EPA-625/1-78-010
SW-705
PROCESS DESIGN MANUAL
MUNICIPAL SLUDGE LANDFILLS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Environmental Research Information Center
Technology Transfer
Office of Solid Waste
October 1978
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NOTICE
The mention of trade names of
commercial products in this pub-
lication is for illustration
purposes and does not constitute
endorsement or recommendation
for use by the U.S. Environ-
mental Protection Agency.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Municipal sludge management is perhaps one of the most visible and
complex problems facing wastewater treatment authorities today. The
combination of greatly increased sludge volumes and the narrowing of
formerly used disposal options (such as ocean dumping) compounds this
problem. Congress, in enacting the Resource Conservation and Recovery
Act, and the Clean Water Act, acknowledged its concern over the
disposal of residuals resulting from the cleanup of our environment.
A common goal of these two acts is the conservation of natural
resources and energy through reuse waste materials.
EPA is committed to a residuals management program that will not only
protect public health and the environment but will maximize the use
of waste materials in beneficial ways. Specifically, management
technologies which recycle or reuse municipal sludges and thereby
contribute to energy and resource conservation are actively encouraged.
Unfortunately, beneficial utilization of sludge is not always
practicable or economical. Therefore, sanitary landfilling of
municipal sludge will continue as a .major disposal option. It is
the purpose of this manual to provide the engineering community,
related industry, and local government with a new source of information
for the planning, design and operation of municipal sludge landfills.
It has been written to provide design and operational guidance to
sanitary landfill operators and information to assist in the
preparation of sewage treatment plant construction grant applications.
The usefulness of this manual will be further enhanced with the
promulgation of sludge utilization and disposal guidelines that are
now being developed under the authority of Section 405 of the Clean
Water Act. The manual will provide publicly owned treatment works
with the detailed technical information needed to comply with the
landfilling portions of those guidelines.
S
teffen Plehn
/ Deputy Assistant Administrator
for Solid Waste
'John T. Rhett
Deputy Assistant Administrator
for Water Program Operations
Samuel Rondberg
Acting pirector
Office of Research
Program Management
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ACKNOWLEDGEMENTS
There were three groups of participants involved in the preparation of
this manual: (1) the contractor-authors, (2) the contract supervisors,
and (3) the review committee. The manual was written by personnel from
SCS Engineers. Contract supervision was provided by U.S. Environmental
Protection Agency (EPA) personnel from the Office of Solid Waste in
Washington, D.C., and from the Environmental Research Information Center
in Cincinnati, Ohio. The review committee was comprised of potential
manual users including regulatory officials, public and private
operators, and consultants. The Technical Practice Committee of the
Water Pollution Control Federation also reviewed the manual. The
membership of each group is listed below.
CONTRACTOR-AUTHORS: SCS Engineers
Direction: E. T. Conrad and R. Stearns, Principals
Senior Author: J. Walsh, Project Manager
Staff Authors: J. Atcheson, E. Bowring, W. Coppel, R. Lofy,
R. Morrison, D. Pearson, T. Phung, and D. Ross
Production Staff: L. Fauvie and C. Heglar
CONTRACT SUPERVISORS: U.S. Environmental Protection Agency
Project Officer: J. Perry, EPA Office of Solid Waste
Reviewers: J. E. Smith, Jr. and D. J. Lussier, EPA Environmental
Research Information Center
REVIEW COMMITTEE
M. Adams and M. Derdeyn, Browning-Ferris Industries
R. Bardwell, Gellman Research Associates
R. Bastian, EPA Office of Water Program Operations
D. Blackman, State of New York
W. Bucciarelli, State of Pennsylvania
A. Day, State of Maine
R. Domenowske, Municipality of Metropolitan Seattle
P. Dunlap, SCA Services
B. Fowler, Waste Management, Inc.
A. Geswein, EPA Office of Solid Waste
E. Higgins, EPA Office of Solid Waste
G. Lukasik, North Shore Sanitary District
R. Van Heuit, Los Angeles County Sanitation District
R. Williams, State of Georgia
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CONTENTS
Chapter Page
ACKNOWLEDGEMENTS in
CONTENTS v
LIST OF TABLES viii
LIST OF FIGURES x
FOREWORD xiii
1 INTRODUCTION
1.1 Sludge Disposal Alternatives 1-1
1.2 Sludge Landfills and Solid Waste
Disposal Facility Classification
Criteria 1-2
1.3 Objectives of Manual 1-3
1.4 Scope of Manual 1-3
1.5 Use of Manual 1-4
1.6 References 1-6
2 PUBLIC PARTICIPATION PROGRAM
2.1 Introduction 2-1
2.2 Objectives of a Public Participation
Program 2-1
2.3 Advantages and Disadvantages of a PPP 2-2
2.4 PPP Participants 2-3
2.5 Design of a PPP 2-4
2.6 Timing of Public Participation 2-9
2.7 Potential Areas of Public Concern 2-10
2.8 Conclusion 2-12
2.9 References 2-1?
3 SLUDGE CHARACTERISTICS AND LANDFILLING METHODS
3.1 Purpose and Scope 3-1
3.2 Sludge Sources 3-1
3.3 Sludge Treatment 3-3
3.4 Sludge Characteristics 3-10
3.5 Suitability of Sludge for Landfill ing 3-14
3.6 Sludge Landfill ing Methods 3-15
3.7 References 3-32
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CONTENTS (Continued)
Chapter Page
4 SITE SELECTION
4,1 Purpose and Scope 4-1
4.2 Site Considerations 4-1
4.3 Site Selection Methodology 4-14
4.4 Example of Methodology 4-19
4.5 References 4-28
5 DESIGN
5,1 Purpose and Scope 5-1
5,j2 Regulations and Permits 5-1
5.3 Design Methodology and Data Compilation 5-5
5.4 Selection of Landfilling Method 5-10
5.5 Sludge-Only Trench Designs 5-12
5.6 Sludge-Only Area Fill Design 5-20
5.7 Codisposal Designs 5-24
5.8 Environmental Safeguards 5-26
5r9 Storm Water Management 5-42
5.10 Access Roads " 5-44
5.11 Other Design Features 5-45
5.12 References 5-48
6 OPERATION
6.1 Purpose and Scope 6-1
6.2 Method-Specific Operational Procedures 6-1
6.3 General Operational Procedures 6-18
6.4 Equipment and Personnel 6-27
6.5 Reference 6-32
7 MONITORING
7T1 Introduction 7-1
7.2 Groundwater Monitoring 7-1
7.3 Surface Water Monitoring 7-13
7.4 Gas Monitoring 7-16
7.5 References 7-17
8 COMPLETED SITE
8.1 Introduction 8-1
8.2 Procedures for Site Closure 8-2
8,3 Characteristics of Completed Site 8-3
8.4 Completed Site Use 8-6
8.5 References 8-8
VI
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CONTENTS (Continued)
Chapter Page
9 MANAGEMENT AND COSTS
9.1 Introduction 9-1
9.2 Management Responsibility 9-1
9.3 Equipment Management and Documentation 9-3
9.4 Personnel Management and Recordkeeping 9-5
9.5 General Management and Recordkeeping 9-8
9.6 Cost Recordkeeping 9-13
9.7 Financing 9-16
9.8 Typical Costs 9-19
9.9 References 9-29
10 DESIGN EXAMPLES
10.1 Introduction 10-1
10.2 Design Example No. 1 10-1
10.3 Design Example No. 2 10-15
10.4 Design Example No. 3 10-27
11 CASE STUDIES
11.1 Introduction 11-1
11.2 Case Study Summaries 11-1
11.3 Montgomery County, Maryland 11-6
11.4Waukegan, Illinois 11-18
11.5 Colorado Springs, Colorado 11-36
11.6 Denver, Colorado 11-45
11.7 Lorton, Virginia 11-53
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TABLES
No. Page
2-1 Suggested Timing of Public Participation
Activities for Sample 15-Month Project 2-10
2-2 Capabilities of Public Participation Techniques 2-11
2-3 Public Concerns 2-11
3-1 Conversion Processes 3-8
3-2 Composition of Various Ashes 3-9
3-3 Typical Composition of Raw and Anaerobically
Digested Primary Sludges 3-11
3-4 Typical Quantities of Sludge Produced by Different
Treatment Processes 3-13
3-5 Chemical Composition of Municipal Wastewater Sludges 3-14
3-6 Suitability of Sludges for Landfilling 3-16
3-7 Sludge and Site Conditions 3-32
3-8 Design Criteria 3-33
4-1 Permeability Classes for Saturated Soil 4-6
4-2 Typical Ranges of Cation Exchange Capacity of
Various Types of Soils 4-7
4-3 Subsurface Logging Information Obtained by Various
Methods 4-11
4-4 Preliminary Investigations for Intitial Assessment 4-22
4-5 Investigation of Candidate Sites for Screening 4-24
4-6 Rating of Sites for Screening Using Scoring System 4-25
4-7 Operating Cost Estimates 4-26
4-8 Capital Cost Estimates 4-27
4-9 Final Site Selection 4-28
5-1 Analysis of Federal Criteria vs. State Regulations 5-4
5-2 Sludge Landfill Design Checklist 5-6
5-3 Sources of Existing Information 5-8
5-4 Field Investigations for New Information 5-9
5-5 Design Considerations for Sludge-Only Trenches 5-13
5-6 Alternate Design Scenarios 5-16
5-7 Design Considerations for Sludge-Only Area Fills 5-20
5-8 Design Considerations for Codisposal Operations 5-25
5-9 Range of Constituent Concentrations in Leachate
from Sludge Landfills 5-27
5-10 Attenuation and Permeability Properties of Clays 5-30
5-11 Attenuation Properties of Representative Soil Series 5-31
5-12 Liners for Sludge Landfills 5-34
5-13 Estimated Costs for Landfill Liners 5-35
5-14 Expected Efficiencies of Organic Removal from Leachate 5-38
5-15 Gas Concentrations at Selected Sludge Landfills 5-40
6-1 Environmental Control Practices 6-22
6-2 Inclement Weather Problems and Solutions 6-26
6-3 Equipment Performance Characteristics 6-28
6-4 Typical Equipment Selection Schemes 6-29
vm
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TABLES (Continued)
No. Page
7-1 Well Construction Details, Water Levels and Water
Quality (Physical) 7-7
7-2 Relative Abundance of Dissolved Solids in Potable
Water 7-12
7-3 Sample Size and Sample Preservation 7-14
8-1 Procedures for Site Closure 8-2
9-1 Cost Scenarios for Alternative Landfilling Methods 9-26
10-1 Estimate of Total Site Capital Costs for Example No. 1 10-14
10-2 Estimate of Annual Operating Costs for Example No. 1 10-14
10-3 Design Considerations for Example No. 2 10-20
10-4 Estimate of Total Site Capital Costs for Example
No. 2 - Wide Trench 10-25
10-5 Estimate of Annual Site Operating Costs for Example
No. 2 - Wide Trench 10-25
10-6 Estimate of Total Site Capital Cost for Example
No. 2 - Area Fill Mound 10-26
10-7 Estimate of Annual Site Operating Costs for Example
No. 2 - Area Fill Mound 10-26
10-8 Estimate of Total Annual Costs for Example No. 3 10-32
11-1 Site Identification and Sludge Description 11-3
11-2 Site Design and Operation 11-4
11-3 Hauling and Site Costs 11-5
11-4 Regulatory Requirements Relative to Site Selection
at Montgomery County, Maryland 11-8
11-5 Sampling and Analytical Program at Montgomery County,
MD 11-17
11-6 Details on Sludge Transported from Originating Plant
to Sludge Processing Unit at Waukegan, IL 11-18
11-7 Summary of Groundwater and Gas Wells and Surface
Water Stations at Waukegan, IL 11-33
11-8 Sampling and Analytical Program at Waukegan, IL 11-34
11-9 Summary of Sludge Generation and Transport to Lorton,
VA 11-53
11-10 Sampling and Analytical Program at Lorton, VA 11-63
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FIGURES
No. Page
1-1 Suggested Timing of Planning, Design, and Operation
Activities for Sample Landfill with Five Year Life 1-5
4-1 Sample Calculation: Area Required 4-3
4-2 Sample Calculation: Site Life Available 4-3
4-3 Soil Textural Classes and General Terminology Used
in Soil Descriptions 4-5
4-4 Soil Permeabilities and Sorbtive Properties of Selected
Soils 4-6
4-5 Unified Soil Classification System and Characteristics
Pertinent to Sludge Landfills 4-8
4-6 Hydrogeological Cycle 4-9
4-7 Site Selection Methodology 4-15
4-8 Initial Assessment with Overlays 4-20
5-1 Typical Site Preparation Plan 5-11
5-2 Trench Sidewall Variations 5-15
5-3 Cross-Section of Typical Marrow Trench Operation 5-17
5-4 Narrow Trench Operation 5-17
5-5 Wide Trench Operation 5-18
5-6 Cross-Section of Typical Wide Trench Operation 5-19
5-7 Cross-Section of Wide Trench with Dikes 5-19
5-8 Cross-Section of Typical Area Fill Mound Operation 5-22
5-9 Area Fill Mound Operation 5-22
5-10 Cross-Section of Typical Area Fill Layer Operation 5-23
5-11 Cross-Section of Typical Diked Containment Operation 5-24
5-12 Water Balance at Sludge Landfill 5-28
5-13 Underdrain for Leachate Collection 5-37
5-14 Upgrading Groundwater Interceptor Trench 5-37
5-15 Permeable Method of Gas Migration Control 5-41
5-16 Earthen Drainage Channel 5-43
5-17 CMP Drainage Channel 5-43
5-18 Stone Drainage Channels 5-44
5-19 Special Working Area 5-46
6-1 Narrow Trench Operation 6-5
6-2 Wide Trench Operation at Refuse Landfill 6-6
6-3 Wide Trench Operation with Dragline 6-7
6-4 Wide Trench Operation with Interior Dikes 6-8
6-5 Area Fill Mound Operation 6-13
6-6 Area Fill Layer Operation 6-14
6-7 Area Fill Layer Operation Inside 6-15
6-8 Diked Containment Operation 6-16
6-9 Sludge/Refuse Mixture Operation 6-19
6-10 Sludge/Refuse Mixture with Dikes 6-20
6-11 Sludge/Soil Mixture 6-21
6-12 Scraper 6-30
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FIGURES (Continued)
No. Page
6-13 Backhoe with Loader 6-30
6-14 Load Lugger 6-31
6-15 Trenching Machine 6-31
7-1 Landfill Water Balance Simplified 7-2
7-2 Water Table and Land Surface Contour Map with Test
Well Locations 7-6
7-3 Typical Monitoring Well Screened Over a Single
Vertical Interval 7-8
7-4 Typical Well Cluster Configurations 7-9
8-1 Infiltration Rates for Various Crops 8-7
9-1 Equipment Inspection Form 9-6
9-2 Landfill Safety Checklist 9-9
9-3 Daily Waste Receipt Form 9-11
9-4 Monthly Activity Form 9-12
9-5 Capital Cost Form 9-15
9-6 Operating Cost Form 9-16
9-7 Typical Hauling Costs 9-20
9-8 Typical Site Capital Costs for Sludge Landfilling 9-23
9-9 Typical Site Operating Costs for Sludge Landfilling 9-24
9-10 Typical Total Site Costs for Sludge Landfilling 9-25
10-1 Site Base Map for Example No. 1 10-5
10-2 Site Development Map for Example No. 1 10-9
10-3 Operational Procedures for Example No. 1 10-12
10-4 Site Base Map for Example No. 2 10-18
10-5 Site Development Plan for Example No. 2 - Wide Trench 10-21
10-6 Site Development Plan for Example No. 2 - Area Fill
Mound 10-22
11-1 Location of Case Study Sites 11-2
11-2 Blue Plains Treatment Plant Flow Diagram 11-6
11-3 Site Layout Plan - Montgomery County, MD 11-11
11-4 Narrow Trench Operation - Montgomery County, MD 11-13
11-5 Narrow Trench - Montgomery County, MD 11-14
11-6 Sludge Being Pumped Into Narrow Trench - Montgomery
County, MD 11-14
11-7 Application of Cover and Excavation of New Trench -
Montgomery County, MD 11-15
11-8 Sludge Processing at Originating Plant for North
Shore Sanitary District 11-19
11-9 Flow Diagram: Sludge Processing Unit at Waukegan, IL 11-20
11-10 Comparative Costs of Sludge Disposal Without Phosphorus
Removal at Waukegan, IL 11-22
11-11 Site Layout Plan - Wuakegan, IL 11-26
11-12 Wide Trench Operation - Waukegan, IL 11-28
11-13 Stockpiling Soil - Waukegan, IL 11-31
11-14 Unloading Sludge into Wide Trenches - Waukegan, IL 11-31
11-15 Placing Interim Cover - Waukegan, IL 11-32
11-16 Placing Final Cover - Waukegan, IL 11-32
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FIGURES (Continued)
No. Page
11-17 Schematic of Operating Practices at Colorado
Springs, CO 11-38
11-18 Wide Trench Operation - Colorado Springs, CO 11-39
11-19 Wide Trench - Colorado Springs, CO 11-42
11-20 Applying Cover to Sludge Deposits - Colorado Springs,
CO 11-42
11-21 Site Layout Plan at Colorado Springs, CO 11-43
11-22 Wastewater Treatment Flow Diagram for Denver, CO
Metro Plant 11-45
11-23 Area Fill Layer Operation - Denver, CO 11-49
11-24 Haul Vehicles - Denver, CO 11-50
11-25 Sludge Mixing Equipment - Denver, CO 11-50
11-26 Site Plan Layout at Lorton, VA 11-56
11-27 Spreading Sludge over Refuse - Lorton, VA 11-59
11-28 Sludge at Working Face - Lorton, VA 11-59
11-29 Covering Sludge/Refuse Mixture - Lorton, VA 11-60
11-30 Graded Site -- Lorton, VA 11-60
11-31 Codisposal Operation - Lorton, VA 11-61
xn
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FOREWORD
The formation of the United States Environmental Protection Agency marked
a new era of environmental awareness in America. This Agency's goals are
national in scope and encompass broad responsibility in the areas of air
and water pollution, solid wastes, pesticides, and radiation. A vital
part of EPA's national pollution control effort is the constant
development and dissemination of new technology.
It is now clear that only the most effective design and operation of
pollution control facilities, using the latest available techniques, will
be adequate to ensure continued protection of the Nation's resources. It
is essential that this new technology be incorporated into the
contemporary design of pollution control facilities to achieve maximum
benefit of our pollution control expenditures.
The purpose of this manual is to provide the engineering community and
related industry a new source of information to be used in the planning,
design and operation of municipal sludge landfills. It is recognized
that there are a number of design manuals, manuals of standard practice,
and design guidelines currently available. It is the intent of this
manual to supplement this existing body of knowledge.
Two major information sources were used to compile data for inclusion in
this manual. The first was a comprehensive literature review that
included publications, conference proceedings, unpublished information
from research projects, and product literature from equipment
manufacturers. The second was case study site investigations which
included a thorough inspection of on-site operating procedures and
interviews with landfill operating and management personnel.
A committee of experts in the planning, design, and operation of sludge
landfills was convened to review and finalize the manual outline; to
identify the needs of the potential users; and to discuss the material to
be included in the manual. Interim manual drafts were reviewed by EPA
personnel and the above-mentioned committee.
This manual is one of several available from Technology Transfer to
describe technological advances and new information. Future editions
will be issued as warranted by advancing state-of-the-art to include new
data as they become available, and to revise design criteria as
additional full-scale operational information is generated.
Companion publications describing alternative sludge treatment and
disposal methods are available in the form of Technology Transfer Seminar
Handouts. They may be obtained by writing:
U. S. EPA
ERIC
26 W. St. Clair
Cincinnati, Ohio 45268
xi ii
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CHAPTER 1
INTRODUCTION
1,1 Sludge Disposal Alternatives
Wastewater authorities today are faced with a dilemma. As improved
treatment technologies, more stringent regulatory requirements, and
increasing flows all produce greater quantities of sludge, phased
prohibition of ocean dumping, other regulatory constraints, and spiral ing
costs are combining to limit sludge disposal alternatives. Wastewater
authorities are effectively limited to two methods of disposal:
1. Conversion processes (incineration, pyrolysis, and composting)
2. Land disposal (landspreading and landfill ing)
Many communities have found conversion processes to be quite costly.
Specifically, incineration is becoming more costly because of energy cost
escalations and stringent air emission regulations. Whereas sludge
incineration appeared quite attractive when capital costs were financed
with Federal and State funds, operating expenses are now a burden for the
local taxpayer. For this reason some communities have closed their
incinerators and implemented other disposal alternatives.
Composting, of course, produces a beneficial substance which can be used
as a soil conditioner by farmers, homeowners, highway departments, and
park authorities. Initial pilot and plant scale operations with sludge
composting have been favorable. However, composting is labor intensive
and the cost-effectiveness of the operation is keyed to the market for
the resulting soil conditioner.
As noted above, landspreading and landfill ing are generally recognized as
the two types of land disposal for sludge. Landspreading is a
land-intensive disposal option and its use may be limited by the lack of
available open land areas in many developed areas. Also some sludges,
because of their chemical constituents, may not be suitable for
landspreading. For these reasons, landfilling of sludges will continue
to be a viable disposal alternative.
1-1
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1.2 Sludge Landfills and Solid Waste Disposal Facility Classification
Criteria
Sludge landfill ing generally can be defined as the burying of sludge;
i.e., the application of sludge to the land and subsequent interment by
applying a layer of cover soil atop the sludge. To be defined as a land-
fill, the thickness of the soil cover must be greater than the depth of
the plow zone. For this reason, subsurface injection of sludge is a
landspreading, not a landfill ing operation.
Classification Criteria for Solid Waste Disposal Facilities are being
promulgated by EPA. These criteria establish the minimum performance
standards that solid waste land disposal facilities shall meet so as to
be classified as posing no reasonable probability of adverse affects on
health or the environment. For all solid waste disposal facilities, the
following areas are included:
1. Environmentally sensitive areas
a. Wetlands
b. Floodplains
c. Permafrost areas
d. Critical habitats of endangered species
e. Recharge zones of sole source aquifers
2. Surface water
3. Groundwater
4. Air
5. Application on land used for the production of food chain crops
6. Disease vectors
7. Safety
a. Explosive gases
b. Toxic or asphyxiating gases
c. Fires
d. Bird hazards to aircraft
e. Uncontrolled access
1-2
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Many of the topics considered in the proposed Criteria are addressed by
State and local regulations. In some cases State and local regulations
will address concerns that are not covered by the Criteria. In all
cases, the State and local requirements should be consulted.
1.3 Objectives of Manual
The primary objective of this manual is to provide general guidance and a
source of information to be used in the planning, design, and operation
of a landfill receiving municipal wastewater treatment plant sludge.
Accordingly, typical procedures, case studies, and examples are presented
which are intended to serve as aids to the user.
Major alternative sludge landfilling methods are identified and
described. Guidance is given on the selection of the landfilling method
which is best suited for a given combination of sludge characteristics
and site conditions. For each landfilling method, the following features
are addressed: public participation program, site selection, design,
operation, monitoring, completed site, management, and costs.
1.4 Scope of Manual
The manual represents the current state-of-the-art with respect to muni-
cipal sludge landfills. Available sources of information (both in the
literature and in operating practice) were investigated and incorporated
into the manual. Where specific design criteria may seem lacking, it is
due to the limited research effort which has been performed on sludge
landfills, in comparison to other disposal options (e.g., landspreading).
The variability of regulatory requirements from state-to-state and
year-to-year would have made such design criteria difficult to compile
and easily outdated. Accordingly, design criteria and operational
procedures for existing sludge landfills were sometimes included in lieu
of prescribing these criteria and procedures for new sites. This manual
is not intended to serve as a textbook or to supplant engineering
judgement. On an actual site design, sound engineering judgement should
be exercised either to verify the design criteria (if these are included
in this manual) or initially determine the criteria (if these are not
included).
Although this manual is in general accordance with the Classification
Criteria for Solid Waste Disposal Facilties, it is not intended to define
policy on municipal sludge landfills. Further, following the design
criteria and operating procedures of this manual will not guarantee
compliance with the Criteria. However, the manual is intended to present
state-of-the-art technology and adherence of a sludge landfill to the
1-3
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principles presented in this manual will probably result in general
compliance with the Criteria. However, each landfill has a unique set of
site conditions that must be addressed individually.
This manual is directed at the disposal of sludges generated by municipal
wastewater treatment plants. Sludges generated by industrial wastewater
treatment plants are not necessarily within the scope of this manual.
However, many industrial sludges are similar in composition to municipal
sludges and may be handled similarly. Under these circumstances, this
manual may be equally useful for industrial sludge landfills. Generally,
however, if industrial sludges contain significant concentrations of
hazardous constituents, outside references, and advice should be sought
for procedures specific to the handling of such hazardous wastes.
The manual has been confined to identifying and describing three major
operational methods. The sludge-only landfill ing methods of trench and
area fill are given emphasis. Codisposal landfill ing of sludge and
refuse is also addressed.
1.5 Use of Manual
The information contained in the manual is intended for use by wastewater
authorities, public and private operators, environmental planners, and
consulting engineers. Because of the variety of user backgrounds and
needs, the manual has been organized to allow the user to locate particu-
lar information as easily as possible.
Most users have information needs in one particular phase of sludge
landfill ing. Accordingly, most of the chapters of this manual have been
established to trace the chronological development of a landfill. Other
chapters are for general information purposes. As shown in Figure 1-1,
many of the tasks outlined are concurrent. While every attempt has been
made to make each chapter self-contained, the manual is best used in its
entirety.
The following brief chapter descriptions are provided as an introduction
to the organization of the manual.
Chapter 2 - Public Participation Program
The objectives of a public participation program as well as its advan-
tages and disadvantages are discussed. The design of a public
1-4
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FIGURE 1-1
SUGGESTED TIMING OF PLANNING, DESIGN, AND OPERATION
ACTIVITIES FOR SAMPLE LANDFILL WITH FIVE YEAR LIFE
Activity
Public Participation Program
Landfilling Method Selection
Site Selection
Design
Construction
Operation
Monitoring
Year
1
2
•
-
«•
3
4
5
6
7
8
9
10
11
12
participation program including a schedule of activities and a list of
target groups for a public participation programs is included.
Chapter 3 - Sludge Characteristics and Landfill ing Methods
General information on the sources, treatment, and characteristics of
municipal sludge is presented. Major alternative sludge landfill ing
methods (and sub-methods) are defined and described. Guidance is given on
the selection of the landfill ing method best suited for a given set of
sludge characteristics and site conditions.
£hajyte_r_ 4 - Site Selection
Major criteria that affect the selection of a landfill site are identi-
fied. A general procedure for applying these criteria to a site
selection is outlined. A specific example of a site selection process
using a scoring system is introduced.
Chapter 5 - Design
Sourcesofinformation needed for designing a sludge landfill are
detailed. Methodologies for performing designs and submitting design
documents are outlined. Design features for each landfill ing method are
discussed. Environmental factors are described and appropriate control
mechanisms are detailed, including control of leachate and gas.
Chapter 6 - Operation
Operational procedures for each landfill ing method are described, in-
cluding equipment and personnel requirements. Illustrations and brief
descriptions of specific landfills demonstrating alternative landfill ing
methods are included.
1-5
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Chapter 7 - Monitoring
inapier / - Monitoring
Concepts for conducting groundwater, surface water, and gas monitoring
are presented. Sample point location, well construction, sampling
techniques, analytical methods, and data interpretation are discussed.
Chapter 8 - Completed Site
Procedures for site closure are outlined. Characteristics of a completed
sludge landfill and uses of completed sites are discussed.
Chapter 9 - Management and Costs
Management functions are discussed. Typical costs for existing sludge
landfills are presented. A comparison of costs for the various
landfill ing methods is shown.
Chapter 10 - Design Examples
Using given sludge characteristics and site conditions, design features
are outlined and operational procedures established for three sludge
landfills. These three examples cover the full range of large to small
treatment facilities.
Chapter 11 - Case Studies
Detailed descriptions of the site selection, public participation,design,
operation, and monitoring programs at five landfills are presented. In
addition, costs for the operations are discussed. Summary tables of
design, operation, and cost data for 22 sites are presented.
1-6
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CHAPTER 2
PUBLIC PARTICIPATION PROGRAM
2.1 Introduction
Traditionally, little effort has been made to involve the public in en-
gineering projects. Where exceptions exist, the emphasis has been on
developing public acceptance programs. The term "acceptance", however,
precisely conveys the kind of role the public was expected to play in
these programs—that of a passive recipient of information geared to win
general approval so that the engineer could proceed with the best pos-
sible technical design. But this type of approach will no longer work.
The public expects to play an active part in environmental decision-
making as both the Clean Water Act of 1977 (PL 95-217) and the Resource
Conservation and Recovery Act of 1976 (PL 94-580) mandate public involve-
ment mechanisms and activities. Therefore, the purpose of a public
participation program (PPP) in the establishment of sludge landfills is
to give the public a participatory role throughout planning, design, and
operation. This chapter details the objectives of a public participation
program, its advantages and disadvantages, PPP participants, the design
of a program, timing of public participation activities, and areas of
public concern in sludge landfill ing.
2.2 Objectives of a Public Participation Program
The objectives of a public participation program are:
1. Promoting full public understanding of the need for a sludge
landfill and the principles of its operation
2. Keeping the public well-informed on the status of various plan-
ning, design, and operation activities
3. Soliciting from concerned citizens their relevant opinions and
perceptions involving sludge landfill development
The key to achieving these objectives is the maintenance of continuous
two-way communication between sludge landfill planners/designers/opera-
tors and the public. A common problem for engineers and public officials
is the assumption that educational, informational, and other one-way
communication techniques provide for an adequate dialogue. When de-
signing a public participation program, sufficient mechanisms must be
provided for meaningful public input into the decision process (see
Section 2.5, Design of a PPP). It must be emphasized that a PPP will
increase the lead time required to select, design, and construct a
landfill. This fact must be considered when initially determining the
need for a new site.
2-1
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2.3 Advantages and Disadvantages of a PPP
The utility of a public participation program is not universally recog-
nized. Admittedly, there are disadvantages as well as advantages
associated with public participation in sludge landfill decision-making.
The advantages of a PPP include [1]:
1. An increased likelihood of public approval for the final plans
2. A method of providing useful information to decision-makers,
especially where values or factors that are not easily quanti-
fied are concerned
3. Assurance that all issues are fully and carefully considered
4. A safety valve in providing a forum whereby suppressed feelings
can be aired
5. Increased accountability by decision-makers
6. An effective mechanism to force decision-makers to be responsive
to issues beyond those of the immediate project
The disadvantages of a PPP include [1]:
1. A potential for confusion of the issues since many new perspec-
tives may be introduced
2. A possibility that erroneous information will be disseminated
from unknowledgeable participants
3. An added cost to the project due to public involvement
4. Possible delays in the project due to public involvement
5. A possibility that the effort will not involve the appropriate
people or that citizens will not develop an interest in the
project until it is too late for changes to be initiated
6. Public resistance to sludge landfill ing may still be high
despite the best efforts of a PPP
Despite these disadvantages, a PPP is well worth the extra cost as more
expensive project delays are probable if an irate populace becomes
involved late in the process. The benefits derived from a PPP will, in
the long-run, contribute to an effective decision-making process and
outweigh the disadvantages.
2-2
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2.4 PPP Participants
When designing a PPP, it is imperative to organize an effective publicity
campaign that will reach the appropriate people at the proper times
throughout the planning process. Special efforts should be made to in-
volve groups and individuals who, from past experience, have demonstrated
an interest in environmental affairs or those who are likely to be di-
rectly affected by the proposed sludge landfill development. Developing
a list of interested persons and organizations for formal and informal
notifications and contacts is a good way to ensure public participation.
Contacting the following groups and individuals should be part of any PPP
[1]:
1. Local elected officials
2. State and local government agencies, including planning commis-
sions, councils of government, and individual agencies
3. State and local public works personnel
4. Conservation/environmental groups
5. Business and industrial groups, including Chambers of Commerce
and selected trade and industrial associations
6. Property owners and users of proposed sites and neighboring
areas
7. Service clubs and civic organizations, including the League of
Women Voters, etc.
8. Media, including newspapers, radio, television, etc.
Depending upon the particular circumstances in each area, the following
groups can also be contacted, where appropriate:
1. State elected officials
2. Federal agencies
3. Farm organizations
4. Educational institutions, including universities, high schools,
and vocational schools
5. Professional groups and organizations
6. Other groups and organizations, possibly including various urban
groups, economic opportunity groups, political clubs and asso-
ciations, etc.
2-3
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7. Labor unions
8. Key individuals who do not express their preferences through, or
participate in, any groups or organizations
Identifying and contacting these groups is only a first step. A special
effort must be made to ensure that the particularly important people,
(such as influential individuals, people who are most likely to have
strong feelings about the site, and the media) are not only informed, but
convinced of the validity of the sludge landfill project. It is crucial
that as many of these key groups as possible support the sludge landfill
and speak out in favor of it during the public participation program.
It is important that local officials are notified about the project be-
fore the issue enters the field of public debate. Again, this approach
will allow officials to form a more objective opinion about the project
and will prepare them for inquiries from the public.
Identifying specific groups and individuals as targets for public in-
volvement efforts helps to focus time and money on the most likely
participants, to focus the objectives of the PPP, and to interpret how
well the various involvement mechanisms are working.
2.5 Design of a PPP
The PPP should be tailored to each particular situation in terms of cost
and scale. A certain minimum effort should be put into every partici-
pation program, but within a basic framework, appropriateness and flexi-
bility are the keys. For example, it makes little sense to expend the
same amount of time and dollars for a program involving a sludge landfill
site on a totally unused piece of land 25 mi (40 km) from the nearest
neighbor as compared with a site in a densely populated urban area. A
common sense approach in determining the number and frequency of public
involvement mechanisms is recommended.
There are various stages in the sludge landfill development process where
public participation is critical. In order to be most effective, a
majority of this involvement should come in the beginning of the planning
process when public input has the greatest potential for shaping the
final plan. It is important to determine the limits to public and poli-
tical acceptability. By doing so early, the public plays a constructive,
as opposed to a reactive, role in decision-making. This section will
discuss the critical planning stages where public input is particularly
important and the appropriate public participation mechanisms at each
stage.
2-4
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2,5.1 Initial Planning Stage
During the initial planning stage, the scope and scale of the entire PPP
should be established. In addition, the organization of PPP components
and the use of PPP mechanisms should be determined. This determination
should recognize the existence of two general types of PPP mechanisms:
(1) interaction techniques which promote two-way communication and (2)
educational/informational activities which represent one-way communica-
tion from officials to the public. Officials at this point may be
operating authorities, elected officials, engineering consultants, or
even public relations firms.
Initially, the major activities of this stage are mostly informational/
educational. The public should be informed of the purpose of a sludge
landfill, the need for one in their community, the general design and
operation principles, the projected final land use, potential for
creation of new jobs, etc. In addition, the rationale for selecting
sludge landfilling over alternative methods such as sludge incineration,
landspreading, or composting should be explained to the public at the
outset. As initial site investigations get underway, two-way public
involvement activities become important. The following mechanisms should
be organized during this stage [2]:
Public Officials Workshop. The purpose of this meeting is to
aquaint the concerned officials with the technical considera-
tions relevant to landfilling and to obtain input from local
officials on appropriate timing of activities and areas of
potential public concern.
Advisory Committee. The role of this group is to help organize
citizen support for the proposed plan, to act as a sounding board
in providing citizen reactions to various proposals, and to take
an active part in decision-making. The group should include
representatives of local government departments, community
organizations, private industry, and others. Consultant progress
reports can be presented during these meetings and later
pub!icized.
Mailing list. Comprehensive mailing lists are the foundation of
an information output program. They must be representative of a
a broad cross-section of groups and individuals and a constant
effort is required to expand and update them if they are to be
effective.
Liaison/contact persons. These positions should be held by
personswfioare actively involved in the landfill decision-
making process; e.g., a consulting engineer, public works
official, or other comparably informed individual. In large
municipalities it may be advantageous to hire an individual to
2-5
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handle public relations. These people are indispensable for
receiving input, answering questions, expanding mailing lists,
and generally being responsive. They ensure that logs are kept
of all questions and that issues of general concern are directed
to the appropriate people for consideration.
5. Media program. This involves organizing an effective publicity
campaign through the use of various media. The media should be
contacted as early as possible and every effort should be made
to convince them of both the need for a sludge landfill as well
as the effectiveness of such landfills before the topic becomes
an emotional issue. In this way, objective treatment of the
issue by the media is more likely. Again, the extent of this
program depends upon the particular situation. Various channels
include:
a. Newspapers. A series of informative articles on sludge
landfiITing can be timed to appear throughout the project to
sustain public interest and serve as an educational tool.
Each article or news release can also transmit hard news
such as notices of public meetings, or articles describing
events at public meetings.
b. Television. This method can be very expensive, but can also
T5everyuseful in transmitting information. However,
through careful planning, some free coverage of the project
can probably be arranged through news programs, public
service announcements, or station editorials.
c. Advertisements. Full-page newspaper advertisements could be
used to relate complex information. They can incorporate a
mailback feature to highlight citizen concerns, and solicit
participation of interested individuals.
d. Posters, brochures, or displays. These can be highly ef-
fectiveeducationaltools,especially when particularly
creative and put in high traffic areas or given wide distri-
bution.
e. Radio advertisements or informational talks. The radio can
be used to advertise events or information in much the same
way that newspapers are used.
6. Classroom educational materials. This can be an effective way
of educating school children and their parents. A more economi-
cal approach than presentations in each individual school is to
design special newsletters and brochures that can also be dis-
tributed to other audiences.
2-6
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2.5.2 Site Selection Stage
The major activities of the initial planning stage are preparatory
mechanisms for the site selection stage. The procedure for site selec-
tion generally involves a preliminary screening of numerous potential
sites after which several sites are selected for more detailed investi-
gation. These selected sites should be subjected to intense public
scrutiny. It is at this point that public participation can play a
particularly formative role in determing the final site, design and
operation procedures, etc.
The majority of public interest and involvement occurs during the site
selection stage. It is important to remember that the most vocal and
organized protests also occur during the site selection process. There-
fore, the major thrust of the PPP should come during this stage, es-
pecially in the form of two-way communication techniques. Major PPP
activities to be emphasized during this stage include:
1. Public meetings. These are an excellent mechanism for providing
public information, receiving input, and achieving one-to-one
contact between consultants, local officials, and the public.
They are normally less structured than public hearings and
therefore, more likely to result in dialogue. Generally, a
series of such meetings are held in different locations within
the planning area to provide maximum opportunity for attendance
by the public. It is a good arena for the use of audio-visual
presentations. These meetings work especially well when there
are concrete issues to be discussed, and should be timed to
coincide with particularly criticial periods in the decision-
making process. For example, the public at these meetings could
screen the site selection criteria or even rate the candidate
sites against those selected criteria. The more successful
meetings are usually a result of heavy advance work. Overcoming
public apathy can be difficult, but is critically important in
these early planning stages. Consultant contracts should
clearly specify the number of public meetings to be held because
it is often costly and time-consuming to prepare for them.
2. Workshops. Generally, these have positive results although they
are not widely used because of low turnout. Such groups usually
involve citizens being given courses of instruction by agency
staff, and then addressing specific work efforts on the basis of
such instruction. Basically workshops are an educational tool
with interaction features.
3. Radio talk-shows. Many communities have local radio talk shows
where residents can call in and voice their opinions. The con-
sultant and/or a local official could give a short presentation
on the landfill plan and then field callers' questions. This is
a good opportunity to dispel some misinformation but views of
the callers are not necessarily representative of those of the
general public.
-------
2.5.3 Selected Site and Design Stage
In this stage, the landfill site is selected and detailed site design
begins. Generally, the number of participants involved may drop off in
this stage, but the level of activity may substantially increase. No
matter how active the public has been up to this point, nearby residents
of the site are not going to be happy with the siting decision.
Participation efforts should shift to focus on this particular group.
Giving these people a role in site design will alleviate some hostility
and, in the long-run, improve the public's opinion of the proposed
operation. Appropriate activities in this stage are:
1. Tours/field trips. These are useful activities for special
interest groups, such as residents near the selected sludge
landfill site, and the press. Before the proposed landfill is
opened, a tour of an existing operational sludge landfill should
be made. This can be far more effective than countless abstract
discussions. After the proposed landfill is opened, tours can
be offered of this site to educational and other groups.
Arranging for aerial views of proposed and existing sites for
small groups by chartering a plane can be especially effective.
2. Audio-visual presentations. These can be quite useful at public
information meetings to reach people missed by the field trips.
The effectiveness of this tool depends on the quality of the
script and visuals, but again, can do a great deal towards
dispelling much of the misinformation about sludge landfills
based on past experience with improperly run sites.
3. Task forces. The purpose of these groups is to recommend design
procedures in areas of particular concern for the public. This
group could be a sub-group of the Advisory Committee or a com-
mittee made up of residents near the site. The group should
have a technical orientation in order to be most effective, but
should still represent the various interest groups.
4. Formal public hearings. Although at least one is usually
required by law, a public hearing is usually only a formality.
They tend to be structured procedures, involving prior notifica-
tion, placing of materials in depositories for citizen review
prior to the hearing, and a formal hearing agenda. The hearing
itself usually takes the form of a presentation by the consul-
tants, followed by statements from the citizens in attendance.
Questions are normally allowed, but argumentative discussion and
"debates" are discouraged because of time limitations. Sponsors
tend to prefer to adopt a "listening" posture and allow the
public to express itself without challenge. This kind of de-
tached attitude tends to generate a great deal of hostility in
the public. It conveys the message that the public is powerless
to change engineering decisions and this is precisely the type
2-8
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of message that a PPP is .supposed to dissipate. Since public
hearings are usually held in the site selection stage before
adoption of the final design plan, they provide an insufficient
means of legitimate citizen involvement in the complete plan-
ning, design, and operation decision-making process. The
responsiveness of a public hearing can be enhanced by having
elected officials chairing or at least particiating in the
process. Nevertheless, public hearings perform their proper
legal and review functions only as part of a total PPP.
2.5.4 Construction and Operation Stage
The role of the public in this stage is limited, but the actions of engi-
neers and sludge landfill operators are extremely important. It is in
this stage that the sludge landfill developers must "make good" on their
assurances of running a well-operated, well-maintained site. Public
confidence in local officials can be reinforced through the proper
handling of sludge landfill development. Otherwise, it will be extremely
difficult to establish public support for this or any future sludge
landfill.
Public involvement at this stage will most likely mainly consist of com-
plaints related to construction and operation activities. Mechanisms to
handle this interaction include:
1. Telephone line. This is a good tool to register complaints and
concerns and to answer questions. It is important that each
call is followed up with a response addressing the actions taken
to alleviate the problem.
2. Ombudsman or representative. This is an individual who has the
ear of the landfilloperators and can mediate difficulties that
may arise which the citizens feel are not being handled ade-
quately.
2.6 Timing of Public Participation Activities
Correct timing of the public participation activities is critical. In
order to be effective, the program must be diversified and sustained.
Table 2-1 lists suggested timing of PPP mechanisms for a sample 15-month
landfill project. Public hearings are formalities and, as such, occur at
the beginning and end of the planning process. Advisory Committee
meetings have the function of providing a forum for progress reports and
regular input and, therefore, are scheduled to occur from every 2 to 3
months. Public meetings are held jointly with Advisory Committee
meetings and are timed to obtain input during the critical points in
decision-making. Sufficient time is allowed after each public meeting to
give decision- makers time to react to comments and incorporate
2-9
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suggestions before final determinations are made. The various other
informational/educational activities are scheduled around the public and
advisory committee meetings in order to arouse public interest at times
when input will be the most valuable.
TABLE 2-1
SUGGESTED TIMING OF PUBLIC PARTICIPATION ACTIVITIES
FOR SAMPLE 15-MONTH PROJECT
PPP activities and mechanisms
Publ ic hearings
Publ ic meetings
Advisory Committee meetings
Mailing list development and
mai 1 i ngs
Availability of contact people
Newspaper articles
New releases
Audio-visual presentations
Newspaper advertisements
Posters, brochures, and
displays
Workshops
Radio talk-shows
Tours/field trips
Ombudsman
Task force
Telephone line
Decision stage
Initial
pi anni ng
Site selection
Design
Con-
struction
Operation
Month
T~
X
2
qp
©
®
X
X
X
3
X
X
X
4
X
b
X
X
6
X
/
X
X
8
X
X
X
X
X
y
©
00
X
10
X
X
11
X
X
X
12
®
(x)
©
X
13
X
14
X
Ib
®
®
X
X
16
17
X
joint meeting
As stated before, a great deal of time and effort is involved in a PPP.
When budget or time restrictions prohibit development of an ideal pro-
gram, it is more important to apply participation techniques that are
highly effective. Table 2-2 indicates the relative capabilities of the
suggested PPP activities.
2.7 Potential Areas of Public Concern
A PPP should serve to dispel any myths and misinformation the public may
have concerning sludge landfills. It should also address the irrever-
sible impacts of all landfill developments and other issues of concern in
the environmental impact report (see Chapter 4). The most effective
participation activities for handling these issues are the interaction
techniques (i.e., public meetings, tours/field trips, and displays that
are manned by personnel to answer questions). Some of the concerns most
likely to arise during sludge landfill development are listed in Table
2-3 along with the chapters that address these issues in the manual.
2-10
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TABLE 2-2
CAPABILITIES OF PUBLIC PARTICIPATION TECHNIQUES
Communication characteristics
Public participation technique
Public hearings
Publ ic meetings
Advisory Committee meetings
Mail ings
Contact persons
Newspaper articles
News releases
Audio-visual presentations
Newspaper advertisements
Posters, brochures, displays
Workshops
Radio talk shows
Tours/field trips
Onbudsman
Task force
Telephone line
L - low
M = medium
H = high
Level of
publ ic
contact
achi eved
M
M
L
M
L
H
H
M
H
H
L
H
L
L
L
H
Abil ity to
handle
specific
interest
L
L
H
M
H
L
L
L
L
L
H
M
H
H
H
M
Degree of
two-way
communication
L
M
H
L
H
L
L
L
L
M
H
H
H
H
H
M
TABLE 2-3
PUBLIC CONCERNS
Public concern
Manual chapter
Pre-development land uses and subsequent
environmental impacts
Zoning problems/conflicting land uses
Groundwater pollution and leachate
Gas migration
Vectors
Noise
Odor
Aesthetics - including site visibility
Safety and health
Traffic
Spillage
Sedimentation and erosion
Final land use
4 - Site Selection
4 - Site Selection
5 - Design
5 - De si g n
6 - Operation
6 - Operation
6 - Operation
6 - Operation
6 - Operation
6 - Operation
6 - Operation
6 - Operation
8 - Completed Site
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Local officials should be prepared to handle questions concerning these
issues. Obviously a majority of these problems simply do not arise with
a well-operated, efficiently-run site, and this fact should be heavily
emphasized. Also, since each situation is unique, mechanisms to ease
these concerns have to be tailored to the characteristics of each site.
Local residents and officials should be creative in solving any problems
that may arise. Above all, the attitude of local officials during
interactions with citizens is extremely important and must at all times
be open and responsive.
2.8 Conclusion
Even the best program to involve the public in sludge landfill decision-
making may not alleviate citizen dissatisfaction or anger. This criti-
cism has often been cited to justify only minimal public participation
efforts. However, active public involvement will positively contribute
to the long-term political and public acceptability of any plan, increase
public confidence in local officials, and give citizens a ready oppor-
tunity to take part in the land management decisions of their community,
A PPP is a necessary part of any sludge landfill program.
2.9 References
1. Canter, L. Environmental Impact Assessment. McGraw- Hill Book Co.,
New York, New York. 1977. pp. 221, 222.
2. CH2M Hill, Donahue and Associates, et al. Preliminary Draft:
Community Involvement Program, Metropolitan Sewerage District of the
County of Milwaukee, Water Pollution Abatement Program. December
1977. pp. A-l-A-8.
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CHAPTER 3
SLUDGE CHARACTERISTICS AND LANDFILLING METHODS
3.1 Purpose and Scope
The purpose of this chapter is to present pertinent background
information on municipal wastewater treatment sludge and to define
alternative sludge landfill ing methods. Subsequently, each landfill ing
method is described in terms of the sludge and site conditions peculiar
to that method. For a given combination of sludge and site conditions, a
single landfilling method can be selected. Thus, the landfilling method
selection (and ultimately the design) requires an accurate inventory of
the sludge characteristics. Sections 3.2, 3.3, and 3.4 in this chapter
discuss sludge sources, sludge treatment, and sludge characteristics,
respectively. Section 3.5 defines the suitability of sludge for
landfilling and Section 3.6 discusses alternative sludge landfilling
methods and relates them to suitable sludge characteristics and site
conditions.
It should be noted that the background discussion on sludge in this
chapter has been kept brief. For further information it may be advisable
to consult more detailed references on the subject. Excellent references
include "Sludge Processing, Transportation, and Disposal/Resource
Recovery: A Planning Perspective" [1], "Process Design Manual for Sludge
Treatment and Disposal" [2], and "Seminar Handout for Sludge Treatment
and Disposal" [3],
3.2 SIudge Sources
In the process of treating wastewater, solids are produced. Various
treatment processes are designed to remove specific types of solids.
3.2.1 Primary Treatment
Solids removed in primary treatment may include:
1. Screenings
2. Grit
3. Skimmings
4. Sludge
3-1
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3.2.1.1 Screenings
Screenings are solids such as rags, sticks, and trash in the raw waste-
water that are removed on racks or bar screens placed at the head of the
treatment plant. The quantity of screenings captured in a wastewater
treatment plant will vary depending upon the size of the rack or screen
openings. Screenings may be disposed of separately or ground by hammer-
mills or shredders and added to the wastewater for later removal in
sedimentation basins. Screenings typically have a moisture content of 85
to 95% and an organic content of 50 to 80% [1],
3.2.1.2 Grit
Heavy inert material or grit such as sand, silt, gravel, ashes, and cof-
fee grounds are selectively removed at the head of the wastewater treat-
ment plant, either by velocity control in simple gravity settling
chambers or by buoyant induction in air flotation tanks. Grit is often
washed after collection to reduce the concentration of organics which may
be as high as 50% of the total grit solids. The high organics are
largely responsible for the odors associated with grit.
3.2.1.3 Skimmings
Skimmings consist of floatable materials collected from sedimentation
basins. Skimmings may be subsequently digested, dewatered, incinerated,
and/or landfilled. When skimmings are unstabilized, cover may have to be
applied immediately at landfills to control odor. Treatment of skimmings
in digesters is common, however, particularly with mixed units. Vacuum
filtration dewatering normally requires prior mixing with more readily
dewaterable materials or the use of a sludge precoat on the filter.
3.2.1.4 Sludge
Sludge which accumulates in the primary clarifier varies from 2 to 8%
solids depending on the operating efficiency of the clarifier and on
whether thickening is used. The solids mass will increase if there is a
substantial amount of ground garbage. Primary sludge has a larger
particle size than that for secondary sludges. Anaerobic digestion and
the various dewatering techniques are more easily applied to the sludge
from primary clarifiers. Nevertheless, primary sludge is frequently
mixed with secondary sludge prior to treatment.
3-2
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3.2.2 Secondary Treatment
The solids from trickling filters thicken in the final clarifier to 1 to
3% by weight, the denser solids resulting from low-loaded filters. The
quantity and physical characteristics of the solids from rotating bio-
logical contactors are comparable to those from trickling filters.
Activated sludge processes use a suspension of aerobic microorganisms to
remove soluble and colloidal organic matter. These organisms can vary in
type, concentration, and degree of agglomeration depending upon the phy-
sical features of the plant, types of pollutants, and degree of pollutant
level. Sludges from these processes range from about 0.5% up to 5%
solids depending on the operating efficiency of the clarifier and on
whether the waste activated sludge is thickened.
Chemical addition to primary and secondary treatment processes increases
sludge mass (and usually volume) with the additional settled colloidal
matter and suspended solids from the wastewater and the settled chemicals
themselves. In some instances, however, sludge volumes may actually
decrease as a result of increased sludge density. Aluminum and iron
salts, lime, and organic polymers are frequently employed to enhance the
removal of colloidal material, suspended solids, and phosphorus in
primary, secondary, and tertiary processes.
3.2.3 Industrial Sources
In extreme cases, industrial influent to municipal wastewater treatment
plants can have three harmful effects. They may (1) "upset" biological
treatment processes, (2) make sludge treatment and disposal difficult, or
(3) creatf: a "pass-through" effect allowing contaminants to reach
drinking water sources. Usually, the effects are somewhat less severe
and may be limited to (1) increases in heavy metal, refractory organic,
or salt concentrations, (2) the addition of slime, or (3) higher
concentrations of granular or fibrous material. Viral and bacterial
contamination from human waste does not change significantly with
increases in industrial waste fractions. Pretreatment regulations [4]
now being promulgated by EPA should reduce or cease the harmful effects
which industrial influents can have on municipal plants.
3.3 Sludge Treatment
The basic sludge treatment processes and their function are outlined
below [2]. Thereafter, brief descriptions of the basic processes are
presented.
3-3
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Unit Processes
Thickening
Stabilization
Conditioning
Dewatering
Heat Drying and Conversion
Functions
Water removal
Volume reduction
Post process efficiencies
Blending
Pathogen destruction
Volume and weight reduction
Odor control
Putrescibil ity control
Gas production
Conversion
Improved dewatering or thickening
rate
Improved solids capture
Improved compactability
Stabilization
Water removal
Volume and weight reduction
Improve ease of handling by con-
version of liquid sludge to
damp cake
Reduced fuel requirements for
i nc i nerat i on/dryi ng
Destruction of sol ids/pathogens
Conversion
Recovery of dried sludge for use
as soil conditioner
Stabilization
3.3.1 Thickening
In sludge thickening processes, water is extracted from the sludge, thus
increasing the sludge solids content and decreasing the sludge volume.
The most common methods for thickening are by gravity, air flotation, and
centrifugation. If the sludge is to be disposed via sludge-only landfil-
ling, subsequent dewatering will be required. Sludge thickening may
provide a blending function in combining and mixing primary and secondary
sludges. Sludge thickeners are also used as flow equalization tanks to
minimize the effect of sludge quantity fluctuations on subsequent treat-
ment processes.
3-4
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3.3.2 Stabilization
3.3.2.1 Anaerobic Digestion
Anaerobic digestion is the decomposition of organic matter in the absence
of free oxygen. This decomposition is accompanied by gasification and
liquifaction which in turn lead to stabilization, colloidal ^tract'i v
breakdown, and release of moisture [5], Depending upon the initial
volatile solids content of the sludge to be treated, anaerobic digestion
can achieve a 50 to 70% reduction in volatile solids. The prim?. '
purposes of anaerobic digestion [5] are to:
1. Prevent nuisances by decomposing organic solids to a more stable
form.
2. Reduce sludge mass by converting organic solids to gases and
1iquids.
3. Reduce pathogenic organisms.
Other possible uses that anaerogic digesters have performed are:
1. Reduction of volume by concentrating the remaining solids into a
denser sludge.
2. Storage of sludge to accommodate fluctuations in wastewattt
flows and to permit flexibility in subsequent dcwatering
operations.
3. Homogenization of sludge solids to facilitate subsequent-
handling procedures.
3.3.2.2 Aerobic Digestion
Aerobic digestion, which takes place in the presence of free oxygen
produces a final material consisting of inorganics and volatile solids
that resist further biological degradation [1].
3.3.3 Conditioning
Sludge conditioning improves the dewaterability of the sludge by changing
its chemical and physical characteristics.
3-5
-------
3.3.3.1 Sludge Conditioners
The use of additives for sludge conditioning is widely applied to
increase the productivity of mechanical dewatering equipment and obtain
greater flexibility in subsequent sludge treatment and disposal
processes. Conditioning additives such as ferric chloride, lime, alum,
chlorine, organic polymers, and ash are used for coagulation of the
sludge solids and release of bound water [1], Generally, polymer treated
sludges tend to be sticky, slick, and less workable than other sludges
and frequently require special operational considerations at the
landfill. Moreover, some conditioned sludges are corrosive.
