&EPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
EPA/625/R-95/001
September 1995
Process Design Manual
Land Application of
Sewage Sludge and
Domestic Septage
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EPA/625/R-95/001
September 1995
Process Design Manual
Land Application of Sewage Sludge and
Domestic Septage
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Center for Environmental Research Information
Cincinnati, Ohio
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Notice
This document has been reviewed in accordance with the U.S. Environmental Protection Agency's
peer and administrative review policies and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
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Contents
Page
Chapter 1 Introduction
1.1 Overview 1
1.2 Sewage Sludge Regulations 1
1.3 Objectives of Manual 2
1.4 Scope of Manual 3
Chapter 2 Overview of Sewage Sludge Land Application Practices
2.1 Introduction 5
2.2 Application to Agricultural Lands 5
2.2.1 Purpose and Definition 5
2.2.2 Advantages of Agricultural Land Application 5
2.2.3 Limitations of Agricultural Land Application 7
2.3 Application to Forest Lands 7
2.3.1 Purpose and Definition 7
2.3.2 Advantages of Forest Land Application 7
2.3.3 Limitations of Forest Land Application 8
2.4 Land Application at Reclamation Sites 8
2.4.1 Purpose and Definition 8
2.4.2 Advantages of Land Application at Reclamation Sites 9
2.4.3 Limitations of Land Application at Reclamation Sites 9
2.5 Land Application at Public Contact Sites, Lawns, and Home Gardens 9
2.5.1 Purpose and Definition 9
2.5.2 Advantages of Land Application at Public Contact Sites, Lawns, and
Home Gardens 9
2.5.3 Limitations of Land Application at Public Contact Sites, Lawns, and Home
Gardens 10
2.6 References 10
Chapter 3 Overview of the Part 503 Regulatory Requirements for Land Application of
Sewage Sludge
3.1 General 11
3.2 Pollutant Limits 11
3.2.1 Ceiling Concentration Limits 12
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3.2.2 Pollutant Concentration Limits 13
3.2.3 Cumulative Pollutant Loading Rates (CPLRs) 13
3.2.4 Annual Pollutant Loading Rates (APLRs) 14
3.2.5 Why Organic Pollutants Were Not Included in Part 503 14
3.3 Management Practices 14
3.4 Operational Standards for Pathogens and Vector Attraction Reduction 15
3.4.1 Pathogen Reduction Requirements 15
3.4.2 Vector Attraction Reduction Requirements 20
3.5 Frequency of Monitoring 22
3.6 Recordkeeping and Reporting 22
3.7 Sewage Sludge Quality and the Part 503 Requirements 22
3.7.1 Exceptional Quality (EQ) Sewage Sludge 22
3.7.2 Pollutant Concentration (PC) Sewage Sludge 24
3.7.3 Cumulative Pollutant Loading Rate (CPLR) Sewage Sludge 24
3.7.4 Annual Pollutant Loading Rate (APLR) Sewage Sludge 24
3.8 References 26
Chapter 4 Characteristics of Sewage Sludge
4.1 Introduction 27
4.2 Sewage Sludge Quantity 27
4.3 Total Solids Content 29
4.4 Volatile Solids Content 29
4.5 pH 29
4.6 Organic Matter 29
4.7 Pathogens 31
4.8 Nutrients 32
4.8.1 Nitrogen 32
4.8.2 Phosphorous, Potassium, and Other Nutrients 33
4.9 Metals 33
4.10 Organic Chemicals 34
4.11 Hazardous Pollutants (If Any) 34
4.12 Types of Sewage Sludge 35
4.12.1 Primary Sewage Sludge 35
4.12.2 Secondary Sewage Sludge 35
4.12.3 Tertiary Sewage Sludge 35
4.12.4 Domestic Septage 35
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4.13 Effects of Wastewater and Sludge Treatment Processes on Sewage Sludge
Characteristics 35
4.14 Effects of Pretreatment and Pollution Prevention Programs on Sewage Sludge
Characteristics 37
4.15 References 37
Chapter 5 Site Evaluation and Selection Process
5.1 General 39
5.2 Part 503 Requirements 39
5.2.1 Protection of Surface Water and Wetlands 39
5.2.2 Protection of Threatened and Endangered Species 40
5.2.3 Site Restrictions 40
5.3 Planning and Selection Process 41
5.4 Preliminary Planning 41
5.4.1 Institutional and Regulatory Framework 41
5.4.2 Public Participation 41
5.4.3 Preliminary Land Area Requirements 41
5.4.4 Sewage Sludge Transport Assessment 41
5.5 Phase I Site Evaluation and Site Screening 43
5.5.1 Existing Information Sources 43
5.5.2 Land Use and Availability 44
5.5.3 Physical Characteristics of Potential Sites 46
5.5.4 Site Screening 49
5.6 Phase II Site Evaluation: Field Investigation 49
5.7 Selection of Land Application Practice 50
5.8 Final Site Selection 50
5.8.1 Preliminary Cost Analysis 50
5.8.2 Final Site Selection 50
5.9 Site Selection Example 53
5.9.1 City Characteristics 53
5.9.2 Sewage Sludge and Soil Characteristics 53
5.9.3 Regulations Considered 53
5.9.4 Public Acceptance 54
5.9.5 Preliminary Feasibility Assessment 54
5.9.6 Estimate Land Area Required 54
5.9.7 Eliminate Unsuitable Areas 54
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5.9.8 Identify Suitable Areas 55
5.9.9 Phase II Site Survey and Field Investigation 56
5.9.10 Cost Analysis 56
5.9.11 Final Site Selection 56
5.10 References 56
Chapter 6 Phase II Site Evaluation
6.1 General 57
6.2 Preliminary Field Site Survey 57
6.3 Site-Specific Field Investigations 58
6.3.1 Base Map Preparation 58
6.3.2 Field Checking of Surface Features and Marking Buffer Zones on
the Base Map 58
6.3.3 Identifying Topographic Limitations 59
6.3.4 Field Soil Survey 59
6.3.5 Delineation of Floodplains and Wetlands 60
6.3.6 Site Hydrogeology 60
6.4 Soil Sampling and Analysis to Determine Agronomic Rates 61
6.4.1 Part 503 Definition of Agronomic Rate 61
6.4.2 Soil Sampling 61
6.5 Special Considerations for Reclamation Sites 61
6.5.1 Sampling and Analysis of Disturbed Soils 62
6.6 References 62
Chapter 7 Process Design for Agricultural Land Application Sites
7.1 General 63
7.2 Regulatory Requirements and Other Considerations 63
7.2.1 Nitrogen and Other Nutrients 63
7.2.2 Soil pH and Requirements for pH Adjustment 64
7.2.3 Special Considerations for Arid Lands 65
7.3 Application Methods and Scheduling 65
7.3.1 Application Methods 65
7.3.2 Scheduling 67
7.3.3 Storage 68
7.4 Determining Sewage Sludge Application Rates for Agricultural Sites 68
7.4.1 Part 503 Agronomic Rate for N and Pollutant Limits for Metals 68
7.4.2 Crop Selection and Nutrient Requirements 69
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7.4.3 Calculating Residual N, P, and K 69
7.4.4 Calculation of Annual Application Rates 72
7.4.5 Calculation of Supplemental N, P, and K Fertilizer 81
7.4.6 Use of Computer Models To Assist in Determining Agronomic Rates 81
7.5 Design Example of Sewage Sludge Application Rate Calculations 82
7.5.1 Calculation of Agronomic N Rate for Each Field 82
7.5.2 Calculation of Long-Term Pollutant Loadings and Maximum Sewage
Sludge Quantities 83
7.5.3 Calculation of Agronomic P Rate for Each Field 84
7.5.4 Calculation of Supplemental K Fertilizer To Meet Crop Nutrient Requirements . . 90
7.5.5 Additional Considerations for Land Application Program Planning 91
7.6 References 91
Chapter 8 Process Design for Forest Land Application Sites
8.1 General 95
8.2 Regulatory Requirements and Other Considerations 95
8.2.1 Pathogens 95
8.2.2 Nitrogen Dynamics 96
8.3 Effect of Sewage Sludge Applications on Tree Growth and Wood Properties 96
8.3.1 Seedling Survival 96
8.3.2 Growth Response 96
8.3.3 Wood Quality 96
8.4 Effect of Sewage Sludge Application on Forest Ecosystems 96
8.5 Forest Application Opportunities 97
8.5.1 Forest Stand Types 97
8.5.2 Christmas Tree Plantations 99
8.6 Equipment for Sewage Sludge Application at Forest Sites 99
8.6.1 Transfer Equipment 99
8.6.2 Application Equipment 99
8.7 Scheduling 100
8.8 Determining Sewage Sludge Application Rates for Forest Sites 100
8.8.1 General 100
8.8.2 Nitrogen Uptake and Dynamics in Forests 100
8.8.3 Calculation Based on Nitrogen for a Given Year 103
8.8.4 Calculation of Sewage Sludge Application Rates for First and Subsequent
Years 104
8.8.5 Calculation Based on Part 503 Pollutant Limits for Metals 104
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8.9 Design Example of Sewage Sludge Application at Forest Sites 104
8.9.1 Sewage Sludge Quantity and Quality Assumptions 104
8.9.2 Site Selection 104
8.9.3 Determining the Sewage Sludge Application Rate Based on Nitrogen 105
8.9.4 Site Capacity Based on Nitrogen 106
8.10 References 107
Chapter 9 Process Design for Land Application at Reclamation Sites
9.1 General 109
9.2 Consideration of Post-Sewage Sludge Application Land Use 110
9.2.1 Mining Regulations 110
9.3 Nutrients, Soil pH, and Climate Considerations 112
9.3.1 Nutrients 112
9.3.2 Soil pH and pH Adjustment 113
9.3.3 Factors Affecting Crop Yields at Reclamation Sites 113
9.3.4 Special Considerations for Arid Lands 113
9.4 Vegetation Selection 113
9.4.1 General 113
9.4.2 Seeding and Mulching 118
9.5 Sewage Sludge Application Methods 118
9.5.1 Transportation 118
9.5.2 Site Preparation Prior to Sewage Sludge Application 119
9.5.3 Methods of Application 119
9.5.4 Storage 119
9.6 Scheduling 119
9.7 Determining Sewage Sludge Application Rates at Reclamation Sites 120
9.7.1 General Information 120
9.7.2 Approach for Determining a Single, Large Application of Sewage Sludge at a
Reclamation Site 120
9.7.3 Design Example for a Single, Large Sewage Sludge Application at a
Reclamation Site 121
9.8 References 122
Chapter 10 Land Application at Public Contact Sites, Lawns, and Home Gardens
10.1 General 125
10.2 Part 503 Requirements 125
10.3 Marketing of Sewage Sludge 125
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10.3.1 Developing Product Demand 126
10.3.2 Marketing Cost Considerations 126
10.4 References 127
Chapter 11 Land Application of Domestic Septage
11.1 General 129
11.1.1 Definition of Domestic Septage 129
11.1.2 Domestic Septage Versus Industrial/Commercial Septage 130
11.2 Regulatory Requirements for Land Application of Domestic Septage 130
11.2.1 Determining Annual Application Rates for Domestic Septage at Agricultural
Land, Forests, or Reclamation Sites 130
11.2.2 Pathogen Reduction Requirements 131
11.2.3 Vector Attraction Reduction Requirements 131
11.2.4 Certification Requirements for Pathogen and Vector Attraction Reduction 132
11.2.5 Restrictions on Crop Harvesting, Animal Grazing, and Site Access 133
11.2.6 Recordkeeping and Reporting 133
11.2.7 Part 503 Required Management Practices 134
11.2.8 State Requirements for Domestic Septage 134
11.3 Adjusting the pH of Domestic Septage 134
11.3.1 Sampling for pH 135
11.4 Methods of Application 136
11.5 Operation and Maintenance at Land Application Sites Using Domestic Septage 137
11.6 References 138
Chapter 12 Public Participation
12.1 Introduction 139
12.2 Objectives 139
12.3 Implementation of a Public Participation Program 139
12.3.1 Initial Planning Stage 140
12.3.2 Site Selection Stage 143
12.3.3 Site Design Stage 143
12.3.4 Site Preparation and Operation Stage 144
12.4 Special Considerations 144
12.4.1 Agricultural Sites 144
12.4.2 Forest Sites 145
12.4.3 Reclamation Sites 145
12.5 References 145
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Chapter 13 Monitoring and Sampling
13.1 Overview 147
13.2 Sewage Sludge Monitoring and Sampling 147
13.2.1 Sampling Location 147
13.2.2 Frequency of Monitoring 149
13.2.3 Sample Collection 150
13.2.4 Analytical Methods 150
13.3 Soil Monitoring and Sampling 150
13.3.1 Sampling Location and Frequency 152
13.3.2 Number of Samples 152
13.3.3 Sample Collection 152
13.3.4 Analytical Methods 153
13.4 Surface-Water and Ground-Water Monitoring 154
13.4.1 Surface-Water Monitoring 154
13.4.2 Ground-Water Monitoring 154
13.5 Vegetation Monitoring 154
13.6 Monitoring and Sampling at Reclamation Sites 154
13.6.1 General 154
13.6.2 Disturbed Soil Sampling Procedures 154
13.6.3 Suggested Monitoring Program 155
13.7 References 156
Chapter 14 General Design Considerations
14.1 Introduction 157
14.2 Transportation of Sewage Sludge 157
14.2.1 Transport Modes 157
14.2.2 Vehicle Transport 157
14.2.3 Pipeline Transport 163
14.2.4 Other Transport Methods 167
14.3 Storage of Sewage Sludge 168
14.3.1 Storage Requirements 168
14.3.2 Storage Capacity 168
14.3.3 Location of Storage 170
14.3.4 Storage Design 170
14.4 Land Application Methods 171
14.4.1 Overview 171
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14.4.2 Application of Liquid Sewage Sludge 171
14.4.3 Application of Dewatered Sewage Sludge 175
14.5 Site Preparation 177
14.5.1 General 177
14.5.2 Protection of Ground Water and Surface Water Quality 177
14.5.3 Grading 178
14.5.4 Erosion Control 178
14.6 Design of Supporting Facilities 178
14.6.1 Access Roads 178
14.6.2 Public Access: Site Fencing and Security 178
14.6.3 Equipment and Personnel Buildings 179
14.6.4 Lighting and Other Utilities 179
14.7 References 179
Chapter 15 Management, Operational Considerations, and Recordkeeping and Reporting
15.1 Sewage Sludge Management Plans 181
15.2 Part 503 Requirements Affecting Land Application Site Operation 181
15.3 Nuisance Issues 181
15.3.1 Odor 183
15.3.2 Spillage 183
15.3.3 Mud 183
15.3.4 Dust 183
15.3.5 Noise 184
15.3.6 Road Maintenance 184
15.3.7 Selection of Haul Routes 184
15.4 Safety Concerns 184
15.4.1 Training 184
15.5 Health Concerns 185
15.5.1 General 185
15.5.2 Personnel Health Safeguards 185
15.6 Recordkeeping and Reporting 185
15.6.1 General 185
15.6.2 Part 503 Recordkeeping Requirements for Preparers of Sewage Sludge 185
15.6.3 Part 503 Requirements for Appliers of Sewage Sludge 192
15.6.4 Notification Requirements for Preparers and Appliers of Sewage Sludge 192
15.6.5 Notice of Interstate Transport 194
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15.6.6 Notification by Appliers 194
15.6.7 Annual Reports 194
15.7 References 195
Chapter 16 Cost Estimate Guidance for Land Application Systems
16.1 Introduction 197
16.1.1 Information Needed Prior to Using Cost Algorithms 197
16.1.2 Economic Variables 197
16.1.3 Total Base Capital Cost Estimates 198
16.1.4 Total Annual O&M Cost Estimates 198
16.1.5 Calculating Cost Per Dry Ton 198
16.2 Agricultural Land Application 198
16.2.1 General Information and Assumptions Made 198
16.2.2 Process Design and Cost Calculations 199
16.3 Application to Forest Lands 203
16.3.1 General Information and Assumptions Made 203
16.3.2 Process Design and Cost Calculations 203
16.4 Land Application at Reclamation Sites 207
16.4.1 General Information and Assumptions Made 207
16.4.2 Process Design and Cost Calculations 207
16.5 Transportation of Sewage Sludge 211
16.5.1 Truck Hauling of Liquid Sewage Sludge 211
16.5.2 Truck Hauling of Dewatered Sewage Sludge 214
16.5.3 Long-Distance Pipeline Transport of Liquid Sewage Sludge 217
16.6 Example of Preliminary Cost Estimation for Agricultural Land Application to
Cropland 220
16.6.1 Process Design and Cost Calculations 220
16.7 References 223
Appendix A Case Studies 225
Appendix B Federal Sewage Sludge Contacts 283
Appendix C Permit Application Requirements 285
Appendix D Conversion Factors 287
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Figures
Figure Page
1-1 Overview of the Part 503 rule's land application requirements 2
1-2 Suggested sequence for manual use 4
4-1 Generation, treatment, use, and disposal of sewage sludge and domestic septage 28
5-1 Simplified planning steps for a sewage sludge land application system 40
5-2 Institutional framework 42
5-3 Planning, site selection, and land application practice selection sequence 51
5-4 General area map with concentric rings 54
5-5 General soil map showing area selected for sewage sludge land application 54
5-6 Detailed soil survey map of potential site for sewage sludge land application 56
7-1 Determining mineralized PAN from previous sludge applications 75
7-2 Determining agronomic N rate 77
7-3 Worksheet 1 calculations to determine residual N credits for previous sewage sludge applications... 85
7-4 Calculation of the agronomic N rate for the wheat field 86
7-5 Calculation of the agronomic N rate for the corn field 88
11-1 Part 503 pathogen reduction Alternative 1 for domestic septage (without additional treatment)
applied to agricultural land, forests, or reclamation sites 132
11-2 Part 503 pathogen reduction Alternative 2 for domestic septage (with pH treatment) applied to
agricultural land, forests, or reclamation sites 132
11-3 Part 503 vector attraction reduction options for domestic septage applied to agricultural land,
forests, or reclamation sites 133
11-4 Certification of pathogen reduction and vector attraction requirements 133
11-5 Part 503 5-year recordkeeping requirements 133
11-6 Procedure for lime-stabilizing domestic septage within the pumper truck 136
11-7 Subsurface soil injection 136
14-1 Examples of sewage sludge transportation modes to land application sites 158
14-2a A6,500-gallon liquid sludge tank truck 158
14-2b A3,300-gallon liquid sludge tank truck with 2,000-gallon pup trailer 158
14-2c A 25-cubic-yard dewatered sludge haul truck 159
14-2d A 12-cubic-yard dewatered sludge spreader vehicle 159
14-3 Hydraulic characteristics of sludge solids 164
14-4 Storage days required as estimated from the use of the EPA-1 computer program for
wastewater-to-land systems 169
14-5 Example of mass flow diagram using cumulative generation and cumulative sludge
application to estimate storage requirement 170
14-6 Splash plates on back of tanker truck 172
14-7 Slotted T-bar on back of tanker truck 172
14-8 Tank truck with side spray nozzle for liquid sludge surface application 172
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Figures
Figure Page
14-9 Tank truck with liquid sludge tillage injectors 174
14-10 Tank truck with liquid sludge grassland injectors 174
14-11 Tractor-pulled liquid sludge subsurface injection unit connected to delivery hose 174
14-12a Tank wagon with sweep shovel injectors 175
14-12b Sweep shovel injectors with covering spoons mounted on tank wagon 175
14-13 Center pivot spray application system 176
14-14 Traveling gun sludge sprayer 176
14-15 Diagram of liquid sludge spreading system in forest land utilizing temporary storage ponds 176
14-16 A 7.2-cubic-yard dewatered sludge spreader 177
14-17 Large dewatered sludge spreader 177
14-18 Example of a disk tiller 177
14-19 Example of a disk plow 177
15-1 Sludge Management Plan 182
15-2 Restrictions for the harvesting of crops and turf, grazing of animals, and public access on sites
where Class B biosolids are applied 182
15-3 Examples of crops impacted by site restrictions for Class B sewage sludge 182
15-4 Required records for preparers of sewage sludge to document sampling and analysis 187
15-5 Certification statement required for recordkeeping 187
15-6 Pathogen reduction alternative 3—analysis and operation 189
15-7 Notice and necessary information 193
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Tables
Table Page
1-1 Quantity of Sewage Sludge Generated Annually by Use or Disposal Practice 1
2-1 Summary of Typical Characteristics of Sewage Sludge Land Application Practices 6
3-1 Types of Sludge, Septage, and Other Wastewater Solids Excluded From Coverage Under Part 503 . 12
3-2 Definitions of Terms Under the Part 503 Rule 12
3-3 Who Must Apply for a Permit? 13
3-4 Part 503 Land Application Pollutant Limits for Sewage Sludge 13
3-5 Part 503 Land Application Management Practices 14
3-6 Summary of Class A and Class B Pathogen Alternatives 15
3-7 Pathogen Requirements for All Class A Alternatives 16
3-8 The Four Time-Temperature Regimes for Pathogen Reduction Under Class A, Alternative 1 16
3-9 Processes To Further Reduce Pathogens Listed in the Part 503 Rule 17
3-10 A Partial List of Processes Recommended as Equivalent to PFRP Under Part 257 18
3-11 Restrictions for the Harvesting of Crops and Turf, Grazing of Animals, and Public Access on Sites
Where Class B Sewage Sludge is Land Applied 18
3-12 Processes to Significantly Reduce Pathogens (PSRPs) Listed in Part 503 19
3-13 Selected Processes Recommended as Equivalent to PSRP Under Part 2571 19
3-14 Summary of Vector Attraction Reduction Requirements for Land Application of Sewage Sludge
Under Part 503 20
3-15 Frequency of Monitoring for Pollutants, Pathogen Densities, and Vector Attraction Reduction 23
3-16 Summary of Part 503 Requirements for Different Types of Sewage Sludge 23
3-17 Part 503 Land Application General Requirements 25
3-18 Procedure to Determine the Annual Whole Sludge Application Rate for Sewage Sludge Sold or
Given Away in a Bag or Other Container for Application to Land 26
4-1 Effects of Sewage Sludge Treatment Processes on Land Application Practices 30
4-2 Principal Pathogens of Concern in Municipal Wastewater and Sewage Sludge 31
4-3 Typical Pathogen Levels in Unstabilized and Anaerobically Digested Liquid Sludges 31
4-4 Nutrient Levels Identified in Sewage Sludge 32
4-5 Mean Concentrations of Metals in Sewage Sludge Compared to Part 503
Ceiling Concentration Limits 33
4-6 Analytical Classification and Limits for TCLP Constituents 34
4-7 Chemical and Physical Characteristics of Domestic Septage 35
4-8 Nutrient Levels in Sewage Sludge From Different Treatment Processes 36
5-1 Preliminary Estimates of Sewage Sludge Applications (Dry Weight) for Different Types of Land 43
5-2 Sewage Sludge Solids Content and Handling Characteristics 43
5-3 Transport Modes for Sewage Sludge 43
5-4 Auxiliary Facilities for Sewage Sludge Transport 44
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5-5 Evaluation of Sewage Sludge Transport Modes 44
5-6 Suggested Provisions of Contracts Between Sewage Sludge Preparer, Sludge Applier,
and Private Landowners 47
5-7 Potentially Unsuitable Areas for Sewage Sludge Application 47
5-8 Recommended Slope Limitations for Land Application of Sewage Sludge 47
5-9 Soil Limitations for Sewage Sludge Application to Agricultural Land at Nitrogen Fertilizer
Rates in Wisconsin 48
5-10 Recommended Depth to Ground Water 48
5-11 Potential Impacts of Climatic Regions on Land Application of Sewage Sludge) 49
5-12 Example Design Features Checklist/Comparison of Candidate Land Application Practices 52
5-13 Relative Ranking for Forest Sites for Sewage Sludge Application 53
5-14 Cost Factors To Be Considered During Site Selection 53
5-15 Ranking of Soil Types for Sewage Sludge Application 55
6-1 Basic Site-Specific Information Needed for Land Application of Sewage Sludge 57
6-2 Sample Form for Preliminary Field Site Survey 58
6-3 Types of Data Available on SCS Soil Series Description and Interpretation Sheets 59
7-1 Summary of Research on Sewage Sludge Application to Rangeland 66
7-2 General Guide to Months Available for Sewage Sludge Application for Different Crops in
North Central States 67
7-3 Representative Fertilizer Recommendations for Corn and Grain Sorghum in the Midwest 70
7-4 Representative Fertilizer Recommendations for Soybeans in the Midwest 70
7-5 Representative Fertilizer Recommendations for Small Grains in the Midwest 71
7-6 Representative Fertilizer Recommendations for Forages in the Midwest 71
7-7 Estimated Mineralization Rates (K^) for Different Sewage Sludges 72
7-8 Volatilization Losses of NH4-N as NH3 74
7-9 Part 503 Cumulative Pollutant Loading Rate (CLPR) Limits 80
7-10 Amounts of Pollutants Added by Sewage Sludge in Design Example 84
8-1 Sewage Sludge Application to Recently Cleared Forest Sites 97
8-2 Sewage Sludge Application to Young Forest Plantations (Over 2 Years Old) 98
8-3 Sewage Sludge Application to Closed Established Forest (Over 10 Years Old) 98
8-4 Comparison of Different Application Systems for Forest Sites 99
8-5 Monthly Application Schedule for a Design in the Pacific Northwest 100
8-6 Estimated Annual Nitrogen Removal by Forest Types 101
8-7 Ranges of Values and Suggested Design Values for Nitrogen Transformations and
Losses From Sewage Sludge Applied to Forest Environments 101
8-8 Example First-year Application Rate for Sewage Sludge Based on Available Nitrogen
for Two Different Types of Douglas-fir Stands 103
8-9 N Requirements for Sewage Sludge Application to Hybrid Poplar and Established Douglas-fir
Plantations 105
8-10 Sewage Sludge Application Rates to Meet N Requirements at Forest Sites 106
8-11 Maximum Annual Sewage Sludge Application Based on N Requirements 106
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9-1 Hectares Under Permit for Surface, Underground, and Other Mining Operations
From 1977 to 1986 109
9-2 Number of Hectares Reclaimed With Bonds Released During 1977 to 1986 109
9-3 Recent Land Reclamation Projects With Municipal Sludge 111
9-4 Humid Eastern Region Vegetation 114
9-5 Drier Mid-West and Western Region Vegetation 115
9-6 Western Great Lakes Region 115
9-7 Northern and Central Prairies 115
9-8 Northern Great Plains 115
9-9 Southern Great Plains 116
9-10 Southern Plains 116
9-11 Southern Plateaus 116
9-12 Intermountain Desertic Basins 116
9-13 Desert Southwest 116
9-14 California Valleys 117
9-15 Some Sucessful Plant Species and Species Mixtures Used in Various Sludge
Reclamation Projects 117
10-1 Percent of POTWs Selling Sewage Sludge and Mean Price of Sewage Sludge Sold 127
11-1 Characteristics of Domestic Septage: Conventional Parameters 129
11-2 Characteristics of Domestic Septage: Metals and Organics 130
11-3 Typical Crop Nitrogen Requirements and Corresponding Domestic Septage Application Rates 131
11-4 Summary of Domestic Septage Stabilization Options 135
11-5 Summary of Land Application Methods for Domestic Septage 137
12-1 Relative Effectiveness of Public Participation Techniques 140
12-2 Potential Advisory Committee Members 140
13-1 Monitoring Considerations for Part 503 Requirements 148
13-2 Sampling Points for Sewage Sludge 149
13-3 Sewage Sludge Sample Containers, Preservation, and Storage 151
13-4 Analytical Methods for Sewage Sludge Sampling 151
13-5 Potential Soil Surface Layer and Subsurface Parameters of Interest 152
13-6 Suggested Procedures for Sampling Diagnostic Tissue of Crops 155
14-1 Truck Operation Summary, Liquid Sludge 160
14-2 Truck Operation Summary, Dewatered Sludge 161
14-3 Projected Monthly Sludge Distribution for Agricultural Sludge Utilization Program,
Madison, Wisconsin 162
14-4 Use of Sewage Sludge Pumps 166
14-5 Surface Application Methods for Liquid Sewage Sludge 172
14-6 Subsurface Application Methods for Liquid Sewage Sludge 174
14-7 Methods and Equipment for Application of Dewatered Semisolid and Solid Sludges 176
15-1 Part 503 Recordkeeping and Reporting Requirements 186
15-2 Recordkeeping Recommendations for Class A Pathogen Reduction Alternatives 188
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15-3 Recordkeeping Requirements for Class B Pathogen Reduction Alternatives 190
16-1 Typical Days Per Year of Food Chain Crop Sludge Application 199
16-2 Capacity and Number of Onsite Mobile Sludge Application Vehicles Required 200
16-3 Vehicle Load, Unload, and Onsite Travel Time 200
16-4 Vehicle Sludge Handling Capacity 200
16-5 Gallons of Fuel Per Hour for Various Capacity Sludge Application Vehicles 201
16-6 Cost of Onsite Mobile Sludge Application Vehicles 202
16-7 Hourly Maintenance Cost for Various Capacities of Sludge Application Vehicles 202
16-8 Capacity and Number of Onsite Mobile Sludge Application Vehicles Required 204
16-9 Vehicle Load, Unload, and Onsite Travel Time 204
16-10 Vehicle Sludge Handling Capacity 204
16-11 Gallons of Fuel Per Hour for Various Capacity Sludge Application Vehicles 205
16-12 Cost of On-Site Mobile Sludge Application Vehicles (1994) 206
16-13 Hourly Maintenance Cost for Various Capacities of Forest Land Sludge Application Vehicles 207
16-14 Typical Truck Unloading Time as a Function of Type of Land Application Used 211
16-15 Typical Days Per Year of Sludge Hauling as a Function of Types of Application Used and
Geographical Region 212
16-16 Number of Vehicles and Capacity of Each Truck 212
16-17 Fuel Use Capacities for Different Sized Trucks 212
16-18 Cost of Tanker Truck 212
16-19 Loading Area Costs Based on Sludge Volume 213
16-20 Vehicle Maintenance Cost Factors 213
16-21 Capacity and Number of Haul Vehicles 214
16-22 Fuel Usage Values for Different Sized Trucks 215
16-23 Costs for Different Sized Trucks 215
16-24 Loading Area Costs 216
16-25 Vehicle Maintenance Cost Factors 216
16-26 Factors for Various Sludge Concentrations and Two Types of Sludge 217
16-27 Head Available from Each Pumping Station 218
16-28 Annual Labor Per Pump Station 218
16-29 Pipeline Cost 219
16-30 Annual Cost of Pumping Station Parts and Supplies 220
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A cknowledgments
Three groups of participants were involved in the preparation of this manual: (1) the writers, (2) the
technical directors, and (3) the technical reviewers. (Note: This document was originally published
by EPA in 1983; this edition represents a significantly updated revision.) The contractor for this
project was Eastern Research Group, Inc. (ERG), Lexington, Massachusetts, with senior ERG staff
serving as primary writers. Contributing writers provided key information on land application at forest
sites and agricultural sites. The technical advisor was an environmental engineering consultant with
expertise in sewage sludge land application systems, who provided invaluable technical knowledge
throughout the project. Technical direction was provided by U.S. Environmental Protection Agency
(EPA) personnel from the Center for Environmental Research Information (CERI) in Cincinnati,
Ohio, and the Office of Water in Washington, DC. The technical reviewers were experts in sewage
sludge land application, and included university professors/researchers, consultants, and govern-
ment officials. Each reviewer provided a significant critique of the manual. The people involved in
this project are listed below.
Manual Preparation
Eastern Research Group, Inc. (ERG)
Writers: Linda Stein, ERG
Russell Boulding, ERG
Jenny Helmick, ERG
Paula Murphy, ERG
Contributing
Writers: Charles Henry, University of Washington
Lee Jacobs, Michigan State University
Technical Advisor: Sherwood Reed, Environmental Engineering Consultants
Technical Direction
Project Director: James E. Smith, CERI, EPA, Cincinnati, OH
Technical Director: Robert Southworth, Office of Water, EPA, Washington, DC
Technical Review:
William Sopper, Pennsylvania State University, State College, PA
Robert Brobst, U.S. EPA Region VIM, Denver, CO
Robert Southworth, Office of Water, EPA, Washington, DC
Lee Jacobs, Michigan State University, East Lansing, Ml
Charles Henry, University of Washington, Eatonville, WA
Ronald Crites, Nolte and Associates, Inc., Sacramento, CA
XIX
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Chapter 1
Introduction
1.1 Overview
Land application of sewage sludge1 generated by domes-
tic sewage treatment is performed in an environmentally
safe and cost-effective manner in many communities.
Land application involves taking advantage of the fertilizing
and soil conditioning properties of sewage sludge by
spreading the sewage sludge on the soil surface, incorpo-
rating or injecting the sewage sludge into soil, or spraying
the sewage sludge. Because sewage sludge disposal
practices (e.g., landfilling) are becoming less available and
more costly, and because of the increasing desire to bene-
ficially reuse waste residuals whenever possible, land ap-
plication is increasingly chosen as a sewage sludge use
or disposal practice.
Approximately 33 percent of the 5.4 million dry metric
tons of sewage sludge generated annually in the United
States at publicly owned treatment works (POTWs) is
land applied, as shown in Table 1-1. Of the sewage
sludge that is land applied, approximately 67 percent is
land applied on agricultural lands, 3 percent on forest
lands, approximately 9 percent on reclamation sites,
and 9 percent on public contact sites; 12 percent is sold
or given away in a bag or other container for application
to the land (Federal Register, Vol. 58, No. 32, February
19, 1993). In addition, approximately 8.6 billion gallons
of domestic septage is generated annually.
Land application of sewage sludge has been practiced
in many countries for centuries so that the nutrients
(e.g., nitrogen, phosphorus) and organic matter in sew-
age sludge can be beneficially used to grow crops or
other vegetation. Over the years, land application has
been increasingly managed to protect human health
and the environment from various potentially harmful
constituents typically found in sewage sludge, such
as bacteria, viruses, and other pathogens; metals
(e.g., cadmium and lead); toxic organic chemicals (e.g.,
PCBs); and nutrients (e.g., nitrogen as nitrate). Manage-
The term "biosolids" has recently gained popularity as a synonym
for sewage sludge because it perhaps fosters "reuse" potential bet-
ter than the term "sewage sludge." While this premise may be true,
this manual does not use the term "biosolids" because the term is
not defined consistently at this time and because the federal Part
503 regulation uses the term "sewage sludge."
ment of the land application of sewage sludge has in-
cluded regulatory measures; voluntary and mandatory
pretreatment of wastewater and/or sludge by industry to
improve quality (e.g., lower pollutant levels); and use of
good management practices at land application sites
(e.g., buffer zones, slope restrictions).
1.2 Sewage Sludge Regulations
In 1993, the U.S. Environmental Protection Agency
(EPA) promulgated 40 CFR Part 503 to address the
Clean Water Act's (CWA) requirement that EPA develop
a regulation for the use or disposal of sewage sludge.
The CWA required that this regulation protect public
health and the environment from any reasonably antici-
pated adverse effects of pollutants in sewage sludge.
The elements of the Part 503 land application standard
are illustrated in Figure 1-1. The pollutant limits in the
Part 503 rule were based on in-depth risk assessments
Table 1-1. Quantity of Sewage Sludge Generated Annually by
Use or Disposal Practice (Federal Register,
February 19, 1993)
POTWs Using a
Use/Disposal
Practice
Use/Disposal
Practice
Land application
Incineration
Co-disposal: Landfill
Surface disposal
Unknown:
Ocean disposal13
Other
Transfer
Number
4,657
381
2,991
1,351
133
3,920
25
Percent
of
POTWs
34.6
2.8
22.2
10.0
1.0
29.1
0.2
Quantity of
Sewage Sludge
Used or Disposed3
Quantity
(1,000
dmt)
1 ,785.3
864.7
1,818.7
553.7
335.5
0
N/A
Percent
of
Sewage
Sludge
33.3
16.1
33.9
10.3
6.3
0.0
N/A
All POTWs
13,458
100.0
5,357.2
100.0
Numbers may not add up to 100 percent because of rounding.
b The National Sewage Sludge Survey, on which these figures are
based, was conducted before the Ocean Dumping Ban Act of 1988,
which generally prohibited the dumping of sewage sludge into the
ocean after December 31, 1991. Ocean dumping of sewage sludge
ended in June 1992.
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General Requirements
Reporting | _Pollutant Limits
Recordkeepin<
Frequency of
Monitoring
Management
Practices
Operational Standards
Pathogen
and Vector
Attraction
Reduction
Figure 1-1. Overview of the Part 503 rule's land application requirements.
that investigated the effects on human health and the
environment of using or disposing sewage sludge. The
pollutant limits and management practices in Part 503
protect human health and the environment, as required
by the CWA. Another key component of the rule is
the operational standard that requires reduction of
pathogens (i.e., disease-causing organisms) and of vec-
tor attraction (e.g., insects, rodents) using specified op-
erational processes (e.g., treatment), microbiological
monitoring, and physical barriers (e.g., injection or incor-
poration) for sewage sludge to achieve this reduction.
This operational standard, in the judgement of EPA, pro-
tects public health and the environment from pathogens
and vectors. Other parts of the rule (i.e., general require-
ments, frequency of monitoring, recordkeeping, and re-
porting requirements) make the rule self-implementing.
Research has shown that most sewage sludge currently
generated in the United States meets the minimum
pollutant limits and pathogen reduction requirements set
forth in Part 503, and that some sewage sludge already
meets the most stringent Part 503 pollutant limits and
pathogen and vector attraction reduction requirements.
This manual refers to the Part 503 regulation throughout
the document as it relates to the specific topic being
discussed (e.g., site selection, design). In addition, this
manual provides a summary of the Part 503 land appli-
cation requirements (Chapters).
State agencies may have their own rules governing the
use or disposal of sewage sludge or domestic septage.
If this is the case, or if a state has not yet adopted
the federal rule, the generator or preparer of sewage
sludge destined for land application will have to follow
the most restrictive portions of both the federal and state
rules. Users or disposers of sewage sludge or domestic
septage are strongly encouraged to check with the ap-
propriate state sewage sludge coordinator to obtain
information on specific and the most up-to-date state
requirements.
1.3 Objectives of Manual
The information in this manual is intended for use by
municipal wastewater treatment and sewage sludge
management authorities, project planners and design-
ers, regional, state, and local governments concerned
with permitting and enforcement of federal sewage
sludge regulations, and consultants in relevant disci-
plines such as engineering, soil science, and agronomy.
The manual is intended to provide general guidance and
basic information on the planning, design, and operation
of sewage sludge land application projects for one or
more of the following design practices:
• Agricultural land application (crop production, im-
provement of pasture and rangeland).
• Forest land application (increased tree growth).
• Land application at reclamation sites (mine spoils,
construction sites, gravel pits).
• Land application at public contact sites (such as
parks and golf courses), lawns, and home gardens.
This manual reflects state-of-the art design information
for the land application of sewage sludge. Other EPA
manuals that can serve as useful supplements to this
guide include:
• Environmental Regulations and Technology: Control
of Pathogens and Vector Attraction in Sewage
Sludge. 1992. Office of Research and Development.
EPA/625/R-92/013.
• Preparing Sewage Sludge For Land Application Or
Surface Disposal: A Guide for Preparers of Sewage
Sludge on the Monitoring, Record Keeping, and Re-
porting Requirements of the Federal Standards for
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the Use or Disposal of Sewage Sludge, 40 CFR Part
503. 1993. Office of Water. EPA 831 B-93-002.
• A Plain English Guide to the EPA Part 503 Biosolids
Rule. 1994. Office of Wastewater Management.
EPA/832/R-93/003.
• Domestic Septage Regulatory Guidance: A Guide to
the EPA 503 Rule. 1993. Office of Water. EPA 832-
B-92-005.
• Technical Support Document for Land Application of
Sewage Sludge. 1992. Vols. I and II. Office of Water.
EPA 822/R-93-001a. (NTIS No.: PB93-110583 and
PB93-110575).
• Process Design Manual: Sludge Treatment and Dis-
posal. 1979. Office of Research and Development.
EPA/625/1-79/011.
• Process Design Manual for Dewatering Municipal
Wastewater Sludge. 1982. Office of Research and
Development. EPA/625/1-82/014.
References are made throughout this manual to these
and other documents for more detailed information on
specific topics relevant to designing land application
systems. Full citations for all references are provided at
the end of each chapter.
1.4 Scope of Manual
This manual covers both regulatory and non-regulatory
aspects of designing and operating sewage sludge land
application sites. This manual does not discuss the sur-
face disposal of sewage sludge or codisposal of sewage
sludge with municipal solid waste, which is covered in
the Process Design Manual: Surface Disposal of Sew-
age Sludge and Domestic Septage (EPA, 1995, EPA/
625/R-95/002). This manual also does not discuss incin-
eration of sewage sludge, which is discussed in the
Technical Support Document for Incineration of Sewage
Sludge (EPA, 1992, NTIS PB93-110617). In addition,
discussion of industrial sludge, which is regulated by 40
CFR Part 257, is beyond the scope of this manual.
Figure 1-2 presents a suggested sequence to follow
when using this manual, which may be varied according
to user needs. The manual consists of 16 chapters and
4 appendices. The appendices provide case studies,
regional EPA office information, permit requirements,
and measurement conversions.
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Figure 1-2. Suggested sequence for manual use.
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Chapter 2
Overview of Sewage Sludge Land Application Practices
2.1 Introduction
The sewage sludge land application practices listed in
the previous chapter are not mutually exclusive. For
example, land reclamation may involve the planting of
trees on sewage sludge-amended soil, and two or more
practices (e.g., land application at agricultural and forest
sites) can be used in a single sewage sludge manage-
ment program. Table 2-1 summarizes the typical char-
acteristics of the sewage sludge land application
practices covered in this manual.
Each of these practices has advantages and disadvan-
tages in terms of the quality and quantities of sewage
sludge that can be utilized and for application site re-
quirements. This chapter provides an overview of the
land application practices and highlights their advan-
tages and disadvantages. Each practice is then dis-
cussed in greater detail in the subsequent design
chapters. The design chapters present the criteria and
limitations that establish sewage sludge application
rates in detail.
2.2 Application to Agricultural Lands
2.2.1 Purpose and Definition
Agricultural land application of sewage sludge is prac-
ticed in nearly every state, and is especially common in
Colorado, New Jersey, Pennsylvania, Ohio, Illinois,
Michigan, Missouri, Wisconsin, Oregon, and Minnesota.
Hundreds of communities, both large and small, have
developed successful agricultural land application pro-
grams. These programs benefit the municipality gener-
ating the sewage sludge by providing an ongoing,
environmentally acceptable, and cost-effective means
of managing sewage sludge; the participating farmer
also benefits by receiving the nutrients in sewage sludge
for crop production, generally at a lower cost than con-
ventional fertilizers.
Sewage sludge applied to agricultural land must be
applied at a rate that is equal to or less than the "agro-
nomic rate," defined in Part 503 as the rate designed to
provide the amount of nitrogen needed by the crop or
vegetation while minimizing the amount of nitrogen in
the sewage sludge that will pass below the root zone of
the crop or vegetation to the ground water. The amount
of available N (or P) applied to the site is based on that
required by the crop. This amount of N would otherwise
be applied to the site as commercial fertilizer by the
farmer. By limiting N loadings to fertilizer recommenda-
tions, the impact on ground water should be no greater
than in agricultural operations using commercial fertiliz-
ers or manure; ground-water impacts may even be less
because of Part 503's agronomic rate requirement.
Chapter 7 of this manual provides details of agronomic
rate calculations for agricultural sites.
2.2.2 Advantages of Agricultural Land
Application
Sewage sludge contains several plant macronutrients,
principally N and P, and in most cases, varying amounts
of micronutrients such as boron (B), copper (Cu), iron
(Fe), manganese (Mn), molybdenum (Mo), and zinc
(Zn). The exact ratio of these nutrients will not be that of
a well-balanced formulated fertilizer; but the nutrients in
sewage sludge can be combined with nutrients from
other fertilizers to provide the proper amounts of nutri-
ents needed for crop production.
Sewage sludge can also be a valuable soil conditioner.
The addition of organic materials like sewage sludge to
a fine-textured clay soil can help make the soil more
friable and can increase the amount of pore space
available for root growth and the entry of water and air
into the soil. In coarse-textured sandy soils, organic
residues like sewage sludge can increase the water-
holding capacity of the soil and provide chemical sites
for nutrient exchange and adsorption. In some regions
of the country, the water added to the soil during sewage
sludge application also is a valuable resource.
The treatment works generating the sewage sludge can
benefit because in many cases agricultural land appli-
cation is less expensive than alternative methods of
sewage sludge use or disposal. The general public may
benefit from cost savings resulting from agricultural land
application of sewage sludge, and the recycling of nutri-
ents is attractive to citizens concerned with the environ-
ment and resource conservation.
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Table 2-1. Summary of Typical Characteristics of Sewage Sludge Land Application Practices
Characteristics
Agricultural Land
Application3
Forest Land
Application
Land Application at
Reclamation Sites
Application to Public
Contact Sites, Lawns,
and Home Gardens
Application rates
Application frequency
Ownership of
application site(s)
Useful life of application
site(s)
Sewage sludge
transport complexity
and cost
Sewage sludge
scheduling
Application constraints
Sludge nutrients
beneficially recycled
Potential benefits to
existing soil condition
Varies; normal range in
dry weight of 2 to 70
t/ha/yr (1 to 30 T/ac/yr)
depending on type of
crops, sewage sludge
characteristics, etc.
Typical rate is 10 t/ha/yr
(5 T/ac/yr).
Typically repeated
annually, usually
scheduled between
harvesting and planting.
Scheduling can be
complex with large
quantities of sludge.
Usually privately owned
land. Conditions of
application often
covered by a contract
between farmer(s) and
municipality.
Unlimited for sludge
meeting Part 503
pollutant concentration
limits (PCLs, see
Chapter 3); limited by
accumulated metal
loadings from total
sludge applied when
sludge does not meet
PCLs—typically 20-100
or more years"
Can be expensive if
farms are numerous
and long transportation
distances are involved.
Scheduling can be
difficult, because
applications must work
around planting/
harvesting activities and
poor weather conditions.
Usually none when
appropriate application
vehicles are used. May
be limited by cropping
pattern and Part 503
agronomic rate
management practice
requirement.
Yes. Reduces
commercial fertilizer use.
Depends on existing
soil characteristics and
quantity of sludge used.
Varies; normal range in
dry weight of 10 to 220
t/ha/yr (4 to 100 T/ac/yr)
depending on soil, tree
species, sewage sludge
quality, etc. Typical rate
is about 18 t/ha/yr (8
T/ac/yr).b
Usually applied annually
or at 3- to 5-year
intervals.
Usually owned by
private tree-growing firm
or governmental agency
at state/federal level.
Usually limited by
accumulated metal
loadings in total sewage
sludge applied. With
most sewage sludge, a
useful life of 20 to 55
years or more is typical.b
Depends on distance to
forest lands and roads
within site.
Scheduling affected by
climate and maturity of
trees.
Can be difficult if limited
access roads and
uneven terrain. May
involve specially
designed application
equipment. May be
limited by Part 503
agronomic rate
management practice
requirement.
Yes. Reduces or
eliminates commercial
fertilizer use.
Depends on existing
soil characteristics.
Varies; normal range in
dry weight of 7 to 450
t/ha/yr (3 to 200
T/ac/yr). Typical rate is
112 t/ha/yr (50 T/ac/yr).
Usually a one-time
application.
Usually a one-time
application.
Usually owned by
mining firm or
governmental agency at
state/federal level.
Usually a one-time
application that helps
revegetate site.
Cumulative pollutant
limits may not be
reached for 13 to 50 or
more years.b
Depends on distance to
disturbed lands.
Scheduling affected by
climate and availability
of new sites.
Usually none, but may
be complicated by
irregular terrain
common at disturbed
sites.
Yes. Reduces or
eliminates commercial
fertilizer use.
Yes. Allows soil to
support vegetation and
retards erosion.
Varies depending on
end use (e.g., crops,
turf). Typical rate is 18
t/ha/yr (8 T/ac/yr).
Varies depending on
end use.
Usually privately owned;
some public contact
sites (e.g., parks) may
be owned by a
governmental agency.
Varies, possibly 32 or
more years.b
May include conveying
sewage sludge from
wastewater treatment
plant to processing
center, transport of
bulking materials for
composting, and
distribution of the
finished sewage sludge.
Varies depending on
end use.
None; similar to surface
application of solid or
semisolid fertilizers,
lime, or animal manure.
Yes. Reduces
commercial fertilizer use.
Depends on existing
soil characteristics and
quantity of sludge used.
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Table 2-1. Summary of Typical Characteristics of Sewage Sludge Land Application Practices (continued)
Characteristics
Agricultural Land
Application3
Forest Land
Application
Land Application at
Reclamation Sites
Application to Public
Contact Sites, Lawns,
and Home Gardens
Dramatic improvement
in vegetative growth
response
Existing projects using
this practice
Availability of technical
literature pertaining to
this practice
May improve
production; generally
replaces some
commercial fertilizer
nutrients.
Hundreds of large and
small full-scale projects.
Extensive.
Yes. Projects show
large positive impact.
A moderate number of
full-scale and
demonstration projects.
Moderate.
Yes. Projects show
large positive impact.
A moderate number of
full-scale and
demonstration projects.
Moderate.
Depends on existing
soil conditions and
quantities of plant
nutrients normally
applied.
A moderate number of
full-scale and
demonstration projects.
Moderate.
at = metric tonnes, T = English tons
b Estimates of useful site life from EPA's Technical Support Document for Land Application of Sewage Sludge (U.S. EPA, 1992). Site life may
be longer if sludge is not applied every year.
A major advantage of agricultural land application is that
usually the treatment works does not have to purchase
land. The land utilized for sewage sludge application is
kept in production, its value for future uses is not im-
paired, and it remains on the tax rolls. Finally, agricul-
tural land application usually takes place in a relatively
rural setting where the application of sewage sludge is
similar to conventional farming operations, such as
spreading animal manure, and is not likely to become a
public nuisance if properly managed.
2.2.3 Limitations of Agricultural Land
Application
Sewage sludge application rates for agricultural land
application (dry unit weight of sludge applied per unit of
land area) are usually relatively low. Thus, large land
areas may be needed, requiring the cooperation of
many individual land owners. In addition, sewage sludge
transport, as well as application scheduling that is com-
patible with agricultural planting, harvesting, and possi-
ble adverse climatic conditions, will require careful
management. If the farms accepting sewage sludge
are numerous and widespread, an expensive and com-
plicated sewage sludge distribution system may be
required.
2.3 Application to Forest Lands
2.3.1 Purpose and Definition
Except for certain areas in the Great Plains and the
southwest, forested lands are abundant and well distrib-
uted throughout most of the United States. Many treat-
ment works are located in close proximity to forests; in
fact, it is estimated that close to one-third of the land
within standard metropolitan areas is forested. Further-
more, approximately two-thirds of all forest land in the
United States is commercial timberland (Smith and
Evans, 1977). Thus, while currently 3 percent of sewage
sludge that is land applied is applied to forest sites, the
application of sewage sludge to forest soils has the
potential to be a major sewage sludge use practice.
Sewage sludge has been land applied at forest sites in
more than ten states, at least on an experimental, field-
scale level. The most extensive experience with this
practice is in the Pacific Northwest. Seattle, Washington,
and a number of smaller towns apply sewage sludge to
forests on a relatively large scale.
Three categories of forest land may be available for
sewage sludge application:
• Recently cleared land prior to planting
• Newly established plantations (about 3 to 10 years old)
• Established forests
The availability of sites and application considerations
for each type of site listed above (as discussed in Chap-
ter 8) will determine which type of site or combination of
sites is best for a forest land application program.
2.3.2 Advantages of Forest Land Application
Sewage sludge contains nutrients and essential micro-
nutrients often lacking in forest soils. Demonstration
projects have shown greatly accelerated tree growth
resulting from sewage sludge application to both newly
established plantations and established forests. In addi-
tion, sewage sludge contains organic matter that can
improve the condition of forest soils by increasing the
permeability of fine-textured clay soil, or by increasing
the water-holding capacity of sandy soils.
Treatment works located near forest lands may benefit
because forest land application may be less expensive
than other methods of sewage sludge use or disposal.
The general public may benefit from cost savings real-
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ized by the treatment works and commercial tree grow-
ers using the sewage sludge, and the recycling of nutri-
ents in sewage sludge is attractive to environmentally
concerned citizens. Because forests are perennial, the
scheduling of sewage sludge applications is not as com-
plex as it may be for agricultural land application pro-
grams, for which planting and harvesting cycles must be
considered. A final advantage of forest land application
is that the treatment works may not have to pay for
acquiring land. Sewage sludge application to forest soils
is generally performed either annually or at 3- to 5-year
intervals.
2.3.3 Limitations of Forest Land Application
Because sewage sludge application to forest lands is
not as widely practiced as agricultural application, guid-
ance on this practice is more limited. Chapters provides
information on land application at forest sites. The Natu-
ral Resource Conservation Service (formerly the Soil
Conservation Service) and County Land-Grant Univer-
sity Extension agents may be able to assist with pro-
gram design and implementation.
It may be difficult to control public access to sewage
sludge-amended forest lands. The public is accustomed
to free access to forested areas for recreational pur-
poses and may tend to ignore posted signs, fences, etc.
Public access restrictions required in Part 503 are dis-
cussed in Chapter 3. Forest lands generally are consid-
ered to have low potential for public exposure regarding
risks associated with the land application of sewage
sludge.
Access into some forest lands may be difficult for con-
ventional sewage sludge application equipment. Terrain
may be uneven and obstructed. Access roads may have
to be built, or specialized sewage sludge application
equipment used or developed.
2.4 Land Application at Reclamation
Sites
2.4.1 Purpose and Definition
The surface mining of coal, exploration for minerals,
generation of mine spoils from underground mines, and
tailings from mining operations have created over 1.5
million ha (3.7 million ac) of drastically disturbed land.
The properties of these drastically disturbed and mar-
ginal lands vary considerably from site to site. Their
inability to support vegetation is the result of several
factors:
• Lack of nutrients. The soils have low N, P, K, or
micronutrient levels.
• Physical properties. Stony or sandy materials have
poor water-holding capacity and low cation exchange
capacity (CEC). Clayey soils have poor infiltration,
permeability, and drainage.
• Chemical properties. The pH of mine soils, tailings,
and some drastically disturbed soils range from very
acidic to alkaline. Potentially phytotoxic levels of Cu,
Zn, Fe, and salts may be present.
• Organic matter. Little, if any, organic matter is present.
• Biological properties. Soil biological activity is gener-
ally reduced.
• Topography. Many of these lands are characterized
by steep slopes that are subject to excessive erosion.
Historically, reclamation of these lands is accomplished
by grading the surface to slopes that minimize erosion
and facilitate revegetation. In some cases, topsoil is
added. Soil amendments such as lime and fertilizer also
are added, and grass, legumes, or trees are planted.
Although these methods are sometimes successful, nu-
merous failures have occurred, primarily because of the
very poor physical, chemical, or biological properties of
these disturbed lands.
Sewage sludge can be used to return barren land to
productivity or to provide the vegetative cover necessary
for controlling soil erosion. A relatively large amount of
sewage sludge must be applied to a land area (7 to
450 t DW/ha) to provide sufficient organic matter and
nutrients capable of supporting vegetation until a self-
sustaining ecosystem can be established. Because of
these typically large, one-time applications of sewage
sludge at reclamation sites, the Part 503 rule allows
sewage sludge application at reclamation sites to ex-
ceed agronomic rates for N if approved by the permitting
authority, who may require surface water or ground-
water monitoring as a condition for sewage sludge ap-
plication, if deemed necessary.
Pilot and full-scale demonstration projects have been
undertaken in at least 20 states to study the application
of sewage sludge to reclaimed lands. The results sug-
gest that sewage sludge can be used effectively to
reclaim disturbed sites when the application of sewage
sludge is managed properly. The following factors must
be considered: the degree to which the sewage sludge
is stabilized, sewage sludge application rates, the de-
gree of land slope, and siting issues (e.g., quality of
aquifer, depth to ground water).
Because sewage sludge typically is applied only once
to land reclamation sites, an ongoing program of sew-
age sludge application to disturbed lands requires that
a planned sequence of additional sites be available for
the life of the program. This objective may be achieved
through arrangements with land owners and mining
firms active in the area or through planned sequential
rehabilitation of existing disturbed land areas. Once a
reclamation site is reclaimed, sewage sludge can be
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applied to the site in compliance with the requirements
for the type of site it may become (e.g., agricultural or
forest land, or a public contact site). For example, re-
claimed areas may be used for crop production using
agronomic rates of sewage sludge application.
2.4.2 Advantages of Land Application at
Reclamation Sites
Land application may be extremely attractive in areas
where disturbed and marginal lands exist because of the
benefit to the treatment works in using or disposing its
sewage sludge and to the environment through recla-
mation of unsightly, largely useless land areas.
Sewage sludge has several characteristics that makes
it suitable for reclaiming and improving disturbed lands
and marginal soils. One of the most important is the
sewage sludge organic matter which (1) improves soil
physical properties by improving granulation, reducing
plasticity and cohesion, and increasing water-holding
capacity; (2) increases the soil cation exchange capac-
ity; (3) supplies plant nutrients; (4) increases and buffers
soil pH; and (5) enhances the rejuvenation of microor-
ganism populations and activity.
The natural buffering capacity and pH of most sewage
sludge will improve the acidic or moderately alkaline
conditions found in many mine soils. Immobilization of
heavy metals is pH-dependent, so sewage sludge ap-
plication reduces the potential for acidic, metal-laden
runoff and leachates. Sewage sludge is also desirable
because the nutrients contained in it may substantially
reduce commercial fertilizer needs. Furthermore, sew-
age sludge helps to increase the number and activity of
soil microorganisms.
The amount of sewage sludge applied in a single appli-
cation can often be greater for land reclamation than for
agricultural land application, provided that the quantities
applied do not pose a serious risk of future plant phyto-
toxicity or unacceptable nitrate leaching into a potable
ground water aquifer, and if regulatory agency approval
is granted. In some cases, serious degradation of sur-
face water and ground water may already exist at the
proposed site, and a relatively heavy sewage sludge
addition with subsequent revegetation can be justified
as improving an already bad situation.
The treatment works may not have to purchase land for
reclamation projects. In addition, disturbed or marginal
lands are usually located in rural, relatively remote
areas.
2.4.3 Limitations of Land Application at
Reclamation Sites
Plant species for revegetation at reclamation sites
should be carefully selected for their suitability to local
soil and climate conditions. If crops intended for animal
feed or human consumption are planted, the require-
ments for agricultural land application of sewage sludge
have to be met.
Reclamation sites, especially old abandoned mining
sites, often have irregular, excessively eroded terrain.
Extensive grading and other site preparation steps may
be necessary to prepare the site for sewage sludge
application. Similarly, disturbed lands often have irregu-
lar patterns of soil characteristics. This may cause diffi-
culties in sewage sludge application, revegetation, and
future site monitoring.
2.5 Land Application at Public Contact
Sites, Lawns, and Home Gardens
2.5.1 Purpose and Definition
Approximately 9 percent of sewage sludge that is land
applied annually is used as a soil conditioner or fertilizer
on land having a high potential for public contact. These
public contact sites include public parks, ball fields,
cemeteries, plant nurseries, highway median strips, golf
courses, and airports, among others. Another 12 per-
cent of land applied sewage sludge is sold or given away
in a bag or other container, most likely for application to
public contact sites, lawns, and home gardens. Usually,
sewage sludge that is sold or given away in a bag or
other container is composted, or heat dried (and some-
times formed into pellets). Composted sewage sludge is
dry, practically odorless, and easy to distribute and han-
dle. Bagged or otherwise containerized sewage sludge
that is sold or given away often is used as a substitute
for topsoil and peat on lawns, golf courses, parks, and
in ornamental and vegetable gardens. Yield improve-
ments have been valued at $35 to $50 per dry ton over
other potting media (U.S. EPA, 1993).
There have been two basic approaches to sewage
sludge use in parks and recreational areas: (1) land
reclamation followed by park establishment, and (2) use
of sewage sludge as a substitute for conventional fertil-
izers in the maintenance of established parkland vege-
tation. Sewage sludge can supply a portion of the
nutrients required to maintain lawns, flower gardens,
shrubs and trees, golf courses, recreational areas, etc.
2.5.2 Advantages of Land Application at
Public Contact Sites, Lawns, and Home
Gardens
Programs designed to promote sewage sludge land
application to public contact sites, lawns, and home
gardens are particularly advantageous for treatment
works having limited opportunities for other types of land
application (e.g., at forest sites, agricultural land, and
reclamation sites).
-------
In some areas of the country, a high demand exists for
bagged sewage sludge applied to public contact sites,
lawns, and home gardens. This is, in part, due to the fact
that sewage sludge often is sold at lower cost than many
commercial fertilizers, or is given away free. In addition,
although the nutrient content of many sewage sludges
is lower than that of commercial fertilizers, sewage
sludge contains organic matter that can release nutri-
ents more slowly, minimizing potential "burning" of
plants (Lue-Hing et al., 1992).
2.5.3 Limitations of Land Application at
Public Contact Sites, Lawns, and Home
Gardens
Many of the strictest requirements of the Part 503 rule,
in particular the pollutant limits for metals and the patho-
gen requirements, must be met for sewage sludge ap-
plied to lawns, home gardens, and public contact sites.
This is because of the high potential for human contact
with the sewage sludge at these sites and because it is
not possible to impose site restrictions when sewage
sludge is sold or given away in a bag or other container
for application to the land. While meeting the pollutant
limits and pathogen requirements will not be difficult for
many sewage sludge preparers, some treatment works
have reported problems in meeting certain of these
requirements, and corrective measures would involve
increased operational costs.
In general, the costs of a program that markets sewage
sludge for use on lawns, home gardens, and public
contact sites may be greater than the costs of direct land
application. Major costs include those for sewage
sludge dewatering, processes to achieve adequate
pathogen and vector attraction reduction, market devel-
opment, and transportation.
2.6 References
Lue-Hing, C., D.R. Zenz, and R. Kuchenrither, eds. 1992. Municipal
sewage sludge management: Processing, utilization, and dis-
posal. In: Water quality management library, Vol. 4. Lancaster, PA:
Technomic Publishing Company, Inc.
Smith, W, and J. Evans. 1977. Special opportunities and problems
in using forest soils for organic waste application. In: Elliott, L.F.,
and J.F. Stevenson, eds. Soils for management of organic wastes
and wastewaters. Soil Science Society of America, Madison, Wl.
U.S. EPA. 1993. Standards for the use or disposal of sewage sludge.
Fed. Reg. 58(32):9259.
10
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Chapter 3
Overview of the Part 503 Regulatory Requirements for Land Application of
Sewage Sludge
3.1 General
The federal Part 503 rule (40 CFR Part 503) establishes
requirements for land applying sewage sludge (includ-
ing domestic septage) to ensure protection of public
health and the environment when sewage sludge is
used for its soil conditioning or fertilizing properties.
Promulgated in 1993, Part 503 covers sewage sludge
sold or given away in bulk, bags, or other containers for
application to agricultural land (e.g., cropland, pastures,
and rangelands), forests, reclamation sites (e.g., mine
spoils, construction sites, and gravel pits), public contact
sites (e.g., parks, plant nurseries), and lawns and home
gardens. The rule's land application requirements also
pertain to material derived from sewage sludge. Such
materials include sewage sludge that has undergone a
change in quality through treatment (e.g., composting,
drying) or mixing with other materials (e.g., wood chips)
after it leaves the treatment works where it was gener-
ated. Part 503 also covers surface disposal and incin-
eration of sewage sludge, which are beyond the scope
of this manual.
This chapter highlights key aspects of the Part 503 rule
as they pertain to land application of sewage sludge,
including general requirements, pollutant limits, man-
agement practices, pathogen and vector attraction re-
duction, frequency of monitoring, recordkeeping, and
reporting, as shown in Chapter 1, Figure 1-1. For a
discussion of Part 503 requirements for the land appli-
cation of domestic septage, see Chapter 11. More de-
tailed discussions of the rule can be found in other EPA
documents (U.S. EPA, 1992a; 1992b; 1994).
For most types of sewage sludge other than those spe-
cifically excluded (see Table 3-1), the requirements in 40
CFR Part 503 supersede those in 40 CFR Part 257—the
previous rule that governed the use or disposal of sew-
age sludge from 1979 to 1993. Part 503 establishes
minimum standards; when necessary to protect public
health and the environment, the permitting authority
may impose requirements that are more stringent than,
or in addition to, those stipulated in the Part 503 rule.
The rule leaves to the discretion of individual states
whether to administer a more restrictive sewage sludge
use or disposal program than is required by the federal
regulation. A state program may even define sewage
sludge differently than the federal regulation (see Table
3-2). Also, while state officials are encouraged to submit
their sewage sludge programs for review and approval
by EPA, they are not required to do so. A disadvantage
of an unapproved state program for the regulated com-
munity is the added complexity of complying with all
applicable federal and state requirements, including the
most restrictive requirements of both the state program
and the federal rule. Both state and federal operating
permits also might be required in a state with a sewage
sludge management program that has not been ap-
proved by EPA.
For the most part, the requirements of the Part 503 rule
are implemented through permits issued by EPA or by a
state that administers an EPA-approved sewage sludge
management program (see Table 3-3). But the Part 503
rule is "self-implementing," meaning that persons who
generate, prepare, or land apply sewage sludge must
comply with the rule even if they are not specifically
required to obtain a permit.
To ensure compliance with the rule, regulatory officials
have the authority to inspect operations, review records,
sample applied sewage sludge, and generally respond
to complaints concerning public health or public nui-
sances. EPA also is prepared to pursue enforcement
actions when necessary to address violations, whether
willful or the result of negligence. In the absence of a
government enforcement action, private citizens have
standing to pursue civil remedies against a violator un-
der the Clean Water Act.
3.2 Pollutant Limits
Subpart B of the Part 503 rule prohibits the land appli-
cation of sewage sludge that exceeds pollutant limits
termed ceiling concentrations in the rule for 10 metals,
and places restrictions on the land application of sew-
age sludge that exceeds additional pollutant limits speci-
fied in the rule (pollutant concentrations, cumulative
11
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Table 3-1. Types of Sludge, Septage, and Other Wastewater
Solids Excluded From Coverage Under Part 503
Table 3-2. Definitions of Terms Under the Part 503 Rule
Sludge Type
Applicable Federal
Requirements
Sewage sludge that is hazardous
in accordance with 40 CFR Part
261
Sewage sludge with a PCB
concentration equal to or greater
than 50 mg/kg total solids (dry
weight basis)
Grit (e.g., small pebbles and
sand) and screenings (e.g., large
materials such as rags) generated
during preliminary treatment of
sewage sludge
Commercial septage (e.g., grease
from a grease trap at a
restaurant) and industrial septage
(e.g., liquid or solid material
removed from a septic tank that
receives industrial wastewater)
and mixtures of domestic septage
and commerical or industrial
septage
Industrial sludge and sewage
sludge generated at an industrial
facility during the treatment of
industrial wastewater with or
without combined domestic
sewage
Incinerator ash generated during
the firing of sewage sludge in a
sewage sludge incinerator
Sewage sludge co-fired in an
incinerator with other wastes
(other than an auxiliary fuel)
Drinking water sludge generated
during the treatment of either
surface water or ground water
used for drinking water
Treatment of sewage sludge prior
to final use or disposal (e.g.,
processes such as thickening,
dewatering, storage, heat drying)
Storage of sewage sludge as
defined in Part 503
40 CFR Parts 261-268
40 CFR Part 761
40 CFR Part 257 (if
land applied)
40 CFR Part 258 (if
placed in a municipal
solid waste landfill)
40 CFR Part 257 (if
land applied)
40 CFR Part 258 (if
placed in a municipal
solid waste landfill)
40 CFR Part 257 (if
land applied)
40 CFR Part 258 (if
placed in a municipal
solid waste landfill)
40 CFR Part 257 (if
land applied)
40 CFR Part 258 (if
placed in a municipal
solid waste landfill) or
40 CFR Parts 261-268
(if hazardous)
40 CFR Parts 60, 61
40 CFR Part 257 (if
land applied)
40 CFR Part 258 (if
placed in a municipal
solid waste landfill)
None (except for
operational parameters
used to meet Part 503
pathogen and vector
attraction reduction
requirements)
None
Bulk Sewage Sludge
Domestic Septage
Domestic Sewage
Preparer
Scum, Grit, and
Screenings
Sewage Sludge
Treatment Works
Sewage sludge that is not sold or given
away in a bag or other container for
application to land.
A liquid or solid material removed from a
septic tank, cesspool, portable toilet, Type
III marine sanitation device, or similar
system that receives only domestic
sewage. Domestic septage does not
include grease-trap pumpings or
commercial/industrial wastes.
Waste and wastewater from humans or
household operations that is discharged
to or otherwise enters a treatment works.
The person who generates sewage
sludge during the treatment of domesitc
sewage in a treatment works, or the
person who derives a material from
sewage sludge.
Scum consists of floatable materials in
wastewater and is regulated by Part 503
if it is subject to one of the Part 503 use
or disposal practices because it is, by
definition, sewage sludge. Grit, which is
regulated under 40 CFR Part 257 when
applied to the land, consists of heavy,
coarse, inert solids (e.g., sand, silt,
gravel, ashes, corn grains, seed, coffee
ground, and bottle caps) associated with
raw wastewater. Screenings, which also
are regulated under Part 257 when
applied to the land, consist of such solids
as rags, sticks, and trash found in the
raw wastewater.
A solid, semi-solid, or liquid residue
generated during the treatment of
domestic sewage in a treatment
works. Sewage sludge includes scum
or solids removed in primary,
secondary, or advanced wastewater
treatment processes and any material
derived from sewage sludge (e.g., a
blended sewage sludge/fertilizer
product), but does not include grit and
screening or ash generated by the
firing of sludge in an incinerator. Part
503 considers domestic septage as
sewage sludge and sets separate
requirements for domestic septage
applied to agricultural land, forests, or
reclamation sites.
A federally, publicly, or privately owned
device or system used to treat (including
recycle and reclaim) either domestic
sewage or a combination of domestic
sewage and industrial waste of a liquid
nature.
pollutant loading rates [CPLRs], or annual pollutant
loading rates [APLRs]). For one of the regulated met-
als, molybdenum, only ceiling concentrations apply
while EPA reconsiders the CPLRS, pollutant concen-
tration limits, and APLRs established by the rule. The
different types of pollutant limits included in Part 503
are discussed below and are listed in Table 3-4.
3.2.1 Ceiling Concentration Limits
All sewage sludge applied to land must meet Part 503
ceiling concentration limits for the 10 regulated pollutants.
Ceiling concentration limits are the maximum allowable
concentration of a pollutant in sewage sludge to be land
applied. If the ceiling concentration limit for any one of the
regulated pollutants is exceeded, the sewage sludge can-
not be land applied. The ceiling concentration limits were
12
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Table 3-3. Who Must Apply for a Permit?
Treatment Works Treating Domestic Sewage (TWTDS)
Required to Apply for a Permit
• All generators of sewage sludge that is regulated by Part 503
(including all POTWs)
• Industrial facilities that separately treat domestic sewage and
generate sewage sludge that is regulated by Part 503
• All surface disposal site owner/operators
• All sewage sludge incinerator owner/operators
• Any other person designated by the permitting authority as a
TWTDS
TWTDS and Other Persons Not Automatically Required To
Apply for a Permit3
• Any person (e.g., individual, corporation, or government entity)
who changes the quality of sewage sludge regulated by Part 503
(e.g., sewage sludge blenders or processers)
• Sewage sludge land appliers, haulers, persons who store, or
transporters who do not generate or do not change the quality of
the sludge
• Land owners of property on which sewage sludge is applied
• Domestic septage pumpers/haulers/treaters/appliers
• Sewage sludge packagers/baggers (who do not change the
quality of the sewage sludge)
3 EPA may request permit applications from these persons when
necessary to protect public health and the environment from rea-
sonably anticipated effects of pollutants that may be present in
sewage sludge.
b If all the sewage sludge received by a sludge blender or composter
is exceptional quality (EQ) sludge, then no permit will be required
for the person who receives or processes the EQ sludge.
developed to prevent the land application of sewage
sludge containing high concentrations of pollutants.
3.2.2 Pollutant Concentration Limits
Pollutant concentration limits are the most stringent pol-
lutant limits included in Part 503 for land application.
These limits help ensure that the quality of land-applied
sewage sludge remains at least as high as the quality
of sewage sludge at the time the Part 503 rule was
developed. Sewage sludge meeting pollutant concen-
tration limits, as well as certain pathogen and vector
attraction reduction requirements (see Section 3.7.1),
generally is subject to fewer Part 503 requirements than
sewage sludge meeting cumulative pollutant loading
rates (CPLRs) (discussed below).
3.2.3 Cumulative Pollutant Loading Rates
(CPLRs)
A cumulative pollutant loading rate (CPLR) is the maxi-
mum amount of a pollutant that can be applied to a site
by all bulk sewage sludge applications made after July
20, 1993. CPLRs pertain only to land application of bulk
sewage sludge, as defined in Part 503. When the maxi-
mum CPLR is reached at the application site for any one
of the 10 metals regulated by the Part 503 rule, no
additional sewage sludge subject to the CPLRs can be
applied to the site. If a CPLR is reached at a site, only
sewage sludge that meets the pollutant concentration
limits could be applied to that site.
Table 3-4. Part 503 Land Application Pollutant Limits for Sewage Sludge
Pollutant
Ceiling Concentration
Limits (milligrams per
kilogram)a'b
Pollutant Concentration
Limits (milligrams per
kilogram)3'0
Cumulative Pollutant
Loading Rate Limits
(kilograms per hectare)
Annual Pollutant
Loading Rate Limits
(kilograms per hectare
per 365-day period)
Arsenic
Cadmium
Chromiumd
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
Applies to:
From Part 503
75
85
3,000
4,300
840
57
75
420
100
7,500
All sewage sludge that
is land applied
Table 1, Section 503.13
41
39
1,200
1,500
300
17
d
420
36d
2,800
Bulk sewage sludge and
bagged sewage sludge8
Table 3, Section 503.13
41
39
3,000
1,500
300
17
d
420
100
2,800
Bulk sewage sludge
Table 2, Section 503.13
2.0
1.9
150
75
15
0.85
d
21
5.0
140
Bagged sewage sludge8
Table 4, Section 503.13
Dry-weight basis.
b All sewage sludge samples must meet the ceiling concentrations, at a minimum, to be eligible for land application (instantaneous values).
c Monthly average.
d EPA is re-examining these limits.
8 Bagged sewage sludge is sold or given away in a bag or other container for application to the land.
13
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3.2.4 Annual Pollutant Loading Rates
(APLRs)
3.3 Management Practices
The annual pollutant loading rate (APLR) is the maxi-
mum amount of a pollutant that can be applied to a site
within a 12-month period from sewage sludge that is
sold or given away in a bag or other container for
application to land.1 To meet the APLRs, the pollutant
concentration in sewage sludge, multiplied by the "an-
nual whole sludge application rate," as determined in
Appendix A of the Part 503 rule, must not cause any of
the APLRs to be exceeded. APLRs rather then CPLRs
are used for sewage sludge sold or given away in a bag
or other container for application to land because con-
trolling cumulative applications of these types of sewage
sludge would not be feasible.
APLRs are based on a 20-year site life, which EPA
considers a conservative estimate because sewage
sludge sold or given away in small quantities will most
likely be applied to lawns, home gardens, or public
contact sites. Sewage sludge is not likely to be applied
to such types of land for longer than 20 years; indeed,
20 consecutive years of application is unlikely (U.S.
EPA, 1992a).
3.2.5 Why Organic Pollutants Were Not
Included in Part 503
The Part 503 regulation does not establish pollutant
limits for any organic pollutants because EPA deter-
mined that none of the organics considered for regu-
lation2 pose a public health or environmental risk
from land application of sewage sludge (U.S. EPA,
1992a). EPA used the following criteria to make this
determination:
• The pollutant is banned or restricted in the United
States or is no longer manufactured in the United
States; or
• The pollutant is not present in sewage sludge at sig-
nificant frequencies of detection, based on data gath-
ered from the 1990 NSSS; or
• The limit for a pollutant from EPAs exposure assess-
ment is not expected to be exceeded in sewage
sludge that is used or disposed, based on data from
the NSSS.
1 "Other containers" are defined in Part 503 as open or closed recep-
tacles, such as buckets, boxes, cartons, or vehicles, with a load
capacity of 1 metric ton or less.
2 Aldrin/dieldrin, benzene, benzo(a)pyrene, bis(2ethylhexyl)phthalate,
chlordane, DDT (and its derivatives ODD and DDE), dimethyl ni-
trosamine, heptachlor, hexachlorobenzene, hexachlorobutadiene,
lindane, PCBs, toxaphene, and trichloroethylene.
As described in Table 3-5, the Part 503 rule specifies
management practices that must be followed when sew-
age sludge is land applied. Management practices re-
quired for bulk sewage sludge meeting Part 503
pollutant concentration limits or cumulative pollutant
loading rates protect water quality and the survival of
threatened or endangered species. For example, bulk
sewage sludge that meets these pollutant limits cannot
be applied to sites that are flooded or frozen in such a
way that the sewage sludge might enter surface waters
or wetlands. Also, any direct or indirect action that
diminishes the likelihood of a threatened or endan-
gered species' survival by modifying its critical habi-
tat is prohibited. Other Part 503 management practices
are listed in Table 3-5.
Table 3-5. Part 503 Land Application Management Practices
For Bulk Sewage Sludge3
Bulk sewage sludge cannot be applied to flooded, frozen, or
snow-covered agricultural land, forests, public contact sites, or
reclamation sites in such a way that the sewage sludge enters a
wetland or other waters of the United States (as defined in 40
CFR Part 122.2), except as provided in a permit issued pursuant
to Section 402 (NPDES permit) or Section 404 (Dredge and Fill
Permit) of the Clean Water Act, as amended.
Bulk sewage sludge cannot be applied to agricultural land, forests,
or reclamation sites that are 10 meters or less from U.S. waters,
unless otherwise specified by the permitting authority.
If applied to agricultural lands, forests, or public contact sites, bulk
sewage sludge must be applied at a rate that is equal to or less
than the agronomic rate for the site. Sewage sludge applied to
reclamation sites may exceed the agronomic rate if allowed by the
permitting authority.
Bulk sewage sludge must not harm or contribute to the harm of a
threatened or endangered species or result in the destruction or
adverse modification of the species' critical habitat when applied to
the land. Threatened or endangered species and their critical
habitats are listed in Section 4 of the Endangered Species Act.
Critical habitat is defined as any place where a threatened or
endangered species lives and grows during any stage of its life
cycle. Any direct or indirect action (or the result of any direct or
indirect action) in a critical habitat that diminishes the likelihood of
survival and recovery of a listed species is considered destruction
or adverse modification of a critical habitat.
For Sewage Sludge Sold or Given Away in a Bag or Other
Container for Application to the Land3
A label must be affixed to the bag or other container, or an
information sheet must be provided to the person who receives
this type of sewage sludge in another container. At a minimum, the
label or information sheet must contain the following information:
• the name and address of the person who prepared the sewage
sludge for sale or give-away in a bag or other container;
• a statement that prohibits application of the sewage sludge to the
land except in accordance with the instructions on the label or
information sheet;
• an AWSAR (see Table 3-18) for the sewage sludge that does not
cause the APLR pollutant limits to be exceeded.
3 These management practices do not apply if the sewage sludge is
of "exceptional quality," as defined in section 3.7.
14
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The preparer of sewage sludge that is sold or given
away in a bag or other container for application to land
must comply with the Part 503 management practice
that requires the preparer to provide application rate
information, as well as other pertinent data, to the land
applier of sewage sludge meeting annual pollutant load-
ing rates (as discussed in Table 3-5 and Section 3.7.4).
3.4 Operational Standards for
Pathogens and Vector Attraction
Reduction
Subpart D of the Part 503 rule describes requirements
for land application of sewage sludge (and domestic
septage, as discussed in Chapter 11) that reduce the
potential forthe spread of disease, thus protecting public
health and the environment. The Part 503 Subpart D
requirements cover two characteristics of sewage sludge:
• Pathogens. Part 503 requires the reduction of poten-
tial disease-bearing microorganisms called patho-
gens (such as bacteria and viruses) in sewage sludge.
• Vector Attraction. Part 503 also requires that the po-
tential for sewage sludge to attract vectors (e.g., ro-
dents, birds, insects) that can transport pathogens
away from the land application site be reduced.
Compliance with the Part 503 pathogen and vector at-
traction reduction requirements, summarized below,
must be demonstrated separately.
3.4.1 Pathogen Reduction Requirements
The Part 503 pathogen reduction requirements for sew-
age sludge are divided into two categories: Class A and
Class B, as shown in Table 3-6. The implicit goal of the
Class A requirements is to reduce the pathogens in
sewage sludge (including Salmonella sp. bacteria, en-
teric viruses, and viable helminth ova) to below detect-
able levels. When this goal is achieved, Class A sewage
sludge can be land applied without any pathogen-re-
lated restrictions on the site (see Section 3.7).
The implicit goal of the Class B requirements is to
ensure that pathogens have been reduced to levels that
are unlikely to pose a threat to public health and the
environment under specific use conditions. Site restric-
tions on the land application of Class B sewage sludge
minimize the potential for human and animal contact
with the sewage sludge until environmental factors have
reduced pathogens to below detectable levels. In addi-
tion, to further reduce the likelihood of human contact
with pathogens, Class B sewage sludge cannot be sold
or given away in a bag or other container for land
application. Part 503 Class A and B pathogen reduction
requirements are summarized below; another EPA
document (U.S. EPA, 1992b) provides a detailed discus-
sion of pathogen reduction requirements under Part 503.
Table 3-6. Summary of Class A and Class B Pathogen
Alternatives
CLASS A
In addition to meeting the
requirements in one of the six
alternatives listed below, fecal
coliform or Salmonella sp.
bacterial levels must meet
specific densities at the time
of sewage sludge use or
disposal, when prepared for
sale or give-away in a bag or
other container for application
to the land, or when prepared
to meet the requirements in
503.10(b), (c), (e), or (f)
Alternative 1: Thermally
Treated Sewage Sludge
Use one of four
time-temperature regimes
Alternative 2: Sewage Sludge
Treated in a High pH-High
Temperature Process
Specifies pH, temperature,
and air-drying requirements
Alternative 3: For Sewage
Sludge Treated in Other
Processes
Demonstrate that the process
can reduce enteric viruses
and viable helminth ova.
Maintain operating conditions
used in the demonstration
Alternative 4: Sewage
Sludge Treated in Unknown
Processes
Demonstration of the process
is unnecessary. Instead, test
for pathogens—Salmonella
sp. bacteria, enteric viruses,
and viable helminth ova—at
the time the sewage sludge is
used or disposed, or is
prepared for sale or
give-away in a bag or other
container for application to
the land, or when prepared to
meet the requirements in
503.10(b), (c), (e), or (f)
Alternative 5: Use of PFRP
Sewage sludge is treated in
one of the processes to further
reduce pathogens (PFRP)
Alternative 6: Use of a
Process Equivalent to PFRP
Sewage sludge is treated in a
process equivalent to one of
the PFRPs, as determined by
the permitting authority
CLASS B
The requirements in one of
the three alternatives below
must be met in addition to
Class B site restrictions
Alternative 1: Monitoring of
Indicator Organisms
Test for fecal coliform density
as an indicator for all
pathogens at the time of
sewage sludge use or disposal
Alternative 2: Use of PSRP
Sewage sludge is treated in one
of the processes to significantly
reduce pathogens (PSRP)
Alternative 3: Use of
Processes Equivalent to
PSRP
Sewage sludge is treated in a
process equivalent to one of
the PSRPs, as determined by
the permitting authority
Note: Details of each
alternative for meeting the
requirements for Class A and
Class B designations are
provided in Section 3.4.
3.4.1.1 Class A Pathogen Requirements
Sewage sludge that must meet the Class A pathogen
requirements includes sewage sludge that is sold or
given away in a bag or other container for application to
land and bulk sewage sludge that is applied to a lawn
or home garden. Part 503 Subpart D establishes six
alternatives for demonstrating that sewage sludge
meets Class A pathogen reduction requirements (Table
3-6). The rule requires that the density of fecal conforms
be less than 1,000 Most Probable Number (MPN) per
gram total solids (dry weight) or that Salmonella sp.
bacteria be less than 3 per 4 grams total solids, as
discussed in Table 3-7.
15
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Table 3-7. Pathogen Requirements for All Class A Alternatives Table 3-8.
The following requirements must be met for all six Class A
pathogen alternatives. Either:
• the density of fecal coliform in the sewage sludge must be less
than 1,000 most probable number (MPN) per gram total solids
(dry-weight basis),
or
• the density of Salmonella sp. bacteria in the sewage sludge must
be less than 3 MPN per 4 grams of total solids (dry-weight basis).
This requirement must be met at one of the following times:
• when the sewage sludge is used or disposed;
• when the sewage sludge is prepared for sale or give-away in a
bag or other container for land application; or
• when the sewage sludge or derived material is prepared to meet
the Part 503 requirements in 503.10(b), (c), (e), or (f)
Pathogen reduction must take place before or at the same time as
vector attraction reduction, except when the pH adjustment or
percent solids vector attraction reduction options are met, or if
vector attraction reduction is accomplished through injection or
incorporation.
Each of the six alternatives for meeting Class A patho-
gen reduction requirements includes monitoring require-
ments to ensure that substantial regrowth of pathogenic
bacteria does not occur afterthe sewage sludge meets the
pathogen reduction requirements prior to use or disposal.
The timing of Class A pathogen reduction in relation to
vector attraction reduction requirements (see Section
3.4.2) is important when certain vector attraction reduc-
tion options are used. Part 503 requires that Class A
pathogen reduction be accomplished before or at the same
time as vector attraction reduction, except when vector
attraction reduction is achieved by alkali addition or drying.
The following discussion summarizes the Part 503 Class
A pathogen reduction alternatives. For a more complete
discussion of these alternatives, see Environmental Regu-
lations and Technology: Control of Pathogens and Vector
Attraction in Sewage Sludge (U.S. EPA, 1992b).
Alternative 1: Thermally Treated Sewage Sludge
This alternative may be used when the pathogen reduc-
tion process relies on specific time-temperature regimes
to reduce pathogens (Table 3-8). The approach involves
calculating the heating time necessary at a particular
temperature to reduce a sewage sludge's pathogen con-
tent to below detectable levels. The need to conduct
time-consuming and expensive tests for the presence of
specific pathogens can be avoided with this approach.
The microbiological density portion of the requirement
(i.e., the regrowth requirement) is designed to ensure
that the microbiological reductions expected as a result
of the time-temperature regimes have actually been
attained and that regrowth has not occurred. Equations
for each of the four time-temperature regimes takes into
The Four Time-Temperature Regimes for Pathogen
Reduction Under Class A, Alternative 1
Regime
A
B
C
D
Applies to:
Sewage sludge
with 7% solids or
higher (except
those covered by
Regime B)
Sewage sludge
with 7% solids or
higher in the
form of small
particles heated
by contact with
either warmed
gases or an
immiscible liquid
Sewage sludge
with less than
7% solids
Sewage sludge
with less than
7% solids
Requirement
Temperature of
sewage sludge
must be 50°C
or higher for
not less than
20 minutes
Temperature of
sewage sludge
must be 50°C
or higher for
not less than
1 5 seconds
Heated for
more than 15
seconds but
less than 30
minutes
Temperature of
sludge is 50°C
or higher with
at least 30
minutes contact
time
Time-Temperature
Relationship3
131,700,000
-| QO. 14007
(Equation 3 of
Section 503.32)
131,700,000
10o.i40or
131,700,000
-| QO. 14007
50,070,000
U 10 0.14007
(Equation 4 of
Section 503.32)
' D = time in days; T = temperature in degrees Celsius.
account the percent of solids in the sewage sludge and
the operating parameters of the treatment process.
Alternative 2: Sewage Sludge Treated in a High
pH-High Temperature Process
This alternative may be used when the pathogen reduc-
tion process relies on a particular high temperature-high
pH process that has been demonstrated to be effective
in reducing pathogens to below detectable levels. The
high pH (>12 for more than 72 hours) and high tempera-
ture (above 52°C [126°F] for at least 12 hours while pH
is >12) for prolonged periods allow a less stringent time-
temperature regime than the requirements under Alter-
native 1. After the 72-hour period during which the pH
of the sewage sludge is above 12, the sewage sludge
must be air dried to achieve a percent solids content of
greater than 50 percent. As when thermal processing is
used, monitoring for regrowth of pathogenic bacteria (fecal
coliforms orsalmonellae) must be conducted (Table 3-7).
Alternative 3: Sewage Sludge Treated in Other
Processes
This alternative applies to sewage sludge treated by
processes that do not meet the process conditions re-
quired by Alternatives 1 and 2. Alternative 3 relies on
comprehensive monitoring of fecal coliform or Salmo-
nella sp. bacteria; enteric viruses; and viable helminth
16
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ova to demonstrate adequate reduction of pathogens,
as specified in the Part 503 rule.
If no enteric viruses or viable helminth ova are present
before treatment (i.e., in the feed sewage sludge), the
sewage sludge is Class A with respect to pathogens until
the next monitoring episode. Monitoring is continued
until enteric viruses or viable helminth ova are detected
in the feed sewage sludge, at which point the treated
sewage sludge is analyzed to see if these organisms
survived treatment. If enteric virus and viable helminth
ova densities are below detection limits, the sewage
sludge meets Class A requirements and will continue to
do so as long as the treatment process is operated
underthe same conditions that successfully reduced the
enteric virus and viable helminth ova densities. Monitoring
for fecal coliform and Salmonella sp. bacteria, however,
must continue to be performed as indicated in Table 3-7.
Alternative 4: Sewage Sludge Treated in Unknown
Processes
This alternative is used primarily for stored sewage
sludge for which the history is unknown. It also can be
used when the process in which sewage sludge is
treated does not meet any of the descriptions of a
Process to Further Reduce Pathogens (PFRP). In this
alternative, a representative sample of the sewage
sludge must meet the Part 503 requirements for Salmo-
nella sp. or fecal coliform bacteria (as described in Table
3-7); enteric viruses; and viable helminth ova at the time
the sewage sludge is used or disposed, prepared for
sale or give-away in a bag or other container for appli-
cation to land, or prepared to meet "exceptional quality"
(EQ) land application requirements (as discussed later
in this chapter). The number of samples that have to be
collected and analyzed for pathogen densities is based
on the amount of sewage sludge that is land applied
annually (see the requirements for frequency of moni-
toring in the land application subpart of Part 503).
Alternative 5: Use of a PFRP
This alternative provides continuity with the 40 CFR Part
257 regulation (the predecessor to Part 503). For Alter-
native 5, sewage sludge qualifies as Class A if it has
been treated in one of the processes to further reduce
pathogens (PFRPs) (Table 3-9) and meets the regrowth
requirement in Table 3-7. The treatment processes must
be operated according to the PFRP process descrip-
tions summarized in Table 3-9 at all times. The list of
processes in Table 3-9 (which appears as Appendix B in
the Part 503 regulation) is similar to the PFRP ap-
proaches listed in Part 257, with two major differences:
• All requirements concerning vector attraction have
been removed.
Table 3-9. Processes To Further Reduce Pathogens (PFRPs)
Listed in the Part 503 Rule
1. Composting
Using either the within-vessel composting method or the static
aerated pile composting method, the temperature of the sewage
sludge is maintained at 55°C (131°F) or higher for 3 days.
Using the windrow composting method, the temperature of the
sewage sludge is maintained at 55°C (131°F) or higher for 15
days or longer. During the period when the compost is maintained
at 55°C (131°F) or higher, there shall be a minimum of five
turnings of the windrow.
2. Heat Drying
Sewage sludge is dried by direct or indirect contact with hot gases
to reduce the moisture content of the sewage sludge to 10% or
lower. Either the temperature of the sewage sludge particles
exceeds 80°C (176°F) or the wet bulk temperature of the gas in
contact with the sewage sludge as the sewage sludge leaves the
dryer exceeds 80°C (176°F).
