14
    B. Effects of Plants and Microbes on Waste Assimilation 7C-16
    C. Effects of Waste on Plant and Microbe Growth 7C-17
    D. Grazing and Harvesting Restrictions  7C-17

 V.  Climate    -   7C-18

 VI. Agronomic Rate T   7C-18

 VII. Monitoring    •   7C'19

 Action Items for Designing a Land Application Program  7C-21

                                                                                             7(~ T)
 Resources  ;•  i^-^

   Table  1:  Summary of Important Waste Parameters •   7C-5
   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


                             Contents (cont.)
 Figure 1: A Framework for Evaluating Land Application.



                                                     Protecting Ground Water—Designing A Land Application Program
        Designing  A  Land Application  Program

        Follow the evaluation framework recommended in this section
        when applying waste directly to the land for combination of soil
        amendment,  treatment, and disposal.  Account for the designat-
        ed ground-water constituents identified in the assessing risk
        section, as well as other waste parameters and factors such as
        soil properties and plant and microbial interactions.
          Land application offers some dis-
          tinct benefits. At the same time,
          because land application does not
          rely on liners to contain waste,
          there are some associated risks.
With proper planning and design, a land
application program can meet waste manage-
ment and land preservation goals and avoid
negative impacts such as anaerobic conditions,
noxious odors, long-term damage to soil, and
releases to ground water, surface water, or the
air. This section recommends an evaluation
framework to account for a variety of waste
parameters in addition to the constituents out-
lined in the assessing risk section1, and other
factors such as soil properties and plant and
microbial nutrient use2. A successful land
application program takes the interaction
among all these factors into account.
   If agricultural benefit is the primary pur-
pose of land application — to attenuate waste
and maximize plant growth while minimizing
environmental and health risks — the consid-
erations are numerous. If this involves short-
term application on a field, for example a year
or two under a contractual relationship with a
farmer, the evaluation may be completed
more quickly, but it is still important to  take
these factors into account. If the primary pur-
pose is waste treatment or disposal, the goal
of maximizing plant growth is probably less
important. However, ensure that the waste
application will not result in environmental
releases and have detrimental effects on  future
uses and revegetation of the site.
   Examples of land application benefits
include the following:
•   Biodegradation of Waste. If a waste stream
    contains sufficient organic material, plants
    and microorganisms can significantly
    biodegrade the waste, assimilating its
    organic components into the soil.  After
    allowing sufficient time for assimilation of
    the waste, more waste may be applied to a
    given site without significantly increasing
    the total  volume of waste at the site. This
'The constituents incorporated in the EPAIWEM to assess risk, such as heavy metals and synthetic organ-
ic chemicals, typically have little or no agricultural value and can threaten human health and the environ-
ment even in small quantities. The term "waste parameters" refers to waste constituents, such as nitro-
gen, biodegradable organic matter content, and pH, that have considerable agricultural significance and
that typically threaten human health and the environment only in larger quantities or at extreme levels.

HO 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 concerning pathogens, may be helpful in evaluating land applica-
tion for industrial wastes.  For mixtures of sewage sludge and industrial waste, the ground-water and air
risk assessments and the evaluation framework laid out in this guidance can help address constituents
that are not covered under the Part 503 regulations.