3.3.3.2 Elutriation
Elutriation, which involves mixing of digested sludge with water and
resettling, improves the dewatering characteristics of the sludge. It
also reduces the chemical conditioning requirements by reducing the
alkalinity of the sludge, thereby reducing the amount of ferric chloride
and lime required if inorganic conditioning is elected. Elutriation
should, however, be used in conjunction with polyelectrolytes to settle
the fine solids and reduce recirculation.
3.3.3.3 Heat Treatment
Heat treatment is a conditioning process that involves heating the sludge
for short periods of time under pressure. Heat treatment results in
coagulation of the sludge solids, breakdown of the gel structure of the
sludge, and reduction of the water affinity of the sludge solids. Thus,
the sludge is sterilized, and generally readily dewatered without the
addition of conditioning chemicals [1]. However, heat treatment will
solubilize organics and produce a liquid sidestream which may sometimes
cause problems. Further, although the sludge produced by heat treatment
is practically deodorized, the process itself can be quite malodorous.
3.3.4 Dewatering
There are several methods available for dewatering sludges at present.
They include vacuum filters, centrifuges, filter presses, belt presses,
lagoons, and sand drying beds. Sludge dewatering processes achieve a
degree of water removal immediately between those of thickening and
drying. Dewatered sludge solids of 15 to 40% are common with organic
sludges, and values of 45% or more can be achieved with some inorganic
sludges [6][7].
3-6
-------
3.3.4.1 Vacuum Filtration
Vacuum filtration is the most commonly used mechanical dewatering method
in the United States. With chemical conditioning, the solids capture can
produce a filter cake that ranges from 15 to 25%.
3.3.4.2 Centrifugation
Centrifugation is used in both thickening and dewatering operations and
usually in conjunction with chemical conditioning. Centrifugation can
prpduce dewatered cakes generally comparable to those obtained by vacuum
filtration [6]. Centrifugation has several advantages over vacuum
filtration; it is simple, compact, and totally enclosed (thereby reducing
odor problems in the solids handling facilities) [5]. Typically,
Centrifugation cake solids contents range from 10 to 30%, with values of
40% or more possible [7]. When Centrifugation is not done in conjunction
with chemical conditioning, solids capture can be a problem.
3.3.4.3 Pressure Filtration
Sludge dewatering by means of a filter press is a batch operation.
Sludge is pumped into the press and passes through feed holes along the
length of the filter. As the press is closed by either electrical or
hydraulic means, water is pressed out of the feed sludge and is dis-
charged through filtrate drain holes. Solids of 30 to 50% are reported
in the literature; however this figure may be misleading since solids may
be substantially increased through the addition of conditioner solids
3.3.4.4 Belt Presses
Belt presses, a relatively recent innovation, produce a broad range of
solids, depending on the design of the press and the nature of the feed.
Solids ranging from 15 to 40% may be achieved with this process [3].
3.3.4.5 Lagoons and Drying Beds
Lagoons and sand drying beds can be used to both store and dewater
sludge, although some stabilization usually occurs. With suitable lagoon
depths, retention times, and climates, sludge can be thickened to over
10% solids. Sludge solids up to 40% have been reported in the literature
for long detention times [1].
3-7
-------
3.3.5 Drying and Conversion
Sludge conversion processes are generally thermal techniques and are
intended to reduce the solids required for final disposal or to recover a
resource. Table 3-1 indicates the sludge conversion and resource
recovery processes. Obviously, the prevailing air pollution regulations
and fuel costs should be taken into account. Thus, high costs for
auxilliary fuels and air pollution controls may be incurred.
TABLE3-1
CONVERSION PROCESSES [2]
Conversion Process
Pretreatment Required
Additional Processing
Requirements
Established Processes
Incineration
Wet air oxidation
Heat drying
Experimental Processes
Pyrolysis
Incineration/
chemical recovery
Thickening and dewatering
Thickening
Thickening and dewatering
Thickening and dewatering
Thickening and dewatering
Landfill ash
Treat cooking liquor,
landfill ash
Use dried si udge as
soil conditioner
Utilize by-products of
gas, carbon, steam.
Dispose of residue
Landfill ash. Recover
lime fron recalcina-
tion or heat in power
boilers
3.3.5.1 Incineration
Combustion by incineration serves as a means of reducing total sludge
volume. End products of combustion are usually water, carbon dioxide,
sulfur dioxide, and inert ash [6]. The characteristics of ash vary
according to the sludge incinerated. Table 3-2 summarizes the content of
ash from four treatment plants. A significant portion of the ash can be
used as a sludge conditioner. The remaining ash may be landfilled, but
it should be noted that the heavy metal content is, of course, higher
than sludges and consequently a lower loading rate is advisable.
3-8
-------
TABLE 3-2
COMPOSITION OF VARIOUS ASHES (%) [8]
Element
Mi 11 creek
Beckjord
Tahoe
Kansas City
Zinc
Cadmium
Arsenic
Boron
Phosphorus
Iron
Molybdenum
Manganese
Aluminum
Beryl 1 lum
Copper
Silver
Nickel
Cobalt
Lead
Chromium
Vanadium
Barium
Strontium
Calcium
Silicon
Magnesium
Other
0.56
0.07
0.33
0,26
0.33
3.33
0.13
0.03
6.99
0.001
0.03
0.01
0.07
0.07
0.13
0.23
0.13
0.26
0.01
8.46
22.00
1.00
55.57
0.10
0.10
0.50
0.05
0.50
5.30
0.20
0.05
9.40
0.001
0.07
0.01
0.10
0.10
0.20
0.05
0.20
0.01
0.01
1.5
19.17
0.45
61.93
0.11
0.10
0.50
0.05
2.70
0.97
0.20
0.05
0.29
0.001
0.05
0.01
0.10
0.10
0.20
0.14
0.20
0.03
0.01
21.13
11.15
1.30
60.61
0.13
0.10
0.50
0.18
0.50
2.65
0.20
0.05
4.6
0.001
0.05
0.01
0.10
0.10
0.20
0.10
0.20
0.08
0.01
6.18
26.96
0.51
56.59
3.3.5.2 Wet Air Oxidation
Wet air oxidation involves burning of organic matter in the absence of
flame and in the presence of liquid water. Temperatures and pressures on
the order of 400 to 600°F (150 to 225°C) and 1200 to 1800 psig (8.3 x
lO^ to 1.2 x 10^ N/cm^) are used for complete oxidation of organics
[6]. Because it is not necessary to supply energy for the latent heat of
vaporization of water, wet air oxidation is particularly applicable for
materials like organic sludges which are combustible but cannot be
readily separated from water. A problem with ash disposal in the wet air
oxidation process is that the ash is conveyed in a significant volume of
water.
3.3.5.3 Heat Drying
Heat (flash) drying is the instantaneous removal of moisture from sludge
solids by introducing them into a hot gas stream. Wet sludge from a
dewatering process is mixed with previously dried sludge, pulverized, and
introduced into the dryer. Drying by the hot gases from the furnace is
essentially complete, with the sludge having solids contents in excess of
90%. Initially, dried sludge is separated from the spent gases in a
cyclone. Subsequently, it may be (1) mixed with wet sludge from the
dewatering process, (2) stored for use as soil conditioner, (3) incin-
erated, or (4) handled in other ways.
3-9
-------
3.3.5.4 Pyrolysis
Pyrolysis is defined as the gasification and/or liquefaction of the
combustible elements in sludge by heat in the total absence of oxygen.
Most of the combustion process is carried out within a closed reactor
chamber, normally at temperatures lower than in incinerators. End
products of the process are gases, pyroligneous acids and tars, and char.
Generally, part of the solids may be used as a fuel and part can be used
as a filter aid. The remaining solids must be disposed. Most so-called
pyrolysis systems on-line today are actually partial pyrolysis or starved
air combustion. Partial pyrolysis uses less than the stoichiometric air
requirements but does allow some oxygen to enter the system.
3.3.5.5 Lime Recalcination
The process of recalcining involves incinerating the dewatered sludge
containing calcium which drives off water, organics, and carbon dioxide
and leaves calcium oxide (quicklime). After coagulating raw wastewaters,
the inert solid fraction can be removed before recalcination using a wet
centrifugation classification system. This inert solid removal must
occur to prevent solids buildup within the wastewater treatment process.
3.4 Sludge Characteristics
The following characteristics of sludge are discussed in this section:
1. Sol ids content
2. Solids characteristics
3. Pathogens
4. Heavy metals
5. Nitrogen
3.4.1 Solids Content
The solids content of sludge is dependent on its respective treatment
source (i.e., primary, secondary, etc.) and on the various sludge treat-
ment processes (stabilization, dewatering, etc.). The efficiency of
various dewatering processes for increasing the solids content is
critical. For example, if a vacuum filtration unit designed to produce
sludge with 25% solids, instead produced sludge with a solids content
ranging from 15 to 20%, severe operational problems could occur at the
3-10
-------
landfill
landfill
occur.
Only by incorporating flexibility into the design of the
can a site handle the variations in sludge that may commonly
3.4.2 Solids Characteristics
The reaction of the macroscopic and microscopic particles in sludge is a
function of (1) particle size and distribution, (2) particle configura-
tion, (3) density and (4) other factors such as the microorganisms or
free radicals present. Particle size and distribution and configuration
of individual particles are dependent upon the sources of sludge.
Particles may take on a fibrous, spherical, helical, planar, or cubic
configuration. Particle characteristics impact on sludge stability and
consistency.
Solids may be further classified as volatile or non-volatile. Volatile
solids are a measure of the amount of organic matter present in the solid
fraction of sludge. The organic matter may be ultimately broken down by
bacteria, producing methane gas via anaerobic digestion or other
chemical, physical, or biological processes. Table 3-3 outlines typical
values for volatile solids content and other parameters for raw and
anaerobically digested primary sludge.
TABLE 3-3
TYPICAL COMPOSITION OF RAW AND ANAEROBICALLY DIGESTED
PRIMARY SLUDGES [9]
Item
Total dry solids (TS), %
Volatile sol ids (% of TS)
Grease of fats (ether soluble,
% of TS)
Protein (X of TS)
Nitrogen (N, % of TS)
Phosphorus (PjOB, % of TS)
Potash (K2o, % of TS)
Cellulose (% of TS)
Iron (not as sulfide)
Silica (SlOo, % of TS)
pH
Alkalinity (mg/1 as CaCOj)
Organic acids (mg/1 as HAc)
Thermal content (BTU/lb)
Raw Primary
Range
2-7
60-80
6-30
20-30
K5-4
0.8-2.8
0-1
8-15
2-4
15-20
5-8
500-1,500
200-2,000
6,800-10,000
Sludge
Typical
4
65
—
25
2.5
1.6
0.4
10
2.5
—
6
600
500
7,600a
Anaerobical ly
Digested
Primary Sludge
Range Typical
6-20 10
30-60 40
5-20
15-20 18
1.6-6 3
1.5-4 2.5
0-3 1
8-15 10
3-8 4
10-20
6.7-7.5 7
2,000-3,500 3,000
100-600 200
2,700-6,800 4,000°
Note: — means data not shown in reference cited.
1 BTU/lb = 0.556 cal/kg
a Based on 65% volatile matter
b Based on 40X volatile matter
3-11
-------
The volume of sludge produced at a treatment facility is dependent upon
the influent wastewater characteristics, the efficiency of the processes
to reduce pollutants, and the type of sludge treatment process. For
example, dewatering processes reduce sludge volumes by removing water,
thus reducing the overall weight of the sludge. Table 3-4 outlines the
quantities of sludge produced from various treatment processes.
The addition of polymers to sludges will create a more viscous, sticky,
slippery material that can cause handling difficulties. If polymers have
been added to the sludge, a higher solids content may be required for
a specific landfill ing method.
3.4.3 Pathogens
Most sludge treatment processes significantly reduce the number of patho-
gens and decrease the chances for pathogenic contamination. Current
research indicates that undigested sludge stabilized with lime to a final
pH between 10 and 11 disposed in narrow trenches is not thought to pose a
serious hazard [9][10], Earlier works produced similar results; fecal
coliforms and pathogenic salmonella bacteria were not detected more than
a few in. (cm) into soils outside of entrenched sludges at any time
during a two-year period following entrenchment [11].
3.4.4 Heavy Metals
One of the largest contributors of heavy metals to municipal wastewater
treatment plants has been industry. Most heavy metals in wastewater are
removed by conventional treatment processes and concentrated in the
sludge. Treatment plants should analyze their sludges to determine the
concentrations of heavy metals. Typical concentrations of heavy metals
and other constituents in raw and digested municipal wastewater sludge
are listed in Table 3-5.
The movement of heavy metals through the soil is enhanced by acidic
conditions. For this reason, lime (CaO) is added to sludge prior to
dewatering to raise pH levels to 10 or 11 [12]. Generally, metals did
not leach from entrenched sludge into soils as long as the pH remained
near neutral [9][10]. On the other hand, for entrenched, unlimed
sludges, the soil and sludge became acidic due to the formation of
nitrates and sulfates, and the extent of heavy metal movement increased
C113C13].
3-12
-------
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-------
TABLE 3-5
CHEMICAL COMPOSITION OF MUNICIPAL WASTEWATER SLUDGES3 [14]
Component Units
Total N tb
NH4-N
NO,-N
P J
K
Cd
Mg
Fe
Mn mg/kgb
B
Hg
Cu
Zn
Nl
Pb
Cd
Number ot
samples Range
191
103
45
189
192
193
189
165
143
109
78
205
208
165
189
189
0.1-17.6
0.1- 6.8
0.1- 0.5
0.1-14.3
0.1- 2.6
0.1-25.0
0.1- 2.0
0.1-15.3
18-7,100
4-760
0.5-10,600
84-10,400
101-27,800
2- 3,520
13-19,700
3- 3,410
Median
3.3
0.1
0.1
2.3
0.3
3.9
0.5
1.1
260
33
5
850
1,740
82
500
16
Coefficient of
Mean variability, %c
3.9
0.7
0.1
2.5
0.4
4.9
0.5
1.3
380
77
733
1,210
2,790
320
1,360
110
85
171
158
61
99
87
75
148
209
162
232
138
134
162
177
157
a Data are from numerous types of sludges (anaerobic, aerobic, activated, lagoon,
etc.) in seven states: Wisconsin, Michigan, New Hampshire, New Jersey, Illinois,
Minnesota, Ohio
b Percent or mg/kg oven-dry solids basis.
c Standard deviation as a percentage of mean. Number of samples on which this is
based may not be the same as for other columns.
3.4.5 Nitrogen
The nitrogen species in sludge represents a source of groundwater
pollution [11]. Due to the many mechanisms associated with nitrogen
movement, it is difficult to predict the risk of pollution. The
potential for groundwater pollution is significantly affected by the
total quantity of nitrogen present and the species, which include
nitrogen, ammonia, nitrate, and nitrite. Generally, nitrate is the
principal species of concern and is relatively mobile in most soil types.
Aerobic conditions facilitate microbial conversion of other nitrogen
species to nitrate, and thus, increase the possibility for nitrogen
movement. Therefore, disposal methods providing anaerobic conditions
inhibit nitrogen movement and allow microbial destruction of pathogens
[11].
3.5 Suitability of Sludge for Landfill ing
In determining the suitability of sludge for landfill ing, a determination
should be made of the sludge sources and treatment. Analyses should also
3-14
-------
be performed on the sludge to determine relevant characteristics. This
information is needed in order that a full assessment can be made of its
suitability for landfill ing. Not all wastewater treatment sludges are
suitable for landfill ing due to either odor or operational problems. An
assessment of the suitability of various sludge types has been included
as Table 3-6.
As shown, only dewatered sludges (having solids contents greater than or
equal to 15%) are suitable for disposal in sludge-only landfills.
Sludges having solids contents less than 15% usually will not support
cover material. Obviously, the addition of soil to a low-solids sludge
may act as a bulking agent and produce a sludge suitable for disposal at
sludge-only landfills. However, soil bulking operations are generally
not cost-effective on sludges with solids less than 15%. Further
dewatering should be performed at the treatment plant if sludge-only
landfilling is the disposal option selected. Low-solids sludge (having
solids contents as low as 3%) are suitable for codisposal landfilling.
However, sludge moisture should not exceed the absorptive capacity of
refuse at a codisposal landfill. Accordingly, low-solids sludge should
be received at such sites only if it constitutes a small percentage of
the total waste landfilled.
Generally, only stabilized sludges are recommended for landfilling and
some degree of stabilization should occur if landfilling is the selected
disposal option. However, since stabilization is not required in all
states, suggested procedures for landfilling such sludges are described.
The following section describes handling and operating practices for
typical sludges. Sludge ash as well as other wastewater treatment plant
solids such as screenings, grit, and skimmings are disposed essentially
in the same manner. Specific handling of these wastes is described in
Chapter 6, Operation.
3.6 Sludge Landfilling Methods
The purpose of this section is to identify and describe several alterna-
tive methods and sub-methods for sludge landfilling. These include:
1. Sludge-only trench
a. Narrow trench
b. Wide trench
2. Sludge-only area fill
a. Area fill mound
b. Area fill layer
c. Diked containment
3-15
-------
TABLE 3-6
SUITABILITY OF SLUDGES FOR LANDFILLING
Process
Thickening
Gravity
Flotation
Treatment
Aerobic
digestion
Anaerobic
digestion
Incineration
Wet oxidation
Heat
Lime
stabil ization
Dewatering
Drying beds
Vacuum filter
Pressure
filtration
Centrifugation
Heat drying
Feed
Primary
WAS
Primary and WAS
Digested primary
Digested primary and WAS
Primary and WAS
WAS with chemical s
WAS without chemicals
Primary, thickened
Primary and WAS, thickened
Primary, thickened
Primary and WAS thickened
Primary, dewatered
Primary and WAS, dewatered
Primary or primary and WAS
Any, thickened
Primary, thickened
Primary and WAS, thickened
Any, digested
Any, lime stabilization
Primary, lime conditioned
Digested, lime conditioned
Digested, lime conditioned
Digested
Digested, lime conditioned
Digested
SI udge-only
landf illing
Suitability Reason
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
S
S
NS
NS
NS
NS
S
S
S
S
s
s
s
s
OD, OP
OD, OP
OD, OP
OP
OP
OD, OP
OP
OD, OP
OP
OP
OP
OP
—
00, OP
OD.OP
OP
OP
—
--
--
—
—
Codisposal
landf il 1 ing
Suitability Reason
NS
NS
NS
MS
MS
NS
NS
NS
MS
MS
MS
MS
S
S
MS
MS
MS
MS
S
S
s
s
s
s
s
s
OD,
OD,
OD,
OP
OP
OD,
OD,
OD,
OP
OP
OP
OP
--
OD,
OD,
OP
OP
--
—
--
--
__
OP
OP
OP
OP
OP
OP
OP
OP
WAS = Waste Activated Sludge
NS = Not Suitable
MS = Marginally Suitable
S - Suitable
OD = Odor Problems
OP = Operational Problems
3-16
-------
3. Codisposal
a. SIudge/refuse mixture
b. SIudge/soil mixture
The above-listed alternatives were found to be an appropriate classifica-
tion of major sludge landfill ing methods. Other methods were considered
and some do exist in practice. However, these other methods either (1)
did not afford sufficient protection of the environment, (2) were not
practical, or (3) were similar in many aspects to the methods listed
above.
In this section, each method is defined and subsequently described in
terms of sludge and site conditions specific to that method. In
addition, design criteria are identified for each method. The criteria
suggested for each method are based on experiences at numerous sludge
landfills which embrace a broad range of sludge and site conditions.
These criteria should be valid for the majority of sludge landfill
applications. However, design criteria should be qualified as being
"typical" or "recommended". Variations are employed and may be
appropriate in some cases. For example, the range of sludge solids
contents recommended for each method in this section may vary somewhat
depending on the sludge source, treatment, and characteristics.
Specifically, a sludge treated with polymers is more slippery and less
stable; consequently it will require a higher solids content to be
landfilled in the same manner as a sludge not treated with polymers.
Nevertheless, the criteria suggested by this section can serve as a
starting point. It is recommended that field tests be performed to
ensure that an operation based on the criteria in this section will
function properly for a given sludge and site.
3.6.1 Sludge-Only Trench
For sludge-only trenches, subsurface excavation is required so that
sludge can be placed entirely below the original ground surface. Trench
applications require that groundwater and bedrock be sufficiently deep so
as to allow excavation and still maintain sufficient buffer soils between
the bottom of sludge deposits and the top of groundwater or bedrock.
In trench applications, soil is used only for cover and is not used as a
sludge bulking agent. The sludge is usually dumped directly into the
trench from haul vehicles. On-site equipment is normally used only for
trench excavation and cover application; it is not normally used to haul,
push, layer, mound, or otherwise come into contact with the sludge.
3-17
-------
Although in some cases cover application may be less frequent, cover is
normally applied over sludge the same day that it is received. Because
of the frequency of cover, odor control is optimized; therefore, trenches
are more appropriate for unstabilized or low-stabilized sludges than
other landfill ing methods. The soil excavated during trench construction
provides quantities which are almost always sufficient for cover
applications. Accordingly, soil importation is seldom required in trench
applications.
Two sub-methods have been identified under trench applications. These
include (1) narrow trench and (Z) wide trench. Narrow trenches are
defined as having widths less than 10 ft (3.0 m); wide trenches are
defined as having widths greater than 10 ft (3.0 m). The depth and
length of both narrow and wide trenches are variable and dependent upon a
number of factors. Trench depth is a function of (1) depth to
groundwater and bedrock, (2) sidewall stability, and (3) equipment
limitations. Trench length is virtually unlimited, but inevitably
dependent upon property boundaries and other site conditions. In
addition, trench length may be limited by the need to discontinue the
trench for a short distance or place a dike within the trench to contain
a low-solids sludge and prevent it from flowing throughout the trench.
3.6.1.1 Narrow Trench
As stated previously, a narrow trench has a width of less than 10 ft (3.0
m). Sludge is usually disposed in a single application and a single
layer of cover soil is applied atop this sludge. Narrow trenches are
usually excavated by equipment based on solid ground adjacent to the
trench and equipment does not enter the excavation. Accordingly,
backhoes, excavators, and trenching machines are particularly useful in
narrow trench operations. Excavated material is usually immediately
applied as cover over an adjacent sludge-filled trench. However,
occasionally, it is stockpiled alongside the trench from which it was
excavated for subsequent application as cover over that trench. Cover
material is then applied by equipment also based on solid ground outside
of the trench. Relevant sludge and site conditions as well as design
criteria are presented in the following tabulation.
Sludge and Site Conditions
Sludge solids content - 15-20% for 2-3 ft (0.6-0.9 m) widths
- 20-28% for 3-10 ft (0.9-3.0 m) widths
Sludge characteristics - unstabilized or stabilized
Hydrogeology - deep groundwater and bedrock
Ground slopes - <20%
3-18
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Design Criteria
Trench width - 2-10 ft (0.6-3.0 m)
Bulking required - no
Cover soil required - yes
Cover soil thickness - 3-4 ft (0.9-1.2 m)
Imported soil required - no
Sludge application - 1,200-5,600 yd3/acre
rate (2,300-10,600 rrrYha)
Equipment - backhoe with loader, excavator,
trenching machine
The main advantage of a narrow trench is its ability to handle sludge
with a relatively low solids content. As shown above, a 2 to 3 ft (0.6
to 0.9 m) width is required for sludge with a solids content between 15
and 20%. Normally, soil applied as cover over sludge of such low solids
would sink to the bottom of the sludge. However, because of the narrow-
ness of the trench, the soil cover bridges over the sludge, receiving
support from solid ground on either side of the trench. In this opera-
tion cover is usually applied in a 2 to 3 ft (0.6 to 0.9 m) thickness.
A 3 to 10 ft (0.9 to 3.0 m) width is more appropriate for sludge with
solids contents from 20 to 28%. At this width, the bridging effect of
the never soil is non-existent. However, the solids content is high
enough to support cover. In this operation, cover is usually applied in
a 3 to n ft (0.9 to 1.2 m) thickness and dropped from a minimum height to
minimize the amount of soil that sinks into sludge deposits.
The main disadvantage of narrow trench operations is that it is rela-
tively land-intensive. As shown above, typical sludge application rates
in actual fill areas (including inter-trench areas) range from 1,200 to
5,600 yd3/acre (2,300 to 10,600 m3/ha). Generally, application rates
for narrow trenches are less than for other methods. Another drawback
with narrow trench operations is that liners are impractical to install.
3.6.1.2 Wide Trench
As stated previously, a wide trench has a width of greater than 10 ft
(3.0 m). Wide trenches are usually excavated by equipment operating
3-19
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inside the trench. Accordingly, track loaders, draglines, scrapers, and
track dozers are particularly useful in wide trench operations.
Excavated material is usually stockpiled on solid ground adjacent to the
trench from which it was excavated for subsequent application as cover
over that trench. However, occasionally it is immediately applied as
cover over an adjacent si udge-filled trench. Relevant sludge and site
conditions as well as design criteria are presented in the following
tabulation.
Sludge and Site Conditions
Sludge solids content - 20-28% for land-based equipment
- >28% for sludge-based equipment
Sludge characteristics - unstabilized or stabilized
Hydrogeology - deep groundwater and bedrock
Ground slopes - <10%
Design Criteria
Trench width - >10 ft (3.0 m)
Bulking required - no
Cover soil required - yes
Cover soil thickness - 3-4 ft (0.9-1.2 m) for land-based
equipment
- 4-5 ft (1.2-1.5 m) for sludge-based
equipment
Imported soil required - no
Sludge application - 3,200-14,500 yd3/acre
(6,000-27,400 irrYha)
Equipment - track loader, dragline, scraper,
track dozer
As shown above, cover material may be applied to wide trenches in either
of two different ways. If its solids content is from 20 to 28%, the
sludge in the trench is incapable of supporting equipment. Therefore,
cover should be applied in a 3 to 4 ft (0.9 to 1.2 m) thickness by
equipment based on solid undisturbed ground adjacent to the trench. In
3-20
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this way, a wide trench may be only slightly more than 10 ft (3.0 m) wide
(if a front-end loader is used to apply cover) or up to 50 ft (15 m) wide
(if a dragline is used to apply cover). Alternatively, if its solids
content is 28% or more covered sludge in the trench is capable of
supporting equipment. Therefore, cover should be applied by equipment
which proceeds out over the sludge pushing a 4 to 5 ft (1.2 to 1.5 rr<)
thickness of cover before it. Track dozers are the most useful piece of
equipment in this application.
As for narrow trenches, wide trenches should be oriented parallel to one
another to minimize inter-trench areas. Distances between trenches
should be only large enough so as to provide sidewall stability as well
as adequate space for soil stockpiles, operating equipment, and haul
vehicles.
One advantage of a wide trench is that it is less land-intensive than
narrow trenches. Typical sludge application rates range from 3,200 to
14,500 yd3/acre (6,000 to 27,400 nr/ha). Another advantage of a wide
trench is that liners can be installed to contain sludge moisture and
protect the groundwater. Therefore, excavation may proceed closer to
bedrock or groundwater in wide trenches with liners than in narrow
trenches without such protection.
One disadvantage of a wide trench is a need for a higher solids sludge,
with solids contents at 20% and above. It should be noted that sludges
with a solids content of 32% or more will not spread out evenly in a
trench when dumped from atop the trench sidewall. If wide trenches are
used for such high solids sludge, haul vehicles should enter the trench
and dump the sludge directly onto the trench floor. Another disavantage
of a wide trench is its need for flatter terrain than that used for
narrow trenches. For wide trench applications with sludge less than 32%
solids, sludge is dumped from above and spreads out evenly within the
trench. Accordingly, the trench floor should be nearly level, and this
can be more easily effected when located in low relief areas.
3.6.2 Sludge-Only Area Fill
For sludge-only area fills, sludge is usually placed above the original
ground surface. Because excavation is not required and sludge is not
placed below the surface, area fill applications are particularly useful
in areas with shallow groundwater or bedrock. The solids content of
sludge as received is not necessarily limited. However, because the
sidewall containment (available in a trench) is lacking and equipment
must be supported atop the sludge in most area fills, sludge stability
and bearing capacity must be relatively good. To achieve these quali-
ties, soil is usually mixed with the sludge as a bulking agent. Since
3-21
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excavation is not usually performed in the landfill ing area, and since
shallow groundwater or bedrock may prevail, the large quantities of soil
required usually must be imported from off-site or hauled from other
locations on-site.
Because filling proceeds above the ground surface, liners can be more
readily installed at area fill operations than at trench operations. Of
course, because of the likely proximity of groundwater or bedrock to the
ground surface, the installation of a liner will often be required at
area fills. With or without liners, surface runoff of moisture from the
sludge and contaminated rainwater should be expected in greater quanti-
ties at area fills, and appropriate surface drainage control facilities
should be considered.
In area fills, the landfill ing area usually consists of several consecu-
tive lifts or applications of sludge/soil mixture and cover soil. As for
any landfill, cover should be applied atop all sludge applications. How-
ever, this cover often is applied as necessary to provide stability for
additional lifts. Because some time may lapse between consecutive sludge
applications, daily cover is usually not provided and stabilized sludges
are better suited for area filling than are unstabilized sludges.
Three sub-methods have been identified under area fill applications.
These include (1) area fill mound, (2) area fill layer, and (3) diked
containment. Each of these three sub-methods are described subse-
quently.
3.6.2.1 Area Fill Mound
In area fill mound applications, it is recommended that the solids con-
tent of sludge received at the site be no lower than 20%. Sludge is
mixed with a soil bulking agent to produce a mixture which is more stable
and has greater bearing capacity. As shown below, appropriate bulking
ratios may vary between 0.5 and 2 parts soil for each part of sludge.
The exact ratio employed will depend on the solids content of the sludge
as received and the need for mound stability and bearing capacity (as
dictated by the number of lifts and equipment weight).
The sludge/soil mixing process is usually performed at one location and
the mixture hauled to the filling area. At the filling area, the sludge/
soil mixture is stacked into mounds approximately 6 ft (1.8 m) high.
Cover material is then applied atop these mounds in a minimum 3 ft (0.9
m) thick application. This cover thickness may be increased to 5 ft (1.5
m) if additional mounds are applied atop the first lift. Relevant sludge
and site conditions as well as design criteria are presented in the
following tabulation.
3-22
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Sludge and Site Conditions
Sludge solids content - X?0%
Sludge characteristics - stabilized
Hydrogeology - shallow groundwater or bedrock
possible
Ground slopes - suitable for steep terrain as long as
an area is prepared for mounding
Design Criteria
Bulking required -yes
Bulking agent - soil
Bulking ratio - 0.5-2 soil:l sludge
Cover soil required - yes
Cover soil thickness - 3 ft (0.9 m) of interim
- 1 ft (0.3 m) of final
Imported soil required - yes
Sludge application - 3,000-14,000 yd3/acre
(5,700-34,600 m3/ha)
Equipment - track loader, backhoe with loader,
track dozer
Because equiment may pass atop the sludge in performing mixing, mounding,
and covering operations, lightweight equipment with swamp pad tracks is
generally recommended for area fill mound operations. However, heavier
wheel equipment may be more appropriate in transporting bulking material
to and from soil stockpiles.
An advantage of the area fill mound operation is its good land utiliza-
tion. Sludge application rates are relatively high at 3,000 to 14,000
yd3/acre (5,700 to 26,400 m^/ha). A disadvantage is the constant
need to push and stack slumping mounds. For this reason, area fill
mounds often have higher manpower and equipment requirements. Some
slumping is inevitable and occurs particularly in high rainfall areas
due to moisture additions to the sludge. Slumping can sometimes be
3-23
-------
minimized by providing earthen containment of mounds where possible. For
example, area fill mound operations are usually conducted on level ground
to prevent mounds from flowing downhill. However, if a steeply sloping
site is selected, a level mounding area could be prepared into the slope
and a sidewall created for containment of mounds on one side.
3.6.2.2 Area Fill Layer
In area fill layer applications, sludge received at the site may be as
low as 15% solids. Sludge is mixed with a soil bulking agent to produce
a mixture which is more stable and has greater bearing capacity. Typical
bulking ratios range from 0.25 to 1 part soil for each part sludge. As
for area fill mounds, the ratio will depend on the solids content of the
sludge as received and the need for layer stability and bearing capacity
(as dictated by the number of layers and the equipment weight).
This mixing process may occur either at a separate sludge dumping and
mixing area or in the filling area. After mixing the sludge with soil,
the mixture is spread evenly in layers from 0.5 to 3 ft (0.15 to 0.9 m)
thick. This layering usually continues for a number of applications.
Interim cover between consecutive layers may be applied in 0.5 to 1 ft
(0.15 to 0.3 m) thick applications. Final cover should be from 2 to 4 ft
(0.6 to 1.2 m) thick. Relevant sludge and site conditions as well as
design criteria are presented in the following tabulation.
Sludge and Site Conditions
Sludge solids content - XI5%
Sludge characteristics - stabilized
Hydrogeology - shallow groundwater or bedrock
possible
Ground slopes - suitable for medium slopes but level
ground preferred
Design Criteria
Bulking required -yes
Bulking agent - soil
Bulking ratio - 0.25-1 soilrl sludge
3-24
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Cover soil required - yes
Cover soil thickness - 0.5-1 ft (0.15-0.3 m) of interim
- 2-4 ft (0.6-1.2 m)
Imported soil required - yes
Sludge application - 2,000-9,000 yd3/acre
(3,800-17,000 mj/ha)
Equipment - track dozer, grader, track loader
As for mounding operations, equipment will also pass atop sludge in
performing mixing, layering, and covering functions. Accordingly,
lightweight equipment with swamp pad tracks is generally recommended for
area fill layer operations. However, heavier wheel equipment may be
appropriate for hauling soil. Slopes in layering areas should be
relatively flat to prevent the sludge from flowing downhill. However, if
the sludge solids content is high and/or sufficient bulking soil is used,
this effect can be prevented and layering performed on mildly sloping
terrain.
An advantage of an area fill layer operation is that completed fill areas
are relatively stable. As a result, the maintenance required is not as
extensive as for area fill mounds. Accordingly, manpower and equipment
requirements are less. A disadvantage is poor land utilization with
application rates from 2,000 to 9,000 yd^/acre (3,780 to 17,000
irrYha).
3.6.2.3 Diked Containment
In diked containment applications, sludge is placed entirely above the
original ground surface. Dikes are constructed on level ground around
all four sides of a containment area. Alternatively, the containment
area may be placed at the toe of a hill so that the steep slope can be
utilized as containment on one or two sides. Dikes would then be
constructed around the remaining sides.
Access is provided to the top of the dikes so that haul vehicles can dump
sludge directly into the containment. Interim cover may be applied at
certain points during the filling, and final cover should be applied when
filling is discontinued. Relevant sludge and site conditions as well as
design criteria are presented in the following tabulation.
3-25
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Sludge and Site Conditions
Sludge sol ids content
Sludge characteristics
Hydrogeology
Ground slopes
- 20-28% for land-based equipment
- >28% for sludge-based equipment
- unstabilized or stabilized
- shallow groundwater or bedrock
possible
- suitable for steep terrain as long as
a level area is prepared inside
dikes
Design Criteria
Bulking required
Bulking agent
Bulking ratio
Cover soil required
Cover soil thickness
Imported soil required
Sludge application
Equipment
- no, but sometimes used
- soil
- 0.25-1 soil :1 sludge
- yes
- 1-2 ft (0.3-0.6 m) of interim with
land-based equipment
- 2-3 ft (0.6-0.9 m) of interim with
sludge-based equipment
- 3-4 ft (0.9-1.2 m) of final with
land-based equipment
- 4-5 ft (1.2-1.5 m) of final with
sludge-based equipment
- yes
- 4,800-15,000 yd3/acre
(9,100-28,400 rrrYha)
- dragline, track dozer, scraper
As shown above, the solids content of sludge received at diked contain-
ments should be a minimum of 20%. For sludges with solids contents
between 20 and 28%, cover material should be applied by equipment based
on solid ground atop the dikes. For this situation, a dragline is the
best equipment for cover application due to its long reach. Thicknesses
should be 1 to 2 ft (0.3 to 0.6 m) for interim cover and 3 to 4 ft (0.9
to 1.2 m) for final cover.
3-26
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For sludges with solids contents of 28% and above, cover material should
be applied by equipment which pushes and spreads cover soil into place as
it proceeds put over the sludge. For this situation, a track dozer is
the best equipment for cover application. Thicknesses should be 2 to 3
ft (0.6 to 0.9 m) for interim cover and 4 to 5 ft (1.2 to 1.5 m) for
final cover.
Usually diked containment operations are conducted without the addition
of soil bulking agents. Occasionally, however, soil bulking is added.
Under these circumstances, soil may be added to increase the solids
content and allow the operations described above.
An advantage of this method is that individual diked containments are
relatively large with typical dimensions of 50 to 100 ft (15 to 30 m)
wide, 100 to 200 ft (30 to 60 ft) long, and 10 to 30 ft (3 to 9 m) deep.
Accordingly, efficient land use is .realized with sludge loadjng rates
varying between 4,800 and 15,000 yd^/acre (9,100 to 28,400 nf/ha). A
disadvantage of diked containment is that the depth of the fill in con-
junction with the weight of interim and final cover, places a significant
surcharge on the sludge. As a result, much of the sludge moisture is
squeezed into surrounding dikes and into the floor of the containment.
Accordingly, liners and other leachate controls may be especially
appropriate with diked containments to collect leachate emissions.
3.6.3 Codisposal
A codisposal operation is defined as the receipt of sludge at a refuse
landfill. Two sub-methods have been identified under codisposal opera-
tions. These include (1) sludge/refuse mixture and (2) sludge/soil
mixture.
3.6.3.1 Sludge/Refuse Mixture
In a sludge/refuse mixture operation, sludge is deposited at the working
face of the landfill and applied atop refuse. The sludge and refuse are
then mixed as thoroughly as possible. This mixture is then spread, com-
pacted, and covered in the usual manner at a refuse landfill. Relevant
sludge and site conditions as well as design criteria are presented in
the following tabulation.
3-27
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Sludge and Site Conditions
Sludge solids content
Sludge characteristics
Hydrogeology
Ground slopes
- unstabilized or stabilized
- deep or shallow groundwater or
bedrock
- <30%
Design Criteria
Bulking required
Bulking agent
Bulking ratio
Cover soil required
Cover soil thickness
Imported soil required
Sludge application
Equipment
- yes
- refuse
- 4-7 tons refuse:! wet ton sludge
- yes
- 0.5-1 ft (0.15-0.3 m) of interim
- 2 ft (0.6 m) of final
- no
- 500-4,200 ydVacre
(900-7,900 m3/ha)
- track dozer, track loader
As shown above, sludge with solids contents as low as 3% may be received
in such operations. Usually, such sludge is spray applied from a tank
truck to a layer of refuse at the working face. The bulking ratio for a
3% solids sludge should be at least 7 tons of refuse to 1 wet ton of
sludge (7 Mg of refuse to 1 wet Mg of sludge). Usually, only sludges
with solids contents of 20% or more are mixed with refuse in such
operations and fewer operational and environmental problems may be
expected than when a 3% solids sludge is received. Also, less bulking
agent is required and ratios as low as 4 tons of refuse to 1 wet ton of
sludge (4 Mg of refuse to 1 Mg of sludge) are successfully practiced.
Also as shown above, sludge application rates for sludge/refuse mixtures
compare favorably with other methods, despite the fact that sludge is not
the only waste being disposed on the land. Application rates generally
range from 500 to 4,200 yd3 of sludge per acre (900 to 7,900 m6 of
sludge per ha).
3-28
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3.6.3.2 Sludge/Soil Mixture
In a sludge/soil mixture operation, sludge is mixed with soil and applied
as interim or final cover over completed areas of the refuse landfill.
This is not strictly a sludge landfill ing method since the sludge is not
buried. However, it is a viable option for disposal of sludge at refuse
landfills which has been performed and should be used in many cases.
Relevant sludge and site conditions as well as design criteria are
presented in the following tabulation.
Sludge and Site Conditions
Sludge solids content
Sludge characteristics
Hydrogeology
Ground slopes
Design Criteria
- >_ 20%
- stabilized
- deep or shallow groundwater or
bedrock
- < 5%
Bulking required
Bulking agent
Bulking ratio
Cover soil required
Imported soil required
Sludge application
Equi pment
- yes
- soil
- 1 soil :1 si udge
- no
- no
- 1,600 yd3/acre (3,000 m3/ha)
- tractor with disc
One advantage of employing the siudge/soil mixture operation is that it
removes sludge from the working face of the landfill where it may cause
operational problems. Other advantages are that the mixture can be used
to promote vegetation over completed fill areas; a savings in fertilizer
can be realized; and siltation and erosion problems can be minimized.
One disadvantage of employing the sludge/soil mixture is that it general-
ly has greater manpower and equipment requirements than would be incurred
3-29
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by landfill ing the same sludge quantity at the working face. Another
disadvantage is that since the sludge is not completely buried, odors may
be more severe than for sludge/refuse mixtures. For this reason, only
well stabilized sludges are recommended for use in sludge/soil mixture
operations.
3.6.4 Sludge-Only or Codisposal
For a variety of reasons, consideration should be given to using codis-
posal methods for sludge disposal in lieu of sludge-only methods. The
advantages of using an existing refuse landfill instead of a new sludge-
only landfill include:
1. Shorter time delay. Processing of permits to dispose sludge at
an existing refuse landfill will probably be quicker than proc-
essing permits for a new sludge-only site. Also, since most or
all of the site preparation required for sludge disposal is in
place, delays for construction may not occur.
2. Less environmental impact. The environmental impact (odors,
traffic, aesthetics, water) of one codisposal site will probably
be less than the combined impacts from two separate sites.
3. Less public opposition. The public is less likely to resist an
expansion in the operations of one site than it is to resist the
operation of a new site.
4. Less cost. Due to economies of scale, the cost of one codis-
posal site will probably be less than the combined costs of two
separate sites.
Obviously, there are several disadvantages for refuse landfill operators
to consider when contemplating the receipt of sludge. These include:
1. Odors may increase somewhat depending upon the degree to which
the sludge is stabilized.
2. Leachate may be generated sooner (if not already existing) or
leachate quantities may increase (if already existing).
3. Operational problems may develop including equipment slipping or
becoming stuck in sludge, or sludge being tracked around the
site by equipment and haul vehicles.
Several other items should be considered by a refuse landfill before
receiving sludge. These include:
3-30
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1. Pertinent regulatory authorities should be consulted to
ascertain whether sludge receipt is permissible.
2. Leachate collection and treatment systems may have to be
enlarged (if existing) or installed (if not existing) to handle
any increased leachate quantities.
3. Leachate treatment systems may have to be upgraded to handle any
change in leachate quality.
4. A sufficient volume of refuse should be delivered to the site so
that sufficient absorption of sludge moisture can occur.
5. Ideally, delivery of sludge and refuse should occur simulta-
neously. If not, storage capacity must be provided for either
sludge or refuse so that the sludge can be mixed with refuse
when landfilled.
6. Controlled dumping of refuse should occur to maximize its
absorptive capacity with sludge. Such control may not be
attainable when the public is allowed access to the working
face.
3.6.5 Conclusion
In Section 3.6, an attempt has been made to identify and describe the
major sludge landfilling methods. Sludge and site conditions as well as
design criteria have been presented for each method. Chapter 4 will
discuss the considerations and methodologies employed during the site
selection process.
In practice, the selection of a landfilling method is an integral part of
the site selection process. Indeed, it is imperative that the landfil-
ling method be known prior to the final site selection since the
acceptability of a given site is contingent upon the landfilling method
to be employed. By the same token, the acceptability of a given
landfilling method is contingent upon the site on which it is to be
employed. And, of course, the acceptability of a given combination of
landfilling method and site are in turn contingent upon the characteris-
tics of the sludge received. Obviously then, a thorough investigation of
sludge characteristics should be performed first, with concurrent
investigations of sites and landfilling methods to follow.
Tables 3-7 and 3-8 are compilations of the conditions and criteria pre-
sented previously for each landfilling method. They are provided to give
guidance during the investigation of alternative sites and landfilling
methods. It is important to note that there may be no one best method
3-31
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for a given sludge or site. Rather, these considerations and criteria
merely suggest sites and amenable landfill ing methods that can simplify
and improve the design and operation procedures required for an
environmentally safe and cost-effective sludge landfill.
TABLE 3-7
SLUDGE AND SITE CONDITIONS
Method
Narrow trench
Wide trench
Area fill mound
Area fill layer
Diked containment
SI udge/ refuse mixture
Sludge/soil mixture
SI udge sol ids
content Sludge characteristics
15-28% Unstaoilized or
stabi 1 i zed
>20% Unstabilized or
stabil ized
>20% Stabilized
>lb% Unstabilized or
stabil ized
>20% Stabilized
>3% Unstabil ized or
stabi 1 i zed
>2(K Stabilized
Hydrogeol ogy
Deep groundwater
and bedrock
Deep groundwater
and bedrock
Shallow groundwater
or beorock
Shallow groundwater
or bedrock
Shallow groundwater
or bedrock
Deep or shallow
groundwater or
bedrock
Deep or shallow
groundwater or
bedrock
Ground
slope
<20%
<10l
Suitable for steep terrain
long as level area is pn
pared for mounding
Suitable for medium slopes
level ground preferred
Suitable for steep terrain
long as a level area is
prepared inside dikes
<30%
<5%
6S
bjt
as
3.7 References
1. Wyatt, M. J. and P. E. White, Jr. Sludge Processing, Transporta-
tion, and Disposal/Resource Recovery: A Planning Perspective.
Report No. EPA-WA-75-R024. December 1975.
2. Process Design Manual Sludge Treatment and Disposal. U.S. Environ-
mental Protection Agency. Technology Transfer. Report No.
EPA-625/1-74-006. October 1974.
3. Sludge Treatment and Disposal, Part I. Introduction and Sludge
Processing. U.S. Environmental Protection Agency. Environmental
Research Information Center, Cincinnati, OH. Seminar Handout. May
1978.
4. General Pretreatment Regulations for Existing and New Sources of
Pollution. U.S. Environmental Protection Agency. Federal Register.
June 26, 1978. Part IV.
5. Burd, R. S. A Study of Sludge Handling and Disposal. U.S. Depart-
ment of the Interior. FWPCA. WP-20-4. May 1968.
3-32
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^ C
CB .rt
•a .e
CO O
o c
r-l
CD
(U 01 C
GOT3 CD
"O -H +->
3 >-) C
^H O O
CO t/l U
C S
CD (^
S -H
PH 3
DO 3
T3 P
3 X
3-33
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6. Weber, W. J. Physicochemical Processes for Water Quality Control.
Wiley-Interscience, New York, NY. 1972.
7. SCS Engineers. Review of Techniques tor Treatment arid Disposal of
Phosphorous-Laden Chemical Sludges. U.S. Environmental Protection
Agency, Contract No. 68-03-2432. 1978.
8. Smith, J. E. Jr., et al. Sludge Conoitioning with Incineration Ash.
Presented at the 27th Purdue Industrial Waste Conference. May 2-4,
1972.
9. Wastewater Engineering. Metcalf & Eddy, Inc. McGraw-Hill Book Co.,
New York, NY. 1972.
10. Walker, J. M., L. Ely, et al. Sewage Sludge Entrenchment System for
Use by Small Municipalities. U.S. Environmental Protection Agency,
National Environmental Research Center, Cincinnati, OH. 1976.
11. Walker, J. M., W. D. Burge, R. L. Chaney, E. Epstein, and J. D.
Menzies. Trench Incorporation of Sewage Sludge in Marginal
Agricultural Land. Report No. EPA-600/2-75-034. September 1975.
12. Report to the National Commission on Water Quality on the Environ-
mental Impact of the Disposal of Wastewater Residuals. Environ-
mental Quality Systems, Inc., Rockville, MD. March 1976.
13. Burge, W. D. and W. N. Cromer. Virus Survival and Movement from
Entrenched Sludge. In: Report on Cooperative Research Dealing with
Safe Utilization of Sludges (unpublished). March 1977. pp. 36.
14. Sieger, R. B. and P. M. Mahoney. Sludge Transport and Disposal,
Part II. Sludge Disposal. U.S. Environmental Protection Agency.
Environmental Research Information Center, Cincinnati, OH. Seminar
Handout. May 1978.
3-34
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CHAPTER 4
SITE SELECTION
4.1 Purpose and Scope
The purpose of this chapter is to present the technical and economic
considerations relevant to site selection and describe the methodologies
for applying these considerations to the site selection process. The
major divisions of this chapter are:
1. Site Considerations
a. technical
b. economic
2. Selection Methodology
3. Example of Methodology
The first part of this chapter is directed at those considerations which
determine the suitability of a site for sludge landfill ing. The
landfill ing method selected affects the suitability of a site and this is
described in Chapter 3, Sludge Characteristics and Landfill ing Methods.
Public acceptance also affects the suitability of a site and this is
described in Chapter 2, Public Participation Program. The second part of
this chapter presents a methodology for site selection. The third part
of this chapter includes an example of the methodology which will help
the user to understand a general procedure for selecting a sludge
landfill site.
It is important to emphasize the lead time necessary to select a site.
The permitting process, evaluation, public review, purchase, and
development of a landfill site may take a year or more. If the
municipality does not correctly anticipate the time requirements, overuse
and abuse of the existing landfill may result; at the very least the
municipality will be forced into expensive storage or transportation of
sludge.
4.2 Site Considerations
The technical considerations involved in selecting a sludge landfill site
span many disciplines: land use planning, economics, engineering, and
4-1
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social and political
must be considered in
fields. Among the technical
the evaluation process are:
considerations that
1. Site life and size
2. Topography
3. Surface water
4. Soils and geology
5. Groundwater
6. Vegetation
7. Site access
8. Land Use
9. Archaeological or
historical significance
10. Environmentally sensitive
areas
11. Costs
4.2.1 Site Life and Size
The site life is determined by the size of the site, the quantity and
characteristics of the sludge, and the landfill ing method. In
determining the required size, one must realize that not all the site can
be filled. Thus, a site should be viewed in the following terms:
1.
2.
Gross area. The total area within the property boundaries.
Usable fill area,
soil stockpiles.
to 70% of the gross
Excludes areas for buffers, access roads, and
Typically the usable fill area can consume 50
area
Figure 4-1 demonstrates calculations used to determine the required site
size given the site life, landfill ing method, and daily sludge
generation. Figure 4-2 on the other hand, calculates the site life given
the usable area, sludge quantity, and landfill ing method. Although in
practice a municipality will usually not define the site life initially,
a minimum acceptable life should be established, since
become less significant over an extended period.
start up costs
The landfill ing method also has an impact on site life and size. For
example, a wide trench method uses less land than a narrow trench
operation, and thus provides a longer site life, all other factors being
equal.
4.2.2 Topography
Since a relatively flat site could pond, and an excessively steep site
could erode and create operational difficulties, sludge landfilling is
4-2
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FIGURE 4-1
SAMPLE CALCULATION: AREA REQUIRED
Given:
1. Waste volume = 60 yuj/day, 7 days/week, 29% so1 >-i sludge
2. Trench 1 ife - 10 yr3
3. Trench dimensions = 45 ft wide x 10 ft deep x 2UO ft long
4. Trench spacing = 10 ft of solid ground between trenches
5. Buffer = 100 ft minimum, froir ">able filling area to areperty lire
Solutions:
!. Trench volume needed:
(60 yd3/day)x(365 days/yr)x(10 yrb) = 219,000 yd3
2. Number of trenches needed:
(219,000 yd3)x(27 ft3/yd3)
(45 ft x 10 ft x 200 ft) = 65.7 trenches
3. Usable acreage needed:
45 ft wide x 200 ft long trenches plus 10 ft between trenches
= 55 ft x 210 ft grojs space for each trench
(65.7 trencbes)x(55 ft x 210 ft trench) = T& 335 ft2
(758 835 ft2)
(43,560 ft^/acre -= 17.4 acres
4. Minimum Gross Acreage Required:
17.4 acres = 870 ft x 870 ft
Minimum site size = (1,070 ft x 1,070 ft) + 25% for access
roads, dumping pad, and miscellaneous uses = 33 acres
1 ft = 0.305 m
1 yd = 1.609 m
1 acre = 0.405 ha
FIGURE 4-2
SAMPLE CALCULATION: SITE LIFE AVAILABLE
Given:
1. Waste Volume = 45 yd3/day, 7 days/week, 22% solids sludge
2. Usable fill area = 6 acres
3. Trench dimensions = 10 ft wide x 5 ft deep x 120 ft long
4. Trench spacing = 5 ft of solid ground between trenches
Calculations:
1. Number of available trenches:
Each trench will have area = 15 ft x 125 ft = 1,875 ft?
Total acreage = 6 acres = 261,360 ft2
Number of trenches = 261,360 ft2'
1,875 ft'
= 139 trenches
2. Trench volume available:
(139 trenches)x(]0 ft x 5 ft x 120 ft) 1 vd3 ,
___h x 27ft3 • 30,089 yd3
3. Site life:
30,889 yd3
45 ydVday = 686 days = 1.9 yrs
1 ft = 0.305 m
1 yd = 1.609 m
1 acre = 0.405 ha
4-3
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usually limited to areas that have slopes greater
20%. Again, the landfill ing method determines
operations are amenable to a given topography.
than 1% and less than
to some extent what
4.2.3 Surface Water
The amount and nature of surface water -bodies on a landfill are a
significant factor in site selection. The existing bodies of surface
water and drainage on or near proposed sites should be mapped and their
current and future use considered. Certain areas such as wetlands and
flood plains should be avoided if at all possible since they are
environmentally sensitive areas [1]. Where it is necessary to use either
wetlands or floodplains the owner should be prepared to perform extensive
designs, provide operational controls of runoff and infiltration, prepare
environmental reports, and spend additional time obtaining approvals from
regulatory agencies.
In addition, the Clean Water Act of 1977 requires that all point source
discharges of pollutants (e.g., surface leachate or leachate treatment
effluent) must comply with NPDES permits issued for the facility. Thus,
selection of a site with surface water can compound design and
operational difficulties and increase the difficulty in securing a
permit. This should be considered during the selection process.
4.2.4 Soils and Geology
The role of soil in sludge landfills is to provide cover, attenuate
potential contaminants, control runoff and leachates, and serve as a
bulking agent (if the sludge characteristics and landfilling method
warrant). The chemical and physical/hydraulic properties of a soil
determine how effective it will be in performing these roles.
Accordingly, relevant soil properties that should be noted during the
selection process are:
1. Physical/hydraulic properties
a. Texture
b. Structure
c. Soil depth and quantity
d. Permeabil ity/transmissivity
2. Chemical properties
a. pH
b. Cation exchange capacity (CEC)
4-4
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In general, a desirable geology will have some combination of deep and
fine-textured soils. The finer the soil, the less depth needed. Sites
operating on clay and clay loams, for instance, have operated success-
fully with as little as 2 to 5 ft (0.6 to 1.5 m) of soil separating
sludge deposits from the highest groundwater elevations. Other soils
require a considerably greater thickness. The amount and type of soil
needed depends on the landfill ing method and the characteristics of the
sludge disposed [2]. Figure 4-3 gives the textural classifications used
by the U.S. Department of Agriculture, Soil Conservation Service (SCS).
FIGURE 4-3
SOIL TEXTURAL CLASSES AND GENERAL TERMINOLOGY
USED IN SOIL DESCRIPTIONS
U S. STANDARD SIEVE NUMBERS
10 20 40 60 200
1 1 I I i i I Tl 1 1 1 1
i
^
SAND
Ul
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(EK
Ul<
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111
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tc
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3
a
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2
U
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u.
££
SILT
CLAY
i I i i .1 I I 1 L L J
« - « 8 oSSSggs
°6 o o o o P P
GRAIN SIZE, mm O o O
4-5
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Permeability is dependent on the soil texture and structure. Again,
fine-grained, poorly structured soils have the lowest permeabilities.