3. Heat Treatment
Liquid sewage sludge is heated to a temperature of 180°C (356°F)
or higher for 30 minutes.
4. Thermophilic Aerobic Digestion
Liquid sewage sludge is agitated with air or oxygen to maintain
aerobic conditions and the mean cell residence time (i.e., the
solids retention time) of the sewage sludge is 10 days at 55°C
(131°F)to60°C (140°F).
5. Beta Ray Irradiation
Sewage sludge is irradiated with beta rays from an electron
accelerator at dosages of at least 1.0 megarad at room
temperature (ca. 20°C [68°F]).
6. Gamma Ray Irradiation
Sewage sludge is irradiated with gamma rays from certain
isotopes, such as Cobalt 60 and Cesium 137, at dosages of at
least 1.0 megarad at room temperature (ca. 20°C [68°F]).
7. Pasteurization
The temperature of the sewage sludge is maintained at 70°C
(158°F) or higher for 30 minutes or longer.
• All "add-on" processes listed in Part 257 are now
PFRPs because Part 503 contains separate require-
ments for vector attraction reduction.
Under this alternative, treatment processes classified as
PFRPs under Part 257 can continue to be operated;
however, microbiological monitoring (i.e., for fecal coli-
form or Salmonella sp. bacteria) must now be performed
to ensure that pathogen density levels are below detec-
tion limits and that regrowth of Salmonella sp. bacteria
does not occur between treatment and use or disposal
of the sewage sludge.
Alternative 6: Use of a Process Equivalent to a
PFRP
Under this alternative, sewage sludge is considered to
be Class A sewage sludge if it is treated by any process
equivalent to a PFRP and meets the regrowth require-
ment in Table 3-7. To be equivalent, a treatment process
17
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must be able to consistently reduce pathogens to levels
comparable to the reduction achieved by a listed PFRP.
Processes must be operated at all times at the parame-
ters described in the process description. The Part 503
rule gives the permitting authority responsibility for de-
termining equivalency. To assist in making such deter-
minations, the EPA's Pathogen Equivalency Committee
(PEC) serves as a resource, providing recommenda-
tions on the equivalency of processes; the PEC also
provides guidance to the regulated community. Equiva-
lency determinations can be made on a site-specific or
national basis. Processes recommended in Part 257 as
equivalent (Table 3-10) should yield sewage sludge that
meets Class A pathogen reduction requirements, as
long as microbiological requirements are also met.
Table 3-10. A Partial List of Processes Recommended as
Equivalent to PFRP Under Part 2571
Operator
Process Description
Scarborough Static pile aerated "composting" operation that
Sanitary uses fly ash from a paper company as a
District bulking agent. The process creates pile
Scarborough temperatures of 60°C to 70°C (140°F to
Mgjne 158°F) within 24 hours and maintains these
temperatures for up to 14 days. The material
is stockpiled after 7 to 14 days of "composting"
and then marketed.
Mount Holly Zimpro 50-gpm low-pressure wet air oxidation
Sewage process. The process involves heating raw
Authority primary sewage sludge to 177°C to 204°C
Mount Holly (350°F to 400°F) in a reaction vessel under
New Jersey
pressures of 250 to 400 psig for 15 to 30
minutes. Small volumes of air are introduced
into the process to oxidize the organic solids.
Miami-Dade Anaerobic digestion followed by solar drying.
Water and Sewage sludge is processed by anaerobic
Sewer digestion in two well-mixed digesters operating
Authority 'n ser'es 'n a temperature range of 35°C to
Miami, Florida f°C , Total residence time is 30
days. The sewage sludge is then centrifuged
to produce a cake of between 15% to 25%
solids. The sewage sludge cake is dried for 30
days on a paved bed at a depth of no more
than 46 cm (18 inches). Within 8 days of the
start of drying, the sewage sludge is turned
over at least once every other day until the
sewage sludge reaches a solids content of
greater than 70%.
1These processes were all recommended for site-specific equivalency.
3.4.1.2 Class B Pathogen Requirements
Bulk sewage sludge that is applied to agricultural land,
forests, public contact sites, or reclamation sites must
meet the Class B pathogen requirements if it does not
meet Class A pathogen requirements. Part 503 Subpart
D establishes three alternatives for demonstrating that
sewage sludge meets Class B pathogen requirements
(Table 3-6). The rule's implicit objective for all three
approaches is to ensure that pathogenic bacteria and
enteric viruses are reduced in density, as demonstrated
by a fecal coliform density in the treated sewage sludge
Table 3-11. Restrictions for the Harvesting of Crops and Turf,
Grazing of Animals, and Public Access on Sites
Where Class B Sewage Sludge is Land Applied
Restrictions for the harvesting of crops and turf:
1. Food crops with harvested parts that touch the sewage
sludge/soil mixture and are totally above ground shall not be
harvested for 14 months after application of sewage sludge.
2. Food crops with harvested parts below the land surface
where sewage sludge remains on the land surface for 4
months or longer prior to incorporation into the soil shall not
be harvested for 20 months after sewage sludge application.
3. Food crops with harvested parts below the land surface
where sewage sludge remains on the land surface for less
than 4 months prior to incorporation shall not be harvested for
38 months after sewage sludge application.
4. Food crops, feed crops, and fiber crops, whose edible parts
do not touch the surface of the soil, shall not be harvested for
30 days after sewage sludge application.
5. Turf grown on land where sewage sludge is applied shall
not be harvested for 1 year after application of the sewage
sludge when the harvested turf is placed on either land with a
high potential for public exposure or a lawn, unless otherwise
specified by the permitting authority.
Restriction for the grazing of animals:
1. Animals shall not be grazed on land for 30 days after
application of sewage sludge to the land.
Restrictions for public contact:
1. Access to land with a high potential for public exposure,
such as a park or ballfield, is restricted for 1 year after
sewage sludge application. Examples of restricted access
include posting with no trespassing signs, or fencing.
2. Access to land with a low potential for public exposure
(e.g., private farmland) is restricted for 30 days after sewage
sludge application. An example of restricted access is
remoteness.
of 2 million Most Probable Number (MPN) or colony-
forming units (CPU) per gram total solids sewage sludge
(dry-weight basis). Viable helminth ova are not neces-
sarily reduced in Class B sewage sludge.
Unlike Class A sewage sludge, which is essentially
pathogen-free, Class B sewage sludge contains some
pathogens. Therefore, site restrictions (Table 3-11) ap-
ply for a certain period when Class B sewage sludge is
land applied to allow environmental factors to further
reduce pathogens to below detectable levels. Addition-
ally, Class B sewage sludge must meet a vector attrac-
tion requirement (see Section 3.4.2). The three
alternatives for meeting Part 503 Class B pathogen
reduction requirements are summarized below; more
detailed information on Class B pathogen requirements
can be found in another EPAdocument (U.S. EPA, 1992b).
Alternative 1: Monitoring of Fecal Coliform
This alternative requires that seven samples of treated
sewage sludge be collected at the time of use or dis-
posal, and that the geometric mean fecal coliform den-
sity of these sample be less that 2 million CPU or MPN
per gram of sewage sludge solids (dry-weight basis).
Analysis of multiple samples is required during each
18
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monitoring period because the methods used to deter-
mine fecal coliform density (i.e., membrane filter meth-
ods and the MPN dilution method) have poor precision
and because sewage sludge quality tends to vary. Use
of at least seven samples is expected to reduce the
standard error to a reasonable value.
Alternative 2: Use of a PSRP
Under this alternative, which provides continuity with
Part 257, sewage sludge is considered to be Class B if
it is treated in one of the processes to significantly
reduce pathogens (PSRPs) (Table 3-12). The list of
processes (which appears as Appendix B in the Part 503
regulation) is similar to the PSRP approaches listed in Part
257, except that all conditions related to reduction of vector
attraction have been removed. Unlike the comparable
Class A requirement, this alternative does not require mi-
crobiological monitoring because public access to the site
is restricted, allowing time for environmental conditions to
reduce pathogens to below detectable levels.
Table 3-12. Processes to Significantly Reduce Pathogens
(PSRPs) Listed in Part 503
1. Aerobic Digestion
Sewage sludge is agitated with air or oxygen to maintain aerobic
conditions for a specific mean cell residence time (i.e., solids
retention time) at a specific temperature. Values for the mean cell
residence time and temperature shall be between 40 days at 20°C
(68°F) and 60 days at 15°C (59°F).
2. Air Drying
Sewage sludge is dried on sand beds or on paved or unpaved
basins. The sewage sludge dries for a minimum of 3 months.
During 2 of the 3 months, the ambient average daily temperature
is above 0°C (32°F).
3. Anaerobic Digestion
Sewage sludge is treated in the absence of air for a specific
mean cell residence time (i.e., solids retention time) at a specific
temperature. Values for the mean cell residence time and
temperature shall be between 15 days at 35°C to 55°C (131°F)
and 60 days at 20°C (68°F).
4. Composting
Using either the within-vessel, static aerated pile, or windrow
composting methods, the temperature of the sewage sludge is
raised to 40°C (104°F) or higher and remains at 40°C (104°F) or
higher for 5 days. For 4 hours during the 5-day period, the
temperature in the compost pile exceeds 55°C (131°F).
5. Lime Stabilization
Sufficient lime is added to the sewage sludge to raise the pH of
the sewage sludge to 12 after 2 hours of contact.
Alternative 3: Use of a Process Equivalent to a PSRP
Alternative 3 states that sewage sludge treated by any
process determined to be equivalent to a PSRP by the
permitting authority is considered to be a Class B sew-
age sludge. To assist the permitting authority in making
determinations, the EPA's Pathogen Equivalency Com-
mittee (PEC) serves as a resource, providing recom-
mendations on the equivalency of processes; the PEC
also provides guidance to the regulated community.
Equivalency determinations can be made on a site-spe-
cific or national basis. Processes recommended in Part
257 as equivalent (a partial list is provided in Table 3-13)
should yield sewage sludge that meets Class B patho-
gen requirements.
Table 3-13. Selected Processes Recommended as Equivalent
to PSRP Under Part 2571
Operator
Process Description
Town of Telluride, Combination oxidation ditch, aerated storage,
Colorado and drying process. Sewage sludge is treated
in an oxidation ditch for at least 26 days and
then stored in an aerated holding tank for up
to a week. Following dewatering to 18%
solids, the sewage sludge is dried on a paved
surface to a depth of 2 feet (0.6 m). The
sewage sludge is turned over during drying.
After drying to 30% solids, the sludge is
stockpiled prior to land application. Together,
the drying and stockpiling steps take
approximately 1 year. To ensure that PSRP
requirements are met, the stockpiling period
must include one full summer season.
Comprehensive Use of cement kiln dust (instead of lime) to
Materials treat sewage sludge by raising sewage sludge
Management, Inc. pH to at least 12 after 2 hours of contact.
Houston, Texas Dewatered sewage sludge is mixed with
cement kiln dust in an enclosed system.
N-Viro Energy Use of cement kiln dust and lime kiln dust
Systems, Ltd. (instead of lime) to treat sewage sludge by
Toledo, Ohio raising the pH. Sufficient lime or kiln dust is
added to sewage sludge to produce a pH of
12 for at least 12 hours of contact.
Public Works Anaerobic digestion of lagooned sewage
Department sludge. Suspended solids had accumulated in
Everett, a 30-acre (12-hectare) aerated lagoon that
Washington had been used to aerate wastewater. The
lengthy detention time in the lagoon (up to 15
years) resulted in a level of treatment
exceeding that provided by conventional
anaerobic digestion. The percentage of fresh
or relatively unstabilized sewage sludge was
very small compared to the rest of the
accumulation (probably much less than 1% of
the whole).
Haikey Creek Oxidation ditch treatment plus storage.
Wastewater Sewage sludge is processed in aeration
Treatment Plant basins followed by storage in aerated sludge
Tulsa, Oklahoma holding tanks. The total sewage sludge
aeration time is greater than the aerobic
digestion operating conditions specified in the
Part 503 regulation of 40 days at 20°C (68°F)
to 60 days at 15°C (59°F). The oxidation ditch
sludge is then stored in batches for at least
45 days in an unaerated condition or 30 days
under aerated conditions.
Ned K. Burleson & Aerobic digestion for 20 days at 30°C (86°F)
Associates, Inc. or 15 days at 35°C (95°F).
Fort Worth, Texas
1 All processes were recommended for site-specific equivalency, ex-
cept the N-Viro System, which was recommended for national
equivalency.
19
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3.4.2 Vector Attraction Reduction
Requirements
Subpart D in Part 503 establishes 10 options for dem-
onstrating that sewage sludge that is land applied meets
requirements for vector attraction reduction (Table 3-14).
The options can be divided into two general approaches
for controlling the spread of disease via vectors (such
as insects, rodents, and birds):
• Reducing the attractiveness of the sewage sludge to
vectors (Options 1 to 8).
• Preventing vectors from coming into contact with the
sewage sludge (Options 9 and 10).
Compliance with the vector attraction reduction require-
ments using one of the options described below must be
demonstrated separately from compliance with require-
ments for reducing pathogens in sewage sludge. Thus,
demonstration of adequate vector attraction reduction does
not demonstrate achievement of adequate pathogen
reduction. Part 503 vector attraction reduction require-
ments are summarized below; for a detailed discussion
of vector attraction requirements, see U.S. EPA(1992b).
3.4.2.1 Option 1: Reduction in Volatile Solids
Content
Under this option, vector attraction is reduced if the
mass of volatile solids in the sewage sludge is reduced
by at least 38 percent during the treatment of the sew-
age sludge. This percentage is the amount of volatile
solids reduction that can be attained by anaerobic or
aerobic digestion plus any additional volatile solids re-
duction that occurs before the sewage sludge leaves the
treatment works, such as through processing in drying
beds or lagoons, or when sewage sludge is composted.
Table 3-14. Summary of Vector Attraction Reduction Requirements for Land Application of Sewage Sludge Under Part 503
(U.S. EPA 1992b)
Requirement What Is Required?
Most Appropriate For:
Option 1 At least 38% reduction in volatile solids during sewage
503.33(b)(1) sludge treatment
Option 2 Less than 17% additional volatile solids loss during
503.33(b)(2) bench-scale anaerobic batch digestion of the sewage
sludge for 40 additional days at 30°C to 37°C (86°F to
99°F)
Option 3 Less than 15% additional volatile solids reduction during
503.33(b)(3) bench-scale aerobic batch digestion for 30 additional days
at 20°C (68°F)
Option 4 SOUR at 20°C (68°F) is <1.5 mg oxygen/hr/g total
503.33(b)(4) sewage sludge solids
Option 5 Aerobic treatment of the sewage sludge for at least 14
503.33(b)(5) days at over 40°C (104°F) with an average temperature
of over 45°C (113°F)
Option 6 Addition of sufficient alkali to raise the pH to at least 12 at
503.33(b)(6) 25°C (77°F) and maintain a pH >12 for 2 hours and a pH
>11.5 for 22 more hours
Option 7 Percent solids >75% prior to mixing with other materials
503.33(b)(7)
Option 8 Percent solids >90% prior to mixing with other materials
503.33(b)(8)
Option 9 Sewage sludge is injected into soil so that no significant
503.33(b)(9) amount of sewage sludge is present on the land surface
1 hour after injection, except Class A sewage sludge
which must be injected within 8 hours after the pathogen
reduction process.
Option 10 Sewage sludge is incorporated into the soil within 6 hours
503.33(b)(10) after application to land. Class A sewage sludge must be
applied to the land surface within 8 hours after the
pathogen reduction process, and must be incorporated
within 6 hours after application.
Sewage sludge processed by:
• Anaerobic biological treatment
• Aerobic biological treatment
• Chemical oxidation
Only for anaerobically digested sewage sludge
Only for aerobically digested sewage sludge with 2% or less
solids—e.g., sewage sludge treated in extended aeration
plants
Sewage sludge from aerobic processes (should not be used
for composted sludges). Also for sewage sludge that has
been deprived of oxygen for longer than 1-2 hours.
Composted sewage sludge (Options 3 and 4 are likely to be
easier to meet for sewage sludge from other aerobic
processes)
Alkali-treated sewage sludge (alkalies include lime, fly ash,
kiln dust, and wood ash)
Sewage sludges treated by an aerobic or anaerobic process
(i.e., sewage sludges that do not contain unstabilized solids
generated in primary wastewater treatment)
Sewage sludges that contain unstabilized solids generated
in primary wastewater treatment (e.g., any heat-dried
sewage sludges)
Liquid sewage sludge applied to the land. Domestic septage
applied to agricultural land, a forest, or a reclamation site
Sewage sludge applied to the land. Domestic septage
applied to agricultural land, forest, or a reclamation site.
20
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3.4.2.2 Option 2: Additional Digestion of
Anaerobically Digested Sewage Sludge
Under this option, an anaerobically digested sewage
sludge is considered to have achieved satisfactory vec-
tor attraction reduction if it loses less than 17 percent
additional volatile solids when it is anaerobically batch-
digested in the laboratory in a bench-scale unit at 30° to
37°C (86° to 99°F) for an additional 40 days.
Frequently, sewage sludge is recycled through the bio-
logical wastewater treatment section of a treatment
works or resides for long periods of time in the waste-
water collection system. During this time it undergoes
substantial biological degradation. If it is subsequently
treated by anaerobic digestion for a period of time, it is
adequately reduced in vector attraction; however, be-
cause sewage sludge enters the digester already par-
tially stabilized, the volatile solids reduction after
treatment is frequently less than 38%. The additional
digestion test is used to demonstrate that the sewage
sludge is indeed satisfactorily reduced in vector attraction.
3.4.2.3 Option 3: Additional Digestion of
Aerobically Digested Sewage Sludge
Under this option, an aerobically digested sewage
sludge with 2 percent or less solids is considered to
have achieved satisfactory vector attraction reduction if
it loses less than 15 percent additional volatile solids
when it is aerobically batch-digested in the laboratory in
a bench-scale unit at 20°C (68°F) or higher for an addi-
tional 30 days. This test can be run on sewage sludge
with up to 2 percent solids and does not require a
temperature correction for sewage sludge not initially
digested at 20°C. Sewage sludge with greater than 2
percent solids can be diluted to 2 percent solids with
effluent, and the test can then be run on the diluted
sludge.
This option is appropriate for aerobically digested sew-
age sludge, including sewage sludge from extended
aeration and oxidation ditch plants where the nominal
residence time of sewage sludge leaving the wastewa-
ter treatment processes generally exceeds 20 days. In
these cases, the sewage sludge may already have been
substantially reduced in biological degradability prior to
aerobic digestion.
3.4.2.4 Option 4: Specific Oxygen Uptake Rate
(SOUR) for Aerobically Digested Sewage
Sludge Treated in an Aerobic Process
For sewage sludge treated in an aerobic process (usu-
ally aerobic digestion), reduction in vector attraction can
also be demonstrated if the SOUR of the sewage sludge
to be land applied is equal to or less than 1.5 mg of
oxygen per hour per gram of total sewage sludge solids
(dry-weight basis) at 20°C (68°F). The basis of this test
is that if the sewage sludge consumes very little oxygen,
its value as a food source for vectors is very low and
thus vectors are unlikely to be attracted to the sewage
sludge.
Frequently, aerobically digested sewage sludge is circu-
lated through the aerobic biological wastewater treat-
ment process for as long as 30 days. In these cases,
the sewage sludge entering the aerobic digester is al-
ready partially digested, which makes it difficult to dem-
onstrate the 38 percent reduction required by Option 1;
Option 4 provides an alternative to the percent solids
method for demonstrating vector attraction reduction.
The oxygen uptake rate depends on the conditions of
the test and, to some degree, on the nature of the
original sewage sludge before aerobic treatment. It
should be noted that the SOUR method may be unreli-
able at solids content above 2 percent.
3.4.2.5 Option 5: Aerobic Processes at Greater
Than 40°C
Under this option, the sewage sludge must be treated
for 14 days or longer, during which time the temperature
must be over 40°C (104°) and the average temperature
higher than 45°C (113°F). This option applies primarily
to composted sewage sludge, which generally contains
substantial amounts of partially decomposed organic
bulking agents.
This option can be applied to sewage sludge from other
aerobic processes, such as aerobic digestion, but other
approaches for demonstrating compliance (e.g., those
described in Options 3 and 4) are likely to be easier to
meet for these types of sewage sludge.
3.4.2.6 Option 6: Addition of Alkali
Under this option, sewage sludge is considered to be
adequately reduced in vector attraction if sufficient alkali
is added to:
• Raise the pH to at least 12.
• Maintain a pH of at least 12 without addition of more
alkali for 2 hours.
• Maintain a pH of at least 11.5 without addition of more
alkali for an additional 22 hours.
The conditions required under this option are intended
to ensure that the sewage sludge can be stored for at
least several days at the treatment works, transported,
and then land applied without the pH falling to the point
where putrefaction occurs and vectors are attracted.
3.4.2.7 Option 7: Moisture Reduction of Sewage
Sludge Containing No Unstabilized Solids
Under this option, sewage sludge vector attraction is
considered to be reduced if the sewage sludge does not
21
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contain unstabilized solids generated during primary
wastewater treatment and if the solids content of the
sewage sludge is greater than or equal to 75 percent
before the sewage sludge is mixed with other materials.
Thus, the reduction must be achieved by removing
water, not by adding inert materials.
It is important that the sewage sludge meeting Option 7
not contain unstabilized solids because the partially de-
graded food scraps likely to be present in such sewage
sludge would attract birds, some mammals, and possi-
bly insects, even if the solids content of the sewage
exceeded 75 percent. Additionally, steps should be
taken to prevent exposure of stored sewage sludge to
high humidity, which could cause its outer surface to
equilibrate to a lower solids content and attract vectors.
3.4.2.8 Option 8: Moisture Reduction of Sewage
Sludge Containing Unstabilized Solids
Vector attraction of any sewage sludge is considered to
be adequately reduced if the solids content of the sludge
is increased to 90 percent or greater. This extreme
desiccation deters vectors in all but the most unusual
situations. The solids increase must be achieved by
removal of water and not by dilution with inert solids.
Drying to this extent severely limits biological activity
and strips off or decomposes the volatile compounds
that attract vectors.
3.4.2.9 Option 9: Injection of Sewage Sludge
Vector attraction reduction can be demonstrated by in-
jecting the sewage sludge below the ground. Under this
option, no significant amount of the sewage sludge can
be present on the land surface within 1 hour after injec-
tion. If the sludge is Class A with respect to pathogens,
it must be injected within 8 hours after discharge from
the pathogen-reduction process; special restrictions ap-
ply to Class A sewage sludge because it is a medium
for regrowth, and after 8 hours pathogenic bacteria may
rapidly increase.
Injection of sewage sludge beneath the soil places a bar-
rier of earth between the sewage sludge and vectors. The
soil quickly removes water from the sewage sludge, which
reduces the mobility and odor of the sewage sludge.
3.4.2.10 Option 10: Incorporation of Sewage
Sludge into the Soil
Under this option, sewage sludge applied to the land
surface must be incorporated into the soil within 6 hours.
If the sewage sludge is Class A with respect to patho-
gens, the time between processing and application must
not exceed 8 hours.
When applied at agronomic rates, the loading of sewage
sludge solids typically is approximately 1/200th or less
of the mass of soil in the plow layer. If mixing is reason-
ably good, the dilution of sewage sludge in the soil
surface is equivalent to that achieved with soil injection.
Initial vector attraction will diminish and be virtually elimi-
nated when the sewage sludge is mixed with the soil.
3.5 Frequency of Monitoring
The Part 503 rule requires that pollutant concentrations
(for metals), pathogen densities, and vector attraction
reduction be monitored and analyzed when sewage
sludge is land applied. Monitoring is intended to ensure
that the land-applied sewage sludge meets applicable
criteria after its quality has been initially demonstrated.
Part 503 specifies how often sewage sludge must be
monitored and lists the analytical methods to be used
for analyzing different types of samples. The frequency
of monitoring requirements range from 1 to 12 times per
year, depending on the amount of sewage sludge (in
metric tons, dry-weight basis) applied to a site. Require-
ments for monitoring must be met regardless of which
approaches are used for meeting pollutant limits and
pathogen and vector attraction reduction requirements.
Frequency of monitoring requirements are summarized
in Table 3-15. For frequency of monitoring requirements
for stored sewage sludge, contact the permitting authority.
3.6 Recordkeeping and Reporting
The person who prepares sewage sludge for land appli-
cation must provide information necessary to demon-
strate compliance with the Part 503 rule to the land
applier, and the person who applies the sewage sludge
to the land is responsible for obtaining from the preparer
information necessary to demonstrate compliance with
the rule. For a discussion of specific Part 503 record-
keeping and reporting requirements, see Chapter 15.
3.7 Sewage Sludge Quality and the Part
503 Requirements
The Part 503 requirements that must be complied with
depend on the quality of the sewage sludge, in terms of
pollutants, pathogen levels, and vector attraction reduc-
tion control. These quality differences are discussed
below and are summarized in Table 3-16.
3.7.1 Exceptional Quality (EQ) Sewage Sludge
Sewage sludge that meets the Part 503 ceiling concen-
tration limits, pollutant concentration limits, one of the
Class A pathogen reduction alternatives, and one of the
vector attraction reduction options described above can
be considered "exceptional quality" (EQ) sewage sludge.3
Sewage sludge meeting these EQ requirements are not
The sewage sludge quality designation "exceptional quality" is
based on interpretations of the Part 503 rule, which does not explic-
itly use this term.
22
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Table 3-15. Frequency of Monitoring for Pollutants, Pathogen Densities, and Vector Attraction Reduction
Amount of Sewage Sludge (U.S. tons)
Amounts of Sewage Sludge3
(metric tons per 365-day period)
Greater than zero but less than 290
Equal to or greater than 290 but
less than 1 ,500
Equal to or greater than 1 ,500 but
less than 15,000
Equal to or greater than 1 ,5000
Ave. per day
>0 to <0.85
0.85 to <4.5
4.5 to <45
>45
per 365 days
>0 to <320
320 to <1 ,650
1,650to <1 6,500
>1 6,500
Frequency
Once per year
Once per quarter
(4 times per year)
Once per 60 days
(6 times per year)
Once per month
(12 times per year)
Either the amount of bulk sewage sludge applied to the land or the amount of sewage sludge received by a person who prepares sewage
sludge for sale or give-away in a bag or other container for application to the land (dry-weight basis).
Table 3-16. Summary of Part 503 Requirements for Different Types of Sewage Sludge
Type of
Sewage
Sludge3
"Exceptional
Quality"
(Bag or Bulk)
Pollutant
Concentration
(Bulk Only)
CPLR
(Bulk Only)
APLR
(Bag Only)
Ceiling Other
Concentration Pollutant
Limit Limits
Yes Pollutant
Concentration
Limits
Yes Pollutant
Concentration
Limits
Yes Cumulative
Pollutant
Loading
Rates
(CPLRs)
Yes Annual
Pollutant
Loading
Rates
(APLRs)
Vector
Pathogen Attraction
Class Reduction
A 1 of
Options
1-8b
B 1 of
Options
1-10
A or B 1 of
Options
1-10
A 1 of
Options
1-8
Siting
Restrictions
No
Yes
No if
Pathogen
Class A
Yes if
Pathogen
Class B
No
General
Requirements,
Management
Practices
Nob
Yes
Yes
Yesc
Track
Added
Pollutants
No
No
Yes
No
All sewage sludge must also meet Part 503 frequency of monitoring requirements and recordkeeping and reporting requirements.
b If sewage sludge instead follows vector attraction reduction options 9 or 10 (incorporation or injection), the sewage sludge must also meet
Part 503 general requirements and management practices, and would not be considered "exceptional quality" sewage sludge.
c Only two general requirements and a management practice requirement for labeling must be met.
subject to Part 503's land application general require-
ments and management practices. EQ sewage sludge
can be applied as freely as any other fertilizer or soil
amendment to any type of land (unless EPA or the
director of an EPA-approved state sludge program de-
termines that in a particular case, when bulk sewage
sludge is land applied, the Part 503 general require-
ments or management practices are needed to protect
public health and the environment). Although the Part
503 rule does not require EQ sewage sludge to be
applied at the agronomic rate for nitrogen (which is a
requirement for sewage sludge not meeting EQ require-
ments), for good management EQ sewage sludge, like
any type of fertilizer, also should be applied at the agro-
nomic rate, which supplies the nitrogen needs of the
crop or vegetation grown on the site and protects ground
water.
To achieve EQ sewage sludge quality, the user or
preparer of sewage sludge must:
• Not exceed the Part 503 ceiling concentration limits
and pollutant concentration limits for regulated metals
(Table 3-4).
• Meet one of the six Part 503 Class A pathogen re-
duction alternatives (Table 3-6) and required bacterial
monitoring (Table 3-7).
• Meet one of the first eight Part 503 vector attraction
reduction options (Table 3-14).
• Comply with the Part 503 frequency of monitoring
(Table 3-15) and recordkeeping/reporting require-
ments (see Chapter 15).
23
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The Part 503 general requirements and management
practices do not apply to EQ sewage sludge unless they
are deemed necessary for bulk sewage sludge, as dis-
cussed above.
3.7.2 Pollutant Concentration (PC) Sewage
Sludge
"Pollutant Concentration" (PC) sewage sludge meets
the same low pollutant limits as EQ sewage sludge, but
usually meets Class B rather than Class A pathogen
reduction requirements. Sewage sludge meeting Class
A pathogen reduction requirements and vector attraction
options 9 or 10 (which do not qualify as EQ vector
requirements) also is PC sewage sludge. If PC sewage
sludge is Class B pathogen status, it must be land
applied according to specific site restrictions discussed
in Table 3-11 to prevent exposure to the sewage sludge.
Sewage sludge that meets PC criteria can be applied to
all types of land, except lawns and home gardens, if
these site restrictions are observed. To achieve PC sew-
age sludge quality, the sewage sludge must:
• Not exceed the Part 503 ceiling concentration limits
and pollutant concentration limits for regulated metals
(Table 3-4).
• Meet one of three Part 503 Class B pathogen reduc-
tion alternatives (Table 3-6) and Class B site restric-
tions (Table 3-11).
• Meet one of 10 applicable Part 503 vector attraction
reduction options (Table 3-14).
• Comply with the Part 503 frequency of monitoring
(Table 3-15) and recordkeeping/reporting require-
ments (see Chapter 15).
• Comply with certain Part 503 general requirements
(Table 3-17) and management practices (Table 3-5).
3.7.3 Cumulative Pollutant Loading Rate
(CPLR) Sewage Sludge
"CPLR" sewage sludge must meet more Part 503 re-
quirements than EQ or PC sewage sludge. These re-
quirements, such as tracking of cumulative metal
loadings, ensures adequate protection of public health
and the environment. CPLR sewage sludge users or
preparers must:
• Not exceed the Part 503 ceiling concentration limits
and cumulative pollutant loading rate (CPLR) limits
for regulated metals (Table 3-4) when the sewage
sludge is land applied in bulk.
• Meet either Part 503 Class A or Class B pathogen
reduction requirements (Table 3-6) and related re-
quirements (either Table 3-7 or Table 3-11).
• Meet one of 10 Part 503 vector attraction reduction
options (Table 3-14).
• Comply with Part 503 frequency of monitoring (Table
3-15) and recordkeeping/reporting requirements (see
Chapter 15).
• Comply with certain Part 503 general requirements
(Table 3-17) and management practices (Table 3-5).
3.7.4 Annual Pollutant Loading Rate (APLR)
Sewage Sludge
"APLR" sewage sludge, which pertains only to sewage
sludge sold or given away in a bag or other container for
application to land ("bagged" sewage sludge), must
meet Class A pathogen reduction requirements and one
of the vector attraction reduction treatment options.
These provisions are required because of the high po-
tential for human contact at sites where bagged sewage
sludge is likely to be applied (i.e., public contact sites
such as parks). APLR sewage sludge users or preparers
must:
• Not exceed the Part 503 ceiling concentration limits
and annual pollutant loading rate (APLR) limits for
regulated metals (Table 3-4) when the sewage sludge
is placed in a bag or other container, as defined in
Part 503, for sale or given away for application to the
land.
• Meet Part 503 Class A pathogen reduction require-
ments (Table 3-6) and required bacterial monitoring
(Table 3-7).
• Meet one of the first eight Part 503 vector attraction
reduction options (Table 3-14).
• Meet the Part 503 management practice that requires
a label or information sheet that lists data specified
in Part 503 (Table 3-5).
• Meet the Part 503 frequency of monitoring (Table
3-15) and recordkeeping/reporting requirements (see
Chapter 15).
• Meet the Part 503 general requirements (Part
503.12(a) and (e)(i)).
The Part 503 labelling provision requires that the
preparer of APLR sewage sludge provide the applier
with allowable application rate information, either on a
label or in a handout (usually based on the nutrient
content of the sewage sludge). This information is based
on the preparer's calculation of the annual whole sludge
application rate (AWSAR) (Table 3-18). The preparer/
manufacturer also provides the applier with information
on the nutrient value of the bagged sewage sludge. The
recommended application rate helps ensure that the
sewage sludge is applied at the appropriate agronomic
rate to minimize the amount of excess nitrogen that
passes below the root zone and into ground water.
24
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Table 3-17. Part 503 Land Application General Requirements
For EQ Sewage Sludge
None (unless set by EPA or state permitting authority on a
case-by-case basis for bulk sewage sludge to protect public health
and the environment).
For PC and CPLR Sewage Sludge
The prepare!3 must notify and provide information necessary to
comply with the Part 503 land application requirements to the
person who applies bulk sewage sludge to the land.
The preparer who provides sewage sludge to another person who
further prepares the sewage sludge for application to the land
must provide this person with notification and information
necessary to comply with the Part 503 land application
requirements.
The preparer must provide written notification of the total nitrogen
concentration (as N on a dry-weight basis) in bulk sewage sludge
to the applier of bulk sewage sludge to agricultural land, forests,
public contact sites, or reclamation sites.
The applier of sewage sludge must obtain information necessary
to comply with the Part 503 land application requirements, apply
sewage sludge to the land in accordance with the Part 503 land
application requirements, and provide notice and relevant
information to the owner or lease holder of the land on which
sewage sludge is applied.
Out-of-State Use
The preparer must provide written notification (prior to the initial
application of the bulk sewage sludge by the applier) to the
permitting authority in the state where sewage sludge is proposed
to be land applied when bulk sewage sludge is generated in one
state (the generating state) and transferred to another state (the
receiving state) for application to the land. The notification must
include:
• the location (either street address or latitude and longitude) of
each land application site;
• the approximate time period the bulk sewage sludge will be
applied to the site;
• the name, address, telephone number, and National Pollutant
Discharge Elimination System (NPDES) permit number for both
the preparer and the applier of the bulk sewage sludge; and
• additional information or permits in both states, if required by the
permitting authority.
Additional Requirements for CPLR Sewage Sludge
The applier must notify the permitting authority in the state where
bulk sewage sludge is to be applied prior to the initial application
of the sewage sludge. This is a one-time notice requirement for
each land application site each time there is a new applier. The
notice must include:
• the location (either street address or latitude and longitude) of the
land application site; and
• the name, address, telephone number, and NPDES permit
number (if appropriate) of the person who will apply the bulk
sewage sludge.
The applier must obtain records (if available) from the previous
applier or landowner that indicate the amount of each CPLR
pollutant in sewage sludge that have been applied to the site since
July 20, 1993. In addition:
• when CPLR sewage sludge was previously applied since July 20,
1993 to the site and cumulative amounts of regulated pollutants
are known, the applier must use this information to determine the
additional amount of each pollutant that can be applied to the site
in accordance with the CPLRs in Table 3-4;
• the applier must keep the previous records and also record the
additional amount of each pollutant he or she is applying to
the site; and
• when CPLR sewage sludge was previously applied to the site
and cumulative amounts of regulated pollutants are not known, no
additional sewage sludge meeting CPLRs can be applied to that
site. However, EQ or PC sewage sludge could be applied.
If sewage sludge meeting CPLRs has not been applied to the site
in excess of the limit since July 20, 1993, the CPLR limit for each
pollutant in Table 3-4 will determine the maximum amount of each
pollutant that can be applied if the applier keeps a record of the
amount of each pollutant in sewage sludge applied to any given
site.
The applier must not apply additional sewage sludge under the
cumulative pollutant loading concept to a site where any of the
CPLRs have been reached.
The preparer is either the person who generates the sewage sludge or the person who derives a material from sewage sludge. This includes
the person who prepares sewage sludge for sale or give-away in a bag or other container for application to the land.
25
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Table 3-18. Procedure to Determine the Annual Whole Sludge Application Rate for Sewage Sludge Sold or Given Away in a Bag
or Other Container for Application to Land
1. Analyze a sample of the sewage sludge to determine the concentration of each of the 10 regulated metals in the sewage sludge.
2. Using the pollutant concentrations from Step 1 and the APLRs from Table 3-4, calculate an AWSAR for each pollutant using the following
equation:
where:
AWSAR = Annual whole sludge application rate (dry metric tons of sewage sludge/hectare/year)
APLR = Annual pollutant loading rate (in Table 3-4) (kg of pollutant/ha/yr)
C= Pollutant concentration (mg of pollutant/kg of sewage sludge, dry weight)
0.001 = A conversion factor
3. The AWSAR for the sewage sludge is the lowest AWSAR calculated for each pollutant in Step 2.
Example:
a. Sewage sludge to be applied to land is analyzed for each of the 10 metals regulated in Part 503. Analysis of the sewage sludge
indicates the pollutant concentration in the second column of the table below.
b. Using these test results and the APLR for each pollutant from Table 3-4, the AWSAR for all the pollutants are calculated as shown in the
fourth column of the table below.
c. The AWSAR for the sewage sludge is the lowest AWSAR calculated for all 10 metals. In our example, the lowest AWSAR is for copper
at 20 metric tons of sewage sludge/hectare/year. Therefore, the AWSAR to be used for this sewage sludge is 20 metric tons per
hectare/year. The 20 metric tons of sewage sludge/hectare is the same as 41 0 pounds of sewage sludge/1 ,000 square feet (20 metric tons
x 2,205 Ib per metric ton/107,600 square feet per hectare). The AWSAR on the label or information sheet would have to be equal to or less
than 410 pounds per 1,000 square feet.
AWSAR =
Metal
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
oevvdye oiuuye
Concentrations
(milligrams/kilogram)
10
10
1,000
3,750
150
2
—
100
15
2,000
«ri_r^
(kilograms/
hectare/year)
2.0
1.9
150
75
15
0.85
—
21
5.0
140
Cone, in Sewage Sludge (0.001)
2/(10 x 0.001)
1.97(10x0.001)
1507(1,000x0.001)
757(3,750x0.001)
157(150x0.001)
0.857(2x0.001)
—
217(100 x 0.001)
57(15 x 0.001)
140/(2,000x 0.001)
;u 11. iuii:>/ iicuidic/ ye
= 200
= 190
= 150
= 20
= 100
= 425
= 210
= 333
= 70
Annual pollutant loading rates from Table 3-4 of this guide and Table 4 of the Part 503 rule. The APLR for molybdenum does not have to be
met while EPA is reconsidering this value.
3 8 References u-s- EPA- 1994- A P'ain English guide to the EPA Part 503 biosolids
rule. EPA/832/R-93/003. Washington, DC.
When an NTIS number is cited in a reference, that u.s. EPA. I992a. Technical support document for land application of
document is available from: sewage sludge, Vol. 1. EPA/822/R-93/018a (NTIS PB93110575).
National Technical Information Service Washington, DC.
5285 Port Royal Road u s ERA 1992b Environmental regulations and technology: Control
Springfield, VA 22161 of pathogens and vector attraction in sewage sludge. EPA/625/R-
703-487-4650 92/013. Washington, DC.
26
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Chapter 4
Characteristics of Sewage Sludge
4.1 Introduction
Determining the suitability of sewage sludge for land ap-
plication by characterizing its properties is a necessary first
step in planning and designing a land application system.
The composition of sewage sludge will have important
bearing on the following design decisions:
• Whether the sewage sludge can be cost-effectively
applied to land.
• Which land application practice (i.e., application to
agricultural, forest, reclamation or public contact
sites) is technically feasible.
• The quantity of sewage sludge to be applied per unit
area, both annually and cumulatively.
• The degree of regulatory control and system moni-
toring required.
Important properties of sewage sludge that need to be
characterized include:
• Quantity
• Total solids content
• Volatile solids content
• pH
• Organic matter
• Pathogens
• Nutrients
• Metals
• Organic chemicals
• Hazardous pollutants, if any
Sewage sludge composition depends principally on the
characteristics of the wastewater influent entering the
wastewater treatment works and the treatment proc-
esses used. Generally, the more industrialized a com-
munity is, the greater the possibility that heavy metals
may pose a potential problem for land application of
sewage sludge. Industrial pretreatment requirements
(40 CFR Part 403) and pollution prevention programs,
as well as advances in wastewater and sewage sludge
treatment processes, generally have reduced the levels
of pollutants in the final sewage sludge leaving a treat-
ment works. Figure 4-1 shows the basic wastewater and
sewage sludge generation and treatment process.
This chapter describes the properties of sewage sludge
to be characterized, the different types of sewage sludge
(which exhibit different characteristics), and the effects
that wastewater and sewage sludge treatment proc-
esses and pretreatment have on sewage sludge
characteristics. The information provided is intended
primarily for illustrative purposes. While the data are
useful in preliminary planning, analysis of the actual
sewage sludge to be land-applied is necessary for de-
sign purposes. The chemical composition of sewage
sludge may vary greatly between wastewater treatment
works and also overtime at a single plant. This variabil-
ity in sewage sludge composition underscores the need
for a sound sampling program (e.g., analysis of a sub-
stantial number of sewage sludge samples over a period
of 2 to 6 months or longer) to provide a reliable estimate
of sewage sludge composition. Sampling is discussed
in Chapters 6 and 13.
4.2 Sewage Sludge Quantity
The amount of sewage sludge to be land applied will
affect site evaluation and design in several important
ways, including land area needs, size of transportation
equipment and storage facilities, and cost. Quantities of
sewage sludge available also will affect the selection of
land application practices (i.e., application at agricul-
tural, forest, reclamation or public contact sites), as well
as application rates and operating schedules.
Sewage sludge quantity can be measured in two ways:
the volume of the wet sewage sludge, which includes
the water content and solids content, or the mass of the
dry sewage sludge solids. Sewage sludge volume is
expressed as gallons (liters) or cubic meters, while
sludge mass usually is expressed in terms of weight, in
units of dry metric tons (tonnes). Because the water
content of sewage sludge can be high and quite vari-
able, the mass of dry sludge solids is often used to
compare sewage sludges with different proportions of
water (U.S. EPA, 1984).
27
-------
SEWAGE SLUDGE
DOMESTIC
SEWAGE
GENERATION
INDUSTRIAL
WASTEWATER
GENERATION
TREATED* USE
SEWAGE
SLUDGE
Land Application
• Agricultural land
• Strip-mined land
• Forests
• Plant nurseries
• Cemeteries
• Parks, gardens
• Lawns and home
gardens
DOMESTIC SEPTAGE
RAW
) SEPTAGE\
r "v
SEPTIC TANKS
PUMPING
AND
HAULING
COTREATMENT
WITH
WASTEWATER
AND/OR
SEWAGE SLUDGE
SEPTAGE
TREATMENT
TREATED
SEWAGE
SLUDGE/
SEPTAGE
Figure 4-1. Generation, treatment, use, and disposal of sewage sludge and domestic septage.
28
-------
Key factors affecting sewage sludge volume and mass
are wastewater sources and wastewater and sludge
treatment processes. For example, industrial contribu-
tions to wastewater influent streams can significantly
increase the sewage sludge quantity generated from a
given amount of wastewater. Also, higher degrees
of wastewater treatment generally increase sewage
sludge volume. In addition, as shown in Table 4-1, some
sewage sludge treatment processes reduce sewage
sludge volume, some reduce sewage sludge mass, and
some increase sewage sludge mass while improving
other sewage sludge characteristics (U.S. EPA, 1984).
4.3 Total Solids Content
The total solids (TS) content of sewage sludge includes
the suspended and dissolved solids and is usually ex-
pressed as the percent of total solids present in a sew-
age sludge. TS can affect the potential land application
system design in several ways, including:
• Size of transportation and storage systems—The
higher the solids content, the lower the volume of
sewage sludge that will have to be transported and
stored because less water will need to be handled.
• Mode of transport—Different types of transportation
to the land application site (e.g., trucks, pipelines) will
be used depending on the solids content of the sew-
age sludge to be applied (see Chapter 14).
• Application method and equipment—The method of
sewage sludge application (e.g., surface spreading,
injection, spray irrigation) and the type of application
equipment needed will vary depending on the solids
content of the sewage sludge (see Chapter 14).
• Storage method—Different storage methods will be
used depending on solids content (e.g., tanks for
liquid sewage sludge versus stockpiles for dewatered
sewage sludge).
In general, it is less expensive to transport sewage
sludge with a high solids content (dewatered sewage
sludge) than to transport sewage sludge with a low
solids content (liquid sewage sludge). This cost savings
in transport should be weighed against the cost of de-
watering the sewage sludge. Typically, liquid sewage
sludge has a solids content of 2 to 12 percent solids,
while dewatered sewage sludge has a solids content of
12 to 40 percent solids (including chemical additives).
Dried or composted sewage sludge typically has a sol-
ids content over 50 percent.
TS content depends on the type of sewage sludge
(primary, secondary, or tertiary, as discussed in Section
4.12), whetherthe sewage sludge has been treated prior
to land application, and how it was treated. Treatment
processes such as thickening, conditioning, dewatering,
composting, and drying can lower water content and
thus raise the percent solids. The efficiency of these
treatment processes, however, can vary substantially
from time to time, producing sewage sludge with sub-
stantially lower solids content than anticipated. Land
application sites, therefore, should be flexibly designed
to accommodate the range of variations in sewage
sludge solids content that may occur as a result of
variations in the efficiency of the wastewater and sew-
age sludge treatment processes. Without this flexibility,
operational problems could result at the site.
4.4 Volatile Solids Content
Sludge volatile solids (VS) are organic compounds that
are reduced when the sludge is heated to 550°C
(1,022°F) under oxidizing conditions. The VS content of
sludge provides an estimate of the organic content of
the material. VS content is most often expressed as the
percent of total solids that are volatile solids. VS is an
important determinant of potential odor problems at land
application sites. Reduction of VS is one option in the
Part 503 regulation for meeting vector attraction reduc-
tion requirements (see Chapter 3). Most unstabilized
sewage sludge contains 75 percent to 85 percent VS on
a dry weight basis. A number of treatment processes,
including anaerobic digestion, aerobic digestion, alkali
stabilization, and composting, can be used to reduce
sludge VS content and thus the potential for odor. An-
aerobic digestion—the most common method of sludge
stabilization—generally biodegrades about 50 percent
of the volatile solids in a sewage sludge.
4.5 pH
The pH of sewage sludge can affect crop production at
land application sites by altering the pH of the soil and
influencing the uptake of metals by soil and plants.
Pathogen levels and vector control are the major rea-
sons for pH adjustment of sewage sludge. Low pH
sludge (less than approximately pH 6.5) promotes
leaching of heavy metals, while high pH sludge (greater
than pH 11) kills many bacteria and, in conjunction with
soils of neutral or high pH, can inhibit movement of
heavy metals through soils. Some of the Part 503 patho-
gen reduction alternatives include raised pH levels (see
Chapters).
4.6 Organic Matter
The relatively high level of organic matter in sewage
sludge allows the sludge to be used as a soil conditioner
to improve the physical properties of soil (e.g., increased
water infiltration and water-holding capacity). The soil
conditioning properties of sewage sludge are especially
useful at reclamation sites such as mine spoils.
29
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Table 4-1. Effects of Sewage Sludge Treatment Processes on Land Application Practices (U.S. EPA, 1984)
Treatment Process and Definition Effect on Sewage Sludge Effect on Land Application Practices
Thickening: Low-force separation of
water and solids by gravity, flotation, or
centrifugation. (Sewage sludge thickeners
may also be used as flow equalization
tanks to minimize the effect of sewage
sludge quantity fluctuations on subsequent
treatment processes.)
Digestion (Anaerobic and Aerobic):
Biological stabilization of sewage sludge
through conversion of some of the organic
matter to water, carbon dioxide, and
methane. (Digesters may also be used to
store sewage sludge to provide greater
flexibility for the treatment operation and
to homogenize sewage sludge solids to
facilitate subsequent handling procedures.)
Alkali Stabilization: Stabilization of
sewage sludge through the addition of
alkali.
Conditioning: Alteration of sewage
sludge properties to facilitate the
separation of water from sewage sludge.
Conditioning can be performed in many
ways, e.g., adding inorganic chemicals
such as lime and ferric chloride; adding
organic chemicals such as polymers;
mixing digested sewage sludge with water
and resettling (elutriation); or briefly raising
sewage sludge temperature and pressure
(heat treatment). Thermal conditioning
also causes disinfection.
Dewatering: High-force separation of
water and solids. Dewatering methods
include vacuum filters, centrifuges, filter
presses, belt presses, lagoons, and sand
drying beds.
Composting: Aerobic process involving
the biological stabilization of sewage
sludge in a windrow, aerated static pile,
or vessel.
Heat Drying: Application of heat to ki
pathogens and eliminate most of the
water content.
Increase solids concentration of sewage
sludge by removing water, thereby
lowering sewage sludge volume. May
provide a blending function in combining
and mixing primary and secondary
sewage sludges.
Reduces the volatile and biodegradable
organic content and the mass of sewage
sludge by converting it to soluble material
and gas. May reduce volume by
concentrating solids. Reduces pathogen
levels and controls putrescibility and odor.
Raises sewage sludge pH. Temporarily
decreases biological activity. Reduces
pathogen levels and controls putrescibility.
Increases the dry solids mass of the
sewage sludge. Because pH effects are
temporary, decomposition, leachate
generation, and release of gas, odors,
and heavy metals may occur over time.
Improves sewage sludge dewatering
characteristics. Conditioning may increase
the mass of dry solids to be handled
without increasing the organic content of
the sewage sludge. Conditioning may also
improve sewage sludge compactability
and stabilization. Generally, polymer-
treated sewage sludges tend to be sticky,
slick, and less workable than other
sewage sludges. Some conditioned
sewage sludges are corrosive.
Increases solids concentration of sewage
sludge by removing much of the entrained
water, thereby lowering sewage sludge
volume. Dewatering may increase sewage
sludge solids to 15% to 40% for organic
sewage sludges and 45% or more for
some inorganic sewage sludges. Some
nitrogen and other soluble materials are
removed with the water. Improves ease of
handling by converting liquid sewage
sludge to damp cake. Reduces fuel
requirements for heat drying.
Lowers biological activity. Can destroy
most pathogens. Degrades sewage
sludge to a humus-like material. Increases
sewage sludge mass due to addition of
bulking agent.
Disinfects sewage sludge. Destroys most
pathogens. Slightly lowers potential for
odors and biological activity.
Lowers sewage sludge transportation
costs for all practices (e.g, agricultural,
forests, reclamation sites, public contact
sites).
Reduces sewage sludge quantity.
High pH of alkali-stabilized sewage sludge
tends to immobilize heavy metals in
sewage sludge as long as the pH levels
are maintained.
Polymer-treated sewage sludges may
require special operational considerations
at the land application site.
Reduces land requirements and lowers
sewage sludge transportation costs for all
practices.
Excellent soil conditioning properties.
Significant storage usually needed. May
contain lower nutrient levels than less
processed sewage sludge.
Greatly reduces volume of sewage sludge.
30
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4.7 Pathogens
Potential disease-causing microorganisms known as
pathogens, including bacteria, viruses, protozoa, and
eggs of parasitic worms, are often present in municipal
wastewater and raw sewage sludge. Pathogens also
are present in domestic septage. Pathogens can pre-
sent a public health hazard if they are transferred to food
crops grown on land to which sewage sludge or domes-
tic septage is applied, contained in runoff to surface
waters from land application sites, or transported away
from the site by vectors such as insects, rodents, and
birds. For this reason, Part 503 specifies pathogen re-
duction and vector attraction reduction requirements
that must be met by sewage sludge applied to land
application sites. Table 4-2 illustrates the different types
of pathogens typically found in sewage sludge and do-
mestic septage.
Generally, sewage sludge intended for land application
is stabilized by chemical or biological processes (see
Section 4.13). Table 4-3 shows typical levels of some
pathogens in unstabilized and stabilized sewage sludge.
Stabilization greatly reduces the number of pathogens
in sewage sludge, including bacteria, parasites, proto-
zoa, and viruses (Sagik et al., 1979), as well as odor
potential. Nevertheless, even stabilized sewage sludge
will usually contain some pathogens; thus the Part 503
regulation requires that specific processes to reduce
pathogen levels be undertaken prior to land application
and that site restrictions for certain types of sewage
sludge be followed. The Part 503 pathogen and vector
attraction reduction requirements serve to protect oper-
ating personnel, the general public, crops intended for
human consumption, ground water, and surface water
from potential contamination by unacceptable levels of
pathogens. Part 503 requirements also are designed to
ensure that regrowth of bacteria does not occur prior to
use or disposal. A summary of the Part 503 pathogen
and vector attraction reduction requirements is pre-
sented in Chapter 3. For more detailed discussions of
Table 4-3. Typical Pathogen Levels in Unstabilized and
Anaerobically Digested Liquid Sludges (U.S. EPA, 1979)
Typical Typical
Concentration in Concentration in
Unstabilized Anaerobically
Sludge Digested Sludge
Pathogen (No./100 milliliters) (No./100 milliliters)
Table 4-2. Principal Pathogens of Concern in Municipal
Wastewater and Sewage Sludge
Organism
Disease/Symptoms
Virus
Fecal Coliform Bacteria3
Salmonella
Ascaris lumbricoides-
Helminth
2,500
1,000
8
200
- 70,000
,000,000
,000
- 1 ,000
100
30,000
3
0
- 1 ,000
- 6,000,000
-62
- 1 ,000
Bacteria
Salmonella sp.
Shigella sp.
Vibrio cholerae
Campylobacter jejuni
Escherichia coli
(pathogenic strains)
Enteric Viruses
Hepatitis A virus
Norwalk and Norwalk-like
viruses
Rotaviruses
Enteroviruses
Polioviruses
Coxsackieviruses
Echoviruses
Reovirus
Astroviruses
Calciviruses
Protozoa
Cryptosporidium
Entamoeba histolytica
Giardia lamblia
Balantidium coli
Toxoplasma gondi
Helminth Worms
Ascaris lumbricoides
Ascaris suum
Trichuris trichiura
Toxocara canis
Taenia saginata
Taenia solium
Necator americanus
Hymenolepis nana
Salmonellosis (food poisoning),
typhoid fever
Bacillary dysentery
Cholera
Gastroenteritis
Gastroenteritis
Infectious hepatitis
Epidemic gastroenteritis with severe
diarrhea
Acute gastroenteritis with severe
diarrhea
Poliomyelitis
Meningitis, pneumonia, hepatitis, fever,
cold-like symptoms, diarrhea, etc.
Meningitis, paralysis, encephalitis, fever,
cold-like symptoms, diarrhea, etc.
Respiratory infections, gastroenteritis
Epidemic gastroenteritis
Epidemic gastroenteritis
Gastroenteritis
Acute enteritis
Giardiasis (including diarrhea,
abdominal cramps, weight loss)
Diarrhea and dysentery
Toxoplasmosis
Digestive and nutritional
disturbances, abdominal pain,
vomiting, restlessness
May produce symptoms such as
coughing, chest pain, and fever
Abdominal pain, diarrhea, anemia,
weight loss
Fever, abdominal discomfort, muscle
aches, neurological symptoms
Nervousness, insomnia, anorexia,
abdominal pain, digestive
disturbances
Nervousness, insomnia, anorexia,
abdominal pain, digestive
disturbances
Hookworm disease
Taeniasis
1 Although not pathogenic, they are frequently used as indicators.
31
-------
pathogens that may be present in sewage sludge and
pathogen and vector attraction reduction processes, see
other EPA documents (U.S. EPA, 1992a, 1994).
Following land application, bacterial pathogens gener-
ally die off to negligible numbers (99 percent die-off) in
12 days (Salmonella sp.) or 18 days (fecal coliform) at
a temperature of 15°C (EPA, 1992b, based on EPA,
1987). Viruses commonly survive a maximum of 19 days
(surface application) at 15°C (EPA, 1987; U.S. EPA,
1992b). Protozoa will survive for only a few days (Kowal,
1983). Viable helminth ova densities in sewage sludge
applied to the surface of grassed plots are reduced by
more than 90 percent within 3 to 4 months; viable
helminth ova survive longer if sewage sludge is tilled into
the soil (Jakubowski, 1988). Generally, none of these
microorganisms will leach through the soil system to
pollute the receiving ground waters (Edmonds, 1979),
but instead will remain in the surface soils for the dura-
tion of their survival period. Where surface runoff occurs,
buffers should be used to filter out pathogens and pre-
vent entry into receiving water bodies.
4.8 Nutrients
Nutrients present in sewage sludge, such as nitrogen
(N), phosphorus (P), and potassium (K), among others,
are essential for plant growth and endow sewage sludge
with its fertilizing properties. Nutrient levels are key de-
terminants of sewage sludge application rates. Exces-
sive nutrient levels due to high sludge application rates
can result in environmental contamination of ground
water and surface water and should be avoided. The
Part 503 regulation requires that bulk sewage sludge be
applied to land at the agronomic rate for nitrogen at the
application site.1
Table 4-4 shows levels of nutrients typically present in
sewage sludge. Nutrient levels, however, particularly
nitrogen levels, can vary significantly, and thus analysis
should be conducted on the actual sewage sludge being
considered for land application. Typically, nutrient levels
in sewage sludge are considerably lower than those in
commercial fertilizers, especially K, which is usually less
than 0.5 percent in sewage sludge (Table 4-4). Thus,
supplemental fertilization will usually be needed along
with sewage sludge to promote optimum vegetative
growth. More sewage sludge can be applied for addi-
tional nutrients as long as the Part 503 CPLRs are not
exceeded, or the Part 503 pollutant concentration limits
are met (see Chapter 3). When the pollutant concentra-
tion limits are met, the application rate for the sewage
Table 4-4. Nutrient Levels Identified in Sewage Sludge
(Sommers, 1977; Furr et al., 1976)a
Percent13
Nutrient
Total N
NHJ-N
NOg-N
P
K
Na
Ca
Fe
Number of
Samples
191
103
43
189
192
176
193
165
Range
<0.1-17.6
5x10'4-6.76
2x10'4-0.49
<0. 1-14.3
0.02-2.64
0.01-3.07
0.1-25.0
<0.1-15.3
Median
3.30
0.09
0.01
2.30
0.30
0.24
3.9
1.1
Mean
3.90C
0.65
0.05
2.50
0.40
0.57
4.9
1.3
1 The agronomic rate is defined in Part 503 as the sewage sludge
application rate designed to provide the amount of nitrogen needed
by the crop or vegetation grown and to minimize the amount of
nitrogen in the sewage sludge that passes below the root zone of
the crop to the ground water.
3 Data are from numerous types of sludge in 15 states: Michigan,
New Hampshire, New Jersey, Illinois, Minnesota, Ohio, California,
Colorado, Georgia, Florida, New York, Pennsylvania, Texas, Wash-
ington, and Wisconsin.
b Dry solids basis.
c It is assumed that 82 percent of the total N is organic N. So: organic
N + NH4 + NO3 = TN, or: 3.2 + 0.65 + 0.05 = 3.90.
sludge is not impacted by the amount of each pollutant
in the sewage sludge.
4.8.1 Nitrogen
Nitrogen (N) may be present in sewage sludge in an
inorganic form, such as ammonium (NH4) or nitrate
(NO3), or in an organic form. The form in which N is
present in sewage sludge is a key factor in determining
how much N is available to plants, as well as the poten-
tial for N contamination of ground water. Generally, in-
organic N as NO3 is the most water-soluble form of N,
and therefore is of the most concern for ground-water
contamination because of its high mobility in most soil
types. Inorganic N in the form of NH4 can readily vola-
tilize as ammonia (NH3) when sewage sludge is applied
to the soil surface rather than incorporated or injected,
and thus may not be available to plants. Organic N must
be decomposed by soil microorganisms, or mineralized
to inorganic NH4 and NO3, before this form of N is
available for plants to use. Therefore, organic N can be
considered a slow-release form of N.
The concentrations of organic and inorganic N in sew-
age sludge are affected by the type of sludge treatment
and handling processes used. Most of the organic N in
sewage sludge is associated with the sludge solids, and
thus organic N levels are not appreciably altered by
sludge dewatering or drying procedures. In contrast, the
water-soluble inorganic forms of N and their concentra-
tions will decrease dramatically during dewatering (e.g.,
drying beds, centrifuges, presses). Some heat or air
drying processes or lime treatment will reduce NH4 be-
cause of NH3 volatilization, but will not affect NO3 levels.
32
-------
Aerobic conditions facilitate microbial conversion of
other N species to the mobile NO3 form; conversely,
anaerobic conditions inhibit conversion of NH4 to NO3
by oxidation. Usually, over 90 percent of the inorganic N
in sewage sludge will be in the form of NH4 unless
aerobic conditions have prevailed during sludge treat-
ment. For most liquid sewage sludge collected from an
anaerobic digester, essentially all the inorganic N will be
present as NH4, constituting from 25 to 50 percent of the
total N. The NH4 concentration in the liquid phase of
sludge is relatively constant at a specific treatment plant,
although treatment process such as dewatering can
substantially lower the NH4 content to less than 10
percent of the total N.
Because the inorganic N content of sewage sludge is
significantly influenced by sludge handling procedures, N
analysis should be conducted on the actual sewage sludge
that is land applied. The amount of inorganic N mineralized
in soils is affected by the extent of sludge processing (e.g.,
digestion, composting) within the sewage treatment plant
and will generally be less for well stabilized sludge.
The organic N content of sewage sludge can range from
1 to 10 percent on a dry weight basis. Organic N com-
pounds found in sludge are primarily amino acids, indi-
cating the presence of proteinaceous materials (Ryan et
al., 1973; Sommers et al., 1972). After application to
soils, microbes in the soil will decompose the organic N
compounds in sewage sludge, resulting in release of
NH4, which can then be assimilated by the crop or
vegetation being grown.
For a further discussion of nitrogen availability once
sewage sludge has been land applied, see Chapters 7,
8, and 9.
4.8.2 Phosphorous, Potassium, and Other
Nutrients
Sewage sludge contains varying concentrations of other
macro- and micronutrients required for plant growth. Some
sludge constituents, such as phosphorous (P), calcium
(Ca), magnesium (Mg), and iron (Fe), readily form insol-
uble compounds with sludge solids and thus remain at
relatively high levels in sewage sludge (Table 4-4).
Other sewage sludge constituents, such as potassium
(K) and sodium (Na), are water-soluble and are dis-
charged with the treated wastewater, unless special
advanced treatment processes are used to remove
them. Of the water-soluble constituents that do remain
in the sludge, dewatering of sludge (e.g., by centrifuges
or presses) will further reduce their concentrations in
sludge, while air or heat drying will result in increased
levels because these constituents are nonvolatile.
For a discussion of the influence of P, K, and nutrient
levels on sewage sludge application rates, see Chap-
ters 7, 8 and 9.
4.9 Metals
Sewage sludge may contain varying amounts of metals;
at low concentrations in soil, some of these metals are
nutrients needed for plant growth and are often added to
inorganic commercial fertilizers. But at high concentra-
tions, some metals may be toxic to humans, animals, and
plants. Based on an extensive risk assessment of metals
in sewage sludge, the Part 503 rule regulates 10 metals in
sewage sludge that is to be land applied, including:
• Arsenic
• Cadmium
• Chromium
• Copper
• Lead
• Mercury
• Molybdenum
• Nickel
• Selenium
• Zinc
The Part 503 risk assessment found that other metals
do not pose potential health or environmental risks at
land application sites. EPA's 1990 National Sewage
Sludge Survey (NSSS) analyzed samples of 412 pollut-
ants or analytes from 177 POTWs using at least secon-
dary treatment processes, including the 10 metals
regulated by Part 503 for land application, as shown in
Table 4-5. Chapter 3 discusses the Part 503 pollutant
limits for these 10 metals. Based on the NSSS survey,
EPA estimates that only approximately 2 percent (130
POTWs) of the 6,300 POTWs affected by Part 503
Table 4-5.
Metal
Mean Concentrations of Metals in Sewage Sludge
Compared to Part 503 Ceiling Concentration
Limits (Adapted From U.S. EPA, 1990)
Mean Concentration
(mg/kg, DW)
Part 503 Pollutant
Ceiling Concentration
Limits (mg/kg, DW)
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
9.9
6.94
119
741
134.4
5.2
9.2
42.7
5.2
1,202
75
85
3,000
4,300
840
57
75
420
100
7,500
33
-------
would not meet the regulation's "ceiling concentrations"
for metals, the minimal requirement for land application.
Metal concentrations in sewage sludge in large part
depend on the type and amount of industrial waste
discharged into the wastewater treatment system. Be-
cause metals are generally insoluble, they usually are
present at higher levels in sewage sludge than in waste-
water, and dewatering of sewage sludge has a minimal
impact on reducing metal concentrations in sewage
sludge destined for land application. Pretreatment of
industrial wastewater discharged to a sewerage system
has been effective in reducing the metals content of
sewage sludge generated at treatment works.
4.10 Organic Chemicals
Sewage sludge may also contain synthetic organic
chemicals from industrial wastes, household products,
and pesticides. Most sewage sludge contains low levels
of these chemicals and does not pose a significant
human health or environmental threat. Part 503 does not
regulate organic chemicals in sewage sludge because
the organic chemicals of potential concern have been
banned or restricted for use in the United States; are no
longer manufactured in the United States; are present
at low levels in sewage sludge based on data from EPA's
1 990 NSSS; or because the limit for an organic pollutant
identified in the Part 503 risk assessment is not ex-
pected to be exceeded in sewage sludge that is used or
disposed (U.S. EPA, 1992b).
4.11 Hazardous Pollutants (If Any)
Sewage sludge is not included on a list of specific wastes
determined to be hazardous by EPA, nor does available
data suggest that sewage sludge is likely to exhibit char-
acteristics of a hazardous waste, which include ignitability,
corrosivity, reactivity, ortoxicity. The non-hazardous nature
of sewage sludge, however, cannot be assumed.
Although sewage sludge conceivably could exhibit the
characteristics of ignitability, corrosivity, or reactivity, most
concerns about sewage sludge have focused on toxicity.
Few, if any, sewage sludges will exhibit the toxicity char-
acteristic (55 FR 11838). If, however, factors are present
indicating a possible toxicity problem (e.g., the treatment
works receives significant loadings of pollutants covered
by the test for toxicity) and the treatment works does not
have current data showing that the sludge is not hazard-
ous, it is advisable for the treatment works to test the
sewage sludge for toxicity (U.S. EPA, 1990).
The test for toxicity is the Toxicity Characteristic Leach-
ing Procedure (TCLP). This test can be used for both
sewage sludge and domestic septage. Forthe TCLP
test, concentrations of pollutants in a TCLP sewage
sludge extract are compared to regulatory levels for
tnyir.itv Tahlff 4-fi li<;t<; thp> tnyir.itv r.harar.tp>ri<;tir.
Table 4-6. Analytical Classification and
Constituent
Pesticides
Chlordane
Endrin
Heptachlor
Lindane
Methoxychlor
Toxaphene
Herbicides
2,4-D
2,4,5-TP Silvex
Volatiles
Benzene
Carbon tetrachloride
Chlorobenzene
Chloroform
1 ,2-Dichloroethane
1,1-Dichloroethylene
Methyl ethyl ketone
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl chloride
Semivolatiles
o-Cresol
m-Cresol
p-Cresol
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
2,4-Dinitrotoluene
Hexachlorobenzene
Hexachlorobutadiene
Hexachloroethane
Nitrobenzene
Pentachlorophenol
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Metals
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Limits for TCLP Constituents
Limit, mg/L
0.03
0.02
Or\r\p
.UUo
0.4
10.0
0.5
10.0
1.0
0.5
0.5
100.0
6.0
0.5
0.7
200.0
0.7
1000.0
0.5
0.2
200.0
200.0
200.0
300.0
7.5
0 1
0.02
0.5
3.0
2.0
1.0
400.0
2.0
5.0
100.0
1.0
5.0
5.0
0.2
1.0
5.0
34
-------
pollutants and their regulatory levels. If the concen-
trations of pollutants in the extract meet or exceed
these regulatory levels, the wastes are classified as
hazardous. If a sewage sludge or domestic septage
extract is deemed hazardous, land application would not
be allowed. Studies conducted by EPA's Office of Solid
Waste in 1985-86 found that none of the sewage sludge
samples tested had TCLP extract concentrations that
exceeded the (then proposed) regulatory levels. For
most pollutants, except metals, levels were non-detect-
able (U.S. EPA, 1993a).
4.12 Types of Sewage Sludge
The characteristics of sewage sludge described above
will vary depending on the type of sewage sludge gen-
erated, as discussed below.
4.12.1 Primary Sewage Sludge
Primary sewage sludge—sludge that is the result of
primary wastewater treatment and has not undergone
any sludge treatment process—usually contains from 93
to 99.5 percent water, as well as solids and dissolved
substances that were present in the wastewater or were
added during the wastewater treatment process (U.S.
EPA, 1984). Primary wastewater treatment removes the
solids (sludge) that settle out readily from the wastewa-
ter. Usually the water content of this sludge can be easily
reduced by thickening or dewatering.
4.12.2 Secondary Sewage Sludge
Secondary wastewater treatment generally involves a
primary clarification process followed by biological treat-
ment and secondary clarification (U.S. EPA, 1990).
Sewage sludge generated by secondary wastewater
treatment processes, such as activated biological sys-
tems and trickling filters, has a low solids content (0.5
percent to 2 percent) and is more difficult to thicken and
dewaterthan primary sewage sludge.
4.12.3 Tertiary Sewage Sludge
Tertiary sewage sludge is produced by advanced waste-
water treatment processes such as chemical precipita-
tion and filtration. Chemicals used in advanced
wastewater treatment processes, such as aluminum,
iron, salts, lime, or organic polymers, increase sludge
mass and usually sludge volume. Generally, if lime or
polymers are used, the thickening and dewatering char-
acteristics of sludge will improve, whereas if iron or
aluminum salts are used, the dewatering and thickening
capacity of the sludge will usually be reduced.
4.12.4 Domestic Septage
Domestic septage is considered sewage sludge by the
Part 503 regulation and is defined and discussed in
Table 4-7. Chemical and Physical Characteristics of
Domestic Septage (U.S. EPA, 1993b)
Parameter
Concentration, mg/kg
(dry weight basis)
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
Nitrogen as N
Phosphorus as P
PH
Grease
Biochemical oxygen demand (BOD5)
Total solids (as normally spread)
4
3
14
140
35
0.15
-
15
2
290
2%
<1%
6-7
6-12%
6,480 mg/L
3.4%
Chapter 11. Table 4-7 shows some of the characteristics
of domestic septage. Domestic septage may foam and
generally has a strong odor (U.S. EPA, 1978). Settling
properties are highly variable. Some domestic septage
settles readily to about 20 to 50 percent of its original
volume, while others show little settling (U.S. EPA, 1979).
4.13 Effects of Wastewater and Sludge
Treatment Processes on Sewage
Sludge Characteristics
The effects of wastewater and sludge treatment proc-
esses on sewage sludge characteristics have been
discussed above as they pertain to specific sludge
parameters. This section focuses on the broader ef-
fects of treatment on sewage sludge characteristics,
highlighting the variable nature of treated sludge and
thus the need for site-specific sludge characterization.
Table 4-1 lists the various types of treatment proc-
esses, a number of which can be used to meet the
Part 503 pathogen or vector attraction reduction re-
quirements (see Chapters). Table 4-8 shows nutrient
levels found in sewage sludge subjected to different
treatment processes. EPA's Process Design Manual
for Sludge Treatment and Disposal (U.S. EPA, 1979)
provides further information on sludge treatment
technologies.
Sewage sludge is virtually always treated by a stabiliza-
tion process prior to land application. Stabilization re-
duces the volume of raw sludge by 25 to 40 percent
because much of the volatile solids are degraded to
35
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Table 4-8. Nutrient Levels in Sewage Sludge From Different Treatment Processes (Sommers, 1977)a
Nutrient
Organic C (%)
Total N (%)
NHJ-N (mg/kg)
NOg-N (mg/kg)
Total P (%)
K(%)
Na (%)
Ca (%)
Sludge
Treatment
Process13
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
Anaerobic
Aerobic
Other
All
No. of
Samples
31
10
60
101
85
38
68
191
67
33
3
103
35
8
3
45
86
38
65
189
86
37
69
192
73
36
67
176
87
37
69
193
Range
18-39
27-37
6.5-48
6.5-48
0.5-17.6
0.5-7.6
<0. 1-10.0
<0. 1-17.6
120-67,600
30-11,300
5-12,500
5-67,600
2-4,900
7-830
—
2-4,900
0.5-14.3
1.1-5.5
<0. 1-3.3
<0. 1-14.3
0.02-2.64
0.08-1.10
0.02-0.87
0.02-2.64
0.01-2.19
0.03-3.07
0.01-0.96
0.01-3.07
1 .9-20.0
0.6-13.5
0.12-25.0
0.1-25.0
Median
26.8
29.5
32.5
30.4
4.2
4.8
1.8
3.3
1,600
400
80
920
79
180
—
149
3.0
2.7
1.0
2.3
0.30
0.39
0.17
0.30
0.73
0.77
0.11
0.24
4.9
3.0
3.4
3.9
Mean
27.6
31.7
32.6
31.0
5.0
4.9
1.9
3.9
9,400
950
4,200
6,540
520
300
780
490
3.3
2.9
1.3
2.5
0.52
0.46
0.20
0.40
0.70
1.11
0.13
0.57
5.8
3.3
4.6
4.9
1 Concentrations and percent composition are on a dried solids basis.
' "Other" includes lagooned, primary, tertiary, and unspecified sludges. "AH" signifies data for all types of sludges.
carbon dioxide, methane, or other end products. This
decomposition of the organic matter in the sludge and
the subsequent release of carbon dioxide, ammo-
nium, hydrogen sulfide, and phosphate result in lower
levels of organic carbon (C), nitrogen (N), sulfur (S),
and phosphorous in the stabilized sludge than was
present in the raw sludge entering the stabilization
unit. Stabilization processes include aerobic and an-
aerobic digestion and composting, among others. The
actual amounts of stabilized sludge produced in a
treatment works depends on operational parameters
(e.g, temperature, mixing, detention time) of the sta-
bilization process used.
Composting of sewage sludge results in further de-
creases in the organic constituents. If the sludge is
mixed with a bulking agent (e.g., wood chips) during com-
posting to facilitate aeration and rapid stabilization, some
of the bulking agent will remain in the compost (even
if screened), resulting in dilution of sludge components
(e.g., nutrients, metals). The extensive biological activity
that occurs during composting results in further de-
creases in the organic N, C, and S content of the sludge.
In general, the organic N content of sludge decreases
in the following order: raw, primary or waste activated,
digested, and composted.
Wastewater and sewage sludge treatment processes
often involve the addition of ferric chloride, alum, lime,
or polymers. The concentration of these added ele-
ments increase their concentration in the resultant
sludge. In addition, the added compound can have
other indirect effects on sludge composition. For exam-
ple, alum precipitates as aluminum hydroxides, which
can subsequently adsorb phosphorus and coprecipitate
with trace metals such as cadmium. Lime (calcium
oxide or hydroxide) used as a sludge stabilization agent
will ultimately precipitate in sludge as calcium carbon-
ate, which also can retain phosphorus and metals. Lime
addition also may result in losses of ammonia through
volatilization.
36
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4.14 Effects of Pretreatment and
Pollution Prevention Programs on
Sewage Sludge Characteristics
EPA first established pretreatment requirements (40
CFR Part 403) in 1978. Pretreatment programs require
industries to limit the concentrations of certain pollutants
in wastewater discharged to a treatment works, includ-
ing heavy metals and organic chemicals.
In addition to pretreatment programs, pollution preven-
tion programs designed to reduce or eliminate pollution
are often developed as a joint effort by industry and
government and are undertaken voluntarily by a
company. The quality of sewage sludge has continu-
ally improved over the years, and many regulators,
researchers, and treatment works managers believe
that pretreatment and pollution prevention programs
have been significant factors in achieving this improve-
ment. For example, levels of cadmium, chromium, and
lead have decreased since the 1970s, as shown by data
from EPA's 1982 "40 City Study" (U.S. EPA, 1982) and
1990 NSSS (Shimp et al., 1994).
4.15 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
703-487-4650
Edmonds, R. 1979. Microbiological characteristics of dewatered
sludge following application to forest soils and clearcut areas. In:
Sopper, W, and S. Kerr, eds. Application of municipal sewage
effluent and biosolids on forest and disturbed land. University
Park, PA: Pennsylvania State University Press.
Furr, A., A. Lawrence, S. long, M. Grandolfo, R. Hofstader, C. Bache,
W. Gutenmann, and D. Lisk. 1976. Multi-element and chlorinated
hydrocarbon analysis of municipal sewages of American cities.
Environ. Sci. Technol. 10:683-687.
Jakubowski, W. 1988. Ascaris ova survival in land application condi-
tions. EPA Administrator's Item Deliverable No. 2799 (May 1988).
Kowal, N. 1983. An overview of public health effects. In: Page, A., T.
Gleason, III, J. Smith, Jr., I. Iskandar, and L. Sommers, eds. Proceed-
ings of the 1983 Workshop on Utilization of Municipal Wastewater and
Sludge on Land. Riverside, CA: University of California, pp. 329-394.
Ryan, J., D. Keeney, and L. Walsh. 1973. Nitrogen transformations
and availability of an anaerobically digested sewage sludge in soil.
J. Environ. Quality 2:489-492.
Sagik, B., B. Moore, and C. Forber. 1979. Public health aspects related
to the land application of municipal sewage effluents and sludges.
In: Sopper, WE., and S.M. Kerr, eds. Utilization of municipal sewage
effluent and sludge on forest and disturbed land. University Park,
PA: Pennsylvania State University Press, pp. 241-263.
Shimp, G., K. Hunt, S. McMillian, and G. Hunter. 1994. Pretreatment
raises biosolids quality. Environ. Protection 5(6).
Sommers, L. 1977. Chemical composition of sewage sludges and
analysis of their potential use as fertilizers. J. Environ. Quality
6:225-239.
Sommers, L., D. Nelson, J. Yahner, and J. Mannering. 1972. Chemi-
cal composition of sewage sludge from selected Indiana cities.
Oroc. Indiana Acad. Sci. 82:424-432.
U.S. EPA. 1994. A plain English guide to the EPA 503 biosolids rule.
EPA/832/R-93/003 (June). Washington, DC.
U.S. EPA Regions VIII and X. 1993a. Biosolids management handbook
for small to medium size POTWs. Denver, CO, and Seattle, WA.
U.S. EPA. 1993b. Domestic septage regulatory guidance. EPA/832/B-
92/005. Washington, DC.
U.S. EPA. 1992a. Control of pathogens and vector attraction in sew-
age sludge. EPA/625/R-92/013. Cincinnati, OH.
U.S. EPA. 1992b. Technical support document for land application of
sewage sludge, Vol. I. EPA/822/R-93900/9 (NTIS PB93110583).
Washington, DC.
U.S. EPA. 1992c. Technical support document for reduction of patho-
gens and vector attraction in sewage sludge. NTIS PB93110609.
Washington, DC.
U.S. EPA. 1990. National Sewage Sludge Survey: Availability of in-
formation and data, and anticipated impacts on proposed regula-
tions. Fed. Reg. 55(218).
U.S. EPA. 1987. Survival and transport of pathogens in sludge-
amended soil: A critical literature review. EPA/600/2-87/028. Cin-
cinnati, OH.
U.S. EPA. 1984. Use and disposal of municipal wastewater sludge.
EPA/625/10-84/003. Cincinnati, OH.
U.S. EPA. 1982. Fate of priority pollutants in publicly owned treatment
works. EPA/440/1-82/303. Washington, DC.
U.S. EPA. 1979. Process design manual for sludge treatment and
disposal. EPA/625/1-79/011. Cincinnati, OH.
U.S. EPA. 1978. Treatment and disposal of septic tank sludges: A
status report. Distributed at the Seminar on Small Wastewater
Facilities. Cincinnati, OH.
37
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Chapter 5
Site Evaluation and Selection Process
5.1 General
The process of planning a sewage sludge land applica-
tion project begins with the collection and assessment
of basic data on sludge characteristics. The sludge char-
acteristics in conjunction with estimated application
rates can then be compared to applicable federal, state,
and local regulations for an initial assessment of sewage
sludge suitability for any of the land application practices
discussed in Chapter 2. The public's perception and
acceptance of such a proposed project, as well as land
availability, transportation modes, and climatic condi-
tions, must all be considered and evaluated to determine
the feasibility of the proposed program.
The careful identification, evaluation, and ultimate selec-
tion of land application sites can prevent future environ-
mental problems, reduce monitoring requirements,
minimize overall program costs, and moderate or elimi-
nate adverse public reaction. Poor site selection and
management practices in the past have resulted in en-
vironmental problems and public resistance.
Section 5.2 gives an overview of key requirements in the
Part 503 regulation that affect site selection for land
application of sewage sludge. Figure 5-1 provides an
overview of a six-step process for identifying the best
sewage sludge land application practice and the best
site(s) for land application of sewage sludge. Sections
5.4 though 5.8 describe each of the six steps in more
detail, and Section 5.9 provides an example of the site
selection procedures that can be used for a typical
medium-sized community.
5.2 Part 503 Requirements
The Part 503 rule contains several provisions that must
be considered during site selection for land application
of sewage sludge. These provisions are discussed
briefly below and are explained further in Chapter 3.
Some state and local governments have developed ad-
ditional or more stringent regulations; therefore, it is
important to check with state and local regulatory and
permitting agencies where the proposed project is lo-
cated to determine what requirements apply.
5.2.1 Protection of Surface Water and
Wetlands
Part 503 specifies that sewage sludge cannot be applied
to flooded, frozen, or snow-covered agricultural land,
forests, public contact sites, or reclamation sites in such
a way that it enters a wetland or other waters of the
United States, except as provided in a Section 402
(NPDES) or Section 404 (dredge and fill) permit. In
addition, sewage sludge cannot be applied to agricul-
tural land, forests, or reclamation sites that are 10 me-
ters or less from waters of the United States, unless
otherwise specified by the permitting authority.
Other federal regulations also may apply to sewage
sludge application in wetlands. These include:
• Sections 401, 402, and 404 of the Clean Water Act
• The Rivers and Harbors Act of 1989
• Executive Order 11990, Protection of Wetlands
• The National Environmental Policy Act
• The Migratory Bird Conservation Act
• The Fish and Wildlife Coordination Act
• The Coastal Zone Management Act
• The Wild and Scenic Rivers Act
• The National Historic Preservation Act
Additional published information that may be useful in-
cludes USGS topographic maps, National Wetland In-
ventory maps, Soil Conservation Service (SCS) soil
maps, and wetland inventory maps prepared locally.
Some of the local U.S. Army Corps of Engineers District
Offices can provide a wetland delineation to indicate
whether all or some portion of a potential or actual land
application site is in a wetland. The state agency regu-
lating activities in wetlands should also be asked to
inspect the area in question. The definition of a wetland
and the regulatory requirements for activities in wet-
lands may be different at the state level.
39
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Determine Sewage Sludge Characteristics (Chemical,
Biological, and Physical, Chapter 4)
Preliminary Planning (Section 5.4)
Review Applicable Federal, State, and Local
Regulations and Guidelines for Land Application of
Sewage Sludge (Section 5.4.1)
Public Participation (Section 5.4.2)
Estimate Land Area Required for Sewage Sludge
Application, and Availability of Land Area Neccessary
(Section 5.4.3)
Assess Sewage Sludge Transport Modes and Their
Feasibility (Section 5.4.4)
Phase I Site Evaluation and Site Screening (Section 5.5) I
Existing Information Sources (Section 5.5.1)
Land Use (Section 5.5.2)
Site Physical Characteristics (Section 5.5.3)
Site Screening (Section 5.5.4)
Phase II Site Evaluation (Section 5.6 and Chapter 6)
Selection of Land Application Practice (Section 5.7)
Final Site Selection (Section 5.8)
Figure 5-1. Simplified planning steps for a sewage sludge land application system.
5.2.2 Protection of Threatened and
Endangered Species
Under Part 503, sewage sludge may not be applied to
land if it is likely to adversely affect a threatened or
endangered species listed under Section 4 of the En-
dangered Species Act or the designated critical habitat
of such a species. The Threatened and Endangered
Species List can be obtained from the U.S. Fish and
Wildlife Service's (FWS's) Publications Office in Wash-
ington, DC. Critical habitat is defined as any place where
a threatened or endangered species lives and grows
during any stage of its life cycle.
Any direct or indirect action (or the result of any direct
or indirect action) in a critical habitat that diminishes the
likelihood of survival and recovery of a listed species is
considered destruction or adverse modification of a criti-
cal habitat. Individuals may contact the Endangered Spe-
cies Protection Program in Washington, DC. or Fish and
Wildlife Service Field Offices for more information about
threatened and endangered species considerations in
their area. State departments governing fish and game
also should be contacted for specific state requirements.
5.2.3 Site Restrictions
Restrictions for the harvesting of crops and turf, grazing
of animals, and public access (see Chapters) also must
be met when sewage sludge that meets the Part 503
Class B pathogen requirements is land applied.
40
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5.3 Planning and Selection Process
As shown in Figure 5-1, this manual suggests a phased,
six-step planning and site selection approach.
5.4 Preliminary Planning
Careful preliminary planning will help minimize delays
and expenses later on in the process by identifying legal
constraints (Section 5.4.1) and obtaining public input
early in the process (Section 5.4.2). A preliminary esti-
mate of land area requirements for different land appli-
cation practices (Section 5.4.3) and a preliminary
identification of feasible sewage sludge transportation
options (Section 5.4.4) helps focus the Phase I site
evaluation and site screening process (Section 5.5). The
transportation assessment is especially important for
defining the geographic search area for potential land
application sites.
5.4.1 Institutional and Regulatory Framework
All current federal, state, county, and municipal regu-
lations and guidelines should be reviewed during the
preliminary planning process. Depending on local pro-
cedure, permits may be required from both state and
local regulatory agencies. Figure 5-2 shows the agen-
cies that have jurisdiction over land application of sew-
age sludge. Federal requirements under the Part 503
rule are described in detail in Chapter 3 of this manual.
5.4.2 Public Participation
Public participation is critical during the early stages of
planning a land application project. Most involvement
should come at the beginning of the planning process
when public input has the greatest potential to shape the
final plan. This early involvement helps determine the
limits to public and political acceptability of the project.
During this phase, the public plays a constructive, as
opposed to a reactive, role in decision-making.
Site selection generally involves a preliminary screening
of numerous potential sites after which several sites are
selected for more detailed investigation. These selected
sites should be subjected to intense public scrutiny. It is
at this point that public participation can play a particu-
larly formative role in determining the final site and
design and operation procedures.
Most public interest and involvement—including the
most vocal and organized protests—occur during the
site selection stage. Therefore, the major thrust of the
public participation program should come during this
stage, with a particular emphasis on two-way communi-
cation using such avenues as public meetings, work-
shops, and radio talk shows.
Chapter 12 provides a detailed discussion of how to
design and implement a public participation program for
a land application project.
5.4.3 Preliminary Land A rea Requirements
A precise estimate of the land area required for sewage
sludge application should be based on design calcula-
tions provided in Chapters 7, 8, and 9 for the land
application practice under consideration. However, for
preliminary planning, a rough estimate of the land appli-
cation area which might be necessary can be obtained
from Table 5-1. (Note that different practices may not
necessarily involve repeated annual applications.)
As an example, assume that the project is intended to
land apply 1,000 t (1,100 T), dry weight, of sewage
sludge annually. Using the typical rates shown in Ta-
ble 5-1, a very rough estimate of the area required
for agricultural land application would be 90 ha (220
ac), plus additional area required, if any, for buff-
er zones, sludge storage, etc. For a one-time appli-
cation of 1,0001 of sewage sludge at a land reclamation
site, the typical values shown in Table 5-1 indicate that
9 ha (22 ac) would be required.
5.4.4 Sewage Sludge Transport A ssessment
Transport can be a major cost of a land application
project, and requires a thorough analysis. This section
is intended only to provide a brief summary of the alter-
natives that may be considered during the preliminary
planning phase.
Sewage sludge can be transported by truck, pipeline, or
rail. In certain instances, combined transport methods
(e.g., pipeline-truck) are also used. The choice of a
transportation method depends on the type of land se-
lected, the volume and solids content of the sewage sludge,
and the distance to and number of destination points.
The first consideration is the nature of the sewage
sludge itself. As shown in Table 5-2, sewage sludge is
classified for handling/transport purposes as either liq-
uid, sludge cake, or dried, depending on its solids
content. Only liquid sludge can be pumped and trans-
ported by pipeline. Pipeline transport can be cost
effective for long-distance pumping of liquid sludge
(usually less than 8 percent solids) but has been used
for sludge up to 20 percent solids over very short dis-
tances. If liquid sludge is transported by truck or rail,
closed vessels must be used, e.g., tank truck, rail-
road tank cars, etc. Sludge cake can be transported
in watertight boxes, and dry sludge can be trans-
ported in open boxes (e.g., dump trucks).
Trucks and pipelines are the most common form of
transport. Rail transport also is used in the United
States. An example is rail shipment of sludge from New
York to Texas.
41
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Agencies With Jurisdiction Over Land Application
State
U.S. Environmental
Protection Agency
Office of Surface
Mining Reclamation
and Enforcement
(reclamation sites)
Federal f u.S. Fish and
Wildlife Service
(protection of
threatened and
endangered species)
XU.S. Army Corps of
Engineers (dredge-
and-fill permits)
National
'Regional
Office of Science and Technology
(Part 503 regulation)
.Office of Wastewater Management
(permitting, state sludge programs,
beneficial use)
ffice of Enforcement and Compliance
^Office of Solid Waste (sewage sludge
generated at industrial facilities)
onstruction Grants
Review
olid Waste Program
Review
Permitting and
Enforcement (Part 503
permits)
Wastewater Programs
Environmental Quality (surface water,
ground water, soils, etc).
Solid Waste Management
Public Health
Agriculture
Transportation
Land Use
• Conservation/ Environmental Quality
• Public Health
• Solid Waste Management
Figure 5-2. Institutional framework (adapted from Deese et al., 1980).
Local
(Receiving
Community)
Truck transport allows greater flexibility than any other
transport method. Destinations can be changed with
little advance notice, and the sludge can be distributed
to many different destinations. If trucks must be routed
along residential or secondary streets, public concern
about congestion and the risk of sludge spills must be
considered. Most land application systems use truck
transport, either alone or after sludge transport by pipe-
line or rail to an intermediate storage facility. Liquid
sludge of up to 10 percent solids concentration (depend-
ing on its viscosity) can be transported in tank trucks.
Dewatered sludge with a greater than 10 percent solids
concentration can usually be transported in open trucks
with watertight seals if precautions are taken to prevent
spillage. Dried and composted sludge with approxi-
mately 50 percent or greater solids concentration can be
transported without watertight seals or splash guards
(U.S. EPA, 1984).
The desirable limit for a truck haul distance is about 25
to 40 km (15 to 25 mi) one way. For low cost land
application of liquid sludge, the land must generally be
within about a 16-km (10-mi) radius of the treatment
plant. Mechanically dewatered sludge can generally be
economically transported to a site up to about 22 km (20 mi).
