xvEPA
United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
EPA-600/2-83-076
August 1983
Research and Development
Handbook for
Evaluating Remedial
Action Technology
Plans
-------
EPA-600/2-83-076
August 1983
HANDBOOK FOR
EVALUATING REMEDIAL ACTION
TECHNOLOGY PLANS
by
John Ehrenfeld and Jeffrey Bass
Arthur D. Little, Inc.
Acorn Park
Cambridge, MA 02140
EPA Contract 68-01 -5949
EPA Project Officer
Herbert R. Pahren
, c n,,,', -. •-•< r-.-i .••"*"?« Agency
230 South IA ••• • •- - -••'•
CMeago. Illinois bOt-vj-j.
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OH 45268
-------
DISCLAIMER
The information in this document has been funded wholly or
in part by the United States Environmental Protection Agency un-
der Contract 68-01-5949 to Arthur D. Little, Inc. It has been
subject to the Agency's peer and administrative review and has
been approved for publication. The contents reflect the views
and policies of the Agency. Mention of trade names or commer-
cial products does not constitute endorsement or recommendation
for use.
This manual is intended to present information on technol-
ogies that may be applicable to specific problems of controlling
hazardous wastes at disposal sites. It is not intended to cover
any technology exhaustively, nor is the subject of alternative
disposal methods addressed except in the context of remedial
measures at uncontrolled sites. Neither are the topics of
quick- or short-term remedial response actions or management/
manifesting procedures considered to be appropriate for inclu-
sion in this manual.
;»$**
ii
-------
FOREWORD
The Environmental Protection Agency was created because of increasing
public and governmental concern about the nation's environment and its effect
on the health and welfare of the American people. The complexity of the
environment and the interplay among its components require a concentrated and
integrated attack upon environmental problems.
The first step in seeking environmental solutions is research and
development to define the problem, measure its impact and project possible
remedies. Research and development is carried out continually by both
industry and governmental agencies concerned with improving the environment.
Much key research and development is handled by EPA's Municipal Environmental
Research Laboratory. The Laboratory develops new and improved technology and
systems/ to prevent, treat, and manage wastewater and community sources; to
preserve and treat public drinking water supplies; and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This
publication is one of the products of that research — a vital communications
link between the research and the user community.
This document provides an outline of technical information that
potentially could be used to evaluate long term remedial action plans for
controlling or treating wastes or leachates at uncontrolled hazardous waste
sites. It is not a design manual nor does it contain rules or regulations
pertaining to remedial actions.
The intended audience for this document includes those involved in the
review of preliminary engineering reports or formal designs of remedial
actions at the waste sites.
Francis T. Mayo, Director
Municipal Environmental Research Laboratory
111
-------
ABSTRACT
There are four major exposure pathways for uncontrolled
hazardous waste disposal sites:
1. Groundwater/leachate;
2. Surface water;
3. Contaminated soils and residual waste; and
4. Air.
Remedial action technologies are designed to reduce exposure to
humans and the environment to acceptable levels by either con-
taining hazardous materials in place or removing the intrinsic
hazard by decontaminating or physically removing the hazardous
substances.
This report contains information on over 50 remedial action
technologies. A brief description, status, factors for deter-
mining feasibility and reliability, principal data requirements,
and basic information for cost review are given for each tech-
nology. In addition a, general discussion of the major pathways
and associated remedial approaches and of monitoring techniques
has been included.
This report was submitted in fulfillment of Contract No.
68-01-5949 by Arthur D. Little, Inc. under the sponsorship of
the U.S. Environmental Protection Agency. It covers the period
October, 1981 to June, 1982, and work was completed as of Decem-
ber, 1982.
IV
-------
CONTENTS
Section Page
FOREWARD iii
ABSTRACT iv
LIST OF FIGURES viii
LIST OF TABLES xii
ACKNOWLEDGEMENTS xvii
1.0 INTRODUCTION 1
1.1 BACKGROUND 2
1.2 THE NCP PROCESS 3
1.3 REPORT CONTENTS 6
1.4 DESCRIPTION OF THE TECHNICAL RESOURSE
DOCUMENTS 9
2.0 PRINCIPAL MEDIA AND ASSOCIATED REMEDIAL APPROACHES 13
2.1 GROUNDWATER/LEACHATE 17
2.1.1 Containment Techniques 20
2.1.2 Treatment Technologies 34
2.2 SURFACE WATER 39
2.2.1 General Characteristics 41
2.2.2 Surface Water Control Technologies 43
2.3 CONTAMINATED SOIL AND WASTE MATERIALS 47
2.3.1 Removal 50
2.3.2 On-Site Treatment 51
2.3.3 In Situ Methods 55
2.3.4 On-Site Disposal 57
2.4 AIR 57
2.4.1 Gaseous Emissions 57
2.4.2 Fugitive Emissions 62
2.4.3 Odor 64
3.0 CONTROL TECHNOLOGIES 65
3.1 INTRODUCTION 65
,2 GROUNDWATER CONTROL TECHNOLOGIES 65
3.2.1 Slurry Walls 65
3.2.2 Grout Curtains 76
3.2.3 Sheet Pile Cutoff Walls 87
3.2.4 Block Displacement Method (BDM) 91
3.2.5 Groundwater Pumping 100
v
-------
CONTENTS (Continued)
Section
3.2.6 Subsurface Drains 106
3.3 SURFACE WATER CONTROL TECHNOLOGIES 114
3.3.1 Dikes 114
3.3.2 Terraces 124
3.3.3 Channels 134
3.3.4 Chutes and Downpipes 140
3.3.5 Grading 146
3.3.6 Surface Seals 153
3.3.7 Vegetation 169
3.3.8 Seepage Basins and Ditches 179
3.4 SOIL AND WASTE TECHNOLOGIES 186
3.4.1 Excavation 186
3.4.2 Drum Handling 192
3.4.3 Encapsulation 195
3.4.4 Dewatering 197
3.5 AIR CONTROL TECHNOLOGIES 200
3.5.1 Pipe Vents 200
3.5.2 Trench Vents 207
4.0 TREATMENT TECHNOLOGIES 215
4.1 INTRODUCTION , 215
4.2 BIOLOGICAL TREATMENT 215
4.2.1 Activated Sludge 215
4.2.2 Surface Impoundments 232
4.2.3 Rotating Biological Discs 242
4.2.4 Trickling Filters 249
4.2.5 Land Treatment 258
4.3 CHEMICAL TREATMENT 270
4.3.1 Neutralization 270
4.3.2 Precipitation 276
4.3.3 Reduction (for Cr) 281
4.3.4 Wet Air Oxidation 286
4.3.5 Chlorination (For Cyanide Only) 291
4.3.6 Ozonation 296
4.4 PHYSICAL TREATMENT 299
4.4.1 Reverse Osmosis 299
4.4.2 Equalization/Detention 307
4.4.3 Ion Exchange 312
4.4.4 Carbon Adsorption 318
4.4.5 Stripping 330
4.4.6 Sedimentation 339
4.4.7 Dissolved Air Flotation 342
4.4.8 Filtration 346
4.5 DIRECT TREATMENT 355
4.5.1 In Situ Leachate/Groundwater Treatment 355
4.5.2 In Situ Physical/Chemical Treatment 363
vi
TT
-------
CONTENTS (Continued)
Section
4.5.3 On-Site Physical/Chemical Treatment
4.5.4 In Situ Vitrification
4.5.5 Solution Mining (Extraction)
4.5.6 Biodegration
4.5.7 Solidification/Stabilization
4.5.8 Incineration
4.5.9 Thermal Oxidation Systems
4.5.10 Carbon Adsorption For Air Emissions
5.0 MONITORING TECHNIQUES 391
5.1 MONITORING PROGRAM GUIDELINES FOR REMEDIAL
ACTION ASSESSMENT 394
5.2 MONITORING FOR REMEDIAL ACTION EFFECTIVENESS 396
5.3 MONITORING AND SAMPLING TECHNIQUES 397
5.3.1 Monitoring and Procedures to Determine
the Setting 397
5.3.2 Monitoring Procedures for Assessment
of Site-Related Contamination 399
5.3.3 Monitoring Wells 405
GLOSSARY 420
REFERENCES 429
COPYRIGHT NOTICE 438
Vll
-------
FIGURES
Figure Page
1-1 Hazardous Substance Response Sequence (40 CFR
Part 300) 4
1-2 Detailed Sequence-Phase VI-Remedial Action (40
CFR Part 300.68) 5
2-1 Environmental Pathways from a Generalized Haz-
ardous Waste Site 14
2-2 Schematic Diagram of Exposure Pathways 15
2-3 Leachate Migration and Groundwater Contamina-
tion 19
2-4 Water Table Adjustment by Extraction Wells 22
2-5 Aquifer Response to an Infinite Barrier 24
2-6 Effect on Groundwater Level of Upgradient Bar-
rier 26
2-7 Effect on Groundwater Level of Barrier Sur-
rounding Waste 28
2-8 Effect of Leaking Surface Impoundment on
Groundwater Conditions 30
2-9 Layered Aquifer System 32
2-10 Alternative Treatment Sequences for an Aqueous
Mixture of Metals and Chlorinated Degreasing
Solvents 54
3-1 Construction of a Bentonite Slurry Wall 69
3-2 Theoretical Relationship Between Wall Permea-
bility of Filter Cake and Backfill 70
3-3 Permeability of Soil-Bentonite Backfill Related
to Fines Content 73
Vlll
-------
LIST OF FIGURES (Continued)
Figure Page
3-4 Typical Three-Row Grid Pattern for Grout Cur-
tain 77
3-5 Viscosities of Various Grouting Materials as a
Function of Grout Concentration 82
3-6 Correlations Between Soil Grain Size, Permea-
bility and Potential Dewatering Methods 83
3-7 Soil Grain Size Limits for Grout Injectability 84
3-8 Sheet Piling Section Profiles 88
3-9 Block Displacement Method 93
3-10 Wellpoint Dewatering System 104
3-11 Spacing Equation Diagram 110
3-12 Typical Dike Cross Section 116
3-13 Typical Terrace Cross Sections 128
3-14 Values of X in Equation VI = XS+Y 130
3-15 Typical Channel Cross Sections 138
3-16 Downpipe 142
3-17 Paved Chute 144
3-18 Surface Water Controls Upslope of Waste Site 148
3-19 Typical Surface Seals 156
3-20 Seepage Basin: Shallow Depth to Groundwater 182
3-21 Seepage Ditch with Increased Seepage Efficiency 183
3-22 Long-Term Acceptance Rate of Effluent By Soil 184
3-23 Design Configuration of Pipe Vents 201
3-24 Radius of Influence of Pipe Vent 204
3-25 Design Configuration of Trench Vents 210
4-1 Typical Activated Sludge System 225
ix
-------
LIST OF FIGURES (Continued)
Figure Page
4-2 Aerated Surface Impoundment 235
4-3 Rotating Biological Disc Treatment Schematic 245
4-4 Construction Costs for Rotating Biological
Discs 250
4-5 O&M Costs for Rotating Biological Discs 250
4-6 Trickling Filter Treatment System Schematic 251
4-7 Optimal Dimensions of Trickling Filters 257
4-8 Land Application Approaches 261
4-9 Schematic of a Leachate Recycle System 262
4-10 Neutralization Treatment System Schematic Dia-
gram 271
4-11 Neutralization Curve 274
4-12 Solubility of Metal Hydroxides and Sulfides 278
4-13 Chromium Reduction Treatment System 283
4-14 Schematic of Wet Air Oxidation 288
4-15 Time-Temperature Effect on the Degree of Oxida-
tion 290
4-16 Cyanide Chlorination Treatment 292
4-17 Membrane Module Configurations 302
4-18 Granular Activated Carbon System Configuration 321
4-19 Schematic of Carbon Adsorption Isotherm 326
4-20 Schematic Breakthrough Curves for Columns in
Series 327
4-21 Schematic of Bed Depth Versus Service Time 328
4-22 Construction Costs for Tertiary Activated Car-
bon Treatment 331
x
-------
LIST OF FIGURES (Continued)
Figure Page
4-23 O&M Costs for Tertiary Activated Carbon Treat-
ment 331
4-24 Air Stripping Towers 333
4-25 Typical Steam Stripping System 334
4-26 Capital Costs of Ammonia Stripping System 338
4-27 Operation and Maintenance Costs of Ammonia
Stripping System 338
4-28 Granular Media Filter 348
4-29 Rotary Drum Vacuum Filter 349
4-30 Filter Press 350
4-31 Installation of a Permeable Treatment Bed 357
4-32 Cross Section of Landfill Treated by Chemical
Injection 358
4-33 Capital and Operating Costs for Non-Regenera-
tive Carbon Adsorption Systems Treating Vent
Gas Containing 50 PPM Trichloroethylene 390
5-1 Placement of Monitoring Wells 397
5-2 Detection of a Leachate Plume Using an Electric
Well Log 400
5-3 Single-Screened Well 406
5-4 Multiple-Screened Well Pump 407
5-5 Well Cluster 408
5-6 Piezometer Well 409
XI
-------
LIST OF TABLES
Table Page
2-1 Applicability of Unit Processes to Leachate or
Groundwater Contaminants 40
2-2 Surface Water Technologies 44
2-3 Sources of Gaseous Emissions 58
2-4 Effect of Different Covers on Landfill HCB Va-
por Emissions 61
2-5 Odor Control Agents 64
3-1 Control Technology Data Requirements 66
3-2 Primary Data Sources 67
3-3 Permeability Increase Due to Leaching with
Various Pollutants 74
3-4 Types of Grout 79
3-5 Grout Properties 81
3-6 Unit Costs of Grouts 87
3-7 Sheet Piling Unit Costs 91
3-8 Slurry Characteristics for the Block Displace-
ment Method 98
3-9 Unit Costs for Well Installation 107
3-10 Unit Costs for a Subsurface Drainage System 112
3-11 Dike Classification 115
3-12 Recommended Dike Top Widths 118
3-13 Recommended Dike Side Slopes 119
Xll
-------
LIST OF TABLES (Continued)
Table Page
3-14 Soil Characteristics 120
3-15 Runoff Dike Requirements 122
3-16 Unit Costs Associated with Surface Water Di-
version and Collection Structures 125
3-17 Maximum Terrace Grades 132
3-18 Values of Manning's n for Various Channel Sur-
face Materials 136
3-19 Permissible Velocities for Channels Lined with
Vegetation 137
3-20 Typical Channel Design Requirements 139
3-21 Chute Bottom Width and Drainage Area 143
3-22 Downpipe Diameter and Drainage Area 145
3-23 Grading Technique 147
3-24 Compaction Equipment 150
3-25 Unit Costs for Grading 154
3-26 Primary Function of Cover Layers 157
3-27 Ranking of USCS Soil Types According to Per-
formance of Cover Function 158
3-28 Chemical Additives for Cover Soil 159
3-29 Products Recommended for Priority Cover 165
3-30 Unit Costs for Surface Seals 170
3-31 Characteristics of Commonly Used Grasses 172
3-32 Characteristics of Commonly Used Legumes 174
3-33 Characteristics of Commonly Used Trees 175
3-3"4 Characteristics of Commonly Used Shrubs 176
3-35 Unit Costs for Revegetation 180
Xlll
-------
LIST OF TABLES (Continued)
Table Page
3-36 Excavation Equipment Characteristics 188
3-37 Production Rates for Excavation Equipment 189
3-38 Unit Costs for Excavation 193
3-39 Unit Costs of Pipe Vent Components 208
3-40 Costs for a Forced Pipe Vent System 209
3-41 Unit Costs for Trench Units 213
3-42 Costs of Trench Vents for a Disposal Site 214
4-1 Treatment Process Applicability Matrix 216
4-2 Treatability Classification of the 129 Prior-
ity Pollutants 217
4-3 Treatment Technology Data Requirements 223
4-4 Summary of Aeration Methods 226
4-5 Estimated Unit Costs of Activated Sludge Sys-
tems 233
4-6 Typical Values of Design Parameters for Sur-
face Impoundments 240
4-7 Cost Estimates for Aerated Surface Impound-
ments 243
4-8 Operating Cost Estimates for Anaerobic Diges-
tion System 244
4-9 Design Criteria for Rotating Biological Disks 247
4-10 Design Criteria for Trickling Filters 254
4-11 Cost Estimates for Trickling Filters 259
4-12 Removal Efficiency for Land Treatment Options 263
xiv
-------
LIST OF TABLES (Continued)
Table Page
4-13 Comparative Characteristics of Land Applica-
tion Approaches 266
4-14 Essential Consideration in a Comprehensive
Testing Program for Appraising Waste-Site
Interactions 268
4-15 Site Selection Factors and Criteria for Efflu-
ent Irrigation 269
4-16 Precipitation, Flocculation, and Sedimentation
Cost Estimates as a Function of Size 282
4-17 Estimated Operating Costs for Reduction 287
4-18 WAO Efficiency for Ten Priority Pollutants 289
4-19 Estimated Costs for Chemical Oxidation 295
4-20 Comparison of Reverse Osmosis Module Configu-
rations 303
4-21 Reverse Osmosis Membrane Materials 304
4-22 Estimated Reverse Osmosis Plant Costs 308
4-23 Costs of Equalization Facilities 312
4-24 Removal Data for Electroplating Wastewater
Streams - 314
4-25 Ion Exchange System 315
i
4-26 Ion Exchange Cost Estimates 319
4-27 Contacting Systems 322
4-28 Properties of Several Comercially Available
Carbons 325
4-29 Estimated Costs for Activated Carbon Removal
of Phenol 332
4-30 Capital Investment for a 200 GPM Steam Strip-
per 339
xv
-------
LIST OF TABLES (Continued)
Table Page
4-31 Operating Costs for a 200 GPM Sour Water Steam
Stripper 340
4-32 Potential Applicability of Filtration to
Various Forms of Hazardous Wastes 351
4-33 Major Design and Performance Variables for
Filtration 352
4-34 Vacuum Filtration Cost Estimates as a Function
of Size 356
4-35 Costs of Potential In-Situ Neutralization/
Detoxification Chemicals 364
4-36 Costs for In-Situ Detoxification of Cyanide 365
4-37 Unit Costs for Extraction Chemicals 372
4-38 Summary of Treatable Waste Forms and Inter-
fering Waste Classes 376
4-39 Costs of Chemical Fixation for a Disposal Site 379
4-40 Key Features of Major Types of Incinerators 380
4-41 Unit Costs of Waste Disposal by Incineration 384
4-42 Retentivity Factors of Organic Compounds 388
5-1 Monitoring Program Design Considerations 393
5-2 Drilling Techniques 413
5-3 Slot Size 415
5-4 Principal Data Considerations for Monitoring
Wells 417
5-5 Cost Estimates for Monitoring Wells 418
xvi
-------
ACKNOWLEDGMENTS
Arthur D. Little, Inc. (ADL) prepared this document for the
EPA's Office of Research and Development (ORD) in fulfillment of
Contract No. 68-01-5949 Task Order No. 13. Ms. Wendy Davis-
Hoover and Mr. Herbert Pahren of MERL were Project Officers.
Dr. John R. Ehrenfeld, ADL's Project Manager, and Mr. Jeffrey M.
Bass were the principal contributors and editors. Mr. Alan
Preston and Dr. William Tucker were also principal contributors.
Other contributors include Ms. Marie Chung, Mr. Anthony Colella,
Dr. Waren Lyman, Ms. Pamela McNamara, and Ms. Leslie Nelken.
Mr. Donald Banning, Municipal Environmental Research Laboratory,
Cincinnati, Ohio and Mr. Richard Stanford, Office of Emergency
and Remedial Response (OERR) are acknowledged for their direc-
tion of and valuable contributions to this report.
A peer review of the final draft was carried out by in-
dividuals associated with: 1) Illinois Institute of Technology;
2) NUS Corporation, PEC Division; 3) U.S. Army Toxic and Haz-
ardous Materials Agency, Aberdeen Proving Grounds; 4) Chemical
Manufacturers Association; 5) JRB Associates; and 6) Office of
Emergency and Remedial Response, USEPA. As a result of the com-
ments the document was changed, as appropriate. The helpful
suggestions of these reviewers are gratefully acknowledged.
xvii
-------
T
-------
SECTION 1
INTRODUCTION
The development of remedial action plans and the ultimate
implementation of those plans follows a series of steps set out in
the National Contingency Plan (NCP), as described in more detail in
Part 1.1, below. Early in the process, alternative technological
approaches are first identified and then screened through a net of
increasing stringency regarding cost and effectiveness. The U.S.
Environmental Protection Agency (EPA) has developed a substantial
body of information on the various technological alternatives, most
recently culminating in the publication "Handbook for Remedial.,,
Action at Waste Disposal Sites." The Handbook contains extensive
information about the many potential technologies and is organized
to assist planners and engineers in selecting and weeding out appro--'
priate approaches.
As the plans evolve and get closer to implementation, they must
be examined for technical and economic feasibility and conformance
with the guidelines in the NCP. The evaluation process implied is
carried out by many parties: the EPA, state agencies, responsible
disposers and facility operators, and the public at large. This
report has been prepared to support this evaluation. Data on the
same large set of potential technologies contained in the Handbook
above are organized to assist reviewers in determining if the engi-
neers and designers have used reasonable, conventional data and
assumptions in the development process. This publication is not a
design manual although, where practical, simple formulas and other
information which designers generally use are included as a basis of
comparison and checking.
The primary sources of the data include the series of federal
publications known as "Technical Resource Documents" (TRDs), and
data from several recent EPA projects on remedial activities at haz-
ardous waste sites. One objective of this project was to make infor-
mation in the TRDs available and useful to all participants in
remedial action activities at hazardous waste sites. A limited,
general review of the literature and state-of-the-art was carried
out. The additional information was included to enhance the data
-------
from the TRDs and to complement them, particularly with regard to
cost. Though this report is aimed primarily at cleanup activities
involving permanent remedy, several of the technologies described
here may also be used in emergency settings.
1.1 BACKGROUND
The Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA, also commonly known as Superfund),
was passed late in 1981 to provide for (1) cleanup and emergency
response for hazardous substances released into the environment,
and (2) cleanup of inactive hazardous waste disposal sites. Section
105 of the Act directs the President to prepare a National Contin-
gency Plan (NCP) to establish procedures and standards for respond-
ing to releases of hazardous substances. The NCP must include,
among other things, methods for evaluating (including analyses of
relative cost) and remedying any releases or threatened releases of
hazardous substances, and means of assuring that remedial measures
are cost effective.
After receiving comments on several drafts, EPA published the
NCP in final form July 16, 1982 (40 CFR 300). The NCP describes pro-
cedures to develop and implement plans for remedying releases of
hazardous substances. The NCP implements requirements in CERCLA and
in the Clean Water Act (CWA). The NCP process, briefly summarized
below, incorporates a number of judgements and decisions based on
technical grounds.
These judgements and decisions occur at several steps along the
process and are made by the lead agency (EPA or a state depending on
the existence and nature of the agreement between EPA and the
state), private responsible parties developing remedial action
plans, consultants and engineers supporting the above interests,
and other interested parties. This guide is designed to furnish
technical information to support the NCP process and to assist those
involved in making judgements and decisions.
Other documents have been prepared to support the process. In
particular, as noted in the preamble to the NCP, "... the EPA has
developed a technical handbook which can be utilized along with this
section of the NCP (300.70) to provide more technical information on
the circumstances and types of releases in which these methods may
be successfully employed." The manual is entitled "Handbook for
Remedial Action at Waste Disposal Sites." This guide complements
the Handbook and is oriented toward the evaluation of conceptual
-------
designs, rather than toward developing the designs. The Handbook is
frequently referenced below.
This report also draws extensively on the TRDs. As part of its
activities under a related act, (The Resource Conservation and
Recovery Act of 1976, or RCRA) the EPA has prepared a series of pub-
lications, the TRDs, to support the permitting process required by
this legislation. The TRDs describe current technologies in several
broad categories related to hazardous waste disposal facilities
(landfills, surface impoundments, and land treatment facilities).
Many of the technologies for use at controlled hazardous waste dis-
posal sites are applicable to remedial activities at uncontrolled,
inactive sites. The TRDs represent a broad source of information
that informally supports activities under the NCP for evaluating,
planning, and implementing actions at uncontrolled sites.
The TRDs have a specific role in the RCRA process. They are
designed to assist permit writers in arriving at a logical, well
defined and well documented decision. With respect to remedial
activities, they serve only as a potential source of information to
the participants in the process. This report gives them easy access
to the information contained in the TRDs and makes these documents
more useful to them.
1.2 THE NCP PROCESS
The key parts of the NCP bearing on remedial action are con-
tained in Subpart F. Subpart F identifies the state role (Section
300.62) and a phased procedure for responding to the release of haz-
ardous substances (Sections 300.63 to 300.70). Figure 1-1 illus-
trates the flow of the phases. The major focus of this report is on
Phase VI - Remedial Action (Section 300.68). Figure 1-2 illustrates
the Phase VI process in detail and indicates the steps associated
with technical criteria for which the information in this document
has been developed and organized.
The first several steps are designed to elucidate the nature of
the problems at a site, to determine the major courses of action, and
to develop a series of potentially cost-effective alternatives dic-
tated by those actions. The latter steps, beginning with the ini-
tial screening of alternatives, are designed to select the
cost-effective alternative using the set of criteria specified in
the NCP.
-------
FIGURE 1-1
HAZARDOUS SUBSTANCE RESPONSE SEQUENCE (40 CFR PART 300)
Phase 1
Discovery or
Notification
(300.63)*
Phase II
Preliminary
Assessment
(300.64)
Head Agency
Phase III
Immediate
Removal
(300.65)
Phase IV
Evaluation and Determination
of Appropriate Response
Planned Removal and
Phase V
Planned
Removal
(300.67)
^
See Figure 1-2
for Detail
Phase VII
Documentation and
Cost Recovery
(300.69)
*Refers to the section of the NCR in 40 CFR part 300.
-------
FIGURE 1-2
DETAILED SEQUENCE-PHASE VI-REMEDIAL ACTION (40 CFR PART 300.68)
Funding
300.62
300.68(b),(c),(k)
Development
of
Alternatives
300.68(g)
Factors to Determine
Appropriate Extent of
Remedial Action
300.68(e
• Cost*
• Effects of the alternative*
• Acceptable engineering practice"
Refinement and specification
Use of established technology*
Detailed cost
Engineering implementation or
constructibility*
Technical effectiveness compared
to other alternatives*
Analysis of adverse impacts
• Lowest cost
• Technical feasibility and reliability*
• Mitigates and minimizes damage,
provides adequate protection
*lndicates where information in this report may be useful.
**Referenced to Section of 40 CFR Part 300.
-------
The criteria include several that are related to technical fea-
tures of the conceptual design in relationship to site-specific
characteristics (the factors identified with an asterisk in Figure
1-2). Judgements as to the degree which proposed plans conform to
the criteria must be based on project-specific designs and analyses.
But there are a number of general, technology-specific data and
engineering considerations which can be used to evaluate the plans,
to determine their appropriateness, and to ensure that they have
been developed from sound engineering principles using reasonable
cost estimates.
More specifically, this guide provides data to support the
analysis and evaluation of:
• Feasibility, including:
- acceptability (relevance to the particular pro-
ject)
- implementability or contructibility
• Effectiveness, including reliability
• State of Development
• Cost
1.3 REPORT CONTENTS
Section 2 describes general approaches to remedy problems in
five media that can become contaminated by hazardous substances
released at an uncontrolled site. The media are
groundwater/leachate, surface water, soil, waste, and air. Sec-
tions 3 and 4 describe individual technologies and engineering meth-
ods. Section 3 describes technologies for the physical control and
containment of hazardous constituents in the five media above. Sec-
tion 4 describes treatment technologies for leachate, waste, and
contaminated soil. Information in Section 3 and 4 is presented in
the following format:
• Description—A brief, qualitative discussion of the tech-
nology and the principles on which it is based.
• Status--A measure of the availability of the technology and
degree to which it has been demonstrated for hazardous
waste remedial actions. Conventional, demonstrated means
-------
the technology is widely used and has been applied success-
fully at uncontrolled sites or under equivalent circum-
stances. Conventional, undemonstrated refers to
technologies in general use, but which have yet to be
applied to an uncontrolled site or under sufficiently simi-
lar circumstances. Developmental refers to techniques
currently in the later stages of development but not yet
generally available. Some of the developmental methods are
being tested at uncontrolled sites. Conceptual refers to
technologies described in the literature as possibilities
or as yet in early (lab or pilot) stage of research and
development.
Feasibility and Effectiveness--A discussion of the techni-
cal factors important in understanding and reviewing the
technology. This part gives background necessary for eval-
uating technology design plans and identifies areas of par-
ticular concern. For example, the effect of waste
constituents on backfill and slurry materials is critical
to the effectivenss of a slurry wall. The contents of this
part vary considerably from technology to technology
reflecting the complexity of the technology and the sources
of information used in preparing this report. This part
also contains a short discussion of special precautions to
be taken in using or of limitations of the technology being
discussed.
Design Basis--A summary of the major factors which deter-
mine the performance of treatment technologies. This part,
which is unique to Section 4, is used for the convenience of
the reader to separate basic design information from the
technical concerns of implementing leachate treatment
technologies. Where possible, equations relating design
parameters to desired performance and site conditions are
provided in summarized form. Otherwise, the relationships
are described in qualitative terms.
Principal Data Requirements--The principal site-specific
data necessary for the design of the technology are noted.
The data noted must be obtained in the site investigation or
in laboratory based studies. The evaluation criteria or
performance-related factors most directly related to each
major data requirements is noted in parentheses following
the data item. A summary of the data requirements common to
all of the technologies in a section is provided at the
beginning of Sections 3 and 4. The discussion for each
technology lists the primary data concerns, expands on the
summary table, and incorporates other important data needs.
In addition, Table 3-2 at the beginning of Section 3 summa-
rizes some of the conventional sources of these data.
-------
• Elements of Cost Review--Information for analyzing tech-
nology cost estimates. Each cost discussion is divided
into three parts. Components lists the major components of
cost, including those which involve initial construction
and capital costs, and those which involve ongoing opera-
tion and maintenance (O&M) costs. Major Factors lists the
characteristics of the technology as designed for a given
site (e.g., size, material availability, pretreatment
requirements) that most affect overall cost. Data provides
information on unit and total costs associated with the
technology. Cost data provided has been updated from
available sources to 1982 dollars using the following con-
ventional indices:
Marshall & Stevens Installed Equipment 739
(1st Qtr. 1982)
Engineering l^Iews Record - Construction 3821.79
(6/17/82)
Engineering News Record - Building Cost 2227.66
(6/17/82)
Chemical Engineering Plan Construction 311
(1st Qtr. 1982)
EPA Sewage Treatment Plan Construction 412
Hourly Earning Index (Chemical Eng'-g Progress) 19.60
Other assumptions used in determining 1982 costs include:
- Electricity Costs: $.04/Kwhr unless otherwise
noted.
- Items such as contingency or overhead allowance,
which are highly variable, are generally not
included in the estimates. Tables 3-40, 3-42, and
4-39, however, do include contingency and overhead
allowance to show how these items can affect cost.
- Items such as laboratory and field testing, tech-
nology design or other preliminary analyses are
generally not included in cost estimates.
In general, data in this part are highly variable
reflecting differences in sources used. Many of the costs
for leachate treatment technologies, for example, are based
on information developed in industrial or municipal set-
-------
tings at much larger scale than may be required for remedial
action. Cost information, therefore, should be used only
for rough estimating purposes, unless the actual site con-
dition closely resemble the assumed cost basis.
Section 5 presents a general discussion of monitoring tech-
niques for use during remedial activities and during the
post-closure custodial period. A discussion of monitoring wells in
the format of Sections 3 and 4 is also provided.
The report's organization by media was chosen to help direct
attention to the group of technologies most relevant to the problems
identified at a particular site. The technology discussions present
information in a concise format, relying heavily on figures, tables,
and lists to allow easy access to information needed to evaluate
remedial action technology plans.
1.4 DESCRIPTION OF THE TECHNICAL RESOURCE DOCUMENTS
The eleven TRDs now available, either in draft or final versions
are briefly described below. These reports are referred to through-
out as TRD 1, TRD 2, etc. The formal references appear in each para-
graph below. The descriptions marked with an asterisk have been
taken verbatim from TRD 7.
TRD 1*-- The manual "Evaluating Cover Systems for Solid
and Hazardous Waste" is intended for use by the regional offices in
their evaluation of applications from owners/operators of solid and
hazardous waste disposal areas. More specifically, it is a guide
for evaluation of closure covers on solid and hazardous wastes. The
manual provides a guide to the examination of soil, topographical
and climatological data, closure cover evaluation, recommendations,
and a discussion of post-closure plans (Lutton, 1980) .
TRD 2*-- The document "Hydrologic Simulation on Solid
Waste Disposal Sites" presents an interactive computer program for
simulating the hydrologic characteristics of a solid and hazardous
waste disposal site operation. Using minimal input data from the
user, the model will simulate daily, monthly, and annual runoff,
deep percolation, temperature, soil-water, and evapotranspiration.
The manual provides sufficient information and commands so that an
inexperienced user may perform the operation. The model is designed
for conversational use -- that is, interaction with the computer is
direct and output is received immediately (Perrier and Gibson,
1980).
-------
TRD 3*-- The "Landfill and Surface Impoundment Performance
Evaluation" manual is intended to provide guidance in evaluating
designs to predict the movement of liquids through and out of a sur-
face impoundment and landfill. It includes a discussion of accept-
able operating procedures, design configurations, analysis
procedures, and techniques for interpretation of results as they
apply to impacts on ground and surface water (Moore, 1980).
TRD 4*-- "Lining of Waste Impoundment and Disposal Facili-
ties" provides information on performance, selection., and installa-
tion of specific liners and cover materials for specific disposal
situations, based upon the current state-of-the-art of liner tech-
nology and other pertinent technology. It contains descriptions of
wastes and their effects on linings; a full description of various
natural and artificial liners; liner service life and failure mech-
anisms; installation problems and requirements of liner types;
costs of liners and installation; and tests that are necessary for
preinstallation and monitoring surveys (Matrecon, Inc., 1980).
TRD 5*-- The manual "Management of Hazardous Waste Leach-
ate" presents management options that a permit writer or hazardous
waste landfill operator may consider in controlling a leachate prob-
lem. The manual contains the following: a general discussion of
leachate generation; a section on leachate composition providing
the permit writer with possible guidelines for determining the rela-
tive hazard of a particular leachate; a discussion of five potential
management options for the off-site treatment of leachate or the
on-site treatment of hazardous waste; and a discussion of treatment
technologies that, on a laboratory scale, have demonstrated reason-
able success in treating leachate (TSA Division of Michael Baker,
Inc., 1980).
TRD 6*-- The "Guide to the Disposal of Chemically Stabi-
lized and Solidified Wastes" provides guidance to waste generators
and regulatory officials in the use of chemical
stabilization/solidification techniques for limiting hazards posed
by toxic wastes in the environment. The current state and perform-
ance of hazardous waste disposal and long-term storage techniques
are discussed. In addition to a discussion of major chemical and
physical properties of treated wastes, a list of major
stabilization/solidification technology suppliers and a summary of
each process are provided (Malone et al. , 1980) .
TRD 7*-- The manual "Closure of Hazardous Waste Surface
Impoundments" describes and references, the methods, tests, and
procedures involved in closing a site in such a manner that (a) mini-
10
-------
mizes the need for further maintenance, and (b) controls, minimizes,
or eliminates, to the extent necessary to protect human health and
the environment, post- closure escape of hazardous waste, hazardous
waste constituents, leachate, contaminated rainfall, or waste
decomposition products to ground water, surface waters, or the
atmosphere. Problems that have been overlooked in abandoned
impoundments and have caused environmental degradation are dis-
cussed. The techniques involved are -pertinent to closing an
impoundment either by removing the hazardous wastes or by consol-
idating the waste on site and securing the site as a landfill.
Technical criteria for implementing the closure, specifically those
regarding aspects substantially different from a landfill, are giv-
en. Relevant literature or procedures are documented for more
in-depth review as necessary (Wyss, et al., 1980).
TRD 8*-- The document entitled "Hazardous Waste Land
Treatment" presents a dynamic design approach for land treatment
facilities. This design strategy is based upon sound environmental
considerations and is structured into a total system approach. The
manual discusses site assessment procedures aimed at selecting
acceptable locations. This site assessment procedure consists of
(1) technical consideration of site characteristics and (2) socio-
graphical considerations of area land use. In addition, the manual
describes specific land treatment components and explains why they
are important to an effective design. These components include:
the land treatment medium, hazardous waste stream, preliminary
tests and pilot experiments on waste-soil interactions, facility
design and management, monitoring, changing wastes, contingency
planning, and site closure (K.W. Brown & Assoc., 1980).
TRD 9-- "Soil Properties, Classification and Hydraulic
Conductivity Testing" is a compilation of available methods for the
measurement of saturated and unsaturated hydraulic conductivity
(permeability) of soils. Seventeen methods in the categories of
laboratory, field, and miscellaneous procedures are discussed.
Background information on relevant soil properties and classifica-
tion systems is also given (Roberts and Nichols, 1980).
TRD 10-- The "Solid Waste Leaching Procedures Manual"
addresses the prediction of leachate mixing and movement in ground-
water. In particular, the effect of groundwater mixing on leachate
contaminant concentrations, the direction and manner of leachate
plume travel, and the appropriateness of various groundwater models
are considered. Two approaches for use by the permit writer are pre-
sented: the Site Rating System, a qualitative and parametric
approach; and the Plume Rating System, a more quantitative approach
(Pettyjohn et al. , 1980).
11
-------
TRD 11-- The manual "Evaluation of Closure and
Post-Closure Care Plans for Hazardous Waste Landfills" describes
the general factors that should be considered in preparing and eval-
uating landfill closure plans. Current state-of-the-art knowledge
with respect to the technologies that are applicable to closure and
post-closure of hazardous waste landfills is presented. A synopsis
of important regulations and a comprehensive example for closure and
post-closure care of a hypothetical landfill are also given (SCS
Engineers, 1982).
12
-------
SECTION 2
PRINCIPAL MEDIA AND ASSOCIATED REMEDIAL APPROACHES
Developing a cost-effective remedial response for uncontrolled
releases of hazardous wastes requires knowledge of the settings in
which various problems occur and of the options to deal with those
particular problems. This chapter describes the major types of
problem settings, identifies the most significant site-specific
features bearing on the choice of remedy and describes the major
classes of remedial actions. Sections 3 and 4 present more detailed
information and data describing the many individual remedial tech-
niques. Figure 2-1 depicts the environmental setting for a
generalized uncontrolled disposal site, located above the water
table. Potential pathways to human and ecological receptors are
shown in Figure 2-2. A major variant would place the waste mass
below the water table, in which case the leachate plume and ground-
water are always coincident. The exposure pathways are essentially
the same in both cases, but the applicability of a number of poten-
tial remedies is quite different in the two cases.
This report focuses on remedying hazards due to the migration or
potential migration of toxic materials from the disposal site
through a series of environmental pathways. Mitigating hazards due
to the corrosivity, ignitability and reactivity characteristics of
waste can also be accomplished by some of the treatment methods dis-
cussed; corrective technologies for these types of problems
(corrosivity, etc.) plus potential exposure by direct contact are
often included in emergency response programs preceding remedial
actions and are described in the literature on that subject. Emer-
gency response is not discussed in detail here; the emphasis is on
long-range remedial actions. Figure 2-1 indicates that potential,
hazards at uncontrolled disposal sites can and generally do involve
multiple media. As a result, the remedial action programs must
include an integrated attack on the underlying problems. Remedial
action can follow two main approaches:
I. Contain the hazardous materials, preventing exposure to
human or ecological species.
13
-------
FIGURE 2-1
ENVIRONMENTAL PATHWAYS FROM A GENERALIZED HAZARDOUS WASTE SITE
Municipal
Water Supply
-------
FIGURE 2-2
SCHEMATIC DIAGRAM OF EXPOSURE PATHWAYS
Volatile/Particulate
Air Emissions
Air
WASTE
Runoff
Uptake by
Plants, Animals
Food Chain •
t
Surface
Water
Leaching
Groundwater
Inhalation
Volatilization
•Ingestion
Drinking
Water
t
-------
2. Remove the intrinsic hazard; i.e., decontaminate or phys-
ically remove the hazardous substances at the source or in
the contaminated pathway.
The first approach can reduce hazards to an acceptable level, in
the short-run, but may leave questions of the long-run risks arising
from failures in the containment system (for example, leaks in a
liner) or from natural phenomena (for example, earthquakes). Phys-
ical removal of hazardous materials to another site provides a
long-term, essentially permanent, solution at the uncontrolled
site, but transfers many of the inherent problems to the new site, in
addition to creating new risks due to removal and transportation.
Since hazardous waste treatment, disposal and storage facilities
must now operate under RCRA and perhaps state and local regulations
as well, the potential risks to human health and the environment
should be reduced to acceptable limits at the new site. Decontam-
ination at a site, if effective, can provide the same long-term
remedy without transferring the hazards off-site. But this approach
may be expensive and difficult to apply at sites with extensive soil
and water contamination. In many cases, a combination of the fore-
going two general approaches may be the most effective; e.g., a
containment system to limit the extent of environmental contam-
ination and potential exposure, and a long-term decontamination
system to eliminate the source of the hazard.
This report, by design, treats problems and remedial action
technologies in a general sense, organized as noted below by major
exposure pathways and, further, by broad classes of potentially
applicable remedial approaches. The data and descriptive informa-
tion presented in this introductory chapter and in the subsequent
discussions of individual technologies are generalized and do not
reflect the variability of problems from site-to-site nor the par-
ticular design configuration appropriate for a given site. There
will be many site-specific exceptions to the general considerations
presented below that may render a usually appropriate technology
impractical or ineffective and, vice versa, may promote the attrac-
tiveness and feasibility of concepts not usually associated with the
type of problem being addressed.
The remedial action technologies are organized, both in this
section and also in the following two sections, on Control Technolo-
gies and Treatment Technologies, according to the type of exposure
pathway with which each technology is most conventionaly
associated. Four major exposure pathway classes used are:
1. Groundwater/Leachate;
16
-------
2. Surface Water;
3. Soil and Residual Waste Materials; and
4. Air.
Contaminated sewer and water lines, additional pathways found at
some sites, are not discussed in this report. Each of the four
classes is described in the following sub-sections.
No site is likely to correspond exactly to any of the environ-
mental settings described below. Many problems involve combina-
tions of contaminated pathways. Geological and hydrogeological
characteristics, particularly, are highly site-specific. As a con-
sequence, project-by-project analyses are essential in the develop-
ment and evaluation of remedial action alternatives. The general
data in this report can be supplemented in the future with documen-
tation of actual experience at sites. That kind of information is
now beginning to appear in the general engineering literature at an
increasing rate.
2.1 GROUNDWATER/LEACHATE
Groundwater contamination is the most commonly encountered
problem at existing uncontrolled hazardous waste disposal sites.
Groundwater contamination results from the migration of leachate
which is defined under RCRA as "any liquid, including any suspended
components in the liquid, that has percolated through or drained
from hazardous wastes. " (Fed. Reg. 45, 33075, May 19, 1980).
Groundwater contamination may occur at a wide variety of waste
management facilities and disposal sites including:
1. storage and treatment facilities;
2. landfills;
3. surface impoundments;
4. mines;
5. surface waste piles; and
6. land treatment facilities.
17
-------
Figure 2-3 illustrates potential patterns of leachate migration and
ensuing groundwater contamination that can occur relative to the
water table.
Exposure to the pollutants in leachate can occur in a variety of
ways, as shown in Figures 2-1 and 2-2, and described below.
1. The leachate plume in the groundwater may be drawn into
wells used for drinking water supply, crop irrigation, food
processing, etc.;
2. The leachate plume may intersect a surface water body (for
example, a reservoir or river) which, besides supporting
biota (thus affecting the food chain), may serve as a pota-
ble water supply;
3. Leachate from a surface dump may appear in surface runoff
which may come in direct contact with humans, may contam-
inate surface crops, or pollute nearby surface waters; or
4. Vapors from volatile chemicals in the leachate may diffuse
up through the soil surface and lead to exposure via inhala-
tion; entry of vapors directly into the basements of build-
ings is of particular concern.
Data describing the EPA initial list of high-priority remedial
action sites identifies groundwater contamination in two-thirds of
the cases and surface water contamination in over half of the cases.
The leachate may contain portions of almost every chemical pre-
sent in the hazardous waste. If the original waste contains a liquid
component, it may drain from the waste and -- to the extent that it
has limited water solubility -- create a "second phase" in the
leachate. Such immiscible liquids may, if lighter than water,
spread over the surface of the groundwater table, and, conversely,
may sink to the bottom layers of the aquifer, if heavier than water.
Also, where two phases coexist, the driving force on and resultant
flow of each fluid phase are not always the same. For example, gaso-
line can flow in a different direction from the groundwater over
which it is spread. If the hazardous waste contains a mixture of
both inorganic and organic chemicals, portions of both will be dis-
solved in any percolating water and show up in the leachate. Under
worst case conditions, the amount dissolved may be at the solubility
limit; entrainment of small particles may make the effective concen-
tration even higher. The concentration in groundwater of certain
inorganic species, especially the metals, may be more dependent upon
the soil and leachate chemistry than on the form in the original
waste.
18
-------
FIGURE 2-3
LEACHATE MIGRATION AND GROUNDWATER CONTAMINATION
Surface Disposal
Leachate Runoff
Subsurface Disposal
Above Groundwater Table
Legend:
Hazardous Waste
Leachate
—^t_-_ Groundwater Table
Surface Impoundment
Surface Disposal Partially
Below Groundwater Table
'.' .,-.'. -'-• ..-,. "if r*r -J:
Contaminated Plume
Soil
Direction of Groundwater Flow
19
-------
2.1.1 Containment Techniques
Means to contain leachate migration include:
• reduction of surface infiltration;
• upgradient diversions or barriers;
• downgradient diversions or barriers; and
• leachate and groundwater collection.
The first approach (reduction of surface infiltration) reduces
the potential for leachate production and, thus, migration into the
groundwater. Most leachate is generated by the action of water per-
colating downward through the materials deposited at a disposal
site. Methods for excluding surface water, from a site, discussed
below under Surface Water, also support this approach. This
approach will not eliminate leachate produced by leakage of liquid
components in the waste materials or produced by biodegradation but
may reduce the rate at which they enter the groundwater.
The second means (upgradient diversions or barriers) prevents
groundwater from contacting the waste mass or the leachate plume by
rerouting the groundwater flow pattern and adjusting the level of
the water table. Such techniques are used in the groundwater flow
before it impinges on the site, and hence the term upgradient.
The third approach (downgradient diversions or barriers) is
used to stop and contain the flow of groundwater already contam-
inated by leachate migration or direct contact with the waste.
Groundwater pumping and treatment are typically required with this
approach.
Leachate and groundwater collection, the last approach, com-
prises a number of techniques to intercept the leachate plume or
groundwater stream and move it to a discharge where the contaminated
water can be treated or disposed of under satisfactorily controlled
conditions.
Appropriate remedial actions will vary with the disposal prac-
tice as discussed below. The nature of the remedial action program
will depend on the location of the water table relative to the
wastes. If the preliminary site investigation indicates that the
20
-------
wastes are above the water table, existing weather and hydrogeologi-
cal data should be examined, because the water table fluctuates over
time to determine if the seasonally high water table will intercept
the wastes. In the absence of adequate historical data, the design
should be based on additional tests at the site including soil tests
and determination of color changes in stratigraphic columns.
2.1.1.1 Landfills
Waste Below the Water Table
Water table (or groundwater table) adjustment, plume contain-
ment, and barriers to groundwater flow are potentially applicable
remedial actions for landfills where waste has been placed below the
groundwater table. The primary objective of water table adjustment,
typically accomplished via groundwater extraction (pumped) wells is
to lower the water table below the emplaced wastes. The objective of
plume containment systems, also accomplished by groundwater
extraction wells, is to reverse the downgradient movement of contam-
inated groundwater and collect the contaminated water. Plume
containment systems must also address the treatment and related han-
dling of the contaminated water. The principal objective of
barriers is to control the movement of water either before or after
it contacts the waste.
Water table adjustment by groundwater pumping can reduce the
rate of leachate generation and further, of groundwater contam-
ination. Figure 2-4 schematically illustrates a water table adjust-
ment system. Wells are sited and pumped at rates which will lower
the water table below the emplaced wastes. The specific number and
placement of wells is site specific. Figure 2-4 indicates wells
placed around the perimeter of the site. The wells have lowered the
water table below the waste mass. At some sites it may be feasible
to drill wells directly through the waste although safety consider-
ations, or the potential for further spread of contamination, may
render such an option infeasible or more costly than a periphery
system. Cost-effective well system design (locations, development
techniques, and pumping rates) requires thorough analysis of
site-specific hydrogeologic data and engineering cost data. Water
table adjustment may also be accomplished by subsurface drainage
systems. Selection of a well or drain system is dependent primarily
on the depth of the waste. Drains may be preferred if
construction/emplacement is feasible, and wells where the depth is
greater
21
-------
FIGURE 2-4
WATER TABLE ADJUSTMENT BY EXTRACTION WELLS
Direction of Groundwater Flow
O Extraction Wells
Plan View of Site
Extraction Wells
Water Table
Before Pumping
Water Table
After Pumping
Cross Section AA'
22
-------
Plume containment by groundwater pumping is also potentially
applicable for landfills with waste below the water table. Refer-
ring to Figure 2-4, we see that a pumping system designed for water
table adjustment may also be adequate for plume containment if the
plume of contaminated groundwater has not migrated downgradient
further than the radius of the cone of depression of the dewatering
well. In this case the plume 6f the contaminated groundwater will
flow toward the well and be withdrawn by pumping. This situation is
more likely to occur for newer landfills than for fills which have
accepted hazardous wastes for many years. In general, plume con-
tainment by groundwater pumping would require a well system
independent of the system designed for water table adjustment.
Barriers to groundwater flow (slurry walls, grout curtains,
sheet pile barriers) may also be used to isolate waste from ground-
water at .landfills where wastes are below the water table. The site
specific conditions under which barriers might be useful are poten-
tially so varied that it would be fruitless to try to enumerate and
characterize them in a completely general way. One generic situ-
ation, placing a barrier in a shallow water table aquifer, relates
to a large number of sites with groundwater problems. The following
discussion about that setting serves to illustrate the most impor-
tant features of barrier use. In the more general case, the existing
water table which reflects the water balance and subsurface material
stratigraphy at the site must be considered in estimating the effect
of a barrier.
The principal effect of a groundwater barrier is to reduce sub-
stantially flow perpendicular to the barrier. If the barrier is
very long (in mathematical idealization: an infinite barrier) or
completely crosses the lateral extent of the aquifer and tied to
impermeable strata on all sides, then the groundwater which has been
intercepted by the barrier will accumulate upgradient of the
barrier, causing the water table to rise. This situation is illus-
trated in Figure 2-5. Figure 2-5a shows the natural conditions
with, for example, 10 units of water flowing parallel to the cross
section. Figure 2-5b shows the situation shortly (e.g., weeks)
after the barrier is emplaced. The 10 units of water continue to
flow toward the barrier but practically none gets through.
The steady-state, or long-term response to the barrier emplace-
ment will be completely dependent on localized hydrogeologic fac-
tors, and there is no generic response typical of all such sites.
Figures 2-5c and 2-5d, however, represent steady-state responses
which may be typical of arid and hummid sites, respectively. As the
water table rises upgradient and falls downgradient of the barrier,
small flow through the barrier may occur. The increased head upgra-
23
-------
FIGURE 2-5-a
NATURAL AQUIFER CONDITIONS
FIGURE 2-5-b
[RANSIENT RESPONSE SHORTLY AFTER BARRIER EMPLACEMENT
FIGURE 2-5-c
HYPOTHETICAL STEADY STATE RESPONSE IN AN ARID SETTING
FIGURE 2-5-d
HYPOTHETICAL STEADY STATE RESPONSE IN A HUMID SETTING
Water table
Groundwater flow
24
-------
dient may also force water downward through the relatively
impermeable confining layer below the aquifer.
As the water table rises toward the land surface, evapotranspi-
ration rates will naturally increase. The evaporation rate in arid
climates will often be great enough to balance the natural lateral
flow of water in the aquifer. The water table would equilibrate at
the level (see Figure 2-5c) where the incoming lateral flow (10
units) is blanced by flow through the confining layer (2 units) plus
flow through the barriers (0.1 unit) plus evapotranspiration (7.9
units).
In a more humid climate, evapotranspiration would also increase
as the water table approached the surface, but often not enough to
balance the lateral flow, allowing the water table to eventually
rise to the surface and overtop the barrier (Figure 2-5d) . Clearly,
this would be a poor design, and some additional water control would
be required. For example, groundwater extraction wells upgradient
of the site may be necessary to remove excess groundwater. Although
this is a purely hypothetical situation, many actual situations
where barriers might be used in remedial action will require associ-
ated water controls such as groundwater extraction and recharge
wells, surface water controls, subsurface drains, and so on. Exist-
ing and proposed uses of groundwater barriers in remedial action
typically include associated groundwater controls. For example,
the major slurry wall installation at Rocky Mountain Arsenal,
designed for plume containment, incorporates upgradient extraction
wells, a water treatment system, and subsequent downgradient
injection wells (Wardell, 1981).
The idealized situation characterized by Figure 2-5 is rarely
found in practical applications, because it is usually infeasible to
cutoff the complete lateral extent of an aquifer, or make a barrier
so long that it approaches the response of an ideal infinite
barrier. Less extensive barriers--for example, upgradient of a
waste disposal site—are not likely to be effective in lowering the
water table since they do not prevent water from flowing around the
barrier. Figure 2-6 illustrates this situation. The barrier
diverts groundwater flow around it but will not cause a significant
lowering of the water table downgradient of the barrier. A slight
reduction in head results from viscous energy losses along the long-
er flow path taken by the water after it encounters the barrier. The
resulting head loss immediately downgradient of the barrier will be
proportional to the length of the new flow path, regardless of the
shape of the barrier. This will lead to a flattening of the water
table downgradient but not a substantial dewatering of the waste
site. Although a very long barrier might cause a large enough head
loss to dewater wastes at some sites, a very long barrier is not
25
-------
FIGURE 2-6
EFFECT ON GROUNDWATER LEVEL OF UPGRADIENT BARRIER
Impermeable
Barrier
Waste
Flow
Lines
Plan View
Waste
*y$m\>\immmii
Legend:
——-—-J— Water Table Before Barrier
Water Table After Barrier
Cross Section
26
-------
likely to be less expensive than other dewatering techniques, such
as pumped wells or subsurface drains. Consequently, upgradient bar-
riers which do not intercept the full lateral extent of the aquifer
are not likely to be recommended, alone, for dewatering purposes.
They may be more effective when used in conjunction with surface
water controls or well systems.
An alternative, and generally more effective use of barriers
for dewatering wastes is to completely encircle the waste and tie
into the bedrock (or other impermeable confining beds). Depending
on site-specific hydrogeologic conditions, several configurations
may be effective. If the barrier completely surrounds the waste and
extends to bedrock (or other impermeable layer), lateral groundwa-
ter flow through the waste will be reduced to negligible amounts as
shown in Figure 2-7. In arid climates or at sites with impermeable
surficial material, reduction of lateral flow will eventually dewa-
ter the waste. However, in humid climates with permeable surficial
soils (including permeable waste deposits), vertical infiltration
may lead to a "bathtub" effect, causing high water table within the
barrier which could then increase vertical flow through the waste or
lateral flow through or over the barrier. Capping, pumping, or
leachate collection may be required in conduction with the barrier
to mitigate this "bathtub" effect. Barriers which encircle the
wastes but are not tied to an impermeable layer will reduce, but not
eliminate, leachate contact with the natural groundwater as ground-
water will flow around and under the barrier causing the disposal
site to become a region of "stagnant" groundwater.
If the waste lies below the water table, it will generally be
ineffective to implement controls designed to prevent leachate pro-
duction without including one of the groundwater control measures.
In these cases, lateral migration is often the principal water flow
route through the waste. Thus capping, grading, surface sealing,
surface water diversion, and other measures which may reduce surface
water infiltration are not expected to have significant effect on
groundwater when wastes are below the water table.
Waste Above the Water Table
If wastes are deposited above the water table, groundwater con-
tamination may result from infiltration of surface water downward
through the wastes or by percolation of liquids associated with the
waste downward to the water table. If infiltration of surface water
is generating contaminated leachate, then surface water controls,
such as surface seals, surface water diversions, and grading are
likely to be the most cost-effective measures for reducing further
contamination to groundwater. Subsurface drainage systems may also
27
-------
FIGURE 2-7
EFFECT ON GROUNDWATER LEVEL OF BARRIER SURROUNDING WASTE
Impermeable
Barrier
Plan View
Waste
Flow
Lines
Pump (Optional)-
Impermeable
Barrier
Bedrock
Legend:
—-t—. Water Table before Barrier
—.Ju._ Water Table after Barrier
Cross Section
28
-------
be effective in collecting contaminated leachate before it contam-
inates the subsurface aquifer. However, groundwater controls may
also be necessary to clean up already contaminated portions of the
aquifer.
2.1.1.2 Surface Impoundments
Problems at surface impoundments (often called lagoons or dis-
posal ponds) arise principally from leakage of stored wastes or
leachate through the bottom layers. In the case of unlined surface
impoundments, leakage may occur due to the natural permeability of
the bottom or to a more concentrated leaking area more directly con-
nected to the underlying groundwaters. Remedial action approaches
may be needed at unlined surface impoundments because of their
natural tendency to leak after some period of time.
More recent surface impoundment designs incorporate liners to
prevent leakage. Liners may be synthetic materials or clays of very
low permeability. Even a lined surface impoundment may be a cause of
groundwater contamination if the liner has been damaged either by
chemical interaction with the waste or leachate, physical disturb-
ance or improper design and installation. If a clay liner is leaking
from a few isolated seepage points, it may be possible to repair the
liner, perhaps by grouting. However, the technical feasibility of
liner repair has yet to be generally demonstrated. Currently, it is
very difficult to locate leaks unless a specific physical disturb-
ance has been documented, so in most cases a surface impoundment
with a leaky liner should be dealt with in the same way as an unlined
surface impoundment.
Surface impoundments may be further categorized as being above
or below the water table. If a surface impoundment is above the
water table, leakage will create a mounding of the water table
directly below it as the leachate migrates downward, skewed in the
direction of groundwater flow (see Figure 2-8). Leachate migration
in this situation can be mitigated by lowering the liquid level of
the surface impoundment. Depending on the climate and site condi-
tions, this may be accomplished by several means:
1. diverting incoming runoff;
2. eliminating other sources of water or waste liquids; and
3. pumping liquid out of the surface impoundment.
29
-------
FIGURE 2-8
EFFECT OF LEAKING SURFACE IMPOUNDMENT ON GROUNDWATER CONDITIONS
—¥
Legend:
z_.
V
Water Table before Leakage
Water Table after Leakage
Direction of Flow
After a leaking surface impoundment lying above the water table
has been dewatered, it can then be treated by the
above-the-water-table approaches.
If the base of the leaking surface impoundment is at, near, or
below the water table level, it may not be practical to dewater
(drain) it, as groundwater will tend to seep back in. If this is the
case, then the approach will require the same technologies appropri-
ate for a landfill with wastes below the water table. Water table
adjustment, barriers, or plume containment are likely to be appro-
priate responses.
2.1.1.3 Deep Mine Disposal
Mines have occasionally been used for hazardous waste disposal
30
-------
In Europe, for example, deep, dry salt mines have been used for the
disposal of drummed waste. Such mines can be ideal for disposal of
hazardous waste since, given proper conditions, they isolate the
wastes from potential groundwater contact. Disposal of hazardous
wastes in a salt mine has been proposed at a site in Northeast Ohio.
However, at most mine disposal sites in the United States, effects
of mine disposal on groundwater quality are complex, due to the com-
plicated patterns of water movement through subsurface mines.
Groundwater migrates to the mine walls and then may flow rapidly
through the mine caverns, perhaps subsequently surfacing via seeps
or tunnels, or re-entering the groundwater system. Groundwater bar-
riers may be effective in such an environment, but should not be
instituted without an intensive hydrogeologic and contamination
survey to determine the proper location. Plume containment and
water table adjustment techniques may also be implemented and may be
more cost-effective since they do not require such extensive prelim-
inary investigation.
2.1.1.4 General Site-Specific Considerations
Groundwater contamination problems at hazardous waste disposal
sites may require different types of remedial actions as a result of
other site-specific features besides the waste disposition. The
most appropriate groundwater control program must account for dif-
ferences in geology and the present state of groundwater contam-
ination of the site. A common situation is one in which only a
shallow (upper 8-16 meters, or 25-50 feet) unconfined aquifer is
affected by hazardous waste leachate. This situation lends itself
to essentially the full suite of remedial technologies, although
some specific techniques, such as grouting, are effective under a
limited range of soil conditions. If, on the other hand, the contam-
inated aquifer is artesian (confined), water table adjustment would
not usually be appropriate.
Many sites exhibit a layered sequence of horizontal aquifers,
separated by relatively impermeable horizontal layers of varying
thickness. These layered aquifers are often weakly coupled--in oth-
er words, each aquifer is a separate entity with different flow
rates, water quality, permeability, etc.; but with some water trans-
fer between aquifers at local discontinuities of the intervening
layers (see Figure 2-9). Such conditions are often described as
"leaky" aquifers. Significant modification of the water balance,
permeability, or head in one aquifer as a result of some remedial
action, may affect the "leakage" rates among aquifers. Remedial
actions may be specifically designed to effectuate such change in
inter-aquifer water movement.
31
-------
FIGURE 2-9
LAYERED AQUIFER SYSTEM
-------
Many remedial techniques for groundwater control are not feasi-
ble in deep aquifers. Although slurry trench cutoff wall con-
struction techniques are reported to be capable of placing barriers
up to 125 meters (400 feet) below the surface (Millet and Perez,
1981), 25 meters f80 feet) represents a practical limit at most
sites (D1Appolonia, 1980). Sheet steel barriers cannot be installed
deeper than about 30 meters (93 feet) (EPA, 1978) .
Several of the grouting techniques are effective at great
depth. Subsurface drainage systems are designed for shallow instal-
lation, by excavation or horizontal tunneling. Fortunately,
groundwater contamination by hazardous waste disposal is often, but
not always, limited to near surface aquifers. Contamination of deep
aquifers can usually be "cleaned-up" only by pumping to extract con-
tamination. However, further contamination of a deep aquifer can be
reduced by measures designed to reverse or reduce the flow through
confining beds or through discontinuities (cracks, voids, pipes,
poorly sealed wells or bore holes, fractured rock, etc.) in the con-
fining beds. Appropriate measures include grouting in the vicinity
of discontinuities, or pumping to achieve a general reduction in
driving head of the overlying, contaminated aquifer.
Another site-specific condition which influences the choice of
remedial technique is the site of the existing contaminated zone.
As discussed under the landfill heading, at some sites, water table
adjustment to limit further leachate generation may also provide
plume containment if the contaminated zone is circumscribed by the
cone of depression of extraction wells sited for water table adjust-
ment. In other cases a plume containment well must be sited far
downgradient of the disposal site to reverse the flow at the leading
edge of the contaminated plume. Access to appropriate locations for
such plume containment wells may not be feasible for a variety of
reasons.
The cost of plume control remedial measures is usually propor-
tional to the size of the contaminated zone. Alternatively, source
control cost is proportional to the size of the waste disposal site.
Thus, the selection of remedial technique may be influenced by the
relative area or volume of contaminated groundwater compared to the
area or volume of the waste site. This ratio tends to be larger for
older sites than younger ones. For example, at older sites an upgra-
dient barrier, or water table adjustment system that limits further
leachate generation, is more likely to rate higher in
cost-effectiveness relative to downgradient controls or plume con-
tainment measures, than at a younger site where the leading edge of
contaminated groundwater has not progressed far from the site.
33
-------
The chemical characteristics of the waste and leachate will be a
significant factor in the selection of leachate controls. For exam-
ple:
• sheet metal barriers should not be used if exposed to corro-
sive leachate;
• curtain grouts are subject to degradation by specific types
of leachate; and
• it is unsafe to drill through highly volatile or explosive
wastes.
2.1.2 Treatment Technologies
An alternative or conjunctive approach to groundwater or leach-
ate control and containment is treatment to eliminate or mitigate
the hazard-producing characteristics of the contaminated groundwa-
ter or leachate. The original source of hazards, the waste or con-
taminated soil in and around the site, could be treated; techniques
for this approach are discussed in a later section. Alternatively,
the contaminated groundwater or leachate could be brought to the
surface and treated to decontaminate and/or concentrate the hazard-
ous components. In situ treatment is also possible and is discussed
in the subsection on contaminated soils and waste materials. The
technologies described in this subsection are applicable to contam-
inated fluid extracted or pumped to the surface. Applicable
treatment technologies can be grouped into the following
categories:
• biological;
• chemical; and
• physical.
Biological treatment processes are applicable to a wide range
of organic compounds; chemical and physical methods are generally
applicable to both inorganic and organic compounds. Generally,
treatment processes produce an aqueous effluent in which the levels
of hazardous constituents have been significantly reduced and a
sludge or liquid residual in which the hazardous materials or pro-
cess by-products are concentrated .The aqueous effluent may then be
discharged to surface water, groundwater, or a municipal sewage
treatment plant. Acceptable water quality standards; i.e., BOD, pH,
priority pollutant levels, for the effluent will be dependent on the
34
-------
receiving stream and determined on a case-by-case basis. Treatment
process residuals are generally hazardous materials and should be
disposed or treated as such.