Protecting Ground Water—Designing A Land Application Program
                        is in contrast to landfills and waste piles,
                        in which waste accumulates continually
                        and does not biodegrade quickly enough
                        to reduce its volume significantly.
                    •   Inclusion of Liquids. Land application
                        units can accept bulk, non-containerized
                        liquid waste. The water content of liquid
                        wastes may make them desirable at land  .
                        application sites in arid climates. When
                        managing liquid waste, land application
                        may reduce the need for expensive
                        dewatering processes.
                    •   Improvement of SoiL Applied waste can
                        improve soil quality if the waste contains
                        appropriate levels of biodegradable organic
                        matter and nutrients. Nutrients can
                        improve the chemical composition of the
                        soils to better support vegetation, while
                        biodegradable organic matter can improve
                        soil physical properties to increase water
                        retention capacity. These chemical and
                        physical soil improvement aspects of land
                        application have led to its use in condi-
                        tioning soil for agricultural use.
                       Figure  1 outlines a framework for evaluat-
                    ing land application that incorporates both the
                    ground-water risk assessment recommended
                    in this chapter, as well as the other waste
                    parameters and factors important to land
                    application. Be sure to  address the waste para-
                    meters and other characteristics discussed in
                    this evaluation framework when characterizing
                    wastes for land application.
                     I.     Risk Assessment
                       If waste leachate contains any of the 191
                     constituents covered in the Tier I and II
                     ground-water models, follow the evaluation
                     recommended in subsections II through IV.
                     If the waste leachate does contain some of
                     these constituents, there are some initial steps
                     to follow:
                                                 1) Consider whether any of these con-
                                                 stituents are already addressed in any per-
                                                 mit, memorandum of .understanding, or
                                                 other agreement with a federal, state, or
                                                 other regulatory agency concerning land
                                                 application. The guidance is not meant to
                                                 supersede conditions established in these
                                                 regulatory mechanisms.3

                                                 Some wastes may 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 pre-
                                                 sent a greater environmental and health risk
                                                 than would use of the manufactured or raw
                                                 material it replaces. Equivalence designations
                                                 are included in the category of "other agree-
                                                 ments" above. If there are no designated
                                                 ground-water constituents other than those
                                                 on which the designation is based, follow the
                                                 guidelines offered in subsections II through
                                                 IV to determine an application rate. If there
                                                 are ground-water constituents other than
                                                 those on which the designation is based, pro-
                                                 ceed with a risk analysis, such as that
                                                 described in the section on assessing risk, for
                                                 those constituents.

                                                 2) Evaluate ground-water and air risks using
                                                 the modeling tools in this guidance or other
                                                 site-specific models. The ground-water
                                                 model recommends whether a waste is
                                                 appropriate for land application. In some
                                                 cases, pollution prevention or treatment may
                                                 lower constituents levels so that a waste can
                                                 be land applied. In other cases, land applica-
                                                 tion may not be feasible. In this event, pur-
                                                 sue other waste management options.

                                                 3) Consider direct exposure and ecosystem
                                                 pathways. They are more important in land
                                                 application, since only in land application is
                                                 waste placed in and attenuated by the natural
                                                 environment rather than contained by an
3EPA 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


                                       Protecting Ground Water—Designing A Land Application Program
          Figure 1. A Framework for Evaluating Land Application
                 Perform waste characterization
                      • Ground-water constituents
                       • Other waste parameters
   Evaluate waste
    Measure soil
 Study interaction of
 plants and microbes
     with waste
 Consider ecosystem
impacts and bioaccu-
  mulation of waste
 Account for climate
Determine theoretical
agronomic application
  Determine which
  constituents are
 covered by permits
   MOUs, or other
  For constituents
     covered by
 agreements, follow
terms of agreements

For constituents not
     covered by
 agreements, follow
  risk assessment
               Evaluate appropriate application rate and
                      constituent concentrations
                    Consider pollution prevention,
                       recycling, or treatment
                   Reassess periodically and after
                          process changes


Protecting Ground Water—Designing A Land Application Program
                     engineered structure. Although a qualitative
                     tool to evaluate these pathways is not pro-
                     vided, take them into consideration when
                     evaluating risks from a land application
                     unit. During die unit's active life, direct
                     human exposure to waste or waste-amended
                     soil is primarily a risk to personnel involved
                     in die operation. Follow OSHA standards
                     and ensure that personnel use proper pro-
                     tective clothing and equipment when work-
                     ing onsite. Limit direct exposure to others
                     through steps such as access control and
                     vehicle washing to prevent tracking waste
                     and waste amended soil off-site. Access con-
                     trol will limit exposure of some animals.  If
                     crops will be used for animal fodder or graz-
                     ing, test harvested fodder for die designated
                     ground-water constituents before use and
                     restrict grazing times. After a site is closed,
                     there may be long-term access risks to
                     future land uses and the general public. To
                     minimize these risks long-term access con-
                     trols or deed restrictions may be appropri-
                     ate. Consult the chapter on performing clo-
                     sure and  post-closure care for further infor-