Air-dried sludges, which have solids concentrations in ex-
cess of 55 to 60 percent, can be economically transported
a greater distance. In evaluating transportation costs,
42
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Table 5-1. Preliminary Estimates of Sewage Sludge Applications (Dry Weight) for Different Types of Land
Reported Range of
Application Rates
Typical Rate
t/ha
T/ac
t/ha
T/aca
Land Type
Time Period of Application
Agricultural Land
Forest Land
Land Reclamation Site
Annual or twice annually
Annually, or at 3-5 year intervals
One time
2-70
1 0-220
7-450
1-30
4-100
3-200
10
18
112
5
8
50
at = metric tonnes
T = English tons (short)
Table 5-2. Sewage Sludge Solids Content and Handling
Characteristics
Sludge Type Solids Content (%) Transport Methods
Liquid
Sludge cake ("wet"
solids)
Dried
1 to 10 Gravity flow, pump,
pipeline, tank transport
10 to 30 Conveyor, auger, truck
transport (watertight
box)
50 to 95 Conveyor, bucket,
truck transport (box)
the cost of dewatering must be weighed against the cost
savings that can result from transporting a drier sludge
(U.S. EPA, 1984).
Tables 5-3 and 5-4 present some practical considera-
tions for hauling sludge. Table 5-5 provides a rating of
transport modes in terms of reliability, staffing needs,
energy requirements, and costs. For a detailed discus-
sion of sludge transport, see Chapter 14.
5.5 Phase I Site Evaluation and Site
Screening
A Phase I site evaluation uses the information obtained
during preliminary planning, namely the estimate of pre-
liminary land area requirements (Section 5.4.3) and the
results of the transportation assessment (Section 5.4.4),
to identify potential land application sites. Existing infor-
mation sources (Section 5.5.1) are used to identify mul-
tiple sites considering land use (Section 5.5.2) and
physical characteristics (Section 5.5.3) within the area
that sewage sludge can feasibly be transported. Site
screening allows elimination of unsuitable areas due to
physical, environmental, social, or political reasons
(Section 5.5.4), and identification of sites for more detailed
Phase II site evaluation (Section 5.6 and Chapters).
5.5.1 Existing information Sources
Sources of information on land characteristics, cropping
patterns, and other relevant data in the geographic
search area include:
• U.S. Department of Agriculture - Consolidated Farm
Service Agency, Natural Resources Conservation
Table 5-3. Transport Modes for Sewage Sludge
Sewage Sludge Type Transportation Considerations
Liquid Sludge
Vehicles:
Tank Truck
Farm Tank Wagon and Tractor
Pipeline
Rail Tank Car
Semisolid or Dried Sludge
Truck
Farm Manure Spreader
Rail Hopper Car
Capacity - up to maximum load allowed on road, usually 6,600 gal maximum. Can have gravity
or pressurized discharge. Field trafficability can be improved by using flotation tires at the cost of
rapid tire wear on highways.
Capacity - 800 to 3,000 gal. Principal use would be for field application.
Need minimum velocity of 1 fps to keep solids in suspension; friction decreases as pipe diameter
increases (to the fifth power); buried pipeline suitable for year-round use. High capital costs.
100-wet-ton (24,000-gal) capacity; suspended solids will settle while in transit.
Commercial equipment available to unload and spread on ground; need to level sludge piles if
dump truck is used. Spreading can be done by farm manure spreader and tractor.
Appropriate for small systems where nearby farmlands are accessible by a manure spreader.
May need special unloading site and equipment for field application, although in many cases can
use conventional unloading equipment.
43
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Table 5-4. Auxiliary Facilities for Sewage Sludge Transport
(Gulp et al., 1980)
Transport Mode
Liquid
Loading storage
Loading equipment
Dispatch office
Dock and/or control
building
Railroad siding(s)
Unloading equipment
Unloading storage*
Dewatered
Loading storage
Loading equipment
Dispatch office
Dock and/or control
building
Railroad siding(s)
Unloading equipment
Unloading storage
* Storage required for
normal plant sludge
^ Not applicable.
Truck
No*
Yes
Yes
NA
NA
Yes
No
Yes*
Yes
Yes
NA
NA
Yes
No
one or two
storage.
Railroad
Yes
Yes
Yes
NA
Yes
Yes
Yes
Yes
Yes
Yes
NA
Yes
Yes
No
truckloads is
Barge
Yes
Yes
Yes
Yes
NA
Yes
Yes
NA
NA
NA
NA
NA
NA
NA
Pipeline
Yes
Yes
NA1"
Yes
NA
NA
Yes
NA
NA
NA
NA
NA
NA
NA
small compared with
Table 5-5. Evaluation of Sewage Sludge Transport Modes
(Gulp et al., 1980)
Transport Mode Alternatives
Characteristics Truck Pipeline Railroad
Reliability and 131
Complexity1
Staffing Skills2 1 3 2
Staff Attention (Time)3 3 2 1
Applicability and 1 3 2
Flexibility4
Energy Used5 862
Costs
Capital Investment Low High —
Operation, Fairly High Low —
Maintenance, and Labor
Overall6 — — Generally
High7
1 1 = most reliable, least complex; 2 = intermediate; 3 = least
reliable, most complex.
2 1 = least skills; 2 = intermediate; 3 = highest skills.
3 Attention time increases with magnitude of number.
4 1 = wide applicability (all types of sludge); 3 = limited applicability,
relatively flexible.
5 1 = lowest; 8 = highest.
6 Overall costs are a function of sludge quantities and properties
(percent solids), distance transported, and need for special
storage loading and unloading equipment.
7 Rail costs would generally be in the form of freight charges; costs
could be lower for large volumes of sludge, or if long-distance rail
is less expensive than truck transport.
Storage assumed to be a part of another unit process.
** Elevated storage for ease of gravity transfer to trucks.
Service, Forest Service, and Cooperative State Re-
search Education and Extension Service.
• U.S. Geological Survey.
• U.S. EPA.
• U.S. Army Corps of Engineers.
• Private photogrammetry and mapping companies.
• State agricultural mining and geologic agencies.
• State water resource agencies.
• State universities and local colleges.
• Local planning and health departments.
• Local water conservation districts.
• Ground water users (municipalities, water compa-
nies, individuals, etc.).
• State land grant universities and water resource centers.
Section 5.5.3.5 identifies major sources for climatic data.
5.5.2 Land Use and A vail ability
Prevailing or projected land use often exerts a signifi-
cant influence on site selection, as well as on accep-
tance of a particular sewage sludge land application
practice. It is necessary to determine both current and
future land use in assessing the land area potentially
suitable and/or available for sewage sludge application.
Important considerations include zoning compliance,
aesthetics, and site acquisition.
5.5.2.1 Current Land Use
Current land use patterns will help identify areas where
land application of sewage sludge may be acceptable.
The local SCS and Agricultural Extension Service repre-
sentatives have knowledge of local farming, forestry, min-
ing, and other land use practices. The SCS will, in many
cases, have a comprehensive county soil survey with
aerial photo maps showing the land area.
• Agricultural Lands. To a great extent, prevailing
farming practices dictate the acceptability of agricul-
tural land application. Small land holdings in a non-
agricultural community may limit application to this
type of land. An area devoted almost exclusively to
production of human food crops restricts the periods
when sewage sludge can be applied to land. Areas
44
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with a mixture of row crops, small grains, hay crops, and
pastures may allow sewage sludge application through-
out much of the year, depending on farming cycles.
• Forest Lands. A consideration in sewage sludge ap-
plication to forest lands is the potential need to control
public access for a period of time after sludge appli-
cation. Therefore, the most desirable sites are often
those owned by or leased to commercial growers,
which already control public access. Publicly owned
forest land has been used for sewage sludge appli-
cation, but may require interagency negotiations and
greater public education efforts than the use of pri-
vately owned land.
• Reclamation Sites. Potential reclamation sites are
relatively easy to identify in a particular local area.
Sewage sludge land application design is influenced
by the potential future use of the reclaimed land (i.e.,
agriculture, silviculture, parks, greenbelts, etc.). The
application of sewage sludge is often a one-time op-
eration at reclamation sites rather than a repetitive
series of applications on the same site. It is therefore
necessary that (1) the mining or other operations will
continue to generate disturbed land to which sludge
can be applied, or (2) the reclamation area is of
sufficient size to allow a continuing sludge application
program over the design life of the project. State and
federal guidelines may dictate the criteria for sludge
applications and subsequent management.
• Public Contact Sites. Public contact sites such as
parks, golf courses, and cemeteries are good candi-
dates for land application of sewage sludge. Because
municipalities often own these sites, a land applica-
tion program may be easier to arrange at these sites
than at privately owned sites. Bagged sewage sludge
is often used at public contact sites having a small
land area. Regulatory requirements and other con-
siderations for the use of sewage sludge at public
contact sites are explained in Chapter 10.
• Lawns and Home Gardens. Bagged sewage sludge
can be used like other fertilizers for lawns and home
gardens. Regulatory and other considerations for use
of sewage sludge on lawns and home gardens are
discussed in Chapter 10.
5.5.2.2 Future Land Use
Projected land use plans, where they exist, should be
included when considering sewage sludge land applica-
tion. Regional planners and planning commissions
should be consulted to determine the projected use of
potential land application sites and adjacent properties.
If the site is located in or near a densely populated area,
extensive control measures may be needed to over-
come concerns and minimize potential aesthetic prob-
lems that may detract from the value of adjacent
properties. Master plans for existing communities
should be examined. The rate of industrial and/or mu-
nicipal expansion relative to prospective sites can sig-
nificantly affect long-term suitability.
5.5.2.3 Zoning Compliance
Zoning and land use planning are closely related, and
zoning ordinances generally reflect future land use plan-
ning. Applicable zoning laws, if any, which may affect
potential land application sites should be reviewed con-
currently with land use evaluations. Since it is unusual
that a community will have a specific area zoned for
sludge/waste storage, project proponents may need to
seek a zoning change for separate sewage sludge stor-
age facilities.
5.5.2.4 Aesthetics
Selection of a land application site and/or sewage
sludge land application practice can be affected by com-
munity concern over aesthetics, such as noise, fugitive
dust, and odors. In addition to application site area
concerns, routes for sludge transport vehicles must be
carefully evaluated to avoid residential areas, bridge
load limitations, etc. Disruption of the local scenic char-
acter and/or recreational activities, should they occur,
may generate strong local opposition to a sewage
sludge management program. Every attempt must be
made to keep the application site compatible with its
surroundings and, where possible, enhance the beauty
of the landscape. Buffer zones are usually required to
separate sewage sludge application sites from resi-
dences, water supplies, surface waters, roads, parks,
playgrounds, etc.
5.5.2.5 Access
The preliminary sewage sludge transportation feasibility
assessment (Section 5.4.4) will narrow the geographic
search area for potential sites by focusing attention on
areas that are adjacent to or in the vicinity of existing
transportation corridors (e.g., roads, rail lines) for the
selected sewage sludge transportation modes. Areas
that are too distant for economic transport, or to which
access is restricted for other reasons (such as physical
barriers), can be eliminated from further consideration.
5.5.2.6 Site Acquisition
Application of sewage sludge to agricultural land can
often be accomplished without direct purchase or lease
of the land. Well-prepared educational and public par-
ticipation programs early in the planning stages often
identify numerous farmers willing to participate in a land
application program. This type of arrangement may be
more acceptable to the public in some cases than pur-
chasing land for sewage sludge land application.
45
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Several different contractual arrangements between
municipalities and landowners for agricultural land ap-
plication have been successfully employed, including:
• The municipality transports and spreads the sludge
at no expense to the landowner.
• The municipality transports and spreads the sludge
and pays the landowner for the use of his land.
• The landowner pays a nominal fee for the sewage
sludge and for the municipality to transport and
spread the sludge. This is most common for agricul-
tural sites where local demand for sewage sludge as
a fertilizer or soil conditioner exists.
• The municipality hauls the sludge and the landowner
spreads it.
• The landowner hauls and spreads the sludge.
A written contract between the landowner and the sew-
age sludge preparer and/or applier is highly recom-
mended. In some instances, the preparer/applierwill be
the municipality; in other cases, it will be a private
preparer/applier who is transporting and spreading for
the municipality. The Part 503 rule contains require-
ments for both preparers and appliers (see Chapter 3).
The principal advantage of a written contract is to ensure
that both parties understand the agreement prior to
applying the sewage sludge. Often, oral contracts are
entered with the best of intentions, but the landowner
and preparer/applier have differing notions of the rights
and obligations of each party. In some cases, the con-
tract may serve as evidence in disputes concerning the
performance of either the preparer/applier or the land-
owner. Suggested provisions of contracts between the
applier and landowner are shown in Table 5-6.
The use of land without purchase or lease may also be
applicable for land application of sewage sludge to for-
ested lands and reclamation sites. Direct purchase or
lease, however, may be necessary for large-scale sew-
age sludge management systems regardless of the type
of land at which sewage sludge is applied. In these
instances, site acquisition represents a major cost in the
implementation of the land application program.
5.5.3 Physical Characteristics of Potential Sites
The physical characteristics of concern are:
• Topography
• Soil permeability, infiltration, and drainage patterns
• Depth to ground water
• Proximity to surface water
The planner/designer should review federal and state
regulations or guidelines that place limits on these
physical characteristics of application sites. Chapter 6
addresses site physical characteristics in more detail.
This section focuses on information that can usually be
obtained from existing topographic and soil maps for the
purpose of identifying sites where more detailed inves-
tigations may be justified.
5.5.3.1 Topography
Topography influences surface and subsurface water
movement, which affects the amount of potential soil
erosion and surface water runoff containing applied
sewage sludge. These considerations have been fac-
tored into the pollutant limits established in the Part 503
regulation. Topography also can indicate the kinds of soil
to be found on a site.
Quadrangle maps published by the U.S. Geological Sur-
vey may be useful during preliminary planning and
screening to estimate slope, local depressions or wet
areas, rock outcrops, regional drainage patterns, and
water table elevations. These maps, however, usually
are drawn to a scale that cannot be relied on for evalu-
ating small parcels and do not eliminate the need for
field investigation of potential sewage sludge land appli-
cation sites. The use of regional and soil survey maps
can help eliminate potentially unsuitable areas. Table
5-7 summarizes important criteria; see Section 5.2.1 for
related Part 503 regulatory requirements.
Soils on ridge tops and steep slopes are typically well
drained, well aerated, and usually shallow. But steep
slopes, except on very permeable soils, increase the
possibility of surface runoff of sewage sludge. Soils on
concave land and broad flat lands frequently are poorly
drained and may be waterlogged during part of the year.
Soils between these two extremes will usually have
intermediate properties with respect to drainage and
runoff. Application to steep slopes (from 30 to over 50
percent) in forested areas may be possible under spe-
cific conditions (e.g., properly buffered slopes with good
forest floor/understory vegetation, depending on the
type of soil, vegetation, and sewage sludge) if it can be
shown that the risk from runoff is low. Forest sites, which
generally have a very permeable forest floor, and new
technology for applying dewatered sewage sludge in
forests greatly reduce the potential for overland flow.1
The steepness, length, and shape of slopes influence
the rate of runoff from a site. Rapid surface water runoff
accompanied by soil erosion can erode sewage sludge
soil mixtures and transport them to surface waters.
Therefore, state regulations/guidelines often stipulate
the maximum slopes allowable for sewage sludge land
application sites under various conditions regarding
sludge physical characteristics, application techniques,
and application rates. Specific guidance should be
1 Henry, C. 1995. Personal communication, Dr. Charles Henry, Pack
Forest Research Center, University of Washington, Eatonville, WA.
46
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Table 5-6. Suggested Provisions of Contracts Between
Sewage Sludge Preparer, Sludge Applier, and
Private Landowners (Sagik et al., 1979)
Identification of the landowner, the preparer, and the applier
spreading the sludge.
Location of land where application is to occur and boundaries of
the application sites.
Entrance and exit points to application sites for use by spreading
equipment.
Specification of the range of sludge quality permitted on the land.
Parameters identified might include percent of total solids;
levels of trace elements and pathogens in the sludge, and
vector attraction reduction, as regulated by Part 503; additional
state and local parameters required. The contract would specify
who is to pay for the analysis, and frequency of analysis.
Agreement on the timing of sludge application during the cropping
season. Application rates and acceptable periods of application
should be identified for growing crops, as well as periods when
the soil is wet.
Agreements on the application rate (agronomic rate). This rate
might vary through the year depending on the crop, the sludge
analyses, and when and where application is occurring.
Restrictions on usage of land for growing root crops or fresh
vegetables, or for grazing livestock.
Conditions under which either party may escape from provisions of
the contract or be subject to indemnification or liability issues.
Table 5-7. Potentially Unsuitable Areas for Sewage Sludge
Application
Areas bordered by ponds, lakes, rivers, and streams without
appropriate buffer areas.
Wetlands and marshes without a permit.
Steep areas with sharp relief.
Undesirable geology (karst, fractured bedrock) (if not covered by a
sufficiently thick soil column).
Undesirable soil conditions (rocky, shallow).
Areas of historical or archeological significance.
Other environmentally sensitive areas such as floodplains or
intermittent streams, ponds, etc., as specified in the Part 503
regulation.
obtained from appropriate regulatory agencies; for gen-
eral guidance, suggested limits are presented in Table
5-8.
5.5.3.2 Soils and Geology
Soil survey reports can be obtained from local SCS
offices and are suitable for preliminary planning. When
potential sites are identified, field inspections and inves-
tigations are necessary to confirm expected conditions
(Section 5.4.2). The SCS mapping units cannot represent
areas smaller than 0.8 to 1.2 ha (approximately 2 to 3
acres). Thus, there is a possibility that small areas of
Table 5-8. Recommended Slope Limitations for Land
Application of Sewage Sludge
Slope Comment
0-3% Ideal; no concern for runoff or erosion of liquid or
dewatered sludge.
3-6% Acceptable for surface application of liquid or
dewatered sludge; slight risk of erosion.
6-12% Injection of liquid sludge required in most cases,
except in closed drainage basin and/or areas with
extensive runoff control. Surface application of
dewatered sludge is usually acceptable.
12-15% No liquid sludge application without effective runoff
control; surface application of dewatered sludge is
acceptable, but immediate incorporation is
recommended.
Over 15% Slopes greater than 15% are only suitable for sites
with good permeability (e.g., forests), where the
steep slope length is short (e.g., mine sites with a
buffer zone downslope), and/or the steep slope is a
minor part of the total application area.
soils with significantly different characteristics may be
located within a mapping unit but not identified. SCS soil
surveys provide information on typical characteristics of
soil map units that are very useful for identifying the
most favorable soils within a potential site and for com-
paring relative suitability of different possible sites. Sec-
tion 5.9.8 (Table 5-15) illustrates how relevant information
on soil types can be compiled.
The texture of the soil and parent geologic material is
one of the most important aspects of site selection
because it influences permeability, infiltration, and drain-
age. It is important that a qualified soil scientist be
involved in the assessment of soils at potential land
application sites.
With proper design and operation, sewage sludge can
be successfully applied to virtually any soil. However,
highly permeable soil (e.g., sand), highly impermeable
soil (e.g., clay; although the addition of organic material
in sewage sludge may help reduce impermeability), or
poorly drained soils may present special design require-
ments. Therefore, sites with such conditions should gen-
erally be given a lower priority during the preliminary site
selection process. Table 5-9 summarizes typical guide-
lines for soil suitability. In some cases, the favorable
aspects (i.e., location, municipal ownership, etc.) may
outweigh the costs of mitigation measures.
Soil Permeability and Infiltration
Permeability (a property determined by soil pore space,
size, shape, and distribution) refers to the ease with
which water and air are transmitted through soil. Fine-
textured soils generally possess slow or very slow per-
meability, while the permeability of coarse-textured soils
ranges from moderately rapid to very rapid. A medium-
47
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Table 5-9. Soil Limitations for Sewage Sludge Application to Agricultural Land at Nitrogen Fertilizer Rates in Wisconsin (Keeney
et al., 1975)
Degree of Soil Limitation
Soil Features Affecting Use
Available water capacity
Slight
Moderate
Severe
Slope3
Depth to seasonal water table
Flooding and ponding
Depth to bedrock
Permeability of the most restricting layer
above a 1-m depth
Less than 6%
More than 1 .2 m
None
More than 1 .2 m
0.24 to 0.8 cm/hr
6 to 12%
0.6to 1.2 m
None
0.6 to 1.2 m
0.8 to 2.4 cm/hr
0.08 to 0.24 cm/hr
More than 12%
Less than 1 m
Occasional to frequentb
Less than 0.61 m
Less than 0.08 cm/hr
More than 2.4 cm/hr
More than 2.4 cm
1.2 to 2.4 cm
Less than 1.2 cm
3 Slope is an important factor in determining the runoff that is likely to occur. Most soils on 0 to 6% slopes will have slow to very slow runoff;
soils on 6 to 12% slopes generally have medium runoff; and soils on steeper slopes generally have rapid to very rapid runoff.
b Land application may be difficult under extreme flooding or ponding conditions.
Metric conversions: 1 ft = 0.3048 m, 1 in = 2.54 cm.
textured soil, such as a loam or silt loam, tends to have
moderate to slow permeability.
Soil Drainage
Soils classified as (1) very poorly drained, (2) poorly
drained, or (3) somewhat poorly drained by the Soil
Conservation Service may be suitable for sewage
sludge application if runoff control is provided. Soils
classified as (1) moderately well-drained, (2) well
drained, or (3) somewhat excessively drained are gen-
erally suitable for sewage sludge application. Typically,
a well-drained soil is at least moderately permeable.
5.5.3.3 Surface Hydrology, Including
Floodplains and Wetlands
The number, size, and nature of surface water bodies
on or near a potential sewage sludge land application
site are significant factors in site selection due to poten-
tial contamination from site runoff and/or flood events.
Areas subject to frequent flooding have severe limita-
tions for sewage sludge application. Engineered flood
control structures can be constructed to protect a land
application site against flooding, but such structures can
be prohibitively expensive.
5.5.3.4 Ground Water
For preliminary screening of potential sites, it is recom-
mended that the following ground-water information for
the land application area be considered:
• Depth to ground water (including historical highs and lows).
• An estimate of ground water flow patterns.
When a specific site or sites has been selected for
sewage sludge application, a detailed field investigation
may be necessary to determine the above information.
During preliminary screening, however, published general
resources may be located at local USGS or state water
resource agencies.
Generally, the greater the depth to the water table, the more
desirable a site is for sewage sludge application. Sewage
sludge should not be placed where there is potential for
direct contact with the ground-water table. The actual
thickness of unconsolidated material above a permanent
water table constitutes the effective soil depth. The desired
soil depth may vary according to sludge characteristics,
soil texture, soil pH, method of sludge application, and
sludge application rate. Table 5-10 summarizes recom-
mended criteria for the various land application practices.
The type and condition of consolidated material above the
watertable is also of major importance forsites where high
application rates of sewage sludge are desirable. Frac-
tured rock may allow leachate to move rapidly. Unfractured
bedrock at shallow depths will restrict water movement,
with the potential for ground water mounding, subsurface
lateral flow, or poor drainage. Limestone bedrock is of
particular concern where sinkholes may exist. Sinkholes,
like fractured rock, can accelerate the movement of
leachate to ground water. Thus, potential sites with potable
ground water in areas underlain by fractured bedrock, by
Table 5-10. Recommended Depth to Ground Water
Type of Site Drinking Water Aquifer3 Excluded Aquiferb
Agricultural
Forest
Reclamation
1-2 m
2mc
1-2 m
0.5 m
0.7m
0.5 m
States may have other depth-to-ground water requirements.
b Clearances are to ensure trafficability of surface, not for ground
water protection; excluded aquifers are not used as potable water
supplies.
c Seasonal (springtime) high water and/or perched water less than 1 m
are not usually a concern.
Metric conversion: 1 m = 3.28 ft.
48
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unfractured rock at shallow depths, or with limestone
sinkholes should be avoided.
5.5.3.5 Climate
Analysis of climatological data is an important consid-
eration for the preliminary planning phase. Rainfall, tem-
perature, evapotranspiration, and wind may be
important climatic factors affecting land application of
sewage sludge, selection of land application practices,
site management, and costs. Table 5-11 highlights the
potential impacts of some climatic regions on the land
application of sewage sludge.
Meteorological data are available for most major cities
from three publications of the National Oceanic and
Atmospheric Administration (NOAA):
• The Climatic Summary of the United States.
• The Monthly Summary of Climatic Data, which pro-
vides basic data, such as total precipitation, maxi-
mum and minimum temperatures, and relative
humidity, for each day of the month, and for every
weatherstation in the area. Evaporation data are also
given, where available.
• Local Climatological Data, which provides an annual
summary and comparative data for a relatively small
number of major weather stations.
This information can be obtained by written request from
NOAA, 6010 Executive Boulevard, Rockville, Maryland
20852. Another excellent source is the National Climatic
Center in Asheville, North Carolina 28801. Weather data
may also be obtained from local airports, universities,
military installations, agricultural and forestry extension
services and experiment stations, and agencies manag-
ing large reservoirs.
Table 5-11. Potential Impacts of Climatic Regions on Land
Application of Sewage Sludge (Gulp et al., 1980)
Climatic Region
Impact
Warm/Arid
Warm/Humid Cold/Humid
Operation Time
Operation Cost
Storage
Requirement
Salt Buildup
Potential
Leaching
Potential
Runoff Potential
Year-round
Lower
Less
High
Low
Low
Seasonal
Higher
More
Low
High
High
Seasonal
Higher
More
Moderate
Moderate
High
5.5.4 Site Screening
Site screening is an integral part of the Phase I site
evaluation process. Initially, development of land area,
transportation distance, topographic, soils, hydrologic
and other site screening criteria helps focus efforts on
collecting relevant information. One practical screening
technique involves the use of transparent (mylar) over-
lays with concentric rings drawn around the wastewater
treatment facility. The distance represented by the initial
ring will vary depending on facility location, sewage
sludge quantity, proximity of nearby communities, local
topography, and the land application practices being
considered. A small community might start with an area 20
km (12.5 miles) in diameter, while a large system may initially
screen a much larger study area. Shaded areas repre-
senting unsuitable locations are marked on the map or the
transparency. If the initial ring does not have suitable sites,
then the next ring with a larger diameter should be consid-
ered. It should be remembered that areas that are unsuitable
in their existing state can often be modified to make them
acceptable for sewage sludge application. The necessary
modifications (e.g., extensive grading, drainage structures,
flood control, etc.) may be cost-effective if the site is other-
wise attractive in terms of location, low land cost, etc.
5.5.4.1 Contact with Owners of Prospective Sites
When potential sites are identified, ownership should be
determined. Often the City Hall, County Courthouse, or
a real estate broker will have community or areawide
maps indicating the tracts of land, present owners, and
property boundaries. The County Recorder and title in-
surance companies are also useful sources of informa-
tion on property ownership, size of tracts, and related
information. Contacting landowners prematurely without
adequate preparation may result in an initial negative
reaction which is difficult to reverse. A public information
program should be prepared (see Chapter 12), and local
political support secured. The individuals involved in
making the initial owner contacts should be knowledge-
able about potential program benefits and constraints.
Initial contacts concerning the proposed project should
be made with the prospective landowners/site managers
through personal interviews. Initial contacts via telephone
are not recommended to avoid misunderstandings re-
garding the benefits of a land application program.
Ideally, the Phase I site evaluation and screening proc-
ess will identify two or three sites that merit a more
detailed Phase II site evaluation, discussed below.
5.6 Phase II Site Evaluation: Field
Investigation
The Phase II site evaluation step involves field investi-
gations of one or more sites to determine whether soil
survey and other map information used in the Phase I
49
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site evaluation and screening process is accurate and
to obtain additional, more detailed information required for
final selection of the land application practice (Section 5.7)
and final site selection (Section 5.8). Chapter 6 covers
the following aspects of Phase II investigations:
• Preliminary field site surveys.
• Procedures for detailed site investigations.
• Special considerations for detailed site evaluations
for different land application practices: agricultural,
forest land, reclamation sites, and public contact sites.
5.7 Selection of Land Application
Practice
When the most feasible land application practices have
been identified (e.g., application to agricultural land,
forests, reclamation sites, public contact sites, or lawns
and home gardens), preliminary estimates of site life
and costs (capital and O&M) for the individual practices
should be made (see Section 5.8.1). Potential social and
environmental impacts resulting from each practice also
should be assessed. Comparing these data should re-
veal the most suitable land application practice that fits
both the needs of the wastewater treatment facility and
local conditions. The facility might also consider adopt-
ing more than one land application practice (e.g., agri-
cultural and forest land application) if the combined
practices appear to be cost-effective. The flow chart
shown in Figure 5-3 summarizes the procedure for se-
lecting a land application practice.
A checklist of relevant design features for each land
application site is usually helpful for compiling informa-
tion and provides baseline data for cost estimates (Table
5-12). Individual practices can be compared and evalu-
ated based on both quantitative and qualitative factors:
• Estimated costs
• Reliability
• Flexibility
• Land area requirements and availability
• Land use effects
• Public acceptance
• Regulatory requirements (federal, state, and local)
A qualitative comparison of each land application practice
is based on the experience and judgment of the project
planners and designers. This is more difficult than a cost
comparison, because the level of each impact is more
ambiguous and subject to differences of opinion.
5.8 Final Site Selection
The final selection of the site(s) is often a simple decision
based on the availability of the bestsite(s). This is frequently
the case for small communities. If, however, the site
selection process is complex, involving many potential
sites and/or several sewage sludge use and/or disposal
practices, a weighted scoring system may be useful.
The use of a quantitative scoring system for site selection
is demonstrated in the Process Design Manual for Surface
Disposal of Sewage Sludge and Domestic Septage (U.S.
EPA, in preparation). While the criteria for selecting site(s)
for the land application practices discussed in this manual
differ somewhat from those provided in the surface dis-
posal design manual, the weighting and scoring system
may be useful. Table 5-13 presents another example of a
ranking system for forest sites, based on consideration of
topography, soils and geology, vegetation, water re-
sources, climate, transportation, and forest access.
Several other considerations should be integrated into
the decision-making process, including:
• Compatibility of sewage sludge quantity and quality
with the specific land application practice selected.
• Public acceptance of both the practice(s) and site(s)
selected.
• Anticipated design life, based on assumed applica-
tion rate, land availability (capacity), projected heavy
metal loading rates (if Part 503 cumulative pollutant
loading rates are being met, as defined in Chapter
3), and soil properties.
5.8.1 Preliminary Cost Analysis
A preliminary estimate of relative costs should be made
as part of the site selection process. These estimates
are necessary for comparing alternative sites and/or
land application practices.
Proximity of the sewage sludge land application site to
the wastewater treatment facility is very important in the
decision-making process because of transportation
costs. Further, the cost of sludge dewatering equipment
should be evaluated in view of estimated fuel savings
through decreased total loads and/or shorter haul dis-
tances. For ease of comparison, all costs can be ex-
pressed in dollars per dry weight of sewage sludge.
Capital costs should be estimated over the life of the
site, whereas operating costs should be estimated an-
nually. Cost factors that are of prime importance are
summarized in Table 5-14. These assessments should
be based on experience and best engineering judgment.
Chapter 16 discusses cost estimations in more detail.
5.8.2 Final Site Selection
The Phase I and Phase II site evaluation process should
result in detailed information on two or more sites that
have been identified as suitable for the selected land
application practice. This information, combined with the
preliminary cost analysis (Section 5.8.1) should provide
50
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Technical Assessment and Preliminary Planning
(Chapter 5)
Factors for Consideration
• Regulatory Requirements (federal/state/local)
• Sludge Suitability
• Public Acceptance
• Land Area Requirement
• Transport Feasibility
^~^\
( Practice )
\0nly J
i
Site Evaluation and Selection (Chapters 5 and 6)
Factors for Consideration
• Land Use (current and future)
• Zoning Compliance
• Aesthetics
• Physical Characteristics of Site (soil
characteristics, hydrogeology, etc.)
• Site Acquisition
/""T
\Pr
Two or More
Practlces
Goto
Appropriate
Process Design
Chapter
(Chapters 7
through 10)
Factors for Consideration
• Cost Effectiveness
• Long-Term Environmental Impact
• Other Qualitative Impacts
- Implementability
- Reliability
- Flexibility
- Land-Use Effects
- Public Acceptability
- Legislation
Review the following chapters as necessary
• Process Design Chapters (Chapters 7
through 10)
• Facility Design and Cost Guidance (Chapters 14
and 16)
• Operation and Management (Chapter 15)
Look for
Other
Alternative
S C
\o
Combination
of Practices
Implement the Practice
or the Combination
Figure 5-3. Planning, site selection, and land application practice selection sequence.
51
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Table 5-12. Example Design Features Checklist/Comparison of Candidate Land Application Practices
Candidate Practice or Combination of Practices
Subject Agriculture Forest Reclamation
1. Distance and travel time from POTW to the
candidate site
2. Distance and travel time from the storage
facility to the candidate site
3. Distance from the nearest existing development,
neighbors, etc., to the candidate site
4. Sludge modification requirements, e.g.,
dewatering
5. Mode of sludge transportation
6. Land area required
7. Site preparation/construction needs:
a. None
b. Clearing and grading
c. Access roads (on-site and off-site)
d. Buildings, e.g., equipment storage
e. Fences
f. Sludge storage and transfer facilities
g. On-site drainage control structures
h. Off-site runoff diversion structures
i. On-site runoff storage
j. Flood control structure
k. Ground water pollution control structure,
e.g., subsurface drain system
I.Soil modification requirements,
e.g., lime addition, etc.
8. Equipment needs:
a. Sludge transport vehicle
b. Dredge
c. Pumps
d. Crawler tractor
e. Subsurface injection unit
f. Tillage tractor
g. Sludge application vehicle
h. Nurse tanks or trucks
i. Road sweeper
j. Washing trucks
k. Irrigation equipment
I. Appurtenant equipment
9. Monitoring requirements:
a. Soil
b. Sludge analysis
10. Operational needs
a. Labor
b. Management
c. Energy
d. Repair
52
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Table 5-13. Relative Ranking for Forest Sites for Sewage
Sludge Application3
Table 5-14. Cost Factors To Be Considered During Site
Selection
Factor
Relative Rank
Topography
Slope
less than 10% High
10-20% Acceptable
20-30% Low
over 30% Low
Site continuity (somewhat subjective)
no draws, streams, etc., to buffer High
1 or 2 requiring buffers Acceptable
numerous discontinuities Low
Transportation
Distance Low-High
Condition of the roads Low-High
Travel through sensitive areas Low-High
Forest Access System
Percent of forest system in place Low-High
Ease of new construction
easy (good soils, little slope, High
young trees)
difficult Low-Acceptable
Erosion hazard
little (good soils, little slope) High
great Low-Acceptable
Soil and Geology
Soil type
sandy gravel (outwash, Soil Class I) High
sandy (alluvial, Soil Class II) High
well graded loam (ablation till, Soil Class IV) Acceptable
silty (residual, Soil Class V) Acceptable
clayey (lacustrine, Soil Class IV) Low
organic (bogs) Low
Depth of soil
deeper than 10 ft High
3-1 Oft High
1-3 ft Acceptable
less than 1 ft Low
Geology (subjective, dependent upon aquifer)
sedimentary bedrock Acceptable-High
andesitic basalt Acceptable-High
basal tills Low-Acceptable
lacustrine Low
Vegetation
Tree species
Hybrid cottonwood (highest N uptake rates) High
Douglas-fir High
other conifers High
other mixed hardwoods Acceptable
red alder Low
a basis for selecting the most cost-effective site or sites.
The next section provides an example of the site evalu-
ation and selection process.
5.9 Site Selection Example
Each of the process design chapters (Chapters 7
through 9) provides a detailed example of the design of
Capital Costs
• Land acquisition—purchase, lease, or use of private land.
• Site preparation—grading, roads, fences, drainage, flood
control, and buildings (if needed).
• Equipment—sludge transport and application.
• Sludge storage facilities.
Operating Costs
• Fuel for sludge transport and application.
• Labor (transport, application, maintenance, sampling, etc.)
• Equipment repair.
• Utilities.
• Monitoring, if required (laboratory analysis, sample containers,
shipping).
• Materials and miscellaneous supplies.
a specific land application system for agricultural, forest,
and reclamation sites. This section provides a brief ex-
ample of the site selection procedure that could be used
for a typical medium-sized community.
5.9.1 City Characteristics
• Population-34,000.
• Wastewater volume-0.18 m3/s (4 mgd).
• Wastewater treatment facility description-conven-
tional activated sludge, with anaerobic digestion of
primary and waste-activated sludges.
5.9.2 Sewage Sludge and Soil Characteristics
• Daily sludge generation-2.36 dry t/day (2.6 dry T/day).
• Average solids content-4 percent.
• Average chemical properties (dry weight basis):
- Total N-3 percent
- NH4-N-1 percent
- Total P-2 percent
- Total K-0.5 percent
• Metal regulated by Part 503 (in mg/kg):
-As-10 - Hg-7
- Cd-19 - Mo-12
- Cr-800 - Ni-150
- Cu-700 - Se-19
- Pb-500 - Zn-2,000
• Soil is maintained at pH 6.5 or above when required
for optimum crop production.
5.9.3 Regulations Considered
Assume that agricultural land application is the only
practice being considered, and that special permits are not
required for sewage sludge application, provided that:
53
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1. Annual sewage sludge applications do not exceed either
the agronomic rate or the Part 503 limits for metals.
2. Annual program for routine soil testing (N, P, K) and
lime requirement (pH) is implemented.
3. Wastewater treatment plant measures the chemical
composition of sludge.
4. Records are maintained on the location and the
amount of sludge applied.
5. The site is not 10 meters or less from waters
classified as waters of the United States.
5.9.4 Public A cceptance
Assume that public acceptance of land application of
sewage sludge is judged to be very good. Several
nearby communities have previously established agri-
cultural land application programs with excellent results.
Sewage sludge characteristics from these communities
were similar, as were farm management and cropping
patterns involving corn, oats, wheat, and pastureland.
Several articles had appeared in the local newspaper
indicating that escalating landfill costs were causing the city
to study various sewage sludge use and disposal alterna-
tives. No public opposition groups are known to exist.
i i
r _ ___ _ _ _ _
Figure 5-4. General area map with concentric rings.
5.9.5 Preliminary Feasibility A ssessment
The above preliminary information was sufficiently en-
couraging to warrant further study of agricultural land
application.
5.9.6 Estimate Land Area Required
An application rate of 22.4 t/ha/year (10 T/ac/year) was
used as a first approximation (see Table 5-1). The acre-
age required for the city was estimated as follows:
. . 2.36t/dayx365days/yr
Acreage needed = __ . ... ,—-—— = 38.4 ha
a 22.4 t/ha/yr
Thus, assume 40 ha (100 ac) for the preliminary search.
5.9.7 Eliminate Unsuitable Areas
Figure 5-4 shows a general area map containing the city
and surrounding communities. Three concentric rings of
10, 20, and 30 km (6.2, 12.4, and 18.6 mi) were drawn
around the wastewater treatment facility. Areas directly
south of the facility were immediately excluded because
of the city boundaries. Similarly, areas east and south-
east were excluded because of the city's projected
growth pattern, the encroachment of a neighboring city,
and the municipal airport. Further investigations to iden-
tify potential land application sites were thus concen-
trated to the west and northwest.
LEGEND
DEEP, HELL-DRAINED TO POORLY DRAINED,
MEDIUM TEXTURED AND MODERATELY FINE
TEXTURED, NEARLY LEVEL SOILS THAT
FORMED IN ALLUVIUM
DEEP. SOMEWHAT POORLY DRAINED TO HELL
DRAINED, MEDIUM-TEXTURED, NEARLY LEVEL
TO STEEP SOILS THAT FORMED IN LGESS
AND THE UNDERLYING OUTWASH, IN LOESS
AND THE UNDERLYING GLACIAL TILL OK
IN GLACIAL TILL
MODERATELY DEEP AND DEEP, WELL-DRAINED,
MEDIUM-TEXTURED. GENTLY SLOPING TO STEEP
SOILS THAT FORMED IN LOESS AND THE
UNDERLYING SANDSTONE AND SHALE RESIDUUM
Figure 5-5. General soil map showing area selected for sewage
sludge land application.
54
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5.9.8 Identify Suitable Areas
Soil maps obtained from the local SCS office were exam-
ined within the three radii selected. Areas within the 10-km
(7-mi) ring were given first priority because of their prox-
imity to the wastewater treatment facility. Sufficient land
was located within this distance, and the areas contained
within the second and third radii were not investigated.
Table 5-15. Ranking of Soil Types for Sewage Sludge Application
Depth to
Figure 5-5 is a general soil map showing one potential
area available for sewage sludge land application. A
detailed soil map of the area is shown in Figure 5-6, and
the map legend is presented in Table 5-15.
Information presented in the soil survey report included:
slope, drainage, depth to seasonal water table, and depth to
bedrock. Cation exchange capacities (CEC) were estimated
Soil Type
AvA"
Ca"
CnB2**
CnC2
CnC3
Cn02
Cn03
Fe**
FoA"
FoB2
FoC3
Ge
Hh
La
MbA
MbB2
Md
NgA"
NgB2"
NnA
RnF
Ro"
Rp
RsB2
Sc
Sh"
Sm
Sz
We"
Wh"
Slope
Percent
0-2
0.2
2-6
6-12
6-12
12-18
12-18
0-2
0-2
2-4
6-12
0-2
0-2
0-2
0-2
2-6
0-2
0-2
2-6
0-2
0-2
0-2
0-2
2-6
0-2
0-2
0-2
0-2
0-2
0-2
Seasonal High Bedrock
Water Table (ft) (ft)
1-3 >15
>6 >15
>6 >15
>6 >15
>6 >15
>6 >15
>6 >15
3-6 >15
>6 >15
>6 >15
>6 >15
>6 >15
1-3 >10
>6 >15
>6 >15
>6 >15
3-6 >15
>6 >15
>6 >15
>6 >15
>6 >15
>6 >15
>6 >15
3-6 >15
0-1 >15
1-3 >15
1-3 >15
>6 >15
0-1 >15
1-3 >15
Texture*
sil
sil
sil
sil
sil
sil
sil
sil
I
I
I
I
sil
gsal
I
I
sicl
I
I
I
gi
sicl
sicl
sil
sicl
sil
I
sal
cl
I
Drainage
Class?
P
W
W
W
W
W
W
W
W
W
W
W
SP
W
W
W
MW
W
W
W
E
W
W
MW
VP
SP
SP
W
VP
SP
Approximate
CEC
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
10-15
>5
10-15
10-15
>15
10-15
10-15
10-15
>5
>15
>15
10-15
>15
10-15
10-15
5-10
>15
10-15
Relative
Ranking*
3
1
1
2
2
3
3
2
1
1
2
1
3
1
1
1
2
1
1
1
1
1
1
2
3
3
3
1
3
3
* I, loam; gsal, gravelly sandy loam; sil, silt, loam; sicl, silty clay loam; cl, clay loam; sal, sandy loam; gl, gravelly loam.
f E, excessively drained; W, well drained; MW, moderately well drained, SP, somewhat poorly drained; P, poorly drained; VP, very poorly drained.
* 1, 0-6 percent slope, >6 ft to water table and >15 to bedrock. 2, 6-12 percent slope or 3-6 ft to water table. 3,12-18 percent slope or 0-3 ft to water table.
"Soil types present on potential site (see Figure 5-6). Soil type information from SCS county soil survey.
55
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Wfc
Figure 5-6. Detailed soil survey map of potential site for sew-
age sludge land application. (Areas not suitable for
use are shaded; see Table 5-17 for ranking of soil
types.)
from texture, and a ranking was developed to estimate
soil suitability for sewage sludge application.
Since the detailed soil map was based on an aerial
photo, farm buildings, houses, etc., were usually iden-
tifiable. Certain portions within this area were excluded,
including:
• Areas in close proximity to houses, schools, and
other inhabited buildings.
• Areas immediately adjacent to ponds, lakes, rivers,
and streams.
The excluded areas were shaded (Figure 5-6), using a
mylar overlay. The remaining unshaded areas, covering
about 930 ha (2,300 ac), were generally pastureland with
some fields of corn and oats. Within this area was about
175 ha (432 ac) which ranked in Category 1 in Table 5-15.
The land in the site area was owned by three individuals.
Since the 175 ha (432 ac) was far in excess of the 40 ha
(100 ac) required, no further sites were investigated. Soils
present in the area were generally silt loams. Repre-
sentative soil analysis was as follows:
• CEC - 10 meq/100 g.
• Soil pH - 6.0 (1:1 with water).
• Available P - 16.8 kg/ha (15 Ib/ac).
• Available K - 84 kg/ha (75 Ib/ac).
• Lime necessary to raise pH to 6.5 - 5.4 t/ha (2.4 T/ac).
The three landowners were contacted individually to
determine their willingness to participate. All expressed
considerable interest in participating in the program.
5.9.9 Phase II Site Survey and Field
Investigation
These efforts confirmed the suitability of the site se-
lected. Agreements were thus made with each land-
owner to land apply municipal sewage sludge.
5.9.10 Cost Analysis
No land costs were incurred since the landowners
agreed to accept the sewage sludge. Capital costs in-
cluded: transportation vehicle, application vehicle,
sludge-loading apparatus with pumps, pipes, concrete
pad, electrical controls, and storage facilities. Annual
costs for this system were estimated to be $110/dry t
($98/dry T), as compared to $128/dry t ($116/dry T) for
landfilling the sludge at a site 25 km (15.5 m) from the
wastewater treatment facility.
5.9.11 Final Site Selection
The 175 ha (432 ac) of best quality land were distrib-
uted over seven individual fields, several of which
were not serviced by all-weather roads. These fields
would only be used if complicating factors (e.g., field
or crop conditions) rendered the other fields unusable.
The contractual agreement with the three individuals
specified that sewage sludge would be land applied
to certain fields (to be determined at owner discretion)
at rates commensurate with crop nitrogen require-
ments and in compliance with the Part 503 pollutant
limits for metals and other Part 503, state, and local
regulatory requirements.
5.10 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
Gulp, G., J. Faisst, D. Hinricks, and B. Winsor. 1980. Evaluation of
sludge management systems: Evaluation checklist and supporting
commentary. EPA/430/9-80/001 (PB81108805). Cul/Wesner/Culp,
El Dorado Hills, CA.
Deese, P., J. Miyares, and S. Fogel. 1980. Institutional constraints
and public acceptance barriers to utilization of municipal waste-
water and sludge for land reclamation and biomass production: A
report to the president's council on environmental quality. (EPA
430/9-81-013; July 1981).
Keeney, D., K. Lee, and L. Walsh. 1975. Guidelines for the application
of wastewater sludge to agricultural land in Wisconsin. Technical
Bulletin 88, Wisconsin Department of Natural Resources, Madison, Wl.
Sagik, B., B. Moore, and C. Forber. 1979. Public health aspects
related to the land application of municipal sewage effluents and
sludges. In: Sopper, WE., and S.M. Kerr, eds. Utilization of municipal
sewage effluent and sludge on forest and disturbed land. Pennsyl-
vania State University Press, University Park, PA. pp. 241-263.
U.S. EPA. 1995. Process design manual: Surface disposal of sewage
sludge and domestic septage. EPA/625/R-95/002. Cincinnati, OH.
U.S. EPA. 1984. Environmental regulations and technology: Use and
disposal of municipal wastewater sludge. EPA/625/10-84-003.
Washington, DC.
56
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Chapter 6
Phase II Site Evaluation
6.1 General
The Phase I site evaluation and screening process de-
scribed in Chapter 5 will usually identify a number of
candidate sites for land application of sewage sludge
that require more detailed investigation before final site
selection. The extent and type of information gathered
in field investigations for a Phase II site evaluation will
vary depending on:
• Land application practice being considered, e.g., ag-
ricultural, forest, or land reclamation.
• Regulatory requirements.
• Completeness and suitability of information on soils,
topography, and hydrogeology obtained from other
sources (e.g., the SCS, USGS, etc).
General site characteristics can be obtained from a
combination of soil survey maps and site visits. The
principal soil chemical analyses required are soil tests
which are routinely conducted to develop recommenda-
tions for application of conventional fertilizer materials.
Table 6-1 provides a summary of the site-specific infor-
mation required for different land application practices.
This information is of a general nature and can usually
be obtained from site visits without field sampling and
testing. Review of this information may eliminate some
potential sites from further consideration.
6.2 Preliminary Field Site Survey
A field site survey should be conducted after potential
sites have been identified in the map study performed
during the Phase I site evaluation. A drive or walk
through the candidate areas should verify or provide
additional information on:
• Topography. Estimate of slope both on prospective
site and adjacent plots.
• Drainage. Open or closed drainage patterns.
• Distance to surface water.
• Distance to water supply well(s).
Table 6-1. Basic Site-Specific Information Needed for Land
Application of Sewage Sludge
Property Ownership
Physical Dimensions of Site
a. Overall boundaries
b. Portion usable for sludge land application under constraints
of topography, buffer zones, etc.
Current Land Use
Planned Future Land Use
If Agricultural Crops Are To Be Grown:
a. Cropping patterns
b. Typical yields
c. Methods and quantity of fertilizer application
d. Methods of soil tillage
e. Irrigation practices, if any
f. Final use of crop grown (animal/human consumption,
non-food chain, etc.)
g. Vehicular access within site
If Forest Land:
a. Age of trees
b. Species of trees
c. Commercial or recreational operation
d. Current fertilizer application
e. Irrigation practices
f. Vehicular access within site
If Reclamation Site:
a. Existing vegetation
b. Historical causes of disturbance (e.g., strip mining of coal,
dumping of mine tailings, etc.)
c. Previous attempts at reclamation, if any
d. Need for terrain modification
Surface/Ground Water Conditions
a. Location and depth of wells, if any
b. Location of surface water (occasional and permanent)
c. History of flooding and drainage problems
d. Seasonal fluctuation of ground water level
e. Quality and users of ground water
• Available access roads. All-weather or temporary.
• Existing vegetation/cropping.
A field survey form similar to the one shown in Table 6-2
that records the current condition of all critical factors is
recommended. The data collected from various sites
can then be used to update the map overlay (see Chap-
ter 5). The appropriate additional information for differ-
ent land uses in Table 6-1 (agricultural crops, forest land,
reclamation sites) should also be gathered.
57
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Table 6-2. Sample Form for Preliminary Field Site Survey
A. PROPERTY LOCATION PROPERTY OWNER
TOPOGRAPHY
1. Relief (sharp, flat, etc.).
2. Slope Estimate
3. Drainage Patterns
- Open/Closed
- Drainage Class No.*
-Any Underdrains
DISTANCE FROM SITE BOUNDARY TO:
1. Surface Water
2. Water Supply Well
ESTIMATE OF SITE DIMENSIONS
1. Area
2. Natural Boundaries
3. Fences
E.
AVAILABLE ACCESS
1. Road Types
2. Other
G.
EXISTING VEGETATION/CROPS AND COMMONLY USED
CROP ROTATIONS
1. On-Site
2. Neighboring Properties
SOIL
1. Texture
2. Variability
•Refer to Soil Conservation Service drainage classes.
6.3 Site-Specific Field Investigations
This section focuses on basic field investigation meth-
ods applicable to agricultural and forest land application
sites, which typically encompass areas of tens to hun-
dreds of hectares, but for which detailed maps (1:6,000
or less) generally are not available. In general, active
reclamation sites often have detailed maps and exten-
sive environmental data that have been prepared and
collected as part of the permitting process, so specific
additional information for determining sewage sludge
application rates may not be required. Section 6.5 dis-
cusses special considerations related to investigation of
reclamation sites involving abandoned land.
Where land application of bulk sewage sludge is being
considered for public contact sites, such as parks, de-
tailed site maps may be available that can be used for
the type of investigations described here. Otherwise,
field investigation procedures described in this section
are applicable. Application of bagged sewage sludge on
public contact sites, lawns, and home gardens will not
require site-specific field investigations.
6.3.1 Base Map Preparation
Major types of commonly available maps that contain
useful information for site field investigations include
(1) U.S. Geological Survey (USGS) 7.5 minute topo-
graphic maps (scale 1:24,000), (2) published Soil Con-
servation Service (SCS) soil survey maps (which usually
range in scale from 1:15,000 to 1:20,000), (3) Federal
Emergency Management Agency (FEMA) floodplain
maps, and (4) U.S. Fish and Wildlife Service National
Wetland Inventory Maps.
Site boundaries from a recent survey or County records
should be located as accurately as possible on all maps
that have been collected for the site. The accuracy of
points on a USGS 7.5 minute quadrangle map (about
plus or minus 50 feet) is generally not sufficient for
detailed site evaluation for sewage sludge land applica-
tion, but the expense of preparing a larger scale topo-
graphic base map will usually not be justified. Enlarging
the area of a topographic map that includes the site of
interest using a copy machine is the simplest way to
obtain a larger scale working map for field investiga-
tions. The same can be done for a soil map of the area,
if available. The original scale bars of the map should
be included or enlarged separately so that the actual
scale of the enlarged map can be determined. Informa-
tion from other maps, such as flood plain boundaries,
should also be transferred to the working base map.
Another way to obtain a larger scale topographic base
map, if the computer equipment and software are avail-
able, is to obtain the appropriate USGS map in digital
format, which then can be used to print a base map of
the desired area and scale.
6.3.2 Field Checking of Surface Features and
Marking Buffer Zones on the Base Map
Key point and linear surface features on the base map
that should be added or checked in the field include:
(1) location of surface water features (springs, inter-
mittent and perennial surface streams, ponds and
streams); (2) location of ground water wells, and (3)
location of residences, other buildings, public roads,
fencelines and other man-made features. Accuracy of
surface features on the enlarged base map can be
checked by first measuring distances between points on
the map that can be easily located in the field, and then
measuring the actual distance. For example, measuring
the distance of a site corner by a roadway from the point
that a stream crosses the site boundary at the road is
relatively easy to measure in the field by pacing or using
a 100-ft tape measure. Any major features that are not
within about 10 feet of the marked location on the en-
larged topographic base map should be redrawn. Also,
58
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any significant surface features that are not on the base
map should be added.
The field-checked and revised base map allows reason-
ably accurate delineation of any buffer zones where
sewage sludge should not be applied. The Part 503 rule
specifies a minimum buffer of 10 meters from surface
waters at a land application site unless otherwise speci-
fied by the permitting authority. Many states specify
larger buffers to surface waters and may specify buffers
to wells, dwellings, property lines, and other features.
Any applicable setback distances should be marked on
the field-checked base map.
6.3.3 Identifying Topographic Limitations
Many state regulatory programs define slope grade lim-
its for land application of sewage sludge that may vary
according to the type of land use (e.g., agricultural,
forest, or reclamation site) and method of application
(Table 5-8). The appropriate regulatory authority should
be contacted to identify any slope limitations that might
apply to the site. An SCS soil survey (see Section 6.3.4)
is the easiest way to identify areas with similar slope
ranges because soil map units are usually differentiated
according to slope classes. Soil map units with slopes
that exceed the applicable limitations should be marked
as potentially unsuitable areas before going into the
field. Depending on the type of soil or application
method (e.g., surface application, incorporation, or in-
jection), different slopes may be appropriate. Areas with
differing slope limits should be identified on the same
map; alternatively, separate maps may be developed
that identify potentially unsuitable areas because of dif-
fering slope limitations.
The above map(s) needs to be taken into the field to
check the accuracy of the boundaries separating suit-
able and unsuitable areas based on slope. In most
situations, spot checking of actual slope gradients using
a clinometer and a surveyor's rod will be adequate
(Boulding, 1994 and U.S. EPA, 1991 describe this pro-
cedure in more detail). Such field checking is likely to
result in slight to moderate adjustments to the bounda-
ries delineating areas with unsuitable slopes. The field-
checked topographic boundaries should be marked on the
enlarged topographic base map described in Section 6.3.1.
6.3.4 Field Soil Survey
If available, a county soil survey published by the SCS
is the best single source of information about a site
because it also provides an indication of subsurface
geologic and hydrogeologic conditions and contains a
wealth of information on typical soil physical and chemi-
cal characteristics. If a soil survey is not available, check
to see if the current or previous property owners have
worked with the local Soil and Water Conservation Dis-
trict. If so, an unpublished farm survey may be on file in
the District SCS office. If an unpublished soil survey is
available, SCS soil series descriptions and interpretation
sheets should be obtained for all soil series that have
been mapped in the area (see Table 6-3). Estimated soil
properties are typically given as ranges or values for
different soil horizons; direct field observation and sam-
pling are required for more accurate definition of soil
properties. Even if a published soil survey is available,
Table 6-3. Types of Data Available on SCS Soil Series
Description and Interpretation Sheets
Soil Series Description Sheet
Taxonomic Class
Typical soil profile description
Range of characteristics
Competing series
Geographic setting
Geographically associated soils
Drainage and permeability
Use and vegetation
Distribution and extent
Location and year series was established
Remarks
Availability of additional data
Soil Survey Interpretation Sheet*
Estimated Soil Properties (major horizons)
Texture c/ass(USDA, Unified, and AASHTO)
Particle size distribution
Liquid limit
Plasticity index
Moist bulk density (g/cm3)
Permeability (in/hr)
Available water capacity (in/in)
Soil reaction (pH)
Salinity (mmhos/cm)
Sodium absorbtion ratio
Cation exchange capacity (Me/100g)
Calcium carbonate (%)
Gypsum (%)
Organic matter (%)
Shrink-swell potential
Corrosivity (steel and concrete)
Erosion factors (K, T)
Wind erodability group
Flooding (frequency, duration, months)
High water table (depth, kind, months)
Cemented pan (depth, hardness)
Bedrock (depth, hardness)
Subsidence (initial, total)
Hydrologic group
Potential frost action
Use/Suitability Ratings
Sanitary facilities
Source material
Community development
Water management
Recreation
Crop/pasture capability and predicted yields
Woodland suitability
Windbreaks (recommended species for planting)
Wildlife habitat suitability
Potential native plant community (rangeland or forest)
* Units indicated are those used by SCS.
Note: Italicized entries are particularly useful for evaluating contami-
nant transport.
59
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these sheets provide a convenient reference for charac-
teristics of soil series occurring within a site. The same
information on individual soil series can be found in the
text portion of an SCS soil survey, but is scattered
through different sections and tables in the report.
Although published soil surveys provide much useful
information for preliminary site selection, they may not
be adequate for site-specific evaluation for land applica-
tion of sewage sludge. For example, areas of similar
soils that cover less than 4 or 5 acres are generally not
shown on published SCS county soil surveys. For site-
specific evaluation and design purposes, it is desirable
to identify areas of similar soil characteristics that are as
small as an acre. The SCS may be able to prepare a
more detailed soil survey of a site that has been selected
for land application of sewage sludge. If SCS has a large
backlog of requests, however, obtaining a more detailed
soil survey can take months. A detailed soil survey
prepared by consulting soil scientists will be more ex-
pensive, but will usually involve less delay. If a private
consultant conducts the soil survey, the person or per-
sons actually carrying out the survey should be trained
in soil mapping and classification methods used by SCS
for the National Cooperative Soil Survey.
Field checking of soil map unit boundaries and deline-
ation of smaller units omitted from an existing SCS soil
survey can be done using an enlarged soil map, as
described for the topographic base map in Section 6.3.1.
Alternatively, revised soil map unit delineations or new
mapping can be done directly on the working topo-
graphic base map. An added benefit of more detailed
soil mapping at a site is that it will also provide additional
site-specific information for delineation of floodplains
and wetlands (Section 6.3.5), and for hydrogeologic
interpretations where ground-water is relatively shallow
(Section 6.3.6). The soil survey will also be helpful in
planning soil sampling for designing agronomic rates of
sewage sludge application (Section 6.4).
6.3.5 Delineation of Floodplains and
Wetlands
Some state regulatory programs place restrictions or
limitations on land application of sewage sludge on or
near floodplains and wetlands. State floodplain restric-
tions vary, ranging from prohibition of application on the
10-year or 100-year floodplain, to conditions on place-
ment within a floodplain (e.g., incorporation within 48
hours, use of diversion dikes or other protective meas-
ures). Floodplains can be easily identified as low-lying
areas adjacent to streams on topographic maps and as
alluvial soils adjacent to streams on soil maps. FEMA
maps should be consulted to determine whether a site
includes a 100-year floodplain. Accurate delineation of
floodplain boundaries requires detailed engineering and
hydrologic studies. The appropriate regulatory agency
should be consulted to determine whether such detailed
investigations are required, and, if so, to identify recom-
mended procedures.
Wetlands include swamps, marshes, bogs, and any ar-
eas that are inundated or saturated by ground water or
surface water at a frequency and duration to support a
dominant vegetation adapted to saturated soil condi-
tions. As with floodplains, an SCS soil survey will indi-
cate whether "hydric" soils are present at a site (e.g.,
soils that are wet long enough to periodically produce
anaerobic conditions). If wetlands are present at a site,
the appropriate regulatory agency should be contacted
to determine whether their boundaries should be accu-
rately delineated.
Accurate wetland delineation typically requires assess-
ment by a qualified and experienced expert in soil sci-
ence and botany/biology to identify: (1) the limits of the
wetland boundary based on hydrology, soil types, and
plants types; (2) the type and relative abundance of
vegetation, including trees; and (3) rare, endangered, or
otherwise protected species and their habitats, if pre-
sent. Many methods have been developed for assess-
ing wetlands. The main guidance manuals for wetland
delineation for regulatory purposes are the Corps of
Engineers Wetlands Delineation Manual (U.S. Army
Corps of Engineers, 1987) and the Federal Manual for
Identifying and Delineating Jurisdictional Wetlands
(Federal Interagency Committee for Wetland Deline-
ation, 1989). The latter manual places greater emphasis
on assessment of the functional value of wetlands,
along the lines of earlier work by the U.S. Fish and
Wildlife Service (U.S. Fish and Wildlife Service, 1984).
6.3.6 Site Hydrogeology
The Part 503 rule does not explicitly require investiga-
tions to characterize ground-water hydrology at sewage
sludge land application sites but does require that sew-
age sludge be land applied at the agronomic rate for N
for the crop or vegetation being grown. As discussed in
Section 6.4.1 on agronomic rates, some knowledge of
depth to ground water is useful when selecting appro-
priate sites. Tables 5-9 and 5-10 contain general guide-
lines for depth to ground water at land application sites.
Most states have established their own requirements for
minimum depths to ground water for sewage sludge
land application sites, which range from 1 ft to 6 ft. Also,
a number of states restrict application on highly perme-
able and/or very slowly permeable soils.
The field soil survey described in Section 6.3.4 will
provide the necessary information on depth to ground
water for most sites. The published soil survey report or
soil series interpretation sheet will indicate typical
depths to seasonal high water table and also expected
ranges of permeability for each major soil horizon. If
significant areas of the site have relatively shallow water
60
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tables (<3 feet), it may be desirable to prepare a more
detailed depth-to-water-table map based on soil mor-
phology, as described below. Soils with very high or very
slow permeability, as indicated by the soil survey, should
be eliminated as areas for land application of sewage
sludge, if possible. If elimination of such areas places
too great a restriction on suitable areas for land applica-
tion, it may be necessary to conduct field infiltration and
permeability tests to determine whether areas of these
soils may be suitable.
6.4 Soil Sampling and Analysis to
Determine Agronomic Rates
6.4.1 Part 503 Definition of Agronomic Rate
Designing the agronomic rate for land application of
sewage sludge is one of the key elements in the Part
503 rule for ensuring that land application does not
degrade ground water quality through nitrate contami-
nation. The Part 503 rule defines agronomic rate as:
the whole sludge application rate (dry weight
basis) designed: (1) to provide the amount of
nitrogen needed by the food crop, feed crop, fiber
crop, cover crop, or vegetation grown on the land
and (2) to minimize the amount of nitrogen in the
sewage sludge that passes below the root zone of
the crop or vegetation grown on the land to the
ground water. (40 CFR 503.11 (b))
Designing the agronomic rate for a particular area re-
quires knowledge of (1) soil fertility, especially available
N and P; and (2) characteristics of the sewage sludge,
especially amount and forms of N (organic N, NH4, and
NO3). The complex interactions between these factors
and climatic variability (which affects soil-moisture re-
lated N transformations) make precise prediction of crop
N requirements difficult.
Nitrogen fertilizer recommendations have historically
been based primarily on experience from replicated
field trials of crop response on different soil types and
management practices. Nitrogen fertilizer recommen-
dations based on such studies often vary regionally.
The high organic N content of sewage sludge, which
becomes available for plant uptake over a period of
years as it is gradually mineralized, requires an
approximate mass balance that accounts for N needs
of the crop, availability of N in the sewage sludge and the
soil, and losses (such as volatilization and denitrification).
Chapter 7 and Chapter 8 address in detail mass balance
methods for designing agronomic rates at agricultural
and forest sites.
6.4.2 So/7 Sampling
Soil sampling and analysis will usually not be needed at
land application sites until the site has been selected
and it is time to calculate sewage sludge application
rates. Soil sample collection procedures are described
in Chapter 13. The types of analyses performed on soil
samples will vary somewhat depending on the crop and
state regulatory requirements. Major constituents that
may need to be tested include:
• NO3-N as an indicator of plant-available N in the soil.
NO3 root zone profiles are widely used in states west
of the Missouri River where precipitation and leaching
are relatively low (Keeney, 1982). The pre-sidedress
nitrate test (PSNT), where soil NO3-N is sampled to
a depth of 0.3 to 0.6 m prior to corn planting or in
early June, has been found to be a good indicator of
plant-available N in humid areas (Magdoff et al.,
1984; Sander et al., 1994). Where applicable, these
tests should be made for calculating initial sewage
sludge application rates, and can possibly be used
in subsequent years as a more accurate alternative
to the equations in Chapters 7 and 8 for estimating
N mineralization rates. Chapter 13 discusses these
tests in more detail.
• C:N ratio, which provides an indication of the poten-
tial for immobilization of N in sewage sludge as a
result of decomposition of plant residues in the soil
and at the soil surface. This is especially relevant for
forest land application sites, as discussed in Chapter 8.
• Plant-available P. Where sewage sludge is applied at
rates to supply plant N needs, this test is less critical.
This test is essential, however, if sewage sludge ap-
plication rates are to be based on plant P require-
ments (see Chapter 7).
• Plant-available K. This is required to determine supple-
mental K fertilization needs for optimum plant growth.
• Soil pH and pH (e.g., lime) adjustments. A soil pH of
approximately 6.5 maximizes the availability of soil
nutrients to plants and immobilization of trace metals.
Where soil pH is lower than 6.5, lime or other alkali
amendments are often added to the soil to bring pH
to the desired level.
6.5 Special Considerations for
Reclamation Sites
At reclamation sites involving abandoned mined land,
field investigations to characterize ground-water distri-
bution and quality are usually required. The detailed site
investigation should determine the following:
• Depth to ground water, including seasonal variations
• Quality of existing ground water
• Present and potential future use of ground water
• Existence of perched water
• Direction of ground water flow
61
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6.5.1 Sampling and Analysis of Disturbed Soils
Sampling and analysis of soils at reclamation sites are
necessary to:
• Establish sewage sludge application rates (typically
for a single or several [e.g., three] application(s) at
reclamation sites).
• Determine amounts of supplemental fertilizer, lime,
or other soil amendment required to obtain desired
vegetative growth.
• Determine the infiltration and permeability charac-
teristics of the soil.
• Determine background soil pH, metals, nutrients,
etc., prior to sewage sludge application.
Soil survey maps will usually provide only an idea of the
type of soil present prior to the disturbance. Often, the
only soil profile present on a surface-mined site is the
mixture of soil and geologic materials, and the physical
and chemical characteristics of the mixture can vary
greatly over relatively short distances. A field inspection
will need to be made to determine the number and
location of samples necessary to characterize the ma-
terials. The specific analyses needed may vary from
location to location based on state and local regulations
covering both the reclamation and sewage sludge land
application aspects. Chapter 13 describes disturbed soil
sampling procedures further.
Nitrogen and phosphorus are generally deficient on
disturbed lands, and phosphorus is often the most
limiting fertility factor in plant establishment on drasti-
cally disturbed land (Berg, 1978). Soil tests used for
P analysis reflect the chemistry of soils, and thus are
more regionalized than tests for other major nutrients.
A number of soil tests have been developed for use
on acid soils in the eastern United States and on
neutral and calcareous soils in the west. Drastically
disturbed lands, however, do notalways reflect the local
soils. Thus, if disturbed spoil material is going to be
analyzed for P, the local routine analysis procedure may
not be appropriate, and other P analyses might be re-
quired. Recommendations should be obtained from the
local agricultural experiment station. Testing for pH re-
quires sufficient sampling of surface soils to charac-
terize variations in pH; coring may be required to identify
any subsurface distribution of toxicor acid-forming spoil
material.
6.6 References
Berg, W.A. 1978. Limitations in the use of soil tests on drastically
disturbed lands. In: F.W. Schallerand P. Sutton, eds. Reclamation
of drastically disturbed lands, American Society of Agronomy,
Madison, Wl. pp. 563-664.
Boulding, J.R. 1994. Description and sampling of contaminated soils:
A field guide, 2nd ed. Chelsea, Ml: Lewis Publishers.
Federal Interagency Committee for Wetland Delineation. 1989. Fed-
eral manual for identifying and delineating jurisdictional wetlands.
Cooperative Technical Publication, U.S. Army Corps of Engineers,
U.S. Environmental Protection Agency, U.S. Fish and Wildlife
Service, and U.S. Department of Agriculture Soil Conservation
Service, Washington, DC.
Keeney, D.R. 1982. Nitrogen-availability indices. In: A.L. Page, ed.
Methods of soil analysis, part 2, 2nd ed. American Society of
Agronomy, Madison, Wl. pp. 711-733.
Magdoff, F.R., D. Ross, and J. Amadon. 1984. A soil test for nitrogen
availability to corn. Soil Sci. Soc. Am. J. 48:1301-1304.
Sander, D.H., D.T. Walthers, and K.D. Frank. 1994. Nitrogen testing for
optimum management. J. Soil and Water Conserv. 49(2):46-52.
U.S. Army Corps of Engineers. 1987. Wetlands delineation manual. Tech-
nical Report Y-87-1. Waterways Experiment Station, Vicksburg, Ml.
U.S. EPA. 1991. Description and sampling of contaminated soils: A
field pocket guide. EPA/625/2-91/002. Cincinnati, OH.
U.S. Fish and Wildlife Service. 1984. An overview of major wetland
functions and values. FWS/OBS-84/18. Washington, DC.
62
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Chapter 7
Process Design for Agricultural Land Application Sites
7.1 General
Agricultural land is the type of land most widely used for
the application of sewage sludge. This chapter presents
detailed design information for the application of sewage
sludge to agricultural land, placing primary emphasis on
the growing of crops such as corn, soybeans, small
grains, cotton, sorghum, and forages. The design exam-
ple presented at the end of this chapter assumes that
the designer has (1) selected agricultural land applica-
tion; (2) completed preliminary planning (see Chapter
5); and (3) chosen a transportation system to convey
sewage sludge to the application site (see Chapter 14).
The design approach presented in this chapter is based
on the use of sewage sludge as a low-nutrient fertilizing
material that can partially replace commercial fertilizers.
The goal of this approach is to optimize crop yields
through applications of both sewage sludge and supple-
mental fertilizers, if needed. The sewage sludge appli-
cation rate is typically designed for either the nitrogen
(N) or phosphorus (P) needs of the crop grown on a
particular soil. In addition, the sewage sludge applica-
tion rate must be consistent with federal, state, and local
regulations relative to pathogens, metals, and organics
contained in the sewage sludge and related require-
ments for vector attraction reduction.
The design example presented at the end of this chapter
also assumes that basic sewage sludge and crop produc-
tion information has been collected. The sewage sludge
composition data needed to meet regulatory requirements
and ensure good design are described in Chapter 4.
Other concerns regarding agricultural land application in-
clude the possibility of odors or potential exposure to
pathogens due to inadequate sewage sludge treatment or
poor site management. The design approach described in
this chapter assumes that the sludge has been properly
stabilized to meet pathogen and vector attraction reduction
requirements and reduce odor potential.
Community acceptance of a land application project will
be more readily forthcoming if local participation is assured.
The initial task for obtaining public support begins with
the selection of a project team whose members can offer
technical service and expertise (see Chapter 12).
Information must also be available on the types of crops
to be grown, attainable yield level, and the relationship
between soil fertility tests and recommended fertilizer ap-
plication rates. The overall goal is to develop a nutrient
management plan for the use of sewage sludge and fertil-
izer to meet the nutrient needs of the crop to be grown.
7.2 Regulatory Requirements and
Other Considerations
Chapter 3 presents the requirements specified by the
federal Part 503 regulation. When designing a land
application system, check with state and local agencies
to learn about any other requirements that must be met.
Information on other key design considerations, such as
nutrients, pH, and land application of sewage sludge on
arid lands, is discussed below.
7.2.1 Nitrogen and Other Nutrients
7.2.1.1 Nitrogen
Nitrogen is the nutrient required in the largest amounts by
all crops. The addition of N to soils in excess of crop needs
results in the potential for NOa-N contamination of ground
water because NO3-N is not readily adsorbed by soil
particles and will move downward as water percolates
through the soil profile. Whether excess N is applied by
sewage sludge or from excessive applications of animal
manures or conventional N fertilizer materials, an in-
creased risk of NO3-N loss to ground water may occur,
depending on climate or crop production practices. High
NO3-N levels in water supplies may result in health prob-
lems for both infants and livestock (Reed et al., 1994). The
maximum allowable concentration of NO3-N in drinking
water has been established at 10 mg/L NCVN.
To prevent ground-water contamination by NO3-N, the
Part 503 rule requires that bulk sewage sludge be ap-
plied to a site at a rate that is equal to or less than the
agronomic rate for N at the site. This is the rate that is
designed to provide the amount of N needed by the crop
while minimizing the amount of N in the sewage sludge
63
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that will pass below the root zone of the crop to the
ground water. The factors that must be considered in
deriving the agronomic application rate for a crop site
include, but are not limited to:
• The amount of N needed by the crop or vegetation
grown on the land.
• The amount of plant-available N remaining from pre-
vious applications of N-containing materials (e.g., fertil-
izers, irrigation water, animal manure, sewage sludge).
• The amount of organic N that is mineralized and
becomes available each year from previous applica-
tions of N-containing materials (e.g., sewage sludge,
animal manure).
• The amount of N left from biological N fixation by
leguminous crops that is mineralized and becomes
available for crops to use (i.e., legume credit).
• The type of soil at the site and the amount of N
mineralized from soil organic matter.
• Denitrification losses of NO3-N and/or volatilization
losses of ammonia.
• Any other identifiable sources or losses of N.
The design example in Section 7.5 illustrates the process
for calculating the agronomic rate.
7.2.1.2 Phosphorus
For most sewage sludge, applying sufficient sludge to
meet all the crop's N needs will supply more P than
needed (Jacobs et al., 1993). Phosphorus does not
usually present a ground-water pollution concern. Some
states limit sludge application to cropland based on P
loading to protect surface water quality. Section 7.4.4.2 and
7.5.3 discuss sewage sludge application rates limited by P.
7.2.1.3 Other Nutrients
Sewage sludge application can be a source of micronu-
trients that are important for plant growth, such as iron
(Fe), manganese (Mn), and zinc (Zn). But because sew-
age sludge does not contain balanced amounts of nutri-
ents, an understanding of agronomy and crop production
practices is important to prevent possible disruption of soil
fertility and plant nutrition when sludge is applied to crops
(Jacobs etal., 1993). For example, at an agricultural site
in Virginia, addition of lime-treated sludge raised the soil
pH to 7.5, resulting in manganese deficiency in soybeans.
The problem was corrected by application of Mn to foliage,
and the POTW eliminated lime conditioning to prevent ex-
cessive elevation of soil pH caused by sewage sludge
applications (Jacobs et al., 1993).
7.2.2 So/7 pH and Requirements for pH
Adjustment
Some states require that soils treated with sludge be
maintained at a pH of 6.5 or above to minimize the
uptake of metals by crops based on previous EPA guid-
ance. The federal Part 503 regulation does not require
a minimum pH of soil because pH was factored into the
risk assessment on which the regulation was based
(U.S. EPA, 1992). In addition, at least one review of the
literature on how soil pH influences the uptake of metals
suggests that the recommendation of pH 6.5 should be
reconsidered for food-chain agricultural soils, based on
reports that indicate adequate control of metals uptake
at pH 6.0 (Sommers et al., 1987). As discussed above
(Section 7.2.1.3), proper management of soil pH also is
important for good nutrient availability and crop growth.
Soil pH control has been practiced routinely in those
areas of the United States where leguminous crops
(e.g., clover, alfalfa, peas, beans) are grown. Fortu-
nately, limestone deposits are normally abundant in
these regions, resulting in minimal costs associated with
liming soils. Considerable cost, however, may be asso-
ciated with liming soils in other areas of the United
States (e.g., eastern and southeastern states). Soils in
these regions tend to be naturally acidic, and may re-
quire relatively large amounts of limestone (12 to 20
t/ha, or 5 to 8 tons/ac [T/ac]) to maintain a proper soil
pH. In addition, the trend toward increased growth of
cash grain crops (corn, small grains) has resulted in
greater commercial fertilizer use, which generates acid-
ity that can decrease soil pH.
While maintaining soil pH between 6.5 and 7.0 often is
desirable for optimum availability of essential plant nu-
trients, liming soils is not always necessary to achieve
desired crop growth. For example, excellent yields of
corn, soybeans, and wheat can be obtained at a soil pH
of 5.5 to 6.0. Many soils in most of the western United
States contain free calcium carbonate, which naturally
maintains a pH of about 8.3. For these types of soils, trace
element deficiencies rather than toxicities are a major
concern. Therefore, the best advice is to involve agro-
nomic expertise to help manage soil pH at the recom-
mended levels for soils and crops in your state or area.
Soil pH is buffered by inorganic and organic colloids.
Thus, it does not increase immediately after limestone
applications, nor does it decrease soon after sewage
sludge or N fertilizer additions. If soil pH is less than the
desired level, a lime requirement test can be used to
estimate the amount of agricultural limestone required
to adjust the pH. Soil pH monitoring is discussed further
in Chapter 13.
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7.2.3 Special Considerations for Arid Lands
7.2.3.1 Crop Land
In arid regions (all U.S. lands west of the 100th meridian,
with less than 20 inches of rain annually), sewage
sludge additions can be a significant source of nutrients
and organic matter. Sludge application can often im-
prove soil physical properties such as water-holding
capacity, infiltration, and aeration (Burkhardt et al.,
1993). Sludge application can also increase the protein
content of crops such as winter wheat compared to sites
receiving commercial N fertilizer (Ippolito et al., 1992).
In arid and semi-arid climates, evapotranspiration ex-
ceeds precipitation, minimizing downward migration of
NO3-N. In low-rainfall and irrigated areas, sewage
sludge constituents such as soluble salts and boron (B)
should also be considered when determining sludge
application rates. High concentrations of salt in the plow
layer can impair germination and early seedling growth
(Jacobs et al., 1993). Excessive salt can also cause soil
dispersion, reducing water infiltration rates and soil
aeration and causing soil structure changes that make
tilling more difficult (Jacobs et al., 1993).
Generally, additions of salts by sewage sludge applica-
tions at agronomic rates will be low enough to avoid any
salt injury to crops. In dry climates, however, sewage
sludge can be a source of additional salts to the soil-
plant system, as can other fertilizers, manures, etc. Salt
sources must be properly managed if optimum crop
growth is to be achieved. Therefore, guidance from land
grant universities or other local sources of agronomic
information should be sought to help manage soluble
salt levels in soils.
7.2.3.2 Rangeland
Application of sewage sludge to rangeland (open land
with indigenous vegetation) is considered agricultural
land application under the Part 503 regulation. Much of
the arid and semiarid rangelands in the western and
southwestern United States have been degraded by
overgrazing, fires, wind erosion, and single resource
management practices. Sewage sludge application to
these lands can enhance the soil and vegetation
(Aguilar et al., 1994). Benefits can include increased
rangeland productivity; improved forage quality; in-
creased rainfall absorption and soil moisture; reduced
runoff; increased germination and populations of favor-
able grasses; less competition from invading shrubs and
weeds; and decreased erosion potential (Fresquez et
al., 1990; Pierce et al., 1992; Peterson and Madison,
1992). In addition, the remote locations of most arid
rangeland sites minimizes public concerns about odors,
vectors, and traffic. Table 7-1 describes projects in which
sewage sludge was applied to arid rangelands.
As Table 7-1 shows, various studies concur that sewage
sludge application to rangelands can improve plant pro-
ductivity without adversely impacting the environment.
The studies vary, however, regarding what application
rates of sewage sludge are optimum to use. A study in
Fort Collins, Colorado, reported that an application rate
of 4.5 mg/ha (2 dry T/ac) would enhance vegetative
growth with minimum excess NO3-N concentrations in
soil (RDB and COM, 1994), and also indicated that N
levels in soil did not increase at a soil depth of 12 inches
as application rates increased (Gallier et al., 1993). A
study in the Rio Puerco Watershed in New Mexico indi-
cated that leaching from saturated flow would not be
expected to occur below 1.5 m (5 ft) in similar soils in
this semiarid environment (Aguilar and Aldon, 1991).
Another study in Wolcott, Colorado, reported potential
NO3-N in surface water runoff at application rates above
20 mg/ha (9 dry T/ac), while a study at the Sevilleta
National Wildlife Refuge in New Mexico reported a re-
duction in surface water runoff at an application rate of
45 mg/ha (20 dry T/ac), with NO3-N, copper (Cu), and
cadmium (Cd) concentrations in the runoff below state
limits for ground water and for livestock and wildlife water-
ing areas (Aguilar and Aldon, 1991).
A key to successful sewage sludge application on arid
rangelands is minimizing the disturbance of soil and
vegetation. Once the plant cover is disturbed, recovery
is very slow in the arid conditions, leaving the rangeland
vulnerable to erosion and weed invasion (Burkhardt et
al., 1993). Section 7.3.1 below discusses sludge appli-
cation methods suitable for arid rangelands.
7.3 Application Methods and Scheduling
7.3.1 Application Methods
Methods of sewage sludge application chosen for agri-
cultural land depend on the physical characteristics of
the sludge and soil, as well as the types of crops grown.
Liquid sewage sludge can be applied by surface spread-
ing or subsurface injection. Surface application methods
include spreading by farm tractors, tank wagons, special
applicator vehicles equipped with flotation tires, tank
trucks, portable or fixed irrigation systems, and ridge
and furrow irrigation.
Surface application of liquid sludge by tank trucks and
applicator vehicles is the most common method used for
agricultural croplands, particularly when forage crops
are grown. Surface application of liquid sludge is nor-
mally limited to soils with less than a 6 percent slope.
Afterthe sludge has been applied to the soil surface and
allowed to partially dry, it is commonly incorporated by
plowing or other tillage options prior to planting the crop
(i.e., corn, soybeans, small grains, cotton, other row
crops), unless minimum or no-till systems are being used.
Ridge and furrow irrigation systems can be designed to
65
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Table 7-1. Summary of Research on Sewage Sludge Application to Rangeland (Adapted From U.S. EPA, 1993)
Geographic Location Plant Community
Mean Precip.
(cm/yr)
Sludge Loading
(mg/ha, dry) Significant Results of Study
Wolcott, CO
Meadow Springs Ranch,
Fort Collins, CO
Sevilleta National
Wildlife Refuge, NM
Rio Puerco
Watershed, NM
western wheatgrass,
alkali bluegrass,
Indian ricegrass
25
blue grama,
buffalo grass,
western wheatgrass,
fringed sage
blue grama,
hairy grama
blue grama,
snakeweed
38
20-25
25
0, 4.5, 9, 13, 18, Increase in species diversity with sewage
22, 27, 31, 36 sludge application. Increase in nitrogen
concentration in soil profile with increasing
application rates, but did not penetrate below
90 cm (about 3 ft). Application rates above
20 mg/ha (9 T/ac) pose a potential hazard for
surface water contamination by nitrates (Gallier
et al., 1993; Pierce, 1994).
0, 2.2, 4.5, 11, Maximum vegetative growth was obtained at
22, 34 an application rate of 11 mg/ha (5 T/ac). An
application rate of 4.5 mg/ha (2 T/ac) of
sewage sludge would increase vegetative
growth and minimize excess nitrate
concentrations in soil (RDB and COM, 1994).
Nitrogen levels in soil ceased to increase
below 1 ft (Gallier et al., 1993).
45 Reduction in runoff volumes due to increased
water absorption and surface roughness
resulting from sewage sludge application.
Nitrate concentrations in runoff were well below
recommended NM standard of 10 mg-N/l
(Aguliar and Loftin, 1991; Aguilar et al, 1992).
0, 22.5, 45, 90 An increase of 2 to 3 fold in blue grama forage
production was found for sludge applications of
45 and 90 mg/ha (20 and 40 T/ac). A decrease
in snakeweed yield was found, allowing forage
to increase (Fresquez et al., 1991). Sludge
applications of 22.5 and 45 mg/ha (10 and 20
T/ac) produced the most favorable vegetative
growth responses, whereas applications of 90
mg/ha (40 T/ac) did not significantly increase
yield (Fresquez et al., 1990).
apply sewage sludge during the crop growing season.
Spray irrigation systems generally should not be used
to apply sludge to forages or to row crops during the
growing season, although a light application to the stub-
ble of a forage crop following a harvest is acceptable.
The adherence of sludge to plant vegetation can have
a detrimental effect on crop yields by reducing photo-
synthesis. In addition, spray irrigation tends to increase
the potential for odor problems and reduces the aesthet-
ics at the application site, both of which can lead to
public acceptability problems.
Liquid sewage sludge can also be injected below the soil
surface, and injection generally is the preferred method
when gaining public acceptance. Available equipment
includes tractor-drawn tank wagons with injection
shanks (originally developed for liquid animal manures)
and tank trucks fitted with flotation tires and injection
shanks (developed for sludge application). Both types of
equipment minimize odor problems and reduce ammo-
nia volatilization by immediate mixing of soil and sludge.
Sludge can be injected into soils with up to 12 percent
slopes. Injection can be used either before planting or
after harvesting most crops but is likely to be unaccept-
able for forages and sod production. Some injection
shanks can damage the sod or forage stand and leave
deep ruts in the field. Equipment with specialized injec-
tion shanks has been developed that will not damage
the growth of forage and sod crops.
Dewatered sewage sludge can be applied to cropland
by equipment similar to that used for applying animal
manures, but more sophisticated equipment has been
developed with high flotation tires and improved appli-
cation design. Typically, the dewatered sludge will be
surface-applied and then incorporated by plowing or
another form of tillage. Incorporation, however, is not
used when dewatered sludge is applied to growing for-
ages or to minimum- or no-till land. Sewage sludge
application methods, some of which can be used to
meet Part 503 vector attraction reduction requirements
(i.e., incorporation and injection), are discussed in
greater detail in Chapter 14.
A number of agricultural land application programs using
private farmland have found that soil compaction is an
important concern of farmers (Jacobs et al., 1993).
Therefore, care should be taken to manage the applica-
tion equipment and methods (e.g., use wide-flotation
tires, deep till the staging area following application) to
prevent soil compaction (Jacobs et al., 1993).
66
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Table 7-2. General Guide to Months Available for Sewage Sludge Application for Different Crops in North Central States3
Small Grains'3
Cotton0
Month
Corn
Soybeans
Forages
Winter
Spring
January
February
March
April
May
June
July
August
September
October
November
December
Se
S
S/l
S/l
P, S/l
c
c
c
c
H, S/l
S/l
S
S
S
S/l
S/l
P, S/l
P, S/l
c
c
H, S/l
S/l
S/l
S
S/l
S/l
S/l
P, S/l
c
c
c
c
c
S/l
S/l
S/l
S
S
S
c
c
H, S
H, S
H, S
S
H, S
S
S
C
C
c
c
c
c
H, S/l
S/l
S/l
P, S/l
C
C
S
S
S/l
P, S/l
c
c
H, S/l
S/l
S/l
S/l
S/l
S
Application may not be allowed due to frozen, flooded, or snow-covered soils.
b Wheat, barley, oats, or rye.
c Cotton, only grown south of southern Missouri.
d Established legumes (alfalfa, clover, trefoil, etc.), grass (orchard grass, timothy, brome, reed canary grass, etc.), or legume-grass mixture.
e S = surface application
S/l = surface/incorporation application
C = growing crop present; application would damage crop
P = crop planted; land not available until after harvest
H = after crop harvested, land is available again; for forages (e.g., legumes and grass), availability is limited and application must be light
so regrowth is not suffocated
On arid rangelands, it is important to minimize the dis-
turbance of the soil surface and existing perennial plant
cover. Examples of sewage sludge application to ran-
geland are shown in Table 7-1. Carlile et al. describe the
following application method as one that can be used for
arid rangelands:1
• Shred brush species with an agricultural shredder at a
height that does not disturb underlying grass vegetation.
• Apply the sewage sludge uniformly over the soil surface
with a tractor-drawn agricultural manure spreader.
• Pass over the land with a range dyker and roller to
make small pits and slits in the soil without signifi-
cantly disturbing the grass cover.
7.3.2 Scheduling
The timing of sewage sludge land applications must be
scheduled around the tillage, planting, and harvesting
operations for the crops grown and also can be influ-
enced by crop, climate, and soil properties. Sewage
sludge cannot be applied during periods of inclement
weather. Table 7-2 presents a general guide regarding
when surface and subsurface applications of sludge are
possible for crops in the North Central States. Local
land-grant universities, extension personnel, or others
Carlile, B.L., R.E. Sosebee, B.B. Wester, and R. Zartman. Beneficial use
of biosolids on arid and semi-arid rangeland. Draft report.
with agronomic expertise can provide similar information
for each state or locality.
Under the Part 503 regulation, application of sewage
sludge to agricultural land that is flooded, frozen, or
snow-covered is not prohibited, but the applier must
ensure that no sludge enters wetlands or surface waters
(except as allowed in a Clean Water Act Section 402 or
404 permit). Soil moisture is a major consideration af-
fecting the timing of sludge application. Traffic on wet
soils during or immediately following heavy rainfalls may
result in compaction and may leave deep ruts in the soil,
making crop production difficult and reducing crop
yields. Muddy soils also make vehicle operation difficult
and can create public nuisances by carrying mud out of
the field and onto roadways.
Split applications of sewage sludge may be required for
rates of liquid sludge in excess of 4 to 7 t/ha (2 to 3 dry
T/ac), depending on the percent solids content. Split
application involves more than one application, each at
a relatively low rate, to attain a higher total rate, when
the soil cannot receive the volume of the higher rate at
one time. For example, if a sludge contains 4 percent
solids, the volume of sludge applied at a rate of 11 t/ha
(5 dry T/ac) is approximately 114,000 L/ha (30,000
gal/ac, or about 1.1 acre inch [ac-in]). Application rates
much above 0.3 ac-in at one time will likely result in
runoff or ponding, depending on soil conditions (e.g.,
infiltration rate, water-holding capacity) and slopes.
67
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Thus, if rates such as 1.1 ac-in are desired, three or four
separate applications will probably be needed.
Subsurface injection will minimize runoff from all soils
and can be used on greater slopes. Injection application
rates in one pass, however, are not much greater than
rates with surface application. Injection should be made
perpendicular to slopes to avoid having liquid sludge run
downhill along the injection slits and pond at the bottom
of the slopes. As with surface application, the drier the
soil, the more liquid it will be able to absorb, thereby
minimizing any movement downslope.
7.3.3 Storage
Storage facilities are required to hold sewage sludge
during periods of inclement weather, equipment break-
down, frozen or snow-covered ground, or when land is
unavailable due to growth of a crop. Liquid sewage
sludge can be stored in digesters, tanks, lagoons, or
drying beds; dewatered sewage sludge can be stock-
piled. Volume requirements will depend on individual
systems and climate and can be estimated from the
following data:
• Sewage sludge volume and physical characteristics
• Climatic data
• Cropping data
Chapter 14 contains additional information on evaluat-
ing sludge storage needs.
Some states specify climatic restrictions when sewage
sludge applications are prohibited (e.g., on days when
more than 2.5 mm [0.1 in.] of rainfall occurs). For a
specific site, the average number of days in each month
with these or other weather conditions can be obtained
from the National Climatic Center, NOAA, Asheville,
North Carolina 28801, or from local sources.
Except for forages, sewage sludge application to crop-
land usually is limited to those months of the year when
a crop is not present. The application schedule shown
in Table 7-2 is a general guide for common crops in the
North Central States; similar information can be ob-
tained for other states, as discussed in Section 7.3.2.