Table 4-1 and Figure 4-4 give qualitative ranges for classifying soil
permeabilities. Depending on the sludge characteristics, a moderately
low to low permeability soil is desirable for a sludge landfill site,
although proper landfilling has been observed in relatively permeable
soils. As with texture, there is an inverse relationship between the
required soil thickness and soil permeability.
TABLE 4-1
PERMEABILITY CLASSES FOR
SATURATED SOIL [3]
Soil permeability (cm/s)
Class
<4.2 x 10-5
4.2 x 10-5 to 1.4 x 10-4
1.4 x 10-4 to 4.2 x 10-4
4.2 x 10-4 to 1.4 x 10-3
1.4 x 10-3 to 4.2 x 10-3
4.2 x 10-3 to 1.4 x ID"2
>1.4 x 10-2
Very slow
Slow
Moderately slow
Moderate
Moderately rapid
Rapid
Very rapid
FIGURE 4-4
SOIL PERMEABILITIES AND SORPTIVE
PROPERTIES OF SELECTED SOILS
INCREASING
SORPTION
CAPACITY
PERMEABILITY
10 10 10 10 10 10 10 10 I 10
TYPICAL SOIL TYPES
I SANDS, SANDY GRAVELS
I SILTS, SLTY SANDS,
SILTY SANDY GRAVELS
I CLEAN I
6RAVELS
4-6
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The climate also influences the soil requirements of a specific site. In
an area with high rainfalls, for example, soils with permeabilities that
are lower than the sludge permeabilities could result in the so-called
"bathtub" effect: a situation in which water accumulates in the trench
areas and cannot drain. If impermeable soils are to be used in these
areas, it may be necessary to install leachate collection systems.
The pH and cation exchange capacity (CEC) influence the ability of soils
to attenuate cations [3], Heavy metals are frequently held by alkali
soils. The CEC is determined to a large extent by the clay content of
the soil but it increases in direct proportion to the pH dependent
charged particles (hydrous metal oxides and organic matter) in the soil.
Table 4-2 shows typical ranges for CEC values in various soils. Soils
with higher CEC values are more efficient at removing cations and are
therefore desirable at a sludge landfill site. Other significant con-
siderations concerning soils are compaction characteristics, drainage,
and slope stability. These are summarized in Figure 4-5.
TABLE 4-2
TYPICAL RANGES OF CATION EXCHANGE
CAPACITY OF VARIOUS TYPES OF SOILS [3]
Range of CEC,
Soil type meg/100 g
Sandy soils 1 to 10
Silt loams 12 to 20
Clay and organic soils Over 20
The structural and mineralogical characteristics of the aquifer should be
delineated so that the potential for contamination can be accurately
assessed. Faults, major fractures, and joint sets should be identified
for candidate sites. Where these features are in hydraulic contact with
an aquifer, contamination could occur. Karst terrains and other solu-
tional formations should be avoided. In general, limestone, dolomite,
4-7
-------
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FIGURE 4-5
UNIFIED SOIL CLASSIFICATION SYSTEM AND CHARACTERISTICS
+~- a
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NSS
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jri ( Stantl.nl AASHO (Standard Proctor) conpactive
O O.H
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4-8
-------
and heavily fractured crystalline rock are less desirable than sedimen-
tary and consolidated alluvial bedrock.
4.2.5 Groundwater
Groundwater can generally be classified into two components. The first
is that groundwater located within the zone of saturation. The second is
known as interstitial water and includes groundwater located in the zone
of aeration. For the purposes of this section, discussions of ground-
water are directed toward water within the zone of saturation.
In assessing the suitability of a site for sludge landfill ing, collection
and evaluation of data on local aquifers is essential. The information
should include depth to groundwater (including historical highs and
lows), the hydraulic gradient, the quality of the groundwater, its cur-
rent and projected use, and the location of primary recharge zones.
Figure 4-6, a schematic representation of the hydrogeological cycle,
illustrates these principles.
FIGURE 4-6
HYDROGEOLOGICAL CYCLE [4]
PRECIPITATION
SURFACE
' RUNOFF
DISCHARGE
AREA
ZONE
OF
ARBATJON
till
SUBSURFACE MOVEMENT
LIMESTONE SOLUTION WIDENED JOINTS
CTmiii—I—r
PERMEABLE SANDSTONE
AQUICLUDE
4-9
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Sludge should not be placed where there is a potential for direct contact
with the groundwater table. Also, major recharge zones should be
eliminated from consideration, particularly sole source aquifers. As
much distance as possible should be maintained between the bottom of the
fill and the highest known level of groundwater.
Sources of data on groundwater quality and movement include the U.S
Geological Survey (USGS) "Groundwater Data Network", local well drillers,
State geological surveys, State health departments, other State
environmental and regulatory agencies, and samplings from nearby wells.
The USGS also publishes an annual report entitled "Groundwater Levels in
the United States" in the Water-Supply Paper Series. The data for this
paper is derived from some 3,500 observation wells located across the
nation.
If necessary, further background information on groundwater should be
collected by performing on-site drilling. The following information is
relevant to evaluating a site:
1. Groundwater elevations and fluctuations
2. Hydraulic gradient
3. Groundwater quality
The hydraulic gradient is equivalent to the slope of the groundwater
table (or the slope of the piezometric surface for an artesian aquifer).
Determining the hydraulic gradient of the site is important in ascer*-
taining the rate and amount of groundwater movement and whether or not
hydraulic connections to surrounding aquifers exist. The direction of
groundwater flow (and thus the hydraulic gradient) can be determined by
noting the depth to groundwater in nearby wells or borings, calculating
the elevation of the groundwater, and drawing contour lines that connect
wells of equal groundwater elevations.
At least three wells—and normally more—are needed to determine the
direction of groundwater flow. Usually large sites, sites with complex
hydrogeology, and/or relatively flat sites require more borings than
small sites. An experienced hydrogeologist should participate in the
research and exploratory drilling to interpret field data. He can
recommend the number, location, and type of exploratory wells needed.
Table 4-3 summarizes log tests and the information available from them.
4.2.6 Vegetation
The amount and type of vegetation on a prospective site should be con-
sidered in the selection process. Vegetation can serve as a buffer and
4-10
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TABLE 4-3
SUBSURFACE LOGGING INFORMAflON
OBTAINED BY VARIOUS METHODS [3]
Method
Drillers' log
Drilling-time log
Resistivity log
Operation
Information
Potential log
Temperature log
Cal(per log
Current log
Radioactive log
Observe well cuttings
during drill ing
Rock contacts, thickness,
description, or type texture.
Samples for laboratory tests.
Common method.
Observe drilling time Rock texture, porosity.
Measure electrical
resistivity of media
surrounding encased
hole
Measure natural
electric potential, or
self-potential
Measure temperature
Measure hole diameter
Measure current
Measure attenuation of
gamma and neutron rays
Specific resistivity of rocks
porosity, packing, water
resistivity, moisture content,
temperture, groundwater
quality. Correlate with
samples for best results.
Common method.
Permeable or impermeable,
groundwater quality. Common
method.
Groundwater circulation, leakage.
Hole diameter, rock consolidation,
cavimj zones, casing location.
Groundwater flow velocity, circu-
lation, leakage.
Consolidation, porosity, moisture
content. Common in soil studies,
clay or nonclay materials.
reduce dust, noise, odor and visibility. However, where extensive
logging and/or clearing of vegetation is necessary, it can increase costs
prohibitively.
4.2.7 Site Access
The haul routes to the prospective sites should utilize major highways to
the maximum extent possible. Potential routes should be driven and
studied to determine the physical adequacy of roadways for truck traffic;
the approximate number of residences, parks, and schools fronting the
roads; and the probable impact on traffic congestion.
4-11
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4.2.8 Land Use
The zoning of each prospective site should be considered from the per-
spective of both current and future standards. The appropriate county or
municipal zoning authority should be contacted to determine zoning status
or restrictions as they pertain to each site. Completed site use of the
sludge landfill should be considered early in the selection process and
evaluated relative to future zoning (see Chapter 8, Completed Site).
Regional development should also be considered in site selection, and
existing master plans for the area should be consulted. The evaluation
of current and future development may present the opportunity for a more
strategically centralized location of the sludge landfill. Moreover, the
projected rate of industrial and/or municipal development and its
location affect the site size which will be needed to meet projected
demands.
4.2.9 Archaeological or Historical Significance
The archaeological or historical significance of the land involved in a
potential site should be ascertained. The determination of the histori-
cal status of a potential site is usually addressed in an environmental
impact report and should be performed by a qualified archaeologist/
anthropologist. Due to the expense involved in such studies, archae-
ological and historical investigations should be limited to the top
ranking candidates. Any finds of significance in relation to the
archaeology or history of the site must be accommodated before the site
can be approved and construction can begin.
4.2.10 Environmentally Sensitive Areas
The Classification Criteria for Solid Waste Disposal Facilities [1] now
being promulgated by EPA identify five environmentally sensitive areas.
These include:
1. Wetlands
2. Flood plains
3. Permafrost areas
4. Critical habitats of endangered species
5. Recharge zones of sole source aquifers
4-12
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In general, sludge landfills should not be located in environmentally
sensitive areas when feasible alternatives exist since both the technical
and administrative measures required will probably be more complex. In
addition, permits may be required for sludge landfill ing in such areas
(including wetlands and critical habitats).
4.2.11 Costs
Early in the selection process an economic screening of sites should be
performed to determine relative costs. In order to obtain a meaningful
figure that can be used to compare sites, capital and operating costs
should be estimated. This estimate may be computed as shown below. This
discussion does not account for the time value of money. For most sites,
particularly long-lived sites, this will tend to favor the selection of
sites with high capital costs over sites with relatively higher operating
costs. In some cases, it may be necessary to compute amortized capital
costs. However, the process described below is less complex and will be
accurate in the vast majority of cases.
1. Determine the capital costs (C) in dollars over the life of the
site. This should include primarily:
a. Land aquisition
b. Site preparation
c. Equipment purchase
2. Determine site life (L) in years.
3. Compute unit capital cost (P-|) in dollars/yd^ of sludge
based on proposed annual sludge quantity (Q) in yd-Vyr.
r
P. =
1 LQ
Determine total operating cost (0) in dollars over one year.
This should include primarily:
a. Labor
b. Equipment fuel, maintenance, and parts
c. Utilities
d. Laboratory analysis of water samples
e. Supplies and materials
f. Miscellaneous and other
4-13
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5. Compute unit operating cost (P£) in dollars/yd3 of sludge
based on proposed annual sludge quantity (Q) in yd /yr.
P
P2
6. Determine total hauling cost (H) in dollars over one year.
7. Compute unit haul cost (Pg) in dollars/yd of sludge based
on proposed annual sludge quantity (Q) in yd3/yr.
p = H
3 Q
o
8. Compute total annual cost (T) in dollars/yd of sludge,
T = P, + Po + P,
j. C- O
4.3 Site Selection Methodology
A site selection process may consist of the following stages:
1. Initial assessment of sites
2. Screening of candidate sites
3. Final site selection
Sections 4.3.1, 4.3.2, and 4.3.3 outline a selection procedure that has
been used. This procedure is summarized in Figure 4-7. Smaller sites
may not require a selection process as detailed as the one presented
below.
4.3.1 Initial Assessment of Sites
Step 1-1: Determine regulatory constraints (Federal, State, local) based
on:
1. Physical limitations (groundwater depth, maximum slope)
2. Demographical limitations (distance to nearest residence,
land-use factors)
3. Political limitations (public reaction, special interest
groups, budget management)
4-14
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4-15
-------
Step 1-2: Establish suitable study areas:
1. Determine maximum radius of study area based on haul
distance(s) from wastewater treatment plant(s) and/or
centroid of potential service area.
2. Use transparent (mylar) overlays to designate areas which
have:
a. inappropriate slope
b. dense population
c. undesirable geology (karst, fractured bedrock
formations, faults)
d. undesirable soil (shallow, high organics, permafrost
areas)
e. unsuitable surface or groundwater conditions (flood
plains, bogs, areas of ponding, marshes, recharge zones
of aquifers)
3. Place shaded mylars of these low suitability areas on study
area map. The unshaded area may be considered generally
suitable for landfill ing.
Step 1-3: Identify potential candidate sites:
1. Inform local realtors
2. Investigate past site inventories
3. Study maps or aerial photographs
4. Traverse roads in high probability areas for "For Sale" or
"For Lease" signs
Step 1-4: Assess economic feasibility (ballpark estimate based on
experience, rule of thumb, judgement) including:
1. Haul distances
2. Rough estimate of site development cost
3. Quantity of siudge
4. Operating hours per week for equipment and personnel
4-16
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Step 1-5: Perform preliminary site investigations using existing
information (see Chapter 5, Design) and tabulate information.
Pertinent information includes:
1. Location (drainage basin)
2. Land use(on and near site)
3. Haul distance and routes
4. Topography
5. Soil characteristics
6. Area of site
Step 1-6: Eliminate less desirable sites based on regulatory and
economic constraints and technical considerations.
Step 1-7: Obtain public input via the public participation program (see
Chapter 2). For example, a kick-off meeting would help to
determine the attitude of the citizenry early in the process.
Area residents also may assist in identifying candidate
sites.
4.3.2 Screening of Candidate Sites
Step 2-1: Determine methodology for screening candidate sites in terms
of the considerations listed below. Designate the degree of
detail required to fulfill regulatory requirements. Designate
a screening committee of qualified personnel. The methodology
may include scoring systems and other subjective analyses [5],
Again, the evaluation presented below may be more extensive
than necessary for small sludge landfills.
1. Technical considerations
a. haul distance
b. site life and size
c. topography
d. surface water
e. soils and geology
f. groundwater
g. soil quantity and suitability
h. vegetation
4-17
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i. environmentally sensitive areas
j. archaeological or historical significance
k,. site access
1. land use
2. Economic considerations
3. Public acceptance considerations
Step 2-2: Investigate 4 to 6 candidate sites and identify site specific
problems. Field investigations (see Chapter 5, Design) may be
appropriate to supplement information from existing sources.
However, the degree of detail and intensity of investigation
will vary from site to site.
Step 2-3: Evaluate sites. The sites may be evaluated in terms of the
potential adverse impact on the environment. A scoring system
similar to the one described in Section 4.4 may be useful in
quantitatively evaluating the candidate sites.
Step 2-4: Rate sites. The rating is based on technical considerations.
Step 2-5: Input site selection findings of top site(s) into an
environmental impact report (if required).
Step 2-6: Obtain public input.
4.3.3 Final Site Selection
Step 3-1: Prior to final site selection, the landfill ing method and
preliminary design should be ascertained for each site. These
designs should be compatible with sludge and site characteris-
tics (see Section 3.6). Preliminary drawings are prepared
in this phase.
Step 3-2: Evaluate alternative completed site uses and determine use for
each candidate site.
4-18
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Step 3-3: Evaluate economics in detail
1 . Site capital cost
2. Site operating cost
3. Haul ing cost
Step 3-4: Evaluate local government policies and obtain public input. A
public hearing may be scheduled to receive final comments from
local government officials and the public.
Step 3-5: Select site and list alternative sites.
Step 3-6: Acquire site. The following options are available:
1. Option to purchase and subsequent execution (await site
approval )
2. Outright purchase (after site approval by regulatory agency
and local jurisdiction)
3. Lease
4. Condemnation and/or other court action
5. Land dedication
4.4 Example of Methodology
This section presents an example of a methodology used for selecting a
landfill site. This example includes initial assessment, screening, and
final selection procedures. The procedures in this example employ
numerical scoring systems. However, in some cases it may be more
appropriate to use a qualitative system (e.g., using terms such as
suitable, marginally suitable, not suitable in lieu of numerical
ratings). In this example, the study area was a large county in the
mid-Atlantic region.
4-19
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4.4.1 Initial Assessment of Sites
The initial step was to use overlays to narrow the study area to that
portion of the county where technically suitable sites were most likely
to be found.
1. Overlay No. 1. Shaded areas having questionable soils. The
soils were evaluated in terms of soil permeability and runoff
characteristics. The SCS District Manager and the Cooperative
Extension Service were sources for this information.
2. Overlay No. 2. Shaded areas containing possible topographical
limitations. These included flood plains and a small watershed
which drained to a vital drinking water supply.
3. Overlay No. 3. Shaded areas having questionable geology. State
geologists were consulted to determine areas where shallow soil
which covers fractured bedrock existed.
The overlays were placed over a county map and the unshaded areas were
considered generally suitable for sludge landfill ing (see Figure 4-8).
FIGURE 4-8
INITIAL ASSESSMENT WITH OVERLAYS
LEGEND
UNSUITABLE SOILS
TOPOGRAPHIC LIMITATIONS
UNSUITABLE GEOLOGY
S-l • CANDIDATE SITE
4-20
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After identifying all feasible sites (13 in this case), a preliminary
investigation of technical data was performed. The results were
tabulated in Table 4-4. Based on the information compiled in Table 4-4,
these 13 sites were then evaluated relative to the criteria listed in
Step 1-5 of Section 4.3.1. Based on this evaluation, 9 of the sites were
eliminated from futher considerations. The 4 remaining sites were
identified as S-5, S-10, S-ll, and S-13.
4.4.2 Screening of Candidate Sites
The screening process began with the collection of more detailed informa-
tion on the remaining 4 sites. This data is compiled in Table 4-5. A
scoring system was then applied as shown in Table 4-6 using the following
considerations.
1. Principal objectives of sludge landfills. The etablishment and
use of the site was based on certain objective. Objectives were
developed so that they were attainable, and the degree of
attainment was measurable. The scoring system employed contained
five principal objectives.
2. Rating of objectives by order of importance. The objectives were
listed in order of importance, and a value was assigned to each
objective to reflect its relative importance. Once this was
accomplished, experience showed that many of the originally
listed objectives appeared insignificant and were therefore
discarded.
3. Criteria. Having listed the objectives, criteria which measured
the ability of a site to attain that objective was then
developed.
4. Relative ability of criteria to fulfill objective. The criteria
for each objective then was assigned numerical values that
reflected their relative ability to measure most exactly the
attainment of the objective, rather than their individual
significance.
5. Maximum score. Based on values in columns (2) and (4), the
maximum score was calculated for each criterion. For example the
objective of public health has a rating of 1,000. The criteria
of a groundwater pollution hazard rates 10 out of a total of 34
total points for all public health criteria. Therefore,
(10/34)x(l,000) = a maximum score of 244 points
6. Prospective landfill sites. All sites were compared relative to
one criterionByassigning a numerical value (rating) that
reflected the site's ability to satisfy the criterion being
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-------
examined, it was eliminated from further consideration). Various
specialists scored the sites under criteria involving their area
of expertise. For example, planners were used to score those
criteria related to land use.
The scoring was found to be more effective when all sites were evaluated
relative to one criterion before other criteria were examined. Each
criterion was given a score ranging from 1 to 10, the higher score
represented the desirable direction. Thus, a site with no "potential
groundwater pollution hazard", for instance, received a score of 10. The
rating was then assigned a pro-rated score. For example, the potential
groundwater pollution hazard rating for S-5 was 7; therefore, the
pro-rated score = (7/34)x(1,000) = 206
4.4.3 Final Site Selection
Following the scoring system, an economic evaluation of the top sites was
performed and documented in Tables 4-7 and 4-8. The total cost was
calculated using the following formulas to determine pro-rated cost
(S/yd-3) over the life of the site based on the projected sludge
volumes.
TABLE 4-7
OPERATING COST ESTIMATES
Site no.
Description S-5 S-10 S-11 S-13
One Full-Time Equipment Operator
Cost Includes an Allowance of
30% for Fringe Benefits $ 15,000 $ 15,000 $ 15,000 $ 15,000
Equipment Operation and
Maintenance 15,000 15,000 15,000 15,000
Site Operation and Maintenance 5,000 5,000 3,000 4,000
Leachate Haul Costs 1,000 — 1,000
Cover Material Purchase 25,000 — 40,000
Temporary Road Surfacing,
Access and Highway Cleaning 20,000 15,000 15,000 8,000
Groundwater Monitoring Samples 3,000 2.000 2,000 2.000
Subtotal of Site Costs $ 84,000 $ 52,000 $ 91,000 $ 44,000
Sludge Hauling Cost 15.000 150,000 25,000 75,000
Total Operating Cost/yr $99,000 $202,000 $116,000 $119,000
Unit Cost ($/yd3) based
on 18,000 yd3/yr $5.50 $11.22 $6.44 $6.61
1 yd3 = 0.7646 m3
4-26
-------
TABLE 4-8
CAPITAL COST ESTIMATES
Description
Site no.
S-i.
Land Acquisition
Number of Acres 20
Cost per Acre 3,300
Purchase Price 66,000
Site Development Costs
Initial Site Preparation 50,000
Clearing and Grubbing 120,000
Fence and Gate 10,000
Access Roadway (On-Site) 8,000
Leachate Collection System 20,000
Storm Water Managanent 15,000
Reconstruct Primary Access
Roadway
Equipment Storage Shed
Utl 1 Hies
Mom toriruj
Subtotal
Engineering Surveying
Subsurface Exploration
and Penmts (2051)
Contingency (10%) of Land 31,000
Acquisition and Site
Development Costs
Equipment
Backhoe Loader
Total Capital Cost
Estimated Site Life (yrs)
Unit Cost ($/yd3) based on
18,000 yd3/yr 2.30
30,000
2,000
12,000
16,000
20,000
30,000
3,000
10,000
3,000
25,000
15,000
2.76
S-13
37 25 30
8,000 2,000 8,300
296,000 500,006 249,000
15,000 15,000
2,000 3,000
4,000 4.000
310,800 398,000 157,000 461,000
62,000 79,600 31,400 92,200
39,800 15,700 46,100
80,000 120,000 30,000
597,400 324,100 674,300
12 10 12
3.12
1 yd-*
0.7646
1 ac <= 0.4047 ha
A compilation of data impacting on the final site selection was then
assembled in Table 4-9. As shown, the technical prioritization of the
sites was S-ll, S-13, S-5, and lastly S-10; the cost prioritization was
S-5, S-ll , S-13, and S-10; and the public acceptance prioritization was
S-13, S-5, S-ll, and S-10. In this example, Site S-13 was selected on
the basis of its (1) top public acceptance ranking, (2) longer life, and
(3) completed site use as a needed park. Although S-13 was not the
top-ranked site technically, it was determined to be acceptable. Also,
the cost of S-13 was relatively high; however, the operating agency was
forced to absorb these costs due to the obvious site benefits.
4-27
-------
TABLE 4-9
FINAL SITE SELECTION
Map
ref.
S-5
S-10
s-n
S-13
Site name/
location
Alton Street
Site
Hunter Road
Site
Harringon
Blvd. Site
Gilford
Road Site
Scoring
system
value
1,773
1,538
2,534
2.230
Landfill ing
' method
Area fill
mound
Wide trench
Area fill
mound
Wide trench
Proposed
final site
use
Open space
Return to
natural state
Pasture
Park
Site
life
10 yrs
12 yrs
10 yrs
12 yrs
Total annual
cost
($/yd3)a
7.80
13.98
8.24
9.73
Public
acceptance
ranking
3
2
4
1
a Sum of capital and operating costs
° Provided from attitude survey taken at public meetings.
Lower numbers represent less opposition
1 yd3 = 0.7646 m3
4.5 References
1. Proposed Classification Criteria for Solid Waste Disposal Facilities.
U.S. Environmental Protection Agency. Federal Register. February 6,
1978.
2. Weaver, D.E., C.J. Schmidt, and J.P. Woodyard. Data Base for
Standards/Regulations Development for Land Disposal of Flue Gas
Cleaning Sludges. U.S. Environmental Protection Agency, Cincinnati,
OH. Report No. EPA-600/7-77-118. December 1977. pp. 146-148.
3. Process Design Manual for Land Treatment of Municipal Wastewater.
U.S. Environmental Protection Agency. Technology Transfer. Report
No. EPA-625/1-77-008. October 1977. pp. C-13-C-19.
4. Brunner, D.R. and Keller, D.J. Sanitary Landfill Design and Opera-
tion. U.S. Environmental Protection Agency. Washington, DC. Report
No. SW65ts. 1972. pp. 17.
5. Sexsmith, D.P. et al. Selection Criteria, Methods, and Scoring
System for Sanitary Landfill Site Selection. J_n: Proceedings of
Canadian Conference on Solid Waste. 1976. pp. 301-317.
4-28
-------
CHAPTER 5
DESIGN
5.1 Purpose and Scope
The objective of a sludge landfill design is to direct and guide the
construction and on-going operation of the landfill. A design should
ensure (1) compliance with pertinent regulatory requirements, (2) ade-
quate protection of the environment, and (3) cost-efficient utilization
of site manpower, equipment, storage volume, and soil. A design package
(consisting of all design documents) should be prepared to provide a
record of the landfill design. These may consist of drawings, specifi-
cations, and reports.
The purpose of this chapter is to provide guidance on the design of a
sludge landfill. Specific topics addressed include:
1. Typical permitting procedures and regulatory requirements
(Section 5.2)
2. Design methodology (Section 5.3)
3. Relevant data and sources of information (Section 5.3)
4. Contents of the design package (Section 5.3)
5. Information on specific landfill ing method designs (Sections 5.4
through 5.6)
6. Information on other designs (Sections 5.7 through 5.16)
5.2 Regulations and Permits
Many regulatory and approving agencies require permits before a sludge
landfill can be constructed or operated. The sludge landfill design is
generally an integral part of the application for such permits. Ac-
cordingly, all pertinent agencies should be contacted early in the design
phase to (1) identify regulations impacting on the prospective sludge
landfill, (2) determine the extent, detail, and format of the applica-
tion, and (3) obtain any permit application forms. Once this information
has been collected, the design can proceed in a more efficient manner
toward the goal of receiving the necessary permits.
5-1
-------
Requirements and permits relevant to sludge landfills are found to exist
on the State, and local levels. One program of concern is the EPA
Construction Grants Program administered by the Office of Water Program
Operations. Grants can be received from this source to cover up to 75%
of the capital costs (including land acquisition, equipment purchase, and
site preparation) for the entire sludge management system. Since this
system includes both in-plant sludge treatment facilities as well as
disposal facilities, the application must address the sludge landfill
operation as well. Accordingly, it is important to proceed with a
landfill design which is in accordance with EPA grant requirements if
grants are desired. Other Federal requirements relevant to sludge
landfills are contained in the Criteria for the Classification of Solid
Waste Disposal Facilities [1], These Criteria address the following
topic areas:
1. Environmentally sensitive areas
2. Surface water
3. Groundwater
4. Air
5. Application on land used for the production of food chain crops
6. Disease vectors
7. Safety
Environmentally sensitive areas are more specifically identified as (1)
wetlands, (2) flood plains, (3) permafrost areas, (4) critical habitats
of endangered species, and (5) recharge zones for sole source aquifers.
As stated in the Criteria, disposal facilities should not be located in
environmentally sensitive areas when feasible alternatives exist, unless
it can be clearly demonstrated that there will be no significant impact
on the ecosystem or human health from the operation of a facility in such
an area [1],
Safety concerns are more specifically identified as (1) explosive gases,
(2) toxic or asphyxiating gases, (3) fires, (4) bird hazards to aircraft,
and (5) access. As stated in the Criteria, disposal facilities should
not pose a safety hazard to facility employees, users, or the public with
respect to any of the above features. Requirements also exist in each of
the remaining topic areas and the Criteria should be consulted for a
complete description. Many of the requirements in the Criteria are
already addressed in State regulations. Table 5-1 provides an analysis
of the Criteria topic areas included in State regulations.
Several permits relevant to sludge landfills are identified and mandated
by these Criteria. Generally these include:
5-2
-------
1. NPDES permit required for location of a sludge landfill in
It is also required for any point source discharges
wetlands.
at sludge
landfill s.
2. Army Corps of Engineers permit required for the construction
any levee, dike, or other type of containment structure to
placed in the water at a sludge landfill located in wetlands.
of
be
3. Office of Endangered Species permit may
Fish and"Wildl ife Service, Department
location of a sludge landfill in critical
species.
be required from the
of the Interior for
habitats of endangered
State and local regulations and permits are highly variable from
jurisdiction to jurisdiction. Depending on the jurisdiction, one or more
permits may be required for a sludge landfill. Typical permits on the
State and local levels include:
1. Solid waste management permit
2. Special use permit
3. Zone change certification for a change to a zoning appropriate
for a sludge landfill
4. Sedimentation control permit for surface runoff into water
courses
5. Highway department permit for entrances on public roads and
increased traffic volumes
6. Construction permit for landfill site preparation
7. Operation permit for on-going landfill operation
8. Mining permit for excavations
9. Fugitive dust permit
10. Business permit for charging fees
11. Closure permit
12. Building permit to construct buildings on the landfill site
Depending on local procedures, permits may be required from both state
and local regulatory agencies. State regulatory agencies which require
such submittal s may include:
1. Solid waste management agencies
2. Water quality control agencies
3. Health departments
4. Building departments
5-3
-------
TABLE 5-1
ANALYSIS OF FEDERAL CRITERIA VS. STATE REGULATIONS [2]
State
Alabama
Alaska
Ari zona
Arkansas
Cal ifornia
Colorado
Connecticut
Delaware
Florida
Georgia
Hawai i
Idaho
[1 1 inois
I nd i a na
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryl and
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hamsphire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Okl ahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
% of Total
Environmentally Sensitive Areas
V>
Z
3
X
X
X
X
X
X
X
X
X
X
X
11/50
22%
c:
r-
?
o
£
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
23/50
45%
o
I-
E
11
X
1/50
2%
f_ ^
O T3
t^ .0
(-> 31
X
1/50
2%
11
t-
l t-
"o cr
O)
OJ
s
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
50/50
100%
Safety
11
V)
m
tu
l/l
o
ex
X
LJ
X
X
X
X
X
X
X
X
X
X
X
X
X
14/50
28%
V
t-
u.
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
41/50
82%
l/l
Ol
o
"
0
X
X
X
X
X
X
X
X
X
X
X
X
13/50
26%
•a
n3
•£
CL3
X
X
X
X
X
5/50
10%
V>
OJ
u
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
42/50
84%
% of
Total3
50%
60%
50%
70%
100%
60%
70%
60%
100%
70%
40%
60%
60%
80%
60%
40%
70%
20%
50%
90%
60%
70%
100%
50%
90%
60%
70%
60%
90%
90%
50%
50%
70%
30%
50%
50%
70%
70%
80%
50%
70%
70%
100%
40%
40%
50%
90%
40%
90%
60%
Environmentally sensitive areas counted as one criterion for row totals.
5-4
-------
Local regulatory agencies may include:
1. Health departments
2. Planning and/or zoning commissions
3. Board of county commissioners
In many jurisdictions more than one of the State or local agencies has
authority over a disposal site. Also, in some jurisdictions, one agency
has control over sludge-only landfills while another agency has control
over refuse landfills.
The reviewing agency may require the submittal of information on standard
forms or in a prescribed format in order to facilitate the review
process. In any event, applicants are responsible for the completeness
and accuracy of the application package. The completed application
package is then reviewed by the regulatory agency. The time of the
review period will vary depending upon the regulatory agency, their
attention to detail, the number of applications preceding it, etc. From
experience, this process has been found to take at least one month and
usually 6 to 12 months or longer. After a permit is issued, it can be
valid for various durations, depending largely upon the submittal of
inspection/ performance reports and the outcome of on-site inspections.
5.3 Design Methodology and Data Compilation
Adherence to a carefully planned sequence of activities to develop a
sludge landfill design minimizes project delays and expenditures. A
checklist of design activities is presented in Table 5-2. These
activities are listed somewhat in their order of performance. However,
in many cases separate tasks can and should be performed concurrently or
even out of the order shown.
As shown in Table 5-2, initial tasks consist of compiling existing
information and generating new information on sludge and site conditions.
Obviously, some of this information would have already been collected in
the site selection phase. Generally however, additional and more
detailed information will have to be collected in the design phase.
Information utilized during both the site selection and design phases can
be derived either from existing sources or new sources (i.e., field
investigation). A listing of possible existing information sources has
been included as Table 5-3. A listing of possible new information
sources has been included in Table 5-4.
5-5
-------
TABLE 5-2
SLUDGE LANDFILL DESIGN CHECKLIST
Step Task
1 Determine sludge volumes and characteristics
a. Existing
b. Projected
2 Compile existing and generate new site information.
a. Perform boundary and topographic survey
b. Prepare base map of existing conditions on-site and near-site
(1) Property boundaries
(2) Topography and slopes
(3) Surface water
(4) Utilities
(5) Roads
(6) Structures
(7) Land use
c. Compile hydrogeological information and prepare location map
(1) Soils (depth, texture, structure, bulk density, porosity, permeability,
moisture, ease of excavation, stability, pH, and cation exchange
capacity)
(2) Bedrock (depth, type, presence of fractures, location of surface
outcrops)
(3) Groundwater (average depth, seasonal fluctuations, hydraulic gradient and
direction of flow, rate of flow, quality, uses)
d. Compile climatological data
(1) Precipitation
(2) Evaporation
(3) Temperature
(4) No. of freezing days
(5) Wind direction
e. Identify regulations (Federal, State, and local) and design standards
(1) Requirements for sludge stabilization
(2) Sludge loading rates
(3) Frequency of cover
(4) Distances to residences, roads, and surface water
(5J Monitoring
(6) Roads
(7) Building codes
(8) Contents of application for permit
3 Design filling area
a. Select landfill ing method based on:
1) Sludge characteristics
2) Site topography and slopes
(3) Site soils
(4) Site bedrock
(5) Site groundwater
b. Specify design dimensions
(1) Trench width
(2) Trench depth
(3) Trench length
(4) Trench spacing
(5) Sludge fill depth
(6) Interim cover soil thickness
(7) Final cover soil thickness
5-6
-------
TABLE 5-2 (Continued)
c. Specify operational features
(1) Use of bulking agent
(2) Type of bulking agent
(3) Bulking ratio
(4) Use of cover soil
(5) Method of cover application
6) Need for imported soil
7) Equipment requirements
(8) Personnel requirements
d. Compute sludge and soil uses
(1) Sludge application rate
(2) Soil requirements
Design facilities
a. Leachate controls
b. Gas controls
c. Surface water controls
d. Access roads
e. Special working areas
f. Structures
g. Utilities
h. Fencing
i. Lighting
j. Wasnracks
k. Monitoring wells
1. Landscaping
Prepare design package
a. Develop preliminary location plan of fill areas
b. Develop landfill contour plans
(1) Excavation plans
(2) Completed fill plans
c. Compute sludge storage volume, soil requirement volumes, and site life
d. Develop final location plan showing:
(1) Normal fill areas
2) Special working areas
3) Leachate controls
(4) Gas controls
(5) Surface water controls
(6) Access roads
(7) Structures
(8) Utilities
(9) Fencing
(10) Lighting
(11) Washracks
(12) Monitoring wells
(13) Landscaping
e. Prepare elevation plans with cross-sections of:
(1) Excavated fill
(2) Completed fill
(3) Phased development of fill at interim points
f. Prepare construction details
(1) Leachate controls
(2) Gas control s
(3) Surface water controls
4) Access roads
5) Structures
(6) Monitoring wells
g. Prepare cost estimate
h. Prepare design report
i. Submit application and obtain required permits
j. Prepare operator's manual
5-7
-------
TABLE 5-3
SOURCES OF EXISTING INFORMATION
General Information
Specific Information
Source
Base Map
General
Soils
Bedrock
Groundwater
Topography and Slopes
Land Use
Vegetation
General
General
General
Climatology
General
• County road department
• City, county, or regional planning
department
t U.S. Geological Survey (USGS)
office or outlets for USGS map
sales (such as engineering supply
stores and sporting goods stores)
* U.S. Department of Agriculture
(USDA), Agricultural Stabilization
and Conservation Service (ASCS)
• Local office of USGS
• County Department of Agriculture,
Soil Conservation Service (SCS)
• Surveyors and aerial photographers
in the area
t USGS topographic maps
t USDA, ARS, SCS aerial photos
t City, county, or regional planning
agency
• County agricultural department
» Agriculture department at local
university
• USDA, Soil Conservation Service
(SCS), District Managers, Local
Extension Service
• USGS reports
• Geology or Agriculture Department
of local university
i USGS reports
• State Geological Survey reports
• Professional geologists in the area
• Geology Department of local
university
• Water Supply Department
• USGS water supply papers
» State or regional water quality
agencies
* USDA, SCS
• State or Federal water resources
agencies
• Local health department
• National Oceanic and Atmospheric
Administration (NOAA)
• Nearby airports
5-8
-------
Bedrock
Groundwater
Climatology
TABLE 5-4
FIELD INVESTIGATIONS FOR NEW INFORMATION
General
Information
Base Map
Soils
Specific Information
Property boundaries
Topography and slopes
Surface water
Utilities
Roads
Structures
Land use
Vegetation
Depth
Texture
Structure
Bulk density
Porosity
Permeabil ity
Moisture
Ease of excavation
Stability
pH
Cation exchange capacity
Method and Equipment
Field survey via transit
Field survey via al idade
Field survey via alidade
Field survey via alidade
Field survey via alidade
Field survey via alidade
Field survey via alidade
Field survey via alidade
Soil boring and compilation of boring log
Soil sampling and testing via sedimentation
methods (e.g., sieves)
Soil sampling and inspection
Soil sampling and testing via gravimetric,
gamma ray detection
Calculation using volume of voids and total
vol ume
Soil sampling and testing via piezometers and
lysimeters
Soil sampling and testing via oven drying
Test excavation with heavy equipment
Test excavation of trench and loading of
sidewall or Hueem stabilometer
Soil sampling and testing via pH meter
Soil sampling and testing
Depth
Type
Fractures
Surface outcrops
Depth
Seasonal fluctuations
Hydraulic gradient
Rate of flow
Quality
Uses
Precipitation
Evaporation
Temperature
No. of freezing days
Wind direction
Boring and compilation of boring log
Sampling and inspection
Field survey via alidade or Brunton
Field survey via alidade or Brunton
Well installation and initial readings
Well installation and year-round readings
Multiple well installation and comparison
of readings
Calculation based on permeability and
hydraulK gradient
Groundwater sampling and testing
Field survey via inspection
Rain gauge
Class A Evaporation Pan
Standard thermometer
Minimum-maximum temperature thermometer
Wind arrow
Before proceeding to the final design it is advisable to recontact
regulatory agencies who were contacted during the site selection process
and others to try to determine all of their requirements and procedures
for permit application submittals. This will also provide an opportunity
to discuss design concepts, get questions answered, and determine any
special or new requirements. Maintenance of close liaison with State and
local regulatory officials throughout the design effort is normally
helpful in securing a permit without excessive redesigns.
A complete design package may include plans, specifications, a design
report, cost estimate, and operator's manual. Generally, the
estimate and operator's manual are prepared strictly for
while plans, specifications, and design reports are
regulatory agencies in the permit application. Plans and specifications
typically include:
cost
in-house uses,
submitted to
5-9
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1. Base map showing existing site conditions. The map should be of
sufficient detail, with contour intervals of no more than 5 ft
(1.5 m) and a scale not to exceed 1 in. = 200 ft (1 cm = 24 m).
2. Site preparation plan locating sludge fill and soil stockpile
areas as well as site facilities. A small-scale version of a
site preparation plan has been included as Figure 5-1.
3. Development plan showing initial excavated and final completed
contours in sludge filling areas.
4. Elevations showing cross-sections to illustrate phased
development of sludge landfill at several interim points.
5. Construction details illustrating detailed construction of site
facilities.
6. Completed site plan including final site landscaping, appur-
tenances, and other improvements.
A design report typically includes:
1. Site description including existing site size, topography and
slopes, surface water, utilities, roads, structures, land use,
soils, groundwater, bedrock, and climatology.
2. Design criteria including sludge types and volumes and fill area
design dimensions.
3. Operational procedures including site preparation, sludge
unloading,sludge handling, and sludge covering as well as
equipment and personnel requirements.
4. Environmental safeguards including control of leachate, surface
water, gas, odor, flies, etc.
5.4 Selection of Landfill ing Method
Several alternative methods and sub-methods for sludge landfill ing were
identified and described in Chapter 3, Sludge Characteristics and
Landfill ing Methods. These include:
1. Sludge-only trench
a. narrow trench
b. wide trench
5-10
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FIGURE 5-1
TYPICAL SITE PREPARATION PLAN
— T
LEGEND
-- EXISTING CONTOURS
PROPERTY BOUNDARY
= ROADS
-M- RAILROAD
— TRANSMISSION LINE
—• STREAM
^ POND
| DWELLINGS
I PUBLIC BUILDINGS
WELL
WOODS
DISPOSAL AREA BOUNDARY
© GROUNDWATER MONITORING
POINT
(S) SURFACE WATER MONITORING
POINT
SURFACE WATER DRAINAGE
SYSTEM
l_Bj SILTATION BASIN
Miiiiiiimn GAS CONTROL/VENTING
TRENCHES
[23 OPERATIONAL FACILITIES
*u DISPOSAL TRENCHES
5-11
-------
2. Sludge-only area fill
a. area fill mound
b. area fill layer
c. diked containment
3. Codisposal
a. sludge/refuse mixture
b. sludge/soil mixture
As shown in Table 3-7, the most significant features affecting method
selection are:
1. Sludge percent solids
2. Sludge characteristics (stabilized or unstabilized)
3. Hydrogeology (deep or shallow groundwater and bedrock)
4. Ground slopes
Having chosen a site (Chapter 4) and a landfill ing method (Chapter 3)
appropriate to that site, a suitable design must be established.
Sections 5.5, 5.6, and 5.7 discuss considerations that are relevant to
trench, area fill, and codisposal landfills respectively. In addition,
Chapter 10, Design Examples, provides an illustration of how a
landfill ing method is selected for a given site.
5.5 Sludge-Only Trench Designs
In a sludge-only trench operation, sludge is placed entirely below the
original ground surface. Sludge is usually dumped directly into trenches
from haul vehicles. On-site equipment is used only to excavate trenches
and apply cover; equipment does not usually come into contact with the
sludge.
Sludge-only trenches have been further classified into narrow trenches
and wide trenches. If one of these landfill ing methods has been
selected, design of the filling area consists primarily of determining
the following parameters:
1. Excavation depth
2. Spacing
3. Width
4. Length
5. Orientation
6. SI udge fill depth
7. Cover thickness
5-12
-------
A methodology for determining these parameters is included below in Table
5-5.
TABLE 5-5
DESIGN CONSIDERATIONS FOR SLUDGE-ONLY TRENCHES
Design Parameter
Determining Factor
Consideration
Excavation Depth
Spacing
Width
Length
Orientation
Depth to groundwater
Depth to bedrock
Soil permeability
Cation exchange capacity
of soil
Equipment limitations
Sidewall stability
Sidewall stability
Soil stockpiles
Vehicle access
Sludge solids content
Equipment limitations
Equipment efficiencies
Sludge solids content
Ground slopes
Land availability
Ground slopes
Sufficient thickness of soil must be maintained between trench
bottom and groundwater or bedrock. Required minimum separation
varies from 2 to 5 ft. Larger separations may be required for
higher than normal soil permeabilities or sludge loading rates.
Normal excavating equipment can excavate efficiently to depths
of 10 ft. Depths from 10 to 20 ft are less efficient opera-
tions for normal equipment; larger equipment may be required.
Depths over 20 ft are not usually possible.
Sidewal 1 st bility determines maximum depth of trench. If haul
vehicles are to dump sludge into trench from above, straight
sidewall should be employed. Tests should be performed at site
with a loaded haul vehicle to ensure that sidewall height as
designed will not collapse under operating conditions.
Trench spacing is determined by sidewall stability. Greater
trench spacing will be required when additional sidewall
stability is required. As a general rule, 1.0 to 1.5 ft of
spacing should be allowed between trenches for every 1 ft of
trench depth.
Sufficient space should be maintained between trenches for
placement of trench spoil stockpiled for cover as well as to
allow access and free movement by haul vehicles and operating
equipment.
Widths of 2 to 3 ft for typical sludge with solids content from
15 to 20%. Widths of more than 3 ft for typical sludge wit*i
solids content more than 201. Certain sludge (e.g., polymer
treated) may require higher solids contents before these
widths can apply.
Widths up to 10 ft for typical equipment (such as front end
loader) based on solid ground alongside trench. Widths up
to 40 ft for some equipment (such as a dragline) based on
solid ground. Unlimited widths for cover applied by equipment
(such as bulldozers) which proceed out over sludge.
Trenching machine
Backhoe
Excavator
Track dozer
Track loader
Dragline
Scraper
Typical Widths
2 ft
2-6 ft
4-22 ft
_>10 ft
MO ft
_>40 ft
>20 ft
If sludge solids are low and/or trench bottoms not level,
trench should be discontinued or dikes placed inside trench to
contain sludge in one area and prevent it from flowing over
large area.
Trenches should be parallel to optimize land utilization.
For low solids sludge, axis of each trench should be parallel
to topographic contours to maintain constant bottom elevation
within each trench and prevent sludge from flowing. With
higher solids sludge, this requirement is not necessary.
5-13
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TABLE 5-5 (Continued)
Design Parameter
Sludge fill depth
Cover thickness
Determining Factor
Trench width
Cover application method
Trench width
Cover application method
Trench width
2-3 ft
> 3 ft
TlO ft
Trench width
2-3 ft
> 3 ft
TlO ft
Consideration
Cover appl ication
method
Land-based equipment
Land-based equipment
Sludge-based equipment
Cover appl ication
method
Land-based equipment
Land-based equipment
Sludge-based equipment
Minimum distance
from top
1-2 ft
3 ft
4 ft
Cover
thickness
2-3 ft
3-4 ft
4-5 ft
1 ft = 0.305 m
Trench spacing is perhaps the most important and yet most difficult
design parameter to determine. Trench spacing is defined as the width
of solid undisturbed ground which is maintained between adjacent
trenches. Generally, trench spacing should be as small as possible to
optimize land utilization rates. However, the trench spacing must be
sufficient to resist sidewall cave-in. Failure of the trench sidewalls
is a safety hazard and reduces the volume of the trench available for
disposal. Factors to consider in determining trench spacing include:
(1) the weight of the excavating machinery, (2) the bearing capacity of
the soil (which is a factor of soil cohesion, density, and compaction),
(3) saturation level of the soil (which may be significantly influenced
by the moisture content of the sludge deposited), (4) the depth of the
trench, and (5) soil stockpiling and cover placement procedure.
A test which is used primarily to determine the adequacy of soils in
highway construction provides general guidance in determining trench con-
figurations (spacing and depth). This test determines the stability of a
soil by means of the Hveem stabilometer, which measures the transmitted
horizontal pressure due to a vertical load. The stability, expressed as
the resistance value (R), represents the shear resistance to plastic de-
formation of a saturated soil at a given density [3]. This test is
described under AASHO TUB (American Association of State Highway
Officials).
A general rule of thumb to follow in establishing trench spacing is that
for every 1 ft (0.3 m) of trench depth, there should be 1 to 1.5 ft (0.3
to 0.5 m) of space between trenches. If large inter-trench spaces are
not practical, the problem of sidewall instability may be relieved by
utilizing one of the four trench sidewall variations shown in Figure 5-2.
In any event, test cell trenches should be used to determine the
operational feasibility of any trench design. Such tests should be
5-14
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FIGURE 5-2
TRENCH SIDEWALL VARIATIONS
TYPE I
TYPE 2
TYPE 3
TYPE 4
performed by excavating adjacent trenches to the specified depth, width,
and spacing. A haul vehicle fully loaded with sludge should then back up
to the trench to determine if the sidewall stability is sufficient.
Using the considerations included in Table 5-5, design parameters can be
determined for a variety of sludge and site conditions. These considera-
tions have been employed to develop some alternative design scenarios for
trenches shown in Table 5-6. In some cases, sludge and site conditions
may indicate that it is wholly appropriate to utilize all of the design
parameters shown in one of these trench scenarios for application to a
real world situation. However, because of the great variety of sludge
and site conditions and their combinations, some adaptation of one of
these scenarios will be necessary in m ost ases. In any event, design
parameters should not be merely extracted from these tables; parameters
should always be well-considered and tested before full-scale
application. An example of a trench design (which utilizes these tables
initially, followed by engineering investigation and field testing) has
been included in Chapter 10, Design Examples.
5.5.1 Narrow Trench
Narrow trenches have widths less than 10 ft (3.0 m) and usually receive
low solids sludge with solids contents as low as 15%. Excavation and
cover application in narrow trench operations is via equipment based on
solid ground alongside the trench. Illustrations of typical narrow
trench operations are included as Figures 5-3 and 5-4.
The method of sludge placement in a narrow trench is dependent upon the
type of haul vehicle and upon trench sidewall stability. Usually trench
sidewalls are sufficiently stable and sludge may be dumped from the haul
5-15
-------
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5-16
-------
FIGURE 5-3
CROSS-SECTION OF TYPICAL NARROW TRENCH OPERATION
FIGURE 5-4
NARROW TRENCH OPERATION
5-17
-------
vehicle directly into trenches. However, if sidewalls are not
sufficiently stable, the sludge may be delivered to the trench in a
chute-extension similar to that found on concrete trucks or pumped in via
portable pumps. In some cases (particularly in wet weather) it may be
necessary to dump the sludge on solid ground near the trench and have
on-site equipment push the sludge into the trench.
5.5.2 Wide Trench
Wide trenches have widths greater than 10 ft (3.0 m) and usually receive
higher solids sludge with solids contents of 20% and more. Excavation of
wide trenches is usually via equipment which enters the trench itself.
Cover application may be by equipment based on solid ground alongside the
trench, but is usually accomplished by equipment that proceeds out over
the sludge spreading a layer of cover soil before it. Illustrations of
typical wide trench operations are included as Figures 5-5 and 5-6.
FIGURE 5-5
WIDE TRENCH OPERATION
5-18
-------
FIGURE 5-6
CROSS-SECTION OF TYPICAL WIDE TRENCH OPERATION
EXCAVATED
DEPTH
6'
The method of sludge placement in wide trenches may be either (1) from
haul vehicles directly entering the trench and dumping sludge in 3 to 4
ft (0.9 to 1.2 m) high piles or (2) from haul vehicles parked at the top
of trench sidewalls and dumping sludge into the trench. For the first of
these two cases sludge should have a solids content of 32% or more to
ensure that the sludge will not slump and can be maintained in piles.
For the second of these cases, sludge should have a solids content less
than 32% to ensure that it will flow evenly throughout the trench and not
accumulate at the dumping location. Of course, when sludge is free-
flowing, some means will be needed to confine the sludge to specific
areas in a continuous trench. Dikes are often used for this purpose as
illustrated in Figure 5-7.
FIGURE 5-7
CROSS-SECTION OF WIDE TRENCH WITH DIKES
DEPTH
5-19
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5.6 Sludge-Only Area Fill Design
In a sludge-only area fill operation, sludge is usually placed entirely
above the original ground surface. The sludge as received is usually
mixed with soil to increase its effective solids content and stability.
Several consecutive lifts of this sludge/soil mixture are usually then
applied to the filling area. Soil may be applied for interim cover in
addition to its usual application for final cover. On-site equipment
usually does come into contact with the sludge while performing functions
of mixing the sludge with soil; transporting this mixture to the fill
area; mounding or layering this mixture; and spreading cover over the
mixture.
Sludge-only area fills have been further classified into area fill
mounds, area fill layers, and diked containments. If one of these
landfill ing methods has been selected, design of the filling area may
consist primarily of determining the following parameters:
1. Bulking ratio
2. Cover application procedure
3. Width (of diked containment)
4. Depth of each lift
5. Interim cover thickness
6. Number of lifts
7. Depth of total fill (of diked containment before final cover)
8. Final cover thickness
A methodology for determining these factors is included below in Table
5-7.
TABLE 5-7
DESIGN CONSIDERATIONS FOR SLUDGE-ONLY AREA FILLS
Design Parameter
Bulking ratio
Consideration
Method Solids Content
Area fill mound 20-28%
28-32%
> 32%
Area fill layer TS-20%
20-28%
28-32%
> 32%
Diked 70-28%
containment 28-32%
J> 32%
Method Solids Content
Bui king
Ratio
2 soil 1 si udge
1 soil 1 sludge
0.5 so 1 :1 slue*""
1 soil 1 sludge
0.5 soil :1 si udge
0.25 soil :1 sludge
Not required
0.5 soil :1 sludge
0.25 soil :1 si udge
Not required
Cover Application Procedure
Cover application
procedure
Area fill mound ^ 20%
Area fill layer ]> 15%
Diked 20-28%
containment > 28%
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment
5-20
-------
TABLE 5-7 (Continued)
Design Parameter
Consideration
Width (of diked
containment)
Cover Application Procedure Equipment Used Width
Land-based equipment
Sludge-based equipment
Dragline
Track dozer
£ 40 ft
Not limited
Method
Depth of each 1 ift
Interim cover
thickness
Number of 1ifts
Area fill mound
Area fill layer
Diked containment
Method
Area fill mound
Area fi11 1ayer
Diked containment
Sludge Solids
> 20%
15~-20%
>_ 20%
20-28%
>_ 28%
Cover Application
Procedure
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment
Lift Depth
6 ft
1 ft
2-3 ft
4-6 ft
6-10 ft
Interim Cover
Thickness
3 ft
0.5-1 ft
1-2 ft
2-3 ft
Method
Area fill mound
Area fill layer
Diked containment
Sludge Solids
Content
20-28%
> 28%
T 15%
> 20%
No. of Lifts
1 maximum
3 maximum
1-3 typical
1-3 typical
Depth of total
fill (of diked
containment before
final cover)
Final cover
thickness
Cover Application Procedure
Land-based equipment
Sludge-based equipment
Method
Area fill mound
Area fill layer
Diked containment
Depth of Total Fill
No higher than 3 ft
below top of dikes
No higher than 4 ft
below top of dikes
Cover Application
Procedure
Final Cover
Thickness
Sludge-based equipment 1 ft
Sludge-based equipment 1 ft
Land-based equipment 3-4 ft
Sludge-based equipment 4-5 ft
1 ft = 0.305 ft
Using the considerations included in Table 5-7, the design parameters can
be determined for a variety of sludge and site conditions. These
considerations have been employed to develop some alternative design
scenarios for area fills which were included earlier in Table 5-6. An
example of an area fill design (which utilizes these tables initially,
followed by investigation and testing) has been included in Chapter 10,
Design Examples.
5-21
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5.6.1 Area Fill Mound
At area fill mound operations, sludge/soil mixtures are stacked into
mounds approximately 6 ft (1.8 m) high. Cover soil is applied atop each
lift of mounds in a 3 ft (0.9 m) thickness. The cover thickness may be
increased to 5 ft (1.5 m) if additional mounds are applied atop the first
lift. Illustrations of typical mound operations are included as Figures
5-8 and 5-9.
FIGURE 5-8
CROSS-SECTION OF TYPICAL AREA FILL MOUND OPERATION
REMOVE FOR USE
AS SLUDGE BULKING
AGENT
FINAL COVER
FUTURE
DRAINAGE
DITCH
INTERMEDIATE COVER
(31 THICK)
LEACHATE CONTROL
SLUDGE/SOIL
MIXTURE
FIGURE 5-9
AREA FILL MOUND OPERATION
5-22
-------
Sludge as received at the landfill is usually mixed with a bulking agent.
The bulking agent absorbs excess moisture from the sludge and increases
its workability. The amount of soil needed to serve as an additional
bulking agent depends upon the solids content of the sludge. Generally
the soil requirements shown in Table 5-7 may serve as a guideline. Fine
sand appears to be the most suitable bulking agent because it can most
easily absorb the excess moisture from the sludge.
5.6.2 Area Fill Layer
At area fill layer operations, sludge/soil mixtures are spread evenly in
layers from 0.5 to 3 ft (0.15 to 0.9 m) thick. This layering usually
continues for a number of applications. Interim cover between
consecutive layers may be applied in 0.5 to 1 ft (0.5 to 0.3 m) thick
applications. Final cover should be at least 1 ft (0.3 m) thick. An
illustration of a typical area fill layer operation is included as Figure
5-10.
FIGURE 5-10
CROSS-SECTION OF TYPICAL AREA FILL LAYER OPERATION
REMOVE FOR USE
AS SLUDGE BULKING
AGENT •
INTERIM COVER
(0.5-1 THICK).