                     Direct exposure of native animals is often
                     impossible to control and may be an entry
                     point for the ground-water constituents
                     into the ecosystem. Worms, for example,
                     may be present in the soil and take in
                     these constituents.  Birds or other animals
                     could then consume the worms, and in
                      doing so, not only bioaccumulate, but  also
                      transport them off-site. Furthermore, ani-
                      mals may ingest plants grown on waste-
                      amended soil. Consider pathways such as
                      diese in  evaluating risk.
II.    Determining  a

       Suitable  Waste
       Application  Rate

       for  Land
  The factors on the left side of Figure 1
provide the basics for determining a prelimi-
nary waste application rate. These factors are
discussed below.

A.     Waste Parameters
  For land application, in addition to the
designated ground-water constituents, impor-
tant parameters to measure in the waste
include total solids content, pH, biodegrad-
able matter, pathogens, nutrients, metals, car-
bon to nitrogen ratio, soluble salts, and calci-
um carbonate equivalent. These parameters
are summarized in Table 1 and discussed in
the subsequent subsections. In addition to an
initial analysis of these parameters, sample
and characterize the waste on a regular basis
and after process changes that may affect
waste characteristics. This will help deter-
mine whether it is necessary to change land
application practices or consider other waste
management options.

B.     Total  Solids  Content
  Total solids content indicates the ratio of
solids to water in a waste. It includes both
suspended and dissolved solids,  and is usual-
ly expressed as a percentage of the waste.
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


                                                        Protecting Ground Water—Designing A Land Application Program
                                          Table 1
                         Summary of Important Waste Parameters
Waste parameter Significance
Total solids content
Biodegradable organic matter
Nutrients (nitrogen,
phosphorous, and potassium)
Carbon to nitrogn ratio
Soluble salts
Calcium carbonate equivalent
Ground-water constituents
designated in the risk
assessment section including
metals and organic chemicals
Indicates ratio of solids to water in waste and influences
application method.
Controls metals solubility (and therefore mobility of metals toward
ground water) and affects biological processes.
Influences soil's water holding capacity, cation exchange, and other
soil physical and chemical properties, and odor.
Affect plant growth; nitrogen is a major determinant of application
rate; can migrate to and contaminate ground water or cause
phytotoxicity if applied in excess.
Influences availability of nitrogen to plants.
Can inhibit plant growth, reduce soil permeability, and
contaminate ground water.
Measures a wastes ability to neutralize soil acidity.
May threaten public health by migrating to ground water or being
carried off-site by surface water, wind, or vectors.
May present public health risk through ground-water
contamination, direct contact with waste-soil mix, transport by
surface water, and accumulation in plants. Metals inhibit plant
growth and can be phytotoxic at elevated concentrations. Zinc,
copper, and nickel are micronutrients essential to plant growth,
but may inhibit growth at high levels.
total solids content (for some dry, fine, panic-
ulate wastes, conditioning may involve
adding water, such as cement kiln dust).4
   Understanding the total solids content will
help plan appropriate storage and handling
procedures and establish an application rate.
Total solids content also will affect the choice of
application method and equipment. Some
methods, such as spray irrigation, may not
work effectively if the solids content is too
high. If it is low, meaning liquid content is cor-
respondingly high, waste transportation costs
could increase. If the total solids content of the
waste is expected to vary, select equipment to
accommodate materials with a range of solids
contents. For example, selecting spreaders that
will not dog if the waste is slightly drier than
Source: Ag-Chem Equipment Co., Iric.
Reprinted with permission
4Some states consider composted materials to be no longer wastes. Consult with the regulatory agency for
applicable definitions.