The availability of sites used to grow several different
crops will help facilitate the application of sewage sludge
throughout the year. For example, a number of fields
containing forages, corn, and winter wheat would allow
sludge application during nearly all months of the year.
7.4 Determining Sewage Sludge
Application Rates for
Agricultural Sites
Sewage sludge application rates are calculated from
data on sludge composition, soil test information, N and
P fertilizer needs of the crop grown, and concentrations
of trace elements. In essence, this approach views sew-
age sludge as a substitute for conventional N or P
fertilizers in crop production. The number of years that
sewage sludge application may be limited, based on
Part 503 cumulative pollutant loading rate limits for met-
als, is discussed below in Section 7.4.4.3.
The general approach for determining sewage sludge
application rates on agricultural cropland can be sum-
marized as follows:
• Nutrient requirements for the crop selected are based
on yield level and soil test data. If sewage sludge has
been applied in previous years, fertilizer recommen-
dations are corrected for carry-over of nutrients
added by previous sludge additions.
• Annual sewage sludge application rates are calcu-
lated based on N crop needs, P crop needs, and Part
503 annual pollutant loading rate limits, where appli-
cable (bagged sludge).
• Supplemental fertilizer is determined from N, P, and
K needed by the crop and amounts of N, P, and K
provided by sewage sludge application.
• Sewage sludge applications are terminated when a Part
503 cumulative pollutant loading rate limit is reached if
applicable (see Section 7.4.4.3 and Chapter 3).
The majority of sewage sludge contains roughly equal
amounts of total N and P, while crop requirements for N
are generally two to five times greater than those for P.
A conservative approach for determining annual sewage
sludge application rates would involve applying sewage
sludge to meet the P rather than N needs of the crop.
Some states require this approach, particularly when
soil fertility test levels for P are high. With this approach,
farmers would need to supplement sludge N additions
with N fertilizer to achieve the expected crop yield.
7.4.1 Part 503 Agronomic Rate for N and
Pollutant Limits for Metals
The Part 503 rule requires that sewage sludge be land
applied at a rate that is equal to or less than the agro-
nomic rate for N at the application site (i.e., the rate that
will provide the amount of N needed by the crop or
vegetation while minimizing the amount of N that passes
through the root zone and enters the ground water).
Additional Part 503 requirements include:
• Sewage sludge cannot be land applied unless the
trace element (metal) concentrations in the sludge
are below the Part 503 ceiling concentrations.
• The sewage sludge must meet either (1) the pollutant
concentration limits specified in Table 3 of Part 503 or
(2) the Part 503 cumulative pollutant loading rate
(CPLR) limits for bulk sewage sludge or the annual
pollutant loading rate (APLR) limits for bagged sewage
68
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sludge (see Chapter 3). If the sewage sludge meets
the pollutant concentration limits or APLR limits, Part
503 does not require metal loadings to be tracked.
• The sewage sludge must also meet required Part 503
pathogen reduction alternatives and vector attraction
reduction options (see Chapter 3).
Generally, the agronomic rate is the limiting factor re-
garding application rates for sewage sludge rather than
Part 503 pollutant limits. Only when a CPLR limit is
being met and the cumulative loading rate at a site is
approaching the CPLR limit will the Part 503 pollutant
limits become the limiting factor for the sewage sludge
application rate. Section 7.4.4.3 discusses how to cal-
culate sewage sludge application rates based on the
CPLRs. Because the Part 503 rule requires that the
maximum annual application rates for bagged sewage
sludge, based on APLRs, be clearly marked on each
bag, calculation of the APLR is not covered here.
The general approach for calculating sewage sludge
application rates in this manual requires developing as
accurate a mass balance for N in the sewage sludge
and soil-crop system as possible. Equations required for
calculating a N mass balance are relatively simple;
choosing reasonable input values for calculations, how-
ever, is more challenging. For initial calculations, "typi-
cal" and "suggested" values for all necessary parameters
are provided in tables throughout the manual. Site-specific
data or the best judgement of individuals familiar with the
N dynamics of the soil-crop system at the site should
always be used in preference to "typical" values. Particu-
larly for large-scale projects, laboratory mineralization
studies should be considered (see Chapter 13), using
samples of the actual sewage sludge to be applied and
soil materials from the site, because application rate cal-
culations are quite sensitive to the assumed annual N
mineralization percentage used.
7.4.2 Crop Selection and Nutrient
Requirements
The crops grown in an area will influence the scheduling
and methods of sewage sludge application. Utilizing the
cropping systems already present will usually be advan-
tageous, since these crops have evolved because of
local soil, climatic, and economic conditions. Since sew-
age sludge applications typically are limited by the N
requirements of the crop, high N-use crops, such as
forages, corn, and soybeans, will minimize the amount
of land needed and the costs associated with sludge
transportation and application. However, applying
sludge to meet N needs of crops will add excess P, and
eventually rates may need to be reduced to manage
sludge P additions. Therefore, not only is it good prac-
tice to use fields with a mixture of crops, but the prudent
manager of a land application program will continue to
identify additional land areas that can be held in reserve.
Fertilizer recommendations for crops are based on the
nutrients needed to achieve the desired yield of the crop
to be grown and the capacity of the soil to provide the
recommended plant-available nutrients. The amounts of
fertilizer N, P, and K required to attain a given crop yield
have been determined experimentally for numerous
soils in each region of the United States. Crop response
to fertilizer nutrients added has been related to soil test
levels for P, K, Mg, and several of the essential trace
elements (Zn, Cu, Fe, Mn). Accurate measurement of
plant-available N in soil is difficult and also dependent
on climate. As a result, fertilizer N recommendations for
a particular locality are usually developed using a com-
bination of (1) guidelines developed by State Agricultural
Experiment Stations and the Cooperative Extension
Service, based on historical experience with crop yields
on different soil types using different management prac-
tices; (2) soil test data; and (3) estimates of residual N
carryover from previous applications of sewage sludge,
animal manures, or nitrogen-fixing crops, such as alfalfa
and soybeans.
As an illustration of the general approach used to deter-
mine nutrient needs, typical relationships between yield
level, nitrogen required, soil test levels for plant-avail-
able P and K, and fertilizer requirements for P and K are
shown in Tables 7-3 through 7-6 for various crops in the
Midwest. The amounts of supplemental P and K needed
by crops increase as the yield level increases for a fixed
range of existing plant-available P and K in the soil.
Conversely, fertilizer needs decrease at a specific yield
level as soil test levels for P and K increase.
Data such as that presented in Table 7-7 can be used
to estimate the amount of plant-available N that will be
mineralized from sludge organic N applied initially and
from organic N estimated to be remaining from previous
sewage sludge applications. These estimates can then
be used to adjust the fertilizer N recommendations for
the crops to be grown. As has been discussed, however,
the amounts of residual organic N from previous sludge
applications that may be mineralized depend on many
factors. Thus, guidance as to how to best estimate these
quantities of mineralizable N, as well as information on
fertilizer recommendations, should be obtained from the
Agricultural Experiment Stations and Extension Service
of land-grant universities.
7.4.3 Calculating Residual N, P, and K
When sewage sludge is applied to soil each year, the N,
P, and K added in previous years that are not taken up
by crops can be partially available during the current
cropping season. Sewage sludge applied at a rate to
meet the N needs of a crop typically will result in in-
creased soil P levels. Application of sewage sludge
containing high K levels could increase soil K, although
69
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Table 7-3. Representative
Fertilizer Recommendations for Corn and Grain Sorghum in the
Midwest
Fertilizer P (P2Os) and K (foO) Recommended for Soil
Yield
(Metric tons/ha)
6.7-7.4
7.4-8.4
8.4-10.1
10.1-11.8
11.8-13.4
Nitrogen To
Be Applied
(kg/ha)
134
157
190
224
258
Fertilizer
P (P205):
K (K20):
P (P205):
K (K20):
P (P205):
K (K20):
P (P205):
K (K20):
P (P205):
K (K20):
Very Low
49 (113)
93 (112)
54 (1 23)
112 (135)
59 (1 36)
1 40 (1 69)
64 (1 46)
1 67 (201 )
74 (1 69)
186(224)
Low
(kg/ha)
35 (80)
65 (78)
39 (90)
84 (101)
45 (103)
112(135)
49 (113)
130 (157)
59 (136)
Medium
25 (56)
47 (57)
29 (67)
56 (67)
29 (67)
65 (78)
35 (80)
84 (101)
39 (90)
149(179) 112(135)
High
1 5 (33)
28 (34)
1 5 (33)
28 (34)
20 (46)
37 (45)
25 (56)
56 (67)
25 (56)
74 (89)
Fertility* *
Very High
0
0
0
0
4(10)
0
4(10)
0
4(10)
0
* Soil fertility test levels are as follows:
Soil Test
Very low
Low
Medium
High
Very high
f Amounts of P2O5 and K2O
kg/P/ha
0 to 11
1 2 to 22
23 to 33
34 to 77
78+
are shown in
parentheses.
kg/K/ha
0 to 88
89 to 165
166 to 230
231 to 330
331 +
1 kg/ha of fertilizer = 0.89 Ib/ac
1 metric ton/ha of crop yield = 15.3 bu/ac
Table 7-4. Representative
Yield
(Metric tons/ha)
2.0-2.7
2.7-3.4
3.4-4.0
4.0-4.7
>4.7
Fertilizer Recommendations for Soybeans in
Nitrogen To
Be Applied
(kg/ha)
157
196
235
274
336
Fertilizer
P (P205):
K (K2O):
P (P205):
K (K20):
P (P205):
K (K2O):
P (P205):
K (K20):
P (P205):
K (K2O):
Fertilizer
Very Low
29 (67)
99 (119)
39 (90)
112(135)
49(113)
140 (169)
59 (1 36)
167(201)
59 (1 36)
186 (224)
the Midwest
P (P2Os) and K (faO) Recommended for Soil Fertility* t
Low
(kg/ha)
25 (56)
74 (84)
35 (80)
84(101)
84(101)
112 (135)
49 (113)
1 40 (1 69)
49 (113)
158 (190)
Medium
20 (46)
47 (57)
25 (56)
56 (67)
35 (80)
84 (101)
39 (90)
112(135)
39 (90)
121 (146)
High
1 5 (33)
37 (45)
1 5 (33)
56 (67)
20 (46)
56 (67)
25 (56)
74 (89)
25 (56)
74 (89)
Very High
0
0
0
0
0
0
10 (23)
0
10 (23)
19 (23)
* See Table 7-3 for definition of soil fertility test levels.
f Amounts of P2O5 and K2O shown in parentheses.
1 kg/ha of fertilizer = 0.89 Ib/ac
1 metric ton/ha of crop yield = 15.3 bu/ac.
70
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Table 7-5. Representative Fertilizer Recommendations for Small Grains in the Midwest
Fertilizer P (P2Os) and K (faO) Recommended for Soil Fertility*t
Yield
(Metric tons/ha)
Nitrogen To
Be Applied
(kg/ha)
Fertilizer
Very Low
Low
Medium
High
Very High
(kg/ha)
WR:1. 9-2.8*
WR:2.8-3.4
WR:3.4-4.0
WR:4.0-4.6
WR:>4.6
62
73
84
95
106
P (P.O.):
P (P.O.):
P (P.O.):
P (P.O.):
P (P.O.):
45 (1 03)
59 (1 36)
59 (1 36)
69 (1 59)
69 (1 59)
29 (67)
45 (103)
45 (103)
54(123)
54(123)
15(33)
29 (67)
29 (67)
45(103)
45(103)
1 0 (23)
1 5 (33)
1 5 (33)
29 (67)
29 (67)
1 0 (23)
10 (23)
10 (23)
10(23)
10(23)
* See Table 7-3 for definition of soil fertility test levels.
f Amounts of P2O5 and K2O are shown in parentheses.
# WR = Wheat and Rye.
1 kg/ha of fertilizer = 0.89 Ib/ac.
1 metric ton/ha of crop yield = 14.3 bu/ac for wheat and rye.
Table 7-6. Representative Fertilizer Recommendations for Forages in the Midwest
Fertilizer P (P2Os) and K (foO) Recommended for Soil Fertility* t
Yield
(Metric tons/ha)
< 1.8
2.2-2.7
>2.7
Nitrogen To
Be Applied
(kg/ha)
112
224
390
Fertilizer
P (P.O.):
K (KO):
P (P.O.):
K (KO):
P (P.O.):
K (KO):
Very Low
49 (113)
224 (270)
59 (1 36)
336 (405)
69 (1 59)
448 (540)
Low
(kg/ha)
39 (90)
1 86 (224)
49 (113)
280 (337)
59(136)
392 (472)
Medium
25 (56)
140 (169)
35 (80)
224 (270)
45 (103)
336 (405)
High
15 (33)
74 (89)
25 (56)
1 68 (202)
35 (80)
280 (337)
Very High
10 (23)
0
20 (46)
112(135)
25 (56)
224 (270)
* See Table 7-3 for definition of soil fertility test levels.
f Amounts of P2O5 and K2O are shown in parentheses.
1 kg/ha - 0.89 Ib/ac
1 mt/ha - 0.45 T/ac
71
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Table 7-7. Estimated Mineralization Rates (Kmin) for Different Sewage Sludges (Adapted From Sommers et al, 1981)
Fraction (Kmin)* of Organic N Mineralized From the Following Sludges:
Time After Sewage Sludge
Application (Years)
0-1
1-2
2-3
3-4
Unstabilized Primary
and Waste
0.40
0.20
0.10
0.05
Aerobically
Digested
0.30
0.15
0.08
0.04
Anaerobically
Digested
0.20
0.10
0.05
-
Composted
0.10
0.05
_t
-
* Fraction of the sludge organic N (Org-N) initially applied, or remaining in the soil, that will be mineralized during the time interval shown. K,™
values are provided as examples only and may be quite different for different sewage sludges, soils, and climates. Therefore, site-specific
data, or the best judgement of individuals familiar with N dynamics in the soil-plant system, should always be used in preference to these
suggested Kmin values.
t
Once the mineralization rate becomes less than 3% (i.e., 0.03), no net gain of PAN above that normally obtained from the mineralization of
soil organic matter is expected. Therefore, additional credits for residual sludge N do not need to be calculated.
agronomic rates (for N) of sewage sludge usually will
add K at levels less than crop needs.
The contribution of residual N carryover to plant-avail-
able N can be significant when sewage sludge is
applied each year. Although the largest percentage of
mineralizable organic N is converted to inorganic N
during the year that the sludge is applied, the contin-
ued decomposition of organic N in succeeding years
can provide some additional plant-available N for crop
growth. The amount of N mineralized in sludge-
treated soils is dependent on the type of sludge treat-
ment processes used, the ratio of inorganic to organic
N in the sludge, and the amount of organic N applied
in previous years.
The approach proposed for evaluating residual N, P, and
K from previous sewage sludge applications is as follows:
• P and K—Assume that 50 percent of the P and 100
percent of the K applied are available for plant uptake
in the year of application. These quantities of P and
K can be credited against fertilizer recommendations.
Any P and K in excess of plant needs will contribute
to soil fertility levels that can be regularly monitored
and taken into account when determining fertilizer
recommendations in succeeding years.
• N—Plant-available N (PAN) that may be mineralized
from residual sludge organic N can sometimes be
estimated by using soil tests (see Chapter 6). How-
ever, estimating PAN by using mineralization factors
recommended by land-grant universities or state
regulatory agencies is more common. The largest
portion of organic N in sewage sludge is converted
to inorganic N during the first year after application
to the soil. After the first year, the amount of N min-
eralization decreases each year until it stabilizes at
about 3 percent, a rate often observed for stable
organic N fractions in soils. Once the 3 percent level
has been reached, any additional quantities of PAN
will not be significant enough to credit against the
fertilizer N recommendation.
Table 7-7 suggests a decay sequence where the
amount of N mineralized decreases by about 50 per-
cent each year until the 3 percent rate is reached.
Using anaerobically digested sewage sludge as an
example, if 20 percent of the organic N was miner-
alized during the first year, the amounts released in
years 2 and 3 would be 10 and 5 percent, respec-
tively, of the organic N remaining (see Table 7-7).
After year 3, the mineralization rate decreases to the
background rate for soil organic matter, so no addi-
tional credit for residual sludge organic N is calcu-
lated. This decay sequence may or may not be the
most appropriate one to use for your state or location,
but it will be used to illustrate how mineralizable N can
be calculated to estimate PAN credits.
7.4.4 Calculation of Annual Application Rates
Recommended annual rates of sewage sludge applica-
tion on cropland are based on the N or P requirements
of the crop grown, the N and P levels in the sludge, and
the metal concentrations in the sludge for which pollut-
ant limits have been set in the Part 503 rule. As dis-
cussed in the previous section, the fertilizer N
recommendation for the crop and yield level expected
should be corrected for plant-available N mineralized
from prior sludge additions. The basic approach for
determining annual application rates of sewage sludge
involves using data on sewage sludge composition to
calculate maximum potential application rates based on
(1) crop N requirements, (2) crop P requirements, and
(3) Part 503 pollutant limits. In most cases, the actual
application rate will be selected from the following two
possibilities:
• The annual agronomic rate can be utilized to provide
recommended N needs until the Part 503 CPLR limits
for metals are reached, unless the sewage sludge
meets the pollutant concentration limits in Table 3 of
Part 503, in which case cumulative metal loadings do
not need to be tracked. (In some cases, this approach
may result in the accumulation of excess P in the soil,
72
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which can increase the potential for P entering
streams and lakes through surface erosion).
• In some states, the annual rate may be limited to a
rate where sludge P is equal to fertilizer P recom-
mendations or the P removed by the crop. Nitrogen
may be applied at less than the crop N need. This P
rate could be followed as long as it did not exceed
the agronomic N rate or any Section 503 pollutant
loading limits for metals.
Another possibility is that the metals loadings at the site
are approaching a Part 503 CPLR limit, which may result
in an application rate that is less than the crop's N or P
needs (i.e., sewage sludges that do not meet the Part
503 pollutant concentration limits for metals). Reaching
a CPLR limit terminates CPLR sewage sludge applica-
tion to land, in which case other options, such as incin-
eration or surface disposal, are likely to be more feasible.
Currently, however, a majority of sewage sludge in the
United States can meet Part 503's pollutant concentration
limits. Thus, the nutrient requirements of a crop will likely
be the limiting factor rather than Part 503 pollutant limits.
The following section summarizes the basic calculations
used to determine sewage sludge application rates
based on N (Section 7.4.4.1) and P (Section 7.4.4.2),
and the estimated project life based on CPLR limits
(Section 7.4.4.3). The design example (Section 7.5)
provides additional illustrations of these calculations.
7.4.4.1 Calculation Based on Nitrogen
As discussed previously, not all the N in sewage sludge
is immediately available to plants, since some is present
as organic N (Org-N), i.e., in microbial cell tissue and
other organic compounds. Organic N must be decom-
posed into mineral, or inorganic forms, such as NH4-N
and NO3-N, before it can be used by plants. Therefore,
the availability of Org-N for plants depends on the mi-
crobial breakdown of organic materials (e.g., sewage
sludge, animal manure, crop residues, soil organic mat-
ter, etc.) in soils.
The proportion of sludge Org-N that is mineralized in a
soil depends on various factors which influence immo-
bilization and mineralization of organic forms of N
(Bartholomew, 1965; Harmsen and van Schreven, 1955;
Smith and Peterson, 1982; Sommers and Giordano,
1984). Schemes for estimating the amount of miner-
alizable N from organic fertilizers, like animal manure
and sewage sludge, have been suggested (Pratt et al.,
1973; Powers, 1975; Smith and Peterson, 1982; USDA,
1979; USEPA, 1975, 1983).
Estimates of mineralizable N using decay (decomposi-
tion) series are not precise, however, since the actual N
availability will depend on organic N composition, de-
gree of treatment or stabilization of the sewage sludge
before land application, climate, soil conditions, and other
factors. Another approach to predicting N availability is
to model (mathematically) the transformations of N in
the soil. However, modeling has not yet been found to
be accurate enough to give more than a general esti-
mate of N availability (Schepers and Fox, 1989). Never-
theless, management strategies must attempt to
balance the addition of plant-available N, provided by
land application of organic materials like sewage sludge,
with the needs of the crop. Otherwise, excess NOa-N
can be leached into groundwater by precipitation or poor
management of irrigation water (Keeney, 1989).
The plant-available N, or PAN, provided by sewage
sludge is influenced by several factors. Initially, the
quantity of total N in the sludge and the concentrations
of NO3-N, NH4-N and Org-N (which together make up
the total N) must be determined. Commonly, the concen-
tration of Org-N is estimated by subtracting the concen-
tration of NO3-N and NH4-N from the total N, i.e.,
Org-N = total N - (NO3-N + NH4-N). The NH4-N and
NO3-N added by sludge is considered to be as available
for plants to utilize as NH4-N and NO3-N added by fertilizer
salts or other sources of these mineral forms of N.
The availability of sewage sludge Org-N will depend on
the type of treatment or stabilization the sludge received.
Anaerobically digested sludge normally will have high
levels of NH4-N and very little NO3-N, while aerobically
digested sludge will have higher levels of NOa-N by
comparison. Composting and anaerobic digestion ac-
complishes greater stabilization of organic carbon com-
pounds than aerobic digestion or waste activation. The
greater the stabilization, the slower the rate of minerali-
zation of carbon compounds (containing Org-N from the
sewage sludge) and the lower the amounts of Org-N
released for plant uptake.
Differences between these various types of sewage
sludges can be seen in Table 7-7 which shows average
mineralization rates for the first through fourth year fol-
lowing a sludge application (Sommers et al., 1981).
These values, however, are averages only and can vary
significantly due to differences in the characteristics of
the sewage sludge, soil, and climate (i.e., temperature
and rainfall). For example, assuming adequate moisture
is available for microbial decomposition, increases in
temperature will increase the activity of microorganisms.
Therefore, mineralization rates are typically higher in the
summer months than in the winter months and higher in
the southern U.S. than in the northern states. Because
of these differences, calculating the agronomic rate
should be done on a site-specific basis. Using minerali-
zation factors recommended by state regulatory agen-
cies and land-grant universities that are based on
decomposition or N mineralization studies, computer
simulations that estimate decomposition, or docu-
mented field experience is advised.
73
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The amount of PAN also will be affected by the amount
of NH4-N lost by volatilization of ammonia (NH3). Ammo-
nia volatilization losses, when animal manure orsewage
sludge is applied to land, have long been recognized
(Adriano et al., 1974; Beauchamp et al., 1978, 1982;
Brunke et al., 1988; Christensen, 1986; Db'hler and
Wiechmann, 1988; Hall and Ryden, 1986; Hoff et al.,
1981; Lauer et al., 1976; Rank et al., 1988; Reddy et al.,
1979; Terman, 1979; Vallis et al., 1982). Accurately es-
timating the extent of this loss is difficult, however, given
the variability in weather conditions that largely dictate
how fast volatilization will occur.
In addition to weather conditions, the method of sewage
sludge application, the length of time sewage sludge
remains on the soil surface prior to incorporation, and
the pH (e.g., lime content) of the sewage sludge also will
influence the potential for volatilization losses. High pH
in sewage sludge or soil will encourage the conversion
of NH4-N to NH3, resulting in a N loss to the atmosphere.
The longer the sludge remains on the soil surface and
is subjected to drying conditions, the greater the risk of
NH3 volatilization losses.
With injection of liquid sewage sludge, little NH3 should
be lost to volatilization, except possibly on coarsely
textured (sandy) soils. Volatilization losses, however,
should be considered for surface-applied liquid sewage
sludge that is later incorporated and for surface-applied
dewatered sewage sludge that is later incorporated or
remains on the surface. This N loss needs to be consid-
ered, or the amount of PAN reported to the farmer as
being applied will be overestimated.
Volatilization losses of NH4-N from animal manure also
are of interest in many states, and guidance often is
provided by state land-grant universities; thus, applica-
tors of sewage sludge may want to seek similar guid-
ance to estimate loss of NH4-N as NH3 during sewage
sludge application. In addition, several states (e.g., Vir-
ginia, Washington) have developed specific guidance on
NH3 volatilization from sewage sludge that takes into
account such factors as lime content of the sewage
sludge and the length of time sewage sludge remains
on the soil surface before it is incorporated.
For these reasons, Table 7-8 can serve as guidance for
estimating NH4-N losses as NH3. As indicated earlier,
these volatilization factors may not be the most appro-
priate for a specific site, so values should be obtained
from state regulatory agencies or state land-grant uni-
versities that are more site-specific for a particular location.
The inability to accurately estimate volatilization losses,
combined with the difficulty of estimating the amount of
mineralizable N, means that regulators need to remain
flexible regarding the methods used to estimate the
amount of PAN per dry ton of sewage sludge.
Table 7-8. Volatilization Losses of NH4-N as NH3
Sewage Sludge Type and
Application Method
NH3 Volatilization
Factor, Kvo,
Liquid and surface applied
Liquid and injected into the soil
Dewatered and surface applied
0.50
1.0
0.50
With these factors in mind, a number of steps can be used
to determine the agronomic rate (i.e., based on PAN).
These steps are summarized below and also are shown
on Worksheets 1 and 2 (see Figures 7-1 and 7-2):
1. Determine the fertilizer N recommendation for the
crop and yield level anticipated on the soil that is to
receive the sewage sludge application. (Since
legume crops can fix their own N, they usually will
not have a N fertilizer recommendation. Legume
crops, however, will utilize N that is applied as
fertilizer, manure, or sewage sludge, so N crop
removal values can be used to estimate the N
requirement for these crops.)
2. Subtract anticipated N credits from the recommended
fertilizer N rate, i.e., for other sources of N such as the
following:
a. Residual N left by a previous legume crop (leg-
umes have the ability to fix N from the air, and
varying levels of N will be left in the soil when
legumes are replaced by another crop; land-grant
universities can provide appropriate credits that
should be used for a particular site).
b. Any N that has already been applied or will be
applied during the growth of the crop by fertilizer,
manure, or other sources that will be readily avail-
able for plants to use.
c. Any N that is anticipated to be added by irriga-
tion water that will be applied during the growth
of the crop.
d. Any residual Org-N remaining from previous sew-
age sludge applications. As previously discussed,
Table 7-7 lists average mineralization rates, but
more sewage sludge-specific and site-specific infor-
mation should be used when available. Experience
over time has shown that when agronomic rates
of sewage sludge are used, no additional PAN
above that normally obtained from soil organic
matter turnover is expected after 3-4 years. There-
fore, calculating PAN credits for a sludge applica-
tion beyond the third year is not recommended,
since these quantities are negligible. The chart in
Worksheet 1 and the mineralization factors in Ta-
ble 7-7 can be used to estimate the PAN for years
2 and 3. An example calculation is included in
Worksheet 1.
74
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Worksheet 1
Calculations for Determining PAN Mineralized From
Residual Organic N Applied as Sewage Sludge in Previous Years
Residual N from previously-applied sewage sludge that will be mineralized and released as plant-available
N (PAN) must be accounted for as part of the overall budget for PAN, when determining the agronomic
N rate for sewage sludge (i.e., Worksheet 2). This residual N credit can be estimated for some sites using
soil nitrate tests, but more commonly the PAN credit is estimated by multiplying a mineralization factor
(K^) times the amount of sludge organic N (Org-N) still remaining in the soil one and two years after
sludge has been applied.
Instructions: Complete a separate chart for each year that sewage sludge was previously-applied. Studies
and experience have shown that any residual sludge Org-N remaining 2-3 years after application
will not contribute significantly to PAN normally mineralized from soil organic matter
decomposition. Therefore, calculating PAN credits beyond the third year is usually not necessary.
To determine total mineralized Org-N released as PAN, sum the values under Mineralized Org-N
(Column D) for the "Growing Season Year" for which you are planning a new sludge application
to estimate the residual N credit for sludge applications the previous two years.
A. Year of
Growing Season1
0-1 (sludge
applied)
1-2 (one year
later)
2-3 (two years
later)
B. Starting Org-N2
(Ib/acre)
C. Mineralization
Rate3 (K,™)
D. Mineralized
Org-N4 or PAN
(Ib/acre)
E. Org-N
Remaining5
(Ib/acre)
1 Begin with the growing season (i.e., year the crop will be grown) for which sewage sludge was applied
and continue two more years (i.e., two more growing seasons).
2 For the first year, this equals the percent Org-N in the sludge times the rate of application. For years
1-2 and 2-3, this quantity equals the amount of Org-N remaining from the previous year (i.e., column
E).
3 The mineralization rate is the fraction of sludge Org-N expected to be released as PAN for the year
being calculated. Example mineralization rates can be found in Table 7-7.
4 Multiply column C times column B and round to the nearest whole pound.
5 Subtract column D from column B and round to the nearest whole pound.
Figure 7-1. Determining mineralized PAN from previous sludge applications.
75
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Worksheet 1 (continued)
Example
Assume that anaerobically digested sewage sludge with 2.5% Org-N (dry weight basis) was applied at a
rate of 3 ton/acre for the 1996 growing season. For the 1997 growing season, 2 ton/acre of a sludge
containing 3.0% Org-N was applied to the same site. For the 1998 growing season, calculate the amount
of PAN that will be mineralized from the sludge Org-N applied in the previous 2 years.
In 1996, the sludge Org-N applied = 2.5 Ib Org-N x 3 ton sludge x 2000 Ib sludge = 150 Ib Org-N/acre
100 Ib sludge acre ton sludge
In 1997, the sludge Org-N applied = 3.0 Ib Org-N x 2 ton sludge x 2000 Ib sludge = 120 Ib Org-N/acre
100 Ib sludge acre ton sludge
Use Worksheet 1 to calculate the PAN released during the 1998 growing season from the sludge applied
in 1996 and 1997.
A. Year of
Growing Season
B. Starting Org-
N (Ib/acre)
C. Mineralization
Rate (K^)
D. Mineralized
Org-N (Ib/acre)
E. Org-N
Remaining
(Ib/acre)
1996 Sludge Application
0-1 (1996
Application)
1-2 (1997)
2-3 (1998)
150
120
108
0.20
0.10
0.05
30
12
5
120
108
103
1997 Sludge Application
0-1 (1997
Application)
1-2 (1998)
2-3 (1999)
120
96
86
0.20
0.10
0.05
24
10
4
96
86
82
To determine the total amount of PAN mineralized in 1998 from sludge applied in 1996 and 1997, add the
Mineralized Org-N (or PAN) value in the 1998 row under column D for each year's chart (i.e., 5 + 10 =
15 Ib PAN/acre). Therefore, the total PAN, or mineralized Org-N, from previous sludge applications
equals 15 Ib/acre.
Figure 7-1. Determining mineralized PAN from previous sludge applications (continued).
76
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Worksheet 2
Nitrogen Budget Sheet for Determining the Agronomic N Rate
for Sewage Sludge Applications
Symbols and Abbreviations Used
Org-N = Organic N content of the sewage sludge obtained from analytical testing and determined by
subtracting (NO3-N + NH4-N) from total N, usually given in percent (%); the resulting
concentration should be converted to Ib/ton (dry weight basis).
NH4-N = Ammonium N content of the sewage sludge obtained from analytical testing and usually
given in percent (%); convert to Ib/ton (d,w. basis).
NO3-N = Nitrate N content of the sewage sludge obtained from analytical testing and often given in
mg/kg; convert to Ib/ton (d.w. basis).
K^n = Mineralization rate for the sewage sludge expressed as a fraction of the sludge Org-N
expected to be released as PAN for the year being calculated; example mineralization rates for
different sewage sludges can be found in Table 7-7.
Ky,,, = Volatilization factor for estimating the amount of NH4-N remaining after loss to the
atmosphere as ammonia and expressed as a fraction (e.g., if K^ = 1.0, 100% of the NH4-N is
retained and contributes to PAN; if K^ = 0.5, then 0.5 x NH4-N estimates the amount of NH4-N
contributing to PAN).
PAN = Plant-available N, determined by calculating: NO3-N + Kvol(NH4-N) + K^Org-N)
Helpful Conversions
mg/kg x 0.002 = Ib/ton Ib/acrex 1.12 = kg/ha Ib/ton H- 2 = kg/mt
% x 20 = Ib/ton ton/acre x 2.24 = mt/ha (mt = metric ton = 1000 kg)
1. Total N requirement of crop to be grown (obtain information from Cooperative Extension Ib/acre
Service agricultural agents, USDA-Natural Resource Conservation Service, or other
agronomy professionals).
2. Nitrogen provided from other N sources added or mineralized in the soil
a. N from a previous legume crop (legume credit) or green manure crop Ib/acre
b. N from supplemental fertilizers already, or expected to be, added Ib/acre
c. N that will be added by irrigation water Ib/acre
d. Estimate of available N from previous sludge applications (from Worksheet 1) Ib/acre
e. Estimate of available N from a previous manure application (obtain mineralization Ib/acre
factors from land-grant university to calculate similarly as for previous sewage
sludge applications').
f. Soil nitrate test of available N present in soil [this quantity can be substituted Ib/acre
in place of (a + d + e) if lest is conducted properly; do not use this test value if
estimates for a, d and e are used]
Total N available from existing, expected, and planned sources of N (add a+b+c+d+e or b+c+f) Ib/acre
3. Loss of available N by denitrification, immobilization, or NH4+ fixation (check with state regulatory Ib/acre
agency for approval before using this site-specific factor).
4. Calculate the adjusted fertilizer N requirement for the crop to be grown (subtract Total N for (2) Ib/acre
from (1); amount for (3) can be added to this difference, only if (3) is approved for this additional adjustment).
Figure 7-2. Determining agronomic N rate.
77
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Worksheet 2 (continued)
5. Determine the PAN/dry ton for the sludge that will be applied ^^_^^ Ib/ton
[i.e., NOj-N + K,., (NH4-N) + K^. (Org-N) = PAN]
6. Calculate the agronomic N rate of sewage sludge (Divide (4) by (5)) ton/acre
7. Convert the rate of sewage sludge in dry tons/acre into gallons/acre, cubic yards/acre, or wet tons/acre,
since the sludge will be applied to land as a liquid or as a wet cake material.
Figure 7-2. Determining agronomic N rate (continued).
78
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e. Residual organic N remaining from any previous
animal manure application should be estimated.
Various decay schemes are used for manure ap-
plications by land-grant universities, so residual
N released from a previous manure application
can be estimated in a similar manner as for sew-
age sludge applications (i.e., step 2.d).
f. The combined residual N already present in the
soil or expected to be available for crops to use
can sometimes be estimated by the soil nitrate
test (e.g., inorganic N left from previous fertilizer,
manure, sludge, etc. applications; or credits given
for the mineralization of soil organic matter and
legume crop residues). The soil nitrate test can
be used in some states to estimate quantities of
NO3-N that may be present from previous fertilizer
N, manure, and/or sewage sludge applied and/or
from mineralization of N from legume crops and
soil organic matter. But because NO3-N can be
lost by leaching, the soil nitrate test must be used
with care in semi-humid and humid climates.
Therefore, guidance should be obtained from a
land-grant university for the proper credits to use.
Note that if a soil nitrate test is used to estimate
residual N contributions, then estimates for steps
2.a, 2.d, and 2.e should not be included in the
summation done in step 2 on Worksheet 2.
3. Add any anticipated N losses due to denitrification,
immobilization, or chemical fixation of NHJ by
micaceous (i.e., mica-containing) clay minerals (use
only if approved by regulatory agency). Denitri-
fication [i.e., the loss of NO3-N as nitrogen (N2) or
nitrous oxide (N2O) gases] and immobilization (i.e.,
the loss of NO3-N or NH4-N by incorporation into
organic compounds by the soil biology) can occur in
soils. For soils containing hydrous mica clay
minerals, some NHJ may become fixed within the
crystal lattices of these minerals in spaces normally
occupied by K+. If this occurs, NHJ is unavailable for
plant uptake unless mineral weathering occurs to
again release the NHJ.
The source of the NO3-N and NH4-N can be from
fertilizer, manure, etc. as well as sewage sludge
applications. Note that if fertilizer recommendations
are used which account for average losses due to
biological denitrification and immobilization or chemical
fixation of NHJ, a separate credit for these processes
should not be used for this step. Therefore, adding
these anticipated N losses should not be done
unless justification is provided to the permitting
authority and approval is received.
4. Use Worksheet 2 to determine the adjusted fertilizer
N rate by subtracting "total N available from existing,
anticipated, and planned sources" (Worksheet step
2) from "total N requirement of crop" (Worksheet step
1). If a loss of available N by denitrification, immobil-
ization or NHJ fixation is allowed (i.e., approved by
the state regulatory agency), this anticipated loss
can be added to the difference obtained when
subtracting the step 2 total from the step 1 amount
to obtain a final adjusted fertilizer N rate.
5. Determine the PAN/dry ton of sewage sludge for the
first year of application using the following equation:
PAN = N03-N +
where:
i (NH4-N) + Kmin (Org-N)
PAN = plant-available N in Ib/dry ton sewage
sludge
NO3-N = content of nitrate N in sewage sludge
in Ib/dry ton
Kvoi = volatilization factor, or fraction of NhU-N
not lost as NHs gas to the atmosphere
NH4-N = content of ammonium N in sewage
sludge in Ib/dry ton
Kmin = mineralization factor, or fraction of
Org-N converted to PAN
Org-N = content of organic N in sewage sludge
in Ib/dry ton, estimated by Org. N =
total N - (NOs-N + NhU-N)
Example: Assume liquid, aerobically digested
sewage sludge is to be incorporated into the soil
by direct injection (i.e., K^, = 1 .0). The suggested
mineralization rate in Table 7-7 is K^ = 0.30 for
the first year. The chemical analysis of the sludge
shows N03-N = 1,100 mg/kg, NH4-N = 1.1% and
total N = 3.4%, all on a dry weight basis, and
percent dry solids is 4.6%.
a. First convert concentrations to Ib/dry ton:
for N03-N — 1 ,1 00 mg/kg x 0.002 = 2.2, or 2 Ib/ton
(rounded to nearest whole Ib)
for NH4-N — 1 .1% x 20 = 22 Ib/ton
for total N — 3.4% x 20 = 68 Ib/ton
for Org-N — 68 - (2 + 22) = 44 Ib/ton
b. Calculate PAN:
PAN = 2 + 1 .0 (22 Ib/ton) + 0.3 (44 Ib/ton) =
2 + 22 + 13 = 37 Ib/ton
6. Divide the adjusted fertilizer N rate (Ib N/acre from step
4) by the PAN/dry ton sewage sludge (Ib N/ton from
step 5) to obtain the agronomic N rate in dry tons/acre.
Example: Assume the adjusted fertilizer N rate
from step 4 is 130 Ib N/acre and the aerobically
digested sewage sludge from the example in step
79
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5 above is used to provide crop N needs. What is
the agronomic N rate?
Agronomic N rate = 130 Ib N/acre -^ 37 Ib N/ton
= 3.5 dry tons/acre
7. This dry ton/acre rate can be converted to wet
gallons/acre, since this is the form in which the
sewage sludge will be applied:
wet tons/acre = 3.5 dry ton/acre -^ 4.6 dry ton/100
wet ton (i.e., 4.6% solids) = 76 wet ton/acre
This wet tonnage can then be converted to gallons/acre
by the following conversion:
76 wet ton/acre x 2,000 Ib/wet ton x
1 gallon/8.34 Ib = 18,200 gallons/acre
This rate would be equivalent to about 2/3 acre-inch of
liquid (1 acre-inch = 27,150 gal), too much to apply in
one application. Probably 13,000-15,000 gal/acre is a
maximum amount that can normally be applied at one
time using injection.
7.4.4.2 Calculation Based on Phosphorus
The majority of P in sewage sludge is present as inor-
ganic compounds. While mineralization of organic forms
of P occurs during decomposition of sludge organic
matter, inorganic reactions of P are of greater impor-
tance when considering sludge P additions. Because of
the predominance of inorganic P, therefore, the P con-
tained in sewage sludge is considered to be about 50
percent as available for plant uptake as the P normally
applied to soils in commercial fertilizers (e.g., triple su-
perphosphate, diammonium phosphate, etc.). As pre-
viously discussed, the P fertilizer needs of the crop to
be grown are determined from the soil fertility test for
available P and the yield of the crop. The agronomic P
rate of sewage sludge for land application can be deter-
mined by the following equations:
Agronomic P Rate = Preq + Avail. P2Os/dry ton
where:
req
= the P fertilizer recommenda-
tion for the harvested crop, or
the quantity of P removed by
the crop,
Avail. P2Os = 0.5 (total P2Os/dry ton)
Total P2O5/dry ton = %P in sludge x 20 x 2.3*
*2.3 is the factor to convert Ib P to Ib P2Os (the ra-
tio of the atomic weights of P2Os:P, i.e.,142:62).
For nearly all sewage sludge, supplemental N fertiliza-
tion will be needed to optimize crop yields (except for
N-fixing legumes) if application rates are based on a
crop's P needs.
7.4.4.3 Calculation Based on Pollutant
Limitations
The literature pertaining to trace element (metal) addi-
tions to the soil-plant system from sewage sludge ap-
plications is extensive, and several key references can
be a source of more in-depth discussions (Allaway,
1977; Berglund et al., 1984; CAST, 1976, 1980;
Chaney, 1973, 1983a, 1983b, 1984; Chaney and Gior-
dano, 1977; Davis etal., 1983; L'Hermite and Dehandt-
schutter, 1981; Lindsay, 1973; Logan and Chaney,
1983; Melsted, 1973; Page et al., 1987; Ryan and
Chaney, 1993; Sommers and Barbarick, 1986; U.S.
EPA, 1974; Walsh et al., 1976). Potential hazards as-
sociated with trace element additions have mostly per-
tained to their accumulation in soils which may (1) lead
to a plant toxicity condition or (2) result in increased
uptake of trace elements into the food chain.
As discussed in Chapter 3, the pollutant limits estab-
lished in the Part 503 regulation protect human health
and the environment from reasonably anticipated ad-
verse effects of pollutants that may be present in sew-
age sludge.
Because most sewage sludges will likely contain pollut-
ant concentrations that do not exceed the Part 503
"pollutant concentration limits" (see Chapter 3), pollut-
ant loading limits will not be a factor in determining
annual sewage sludge application rates for these sew-
age sludges. For other sewage sludges that have pol-
lutant concentrations that exceed one or more of the
Part 503 "pollutant concentration limits," the Part 503
"cumulative pollutant loading rates" (CPLRs) discussed
in Chapter 3 and shown in Table 7-9 must be met;
CPLRs could eventually be the limiting factor for annual
Table 7-9. Part 503 Cumulative Pollutant Loading Rate
(CLPR) Limits
Loading Limits
Pollutant
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
kg/ha
41
39
3,000a
1,500
300
17
a
420
100
2,800
Ib/acre
37
35
2,700
1,300
270
15
—
380
90
2,500
Chromium limits will most likely be deleted from Part 503. The CPLR
for Mo was deleted from Part 503 effective February 25,
1994. EPA will reconsider this limit at a later date.
80
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sewage sludge applications (rather than the agronomic
rate of application).
For sewage sludge meeting Part 503 CPLRs, two equa-
tions are helpful for managing pollutant loadings to soils.
The first equation can be used to estimate the maximum
total quantity of sewage sludge permitted to be applied
to a soil, based on the CPLR and the pollutant concen-
tration in the sewage sludge being considered:
Maximum sewage sludge allowed (dry tons/acre) =
Ib/acre (CPLR) + 0.002 (ppm pollutant)
where:
ppm pollutant = mg of pollutant per kg of dry sew-
age sludge.
After making this calculation for each of the 10 pollutants
regulated by Part 503, the lowest "total sewage sludge"
value should be used as the maximum quantity of sew-
age sludge allowed to be applied for that particular site.
The design example in Section 7.5 shows how this
equation is used.
A second equation, also illustrated in Section 7.5, can
be used to determine the individual pollutant loading
added by each sewage sludge application rate:
Ib of pollutant/acre = sludge rate (dry tons/acre) x
0.002 (ppm pollutant)
A cumulative record of individual applications is then
kept for each field receiving sewage sludge that is meet-
ing the CPLRs. When the cumulative amount of any one
regulated pollutant reaches its CPLR, no additional
CPLR sewage sludge can be applied.
7.4.5 Calculation of Supplemental N, P, and
K Fertilizer
Once the application rate of sewage sludge has been deter-
mined, the amounts of plant-available N, P, and K added by
the sludge should be calculated and compared to the fertil-
izer recommendation for the crop (and yield level) to be
grown. If the amount of one or more of these three nutrients
provided by the sewage sludge are less than the amount
recommended, then supplemental fertilizers will be needed
to achieve crop yields. Refer to the design example in
Section 7.5 for an illustration of how this is determined.
7.4.6 Use of Computer Models To Assist in
Determining Agronomic Rates
Computer modeling often can be useful for site-specific
evaluation of sewage-sludge-climate-soil-plant N dy-
namics at a particular location, generally with minimal
additional data collection.
Computer models that specifically model N budgets in
sewage sludge and soil-plant systems can provide site-
specific information on soil physical and hydrologic con-
ditions and climatic influences on N transformations.
The Nitrate Leaching and Economic Analysis Package
(NLEAP) developed by Shaffer et al. (1991) allows
monthly and event-by-event approaches throughout the
year to compute water and N budgets. The NLEAP
software is included in the purchase of Managing Nitro-
gen for Groundwater Quality and Farm Profitability
(Follet et al., 1991), which also serves as an excellent
reference for information on parameters required for N
budget calculations. Four regional soil and climatic da-
tabases (Upper Midwest, Southern, Northeastern, and
Western) also are available on disk for use with NLEAP.
These materials can be obtained from:
Soil Science Society of America
Attn: Book Order Department
677 S. Segoe Road
Madison, Wl 53711
608/273-2021; Book $36.00;
Regional Databases $10.00 each.
Current updates of the NLEAP program can be obtained
by sending original diskettes to:
Mary Brodahl
USDA-ARS-GPSR
BoxE
Fort Collins, CO 80522
The computer model DECOMPOSITION (Gilmour and
Clark, 1988) is specifically designed to help predict sew-
age sludge N transformations based on sludge charac-
teristics as well as soil properties and climate (organic
matter content, mean soil temperature, and water poten-
tial). Additional information on this model can be ob-
tained from:
Mark D. Clark
Predictive Modeling
P.O. Box 610
Fayetteville, AR 72702
Finally, the CREAMS (Chemicals, Runoff, and Erosion
from Agricultural Management Systems) and GLEAMS
(Groundwater Loading Effects of Agricultural Manage-
ment Systems) models, developed by the U.S. Depart-
ment of Agriculture (Beasley et al., 1991; Davis et al.,
1990; Knisel, 1980), are other potentially useful models
to assist with site-specific management of sewage
sludge application programs.
81
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7.5 Design Example of Sewage Sludge
Application Rate Calculations
The following detailed design example is for a midwest-
ern city with 20 dry ton/day (18 mt/day) of sewage
sludge requiring land application. The sewage sludge
has undergone anaerobic digestion and has the follow-
ing characteristics:
• Solids - 4.8 percent
• Total N - 3.9 percent
• NH4-N - 1.2 percent
• N03-N - 200 mg/kg
• Total P - 1.9 percent
• Total K - 0.5 percent
• As - 8 mg/kg
• Cd - 10 mg/kg
• Cr - 130 mg/kg
• Cu - 1,700 mg/kg
• Pb - 150 mg/kg
• Hg - 2 mg/kg
• Mo - 14 mg/kg
• Ni - 49 mg/kg
• Se - 15 mg/kg
• Zn - 1,200 mg/kg
Climatological data were collected for the application
area as described in Chapter 5. Sewage sludge appli-
cation will be limited during periods of high rainfall and
high soil moisture conditions because of the potential for
surface runoff and the inability to use sludge application
equipment. In addition, sludge application will not occur
during periods of extended subfreezing temperatures
due to frozen soils, as indicated by Part 503.
For this site, assume that:
• Annual sewage sludge applications cannot exceed the N
requirement for the crop grown, as required by Part 503.
• Soil pH will be maintained at levels recommended by
land-grant universities for the crop to be grown (or
as required by state regulatory agencies).
• If nutrient additions by the sewage sludge application
are not sufficient, supplemental fertilizer nutrients will
be used to optimize crop production.
• Routine soil fertility testing will be done to establish
fertilizer recommendations and lime requirements for
optimum crop growth.
• The sewage treatment plant regularly monitors
chemical composition of the sludge as required by
Part 503 and state regulatory agencies.
• Records are maintained as required by Part 503 and
state regulatory agencies.
Soils in the site area are generally sandy loams. Soil
fertility tests have been completed and soil pH is being
maintained as recommended. Crops grown in the area
include corn, soybeans, oats, wheat, and forages for hay
and pasture. For the 1995 growing season, one half of
the fields receiving sludge will be cropped with wheat
requiring 90 Ib/ac (100 kg/ha) of available N per year,
and one half of the fields will be cropped with corn
requiring 190 Ib/ac (210 kg/ha) of available N per year.
Crop fertilizer requirements were obtained from local
Cooperative Extension Service agents for anticipated yield
levels of 80 bu/ac for wheat and 160 bu/ac for corn grain.
The soil fertility tests indicated that available P levels in
the soil are medium, and that available K levels are low.
N
P205 K20
Crop
Corn
Wheat
Yield (bu/ac)
160
80
(Ih/ar/year)
190 60 140
90
80
125
Assume that this anaerobically-digested sewage sludge
was previously applied to the fields in 1993 and 1994,
as shown in the following chart:
Sewage Sludge Rate
(% Org-N in sludge)
1995 Growing
Season
Corn
Wheat
1994
4.8 ton/acre
(2.8% Org-N)
None
1993
2.6 ton/acre
(2.5% Org-N)
4.6 ton/acre
(2.5% Org-N)
For the wheat field, sewage sludge will be applied in the
fall after soybeans are harvested and before the winter
wheat is planted in the fall of 1994. For the corn fields,
sewage sludge will be applied in the spring of 1995
before corn is planted. No other source of N, except for
residual N from the 1994 and 1993 sludge applications,
are planned for the corn field. The wheat field will have
a 30 Ib/acre N credit from the preceding soybean crop
and a residual N credit for the 1993 sludge application.
No irrigation water will be used, and no manure applica-
tions have been made to either field.
The liquid sewage sludge will be surface applied after
soybean harvest before the soil is tilled, prior to the wheat
being planted. Incorporation of the sludge will be within 0-1
day, and experience with animal manure suggests that
30% of the NH4-N is typically lost by ammonia volatiliza-
tion. Therefore, 70% will be conserved and available for
plants to use, so K^ = 0.7. For the corn field, the liquid
sludge will be injected into the soil, so K^ = 1.0.
7.5.1 Calculation of Agronomic N Rate for
Each Field
Mineralization of PAN from the Org-N in this anaerobi-
cally digested sewage sludge is assumed to be the
82
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same as the Kmin values in Table 7-7 suggest, i.e., 20%
the 1st year, 10% the 2nd, and 5% the 3rd. Since the
NO3-N content is negligible (< lib/ton), it is not included
for calculating the PAN for this sewage sludge.
Total N = 3.9% x 20 = 78 Ib/ton
NO3-N = 200/kg x 0.002 = 0.4 Ib/ton
NH4-N = 1.2% x 20 = 24 Ib/ton
Org-N = 78 - 24 = 54 Ib/ton
For the wheat field where sewage sludge is to be sur-
face applied:
PAN = Kvol (NH4-N) + Kmin (Org-N) =
0.7 (24 Ib/ton) + 0.20 (54 Ib/ton) =
17 + 11 =
28 Ib/ton
For the corn field where sludge is to be injected:
PAN = Kvol (NH4-N) +
1.0 (24 Ib/ton)
24 + 11 =
35 Ib/ton
Kmin (Org-N) =
* 0.20 (54 Ib/ton)
To calculate the residual N mineralized from previous
sewage sludge applications, the Worksheet 1 chart is
completed for each field, as shown in Figure 7-3. As
indicated in Section 7.5 above, the wheat field had
sewage sludge applied in 1993, and the corn field re-
ceived sludge applications in 1993 and 1994.
Forthe wheat field, Org-N originally applied in 1993 was:
Org-N = 4.6 ton/acre x 20 (2.5% Org-N) =
4.6 ton/acre x 50 Ib/ton = 230 Ib Org-N/acre
Forthe corn field, Org-N originally applied in 1993 and
1994 was:
1993: Org-N = 2.6 ton/acre x 20 (2.5% Org-N) =
2.6 ton/acre x 50 Ib/ton =
130 Ib Org-N/acre
1994: Org-N = 4.8 ton/acre x 20 (2.8% Org-N) =
4.8 ton/acre x 56 Ib/ton =
270 Ib Org-N/acre
Therefore, as the Worksheet 1 charts show (Figure 7-3),
the PAN credit to use in Worksheet 2 for the wheat field
due to previous sewage sludge application is 8 Ib N/acre.
The PAN credit to use in Worksheet 2 forthe corn field due
to previous sewage sludge applications is 27 Ib N/acre.
The agronomic N rate can now be calculated for the
wheat field using Worksheet 2, as shown in Figure 7-4.
The legume credit of 30 Ib N/acre for the previous
soybean crop is shown on line 2.a, and the residual
sludge N credit is written on line 2.d. The total N credits
of 38 Ib/acre are subtracted from the fertilizer N recom-
mendation to get the adjusted N requirement. This re-
maining N requirement is then divided by the PAN cal-
culated earlier in this section forthe wheat field, i.e., 28
Ib N/ton, to get an agronomic N sludge rate of 1.9 dry
ton/acre. This rate will be equivalent to:
1 9 dry ton 100 wet ton (i.e., 4.8% solids )
x ^— x
acre 4.8 dry ton
2,000 Ib
wet ton 8.34 Ib
= 9,500 gallons/acre
A separate Worksheet 2 can be used to calculate the
agronomic rate forthe corn field, as shown in Figure 7-5.
The only N credit for this field is the residual sludge N
credit shown on line 2.d., which is subtracted from the
fertilizer N recommendation to get the adjusted N re-
quirement (i.e., 163 Ib N/acre). Dividing this requirement
by the PAN/ton calculated earlier forthe corn field, i.e.,
35 Ib N/ton, will obtain the agronomic N sludge rate of
4.7 dry ton/acre. This rate can be converted to a wet
weight basis, as was done for the wheat field, which is
equivalent to 23,500 gallons/acre. This amount of liquid
cannot be injected in a single application, so two appli-
cations of ~12,000 gal/acre each will be needed.
7.5.2 Calculation of Long-Term Pollutant
Loadings and Maximum Sewage
Sludge Quantities
By comparing the pollutant concentrations in this design
example to the Part 503 limits (see Chapter 3), the
reader will find that all trace element levels in the sew-
age sludge meet the "pollutant concentration limits" ex-
cept copper. Therefore, CPLR limits must be met for this
sewage sludge. Utilizing the "maximum sewage sludge
allowed" equation from Section 7.4.4.3 and the CPLRs
from Table 7-9, the total quantity of sludge that could be
applied before exceeding the CPLR limit for each pollu-
tant can be estimated:
Arsenic Max. sludge = 37 Ib/acre -^
0.002 (8 mg/kg) = -2,300 dry
ton/acre
Cadmium Max. sludge = 35 Ib/acre -^
0.002 (10 mg/kg) = 1,750 dry
ton/acre
Chromium Pollutant limits will most likely be
deleted from Part 503 rule
Copper Max. sludge = 1,300 Ib/acre +
0.002 (1,700 mg/kg) = 382 dry
ton/acre
Lead Max. sludge = 270 Ib/acre +
0.002(150 mg/kg) = 900 dry
ton/acre
83
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Mercury Max. sludge = 15 Ib/acre +
0.002 (2 mg/kg) = 3,750 dry
ton/acre
Molybdenum Currently, no CPLR is required
for Mo.
Nickel Max. sludge = 380 Ib/acre -^
0.002 (49 mg/kg) = -3,900 dry
ton/acre
Selenium Max. sludge = 90 Ib/acre -^
0.002 (15 mg/kg) = 3,000 dry
ton/acre
Zinc Max. sludge = 2,500 Ib/acre -^
0.002 (1,200 mg/kg) = ~1,040 dry
ton/acre
Assuming this particular sewage sludge continued
to have the same concentrations overtime, Cu would
continue to be the limiting pollutant. The pollutant load-
ings for each individual sewage sludge application
must be determined and recorded to keep a cumulative
summation of the total quantity of each pollutant that
has been added to each field receiving this sewage
sludge. To calculate the quantity of each pollutant
applied, the following equation from Section 7.4.4.3
can be used:
Sludge rate (dry ton/acre) x 0.002 (mg/kg pollu-
tant) = Ib pollutant/acre
For the two agronomic N rates calculated in Section
7.5.1, the amounts of each pollutant added by the sew-
age sludge are shown in Table 7-10.
Table 7-10. Amounts of Pollutants Added by Sewage Sludge
in Design Example
Pollutant
Arsenic
Cadmium
Chromium3
Copper
Lead
Mercury
Molybdenuma
Nickel
Selenium
Zinc
Cone, in
Sludge
mg/kg
8
10
-
1,700
150
2
-
49
15
1,200
Wheat Field
(1.9 ton/acre)
Corn Field
(4.7 ton/acre)
Ib/acre
0.030
0.038
-
6.5
0.57
0.0076
-
0.19
0.057
4.6
0.075
0.094
-
16
1.4
0.019
-
0.46
0.14
11
1 Limits for chromium will most likely be deleted from Part 503. Currently,
no calculation or recordkeeping for a CPLR is required for Mo.
These quantities would be added to the cumulative total
kept for each field receiving any sewage sludge that is
meeting CPLRs.
The approximate number of years that sewage sludge
(of the quality assumed in this design example) could be
applied before reaching the CPLR can be estimated. If
the pollutant concentrations remain the same and an
average, annual application rate is assumed, the maxi-
mum sludge quantity calculated above for the most
limiting pollutant (i.e., Cu) can be used to estimate the
number of years a site could be continuously utilized.
For this calculation, we will assume an average rate of
3.3 ton/acre/year, obtained by averaging the agronomic
N rates for the wheat field and the corn field [i.e., (1.9 +
4.7) -^ 2]. Using the following equation, the number of
years can then be estimated:
Max. sludge allowed -^ average annual rate =
number of years:
382 dry ton/acre -^ 3.3 dry ton/acre/year = ~116 years
Thus, these preliminary calculations indicate that Part
503 CPLR limits will likely not constrain the application
of sewage sludge if its quality was similar to that used
in this design example.
If the concentration of Cu was reduced until it met the
Part 503 pollutant concentration limits and all other pol-
lutant concentrations remained constant, the CPLRs
would no longer have to be recorded to comply with the
503 regulation (see Chapter 3).
7.5.3 Calculation of Agronomic P Rate for
Each Field
The equation from Section 7.4.4.2 can be used to cal-
culate the agronomic P rate for the wheat field and corn
field used in this design example. For the anaerobic
sewage sludge containing 1.9% total P, plant available
P2O5 can be estimated:
Total P2O5/dry ton = 1.9% x 20 x 2.3 =
87 Ib P2Os/dry ton
Avail. P2Os/dry ton = 0.5 (87 Ib total P2Os/dry ton) =
-44 Ib P2Os/dry ton
For the wheat field, the agronomic P rate is calculated
as follows:
84
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Wheat Field - 1995 Growing Season
A. Year of
Growing Season
0-1 (1993
Application)
1-2 (1994)
2-3 (1995)
B. Starting Org-
N (Ib/acre)
C. Mineralization
Rate (K,^)
1993 Sludge Appli
230
184
166
0.20
0.10
0.05
D. Mineralized
Org-N (Ib/acre)
E. Org-N
Remaining
(Ib/acre)
cation
46
18
8
184
166
158
PAN credit for the 1993 sludge application during 1995 is 8 Ib N/acre.
Corn Field - 1995 Growing Season
A. Year of
Growing Season
0-1 (1993
Application)
1-2 (1994)
2-3 (1995)
0-1 (1994
Application)
1-2 (1995)
2-3 (1996)
B. Starting Org-
N (Ib/acre)
C. Mineralization
Rate (K^)
1993 Sludge Apoli
130
104
94
0.20
0.10
0.05
1994 Sludge Appli
270
216
194
0.20
0.10
0.05
D. Mineralized
Org-N (Ib/acre)
E. Org-N
Remaining
(Ib/acre)
cation
26
10
5
104
94
89
cation
54
22
10
216
194
184
PAN credit for the 1995 growing season on this field due to sewage sludge applications in 1993 and 1994
is: 5 + 22 = 27 Ib N/acre.
Figure 7-3. Worksheet 1 calculations to determine residual N credits for previous sewage sludge applications.
85
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Worksheet 2
Nitrogen Budget Sheet for Determining the Agronomic N Rate
for Sewage Sludge Applications
Symbols and Abbreviations Used
Org-N — Organic N content of the sewage sludge obtained from analytical testing and determined by
subtracting (NO3-N + NH4-N) from total N, usually given in percent (%); the resulting
concentration should be converted to Ib/ton (dry weight basis).
NH4-N = Ammonium N content of the sewage sludge obtained from analytical testing and usually
given in percent (%); then convert to Ib/ton (d.w. basis).
NO3-N = Nitrate N content of the sewage sludge obtained from analytical testing and often given in
mg/kg; then convert to Ib/ton (d.w. basis).
= Mineralization rate for the sewage sludge expressed as a fraction of the sludge Org-N
expected to be released as PAN for the year being calculated; example mineralization rates for
different sewage sludges can be found in Table 7-7.
= Volatilization factor for estimating the amount of NH4-N remaining after loss to the
atmosphere as ammonia and expressed as a fraction (e.g., if K,,^ = 1.0, 100% of the NH4-N is
retained and contributes to PAN; if K^ = 05, then (0.5 x NH4-N content) estimates the amount
of NH4-N contributing to PAN).
PAN = Plant-available N which is determined by calculating: NO3-N + K^NH^N) + K^Org-N)
Helpful Conversions
mg/kg x 0.002 = IbAon Ib/acre x 1.12 = kg/ha Ib/ton -=- 2 = kg/mt
% x 20 = Ib/ton ton/acre x 2.24 = mt/ha (mt = metric ton = 1000 kg)
1. Total N requirement of crop to be grown (obtain information from Cooperative Extension 90 Ib/acre
Service agricultural agents, USDA-Natural Resource Conservation Service or other
agronomy professionals).
2. Nitrogen provided from other N sources added or mineralized in the soil
a. N from a previous legume crop (legume credit) or green manure crop 30 Ib/acre
b. N from supplemental fertilizers already, or expected to be, added - Ib/acre
c. N that will be added by irrigation water -- Ib/acre
d. Estimate of available N from previous sludge applications (from Worksheet 1) 8 Ib/acre
e. Estimate of available N from a previous manure application (obtain mineralization — Ib/acre
factors from land-grant university to calculate similarly as for previous sewage
sludge applications).
f. Soil nitrate test of available N present in soil [this quantity can be substituted - Ib/acre
in place of (a + d + e), if test is conducted property; do not use this test value if
estimates for a, d and e are used]
Total N available from existing, expected, and planned sources of N (add a+b+c+d+e orb+c+f) 38 Ib/acre
3. Loss of available N by denitrification, immobilization, or NH4* fixation (check with state regulatory - Ib/acre
agency for approval, before using this site-specific factor).
4. Calculate the adjusted fertilizer N requirement for the crop to be grown (subtract Total N for (2) 52 Ib/acre
from (1); amount for (3) can be added to this difference, only if (3) is approved for this additional adjustment).
Figure 7-4. Calculation of the agronomic N rate for the wheat field.
86
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Worksheet 2 (continued)
5. Determine the PAN/dry ton for the sludge that will be applied 28 Ib/ton
[i.e., NO,-N + K^ (NH,-N) + K^. (Org-N) = PAN]
6. Calculate the agronomic N rate of sewage sludge (Divide (4) by (5)) 1.9 ton/acre
7. Convert the rate of sewage sludge in dry tons/acre into gallons/acre, cubic yards/acre, or wet tons/acre,
since the sludge will be applied to land as a liquid or as a wet cake material.
Figure 7-4. Calculation of the agronomic N rate for the wheat field (continued).
87
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Worksheet 2
Nitrogen Budget Sheet for Determining the Agronomic N Rate
for Sewage Sludge Applications
Symbols and Abbreviations Used
Org-N = Organic N content of the sewage sludge obtained from analytical testing and determined by
subtracting (NO3-N + NH4-N) from total N, usually given in percent (%); the resulting
concentration should be converted to Ib/ton (dry weight basis).
NH4-N = Ammonium N content of the sewage sludge obtained from analytical testing and usually
given in percent (%); then convert to Ib/ton (d.w. basis).
NO3-N = Nitrate N content of the sewage sludge obtained from analytical testing and often given in
mg/kg; then convert to Ib/ton (d.w. basis).
= Mineralization rate for the sewage sludge expressed as a fraction of the sludge Org-N
expected to be released as PAN for the year being calculated; example mineralization rates for
different sewage sludges can be found in Table 7-7.
= Volatilization factor for estimating the amount of NH4-N remaining after loss to the
atmosphere as ammonia and expressed as a fraction (e.g., if K^j = 1.0, 100% of the NH4-N is
retained and contributes to PAN; if K,,,,, = 0.5, then (0.5 x NH4-N content) estimates the amount
of NH4-N contributing to PAN).
PAN = Plant-available N which is determined by calculating: NO3-N + K,,ol(NH4-N) + Kmin(Org-N)
Helpful Conversions
mg/kg x 0.002 = Ib/ton Ib/acrex 1.12 = kg/ha Ib/ton + 2 = kg/mt
% x 20 = Ib/ton ton/acre x 2.24 = mt/ha (mt = metric ton = 1000 kg)
1. Total N requirement of crop to be grown (obtain information from Cooperative Extension 190 Ib/acre
Service agricultural agents, USDA-Natural Resource Conservation Service or other
agronomy professionals).
2. Nitrogen provided from other N sources added or mineralized in the soil
a. N from a previous legume crop (legume credit) or green manure crop - Ib/acre
b. N from supplemental fertilizers already, or expected to be, added -- Ib/acre
c. N that will be added by irrigation water -- Ib/acre
d. Estimate of available N from previous sludge applications (from Worksheet 1) 27 Ib/acre
e. Estimate of available N from a previous manure application (obtain mineralization -- Ib/acre
factors from land-grant university to calculate similarly as for previous sewage
sludge applications).
f. Soil nitrate test of available N present in soil [this quantity can be substituted -- Ib/acre
in place of (a + d + e), if test is conducted properly; do not use this test value if
estimates for a, d and e are used]
Total N available from existing, expected, and planned sources of N (add a+b+c+d+e or b+c+f) 27 Ib/acre
3. Loss of available N by denitrification, immobilization, or NH4+ fixation (check with state regulatory — Ib/acre
agency for approval, before using this site-specific factor).
4. Calculate the adjusted fertilizer N requirement for the crop to be grown (subtract Total N for (2) 163 Ib/acre
from (1); amount for (3) can be added to this difference, onfy if (3) is approved for this additional adjustment).
Figure 7-5. Calculation of the agronomic N rate for the corn field.
88
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Worksheet 2 (continued)
5. Determine the PAN/dry ton for the sludge that will be applied 35 Ib/ton
[i.e., NO3-N + K,., (NH4-N) + K^. (Org-N) = PAN]
6. Calculate the agronomic N rate of sewage sludge (Divide (4) by (5)) 4.7 ton/acre
7. Convert the rate of sewage sludge in dry tons/acre into gallons/acre, cubic yards/acre, or wet tons/acre,
since the sludge will be applied to land as a liquid or as a wet cake material.
Figure 7-5. Calculation of the agronomic N rate for the corn field (continued).
89
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Preq = Fertilizer P2Os Recommendation =
80 Ib P2Os/acre, so
Agronomic P rate = Preq + Avail. P2Os/dry ton =
80 Ib P2Os/acre ^ 44 Ib P2Os/dry ton =
~1.8 dry ton/acre
For the corn field, the agronomic P rate would be:
Preq = 60 Ib P2Os/acre, so
Agronomic P rate = 60 Ib P2Os/acre +
44 Ib P2Os/dry ton = ~1.4 dry ton/acre
Since the agronomic P rate for each field is less
than the agronomic N rate, these rates could be se-
lected to use. The consequence of utilizing P rates
rather than N rates is that less sewage sludge per acre
will normally be applied, so more land area will be
needed to apply the total sludge produced by the treat-
ment works. For example, the design example treat-
ment works generates 7,300 dry ton/year (i.e., 20 dry
ton/day x 365 days/year). If sludge was applied at a rate
equal to the agronomic P rate for the corn field, about
5,220 acres/year would be needed to apply all the
sludge produced (i.e., 7,300 dry ton/year -^ 1.4 dry
ton/acre). But if sludge was applied at the agronomic N
rate for the corn field, only about 1,560 acres would be
needed to apply all the sludge produced (i.e., 7,300 dry
ton/year -^ 4.7 dry ton/acre).
Alternatively, continuously using the agronomic N rate
would result in excess P (beyond what the crop needs)
being applied. As was discussed in Section 7.4.4.2, soil
P fertility levels will likely be increased overtime. Unusu-
ally high soil P levels can potentially increase the risk of
nonpoint source pollution losses of P to surface waters
and contribute to undesirable water quality. A second
consequence is that supplemental N fertilizers must be
added to fulfill the remaining N needs of the crop not
supplied by the sewage sludge. The quantity of addi-
tional N can be calculated by returning to Worksheet 2
and multiplying the PAN/dry ton times the rate of sewage
sludge applied, and then subtracting this PAN/acre
value from the adjusted fertilizer N requirement.
For example, using Figure 7-5 for the corn field and
assuming the agronomic P rate was used (i.e., 1.4 dry
ton/acre), the supplemental N fertilizer needed is:
35 Ib PAN/dry ton x 1.4 dry ton/acre =
49 Ib PAN/acre
163 Ib N/acre - 49 Ib N/acre = 114 Ib N/acre
7.5.4 Calculation of Supplemental K
Fertilizer To Meet Crop Nutrient
Requirements
Because K is a soluble nutrient, most of the K received
by a treatment works is discharged with effluents. Con-
sequently, sewage sludges will contain low concentra-
tions of this major plant nutrient. Therefore, fertilizer
potash (K2O) or other sources of K will be needed to
supplement the quantities of K2O added by sewage
sludge applications, particularly over the long-term.
The amount of sewage sludge K2O applied can be
calculated from sludge analysis information in a similar
manner as is done for P2O5 (Section 7.4.4.2). Since K
is readily soluble, however, all the K in sewage sludge
is assumed to be available for crop growth compared to
P, which is assumed to be about 50% available to plants.
As with P, soil fertility testing can be used to monitor
these K2O additions and determine additional K2O that
is needed for crops.
The quantity of K2O that can be credited against the K2O
fertilizer recommendation is calculated using the follow-
ing equation:
Sludge K2
-------
7.5.5 A dditional Considerations for Land
Application Program Planning
To simplify the design example, only two fields with differ-
ent crops were considered. For most land application
programs, however, sewage sludge will be applied to more
than two crops and to many individual fields. Application
rate calculations should be made for each field receiving
sewage sludge as a detailed plan is developed. For this
design example, additional crops could be oats, soybeans,
and forages for hay and pasture. Crop rotations and
relative acreages of each crop will vary from one crop
producer to another. Also keep in mind that farms with
livestock will be producing animal manure nutrients in
addition to the sewage sludge nutrients used for sup-
plying plant nutrient requirements on the acreage avail-
able for growing crops.
7.6 References
Adriano, D.C., A.C. Chang, and R. Sharpless. 1974. Nitrogen loss
from manure as influenced by moisture and temperature. J. En-
viron. Qual. 3:258-261.
Aguilar, R., and E. Aldon. 1991. Seasonal water flux and potential for
leaching in a semiarid rangeland soil. In: Proceedings of the Fifth
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Chapter 8
Process Design for Forest Land Application Sites
8.1 General
Sewage sludge application to forests can greatly in-
crease forest productivity. Research at the University of
Washington showed that for some tree species, the use
of sewage sludge as a fertilizer resulted in excellent and
prolonged increases in height and diametergrowth com-
pared to controls (Henry et al., 1993). Sewage sludge
amends the soil by providing nutrients, especially nitro-
gen (N) and phosphorus (P), that are frequently limited
in forest soils, and by improving soil textural charac-
teristics. Sewage sludge addition can improve short-
term soil productivity because it provides an immediate
supply of virtually every nutrient needed for plant growth
in an available form. In addition, the fine particles and
organics in sewage sludge can immediately and perma-
nently enhance soil moisture and nutrient-holding char-
acteristics. In the long-term, sewage sludge provides a
continual slow release input of nutrients as the organics
decompose.
Forest soils are in many ways well suited to sewage
sludge application. They have high rates of infiltration
(which reduce runoff and ponding), large amounts of
organic material (which immobilize metals from the sew-
age sludge), and perennial root systems (which allow
year-round application in mild climates). Although forest
soils are frequently quite acidic, research has found no
problems with metal leaching following sewage sludge
application (U.S. EPA, 1984).
One major advantage of forest application over agricul-
tural application is that forest products (e.g., wild edible
berries, mushrooms, game, and nuts) are an insignifi-
cant part of the human food chain. In addition, in many
regions, forest land is extensive and provides a reason-
able sewage sludge land application alternative to agri-
cultural cropland. The primary environmental and public
health concern associated with forest application is pol-
lution of water supplies. In many areas, particularly in
the western states, forest lands form crucial watersheds
and ground-water recharge areas. Contamination of
water supplies by nitrates can be prevented by limiting
sewage sludge application rates according to the nitro-
gen needs of the crop (as required by the Part 503
regulation), in this case trees (approximately 10 to 100
metric tons dry weight per hectare [t DW/ha] in a single
application every 3 to 5 years).
Application of sewage sludge to forest land is feasible
on commercial timber and fiber production lands, federal
and state forests, and privately owned woodlots. Sew-
age sludge use in nurseries, green belt management,
and Christmas tree production also is possible.
This chapter discusses sewage sludge applications to
forest land for three common situations: (1) recently
cleared forest land that has not been planted, (2) young
plantations (planted or coppice), and (3) established
forest stands. Each of these cases presents different
design issues and opportunities. Public participation
considerations are a critical aspect of forest land appli-
cation systems, as discussed in Chapter 12.
8.2 Regulatory Requirements and Other
Considerations
The federal Part 503 regulatory requirements associ-
ated with land application of sewage sludge to forest
lands regarding metals, pathogens, and nitrogen are
discussed in Chapter 3. Issues particularly relevant to
land application at forest sites are discussed below.
8.2.1 Pathogens
Organisms present in forest soils are responsible for the
relatively quick die off of pathogens following sewage
sludge application to a forest site. Microorganisms pre-
sent in the sewage sludge are initially filtered out by the
soil and forest floor and then replaced by the native
organisms of the soil. The survival time for most micro-
organisms following land application of sewage sludge
to forests typically is very short but depends on a variety
of soil and climatic conditions including temperature,
moisture content, and pH.1 For a further discussion of
pathogen die off, see Chapter 4.
Pathogen-related concerns involving windborne con-
tamination may arise when spray application of liquid
1 Henry, Charles. Biosolids Utilization in Forest Lands. Draft report.
University of Washington, Eatonville, WA.
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sewage sludge on forest lands is used. Precautions can
be taken to minimize exposure during and after spray
application, such as restricting public access from the
area downwind during the spray application and for
several hours after spraying is completed, and consid-
ering wind velocity so that applications can be control-
led. Generally, aerosols will not travel far in an
established, non-dormant forest because of interception
by the leaves and breakup of wind currents.
8.2.2 Nitrogen Dynamics
As with other types of land application sites, nitrogen
needs at forest sites (i.e., N needed by trees and under-
story) are an essential component of the land application
system. Sewage sludge at a forest site must be applied
at a rate that is equal to or less than the agronomic rate
forN, as required by the Part 503 regulation. Key factors
regarding nitrogen levels at forest sites include nitrogen
uptake by plants; mineralization of nitrogen; ammonia
volatilization; denitrification; soil immobilization rates; ni-
trogen leaching; and temperature-related effects. These
factors are discussed in Section 8.9 below, particularly
as they affect determination of sewage sludge applica-
tion rates at forest sites.
8.3 Effect of Sewage Sludge
Applications on Tree Growth and
Wood Properties
8.3.1 Seedling Survival
Seedlings of deciduous species and many conifers, in-
cluding Douglas fir and Sitka spruce, have shown excel-
lent tolerance to sewage sludge in demonstration
projects. At relatively light application rates (i.e. agro-
nomic loadings), seedling mortality is not a problem, and
planting should be possible soon after sludge application.
8.3.2 Growth Response
Growth response has been documented on a number of
stands of Douglas-fir in Washington (Henry etal., 1993).
Growth responses can range from 2% to 100% for
existing stands, and over 1,000% for trees planted in
soils amended with heavy applications of sewage
sludge. The magnitude of this response depends on site
characteristics and tree stand ages. Some of the main
site differences affecting growth response include:
• Site class. In both young Douglas-fir plantations and
older stands, greater growth responses have been
found where the trees are doing poorly due to lack
of nutrients.
• Thinned versus unthinned stands treated with sew-
age sludge. There appears to be little difference in
total wood produced in unthinned versus thinned stands
that have received sewage sludge applications. In thinned
stands, however, growth is concentrated in trees with
larger diameters.
• Response by species. Most tree species grow faster
in soil treated with sewage sludge; however, some
species respond dramatically while others show only
a slight response. Excellent response has been
shown by black locust, European alder, hybrid poplar,
Japanese larch, and catalpa (Sopper, 1993).
Greater growth responses have been seen when trees
have been planted directly in soil already amended with
large amounts of sewage sludge, such as a soil recla-
mation site. In this case, special management practices
are required. An excellent example of this type of appli-
cation is Christmas tree plantations.
Because sewage sludge application to forest sites is
relatively new and limited data have been collected, it is
difficult to estimate the value added to a forest site when
sewage sludge is land applied. A conservative estimate
of the value of sewage sludge could be based on the
value of the nitrogen fertilizer potential alone, which
would be approximately $30/dry ton of sewage sludge.
Preliminary studies, however, have shown a greater
growth response to sewage sludge than to chemical
nitrogen fertilizer. Additionally, the effect appears to be
much longer lasting, with some studies showing contin-
ued growth response 8 years after application.
8.3.3 Wood Quality
Accelerated tree growth (200 to 300 percent) resulting
from sewage sludge addition has the potential for
changing basic wood characteristics, including specific
gravity, shrinkage, fibril angle, and certain mechanical
properties. Research indicates that both positive and
negative effects on wood quality occur in trees grown on
sewage sludge-amended soil. In some studies, static
bending tests, which show combined effects, have indi-
cated no significant change when the strength proper-
ties of specimens cut from trees grown on sewage
sludge-amended soils were compared with specimens
of wood produced without sewage sludge. Other studies
have shown a 10 to 15 percent reduction in density and
in modulus of rupture and elasticity.2
8.4 Effect of Sewage Sludge Application
on Forest Ecosystems
Although immediately after land application of sewage
sludge a site is greatly altered in appearance, within six
months understory growth often is much more vigorous
than before sewage sludge application. Increased un-
derstory also is typically higher in nutrients and can
provide better habitat for wildlife. A number of wildlife
studies have found increased populations of animals on
• See footnote 1.
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sites receiving sewage sludge compared to nearby sites
that were not amended with sewage sludge (Henry and
Harrison, 1991).
8.5 Forest Application Opportunities
8.5.1 Forest Stand Types
The land application designer may have the option of
selecting among the following types of forest sites for
sewage sludge addition:
• Sites recently cleared prior to replanting.
• Young plantations of an age conducive to sewage
sludge application over the tops of trees.
• Established forests.
The advantages and disadvantages associated with each
type of forest site are summarized in Tables 8-1 to 8-3.
8.5.1.1 Applications Prior to Planting
Clearcuts offer the easiest, most economical sites for
sewage sludge application. Because application takes
place prior to tree planting, many agricultural sewage
sludge application methods can be used. Vehicles de-
livering sewage sludge from the treatment plant can
discharge semi-solid sewage sludge (15% or more sol-
ids) directly on the land, followed by spreading by a
dozer and disking. Ease of delivery depends on the
amount of site preparation (stump removal, residual
debris burning, etc.), slopes, soil conditions, and
weather. Site preparation and sewage sludge charac-
teristics are also major factors in application technique
(e.g., temporary spray irrigation systems; injectors and
splash plates for liquid material; manure spreaders for
solid material).
While sewage sludge application is easier to perform on
clearcuts, these sites also may require additional man-
agement practices to control grasses and rodents such
as voles. If application to a clearcut is planned, a pro-
gram of periodic disking and herbicides should be con-
ducted to control grasses and rodents. Tree trunk
protection devices also are available to provide a barrier
against rodent girdling. Additionally, fencing or bud cap-
ping may be required to prevent excessive deer brows-
ing. Sewage sludge injection into the soil may minimize
plantation establishment problems.
8.5.1.2 Applications to Young Stands
Application of sewage sludge to existing stands typically
is made by a tanker/sprayer system, which can apply
sewage sludge with an 18% solids content over the tops
of the trees (canopy) 125 feet (40 m) into a plantation.
This method requires application trails at a maximum of
250 feet (80 m) intervals. King County Metro, Washing-
ton (including Seattle), has developed a throw spreader
that is capable of applying a dewatered sewage sludge
up to 70 m over a plantation. This method has greatly
reduced application costs and allows trail spacing of
greater distances (120 m with overlap for evenness of
applications). A good tree age or size for this type of
application are trees over 5 years or over 4 to 5 feet high
because they minimize maintenance otherwise needed
in clearcut areas. Timing of applications may be impor-
tant with over-the-canopy applications because sewage
sludge sticking on new foliage could retard the current
year's growth during the active growth season.
Table 8-1. Sewage Sludge Application to Recently Cleared Forest Sites
Advantages
1. Better access for sludge application equipment. Also, optimal access can be established for additional sludge application in the
future.
2. Possible option of incorporating the sludge into the soil (versus a surface application) if the site is sufficiently cleared.
3. Possible option of establishing a flooding or ridge and furrow sludge application system (versus spray application) if the site
topography is favorable.
4. Option to select tree species that show good growth and survival characteristics on sludge-amended sites.
5. Often easier to control public access to the site because cleared areas are less attractive than wooded areas for typical forest
recreational activities.
Disadvantages
1. Seedlings have low nitrogen uptake rates. If nitrate contamination of an underlying potable aquifer is a potential problem, initial
sludge applications must be small relative to the volume of sludge application to established forests.
2. An intensive program of weed control is necessary since the weeds grow faster than the seedlings and compete for nutrients,
space, light, etc. Use of herbicides and cultivation between tree rows usually is required for the first 3 to 4 years.
3. Intensive browsing by deer and damage to young trees by voles and other pest species may require special control measures,
since these animals may selectively feed upon trees grown on sludge-amended sites due to their higher food value.
97
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Table 8-2. Sewage Sludge Application to Young Forest Plantations (Over 2 Years Old)
Advantages
1. Seedlings are established and more tolerant of fresh sludge applications.
2. Weed control is less of a problem than with cleared sites because of established trees and vegetation.
3. Nitrogen uptake by the trees is rapidly increasing, and acceptable sludge application rates can be higher on these sites over
aquifers than on recently cleared sites.
4. Access for sludge application equipment usually is still good.
5. Rapid growth response from most deciduous and many coniferous tree seedlings can be expected.
Disadvantages
1. Sludge application by spraying over the canopy may be restricted to those periods when the trees are dormant, to avoid the
problem of sludge clinging to foliage. Application during periods of the year when heavy rainfalls are common may potentially
alleviate this problem. In addition, sewage sludge applied to broad leaf species quickly dries and flakes off the leaves.
2. Some weed control will probably be necessary.
Table 8-3. Sewage Sludge Application to Closed Established Forest (Over 10 Years Old)
Advantages
1. Established forests are less susceptible to sludge-induced changes in vegetation (e.g., weed growth).
2. Excellent growth response can be expected to result from the increased nutrients.
3. Sludge application by spraying can be done under the tree foliage, so it is not necessary for the trees to be dormant.
4. During precipitation, rapid runoff of storm water containing sludge constituents is unlikely because the forest canopy breaks up the
rain and accumulated organic debris on the forest floor absorbs runoff.
5. Forest soils under established forests usually have high C-to-N ratios resulting in excellent capability to immobilize (store)
nitrogen for slow release in future years. Consequently, it often is feasible to make an initial heavy application of sludge, e.g.,
74 t/ha (33 T/ac), and achieve tree growth response for up to 5 years without subsequent sludge applications.
Disadvantages
1. Access by sludge application vehicles into a mature forest often is difficult. The maximum range of sludge spray cannons is about
40 m (120 ft). To obtain fairly uniform coverage, the spray application vehicle requires access into the site on a road grid, spaced
at approximately 75-m (250-ft) intervals. Most established forest sites do not have such grid-like roads. As a result, access roads
must be cut through the forest, or the selected sludge application area(s) are largely restricted to narrow 36-m (120-ft) strips on
both sides of existing roads. Access into commercial forests is usually easier than into publicly owned forest lands.
2. In an established publicly owned forest, it may not be advantageous to accelerate vegetation with sludge applications. In contrast,
commercial forest operations desire faster growth of trees.
Notes:
t = metric tonnes
T = English tons (short)
Liquid sewage sludge also has been successfully applied
using a sprinkler irrigation system. Clogging of nozzles has
been the major drawback to this method. Manure spread-
ers are capable of applying dewatered sewage sludge
which cannot be sprayed. Depending on the range of
sewage sludge trajectory, application trails may need to be
at closer intervals than with other methods.
tures are low and neither N mineralization (transforma-
tion of organic N to NHjj) or nitrification (transformation
of MM} to NO§) occurs significantly. Thus nutrients are
effectively "stored" until the next growing season.
8.5.1.3 Applications to Mature Stands
It is recommended that sewage sludge applications take
place during the time that tree growth is reduced, but
uptake of nutrients also is reduced during this time.
When sewage sludge is first applied to the soil, the
available N is in the NHJ form, which does not leach. In
addition, in some cases such as in northern cool cli-
mates, during the non-growing season soil tempera-
Applications to older stands have the advantage that
sewage sludge can be applied year-round. Because
spraying takes place under the tree foliage, no foliage
will be affected. Application methods are similarto those
described for young plantations. In many cases, how-
ever, stands are not in rows, which may eliminate some
of the alternatives available for plantations.
98
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8.5.2 Christmas Tree Plantations
One clearcut application scenario that has worked well
in the state of Washington is the use of sewage sludge
application in Christmas tree stands. Typically, a high
level of maintenance is common, and weed estab-
lishment and rodent populations are minimized as
standard practice.
8.6 Equipment for Sewage Sludge
Application at Forest Sites
8.6.1 Transfer Equipment
Sewage sludge usually comes from the wastewater
treatment plant (WWTP) in an over-the-road vehicle.
Once at the site it is often stored, at least temporarily,
before being transferred to an application vehicle. Ex-
ceptions to storage are when a multi-purpose high-
way/application vehicle is used (generally by smaller
facilities) and when applications are close to the WWTP.
The two basic mechanisms for transferring sewage
sludge from vehicles to storage facilities are (1) direct
dumping, and (2) pumping. The transfer method suitable
for a particular site depends on how liquid the sewage
sludge is (i.e., how easy it is to pump), or the position
and configuration of the storage vessel (i.e., whether
gravity is sufficient to transfer the sewage sludge).
Direct dumping of sewage sludge is the easiest method
for unloading a trailer from a treatment plant. Gravity
dumping requires either using an in-ground storage fa-
cility or driving the truck onto a ramp above the storage
facility. Additionally, sewage sludge must be dilute
enough to flow from the trailer (<8% solids) or pressur-
ized tank (<15% solids), or the trailer bed must be tilted.
Pumping the sewage sludge can work if the sewage
sludge is liquid enough. Below 10% to 15% solids, most
sewage sludge flows as a semi-solid and can be fed through
a pump. Higher solids concentrations restrict or eliminate the
flow of sewage sludge to the pump. Centrifugal pumps can
be used for dilute sewage sludge (<10% to 13% solids),
or chopper-type centrifugal pumps may be able to pump
sewage sludge of up to 15% solids. If dewatered sewage
sludge (>15%) is brought to the site and a pump is to be
used to transfer the sludge, water must be added and
mixed with the sewage sludge before pumping is possible.
8.6.2 Application Equipment
There are four general types of methods for applying
sewage sludge to forests: (1) direct spreading; (2) spray
irrigation with either a set system or a traveling gun; (3)
spray application by an application vehicle with a spray
cannon; and (4) application by a manure-type spreader.
The main criteria used in choosing a system is the liquid
content of the sewage sludge. Methods 1, 2, and 3 are
effective for liquid sewage sludge (2% to 8% solids);
Methods 1 and 2 can be used for semi-solid sewage
sludge (8% to 18% solids); and only Method 4 is accept-
able for solid sewage sludge (20% to 40% solids). Table
8-4 lists these methods, their range of application, rela-
tive costs, and advantages and disadvantages. The
method used by most municipalities for forest applica-
tions is spray application by an application vehicle with
a mounted cannon, although King County Metro in
Washington state now applies a dewatered sewage
sludge with a throw spreader.
Many application vehicles have been developed for use in
agricultural applications. Most of these can be readily
modified for forest use by mounting a spray nozzle and
pump on the tank. Application vehicles can also be custom
made. Depending on the site needs, a specially designed
all-terrain vehicle can be used. In some cases, a used
heavy-duty truck chassis with a rear-mounted tank has
been modified for forest use. The application vehicle can
either be filled by a traveling tanker, directly from on-site
storage, or can itself be an over-the-road multi-purpose
(transport/application) vehicle. Once full, the application
vehicle moves into the forest over the roads or trails and
Table 8-4. Comparison of Different Application Systems for Forest Sites (Henry, 1991)
System and Range Relative Costs Advantages
Disadvantages
Sludge spreading and
incorporation range = 10' (3 m)
Spray irrigation:
Set irrigation systems
range = 30' - 200'
Traveling big gun
range = 200'
Low capital and O&M
High capital, low O&M
Moderate capital, low
O&M
Simple to operate; any
solids
Simple to operate
Simple to operate on
appropriate sites
Need cleared site; difficult plantation
establishment with some species
Frequent clogging; use only low %
solids; brush interferes
Frequent clogging; use only low %
solids; brush interferes
Application vehicle with
mounted cannon range = 125'
Manure-type spreader
range = 50'-200'
Low-moderate capital,
high O&M
Low capital and O&M
Any terrain; sludge up to
18% solids
Only effective way to apply
high % solids sludge
May need special trails
Limited to high % solids; trails may
need to be close together
O&M = operation and maintenance costs.
99
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unloads the sewage sludge in uniform thin layers while
the vehicle is either moving or stationary.
Considerations for on-site storage are discussed in
Chapter 14.
8.7 Scheduling
Sewage sludge applications to forest sites can be made
either annually or once every several years. Annual
applications are designed to provide N only for the
annual uptake requirements of the trees, considering
volatilization and denitrification losses and mineraliza-
tion from current and prior years. An application one
year followed by a number of years when no applica-
tions are made utilizes soil storage (immobilization) of
nitrogen to temporarily tie up excess nitrogen that will
become available in later years.
In a multiple-year (e.g., every 3 to 5 years) application
system, the forest floor, vegetation, and soil have a
prolonged period to return to normal conditions, and the
public can use the site for recreation in the non-applied
years. Application rates, however, are not simply an
annual rate multiplied by the number of years before
reapplication, but rather need to be calculated so that
no NO§ leaching occurs. If the sewage sludge is quite
liquid (<5% solids), annual applications may be pre-
ferred, since the water included with heavier applications
at low percent solids may exceed the soil's infiltration rate.
In this case surface sealing may occur, increasing the
potential for runoff as well as anaerobic conditions, which
can cause odor problems or stress the plants.
For liquid and semi-liquid sewage sludge, if the total
depth of an application is to be greater than approxi-
mately one-quarter of an inch, it is recommended that a
series of three or more partial applications (with the
number depending on the percent solids of the sludge)
be made rather than one heavy application. This prac-
tice allows more even applications to be made, provides
time for stabilization or drying of the sewage sludge to
occur, and is important for maintaining infiltration and con-
trolling runoff. The "rest" between applications will range
from 2 to 14 days depending on weather conditions.