To select a treatment process, contaminated groundwater or
leachate must be characterized and appropriate technologies tested
on the laboratory scale. Contaminated groundwater or leachate from
uncontrolled sites typically contains a complex mixture of many con-
taminants, all of which usually cannot be successfully treated by
any one technology. Therefore, several technologies are generally
employed. The selection of the technologies and the order of appli-
cation, usually called the process train, are the key factors for
cost-effective treatment (TRD 5). The most practical technologies
in each treatment category and selection of a process train are dis-
cussed in the following subsections. A more extensive list of
treatment technologies is discussed in detail in Section 3.
2.1.2.1 Biological Treatment
Biological treatment processes are applicable to a large number
of organic wastes. Activated sludge processes are probably the most
applicable to groundwater or leachate treatment. This process
involves the oxidation or hydrolysis of organic compounds in an aer-
ated reaction tank by a biomass acclimated to the influent waste
stream. The treated waste stream passes through a clarifier where
the activated sludge settles. A portion of the sludge is recycled to
the aeration tank and the remainder removed for disposal. The
effluent from the clarifier is discharged. The micro-organisms in
the activated sludge can acclimate to a wide variety of waste
streams. Specific micro-organisms can be isolated and utilized to
seed sludges for the destruction of organic compounds. Activated
sludge treatment, however, is not capable of destroying refractory
compounds such as PCBs and polynuclear aromatic compounds. Some
organic species and metals are toxic to activated sludge bacteria
and must be removed prior to treatment. Volatile organics present
in the influent may be stripped from the aqueous phase by aeration,
producing undesired atmospheric emissions.
Other biological processes which may be applicable include:
• aerated surface impoundments;
• land treatment;
• anaerobic digestion; and
35
-------
• trickling filters.
Aerated lagoons are similar to, but simpler than, activated
sludge operation. No sludge is recycled resulting in reduced
biomass acclimation and lower treatment efficiency. However, if
leachate residence time in an aerated lagoon is of similar order to
the sludge residence time in an activated sludge system, similar
treatment efficiencies are expected. Land treatment is the applica-
tion of contaminated groundwater or leachate to soils where aerobic
degradation occurs as the fluid contacts soils containing natural or
seeded bacteria. Often treatment includes a recycling system to
collect the percolated fluid and reapply it to the surface soil.
Anaerobic digestion is the microbial degradation of organic
compounds in a reactor in the absence of air. It is used primarily
to treat carbohydrates, lipids, protein, alcohols and organic acids
(ADL, 1977). It is inhibited by oils, fats, greases, and soluble
metals. Trickling filters are structures containing an open support
medium covered with a coating of microbial slime. The
biologically-active coating reacts with the organic compounds in
the contaminated groundwater or leachate which trickles down
through the structure.
2.1.2.2 Chemical Treatment
Chemical precipitation is a conventional process for removing
soluble metals from contaminated groundwater or leachate. Chemi-
cals are added to form insoluble forms of the unwanted species.
Often only the pH is adjusted to form insoluble metal hydroxides and
carbonates. In cases where metal concentrations lower than can be
obtained by precipitation of the hydroxides must be achieved, a sul-
fide chemical; i.e., sodium sulfide, is added to form insoluble
metal sulfides. The insoluble metal salts are separated from the
aqueous phase by gravitational settling. To promote settling, floc-
culating agents which act to conglomerate smaller insoluble
particles into larger ones are added.
Some contaminants such as cyanide, ammonia, amines, etc.,
reduce the effectiveness of chemical precipitation by forming sta-
ble, soluble metal complexes. If these interfering contaminants are
present, pretreatment to destroy or remove the complexing agent may
be necessary.
Chemical oxidation and reduction are methods which alter the
valence state of a waste constituent. Two primary applications are
36
-------
the oxidation of cyanide to carbon dioxide and nitrogen; and
reduction of hexavalent chromium to the less-toxic trivalent form.
Organics such as phenols, alcohols, and pesticides can also be oxi-
dized. Ozone, hydrogen peroxide and chlorine are the major oxidiz-
ing agents used to "treat waste. Chlorine can react with ammonia,
amines, and many organics to form chlorinated reaction products
which may, in themselves, be hazardous. Chlorine should be used
only when tests prove its safety. In contrast to chlorine, ozone and
hydrogen peroxide do not react with .wastes to form any generic
classes of hazardous compounds and can be used broadly. These lat-
ter two oxidants are often used in conjunction with biological
and/or carbon adsorption processes to 'treat a diverse range of
organic wastes. Ozonation coupled with ultraviolet irradiation has
demonstrated potential as a primary treatment process for organics.
Ion exchange is a method to remove inorganic salts from an aque-
ous solution by typically exchanging a hydrogen ion for a cation or a
hydroxide group for an anion. The method is expensive compared to
chemical precipitation and usually employed only as a polishing
step; i.e., to remove very small quantities of contaminants remain-
ing after the principal treatment step.
Chemical neutralization is the adjustment of pH by adding a
chemical agent, such as lime or sulfuric acid, to raise or lower the
pH respectively. For discharge to a municipal sewage treatment
plant a pH range of 6.0 to 9.5 is generally considered acceptable.
Wet air oxidation process involves the mixing of air and aqueous
waste at high temperature and pressure to oxidize the waste. The
method is capable of oxidizing refractory organics and should be
considered for contaminated groundwater or leachate with concen-
trations of organics too high for biological treatment or too dilute
for cost-effective incineration. Potential applications include
oxidation of concentrated- streams generated by other treatment
methods such as reverse osmosis and ultrafiltration.
2.1.2.3 Physical Treatment
Activated carbon adsorption primarily removes organic contam-
inants from an aqueous waste stream. The contaminants are bound to
the carbon by physical and/or chemical forces. Activated carbon is
available in two forms, powdered and granular. The granular form is
the most commonly used. Granular carbon can be thermally regener-
ated; the contaminants are generally destroyed in the process. Pow-
dered carbon is less expensive but not easily regenerated and may be
difficult to separate out of the waste stream.
37
-------
Carbon adsorption is well suited for contaminated groundwater
or leachate treatment because it is capable of removing complex mix-
tures of organic contaminants including refractory organics from
aqueous waste. The process can be utilized for complete treatment
for organic contamination or in conjunction with biological pro-
cesses to remove refractory organics or organic constituents toxic
to the biological process.
Resin adsorption is similar to activated carbon adsorption.
The process is applicable to a wide range of organic contaminants.
However, the high cost of resin makes the process economically
uncompetitive with activated carbon adsorption except for low vol-
ume, specialized applications.
Density separation involves either the sedimentation of settle-
able material or the flotation of solids and/or light hydrocarbons
to the surface of a liquid phase. Sedimentation is a well
understood, low-cost process that typically follows chemical pre-
cipitation and activated sludge biological treatment. Flotation
processes typically introduce air bubbles into an aqueous system
which attach to the solid phase. The unwanted solids are then col-
lected as they rise to the surface. The process is well suited for
waste streams with high loads of grease.
Filtration processes remove suspended solids from a solution by
forcing the liqid phase through a porous media and retaining the
solid phase within or on the surface of the filter medium. Filter
media include sand, diatomaceous earth, filter cloths and filter
screens. Filtering processes are generally pre- or post-treatment
steps to remove solids which interfere with a treatment process or
to reduce suspended solid loads of an effluent after chemical pre-
cipitation and sedimentation. The processes are well understood and
usually low in cost.
Reverse osmosis concentrates inorganic salts and some organic
species; (i.e., species with molecular weights greater than 300
grams/mole), by applying pressure to force the solvent phase through
a membrane which is impermeable to the inorganic salt and some
organic constituents. Reverse osmosis operating efficiency is very
sensitive to feed stream composition, limiting applications gener-
ally to post-treatment of effluent or a pretreatment concentration
step for wet air oxidation.
Air and steam stripping are the two major stripping technolo-
gies. Air stripping involves the introduction of airflow through an
aqueous system to facilitate the release of volatile constituents.
38
-------
Air stripping is primarily utilized to remove ammonia from wastewa-
ters. Steam stripping is essentially a distillation of volatile
organic compounds. Air pollution problems must be considered if
these technologies are applied.
2.1.2.4 Process Train Selection
To remove complex mixtures of contaminants from leachate or
groundwater adequately it is usually necessary to apply several
treatment technologies. Applicable technologies for treating
generic classes of leachate contaminants are listed in Table 2-1.
This list includes technologies considered best suited for leachate
treatment, in general, and is not intended to be a comprehensive
list. The selection of appropriate technologies and application
sequences is a key factor to accomplish cost-effective treatment.
Contaminated groundwater or leachate samples must be characterized
to determine what treatment is necessary and which unit processes
are applicable. Treatment schemes should be tested on a laboratory
and/or pilot scale prior to field implementation. Based on test
results, an effective treatment process train can be designed.
2.2 SURFACE WATER
Water is the primary means by which hazardous materials can be
transported from an uncontrolled disposal site to the surrounding
environment. Pollutants can either be dissolved or suspended in
water and carried to groundwater, surface waters, or off-site land
surfaces. Water control and treatment is therefore of primary
importance in remedial action at uncontrolled hazardous waste sites
(TRD 8). Groundwater control, containment and collection technolo-
gies, as discussed in the previous section, are designed to prevent
leachate from contaminating groundwater, and, if unavoidable or
having occurred, to prevent the contaminated groundwater from con-
taminating aquifers and surface supplies downgradient from the
waste site. Similarly, surface water control, containment and col-
lection technologies are designed to prevent surface waters from
becoming contaminated through contact with waste or contaminated
soils and, if that occurs, to prevent further contamination offsite
(TRD 9). Surface water technologies fall into three major catego-
ries :
1. water exclusion measures that are designed to p revent the
infiltration of water to the wastes, thereby min mizing the
production of leachate;
39
-------
TABLE 2-1
APPLICABILITY OF UNIT PROCESSES TO LEACHATE
OR GROUNDWATER CONTAMINANTS
Waste Type
Acids, Bases, Inorganics
Metals
Applicable
Processes
• Neutralization
• Chemical Oxidation
• Chemical Reduction
• Stripping
• Ion Exchange
• Reverse Osmosis
• Chemical Precipitation
• Ion Exchange
• Reverse Osmosis
Waste Type
Organics
Suspended Solids
Applicable
Processes
• Biological Treatment
• Carbon Adsorption
• Resin Adsorption
• Chemical Oxidation
• Stripping
• Reverse Osmosis
• Sedimentation
• Flotation
• Filtration
Source: TRD 5
water collection measures that are designed to prevent sur-
face water containing hazardous waste leachate from contam-
inating off-site soil and water resources; and
erosion control measures.
The next sub-section discusses the important general character-
istics of sites that determine the applicability and design of these
measures. Discussion of technical approaches follows that dis-
cussion.
40
-------
2.2.1 General Characteristics
water collection and exclusion technologies should be designed
to handle the maximum quantities of water expected (from preliminary
analysis) with a margin of safety. This is especially true of a
water collection system since its failure would mean the release of
potentially hazardous leachate. Maximum quantities of runoff can be
expected during and after an intense storm, depending on the hydro-
logic conditions of the site. In mountainous areas spring thaw can
cause a peak runoff due to rain and snowmelt. Coastal and riverine
flooding can also be a problem in certain areas. The hydrologic
analysis should indicate the maximum flow of water which can be
expected. Surface water controls should be designed to at least
withstand a 24-hour, 25-year rainfall (TRD 8). More stringent
design may be necessary in certain areas where flooding is consid-
ered likely or where site hazards are considered particularly acute.
2.2.1.1 Water Exclusion Measures
Water exclusion measures are designed to prevent water from
getting in contact with the waste. This can be done in two ways:
• prevent runon from off-site sources; and
• prevent infiltration through the site surface.
Runon can be defined as any water originating off-site which
flows across the surface of an uncontrolled hazardous waste site.
It includes stormwater, floodwater and snowmelt. Diverting this
water around or away from the waste site greatly reduces the quanti-
ty of water flowing across a waste site and therefore reduces the
potential for infiltration and contamination of off-site areas via
contaminated runoff. If all water from off site is successfully
diverted around or away from the site, then the only manner in which
water can reach the site surface is through direct precipitation or
groundwater discharge.
Control methods function by modifying the water balance at a
site. Proper control can minimize the production of leachate and
limit the flow of leachate to the surface water collection system.
The water balance for surface water can be modeled by the following
equation:
41
-------
P-E-T = R + I + AS
Where:
P = direct precipitation
E = evaporation
T = transpiration
R = runoff
I = infiltration
AS = change in storage
It is important to understand which of these terms are most
important at a given site. This will depend on site-specific and
regional characteristics as well as the nature of the precipitation
event. Site investigation should include a hydrologic study to ana-
lyze the effect of these factors on the terms in the water balance.
TRD 2 describes the water balance in detail and provides an interac-
tive, user-friendly computer program for quantifying the water
balance parameters at a solid waste disposal site.
For precipitation falling on site, the objective of water
exclusion measures is to prevent leachate generation by eliminating
infiltration. Since precipitation cannot be controlled at a site,
the water balance shows that this must be accomplished by increasing
the other terms in the equation. On-site water exclusion measures
are therefore designed to maximize the quantities of water that run
off or are otherwise transferred off site. Some methods are also
designed to increase potential surface storage by accelerating the
removal of water through evaporation and transpiration.
2.2.1.2 Water Collection and Transfer Measures
Surface water collection measures are designed to prevent sur-
face water leachate from contaminating off-site areas. They are
used in conjunction with water exclusion measures. Water exclusion
measures are primarily concerned with the quantity of water that
infiltrates at the site. Water collection measures, on the other
hand, are concerned with the quantity and quality of water moving
off site. Five options exist for dealing with water that has run off
or is transferred off-site (TRD 5) :
42
-------
1. route uncontaminated flow, from on-site or off-site diver-
sions, directly to surface water courses or to a holding or
storage pond for more controlled discharges;
2. route mildly contaminated flow to holding or storage area
and treat prior to discharge;
3. route contaminated runoff to on-site leachate treatment
plant;
4. place contaminated runoff back into the disposal area; and
5. ship contaminated runoff off site for appropriate treatment
and disposal.
Runoff quality is a function of waste characteristics (for
example, solubility, pH, percent liquid), and the type of inter-
action occurring between water and waste (for example, time of con-
tact, mixing, scouring).
2.2.1.3 Erosion Control
Surface water measures are concerned not only with the pre-
vention of infiltration and off-site movement of contaminants, but
also with erosion control. Erosion of soil can cause buried wastes
to be exposed and transported with contaminated soil off site, and
sediments can accumulate in storage basins, limiting their effec-
tiveness. Erosion can also damage remedial action technologies if
runoff flow velocities and volumes are not carefully controlled (TRD
11). This complicates the relationship between terms in the water
balance. Technologies for increasing runoff from the site, for
example, must be designed not only to maximize the amount of water
running off, but also to keep overland flow velocities below the
erosive limit and to prevent channelization (TRD 8) .
2.2.2 Surface Water Control Technologies
There are a number of technologies which can be used for the
control, containment or collection of surface water. Water exclu-
sion measures include barriers and landscaping techniques. Water
collection measures include routing and discharge technologies.
These technologies, summarized in Table 2-2, are designed to perform
six basic functions:
1. prevent runon;
43
-------
TABLE 2-2
SURFACE WATER TECHNOLOGIES
Minimize
Technology Runon
Flood control dikes
Runoff control dikes X
Terraces X
Channels
Chutes
Downpipes
Grading X
Surface seals
Vegetation X
Seepage basins
Seepage ditches
Primary Function
Minimize Reduce Protection from Collect and Discharge
Infiltration Erosion Flooding Transfer Water Water
X
X
X
x x
x x
x x
X
X
X X
X
X
-------
2. control infiltration;
3. prevent erosion;
4. collect and" transfer water;
5. store and discharge water; and
6. protect against flooding.
Some technologies perform more than one of these functions.
Other technologies may require backup or complementary technologies
or may only have limited application at a given site. A surface
water management system, therefore, may require a combination of
technologies to minimize the production of leachate and prevent
off-site contamination adequately.
2.2.2.1 Prevention of Runon
Technologies which are designed to prevent or reduce runon
include: dikes, diversion channels, floodwalls, terraces, grading
and revegetation. Temporary diversion dikes, diversion channels
and terraces are diversion measures constructed upslope of a site to
direct runon from off site to a collection system or away from the
site. Terraces are used in combination with dikes or ditches to
channel water stopped by the terraces away from the site. Flood con-
trol dikes (or embankments) and floodwalls are flood protection
measures constructed as perimeter structures surrounding a waste
site to isolate the site from floodwaters. Embankments in areas
subject to river flooding are called levees. They are more expen-
sive than runoff dikes or terraces and will usually be used only in
areas where flooding is likely to be a problem. Floodwalls, which
are more expensive than levees, can be used at sites with insuffi-
cient land area to construct a levee. Grading and revegetation,
which are primarily for erosion control, reduce quantities of water
available for runon by increasing off-site infiltration and inter-
ception. They are used in conjunction with the other technologies
mentioned above to increase their effectiveness.
2.2.2.2 Prevention of Infiltration
The primary method for preventing the infiltration of on-site
surface water is surface sealing. This involves placing a cap or
cover of low permeability over portions of the site where infil-
tration needs to be eliminated. Surface seals should be graded so
that the maximum amount of water will run off without causing sig-
45
-------
nificant erosion. Revegetation of the cover will reduce erosion but
might also increase infiltration. The roots of the vegetation pro-
vide a pathway for infiltration through the surface layers and may
penetrate the barrier layer. However, with proper selection and
management of the vegetation cover, much of the infiltrating water
can be taken up by the root system. This amount will depend on the
quantity of precipitation and runoff, as well as other climatic con-
ditions. A surface seal must therefore be carefully designed to
satisfactorily reduce infiltration and maintain stability through-
out the desired lifetime.
2.2.2.3 Erosion Control
Erosion can be modeled by the Universal Soil Loss Equation (TRD
1) . The equation is:
A = RKLSCP
Where:
A = average soil loss, in tons/acre/year
R = rainfall and runoff erosivity index
K = soil erodibility factor
L = slope length factor
S = slope steepness factor
C = cover/management factor
P = practice factor
Erosion potential is, therefore, a function of the inherent
erodibility of the soil (K) as well as many other factors. The soil
erodibility factor can be determined using a nomograph and depends
on soil structure, texture, and permeability. Soil erodibility is
also often expressed in qualitative terms (high, moderate, low or
erosive, resistant). Methods for determining values for the factors
in the equation can be found in TRD 8.
Surface water control technologies reduce erosion by reducing
slope length (L), slope steepness (S), or improving soil management
(C). Dikes, diversion channels, and terraces can be used to reduce
slope length. Dikes used for this purpose are called interceptor
dikes. They differ from diversion dikes primarily in their design
46
-------
specifications. Slope steepness is reduced by grading. Proper
grading allows water to run off without forming channels or attain-
ing sufficient velocity to cause significant erosion. Choice of
vegetation is crucial and will depend on soil fertility, climate,
hydrologic condition, and desired function. Revegetation should be
considered in increasing the stability of all earthen surface water
control measures.
2.2.2.4 Collection and Transfer of Water
Collection and transfer technologies include waterways, chutes
and downpipes. They serve to collect water which has been diverted
away from the site or prevented from infiltrating, and transfer it
either to direct discharge or storage for treatment or more con-
trolled discharge. Chutes (or flumes) and downpipes (or drainpipes)
are designed to transfer water away from diversion structures such
as dikes or terraces to stabilized channels or outlets. Waterways
can be used to intercept or divert water as well as collect and
transfer water diverted elsewhere. They are the stabilized channels
that form the base of the surface water collection system. They col-
lect water from diversion structures, chutes, downpipes and ditches
and channel it either to treatment or discharge.
2.2.2.5 Storage and Discharge of Water
Water storage and discharge technologies include seepage basins
and ditches, sedimentation basins, and storage ponds. Their func-
tion will depend on the level of contamination of the water they
receive. Seepage basins and ditches are used to discharge uncontam-
inated or treated water downgradient of the site. Sedimentation
basins are used to control suspended solid particles in surface
water flow. They can be part of the water treatment process and
their design will depend on that process and the amount of solids in
the surface water. Finally, storage ponds are used to store col-
lected surface and groundwater when flow rates are in excess of
treatment or discharge capacities. Sedimentation basins and stor-
age ponds are not discussed in Section 3. Further information can be
found in Erosion and Sediment Control (EPA, 1976, Vol. I and II).
2.3 CONTAMINATED SOIL AND WASTE MATERIALS
Waste materials and contaminated soil are the basic source of
problems at uncontrolled sites. Surface waters may become contam-
inated with run off that has contacted waste and/or contaminated
soils, and groundwater may be threatened by leachate from or direct
47
-------
contact with the waste and contaminated soil. Air emissions result
from the volatilization of waste materials or entrainment of waste
and/or contaminated soils. Containment measures such as slurry
walls, covers, leachate collection systems, etc., can effectively
isolate waste, but may require long-term care. Failure of contain-
ment systems may result in renewal of the original environmental
hazards at the site and surrounding area. In contrast, removal or
on-site detoxification of waste and contaminated soils offer a
long-term solution and may render the site suitable for alternative
uses. Removal of all contamination, however, maybe very costly and
application of on-site detoxification methods may be limited by the
complexity of wastes in uncontrolled sites.
Waste materials include:
• landfilled sludges, solids and drummed materials;
• surface impoundment liquids and sludge bottoms;
• drummed waste stored above ground; and
• land treatment soil layers.
Soils become contaminated by seepage from or mixing with wastes
or leachate from waste. Therefore, soil contamination may extend
beyond the area of waste disposal activities.
Landfilled waste and soils may be mobilized by water percolat-
ing through the site, surface runoff, volatilization, and air
entrainment of particulates. Drummed materials disposed of in land-
fills present a special set of problems. Incompatible waste iso-
lated by containment in drums may be disposed of side by side in a
landfill. If the drums corrode and leak, the waste could mix and
react violently. An uncontrolled landfill site in Coventry, Rhode
Island was recognized when drums containing water-sensitive materi-
als corroded and were exposed to water resulting in explosions.
Such occurrences endanger the safety of personnel present at the
site and could possibly damage other remedial containment measures
resulting in costly repair actions.
Typically, stored waste is contained in 55-gallon drums which
can corrode and leak. Potential problems include:
• soil contamination;
48
-------
• other waste contamination;
• surface water contamination;
• groundwater contamination;
• air emissions/odors; and
• fire.
If large quantities of reactive and flammable waste are
present, a fire could generate a plume of toxic gases, potentially
dangerous to the population downwind. Analyses of smoke from the
April 21, 1981 fire at the Chemical Control Corporation in
Elizabeth, New Jersey indicated the presence of benzene at a level
of 10,000 ppm (Finkel and Golob, 1981) a level 1,000 times the OSHA
eight-hour time-weighted average concentration standard for
benzene. Other problems that could be caused by fire are contam-
ination of large volumes of debris and soil on site, and of the water
used to control the fire.
Major factors affecting the choice of removal versus contain-
ment or combination of options are:
• transport distance to treatment and disposal facilities;
• quantity of waste and soils;
• need to implement other remedial actions independent of
removal;
• nature of hazard posed by the abandoned site;
• treatability of wastes and soils; and
• cost.
The technologies applicable to removal and detoxification tech-
nologies are discussed in general terms below. Each of the technol-
ogies is discussed in more detail in Section 3.
Four types of response actions to waste and contaminated soils
are:
removal;
49
-------
• on-site treatment;
• in situ treatment; and
• on-site secure disposal.
Removal methods transfer the wastes to off-site treatment
and/or disposal facilities. On-site treatment decontaminates the
wastes and soils at a facility located on or adjacent to the site.
In situ treatment methods decontaminate the wastes in place.
On-site secure disposal involves, in effect, building a secure land-
fill on part of the site for the contaminated materials. It may
involve rearranging the wastes to clear an area for reconstruction.
This approach will not be discussed further in this report. For fur-
ther information on controlled disposal facilities, please refer
directly to the TRDs. The eleven currently available TRDs are sum-
marized in Section 1. In particular TRD 1 discusses covers, TRD 4
discusses liners,and TRD 8 discusses closure and post-closure plan-
ning.
A combination of these approaches may be applied at a site. For
instance, a sludge could be excavated, dewatered on site, and the
residual transported to a secure landfill. An overview of technolo-
gies applicable to each approach is presented below.
2.3.1 Removal
Excavation of landfilled waste is the major removal technology.
Either a backhoe or a dragline crane is commonly employed. Backhoes
are available to reach depths up to 21 meters (70 feet)(ASCE, 1982).
Draglines are available to reach depths of nearly 18 meters (60
feet)(EPA, 1982). The backhoe is usually the more versatile piece
of equipment in that it is more maneuverable, and can be convenient-
ly used to backfill the excavation (Grim and Hill, 1974). Although
excavation at construction sites is a well-demonstrated technology,
the application to hazardous waste sites presents some unique prob-
lems. The load-bearing capacity and fill density which may be
affected by the buried waste should be considered before deciding to
operate heavy equipment at the site. Landfilled drums must be han-
dled with caution. If drums are punctured or already leaking,
additional soil at the site can be contaminated. Sparks created by
drum contact with grappling hooks can ignite flammable or explosive
waste. Typically, drums are moved to a staging area for transfer or
to a secure drum or a tank truck.
50
-------
Operations at a site may be hazardous and special precautions
should be taken. Operators of equipment may be exposed to hazardous
vapors and to direct contact with liquids, solids, and contaminated
surfaces. Protective clothing, including respirators may be
required in some cases. Equipment may become contaminated and
require decontamination before it can be taken off site and used
somewhere else. Dust raised by activities at the site may be contam-
inated with hazardous materials and should be minimized through
application of proper dust suppression techniques.
Surface impoundment sludge bottoms and contaminated soils can
be removed by dredging techniques such as centrifugal pumping and
hydraulic pipeline dredges. «£oth methods are readily available and
comparable in cost. The waste can be pumped directly to tank trucks
as a low-solid content sludge (less than 20 percent solids). If
transport distances to a dewatering facility are large, it may be
cost-effective to dewater on site. Impoundments can be drained pri-
or to sludge removal by pumping the liquid phase to a tank or other
receptor. The uncovered sludge could present an odor problem.
Dried sludges can be removed with the backhoe or dragline equipment
discussed previously.
Several approaches are available for handling drummed wastes.
Drums in good condition can simply be loaded onto a truck and trans-
ported to an off-site treatment, storage, or disposal (TSD)
facility. The contents of corroded drums can be transferred to
secure drums or mixed with a solidification material such as kiln
dust, for off-site disposal. A third alternative is to blend the
contents of drummed waste in holding tanks and subsequently pump the
blended materials into a tank truck for removal. Blending oper-
ations must be carefully monitored; extensive preblending and
sampling of drums is necessary to screen for incompatible waste.
2.3.2 On-site Treatment
Approaches to on-site treatment of soils and waste include:
• physical/chemical/biological treatment;
• solidification/ stabilization; and
• incineration.
Physical/chemical/biological treatment methods either detoxify
waste or separate and/or concentrate a waste.
-------
Solidification/stabilization technologies incorporate waste in a
solid form that reduces leachate generation potential and renders
the waste more suitable for landfilling or long-term storage. Incin-
eration thermally decomposes organic hydrocarbons waste principally
to carbon dioxide and water. Other gaseous species and a solid resi-
due may also be produced depending on the waste composition.
Inorganic constituents, after incineration, yield solid oxides and
acids predominantly.
2.3.2.1 Physical/Chemical/Biological Treatment
There are many individual unit processes for
physical/chemical/biological treatment of waste materials and con-
taminated soil, including, for example, the following twenty pro-
cesses (TRD 5) :
• biological treatment • evaporation
• carbon adsorption • filtration
• catalysis • floculation
• chemical oxidation • ion exchange
• chemical reduction • resin adsorption
• chemical precipitation • reverse osmosis
• crystallization • solvent extraction
• density separation • stripping
• dialysis/electrodialysis • ultrafiltration
• distillation • wet oxidation
Each unit process is applicable to only certain waste streams.
For example, carbon adsorption is a good method for removing chlori-
nated organics, but not metals, from an aqueous solution. A more
detailed discussion of the applicability of each technology will be
presented in the next section.
A single unit process may be applicable to homogeneous drummed
waste at a site or a surface impoundment which has received a homoge-
nous waste stream. However, wastes at abandoned sites are typically
complex mixtures. Impoundments and barrels may contain wastes from
several process streams and drummed waste from numerous sources can
cover a wide spectrum of waste types. One component of a waste may
interfere with the treatment of another by a single unit process. It
is usually necessary to combine several of the above unit processes
52
-------
to treat waste mixtures. The process sequence is dependent on the
technology used for each treatment category. For example, the pro-
cess sequence for treating an aqueous mixture of metal salts and
chlorinated solvents could be either of the two shown in Figure
2-10. To select the proper unit process(es) and treatment sequence,
extensive lab testing should be conducted. An extensive discussion
of treatment train selection can be found in TRD 5.
2.3.2.2 Solidification/Stabilization
Solidification/stabilization technologies include (TRD 6) :
• cementation, using Portland cement;
• pozzolanic cementation;
• thermoplastic binding;
• organic polymer binding;
• surface encapsulation; and
• glassification.
These technologies are applicable, in general, to diverse types
of inorganic waste materials, but not, in most cases, where greater
than 10 to 20 percent organic materials are present. Important
waste characteristics that impact solidification/stabilization
technologies include: pH, buffer capacity, water content, and spe-
cific inorganic constituents (TRD 6) .
Of the methods listed, cementation and pozzolanic reactions are
generally the most widely applicable to wastes over a wide range of
composition. In the two cementation techniques, Portland cement or
lime and a pozzolanic material; i.e., fly ash or cement kiln dust,
respectively, are mixed with a slurry of the waste stream. After the
slurried mix has set up, the volume is typically twice the initial
waste volume. The cemented product has permeability on the order of
10~5to 10~7cm/sec., high structural integrity, and improved resist-
ance to leaching. Inorganic constituents in the waste, however, may
cause large changes in the physical and chemical properties of the
cemented product.
Thermoplastic binding (for example, with asphaltic bitumens) is
suitable for inorganic waste with little or no organic materials
53
-------
FIGURE 2-10
ALTERNATIVE TREATMENT SEQUENCES FOR AN AQUEOUS MIXTURE OF METALS
AND CHLORINATED DECREASING SOLVENTS
Alternative #1
Waste
Waste _
Chemical
Precipitation
\
Metal
Sludge
r
Filtration
i
»^
Fil
i
f
Ex
Solids
r i
Carbon Effluent
^ Adsorption ••"
Solids
l
Alternative #2
Residual
Spent
' . + Waste
Carbon _
Constituents
'
on Carbon Effluent
change ^ Adsorption
Metal
Contaminated
Resins
1
Residual
Spent
„ . + Waste
Carbon _
Constituents
-
-------
present. Thermoplastic binding is more expensive than cementation.
The thermoplastics are sensitive to attack by many organic constitu-
ents .
Encapsulation is a related technique in which waste in contain-
ers or waste bound up in a cement, polymer, or thermoplastic matrix
is enclosed in a stable, water resistant covering. This method, now
in the developmental stage, may be very useful in relocating drummed
wastes at the inactive site.
2.3.2.3 Incineration
Incineration is a proven organic waste destruction technology.
extensive discussion of incinerator technology and its relevance
to waste treatment can be found in the "Engineering Handbook for
Hazardous Waste Incinerators" (EPA, 1981). *A rotary kiln incinera-
tor will be, generally, the best form of equipment for mixed wastes
containing solid residues found at abandoned or uncontrolled sites.
Incineration is often more expensive than other treatment technolo-
gies, but offers effective destruction of organic waste including
refractory compounds, such as PCBs. The incinerator should include
a pollution control device, such as a scrubber, where emissions are
likely to cause an air pollution problem (e.g., with acidic emis-
sions). The wastes can be incinerated on site or off site at an
existing facility. On-site incineration may be the preferable
treatment method for highly toxic, organic waste, particularly if
there are large volumes of contaminated waste that are expensive to
transport. Mobile incinerator systems have been marketed by commer-
cial firms. One such system uses molten iron or molten salt in its
primary chamber and is reported to achieve 99.9999 percent
destruction efficiency for PCB materials (Chemical Engineering,
1981). Incineration of explosive compounds, while not currently
proven, may be possible in the near future.
2.3.3 In Situ Methods
In situ methods treat the wastes in place and are similar to the
on-site treatment techniques discussed above, except that the
wastes are left in place and the process takes place within the waste
mass. Application of in situ methods could eliminate or reduce the
need for expensive excavations or decontaminated actions. Poten-
tial technologies include:
• biological;
55
-------
• physical/chemical detoxification;
• vitrification; and
• solution mining (extraction).
One biological approach is land treatment at a site containing
surface soil contaminated with organic waste from leaking barrels
that have been removed. Aeration of the soil together with control
of surface water infiltration and runoff, will promote the activity
of soil organisms and, thus, reduce the residual toxicity. Inocu-
lation of active species can be used to promote the activity of the
indigenous species. Biological treatment is limited to organic con-
stituents; the other methods are applicable to a wider range of
waste.
Physical/chemical methods introduce a reactant into the wastes
to detoxify the hazardous components by chemical reaction or by
adsorption on a substrate such as activated carbon. Oxidation of
cyanide wastes with sodium hypochlorite has been used at an inactive
cyanide salt disposal pit in the Midwest. Other variations of the
class of methods include reduction of hexavalent chromium with fer-
rous sulfate and the precipitation of a wide range of heavy metals by
pH adjustment and sulfide addition.
Generally, a waste must be fairly homogenous to apply in situ
physical/chemical methods. Physical/chemical in situ methods pose
the risk of generating or volatilizing other toxic constituents by
action of the added reagents; it is important to characterize the
wastes thoroughly before using this approach.
In in situ vitrification, the waste is fused into a glassy, sta-
ble matrix by heating it in place. One such method now under devel-
opment, passes an electrical current through the wastes to produce
high temperature and subsequent fusing of the wastes (TRD 6) .
Solution mining, also referred to as in situ extraction, intro-
duces a solvent liquid into the waste mass. The hazardous (and
other) components in the waste are gathered up by the solvent and
collected for disposal or treatment on the surface from wells placed
to intercept the solvent plume. This process might be called con-
trolled leaching as the solvent behaves in a manner essentially
identical to leachate. Solvents include water, acids, and ammonia.
Various agents, such as chelating compounds (ethylene diamine tet-
racetic acid, EDTA), may be added to increase the solubility of
low-solubility substances such as heavy metals (EPA, 1982).
56
-------
2.3.4 On-Site Disposal
This approach consists essentially of building a secure dis-
posal facility on ~site, using permitted techniques. Such a site
will have to meet federal, state and local regulations for hazardous
waste treatment storage and disposal. If this approach is used, the
wastes and contaminated soils may have to be moved around the site
while the new disposal area is being constructed. For details on the
technologies for constructing secure facilities, the entire set of
TRDs should be consulted.
2.4 AIR
Historically, air contaminants (gaseous emissions or fugitive
dusts) have not received as much attention as hazardous materials in
the leachate, groundwater or surface water at uncontrolled disposal
sites. Odors, although not usually hazardous, per se, may create a
public nuisance and complicate the development of a remedial action
program addressing the hazardous problems at the site. Gaseous
emissions and fugitive dusts may be hazardous, i.e., toxic, corro-
sive, reactive, or ignitable. Continued generation of gases under a
surficial cover or cap^could lead to cracking or perforation of the
cover if pressure build-up is allowed to exceed the covering materi-
al's working limits. These direct and indirect problems require
careful assessment during site investigations and have a character-
istic set of remedial technologies quite different from those
applicable to leachate, groundwater or surface water contamination.
2.4.1 Gaseous Emissions
2.4.1.1 Source of Emissions
Gases may be emitted at a waste site by the vaporization of liq-
uids, venting of contained or entrained gases, or by chemical or
biological reactions with the solid and liquid waste materials.
Various organic compounds may slowly but continuously volatilize
from wastes at a landfill and from the exposed top surface of a sur-
face impoundment. Low boiling-point organic materials, including
contaminated solvents, if improperly contained will emit vapors
that may be ignitable or toxic. Examples of such potentially haz-
ardous emissions and their sources are given in Table 2-3 (TRD 7) .
Inorganic gases can also be emitted from a waste site. Oxidiz-
ing gases such as chlorine may react with polymeric liner materials
57
-------
TABLE 2-3
SOURCES OF GASEOUS EMISSIONS
Sources
Gases
Proteinaceous and
cellulosic wastes
Uranium mill tailings
Chemical process waste
impoundments
Industrial liquid and
sludge waste (notably
sugar beet, pulp,
tanning and chemical
process industries)
Organic decomposition gases
methane
hydrogen sulfide
Radon
Benzene
Chloroform
Trichloroethene
Other chlorinated
hydrocarbons
Methane
Methy liner cap tan
Dimethyl-disulfide
Hydrogen sulfide
and organic materials. Such gases are either chemical reaction pro-
ducts or are already present in containers or entrained in the
wastes.
Waste sludges containing organic matter, whether contained in a
discrete sludge layer (in a surface impoundment, for example) or
deposited within the subsoil in some distributed concentration (at a
land treatment facility, for example), generally undergo decomposi-
tion due to biological activity. Depending on the type of site, the
biological degradation may be either aerobic or anaerobic. Under
aerobic conditions, organic constituents are gradually oxidized to
intermediate products (for example, organic acids and alcohols) and
then converted to organic residues and gases. Under anaerobic con-
ditions, reduced sulfur, volatile intermediate products, and meth-
ane may be vented.
The rate of waste volatilization in impoundments or landfills
is dependent both on the chemical and physical properties of the
waste and also on the properties of the surrounding environment.
58
-------
Volatilization rate depends directly on vapor pressure which
increases exponentially with temperature. Vaporization of organics
from water surfaces is affected by their solubility. The rate also
depends on mixing at the surface, which depends on wind speed and
liquid turbulence." Increasing- temperatures generally reduce the
solubility and increase the emission rate into the air.
Gaseous emissions may be increased during the period when reme-
dial action operations are being undertaken. Removal of drums may
cause rupture or leakage of highly volatile or reactive materials.
Excavation or grading operations may change the biological environ-
ment, causing action to shift from anaerobic to aerobic, or vice
versa, producing new gaseous emissions. Activities at old surface
impoundments, such as pumping, dredging or excavating residue, may
lead to increased emissions due to the removal or breakup of a
dried-up surface barrier or the mixing of the surface liquid layer
with liquids of higher vaporization potential from subsurface
regions.
Gaseous emissions at the surface are mixed into the ambient air
and are transported off site by the natural dispersive properties of
the atmosphere. The gaseous emissions move from subsurface regions
to the surface by diffusion and bulk gas flow in the soil. If there
is a barrier to the flow at the surface -- for example, a man-made
cover or cap or a natural barrier -- then, unless physically con-
strained, gaseous emissions will move laterally through soil. For
example, this mechanism has been shown to result in radon buildup in
structures some distance from uranium tailings piles, and in methane
explosions in structures near landfills. Gases may also be dis-
solved in groundwater and move in both the vertical and horizontal
dimensions along with the water flow. Gas flow within the soil is
dependent on free space diffusivity, porosity and the degree of
water saturation. Soil gaseous porosity can vary by a factor of 2
from dense gravel to loose clay. Saturation may vary from a low of 2
or 3 percent in very dry soil, up to 100 percent.
2.4.1.2 Controlling Gaseous Emissions
Several remedial approaches can be used to treat gaseous emis-
sions. Removal or deactivation of all sources of emission will con-
trol the problem permanently at the site. Removal may transfer the
problems to another site, but one where means should be in place to
handle the emissions under controlled conditions. Techniques for
removal or on-site deactivation are discussed in the following
sub-section.
59
-------
Increasing moisture (for example, by irrigation) in surface and
soil layers can both reduce the rate of gaseous emissions at the sur-
face and enhance biological decay. Waste stabilization will reduce
the rate of volatilization but some gaseous products of anaerobic
decay may still permeate the waste mass and reach the surface.
Controlling emissions from surface impoundments can be effected
by stripping the entrained and dissolved gases from the liquid
wastes or conversely by increasing the gases' solubility by adding
chemicals; or mixing to disperse the gases uniformly through the
liquid layers. Emissions can be reduced by dewatering the lagoon by
draining or sometimes by adding bulking agents such as soil, cement,
or crushed coral.
Control of volatilization from the surface of landfills and
impoundments can be accomplished by covering the site, using a tem-
porary or permanent cover. Covers are usually placed directly onto
the surface of landfills. On impoundments, covers may float direct-
ly on the surface or be supported above the surface. Soil clay, syn-
thetic films and textiles, metals, and glass have been used for
covers. Floating material covers on liquid impoundments include
foams, beads, low permeability liquids, and thin plastic films.
Covers can be very effective in reducing vapor emissions as shown in
Table 2-4 (TRD 7). These data, based on a laboratory study of the
rate of vapor losses from hexachlorobenzene (HCB), indicate that
reductions of the order of 1000-fold could be obtained by using cov-
ers of soil.
If no means to control gas production within the waste mass is
provided, then the gases may build up under the cover, causing
cracking or may move laterally off the site to nearby structures.
The general approach to control this problem is to collect the gases
and vent them to the atmosphere with or without treatment, depending
on the nature of the hazard. Collection systems in landfills
include trenches, pipe vents, and barriers. Supported covers on
impoundments may also serve as gas collection systems. Trenches are
rock- or gravel-filled ditches within or around the site where the
gases entering the trench will flow to a central collection point or
will flow upward to the surface and be released directly to the
atmosphere. Pipe vents operate similarly. Perforated pipe is laid
through or around the site to intercept the permeating gases and
provide a conduit to a controlled release point.
Barriers to gas movement may be used in conjunction with col-
lection systems to channel the gas flow toward the collection
points. Barriers may be made of compacted clay or impervious plas-
tic or metal materials. Barriers can be used to prevent the lateral
60
-------
TABLE 2-4
EFFECT OF DIFFERENT COVERS ON LANDFILL HCB VAPOR EMISSIONS
HCBa Vapor Flux
Cover (kg/hectare/year)
None 317.00
1.9 cm topsoil 4.56
0.15 mm polyethylene film 201.00
1.43 cm water 0.38
120 cm topsoil 0.066
(silty clay loam)
aHCB = hexachlorobenzene
Source: TRD 7
flow above the water table through soil pores or cracks to nearby
structures. Groundwater barriers, discussed earlier, can be used to
limit the lateral transport of dissolved gases below the water
table.
Collection systems may use the natural pressure and diffusive
forces to drive the gases through the system or may include pumps.
Often the collected gases can be vented directly to the atmosphere,
using its dispersive properties to reduce their toxic or ignitable
potential to an acceptable level. If direct release is not accept-
able, the collected gases and vapors can be treated before venting
by a variety of methods including:
• physical/chemical methods;
• thermal oxidation; and
• incineration.
Adsorption removes the hazardous components by fixation on a bed of
solid sorbent, usually activated carbon. When the sorption capacity
of the bed becomes exhausted, it can be regenerated by reactivation
or be replaced with fresh sorbent.
61
-------
Absorption dissolves the undesired components from a gas in a
liquid solvent by either bubbling the gas through the liquid in
packed or plated columns, or spraying the liquid through the gas
stream in spray towers. Once the hazardous components are solubi-
lized, then any of the physical/chemical processes for treating
groundwater or leachate, described above, may be used for detoxifi-
cation.
In thermal oxidation or incineration, the undesired volatile
components are destroyed by reaction at high temperature. Thermal
oxidation generally refers to systems in which the gas supports com-
bustion on its own without auxiliary fuel. Methane emissions from
landfills can be burned in flares, a common type of burner developed
originally for natural gas and oil well control. Incinerators for
gases are often called after burners. The high temperature neces-
sary for thermal destruction of the hazardous components is achieved
by combustion of auxiliary fuel.
2.4.2 Fugitive Emissions
Fugitive emissions are particulates that are lifted from the
ground by wind and may be caused by one of the following processes:
• wind erosion of the exposed waste materials;
• re-entrainment of particulate matter by vehicular traffic
on haul roads and exposed surfaces;
• excavation of waste materials during remedial action; and
• wind erosion of the cover soil.
Wind erosion will depend on the waste type, moisture content,
wind velocity and surface geometry. Researchers generally agree
that between about 2.5 and 10 percent of all the soil eroded due to
wind becomes airborne as suspendable particulate matter (Evans, J.
et al., 1979) .
The amount of fugitive emissions generated by excavation activ-
ity is generally insensitive to the ambient wind speed, except at
very high wind speeds as in a storm. But the wind speed does deter-
mine the drift distance of large dust particles and, therefore, the
localized impact of the fugitive dust source. When remedial proce-
dures are completed, the site will often be covered with a soil layer
62
-------
that may act as a source of fugitive dust if it is not properly con-
structed to prevent this.
Fugitive dust control techniques vary according to the type of
surface encountered. Dust suppressing treatments for roadways gen-
erally include oil or calcium chloride. Excessive application of
calcium chloride should be avoided, as this compound can leach into
and contaminate groundwater. Care should be exercised in selecting
a dust control method to be sure that it does not adversely affect
the treatment process or cause environmental damage.
Wetting and stabilizing are the most commonly used techniques
for preventing and/or reducing fugitive dust emissions from exca-
vation activities. Often waste materials possess sufficient mois-
ture so that application of soil stabilizers or wetting for dust
suppression would not be required. Wet suppression, by spraying,
for example, is a fairly inexpensive, short-term method of control-
ling dust on a confined site. Gravel added to a haul road surface
acts as a physical stabilizer. Chemical stabilization uses binding
materials that cause dust particles to adhere to larger surface par-
ticles. The effectiveness of this method is extremely variable,
primarily depending on the amount of traffic.
Suppression of dust emission from soil covers can be accom-
plished by use of physical, chemical, or vegetative stabilization.
Physical stabilizers cover the exposed surfaces with a material that
prevents the wind from disturbing surface particles. Stabilizer
materials include soil, rock, crushed or granulated slag, bark, and
wood chips. The main drawback to physical covers is the high cost
involved in their application. This is especially true when the
cover materials are unavailable in the immediate area. Most chemi-
cal stabilizers only provide dust suppression for a short period of
time, generally no more than a few months. After that, a more perma-
nent solution (vegetative cover) is needed.
Vegetation may be used to stabilize a variety of exposed soil
surfaces. Vegetation provides an effective method of control along
with making the site more aesthetically acceptable. Efficiencies
close to 100 percent should be achieved with complete vegetative
covering on some sites. The soil must be prepared for vegetation by
adding fertilizers, organic matter, pH neutralizers and the estab-
lishment of proper slope and drainage. Plants compatible with the
soil type, climate, growing conditions and site end use, including
the type of maintenance expected, should be chosen. The selected
species must also be insensitive to gases that may permeate into
their root systems from continuing chemical and biological activity
in the waste mass (TRD 1, TRD 11) .
63
-------
2.4.3 Odor
Industrial wastes frequently have a characteristic odor of a
chemical nature. TKe waste can develop an extremely unpleasant odor
if the waste contains sufficient, easily decomposable organic mat-
ter and if oxygen is limited. Odor does not necessarily mean that
environmental damage is occurring but is sometimes a serious enough
problem to prevent the land treatment of waste at a site that is oth-
erwise ideally suited for the purpose.
Odors from waste material are usually a result of the formation
and release of sulfides, mercaptans, indoles, phenols, or amines,
usually under anaerobic conditions. Disposal techniques should be
designed to avoid their formation or release in the first place.
Even in fundamentally aerobic techniques such as land treatment,
some odors may occur for a short time betwen application of wastes
and its complete incorporation into the soil. Generally, the best
method to avoid odors in land treatment is subsurface injection.
If odors are present, even after attempts to prevent the forma-
tion or release of odorous emissions, odor control agents can be
used to minimize the adverse aesthetic impact. Some chemicals on
the market for odor control are listed in Table 2-5 (TRD 8) .
TABLE 2-5
ODOR CONTROL AGENTS
Type of Agent
Function
Disinfectants
Chemical Oxidants
(hydrogen peroxide)
Deodorants and Masking
Agents
To kill the micro-organisms
producing the odorous compounds;
To act as disinfectants or to
supply oxygen to microbial
population to change to
aerobic conditions;
To react with odorous gases
to prevent their release;
To impart acceptable odor;
To inactivate the olfactory
senses.
64
-------
SECTION 3
CONTROL TECHNOLOGIES
3.1 INTRODUCTION
Control technologies, discussed in this Section, operate to
confine or contain the existing region of hazardous contamination
and prevent further spread. Some operate by placing barriers to
contain the leachate or groundwater plume; others prevent contam-
ination of surface or groundwater by diverting flow away from the
contaminated region. Technologies for the physical removal of the
source of contamination also are considered control technologies.
Individual technology discussions follow the format described
in Section 1. Data requirements for all of the control technologies
are summarized in Table 3-1. Data which are of particular impor-
tance are distinguished from data which are less vital to technology
design. In addition, common sources for these data are summarized
in Table 3-2.
3.2 GROUNDWATER CONTROL TECHNOLOGIES
3.2.1 Slurry Walls
3.2.1.1 Description
Slurry walls are fixed underground physical barriers formed by
pumping slurry, usually a soil or cement, bentonite, and water mix-
ture, into a trench as excavation proceeds, and either allowing the
slurry to set (for cement-bentonite, or CB slurry) or backfilling
with a suitable engineered material (for soil-bentonite, or SB slur-
ry) . The slurry itself is used primarily to maintain the trench dur-
ing excavation. The success of the slurry wall as a barrier depends
primarily on the characteristics of the solidified CB slurry or the
engineered backfill, and to a lesser extent on the thin layer of sol-
65
-------
99
r-h
CD
l-t
B1
o
en
VO
00
O
> OT eo o
Tl ° C 3>
;* -O 3J Q.
O W
Kl t-H
o M
% V
t> h-
ftf
M
O
a
H
ft
-------
Ml
Ct
fD
t-t
o
CD
CO
O
s
?o«gon«o w »§"co5£'ioc',fS1
— £ O — | w w Q "g — ^•^(T>_S2.2~~~^^IS
l-> M 3 ° 5L>28^;?;;g;f™gI,l
^ "DO °Q?rc6^O£T^ ~ CO
•?> wSSSSagB s - c g> 8 a o
> 2 c n S-
eg g S =• <
0 S
S w
CD
31
.... . .
. ...
• * . • .
. ... . .
. . . . .
. . . . .
• • . . .
. . . . ...
. ... . .
. . . . .
* . . . .
. . . . .
. . . . .
. . . . •
. . . . •
. . . • •
. . . . .
. ...
. .
. . .
. . .
.
. .
. .....
. ...
^ w
...
. . .
. • .
. . • •
. .
.
. . ...
.
. . .
....
....
...
. .
? S? S 7
sj c ** 3
o I -3
c
8
(D
Topography
Accessibility of Site or Materials
Vegetation Characteristics
Rock Type
Structural Characteristics
Thickness of Strata
Depth to Impermeable Strata
Hydraulic Conductivity
Type (Texture)
Grain Size Distribution
Compaction
Strength Properties
Erosion Potential
Moisture Content
Permeability
Porosity
Depth
Chemistry
Precipitation (Rainfall Parameters)
Evapotranspiration
Storm Characteristics
Wind Characteristics
Temperature
Air Quality
Depth to Watertable
Potentlometric Surfaces [
Direction and Rate of Flow
Recharge Quantity
Aquifer Characteristics
Chemistry
Infiltration
Runoff
Depth of Flow
Drainage Area
Flood Characteristics
Sedimentation
Chemical Characteristics
Physical Characteristics
Disposal Practices
Regulations
Other
n
1
f
n
A
O_
1
o
tfi
0
f
Q)
o
0
a
O
o
c
a
a
*
S
n
-------
idified slurry (or filter cake) that adheres to the trench wall
during construction. Slurry walls can be used to:
• contain contaminated groundwater;
• divert a contaminated groundwater plume away from a drink-
ing water intake or towards a treatment facility;
• divert uncontaminated groundwater flow around a (poten-
tially) contaminated area; and
• provide a hydrologic barrier for a groundwater treatment
system.
A typical slurry wall is shown in Figure 3-1
3.2.1.2 Status
Conventional, demonstrated. However, new techniques are being
developed.
3.2.1.3 Feasibility and Effectiveness
General
Slurry wall characteristics should be compatible with in situ
soil, groundwater, and leachate conditions.
Permeability of the entire wall depends both on the formation of
a filter cake on the trench wall during construction and on the back-
fill used. Total permeability of the wall (k) is given by the
equation in Figure 3-2. (D1Appolonia, 1980). This equation is
plotted in Figure 3-2 for various values of kc/tc. As can be seen,
when the backfill permeability is very low, the filter cake has lit-
tle effect. However, when backfill permeabilities are higher,
filter cake permeability becomes quite significant, limiting the
total permeability of the wall to no more than 10~6 cm/sec. This
result, however, assumes that a proper bentonite slurry is used and
the upstream filter cake does not rupture but stays intact
(D'Appolonia, 1980).
68
-------
FIGURE 3-1
CONSTRUCTION OF A BENTONITE SLURRY WALL
(Source: Sommerer and Kitchens, 1980)
Backhoe
Keys Trench
I into
L Clay Layer
-------
FIGURE 3-2
THEORETICAL RELATIONSHIP BETWEEN WALL PERMEABILITY
OF FILTER CAKE AND BACKFILL
(Source: D'Appolonia, 1980)
Used by permission, see Copyright Notice
k =
k = wall permeability
2t k = cake permeability
C C
kc kb = backfill permeability
tb = backfill thickness
10"
.a
ro
a>
i_
CD
a.
10
-7
10
-8
c _
t = cake thickness
C
25X10~9/sec
X 10~9/sec
5X 10~9/sec
Wall Thickness = 80 cm
I i
10"
10"
10
-6
10
-5
10
.-4
10"
Backfill Permeability
k, cm/sec
Slurry walls, where possible, should extend to bedrock or- a
stratum with permeability as low as that of the wall to be effective.
See the discussion in Section 2 concerning the use and effectiveness
of impermeable barriers.
Trench Excavation
Proceeds either continuously or by panel, depending on equip-
ment used, backfill characteristics, shape of wall, and other
site-specific conditions.
Minimum trench width is determined by the type of equipment used
for excavation. For all equipment, a minimum width of .6 meters (2
feet) is recommended (D'Appolonia, 1980).
70
_T_
-,-) *:= -—
-------
Continuity of the excavation should be checked prior to back-
filling. In particular, the trench should extend at least .6 meters
(2 feet) into underlying soil material, and underlying rock surfaces
should be scraped clean by excavating tools. Accumulated sediment
from the slurry, however, does not need to be removed unless it is
significantly different from the backfill material (D!Appolonia,
1980).
Slurry Characteristics
The most important slurry property is viscosity. A minimum vis-
cosity of 40 sec-Marsh is usually needed for trench stability and
good filter cake formation (D1Appolonia, 1980). Density (unit
weight) and volume are also important slurry properties.
Unit weight of SB slurry should be 240 kg/m3 (15 lb/ft3) lighter
than the backfill material for the backfill to properly displace the
slurry. Typical SB slurry is, therefore, 1440 to 1680 kg/m-1 (90 to
105 lb/ft3) • Unit weight for CB slurry is usually around 1920 kg/m3
(120 lb/ft3). Density, however, is not as important as for SB
slurry, since no backfilling is required. CB slurry achieves final
set within 90 days of placement (Sommerer and Kitchens, 1980) .
Volume of slurry required, as suggested by Xanthakos (1979) is:
„ _ Ve ^ Ve /, kM ,„ n% , k2 „
v ' 100
\ '
where:
Vs = volume of slurry required
Ve = total volume of excavation
n = number of panels to be constructed in the cutoff
kj = rate of slurry recovery during emplacement, %
k2 = rate of slurry loss, %, during emplacement
Slurry additives may be used to modify slurry characteristics
as appropriate. Additives are available to increase density,
increase or decrease viscosity and gel strength, prevent floccula-
tion, decrease fluid loss, and improve slurry circulation. For more
detailed information, see Xanthakos, 1979.
71
-------
Backfill Characteristics
Permeability of SB backfill material decreases with fines con-
tent (percent passing a No. 200 sieve). In addition, plastic fines
result in a permeability up to two orders of magnitude lower than
non-plastic or low plasticity fines (D*Appolonia, 1980). This
relationship is shown in Figure 3-3.
Bentonite concentration also greatly affects backfill permea-
bility. A minimum bentonite content of 1 percent with at least 20
percent fines is recommended. To make sure that the backfill con-
tains adequate bentonite, either water content of the soil prior to
mixing with bentonite slurry should be controlled, or dry bentonite
should be added (D1Appolonia, 1980).
When compressibility and strength of the slurry wall is impor-
tant, e.g. , under a levee, SB backfill should be granular with 20 to
40 percent plastic or clayey fines. This optimizes permeability and
compressibility (D1Appolonia, 1980).
Backfill consistency at time of placement should correspond to
a slump test reading of 50 to 150 mm (D1Appolonia, 1980). In the
slump test, the backfill is molded into a cone 12-inches high with an
8-inch diameter base and a 4-inch diameter top (ASTM Specification
C143) . The change in height of the cone after the mold is removed is
the measured slump (Merritt, 1976). In addition, backfill should be
placed or poured, not dropped, into the trench to avoid trapping
pockets of slurry and separating of coarse and fine soils (Sommerer
and Kitchens, 1980) .
Special Precautions and Limitations
The bentonite should be completely hydrated and well-mixed with
the soil or cement before being placed into the trench (Sommerer and
Kitchens, 1980).
Compatibility of backfill materials with leachate should be
carefully tested. In particular, it should be determined whether
the bentonite or the soil matrix tend to dissolve in the leachate.
Backfill material should be chosen to minimize the effect of the
leachate. Adjusting the content of plastic fines can keep changes
in permeability due to leachate within tolerable limits. In addi-
tion, it may be preferable to use soils that are already
contaminated in the backfill since they may undergo less alteration
72
-------
FIGURE 3-3
PERMEABILITY OF SOIL-BENTONITE BACKFILL RELATED TO FINES CONTENT
(Source: D'Appolonia, 1980)
Used by permission, see Copyright Notice
80
70
60
vP
50
C
4°
cS
trt
I 30
20
10
Plastic Fines
Non-Plastic or Low
Plasticity Fines
10
-9
10~a ID"' 10"° 10
SB Backfill Permeability, cm/sec
-5
10
-4
due to leachate permeation (D'Appolonia, 1980). The effect of the
contaminated soil on the backfill and the filter cake, however,
should be carefully tested. The effect of various pollutants on SB
backfill permeability is given in Table 3-3.
3.2.1.4 Principal Data Requirements
Accessibility of suitable soil and bentonite (cost, imple-
ment ability)
Depth to low-permeability stratum or bedrock (optimal depth
of wall)
Soil characteristics (suitability of soil for use in SB
slurry or backfill; expected lifetime and effectiveness of
the wall) :
• texture - granular or cohesive
73
-------
TABLE 3-3
PERMEABILITY INCREASE DUE TO LEACHING
WITH VARIOUS POLLUTANTS
SB Backfill (silty or clayey)
Pollutant Filter Cake sand) 30% to 40% Fines
(1) (2) (3)
CA-H- or Mg-H- at 1,000 ppm
CA-H- or Mg-H- at 10,000 ppm
NH,N03 at 10,000 ppm
HCL (1%)
H2S04 (1%)
HCL (5%)
NaOH (1%)
CaOH (1%)
NaOH (5%)
Sea water
Brine (SG = 1.2)
Acid mine drainage (FeSO, ;
pH -x. 3)
Lignin (in CA-H- solution)
Alcohol
N
M
M
N
M
M/HS
M
M
M
N/M
M
N
N
H (failure)
N
M
M
N
N
M/Ha
M
M
M/HH
N/M
M
N
N
M/H
o
Significant dissolution likely.
Note: N = no significant effect, permeability increase by about a factor
of 2 or less at steady state; M = moderate effect, permeability increase
by factor of 2 to 5 at steady state; H = permeability increase by factor
of 5 to 10.
Source: D'Appolonia, 1980
• grain size distribution and gradation
• moisture content
• permeability
• soil pressure
Groundwater characteristics (construction requirements,
such as additives and required strength; lifetime of wall)
• depth to water table
• direction and rate of flow
74
-------
pH
• hardness
• salt concentration
• presence of other minerals and organics
• water pressure
• leachate chemistry
3.2.1.5 Elements of Cost Review
Components
Construction and Capital--
• laboratory and field testing
• trench excavation
• slurry mixing
• backfilling
• transportation of material
• slurry material
• backfill material
• slurry additives
O & M--
• Monitoring
Major Factors
• excavation method
-------
• length and depth of wall
• transportation distance for bentonite, other soil
• type of slurry and backfill used
Data
Unit costs for a slurry wall are usually given in square feet
(length x depth). When a backhoe can be used for excavation, a unit
cost as low as $2-3/ft^ is possible. Depending on other factors,
costs may be as high as $8-10/ft^.
3.2.2 Grout Curtains
3.2.2.1 Description
Grout curtains are fixed underground physical barriers formed
by injecting grout, either particulate (such as Portland cement) or
chemical (such as sodium silicate), into the ground through well
points. Grout curtains can be used to:
• contain contaminated groundwater;
• divert a contaminated groundwater plume away f r'om a drink-
ing water intake or towards a treatment facility; and
• divert uncontaminated groundwater flow around a (poten-
tially) contaminated area.
3.2.2.2 Status
Conventional, undemonstrated. Grout curtains are useful only
under certain site specific conditions, and it is difficult to veri-
fy whether a contiguous curtain has been formed.
3.2.2.3 Feasibility and Effectiveness
76
-------
FIGURE 3-4
TYPICAL THREE-ROW GRID PATTERN FOR GROUT CURTAIN
(Source: Sommerer and Kitchens, 1980)
\
!
o /)
°
X
° °
i.8 r
)
L5r
Construction
Grout curtains are typically formed by injecting grout through
pipes in a pattern of two or three adjacent rows, as shown in Figure
3-4.
Pipe spacing depends on the radial distance of grout pene-
tration, r (cm), where:
r = .62 3/Q~T
n
and:
77
-------
Q = rate of grout injection (cm3/min)
n = porosity of soil (unitless)
t = pumping time or gelation time (min)
Space between ajacent pipes should be ^2r (Sommerer and
Kitchens, 1980).
The rate of injection should be carefully chosen depending on
site-specific characteristics. Excessively slow rates result in
premature grout/soil consolidation, and excessively rapid rates
result in fracturing of the soil formation.
A variation for grout curtain installation is the vibrating
beam technique. Although it is sometimes called a slurry wall tech-
nique, it is closer to a grout curtain variation since the slurry is
injected through a pipe similar to grouting. A suspended I-beam,
connected to a vibrator, is inserted into the ground. Slurry is then
injected under pressure through a set of nozzles located at the base
of the vibrated beam. At the completion of a panel, the rig is moved
along the direction of the wall, and the process is repeated. The
previous insertion is overlapped to provide continuity, but the bar-
rier is only 10 cm (4 in. ) thick.
Grout Material
Important characteristics of various grout materials are given
in Table 3-4 and Table 3-5, and Figure 3-5. Information on bitumen
grouts and other more recent polymer grouts, such as urethane and
epoxy resin, is not included.
Selection of grout material depends on:
• soil permeability (see Figure 3-6);
• soil grain size (see Figure 3-7);
• rate of groundwater flow;
• chemical constituents of soil and groundwater;
• grout strength required; and
• cost
78
-------
TABLE 3-4
TYPES OF GROUT
Significant
Characteristics
Cost Relative To
Portland Cement
Portland Cement or
Particulate Grouts
Chemical Grouts
Sodium Silicate
Phenoplasts
Lignosulfonate
Derivatives
-Appropriate for higher permeability
(larger grained) soils;
-Least expensive of all grouts when
used properly;
-Most widely used in grouting across
the U.S. (90% of all grouting).
-Most widely used chemical grout
-At concentrations of 10-70% gives
viscosity of 1.5 - 50 cP
-Resistant to deterioration by
freezing or thawing;
-Can reduce permeabilities in sands
from 10~2 to 10~8 cm/s;
-Can be used in soils with up to 20%
silt and clay at relatively low
injection rates;
-Portland cement can be used to
enhance water cutoff
-Rarely used due to high cost
-Should be used with caution in
areas exposed to drinking water
supplies;
-Low viscosity;
-Can shrink (with impaired
integrity) if excess (chemically
unbound) water remains after
setting; unconfined compression
strength of 50-200 psi in
stabilized soils.
-Rarely used due to high toxicity
-Lignin can cause skin problems and
hexavalent chromium is highly
toxic; both are contained in these
materials;
-Cannot be used in conjunction with
Portland Cement: pH's conflict;
-Ease of handling;
-Lose integrity over time in moist
so il s;
-Initial soil strengths of 50-200 psi.
1.0
2.0-5.0
N.A.
1.65
(Cont.)
79
-------
TABLE 3-4
TYPES OF GROUT (Cont.)
Significant
Characteristics
Cost Relative To
Portland Cement
Aminoplasts
e.g., urea-
formaldehydes
Acrylamid Grouts
-Rarely used due to high cost N.A.
-Will gel with an acid or neutral
salt;
-Gel time control is good
-Rarely used due to toxicity 4.0-10.0
-Should be used with great caution
near to drinking water supplies;
-Readily soluble in water;
-Manufacter in USA prohibited
available as AV-100 from
Japan;
-Can be used in finer soils than
most grouts because low viscos-
ities are possible (1 cP);
-Excellent gel time control due to
constant viscosity from time of
catalysis to set/gel time;
-Unconfined compressive strengths
of 50-200/psi in stabilized soils;
-Gels are permanent below the water
table or in soils approaching 100%
humidity;
-Are vulnerable to freeze-thaw and
wet-dry cycles, particularly
where dry periods predominate and
will fail mechanically;
-Due to ease of handling (low vis-
cosity) , enables more efficient
installation and is often cost-
competitive with other grouts.
Specific grout products and their properties are listed in Table 3-5.