Protecting Ground Water—Designing A Land Application Program
                    Source: Ag-Chem Equipment Co., Inc.
                    Reprinted with permission

                    usual will help operations run more efficiently
                    and reduce equipment problems.
                    C     pH
                      A waste's 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 the soil pH range from 5.5 to
                    7.5. If a waste is sufficiently acidic or
                    alkaline5 to move soil pH out of that range, it
                    may hamper plant growth. Acidic waste pro-
                    motes leaching of metals, because most met-
                    als are more soluble under acidic conditions
                    than neutral or alkaline conditions. Once in
                    solution, 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 microorganisms and may increase the
                    mobility of zinc, cadmium, and lead.
                      Waste with a pH of 2 or less or a pH of
                    12.5 or more, meets the definition of haz-
                    ardous waste under federal regulations. If the
                    pH of a waste makes it too acidic for land
                    application, consider 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 as han-
                    dling and storage procedures for a waste are
D.    Biodegradable Organic
   Wastes containing a relatively high per-
centage 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
chemical compounds, such as chelating
agents, that help change nutrients into more
plant-available forms. Biodegradable organic
matter content is typically expressed as a per-
centage of sample dry weight.
   Biodegradable organic matter influences
soil characteristics. Soils with high organic
matter content often have a darker color
(ranging from brown to black), increased
cation exchange capacity—or capacity to  take
up and give off positively charged ions—and
greater water holding capacity. Biodegradable
organic matter also helps stabilize and
improve the soil structure, decrease the den-
sity of the material, and improve aeration in
the soil. In addition, organic nutrients are less
likely 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 for plant growth,
 decomposition rates can vary significantly
 among materials. Food processing residues,
 for example, generally decompose faster than
 denser organic materials, such as wood chips.
 Account for the decomposition rate when
 determining the amount and frequency of
 waste application. Loading the soil with too
 much decomposing organic matter (such as
 by applying new waste before a previous
                    5A pH of 7 is neutral. Materials with pH less than 7 are acidic, while those with pH greater than 7 are


                                                      Protecting Ground Water—Designing A Land Application Program
application of slowly decomposing waste has
broken down) can induce nitrogen deficiency
(see section E. below) or lead to anaerobic
E.      Nutrients
  Nitrogen, phosphorus, and potassium are
often referred to as primary or macronutri-
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
supply nutrients, especially primary nutri-
ents, 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,
may 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 pri-
  mary 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 nitrogen promotes healthy
  growth and imparts a dark green color in
  vegetation. Lack of nitrogen can be identi-
  fied by stunted plant growth and pale
  green or yellowish colored vegetation.
  Extreme nitrogen deficiency may cause
  plants to turn brown and die. On the other
  extreme, excessive nitrogen levels may
  result in nitrate leaching, which can conta-
  minate ground-water supplies.
   Although nitrate poses the greatest threat
   to ground water, nitrogen occurs in a vari-
   ety of forms including ammonium, nitrate,
   nitrite, and organic nitrogen. These forms
   taken together are measured as total nitro-
   gen. As a nutrient management plan is
   developed, consider that nitrogen transfor-
   mations among these forms can continue
   after waste has been applied.

   Phosphorus. Phosphorus plays a role in
   the metabolic process and reproduction of
   plants. When soil contains sufficient quan-
   tities 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.

   Potassium. Potassium is an essential nutri-
   ent for protein synthesis and fluid balance
   in plant growth. As with other nutrient
   deficiencies, symptoms include yellowing,
   burnt, or dying leaves, as well as stunted
   plant growth.  In addition, signs of potassi-
   um deficiency include reduced disease
   resistance and reduced winter hardiness in
   certain plants.