Scheduling sewage sludge application also requires a
consideration of climatic conditions and the age of the
forest. High rainfall periods and/or freezing conditions
can limit sewage sludge applications in almost all situ-
ations. The Part 503 regulation prohibits bulk sewage
sludge from being applied to forest land that is flooded,
frozen, or snow-covered so that the sewage sludge
enters a wetlands or other surface waters. In addition,
vehicle access to steeper soils could potentially be too
difficult during the wet parts of the year. As discussed in
Section 8.5.1.2, all applications to young plantations
should be done when the trees are dormant (e.g., during
the late fall, winter, and early spring).
An application schedule for a 1-year period is shown in
Table 8-5 for a design in the Pacific Northwest. Using
such a schedule, it would be feasible to avoid the need
for storage, especially when alternative management
schemes are available. On-site storage, however, may
also be desirable.
Table 8-5.
Monthly Application Schedule for a Design in the
Pacific Northwest
Glacial Soil
Residual Soil
Young Established Young Established
Month Plantation Forest Plantation Forest
January
February
March
April
May
June
July
August
September
October
November
December
Aa
A
A
NA
NA
NA
NA
NA
NA
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
LA
LA
LA
NA
NA
NA
NA
NA
NA
LA
LA
LA
LA
LA
LA
A
A
A
A
A
A
LA
LA
LA
Abbreviations:
A =Site available, no limitations.
NA = Not available, damage will be caused by sludge on growing
foliage.
LA = Limited availably, periods of extended rain are to be
avoided due to vehicle access problems
8.8 Determining Sewage Sludge
Application Rates for Forest Sites
8.8.1 General
As with agricultural lands, sewage sludge application
rates at forest sites usually are based on tree N require-
ments. As discussed below, nitrogen dynamics of forest
systems are somewhat more complex than agricultural
systems because of recycling of nutrients in decaying
litterfall, twigs and branches, and the immobilization of
the MM} contained in sludge as a result of decomposition
of these materials. As with agricultural applications, con-
centrations of trace elements (metals) in some sewage
sludges may limit the cumulative amount of sewage
sludge that can be placed on a particular area (see
Chapter?, Section 7.4.4.3).
8.8.2 Nitrogen Uptake and Dynamics in
Forests
In general, uptake and storage of nutrients by forests
can be as large as that of agricultural crops if the system
is correctly managed and species are selected that
100
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respond to sewage sludge. The trees and understory
utilize the available N from sewage sludge, resulting in
an increase in growth. There is a significant difference
between tree species in their uptake of available N. In
addition, there is a large difference between the N up-
take by seedlings, vigorously growing trees, and mature
trees. (One study found that in young Douglas-fir, uptake
can be up to 100 Ib-N/ac/yr when the trees fully occupy
the site, but as low as 25 Ib-N/ac/yr in old Douglas-fir
stands [Dyck et al., 1984]). Finally, the amount of vege-
tative understory on the forest floor will affect the uptake
of N; dense understory vegetation markedly increases
N uptake.
Table 8-6 provides estimates of annual N uptake by the
overstory and understory vegetation of fully established
and vigorously growing forest ecosystems in selected re-
Table 8-6. Estimated Annual Nitrogen Removal
by Forest Types
Forest Type
Tree Age Average N Uptake
(years) (Ib/ac/yr) (kg/ha/yr)
Eastern Forests
(Irrigated Wastewater)
Mixed Hardwoods 40-60
Red Pine 25
Old Field with White 15
Spruce Plantation
Pioneer Succession 5-15
Aspen Sprouts
Southern Forests
(Irrigated Wastewater)
Mixed Hardwoods 40-60
Southern Pine with No 20
Understory
(mainly Loblolly)
Southern Pine with 20
Understory
(mainly Loblolly)
Lake States Forests
(Irrigated Wastewater)
Mixed Hardwoods 50
Hybrid Poplar3 20
Western Forests
Irrigated Wastewater
Hybrid Poplar 4-5
Douglas Fir Plantation 15-25
Sludge Application
Hybrid cottonwood 5
Young Douglas-fir, 100% 7-15
site occupied
Older Douglas-fir >40
Understory, first
application13
Understory, reapplications
200
100
200
200
100
280
200
260
100
150
300
200
250
100
45
100
Sources: Stone (1968) for irrigated wastewater sites; Henry (see
footnote 1) for western sludge application.
a Short-term rotation with harvesting at 4 to 5 years; represents first
growth cycle from planted seedlings.
b Adjust by % site covered.
gions of the United States. The reported average annual
N uptakes vary from 106 to 300 kg/ha/year (89 to 267
Ib/ac/year), depending on species, age, etc. Note that all
of the trees listed in the table are at least 5 years old, and
that during initial stages of growth, tree seedlings will have
relatively lower N uptake rates than shown.
Calculation of sewage sludge application rates to supply
plant N requirements is somewhat more complicated
than for agricultural crops because the following nitro-
gen transformations need to be considered in addition
to N mineralization and ammonia volatilization from the
sewage sludge: (1) denitrification, (2) uptake by under-
story, and (3) soil immobilization for enhancement of
forest soil organic-N (ON) pools. Table 8-7 presents
ranges of values and suggested design values for nitro-
gen transformations and losses from sewage sludge
applied to forest environments. The discussion below
focuses on major aspects of nitrogen dynamics in forest
ecosystems.
8.8.2.1 Nitrogen Mineralization
Mineralization (transformation of organic N to NHjj) oc-
curs when the organics in sewage sludge decompose,
releasing NHjf. Typical values for N mineralization for the
first year can be quite variable, ranging from 10% to
50% or more. A recent study conducted on a number of
sewage sludges from Oregon found that N mineralization
Table 8-7. Ranges of Values and Suggested Design Values
for Nitrogen Transformations and Losses From
Sewage Sludge Applied to Forest Environments
(Henry, 1993)
Transformation/Loss Design Value
Range
Suggested
Nitrogen Mineralization
Anaerobically digested 20% - 65%
short detention 40%
long detention 20%
Lagooned 10%-20%
short detention 20%
long detention 10%
Composted 5% - 50%
mixed or with short detention 40%
long detention, fully cured 10%
Ammonia Volatilization 0% - 25%
Open stand 10%
Closed stand 0%
Denitrification
Moist soils much of year 10%
Dry soils 0%
Soil Immobilization 0 - 1,000 Ib/ac
First application
young stand 100 Ib/ac
old stand 0 Ib/ac
Reapplications 0 Ib/ac
Plant Uptake (see Table 8-6)
101
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ranged from 20% to 65% for anaerobically digested
sewage sludge, 15% to 19% for lagooned sewage
sludge, and 36% to 50% for short-detention composted
sewage sludge for the first year.3 Table 8-7 gives ranges
and typical values for mineralization of sewage sludge
applied to forest sites. Because mineralization of differ-
ent sewage sludge varies so much, it is recommended
that mineralization studies be conducted on specific
sewage sludge.
8.8.2.2 Ammonia Volatilization
Volatilization losses (when NHJ; escapes to the atmos-
phere) from sewage sludge surface-applied to agricul-
tural soils have been measured from 10% to 60% of the
initial NHjf, and a typical design number is 50%. Forest
environments, however, probably lose considerably less
than this due to the low pH of the forest floor, the low
wind speed in forest stands, and less radiation reaching
the forest floor. Measurements taken both in western
and eastern Washington forests which were fairly open
range from 10% of the initial NHJ; being lost with a light
liquid application (dry site) (Henry and Zabowski, 1990),
25% in a western Washington forest with a closed can-
opy, and 35% lost in an open older forest stand in
western Washington.4 Current work in British Columbia
with surface applications to hybrid poplar plantations
suggests losses ranging from 25% to 100% of the initial
MM}.5 Suggested conservative values in Table 8-7 are
10% in open stands and no ammonia volatilization in
closed stands.
8.8.2.3 Denitrification
Excess MM} not taken up by the vegetation or immobi-
lized by the soil will in most cases microbially transform
into nitrate. When there is little oxygen in the soil, some
of the NO§ can be lost to the atmosphere as N2 or N2O,
a process called denitrification. Depending on soil con-
ditions, denitrification losses up to 25 percent of the total
can occur (U.S. EPA, 1983). Measurements taken in a
dry eastern Washington forest showed no denitrification
(Henry and Zabowski, 1990), while in a well drained
western forest about 10% denitrification was predicted
(Coles et al., 1992). Table 8-7 contains suggested val-
ues for denitrification.
8.8.2.4 Soil Immobilization Rates
Immobilization is the transformation of NHJ; into organic-
N by soil microbes. Because forest soils include an
organic layer containing decaying litterfall, twigs, and
Henry, C., A. Haub, and R. Harrison. Mineralization of sewage
sludge nitrogen from six Oregon cities. Draft report.
4 See footnote 1.
5Van Ham, M., and C. Henry. 1995. Personal communication be-
tween M. Van Ham and C. Henry, Pack Forest Research Center,
University of Washington, Eatonville, WA.
branches, the soil may have a lot of excess organic
carbon both in the forest floor and the surface soil
horizons. When this carbon decomposes, it uses some
of the available N. This immobilization represents long-
term soil storage of nitrogen that will be re-released (min-
eralized) at a very slow rate. Depending on the amount of
carbon and whether the site has been fertilized before,
immobilization can be up to 1,100 kg/ha (Henry, 1991). A
young stand with a good forest floor, however, probably
will immobilize in the neighborhood of 220 kg/ha.
When sewage sludge is re-applied, little additional N will
be immobilized unless the previous application was
made many years before. Table 8-7 contains suggested
values for immobilization. Overestimation of N immobi-
lization at forest sites can result in sewage sludge appli-
cation rates that significantly exceed tree N requirements.
Consequently, estimates of immobilization should either
be set very conservatively or based on sewage sludge
field studies that document the increase of soil organic-
N from different horizons.
The carbon to nitrogen ratios (C:N) of the forest floor and
surface soil horizons can serve as indicators of the
potential for soil immobilization of N from sewage sludge
applied to forest sites (excluding large woody debris that
decompose slowly). Generally, when the C:N ratio is
greater than 20-30:1, immobilization will occur. Woody
materials generally have much higher ratios (often ex-
ceeding 70:1). When sewage sludge is applied, the
available N allows microbial populations to expand rap-
idly and decomposes the soil organic matter, temporarily
locking up the N in microbial biomass or in long-term
stable humic acids. The N incorporated into the cell
structure of the microorganisms can eventually be re-
leased gradually as they die off.
8.8.2.5 Nitrogen Leaching
Typically, N is the limiting constituent for land applica-
tions of sewage sludge because when excess N is
applied, it often results in nitrate leaching. The N avail-
able from sewage sludge addition can be microbially
transformed into NOs through a process known as nitri-
fication. Because NO§ is negatively charged, it easily
leaches to the ground water with percolating rainfall. A
number of studies conducted at the University of Wash-
ington's Pack Forest Research Center confirmed that
heavy applications of N resulted in substantial increases
of NO§ in the ground water (Riekirk and Cole, 1976; Vogt
etal., 1980).6'7
Henry, C., R. King, and R. Harrison. Distribution of nitrate leaching
from application of municipal biosolids to Douglas-fir. Draft report.
7 Henry, C., and D. Cole. Nitrate leaching from fertilization of three
Douglas-fir stands with municipal biosolids. Draft report.
102
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8.8.2.6 Effects of Temperature on Nitrogen
Dynamics
In northern climates where winter soil temperatures are
low, transformations caused by microbial action in soil
slow down considerably. For instance, when the soil
temperature decreases about 18°F, microbial action is
about half as fast. At about 40°F microbial action essen-
tially stops. Through much of the winter the average
temperature of the soil may be at or below 40°F under
forest stands in northern parts of the United States. This
means that mineralization, nitrification, and denitrifica-
tion essentially stop. Thus, the nutrients from land appli-
cation of sewage sludge made during the winter will
essentially be stored in the forest floor and soil layers
until temperatures increase. Thus, NO§ leaching will not
significantly occur from winter applications because
NO§ will not be formed.
8.8.3 Calculation Based on Nitrogen for a
Given Year
The calculation for the application rate at forest sites
based on N for a given year involves determining site N
requirements and available N in the sewage sludge. A
site's net N needs are the sum of the N uptake by trees
and understory and soil immobilization of N:
Nreq = Utr + UUs + SI
(8-1)
where:
Nreq
Utr
Uus
SI
N requirements to be supplied by a given
application of sewage sludge, kg/ha
N uptake, by trees, kg/ha (Table 8-6)
N uptake by understory, kg/ha (Table 8-6)
N immobilization in soil from initial sew-
age sludge application, kg/ha (Table 8-7)
The requirements for N are met by: 1) the N mineralized
from previous applications, and 2) the N supplied by the
current application of sewage sludge (NHjf, NO§ and
mineralized ON). Organic-N is converted to NHJ; rela-
tively rapidly during the first year. In future years, the
remaining organic matter becomes more and more re-
calcitrant (does not decompose as easily) and ON min-
eralization is much reduced. Without local data on
mineralization rates, it is recommended that ON miner-
alization be ignored beyond three years after applica-
tion. The N supplied from previous applications is
calculated as shown in equation 8-2.
N
prev
where:
Nprev
{(Si)(ONi)(1-Ko)(Ki)
(S2)(ON2)(1-Ko)(1-Ki)(K2)
(S3)(ON3)(1-Ko)(1-Ki)(1-K2)(K3)}1 ,000
(8-2)
Si,2,etc. = Sewage sludge application rate 1, 2,
etc. years ago, t/ha
ONi,2,etc. = Percent N in sewage sludge 1, 2, etc.
years ago, expressed as a fraction
Ki,2,etc. = Mineralization rate of ON 1, 2, etc.
years after the year of application, ex-
pressed as a fraction
The amount of N available the year of application from
a ton of the sewage sludge (PAN) is calculated from
equation 8-3.
PAN = {(AN)(1-V) + NN + (ONo)(Ko)}(1-D)(10) (8-3)
where:
PAN = Total plant available nitrogen, kg/ton
AN = Percent NH^-N in sewage sludge as ap-
plied, %
NN = Percent NO§-N in sewage sludge as ap-
plied, %
ONo = Percent ON in sewage sludge as applied, %
Ko = Mineralization rate of ON during the year
of application, expressed as a fraction
V = Loss of ammonia by volatilization, ex-
pressed as a fraction
D = Loss of N by denitrification, expressed
as a fraction
The sewage sludge application rate to supply a given
year's N requirement is then calculated from the pre-
vious two equations:
So = (Nreq - Nprev)/PAN
(8-4)
Table 8-8 provides some example calculations for a young
plantation and older stand of Douglas-fir. In comparing
Table 8-8. Example First-year Application Rate for Sewage
Sludge Based on Available Nitrogen for Two
Different Types of Douglas-fir Stands
Total mineralized N from sewage sludge
applications in previous years, kg/ha
Assumptions
Uptake by trees, Utr (kg/ha)
Uptake by understory, Uus (kg/ha)
Soil immobilization, SI (kg/ha)
N required, Nreq (kg/ha) (Eq. 8-1)
N mineralization, previous sewage sludge
app., Nprev (kg/ha) (Eq. 8-2; no
previous application)
Initial ammonia-N, AN (%)
Initial nitrate-N, NN (%)
Initial organic-N, ON (%)
Fraction of ON mineralized, Kg (g/g)
Fraction of ammonia volatilized, V (g/g)
Fraction of N lost to denitrification, D (g/g)
Plant available N, PAN (kg/t) (Eq. 8-3)
Sewage sludge application rate,
S0 (t/ha) (Eq. 8-4)
Young
Stand
112
101
224
437
0
1.0
0.0
4.0
.25
.25
.25
17.5
33.3
Older
Stand
50
28
56
134
0
1.0
0.0
4.0
.25
.10
.10
19.0
7.8
103
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these cases, note that total N requirements are higher
for the young stand than the older stand (390 Ib/ac vs
120 Ib/ac), and available N in the sewage sludge is lower
in the younger stand due to higher losses from volatili-
zation and denitrification (26.3 Ib/ac vs 34.2 Ib/ac for the
older stand). Consequently there is a large difference in
sewage sludge application rates to meet N requirements
in the two stands: 14.8 T/ac for the younger stand and
3.5 T/ac for the older stand.
8.8.4 Calculation of Sewage Sludge
Application Rates for First and
Subsequent Years
The sewage sludge application rate in any given year
involves N budget calculations using procedures de-
scribed in Section 8.8.3 so as not to exceed site N
uptake requirements. Although the basic approach is the
same for any year's application, special considerations
in performing the N budget analysis will vary somewhat
depending on whether it is an initial application, and
whether subsequent applications are done annually or
periodically (i.e., intervals exceeding one year).
A key consideration in the N budget for an initial appli-
cation is determination of the amount of N in the sewage
sludge that will be immobilized by the soil (SI in Equation
8-1). Sewage sludge additions will build up the soil N
pools to the point that an equilibrium will eventually exist
between soil N mineralization and immobilization. Thus,
for subsequent annual applications, it should be as-
sumed that there will be no additional soil immobi-
lization. In fact, unless site-specific data documenting its
existence is available, it is prudent to assume no addi-
tional soil immobilization unless the last application was
made a considerable time in the past (>5-10 years).
The main difference between periodic applications com-
pared to annual applications is that cumulative applica-
tions over the same time period will be lower because
the N available from mineralization of previous sewage
sludge applications will generally be less than the po-
tential N uptake by trees in the years when sewage
sludge is not applied. This means that more total forest
acreage will generally be required for utilization of a
given amount of sewage sludge compared to annual
applications.
8.8.5 Calculation Based on Part 503
Pollutant Limits for Metals
The same Part 503 pollutant limits for metals that pertain
to sewage sludge application at agricultural sites, as
discussed in Chapter 7, also apply to forest sites (see
Chapter 3 for a discussion of pollutant limits).
8.9 Design Example of Sewage Sludge
Application at Forest Sites
This design example was developed in part to demon-
strate the procedures needed to ensure protection of
drinking water aquifers during an annual sewage sludge
land application program. The criteria used for an annual
sewage sludge land application project at a forest site are:
1. Nitrogen applications cannot exceed the ability of the
forest plants to utilize the N applied, with appropriate
adjustments for losses.
2. Cumulative metal loading limits cannot exceed the
cumulative pollutant loading rates (CPLRs), if applicable
(see Chapter 3), in the Part 503 rule.
8.9.1 Sewage Sludge Quantity and Quality
Assumptions
The sewage sludge generated by the hypothetical com-
munity in this design example is assumed to have the
following average characteristics:
• Anaerobically digested sewage sludge is generated
on the average of 18.2 t/day (20 T/day), dry weight,
by an activated sludge sewage treatment plant.
• Liquid sewage sludge averages 4 percent solids by
weight; its volume is 445,600 L/day (117,600 gal/day).
• Average sewage sludge analysis on a dry weight basis
is the same as the design example for agricultural ap-
plications (see Chapter 7 for metals concentrations):
- Organic-N (ON) = 2.5 percent by weight.
- Ammonia-N (AN) = 1 percent by weight.
- Nitrate-N (NN) = none.
8.9.2 Site Selection
The hypothetical community for this design example is
located in the Pacific Northwest. A large commercial
forest is located 24 km (15 mi) from the sewage treat-
ment plant. The site owner believes that he can expect
a significant increase in tree growth rate resulting from
the nutrients in sewage sludge. Preliminary investiga-
tions of the owner's property show that a total of 3,000 ha
(7,400 ac) are available, of which 1,200 ha (3,000 ac) have
the following desirable characteristics:
• Convenient vehicle access to public and private
roads, plus an in-place network of logging roads
within the area.
• No surface waters used for drinking or recreational
purposes are located within the area. Intermittent
stream locations are mapped, and 90-m (290-ft) (or
greater) buffer zones can be readily established
around the stream beds.
104
-------
• Ground water under one portion of the site has the
potential to serve as a drinking water aquifer.
• Public access is limited by signs and fences adjacent
to public roads.
• Topography is satisfactory, in that the area consists
largely of slopes less than 6 percent, and slopes
steeper than 30 percent can be readily excluded from
the sewage sludge application program.
• There are no residential dwelling units within the area.
• The area is roughly equally divided between young
hybrid poplar that is harvested on a 5-year rotation
and an established stand of Douglas-fir. However, the
1,200 ha (3,000 ac) area contains 200 ha (500 ac)
that either contain tree species that are incompatible
with sewage sludge applications (e.g., they fix nitro-
gen) or have slopes exceeding 30%. These areas are
excluded.
Table 8-9.
Year
N Requirements for Sewage Sludge Application to
Hybrid Poplar and Established Douglas-fir
Plantations
N,,
kg/ha
N,,
SI
N
req
Hybrid poplar
1995
1996
1997
1998
1999
Douglas-fir
1995
1996
1997
1998
1999
50
100
150
200
250
100
100
100
100
100
100
50
0
0
0
100
0
0
0
0
100
0
0
0
0
150
0
0
0
0
250
150
150
200
250
350
100
100
100
100
8.9.2.1 Soil and Hydrological Properties of the Site
The soils are of two types: glacial outwash, and residual
soil developed from andesitic bedrock. The glacial out-
wash is located largely on terraces with slopes less than
10 percent. Infiltration is rapid. The soil pH ranges be-
tween 5.5 and 6.0, and CEC is 14 meq/100 g. A2.5-cm
to 5.0-cm (1-in to 2-in) litter layer exists in the estab-
lished forest. The ground water table is approximately 9 m
(30 ft) below the soil surface. Residual soil is found on
slopes ranging up to 40 percent. Slopes steeper than 30
percent were eliminated from further consideration.
8.9.3 Determining the Sewage Sludge
Application Rate Based on Nitrogen
For this design example, assume that the sewage
sludge is to be land applied on an annual basis, and that
the quantity of sewage sludge applied is limited by N.
The purpose of the calculation is to have the plant-available
N in the applied sewage sludge equal the N uptake of the
trees and understory, accounting for assumed atmos-
pheric losses discussed in Section 8.8.3. This is a con-
servative approach intended to prevent leaching of
nitrate to the ground water aquifer.
Step 1. Calculate Net N Requirements for First 5
Years
N requirements for the hybrid poplar and the Douglas-fir
stands are calculated separately for the first 5 years
using Equation 8-1. Table 8-9 summarizes the assump-
tions used to calculate net N requirements. For the
hybrid poplar tree, N uptake is assumed to gradually
increase, from 50 kg N/ha in the first year to 250 kg N/ha
in the fifth year. Uptake of the understory is 100 kg N/ha
in the first year and 50 kg N/ha in the second year, and
is assumed to be negligible in subsequent years. The
amount of N immobilized as a result of decomposition
of soil organic carbon is assumed to be 100 kg/ha in the
first year and 0 in subsequent years. Table 8-9 shows a
high N need for the poplar of 250 kg/ha in the first year,
which drops to 100 kg/ha in the second year, and gradu-
ally increases back to 250 kg/ha by the fifth year.
Initial N required for the Douglas-fir stand is higher than
for the hybrid poplar (350 kg/ha) because of higher initial
N uptake by trees (100 kg/ha) and higher N immobi-
lization (150 kg/ha) because of higher initial litter/soil
organic carbon content. Understory uptake in the first
year was assumed to be the same as for the hybrid
poplar (100 kg/ha). In subsequent years, N uptake by
trees is assumed to remain steady at 100 kg/ha,
whereas N uptake by the understory and immobilization
is assumed to be negligible. The net effect of these
assumptions is that the N needs for the Douglas-fir
stand in the second through fifth years remain steady at
100 kg/ha, as shown in Table 8-9.
Step 2. Calculate Initial Available N in Sewage
Sludge for Each Year
Available N in the sewage sludge needs to be calculated
for each forest stand type, and recalculated for any year
in which changing site conditions may affect N availabil-
ity. In the first two years surface application is made to
a very open stand where both heat and wind reach the
soil surface, thus volatilization can be high (assumed to
be 0.5), but since the soils are well drained, denitrifica-
tion is low (assumed to be 0.1). Mineralization rate for
this first year is taken from Table 7-7 in Chapter 7 in the
column for anaerobically treated sewage sludge. N
availability from sewage sludge applied to the hybrid
poplar plantation for the first year is calculated using
Equation 8-3 as follows:
105
-------
PANi,2 = {(AN)(1-V) + NN
= {(1.0)(1-0.5) + 0
= 9.0 kg/t
(ONo)(K0)}(1-D)(10)
(2. 5)(0.20)}(1-0.1)(10)
Table 8-10. Sewage Sludge Application Rates to Meet N
Requirements at Forest Sites
During the following years, the trees reduce both radia-
tion and wind reaching the soil surface, so ammonia
volatilization is assumed to be reduced to 0.25, while
denitrification remains relatively constant at 0.1.
PANs-5=
NN
+ 0
(ON0)(K0)}(1-D)(10)
(2.5)(0.20)}(1 -
= 11.3 kg/t
Available N from sewage sludge applied to the Douglas-
fir stand will be 1 1 .3 kg/t for all 5 years because the wind
and heat reaching the forest floor are presumed to be very
similar to the third year conditions in the poplar stand.
Step 3. Calculate First-Year Sewage Sludge
Application Rate
First-year sewage sludge application rates to forest sites
can be substantially higher than in subsequent years
because of the initial response of understory growth,
which increases N uptake, and immobilization of N, as
discussed in Section 8.8.2; no mineralization of ON from
previous applications occurs. The initial sewage sludge
application rate is calculated using Equation 8-4:
SO = (Nreq - Nprev)/PAN
= (250 - 0)/9.0
= 28 t/ha(for the hybrid poplar)
= (350 - 0)/11.3
= 31 t/ha(for the Douglas-fir)
Step 4. Calculate Sewage Sludge Application Rates
for Subsequent Years
Sewage sludge application rates for subsequent years
must take into account mineralization of organic N from
previous sewage sludge applications. Table 8-10 shows
the results of mineralization calculations for the second
through fifth years. In this example, the second-year
sewage sludge application rate to supply N require-
ments of the hybrid poplars drops from 27.8 t/ha to 12
Year
t/ha
Hybrid poplar
1995
1996
1997
1998
1999
Douglas-fir
1995
1996
1997
1998
1999
Nreq
250
150
150
200
250
350
100
100
100
100
N
i>"prev
0
42
32
35
33
0
46
23
27
15
PAN
9
9
11.3
11.3
11.3
11.3
11.3
11.3
11.3
11.3
S
S0 (cumulative)
27.8
12.0
10.4
14.6
19.2
31.0
4.7
6.8
6.4
7.5
28
40
50
65
84
31
36
43
49
56
Notes:
Nreq = N requirements to be supplied by a given application of
sewage sludge, kg/ha
Nprev = Total mineralized N from sewage sludge applications in
previous years, kg/ha
PAN = Total plant nitrogen, kg/ton
SQ = Sewage sludge application rate for a given year
S = Sewage sludge application (cumulative)
t/ha and then gradually increases to 19.2 t/ha in the fifth
year. The Douglas-fir stand shows an even more dra-
matic drop from 31 t/ha in the first year to 4.7 t/ha in the
second year. The third year application rate for Douglas-fir
increases to 6.8 t/ha, with slight additional increases to 6.4
and 7.5 t/ha for the fourth and fifth years, respectively.
8.9.4 Site Capacity Based on Nitrogen
The design example site has 1,000 ha (2,471 ac) suit-
able for sewage sludge application, which is roughly
equally divided between established Douglas-fir forest
and the hybrid poplar plantation (assume 500 ha [1,235
ac] of each). The quantity of sewage sludge that can be
applied during the first 5 years is summarized in Table
8-11. Total application in the first year could be as high as
29,400 t. In the second year this drops to 8,400 t, and
gradually increases to 13,3001 by the fifth year.
Table 8-11. Maximum Annual Sewage Sludge Application Based on N Requirements
Year
1995
1996
1997
1998
1999
Area
(ha)
500
500
500
500
500
Hybrid
(t/ha)
27.8
12.0
10.4
14.6
19.2
Poplar
(t)
13,900
6,000
5,200
7,300
9,600
(t/ha)
31.0
4.7
6.8
6.4
7.5
Douglas Fir
(t)
15,500
2,400
3,400
3,200
3,700
Total
(t)
29,400
8,400
8,600
10,200
13,300
t = metric tonnes.
106
-------
Since the community generates 18.2 t/day (20 T/day),
dry weight of sewage sludge, or 6,643 t/year (7,307
T/year), this would supply sewage sludge applied at the
first year design rate of only one-fourth of the site. This
scenario also requires less than the entire site for reap-
plication (at the lesser rates of years 2-5). Therefore, the
hypothetical site appears to be of quite sufficient area.
However, careful planning and record keeping will be
required to schedule the amount and location of sewage
sludge applications to maintain a good program.
8.10 References
Coles, J., C. Henry, and R. Harrison. 1992. Gaseous nitrogen losses
from three Douglas-fir stands after reapplication of municipal
sludge. Agron. Abstr. American Society of Agronomy, Madison, Wl.
Dyck, W., S. Gower, R. Chapman-King, and D. van der Wai, 1984.
Accumulation in aboveground biomass of Douglas-fir treated with
municipal sewage sludge. (Draft Report.)
Henry, C. 1991. Nitrogen dynamics of pulp and paper sludge to forest
soils. Water Sci. Tech. 24(3/4):417-425.
Henry, C., D. Cole, T. Hinckley, and R. Harrison. 1993. The use of
municipal and pulp and paper sludges to increase production in
forestry. J. Sus. For. 1:41-55.
Henry, C., and R. Harrison. 1991. Literature reviews on environmental
effects of sludge management: Trace metals, effects on wildlife
and domestic animals, incinerator emissions and ash, nitrogen,
pathogens, and trace synthetic organics. Regional Sludge Man-
agement Committee. University of Washington, Eatonville, WA.
Henry, C., and D. Zabowski. 1990. Nitrogen fertilization of Ponderosa
pine: I. Gaseous losses of nitrogen. Agron. Abstr., American So-
ciety of Agronomy, Madison, Wl.
Riekirk, H., and D. Cole. 1976. Chemistry of soil and ground water
solutions associated with sludge applications. In: Edmonds, R.,
and D. Cole, eds. Use of dewatered sludge, as an amendment
for forest growth, Vol. I. Center for Ecosystem Studies, College of
Forest Resources, University of Washington, Eatonville, WA.
Sopper, W. 1993. Municipal sludge use in land reclamation. Boca
Raton, FL: Lewis Publishers.
Stone, E.L. 1968. Microelement nutrition of forest trees: A review. In:
Forest fertilization—Theory and practice. Tennessee Valley
Authority, Muscle Shoals, Al. pp. 132-175.
U.S. EPA. 1984. Environmental regulations and technology: Use and
disposal of municipal wastewater sludge. EPA/625/10-84/003.
Washington, DC.
U.S. EPA. 1983. Process design manual: Land application of munici-
pal sludge. EPA/625/1-83/016.
Vogt, K., R. Edmonds, and D. Vogt. 1980. Regulation of nitrate levels
in sludge, soil and ground water. In: Edmonds, R., and D. Cole,
eds. Use of dewatered sludge as an amendment for forest growth,
Vol. III. Institute for Forest Resources, University Washington, Ea-
tonville, WA.
107
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Chapter 9
Process Design for Land Application at Reclamation Sites
9.1 General
This chapter presents design information for application
of sewage sludge to reclamation sites.1 It is assumed
that the preliminary planning discussed in earlier chap-
ters has been done, that a sewage sludge transportation
system has been selected, and that reclamation sites
are potentially available within a reasonable distance
from the treatment works. Primary emphasis is on the
revegetation of the reclamation site with grasses and/or
trees. If future land use for agricultural production is
planned, the reader should also refer to Chapter 7,
"Process Design for Agricultural Land Application Sites."
Extensive areas of disturbed land that can benefit from
reclamation exist throughout the United States as a
result of mining for clay, gravel, sand, stone, phosphate,
coal, and other minerals. Also fairly widespread are
construction areas (e.g., roadway cuts, borrow pits) and
areas where dredge spoils or fly ash have been depos-
ited (Sopper and Kerr, 1982). Other areas needing rec-
lamation include clear-cut and burned forests, shifting
sand dunes, landfills, and sites devastated by toxic
fumes. Some disturbed mining sites may be designated
as "Superfund" sites, and applicable regulations may
pertain.
Disturbed land can result from both surface and under-
ground mining operations, as well as the deposition of
ore processing wastes. The Soil Conservation Service
reported that as of July 1, 1977, the minerals industry
had disturbed a total of 2.3 mil ha (5.7 mil ac), of which
about 50 percent was associated with surface mining
(U.S. Soil Conservation Service, 1977). Only about one-
third of the disturbed areas was reported to have been
reclaimed. Table 9-1 presents the amount of hectares
under permit for surface, underground, and other mining
operations during the period 1977 to 1986. Table 9-2
presents the number of hectares that have been re-
claimed with bonds released during 1977 to 1986—about
40 percent of the land under permit (Sopper, 1993).
Most disturbed lands are difficult to revegetate. These
sites generally provide a harsh environment for seed
Table 9-1. Hectares Under Permit for Surface, Underground,
and Other Mining Operations From 1977 to 1986a
(Sopper, 1993)
Year
Total Hectares
1978
1979
1980
1981
1982
1983
1984
1985
1986
Total
68,635
146,002
1 41 ,842
153,880
136,568
182,896
265,768
175,057
107,429
1 ,378,077
' States and Indian tribe lands included in above tabulations were Ala-
bama, Alaska, Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky,
Louisiana, Maryland, Missouri, Montana, New Mexico, North Dakota,
Ohio, Pennsylvania, Tennessee, Texas, Utah, Virginia, Washington,
West Virginia, Wyoming, Crow Tribe, Hopi Tribe, Navajo Tribe.
Table 9-2. Number of Hectares Reclaimed With Bonds Released
During 1977 to 1986a (Sopper, 1993)
Year
Total Hectares
1978
1979
1980
1981
1982
1983
1984
1985
1986
Total
19,078
42,580
51,401
52,547
80,351
69,874
96,910
81,696
68,280
562,717
40 CFR Part 503 defines a reclamation site as drastically disturbed
land that is reclaimed using sewage sludge (see Chapter 3).
States and Indian tribe lands included in above tabulations were Ala-
bama, Alaska, Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky,
Louisiana, Maryland, Missouri, Montana, New Mexico, North Dakota,
Ohio, Pennsylvania, Tennessee, Texas, Utah, Virginia, Washington,
West Virginia, Wyoming, Crow Tribe, Hopi Tribe, Navajo Tribe.
109
-------
germination and subsequent plant growth. Major soil
problems may include a lack of nutrients and organic
matter, low pH, low water-holding capacity, low rates of
water infiltration and permeability, poor physical proper-
ties, and the presence of toxic levels of trace metals. To
correct these conditions, large applications of lime and
fertilizer may be required, and organic soil amendments
and/or mulches also may be necessary.
Pilot- and full-scale demonstration projects have shown
that properly managed sewage sludge application is a
feasible method of reclaiming disturbed land and can
provide a cost-effective option for sewage sludge use.
According to the 1990 NSSS, 65,800 dry metric tons per
year (1.2 percent of the sewage sludge used or dis-
posed of annually) are used for land reclamation (58 FR
9257). Table 9-3 lists some of the more significant land
reclamation projects using sewage sludge during the
past 20 years. Research has shown that good plant
cover can be established on many types of disturbed
lands using sewage sludge, which is superior to inor-
ganic fertilizer for such uses (Sopper, 1993). Sewage
sludge has been found to have a beneficial effect on the
establishment and growth of grass and legume species
on mine land (Sopper, 1993). In addition, the pH buffer-
ing capacity of sewage sludge makes it beneficial in the
reclamation of acidic sites (Gschwind and Pietz, 1992).
At reclamation sites, sewage sludge application usually
is performed once. The sewage sludge is not applied
again to the same land area at periodic intervals in the
future, as is the case at agricultural and forest sites.
Thus, most reclamation projects must have a continu-
ous supply of new disturbed land on which to apply
sewage sludge in future years. This additional disturbed
land may be created by ongoing mining or mineral proc-
essing operations or may consist of presently existing
large areas of disturbed land which are gradually re-
claimed. In either case, an arrangement is necessary
with the land owner to allow for future sewage sludge
land application throughout the life of the sewage sludge
land application project.
9.2 Consideration of Post-Sewage
Sludge Application Land Use
If land application of sewage sludge is used in the
reclamation process, it is important to consider federal
and state mining regulations concerning revegetation
(e.g., 30 CFR Parts 816 and 817) and the federal Sur-
face Mining Control and Reclamation Act (Public Law
95-87, Section 515) (U.S. Department of Interior, 1979;
Federal Register, 1982) and its amendments (54 FR 23).
Regulations established under this Act require that a
diverse, effective, and permanent vegetative cover of
the seasonal variety native to the affected land must be
established and must be capable of self-regeneration
and plant succession equal in coverage to the natural
vegetation of the area (Federal Register, 1982). Before
beginning a land application project using sewage
sludge at a reclamation site, the final use of the site after
it has been reclaimed must be considered regarding
compliance with these regulations. If the post-mining
land use is to be agricultural production or animal graz-
ing, agricultural land application requirements for sew-
age sludge must be followed, such as the federal Part
503 regulation and any applicable state regulations. If
the site is to be vegetated primarily for erosion control,
a single large application of sewage sludge is desirable
for rapid establishment of the vegetative cover. Gener-
ally, Part 503 requirements for agricultural, forest, and
reclamation sites are the same (see Chapter 3). As
discussed in Section 9.3.1.1, the Part 503 regulation
specifies that for land reclamation, the permitting author-
ity can authorize a variance from the agronomic rate
requirement for sewage sludge application.
In humid regions, a majority of the reclaimed mine areas
have been planted to forests. Some of these areas are
managed for lumber or pulp production, while others are
allowed to follow natural succession patterns. If the re-
claimed area is to be turned into forest land, larger sewage
sludge application rates can be considered than those
used for agricultural crops, since the products from the
forest are generally not a factor in the human food chain.
In all cases, post-mining land use must be considered prior
to the use of sewage sludge in land reclamation.
9.2.1 Mining Regulations
Prior to mining, a plan must be submitted to the appro-
priate agency stating the method of reclamation and
post-mining land use. Amended regulations under the
Surface Mining Control and Reclamation Act issued in
1982 and 1988 set forth the following requirements:
• The permanent vegetative cover of the area must be
at least equal in extent of cover to the natural vege-
tation of the area and must achieve productivity levels
comparable to unmined lands for the approved post-
mining land use. Both native and introduced species
may be used.
• The period of responsibility begins after the last year
of augmented seeding, fertilization, irrigation, or other
work that ensures revegetation success.
• In areas of more than 26 inches of average annual
precipitation, the period of extended responsibility will
continue for not less than 5 years. In areas with 26
inches of precipitation or less, the period of respon-
sibility will continue for not less than 10 years.
• Normal husbandry practices essential for plant estab-
lishment would be permitted during the period of re-
sponsibility so long as they can reasonably be
expected to continue after bond release.
110
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Table 9-3. Recent Land Reclamation Projects With Municipal Sludge (Adapted From Sopper, 1993)
Sludge
Type of Disturbed Land
Acid strip mine spoil
Deep mine anthracite refuse
Acid strip mine spoil
Top-soil strip mine spoil (49 sites)
Zinc smelter site
Acid strip mine spoil
Abandoned Pyrite mine
Sandstone and siltstone mine soil
Non acid-forming overburden
Borrow pit
Acid strip mine spoil
Overburden minesoil
Iron ore tailings
Taconite tailings
Copper mine spoil
Copper mine
Borrow pit
Kaolin spoil
Marginal land
Acid stripmine spoil
Acid stripmine spoil
Reconstructed prime farmland
C and D canal dredge material
C and D canal dredge material
State
PA
PA
PA
PA
PA
VA
VA
VA
SC
WV
WV
Wl
Wl
CO
TN
GA
IL
KY
KY
MD
DE
Type3
Dig.-D + effluent
Dig.-D
Dig.-D, C
Dig.-D
Dig.-D, C/C
Dig.-D
Dig.-D
Dig.-D, C
Dig-D
Dig.-D, C
Dig.-D
Dig.-D
Dig.-D
Dig.-D
Dig.-D
Dig.-L
(Nl)
Dig.-D
Dig.-D
Dig.-D
Application Rates
(mg/ha)
5-20 cm
0, 40-150
134
47
120-134
82-260
22, 56, 112, 224
112
0, 17, 34, 68
Various (Nl)
0, 22.4, 44.8, 78.4
42-85
28-115
0, 30, 60
0, 34, 69, 275
0, 31-121
28-96
0, 22.4, 448
112
100
Plant/Animal Studied
Ryegrass
Hybrid poplar
1 0 tree spp.
5 Grass spp.
5 Legume spp.
Tall fescue
Orchard grass
Birdsfoot trefoil
Ryegrass
5 Grass species
5 Legume species
11 Tree species
Microorganisms
Tall fescue Lespedeza
Weeping lovegrass
Wheat, rye, oats
Tall fescue
Hay/pasture seed mix
Tall fescue
Sweetgum
Blueberries
Red clover
Tall fescue
Orchardgrass
Birdsfoot trefoil
5 Native prairie grasses
4 Prairie forbes
Foxtail
4 Grass-legume mixtures
Fourwing saltbush
Mountain big sagebrush
Pine species
Sweetgum
Tall fescue
Weeping lovegrass
European alder
Blacklocust
Cottonwood
Loblolly pine
Northern red oak
Grain sorgham
Corn
KY bluegrass
Tall fescue
Red fescue
Weeping lovegrass
Tall fescue
Red fescue
KY bluegrass
Parameters
Tested13
WA
GR
PA
SA
WA
GR
PA
SA
WA
GR
PA
SA
SO.SA
GR
PA
SA
WA
GR
SA.PA
SA
GR
PA
GR
PA
SA.PA
GR
GR
GR
GR.PA.SA
GR.SA
GR
WA
GR
PA
SA
GR
PA.SA
PA
SA
WA
PA
SA
111
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Table 9-3. (continued)
Type of Disturbed Land
Sludge
State
Type3
Application Rates
(mg/ha)
Plant/Animal Studied
Parameters
Tested13
Acid stripmine spoil OH Dig.-D
Degraded, Semiarid Grassland NM Dig.-D
11-716
0, 22.5, 45, 90
Tall fescue
Blue gamma
Galleta
Bottlebrush squirreltail
GR.PA
SA.WA
GR.PA.SA
Zn smelter surroundings
Lignite overburden
OK
TX
Dig.-L + effluent
Dig.-D
2.5-34 cm
56
10 grass spp.
1 legume
NA
GR
PA
SA
SA.WA
Dig. = digested, L = liquid, D = dewatered, C = composted, C/C = dewatered cake and compost mix, Nl = no information.
b GR = growth responses, PA = plant tissue analysis, SA = soil analysis, WA = water analysis, SO = soil organisms, PO = pathogenic organisms,
AH = animal health, NA = not applicable.
• In areas of more than 26 inches of precipitation, the
vegetative cover and production of pasture, grazing
land, and cropland shall be equal to or exceed the
success standard only during any 2 years except the
first year. Areas approved for other uses shall equal
or exceed success standards during the growing sea-
son of the last year of the responsibility period. In
areas with less than 26 inches of precipitation, the
vegetative cover must be equal to the success standard
for at least the last 2 years of the responsibility period.
• The ground cover, productivity, or tree stocking of the
revegetated area shall be considered equal to the
success standards approved by the regulatory authority
when they are not less than 90 percent of the success
standard with 90 percent statistical confidence.
Under the federal mining regulations, the potential post-
mining land use must be of a level equal to or higher
than the pre-mining land use. Typical land uses include:
• Wilderness or unimproved use.
• Limited agriculture or recreation with little develop-
ment, such as forest land, grazing, hunting, and fishing.
• Developed agriculture or recreation, such as crop
land, water sports, and vacation resorts.
• Suburban dwellings or light commercial and industry.
• Urban dwelling or heavy commercial and industry.
Many of these land uses are compatible with sewage
sludge application.
9.3 Nutrients, Soil pH, and Climate
Considerations
9.3.1 Nutrients
During mining and regrading operations, the original
surface layers are usually buried so deeply that the soil
nutrients present are not available to plants in the dis-
turbed soil. Nitrogen and phosphorus are often deficient
on disturbed lands, with phosphorus often being the
most limiting fertility factor in plant establishment. Sew-
age sludge is generally an excellent source of these
nutrients. The amount of sewage sludge applied at one
time during land reclamation can be relatively large (7
to 450 dry t/ha or 3 to 200 T/ac) to ensure that sufficient
nutrients, as well as organic matter, are introduced into
the soil to support vegetation until a self-sustaining eco-
system is established. The local agricultural experiment
station or Cooperative Extension Service can provide
recommendations for the additional quantities of N, P,
and K required to support vegetation for the site.
9.3.1.1 Nitrogen
An advantage of using sewage sludge for land reclama-
tion is that it is a slow-release source of organic nitrogen
fertilizer that will supply some nitrogen for 3 to 5 years.
Depending on the treatment process, much of the origi-
nal wastewater nitrogen is in the organic form and there-
fore not immediately available for plant use until it is
converted to inorganic nitrogen by mineralization, mak-
ing it available to plants. This process is discussed in
Chapters 4 and 7.
Under the federal Part 503 regulation, the permitting
authority may authorize for reclamation sites a sewage
sludge application rate greater than the agronomic rate
for N. The person who applies the sewage sludge must
be able to show that N application in excess of crop and
vegetative requirements would not contaminate ground
water or surface water. The permitting authority may
allow a temporary impact on the reclamation site (e.g., may
allow one application only, at a higher application rate).
The amount of nitrogen needed to establish vegetation
on a reclamation site depends on the type of vegetation
to be grown and the amount of nitrogen available in the
soil. The designer should have information on:
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• The amount and type of nitrogen in the sewage
sludge (organic N, ammonium, and nitrate).
• The plant-available nitrogen content of the existing
soil, if available.
• The fertilizer nitrogen requirements of the vegetation
planned for the site.
This information is used to determine the sewage sludge
application rate so that sufficient nitrogen is applied for
the vegetation but is not in excessive amounts that could
cause unacceptable levels of nitrate leaching into sur-
rounding ground water, as shown in Section 9-7.
The designer should also consider the postreclamation
land use when determining the amount of nitrogen needed
to supply the vegetative needs. If the vegetation grown is
to be harvested and removed from the site, supplemental
nitrogen applications may be needed periodically to main-
tain adequate productivity. If the reclaimed area is refor-
ested or the vegetation grown is not harvested, most of the
nitrogen will remain on the site and be recycled through
leaf fall and vegetation decomposition.
Sewage sludge applications on mine land usually increase
the total nitrogen concentration in the foliage of vegetation
(Sopper, 1993). It has been speculated that while exces-
sively high nitrogen concentrations in plants do not harm
the plants themselves, they could cause metabolic disrup-
tions in foraging animals. No published documentation of
this phenomenon exists, however (Sopper, 1993).
Drastically disturbed lands can be divided into two cate-
gories—those requiring topsoil enhancement and those
without topsoil. On sites with topsoil, an agricultural
application rate might be used, with relatively small
quantities of sewage sludge being applied annually (as
discussed in Chapter 7). On abandoned sites or sites
without topsoil replacement, however, a much larger
application of sewage sludge may be necessary to es-
tablish vegetation and improve the physical status of the
soil. Soil fertility is also increased by the nitrogen and
phosphorus in sewage sludge as well as the many micro-
nutrients in sewage sludge necessary for plant growth.
9.3.2 SoilpH andpHAdjustment
Most grasses and legumes, as well as many shrubs
and deciduous trees, grow best in the soil pH range
from 5.5 to 7.5, and pH adjustments may be necessary
at reclamation sites.
Several states have adopted regulations stating that where
sewage sludge is applied to land, the soil pH must be
adjusted to 6.0 or greater during the first year of initial
sewage sludge application and 6.5 during the second year
(Pennsylvania Department of Environmental Resources,
1988). In addition, the soil pH of 6.5 may need to be
maintained for 2 years after the final sewage sludge appli-
cation. This is recommended because trace metals are
more soluble under acidic conditions than neutral or
alkaline conditions. If the soil pH is not maintained above
6.0 and is allowed to revert to more acidic levels, some
trace metals in the sludge may become soluble; once in
solution, the metals would be available for plant uptake.
Lime often is used for pH adjustment, but other agents
also are feasible. Recommendations for pH adjustment
can usually be obtained by sending soil samples to a
qualified laboratory orthe agricultural experiment station
soil testing lab at the nearest land grant college or
university. Common soil tests for lime requirements
often seriously underestimate the lime requirement for
sulfide-containing disturbed lands. In addition, the appli-
cation of sewage sludge on disturbed lands may cause
further acidification. This must be taken into considera-
tion in calculating lime requirements.
9.3.3 Factors A ffecting Crop Yields at
Reclamation Sites
Where sewage sludge is applied at reclamation sites for
agricultural production, crop yields can be variable. Limit-
ing factors can include climatic conditions and shallow
rooting depths (Gschwind and Pietz, 1992). Peterson et al.
(1982) found that adequate moisture and essential ele-
ments for crop needs were critical for corn yields grown
immediately after land leveling on sewage sludge-
amended soil at a strip mine reclamation site. Pietz et al.
(1982) found that important parameters were shallow root-
ing depth, soluble salts, moisture stress, and element
interactions in plant tissue, sewage sludge, and soil.
9.3.4 Special Considerations for Arid Lands
When sewage sludge is land applied to reclamation
sites in arid climates, the concentration of soluble salts
in the sludge should be considered. Accumulation of
salts can hinder revegetation of native grasses because
of competition from salt-tolerant, early successional plants
(Jacobs et al., 1993). Other considerations for sewage
sludge application to arid lands are discussed in Chapter 7.
9.4 Vegetation Selection
9.4.1 General
Many plant species have been successfully established
at reclamation sites. Each site should be considered
unique, however, and plant species or seed mixtures to
be used should be carefully selected. Local authorities
should be consulted for recommendations of appropri-
ate species and varieties of plants as well as plant
establishment techniques. Revegetation suggestions
for various regions of the United States are presented
in Tables 9-4 through 9-14. Table 9-15 presents some
successful plant species and species mixtures used in
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Table 9-4. Humid Eastern Region Vegetation
Various grasses, legumes, trees, and shrubs have been evaluated for use on disturbed lands in the humid regions of the United
States. Grass species that have shown promise for use on low pH soils in the eastern United States include weeping lovegrass,
bermudagrass varieties, tall fescue, chewings fescue, switchgrass, red top, colonial bentgrass, creeping bentgrass, velvet bentgrass,
deertongue, big bluestem, little bluestem, and brown sedge bluestem (Bennett et al., 1978).
Some of the more agriculturally important grass species adapted to better soil conditions on disturbed sites include bromegrass,
timothy, orchardgrass, perinnial rye grass, Italian ryegrass, Kentucky bluegrass, Canadian bluegrass, Reed canarygrass, Dallisgrass,
bahiagrass, and in special situations, lawn grasses including Zoysia japonica Steud and Zoysia matrella. In addition to the common
grasses, several of the cereal grains, such as rye, oats, wheat, and barley have been used, but mainly as companion crops (Bennett
et al., 1978).
Legume species tested on disturbed sites in eastern United States include alfalfa, white clovers, crimson clover, birdsfoot trefoil,
lespedezas, red clover, crownvetch, and hairy vetch. Other species that have been successfully tested include flat pea, kura clover,
zigzag clover, sweet clover, and yellow sweet clover (Bennett et al., 1978).
Several grass and legume mixtures have been used successfully in Pennsylvania to revegetate drastically disturbed lands amended
with municipal sludges. The primary mixture and seeding rate used for spring and summer seeding is:
Species Amount kg/ha
Kentucky-31 tall fescue 22
Orchardgrass 22
Birdsfoot trefoil 11
Total 55
Metric conversion factor:
1 kg/ha = 0.89 Ib/ac.
For late summer and early fall seeding the following mixture has been used successfully:
Species Amount kg/ha
Kentucky-31 tall fescue 11
Orchardgrass 5
Winter rye (1 bu/ac) 63
Total 79
Metric conversion factor:
1 kg/ha = 0.89 Ib/ac.
This mixture has usually been sufficient to establish a vegetative cover to protect the site over the winter season. The following
spring, an additional seed mixture, consisting of orchardgrass (11 kg/ha; 9.8 Ib/ac) and birdsfoot trefoil (11 kg/ha; 9.8 Ib/ac), is
applied. Other seeding mixtures for spring, summer, and fall seeding are found in Rafaill and Vogel, 1978.
Several tree and shrub species have been utilized on disturbed land areas in the eastern United States. However, in general, trees
and shrubs have been planted either after the soil has been stabilized with herbaceous species, like grasses and legumes, or has
been planted with them. On certain drastically disturbed areas, trees may be the only logical choice of vegetation where a future
monetary return is expected. They do provide long-term cover and protection with little or no additional care and maintenance. The
same precautions should be exercised in selecting tree species for use on disturbed land sites as in selecting grasses and legumes.
The soil acidity, plant nutrient requirements, chemical and physical properties of the soil, site topographical influences, and other
environmental factors should be considered.
Common tree and shrub species grown successfully on disturbed land sites in the eastern United States include black locust,
European black alder, autumn olive, white pine, scotch pine, Virginia pine, short leaf pine, red pine, Norway spruce, European and
sewage sludge reclamation projects. Food crop selec- If the goal of the reclamation effort is to establish a
tion is discussed in Chapter 7. vegetative cover sufficient to prevent erosion, a peren-
nial grass and legume mixture is a good crop selection.
Plant species to be used should be selected for their It is important to select species that are not only corn-
ability to grow under drought conditions and their toler- patible, but also grow well when sewage sludge is used
ance for either acid or alkaline soil material. Salt toler- as the fertilizer. A combined grass and legume seeding
ance is also desirable. mixture allows the grass species to germinate quickly
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Table 9-5. Drier Mid-West and Western Region Vegetation
A large number of plant species have been tested on disturbed lands in the Intermountain Region of the United States (Berry, 1982).
Fewer species have been evaluated for reclamation use in the drier regions of the United States. The objective in many reclamation
plantings in the drier regions is to return the area to climax vegetation. In almost every instance, the soils are not the same as
before the disturbance occurred, and it would seem in many cases that species lower in the successional stage may be better
adapted and more easily established on these sites. Whether a single species or a mixture is selected depends on several factors,
including the planned future use of the site, the desire to have the planting blend with the surrounding vegetation, and the
adaptability and compatibility of the species selected. The factors limiting the successful establishment of vegetation on disturbed
areas may be different on a site being reclaimed than on adjacent undisturbed areas, where a plant species may be growing
together in what appears to be a stable community. Even after the species have been selected, the proportionate amounts of
seeding are not easily determined. The successful experiences of the past 40 years from seeding range mixtures and planting
critical areas appears to be the best guide to the opportunities for success of either single species or mixtures (Berg, 1978).
Table 9-6. Western Great Lakes Region
This region includes Wisconsin, eastern Minnesota, and the western upper peninsula of Michigan. The common grasses, generally
used in mixtures with a legume, are tall fescue, smooth brome, and timothy. Kentucky bluegrass and orchardgrass are also well
adapted. "Garrison" creeping foxtail and reed canarygrass perform well on wet sites. The most commonly used legumes are
birdsfoot trefoil and crownvetch. Numerous species of woody plants can be used depending on specific site conditions. Siberian
crabapple, several species of poplars, tatarian and Amur honeysuckles, silky dogwood, redosier dogwood, European black alder,
black cherry, and green ash perform well. Autumn olive is adapted to the southern portion of this area.
Table 9-7. Northern and Central Prairies
This is the region known as the Corn Belt. Grasses adapted to the area are Kentucky bluegrass, tall fescue, smooth brome, timothy,
and orchardgrass. Reed canarygrass is adapted to wet areas. Switchgrass, big bluestem, and Indiangrass are well adapted warm
season natives. Birdsfoot trefoil, crownvetch, and alfalfa are commonly used legumes.
Woody species that have been successful include autumnolive, European black alder, poplar species, tatarian honeysuckle, Amur
honeysuckle, black cherry, eastern red cedar, pines, oaks, black walnut, green ash, black locust, black haw, and osage-orange.
Table 9-8 Northern Great Plains
This region includes most of the Dakotas and Nebraska west to the foothills of the Rocky Mountains and includes northeastern
Colorado. The native wheatgrass (western, thickspike, bluebunch, streambank, and slender) are used extensively in seeding
mixtures. Western wheatgrass should be included in most mixtures, although for special purposes thickspike or streambank
wheatgrass are more appropriate. Green needlegrass is an important component of mixtures except in the drier areas. On favorable
sites big bluestem, little bluestem, and switchgrass provide opportunities for color or for a different season of use. Prairie sandreed is
adapted to sandy soils throughout the region. "Garrison" creeping foxtail and reed canarygrass are adapted to wet sites.
Crested wheatgrass has been used extensively and is long-lived in this climate. Intermediate and pubescent wheatgrasses are
useful in establishing pastures. The use of smooth brome and tass fescue is limited to the eastern portions of the Northern Great
Plains where the annual precipitation exceeds 50 cm (19.7 in). Alfalfa and white sweetclover are the only legumes used in most of
the area for reclamation plantings.
Many native and introduced woody plants are adapted for conservation plantings. Fallowing to provide additional moisture is required
for establishment of most woody plants and cultivation must generally be continued for satisfactory performance of all but a few
native shrubs. These practices may not be compatible with certain reclamation objectives, thereby limiting the use of woody species
to areas with favorable moisture situations. Some woody plants useful in this area, if moisture and management are provided, are
Russian-olive, green ash, skunkbush sumac, Siberian crabapple, Manchurian crabapple, silver buffaloberry, tatarian honeysuckle,
chokecherry, Siberian peashrub, Rocky Mountain juniper, and willow species.
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Table 9-9. Southern Great Plains
The Southern Great Plains are considered to be the area from southcentral Nebraska and southeastern Colorado to central Texas.
The most common native grasses of value in reclaiming drastically disturbed lands include big bluestem, little bluestem, Indiangrass,
switchgrass, buffalograss, blue grama, sideoats grama, and sand lovegrass. Introduced bluestems such as yellow bluestem,
Caucasian bluestem, and introduced kleingrass, blue panicgrass, and buffelgrass are important in the southern and central portions
of this plant growth region. Alfalfa and white sweetclover are the most commonly used legumes. Russian-olive is a satisfactory
woody species in the northern portions and along the foothills of the Rocky Mountains. Junipers, hackberry, and skunkbush sumac
are important native species. Osage-orange is well adapted to the eastern part of this area. Desirable woody plants require special
management for use on most drastically disturbed lands.
Table 9-10. Southern Plains
This area is the Rio Grande Plains of south and southwest Texas. The characteristic grasses on sandy soils are seacoast bluestem,
two-flow trichloris, silver bluestem, big sandbur, and tanglehead. The dominant grasses on clay and clay loams are silver bluestem,
Arizona cottontop, buffalograss, curlymesquite, and grama grasses. Indiangrass, switchgrass, seacoast bluestem, and crinkleawn are
common in the oak savannahs.
Old World bluestems, such as yellow and Caucasian bluestems, are satisfactory only where additional moisture is made available.
Natalgrass and two-flower trichloris have shown promise in reclamation plantings.
Table 9-11. Southern Plateaus
The area is made up of the 750- to 2,400-m (2,450- to 7,875-ft) altitude plateaus of western Texas, New Mexico, and Arizona. The
area includes a large variety of ecological conditions resulting in many plant associations. Creosote-tarbush desert shrub, grama
grassland, yucca and juniper savannahs, pinyon pine, oak, and some ponderosa pine associations occur. Little bluestem, sideoats
grama, green sprangletop, Arizona cottontop, bush muhly, plains bristlegrass, vine-mesquite, blue grama, black grama, and many
other species are common and are useful in reclamation plantings, depending on the site conditions and elevation.
Table 9-12. Intermountain Desertic Basins
This region occupies the extensive intermountain basins from southern Nevada and Utah, north through Washington, and includes
the basin areas of Wyoming. The natural vegetation ranges from almost pure stands of short grasses to desert shrub. There are
extensive area dominated by big sagebrush or other sagebrush species.
A wide variety of species of grasses is available for this area. Among the most commonly used species are the introduced Siberian
wheatgrass, crested wheatgrass, intermediate wheatgrass, pubescent wheatgrass, tall wheatgrass, and hard fescue. Native grasses
used include bluebunch wheatgrass, beardless wheatgrass, big bluegrass, Idaho fescue, and Indian ricegrass. Four-wing and Nuttall
saltbush have performed well in planting trials. Available woody species are limited, though junipers, Russian-olive, skunkbush
sumac, and other native and introduced woody plants are adapted to the climate where moisture is adequate.
Table 9-13. Desert Southwest
This is the desert of southwestern Arizona, southern Nevada, and southern California. Creosotebush may occur in almost pure
stands or with tarbush. Triangle bur-sage, white bur-sage, rubber rabbitbrush, and ocotillo are prominent on some sites. Large
numbers of annual and perennial forbs are present. Saltbushes, winterfat, and spiny hopsage are common. The few grasses present
in the understory are largely big galleta, desert saltgrass, grama grasses, and species of threeawns.
Only minor success has been obtained in establishing vegetation on disturbed lands in the desert southwest. Irrigation for
establishment may be essential in some areas, and the longevity of stands when irrigation is discontinued is not known. Big galleta
and bush muhly show promise. Native shrubs such as creosotebush, fourwing saltbush, and catclaw have also been established.
Reseeding annuals such as goldfields, California poppy, and Indianwheat have also shown promise.
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Table 9-14. California Valleys
The climate of the central California Valleys is classified as semiarid to arid and warm and the moisture is deficient at all seasons.
The largest area of grassland lies around the edge of the central valley and is dominated by annual species. The only areas
remaining in grass in the valley are usually too alkaline for crop production. The grasses remaining in these sites are desert
salt-grass and alkali sacaton.
Recommended for seeding in the area of more than 40 cm (15.8 in) annual precipitation is a mixture of "Luna" pubescent
wheatgrass, "Palestine" orchardgrass, and rose clover. Crimson clover, California poppy, and "Blando" brome can be added.
Inland in the 30 cm (12 in) precipitation areas, a mixture of "Blando" brome, Wimmera ryegrass, and "Lana" woolypod vetch is
recommended. In the 15- to 30-cm (6 to 12 in) precipitation zone "Blando" brome (soft chess) and rose clover are generally used.
Table 9-15. Some Sucessful Plant Species and Species Mixtures Used in Various Sludge Reclamation Projects (Sopper, 1993)
State
CO
IL
IL
IL
IL
IL
IL
MD
OH
Species
Slender wheatgrass3
Intermediate wheatgrass3
Pubescent wheatgrass3
Crested wheatgrass3
Smooth brome3
Meadow brome3
Timothy3
Orchardgrass3
Tall fescue
Weeping lovegrass
K-31 tall fescue
Weeping lovegrass
Common bermudagrass3
Sericea lespedeza3
Kobe lespedeza3
Perennial rye grass3
Potomac orchardgrass13
Sericea lespedezab
Kobe lespedezab
Potomac orchardgrass0
Penngift crownvetchc
Tall fescue
Perennial ryegrass
Western wheatgrass
Reed canarygrass
Tall fescue
Redtop
Alfalfa3
Bromegrass3
Tall fescue3
Tall fescue
Birdsfoot trefoil
Fall, balbo rye
Seeding Rate (kg/ha"1)
5.1
4.8
4.6
3.8
4.6
2.6
1.5
1.4
22
8
22
7.8
11
28
11
22
17
22
11
22
17
25
25
25
34
46
17
22.9
9.5
9.1
40
10
9.6 (bu/ha'1)
State
OK
PA
PA
PA
PA
Species
Spr., K-31 tall fescue3
Korean lespedeza3
Sweet clover3
Orchardgrass3
Switchgrass
Kleingrass
Reed canarygrass
Tall fescue
Orchardgrass
Birdsfoot trefoil
Crownvetch
Deertongue
Switchgrass
Alfalfa
Ladino clover
K-31 tall fescue3
Birdsfoot trefoil3
Rye grass3
Tall fescue3
Orchardgrass3
Birdsfoot trefoil3
Crownvetch3
Blackwell Switchgrass
Niagara big bluestem
Birdsfoot trefoil3
K-31 tall fescue3
Perennial ryegrassb
Lathco flatpeab
Oahe intermediate
Wheat grass
Tall fescuec
Orchardgrass0
Crownvetch0
Seeding Rate (kg/ha"1)
11
3.4
3.5
3.3
154
154
224
224
224
224
224
224
224
224
224
39
8
6
22
22
11
11
17
34
22
45
22
67
34
22
22
17
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Table 9-15. (continued)
State
PA
VA
VA
Species
K-31 tall fescue3
Orchardgrass3
Birdsfoot trefoil3
Crownvetch3
Tall fescue3
Perennial ryegrass3
Annual ryegrass3
Tall fescueb
Perennial ryeb
Sericea lespedezab
Black locustb
K-31 tall fescue3
Redtop3
Seeding Rate (kg/ha"1)
22
22
11
11
8.4
8.4
8.4
22
22
22
0.8
67
5.6
State Species
Ladino clover3
VA Tall fescue
Weeping lovegrass
Korean lespedeza
VA Ky-31 tall fescue
Wl Canada bluegrass3
Red clover3
Smooth bromeb
Alfalfab
Western wheatgrassc
Alsike clover0
Barleyd
Japanese milletd
(added to above mixtures)d
Seeding Rate (kg/ha'1)
5.6
67.3
22
11.2
80
11
9.7
15.2
11
9.7
11
16.5
8.6
Species with the same superscript letter represent a seeding mixture.
and provides a complete protective cover during the first
year, while also allowing time for the legume species to
become established and develop into the final vegeta-
tive cover. The grasses will also take up a large amount
of the nitrogen, preventing it from leaching into the
ground water. Since legume species can fix nitrogen
from the atmosphere, additional sewage sludge nitrogen
additions are often unnecessary.
If a site is to be reforested, it is still generally desirable to
seed it with a mixture of grasses and legumes. The initial
grass and legume cover helps to protect the site from
erosion and surface runoff and takes up the nutrients
supplied by the sewage sludge. Planting slow-growing
tree species is generally not recommended because of
the extreme competition from the fast-growing herba-
ceous vegetation. Fast-growing hardwoods seem to
survive and grow well because they can usually compete
successfully. Suitable species might be black locust, hybrid
poplar, European alder, Catalpa, and European larch.
9.4.2 Seeding and Mulching
Herbaceous species can be seeded by direct drill or
broadcast, hydroseeding, or aerial seeding. Disturbed
sites, however, often are too rocky and irregular for drill
seeding. Broadcast seeding is generally more desirable
because the stand of vegetation produced is more natu-
ral in appearance, with a more uniform and complete
cover, and is effective in erosion prevention and site
stabilization. Broadcasting also achieves a planting
depth that is better suited to the variety of different sized
seeds usually found in mixtures of species. Aerial broad-
cast seeding may also be useful for large tracts. It is
generally not necessary to coverthe seed, since the first
rainfall will normally push the seed into the loosened
surface spoil and result in adequate coverage.
On sites that have good topsoil, agricultural seeding
rates can be used. On abandoned sites, however, it may
be necessary to apply much larger amounts of seed
(Sopper and Seaker, 1983). Mulching is generally not
necessary except on specific sites. Mulching involves
applying organic or inorganic materials to the soil sur-
face to protect the seed, reduce erosion, modify ex-
tremes in surface spoil temperatures, and reduce
evaporation. Mulching is generally advisable on steep
slopes and on black anthracite refuse or fly ash banks
to protect germinating vegetation from high surface tem-
peratures, which may be lethal to most plants. Mulching
may also be required by some state regulatory agencies
for specific situations. Materials used for mulching are
straw, hay, peanut hulls, corn cobs, bagasse, bark, saw-
dust, leaves, and wood chips.
9.5 Sewage Sludge Application Methods
9.5.1 Transportation
Chapter 14 discusses sewage sludge transport in detail.
A special consideration in transport of sewage sludge to
reclaimed mined land is the potential to backhaul sew-
age sludge (i.e., use the same trucks, railcars, etc., that
transport the mined ore to the city for transporting the
sewage sludge from the city back to the mining area).
For example, in 1981-82, the city of Philadelphia back-
hauled about 54,432 t (60,000 T) of sewage sludge
annually in coal trucks a distance of 450 km (280 mi) to
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help reclaim strip mine sites in western Pennsylvania
(Sopperet al., 1981).
9.5.2 Site Preparation Prior to Sewage
Sludge Application
Under federal and state mining regulations, disturbed
mine sites generally must be graded after mining to the
approximate original contour of the area. Abandoned
areas where no regrading has been done should also
be regraded to a relatively uniform slope of less than 15
percent prior to sewage sludge application.
9.5.2.1 Scarification
Prior to sewage sludge application, the soil surface
should be roughened or loosened to offset compaction
caused during the leveling or grading operation. This will
help to improve surface water infiltration and permeability
and slow the movement of any surface runoff and ero-
sion. A heavy mining disk or chisel plow is typically
necessary to roughen the surface. It is advisable that
this be done parallel to the site contours.
9.5.2.2 Debris Removal
Preparing a site for land reclamation may require the re-
moval of debris from mining, construction, or other opera-
tions previously conducted at the site. The extent to which
debris must be removed depends on the post-reclamation
use. For example, if agricultural activities are planned, the
top 60 cm (24 in) should be free of foreign material of
any significant size (Gschwind and Pietz, 1992). If the
site is to be revegetated for erosion control, debris should
be removed from the top 30 cm (12 in) of soil. If an irrigation
hose is used, extensive rock removal will prevent excessive
wear of the hose (Gschwind and Pietz, 1992).
9.5.2.3 Erosion and Surface Runoff Control
Measures
Surface runoff and soil erosion from the reclamation site
should be controlled. These measures may include ero-
sion control blankets, filter fences, straw bales, and
mulch. It may be necessary to construct diversion ter-
races and/or sedimentation ponds. The local Natural
Resources Conservation Service (formerly the Soil Con-
servation Service) can be contacted for assistance in
designing erosion and surface runoff control plans. In
addition, see Chapter 13 of this manual.
9.5.3 Methods of Application
Methods for land application of sewage sludge include
surface spreading, incorporation, spray irrigation, and
injection. These methods are discussed in Chapter 14.
9.5.4 Storage
Sewage sludge storage will probably be needed at a
reclamation site. The Part 503 regulation defines stor-
age as the placement of sewage sludge on land on
which the sewage sludge remains for two years or less.
Storage may occur at the treatment works and/or at the
land application site. In general, when liquid sewage
sludge is used, storage is provided at the treatment plant
in digesters, holding tanks, or lagoons. At land applica-
tion sites where large quantities of liquid sewage sludge
are used, storage lagoons may be built at the site.
If dewatered sewage sludge is used, storage may be
more advantageously located at the land application
site. Small storage areas may also be desirable at the
treatment plant for times of inclement weather or equip-
ment breakdown.
At currently mined sites, it may be necessary to trans-
port and stockpile dewatered sewage sludge at the site
prior to land application while the area is being backfilled
and topsoiled. This would allow large quantities of sew-
age sludge to be applied in a relatively short period of
time and also allows more efficient use of manpower
and equipment. Some states have specific regulations
concerning sewage sludge stockpiling onsite for short
periods of time. For example, in Pennsylvania, the sew-
age sludge storage area must be diked to prevent sur-
face water from running into or out of the storage area.
9.6 Scheduling
The timing of sewage sludge application depends on the
climate, soil conditions, and growing season. The Part
503 regulation prohibits bulk sewage sludge application
to flooded, frozen, or snow-covered reclamation sites in
such a way that the sewage sludge enters a wetland or
other surface waters (except as provided in a permit
issued under Section 402 or 404 of the Clean Water
Act). Sewage sludge should not be applied during peri-
ods of heavy rainfall because this greatly increases the
chances of surface runoff. Sewage sludge also should
not be applied in periods of prolonged extreme heat or
dry conditions, since considerable amounts of nitrogen
will be lost before the vegetation has a chance to estab-
lish itself. If sewage sludge is applied and allowed to dry
on the soil surface, from 20 to 70 percent of the NH4-N
will be volatilized and lost to the atmosphere as NH3.
The exact amount of NH4-N lost will depend on soil,
sewage sludge, and climate conditions (U.S. EPA, 1978).
Sewage sludge applications should be scheduled to
accommodate the growing season of the selected plant
species. If soil conditions are too wet when sewage
sludge is applied, the soil structure may be damaged,
bulk density increased, and infiltration decreased due to
heavy vehicle traffic on the wet soil. This may increase
the possibility of soil erosion and surface runoff. In ad-
119
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dition, the tractors or trucks may experience difficulty
driving on the wet soil.
If the area to receive sewage sludge is covered under
federal or state mining regulations, the sewage sludge
application must be scheduled to comply with the revege-
tation regulations. For example, in Pennsylvania, mined
land can be seeded in the spring as soon as the ground is
workable, usually early in March, but seeding must termi-
nate by May 15. The late summer seeding season is from
August 1 until September 15. The designer should check
on requirements for his or her locale.
9.7 Determining Sewage Sludge
Application Rates at Reclamation
Sites
9.7.1 General Information
Historically, land application of sewage sludge at recla-
mation sites generally has involved large applications of
sludge to sufficiently establish vegetation, with rates
sometimes exceeding 200 t/ha and no subsequent ap-
plications. Such high application rates almost invariably
exceed agronomic rates for plant nitrogen needs, and can
result in temporary leaching of nitrate into ground water.
The Part 503 rule specifies that, in general, application
of sewage sludge should not exceed the agronomic rate
for N, but that higher rates may be allowed at reclama-
tion sites if approved by the permitting authority. When
determining sewage sludge application rates, it is useful
to draw a general distinction between "reconstructed"
and "abandoned" reclamation sites:
• "Reconstructed" reclamation sites generally include
coal mine reclamation sites that have been or are
being reclaimed according to provisions of the 1977
federal Surface Mining Reclamation and Control Act
(SMCRA), and surface-mine reclamation sites involv-
ing non-coal minerals (such as iron and copper) regu-
lated by other federal or state programs that require
a measure of soil reconstruction after the mineral has
been removed. SMCRA requires grading of spoils to
reestablish the approximate original contour of the
land, the saving and replacement of topsoil on all
areas affected by mining, and additional soil recon-
struction for prime farmlands. Grading of mine spoils
and replacement of topsoil is also a routine practice at
active surface mine sites involving non-coal minerals.
• "Abandoned" reclamation sites are typically aban-
doned coal mine sites, especially those involving
acid- or toxic-forming spoil or coal refuse, where dis-
turbance occurred prior to enactment of SMCRA and
natural revegetation has been sparse. Other mine
sites where mining practices or unfavorable overbur-
den chemistry have resulted in poor vegetation es-
tablishment also can be considered "abandoned" rec-
lamation sites.
Generally, application of sewage sludge at rates exceeding
plant N requirements is not justified at reconstructed rec-
lamation sites, and procedures for determining sewage
sludge application rates should be the same as those
described in Chapter 7 for agricultural crops or Chapter
8 for forest sites. An exception might be where topsoil
was very thin or missing before mining, such as forest
lands on steep slopes with weakly developed soil hori-
zons (Sopper, 1993).
Large, one-time sewage sludge applications that ex-
ceed the agronomic rate for N are most likely to be
justified at abandoned sites, such as abandoned acid
strip mine spoils, where ground-water quality is usually
already severely degraded. At such sites, the long-term
benefits of the large addition of organic matter in the
sewage sludge to the mine spoils for establishing an
improved vegetative cover exceed the short-term effects
of leaching of excess nitrate from the sludge. Section
9.7.2 below describes a procedure for determining ap-
plication rates at abandoned reclamation sites where
the agronomic rate may not be sufficient to reestablish
vegetation.
9.7.2 Approach for Determining a Single,
Large Application of Sewage Sludge at
a Reclamation Site
The approach for determining the maximum acceptable
one-time application of sewage sludge to a reclamation
site is based on evaluating the effect of N in excess of
plant needs from a large application on soil-water ni-
trate concentrations. The main steps in this procedure
involve:
1) Determine the maximum allowable application
rate (Smax) (e.g., based on the Part 503 CPLR
limits, see Chapter 3).
2) Perform N budget calculations to determine the
available N in excess of plant needs (using Smax,
as described in Section 9.7.3).
3) Estimate the soil-water nitrate concentrations that
will result from the excess N from a one-time
application at Smax.
4) If soil-water nitrate concentrations from applica-
tion of Smax are not acceptable, a lower application
rate is set that will not exceed a defined accept-
able soil-water nitrate concentration.
Section 9.7.3 provides a design example that illustrates
this process.
120
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9.7.3 Design Example for a Single, Large
Sewage Sludge Application at a
Reclamation Site
A five-acre area of abandoned acidic mine spoils (pH
3.9) in Kentucky is to be reclaimed using a single large
application of sewage sludge to provide organic matter
and nutrients required to support establishment of a
mixture of grass and legumes, with a first-year N re-
quirement of 300 kg/ha. Based on appropriate soil tests,
it was determined that agricultural lime application of
12.3 t/ha (5.5 T/ac) is sufficient to raise the soil pH to
6.5. The spoils are slowly permeable (0.2 cm/hr). Net
precipitation infiltrating into the ground is estimated to
be 80 cm (31.5 in), of which 20 percent is estimated to
be lost by evapotranspiration. Depth to ground water is
5 m(16ft).
The sewage sludge to be applied has undergone an-
aerobic digestion and has the following characteristics:
• Solids - 4.0 percent
• Organic N - 2.5 percent
• NH4-N - 1.0 percent
• NO3-N - 0 percent
• Total P - 2.0 percent
• Total K - 0.5 percent
• As - 10 mg/kg
• Cd - 10 mg/kg
• Cr - 1,000 mg/kg
• Cu - 3,750 mg/kg
• Pb - 150 mg/kg
• Hg - 2 mg/kg
• Mo - 8 mg/kg
• Ni - 100 mg/kg
• Se - 15 mg/kg
• Zn - 2,000 mg/kg
Step 1. Calculate Maximum Application Based
on Metal Loading
The cumulative pollutant loading rate for a particular
metal is calculated using the following equation:
Smax = L/Cm (1,000 kg/t)
where:
(9-1)
= The total amount of sewage sludge, in
t/ha, that would result in the cumulative
pollutant loading rate limit, L.
L = The Part 503 cumulative pollutant load-
ing rate limit (CPLR) for sewage sludge
in kg/ha (see Chapter 3).
Cm = Concentration, in mg/kg, of the metal of
concern in the sewage sludge being
applied.
The limiting metal in this example is copper, with Smax =
400 t/ha. In reality, most sewage sludges contain lower
copper levels; this higher level is used here to illustrate
an application rate higher than the agronomic rate.
Since sludge applications at 400 t/ha could result in a
high nitrogen impact on ground water during the first two
years of operation, a loading rate of 200 t/ha was se-
lected, which is sufficient for establishing vegetation.
Note that if the copper concentration in the sewage
sludge in this example met Part 503's "pollutant concen-
tration limit" (as do all the other pollutants listed) rather
than the CPLR limit for copper, cumulative metal load-
ings would not be required to be tracked (see Chapter
3), and application rates would not be limited by cumu-
lative pollutant loadings (see Chapter 7, Section 7.4.4.3).
Step 2. Determine Excess N Available for
Leaching
Available N content of the revised Smax (200 t/ha) is
calculated using the following equation:
Np = S [(NOs) + Kv (NH4) + F(year w) (No)] (10) (9-2)
where:
Np = Plant-available N (from this year's sew-
age sludge application only), in kg/ha.
S = Sewage sludge application rate, in dry t/ha.
NOs = Percent nitrate-N in the sewage sludge,
as percent.
Kv = Volatilization factor, usually set at 0.5
for surface-applied liquid sewage
sludge, or 1.0 for incorporated liquid
sludge and dewatered sludge applied in
any manner.
NH4 = Percent ammonia-N in the sewage
sludge, as percent (e.g., 1% = 1.0).
FiyearO-i)= Mineralization factor for organic N in
the sewage sludge in the first year, ex-
pressed as a fraction (e.g., 0.2).
No = Percent organic N in the sewage
sludge, as percent (e.g., 2.5% = 2.5).
Since the sludge is to be surface applied, KV = 0.5.
NP1 = 200 [(0.0) + (0.5)(1.0) + (0.2)(2.5)] (10)
= 2,000 kg/ha
Available N in the second year after the one-time appli-
cation is simply the amount mineralized from the initial
application, using the following equation:
121
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Nm = (S) (Km) (N0)
where:
(9-3)
Quantity of N0 mineralized in the year
under consideration, in kg/ha.
Sewage sludge application rate, in dry
t/ha.
Mineralization factor for the year under
consideration, expressed as a fraction.
Percent organic N originally present in
the sewage sludge, as percent (e.g.,
2.5% = 2.5).
Nm
S
Km
No
In this example, for illustrative purposes, K^ = 0.80 and
Km3 = 0.36 in the second and third years respectively for
anaerobic sludge. Thus:
Nm2 = (200) (0.80) (2.5)
= 400 kg/ha
Nm3 = (200) (0.36) (2.5)
= 180 kg/ha
A simplified N budget for the Smax sludge application for
the first three years after application is as follows, with
Nr representing plant uptake (300 kg/ha):
Year 1 : Nexcess = Npi - Nr = 2,000 - 300 = 1 ,700 kg/ha
Year 2: Nexcess = Nm2 - Nr = 400 - 300 = 100 kg/ha
Year 3: Nexcess = Nms - Nr = 100 - 300 = 0 kg/ha
In the first year, available N is more than 6 times the
plant uptake, and by the second year is slightly more
than plant uptake. In the third year, mineralized N is less
than potential plant uptake. Consequently, with a one-time
large application of sewage sludge, leaching of nitrate
can be expected during the first year, with minimal
leaching in the second year and no leaching in the third
year. These N budget calculations have been simplified
for this illustrative example; the more detailed annual N
budget calculations contained in the Worksheets in
Chapter 7 can also be used.
Step 3. Calculation of Potential Nitrate
Leaching into Ground Water
It is possible to make a conservative estimate of the
quantity of nitrates potentially leaching into the ground
water by calculating the maximum potential concentra-
tion of excess nitrates percolating from the site into the
underlying aquifer. This is done by assuming that all N
in excess of plant needs is converted to nitrates, and that
no dilution of percolate occurs in existing ground water.
Assume annual net infiltration of precipitation, PI =
80 cm.
Assume evapotranspiration losses, ET = 20% =
0.20.
If all of the excess nitrogen in the sludge applied is
mobile (an unlikely and very conservative assumption),
the concentration of nitrate in the percolate is calculated
using the following equation:
Soil Water NO3, mg/L =
kg/ha) (10s mg/kg) (1,000 cm3/L)
(108 cm2/ha) (P,, cm) (1-ET)
(1,700 kg/ha) (10s mg/kg) (1,000 cm3/L)
(108 cnf/ha) (80 cm) (1-0.20)
= 266 mg/L
Repeating the calculation for the excess N in the
second year indicates a maximum NO3 concentration
of 16 mg/L. By the third year, the site would meet the
nitrate drinking water MCL of 10 mg/L because no ex-
cess N exists.
If the potential concentration of nitrate-N in the percolate
that exceeds the MCL during the first two years after
sewage sludge application is unacceptable to the regu-
latory agency, even though by the third year leaching
effects are minimal, and if there is no extraction of
potable water from the aquifer, maximum sludge appli-
cation rates can be calculated based on a maximum
acceptable level of NO3 in percolating soil water.
Additional information on the design of mine land recla-
mation projects using municipal sewage sludge can be
found in the Manual for the Revegetation of Mine Lands
in Eastern United States Using Municipal Biosolids
(Sopper, 1994).
9.8 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
Bennett, O.L., E.L. Mathias, W.H. Arminger, and J.N. Jones, Jr. 1978.
Plant materials and their requirements for growth in humid re-
gions. In: Schaller, F.W., and P. Sutton, eds. Reclamation of dras-
tically disturbed lands. American Society of Agronomy, Madison,
Wl. pp. 285-306.
122
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Berg, W.A. 1978. Limitations in the use of soil tests on drastically
disturbed lands. In: Schaller, F.W., and P. Sutton, eds. Reclamation
of drastically disturbed lands. American Society of Agronomy,
Madison, Wl. pp. 653-664.
Berry, C.R. 1982. Sewage sludge aids reclamation of disturbed forest
land in the southeast. In: Sopper, W.E., E.M. Seaker, and R.K.
Bastian, eds. Land reclamation and biomass production with mu-
nicipal wastewater and sludge. Pennsylvania State University
Press, University Park, PA. pp. 307-316.
Fed. Reg. 1982. Surface coal mining and reclamation permanent
program regulations: revegetation. March 23.
Gschwind, J., and R. Pietz. 1992. Application of municipal sewage
sludge to soil reclamation sites. In: Lue-Hing, C., D. Zenz, and R.
Kuchenrither, eds. Municipal sludge management: Processing,
utilization, and disposal. Water Quality Management Library, Vol.
4. Lancaster, PA: Technomic Publishing Company, pp. 455-478.
Jacobs, L., S. Carr, S. Bohm, S., and J. Stukenberg. 1993. Document
long-term experience of biosolids land application programs. Pro-
ject 91-ISP-4, Water Environment Research Foundation, Alexan-
dria, VA.
Pennsylvania Department of Environmental Resources. 1988. Land
application of sewage sludge. In: Rules in the Pennsylvania Code,
Title 25, Chapter 275.
Peterson, J., C. Lue-Hing, J. Gschwind, R. Pietz, and D. Zenz. 1982.
Metropolitan Chicago's Fulton County sludge utilization program.
In: Sopper, W, E. Seaker, and R. Bastian, eds. Land reclamation
and biomass product with municipal wastewater and sludge. Uni-
versity Park, PA: Pennsylvania State University Press. Cited in
Gschwind and Pietz, 1992.
Pietz, R., J. Peterson, T. Hinesly, E. Ziegler, K. Redborg, and C.
Lue-Hing. 1982. Sewage sludge application to calcareous strip-
mine spoil: I, Effect on corn yields and N, P, Ca, and Mg compo-
sitions. J. Environ. Quality 18:685-689. Cited in Gschwind and
Pietz, 1992.
Rafaill, B.L., and WG. Vogel. 1978. A guide for vegetating surface-
mined lands for wildlife in eastern Kentucky and West Virginia.
FWS/OBS-78-84. U.S. Fish and Wildlife Service, Washington, DC.
Sopper, W. 1994. Manual for the revegetation of mine lands in the
eastern United States using municipal biosolids. Morgantown, WV:
West Virginia University, National Mine Land Reclamation Center.
Sopper, W. 1993. Municipal sludge use in land reclamation. Boca
Raton, FL: Lewis Publishers.
Sopper, W, and S. Kerr. 1982. Mine land reclamation with municipal
sludge—Pennsylvania demonstration program. In: Sopper, W.E.,
E.M. Seaker, and R.K. Bastian, eds. Land reclamation and
biomass product with municipal wastewater and sludge. University
Park, PA: Pennsylvania State University Press, pp. 55-74.
Sopper, W, S. Kerr, E. Seaker, W. Pounds, and D. Murray. 1981. The
Pennsylvania program for using municipal sludge for mine land
reclamation. In: Proceedings of the Symposium on Surface Mining
Hydrology, Sedimentology, and Reclamation. University of Ken-
tucky, Lexington, KY. pp. 283-290.
Sopper, W., and E. Seaker. 1983. A guide for revegetation of mined
land in the eastern United States using municipal sludge. Univer-
sity Park, PA: Pennsylvania State University Institute for Research
on Land and Water Resources.
U.S. Department of Interior. 1979. Permanent regulatory program
implementing Section 501 (b) of the Surface Mining Control and
Reclamation Act of 1977; Final Environmental Statement. OSM-
EIS1. Washington, DC.
U.S. EPA. 1978. Sludge treatment and disposal, Vol. 2. Center for
Environmental Research Information, Cincinnati, OH. EPA/625/4-
78/012 (NTIS PB-299593).
U.S. Soil Conservation Service. 1977. The status of land disturbed by
surface mining in the United States. SCS-TP-158. Washington, DC.
123
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Chapter 10
Land Application at Public Contact Sites, Lawns, and Home Gardens
10.1 General
In addition to land application at agricultural, forest, and
reclamation sites, sewage sludge and domestic septage
can be land applied to lawns and home gardens as well
as "public contact sites." The Part 503 regulation defines
public contact sites as land with a high potential for
contact by the public, such as parks, ball fields, ceme-
teries, plant nurseries, turf farms, and golf courses. In
many cases, sewage sludge is applied to these types of
sites from bags or other containers1 that are sold or
given away (hereafter referred to as "bagged" sewage
sludge), although sewage sludge also can be land ap-
plied to these types of sites in bulk form. Often the
sewage sludge used at these sites is processed and
marketed by municipalities or private firms as a brand-
name fertilizer and/or soil conditioning product. Design-
ing land application programs geared toward public
contact sites, lawns, and home gardens may be particu-
larly useful for municipalities with limited land available
(e.g., highly populated areas with few agricultural, for-
est, or reclamation sites available for sewage sludge
application).
This chapter discusses how the Part 503 requirements
pertain to land application of sewage sludge and domes-
tic septage at public contact sites, lawns, and home
gardens (Section 10.2). Important factors to consider in
designing a marketing program for sewage sludge to be
land applied at public contact sites, lawns, and home
gardens are discussed in Section 10.3.
10.2 Part 503 Requirements
Many of the strictest requirements in Part 503 must be
met for sewage sludge or domestic septage that is land
applied to public contact sites, lawns, and home gar-
dens (e.g., Class A pathogen reduction; for metals, an-
nual pollutant loading rate limits for bagged sewage
sludge or pollutant concentration limits for bulk sewage
sludge, see Chapter 3). Domestic septage applied to
public contact sites, lawns, or home gardens must meet
the same requirements as bulk sewage sludge that is
land applied, although less burdensome requirements
pertain to domestic septage applied to other types of
land (agricultural, forest, or reclamation sites), as de-
scribed in Chapter 11. The stringent requirements are
specified for sewage sludge that is land applied to public
contact sites, lawns, and home gardens because of the
high potential for human contact with sewage sludge at
these types of sites and because it is not feasible to
impose site restrictions when sewage sludge is sold or
given away in bags or other containers for application to
the land. The sewage sludge used in this manner must
meet the requirements for metals, pathogens, vector
attraction reduction, management practices, and other
requirements specified in Part 503 for application to
these types of sites, as discussed in Chapter 3.
The effects of the Part 503 regulation on current sewage
sludge land application programs depends on the qual-
ity of the sewage sludge. If a sewage sludge meets
certain Part 503 requirements, the sewage sludge can
be considered "exceptional quality" (EQ), as discussed
in Chapter 3. EQ sewage sludge can be applied as
freely as any other fertilizer or soil amendment to any
type of land. If EQ sewage sludge requirements are met,
current land application operations, including those
with already successful marketing programs for sew-
age sludge (see Section 10.3), may continue with a
minimum of additional regulatory requirements. Forsew-
age sludge preparers2 who have difficulty meeting the Part
503 requirements for public contact sites, lawns, or home
gardens, operational changes may need to be imple-
mented to further reduce pathogen or metal levels for
land application at these types of sites. The types of
sewage sludge treatment and preparation that can
achieve EQ-quality sewage sludge (e.g., heat drying)
are discussed in Chapter 3.
10.3 Marketing of Sewage Sludge
After processing to achieve Part 503 requirements, sew-
age sludge that is to be land applied at public contact
1 The Part 503 regulation defines "other containers" as open or closed
receptacles, such as buckets, boxes, carton, or vehicles, with a load
capacity of 1 metric ton or less.
"The Part 503 regulation defines a person who prepares sewage
sludge as either the person who generates sewage sludge during
the treatment of domestic sewage in a treatment works or the person
who derives a material from sewage sludge.