From: Kirk and Othmer, 1979; Sommerer and Kitchens, 1980; and GZA, 1982
80
-------
TABLE 3-5
GROUT PROPERTIES
GROUT MATERIAL
SILICATE BASE
LOW CONCENTRATION
LOW CONCENTRATION
LOW TO HIGH
CONCENTRATION
LOW TO HIGH
CONCENTRATION
LOW TO HIGH
CONCENTRATION
LOW TO HIGH
CONCENTRATION
LOW TO HIGH
CONCENTRATION
LOW TO HIGH
CONCENTRATION
LIGNIN BASE
BLOX-ALL
TDM
TERRA-FIRMA
LIGNOSOL
FORMAL DEHYDE BASE
UREA-FORMALDEHYDE
UREA-FORMALDEHYDE
RESORCINOL FORMAL-
DEHYDE
TANNIN-PARA-
FORMALDEHYDE
GEOSEAL MQ-4 &
MQ-5
UNSATURATED FATTY
ACID BASE
POLYTHIXON FRD
CATALYST
MATERIAL
BICARBONATE
HALLIBURTON CO.
MATERIAL
SIROC-DIAMOND
SHAMROCK
CHEMICAL CO.
CHLORIDE-JOOSTEN
PROCESS
ETHYL-ACETATE
SOLETANCHE &
HALLIBURTON
RHONE-PROGIL
600
GELOC-3
H. BAKER CO.
GELOC-3X
HALLIBURTON CO.
MATERIAL
CEMENTATION CO.
MATERIAL
INTRUSION CO.
MATERIAL
LIGNOSOL CO.
MATERIAL
HALLIBURTON CO.
MATERIAL
UNCONFINED COMPRESSIVE
STRENGTH (PSI) OF
GROUTED SOIL
10-50
10-50
10-500
10-1000
10-500
_
10-500
10-250
5-90
50-500
10-50
10-50
OVER 1000
AMERICAN CYANAMID OVER 500
CO. MATERIAL
CEMENTATION CO.
MATERIAL
BORDEN COMPANY
MQ-8
BORDEN COMPANY
MATERIAL
CEMENTATION CO.
MATERIAL
OVER 500
OVER 500
SETTING
VISCOSITY TIME
(CENTIPOISE) MINUTES TOXICANT* POLLUTANT**
1.5 0.1-300 NO NO
1.5 5-300 NO NO
4-40 5-300 NO NO
30-50 0 NO NO
4-40 5-300 NO NO
_
4-25 2-200 NO NO
4-25 0.5-120 NO NO
8-15 3-90 YES YES
2-4 5-120
2-5 10-300 YES YES
50 10-1000 YES YES
10 4-60 YES YES
13 1-60 YES YES
3.5 - YES YES
10-80 25-360 NO NO
* - A material which must be handled using safety precautions and/or protective clothing.
** - Pollutant to fresh water supplies contacted.
Source: Hallburton Services, 1976
81
-------
FIGURE 3-5
VISCOSITIES OF VARIOUS GROUTING MATERIALS AS A FUNCTION OF GROUT
CONCENTRATION (the solid lines represent the concentration normally used)
(Source: Sommerer and Kitchens, 1980)
10
20 30
Concentration or Percent Solids
40
50
a. No longer manufactured.
82
-------
FIGURE 3-6
CORRELATIONS BETWEEN SOIL GRAIN SIZE, PERMEABILITY AND POTENTIAL DEWATERING METHODS
(Source: Sommerer and Kitchens, 1980)
00
OJ
1 10 10 10 J 10~* 10~b 10~D
I I 1 I I I I
! 1 1 III III |
2 .6 .2 .1 .06 .02 .01 .006 .002
Effective Grain Diameter, d.Q
Gravel Co Sand | Md Sand | Fl Sand Ca Silt Md Silt j Fl Silt |
Clean Gravels ___ ( ( Very Fine Sands (
( Clean Sands § , Silts, Organic and Inorganic
Coarse Fine
I Sand, Gravel Mixtures, Till i Varved Clays, etc.
Horizontal
, ^ Sand-Silt-Clay Mixtures, Till
*
Cohesionless except for Cementation Variable Cohesion Cohesiv
10~7 10~a cm
I I
I I I
.001 .0006 nm
Clay I MIT Grades
.^ Permeability
Ranges of
Typical Real
I Soils
M
Vertical
*"
e Cohesion Characteristics
Excessive water / Large dia. walls / 11
yields, wide / wide spacing / Vacuum systems, low yields / Vacuum plus/ Dewatering usually
spacing / Educator walls, / narrow spacing /electroosmosis/ not required
/ narrow spacing/ / /
/ 1 /
. ,„ ... "7 / / Electroosmosis, electrochemical stabilization
Loss of Compressed Air / / /
Possible Dewatering Methods
Sand Cement Freezing possible throu9hout
Cffmfint «»H^n. Colloid grouts ^^^^. Polymers Rpsins
Bituminous Grout —_^__ __^__ Grouting in fissures
Bentonite — ^__
Suspensions Colloidal Solutions
Lower Grouting
Boundaries
-------
FIGURE 3-7
SOIL GRAIN SIZE LIMITS FOR GROUT INJECTABILITY
(Source: Haliburton Services, 1976)
Used by permission, see Copyright Notice
GRAVEL
Fine
SAND
Coarse
| |
Medium
Fine
..
n
ICE
Ceme
nt
Be
1
ISilic
nton
te
1
3tes
COARSE SILT
SILT (NON-PLASTIC)
Clay - Soil
is
|Cc
jmpre
i
Sub-Aquec
us Ex
ca
i/ati
on —
Heavy PL
1
mp
II
in
] Wellpoints —
T"
1
1
1
III
r
V
Cie
JCU
d
um
Syste
'm Neede
II
d i
fQ
ui
:k
^or
ditio
ssed Air
Freez-
ing
ns Exist
Wellpoints — Theoretical Limits for Gravity Damage
w
ell
poir
ts-(
jravity D
rai
lac
e
Ve
yS
ow
Wellpoint Vacuum System
1 I I 1 I
ectro
Po
-osmosis
ssible
10.0
1.0
0.1
Grain Size in Millimeters
0.01
0.001
In situ Requirements
Soil is not considered suitable for grouting if more than 20
percent of the soil passes through a No. 200 sieve. Low viscosity
grouts are required if more than 10 percent of the soil passes
through a No. 200 sieve (Sommerer and Kitchens, 1980).
Groundwater flow can adversely affect the integrity of a grout
curtain, particularly during construction. Special consideration
should be given to rate of flow and chemical composition of the
groundwater (Sommerer and Kitchens, 1980).
84
-------
Special Precautions and Limitations
Grout curtains should extend to an impervious (or bedrock) lay-
er to be effective. See discussion in Section 2 concerning use and
effectiveness of groundwater barriers.
Maximum effective depth is limited by depth of the injection
well or site specific constraints.
3.2.2.4 Principal Data Requirements
Accessibility of grout equipment and materials (implement-
ability and cost)
Depth to low permeability stratum or bedrock (optimal depth
of wall)
Soil characteristics (soil groutability, grout
penetration, rate of injection, grout material selection)
• grain size distribution
• moisture content
• permeability
• porosity
• chemistry
Groundwater characteristics (grout material selection,
wall construction)
* depth to water table
• direction and rate of flow
pH
• concentration of sulfides, calcium
• leachate chemistry
Grout characteristics (barrier performance)
• strength properties
85
-------
• viscosity
• gelation time
3.2.2.5 Elements of Cost Review
Components
Construction and Capital--
• laboratory and field testing
• well drilling
• grout injection
• grout material
0 & M—
• Monitoring
Major Factors
• length and depth of wall
• number of wells per row of grid pattern
• number of rows in grid pattern
• grout material
Data
Unit costs of various grout materials are given in Table 3-6.
Total cost for a grout curtain 720 meters (2400 ft. ) long and 15
meters (49 ft. ) deep with a 2-row grid chemical grout and wells every
1.8 meters (6 ft.), in 1982 dollars, is 7.5 million to 15.1 million
dollars, or 231 to 466 $ /m3 of grout curtain.
86
-------
TABLE 3-6
UNIT COSTS OF GROUTS
Approximate Cost, 1982 Dollars
Grout Type $/Gallon of Solution
Portland Cement 1.05
Bentonite I-38
Silicate - 20% I-93
- 30% 2.31
- 40% 3.03
Lignochrome 1.71
Acrylamide 7.32
Urea Formaldehyde 6.27
Source: EPA, 1982
3.2.3 Sheet Pile Cutoff Walls
3.2.3.1 Description
Sheet piling cutoff walls are constructed by driving web sec-
tions of sheet piling permanently into the ground. Each section is
interlocking at its edges by either a socket or bowl and ball joint.
Sections are assembled before being driven into the ground and ini-
tially are not watertight. However, the joint connections soon fill
with fine- to medium-grained soil particles, generally blocking
groundwater flow. Sheet piling cutoff walls can be used to:
• contain contaminated groundwater;
• divert a contaminated plume away from a drinking water
intake or towards a treatment facility; and
• divert uncontaminated groundwater flow around a (poten-
tially) contaminated area.
Various sheet pile cross-sections are shown in Figure 3-8.
87
-------
Aj
FIGURE 3-8
SHEET PILING SECTION PROFILES
(Source: EPA, 1982)
Straight Web Type
Arch Web Type
88
Deep Arch
Web Type
Z-Type
Y-Fitting
o
T-Fitting
-------
3.2.3.2 Status
Conventional, demonstrated.
3.2.3.3 Feasibility and Effectiveness
General
Maximum effective depth is considered to be 15 meters (49 ft),
although pile sections have been driven up to depths of 30 meters (98
ft)(Sommerer and Kitchens, 1980).
Steel sheet piling is most frequently used. Concrete and wood
have also been used. Concrete is expensive but is attractive when
exceptional strength is required; and, although less expensive,
wood is relatively ineffective as a water barrier (EPA, 1982) .
Sheet piles are typically used in soils that are loosely packed
and predominantly sand and gravel in nature. A penetration resist-
ance of 4 to 10 blows/foot for medium- to fine-grained sand is recom-
mended (Terzaghi and Peck, 1948).
Piling lifetime depends on waste characteristics and pile mate-
rial. For steel piles pH is of particular importance. Ranges of pH
from 5.8 to 7.8 enables a lifetime up to 40 years (depending on other
leachate characteristics), and pH as low as 2.3 can shorten the
lifetime to 7 years or less (EPA, 1982).
Special Precautions and Limitations
Sheet pile cutoff walls should extend to bedrock or other
impermeable strata to be effective. See the discussion in Section 2
concerning the use and effectiveness of groundwater barriers.
3.2.3.4 Principal Data Requirements
Depth to low-permeability stratum or bedrock (optimal depth
of wall)
Soil characteristics (soil suitability for sheet pile use)
89
-------
• grain size distribution
• compaction
Groundwater characteristics (pile lifetime, placement)
• depth to water table
• pH
• leachate chemistry
3.2.3.5 Elements of Cost Review
Components
Construction and Capital--
• installation
• shipping
• piling material
0 & M--
• Monitoring
Major Factors
• length and depth of wall
• piling material used
Data
Unit costs for sheet piling and installation are shown in Table
3-7.
90
-------
TABLE 3-7
SHEET PILING UNIT COSTS
Assumptions 1982 Costs
Sheet Piling Black steel $l,300/ton
Hot dipped galvanized steel 1,500/ton
(5 gage dimensions: 19.6 in.
laying width, 3.18 in. front
to back, and 20 ft. long)
Installation 280/ton
Source: EPA, 1982
Total cost for a sheet piling cutoff wall 720 meters (2360 ft)
long and 15 meters (49 ft) deep in 1982 dollars is $612,000 to
902,000 (SCS, 1980).
3.2.4 Block Displacement Method (BDM)
3.2.4.1 Description
Block Displacement is a method for placing a fixed underground
physical barrier around and beneath a large mass of earth (called a
block). The bottom barrier is formed when fractures (or
separations) extending from horizontal notches at the base of the
injection holes coalesce into a larger separation beneath the mass
block of earth. Continued pumping of slurry under pressure produces
a large uplift force against the bottom of the block and results in
vertical displacement proportional to the volume of slurry pumped.
A perimeter barrier around the, block is constructed by conven-
tional techniques in conjunction with the bottom barrier either pri-
or to or following bottom barrier construction. The perimeter wall
constructed prior to bottom separation can be used to ensure a
favorable horizontal stress field for proper formation of the bottom
91
-------
separation. In geologic formations not requiring control of hori-
zontal stress, the perimeter may be constructed following initial
bottom separation or following the completion of block lift.
The Block Displacement Method can be used to:
• contain contaminated groundwater;
• divert uncontaminated groundwater flow around a (poten-
tially) contaminated area; and
• lower the water table inside the isolated area.
A typical BDM barrier is shown in Figure 3-9.
3.2.4.2 Status
Developmental. Verification of the bottom barrier is now in
progress.
3.2.4.3 Feasibility and Effectiveness
General
The Block Displacement Method is of particular value in stratum
where unweathered bedrock or other impermeable continuum is not suf-
ficiently near the surface for a perimeter barrier alone to act as an
isolator.
Permeability of the bottom barrier depends both on the filter
cake that forms on the separation surfaces and on the permeability
of the residual slurry which consolidates with time. As water in the
residual slurry leaks off with time, the permeability of the entire
barrier approaches that of the filter cake. Permeabilities of 10~8
cm/sec are attainable with proper slurry design.
The effectiveness of the bottom barrier is based on the permea-
bility of the consolidated slurry material and the thickness of the
barrier.
92
-------
FIGURE 3-9
BLOCK DISPLACEMENT METHOD
SLURRY
INJECTION
• *
PERIMETER
SURCHARGE
(WHEN
REQUIRED)
PERIMETER
SEPARATION
4 M 4
INJECTION
HOLES X
UPLIFT
/ PRESSURE \
lit »iii
H
Hit
iiUit
MtHi
PERMEABLE SOIL
COALESCING
SEPARATIONS
a) CREATING THE BOTTOM SEPARATION
GROUNDWATER LEVEL
LOWERED
GROUNDWATER ,
LEVEL
A
4 ' < PERIMETER
-i ) BARRIER
POSITIVE SEAL THROUGH
INJECTED BENTONITE
MIXTURE
BOTTOM BARRIER
b) CONFIGURATION OF FINAL BOTTOM AND PERIMETER BARRIERS
93
-------
Effectiveness of the perimeter barrier is dependent on the per-
imeter construction technique. (See other sections describing
groundwater barrier techniques. ) In general the perimeter should be
designed with an overall effectiveness compatible with the effec-
tiveness of the bottom barrier.
Bottom Barrier Construction (Brunsing, et.al., 1982)
Construction of the bottom barrier proceeds in four phases: (1)
Formation of notches at the base of the injection holes; (2) Initial
bottom separation at the notched holes; (3) Propagation of the local
separations at each injection point coalescing into a single larger
bottom separation; (4) Generation of a complete bottom barrier by
controlled vertical displacement of the earth mass using low pres-
sure slurry injection into the horizontal separation. Each of the
these phases is carried out through control and monitoring of slurry
pressure, slurry flow rate, total volume injected, and slurry compo-
sition. The notching operation (1) requires a high pressure
rotating jet at the base of the injection. The jetting slurry must
be composed in a manner which optimizes notch erosion, removes cut-
tings, and minimizes leak off into the soil. The initiation of
bottom separation (2) requires a slurry pressure, P0 , defined by:
P = p gh + AP
o Hr^
where: p is the average earth mass density
g is the gravitational constant
AP is the pressure in excess of the overburden
h is the depth of the bottom separation
AP increases with increasing slurry viscosity and decreasing
notch radius and in general depends on soil characteristics. The
bottom separation is initiated when a slurry flow at a fixed Po
occurs.
Separation coalescence (3) is brought about by adding slurry
volume and by gradually increasing the viscosity of the slurry.
Slurry pressure required to propagate the horizontal separation
will reduce during this phase due to the increased area over which it
is acting. Increasing the viscosity of the slurry serves to limit
f]ow in preferential directions.
94
-------
Vertical displacement (4) utilizes the maximum capacity of the
pumping equipment, along with a high solids slurry that will form
the final barrier. The pressure required to continuously increase
the barrier thickness by lifting the buoyed block eventually
decreases. When a "perimeter barrier is constructed prior to dis-
placement, the injection pressure approaches that required to
balance the resistance of the fluid in the perimeter (A P2) and to
overcome fluid drag in the bottom separation (APj) (Cleary, 1979).
The final pressure relationship is:
AP
AP2 + —L = (pr ~ V g
n
where: p is the density of the mud in the perimeter barrier
n depends on the number of injection holes
( = 3 for a single central hole)
Bottom barrier construction proceeds simultaneously or by sec-
tion from multiple injection points depending on size of site, geol-
ogy, and perimeter barrier technique used.
Bottom barrier thickness can vary from a few centimeters to more
than a meter. The thickness is increased by further pumping of slur-
ry down injection holes. Selective pumping coupled with a high vis-
cosity slurry design enables relative variation or adjustment to
bottom barrier thickness during block displacement.
Continuity of the bottom barrier can be checked by pressure com-
munication between injection holes and by surface level survey dur-
ing block displacement.
Verification of barrier completeness can be attained following
perimeter and bottom construction by long term monitoring of draw
down within the isolated block. If deemed necessary, continued
pumping can further increase the bottom thickness locally or in gen-
eral until satisfactory verification results are attained.
Perimeter Barrier Construction
Construction of the perimeter barrier begins with the con-
95
-------
struction of a perimeter separation which can proceed using one of
several standard techniques, as mentioned earlier. The thickness of
the perimeter separation can be less than the final thickness, by
placing the separation at a small angle to the vertical so that the
sides are convergent downward. Thus, the thickness of the sides
will increase by w when the block is vertically displaced by d
according to:
w = d sin
where is the angle of the perimeter barrier measured from the ver-
tical .
The perimeter separation must be made deep enough to intersect
the bottom separation. If the perimeter is installed after the bot-
tom separation is created, the intersection will be determmined when
slurry flows from the bottom up the perimeter. If the perimeter sep-
aration is installed prior to the bottom separation, it must be made
deep enough to insure that this intersection will take place. In
certain soil conditions, creating the bottom separation requires
the use of heavy mud in the perimeter separation to add horizontal
stress in the block. Under these conditions the perimeter sepa-
ration must be made deep enough so that the horizontal stress can be
fully transmitted through the block at the bottom separation level.
Slurry Characteristics
The various functions of the slurries used can be summarized as
follows:
1. Bottom Barrier Construction
• notching
• initiating bottom separation
• propagation and coalescing of bottom separation
• block lift and final barrier construction
2. Perimeter Barrier Construction
• soil stabilization during construction of perime-
ter separation
96
-------
pressure surcharge for increasing horizontal
stress
gel strength to resist leak off during block lift
ancl final barrier construction
Table 3-8 lists these various functions along with the range of
slurry properties applicable to each function. The quality require-
ments for the material representing the final barrier are equivalent
to those for other bentonite clay based barrier and sealing tech-
niques (see Table 3-3) .
Special Precautions and Limitations
The barrier should be compatible with in-situ soil,
groundwater, and leachate conditions.
3.2.4.4 Principal Data Requirements
Accesibility of Suitable Soil and Bentonite (cost and imple-
ment ability)
Soil characteristics (suitability of soil for use in soil ben-
tonite slurry; expected lifetime and effectiveness of the barrier):
• discontinuitie-s in soil strata in region of expected bottom
barrier construction
• cohesive and consolidation states of individual strata
• degree and orientation of soil stratification and bedding
• absolute value and variation of soil permeability in indi-
vidual strata
• proximity of weathered bedrocks or solution channels to
expected bottom barrier region
• texture and grain size distribution
• moisture content
• soil pressure
97
-------
TABLE 3-8
SLURRY CHARACTERISTICS FOR THE BLOCK DISPLACEMENT METHOD
FUNCTION
Bottom Barrier Construction
i) Notching
ii) Initiating bottom separation
iii) Propagation and coalescence
iv) Lift and final barrier
Perimeter Barrier Construction
i) Stabilization
ii) Surcharge (when placed prior
to lift)
iii) Gel strength and final barrier
DENSITY
(Sp. Gr.)
1.1 - 1.3
1.1 - 1.3
2.0 - 3.0
1.8 - 1.9
1.5 - 2.5
1.9 - 2.0
1.8 - 1.9
GEL
STRENGTH
(Pa)
10 - 20
10
20 - 50
50 - 100
20
200
50 - 100
PERMEABILITY WHEN
CONSOLIDATED
(cm/sec. )
Based on permis-
sible leak off &
soil characteris-
tics.
»
II
10~7 - 10~8
Based on permis-
sible leak off &
soil properties
it
depends on thick-
ness
COMMENTS
Must match notching
tool jet design.
Low viscosity slurry
desired.
High viscosity but
pumpable.
Indicated values for
med. grain sand-varies
according to soil pro-
perties .
Max. density desired,
flow requirements
minimal .
Total barrier perme-
ability and thickness
should match the ef-
fectivenss of the bot-
tom barrier.
00
-------
Groundwater characteristics (construction requirements, such
as additives and required strength; lifetime of barrier):
• depth of watertable
• direction and rate of flow
pH
• hardness
3.2.4.5 Elements of Cost Review
Components
Construction and Capital--
• slurry material
• transportation of material
• drilling and casing
• notching
• slurry injection plumbing
• slurry mixing
• pumping
• instrumentation, control, and verification
O & M—
• Monitoring
Major Factors
• size of the earth mass to be displaced
• depth and thickness of bottom barrier
99
-------
• construction method for perimeter barrier
• required spacing of injection holes
Data
None available.
3.2.5 Groundwater Pumping
3.2.5.1 Description
Groundwater pumping uses a series of wells to remove groundwa-
ter for treatment (if it is contaminated), subsequent discharge, or
both. A well system utilizes one or more pumps to draw groundwater
to the surface forming a cone of depression in the groundwater
table, the extent and slope of which is dependent on pumping rates
and duration as well as local groundwater and soil factors.
Groundwater pumping can be used to lower the water table and to
contain a plume. It can also be utilized in conjunction with other
groundwater controls (impermeable barriers or subsurface drainage
systems) to maximize their efficiency. Although pumping can be
expensive compared to other control technologies, it might be the
most practical alternative under certain circumstances, including
(Doering and Benz, 1972) :
• combinations of fine and textured soils or upward hydraulic
gradients make subsurface drainage difficult; and
• groundwater conditions are stagnant e.g., hydraulic gradi-
ent is nearly zero.
3.2.5.2 Status
Conventional, demonstrated.
3.2.5.3 Feasibility and Effectiveness
100
-------
Drawdown
The effective drawdown (s) of a well or well system can be very
difficult to estimate. The following equations are used to estimate
drawdown under certain conditions (Freeze and Cherry, 1979):
• In a confined, isotropic aquifer:
^^T.T
W(u)
In an unconfined aquifer at early time (t < a few minutes) :
• In an unconfined aquifer at later time (t <>a few minutes)
where:
r2S
u = UA = 4ft
u = r2Sy
B 4Tt
r2
n = — in an xsotropic aquifer
b2
r2kl
n = —2— in an anise-tropic acquifer
b k2
and:
Qw = pumping rate of the well
T = transmissivity of the aquifer
W(u) = well function for confined aquifers
W(UA,H) = type A well function
W(u ,n) = type B well function
101
-------
r = radial distance from the well where
drawdown is measured
t = time from initial pumping at which
drawdown is measured
S = storativity of the aquifer
Sy = specific yield of the aquifer
b = depth of the aquifer before pumping
kl = vertical hydraulic conductivity
k2 = horizontal hydraulic conductivity
Values for W(u) , W(u^,n) and W(u_.,n) can be found in
A o
standard hydrology texts or engineering manuals. For
u<.01, W(u) can be approximated as:
TT/ . T 2.246 T t
W(u) = In
r2 S
The previous equations are based on the following assumptions:
• the aquifer is homogeneous,
• the aquifer is not leaky,
• the well penetrates and is screened over the entire depth of
the aquifer,
• pumping rate is uniform over time,
• only one aquifer is affected by the well,
• there are no barriers or rivers within the radius of influ-
ence of the we 11, and
• flow to the well remains saturated for confined aquifers.
For a multiple well system total drawdown at a given place and
time is simply the added drawdown of each individual well such that
(Freeze and Cherry, 1979):
102
-------
n
Stotal = A Swell (i)
1 — 1
Wellpoint System
A wellpoint system is used in shallow, unconfined aquifers. It
consists of a series of riser pipes screened at the bottom and con-
nected to a common header pipe and a centrifugal pump. A typical
wellpoint dewatering system is shown in Figure 3-10.
Wellpoint systems are practical up to 10 meters (33 ft) and most
effective at 4.5 meters (15 ft)(Sommerer and Kitchens, 1980). Their
effectiveness, however, will depend on site-specific conditions.
Spacing of individual wellpoints also depends on site-specific
conditions, particularly the hydraulic conductivity of the aquifer.
Wellpoints should be close enough together so that sufficient draw-
down is maintained between the wells. Typical spacing is 1 to 2
meters (3 - 7ft)(Sommerer and Kitchens, 1980).
Deep Well Systems
Deep well systems can be used in aquifers located at depths up
to several hundred meters.
Construction methods and concerns for deep wells are the same as
those for monitoring wells. Wells must be of sufficient diameter
(at least 10 cm) to house a submersible pump and handle expected flow
(Sommerer and Kitchens, 1980)
Well spacing and location depends on site-specific conditions,
particularly the hydraulic conductivity of the aquifer and adjoint
soils. Wells should be spaced such that sufficient drawdown is
maintained between wells (Sommerer and Kitchens, 1980).
103
-------
FIGURE 3-10
SCHEMATIC OF A WELL POINT DEWATERING SYSTEM
(Source: EPA, 1982)
Water-bearing
stratum
Special Precautions and Limitations
If any of the assumptions listed below the drawdown equation is
not valid for a particular well system, the simple drawdown
equations are not valid. A hydrologist should be consulted to
determine drawdown on a site-specific basis.
The effect of long-term pumping on local groundwater levels
should be considered (Sommerer and Kitchens, 1980). Recharge of the
aquifer may be necessary in some cases to maintain water levels or
conform with state law.
3.2.5.4 Principal Data Requirements
Depth to impermeable strata (effectiveness of pumping)
Soil characteristics (soil suitability to pumping)
104
-------
• grain size distribution
• texture
Groundwater characteristics (effectiveness of pumping)
• depth to water table
• potentiometric surfaces - hydraulic gradient
• recharge quantity
Aquifer characteristics (effectiveness of pumping)
• transmissivity
• storativity
• specific yield
• depth
• type - confined or unconfined
• condition- homogeneous, leaky, isotropic
• extent - limited by barriers or surface water
Regulations concerning maintenance of existing water table
levels.
3.2.5.5 Elements of Cost Review
Components
Construction and Capital--
• well drilling
• pumps
• casing and screening material
• treatment system or recharge basin
105
-------
O & M--
• electricity for pump
• pump maintenance
• monitoring
Major Factors
• number and depth of wells
• casing and screening material
• pump size
• drilling techniques
• treatment or recharge
Data
Unit costs for groundwater pumping wells and a recharge basin are
given in Table 3-9.
Total cost for an 11 meter (36 ft) deep, 22 well system using 22,
4-inch submersible pumps and 8-inch steel piping in 1982 dollars is
$269,000 (EPA, 1982).
3.2.6 Subsurface Drains
3.2.6.1 Description
Subsurface drains are constructed by placing tile or perforated
pipe in a trench, surrounding it with a gravel (or similar material)
envelope, and backfilling with topsoil or clay. Historically they
have been used to dewater agricultural and construction sites. At
an uncontrolled site, subsurface drains can be installed to collect
leachate as well as lower the water table for site dewatering.
106
-------
TABLE 3-9
UNIT COSTS FOR WELL INSTALLATION
Unit
1982 $ Cost
Wells: Construction and
installation without
casing
Casing
4 inch PVC
6 inch PVC
8 inch PVC
4 inch Submersible pump
180 feet; 23gpm
Steel Pipe (8")
Recharge Basins:
Excavating costs
using a backhoe
Hauling; assume one mile
round trip
Retaining Wall using
stone filled gabions
Sand liner ( including
transportation costs)
2.96 - 3.70 per inch
diameter per foot of
depth
5.45/ft
7.87/ft
12.71/ft
1500
53.64/ft
1.82/yd
2.98/yd3
91.96/linear foot
8.47/yd3
Source: EPA, 1982
3.2.6.2 Status
Conventional, demonstrated
3.2.6.3 Feasibility and Effectiveness
Design Flow
Design flow per meter of drain can be determined by performing a
107
-------
water balance to estimate the amount of water a drain will need to be
able to transport (EPA, 1982). Manning's formula can then be used to
determine pipe size (Linsley and Franzini, 1979).
Inflow to a pipe can also be roughly estimated as (Frogge and
Sanders, 1977):
_ DA (k)
g ~ 10
where:
Q = inflow to pipe (m3/sec)
DA = area draine'd by pipe (m2)
k = soil permeability (m/sec)
This should be used as a rule of thumb only.
When a subsurface drainage system involves more than one line of
drains, inflow to the drains downgradient of the first line is typi-
cally assumed to be 75 percent of that of the first line (Frogge and
Sanders, 1977) .
Drain Spacing
Distance between adjacent drains is primarily a function of
drain depth, design flow (hydraulic capacity) of the drain, and soil
permeability. The equation normally used to determine drain spacing
is (Linsley and Franzini, 1979):
T _ 4k (b2 - a2)
•L" — ZZ
where •.
L = distance between adjacent drains (m)
k = soil permeability (m/sec)
Q = design flow per meter of drain (m3/sec/m of
drain)
108
-------
a = height of drain above impermeable barrier (m)
b = maximum height of water table above impermeable
barrier (m)
See Figure 3-11.
This equation assumes steady-state, one-dimensional flow
through homogeneous soil. If these assumptions are not valid, spac-
ing may be determined experimentally based on soil properties.
Determining spacing based on two or three dimensional flow becomes a
differential boundary value problem based on Laplace's equation.
This can be solved using computer generated or published solutions
(EPA, 1982).
Drain Depth
Drain depth is determined based on site-specific conditions.'
In general, the deeper the drain, the wider the spacing that is pos-
sible (and, therefore, the fewer drains that are required).
However, cost of deeper drains with larger design flow should be
compared with shallower drain with smaller design flow to determine
the optimal number and depth of drains.
Construction
An envelope of permeable material (typically gravel) should
surround the drain pipe. Recommended minimum thickness of the drain
envelope is 8 to 10 cm (3 to 4 in) (EPA, 1982). A typical envelope
thickness is 14 cm (6 in) and can be much larger. For example, at the
Love Canal the gravel envelope was about 66 cm thick (26 in.) . The
envelope of permeable material may be wrapped with a fabric to pre-
vent clogging with soil (EPA, 1982).
Drain slopes should be sufficient to prevent the settling of
suspended solids. Minimum recommended slopes for three pipe diam-
eters are (EPA, 1982):
Diameter (cm) Grade (%)
10 .10
12.5 .07
15 .05
109
-------
FIGURE 3-11
SPACING EQUATION DIAGRAM
(After: Frogge and Sanders, 197?)
Ground Surface
-, >/*•"••.> ~
-------
corrosive or high strength chemical wastes than plastic or metal
pipe (EPA, 1982) .
3.2.6.4 Principal Data Requirements
Depth to impermeable strata (drain spacing)
Soil permeability (drain spacing and pipe inflow)
Depth to water table (drain spacing)
Groundwater and leachate chemistry (pipe material
selection)
Drainage area of pipes (inflow to pipe)
3.2.6.5 Elements of Cost Review
Components
Construction and Capital--
• trench excavation
• envelope material
• backfill material
• drain material
• pumps
O & M--
• electricity for pumping
• monitoring and analysis
111
-------
TABLE 3-10
UNIT COSTS FOR A SUBSURFACE DRAINAGE SYSTEM
Item
1982 Unit Cost
Excavation;
20 ft. deep, 4 ft. wide;
hydraulic backhoe
Crushed stone; 3/4 inch
Cost to buy, load, haul
2 miles, place, and spread
Tile Drainage
Vitrified clay (Standard bell
and spigot)
4" perforated
6" perforated
8" perforated
Precast concrete manholes
48" x 3'
48" x 4'
Concrete wetwells
Sewer piping;
Concrete; nonreinforced;
extra strength
6" diameter
8" diameter
Bituminous fiber
4" diameter
Sewer piping; PVC
4"
6"
Backfilling:
Spread dumped material
by dozer
$ 1.27/yd'
$ 10.54/yd-
$ 2.73/LF installed
$ 3.34/LF installed
$ 5.50/LF installed
$229.35
$273.98
$8,300
$ 5.00/LF
$ 5.47/LF
$ 2.58/LF
$ 2.11/LF
$ 3.50/LF
$ 5.58/LF
$ .84/yd"
LF = linear foot
112
-------
TABLE 3-10
UNIT COSTS FOR A SUBSURFACE DRAINAGE SYSTEM (Cont.)
Item 1982 Unit Cost
4" Submersible pumps
installed; to 180 ft.
2 HP; 840-1440GPH $ 2,100
5 HP; 1302 - 1494 GPH; $ 2,900
Holding tank;
Horizontal cylindrical glass
fiber reinforcement phthalic
risen tanks
10,000 gal $ 7,700 installed
20,000 gal $ 17,100 installed
Portland cement grout $ 1.10/gallon
Bentonite grout $ 1.40/gallon
Source: EPA, 1982
Major Factors
• number, size, and depth of drains
• number and size of pumps
Data
Unit costs for a subsurface drainage system are given in Table
3-10.
Total cost for a drain system 260 meters (850 ft) long and 6
meters (20 ft) deep using 4-inch cement pipe and one submersible
pump, in 1982 dollars, is $32,500 to 43,800. 0 & M accounts for
approximately one-third of total costs, primarily due to sample col-
lection and analysis (SCS, 1980).
113
-------
3.3 SURFACE WATER CONTROL TECHNOLOGIES
3.3.1 Dikes
3.3.1.1 Description
Dikes are compacted earthen ridges designed to divert or retain
surface water flow. They can be used to control floodwater or to
control runoff.
Flood control dikes (or levees) are divided into three classes.
These are described in Table 3-11.
Runoff control dikes are divided into two groups:
• interceptor dikes which are built with a 0% grade and are
designed only to reduce slope length; and
• diversion dikes which are built with a grade sufficient to
drain and are designed to intercept and divert surface flow
as well as reduce slope length.
3.3.1.2 Status
Conventional, demonstrated.
3.3.1.3 Feasibility and Effectiveness(SCS, 1973)
Flood Control Dikes
Information in this part is from SCS 1973, unless otherwise not-
ed.
Height— Design height, H, of a dike is given by:
114
-------
TABLE 3-11
DIKE CLASSIFICATION
Class
Class I
Class II
Site Conditions
•Maximum protection against
flooding is required
•Water levels ^4 meters above
normal ground level are
expected
•Moderate protection required
•Water levels ^4 meters above
normal ground level are
expected
Class III 'Minimum protection required
•Water levels <2 meters for
mineral soils and <1.3 meters
for organic soils are
expected
Design Requirements
•Design height equals depth of
record, 100 year, or 50 year
flood, plus wave allowance in
excess of 60 cm (2 ft)
•Cross section design based on
wave action, site exposure and
soil stability analysis
•Stable mineral soil required
in foundation and embankment
•Design height equals depth of
25 year flood or greater.
A less stringent design may
be used if fuse plug sections
or other relief measures are
included in the design
•Cross section design based on
design water height
•Design based on SCS state
standards for specific site
condition
Based on Engineering Standards for Dikes - Code 356, SCS, National
Engineering Handbook
Source: SCS, 1973
H = Hw + Hv + Hs if Hv > Hf; or
H = Hw + Hf + Hs if Hf > Hv.
where:
Hw = design high water stage
Hv = additional height for wave action
Hf = additional height for freeboard
The constructed height of a dike is
H + Hs, where Hs is an allowance for
settlement.
115
-------
FIGURE 3-12
TYPICAL DIKE CROSS SECTION
(Source: SCS, 1973)
CONSTRUCTED TOP
SETTLED TOP
HIGH
WATER
LEVEL
•MKF-. ~K~_'. - H
These are shown in Figure 3-12.
Wave height allowance is based on:
• wind velocity and duration,
• fetch;
• angle of wave action,
• Hw, and
• length of dike.
Minimum allowance for freeboard is .6 meters (2 ft)
Settlement allowance depends on:
116
-------
• dike materials
• construction methods.
General rules of thumb for Hs include:
• Hs > 5% H if dike is compacted by heavy
equipment
• Hs > 10% H if dumped fill is placed and
~" shaped
• Hs>40% H if soil is unusually high in
organic matter
Top width-- Recommended top widths are given in Table
3-12.
Side slopes-- Recommended side slopes are given in Table
3-13.
Construction-- Suitability of various soils for use in
dike construction is given in Table 3-14. Table 3-14 also indicates
which soils may require the construction of core trenches to elimi-
nate seepage under Class I and Class II dikes.
A banquette or constructed berm should protect the land side toe
of the dike if the structure crosses an old channel, has excessively
porous fill, or has poor foundation conditions. Banquette width
should be greater than dike height and should be more than 30 cm (1
ft) above ground level.
Class I and II dikes may require foundation and toe drains to
control excess seepage and backwater flow.
Dike route should meet the following conditions:
• follow the shortest economically feasible path consistent
with protecting the site;
• avoid natural physical hazards, such as sloughs or eroding
slopes;
117
-------
TABLE 3-12
RECOMMENDED DIKE TOP WIDTHS3
Class
I
I
II, III
II, III
III
Dike Height (m)
> 5
< 5.
> 2
< 2
< 1.3
Soil
Mineral
Mineral
Mineral
Mineral
Organic
Width (m)
3.9
3.3
2.6
2.0
2.6
aEquipment width (3.3 meters) required if top is used as a maintanance
road
Source: SCS, 1973
• attempt to use natural protection against waves, such as
areas of trees or brush;
• border public roads and property lines where possible to
allow easy access and property easement; and
• utilize natural storage basins where possible.
Fill material for levees should be taken from borrow pits within
the floodplain where possible to provide alternative storage volume
for floodwaters.
Runoff Control Dikes (EPA, 1976, Vol. 2)
Design requirements for runoff control dikes may vary according
to state regulations. No formal design plan is required for these
dikes. Typical requirements are given in Table 3-15.
Spacing of interceptor dikes depends on slope of the area above
the dike:
118
-------
TABLE 3-13
RECOMMENDED DIKE SIDE SLOPES
Maximum
Dike Description Slope
Class I; (stability analysis should be 4:1
performed to determine exact slope)
Class II, III; water depths < 2 m, 1.5:1
compacted fill
Class II,III; water depths < 2 m, 2:1
fill not compacted
Class II,III; water depths 2 to 4 m, 2:1
compacted fill
Class II, III; water depths 2 to 4 m, 2.5:1
fill not compacted
Soil has low plasticity, or significant 3:1
wave action or frequent, rapid
drawdown is expected
Source: SCS, 1973
119
-------
TABLE 3-14
SOIL CHARACTERISTICS
j Coarse-grained soils - (Less than 50% passing #200 sieve)
Group
Symbol
GW
GP
GM
GC
SW
SP
SM
sc
Soil Description
Well graded gravel and gravel-
sand mixtures. Little or no
fines.
Poorly graded gravels and
gravel-sand mixtures. Little
or no fines.
Silty gravels and gravel-sand-
clay mixtures.
Clayey gravels and gravel-
sand-clay mixtures.
Well graded sands and gravelly
sands. Little or no fines.
Poorly graded sands and
gravelly sands. Little or
no fines .
Silty sands and sand-silt
mixtures.
Clayey sands and sand-clay
mixtures
Suitability - Dikes
Very stable - suited for shell of
dike. Good foundation bearing.
Stable - suitable for shell of
dike. Good foundation bearing.
Stable - generally adequate for
all stages. Good foundation
bearing. Good compaction with
rubber tires.
Stable - adequate for all stages.
Good foundation bearing. Good
compaction with rubber tires.
Very stable - adequate for low
stages. Good foundation bearing.
Compaction good with crawler
tractor.
Stable - adequate for low stages.
Generally fair foundation bearing.
Use flat slopes and wide berms.
Compaction good with crawler
tractor.
Fairly stable - adequate for low
stages. Only fair foundation
bearing. Use wide berms. Good
compaction with rubber tires.
Stable - adequate for all stages.
Generally good foundation bearing.
Fair compaction with rubber tires.
Permeability
and Slopes
Rapid - will need core.
Rapid - may not need core
for lower stages of short
duration.
Moderate - may not need
core except for long flood
duration.
Slow permeability
Rapid - may need core for
high stages of long
duration.
Rapid - will need core for
long duration. Use flat
slopes. Protect against
wave action.
Moderate - use flat slope
on water side. Protect
against wave action.
Slow -
-------
TABLE 3-14
SOIL CHARACTERISTICS (Cont.)
Fine-grained soils - (More than 50% passing #200 sieve) fj
Group
Symbol
ML
CL
OL
MH
CH
OH
Pt
Soil Description
Inorganic silts and very fine
sands, rock flour, silty or
clayey fine' sands and clayey
silts of slight plasticity.
Inorganic clays of low to
medium plasticity, gravelly
clays, sandy clays, silty
clays and lean clays.
Organic silts and organic
clays having low plasticity.
Inorganic silts, micaceous or
diatomaceous fine sandy or
silty soils and elastic silts.
Inorganic clays having high
plasticity and fat clays.
Organic clays having medium
to high plasticity and
organic silts.
Peat and other highly organic
soils.
Suitability - Dikes
Poor stability - generally adequate
for low stages. Fair foundation
bearing. Dumped fill on Class III
dikes only. Fair compaction with
rubber tires.
Stable - adequate for all stages.
Fair foundation bearing. Fair
compaction with rubber tires. Use
dumped fill on lower stages only.
Very poor stability - may be
adequate for Class III dikes of
low height. Can use dumped fill.
Low stability - generally adequate
for all stages. Difficult to
compact. Could use dumped fill
for low stages. Poor foundation
bearing.
Fairly stable - adequate for all
stages. Poor compaction, dumped
fill may be adequate.
Very low stability - Adequate only
for low stages and can use dumped
fill. Has poor foundation bearing
and compaction.
Very low stability - use only for
temporary dikes. Remove from foun-
dation for mineral soil dikes.
Permeability
and Slopes
Moderate - use flat slope
on water side. Protect
slopes against erosion
forces.
Slow -
|
Moderate - use for very
low stage only. Slopes at
natural angle of repose
when we t . ;
Slow - use flat slopes and
protect against erosion.
Very slow permeability.
Use flat slopes on water ;
side.
Very slow - use for low
stages only. Use flat
slopes.
Variable - may vary
significantly between
vertical and horizontal.
Note: This table based on the Unified Classification System and field experience.
Rubber tires refer to rubber tired equipment.
_,
Source: SCS, 1973
-------
TABLE 3-15
RUNOFF DIKE REQUIREMENTS
Parameter
Typical
Requirement
Comments
Height
Top width
Side slope
Drainage area
Design life
Grade
Stabilization
.45 meters minimum
.6 meters minimum
2:1 (50%) or flatter
4 2
2x10 m (5 acre) maximum
1 year
Should be positive
Required if slope is
over 5%
9 cm freeboard required
if used as a diversion
1.2 meters if used as
a diversion
Can be extended if
stabilized and well
maintained
Source: EPA, 1976 Vol. 2
Slope
5-10%
< 5%
Distance Between Dikes
45m (150 ft )
60m (200 ft )
90m (300 ft )
Special Precautions and Limitations
None.
3.3.1.4 Principal Data Requirements
122
-------
Flood Control Dikes
Topography (construction and route)
Accessibility of suitable construction material (cost,
implementability)
Depth to low-permeability stratum or bedrock (depth of sub-
surface cutoff)
Soil characteristics (construction and dike stability)
• organic content
• strength properties
• erosion potential (see discussion of erosion con-
trol in Section 2)
Wind characteristics (dike height)
• velocity
• duration
Flood characteristics (dike height, class required)
• height of design flood
• wave angle and fetch
• limits of flood stages
• duration
Runoff Control Dikes
Topography (dike placement)
Soil erosion potential (dike placement and stability) (see
discussion of erosion control in Section 2)
Storm characteristics (dike stability, lifetime)
Runoff quantity and depth (dike height, stability)
Drainage area (dike placement, number required)
123
-------
State regulation (design requirements)
3.3.1.5 Elements of Cost Review
Components
Construction and Capital--
• soil required
• impermeable core and cutoff
• equipment
• transportation
• drainage
0 & M--
• Maintenance
Major Factors
• dike purpose (flood or runoff control, class)
• number, size and length of dikes
• equipment and material required
Data
Unit costs associated with dikes are given in Table 3-16.
3.3.2 Terraces
3.3.2.1 Description
Terraces are embankments or combinations of embankments and
124
-------
TABLE 3-16
UNIT COSTS ASSOCIATED WITH SURFACE WATER DIVERSION AND COLLECTION STRUCTURES
Unit Operation 1982 Unit Cost
Excavation, hauling,
grading (spreading and
compaction) -
1,000 - 5,000 haul $ 1.13 - 2.52/yd^
2 miles $ 2.16 - 2.47/yd
Grading site excavation
and fill (no compaction) „
75 h.p. dozer 300' haul $ 2.78/yd^
300 h.p. dozer 300' haul $ 1.85/yd
Trench Excavation ~
clay hauling $ 9.89/yd
spreading
compaction «
sand hauling $ 17.51/yd
spreading
compaction
Loam, sand and loose gravel o
1' - 6' deep; %:1 sides $ .50 - .85 /yd-
6' - 10' deep $ .50 - .66/yd
Compacted gravel and till o
1' - 6' deep; %:1 sides $ .50 - .88/yd3
6' - 10' deep $ .38 - .62 /yd
Building embankments;
spreading, shaping, compacting; ^
material delivered by scraper $ . 24 - .48/yd,,
material delivered by back $ .57 - .80 /yd
dump
Placement of ditch liner
pipe; 1/3 section
15" .radius $ 12.19 /ft
18" radius $ 18.67 /ft
24" radius $ 23.37 /ft
o
Loose gravel, excavate, $ 5.15 - 5.67/yd
load, haul 5 miles
spread, compact
3
Stone riprap; dumped $ 21.12 /yd
from trucks, machine
placed
125
-------
TABLE 3-16
UNIT COSTS ASSOCIATED WITH SURFACE WATER DIVERSION AND COLLECTION STRUCTURES
-———-(Cont.)
Unit Operation
1982 Unit Cost
Soil testing
liquid and plastic
hydrometer analysis;
specific gravity
moisture content
permeability
proctor compaction
shear tests, trioxical
direct shear
Level spreader construction
Corrugated galvanized
steel underdrain pipe,
asphalt-coated, perforated;
12" diameter, 16 gage
18" diameter, 16 gage
Corrugated galvanized
metal pipe, with paved
invert;
18" diameter, 14 gage
36" diameter, 12 gage
48" diameter, 12 gage
Steel sheet piling;
15' deep, 22 psf
20' deep, 27 psf
25' deep, 38 psf
Backflow preventer;
gate valves, automatic
operation, flanged;
10" diameter
$44.50/test
$76.28/test
$10.59/test
$63.57/test
$50.85 - 57.21/test
$243 - 444/test
$90.00 - 286/test
$ 4.53 - 9.06/ft
$15.24
$21.59
$25.08/ft
$63.55/ft
$84.84/ft
$10.35/ft2
$12.07/ft
$15.49/ft2
$11.30 each
Sump pumps;
6" - 12" centrifugal
pumps, operating 1
shift/day
$229 - 332/day
126
-------
TABLE 3-16
UNIT COSTS ASSOCIATED WITH SURFACE WATER DIVERSION AND COLLECTION STRUCTURES
-(Cont.i
Unit Operation
1982 Unit Cost
Temporary sediment basin
construction;
drainage area, 1-25 acres
50-75 acres
75-100 acres
100-125 acres
Sediment removal from basins
Paved flume, installed
:? 560 - 3,020 each
$ 5,670 - 9,450 each
$ 9,450 - 12,100 each
$12,100 - 15,120 each
$ 5.67 - 13.23/yd3
$ 37.80 - 56.70yd2
Source: EPA, 1982
channels constructed across a slope (EPA, 1976, Vol. 1). As seen in
Figure 3-13, a variety of terrace cross sections are possible
depending on slope and site-specific requirements. Terraces can be
used to:
• intercept and divert surface flow away from a site; and
• control erosion by reducing slope length.
3.3.2.2 Status
Conventional, demonstrated.
3.3.2.3 Feasibility and Effectiveness
Spacing
If data are sufficient, slope length can be determined using the
universal soil loss equation. The equation is (TRD 8) :
127
-------
FIGURE 3-13
TYPICAL TERRACE CROSS SECTIONS
(Source: ASAE, 1978)
Used by permission, see Copyright Notice
ORIGINAL
GROUND SURFACE
05MI1 5FTI
CUT SLOP€
FRONT SLOPE
BACK SLOPt
BROADBASE TERRACE CROSS SECTION
ORIGINAL
GROUND SURFACE
0.5Mil 5FT)
FLAT CHANNEL TERRACE OR ZINGG CONSERVATION
BENCH TERRACE CROSS SECTION
OO
ORIGINAL
• GROUND SURFACE
05MI1 5FTI
MAX 2:1 SLOPE,
SHOULD IE GRASSED
0.2 PERCENT
MIN SLOPE
STEEP-BACKSLOPE TERRACE CROSS SECTION
ORIGINAL
GROUND SURFACE
05MI1 5FT)
MAX 2:1 SLOPE
MAX 4-1
SLOPE
05M1I 5FTI
NARROW-BASE TERRACE CROSS SECTION. Slopes are
the maximum allowable and should be grassed.
ORIGINAL
GROUND SURFACE
_J L_ 06MI20FTI
2.1 SLOPE
ORIGINAL
GROUND SURFACE
05MI1 5 FT)
BENCH TERRACE CROSS SECTION
RIDGELESS CHANNEL TERRACE CROSS SECTION
-------
A = RKLSCP
where:
A = maximum allowable soil loss
R = rainfall and runoff erosivity index
K = soil credibility factor
L = slope length
S = slope steepness
C = cover/management factor
P = practice factor
Solving for SL, the horizontal interval (HI) between terraces
is found by (SCS, 1973)
100SL
HI =
0.76 + 0.53S' + 0.076S'2
Where: S' is the land slope in percent
The Universal Soil Loss Equation is discussed in detail in TRD
8.
Alternatively, the allowable vertical distance between adja-
cent terraces, called the vertical interval (VI), is given by (ASAE,
1978):
VI = XS + Y
where:
VI = vertical interval in meters
X = geographic constant given in Figure 3-14
S = average slope of the land draining on
to the terrace
129
-------
FIGURE 3-14
VALUES OF X IN EQUATION VI = XS+Y
(Source: Sommerer and Kitchens, 1980)
-------
Y = constant valued at .3, .6, .9, or 1.2
based on soil erodibility and land use.
Low values of y are appropriate for
very erodible soils, and high values
for erosion resistant soils.
This provides an estimate that can be varied up to 25 percent in
the field without serious danger of failure (TRD 8) .
Cross Section
Terrace cross section dimensions (width = w, and height = h),
are a function of capacity, slope, length, roughness coefficient
(Manning's n) and soil erodibility. Combining Manning's formula and
the flow equation:
Ar
2/3 _
Qn
where:
Q = design capacity (m3/sec.) Usually the peak
runoff is from the 24-hour, 10-year
frequency storm (Rochester and Busch,1974).
However, larger capacities may be required
depending on the consequences of terraces
failure.
n = Manning roughness coefficient. ASAE recom-
mends using .06 as an estimated value.
Cm = dimensionless. (i.o when using metric units)
S = slope or terrace grade (m/m). Depends on
terrace length and soil erodibility. Maximum
grades are given in Table 3-17.
A = cross-section area.
r = hydraulic radius (area divided by wetted
perimeter, (w x h)/(w + 2h), in m).
131
-------
TABLE 3-17
MAXIMUM TERRACE GRADES
Slope (per cent)
Terrace length (m)
or length from upper Erosive soil Resistant soil
end of long terraces (Silt loam) (Gravelly or Rocky)
153
153
61
31
or
or
or
or
more
less
less
less
0
0
1
2
.35
.50
.00
.00
0
0
1
2
.50
.65
.50
.50
Source: TRD 8
Determination of the relationship between height and width
depends on slope and other site-specific conditions. Height should
allow for settlement, channel sediment deposits, ridge erosion, and
a safety factor. Ridge and channel should have a minimum, total
width of 0.9 meters (3 ft) (ASAE, 1978).
There are no general rules for determing type of cross section
used. However, as field slope increases, ridge height (or channel
depth), terrace width and grade should also increase. Some details,
particular to a given cross section, are shown in Figure 3-13.
Length
Maximumm recommended terrace length is 300 to 350 meters (980 to
1,150 ft) (TRD 8) .
Drainage
Terraces should be designed so that they drain in a maximum of
48 hours.
132
TT
-------
Graded or open-ended terraces use vegetated outlets.
Closed-end or level terraces use underground outlets (underground
conduit with outlet pipe) or soil infiltration.
Special Precautions and Limitations
None.
3.3.2.4 Principal Data Requirements
Topography (spacing and cross section dimensions)
Vegetation (land use, spacing)
Soil erosion potential (spacing, stability)
Infiltration rate (drainage)
Runoff (cross section dimensions)
3.3.2.5 Elements of Cost Review
Components
Construction and Capital--
• equipment
• additional material
• transportation
O & M--
• Maintenance
Major Factors
• number, size and length of terraces
133
-------
• material and equipment availability
Data
Unit costs associated with terraces are given in Table 3-16.
3.3.3 Channels
3.3.3.1 Description
Channels are excavated ditches that are generally wide and
shallow with trapezoidal, triangular, or parabolic cross sections.
Diversion channels are used primarily to intercept runoff or reduce
slope length. They may or may not be stabilized. Channels stabi-
lized with vegetation or stone riprap (waterways) are used to col-
lect and transfer diverted water off site or to on-site storage or
treatment.
3.3.3.2 Status
Conventional, demonstrated.
3.3.3.3 Feasibility and Effectiveness
Design Flow
The Manning formula is considered when designing for steady
uniform flow in open channels:
V = m R2/3 sl/2
n
and for an open channel of cross-sectional area, A
Q = Cm A R2/3 S1/2
n
134
-------
where:
Q = design capacity, m3/sec
R = hydraulic radius (area divided by wetted
perimeter), m
A = cross-sectional area of the channel, m2
S = channel slope, m/m
Cm = dimensionless constant (1.0 for metric units)
n .= Manning roughness factor, sec/m1/3. Values of
n for various materials are given in Table 3-18
Permissible flow velocities for channels lined with vegetation
are given in Table 3-19.
Channel Dimensions
Parabolic cross sections are considered most suitable for use
at disposal sites since they cause the least amount of erosion (TRD
8). Typical channel cross sections are shown in Figure 3-15.
Wetted perimeter (p) for a parabolic channel is given by (TRD
8):
Design requirements for diversion channels may vary according
to state regulations. Typical requirements are given in Table 3-20.
Channel spacing (when used for interception or to reduce slope
length) depends on the slope of the area above the channel (EPA, 1976
Vol. 2).
Slope Distance Between Channels
>10% 30m (100 ft )
5-10% 60m (200 ft )
<5% 90m (300 ft )
135
-------
TABLE 3-18
VALUES OF MANNING'S n FOR VARIOUS CHANNEL SURFACE MATERIALS
MaterialSuggested
n a'b
Planed wood 0.012
Unplaned wood 0.013
Finished concrete 0.012
Unfinished concrete 0.014
Cast iron 0.015
Brick 0.016
Riveted steel 0.018
Corrugated metal 0.022
Rubble 0.025
Earth 0.025
Earth with stones or weeds 0.035
Gravel " 0.029
Vegetation .04 c
aThe Manning formula is an empirical formula. The dimensions
of Cm and n are therefore somewhat arbitrary. In metric
• units, Cm = 1.0 and n is in (s)/(ml/3). In English units,
Cm = 1.486 (ftl/2)/(s) and n is in ftl/6. The numerical values
for n, however, do not change.
In situations with R>3m, roughness factor should be
increased by 10 to 15%.
°From TRD 8.
Source: Streeter and Wylie, 1975
136
-------
(Jj
TABLE 3-19
PERMISSIBLE VELOCITIES FOR CHANNELS LINED WITH VEGETATION
Permissible Velocity (feet/sec)
Erosion resistant soils
(per cent slope)
Cover 0-5 5-10 Over 10
Bermuda grass 87 6
Buffalo grass
Kentucky bluegrass
Smooth brome 76 5
Blue grama
Tall fescue
Easily eroded
(per cent
0-5 5-10
6 5
5 4
soils
slope)
Over 10
4
3
Lespedeza serica
Weeping lovegrass
Kudzu
Alfalfa
Crabgrass
3.5
NR£
NR
Not Recommended
Source: TRD 8
2.5
NR
NR
Grass mixture 54 NR
Annuals for
temporary 3.5 NR NR
protection
43 NR
2.5 NR NR
-------
FIGURE 3-15
TYPICAL CHANNEL CROSS SECTIONS
(After: TRD #8)
D d
1
T
t
Trapezoidal Channel
n
•"I
i
D
1
Tt te.
t
d
T „ fllh%fti>naC8,i
NaraaBy
Rectangular Channel with Stone Center
Triangular Channel
Legend:
T = Total Construction Top Width
t = Design Top Width of Water Flow
D = Total Construction Depth
d = Design Depth of Flow
Parabolic Channel
138
-------
TABLE 3-20
TYPICAL CHANNEL DESIGN REQUIREMENTS
Parameter Typical Requirement
Depth .3 meters (1 foot) minimum
Bottom width 2 meters (7 feet) minimum
Side slope 2:1 (50%) or flatter
4 2
Drainage area 2x10 m (5 acres) maximum
Source: EPA, 1976
Special Precautions and Limitations
For diversion channels, stabilization with vegetation or stone
riprap is required for slopes greater than 5 percent and may be nec-
essary for slopes less than 5 percent, depending on site-specific
conditions (EPA, 1976, Vol. 2).
For channels used as waterways, stabilization is required. If
flow is expected to be continuous i.e., if there is a base flow, the
waterway should have a stone center, as shown in Figure 3-15.
3.3.3.4 Principal Data Requirements
Topography (capacity, placement, stabilization)
Soil erosion potential (stabilization required)
Storm characteristics (stability, lifetime)
Drainage area (placement)
State regulations (design requirements)
3.3.3.5 Elements of Cost Review
Components
139
-------
Construction and Capital--
• channel excavation
• stabilization
0 & M~
• Maintenance
Major Factors
• number, size and length of channels
• stabilization required.
Data
Unit costs associated with channels are given in Table 3-16.
3.3.4 Chutes and Downpipes
3.3.4.1 Description
Chutes (or flumes) are open channels normally lined with bitu-
minous concrete, Portland cement, concrete, grouted riprap, or sim-
ilar nonerodible material.
Downpipes (or downdrains) are drainage pipes constructed of
rigid piping (such as corrugated metal) or flexible tubing of heavy
duty fabric. They are installed with prefabricated entrance sec-
tions. Downpipes can also be open structures constructed by joining
half sections of bituminous fiber or concrete pipe.
Chutes and downpipes are useful in transferring concentrated
flows of surface runoff from one level of a site to a lower level
without erosive damage. Downpipes generally extend downslope from
earthen embankments and convey water to stabilized waterways or out-
lets located at the base of the slope. They are particularly useful
140
-------
in emergency situations since they can be quickly constructed during
severe storms to handle excess flow when downslope waterways over-
flow and threaten the containment of hazardous waste (EPA, 1982).
3.3.4.2 Status
Conventional, demonstrated.
3.3.4.3 Feasibility and Effectiveness
Chutes
Typical design considerations for chutes are given in Figure
3-16.
Chute linings should be well-compacted and smooth, it should be
placed by beginning at the lower end and proceeding upslope.
Chutes should be placed on undistributed soil or well-compacted
fill.
Bottom width and drainage area are based on chute size group as
given in Table 3-21.
Downpipes
Typical design considerations for downpipes are given in Figure
3-17.
Drainage area based on pipe diameter is given in Table 3-22
Special Precautions and Limitations
None.
141
-------
FIGURE 3-16
PAVED CHUTE3
(Source: EPA, 1976, Vol. 2)
Top of earth dike &
top of lining
Undisturbed soil or
compacted fill
Slope varies, not
steeper than 1.5:1
& not flatter than
20:1
Dimen-
sron
u
nmin
dmin
L-min
Size Group
A
1.5'
8"
5'
B
2.0'
10"
6'
Profile
L
2'
2'
r
Place 3" layer of sand
for drainage under outlet as show
19" mi
mm.
for full width of structure
• — Min slope
1/4" per ft
t
D
I
Riprap is 9" layer of
6" min. rock or rubble
I <&>° ° 9* ° ''
• jy • ......^ y—
Toe of slope
Plan view
Requirements for chute designs vary according
to state regulations. Values given are typical.
2 1/2" min.
Section B-B.
142
-------
TABLE 3-21
CHUTE BOTTOM WIDTH AND DRAINAGE AREA
o
Size Group
A-2
A-4
B-4
A-6
B-6
A-8
B-8
A-10
B-10
B-12
Bottom Width b, m
meters (feet)
.07
.14
.14
.21
.21
.28
.28
.35
.35
.42
(2 ft )
(4)
(4)
(6)
(6)
(8)
(8)
(10)
(10)
(12)
Maximum Drainage
Area (x 104m2) b
Units (acres)
2.0
3.2
5.7
4.4
8.1
5.7
10.1
7.3
12.5
14.6
(5 acres)
(8)
(14)
(11)
(20)
(14)
(25)
(18)
(31)
(36)
aFor size group characteristics, see Figure 3^15.
If 75% of drainage area has good vegetative cover (established
grasses and/or shrubs) throughout the design life of the chute,
maximum drainage area may be increased by 50%.
If 75% has a mulch cover throughout the structure's life,
maximum drainage area may be increased by 25%.
Source: After EPA, 1976, Vol. Z
3.3.4.4 PrineipaHData Requi rements
Topography (placement)
Soil erosion potential (placement)
Storm characteristics (capacity)
Runoff (capacity)
Drainage area (capacity)
State regulations (design requirements)
143
-------
FIGURE 3-17
DOWNPIPEa
(Source: EPA, 1976. Vol. 2)
Discharge into a
stabilized watercourse, ^.<^^'"'-i'''''''''<^!^^frlh
sediment trapping device, /if*^.#':>'$fl Ilk
nr r>ntr> ctaKiliToH oroo *>.iV/r.'-jv-'?*J*li'-' ''/.'M H'1 5k
or onto stabilized
Cutaway used
to show inlet
Earth dike
Length as necessary to go
thru dike
2:1
Profile
4' min.
@ less than 1% slope
Standard flared
entrance section
6" min.
cutoff
wall
6D
ii %•!'-•-/•
j I C r •
' »'.!5I
C 5 '
jo:
Riprap shall consist of 6"
diameter stone placed as shown.
Depth of apron shall equal the pipe
diameter and riprap shall be a min-
imum of 12" in thickness.
Riprap apron plan
Requirements for downpipe design vary according
to state regulations. Values given are typical.
144
-------
TABLE 3-22
DOWNPIPE DIAMETER AND DRAINAGE AREA
Pipe Diameter Maximum Drainage Area (xlCTm2)
,. , N Hectares (acres)
meters finches)
,31m (12 inches) .2 hectares (.5 acres)
.46 (18) .6 (1.5)
.53 (21) 1.0 (2.5)
.61 (24) 1.4 (3.5)
.76 (30) 2.0 (5.0)
Source; EPA, 1976, Vol. 2
/
3.3.4.5 Elements of Cost Review
Components
Construction and Capital--
• Channel lining material
• pipe section
• entrance and outlet sections
O & M—
• Inspection and maintenance
Major Factors
• length and size of chute or drainpipe
• construction difficulties.
145
-------
Data
Unit costs associated with chutes and downpipes are given in Table
3-16.
3.3.5 Grading
3.3.5.1 Description
Grading is the general term for technologies used to modify the
natural topography and runoff characteristics of a waste site.
Grading primarily involves the use of heavy equipment (such as doz-
ers, loaders, scrapers and compactors) to spread and compact loose
soil, roughen and loosen compacted soil, and modify the surface gra-
dient. There are six basic grading techniques described in Table
3-23.
3.3.5.2 Status
Conventional, demonstrated.
3.3.5.3 Feasibility and Effectiveness
Applicability
Grading has two primary applications:
1. Slope grade construction. Excavation, spreading, com-
paction, and hauling are used to optimize the slope at a
waste site such that surface runoff increases and infil-
tration and ponding decrease without significantly
increasing erosion. This is of primary importance in the
construction of surface seals and other waste covers.
2. Preparation for revegetation. Roughening techniques
(scarification, tracking and contour furrowing) are used to
reduce runoff, thereby increasing infiltration, and make
the soil receptive to seed or seedlings. This is an impor-
tant aspect of on-site revegetation once an effective sur-
face seal has been applied. These techniques can also be
used off site in conjunction with surface water diversion
technologies to control runon, as seen in Figure 3-18.
146
-------
TABLE 3-23
GRADING TECHNIQUES
Technique
Description
Use
Equipment
Excavation
Spreading
Compaction
Scarification
Tracking
Contour Furrowing
soil removal
soil application
smoothing
compacts soil
increases density
roughening technique
loosens soil
roughening technique
grooves soil along contour
roughening technique
creates small depressions
in soil along contour
slope grade construction
slope grade construction
slope grade construction
dozer, loader, scraper
dozer, loader, grader
dozer, loader, compactor
preparation for revegetation dozer, tractor, harrow
increases infiltration
preparation for revegetation cleated crawler tractor
increases infilrration
preparation for revegetation dozer
increases infiltration
-------
FIGURE 3-18
SURFACE WATER CONTROLS UPSLOPE OF WASTE SITE
(Source: EPA, 1976, Vol. 1)
Diversion and Haul
Road
Tracking
Perimeter dike
Vegetative buffer
Compaction
Compaction is one of the most important grading technique. Com-
paction can be accomplished by (Marek, 1977):
rolling,
impact with heavy object,
vibration, and
loading with static weight.