How can I take nutrient levels
into  account?
   Develop a nutrient management plan that
accounts for the amount of nitrogen, phos-
phorus, and potassium being supplied by all
sources at a site.  The deciding nutrient is
often nitrogen; however, do not overlook
loading rates of other nutrients. If waste
application rates are based solely on nitrogen
levels, resulting levels of other nutrients can
exceed crop needs or threaten ground water.
Avoid excessive nutrient levels by monitoring
waste concentrations and soil buildup of
nutrients and reducing the application rate as


• Pro
Protecting Ground Water—Designing A Land Application Program
                      necessary; or by spacing applications to allow
                      plant uptake between applications.
                         Maintaining appropriate phosphorus and
                      potassium levels should be pan of an overall
                      nutrient management plan. The regional,
                      state, or county agricultural extension ser-
                      vices may have already developed materials
                      on or identified software for nutrient manage-
                      ment planning.  Consult with them about the
                      availability of such information. Northeast
                      Regional Agricultural Engineering Services
                      (NRAES) Cooperative Extension, for example,
                      has compiled information on nutrient man-
                      agement software programs.6

                      F.     Metals
                         A number of metals are included in the
                      EPAIWEM for evaluating ground-water risk.
                      Some metals, such as zinc, copper, and man-
                      ganese, are essential soil micronutrients for
                      plant growth. These are often added to inor-
                      ganic commercial fertilizers. At excessive con-
                      centrations, however, some of these metals may
                      be toxic to humans, animals, and plants. High
                      concentrations of copper, nickel, and zinc, for
                      example, 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, evaluate levels of these met-
                      als in waste, soil, and plants from the stand-
                      point of agricultural significance as well as
                      health and environmental risk.
                       How can I  determine acceptable
                       metal concentrations?
                         Using the Tier 1 and II ground-water mod-
                       els will help to identify acceptable metals
                       concentrations. Also consult with the local,
                       state, or regional agriculture extension  center
                       on appropriate nutrient concentrations for
                                                                 plant growth. If the risk evaluation indicates
                                                                 that a waste is appropriate for land applica-
                                                                 tion, but subsequent soil or plant tissue test-
                                                                 ing finds excessive levels of metals, consider
                                                                 pretreating a waste with physical or chemical
                                                                 processes, such as chemical precipitation to
                                                                 remove some metals before application.

                                                                 G.    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 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 deficiencies.
                                                                 This occurs when wastes provide carbon in
                                                                 quantities that microbes cannot process with-
                                                                 out depleting available nitrogen. Soil microbes
                                                                 use carbon to build cells and nitrogen to
                                                                 synthesize proteins. Any excess organic nitro-
                                                                 gen 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-
                                                                 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 Lto 30 to 1—a low
                                                                 nitrogen content—soil micro-organisms use
                                                                 much of the organic nitrogen to synthesize
                       'Nutrient Management Software: Proceedings from the Nutrient Management Software Workshop. To order, call
                       NRAES at 607 255-7654 and request publication number NRAES-100.


                                                      Protecting Ground Water—Designing A Land Application Program
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. As a result, if applying waste based
only on assumed nitrogen mineralization
rates, it is often difficult to ensure that the
soil contains sufficient inorganic nitrogen for
plants at appropriate times. If you are con-
cerned about reductions in crop yield, moni-
tor the soil's carbon to nitrogen ratio and,
when it exceeds 20 to 1, reduce organic
waste application and/or supplement the nat-
urally mineralized nitrogen 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 laboratory  titrations.