LEACHATE COLLECTION
FUTURE
DRAINAGE
DITCH
SLUDGE/SOIL MIXTURE
(3' THICK)
5.6.3 Diked Containment
At diked containment operations, earthen dikes are constructed to form a
containment area above the original ground surface. Dikes can be of
various heights, but require side slopes of at least 2:1 and possibly
3:1. A 15 ft (4.6 m) wide road, covered with gravel should be constructed
atop the dikes.
5-23
-------
Sludge may be either (1) mixed with soil bulking for subsequent transport
and dumping into the containment area by on-site equipment or (2) dumped
directly into the containment area by haul vehicles without bulking soil.
Large quantities of imported soil may be required to meet soil require-
ments for dike construction and bulking since diked containments are
often constructed in high groundwater areas.
Sludge is dumped into diked containments in lifts before the application
of interim cover. Often this interim cover is a highly permeable
drainage blanket which acts as a leachate collection system for sludge
moisture released from the sludge lift above. Final cover should be of a
less permeable nature and should be graded even with the top of the
dikes. An illustration of a typical diked containment operation is
included as Figure 5-11.
FIGURE 5-11
CROSS-SECTION OF TYPICAL DIKED CONTAINMENT OPERATION
MIN. OF 15' OR AS REQUIRED
FOR CONSTRUCTION EQUIPMENT
EXTEND TO PREVENT
DISCHARGE ON SLOPE
FACE
3
UPPER SLUDGE LAYER
MIDDLE DRAINAGE BLANKET
5.7 Codisposal Designs
Codisposal is defined as the receipt of sludge at a conventional landfill
receiving municipal refuse. Two methods of codisposal have been identi-
fied: (1) sludge/refuse mixture and (2) sludge/soil mixture. Design
considerations for codisposal landfills have been included in Table 5-8.
5-24
-------
TABLE 5-8
DESIGN CONSIDERATIONS FOR CODISPOSAL OPERATIONS
Design Parameter
Consideration
Method
Bui king
Agent
Sludge Sol ids
Content
Bui king
Ratio
Bui king Ratio
Sludge/refuse Refuse
mixture
Sludge/ soil Soil
mixture
3-101
10-17%
17-20%
> 20%
> 20%
7 tons refuse:! wet ton sludge
6 tons refuse:! wet ton sludge
5 tons refuse:! wet ton sludge
4 tons refuse.! wet ton sludge
I soil :1 sludge
1 ton = 0.907 Mg
This manual does not provide all details on the design of a refuse
landfill receiving sludge. Rather, only those design features which
distinguish refuse landfills receiving sludge from those not receiving
sludge are addressed. The EPA document, "Sanitary Landfill Design and
Operation" [4] should be consulted for information relating to design and
operation of a refuse landfill.
5.7.1 Sludge/Refuse Mixture
In a siudge/refuse mixture operation, sludge is delivered to the working
face of the landfill where it is mixed and buried with the refuse. Most
of the considerations relative to the receipt of sludge at refuse
landfills are operational. These problems and solutions are described in
Chapter 6, Operation. Nevertheless, some of the considerations require
planning and design solutions. These are described in this section.
The first problem encountered at codisposal sites is sludge handling
difficulty due to the liquid nature of sludge relative to refuse.
Difficulties include (1) the sludge is difficult to confine at the
working face since it will readily flow, and (2) equipment slips and
sometimes becomes stuck in the sludge while operating at the working
face. These difficulties can be minimized if proper planning is employed
to control the quantity of sludge received at the refuse landfill. Every
effort should be made not to exceed the absorptive capacity of the
refuse. Obviously, the maximum allowable sludge quantity will vary
depending largely on the quantity of refuse received and the solids
content of the sludge. Some suggested bulking ratios for si udge/refuse
mixtures at various sludge solids contents were included previously in
Table 5-8. In any event determinations should be made on a site-by-site
basis using test operations.
5-25
-------
A second planning and design consideration for sludge/refuse mixture
operations concerns leachate control. The impact of sludge receipt on
leachate is highly site-specific. Generally, increased leachate
quantities should be expected. Leachate control systems may have to be
designed or modified accordingly.
A third planning and design consideration is storage for sludge received
in off-hours. In many cases sludge is delivered around the clock,
whereas, refuse delivery is confined to certain hours. Sludge storage
facilities may have to be installed to contain sludge overnight or over
weekends until sufficient refuse bulking is delivered.
5.7.2 Sludge/Soil Mixture
In a sludge/soil mixture operation, sludge is mixed with soil and applied
as cover over completed refuse fill areas. Most of the considerations
associated with these operations are also of an operational nature and
are addressed in Chapter 6, Operation. However, at the planning and
design stage, an area must be reserved for sludge/soil mixing. This area
must be sufficiently sized and have sufficient soil available for sludge
bulking. Information on a suggested bulking ratio was included in Table
5-8. The soils in this area must also be adequate to protect the
groundwater.
5.8 Environmental Safeguards
Groundwater protection is the most difficult and costly environmental
control measure required at many sludge landfills. Additionally,
contamination of surface water must not be allowed. Other environmental
considerations are methane gas migration and accumulation in nearby
structures, odors, dust, vectors, and/or aesthetics. Presented below are
design concepts that minimize or prevent adverse environmental impacts
from leachate generation and methane gas migration. The other
environmental controls are discussed in Chapter 6, Operations, since
their control is more a function of operation than design.
5.8.1 Leachate Controls
Leachate can be generated simply from the excess moisture in the sludge
as received at the landfill. Rainfall on the surface of the fill area
can add a limited amount of water to the interred sludge. However, the
surface of the landfill should be sloped enough to cause most of the
5-26
-------
rainfall to drain. Other storm water runoff must be diverted around the
landfill, and the landfill must be located above historically high
groundwater elevations. These positive controls will minimize the
quantity of leachate to be generated. In dry areas where the rate of
evaporation is much higher than the precipitation, zero infilration can
result, thereby limiting the amount of leachate generated by the sludge.
Table 5-9 details the range of constituent concentrations in leachate at
sludge landfills. It should be emphasized that the leachate depends on
the nature of the sludge interred. Moreover, if the site has been
properly designed, these constituents can be effectively attenuated by
soils or collected and subsequently treated.
TABLE 5-9
RANGE OF CONSTITUENT CONCENTRATIONS
IN LEACHATE FROM SLUDGE LANDFILLS [5]
(in mg/1 unless otherwise indicated)
Constituent
Concentration
Constituent
Concentration
cl/l
so4
TOC
COD
Ca
Cd
Cr
Zn
20-600
1-430
100-15,000
100-24,000
10-2,100
0.001-0.2
0.01-50
0.01-36
Hg
Cu
Fe
Pb
TKN
Fecal
Col iform
Fecal
Streptococcus
0.0011-0.0002
0.02-37
10-350
0.1-10
100-3,600
2,400-24,000
MPN/100 ml
2,100-240,000
MPN/100 ml
Leachate may enter into the water system through essentially two
pathways:
1. Percolation of the leachate, laterally or vertically, through
soil into the groundwater aquifers (Figure 5-12)
2. Runoff of leachate outcroppings into surface waters
Careful site selection and attention to design considerations can prevent
or minimize leachate contamination of groundwater and surface water. The
control of leachate may be accomplished through:
5-27
-------
FIGURE 5-12
WATER BALANCE AT SLUDGE LANDFILL
I PRECIPITATION
I
EVAPOTRANSPIRATION
SURFACE
RUNOFF
'POSSIBLE GROUNDWATER CONTOURS
1. Natural conditions and attenuation
2. Imported soils or soil amendments used as liners and/or cover
3. Membrane liners
4. Collection and treatment
5.8.1.1 Natural Conditions and Attenuation
Leachate may be contained on-site due to natural hydrogeological and
topographic conditions or through use of man-made facilities. Hydro-
geological characteristics of the site affecting leachate containment are
primarily the hydraulic conductivity of the underlying strata and the
depth to usable groundwater.
5-28
-------
Contaminants in leachate can be attenuated when passing through soils by
physical-chemical , mechanical , and/or biological processes. The
mechanisms by which these processes are performed include:
1. Filtration 4. Chemical precipitation
2. Ion exchange 5. Biodegradation
3. Adsorption 6. Complexation
The properties of the soil environment that influence the extent to which
these mechanisms are operative [6][7] include:
1. Soil grain size 5. Eh
2. Organic content 6. Hydrous oxides
3. Cation exchange capacity 7. Fill lime content
4. pH
The relative importance of one property over another is not well
documented. It is likely to vary from one situation to the next [?].
For example, some studies indicate that the cation exchange capacity
(CEC) of clay minerals are the dominant removal mechanisms for some
substances (K, Nfy, Mg, Si, and Fe), while precipitation was observed
to be the principal attenuative mechanism for other substances (Pb, Cd,
Hg, and Zn) [9], Other studies have indicated that the following soil
properties are most useful in attenuating pollutants from soils [9]:
1. Clay content
2. Content of hydrous oxides, primarily iron oxides
3. pH and content of free lime
4. Surface area per unit weight of soil
In another study [10], clay minerals were ranked according to their at-
tenuating capacity. It was observed that montmorillonite attenuated
pollutants four times better than illite and five times better than
kaolinite. These ratios are nearly identical with the CEC for the three
clays (Table 5-10) [6].
5-29
-------
TABLE 5-10
ATTENUATION AND PERMEABILITY PROPERTIES OF CLAYS [6]
1
0
2
4
8
16
32
64
100
2
4
8
16
16
32
64
100
4
16
8
8
8
Material
Montmorillonite
Monttnorillonite
Montmorillonite
Montmorillonite
Montmorillonite
Montmoril lonite
Montmorillonite
Montmoril lonite
Kaol inite
Kaol mite
Kaol inite
Kaol inite
Kaolinite
Kaol inite
Kaolinite
Kaol inite
Illite
IlUte
Montmorillonite
+ 8 Kaolinite
Kaol inite
+ 8 lllite
Kaolinite
+ 8 Illite
+ 8 Montmoril lonite
Cation
exchange
capacity
meq/lOOg
0.0
1.7
3.3
6.8
13.3
27.3
50.7
79.5
0.2
0.5
1.0
2.2
.
4.3
8.2
15.1
0.7
2.7
7.6
2.8
9.2
Bulk
density
g/cm^
1.71
1.71
1.77
1.79
1.87
1.55
1.23
0.84
1.68
1.76
1.80
1.87
1.94
1.66
1.22
0.90
1.80
1.83
1.95
1.95
1.64
Initial
hydraulic .
conductivity
cm/sec
1.27E-03
9.45F-04
4.34E-04
4.70E-04
1.22E-05
1.27E-06
3.05E-07
7.26E-07
7.44E-04
4.78E-05
9.90E-04
2.86E-05
1.09E-Q6
2.40E-06
5.45E-07
2.98E-07
8.17E-04
2.68E-05
5.35E-07
1.48F-06
8.08F-06
Quartz sand added to make 100%
Exponential notation: E-03 means x
The individual chemical constituents of the leachate examined in this
study were ranked according to their degree of attenuation by the three
clays as follows:
Cl < COD < Na < NH4 < K < Mg < Si < Cd < Zn < Pb < Hg
In one of the previously mentioned studies [6], physical characteristics
of representative whole soils from the major soil series in the United
States were determined (Table 5-11). These data were correlated with the
attenuative capacity of each soil. Results from these studies indicate
that the clay content of a soil and the surface area per unit weight were
by far the best single predictors of a soil's attenuation properties
[9]. The relative rate of movement through the soil is also important in
site design. Again, clay soils exhibit the slowest movement. In studies
in Omaha, Nebraska, leachates travelled only 160 ft (50 m) in 58 years
[5] through a clay soil.
5-30
-------
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5-31
-------
Although the capacity of soils to attenuate leachate is a site selection
and design consideration, the long term effectiveness of the contaminant
removal processes is not verified. A soil that offers moderately low
permeability, a high clay content, high CEC, and relatively high pH
(>6.0), is preferred over soils composed of coarse-grained particles with
high permeabilities and low CEC values.
Information on soil properties can be obtained from several sources, but
the Soil Conservation Service (SCS) soil surveys are the primary source.
Well logs can also offer additional data on soils and geology. Soil
surveys will normally provide soil maps delineating the apparent boun-
daries of soil series with their surface texture. A written description
of each soil series provides limited information on chemical properties,
engineering applications, interpretive and management information,
slopes, drainage, erosion potentials, and general suitability for most
kinds of crops grown in the particular area. Additional information on
soil characteristics and information regarding the availability of soil
surveys can be obtained directly from the SCS. The SCS serves as the
coordinating agency for the National Cooperative Soil Survey, and as
such, cooperates with other government agencies, universities, and agri-
cultural extension services in obtaining and distributing soil survey
information [11]. For insufficient data and/or for site specific
verification, tests should be performed on site by experienced soil
scientists.
The methods of determining some of these various soil properties are
presented in Table 5-4. Others may be ascertained from any number of
texts [12][13][14],
5.8.1.2 Imported Soils and Soil Amendments
If clayey soil exists only on a part of the site or at certain depths,
these suitable soils can be selectively excavated and used to line the
sludge landfill. It is highly desirable to use on-site soils to the
maximum extent possible to save the cost of purchasing and hauling soils
to the site. However, if on-site soils and other conditions are not
adequate to contain leachate or attenuation is inadequate to protect
groundwater, soil permeabilities can be lowered by the addition of
imported clays or polymeric materials. Clay minerals such as montmoril-
lonite or bentonite and artificial soil amendments are available commer-
cially if sufficient quantities of natural clay are not present on site.
In areas of high rainfall, it will be necessary to incorporate leachate
collection systems into the design to prevent water from ponding.
5-32
-------
The basic procedure for incorporating permeability-reducing soil
additives follows [15]:
1. Select the most cost-effective soil additive. Determine the
rate of application of the additive. This rate is based on
characteristics of the existing soil (e.g., soil particle size
and void space). The amount of additive should be such that the
amended soil has a permeability of 10~6 to 10"? cm/sec.
Usually it is advisable to have an independent soil testing lab
identify the most cost effective soil amendment and mix, but the
proper mix can be determined empirically by taking core samples
and adding various mixes of soil amendments. The data may then
be plotted on a graph and the mixes required for the desired
permeability established. It is often useful to determine the
plasticity of the mix in addition to the permeability.
2. Prepare and grade the site. Remove all tree roots, branches,
rocks or other items that may penetrate the amended soil layer.
The bottom of the site should be graded to allow the leachate
to drain to a centralized collection point.
3. Apply the additive and disc it into the existing soil to a depth
of approximately 12 in. (30 cm). The depth of artificially
applied or amended soil liners is best determined on a case-by-
case basis to obtain a safe yet cost-effective design.
4. Compact the soil-additive mixture to assure a watertight barrier
through differential settlement.
5. Flood the area with water to completely saturate the amended
soil. Clayey materials are very impermeable to water movement
when moist but can develop cracks when dry. Thus, clay liners
must be kept moist prior to depositing sludge to ensure
integrity.
6. Cover the clay liner with a 12 in. (30 cm) layer of native soil
to protect it during the landfill ing operation.
5.8.1.3 Membrane Liners
The use of membrane liners for containment of leachate has received
attention in the literature [16][17][18][19][20], and may be practical
for application at area fill and wide trench operations. Liners should
be used when soil permeabilities or soil depths are not adequate to
protect the groundwater or when required by State regulations. It is
5-33
-------
preferable to use Jji situ soils whenever possible. However, when
available site conditions or laws dictate that a liner must be used, many
types of membrane and other thin layer liners are currently available, as
indicated in Table 5-12.
TABLE 5-12
LINERS FOR SLUDGE LANDFILLS [16]
Asphalt compositions
- Asphaltic concrete
- Hydraulic asphaltic concrete
- Preformed asphaltic panels laid on concrete surfaces
- Catalytically blown asphalt sprayed on soil
- Emulsified asphalt sprayed on soil or on fabric matting
- Soil asphalt mixtures
- Asphalt seals
Portland cement compositions
- Concrete with asphalt seals
- Soil cement with asphalt seals
Soil sealants
- Chemical (soil amendments)
- Lime
- Rubber and plastic latexes
- Penetrating polymeric emulsions
Liquid rubbers sprayed
- Rubber and plastic latexes
- Polyurethanes
Synthetic polymeric membranes
- Butyl rubber
- Ethylene propylene rubber (EPDM)
- Chlorosulfonated polyethylene (Hypalon)
- Chlorinated polyethylene (CPE)
- Polyvinylchloride (PVC)
- Polyethylene (PE)
Synthetic polymeric and asphaltic materials are the most common membrane
liners used for landfills. Factors to consider in selecting a liner
are:
1. Effectiveness (It appears that some materials may not be accept-
able for use with certain wastes [21]. Before selecting a liner,
pretesting or literature review should be performed.)
2. Cost, both acquisition and installation (Table 5-13)
3. Installation time
4. Durability
5-34
-------
TABLE 5-13
ESTIMATED COSTS FOR LANDFILL LINERS [16]
(Note: Figures presented are 1973 costs)
Item
Butyl rubber
Chlorinated polyethylene
(CPE)
Chlorosul fonated
polyethylene
Ethyl ene propylene
rubber (EPDM)
Neoprene
Polyethylene film
Polyvinyl chloride
Thickness ,
mils
31.3 (1/32")
20
20
46.9 (3/64")
62.5 (1/16")
10
20
Price of
roll goods
($/ydz)
$2.25
1.58
1.66
2.42
2.97
0.36
0.90
Installed
costa
($/yd2)
$3.25-$4.00
$2.43- 3.24
2.88- 3.06
2.65- 3.42
4.41- 5.40
0.90- 1.44
1.17- 2.16
Soil + Bentonite
9 Ib/yd^ (1 psf)
Soil cement
6 in. thick + sealer (2 coats--each
0.25 gal/yd^)
Soil asphalt
6 in. thick + sealer (2 coats--each
0.25 gal/yd^)
Asphalt concrete--Dense-graded paving
with sealer coat (Hot mix--4-in. thick)
Asphalt concrete-Hydraulic-
(Hot mix—4-in. thick)
Bituminous seal
(catalytically blown asphalt)
1 gal/yd^
Asphalt emulsion on mat
(Polypropylene mat sprayed with asphalt
emulsion)
$0.72
1.25
1.25
2.35- 3.25
3.00- 4.20
1.50- 2.00
(with earth cover)
1.26- 1.87
a Soil cover not included; membranes require some soil cover, cost of which can
range from $0.10 to $0.50/ycr per ft of depth
b Hypalon, with nylon scrim
0.454 kg
= 0.7646
1 Ib
1 ydj
1 gal = 3.785 L
1 in. = 2.54 cm
1 yd' = 0.8361 n
Since most area fill landfills extend over a relatively large
membrane liners usually must be spliced during field installation.
seam durability and the amount of overlap should be
membrane design. Design of a membrane/liner follows
procedures identified for clay barriers:
area,
Thus,
considered in
roughly the same
5-35
-------
1. Select a membrane based on the above noted considerations
(effectiveness, cost, installation time, and durability)
2. Prepare and grade the soil surface
3. Compact the soil surface
4. Install the liner
5. Cover the liner with at least 12 in. (30 cm) of porous soil. If
equipment is to be operated over the sludge or refuse is
disposed, more cover may be required
It should be noted that liners have potential disadvantages, including:
1. The expected life of liners has not been established. Liners
have been used at landfills over a relatively short period (less
than 10 yrs), whereas effectiveness must be assured for many
decades.
2. Sludge disposal operations can tear the liner, causing leachate
seepage.
3. Changes in the hydraulic conductivity of the underlying or sur-
rounding soil cause the groundwater to rise, which exerts upward
pressure on the liner.
4. Once the liner is in place and sludge is deposited, membrane
failure cannot be easily detected or readily repaired.
Changes in hydraulic conductivity and evaporation result when the area is
excavated and the overburden removed. The problems associated with a
rising water table can be mitigated by placing a leachate collection
system beneath liners. Although expensive, this will relieve pressure on
the liners and, if properly placed, enable the presence and locations of
leaks to be identified.
5.8.1.4 Collection and Treatment
If the site design includes provisions for leachate containment, a
leachate collection system must be installed. The collection system may
consist of a sump into which leachate collects and is subsequently pumped
to a holding tank or pond. Leachate may also be collected by a series
of drain pipes or tiles which intercept and channel the leachate to the
5-36
-------
surface or to a sump. Figure 5-13 depicts representative collection
systems. Groundwater interceptor trenches may be used to lower the water
table in the vicinity of the fill area (Figure 5-14).
FIGURE 5-13
UNDERDRAIN FOR LEACHATE COLLECTION
tf' CLAY
SLUDGE
6-l2"ORAVEL OR
,CRUSHED STONE
PERFORATED
PLASTIC PIPE
FIGURE 5-14
UPGRADIENT GROUNDWATER INTERCEPTOR TRENCH
NATURAL SOIL
MATERIAL
ORIGINAL
GROUNDWATER LEVEL
CUTOFF TRENCH
GROUNDWATER
5-37
-------
Collected leachate may be treated by one or more of the following
methods:
1. Discharge to a wastewater collection system or haul directly to a
treatment plant
a. biological treatment
b. physical-chemical treatment
2. Recycle through the landfill
3. Evaporation of leachate in collection ponds
4. On-site treatment
Depending on the leachate characteristics, volume, and local regulations,
it may be possible to discharge collected leachate to an existing waste-
water system for subsequent treatment with municipal wastewater. Local
wastewater treatment plant personnel should be consulted for leachate
acceptability to determine special requirements for discharge to the
treatment plant; e.g., large slugs of highly contaminated leachate may
have to be mixed with municipal wastewater to prevent plant upsets.
Leachate collected from relatively new landfills is best treated by
biological processes (Table 5-14) [22], Physical-chemical treatment
processes are most effective in treating leachate from landfills
containing stabilized sludge or in removing organic matter from sludge
from biological treatment units. Activated carbon and reverse osmosis
show promise for removing organic matter, but their viability on a large
scale over extended periods has not been verified.
TABLE 5-14
EXPECTED EFFICIENCIES OF ORGANIC REMOVAL FROM LEACHATE [22]
Character of
COD/
TOC
(mg/I)
>2.8
2.0-2.3
<2.0
BOO/
COD
(mg/1)
>0.5
0.1-0.5
<0.1
Leachate
Age of
fill
Young
(<5yr)
Med i urn
(5-10 yr)
Old
(<10yr)
Effectiveness of Treatment Processes
COD
(mg/1)
>10,000
500-10,000
<500
Biological
treatment
Good
Fair
Poor
Chemical
precipitation
(mass lime
dose)
Poor
Fair
Poor
Chemical
oxidation
Ca (CIO),
Poor
Fair
Fair
°7
Poor
Fair
Fair
5-38
-------
If discharge to the wastewater system is not practical or if the leachate
is potentially disruptive to treatment plant operations, on~site
treatment or transportation to a chemical waste disposal site will have
to be utilized.
On-site treatment may consist of recycling the leachate through the land-
fill, placing the leachate in a shallow basin to allow it to evaporate,
or installing a small (specially designed) treatment plant on site. The
latter alternative should be avoided if at all possible due to its high
cost and the unproven reliability of such small plants.
Leachate recycling has been shown to be useful because it [23]:
1. Promotes rapid development of anaerobic decomposition in the
wastes
2. Increases the rate and predictability of biological stabiliza-
tion
3. Reduces the volume of leachate to be handled by evaporation of
the water during dry periods
However, leachate recycling systems are not feasible at most sites;
specifically, areas with high rainfalls and high application rates are
not suitable. Its primary application should be restricted to codisposal
sites in climates where the evaporation rate exceeds rainfall to a
significant extent.
It may be valuable to have contingency plans designed to intercept a
downgradient leachate plume. Essentially this would consist of a number
of downgradient wells which could be pumped, thus containing the plume.
The extracted water may be treated and discharged.
5.8.2 Gas Controls
Gas is produced by the decomposition of organic matter in sludge. The
primary gases of decomposition are methane and carbon dioxide. Some
nitrogen and oxygen is found. Traces of ammonia, hydrogen sulfide,
hydrogen, and volatile organic species are sometimes found in landfills.
The amount and composition of gases produced depends on the quantity and
characteristics of sludge deposited, the amount of moisture present, and
other factors. Ranges of gas concentrations that may be expected are
shown in Table 5-15 [5].
5-39
-------
TABLE 5-15
GAS CONCENTRATIONS AT SELECTED SLUDGE LANDFILLS [5]
(% of sample)a
Sludge-Only Codisposal
CH4
co2
°2
N,
1
55
41
1
3
2
56
39
1
3
3
48
20
7
24
4
50
37
2
10
5
43
50
1
6
6
59
40
-
1
7
54
32
3
10
Totals may not add to 100 due to rounding.
The rate and types of gas generated depends on the type of microbial
(biological) decomposition occuring. The amount of gas generated from
sludge decomposition can be expected to range from 16 to 18 ft3/lb (1
to 1.1 mS/kg) of volatile matter reduced [24]. Five to 8 ft3/lb (0.3
to 0.5 m3/kg) of gas is generated from deposited municipal solid
waste). Raw sludges probably generate somewhere between 8 and 16
ft^/lb of dry solids. Digested sludges would be expected to generate
considerably less gas since most of this gas quantity was generated in
the digestors. Of course, for all the rates noted above (for refuse as
well as raw and digested sludges) it should be noted that the gas is
generated over an extended period that may exceed fifty years.
Methane, like carbon dioxide, is odorless; unlike carbon dioxide, methane
is relatively insoluble in water. However, when methane is present in
air at between 5 and 15% concentrations, and is confined in an enclosed
area, it may be explosive. Methane can move by diffusion through the
sludge into the atmosphere where it is harmlessly dissipated. The gas
can also move laterally from the landfill into surrounding soils,
especially if the cover material is relatively impermeable. Through
lateral movement, methane could seep into nearby buildings or utilities.
A build-up of methane to a concentration within the explosive limits is
hazardous. Migrating gas can also damage vegetation surrounding a sludge
landfill by excluding oxygen from the root zone [25][26]. The cover soil
can be used to control gas migration and odor from the sludge. Chapter
6 (Operation) and Chapter 8 (Completed Site) discuss in detail the proper
placement of cover soil.
Installation of gas control facilities is not necessary if the site is
isolated and will remain isolated from inhabited structures. However,
when inhabited structures are near the landfill, and monitoring wells
indicate that a structure is threatened, gas migration controls are
5-40
-------
required. Migration can be controlled by installing barriers to gas flow
and/or by collecting and venting the gas. Gas control techniques can
generally be classified into permeable and impermeable methods.
5.8.2.1 Permeable Methods
Permeable methods (Figure 5-15) usually entail installing a gravel-filled
trench outside the filled area. The trench intercepts migrating gas and
vents it into the atmosphere. A forced vacuum extraction system in
trenches or in wells is sometimes appropriate.
FIGURE 5-15
PERMEABLE METHOD OF GAS MIGRATION CONTROL
_- SLOPE,
5.8.2.2 Impermeable Methods
Placing a barrier of very low permeability material around the perimeter
of the landfill minimizes lateral gas migration. The movement of gas
through soils can be controlled by using materials that are more
impermeable than the surrounding soil.
The most common material used for construction of gas barriers is com-
pacted clay. A clay layer approximately 2 ft (0.6 m) thick is probably
adequate (if it can be constructed that thin). Often a thicker layer is
required in order to ensure an adequate seal if the sides!ope exceeds
5-41
-------
2H:1V. To be effective, the clay layer must be continuous; it cannot be
penetrated. The clay liner should be constructed as the fill progresses,
because prolonged exposure to air will dry the clay and cause it to
crack. Synthetic membranes may be considered for the control of
migrating gas but their effectiveness has not been established. PVC is
thought to be the most effective.
5.8.2.3 Gas Extraction Systems
An effective method of gas control in refuse landfills involves the
placement of an impermeable barrier combined with a gas extraction system
via strategically located forced exhaust vents. However, such systems
are not suitable for sludge landfills because the high moisture content
typically found in sludge does not permit gas movement and sludge can
enter and clog the evacuation pipes.
A few gas recovery systems have been installed at large refuse landfills
to recover methane gas. Gas recovery has not been attempted at sludge
landfills and is probably not feasible at this time; to be viable, the
landfill must be very large; e.g., more than 5,000,000 tons (450,000,000
Mg) for a refuse landfill. Sludge landfills are normally much smaller
than this.
5.9 Storm Water Management
All upland drainage should be collected and directed around the landfill.
Drainage may be channeled through the landfill via an enclosed pipe, but
only if absolutely necessary. The drainage channels may be constructed
of earth (Figure 5-16), corrugated metal pipe (CMP) (Figure 5-17),
gunite-lined earthen ditches, or stone-lined ditches (Figure 5-18).
If the access or on-site roads of the landfill are paved, they may be
used to channel drainage across a landfill. It is important to note that
the dimensions shown are representative. Actual dimensions for con-
structing drainage structures should be based on on-site investigations
of runoff potential.
On the sludge landfill itself, all active and completed site working
areas should be properly graded. The surface grade should be greater
than 2% to promote runoff and inhibit ponding of precipitation, but less
than 5% to reduce flow velocities and minimize soil erosion. If
necessary, siltation ponds should be constructed to settle the solids
contained in the runoff from the site. Straw bales, berms, and
vegetation may supplement ponds or be used in conjunction with them to
5-42
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FIGURE 5-16
EARTHEN DRAINAGE CHANNEL
VARIES
2M MAX
NATURAL
GROUND
1/2 OR 2
SLOPE
VARIES
l' MIN.
FIGURE 5-17
CMP DRAINAGE CHANNEL
VARIES
18" MIN.
^ CMP CHANNEL
NATURAL GROUND
5-43
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FIGURE 5-18
STONE DRAINAGE CHANNELS
SOD ENTIRE WIDTH
SODDED WATERWAY
W
4-12 STONE
WATERWAY WITH STONE
CENTER DRAIN
control runoff and siltation on the site. Since the location of fil]
areas is constantly changing, portable drainage structures may be more
economical than permanent facilities.
5.10 Access Roads
As a minimum, a permanent road should be provided from the public road
system to the site. For larger landfills, the roadway should be 20 to 24
ft (6 to 7 m) wide for two-way traffic. For smaller operations a 15 ft
(5 m) wide road can suffice. As a minimum, the roadway should be gravel-
surfaced in order to provide access regardless of weather conditions.
Grades should not exceed equipment limitations. For loaded vehicles,
most uphill grades should be less than 7% and downhill grades less than
10%.
5-44
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Temporary roads are used to deliver the sludge to the working area from
the permanent road system. Temporary roads may be constructed by
compacting the natural soil present and by controlling drainage, or by
topping them with a layer of gravel, crushed stone, cinders, crushed
concrete, mortar, bricks, lime, cement, or asphalt binders to make the
roads more serviceable.
5.11 Other Design Features
5.11.1 Soil Availability
The quantity and adequacy of on-site soil for use as a bulking agent and
for covering sludge will have been determined during the site selection
process. However, the logistics of soil excavation, stockpiling, and
consumption are more thoroughly evaluated during design. Excavation and
stockpiling of soil must be closely coordinated with soil use for the
following reasons:
1. Soil determined to be suitable for use and readily excavated may
be located in selected areas of the site. The excavation plan
should designate that these areas be excavated before filling has
proceeded atop them.
2. Accelerated excavating programs may be desirable during warm
weather to prevent the need to excavate frozen soil during cold
weather.
3. Soil stockpiles should be located so that runoff will not be
directed into future adjacent excavations and/or sludge filling
areas and to minimize erosion.
5.11.2 Special Working Areas
Special working areas should be designated on the site plan for inclement
weather or other contingency situations. Access roads to these areas
should be of all-weather construction and the area kept grubbed and
graded. Arrangements for special working areas may include locating such
areas closer to the landfill entrance gate (see Figure 5-19).
5.11.3 Buildings and Structures
At larger sludge landfills or where climates are extreme, a building
should be provided for office space and employee facilities. Since
5-45
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FIGURE 5-19
SPECIAL WORKING AREA
V
DRY WEATHER OPERATIONAL
AREA
PUBLIC ROAD
sludge landfills operate year round, regardless of weather, some
protection from the elements should be provided for the employees.
Sanitary facilities should be provided for both landfill and hauling
personnel. At a few of the largest landfills, a building might be
provided for equipment storage and maintenance. At smaller landfills,
buildings cannot be justified, but trailers may be warranted.
Buildings on sites that will
temporary, mobile structures.
should consider gas movement
decomposing sludge.
be used for less than 10 years can be
The design and location of all structures
and differential settlement caused by
Scales are seldom used at sludge landfills. Normally, a relatively
accurate estimate of fill quantities is available from the wastewater
treatment plant(s) that generate the sludge.
5-46
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5.11.4 Utilities
Larger landfills should have electrical, water, communication, and
sanitary services. Remote sites may have to extend existing services or
use acceptable substitutes. Portable chemical toilets can be used to
avoid the high cost of extending sewer lines; potable water may be
trucked in; and an electric generator may be used instead of having power
lines run into the site.
Water should be available for drinking, dust control, washing mud from
haul vehicles before entering the public road, and employee sanitary
facilities. A sewer line may be desirable, especially at large sites and
at those where leachate is collected and treated with domestic waste-
water. Telephone or radio communications may be necessary since
accidents or spills can occur that necessitate the ability to respond to
call s for assistance.
5.11.5 Fencing
Access to landfills should be limited to one or two entrances that have
gates that can be locked when the site is unattended. Depending on the
topography and vegetation on the site and adjoining areas, entrance gates
may suffice to prevent unauthorized vehicular access. At some sites it
is desirable to construct periphery fences to keep out any trespassers
and animals, which is an especially important consideration.
Fencing requirements will be greatly influenced by the relative isolation
of the site. Sites close to housing developments may require fencing
to keep out children and to provide a visual screen for the landfill.
Landfills that are in relatively isolated rural areas may require a less
sophisticated type of fencing or only fencing at the entrance and other
places to keep out unauthorized vehicles.
If vandalism and trespassing are to be discouraged, a 6-ft (1.8-m) high
chain link fence topped with a barbed wire guard is desirable (although
expensive). A wood fence or a hedge may be used to screen the operation
from view. A 4-ft (1.2-m) high barbed wire fence will keep cattle or
sheep off the site. Keeping trespassers and ajiimals off sludge landfills
is more important than for refuse landfills because the sludge may not be
sufficiently stable to support their weight.
If the sludge is being disposed of at a refuse landfill the fencing will
also contain litter to some degree.
5-47
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5.11.6 Lighting
If dumping operations occur at night, portable lighting should be
prpvided at the operating area. Alternatively, lights may be affixed to
haul vehicles and on-site equipment. These lights should be situated to
provide illumination to areas not covered by the regular headlights of
the vehicle.
If the landfill has structures (employee facilities, administrative of-
fices, equipment repair or storage sheds, etc.), or if there is an access
road in continuous use, permanent security lighting might be desirable.
5.11.7 Wash Rack
For landfills where operational procedures call for frequent contact of
equipment with the sludge, a cleaning program should be implemented.
Portable steam cleaning units or high pressure washers may be used. A
curbed wash pad and collection basin may be constructed to collect and
contain contaminated wash water. The contaminated water may be either
pumped to a septic tank/soil absorption system or dispersed with the
sludge. The washing facility should be used to clean mud from haul
vehicles, to keep sludge and mud off the highway.
5.12 References
1. Proposed Classification Criteria for Solid Waste Disposal Facilities.
Part II. U.S. Environmental Protection Agency. Federal Register.
February 6, 1978.
2. Draft Environmental Impact Statement, Appendices, Proposed Regula-
tion, Criteria for Classification of Solid Waste Disposal Facilities.
Office of Solid Waste, U.S. Environmental Protection Agency. April
1978.
3. Portland Cement Association. PCA Soil Primer. Portland Cement
Association, Chicago, IL. 1962.
4. Brunner, D. R. and D. J. Keller. Sanitary Landfill Design and Opera-
tion. U.S. Environmental Protection Agency. Report No. SW-65ts.
1972.
5. SCS Engineers. Selection and Monitoring of Sewage Sludge Burial Case
Study Sites.
5-48
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6. Fuller, W. H. and N. Korte. Attenuation Mechanisms of Pollutants
Through Soils. In: Gas and Leachate from Landfills, Formation,
Collection, and Treatment. Report No. EPA 600/9-76-004. 1976.
7. Farquhar, G. J. and F. A. Rovers. Leachate Attenuation in Undis-
turbed and Remolded Soils. In: Gas and Leachate from Landfills
Formation, Collection, and Treatment. Report No. EPA 600/9-76-004.
1976.
8. Farquhar, G. J. Leachate Treatment by Soil Methods. J_n: Management
of Gas and Leachate in Landfills. Proceedings of the Third Annual
Municipal Solid Waste Research Symposium. Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency. Report
No. EPA 600/9-77-026. September 1977.
9. Roulier, M. H. Attenuation of Leachate Pollutants by Soils. In:
Management of Gas and Leachate in Landfills. Proceedings of the
Third Annual Municipal Solid Waste Research Symposium. Municipal
Environmental Research Laboratory, U.S. Environmental Protection
Agency. Report No. EPA 600/9-77-026. September 1977.
10. Griffin, R. A. and N. F. Shimp. Leachate Migration Through Selected
Clays. In: Gas and Leachate from Landfills, Formation, Collection,
and Treatment. Report No. EPA 600/9-76-004. 1976.
11. Process Design Manual for Land Treatment of Wastewater. U.S. En-
vironmental Protection Agency. Technology Transfer. Report No. EPA
625/1-77-008. 1977.
12. Block, C. A. (ed.) Methods of Soil Analysis. American Society of
Agronomy, Madison, WI. 1965.
13. Soil Conservation Service. Soil Survey Laboratory Methods and
Procedures for Collecting Soil Samples. Soil Survey Investigations
Report 1 (Revised). Washington, D.C. U.S. Government Printing
Office. 1965.
14. Walsh, L. M. and J. D. Beaton (eds.) Soil Testing and Plant Analysis
(Revised). Soil Science Society of America, Madison, WI. 1973.
15. American Colloid Company. Use of Bentonite as a Soil Sealant for
Leachate Control in Sanitary Landfills, Skokie, IL. 1975.
16. Haxo, H.E., Jr. Assessing Synthetic and Admixed Materials for Lining
Landfills: Formation, Collection, and Treatment. In: Gas and
Leachate from Landfills. Report No. EPA 600/9-76-004. 1976.
17. Haxo, H.E., Jr. Evaluation of Selected Liners When Exposed to
Hazardous Wastes. In: Proceedings of Hazardous Waste Research
Symposium, Tuscon, AZ. Report No. EPA 600/9-76-015. 1976.
5-49
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18. Geswein, A.J. Liners for Land Disposal Sites - An Assessment. U.S.
Environmental Protection Agency. Report No. SW-137. 1975.
19. Gulf South Research Institute. Preventing Landfill Leachate
Contamination of Water. U.S. Environmental Protection Agency.
Report No. EPA 670/2-73-021. 1973.
20. Haxo, H.E., Jr. Compatibility of Liners with Leachates. In:
Management of Gas and Leachate from Landfills. Proceedings of ~th~e
Third Annual Municipal Solid Waste Research Symposium. Municipal
Environmental Research Laboratory, U.S. Environmental Protection
Agency. Report No. EPA 600/9-77-026.
21. Haxo, H.E., Jr., R.S. Haxo, and R.M. White. Liner Materials Exposed
to Hazardous and Toxic Sludges, First Interim Report. Municipal
Environmental Research Laboratory, U.S. Environmental Protection
Agency. Report No. EPA 600/2-77-081. June 1977.
22. Chi an, E.S.K. and F. DeWalle. Sanitary Landfill Leachates and Their
Treatment. Journal of the Environmental Engineering Division.
Volume 102, No. EE2. April 1976.
23. Pohland, F.G. Landfill Management with Leachate Recycle and
Treatment: An Overview. In: Gas and Leachate from Landfills.
Report No. EPA 600/9-76-004. 1976.
24. Clark, J.W. and W. Viessman, Jr. Water Supply and Pollution Control.
International Textbook Co., Scranton, PA. 1965.
25. Flower, F.B. Case History of Landfill Gas Movement Through Soils.
In: Gas and Leachate From Landfills. Report No. EPA 600/9-76-004.
T976.
26. Flower, F.B., E.A. Leone, E.F. Gilman, and J.J. Arthur. Vegetation
Kills in Landfill Environs. In: Management of Gas and Leachate in
Landfills. Proceedings of tn~e Third Annual Municipal Solid Waste
Research Symposium. Municipal Environmental Protection Agency.
Report No. EPA 600/9-77-026. September 1977.
5-50
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CHAPTER 6
OPERATION
6.1 Purpose and Scope
The purpose of this chapter is to introduce an approach for implementing
the design plans into an effective sludge landfill operation. The opera-
tion of a sludge landfill can be viewed as an ongoing construction pro-
ject. As with any construction project, it must proceed according to
detailed plans. Unlike conventional construction, however, the operating
parameters of a sludge landfill are often changing and may require
innovative alterations and contingency plans. An effective operation
requires a detailed operational plan and a choice of equipment compatible
with the sludge characteristics, the site conditions, and the landfill ing
method.
For the purposes of this chapter, the site operation may be viewed in two
parts: the first part concerns operational procedures that are specific
to the landfill ing method; the second part concerns general operational
procedures that are independent of the landfill ing method.
6.2 Method-Specific Operational Procedures
Procedures dependent on the landfill ing method include:
1. Site preparation
2. Sludge unloading
3. Sludge handling and covering
Because these procedures vary for each landfill ing method, they will be
discussed as functions of the landfill ing methods introduced in Chapter
3.
6.2.1 Sludge-Only Trench
For sludge-only trenches, subsurface excavation is required so that
sludge can be placed entirely below the original ground surface. In
trench applications, the sludge is usually dumped directly into the
trench from haul vehicles. Soil is not used as a sludge bulking agent.
Soil is used as cover, usually in a single, final application.
6-1
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Two kinds of sludge-only trenches have been identified including (1)
narrow trench and (2) wide trench. Narrow trenches have widths less than
10 ft (3.0 m). Wide trenches have widths greater than 10 ft (3.0 m).
Chapter 3 (Sludge Characteristics and Landfill ing Methods) and Chapter 5
(Design) should be consulted for specific design criteria.
6.2.1.1 Site Preparation
Site preparation includes all tasks which are required prior to the
receipt of sludge. Tasks include clearing and grubbing, grading the
site, constructing access roads, and excavating trenches.
The location of access roads depends on the topography and the land
utilization rate. Narrow trenches use land rapidly and require more
extensive road construction. Wider and/or longer trenches may require
vehicle access roads along both sides of the trench.
Prior to grading, the area should be cleared and grubbed. Grading should
be done on the site (1) to control runoff and (2) to provide grades com-
patible with equipment to be used. For example, drag lines and trenching
machines operate more efficiently on level surfaces. Narrow trenches may
require less grading due to their applicability to hilly terrain.
Progressive trench construction is the most efficient procedure for a
narrow trench operation. The initial trench is constructed using appro-
ri m n -»4-^s j-i A-. I i 4 r^m f\**+ -\ »^^l 4- L%v\ r«rt 4 1 ^N^^k<"»i/« ill r% 4 1 r\s4 -»T ^\ w»rt -^Irtrt 1 Onfl "^ h Ol t M O
;d to ground
... _ ,..._. ... ..._ ......... .. .... and used to
prevent runoff from entering the trench. Succeeding trenches are
constructed parallel to the initial trench. The trench dimensions and
the distance between the trenches should follow design specificiations.
narrow trench operation. The initial trench is constructed us
priate equipment and the soil either (1) piled along the leng
trench, or (2) stockpiled in a designated area, or (3) graded
level. Soil is often piled on the uphill side of the trench ai
nrp\/pnt rimn-ff fVnm pntprinn thp tremrh. ^nrrppHinn trp
Trenches may require dikes positioned intermittently across the width of
the trench, especially if such trenches are long. The dikes should be of
sufficient height to contain the sludge and attendant liquids and allow
proper trench filling and covering. Equipment may be used inside wide
trenches to construct dikes.
On-going site preparation is critical for proper execution of a trenching
operation. Depending on the quantity of sludge received, a designated
trench volume should always be maintained in advance of filling
operations. Ideally, trenches should be prepared at least one week ahead
of the current landfill ing operation.
6-2
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6.2.1.2 Sludge Unloading
Signs should be placed to designate which trench is in use. Sludge is
usually unloaded from haul vehicles via direct dumping. However, metal
extension chutes or pumping may also be employed. If direct dumping is
employed, an appropriately sized area should be prepared at the lip of
the trench so that transport vehicles can safely back up to the trench
edge for unloading. Sludge unloading can occur along the length of both
sides of the trench if necessary. The entire unloading area should be
kept clear of discharged sludge and periodically regraded to facilitate
safe unloading operations.
6.2.1.3 Sludge Handling and Covering
Sludge should be uniformly distributed throughout the trench. Otherwise,
depressions that could cause ponding are likely to occur as the fill
settles. Narrow and wide trenches should be filled only to a level where
a sludge overflow will not occur due to displacement during cover
application. Markers on trench sidewalls can be used for this purpose.
The appropriate level for sludge filling can best be established via
experimentation using test loads.
Concurrent excavation, filling, and covering of trenches is a sequential
operation that requires a coordination of effort. When the sludge has
filled the trench to the designated level, cover material should be
applied using either soil freshly excavated from a parallel trench or
soil stockpiled during excavation of the trench being filled. Depending
upon the solids content of the sludge and the width of the trench, cover
application should proceed as follows:
1. If the sludge has a solids content from 15 to 20%, the width of
the trench should be 2 or 3 ft (0.6 to 0.9 m). Cover applica-
tion should be via equipment based on solid ground adjacent to
the trench. Covering equipment may include a backhoe with
loader, excavator, or trenching machine.
2. If the sludge has a solids content from 20 to 28%, the width of
the trench is technically unlimited. However, it is limited by
the requirement that cover be applied by equipment based on
solid ground. Covering equipment may include a backhoe with
loader, excavator, track loader, or dragline.
6-3
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3. If the sludge has a solids content of 28% or above, the width of
the trench is unlimited. Cover application can be via equipment
which proceeds out over the trench pushing cover over the
sludge. Covering equipment usually is a track dozer.
In all cases, initial layers of cover should be carefully applied to
minimize sludge displacement. The final cover should extend at least 1
ft (0.3 m) above the ground surface (and preferably more). As settling
occurs, additional soil cover may have to be applied to prevent
depressions and ponding. Experience has shown that the majority of
settlement occurs within 6 to 9 months. After it has settled, the entire
trenched area should be graded. The trench areas should be sloped to
minimize infiltration and prevent ponding. If practical, an impermeable
cover (clay, etc.) should be applied to reduce infiltration. Final
covers may include 1 to 2 ft (0.3 to 0.6 m) of topsoil and suitable
vegetation such as grasses. A sludge soil mixture of 2 to 10 parts soil
to 1 part sludge can be used to enrich the soil if necessary.
6.2.1.4 Operational Schematics
The preceding information has been included to generally describe the
operation of trenches. Figures 6-1 through 6-4 illustrate specific
trench operations.
6.2.2 Sludge-Only Area Fill
For sludge-only area fills, sludge is usually placed above the original
ground surface. In area fill applications, soil is usually mixed with
the sludge as a bulking agent. Cover may be used in both interim and
final applications.
Three kinds of sludge-only area fills have been defined including (1)
area fill mound, (2) area fill layer, and (3) diked containment. In area
fill mound operations, sludge/soil mixtures are usually stacked into
piles approximately 6 ft (1.8 m) high. In area fill layer operations,
sludge/soil mixtures are spread evenly in layers 0.5 to 3 ft (0.15 to 0.9
m) thick. In diked containment operations, sludge (with or without
bulking soil) is dumped into pits contained by dikes constructed above
the ground surface. Chapters 3 and 5 should be consulted for specific
design criteria.
6-4
-------
FIGURE 6-1
NARROW TRENCH OPERATION
A sludge landfill in Paris, Maine receives 55 wet tons (50 Mg) per
day of stabilized 14% solids sludge. Trenches at the site are 6 ft
(1.8 m) wide and 6 to 8 ft (1.8 to 2.4 m) deep. From 4 to 10 ft (1.2
to 3.0 m) of undisturbed ground is maintained between trenches.
Sludge is off-loaded directly into trenches from load-lugger trucks
with arm-extended dump buckets. Unloading occurs either at the end
of the trench or along its length. The sludge is filled to within 2
ft (0.6 m) of the surface and allowed to settle for several days
before the trench is covered. This is necessary because the low
solids sludge will not support cover initially. Since the sludge is
stabilized, odor is not a serious problem. In warm weather, lime is
applied over the surface of the sludge layer.
While the sludge unloading is occurring in one location, trench
excavation and sludge covering are being conducted in other areas.
Sludge-filled trenches are covered with soil taken from newly
excavated trenches. The sludge-filled trench is covered carefully in
order to prevent the displacement of sludge by the soil cover.
Covering the si udge-filled trench in this manner produces rugged
mounds 5 to 6 ft (1.5 to 1.8 m) high throughout the area. The
trenches are then allowed to settle for several months before the
area is regraded to a smooth surface.
6-5
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FIGURE 6-2
WIDE TRENCH OPERATION AT REFUSE LANDFILL
This trench operation is located on a 100-acre (40-ha) refuse land-
fill site near Greenville, Michigan. A single wide trench 300 ft (90
m) long, 30 ft (9 m) wide, and 15 ft (4.6 m) deep is employed to dis-
pose of approximately 25 yd3 (19 m3) of anaerobically digested
and dewatered sludge each day. The trench is constructed using one
excavator equipped with a 36 in. (91 cm) wide bucket. Dump trucks
unload the 15% solids sludge at the edge of the trench, starting at
one end and moving forward as the trench is filled.
The trench filling operation takes approximately 6 to 8 months, in
which time the sludge dewaters through the sandy soil. By the time
the trench is totally filled, the old sludge at one end of the trench
is dry enough to be removed by an excavator, mixed with soil, and
applied as cover on the refuse landfill. This progression of sludge
filling and subsequent removal enables the trenching operation to be
confined to a small area. The sludge/soil mixture increases the
organic content of the soil and enhances vegetative growth on
completed fill areas at the refuse landfill. The sandy soil at the
site drains well and hence the operation is effective even with the
relatively high rainfall common in the area.
6-6
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FIGURE 6-3
WIDE TRENCH OPERATION WITH DRAGLINE
A privately operated site near Cleveland, Ohio receives 450 wet tons
(408 Mg) of sludge daily from four sources. Most of the sludge is
digested and/or chemically treated, and averages 20% solids. Sludge
is unloaded from haul vehicles directly into trenches. Because of
its consistency, the sludge flows throughout the trench and spreads
out evenly.
The trenches are excavated by a dragline with a 50 ft (15 m) boom and
4.5 yd3 (3.4 m3) bucket. They are 40 ft (12 m) wide, 700 ft (210
m) long, and 5 to 6 ft (1.5 to 1.8 m) deep. Sludge is deposited to a
depth of 3 ft (0.9 m) and is then covered with 5 ft (1.5 m) of soil,
resulting in a mound that ranges from 2 to 3 ft (0.6 to 0.9 m) above
grade. Cover for sludge filled trenches is supplied by spoil
material generated from excavation of the parallel trench. Because
of the low solids content, the cover is applied by the dragline with
the bucket initially at a minimum height. This ensures minimum
displacement of the sludge by cover material. After the first layer
of cover is applied, the dragline applies the remaining cover from a
greater height. The trenches are allowed to settle before a
bulldozer is used to final grade the area. Initial designs called
for a wider trench but experience indicated that the dragline would
have to be moved excessively. Accordingly, the width was reduced to
40 ft (12 m).
6-7
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FIGURE 6-4
WIDE TRENCH OPERATION WITH INTERIOR DIKES
A privately operated sludge landfill in Cleveland, Ohio receives 250
wet tons (226 Mg) of sludge daily from several sources. The sludge
is digested and/or chemically treated and has an average solids
content of 20%. Trenches are 40 ft (12 rn) deep and 700 ft (213 m)
long. Dikes are placed at intervals within the trench to facilitate
phased filling and covering. The dikes are placed at intervals that
ensure frequent cover applications. Sludge is unloaded directly into
trenches and spreads out evenly throughout the contained area. Two
to 3 ft (0.6 to 0.9 m) of cover material is applied by front-end
loaders and excavators excavating a parallel trench. Completed areas
are regraded from 6 to 9 months after cover is applied and subse-
quently reseeded with grass.
6-8
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6.2.2.1 Area Fill Mounds
Area fill mounds may be employed in a variety of topographies. Usually
such operations are conducted on level ground. However, mound landfills
are also well suited to construction against a hillside which can provide
containment on one or more sides.
6.2.2.1.1 Site Preparation
The first step is to prepare the subgrade. Depending on design specifi-
cations this may include underdrains and/or liners for leachate collec-
tion. Due to the large amount of soil required for proper operation of
area fill mounds, emphasis should be placed on securing sufficient soil
material. Accordingly, the fill should be confined to a small area and
proceed vertically to the maximum extent possible. This will reduce the
areal extent of the landfill and consequently reduce erosion and silt-
laden runoff from denuded areas, provided the slope does not become
excessive.
The excavation can be carried out in phases to take advantage of soil
differences. Any soil that has to be stockpiled for use as a sludge
bulking agent should be placed in compacted, sloping piles. To keep the
soil dry, piles may be covered with tarpaulins and the tarpaulins secured
using old rubber tires. Wet soils, because they are not suitable for
sludge bulking, should not be stockpiled. Soil that is stockpiled should
be placed as close as possible to points of eventual use and access to
stockpiles provided.
6.2.2.1.2 Sludge Unloading
The sludge may be unloaded either in the filling area or in the desig-
nated unloading and mixing area near the bulking agent stockpile. The
unloading area should be clean and relatively level for safe passage of
trucks. Haul vehicles should not drive over completed sludge filling
areas.
6.2.2.1.3 Sludge Handling and Covering
Operational procedures should be provided to specify what soils are to be
mixed with sludge, where they are to be obtained, and how they are to be
mixed and/or placed over the sludge. The amount of material required for
each function is determined by site design specifications which take into
account soil and sludge characteristics. Preliminary trial and error
tests to determine sludge/soil ratios that produce sludge with appro-
priate consistencies should be attempted during initial operations.
6-9
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Construction of area fill mounds requires that the sludge/soil mixture be
relatively stable. Sludge/soil mounds are generally applied in a series
of lifts with each lift containing one level of mounds. When completed,
the lift should be covered with a layer of soil sufficient to safely
support on-site operating equipment.
Once the area is filled to the designated contours, the entire fill area
should be covered with 3 to 5 ft (0.9 to 1.5 m) of soil material
(preferably impermeable soil such as clay if it is available). The fill
area should then be final graded to account for future settlement and
promote drainage. A layer of topsoil up to 2 ft (0.6 m) may be used as
final dressing and the area seeded with grass to prevent erosion.
6.2.2.2 Area Fill Layer
Area fill layers may also be employed
Layer operations consist of a series of
final cover applications.
in a variety
sludge layers
of topographies.
with interim and
6.2.2.2.1 Site Preparation
As with area fill mounds, the first step is to prepare the subgrade.
Again, liners and/or subdrain systems may be utilized depending on
hydrogeological conditions. Fill areas for layer operations should be
nearly level. Although the soil requirements of such operations are less
than those of area fill mounds, it may be necessary to import soil. In
any case, soil stockpiles should be established, both for use as bulking
agents and cover soils. Areas should be excavated only as they are used,
to the maximum extent possible. This will reduce the amount of denuded
area subject to erosion.
6.2.2.2.2 Sludge Unloading
Specific unloading and sludge/soil mixing areas may be maintained or
sludge can be placed directly in the fill area. An effective method in
layer operations is to maintain soil stockpiles on the fill area itself.
Bulldozers then mix and layer the sludge in one operation. Again,
storage areas should be located away from traffic.