148
-------
Characteristics of various types of compaction equipment are given
in Table 3-24.
Degree of compaction can be determined by taking a soil sample,
drying it, and filling the hole with sand of known density by the
following equations (Marek, 1977):
V = Ws/Ds
100 (Wm - Wd)
Wd
Dm =
urn
, 100 Dm
c = 100 Dd
Dmax
where:
V = volume of the soil sample, m3
M = moisture content of soil, %
Ws - weight of sand filling hole, kg
Wm = weight of the moist soil, kg
Wd = weight of the dry soil, kg
Ds = density of sand, kg/m3
Dm = density of the moist soil, kg/m3
Dd = density of the dry soil (or dry density) kg/m3
Dmax = maximum theoretical dry soil density, kg/m3
C = compaction, %
Rate of.compaction using rollers can be determined by (Merritt,
1976):
149
-------
Ol
o
TABLE 3-24
COMPACTION EQUIPMENT
Compactor Type
Steel tandem
2-3 axle
Grid and tamping
rollers
Pneumatic small
tire
Pneumatic large
tire
Sheepsfoot
Vibratory
Combinations
aDensity diminishes
Soil Best Suited for
Sandy silts, most granular materials,
some clay binder
Clays, gravels, silts with clay binder
Sandy silts, sandy clays, gravelly
sands and clays , few fines
All (if economical)
Clays, clay silts, silty clays, gravels
with clay binder
Sands, sandy silts, silty sands
All
with depth
Max. Effect
in Loose
Lift, in.
4-8
7-12
4-8
To 24
7-12
3-6
3-6
Density
Gained in
Lift0
Average
Nearly
uniform
Uniform to
average
Average
Nearly
uniform
Uniform
Uniform
Max.
Weight,
Tons
16
20
12
50
20
30
20
Source: Marek, 1977
-------
Rate of compaction, m3/hr = -—
where:
W = width of roller, m
S = roller speed, m/sec
L = lift thickness, cm
F = % reduction in volume due to compaction
E = operator efficiency factor: .90 = excellent;
.80 = average; .75 = poor.
P = number of passes made.
Speed of rollers commonly used are:
sheepsfoot rollers, 1.4 m/sec (3.1 mph) ;
pneumatic rollers, 3.8 m/sec (8.5 mph);
tamping rollers, 4.7 m/sec (10.5 mph); and
grid rollers, 5.7 m/sec (12.8 mph).
Existing cover material should be compacted to a proctor density of
70 to 90 percent of maximum to provide a firm sub-grade (EPA, 1982) .
Recommended slopes are:
• 5 percent minimum to enhance runoff and decrease infil-
tration without risking excessive erosion,
• 6 to 12 percent maximum for top surfaces, and
• 18 percent maximum for side slopes with the center of the
site being the highest elevation (EPA, 1982).
Special Precautions and Limitations
None.
151
-------
3.3.5.4 Principal Data Requirements
Topography (type and extent of grading needed)
Soil characteristics (type grading needed, degree of com-
paction)
• compaction
• erosion potential (see discussion of erosion con-
trol in Section 2).
• moisture content
Storm characteristics (type and extent of grading needed)
Infiltration (type and extent of grading needed)
Runoff (type and extent of grading needed)
Equipment specifications (grading rates)
3.3.5.5 Elements of Cost Review
Components
Construction and Capital--
equipment
material added
hauling
0 & M--
Inspection and maintenance
Major Factors
size of site
152
-------
• type and degree of grading required
• additional material needed
• equipment used
Data
Unit costs associated with grading are given in Table 3-25.
Total costs for grading a 20-acre disposal site requiring 5,650
m^ (7,400 yd^) of new fill in preparation for cover construction, in
1982 dollars, is $96,000 (EPA, 1982).
3.3.6 Surface Seals
3.3.6.1 Description
Surface seals (caps or covers) are impermeable barriers placed
over waste disposal sites to:
• reduce surface water infiltration,
• reduce water erosion,
• reduce wind erosion and fugitive dust emissions,
• contain and control gases and odors, and
• provide a surface for vegetation and other post-closure
uses.
Various impermeable materials may be used including soils and
clays, admixtures, e.g., asphalt concrete, soil cement, and poly-
meric membranes, e.g., rubber and plastic linings.
3.3.6.2 Status
Conventional, undemonstrated. Surface sealing is a standard
technique in the closure of properly designed disposal sites, and
has been used for remedial action. Its effectiveness at uncontrolled
sites, however, has not been determined.
153
-------
TABLE 3-25
UNIT COSTS FOR GRADING
Description 1982 Unit Cost
3
Topsoil (sandy loam), hauling, $15.73/yd
spreading and grading (within
20 miles); labor, materials
and equipment
On-site excavation, hauling,
spreading and compaction of $ 1.19 -2.62/yd
earth (1,000' - 5,000' haul);
labor and equipment
3
Loam Topsoil; material only $ 6.35/yd
3
Excavate, haul 2 miles, ? 2.22 -2.54/yd
spread and compact loam.
sand or loose gravel (with
front end loader); labor
and equipment only
Grading site excavation and
fill (no compaction)
75 h.p. dozer 300' haul $ 2.91/yd
300 h.p. dozer, 300' haul $ 1.96/yd3
Testing soils for compaction $35 or 31/sample
tested
Source: EPA, 1982
154
-------
3.3.6.3 Feasibility and Effectiveness
The design of cover systems is discussed in considerable detail
in Lutton, et. al. , 1979 and in TRD 1. These sources should be con-
sulted if further information is required.
Typical surface seals are composed of several layers,
including:
• barrier layer to restrict the passage of water or gas. The
barrier has low permeability and usually is composed of
clayey soil or a synthetic membrane.
• buffer soil layer above and/or below the barrier layer to
protect the barrier layer from cracking, drying, tearing,
or from being punctured. It is usually a sandy soil.
• filter layer, made of intermediate grain sizes, to prevent
fine particles of the barrier from penetrating and sifting
through the coarser buffer layer.
• gas channeling layer of sand and gravel placed immediately
above the waste to allow generated gases to escape or be
collected. Pipe and trench vents can be used in conjunction
with this layer for gas and odor control.
• top soil layer for growth of vegetation.
Two typical layered cover systems are shown in Figure 3-19. and
the function of each layer is shown in Table 3-26.
The performance of various soils according to surface seal
functions is given in Table 3-27.
The attributes of various chemical additives for cover soils
are given in Table 3-28.
Factors supporting the selection of materials for the impermea-
ble layers are given in Table 3-29.
155
-------
FIGURE 3-19
TYPICAL SURFACE SEALS
(Source: TRD #1)
Loam (for Vegetation)
'///. Clay (Barrier) '////////////
WufcituCi/uUuuuuuuuuu
Gravel (Gas Channel)
oooooooooooooooooo
OOOOOOOOOOOQOOOOOO
oooooooooooooooooo
oooooooooooooooooo
0000000000000000006666660000000000
ooooooooooooooooooo -—•
oooooooooooooooooo
>ooooooooooooooooo
lOOOOOOOOOOOOOOOOO
.oooooooooooooooooo
ooooooooooooc
-
:::
* ** *
liisiisiliiiiiiiiiiii
•M 1 1 1 1 I 1 1 M l'|
Silt (Filter)
1
Sand (Buffer)
Special Precautions and Limitations
None.
3.3.6.4 Principal Data Requirements
Accessibility of cover materials (implementibility and
cost)
Soil characteristics (suitability to cover function):
156
-------
TABLE 3-26
PRIMARY FUNCTION OF COVER LAYERS
Ui
Reduce Reduce Wind Provide Enhance
Reduce Water Erosion/Dust Control Gases Surface for Cover
Layer Infiltration Erosion Emissions and Odors Vegetation Integrity
Barrier
Buffer
Filter
Gas channel
Top soil
X
X
X
X
X
X
X
X
X
-------
TABLE 3-27
RANKING OF USCS SOIL TYPES ACCORDING TO PERFORMANCE OF COVER FUNCTION
Ul
CO
USCS
Symbol
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
Ft
Key: E
Typical Soils
Well graded gravels, gravel-sand
mixtures, little or no fines
Poorly graded gravels, gravel-
sand mistures, little or no
fines
Silty gravels, gravel-sand-silt
mixtures
Clayey gravels , gavel-sand-clay
mixtures
Well-graded sands, gravelly
sands, little or no fines
Poorly graded sands, gravelly
sands, little or no fines
Silty sands, sand-silt mixtures
Clayey sands, sand-silt mixtures
Inorganic silts and very fine
sands, rock flour, silty or
clayey fine sands, gr clayey
silts with slight plasticity
Inorganic clays of low to medium
plasticity, gravelly clays,
sandy clays, silty clays, lean
clays
Organic silts and organic silty
clays of low plasticity
Inorganic silts, micaceous or
diatomaceous fine sandy or silty
soils, elastic silts
Inorganic clays of high
plasticity, fat ciays
Organic clays of medium to high
plasticity, organic silts
Peat and other highly organic
soils
= Excellent; G = Good; F = Fair;
Hater Infiltration
Trafficability Impede Assist
E F G
E P E
G F F
G G F
E F G
E P E
E-G F G
G-F F F
G-F G F
F E P
F - -
F G F
F E P
P - -
P - -
P = Poor
Gas Migration Erosion
Impede Assist Water
FEE
FEE
F G G
G F G
F G E
F G E
F G F
G F F
G F P
E F P
- - P
- - F
E F F
- - F
- - G
Control
Wind
E
E
G
G
E
E
G
F
F
F
F
F
F
-
-
Crack
Resistance
E
E
G
G
E
E
E
G
G
F
F
F
F
F
-
Support
Vegetation
F
F
F
G
F
F
E
E
G
F
G
G
F
F
G
Source: Lutton, et.al., 1979
-------
TABLE 3-28
CHEMICAL ADDITIVES FOR COVER SOIL
Category and Agent
Attribute*
Water Dust/Wind
Comments**
Inorganic chemicals
Calcium chloride
Lime
Phosphoric acid
Potassium silicate
Sodium carbonate
Sodium chloride
Sodium silicate
Sodium silicate N
Sodium silicate No. 9
Soil lok
Resinous materials
Aerospray 52
Aerospray TO
AM-9
Amoco A
Amoco B
Aniline-furfural
Aniline hydrochloride
furfural
Aroplaz 6065
Aropol 7110
Aropol 7720 M
Arothane 156
Yes Yes Yes Maintains moisture content. Easily
leached out by water.
Yes See discussion in text.
Yes Cementing agent. Mixes easily with soil.
See discussion in text.
Yes Easily leached out by water.
Effective in well-graded, compacted sand.
Forms hard crust after 1-hour cure.
Effective in sands.
Effective when sprayed on. Approximate
cost $0.60/gal.
Combination sodium silicate and calcium
chloride. Effective in fine-grained soils.
Forms hard surface.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes Alkyd resin emulsion that forms a hard
crust. Approximate cost $2.85/gal.
Yes Polyvinyl acetate resin emulsion. Effec-
tive in sand. Approximate cost $2.50/gal.
Yes Blend of water-soluble acrylamide and
diacrylamide. Provides flexible surface
after long curing.
Requires moisture and temperatures above
UO°F (lt°c) to cure. Effective mixed with
sand.
Fast curing resin. Effective mixed with
sand.
Yes Yes Provides tough surface for dry silt and
clay. 'Soil moisture reduces final strength
Toxic.
Nontoxic resin. Effective Un highly acid
or neutral soils with Pi's of 3 to 20.
Yes
Yes Unsaturated polyester resin. Significantly
increases soil strength of sand, silt, or
clay.
Yes Unsaturated polyester resin. Effective in
sand, silt, or clay.
Yes Polyurethane elastomer with rapid curing.
(Continued)
159
-------
TABLE 3-28
CHEMICAL ADDITIVES FOR COVER SOIL (Cont.)
Attribute*
Category and Agent
Water Dust/Wind
Comment SM
Resinous materials (continued)
Arothane 160
Arothane 170
Ashland CR 726
Base 792-D
Base 792-L
Celanese 13-67-5
Celanese 510+872
Celanese 16-78-16
Celanese 16-78-1
Celanese 16-77-1
Chem-Rez 200
Chrome lignin
CIBA 509+X8157/136
CIBA 6010+X8157/136
CIBA 6010+X8157/157
DCA-70
DCA-1295
Dow CX-7
Dow derakene 11U
Dresinate DS-60W-80F
Edoco X-2111-1
Onion E-200
Yes Yes Yes Polyurethane elastomer with rapid curing.
Effective in clay.
Yes Yes Yes Similar to Arothane 160.
Yes Blend of resorcinol and an accelerator.
Effective mixed with clay.
Yes Blend of polyvinyl resins and modifiers.
Yes Similar to Base 792-D.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Blend of EpiRez 510 and EpiCure 872.
Effective mixed with sand.
Blend of EpiRez 510, 5kk, and EpiCure
8701. Requires moisture to cure. Effec-
tive mixed with sand.
Blend of EpiRez 510, 856, and EpiCure 87.
Effective mixed with sand or clay.
Yes Furfural based rapid setting resin.
Effective in sand or clay.
Yes Risinous alkali waste and a hexavalent
chromium compound in gel form.
Blend of Araldite 509 and X8157/136.
Effective mixed with clay.
Blend of Araldite 6010 and X8157/136.
Effective with sand or clay of variable
moisture content.
Yes
Yes Yes Emulsion of polyvinyl acetate and chemical
modifiers. Cures in 2 to U hours. Can be
reinforced with fiberglass filaments.
Yes Yes Improved DCA-70. Fiberglass reinforcement
may be harmful if inhaled or blown into
eyes.
Yes Blend of vinyl ester resin, benzoyl peroxide,
and N. B. dimethylanitine. Fast curing.
Effective mixed with sand.
Yes Blend of vinyl ester resin, benzoyl peroxide,
and N. N. dimethylanitine. Requires moisture
to cure. Effective mixed with sand or clay.
Yes Thermoplastic resin. Effective in spray
applications. Approximate cost $0.3'»/6al.
Yes Effective in sand or clay.
Yes Yes Yes Water soluble resin that cures within 2 hours
in combination with diethylene triamine.
Effective in sand or clay.
(Continued)
160
-------
Table 3-28
CHEMICAL ADDITIVES FOR COVER SOIL (Cont.)
Attribute*
Category and Agent
Water Dust/Wind
Comments'*
Resinous materials (continued)
Epon 828 Yes
Epon 828+Vl»0 Yes
General latex-vultex Yes
General Mills TSX-i429+TSX-l*28 Yes
HK-1
HK-2 Yes
Jones-Dabney No. 6 Yes
Jones-Dabney No. 7 Yes
Lignin liquor
Ligno sulfonates Yes Yes
Lino-cure C Yes
Norlig Itl Yes Yes
Orzan Yes Yes
Paracol TC1842
Paracol Slk6l
Petroset RB Yes Yes
Petroset SB Yes Yes
R 20 Yes
Resinox 9673 Yes
Resin 321 Yes
Yes Epoxy resin with slow curing time. Pene-
trates sand or clay and forms a hard
crust.
Blend of Epon 828 and VUO. Effective in
sand or clay.
Blend of an epoxy resin and a catalyst.
Causes low strength gain.
Blend of a resin and a coreactive resin.
Causes low strength gain.
Yes 1:1 mix of Base 792-D and 792-L.
Yes 3:1 mix of Base 792-D and 792-L. Forms
tough resilient film but curing can take
more than 7 hours with loose sand in
humid conditions.
Blend of EpiRez 5159, 50ltU, and EpiCure
87!*. Effective in sand or clay.
Yes Resinous alkali waste and compounds.
Yes See Norlig Ul.
Foundry resin that forms a hard, water-
proof surface when applied with ethylene
glycol.
Yes Ligno sulfonate. Approximate cost
$0.27/gal.
Yes Mixture of ligno sulfonate and chemicals.
Forms shrinkage cracks when cured. May be
leached out by water.I
Yes Resin emulsion. Good results with mine
tailings.
Yes Blend of wax and resin. Effective with
mine tailings. Approximate cost $0.39/gal.
Yes Emulsion of resins, elastomer, and volatile
solvents. Effective in gravel and rock.
Approximate cost $2/gal.
Yes Emulsion of resins, elastomer, oils, sol-
vents, and water. Effective in particles
below gravel size. Approximate cost
$1.60/gal.
Sodium methyl silanolate. Nonbiogradable.
Approximate cost $0.05/yd2 treated.
Finely powdered resinous substance. Effec-
tive in acid soils (silty clay and clayey
silt).
(Continued)
161
-------
TABLE 3-28
CHEMICAL ADDITIVES FOR COVER SOIL (Cont.)
Attribute*
Category and Agent
Water Dust/Wind
Comment^**
Resinous materials (continued)
Soil seal
Vinsol
Vistron silmar 3-381*0
Whitesides 69-Y-l
Polymeric materials
Compound SP 301
Curasol AE
Curasol AH
Neoprene 750
Petroset KB
Petroset SB
Petroset AX
Petroset AT
Polyco 2l»60
Surfaseal
Terra-krete
Ucar 130
Vultex l-V-10
White soil stabilizer
Bituminous materials
APSE (Asphalt penetrative
soil binder)
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Emulsion of material copolymers in the
plastic resin range. Effective in fine-
grained sand.
Powdered resinous substance. Effective
in sandy silt, silty sand, clayey silt,
and clayey sand. Susceptible to nicro-
bial attack.
Modified polyester resin. Requires mois-
ture to cure. Causes low strength gains.
Emulsified epoxy resin. Effective mixed
with clay.
Latex copolymer emulsion. Effective in
spray application. Approximate cost
$1.30/gal.
Polyvinyl acetate latex dispersion. Forms
a hard crust. Cleanup is difficult.
Approximate cost $2.60/gal.
Polyvinyl acetate latex. Forms a flexible
crust.
See Resinous materials.
See Resinous materials.
Emulsion of elastomer, asphalt, solvents,
and water.
Yes Emulsion of elastomer, oils, and water.
Styrene/butadiene latex. Effective in
spray applications. Approximate cost
$0.87/gal.
Yes Viscous plastic material. May require
several applications, allowing drying time
prior to each additional application.
Approximate cost $l*.UO/gal.
Yes Chemicals in latex base. Forms hard
surface.
Yes Polyvinyl acetate.
Yes Prevulcanized rubber latex.
Latex polymer, effective mixed with soil.
Approximate cost $U.31/gal.
Yes Low penetration grade asphalt, kerosene,
and naptha. Good penetration in impervious
or tight soils. Cures in 6 to 12 hours.
Flammable.
(Continued)
162
TIT"
-------
TABLE 3-28 (Continued)
Category and Agent
Attribute*
Strength Water Dust/Wind
Comments**
Bituminous materials (continued)
Liquid shale tar (shale oil) Yes
Peneprime
Petroset AX Yes Yes
Miscellaneous materials
Admex 710
Aggrecote 600
Aquatin Yes
Bio-binder Yes
Bisphenol A
Calcium acrylate Yes Yes
Calcium sulfonate Yes
Cyanaloc 62 Yes
Dust bond 100 Yes
Dustrol Yes
ELO
Formula 125 Yes
Gelatin 15XPF Yes
Goodyear X335
Heavetex P1396 Yes
Heavetex P1397 Yes
Hysol Yes
K-aton 101
Landlock
Lemac 1*0
Orzan GL-50 Yes
Pacific N 7>*8 K Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Effective in sand or clay.
Same as APSB.
See Polymeric materials.
Concentrate of chemicals and pectin.
Forms fragile crust. Stains skin, cloth-
ing, and equipment. Approximate cost
$2.30/gal.
For spray applications.
cost $2.57/gal.
Approximate
Organic salt that forms strong bonds
in wet, fine-grained soils.
Approximate cost $0.36/gal.
Medium grade road oil. Flammable.
Organic cementing agent and a sodium
methyl siliconate base. Effective in
gravel to clay. Caustic in concentrated
form. Approximate cost $10/gal.
Good penetration in sand.
brittle surface.
Forms hard,
Cementing material that can be sprayed
or mixed with soil. Approximate cost
$0.30/gal.
(Continued)
163
-------
TABLE 3-28
CHEMICAL ADDITIVES FOR COVER SOIL (Cont.)
Attribute*
Category and Agent Strength Water Dust/Wind Comments**
Miscellaneous materials (continued)
Stabinol Yes 3:1 mix of Portland cement and Resin 321
or a complex salt. Deteriorates after
long storage.
Sulfite liquor Yes Effective sprayed on sand and gravel.
Easily leached out by water.
Terra-krete No. 2 Yes Inorganic and organic materials vith a
synthetic binder. Approximate cost
$2.50/gal.
Tung oil Yes
Waste oil Yes Yes Yes
* Attributes are marked yes where addition to soil is claimed (not necessarily substantiated) to stabilize
generally, to repell water or resist water erosion, or to resist dusting or wind erosion. Dispersants
are another group of additives used primarily to aid in the compacting process; they are not included in
this table but are discussed in the text.
** The pollution potential of additives should be given special consideration prior to usage.
Source: Lutton et al., 1979
• type (USCS or USDA classification)
• grain size distribution
• compaction
• strength properties
• erosion potential
• permeability
• capillary head
• clay mineralogy
Waste characteristics (cover function requirements):
• chemical
• physical
• disposal practices
164
-------
:.IABLE 3-29
PRODUCTS RECOMMENDED FOR PRIORITY COVER
Material and Description
Advantages
Disadvantages
Bitumen cements or concretes
(AC-40 and AC-20 viscosity
grades.)
Portland cements or concretes
(3000 psi and 5000 psi)
Liquid and emulsified asphalts
(RC and EC 30, 70, 250, 800,
and 3000 liquid asphalts.
RS's and CRS's 1 and 2, MS's
emulsion.)
Tars
(RT 1, 2, 3, 4, 7, 8, and 9.
RTCB 5 and 6).
Bituminous fabrics
Commercial polumeric membranes
(Butyl rubber)
a. Provide tight, impervious barriers
covering municipal/hazardous waste.
b. Good availability.
c. May be used as thick waterproofing
layers in flat areas or on slopes.
a. Good availability.
b. Provides good highly impermeable
containers or covers for hazardous
waste disposal. Very low water
permeability.
a. Can be sprayed on soil covers to
decrease water and gas permeability
b. Can be mixed with soil to form
waterproof layer.
c. Penetrate open surfaces, plug voids,
then cure.
d. Penetrate tight surfaces, plug
voids, then cure.
e. Provide hard, tight, stable
membrane (RC and MC 800 and 3000)
a. Can be sprayed on soil surfaces or
mixed with particles. Tars mix well
with wet aggregate.
b. Penetrate tightly bonded soil
surfaces and plug voids (RT 1 and 2).
c. Penetrate loosely bonded fine
aggregate surfaces and plug voids
(RT 2, 3, and 4).
d. Penetrate loosely bonded coarse
aggregate 'surfaces and plug voids
(RT 3 and 4).
e. Low spray on temperatures 60° to
150°F (15° to 65°C) for RT 1, 2, 3,
and 4 and RTCB 5 and 6.
f. Provide hard, tight, stable surface
membrane (RT 7, 8, and 9). May be
used in flat areas or on slopes.
g. Provide good penetration, then cure
to form hard surface (RTCB 5 and 6).
a. Require minimal special equipment
and skill.
b. Resist tearing.
a. Available in various size sheets.
b. Can be reinforced with fibers for
added strength.
c. Can be joined at seams to cover
d. Good availability.
e. Good heat resistance.
a. Expensive
b. Special heating and storage equip-
ment required for handling.
c. Vulnerable to breaking.
a. May crack during curing, allowing
potential paths for escaping gases
or infiltrating water.
b. Leakage from hazardous wastes in
liquid form may weaken concrete
with time
a. Must leave sprayed surface exposed
until it either cures (RC's, MC's)
or sets (SS's).
b. Must be covered for protection.
c. Require additional equipment to
handle and apply the asphalts.
Spraying temperatures range from
75° to 270°F (25° to 130°C).
d. Use of RC and MC 800 and 3000 in
thick membrane construction may
require numerous applications.
a. Tar may be removed by traffic if
not covered with a protective
soil layer.
b. Tars are more susceptible to
weathering effects than asphalts.
Must be protected from weathering.
c. Require special equipment for
handling and application.
d. RT 7, 8, and 9 require application
temperatures of 150° to 225°F
(65° to 105°C).
a. Expensive
b. Laps should be sealed.
a. Poor resistance to weathering
and abrasion.
b. May be damaged by gnawing/burrowing
animals if not protected with soil.
c. May be damaged by heavy equipment
operating directly on surface and
may be punctured by large stones or
sharp edges in direct contact.
165
-------
TABLE 3-29
PRODUCTS RECOMMENDED FOR PRIORITY COVER (Cont.)
Material and Description
Advantages
Disadvantages
Commercial polymeric met
(continued)
(Neoprene rubber
(chloroprene ruober))
(Hypalon (chlorinated
chlorosulfinated
polyethylene))
(Polyolefin (polyethylene
and chlorinated
polyethylene))
(Elasticized polyoiefir.
OUt»)
f. Very low water permeability.
g. Low vapor transmissivity.
Good resistance to oils, grease,
gasoline, acids, and alkalies.
Good resistance to abrasion,
weathering, and flexing.
Can be joined at seams to cover
large areas.
Can be reinforced with fibers for
added strength.
Very low water permeability.
Outstanding resistance to abrasion
and weathering.
Available in various size sheets.
Can be fiber reinforced for added
strength.
Can be joined at seams to cover
large areas. This can be done
onsite or at factory.
Very low water permeability.
a. Available in various sizes.
b. Can be joined at seams to cover
large areas.
c. Can be fiber reinforced.
d. Chlorinated polyethylene has
excellent outdoor durability.
e. Very low water permeability.
a. Can be joined an seams to cover
large areas. Field bonding of
individual sheets is done using
a heat seaming techniques.
b. Excellent resistance to soil micro-
organisms, extremes of weather, and
ozoae attack.
c. Very lov water permeability.
More expensive than other natural
and synthetic rubbers.
Use is limited to special appli-
cations because of a_ above.
May be damaged by gnawing/burrowing
animals if not protected with a
soil layer.
May be damaged by heavy equipment
operating directly on surface and
may be punctured by large stones or
sharp edges in direct contact.
Kay be damaged by gnawing, burrowin?
animals if not protected with a
soil layer.
Does not perform satisfactorily
when exposed to amyl acetate,
benzene, carbon tetrachloride,
creosote oil, cyclohexane, dioctyl
phthalate, ethyl acetate, lacquer
lethylene chloride, napthalene,
nitrobenzene, oleum, toluene,
tributyl phosphate, trichloroethy-
lene, turpentine, and xylene.
For good seam quality, the weather
must be at least 50°F (10°C) and
sunny. If not, heat has to be
applied to seams to develop full
early strength.
May be damaged by heavy equipment
operating directly on membrane.
May be punctured by large stones on
sharp edges in direct contact.
May be damaged by gnawing/burrowir.g
animals if not protected with a soil
layer.
May be damaged by heavy equipment
operating directly on membrane.
May be punctured by large stones
or sharp edges in direct contact.
Polyethylene has poor durability
when exposed.
May be damaged by gnawing/burroving
animals if not protected with' a
soil layer.
May be damaged by heavy equipment
operating directly on membrane.
May be punctured by lar?e stones
or sharp edges in direct contact
wich membrane.
166
-------
TABLE 3-29
PRODUCTS RECOMMENDED FOR PRIORITY COVER (Cont.)
Material and Description
Advantages
Disadvantages
Commercial polymeric membranes
(continued)
(PVC (polyvinyl chloride)
(EPDM (ethylene-propylene-
unsacurated diene
t^rpolymer))
Sulfur (thermoplastic
coating) (Molten sulfur)
Bentcnite
a. Fair outdoor durability.
b. Available in sheets of various
sizes. Factory seaoiing available
c. Seams can be bonded in the field
with vinyl to vinyl adhesive.
d. Generally used without reinforcement,
however, can be fiber reinforced
for special applications.
e. Very low water permeability.
f. Less permeable to gas than
polyethylene.
a. Good outdoor durability. Ozone and
oxidation resistant.
b. Sheets may be bonded to cover large
areas.
c. Very low water permeability.
a. Can be formulated for a wide range
of viscosities.
b. Can be sprayed on various materials
to act as a bonding agent.
c. Reduces permeability.
d. Resistant to weather extremes
(subfreezing to very hot).
e. Resistant to acids and salts.
f. Can be mixed with fine aggregate to
form a type of concrete.
a. No special equipment needed.
b. Can be mixed with soil.
a. May be damaged by gnawing/burrowing
animals if not protected with a
soil laver.
b. For extended life, tnis membrane
must be covered with soil or other
material.
c. May be damaged by heavy equipment
d. Not as durable as bypalon or
chlorinated polyethylene.
e. Becomes stiff in cold weather.
May be damaged by gnawing/burrowing
animals if not protected with a
soil layer.
May be damaged by heavy equipment
operating directly on surface and
may be punctured by large stones or
sharp edges in direct contact.
Requires high temperatures for
workability, 250° - 300°F
(20° - 150°C).
Reauires special equipment for
handling and application.
May not tolerate much shear
deformation.
If applied to hazardous waste
containers prior to land disposal,
heat absorption by volatile wastes
may cause gas expansion and possible
explosion hazards.
Difficult to handle and
spread after wetting.
Susceptible to shrink-swell.
Source: Lutton et al, 1979
167
-------
Climatology (cover function requirements):
• precipitation
• evapotranspiration
• storm characteristics
• wind characteristics
• air quality
Infiltration (cover function requirements)
Runoff (cover function requirements)
3.3.6.5 Elements of Cost Review
Components
Construction and Capital--
• material for various layers
• equipment
• transportation
0 & M--
• Inspection and maintenance
Major Factors
• size of site
• layers required
• material used for each layer
• transportation
168
-------
Data
Unit cost for surface seals are given in Table 3-30.
Unit costs for a bituminous concrete seal 55,000 m2, including
excavation and grading, in 1982 dollars, is $275,000 - $379,000
(SCS, 1980).
3.3.7 Vegetation
3.3.7.1 Description
Vegetation can perform four basic functions:
• It can stabilize soil and earthen structures against wind
and water erosion by intercepting rainfall, slowing runoff,
and holding soil together with a-tight root system.
• It can reduce the quantities of water available for runoff
through interception, infiltration, uptake and transpira-
tion.
• It can treat contaminated soil and leachate through the
uptake and removal of waste constituents, nutrients, and
water from the soil.
• It can improve the aesthetic appearance of the site.
Plants used for revegetation include various types of grasses,
legumes, shrubs and trees. A revegetation program involves careful
plant selection, land preparation (such as increasing soil depth,
grading, fertilizing and tilling), seeding, and maintenance.
3.3.7.2 Status
Conventional, demonstrated.
3.3.7.3 Feasibility and Effectiveness
169
-------
TABLE 3-30
UNIT COSTS FOR SURFACE SEALS
Cover Material and/or Method of Installation
1982 Unit Costs
Topsoil (sandy loam), hauling, spreading and grading
(within 20 miles)
Clay hauling, spreading and compaction
Sand hauling
spreading and compaction
Cement concrete (4 to 6" layer), mixed, spread
compacted on-site
Bitumeonus concrete (4 to 6" layer, including
base layer)
Lime or cement, mixed into 5" cover soil
Bentonite, material only; 2" layer, spread and
compacted
Sprayed asphalt membrane (1/4 layer and soil cover),
installed
PVC membrane (20 mil), installed
Chlorinated PE membrane (20-30 mil), installed
Elasticized polyolefin membrane, installed
•n
Hypalon membrane (30 mil), installed
Neoprene membrane, installed
Ethylene propylene rubber membrane, installed
Butyl rubber membrane, installed
Teflon-coated fiberglass (TFE) membrane
(10 mil), installed
Fly ash and/or sludge, spreading, grading
and rolling
$15.73/yd~
$16/29/ydJ
$18.15/yd3
$9,680-12,200-acre
$7.26-12.10/yd2
$3.81-6.35/yd"
$1.91-2.67/7^
$1.78/yd2
$L91-3.18/yd"
$1.65-2.54/yd
$3.05-4.06/yd2
$3.27-4.36/yd^
$7.87/yd2
$6.05/yd2
$3.43-4.44/yd"
f
$3.43-4.83/yd"
$24.20/yd2
$1.27-2.16/7
-------
Characteristics
important characteristics of selected grasses, legumes,
shrubs, and trees are given in Tables 3-31 through 3-34. A concise
list of the major characteristics of over 800 species of plants can
be found in Dukes, 1978.
Selection
Selection of vegetation will depend on site-specific require-
ments and plant characteristics. In general, grasses provide quick
and lasting dense growth. They effectively anchor the soil, have
high evapotranspiration characteristics, and may be suitable in wet
areas such as waterways. They do, however, require periodic mowing
and maintenance (TRD 11).
Legumes, on the other hand, are a low maintenance cover provid-
ing long-term protection. They are most suitable for stabilization
and erosion control and are useful even on steep slopes. They also
have the added benefit of increasing soil fertility through nitrogen
fixation (TRD 11).
Shrubs are useful in providing a dense surface cover and are
tolerant to acidic soils (TRD 11).
Trees are most suited to preparing a site for post-closure use.
They help provide a long-term protective cover and build up a
stable, fertile layer of decaying leaves and branches (EPA, 1982).
Indigeneous species (those growing naturally in the site
region) should be used wherever possible (TRD 11) .
Maintenance
Temporary stabilization against erosion may be required while
vegettation is being established. Techniques include:
• straw-bale check dams (for waterways)
171
-------
TABLE 3-31
CHARACTERISTICS OF COMMONLY USED GRASSES
JJ
Common
name
Bthiagrass
Barley
Bermuda grats
Bluegrass,
Canada
Bluegrati,
Kentucky
Bluettem,
big
Bluestem,
little
Bromegrass,
field
Bromegrass,
smooth
Buffalograss
Cariarygrass,
reed
Deertorrue
Fescue,
• r'i i
creeping r«J
Fescue, tall
Grama, blue
Grama,
sideoats
Indian grass
Lovegrass,
sand
Lovegrass
weeping
Season
Coo. Warm °'¥ ("°\
droughty)
X X
X
X X
X X
X
X
X
X
X X
X
X X
X X
X X
X
X X
X
X
X
X X
Site suitability
„. .. Moderately Somewhat „ ,
Well Poorly
. . . well poory .
drained ... . . . drained
drained drained
X X
X X
XXX
X X
XXX
XXX
X X
XXX
XXX
X X
X XXX
X XXX
XXX
XXX
XXX
X X
X X
X
XXX
Growth pH
habit*1 range0
P 4.5-7.5
A 5.5-7.8
P 4.5-7.5
P 4.5-7.5
P 5.5-7.0
P 5.0-7.5
P 6.0-8.0
A 6.0-7.0
P 5.5-8.0
P G.5-8.0
P 5.0-7.5
P 3.8-5.0
P 5.0-7.5
P 5.08.0
P 6.0-8.5
P 6.0-7 5
P 5.57.5
P 6.07.5
P 4.5-8.0
Use suitability
_ .... Waterways
Erodible . ' . . d
and Agriculture
areas
channels
XXX
X X
XXX
X X
XXX
X X
X X
X X
XXX
X X
XXX
X X
XXX
XXX
X
X X
X X
X X
X
Remarks
Tall, extensive root system. Maintained at low cost once
established. Able to withstand a large range of soil con-
ditions. Scarify seed.
Cool season annual. Provides winter cover.
Does best at a pH of 5.5 and above. Grows best on well
drained soils, but not on waterlogged or tight soils. Propa-
gated vegetatively by planting runners or crowns.
Does well on acid, droughty, or soils too low in nutrients to
support good stands of Kentucky bluegrass.
Shallow rooted; best adapted to well-drained soils of lime-
stone origin.
Strong, deep rooted, and short underground stems. Effective
in controlling erosion.
Dense root system; grows in a clump to 3 feet tall. More
drought tolerant than big bluestem. Good surface pro-
tection.
Good winter cover plant. Extensive fibrous root system.
Rapid growth and easy to establish.
Tall, sod forming, drought and heat tolerant. Cover seed
lightly.
Drought tolerant. Withstands alkaline soils but not sandy
ones. Will regenerate if overgrazed.
Excellent for wet areas, ditches, waterways, gullies. Can
emerge through 6 to 8 inches of sediment.
Very acid tolerant; drought resistant. Adapted to low fer-
tility soils. Volunteers in many areas. Seed not available.
Grows in cold weather. Remains green during summer. Good
seeder. Wide adaptation. Slow to establish.
Does well on acid and wet soils of sandstone and shale origin.
Drought resistant. Ideal for lining channels. Good fall
and winter pasture plant.
More drought resistant than sideoats grama. Sod forming.
Extensive root system. Poor seed availability.
Bunch forming; rarely forms a sod. May be replaced by blue
grama in dry areas. Feed value about the same as big
bluestem. Helps control wind erosion.
Provides quick ground cover. Rhiiomatous, tall. Seed avail-
able.
A bunchgrass of medium height. Adaptable to sandy sites.
Good for grazing. Fair seed availability.
lunchgrass, rapid early growth. Grows well on infertile soils.
Good root system. Low payability. Short-lived in North-
east.
-------
TABLE 3-31
CHARACTERISTICS OF COMMONLY USED GRASSES (Cont,
Common
name
Millet, foxtail
Oats
Oetgrats, tall
Orchard grass
fledtop
Rye, winter
Ryejress,
annual
Ryegratt,
„--—.. — ;-|
perennial
Sandraed,
prairie
iudangran
Switchgrass
Timothy
Wheat, winter
Wheatgrast,
t»ll
latl
rheatQrass,
western
Season
Cod Warm "? (B01,
droughty)
X X
X X
X X
X X
X X
X X
X
X
X X
X X
X
X
X X
X X
,
X X
Site suitability
... Moderately Somewhat _
Well Poorly
. . . well poor y
drained ... . . * drained
drained drained
X X
X
<
X
XXX
X XXX
X X
XXX
XXX
X
'x x x
XXX
X XXX
XXX
X XXX
X XXX
Growth pH
habit b range0
A 4.5-7.0
A 5.5-7.0
P 5.0-7.5
P 5.0-7.5
P 4.07.5
A 5.57.5
A 5.5-7.5
P 5.5-7.5
P 6.0-8.0
A 5.5-7.5
P 5.0-7.5
P 4.5-8.0
A 5.0-7.0
P 6.0-8.0
P 4.5-7.0
Use suitability
r .1-1.1 Waterways
Erodible ' „ d
and Agriculture0
channels
X X
X X
X X
X X
XXX
X X
X X
X X
X
X X
XXX
X X
X X
XXX
XXX
Grasses ihould be planted in combination with legumes. Seeding rates, time, and varieties should be based on local recommendations
Remarks
Requires warm weather during the growing season. Cannot
tolerate drought. Good seedbe(j preparation important.
Bunch forming. Winter cover. Requires nitrogen for good
growth.
Short-lived perennial bunchgrass, matures early in the spring.
Less heat tolerant than orchardgran except in Northeast.
Good on sandy and shallow shale sites.
Tall-growing bunchgrass. Matures early. Good fertilizer
response. More summer growth than timothy or brome-
grass.
Tolerant of a wide range of soil fertility, pH, and moisture
conditions. Can withstand drought; good for wet condi-
tions. Spreads by rhizomes.
Winter hardy. Good root system. Survives on coarse, sandy
spoil. Temporary cover.
Excellent for temporary cover. Can be established under dry
and unfavorable conditions. Quick germination; rapid
seedling growth.
Short-lived perennial bunchgrass. More resistant than weep-
ing love or tall oatgrass.
Tall, drought tolerant. Can be used on sandy sites. Rhizome-
tout. Seed availability poor.
Summer annual for temporary cover. Drought tolerant.
Good feed value. Cannot withstand cool, wet soils.
Withstands eroded, acid and low fertility soils. Kanlow and
Blackwell varieties most often used. Rhizomatous. Seed
available. Drainageways, terrace outlets.
Stands are maintained perennially by vegetative reproduction.
Shallow, fibrous root system. Usually sown in a mixture
with alfalfa and clover.
Requires nutrients. Poor growth in sandy and poorly drained
soils. Use for temporary cover.
Good for wet, alkaline areas. Tolerant of saline conditions.
Sod forming. Easy to establish.
Sod forming, spreads rapidly, slow germination. Valuable for
°f = perennial; A « annual.
'Many species survive and grow at lower pH; however, optimum growth occurs within these ranges.
Hay. pasture, green manure, winter cover, and nurse crops are primary agricultural uses.
Source: EPA, 1976, Vol. 1
GJ
-------
TABLE 3-32
CHARACTERISTICS OF CONMONLY USED LEGUMES
Common
name
Alfalfa
Clover, Alsike
Clover, red
Clover, white
Flatpea
Lespedeza,
common
Lespedeza,
Korean
Lespedeza.
sericea
Milkvetch,
cicer
Sweetclover,
white
Sweetclover,
yellow
Trefoil,
birdsfoot
Vetch, crown
Vetch, hairy
Season
Cool Warm Dry
X X
X
X
X
X X
X
X X
X X
X
X X
X X
X X
X X
X X
Site suitability
Moderately Somewhat „ ,
Well „ . Poorly
. . well poorly .
drained ... . . . drained
drained drained
X X
X X XX
X X
XXX
XXX
X X
XXX
XXX
XXX
X X
X X
XXX
X X
X X
Growth pH
habit'' range0
P 6.5-7.5
P 5.0-7.5
P 6.0-7.0
P 6.0-7.0
P 5.0-6.0
A 5.0-6.0
A 5.0-7.0
P 5.0-7.0
P 5.0-6.0
B 6.0-8.0
B 6.0-8.0
P 5.0-7.5
P 5.5-7.5
A 5.0-7.5
Use suitability
c j-ui Waterways
Erodible ' ... d
and Agriculture
areas . .
channels
X X
X X
X X
X X
X
X
X
X X
X X
X X
X X
X X
X X
X X
Remarks
Requires high fertility and good drainage.
Good for seeps and other wet areas. Dies after 2 years.
Should be seeded in early spring.
Stand thickness decreases after several years.
Seed is toxic to grazing animals. Good cover.
Low-growing, wildlifelike seed. Kobe variety most often used.
Acid tolerant.
Less tolerant of acid soils than common lespedeza.
Woody, drought tolerant, seed should be scarified. Bunchlike
growth.
Drought tolerant. Low growing. No major diseases. Hard seed
coat.
Requires high-pH spoil. Tall growing. Produces higher yields.
Less reliable seed production.
Requires high-pH spoil. Tall growing. Can be established better
than white Sweetclover in dry conditions.
Survives at low pH. Inoculate with special bacteria. Plant with a
grass.
Excellent for erosion control. Drought tolerant. Winter hardy.
Adapted to light sandy soils as well as heavier ones. Used most
often as a winter cover crop.
--J
-p-
"Legumes should be inoculated. Use four times normal rate when hydroseeding.
bA = annual; B = biennial; P = perennial.
cMany species survive and grow at lower pH; however, optimum growth occurs within these ranges.
dHay, pasture, green manure.
Source: EPA, 1976, Vol. 1
-------
TABLE 3-33
CHARACTERISTICS OF COMMONLY USED TREES
Common Name
Remarks
Trees, conifers:
Virginia pine
Pitch pine
Loblolly pine
Scotch pine
Shortleaf pine
White pine
Austrian pine
Japanese larch
Red pine
Rocky Mountain juniper
Eastern red cedar
Mugho pine
Tolerant of acid spoil. Use for esthetics and where other species will not
survive. Slow development. Good for wildlife.
Deep rooted and very acid tolerant. Can survive fire injury. Deer like small
seedlings. Plant in bands or blocks.
Very promising species, rapid early growth. Marketable timber products.
Can survive pH 4.0 to 7.5. Susceptible to ice and snow damage.
Good for Christmas trees if managed properly. Can be planted on all slopes
and tolerates pH of 4.0 to 7.5.
Some insect problems. Will sprout freely if cut or fire killed when young.
Good marketable timber.
May be used for Christmas trees. Has poor initial growth but improves with
time. Plant in bands or blocks.
Can be planted on all slopes. Plant in bands or blocks. When planted near
black locust, deer cause browse damage.
Should be planted on unleveled and noncompacted spoil. Provides good
litter.
Sawfly damage in some areas. Plant on all slopes. Light ground
cover.
Has shown good survival on Kansas spoil materials. Compact growth varie-
ties have from silver to purple colors.
Tall, narrow growth. Best on dry, sandy soils. Good with black locust. pH
5.0 to 8.0.
Survives on acid spoil. Develops slowly. Low growing. Good cover for
wildlife.
Trees, hardwoods:
Black locust
Bur oak
Cottonwood
European black alder
Green ash
Hybrid poplar
Red oak
European white birch
Sycamore
Can be direct seeded. Wide range of adaptation. Rapid growth; good leaf
litter. Use mixed plantings. Dominant stem clones preferred.
Better survival with seedling transplants than acorns. Light to heavy ground
cover.
A desirable species for large-scale planting. Good cover and rapid growth.
Pure stands should be planted.
Rapid growing. Wide adaptation. Nitrogen fixing, nonlegume. Can survive
pH 3.5 to 7.5. Adapted to all slopes.
Very promising species. Use on all slopes and graded banks with compact
loams and clays. Plant in hardwood mixture.
Rapid growth. Good survival at low pH. Marketable timber after 20 years.
Cannot withstand grass competition. Good for screening.
Makes slow initial growth. Good survival, plant on upper and lower slopes
only. Can grow from pH 4.0 to 7.5.
Makes rapid growth on mine spoil. Poor leaf litter and surface cover-
age.
One of the most desirable species for planting. Poor ground cover. Volun-
teer trees grow faster than planted ones.
Source: EPA, 1976, Vol. 1
175
-------
TABLE 3-34
CHARACTERISTICS OF COMMONLY USED SHRUBS
Common Name
Remarks
Shrubs:
Amur honeysuckle
Bristly locust
Autumn-olive
Bicolor lespedeza
Indigo bush
Japanese f leeceflower
Silky dogwood
Tatarian honeysuckle
Good for wildlife. Shows more vigor and adaptability as plants mature.
Extreme vigor. Thicket former. Good erosion control. Rizomatous, 5-7
ft tall. Excellent on flat areas and outslopes.
Nitrogen-fixing nonlegume. Good for wildlife. Excellent fruit crops. Wide
adaptation. Up to 15 ft tall.
Can be established from planting and direct seeding. Ineffective as a ground
cover for erosion control.
Has high survival on acid spoil. Leguminous. Not palatable to livestock.
Thicket former. Slow spreader. 8-12 ft tall.
Grows well on many sites, especially moist areas. Excellent leaf litter and
canopy protection. pH range of 3.5 to 7.0.
Grows best on neutral spoil pH. Can withstand pH range of 4.5 to 7.0.
Some value as wildlife food and cover plants. Poor surface protection.
Upright shrub, forms clumps. Does well on well-drained soils. Up to 12 ft
tall. Takes 2 years for good cover.
Source: EPA, 1976, Vol. 1
mulching application of straw, hay, wood chips, sawdust,
dryback, bagasse (unprocessed sugar cane fibers), excel-
sior (fine wood shavings and manure) (EPA, 1982)
chemical stabilization (including plastic films, latex
emulsions, oil-in-water and resin-in-water emulsions).
Maintenance of the vegetated area may be necessary depending on
the plant species selected. Maintenance includes mowing, removal of
invader species, e.g. seedlings of deep-rooted trees, liming, fer-
tilizing, replanting, and regrading.
Monitoring of a revegetated site is important to insure that the
species of plants selected are adequately adapting to the site.
Factors to be monitored include (Herman et al. , 1976; Oilman et al. ,
1981):
soil moisture
soil aeration/oxygen content
176
-------
• soil chemistry
• groundwater flow and chemistry
• plant condition
Special Precautions and Limitations
Temporary stabilization against erosion may be required while
vegetation is being established. Techniques include:
• straw-bale check dams (for waterways)
• mulching application of straw, hay, wood chips, sawdust,
dryback, bagasse (unprocessed sugar cane fibers), excel-
sior (fine wood shavings and manure) (EPA, 1982)
• chemical stabilization (including plastic films, latex
emulsions, oil-in-water and resin-in-water emulsions).
3.3.7.4 Principal Data Requirements
Geography (suitability and selection)
• topography
• accessibility of vegetation
• vegetation characteristics
Soil characteristics (suitability and selection)
• type
• grain size distribution
• moisture content
• depth
• nutrient levels
• pH
• organic content
177
-------
• waste concentrations
Climatology (suitability and selection)
• precipitation
• storm characteristics
• temperature
Infiltration (required function)
Surface water characteristics (suitability, selection, and
required function)
• runoff
• flood characteristics
• chemistry
• drainage characteristics
Waste description(vegetation compatibility)
• chemical characteristics
• physical characteristics
• disposal practices
3.3.7.5 Elements of Cost Review
Components
Construction and Capital--
• seedbed preparation
• seed spreading
• vegetation used
• stabilizers
178
-------
O & M--
• grass mowing
• refertilization
Major Factors
• vegetation availability
• vegetation requirements
Data
Unit costs for revegetation are given in Table 3-35.
Total costs for revegetating a 54,000 m2 (520,500 ft2) site
using native grass, .6 meters (2 ft) of additional topsoil and
mulching, in 1982 dollars, is $88,700 - 109,400 (SCS, 1980).
3.3.8 Seepage Basins and Ditches
3.3.8.1 Description
Seepage basins and ditches are used to discharge water col-
lected from surface water diversions, groundwater pumping, or leach-
ate treatment to groundwater. Both types discharge collected water
to the groundwater by allowing it to seep through the ground. They
usually have gravel-lined bases with sidewalls constructed of per-
vious material. There is considerable flexibility in designing
seepage basins and ditches, but typically they will include a sedi-
ment trap with a bypass for excess flow, an emergency overflow, and
the structure itself. Seepage basins are usually uncovered while
seepage ditches most often are backfilled with topsoil. Water is
introduced through a distribution line containing the sediment trap
(EPA, 1982). A typical seepage basin is shown in Figure 3-20, and a
typical seepage ditch is shown in Figure 3-21.
179
-------
TABLE 3-35
UNIT COSTS FOR REVEGETATION
Description
1982 Unit Costc
• Hydraulic spreading (hydroseeding),
lime, fertilizer, and seed
• Mulching, hay
• Loam Topsoil, remove and stockpile
on-site; using 200 h.p. dozer,
6' deep, 200' haul
500' haul
• Hauling loam on-site
• Spreading loam, 4-6" deep
• Plant bed preparation (unspecified),
18" deep, by machine
• Hydraulic seeding and fertilization
of large areas, with wood fiber mulch
• Mulch, hand spread 2" deep, wood
chips
• Liming slope areas
• Fertilizing, level
slope
• Seeding, level
slope
• Jute mesh, stapled (erosion control)
• Sodding, in East, 1" deep, level
slope
• Maintenance:
Grass mowing, slope
level areas
Refertilization
Weeding/pruning shrubs
$600/acre
$180/acre
$ .97/ydJ
$3.71/yd
$2.36/yd3
$.51-.89/y
-------
TABLE 3-35
UNIT COSTS FOR REVEGETATION (Cont.)
o
Description - 1982 Unit Cost
On-site planting
• Trees, evergreens 30-36" $56 ea.
36-42" $71 ea.
42-48" $101 ea.
4-5' $127 ea.
5-6' $165 ea.
Black Pines 7-8' $165 ea.
Yews 2-2.5' $42 ea.
Junipers 4-5' $56 ea.
• Shade trees (balled and burlapped)
6-8' $47 ea.
8-10' $66 ea.
1.5-2.5" diam. $178-279 ea.
2.5-4.0" diam. $445-635 ea.
Birch 8-10' $99 ea.
Oak 8-10' $107 ea.
• Shrubs (balled and burlapped)
2-3' $23 ea.
3-4' $52 ea.
4-5' $64 ea.
Honeysuckle shrub 4-5' $37 ea.
aAll costs include materials and installation (labor and equipment), unless
otherwise indicated. Note different units (acre; yd ; yd-*; each) .
Source: EPA, 1982
181
-------
FIGURE 3-20
SEEPAGE BASIN: SHALLOW DEPTH TO GROUNDWATER
(Source: EPA, 1982)
Dense turf
Seepage
basin \SSEazcasy ^ Gravel filled
trench
3.3.8.2 Status
Conventional, demonstrated.
3.3.8.3 Feasibility and Effectiveness
Lifetime
Seepage basins and ditches have a finite life and will ultimate-
ly become clogged with solids and biological growth. The loading
rate which gives the largest, useful lifetime is called the
long-term acceptance rate. The long-term acceptance rate is prima-
rily a function of three factors (Healey and Laak, 1974):
1. The initial permeability of the surrounding soil as meas-
ured by the acceptance rate of clear water, m/min, under a
hydraulic gradient of one.
2. The hydraulic gradient over the upper 5 cm (2 in. ) of soil.
3. The loading pattern to be used (continuous or intermittent
flooding).
182
-------
FIGURE 3-21
SEEPAGE DITCH WITH INCREASED SEEPAGE EFFICIENCY
(Source: EPA, 1982)
2" hay
or straw
Tile,
perforated
bitumen
fiber or
p.v.c. pipe
18" max.
1 10' min.
A plot of the long-term acceptance rate, adjusted to a hydraulic
head of 0.3 meters (1 ft), versus soil permeability is given in Fig-
ure 3-22.
Design
Design of seepage basins and ditches is based on consideration
of (Healey and Laak, 1974):
the amount and quality of water to be discharged
the permeability of the surrounding soil
the highest elevation of the water table
the depth to impermeable stratum
183
-------
FIGURE 3-22
LONG-TERM ACCEPTANCE RATE OF EFFLUENT BY SOIL
(1 gpd/sq ft = 0.41 m/day; 1 fpm = 0.305 m/min)
(Source: Healy and Laak, 1974)
Used by permission, see Copyright Notice
«J
* *,
It
H
u
u
Assumed Criteria for Design
of Seepage Field
I
I
I
.002 .0004 .001 .002 .004 .01
Soil Permeability fpm
.02
.04
The specific relationship between these parameters depends on the
combination of basins and ditches used in the seepage field.
Seepage Basins
Basin sidewalls should be made of pervious material. Gabions
can be used for vertical sidewalls and dense turf for sideslopes.
These also control erosion and slumping (EPA, 1982).
Infiltration can be improved in a basin by constructing
gravel-filled trenches along the basin floor (EPA, 1982) .
Seepage Ditches
Ditches are usually used in a parallel system.
siderations for seepage ditches include (EPA, 1982)
Important con-
184
-------
• minimum depth -- 1.2 meters (3.9 ft)
• minimum spacing -- 3.0 meters (9.8 ft)
• maximum width -- 0.5 meters (1.6 ft)
The efficiency of seepage ditches can be improved by intercon-
necting adjacent ditches with a continuous gravel bed, as shown in
Figure 3-21 (EPA, 1982).
Special Precautions and Limitations
None.
3.3.8.4 Principal Data Requirements
Depth to impermeable stratum (long-term acceptance rate)
Soil characteristics (lifetime)
• erosion potential (stabilization, sedimentation)
(see discussion on erosion control in Section 2) .
• permeability (long-term acceptance rate)
• hydraulic gradient in upper 5 cm of soil (long-term
acceptance rate)
Storm characteristics (capacity)
Groundwater characteristics (long-term acceptance rate)
• depth to water table
• infiltration
Surface water characteristics (capacity, sedimentation)
• runoff
• drainage area
• sedimentation
Loading pattern (long-term acceptance rate, capacity)
185
-------
3.3.8.5 Elements of Cost Review
Components
Construction and Capital--
• excavation
• gravel lining
• sediment trap
0 & M--
• cleaning of sediment trap
• maintenance
Major Factors
• number and size of basins and ditches
• gravel
Data
Unit costs for seepage basins and ditches are similar to those of
subsurface drains, given in Table 3-10.
3.4 SOIL AND WASTE TECHNOLOGIES
3.4.1 Excavation
3.4.1.1 Description
Excavation is accomplished by digging up waste or contaminated
soil with either a dragline unit or a backhoe. As its name
indicates, dragline equipment operates by dragging a bucket into the
186
-------
surface of the ground. The backhoe is a hydraulically-powered dig-
ging unit that can be mounted on tracked or wheeled vehicles.
3.4.1.2 Status
Conventional, demonstrated.
3.4.1.3 Feasibility and Effectiveness
Applicability
Dragline Units-- Effective for the removal of unconsol-
idated materials.
Backhoes-- Effective for the removal of compacted as well
as loosely-packed materials. Backhoes offer more accurate digging
bucket placement than the dragline. In addition, a specialized type
of backhoe unit, called a GradallR, can be used to backfill and grade
an excavation site or a drained surface impoundment. Backhoes are
also capable of removing barrels when equipped with a sling or grap-
pler for removing drummed waste.
Performance Characteristics
Digging depth and digging reach for a dragline unit and backhoe
are dependent on the boom length. Values in Table 3-36 are based on
a digging angle of 45 degrees. Other operating parameters include:
• optimum digging depth: 4.5 meters (15 ft)
• maximum digging depth:
1. Dragline: 18 meters (60 ft)(EPA, 1982)
2. Backhoe: 21 meters (70ft)(ASCE, 1982)
• theoretical production rates (see Table 3-37)
187
-------
TABLE 3-36
EXCAVATION EQUIPMENT CHARACTERISTICS
Excavation Equipment
Hoe or
Bucket Size
(Cubic Meters)
Typical Digging
Reach (Meters)
Source: EPA, 1982
Typical Digging
Depth (Meters)
Drag-line crane unit
Backhoe
.8
1.3
1.5
.8
1.5
2.7
(1
(1
(2)
(1)
(2)
(3
cubic
yard)
3/4)
1/2)
14
17
21
11
15
21
(45 feet)
(57)
(68)
(35)
(49)
(70)
5
7
9
7
9
14
(16
(24)
(30)
(22)
(30)
(45)
feet)
Design Equations
The following two methods for designing excavation plans are
traditionally used:
Cross Sectional Method
Volume of material to be removed is calculated by aver-
aging the cross sectional area between successive cross
cuts (average end areas) and multiplying by the distance
between the cuts as follows (Davis, Foote, and Kelly,
1966):
v =
+ A2)
where :
V = volume of a section (ft3)
L = distance between end areas (ft)
2 = end cut cross sectional areas (ft2)
188
-------
TABLE 3-37
PRODUCTION RATES FOR EXCAVATION EQUIPMENT
Bucket Size Production Rate3
Excavation Equipment Soil Type (Cubic Meters) (Cubic Meters/Hour)
Drag-line crane unit Moist loam
Sandy clay 1.
Hard dense
Clay 1.
Backhoe Moist loam
Sandy clay 1.
Hard dense
Clay 1.
rj
based on typical operating conditions
8
5
8
5
8
5
8
5
(1 cubic 99 (130 cubic yard/hour)
yard)
(2)
(1)
(2)
(1)
(2)
(1)
(2)
168
69
122
65
134
50
99
(220)
(90)
(160)
(85)
(175)
(65)
(130)
Source: EPA, 1982
Formula is only exact when A^ = A2 but is generally a
good approximation when the two values are not equal.
A second cross-sectional formula is the prismodal for-
mula (Davis, Foote, and Kelly, 1966):
V = L/6 (A} + 4 Am + A2)
where:
V
L
AlfA2
A =
m
volume of a section (ft3)
distance between end areas (ft)
area of end cross section (ft2)
area of cross section midway between the
two ends (ft2)
Using the prismodal formula, Am is determined by aver-
aging the linear dimensions of the end cross sections.
2. Contour Method
189
-------
Volume calculation utilizes horizontal cross sections
taken directly from a contour map. The volume of a section
to be removed is calculated as follows (Smith, 1976):
V = CI (
where :
V = volume of earthwork (ft3)
CI = contour interval (ft)
ClfC2 = areas of adjacent closed contours (ft2)
If the contour interval CI is uniform throughout the
earthwork area, then the total volume can be calculated as
follows (Smith, 1976):
Ci CL
v = ci (— + c2 + c3 + . . . CL_I + —)
2 2
where:
V = total volume (ft )
G! = area of first contour (ft3)
C = area of last contour (ft2)
L
CI = contour interval
When contour information is available in sufficient detail, the
contour method is considered to be quicker, more versatile, and more
accurate than the cross-sectional method (Smith, 1976).
Special Precautions and Limitations
Field personnel must be protected from accidental exposure to
buried wastes.
190
-------
3.4.1.4 Principal Data Requirements
topography (volume)
accessibility of equipment (implementability and cost)
soil characteristics (equipment suitability)
• compaction
• strength properties (sufficient to support equip-
ment)
• depth
waste description (safety plan)
• chemical characteristics
• physical characteristics
• disposal practices
3.4.1.5 Elements of Cost Review
Components
Construction and Capital--
• excavation
• reburial
0 & M—
• transportation
Major Factors
• volume
* reburial location
191
-------
Data
Unit costs are presented in Table 3-38.
Costs for excavating and transporting 596,388 cubic meters of
waste and soil with reburial at a landfill 20 miles away is approxi-
mately $42 million.(1982 dollars). Ninety percent of this total is
due to reburial (tipping fees) at a secure landfill (SCS, 1980).
3.4.2 Drum Handling
3.4.2.1 Description
Drum handling addresses the handling and/or consolidation of
drummed waste before it is trucked to an off-site facility or stored
for on-site treatment. After excavation, drums are generally trans-
ported to an on-site staging area for processing and/or removal.
Waste samples are then taken and analyzed, and incompatible drums
are segregated to prevent accidents in the staging area. If a drum
is in poor condition, the contents are transferred to an alternate
drum or the drum is overpacked prior to transport. Pre-transport
consolidation of drummed liquid waste is achieved by pumping waste
from drums into a mixing tank or directly into a tank truck. Drummed
solids and sludges are generally consolidated in waste trailer
units. Empty drums are crushed and disposed of on or off-site.
3.4.2.2 Status
Conventional, demonstrated; but waste consolidation capabili-
ties will vary greatly from site to site.
3.4.2.3 Feasibility and Effectiveness
General Features
Careful drum handling is necessary whenever drummed waste is
found at a site. Transport of drummed waste in original,
overpacked, or alternate drums is most applicable when the number of
drums at the site is low. Pre-transport consolidation of waste is
most applicable when there is a large number of drums at a site in
poor condition, since the consolidation of large quantities of waste
192
-------
TABLE 3-38
UNIT COSTS FOR EXCAVATION
Excavation using
dragline
3/4 yd3 bucket, 90° swing,
Rating 35 yd3/hr
1.5 yd3 bucket, 90° swing,
Rating 65 yd3/hr
$2.62/yd~
$1.77/yd'
Excavation using
backhoe
Excavation using
clamshell
Hydraulic, crawler mounted „
1 yd3 bucket, rating 45 yd /hr
o 3
- 1.5 yd bucket, rating 60 yd /hr
o 3
2 yd bucket, rating 75 yd /hr
o 3
- 3.5 yd bucket, rating 150 yd /hr
Wheel mounted
o 3
- 0.75 yd bucket, rating 30 yd /hr
o 3
0.5 yd bucket, rating 20 yd /hr
o 3
1 yd bucket, rating 35 yd /hr
$2.26/yd~
$1.92/yd-
$2.02/yd-
$1.47/yd~
- 0.5 yd3 bucket, rating 20 yd /hr $4.11/yd~
$3.15/yd-
«-
$4.41/ydJ
$2.95/yd:
Source: EPA, 1982
can be more cost-effective than overpacking and transporting many
barrels.
Special Precautions and Limitations
Violent reaction and release of hazardous constituents of
reaction products is possible. It is, therefore, important that the
waste from each drum or drum lot be analyzed to prevent the mixing of
incompatible waste. A mixing tank can be used as a precaution to
prevent an accident once the waste is loaded into a tank truck.
193
-------
Compatibility of waste materials is a major concern in storing
and/or consolidating waste. To minimize risk of mixing incompatible
wastes, the following storage compatibility categories have been
developed by the US EPA Environmental Response Team (Turpin, et ai. ,
1981) :
• caustic (non-flammable)
• caustic (flammable)
• acid (non-flammable)
• acid (flammable)
• oxidizer (non-flammable)
• oxidizer (flammable)
• radioactive •
3.4.2.4 Principal Data Requirements
Waste Description (consolidation, safety) \
• flammability
• water reactivity
• redox potential
• volatility
• radioactivity
• physical characteristics
• drum location and condition
• waste compatibility for mixing
3.4.2.5 Elements of Cost Review
194
-------
Components
Construction and Capital--
• excavation
• mete red pumps
• mixers
• storage and consolidation tanks
0 & M--
• repacking of failed drums
Major Factors
• analysis of drum contents
• condition of drums
• quantity of waste
Data
Available cost data are limited. Costs reported for a New Jersey
storage site were 1.5 million dollars to remove 10,000 drums before
a fire at the site, and 17 million dollars to remove 25,000 drums (a
second contractor) after the fire (Finkel andd Golob, 1981). Analy-
sis costs for priority pollutants is on the order of $1, 000/sample.
3.4.3 Encapsulation
3.4.3.1 Description
Encapsulation is the process by which wastes are enclosed in a
stable, water resistant material. Wastes may be bound in a polymer
matrix prior to encapsulation. A typical process, developed by the
TRW Corporation (TRD 6), binds dried waste with 1, 2-polybutadiene
195
-------
(a polymer matrix) and then jackets it with a 1/4 inch-thick layer of
high density polyethylene. The encapsulated waste can then be land-
filled.