H.     Soluble  Salts
  Soluble salts are materials that dissolve in
water or are already in solution in waste.
Major soluble salt ions  include calcium  (Ca2*),
magnesium (Mg2*), sodium (Na+), potassium
(KO, chloride (C1-), sulfate  (SO.2-), bicarbon-
ate  (HCOs-), and nitrate (NQr). The sum of
all salt ions, sugars, and other materials in
solution is referred to as total dissolved solids
(TDS). The soluble salt content of a material
may be determined by analyzing the concen-
tration of the individual constituent ions and
summing them, but this is a lengthy proce-
dure. TDS of soil or waste can  reasonably be
estimated by measuring the electrical conduc-
tivity (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 pri-
mary determinant of its agricultural suitability
for land application, especially 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 (Na4-) relative to diva-
lent ions (Ca2*, Mg2*), may 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
waste or soil, determine the Na*, Ca2*, and
Mg2+concentrations in milliequivalents  per
liter7 for use in the following equation8:
   SAR =


Protecting Ground Water—Designing A Land Application Program
                                                               Table 2
                                                 Salinity Tolerance of Selected Crops
                                                Soil Salinity  (rnmhos/cm)i'that  will result  in:
                               0% yield
50% yield
100% yield
Bermuda grass
Perennial rye
Tall fescue
                     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 11/2 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.
                        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 important is that specific ions can
                     induce plant toxicities or contaminate ground
                     water. Sodium and chloride ions, for exam-
                     ple, can become phytotoxic at high concen-
                     trations. To assess sodic- or toxic-inducing
                     characteristics, 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
                                               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
                                               may increase the  risk of waste constituents
                                               being transported to ground water.
                                                 Since plants vary in their tolerance to
                                               saline environments, plant selection also is
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 (refer to Appendix 1
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
                                         Table 3
             EC and SAR Levels Indicative of Saline, Sodic, and Saline-Sodic Soils
Soil Characterization
Normal Saline Sodic Saline-Sodic
ECa< 4 and
SARb< 13
EC> 4 and
SAR> 13
    Source: Fipps, G. Managing Irrigation Water Salinity In the Lower Rio Grande Valley.
    "In units of mmhos/cm           bdimensionless
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.

  Avoid applying high salt content waste as
much as possible. For saline wastes, a lower
application rate and thorough, tilling or
plowing may help dilute the overall salt con-
tent of the waste by mixing it with a greater
soil volume. To avoid the inhibited germina-
tion associated with saline soils, it also may
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 permeabili-
ty; investigate the EC of a waste as well. Even
if a waste has a high SAR, plants may 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 gypsum
(CaSO4) to irrigation water may also help to
reduce the SAR, by increasing soil calcium
levels. Although this may help address sodi-
um-induced soil structure problems, if choos-
ing to add constituents to alter the SAR, the
EC  will  also need to be monitored to ensure
salinity levels are not increase too much.
I.      Calcium  Carbonate
   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.

J.      Pathogens
   Potential disease-causing micro-organisms or
pathogens, such as bacteria, viruses, protozoa,
and the eggs of parasitic worms, may be pre-
sent in certain wastes. Standardized testing pro-
cedures are available to help determine
whether a waste contains pathogens. Consider
using such tests especially if process knowledge
indicates that a waste might contain pathogens.
Fecal coliform bacteria can be quantified, for
example, by using a membrane filtering tech-
nique, which involves passing liquid waste
through a filter, incubating the filtrate (which


Protecting Ground Water—Designing A Land Application Program
                    contains the bacteria) on a culture medium for
                    24 hours, and then counting the number of
                    bacterial colonies formed.
                      Pathogens present a public health hazard
                    if they are transferred to food or feed crops,
                    contained in run-off to surface waters, or
                    transported away from a land application site
                    by vectors. If pathogen-carrying vectors are a
                    concern at a site, establish measures to con-
                    trol them. For examples of mediods to con-
                    trol vectors, refer to the chapter on operating
                    the waste management system.
                    How can I  reduce pathogenic
                      Methods to reduce pathogenic risk include
                    disinfecting or stabilizing a waste prior to
                    land application. Examples of treatment
                    methods recognized for sewage sludge stabi-
                    lization are included in the sidebar. The ser-
                    vices of a qualified engineer may be neces-
                    sary to design an appropriate