6-10
-------
6.2.2.2.3 Sludge Handling and Covering
In general, design specifications based on sludge characteristics will
give some indication of the required amounts of bulking agent. Neverthe-
less, it is always advisable to conduct preliminary trial and error tests
to determine bulking ratios appropriate for supporting equipment. The
depth of interim and final cover can also be determined in this manner.
Again, when the area has been filled to the contours established in the
design, a final cover of 2 to 4 ft (0.6 to 1.2 m) should be applied and
the area seeded. It will be necessary to regrade the site in 6 to 12
months, and possibly thereafter as the fill area settles and compacts.
6.2.2.3 Diked Containment
Diked containments are essentially aboveground wide trenches and, as
such, use similar procedures and equipment. The design and construction
of dikes, however, is more complex and is usually not warranted. Only in
cases where high groundwater tables, bedrock and/or low solids, rule out
more conventional methods is their expense justified.
6.2.2.3.1 Site Preparation
The first step in preparing the site for diked containment is to provide
a suitable subgrade or a liner, if necessary. Next, soil should be
imported from other areas if needed. This soil should be relatively
impermeable. The dike base is then constructed maintaining design
dimensions and slopes (generally from 2H:1V to 3H:1V for sideslopes).
Succeeding layers are then applied and each layer compacted by passing
equipment over it. Alternatively, the containment area may be
constructed against one or more steep sideslopes. A ramp should be
provided for unloading vehicles.
6.2.2.3.2 Sludge Unloading
Sludge may be unloaded from the top of the dike or in an area designated
for sludge/soil mixing. Slopes and grades of access roads should be
maintained to design specifications. Provisions should be made for
inclement weather (e.g., stockpiled soil kept dry).
6-11
-------
6.2.2.3.2 Sludge Handling and Covering
The containment area is filled with sludge in layers, usually with
interim soil or gravel cover provided at predetermined heights.
Draglines are frequently used to apply interim and final cover. The
final cover should be 3 to 5 ft (0.9 to 1.5 m) thick. Ideally, this
could consist of a relatively impermeable layer of clay about 1 to 3 ft
(0.3 to 0.9 m) thick, followed by 2 ft (0.6 m) of topsoil [1]. It is
usually necessary to reapply the final cover after initial settlement has
occurred. If additional settlement causes depressions, the site will
have to be regraded. The area should be seeded with a suitable
vegetative cover.
6.2.2.4 Operational Schematics
The preceding information has been included to generally describe the
operation of sludge-only area fills. Figures 6-5 through 6-8 illustrate
specific area fill operations.
6.2.3 Codisposal
In codisposal operations, sludge is received at a landfill receiving
typical municipal refuse. Two kinds of codisposal operations have been
identified including (1) sludge/refuse mixture and (2) sludge/soil
mixture. For sludge/refuse mixtures, sludge is mixed directly with
refuse and landfilled at the working face. For sludge/soil mixtures,
sludge is mixed with soil and used as cover over completed refuse fill
areas. Chapters 3 and 5 should be consulted for specific design
criteria.
6.2.3.1 Sludge/Refuse Mixture
Once sludge receipt has begun, every effort should be made to take full
advantage of the absorptive capacity of the refuse. Consequently, the
sludge should be mixed with the refuse as thoroughly as possible. One
procedure employed calls for refuse to be dumped at the bottom of the
working face, and subsequently pushed, spread, and compacted by equipment
working up the working face. Under these circumstances, sludge can be
handled in two alternative ways. The first way includes:
1. Dump the refuse at the bottom of the working face
2. Dump the sludge atop the refuse pile
3. Thoroughly mix the sludge and refuse
4. Push, spread, and compact the sludge/refuse mixture up the
working face
6-12
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FIGURE 6-5
AREA FILL MOUND OPERATION
A site in Lewiston-Auburn, Maine receives 40 wet tons (36 Mg) per day
of chemically treated sludge. The disposal site is an abandoned
gravel pit with a clay liner and underdrains for leachate collection.
Leachate collected at the site is conveyed to the treatment plant via
a nearby sewer interceptor.
The sludge is unloaded onto a receiving and mixing pad constructed
with gravel and crushed stone. A large covered pile of borrowed sand
is located near this receiving area. Each 10 yd^ (8 ITH) load of
sludge is thoroughly mixed with 6 yd3 (4.6 m3) of fine sand. A
loader then transports the sludge/sand material into the fill area
and pushes and piles the material into 6 to 8 ft (1.8 to 2.4 m) high
mounds. During wet weather, the mounds slump and they must be
continuously piled and pushed by small track dozer. The 8 ft (2.4
m) high mounds form a lift that must be covered by 1 to 2 ft (0.3 to
0.6 m) of gravel to support equipment. Lifts are produced to
complete the site, filling it to its original grade. The entire fill
area will ultimately be covered with an impermeable layer of clay and
graded to ensure proper drainage.
6-13
-------
FIGURE 6-6
AREA FILL LAYER OPERATION
This area fill layer operatjon is
proximately 40 yd3 (30 m3) of
brought to the site daily. The
lime applied to it and is
dewatering. A track loader
sludge ratio) obtained from
10 ft (3 m) wide, 3
layer receives 6 in
located on 150 acres (61 ha). Ap-
digested and dewatered sludge is
25% solids sludge has a thin layer of
then left uncovered to promote further
mixes the sludge with soil (a 3:1 soil to
a stockpile, and applies the material in
ft (0.9 m) thick layers against a slope. Each
(15 cm) of interim cover. A progressive 3:1
slope is constructed from the layering operation,
In wet weather, the track dozer loses traction and is unable to layer
the sludge on the slope. For this reason, a separate wet weather
area is maintained on relatively level ground near the entrance. The
ground beneath the working face is sloped so that
to one end of the area. From here the runoff
holding pond. A final soil cover of 3 ft (0.9 m)
completed slope and the area is seeded. If necessary, sludge is
disced into the soil cover to enrich the soil prior to seeding.
runoff is directed
is directed to a
is applied on the
6-14
-------
FIGURE 6-7
AREA FILL LAYER OPERATION INSIDE TRENCH
A landfill at Frederick, Maryland receives 30 wet tons (27 Mg) per
day of 23% solids sludge. Trenches 45 ft (14 m) wide, 20 ft (6 m)
deep, and 200 ft (60 m) long are constructed with a scraper and track
dozer. A minimum of 20 ft (6 m) of solid ground is maintained bet-
ween trenches. Excavated material is stockpiled along one length of
the trench, but set back at least 20 ft (6 m) from the excavation
edge.
Sludge is unloaded along alternate sides of the trench depending on
weather. When wet conditions prevail, the sludge is unloaded adja-
cent to the stockpile. When the weather is dry and operations of
unloading vehicles and equipment are not hindered,the sludge is
unloaded on the other side. After two loads have been dumped, a
wheel loader mixes soil from the stockpile with the sludge at 1 or 2
parts soil to 1 part sludge. The sludge/soil mixture is then pushed
downslope toward the center of the trench. The operation proceeds
alternatively on each side of the trench. The sludge/soil mixture is
covered daily with a thin Iyer of 2 to 4
2 ft (0.6
(15 to 30
(0.6 m) of
The trench is filled to within
lowed to settle. A 6 to 12 in
applied, followed by about 2 ft
stockpiled separately on-site as the trenches are
design originally called for a narrower 30 ft (9 m)
in. (5 to
m) of the
cm) layer
top soil.
10 cm) of soil.
surface and al-
of clay is then
The top soil is
excavated. The
wide trench, but
experience indicated that the
terms of land use and costs.
wider trench was more efficient in
6-15
-------
FIGURE 6-8
DIKED CONTAINMENT OPERATION
This landfill operation uses a
disposal.
methods but
groundwater
the sludge.
The municipality
decided to use a diked
and bedrock in the area
Containment areas are
material is generated in
diked containment design for sludge
had investigated other landfill ing
containment due to the shallow
and the relatively low solids of
constructed into the side of a
part by excavating the contain-
hill. Soil
ment area with a scraper and a track dozer. This material is mounded
and compacted by the dozer. Additional soil is imported as necessary
from other areas for completing the dikes and for cover soil stock-
piles. When completed, individual diked containment areas are 100 ft
(30 m) long, 40 ft (12 m) wide, and 30 ft (9 m) high. A leachate
control system consisting of a clay liner and leachate collection
pipes is then installed on the floor of the diked containment area.
SOIL STOCKPILE
SOIL STOCKPILE
Each day 200 wet tons (181 Mg) of digested, dewatered sludge is
hauled to the site in large open-top dump trucks. The 20% solids
sludge is dumped directly into the diked containment area. Due to
its liquid nature, individual sludge piles slump considerably and
spread out in the diked containment area. After the sludge reaches a
height of 5 ft (1.5 m), 2 ft (6 m) of interim cover material is
applied atop the sludge by a dragline. Additional interim cover is
applied over the second lift when the sludge reaches a height of 12
ft (3.7 m). A final 5 ft (1.5 m) layer of final cover is applied
over the siudge when it accumulates to within 3 ft (0.9 m) of grade.
6-16
-------
The second method can be accomplished in the following way:
1. Dump the refuse at the bottom of the working face
2. Push, spread, and compact the refuse up the working face
3. Dump the sludge at the top of the working face
4. Push the sludge down the working face, spreading it evenly
across the refuse
If small quantities of sludge are received at refuse landfills (i.e.,
less than 5%) it may be desirable to confine sludge dumping to a selected
location on the working face. This approach is useful in landfills that
are sufficiently large to ensure that refuse dumping proceeds
simultaneously along a wide working face.
Precautions should be taken to contain any sludge which escapes from the
working face. This may be particularly needed for a sludge with a low
solids content. Containment can be achieved either by (1) landfill ing
the sludge in a small depression or (2) constructing a refuse or soil
berm at the bottom of the working face.
Other factors to be considered for refuse landfills receiving sludge
include increased odors and the possibility of a small increase in
leachate generation. Appropriate steps can be taken to control odors
including more frequent application of cover and spot addition of lime.
6.2.3.2 Sludge/Soil Mixture
Another option for handling sludge at refuse landfills is mixing the
sludge with soil and then applying the mixture as cover material over
refuse-filled areas. Although this technically is not sludge
landfill ing, it is a viable alternative, is particularly useful in
promoting vegetative growth in completed fill areas, and is performed at
numerous refuse landfills.
The application of this sludge/soil operation may proceed follows:
1. Spread sludge as received uniformly over the ground surface in a
3 to 6 in. (8 to 15 cm) thickness in an area designated for this
purpose.
2. Disc the sludge into the soil.
6-17
-------
3. Spread lime or masking agent over the sludge/soil mixture for
odor control if necessary.
4. After a period ranging from 1 to 8 weeks time (depending on
rainfall and climate) scrape up the sludge/soil mixture and
spread it over completed fill areas where vegetative growth has
been slow to take root.
6.2.3.3 Operational Schematics
The preceding information has been included to generally describe the
operation of codisposal sites. Figures 6-9 through 6-11 illustrate
specific codisposal operations.
6.3 General Operational Procedures
Operational factors that are generally applicable to all sludge
landfill ing methods include:
1. Environmental control practices
2. Inclement weather practices
3. Hours of operation
4. Special wastes
6.3.1 Environmental Control Practices
In many cases, environmental controls must be designed and constructed to
lessen the environmental effects of sludge landfills. Maintaining these
controls is necessary to the landfill operation. Common sense control
practices will also help ensure an environmentally sound disposal opera-
tion. These environmental control practices are described in the follow-
ing sections and outlined in Table 6-1.
6.3.1.1 Spillage
Enroute and on-site spillage of sludge must be cleaned up as soon as pos-
sible. Haul vehicles enroute to the disposal site should report even
small spills to the operation supervisor, so emergency clean-up crews can
take prompt action. On-site spills should be controlled as much as pos-
sible. It is a good policy to have lime on hand at all sludge disposal
operations for spot application to spills if prompt clean-up is not
6-18
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FIGURE 6-9
SLUDGE/REFUSE MIXTURE OPERATION
A site near Pittsburgh, Pennsylvania receives 100 wet tons (91 Mg)
per day of 22% solids sludge. Two or three confined areas at the
operating face are designated for sludge disposal. A layer of refuse
is spread on the ground at the toe of the working face and the driver
of the sludge haul vehicle directed to unload the sludge on top of
the refuse so that the sludge is absorbed by the refuse. Generally,
a few hours are allowed to permit the sludge to be absorbed by the
refuse. More refuse is then piled on the sludge and a bulldozer
mixes the sludge with the refuse at a ratio of approximately four
parts refuse to one part sludge. Any ratio less than this has been
found to cause soft spots in the fill area and create operational
problems. The mixture is then pushed up the working face with
bulldozers and compacted. An interim soil cover is applied at the
end of each working day.
The timing of sludge deliveries is critical since there must be
sufficient refuse available for operations to proceed. Accordingly,
sludge deliveries are timed to coincide with refuse deliveries, which
occur in the morning and early afternoon. The site encounters prob-
lems in wet weather. The 4:1 refuse mixture is found to be inade-
quate when the refuse is wet. The usual solution has been to in-
crease refuse quantities. During warm weather the site experiences
some odor problems. Masking agents are used when odors are a prob-
lem.
6-19
-------
FIGURE 6-10
SLUDGE/REFUSE MIXTURE WITH DIKES
A codisposal site at Stafford, New Jersey, receives about TOO wet
tons (91 Mg) of 17% solids sludge per day at specified locations on
the working face. The sludge is deposited at the top of the
and allowed to flow down the face into a refuse berm
structed at the toe of the face. The ratio of refuse
generally about 4 to 5 parts refuse to one part sludge.
of the day, the refuse is mixed with the sludge and pushed up the
working face. Subsequently the mixture is compacted and cover
applied. At times the operation has had difficulty containing the
sludge during mixing operations, but by maintaining suitable ratios,
the problem has been alleviated.
slope
that is con-
to sludge is
At the end
This technique enables operators to store refuse, which arrives at
the site in the morning and early afternoon, and coordinate mixing
operations with the sludge, which arrives continuously during the
working day. Vegetation has been slow to take root in completed fill
areas because the soil is sandy and has a low organic content. As a
result plans are now underway to disc sludge into the soil
applying final cover.
prior to
The site is on a coastal plain and consequently has a milder climate
than areas in similar latitudes. As a result, the site has not had
problems with winter operations. However, during heavy rains the
refuse dikes can become water logged, thus reducing the absorptive
capacity of refuse.
6-20
-------
FIGURE 6-11
SLUDGE/SOIL MIXTURE
A codisposal site near Washington, D.C. uses a sludge/soil mixture as
final cover for completed fill areas. The site receives digested,
dewatered sludge averaging 22% solids from 4 treatment plants.
Sludge makes up about 10% of the total waste received at the site.
The sludge is dumped in designated areas, spread evenly over the area
in a thin layer, and thoroughly mixed with the soil using a discing
apparatus. Approximately one week later, the sludge-soil mixture is
scraped up and a masking agent added. It is then applied over com-
pleted areas as a soil enrichener. The mixture is generally 1 part
sludge to 1 part soil. It was found that the mixture worked well in
enhancing vegetative growth.
The site encounters some problems, with the operation particularly
during winter operations when the soil is frozen and discing is
difficult. At these times an alternative procedure, sludge/refuse
codisposal, is generally used. Other problems that the site has
encountered are mild odor problems. This is handled by applying
masking agents.
A stream bisects the site and consequently runoff is carefully con-
trolled. The stream is culverted and runoff is directed to siltation
ponds so that discharge to the stream can be controlled.
6-21
-------
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TABLE 6-1
ENVIRONMENTAL CONTROL PRACTICE
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6-22
-------
feasible. The use of haul vehicles with baffles on them has been used
effectively to limit spills.
6.3.1.2 Siltation and Erosion
The presence of silt-laden runoff from the site is often the result of
improper grading. Grades of 2 to 5% should be maintained where feasible
to promote overland surface drainage, while minimizing flow velocities.
Denuded areas should be kept to a minimum during site operation. On-
going construction and maintenance of sediment control devices (e.g.,
grass waterways, diversion ditches, rip-rap, sediment basins) are criti-
cal for an environmentally sound operation. During site completion,
proper final grading, dressing, and seeding prevent long-term erosion and
siltation problems.
6.3.1.3 Mud
Mud is usually caused by improper drainage but can be a problem at any
site during heavy rains or spring thaws. To minimize the effect of mud
on operations, access roads should be constructed of gravel. If practi-
cal, a wash pad should be located near the exit gate to clean mud from
transport vehicles.
6.3.1.4 Dust
Dust is usually caused by wind or the movements of haul vehicles and
equipment. To minimize dust, access roads should be graveled. Also,
areas that are covered with interim or final soil cover should be
vegetated as soon after their completion as possible. As an alternative,
water can be applied to dusty roads.
6.3.1.5 Vectors
Vectors at sludge landfills include flies and mosquitos. Flies can be
best controlled by placing adequate compacted cover soil as frequently as
possible. Studies have shown that a daily cover consisting of 6 in. (1.3
cm) of compacted low-clay content soil will prevent fly emergence. How-
ever, even under the best of conditions, a sludge landfill should have a
regular inspection and fly control program. Local controls can best
dictate the specifics of any such program. Mosquito control is best
6-23
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obtained by preventing development of stagnant water bodies anywhere on
the site. Continuous grading to fill low spots is essential.
6.3.1.6 Odors
Odors can be a serious problem at a sludge landfill unless preventive
steps are taken. The sludge should be covered as frequently as necessary
to minimize odor problems. Lime or chemical masking agents can be ap-
plied to reduce odor problems. An effective means of reducing odors is
to limit storage of the sludge. Ideally, storage of sludge should be
accomplished at the wastewater treatment plant.
6.3.1.7 Noise
Noise sources at sludge landfills include operating equipment and haul
vehicles. Generally, the noise is similar to that generated by any heavy
construction activity, and is confined to the site and the streets used
to bring sludge to the site. To minimize the effect, every effort should
be made to route traffic through the least populated areas. Further, the
site can be isolated so that the noise cannot carry to nearby neighbor-
hoods. The use of earthen berms and trees as noise barriers can be very
effective. On the site, noise protection for employees will be governed
by existing Occupational Safety and Health Act (OSHA) standards.
6.3.1.8 Aesthetics
To make the sludge landfill acceptable, every attempt should be made to
keep the site compatible with its surroundings. During site preparation,
it is important to leave as many trees as possible to form a visual
barrier. Earthen berms can be similarly used. The use of architectural
effects at the receiving area, the planting of trees along the property
line, and confining dumping to designated areas will assist in the devel-
opment of a sound operation. Additionally, every attempt should be made
to minimize the size of the working area.
6.3.1.9 Health
Although there is a possibility that pathogens will be present in sludge,
particularly if undigested, no health problems have been reported by site
operators. Nevertheless, personnel should use caution when transporting,
handling, and covering sludge. Washing facilities should be located on
or near the disposal site for use in case of bodily contact with sludge.
6-24
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6.3.1.10 Safety
As with any construction activity, safety methods must be implemented in
accordance with OSHA guidelines. Work areas and access roads must be
well marked to avoid on-site vehicle mishaps.
6.3.2 Inclement Weather Practices
Prolonged periods of rainy weather or freezing temperatures can impede
routine operation of a sludge landfill. Anticipating the operational
problems and addressing contingency operations in the operation plan will
promote efficient operations. A listing of potential inclement weather
problems and solutions has been included in Table 6-2.
6.3.3 Hours of Operation
Hours of operation should coincide with hours of sludge receipt. In this
way, personnel and equipment are available to direct trucks to the proper
unloading location; assist if trucks become mired in sludge or mud;
and/or cover the sludge quickly to minimize odors. If the operation plan
calls for daily covering of sludge, hours of operation should continue at
least 1/2 hr past the hours of sludge receipt to allow for cleanup
activities. Sludge deliveries after hours at the landfill should be
discouraged.
6.3.4 Special Wastes
Municipal sludge landfills will generally receive grit, skimmings,
screenings, and ash periodically. In most cases, handling and
landfill ing procedures are similar to those employed for sludge, but
there are some important exceptions. Grit, screenings, and skimmings,
because of their high organic content, are frequently sources of odor.
Consequently, landfills may charge a higher fee and will usually not
stockpile these wastes. Delivery of grit, screenings, and skimmings
should be coordinated with active operating hours to assure that they can
be processed. Ash, on the other hand, can be stored but should be kept
dry if possible. If ash composition a significant portion of the waste
disposed, then application rates should be lowered because of the
relatively higher heavy metal concentrations. A further discussion of
the characteristics and comparison of ash is presented in Chapter 3,
Sludge Characteristics and Landfill ing Methods.
6-25
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TABLE 6-2
INCLEMENT WEATHER PROBLEMS AND SOLUTIONS
Inclement
Weather Sludge Loading
Conditions and Transport
Wet Problem: If hauling
great distances, wet
weather conditions
may increase liquid
content of sludge.
Solution: Cover
transport vehicle.
Cold Problem: Sludge
freezes in haul
vehicles.
Solution: Line
trucks with salt
water, straw, sand
or oil . Do not
allow prolonged
exposure to cold
(park in garage).
Use exhaust to
heat the trailer.
Site Preparation
Problem: Maneuvera-
bility of equipment
hindered in mud.
Solution: Plan to move
operation to an acces-
sible working area.
Problem: Depressions
accumulate water, may
draw flies, mosquitos.
Solution: Grade area
to promote surface
runoff. Use insecti-
cides only when neces-
sary.
Problem: Deep pene-
tration of frost in
trench areas.
Solution:
- Construct trenches
during good weather
and save for cold
months.
- Do not remove snow
(acts as insulator)
or allow vehicles
to ride on trench-
ing areas (causes
frost to penetrate
deeper into the
ground) .
- Hydraulic rippers
or jackhammers are
to be used as a last
resort.
Sludge Unloading
Problem: Maneuvera-
bility of transport
vehicles hindered in
mud.
Solution: Place sand
or gravel in areas to
improve traction. In-
crease depth of road
material.
Problem: Instability
of trench walls may
cause collapse while
unloading.
Solution: Have trans-
port vehicle dump at
trench 1 ip and push
sludge into trench
with equipment.
Problem: Mud and sludge
accumulates on haul
vehicles and equipment.
Solution: A washing pad
at the receiving area
will clean vehicles.
Problem: Tailgates
freeze.
Solution: (1) Spray
ethylene glycol on
frozen parts. (2) use
exhaust to heat frozen
parts.
Problem: Previously
(f al 1 season) muddy
roads form severe ruts
and chuck holes.
Solution: Regrade and
build before winter
reeze.
Sludge Handling
and Covering
Problem: When
mixing sludge
with refuse or
soil , need more
mixing material .
Solution: Ensure
sufficient supply
of refuse or soil
material .
Problem: Ponded
water collecting
in trenches.
Solution: Use
potable pump
to remove
excess water.
Problem: Deep
penetration of
frost in cover
supply areas.
Solution: Accum-
ulate stockpile
in good weather.
Ensure supply of
cover material ;
insulate piles
with tarpaulin or
hay.
Problem: Equlp-
ment freeze-up.
Solution: Trucks
or crawlers should
be well cleaned
of sludge and
soil.
6-26
-------
Another factor that should be anticipated is the fluctuations in treat-
ment plant operations and the consequent variation in the characteristics
of the sludge delivered. Occasionally, excessively wet or malodorous
loads may be received. Operational procedures should be established for
these loads. Typically, procedures range from outright refusal of the
load to maintenance of special areas or soil stockpiles to handle
substandard loads.
6.4 Equipment and Personnel
A wide variety of equipment is utilized at sludge landfills. Equipment
selected depends largely on (1) landfill ing method and design dimensions
employed and (2) quantity of sludge received.
Since equipment represents a large capital investment and accounts for a
large portion of the operating cost, equipment selection should be based
on a careful evaluation of the functions to be performed and the cost and
ability of various machines to meet these needs. Contingency equipment
for downtime and maintenance may be necessary at larger sites. These may
be rented or borrowed from other municipal functions.
Table 6-3 provides guidance on the suitability of equipment to perform
selected sludge landfill ing tasks. Table 6-4 provides typical equipment
selections for seven operational schemes. These matrices are meant to
give general guidance on the selection of sludge landfill equipment.
However, it should be noted that general recommendations on equipment
selection can be misleading. In all cases, final selection should be
based on site-specific considerations. Figures 6-12 through 6-15
illustrate typical equipment used at sludge landfills.
The importance of employing qualified
sludge landfills cannot be overstated.
the difference between a well-organized,
operation.
and well-trained personnel at
Qualified personnel often make
efficient operation and a poor
Typical positions required at sludge landfills include the following:
1. Equipment Operator. At many sludge landfills, these will be the
only personnelrequired. Tasks performed are mostly those of
equipment operation. However, other tasks include routine
equipment maintenance and directing sludge unloading
operations.
6-27
-------
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6-29
-------
FIGURE 6-12
SCRAPER
FIGURE 6-13
BACKHOE WITH LOADER
•"**•», "
•.'•:\. #,?-
6-30
-------
FIGURE 6-14
LOAD LUGGER
FIGURE 6-15
TRENCHING MACHINE
6-31
-------
2. Superintendent/Foreman/Supervisor. This position involves
overseeingallaspectsofthe landfill operation, including
keeping cost records, processing personnel grievances, and
managing the operation. Also, this person often serves other
functions, such as operating equipment.
3. Mechanic. Major equipment maintenance and repair is performed
by qualified mechanics. Mechanics or maintenance teams seldom
are needed full-time on site. They may come to the site as
repairs are required.
4. Laborer. Larger sites may need one person to maintain control
devices for leachate collection and treatment, odor control, and
mud and dust control. He also can ensure that fencing and
access roads are properly maintained.
6.5 Reference
1. Leadbetter, R. H. Design Considerations for Pulp and Paper-Mil 1
Sludge Landfills. U.S. Environmental Protection Agency. EPA 600/
3-786-111, December 1976.
6-32
-------
CHAPTER 7
MONITORING
7.1 Introduction
Environmental and legal sensitivity to potential water contamination
necessitates the monitoring of sludge landfills. The purpose of
monitoring may include establishing baseline data, detecting contamina-
tion, satisfying regulatory constraints, securing data for use in litiga-
tion, or conducting research projects. Despite the particular objective
of any monitoring network, site monitoring will continue to constitute an
increasingly integral component of any sludge landfill operation. Ideal-
ly, monitoring should be used to confirm the predictions and judgements
made during the project development and design stage with respect to
protecting the ecosystem. Monitoring at a sludge landfill usually
addresses groundwater and/or surface water and occasionally gas migra-
tion. Monitoring of surface water and gases are not required if there
are no surface water bodies or structures nearby.
7.2 Groundwater Monitoring
A series of evaluations are usually made prior to implementation of
groundwater monitoring. The items to be evaluated include:
1. Pertinent conditions of the hydrologic framework
2. Characteristics of the sludge received
3. Man-induced and geologic features affecting the movement of
leachate.
4. Groundwater use
7.2.1 Hydrologic Conditions
In a preliminary form, the following items require determination for
hydrologic characterization at a site:
1. Climatological setting
2. Groundwater delineation such as depth, flow patterns, fluctu-
ations, etc.
7-1
-------
FIGURE 7-1
LANDFILL WATER BALANCE SIMPLIFIED
(PREC
+ IRR
"s
PIT*
GAT
\/
moN
ON)
/ (EVAPQTRA
\
ASPIRATION)
(SWFflCE RUNOfT)
GROUND-WATER FUDW
Figure 7-1 is a simplified hydrologic cycle illustrating these factors.
Examination of these hydrologic components should be conducted to a level
of detail commensurate with the goals of the proposed monitoring system.
7.2.1.1 Climate
Information of interest includes:
1. Historical rainfall intensity data for a 24-hr period
2. Maximum monthly and yearly precipitation data
3. Temperature, evapo-transpiration, and wind information
These records can usually be obtained from a nearby National Oceanic and
Atmospheric Administration (NOAA) weather station. Estimates of such
data may be necessary if sources for existing data are unavailable.
7-2
-------
7.2.1.2 Groundwater Conditions
An examination of the groundwater system includes the following:
1. Groundwater streamline patterns
2. Depth of groundwater
3. Groundwater quality and uses
4. Seasonal fluctuations in depth
Prior to any field investigation a number of information sources should
be contacted to define the regional and local hydrologic regime. Re-
gional sources include federal, state, and private publications, maps,
aerial photographs, and remote sensing imagery. Useful local information
can be obtained from consultants, well drillers, city or county agencies,
nearby universities, and adjacent land owners. These other sources
usually provide data for both regional and site specific conditions.
If existing background data does not provide sufficient information on
groundwater conditions, a relatively inexpensive method utilizing three
wells can be used to supplement this knowledge. The usual process in-
volves installing three well points below the groundwater table in a
triangular arrangement surrounding sludge landfills. Absolute elevations
of each well are surveyed and recorded. Water level measurements in
these wells are made periodically, and water level contours developed.
This provides information on streamline (flow) patterns, groundwater
depths, and, if monitored throughout the course of a year, data on sea-
sonal groundwater fluctuations. Background groundwater quality levels
should also be identified, either by reviewing available information or
by analyzing water samples from nearby wells upstream from the sludge
landfill.
7.2.2 Sludge Characteristics
Ideally, the sludge should be thoroughly characterized prior to landfil-
ling. The viability of its chemical and physical properties should also
be determined. Characteristics of primary interest are the solids con-
tent, heavy metals (e.g., lead, zinc, cadmium), pH, and nitrates. In
addition, organics and cyanides are important constituents that should be
identified. Constituents that are present at relatively high concentra-
tions and/or are highly soluble in water should be included in the
groundwater analysis since it is likely that these constituents would be
present in the leachate.
7-3
-------
7.2.3 Man-Induced and Geologic Features
Other factors which can influence the groundwater flow patterns or con-
tamination levels are wells, subsurface barriers, geologic conditions, or
nearby possible waste point sources. These factors could manifest them-
selves in a variety of features such as fractured bedrock, abandoned
wells, highly porous soil horizons, septic tanks, etc. Depending upon
the intensity of the monitoring, either a background geologic report (if
available) or an on-site investigation is needed. Field geologic examina-
tions should include all geologic formations down to and including the
aquifer.
7.2.4 Field Installations
Proper location and installation of monitoring wells are essential to a
monitoring program. A number of excellent references should be reviewed
for determining which combinations best suit a particular monitoring
program [1][2][3][4][5][6][7]. Generally, once the hydrogeological
setting and the waste characteristics have been defined, it is possible
to develop a site specific monitoring plan [1][8][9].
In field installations, particular attention should be given to two major
items to ensure optimum benefit from each sampling point. These items
are proper vertical and horizontal placement and the selection of samp-
ling devices best suited to the particular goals of the study. The loca-
tions and depths at which the monitoring wells or devices are placed
should be based on the information obtained during the site investiga-
tion. Monitoring wells should be placed in those areas representing
optimum pathways for contaminants migrating from the sludge landfill.
Wells should be installed 10 ft (3 m) or deeper into the groundwater.
Knowing (1) the age of the sludge landfill, (2) approximate permeability
values in the zone of aeration, and (3) directions and velocities of
groundwater flow, rough estimates can be derived as to the maximum aerial
extent of contaminant migration. This approximation can provide a zone
of highest probability for leachate detection.
7.2.4.1 Characteristics of the Aquifer
Some of the site-specific characteristics that will influence the place-
ment of monitoring wells are:
1. Geologic nature of the aquifer
2. Characteristics of the potential leachate
3. Groundwater flow rates
7-4
-------
For the purposes of monitoring, it is useful to categorize an aquifer
according to the nature of its porosity. Porosity, in lurn, may be
intergranular, fracture induced, or solutional. Unconsolidated alluvium
and consolidated sedimentary rock usually exhibit flow via intergranular
porosities; crystalline rocks exhibit movement via fractures, and
limestone, marble, and other soluble rocks exhibit movement via
solutional channels.
The rate of groundwater flow through some sedimentary or alluvial aqui-
fers may be much slower (typically 4.9 ft/yr (1.5 m/yr)) in clay or
compacted shales than in solutional or fractured aquifers (up to 16
ft/day (5 m/day)). The distance at which monitoring stations should be
located is determined in part by the rate of groundwater flow: a greater
down-gradient distance is required for rapid flows, a shorter distance
for slower rates.
The movement of groundwater through sedimentary aquifers is generally
isotropic, determined chiefly by the gradient. Flow through fractured or
solutional rock, on the other hand, exhibits preferential channels of
movement. Again, the placement of monitoring wells should accommodate
these differences by locating monitoring wells along major fractures or
solution channels where appropriate.
The depth to which a well should penetrate the aquifer is partly a func-
tion of the leachate. Since groundwater exhibits laminar flow in most
aquifers, it does not generally disperse itself through the aquifer,
rather it moves in a cohesive plume. This plume may "float" atop the
water table or "sink" to the bottom, depending on the specific gravity of
the leachate. Knowing the nature of the potential contaminants will
enable landfill operators to predict the movement of the plume and
consequently the extent of penetration required for monitoring wells.
Other characteristics of the aquifer that should be ascertained are the
presence of artesian pressure, presence of multiple aquifers separated by
aquitards or aquicludes, and the location and orientation of faults and
major fractures through the aquifer. Perched water tables should also be
located and their relationship to the primary aquifer ascertained.
7.2.4.2 Sampling and Monitoring Program
lired at the sludge disposal site is highly site-
i i ^t Qhnnlri hp rnnQiiltpH to accict in Hotormininn
The number of wells required at the sludge dispo:
specific. A hydrogeologist should be consulted •
the number of wells required and their locations.
to assist in determining
7-5
-------
Generally the following types of wells are needed:
t Background wells - located upstream, not affected or contaminated
by landfill leachate
• Downstream wells - Located a few hundred feet downstream from the
landfill, used to detect leachate migration; others located
immediately downstream of the fill area in the zone of maximum
leachate concentration
Care must be taken to ensure that exterior sources or seasonal fluctu-
ations of the streamlines do not interfere with any of these wells.
Often these monitoring wells or at least several of the wells will have
been installed during the site selection and/or design investigations.
In fact, it is desirable to start monitoring the wells 6 months to a year
before any sludge filling to establish background groundwater quality
including any seasonal fluctuations, to determine positively whether the
landfill is affecting the water quality.
An actual monitoring network, established to monitor an existing land-
fill, is presented in Figure 7-2. A hydrogeologist was consulted and
assisted in locating the wells. After a visual inspection of the site,
the hydrogeologist recommended that resistivity surveys be conducted.
FIGURE 7-2
WATER TABLE AND LAND SURFACE CONTOUR MAP
WITH TEST WELL LOCATIONS
LEGEND
• 3 TEST WELL
— 8— WATER LEVEL CONTOUR
50-- GROUND CONTOUR
-------
Based on the results of this and on analysis of surface water from the
marsh, the extent of potential pollution was predicted and locations for
monitoring wells determined. Table 7-1 presents the wells that were
constructed.
TABLE 7-1
WELL CONSTRUCTION DETAILS, WATER LEVELS AND
WATER QUALITY (PHYSICAL)
(all wells equipped with 2-ft screen or well point)
Well
1
2
3
4
5
1 in
1 ft
rc
Well
diameter
(in.)
2.5
1.5
2.5
1.5
2.5
. = 2.54 cm
= 0.305 m
= 5/9 (F-32)
Well
depth
(ft)
60
60
50
45
40
Depth to
water
(ft)
46
44
33
36
27
Specific
conductance
(uMOHS/cm)
210
220
210
270
240
Temperature
(°F)
65
65
65
65
67
Accountability and documentation should be emphasized in any monitoring
program. Logs should be kept that indicate the date, time, method, and
other pertinent conditions existing at the time of sampling. Wells
should be kept locked and samples should be handled as indicated in
"Procedures Manual for Monitoring Solid Waste Disposal Sites" [7]. In
addition, where litigation is anticipated, it is valuable to use an
independent lab for sample analysis.
7.2.5 Sample Collection
7.2.5.1 Materials and Equipment
The type of sampling device chosen for groundwater monitoring will depend
upon the sludge landfill's physical setting and funding. Figure 7-3 is
an example of a typical monitoring well. Important features include an
impermeable backfill, PVC piping and well screen, and gravel fill around
the well screen. Figure 7-4 illustrates the install ion of well points to
collect samples from several depths.
7-7
-------
FIGURE 7-3
TYPICAL MONITORING WELL SCREENED
OVER A SINGLE VERTICAL INTERVAL
LAND SURFACE
SLOPED AWAY
FROM WELL
BOREHOLE
SCHEDULE 40 PVC
CASING
SLOTTED SCHEDULE
40 PVC SCREEN
LOW PERMEABILITY
BACKFILL
GRAVEL PACK
WATER TABLE
7-8
-------
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7-9
-------
The composition of the materials selected for groundwater monitoring
should be examined for possible contamination and interference with the
chemical analysis. For example, galvanized pipe should not be used when
testing for trace metals. Inert materials such as ABS or PVC reduce the
possibility of erroneous readings, although the glues used on the
fittings can contaminate samplings. Disinfection of wells, equipment,
and containers by chlorination or other means is required if
bacteriological examination is included. Several excellent documents
outlining containers and preservation techniques for individual species
are available [1][10][11][12].
7.2.5.2 Collection Techniques
Well sample collection techniques deserve careful analyses. Whether the
bail, air lift, or vacuum method is used, the interaction of these proce-
dures with the prescribed analyses requires consideration [13][14]. The
means of obtaining the sample depends upon the analyses to be performed.
For example, sampling of groundwater for reduced species (e.g., H£ and
redox measurements) should exclude the possibility of air contamination
or °? injection into the sample. Systems utilizing pumping or air
injection would interfere with true j_n situ measurements. Collection
techniques should remain consistent throughout the duration of the
monitoring. Pumping a well for a certain period of time prior to
obtaining a sample is recommended. At a minimum, the volume of the
standing water should be removed. If time and the recovery of the
aquifer permit, 2 to 3 volumes should be removed prior to sampling.
Similarily, collection equipment (air lift versus bail) should remain the
same. In this way, the results of the program will not be compromised
due to collection variations.
7.2.5.3 Sampling Frequency
The frequency of sample collection is dependent upon the goals of a par-
ticular program (i.e., whether it is long or short term) and on the
specific characteristics of the site (i.e., soils, climate). The esti-
mated rate of travel of pollutants in a given hydrogeological setting
will suggest intervals of time which will show a change in water quality.
Analyses of the initial and second samplings may suggest an adjustment of
the sampling frequency. Studies indicate that leachates frequently are
released in slugs, or high concentrations, at periodic intervals that are
seasonally or climatically influenced [6]. This may dictate intensified
sampling efforts at certain times. Regulatory agencies often require
quarterly sampling. Sampling frequency should reflect the requirements
of the appropriate regulatory agencies as a minimum. However, the
required sampling frequency is site specific and hence should be adjusted
if experience indicates that more frequent samplings are necessary.
7-10
-------
7.2.6 Analytical Parameters
The parameters or constituents included in the analysis of groundwater
samples depend on such factors as monitoring goals and levels, funding,
waste composition, uses of groundwater, regulatory requirements, etc. If
the groundwater is potable, parameters for which drinking water standards
have been established should be measured [15]. If high concentrations of
certain heavy metals, or toxic chemicals, are detected in the sludge,
they should be included on the groundwater monitoring list. No list of
parameters applies to all cases. However, a recent study indicates that
lead, iron and TOC are the constituents most frequently observed in
leachate from sludge landfills and consequently may be considered as good
indicator parameters. Based on sludge characteristics and a recent study
[6], it is recommended that the following parameters be analyzed
regardless of uses:
1. pH
2. Electrical conductivity or total dissolved solids (TDS)
3. Iron
4. Nitrate
5. Chlorides
6. Total organic carbon (TOC) (if not feasible, COD)
7. Heavy metals (expecially lead)
8. Methylene blue-active substances (optional, depending on
sludge).
The water temperature and depth at the time of sampling should be noted.
The results from the downstream and on-site wells should be compared with
those from the background well and the drinking water standards or other
pertinent regulations [15]. Seasonal variations in contaminant concen-
trations should be noted. Typical quantities of dissolved solids are
presented in Table 7-2.
7-11
-------
TABLE 7-2
RELATIVE ABUNDANCE OF DISSOLVED SOLIDS IN POTABLE WATER [16]
Major Constituents (1.0 to 1,000 mg/1)
Sodium Bicarbonate
Calcium Sulfate
Magnesium Chloride
Silica
Secondary Constituents (0.01 to 10.0 mg/1)
Iron Carbonate
Strontium Nitrate
Potassium Fluoride
Boron
Minor Constituents (0.001 to 0.1 mg/1)
Antimony Lead
Aluminum Lithium
Arsenic Manganese
Barium Molybdenum
Bromide Nickel
Cadmium Phosphate
Chromium Rubidium
Cobalt Selenium
Copper Titanium
Germanium Uranium
Iodide Vanadium
Zinc
Trace Constituents (generally less than 0.001 mg/1)
Beryllium Silver
Bismuth Thallium
Cesium Thorium
Gallium Tin
Gold Tungsten
Indium Zirconium
Lanthanum Platinum
7-12
-------
7.2.7 Analytical Methods
7.2.7.1 Sample Size and Preservation
Table 7-3 is a brief description of sampling methods recommended by Chi an
and DeWalle for the sampling of concentrated leachate, as presented in
"Procedures Manual for Groundwater Monitoring of Solid Waste Disposal
Facilities" [1]. Information and methods of minimizing interferences are
included in this table as well as recommendations concerning sampling
containers and volumes required. This document also provides an
excellent discussion of analytical methods for leachate analysis.
7.2.7.2 Field Testing Versus Testing in the Laboratory
The majority of tests performed on leachate samples are run in the ana-
lytical laboratory on samples which have been preserved by refrigeration
or chemical means. A limited number of tests, however, can be performed
at the sampling site on a freshly drawn sample. There are a number of
advantages in field testing in which sample degradation is practically
eliminated, along with the need for sample preservation, transportation,
and handling. An added advantage is the ability to re-sample and re-
analyze immediately, on site, if it is suspected that a particular sample
is not representative or valid. There are also disadvantages encountered
in field testing and these usually relate to the reliability of the
particular method and equipment used for the test.
Some tests can be run in the field with the same methods and equipment
which would be used in the laboratory and yield the same reliability.
Among such tests are those involving the measurements of pH, oxidation,
and specific ions by means of specific ion electrodes. The equipment
used in these tests is available in portable models which are of equal
applicability in the field and laboratory.
Other tests are sometimes performed exclusively in the field using
methods and equipment specifically designed for field use. A number of
commercial kits are available for such purposes. While offering distinct
advantages, there are also disadvantages inherent in the use of field
kits. An evaluation of field kit usage is presented in "Handbook for
Monitoring Industrial Wastewater" [17].
7.3 Surface Water Monitoring
Surface water monitoring is usually implemented as a routine component of
a total network. The proximity of a sludge landfill to surface water and
drainage patterns will determine whether surface water monitoring is
necessary.
7-13
-------
TABLE 7-3
SAMPLE SIZE AND
SAMPLE PRESERVATION9
Measurement
Acidity
Alkalinity
Arsenic
BOD
Branide
COD
Chloride
Chlorine Req.
Color
Cyanides
Dissolved
Oxygen
Probe
Winkler
Fluoride
Hardness
Iodine
NBAS
Metals
Dissolved
Suspended
Total
Mercury
Dissolved
Total
Nitrogen
Ammonia
Kjeldahl
Nitrate
Nitrite
NTA
Oil S Grease
Organic Carbon
pH
Phenol ics
Vol.
reg.
(ml)
100
100
100
1,000
100
50
50
50
50
500
300
300
300
100
100
250
200
100
100
100
400
500
100
50
50
1,000
25
25
500
Container
P,Gb
P,G
P,G
P,G
P,G
P,G
P.G.
P,G
P.G
P,G
G only
G only
P.G
P,G
P.G
P,G
P,G
P.G
P,G
P,G
P,G
P.G
P.G
P,G
G only
P,G
P,G
G only
Preservation
Cool , 4°C
Cool, 4°C
HN03 to pH < 2
Cool , 4°C
Cool , 4°C
H2S04 to pH < 2
None Req.
Cool , 4°C
Cool, 4°C
Cool , 4°C
NaOH to pH 12
Det. on site
Fix. on site
Cool, 4°C
Cool , 4°C
Cool , 4°C
Cool , 4°C
Filter on site
HNO, to pH < 2
Filter on site
HN03 to pH < 2
Filter
HN03 to pH < 2
HN03 to pH < 2
Cool , 4°C
HoSOa to pH < 2
Cool , 4°C
HjSOd to pH < 2
Cool , 4°C
H2S04 to pH < 2
Cool , 4°C
Cool , 4°C
Cool , 4°C
H2S04 to pH < 2
Cool , 4°C
H2S04 to pH < 2
Cool , 4°C
Det. on site
Cool , 4°C
H3P04 to pH < 4
1.0 g CuS04/l-
Standard
Holding Method
timef NumberS
24 hrs
24 hrs
6 raos
6 hrsc
24 hrs
7 days
7 days
24 hrs
24 hrs
24 hrs
None
None
7 days
7 days
24 hrs
24 hrs
6 months
6 months
38 days
(glass)
13 days
(hard
plastic)
38 days
(glass)
13 days
(hard
plastic)
24 hrsd
24 hrsd
24 hrsd
24 hrsd
24 hrs
24 hrs
24 hrs
6 hrsc
24 hrs
402
403
404
507
406
508
408
412
204
413
402
414
309
416
512
301
315
417
418
421
419
420
—
502
505
424
574
7-U
-------
TABLE 7-3
(continued)
Measurement
Phosphorus
Ortho-
phosphate,
dissolved
Hydrolyzable
Total
Total .
dissolved
Residue
Filterable
Non-filterable
Total
Volatile
Settleable
matter 1
Selenium
Silica
Specific
conductance
Sulfate
Sulfide
Sulfite
Temperature 1
Threshold
odor
Tu rb i d i ty
Vol.
rey.
(ml)
50
50
50
50
100
100
100
100
,000
50
50
100
50
50
50
,000
200
100
Container
P.G
P,G
P.G
P.G
P.G
P,G
P.G
P.G
P,G
P.G
P only
P.G
P.G
P.G
P.G
P.G
G only
P.G
Preservation
Filter on site
Cool, 4°C
Cool , 4°C
H2S04 to pH < 2
Cool, 4°C
Filter on site
Cool , 4°C
Cool , 4°C
Cool, 4°C
Cool, 4°C
Cool , 4°C
None Req.
HN03 to pH < 2
Cool, 4°C
Cool , 4°C
Cool, 4°C
2 ml zinc
acetate
Cool, 4°C
Det. on site
Cool , 4°C
Cool, 4°C
Holding
time'
24 hrsd
24 hrsd
24 hrsd
24 hrsd
7 days
7 days
7 days
7 days
24 hrs
6 months
7 days
24 hrse
7 days
24 hrs
24 hrs
None
24 hrs
7 days
Standard
Method
NumberS
4E5
208
208
318
426
205
427
428
429
212
206
214
a More specific instructions for |>rusurv,ition and vimpl Iny aru found with
ej^ft procedure as detailed in the literature [1]. A general discussion
on sampling water and industrial wastewater may be found in ASTM, Part
23, p. 72-91 (1973).
b Plastic or glass
c If samples cannot be returned to the laboratory in less than 6 hrs and
holding time exceeds this limit, the final reported data should indi-
cate the actual holding time.
d Mercuric chloride may be used as an alternate preservation at a concen-
tration of 40 mg/1, especially if a longer holding time is required.
However, the use of mercuris chloride is discouraged whenever pos-
sible.
e If the sample is stabilized by cooling, it should be warmed to 25°C for
reading or temperature correction made and results reported at 25°C.
f It has been shown that samples properly preserved may be held for
extended periods beyond the recommended holding time.
9 The numbers in this column refer to the appropriate parts of the
"standard Methods for the Examination of Water and Wastewater, 14th
edition. APHA-AWWA-WPCF, 1975.
7-15
-------
Selection of surface water sampling stations, equipment, and procedures
should follow a methodical approach similar to that described for
groundwater monitoring. Each surface water monitoring item should be
evaluated in terms of compatabil ity or possible contamination with the
constituents to be analyzed.
Surface sampling stations should be located in areas which represent the
greatest potential for contamination. These points can be determined
after examining the pathways available for leachates to enter a surface
water body. Consideration should also be given to selecting stations
which can provide consistent samples throughout the monitoring program.
Flow patterns and seasonal variations should be addressed when appli-
cable.
Surface water sampling equipment should be suited to the goals of a
particular program. Sampling equipment and procedures can range from
continuous or intermediate automated samplers to manual collection by
filling a container by hand. Manual sampling is almost always considered
to be adequate.
Indicator parameters and analytical methods used for surface water
samples should be consistent with selected procedures for groundwater
sample testing. The effects of surface water mixing and interference
with contaminants should be considered.
7.4. Gas Monitoring
More often than not, sludge landfills are located quite distant from
structures and gas monitoring may not be required. When it is required,
the gas of major concern is methane. Methane gas in concentrations in
excess of 5% is explosive. If there are structures near the landfill
(e.g., a wastewater treatment plant, residences, etc.) a methane gas
control system should be installed and a monitoring program should be
carried out.
The sampling devices should be located in whatever direction structures
exist. Typically, sampling devices may be located near the property
boundary and off-site on the landfill side of structures in pathways most
susceptible to gas migration [18][19].
Gas sampling devices usually consist of simple, inexpensive gas probes.
The probe is usually polyethylene, copper, or stainless steel tubing.
Due to the small diameter of probes (
-------
The sample collection technique depends upon the type of sampling probe
installed. Most methods require some form of evacuation, although the
specific type may vary. The sampling frequency depends upon the
particular monitoring program. The estimated rate of movement of gas in
a particular soil may be useful for developing optimum periods. As a
minimum, if gas monitoring is required, samples should be taken at the
same time that water samples are taken. Most frequently a portable meter
is used to monitor methane gas. This instrument indicates the percentage
of methane gas up to the lower explosive limit of 5% methane.
7.5 References
1. Procedures Manual for Groundwater Monitoring at Solid Waste Disposal
Facilities. U.S. Environmental Protection Agency. EPA-530/SW-611.
August 1977.
2. Manual of Water Well Construction Practices. U.S. Environmental
Protection Agency. EPA-570/9-75-001. September 1975.
3. Campbell, M.D. and J.H. Lehr. Water Well Technology. McGraw-Hill
Book Company. 1974.
4. Evertte, L.G., et al. Monitoring Groundwater Quality: Costs and
Methods. Environmental Protection Agency. EPA 600/4-76-023. May
1976.
5. McMillon, L.G. and J.W. Keeley. Sampling Equipment for Groundwater
Investigations. Groundwater. 8(3):10-15, 1970.
6. SCS Engineers. Investigation of Groundwater Contamination from
Subsurface Sewage Sludge Disosal. Vol. 1: Project Descriptions and
Findings. Final Report submitted to U.S. Environmental Protection
Agency, Washington, D.C. Contract No. 68-01-4166. May 1978.
7. Wehran Engineering Corporation. Procedures Manual for Monitoring
Solid Waste Disposal Sites. Environmental Protection Agency. Office
of Solid Waste Management Programs. 1976.
8. Parizek, R.R. Site Selection Criteria for Wastewater Disposal-Soils
and Hydrogeologic Considerations. In: Recycling of Treatment
Municipal Wastewater and Sludge through Forest and Cropland. Sopper,
W.E. and L.T. Kardos (ed.). EPA-660/2-74-003. March 1974. pp.
95-130.
9. Tinlin, R.M. (ed.). Monitoring Groundwater Quality: Illustrative
Examples. Environmental Protection Agency. EPA 600/4-76-036. July
1976.
10. Battelle Pacific Northwest Laboratories. Geothermal Water and Gas-
collected Methods for Sampling and Analysis. August 1976.
7-17
-------
11. Methods for Chemical Analysis of Waste and Water. U.S. Environmental
Protection Agency. EPA-625/6-74-003. June 1974.
12. American Public Health Association. Standard Methods for the Exa-
mination of Waste and Wastewater. 14th Edition, 1975.
13. Sommerfeldt, T.G. and D.E. Campbell. A Pneumatic System to Pump
Water from Piezometers. Groundwater. 13(3):293, 1975.
14. Trescott, P.C. and G.F. Pinder. Air Pump for Small-Diameter
Piezometers. Groundwater 8(3):10-15, 1970.
15. Quality Criteria for Water. U.S. Environmental Protection Agency.
EPA 440/9-76-023. July 1976.
16. David, F.N. and R.J.M. DeWiest. Hydrogeology. John Wiley & Sons,
New York. 1966.
17. Handbook for Monitoring Industrial Wastewater. U.S. Environmental
Protection Agency. Technology Transfer. Report No.
EPA-625/6-73-002. August 1973. pp. 5-14.
18. Engineering-Science, Inc. J_n Situ Investigation of Movements of
Gases Produced from Decompositing Refuse. APWA Special Report, No.
29, February 1964.
19. Esmaili, H. Control of Gas Flow from Sanitary Landfills. Journal of
the Environmental Engineering Division, Proceedings of the Amer. Soc.
Civil Enginerers. August 1975. pp. 555-566.
20. Anderson* D.R. and J.P. Callinan. Gas Generation and Movement in
Landfills. Loyola University of Los Angeles.
7-18
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CHAPTER 8
COMPLETED SITE
8.1 Introduction
The purpose of this chapter is to provide guidance in developing a com-
pleted site plan. This plan should be first considered during the site
selection process and finalized during the design process. Objectives of
a completed site plan include:
1. Designate the operational procedures for site closure
2. Establish the criteria that must be addressed before planning the
final site use
3. Determine the components of final site use that will ultimately
lead to the selection of a site use that is publicly acceptable
as well as technically practical
A plan for the final use of the landfill is a step toward acceptance of a
proposed site. This is particularly true where there is active public
participation in the site selection process. The local landfill should
be shown to represent an immediate and future benefit to the community.
On the other hand, projected site uses should be realistic both in
concept and in the method portrayed.
Final site uses may have a longer life than the original filling opera-
tion. Because of the long-term nature of the final use, the completed
site plan should be prepared at the same time that the landfill is being
designed, since decisions regarding one can substantially affect the
other. Each step of the landfill process—initial site preparation,
installations of screening and buffers, placement of the final landfill
cover, and revegetation--should be seen as steps toward achieving the
final use [1].
By integrating the final site plans into the preliminary design, the
ultimate value and cost of developing the final site can be enhanced.
Leaving islands of undisturbed soil in strategic areas will enable the
site to be developed and increase the overall value of the site. Setting
aside part of the operating fees for final site development can provide
the capital needed for site closure. If the land is to be sold, the
question of liability and responsibility for regrading and monitoring
8-1
-------
should be considered. In New York, for instance, the landfill operator
is responsible for monitoring and maintenance for 5 years after site
closure regardless of whether he has sold the property or not [2].
However, in California the current property owner is usually held liable
in court cases.
8.2 Procedures for Site Closure
The following operational procedures for closing a site are to be
performed when either the entire sludge landfill or a segment of the
landfill has been filled to capacity. These procedures can be conducted
concurrent with on-going site operation. Procedures for proper site
closure are outlined in Table 8-1.
TABLE 8-1
PROCEDURES FOR SITE CLOSURE
• No sludge should be left exposed. Trenches and lifts should be
sufficiently covered. If trenches and lifts are unstable, they
should be well marked using drums or wooden barricades.
i Although the rate of settling varies, maximum settlement will
occur within the first year of landfill ing. Accordingly, suffi-
cient time should be allowed for the area to settle. As neces-
sary, the area should be regraded to account for settlement.
• After maximum settlement has occurred, the area should be re-
graded to ensure proper drainage. Depressions and cracks should
be filled using on-site or borrowed soil. Bulldozers and/or
graders are normally used for spreading and grading the soil.
• One to 3 ft (0.3 to 0.9 m) of final cover may be applied. This
cover may consist of top soil which was stripped and stockpiled
prior to commencing the landfill ing operation. Soil that is
deficient in organics (e.g., sandy soil) may require a mixture of
sludge at a ratio of 5:1 to 10:1.
• Check sediment and erosion controls and modify according to any
change in grade.