3.4.3.2 Status
Developmental for dried waste and drums; conceptual for
sludges.
3.4.3.3 Feasibility and Effectiveness
General
Encapsulated wastes provide stable containment for dried inor-
ganic wastes or secondary containment for drummed waste. The method
may be suitable for containing low volumes of toxic waste. However,
necessary equipment may not be suitable for transport to remedial
action sites.
Laboratory testing results indicate that for a finite period of
time encapsulated wastes have excellent mechanical, chemical and
biological integrity and are capable of withstanding impacts and
freeze-thaw stresses (EPA, 1982). Long-term integrity has yet to be
demonstrated. More detailed information is not available.
Special Precautions and Limitations
Not available.
3.4.3.4 Principal Data Requirements
• accessibility of equipment (implementibility, cost)
• waste description - organic or inorganic (feasibility,
applicability)
• types
• form - dried, sludge, drum
196
-------
3.4.3.5 Elements of Cost Review
Components
Construction and Capital--
• dewatering
• encapsulation equipment
landfill
O & M--
• volume
• physical characteristics of waste
Major Factors
• process development (status)
Data
None available.
3.4.4 Dewatering
3.4.4.1 Description
Dewatering can be either passive or active. Passive dewatering
techniques require no mechanical energy or additional thermal ener-
gy inputs for the removal of water. Water is removed through evapo-
ration and free (or gravity) drainage. For a discussion of active
dewatering, see "Filtration."
197
-------
3.4.4.2 Status
Conventional, demonstrated.
3.4.4.3 Feasibility and Effectiveness
General
Passive dewatering techniques are only applicable when the
material is free-draining, or when the evaporation potential at the
site is high. If toxic volatile compounds are present in the sludge,
escape of these compounds into the atmosphere should be considered.
Passive techniques include:
• Stockpiling. Material is placed in a drained area to allow
free drainage. Material can then be taken from the top of
the stockpile and spread in thin layers in a drying area to
allow the remaining water to evaporate (TRD 7) .
• Temporary sand-drying beds. Material is placed in small
diked containment areas with a surface layer of coarse sand
underlain by layers of graded gravel. The beds have an
earthen (preferably clay) bottom which slopes to under-
drains. Dewatering is by gravity drainage and evaporation
(EPA, 1982).
Special Precautions and Limitations
The feasibility of passive evaporative dewatering depends on
the evaporation potential at the site. The evaporation potential is
the maximum evaporation that can be expected under ideal conditions.
It is defined as the difference between the normal annual Class A pan
evaporation rate (found by standard testing) and the average annual
precipitation. A positive evaporation potential (e.g., 136
inches/year in the Sonora Desert represents a maximum value) indi-
cates significant solar evaporation and a suitability for passive
drying. A negative evaporation potential (e.g., -70 inches/year in
the Pacific Northwest Coast represents a minimum value) indicates
the-need for active dewatering techniques (TRD #7). Passive dewa-
tering may be possible in some areas with a negative evaporation
potential if the waste is covered. This strategy is employed for
sludge drying in the Northeast United States.
198
-------
3.4.4.4 Principal Data Requirements
Climatology (suitability of passive dewatering)
• precipitation
• evapotranspiration (normal annual Class A pan
evaporation rate)
• wind characteristics
• temperature
• exposure to direct sunlight
Waste Description (suitability for dewatering)
• water content
• sediment size
• thermal stability
• odor
• presence of volatile toxics
• drainage ability (free draining)
3.4.4.5 Elements of Cost Review
Components
Construction and Capital--
• excavation
O & M--
• none
199
-------
Major Factors
• volume
• excavation requirements
Data
None available.
3.5 AIR CONTROL TECHNOLOGIES
3.5.1 Pipe Vents
3.5.1.1 Description
A pipe vent is a vertical or lateral perforated pipe installed
at a site to collect gases or vapors. It is usually surrounded by
gravel to prevent clogging. Pipe vents can discharge to a treatment
system or directly to the atmosphere. Discharge can be natural (at-
mospheric) through either mushroom or "U" shaped tops, or forced by
means of a negative pressure fan. Pipe vents are used to prevent the
migration and release to the atmosphere of volatile toxics and other
dangerous gases. Typical pipe vent configurations are given in Fig-
ure 3-23 .
3.5.1.2 Status
Conventional, undemonstrated. Pipe vents have been used prima-
rily in the control of methane at municipal landfills. Application
to uncontrolled hazardous waste sites has been extremely limited and
technology effectiveness is unclear.
3.5.1.3 Feasibility and Effectiveness
Construction (EPA, 1982)
Pipe vents are constructed in the same manner as groundwater
monitoring well.
200
-------
FIGURE 3-23
DESIGN CONFIGURATION OF PIPE VENTS
(Source: EPA, 1982)
r-o
o
To atmosphere
or treatment
Low permeability
soil
4-6" slotted
PVC pipe
Gravel
(a) Atmospheric
vent
Mushroom Top
(b) Atmospheric
vent
"U" Top
(c) Forced
Ventilation
To treatment
(d) Vertical pipe vents connected to forced
ventilation manifold system
-------
Pipe vents may be installed with a gravel pack to prevent clog-
ging, although there is some debate as to whether this is necessary
(Rovers, et al., 1978). The gravel pack should be sealed from the
atmosphere with cement, cement/soil grout, or clay.
Vent depth should extend to the bottom of the fill or contam-
inated material, but not below the water table or into liquid waste.
Vents will be more effective when used in conjunction with a
surface seal to prevent uncontrolled gas release.
Vent Placement
Atmospheric vents should be placed at contours of maximum gas
concentration, (determined by a gas probe).
Spacing of forced vents depends on the radius of influence of
the pipe (discussed below) . Test drawdowns to measure head loss as a
function of distance from the vent, at various pumping rates may be
performed to determine spacing at a specific site.
Typical vent spacing is 17 meters (56 ft) .
Radius of Influence
Radius of influence of a forced vent depends on pipe character-
istics:
• pumping rate;
• intake depth; and
• pipe diameter.
Site characteristics:
• cover material;
• depth of fill; and
202
-------
soil permeability.
Figure 3-24 shows how the radius of influence varies with pump-
ing rate and depth of intake.
Selection of Vent Type
The decision of whether to use forced or atmospheric venti-
lation depends on vapor flux (the amount of gas migrating to the
air) . If the rate of vapor flux is higher than can be safely vented
to the atmosphere, forced ventilation may be required. The follow-
ing equations can be used for determining vapor flux:
1 O/ 3 2
J = Do (Pa /Pt ) (°2 ~ Cs)/L
where:
J = vapor flux from soil surface (ng/cm2/day)
DQ = vapor diffusion coefficient of volatilizing
material
?a = soil air-filled porosity (cm3/cm3)
P = total soil porosity (cm3/cm3)
C = concentration of the volatilizing material
at the surface of the soil (yg/1)
Cg = concentration of the volatilizing material
at the bottom of soil layer (yg/1)
L = soil depth (cm)
and:
Co = pm/RT
s
where:
p = vapor pressure of volatilizing material (mm Hg)
m = molecular weight of a compound (g/mole)
o
R = molar gas constant(mm Hg/ K mole)
T = absolute temperature (°K)
203
-------
FIGURE 3-24
RADIUS OF INFLUENCE OF PIPE VENT
(for one inch water pressure at different withdrawal rates)
(Source: Carlson, 197?)
Top of Landfill
Si
o
o>
V
-------
If the diffusion coefficient is not known for a given substance
or at a given temperature, it can be estimated (assuming that the
vapor pressures for substances A and B are low) by the following
equations:
where:
D = diffusion coefficient of substance A
M = molecular weight of substance A
D = diffusion coefficient of substance A
B
M = molecular weight of substance B
and:
D2 = D1(T2/T1) V2
where T = absolute temperature (°K).
More rigorous equations for estimating diffusivity are given in
Shen and Toffelmire, 1980 and Thibodeaux, 1979.
Special Precautions and Limitations
None.
3.5.1.4 Principal Data Requirements
Soil characteristics (radius of influence, vapor flux)
• permeability
• porosity - air-filled and total
• depth
Temperature (vapor flux)
Depth to water table (vent placement)
205
-------
Waste description
• physical characteristics
• disposal practices
Gas concentrations (vent placement)
Cover characteristics (vent placement, radius of
influence)
Vapor flux (vent type: forced or atmospheric)
3.5.1.5 Elements of Cost Review
Components
Construction and Capital--
• piping and laterals
• installation
• fan (for forced system)
O <& M--
• power for forced system
• monitoring
Major Factors
• number and size of pipes
• length and size of laterals
• type of system (forced or atmospheric)
206
-------
Data
Unit costs asociated with pipe vents are given in Table 3-39.
Total costs for a forced pipe vent system at a disposal site are
given in Table 3-40.
3.5.2 Trench Vents
3.5.2.1 Description
A trench vent is a narrow trench backfilled with gravel forming
a path of least resistance through which gases migrate upward to the
atmosphere or to a collection manifold. These vents typically sur-
round the waste site or span a section of the perimeter of the waste
site. By diverting the flow in this way, the trench vents form a
barrier against lateral migration of methane or toxic vapors.
Trench vents are often lined on one side to form an effective barrier
against gas migration. They can be open or capped with clay and fit-
ted with collection laterals and riser pipes vented into the
atmosphere. They can also be connected to a negative pressure fan or
blower. Various configurations of trench vents are shown in Figure
3-25.
3.5.2.2 Status
Conventional, undemonstrated. Trench vents have been used pri-
marily in the control of methane at municipal landfills. Applica-
tion to uncontrolled hazardous waste sites has been extremely
limited and technology effectiveness is unclear.
3.5.2.3 Feasibility and Effectiveness
Construction
Maximum trench depth is 3 meters (10 ft) (EPA, 1982) .
Trench performance can be enhanced by:
207
-------
TABLE 3-39
UNII COSTS OF PIPE VENT COMPONENTS
Fans (a)
Flow Rate
Total Installed
Cost (1982 dollars)
Annual Operating
Cost (1982 dollars)
0-136 @ 3" H20
135-600 @8" H20
500-2000 @ 8" H20
1900-6000 @ 8" H20
Pipe
PVC
Asbestos Bonded
Galvanized Iron
Elbows
PVC
Galvanized Iron
ABS
Tees
PVC
Galvanized Iron
ABS
Butterfly Valves
Cast Iron
PVC
Flow Meters
689 8.
1,568 - 1,641 60 - 390
2,128 - 2,296 60 - 1,314
4,676 - 5,225 190 - 3,940
Total Installed Costs ($/ft)
4"
15.19
1.64
22.00
6"
21.09
2.19
43.10
8"
—
3.36
56.60
10"
—
5.12
75.00
22.20 46.90 82.30 163.50
38.10 87.00 160.40 234.10
19.10 30.60 38.80 93.30
31.40 58.50 119.50 239.70
60.00 136.90 267.80 451.00
19.10 30.60 42.40 93.10
326.00 479.70 725.70 1039.40
162.40 268.80 425.60 560.00
996.30 1254.60 1445.30
Belt-driven, utility mount, weather cover, and corrosion resistant coating.
3 Cost = Fan Brake HP x 0.746 KW 8760 hr $0.04
HP X yr KW-hr
Source: EPA, 1982
208
-------
TABLE 3-40
COSTS FOR A FORCED PIPE VENT SYSTEM
Basis: - A collection system in which a blower is connected to pipe
vents.
- All manifold components are sized for 0.15 m (6 in) piping
diameters.
- Costs include installation.
Capital Costs
Blower 1,250 cfm (2 hp)
PVC Pipe: Risers (300 m) 4 in.
Laterals (910 m) 8 in.
PVC Pipe Tees 8 in. (25)
Butterfly Valves 8 in. (5)
Flow Meter 8 in. (1)
PVC Pipe Elbows 8 in. (25)
Moisture Traps (10)
Monitoring Program
Monitoring Equipment
Monitoring Wells, Gas (32)
Capital Costs (subtotal)
Overhead Allowance (25 percent)
Contingency Allowance (30 percent)
Total Capital Costs
Total Unit $
Lower U.S.
1,240
7,020
43,400
2,650
1,190
730
1,880
3,760
560
850
63,280
15,820
18,980
98,080
(1982 dollars)
Upper U.S.
2,090
12,950
75,130
4,390
2,020
1,520
2,830
6,380
560
1,680
109,550
27,390
32.870
169,810
O&M Costs
Monitoring
24 hr per time, 24 times
per year (96 hr/yr) (labor costs) 890
Power Cost
1.5 kWh i§2 hp = 12,900 kWh/yr
(0.04/kWh) (8,600 hr/yr operation) 520
Operating Cost
40 hr/mo (480 hr/yr 5,950
Total O&M Costs 7,360
1,870
520
12.,-340
14,730
Source: SCS, 1981
209
-------
FIGURE 3-25
DESIGN CONFIGURATION OF TRENCH VENTS
(Source: EPA, 1982)
Gravel pack
(a) Open Trench
(b) Open Trench with Liner
Gravel pack
Side View Front View
(c) Closed Trench with Lateral and Risers
(d) Induced Draft
(e) Air Injection
210
-------
• lining one side of the trench with an impermeable barrier to
prevent migration through and past the trench;
• extending trenches to form a continuous seal with groundwa-
ter or impermeable stratum to prevent migration underneath
the trench;
• installing laterals and riser pipes to facilitate gas move-
ment. A typical riser spacing is 15 meters (49 ft); and
• covering the site with a surface seal to increase the effec-
tiveness of the trench as the path of least resistance.
Selection of Vent Type
The equation for determining vapor flux are given in the dis-
cussion of pipe vents.
Special Precautions and Limitations
Trenches should not be located in an area of low relief to pre-
vent water infiltration and clogging with solids. A slope can be
constructed along the trench to keep runoff from infiltrating. This
is of particular importance for trench vents which are not capped
but open to the atmosphere.
3.5.2.4 Principal Data Requirements
Topography (vent placement)
Soil characteristics (radius of influence, vapor flux)
• permeability
• porosity (air-filled and total)
• depth
Temperature (vapor flux)
Depth to water table (vent placement)
Waste description (vent placement)
• physical characteristics
211
-------
• disposal practices
Gas concentrations (vent placement)
Cover characteristics (vent placement, radius of
influence)
Vapor flux (vent type: forced or atmospheric)
3.5.2.5 Elements of Cost Review
Components
Construction and Capital--
• trench excavation
• liner
• laterals and riser pipes
• gravel
• backfill
• blower (for forced system)
0 & M--
*- power for blower
• monitoring
Major Factors
• number, length and depth of trenches
• length and size of laterals and riser pipes
• type of system (forced or atmospheric)
• liner material
212
-------
Data
Unit costs associated with trench vents are given in Table 3-41,
Total cost for a trench vent system are given in Table 3-42.
TABLE 3-41
UNIT COSTS FOR TRENCH UNITS
Basics
Costs (1982 dollars)
Trench excavation
Spread excavated
material
Well-point
dewatering
Gravel
20' deep, 4' wide,
by backhoe
$1.27/cubic yard
Spread nearby and grade $0.84/cubic yard
and cover trench
500' header, 8" diameter, $95/linear foot
for one month
Buy and haul from pit $9.65/cubic yard
2 miles, backfill with
dozer
Sheet piling
Walers, connections,
struts
Lateral with risers
Liner
Pull and salvage
2/3 salvage
$7.24/square foot
$130/ton2
12" corrugated poly- $8.26/linear fo°t
ethylene lateral, 6" PVC
risers, 15' long every
50'. 500' lateral
Hypalon (36 mil) $2.35 - 3.36/square
Bracketed with heavy- foot
weight geotextile fabric
4" gunite layer with
mesh
$5.88 -10.67/square
foot
Source: EPA, 1982
213
-------
TABLE 3-42
COSTS UF TRENCH VENTS FOR A DISPOSAL SITE
Basis: - Use of lateral risers and a synthetic liner.
- Well point dewatering done for one month.
- Laterals with risers: Laterals 0.3 m (12 in) PVC;
risers 0.15 m (6 in) PVC pipe by 7 m long, placed
every 15 m along the lateral.
- Liner consists of hypalon (36 mil) bracketed with
heavyweight geotextile fabric.
Total Unit Cost (1982 dollars)
Capital Costs Lower U.S. Upper U.S.
Trench Excavation (4,255 m )
935 m (L) x 3.5 m (d) x 1.3 m (w) 6,850 7,790
3
Spread Excavated Material (2,850 a ) 2,200 2,600
Gravel (2,850 m3) 22,690 35,030
Pipe, PVC: 12" Lateral (950 m)
Riser Pipe, 6" (450 m) 137,600 195,630
Liner (5,700 m ) 30,030 50,830
Backfill (1,405 in3) 2,990 3,580
Monitoring Program
Monitoring Equipment 600 600
Monitoring Wells, Gas (32)
(1/2" PVC, 3.6 m deep) 920 1,800
Capital Costs (subtotal) 203,880 297,860
Overhead Allowance (25 percent) 50,970 74,470
Contingency Allowance (20 percent) 40^780 59,570
Total Capital Costs 295,630 431,900
O&M Costs
Monitoring
24 tiines/yr (4 hr/time) 880 1,870
(96 hr/yr)(labor costs)
Source: SCS, 1981
214
-------
SECTION 4
TREATMENT TECHNOLOGIES
4.1 INTRODUCTION
This section contains discussions of individual or groups of
closely related leachate treatment technologies. Each discussion
follows the format described in Section 1.
The selection of treatment technologies depends in part on the
chemical nature of the leachates or wastes being treated as well as
on many other factors. Table 4-1 displays the relative treatability
of 17 classes of hazardous constituents by the various technologies
described in this Section. As an example of the treatability of haz-
ardous waste leachates, Table 4-2 classifies EPA's 129 priority
pollutants into the 17 classes. Table 4-1 can be used to suggest
which treatment technologies may be appropriate for leachates con-
taining these pollutants.
In addition, Table 4-3 summarizes the many data requirements
common to the treatment technologies. The individual technology
discussions may expand on this table or incorporate additional data
needs.
4.2 BIOLOGICAL TREATMENT
4.2.1 Activated Sludge
4.2.1.1 Description
In the activated sludge process bacteria breaks down organic
wastes in aqueous streams by oxidation and hydrolysis in the pres-
ence of oxygen (aerobically) . The microorganisms become acclimated
215
-------
TABLE 4-1
TREATMENT PROCESS APPLICABILITY MATRIX
TREATMENT TECHNOLOGY
Biological Treatment
Activated Sludge
Rotating Biological Disc
Trickling Filter
Surface Impoundment
Land Treatment
Chemical Treatment
Chemical Oxidation
Alkaline Chlorlnation
Ozonatlon
Chemical Reduction
Neutralization
Precipitation
Ion Exchange
Wet Air Oxidation
Physical Treatment
Carhon Adsorption
Density Separation
Sedimentation
Flotation
Filtration
Reverse Osmosis
Stripping
Enua 11 zat Ion/Detent Ion
In-Sltu Treatment
Biological Methods
Chemical Methods
tn
s
o
o
^
E
E
E
E
E
E
E
E
N
3,E
N
-
X
V
V
-
X
tn
.a
u
s
a.
**J
V
V
V
V
V
V
V
V
N
P
N
-
X
V
V
-
X
tn
tj
^!
V
V
V
V
V
V
V
V
N
N
N
-
X
V
-
X
tn
u
•H
U
g
«fl
V
V
V
V
V
V
V
V
N
-,G
N
-
F
X
G,E
V
-
X
tn
n) o
o
N
N
N
N
N
N
N
N
N
N
N
-
N
E
N
N
E
N
-
0)
^
g,
H)
3 V)
V) Tj
n] o
O
-
X
X
_
«-t
o
c
It
at
M
-
X
-
KEY
E •=> Excellent Performance I.lkrly
G = Good Performance I.lkely
F * Fair Performance I.lkelv
P = Foot Performance l.lkely
R " Kcporrrd to !»• Removed
N •> No( Applicable
V = Variable Performance Report etl
for Different Compounds In
the Class
X - Treatment t.q Applicable hnl
Not Specified In the Source
Reference
- A Illank liulli-Htes Nti Data
Available
Source: TRD 5
NJ
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS
NAME
TREATABILITY CLASS
SYNONYMS
N>
Acenaphthene
Acenaphthylene
Acrolein
Acrylonitrile
Aldrin
Anthracene
Antimony
Arsenic
Asbestos
Beryllium
Benzene
Benzldine
Benzo (a) Anthracene
3,4-Benzofluoranthane
Benzo (k) Fluoranthane
Benzo (ghl) Perylene
Benzo (e) Pyrene
e-BHC-Alpha
b-BHC-Beta
r-BHC (Lindane)-Gamma
g-BHC-Delta
bis(2-chloroethoxy)Methane
Aromatics
Aromatlcs
Misc.
Misc.
Pesticides
Aromatics
Metals
Metals
Misc.
Metals
Aromatics
Substitute Aromatics
Aromatics
Aromatics
Aromatics
Aromatics
Aromatics
Pesticides
Pesticides
Pesticides
Pesticides
Chlorinated Ethers
1,2-Dihydroacenaphthylene
2 Propenal
2 PropenenitriJe
Stibium
Amianthus
Benzol
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS (Cont.)
NAME
TREATABILITY CLASS
SYNONYMS
OO
bis(2-chloromethyl)Ether
bis(Chloromethyl)Ether
bis(2-Chlorolsopropyl)Ether
bis(2-Ethylaxyl)Phthalate
Sromoform
4-Bromophenyl Phenyl Ether
Butyl Benzyl Phthalate
Cadmium
Carbon Tetrachloride
Chlordane
Chlorobenzene
Chlorodibromomethane
Chloroethane
2-Chloroethyl Vinyl Ether
Chloroform
2-Chlorophenol
4-Chlorophenyl Phenyl Ether
2-Chlorophythalene
Chromium
Chrysene
Copper
Cyanide
4,4-DDD
Chlorinated Ethers
Chlorinated Ethers
Chlorinated Ethers
Phthalate Esters
Chlorinated Alkanes
Chlorinated Ethers
Phthalate Esters
Metals
Chlorinated Alkanes
Pesticides
Chlorinated Aromatics
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Ethers
Chlorinated Alkanes
Phenols
Chlorinated Ethers
Chlorinated Aromatics
Metals
Aromatics
Metals
Miscellaneous
Pesticides
Tr ib r omome thane
Tetrachloromethane
Monochlorobenzene
(2-Chloroethoxy)Ethane
Trichloromethane
1,2-Benzphenanthrene
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS (Cont.)
NAME
TREATABILITY CLASS
SYNONYMS
ro
4,4-DDE
4,4-DDT
Dibenzo (a,h)Anthracene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
3,3-Dichlorobenzidene
Dichlorbromothane
Dichlorodifluromethane
1,1-Dichloroethane
1,2-Dichloroethane
1,1-Dichloroethylene
2,4-Dichloro Phenol
1,2-Dichloropropane
1,2-Dichloropropylene
Dieldrin
Diethyl Phthalate
2,4-Dimethyl Phenol
Dimethyl Phthalate
Di-N-Butyl Phthalate
4,6-Dinitro-O-Cresol
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6 Dinitrotoluene
Pesticides
Pesticides
Chlorinated Aromatics
Chlorinated Aromatics
Chlorinated Aromatics
Substituted Aromatics
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Phenols
Chlorinated Alkanes
Chlorinated Alkanes
Pesticides
Phthalate Esters
Phenols
Phthalate Esters
Phthalate Esters
Phenols
Phenols
Substituted Aromatics
Substituted Aromatics
1,2-Benzenedicarboxylic Acid
2-Methyl-4, 6-Dinitrophenol
Aldifen
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS (Cont.)
NAME
TREATABILITY CLASS
SYNONYMS
fo
N>
o
Di-N-Octyl Phthalate
1,2-Diphenyl Hydrazine
A-Endosulfan-Alpha
B-Endosulfan-Beta
Endosulfan Sulfate
Endrin
Endrin Aldehyde
Ethylbenzene
Fluoranthene
Fluorene
Haphthalene
Heptachlor
Heptachlor Epoxide
Hexachlorobenzene
Hexachlorobutadiene
Hexachloroeyclopentadiene
Hexachloroethane
Indeno (1,2,3-c,d)Pyrene
Isophorone
Lead
Mercury
Phthalate Esters
Substituted Aromatics
Pesticide
Pesticide
Pesticide
Pesticide
Pesticide
Aromatics
Aromatics
Aromatics
Aromatics
Pesticides
Pesticides
Chlorinated Aromatics
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Aromatics
Miscellaneous
Metals
Metals
Perchlorobenzene
Hydrargyrum
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS (Cont.)
NAME
TREATABILITY CLASS
SYNONYMS
Methyl Bromide
Methyl Chloride
Methylene Chloride
Nickel
Nitrobenzene
2-Nitrophenol
A-Nitrophenol
N-Nitrosodimethylamine
N-Nitrosodi-N-propylamine
N-Nitrosodiphenylamine
Para-Chloro-Meta-Cresol
PCB-1016
PCB-1221
PCB-1232
PCB-1242
PCB-1248
PCB-1254
PCB-1260
Pentachlorophenol
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Metals
Substituted Aromatics
Phenols
Phenols
Miscellaneous
Miscellaneous
Miscellaneous
Phenols
Polychlorinated
Biphenyls
Phenols
Bromomethane;
Monobromomethane;
Embafume
Chloromethane
Dichloromethane
Nitrobenzol
Nitrobenzol
Penta; PCP; Penchloro;
Santophen
-------
TABLE 4-2
TREATABILITY CLASSIFICATION OF THE 129 PRIORITY POLLUTANTS (Cont.)
NAME
TREATABILITY CLASS
SYNONYMS
ho
ho
Phenanthane
Phenol
Pyrene
Selenium
Silver
2,3,7,8-Tetrachlorodlbenzo-
P-Dioxin
1,1,2,2-Tetrachloroethane
Tetrachloroethylene
Thallium
Toluene
1,2-Trans-Dichloroethylene
1,2,4-Trichlorobenzene
1,1-Trichloroethane
1,1,2-Trichloroethane
Trichloroethylene
Trichlorofluoromethane
2,4,6-Trichlorophenol
Vinyl Chloride
Zinc
Aromatics
Phenols
Aromatics
Metals
Metals
Chlorinated Alkanes
Chlorinated Alkanes
Metals
Aromatics
Chlorinated Alkanes
Chlorinated Aromatics
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Chlorinated Alkanes
Phenols
Chlorinated Phenols
Metals
Carbolic Acid; Phenic Acid
Benzo(def)Phenanthrene
Perchlorothylene; Ethylene
Tetrachloride
Methylbenzene
Vinyl Trichloride
Trichloroethene; Ethinyl
Trichloride
Fluorotrichloromethane
Dowicide 25; Omal
Chloroethylene
Source: TRD 5
-------
TABLE 4-3
TREATMENT TECHNOLOGY DATA REQUIREMENTS
TREATMENT
TECHNOLOGY
Biological Treatment
Activated Sludge
Rotating Biological Disc
Trickling Filter
Surface Impoundment
Land Treatment
Chemical Treatment
Chemical Oxidation
Alkaline Chlorination
Ozonation
Chemical Reduction
Neutralization
Precipitation
Ion Exchange
Wet Air Oxidation
Physical Treatment
Carbon Adsorption
Density Separation
Sedimentation
Flotation
Filtration
Reverse Osmosis
Stripping
Equalization/Dentention
In-Situ Treatment
Biological Methods
Chemical Methods
1 Volume
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
z
H
X
X
X
X
X
1
U.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
a.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
i
1
'5
UI
£
1
a
X
UI
=3
2
X
X
X
X
X
X
X
8
X
X
X
X
X
X
§
u
• x
X
X
X
X
X
g
X
X
X
X
X
X
X
X
I
X
X
X
X
X
X
X
X
X
X
X
X
2
X
X
X
X
vt
X
X
X
X
X
X
X
X
X
Cyanide
X
X
X
X
X
X
X
X
Temperature
X
X
X
X
X
X
»
1
Complexing
X
Viscosity
X
X
Climate
X
X
X
X
X
X
X
£
•x
Soil Permeat
X
X
X
Soil CEC
X
X
X
•c
8
0
a.
0
O
i
Oxidation R
£
15
(D
'w
Leachate Va
X
X
X
X
X
X
X
X
i
u
Phosphorus '
X
X
X
X.
X
*
l
1
1
3
'o
Particle Size
X
X
X
$
8
a
U)
'i
S
Presence of
X
X
X
X
X
X
X
X
X
X
X
X
X
X
ro
M
uo
-------
to the wastewater environment through continuous recycle as shown in
Figure 4-1.
A sludge residue is generated along with the treated effluent.
As shown, the operation includes an aeration basin, a clarifier, and
provisions for returning a portion of the sludge from the clarifier
to the aeration basin. Aeration systems typically release air into
the system, but pure oxygen may also be used. Generally, equaliza-
tion, neutralization, and/or primary sedimentation precede
activated sludge processing. Disposal options for the sludge
include landfill, incineration, and land application.
4.2.1.2 Status
Conventional, demonstrated. Existing activated sludge treat-
ment plants have been used to treat leachate from hazardous waste
facilities.
4.2.1.3 Feasibility and Effectiveness
Performance of an activated sludge treatment system is typified
by BOD removal efficiency. In hazardous waste applications removal
efficiency of specific compounds or classes of compounds may be a
more important measure of performance. The mean BOD removal effi-
ciency for 92 industrial wastewater streams which were studied by
the USEPA was 86 percent EPA, 1980) . The mean influent and effluent
BOD levels were 1310 and 184 mg/1 respectvely. Units are typically
designed to remove 85 to 95 percent of a wastewater BOD load and are
capable of treating BOD levels up to 10,000 mg/1.
Performance depends primarily on the type of organics present
(see treatability summary), type of aeration, and retention time.
Aeration methods are summarized in Table 4-4.
For effective operation, influent to an activated sludge system
must be at a pH level near neutral, and process loading must be con-
sistent. Usually an equalization tank and a pH adjustment system
are pretreatment steps.
4.2.1.4 Design Basis
Kev design parameters are (Adams and Eckenfelder, 1974):
224
-------
FIGURE 4-1
TYPICAL ACTIVATED SLUDGE SYSTEM
(Source: ADL, 1976)
Wastewater .
Influent A """
ho
to
Aerator
Recycled Sludge
Wastewater Effluent
Sludge Residue
-------
TABLE 4-4
SUMMARY OF AERATION METHODS
Method
Description
Application
Extended Aeration
Longer wastewater
retention times in the
aeration basin.
Low organic loading and
reduced sludge quantities
desired.
Pure Oxygen
Aeration
Wastewater aeration with
pure oxygen in a closed
aeration tank.
High organic and/or
metal loading.
Contact
Stabilization
Aeration of recycled
sludge on its return to
the aeration tank.
Sludge removes BOD
rapidly by biosorption.
Contact stabilization
decomposes the sorbed
organics.
BOD removal rate, Sr (primary design target)
Sr = (SQ -
(8.34)Q
Where:
S = influent total BOD (mg/1)
S = target effluent soluble BOD (mg/1)
Q = average flow (mgd)
Detention time
Detention time is the longer of the following two cal-
culations, depending on the controlling mechanism:
S (S -S )
t = ° °—— (BOD is the controlling factor)
KXvSe
t =
(X )(F/M)
(F/M is the controlling factor)
226
-------
where:
K - removal rate coefficient (I/day)
Xv = average mixed liquor volatile suspended
solids (MLVSS)
F/M = food to microorganism ratio (lb organics/lb
MLVSS/day), obtained by laboratory tests
as shown below
Oxygen requirements should be calculated based on sum-
mer operating conditions when oxygen demand is usually
highest and transfer efficiency lowest. The oxygen
requirement equation is:
Rr = a'
-------
ctGT -20
w
L\ » /
where:
NQ = standard oxygen transfer efficiency at 20°C,
standard pressure for tap water containing
no oxygen (Ib 02/(hr)hp)
B = ratio of dissolved oxygen in a saturated
waste solution to that in tap water (usually
.92-.98)
C = dissolved oxygen saturation concentration in
waste (mg/1)
CL = design dissolved oxygen concentration (mg/1)
C = dissolved oxygen concentration in pure water
at 20% and standard pressure (mg/1)
a = ratio of oxygen transfer rate in waste to
that in pure water
0 = temperature coefficient (1.02 for diffused
aeration, 1.028 and for surface aeration)
T = aeration basin temperature (°C)
Horsepower requirements can also be estimated from the follow-
ing rough relationship:
BOD removed per day
hp =
45 Ib BOD removed per hp-day
A minimum of 100 hp per mgd is required to insure solid suspen-
sion in the reactor tank.Food to microorganism ratio (F/M)
Food is the biodegradable portion of the leachate. There is a
particular F/M ratio at which settleability is optimum. This opti-
mum ratio must be determined experimentally by measuring both
effluent suspended solids and zone-settling velocity as a function
of F/M and plotting the results on a single graph (Adams and Ecken-
felder, 1974). This value is used in the design, unless BOD controls
retention time (see above), in which case:
228
-------
s
F/M = 0_
Clarifier design
Clarifier design depends either on the hydraulic load-
ing or on the solids flux. Design surface area (A) for the
clarifer should be the larger of the areas given by the fol-
lowing equations (Adams and Eckenfelder, 1979):
O.K.
A = (Q + R) 8.34 Xv
solids flux
Where:
O.K. = K(ZSV)(Fc)
and:
Q1 = flow (gpd)
Q2 = flow (mgd)
2
O.K. = clarifier overflow rate (gpd/ft )
R = sludge recycle rate (mgd)
Xv = average aeration basin MLVSS (mg/1)
2
solids flux = solids loading (lb/ft /day)
K = constant (180(gpd/ft2)/(ft/hr))
ZSV = zone settling velocity (ft/hr)
Fc = scale up factor
Nutrient requirements
Activated sludge requires phosphorus and nitrogen
nutrients, to sustain biological activity. Nutrient
requirements are calculated as follows (Adams and Ecken-
felder, 1974):
229
-------
ni_ . 0.123 XAX (0.77-X)AX
Ib Nitrogen required/day = v + Q.07 Y.
0.// 0.77
0.026XAX (0.77-X)AX
Ib Phosphorous required/day = v + Q. 01
0.77 ' W'WJ- 0.77
where:
X = biodegradable fraction of MLVSS
Nitrogen and phosphorus in the influent can provide
some of the nutrient requirements.
• Sludge production can be calculated by (Adams and Ecken-
felder, 1974):
Total Sludge = f X. + AX - X
i v e
where:
f = nonbiodegradable fraction of the influent
suspended solids
X. = influent suspended solids (Ib/day)
AX = excess biological sludge production (Ib/day)
X = effluent suspended solids (Ib/day)
Special Precautions and Limitations
Some heavy metals and some organics at concentration above a few
ppm are toxic to activated sludge organisms. (See EPA, 1982 for
threshold toxicity concentrations for some metals.) If toxic spe-
cies are present in sufficiently high concentrations, pre-treatment
process must be incorporated into the treatment flow to remove them.
Activated sludge may have difficulty in removing refractory organ-
ics (i.e., highly chlorinated organics) from wastewater.
4.2.1.5 Principal Data Requirements
Kinetic parameters (treatability, see Adams & Eckenfelder,
230
-------
1974)
• specific BOD reaction rate coefficient (for retention time)
• oxygen coefficients (for oxygen requirements)
• sludge coefficients (biodegradable fraction)
• biodegradable sludge fraction (nutrient requirements)
• oxygen transfer coefficient (horsepower)
• standard oxygen transfer efficiency (horsepower)
• oxygen saturation coefficient (horsepower)
• temperature correction coefficient (retention time, horse-
power)
Average and maximum influent flow (retention time)
Influent temperature (horsepower)
Ambient extreme ambient temperature, summer and winter
(horsepower)
Average and maximum influent BOD (retention time)
Influent suspended solids (sludge production)
Non-biodegradable fraction of influent solids (sludge pro-
duction)
Influent nitrogen and phosphorous (nutrient requirements)
Average MLVSS - generally assumed to be between 2,000 and
4,000(retention time)
4.2.1.6 Elements of Cost Review
Components
Construction and Capital--
• excavation
231
-------
• tanks
• pumps
• clarifier
• aeration equipment
0 & M--
• chemicals
• electricity
• solids disposal
Major Factors
• process size
• aeration requirements
• detention time
Data
A unit cost example is presented in Table 4-5.
4.2.2 Surface Impoundments
4.2.2.1 Description
Surface impoundments (also called lagoons) are systems in which
the processes of microbial oxidation, photosynthesis, and sometimes
anaerobic digestion combine to breakdown hazardous organic com-
pounds. They are similar to activated sludge units without sludge
recycle. Aeration may be supplied passively by wind and algae or, in
aerated surface impoundments, by mechanical aerators. The oxygen
introduced by aeration is used by the bacteria to oxidize organic
matter to carbon monoxide (C02) ; the algae use the CO2 for photosyn-
thesis and produce more oxygeru The ecology of surface impoundments
closely resembles a natural eutrophic lake, a more complex system
than other biological treatment systems. A secondary benefit of
232
-------
LO
to
TABLE 4-5
ESTIMATED UNIT COSTS OF ACTIVATED SLUDGE SYSTEMS
Activated Sludge
Basis: 1x10 gallons/day, 10,000 ppm COD, 4,000 ppm BOD, 6,000 ppm
MLVSS, 365 day/year operation/sludge management costs not included
Estimated Capital Investment: $3,078,000
Annual
Quantity
Variable Costs
Operating Labor 8,760 MH
Maintenance (4% of InvJ
Quick-Lime 400 tons
Ammonia 330 tons
Phosphoric Acid 180 tons
Electricity 5.3xlQ6kWh
Total Variable Costs
Fixed Costs
Taxes and Insurance (2% of Inv.)
Capital Recovery (10 Years @ 10%)
Total Fixed Costs
Total Costs
Unit Cost ($/103 gal)
Cost Per Unit
Quantity, 1982 $
19.60/MH
31.00/ton
210.00/ton
520. OO/ ton
.04/kWh
Annual Cost,
1982 $
171,700
123,120
12,400
69,300
93,600
212,000
682,100
61,560
503,820
565,380
1,247,500
3.42
Source: ADL, 1976
-------
surface impoundments is clarification. Physical and chemical
treatment processes may also be carried out in surface impoundments.
Figure 4-2 shows a flow diagram of an aerated impoundment, with
a secondary clarifier. A separate clarifier may not be required
with other impoundment designs, e.g., facultative impoundments, if
the design includes a separate baffled settling compartment, two or
more impoundments in series, or other special features.
4.2.2.2 Status
Conventional, demonstrated.
4.2.2.3 Feasibility and Effectiveness
General Features
The types of surface impoundments most commonly used are as fol-
lows:
Type
• Aerated Impoundment
Facultative
Impoundment
Waste Stabilization
Ponds (Aerobic
Surface Impoundments)
Description
Mechanical or diffused aeration
using impoundments 1.8-6.1 m deep.
Forced flow in oxidation ditch
an alternative. Only aerobic
action allowed. Usually
requires a separate clarifier.
No forced aeration. Degradation
is via both aerobic (near sur-
face) and anaerobic (near bottom)
processes. Depths are typically
.6-1.5 m.
No forced aeration, however,
impoundment is kept aerobic by
natural processes (wind, algal
activity). Depth is generally
. 3-.6 m.
234
-rjf
-------
FIGURE 4-2
AERATED SURFACE IMPOUNDMENT
(Polymeric Lined Earth Construction)
(Source: ADL, 1976)
Nutrient Feed
u>
Ul
Mechanical Aerators
(optional)
Liquid Effluent
Secondary Clarifiers
(Concrete)
Excess Sludge
-------
Anaerobic Surface Impoundment uses a lower surface-
Impoundments to-volume ratio to increase the
anaerobic action. This allows
(and requires) higher organic
loadings than with other types.
Less sludge is generated. Oper-
ating Temperatures above ambient
(^25-30°C) are usually required.
Surface impoundments can normally handle BOD levels of 200-500
mg/1; anaerobic systems can tolerate somewhat higher levels. For
wastes with BOD levels in this range and with suspended solids less
than 0.1 percent, impoundments may be used as the primary method of
BOD removal. Removal efficiencies for BOD are usually in the range
of 60-90 percent. More often, impoundments are used to polish low
BOD content effluent from activated sludge or trickling filters pri-
or to discharge.
High performance has been demonstrated for (TRD 5):
• alcohol
• amines
• cyanides
• phenols
• phthaiates
Variable performance has been observed for (TRD 5):
• aliphatics
• amines
• aromatics
Poor performance has been observed for (TRD 5):
• halocarbons
• metals
• pesticides
236
-------
• polynuclear aromatics (PNA)
Surface impoundments are unsuited for (TRD 5)
• total dissolved solids
• PCBs
Special Precautions and Limitations
Shock Loadings--Impoundments are very sensitive to shock
loadings of toxic chemicals; leachate may need equalization
or pretreatment in some cases.
Temperature Effects:--Impoundments are most efficient dur-
ing warm weather (about 30 degrees C); cold weather or ice
formation will significantly reduce efficiency and require
longer detention times.
Suspended Solids--To reduce excess sludge removal require-
ments, the influent concentration of suspended solids
should be kept below about 0.1 percent for stabilization
ponds and 1.0 percent for aerated impoundments.
Gas Generation and Chemical Volatilization—Anaerobic
activity will generate methane and hydrogen sulfide. Vola-
tile chemicals will easily be transferred to the air.
Offensive odors and/or unacceptable human exposures may
result. An estimate of such volatilization losses may be
required.
Sludge Removal--Provisions must be made for the periodic
removal and disposal of excess sludge.
4.2.2.4 Design Basis (from Fair, et al., 1968; Adams
and Eckenfelder, 1974; and Hammer, 1975) .
The primary design parameters to be set are:
1, The type, number .and- configuration of impoundments to be
used.
237
-------
2. The detention time (which is related to influent and
effluent pollutant concentrations, degree of removal, tem-
perature and the nature of the wastes) .
3. The depth (and surface area) of the impoundment.
4. The sludge generation rate.
Secondary design parameters may be associated with the need for
mechanical aeration pretreatment (for removal of toxics and sus-
pended solids or equalization), and a final clarification step.
Type, number, configuration, and design of these parameters
will generally be determined from considerations of: (a) the nature
(including strength, composition) of the wastes; (b) the volume flow
rate to be treated (including likely variations in this flow); (c)
the land area available; (d) effluent limitations and the implied
removal efficiencies; (e) the local meteorology (temperatures,
insolation, rainfall}; and (f) costs. A design for a surface
impoundment should explicitly state how these factors were consid-
ered in the selection of the proposed design.
Design details should cover construction details, such as
impoundment bed, use of liners, dike slopes, freeboard, inlet and
outlet structures, connections between impoundments, access for
(and means of) sludge removal, and overflow protection.
Detention time (see Table 4-6) provides a summary of the range
of detention times (and other design parameters) associated with
various types of surface impoundments. For removal of BOD, COD,
TOG, the detention time may be derived from:
Cs -s \
V
where :
t = detention time (days)
= influent total BOD, C
= effluent soluble BOD, COD or TOC (mg/1)
SQ = influent total BOD, COD, TOC (mg/1)
238
-------
X = average or equilibrium concentration of VSS
in impoundment (mg/1)
k = specific organic removal rate coefficient
(1/mg-day)
Other equations for t are available (e.g., Fair et al., 1968)
which may be more appropriate in some cases than the one provided
above. A proposed design should clearly indicate how the detention
time was estimated and justify all assumptions and key inputs (e.g.,
X , k) used in the calculations.
In some cases it may be desirable to estimate the oxygen
requirements, the food-to-microorganism ratio, nutrient require-
ments; and, if mechanical aeration is used, the energy requirements.
Equations for these parameters are given in the discussion on Acti-
vated Sludge.
The depth of water in the impoundment will be determined prima-
rily by the type of impoundment selected. (See Table 4-6.) Land
availability and meteorology may be secondary factors.
.The required surface area (SA) of the impoundment may then be
roughly estimated from:
t™2\ - Flow (m3/d)• Detention time (t)
V III ) — — .
Depth (m)
A larger land area will be required than the area obtained from
the equation above since the equation assumed vertical walls and did
not consider the area required for the surrounding dike and access
areas.
It is necessary to estimate a sludge generation rate in order to
properly design any clarifier that may be used, e.g. , with an aerat-
ed impoundment, or to plan for periodic removal of excess sludge
from other impoundments where the sludge settles in situ. An
equation for estimating excess sludge production is provided in the
discussion on Activated Sludge.
239
-------
TABLE 4-6
TYPICAL VALUES OF DESIGN PARAMETERS FOR SURFACE IMPOUNDMENTS
NJ
-P-
o
Facultative Anaerobic Aerobic Aerated
Depth (m) 0.6 - 1.5 2.4 - 6.1 0.3 - 0.6 1.8 - 6.1
Organic Load
(kg BOD/km2/d) 1,100 - 11,000 25,000 - 225,000 10,000 - 22,000 1,100 - 33,000
Detention Time 7-30 30-50 2-6 3-10
(days)
Influent BOD 200 - 500 500 and up 200 200 - 500
Concentration
(mg/1)
Source: , ADL, 1976
-------
4.2.2.5 Principal Data Requirements
Kinetic Parameters (treatability studies). Same as for
activated sludge (viz), except biodegradable sludge frac-
tion not required.
Other Data—generally same as for activated sludge.
Non-biodegradable fraction and average MLVSS not required.
Summer and winter ambient conditions (minimum detention
time)
• temperature
• wind velocity
• insolation - solar radiation
• relative humidity
4.2.2.6 Elements of Cost Reviews,
Components
Construction and Capital--
• excavation
• construction materials
• pumps
• mixers
0 & M--
• electricity
• chemicals
241
-------
Major Factors
• excavation requirements
• process size
• impoundment lining material
Data
A cost example (unit and total costs) is given for an aerated
impoundment Table 4-7. Costs for an anerobic lagoon will be higher
than an aerated lagoon if the process is operated at elevated tem-
peratures. A cost example for an anerobic digestor is given in Table
4-8.
4.2.3 Rotating Biological Discs
4.2.3.1 Description
A rotating biological disc (RED) is a fixed film biological
method of treating effluent containing organic waste, similar in
operating principle to trickling filters. A series of discs (2-3
meter diameter), or drums in some configurations, coated with a
microbial film, rotate at 0.5-15 rev/min through troughs containing
the effluent. 40-50 percent of the disc surface area is immersed in
the effluent; the uncovered portion of the disc exposes the microbi-
al film to the atmosphere during each rotation out of the trough.
The shearing motion of the disc through the effluent keeps the
biological floe from becoming too dense. The discs are usually
arranged in series in groups of four. The process can be used for
roughing, secondary treatment and nitrification. A schematic of a
RED is shown in Figure 4-3 (EPA, 1982) .
4.2.3.2 Status
Conventional, undemonstrated (for leachate).
4.2.3.3 Feasibility and Effectiveness
242
-------
TABLE 4-7
COST ESTIMATES FOR AERATED SURFACE IMPOUNDMENTS
Basis: - 1 x 106 GPD; 10,000 ppm COD; 4,000 ppm BOD; 90% Removal-
30,034 Ib/day BOD; 365 day/yr operation
Estimated Capital Investment: $1,828,500
Variable Costs
Operating Labor
Maintenance (4% of Inv.)
Quicklime
Electricity
Ammonia
Phosphoric Acid
Total Variable Costs
Annual Cost Per Unit Annual Cost,
Quantity Quantity. 1982 $ 1982 $
8,760 MH
19.60/hour
400 tons 31.00/ton
5.35 x 106kWh .04/kWh
330 tons 210.00/ton
180 tons 520.00/ton
171,700
73,100
12,000
214,000
69,000
94,000
633,800
Taxes and Insurance (2% of Inv.)
Capital Recovery (10% - 10 years)
Total Fixed Costs
Total Annual Costs
Unit Cost ($/103 Gal)
36,600
297.300
333,900
967,700
2.65
Source: ADL, 1976
243
-------
TABLE 4-8
OPERATING COST ESTIMATES FOR ANAEROBIC DIGESTION SYSTEM
Basis: - 100,000 GPD; 5% solids - 365 days/yer; 0.5 Ibs volatile
solids per cubic foot of digestor capacity per day.
Estimated Capital Investment: $2,025,000
Annual Cost Per Unit Annual Cost,
Quantity Quantity, 1982 $ 1982 $
Variable Cost
Operating Labor 8,760 MH 19.60/hour 1?>1,700
Maintenance (4% of Inv.) 81,000
Quicklime 200 tons 31.00 6,000
Electricity 450 x 103kWh .04/kWh 18,000
Total Variable Costs 276,700
Fixed Costs
Taxes and Insurance (2% of Inv.) 40,500
Capital Recovery (10%-10 yrs.) 314,300
Total Fixed Costs 354,800
Total Costs 631,500
Unit Cost ($/103 gal) 17.30
Source: ADL, 1976
244
-------
FIGURE 4-3
ROTATING BIOLOGICAL DISC TREATMENT SCHEMATIC
(Source: ADL, 1976)
Bio-Surf Units
Primary Treatment
Secondary Clarifier
General Features
As indicated in the schematic, RED typically requires both pri-
mary treatment and secondary clarification. A large treatment sys-
tem may combine several modular RED units in a number of parallel
trains with each train containing units in series.
A RED process should be capable of treating the same type of
wastes as- an activated sludge or aerated impoundment process. BOD
removal efficiencies should also be comparable. Key features of
RBDs which may differentiate them are the characteristic modular
construction, ease of operation, good settleability of solids
flushed from the disc surfaces, low hydraulic head loss, and shallow
excavation which make it adaptable to new or existing treatment
facilities. In addition, enclosed (covered) systems may be used to
provide some protection against low temperatures (EPA, 1980;
Hammer, 1975).
RBDs are considered to be more reliable than other fixed bed
processes because they withstand hydraulic and organic surges more
245
-------
effectively. Also, they do not plug up in the manner that trickling
filters may (Metcalf and Eddy, 1979) .
Special Precautions and Limitations
Like other biological treatment units, RBDs are sensitive to
temperature changes and removal efficiencies will fall with temper-
atures below 20 degrees C. Enclosed units will provide some pro-
tection, but condensation (and freezing of the condensate) maybe a
problem in very cold periods. High organic loadings may result in
septic conditions in the first stage, and supplemental aeration may
be required. Use of dense media for early stages may result in media
clogging (EPA, 1980). In addition, as with activated sludge organ-
isms, the biological media are sensitive to pH and some toxic metals
and organisms which may be present in leachate from hazardous waste
disposal sites.
4.2.3.4 Design Basis
The primary design parameters to be set are:
• the number and configuration of RBDs to be used;
• the detention time of the wastes in the chambers;
• the rotational velocity of the media; and
• the sludge generation rate.
Secondary design parameters may be associated with the pre- and
post-treatment units, the possible need for supplemental aeration
in the first stages, the possible need for nutrient addition and
covers, and the specific design of the discs to be used.
Table 4-9 provides a summary of typical values or ranges for
several design parameters that are applicable to industrial or
municipal wastewater treatment.
Number and Configuration
The comments provided in the discussion on Surface Impoundments
are applicable here and are not repeated.
246
-------
TABLE 4-9
DESIGN CRITERIA FOR ROTATING BIOLOGICAL DISKS
Criteria
Units
Range/value
Organic loading
Hydraulic loading
Stages/train
Parallel trains
Rotational velocity
Media surface area
Media submerged
Tank volume
Detention time
Secondary
Clarifier overflow
Power
Ib BOD. 1,000 ft of media Without nitrification: 30-60
With nitrification: 15-20
gpd/ft of media
ft/rain (peripheral)
ft2/ft3
percent
gal/ft of disc area
Without nitrification: 0.75-1.5
With nitrification: 0.3-0.6
At least 4
At lease 2
60
Disc type: 20-25
Lattic type: 30-35
40
0.12
min (based on 0.12 gal/ft ) Without nitrification: 40-9-
With nitrification: 90-230
gpd/ft 500-700
hourse-power/25 ft shaft 7.5
Source: EPA, 1980
Detention Time
Typical detention times for RBDs used in municipal or indus-
trial systems are 40-90 minutes without nitrification and 90-230
minutes with nitrification (EPA, 1980). These ranges may be appli-
cable for leachates containing easily degradable compounds.
No simple equations are available from which a design detention
time may be calculated. (The equations given previously for acti-
vated sludge and aerated impoundments might be used if the parame-
ters x, and k can be determined.) The detention time will be a
function of several variables including: (a) the nature of the
wastes, influent concentrations, and desired removal efficiencies;
(b) the rate of biodegradation (a function of temperature); (c) the
number of discs used (expressed as disc surface area/tank volume);
(d) the rotational velocity of the discs (which affects reaeration
rates and the stripping of solids from the discs) .
247
-------
Rotational Velocity of Media
As indicated in Table 4-9, the rotational (peripheral) velocity
may typically be set at about 18 m/min (60 ft/min). A higher rota-
tional velocity may enhance biodegradation if oxygen supply is rate
limiting. Lower velocities may allow the build-up of more floe on
the discs and require less power. Since the rotational velocity can
be changed (after installation of the RED units), it is only impor-
tant that the design provide an approximate value.
Sludge Generation Rate
It is necessary to estimate a sludge generation rate in order to
properly design the post-treatment clarifier. An equation for esti-
mating excess sludge production is provided in the discussion on
Activated Sludge.
In municipal systems, sludge is generated at a rate of about
3000-4000 i per 106 l of wastewater(60-84 kg of dry solids per 106
1).
4.2.3.5 Principal Data Requirements
Generally similar to surface impoundment requirements.
4.2.3.6 Elements of Cost Review
Components
Construction and Capital--
• construction
• tanks
• biological disc
• pumps
248
-------
0 & M—
• electricity
• chemicals
Major Factors
Process size
Data
Construction and O & M costs as a function wastewater treated
are shown in Figures 4-4 and 4-5.
4.2.4 Trickling Filters
4.2.4.1 Description
Trickling filters are a form of biological treatment in which a
liquid waste of less than 1 percent suspended solids is trickled
over a bed of rocks or synthetic media upon which a slime of microbi-
al organisms is grown. The microbes decompose organic matter aero-
bically; these conditions are maintained at the outer slime surface
by updrafts of air. Some anaerobic decomposition may occur at the
interior surface adjacent to the trickling bed media. Periodically,
the slime layer sloughs off due to the weight of the microbial growth
or the hydraulic flow rate of the effluent. A schematic diagram of a
typical trickling filter treatment system appears in Figure 4-6.
4.2.4.2 Status
Conventional; undemonstrated.
4.2.4.3 Feasibility and Effectiveness
249
-------
FIGURE 4-4
FIGURE 4-5
CONSTRUCTION COSTS FOR ROTATING
BIOLOGICAL DISCSa
(Source: EPA, 1982)
100
10
1.
o
i
5
I,
01
f
s
/
£
/
y
; CONSTRUCTION
•
f
t
f
/i
/
'
0«pd/
COST-
'-',''•
f 2
01 10 10
Wastewater Flow, Mgal/d
10
°_ 01
M
II
1!
0001
01
O&M COSTS FOR ROTATING
BIOLOGICAL DISCSa
(Source: EPA, 1982)
x
/
-<
**~
/
OPERATION a MAINTENANCE
^
/
, •
7
. , ^"
,--
1
^
•
f
J
Y
yf
/
K
— Ji
'
'
/ *
COST
Total
^ Pe*
•'
•; Labor
-Ma
•r
all
. 00001
10 10
Wastewater Flow, Mgal/d
100
ato adjust costs to 1982 dollars, multiply by 1.62.
ato adjust to 1982 dollars, multiply by:
labor - 1.64
power — 2.0
materials — 1.52.
Basis
1,
ft^/shaft),-motor drives (5 hp/shaft), molded fiberglass covers,
and reinforced concrete basins.
Construction cost includes RBD shafts (standard media, 100,000
2
2. Cost does not include final clarifiers.
3. Loading rate - 1.0 gal/d/ft .
250
-------
FIGURE 4-6
TRICKLING FILTER TREATMENT SYSTEM SCHEMATIC
(Source: EPA, 1980)
PUMP STATION
to
RAW WASTEWATER
RECIRCULATION
i
*u
_J p
l_ —
HIGH RATE,
ROCK MEDIA
TRICKLING
FILTER _
1
FINAL
CLARIFIER
i
1
/VASTE SLUDGE
i *
1
EFFLUENT
RAW SLUDGE
RECIRCULATION
-------
General Features
Trickling filters reduce BOD by 10-20 percent when used for pri-
mary treatment (roughing) and 50-90 percent when used for secondary
waste treatment ("low rate") (EPA, 1982). Most current usage of
trickling filters is considered "high rate;" for these, BOD removal
efficiencies appear to range from 76-98 percent (EPA, 1980).
As shown in the figure above, recirculation of some wastewater
is usually required to improve removal efficiencies and/or to even
out flows and help operate self-propelled distributors. Recircu-
lation may involve underflow from the trickling filter and/or over-
or under-flow from the final clarifier.
A trickling filter should be capable of treating the same type
of wastes as activated sludge or aerated impoundment processes. For
situations involving a high-strength influent and/or a low effluent
limitation (e.g., 30 mg/1 BOD), it may be necessary to operate two
trickling filters in series. For municipal and industrial wastewa-
ters (which contain significant amounts of suspended solids in the
raw waste), a primary clarifier is essential. Except for covered
systems, the oxygen requirements can be met by natural aeration of
the filter bed.
The wastewater distribution system for the filter beds may con-
sist of stationary nozzle fields or rotating manifolds (driven by
motor or self propelled from the hydraulic head) . The system
selected will depend on the diameter of the filter units, the flow
volume and variability, and other factors. The design submitted
should indicate why it is appropriate for the proposed system.
Special Precautions and Limitations
Trickling filters are considered fairly reliable as long as
variations in the operating conditions (flow rates, composition)
are minimized and the temperature of the wastewater remains above
about 13 degrees C. Odors and flies may be a problem (EPA, 1980).
Inadequate hydraulic flow rates may prevent the normal sloughing of
the biological slime off the filter media; this can lead to clogging
and surface ponding.
Some temperature protection is afforded by the use of covers
over the filter beds. In this case, however, forced ventilation is
252
-------
required to maintain an air velocity of about 1 ft/min in the filter
bed (Fair et al. , 1968) .
4.2.4.4 Design Basis
The primary design parameters to be set are:
• The type, number, size, and configuration of filter units
to be used, including provisions for recycle and pre- and
post-treatment.
• The pollutant load factor (expressed as Ib BODs/ft3 day or
Ib BODs/acre ft day).
• The hydraulic load (Mgal /acre day or gal/ft2 day) .
• The recirculation ratio.
• The sludge generation rate.
Secondary design parameters may be associated with the initial
and final clarifiers, the possible need for nutrient addition and
covers, the bed depth, media type, air requirements (for covered
systems) and other factors.
Table 4-10 provides a summary of typical values or ranges for
several design criteria of trickling filters that are applicable to
municipal and industrial wastewaters.
Type, Number, Size and Configuration — these will be deter-
mined by a number of factors. The general comments provided under
the discussion of Surface Impoundments are applicable here and are
not repeated. The size of the unit(s) is derived from consider-
ations of the pollutant and hydraulic loads.
Pollutant loads — pollutant loads typically used in industrial
and municipal trickling filters are shown in Table 4-10. For high
rate filters (rock or plastic media) the loads for secondary treat-
ment are in the range of 10-60 Ibs BOD5/1000 ft3 day. The BOD load
may be calculated from the raw BOD in the primary effluent, without
regard to any BOD contribution in the recirculation flow (Hammer,
1975):
253
-------
TABLE 4-10
DESIGN CRITERIA FOR TRICKLING FILTERS
Criteria/Factor
Unit
Value/Range
High Rate/Rock Media
Hydraulic loading
(with recirculation)
Organic loading
Recirculation ration
Bed depth
Under drain minimum slope
Power requirements
Dosing interval
Sloughing
Media - rock
Mgal/acre/d/or
gal/d/ft2
Ib BOD5/d/acre ft or
Ib BOD5/d/l,000 ft3
ft
hp/Mgal
sec
in
10 - 40
230 - 900
900 - 2,600
20 - 60
0.5 - 4
3-6
1
10 - 50
< 15 (continuous)
Continuous
1-5
Low Rate/Rock Media
Hydraulic loading
Organic loading
Recirculation ratio
Bed depth
Under drain minimum slope
Effluent channel minimum
velocity (at average
daily flow)
Media - rock
Mgal/acre/d or
gal/d/ft2
Ib BOD5/d/acre ft or
Ib BOD5/d/l,000 ft3
ft
ft/sec
in
1-4
25 - 90
200 - 900
5-20
0
5-10
1
2
1-5
Sloughing
Dosing interval
Intermittent
Continuous for majority of
daily operating schedule,
but become intermittent
during low flow periods
(Cont.)
254
-------
TABLE 4-10
DESIGN CRITERIA FOR TRICKLING FILTERS (Cont.)
Plastic Media
Hydraulic loading
(with recirculation)
a) Secondary treatment
b) Roughing
Organic loading
a) Secondary treatment
b) Roughing
Recirculation ratio
Dosing interval
(continuous)
Sloughing
Bed depth
Power requirement
Under drain minimum slope
Mgal/4cre/d or
gal/4/ft2
Mgal/4cre/d or
gal/cj/ft2
*
Ib BOD5/d/acre ft
Ib BCJDr/d/1,000
Ib BOD5/d/acre ft
Ib BQD5/d/l,000
sec
ft
hp/Mg4l
30 - 60
700 - 1,400
100 - 200
2,300 - 4,600
or 450 - 2,200
t3 10 - 50
or 4,500 - 22,000
t3 100 - 500
0.5 - 5
£15
Continuous
20 - 30
10 - 50
1
Source: EPA, 1980
BOD load (lb/1000 ft -day)
Q(8.34)BOD of primary effluent
10~3-Volume of Filter media (ft3)
where Q is the raw wastewater flow (Mgal/d) .
Hydraulic load -- hydraulic loads for high rate filters (with
recirculation, plastic or rock media) range from 230-1400 gal/ft2
day (Table 4-10). Given a rawjwaste flow of Q (Mgal/d), a recircu-
lation flow of Qr (Mgal/d), and a filter surface area of A (ft2), the
hydraulic load is (Hammer, 1975):
Hydraulic load (Mgal/ft2-d) =
Q + Q
R
255
-------
Recirculation Ratio -- the recirculation ratio (R) is defined
as:
Recirculation flow rate
~ Raw waste flow rate
For high rate filters, R is in the range of 0.5-5 (see Table
4-10). The degree of recirculation required may depend -on several
factors including the need to provide more even flow rates, to
increase flows to enhance floe removal, to increase removal effi-
ciencies, and/or to provide sufficient flow to operate
self-propelled diffusers.
Size -- Figure 4-7 provides guidance on the optimum dimensions
(for larger systems) given information on the influent and (desired)
effluent BOD levels, the raw waste flow, and the recirculation
ratio.
Sludge generation rate -- it is necessary to estimate a sludge
generation rate in order to properly design the post-treatment clar-
ifier. An equation for estimating excess sludge production is pro-
vided in the section on Activated Sludge. According to the EPA
Treatability Manual (EPA, 1980) the following sludge generation
rates are typical for municipal wastewaters:
Sludge Generation
Ibs dry
gal/Mgal solids/Mgal
High rate/rock media 2500 - 3000 400 - 500
High rate/plastic media 3000 - 4000 500 - 700
4.2.4.5 Principal Data Requirements
Generally similar to surface impoundment requirements.
4.2.4.6 Elements of Cost Review
256
-------
FIGURE 4-7
OPTIMAL DIMENSIONS OF TRICKLING FILTERS
(Operated at 18°C (64°F) and Maximum Recirculation Ratios.
Hydraulic Load 30 MGAD, Maximum Depth 10 Ft.)
(Source: Fair,.et al., 1968)
Used by permission, see Copyright Notice
200
Filter diameter, ft
40 80 120 160 200
tu
468
Filter depth, ft
10 1 234567
Recirculation, mgd
Components
Construction and Capital--
tanks
pumps
clarifier
0 & M--
chemicals
electricity
257
-------
Major Factors
Process capacity
Data
A cost example (unit and total costs) is presented in Table
4-11.
4.2.5 Land Treatment
4.2.5.1 Description
Land treatment is "the intimate mixing or dispersion of wastes
into the upper zone of the soil-plant system with the objective of
microbial stabilization, adsorption and immobilization leading to
an environmentally acceptable assimilation of waste." (Overcash and
Pal, 1979. ) Land treatment differs from other land-based approaches
to waste management in that the ratio of waste t6 soil is very low
over the impacted area.
4.2.5.2 Status
Irrigation: Conventional, undemonstrated; most widely
used type of land application for treatment of municipal
wastewaters. Industrial waters (i.e., paper and pulp,
dairy) have also been treated in this manner. Not known if
process has been applied to leachates.
Overland flow: Developmental; overland flow has been
developed for use in the U.S. for food processing wastewa-
ter effluent. Not known if the system has been applied to
leachate treatment.
Infiltration-Percolation: Conventional, undemonstrated.
Has been used for pretreated municipal wastewater. Infor-
mation not available for leachate.
Leachate recycle: Developmental; relatively recent devel-
opment and is not widely practiced.
258
-------
TABLE 4-1]
COST ESTIMATES FOR TRICKLING FILTERS
Basis: 1 x 10 GPD, 10,000 ppm COD, 4,000 ppm BOD, 365 day/yr operation
Estimated Capital Investment: 3,726,000
Annual
Quantity
Cost Per Unit
Quantity, 1982 $
Annual Cost,
1982 $
Variable Costs
Operating Labor 8,760 MH
Maintenance (2% of Inv.)
Quicklime 400 tons
Electricity 1.1 x 106 kWh
Ammonia 330 tons
Phosphoric Acid 180 tons
Total Variable Costs
Fixed Costs
Taxes and Insurance (2% of Inv.)