125
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sites, lawns, and home gardens often is marketed to
distributors or end users (e.g., landscapers, home gar-
deners), frequently as bagged sewage sludge. Designing
a marketing program for sewage sludge has some simi-
larities to marketing any commercial product, including:
• Maintaining the "high quality" of the product
• Ensuring the product is readily available
• Developing and maintaining product demand
• Offering competitive pricing
Two marketing factors particularly relevant to sewage
sludge are:
• Maintaining good public relations
• Ensuring that the operations are acceptable to the
community
Having a diversified range of products may be useful. In
the case of sewage sludge, this might include producing
a Class B bulk sewage sludge for agricultural, forest,
and reclamation sites, and a Class A bagged sewage
sludge product, such as compost, for use by landscapers,
public works departments, and the public.
10.3.1 De veloping Product Demand
To create and maintain product demand, many munici-
palities or private firms use a trade name to enhance
marketability, such as Milorganite, a heat-dried, bagged
sewage sludge produced by the city of Milwaukee, Wis-
consin, and Philorganic, a composted sewage sludge
produced by the city of Philadelphia, Pennsylvania.
Other cities that produce heat-dried sewage sludge in-
clude Chicago, Houston, Atlanta, Tampa Bay, and New
York City. Municipalities that produce composted sew-
age sludge include the District of Columbia, Kittery
(Maine), Denver, Missoula (Montana), and Los Angeles.
Some municipalities also conduct market surveys to
determine who would be interested in purchasing their
product; use agricultural professionals as sales agents;
advertise in professional journals and the mass media;
and contract with an intermediary for distribution.
The wastewater treatment plant or other preparer of
sewage sludge may be able to increase marketability by
offering the customer various important "services," such
as (Warburton, 1992):
• Storing the user's purchased sewage sludge at the
wastewater treatment plant (in accordance with Part
503 provisions).
• Providing the user with results of nutrient, pollutant,
and any ground-water, surface water, or plant tissue
sampling tests.
• Offering dependable transport to the land application
site at times suitable for land application.
• Assisting in obtaining required permits.
• Performing reliable inventory management, so that
the "product" is always available when needed.
In many cases, marketing of sewage sludge can include
promoting the concept of reuse/recycling. For exam-
ple, the City of Los Angeles now reuses 100% of its
300 dT/day of sludge through agricultural land applica-
tion (at various sites), as soil cover at a landfill, and
composting. Los Angeles has implemented several in-
novative sewage sludge marketing programs. One is the
"Full Cycle Recycle" composting program, which in-
cludes public education for LA's "Topgro" soil amend-
ment/compost product. Topgro is produced from city
wastes (sewage sludge and/or yard trimmings), proc-
essed locally, and marketed as "home grown" to local
nurseries, retailers, and City agencies in bulk or bag at
competitive prices. Another LA sewage sludge market-
ing program is a cooperative composting project be-
tween the city's Department of Public Works and
Department of Recreation and Parks, in which sewage
sludge, zoo manure, and plant wastes are processed
and used as compost at city parks; the composting
facility also serves as an educational center for the
public (Molyneux et al., 1992).
10.3.2 Marketing Cost Considerations
The costs of a sewage sludge marketing program may
be high relative to costs of direct land application. Major
cost factors include:
• Dewatering the sewage sludge.
• Composting, heat drying, or other processes to
achieve adequate pathogen reduction and vector
attraction reduction.
• Market development.
• Transportation.
Dewatering and other processing can involve significant
capital expenditures. Some generators/preparers of
sewage sludge may choose to contract out some proc-
essing technologies, which can be done through com-
petitive bidding between vendors that produce similar
products (e.g., a heat-dried product, compost, certain
alkaline stabilization processes that meet Part 503
Class A pathogen reduction requirements) to reduce
program costs (Warburton, 1992). The City of Los An-
geles has reduced its sludge management program
costs by an average of $3 per dry ton as a result
of improved management, decreased transportation
times, price rebates, volume discounts, and minimizing
truck loading times (Molyneux et al., 1992).
A marketing program for sewage sludge always should
include examination of the costs of transporting the sew-
age sludge. Transportation costs may include conveying
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the sludge from the wastewater treatment plant to the
processing center, transport of bulking materials for
composting, and distribution of the finished sewage
sludge product. Although extending the geographical
marketing area would increase shipping costs, it may be
worthwhile if it is likely that potential buyers in the ex-
tended area are willing to pay a higher price for the
product.
Some municipalities charge the distributor or end user
for the use of a sewage sludge product, as shown in
Table 10-1. The table indicates that from 38% to 60% of
POTWs sell their sludge at rates ranging from $4 to $6 per
cubic yard or $34 to $63 per ton. In some cases, the
municipality may not make a "profit" from selling sewage
sludge, but the sales can reduce operating costs for
overall sewage sludge management. In other cases, the
sewage sludge generator or preparer pays the land-
owner or person responsible for land applying sewage
sludge if payment results in lower sewage sludge man-
agement costs.
In some localities, demand has exceeded supply for
marketed sewage sludge. In other areas, marketed sew-
age sludge programs have failed because of poor or
inconsistent product quality or operational practices un-
acceptable to the community. Demand for sewage
sludge for land application tends to be seasonal, peak-
ing in the spring and fall in areas with four-season
climates. In areas with mild climates year-round, a con-
stant market can be developed.
Table 10-1. Percent of POTWs Selling Sewage Sludge and
Mean Price of Sewage Sludge Sold (Adapted
From U.S. EPA, 1990)
Reported Flow
Rate Group3
1
2
3
4
% of POTWs
That Sellb
60.0%
71.4
42.1
37.5
Price Per
Ton0
$63
34
-
-
Price Per
Cubic Ydc
$5
6
4
6
3 Flow rate group 1=>100MGD;2 = >10-100MGD;3 = >1-10MGD;
4 = 0-1 MGD.
b Percents based on a total of 46 POTWs.
c 50% of the POTWs who reported that they sold sewage sludge
provided price data.
10.4 References
Molyneux, S., R. Fabrikant, and C. Peot. 1992. Waste to resource:
The dynamics of a sludge management program. In: Proceedings
of the future direction of municipal sludge (biosolids) manage-
ment: Where we are and where we're going, Vol. I, Portland, OR.
Water Environment Federation, Alexandria, VA.
U.S. EPA. 1990. National sewage sludge survey: Availability of infor-
mation and data, and anticipated impacts on proposed regula-
tions. Fed. Reg. 58:18.
Warburton, J. 1992. So, you're convinced sludge is a valuable re-
source—Then market it like a perishable commodity. In: Proceed-
ings of the future direction of municipal sludge (biosolids)
management: where we are and where we're going, Vol. 1, Port-
land, OR. Water Environment Federation, Alexandria, VA.
127
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Chapter 11
Land Application of Domestic Septage
11.1 General
Land application of domestic septage is an economical
and environmentally sound practice used by many rural
communities. Like land application programs for other
types of sewage sludge, a properly managed land ap-
plication program for domestic septage can benefit from
the reuse of the organic matter and nutrients in the
domestic septage without adversely affecting public
health. Sometimes, however, finding suitable sites,
overcoming local opposition, or meeting regulatory re-
quirements may be difficult. The Part 503 regulation
governing the use or disposal of sewage sludge, prom-
ulgated in February 1993, includes simplified require-
ments for the land application of domestic septage
(compared to more extensive requirements for other
types of sewage sludge generated by a wastewater
treatment plant). While the Part 503 rule provides mini-
mum guidelines for state programs, individual state
regulations may be more stringent.
The Part 503 regulation includes minimum requirements
for the application of domestic septage to land used
infrequently by the general public, such as agricultural
fields, forest land, and reclamation sites.
For land application of domestic septage to land where
public exposure potential is high, however (i.e., public
contact sites or home lawns and gardens), the same
Part 503 requirements as those for bulk sewage sludge
applied to the land must be met (i.e., general require-
ments, pollutant limits, pathogen and vector attraction
reduction requirements, management practices, fre-
quency of monitoring requirements, and recordkeeping
and reporting requirements) (U.S. EPA, 1994a). See
Chapter 3 for a discussion of each of these provisions
of the Part 503 rule.
The remainder of this chapter focuses on the land ap-
plication of domestic septage to agricultural land, for-
ests, or reclamation sites. For additional information on
applications to these types of land, see Domestic Sep-
tage Regulatory Guidance: A Guide To Part 503 (U.S.
EPA, 1993).
11.1.1 Definition of Domestic Septage
Domestic septage is defined in the Part 503 regulation
as the liquid or solid material removed from a septic
tank, cesspool, portable toilet, Type III marine sanitation
device, or a similar system that receives only domestic
sewage (water and wastewater from humans or house-
hold operations that is discharged to or otherwise enters
a treatment works). Domestic sewage generally in-
cludes wastes derived from the toilet, bath and shower,
sink, garbage disposal, dishwasher, and washing ma-
chine. Domestic septage may include household sep-
tage as well as septage from establishments such as
schools, restaurants, and motels, as long as this sep-
tage does not contain other types of wastes than those
listed above.
Domestic septage characteristics are presented in Ta-
ble 11-1 (conventional wastewater parameters and nu-
trients) and Table 11-2 (metals and organics) (U.S.
EPA, 1994a).
Table 11-1. Characteristics of Domestic Septage:
Conventional Parameters (U.S. EPA, 1994b)
Parameter
Concentration (mg/L)
Average Minimum Maximum
Total solids
Total volatile solids
Total suspended solids
Volatile suspended solids
Biochemical oxygen demand
Chemical oxygen demand
Total Kjeldahl nitrogen
Ammonia nitrogen
Total phosphorus
Alkalinity
Grease
PH
34,106
23,100
12,862
9,027
6,480
31,900
588
97
210
970
5,600
—
1,132
353
310
95
440
1,500
66
3
20
522
208
1.5
130,475
71 ,402
93,378
51 ,500
78,600
703,000
1,060
116
760
4,190
23,368
12.6
129
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Table 11-2. Characteristics of Domestic Septage: Metals and
Organics (U.S. EPA, 1994b)
Concentration (mg/L)
Parameter
Average
Minimum
Maximum
Metals
Iron
Zinc
Manganese
Barium
Copper
Lead
Nickel
Chromium (total)
Cyanide
Cobalt
Arsenic
Silver
Cadmium
Tin
Mercury
39.3
9.97
6.09
5.76
4.84
1.21
0.526
0.49
0.469
0.406
0.141
0.099
0.097
0.076
0.005
0.2
< 0.001
0.55
0.002
0.01
< 0.025
0.01
0.01
0.001
< 0.003
0
< 0.003
0.005
< 0.015
0.0001
2740
444
17.1
202
261
118
37
34
1.53
3.45
3.5
5
8.1
1
0.742
Organics
Methyl alcohol
Isopropyl alcohol
Acetone
Methyl ethyl ketone
Toluene
Methylene chloride
Ethylbenzene
Benzene
Xylene
15.8
14.1
10.6
3.65
0.17
0.101
0.067
0.062
0.051
1
1
0
1
.005
0.005
0.005
0.005
0.005
396
391
210
240
1.95
2.2
1.7
3.1
0.72
11.1.2 Domestic Septage Versus
Industrial/Commercial Septage
The specific definition of domestic septage in the Part 503
regulation does not include many materials that are often
called septage by industry. Commercial and industrial sep-
tage are not considered domestic septage. The factor that
differentiates commercial and industrial septage from domes-
tic septage is the type of waste being produced (a treatment
works, e.g., a septic tank, receiving domestic sewage), rather
than the type of establishment generating the waste. For
example, sanitation waste and residues from food and nor-
mal dish cleaning from a restaurant are considered domestic
sewage, whereas grease trap wastes from a restaurant are
classified as commercial septage. If restaurant grease trap
wastes are included with domestic septage in a truckload,
then the whole truckload is not covered by the Part 503
regulation (U.S. EPA, 1993). Instead, commercial and
industrial septage and mixtures of these septages with
domestic septage are regulated under 40 CFR Part 257
if the septage is used ordisposed on land. Industrial and
commercial septage containing toxic compounds or
heavy metals require special handling, treatment, and
disposal methods; a discussion of these methods is
beyond the scope of this manual.
11.2 Regulatory Requirements for Land
Application of Domestic Septage
11.2.1 Determining Annual Application Rates
for Domestic Septage at Agricultural
Land, Forests, or Reclamation Sites
Federal requirements that have been established under
Part 503 for land application of domestic septage are
discussed in Chapter 3. According to the Part 503 regu-
lation, the maximum volume of domestic septage that
may be applied to agricultural land, forest land, or a
reclamation site during a 365-day period depends on the
amount of nitrogen required by the crop for the planned
crop yield. The maximum volume for domestic septage
is calculated by the following formula:
AAR:
N
0.0026
Where:
AAR =
N
Annual application rate in gallons per
acre per 365 day period.
Amount of nitrogen in pounds per acre
per 365 day period needed by the crop
or vegetation grown on the land.
For example, if 100 pounds of nitrogen per acre is
required to grow a 100 bushel per acre crop of corn, then
the AAR of domestic septage is 38,500 gallons per acre
(U.S. EPA, 1993):
AAR =
= 38,500 gal Ion ^ere/year
Application rate requirements pertain to each site where
domestic septage is applied and must be adjusted to the
nitrogen requirement for the crop being grown (U.S. EPA,
1 993). Nitrogen requirements of a crop depend on expected
yield, soil conditions, and other factors such as temperature,
rainfall, and length of growing seasons. Local agricultural
extension agents should be contacted to determine the
appropriate nitrogen requirements for use in the above
equation for calculation of the application rate.
Table 11-3 outlines typical nitrogen requirements of vari-
ous crops and corresponding domestic septage applica-
tion rates (U.S. EPA, 1993). These values are listed as
general guidance only; more specific information on the
130
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Table 11-3. Typical Crop Nitrogen Requirements and
Corresponding Domestic Septage Application
Rates (U.S. EPA, 1993)
Corn
Oats
Barley
Grass & Hay
Sorghum
Peanuts
Wheat
Wheat
Soybeans
Cotton
Cotton
Expected
Yield
(bushel/acre/
year)
100
90
70
4 tons/acre
60
40
70
150
40
1 bale/acre
1 .5 bales/acre
Nitrogen
Requirement
(Ib N/acre/
year)1
100
60
60
200
60
30
105
250
30
50
90
Annual
Application
Rate
(gallons/acre/
year)
38,500
23,000
23,000
77,000
23,000
11,500
40,400
96,100
11,500
19,200
35,000
1 These figures are very general and are provided for illustration
purposes. They should not be used to determine your actual appli-
cation rate. Crop fertilization requirements vary greatly with soil type.
Expected yields and climatic conditions are also important factors
in determining the appropriate volume of domestic septage to apply
to a particular field. Different amounts of nutrients can be required
by the same crop grown in different parts of the country. To get more
specific information on crop fertilization needs specific to your loca-
tion, contact local agricultural extension agents.
amount of nitrogen required for the expected crop yield
under local soil and climatic conditions should be ob-
tained from a qualified, knowledgeable person, such as
a local agricultural extension agent. The crop nitrogen
requirement is then used in the annual application rate
formula to calculate the gallons per acre of domestic sep-
tage that can be applied.
While not required by the Part 503 rule, it is important
that the septic tank pumper inform the landowner or
lease holder of the land application site regarding how
much of the crop's nitrogen requirement was added by
the applied domestic septage. This information will allow
the land owner to determine how much additional nitro-
gen, if any, in the form of chemical fertilizer will need to
be applied (U.S. EPA, 1993). The pumper should also
inform the landowner/leaser of any site restrictions.
11.2.1.1 Protection of Ground Water from
Nitrogen Contamination
The primary reason for requiring the annual rate calcula-
tion is to prevent the over-application of nitrogen in excess
of crop needs and the potential movement of nitrogen
through soil to ground water. The annual application rate
formula was derived using assumptions that facilitate
land application of domestic septage. For example, frac-
tional availability of nitrogen from land-applied domestic
septage was assumed over a 3-year period to obtain the
0.0026 factor in the application formula. Also, in deriving
the formula, domestic septage was assumed to contain
313 mg/l per year available nitrogen (in year three and
thereafter) (U.S. EPA, 1992a).
Domestic septage from portable chemical toilet and type
III marine sanitation device wastes can contain 4 to 6
times more total nitrogen than was assumed to derive
the annual application rate formula, however (U.S. EPA,
1993). While not required by the Part 503 regulation, it
is recommended that land appliers consider reducing
the volume applied per acre of such high nitrogen-con-
taining domestic septage (U.S. EPA, 1993). For exam-
ple, if the land owner is expecting to grow a 100-bushel
per acre corn crop and the domestic septage contains
6 times more total nitrogen, the gallons applied should
be reduced 6-fold (from 38,500 to about 6,400 gallons).
For additional guidance on avoiding nitrogen contamina-
tion of ground water when land applying domestic septage
with a high nitrogen content or dewatered domestic sep-
tage, see Domestic Septage Regulatory Guidance: A
Guide to the EPA 503 Rule (U.S. EPA, 1993).
11.2.2 Pathogen Reduction Requirements
Domestic septage must be managed so that pathogens
(disease-causing organisms) are appropriately reduced.
The Part 503 regulation offers two alternatives to meet
this requirement. Pathogen reduction alternative 1 (no
treatment) and restrictions are presented in Figure 11-1
(U.S. EPA, 1993); the requirements of pathogen reduc-
tion alternative 2 (with treatment) are listed in Figure
11-2 (U.S. EPA, 1993). Both of the pathogen reduction
alternatives impose crop harvesting restrictions. Site
access controls and grazing restrictions, however, are
also required when the domestic septage is not treated
(alternative 1 only). Certification that the Part 503 patho-
gen reduction requirement has been met is also required
of the domestic septage land applier, as discussed in
Section 11.2.4 below. Chapter 3 discusses the pathogen
reduction requirements of Part 503 in greater detail.
11.2.3 Vector Attraction Reduction
Requirements
For application of domestic septage to agricultural land,
forests, or reclamation sites, the Part 503 regulation re-
quires that one of the following three options be imple-
mented to reduce vector attraction (U.S. EPA, 1994b):
• Subsurface injection.
• Incorporation (surface application followed by plow-
ing within 6 hrs).
• Alkali stabilization.
131
-------
Domestic septage is land applied without treatment, and the
following restrictions must be observed:
Crop Restrictions:
• Food crops with harvested parts that touch the domestic
septage/soil mixture and are totally above ground shall not
be harvested for 14 months after application of domestic
septage.
• Food crops with harvested parts below the surface of the
land shall not be harvested for either (1) 20 months after
application if domestic septage remains on the land
surface for 4 months or longer, or (2) 38 months after
application if domestic septage remains on the land
surface for less than 4 months, prior to incorporation into
the soil.
• Feed, fiber, and food crops shall not be harvested for 30
days after application of the domestic septage.
• Turf grown on land where domestic septage is applied
shall not be harvested for one year after application of the
domestic septage when the harvested turf is placed on
either a lawn or land with a high potential for public
exposure, unless otherwise specified by the permitting
authority.
Grazing Restrictions:
• Animals shall not be allowed to graze on the land for 30
days after application of domestic septage.
Site Restrictions:
• Public access to land with a low potential for public
exposure shall be restricted for 30 days after application of
domestic septage. Examples of restricted access include
remoteness of site, posting with no trespassing signs,
and/or simple fencing.
Figure 11-1. Part 503 pathogen reduction Alternative 1 for do-
mestic septage (without additional treatment) ap-
plied to agricultural land, forests, or reclamation
sites (U.S. EPA, 1993).
For detailed information on subsurface injection and
incorporation practices at land application sites, see
Chapter 14.
Alkali stabilization of domestic septage involves raising
its pH. Vector attraction is reduced if the pH is raised to
at least 12 through alkali addition and maintained at 12
or higher for 30 minutes without adding more alkali.
When this option is used, every container of domestic
septage must be monitored to demonstrate that it meets
the requirement (U.S. EPA, 1992b). When this is done,
the treatment component of alternative 1 for pathogen
reduction, discussed above, also is met. This vector
attraction reduction requirement is slightly less stringent
than the alkali addition method required by Part 503 for
othertypes of sewage sludge. This option addresses the
practicalities of using or disposing domestic septage,
which is typically treated by lime addition to the domestic
septage hauling truck (see Section 11.3). The treated
septage is typically applied to the land shortly after lime
The pH of the domestic septage is raised to 12 or higher by
the addition of alkali material and, without adding more
alkali, the pH remains at 12 or higher for 30 minutes prior to
being land applied. In addition, the following restrictions
must be observed.
Crop Restrictions:
• Food crops with harvested parts that touch the domestic
septage/soil mixture and are totally above ground shall not
be harvested for 14 months after application of domestic
septage.
• Food crops with harvested parts below the surface of the
land shall not be harvested for either (1) 20 months after
application if domestic septage remains on the land
surface for 4 months or longer, or (2) 38 months after
application if domestic septage remains on the land
surface for less than 4 months, prior to incorporation into
the soil.
• Feed, fiber, and food crops shall not be harvested for 30
days after application of the domestic septage.
Grazing Restrictions: None
Site Restrictions: None
Figure 11-2. Part 503 pathogen reduction Alternative 2 for do-
mestic septage (with pH treatment) applied to ag-
ricultural land, forests, or reclamation sites (U.S.
EPA 1993).
addition. During this very short time interval, the pH is
unlikely to fall to a level at which vector attraction could
occur (U.S. EPA, 1992b).
If a land applier of domestic septage chooses pathogen
reduction alternative 1 (see Figure 11-1), which involves
land application of domestic septage without additional
treatment, the Part 503 rule also requires that one of the
first two vector attraction reduction options listed in Table
11-3 be met (U.S. EPA, 1993). If a land applier chooses
pathogen reduction alternative 2 (pH treatment as de-
scribed in Figure 11-2), he or she must meet the require-
ments of the third vector attraction reduction option
shown in Figure 11-3 (U.S. EPA, 1993).
11.2.4 Certification Requirements for
Pathogen and Vector Attraction
Reduction
The land applier of domestic septage must sign a certi-
fication that the pathogen and vector attraction reduction
requirements of the Part 503 regulation have been met.
The required certification is shown in Figure 11-4. The
certification includes a statement by the land applier that
his or her employees, if any, are qualified and capable
of gathering the needed information and performing the
necessary tasks so that the required pathogen and vec-
tor attraction reduction requirements are met. A person
is qualified if he or she has been sufficiently trained to
do their job correctly.
132
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Vector Attraction Reduction Option 1:
Injection
Domestic septage shall be injected below the surface of the
land, AND no significant amount of the domestic septage
shall be present on the land surface within one hour after
the domestic septage is injected;
Vector Attraction Reduction Option 2:
Incorporation
Domestic septage applied to the land surface shall be
incorporated into the soil surface plow layer within six (6)
hours after application;
or
Vector Attraction Reduction Option 3:
pH Adjustment
The pH of domestic septage shall be raised to 12 or higher
by addition of alkali material and, without the addition of
more alkali material, shall remain at 12 or higher for 30
minutes.
Figure 11-3. Part 503 vector attraction reduction options for
domestic septage applied to agricultural land, for-
ests, or reclamation sites (U.S. EPA, 1993).
11.2.5 Restrictions on Crop Harvesting,
Animal Grazing, and Site Access
As discussed above, the Part 503 regulation for domes-
tic septage application to agricultural land, forests, or
reclamation sites includes various restrictions on the
crops harvested and animals grazed on the site, as well
as access to the site by the public. The requirements
are less restrictive if the domestic septage has been
alkali stabilized. Figures 11-1 and 11-2 summarize crop,
grazing, and public access restrictions for untreated
and alkali-stabilized domestic septage, respectively
(U.S. EPA, 1993). It is recommended that land appliers
of domestic septage inform the owner/operator of the
land where the domestic septage has been applied
about these crop harvesting and site access restriction
requirements.
For more detailed information, see EPAs Domestic
Septage Regulatory Guidance (U.S. EPA, 1993) and 40
CFR Part 503. It is important to note that state regula-
tions may differ and be more restrictive than the re-
quirements outlined in Figures 11-1 and 11-2.
11.2.6 Recordkeeping and Reporting
Records must be kept by a land applier of domestic sep-
tage for five years after any application of domestic sep-
tage to a site, but Part 503 does not require land appliers
of domestic septage to report this information. These re-
quired records might be requested for review at any time
by the permitting or enforcement authority (U.S. EPA,
Certification3
I certify under penalty of law that the pathogen
requirements in [insert pathogen reduction alter-
native 1 or 2] and the vector attraction reduction
requirements in [insert vector reduction alternative
1, 2, or 3] have/have not [circle one] been met.
This determination has been made under my di-
rection and supervision in accordance with the
system designed to ensure that qualified person-
nel properly gather and evaluate the information
used to determine that the pathogen requirements
and the vector attraction reduction requirements
have been met. I am aware that there are signifi-
cant penalties for false certification, including the
possibility of fine and imprisonment.
Signed:
(to be signed by the person designated
as responsible in the firm that applies
domestic septage)
a EPA is proposing changes in the certification language.
Figure 11-4. Certification of pathogen reduction and vector at-
traction requirements (U.S. EPA, 1994b).
1993). The retained records must include the informa-
tion shown in Figure 11-5 and a written certification (see
Figure 11-4). EPAs Domestic Septage Regulatory Guid-
ance (U.S. EPA, 1993) contains examples of ways to
organize record keeping for sites where domestic sep-
tage is land applied.
The location of the site where domestic septage is applied
(either the street address, or the longitude and latitude of
the site, available from U.S. Geological Survey maps).
The number of acres to which domestic septage is applied
at each site.
The date and time of each domestic septage application.
The nitrogen requirement for the crop or vegetation grown
on each site during the year. Also, while not required,
indicating the expected crop yield would help establish the
nitrogen requirement.
The rate (in gallons per acre) at which domestic septage is
applied to the site during the specified 365-day period.
The certification shown in Figure 11-4.
A description of how the pathogen requirements are met
for each volume of domestic septage that is land applied.
A description of how the vector attraction reduction
requirement is met for each volume of domestic septage
that is land applied.
Figure 11-5. Part 503 5-year recordkeeping requirements (U.S.
EPA, 1993).
133
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11.2.7 Part 503 Required Management
Practices
Certain management practices for the land application
of all types of sewage sludge, including domestic sep-
tage, are included in Part 503. These management prac-
tices require that the land application of sewage sludge
and domestic septage does not adversely affect endan-
gered or threatened species; does not take place during
flooded, frozen or snow-covered conditions; and does
not occur within 33 ft (10 m) of wetlands or surface
waters (U.S. EPA, 1994b). For additional information on
these management practices, see Chapter 3.
11.2.8 State Requirements for Domestic
Septage
The Part 503 regulation sets minimum requirements for
land application of domestic septage that must be met in
all states. States may, however, adopt (or continue to
use) regulations that are more stringent than the federal
rule.
State regulations for domestic septage use or disposal
vary widely. In most cases, states require a hauler to
submit for approval use or disposal plans for domestic
septage. Most states also provide recommendations on
how domestic septage should be land applied (U.S.
EPA, 1994b). In addition, states usually issue hauler
licenses, although some states delegate this authority to
counties or other municipal agencies (U.S. EPA, 1994b).
Since promulgation of the Part 503 federal regulation,
many states have reviewed their regulations regard-
ing land application of sewage sludge and domestic
septage. Those states that have regulations less strin-
gent than the federal regulation will likely change state
regulations to meet the minimum federal require-
ments (U.S. EPA, 1994b). For further assistance with
applicable state regulations, contact your state septage
coordinator.
11.3 Adjusting the pH of Domestic
Septage
The Part 503 regulation regarding land application of
domestic septage is less burdensome if alkali stabiliza-
tion is practiced. Stabilization is a treatment method
designed to reduce levels of pathogenic organisms,
lower the potential for putrefaction, and reduce odors.
Stabilization methods for domestic septage are summa-
rized in Table 11-4 (U.S. EPA, 1994a). The simplest and
most economical technique for stabilization of domestic
septage is pH adjustment. Usually, lime is added to
liquid domestic septage in quantities sufficient to in-
crease the pH of the septage to at least 12.0 for 30
minutes (U.S. EPA, 1994b). If the lime is added before
or during pumping of the septic tank, in many cases 30
minutes will elapse before the truck reaches the land
application site. Other stabilization options, such as
aerobic digestion, are relatively simple but have higher
capital and operating costs (U.S. EPA, 1994b), and
cannot be used to meet Part 503 domestic septage
treatment requirements (for application to agricultural
land, forests, or reclamation sites).
To raise the pH of domestic septage to 12 for 30 min-
utes, sufficient alkali (e.g., at a rate of 20 Ib to 25 Ib of
lime [as CaO or quicklime] per 1,000 gal [2.4 kg to 3.6
kg per 1,000 L]) of domestic septage typically is needed,
although septage characteristics and lime requirements
vary widely (U.S. EPA, 1994b). EPA recommends the
following approaches for alkali stabilization prior to land
application (U.S. EPA, 1994b):
• Addition of alkali slurry to the hauler's truck before
the domestic septage is pumped into the truck, with
additional alkali added as necessary after pumping.
• Addition of alkali slurry to the domestic septage as it
is pumped from the septic tank into the hauler's truck.
(Addition of dry alkali to a truck during pumping with
a vacuum pump system is not recommended; dry
alkali will be pulled through the liquid and into the
vacuum pump, causing damage to the pump.)
• Addition of either alkali slurry or dry alkali to a holding
tank containing domestic septage that has been dis-
charged from a pumper truck.
Many states allow domestic septage to be alkali-stabi-
lized within the truck. Some states, however, prohibit
alkali stabilization in the hauler's truck and require a
separate holding/mixing tank where alkali addition and
pH can be easily monitored. A separate holding and
mixing tank is preferred for alkali stabilization for the
following reasons (U.S. EPA, 1994b):
• More rapid and uniform mixing can be achieved.
• A separate holding and mixing tank affords more con-
trol over conditions for handling and metering the
proper quantity of alkali.
• Monitoring of pH is easier, and more representative
samples are likely to be collected due to better mixing.
• Raw domestic septage can be visually inspected.
To prevent damage to vacuum pumps and promote
better mixing of the alkali and domestic septage, alkali
should be added as a slurry (U.S. EPA, 1994b). The
slurry can be added to the truck before pumping the
tank, although the amount of alkali necessary to reach
pH 12 will vary from load to load. Provisions should be
made to carry additional alkali slurry on board the truck
to achieve the necessary dosage (U.S. EPA, 1994b).
Compressed air injection through a coarse-bubble dif-
fuser system is the recommended system for mixing the
contents of a domestic septage holding tank. Mechanical
134
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Table 11-4. Summary of Domestic Septage Stabilization Options (U.S. EPA, 1994b)
Method Description Advantages
Disadvantages
Alkali stabilization3
Aerobic digestion
Anaerobic digestion
Composting
Lime or other alkaline material
is added to liquid domestic
septage to raise pH to 12.0 for
minimum of 30 min.
Domestic septage is aerated for
15 d to 20 d in an open tank to
achieve biological reduction in
organic solids and odor
potential. (Time requirements
increase with lower
temperatures.)
Domestic septage is retained for
15 d to 30 d in an enclosed
vessel to achieve biological
reduction in organic solids.
Liquid domestic septage or
domestic septage solids are
mixed with bulking agent (e.g.,
wood chips, sawdust) and
aerated mechanically or by
turning. Biological activity
generates temperatures
sufficiently high to destroy
pathogens.
Very simple; minimal operator
attention.
Low capital and O&M costs.
Provides temporary reduction in
sulfide odors.
Meets EPA criteria for reduction
in vector attraction.
Reduces EPA site restriction
requirements for land application.
Relatively simple.
Can provide reduction in odors.
Generates methane gas, which
can be used for digester heating
or other purposes.
Final product is potentially
marketable and attractive to
users as soil amendment.
Increases mass of solids
requiring disposal.
Handling of lime may cause
dust problems.
Lime feed and mixing
equipment require regular
maintenance.
High power cost to operate
aeration system.
Large tanks or basins required.
Cold temperatures require much
longer digestion periods.
Requires skilled operator to
maintain process control.
High maintenance requirements
for gas handling equipment.
High capital costs.
Generally not used except for
co-treatment with sewage
sludge.
Costly materials handling
requirement.
Requires skilled operator
process control.
High odor potential.
High operating costs.
Only alkali stabilization meets Part 503 domestic septage treatment requirements.
mixers are not recommended because they often be-
come fouled with rags and other debris present in the
septage (U.S. EPA, 1994b).
Figure 11-6 presents a procedure for alkali-stabilizing
septage within the pumper truck. Methods recom-
mended by domestic septage servicing professionals
are presented in Domestic Septage Regulatory Guid-
ance (U.S. EPA, 1993), along with associated cautions.
If pH adjustment is used for domestic septage, the Part
503 requirements apply to each truckload unless pH
adjustment was done in a separate treatment device
(e.g., lagoon or tank) (U.S. EPA, 1993).
11.3.1 Sampling for pH
Land appliers of domestic septage should not automat-
ically assume that the lime or other alkali material added
to domestic septage and the method of mixing chosen
will adequately increase pH. The pH must be tested. A
representative sample should be taken from the body of
the truckload or tank of domestic septage for testing. For
example, a sampling container could be attached to a rod
or board and dipped into the domestic septage through
the hatch on top of the truck or tank or through a sampling
port (U.S. EPA, 1993). Alternatively, a sample could be
taken from the rear discharge valve at the bottom of the
truck's tank. If the lime has settled to the bottom of the tank,
however, and has not been properly mixed with the do-
mestic septage, the sample will not be representative.
Two separate samples should be taken 30 minutes
apart, and both of the samples must test at pH 12 or
greater (with the pH reading converted to an equivalent
value at 25°C to account for the influence of hot and cold
weather on meter readings). If the pH is not at 12 or
greater for a full 30 minutes, additional alkali can be
added and mixed with the domestic septage. After mix-
ing in the additional alkali, however, the domestic sep-
tage must be at 12 or greater for a full 30 minutes to
meet the pH requirement of the Part 503 regulation
(U.S. EPA, 1993).
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Purpose To raise the pH of domestic septage to 12 for a
minimum of 30 min.
Approach • Add lime slurry in sufficient quantity before
pumping the tanks and add additional slurry as
needed after pumping.
• Add lime slurry in sufficient quantity during
pumping of the tanks by vacuuming slurry
through small suction line fitted to main suction
hose.
Type of lime • Pulverized quicklime (CaO).
• Hydrated lime (Ca(OH)2).
(Less quicklime is required than is hydrated lime
to achieve the same pH, but quicklime is more
corrosive and difficult to handle.)
Dosage Typically 20 Ib to 25 Ib quicklime per 1,000 gal of
domestic septage (or about 26 Ib to 33 Ib of
hydrated lime per 1,000 gal).
Slurry Approximately 80 Ib of pulverized quicklime or
hydrated lime in 50 gal of water. Mix mannually
with paddle in a 55-gal drum or in a 200-gal
polyethylene tank with electric mixer (preferred).
CAUTION: Heat is liberated when quicklime is
added to water. Wear rubber gloves, appropriate
respirator (for dust), and goggles. Add lime slowly
to partially full tank, an emergency eyewash
station should be located nearby.
Application Typically 12 to 15 gal quicklime slurry per 1,000
rate gal of domestic septage (or 15 gal to 20 gal
hydrated lime slurry).
Monitoring After lime slurry has been mixed with domestic
septage, collect sample from top access hatch using
a polyethylene container fastened to a pole. Measure
pH with pH meter at 25°C (or convert reading to
25°C). (pH paper can also be used, but it is more
cumbersome and less accurate.) If the pH is less
than 12, add more slurry. If pH 12 has been reached,
record pH and time. Sample again after 15 min. If the
pH has dropped below 12, add more lime. The pH
must remain at 12 for at least 30 min. Sample and
record pH prior to applying septage to the land.
Figure 11-6. Procedure for lime-stabilizing domestic septage
within the pumper truck (U.S. EPA, 1994b).
11.4 Methods of Application
The most common, and usually most economical,
method for using or disposing domestic septage is land
application (e.g., land spreading, irrigation, incorpora-
tion). Various options for land applying domestic sep-
tage are summarized in Table 11-5 (U.S. EPA, 1994b).
The simplest application method involves a hauler truck
applying domestic septage by opening a valve and driv-
ing across the land application site. A splash plate or
spreader plate improves domestic septage distribution
onto the soil surface. The domestic septage should be
discharged through a simple screen or basket located
on the truck between the outlet pipe and the spreader
plate. This screen prevents nondegradable materials
such as plastics and other objectionable trash from
being applied to the soil. A simple box screen can be
fabricated from expanded metal. Collected trash should
be lime-stabilized and sent to a sanitary landfill. The
domestic septage must be lime-stabilized prior to sur-
face application, injected below the surface, or plowed
into the soil within 6 hours of application to meet federal
Part 503 requirements for vector attraction reduction
(U.S. EPA, 1994b).
While relatively easy, the application method described
above also is the least flexible and is difficult to control
from a management perspective. In addition, soil may
become compacted, and trucks not designed for off-
road use may have difficulty driving on the site. Small,
rural land application operations where little environ-
mental or human health risk is likely to occur, however,
may find this approach acceptable. A transfer or storage
tank must be available when sites are inaccessible due
to soil, site, or crop conditions (U.S. EPA, 1994b).
Another common approach is to use a manure spreader
or a special liquid-waste application vehicle that re-
moves screened domestic septage from a holding tank
and spreads it on or injects it below the soil surface. If
the domestic septage is incorporated into the soil by
plowing or is injected, pH adjustment may not be
required to meet the Part 503 vector attraction reduc-
tion requirements (U.S. EPA, 1994b). If pH adjustment
is done, this also meets some of the Part 503 require-
ments for pathogen reduction. Figure 11-7 illustrates
a subsurface injection device that injects either a wide
band or several narrow bands of domestic septage
into a cavity 10-15 cm (4 to 6 in) below the soil surface
(U.S. EPA, 1980).
A third approach is to pretreat the domestic septage
(with a minimum of screening) during discharge into a
holding/mixing tank by adding lime and stabilizing it to
pH 12 for 30 min, and then to spray the domestic sep-
tage onto the land surface using commercially available
application equipment. Adjustment of pH reduces odors
and eliminates the need to incorporate the domestic
septage into the soil (U.S. EPA, 1994b).
Cross-Section/Sub-Surface
Injection Process
Injector Shank
and Hose
initial Injection
Cavity
Ultimate Dispersion
Area Alter Injection
Figure 11-7. Subsurface soil injection (Cooper and Rezek,
1980).
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Table 11-5. Summary of Land Application Methods for Domestic Septage (U.S. EPA, 1994b)
Method Description Advantages Disadvantages
Surface Application (for all surface application methods, domestic septage must be incorporated into soil within 6 hrs if the pH is
not adjusted and if the septage is applied to agricultural land, forest, or a reclamation site.)
Spray irrigation
Ridge and furrow
irrigation
Hauler truck
spreading
Farm tractor and
wagon spreading
Pretreated (e.g., screened)
domestic septage is pumped
through nozzles and sprayed
directly onto land.
Pretreated domestic septage is
applied directly to furrows.
Domestic septage is applied to
soil directly from hauler truck
using a splash plate to improve
distribution.
Domestic septage is transferred
to farm equipment for spreading.
Can be used on steep or rough
land.
Minimizes disturbance of soil by
trucks.
Lower power requirements and
odor potential than spray
irrigation.
Same truck can be used for
transport and disposal.
Increases opportunities for
application compared to hauler
truck spreading.
Large land area required.
High odor potential during application.
Storage tank or lagoon required during
periods of wet or frozen ground.
Potential for nozzle plugging.
Limited to 0.5% to 1.50% slopes.
Storage lagoon required.
High odor potential during and
immediately after spreading.
Storage tank or lagoon required during wet
or freezing conditions.
Slope may limit vehicle operation.
Hauler truck access limited by soil
moisture; truck weight causes soil
compaction.
High odor potential during and
immediately after spreading.
Storage tank or lagoon required.
Requires additional equipment (tractor and
wagon).
Subsurface Incorporation
Tank truck or
farm tractor with
plow and furrow
cover
Subsurface
injection
Liquid domestic septage is
discharged from tank into furrow
ahead of single plow and is
covered by second plow.
Liquid domestic septage is
placed in narrow opening
created by tillage tool.
Minimal odor and vector
attraction potential compared
with surface application.
Satisfies EPA criteria for
reduction of vector attraction.
Minimal odor and vector
attraction potential compared
with surface application.
Satisfies EPA criteria for
reduction of vector attraction.
Slope may limit vehicle operation.
Storage tank or lagoon required during
periods of wet or frozen ground.
Slope may limit vehicle operation.
Specialized equipment and vehicle may be
costly to purchase, operate, and maintain.
Storage tank or lagoon required during wet
or frozen conditions.
11.5 Operation and Maintenance at Land
Application Sites Using Domestic
Septage
Key elements of a successful operation and mainte-
nance program for a domestic septage land application
site include (U.S. EPA, 1994b):
• Provision of receiving and holding facilities for the do-
mestic septage to provide operational flexibility (optional).
• Proper domestic septage treatment prior to applica-
tion as required to meet federal and state regulations
(need for treatment depends on requirements of ap-
plication method).
• Control of domestic septage application rates and
conditions in accordance with federal and state rules.
• Proper operation and maintenance of the application
equipment.
• Monitoring of domestic septage volumes and charac-
teristics, as well as soil, plant, surface water and ground
water as required by federal and state regulations.
• Odor control.
• Good recordkeeping and retention of records for at
least 5 years.
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Odor problems should not arise at a site where domestic
septage is land applied if the requirements of Part 503
are followed. A well-managed operation that uses pH
adjustment and practices subsurface injection or sur-
face application/incorporation at or below agronomic
rates (see Section 11.2.1.1) will create minimal odor
emissions. Additional guidelines for minimizing odor
problems at land application sites are presented in
EPAs Guide to Septage Treatment and Disposal (U.S.
EPA, 1994b).
Operation and maintenance requirements for land appli-
cation of domestic septage vary widely depending on
the application technique and the type of equipment used.
11.6 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
U.S. EPA. 1994a. A plain English guide to the Part 503 biosolids rule.
EPA/832/R-93/003. Washington, DC.
U.S. EPA. 1994b. Guide to septage treatment and disposal. EPA/625/
R-94/002. Cincinnati, OH.
U.S. EPA. 1993. Domestic septage regulatory guidance: A guide to
the Part 503 rule. EPA/832/B-92/005. Washington, DC.
U.S. EPA. 1992a. Technical support document for land application of
sewage sludge. EPA/822/R-93/001a (NTIS PB93110583). Wash-
ington, DC.
U.S. EPA. 1992b. Environmental regulations and technology: Control
of pathogens and vector attraction in sewage sludge. EPA/625/R-
92/013. Washington, DC.
U.S. EPA. 1980. Septage management. EPA/600/8-80/032. (NTIS PB
81142481). Washington, DC.
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Chapter 12
Public Participation
12.1 Introduction
A critical factor in establishing a sewage sludge land
application program in most communities is the partici-
pation of local citizens from the beginning and at various
key stages of the project's development. If not given the
opportunity to discuss their concerns, whether based on
legitimate issues or misperceptions, resistance from
members of the community can significantly complicate
a project and result in additional costs. Moreover, if the
public's viewpoint is ignored until late in the planning
process, opposition within the community may solidify
and be difficult to overcome. Thus, public participation
is as important a factor as any technical consideration
in establishing a sewage sludge land application system
(Lue-Hing et al., 1992). Public involvement in the deci-
sion-making process will help to minimize opposition
and to identify the major barriers to local acceptance
(U.S. EPA, 1984).
A sewage sludge land application project has the best
chance of gaining public acceptance if a public out-
reach effort is organized to stress the demonstrated
value of sewage sludge as a resource. Once accep-
tance has been achieved, it is most likely to be main-
tained through conscientious management of the site
during operations.
In general, the public's willingness to participate in—and
ultimately accept—the siting of a sewage sludge land
application site will depend on:
• An understanding of the need for the project regard-
ing its costs and benefits.
• A sense of confidence that the project will adequately
protect public health and safeguard the environment.
• Encouragement of active public involvement in pro-
ject development so that local interests can be fac-
tored into the plan.
Planning for public participation in the siting of a sewage
sludge land application site involves careful and early
evaluation of what should be communicated, to whom,
by whom, and when. This chapter summarizes the major
considerations for implementing a successful public par-
ticipation program, including the objectives and value of
a public participation, the design and timing of a pro-
gram, and topics generally of public concern regarding
the land application of sewage sludge.
12.2 Objectives
The objectives of a public participation program are:
• Promoting a full and accurate public understanding
of the advantages and disadvantages of land appli-
cation of sewage sludge.
• Keeping the public well-informed about the status of
the various planning, design, and operation aspects
of the project.
• Soliciting opinions, perceptions, and suggestions
from concerned citizens involving the land application
of sewage sludge.
The key to achieving these objectives is to establish
continuous two-way communication between the public
and the land application site planners, engineers, and
eventual operators (Canter, 1977). Officials need to
avoid the common assumption that educational and
other one-way communication techniques will promote
adequate dialogue. A public participation plan should
focus generally on moving people from the typical reac-
tive response to sewage sludge issues to an informed
response about sludge management (Lue-Hing et al.,
1992).
To generate meaningful public participation in the deci-
sion-making process, the public agency or engineering
firm directing the project needs to take particular steps
at each stage of project development (see Section 12.3).
The additional effort involved in soliciting community
input for establishing a land application site should be
considered when making an initial determination about
the best approach for managing the community's sew-
age sludge.
12.3 Implementation of a Public
Participation Program
A program for soliciting public participation in the siting
of a sewage sludge land application site should be
tailored to fit the scale and costs of the particular project.
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Nonetheless, a basic framework for a program that
would be applicable for most situations includes:
• The initial planning stage
• The site selection stage
• The site design stage
• The site preparation and operation stage
These four stages are described below. Beyond this
basic framework, officials should use a common-sense
approach for determining the extent of the public partici-
pation program and the frequency at which public input
should be solicited. When time and money are con-
straining factors, officials will need to concentrate re-
sources on the most effective mechanisms for community
involvement (see Table 12-1). Regardless of its scope,
however, the public participation program will need to be
flexible enough to accommodate various issues that can
arise in the course of establishing a sewage sludge land
application site.
Table 12-1. Relative Effectiveness of Public Participation
Techniques
Communication Characteristics
Public Participation
Technique
Public hearings
Public meetings
Advisory Committee
meetings
Mailings
Contact persons
Newspaper articles
News releases
Audiovisual
presentations
Newspaper
advertisements
Posters, brochures,
displays
Workshops
Radio talk shows
Tours/field trips
Ombudsman
Task force
Telephone line
Level of
Public
Contact
Achieved
M
M
L
M
L
H
H
M
H
H
L
H
L
L
L
H
Ability to
Handle Degree of
Specific Two-Way
Interest Communication
L
L
H
M
H
L
L
L
L
L
H
M
H
H
H
M
L
M
H
L
H
L
L
L
L
L
H
H
H
H
H
M
L = low value
M = medium value
H = high value
12.3.1 Initial Planning Stage
12.3.1.1 Establishing an Advisory Committee
During the initial planning stage, the scope and scale of
the public participation program is decided, and imple-
mentation of the program is then initiated. To facilitate
and follow through with this effort, officials in charge of
the land application project should organize an advisory
committee made up of members of the community. The
committee should include, for example, representatives
of local government, community organizations, and area
businesses (Table 12-2). Since in rural communities the
acceptance of local farmers is particularly important for
a proposed land application program, this group should
also be represented on the committee where appropri-
ate (see Section 12.4.1). The Soil Conservation Service,
county Extension Agents, and Farm Bureau can provide
vital links with the farming community (U.S. EPA, 1984).
The primary responsibility of the advisory committee
should be to organize the community's involvement in
project planning. The overall strategy for informing the
community about the land application project and re-
sponding to concerns should be put in writing. Addition-
ally, the committee could be called upon to provide initial
Table 12-2. Potential Advisory Committee Members (Canter,
1977)
The following groups and individuals should be contacted
about serving on the advisory committee:
• Local elected officials.
• State and local government agencies, including planning
commissions, councils of government, and individual agencies.
• State and local public works personnel.
• Conservation/environmental groups.
• Business and industrial groups, including chambers of commerce
and selected trade and industrial associations.
• Property owners and users of proposed sites and neighboring
areas.
• Service clubs and civic organizations, such as the League of
Women Voters.
• The media, including newspapers, radio, and television.
The following groups should also be contacted, where
appropriate:
• State elected officials.
• Federal agencies.
• Farm organizations.
• Educational institutions, including universities, high schools, and
vocational schools.
• Professional groups and organizations.
• Other groups and organizations, such as urban groups, economic
opportunity groups, political clubs and associations.
• Labor unions.
• Key individuals who do not express their preferences through, or
participate in, any groups or organizations.
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feedback on various project proposals and to function
generally as a liaison between the project staff and the
community at large. In its role as liaison, an advisory
committee would be responsible for receiving commu-
nity input and obtaining responses to questions. A useful
practice in this regard is to keep a log of requests for
information and responses given. For especially large
projects, it might be feasible to hire a public information
professional to assist in this capacity.
When making its assessment about the appropriate ex-
tent of the public outreach effort, the advisory commit-
tee's planning should address when and how often to
use particular mechanisms for encouraging participation
in the land application project. The two general types of
program mechanisms are:
• Educational. Those that allow project staff to present
information to members of the community.
• Interactive. Those that are intended to solicit input
from members of the community.
Throughout the public participation program, the advi-
sory committee should be developing its mailing and
telephone lists. Such lists, which should be continually
updated and expanded by capturing the names of citi-
zens who attend public meetings or otherwise make
contact with the committee, can prove indispensable for
keeping the community involved in the land application
project. Contact by mail and telephone can be used to
alert the community to meetings and developments, or
to provide followup information to citizens who have
expressed particular concerns about the project.
12.3.1.2 Educating the Community
After establishing an advisory committee, the next step
in program implementation is to undertake a public edu-
cation campaign, which typically is kicked off at a well-
publicized public meeting or at a series of meetings
targeted for specific groups within the community.
The level of interest in waste management issues for
most people is fairly low. Thus, while members of the
community at large should be targeted by the public
education campaign, it is particularly important to reach
members of environmental groups, the media, and
elected officials. The participation of such members of
the community is important because they are likely to
have broad affiliations and the ability to affect public
opinion on a large scale (WEF, 1992).
At a public meeting it is important to present general
information about the land application project and to
encourage the community to take an active interest in
the project's development. Presenters at this meeting
might include project staff and engineering consultants.
The meeting is also a good opportunity to introduce the
members of the advisory committee—stressing the
breadth of representation from the various sectors of the
community—and explain the committee's role. Informa-
tion about the project presented at the community meet-
ing should cover:
• The need for the land application program.
• The reason for selecting land application over other
approaches for managing sewage sludge, such as
surface disposal or incineration.
• The use of crops or other vegetation grown on the site.
• The general costs associated with design, construc-
tion, and operation of the program.
• The potential economic incentives, such as job crea-
tion and stimulation of the local economy.
• The program's general design and operation principles.
It may be useful to supplement presentations given at
the meeting with handouts that provide, for instance, a
brief explanation of sewage sludge and how it is gener-
ated; a nontechnical summary of the Part 503 rule; the
professional experience of engineers and others design-
ing the land application program; and a list project con-
tacts. Video support, if available, might also be useful
for providing additional general information at the
meeting.
A community's specific concerns, particularly about pro-
tecting public health and safeguarding the environment,
can be enough to undermine a technically strong plan
for establishing a land application operation. Thus, it is
advisable to make information available about how land
application programs operating over long periods (e.g.,
10 years or more) in other communities have addressed
these concerns (Jacobs et al., 1993).
Once the sewage sludge land application project has
been introduced at a public meeting to interested mem-
bers of the community, informational outreach to the
general public can be achieved primarily through the
local media. Since public meetings are ineffective infor-
mation outlets for certain segments of any community,
however, the outreach effort should include placing paid
advertisements, if feasible, as well as encouraging the
media contacts made at the public meeting to report on
the project. At some point after providing the media with
general information about the proposed land application
site, it may be useful to develop a press kit for distribu-
tion. Providing project-specific information to the media
will increase the accuracy of information reported to the
public (Lue-Hing et al., 1992).
The more types of media that are used to promote the
project, the greater the likelihood of a successful out-
reach effort. For example, a variety of media could be
used as follows:
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• Newspapers reports. A series of articles on land ap-
plication of sewage sludge could be timed to appear
throughout the project to sustain public interest. Also,
occasional news releases would keep the community
informed about developments.
• Television reports. At a minimum, it should be possi-
ble to arrange for coverage of milestone project de-
velopments. It also might be possible to interest news
producers in developing a series about the project.
• Newspaper, television, and radio advertisements. In-
formational advertisements can be used to publicize
critical information about the project. Although televi-
sion advertising tends to be expensive, it can be
particularly effective for reaching a majority of the
community. Radio advertising, especially if broadcast
during the morning or afternoon commute, can be
equally effective while less expensive.
• Public service announcements and editorials. Radio
and television stations are required to offer a limited
amount of broadcast time for airing announcements
or editorials of general interest in the local area. Ca-
ble television stations may have specific program-
ming devoted to local issues. Also, newspapers may
welcome an informed opinion piece for the op-ed page.
Posters, brochures, and displays also can be highly
effective educational tools, especially when designed
creatively and placed in high-traffic areas or given wide
distribution.
12.3.1.3 Soliciting Community Input and
Addressing Concerns
After the public has been generally informed about the
sewage sludge land application project, the advisory
committee should begin concentrating its efforts on so-
liciting community input on the project plan. For this
phase of the public participation program, various types
of forums can be useful for focusing on and responding
to the community's concerns about the project. Con-
cerns that are likely to surface include:
• Public safety and health. As noted above, this issue
can be of primary interest to the community. Thus, it
is important to emphasize the extensive research on
risk assessment and environmental impacts that
serves as the basis for the Part 503 rule. Also, pro-
ject-specific management systems should be ex-
plained. In particular, the community may need to be
reassured that a system has been developed for
avoiding spills of sewage sludge during transport.
• Contamination of water supplies. The public generally
has developed a heightened awareness about water
quality issues. As a result, the public is better pre-
pared to raise water quality issues and to consider
measures taken to safeguard water supplies. The
community should be made aware that Part 503 spe-
cifically addresses protection of ground water and
surface waters by, for instance, restricting runoff from
application sites and limiting the potential for leaching
of pollutants into ground water.
• Accumulation of heavy metals and toxics. The public
may be inclined to assume that sewage sludge is
associated with excessive contaminants, since
"waste" is synonymous with "toxic" in many people's
minds (Lue-Hing et al., 1992). Thus, public informa-
tion efforts should stress the proven beneficial char-
acteristics of sewage sludge and explain the
regulatory limits on the loadings of 10 heavy metals
associated with sewage sludge.
• Regulatory compliance. The community is likely to
question whether the site will be monitored by public
officials for regulatory compliance. This concern can
be addressed by explaining the role of the permitting
authority in enforcing the Part 503 rule and by review-
ing the legal recourse available to officials (e.g., fines
of up to $25,000 per day for a single violation).
• Odor, noise, dust, and traffic. Because odors are usu-
ally the first cause of complaints when a land appli-
cation site is sited near a residential area, sewage
sludge at such sites should be injected or disked into
the soil immediately following application (Jacobs et
al., 1993). The site management plan should specifi-
cally cover such measures, as well as measures to
control noise and dust from the operation of machin-
ery and limit traffic in and out of the site.
• Land values. The community is likely to be concerned
about the impact of the land application operation on
real estate values. This issue should be investigated
and the community should be informed of any poten-
tial for a drop in values. Regarding this and other
concerns, it may be useful to cite the experience of
other communities with a land application program
(Jacobs et al., 1993).
Both formal and informal approaches can be effective
for soliciting and then responding to the community's
concern about the land application project. Regardless
of the forum, however, it is essential that advantages as
well as disadvantages be addressed openly. When there
is a void of information, it is likely to get filled with
distorted portrayals based on assumptions and emotion.
It is far better to fill that void with factual information
(Lue-Hing et al., 1992).
Forums that can be effective for public participation
include meetings and workshops, as well as site tours
that include demonstrations. The appropriateness of a
particular forum will depend on the stage of the project's
development.
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12.3.2 Site Selection Stage
The site selection process involves screening an array
of potential locations for the land application facility,
followed by detailed field investigations that include
water and soil sampling at a handful of candidate sites.
Once the project staff has narrowed the choices down
to a few sites and gathered a reasonable amount of
comparative data, the public should be brought into the
process.
Depending on the scope of the project and the location
of candidate sites relative to population density, the
appropriate forum for public participation at this stage
would be a targeted meeting or a workshop gathering.
If a site close to a residential area is being seriously
considered, neighboring residents will have a vested
interest in selection and want detailed information about
such issues as public safety, odor control, and impact
on land values. Indeed, project staff may need to antici-
pate vocal, organized resistance to the site. Meeting
with interested parties in smaller groups can be an
effective means of diffusing such emotionally loaded
issues. Targeted meetings and workshops have particu-
lar characteristics that are advantageous at this stage of
project development:
• Targeted meetings. Meeting with members of the
community who have a particular interest in the pro-
ject can be an efficient means of addressing site-spe-
cific concerns. A useful approach is to give the
community an opportunity to discuss issues directly
with project engineers, the prospective site manager,
and members of the advisory committee. These
smaller meetings should be less structured than the
initial, community-wide meeting so that dialogue can
be encouraged. A sketchy outline should be used
primarily to elicit a group's concerns, and the project
staff should be fully prepared to respond to a range
of issues.
• Workshops. When working with a group that is par-
ticularly interested in site-selection criteria, such as
an environmental group or the media, a workshop is
a useful forum for presenting and discussing informa-
tion. A fairly structured agenda is appropriate for a
workshop, as long as sufficient time is scheduled for
open discussion. If a workshop is effective, partici-
pants are likely to disseminate the information more
broadly within the community.
To generate participation in these more focused gather-
ings, the advisory committee might want to use its tele-
phone and mailing lists to contact potentially interested
individuals. Otherwise, opposition to the site finally se-
lected could surface late in the process, when it may be
less readily diffused. Forthe same reason, it is important
to keep the community involved through completion of
the selection process.
When opposition to the developing plan does arise, it is
best to meet it head on. Recommended presentation
tactics (Lue-Hing et al., 1992) include:
• Answer all questions candidly and publicly.
• Avoid arguing over emotionally charged questions;
emphasize generalities.
• Never reiterate incorrect information, either verbally
or in print.
12.3.3 Site Design Stage
Because the relevant information at this stage of the
project is of a particularly technical nature, community
interest will be less broad-based. Nonetheless, it is im-
portant to maintain some degree of public participation.
This challenge is likely to fall to the advisory committee,
which should consider various and innovative ap-
proaches for reaching the public with design informa-
tion. Suggested approaches include:
• Field trips. A visit to a nearby operating land applica-
tion site can be a useful means of informing special
interest groups about design considerations. A project
engineer should accompany the group on the visit so
that the host site can be compared to the planned
site.
• Video presentations. If available, a general video that
explains site design in regard to eventual operation
can be an effective means of involving the community
in the project's design stage. The video could be
screened for small groups and followed by a question
and answer period with project staff.
• Task forces. Assigning members of the community to
design-related tasks that address specific public con-
cerns can generate important input for design plan-
ning. To be most effective, task force members
should have a technical orientation.
• Media campaign. Information (e.g., press releases)
should be provided to the media as design mile-
stones are reached. A guest appearance on a radio
call-in program or a cable news program by a project
spokesperson might also be effective at this stage if
it can be arranged.
Once the design for the land application site is final, it
will need to be formally presented to the community at
a public hearing. Such gatherings are often legally re-
quired, must be preceded by published notification to the
community, and follow a set agenda. Also, relevant ma-
terials might need to be made available for public review
prior to the hearing. The agenda for a public hearing
usually includes presentations by project staff, after
which the floor is opened for comments from the com-
munity. The effectiveness of the gathering can be en-
hanced when an elected official or other prominent,
143
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informed figure in the community chairs the hearing or
at least participates.
12.3.4 Site Preparation and Operation Stage
While the selected land application site is being pre-
pared for operations, the advisory committee should
monitor activity at the site and maintain contact with the
community. This is particularly important if buildings or
treatment structures are being constructed, since the
delivery of materials and operation of heavy equipment
can create nuisances, especially for local residents.
Committee members should be prepared to respond to
complaints as they arise, either on their own or with the
help of the project staff. If feasible, the project staff
should assign an ombudsman to resolve issues that
arise during site preparation and to continue in this
capacity, at least initially, once operations are underway.
Once fully operational, the site should continue to be
monitored for its actual or potential negative impacts on
the community. After an initial period of operation, the
advisory committee may want to conduct a limited tele-
phone survey to gauge how the public is feeling about
the site. The committee would then report results to the
operations staff and follow up to see that any necessary
modifications have been made. For example, better
odor control practices may need to be adopted, or site
traffic may need to be restricted to specified hours.
After the advisory committee has determined that the
land application site has been generally accepted by the
community, it should provide followup information to the
media. This is the appropriate point to promote the
success of the site and its advantages to the commu-
nity—not the least of which should be the beneficial use
of locally generated sewage sludge. For instance, the
community should be interested in learning about the
use of crops grown on the site and whether local gar-
deners are land applying sewage sludge.
12.4 Special Considerations
12.4.1 Agricultural Sites
Implementation of an agricultural land application pro-
ject for sewage sludge can require acceptance and
approval by local officials, farmers, landowners, and
other affected parties. Public resistance to agricultural
land application of sewage sludge can stem from fear
that the sludge may contain concentrations of organic or
inorganic substances that could be toxic to plants or
accumulate in animals or humans consuming crops
grown on sludge-treated lands.
The most critical aspect of a public participation program
in such cases is securing the involvement of farmers
who will use the sludge. How this involvement is to
be secured during the planning process depends on
the individual communities involved; their past experi-
ences with land application systems; overall public
acceptance of the concept; and the extent to which
related or tangential environmental concerns are voiced
in the community.
Generally, a low-key approach is most effective. The
various approaches can consist of one or more of the
following steps:
• Check with the wastewater treatment operator to see
if any local farmers have requested sewage sludge
in the past.
• Have the local Soil Conservation Service or Agricul-
tural Extension Service agent poll various individuals
in the area.
• Describe the project in the local newspaper, asking
interested parties to contact the extension agent.
• Personally visit the identified parties and solicit their
participation. A telephone contact will elicit little sup-
port unless followed by a personal visit.
The use of demonstration plots is very effective in pro-
moting the land application of sewage sludge by farm-
ers. If farmers can compare crops grown on sludge-treated
soil with these grown with conventional fertilizer, their will-
ingness to use sewage sludge will increase markedly
(Miller et al., 1981). The following questions regarding
sewage sludge land application need to be discussed
with landowners:
• How long is the landowner willing to participate (e.g.,
a trial period of 1 or more years; open-ended partici-
pation; until one or both parties decide to quit; for a
prescribed period of time)?
• What crops are traditionally planted, and what is the
usual crop rotation?
• If the sewage sludge characteristics were such that
a different crop is desirable, would the landowner be
willing to plant that crop?
• Which fields would be included in the sewage sludge
land application program?
• Under what conditions would the landowner accept
the sewage sludge, what time of the year, and in what
quantities?
• Is the landowner willing to pay a nominal fee for the
sewage sludge, accept it free of charge, or must the
municipality pay the landowner for accepting sludge?
• Is the landowner willing to engage in special proce-
dures (e.g., maintaining soil pH at 6.5 or greater)?
The public participation program should emphasize both
the benefits and the potential problems of applying sew-
age sludge on cropland.
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Forest Sites
12.4.3 Reclamation Sites
To help achieve acceptance, a program for the land
application of sewage sludge at a forest site should
satisfactorily address the following questions:
• How will public access be controlled in the application
area for an appropriate period (normally 12 to 18
months) after sewage sludge application? Forested
areas are often used for various recreational activities
(e.g., picnicking, hiking, gathering of forest products).
Even privately owned forest land often is viewed by
the public as accessible for these purposes. The
owner of the land, private or public, will have to agree
to a method for controlling public access (e.g., fence,
chain with signs). The public, through its representatives,
must agree to restrictions if the land is publicly owned.
• Will public water supplies and recreational water re-
sources be adequately protected against contamina-
tion? This concern should be covered by proper
siting, system design, and monitoring. Public health
authorities and regulatory agencies must be satisfied
and involved in the public participation program.
Careful consideration must be given to municipal wa-
tersheds and/or drinking water recharge areas to
avoid contamination.
• Will the applied sewage sludge cause adverse effects
to the existing or future trees in the application area?
Based on the available data from research and dem-
onstration projects, many tree species, with few
exceptions, respond positively to sewage sludge
application, provided the sludge is not abnormally high
in detrimental constituents and proper management
practices are followed.
• Unlike most agricultural applications, there is much
less concern about possible food chain transmission
of contaminants to humans. The consumption of wild
animals by hunters and their families will occur, but
there is little potential for contamination of meat from
such animals through contact with a properly man-
aged sludge application area.
Prior to the initiation of any reclamation project using
sewage sludge, it will likely be necessary to educate the
public to gain public acceptability. The task may be
difficult with lands disturbed by mining, because local
opposition to mining activity already exists in many
cases. This is particularly true if the mining activity has
already created some adverse environmental problems,
such as reduced local ground-water quality, acid mine
drainage, or serious soil erosion and sedimentation of
local streams.
Citizens, regulatory agencies, and affected private busi-
ness entities need to participate in the planning process
from the beginning. The most effective results are usu-
ally achieved when industry, citizens, planners, elected
officials, and state and federal agencies share their
experience, knowledge, and goals, and jointly create a
plan acceptable to all.
12.5 References
Canter, L. 1977. Environmental impact assessment. New York, NY:
McGraw-Hill, pp. 221, 222.
Jacobs, L., S. Carr, S. Bb'hm, and J. Stukenberg. 1993. Document
long-term experience of biosolids land application programs. Pro-
ject 91-ISP-4, Water Environment Research Foundation, Alexan-
dria, VA.
Lue-Hing, C., D. Zenz, R. Kuchenrither, eds. 1992. Municipal sewage
sludge management: Processing, utilization and disposal, Ch. 12.
In: Water quality management library, Vol. 4. Lancaster, PA: Tech-
nomic Publishing.
Miller, R., T. Logan, D. Forester, and D. White. 1981. Factors contrib-
uting to the success of land application programs for municipal
sewage sludge: The Ohio experience. Presented at the Water
Pollution Control Federation Annual Conference, Detroit, Ml.
U.S. EPA. 1984. Environmental regulations and technology: Use and
disposal of municipal wastewater sludge. EPA/625/10-84/003.
Washington, DC.
WEF. 1992. Proceedings of the future direction of municipal sludge
(biosolids) management: Where we are and where we're going,
Vol. 1, Portland, OR, July 26-30, 1992. Water Environment Fed-
eration, Alexandria, VA. No. TT041.
145
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Chapter 13
Monitoring and Sampling
13.1 Overview
The Part 503 rule requires monitoring of sewage sludge
that is land applied for metal concentrations, pathogen
densities, and vector attraction reduction. In addition,
soil testing for nutrients (N, P, and K) may be useful at
land application sites to help determine plant nutrient
needs. Additional monitoring (e.g., of water quality and
vegetation) is not required by Part 503 for land applica-
tion sites because the rule protects these resources
through pollutant limits, management practices, patho-
gen reduction requirements, etc.
This chapter discusses Part 503 monitoring require-
ments for sewage sludge, including required analytical
methods, and specifies sampling procedures that might
be particularly useful for characterizing sewage sludge
(Section 13.2). Soil monitoring and sampling methods
for relevant parameters also are presented (Section
13.3). Brief discussions of surface water, ground-water,
and vegetation monitoring are included in Sections 13.4
and 13.5. Monitoring and sampling concerns particular
to reclamation sites are discussed in Section 13.6.
State regulatory programs may have specific requirements
for monitoring sewage sludge land application sites. The
appropriate regulatory agencies should be contacted to
identify any applicable monitoring requirements.
13.2 Sewage Sludge Monitoring and
Sampling
The Part 503 requirements related to monitoring for
sewage sludge that is land applied focus primarily on
sewage sludge characterization to determine pollutant
concentration, pathogen density, and vector attraction
reduction. Required monitoring includes:
• Monitoring of sewage sludge for 10 pollutants (As,
Cd, Cr, Cu, Pb, Hg, Mo, Ni, Se, and Zn) to determine
pollutant levels in sewage sludge, compared to Part
503 pollutant limits (see Chapter 3).
• Monitoring to determine pathogen densities in sew-
age sludge, as described in Chapter 3.
• Monitoring to ensure that conditions for vector attrac-
tion reduction are maintained.
Table 13-1 summarizes major considerations for moni-
toring metals, pathogens, and vector attraction reduc-
tion in sewage sludge. Another EPA document,
Environmental Regulations and Technology: Control of
Pathogens and Vector Attraction in Sewage Sludge
(U.S. EPA, 1992), provides guidance for the monitoring,
sampling, and analysis of pathogens and vector attrac-
tion reduction efforts under Part 503 in detail and should
be consulted for further guidance. The remainder of this
section focuses on sampling and analysis of sewage
sludge for pollutants. For additional guidance on monitor-
ing of sewage sludge for land application, see EPAs Pre-
paring Sewage Sludge for Land Application or Surface
Disposal: A Guide forPreparers of Sewage Sludge on the
Monitoring, Record Keeping, and Reporting Requirements
of the Federal Standards for the Use or Disposal of Sew-
age Sludge, 40 CFR Part 503 (U.S. EPA, 1993).
13.2.1 Sampling Location
Sewage sludge samples must be representative of the
final sewage sludge that is land applied. To achieve this
goal, samples must be representative of the entire
amount of sewage sludge being sampled, collected after
the last treatment process, and taken from the same,
correct location each time monitoring is performed.
Sampling locations should be as close as possible to the
stage before final land application. Liquid sewage
sludge can be sampled at the wastewater treatment
plant from pipelines, preflushed pipeline ports, or la-
goons. Dewatered sewage sludge can be sampled at a
wastewater treatment plant from conveyors, front-end
loaders moving a pile of sewage sludge, or during truck
loading or unloading. At a land application site, dewa-
tered samples can also be taken on the ground after
unloading but preferably before application, or possibly
after spreading.1 Table 13-2 identifies recommended
sampling points for various types of sewage sludge.
1 Sampling after spreading poses the risk of penalties if samples
exceed Part 503 pollutant limits and pathogen densities or do not
comply with the regulation's vector attraction reduction require-
ments. Sampling after spreading should only be done if parameters
of concern do not vary greatly in concentration and are known to fall
well below Part 503 limits.
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Table 13-1. Monitoring Considerations for Part 503 Requirements
Parameter Validity of Analytical Data Over Time and When Sampling/Analysis Must Occur
Metals
Metals
Data remain valid.
Determine monitoring frequency in accordance with monitoring frequency requirements.
Pathogens Class A
Applies to All Class A Pathogen
Reduction Alternatives (PRA):
Fecal Coliform & Salmonella sp.
Because regrowth of fecal coliform and Salmonella sp. can occur, monitoring should be done:
(a) at the time of use or disposal, or,
(b) when sewage sludge is prepared for sale or give-away in a bag or other container for land
application, or
(c) when sewage sludge is prepared to meet EQ requirements.
Additional Information on Each Class A Pathogen Category
Class A PRA 1:
Thermal Treatment, Moisture,
Particle Size & Time Dependent
Class A PRA 2:
High pH, High Temperature
Class A PRA 3:
Enteric Virus & Viable Helminth
Ova to Establish Process
Class A PRA 4:
Enteric Virus & Viable Helminth
Ova for Unknown Process
Class A PRA 5:
PFRP
Class A PRA 6:
PFRP Equivalent
Data remain valid.
Time, temperature, and moisture content should be monitored continuously to ensure effectiveness
of treatment.
Monitor to ensure that pH 12 (at 25°C) is maintained for more than 72 hours for all sewage sludge.
Once reduced, enteric virus or viable helminth ova does not regrow. To establish a process,
determine with each monitoring episode until the process is shown to consistently achieve this
status. Then continuously monitor process to ensure it is operated as it was during the
demonstration.
Once reduced, enteric virus or viable helminth ova does not regrow. Monitor representative sample
of sewage sludge:
(a) at the time of use or disposal, or
(b) when prepared for sale or give-away in a bag or other container for land application, or
(c) when prepared to meet EQ requirements.
Monitor at sufficient frequency to show compliance with time and temperature or irradiation
requirements.
Monitor at sufficient frequency to show compliance with PFRP or equivalent process requirements.
Pathogens Class B
Class B PRA 1:
Fecal Coliform
Class B PRA 2:
Class B PRA 3:
Measure the geometric mean of 7 samples at the time the sewage sludge is used or disposed.
Monitor at sufficient frequency to show that the PSRP requirements are met.
Monitor at sufficient frequency to show that the equivalent PSRP requirements are met.
Vector Attraction Reduction
Vector Attraction Reduction (VAR) 1:
38% Volatile Solids
Reduction (VSR)
VAR 2:
for Anaerobic Digestion:
Lab Test
VAR 3:
for Aerobic Digestion:
Lab Test
VAR 4:
SOUR Test for
Aerobic Processes
Once achieved, no further attractiveness to vectors. Follow Part 503 frequency of monitoring
requirements.
Once achieved, no further attractiveness to vectors. Follow Part 503 frequency of monitoring
requirements.
VAR 5:
Aerobic >40°C
Monitor at sufficient frequency to show that sewage sludge is achieving the necessary temperatures
over time.
VAR 6:a
Adding Alkali
Determine pH over time. Data are valid as long as the pH does not drop such that putrefaction
begins prior to land application.
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Table 13-1. (continued)
VAR 7:a
Moisture Reduction
No Unstabilized
Primary Solids
VAR 8:a
Moisture Reduction
Primary Unstabilized
Solids
VAR 9:b
Injection into Soil
VAR 10b:
Incorporation into Soil
VAR 11b:
Covered with Soil
(Surface Disposal Only)
VAR 12b:
Domestic Septage
pH Adjustment
To be achieved only by the removal of water. VAR 7 has been achieved as long as the moisture
level remains below 30%.
To be achieved only by the removal of water. VAR 8 has been achieved as long as the moisture
level remains below 10%.
No significant amount of sewage sludge remains on soil surface within 1 hour after injection.
Sewage sludge must be incorporated into soil within 6 hours after being placed on the soil surface.
Surface disposed sewage sludge must be covered daily.
Preparer must ensure that pH is 12 for more than 30 minutes for every container of domestic
septage treated with alkali.
1 EPA is proposing that requirements for options 6, 7, and 8 be met at the time of use or disposal.
' Conditions for options 9-12 must be maintained at all times if one of these options is chosen to meet vector attraction reduction requirements.
13.2.2 Frequency of Monitoring
The Part 503 regulation establishes minimum fre-
quency of monitoring requirements for sewage sludge
that is land applied based on the amount of sewage
sludge applied at a site in a year, as discussed in Chap-
ter 3 and shown in Table 3-15. The permitting authority
may require increased frequency of monitoring if certain
conditions exist, such as if no previous sampling data
are available on the sewage sludge to be land applied
or if pollutant concentrations or pathogen densities vary
Table 13-2. Sampling Points for Sewage Sludge
Sewage Sludge Type
significantly between measurements. The permitting
authority also may reduce the frequency of monitoring to
a minimum of once annually if certain conditions exist (i.e.,
after two years, the variability of pollutant concentrations
or pathogen density is low and compliance is demonstrated).
Permitting requirements regarding frequency of monitor-
ing may differ depending on whether sewage sludge is
continuously land applied or is stored prior to land ap-
plication, to ensure collection of a representative sample
of the sewage sludge that is actually land applied.
Sampling Point
Anaerobically Digested
Aerobically Digested
Thickened
Heat Treated
Dewatered, Dried, Composted
Dewatered by Belt Filter Press,
Centrifuge, Vacuum Filter Press
Dewatered by Sewage Sludge
Press, (plate and frame)
Dewatered by Drying Beds
Compost Piles
Collect sample from taps on the discharge side of positive displacement pumps.
Collect sample from taps on discharge lines from pumps. If batch digestion is used, collect sample
directly from the digester. Cautions:
1. If biosolids are aerated during sampling, air entrains in the sample. Volatile organic compounds may
be purged with escaping air.
2. When aeration is shut off, solids may settle rapidly in well-digested sewage sludge.
Collect sample from taps on the discharge side of positive displacement pumps.
Collect sample from taps on the discharge side of positive displacement pumps after decanting. Be
careful when sampling heat-treated sewage sludge because of:
1. High tendency for solids separation.
2. High temperature of sample (temperature < 60°C as sampled) can cause problems with certain
sample containers due to cooling and subsequent contraction of entrained gases.
Collect sample from material collection conveyors and bulk containers. Collect sample from many
locations within the sewage sludge mass and at various depths.
Collect sample from sewage sludge discharge chute.
Collect sample from the storage bin; select four points within the storage bin, collect equal amount of
sample from each point and combine.
Divide bed into quarters, grab equal amounts of sample from the center of each quarter and combine to
form a composite sample of the total bed. Each composite sample should include the entire depth of
the sewage sludge material (down to the sand).
Collect sample directly from front-end loader while sewage sludge is being transported or stockpiled
within a few days of use.
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13.2.3 Sample Collection
Liquid sewage sludge from pipelines should be sampled
as far downstream as possible to take advantage of
maximum mixing, thus reflecting the most representative
sample of sewage sludge to be land applied. If liquid
sewage sludge must be sampled from a lagoon, floating,
suspended, and sediment layers should be included in
the sample.
For dewatered sewage sludge (10% to 40% solids),
sampling is best done when the sewage sludge is being
moved to maximize representativeness. A convenient
way to collect samples might be to sample haul truck
loads at a frequency that obtains the minimum number
of samples needed, as required by the frequency of
monitoring specified in the Part 503 regulation. This
frequency can be determined by dividing the annual
tonnage or cubic yards of sewage sludge by the calcu-
lated number of samples to determine how often haul
trucks or spreaders should be sampled. For example, if
250 cubic yards of sewage sludge are hauled to the site
annually in haul trucks with a 25-cubic-yard capacity,
and if 10 samples are required, then one composite grab
sample from every truck load might suffice, or several
samples from each truckload might be needed to obtain
a representative sample. If half that amount was hauled
in a year, then two composite grab samples representing
the front and back half of each truck would be needed.
If the amount of sewage sludge requires more truck
loads than samples, then samples would be taken of the
required percentage of loads to obtain the requisite
number of samples.
Other EPA documents (U.S. EPA, 1989, 1993, 1994)
provide more detailed guidance on specific procedures
for collecting sewage sludge samples.
Sample collection and handling procedures should be
clearly defined and consistently followed to minimize
sample errors attributable to the sampling process. This
can be accomplished with a written sampling protocol
that includes:
• Specification of personnel responsible for collecting
samples, and training requirements to ensure that the
sampling protocol is correctly followed.
• Specification of safety precautions to prevent expo-
sure of sampling personnel to pathogenic organisms,
such as use of gloves when handling or sampling
untreated or treated sewage sludge and cleaning of
sampling equipment, containers, protective clothing,
and hands before delivering samples to others.
• Identification of the appropriate type of sampling de-
vice. For liquid sewage sludge, certain types of plas-
tic (e.g., polyethylene) or glass (e.g., non-etched
Pyrex) may be appropriate, depending on the type of
sample (e.g., metals or pathogens); coliwasas can be
used for sampling liquid sewage sludge from la-
goons. For dewatered sewage sludge, soil sampling
devices, such as scoops, trier samplers, augers, or
probes can be used. If steel devices are used, stain-
less steel materials are best; chrome-plated samplers
should be avoided.
• Description of sample mixing and subsampling pro-
cedures when grab samples of sludge are compo-
sited and only part of the composite sample is used
for analysis. This usually requires use of a mixing
bowl or bucket (stainless steel or Teflon) or a dispos-
able plastic sheet on which samples can be mixed
and from which a smaller sample can be taken.
• Specification of the size and material of sample con-
tainers. Table 13-3 identifies suitable containers and
minimum volume requirements for sludge sampling.
Sample containers can often be obtained from the
person or laboratory responsible for doing the sample
analysis.
• Specification of sample preservation procedures and
sample holding times. Table 13-3 identifies these re-
quirements for sludge samples. The appropriate
regulatory agency, in coordination with the testing
laboratory, should be contacted to identify any re-
quired sample preservation procedures and holding
times for all constituents being monitored.
• Specification of sample equipment cleaning proce-
dures to ensure that cross-contamination of samples
does not occur. ASTM D5088 (Standard Practice for
Decontamination of Field Equipment Used at Nonra-
dioactive Waste Sites) provides guidance on these
procedures.
• Specification of types and frequency of quality assur-
ance/quality control (QA/QC) samples. Again, the ap-
propriate regulatory agency should be contacted to
determine which types of QA/QC samples may be
required for the site.
• Description of sample chain-of-custody procedures to
ensure that the integrity of samples is maintained
during transport and analysis of samples.
13.2.4 Analytical Methods
Table 13-4 identifies analytical methods for pathogens,
inorganic pollutants, and other sewage sludge parame-
ters that are required by the Part 503 regulation. Specific
methods for sewage sludge sample preparation and
analysis for metals of interest are contained in Test
Methods for Evaluating Solid Waste (U.S. EPA, 1986).
13.3 Soil Monitoring and Sampling
Soil sampling and analysis for constituents affecting
plant growth (see Chapter 6) may be needed to ensure
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Table 13-3. Sewage Sludge Sample Containers, Preservation, and Storage
Parameter
Wide-Mouthed
Container
Preservative3
Minimum
Maximum Storage Time3 Volumeb
Metals
Solid and semi-solid P, G
samples
Cool, 4°C
24 hours
300ml
Mercury (liquid)
All other liquid metals
R G
P, G
HN03topH<2 28 days
HNO3 to pH < 2 6 months
500ml
1,000 ml
Pathogen Density and Vector Attraction Reduction
Pathogens
G, P, B, SS
1 . Cool in ice and water to <10°C 6 hours
if analysis delayed >1 hr, or (bacteria)
1 -4 liters0
Vector attraction
reduction
2. Cool promptly to < 4°C, or
3. Freeze and store samples to
be analyzed for viruses at 0°Cd
Variesb
24 hours (bacteria and viruses)
1 month (helminth ova)
2 weeks
Varies13
1 -4 liters0
a Preservatives should be added to sampling containers prior to actual sampling episodes. Storage times commence upon addition of sample
to sampling container. Shipping of preserved samples to the laboratory may be, but is generally not, regulated under Department of
Transportation hazardous materials regulations.
b Varies with analytical method. Consult 40 CFR Part 503. For dry sewage sludge, convert to dry weight (DW). DW = wet -=- percent solids.
c Reduced at the laboratory to approx. 300 ml samples.
d Do not freeze bacterial or helminth ova samples.
P = Plastic (polyethylene, polypropylene, Teflon)
G = Glass (non-etched Pyrex)
B = Presterilized bags (for dewatered or free-flowing biosolids)
SS = Stainless steel (not steel- or zinc-coated)
Table 13-4. Analytical Methods for Sewage Sludge Sampling3
Sample Type Method
Enteric Viruses
Fecal Coliform
Helminth Ova
Inorganic Pollutants
Salmonella sp. Bacteria
Specific Oxygen Uptake Rate
Total, Fixed, and Volatile Solids
Percent Volatile Solids Reduction Calculation
ASTM Designation: D 4994-89, Standard Practice for Recovery of Viruses from
Wastewater Sludges, Annual Book of ASTM Standards: Section 11. Water and
Environmental Technology, ASTM, Philadelphia, PA, 1992.
Part 9221 E or Part 922 D, Standard Methods for the Examination of Water and
Wastewater, 18th edition, American Public Health Association, Washington, DC, 1992.
Yanko, W.A., Occurrence of Pathogens in Distribution and Marketing Municipal Sludges,
EPA/600/1-87/014, 1987. PB 88-154273/AS, National Technical Information Service,
Springfield, VA; (800) 553-6847.
Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, EPA Publication
SW-846, 3rd edition (1986) with Revision I. 2nd edition. PB 87-120291, National
Technical Information Service, Springfield, VA. 3rd edition Doc. No. 955-001-00000-1,
Superintendent of Documents, Government Printing Office, Washington, DC.
Part 9260 D, Standard Methods for Examination of Water and Wastewater, 18th edition,
American Public Health Association, Washington, DC, 1992; or, Kenner, B.A. and H.P.
Clark, Detection and Enumeration of Salmonella and Pseudomonas aeruginosa, J.
Water Pollution Control Federation, 46(9):2163-2171, 1974.
Part 2710 B, Standard Methods for the Examination of Water and Wastewater, 18th
edition, American Public Health Association, Washington, DC, 1992.
Part 2540 G, Standard Methods for the Examination of Water and Wastewater, 18th
edition, American Public Health Association, Washington, DC, 1992.
Environmental Regulations and Technology—Control of Pathogens and Vectors in
Sewage Sludge, EPA/625/R-92/013, U.S. Environmental Protection Agency, Cincinnati,
OH, 1992; (614) 292-6717.
'All of these analytical methods are required by the Part 503 rule, except the Percent Volatile Solids Reduction Calculation, which is provided
as guidance in the Part 503 rule.
151
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vigorous crop production. Soil monitoring is not a Part
503 requirement. As discussed in Chapter 6, soil sam-
pling at sewage sludge land application sites is per-
formed primarily to assist in determining soil chemical
parameters (N, P, and K) for calculation of sewage
sludge and supplemental fertilizer application rates to
supply plant nutrient requirements. Additional site-
specific analyses may be needed to monitor the status
of some land application systems. For example, soils
may need to be analyzed for soluble salts and/or boron
in semiarid regions where irrigation is planned. Table
13-5 summarizes potential surface and subsurface soil
parameters that may be useful to monitor prior to or after
sewage sludge land application. Advice should be ob-
tained from the local University Cooperative Extension
Service, County Agricultural Agents, and/or others with
expertise in sampling and analysis of soils in the sewage
sludge land application site area.
Table 13-5. Potential Soil Surface Layer and Subsurface
Parameters of Interest
Monitoring Prior to Sewage Sludge Application
Surface Layer
Particle size distribution
PH
Electrical conductivity
Cation exchange capacity (CEC)
Lime requirement (acid soils)
Plant available P and K
Soil N parameters
N03-N
NH4-N
Organic matter
Organic-N
C:N ratio
Soil microbial biomass C and N
N mineralization potential
Subsurface Layers
Particle size distribution
PH
Electrical conductivity
Cation exchange capacity (CEC)
Monitoring After Sewage Sludge Application
PH
Electrical conductivity
Lime requirement (acid soils)
Plant available P and K
Soil N parameters
Organic matter
Organic-N
PH
Electrical conductivity
13.3.1 Sampling Location and Frequency
Initially, soil samples can be collected from each field
where sewage sludge will be land applied. Generally, if
a given field exceeds 10 ha (25 ac), individual soil
samples should be collected from each soil series within
the field. The number and location of samples necessary
to adequately characterize soils prior to sewage sludge
land application is primarily a function of the spatial
variability of the soils at the site. If the soil types occur
in simple patterns, a composite sample of each major
type can provide an accurate picture of the soil charac-
teristics. The site soil map described in Chapter 6 will
identify major soil types that should be sampled.
Soil pH measurements can be done in the field at relatively
low cost. Thus, measuring the pH of soil samples taken on
a grid pattern (e.g., 30 m [100 ft] sections), can serve as a
useful indicator of the degree of spatial variability within soil
map units. If pH is variable, drawing contours of equal pH
will identify subareas in a soil type where separate com-
posite samples should be collected. Such a map also is
useful when the pH of soil needs to be adjusted.
Once initial sampling and analysis of soil samples is
completed, the frequency of subsequent sampling will
depend on land use and any state regulatory soil moni-
toring requirements. For agricultural crops, pH, P, and K
soil tests are typically done every two years. Monitoring
of these parameters typically is not required for forest
land application sites. As discussed in Section 13.6.3,
monitoring requirements at reclamation sites will typically
be more extensive than at agricultural and forest sites.
If sewage sludge is applied at agronomic rates to supply
plant N requirements (as is required by Part 503), peri-
odic monitoring of soil-available N may be useful be-
cause of the difficulty in accurately predicting N
mineralization rates of sewage sludge. Annual monitor-
ing of soil N is appropriate for irrigated crops, as well as
certain non-irrigated crops such as corn. Annual moni-
toring is less critical at forest sites because crops are
not removed each year, but may be performed initially
to gain an understanding of nitrogen dynamics at the
site. Section 13.3.4 further discusses test methods for
estimating N availability.
13.3.2 Number of Samples
In some states, the state regulatory agency stipulates
the minimum number of soil borings which must be
analyzed. New Jersey, for example, historically has
based the minimum number of soil borings required
based on the proposed sewage sludge land application
site area, ranging from a minimum of 3 borings on small
sites (up to 4 ha [10 ac]) to 24 borings on large sites
(over 80 ha [200 ac]. Samples taken from similar soil
horizons are usually composited for several borings lo-
cated near each other in homogeneous soil. The com-
posited samples are subsequently analyzed.
13.3.3 Sample Collection
The proper selection of tools for collection of soil samples
depends in part on the texture and consistency of the soil,
the presence or absence of rock fragments, the depth to
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be sampled, and the degree of allowable soil surface
disturbance. Soil samples are most accurately taken
from a freshly dug pit. Where field plots are to be sam-
pled periodically, however, preferable sampling tools are
those which disturb the plot the least. Cutaway soil
sampling tubes, closed cylinder augers, and tiling
spades (sharp-shooters) may be used depending on the
size of the plot and allowable disturbance. The cutaway
soil sampling tube creates the least disturbance, and
works well in the plow layer and the upper subsoil of moist,
stone-free, friable soils. Each sample collected should
represent the cross section of the soil layer being sampled.
In sampling subsurface soils, care must be taken to
remove loose particles of sewage sludge residue on the
soil surface around the hole prior to and during sam-
pling. In addition, any surface soil/sludge residue at-
tached to the top and side of the core samples from
lower depths should be removed by slicing with a knife.
Where cores extend below the depth of the seasonal
high water table, it is recommended that the holes be
sealed by filling with bentonite pellets and tap water. A
map showing sample points should be made.
The depth to which the soil profile is sampled and the
extent to which each horizon is vertically subdivided
depend largely on the parameters to be analyzed, the
vertical variations in soil character, and the objectives
of the soil sampling program. For initial charac-
terization, samples are typically taken from each dis-
tinct soil horizon down to a depth of 120 to 150 cm (4
to 5 ft). For example, samples may be taken from four
soil depths (horizons) as follows: 0 to 15 cm (0 to 6 in),
15 to 45 cm (6 to 18 in), 45 to 75 cm (18 to 30 in), and
75 to 120 cm (30 to 42 in). Usually, at a minimum,
samples are taken from the upper soil layer (e.g., 0
to 15cm [Oto6 in]) and a deeper soil horizon (e.g., 45
to 75 cm [18 to 30 in]).
Subsequent samples for pH, P, and K monitoring are
usually confined to the surface layer at 0-15 or 0-30 cm,
depending on the thickness of the soil A horizon. Rec-
ommended sampling depths for developing NOs profiles
generally vary from 0.6 to 1.2 m, depending on the crop
and state. These variations are based on depths known
to represent the best correlation between soil-NO3 and
crop yield in particular areas and with particular crops.
Advice should be obtained from the local University
Cooperative Extension Service, County Agricultural
Agents, and/or others with expertise in sampling and
analysis of soils in the locality of the sewage sludge land
application site concerning recommended sampling
depths for NO3 profiles. Depths up to 60 cm can usually
be collected by hand without much difficulty. Collection
of samples exceeding 60 cm usually requires use of
power-driven soil sampling equipment.
Estimation of N immobilization (see Chapter 8) associ-
ated with initial sewage sludge application at forest sites
involves sampling of forest litter to measure the amount
of C and N. Representative samples of twigs, leaves,
and partially decomposed litter on the forest floor can be
collected and weighed to determine the total amount of
litter in kg/ha. It may also be desirable to quantify the
macroorganic fraction of the soil surface (the sand-sized
fraction of soil organic matter). Gregorich and Ellert
(1993) discuss methods for measuring this fraction.
Soil samples should be air-dried (at temperatures less
than 40°C), ground, and passed through a 2-mm sieve
as soon as possible after collection. Chemical analyses
are generally performed on air-dried samples, which do
not require special preservation for most parameters.