* Construction of small structures (picnic tables shelters, etc.)
may be undertaken in accordance with specifications in the final
site use plan.
• Disassemble temporary structures and receiving areas not required
for final site use.
• Hydroseed denuded areas with the appropriate mixture of grasses.
Climate and final site use are a major factor in determining the
type of grass and vegetation selected.
» Outline a timetable to ensure that the following features are in-
spected at regular intervals:
1. Settlement, cover soil integrity, and need for grading
2. Buffers and vegetation
3. Sediment and erosion control facilities
4. Fencing
5. Leachate and gas controls
6. Integrity of final site use facility
7. Vandalism
8. Monitoring
8-2
-------
For several years after filling is completed the site should be inspected
at monthly to quarterly intervals, as outlined in Table 8-1. Thereafter,
inspection should be conducted at least annually. Additionally, sediment
and erosion controls should be inspected during rainy periods to
determine their effectiveness.
Upon completion of the site, a plan detailing the site development,
operation, and controls should be prepared and recorded with the county
records. The description should include general types and locations of
wastes, depth of fill, and other information of interest to potential
landowners [1].
8.3 Characteristics of Completed Site
When planning a final site use, critical factors that must be considered
are settlement, bearing capacity, final grade, and control of leachate
and gas, and vegetation [3].
8.3.1 Settlement
Settlement due to the volume reduction of sludge creates cracks or fis-
sures in the cover material. It can contribute to substantial movement
in the verticial and/or the horizontal direction, with displacements
ranging from 6 in. (15 cm) to 3 ft (0.9 m). Settlement can occur within
a few days of filling or can extend over many years. Experience has
indicated that the site may have to be regraded up to 3, 4, or 5 years
after closure. Research has been conducted in the laboratory on the
settlement of landfilled paper mill sludges [4][5], but additional work
is needed in order to predict the settlement of landfilled municipal
sludges.
The rate and extent of settlement are controlled by the interaction of a
number of variables, including:
1. Sludge characteristics
2. Landfill ing method
3. Soil characteristics
Of these, the characteristics of the sludge have the greatest impact
8-3
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8.3.1.1 Sludge Characteristics
Relevant sludge charcteristics include:
1. Sol ids content
2. Volatile solids content
3. Particle size and configuration
A detailed discussion of treatment processes and resulting sludge types
has been included previously. Sludge with a low solids content (15-20%
solids) can be expected to settle more than sludge with a higher solids
content (>28% solids). Sludge may dewater through evaporation, infiltra-
tion (into porous soils) or separation; but in any case, as it loses
moisture, the pore spaces increase. The result is a loss of volume and
consequent settling.
Other factors that influence the stability of the completed site are the
volatile solids content and the size and configuration of sludge par-
ticles. In general, the higher the volatile solids content, the greater
the degree of settlement. Sludges with large, poorly sorted particles
will also settle to a greater extent.
8.3.1.2 Landfill ing Method
The landfill ing method influences the potential for settlement. Landfil-
ling methods that call for the mixture of sludge with soil or refuse
settle in a different fashion than a method using only sludge.
Sludge with a lower solids content disposed in trenches may stratify into
liquid and solid phases. The solids may settle to the bottom of the
trench, resulting in a liquid layer forming at the top. If this separa-
tion occurs, rapid settlement of the solid fraction results. Conversely,
stratification may occur where solids rise to the surface. This buoyant
effect is caused by gases of decomposition which adhere to sludge
solids.
Area fill landfills (where the sludge is not contained) may experience
horizontal movement or creeping. Area fill methods are also more
susceptible to variable climatic conditions, which also affect landfill
stability.
8-4
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8.3.1.3 Soil Characteristics
The amount of interim and final cover affects the degree of settlement.
Often termed surcharge, the cover enhances percolation of liquid into the
surrounding soil by applying pressure on the sludge. The ability of the
cover material to bear weight, inhibit water infiltration, and hold
vegetation is important when predicting sludge settlement. Soil used for
sludge bulking also affects the settling potential.
8.3.2 Bearing Capacity
The bearing capacity of a completed landfill is the measure of its abil-
ity to support foundations. The bearing capacity of the sludge landfill
is dependent on the following:
1. Sludge characteristics
2. Landfill ing method
3. Soil characteristics (bulking and cover)
4. Vegetation
Currently, limited information is available on the bearing capacity of
sludge landfills. Although laboratory scale sludge bearing tests have
been conducted on industrial wastewater sludges and solid waste, it is
questionable whether these tests are valid on a large-scale municipal
wastewater sludge landfill over long periods of time. Although natural
soils produce bearing test values that fall within a predictable range
and are reproducible, it is not known whether tests on sludge will
produce similar results. Therefore, it is suggested that construction of
structures on a sludge landfill site be restricted to areas of
undisturbed soils where landfill ing of sludge has not occurred.
8.3.3 Final Grade
The final slopes in the landfill should generally range from 2 to 5%.
Factors that influence the final grade are:
1. Climate
2. Vegetation
3. Soil characteristics
8-5
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In relatively dry climates with suitable vegetative cover, slopes may
safely exceed 5%. On the other hand, in areas with high rainfalls it may
be necessary to use extensive erosion and drainage control for slopes
above 5%.
8.3.4 Leachate and Gas
Leachate and gas from sludge landfills will continue to be produced long
after the fill is completed. If not properly controlled, gas can accumu-
late in enclosed areas or structures. Also, at certain concentrations
gas can stunt or kill vegetation. Leachate can cause serious pollution
of groundwater and surface water if not properly controlled.
An impermeable cap placed over a sludge landfill after completion will
decrease the potential for leachate by decreasing the amount of surface
water infiltration. Gas and leachate controls must be incorporated into
the design (see Chapter 5, Design).
8.3.5 Vegetation
In most instances, a completed site will require some vegetation.
Through careful selection, plants can enhance the attenuative properties
of the soil as well as perform the traditional functions of erosion con-
trol, infiltration management (see Figure 8-1), and visual enhancement.
Winter rye has been found to be effective in enhancing the fertility of
the soil. It has the advantage of quick growth and hence can provide
effective early erosion control. If planted with bermuda grass it can
serve to stabilize slopes and reduce runoff. Bunch grasses, such as
canary grass, and sod grasses generally provide good cover and grow well
in conditions found in landfills. Where stabilized sludge has been
landfilled, trees can be planted and will generally do well. Information
concerning suitable cover crops is available from the U.S. Department of
Agriculture, Soil Conservation Service. In addition, local agencies such
as county extension services and local universities are valuable sources
of data.
8.4 Completed Site Use
The selection and design of final land uses should be the result of a
comprehensive land planning study that considers all aspects of proposed
filling operations as well as final uses. The objectives of the land
planning study should be to identify uses that will:
8-6
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FIGURE 8-1
INFILTRATION RATES FOR VARIOUS CROPS
2.8
0.0
OLD PERMANENT
PASTURE OR HEAVY
MULCH
4-8 YEAR OLD
PERMANENT PASTURE
3-4 YEAR OLD
PERMANENT PASTURE
LIGHTLY GRAZED
PERMANENT PASTURE
MODERATELY GRAZED
HAYS
PERMANENT PASTURE
HEAVILY GRAZED
STRIP CROPPED OR
MIXED COVER
WEEDS OR GRAIN
CLEAN TILLED
BARE GROUND
CRUSTED
10
ZO 30
TIME, mln.
40
50
60
1. Take advantage of the opportunity for permanent improvements to
the landfill that are available after filling is completed
2. Eliminate or minimize potential off-site conflicts with existing
or future development through the careful siting of the fill,
maintenance of an open space separation, and utilization of
natural screening and buffers
3. Be compatible with and complementary to existing natural condi-
tions and activities and help meet the future needs of the com-
munity
The land planning process should be integrated with site selection and be
carefully organized to seek out relevant information relating to the
site. Four important steps to follow are:
8-7
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1. Perform site inventory. The existing land use must be identified
and the impact of curtailment of current land use (whether it be
recreation, open space, etc.) must be determined. The inventory
might include topography, vegetation, water bodies, public faci-
lities, etc. Information can be obtained from aerial photos,
site visits, and review of public records.
2. Evaluate of Needs. To assess future needs, an evaluation of
localplansforpopulation, utility, and highway projections
should be attempted. Local planning offices should be contacted
to determine current land use policies for the area of
consideration.
3. Identify alternatives and select completed site use. Using the
information obtained above, an evaluation should be conducted
noting advantages and disadvantages of each potential use. If
site characteristics and constraints are known, alternative
ultimate land uses can be evaluated in terms of technical
feasibility and costs. The optimum site use can then be
selected.
4. Select, design, and implement completed site use. After se-
lecting completed site use, a master plan should be prepared.
It should designate the scheme for cover soil stockpiling,
maintaining positive drainage by regrading, revegetation, sedi-
ment control, leachate control, ground or surface water moni-
toring, and maintaining acceptable environmental and aesthetic
conditions.
8.5 References
1. Sanitary Landfill Manual of Practice, No. 39. American Society of
Civil Engineers, Environmental Engineering Division, Solid Waste
Management Committee. 1976.
2. New York State Compilation of 'Rules and Regulations, Part 360, Solid
Waste Management Facilities.
3. Brunner, D. R. and D. J. Keller. Sanitary Landfill Design and
Operation. U.S. Environmental Protection Agency. Report No.
SW-65ts. 1972.
4. Noble, G. Designing for Final Use of the Landfill. (Presented for
Course in Sanitary Landfill Site Selection, Design and Operation at
the University of Wisconsin - Extension, Department of Engineering).
April 1977. pp. 4.
5. Leadbetter, R. H. Design Considerations for Pulp and Paper mill
Sludge Landfills, U.S. Army Corps of Engineers, Waterways Experiment
Station. (Prepared for Municipal Environmental Research Laboratory,
Cincinnati, OH). December 1976. pp. 136.
6. Process Design Manual for Land Treatment of Municipal Wastewater.
U.S. Environmental Protection Agency, Technology Transfer. Report
No. EPA 625/1-77-008. October 1977. pp. 5-81.
8-8
-------
CHAPTER 9
MANAGEMENT AND COSTS
9.1 Introduction
The operation of a sludge landfill is dependent upon a number of factors
including the volume and type of sludge received and site conditions. It
is the intent of good landfill administration to efficiently manage these
factors in a way which adequately protect the environment. However, due
to more stringent regulations and spiral ing construction costs, the
operation of a sludge landfill is becoming increasingly costly.
Management of a sludge landfill involves a wide range of responsibilities
and requires a number of specialties. The landfill manager has opera-
tional responsibilities (conformance to the design and regulations,
day-to-day operation, security, and equipment maintenance and replace-
ment); social responsibilities (public relations and personnel hiring,
training, and safety); and fiscal responsiblities (equipment and
personnel recordkeeping, operational recordkeeping, budgets, and
financing). Managers of sludge landfills should become involved in the
project early in its planning stage. Continuity of management is
desirable throughout the operating life of the landfill.
9.2 Management Responsibility
Operation of sludge landfills may be under public or private management.
A description of typical alternative managing organizations is detailed
below.
9.2.1 Municipal Operations
Most sludge landfills are municipal operations. Authority for operating
and managing such landfills is usually entrusted either to the sewer
department or to the department of public works. Sewer departments often
manage sludge landfills since wastes received at that sites are generated
by treatment plants owned by sewer departments. Disposal of residuals is
part of the wastewater treatment process at large, and costs incurred are
usually financed through sewer fees. Also, vehicles used to haul sludge
are often owned and operated by the sewer department. Finally, many
sludge landfills are located at or near the treatment plant, and the
property is owned by the sewer department.
9-1
-------
However, management of sludge landfills is increasingly being assumed by
public works departments. This may be more appropriate, particularly
when landfills are not located on the treatment plant property since
operation of a sludge landfill is a construction activity that is well-
suited to the experience and resources of public works departments.
9.2.2 County Operations
Management of sludge landfills by county governments is less prevalent
than that of municipal governments. As with municipal operations, county
landfills are often managed either by the sewer department or by the
public works department. However, County landfills usually serve larger
populations and geographic regions than municipal landfills and the
attendant economies of scale and the greater land areas available may
make such operations more desirable than municipally-managed sludge
landfills. The choice of county or municipal management usually is
determined by whether the sewer department is administered by the
municipality or the county. Nevertheless, due to the potential
advantages of county-wide sludge landfills management, this should be
considered even when sewage is treated by several municipalities.
9.2.3 Sanitary District Operations
Sanitary districts are more likely to be responsible for managing sludge
landfills than are their municipal counterparts (sewer departments) since
no alternative authority is available. Financing for sludge landfills
managed by sanitary districts is often easier to secure since they may
have provisions for levying special taxes. Also, these districts gen-
erally service greater populations and may serve several jurisdictions.
As a result, sanitary districts are generally better financed and equip-
ped to operate sludge landfills due to the economies of scale.
9.2.4 Private Operations
Next to municipal operations, privately-managed operations are the most
prevalent type of sludge landfill. Sludge landfills may be operated
under contract, franchise, or permit arrangement. In contract opera-
tions, the presiding government agency contracts with the private opera-
tor to dispose of sludge for a fixed lump sum fee or for a unit charge
per ton, cubic yard, or truck load. If a unit charge is the basis of the
contractual arrangement, the government agency usually guarantees a
specified minimum dollar amount to the contractor. Franchises usually
grant the operator permission to dispose of sludge from specified areas
and charge regulated fees. Permits allow the operator to accept sludge
for disposal without regard to source.
9-2
-------
Private operations may benefit government agencies that have limited
capita"! available for construction and initial operation of a sludge
landfill. Also, private operators may be able to operate at a lower
cost. However, precautions should be taken to ensure that private
operators will provide adequate environmental safeguards. For this
reason, contract arrangements are usually the best choice since operating
and performance standards can be written into the contract.
9.3 Equipment Management and Documentation
Equipment cost is the largest single expense incurred in the operation of
most sludge landfills, exceeding even the labor cost. Accordingly, the
proper selection, purchase, operation, and maintenance of equipment will
contribute substantially to the cost efficiency of a landfill. Following
are some important facets to consider in managing equipment at sludge
landfil 1 s.
9.3.1 Selection and Purchase
A determination of the type and number of machines needed to operate a
sludge landfill is a function of production (speed at which the equipment
can accomplish an assigned task when operated appropriately), size of the
site, quantity of sludge handled, landfilling method, types of soil, and
availability of parts and service. Guidance was provided in Chapter 6
(Operation) on the selection of equipment under various conditions. It
should be remembered, however, that a determination of equipment needs
for an actual sludge landfill should be made on a case-by-case basis.
Having chosen appropriate equipment, the following cost categories should
be considered prior to purchasing:
1. Owning cost. This consists of the price of the equipment, the
interest charges, the taxes, and the insurance premium.
2. Operating cost. This includes costs for maintenance and fuel.
Maintenance costs must include not only repairs, but also the
price of oil, grease, and labor for preventive maintenance.
3. Downtime cost. Every effort must be made to keep this cost to a
minimum. Standby equipment cost must also be considered here.
Since the operation must continue when a machine is down, back-up
equipment will be needed. Equipment rentals may be appropriate.
9-3
-------
4. Resale value. This includes the depreciation rate on the machine
and what its potential market value may be when the equipment is
no longer needed.
Consideration of all of the above cost factors will enable managers of
sludge landfills to get a complete picture of the actual total equipment
cost. In addition to the purchase cost, operating and downtime costs
must be included in any cost analysis. These can amount to a substantial
percentage of the owning cost over the life of the sludge landfill. Of
course, the landfill manager can recoup some costs through resale of the
equipment.
9.3.2 Operation
The nucleus of the sludge landfill operation is the equipment. To
maximize efficiency, prevent equipment damage and personal injury, and
ensure an environmentally sound and economical operation, equipment
should only be operated by competent and qualified personnel. Ac-
cordingly, operators should have extensive experience in equipment
operation. If new equipment operators are trained at sludge landfills, a
qualified operator should ride along until the employee is thoroughly
competent on the machine and the new operator should be checked and
tested by the supervisor before a machine assignment is made. Operators
should work cautiously at sludge landfills, since the unstable nature of
sludge can cause equipment operated by even the most experienced
personnel to become mired in sludge. After some experience, however,
operators can learn to use their equipment more efficiently in the
landfill environment.
9.3.3 Maintenance
Often equipment maintenance is more expensive than the amortized annual
cost of equipment purchase. Thus, equipment maintenance is a high-cost
item and constitutes a substantial part of the on-going operational
expense of sludge landfills.
Initially, a sludge landfill manager should outline a comprehensive
preventive maintenance program. If preventive maintenance is performed
daily, the manager has taken a major step toward lowering maintenance
costs. Normally, the equipment operator performs routine maintenance
each day on his machine; e.g., checking water and oil, lubrication,
keeping tracks clean, blowing out radiators with an air compressor, etc.
It is critical that these maintenance tasks be performed daily, and the
9-4
-------
supervisor should be personally responsible for ensuring that these tasks
are performed. In some larger landfill operations, a full-time or
part-time mechanic is assigned to perform maintenance and repairs of all
of the landfill equipment.
Sludge landfill managers should make sure that the operation manual for
each piece of equipment is readily available. Machine operators should
consult the manuals in order to be familiar with the daily service needs
of their equipment. These manuals should also be available to mechanics
to ascertain the specific service requirements for each piece of equip-
ment.
Equipment with a maintenance warranty will provide guidelines for mainte-
nance that should be strictly followed to preserve the warranty for the
designated period. Failure to adhere to these guidelines could increase
maintenance costs.
9.3.4 Recordkeeping
A daily report should be completed by the operator for the equipment that
he has operated that day. Sludge landfill managers should ensure that
these records are complete, up to date, and accessible. The objective is
both to ensure more complete maintenance and to lower maintenance costs.
A sample form to be completed for this task has been included as Figure
9-1.
9.4 Personnel Management and Recordkeeping
Next to equipment, personnel is usually the largest single expense in
a sludge landfill operation. Careful screening and hiring of employees
and subsequent training of personnel develops an efficient operation. A
safety program should be instituted as part of initial personnel training
and conducted thereafter on an on-going basis. A detailed description of
personnel management practices is included below.
9.4.1 Personnel Requirements and Hiring Practices
A description of personnel positions at sludge landfills and an overview
of personnel requirements was described earlier in Chapter 6 (Operation).
The most prevalent position at sludge landfills is that of equipment
operator. For most sites, the number of personnel will be equal to or
less than the number of machines. Often one person can be used to
9-5
-------
FIGURE 9-1
EQUIPMENT INSPECTION FORM [1]
Site:
Machine:
Date:
Completed By:
Hour Meter Reading:
BEFORE STARTING CHECK
WATER Q
F.NG. OIL D
TRANS. Q
PU£L g
WATES ADDED MONT Q
ENG.OIL ADDED FRONT Q
TRANS.OIL ADDED FRONT Q
HYDRAULIC OIL ADDED t-i
FRONT U
AFTER STARTING LEVEL MACHINE AND CHECK
WATER ADDED REAR O
" ENG.OIL ADDED REAR O
" T«AN5.OIL ADDED REAR Q
FINAL DRIVE OIL r]
ENGINE OIL
TRANS.
HYDRAULIC OIL
ANY LEAKS
BRAKES
STEERING
TRANSMISSION
PRESSURE
GAUGES
SHIFTING
ENGINE
TEMP.
OIL PRESSURE
WATER TEMP.
UNDERCARRIAGE
TRACK ADJUST.
ROLLER WEAR
TIRES
BLADE
CUTTING EDGES
TRUNNIONS
HYDRAULICS
PUMP
JACKS
OTHER
AIR CLEANERS
RAD. CLEAN
TRACK CLEAN
TIRES FREE OF MU
Q
D
n
D
n
n
Q
a
n
Q
a
a
n
o
a
n
Q
a
n
Q
D
i~l
a
a
n
n
ID ^
operate two or more machines (since 100% utilization of all equipment is
often not required). For the larger sites, especially codisposal sites,
the number of personnel may exceed the number of equipment pieces. These
surplus personnel may be on-site superintendents, equipment mechanics,
laborers, or check station
superintendents,
attendants.
9-6
-------
Hiring should be done in compliance with equal employment opportunity and
nondiscrimination-in-hiring practices. When considering an applicant for
a position, these procedures should be followed:
1. The applicant should complete an employment application form.
2. Supervisors should personally interview each applicant. The
applicant should be questioned closely on past work experience
to determine qualifications. The importance of the job should
be explained fully with emphasis on the need to maintain a
sanitary condition and to prevent environmental degradation.
3. The applicant's past employers and character references should
be checked and the applicant's reliability and work record
determined. The applicant's statements concerning experience
and qualifications should be verified. Tests to determine the
applicant's ability to perform the work are highly desirable.
4. If a decision is made to hire, arrangements should be made for
the applicant to be given a thorough physical examination.
These hiring practices will help achieve a high standard for new
employees.
9.4.2 Training
New employees should not only learn the tasks required for their posi-
tions, but also understand the purposes and importance of the sludge
landfill ing operation. Except for the largest operations, comprehensive
training programs are not likely to be designed or conducted by landfill
management. Training Programs have been prepared for refuse landfills by
the U.S. Environmental Protection Agency, the American Public Works
Association, and various educational institutions [1][2][3]. Since many
of the procedures employed at refuse landfills are similar or identical
to those employed at sludge landfills, these programs can be useful.
Programs may take the form of classes conducted by these agencies or the
provision of guideline information for training activities conducted for
the employees. Equipment manufacturers are another valuable source of
information on training procedures.
9.4.3 Safety
Managers of sludge landfill operations have an obligation to maintain
safe and secure working conditions for all landfill personnel and also to
9-7
-------
see to it that safety rules are written, published, and given to each
employee.
The landfill manager should establish a safety training program and
should express, by example, a commitment to that program. Ideally, one
man should be assigned the task of conducting the program and in
assessing the compliance and efficacy of the program. A supervisor or
foreman, because of his proximity to the operation is the logical choice
for this position.
A safety checklist prepared by the National Solid Waste Management
Association has been included as Figure 9-2. Although this checklist was
prepared for municipal refuse landfills, most of the items are relevant
to sludge landfill operations.
Privately operated landfills are required by Federal law to maintain
up-to-date Occupational Safety and Health Act (OSHA) form records and to
post the current OSHA employment poster. When an inspection is made of
the landfill, the inspector will request to see all of the OSHA record-
keeping forms. If they are not up to date, it can result in a citation
and fines. Any records on safety meetings and preventive maintenance, as
well as posters and brochures, will be considered by an inspector as an
act of good faith and will indicate that an effort is being made to
comply.
9.5 General Management and Recordkeeping
In addition to direction of equipment and personnel, a manager has
numerous other responsibilities which must be performed to ensure a safe
and efficient operation. These include the completion of activity
records, the evaluation of operational performance, on-site supervision,
public relations, and security. More details on these tasks are outlined
below.
9.5.1 Activity Records
Complete records of the activity at sludge landfills may be needed either
(1) to compile waste receipt records for billing purposes; (2) to assess
the rate of cover utilization for future stockpiling needs; and/or (3) to
gauge the overall efficiency of the landfill. Figure 9-3 is a sample
form which could be used to record the quantity of sludge received from
each incoming truck on a single day. If this information is available
from the wastewater treatment plant, that data may be used. The daily
sludge quantity can be totaled at the bottom of the daily form and
9-8
-------
FIGURE 9-2
LANDFILL SAFETY CHECKLIST [2]
c
- —
1.
2.
3.
4.
5.
6.
BUILDING EXITS (OSHA 1910.35 - 1910.37)
Doors swing with exit travel
Marked with lighted signi
Not locked so that they may be used From the inside at all times
Keep free of obstructions
Non-exit doors which can be mistaken as an exit as an exit are marked "No Exit"
Single exits are allowed for rooms containing less than 25 people
ombustible, Oxidizing, and Flammable Agents, When Using (OSHA 1910. 101 -1910. 1 16)
7.
8.
9.
10.
11.
12.
13.
U.
15.
16.
17.
18.
Electrical installation and static electricity are controlled or maintained
Heating appliances are controlled or maintained in a safe manner
"Hot" work (welding) controlled or maintained in a safe manner
At least one 20 pound Gloss B fire extinguisher is within 25 fe«t of a storage area
ICC approved metal drums are used for storage from 5-60 gallons
Not more than required for one do/ or shift stored outside storage cabinet
COMPRESSED AND LIQUIFIE& GASES (OSHA 1916.101-1910. 1 16)
Charged and empty cylinders ore separated
Cylinders are grouped by type and stored in vertical positions
Cylinders ore not stored near other combustible material
Cylinders are supported so that they cannot be tipped over
Cylinder caps are in place on all cylinders which are not in use
Oxygen cylinders are not stored within 20 feet of other types of gases
DRAINAGE
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
Drains are vented to prevent collection of combustible gases
Grease and oil prevented from entering public sewage systems
ELE^TftiCAI. EQUIPMENT (OSHA 1*10.308-1*10. 3<») '
All outlet and junction boxes are properly covered
All portable electrical tools and appliances are properly grounded
Records maintained for inspection or portable electrical tools and appliances
Electrical cabinet doors with exposed conductors of 50 volts or more are securely fastened
Enclosures around high voltage electrical equipment ore marked
Frayed cords, cobles, and loose wires regularly removed from service
Switch boxes ore identified as to equipment they control
EMERGENCY LIGHTING
Exit signs are illuminated to at least 5 foot candles
FIRE EXTINGUISHER EQUIPMENT (OSHA 1910.157)
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
5?
—
—
33.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
Extinguishers are inspected monthly for physical damage
Inspection records ore kept indicating inspector
Maintenance performed yearly; hydrotested every 5 years, if required
Inspection togs marked by month and year
Extinguishers conspicuously installed and properly marked for use by type of Fire (A,B,CorD)
The top of portable extinguishers (less than 40 Ibs) mounted no more than 5* above the floor
The top of portable extinguishers (40 Ibs or more) mounted no more than 3-1/2' above the floor
FIRST AID (OSHA 1910.151)
An approved first aid kit is available
Emergency numbers of company-approved doctors and hospitals posted in appropriate locations
Trained personnel available
HAND AND PORTABLE TOOLS (OSHA 1910.241-1910.247)
All useable tools have guards properly installed
All portable electrical tools are tested monthly for ground
Records kept of inspection (item 41)
Atl tools in safe operating condition are free from worn or defective parts
Jocks and hoists are legibly marked with the load rating
HOUSEKEEPING
Material on walls/shelves stored in a safe and orderly manner
Facility is in a clean, orderly, and sanitary condition
Hoses, welding leads, drop lights, etc. ore rolled and properly stored
Permanent aisles and passageways are Free of obstructions
Permanent aisles and passageways are permanently marked
ILLUMINATION
Sufficient quantity (20 foot candles or greater)
Uniform distribution
W.I! H;r»<-t«d
INDUSTRIAL SANITATION (OSHA 1910.14]']
Clean, available drinking fountains
Facilities ore maintained in o clean and stocked condition
Hot water available
Individual towels and drinking cups available
Toilet facilities ore within 200 feet of working area for each sex
INDUSTRIAL TRUCK- FORKLIFT (OSHA 1910.178)
Brakes in good operating condition
Guord behind fork is in place (to guard from load falling to the rear)
Load capacity of truck marked
No one except operator permitted to ride
No one stands or walks under raised Forks
Overhead guard to protect against foiling objects
Recharging/reFueling done in a "No Smoking" isolated area
Training program for operators
Warning devices (horn) working
LADDERS (OSHA 1910.25-1910.28)
Anti-slip safety steps used on portable ladders
Caution exercised when metal ladders used in electric current areas
Caution exercised when metal ladders used with portable electric tools
Ladders inspected monthly with inspection records kept
Straight ladders properly secured
9-9
-------
FIGURE 9-2 (Continued)
UQU!D PETROL£UM~
LKjJUMJI rEIKULCU/V OAaE^fOSHA 191IX I 10)
72. Bulk storage (126 to 500 gallons) at least 10 feet from building
73. Bulk storage (501 to 2,000 gallons) at least 25 feet from building
74. Bulk storage (251 to 2,000 gallons) at least three feet separation between tanks
75. Containers labeled by size (in pounds or gallon^
76. Containers labeled with pressure in "gauge psi"
77. Containers labeled by type of L.P.G.
78. Containers have safety relief and shut-off valves
79. Containers stored away from exits
80. Distance between C.P.G. containers and flammable liquid containers is 20 feet
81. No containers are stacked one above the other
82. Container! ore stored in a "No Smoking" area
MACHINE GUARDING (OSHA 1910.211-1910.222)
83 ~Abrasive wheels in accordance with type of work
84. Abrasive wheels In good condition
85. Abrasive wheels labeled and in accordance with rpm ratings
86. Abrasive wheels uniform In diameters
8~. Air nozzles used for cleaning meet 30 psl limit
88. AH rotating, cutting shearing, screw and worm, blending, and forming motions guarded
89. Safety precautions understood and used by shop employees
90. Steady rests on grinders meet^l/8" adjustment to wheel requirement
PERSONAL PROTECTIVE EQUIPMENT (OSHA 1910.95, 1910.132-1910.140)
91. All protective equipment maintained in safe working condition
92. Ear protection worn when noise dBA greater than 90 for 8 hours
93. Ear protection worn when noise dBA greater than 95 for 4 hours
94. Ear protection worn when noise dBA greater than 100 for 2 hours
95. Ear protection worn when noise dBA greater than 105 far 1 hour
96. Ear protection worn when noise dBA greater than 110 for 1/2 hour
97. Ear protection worn when noise dBA greater than 115 for 1/4 hour
98. Eye ond face protection provided where reasonable probability of injury exists
99. Respiratory protective equipment worn when air It contaminated (dust, gases, etc.)
1 DO. Safety shoes, caps, gloves worn when necessary
STAIRS (OSHA 1910.21-1910.24)
Angle of rise is between 30 to 50 degrees
Fixed stairs have at least a 22" width
Fixed stairs have at least a 1000 fbs. load strength
Non-slip treads are present
Stair railings are 30-34" from top rail surface to forward edge of step
Stairways less than 44" wide (both sides enclosed) have at least one handrail
Stairways less than 44" wide 'one side open) have at least one stair railing on open side
Stairways over 44" wide (both sides open) have two railings
Standard railings are 42" nominally from top surface of floor
Wood railing posts at least 2" x 4" stock spaced not to exceed 6 feet
Pipe railings and posts at least 1-1/2" nominal diameter
Pipe railing posts spaced not to exceed 8 feet
Structural steet railings end posts at 'east 2" x 2"
Structural steel railing posts spaced not^o exceed 8 feet j
VENTILATION (OS'HA 1910.94)
115. Exhouit system fo^ removal oF toxic fumes and dust from work area
WALKING, WORKING SURFACES (OSHA 1910.21-1910.32)
116. Aisles ond passageways unobstructed
117. Permanent walkways marked
118. Floor hole openings guarded and marked
119. Floor surfaces in good condition and uncluttered
WELDING, CUTTING, HEATING OR BRAZING (OSHA 1910.251-1910.254)
120. Acetylene not used at pressures greater than 15'p$Tg
121. Eye profecfion worn, where required by extant of hazard
122. During welding operations, oporeclable combustibles more than 35 feet away
123. During welding operations, floor swept clean of combustibles within 35 feet
124. Fire watch practiced, where necessary
125. Frame cf electric welding machine grounded
HEAVY EQUIPMENT SAFETY REQUIREMENTS
Each piece of equipment has roll-over protection (see Section X-"Rotl Over Protection
Schedule")
Each p'ece of equipment has fire extinguisher (20 Ibs. ABC Minimum)
All heavy equipment is equipped with backup alarm
All machines operating at night equipped with headlights
Seat belts ore onfall equipment with roll-over protection
126.
127.
128.
129.
130.
MEDICAL AND FIRST AID
~T3~T. MedTcol persofinet available for advice and consultation
132. Suitable place to render first aid
_ ROADS
133. Adjacent road (City, State, etc.Hs clear of debris and mud
134. Where possible, warning sign or light, "TRUCK ENTRANCE"
135. Landfill rood crowned and proper drainage
136. Landfill road kept properly cleaned of debris
137. Landfill rood has proper dust control by means of a water wagon or water truck
138. Traffic Control Signs (Landfill) - Stop sign (For vehicle leaving landfill before
entering public street)
139. Traffic Control Signs (Landfill) - Speed limit signs
140. Traffic Control Signs /Landfill) - No parking signs _ _
LANDFILL SITE
All u nd erg round cables, p"ip es , etc., a re ~ clearl y
rk ec( a^id rdentTfi ed~
fficient height to allow clearance for all equipment
141 .
142.
Utility wires are of
landfill
Security fences and landfill s[te
kept free as -possible of blowing paper and debris
9-10
-------
FIGURE 9-3
DAILY WASTE RECEIPT FORM
Truck
Ident.
Totals
Time*
Sludge
Sourcet
Type-t
SI udge
Weight
or
Volume
Instructions:
To be completed for each truck, each
time it makes a delivery.
Only record time at 15-minute intervals
Sources: Code for Contributing Treatment Plant
Types: G = grit; DI = digested; CT = chemically
treated
transferred to the monthly summary included as Figure 9-4.
summary can be used to record the sludge quantity received
cover soil utilization, personnel and machine hours, and
expenses.
The monthly
as well as
miscellaneous
9.5.2 Performance Evaluation
Generally, a state or local regulatory agency determines if the landfill
operation is being conducted in a manner that adequately protects the
environment. The concern of the landfill management, whether publicly or
privately operated, helps guarantee an effective operation. The
management of the organization operating the landfill should periodically
evaluate the operation. The operating and supervisory personnel should
be aware that these evaluations will be made, but the specific dates
should not be made known in advance.
9-11
-------
FIGURE 9-4
MONTHLY ACTIVITY FORM
Site:
Month:
Completed By:
Day
1
2
3
4
5
6
7
e
9
10
11
12
13
U
15
16
"
c
Sludge
Loads
,9
20
21
22
23
24
23
26
27
28
29
3C
31
Totals
Tom!
Cover material
Begin
Rec'd
Us*d
Remain
Man
hn.
Machine
hrs.
Use
Dawn
Exoe-*e
S (TVoe
Site
hn.
1
1 ton = 0.907 Mg
9.5.3 On-Site Supervision
For safety reasons, it is desirable to have two or more persons working
at sludge landfills. This can easily be accomplished at large landfills
where more than one person is needed for daily operation. On small sites
requiring only one operator, a second person should visit the site daily
or the single operator should phone or check in at the end of each day.
At a large site a foreman may be required with appropriate echelons of
subordinate supervisors. A multishift operation would require
9-12
-------
supervisors for each of the shifts as well as an overall manager. No
matter what the size of the operation, one person should be responsible
for safety during operating hours and be familiar with OSHA regulations
and procedures.
9.5.4 Public Relations
As noted in Chapter 4 (Public Participation Program), sludge landfills
can be an emotional issue among the citizenry, especially those persons
living in the vicinity of the site. Good housekeeping practices, such as
control of odors (via prompt application of cover to sludge and spot
application of lime to sludge spills) as well as other efforts to protect
the environment, are important in gaining public acceptance.
Other public relation techniques that may be employed are periodic news
releases concerning the progress of the fill, citizen participation in
the completed site design, encouraging public visits to the site, and
establishing a mechanism for handling complaints from the public.
9.6 Cost Recordkeeping
A primary duty of sludge landfill management is to control costs. Ef-
fective cost control requires timely recognition of excessive costs and
the identification of the reason for such cost overruns. The increasing
costs and complexities of sludge landfill operations require the use of
more sophisticated cost control tools than have been used in the past.
Use of cost accounting systems at landfills are recommended in order for
management to control costs.
Because user fees are generally not charged at sludge landfills (reducing
the need for accountability) and sludge landfills are usually adminis-
tered by sewer departments and as such are not separate enterprises, but
merely a secondary facet of a larger operation, cost records at most
sludge landfills are either non-existent or poorly maintained.
The installation of a cost accounting system has several benefits, in-
cluding [4]:
The system facilitates orderly and efficient accumulation and
transmission of relevant data. Much of the recommended data is
already being collected or should be. Hence, the added cost of
installing the system is minimal.
9-13
-------
2. The data can be grouped in standard accounting classifications.
This simplifies interpretation of results and comparison with
data from previous years or other operations, and in turn, allows
analysis of relative performance and operational changes.
3. The system can account for all relevant costs of construction and
operation.
4. Accumulated data from the system can, over a period of time, lead
to standards of performance and efficiency that can be used to
control costs by indicating which costs are high and the reasons
for these costs. The supervisor of operations may then take
corrective action.
5. The system includes automatic provisions for accountability.
Cost control becomes more effective when the individual respon-
sible for cost increases can be ascertained.
6. Use of the collected data aids in short- and long-range fore-
casting of capital and operating budgets. Future requirements
for equipment, manpower, cash, etc., can be accurately estimated.
This, in turn, aids planning at all levels of management. The
data is also available for later evaluation and analysis.
7. The system can be flexible enough to meet the varying require-
ments of sludge landfills, of different sludge quantities and
types, site conditions, and landfill ing methods.
Generally landfill costs can be categorized into capital costs and
operating costs. For the purposes of the accounting system recommended
herein, capital costs are meant to include all non-recoverable initial
expenses required prior to the start-up of operation. Capital costs
usually include:
1. Land
2. Planning and design
3. Site preparation (i.e., clearing and grubbing, road construction,
surface water/1eachate controls, soil stockpiles, monitoring)
4. Facilities (i.e., offices, personnel shelters, garages, etc.)
5. Equipment purchase
Operating costs are expenses incurred during the on-going operation of
the landfill and usually include:
1. Equipment fuel
2. Equipment maintenance and parts
9-14
-------
3. Office/trailer rental
4. Supplies and materials
5. Utilities (i.e., electricity, heating oil, water, sewer, gas,
telephone, etc.)
6. Laboratory analyses
7. On-going inspection and engineering
Costs may be computed on the basis of wet tons, dry tons, and cubic
yards. Forms for compiling total and unit capital and operating costs
based on wet tons have been included as Figures 9-5 and 9-6.
FIGURE 9-5
CAPITAL COST FORM
(Area Fill Mound Receiving 500 wet tons/day)
Quantity
Unit Cost
Total Cost
Land
Site Preparation
Clearing and grubbing
Sodded diversion ditch
Sodded runoff ditch
Pond
Mom tori ng wel 1 s
Soil stockpiles
Garage (40 x 80)
Gravel Roads
Asphalt Roads
Miscellaneous
200 ac
100 ac
6,261 ft
6,261 ft
7
4
1,247,083 yd3
3,200 ft2
4,500 ft
750 ft
15T
2,500/ac
705/ac
2.50/LF
2.50/LF
7,500/ea
300/ea
2.55/yd3
15.00/ft2
1.85/LF
3.35/LF
1JT
500,000
70,500
15,652
15,652
52,500
1 ,200
,180,062
48,000
8,325
2,512
Equipment
Cat D-4 dozer
Cat D-6 dozer
Cat 941 track loader
Cat 955 track loader
Cat 930 wheel loader
Cat 621 scraper
Cat 930 backhoe
Subtotal
Engineering & 61,
TOTAL
Amortized @ 7% for 5 years
1 41,760
1 60,020
1 39,680
1 52,730
1 36,972
1 144,250
1 46,955
41 ,760
60,620
39,680
52,730
36,972
144,250
46,955
4,317,370
259,042
4,576,412
1,116,141
Total Annualized Cost
$1,116,141 t 182,500 tons = $6.12/wet ton
1 ton = 0.907 Mg
1 ac = 0.405 ha
9-15
-------
FIGURE 9-6
OPERATING COST FORM
(Area Fill Mound Receiving 500 wet tons/day)
quantity
(per year)
Unit Cost
Total Cost
TIT
Labor (10 men)
Equipment Fuel, Maintenance
4 Parts
1 - Cat D-4 dozer
1 - Cat D-6 dozer
t - Cat 941 track loader
1 - Cat 955 track loader
1 - Cat 930 wheel loader
1 - Cat 621 scraper
1 - Cat 930 backhoe
Office Trailer Rental
Utilities
Lab Analyses
Supplles 4 Materials
Engineering
Mi seellaneous
29,200 M-H
2,920 hrs
1,460 hrs
2,190 hrs
2,920 hrs
2,190 hrs
1,460 hrs
2,920 hrs
3 ea
3.00/hr
4.50/hr
8.37/hr
5.45/hr
8.98/hr
7.35/hr
21.88/hr
8.15/hr
3,720/ea
233,600
13,140
12,220
11 ,935
26,222
16,096
31 ,945
23,798
11 ,160
15,000
6,000
50,000
20,000
TOTAL
$471,116 t 182,500 tons = $2.58/wet ton
1 ton = 0.907 Mg
9.7 Financing
The management of a sludge landfill involves two
sions: (1) How should the capital requirements be
should the operating costs be financed? These
basic financial deci-
financed? and (2) How
decisions are influenced
largely by whether the landfill
Certain methods of financing are
general funds, general obligation
increases or special assessments
methods of financing are available
is a public or private operation.
available only to public operations:
borrowing, revenue bonds, sewer rate
, and grants and subsidies. Other
to both public and private operations:
loans and user
follows below.
fees. A description of each of these financing methods
9.7.1 General Funds
The general fund is derived from taxes. Although it normally cannot
provide enough money to meet capital costs, it is often used to pay for
9-16
-------
operating expenses [3], There are advantages to using the general fund
for this purpose. The administrative procedures and extra cost of
billing and collecting fees from contributing treatment plant authorities
are eliminated. Using general funds for sludge landfills does, however,
have disadvantages. Cost accounting and other administrative procedures
may be so relaxed that disposal costs may be difficult or impossible to
determine. It may also be extremely difficult for sludge landfill
operations to get money from the general fund because of the low priority
often assigned to them.
9.7.2 General Obligation Borrowing
General obligation borrowing is one method of financing the capital costs
of a sludge landfill. This type of bond generally carries a low interest
rate but is easily marketed because it is secured by the pledge of real
estate taxes and because all of the real estate within the taxing
district serves as security for the borrowed funds. State statutes
usually limit the amount of debt a community can incur. If the debt is
already substantial, this method may not be available. In some cases,
general obligation bonds are retired with revenues generated by the
sludge landfill; this minimizes the ad valorem taxes necessary for bond
retirement.
9.7.3 Revenue Bonds
Revenue bonds differ from general obligation bonds in that they are
secured only by the ability of the project to earn enough to pay the
interest and principals. In this case, fees must be charged to users of
the sludge landfill in amounts necessary to cover all capital and
operating expenses. Fees should be high enough to accumulate a surplus
over and above debt service needs in order to make the bonds attractive
to prospective purchasers. This method of financing requires that the
administering agency follow good cost accounting procedures, and it
allows the agency to be the sole beneficiary of cost saving procedures.
In addition, sewer authorities contributing sludge to the landfill are
forced to pay the true cost of its disposal.
9.7.4 Sewer Rate Increases or Special Assessments
When the sludge landfill is owned and operated by the sewer authority,
sewer rate increases or special assessments are the usual method of
financing both the capital and operating costs of the facility. If
strong opposition at a local level arises due to proposed increases in
sewer rates or special assessments, a public education program might be
in order to gain support for the additional charge.
9-17
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9.7.5 Grants or Subsidies
Sludge management systems may be eligible for various Federal, state, or
local funding. Sludge landfills are often eligible for grants from the
EPA Construction Grants Program administered by the Office of Water
Program Operations. These grants may cover a significant portion (up to
75%) of the capital fundings for the entire sludge management system
including land acquisition, equipment purchase, and site preparation [5].
In codisposal sites, or in sites that handle industrial sludges, the
amount of funding will be prorated based on what percentage of the total
waste processed at the site is municipal sludge. The funding received in
grants or subsidies is generally for the entire sludge management system,
including sludge processing systems at the treatment plant as well as
disposal systems. All of the operating costs and some of the capital
costs must be financed from other sources. Despite the large percentage
of the total cost which may remain after grants or subsidies have been
exhausted, this contribution may be essential in enabling local
governments to finance such systems as they become even more costly.
9.7.6 Loans
Loans from commercial institutions are often used to finance the capital
costs of constructing sludge landfills. Thereafter, user fees can be
used to accommodate operating costs and to gradually pay off the debt
incurred in construction. Accordingly, user fees should be set
sufficiently high to pay operating costs and to repay the loan. In
addition, a portion of user fees should be set aside to help finance
the ultimate use of the site and also capital construction of future
sludge landfill sites.
9.7.7 User Fees
When the sludge landfill is privately owned and operated, user fees are
the normal financing method. The private operation charges the contri-
buting sewer authority for disposing sludge. Alternatively, user fees
might be employed by a publicly owned and operated landfill if more than
one sewer authority contributes sludge. Sometimes, user fees are
employed when the landfill is publicly owned and receives sludge from
only one sewer authority. For example, a public works department
operating a sludge landfill may choose to finance its operation by
charging the sewer department for the sludge disposed.
User fees are primarily a source of operating revenue, but a municipality
might also employ them to generate funds for future capital
9-18
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expenditures such as preparing the final site and/or purchasing future
sites. However, it should be noted that fees do not usually provide the
capital outlay needed to start a sludge landfill.
Although fees necessitate a greater management expense due to the in-
creased recordkeeping required, these records provide a basis for cost
conscious management and operation of the landfill.
9.8 Typical Costs
This section presents typical costs for sludge hauling and landfilling.
Cost curves are presented in terms of cost per wet ton vs. sludge
quantity received. Typical costs are presented for (1) sludge hauling,
(2) annualized site capital costs, (3) site operating costs, and (4)
total site costs (combined annual ized capital and operating).
These curves can be useful in the early stages of sludge landfill
planning. However, typical costs should be used only in preliminary
work. Actual costs vary considerably with specific sludge and site
conditions. Therefore, use of these curves for computing specific
project costs is not recommended. Site-specific cost investigations
should be made in each case.
9.8.1 Hauling Costs
Typical costs for hauling wastewater treatment sludge are presented in
Figure 9-7. As shown, costs are given in dollars per wet ton as a
function of the wet tons of sludge delivered to the site each day. Costs
are presented for alternative distances of 5, 10, 20, 30, 40, and 50 mi
(8.0, 16.1, 32.2, 48.3, 64.4, and 80.4 km) hauls.
"Principals and Design Criteria for Sewage Sludge Application on Land"
[6] and "Transport of Sewage Sludge" [7] were the primary sources of
information for data and procedures in developing these hauling costs.
Other references [8][9][10] are available and were also consulted and
utilized. Sludge hauling costs were originally prepared for the year
1975 but were updated to reflect 1978 costs.
9-19
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FIGURE 9-7
TYPICAL HAULING COSTS
SOOOr
4000-
3000
S 1500 -
0 1000
^OMILE HAUL
!E HAUL
ILE HAUL
£ HAUL
to MIL"E HAUL
~E HAUL
SLUDGE QUANTITY RECEIVED
(WET TONS/OAY)
9-20
-------
The hauling costs shown in Figure 9-7 reflect not only transportation
costs, but also the cost of sludge loading and unloading facilities. For
a plant producing approximately 10 wet tons (9.1 Mg) per day of a de-
watered sludge and a 5-mi (8.0-km) haul, sludge loading and unloading
facilities were found to contribute 60% of the total hauling costs. For
a plant producing approximately 250 wet tons (227 Mg) per day of
dewatered sludge and a 40 mi (64.4 km) haul, loading and unloading
facilities contributed less than 10% of the total hauling costs.
Because of the differing bases for cost computations, certain assumptions
on sludge volumes and unit costs were utilized to produce the hauling
cost curve. These assumptions include:
1. The sludge was dewatered and had a solids content of
approximately 20%. It was hauled by a 15 yd3 (11.5 m3),
3-axle dump truck.
2. Hauling was performed 8 hrs per day, 7 days per week.
3. Fuel cost was $0.60 per gal ($0.16 per 1).
4. Labor (primarily truck driving) cost were $8.00 per hr including
fringe benefits.
5. Overhead and administrative costs were 25% of the operating
cost.
6. Capital costs were annual ized. A rate of 7% over 6 years was
used for the trucks with a salvage value of 15%. A rate of 7%
over 25 years was used for loading and unloading facilities with
no salvage value.
If conditions other than the above-stated conditions prevail at a given
site, the hauling costs in Figure 9-7 should be revised upward or
downward appropriately. As an example, if 10 yd3 (7.6 nr) 2-axle
dump trucks are used, costs should be higher by factors ranging from 1.3
for a plant generating 250 wet tons (227 Mg) per day with a 50-mi (80 km)
haul to 1.0 for a plant generating 10 wet tons (9.1 Mg) per day with a
5-mi (8.0 km) haul. Alternatively, if a 30 yd3 (23.9 m3) dump truck
is used, costs should be lower by factors ranging from 0.6 to 1.0 for the
aforementioned sludge quantities and haul distances.
9-21
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9.8.2 Site Costs
Typical site costs for landfill ing wastewater treatment sludges are
presented in Figure 9-8, 9-9, and 9-10. As shown, costs are given in
dollars per wet ton of sludge received as a function of the wet tons of
sludge delivered to the site each day. Costs are presented for each of
the alternative landfill ing methods. Scenarios using average design
dimensions and application rates were devised for the purposes of these
cos}: calculations. These scenarios are summarized in Table 9-1. The
cqst curve for each method was plotted from computations which assumed
alternative quantities of 10, 100, and 500 wet tons (9.1, 90.7, and 453
Mg) of sludge for each scenario.
Capital costs are summarized in Figure 9-8. Capital cost items
included:
1. Land
2. Site preparation (clearing and grubbing, surface water control
ditches and ponds, monitoring wells, soil stockpiles, roads, and
facil Hies)
3. Equipment purchase
4. Engineering
Capital costs were then annualized at 7% interest over 5 years (the life
of the site) and divided by the sludge quantity delivered to the site in
one year.
9-22
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FIGURE 9-8
TYPICAL SITE CAPITAL COSTS
FOR SLUDGE LANDFILLING
5000
4000
30.00
20.00
f? 1500
o>
a:
o
8
10.00
5.00
4.00
3.00
2.00
1.00
10
20
30
40 50
OO
SLUDGE QUANTITY RECEIVED
(WET TONS/DAY)
CODISPOSAL WITH
REFUSE
I
200
300 400 500
9-23
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FIGURE 9-9
TYPICAL SITE OPERATING COSTS
FOR SLUDGE LANDFILLING
50
100
200
300 400 500
SLUDGE QUANTITY RECEIVED
(WET TONS/DAY)
9-24
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FIGURE 9-10
TYPICAL TOTAL SITE COSTS FOR SLUDGE LANDFILLING
(COMBINED CAPITAL AND OPERATING COSTS)
o
u.
o 10.00
tu
•in-
1.00
zoo
300 400 500
SLUDGE QUANTITY RECEIVED
(WET TONS/DAY)
9-25
-------
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9-26
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Operating costs are summarized in Figure 9-9. Operating cost items
included:
1. Labor
2. Equipment fuel, maintenance and parts
3. Utilities
4. Laboratory analysis of water samples
5. Supplies and materials
6. Miscellaneous and other
Operating costs (see Figure 9-9) for one year were then divided by the
annual sludge quantity delivered to the site.
The costs shown, which were, derived from a variety of published informa-
tion sources [11][12][13] and case study investigations, have been
revised upward to reflect 1978 prices. Several assumptions were employed
in producing these cost curves. These assumptions include:
1. Life of the landfill site was 5 years
2. Land cost was $2,500 per acre ($6,177 per ha)
3. Actual fill areas (including inter-trench spaces) consumed 50%
of the total site area
4. Engineering was 6% of the total capital cost
5. Operating labor cost $8.00 per hour including fringe, overhead,
and administration
9-27
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It should be noted that the site costs shown for codisposal operations
were derived by dividing the additional annualized capital cost and
additional operating cost by the sludge quantity received. Actual unit
costs for typical refuse landfills not receiving sludge may be expected
to be less.
9.8.3 Cost Analysis
As stated previously, these cost curves should not be used for
site-specific cost compilations performed during design. However, they
can be useful in the preliminary planning stages of a specific sludge
landfill. In addition, they are useful in developing some general
conclusions about sludge landfill costs. For instance, cost ranges
included:
1. Hauling costs ranged from $8.80 per wet ton ($9.70 per Mg) for a
5-mi (8.1-km) haul of 500 wet tons (453 Mg) per day to $34.00
per wet ton ($37.49 per Mg) for a 50-mi (80.4-km) haul of 10 wet
tons (9.1 Mg) per day.
2. Annual ized site capital costs ranged from $2.20 per wet ton
($2.43 per Mg~)for a sTudge/ refuse codisposal operation
receiving 500 wet tons (453 Mg) per day to $10.10 per wet ton
($11.11 per Mg) for a diked containment operation receiving 10
wet tons (9.1 Mg) per day.
3. Site operating costs ranged from $1.20 per wet ton ($1.32 per
Mg]for a siudge/refuse codisposal operation receiving 500 wet
tons (453 Mg) per day to $36.10 per wet ton ($39.80 per Mg) for
an area fill mound operation receiving 10 wet tons (9.1 Mg) per
day.
4. Combined site costs ranged from $3.40 per wet ton ($3.75 per Mg)
for a sludge/refuse codisposal operation receiving 500 wet tons
(453 Mg) per day to $46.20 per wet ton ($50.94 per Mg) for an
area fill mound operation receiving 10 wet tons (9.1 Mg) per
day.
Also, an assessment can be made of the relative costs of alternative
landfilling methods. A prioritized list of landfilling methods is based
on total site costs (see Figure 9-10) with lowest costs first is as
fol1ows :
1. Codisposal with sludge/refuse mixture
2. Wide trench
3. Codisposal with siudge/soil mixture
9-28
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4. Narrow trench
5. Diked containment
6. Area fill layer
7. Area fill mound
The cost of a landfill ing method is determined by the efficiency of the
operation in terms of manpower, equipment, and land use. Other factors,
such as haul distances play a role in the cost effectiveness of a given
site but are the same for the various methods.
As indicated, codisposal and wide trench methods tend to be the most
economical landfill ing methods. Codisposal operations tend to be larger
and benefit from the economies of scale. In addition, the availability
of "free" bulking material in the form of refuse reduces labor costs.
Wide trenches have high application rates and are land and labor
efficient. It should be noted however, that the relatively high solids
content required for effective utilization of wide trenches will increase
the cost of sludge handling at the treatment plant.
Narrow trenches have relatively higher labor requirements and are land
intensive, contributing to high capital and operating costs. Area fill
mounds, and layers are labor and equipment intensive.
Diked containment requires a relatively large operation before it becomes
a cost-effective means of landfill ing. This is a result of high initial
labor and equipment requirements. Once established, however, diked con-
tainments are efficient in terms of operation and land use.
9.9 References
1. Sanitary Landfill, Manual of Practice No. 39. American Society of
Civil Engineers, Environmental Engineering Division, Management
Committee. 1976.
2. Refuse Handling Operations Safety Checklist, Technical Bulletin,
National Solid Waste Management Association, Vol. 4, No. 8, September
1973.
3. Brunner, D. R. and D. J. Keller. Sanitary Landfill Design and
Operation. U.S. Environmental Protection Agency. 1972.
4. Zavsner, E. R. An Accounting System for Solid Waste Collection.
U.S. Department of Health, Education, and Welfare, Public Health
Service; Bureau of Solid Waste Management. 1970.
5. R. Bastian. Municipal Sludge Management: EPA Construction Grants
Program. U.S. Environmental Protection Agency. 430/9-76-009. April
1976.
9-29
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6. Sommers, L. E., R. C. Fehrmann, H. L. Selznick, and C. E. Pound.
Principals and Design Criteria for Sewage Sludge Application on Land.
Sludge Treatment and Disposal Seminar Handout. U.S. Environmental
Protection Agency Technology Transfer. May 1978.
7. Clean Water Consultants, Inc. Transport of Sewage Sludge. U.S.
Environmental Protection AGency. Cincinnati, OH. Contract No.
68-03-2186. February 1976.
8. Pound, C. E., R. W. Crites, and D. A. Griffes. Costs of Wastewater
Treatment by Land Application. Technical Report. U.S. Environmental
Protection Agency. Washington, DC. EPA-430-9-75-003. June 1975.