Capital Recovery (10% - 10 years)
Total Fixed Costs
Total Costs
Unit Cost ($/1000 Gal)
19.60/hour
31.00/ton
.04/kWh
210.00/ton
520.00/ton
171,700
74»500
12,000
44,000
69,000
94,000
465,200
74,500
601,000
675,500
1,140,700
3.13
Source: ADL, 1976
259
-------
4.2.5.3 Feasibility and Effectiveness
General Features
There are four major land treatment configurations:
• Irrigation (Figure 4-8): Leachate is sprayed (spray irri-
gation), flooded (flood irrigation), or applied by gravity
flow (ridge and furrow irrigation) to sustain the growth of
plants.
• Overland flow (Figure 4-8): Also known as "grass filtra-
tion," leachate is sprayed onto a gently-sloping, relative-
ly impervious soil planted with vegetation. Biological
treatment occurs as the wastewater contacts biota in the
ground cover vegetation.
• Infiltration-Percolation (Figure 4-8): Large volumes of
leachate are applied to the land, infiltrate the surface
and percolate through the soil pores.
• Leachate recycle (Figure 4-9): Leachate is pumped out of
the contaminated area and recycled through the plot.
Most leachates containing biodegradable pollutants can be at
least partially treated by land application. Non-degradable,
adsorbable species, including some heavy metals, will be retained in
the soil. The degree to which specific waste cations will be
adsorbed depends on the soil, waste loading, and competing cations.
Most anions will not be retained in the soils.
Typical removal efficiencies for conventional pollutants are
shown in Table 4-12.
Biological seeding may be used to augment the activity of the
indigenous soil bacteria or to offset loss of activity following a
serious upset.
Performing rigorous calculations on assimilative capacity will
minimize (but not eliminate) concerns with regard to the long-term
adverse effects on the soil-plant-groundwater system.
Additionally, some form of post-treatment closure care may be
required.
260
-------
SPRAY OR
SURFACE
APPLICATION
ROOT ZONE
SUBSOIL
SPRAY APPLICATION
SLOPE 2-4%
FIGURE 4-8
LAND APPLICATION APPROACHES
(Source: Pound and Crites, 1973)
EVAPORATION
SLOPE
VARIABLE
-DEEP
PERCOLATION
(a) IRRIGATION
EVAPORATION
GRASS AND VEGETATIVE LITTER
SHEET FLOW
,—RUNOFF
L, COLLECTION
(b) OVERLAND FLOW
.EVAPORATION SpRAY QR
\ , SURFACE APPLICATION
INFILTRATION-
ZONE OF AERATION
AND TREATMENT
RECHARG£ MOUND-
-PERCOLATION THROUGH
UNSATURATED ZONE
-NEW WATER TABLE
OLD WATER TABLE-
CO INFILTRATION-PERCOLATION
261
-------
FIGURE 4-9
SCHEMATIC OF A LEACHATE RECYCLE SYSTEM
(Source: ADL, 1976)
- - [-1
Other concerns are:
• Salt build-up in the topsoil due to excessive water evapo-
ration.
• Aerosol drift (fine sprays reduce the runoff potential but
increase drift and associated downwind air pollution) .
• Odors (volatile chemicals in leachate may easily volatilize
during spray application).
• Uneven distribution of leachate over land area and/or
uneven percolation rates.
• Erosion.
262
-------
TABLE 4-12
REMOVAL EFFICIENCY FOR LAND TREATMENT OPTIONS
Parameter
COD
BOD
SS
N
P
Leachate
Recycle3 Irrigation0
97
98 90-99
90-99
<90
80-99
Overland Flowb
90-99
90-99
70-90
50-60
Infiltration-
Percolation a
90-99
90-99
0-80
70-95
^anaerobic treatment after 15 days dentention time, Pohland;1975,
Pound and Crites, 1973
• Clogging of pipes and nozzles. It may be necessary to
screen or filter solids from the wastes.
• Selection of crop cover, frequency of harvesting, and use
of harvested crop (if any).
• Build up of other undesirable contaminants, if present.
4.2.5.4 Design Basis
In spite of its apparent simplicity, there are several compo-
nents to a land treatment system for leachate. In addition to leach-
ate collection, typical components are (overcash and Pal, 1979) :
• Transmission or conveyance
• Storage
• Application system (design, spacing)
• Land purchase and preparation for vegetative cover
• Buffer zone
• Monitoring
263
-------
• Operational control systems
• Diversions and land management practices
• Agricultural equipment for vegetative cover
• Operation and management manual
While it is important for a design to be complete in its cover-
age of all such items, the primary design constraint is the assimi-
lative capacity of the soil-plant-groundwater system being used.
The constraint is expressed by Overcash and Pal (1979) as follows:
The waste, when considered on a constituent by constituent
basis, shall be applied to the plant-soil system at such rates or
over such limited time spans that no land is irreversibly removed
from some other societal usage.
They further recommend that assimilative capacity be determined
for three broad types of pollutants:
• Those that degrade or require plant uptake for assimilation
in the plant-soil system, e.g., oils or organics;
• Those that are relatively immobile and nondegradative, thus
are permitted to accumulate in soils to predetermined crit-
ical levels, e.g., heavy metals; and
• Those that are mobile and nondegradable and must be assim-
ilated over land areas so that receiving waters are not
altered to a degree requiring further drinking water treat-
ment, e.g., anionic species.
The calculation of assimilative capacity for each pollutant of
concern must consider not only the nature of that pollutant (biode-
gradability, mobility, uptake, toxicity); but also the site envi-
ronmental factors (soil type, meteorology, hydrogeology). Maximum
site life is dependent on the accumulation rate and acceptable soil
levels of immobile, nondegradable contaminants such as heavy
metals. A significant amount of laboratory and/or field data may be
required. (Additional details on such calcualtions are provided by
Overcash and Pal, 1979. )
In each case the assimilative capacity calculated (e.g., in
kg/ha/yr) and compared with the waste generation rate (kg/yr)
264
-------
derived from data on leachate composition and collection rates. The
ratio of these two numbers is the land area (ha) required to assim-
ilate each constitutent. The constituent with the largest land area
requirement is referred to as the land-limiting constituent (LLC).
If all of the pollutants are easily assimilated, it is possible that
water could be the LLC as a result of the soil permeability and other
factors.
The assimilative capacity for the land-limiting
constituents(s) should be estimated for different seasons. This can
then be translated into a leachate assimilative capacity expressed
in terms of leachate depth applied per unit time (e.g., cm/mo). The
following equations can be used:
Leachate Assimilative Capacity (cm/mo)=
A. 100
(1)
F-C
R-100
(2)
X-1200
(3)
where:
F = Leachate flow rate (m3/mo)
A = Area of land application (ha) = R/C
C = Assimilative capacity of system for LLC (kg/ha-yr)
R = Rate of waste generation/application (kg/yr) =
12-F-X
X = Concentration of LLC in leachate (kg/m3)
Leachate storage requirements can be estimated by comparing
such monthly assimilative capacities with leachate volumes being
generated. Note that storage requirements can be minimized by using
a land application area derived from a worst-case application of
equations 1, 2, or 3. In many cases, this will be the winter months
when biological activity and permeabilities are reduced. The maxi-
mum storage requirement in northern climates may be as much as 160
days; in the northwest and southeast portions of the U.S., storage
may be required during prolonged wet spells (Overcash and Pal,
1979). Table 4-13 lists ranges of typical design parameters for
these land treatment techniques used for municipal wastes. These
design parameter values may differ significantly from those needed
to accommodate land treatment of leachate.
265
-------
TABLE 4-13
COMPARATIVE CHARACTERISTICS OF
LAND APPLICATION APPROACHES
Feature
Application techniques
Annual loading
rate, m
Field area
required, ha
Typical weekly
loading rate, cm
Disposition of
applied wastewater
Slow rate
Sprinkler
or surface3
0.5-6
23-280
1.3-10
Evapotranspiration
and percolation
Rapid Infiltration
Usually surface
6-125
3-23
10-240
Mainly
percolation
Overland flow
Sprinkler or
surface
3-20
6.5-44
6-40c
Surface runoff and
evapotranspiration
Need for negotiation
Required
Optional
with some
percolation
Required
Grade
Soil permeability
Depth to ground
water
Climatic restrictions
Less than 20% on
cultivated land;
less than 40% on
noncultivated land
Moderately slow to
moderately rapid
0.6-1 m (minimum)6
Storage often
needed for cold
weather and during
heavy precipitation
Not critical; excessive
grades require much
earthwork
Rapid (sands, sandy loams)
1 m during flood cycle ;
1.5—3 m during drying cycle
None (possibly modify
operation in cold weather)
Finish slopes 2-8
Slow (clays, silts,
and soils with
impermeable barriers)
Not criticalf
Storage usually needed
for cold weather
a. Includes ridge-and-furrow and border strip.
b. Field area in hectares not including buffer area, roads, or ditches.
c. Range includes raw wastewater to secondary effluent, higher rates for higher level of
preapplication treatment.
d. Steeper grades might be feasible at reduced hydraulic loadings.
e. Underdrains can be used to maintain this level at sites with high ground water table.
f. Impact on ground water should be considered for more permeable soils.
Source: EPA, 1981
266
-------
Additional information on design of land treatment facilities
can be found in TRD 8.
4.2.5.5 Principal Data Requirements
Assimilative capacity of the soil-plant-groundwater
system. (Details for specific pollutants may require data
on biodegradability, uptake, mobility and toxicity can be
found in Table 4-14.) Calculations should identify the
land-limiting contaminant (LLC) and the acceptable sea-
sonal assimilative capacity rates.
Leachate composition and flow (including variability in
time)
Characteristics of the soil in area to be used (type, organ-
ic carbon content, cation exchange capacity, permeability,
etc. )
Meteorology (temperatures, precipitation, solar
insolation)
Local hydrogeology (groundwater depth and flows, runoff
potential, water uses)
Various aspects of the last three items are presented in Table
4-15 which lists site selection factors and criteria for municipal
waste waters. Selection criteria for land treatment of leachate
from hazardous waste sites may differ.
4.2.5.6 Elements of Cost Review
Components
Construction and Capital--
• application equipment
• monitoring instrumentation
O & M--
267
-------
TABLE 4-14
ESSENTIAL CONSIDERATIONS IN A COMPREHENSIVE TESTING PROGRAM
FOR APPRAISING WASTE-SITE INTERACTIONS
Waste Site
Interactions
Test Method
Manual
Reference
Degradation of
waste
Accumulation in
soil of
nondegradables
Leaching hazards
Run-off hazards
Volatilization
hazards
Acute toxicity
Chronic toxicity
Plant uptake
(optional)
Pretreatment
Respirometry 7.2.1
Field studies by soil
testing 7.5.3.1.4
Waste analysis
(inorganics) 6.4
Respirometry (organics) 7.2.1
Soil thin layer
chromatography 7.2.2.1
Soil leaching columns 7.2.2.2
Field soil leachate
testing 7.5.3.1.2
Rainfall simulation 7.2.2.3
Environmental chamber 7.2.3
Field air testing 7.5.3.1.1
Respirometry (soil
biota) 7.2.1
Greenhouse pot
studies (plants) 7.3
Microbiological muta-
genicity assays 7.2.4
Greenhouse pot studies 7.3
Assessment of processes
generating waste 6.3
Source: TRD 8
268
-------
TABLE 4-15
SITE SELECTION FACTORS AND CRITERIA FOR EFFLUENT IRRIGATION2
Factor
Criterion
Soil
Soil drainability
Soil depth
Depth to groundwater
Groundwater control
Groundwater movement
Slopes
Underground formations
Isolation
Distance from source
of wastewater
Loamy soils preferable but most
soils from sands to clays are
acceptable.
Well drained soil is preferable;
consult experienced agricultural
advisors.
Uniformly 5 to 6 ft or more
throughout sites is preferred.
Minimum of 5 ft is preferred.
Drainage to obtain this minimum
may be required.
May be necessary to ensure
renovation if water table is less
than 10 ft from surface.
Velociity and direction must be
determined.
Up to 15 percent are acceptable
with or without terracing.
Should be mapped and anlyzed
with respect to interference
with groundwater or percolating
water movement.
Moderate isolation from public
preferable, degree dependent on
wastewater characteristics,
method of application, and crop.
A matter of economics
Based on municipal wastewater.
Source: Pound and Crites, 1973
269
-------
• pH control
Major Factors
• Site preparation requirements
Data
Costs are very sensitive to site and waste specific factors. For
detailed cost information and cost estimating techniques for land
treatment systems, see Reed, 1979.
4.3 CHEMICAL TREATMENT
4.3.1 Neutralization
4.3.1.1 Description
Neutralization, used by itself, is a process used to adjust the
pH (acidity or alkalinity) of a waste stream to an acceptable level
for discharge, usually between 6.0 to 9.0 pH units. Neutralization
may also be used as a pre- or post-treatment step with other treat-
ment processes. Adjustment of pH is done by adding acidic reagents
or acidic wastes to alkaline streams and vice versa. Figure 4-10
shows a three-stage neutralization system schematic including:
• initial neutralization
• equalization
• final adjustment
There are other alternative configurations.
4.3.1.2 Status
Conventional, demonstrated.
270
-------
FIGURE 4-10
NEUTRALIZATION TREATMENT SYSTEM SCHEMATIC DIAGRAM
(Source: ADL, 1976)
N3
-J
Neutralizing Chemical
Feed System
Incoming Water
pH Meter Controller
pH Flow Cells
Sample Pumps.
ho
V
>c
!
=3
*
I
^
\
•=>
\
(
^
I
=>
Neutralized Wa
Neutralizing Chemical
Feed System
-------
4.3.1.3 Feasibility and Effectiveness
General Features
Neutralization is generally applicable to aqueous leachate
streams; some non-aqueous materials such as acid phenols and carbox-
yl acids can also be treated by neutralization.
The selection of reagent depends strongly on cost consider-
ations. The salient characteristics of the most common reagents
are:
Sulfuric Acid -- Commonly preferred acid reagent because of
its relatively lower cost. It does have the potential to
form insoluble salts which present equipment scaling and
solids handling problems.
Hydrochloric Acid -- Neutralization products are generally
soluble which eliminates the problems associated with sol-
ids formation. However, it is important to consider dis-
charge limitations on dissolved solids when using
hydrochloric acid.
Sodium Reagents (caustic soda, soda ash) -- Because sodium
reagents are very soluble in water relative to other basic
reagents, they can be handled as concentrated solutions
which reduce storage and equipment capacity requirements.
Raw material costs are higher than other basic reagents.
Calcium Reagents (lime, quicklime, limestone) — Calcium
reagents have low water solubilities and are generally fed
to a neutralization tank as slurries on the order of 15 per-
cent solids. This increases the capital cost asociated
with handling these reagents. If sulfate ions are present
in the leachate, insoluble calcium sulfate will be formed
posing potential scaling and solids handling problems.
Magnesium Reagents (dolomitic lime, dolomitic limestone)
— Magnesium reagents eliminate the scaling and solids for-
mation problems associated with calcium reagents and wash-
streams containing sulfate ions.
Waste acids or alkalies, if available, can be used to neutralize
leachate streams.
272
-------
Special Precauti-ons and Limitations
The reagents used in neutralization and the untreated waste may
be quite corrosive. It is important to select compatible con-
struction materials. Appropriate materials (at ambient temper-
atures) for each of the principal reagent classes are:
Sulfuric acid (75-95%) -- lead: (<10%) -- lead or rubber;
• Hydrochloric acid (dilute or concentrated) -- rubber;
• Sodium base (concentrated) — 316SS or rubber, (dilute) —
316SS, rubber, carbon steel, or cast iron;
• Calcium base — 316SS, rubber, or carbon steel.
4.3.1.4 Design Basis
Principal design parameters are:
• flow
• neutralization reagent addition rate
Reagent addition rate is determined by laboratory tests to pre-
pare a neutralization curve, showing the amount of reagent added to
a unit quantity of wastes versus resultant pH. Figure 4-11 shows a
typical curve.
Tank sizes are based on the flow and detention time which is
typically 5 to 10 minutes per stage (Adams and Eckenfelder, 1974).
The tank size capacity is calculated as follows:
T.S. = (#Stages)
273
-------
FIGURE 4-11
NEUTRALIZATION CURVE
(After: Adams & Eckenfelder, 1974)
14.0
10.0
PH
6.0
2.0
Second Stage
pH=7.0
First Stage
mg/l
added
where;
T.S. = tank size
flow = flow of influent
R.T. = reaction time
^Stages = number of neutralization stages
Mixing power levels are (Adams and Eckenfelder, 1974)
• for air systems — 1 to 3 scfm/ ft2 for a 9-foot liquid
depth; and
• for mechanical system -- .2 to .4 hp/1000 gal
274
-------
4.3.1.5 Principal Data Requirements
• expected leachate average daily and variability of flow
rate (system size)
• leachate acidity or alkalinity (mg/1 CaCO^) (reagent
requirements)
• pH titration curve, as shown in Figure 4-11 (reagent
requirements)
4.3.1.6 Elements of Cost Review
Components
Construction and Capital--
• tanks
• pumps
• mixers
• monitoring instrumentation
0 & M—
• chemicals
• electricity
Major Factors
• process volume
• neutralization chemical requirements
Data (Adams and Eckenfelder, 1974)
Capital and 0 & M costs in 1982 dollars, are $936,000 -
$1,170,500 and 1,000 per million gallons treated, respectively, for
275
-------
a neutralization system to treat:
• 500,000 gpd
• 20,000mg/l CaCOs equivalent
• 100 - 500 mg/1 suspended solids
4.3.2 Precipitation
4.3.2.1 Description
Precipitation is a widely used (in industrial practice), rela-
tively low-cost physical chemical technique in which the chemical
equilibrium of a waste is changed to reduce the solubility of the
undesired components. These components precipitate out of
solution, as a solid phase, often in the form of small or even col-
loidal particles, and are removed by one of several possible solids
removal techniques. Precipitation is most commonly used to treat
heavy metals-containing wastes.
4.3.2.2 Status
Conventional, demonstrated.
4.3.2.3 Feasibility and Effectiveness
General Features
Precipitation is induced by one of the following means:
• adding a chemical that will react with the hazardous con-
stituent in solution to form a sparingly soluble compound.
• adding a chemical to cause a shift in solubility equilib-
rium, reducing the solubility of the hazardous substance.
• changing the temperature of a saturated or nearly saturated
solutiorLjLn the direction of decreased solubility.
276
-------
Chemical additives are most commonly used. Typical reagents
are:
sodium hydroxide, sodium sulfide
lime (Ca(OH)2)
iron salts, iron sulfide, ferric sulfate
phosphate salts (especially for heavy metals
such as As, Cd, Cr, Zn, Cu, Pb, Hg, Ni)
alum (A12 (SOit) 3)
The theoretical removal limits for many metal species is very
low, particularly with sulfide precipitants. Figure 4-12 shows the-
oretical curves as a function of waste pH. Some organic species --
for example, aromatic compounds and phthalates -- can also be treat-
ed. Removal in practice often is one to two orders of magnitude less
than the theoretical limit. Complexing agents, such as cyanide or
EDTA, compete with the precipitant and may hold the species in sol-
ution.
Conventional precipitation processes are performed in the fol-
lowing three steps:
1. rapid mixing of precipitating chemicals and wastewater;
2. slow mixing of treated wastewater in a flocculation tank to
allow settleable floes to form; and
3. sedimentation of solids in a clarification tank.
The solids are removed by either:
• sedimentation, which separates the phases by the gravita-
tional settling of the precipitate to the bottom of the sed-
imentation tank;
• filtration, which separates the phases by passing the pre-
cipitation effluent through a granular or cloth barrier,
retaining the particles and allowing the clear effluent to
pass through, or
277
-------
Concentration of Dissolved Metal (mg/^)
o
q
o>
N>
O>
00
to
00
O
r~
c
DO
m
I C
o -< 30
i/j O m
§ 30 *.
1. O I
"(D >< N
rt O
9L m
-• v>
e«
c
o
m
co
-------
• centrifugation, which separates the two phases in an
enclosed vessel using centrifugal force to cause the solids
to migrate through the liquid.
Special Precautions and Limitations
As noted, removal can be limited in the presence of complexing
agents in the wastes. This problem can generally be eliminated by:
• using a sulfide precipitation agent;
• breaking up the metal complex by altering pH to either a
basic or acidic extreme and adding a substitute cation to
tie up the complexing agent when the pH is readjusted to
precipitate the metal; and
• using insoluble starch xanthate as a precipitation agent
(not widely used).
The sludge produced by precipitation should be considered haz-
ardous unless laboratory tests show otherwise.
4.3.2.4 Design Basis
The major design factors are:
• effluent criteria
• leachate flow and
• concentration of precipitable ions in the leachate.
Based on the wastewater analyses and solubility curves for the
species to be removed, laboratory tests are designed to determine
optimum precipitation conditions and chemical requirements to sat-
isfy effluent criteria.
A mixing tank is sized based on the leachate flow and precipi-
tation chemical/leachate contact time required. Generally, contact
279
-------
time ranges from 10 to 60 minutes. Flocculation tank sizes are based
on flow and retention time (typically 30 to 60 minutes). Clarifica-
tion tank size is based on laboratory experiments to determine the
settling rate and the leachate flow.
4.3.2.5 Principal Data Requirements
Leachate analysis (reagent choice, size)
• precipitable constituents
• interfering species (i.e., cyanide, EDTA, etc.)
Leachate daily average and variations on flow
Treatability study (size, reagent choice, and rate)
• optimum precipitation conditions
• settling rate
• sludge production rate
• leachate flow;
• wastewater analyses of precipitable constituents;
• wastewater analyses for constituents that interfere with
precipitation (i.e., cyanide, EDTA, etc.);
• optimum precipitation conditions;
• settling rate of precipitate; and
• sludge production rate.
4.3.2.6 Elements of Cost Review
Components
280
-------
Construction and Capital--
• tanks
• pumps
• mixers
O & M--
• chemicals
• electricity
Major Factors
process volume
Data
Sample costs for several different capacity precipitation systems
are given in Table 4-16.
4.3.3 Reduction (For Cr)
4.3.3.1 Description
Toxic hexavalent chromium ion (Cr VI) can be reduced to the less
toxic trivalent chromium ion (Cr III). The reduction process is
followed by Cr III removal through precipitation as the insoluble
sulfate. Chrome reduction is carried out by adding a reducing agent
under highly acidic conditions (of pH 2 to 3). Figure 4-13 shows a
typical flow reactor treatment process layout for Cr VI reduction.
4.3.3.2 Status
Conventional, demonstrated.
281
-------
to
00
to
TABLE 4-16
PRECIPITATION, FLOCCULATION, AND SEDIMENTATION COST ESTIMATES
AS A FUNCTION OF SIZE
Basis: -Wastewater from, Automotive Plating Operation
-Flowrate = 410,000 gpd, 350 day/year, 24 hour day
-Zinc Concentration = 113 mg/1
Capital Investment - $487,600
Treatement
Capital Investement
Variable Cost
Labor
Maintenance (4% Inv.)
Chemicals
Quicklime
Coagulant Aid
Sulfuric Acid
Electrical Energy
Total Variable Cost
Fixed Cost
Capital Recovery
Taxes and Insurance (2% Inv
Total Fixed Cost
Total Annual Cost
Unit Cost ($/1000 Gal)
82,000 gpd
$171,700
72,400
6,900
400
1,400
220
1,300
$ 82,500
27,500
.) 3,400
$ 30,900
$113,400
$ 3.95
System Size
410,000
$487,600
109,800
19,500
1,800
7,300
1,100
6,000
$145,500
78,000
9,800
$ 87,800
$233,300
$ 1.63
(Wastewater Flowrate)
gpd 2,050,000 gpd
$1,388,300
165,100
55,500
8,900
36,300
5,500
29,800
$ 301,100
222,100
27,800
$ 249,900
$ 551,000
$ .77
Source: ADL, 1976
-------
FIGURE 4-13
CHROMIUM REDUCTION TREATMENT SYSTEM
Acid Reducing Agent
Wastewater
pH = 2-3
Reduced
Wastewater
4.3.3.3 Feasibility and Effectiveness
General Features
Reducing agents include:
• SC>2 (gas)
• NaHSO-}
• FeS04
• Waste pickling liquor
Selection is most often made on cost considerations and the
availability of the reagents. Sulfuric acid is most commonly used
to acidify the solution.
283
-------
The effluent from this process must be filtered or clarified to
remove the sulfate precipitate. Neutralization will also be
required to increase the pH to acceptable levels for discharge (pH 6
to pH 9) . Residual hexavaient chromium levels can be reduced to less
than 1 ppm.
Special Precautions and Limitations
Cyanides may also be present along with hexavaient chromium. To
avoid possible release of toxic hydrogen cyanide at the low pH
(acidic) conditions necessary for reduction, cyanide removal should
always precede this treatment.
4.3.3.4 Design Basis
Design parameters are:
• Reaction tank size -- The reduction reactions are rapid. A
retention time of 5 to 15 minutes should be sufficient to
achieve thorough mixing and reduction to hexavaient chromi-
um. Tank size for the reduction system is calculated by:
VT = R x F
where;
V = tank volume
R = retention time
F = flow
Chemical requirements -- Estimates can be made by using
wastewater analysis and the general stoichiometry for each
reactant type as:
• SO2 2.5 g/gCr
• NaHS03 3 g/gCr
• FeSOi, 9 g/gCr
Laboratory reduction tests are a more accurate means of
determining reactant requirements.
284
-------
4.3.3.5 Principal Data Requirements
Leachate daily average and variations in flow rate (Chemi-
cal requirements);
Leachate analysis (reagent requirements, size)
• hexavalent chromium concentration in leachate
• pH
4.3.3.6 Elements of Cost Review
Components
Construction and Capital--
• tanks
• pumps
• mixers
• monitoring instrumentation
0 & M--
• chemicals
• electricity
Major Factors
• Process size
• Level of treatment desired
285
-------
Data
A cost example (unit and total costs) for a 2,000-gallon per day
reduction system is presented in Table 4-17.
4.3.4 Wet Air Oxidation
4.3.4.1 Description
Wet air oxidation (WAO) is a type of combustion, occurring in
the liquid phase, through addition of air at high pressures and ele-
vated temperature. The reactions take place in a reactor, which may
contain a catalyst to promote the oxidations reactions. Figure 4-14
shows a schematic of the WAO process. The products of reaction are
steam, N2 , C02 / and an oxidized liquid stream.
4.3.4.2 Status
Developmental
4.3.4.3 Feasibility and Effectiveness
General Features
The WAO process is attractive for liquid wastes containing
insufficient heat value to support self-sustaining incineration.
WAO can be self-sustaining at levels above about 15,000 ppm COD (al-
though higher levels are more typical), while conventional liquid
incineration requires levels of at least 300,000 to 400,000 ppm COD.
WAO works well on waste, too concentrated for conventional biolog-
ical treatment. Process conditions are typically:
• pressure - 24 atm (350 psi)
• temperature - 300 degrees C
• waste composition--5-15 percent oxidizable organics by
weight.
Performance capabilities of WAO are dependent on the waste
stream being treated. Destruction efficiency for ten priority pol-
lutants is shown in Table 4-18.
286
-------
Basis:
TABLE 4-17
ESTIMATED OPERATING COSTS FOR REDUCTION
- Stream Flow:
- Treatment:
- Influent Concentrations
- Effluent Concentrations:
- Raw Material Dosage
2,000 gallons per day
batch
100,000 ppm CrO (85% as Cr3+)
in 20% H0SO,
undetectable - Cr
sulfur dioxide - 240 pounds/day
lime - 2,065 pounds/day
Capital Investment - $372,600
Variable Cost
Operating Labor
Chemicals
Sulfur Dioxide
Quicklime
Total Chemical Costs
Annual
Quantity
Cost Per Unit
Quantity, 1982 $
2,500 MH
29 tons
250 tons
$19.60/hr
275/ton
31.00/ton
Annual
Cost 1982 $
$ 49,000
8,000
7,800
$ 15,800
Utilities
Electricity
Maintenance - (3% Inv.)
Total Variable Costs
35,000 kWh
$ .04/kWh
$ 1,400
11,200
$ 77,400
Fixed Costs
Taxes and Insurance (2% Inv.)
Capital Recovery (10 yrs @ 10%)
Total Fixed Costs
Total Annual Cost
Unit Cost ($/103 gal)
$ 7,500
59,900
$67,400
$144,800
$301.67
Source: ADL, 1976
287
-------
FIGURE 4-14
SCHEMATIC OF WET AIR OXIDATION
(After: Ghassemi, 1981)
High Pressure
Pump
Heat
Recovery
Discharge
Air
Pressure
Control
Valve
Compressor
The safety problems associated with the use of high presure WAO
systems require conformance to applicable operating safety codes
(e.g., ASME codes).
Special Precautions and Limitations
None noted.
4.3.4.4 Design Basis
Key design factors include (Ghassemi et al., 1981; EPA, 1982):
reactor pressure (operating pressures range from 150 to
4000 psi, typical operating pressure is 350 psi);
operating temperature (operating temperatures range from
200 to 320 degrees C, typical operating temperature is 300
degrees C) ;
288
-------
TABLE 4-18
WAO EFFICIENCY FOR TEN PRIORITY POLLUTANTS
Compound
Acenaphthene
Acrolein
Acrylonitrile
2-Chlorophenol
2, 4-Dimethyl phenol
2 , 4-Di ni trotol uene
1,2-Diphenylhydrazine
4-Nitrophenol
Pentachlorophenol
Phenol
Starting con-
centration (g/1)
7.0
8.41
8.06
12.41
8.22
10.0
5.0
10.0
5.0
10.0
% Starting material
320°C
99.96
>99.96a
99.91
99.86
99.99
99.88
99.98
99.96
99.88
99.97
destroyed
275°C
99.99
99.05
99.00b
94.96b
99.99
99.74
00.08
99.60
81.96b
99.77
aThe concentration remaining was less than the detection limit of 3 mg/1.
b
The % destruction for acrylonitrile, 2-chlorophenol, and pentachlorophenol
at 275°C were increased to 99.50, 99.88, and 97.3 by addition of cupric
sulfate (catalyst).
Source: Ghassemi, £t_ a]L. , 1981
• retention time (sample oxidation efficiencies at various
temperatures as a function of retention time are illus-
trated in Figure 4-15);
• use of catalysts; and
• use of batch on continuous system.
4.3.4.5 Principal Data Requirements
Leachate daily average and variations in flow (size)
Concentration of oxidizable materials in the wastewater
(size, air requirements); and
Treatability study (laboratory-scale):
• rates of reaction
• pressure
289
-------
FIGURE 4-15
TIME-TEMPERATURE EFFECT ON THE DEGREE OF OXIDATION
(Source: Ghassemi, et al., 1981)
0.5
1.0 1.5 2.0
Time at Temperature, Hr.
2.5
3.0
• temperature
• air addition requirements
• retention time
4.3.4.6 Elements of Cost Review
Components
Construction and Capital--
• reactor vessel (stainless steel)
• tanks
• high pressure pump
290
-------
0 & M--
• electricity
Major Factors
• process size
• operating pressure
Data
Installed capital costs is 2.0 million 1982 dollars, for a unit
capable of:
• processing 20 gallons per minute; and
reducing influent COD levels of up to 80,000 mg/1 by 80%.
Total annual operating costs for the wet air oxidation unit
described above is $148,000, 1982 dollars (Wilhelmi and Knopp,
1979) .
4.3.5 Chlorination (For Cyanide Only)
4.3.5.1 Description
Chlorination of alkaline cyanide-containing wastes removes
cyanide by oxidation in stages to the less toxic cyanate ion and then
to non-toxic bicarbonates and nitrogen. Caustic and chlorine are
added to the wastes in either a batch or flow reactor. Figure 4-16
shows a schematic of a two-stage flow reactor, a configuration often
used to minimize size or retention time by optimizing the reaction
stages through pH control.
4.3.5.2 Status
Conventional, demonstrated.
291
-------
FIGURE 4-16
CYANIDE CHLORINATION TREATMENT
Caustic Chlorine
Wastewater
ic Chlorine
Caus icChloi
1 T
Mixer
Mixer
Cyanide
Free Wastewater
Stage 1
Stage 2
4.3.5.3 Feasibility and Effectiveness
General Features
Cyanide destruction is used not only to reduce the hazard of
hydrogen cyanide gas generation under acidic conditions, but also as
a pretreatment for some heavy metal treatments, such as precipi-
tation, where cyanide complexes interfere with metal removal
(White, 1972).
Chlorination is broadly applicable to cyanide containing wastes
of highly varying composition. Residual cyanide concentrations can
be reduced to levels below 1 ppm.
System configurations include:
batch reactors
292
-------
• continuous flow reactors (preferred at flows greater than
1200 gal/hr)
Common chlorination sources are:
• chlorine gas
• sodium hypochlorite
The reaction rates are quite sensitive to pH.
Special Precautions and Limitations
The pH must be very closely monitored to avoid development of
acid conditions, under which highly toxic hydrogen cyanide gas can
be generated. Good mixing is also essential to avoid acidic
regions, even though the overall conditions remain basic. Systems
should include pH monitors, sufficient mixing power, and carefully
designed baffles for these purposes. Oxidation-reduction potential
(ORP) probes should also be installed to control chlorine additions.
Chlorine is acutely hazardous and should be handled accordingly.
Excess chlorine may react with other constituents in the waste
to form other hazardous compounds. This problem is potentially
greater in remedial action situations where waste composition may be
both poorly characterized and more variable than in conventional
industrial waste treatment applications.
4.3.5.4 Design Basis
The principal design considerations are:
• tank volume which is calculated on the basis of a retention
time of about 30 minutes per stage for a two-stage system
and flow rate is as follows:
= F(.5/hr)
293
-------
where:
V = tank volume per stage (ft3)
o
F = leachate flow (ft3/hr)
Chemical requirements which are determined by laboratory
testing.
4.3.5.5 Principal Data Requirements
Leachate daily, average and variations flow (volume)
Leachate analysis
• leachate average and variations in cyanide concen-
tration (reagent rate)
• potential for formation of hazardous chlorinated
by-products
4.3.5.6 Elements of Cost Review
Components
Construction and Capital--
• tanks
• pumps
• mixers
• monitoring instrumentation
0 & M--
294
-------
TABLE 4-19
ESTIMATED COSTS FOR CHEMICAL OXIDATION
Basis: - Stream Flow:
Treatment:
- Influent Concentrations:
- Effluent Concentrations:
- Raw Material Dosage:
Operation:
Capital Investment: $162,000
1,000 gallons per day
batch / complete oxidation
7,000 ppm copper cyanide
1,000 ppm sodium cyanide
0 ppm cyanide
NaOH 95 pounds/day
Chlorine 227 pounds/day,
240 days/year
Annual Cost per Unit
v ,, n- r--t- Quantity Quantity, 1982 $
Operating Labor 2,000 MH 19.60/MH
Chemicals
Sodium Hydroxide 11.5 tons 350/ton
Chlorine 29.5 tons 145/ton
Total Chemical Costs
Utilities
Electricity 12,000 kWh .04/kWh
Cooling Water 360 M gal 0.15/1000 gal.
Total Utilities
Maintenance @ 4% of Inv.
Total Variable Costs
Fixed Costs
Taxed Insurance @ 2% Inv.
Capital Recovery (10 yrs @ 10%)
Total Fixed Costs
Total Annual Costs
Unit Cost, $/103 Gallons
Annual Cost,
1982 $
39,200
4,000
4,300
480
50
530
6,500
54,500
3,200
26,400
29,600
84,100
350.42
Source: ADL, 1976
295
-------
• chemicals
• electricity
Major Factors
• process size
• level of treatment desired
Data
A cost example (unit and total costs) for a 1,000 gallon per day
chlorination system is presented in Table 4-19.
4.3.6 Ozonation
4.3.6.1 Description
In ozonation, contact with ozone -- a powerful oxidizing agent
-- breaks down many refractory organic compounds not treatable with
biological treatment techniques. Ozone, produced in a separate gen-
erator, is introduced to a contactor where it mixes with the wastes
and reacts with oxidizable species present.
4.3.6.2 Status
Conventional, undemonstrated.
4.3.6.3 Feasibility and Effectiveness
General Features
Ozonation is applicable only to dilute wastes, typically con-
taining less than 1 percent oxidizable materials. The destructive
power to refractory compounds may be enhanced by combining ozonation
with ultra-violet radiation (Prengle et al., 1975). Ozone is gener-
ated at low concentrations (less than 2 percent) in an air stream, at
slightly less than atmospheric pressure. Higher ozone concen-
trations are possible if oxygen is used as the gas supply.
296
-------
Ozonation is effective with:
• chlorinated hydrocarbons
• alcohols
• chlorinated aromatics
• pesticides
• cyanides
Large contactors are required because reaction rates are mass
transfer limited; ozone has only limited solubility in water. Con-
tactor depth is typically on the order of 5 meters (16 ft) to insure
adequate mixing and reaction time. Ultra-violet lamps, if used, are
operated within the contactor vessel.
Ozone is corrosive, requiring special construction materials.
Suitable materials include:
• stainless steel
• unplasticized PVC
• aluminum
• TeflonR
• chromium-plated brass or bronze.
Special Precautions and Limitations
Ozone is acutely toxic; personnel safety is, therefore, a major
concern. Modern systems are completely automated. An ozone monitor
measures ozone levels in the gaseous effluent and reduces the ozona-
tor voltage or frequency if gaseous levels exceed a preset limit
(usually 0.05 ppm). An ambient air monitor sounds an alarm and shuts
off the ozonator in the event of leaks of ozonized air. An off-gas
ozone destruction unit is also generally used in modern systems.
297
-------
4.3.6.4 Design Basis
Key design parameters include:
Ozone dose rate -- usually expressed as either ppm ozone or
pounds of ozone per pound of stream contaminants treated.
Typical dose rates are 10 to 40 ppm for the former and 1.5 to
3.0 pounds per pound of contaminant removed for the latter
(ADL, 1976).
Retention time -- typical retention times range from 10
minutes to 1 hour in several stages.
Ultra-violet light dosage -- expressed in terms of watts
per liter. Dosage should be determined by laboratory stu-
dies. Typical dosage ranges from 1 to 10 watts per liter
(Prengle, etal., 1975).
4.3.6.5 Principal Data Requirements
Leachate daily, average and variations in the flow (volume)
Concentration of oxidizable leachate analysis constituents
in the leachate
Treatability study (laboratory-scaled)
Ozone dosage
Ultra-vi
-------
• diesel generator
• pumps
• monitoring instrumentation
0 & M
• UV lamp replacement
• electricity
Major Factors
• process size
• ozone requirements
Data
Unit and total annual costs (in 1982 dollars) are estimated to be
.77$/1000 gal and $228,000 for an ozonation system capable of treat-
ing (ADL, 1976):
• 800,000 gallons per day;
• reducing influent phenol concentration of 0.38 ppm to 0.012
ppm; and
• output 190 pounds of ozone per day.
4.4 PHYSICAL TREATMENT
4.4.1 Reverse Osmosis
4.4.1.1 Description
Reverse osmosis removes contaminants from aqueous wastes by
passing the waste stream, at high pressure, through a semi-permeable
membrane. At sufficiently high pressure, usually in the range
200-400 psi, clean water passes out through the membrane leaving a
299
-------
concentrated waste stream which must be treated further or disposed
of. The high pressure counteracts the osmotic pressure of the dis-
solved wastes and acts as a driving force to concentrate the
solution, hence the name reverse osmosis. Typical membranes are
impermeable to most inorganic species and some organic compounds.
They are also impermeable to very fine particles and will remove
these as well as dissolved materials. The filtering action of mem-
branes is conventionally termed ultrafiltration.
4.4.1.2 Status
Conventional, undemonstrated.
4.4.1.3 Feasibility and Effectiveness
General Features
Reverse osmosis (RO) and ultrafiltration take place in a
cross-flow configuration. As the waste flows through a membrane
tube or bundle, the purified water flows out at right angles through
the membrane. This is different from conventional filtration where
the waste flow goes directly through the filter medium, trapping
materials on the upstream side. The cross-flow arrangement permits
high flow rates through the system.
There are three basic configurations for RO systems:
• Tubular: perforated stainless steel or porous fiberglass
tubes with liners of RO membrane, having the "active" side
facing inwards. Water is pumped at high pressures through
the tubes, and the cleaned water is collected outside the
tube.
• Spiral wound or wrap cell: a flat sheet of membrane materi-
al is wound in a spiral to produce a continuous thin channel
through which the feed flows at high laminar shear rates.
• Hollow fiber technologies: a bundle of hollow polyamide
(nylon) fibers with the "active" side of the nylon mem-
branes on the exteriors. Feedwater passes at high veloci-
ties between the fibers and fresh water is collected within
the fibers.
300
-------
Typical operating characteristics of a RO module design are
summarized in Table 4-20.
Figure 4-17 shows an illustration of various RO configurations.
Reverse osmosis is capable of removing greater than 90 percent
of TDS from wastewater streams containing up to 50,000 mg/1 TDS.
Organics with molecular weight in excess of 300 to 500, such as pes-
ticides, can be removed at efficiencies exceeding 90 percent. Oper-
ation is sensitive to wastewater pH, TSS levels and TDS levels.
The choice of membrane material, as well as configuration, is
critical to the functioning of an RO system. Cellulose acetate mem-
branes are the most common, but many others have been introduced in
recent years (see Table 4-21). Each material has a unique set of
characteristics such as cost, ease of fabrication, serviceability,
and resistance to variations in pH, temperature, and other stream
parameters.
Special Precautions and Limitations
Pretreatment is often required to handle the following condi-
tion:
Leachate variability -- Rapidly changing leachate proper-
ties such as pH, temperature and suspended solids concen-
tration can limit membrane life requiring frequent
replacement. Leachate equalization prior to the RO treat-
ment should be considered if highly variable conditions
exist.
Leachate pH -- Because membrane operation is limited to
certain pH ranges, pH adjustment should precede RO opera-
tion if necessary.
Biological Organisms -- Living organisms in leachate can
form films on RO membranes which reduces permeability.
Such organisms should be destroyed by chlorination or ozon-
ation prior to RO treatment.
TSS -- Total suspended solids can plug RO modules, partic-
ularly the hollow fiber type. Suspended solids should be
minimized to particle sizes less than about 10 microns pri-
or to introduction in most RO modules.
301
-------
FIGURE 4-17
MEMBRANE MODULE CONFIGURATIONS
(Source: Ghassemi, et al., 1981)
CASING
MEMBRANE
WATER
FLOW
a. TUBULAR MEMBRANE
ROLL TO
ASSEMBLE X'V
_ «•" si j
FEED SIDE
SPACER
FEED FLOW
X
PERMEATE FLOW
(AFTER PASSAGE
THROUGH MEMBRANE
PERMEATE OUT
PERMEATE SIDE BACKING
MATERIAL WITH MEMBRANE ON
EACH SIDE AND GLUED AROUND \
EDGES AND TO CENTER TUBE
b. SPIRAL-WOUND MODULE
SNAP RING
CONCENTRATE
OUTLET
FLOW
OPEN END
OF FIBERS
EPOXY
TUBE SHEET
POROUS
BACK-UP DISC
SNAP RING
"O" RING
SEAL
END PLATE
PERMEATE
FIBER
SHELL
POROUS FEED
DISTRIBUTOR
TUBE
"O" RING END PLATE
SEAL
C. HOLLOW-FIBER MODULE
302
-------
TABLE 4-20
COMPARISION OF REVERSE OSMOSIS MODULE CONFIGURATION
Spiral wrap
Tubular
Hollow fine fiber
OJ
o
Membrane surface area per
volume, ft2/ft3
Product water flux, gpd/ft2
Typical module factors:
Brine velocity, ft/sec
Brine channel diameter, in
100 - 300
8 - 25a
b
0.03C
40 - 100
8-25
1.5
0.5
5,000 - 10,000
0.1 - 2
0.04
0.004
Method of membrane replacement
Membrane replacement labor
High pressure limitation
Pressure drop, product water side
Pressure drop, feed to brine exit
Concentration polarization problem
Membrane cleaning - mechanical
- chemical
Particulate in feed
As a membrane module
assembly - on site
Low
Membrane compaction
Medium
Medium
Medium
No
Yes - pH and solvent
limited
Some filtration
required
As tubes - on site
High
Membrane compaction
Low
High
High
Yes
Yes - pH and solvent
limited
No problem
As entire pressure mo-
dule - on site, module
returned to factory
Medium - requires
equipment
Fiber collapse
High
Low
High
No
Yes - less restricted
Filtration required
d
Product flux varies with the net driving pressure and temperature; a flux of 10-25 gpd/ft^ is typical
at a pressure of about 400 psi.
'it is difficult to define velocity in a spiral element since the space between membrane is filled with
a polypropylene screen which acts as a spacer and turbulent promoter.
-»
"Height of brine channel (not diameter).
Permissible pH and temperature ranges dependent primarily on membrane type and not on module configura-
tion; for example, polyamide hollow fine fiber is pH limited from 4 to 11, cellulose acetate from 3 to
7.5, thin film composite (TFC) spirals have been operated and cleaned at pH levels ranging from 1 to 12.
Source: Ghassemi, et al., 1981
-------
TABLE 4-21
REVERSE OSMOSIS MEMBRANE MATERIALS
Used In General Practice
Cellulose Acetates
Cellulose Triacetate
Polyamides (Nylons)
Polysulfones
Less Common or Developmental
Cellulose Acetate/Nitrate
Aromatic Polyhydrazines
Polybenzimidazolene (PBIL)
Polybenzimidazole (PBI)
Polyep imine/Amide
Polyepiamine/Urea
Sulfonated Polyfurane
Polyethyleneamine/Urea
Polypiperazine Isophthalamide
Polyacrylonitrile
• Residual chlorine -- Because chlorine will oxidize polyam-
ide membranes, dechlorination is required.
4.4.1.4 Design Basis
Major design basis factors are:
• flow (gpd),
• solvent flux (g/cm2)(sec))
• solute flux (g/(cm2)(sec))
Flow rates are dictated by the quantity of leachate which must be
treated daily at-the site.
304
-------
Solvent flow through the RO membrane is a function of the pres-
sure applied to the RO membrane leachate treatment system and the
osmotic pressure difference between the solution at the membrane
interface and the permeate. The equation to calculate flux is:
J = K (AP - ATT)
where:
J = solvent flux (g/(cm2)(sec))
K = constant characteristic of membrane type
and operating temperature (g/cm2)(sec)(atm))
AP = applied pressure (atm) - pressure on permeate
side of membrane (atm)
ATT = osmotic pressure of solution - osmotic pressure
of permeate (atm)
Solute flux through the RO membrane can be calculated as
follows:
F = B(CH - CL)
where:
F = solute flux (g/(cm2)(sec))
3 = solute permeability coefficient (cm/sec)
CH = solute concentration on high pressure side of
membrane (g/cm3)
C = solute concentration on low pressure side of
membrane
Because solute flux is not a function of operating pressure,
higher applied pressure will produce purer solvent permeate. Most
membrane modules are operated at pressures between 350 to 600 psi.
Operation at higher pressures may cause an increase in solute flux
due to concentration polarization effects. However, continued
operation at higher pressures may compact the membrane causing a
decrease in flux. Flux decreases through the system as osmotic
pressure increases. At some point, it will become more
305
-------
cost-effective to use an alternative technique to reduce TDS
further, if needed.
4.4.1.5 Principal Data Requirements
Leachate analysis (general design data):
• hydraulic load
• TDS in solution
• osmotic pressure of solution
• solution pH
• solution temperature
• presence of oxidizing agents in solution
Treatability study (laboratory and pilot-scale)
• membrane and module type
• operating pressure
• solvent flux
• solute flux
4.4.1.6 Elements of Cost Review
Components
Construction and Capital--
• RO unit
• high pressure pump(s)
306
-------
0 & M«
• membrane replacement
• electricity
Major Factors
• RO unit size
• membrane replacement rate
Data
A cost example (unit and total) for a 3,280 gallon per day RO sys-
tem for nickel plating line rinse water are given in Table 4-22.
The nickel concentration in the influent is 2250 ppm and is
reduced to 20 ppm in the effluent. Ninety-four percent of the water
is passed through the system, and the effluent is recycled in the
rinse tank.
4.4.2 Equalization/Detention
4.4.2.1 Description
Equalization/detention smoothes fluctuations in waste quantity
flow or in waste composition. Equalization conventionally refers to
composition smoothing; detention to flow smoothing. Storage in
tanks (surge tanks) or ponds is used to average flow or concen-
tration over a period longer than the characteristic fluctuations.
Reducing variability in the waste stream avoids potential upsets of
downstream treatment processes, and may reduce costs.
4.4.2.2 Status
Conventional, demonstrated.
307
-------
TABLE 4-22
ESTIMATED REVERSE OSMOSIS PLANT COSTS
Basis: 3,280 gpd; 330 days/year operation
Estimated Investment: $19,400
Variable Costs
Labor & Maintenance
(1/4 hr/day)
Electricity
Membrane Replacement
(@ 2.5 yrs)
Total Variable Cost
Annual Cjost Per Unit Annual Cost
Quantity Quantity, 1982 $ 1982 $
82.5 MH $19.60/MH
10.725 kWh
$ .04/kWh
1,600
400
800
2,800
Fixed Costs
Capital Recovery
(10% - 10 yrs)
Total Costs
Unit Costs ($/1000 gal)
3,100
5,900
$5.45
Source: ADL, 1976
4.4.2.3 Feasibility and Effectiveness
General Features
The two basic operating modes are:
in-line equalization -- all flow passes through the equal-
ization basin.
off-line equalization -- only the flow above the average
daily flow-rate is diverted to the equalization basin, and
at low flow fed back into the main stream
308
-------
In addition to sufficient volume to accommodate fluctuations,
storage vessels must be well-mixed. Common mixing methods are
(Adams and Eckenfelder, 1974):
• baffling;
• turbine mixing; and
• aeration.
Power requirements for surface aerator to achieve adequate mix-
ing are a minimum of 15-20 hp/million gallons (Adams and
Eckenfelder, 1974).
4.4.2.4 Special Precautions and Limitations
None noted.
4.4.2.5 Design Basis
Equalization/detention design is based on:
• Leachate influent variation(S•')
• Probability of exceeding the maximum allowable
contamination level for treated effluent (S ')
These parameters are derived statistically from measurements of
influent and effluent variation. Equations for these parameters
are:
7 / ~,2
S-* .*- /-<•*• — I v /v — v^
, — O — I LI lA'A,^
* U
where:
X = average influent contaminant concentration
X- = influent contaminant concentration of sample I
n = number of samples
309
-------
and
i A — f*. \
I ma v 1
Se
/x - x\
^ _ I max I
V Y /
where:
X = maximum effluent contaminant concentration
max allowable
X = average effluent contaminant concentration
Y = confidence factor (i.e., Y=1.65 for 95%
confidence that effluent concentration will
not exceed X 95% of the time)
max
Detention time is calculated as follows:
At(S/)
. _
t —
2(S
where:
t = detention time
At = time interval of composite sample collection
Equalization/detention volume capacity is calculated as fol-
lows:
V = tF
where:
t = detention time
F = leachate flow
310
-------
4.4.2.6 Principal Data Requirements
Statistics of leachate flow and concentration:
• influent samples (a minimum of 80) gathered at a regular
frequency over a representative leachate flow period (a
minimum of ten times the time scale of unacceptable fluctu-
ations) (see Adams and Eckenfelder, 1974).
4.4.2.7 Elements of Cost Review
Components
Construction and Capital--
• basin construction
• pumps
• mixers
• aeration equipment
O & M--
• electricity
Major Factors
• basin size
• mixing and/or aeration requirements
Data
Sample costs for several different capacity equalization facili-
ties are given in Table 4-23.
311
-------
TABLE 4-23
COSTS OF EQUALIZATION FACILITIES
—
Plant
Size
mgd
1
3
10
Basin
Size
Mgal
0.32
0.88
2.40
Earthen
With
Pumping
$276,400
222,400
707,SOO
Basin
Without
Pumping
$161,000
186,700
298,900
Concrete
With
Pumping
$389,700
741,500
1,734,000
Basin
Without
Pumping
$276,400
549,800
1,325,000
Source: Research and Education Assoc., 1978
4.4.3 Ion Exchange
4.4.3.1 Description
Ion exchange is a reversible interchange of ions between an
insoluble salt or resin, in contact with wastes containing ionic
species. In the process, unwanted ionic species, principally inor-
ganic, are replaced (exchanged) with innocuous ions on the resin.
For instance, if a solution containing the salt M+x~ flows over a
cation exchange material(R~) containing a cation N+, then the fol-
lowing reversible reaction occurs:
M
+ R
N+ ± R~M+
+ N + X
Because the reaction is reversible, it is possible to regener-
ate the ion exchange resin. The overall process yields two output
streams; one main purified product stream, containing N+ and x~/ and
a small solution of the "spent" regenerant, containing a high con-
centration of the removed ions, (e.g. , M* ) .
4.4.3.2 Status
Conventional, demonstrated.
312
-------
4.4.3.3 Feasibility and Effectiveness
General Features
Most inorganic dissolved salts and some organic dissolved salts
can be removed by ion exchange. Removal efficiencies for metallic
ions are generally very high, as shown in Table 4-24, displaying
data for a typical metal-containing electroplating waste.
Removal efficiency is limited by the exchange equilibrium which
is expressed for the general reaction previously described as fol-
lows:
K = R"M+ [N+]
where:
K = equilibrium (selectivity coefficient) which
is specific for the type of resin and the
solution character
N+ = concentration of the sacrificial resin ion
species
R N = mole fraction of the removed cation on the
exchange resin
mole fraction c
on the exchange resin
_ i
R N = mole fraction of the resin sacrificial cation
M = concentration of the removal object cation
Other chemical classes which can be removed are:
inorganic anions (halides, sulfates, nitrates, and
cyanide);
organic acids (carboxyl, sulfonics, some phenols at suffi-
ciently alkaline pH);
amines, when pH is low enough to form the acid salt; and
anionic and cationic species (quaternary amines and alkyl-
sulfates).
313
-------
TABLE 4-24
REMOVAL DATA FOR ELECTROPLATING WASTEWATER STREAMS
Concentration , yg/1
Pollutant/parameter
Toxic pollutants:
Cadmium
Chromium
Chromium (+6)
Copper
Cyanide
Nickel
Silver
Zinc
Influent
5,700
3,100
7,100
4,500
9,800
6,200
1,500
15,000
Effluent
BDL
10
10
90
40
BDL
BDL
400
Percent
removal
>99
>99
>99
98
99
>99
>99
97
Below detectable limits; assumed to be <10 y/1
Source: EPA, 1980
Resins can be grouped into the following four major types:
• strong acids which remove cations in general;
• weak acids which remove cations of strong bases;
• strong bases which remove anions in general; and
• weak bases which remove anions of strong acids.
Theoretically, ion exchange processes are capable of treating
TDS concentrations up to 10,000 to 20,000 mg/1. However, practical
operations are limited to TDS concentrations less than 2,500 mg/1
because of the excessive service requirements associated with resin
regeneration at higher TDS concentrations (TRD 5) .
There are three principal ion exchange system configurations as
shown in Table 4-25.
314
-------
TABLE 4-25
ION EXCHANGE SYSTEM
Types
Cocurrent Fixed Bed
SERVICE
REGENERATION
Countercurrent Fixed Bed
SERVICE
REGENERATION
Continuous Countercurrent
SERVICE
REGENERATION I i >«—
UJ
M
Ul
Description
of Process
Indications
for Use
Advantages
Disadvantages
Downflow of raw fluid to be treated
(loading phase). Upflow backwash.
Downflow regeneration. Downflow rinse.
Batch loading and regeneration.
Low loads (200 PPM in softening; 250
TDS In demln). Lower thruput (about
1000 GPM). Where regeneration chemi-
cal cost is not critical, disposal of waste
volume In large single batch not critical,
and dilution of feed no problem. Manual
operation acceptable.
Low capital cost. Automatic controls In-
strumentation optional. Simple, basic
type of unit. Easy maintenance.
High regenerant cost. Fluctuating efflu-
ent quality. Large single batch waste
disposal. High water consumption thru
dilution and waste. Requires substantial
floor space.
Regeneration flows opposite in direction
to Influent. Backwash (In regeneration)
does not occur on every cycle to pre-
serve resin stage heights. Resin bed is
locked in place during regeneration.
Handles high loads at moderate thruput
or low loads at high thruput (GPM x IDS
or GPM x PPM removal = 40,000 or
more). Where effluent quality must be
relatively constant, regeneration cost Is
relatively critical, disposal of single
batch waste volume no problem.
Moderate capital cost. Can be operated
with periodic attention. Moderate
regeneration cost. Lesser volume of
waste due to less frequent backwash.
Consistent effluent quality.
Increased controls and Instrumentation,
higher cost. Requires mechanism to lock
resin bed. Large single batches of waste
disposal. Moderate water consmptlon
thru dilution and waste. Requires sub-
stantial floor space.
Multi-stage Countercurrent movement of
resin in closed loop providing simul-
taneous treatment, regeneration, back-
wash and rinse. Operation is only Inter-
rupted for momentary resin pulse.
Hlghloads with high thruputs (GPM x
TDS or GPM x PPM removal = 40,000 or
more). Where constant effluent quality Is
essential, regeneration costs critical,
total waste volume requires small, con-
centrated stream to be controllable.
Where loss of product thru dilution and
waste must be minimized. Where avail-
able floor space Is limited.
Lowest regeneration cost. Lowest resirr
Inventory. Consistent effluent quality.
Highest thruput to floor space. Large
capacity units factory preassembled.
Concentrated low-volume waste stream.
Can handle strong chemical solutions
and slurry. Fully automatic operation.
Requires automatic controls and instru-
mentation, higher capital cost. More
headroom required.
Source: Ghassemi, et al., 1981
-------
Special Precautions and Limitations
Operational effectiveness can be reduced by suspended solids
clogging the resin bed and/or organics fouling the resin surface.
Influents should be analyzed for these parameters and appropriate
pretreatment measures taken if necessary.
4.4.3.4 Design Basis
Important design parameters include:
• resin selection to remove pollutants of concern;
• flow rate of leachate to be treated; and
• column flow-through rate which is expressed as linear flow
[[gal] / [(min) (ft2)]] or volume flow ([gal] /(min) (ft3)]
to be used in the process. Laboratory studies are necessary
to optimize column flow-through rates. The laboratory
experiments should utilize columns with a minimum inner
diameter of one inch and a bed depth which approximates that
which will be used in field operations. Typical opera-
tional bed depths range from 1 to 3 meters. Full scale
operations can be scaled directly from laboratory results
as long as bed depth is held constant. Operation flow rates
generally range from 15 to 80 bed volumes per hour. If bed
depth is increased up to a factor 2, the overall system per-
formance improves; and
• regeneration rate required to keep system operating within
effluent specifications. Laboratory experiments are used
to determine the effluent pollutant concentration versus
number of bed volumes of solution treated. During regener-
ation, column flow-through rates typically range from .5 to
5 bed volumes per hour. The resin is usually backwashed
before regeneration to prevent a build-up of solids in the
resin. Effective backwashing requires a 50 percent bed
expansion for 15 to 20 minutes
316
-------
4.4.3.5 Principal Data Requirements
Leachate daily average and variations in flow rate:
• leachate analysis (resin selection)
• TDS concentration levels and identity
• TSS concentration
Treatability study (laboratory scale)
• column flow-through rate
• resin regeneration frequency
4.4.3.6 Elements of Cost Review
Components
Construction and Capital--
• exchanged columns
• exchange resins
• pumps
• tanks
O & M--
• resin regeneration or replacement
• electricity
Major Factors
• process size
317
-------
Data
A cost example (unit and total costs) for an 80, 000-gallon per day
ion exchange system is presented in Table 4-26.
4.4.4 Carbon Adsorption
4.4.4.1 Description
Carbon adsorption removes contaminants from aqueous wastes by
contacting the stream with a solid, activated carbon adsorbent in
granular (most common) or powdered form. Organic compounds, and
some inorganic species become bound to the surface of the carbon
particles (adsorption) and are subsequently removed along with the
adsorbent.
4.4.4.2 Status
Conventional, demonstrated.
4.4.4.3 Feasibility and Effectiveness
General Features
Carbon adsorption is used primarily to remove organic compounds
not treatable by biological treatment. This process is often used
as a polishing step following biological treatment. The combination
of the two processes appears to be a cost-effective method for
removal of a wide range of organics from aqueous wastes.
Carbon adsorption technology is applicable to dissolved organ-
ics, generally. Many organics can be reduced to the one to ten^g/l
level. Results of an EPA study showed that 51 of 60 toxic organic
compounds could be removed (EPA, 1980). Some inorganic species,
such as antimony, arsenic, bismuth, chromium, tin, silver, mercury,
and cobalt are partially absorbed (EPA, 1982). Conventional water
quality parameters (BOD, COD, TOG) are also reduced by carbon
adsorption; the performance level is dependent on the specific waste
stream characteristics.
318
-------
TABLE 4-26
ION EXCHANGE COST ESTIMATES
Co
i—<
IO
Capital Investment: $648,000
Basis: 80,000 gallons/day
24 hour/day 350 days/year
3 bed system, in duplicate for regeneration
24-hour loading time
Variable Cost
Operating Labor
Chemicals
Resin Replacement (20%/yr)
- NaOH (70%)
- H2S04 (98%)
Total Chemicals
Utilities (Electricity)
Maintenance (3% of Inv.)
Total Variable Costs
Fixed Costs
Taxes & Insurance (2% Inv. )
Capital Recovery (10 years @ 10%)
Total Fixed Costs
Total Costs
3
Unit Costs ($/10 gallons)
Annual Cost Per Unit Annual
Quantity Quantity, 1982 $ Cost 1982 $
2,200 MH $19.60/MH $ 43,100
4,200
175 tons 350.00/ton 61,200
48 tons 83.90/ton 4,000
$ 69,400
75,000 kWh .04/kWh 3,000
19,400
$134,900
$ 13,000
104,800
$117,800
$252,700
$ 9.03
Source: ADL, 1976
-------
Although there is no theoretical, technical upper limit for the
concentration of adsorbable organics in the waste stream; economics
in conventional systems generally dictate a practical limit of about
one percent. Hazardous wastes, quite frequently, contain organics
in excess of one percent. Even so, carbon adsorption may be
cost-effective since the economic premises for remedial action are
very different from those of conventional wastewater treatment.
The removal process configuration for the two forms of carbons
is quite different.
• Granular Activated Carbon — Contact between the adsorbent
and the waste stream occurs in a moving bed reactor or in
fixed bed reactors coupled in several possible configura-
tions as shown in Figure 4-18.
Periodically, when the carbon adsorption capacity is
exhausted, fresh or regenerated carbon is added, replacing
the spent adsorbent. The used carbon is removed for dis-
posal, destruction or regeneration.
• Powdered Activated Carbon -- Finely ground carbon is mixed
with the wastewaters, and, after sufficient time for the
adsorption to occur, is removed and disposed of. The pow-
dered form of carbon is not regenerated. The carbon is gen-
erally added to the clarifier of the biological treatment
system, but may alternatively be added directly to a sludge
aeration tank. The spent carbon containing the adsorbed
contaminants is removed along with the excess sludge. Pow-
dered carbon may improve the settleability of the sludge in
addition to its primary adsorbent function. A combined
activated sludge, powdered activated carbon system is capa-
ble of reducing BOD and COD levels which would, normally,
overload a conventional activated sludge system (EPA,
1980).
The choice of system configuration for both granular and pow-
dered carbon depends on many factors. Table 4-27 presents a summary
of the primary determinants. The flow direction depends on the spe-
cific application. Downflow systems can accommodate higher sus-
pended solids concentrations (i.e., 65-70 mg/1) if the liquid
viscosity is similar to that of water. Solids are filtered out and
the column requires periodic backwashing. Upflow systems can handle
more viscous liquids and require less bed washing. The most common-
ly used contact method is a flow-through column system.
320
-------
FIGURE 4-18
GRANULAR ACTIVATED CARBON SYSTEM CONFIGURATION
(Source: ADL, 1976)
Moving Bed Down Flow in Series
out
in
1
Down Flow in Parallel
Upflow-Expanded in Series
N>
t
t
'.. •..*
t
':::::':
out
out
Counter-current carbon use • Counter-current carbon use
Prior suspended solids removal • Maximum linear velocity
Small volume systems • Large volume systems
Filtration and adsorption capability
Maximum linear velocity
Large volume systems
• Counter-current carbon use
• Minimum head loss
• Minimum pretreatment
-------
TABLE 4-27
CONTACTING SYSTEMS
Method
Application Conditions
Comments
Single or parallel
adsorbers
OJ
Adsorbers in series
Expanded upflow
adsorber(s)
Moving bed
Powdered carbon with
subsequent clarifier and/
or filter
Powdered activated carbon
with activated sludge
•Pollutant breakthrough curve is steep.
•Carbon recharge interval is long.
•Volume flow is high.
•Influent is viscous.
•Pollutant breakthrough curve is gradual.
•Uninterrupted operation is necessary.
* Relatively low effluent concentration
is required.
•Carbon recharge interval is short.
• For high flows and high suspended solids
concentrations.
•For systems requiring
efficient use of carbon (i.e., carbon
adsorption capacity is exhausted before
removal from column).
•Carbon useage higher than for series of
fixed-bed adsorbers.
• Influent concentration of pollutants
should be relatively constant to avoid
frequent sampling and adjustment of
carbon dosage.
• For activated sludge systems receiving
toxic or shock organic loadings.
• Typical flows are 1 to 4gpm/ft .
•Parallel system is usually selected if
pressure drop problems are expected for
the system,
•Moderate adsorbent expense.
• Typical flows are 3-7gpm/ft
•High adsorbent expense.
• Typical flows are 5-9gpm/ft .
• Suspended solids are passed through the
column and not separated.