Samples collected for nitrate, ammonia, and pathogen
analyses, however, should be refrigerated under moist
field conditions and analyzed as soon as possible.
13.3.4 Analytical Methods
Major reference sources for standard methods for physi-
cal and chemical analysis of soil samples include: Carter
(1993), Council on Soil Testing and Analysis (1992),
Klute (1986), Page et al. (1982), Soil Conservation Serv-
ice (1984), and Westerman (1990).
13.3.4.1 Nitrogen
Keeney (1982) provides a summary of soil analysis
methods used in different states to develop N fertilizer
recommendations. The most commonly used methods
are: (1) NO3 profiles, and (2) measurement of soil or-
ganic matter content in the surface soil. NO3 profiles are
most commonly used in western states where crops are
grown under irrigation, but Sander et al. (1994) note that
the pre-sidedress nitrate test (PSNT) has been demon-
strated to be a useful test for corn crops in more humid
climates. Measurement of organic matter content is
used by a number of states in both the eastern and
western United States to directly or indirectly estimate
mineralizable N. Missouri has refined the use of organic
matter by basing N mineralization rate estimates on soil
texture (Keeney, 1982).
Measurements of the mineralization potential of soils
and of soils amended with sewage sludge usually are
accomplished using laboratory soil column biological
incubation methods. Keeney (1982) and Campbell et al.
(1993) describe these methods. Most of the references
identified at the beginning of this section cover the wide
variety of methods that are available for determination
of organic and inorganic forms of N in soils.
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13.3.4.2 Plant-Available Phosphorus and
Potassium
The amount of plant-available P is determined by ana-
lyzing the amount of P removed from soil by a particular
extractant. The extractant used varies in different re-
gions of the United States, but typically is a dilute acid
or a bicarbonate solution. Essentially, all P taken up by
crops is present in insoluble forms in soils rather than
being in the soil solution. In all states, it has been
determined that there is a relationship between the
amount of extractable P in a soil and the amount of P
fertilizer needed for various yields of different crops.
Such information may be obtained from extension serv-
ices or universities.
As with P, an extractant is used to determine the plant-
available K in a soil. Potassium available for plant up-
take is present in the soil solution, and also is retained
as an exchangeable cation on the cation exchange
complex of the soil. The amount of plant-available K is
then used to determine the K fertilizer rate for the crop
grown. Most sewage sludge usually is deficient in K,
relative to crop needs.
13.4 Surface-Water and Ground-Water
Monitoring
The risk-based pollutant limits and the management
practices for land application specified in the federal
Part 503 rule are designed to be sufficiently protective
of surface water and ground water so that onsite water
quality monitoring usually is not required at land appli-
cation sites. Some states may require surface or
ground-water monitoring for special conditions at a land
application site, as discussed below.
13.4.1 Surface- Water Monitoring
Properly designed sewage sludge land application sites are
generally located, constructed, and operated to minimize
the chance of surface-water runoff containing sewage
sludge constituents. Surface-water monitoring rarely is
required when sewage sludge is applied at agronomic
rates. In some cases, a state agency may require moni-
toring for special situations. In these cases, the state
usually will specify monitoring locations and procedures.
13.4.2 Ground-Water Monitoring
Sewage sludge land application at agronomic rates should
pose no greater threat of NO§ contamination of ground
water than does the use of conventional N fertilizers.
Special conditions at a land application site may result in
ground-water monitoring requirements by the state. In
such cases, monitoring locations and procedures typically
will be specified by the appropriate state agency.
13.5 Vegetation Monitoring
The federal Part 503 pollutant limits and management
practices for land application specified in the Part 503
rule are designed to be sufficiently protective of vegeta-
tion regarding uptake of heavy metals so that onsite
monitoring of vegetation is not required. Vegetation
monitoring may be conducted for public relations pur-
poses, when it is desirable to assure private crop or tree
farm owners that their crops are not being adversely
affected by the use of sewage sludge. Table 13-6 sum-
marizes sampling procedures for field crops and pas-
tures.
13.6 Monitoring and Sampling at
Reclamation Sites
13.6.1 General
If a land application program at a reclamation site complies
with applicable requirements, the sewage sludge will pose
little potential for adverse effects on the environment, and
no monitoring is necessary beyond the Part 503 frequency
of monitoring requirements (see Chapter 3). Some states
require monitoring at a reclamation site after the sewage
sludge has been land applied. Special monitoring and
sampling procedures may be needed for such monitoring
because of more complex site geochemistry compared
to undisturbed soils.
13.6.2 Disturbed Soil Sampling Procedures
Standard soil sampling procedures employed on agri-
cultural fields can often be used for reclamation sites
that have had topsoil replaced. For some unreclaimed
sites, more intensive sampling may be necessary to
characterize site conditions. In heterogenous materials,
such as mine spoils, an adequate determination of con-
ditions may require sampling on a grid pattern of ap-
proximately 30 m (100 ft) over the entire site.
Although the disturbed surface materials often are not
soil in the generic sense, soil tests on disturbed lands
have proven useful. Soil tests on drastically disturbed
sites, however, do have some limitations that should be
taken into consideration during site evaluation. Guide-
lines vary widely on the number of samples to betaken.
Recommendations for sampling heterogeneous strip
mine spoils in the eastern U.S. range from 4 to 25
individual samples per ha (1.5 to 10 per ac). It has also
been suggested that one composite sample made up
of a minimum of 10 subsamples for each 4 ha (10 ac)
area may be adequate (Barnhisel, 1975). Many dis-
turbed lands are not heterogeneous, however, and the
range and distribution of characteristics of the surface
material often is more important than the average com-
position. In general, it is recommended that material
that is visibly different in color or composition should
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Table 13-6. Suggested Procedures for Sampling Diagnostic Tissue of Crops (Walsh and Beaton, 1973)
Crop Stage of Growth3 Plant Part Sampled
Number
Plants/Sample
Corn
Soybeans and other beans
Small grains
Seedling
Prior to tasseling
From tasseling to silking
Seedling
Prior to or during early flowering
Seedling
Prior to heading
Hay, pasture or forage grasses Prior to seed emergence
Alfalfa, clover and other legumes Prior to or at 1/10 bloom
Sorghum-milo
Cotton
Potato
Head crops (e.g., cabbage)
Tomato
Beans
Root crops
Celery
Leaf crops
Peas
Melons
Prior to or at heading
Prior to or at 1st bloom, or at 1st
square
Prior to or during early bloom
Prior to heading
Prior to or during early bloom stage
Seedling
Prior to or during initial flowering
Prior to root or bulb enlargement
Mid-growth (12-15 in. tall)
Mid-growth (12-15 in. tall)
Prior to or during initial flowering
Prior to fruit set
All the aboveground portion. 20-30
Entire leaf fully developed below whorl. 15-25
Entire leaf at the ear node (or immediately 15-25
above or below).
All the aboveground portion. 20-30
Two or three fully developed leaves at top of 20-30
plant.
All the aboveground portion. 50-100
The 4 uppermost leaves. 50-100
The 4 uppermost leaf blades. 40-50
Mature leaf blades taken about 1/3 of the way 40-50
down the plant.
Second leaf from top of plant. 15-25
Youngest fully mature leaves on main stem. 30-40
3rd to 6th leaf from growing tip. 20-30
1st mature leaves from center of whorl. 10-20
3rd or 4th leaf from growth tip. 10-20
All the aboveground portion. 20-30
2 or 3 fully developed leaves at the top of plant. 20-30
Center mature leaves. 20-30
Petiole of youngest mature leaf. 15-30
Youngest mature leaf. 35-55
Leaves from 3rd node down from top of plant. 30-60
Mature leaves at base of plant on main stem. 20-30
1 Seedling stage signifies plants less than 12 in. tall.
be sampled as separate units (areas) if large enough
to be treated separately in the reclamation program.
13.6.3 Suggested Monitoring Program
13.6.3.1 Background Sampling (Prior to Sewage
Sludge Application)
Composite sewage sludge samples can be collected
and analyzed to provide data for use in designing load-
ing rates. Composite soil samples can be collected from
the site to determine pH, liming requirements, CEC,
available nutrients, and trace metals prior to sewage
sludge addition.
13.6.3.2 Sampling During Sewage Sludge
Application
When the sewage sludge is delivered, grab samples can
be taken and analyzed for moisture content if there is
variation in the moisture content of the sewage sludge.
Composite sewage sludge samples also should be col-
lected to assist in documenting the actual amounts of
nutrients applied to the site (and trace metal amounts
applied, if Part 503 CPLR pollutant limits are being met,
see Chapter 3).
13.6.3.3 Post-Sewage Sludge Application
Monitoring
Monitoring of the sewage sludge application site after
the sewage sludge has been applied can vary from none
to extensive, depending on state and local regulations
and site-specific conditions. Generally, it is desirable to
analyze the soil after 1 year for soil pH changes. In
addition, periodic surface and ground water analysis
may be useful to document any long-term changes in
water quality.
Some states have very specific requirements for moni-
toring, and the designer should consult the appropriate
regulatory agency. Monitoring requirements by the State
of Pennsylvania (Pennsylvania Department of Environ-
mental Resources, 1988) provide an example:
155
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The Pennsylvania Department of Environmental
Resources (DER) requires a ground-water
monitoring system on mine land amended with
sewage sludge. The system must consist of the
following, at a minimum: (1) at least one
monitoring well at a point hydraulically
upgradient in the direction of increasing static
head from the area in which sewage sludge has
been applied; (2) at least three monitoring wells
at points hydraulically downgradient in the
direction of decreasing static head from the area
treated with sewage sludge; and (3) in addition to
the three wells, the DER may allow one or more
springs for monitoring points if the springs are
downgradient from the treated sewage sludge
area. Surface water monitoring points may also
be required by the DER if appropriate for the
specific site.
Ground-water samples must be collected and
analyzed at required frequencies for various
parameters, including Kjeldahl nitrogen,
ammonia-nitrogen, nitrate-nitrogen; certain metals,
organics, and other water quality indicators; and
ground-water elevation in monitoring wells. The
DER may also require soil-pore water monitoring
using lysimeters located in the unsaturated zone
within 36 inches of the soil surface. Soil sampling
for certain metals, pH, and phosphorus using
DER procedures is required for mine reclamation
sites that may be used for agriculture. For crops
grown for animal consumption, the DER may
require a crop analysis, usually for certain
specified metals.
13.7 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
Barnhisel, R. 1975. Sampling surface-mined coal spoils. Department
of Agronomy Report AGR-41, University of Kentucky, Lexington, KY.
Campbell, C., B. Ellert, and Y. Jame. 1993. Nitrogen mineralization
potential in soils. In: Carter, M.R., ed. Soil sampling and methods
of analysis. Lewis Publishers, Boca Raton, FL, pp. 341-349.
Carter, M., ed. 1993. Soil sampling and methods of analysis. Lewis
Publishers, Boca Raton, FL.
Council on Soil Testing and Analysis. 1992. Reference methods for
soil analysis. Georgia University Station, Athens, GA.
Gregorich, E. and B. Ellert. 1993. Light fraction and macroorganic
matter in mineral soils. In: Carter, M., ed. Soil sampling and meth-
ods of analysis. Lewis Publishers, Boca Raton, FL, pp. 397-407.
Keeney, D. 1982. Nitrogen-availability indices. In: Page, A.L., ed.
Methods of soil analysis, part 2, 2nd ed. American Society of
Agronomy, Madison, Wl, pp. 711-733.
Klute, A., ed. 1986. Methods of soil analysis, part 1: Physical and
mineralogical methods, 2nd edition. Agronomy Monograph No. 9,
American Society of Agronomy, Madison, Wl.
Page, A., R. Miller, D. Keeney, eds. 1982. Methods of soils analysis,
part 2—Chemical and microbiological properties, 2nd edition. ASA
Monograph 9, American Society of Agronomy, Madison, Wl.
Pennsylvania Department of Environmental Resources. 1988. Land
application of sewage sludge. In: Pennsylvania Code, Title 25,
Chapter 275.
Sander, D., D. Walthers, and K. Frank. 1994. Nitrogen testing for
optimum management. Journal of Soil and Water Conservation
49(2):46-52.
Soil Conservation Service (SCS). 1984. Procedures for collecting soil
samples and methods of analysis for soil survey. Soil Survey
Investigations Report No. 1, U.S. Government Printing Office.
U.S. EPA. 1994. A plain English guide to the EPA Part 503 biosolids
rule. EPA/832/R-93/003. Washington, DC.
U.S. EPA. 1993. Preparing sewage sludge for land application or
surface disposal: A guide for preparers of sewage sludge on the
monitoring, record keeping, and reporting requirements of the fed-
eral standards for the use or disposal of sewage sludge, 40 CFR
Part 503. EPA/831/B-93/002a. Washington, DC.
U.S. EPA. 1992. Environmental regulations and technology: Control of
pathogens and vector attraction in sewage sludge. EPA/625/R-
92/013. Washington, DC.
U.S. EPA. 1989. POTW sludge sampling and analysis guidance docu-
ment. NTIS PB93227957. Washington, DC.
U.S. EPA. 1986. Test methods for evaluating solid waste, 3rd ed.
EPA/530/SW-846 (NTIS PB88239223). Current edition and up-
dates available on a subscription basis from U.S. Government
Printing Office, Stock #955-001-00000-1.
Walsh, L. and J. Beaton, eds. 1973. Soil testing and plant analysis.
Soil Science Society of America, Madison, Wl.
Westerman, R., ed. 1990. Soil testing and plant analysis, 3rd edition.
Soil Science Society of America, Madison, Wl.
156
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Chapter 14
General Design Considerations
14.1 Introduction
This chapter provides guidance for designing the com-
ponents of a land application system, including:
• Sewage sludge transport systems
• Sewage sludge storage
• Land application methods
• Site preparation
• Supporting facilities
The designer should take into consideration each com-
ponent's impact on overall system efficiency, reliability,
and cost when selecting and designing each of these
individual components of a land application system. For
example, the most economical sewage sludge transpor-
tation method may not result in the lowest overall system
cost because of associated high costs at the treatment
plant and/or land application site.
14.2 Transportation of Sewage Sludge
14.2.1 Transport Modes
Efficient transport of sewage sludge should be a key
design consideration. Potential modes of sewage sludge
transportation include truck, pipeline, railroad, or various
combinations of these three modes (Figure 14-1).
The method of transportation chosen and its costs de-
pend on a number of factors, including:
• Characteristics and quantity of the sewage sludge to
be transported.
• Distance from the treatment works to the application
site(s).
• Availability and proximity of the transportation mode(s)
to both origin and destination (e.g., roads, proximity
of railroad spurs).
• Degree of flexibility required in the transportation
method chosen.
• Estimated useful life of the land application site based
on site characteristics (e.g., topography, vegetative
cover, soil type, area available).
• Environmental and public acceptance factors.
To minimize the danger of spills, liquid sewage sludge
should be transported in closed tank systems. Stabi-
lized, dewatered sewage sludge can be transported in
open vessels, such as dump trucks and railroad gondo-
las if equipped with watertight seals and anti-splash
guards.
14.2.2 Vehicle Transport
14.2.2.1 Vehicle Types Available
Trucks are widely used for transporting both liquid and
dewatered sewage sludge and are generally the most
flexible means of transportation. Terminal points and haul
routes can be readily changed with minimal cost. Trucks
can be used for hauling sewage sludge eitherto the final
application site(s) or to an intermediate transfer point
such as railroad yards. Access to sewage sludge within
a treatment plant is usually adequate for truck loading.
Many truck configurations are available, ranging from
standard tank and dump bodies to specialized equipment
for hauling and spreading sewage sludge. Depending on
the type of sewage sludge to be hauled, different types
of vehicles can be used, as described below.
Liquid Sewage Sludge
The following types of vehicles can be used to haul liquid
sewage sludge (usually less than 10 percent solids, dry
weight):
• Farm tractor and tank wagon, such as those used for
livestock manure. Normally used only for short hauls
and by small rural communities.
• Tank truck, available in sizes from 2,000 to 24,000 L
(500 to 6,000 gal).
- Tank truck adapted for field application of sewage
sludge in addition to road hauling.
- Tank truck used for road hauling to the land appli-
cation site(s), with sewage sludge subsequently
transferred to a field application vehicle or an irri-
gation system. Such tank trucks are often termed
"nurse trucks."
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Figure 14-1. Examples of sewage sludge transportation modes to land application sites.
Dewatered or Composted Sewage Sludge
The following types of vehicles can be used to haul
dewatered or composted sewage sludge (usually 20 to
60 percent solids, dry weight):
• Dump truck, available in sizes from 6 to 23 m3 (8 to
30 yd3).
• Hopper (bottom dump) truck, available in sizes from
12 to 19 m3 (15 to 25 yd3).
• Either of the above types of trucks can be used for
hauling the sewage sludge to the land application
site(s) and can also be adapted to spread sewage
sludge.
Figure 14-2 shows photographs of some of the types of
trucks listed above.
14.2.2.2 Vehicle Size and Number Required
To properly assess the size and number of vehicles
needed for transporting sewage sludge from the treat-
ment plant to the application site(s), the following factors
should be considered:
• Quantity of sewage sludge, both present and future.
• Type of sewage sludge—liquid or dewatered/com-
posted.
• Distance from treatment plant to application site(s)
and travel time.
• Type and condition of roads to be traversed, including
maximum axle load limits and bridge loading limits.
• Provisions for vehicle maintenance.
• Scheduling of sewage sludge application. In many
areas, significant seasonal variations exist (due to
weather, cropping patterns, etc.) regarding the quan-
tity of sewage sludge that can be applied. The trans-
port system capacity should be designed to handle
the maximum anticipated sewage sludge application
period, taking into consideration any interim sewage
sludge storage capacity available.
• Percent of time when the transport vehicles will be in
productive use. A study (U.S. EPA, 1977a) of trucks
hauling sewage sludge at 24 small to medium size
Figure 14-2a. A 6,500-gallon liquid sludge tank truck (courtesy
of Brenner Tank Company).
Figure 14-2b. A 3,300-gallon liquid sludge tank truck with
2,000-gallon pup trailer (courtesy of Brenner
Tank Company).
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Figure 14-2c. A 25-cubic-yard dewatered sludge haul truck
(courtesy of Converto Manufacturing Company).
communities showed that trucks hauling liquid sewage
sludge were in productive use an average of 48 percent
of the time (range of 7 to 90 percent) based on an
8-hour day and 5-day week. Average use for trucks
hauling dewatered sewage sludge was reported at 29
percent.
Tables 14-1 and 14-2 provide guidelines for estimating
the number of trucks needed for transporting liquid and
dewatered sewage sludge, respectively. While the ta-
bles provide a means for making preliminary comparisons,
they are only a starting point in the decisionmaking proc-
ess for a specific project. For example, the tables can
be used to quickly compare vehicle needs as a function
of whether liquid sewage sludge at 5 percent solids or
an equivalent quantity of dewatered sewage sludge at
25 percent solids will be transported. Assuming a liquid
sewage sludge quantity of 57 million L/yr (15 Mgal/yr,
which corresponds to 58,000 metric tons/yr or 64,000
Tons/yr) compared with an equivalent quantity of dewa-
tered sewage sludge of 11,470 m3/yr (15,000 yd3/yr,
which corresponds to 12,000 metric tons/yr or 13,000
Tons/yr). Also assume a one-way distance of 32 km (20
mi) from the treatment plant to the application site.
Tables 14-1 and 14-2 indicate that for an 8 hr/day op-
eration, approximately six 9,450 L (2,500 gal) tank trucks
are necessary to transport the liquid sewage sludge, while
only one 11.5 m3 (15 yd3) truck is necessary to transport
the dewatered sewage sludge. The difference in fuel
purchase would be 202,000 L/yr (53,500 gal/yr) for the
liquid sewage sludge versus 50,300 L/yr (13,300 gal/yr)
for the dewatered sewage sludge; driver time required
for the liquid sewage sludge would be 15,500 hr/yr
versus 2,600 hr/yr for the dewatered sewage sludge.
The savings in transportation costs for dewatered sew-
age sludge versus liquid sewage sludge can then be
compared to the cost of dewatering the sewage sludge.
The reader should be aware that the above example is
highly simplified in that it assumes that the sewage
sludge transport operation takes place 360 days a year,
allows an average of only 10 percent for labor hours
beyond actual truck operating hours, provides for only 2
Figure 14-2d. A 12-cubic-yard dewatered sludge spreader vehi-
cle (courtesy of Ag-Chem Equipment Company).
hr/day for truck maintenance time, and gives no consid-
eration to effects of sewage sludge type on operating
costs at the application site(s).
14.2.2.3 Other Truck Hauling Considerations
The haul distance should be minimized to reduce costs,
travel time, and the potential for accidents on route to
the application site(s). Factors such as unfavorable topo-
graphic features, road load limits, and population pat-
terns may influence routing so that the shortest haul
distance may not be the most favorable.
Effective speed and travel time can be estimated from
the haul distance, allowing for differences in speed for
various segments of the route and the anticipated traffic
conditions. Periods of heavy traffic should be avoided
from a safety standpoint, for efficiency of operation, and
for improved public acceptability.
The existing highway conditions must be considered in
the evaluation of truck transport. Physical constraints,
such as weight, height, and speed limits, may limit truck
transport and will influence vehicle and route selection.
Local traffic congestion and traffic controls will influence
routing and also should be considered in determining
the transport operation schedule. Public opinion on the
use of local roadways, particularly residential streets,
may have a significant effect on truck transport opera-
tions and routing.
Fuel availability and costs can have a profound impact
on the operation and economy of sewage sludge hauling
activities. Larger trucks tend to be more fuel efficient
than smaller ones. Also, short haul distances over flat
terrain will have lower fuel requirements than long haul
distances over hills.
Truck drivers and mechanics as well as loading and
unloading personnel will be required for large sewage
sludge hauling operations. Small operations may com-
bine these roles into one or two persons. Manpower
requirements can be determined from the operating
schedule.
159
-------
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-------
Hauling Schedule
The operating schedule for sewage sludge hauling can
be simple or very complex. An example of a simple
hauling operation would be a case where all the sewage
sludge generated each day is hauled to a reclamation
site and discharged into a large capacity sewage sludge
storage facility. In such a simple case, the designer can
easily develop an operating schedule for sewage sludge
hauling based on:
• Quantity of sewage sludge to be hauled.
• Average round-trip driving time required.
• Sewage sludge loading and unloading time required.
• Truck maintenance downtime.
• Estimated truck idle time and maintenance downtime.
• Haul truck capacity.
• Length of working shifts and number of laborers (e.g.,
drivers).
• Safety factor for contingencies (e.g., variations in
sewage sludge quantity generated; impassible roads
due to weather).
In contrast to the simple case described above, the
development of a complex sewage sludge hauling
schedule for an agricultural land application program
may involve many privately owned sites. Such a pro-
gram is complicated by the need to take into account the
following additional factors:
• The variation in distance (driving time) from the treat-
ment works to the privately owned farms accepting
the sewage sludge.
• Existence or absence of sewage sludge storage ca-
pacity provided at the application sites.
• Weather, soil conditions, and cropping patterns that
may significantly limit the number of days and loca-
tions for sewage sludge application at the sites.
An example of the large variations in sewage sludge
hauling schedules for a complex agricultural land appli-
cation program is shown in Table 14-3, which indicates
the projected monthly sewage sludge distribution for the
Madison, Wisconsin, "Metrogro" project. Table 14-3
shows that projected utilization is highest during the
spring, summer, and fall months (e.g., April through
October), whereas sludge is not applied during any of
the winter months (December through March). The de-
signer should provide for the necessary sewage sludge
transport, application, equipment, and labor to handle
the maximum sewage sludge distribution months. This
heavy scheduling, however, then results in underutiliza-
tion of equipment during the low demand distribution
months, as well as the potential problem of shifting
employees to other productive work. Some municipali-
Table 14-3. Projected Monthly Sludge Distribution for
Agricultural Sludge Utilization Program, Madison,
Wisconsin (Taylor, 1994)
Month
January
February
March
April
May
June
July
August
September
October
November
December
% of Annual
0
0
0
10.2
19.7
5.2
5.9
14.1
17.2
18.6
9.1
0
Gal/Month
(x 1000)
0
0
0
2,950
5,700
1,500
1,700
4,100
5,000
5,400
2,650
0
Gal/Day*
0
0
0
147,600
285,000
75,000
85,000
205,000
250,000
270,000
132,000
0
*Based on 20-day/month operation
Metric conversion: 1 gal = 3.78 L
ties have supplemented their basic needs with private
haulers during peak periods to help overcome this problem.
Contract Hauling Considerations
Many municipalities, both large and small, use private
contractors for hauling sewage sludge and sometimes
for application of sewage sludge as well. For example,
a contract operator transports, applies, and incorporates
dewatered sewage sludge from the Atlantic Wastewater
Treatment Plant in Virginia Beach, Virginia, to privately
owned farmland. Incorporation is handled by the con-
tractor because the farmers were not incorporating the
sewage sludge promptly (Jacobs et al., 1993).
The economic feasibility of private contract hauling ver-
sus use of publicly owned vehicles and public employ-
ees should be analyzed for most new projects. If a
private contractor is used, it is essential that a compre-
hensive contract be prepared that includes a total man-
agement plan and avoids municipality liability for
mistakes made by the contractor. At a minimum, the
contract should cover the following responsibilities:
• Liability and insurance for equipment and employees.
• Safety and public health protection procedures and
requirements.
• Estimated sewage sludge quantities and handling
procedures.
• Responsibility and methods for handling citizen com-
plaints and other public relations.
• Procedures for accidents, spills, and violation notifi-
cation and mitigation.
162
-------
• Monitoring procedures, record keeping, and reporting
requirements (see Chapter 13 for monitoring needs
and Chapter 15 for recordkeeping and reporting re-
quired by the Part 503 regulation).
• Responsibility for obtaining and maintaining permits,
licenses, and regulatory agency approvals.
• Standard legal provisions for non-performance relief,
termination, etc.
In some instances, sewage sludge is hauled away from
the treatment works or other facility generating or pre-
paring sewage sludge by the user (e.g., farmer, com-
mercial forest grower). Again, the municipality should
obtain competent legal council to avoid potential liability
due to negligence by the private user/hauler.
Additional Facilities Required for Hauling
Sewage sludge loading facilities at the treatment works
or other sewage sludge facility should be placed in an
accessible location. Depending on the type of sewage
sludge being hauled, hoppers, conveyor belts, or pipe-
lines will be needed to load the trucks. Vehicle storage
and a maintenance/repair shop might be useful at the
plant site. Equipment washdown facilities and parking
should be nearby. Similar facilities for truck unloading
and related activities may be necessary at the sewage
sludge application site(s) and/or the sewage sludge
storage facility.
14.2.3 Pipeline Transport
Generally, only liquid sewage sludge of 8 percent solids
or less can be transported by pipeline (U.S. EPA, 1978).
Sewage sludge with higher solids concentrations, how-
ever, have been pumped; for example, the city of Seat-
tle, Washington has reportedly pumped sewage sludge
containing up to 18 percent solids. Also, pipeline trans-
port is not usually feasible if there are multiple, widely
separated land application sites. Other important factors
regarding pipeline transport include:
• Availability of land for sewage sludge application for
projected long-term periods; if an application site has
a short useful life, pipelines are not usually war-
ranted.
• Sufficient sewage sludge volume to justify the high
capital costs of a pipeline, pump station(s), and ap-
purtenances. Generally, municipal sewage treatment
plants sized below 19 million L/day (5 mgd) do not
generate sufficient sewage sludge volume to justify
pipeline transport unless the distance to the land ap-
plication site is short, e.g., less than 3 km (2 mi).
• Existence of a relatively undeveloped and flat pipe-
line right-of-way alignment between the sewage treat-
ment plant and the land application site. Constructing
a new pipeline through developed residential/com-
mercial areas or through hilly terrain is expensive.
If factors such as those listed above are favorable,
transport of sewage sludge by pipeline often can be less
expensive than truck transport per unit volume of sew-
age sludge.
14.2.3.1 Pipeline Design
The effect of solids concentration on sewage sludge flow
characteristics is of fundamental importance in eco-
nomically designing pipelines. Digested sewage sludge
has been observed to exhibit both newtonian and plastic
flow characteristics. Figure 14-3 shows the influence of
sludge solids concentrations on minimum velocities re-
quired for full turbulent flow through a pipeline. The
figure also indicates the frictional head loss and the
range of velocities for economical transportation. Below
approximately 5 percent solids, sewage sludge flow
exhibits newtonian flow characteristics, whereas at con-
centrations above 5 percent, the flow begins to exhibit
plastic flow characteristics. At a solids concentration
below 5 percent, the economics of sewage sludge trans-
port will resemble water transport costs with respect to
frictional head loss and power requirements. The most
cost-effective pipeline design usually assumes opera-
tion just within the upper limits for newtonian flow (ap-
proximately 5.5 percent solids) (Haug et al., 1977). An
extensive discussion of head loss calculations and
equations for sewage sludge pipelines and pumping can
be found in Chapter 14 of the Process Design Manual
for Sludge Treatment and Disposal (U.S. EPA, 1979).
Various pipeline materials are used fortransporting sew-
age sludge, including steel, cast iron, concrete, fiber-
glass, and PVC. For long-distance, high-pressure
sewage sludge pipelines, steel pipe is most commonly
used. Corrosion can be a severe problem unless prop-
erly considered during design. External corrosion is a
function of the pipe material and corrosion potential of
the soil, and can be controlled by a suitable coating
and/or cathodic protection system. Laboratory tests
simulating several digested sewage sludge lines have
indicated that with proper design, only moderate internal
corrosion rates should be expected in long-distance
pipelines conveying sewage sludge. If most of the grit
and other abrasive materials are removed from the di-
gested sewage sludge, wear due to friction is not a
significant factor in pipeline design (U.S. EPA, 1979).
14.2.3.2 Pipeline Appurtenance Design
Commonly used sewage sludge pipeline appurtenances
are discussed briefly below. More extensive discussion
can be found in Chapter 14 of the Process Design Manual
for Sludge Treatment and Disposal (U.S. EPA, 1979).
163
-------
10.0
111
111
u_
o
o
I-
UJ
111
LL
o
UJ
I
z
o
LEGEND
MINIMUM VELOCITY FULLY
TURBULENT FLOW FOR SOUOS
CONCENTRATION RANGE
INCREASING
10.0
VELOCITY FEET/SECOND
METRIC CONVERSIONS!
ONE FT/S£C. = 0.3043 m/SEC.
Figure 14-3. Hydraulic characteristics of sludge solids (U.S. EPA, 1977b).
Gauges
Pressure gauges are installed on the discharge side of
all pumps. They also may be installed on the suction
side of pumps for purposes of head determination. Pro-
tected, chemical-type gauges are generally used for
sewage sludge pumping.
Sampling Provisions
Generally, 2.5 to 3.8 cm (1 to 1-1/2 in) sampling cocks
with plug valves are provided either on the sewage
sludge pump itself or in the pipe adjacent to the pump.
Cleanouts and Drains
Sewage sludge pipelines should include separate
cleanouts and drains for easy clearance of obstructions.
Blind flanges and cleanouts should be provided at all
changes of direction of 45 degrees or more. Valved
drains should be included at all low points in the pipeline,
and pressure vacuum relief valves should be provided
at all high points in the pipeline. Minimum size at
cleanouts is 10 cm (4 in), with a 15 cm (6 in) size
preferred for access of tools.
Hose Gates
A liberal number of hose gates should be installed in the
piping, and an ample supply of flushing water under high
pressure should be available for clearing stoppages.
Measuring Sewage Sludge Quantities
Pump running time totalizers provide a simple method
of approximating the quantities of sewage sludge
pumped. For more sophisticated measurement, Venturi
meters, flow tubes, or magnetic meters with flushing
provisions can be used. Sewage sludge meters should
have provision for bypassing.
14.2.3.3 Pump Station Design
Pump stations used to pump sewage sludge through
long-distance pipelines should be carefully designed by
experienced engineers. This section is not intended to
be a comprehensive guide to design of such stations,
but rather highlights important design considerations
and provides references for more extensive information.
Important factors for designing long-distance sewage
sludge pumping stations include:
164
-------
• Characteristics of the sewage sludge (e.g., type, sol-
ids content, degree of stabilization, abrasive particle
content, viscosity).
• The choice of variable versus constant speed pumps.
• Quantity of sewage sludge, and type and capacity of
sewage sludge storage ahead of the pumps and at
the pipeline terminus.
• Pressure that the pumps must overcome, including
both pipeline friction loss and static (elevation differ-
ence) head.
• Anticipated pump station life.
• Need for future expansion of capacity (e.g., provision
of space for future pumps, power supply, piping, etc.).
• Ease of operation and maintenance.
• Need for standby reliability (i.e., how long the pump
station can be out of service for maintenance, power
failure, etc., as determined by available storage, al-
ternate means of transport, etc.).
The type of sewage sludge most easily pumped over
long distances has the following characteristics: a solids
content below 6 percent; good stabilization (i.e., rela-
tively low in volatile solids); a low concentration of abra-
sive grit; and the absence of large particles and stringy
material. Sewage sludge possessing other charac-
teristics can be dealt with during design, but will normally
result in increased construction, operation, and/or main-
tenance costs. In Arizona, a high-speed centrifugal
pump is used to force dewatered sewage sludge (20
percent solids) and water into a pipe delivering the solids
to the field. The sewage sludge is then reliquified to a
solids content of 4 percent. The solids content of the
sludge at this Arizona site can be adjusted by regulating
the amount of water injected into the pump. The sewage
sludge is then pumped to the application site through a
system of fixed and movable pipes (Jacobs et al., 1993).
Maximum and minimum flow velocities are an important
consideration in pipeline design. A comparison of vari-
able versus constant speed pumps is important for de-
termining the flow through a pipeline. Variable speed
pumps allow for continuous operation and lower storage
requirements. Although constant speed pumping will
require more storage, it is usually more energy efficient
for peak flow dampening by equalization. For sewage
sludge transport, a flow rate of 1 m/s (3 ft/s) is a satis-
factory value; slower rates can promote solids settling
and decomposition, while higher rates can cause scour-
ing and increase head loss. Since pipelines represent a
significant investment and have long service lives, they
should be sized to permit efficient operation under ex-
isting conditions and also provide adequate capacity for
future growth.
The quantity of sewage sludge to be pumped deter-
mines the capacity of the pumps and the pump station.
Capacity is measured by the maximum sewage sludge
pumping rate required; therefore, it is desirable to pro-
vide as constant an output pumping rate as possible
over long periods each day. Ideally, the pumps will with-
draw the sewage sludge from a large volume storage
facility (e.g., a digester) at a steady rate. If possible,
avoid using small storage tanks that require the pumps
to frequently start and stop. The storage facility supply-
ing the pump with sewage sludge should have a liquid
level higher than the elevation of the pump suction
intake. Sewage sludge pumps work much more effi-
ciently and reliably if they have a positive suction head.
The pressure that sewage sludge pumps must over-
come is the elevation difference between the pump
station and the highest point of the sewage sludge
pipeline to the application site; also, friction loss exists
in the pipe and fittings at the maximum sewage sludge
pumping rate (when maximum pressure occurs). The
elevation difference (static head) is fixed by the topog-
raphy of the pipeline alignment. The head loss due to
friction, however, will vary and can be expected to in-
crease with time due to gradual deterioration of the
pipeline, buildup of internal sewage sludge deposits,
and other factors. The designer, therefore, should pro-
vide a safety factor in calculating total pressure loss due
to friction in the pipe and fittings. An excellent discussion
of sewage sludge pipeline head loss due to friction is
found in Chapter 14 of the Process Design Manual for
Sludge Treatment and Disposal (U.S. EPA, 1979).
Type and Number of Pumps
Various types of pumps are used to pump sewage
sludge, including centrifugal, torque, plunger, piston,
piston/hydraulic diaphragm, ejector, and air lift pumps.
Table 14-4 presents a matrix that provides guidance
regarding the suitability of each type of pump for han-
dling different types of sewage sludge. Centrifugal
pumps are commonly selected for long-distance sew-
age sludge pumping because they are more efficient
(i.e., use less energy) and can develop high discharge
pressures. Centrifugal pumps are generally not used for
heavy, primary sewage sludge, however, because they
cannot handle large or fibrous solids. See Chapter 14 in
the Process Design Manual for Sludge Treatment and
Disposal (U.S. EPA, 1979) for a more detailed descrip-
tion of pump types.
The number of pumps installed in a pump station will
depend largely on the station capacity and the range in
sewage sludge volumes to be pumped. It is customary
to provide a total pumping capacity equal to the maxi-
mum expected inflow with at least one of the pumping
units out of service. In stations handling small flows, two
pumps are usually installed, with each pump capable of
165
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166
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meeting the maximum inflow rate. For larger stations,
the size and number of pumps should be selected so
that the range of inflow can be met without starting and
stopping pumps too frequently (Water Pollution Control
Federation, 1981).
Unless the designer is certain that future pump station
expansion will not be necessary, space, fittings, etc.,
should be provided in the pump station for future addi-
tional pumping capacity.
The design should assume that the pump station will
occasionally be inoperative due to maintenance, power
failure, etc. Sufficient storage capacity should be pro-
vided for sewage sludge, and/or standby power, to han-
dle at least two days of pumping station shutdown.
Emergency tank truck hauling by a private firm is one
alternative that could be arranged in advance.
14.2.3.4 Decisionmaking Factors for Pipeline
Transport
Major factors to consider in an initial evaluation of sew-
age sludge pipeline transport include:
• Lack of flexibility compared to truck transport. The
pipeline has a fixed alignment and terminus. The land
application site must have a sufficient useful life to
justify the capital expense of the pipeline and pump
static n(s).
• Sufficient sewage sludge volume generation to justify
the initial capital cost. If one or two tank trucks can
do the job instead, truck transport will often be more
cost-effective.
• Need to acquire pipeline right-of-way. Pipeline align-
ments that avoid right-of-way easement problems
should be evaluated. Condemnation, when neces-
sary, is expensive and time-consuming and may
cause problems with community acceptance.
If pipeline transport is selected, the following factors
should be considered when choosing pipeline routes.
Alternate Routes
Preliminary planning should be conducted to reduce the
number of potential pipeline routes. Generally, one route
will be clearly favorable over the others; however, due
to unknown conditions, a certain amount of flexibility
should be maintained until the final design is deter-
mined. Crossings can add significantly to the cost of the
pipeline and complexity of construction. The shortest
distance with the least elevation difference and fewest
crossings should be the primary goal.
Pipeline Design
Pipeline friction losses should be minimized over the
route of the pipeline since they contribute significantly to
pumping requirements. Abrupt changes in slope and
direction should be minimized. Depending on the nature
of the sewage sludge and the characteristics of the soil,
corrosion control features should be incorporated in the
pipeline design. Frequently spaced isolation valves
should be provided to allow shutdown during repair and
in case of pipe failure.
Pumping Facilities
More than one pump station may be needed if the
pipeline distance is long. The number of pump stations
should be balanced with the size and number of pumps
required to determine the most cost-effective combina-
tion. Pumps should be appropriate for the type of sew-
age sludge to be pumped, and standby pumping units
must be provided.
Emergency Operation
Several days storage should be provided in case of
equipment failure. Digesters can be used for this pur-
pose, if available. Standby power should be provided if
only one independent source of electricity to the pump
stations is available. Additional storage may be substi-
tuted for standby power under certain conditions, al-
though continuous operation is preferable.
Excavation Condition Verification
Field tests should be used to establish or verify the
subsurface soil conditions. Borings should be taken af-
ter the pipeline route has been established but prior to
final design. The field tests should be used to isolate
areas where special design considerations are needed.
If highly unusual localized conditions exist, they should
be avoided, if possible, or additional field tests made.
Existing or planned underground utilities should be lo-
cated and field-verified, if possible. If exact locations
cannot be established, the contractor should be held
responsible for locating them during construction.
Acquisition of Right-of-Way
Right-of-way easements must be acquired for pipelines
on private property. This process should be initiated in
the early stages of the project. The preferable method
is to obtain access rights on easements owned or con-
trolled by other utilities when possible, or to negotiate
with landowners. Acquisition is a lengthy, complex pro-
cedure which should be avoided if possible.
14.2.4 Other Transport Methods
Rail car and barge transport are other possible methods
for transporting sewage sludge. These methods are
usually considered only by large cities for long-distance
transport to land application sites. In Chicago, for exam-
ple, sewage sludge has been dried to over 50 percent
solids, barged, and then trucked to land application
sites (Jacobs et al., 1993). For a detailed discussion of
167
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rail and barge transport, refer to Chapter 14 in the
Process Design Manual for Sludge Treatment and Dis-
posal (U.S. EPA, 1979).
14.3 Storage of Sewage Sludge
It is important to note that in the Part 503 regulation, an
activity is considered storage if sewage sludge is placed
on land for 2 years or less. If sewage sludge remains on
land for longer than 2 years for final disposal, this land
area is considered an active sewage sludge unit and the
surface disposal requirements in Part 503 must be met,
unless the sewage sludge preparer can demonstrate
that the land on which the sewage sludge remains is not
an active sewage sludge unit, as discussed in Part
503.20(b).
14.3.1 Storage Requirements
Sewage sludge storage is necessary to accommodate
fluctuations in sewage sludge production rates, break-
downs in equipment, agricultural cropping patterns, and
adverse weather conditions which prevent immediate
application of sewage sludge to the land. Storage can
potentially be provided at either the treatment plant, the
land application site(s), or both. Chapter 15 in the Proc-
ess Design Manual for Sludge Treatment and Disposal
(U.S. EPA, 1979) presents methods for estimating sew-
age sludge storage capacity and describes various stor-
age facilities.
14.3.2 Storage Capacity
Storage capacity associated with land application sites
is based on the volume and characteristics of the sew-
age sludge and on climate considerations. In a 1993
study of 10 POTWs, most had extensive sewage sludge
storage capacities or other systems in place (Jacobs et
al., 1993). Forexample, a facility in Madison, Wisconsin,
has a large storage lagoon system that will soon be
replaced with new storage tanks capable of storing 6
months (18 million gallons) of sewage sludge. In Denver,
Colorado, the Metro Wastewater Reclamation District
(MWRD) currently composts about 10 percent of the
sewage sludge it produces; while composting is more
expensive than direct land application, the MWRD main-
tains the composting facilities to enhance the flexibility
and reliability of the land application program (Jacobs et
al., 1993).
Many states have regulations governing the provision of
storage capacity for sewage sludge at land application
sites, with requirements varying from state to state.
Indiana, for example, requires storage with a minimum
of 90-days capacity at land application sites; Michigan
requires that field storage be less than 7 days unless the
stored sludge is covered and a seepage barrier is pro-
vided; in Oklahoma, storage at a land application site is
not permitted (U.S. EPA, 1990).
14.3.2.1 Effect of Sewage Sludge Volume and
Characteristics on Storage Capacity
Storage capacity is primarily dependent on the amount
of sewage sludge needed at the land application site
and the volume of sludge received from the treatment
works. Storage capacity should be large enough to han-
dle the volume of sludge generated during the longest
projected time interval between applications (Elliott et
al., 1990) and may need to be larger depending on
climatic factors (see below). For agricultural systems,
the time period between applications can range from 3
months to a year, whereas time spans between applica-
tions to forest land may be greater than 1 year (Elliott
etal., 1990).
The characteristics of sewage sludge also affect storage
(e.g., liquid sludge might be stored in tanks, while sludge
solids may be stockpiled). Sewage sludge charac-
teristics vary with source, type of sewage sludge treat-
ment, and retention time. Data on typical quantities and
characteristics of sewage sludge produced from various
treatment processes are presented in Chapter 4.
14.3.2.2 Climate Considerations for Evaluating
Sewage Sludge Storage
The designer of a land application system should con-
sider the following climatic factors:
• Historical precipitation and temperature records for
the application site.
• Regulatory agency requirements pertinent to the land
application of sewage sludge on frozen, snow-cov-
ered, and/or wet soil.
• Ability of the sewage sludge application equipment
being used to operate on wet or frozen soil.
• Drainage characteristics of the application site and
associated effects on the time required after precipi-
tation for the soil to dry sufficiently to accommodate
equipment.
If left uncovered, large volumes of sludge may be ex-
posed to the elements during storage (Elliott et al.,
1990). Therefore, precipitation volume (minus evapora-
tion) must be added to the storage area required for
sewage sludge. In addition, the Part 503 rule sets re-
strictions on the land application of certain types of
sewage sludge to flooded, frozen, or snow-covered
lands (see Chapter 3). Many states also have seasonal
limits on land application of sewage sludge, which
greatly influence storage requirements at land application
sites. These limits generally forbid the application of sew-
age sludge to saturated ground, ice- or snow-covered
ground, or during rainfall (U.S. EPA, 1990).
The effect on wet soils of heavy vehicle traffic transport-
ing sludge from storage to application areas also should
168
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be considered. The weight of vehicles may damage the
soil structure, increase the bulk density of soil, and
decrease infiltration. These changes in the physical
characteristics of soil may increase the potential for soil
erosion and surface runoff (Lue-Hing et al., 1992).
The climatic considerations that affect sewage sludge
storage capacity are greatly influenced by site-specific
factors. A review of land application system designs in
the United States indicates that sewage sludge storage
capacity ranges from a minimum of 30 days in hot, dry
climates up to 200 days in cold, wet climates.
EPA conducted a computer analysis of approximate
storage requirements forwastewater-to-land application
systems in the United States (Loehr et al., 1979), as
shown in Figure 14-4. This information is included in this
manual to show general regional variations in storage
requirements due to climate. For most sewage sludge
land application systems, the actual storage require-
ment will usually exceed the days shown in Figure 14-4.
BASED ON 0 *C (32 *F)
MEAN TEMPERATURE
1.25 CIB/d PRECIPITATION
2.5 cm OF SNOWCOVER
SHADING DENOTES REGIONS WHERE
THE PRINCIPAL CLIMATIC CONSTRAINT
TO APPLICATION OF WASTEWATER
IS PROLONGED WET SPELLS
Figure 14-4. Storage days required as estimated from the use
of the EPA-1 computer program for wastewater-to-
land systems. Estimated storage based only on
climatic factors.
14.3.2.3 Relationship Between Scheduling and
Storage
The majority of existing land application systems in the
United States are applying sewage sludge to privately
owned land. This requires a flexible schedule to conform
with local farming practices. Scheduling limitations will
result from cropping patterns, and typically the designer
will find that much of the agricultural land can only
receive sewage sludge during a few months of the year.
Applications of sewage sludge should be scheduled to
accommodate the growing season of the selected plant
species (Lue-Hing et al., 1992). The Madison, Wiscon-
sin, program (Table 14-3), for example, applies over 80
percent of its sewage sludge to farmland during the
6-month period from May through October (Taylor,
1994).
Land application to forest sites should be scheduled to
conform with tree grower operations and the annual
growth-dormant cycle of the tree species. Land applica-
tion at reclamation sites must be scheduled to conform
with vegetative seeding and growth patterns and also
with private landowners' operational schedules. At all of
these types of sites, adequate storage capacity must be
provided to accommodate the variability in scheduling.
14.3.2.4 Calculation of Sewage Sludge Storage
Capacity Required
A simple method for estimating sewage sludge storage
capacity required involves estimating the maximum
number of days needed to store the volume of sewage
sludge generated. The estimate of the maximum num-
ber of days is based on climate and scheduling consid-
erations discussed in the previous subsections, as well
as a safety factor. Often, the responsible regulatory
agency will stipulate the minimum number of days of
sewage sludge storage that must be provided. Calcula-
tions for this simple approach are shown below:
Assume:
1 . Average rate of dry sewage sludge generated by
POTW is 589 kg/day (1 ,300 Ib/day).
2. Average sewage sludge contains 5 percent solids.
3. One hundred days storage to be provided.
Solution:
1 . 589 kg/day _ ^
u .uo
sewage sludge.
kg/day (26 OOQ |b/day) of |iquid
2. 1 1 ,780 kg/day = 1 1 ,780 L/day (3,116 gal/day) of liquid
sewage sludge produced.
3.11 ,788 L/day x 1 00 days = 1 .2 million L (31 2,000 gal)
of storage required.
A more sophisticated method for calculating sewage
sludge storage requirements is to prepare a mass flow
diagram of cumulative generation and projected cumu-
lative application of sewage sludge to the land applica-
tion site, as shown in Figure 14-5. The figure shows that
the minimum sewage sludge storage requirement for
this site is approximately 1.2 x 106 gal (4.54 x 106 L),
which represents 84 days of sewage sludge storage
volume. The project designer should increase the mini-
mum storage requirement by a safety factor of 20 to 50
percent to cover years with unusual weather and other
contingencies.
Even more accurate approaches can be used to calcu-
late required sewage sludge storage volume. For exam-
ple, if open lagoons are used for sewage sludge storage,
169
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TOTAL ANNUAL SLUDGE
VOLUME GENERATED
LINE A
CUMMULATIVE SLUDGE
VOLUME GENERATED 'X
BYTHEPOTW
SLUDGE
STORAGE
VOLUME
REQUIRED
1.2X106GAL
LINE C, SAME SLOPE
AS LINE A, LOCATE
TANGENT TO LINE B
J F M A
LINEB
CUMMULATIVE SLUDGE
VOLUME APPLIED TO
THE SLUDGE APPLICATION
SITE (S)
METRIC CONVERSION
1 GAL = 3.78 LITERS
Figure 14-5. Example of mass flow diagram using cumulative generation and cumulative sludge application to estimate storage
requirement.
the designer can calculate volume additions resulting
from precipitation and volume subtractions resulting
from evaporation from the storage lagoon surface.
Minimize the number of times the sewage sludge
must be handled (e.g., transferred, stored) because
costs are incurred each time handling occurs.
14.3.3 Location of Storage
In general, the following factors should be considered
when siting sewage sludge storage facilities:
• Maximize the use of potential storage in the existing
sewage treatment plant units. If the treatment plant
has aerobic or anaerobic digestion tanks, it is often
possible to obtain several weeks storage capacity
by separating the digester(s) to increase solids
content and sewage sludge storage. In addition, older
POTWs often have phased-out tanks, sewage sludge
drying beds, and other areas that are idle and
could be used for sewage sludge storage if properly
modified.
• If possible, locate long-term sewage sludge storage
facilities at the POTW site to take advantage of the
proximity of operating personnel, ease of vandalism
control, and the possibility of sewage sludge volume
reduction, which will reduce transportation costs.
14.3.4 Storage Design
Storage capacity can be provided by:
• Stockpiles
• Lagoons
• Tanks, open top or enclosed
• Digesters
It is important to remember that if sewage sludge re-
mains on land (e.g., in stockpiles or lagoons) for longer
than 2 years, the surface disposal requirements in the
Part 503 rule must be met. Chapter 15 of the EPA
Process Design Manual for Sludge Treatment and Dis-
posal (U.S. EPA, 1979) contains a comprehensive dis-
cussion of sewage sludge storage design options and
applicable detention times for each type of storage
structure (see Table 15-1 in that manual) and should be
consulted for more details. The different types of storage
systems are summarized below.
170
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14.3.4.1 Stockpiles
14.4 Land Application Methods
Stockpiling involves the temporary storage of sewage
sludge that has been stabilized and dewatered or dried
to a concentration (about 20 to 60 percent solids) suit-
able for mounding with bulldozers or loaders. The sew-
age sludge is mounded into stockpiles 2 to 5 m (6 to 15
ft) high, depending on the quantity of sewage sludge and
the available land area. Periodic turning of the sewage
sludge helps to promote drying and maintain aerobic
conditions. The process is most applicable in arid and
semiarid regions, unless the stockpiles are covered to
protect against rain. Enclosure of stockpiles may be
necessary to control runoff.
14.3.4.2 Lagoons
Lagoons are often the least expensive way to store
sewage sludge. With proper design, lagoon detention
also provides additional stabilization of the sewage
sludge and reduces pathogens.
14.3.4.3 Tanks
Various types of tanks can be used to store sewage
sludge. In most cases, tanks are an integral part of
sewage sludge treatment processes at a POTW, and the
design for these processes usually includes storage
capabilities. A mobile storage tank (nurse tank) in the
field can serve as a buffer between the transportation
and application of sewage sludge, allowing the opera-
tors to work somewhat independently of one another.
The Madison, Wisconsin, program uses such a system
and as a result has observed a 25 percent increase in
its productivity (Jacobs et al., 1993). Liquid sewage
sludge is transported at the Madison site using 5,500-
gallon vacuum trucks that discharge the sewage sludge
into a 12,000-gallon mobile storage tank located at the
application site. A 3,500-gallon application vehicle with-
draws sewage sludge from the storage tank and injects
the sludge 6 to 8 inches beneath the soil surface. Two
truckloads normally fill one storage tank and application
vehicle (Jacobs et al., 1993).
14.3.4.4 Treatment Plant Digester Capacity
Many sewage treatment plants do not have separate
sewage sludge retention capacity, but rely on portions
of the digester volume for storage. When available, an
unheated sewage sludge digester may provide short-
term storage capacity. In anticipation of periods when
sewage sludge cannot be applied to the land, digester
supernatant withdrawals can be accelerated to provide
storage of sewage sludge for several weeks.
14.4.1 Overview
The technique used to apply sewage sludge to the land
can be influenced by the means used to transport the
sludge from the treatment works to the land application
site. Commonly used methods include:
• The same transport vehicle hauls the sewage sludge
from the treatment works to the application site and
applies the sewage sludge to land.
• One type of transport vehicle, usually with a large
volume capacity, hauls sewage sludge from the treat-
ment works to the application site. At the application
site, the haul vehicle transfers the sewage sludge
either to an application vehicle, into a storage facility,
or both.
• Sewage sludge is pumped and transported by pipe-
line from the treatment works to a storage facility at
the application site. Sewage sludge is subsequently
transferred from the storage facility to an application
vehicle.
Sewage sludge land application methods involve either
surface or subsurface application. Each has advantages
and disadvantages that are discussed in the following
subsections. With all of the application techniques, the
sewage sludge eventually become incorporated into the
soil, either immediately by mechanical means or over
time by natural means.
Sewage sludge is applied either in liquid or dewatered
form. The methods and equipment used are different for
land application of these two types of sewage sludge,
and each has advantages and disadvantages that are
highlighted below.
Regardless of the type of application system chosen at
a land application site, attention must be paid to poten-
tial physical problems of the soil at the site. One study
of sewage sludge land application programs determined
that farmers who participate in such programs are very
concerned about soil compaction (Jacobs et al., 1993).
Programs in Wisconsin, Colorado, and Michigan using
private farmland have found that attention to potential
soil compaction as well as deep tilling the staging areas
when land application is completed is important. Long-
term working relationships with farmers have been en-
hanced in these programs by managing equipment and
field applications to avoid soil compaction (Jacobs et al.,
1993).
14.4.2 Application of Liquid Sewage Sludge
Application of sewage sludge to land in liquid form is
relatively simple. Dewatering processes are not re-
quired, and the liquid sewage sludge can be readily
171
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pumped. Liquid sewage sludge application systems in-
clude:
• Vehicular surface application by:
- Tank truck spreading, or
- Tank wagon spreading
• Subsurface application by:
- Subsurface injection, or
- Plow furrow or disking methods
• Irrigation application by:
- Spray application, or
- Flood irrigation (gravity flooding)
14.4.2.1 Surface Application
Surface application of liquid sewage sludge involves
spreading without subsequent incorporation into the
soil. Surface application of sewage sludge has been
shown to reduce nutrient and soil loss on no-till cropland
that would otherwise occur through surface water runoff
using other application methods. Surface application
may also have similar benefits on conventionally tilled
cropland (Elliott et al., 1990).
Vehicle Types Available
Table 14-5 describes the methods, characteristics, and
limitations of applying liquid sewage sludge by surface
application. Liquid sewage sludge can be spread on the
soil surface using application vehicles equipped with
splash plates, spray bars, or nozzles. Uniform applica-
tion is the most important criterion in selecting which of
the three attachments are best suited to an individual
site. Figure 14-6 depicts a tank truck equipped with
splash plates. Figure 14-7 depicts a tank truck with a
rear-mounted "T" pipe. Forthesetwo methods, application
rates can be controlled either by valving the manifold or
Table 14-5.
Method
Surface Application Methods for Liquid Sewage
Sludge (Cunningham and Northouse, 1981)
Characteristics
Topographical and
Seasonal
Limitations
Tank truck Capacity 500 to more than
2,000 gallons; flotation tires
desirable; can be used with
temporary irrigation set-up;
can achieve a uniform
application rate with pump
discharge.
Farm tank Capacity 500 to 3,000
wagon gallons; wagon flotation tires
desirable; can be used with
temporary irrigation set-up;
can achieve a uniform
application rate with pump
discharge.
Tillable land; not
usable at all times
with row crops or
on very wet ground.
Tillable land; not
usable at all times
with row crops or
on very wet ground.
by varying the speed of the truck. A much heavier appli-
cation will be made from a full truck than from a nearly
empty truck or wagon unless the speed of the truck or
wagon advancing across the field is steadily decreased
to compensate for the steadily decreasing hydraulic
head (U.S. EPA, 1977). Figure 14-8 depicts a spray
nozzle mounted on a tank truck. By spraying the liquid
sewage sludge under pressure, a more uniform cover-
age is obtained.
Hauling a full tank of sludge across the application site
compacts the soil (Elliott et al., 1990). Conveyance of
Figure 14-6. Splash plates on back of tanker truck (U.S. EPA,
1978).
Figure 14-7. Slotted T-bar on back of tanker truck (U.S. EPA,
1978).
Metric conversion factor: 1 gal = 3.78 L
Figure 14-8. Tank truck with side spray nozzle for liquid sludge
surface application (U.S. EPA, 1978).
172
-------
the tank can be eliminated by using a travelling spray
gun connected directly to the sludge delivery vehicle.
Distribution and drift problems can be reduced by using
a "traveling beam" with multiple sprinklers (Elliott et al.,
1990).
14.4.2.2 Subsurface Application
Subsurface application of liquid sewage sludge involves
either subsurface injection or subsurface incorporation
using plow furrow or disking methods. One study found
that the majority of 10 land application programs ana-
lyzed use subsurface injection or surface spreading fol-
lowed by incorporation because these procedures have
proven to be the most effective means of reducing odors
and improving public acceptability of the program (Ja-
cobs et al., 1993). Therefore, the study recommended
the incorporation of sewage sludge into the soil at land
application sites as soon as possible.
Subsurface injection or soil incorporation of liquid sew-
age sludge has a number of advantages over surface
application, including:
• Potential health and nuisance problems generally can
be avoided. The vector attraction reduction require-
ments of Part 503 can be met using these subsurface
methods of land application when sewage sludge or
domestic septage is applied to certain types of land
(see Chapter 3).
• Nitrogen is conserved because ammonia volatiliza-
tion is minimized.
• Public acceptance may be better.
Injection of sewage sludge beneath the soil places a
barrier of earth between the sewage sludge and vectors
such as flies or rodents that could transmit disease (U.S.
EPA, 1992). In addition, when sewage sludge is in-
jected, the soil quickly removes water from the sewage
sludge, which reduces its mobility and odor (U.S. EPA,
1992). As a result, the requirements for vector attraction
reduction in the Part 503 rule can be demonstrated for
certain types of land by injecting the sewage sludge
below the ground. Under this option, no significant
amount of the sewage sludge can be present on the land
surface within 1 hour after injection, and, if the sewage
sludge is Class A with respect to pathogens, it must be
injected within 8 hours after discharge from the patho-
gen-reduction process (see Chapters).
The requirements for vector attraction reduction under
the Part 503 rule also can be demonstrated for certain
types of land by incorporating sewage sludge applied to
the land within 6 hours after application (see Chapter 3).
If the sewage sludge is Class A with respect to patho-
gens, the time between processing and application must
not exceed 8 hours. After application, the sewage sludge
has to be incorporated into the soil within 6 hours. When
applied at agronomic rates, the loading of sewage
sludge solids typically is about 1/200th of the mass of
soil in the plow layer. If mixing is reasonably good, the
dilution of sewage sludge in the soil surface from incor-
poration is equivalent to that achieved with soil injection
(U.S. EPA, 1992).
The 6 hours allowed in the regulation to complete the
incorporation of sewage sludge into the soil should be
adequate to allow for proper incorporation. As a practical
matter, it may be wise to complete the incorporation in
a much shorter time. Clay soils tend to become unman-
ageably slippery and muddy if the liquid sewage sludge
is allowed to soak into the first inch or two of topsoil
(U.S. EPA, 1992).
Some state requirements for the incorporation of sew-
age sludge once it is land applied may be more stringent
than federal requirements. For example, Kentucky re-
quires incorporation of sewage sludge within 2 hours of
application for odor control (U.S. EPA, 1990).
Subsurface injection or soil incorporation of liquid sew-
age sludge also has potential disadvantages, however,
compared to surface application of liquid sewage
sludge, including:
• Potential difficulty in achieving even distribution of the
sewage sludge.
• Higher fuel consumption costs.
Vehicle Types Available
Table 14-6 describes the methods, characteristics, and
limitations of applying liquid sewage sludge by subsur-
face application. Figures 14-9 and 14-10 illustrate equip-
ment specifically designed for subsurface injection of
sewage sludge, which involves tank trucks with special
injection equipment attached. Tanks for the trucks are
generally available with 6,000, 7,500, and 11,000 L
(1,600, 2,000, and 3,000 gal) capacities. Figure 14-11
shows anothertype of unit, atractorwith a rear-mounted
injector unit; sewage sludge is pumped from a storage
facility to the injector unit through a flexible hose at-
tached to the tractor. Discharge flow capacities of 570
to 3,800 L/min (150 to 1,000 gal/min) are used. The
tractor requires a power rating of 40 to 60 hp.
It is not usually necessary to inject liquid sewage sludge
into the soil when the sludge is applied to existing pasture
or hay fields; however, injection systems are available that
can apply liquid sewage sludge to these areas with a
minimum of crop and soil disturbance (see Figure 14-10).
Soil compaction problems still exist when using injec-
tors. The use of a heavy tank in the field can be avoided
by attaching injectors directly to a tractor tool bar. Sludge
can then be pumped to the injectors from a storage area
or nurse truck using an umbilical hose (Elliott et al.,
1990).
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Table 14-6. Subsurface Application Methods for Liquid Sewage Sludge (Keeney et al., 1975)
Method
Characteristics
Topographic and
Seasonal Limitations
Flexible irrigation hose
with plow or disk cover
Tank truck with plow or
disk cover
Farm tank wagon with
plow or disk cover
Subsurface injection
Use with pipeline or tank truck with pressure discharge; hose connected
to manifold on plow or disc.
500-gallon commercial equipment available; sludge discharged in furrow
ahead of plow or disk mounted on rear on four-wheel-drive truck.
Sludge discharged into furrow ahead of plow mounted on tank trailer;
application of 170 to 225 wet Tons/acre; or sludge spread in narrow
band on ground surface and immediately plowed under; application of
50 to 120 wet Tons/acre.
Sludge discharged into channel opened by a chisel tool mounted on
tank truck or tool bar; application rate 25 to 50 wet Tons/acre; vehicles
should not traverse injected area for several days.
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
Tillable land; not usable on
very wet or frozen ground.
Metric conversion factors: 1 gal = 3.78 L, 1 Ton/acre = 2.24 metric tons/hectare
—- a-"4t - * > -,» ?-*-<'S
*f?-^ ••!%•;
Figure 14-9. Tank truck with liquid sludge tillage injectors
(courtesy of Rickel Manufacturing Company).
Figure 14-10. Tank truck with liquid sludge grassland injectors
(courtesy of Rickel Manufacturing Company).
Figure 14-11. Tractor-pulled liquid sludge subsurface injection
unit connected to delivery hose (courtesy of Bris-
coe Maphis Company).
An example of a land application program using injec-
tion is the Madison, Wisconsin, program. The sewage
sludge injection vehicles used in this program have
been modified by increasing the number of injection
shanks to 6 per vehicle and by adding a drag behind the
injectors to smooth the disturbed soil (Jacobs et al.,
1993). Another example is an Arizona program in which
sewage sludge is land applied with a tractor-mounted
injector. The injectors are supplied with sludge through
a hose connected to the pipe system. A second tractor
pulls the hose out of the way as the injecting tractor
traverses the application fields. Sewage sludge is in-
jected in a triple Crosshatch pattern for uniform distribu-
tion (Jacobs et al., 1993).
The plow or disk and cover method involves discharging
the sewage sludge into a narrow furrow from a wagon
or flexible hose linked to a storage facility through a
manifold mounted on the plow or disk; the plow or disk
then immediately covers the sewage sludge with soil.
Figure 14-12 depicts a typical tank wagon with an at-
tached plow. These systems seem to be best suited for
high loading rates, i.e., a minimum of 3.5 to 4.5 t/ha (8
to 10 dry T/ac) of 5 percent slurry.
174
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Figure 14-12a. Tank wagon with sweep shovel injectors (Cun-
ningham and Northouse, 1981).
Figure 14-12b. Sweep shovel injectors with covering spoons
mounted on tank wagon (Cunningham and Nort-
house, 1981).
14.4.2.3 Irrigation Application
Irrigation application of liquid sewage sludge has been
accomplished using spray irrigation and flood irrigation.
Spray irrigation has been used primarily for forest land
applications; its usefulness for agricultural applications
may be limited by cropping schedules and public accep-
tance (see Chapter?). Flood irrigation of sewage sludge
generally has not been successful and is usually dis-
couraged by regulatory agencies.
Spray Irrigation
Spray irrigation has been used to disperse liquid sew-
age sludge on clearcut openings and in forest stands.
Liquid sewage sludge is readily dispersed through spray
systems if properly designed equipment is used. Solids
must be relatively small and uniformly distributed through-
out the sewage sludge to achieve uniform application and
to avoid system clogging. A typical spray application
system consists of the use of a rotary sprayer (rain gun)
to disperse the liquid sewage sludge over the applica-
tion site. The sludge, pressurized by a pump, is trans-
ferred from storage to the sprayer via a pipe system.
Design of the system can be portable or permanent and
either mobile or stationary. Available spray irrigation
systems include (Loehr et al., 1979):
• Solid set, both buried and above ground
• Center pivot
• Side roll
• Continuous travel
• Towline laterals
• Stationary gun
• Traveling gun
The utility of these systems within the application site
depends on the application schedule and management
scheme utilized. All the systems listed, except for the
buried solid system, are designed to be portable. Main
lines for systems are usually permanently buried,
providing protection from freezing weather and heavy
vehicles.
The proper design of sewage sludge spray application
systems requires thorough knowledge of the commer-
cial equipment available and its adaptation for use with
liquid sewage sludge. It is beyond the scope of this
manual to present engineering design data for these
systems, and it is suggested that qualified irrigation
engineers and experienced irrigation system manufac-
turers be consulted.
Figures 14-13, 14-14, and 14-15 illustrate some of the
spray systems listed above.
Flood Irrigation
In general, land application of sewage sludge by flood
irrigation, also known as gravity flooding, has not been
successful where attempted and is discouraged by
regulatory agencies and experienced designers. Prob-
lems arise from (1) difficulty in achieving uniform sew-
age sludge application rates; (2) clogging of soil pores;
and (3) tendency of the sewage sludge to turn septic,
resulting in odors.
14.4.3 Application of Dewatered Sewage
Sludge
Dewatered sewage sludge is applied to land by surface
application techniques. The principal advantages of us-
ing dewatered sewage sludge are:
• Reduced sewage sludge hauling and storage costs.
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Figure 14-13. Center pivot spray application system (courtesy
of Valmont Industries Inc.).
Figure 14-14. Traveling gun sludge sprayer (courtesy of Lind-
say Manufacturing Company).
IRRIGATION
GUN & STAND
BOOSTER
PUMP
3" BALL VALVE
4" PIPELINE
3" LEVER ACTION
VALVE (2)
PLASTIC LINER
Figure 14-15. Diagram of liquid sludge spreading system in forest land utilizing temporary storage ponds (Water Pollution Control
Federation, 1981).
• The ability to apply sewage sludge at higher applica-
tion rates with one pass of the equipment.
Potential disadvantages of applying dewatered sewage
sludge are:
• Generally, substantial modification of conventional spread-
ing equipment is necessary to apply dewatered sludge.
• More operation and maintenance is generally in-
curred in equipment repairs compared to many liquid
sewage sludge application systems.
Table 14-7 describes methods and equipment for apply-
ing dewatered sewage sludge to the land.
Table 14-7. Methods and Equipment for Application of
Dewatered Semisolid and Solid Sludges
Method Characteristics
Spreading Truck-mounted or tractor-powered box spreader
(commercially available); sludge spread evenly on
ground; application rate controlled by PTD and/or
over-trie-ground speed; can be incorporated by
disking or plowing.
Piles Normally hauled by dump truck; spreading and
leveling by bulldozer or grader needed to give
uniform application.
14.4.3.1 Vehicle Types Available
Spreading of dewatered sewage sludge is similar to
surface application of solid orsemisolid fertilizers, lime,
or animal manure. Dewatered sewage sludge cannot be
pumped or sprayed. Spreading is done by box spread-
ers, bulldozers, loaders, or graders, and the sludge is
then plowed or disked into the soil. The box spreader is
most commonly used, with the other three equipment
items generally being used only for sites with high sew-
age sludge application rates.
Figures 14-16 and 14-17 illustrate the specially de-
signed trucks used to spread dewatered sewage sludge.
For small quantities of dewatered sludge, conventional
tractor-drawn farm manure spreaders may be adequate
(Loehr et al., 1979). Surface spreading of dewatered
sludge on tilled land usually is followed by incorporation
of the sludge into the soil. It is not usually necessary to
incorporate dewatered sludge into the soil when the
sludge is applied to existing pasture or hay fields. Stand-
ard agricultural disks or other tillage equipment pulled
by a tractor or bull dozer can incorporate the dewatered
sludge into the soil, such as the disk tiller, disk plow, and
disk harrow (Figures 14-18 and 14-19).
In Denver, Colorado, spreaders were custom-built to
provide a more even application of dewatered sewage
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-16. A 7.2-cubic-yard dewatered sludge spreader
(courtesy of Big Wheels Inc.).
Figure 14-17. Large dewatered sludge spreader (courtesy of BJ
Manufacturing Company).
Figure 14-18. Example of a disk tiller.
Figure 14-19. Example of a disk plow.
sludge than commercially available spreaders (Jacobs
et al., 1993). The district's spreaders have a metering
screw and gauge that allow the operator to achieve
relatively even applications. In addition, the district in-
stalled a heating system on the spreader box, which
allowed the sewage sludge to be spread during the
winter months. Following surface application, the sew-
age sludge at the Denver site is incorporated into the
soil by disking or plowing (Jacobs et al., 1993).
In Sparks, Nevada, dewatered sewage sludge is un-
loaded at the application site into a windrow at the edge
of the spreading area. The sludge unloading area
changes as the spreading area changes, thus avoiding
the development of "hot spots" with extremely high sew-
age sludge loadings (Jacobs et al., 1993). From the
windrow, a front-end loader places the sludge into a
side-slinger manure spreader, which spreads the sludge
onto the field. The same person operates the front-end
loader and the spreader. Fields are spread in sections,
with the length of a section determined by the distance
required to empty a spreader; a spreader swath usually
is approximately 80 feet wide by 200 feet long. The
tractor to which the spreader is attached is equipped
with hydraulic drive to facilitate speed changes. The
side-slinger design enables the tractor and spreader to
travel on ground that has not yet received sludge appli-
cation, thus keeping the equipment clean. At the end of
each day, the field is disked twice to completely cover
the sewage sludge with soil (Jacobs et al., 1993).
14.5 Site Preparation
14.5.1 General
For agricultural land application systems where sewage
sludge is applied to privately owned farms at low agro-
nomic application rates, site modifications are not typi-
cally cost-effective. At forested systems, usually there is
much more forest land available within the local area
than is needed for sewage sludge land application, so
unsuitable land can be avoided rather than modified. In
the case of land application of sewage sludge at recla-
mation sites, extensive site grading and soil preparation
often are necessary. These site preparation costs, how-
ever, are usually borne by the land owner (e.g., mining
company, ore processor, etc.) and not by the municipal-
ity (see Chapter 9 for a discussion of land application of
sewage sludge at reclamation sites).
14.5.2 Protection of Ground Water and
Surface Water Quality
One of the major environmental tasks at a sewage
sludge land application site is the prevention of surface
and subsurface water contamination by constituents in sew-
age sludge. Nitrogen and phosphorus in surface waters and
nitrate in ground water are usually the constituents of most
177
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concern. The Part 503 pollutant limits and agronomic
rate requirement address these water quality concerns.
Good management practices, such as incorporating or
injecting sewage sludge, minimize the amount of sludge
that can come into contact with rain, thus reducing
potential water contamination (Lue-Hing et al., 1992). If
runoff might occur from a land application site, the water
quality of the runoff should be within acceptable limits,
or the water can be detained in a holding structure and
reapplied to land or treated (Lue-Hing et al., 1992).
Ways to reduce potential water contamination include
grading and erosion control, as discussed below.
14.5.3 Grading
The purpose of establishing surface grades is to ensure
that runoff water and/or liquid sewage sludge do not
pond. Design plans should emphasize that depressions
can be filled with soil from adjoining ridges and mounds.
If an excessive amount of filling is required for low areas,
or if sufficient soil is not readily available, field ditches
can be installed and the surfaces warped towards them.
In areas with little or no slope, grades can be established
or increased by grading between parallel ditches with
cuts from the edge of one ditch and fills from the next.
Terraces may be needed to protect lower lands from
surface water runoff that can cause soil erosion. Ter-
races generally are dug across a slope or at the toe of
a slope, with the borrow material diked on the lower side
for efficiency. Diversion terraces generally are graded
and grass-covered so that the collected water may be
delivered at non-erosive flows to a controlled discharge
point.
A number of states have requirements for the maximum
grade allowable at land application sites and for runoff
control (U.S. EPA, 1990). Requirements for runoff con-
trol range from forbidding application on saturated
ground, as in Mississippi, to specifying designs for runoff
control systems (e.g., capacity for a 10-year, 1-hour
storm), as in Texas.
14.5.4 Erosion Control
The measures used to prevent soil erosion include strip
cropping, terraces, grassed waterways, and reduced
tillage systems (e.g., chisel plowing, no-till planting).
Strip cropping involves planting alternating strips (e.g.,
hay and corn) so that when one crop is harvested, soil
erosion from the harvested strips is contained by the
strips that remain vegetated. The strips are alternated
periodically. The presence of vegetation and/or crop
residues on the soil surface is effective in reducing
runoff from steeply sloping soils. For many cropping
systems (e.g., corn, soybeans, small grains), liquid
sludge applied to the surface is incorporated into the soil
by plowing or disking prior to crop planting, further re-
ducing the potential for loss of sludge constituents via
surface runoff. In essence, selection of the proper sludge
application method (surface or incorporation) in con-
junction with currently recommended practices for con-
trol of soil erosion will essentially eliminate the potential
contamination of surface waters or adjacent lands by
sewage sludge constituents.
Every land application site should be designed to mini-
mize soil erosion. The MWRD in Denver, Colorado, for
example, performs soil management practices recom-
mended by the Department of Agriculture Natural Re-
sources Conservation Service (NRCS) and the Consolidated
Farm Service Agency (formerly Agriculture Stabilization
and Conservation Service) to help reduce the potential for
soil erosion. Information on proper slopes, effective con-
servation tillage, and wind erosion techniques for agricul-
tural lands can be obtained from the NRCS.
14.6 Design of Supporting Facilities
The cost of supporting facilities, such as permanent
all-weather access roads and fences, can usually be
justified only for sites with high sewage sludge applica-
tion rates that will be used over a long project life. These
conditions rarely apply to privately owned agricultural
land application sites.
14.6.1 Access Roads
A permanent road should be provided from the public
road system to the land application site. For large sites,
the roadway should be 6.5 to 8 m (20 to 24 ft) wide to
allow for two-way traffic; for smaller sites, a 5 m (15 ft)
wide road should suffice. To provide all-weather access,
the roadway, at a minimum, should be gravel-surfaced,
preferably with asphalt pavement. Grades should not
exceed equipment limitations. For loaded vehicles, up-
hill grades should be less than 7 percent.
14.6.2 Public Access: Site Fencing and
Security
Under the Part 503 rule, public access restrictions apply
to land application sites where sewage sludge meeting
Class B pathogen requirements is applied (see Chapter
3). Access to lands with a high potential for public expo-
sure, such as parks or ballfields, must be restricted for
1 year after sewage sludge application. Examples of
restricted access include remoteness, posting with "no
trespassing" signs, and/or fencing. Access to land with
a low potential for public exposure (e.g., private farm-
land) must be restricted for 30 days after sewage sludge
application.
Depending on the topography and vegetation of the site
and adjoining areas, entrance gates may suffice to pre-
vent unauthorized vehicular access. At some sites, it will
be necessary to construct peripheral fences to restrict tres-
passers and animals. Fencing requirements are influenced
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by the relative isolation of the site. Sites close to resi-
dences will require fencing. Facilities that are in rela-
tively isolated, rural areas may require a less
sophisticated type of fence or only fencing at the en-
trance and other select places to keep unauthorized
vehicles out.
14.6.3 Equipment and Personnel Buildings
Application equipment and staging areas should be
managed at land application facilities in ways that avoid
compaction of soils receiving sewage sludge (Jacobs et
al., 1993). Avoidance of potential compaction problems
will enhance the long-term working relationship between
a treatment works and crop producers.
At larger facilities, or where climates are extreme, build-
ings may be necessary for office space, equipment, and
employees. Where land application sites are operated
throughout the year, some protection from the elements
for employees and equipment may be necessary. Sani-
tary facilities should be provided for both site and haul-
ing personnel. At smaller facilities where buildings
cannot be justified, trailers may be warranted.
14.6.4 Lighting and Other Utilities
If land application operations occur at night, portable
lighting should be provided at the operating area. 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 facility has structures (e.g., employee
facilities, office buildings, equipment repair or storage
sheds) or if the access road is in continuous use, per-
manent security lighting may be needed.
Larger sites may need 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 electrical generator may be used instead of
having power lines run on-site.
Water should be available for drinking, dust control,
washing mud from haul vehicles before entering public
roads, and employee sanitary facilities. Telephone or
radio communications may be necessary since acci-
dents or spills can occur that necessitate the ability to
respond to calls for assistance.
14.7 References
Cunningham, J., and M. Northouse. 1981. Land application of liquid
digested sewage sludge (METROGRO) at Madison, Wisconsin.
In: Seminar proceedings, land application of sewage sludge. Vir-
ginia Water Pollution Control Association, Inc., Richmond, VA.
pp. 111-145.
Elliott, H., B. Dempsey, D. Hamilton, and J. Wolfe. 1990. Land appli-
cation of water treatment plant sludges: Impact and management.
American Water Works Research Foundation, Denver, CO.
Ettlich, W 1976. What's best for sludge transport? Water Wastes
Engin. 13(10):20-23.
Haug, R., L. Tortorici, and S. Raksit. 1977. Sludge processing and
disposal. LA/OMA Project, Whittier, CA.
Jacobs, L., S. Carr, S. Bohm, and J. Stakenberg. 1993. Document
long-term experience of sewage sludge land application pro-
grams. Water Environment Research Foundation, Alexandria, VA.
Keeney, D., K. Lee, and L. Walsh. 1975. Guidelines for the application
of wastewater sludge to agricultural land in Wisconsin. Technical
Bulletin No. 88, Wisconsin Department of Natural Resources,
Madison, Wl.
Loehr, R., W. Jewell, J. Novak, W. Clarkson, and G. Friedman. 1979.
Land application of wastes, Vol. 2. New York, NY: Van Nostrand
Reinhold.
Lue-Hing, C., D. Zenz, and R. Kuchenrither. 1992. Municipal sewage
sludge management: Processing, utilization, and disposal. In:
Water quality management library, Vol. 4. Lancaster, PA: Tech-
nomic Publishing Co.
Taylor, D. June 1994. Revision, projected monthly sludge distribution
for agricultural sludge utilization program, Madison, Wl.
U.S. EPA. 1992. Control of pathogens and vector attraction in sewage
sludge. EPA/625/R-92/013. Washington, DC.
U.S. EPA. 1990. Guidance for writing case-by-case permit require-
ments for municipal sewage sludge. EPA/505/8-90/001. Wash-
ington, DC.
U.S. EPA. 1979. Process design manual for sludge treatment and
disposal. EPA/625/1-79/011. Washington, DC.
U.S. EPA. 1978. Sludge treatment and disposal, Vol. 2. EPA/625/4-
78/012. Cincinnati, OH.
U.S. EPA. 1977a. Cost of land spreading and hauling sludge from
municipal wastewater treatment plants—Case studies. EPA/30/
SW-619. Washington, D.C.
U.S. EPA. 1977b. Transport of sewage sludge. EPA/600/2-77/216.
Washington, DC.
Water Pollution Control Federation. 1981. Design of wastewater and
stormwater pumping stations. In: Manual of practice FD-4. Wash-
ington, DC.
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Chapter 15
Management, Operational Considerations,
and Recordkeeping and Reporting
15.1 Sewage Sludge Management Plans
In accordance with the Clean Water Act of 1987, EPA
must include sludge requirements in NPDES permits to
protect public health and the environment. To determine
appropriate requirements for land application, EPA re-
quests information from the applicant receiving a permit
on current sewage sludge handling and use practices,
and a 5-year sludge operating plan that describes an
applicator's sludge marketing areas and planning pro-
cedures for new sites (U.S. EPA, 1993a). This Sludge
Management Plan must be included with the permit
application. In addition, the Plan acts as a blueprint for
sludge activities (U.S. EPA, 1993a), and fulfills the re-
quirement of 40 CFR Part 501 that both NPDES and
non-NPDES entities prepare a land application plan for
sewage sludge. The major elements of a Sludge Man-
agement Plan are summarized in Figure 15-1.
EPA will discuss current practices and new site operat-
ing procedures outlined in a Sludge Management Plan
with personnel in state environmental programs and
with the USDA Soil Conservation Service and/or State
Extension Service in counties where sludge might be
marketed as part of the permitting process (U.S. EPA,
1993a). Upon approval of a Sludge Management Plan by
EPA, the plan becomes an enforceable part of the permit.
In addition to sludge management plans, all land appli-
cation operation managers should prepare an operation
program, with responsibility clearly defined for its imple-
mentation. Essential elements of the operation program
include:
• Flexible scheduling of sludge transport, storage, and
application activities to accommodate a treatment
works need to remove sludge, as well as design
needs for land application of the sludge to the site(s).
• Design, management, operation, and maintenance of
the sludge transport system to minimize potential nui-
sance and health problems. The system should in-
clude a procedure for rapid response to accidents,
spills, and other emergency conditions that may arise
during routine sludge transport operations.
• Design, management, operation, and maintenance of
the sludge application site(s) and equipment to mini-
mize potential nuisance and health problems. Where
privately owned and operated land is involved (e.g.,
farms, commercial forest land, mined lands), the
owner/operator is a key participant in the overall ap-
plication site management and operation program.
• Recordkeeping, including adequate documentation of
program activities. See Section 15.6 for a discussion
on recordkeeping at land application sites.
• Health and safety, including necessary, routine pro-
cedures for protecting the general public and opera-
tions personnel.
15.2 Part 503 Requirements Affecting
Land Application Site Operation
Under the Part 503 regulation, Class B site restrictions
must be met at land application sites where sewage
sludge meeting Class B pathogen requirements is ap-
plied (U.S. EPA, 1994a). The Class B site restrictions in
Part 503 include restrictions for harvesting crops and
turf, grazing animals, and limiting public access to these
sites. Figure 15-2 describes these restrictions, while
Figure 15-3 includes examples of crops impacted by the
Class B site restrictions. Also, see Chapter 3 for required
Part 503 management practices.
15.3 Nuisance Issues
Minimizing adverse aesthetic impacts of a sewage
sludge land application system will aid in maintaining
public acceptance of the project. Conscientious house-
keeping can help make the difference between public
perception of the operation as a professional endeavor
and public disapproval of the project. The following fea-
tures reflect good housekeeping (Elliott et al., 1990):
• Well maintained, clean vehicles.
• Application and storage areas that are well kept,
clean, and fenced, if necessary.
• Satisfied land owners.
• Well kept records.
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As part of the NPDES permit application, submit to EPA a Sludge
Management Plan (Plan). The Plan includes current sludge
practices and a 5-year sludge operating plan as listed below.
A. A description of the permittee's sludge production and any cur-
rent and known future land application sites.
B. A list of the counties (and states if applicable) where the permit-
tee may want to market or distribute its sludge over the life of
the permit (5 years minimum). A copy of the plan must be sub-
mitted to the respective State Health Department, and should
be submitted to the State Extension Service Office in the coun-
ties where sludge may be marketed.
C. Site selection criteria to be used when identifying new land ap-
plication sites.
D. Site management practices being followed relating to, at a mini-
mum: floodplain, slope, depth to ground water, weather condi-
tions, soil conditions (compaction, permeability, saturated,
frozen, snow-covered), site access, and protection of surface
waters, wetlands, endangered species, and underground drink-
ing water sources at current sites; and operating procedures
(e.g., qualified soils consultant, Soil Conservation Service,
State Extension Service) for annual adjustments and for set-
ting site management practices for future sites.
E. Buffer zones between sludge application sites and: surface wa-
ters, drinking water wells, drainage ditches, property lines, resi-
dences, schools, playgrounds, airports, public roadways, and
any necessary site-specific buffer zones for current sites; and
operating procedures (e.g., qualified soils consultant, Soil Con-
servation Service, State Extension Service) for making annual
adjustments and for setting buffer zones for future sites.
F. Storage provision for sludge during periods when sludge can-
not be land applied.
G. Either Part 503 pollutant concentration limits, or maximum ac-
ceptable total cumulative application rates, expressed as kilo-
grams per hectare (kg/ha) (or annual application rates for
bagged sewage sludge, kg/ha/yr), for arsenic, cadmium, chro-
mium, copper, lead, mercury, molybdenum nickel, selenium, and
zinc, and any other pollutants regulated by the Part 503 rule.
H. Maximum acceptable sludge application rate to assure that the
amount of sludge applied does not exceed the nutrient require-
ments of the particular crop grown on the application site (agro-
nomic rates) for current year crops, and operating procedures
(e.g., by qualified soils consultant, Soil Conservation Service,
State Extension Service) for making annual agronomic rate ad-
justments and for setting agronomic rates for future sites.
I. A description of the pathogen treatment, vector attraction con-
trol, record keeping, monitoring, certifications, and notifications
as required by the 40 CFR Part 503 regulation.
J. Reference to applicable regulations (40 CFR Part 503) and
procedures the permittee intends to use to ensure that the
sludge practices and limits outlined are followed.
K. Information described in 40 CFR 501.15(2) (states may require
additional information).
L. Public notice procedures and procedures for advanced notice to
EPA (at least 60 days) of proposed new land application sites.
M. Procedures, or copies of documents specifying procedures
(e.g., contracts) that will be used to ensure compliance with
this permit and applicable regulations if the permittee contracts
with others for assistance to select and/or manage the land ap-
plication sites itself.
N. Contingency plans that describe sludge disposal options for
any sludge which does not meet the requirements for land ap-
plication or exceeds storage capacity.
O. A statement (e.g., city ordinance) that the permittee will comply
with the Sludge Management Plan, as approved by EPA.
P. A statement that the Plan will be amended to reflect any appli-
cable practices or limits EPA promulgates pursuant to Section
405 of the Act.
Figure 15-1. Sludge Management Plan (U.S. EPA, 1993a).
Restrictions for the harvesting of crops* and turf:
1. Food crops, feed crops, and fiber crops shall not be harvested
until 30 days after sewage sludge application.
2. Food crops with harvested parts that touch the sewage
sludge/soil mixture and are totally above ground shall not be
harvested until 14 months after application of sewage sludge.
3. Food crops with harvested parts below the land surface where
sewage sludge remains on the land surface for 4 months or
longer prior to incorporation into the soil shall not be harvested
until 20 months after sewage sludge application.
4. Food crops with harvested parts below the land surface where
sewage sludge remains on the land surface for less than 4
months prior to incorporation shall not be harvested until 38
months after sewage sludge application.
5. Turf grown on land where sewage sludge is applied shall not
be harvested until 1 year after application of the sewage
sludge when the harvested turf is placed on either land with a
high potential for public exposure or a lawn, unless otherwise
specified by the permitting authority.
Restriction for the grazing of animals:
1. Animals shall not be grazed on land until 30 days after applica-
tion of sewage sludge to the land.
Restrictions for public contact:
1. Access to land with a high potential for public exposure, such
as a park or ballfield, is restricted for 1 year after sewage
sludge application. Examples of restricted access include post-
ing with no trespassing signs, and fencing.
2. Access to land with a low potential for public exposure (e.g.,
private farmland) is restricted for 30 days after sewage sludge
application. An example of restricted access is remoteness.
'Examples of crops impacted by Class B pathogen requirements are
listed in Figure 15-3.
Figure 15-2.
Restrictions for the harvesting of crops and
turf, grazing of animals, and public access on
sites where Class B biosolids are applied.
Harvested Parts That:
Usually Do Not Touch
the Soil/Sewage Usually Touch the Are Below the
Sludge Mixture Soil/Surface Soil/Surface
Peaches
Apples
Oranges
Grapefruit
Corn
Wheat
Oats
Barley
Cotton
Soybeans
Figure 15-3.
Melons
Strawberries
Eggplant
Squash
Tomatoes
Cucumbers
Celery
Cabbage
Lettuce
Examples of crops impacted
Potatoes
Yams
Sweet Potatoes
Rutabaga
Peanuts
Onions
Leeks
Radishes
Turnips
Beets
by site restrictions
for Class B sewage sludge (U.S. EPA, 1994a).
182
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Continuous efforts should be made to avoid or reduce
nuisance problems associated with sludge hauling, ap-
plication, and related operations. Potential nuisances of
concern include odor, spillage, mud, dust, noise, road
deterioration, and increased local traffic, as discussed
below.
15.3.1 Odor
All sludge management systems must consider objec-
tionable odor as a potential problem. Objectionable
odors could result in an unfavorable public reaction and
reduced acceptance of land application practices.
It is important to note that when pathogen reduction and
vector attraction reduction is achieved according to re-
quirements specified in the Part 503 rule (see Chapter
3 fora complete discussion of these requirements), odor
should not pose a problem at land application sites. For
example, injection of sewage sludge beneath the soil
(Option 9 for demonstrating reduced vector attraction of
sewage sludge) places a barrier of earth between the
sewage sludge and vectors. The soil quickly removes
water from the sludge, which reduces the mobility and
odor of the sewage sludge. Odor is usually present at
the site during the injection process, but it quickly dissi-
pates when injection is completed (U.S. EPA, 1992).
Potential for odors also can be reduced or eliminated by:
• Incorporation of sludge as soon as possible after
delivery and application to the site.
• Daily cleaning (or more frequently, if needed) of
trucks, tanks, and other equipment.
• Avoiding sludge application to waterlogged soils or
when other soil or slope conditions would cause
ponding or poor drainage of the applied sludge.
• Use of proper sludge application rates for application
site conditions.
• Avoiding or limiting the construction and use of
sludge storage facilities at the land application site,
or designing and locating the sludge storage facilities
in a way that prevents odor problems. Experience
has shown that sludge storage facilities are a major
cause of odor problems at land application sites.
• Isolation of the sludge application site from residen-
tial, commercial, and other public access areas.
Prevention of odor problems by using the recommenda-
tions listed above is important for public acceptance of
land application programs. If odor problems resulting in
citizen complaints do occur, the project management
should have established procedures for correcting the
problems and responding to complaints.
15.3.2 Spillage
All trucks involved in handling sludge on highways
should be designed to prevent sludge spillage. Liquid
sludge tankers generally do not present a problem. For
sludge slurries (10 to 18 percent solids), specially de-
signed haul vehicles with anti-spill baffles have been
effectively employed. Sludge spillage on-site can gener-
ally be best controlled using vacuum transfer systems.
If mechanical or human errors during transport or at the
application site do result in spillage of sludge, cleanup
procedures should be employed as soon as possible.