9. Los Agneles/Orange County Metropolitan Area. Sludge Processing and
Disposal. A State-of-the-Art Review. Regional Wastewater Solids
Management Program. April 1977.
10. Spray Waste, Inc. The Agricultural Economics of Sludge
Fertilization. East Bay Municipal Utility District Soil Enrichment
Study. Davis, CA. 1974.
11. Equipment Guide Book Company. Green Guide, Volume I; The Handbook of
New and Used Construction Equipment Values. 1977.
12. Equipment Guide Book Company. Rental Rate Blue Book for Construction
Equipment. 1976.
13. Robert Snow Means Company, Inc. Building Construction Cost Data
1978. 1978.
9-30
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CHAPTER 10
DESIGN EXAMPLES
10.1 Introduction
The design of a sludge landfill is highly dependent upon many sludge
characteristics and site conditions, such as percent solids, climate,
soil, topography, and others. Consequently, no design example can be
universal. However, examples can be illustrative of the design and
operating procedures which have been recommended in the preceding
chapters.
This chapter contains three design examples. The approach in each of
these examples is to present sludge characteristics and site conditions
as given design data. The first example is for a large sludge landfill
receiving 19% solids sludge from a municipal wastewater treatment plant
serving a population equivalent of 200,000. In this example, the
landfill ing method is selected early in the design process, and the
design proceeds to (1) determine design dimensions, (2) prepare site
development plans, (3) determine equipment and personnel requirements,
(4) develop operational procedures, and (5) estimate costs. The second
example is for a sludge landfill receiving 29% solids sludge from a plant
serving a population equivalent of 50,000. In this example, two
alternative landfill ing methods appear to be equally suitable at first.
Alternate designs are performed for each before one method is selected on
the basis of costs. The third design example is for a small plant
serving a population equivalent of only 5,000. Plant management is faced
with a choice between landfill ing their 34% solids sludge at the
treatment plant site or disposing it at an existing refuse landfill.
It should be noted that the scope of this chapter is confined to design
only; i.e., it is assumed that the sites in the design examples have
already been selected. An example of the site selection process was
given in Chapter 4, Site Selection. It should also be noted that the
design described in this chapter is somewhat preliminary in nature. A
final designs should contain more detail and address other design
considerations (such as sediment and erosion controls, roads, leachate
controls, etc.) which are not fully addressed herein.
10.2 Design Example No. 1
10.2.1 Statement of Problem
The problem was to design a sludge-only landfill at the location of a
pre-selected site. As stated previously, the landfill was to receive
10-1
-------
a 19% solids sludge from an existing municipal wastewater treatment plant
serving a population equivalent of 200,000. The recommended design had
to be (1) in compliance with pertinent regulations, (2) environmentally
safe, and (3) cost-effective.
10.2.2 Design Data
The following information is included as given design data and was useful
in executing the subsequent design.
10.2.2.1 Treatment Plant Description
The wastewater treatment plant was a secondary treatment facility.
Further information on the facility is as follows:
1. Service population equivalent = 200,000
2. Average flow = 20 Mgal/d (0.86 nvVsec)
3. Industrial inflow = 10% of total inflow
4. Wastewater treatment processes:
a. bar screen separation
b. aerated grit tanks
c. primary settling tanks
d. secondary aeration tanks
e. secondary settling tanks
10.2.2.2 Sludge Description
Sludge was generated primarily by two sources (primary and secondary
settling tanks). The sludge was stabilized and dewatered. A more
complete description is as follows:
1. Sludge sources
a. primary settling tanks
b. secondary settling tnks
2. Sludge treatment
a. gravity thickening
b. mixing
c. anaerobic digestion
d. vacuum filtration
10-2
-------
3. Sludge characteristics (based on testing, review of records, and
calculations)
a. Solids content = 19%
b. Quantity on a dry weight basis = 13.0 dry tons/day
(11.8 Mg/day)
c. Quantity on a wet weight basis = 68.4 wet tons/day
(62.0 Mg/day)
d. Density = 1,700 Ibs/yd3 (1,009 kg/m3)
e. Quantity on a wet volume basis = 80.5 ydVday
(61.6 m3/day)
10.2.2.3 Climate
Significant cl imatological factors having an impact on sludge landfill ing
are listed below:
1. Precipitation = 32 in./yr (81 cm/yr)
2. Evaporation = 28 in./yr (71 cm/yr)
3. Number of days minimum temperature 32°F (0°C) and below
= 60 days/yr
As shown, the climate was relatively mild with cold temperatures
prevailing approximately two months per year. Precipitation exceeds
evaporation by 4 in./yr (10 cm/yr).
10.2.2.4 General Site Description
Preliminary data was collected during the site selection process. It is
summarized below:
1. Size of property = 375 acre (152 ha)
2. Property line frontage:
a. 5,200 ft (1,580 m) along county road
b. 4,700 ft (1,430 m) along residences
c. 4,600 ft (1,400 m) along grazing land
d. 1,200 ft (370 m) along woodland
10-3
-------
3. Slopes: Uniform slope of approximately 5%
4. Vegetation:
a. 225 acres (91 ha) of woodland
b. 150 acres (60 ha) of grassland
5. Surface water: None on site
A plan view of the site is presented in Figure 10-1. As shown, the site
had good access along a county road. The site was located in a
moderately developed residential area and abuts residences.
Approximately 60% of the site was covered with woodland. The balance of
the property had been used for grazing and remained grass-covered.
10.2.2.5 Hydrogeology
Eight test borings were performed on the site to determine subsurface
conditions. These were located as shown in Figure 10-1. Subsurface
conditions generally were similar at all boring locations and can be
summarized as follows:
Depth Description
0-12 ft (0-3.7 m) Silt loam
12-15 ft (3.7-4.6 m) Saturated silt loam
>15 ft (>4.6 m) Fractured crystalline rock
As can be seen above, groundwater was determined to be at a depth of 12
ft (3.7 m) and bedrock was at a depth of 15 ft (4.6 m). Samples of the
silt loam were collected for analysis and the following determinations
made:
1. Texture = medium
2. Permeability = 2 x 10~4 cm/sec
3. Permeability class = moderately slow
4. pH = 6.5
5. Cation exchange capacity (CEC) = 18 meq/100 g
10.2.3 Design
10.2.3.1 Landfill ing Method
Table 3-7 in Chapter 3 (Sludge Characteristics and Landfill ing Methods)
should be consulted as a reference. Since the sludge to be received is
10-4
-------
FIGURE 10-1
SITE BASE MAP FOR EXAMPLE NO. 1
250 500 760 1000
SCALE IN FEET
PASTURE
LEGEND
PROPERTY BOUNDARY
===== ROAD
8 DWELLING
-.f*$VV; WOODS
200 CONTOURS
BORING
10-5
-------
stabilized, it can be received by any of the five sludge-only landfill ing
methods shown in this table. Also, since the ground slope is relatively
flat at 5%, any of these five methods are suitable. However, since the
sludge has a solids content of 19%, only narrow trenches and area fill
layers are suitable operations. Lastly, since groundwater and bedrock
are relatively deep (at 12 and 15 ft (3.7 and 4.6 m), respectively), a
narrow trench operation should be employed. Because the solids content
of the sludge is between 15 and 20%, cover application should be via
land-based equipment as shown in Table 3-8. Soil should be used
primarily for cover and is not required for bulking.
10.2.3.2 Design Dimensions
Table 5-5 in Chapter 5 (Design) should be consulted as a reference. As
shown in this table, the design dimensions to be determined for any
trench operation include the following:
1. Excavation depth 5. Orientation
2. Spacing 6. Sludge fill depth
3. Width 7. Cover thickness
4. Length
The excavation depth is determined initially by the depth to groundwater
or bedrock. A minimum separation of 2 to 5 ft (0.6 to 1.5 m) is usually
provided between sludge deposits and the top of bedrock or groundwater.
In this case, a separation of 4 ft (1.2 m) was selected. The soil pH of
6.5 means a slightly higher than average opportunity for contaminant
movement since contaminants move somewhat more readily in an acidic soil.
However, the permeability was classified as "moderately slow" and the CEC
was relatively high at 18 meq/100 g. Thus, containment and attenuation
were seen as sufficient with a 4 ft (1.2 m) separation. Since
groundwater is at a depth of 12 ft (3.7 m) and is shallower than bedrock,
a 4 ft (1.2 m) separation dictates an excavation to 8 ft (2.4 m). Trench
spacing is determined chiefly by sidewall stability. As a general rule,
1.0 to 1.5 ft (0.30 to 0.46 m) of spacing provided for every 1 ft (0.3 m)
of trench depth. Since the soil type was found to be relatively stable,
1.0 ft (0.3 m) of spacing for every 1 ft (0.3 m) of trench depth
was suspected to be adequate and a total spacing of 8 ft (2.4 m) was
held.
Trench width is determined by sludge solids content and equipment con-
siderations. Since the sludge is only 19% solids, a 2 to 3 ft (0.6 to
0.9 m) width should be used.' Normally, when the sludge solids content is
less than 20%, cover applied atop the sludge would sink to the bottom.
However, at a width of 2 to 3 ft (0.6 to 0.9 m) the cover soil creates a
bridging effect over the sludge receiving its support from solid ground
on either side of the trench. A backhoe was selected as the most
10-6
-------
efficient piece of equipment for excavations to an 8 ft (2.4 m) depth.
Subsequently, a 2 ft (0.6 m) width was specified based on the equipment
efficiency of the backhoe. The length for narrow trenches is limited
only by the need to place containment within the trench to prevent
low-solids sludge from flowing to one end of a trench. Trench length was
set at 200 ft (61 m). Thus, at every 200 ft (61 m) the trench was
discontinued for 5 ft (1.5 m) to provide containment. With regard to
trench orientation, trenches should be kept parallel to one another to
optimize land utilization. Because of the relatively flat slopes at the
site, it was not found necessary to orient the trenches parallel to
topographic contours.
As shown in Table 5-5, for trench widths between 2 and 3 ft (0.6 and 0.9
m), the sludge fill depth should be to within 1 to 2 ft (0.3 to 0.6 m) of
the ground surface. Because the excavation depth is greater than usual
for a trench of this width, it was decided that sludge filling should
proceed no closer than 2 ft (0.6 m) from the top. Cover application for
a 2 ft (0.6 m) wide trench should be from 2 to 3 ft (0.6 to 0.9 m) thick.
This thickness was held at 3 ft (0.9 m) due to the large sludge fill
depth.
In order to test the practicality of these design dimensions, a
full-scale test was performed at the site. Initially, a backhoe was used
to excavate two parallel trenches at the previously-specified depth,
width, and spacing. A 10 yd3 (7.6 m3) dump truck (to be used in
sludge hauling) was then fully loaded with sludge and backed up to the
trench. Since the trench sidewall withstood the load, the prescribed
trench depth, width, and spacing were found to be sound. Subsequently,
the sludge load was dumped into the trench, filling it to a 6 ft (1.8 m)
depth. Three ft (0.9 m) of cover was then gently applied over the sludge
by the backhoe. The cover was found to be adequately supported at the
time. At an inspection of the test trenches several weeks later no
sludge had emerged. However, the cover had settled almost 1 ft (0.3 m).
Since this settlement could cause ponding of rainwater over settled
trenches in the future, the cover application thickness was increased to
a total of 4 ft (1.2 m) or to 2 ft (0.6 m) above grade. The design was
then able to proceed based on the following design dimensions:
1. Excavation depth = 8 ft (2.4 m)
2. Spacing = 8 ft (2.4 m)
3. Width = 2 ft (0.6 m)
4. Length = 200 ft (61 m)
5. Orientation = trenches parallel to each other but not
necessarily parallel to contours
6. Sludge fill depth = 6 ft (1.8 m)
7. Cover thickness = 4 ft (1.2 m)
10-7
-------
10.2.3.3 Site Development
Site development was in accordance with the plan shown in Figure 10-2.
Features of this plan included the following:
1. A 300 ft (91 m) wooded buffer was maintained between the sludge
fill area and residences. A 200 ft (61 m) buffer was maintained
around the balance of the property.
2. Trenches were installed along the downhill (southeastern)
property line to collect storm water runoff. A sedimentation
pond was constructed to receive runoff collected by these
trenches
3. In accordance with State regulations and engineering judgement,
one groundwater monitoring well was located upgradient from the
fill area and three monitoring wells were located down-gradient
from the fill area.
4. The site was divided into nine fill areas so that the site could
be cleared in phases. In this way, clearing could proceed
approximately once each year in advance of sludge filling
operations.
5. The fill area located nearest to the site entrance was
designated for wet weather operations. The access road to this
area was paved with asphalt.
6. The remaining access roads were covered with gravel.
7. After providing area for buffers, access roads, facilities, etc.
approximately 156 acres (63 ha) remained as usable fill area out
of the entire 375 acres (152 ha) on the site.
10.2.3.4 Calculations
Based on the design data and dimensions stated previously, calculations
can then be made of the (1) trench utilization rate, (2) sludge
application rate, (3) land utilization rate, and (4) site life.
10-8
-------
FIGURE 10-2
SITE DEVELOPMENT PLAN FOR EXAMPLE NO. 1
PASTURE
CHECK STATION
PASTURE
PASTURE
LEGEND
— PROPERTY BOUNDARY
= ROAD
DWELLING
WOODS
• ASPHALT PAVED ACCESS ROAD
GRAVEL ACCESS ROAD
) SEDIMENTATION POND
MONITORING WELL
© SLUDGE FILL AREA
10-9
-------
. -, , , , . . sludge volume per day
1. Trench utilization rate • a ; r—-—=*—.—
cross-sectional area of sludge
in trench
_ sludge volume per day
Ttrench fill depth)x(trench widthT"
_ (60.5 yd3/day)x(27 ft3/yd3)
(6 ft) x (2 ft)
181 ft/day (55.2 m/day)
2. Sludge application rate = cross-sectional area of sludge in trench
width of trench + spacing
(6 ft)x(2 ft) 12 ft2 _ 12 ft3
= (2 ft)+f8~Tt7 10 ft " TOTE?
= (12 ft3)(l yd3/27 ft3)
(10 ft2)(l acre/43,560 ft2)
= 1,936 yd3/acre (3,659 m3/ha)
. . ., . . . sludge volume per
3. Land utilization rate - . , ' fTprat —
80.5 yd3/day
1,936 yd3/acre
= 0.0416 acres/day (0.0168 ha/day)
4. Site life = usable fl11 area
land utilization rate
156 acres = 3,750 days
0.0416 acres/day 365 days/year
= 10.3 years
10.2.3.5 Equipment and Personnel
Table 6-4 in Chapter 6 (Operation) should be consulted as a reference.
As shown, for a narrow trench operation receiving between 50 and 100 wet
tons per day (45 and 91 Mg per day) the following equipment might be
selected:
Description Quantity Hours per Week
Track backhoe with loader 1 49
Track dozer 1 !i
Total 2 64
10-10
-------
The use of a backhoe was already established during the selection of
design dimensions. Therefore, the above suggested scheme was
implemented. The duties and number of personnel were also established at
this stage and included:
Description Quantity Hours per Week
Backhoe operator 1 40
Backhoe and dozer operator 1 40_
Total 2 80
Operations are conducted at the site 8 hours per day and seven days per
week to coincide with sludge deliveries and avoid the added cost and
odors often encountered with sludge storage facilities. The backhoe is
operated seven hours per day (plus one hour downtime per day for routine
maintenance and cleanup) and seven days per week. The dozer is operated
three hours per day (plus one hour downtime per day for routine
maintenance and cleanup) and five days per week. One full-time operator
works 8 hours per day Monday through Friday. He is responsible for
operating and maintaining the backhoe during these hours. The other
operator works 8 hours per day Wednesday through Sunday; he is
responsible for (1) operating and maintaining the backhoe for eight hours
each day on Saturday and Sunday, (2) operating and maintaining the dozer
for four hours each day on Monday through Friday, and (3) performing
miscellaneous functions such as check station attendant, compiling site
records, etc.
10.2.3.6 Operational Procedures
Site preparation consisted of the following procedures:
1. Initially, fill area no. 1 and the inclement weather area were
cleared and grubbed. Roads providing access to these areas were
paved with asphalt or gravel (as shown in Figure 10-2). Several
trenches were excavated in the inclement weather area and the
spoil stockpiled alongside each trench. Runoff, erosion, and
sedimentation controls as well as monitoring wells were
installed.
2. At least one month (but never more than four months) in advance
of the fill operation, each new fill area is cleared and
grubbed. Usually these operations occur once each year and are
timed to avoid cold temperatures and frozen ground conditions.
The work is performed by equipment and personnel brought in
specifically for this task. Debris is disposed of on-site by
burial and/or by producing wood chips.
10-11
-------
On-going operations consist of the following:
1. Trenching begins in the corner of each fill area furthest
removed from the access road and proceeds generally toward the
road as it is completed.
2. Approximately 200 ft (61 m) of trench length is prepared in
advance of the filling operation. This provides contingency
capacity for slightly more than one day's sludge receipt.
3. Trenches are excavated to design dimensions by the track backhoe
as it straddles the excavation (see Figure 10-3).
FIGURE 10-3
OPERATIONAL PROCEDURES FOR EXAMPLE NO. 1
SLUDGE
COVER SOIL
10-12
-------
Haul vehicles back-up to the previously excavated trench and
dump sludge loads directly into the trench. Filling proceeds to
approximately 2 ft (0.6 m) below the top of the trench. Because
of its low solids content, sludge flows evenly throughout the
trench and accumulations at one location are minimized.
Within one hour after siudge-filling has occurred in one
location, the track backhoe excavates a new trench adjacent to
the filled trench. Excavated material from the new trench is
applied as cover over the adjacent sludge-filled trench. The
cover is applied carefully from a low height at first to
minimize the amount of cover sinking into sludge deposits.
Subsequently, cover is applied less carefully. Ultimately the
cover extends to 2 ft (0.6 m) above grade.
Site completion consists of the following procedures:
1. Approximately one-month after completion of each 1-acre (0.405
ha) portion of the landfill, the bulldozer is used to regrade
the area to a smooth ground surface.
2. Immediately thereafter the site is hydroseeded (assuming weather
conditions permit) and grasses soon take root.
10.2.3.7 Cost Estimates
Based on the site design, cost estimates were prepared for capital and
operating costs in Tables 10-1 and 10-2, respectively. As shown, the
total capital cost of the site was estimated at $1,186,421. If this cost
is amortized at 7% interest over 10 years (the approximate life of the
site), the annual cost is $168,923. Considering a site capacity of
260,000 wet tons (236,000 Mg) of sludge, the capital cost is $0.65 per
wet ton ($0.72 per Mg).
As shown in Table 10-2, the annual operating cost was estimated at
$89,413. Considering an annual receipt of 25,000 wet tons (22,700 Mg) of
sludge, the unit operating cost is $3.58 per wet ton ($3.95 per Mg).
Combined capital and operating costs were estimated at $4.23 per wet ton
($4.67 per Mg).
10-13
-------
TABLE 10-1
ESTIMATE OF TOTAL SITE CAPITAL COSTS FOR EXAMPLE NO. 1
I tern
_ Quantity
375 acres
Unit Cost
Land 375 acres $ 2.500/acre
Site Preparation
Clearing and Grubbing 45 acres $ 705/acre
Sodded Runoff Ditch 4000 ft $ 2.50/acre
Pond 1 ea $15,000/ea
Monitoring Wells 4 ea $ 300/ea
Garage 1600 ft* $ 15/ft/
Gravel Roads 1500 ft $ 1.85/ft
Asphalt Roads 1000 ft $ 3.35/ft
Miscellaneous — —
Total Cost _
$ 937,500
31,725
10,000
15,000
1,200
24,000
2,775
3,350
5,000
Equipment
Backhoe
Dozer
Subtotal
Engineering @ 6%
1 ea $46,955
1 ea $41,760
— —
$
$
$
$
46,955
41,760
1,119,265
67,156
Total
$ 1,186,241
1 acre = 0.405 ha
1 ft = 0.305 m
TABLE 10-2
ESTIMATE OF ANNUAL OPERATING COSTS FOR EXAMPLE NO. 1
Item
Quantity
Unit Cost
Total Cost
Labor
Backhoe Operator
Backhoe/Dozer Operator
Equipment Fuel, Maintenance
and Parts
2,080 hrs
2,080 hrs
$ 8.00/hr
$ 8.00/hr
$16,640
$16,640
Backhoe
Dozer
Clearing and Grubbing
Gravel Roads
Officer Trailer Rental
Utilities
Laboratory Analyses
Supplies and Materials
Miscellaneous
2,555 hrs
780 hrs
10 acres
1,500 ft
1 ea
--
--
--
~~
$ 6.88/hr
$ 4.50/hr
$ 705/acre
$ 1.85/ft
$3,720/ea
--
--
—
~~
$17,578
$ 3,510
$ 7,050
$ 2,775
$ 3,720
$ 2,000
$ 2,500
$12,000
$ 5,000
Total
$89,413
1 acre = 0.405 ha
1 ft = 0.305 m
10-14
-------
10.3 Design Example No. 2
10.3.1 Statement of Problem
The problem was to design a sludge-only landfill at the location of a
pre-selected site. As stated previously, the landfill was to receive a
29% solids sludge from a proposed municipal wastewater treatment plant
serving a population equivalent of 50,000. The recommended design had to
be (1) in compliance with pertinent regulations, (2) environmentally
safe, and (3) cost-effective.
10.3.2 Design Data
The following information is included as given design data and was useful
in executing the subsequent design.
10.3.2.1 Treatment Plant Description
The proposed municipal wastewater treatment plant was to be a modern
secondary treatment facility. Further information on the facility is as
follows:
1. Service population equivalent = 50,000
2. Average flow = 5.0 Mgal/d (0.22 nwsec)
3. Industrial inflow = 0% of total inflow
4. Wastewater treatment processes:
a. bar screen separation
b. primary clarifier
c. secondary clarifier
d. sand filters
e. chlorine contact tanks
10.3.2.2 Sludge Description
Sludge was to be generated primarily from two sources (primary and
secondary clarifiers). The sludge was to be anaerobically digested and
dewatered. A more complete description is as follows:
10-15
-------
1. SI udge sources:
a. primary clarifiers
b. secondary clarifiers
2. Sludge treatment:
a. gravity thickening
b. mixing
c. anaerobic digestion
d. dewatering via belt presses
3. Sludge characteristics (based on treatment plant design report)
a. solids content = 29%
b. quantity on a dry weight basis = 3.25 dry tons/day
(2.95 Mg/day)
c. quantity on a wet weight basis = 11.2 wet tons/day
(10.2 Mg/day)
d. density = 1,750 lbs/yd3 (1,039 kg/m3)
e. quantity on a wet volume basis
(11.2 tons/day)x(2,OQO Ibs/ton)
(1,700 lbs/yd3)
= 13.2 yd3/day (10.1 m3/day)
10.3.2.3 Climate
Significant climatological factors having an impact on sludge landfill ing
are listed below:
1. Precipitation = 48 in./yr (122 cm/yr)
2. Evaporation = 30 in./yr (76 cm/yr)
3. Number of days minimum temperature 32°F (0°C) and below
= 125 days/yr
As shown, the climate is quite cold with freezing temperatures prevailing
much of the year. Precipitation is high and evaporation exceeds
precipitation by 18 in./yr (46 cm/yr).
10-16
-------
10.3.2.4 General Site Description
Site data was collected from existing information sources as well as
field investigations performed during the site selection process. This
data is summarized below:
1. Size of property = 12 acres
2. Property line frontage:
a. 1,750 ft (533 m) along woodland
b. 500 ft (152 m) along crop land
c. 850 ft (259 m) along a county road with woodland on the
other side
3. Slopes = relatively flat with slopes at approximately 2%
4. Vegetation:
a. 6.5 acres (2.6 ha) of woodland
b. 5.5 acres (2.2 ha) of open space sparsely covered with
grasses
5. Surface water = none on site; drainage on site via overland
sheet flow into roadside ditch
A plan view of the site is presented in Figure 10-4. As shown, the site
has good access from a two-lane county road adjoining the property.
Approximately, one-half of the site is wooded; the balance is open space
with some grasses. Cropland adjoins the property to the east. Other
adjoining properties are undeveloped and wooded.
10.3.2.5 Hydrogeology
During the site selection phase, soil maps for the area were reviewed.
In addition, logs of soil borings and wells drilled near the site were
examined. Historical records compiled on nearby drinking water wells
were reviewed for groundwater levels and seasonal fluctuations.
Subsequent to the site selection, four soil borings were performed at the
site to verify subsurface conditions. These borings are located as shown
in Figure 10-4. Subsurface conditions were found to be somewhat
consistent at all boring locations and can be summarized as follows:
10-17
-------
FIGURE 10-4
SITE BASE MAP FOR EXAMPLE NO. 2
100 200
SCALE IN FEET
300
LEGEND
- PROPERTY BOUNDARY
= COUNTY ROAD
CROP LAND
£&<£#; WOODS
200 CONTOURS
S BORING
10-18
-------
Depth Description
0-10 ft (0-3.0 m) Coarse sand with silty sand
>10 ft (>3.0 m) Saturated coarse sand
As shown above, the soil was primarily a coarse sand; however, the sand
had some layers of silty sand interspersed throughout. Groundwater was
at a 10 ft (3.0 m) depth. Due to the site's location on the coastal
plain, bedrock is deep. Samples of the coarse sand were collected for
analysis and the following determinations were made.
1. Texture = coarse
2. Permeability = 8 x 10~4 cm/sec
3. Permeability class = moderately rapid
4. pH = 6.0
5. Cation exchange capacity (CEC) = 8 meq/100 g
10.3.3 Design
10.3.3.1 Landfill ing Method
Table 3-7 in Chapter 3 (Sludge Characteristics and Landfill ing Methods)
should be consulted as a reference. Since the sludge is stabilized and
has a solids content of 29%, this sludge can be disposed in any of the
five sludge-only methods shown. Also, none of these five methods are
disqualified on the basis of slopes, since the site is relatively flat
(2% slopes).
Because the site was relatively small and a longer site life was desired,
it was obvious early in the design process that a high sludge application
rate was required. As shown in Table 3-8, the highest sludge application
rates are attained with wide trenches, area fill mounds, and diked
containments. Diked containment was ruled out because the high applica-
tion rates sometimes achieved with this method are only possible for
large diked containments (with high dikes) receiving large quantities of
sludge. Wide trenches were intially selected based on the cost- effec-
tiveness of this operation versus area fill mounds. However, subsurface
application of sludge at this site was marginal. Normally, a 10 ft (3.0
m) depth to groundwater would be sufficient to allow excavation and still
provide sufficient buffer soils. However, the soil's coarse texture,
moderately rapid permeability, low pH, and low CEC all indicated a strong
potential for contaminant movement with insufficient attenuation. Al-
though minimum soil bufgfers of 2 to 5 ft (0.6 to 1.5 m) are adequate in
many cases, the State mandated an 8 ft (2.4 m) soil buffer between sludge
deposits and groundwater. Therefore, it became apparent that surface
landfilling of sludge in area fill mounds might be the only alternative.
10-19
-------
However, area fill mounds have disadvantages in high precipitation areas
such as at this site. Therefore, subsurface placement of sludge in lined
wide trenches was introduced into consideration.
10.3.3.2 Design Dimensions
Preliminary designs were performed for each of the landfill ing methods
still under consideration. The purpose of these designs was to provide a
basis for the site life and cost for each method. Subsequently, a
selection of - the method could be made using the life and cost of each.
Using Tables 5-5 and 5-7 in Chapter 5 (Design), design dimensions were
computed for each method as shown in Table 10-3.
TABLE 10-3
DESIGN CONSIDERATIONS FOR EXAMPLE NO. 2
Design Consideration
Wide Trench
Area Fill Mound
Width
Depth
Length
Spacing
Bulking performed
Bulking agent
Bulking ratio
Sludge depth per lift
No. of lifts
Cover applied
Location of equipment
Interim cover thickness
Final cover thickness
Imported soil required
50 ft
8 ft
200 ft
20 ft
no
--
—
4 ft
1
yes
sludqe-based
--
4 ft
no
„
--
--
--
yes
soil
1 soil: 1 sludge
6 ft
1
yes
sludge-based
--
3 ft
yes
1 ft = 0.305 m
10.3.3.3 Site Development
Site development was planned in accordance with Figures 10-5 and 10-6 for
wide trench and area fill mound operations, respectively. Features
included in both plans are as follows:
A buffer was maintained to all adjoining property. Where wooded
areas existed along property frontages, a 100 ft (30 m) wide
strip was maintained in its natural state. Where grassy open
space areas existed along property frontages, a 150 ft (46 m)
wide strip was undisturbed.
A sodded diversion ditch was included along the uphill side of
the site to intercept upland drainage. Intercepted runoff was
directed to existing roadside ditches.
10-20
-------
FIGURE 10-5
SITE DEVELOPMENT PLAN FOR EXAMPLE NO. 2 WIDE TRENCH
100 200
1 F"
SCALE IN FEET
300
CROP LAND
LEGEND
-PROPERTY BOUNDARY
COUNTY ROAD
'WOODS
ASPHALT PAVEMENT
MOUND AREA
• DIVERSION DITCH
COLLECTION DITCH
SEDIMENTATION POND
10-21
-------
FIGURE 10-6
SITE DEVELOPMENT PLAN FOR EXAMPLE NO. 2 AREA FILL MOUND
100 ZOO
H—
SCALE IN FEET
300
CROP LAND
CROP LAND
LEGEND
---- PROPERTY BOUNDARY
...... COUNTY ROAD
WOODS
---- GRAVEL ROAD
TRENCH
DIVERSION DITCH
COLLECTION DITCH
SEDIMENTATION POND
10-22
-------
3. A sodded collection ditch was included along the downhill side
of the site to intercept on-site drainage. Intercepted runoff
was directed to a new sedimentation pond.
Features specific to the wide trench operation shown in Figure 10-4
included the following:
1. Trenches were laid out in accordance with design dimensions and
made optimal use of available land.
2. Gravel roads were constructed as shown to provide access from
the site entrance to individual trenches.
3. Sheets of 20 mil (0.05 cm) Hypalon were selected for application
to the floor and sidewalls (2:1 slope) of all trenches.
Features specific to the area fill mound operation shown in Figure 10-5
included the following:
1. An asphalt-paved dumping/mixing pad and access road were
specified.
2. A soil stockpile area was located near the dumping/mixing pad.
Soil for this stockpile was imported once each year from another
location incurring a 3-mile haul.
3. Most of the remaining site area was designated for sludge
mounding operations.
10.3.3.4 Calculations
Based on the design data and dimensions stated previously, calculations
were performed for each of the proposed landfill ing methods.
Determinations made on the wide trench application include:
1. Trench capacity = 1,481 yd3/trench (1,132 m3/trench)
2. Number of trenches = 12
3. Site capacity = 17,772 yd3 (13,588 m3)
4. Sludge volume received = 13.2 yd3/day (10.1 m3/day)
5. Site life = 3.7 years
10-23
-------
Determinations made on the area fill mound application include:
1. Sludge application rate = 9,680 yd3/acre (18,295 m3/ha)
2. Size of mounding area = 3 acres (1.22 ha)
3. Site capacity = 29,040 yd3 (22,204 m3)
4. Sludge volume received = 13.2 yd3/day (10.1 nr/day)
5. Site life = 6.0 years
10.3.3.5 Equipment and Personnel
Using Table 6-4 in Chapter 6 (Operation) as a reference, the following
equipment and personnel were selected for use at the wide trench
operation:
Description Quantity Hours per Week
Track dozer 1 10
Track dozer operator 1 15
The following equipment and personnel were selected for use at the area
fill mound operation:
Description Quantity Hours per Week
Track loader 1 15
Track loader operator 1 20
10.3.3.6 Cost Estimates
Cost estimates were computed for each of the proposed landfill ing
methods. These estimates have been included as Tables 10-4 through
'10-7. As shown, the annual operating cost of the wide trench operations
was calculated at $30,195. The total capital cost was calculated at
$95,552. This amount was amortized at 7% interest over 4 years (the
approximate life of the wide trench operation). The amortized capital
cost derived was $28,209.
The annual operating cost of the area fill mound operation was calculated
at $44,624. The total capital cost was calculated at $107,325. This
amount was amortized over 6 years (the life of the area fill mound
operation). The amortized capital cost derived was $22,517.
10-24
-------
TABLE 10-4-
ESTIMATE OF TOTAL SITE CAPITAL COSTS FOR EXAMPLE NO. 2
WIDE TRENCH
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Monitoring Wells
Gravel Roads
Miscellaneous
Equipment
Track Dozer
Subtotal
Engineering @ 6%
Total
1 acre = 0.405 ha
1 ft = 0.305 m
Quantity
12
6
1,750
850
1
3
950
1
acres
acres
ft
acres
ea
ea
ft
--
ea
„
--
--
Unit Cost
$ 2
$
$
$
$ 3
$
$
$41
,500/acre
705/acre
2.50/ft
2.50/ft
,000/ea
300/ea
1.85/ft
--
,760/ea
__
--
--
Total Cost
$30.000
$ 4.230
$ 4,375
$ 2,125
$ 3,000
$ 900
$ 1,757
$ 2,000
$41,760
$90,147
$ 5,405
$95,552
TABLE 10-5
ESTIMATE OF ANNUAL SITE OPERATING COSTS FOR EXAMPLE NO. 2
WIDE TRENCH
Item
Labor
Dozer Operator
Equipment Fuel, Maintenance
and Parts
Track Dozer
Hypalon Liner (installed)
Laboratory Analysis
Other Supplies and Materials
Mi seel laneous
Total
Quantity
780 hrs
520 hrs
2,700 ft2
--
Unit Cost
$8.00/hr
$4.50/hr
$0.45/ft2
--
Total Cost
$ 6,240
$ 2,340
$ 1,215
$ 2,500
$ 5,000
$ 2,000
$30,195
1 ft2 = 0.093 m?
10-25
-------
TABLE 10-6
ESTIMATE OF TOTAL SITE CAPITAL COSTS FOR EXAMPLE NO. 2
AREA FILL MOUND
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Monitoring Wells
Asphalt Paving
Miscellaneous
Equipment
Track Loader
Subtotal
Engineering 1? 6?
Total
Quantity
12
6
1,750
850
1
3
4,200
1
-
-
acres
acres
ft
ft
ea
ea
ft2
ea
-
-
Unit Cost
$ 2
$
$
$
$ 3
$
$ 0
$52
,500/acre
705/acre
2.50/ft
2.50/ft
,000/ea
300 /ea
.45/ft2
,730/ea
--
-
Total
$ 30,
$ 4,
$ 4,
$ 2,
$ 3,
$
$ 1,
$ 2,
$ 52,
$101,
$ 6,
$107,
Cost
000
230
375
125
000
900
890
000
730
250
075
325
1 acre = 0.405 ha
1 ft = 0.305 m
1 ft2 = 0.093 m2
TABLE 10-7
ESTIMATE OF ANNUAL SITE OPERATING COSTS FOR EXAMPLE NO. 2
AREA FILL MOUND
Item
Quantity
Unit Cost
Total Cost
Labor
Loader Operators
Equipment Fuel, Maintenance,
and Parts
Track Loader
Laboratory Analysis
Supplies and Materials
Miscellaneous
Total
1,040 hrs
780 hrs
$ 8.00/hr
$ 8.98/hr
$ 8,320
$ 7,004
$ 2,500
$ 5,000
$ 2,000
$24,824
10-26
-------
Unit costs for each operation were compiled and are summarized below:
Wide trench
Area fill mound
Amortized
Capital Cost
$6.90/wet ton
($7.61/Mg)
$5.51/wet ton
($6.07/Mg)
Operating
Cost
$7.39/wet ton
($8.15/Mg)
$9.26/wet ton
($10.21/Mg)
Total
Cost
$14.29/wet ton
($15.76/Mg)
$14.77/wet ton
($16.28/Mg)
10.3.3.7 Conclusion
An area fill mound operation was subsequently selected and utilized.
Although the mound operation actually cost more than the wide trench, the
cost difference was not that substantial and the mounding operations
longer life made it the clear-cut choice.
10.4 Design Example No. 3
10.4.1 Statement of Problem
The problem was to design a sludge-only landfill on the site of a
wastewater treatment plant serving a population equivalent of 5,000. The
plant had been disposing of their 34% solids sludge at a refuse landfill
8 miles (13 km) distant. However, landfill operators were now charging
$8.00 per wet ton ($8.82 per Mg) for the sludge; treatment plant
operators sought the cost-savings that might be realized by landfill ing
the sludge themselves. The recommended design had to be (1) in
compliance with pertinent regulations, (2) environmentally safe, and (3)
cost-effective.
10.4.2 Design Data
The following information is included as given design data and was useful
in executing the subsequent design.
10.4.2.1 Treatment Plant Description
Ther existing wastewater treatment facility was a package plant. Further
information on the facility is as follows:
10-27
-------
1. Service population equivalent = 5,000
2. Average flow = 0.5 Mgal/d (0.022 rrvVsec)
3. Industrial inflow = 0% of total inflow
4. Wastewater treatment processes:
a. bar screen separation
b. primary clarifier
c. aeration tanks
d. secondary clarifier
10.4.2.2 Sludge Description
Sludge from the secondary clarifier was recirculated to the primary
clarifier. The sludge was stabilized and dewatered. A more complete
description is as follows:
1. Sludge sources - sludge from secondary clarifier recirculated to
primary clarifier and withdrawn as mixture with primary sludge
2. Sludge treatment:
a. aerobic digestion
b. dewatering via sand drying beds
3. Sludge characteristics (based on testing, review of records, and
calculations)
a. solids content = 34%
b. quantity on a dry weight basis = 0.33 dry tons/day
(0.30 Mg/day)
c. quantity on a wet weight basis = 0.96 wet tons/day
(0.87 Mg/day)
d. density = 1,850 lbs/yd3 (1,098 kg/m3)
e. quantity on a wet volume basis = 1.03 yd^/day
(0.79 m3/day)
10.4.2.3 Climate
Significant climatological factors having an impact on sludge landfill ing
are listed below:
10-28
-------
1. Precipitation = 32 in./yr (81.3 cm/yr)
2. Evaporation = 34 in./yr (86.4 cm/yr)
3. Number of days minimum temperature 32°F (0°C) and below
= 40 days/yr
As shown the climate is marked by mild temperatures. Precipitation and
moderate and is exceeded slightly by evaporation.
10.4.2.4 General Site Description
The area to be used for sludge landfill ing occupied a 3-acre (1.2 ha)
portion of the 8-acre (3.2 ha) treatment plant property. It was located
immediately adjacent to the plant's sand drying beds. Other data
concerning this 3-acre tract is summarized below:
1. Adjoining properties and facilities:
a. 700 ft (210 m) abuts woodland which is privately owned
b. 700 ft (210 m) abuts treatment plant facilities
2. Slopes = evenly sloped at about 6%
3. Vegetation = all 3 acres (1.2 ha) had been previously cleared
and are covered with grasses
4. Surface water = none of the 3-acre (1.2 ha) tract. A stream
which receives effluent from the treatment is located 500 ft
(150 m) away.
10.4.2.5 Hydrogeology
Site hydrogeological data was collected largely from information
contained in the treatment plant report and drawings. Some additional
information on soils, bedrock, and groundwater was obtained from the
sources listed in Table 5-3 of Chapter 5 (Design).
Subsurface conditions are summarized as follows:
Depth Description
0-10 ft (0.3.0 m) Silty clay with some clay lenses
interspersed throughout
10-12 ft (3.0-3.7 m) Saturated silty clay
12-15 ft (3.7-4.6 m) Clay
15-26 ft (4.6-7.9 m) Saturated silty clay
>26 ft (7.9 m) Bedrock
10-29
-------
As shown, the upper 10 ft (3.0 m) of soil was a dry silty clay; ground-
water was encountered at a 10 ft (3.0 m) depth. A 3 ft (0.9 m) thick
tight clay seam protects the groundwater located below it. Using Tables
4-1 and 4-2 and Figure 4-4 and 4-5 from Chapter 4 (Site Selection), the
following determinations were made:
1. Texture = fine
2. Permeability = approximately 10"^ cm/sec
3. Permeability class = very slow
4. Cation exchange capacity (CEC) = over 20 meq/100 g
10.4.3 Design
10.4.3.1 Landfill ing Method
Table 3-7 should be consulted as a reference. This site was conducive to
subsurface placement of sludge since (1) groundwater and bedrock are
relatively deep (at 10 and 26 ft (3.0 and 7.9 m), respectively) and (2)
the soils are tight enough to afford sufficient environmental protection
even when sludge is placed relatively close to the groundwater. Since
area fills are generally more manpower and equipment-intensive then
trenches, trenches should be selected in almost all instances where
hydrogeologic conditions allow. In addition, wide trenches should be
selected over narrow trenches for sludge with a solids content of 34% as
shown in Table 3-8. Cover application should be via sludge-based
equipment. All of these considerations were established and utilized in
the preliminary design.
10.4.3.2 Design Dimensions
Using Table 5-5, the .following design dimensions were established:
1. Width = 20 ft (6.1 m)
2. Depth = 8 ft (2.4 m)
3. Length = 100 ft (30 m)
4. Spacing = 30 ft (9.1 m)
5. Sludge fill depth = 5 ft (1.5 m)
6. Cover thickness = 4 ft (1.2 m)
Test trenches were then constructed on the site and operated under pro-
posed conditions to ensure their effectiveness and practicality in a
full-scale operation. The test was successful and the design proceeded
based on the above dimensions.
10-30
-------
10.4.3.3 Calculations
Based on the design data and dimensions stated previously, calculations
were performed for each of the proposed landfill ing methods. Determina-
tions made on the operation included:
1. Trench capacity = 375 yd3 (287 m3)
2. Number of trenches =20
3. Site capacity = 7,500 ydj (5,734 nr)
4. Sludge volume received = 1.03 yd3/day (0.79 m3/day)
5. Site life = 20 years
10.4.3.4 Operational Procedures
Site preparation, on-going operations, and site completion consist of the
following procedures:
1. Twice each year a contractor is employed to excavate sufficient
trench capacity for a 6 month sludge quantity. The contractor
uses a single front-end loader to excavate each 20 ft (6.1 m)
wide trench to a depth of 8 ft (2.4 m). Excavated soil is
stockpiled above and along both sides of the trench.
2. Immediately after the trench is excavated, 6 months accumula-
tion of sludge is removed from sand drying beds with pitchforks
and loaded on a dump truck owned by the treatment plant.
3. The sludge is hauled the short distance to the trenching area.
At that location, dump trucks back into the trenches from the
open end of the trench and deposit the sludge in 3 to 4 ft (0.9
to 1.2 m) high piles.
4. A bulldozer enters the trench intermittently to push the sludge
into a 5 ft (1.5 m) high accumulation.
5. After each trench is filled to completion, the bulldozer is
employed to spread cover over the 20 ft (6.1 m) wide trench from
the soil stockpiles located on either side. The cover is spread
in a 4 ft (1.2 m) thick application to 1 ft (0.3 m) above
grade.
6. The completed trench is then seeded to promote the growth of
grasses.
10-31
-------
7. Usually settlement of the trenches is not too severe due to the
high solids content of the sludge and the cover thickness.
However, once each year the bulldozer employed for landfilling
operations is used to regrade completed trenches from the
previous year. These trenches are then reseeded.
10.4.3.5 Cost Estimates
The cost estimate prepared for this operation is presented in Table 10-8.
As shown, the total cost was computed at $1,109 per year. Considering a
sludge quantity of 379 wet tons per year (344 Mg per year), this equates
to $2.93 per wet ton ($3.23 per Mg). This represents a savings of $5.07
per wet ton ($5.59 per Mg) when compared to the fee being charged by the
local landfill. Accordingly, plant operators initiated the previously
described operation.
TABLE 10-8
ESTIMATE OF TOTAL ANNUAL COST FOR EXAMPLE NO. 3
Item
Mob Ui zation
Loader
Dozer
Trench Excavation
Covering
Regrading
Seeding
Total
Quantity
2 ea
2 ea
600 yd3
230 yd2
230 yd2
450 yd2
Unit Cost
$50/ea
$50/ea
$0.90/yd3
$0.60 /yd2
$0.30/yd2
$0.36/yd2
Total
$
$
$
$
$
$
$ 1,
Cost
100
100
540
138
69
162
109
1 yd3 = 0.765 m3
1 yd2 = 0.836 m2
It should be noted that costs as low as $2.93 per wet ton ($3.23 per Mg)
cannot be achieved by most treatment plants of this size. One of the
reasons the cost was low was that this plant was able to landfill 6
months sludge in one or two days. Under these circumstances, this
facility was able to achieve economies-of-scale usually found only at
very large sludge landfills.
10-32
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CHAPTER 11
CASE STUDIES
11.1 Introduction
Five case studies are presented in this chapter to illustrate the variety
of existing landfill ing methods. Of the five, one is a narrow trench
operation, two are wide trench operations, one is an area fill layer
operation, and one is a codisposal operation. The five case studies
included in the manual were selected from a total of 22 sludge landfills
that were studied in detail.
11.2 Case Study Summaries
The twenty-two sludge landfills were studied to identify site selection,
design, and operation procedures that are relevant to sludge landfill ing.
In addition, public participation, monitoring, costs, equipment, and
personnel for each site were examined. The data was accumulated via site
visits and interviews with site operators, planners, and designers.
A summary of the above-described information has been compiled on the
next four pages. Figure 11-1 shows the locations of the sites and Table
11-1 summarizes the treatment processes and resulting sludge quantities
for each site. Design and operational features are presented in Table
11-2. Hauling and site costs are detailed in Table 11-3. The data
contained in these compilations was useful in observing trends and
establishing design criteria. As a result, this data formed the basis
for much of the information presented in this manual. The reader may
find it equally useful to peruse this data in determining trends and
criteria relevant to a specific operation.
11-1
-------
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TABLE 11-3
HAULING AND SITE COSTS
Hauling Costs ($)
Site
No.
1
2
3
4
5
6
7
8
9
10A
10B
11
12
13
14
15
16
17
18
19
20
21
22
Pec
yd3
—
__
__
—
—
__
1.57
15.92
4.00
1.42
—
—
4.93
—
__
—
—
__
0.17
—
—
Per
wet ton
—
__
__
—
—
__
1.80
17.90
4.40
1.64
—
—
5.50
—
—
--
—
__
0.22
—
--
Per
dry ton
—
—
__
—
—
—
14.40
83.25
20.00
54.67
—
_.
25.00
—
_.
—
—
__
1.57
—
—
Pec
yd3
0.50
0.91*
2.35
3.03
4.45
2.12
4.16
1.05
28.14
1.06
0.57
1.96*
—
5.83
4.91
_-
1.92
2.37*
1.64
1.03
1.03
__
2.93
Site Costs ($)
Per
wet ton
0.55
1.01*
2.59
3.41
4.98
2.50
4.46
1.21
31.64
1.17
0.66
2.14*
—
6.50
5.35
_-
2.19
2.69*
1.84
1.33
1.17
_-
3.31
Per
dry ton
1.96
4.59
9.25
17.05
22.64
62.50
12.05
10.08
143.82
5.32
22.00
7.13*
__
25.00
16.71
__
10.43
18.17*
9.20
9.50
6.15
__
10.61
* Operating costs only. Does not include site capital costs.
11-5
-------
11.3 Montgomery County, Maryland
11.3.1 Background and History
Site 216 was located in Montgomery County, Maryland about 25 mi (40 km)
east of Washington, DC. It received about half of the total sludge from
the Blue Plains Treatment Plant which serves Washington DC. The plant
uses a step aeration activated sludge process to treat a flow of 309
Mgal/d (13.5 nr/s) with less than a 10% contribution from industrial
sources (Figure 11-2). From this flow the site received about 106,000
wet tons (96,152 Mg) of primary and secondary sludge per year containing
about 20 to 23% solids. The sludge is dewatered using gravity thick-
ening and vacuum filtration. Lime is used in the treatment process to
control pH, stabilize biological activity, and provide odor control.
This contributed another 7,300 dry tons (6,621 Mg) of waste per year. An
additional 2,700 dry tons (2,450 Mg) of ferric chloride and polymers
from the treatment process was produced each year. The site opened in
February of 1976 and closed in February 1978. Narrow trenches were
selected as the landfill ing method.
FIGURE 11-2
BLUE PLAINS TREATMENT PLANT FLOW DIAGRAM
INFLUENT
PRIMARY
kBASINS/J
f
AERATION
BASINS
FINAL
CLARIFIERS
EFFLUENT
15/25%
FILTER
CAKE
11.3.2 Site Description
The site occupied 719 acres (290 ha) of gently sloping terrain. The
highest elevations, 540 ft (165 m) mean sea level (MSL), were located in
the eastern portion of the site and the lowest elevations, approximately
11-6
-------
400 ft (122 m) MSL were found in the western portion. Site 216 was
underlain by the Wissahickon Schist with a saprolite thickness varying
between 20 to 50 or more ft (6 to 15 m) throughout the property. Other
relevant site characteristics are detailed below.
t Topography
• Soil type
Depth to groundwater
Groundwater use
Freezing days
Precipitation
Evaporation
gently sloping; drains to
Anacostia River
silty loam; moderately
permeable
6 to 36 ft (1.8 to 11 m)
aquifer provides potable water
90 days/yr
40 in./yr (102 cm/yr)
47 in./yr (119 cm/yr)
11.3.3 Site Selection
In general, the site selection process established physiographic, econo-
mic and other technical parameters inherent in a desirable disposal site
and then identified suitable areas. The initial parameters included:
• Soils
• Topography
• Geology
• Surface and
groundwater conditions
The first step in the selection process was to delineate suitable areas
of the county based on these considerations. Acetate overlays indicating
unsuitable areas were made for each of these criteria and placed over a
county map. The areas remaining were characterized as "High Priority".
The County used this process to find areas that were generally suitable
for sludge disposal. Some specific sites within the "High Priority"
areas had poor drainage, inadequate soil cover, or other disqualifying
characteristics; conversely, there were sites outside the area that met
the geomorphic requirements of a sludge disposal site.
Using newspaper advertisements, real estate agents, past site inven-
tories, and site visits the county identified 20 potential sites in these
areas. These sites were in turn screened, and those that required ela-
borate modification such as tree cutting or extensive excavation were
eliminated.
A total of 8 potential sites emerged from this process and were subjected
to an in-depth screening based on the following criteria:
11-7
-------
t Site physiography
- expected life of the
- soils and geology
- topography and slope
- screening and buffer
- groundwater
- surface water
site
• Other technical considerations
- zoning and land use
- site availability
- haul route
• Site costs
- haul distance
- site acquisition costs
- site preparation costs
The current site (Site 216) was judged to be the best, based on the above
criteria and on state and county policies outlined in Table 11-4. Figure
11-3 is a map of the site selected. It was purchased rather than leased,
and realtors were notified of the purchase. In addition, several ads
were placed in local newspapers so that the public was aware of the
action.
TABLE 11-4
REGULATORY REQUIREMENTS
AT MONTGOMERY
Jurisdiction
Code
RELATIVE TO SITE SELECTION
COUNTY, MARYLAND
Description of Constraint/Directive
1. Geoloay
2. Soils
3. Topography
4. Groundwater
5. Surface Water
SCS, MSH
SCS, MSH
MSH
MES
SCS, MSH
WRA
6. Buffer and MC
Screening
Restrict site selection where shallow
soil cover over bed rock, and where
sand and gravel is present.
Set site selection criteria according
to permeability, infiltration rate,
runoff and susceptability to flooding.
Site selection - site m Patuxent
watershed, classified as "secondary" or
low priority.
12 percent maximum slope (operation
limitation).
Buffer of 3 ft between the bottom of
the trenches and the highest expected
groundwater table level.
Eliminate sites that drain into
Tridelphia and Rocky Gorge Water supply
reservoirs. Buffer of 100 ft between
streams and trenching operations.
500 ft buffer between trenching
operations and residences or schools.
MC = Montgomery County Department of Environmental Protection
MSH = Maryland State Health
WRA = Maryland Water Resources Administration
SCS = Soil Conservation Service
11-8
-------
There were approximately 719 acres (290 ha) and the land was privately
owned. About 41% of the area was wooded; the remaining area was largely
agricultural.
11.3.4 Design
The county employed a narrow trench that was 2 ft (0.6 m) wide, 3 ft (0.9
m) deep and varied lengths. The intertrench distance was 2 ft (0.6 m)
and cover was mounded 3 ft (0.9 m) over the sludge deposits.
The design and operation insured that the sludge wsa exposed for a mini-
mum time and thus reduced odors, ponding from rainfall, and other un-
desirable events. Usable areas were defined and mapped during the design
process based on soil thickness and depth to groundwater.
11.3.5 Public Participation
11.3.5.1 Public Interaction During the Selection Process
Recognizing the sensitivity of residents to sludge disposal sites,
Montgomery County attempted to use education and communication to defuse
this volatile issue.
After site selection was performed by a consultant, the county held a
public hearing in Rockville, Maryland. Maryland Environmental Services
(MES) made a formal presentation on the proposed site, its operation,
and impact. They encountered opposition from well-organized community
groups based on the fears that the site would generate and release
pathogens into local air and water; that the site would be the source of
objectionable odors, that deliveries would cause increases in noise and
traffic; and that the site would lower property values. The site had
previously been considered for a sanitary landfill and the groups invol-
ved in protesting the selection were largely an extension of opposition
organizations that had formed previously.
The county responded by organizing field trips to the nearby Prince
Georges County trenching site. Transportation was provided by the county
to all interested residents. Despite these efforts the neighborhood
groups filed two suits against the operating agency. Ultimately, the
operation was commenced on schedule in February 1976.
11-9
-------
11.3.5.2 On-going Public Relations
After commencing operations, a mechanism to provide for continuous com-
munication between MES and the neighborhood group representatives was
established. Also, Montgomery County designated one person to personally
handle any complaints from neighbors and other county residents.
11.3.6 Operation
The site operated from 7 a.m. to 6 p.m. with the last half hour being
used for cleanup only. Following is a discussion of the site preparation
and sludge handling procedures during the transfer and on-site phases of
the operation.
11.3.6.1 Site Preparation
The site did not require extensive excavation, but control of drainage,
as in most cases, was critical. Grass diversion ditches, berms, and
swales directed runoff into sediment control ponds. All the ponds had
risers and were constructed to contain a flood equivalent to the largest
5-yr flood anticipated; two of the five ponds had bentonite liners.
Provisions were made to spray irrigate excess pond water as necessary
over completed fill areas.
Based on soil cover and depth to groundwater, usable areas were defined.
Of the total 719 acres (290 ha), 142 acres (57.5 ha) were estabished as
usable and these were scattered throughout the site. Two factors
contributed to this relatively low ratio of usable to total acreage.
First, narrow trench operations are land intensive and second, much of
the land was eliminated because the soil cover was not thick enough to
provide the 3 ft (0.9 m) buffer between trench bottoms and groundwater
required by the State. Access roads to the usable sites were built to be
temporary, with a design life of about one year. As areas were filled,
the roads were removed and the material was reused to make new access
roads. Figure 11-3 shows the network of roads used during the life of
the site.
The entire site was surrounded with a 5 ft (1.5 m) farm fence and the
holding ponds were enclosed within a 6 ft (2 m) fence equipped with a 1
ft (0.3 m) barbed extension. There were two wash pads for the trucks.
The washing area was contained and runoff was directed to the holding
pond. In addition, the facility was equipped with 3 trailers housing
administrative offices, showers and restrooms.
11-10
-------
FIGURE 11-3
SITE LAYOUT PLAN
MONTGOMERY COUNTY, MD
8
•
• MONITORING WELL
! USABLE AREA
11-11
-------
The design incorporated an extensive odor control system that, in retro-
spect, did not function adequately. Four in. (10 cm) perforated PVC pipe
was installed along the perimeter of the site and in the original plan
would have sprayed masking agents when necessary. In practice, site per-
sonnel found spray trucks equipped with "Chemscreen" and "Arrest" which
sprayed masking agents directly on the sludge to be more effective.
It is projected that the final land use will be agricultural. The site,
which closed in February 1978, will remain abandoned and monitored for 5
to 7 yrs.