• Influent must contain less than 10mg/l
TSS, and not biologically active.
Either parameter will cause a pressure
drop in the system and necessitate
removal of carbon prior exhaustion of its
absorption capacity.
•No restrictions or suspended solids or
oil and grease in influent.
•Capital equipment costs relatively low.
•Simple to operate.
• Protects the biological system from toxic
organics and shock loadings. Generally
improves effluent quality.
Source: ADL, 1976
-------
Regeneration of spent carbon may be accomplished by a variety of
means, the most common involving thermal destruction of the adsorbed
organics in a multiple hearth furnace. About 5 to 10 percent of the
carbon is lost in this (and most other) regeneration process due to
the creation of fines from the mechanical handling of the carbon.
Other regeneration processes include thermal treatment with steam,
extraction of adsorbed organics with solvents (including acids,
bases, and super critical fluids), and biological degradation of the
adsorbed material.
Special Precautions and Limitations
Carbon adsorption system performance is sensitive to the compo-
sition of the influent and flow variations. Because a system design
based on good data can perform poorly if influent conditions change,
systems are generally oversized. If influent composition is
expected to vary significantly, an equalization tank preceding the
carbon adsorption system may be necessary. For fixed-bed, granular
carbon systems special attention must be given to the materials of
construction (to prevent corrosion and mechanical failure) and to
the materials handling equipment (pipes, pumps, valves, controls)
for the transfer of carbon to and from various tanks and/or regener-
ation units.
Care must be taken to insure that the adsorption capacity of the
carbon is not reduced either by chemicals, resins, or fine precipi-
tates in the influent, or by the continued presence of similar chem-
icals in the residual water (after draining) if the carbon is
thermally regenerated. In the latter case, any material (e.g, inor-
ganic salts, some resins) that are not volitalized or combusted dur-
ing regeneration will remain in the pores of the carbon resulting in
an irreversible loss of adsorption capacity.
In all cases, it is prudent to consider the possibility of
biological activity in the carbon system. Such activity can help
(via pollutant biodegradation) or hinder (via clogging and/or odor
generation) the process. Suspended solids and oil/grease can inter-
fere with carbon adsorption treatment. Influent concentrations of
these pollutants should not exceed 50 ppm and 10 ppm, respectively
(ADL, 1976).
4.4.4.4 Design Basis
The type of activated carbon to be used is a primary design con-
323
-------
sideration. Several commercial carbons are available. The products
differ in physical properties such as pore size, surface area, and
adsorption characteristics. Some commercial carbons are listed in
Table 4-28.
Carbon selection requires laboratory testing of carbon adsorp-
tion capacities for the specific waste stream to be treated. Both
equilibrium adsorption isotherms and carbon column breakthrough
curves should be determined.
For adsorption isotherms, the general test procedure is to mix
batches of wastewater with quantities of activated carbon and ana-
lyze the equilibrium conditions. If the full-scale treatment system
will include carbon regeneration, then activated carbon which has
been regenerated several times should be used. If virgin carbon is
used, then a carbon with undersized pore size could be selected
because carbon surface area associated the smaller pores and pure
volumes are reduced by regeneration (Schweitzer, 1979). Laboratory
results of the pollutant adsorbed to carbon ratio (wt/wt basis) are
plotted against the pollutant equilibrium concentration (mg/1) on
log/log paper as shown in Figure 4-19. Temperature and pH effects
can be studied with this experimental technique. Based on the
graphical comparison of adsorption efficiencies, the appropriate
carbon type can be chosen to meet effluent criteria.
Design parameters are a function of the organic load, hydraulic
load, contact method, and contact time. A summary of contact meth-
ods and their typical operation applications is provided in Table
4-28.
It is not possible to use carbon adsorption isotherms to predict
full-scale contactor behavior. Contactor design must be optimized
by laboratory testing, conventionally using a method known as
bed-depth/service time analysis (BDST) (Adams and Eckenfelder,
1974) . Typically, three to four columns of equal bed depth are oper-
ated in series. Bed depths usually range from 4 ft to 20 ft.
Hydraulic load rates should simulate field operating conditions
which are usually 2-10 gpm/ft2. Effluent from each column is ana-
lyzed for a target parameter such as total organic carbon (TOG) . The
effluent-to-influent adsorbable TOC concentration ratio is plotted
as a function of bed volumes treated, as shown in Figure 4-20. The
data shown in Figure 4-20 can be represented as service time versus
bed depth for various removal efficiency levels as shown in Figure
4-21.
324
-------
TABLE 4-28
PROPERTIES OF SEVERAL COMMERCIALLY AVAILABLE CARBONS
PHYSICAL PROPERTIES
Surface area, m^/gm (BET)
Apparent density, gm/cc
ICI
AMERICA
HYDRODARCO
3000
600-650
0.43
CALGON
FILTRASORB
300
(8x30)
950-1050
0.48
WESTVACO
NUCHAR
WV-L
(8x30)
1000
0.48
WITCO
517
(12x30)
1050
0.48
Density, backwashed and drained.
Ib/cu ft
Real density, gm/cc
Particle density, gm/cc
Effective size, mm
Uniformity coefficient
Pore volume, cc/gm
Mean particle diameter, mm
SPECIFICATIONS
Sieve size (U.S. std. series)
Larger than No. 8 (max.
Larger than No. 12 (max.
Smaller than No. 30 (max.
Smaller than No. 40 (max.
Iodine No.
Abrasion No., minimum
Ash (%)
Moisture as packed (max. %)
22
2.0
1.4-1.5
0.8-0.9
1.7
0.95
1.6
%> 8
%) c
%) 5
%) c
650
b
b
b
a' Other sizes of carbon are available on request from
b No available data from the
c Not applicable to this size
manufacturer.
carbon.
26
2.1
1.3-1.4
0.8-0.9
1 .9 or less
0.85
1.5-1.7
8
c
5
c
900
70
8
2
the manufacturers.
26
2.1
1.4
0.85-1.05
1.8 or less
0.85
1.5-1.7
8
c
5
c
950
70
7.5
2
30
2.1
0.92
0.89
1.44
0.60
1.2
c
5
5
c
1000
85
0.5
1
Source: ADL, 1976
325
-------
FIGURE 4-19
SCHEMATIC OF CARBON ADSORPTION ISOTHERM
(Source: Adams and Eckenfelder, 1974)
Used by permission, see Copyright Notice
10
Carbon A
Carbon C
Carbon B
.c
O)
.01
10 100 1000
COD Concentration in Aqueous Phase Equilibrium (mg COD/1)
The full-scale system can be designed based on the BDST data.
Because BDST results are sensitive to hydraulic load rate and pollu-
tant concentration levels, these parameters should reflect antic-
ipated field conditions in the testing program. A series system is
sized so that as the first column's adsorptive capacity is
exhausted, the effluent from the last column is approaching the
defined pollutant limitations. For a moving bed system where 5 per-
cent of the carbon should be periodically removed, total bed depth
is designed so that as the bottom 5 percent of the carbon is
exhausted, the effluent is approaching the defined pollutant limi-
tations. A sample sizing calculation for a moving bed system and a
series system based on the BDST curves is shown in Figure 4-21.
The carbon usage rate is equal to the service time multiplied by
the quantity replaced following each servicing. For example, carbon
use for a series system is calculated by:
326
-------
FIGURE 4-20
SCHEMATIC BREAKTHROUGH CURVES FOR COLUMNS IN SERIES
(Source: Adams and Eckenfelder, 1974)
Used by permission, see Copyright Notice
c
-------
FIGURE 4-21
SCHEMATIC OF BED DEPTH VERSUS SERVICE TIME
(After: Adams and Eckenfelder, 1974)
20 h
15 -
CO
(D
E
p
CD
CO
10 -
90% Breakthrough
4.5 day service time to replace 5% of
carbon in moving bed systems
10% Breakthrough
10
15
Bed Depth
20
25
3.5 (Ib/hr-ft2)
application; and
for regeneration of industrial carbon
4.7 (Ib/hr-ft^) for regeneration of municipal treatment
carbon application.
Regeneration rates may vary considerably for specific treatment
applications. The regeneration capacity required can be calculated
by dividing the carbon recharge quantity by the service interval as
follows:
Regeneration capacity = Carbon charge (lb)
^ •* Service time (hr)
328
-------
It is common practice to specify a regeneration capacity up to
twice the amount actually needed in order to allow for unscheduled
maintenance.
4.4.4.5 Principal Data Requirements
Leachate daily average flow rate (bed cross-sectional area)
Leachate analysis (service time)
• influent concentrations
Carbon selection (batch equilibrium adsorption isotherm
tests)
• carbon loss during one regeneration cycle (if
regeneration is included in design)
• physical properties, bulk density
Bed depth - service time (BDST) (laboratory column tests)
• hydraulic loading (flow per unit area) usually 2-8
gpm/f t2.
• organic removal rate
• backwash hudraulic loading (if backwashing is
included in design)
• adsorption efficiency
• adsorption rate constant
4.4.4.6 Elements of Cost Review
Components
Construction and Capital--
carbon columns
329
-------
• reactivation equipment
• pumps
0 & M—•
• carbon regeneration and/or replacement
• electricity
Major Factors
• process size
• carbon exhaustion rate
Data
Construction and 0 & M costs are shown in Figures 4-22 and 4-23,
respectively.
A cost example for a 100,000 gallon per day carbon adsorption
unit designed to treat influent containing 1,000 ppm phenol is given
in Table 4-29.
4.4.5 Stripping
4.4.5.1 Description
Stripping removes volatile contaminants from an aqueous waste
stream by passing air or steam through the wastes. With air, the
volatile, dissolved gases are transferred to the air streams for
treatment such as carbon adsorption or thermal oxidation. With
steam the process is, in essence, a steam distillation of the waste
with the volatile contaminants ending up in the distillate for
treatment. Typical system configurations are shown in Figures 4-24
and 4-25.
330
-------
FIGURE 4-22
CONSTRUCTION COSTS FOR TERTIARY
ACTIVATED CARBON TREATMENT
(1976 COSTS)a
(Source: EPA, 1982)
FIGURE 4-23
O&M COSTS FOR TERTIARY ACTIVATED
CARBON TREATMENT (1976 COSTS)3
(Source: EPA, 1982)
CONSTRUCTION COST
100
10
&
o
£
o
1 0
0 1
0.1
1.0 10
Wastewater Flow. Mgal/d
100
OPERATION & MAINTENANCE COST
10
1 0
0 1
001
0.]
J
r
>
>
L
.yr
s
s
*
7
1.0
p
X
,'•
x
10 1C
Wastewater Flow. Mgal/d
ato adjust costs to 1982 dollars, multiply by 1.62. ato adjust costs to 1982 dollars, multiply by 1.74.
331
-------
TABLE 4-29
ESTIMATED COSTS FOR ACTIVATED CARBON REMOVAL OF PHENOL
S3
Basis: 100,000 gpd, 1,000 ppm Phenol; 330 days/yr operation.
Estimated Investment: $1,944,000
1 Annual Cost Per Unit
Variable Costs Quantity Quantity, 1982 $
Labor 11,500 MH $19.60/MH
Maintenance (5% of Inv)
3
Electricity 700 x 10 kWh .04/kWh
Steam 2.35 x 106lb 7.50/103lb
Fuel 17.5 x 109 Btu 5.00/106Btu
Make-up Carbon 174 x 1Q3 lb 1.00/lb
Total Variable Costs
Fixed Costs
Taxes and Insurance (2% of Inv)
Capital Recovery (10%-10 yrs)
Total Fixed Costs
Total Costs
Unit Cost - ($/1000 gallons)
Unit Cost - ($/lb of Phenol)
/
Annual Cost
1982 $
$225,400
97,200
28,000
17,600
87,500
174,000
$692,700
$ 38,900
315,900
$354,800
$984,500
$29.83
$3.58
Source: ADL, 1976
-------
FIGURE 4-24
AIR STRIPPING TOWERS
(Source: EPA, 1982)
AIR OUTLET
WATER
INLET
AIR
INLET*"
WATER
OUTLET
WATER INLET
AIR INLET
COLLECTION BASIN
FAN
CROSS-FLOW TOWER
AIR
OUTLET
WATER
INLET
AIR INLET
DRIFT
ELIMINATORS
DISTRIBUTION
SYSTEM
AIR INLET
WATER
COLLECTING BASIN
COUNTERCURRENT TOWER
4.4.5.2 Status
Conventional, demonstrated. Air stripping has been used for
trihalomethane and TCE removal.
4.4.5.3 Feasibility and Effectiveness
333
-------
FIGURE 4-25
TYPICAL STEAM STRIPPING SYSTEM
(Source: ADL, 1976)
Condenser
-—Q-
*• Concentrated
Vapors
• Steam
General Features
Both versions of stripping are capable of high removal effi-
ciencies. Air stripping of ammonia from wastewaters has exceeded 90
percent for influent ammonia concentrations of less than 100 ppm
(ADL, 1976), and 99+ percent has been achieved for removal of, TCE
from groundwater.
Steam stripping can be applied to:
volatile organic compounds (phenol, vinyl chloride, etc.)
water-immiscible compounds (chlorinated hydrocarbons,
etc. )
ammonia
334
-------
• hydrogen sulfide
Removal efficiencies of volatile organic compounds from waste-
waters ranging from 10 percent to 99 percent have been reported
(EPA, 1980).
Special Precautions and Limitations
Air stripping has been demonstrated only for ammonia in cooling
tower systems.
Both air and steam stripping pose potential air pollution prob-
lems if volatile organic compounds are present in the leachate. Air
pollution problems can be prevented by using emission control
devices (e.g, condenses, carbon adsorption filters) and maintaining
proper operating conditions in the system.
4.4.5.4 Design Basis
Design parameters for air and steam stripping are site
specific. The following design specifications are presented for
illustrative purposes.
Air Stripping (ADL, 1977)
Hydraulic Load: 40 1/mm/m2 (gpm/ft2)
Air Flow: 3 m3/! (400 ft3/gal)
Depth of "Packing": 8 m (25 ft)
Operating Temperature: 16 - 40°C
Operating Wastewater pH: 11 - 12
Treatment Levels (effluent criteria)
Steam Stripping (EPA, 1980)
Wastewater Flow: 760 1/min (200 gpm)
Steam Requirement: .07 - .24 kg/1 (0.6 - 2.0 Ib/gal)
335
-------
Column Height: 6 - 18 m
Colum Diameter: 1 - 3m
4.4.5.5 Principal Data Requirements
Air Stripping
Leachate daily average and peak flow (column length)
Leachate analysis (gas flow)
• temperature
• strippable component concentration
Column or tower packing characteristics (manufacturer's
data)
• pressure drop
• height of transfer unit
Steam Stripping
Same as for air stripping.
4.4.5.6 Elements of Cost Review
Components
Construction and Capital--
Air
• packing tower
336
-------
• fans
• rapid mix tanks
• pumps
Steam
• packing tower
• reboiler
• reflux condenser
• tank(s)
• pump(s)
• heat exchanger
0 & M—
• steam
• electricity
• cooling water
Major Factors
• process size
• process size
• steam requirements
Data
Capital and operating cost for an ammonia stripping unit are
shown in Figures 4-26 and 4-27, respectively.
Capital and operating cost are given for a 200-gallon per day
steam stripper are shown in Tables 4-30 and 4-31, respectively.
337
-------
FIGURE 4-26
FIGURE 4-27
CAPITAL COSTS OF
AMMONIA STRIPPING SYSTEM
(Source: EPA, 1982)
Construction Cost
OPERATION AND MAINTENANCE COSTS
OF AMMONIA STRIPPING SYSTEM
(Source: EPA, 1982)
IU
1.0
0.1
0.01
0
^
,>
.1
1 1
'
X
t
1.0
^_
• '
f
—
f
J
Z H
10
100
e
s.
•S
g 5
I 2
o
"S
c
1.0
Operation & Maintenance Cost
0.01
o
«
ID
'I
ID
0.001
Wastewater Flow, Mgal/d
0.1 1.0 10
Wastewater Flow, Mgal/d
100
Includes: Related Yardwork; Engineering, Legal,
Fiscal, and Financing Costs During Construction,
and Excluding Cost/of pH Adjustment. Based on
1 gpm/sf of Tower Packing, 24 ft Packing Depth.
Includes Influent Pumping (TDH = 50 ft).a
Excludes: Cost of pH Adjustment; Labor Fixed
@ 59/hour, Power @ $0.02/kWh.a
to update costs to 1982 dollars, multiply by 1.62.
ato update costs to 1982 dollars, multiply by:
labor-1.64
power—2.0
materials-1.52
338
-------
TABLE 4-30
CAPITAL INVESTMENT FOR A 200 GPM STEAM STRIPPER a
Purchased Equipment
1982, $
Feed Pump 200 gpm @130 ft head $ 6,280
Feed Pump 200 gpm @ 60 ft head 2,830
Feed Heat Exchanger 800 sq. ft. 31,400
Distillation Column 24 trays,
6 ft. diameter x 60 ft. 219,800
Condenser - 400 sq ft 18,800
Condensate Tank - 1,000 gal 6,280
Total Purchased Equipment $285,400
Total Capital Investment $1,377,000
aAll equipment 304 stainless steel.
Source: ADL, 1976
4.4.6 Sedimentation
4.4.6.1 Description
Sedimentation removes suspended hazardous components from
aqueous solution by permitting the particles to settle to the bottom
of a vessel through the action of gravity.
4.4.6.2 Status
Conventional, demonstrated.
4.4.6.3 Feasibility and Effectiveness
339
-------
TABLE 4-31
OPERATING COSTS FOR A 200 GPM SOUR WATER STEAM STRIPPER
Basis: - 200 gpm sour water containing 5% by weight (NH ) S.
- 350 days/yr, 24 hr/day.
Capital Investment: $1,377,000- 100 MM gal/yr
Variable Costs
Operating Labor
(2m-h/shift)
Steam
Electrical Energy
Cooling Water
Maintenance (5% of Inv.)
Total Variable Cost
Fixed Costs
Annual
Quantity
Cost Per
Unit Quantity Annual Cost
1982 $ 1982 $
Capital Recovery
(10 yrs at 10%)
Taxes and Insurance
(at 2% cap. inv./yr)
Total Fixed Costs
Total Operating Cost
Unit Cost ($/l,000 gal)
$2100
$ 19.60
41,200
8
2 x 10 Ib
1.7 x 10 kWh
7.50/1,000 1,500,000
Ib
.04/kWh 6,800
1.2 x 10 gal .15/1,000
gal
180,000
68,900
1,796,900
223,600
27,500
$ 251,100
$2,048,000
$ 21.36
Source: ADL, 1976
340
-------
General Features
flocculating agents, producing agglomerates of individual free
particles, are often used to enhance the settling action. In con-
ventional industrial waste applications, sedimentation can reduce
waste TSS loadings to 10 to 200 mg/1, corresponding to a removal
efficiency of 90-99 percent for typical wastes. There is no limita-
tion on influent concentrations in this method.
Operating modes are:
• Batch
• Continuous (most common)
Settling tanks generally have conical bottoms with sludge
removal at the apex. Baffles are often installed to maintain quies-
cent conditions and prevent reentrainment of settling particles.
Design should include:
• adequate volume for surge flow
• adequate flocculation time (30-60 minutes)
Special Precautions and Limitations
None noted.
4.4.6.4 Design Basis
Key design factors are (Schweitzer, 1979):
• solids handling capacity or unit area
(lb/[(hr)(ft2)])
• overflow rate - typical loading rates are:
- 500 - 600 gpd/ft2 for alum treated wastewater
341
-------
- 700 - 800 gpd/ft2 for iron treated wastewater
- 1400 - 1600 gpd/ft2 for lime treated wastewater
• retention time - velocity of wastewater through
the sedimentation tank should be in the range of
0.5 and 3 ft/minute
• weir loading - typical loading rates are
10,000 - 40,000 gpd/ft (Metcalf and Eddy,1979)
4.4.6.5 Principal Data Requirements
Leachate daily average flow (area)
Settling velocity (area, through-put), laboratory study or
can be estimated from leachate characteristics for parti-
cles greater than 0.02mm in diameter)(Schweitzer, 1979).
Leachate analysis (area, through-put)
• size distribution
• solids specific gravity
• liquid specific gravity
4.4.6.6 Elements of Cost Review
See Precipitation
4.4.7 Dissolved Air Flotation
4.4.7.1 Description
Dissolved air flotation removes insoluble hazardous components
present as suspended fine particles or globules of oils and greases
from an aqueous phase. In this technique aqueous waste mixtures are
first saturated with air at high pressures and then moved into tanks
under atmospheric pressure. The reduction of pressure causes small
bubbles of air to form and rise to the surface. The rising bubbles
342
-------
carry the fine particles and small globules of oil or grease to the
surface where they are skimmed off.
4.4.7.2 Status
Conventional, demonstrated.
4.4.7.3 Feasibility and Effectiveness
General Features
Flotation can be used on suspended wastes of density close to
that of water (1.0 g/1). The addition of surface active chemicals
and pH adjustment are often used to enhance the sweeping action of
the bubbles and the skimming operation. In industrial practice,
with wastes containing TSS and oil or grease levels up to 900 mg/1,
removal efficiency of 90 percent has been recorded (EPA, 1980).
Special Precautions and Limitations
If the stream contains volatile organic constituents, air emis-
sions resulting from stripping during the flotation process could
become a problem and may require additional treatment controls, such
as those used for air emission control.
4.4.7.4 Design Basis
Major design variables and corresponding operating conditions are
(Adams & Eckenfelder, 1974):
• System pressure, 40-60 PSIG;
• Recycle flow, 30%-40% for oily waste;
Q (A*/S)
R =
C [f(P/14.7 + D-l]
s
343
-------
where:
R = recycle flow
Q = influent flow (mgd)
A*/S = air supply to waste water solids ratio (Ib/lb)
X = average influent suspended solids concentration
(mg/1)
C = gas saturation at atmospheric conditions (mg/1)
s
f = fraction of theoretical saturation (-v.80)
P = pressure (psi)
and:
A* = R Cs [f(P/14.7 + !)-!](8. 34)
• Hydraulic loading, 1-4 gpm/ft2 ; and
• Retention period, 20-40 minutes.
It is common engineering practice to triple the calculated A* to
provide a safety factor and excess air for high dissolution effi-
ciency.
The hydraulic loading rate (referred to as surface loading rate
(SLR)) is determined by plotting laboratory experimental values of
effluent pollutant concentrations versus surface loading rates.
The rate which is sufficient to achieve effluent water quality goals
is identified from the graph.
The retention time equation is:
t ~
where a depth of 4 to 9 feet is typically chosen
(EPA, 1980)
344
-------
4.4.7.5 Principal Data Requirements
Required, design information includes (Adams and Eckenfelder,
1974):
Leachate daily average flow (system volume)
Leachate temperature (recycle flow)
Leachate oil/grease or suspended solids concentration (re-
cycle flow)
Treatability tests (air requirements, pressure)
• rise rate
• A*/S ratio
• hydraulic loading rate (surface loading rate)
4.4.7.6 Elements of Cost Review
Components
Construction and Capital--
• flotation basin
• aerator
• pumps
• pressure tanks
• skimming equipment
O & M--
• electricity
• solids removal
345
-------
Major Factors
• Surface area of flotation basin
• Hydraulic loading
Data
Capital cost for a dissolved air flotation system with a
200-square foot surface area is approximately $63,000 (1982
dollars)(Adams and Eckenfelder, 1974).
4.4.8 Filtration
4.4.8.1 Description
Filtration is a physical means of separating solids from liq-
uids (and vice versa) by forcing the fluid through a porous medium.
For hazardous waste, filtration can serve two separate objectives:
• removal of suspended solids from a liquid stream for the
purpose of producing a purified liquid; or
• volume reduction of waste sludges by increasing the solids
concentration by removing the liquid (sludge dewatering).
This discussion applies to particulates greater than 25 microns
in diameter. Waste particulates greater than about 25 microns in
diameter are trapped at the surface or within the porous filter
medium as the fluids flow through. Smaller particles must be
agglomerated. In all filtration systems pressure or suction is
required to force the fluid through the filter, as is some means to
remove the trapped solids.
4.4.8.2 Status
Conventional, demonstrated.
4.4.8.3 Feasibility and Effectiveness
346
-------
General Features
Any liquid with riiterabie solids can be treated. Filtration is
also applicable to aqueous liquids containing droplets of another
immiscible liquid phase such as oil-contaminated water. Filtration
is often used on sludges or liquids generated during other waste
treatment processes.
There are three major filtration system types:
• granular media filter
• rotary drum vacuum filter
• filter press.
Granular media filters (Figure 4-28) are widely used for sepa-
rating suspended solids from aqueous liquid streams. The granular
media (usually sand or sand and coke) is contained in a basin
equipped with an underdrain. Water drains through either by gravity
or due to applied pressure. As the bed clogs with solids, the filter
medium is backwashed, dislodging the solids, the backwashed water is
a small volume of liquid from which solids can be removed by floccu-
lation and/or sedimentation.
In rotary drum vacuum filters (Figure 4-29) the filter medium is
a fabric or wire mesh belt stretched over a drum and a small roller.
The drum is partially immersed in the liquid to be filtered. A vacu-
um applied to the inside of the drum draws the liquid through, and
the liquid is collected from within; the solids trapped on the fil-
ter cloth are scraped off as the belt is rotated out of the liquid
and past a scraping device.
A filter press (Figure 4-30) consists of a series of plates and
screens. Referring to the figure, liquid is introduced in the "B"
cavity; pressed against this cavity are plates "A" and "B" which are
perforated metal sheets covered with a fabric filter medium. The
plates and frames are pressed together forcing the liquid out of
cavity "B" while trapping solids. Filter presses treat sludge of a
similar nature to that treated by rotary drums. They also dewater
gelatinous and sticky sludges which are often difficult to treat.
Table 4-32 shows the applicability of these different types of
filtration systems to various waste forms.
347
-------
FIGURE 4-28
GRANULAR MEDIA FILTER
(Source: ADL, 1976)
Filtration Cycle
Bed of Filter Media
Underdrain Plate
With Strainers \
. a ? ' ' '« ' * "o '* * ° ° ° '
.e-D-
» . .
W^rr
Backwash Wastewater
Wash water Supply
3X1 )—*-
Open Filtered Effluent
Backwash Cycle
Filter Media Bed Becomes
Fluidized And Turbulent
During The Backwash Cycle
:le\
'/»•'/ \/ ,»'*'"•
' ii. >\ ',///''>/,
^^yiv-^AV^vrH/rv-v^
Spent Backwash Water
Wash water
Closed
348
-------
FIGURE 4-29
ROTARY DRUM VACUUM FILTER
(Cross-Sectional Side View)
(Source: ADL, 1976)
Fabric or Wire Filter Media
Stretched Over Revolving
Drum
Roller
Direction of Rotation
CO
4>
VO
Solids Scraped off
Filter Media
Vacuum Source
»_ Steel Cylindrical
Frame
Liquid Force
Through Media
By Means of
Vacuum
Liquid To be Filtered
Solids Collection Hopper
\
Trough
Filtered Liquid
-------
FIGURE 4-30
FILTER PRESS
(Illustrative Cross-Sectional View of One Rectangular Chamber)
(Source: ADL, 1976)
Perforated Backing Plate
Fabric Filter Medium
Inlet Liquid to be
Filtered
Fabric Filter Medium
Solid Rectangular
End Plate
Entrapped Solids
Plates And Frames Are Pressed
Together During Filtration Cycle
Rectangular Metal Plate
Rectangular Frame
Filtered Liquid Outlet
When the cavity formed between plates A and C is filled with solids, the plates are separated.
The solids are than removed and the medium is washed clean.
The plates are than pressed together and filtration resumed.
350
-------
TABLE 4-32
POTENTIAL APPLICABILITY OF FILTRATION
TO VARIOUS FORMS OF HAZARDOUS WASTES
Waste Form
Aqueous
Non-Aqueous Liquid
Slurries
Sludges
Granular
Media Filters
High
Moderate
Low
Low
Rotary Drum
Vacuum Filters
High
Moderate/high
High
High
Filter
Presses
High
Moderate/high
High
High
Source: ADL, 1976
Table 4-33 shows typical operating conditions. Effluent char-
acteristics are typically:
Granular Filter Media -- suspended solids in effluent can
be as low as 1-10 mg/1.
Rotary Drum Vacuum Filter -- sludges dewatered to a solids
concentration of 10-40 percent, filtrate still retains
several thousand mg/1 suspended solids.
Filter Press -- sludges dewatered to 15-50 percent solids
concentration; filtrate contains several thousand mg/1
suspended solids.
Special Precautions and Limitations
Variability of solids content in remedial action applications
may cause clogging and reduce the overall operating efficiency.
The liquid effluent from hazardous waste sludge dewatering may
contain hazardous materials and then require treatment before dis-
posal. Laboratory tests should be performed to determine the extent
of this type of potential problem.
351
-------
TABLE 4-33
MAJOR DESIGN AND PERFORMANCE VARIABLES FOR FILTRATION
Granular
Filter
Media
Filter
Presses
Rotary Drum
Vacuum Filters
Solid Content-Influent
(mg/L or % by weight)
Pressure Differential
Waste Throughput
<200
Usual gravity
80-250 L/min/m2
17 atm
1-10 kg/
nr/hr
(solids-
drywt)
Vacuum
10-50 kg/
m2/hr
(solids-
drywt)
Source: ADL, 1976
4.4.8.4 Design Basis
Contact time is primary design parameter (Adams and
Eckenfelder, 1974):
Granular Media Filters -- run time of filter system cycle
(initial to maximum allowable headless) is calculated as
follows:
T =
where:
t
ds/dt
694Q
A
T = time of filter run cycle
total filter deposit (lb/ft2)
rate of solids accumulation Ib/hr)
Q = design flow rate (mgd)
}a = hydraulic loading rate (gpm/ft2)
352
-------
• Rotary Drum Filters -- the filtration time to volume of fil-
trate is calculated as follows:
2 pA2 PA
where:
t/v = filtration time/filtrate volume (sec/ml)
y = filtrates viscosity (poise)
r = specific resistance (sec2/g)
c = solids removed per volume of filtrate (g/ml)
P = applied vacuum (g/cm2)
A = filtration area (cm2)
R = initial resistance of the filter media (sec2/cm2)
m
Filter Press -- design is based on quantity of filter cake
produced and the volume of sludge processed per unit time.
4.4.8.5 Principal Data Requirements
Granular Media
Leachate daily average flow (filter area)
Leachate suspended solids concentration (length of run)
Performance tests (laboratory)
• solids removal rate
• head loss
• bed expansion/backwash
Filter media characteristics (manufacturer's data)
Rotary Drum Filter
Leachate daily average flow (filter area)
353
-------
Leachate suspended solids concentration (filtration time,
area)
Fiiterability tests (laboratory-funnel tests)
• conditioner effects
• specific resistance
• cake constant
Filter loading tests (laboratory scale)
• compressibility coefficient
• solids concentration exponent
• form time exponent
Filter Press
Leachate daily average flow (filter area)
Leachate suspended solids concentration (filter area,
cycle time)
Fiiterability tests (laboratory scale)
• conditioner requirements
• cake resistance
• cake thickness
4.4.8.6 Elements of Cost Review
Components
Construction and Capital--
• filter
• pumps
354
-------
0 & M--
• electricity
• replacement of filter medium
Major Factors
• Surface area of filter medium
Data
A cost example (unit and total cost) is given in Table 4-34.
4.5 DIRECT TREATMENT
4.5.1 In Situ Leachate/Groundwater Treatment
4.5.1.1 Description
In situ leachate treatment introduces a reactant into the con-
taminated region to interact with the leachate plume. Two principal
variations are:
Permeable Treatment Beds -- This approach uses trenches
filled with a reactive permeable medium to act as an under-
ground reactor (see Figure 4-31). Contaminated groundwater
or leachate entering the bed reacts to produce a nonhazard-
ous soluble product or a solid precipitate.
Chemical Injection — This process entails injecting chemi-
cals into the ground beneath the waste (see Figure 4-32) to
neutralize, precipitate, or destroy the leachate constitu-
ents of concern.
4.5.1.2 Status
Permeable Treatment Beds -- Developmental,
Chemical Injection -- Conceptual.
355
-------
TABLE 4-34
VACUUM FILTRATION COST ESTIMATES AS A FUNCTION OF SIZE
(1982 dollars)
Treatment System Size
12,000 gpd
(2 tpd solids)
36,000 gpd 108,000 gpd
(6 tpd solids) (18 tpd solids)
Capital Investment
Variable Cost
Labor
Maintenance
Chemicals
Quicklime
Ferric Chloride
Electrical Energy
Total Variable Cost
$166,900
37,600
5,000
22
450
2,000
$ 45,100
$324,000
58,800
9,700
65
1,300
6,300
$ 76,200
$626,900
91,400
18,800
200
4,000
18,600
$133,000
Fixed Cost
Capital Recovery
Taxes and Insurance
Total Fixed Cost
Total Annual Cost
$ 27,200
3.300
$ 30,500
$ 75,600
Unit Cost (cost per
ton of dry solids processed) $107.08
$ 52,800
6.500
$ 59,300
$135,500
$ 62.37
$102,200
12.500
$114,700
$247,700
$38.72
Source: ADL, 1976
356
-------
FIGURE 4-31
INSTALLATION OF A PERMEABLE TREATMENT BED
(Source: EPA, 1982)
, Permeable Treatment Bed
357
-------
FIGURE 4-32
CROSS SECTION OF LANDFILL TREATED BY CHEMICAL INJECTION
(Source: EPA, 1982)
OJ
<_n
00
Metering pump
Well
pump
Wotarj
Table
30m
I tOOft)
27m
(90ft)
Water supply well
.Injection pipe is pulled
up and chemical is injected
at successive depths.'-
UNCONSOLIOATEO EARTH MATERIALS
-------
4.5.1.3 Feasibility and Effectiveness
general Eea-cures
Permeable treatment beds are applicable in relatively shallow
aquifers since a trench must be constructed down to the level of the
bedrock or an impermeable clay. Permeable treatment beds often are
effective only for a short time as they lose reactive capacity or
become plugged with solids. Over-design of the system or replace-
ment of the permeable medium can lengthen the time period over which
permeable treatment is effective.
The materials used for this form of treatment are:
• Limestone or crushed shell -- Limestone neutralizes acidic
groundwater and may remove heavy metals such as Cd, Fe, and
Cr. Dolomitic limestone (MgCC>3) is less effective at
removing heavy metals than calcium carbonate limestone.
The particle size of the limestone should match a mix of
gravel size and sand size. The larger sizes minimize set-
tling of the bed and channeling as the limestone dissolves.
The small sizes maximize contact. Extrapolated bench-scale
data indicate contact time needed to change 1 pH unit is 8
to 15 days.
• Activated carbon -- Activated carbon removes non-polar
organic contaminants such as CC14, PCBs, and benzene by
adsorption. Activated carbon must be wetted and sieved
prior to installation to ensure effective surface solution
contact.
• Glauconitic green sand -- This sand, actually a clay, is
found predominantly on the coastal plain of the Mid Atlan-
tic states and has a good capacity for adsorbing heavy
metals. Bench-scale studies indicate removal efficienc-
cies of greater than 90 percent for As, Cu, Hg, andNi, and
60-89 percent for Al, Cd, Ca, Cr Co, Fe, Mg, Mn and Zn, for
detention times on the order of several days.
• Zeolites and synthetic ion exchange resins -- These materi-
als are also effective in removing solubilized heavy
metals. Disadvantages such as short lifetime, high costs,
and regeneration difficulties make these materials econom-
ically unattractive for use in impermeable treatment beds.
• Chemical injection -- Sodium hypochlorite has been used to
treat leachate containing cyanide (Colman et al., 1978).
359
-------
Very little field data are available. The areal spread and
depth of the leachate plume must be well characterized so
that injection wells can be placed properly to intercept
all of the contaminated groundwater.
Special Precautions and Limitations
Permeable Treatment Beds
Plugging of the bed may divert contaminated groundwater and
channeling through the bed may occur. Both problems permit
passage of untreated wastes.
Changing hydraulic loads and/or contaminant levels may ren-
der the detention inadequate to achieve the design removal
level.
Injection
• Displacing pollutants to adjacent areas due to the added
volume of chemical solution.
• Producing hazardous compounds by reaction of injected chem-
ical solution with waste constituents other than the treat-
ment target.
4.5.1.4 Design Basis
A permeable treatment bed is constructed by digging a trench to an
impermeable layer (bedrock or clay), filling the trench with the
appropriate material and capping to control infiltration. The width
of the trench is determined by the permeabililty of the material
used for treatment, the groundwater flow velocity and the contact
time required for treatment. These parameters are related as:
= (vb)
-------
where:
w, = barrier width (m)
v, = groundwater flow velocity in the barrier
(m/sec)
t = contact time to achieve the desired
^»
removal (sec)
Groundwater velocity in turn is determined by Darcy's Law:
v = ks
where:
s = the gradient or loss of head per unit length
in the direction of flow (unitless)
k = coefficient of permeability, a soil-specific
value (m/sec)
Since the groundwater velocity through the permeable bed cannot
be predetermined, the trench should be designed for the maximum
groundwater velocity through the soil. If one assumes the hydraulic
gradient is equal for the soil and the permeable bed, the permeabil-
ity of the barrier must equal that of the soil.
4.5.1.5 Principal Data Requirements
Plume characteristics (bed design)
• depth to bedrock
• plume cross-section
• leachate or groundwater velocity
• hydraulic gradient
Soil permeability - laboratory test (bed design)
Leachate composition (reaction medium selection)
Reaction rate - laboratory test (contact time)
361
-------
4.5.1.6 Elements of Cost Review
Components
Construction and Capital--
Permeable Treatment Beds
• bed construction
• permeable medium
• monitoring instrumentation
Chemical Injection
• injection wells
• monitoring instrumentation
0 & M--
Permeable Treatment Beds
• medium regeneration and/or replacement
Chemical Injection
• chemicals
Major Factors
Permeable Treatment Beds
• size of bed
• type of permeable medium
Chemical Injection
• number of injection wells
362
-------
type of chemicals
Data
Cost for in situ leachate treatment are site specific. Unit costs
for potential "detoxification chemicals are given in Table 4-35. A
cost example for in situ detoxification is presented in Table 4-36.
4.5.2 In Situ Physical/Chemical Treatment
4.5.2.1 Description
In situ physical/chemical treatment involves the direct appli-
cation of a reactive material to a surface impoundment or to land-
filled waste to decontaminate the hazardous components. An example
of physical treatment is the addition of activated carbon to adsorb
organics. Chemical treatment involves neutralization, precipi-
tation and/or oxidation-reduction reactions; reagents can be found
in the appropriate leachate treatment section.
4.5.2.2 Status
Developmental. The basic physical/chemical methods to treat
waste have been developed and applied to segregated industrial waste
streams. In situ applications at uncontrolled sites have been lim-
ited.
4.5.2.3 Feasibility and Effectiveness
General Features
In situ physical/chemical treatment methods applicable to
homogenous concentrations of specific waste types include (EPA,
1982):
• oxidation of cyanide waste with sodium hypochlorite;
• reduction-of hexavalent chromium with ferrous sulfate;
• precipitation of heavy metals with alkali agents; and
363
-------
TABLE 4-35
COSTS OF POTENTIAL IN-SITU NEUTRALIZATION/
DETOXIFICATION CHEMICALS
Chemical 1982 Unit Costs
Calcium Chloride, 100 Ib bags $160/ton
Calcium Sulfate $36.20/ton
Potassium Permanganate $2.02/kg
Hydrogen Peroxide, 50% $0.28/lb
Sodium Hydroxide, liquid 50% $250/ton
Ferrous Sulfate $80/ton
Source: EPA, 1982
• adsorption of organics with activated carbon.
Special Precautions and Limitations
The waste to be treated should be physically isolated from waste
which is not compatible with the treatment reagent. Heterogeneous
wastes are not generally suitable for application of insitu treat-
ment methods. For example, application of a hypochlorite solution
to treat a cyanide waste constituent could chlorinate organic waste
constituents to produce other hazardous materials.
4.5.2.4 Design Basis
Performance characteristics will be specific at each site
application. An application of 15 percent hypochlorite solution to
a 24 cubic meter pit of cyanide contaminated soils (100 ppm cyanide)
yielded significant cyanide reductions based on groundwater moni-
toring data at the site (Kastman, 1977). Factors which affect engi-
neering performance are:
364
-------
TABLE 4-36
COSTS FOR IN-SITU DETOXIFICATION OF CYANIDE
Exploration probing, excavation, and drilling $20,700
Development of water supply well, 27 m (90 ft); 6,900
pump and piping
Installation of 45 well points 13,800
Cost of chemical feed pump 2,760
Cost of chemical (sodium hypochlorite) 6,900
Labor for chemical injection, raising of well 65,300
points to flood successive elevations
(assumed 4 wells handled simultaneously),
and general labor (1,600 hours)
Power (assumed electrical supply available) 640
$117,000
aAssumed 10-acre landfill with a total of 1,566 Ibs of cyanide distributed
within a fill volume of 4.9 million cubic feet. Chemical application rate
of 68 gallons per pound of cyanide.
Source: EPA, 1982
• the ability to mix the waste and the detoxifying agent,
i.e., stirrers for surface impoundments, cultivators for
landfill;
• the homogeneity of the waste mixture; and
• the availability of the waste constituents to react with
the detoxifying agent.
4.5.2.5 Principal Data Requirements
Site hydrogeology
Waste composition and distribution
Reaction rate (laboratory test)
365
-------
4.5.2.6 Elements of Cost Review
Components
Construction and Capital--
• excavation
• well or trench installation
• monitoring instrumentation
0 & M--
• chemicals
Major Factors
• type of chemicals
• area requiring treatment
Data
No information available.,
4.5.3 On-Site Physical/Chemical Treatment
4.5.3.1 Description
The description of on-site physical/chemical treatment tech-
nologies can be found in the discussion of individual leachate con-
trol technologies.
4.5.3.2 Feasibility and Effectiveness
Physical/chemical methods could be applicable to aqueous waste
366
-------
mixtures recovered on site. For example, the contaminated water of
a surface impoundment containing chlorinated cleaning solvents
could be neutralized. In general, any on-site liquid waste could be
considered amenable to physical/chemical leachate treatment methods
if the waste characteristics fall into the concentration ranges
applicable to leachate.
4.5.3.3 Elements of Cost Review
See sections on physical and chemical leachate treatment for
costs of various unit operations.
«f
4.5.4 In Situ Vitrification
4.5.4.1 Description
In situ vitrification is the melting of wastes and soil in place
to bind the waste in a glassy, solid matrix. In one process (Bat-
telle), wastes and soils are melted by passing an electric current
through the material between the electrodes.
4.5.4.2 Status
Developmental. Battelle Pacific Northwest Laboratories is
researching and developing an in situ vitrification process (Chemi-
cal Engineering, 1981).
4.5.4.3 Feasibility and Effectiveness
General Features
In situ vitrification has been sucessfully demonstrated in lab-
oratory and pilot scale tests with soils contaminated with radioac-
tive waste/soil mixtures. The process should be compatible with
non-volatile, inorganic waste/soil mixtures in general.
Special Precautions and Limitations
If volatile compounds are present, off-gases may be generated.
367
-------
4.5.4.4 Design Basis
• Power Consumption about 2000 kw/m3 (Brown, 1982)
• Melting temperatures about 1700 °C
4.5.4.5 Principal Data Requirements
Composition and extent of waste/soil mixture (implementa-
bility)
Treatability tests (laboratory and field tests)
4.5.4.6 Elements of Cost Review
Components
Construction and Capital--
• electrodes
• generator
• air pollution control equipment
• monitoring instrumentation
O & M—
• electricity
Major Factors
• Volume of wastes
368
-------
Data
No information available.
4.5.5 Solution Mining (Extraction)
4.5.5.1 Description
Solution mining (extraction) is the application of a solvent to
a waste solid or sludge, and collection of the elutriate at well
points for the removal and/or treatment of hazardous waste constitu-
ents. Typically, solvents used are water, acids (sulfuric, hydro-
chloric, nitric, phosphoric, carbonic), ammonia, and/or chelating
agents such as EDTA (ethylene diamine tetra-acetic acid) which solu-
bilize heavy metals and other inorganic ions. As the solvent is
collected, a fraction can be recycled through the landfill with a
make-up solution. The remainder can be .treated and disposed of.
4.5.5.2 Status
Conventional, undemonstrated; chemical extraction has been
used by the chemical processing and mining industries for many
years. The techniques are well understood, but experience with
in-situ treatment of hazardous waste is lacking. Bench-scale lab-
oratory studies of extraction of heavy metals from sludges and plans
to conduct full-scale metal extraction from industrial wastes have
been made.
4.5.5.3 Feasibility and Effectiveness
General Features
Very little data are available on the application of this tech-
nology in a remedial action setting.
Special Precautions and Limitations
The design and placement of injection and withdrawal wells must
prevent surrounding groundwater contamination with extracting sol-
vents and extracted material.
369
-------
4.5.5.4 Design Basis
• Selection of extraction solvent
• Well placement
• Injection location of extracting solvent
4.5.5.5 Principal Data Requirements
• Laboratory Testing
Extraction efficiency of various solvents for sol-
ution mining of waste. Waste analysis for presence
of constituents not compatible with solvent.
• Field Testing
Geohydrologic site survey to establish potential
for solvent migration into uncontaminated ground-
water and to establish well placement sites for
colleciton of elutriate.
4.5.5.6 Elements of Cost Review
Components
Construction and Capital--
• well construction
• monitoring instrumentation
• pumps
0 & M--
• chemicals
370
-------
Major Factors
volume or wastes
Data
Unit costs for eight potential extraction chemicals are given in
Table 4-37.
4.5.6 Biodegradation
4.5.6.1 Description
If wastes are biodegradable, in situ treatment of the waste
material using microorganisms may be a feasible treatment process.
Many naturally occurring bacteria break down chemicals via metabol-
ic activity (ingestion, respiration). Bacteria may be adapted from
naturally-occurring bacteria to break down specific constituents in
soil, and can be purchased in bulk quantity for that purpose. Most
biodegradation processes used to treat hazardous wastes are
aerobic; the technique usually used is to seed the waste material in
situ with microorganisms or transport and spread the waste on aerat-
ed soils (land treatment) . Surface impoundments in.which the wastes
may be mechanically aerated are also candidates for using in situ
biodegradation.
4.5.6.2 Status
• Land treatment -- conventional, demonstrated at controlled
sites, but application to remedial action at uncontrolled
sites is uncertain.
• In situ biological seeding -- developmental.
4.5.6.3 Feasibility and Effectiveness
General Features
For in situ biological seeding, continuous seeding may be
371
-------
TABLE 4-37
UNIT COSTS FOR EXTRACTION CHEMICALS
Chemical 1982 Unit Cost
Hydrochloric Acid, 20% acid $ 85/ton
Nitric Acid, up to 42 Be 175/ton
Sulfuric Acid, Virgin 52.10-83.80/ton
Sulfuric Acid, Smelter 6-52.10/ton
Caustic Soda, Liquid 50% 250./ton
Citric Acid 0.04/lb
Sodium Lauryl Sulfate, 30% 0.22/lb
Source: EPA, 1982
required where there are other microbial predators, excessive wash-
out, and/or other adverse environmental conditions such as presence
of toxic metals.
Biodegradation has been used most widely for treatment of oily
sludges and refinery waste. Bacteria developed for biological seed-
ing are capable of degrading:
• benzenes
• phenols
• cresols
• naphthalenes
• gasolines
• kerosenes
• cyanides
372
-------
Special Precautions and Limitations
In land treatment, if soils are not well aerated, waste degrada-
tion will not occur. Because metals are not degraded earful atten-
tion should be given to the toxic metal load at the site.
4.5.6.4 Design Basis
Key factors for biodegradation include:
• nutrient balance
• pH maintenance
• soil aeration
• degradation rate of wastes constituents
For detailed information on the design and management of land
treatment facilities, see TRD 8.
4.5.6.5 Principal Data Requirements
Type, quantity, and distribution of waste constituents
(seed, nutrient, air requirements)
site typography and hydrogeology (injection, withdrawal
system design)
soil-physical, chemical, and biological properties (seed
and nutrient requirements)
4.5.6.6 Elements of Cost Review
Components
Construction and Capital--
373
-------
• spreading wastes
• aeration
0 & M--
• analysis
• soil cultivation
Major Factors
Volume of waste
Data
Total biannual cost for in situ biological degradation of
wastes on a one acre plot is $11,200 (1982 dollars) .
4.5.7 Solidification/Stabilization
4.5.7.1 Description
Solidification/stabilization technologies (referred to as sol-
idification technologies in this section) reduce leachate pro-
duction potential by binding waste in a solid matrix by a physical
and/or chemical process. Wastes are mixed with a binding agent and
subsequently cured to a solid form.
4.5.7.2 Status
Cementation (including pozzolanic.) -- conventional, demon-
strated. Other processes -- developmental.
4.5.7.3 Feasibility and Effectiveness
374
-------
General Features
uour approaches, identified in the literature, are:
• Cementation: Used to treat inorganic waste streams with
Portland cement. This solidification technology is the
least sensitive to waste variability.
• Pozzolanic cementation: Treats inorganic waste streams
using what is often another solid waste (fly ash or cement
kiln dust) . The solidified product is more porous than the
one using Portland cement.
• Thermoplastic binding: Treats wastes with binders such as
bitumen, paraffin and polyethylene. These materials have
been used on radioactive wastes, for which the technology
was developed.
• Organic polymer binding: Treats wastes with polymer form-
ing organic chemicals, such as urea and formaldehyde. This
option was also developed as a disposal method for radioac-
tive wastes. One organic polymer used is
urea-formaldehyde.
Solidification technologies have been most successful when
applied to inorganic waste streams. Wastes compos'ed of 10-20 per-
cent organic content are generally not amenable to solidification
technologies (EPA, 1980). Exceptions are noted in the literature.
For example, an oily sludge which was stabilized in a lime-treatment
pro-cess (Soil Recovery, Inc., Morristown, NJ) .
Abandoned sites with large volumes of contaminated soils, inor-
ganic sludges, solids and/or concentrated inorganic aqueous wastes
are prime candidates for application of solidification methods. To
improve the homogeneity and suitability of wastes for solidifica-
tion, waste could be blended with contaminated soil. The solidified
product would be in a form suitable for on-site landfill or basic
construction.
Special Precautions and Limitations
Treatable waste forms and waste classes that interfere with
solidification are summarized in Table 4-38.
375
-------
TABLE 4-38
SUMMARY OF TREATABLE WASTE FORMS AND INTERFERING WASTE CLASSES
Solidification Technology
Treatable Waste Interfering Waste
Forms Classes
Cementation (including Pozzolanic)
Thermoplastic binding
Organic polymer binding
Waste slurries
Dried waste
Sulfate, Borates
Nitrates, Chlorates,
Perchlorates,
Organic Solvents
Dewatered waste Toxic metal salts
Source: TRD 6
Research is being conducted on long-term considerations such as
product stability over the course of several freeze/thaw cycles.
4.5.7.4 Design Basis
Key design factors are:
• solidification mixing ratios;
• curing time; and
• volume increase of solidified product.
The evaluation of these factors is dependent on the solidifica-
tion technology and the specific waste being treated.
4.5.7.5 Principal Data Requirements
Waste characteristics (binding agent selection):
pH
• buffer capacity
376
-------
• water content
• total organic carbon (TOC)
• inorganic and organic constituents
Treatability tests (cure time, mix):
• leachability
• strength
4.5.7.6 Elements of Cost Review
Components
Construction and Capital--
• tanks
• pumps
• mixers
O & M--
• chemicals
• analysis
Major Factors
• solidification option used
• volume of waste
• pretreatment requirements
377
-------
Data
A cost example (unit and total costs) is presented in Table 4-39.
4.5.8 Incineration
4.5.8.1 Description
Incineration combusts or oxidizes organic material at very high
temperatures. The end products of complete incineration are CC>2
H20, S02, NOX , and HCL gases. Emission control equipment
(scrubbers, electrostatic precipitators) for particulates, SO2, NOX
and products of incomplete oxidation are needed to control emissions
of regulated air pollutants.
Common types of incinerators most applicable to hazardous waste
include:
• rotary kilns,
• multiple hearth,
• f luidized bed, and
• liquid injection.
4.5.8.2 Status
Conventional, demonstrated.
4.5.8.3 Feasibility and Effectiveness
General Features
The key features of incineration methods cited previously are
summarized in Table 4-40.
378
-------
TABLE 4-39
COSTS OF CHEMICAL FIXATION FOR A DISPOSAL SITE
(1982 dollars)
Basis: - Stabilized waste materials are not releasing toxic levels of
pollutants.
- Cost of obtaining fixation agents (e.g., fly ash) is free.
- Only top %m of landfill is mixed with fixation agents.
Total Unit $
Capital Costs
Excavating and Grading, Waste
(27,685 m3)
Excavation and Grading, Soil
(16,910 m3)
Application of Stabilized Waste
Material (33,218 m3)
Capital Cost (subtotal)
Overhead Allowance (25 percent)
Contingency Allowance (35 percent)
Total Capital Cost
Lower U.S.
42,310
18,380
221,820
282,510
70,630
98.880
452,020
Upper U.S.
50,750
21,440
461,250
533,440
133,360
186.700
853,500
O&M Costs
Monitoring
Sample Collection 12 days/yr
(96 hr/yr) 890
Analysis 9,220
- Primary & Secondary Parameters
- 12 background/yr
- 12 downgradient/yr
24 samples/yr
Total O&M Costs 10,110
Average Capital Cost/m3 stabilized waste $13.60
o
Average O&M Cost/m stabilized waste g 0.30
1,820
9,220
11,040
$25.70
$ 0.33
Source: SCS, 1981
379
-------
TABLE 4-40
KEY FEATURES OF MAJOR TYPES OF INCINERATORS
Type
Process principle
Application
Combustion temp.
Residence time
U)
00
o
Rotary Slowly rotating cylinder
kiln mounted at slight incline
to horizontal. Tumbling
action improves efficiency
of combustion.
Multiple Solid feed slowly moves
hearth through vertically stacked
hearths; gases and liquids
fed through side ports and
nozzles.
Liquid Vertical or horizontal
injection vessels; wastes atomized
through nozzles to increase
rate of vaporization.
Fluidized Wastes are injected into a
bed hot agitated bed of inert
granular particles; heat
is transferred between the
bed material and the waste
during combustion.
Most organic wastes;
well suited for
solids and sludges;
liquids and gases.
Most organic wastes,
largely in sewage
sludge; well suited
for solids and
sludges; also handles
liquids and gases.
Limited to pumpable
liquids and slurries
(750 SSU or less for
proper atomization).
Most organic wastes;
ideal for liquids,
also handles solids
and gases.
810-1,640°C
(1,500-3,000°F)
760-980°C
(1,400-1,800°F)
Several seconds
to several hours
650-1,650°C
(1,200-3,000°F)
750-870°C
(1,400-1,600°F)
Up to several
hours
0.1 to 1 second
Seconds for gases
and liquids;
longer for solids
Source: Ghassemi, et al., 1981
-------
Special Precautions and Limitations
If an incineration system is not working properly, incomplete
combustion products that may be toxic can be emitted to the atmos-
phere. If halogenated materials are present, then air pollution
control will be necessary to prevent the emissions of inorganic
acids to the atmosphere.
Residual ash is typically inorganic. Since it probably con-
tains a high concentration of metals, it should be handled as a haz-
ardous waste.
4.5.8.4 Design Basis (Ghassemi et al., 1981)
• Afterburner temperature of 1200 degrees C (2012 degrees F)
required by Federal regulations.
• Two second dwell time in afterburner required by Federal
regulations.
• Three percent excess oxygen required by Federal
regulations.
• A scrubber to remove SC>2 and HCL from gas emissions if nec-
essary.
4.5.8.5 Principal Data Requirements
Waste constituents and characteristics (suitability)
• moisture content
• volatile materials content
• ash content
• ash specific level, specific gravity or bulk den-
sity
• ash particle size range
• carbon hydrogen, oxygen, halide, sulfur, nitrogen,
phosporus content
381
-------
• waste specific gravity, viscosity, and melting
point
• metal content
• thermogravimetric analysis
• suspended and dissolved solids
• reactive chemical groups
• flammability, stability, detonation
• environmental sensitivity
• toxicity
Process characterization (pilot test):
• residence time
• temperature
• destruction efficiences
• ash residue
• gaseous effluent
4.5.8.6 Elements of Cost Review
Components
Construction and Capital--
incineration unit
pollution control equipment
0 & M--
fuel
monitoring
382
-------
• maintenance
• ash disposal
Major Factors
Process size
Data
Unit cost for rotary kiln incineration and multiple hearth
incineration are given in Table 4-41.
4.5.9 Thermal Oxidation Systems
4.5.9.1 Description
Thermal oxidation destroys hazardous components in a gas by
combustion. The major combustion products are carbon dioxide and
water.
4.5.9.2 Status
Conventional, demonstrated.
4.5.9.3 Feasibility and Effectiveness
General Features
Two principal types of oxidation systems are:
• Flaring -- A flare consists of an ignition chamber in which
an ignitable gas is allowed to combust in a controlled air
environment. A pilot burner is used to ignite the vent gas-
es. Steam is added to smokeless flares to convert any
unburned heavy hydrocarbons to carbon dioxide and hydrogen
(EPA, 1982). Usually, smokeless flares are not required
for treating vent gases in waste disposal sites since the
383
-------
TABLE 4-41
UNIT COSTS OF WASTE DISPOSAL BY INCINERATION
(1982 dollars)
Assumption Cost
Rotary kiln Installed cost $50-200 /lb/hr
incineration
Annual maintenance 5%-10% of
cost installed cost
Multiple hearth Dry solids (sludge
incineration 15% moisture)
Installed cost $42-3/4/lb/hr
Operating cost $3-38/ton
Multiple chamber Installed cost $14-29/lb/hr
incineration
Operating cost
(includes capital cost) $26-27/ton
Source: EPA, 1982 , Draft Report (6/80)
gases do not normally contain any hydrocarbons that gener-
ate smoke during combustion.
• Afterburners -- Afterburners are incinerators for gases and
vapors. Additional fuel is added to the waste gas stream to
generate a high temperature after combustion. Incoming gas
and vapors passing through the afterburner decompose at the
high temperatures in the presence of oxygen, producing car-
bon dioxide, water and other combustion products. In some
cases afterburners incorporate a catalyst to facilitate
oxidation at lower temperatures.
Special Precautions and Limitations
Use of flares and/or afterburners should be generally
restricted to tho.se pollutants which will not produce undesirable
oxidation products such as fluorides.
384
-------
The changes in air flow rate and composition can interfere with
thermal oxidation systems. The extreme conditions and condition
variability should be considered when designing the system.
4.5.9.4 Design Basis
Flares
• Gas and/or vapors must be flammable. Heating value of gas
or vapors should be greater than 100 BTU/ ft3 (Lund, 1971) .
• Flow rate of gas and vapors is a key design factor.
Afterburners
• Should be employed only to treat gases that can be oxidized
at temperatures of 870 degrees C or less with a retention
time of about 0.5-1.0 seconds.
• In cases where the gas is relatively unstable, a catalytic
afterburner may be used to lower oxidation temperatures
(540-870 degrees C) .
4.5.9.5 Principal Data Requirements
Gas and vapor volume vented (average and extremes)(system
capacity)
Concentration of contaminants in gas (implementability,
capacity)
Destruction efficiencies (bench or pilot tests)
4.5.9.6 Elements of Cost Review
Components
Construction and Capital--
flare burners
385
-------
• afterburners
• vent installation
0 & M~
• fuel
Major Factors
• capacity of burner
• fuel requirements
Data
Installed costs for a flare system range from $2,250 to $4,500,
1982 dollars, for 20 to 670 cubic feet per minute gas flow (EPA,
1982).
Installed costs for afterburner systems range from $9 to $37
(1982 dollars) and annual operating costs range from $12 to $48
(1982 dollars) (EPA, 1982).
4.5.10 Carbon Adsorption For Air Emissions
4.5.10.1 Description
Carbon adsorption systems consist of a tank, drum, or other con-
tainer that supports a bed of activated carbon. Contaminated gas
flowing through the carbon bed is adsorbed on the carbon surface due
to Van der Waals attraction and chemical bonding. The adsorbed gas-
es can then be removed from the carbon by raising the temperature,
often by use of steam. This regeneration process may be carried out
on site, or the carbon can be removed and taken to an off-site regen-
erator.
4.5.10.2 Status
Conventional, demonstrated.
386
-------
4.5.10.3 Feasibility and Effectiveness
General Features
In cases where small gas volumes and/or gas with low organic
concentrations are being treated, it is generally cheaper to replace
rather than regenerate the spent carbon. If very toxic chemicals
such as dioxins are present, it may be best to use a non-regenerative
system and dispose of the spent carbon since regenerated carbon has
lower removal efficiencies. When treating large volume gas streams,
regenerative systems are generally the more economic choice.
Retentivity is dependent on the type of substance being
adsorbed, so operating times are expected to be different for vari-
ous chemicals, all other factors being constant. Table 4-42 lists
several organic compounds with their retentivity before and after
regeneration.
Special Precautions and Limitations
The air emissions from carbon adsorption units should be moni-
tored to insure the unit is functioning properly.
4.5.10.4 Design Basis
The maximum time period that a carbon bed can operate without a
loss of efficiency, i.e., before the carbon must be replaced or
regenerated, may be calculated by using the following equation (EPA,
1982):
SW
max MQCv/RT
where:
t = maximum time of affective use, sec
S = fractional retentivity of adsorbent, mass
adsorbate/mass adsorbent
387
-------
TABLE 4-42
RETENTIVITY FACTORS OF ORGANIC COMPOUNDS
Approximate Retentivity
. Retentivity After
Adsorbate Weight Fraction5 Regeneration^
Benzene
Carbon Tetrachloride
Gasoline
Methyl Alcohol
Isopropyl Alcohol
Ethyl acetate
Acetone
Acetic acid
o
0.25
0.45
0.07
—
0.18
0.20
0.10
0.30
0.06
0.20
0.02
0.01
0.01
0.05
0.03
0.03
stream at 20°C.
Regeneration with steam at 150° C for 1 hour.
Source: EPA, 1982
W = mass of adsorbent in the bed, Kg
M = molecular weight of adsorbate, kg/mol
Q = volumetric flowrate of total gas, I/sec
R = gas constant, .082 1-atm/mol K
T = temperature, K
C = volume fraction of vapor in total gas
4.5.10.5 Principal Data Requirements
Type and concentration of contaminant in the waste gas sys-
388
-------
tern (carbon usage)
The total amount of vented gas (volume, carbon usage)
Carbon adsorption efficiency (laboratory tests)
4.5.10.6 Elements of Cost Review
Components
Construction and Capital--
• pumps
• carbon
• monitoring instrumentation
0 & M--
• carbon replacement
Major Factors
• air volume
• pollutant concentration
Data
A cost example is shown in Figure 4-33.
389
-------
FIGURE 4-33
CAPITAL AND OPERATING COSTS FOR NON-REGENERATIVE CARBON
ADSORPTION SYSTEMS TREATING VENT GAS CONTAINING 50 PPM
TRICHLOROETHYLENE
(Source: EPA, 1982)
100-
90-
80-
70-
60-
50H
40-
30-
P 20-
10-
"o
Q
w
•a
c
CD
CO
O
w
8
Total
Installed
Annual
Operating
0
2345678
Flow Rate (Thousand Cubic Feet Per Minute)
rIOOO
-900
-800
-700
-600
-500
-400
-300
-200
-100
3
Q)
(Q
O
O
I
Q.
V)
D
O,
5T
10
a. To update total installed costs to 1982 $, multiply by 1.12.
b. To update annual operating costs to 1982 $, multiply by 1.59.
390
-------
SECTION 5
MONITORING TECHNIQUES
The principal objectives of monitoring systems at abandoned
waste sites generally change over the life of a specific project.
These objectives, in more or less chronological order, are:
• determination of exposure and contamination effects on
humans, sensitive and important nonhuman species, and the
environment.
• site assessment pursuant to design of a remedial action
program.
• evaluation of the effectiveness of the remedial action pro-
gram.
Any monitoring program must be designed with a clear focus on
meeting one or more of these objectives. Failure to define objec-
tives will generally result in less than optimal use of monitoring
funds.
There are essentially two types of information that a monitor-
ing program may be expected to provide:
• the setting (geologic, hydrologic, topographic, etc.) of
the site, and
• the contamination distribution (type and concentration) at
the site.
This information should elucidate the nature of the problem in
the principal environmental media involved. These media, using the
same categories as-in Chapter 2, are:
391
-------
• groundwater
• surface water
• soil
• air
Data on biota may also be required.
The major issues to be addressed in designing and conducting a
monitoring program are:
• what methods to use;
• where (location) and when (frequency) information/samples
will be collected;
• and how to analyze the samples.
The discussion below emphasizes the choice and location issues.
Questions of frequency and laboratory analysis of samples taken at
the site are only briefly examined.
Monitoring program design will vary depending on the objectives
as indicated in Table 5-1. A monitoring program designed for site
assessment prior to design of a remedial action program must lead to
a characterization of the setting of the site as well as the levels
and pattern of site-related contamination. The location of soil
borings, monitoring wells, air samplers, etc. must provide a fairly
detailed characterization of the physical environmental setting of
the site (e.g., the characterization of subsurface soil profiles).
A monitoring program designed to evaluate the effectiveness of
a remedial action would not normally require additional monitoring
to characterize geology, but may demand "before and after" water or
air flow characterization as well as contamination monitoring. The
siting of monitoring devices will be focussed on the action (e.g.,
immediately downgradient of a cutoff wall, or immediately above a
landfill "cap").
When monitoring is designed to assess exposure to human or non-
human receptors, only contamination levels need to be monitored.
Sampling locations siting should reflect locations of intensive use
392
-------
TABLE 5-1
MONITORING PROGRAM DESIGN CONSIDERATIONS.
Objective
Exposure /Health
Effects
Site Assessment
Evaluate Effect of
Remedial Action
Environmental
Geology /Topography
X
Setting
Flow (air or
water)
X
X
Contamination
X
X
X
Where
When
Where
When
Where
When
Comments
Consider all media;
location is area of
intensive use by human
or sensitive and im-
portant non-human
species.
Dependent on exposure/
health effect scenario.
Consider all media;
location determined en-
tirely by site setting
characteristics.
Depending on urgency,
perhaps only one sample
will be taken at each
sampling location.
Consider all media;
locate so as to observe
earliest effect (prob-
ably close to site of
Remedial Action.)
Dependent on nature of
Remedial Action.
u>
\O
u>
-------
for the target organism (e.g., a marsh, bathing beach, or domestic
well).
The remainder of this section consists of a discussion of gener-
al guidelines for designing monitoring programs (what, where, when)
in order to meet the objective, followed by a brief summary of tech-
nologies and procedures for monitoring the setting of disposal sites
and related contamination levels. In addition, monitoring wells are
discussed in detail at the end of the section in the format of the
technology discussions in Sections 3 and 4.
5.1 MONITORING PROGRAM GUIDELINES FOR REMEDIAL ACTION ASSESSMENT
The focus of this document' and the following discussion is on
the second of the three objectives listed above. Site assessment
pursuant to design of a remedial program requires a comprehensive
monitoring program in contrast to programs that might be developed
to meet the other two objectives. Site assessment monitoring is
intended to:
• define the setting in the soil phase (geology/topography)
and in the air and water.
• determine the site-related contaminant distribution.
• determine rates of contaminant migration from the site.
To accomplish these objectives, decisions as to when, where,
and what to monitor should be made based on the answers to the fol-
lowing questions:
• Where was the waste disposed?
• When was the waste disposed?
• What wastes are likely to be found at the site?
• What are likely to be important pathways for contaminant
migration (air, surface runoff, groundwater)?
• In what direction would contamination likely migrate by
each important pathway?
• How rapidly would it be likely to migrate?
394
-------
• Given the period since the waste was disposed, how far is it
likely to have traveled?
• Are there other sources of contamination in the vicinity?
• Are there other man-induced phenomena which may now, or
during the site's lifetime, affect contaminant migration
(for example, a major production well)?
The following approaches, by themselves, will not, in general, con-
tribute to the remedial action plan assessment objective:
• sampling near property or political boundaries
• sampling on a predefined grid without regard to geologic or
topographic consideration
• sampling a domestic well (unless it is fortuitously sited
in a region of probable impact)
• sampling near a distant residential area
• sampling and analysis designed to monitor a predetermined
list of contaminants (i.e., drinking water standards) with-
out regard to wastes disposed at the site.
From archived information and a visual inspection of the site,
possibly augmented by remote sensing procedures such as an elec-
trical resistivity survey, a qualified hydrogeologist should be
able to hypothesize in broad outline the direction of surface and
shallow groundwater flow from the site as well as rough estimates of
hydraulic gradient and permeability of the soils. This kind of pro-
cedure can generally give only an order of magnitude estimate at
best. Applying Darcy's Law using the estimated characteristics, the
downgradient extent of contaminated groundwater can be
approximated. This estimation technique is general and is useful
only in planning the monitoring program -- not for hazard
assessment.
The results, however, may be extremely useful if they indicate
that the contaminant should not have migrated far from the original
waste location. In this case, monitoring wells need be sited only
near the site with several downgradient and one or more upgradient.
The number of monitoring wells to use is site-specific, depending
not only on the complexity of the site, but to some extent on the
perceived degree of hazard.
395
-------
If there is evidence of significant downgradient contaminant
migration, a more extensive pattern of monitoring wells may be
recommended -- perhaps an inner semi-circle near the site to define
the rate and quality of leachate migration, and outer rings or lines
of wells downgradient to establish the full extent of contamination,
as shown in Figure 5-1. The well pattern shown is designed to deter-
mine the extent of contamination.
The above techniques for defining the contamination is not nec-
essarily the best way to define the flow regime. Definition of the
flow regime may require additional piezometers and/or soil borings.
5.2 MONITORING FOR REMEDIAL ACTION EFFECTIVENESS
To evaluate the effectiveness of a remedial action program,
monitoring needs will be defined from the type and location of the
remedial actions. Monitoring systems should be designed to detect
the effect of the remedial action as soon as possible after its con-
struction. This need is usually met by two design criteria:
• measure the quantity/parameter directly affected by the
action
• measure that quantity as close to the site of the action as
practicable.
For example, if a capping program is designed to reduce volatile
air emissions of organics, an air sampler should be situated near
the ground over the capped area. Before and after sampling would
normally be advisable.
As another example, if an extraction well were designed to lower
the water table, one should install piezometers in the expected zone
of influence. Taking groundwater samples for analysis may not be
required to evaluate such a system. If, on the other hand, the
intent of an extraction well is to reverse and collect the flow of a
contaminated groundwater plume, monitoring wells should be
installed near the leading edge of the plume.
Finally, in monitoring for health effects and toxic exposure,
the best technique may be tissue samples from exposed people or oth-
er target species. Sampling of domestic wells in an area of possible
contamination may be appropriate, as well as sampling air quality in
a nearby residential area.
396
-------
FIGURE 5-1
PLACEMENT OF MONITORING WELLS
Estimated Extent
of Contamination
o/
\
b o
o"-9—
Legend:
O Monitoring Wells
A Piezometers
0 Background Wells
I
I
Waste
Direction of Flow
Background Well
5.3 MONITORING AND SAMPLING TECHNIQUES
5.3.1 Monitoring and Procedures to Determine the Setting
The setting consists of:
land characteristic — geology, topography
air and water characteristics -- winds, surface water lev-
els and currents, groundwater heads and flow rates
397
-------
At most sites a considerable base of information on the setting
is available in existing data archives maintained by the United
States Geological Survey (USGS), National Climatic Center of the
National Oceanic and Atmospheric Administration (NOAA/NCC), U.S.
Army Corps of Engineers, U.S. EPA, and state and local agencies. The
available data may obviate the need for extensive data gathering.
Usually, however, data from the conventional sources listed below
are not locally detailed and sufficiently site-specific to support
design of a remedial action plan. The most important
readily-available data and their sources are:
• surface weather observations (NOAA/NCC)
• surface topography (USGS)
• surface water levels and discharge rates (USGS, U.S. Army
Corps of Engineers, U.S. EPA, state and local water surveys
and local water supply agencies)
• subsurface geology (USGS, state and local geological survey
agencies)
• groundwater levels, yields, and discharge rates (USGS,
state and local geological agencies)
The data sources above must generally be supplemented in
site-specific assessment of waste sites in the following
categories:
• surface water levels and discharge rates of minor streams
are not generally available in archives -- techniques
include staff gages (calibrated sticks or rules used to
measure water level) and weirs;
• localized subsurface geology must be determined via soil
borings and/or in situ well logging; and
• localized groundwater conditions must be determined via
wells and/or piezometers.
Several well logging and in situ techniques may be useful in
assessing local subsurface geology and subsurface moisture. Neu-
tron moderation and gamma-ray attenuation are examples of two in
situ techniques for determining moisture content. They are princi-
pally useful air the unsaturated zone, do not require sample col-
lection, and provide "real-time" data useful in deciding where to
collect a sample, screen a well, install a lysimeter, and so on.
398
-------
Geophysical well logging provides indirect evidence of subsur-
face formation and relative permeabilities. Natural gamma radi-
ation frpm subsurface materials indicates the presence of clay or
shale. Electric resistivity logging records the apparent resistiv-
ity of subsurface formations, which will vary with particle size and
the conductivity of the occluded water. Leachate is usually iden-
tifiable by its high conductivity, relative to natural, non-saline
groundwater. These two procedures should generally be used in con-
junction with each other in order to obtain a meaningful
interpretation of the results. Figure 5-2 shows how a leachate
plume may be detected via these techniques (Fenn et al. , 1977) .
5.3.2 Monitoring Procedures for Assessment of Site-Related
Contamination
Most monitoring procedures described here are, essentially,
sampling procedures. Standard procedures for analyzing water or
other environmental samples are not addressed in detail. However,
there is an important group of in situ tests which can determine con-
taminant distribution without collecting a sample, some of that can
provide "real-time" diagnosis. The discussion of contamination
assessment procedures is organized into the following categories:
saturated groundwater, unsaturated soil zone, surface water, soil,
biota, air, and remote sensing.
5.3.2.1 Saturated Groundwater Zone
Groundwater from the saturated zone must generally be obtained
from wells, though sampling of springs and leachate seeps may pro-
vide a fortuitous and inexpensive indicator of groundwater quality
at some sites. Important considerations in developing wells for
sampling groundwater near hazardous waste sites for subsequent
analysis are:
• proper sealing to prevent the well itself from contributing
to vertical migration of contaminants;
• special casing materials to prevent inadvertent sample con-
tamination: PVC pipe is good for subsequent metals analy-
sis while galvanized steel is good for subsequent organic
analysis; other contaminant resistant materials include
TeflonRr fiberglass-reinforced epoxy pipes, stainless
steel, and rubber-modified polystyrene (Everett, 1976);
PVC wrth_screwed (not glued) connections may also be used
for some organic sampling.
399
-------
FIGURE 5-2
DETECTION OF A LEACHATE PLUME USING AN ELECTRIC WELL LOG
(Source: Fenn, et al., 1977)
-P-
o
o
GAMMA
LOG
ELECTRIC
LOG
( RESISTIVITY)
••C#3/
too
125
ISO
ITS
EOC
r
i
DRILLERS
LOG
••:SANO ••;'-.
-CLAY-
O «OCK,
-gamma log is included because it indicates
that the leachate plume is not actually a clay
layer.
-------
• drilling techniques and use of drilling muds which can
affect in situ permeability tests and cause contamination
of samples;
• well screen length and depth must be carefully selected to
sample specific strata of the aquifer;
• sturdy well covers and anchoring with grout and/or cement
to prevent contamination from the surface and discourage
vandalism or inadvertent damage from other activities at
the site; and
• procedures for protecting drilling teams and the general
public if it is expected that toxic gases may be released
during drilling.
Samples of groundwater are generally taken during well
drilling. These samples may be very useful in deciding the appro-
priate screen depth to sample the most contaminated layer of the
aquifer. Soil samples, commonly taken via split spoon or Shelby
tube samplers, may be examined for qualitative evidence of contam-
ination (with care to avoid toxic exposure).
Water sampling techniques during drilling include:
• drilling a casing or well point to a desired depth, bailing
or pumping a sample and repeating the process to the com-
pletion depth;
• drilling a mud rotary boring, constructing a temporary well
screen and packing, and pumping a formation water sample;
and
• drilling a borehole to a desired depth, setting a packer
pump and riser pipe and pumping a sample.
Procedures for obtaining soil samples during drilling are
briefly discussed below. Soil pore water may be extracted from
soils by filter press or centrifuge for subsequent analysis. Such
procedures find greatest applicability in the unsaturated zone
where it is more difficult to obtain a water sample.
5.3.2.2 Groundwater in the Unsaturated Zone
Lysimeters are the most common sampling devices for obtaining
401
-------
water from the unsaturated zone. Squeezing pore water from soil
samples is the only practical alternative. Lysimeter designs
include:
• vacuum
• trench
Vacuum lysimeters draw water through a porous ceramic cup
emplaced in the soil, while trench lysimeters passively intercept
percolating water. Thus, trench lysimeters are only effective when
and where substantial percolation occurs, for example:
• under a hazardous waste lagoon, and
• immediately during and after rainstorms on a landfill.
Vacuum lysimeters are expected to find more general applicabil-
ity at hazardous waste sites. However, pumping with vacuum is not
generally used when volatile organics are suspected, as the vacuum
pulls the volatiles out of solution.
5.3.2.3 Surface Water
Surface water sampling is a mature and relatively simple tech-
nology with well-standardized methods. Surface runoff collection
may require small structures such as weirs to collect an adequate
sample volume for analysis. Runoff may be collected also via soil
plugs (screened cups which are driven into the soil so as not to
alter the runoff flow).
5.3.2.4 Soil
Soil samples may be obtained from the saturated or unsaturated
zone or as surface water-body bottom sediment. The solid phase may
be extracted with chemical solvents to identify contamination
adsorbed on or precipitated with the soil. Although extraction of
soils may be performed on saturated soils, such procedures find
greatest applicability in the unsaturated zone where it is more dif-
ficult to obtain a water sample. The technique has several
disadvantages including:
402
-------
• few labs are equipped for such analysis;
• there is no standard method;
• precise quantitative analysis of sorbed organics has not
been adequately demonstrated to date; and
• analytical costs are higher than a simple water sample.
However, the technique does permit pinpointing of contaminated
zones to a degree of spatial resolution not possible with well samp-
ling where water is drawn from relatively larger volumes.
Extraction may be the only feasible method for contamination assess-
ment in unsaturated soils with low moisture content.
Remote sensing monitoring is used to provide a reasonably accu-
rate assessment of subsurface contamination including the location
and extent of buried wastes. The types of remote sensing techniques
include:
Electrical Resistivity
• Resistivity is used to define a leachate plume
based on the fact that leachate is more conductive
than uncontaminated groundwater.
• Lateral profiling can be used to determine the are-
al extent of contamination and can assist in the
placement of monitoring wells.
• Depth profiling indicates the change in contam-
ination with depth and defines complex stratigra-
phy.
Ground Penetrating Radar
• Used to locate buried objects and to provide qual-
itative information about drum density, to detect
interfaces between disturbed and undisturbed soil,
and to detect leachate plumes.
• Based on the principle that electromagnetic
pulses, reflected from subsurface interfaces or
objects, are detected by antennae held at the
ground.
Seismic Refraction
403
-------
used to locate interface between subsurface depos-
its and determine the nature of each deposit
based on the principle that induced compression
waves reflect at interfaces and refract depending
on the properties of the new medium of propagation.
Fisher M-Scope and Proton Magnetometer -- used to detect buried
metal objects.
5.3.2.5 Biota
Sampling and analysis of biota may, in some circumstances, pro-
vide an early indication of environmental quality deterioration for
bioaccumulated contaminants whose concentration in ambient air or
water is below detection limits. Another promising mode of investi-
gation is the potential for visual assessment of vegetation stressed
by contaminants. There are many advantages to bio-monitoring:
• provides the first indication of contaminant migration;
• can be used to locate contaminant plumes for direct samp-
ling; and
• can be accomplished in a few hours on site by a trained
ecologist.
However, the lack of visual stress does not necessarily imply a
lack of contamination so the method is not foolproof.
5.3.2.6 Air Monitoring
Two types of air emissions can occur at waste sites, vaporiza-
tion of volatile organic compounds and entrainment of particulate
matter. Each type requires different monitoring procedures to meas-
ure the impacts. The following describes the steps to be taken to
monitor the air quality impacts from a waste site.
Vaporization of Organic Compounds
• Collect vapors directly above or downwind of the site in
404
-------
sorbent traps or low temperature traps;
• Analyze the trapped vapors in laboratory gas chromatographs
and mass spectrometers; and
• Relate concentrations to the ambient conditions by record-
ing flow rates through the traps.
Entrainment of Particulate Matter
• Collect samples directly above or downwind of the site in
hi-vol filter devices for approximately a 24-hour period;
• Weigh the filters to determine total suspended matter col-
lected;
• Analyze the filters by optical and electron microscopy and
by X-ray fluorescence to identify species collected; and
* Relate collected mass of each species to ambient concen-
trations by considering air flow rates through the filter.
5.3.3 Monitoring Wells
5.3.3.1 Description
There are four major types of wells used for groundwater moni-
toring:
*
• single screen wells, which sample a single vertical inter-
val;
• multiple screen wells, which sample more than one vertical
interval;
• well clusters, or a set of single wells placed closely
together, which sample more than one vertical interval; and
• piezometers, which measure the hydrostatic pressure of the
water table.
These are shown, iruFigures 5-3 through 5-6.
405
-------
FIGURE 5-3
SINGLE-SCREENED WELL
(Source: Fenn, et al., 1977)
Cap
Land Surface
Borehole
Schedule 40 PVC
Casing
Slotted Schedule
40 PVC Screen
Low Permeability
Backfill
Water Table
406
-------
FIGURE 5-4
MULTIPLE-SCREENED WELL PIMP
(Source: Fenn, et al., 1977)
SUSPENSION
CABLE
AIR LINE
WELL CASIN6
DISCHARGE LINE
SUBMERSIBLE PUMP
INFLATED RUBBER PACKER
CASING PERFORATION
PUMP INTAKE
INFLATED RUBBER PACKER
407
-------
FIGURE 5-5
WELL CLUSTER
(Source: Fenn, et al., 1977)
Well Casings
Land Surface
Sand
Backfill
in Screened
Interval
Low
Permeability
Material
408
-------
FIGURE 5-6
PIEZOMETER WELL
(Source: Fenn, et al. , 1977)
REMOVABLE
"PVC CAP
CEMENT OR
BENTONITE GROUT
SLOTTED SCHEDULE
40 PVC PIPE
•CONCRETE PLUG
SCHEDULE 40
PVC PIPE
SAND OR
GRAVEL PACK
409
-------
Monitoring wells, properly placed, can be used to characterize
the vertical and horizontal extent of groundwater contamination.
5.3.3.2 Status
Conventional, demonstrated. Well clusters have been the most
common and successful technique for delineating groundwater contam-
ination. (Fennetal., 1977)
5.3.3.3 Feasibility and Effectiveness
Well Types
Single-Screen wells-- Useful in two situations (Fenn et
al, 1977) :
• to obtain composite groundwater samples when screened (or
open) over, the entire saturated thickness of the aquifer;
and
• to sample deep aquifers when the major part of the sampling
program is aimed at the zone of aeration and the top of the
saturated zone.
They are not effective for determining the vertical distribu-
tion of contamination.
Multiple-Screen wells-- Effective for determining verti-
cal distribution of contamination if (Fenn et al. , 1977) :
• the packer pump and annular seal effectively isolate the
pumped portion from the rest of the aquifer; and
• pumping rates are kept low and pumping is not prolonged so
that water is drawn only from opposite the screened
section.
Well-clusters— The most common and successful technique
for determining vertical distribution of contamination. Well clus-
ters are not 100% effective, however, as portions of the vertical
area remain unsampled.
410
-------
If well clusters are constructed in a single, large-diameter
bore hole, the seals between individual wells must be carefully con-
structed and precautionary measures taken, such as using a
shrinkage-inhibitor in the grout. (Fenn et al., 1977)
Piezometers-- Must have an impermeable seal in the annular
space above the screen (Fenn et al., 1977). Therefore, any single-
screen monitoring well that meets RCRA requirements may also be used
as a piezometer.
Well Placement
No specific rules for the placement of monitoring wells are pos-
sible. Wells should be placed both upgradient and downgradient of
the site at strategic points in the aquifer(s) and throughout its
entire vertical depth.
In the simplest case, a single aquifer with uniform flow, a min-
imum of four wells are required to determine the direction of flow
and the hydraulic gradient. Three wells are used to determine the
plane of groundwater flow. A fourth, placed in the line of flow from
one of the other three, is then used to determine hydraulic
gradient. More wells are required for more complex aquifer systems.
Well placement depends on:
• depth to water table;
• direction of groundwater flow;
• hydraulic conductivity;
• effective porosity;
• hydraulic gradient;
• soil compaction;
• soil strength properties;
• leachate characteristics;
• economic considerations; and
• other site-specific considerations.
411
-------
Well Construction
Drilling techniques-- A list of techniques with maximum
drilling depth and typical well diameter is given in Table 5-2.
Drilling techniques, especially types of drilling mud used,
should be carefully selected so as not to interfere with sampling.
Selection of drilling technique will depend on:
• rock type;
• soil compaction;
• diameter and depth of well;
• site accessibility;
• availability of drilling water; and
• economic considerations.
Casing-- In general casing material should be:
• plastic if metal analysis is important. If depth < 16m (52
ft), use schedule 40 PVC, and if depth > 16m, use schedule
80 PVC (Absalon and Starr, 1980);
• steel if hydrocarbon analysis is important. (Mooij and
Rovers, 1976); and
• steel or wrought iron if considerable strength is required
during installation. (Walton, 1970).
Selection of casing material depends on
• parameters to be sampled;
* drilling technique;
• depth of well;
• leachate-characteristics; and
• groundwater quality (corrosive or encrusting).
412
-------
TABLE 5-2
DRILLING TECHNIQUES
Technique
Dug
Augered
Hand
Power
Driven
Jetted
Drilled
Cable tooled
Rotary
Max. Depth (m)
13 (40ft)
6.5 (20)
65 (200)
10 (30)
50 (150)
100 (300-small rig)
2300 (7000-large rig)
"
Typical
Well Diameter
2.5m (8ft)
5-1 Ocm (2-34 in.)
5-90cm (2-32in.)
4- llcm (1.5-4 in.)
5cm (2 in.)
14-65cm (5-24in.)
16-22cm'(6-8in.)
Comments
Generally not applicable
for monitoring
For unconsolidated
materials
For unconsolidated
materials
For unconsolidated
materials
Best in sandy soils
Good for sampling
and logging
Good for consolidated
materials
Source: Everett et al, 1976
-------
Diameter
A 5 cm (2 in.) inside casing diameter is most common. Typical
range for monitoring wells is 3 - 16cm (1.25 - 6 in. ) . (Mooij and
Rovers, 1976. )
Screen
The choice of screen materials depends on the type of casing.
Plastic casing can be slotted in the field and covered with fiber-
glass cloth or encased with a sand or gravel pack. A sand or gravel
pack is appropriate in consolidated soils or in unconsolidated soils
with a permeability less than 10 - 2cm/sec. It should extend 16 - 32
cm (6 - 12 in) above and below the slotted area.Manufactured steel
screens are used for steel casings. Galvanized steel may affect
water quality analysis (Mooij and Rovers, 1976). Selection of
screen material depends on:
• parameters to be sampled;
• drilling technique;
• depth of well;
• leachate characteristics; and
• groundwater quality (corrosive or encrusting).
Slot size (the size of the screen opening) depends on the grain
size distribution, grading, and the structural integrity of the
aquifer material. Recommended slot sizes, based on the percentage
of aquifer material that should not pass through the screen, are
given in Table 5-3.
The screen should extend over entire vertical span of interest.
Annular Space
The annular space above (or between) sampling depths should be
sealed with impermeable material (such as cement grout or bentonite
slurry) to prevent contamination of samples with water from contam-
inating other aquifers. This is a requirement for monitoring wells
under RCRA.
414
-------
TABLE 5-3
SLOT SIZE
Slot Size
(%of aquifer
Aquifer Material Cave-in Potential material retained)
Artificial (sand or
gravel) pack — 90
Natural pack
Poorly graded NO 30
Poorly graded Yes 50
Well graded No 40
Well graded Yes 60
Source: Walton, 1970
Well Development
Wells should be developed (pumped out) before sampling and,
again, periodically during sampling to remove silt, fine sand, and
other materials from the zone immediately around the well.
(Everett, et al., 1976. ) Pumping should continue until measurements
of conductivity, chlorine, and hardness are consistent. In highly
permeable soils a minimum pumping volume of five well casing volumes
is recommended. In relatively impermeable soils wells should be
pumped dry and the incoming water analyzed. This process is
repeated until the above parameters are constant (Mooij and Rovers,
1976).
Special Precautions and Limitations
Drilling techniques, construction material and well design
should be carefully selected so as not to interfere with sampling.
5.3.3.4 Principal Data Requirements
The principal data considerations for monitoring wells are sum-
415
-------
marized in Table 5-4.
5.3.3.5 Elements of Cost Review
Components
Construction and Capital--
• well drilling
• pumps
• casing and screening material
• sealant for annular space
O & M--
• electricity for pump
• pump maintenance
• sample collection and analysis
Major Factors
• number and depth of wells
• casing and screening material
• pump size
• drilling technique
• sample analysis required
Data
Cost information for various types of monitoring wells are given
in Table 5-5.
416
-------
TABLE 5-4
PRINCIPAL DATA CONSIDERATIONS FOR MONITORING WELLS
Data Needed Well Placement Drilling Material Selection Slot Size
Site or material x
accessibility
Rock type X
Soil characteristics:
grain sized distribution X
compaction x X
strength (or structural) X X
properties
permeability X
porosity X
chemistry X
depth X X
Hydrology:
depth to water table x
hydraulic gradient x
(potentiometric surfaces)
groundwater quality X
rate and direction of x
groundwater
Waste description
(waste and leachate)
chemical characteristics x x
physical characteristics x x
Well characteristics XX x
Economics XX X
Source: ADL, 1976
-------
TABLE 5-5
COST ESTIMATES FOR MONITORING WELLS
Monitoring Technique &
Construction Method
Price Per Diameter of Installation Well (1982 dollars )
51mm (2-inch)
102mm (4-inch)
152mm (6-inch)
•e-
M
00
Screened over a single interval
(plastic screen and casing)
1. Entire aquifer
2. Top 3 meters (10 feet) of
aquifer
3. Top 1.5 meters (5 feet) of
aquifer with drive point
Piezometers
(plastic screen and casing)
1. Entire aquifer screened
a. Cement grout
b. Bentonite seal
2. Top 3 meters (10 feet) of
aquifer screened
a. Cement grout
b. Bentonite seal
Well clusters
1. Jet—percussion
a. Five-well cluster, each well
with a 6-meter (20-foot)
long plastic screen
b. Five-well cluster, each well
with only a 1.5-meter (5-foot)
long plastic screen
2. Augers
a. Five-well cluster, each well
with a 6-meter (20-foot)
long staineless steel wire-
wrapped screen
b. Five-well cluster, each well
with only a 1.5-meter (5-foot)
long gauze wrapped drive points
$2,770-6,400
1,040-1,820
170-350
3,630-8,130
3,200-7,180
1,990-3,550
1,560-2,, 600
4,300-6,570
2,940-3,980
7,960-9,170
3,110-4,500
$3,980-7,790
1,210-1,990
$11,070-12,980
4,840-9,520
4,070-8,560
2,080-3,720
1,640-2,770
11,940-14,710
11,500^13,750
-------
TABLE 5-5
COST ESTIMATES FOR MONITORING WELLS (Cont.)
Monitoring Technique &
Construction Method
Price Per Diameter of Installation Well
51mm (2-inch)
102mm (4-inch)
_( 1982 dollarsa)
152mm (6-inch)
3. Cable tool
a. Five-well cluster, each well
with a 6-meter (20-foot)
long stainless steel wire-
wrapped screen
4. Hydraulic rotary
a. Five-well cluster, each well
with a 6-meter (20-foot)
long plastic screen, casing
grouted in place
b. Five-well cluster, completed
in a single large-diameter bore-
hole 4.5-meter (15-foot) long
plastic screens, 1.5-meter
(5-foot) seal between screens
Single well/multiple sampling point
a. 33.5-meter (110-foot) deep
well with 1-foot long screens
separated by 1.2 meters (4 feet)
of casing starting at 3 meters
(10 feet) below ground surface
Sampling during drilling
$17,040-24,480
$15,660-25,780
23,880-33,560
$7,340-10,170
14,270-19,030
5,190-8,130
5,190-8,130
5,700-9,000
aCost estimates are for an aquifer composed of unconsolidated sand with a depth to water of 3 meters
(10 feet) and a total saturated thickness of 30 meters (100 feet). Costs have been updated to 1981
dollars based on rates prevailing in the Northeast in Autumn, 1975. Actual costs will be lower and
higher depending upon conditions in other areas. Therefore, the cost estimates will be most useful
in determining the relative cost relationships among the monitoring techniques.
Source: Fe.nn et al, 1977
-------
GLOSSARY1
CONTROL TECHNOLOGY TERMS
ABS pipe—Abbreviation for pipes made of acrylonitrile butadiene
styrene, a type of plastic.
annular space—The space in a well between the well casing and
sides of the borehole.
Aquifer Terms
confined—An aquifer is confined if the upper boundary of
the aquifer is determined by (or confined by) a relatively
impermeable stratum (called an aquitard). The potentio-
metric surface of a confined aquifer is generally higher
than this boundary.
drawdown—The change in height of the water table (for un-
confined aquifers) or potentiometric surface (for confined
aquifers) radially around a well due to pumping.
v
homogeneous—An aquifer is homogeneous if the hydraulic
conductivity is independent of position in the aquifer.
At any two given points, therefore, hydraulic conductivity
will be the same. Aquifers which do not have this charac-
teristic are heterogeneous.
hydraulic conductivity—A measure of the rate at which flu-
id flows through a porous medium. It is a function of the
characteristics of both the fluid and the medium. It is
sometimes called the coefficient of permeability.
hydraulic gradient—The rate of change in hydraulic head
between two points. It indicates the direction in which
water will flow.
The Glossary is divided into two sections: Control Tech-
nology Terms (from Section 3) and Treatment Technology
Terms (from Section 4). In addition, terms pertaining to
aquifers and to soil are grouped together.
420
-------
hydraulic head—The sum of the fluid pressure due to water
depth (pressure head) and elevation above an arbitrary da-
tum (elevation head). This determines how high water will
rise in a well penetrating the aquifer to a given depth.
isotropic—An aquifer is isotropic if the hydraulic conduc-
tivity is independent of the direction of flow. At any
given point, therefore, vertical hydraulic conductivity is
equal to horizontal hydraulic conductivty. Aquifers which
do not have this characteristic are anisotropic.
leaky—An aquifer is leaky if there is inflow or outflow
through the underlying or confining layer (i.e., the under-
lying or confining layer is "leaky"). (Freeze and Cherry,
1979).
potentiometric surface—An imaginary surface defining the
height to which water would rise in a series of wells pene-
trating an aquifer. It is a measure of the hydraulic head
of the aquifer. It is also called a piezometric surface.
specific yield—Volume of water yielded per unit surface
area per unit drop in the water table in an unconfined
aquifer. In a confined aquifer, this is called the stora-
tivity and is defined in terms of a unit drop in the poten-
tiometric surface.
transmissivity—An expression of the amount of water that
can be extracted from an aquifer in a given amount of time.
Typical FPS units are gals/day/ft and SI units are m /s.
It is defined as the hydraulic conductivity times the
saturated thickness of the aquifer (Freeze and Cherry,
1979) .
unconfined—An aquifer is unconfined when the water table
defines the upper boundary of the aquifer (Freeze and
Cherry, 1979) . The potentiometric surface of an uncon-
fined aquifer is generally at the water table. Unconfined
aquifers are also called water table or phreatic aquifers.
backfill—"The operation of refilling an excavation. Also the
material placed in an excavation in the process of backfilling"
(EPA, 1976, Vol. 1).
banquette—A local extension of the land side slope of a dike
constructed to provide construction access or added stability
where required (SCS, 1972).
bedrock—Relatively impermeable rock "lying in the position
where it was formed and not underlain by any material other
than rock" (Merritt, 1976).
421
-------
bentonite—A clay made of decomposed volcanic ash which swells
when wetted (Merritt, 1976).
diatomaceous earth—Deposits of well-graded silaceous phyto-
plankton
(diatoms) the size of very fine silt used primarily as
a filter medium.
diversion—The combination of a dike and a channel constructed
immediately upslope of the dike, used to intercept surface
flow.
drainage area—That portion of the land surface which naturally
drains across a given line of interest. It is an important
factor in determining the quantities of water that can arrive
at surface water control structures.
eutrophic—A condition in a body of water which promotes nui-
sance algae growths. It is usually caused by high nutrient
concentrations.
fetch—Distance of open water, used in calculating wave height.
freeboard—The distance between design peak water levels and
the top of a structure such as a levee or dike. It is espe-
cially important for earthen structures in providing a measure
of safety to prevent overtopping.
gabion—A mesh container filled with rocks or stones used in
the construction of dams, channels, and basin sidewalls (EPA,
1976, Vol. 1).
grade—The angle of a structure across the slope. A dike of 0%
grade would, therefore, cause water to pond behind it while a
positive grade would allow water to flow along the dike.
groundwater (or water) table—The upper limit of the part of
the soil or underlying rock material that is wholly saturated
with water. The locus of points in soil water at which the
hydraulic pressure is equal to atmospheric pressure (EPA, 1976,
Vol. 1) .
gunite—A trademark for a concrete mixture sprayed under pres-
sure over steel reinforcements.
neoprene—A synthetic rubber produced by the polymerization of
chloroprene; it is highly resistant to 'oil, heat, light and
oxidation.
422
-------
nomograph—A diagram used with a straight edge to find depen-
dent variables when independent variables are given. For
example, given slope, discharge, and velocity of a parabolic
channel, it is possible using a nomograph to find necessary top
width and channel depth.
Number 200 sieve—Instrument which allows only soil with parti-
cle size smaller than fine sand (.074mm) to pass through.
Proctor density—Maximum density on a smooth curve of dry soil
density versus soil moisture content determined by the standard
Proctor density test. Also called the standard American Asso-
ciation of State Highway Officials (AASHO) density.
PVC—Abbreviation for polyvinylchloride; a type of plastic.
remedial action—Defined by CERCLA, section 101(24), as "those
actions taken ... in the event of a release or threatened
release of a hazardous substance into the environment, to
prevent or minimize the release of hazardous substances so that
they do not migrate to cause substantial danger to present or
future public health or welfare or the environment." In the
context of this report it also includes removal actions.
riprap—Broken rock, cobbles, boulders, or similar material
placed on earth surfaces such as a levee or dike, for protec-
tion against soil erosion due to the action of water (EPA,
1976, Vol. 1).
runoff—Any water, leachate or liquid which flows over land
from onsite to offsite, or that portion of precipitation which
flows overland.
runon—Any water, leachate, or liquid which flows from offsite
to onsite.
sec-marsh—A unit of viscosity. It is measured by means of a
standard test using a marsh funnel. A liquid which takes 40
seconds for 964 cubic centimeters to drain from a marsh funnel
is said to have a viscosity of 40 sec-marsh. Water has a
viscosity of 28 sec-marsh.
slope—Rate of change in elevation of the land surface. A
slope defined by a horizontal distance of two meters and a
vertical rise of one meter can be expressed as a fraction (1/2
or .5), a percent (50%), or a ratio (2:1).
slope length—The distance along a slope between successive
natural or man-made obstacles which impede the flow of surface
water. It is an important factor in determining a slope's
resistance to erosion.
423
-------
slope steepness—The average slope of the land surface. It is
an important factor in determing a slope's resistance to ero-
sion.
Soil Terms
soil—"1. The unconsolidated mineral and organic material
on the immediate surface of the earth that serves as a nat-
ural medium for the growth of land plants. 2. A kind of
soil; that is, the collection of soils that are alike in
specified combinations of characteristics. Kinds of soil
are given names in the system of soil classification. The
terms 'the soil' and 'soil1 are collective." (EPA, 1976,
Vol. 1).
grain size distribution—A plot of the percent, by weight,
of soil material retained versus the logarithm of the sieve
opening.
permeability—"The ability of a soil to conduct or dis-
charge water under a hydraulic gradient." It is a func-
tion of particle size, soil density, and degree of satura-
tion (Merritt, 1976).
plasticity—The ability of a soil "to deform rapidly with-
out cracking, crumbling, or volume change and with rela-
tively small rebound when the deforming force is removed."
(Merritt, 1976).
porosity—Percent void space (filled with air or other flu-
id) in a soil.
strength properties—Properties of a soil which determine
important characteristics such as ultimate bearing capac-
ity, stability of embankments, and pressure against under-
ground walls or barriers (Merritt, 1976) . These proper-
ties include soil density, consistency, compressibility,
and shearing strength.
texture—Measures the appearance of the soil in terms of
particle size, shape, and gradation. It is important in
determining other properties, such as maximum density, com-
pressibility, and others (Merritt, 1976).
stabilize—To "settle, fix in place, make non-moving" (EPA,
1976, Vol. 1), often by means of vegetation or placement of sur-
face materials such as straw. It usually refers to holding
soil in place to prevent erosion or to allow seed to take root.
staging area—A section of a site with adequate controls (e.g.,
paved and drained, runon prohibited) for the safe storage and
handling of drummed waste or other hazardous materials.
424
-------
straw-bale check dam—A temporary barrier constructed of staked
down straw bales used to intercept sediment or slow down chan-
nel flow to allow vegetation to take hold. It has a life expec-
tancy of three months or less. (EPA, 1976, Vol. 2).
swale—"A ditch, hollow, or depression." (EPA, 1976, Vol. 1).
transpiration—Water loss from leaves and other plant organs to
the atmosphere.
24-hour, 25-year rainfall—The intensity and quantity of water
discharged by a storm with a 24-hour duration which has the
probability of occuring once every 25 years. It has a 4%
chance of occuring in any given year.
uncontrolled hazardous waste disposal sites—Refers to a site
where hazardous wastes have been disposed or spilled in such a
way as to pose a threat to human welfare or the environment.
Also called abandoned or inactive hazardous waste sites.
TREATMENT TECHNOLOGY TERMS
aerobic—Refers to biological processes which require molecular
oxygen.
alcohols—A class of organic compounds characterized by a hy-
droxyl group. Methanol, ethanol, and propanol are examples of
alcohols.
aliphatics—a class of organic compounds characterized by a
chain arrangement of carbon atoms (Hawley, 1981).
amines—A class of organic compounds characterized by ammonia
with one or more hydrogens replaced by an alkyl group.
ammonia—A colorless gas composed of nitrogen and hydrogen atoms
which is extremely soluble in water.
anaerobic—Refers to biological processes which require the ab-
sence of molecular oxygen.
aromatics—A class of organic compounds characterized by one or
more cyclic rings which contain double bonds. Benzene is a
prominent member of this class.
asphaltic bitumen—black or dark colored cement-like substance
composed mainly of high molecular weight hydrocarbons (TRD 4) .
425
-------
BOD (Biological Oxygen Demand)—"A measure of the relative oxy-
gen requirements of waste-waters, effluents and polluted waters.
BOD values cannot be compared unless the results have been ob-
tained under identical test conditions. The test is of limited
value in measuring the actual oxygen demand of surface waters."
(TRD 4).
COD (Chemical Oxygen Demand)—"A measure of the oxygen equiva-
lent of that portion of the organic matter in a sample that is
susceptible to oxidation by a strong chemical oxidant." (TRD
4) .
colloidal particles—"Particles that are so small that the sur-
face activity has an appreciable influence on the properties of
the particle." (TRD 9).
cyanide—A class of compounds characterized by the presence of
a cyanide group which consist of a carbon atom triply bonded to
a nitrogen atom.
detention time—The time period that a waste stream is retained
in contact with a treatment process, also referred to as reten-
tion time.
EDTA—Ethylenediamine tetraacetic acid.
effluent—"A waste product discharged from a process" (EPA,
1980) .
elutriate—Liquid phase of a wash which is recovered by filter-
ing or decanting.
ethers—A class of organic compounds characterized by an oxygen
molecule singly bonded to two organic groups of atom; i.e.,
R-O-R where R represents an organic group.
flocculation—"The coalescence of a finely-divided precipitate"
(EPA, 1980).
halocarbons—A class of organic compounds which contain carbon,
one or more halogens, and sometimes hydrogen (Hawley, 1981).
influent—"A process stream entering the treatment system"
(EPA, 1980) .
immiscible—liquids which cannot be mixed or blended to form a
uniform solution (e.g., oil and water).
insolation—Average solar flux reaching the earth's surface, in
watts per square meter.
426
-------
leachate—Any liquid, including any suspended components in the
liquid, that has percolated through or drained from hazardous
wastes (Fed. Reg. 45, 33075, May 19, 1980).
leachate plume—The volume which encompasses the spread of
leachate from its source.
metals—Elements which form positive ions when their salts are
dissolved in-water (Hawley, 1981).
MLVSS (mixed liquor volatile suspended solids)—Concentration
of volatile suspended solids in a waste water and microorganisms
mixture of an activated sludge treatment process. Volatile sus-
pended solids are the fraction of total suspended solids which
are combustible at 550°C. Volatile suspended solids levels
are a rough approximation of the organic portion of the total
suspended solids (EPA, 1971).
nitrification—oxidation of nitrogen to nitrates; typically in
biological waste treatment nitrogen present in ammonia is oxi-
dized to form nitrate ions.
129 Priority Pollutants—List of toxic pollutants for which the
EPA is required to publish effluent standards under Sec 307 of
the Clean Water Act of 1977.
organics—Compounds containing carbon.
PCBs (Polychlorinated biphenyls)—A group of toxic chlorinated
hydrocarbons most commonly used as heat transfer fluids. PCBs
are persistent in the environment and are a suspected carcino-
gen.
pesticide—"A broad term, that includes all chemical agents used
to kill animal and vegetable life which interfere with agricul-
tural productivity regardless of their mode of action." (TRD
4). DDT, chlordane, aldrin, and dieldrin are examples of pesti-
cides.
phenols—A class of organic compounds characterized by one or
more hydroxy groups bonded to a benzene ring (Hawley, 1981).
phthalates—A class of organic compounds characterized by adja-
cent ester groups attached to a benzene ring. Examples of
phthalates are Di-N-Butylphthalate, Diethylphthalate, and
Phthalimide.
polynuclear aromatics—A class or organic compound characterized
by three or more aromatic rings.
427
-------
post treatment—Processing of waste streams to remove secondary
pollutants which have been subject to a treatment process de-
signed to remove the object pollutants; e.g., denitrification
of a waste water stream after biological treatment to lower BOD.
pretreatment—Processing of waste streams prior to a treatment
process designed to remove the object pollutants; e.g., equali-
zation and/or pH adjustment prior to biological treatment to re-
duce a wastewater BOD.
reagent—"Any substance used in a reaction for the purpose of
detecting, measuring, examining, or analyzing other substances"
(Hawley, 1981) .
sludge—"any solid, semisolid, or liquid waste generated from a
municipal, commercial, or industrial waste water treatment
plant, water supply treatment plant, or air pollution control
facility exclusive of the treated effluent from a wastewater
treatment plant." (TRD 6).
TDS (total dissolved solids)—"Solids capable of passing through
a standard glass fiber filter and dried to constant weight at
180°C" (EPA, 1971). Also referred to as filterable solids.
TKN (total Kjeldahl nitrogen)—The sum of free ammonia and or-
ganic nitrogen compounds which are converted to ammonia sulfate
under conditions described in the reference EPA, 1971.
treatment—"Any method, technique, or process, including neu-
tralization designed to change the physical, chemical, or bio-
logical character or composition of any hazardous waste so as
to neutralize such waste, or so as to recover energy or ma-
terial resources from the waste, or so as to render such waste
non-hazardous or less hazardous; safer to transport, store, or
dispose of; or amenable for recovery, amenable for storage, or
reduced in volume." (TRD 6).
TSS (total suspended solids)—"Solids that either float on the
surface of or are suspended in water, wastewater, or other liq-
uids, and which are largely -removable by laboratory filtering
as described in "Standard Methods of the Examination of Water
and Wastewater," and referred to as nonfilterable residue."
(TRD 4).
zeolites—Hydrated silicates of aluminum and sodium and/or cal-
cium which are used as ion exchange resins.
428
-------
REFERENCES
TECHNICAL RESOURCE DOCUMENTS (TRDs)
1. Lutton, R.J., "Evaluating Cover Systems for Solid and Haz-
ardous Waste," TRD 1, EPA Report No. SW-867, Cincinnati, OH
(Sept., 1980). PB 81-166-340
2. Perrier, E.R. and A.C. Gibson, "Hydrologic Simulation on
Solid Waste Disposal Sites," TRD 2, Final Report to SHWRD,
MERL. EPA Report No. SW-868, Cincinnati, OH (Sept.,
1981). PB 81-166-332
3. Moore, C.A., "Landfill and Surface Impoundment Performance
Evaluation Manual," TRD 3, Final Report to SHWRD, MERL.
EPA Report No. SW-869, Cincinnati, OH (Sept., 1980). PB
81-166-357
4. Matrecon, Inc., "Lining of Waste Impoundment and Disposal
Facilities," TRD 4, Final Report to SHWRD, MERL. EPA Re-
port No. SW-870, Cincinnati, OH (Sept., 1980). PB 81-166-
365
5. Shuckrow, A.J., A.P. Pajak and C.J. Touhill, "Management of
Hazardous Waste Leachate," TRD 5, Final Report to SHWRD,
MERL. EPA Report No. SW-871, Cincinnati, OH (Sept.,
1980). PB 81-166-354
6. U.S. Army Engineers Waterways Experiment Station, "Guide to
the Disposal of Chemically Stabilized and Solidified
Waste," TRD 6, Final Report to SHWRD, MERL. EPA Report
No. SW-872, Cincinnati, OH (Sept., 1980). PB 81-166-505
7. Wyss, A.W., H.K. Willard, R.M. Evans, R.J. Schmitt, R.G.
Sherman, D.H. Bruehl and E.M. Greco, "Closure of Hazardous
Waste Surface Impoundments," TRD 7, EPA Report No. SW-873,
Cincinnati, OH (Sept., 1980). PB 81-166-894
8. K.W. Brown and Associates, Inc., "Hazardous Waste Land
Treatment," TRD 8, Final Report to SHWRD, MERL. EPA No.
SW-874, Cincinnati, OH (Sept., 1980). PB 81-166-107
9. Roberts, D.W. and M.A. Nichols, "Soil Properties, Classifi-
cation and Hydraulic Conductivity Testing," TRD 9.
429
-------
10. Pettyjohn, W.A., B.C. Kent, T.A. Prickett and H.E. LeGrand,
"Methods for the Prediction of Leachate Plume Migration and
Mixing," TRD 10, Draft Report to SHWRD, MERL. Cincinnati,
OH.
11. SCS Engineers, "Evaluation of Closure and Post-Closure Care
Plans for Hazardous Waste Landfills," TRD 11, Cincinnati,
OH (Jan., 1982).
LITERATURE CITED
Absalon, J.R. and R.C. Starr, "Practical Aspects of Groundwater
Monitoring at Existing Disposal Sites," National Conference on
Management of Uncontrolled Hazardous Waste Sites, Hazardous Mate-
rials Control Research Institute, Silver Springs, MD (Oct. 15-
17, 1980).
Adams, C.E., Jr. and W.W. Eckenfelder, Jr., Process Design Tech-
niques for Industrial Waste Treatment, Enviro Press, Nashville,
TN, (1974) .
American Society of Agricultural Engineers. ASAE Standard: ASAE
5268.2. Design, Layout, Construction and Maintenance of Terrace
Systems, St. Joseph, MI, (1978).
American Society of Civil Engineers, "Backhoe with Record Length
Expedites Slurry-Trench Construction," Civil Engineering, ASCE.
August, 1982, Vol. 52, Number 8, p. 64.
Arthur D. Little, Inc. "Installation Restoration Simulation and
Cost/Benefit Analysis. Vol III Environmental Containment," Final
Report to CDR/ARRAD COM, CML/3 Ballistics Procurement Division,
Contract No. DAAK11-78-C-0108 (Jan., 1983^
Arthur D. Little, Inc., "Physical, Chemical and Biological Treat-
ment Techniques for Industrial Wastes," Report to U.S. EPA, Office
of Solid Waste Management Programs, (Nov., 1976). Available
through NTIS, Report No. PB-275-054/5GA (Vol. I) and PB-275-
278/1GA (Vol. II).
Brown, R.A. and C.L. Timmerman, "In Situ Thermoelectric Stabili-
zation of Radioactive Waste," PNL-SA-9924, presented at Waste
Management 1982 Meeting, Tucson, AZ (March.8-11, 1982)
430
-------
Brunsing, T.P., W.E. Grube, and W.J. Davis-Hoover, "A Block Dis-
placement Technique to Isolate Uncontrolled Hazardous Waste
Sites": to be presented at the Third National Conference on Manage-
ment of Uncontrolled Waste Sites, Washington, D.C., (November 29
- December 1, 1982).
Calleyly, A.G., C.F. Foster and D.A. Stafford (eds.), Treatment
of Industrial Effluents, John Wiley & Sons, Inc., NY (1976).
Campbell, M.D. and J.H. Lehr, Water Well Technology. McGraw-
Hill Book Company, NY (1974).
Carlson, J., "Recovery of Landfill Gas at Mountain View: Engi-
neering Site Study," EPA, Washington, D.C. Report No. EPA-530/
SW-587d (1977).
Chang, Howard H., "Stable Alluvial Canal Design," ASCE Journal
of the Hydraulics Division, Vol. 106, No. H45, pp. 873-891 (May,
1980) .
Chemical Engineering, Vol 88, No. 20, p. 51 (Oct. 5, 1981).
Chemical Marketing Reporter, "Current Prices of Chemicals and
Related Materials," Vol 219, No. 25 (June 22, 1981).
Cleary, J.M., "A Method for Displacing Large Blocks of Earth"
U.S. Patent No. 4, 230, 368 (February, 1979).
D'Appolonia, D.J., "Soil-Bentonite Slurry Trench Cutoffs,"
Journal of the Geotechnical Engineering Division, ASCE, Vol. 106
_4:399-418 (April, 1980).
Davis, Raymond E., Francis S. Foote and J.W. Kelly, Surveying
Theory and Practice, McGraw-Hill Book Co., NY (1966).
Doering, Eugene J. and Leo C. Benz, "Pumping an Artesian Source
for Water Table Control," Journal of the Irrigation and Drainage
Division, ASCE (June, 1972).
Duke, James A. "The Quest for Tolerant Germplastic (Chapter 1),"
Crop Tolerance to Suboptimal Land Conditions, ASA, Madison, Wiscon-
sin (1978) .
Environmental Protection Agency (EPA) Technology Transfer,
"Environmental Pollution Control Alternatives: Economics of
Wastewater Treatment Alternatives for the Electroplating Industry,"
Report No. 625/5-79-016 (June, 1979).
EPA, Technology Transfer, "Erosion and Sediment Control, Vol. I
and II," Report No. G25/3-76-006 (Oct., 1976).
431
-------
EPA, Technology Transfer, "Handbook for Remedial Action at Waste
Disposal Sites," Final Report to OERR, ORD, MERL. EPA Report
No. EPA-625/6-82-006 (June, 1982).
EPA, Technology Transfer, "Process Design Manual for Carbon Adsorp-
tion." (1973).
EPA, Technology Transfer, "Process Design Manual for Land Treat-
ment of Municipal Wastewater," USEPA Center for Environmental
Research Information, Cincinnati, OH (Oct., 1981).
EPA, "Treatability Manual," Vols. I, II, III, IV, V, Report Nos.
EPA-600/8-80-042 a-e Office of Research and Development, Wash-
ington, D.C. (July, 1980).
EPA, "Guidance Manual for Minimizing Pollution from Waste Disposal
Sites," Report No. 600/2-78-142, Municipal Environmental Research
Laboratory, Cincinnati, OH (August, 1978) .
Esposito, M.P. and S.M. Bronberg, "Fugitive Organic Emissions
from Chemical Waste Dumpsites," Paper presented at 74th Annual
Meeting of the Air Pollution Control Assoc., Philadelphia, PA
(June 21-26, 1981).
Evans, J. et al., "Setting Priorities for the Control of Partic-
ulate Emission from Open Sources," presented at Symposium on the
Transfer and Utilization of Particulate Control Technology, Vol.
4, U.S. EPA, EPA No. 600-/7-79-044d (February, 1979).
Everett, L.G., K.D. Schmidt, R.M. Tinlin and O.K. Todd, "Monitor-
ing Groundwater Quality: Methods and Costs," EPA Report No.
600/14-76-023 (May, 1976). Available fromNTIS, PB 257-133.
Everett, L.G., L.G. Wilson and L.G. McMillion, "Vadose Zone Monitor-
ing Concepts for Hazardous Waste Sites," Ground Water, _2_0 (1982).
Fair, G.M., J.C. Geyer and D.A. Okun, Water and Wastewater Engi-
neering, Vol. II, John Wiley & Sons, Inc., NY (1968).
Federal Register £5;33075 (May 19, 1980).
Fenn, D., E. Cocozza, J. Isbister, 0. Braids, B. Yare and P. Ronx,
"Procedures Manual for Groundwater Monitoring at Solid Waste Disposal
Ficilities," EPA No. 530/SW-611 (Aug., 1977).
Finkel, A.M. and R.S. Golob, "Implication of the Chemical Control
Corp. Incident," National Conference on Management of Uncontrolled
Hazardous Waste Sites (Oct. 28-30, 1981).
Freeze, R.A. and J.A. Cherry, Groundwater, Prentice-Hall, Inc.,
Englewood Cliffs, NJ (1979).
432
-------
Frogge, Richard R. and Glen D. Sanders, "USER Subsurface
Drainage Design Procedure," Water Management for Irrigation and
Drainage pp. 30-46 (July 20-22, 1977).
Ghassemi, Masood et al., "Feasibility of Commercialized Water
Treatment Techniques for Concentrated Waste Spills," TRW Environ-
mental Engineering Division, Redondo Beach, Calif. Report No.
PB82-1-8440 or EPA-600/2-81 213 (Sept., 1981).
Gilman, Edward F., I.A. Leone and F.B. Flower, "Critical Factors
Controlling Vegetation Growth on Completed Sanitary Landfills,"
EPA No. 600/52-81-164 (Sept., 1981).
Goldberg Zoino Associates (GZA), personal conversation with Charles
Lindburg, 1982.
Grim, E.G. and R.D. Hill, "Environmental Predictions in Surface
Mining of Coal," EPA Report No. 670/2-74-093 (1974).
Hager, D.G., "Industrial Wastewater Treatment by Granular Activated
Carbon," Industrial Waste Engineering., pp. 14-28 (Jan./Feb., 1974).
Haliburton Services, "Grouting in Soils," Vols. 1, 2, prepared
for Fed. Highway Administration, NTIS No. PB-259-043, 4 (1976).
Hammer, M.J., Water and Wastewater Technology, John Wiley & Sons,
Inc., NY (1975) .
Hawley, G. The Condensed Chemical Dictionary, Tenth Edition, Van
Nostrand Reinhold Co., NY (1981).
Healey, K.A. and R. Laak, "Site Evaluation and Design of Seepage
Fields," Journal of the Environmental Engineering Division, ASCE
(Oct., 1974) .
Herman, G.J., J.J. Twitchell and D.A. Lawrence, "Designing Monitor-
ing Programs for Different Land Application Projects," Paper No.
76-2067, presented to the American Society of Agricultural Engineers
(June, 1976) .
Horton, K.A., R.M. Morey, L. Isaacson and R.H. Beers, "The Comple-
mentary Nature of Geophysical Techniques for Mapping Chemical
Waste Disposal Sites: Impulse Radar Resistivity," National Conference
on Management of Uncontrolled Hazardous Waste Sites HMCRI, Silver
Springs, MD (Oct. 15-17, 1981).
Hwang, S.T., "Hazardous Air Emissions from Land Disposal/ Treatment
Facilities," Paper presented at the 74th Annual Meeting of the
Air Pollution Control Assoc., Philadelphia, PA (June 21-26, 1981).
433
-------
Kastman, K., "Cyanide Waste Disposal Site Neutralization," Proceed-
ings of the Conference on Geotechnical Practice for Disposal of
Solid Waste Materials, pp. 831-849, University of Michigan, Ann
Arbor, MI (June 13-15, 1977).
Kirk and Othmer Chemical Grouts, Vol. 5, pp. 368-874, John Wiley
& Sons, Inc., NY (1979).
Johnson, T.M., K. Cartwright and R.M. Schuller, "Monitoring of
Leachate Migration in the Unsaturated Zone in the Vicinity of
Sanitary Landfills," Ground Water Monitoring Review, Vol. 1, No.
3, pp. 55-63 (fall, 1981) .
JRB Associates, Inc., "Background Document for Modification of
pH Effluent Limitation Guidelines and Standards for Point Sources
Required by NPDES Permit to Monitor Continuously for Effluent
pH," Final Report to EPA, Contract No. 68-61-6048
Lambe, T.W. and R.V. Whitman, Soil Mechanics, John Wiley & Sons,
Inc., NY (1969).
LaRiviere, J.N.M., "Microbial Ecology of Liquid Waste Treatment,"
in Advances in Microbial Ecology, M. Alexander (ed.), Plenum Press,
NY (1977) .
Linsley, R.K. and J.B. Franzini, Water Resources Engineering,
McGraw-Hill Book Company, NY (1979) .
Lutton, et al., "Design and Construction of Covers for Solid Waste
Landfills," Report No. EPA-600/2-79-165 (Aug., 1979).
Marek, Charles R., "Compaction of Graded Aggregate Bases and Sub-
bases," Transportation Engineering Journal, ASCE (Jan., 1977).
Merritt, Fredrick S. ed., Standard Handbook for Civil Engineers,
McGraw-Hill Book Company, NY (1976) .
Metcalf and Eddy, Inc., Wastewater Engineering: Treatment, Disposal
Reuse, 2nd edition, McGraw-Hill Book Co., NY (1979).
Miller, R.A., R.D, Fox and D.M. Pitts, "Evaluation of Catalyzed
Wet Air Oxidation for Treating Hazardous Waste, Proceedings of
the 7th Research Symposium, EPA 600/9-81-002b, USEPA, Cincinnati,
OH (March, 1981).
Miller, R.A. and J.Y. Perez, "Current U.S.A. Practice: Slurry
Wall Specifications," Journal of the Geotechnical Engineering
Division, ASCE, Vol. 107 8/.1041-1056 (Aug., 1981).
Mooij, H. and F.A. Rovers, "Recommended Groundwater and Soil Sampling
Procedures," Environment Canada, Solid Waste Management Branch,
Report No. EPS-4-EC-76-7 (June, 1976).
434
-------
Nichols, H.L., Jr., Moving the Earth, North Castle Books, Greenwich,
CT (1962).
Overcash, M.R. and D. Pal, Design of Land Treatment Systems for
Industrial Wastes—Theory and Practice, Ann Arbor Science Publishers,
Inc., Ann Arbor, MI (1979).
Pease, R.W., Jr. and S.C. James, "Integration of Remote Sensing
Techniques with Direct Environmental Sampling for Investigating
Abandoned Hazardous Waste Sites," National Conference on Manage-
ment of Uncontrolled Hazardous Waste Sites (Oct. 28-30, 1981).
Pellizzari, E.D. and J.E. Bunch, "Ambient Air Carcinogenic Vapors,
Improved Sampling and Analytical Techniques and Field Studies,"
EPA Report No. 600/2-79-081 (May, 1979). Available from NTIS-PB297-
932.
Peters, J.A., K.M. Tackeh and E.G. Eimutis,"Measurement of Fugitive
Hydrocarbon Emissions from a Chemical Waste Disposal Site," National
Conference on Management of Uncontrolled Hazardous Waste Sites
(Oct. 28-30, 1981).
Pohland, F.G., "Sanitary Landfill Stabilization with Leachate
Recycle and Residual Treatment," EPA Report No. 600/2-75-043 (Oct.,
1975) .
Pound, C.E. and R.W. Crites, "Wastewater Treatment and Reuse by
Land Application—Volume I—Summary," EPA Report No. 660/2-73-
006a (Aug., 1973).
Prengle, H.W., Jr., C.E. Mack, R.W. Legan and C.G. Hewes III,
"Ozone/UV Process Effective Wastewater Treatment," Hydrocarbon
Processing, pp. 82-87 (Oct., 1975).
Reed, Sherwood C. et al, "Cost of Land Treatment Systems," 430/9-75-
003, USEPA Office of Water Program Operations, Washington, D.C.
(Sept., 1979).
Research and Education Assoc., "Modern Pollution Control Tech-
nology," Vols. I and II (1978).
Rhone, Thomas J., "Baffled Apron as Spillway Energy Dissipator,"
ASCE Journal of the Hydraulics Division, Vol. 103, No. HY12 pp.
1391-1402 (Dec., 1979).
Rishel, H.L., T.M. Boston and C.J. Schmidt, "Costs of Remedial
Response Actions .at Uncontrolled Hazardous Waste Sites," Draft
Report by SCS Engineers to SHWRD, MERL. Contract No. 68-07-4885
(April, 1981).
Schweitzer, Philip A. (ed.), Handbook of Separation Techniques
for Chemical Engineers, McGraw-Hill Book Company, NY (1979) .
435
-------
Shen, T.T. and T.J. Toffelmire, "Air Pollution Aspects of Land
Disposal of Toxic Wastes," Journal of the Environmental Engi-
neering Division, ASCE, Vol. 106, No. EEl, pp. 211-226 (Feb.,
1980) .
Smith, F.E., "Earthwork Volumes by Contour Method," ASCE Journal
of the Construction Division, Vol. 102, No C01, pp. 131-143 (March,
1976).
Soil Conservation Service, Drainage of Agricultural Land, U.S.
Dept. of Agriculture, Water Information Center, Inc., Port Washing-
ton, NY (1973).
Soil Conservation Service, Engineering Field Manual for Conser-
vation Practices, U.S. Department of Agriculture, Soil Conserva-
tion Service, Washington, D.C. (April, 1975).
Soil Recovery, Inc., company brochure, Morristown, NJ
Sommerer, S. and J.F. Kitchens, "Engineering and Development Support
of General Decon Technology for the DARCOM Installation and Restor-
ation Program, Task 1. Literature Review on Groundwater Containment
and Diversion Barriers," Draft Report by Atlantic Research Corp.
to U.S. Army Hazardous Materials Agency, Aberdeen Proving Ground,
Contract No. DAAK11-80-C-0026 (Oct., 1980).
Streeter, V.L. and B. Wylie, Fluid Mechanics (6th ed.), McGraw-
Hill Book Co., NY (1975).
Sullivan, D.A. and J.B. Strauss, "Air Monitoring of a Hazardous
Waste Site," National Conference on Management of Uncontrolled
Hazardous Waste Sites (Oct. 28-30, 1981).
Thibodeaux, Louis J. Chemodynamics; Environmental Movement of
Chemicals in Air, Water, and Soil, John Wiley & Sons, NY (1979).
Titus, S., "Survey and Analysis of Present/Potential Environmental
Impact Sites in Woburn, Massuchesetts," National Conference on
Management of Uncontrolled Hazardous Waste Sites, HMCRI, Silver
Springs, MD (Oct. 15-17, 1981).
Tolman, et al., Guidance Manual for Minimizing Pollution from
Waste Disposal Sites, EPA Report No. 600/2-78-142 (Aug., 1978).
Turpin, R.D., J.P. LaFornara, H.L. Allen and U. Frank, "Compati-
bility Field Testing Procedures for Unidentified Hazardous Wastes,"
National Conference on Management of Uncontrolled Hazardous Waste
Sites (Oct. 28-30, 1981).
Walton, W.C., Groundwater Resource Evaluation, McGraw-Hill Book
Company, NY (1970) .
436
-------
Wardell, John et al., "Contamination Control at Rocky Mountain
Arsenal, Denver, Colorado." USEPA, Management of Uncontrolled
Hazardous Waste Sites, Washington, D.C., pp 374-9. (Oct. 28-30,
1981)
White, G.C., Handbook of Chlorination, Van Nostrand Reinhold Co.,
NY (1972) .
Wilhelmi, A.R. and Knopp, "Wet Air Oxidation — An Alternative
to Incineration," Chemical Engineering Progress (reprint), (1979).
Wilkinson, R.R. and G.R. Cooper, "The Manufacture and Use of Selected
Inorganic Cyanides," Report to Office of Toxic Substances, EPA
Report No. 560/6-76-012 (Jan., 1976). Available through NTIS,
PB 251-820.
Wilson, L.G., "Monitoring in the Vadose Zone—Part I: Strange
Changes," Ground Water Monitoring Review, Vol. 1, No. 3, pp. 32-41
(fall, 1981).
Xanthakos, P.P., Slurry Walls, McGraw-Hill Book Company, NY (1979).
437
-------
COPYRIGHT NOTICE
Figure 3-2
Figure 3-3
Table 3-3
Figure 3-7
Figure 3-13
Figure 3-22
From "Soil-Bentonite Slurry Trench Cut-
offs", by D.J. D'Appolonia; Journal of
the Geotechnical Engineering Division,
ASCE, Vol. 106(4): 405 (April, 1980).
Used by permission of the American So-
ciety of Civil Engineers.
From "Soil-Bentonite Slurry Trench Cut-
offs", by D.J. D'Appolonia; Journal of
the Geotechnical Engineering Division,
ASCE, Vol. 106(4): 410 (April, 1980).
Used by permission of the American So-
ciety of Civil Engineers.
From "Soil-Bentonite Slurry Trench Cut-
offs", by D.J. D'Appolonia; Journal of
the Geotechnical Engineering Division,
ASCE, Vol. 106(4): 414 (April, 1980).
Used by permission of the American So-
ciety of Civil Engineers.
From Grouting in Soils by Haliburton
Services, Copyright 1976. Used by per-
mission of the Federal Highway Admini-
stration.
From Design, Layout, Construction and
and Maintenance of Terrace Systems,
ASAE 5268.2, 1978. Used by permission
of the American Society of Agricultural
Engineers.
From "Site Evaluation and Design of
Seepage Fields", by K.A. Healey and R.
Laak, Journal of the Environmental En-
gineering Division, ASCE, Vol. 100, No.
EE5, p. 1136 (October, 1974). Used by
permission of the American Society of
Civil Engineers.
438
-------
Figure 4-7 From Water and Wastewater Engineering
Vol. II by Fair, et. al. Copyright
1968 by John Wiley and Sons, Inc. Used
by permission of the publisher.
Figure 4-20 From Process Design Techniques for In-
dustrial Waste Treatment by C.E. Adams
and W.W. Eckenfelder, Jr. Copyright
1974 by Enviro Press. Used by permis-
sion of the publisher.
Figure 4-21 From Process Design Techniques for In-
dustrial Waste Treatment by C.E. Adams
and W.W. Eckenfelder, Jr. Copyright
1974 by Enviro Press. Used by permis-
sion of the publisher.
439
*US GOVERNMENT PRINTING OFFICE 1983-659-095/0740
------- |