11.3.6.2 Sludge Loading and Transport
The sludge was loaded on hopper trucks from a railroad car equipped with
three augers. The trucks had a capacity of 72,500 Ib (32,915 kg) or 31
yd^ (24 nr) per truck and included three compartments. The haul
distance was 37 mi (60 km) and the total average number of trips per day
was 30. Prior to reaching the disposal site, the trucks radioed ahead to
alert crews at the disposal area that was currently being used. The
operation maintained two disposal areas at all times and used them simul-
taneously.
11.3.6.3 Operational Procedures
A hose was attached to the top of a hopper truck and the sludge was
forced via compressed air applied at a pressure of 20 Ibs/in.Z (1.4
kg/cm2) through a hose from the bottom of the truck into the hopper of
a high-powered concrete pump. This pump then forced the sludge through a
200 ft (60 m) long, 5 in. (2.7 cm) diameter flexible hose. The hose, in
turn, was guided over the 2 ft (0.6 m) wide trench with a front-end
loader.
Simultaneously, the adjoining trench was excavated by a trencher. The
machine applied soil from the new trench over the trench receiving the
sludge, thus minimizing the time that the sludge was exposed to the
air (see Figure 11-4). The receiving trench was mounded to approximately
3 ft (0.9 m). The last trench was covered with soil from another
source. Figure 11-5 through 11-7 illustrate the operation.
The access roads were placed in such a way as to maximize the usable
areas. In general, the areas were surrounded with two roads joined at
the end and separated by about 215 ft (66 m) of usable area. Completed
areas were hydroseeded or hand seeded with bluegrass.
11-12
-------
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11-13
-------
FIGURE 11-5
NARROW TRENCH
MONTGOMERY COUNTY, MD
FIGURE 11-6
SLUDGE BEING PUMPED INTO NARROW TRENCH
MONTGOMERY COUNTY, MD
11-14
-------
FIGURE 11-7
APPLICATION OF COVER AND EXCAVATION OF NEW TRENCH
MONTGOMERY COUNTY, MD
Relevant operational procedures are summarized below:
Sludge to groundwater - 3 ft (0.9 m)
Soil cover thickness - 3 ft (0.9 m)
Sludge application - 1,275 yd^/acre (2,400 nrYha)
(usable area)
Trench depth - 3 ft (0.9 m)
Sludge time of exposure - <1 day
Total soil usage
(sludge:soil) - 1:1
The following equipment was used at the facility:
No. Machine
2 Rotary trenching machines
2 Track type front end loaders
2 Pumps and air compressors
9 Tractors
24 Trailers
11-15
-------
Following is an outline of problems, together with solutions, encountered
in the operation:
• Frozen ground
- top 3 ft (0.9 m) of soil was removed and stockpiled
• Possible odors near site
- lime was placed on spills and masking agents were sprayed from
trucks
t Mud and dust
- mud wash pad at receiving sites used during inclement weather.
Water and liquid asphalt sprayed on access roads during dry
periods.
11.3.7 Monitoring
The county monitors all wells and surface water within the vicinity of
the site for organic and inorganic pollutants. Sampling for the consti-
tuents found in Table 11-5 is conducted at a frequency varying from one
month to three months depending on the constituents. To date no conta-
mination of surface or groundwater has been noted. The location of the
wells is detailed in Figure 11-3.
11.3.8 Costs
The site cost for each wet ton of sludge was $31.64 ($34.88/Mg) and each
dry ton cost $143.82 ($158.57/Mg). Total disposal costs were $49.54
($54.62/Mg) per wet ton of sludge or $227.07 per dry ton ($254.00/Mg) of
sludge. This relatively high figure reflects the elaborate on-site
safeguards and monitoring, the thorough selection process, and the
relatively long haul distance. Another factor that contributed to this
cost was the high price of land in Montgomery County. A breakdown of
on-site and hauling costs is provided below:
Yd3 Dry ton Wet ton
Hauling costs $15.92 $83.25 $17.90
On-Site costs $28.14 $143.82 $31.64
Total $44.06 $227.07 $49.54
11-16
-------
TABLE 11-5
SAMPLING AND ANALYTICAL PROGRAM
AT MONTGOMERY COUNTY, MD
Monitoring
Type
Groundwater
and surface
water
Well/Station
No.
All wells,
domestic,
on-site
area stream
station
Sample Collection
Technique
Have made a sampl ing
device
Analyses
Parameter(s) Frequency
N03, Cd, Cu, Pb, 1 month
Ni, Cl, Zn, Ca,
Total P, Specific
Conductants, TDS,
TOC
Fecal Coliform, 1/3 month
Chlor HC, Alk, TKN,
N02, N03, N, S04,
Mn, Fe, Zn, Cd, Ni,
Cu, Pb, Hg, K, Mg,
Cr, TOC, NH3-N,
Hardness, Cl, pH,
Ts, BOD, COD, P04,
Ca, Na, Specific
Conductance
11-17
-------
11.4 Waukegan, Illinois
11.4.1 Background and History
The Newport Township landfill, located near Waukegan, Illinois, receives
sludge generated by four treatment plants that serve a domestic popula-
tion of 232 000 with an additional industrial inflow equivalent to 28 000
residents. The industrial inflow originates primarily from a naval base,
a pharmaceutical company and a variety of metal finishing plants. There
plants and one pretreatment wastewater
Sanitary District. The three advanced
sludge, followed by biological denitrifi-
the pretreatment plant uses trickling
filters. Figure 11-8 and Table 11-6 outlines sludge processing at the
wastewater treatment plant. After initial processing, sludge from the
four plants is taken to a processing plant in Waukegan where it is
elutriated and conditioned with lime and ferric chloride. It is then
dewatered to about 22% solids by vacuum filtration (Figure 11-9) prior to
landfill ing. The site commenced operations on July 8, 1974.
are three advanced wastewater
plant within the North Shore
treatment plants use activated
cation and sand filtration;
TABLE 11-6
DETAILS ON SLUDGE TRANSPORTED FROM ORIGINATING PLANT
TO SLUDGE PROCESSING UNIT AT WAUKEGAN, IL
TOTAL
Sludqe Generation Rate
Plant Plant
No. Name
1 Waukeqan
2 Clavey
Road
3 Gurnee
4 North
Chicago
Sludge
Source
Primary
Waste
Activated
Imhoff
Settling
(all)
(all)
(all)
Ibs per
day (dry
solids
weiqht)
13,530
15,409
13,530
11,968
22,965
1.420
qallons
ner day
(wet
volume)
32,446
25,177
27.038
48,643
55,071
3,405
Transport to Processing Unit
days
per
week
5
5
5
5
5
5
mode
8 in. diameter
pipeline
8 in. diameter
pipe! i ne
8 in. diameter
pi pel ine
5,500 gal tank
trucks
8 in. diameter
pi pel ine
5.500 qal tank
trucks
transport
distance
(miles)
<1
<1
<1
22
7.5
5
78,822
191,780
1 Ib = 0.454 kg
1 gal/d = 3.785 L/d
1 in. = 2.54 cm
1 mi = 1.609 km
11-18
-------
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11-20
-------
11.4.2 Site Description
The site has an area of 282.8 acres (114 ha), with 200 acres (81 ha) to
be filled. Soils consist of 2 ft (0.6 m) of topsoil, then 20 to 25 ft (6
to 8 m) of silty clays, followed by 6 to 15 ft (2 to 5 m) of tight blue
clay. The southwestern part of the site is a flood plain with slopes of
less than 1%. The flood plain is not being used for filling operations.
• Topography - slopes average 4%; vegetation sparse;
flood plain on west end has 1% slopes
Soil type - silty clay
Depth to groundwater - 31 to 40 ft (10 to 12 m); perched
table at 25 ft (8 m)
Groundwater use - aquifer provides potable water
Freezing days - 140 days per year
Precipitation - 32 in. per year (81 cm/yr)
Evaporation - 39 in. per year (99 cm/yr)
11.4.3 Site Selection
The first step in the selection process was to identify the disposal
alternatives. The options included:
1. Incineration of dewatered raw and digested sludges
2. Disposal of digested, dewatered sludge on cropland by discing or
plowing into the soil
3. Disposal of digested liquid sludge on cropland by irrigation
4. Landfill ing of dewatered raw and digested sludges
Figure 11-10 illustrates the estimated costs of treatment, transportation
and disposal for each alternative. On the basis of these cost evalu-
ations and a maximum distance of 25 mi (40 km) to the landfill, it was
determined that sludge landfill ing would provide the most cost effective
alternative for ultimate disposal.
Following selection of the disposal alternative, eight potential sites
were chosen based on available data on soils, geology and topography.
Ultimately the Newport Township site was selected for intensive investi-
gation, based on the following considerations:
11-21
-------
FIGURE 11-10
COMPARATIVE COSTS OF SLUDGE DISPOSAL
WITHOUT PHOSPHORUS REMOVAL
AT WAUKEGAN, IL
170
LL. f
O<
160
UJ
3s
Q o
_i
UJ O
O CO
t/5 Q
QUnNTtTIES FIOM NSSD
PLiiNNING AREA WITHOUT
PHOSPHATE REMOVAL.
25
75
100
125
MILES TO DISPOSAL SITE
FROM WAUKEGAN STP
(ONE WAY)
• Short haul distance (10 mi or 16 km)
t Availability of the land for purchase
t A large negative reaction from the public was not anticipated
Accordingly, an option to purchase the land was acquired for this site,
and hydrogeological investigations were begun to determine its environ-
mental acceptability. After discussions with the Illinois Sanitary Water
Board and the Illinois State Geological Survey regarding the data re-
quired to obtain preliminary approval of the landfill site, the District
proceeded with the necessary soil borings and laboratory tests. A total
of nine borings to a depth of up to 52 ft (16 m) were performed at the
site.
11-22
-------
By the end of 1970 the District contracted to have topographic maps made
of the property. The maps of the 450 acre area were prepared at a scale
of 1 in. = 1 000 ft (1 cm = 120 m) and 2 ft (0.6 m) contour intervals.
These maps were provided to a consulting engineering firm that the
District had contracted to prepare design and operation plans for the
site.
11.4.4 Design
The design had to accomodate the following regulatory requirements of the
Illinois State Environmental Protection Agency.
t It had to follow the "Rules and Regulations for Refuse Disposal
Sites and Facilities" (general operational requirements - no
large impacts).
• It was required that a 150 ft (46 m) buffer be placed between
sludge deposits and the property line of any residences and the
center line of any county roads.
• The site could accept only filter cake sludge conditioned with
ferric chloride and lime.
• It was required that groundwater monitoring wells be installed at
state-approved locations. Monitoring for 22 contaminants was
required annually; 5 parameters quarterly.
• It was required that gas monitoring wells at state-approved
locations be monitored for methane, carbon dioxide, nitrogen and
oxygen.
Based on information obtained from borings, excavations were limited to a
15 to 20 ft (5 to 36 m) depth. At this depth, at least 20 ft (6 m) of
silty clay with a low permeability would separate sludge deposits from
groundwater.
Other design considerations included:
• Relatively low solids sludge (22%)
• Deep, well protected aquifer
0 Stable soil for trench sidewalls
• Maximum site usage.
11-23
-------
As a result of these considerations and the site characteristics, the
District chose wide trenches as the disposal method.
In order to determine the stability and seepage characteristics of the
soil, the District excavated two test pits on February 9 and 10, 1972.
Each pit was 24 ft by 50 ft (7 m by 15 m) at ground level. The slope of
three sides was approximately 1:1, the fourth was 1 horizontal to 2
vertical, with a depth of 12 ft (4 m). All observations indicated that
groundwater seepage was not excessive, and that the cuts were stable
since no sloughing or caving of the banks was observed.
An application for a permit to install and operate a sanitary landfill,
together with a detailed installation and operating plan, was then
submitted to the Illinois State Environmental Protection Agency. The
permit was issued on March 2, 1972. In September 1973, a contract was
awarded by the District for preparation of the site in accordance with
plans and specifications prepared by the consultant.
11.4.5 Public Participation
11.4.5.1 Public Interaction During Site Approval
Although when the District initially selected the site they anticipated
little public resistance, protests began following reports of the pro-
posed landfill operation in the media. However, the District performed
detailed environmental impact investigations and prepared an operational
plan designed to minimize impacts. The District worked closely with
various regulatory authorities including:
• Illinois State Environmental Protection Agency
• U.S. Department of Agriculture, Soil Conservation Service
• Lake County Illinois Soil and Water Conservation District
These authorities reviewed and provided input to site plans and reports
throughout the process and as a result of their support, the public
reaction became less negative.
11-24
-------
11.4.5.2 On-going Public Relations
Operational features designed to minimize public resistance were:
• Application of cover over sludge throughout the day in warm
weather to minimize odors.
0 Application of lime over sludge in haul vehicles at all times to
minimize odors.
As a result, the only complaints received to date have been from a resi-
dent whose property is literally surrounded by the landfill. The
resident's complaints are generally justified, and they have been con-
structive in nature. In general, they have centered on odors and noise;
consequently, dumping and operating procedures have been restricted and
currently run from 7 a.m. to 4 p.m.
11.4.6 Operation
Site preparation, sludge loading and transport, and the operating
practices employed are discussed in sections 11.4.6.1, 11.4.6.2, and
11.4.6.3, respectively. Operational considerations are presented below:
Sludge to groundwater - >10 ft (>3m)
Soil cover thickness - 5 ft (1.5 m)
Sludge application - 9,100 yd3/acre (17,200 nr/ha)
Fill depth - 14 ft (4 m)
Sludge exposure - <1 day
Total soil usage
(sludge:soil) - 1:0.6
11.4.6.1 Site Preparation
The existing on-site barn, silo, and minor out-buildings were demolished.
The remaining farmhouse was used as an office. Structures for storing
sludge and on-site equipment were constructed. A paved, all weather
access road was constructed to within several hundred feet of the dis-
posal area. Approaches to the disposal areas were covered with sand and
gravel. A 6 ft (2 m) 'fence was provided for the area south of Ninth
Street (Figure 11-11). Lighting was installed around on-site structures
and sewer, water, and telephone services were in place at the farmhouse.
Prior to excavating a trench the top 3 ft (0.9 m) of soil was stripped
and stockpiled.
11-25
-------
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11-26
-------
11.4.6.2 Sludge Loading and Transport
Sludge from the vacuum filter at the Waukegan sludge processing unit is
transported via a conveyor belt that moves from end to end of a 30 yd^
(23 nr) open dump truck. Thus, sludge is spread evenly over the bed of
the truck. There are five open-top dump trucks with sealed tailgates,
and each makes about 5 trips to the landfill each day. The one-way haul
distance is 10 mi (16 km) and the haul roads are suitable for truck
traffic.
11.4.6.3 Operational Procedures
Individual trenches 20 ft deep, 70 ft long and 22 ft wide (6 m deep, 21 m
long, and 7 m wide) at the top are excavated by a large backhoe/excava-
tor. Sidewalls are straight on all but one side; the 70 ft (21 m) length
on the side where dumping is done has a 6 ft (2 m) wide step halfway down
for added sidewall stability. Thus, the bottom trench width is 16 ft (5
m). Consecutive trenches are constructed with the 70 ft (21 m) sides
parallel. Twenty ft (6 m) of solid ground is maintained between the
parallel trenches and consecutive trenches proceed in a line to form a
single row (Figure 11-11). After completion of one line of trenches, a
second line is begun (as shown in Figure 11-12) to the side of the first
line. Five ft (2 m) of solid ground is maintained between adjacent
rows. The trenches are graded so that leachate can be collected at one
end of the trench and returned to the Waukegan plant for treatment. Haul
vehicles back up on prepared sand and gravel access roads to the long
sides of each trench, and sludge is dumped by the trucks in progression
from one end of the 70 ft (21 m) length to the other.
Usually the consistency of the sludge is such that it flows out to an
even grade inside each trench. However, the bucket of the
backhoe/excavator is used to spread the sludge evenly at the end of the
day. One day's sludge usually accumulates to a 2 ft (0.6 m) thickness.
Filling proceeds to within 2 ft (0.6 m) of the surface before proceeding
to a new eel 1.
At the end of each day, a 6 to 8 in. (15 to 20 cm) soil cover is applied
over the sludge. After filling has proceeded to within 2 ft (0.6 m) of
the subsurface (usually at the end of a week), a 5 ft (2 m) cap of top-
soil cover (previously stockpiled) is applied to 3 ft (0.9 m) above grade
by the backhoe. After initial settlement the trench is final graded and
compacted with small bulldozers (including a D-3 and a D-5). Additional
operational characteristics are detailed below:
11-27
-------
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11-28
-------
The equipment and personnel at the site are as follows
Equipment
1 - Backhoe/Excavator (Northwest with 1.5 yd3
bucket)
1 - Front-end Loader (Hough with 2 yd^ bucket)
1 - Bulldozer (Caterpillar D-3)
1 - Bulldozer (Caterpillar D-5)
Personnel
1 - Superintendent
3 - Equipment Operators
1 - Laborer
Problems encountered during the operation of the landfill, together with
controls are detailed below:
Problem: Freezing temperatures make excavation of cells and
placement of stockpiled cover impossible. Snow and rain make
access to cells by haul vehicles and site operation by equipment
difficult.
Control: During inclement weather, soil is stockpiled on the
site inside a sludge storage building accessible via paved
roads. This building is a steel frame structure 50 ft by 50 ft
by 30 ft (15 m by 15 m by 9 m) high. It is constructed on a
concrete slab with concrete s-idewalls extending 3 ft (0.9 m)
high. A trench drain is located in the middle of this slab to
collect sludge moisture. This leachate is directed to an
underground 10,000 gal (37,850 1) storage tank. Leachate is
pumped out of the tank as necessary and transported via tank
truck to the Waukegan Plant for treatment. In poor weather,
all sludge delivered to the site is dumped
which prevents the addition of moisture from
controls odors. When weather improves, the
back into dump trucks with front-end loaders
cells.
into the building
precipitation and
sludge is loaded
and hauled to the
Problem: Soil runoff from denuded fill areas.
Control: Fill areas are seeded with grasses soon after com-
pletion. All on-site drainage is channeled through sod-lined
ditches to a collection pond.
11-29
-------
. Odors from sludge during transport, from uncovered
sludge in cells during warm weather, from sludge spills, and from
Problem:
sludge i..
equipment
Control: Initially sludge transport was to be in dump truck
trailers covered with tarpaulins for odor control. However,
this caused operational difficulties and transport is now
accomplished in open-top trucks. However, after loading, the
sludge is covered with a layer of lime for odor control while
in transit. In warm weather, sludge in the cells is covered
during the day as well as at the end of the day. Lime is
sprinkled over any sludge spills. The backhoe bucket (which
comes into contact with sludge) is buried in soil at the end of
the day to minimize odors.
• Problem: Mud from site is tracked onto adjoining roadways by
haul vehicles.
Control: A washrack is located at the Waukegan Sludge Proc-
essing Unit. It is used to clean haul vehicles in wet
weather.
• Problem: Noise of haul vehicles and on-site equipment bothers
near-site residents.
Control: Per agreement with nearby residents, hauling and
operation is confined to between 7 a.m. and 4 p.m.
Figures 11-13 through 11-16 illustrate equipment and operations at the
Waukegan site.
11.4.7 Monitoring
Background samples were taken from all wells prior to initiating opera-
tions so that baseline conditions could be established. Subsequent
monitoring has not detected any contamination of groundwater in on-site
wells nor has water from the collection pond and drainage ditches
contaminated surface waters. Establishing initial conditions proved
valuable since one of the local potable wells showed contamination that
could have been attributed to sludge disposal but was known to precede
disposal operations as a result of initial tests.
The number, location, and function of the monitoring wells was estab-
lished in conjunction with the Illinois State Environmental Protection
Agency. Figure 11-11 illustrates the location of the wells and Tables
11-7, and 11-8 detail the wells and monitoring parameters.
11-30
-------
FIGURE 11-13
STOCKPILING SOIL
WAUKEGAN, IL
FIGURE 11-14
UNLOADING SLUDGE INTO WIDE TRENCHES
WAUKEGAN, IL
11-31
-------
FIGURE 11-15
PLACING INTERIM COVER
WAUKEGAN, IL
FIGURE 11-16
PLACING FINAL COVER
WAUKEGAN, IL
11-32
-------
TABLE 11-7
SUMMARY OF GROUNDWATER AND GAS WELLS AND SURFACE WATER STATIONS
AT WAUKEGAN, IL
Relation to Fill Well
Monitoring
type
Groundwater
Gas
Leachate
Surface
Water
Well /station
no.
OW-1
OW-2
OW-3
OW-4
OW-5
OW-6
OW-7
OW-8
OW-9
OW-10
5 Potable
Wells
Gas Well 1
Sludge cell
Tank under
sludge
storage
building
Runoff pond
Drainage
ditches
Location
(up- or down-
gradient)
Down-gradient
Down-gradient
Up-gradient
Up-gradient
Up-gradient
Up-gradient
Up-gradient
Down-gradient
Down-gradient
Down-gradient
Down-gradient
In-sludge
—
~
Specifications
Total Depth below
Distance depth groundwater Drill rig
(ft) (ft) (ft) used
200 30
100 30
100 30
20 30
100 30
100 30
100 30
100 30
100 30
100 30
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11-34
-------
11.4.8 Costs
A breakdown of the on-site costs reveals that the cost per dry ton of
sludge was $10.61 ($11.70/Mg). The costs were calculated in the
following manner: first capital expenditures were divided by the total
amount of sludge received over the life of the site; next operating costs
were divided by the amount of sludge received for the period considered
(6 months in this case); finally the figures were added to arrive at the
total cost per unit of sludge (excluding hauling costs). The intensive
use of the available land contributed to this relatively low figure.
The following tabulation is a breakdown of the costs by category.
Hauling costs have not been included in the total cost.
Total Cost Unit Cost
(T)($/dry ton sludge)
Site Capital Costs
Land $ 450,000 $2.25
Monitoring Wells 12,000 0.06
Site Preparation 328.000 1.64
Total Capital Cost $ 790,000 $3.95
Site Operating Cost (October 1977 through March 1978)
Labor $ 18,200 $3.64
Equipment Depreciation 16,450 3.29
Administration 7,300 1.46
Maintenance 6,850 1.37
Laboratory 1,450 0.29
Fuel 1,250 0.25
Operating Materials & Supplies 900 0.18
Miscellaneous 650 0.13
Total Site Operating Cost $ 53,050 $10.61
11-35
-------
11.5 Colorado Springs, Colorado
11.5.1 Background and History
The Colorado Springs landfill is located on Drennan Road near Peterson
Field. The operation uses two landfill ing methods: narrow trench and
wide trench. The focus of this study will be restricted to the wide
trench operation. The current flow of the treatment plant is 24 Mgal/d
(1.1 nr/s) and the plant is designed to handle up to 30 Mgal/d (1.2
nr/s) from a population of 230,000. Industrial impact is presently
being studied, but Colorado Springs does not require pretreatment of
industrial effluents at present. In general, the sludge has a lower
heavy metals content than typical municipal sludge. The treatment plant
has bar screen separation, primary clarifiers, and waste activated sludge
treatment. Using gravity thickening and vacuum filtration the sludge is
dewatered to about 20 to 25% solids. Although the site began operations
in 1970, wide trench disposal did not begin at the site until July 1976
and terminated on December 19, 1977.
11.5.2 Site Description
Topography - rolling hills <8 % slopes
Groundwater use - windmill aquifer - provides drinking
water
Soil type - silt and clay
Depth to groundwater - >10 ft (>3 m)
Freezing days - 120/yr
Precipitation - 13 in./yr (51 cm/yr, mostly snow)
Evaporation - 60 in./yr (152 cm/yr)
11.5.3 Site Selection
The Peterson Field site was selected because it offered significant ad-
vantages:
• Extended site life
• Land was owned by the city
t Short haul distance
• Site was fenced and area was sparsely populated
After the selection was made operations were begun immediately. There
were no further selection criteria considered and no preparation of
design or operation reports. Interaction with local, state and federal
government was limited. Although not employed as selection criteria,
both the amount of soil available and the topography were favorable for
landfill ing.
11-36
-------
11.5.4 Design
There were no design plans or site alterations made prior to initation of
operations since the site was relatively flat and required no altera-
tions. Wide trench operations were restricted to upland areas and sur-
face runoff was controlled by the orientation of trench and fill (out-
lined in more detail in Operation 11.5.6).
11.5.5 Public Participation
Public interaction did not begin until a few years after the opening of
the site, when a housing development was built near the site and along
the haul route. The residents complained of odors from accumulated
sludge piles. Following those complaints city officials instructed site
personnel to cover sludge as it was received. However, complaints
continued from both nearby residents and airport officials. Accordingly,
city officials decided to relocate the site in December 1977, despite the
fact that a considerable amount of usable area remained.
11.5.6 Operation
The site operated 7 days a week from 6 a.m. till 10 p.m. The wide trench
operation received a total of 6,200 dry tons (5,624 Mg) of sludge with a
solids content of 22% over the 17-month life of the operation. Site
preparation, sludge transport and disposal operations are discussed in
the following sections.
11.5.6.1 Site Preparation
Fencing and other facilities were in place at the inception of the dis-
posal operation. The site's topography was compatible with the disposal
method and vegetation was sparse; consequently excavating and grubbing
were not necessary. Preparation consisted mainly of digging the wide
trenches. Contractors did the excavations which were 60 to 80 ft wide
(18 to 24 m); 600 to 800 ft (183 to 244 m) long; and 6 to 8 ft (2 to 2.5
m) deep. The trenches were located on upland areas with the long axis of
the trench perpendicular to the slope. The location of these pits on
high ground, and the soil stockpiles on the uphill side prevented accumu-
lation of water. Between 20 and 25 ft (6 to 8 m) of ground separated the
trenches.
11.5.6.2 Sludge Loading and Transport
The one-way haul distance was 7 mi (11 km) and the roads were compatible
with heavy truck traffic. In addition, the route traversed a rural area
11-37
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and minimized the impact of transport on residents. The sludge was
placed into uncovered dump trucks with sealed tailgates and varying
capacities directly from the vacuum filters. The three vehicles made a
total of ten trips per day.
11.5.6.3 Operating Procedures
Dump trucks hauling sludge entered the trenches through the ramps and
deposited sludge at the opposite end as shown in Figure 11-17 and 11-18.
Dumping took about 2 or 3 minutes maximum for each load. Each load was
dumped on fresh ground. That is, sludge loads were not dumped atop
previous loads. Typical pile heights were 4 ft (1 m).
FIGURE 11-17
SCHEMATIC OF OPERATING PRACTICES
AT COLORADO SPRINGS, CO
DUMP TRUCK
ACCESS RAMP
COVER SOL
STOCKPILE
BULLDOZER
COVERING SLUDGE
PLAN VIEW
COVER SOIL
STOCKPILE
SLUDGE
SECTION A-A
Two bulldozers applied daily cover over sludge piles. Usually one dozer
pushed the cover soil stockpiled on one long side of the trench out over
the 4 ft (1 m) high sludge piles, while the other dozer pushed the cover
soil from the other long side. Cover was usually graded 4 ft (1 m) thick
(see Figure 11-17 and 11-18).
11-38
-------
o o
1—1 O
CO
i— C£
\ UJ CD
i— 0. -ZL
r— O >— i
0£ C_) 00
13 z:
CJ3 UJ O
LU O
Q _J
i-c O
11-39
-------
It was found that this thickness was required before the soil could
safely support equipment.
Additional operating characteristics are detailed below.
SIudge to groundwater - >5 ft (2 m)
Soil cover thickness - 4 ft (1 m)
Sludge application - 4,700 yd3/acre (8,883 m3/ha)
Fill depth _ 4 ft (1 m)
Sludge exposure (days) - <1 day
Total soil used
(waste:soil) -1:1
The information below outlines the equipment and personnel required to
operate the site.
Equipment Time Personnel
Caterpillar D-6 1/2 (20 hrs/wk) 1/2
Caterpillar D-8 1/2 1/2
Scraper 1/4 (10 hrs/wk) 1/4
TOTAL 1-1/4 (50 hrs/w) 1-1/4
The equipment used was not specifically selected for this operation, but
was chosen from available equipment already owned by the municipality and
was used for both narrow and wide trenching and occasionally, other
operations.
The only facilities located on the structure were a camper shell and
chemical toilet.
Following is an outline of problems associated with the operation of the
site and the controls used:
o Problem: Wet and snowy weather causes access problems for haul
vehicles. Access roads on the site are dirt (not paved) and
become slippery or muddy (in snowy or wet weather, respectively).
Driving loaded trucks on public paved roads in such weather is
also hazardous. This has resulted in several small accidents in
the past.
Control: Hauling is discontinued and site closes down in
severe weather. This happens for an average of 10 days each
year. The treatment plant has about 30 to 40 days storage
11-40
-------
capacity for sludge when the site is closed.
tractors can be used and have been used to haul
sludge when site operations resume.
Further, con-
the backlog of
• Problem: Despite daily cover, because sludge is not digested or
otherwise stabilized, odor can be a problem in warm weather and
complaints are received from nearby residents.
Control: Cover was applied several times during the course of
the day in warm weather.
• Problem: Rainfall which collects in the pits caused problems
with haul vehicles becoming stuck in the mud. Dust was a problem
in dry weather and nearby residents complained regularly.
Control: A layer of fresh dry soil was applied in the pits to
improve maneuverability by haul vehicles in wet weather. A
water tank truck with a spray bar was used to apply water to
on-site dirt roads in dry weather.
• Problem: Strongest complaints from nearby residents concerning
the subject site were directed at noise from equipment and from
haul vehicles on the site, and increased traffic from haul
vehicles on public roads.
Control: None practiced to date. Public officials attempted
to placate nearby residents by assuring them that the disposal
operation were soon to be dis con inued at the site.
t Problem: Flies were attracted to and breed in sludge at the
site. Nearby residents complained, particularly in warm
weather.
Control: Sludge was sprayed with a disinfectant in the summer
to keep the flies down. This disinfectant is the type normally
used on livestock to protect them from flies.
Figures 11-19
site.
and 11-20 illustrate the operational procedures at the
11.5.7 Monitoring
Several months after the site was established, the city began to monitor
existing on-site wells to determine the impact of the site, if any nn
on
+j ---------- - - ___. ._ _.._
the Windmill Aquifer. This was motivated by a desire on the part of city
officials to allay public concern and hence extend the site life. Figure
11-21 shows the location of the monitoring wells.
11-41
-------
FIGURE 11-19
WIDE TRENCH
COLORADO SPRINGS, CO
FIGURE 11-20
APPLYING COVER TO SLUDGE DEPOSITS
COLORADO SPRINGS, CO
11-42
-------
FIGURE 11-21
SITE LAYOUT PLAN
AT COLORADO SPRINGS, CO
DRENNAN ROAD
LEGEND
'0 MONITORING WELL
11.5.8 Costs
The total cost per dry ton of sludge including hauling costs was $25.32
($27.92/Mg). The costs were derived by dividing the quantity of sludge
received in a year by the annual haul and operating costs. Site costs
were significantly reduced since the land was owned by the municipality
initially. Also, investigations indicated that extensive environmental
controls were not necessary. Together with the short haul distance these
factors contributed to the low handling costs outlined below.
11-43
-------
Total Cost Unit Cost
[T](J/dry ton)
Haul Cost $ 87,600 $20.00
Site Capital Costs (None since land was free)
Site Operating Cost
Equipment and Personnel
for Trench Excavations $ 7,700 $ 1.76
Equipment and Personnel
for Covering Pits $ 15,600 $ 3.56
Total Site Operating Cost $ 23,300 $ 5.32
Total Cost $110,900 $25.32
The costs presented are based on the operating cost of the landfill for a
single year and the total amount of sludge received (4,380 dry tons
(3,970 Mg)) for a one year period.
11-44
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11.6 Denver, Colorado
11.6.1 Background and History
The Denver disposal site is located 26.2 mi (42 km) southeast of the
Metro treatment plant off state highway 30 in the Lowery Bombing Range
(LBR). The plant processes approximately 100 Mgal/d (4.4 irr/s) and
serves a population of 1,100,000. About 15% of the inflow is from
industries, including slaughter houses, plating industries, chemical
manufacturers, and office buildings. The plant produces thickened waste
activated sludge (WAS) and the Denver Northside (DNS) treatment plant
contributes primary digested sludge. This mix is pumped to a processing
building where lime, ferric chloride and/or polymers are added to aid
vacuum filtration. The sludge has a 15% solids content and the plants
contribute 100 dry tons (90 Mg) per day with the following constituents:
Raw primary
Anaerobic, digested
WAS, digested
Fed 3
Lime
40%
15%
45%
8-12% dry weight
20-30% dry weight
Figure 11-22 outlines the treatment processes and sludge characteristics
of contributing plants. The site uses two disposal methods; the primary
disposal method is an application technique that incorporates the sludge
into the soil by cultivation. The alternate method, area fill using
layering, is employed in cold weather. This technique was initiated in
1973 and will be the focus of this case study.
FIGURE 11-22
WASTEWATER TREATMENT FLOW DIAGRAM
FOR DENVER, CO METRO PLANT
To
Sludge Treatment
and Beneficial
Reuse or
Disposal
DNS Digested
Primary Sludge
Primary Sludge
Influent
Wastewater
Waste Activated
Sludge
Effluent
South Platte
River
Return Activated
Sludge
11-45
-------
VI .6.2 Site Description
The site has a total area of 1,450 acres (587 ha) and 650 acres (263 ha)
are being used for the area fill operation. The climatic and physio-
graphic characteristics at the site are detailed below.
Topography - gently rolling hills; low relief
Soil type - clay, sand and gravel
Depth to groundwater - 10 to 140 ft (3 to 43 m)
Groundwater Use - aquifer provides potable water
Freezing days - 240/yr
Precipitation - 14 in./yr (36 cm/yr)
Evaporation - 60 in./yr (152 cm/yr)
11.6.2.1 Soils and Geology
The surficial geology of the area consists of two principal units: (1)
alluvium consisting of unconsolidated, poor- to moderately well-sorted
clay, silt, sand, and gravel of Pleistocene and Holocene age with a
maximum thickness of about 25 ft (7.6 m); and (2) the undifferentiated
Denver and Dawson Formations consisting of brown, dusky-yellow, and
blue-gray mudstone with thin, lenticular beds of lignite and gray sand-
stone.
The dominant soils at the LBR are the Fondis and Renohill series. The
Fondis soils are deep well-drained soils located on uplands, and formed
from loessol deposits overlying the Dawson formation (Pleistocene Age).
The Fondis surface soil is about 10 cm thick, free of lime, very dark
grayish-brown and silt loam or silty clay loam in texture. The subsoil
is 41 to 46 in. (102 to 114 cm) thick, contains free lime, is dark
yellowish brown in color and silt loam to clay in texture. The Fondis
soils have a moderately slow permeability, slow internal drainage and
high available water holding capacity. The Renohill series which has
developed on the Dawson formation is a moderately deep well-drained soil.
The surface layer is about 4 in. (10 cm) thick, free of lime, and is dark
brown loam. The subsurface soil is approximately 25 in. (63 cm) thick,
contains free lime, dark brown to dark yellowish brown in color, and
ranges from a loam to silty clay loam in texture. Renohill soils have
medium internal drainage, moderately slow to slow permeability and
moderate water holding capacity.
11.6.3 Site Selection
No site selection process was employed. The city of Denver purchased the
land in the 1950's from the Federal government for the expressed purpose
of solid waste disposal. In 1969, Metro acquired disposal rights to the
11-46
-------
land from the city and county of Denver. As a result, no pre-selection
investigations were conducted.
11.6.4 Design
There was no design process, but through trial and error two operating
methods were established. The first was a land application method, the
second an area fill procedure used only in inclement weather. The
topography of the site was conducive to both disposal and application.
11.6.5 Public Participation
Due to the remoteness of the site there was no interaction with the
public during the site approval phase. Beginning in 1972, complaints
were registered by residents who lived near LBR.
As a result, the Arapahoe County commissioners conducted a public hearing
and invited Metro to attend. The complaints centered on objectionable
odors associated with the site. These were a consequence of unauthorized
operational changes in disposal practices. Metro proposed the current
method of disposal at the meeting and it was approved. Implementation
began immediately.
11.6.6 Operation
Sludge disposal began in 1969 and is expected to continue until 1980
giving the site an 11 year life. The site is open 24 hours a day. The
area fill operation takes place in locations where the topography is
charcterized by rolling hills. Operational considerations are outlined
below.
Sludge to groundwater - 10 to 140 ft (3 to 43 m)
Soil cover thickness - N/A
Sludge application - 9,000 ydj/acre (17,010 nr/ha)
Fill depth - 17.5 ft (5 m)
Sludge exposure - <1 day
Total soil usage
(sludge:soil) -1:5
11.6.6.1 Site Preparation
Large earthen berms are constructed from soil excavated onsite. The
excavation occurs on the top of hills, thus lowering the overall eleva-
11-47
-------
tion. These berms are constructed in an Intersecting orientation,
similar to a "tic-tac-toe" configuration. The berms are approximately 20
ft (6 m) in height, several hundred feet in length, and approximately 15
to 20 ft (4.6 to 6 m) in width at the top and are slanted slightly to
allow for runoff of water. The berms are constructed in the summer when
conditions permit.
11.6.6.2 Sludge Transport
The distance from the sludge source to the disposal site is 26 mi (46
km), one-way. There are 27 to 30 loads delivered daily. Three 1978 Mack
Road Tractors and one 1975 IHC Road Tractor are used to haul the sludge
and smaller dump trucks ha/idle the sludge on-site. The haul vehicles
have Ji capacity of 40 yd1-5 (30 nr) and the dump trucks hold 13 yd1-5
(10 m3}.
The haul vehicles deposit the sludge into sludge storage hoppers at the
site. It is then loaded into the smaller dump trucks and delivered to
the sludge disposal area.
11.6.6.3 Operational Procedures
The dump truck drives down one berm, turns around, and backs up down the
other berm. The configuration or orientation of the berms is such that
it cuts down on the length and amount of time needed for backup. The
distance that the drivers have to back up is also reduced, which can be
important at night and/or when there is inclement weather.
Sludge is dumped from the trucks positioned at the edge of the berm.
The dozers located below begin to mix the sludge back and forth between
them with the soil from the berm (Figure 17-23). The sludge soil mixture
is generally one part sludge to five or six parts soil. As the berm
becomes shorter and eventually meets one of the intersecting berms, this
intersecting berm then becomes the unloading-working area (Figure 11-23),
thus keeping the backup distance to a minimum at all times. Figures
11-24 and 11-25 illustrate equipment used at the landfill.
Once an area has been worked during the winter operation, the following
winter's operation occurs on top of that, thus, in effect, burying the
sludge-soil mixture of that previous year with the current years'
sludge-soil mixture. This layering of each year's mixture combined with
excavation of the soil from hilltops has the effect of lowering the
hills, filling in low areas, and generally creating a flatter land than
was originally present.
11-48
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ro LU
CM Q-
I O O
UJ >- C£.
OZ
-------
FIGURE 11-24
HAUL VEHICLES
DENVER, CO
FIGURE 11-25
SLUDGE MIXING EQUIPMENT
DENVER, CO
11-50
-------
The following equipment and manpower is used primarily for the sludge
landfill operation. However, some of this equipment is also used for the
sludge land application that occurs during favorable weather conditions.
Quantity
1
1
1
1
1
1
1
1
1
1
3
3
5
Description
21
1977 Dozer, Fiat All is w/ripper, 21C
1977 Dozer, Fiat All is, 21C
1977 Grader, Huber, 850
1972 Scraper, Michigan, 210
1977 Front End Loader, Case, W24B
1974 Office Trailer, Elder, 12E797551
1975 Pickup, Dodge, 12E898962
1975 Station Wagon, Plymouth, 12E898961
1977 Pickup, Dodge 4x4, 12M84227
1975 Road Tractor, IHC, 12E900075
1978 Road Tractor, Mach, 12M103279-81
1977 Dump Truck, IHC, 12M102631-33
1973 Dump Trailer, Steco, S3270
TOTAL
Purchase Price
$ 132,217
119,403
17,600
40,000
42,985
4,455
3,286
4,830
4,830
25,950
32,656/unit
26,860/unit
6,500/unit
$ 606,604
Personnel:
1 Director
1 Environmental Agronomist
1 Field Supervisor
1 Mechanic
10 Field Operators
0.5 Secretary
14.5 TOTAL
11.6.7 Monitoring
In 1974 to 1975, approximately 5 years after disposal began, extensive
monitoring of soils, surface and groundwater was initiated in cooperation
lif 1 ^ n 4* M ^ MC^Q C ^tYi rt T 4 « ^"i *• ^v\f\ ^i/\irt/\ f* f\m 4 ^v^v^ii^llt/ £ r\ v* r\ ^» r* \r\
"t" rlpi
Samplings are done semi-annually for each.
Two wells are located immediately down slope of the burial areas. Leachate
from the sludge appears to be affecting the water quality near the two
wells since both exhibit significant deviations from background wells,
particularly with regard to nitrates, chloride, ammonia, and magnesium.
Moreover, sulfate and manganese concentrations exceeded EPA's recommended
drinking water standards.
11-51
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11.6.8 Costs
The major costs associated with this site are outlined below.
item Total Cost Unit Cost
(I) ($/dry tons)
Hauling Cost (Unknown)
Site Capital Costs (Annual 1 zed and budgeted for 1978)
Land 60,000 1.93
Total Capital Cost 60,000 1.92
Site Operating Costs (Budgeted for 1978)
Regular wages 349,361 11.19
Overtime wages 19,707 0.63
Materials 45,200 1.45
Fuel, oil 4 gasoline 60,176 1.93
Outside services 82,410 2.64
Chemicals 4,200 0.13
Electricity 6.420 0.20
Total Site Operating Cost 567,474 18.17
Total Cost 627,474 20.09
The above costs represent the annual combined costs of operating both the
landfill and land application operation. Separate cost accounting is not
maintained for the two operations and therefore accurate cost figures on
the landfill operation alone are not available. However, site operators
report that the total annual cost of the landfill operation is the same
as the total annual cost of the land application operation despite the
fact that the landfill is used an average of only two months (in the
winter) each year. At 100 tons per day the site receives 31,285 tons per
year (100 t/d x 6d/7d x 365 = 31,285). Assuming then, that half of the
total site cost is used for the landfill ($313,737) and that only
one-sixth of the total sludge received is attributable to the landfill
(5,200 dry tons (4,720 Mg)), the cost of sludge landfilling is $60.33 per
dry ton ($66.51/Mg).
11-52
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11.7 Lorton, Virginia
11.7.1 Background and History
Located off of Interstate 1-95, south of Washington, D.C., the Lorton
site is a codisposal facility that serves 5 treatment plants (from 4
municipalities) and provides wastewater treatment for approximately 2
million people. The industrial inflow is relatively small since the area
is not industrialized. The site handles 58,630 wet tons (53,177 Mg) of
sludge per year with an average solids content of 22%. In addition,
another 490,000 tons (441,430 Mg) of refuse are dumped each year at the
site. Table 11-9 outlines the treatment plants and resulting sludge
types that are processed at the site. Although no regulations exist in
Virginia that apply directly to sludge disposal, the facility had to
receive authorization from the Virginia State Bureau of Solid Waste and
Vector Control and the Virginia State Water Control Board before starting
operations. Ultimately, permission was granted to dispose of up to 300
tons (272.1 Mg) of sludge per day at the Lorton site. The Washington
D.C. federal prison complex is located on the site. Operations began in
1972.
TABLE 11-9
SUMMARY OF SLUDGE GENERATION AND TRANSPORT TO LORTON, VA
Source
Washington
(Blue Plains)
Alexandria
Fairfax
County
Arlington
County
Sludge Generation
Sludge
Treatment
Anaerobic Digestion,
Dewatering
Anaerobic Digestion,
Dewatering
Anaerobic Digestion,
Lime and Fed
Addition,
Dewatering
Incineration
Percent
Solids
20%
20%
20%
95%
Quantity
(wet tons per
year)
12,313
10,554
34,006
1,759
Sludge
Vehicle
Tractor trailers with
sealed tailgates
Tandem-axle dump-
trucks with sealed
tailgates
Roll-off containers
on small trucks
Tandem-axle dump-
trucks with sealed
tailgates
ransport
Capacity
Each
(tons)
15
7-8
5
7-10
Average
Trips
Per Pay
4 or 5
7 to 10
25
1 or 2
Haul
Distance
Miles
20
12
8
18
1 ton = .907 Mg
1 mi = 1.609 km
11.7.2 Site Description
The site was located at the top of a topographic divide and the slopes
were variable. In general, slopes within the actual disposal area did
11-53
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not exceed a 25% grade. The usable area, located near the Lorton prison
complex, was free of trees.
Soils in the area had a medium permeability and consisted primarily of
fine sands, silt, clay and gravel. The bed rock outcropped frequently in
the area of the landfill.
A stream bisected the usable area and cut a valley with a 25% slope. The
disposal operations are conducted along the sides of the stream valley.
The groundwater varied in depth from 40 to 0 (springs) ft (12.2 to 0 m)
below the surface. Springs and streams were protected and culverted in
the disposal area.
• Topography
Soil
Depth to groundwater
Groundwater use
Freezing days
Precipitation (in.)
Evaporation (in.)
Surface water
- upland with slopes no greater than
25%
- sand, silt, and clay
- 0 to 40 ft (12.2 to 0 m)
- the aquifer is not currently used
as a source of drinking water
- 85 days/yr
- 41 in./yr (104 cm/yr)
- 47 in./yr (120 cm/yr)
- stream roughly bisects site
11.7.3 Site Selection
The following factors were important in the site selection process:
• The land was already owned by Wasington, D.C.
t The site size allowed a life of approximately 20 years
• The haul route used interstate roads and other major arteries to
within a few miles of the facility.
Since the land was owned by Washington, D.C., the 3,000 ac (1,215 ha)
Lorton site was the logical choice for a landfill. Consequently, the
selection process consisted largely of evaluating the location. This was
an extremely comprehensive investigation and relevant impacts were
thoroughly examined.
Evaluation of the facility showed that nearly all aspects of the site
were conducive to landfill operations. The factors evaluated included:
11-54
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• Topography
• Soils
• Geology
• Surface and groundwater
As a result of the investigation, 800 ac (324 ha) were made available for
"resource recovery, land reclamation, an d re reation". Of this 290 acre
(117 ha) were allocated for land reclamation via sanitary landfilling.
11.7.4 Design
The design criteria employed called for a site life of 18 years. Other
design considerations included:
• Adequate Slopes - the slopes had to be steep enough to promote
drainage but not so steep that erosion would occur.
• Screening and Buffers - small buffers had to be maintained
between the landfill and the prison complex and between the site
and roads and residences adjacent to it.
t Groundwater - as a result of investigations conducted by a
consulting geologist, it was decided that 2 ft (0.6 m) of
natural soil would provide a sufficient buffer between
sludge/refuse deposits and the groundwater table. The decision
was based on the attenuative properties on the in situ soil.
t Surface Water - upland drainage was diverted around the fill
area and on-site streams were protected by installing culverts.
Siltation ponds were constructed to contain runoff.
The design identified 20 fill areas that were to be used successively.
Clearing and grubbing was performed on the areas only as they were used.
In general, the excavation was restricted to the amount needed to provide
cover for each segment of the disposal operation. Two phases were estab-
lished, the first to consist of filling operations along both sides of
Mills Branch Creek, the second to be done over the creek's stream valley.
Figure 11-26 is a map of the usable areas.
In assessing the amount of soil needed, the design assumed a 20%
shrinkage, and a final soil/sludge refuse mix with a 3:1 ratio.
The Lorton facility required both an interim landfill operating permit
and a full-scale landfill operating permit. Accordingly, several reports
and design plans had to be submitted to the Virginia State Bureau of
Solid Waste. These included:
11-55
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FIGURE 11-26
SITE PLAN LAYOUT
AT LORTON, VA
SCALE \ = 1000
LEGEND
SURFACE WATER COURSES
ACCESS ROAD
-—PROPERTY BOUNDARY
LIMITS OF LANDFILLING OPERATIONS
ACTIVE FILL AREAS
WOODED AREAS
SITE MONITORING WELL
PROJECT MONITORING WELL
o
SITE SURFACE WATER
MONITORING STATION
11-56
-------
A geologic report
A design report
A site preparation plan
A phased fill and covering plan
An operational procedures report
11.7.5 Public Particiption
11.7.5.1 Public Interaction During Site Approval
Considering the size of the landfill, the amount of refuse and sludge
handled, and the fact that much of it comes from outside the jurisdiction
of Lorton, public reaction was mild. One explanation for this was that
the public was somewhat more preoccupied with the District's penal faci-
lity, also located at the Lorton site.
The greatest concern demonstrated by the public was criticism of traffic
noise and spilled waste on Furnace Road. There are 5 residences fronting
this road on the 3 mi (4.8 km) section connecting 1-95 to the disposal
site. Noise level investigations were conducted to prove that noise
levels were tolerable, but public criticism continued until ultimately a
new 3 mi (4.8 km) stretch of road was constructed for the haul vehicles
parallel to Furnace Road.
11.7.5.2 On-going Public Relations
Public criticism of the landfill has been continuous, with most com-
plaints centering on odor and spilled refuse. On-site operators have
taken steps to accommodate complaints from area residents.
To reduce odors, operators cover the sludge at the operating face daily
whenever possible. When sludge is stockpiled over the weekend, masking
agents are used. Complaints concerning spilled refuse are handled
immediately by on-site crew men. Upon receiving a complaint a crew is
dispatched to handle it. It is hoped that this cooperative approach will
help to. develop a sense of goodwill between the area residents and the
landfill operation.
11.7.6 Operation
The site operates 5 days a week from 5 a.m. to 8 p.m. Following is a
discussion of the site preparation, hauling, and disposal procedures.
11-57
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• Sludge to groundwater - 2 ft (0.6 m)
• Soil cover thickness - 0.5 to 2 ft (0.2 to 0.6 m)
• Sludge exposure - <1 day
• Total soil usage
(waste:soil) - 1:0.33
11.7.6.1 Site Preparation
Since the landfill occupies the top of a topographic divide no upland
drainage flows into the site. All springs and streams on the site are
protected by culverts and runoff is collected in on-site basins.
The entire area was surrounded by a chain link fence, electricity was
provided for lights on the access roads and operating face; sewer hookups
were provided for the weigh station and office.
11.7.6.2 Sludge Transport
The sludge was hauled on interstate 1-95 to within 3 mi (4.8 km) of the
disposal site. The road was designed to handle heavy trucks and could
easily accommodate the impact of increased traffic. A separate access
road was constructed to handle traffic from 1-95 to the site. The
distance from the various treatment plants are summarized in Table 11-9.
All roads on-site were paved with asphalt and approached within 1/4 mi
(0.4 km) of the operating face.
11.7.6.4 Operational Procedures
Approximately a year before a fill area is to be used it is excavated and
grubbed. The operation is basically an area fill and occurs on slopes.
Successive sludge/refuse mixtures are layered on the face of the slope
and covered with an interim soil cover. Figures 11-27 through 11-30
illustrate the operational procedures described below.
The process starts with refuse being dumped at the toe of a lift and
worked uphill. Sludge is then dumped on top of the slope and is worked
downhill. The two are then thoroughly mixed (see Figure 11-31). Before
closing down for the day 6 in. (15.2 cm) of soil is applied. An interim
cover of 12 in. (30.4 cm) of soil is placed when the lift is completed.
At the conclusion of phase I filling operations a final 24 in. (60.9 cm)
soil cover will be applied.
Originally sludge was not disposed of on the operating face, but was
disced into the soil in order to enrich the relatively infertile in situ
11-58
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FIGURE 11-27
SPREADING SLUDGE OVER REFUSE
LORTON, VA
i
FIGURE 11-28
SLUDGE AT WORKING FACE
LORTON, VA
11-59
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FIGURE 11-29
COVERING SLUDGE/REFUSE MIXTURE
LORTON, VA
FIGURE H-30
GRADED SITE
LORTON, VA
11-60
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11-61
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soil. However, this practice is not used as frequently since frozen
ground and/or unsuitable topography often prevent discing operations.
Additional operational features are presented below.
The equipment used in the operation is as follows:
Equipment Type No.
Landfill Compactor 1
Tracked Bulldozer 5
Scrapers 3
Rubber-tired Front End Loaders 2
Grader 1
Miscellaneous 5
TOTAL 17
Personnel requirements are as follows:
Quantity Job Title
8 Supervisor
13 Equipment & Truck Operators
18 Laborers
4 Weigh Station Operators
4 Other
47 TOTAL
11.7.7 Monitoring
Monitoring of both surface and groundwater is being conducted at 2 month
intervals. Table 11-10 indicates the monitoring parameters used. Figure
11-26 shows the location of gauging stations and test wells.
Surface water monitoring has not detected any additional contamination
from the landfill. Readings from the upstream and downstream stations
have been consistent. On the other hand, groundwater monitoring revealed
that detectable but small amounts of contaminants are leaching from the
fill. Lead and iron are the main contaminants monitored in the wells
down gradient. Three types of wells are used to monitor groundwater and
gas simultaneously.
11-62
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TABLE 11-10
SAMPLING AND ANALYTICAL PROGRAM AT LORTON, VA
Analyses__
Monitoring Well/Station Sample Collection ----- - TotaTTimes
Type No. Technique Parameter (s) _ to Date F requency
Groundwater BG PVC bail sampler Cd, Cr, Cu, Fe, Hg, Ni, 9 every 2 ir.onths
US-1 Pb, Zn, Cl , S04, TOC
Leachate IR
Gas IR glass burettes CH^ , COj, N;>, Oj 2 every 6 months
Surface UC-1 glass bail sampler Total solids, DO, BOD, 150 2 times per nc-th
Water DC-3 Cl , Hardness, Fecal
coliform
Groundwater OW-1
11.7.8 Completed Site
As areas are completed they will be maintained as open space. The com-
pleted landfill will be integrated into the surrounding park land and
used for recreation.
According to site operators, there has been no appreciable subsidence to
date. However, erosion has been a problem and completed areas are re-
graded and seeded as needed. The current slopes are approximately 25%
and it is anticipated that after Phase II is completed the gentler slopes
will alleviate the problem of erosion.
*
11.7.9 Costs
Hauling costs are absorbed by the municipalities contributing sludge to
the site. The units are in dollars per wet ton of total solid waste. As
shown, total site cost is $4.98 per wet ton of total solid waste. Total
site cost per dry ton of sludge is $22.64. Other expenses are presented
below.
Capital and operating costs, and total costs are presented below:
" • 11-63
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Total Cost
(V)
Site Capital Costs -(through FY 1978)
Planning and Design $ 190,931 $0.06
Road Construction 1,887,495 0.61
Clearing and Grubbing 92,572 0.03
Excavations & Stockpiles 1,169,278 0.38
Truck Weigh Station 684,455 0.21
Equipment 440,446 0.14
Erosion Control 4 Regrad. 118,141 0.04
Miscellaneous 237,271 0.08
Total Capital Cost To Date $ 4,820,589 $1.55
Site Operating Costs (for FY 1978)
Personnel ' $ 826,992 $1.61
Equipment Rental 614,488 1.20
Equipment Purchase 8,000 0.02
Equip. Fuel, Parts, Tires 44,000 0.08
Supplies and Materials 176,000 0.34
Utilities 35,600 0.07
Water Testing 10,000 0.02
Miscellaneous 47,000 0.09
Total Site Operating Cost $ 1,762,080 $3.43
Total Cost (less hauling) — $4.98
The unit cost for capital expenditures was determined by establishing the
total costs to date and dividing it by the total waste received to date
(3,110,000 wet tons (2,820,000 Mg)). Similarly, the operating costs for
FY78 were derived by estimating the annual operating expenditures and
dividing these costs by the amount of waste anticipated (513,720 wet tons
(466,000 Mg)). Operating costs for FY77, for comparison, were
$1,508,118.83 and the total tonnage received was 528,207 (480,000 Mg);
resulting in a unit cost of $2.86.
11-64 *U"S GOVERNMENTPI"NTINGOfFICE 1978—760-2V6/1
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