Major spills may result from traffic accidents, faulty or
poorly maintained equipment, or inadequate storage
facilities (Elliott et al., 1990). Major spills can be mini-
mized by properly training drivers and applicators; locat-
ing application sites along well maintained roads;
providing adequate storage for equipment so that it is
not exposed to bad weather conditions; properly design-
ing storage facilities; and regularly maintaining equip-
ment (Elliott et al., 1990).
Small, minor spills should also be avoided. Minor spills
can occur as hoses are uncoupled between a nurse
truck and a tank wagon, when equipment is overfilled,
when the seal on a dumptruck tailgate wears out, and
numerous other situations (Elliott et al., 1990). Minor
spills can be prevented with proper equipment mainte-
nance and careful material handling.
15.3.3 Mud
Tracking of mud from the field onto highways, as well as
field or access road rutting by sludge transport or appli-
cator equipment are nuisance concerns. Mud can be a
particularly severe problem in areas with poor drainage,
but can occur at any site during periods of heavy rain or
spring thaws. Choose all-weather site access roads or
modify access roads with gravel or other acceptable
weight-bearing material. To minimize problems with
mud, the following management steps should be con-
sidered:
• Use vehicles with flotation tires.
• Use vehicles with smaller capacity, or temporarily re-
duce volume of sludge being hauled.
• Remove mud tracked on roads.
• Wash down vehicles regularly when moving between
sites to prevent tracking of mud on highways. This
process also improves the public image of sludge
hauling and handling systems and enhances contin-
ued community acceptance.
15.3.4 Dust
Dust movement off-site increases with wind or move-
ments of haul vehicles and equipment. To minimize dust
183
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generation, access roads may need to be graveled,
paved, oiled, or watered.
15.3.5 Noise
Noise levels from use of heavy equipment (e.g., tractors,
subsurface injector vehicles) at land application sites
may be a concern in some communities. In agricultural
areas, noise (and dust) should generally be no worse
than expected from normal farming operations and
should not create problems. In more populated areas,
use of buffer zones and vegetative screening (trees and
shrubs around the site) may be needed to mitigate
public impact.
15.3.6 Road Maintenance
The breakup of roads by heavy sludge hauling vehicles
can be a problem, particularly in northern climates, and
can result in public complaints. Project management
should have provisions to repair roads or a fund avail-
able to help finance cost of road repairs resulting from
project activity.
15.3.7 Selection of Haul Routes
Routes for sludge haul trucks should avoid residential
areas to prevent nuisance caused by truck and air brake
noise, dangers to children, and complaints regarding
frequency of hauling.
15.4 Safety Concerns
Managers of sewage sludge land application systems
have an obligation to maintain safe and secure working
conditions for all personnel and residents, including in-
dividuals working directly with the sludge (e.g., POTW
personnel, sludge haulers, farmers, heavy equipment
operators), as well as persons living or working near an
application site or visiting the site. It is important that
safety rules are written, published, distributed to all em-
ployees, and enforced. A safety training program, cov-
ering all aspects of site safety and proper equipment
operation, as required by OSHA, should be conducted
on a regular basis.
Safety features should be incorporated into every facet
of the land application system design. Certain practices
should be followed routinely to assure safe working
conditions. The official operations program should con-
tain specific safety guidelines for each operation and
feature of the system.
The operation of sludge hauling and application equip-
ment presents the greatest potential for accidents.
Regular equipment maintenance and operational safety
checks should be conducted.
The stability of the soil can present a potential safety
problem, particularly when operating large equipment.
Vehicles should approach disturbed or regraded sites,
muddy areas, or steep slopes cautiously to prevent
tipping or loss of control.
As with any construction activity, safety methods should
be implemented in accordance with Occupational Safety
and Health Administration (OSHA) guidelines. In ac-
cordance with OSHA guidelines, the following precau-
tions and procedures should be employed for sludge
land application projects:
• A safety manual should be available for use by em-
ployees, and all employees should be trained in all
safety procedures.
• Appropriate personal safety devices, such as hard-
hats, gloves, safety glasses, and footwear, should be
provided to employees.
• Appropriate safety devices, such as rollbars, seat-
belts, audible reverse warning devices, and fire ex-
tinguishers, should be provided on equipment used
to transport, spread, or incorporate sludge.
• Fire extinguishers should be provided for equipment
and buildings.
• Communications equipment should be available on-
site for emergency situations.
• Work areas and access roads should be well marked
to avoid on-site vehicle mishaps.
• Adequate traffic control should be provided to pro-
mote an orderly traffic pattern to and from the land
application site to maintain efficient operating condi-
tions and avoid traffic jams on local highways.
• Public access to the sludge application site should
be controlled. The extent of the control necessary will
depend on the sludge application practice being
used, the time interval since sludge was last applied,
and other factors (see applicable process design
chapters 7 through 9). In general, public access to
application sites should be controlled during sludge
application operations and for an appropriate time
period after the sludge is applied.
15.4.1 Training
It is important for land application facilities to employ well
trained personnel. Qualified personnel can be the differ-
ence between a well organized, efficient operation and
a poor operation. New employees should not only learn
the tasks required for their positions, but also under-
stand the purposes and importance of the overall land
application operation. Equipment should be operated
only by fully trained and qualified operators.
A training program should be conducted for site person-
nel by the engineer who designed the land application
program or someone well acquainted with the operation.
184
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Training programs should incorporate the following (Elliott
etal., 1990):
• All aspects of operation, from sludge production to
growth of crops, should be discussed.
• Equipment operators should fulfill licensing require-
ments.
• Applicators should be taught to calculate application
rates and calibrate equipment.
• Good housekeeping should be stressed during all
phases of training.
15.5 Health Concerns
15.5.1 General
A discussion of pathogens and vectors that may be
associated with sewage sludge is contained in Chapters
3 and 4. Although bacteria, viruses, and parasites are
generally present in sewage sludge, the requirements in
Subpart D of the Part 503 regulation protect public
health and the environment through requirements de-
signed to reduce the density of organisms in sewage
sludge to below detectable levels, or, through a combi-
nation of organism reduction and site restrictions, allow
the environment to further reduce organisms to below
detectable levels (U.S. EPA, 1992).
In addition, research by EPA and others has shown no
significant health problems for personnel who are in
contact with sewage sludge on a regular basis at
POTWs or land application sites (Burge and Marsh,
1978; Clark et al., 1980). Furthermore, epidemiological
studies have shown no significant health problems for
people living or working close to sites receiving land
applied sewage sludge or wastewater (U.S. EPA, 1985;
Kowal, 1983; Pahren et al., 1979).
15.5.2 Personnel Health Safeguards
It is recommended that project management include
health safeguards for personnel involved with sludge
transport and handling, including:
• Provide regular typhoid and tetanus inoculations and
poliovirus and adenovirus vaccinations.
• Limit direct contact with aerosols as much as possible
where liquid sludge application techniques are used.
• Encourage proper personal hygiene.
• Provide annual employee health checkups.
• Record reported employee illnesses; if a pattern
(trend) of illnesses potentially associated with sludge
pathogens develops, investigate and take appropriate
action.
15.6 Recordkeeping and Reporting
15.6.1 General
The Part 503 regulation requires that certain records be
kept by the person who prepares sewage sludge for land
application and the person who applies sewage sludge
to the land. The regulation defines the person who pre-
pares sewage sludge as "either the person who gener-
ates sewage sludge during the treatment of domestic
sewage in a treatment works or the person who derives
a material from sewage sludge." This definition covers
two types of operations—those that generate sewage
sludge and those that take sewage sludge after it has
been generated and change the quality of the sewage
sludge (e.g., blend or mix it with another material) prior
to use or disposal. Any time the sewage sludge quality
(e.g., pollutant concentrations, pathogens levels, orvec-
tor attraction characteristics) is changed, the person
responsible for the change is defined as a person who
prepares sewage sludge. Recordkeeping requirements
for preparers and appliers of sewage sludge are sum-
marized in Table 15-1, and specific requirements are
discussed in Sections 15.6.2 and 15.6.3. Dewatering
sewage sludge is not considered to be changing the
quality of the sewage sludge.
Preparers and appliers of sewage sludge should be
aware that failure to keep adequate records is a violation
of the Part 503 regulation and subject to administrative,
civil, and/or criminal penalty under the Clean Water Act.
15.6.2 Part 503 Recordkeeping
Requirements for Preparers of
Sewage Sludge
Part 503 requires the person who prepares sewage
sludge to evaluate sewage sludge quality, maintain re-
cords, submit compliance reports (for some preparers),
and distribute sludge quality information to subsequent
preparers and appliers who need the information to
comply with the other requirements of the regulation.
With respect to pollutants, the Part 503 regulation re-
quires the preparerto maintain records documenting the
concentration of regulated pollutants in the sewage
sludge. With respect to pathogens and vector attraction,
the records must describe how the pathogen and vector
attraction reduction requirements were met (if one of the
vector attraction reduction options 1 through 8 was met,
see Chapter 3) and include a signed certification of their
achievement. The regulation specifies that records be
maintained for a period of at least 5 years.
U.S. EPA (1993b) presents a detailed discussion of the
recordkeeping responsibilities for preparers of sewage
sludge under Part 503.
185
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Table 15-1. Part 503 Recordkeeping and Reporting Requirements (U.S. EPA, 1994a)
Type of Sewage
Sludge
Records That Must Be Kept
Person Responsible
for Recordkeeping
Preparer
Applier
Records That Must
Be Reported3
EQ Sewage Sludge
Pollutant concentrations
Pathogen reduction certification and description
Vector attraction reduction certification and description
PC Sewage Sludge
CPLR Sewage Sludge
APLR Sewage Sludge
Pollutant concentrations /
Management practice certification and description
Site restriction certification and description (where
Class B pathogen requirements are met)
Pathogen reduction certification and description /
Vector attraction reduction certification and description /
Pollutant concentrations /
Management practice certification and description
Site restriction certification and description (if Class
B pathogen requirements are met)
Pathogen reduction certification and description /
Vector attraction reduction certification and description /
Other information:
- Certification and description of information
gathered (information from the previous applier,
landowner, or permitting authority regarding the
existing cumulative pollutant load at the site from
previous sewage sludge applications)
- Site location
- Number of hectares
- Amount of sewage sludge applied
- Cumulative amount of pollutant applied (including
previous amounts)
- Date of application
Pollutant concentrations /
Management practice certification and description /
Pathogen reduction certification and description /
Vector attraction reduction certification and description /
The AWSAR for the sewage sludge /
/b
/
/c
/
/c
/d
/d
/d
a Reporting responsibilities are only for treatment works with a design flow rate equal to or greater than 1 mgd, treatment works that
serve a population of 10,000 or greater, and Class I treatment works.
3 The preparer certifies and describes vector attraction reduction methods other than injection and incorporation of sewage sludge into the soil.
The applier certifies and describes injection or incorporation of sewage sludge into the soil.
: Records that certify and describe injection or incorporation of sewage sludge into the soil do not have to be reported.
^ Some of this information has to be reported when 90 percent or more of any of the CPLRs is reached at a site, if the applier is a Class I treatment
works, a treatment works serving a population of 10,000 or more, or a treatment works with a 1 mgd or greater design flow.
15.6.2.1 Records of Pollutant Concentrations
The preparer is responsible for documenting the sam-
pling and analysis of pollutant concentrations in sewage
sludge; to demonstrate this, the records outlined in Fig-
ure 15-4 should be maintained.
When sewage sludge or material derived from sewage
sludge that is destined for land application does not
meet the pollutant concentration limits in Chapter 3,
Table 3-4, additional records must be kept to demon-
strate compliance with either the cumulative pollutant
loading rate limits or the annual pollutant loading rate
limits outlined in Table 3-4, as appropriate.
If the preparer plans to sell or give away the sewage
sludge in a bag or other container for application to the
land, he or she must develop and retain the following
additional records (if the sewage sludge does not meet
"exceptional quality" criteria, as discussed in Chapter 3):
• Calculation of an annual whole sludge application
rate (AWSAR) that will not exceed the annual pollut-
ant loading rate limits in Chapter 3, Table 3-4.
• A copy of the label or information sheet provided to
persons who will land apply the sewage sludge.
15.6.2.2 Certification of Pathogen Reduction
The Part 503 regulation requires the maintenance of
records that include a certification by the preparer that
the pathogen requirements were met and a description
of how compliance was achieved. The general certifica-
tion statement that must be used is provided in Figure
15-5. Usually, the description should explain the treat-
ment process for pathogen reduction and be supported
186
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by analytical results for pathogens and indicator organ-
isms and log books documenting operational parame-
ters for sludge treatment units. The following paragraphs
discuss the types of records used to demonstrate com-
pliance for each pathogen reduction alternative. A discus-
sion of Class A and Class B alternatives is provided in
Chapters.
Class A Alternatives
Table 15-2 summarizes the recordkeeping requirements
for each Class A alternative.
Alternative 1: Thermally Treated Sewage Sludge
This alternative requires that sludge treatment units be
operated to maintain the sludge at a specific tempera-
ture for a specific period of time. To demonstrate com-
pliance with the operational parameters, the preparer
should check the temperature in the sludge treatment
unit(s) and record it to demonstrate that the sludge was
Parameters: Pollutant Concentrations (metals), Salmonella
sp. or Fecal Coliform bacteria, Percent Solids, Enteric
Viruses and Viable Helminth Ova (for certain pathogen
reduction alternatives)
• Sampling Records. Date and time of sample collection,
sampling location, sample type, sample volume, name of
sampler, type of sample container, and methods of
preservation, including cooling.
• Analytical Records. Date and time of sample analysis,
name of analyst, and analytical methods used.
• Raw Data. Laboratory bench sheets indicating all raw data
used in the analyses and the calculation of results (unless
a contract laboratory performed the analyses for the
preparer).
• Name of contract laboratory, if applicable.
• QA/QC. Sampling and analytical quality assurance/quality
control (QA/QC) procedures.
• Analytical results expressed in dry weight.
Figure 15-4. Required Records for Preparers of Sewage Sludge
to Document Sampling and Analysis (U.S. EPA,
1993b).
held at a constant temperature for the required number
of days. If the temperature is not recorded continuously,
it should be checked and recorded during each work
shift or at least twice a day. The objective is to obtain
temperature readings that are representative of the tem-
perature maintained throughout the treatment process.
In addition, records should document the detention time
of the sludge in the treatment unit, the daily input of
sludge, and the withdrawal of supernatant and proc-
essed sludge from the treatment unit. The size (gallons)
of the unit(s) should also be documented.
This alternative also requires documentation of monitor-
ing for either Salmonella sp. bacteria or fecal coliform in
sewage sludge at the time of use. To this end, the
preparer should keep the records outlined in Figure 15-4
documenting sampling and analysis.
Alternative 2: Sewage Sludge Treated in a High pH-
High Temperature Process
Alternative 2, like Alternative I, requires the analysis of
sludge quality and the evaluation of operating parame-
ters. As with Alternative 1, the sludge must be monitored
for either Salmonella sp. bacteria or fecal coliform. Use
of this alternative requires that operating logs be kept
that document pH, temperature, residence time, and
percent total solids. The temperature of the sewage
sludge should be checked and recorded to document it
is above 52°C for 12 continuous hours during the re-
quired 72-hour holding period. If the temperature is not
continuously monitored, it should be checked hourly
when feasible. At a minimum, it should be recorded at
the beginning, middle, and end of treatment. Similarly,
the pH of the sewage sludge should be recorded at the
beginning, middle, and end of the required 72-hour hold-
ing period. The percent total solids also should be de-
termined for each batch. The preparer must keep the
records outlined in Figure 15-4 to document that sludge
was analyzed at the time of use or disposal for either
Salmonella sp. bacteria or fecal coliform at the fre-
quency specified in Chapter 3, Table 3-15.
"I certify under penalty of law, that the [insert each of the following requirements that are met: Class A or Class B pathogen
requirements, vector attraction reduction requirements, management practices, site restrictions, requirements to obtain information]'m
[insert the appropriate section number/s in Part 503 for each requirement met] have/have not been met. This determination has been
made under my direction and supervision in accordance with the system designed to ensure that qualified personnel properly gather
and evaluate the information used to determine that the requirements have been met. I am aware that there are significant penalties
for false certification, including the possibility of fine and imprisonment."
Signature
Date
Note: The exact language of the certification should be tailored to accurately describe which requirements have been met and which
have not been met, when applicable.
Figure 15-5. Certification statement required for recordkeeping.
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Table 15-2. Recordkeeping Recommendations for Class A Pathogen Reduction Alternatives (U.S. EPA, 1993b)
Alternative Al— Time and Temperature
• Analytical results for density of Salmonella sp. bacteria or fecal coliform (most probable number)
• Sludge temperature (either continuous chart or two readings per day, at least one per shift)
• Time (days, hours, minutes) temperature maintained
Alternative A2— Alkaline Treatment
• Analytical results for density of Salmonella sp. bacteria or fecal coliform (most probable number)
• Sludge pH (beginning, middle, and end of treatment)
• Time (hours) pH maintained above 12 (at least 72 hours)
• Sludge temperature (beginning, middle, and end of treatment and hourly to demonstrate 12 hours above 52°C)
• Percent solids in sludge after drying (at least 50 percent)
Alternative A3— Analysis and Operation
• Analytical results for density of Salmonella sp. bacteria or fecal coliform (most probable number)
• Analytical results for density of enteric viruses (pkque forming unit/4 grams total solids) prior to pathogen
reduction and, when appropriate, after treatment
• Analytical results for density of viable helminth ova (number/4 grams total solids) prior to pathogen reduction
and, when appropriate, after treatment
• Values or ranges of values for operating parameters to indicate consistent pathogen reduction treatment
Alternative A4— Analysis Only
• Analytical results for density of Salmonella sp. bacteria or fecal coliform (most probable number)
• Analytical results for density of enteric viruses (plaque forming unit/4 grams total solids)
• Analytical results for density of viable helminth ova (number /4 grams total solids)
Alternative AS— Processes to Further Reduce Pathogen
• Heat Drying
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Moisture content of dried sludge < 10 percent
- Logs documenting temperature of sludge particles
or wet bulb temperature of exit gas exceeding 80 °C
(either continuous chart or two readings per day, at
least one per shift)
• Thermophilic Aerobic Digestion
- Analytical results for density of Salmonella sp.
bacteria or fecal coh'form (most probable number)
- Logs documenting temperature maintained at 55-
60 C for 10 days (either continuous chart or two
readings per day, at least one per shift)
• Heat Treatment
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Logs documenting sludge heated to temperatures
greater than 180°C for 30 minutes (either
continuous chart or three readings at 15 minute
intervals)
• Pasteurization
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Temperature maintained at or above 70° C for at
least 30 minutes (either continuous chart or two
readings per day, at least one per shift)
s{PFRP)
• Composting
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Description of composting method
- Logs documenting temperature maintained at or
above 55 °C for 3 days if within vessel or static
aerated pile composting method (either continuous
chart or two readings per day, at least one per
shift)
- Logs documenting temperature maintained at or
above 55°C for 15 days if windrow compost
method (minimum of two readings per day, at least
one per shift)
- Logs documenting compost pile turned at least five
times per day, if windrow compost method
• Gamma Ray Irradiation
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Gamma ray isotope used
- Gamma ray dosage at least 1 .0 megarad
- Ambient room temperature log (either continuous
chart or two readings per day, at least one per
shift)
• Beta Ray Irradiation
- Analytical results for density of Salmonella sp.
bacteria or fecal coliform (most probable number)
- Beta ray dosage at least 1 .0 megarad
- Ambient room temperature log (either continuous
chart or two readings, at least one per shift)
Alternative A6— PFRP Equivalent
• Operating parameters or pathogen levels as necessary to demonstrate equivalency to the PFRP
• Analytical results for density of Salmonella sp. bacteria or fecal coh'form (most probable number)
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Fecal Coliform/Safmone/te sp. Bacteria
AND
Enteric Viruses
AND
Viable Helminth Ova
Sample sludge after pathogen
reduction treatment and at the time
of use or disposal and analyze for
either fecal coliform OR Salmonella
sp. bacteria.
S
Fecal Coliform
analytical results
show density less
than 1,000 MPN"
per gram of total
solids (DW).
Sludge is Class A
_ for bacteria until
next monitoring
interval.
OR
^X
Salmonella sp.
Bacteria
analytical results
show density less
than 3 MPN per
four grams of total
solids.
|
Sludge is Class A
for bacteria until
next monitoring
interval.
Sample sludge before pathogen
reduction treatment and analyze for
enteric viruses.
OR
Analytical results
show density less
than 1 PFU+ per
4 grams of total
solids.
Analytical results
show density
greater than or
equal to 1 PFU
per 4 grams of
total solids.
E
Sludge is Class A
for enteric viruses
until next
monitoring
interval.
Begin pathogen
reduction «
treatment and
record operating
parameters.
Sample sludge before pathogen
reduction treatment and analyze for
viable helminth ova.
OR
Analytical results
show density less
than 1 per 4
grams of total
solids.
Analytical results
show density
greater than or
equal to 1 per 4
grams of total
solids.
E
* MPN = Most probable number
t PFU = Plaque-forming unit
Sludge is Class A
for viable
helminth ova until
next monitoring
interval.
Begin pathogen
reduction
treatment and
record operating
parameters.
\
F
Monitor sludge
again after
pathogen
reduction
treatment.
After demonstration, enteric
viruses no longer need to be
monitored if records
demonstrate that the operating
parameters of the pathogen
reduction treatment are
consistent with parameters
used in the demonstration.
After demonstration, enteric
viruses no longer need to be
monitored if records
demonstrate that the operating
parameters of the pathogen
reduction treatment are
consistent with parameters
used in the demonstration.
Figure 15-6. Pathogen reduction alternative 3—analysis and operation (U.S. EPA, 1993b).
Alternative 3: Sewage Sludge Treated in Other
Processes
Alternative 3, like the first two alternatives under Class
A, utilizes a combination of sludge quality analysis and
documentation of operating parameters. In addition to
monitoring for either fecal coliform or Salmonella sp.
bacteria under this alternative, preparers must monitor
for enteric viruses and viable helminth ova. If the
preparer follows the steps outlined in Figure 15-6, he or
she can substitute documentation of operating parame-
ters for periodic analysis of enteric viruses and viable
helminth ova (U.S. EPA, 1993b). Regardless of how the
preparer demonstrates compliance with the enteric virus
and viable helminth ova requirement, the final sludge
must be sampled and analyzed at the time of use for
either fecal coliform or Salmonella sp. bacteria accord-
ing to the frequency specified in Chapter 3, Table 3-15.
The preparer must maintain the records outlined in Fig-
ure 15-4 to document sludge sampling and analysis
before and after pathogen reduction treatment. These
records also must define the values used for operating
parameters between the before- and after-treatment
sludge analyses. If operating parameters are substituted
for periodic sludge monitoring, records must also docu-
ment that these values are maintained consistently. The
specific operating parameters that must be recorded to
demonstrate compliance may vary depending on the
particular pathogen reduction process used (e.g., com-
posting, pasteurization).
Alternative 4: Sewage Sludge Treated in Unknown
Processes
Alternative 4 relies solely on the analysis of sewage
sludge for pathogens (i.e., Salmonella sp. bacteria, en-
teric viruses, and viable helminth ova) and indicator
organisms (i.e., fecal coliform) to demonstrate pathogen
reduction. Records must document that these parame-
ters were sampled and analyzed at least as often as
specified in the Part 503 regulation (see Chapter 3,
189
-------
Table 3-15). The preparer should keep the records out-
lined in Figure 15-4 for each sampling event.
Alternative 5: Use of a Process to Further Reduce
Pathogens (PFRP)
This alternative requires a combination of sludge analy-
sis for either fecal coliform or Salmonella sp. bacteria
and documentation of operating parameters. The spe-
cific operating parameters that must be evaluated are
defined by the particular PFRPs. Table 15-2 outlines the
seven different PFRPs and the specific operating pa-
rameters for each. Records should include a descrip-
tion of the pathogen reduction process, documentation
of sampling and analysis of the sludge for fecal coliform
or Salmonella sp. bacteria (see Figure 15-4), and log
books documenting proper operation of pathogen re-
duction processes.
Alternative 6: Use of a Process Equivalent to a PFRP
Alternative 6 requires a combination of sludge analysis
and documentation of operating parameters. As with the
other Class A alternatives, the sludge must be monitored
for either fecal coliform or Salmonella sp. bacteria. Al-
ternative 6 requires sewage sludge to be treated in a
process equivalent to a PFRP, as determined by the
permitting authority. The permitting authority should in-
dicate appropriate information that has to be kept. The
records could include temperature in sludge treatment
units, retention time, pH, solids or moisture content, and
dissolved oxygen (DO) concentration.
Table 15-3. Recordkeeping Requirements for Class B Pathogen Reduction Alternatives (U.S. EPA, 1993b)
Alternative Bl—Fecal Coliform Count
Number of samples collected during each monitoring event
Analytical results for density of fecal coliform for each sample collected
Alternative B2—Processes to Significantly Reduce Pathogens (PSRP)
• Aerobic Digestion
- Dissolved oxygen concentration
- Mean residence time of sludge in digester
- Logs showing temperature was maintained for sufficient period of time (ranging from 60 days at 15°C to
40 days at 20°C) (continuous charts or two readings per day, at least one per shift)
• Air Drying
- Description of drying bed design
- Drying time in days
- Daily average ambient temperature
• Anaerobic Digestion
- Mean residence time of sludge in digester (between 15 days at 35"C to 55°C and 60 days at 20DC)
- Temperature logs of sludge in digester (continuous charts or two readings per day, at least one per shift)
• Composting
- Description of composting method
- Daily temperature logs documenting sludge maintained at 40° C for 5 days (either continuous chart or two
readings per day, at least one per shift)
- Hourly readings showing temperature exceeded 55°C for 4 consecutive hours
• Lime Stabilization
- pH of sludge immediately and then 2 hours after addition of lime
Alternative B3—PSRP Equmdent
• Operating parameters or pathogen levels as necessary to demonstrate equivalency to PSRP
190
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Class B Alternatives
Table 15-3 summarizes the recordkeeping requirements
for each Class B alternative.
Alternative 1: Monitoring of Fecal Conform
Alternative 1 requires the analysis of the sewage sludge
for fecal coliform. In addition to maintaining the records
outlined in Figure 15-4 to document compliance with the
fecal coliform level, the preparer should maintain the
calculation of the geometric mean of the seven samples
analyzed under this alternative (see Alternative 1 in
Chapter 3).
Alternative 2: Use of a Process to Significantly Reduce
Pathogens (PSRP)
This alternative requires a combination of sewage
sludge analysis and documentation of operating pa-
rameters. As with the PFRP alternative, the specific
operating parameters that must be evaluated vary de-
pending on the sludge treatment process used, as listed
in Table 15-3. Records should include a description of
the pathogen reduction process and log books docu-
menting regular and frequent evaluations of the operat-
ing parameters.
Alternative 3: Use of a Process Equivalent to a PSRP
Alternative 3 requires sewage sludge to be treated in a
process equivalent to a PSRP, as determined by the
permitting authority. The permitting authority should
have specified the appropriate records to demonstrate
compliance with this alternative. The records could in-
clude temperature in sludge treatment units, retention
time, pH, solids or moisture content, and DO concentra-
tion.
15.6.2.3 Records of Vector Attraction Reduction
When sewage sludge is land applied, the Part 503
regulation requires a certification (see Figure 15-5) that
the vector attraction reduction requirements were met
and a description of how these requirements were
achieved. The description should be supported by docu-
mentation of process controls for treatment processes
that achieve vector attraction reduction. As with the
pollutant and pathogen records, this documentation
must be kept for 5 years.
There are 10 options to comply with the vector attraction
reduction requirements for land application. The first
eight apply to the sewage sludge and are performed by
the preparer (the final two are met at the land application
site). These eight options are referred to as the sludge
processing options and involve sludge treatment to re-
duce vector attraction characteristics. They are per-
formed by preparers during or immediately after
pathogen reduction. Each of these processing options
is discussed in Chapter 3; the related records required
are described below.
Option 1: Reduction in Volatile Solids Content
Under this option the preparer must demonstrate that
the volatile solid concentrations in sewage sludge are
reduced by 38 percent between the raw sludge and the
sewage sludge that is used or disposed. The preparer
needs to maintain records on the volatile solids content
(mg/kg) of the raw sludge and the sewage sludge that
is used or disposed, and the calculation of volatile solids
reduction. While most preparers evaluate these pa-
rameters regularly to document constant process opera-
tion, records must show that volatile solids reduction was
evaluated at least as frequently as specified in Table 3-15
in Chapter 3.
Option 2 and 3: Additional Digestion of Anaerobi-
cally and Aerobically Digested Sewage Sludge
Options 2 and 3 are methods to demonstrate that vector
attraction reduction is achieved even though 38 percent
volatile solids reduction was not attained (as required
under Option 1). The following records demonstrate that
options 2 and 3 are met:
• A description of the bench-scale digester and its
operation.
• The time (days) that the previously digested sludge
sample was further digested in the bench-scale
digester.
• The temperature (degrees Celsius) maintained in the
bench-scale digester for the time (days) the sample
was being further digested; the temperature should
either be recorded continuously or it should be
checked and recorded during each work shift or dur-
ing at least two well-spaced intervals during each day.
• Volatile solids concentration of the sewage sludge in
mg/kg before and after bench-scale digestion.
Option 4: Specific Oxygen Uptake Rate (SOUR) for
Aerobically Digested Sewage Sludge
The preparer should perform the SOUR test and record
the following information to demonstrate compliance un-
der this option:
• Dissolved Oxygen (DO) readings of the sludge taken
at 1-minute intervals over a 15-minute period or until
the DO is reduced to 1 mg/L, and the average DO
value used in the SOUR calculation.
• Calibration records for the DO meter.
• Total solids determination for the sludge in g/L.
• Temperature (degrees Celsius) taken at the begin-
ning and end of the procedure.
191
-------
• Temperature correction to 20°C, if other temperatures
are used.
• Calculation of SOUR using the following equation:
SOUR =
,. , . , .DO mg/L
oxygen consumption rate per minute ( r-2—)
total solids (g/L)
(60 min/hour)
While most preparers evaluate this parameter regularly
to document constant process operation, the records
must demonstrate that the SOUR was evaluated at least
as frequently as specified in Chapter 3, Table 3-15.
Option 5: Aerobic Processes at Greater Than 40°C
Under this option, the preparer should record the follow-
ing information to demonstrate compliance:
• Sludge residence time.
• Temperature (degrees Celsius) of the sewage sludge;
the temperature should either be recorded continu-
ously or checked and recorded at least once per work
shift or at least twice a day over a 14 day period.
Option 6: Addition of Alkali Material
The preparer should maintain the following records to
document alkaline treatment under this option:
• pH (standard units) recorded at least at 0-, 2-, and
24-hour intervals of treatment.
• Duration of time (hours) that pH is maintained at or
above specified minimum levels.
• Amount (pounds or gallons) of alkali material added.
• Amount of sludge treated (e.g., gallons, kilograms).
Options 7 and 8: Moisture Reduction
Under these options, the preparer should determine
percent total solids for each batch of sludge and keep
the following records to demonstrate compliance:
• Results of solids analysis of sewage sludge prior to
mixing with other material (as dry weight) expressed
as percent of final sludge.
• Presence of unstabilized solids generated during pri-
mary treatment.
Records should demonstrate that the analysis of per-
cent total solids was performed at least as frequently as
specified in Chapters, Table 3-15.
15.6.3 Part 503 Requirements for Appliers of
Sewage Sludge
For Part 503 requirements for appliers of sewage
sludge, see the Land Application of Sewage Sludge—
A Guide for Land Appliers on the Recordkeeping and
Reporting Requirements of the Federal Standards for
the Use and Disposal of Sewage Sludge Management
in 40 CFR Part 503 (U.S. EPA, 1994b).
15.6.4 Notification Requirements for Preparers
and Appliers of Sewage Sludge
When sewage sludge is prepared for land application in
bulk form or sold or given away in a bag or other
container for application to the land, the preparer must
inform the applier of the sewage sludge quality. The
notification requirements are different if the sludge is
sold or given away in a bag or other container rather
than being land applied in bulk, as described below. The
notice and necessary information requirement does not
apply when the sewage sludge or the material derived
from sewage sludge meets the "exceptional quality cri-
teria" discussed in Chapter 3.
15.6.4.1 Bulk Sewage Sludge
When bulk sewage sludge that is not "exceptional qual-
ity" is prepared for land application, both the preparer
and the land applier have notification requirements. The
preparer must provide the following sewage sludge
quality information to the land applier:
• Pollutant concentrations.
• Nitrogen concentration (TKN, ammonia, and nitrate
nitrogen).
• Pathogen reduction level achieved (Class A or Class B).
• Vector attraction reduction option used (Options 1-8).
• Required management practices and recordkeeping.
The land applier must have this information to comply
with the Part 503 regulation when land applying the
sewage sludge. If the pollutants do not meet the pollut-
ant concentration limits in Chapter 3, Table 3-4, then the
land applier must track the cumulative pollutant loading
rates. If a Class B pathogen reduction alternative was
used, then the land applier must ensure that the site
restrictions are met. If the preparer did not perform one
of the sludge processing vector attraction reduction op-
tions (Options 1-8), then the land applier must perform
one of the sludge management vector attraction reduc-
tion options (Options 9-10).
The land applier is also responsible for providing the
land owner or lease holder of the land notice and nec-
essary information to comply with the Part 503 require-
ments. For example, if the sludge met Class B pathogen
reduction requirements, then the land owner or lease
holder must be informed of the associated site use and
access restrictions. If the land applier is tracking the
cumulative pollutant loading rates (see above para-
graph), he or she should document and provide the land
owner or lease holder with the following information:
• Location of land application site.
192
-------
• Date bulk sewage sludge was applied.
• Time bulk sewage sludge was applied if vector at-
traction reduction option 9 or 10 was used.
Number of hectares where the sewage sludge was
applied.
Amount of bulk sewage sludge applied.
B.
C.
Part n-To Be Complete^ fay tAHPAPPLEERS of Sewage Sludge
J
A. If the pollutant levels in the sewage sludge do not meet the pollutant concentration limits in Table 3, then the land applier must
record and retain the following information which should be given to the land owner.
1. Location of land application site.
2. Number of hectares where the sludge was applied.
3. Date and time bulk sewage sludge was applied
4. Amount of bulk sludge applied
5. Record the amount of each metal and nitrogen applied in pounds per acre or kilogram per hectare.
iwt*
Arunle
Ccdmitxft
Ghromtam
Coppn-
Ltui
Mttwty
Molybdenum
Nklttt
Selenium
Zinc
Ntootto
If a Class B pathogen reduction alternative was used (see Part I), then the following site restrictions must be met. Please check the
boxes if any of the site restrictions apply.
1 . Food crops that may touch the sewage sludge/soil mixture cannot be harvested before the end of the following waiting
period:
EH a. If harvested parts are totally above the land, wait to harvest for 14 months after the application of sludge.
EH b. If harvested parts are below the land surface and the sludge sat on top of the soil for 4 months before the field
was plowed, wait to harvest for 20 months after the initial application of sludge.
EH c. If harvested parts are below the land surface and the sludge was incorporated into the soil within 4 months of
being applied, wait to harvest for 38 months after the initial application.
2. EH Feed crops cannot be harvested for 30 days after application of the sludge.
3. EH Animals cannot graze on the land for 30 days after application of the sludge.
4. EH If harvested turf is used for a lawn or other purpose where there is a high potential for public exposure, then the turf
cannot be harvested for 1 year after the application of the sludge to the land.
5. EH Public access to land with
(parks, playgrounds, golf courses) for public exposure will be restricted
for 1 year after the application of the sludge.
6. EH Public access to land with a low potential (private property, remote or restricted public lands) for public exposure
will be restricted for 30 days after the application of the sludge.
If the preparer did not perform vector attraction reduction options (see Part I), then either option 9 or 10 must be performed by the
land applier. Please indicate if option 9 or 10 was performed. Check appropriate box.
Option 9—Subsurface Injection
Option 10—Incorporated (plowed) into the Soil
N/A
D. CERTIFICATION
I certify under penalty of low that this document and all attachments were prepared under my direction or supervision in accordance with a system
designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who
manage the system or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and
belief, true, accurate, and complete. I am aware that mere are significant penalties for submitting false information, including the possibility of fine
and imprisonment for knowing violations.
A. Name and Official Title (type or print)
C. Signature
B. Area Code and Telephone Number
D. Date Signed
Figure 15-7. Notice and necessary information (U.S. EPA, 1993b)
193
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• Cumulative amount of each pollutant (i.e., kilograms)
applied.
The land owner or tenant may request specific informa-
tion, such as analytical results on sludge quality or
documentation on how sludge management practices
are met. In general, the form in Figure 15-7 may be used
to satisfy the notification requirements of both the
preparer and the land applier.
15.6.4.2 Sewage Sludge Sold or Given Away in
a Bag or Other Container for
Application to the Land
When sewage sludge that does not meet the Part 503
pollutant concentration limits is sold or given away in a
bag or other container for application to the land, it must
be accompanied by a label or instruction sheet. The
label or instruction sheet must contain the following
information:
• Name and address of the person who prepared the
sewage sludge.
• Statement that land application is prohibited except
in accordance with the instructions.
• The annual whole sludge application rate that en-
sures that none of the annual pollutant loading rates
in Chapter 3, Table 3-4, are exceeded.
15.6.5 Notice of Interstate Transport
When bulk sewage sludge that does not meet the "ex-
ceptional quality" criteria is going to be applied to land
outside a state in which the sludge was prepared, the
preparer is required to provide written notice to the
permitting authority for the state in which the bulk sew-
age sludge is proposed to be applied, prior to the initial
application of the sewage sludge to a site. The written
notice must include the following information:
• Location, by either street address or latitude and lon-
gitude, of each land application site.
• Approximate time when bulk sewage sludge will be
applied to the site.
• Name, address, telephone number, and National Pol-
lutant Discharge Elimination System (NPDES) permit
number for the person who prepares the bulk sewage
sludge.
• Name, address, telephone number, and NPDES per-
mit number for the person who will apply the bulk
sewage sludge.
15.6.6 Notification by Appliers
The person who applies bulk sewage sludge subject to
the cumulative pollutant loading rates in Part
503.13(b)(2) to the land must provide written notice to
the permitting authority for the state in which the bulk
sewage sludge will be applied, including:
• The location, by either street address or latitude and
longitude, of the land application site.
• The name, address, telephone number, and NPDES
permit number for the person who will apply the bulk
sewage sludge.
15.6.7 Annual Reports
Most preparers are required by Part 503 to report annu-
ally to the permitting authority. Annual reports cover
information and data collected during the calendar year
(January 1 to December 31). Reports on sewage sludge
quality must include the results of monitoring pollutant
concentrations and pathogen levels, a description of
operating parameters for pathogen reduction and vector
attraction reduction, and certifications that pathogen and
vector attraction reductions were achieved. Permits is-
sued by EPA or a state may contain additional reporting
requirements.
15.6.7.1 Persons Responsible for Submitting
Reports Under Part 503
Persons responsible for reporting annually are de-
scribed in the Part 503 regulation as:
• Publicly owned treatment works (POTW) with an av-
erage design influent flow rate equal to or greater
than 1 million gallons per day.
• POTWs serving a population of 10,000 or more.
• Class I sludge management facilities.
Class I sludge management facilities include POTWs
required to have an approved pretreatment program or
that have elected to institute local limits, and treatment
works processing domestic sewage that EPA or the
state have classified as Class I because of the potential
for the use of sewage sludge to negatively affect public
health and the environment. Reports must be submitted
to the permitting authority (either EPA or a state with an
EPA-approved sludge management program).
15.6.7.2 Information Required in Annual Reports
The Part 503 regulation specifies the information
preparers are required to keep in their records. This
includes background information on the generation and
use of sludge; the results of sludge quality analysis; and
a description and certification for pathogen and vector
attraction reduction requirements (see Figure 15-5).
Specific information to be contained in annual reports
include the amount of sewage sludge generated, in
metric tons expressed as a dry weight (see Appendix D
for equations to convert sludge volume to metric tons);
the name and address of the preparer who will receive
194
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the sludge next, if applicable; and the name and address
of the land applier if different from the generator.
The reporting requirements for pollutant limits include
submission of the analytical results from monitoring pol-
lutant concentrations in the sewage sludge. Reports
should include the results of all analyses performed
during the reporting period using the prescribed analyti-
cal method(s) (see Chapter 13). Analytical results must
be reported as milligrams per kilogram (dry weight).
Reports should also indicate which analytical methods
were used, how frequently sludge was monitored, and
the types of samples collected.
Preparers also are required to submit a certification (see
Figure 15-5) and description of how the pathogen reduc-
tion requirements were met. Adetailed description of the
pathogen reduction treatment process should include
the type of process used, standard operating proce-
dures, a schematic diagram, and should identify specific
values for all operating parameters.
Finally, preparers are required to report information regard-
ing vector attraction reduction when one of the sludge
processing options (Option 1-8). The report must contain
a description and certification (see Figure 15-5) that the
vector attraction reduction requirements were met.
The general certification statement that must be used by
preparers and appliers (Figure 15-5) certifies that,
among other things, the preparer or applier and his or
her employees are qualified to gather information and
perform tasks as required by the Part 503 rule. A person
is qualified if he or she has been sufficiently trained. The
certifier should periodically check the performance of his
or her employees to verify that the Part 503 require-
ments are being met. The preparer is required to keep
these records for 5 years for sewage sludge meeting
Part 503 pollutant concentration limits or annual pollut-
ant loading rate limits, and the applier is required to keep
records for the life of the site (indefinitely) for sewage
sludge meeting Part 503 cumulative pollutant loading
rate limits. These required records may be requested for
review at any time by the permitting or enforcement
authority.
15.6.7.3 Submitting Annual Reports
As of 1994, annual reports required under Part 503 are
due February 19 every year. Annual reports must be
submitted to the Permitting Authority, which is the EPA
Regional Water Compliance Branch Chief until state
sludge management programs are delegated the re-
sponsibilities of the federal program.
15.7 References
When an NTIS number is cited in a reference, that
document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
Surge, W. and P. Marsh. 1978. Infections, disease, hazards of land
spreading sewage wastes. Journal of Environmental Quality.
7(1):1-9.
Clark, C. et al. 1980. Occupational hazards associated with sludge
handling. In: Bitton, G. etal., eds. Health risks of land application.
Ann Arbor Science, pp. 215-244.
Elliott et al. 1990. Land application of water treatment plant sludges:
Impact and management. American Water Works Research Foun-
dation, Denver, CO.
Kowal, N. 1983. An overview of public health effects. Presented at
Workshop on the utilization of municipal wastewater and sludge
on land, Denver, CO.
Pahren, H. et al. 1979. Health risks associated with land application
of municipal sludge. Journal of Water Pollution Control Federation,
Vol. 51, pp. 2588-2601.
U.S. EPA. 1994a. A plain English guide to the Part 503 biosolids rule.
EPA/832/R-93/003. Washington, D.C.
U.S. EPA. 1994b. Land application of sewage sludge—A guide for land
appliers on the recordkeeping and reporting requirements of the
federal standards for the use and disposal of sewage sludge man-
agement in 40 CFR Part 503. EPA/831/B-93/002b. Washington, DC.
U.S. EPA. 1993a. Biosolids management handbook for small to me-
dium size POTWs. U.S. EPA Regions 8 and 10. (September 3).
U.S. EPA. 1993b. Preparing sewage sludge for land application or
surface disposal: A guide for preparers of sewage sludge on the
monitoring, record keeping, and reporting requirements of the fed-
eral standards for the use or disposal of sewage sludge, 40 CFR
Part 503. EPA/831/B-93/002a. Washington, DC.
U.S. EPA. 1992. Control of pathogens and vector attraction in sewage
sludge. EPA/625/R-92/013. Washington, DC.
U.S. EPA. 1985. Demonstration of acceptable systems for land dis-
posal of sewage sludge. Cincinnati, OH. EPA/600/2-85/062. (NTIS
PB85-208874).
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Chapter 16
Cost Estimate Guidance for Land Application Systems
16.1 Introduction
This chapter provides information on estimating costs for
sewage sludge land application systems. The cost algo-
rithms presented are taken from ERA'S Handbook: Estimat-
ing Sludge Management Costs (U.S. EPA, 1985) and are
updated using (1994) cost indexes. The costs presented in
this chapter can be updated to later years by the reader
using the appropriate cost indexes (discussed below). The
algorithms cover both capital costs and annual operating
and maintenance (O&M) costs for land application at ag-
ricultural, forest, and land reclamation sites, as well as for
transportation (truck hauling and pipeline transport) of
sewage sludge to land application sites and onsite.
Certain key sludge management costs are not included in
this chapter, such as costs of sludge storage (e.g., la-
goons, tanks, piles) and sludge treatment (e.g., stabiliza-
tion, dewatering, composting). This information must be
added to land application costs if total sludge management
costs are to be accurately represented. The reader should
refer to ERA'S 1985 cost estimation handbook cited above
for sludge treatment and storage cost information.
The cost estimation algorithms present a logical series
of calculations using site-specific, process design, and
cost data for deriving base capital and base annual
operation and maintenance costs. Default values are
provided for many calculations. Most of the algorithms
can be hand-calculated in less than 20 minutes per trial.
Design parameters presented are "typical values" in-
tended to guide the user; the more accurate design
information to which a user has access, the more accu-
rate the resulting costs.
The cost algorithms generally cover a range up to
100 million gallons of sludge per year, which is ap-
proximately equivalent to a wastewater treatment
plant of at least 50 mgd. This range was selected to
include plants where supplemental cost information
might be most useful.
16.1.1 Information Needed Prior to Using
Cost Algorithms
Before using the cost algorithms in this chapter, the
reader must obtain certain data and perform the prelimi-
nary steps described below; otherwise, the resulting
cost estimates may be over- or underestimated.
• Develop a sludge management process chain that
shows the sequence of processes to be used, start-
ing with the raw sludge and ending with final land
application practice.
• Develop a mass balance of sludge volume and
sludge concentration entering and leaving each proc-
ess. This is necessary because many of the cost
algorithms in this chapter require as input data the
volume and the suspended solids content of the
sludge entering the process (which often is not the
raw sludge solids concentration). Thus, an approxi-
mate mass balance must first be computed to obtain
the sludge volume and sludge solids concentration
entering and leaving each process (e.g., treatment).
The volume of raw sludge usually is not the same as the
volume of final treated sludge leaving a treatment proc-
ess, because each successive treatment process gen-
erally tends to reduce the mass and volume of sludge.
Therefore, the mass and volume of the final treated
sludge is typically only a fraction of the initial raw sludge
volume. Similarly, the sludge solids concentration
changes as the sludge proceeds through a series of
treatment processes. The steps involved in performing
a mass balance are described in EPA's 1985 cost hand-
book (U.S. EPA, 1985).
After completing the mass balance procedure, the
reader may use the cost algorithms in this chapter to
estimate the base capital cost and base annual O&M
cost for different land application practices.
16.1.2 Economic Variables
16.1.2.1 Use of Indices for Inflation Adjustment
Numerous estimates of the costs of facility construction,
site preparation, and equipment purchase were devel-
oped by the authors of EPA's 1985 cost handbook (U.S.
EPA, 1985). The base year for these costs, however,
was 1984; hence it is necessary to adjust these esti-
mates to reflect 1994 price levels and costs. For con-
struction-related costs, the standard index used is the
197
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Engineering News Record Construction Cost Index
(ENRCCI). The ratio of the 1994 to 1984 index number
is used here to adjust construction-related cost items.
For equipment purchase costs, the 1984 prices have been
inflated using the Marshall and Swift Equipment Cost In-
dex (MSECI). The ratio of the 1994 to 1984 index number
is used here to adjust equipment-related cost items.
Adjustment for inflation can be made to the following
cost algorithms using:
• The ENRCCI for total base capital costs and total base
annual O&M costs. The ENRCCI appears weekly in
Engineering News Record, published by McGraw Hill,
Inc. (Base 1994 ENRCCI index is 5,445.83.)
• The MSECI to adjust equipment costs or combined
costs in which equipment is the major cost compo-
nent. MSECI is available from Chemical Engineering
magazine. (Base 1994 MSECI index is 990.8.)
16.1.2.2 Labor Rates
The 1985 EPA cost handbook assumed an hourly wage
of $13.00 for operators of heavy equipment which re-
quires considerable skill and training. This rate has been
inflated to 1994 levels using the ENRCCI index, and
adjusted using a factor of 1.3 to account for non-wage
benefits paid by the employer. The effective wage rate,
therefore, is $22.97 per hour.
16.1.2.3 Cost of Diesel Fuel
Diesel fuel costs are assumed to average $1.09 per
gallon, based on average end-user prices for 1994 ob-
tained from the September 12, 1994 edition of Oil and
Gas Journal.
16.1.3 Total Base Capital Cost Estimates
Total base capital costs (TBCC) for sewage sludge land
application systems in this chapter include sludge appli-
cation vehicles, lime addition, grading, brush clearance,
facilities, and acreage required. Costs for engineering
design, construction supervision, legal and administra-
tion expenses, interest during construction, and contin-
gencies are not included. These non-construction costs
must be estimated and added to the process TBCC
costs derived from the cost algorithms to estimate the
total project construction cost.
16.1.4 Total Annual O&M Cost Estimates
The annual O&M costs for sewage sludge land application
in this chapter do not include costs for administration and
laboratory sampling/analysis. These costs must be esti-
mated and added to the process O&M costs derived from
the cost algorithms to obtain the total estimated annual O&M
cost. Total annual O&M costs can be 30 percent higherthan
the costs derived from the algorithms in this chapter.
The total estimated O&M cost calculations in this chapter
also do not include revenues generated through the sale
and/or use of sludge, composting products, or sludge by-
products (i.e., methane produced in anaerobic digestion). If
the user has information available on revenues generated
through usage or sale, O&M costs may be decreased by
subtracting any revenues generated on an annual basis
from the fixed annual O&M cost for that process.
16.1.5 Calculating Cost Per Dry Ton
In sludge processing, it is often desirable to express costs
in terms of annual cost per dry ton. This cost is obtained
by summing the amortized capital cost and base annual
O&M costs and dividing by the annual dry sludge solids
processed (TDSS, as presented in Calculation #1 for ag-
ricultural, forest, and reclamation sites later in this chapter)
and then performing the following calculation:
CPDT = (ACC + COSTOM)/TDSS
where:
CPDT = Cost per dry ton, $/ton.
ACC = Annual amortized capital cost, $/yr
COSTOM = Base annual O&M cost, $/yr.
TDSS = Dry solids applied to land, Tons/yr.
If information on salvage values and revenues gener-
ated from sludge usage is available, it can be subtracted
from the numerator in the above equation.
16.2 Agricultural Land Application
16.2.1 General Information and
Assumptions Made
The cost algorithms for agricultural land application of
sewage sludge presented below assume that the sewage
sludge application vehicles at the application site are not
the same vehicles which transported the sludge from the
treatment plant to the application site. In many cases,
however, the same vehicle is used to both transport sew-
age sludge and apply it to the application site. If the same
vehicle is used for sludge transport and application, then
a zero value should be used for the cost of the onsite
sludge application vehicle (the COSTPV factor) since the
cost of that vehicle has already been included in the
previous sludge hauling process.
The cost algorithms for agricultural land application below
include calculations forthe costs of land, lime addition, and
site grading. At many agricultural land application sites,
however, all or some of these costs are not applicable
to the municipality, since these factors are either unnec-
essary or paid for by the farmer. If the latter applies, a
zero value should be used in the cost algorithms, where
appropriate.
198
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Operation and maintenance (O&M) costs include labor,
diesel for the operation of vehicles, vehicle mainte-
nance, and site maintenance.
If the farm(s) accepting sewage sludge for agricultural
land application are numerous and widespread, an ex-
pensive and complicated sludge distribution system
may be required.
16.2.2 Process Design and Cost Calculations
(1) Calculate dry solids applied to land per year.
TDSS = [(SV)(8.34)(SS)(SSG)(365)]/(2,000)(100)
where:
TDSS
SV
SS
SSG
SSG =
where:
1.42
8.34
2,000
Dry solids applied to land, Tons/yr.
Daily sludge volume, gpd.
Sludge suspended solids concentra-
tion, percent.
Sludge specific gravity, unitless. If
an input value is not available, de-
fault value can be calculated using
the following equation:
- SS)/100) + (SS)/(1.42)(100)]
Assumed sludge solids specific
gravity, unitless.
Density of water, Ib/gal.
Conversion factor, Ib/Ton.
(2) Sludge application area required.
SOAR = (TDSS)/(DSAR)
where:
SOAR
TDSS
DSAR
Farm area required for sludge appli-
cation, ac.
Dry solids applied to land, Tons/yr
(see Calculation #1 above).
Average dry solids application
rate, Tons of dry solids/ac/yr.
This value normally ranges from
3 to 10 for typical food chain crop
growing sites depending on crop
grown, soil conditions, climate,
and other factors. Default value =
5 Tons/ac/yr. (See Chapter 7.)
(3) Hourly sludge application rate.
HSV = (SV)(365)/(DPY)(HPD)
where:
SV = Daily sludge volume, gpd. (See Cal-
culation #1 above.)
DRY = Annual sludge application period,
days/yr. This value normally ranges
from 100 to 140 days/yr depending
on climate, cropping patterns, and
other factors. See Table 16-1 for
typical values. Default value = 120
days/yr.
HPD = Daily sludge application period,
hr/day. This value normally ranges
from 5 to 8 hr/day depending on
equipment used, proximity of appli-
cation sites, and other factors. De-
fault value = 6 hr/day.
Table 16-1. Typical Days Per Year of Food Chain Crop
Sludge Application
Geographic Region
Typical Days/Yr
of Sludge Application
Northern U.S.
Central U.S.
Sunbelt States
100
120
140
(4) Capacity of onsite mobile sludge application vehicles.
It is assumed that the sludge has already been trans-
ported to the private farm land application site by a
process such as a large-haul vehicle, etc. The onsite
mobile application vehicles accept the sludge from the
transport vehicle, pipeline, or onsite storage facility, and
proceed to the sludge application area to apply the
sludge. Typical onsite mobile sludge application vehi-
cles at farm sites have capacities ranging from 1,600 to
4,000 gal, in the following increments: 1,600, 2,200,
3,200, and 4,000 gal.
(4a) Capacity and number of onsite mobile sludge ap-
plication vehicles.
The capacity and number of onsite mobile sludge appli-
cation vehicles required is determined by comparing the
hourly sludge volume, (HSV), with the vehicle sludge
handling rate, (VHRCAP), as shown in Table 16-2.
Above 26,000 gal/hr, the number of 4,000-gal capacity
vehicles required is calculated by:
NOV = HSV/6,545 (round to the next highest integer)
where:
NOV
HSV
HSV
= Hourly sludge application rate, gal/hr.
= Number of onsite sludge application
vehicles.
= Hourly sludge application rate,
gal/hr (see Calculation #3).
199
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Table 16-2. Capacity and Number of Onsite Mobile Sludge
Application Vehicles Required
VHRCAP = [(CAP)(60)(0.9)]/(CT)
Hourly Sludge
Application
Rate (HSV)
HSV (gal/hr)
0-
3,456 -
4,243 -
5,574 -
6,545 -
8,500 -
11,200 -
13,100 -
19,600-
3,456
4,243
5,574
6,545
8,500
11,200
13,100
19,600
26,000
Vehicle Number of Each Capacity (NOV)
Capacity (CAP) (gal)
1,600 2,200 3,200 4,000
1 ...
1
1
1
2
2
2
3
4
(4b) Average round trip onsite cycle time for mobile
sludge application vehicles.
CT = [(LT) + (ULT) + (TT)]/0.75
where:
CT
LT
ULT
0.75
Average round trip onsite cycle
time for mobile sludge application
vehicle, min.
Load time, min, varies with vehicle
size (see Table 16-3).
Unload time, min, varies with vehi-
cle size (see Table 16-3).
Onsite travel time to and from
sludge loading facility to sludge ap-
plication area, min (assumed val-
ues are shown in Table 16-3).
An efficiency factor.
Table 16-3. Vehicle Load, Unload, and Onsite Travel Time
Vehicle
aLT
ULT
TT
CT
Capacity (CAP) LTa
(gal) (min)
1 ,600 6
2,200 7
3,200 8
4,000 9
= Loading time.
= Unloading time.
= Onsite travel time.
= Average round-trip onsite
ULTa
(min)
8
9
10
11
cycle time.
TTa
(min)
5
5
5
5
CTa
(min)
25
28
31
33
(4c) Single vehicle sludge handling rate.
The actual hourly sludge throughput rates for an on-
site mobile sludge application vehicle is dependent on
the vehicle tank capacity, the cycle time, and an effi-
ciency factor.
where:
VHRCAP = Single vehicle sludge handling rate,
gal/hr.
CAP = Vehicle tank capacity, gal.
0.9 = Efficiency factor.
Table 16-4 shows VHRCAP values for typical size vehicles.
Table 16-4. Vehicle Sludge Handling Capacity
Vehicle Capacity (CAP) (gal) VHRCAP3 (gal/hr)
1,600
2,200
3,200
4,000
3,456
4,243
5,574
6,545
VHRCAP = Single vehicle sludge handling rate.
(5) Total land area required.
For virtually all sludge-to-cropland applications, a larger
land area is required than that needed only for sludge
application (SOAR). The additional area may be re-
quired for changes in cropping patterns, buffer zones,
onsite storage, wasted land due to unsuitable soil or
terrain, and/or land available in the event of unforeseen
future circumstances. The additional land area required
is site-specific and varies significantly (e.g., from 10 to
100 percent of the SOAR).
TLAR = (1 + FWWAB)(SDAR)
where:
TLAR = Total land area required for agricul-
tural land application site, ac.
FWWAB = Fraction of farmland area needed in
addition to actual sludge application
area, e.g., buffer zones, unsuitable
soil or terrain, changes in cropping
patterns, etc. Default value = 0.4.
SOAR = Farm area required for sludge appli-
cation, ac (see Calculation #2.)
(6) Lime addition required for soil pH adjustment to a
value of at least 6.5.
TLAPH = (FRPH)(SDAR)
where:
TLAPH = Total land area requiring lime addi-
tion, ac.
FRPH = Fraction of crop growing area re-
quiring lime addition to raise pH
to 6.5. Depending on the natural
200
-------
SOAR
pH of local soils, this fraction can
vary from 0 to 1. Default value = 0.5.
= Farm area required for sludge appli-
cation, ac (see Calculation #2.)
Table 16-5. Gallons of Fuel Per Hour for Various Capacity
Sludge Application Vehicles
(7) Total land area requiring light grading.
Typical agricultural land used for growing crops is usually
already graded to even slopes. However, when sewage
sludge is added to the soil, additional light grading may be
necessary to improve drainage control and minimize runoff
of sludge solids. This need is site-specific.
TLARLG = (FRLG)(SDAR)
where:
TLARLG
FRLG
SOAR
Total land area requiring light grad-
ing, ac.
Fraction of crop-growing area requir-
ing light grading for drainage con-
trol. Depending on local conditions
at the sludge application sites this
fraction can vary from 0 to 1. De-
fault value = 0.3.
Farm area required for sludge appli-
cation, ac (see Calculation #2.)
(8) Annual operation labor requirement.
L = 8 (NOV)(DPY)/0.7
where:
L
NOV
DRY
8
0.7
Annual operation labor require-
ment, hr/yr.
Number of onsite sludge application
vehicles (see Calculation #4).
Annual sludge application period,
days/yr (see Calculation #3).
Hr/day assumed.
Efficiency factor.
(9) Annual diesel fuel requirement for onsite mobile
sludge application vehicles.
FU = (HSV)(HPD)(DPY)(DFRCAP)/(VHRCAP)
where:
FU
HSV
HPD
DPY
DFRCAP =
VHRCAP =
Annual diesel fuel usage, gal/yr.
Hourly sludge application rate,
gal/hr (see Calculation #3).
Daily sludge application period,
hr/day (see Calculation #3).
Annual sludge application period,
days/yr (see Calculation #3).
Diesel fuel consumption rate
(gal/hr); for specific capacity vehi-
cle, see Table 16-5.
Vehicle sludge handling rate (see
Calculation #4).
Vehicle Capacity (CAP) (gal)
DFRCAP3 (gal/hr)
1,600
2,200
3,200
4,000
3.5
4
5
6
' DFRCAP = Diesel fuel consumption rate.
(10) Cost of land.
COSTLAND = (TLAR)(LANDCST)
where:
COSTLAND=
TLAR
LANDCST =
Cost of land, $.
Total land area required for agricul-
tural land application site, ac (see
Calculation #5).
Cost of land, $/ac. Default value =
0. It is assumed that application
of sludge is to privately owned
farm land.
(11) Cost of lime addition to adjust pH of soil.
COSTPHT = (TLAPH)(PHCST)
where:
COSTPHT =
TLAPH
PHCST
Cost of lime addition, $.
Total land area requiring lime addi-
tion, ac (see Calculation #6)
Cost of lime addition, $/ac. Default
value = $82/acre (ENRCCI/5,445.83);
assumes 2 Tons of lime/ac requirement.
(12) Cost of light grading earthwork.
COSTEW = (TLARLG)(LGEWCST)
where:
COSTEW = Cost of earthwork grading, $.
TLARLG = Total land area requiring light grad-
ing, ac (see Calculation #7)
LGEWCST= Cost of light grading earthwork,
$/ac. Default value = $1,359/ac.
(ENRCCI/5,445.83).
(13) Cost of onsite mobile sludge application vehicles.
Note: If same vehicle is used both to transport sludge to the
site and to apply sludge to the land, then COSTMAV = 0.
COSTMAV = (NOV)(COSTPV)
MSECI
990.8
where:
COSTMAV = Cost of onsite mobile sludge appli-
cation vehicles, $.
201
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NOV = Number of onsite sludge application
vehicles (see Calculation #4).
COSTPV = Cost of onsite mobile sludge ap-
plication vehicle, obtained from
Table 16-6.
MSECI = Current Marshall and Swift Equip-
ment Cost Index at time analysis is
made.
Table 16-6. Cost of Onsite Mobile Sludge Application
Vehicles
Vehicle Capacity (CAP) (gal)
Cost Per Vehicle
(COSTPV) (1994 $)a
1,600
2,200
3,200
4,000
112,000
125,000
158,000
185,000
Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(14) Annual cost of operation labor.
COSTLB = (L)(COSTL)
where:
COSTLB
L
COSTL
Annual cost of operation labor, $/yr.
Annual operation labor required, hr/yr.
Cost of operation labor, $/hr. De-
fault value = $22.97/hr.
(ENRCCI/5,445.83).
(15) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL =
FU
COSTDF =
Annual cost of diesel fuel, $/yr.
Annual diesel fuel usage, gal/yr.
Cost of diesel fuel, $/gal. Default
value = $1.09/gal.
(ENRCCI/5,445.83).
(16) Annual cost of maintenance for onsite mobile
sludge application vehicles.
VMC =
[(HSV)(HPD)(DPY)(MCSTCAP)/(VHRCAP)]
MSECI
990.8
where:
VMC
HSV
HPD
Annual cost of vehicle mainte-
nance, $/yr.
Hourly sludge application rate,
gal/hr (see Calculation #3).
Daily sludge application period,
hr/day (see Calculation #3).
DPY = Annual sludge application period,
days/yr (see Calculation #3).
MCSTCAP = Maintenance cost, $/hr of opera-
tion; for specific capacity of vehicle,
see Table 16-7.
VHRCAP = Vehicle sludge handling rate (see
Calculation #4).
MSECI = Current Marshall and Swift Equipment
Cost Index at time analysis is made.
Table 16-7. Hourly Maintenance Cost for Various Capacities
of Sludge Application Vehicles
Vehicle Capacity (CAP)
(gal)
Maintenance Cost (MCSTCAP)
($/hr, 1994 $)a
1,600
2,200
3,200
4,000
6.40
7.01
7.86
9.45
Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(17) Annual cost of maintenance for land application site
(other than vehicles) including monitoring, recordkeep-
ing, etc.
SMC = [(TLAR)(16)]
ENRCCI
5,445.83
where:
SMC
TLAR
16
ENRCCI
Annual cost of maintenance (other
than vehicles), $/yr.
Total land area required for land
application site, ac (see Calculation
#5).
Annual maintenance cost, $/ac.
Current Engineering News Record
Construction Cost Index at time
analysis is made.
(18) Total base capital cost.
TBCC = COSTLAND + COSTPHT + COSTEW
+ COSTMAV
where:
TBCC = Total base capital cost of agricul-
tural land application program using
onsite mobile sludge application
vehicles, $.
COSTLAND = Cost of land for sludge application
site, $ (see Calculation #10).
COSTPHT = Cost of lime addition, $ (see Calcu-
lation #11).
COSTEW = Cost of light grading earthwork, $
(see Calculation #12) .
COSTMAV = Cost of onsite mobile sludge applica-
tion vehicles, $ (see Calculation #13).
202
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(19) Total annual operation and maintenance cost.
COSTOM = COSTLB + COSTDSL + VMC + SMC
where:
COSTOM
COSTLB
COSTDSL
VMC
SMC
Total annual operation and mainte-
nance cost for agricultural land ap-
plication program using onsite mobile
sludge application vehicles, $/yr.
Annual cost of operation labor, $/yr
(see Calculation #14).
Annual cost of diesel fuel, $/yr (see
Calculation #15).
Annual cost of vehicle mainte-
nance, $/yr (see Calculation #16).
Annual cost of site maintenance,
$/yr (see Calculation #17).
16.3 Application to Forest Lands
16.3.1 General Information and
Assumptions Made
The cost algorithms presented below for forest land
application estimate only the cost of sewage sludge
application at the forest site using specially designed
onsite liquid sludge application vehicles. It is assumed
that the sludge is transported to the site by one of the
transportation processes discussed in Section 16.5.
Typically, the onsite liquid sludge application vehicles will
obtain sludge from a large "nurse" truck, or an on-site
sludge storage facility. These cost algorithms assume
that liquid sludge is applied by means of specially de-
signed tanker trucks equipped with a spray "cannon"
having a range of approximately 100 ft.
Unlike agricultural land application which usually in-
volves annual sewage sludge application, forest land
application to a specific site is often done at multi-year
intervals, e.g., every 5 years, which will influence costs.
In addition, forest land sites are usually less accessible
to sludge application vehicles than cropland, and on-site
clearing and grading of access roads is often an initial
capital cost. Provisions for estimating the cost of clear-
ing brush and trees and grading rough access roads,
which are often paid by the land owner, are included in
these cost algorithms.
While provision is made in the cost algorithms for in-
cluding land costs, the municipality generally will not
purchase or lease the application site, and land cost will
be zero.
Base capital costs include (where appropriate) the cost
of land, clearing brush and trees, grading, and mobile
sludge application vehicles. Base annual O&M costs
include labor, diesel fuel for vehicles, vehicle mainte-
nance, and site maintenance.
16.3.2 Process Design and Cost Calculations
(1) Calculate dry solids applied to land per year.
TDSS = [(SV)(8.34)(SS)(SSG)(365)]/(2,000)(100)
Same as Calculation #1 for agricultural land application
(see Section 16.2 above).
(2) Sludge application area required.
SOAR = (TDSS)(FR)/(DSAR)
where:
SOAR
TDSS
FR
= Site area required for sludge appli-
cation, ac.
= Dry solids applied to land, Tons/yr
(from Calculation #1).
= Frequency of sludge application to for-
est land at dry solids application rate
(DSAR) (i.e., period between applica-
tion of sludge to some forest land
area), yr. This value varies depending
on tree species, tree maturity, whether
trees are grown for commercial pur-
poses, and other factors. Default
value = 5 yr.
DSAR = Average dry solids application rate,
Tons of dry solids/ac. This value nor-
mally ranges from 20 to 40 for typical
forest land sites depending on tree
species, tree maturity, soil conditions,
and other factors. Default value = 20
Tons/ac/yr. (See Chapter 8.)
(3) Hourly sludge volume which must be applied.
HSV = (SV)(365)/(DPY)(HPD)
where:
HSV
SV
DPY
= Hourly sludge volume during appli-
cation period, gal/hr.
= Daily sludge volume, gpd. (See Cal-
culation #1.)
= Annual sludge application period,
days/yr. This value normally ranges
from 130 to 180 days/yr for forest
land sites depending on climate,
soil conditions, and other factors.
Default value = 150 days/yr.
HPD = Daily sludge application period,
hr/day. This value normally ranges
from 5 to 8 hr/day depending on
equipment used, site size, and other
factors. Default value = 7 hr/day.
(4) Capacity of onsite mobile sludge application vehicles.
It is assumed that the sludge has already been trans-
ported to the forest land application site by a transport
203
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process such as truck hauling. The onsite mobile ap-
plication vehicles accept the sludge from a large nurse
truck, on-site storage facility, etc., and proceed to the
sludge application area to apply the sludge. Typical
onsite mobile sludge application vehicles at forest
land sites are specially modified tank trucks equipped
with a sludge cannon to spray the sludge at least 100
ft through a 240-degree horizontal arc. The applica-
tion vehicle is modified to handle steep slopes, sharp
turn radius, and doze through small trees and brush.
Such vehicles can negotiate much rougher terrain,
e.g., logging roads, than conventional road tanker
trucks. Because of the special conditions encountered
in forest land sludge application, it is assumed that the
largest onsite sludge application vehicle feasible has
a capacity of 2,200 gal of sludge. Only two capacity
increments are included in this program, i.e., 1,000
gal and 2,200 gal.
(4a) Capacity and number of onsite mobile sludge ap-
plication vehicles.
The capacity and number of onsite mobile sludge appli-
cation vehicles required is determined by comparing the
hourly sludge volume, HSV, with the vehicle sludge
handling rate, VHRCAP, as shown in Table 16-8.
Above 7,584 gal/hr, the number of 2,200-gal capacity
vehicles required is calculated by:
NOV = HSV/2,528 (round to the next highest integer)
where:
NOV
HSV
Number of onsite mobile sludge ap-
plication vehicles.
Hourly sludge volume during appli-
cation period, gal/hr (see Calcula-
tion #3).
Table 16-8. Capacity and Number of Onsite Mobile Sludge
Application Vehicles Required
Vehicle Number of Each Capacity
(NOV) Capacity (CAP) (gal)
HSVa (gal/hr)
0 - 1,317
1,317 - 2,528
2,528 - 5,056
5,056 - 7,584
1,000 2,200
1
1
2
3
Hourly sludge volume during application period.
(4b) Average round trip on-site cycle time for mobile
sludge application vehicles.
CT = [(LT) + (ULT) + (TT)]/0.75
where:
CT
LT
ULT
0.75
Average round trip on-site cycle
time for mobile sludge application
vehicle, min.
Load time, min, varies with vehicle
size (see Table 16-9).
Unload time, min, varies with vehi-
cle size (see Table 16-9).
On-site travel time to and from
sludge loading facility to sludge ap-
plication area, min (assumed val-
ues are shown in Table 16-9).
An efficiency factor.
(4c) Single vehicle sludge handling rate.
Table 16-9. Vehicle Load, Unload, and Onsite Travel Time3
Vehicle Capacity, LT ULT TT
CAP (gal) (min) (min) (min)
al_T
ULT
TT
CT
1,000
2,200
=
6810
7 9 10
Loading time.
Unloading time.
Onsite travel time.
Average round-trip onsite cycle time.
CT
(min)
32
35
The actual hourly sludge throughput rates for an onsite
mobile sludge application vehicle is dependent on the
vehicle tank capacity, the cycle time, and an efficiency
factor.
VHRCAP = [(CAP)(60)(0.9)]/(CT)
where:
VHRCAP
CAP
0.9
Single vehicle sludge handling rate,
gal/hr.
Capacity of onsite mobile sludge ap-
plication vehicle, gal.
Efficiency factor.
Table 16-10 shows VHRCAP values for typical size
vehicles.
Table 16-10. Vehicle Sludge Handling Capacity
Vehicle Capacity, (CAP) (gal) VHRCAP3 (gal/hr)
1,000
2,200
1,317
2,528
VHRCAP = Single vehicle sludge handling rate.
204
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(5) Total land area required.
For virtually all forest land sites, a larger land area
is required than that needed only for sludge appli-
cation (SOAR). The additional area may be required
for buffer zones, on-site roads, on-site storage,
wasted land due to unsuitable soil or terrain, etc.
The additional land area required is site-specific
and varies significantly, e.g., from 10 to 50 percent
of the SOAR.
TLAR = (1 + FWWAB)(SDAR)
where:
TLAR
FWWAB =
SOAR
Total land area required for forest
land site, ac.
Fraction of forest land site area
used for purposes other than
sludge application, e.g., buffer
zone, internal roads, sludge stor-
age, waste land, etc. Varies signifi-
cantly depending on site-specific
conditions. Default value = 0.2 for
forest land sites.
Site area required for sludge appli-
cation, ac (see Calculation #2).
(6) Clearing of brush and trees required.
Often a forest land site will require clearing brush and
trees in access road areas to allow access by the sludge
application vehicle.
TLAWB = (FWB)(TLAR)
where:
TLAWB
FWB
TLAR
Total land area with brush and
trees to be cleared, ac.
Fraction of forest land site area re-
quiring clearing of brush and trees
to allow access by application vehi-
cle. Varies significantly depending
on site-specific conditions. Default
value = 0.05 for forest land sites.
Total land area required for forest
land site, ac (see Calculation #5).
(7) Earthwork required.
Often a forest land application site will require grading
of access roads for the sludge application vehicles, to
provide drainage control, etc. The extent of grading
required is site-specific.
TLARG = (FRG)(TLAR)
where:
TLARG
FRG
TLAR
Total land area requiring grading, ac.
Fraction of land area requiring
grading of access roads to allow
travel by sludge application vehi-
cle, etc. Varies significantly de-
pending on site-specific
conditions. Default value = 0.05
for forest land sites.
Total land area required for forest
land site, ac (see Calculation #5).
(8) Annual operation labor requirement.
L = 8 (NOV)(DPY)/0.7
where:
L
8
NOV
DRY
0.7
Annual operation labor requirement,
hr/yr.
Hr/day assumed.
Number of onsite sludge application
vehicles (see Calculation #4).
Annual sludge application period,
days/yr (see Calculation #3).
Efficiency factor.
(9) Annual diesel fuel requirement for onsite mobile
sludge application vehicles.
FU = (HSV)(HPD)(DPY)(DFRCAP)/(VHRCAP)
where:
FU
HSV
= Annual diesel fuel usage, gal/yr.
= Hourly sludge application rate,
gal/hr (see Calculation #3).
HPD = Daily sludge application period,
hr/day (see Calculation #3).
DPY = Annual sludge application period,
days/yr (see Calculation #3 above).
DFRCAP = Diesel fuel consumption rate
(gal/hr); for specific capacity vehicle
(see Table 16-11).
VHRCAP = Vehicle sludge handling rate (see
Calculation #4).
Table 16-11. Gallons of Fuel Per Hour for Various Capacity
Sludge Application Vehicles
Vehicle Capacity, (CAP) (gal)
DFRCAP3 (gal/hr)
1,000
2,200
DFRCAP = Diesel fuel consumption rate.
205
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(10) Cost of land for forest land application site.
COSTLAND = (TLAR)(LANDCST)
where:
COSTLAND =
TLAR
LANDCST =
Cost of land for forest land site, $.
Total land area required for forest
land site, ac. (see Calculation #5)
Cost of land, $/ac. Usually the for-
est land is not purchased by the
municipality. Default value = 0.
(11) Cost of clearing brush and trees.
COSTCBT = (TLAWB)(BCLRCST)
where:
COSTCBT =
TLAWB =
BCLRCST =
Cost of clearing brush and trees, $.
Total land area with brush and
trees to be cleared, ac (see Calcula-
tion #6).
Cost of clearing brush and trees,
$/ac. Default value = $1,359/acre
(ENRCCI/5,445.83).
(12) Cost of grading earthwork.
COSTEW = (TLARG)(GEWCST)
where:
COSTEW
TLARG
Cost of earthwork grading, $.
Total land area requiring grading,
ac (see Calculation #7).
GEWCST = Cost of grading earthwork, $/ac. De-
fault value = $2,039/acre
(ENRCCI/5,445.83).
(13) Cost of onsite mobile sludge application vehicles.
MSECI
COSTMAV = [(NOV)(COSTPV)]
990.8
where:
COSTMAV=
NOV
COSTPV =
MSECI
Cost of onsite mobile sludge appli-
cation vehicles, $.
Number of onsite sludge application
vehicles (see Calculation #4).
Cost/vehicle, obtained from Table
16-12.
Current Marshall and Swift Equip-
ment Cost Index at time analysis is
made.
Table 16-12. Cost of On-Site Mobile Sludge Application
Vehicles (1994)
Vehicle Capacity, (CAP) (gal)
COSTPV (1994 $)a
1,000
2,200
158,000
198,000
Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(14 ) Annual cost of operation labor.
COSTLB = (L)(COSTL)
where:
COSTLB = Annual cost of operation labor, $/yr.
L = Annual operation labor requirement,
hr/yr (see Calculation #8).
COSTL = Cost of operational labor, $/hr. De-
fault value = $22.97/hr
(ENRCCI/5,445.83).
(15) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL =
FU
Annual cost of diesel fuel, $/yr.
Annual diesel fuel usage, gal/yr
(see Calculation #9).
COSTDF = Cost of diesel fuel, $/gal. Default
value = $1.09/gal (ENRCCI/5,445.83).
(16) Annual cost of maintenance of onsite mobile sludge
application vehicles.
VMC =
[(HSV)(HPD)(DPY)(MCSTCAP)/(VHRCAP)]
MSECI
990.8
where:
VMC
HSV
HPD
DPY
MCSTCAP =
MSECI
Annual cost of vehicle mainte-
nance, $/yr.
Hourly sludge application rate,
gal/hr (see Calculation #3).
Daily sludge application period,
hr/day (see Calculation #3).
Annual sludge application period,
days/yr (see Calculation #3).
Maintenance cost, $/hr of operation
for specific capacity of vehicle; see
Table 16-13.
Current Marshall and Swift Equip-
ment Cost Index at time analysis is
made.
206
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Table 16-13. Hourly Maintenance Cost for Various Capacities
of Forest Land Sludge Application Vehicles
Vehicle Capacity, (CAP) (gal)
MSCTCAP3 ($/hr, 1994)b
1,000
2,200
8.05
9.63
MSCTCAP = Maintenance cost.
' Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(17) Annual cost of maintenance for forest land site
(other than vehicles) including monitoring, record-
keeping, etc.
SMC = [(TLAR)(16)]
where:
SMC
ENRCCI
5,445.83
= Annual cost of forest land site main-
tenance (other than vehicles), $/yr.
TLAR = Total land area required for forest
land site, ac (see Calculation #5).
16 = Annual maintenance cost, $/ac.
ENRCCI = Current Engineering News Record
Construction Cost Index at time
analysis is made.
(18) Total base capital cost.
TBCC = COSTLAND + COSTCBT + COSTEW +
COSTMAV
where:
TBCC
COSTLAND =
COSTCBT =
COSTEW =
COSTMAV=
Total base capital cost of forest land
application site using onsite mobile
sludge application vehicles, $.
Cost of land for forest land site, $
(see Calculation #10).
Cost of clearing brush and trees, $
(see Calculation #11).
Cost of earthwork grading, $ (see
Calculation #12).
Cost of onsite mobile sludge applica-
tion vehicles, $ (see Calculation #13).
(19) Total annual operation and maintenance cost.
COSTOM = COSTLB + COSTDSL + VMC + SMC
where:
COSTOM =
COSTLB =
COSTDSL =
VMC
Total annual operation and mainte-
nance cost for forest land applica-
tion site using onsite mobile sludge
application vehicles, $/yr.
Annual cost of operation labor, $/yr
(see Calculation #14).
Annual cost of diesel fuel, $/yr (see
Calculation #15).
Annual cost of vehicle mainte-
nance, $/yr (see Calculation #16).
SMC = Annual cost of forest land site main-
tenance (other than vehicles), $/yr
(see Calculation #17).
16.4 Land Application at Reclamation Sites
16.4.1 General Information and
Assumptions Made
The cost algorithms for land application of sewage
sludge at reclamation sites presented below do not
generate the total land area required, as do the other
land application cost algorithms in this chapter, but in-
stead generate the annual land area required. This is
because sewage sludge application for land reclamation
is usually a one-time application (i.e., sewage sludge is
not applied again to the same land area at periodic
intervals in the future), and the project must therefore
have a continuous supply of new disturbed land on
which to apply sewage sludge in future years throughout
the life of the sludge application project.
The cost algorithms presented for land application at
reclamation sites estimate only the cost of sewage
sludge application at the site using onsite sludge appli-
cation vehicles. It is assumed that the sewage sludge
is transported to the site by one of the transportation
processes discussed in Section 16.5. Typically, the on-
site sludge application vehicles will obtain sludge from
a large "nurse" truck, or an interim on-site sludge stor-
age facility. However, if the same truck is used to both
haul and apply the sludge, do not add the cost of onsite
application trucks (i.e., COSTMAV in the algorithms
would equal zero).
Disturbed or marginal lands often require extensive
grading, soil pH adjustment by lime addition, scarifying,
and vegetation seeding. Usually, the landowner pays for
the cost of these operations. However, there are provi-
sions for including these costs in the cost algorithms, if
desired.
16.4.2 Process Design and Cost Calculations
(1) Calculate dry solids applied to land per year.
TDSS = [(SV)(8.34)(SS)(SSG)(365)]/(2,000)(100)
Same as Calculation #1 for agricultural land application
(see Section 16.2).
(2) Sludge application area required.
SOAR = (TDSS)/(DSAR)
where:
SOAR
= Land area required for sludge applica-
tion, ac/yr. Since sludge is typically
applied only once to reclamation
207
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sites, the sludge application area re-
quired represents the annual new
land area which must be located
each year.
TDSS = Dry solids applied to land, Tons/yr
(see Calculation #1).
DSAR = Average dry solids application rate,
Tons of dry solids/ac/yr. This value
normally ranges from 10 to 100 for
typical land reclamation sites depend-
ing on sludge quality, soil conditions,
and other factors. Default value = 25
Tons/ac. (See Chapter 9.)
(3) Hourly sludge application rate.
HSV = (SV)(365)/(DPY)(HPD)
where:
HSV
SV
DRY
= Hourly sludge application rate, gal/hr.
= Daily sludge volume, gpd. (See Cal-
culation #1.)
= Annual sludge application period,
days/yr. This value normally ranges
from 100 to 180 days/yr for land
reclamation sites depending on cli-
mate, soil conditions, planting sea-
sons, and other factors. Default
value = 140 days/yr.
HPD = Daily sludge application period,
hr/day. This value normally ranges
from 5 to 8 hr/day depending on
equipment used, site size, and other
factors. Default value = 8 hr/day.
(4) Capacity of onsite mobile sludge application vehicles.
Same as Calculations #4a, b, and c in Section 16.2.2 for
agricultural land application sites.
(5) Total land area required per year.
For virtually all land reclamation sites, a larger land area is
required than that needed only for sludge application
(SOAR). The additional area may be required for buffer
zones, on-site roads, on-site storage, wasted land due to
unsuitable terrain, etc. The additional land area required
for land reclamation sites is usually not significant, since
these sites are typically located far from population centers.
TLAR = (1 + FWWAB)(SDAR)
where:
TLAR
FWWAB =
Total land area required for land rec-
lamation sites, ac/yr.
Fraction of land reclamation site
area used for purposes other than
sludge application, e.g., buffer zone,
internal roads, sludge storage, waste
SOAR
land, etc. Varies significantly de-
pending on site-specific conditions.
Default value = 0.3 for land recla-
mation sites.
Site area required for sludge appli-
cation, ac/yr (see Calculation #2).
(6) Lime addition required for soil pH adjustment to a
value of pH = 6.5.
TLAPH = (FRPH)(SDAR)
where:
TLAPH
FRPH
SOAR
Total land area which must have
lime applied for pH control, ac/yr.
Fraction of land reclamation site area
requiring addition of lime for adjust-
ment of soil pH to a value of 6.5.
Typically, strip mining spoils have a
low soil pH, and substantial lime addi-
tion may be required. Default value =
1.0 for land reclamation sites.
Site area required for sludge appli-
cation, ac/yr (see Calculation #2).
(7) Earthwork required.
Usually a potential land reclamation site will require
extensive grading to smooth out contours, provide drain-
age control, etc. The extent of grading required is very
site-specific, and can represent a significant portion of
the total site preparation cost when the terrain is rough.
TLARLG = (FRLG)(TLAR)
TLARMG = (FRMG)(TLAR)
TLAREG = (FREG)(TLAR)
where:
TLARLG = Total land area requiring light grad-
ing, ac/yr.
TLARMG = Total land area requiring medium
grading, ac/yr.
TLAREG = Total land area requiring extensive
grading, ac/yr.
FRLG = Fraction of land area requiring light
grading. Varies significantly depend-
ing on site-specific conditions. De-
fault value = 0.1.
FRMG = Fraction of land area requiring me-
dium grading. Varies significantly de-
pending on site-specific conditions.
Default value = 0.3.
FREG = Fraction of land area requiring ex-
tensive grading. Varies significantly
depending on site-specific condi-
tions. Typically, a land reclamation
site requires significant heavy grad-
ing. Default value = 0.6.
208
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TLAR = Total land area required per year
(TLAR) (see Calculation #5).
(8) Possible number of monitoring wells needed.
Many state regulatory agencies require that ground-water
quality monitoring wells be installed as a condition of land
reclamation site permitting. The permitting authority may
also require ground-water monitoring if he or she has
approved land application in excess of agronomic rates at
a reclamation site, as allowed by the federal Part 503
regulation. The number and depth of monitoring wells re-
quired varies as a function of site size, ground-water condi-
tions, and regulatory agency requirements. In this
algorithm, it is assumed that even the smallest land recla-
mation site must have one downgradient ground-water
quality monitoring well, and one additional monitoring well
for each 200 ac/yr of total site area (TLAR) above 50 ac/yr.
In some cases, at least one upgradient well is also re-
quired.
NOMWR = 1 + [(TLAR) - 50]/200 (increase to
next highest integer)
where:
NOMWR = Number of monitoring wells re-
quired/yr.
TLAR = Total land area required per year
(see Calculation #5).
(9) Operation labor requirement.
L = 8 (NOV)(DPY)/0.7
where:
L
8
NOV
DPY
0.7
= Operation labor requirement, hr/yr.
= Hr/day assumed, hr.
= Number of onsite sludge application
vehicles (see Calculation #4).
= Annual sludge application period,
days/yr (see Calculation #3).
= Efficiency factor.
(10) Diesel fuel requirements for onsite mobile sludge
application vehicles.
FU = (HSV)(HPD)(DPY)(DFRCAP)/(VHRCAP)
where:
FU
HSV
HPD
DPY
DFRCAP
Diesel fuel usage, gal/yr.
Hourly sludge application rate,
gal/hr (see Calculation #3).
Daily sludge application period,
hr/day (see Calculation #3).
Annual sludge application period,
days/yr (see Calculation #3).
Diesel fuel consumption rate for certain
capacity vehicle, gal/hr, see Table 16-5.
VHRCAP = Vehicle sludge handling rate (see
Calculation #4).
(11) Annual cost of land.
COSTLAND = (TLAR) (LAN DCST)
where:
COSTLAND =
TLAR
LANDCST =
Annual cost of land for land recla-
mation site, $/yr.
Total land area required for land
reclamation sites, ac/yr (see Calcu-
lation #5).
Cost of land, $/ac. Typically, the
land used for reclamation is not pur-
chased by the municipality. Default
value = 0.
(12) Annual cost of lime addition to adjust pH of the soil.
COSTPHT = (TLAPH)(PHCST)
where:
COSTPHT = Annual cost of lime addition for pH
adjustment, $/yr.
TLAPH = Total land area which must have
lime applied for pH control, ac/yr
(see Calculation #6).
PHCST = Cost of lime addition, $/ac. Default
value = $163/ac.
(ENRCCI/5,445.83), based on 4
Tons of lime/ac (in some cases up
to 10 Tons/ac may be required for
extreme pH conditions).
(13) Annual cost of grading earthwork.
COSTEW = (TLARLG)(LGEWCST) + (TLARMG)
(MGEWCST) + (TLAREG)(EGEWCST)
where:
COSTEW = Cost of earthwork grading, $/yr.
TLARLG = Total land area requiring light grad-
ing, ac/yr (see Calculation #7).
LGEWCST= Cost of light grading earthwork,
$/ac. Default value = $1,359/ac.
(ENRCCI/5,445.83).
TLARMG = Total land area requiring medium
grading, ac/yr (see Calculation #7).
MGEWCST= Cost of medium grading earthwork,
$/ac. Default value = $2,719/ac.
(ENRCCI/5,445.83).
TLAREG = Total land area requiring extensive
grading, ac/yr (see Calculation
#7).
EGEWCST= Cost of extensive grading earth-
work, $/ac. Default value =
$6,797/ac. (ENRCCI/5,445.83).
209
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(14) Annual cost of monitoring wells.
COSTMW = ( NOMWR)(MWCST)
where:
COSTMW =
NOMWR =
MWCST =
Cost of monitoring wells, $/yr.
Number of monitoring wells re-
quired/yr (see Calculation #8).
Cost of monitoring well, $/well. De-
fault value = $6,797/well
(ENRCCI/5,445.83).
(15) Cost of onsite mobile sludge application vehicles.
MSECI
COSTMAV = [(NOV)(COSTPV)]
990.8
where:
COSTMAV=
NOV
COSTPV =
MSECI
Cost of onsite mobile sludge appli-
cation vehicles, $.
Number of onsite sludge application
vehicles (see Calculation #4).
Cost/vehicle, $, obtained from
Table 16-6.
Current Marshall and Swift Equip-
ment Cost Index at time analysis
is made.
(16) Annual cost of operation labor.
COSTLB = (L)(COSTL)
where:
COSTLB
L
COSTL
Annual cost of operation labor, $/yr.
Annual operation labor required, hr/yr.
Cost of operational labor, $/hr. De-
fault value = $22.97/hr.
(ENRCCI/5,445.83).
(17) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL = Annual cost of diesel fuel, $/yr.
FU = Annual diesel fuel usage, gal/yr.
COSTDF = Cost of diesel fuel, $/gal. Default
value = $1.09/gal
(ENRCCI/5,445.83).
(18) Annual cost of maintenance of onsite mobile sludge
application vehicles.
VMC =
[(HSV)(HPD)(DPY)(MCSTCAP)/(VHRCAP)]
MSECI
990.8
where:
VMC
= Annual cost of vehicle mainte-
nance, $/yr.
HSV = Hourly sludge application rate,
gal/hr (see Calculation #3).
HPD = Daily sludge application period,
hr/day (see Calculation #3).
DPY = Annual sludge application period,
days/yr (see Calculation #3).
MCSTCAP = Maintenance cost, $/hr of opera-
tion; for specific capacity of vehicle
see Table 16-7.
VHRCAP = Vehicle sludge handling rate (see
Calculation #4)
MSECI = Current Marshall and Swift Equipment
Cost Index at time analysis is made.
(19) Annual cost of maintenance of land reclamation site
(other than vehicles) for monitoring, recordkeeping, etc.
SMC = [(TLAR)(16)]
ENRCCI
5,445.83
where:
SMC
TLAR
16
ENRCCI
Annual cost of land reclamation site
maintenance (other than vehicles), $/yr.
Total land area required, ac (see
Calculation #5).
Annual maintenance cost, $/ac.
Current Engineering News Record
Construction Cost Index at time
analysis is made.
(20) Total base capital cost.
TBCC = COSTMAV
where:
TBCC = Total base capital cost of land recla-
mation site using onsite mobile
sludge application vehicles, $.
COSTMAV = Cost of onsite mobile sludge applica-
tion vehicles, $ (see Calculation #15).
(21) Total annual operation, maintenance, land, and
earthwork cost.
COSTOM = COSTLB + COSTDSL + VMC + SMC +
COSTLAND + COSTPHT + COSTEW + COSTMW
where:
COSTOM =
COSTLB =
COSTDSL =
VMC
Total annual operation, mainte-
nance, land, and earthwork cost for
land reclamation site using onsite mo-
bile sludge application vehicles, $/yr.
Annual cost of operation labor, $/yr
(see Calculation #16).
Annual cost of diesel fuel, $/yr (see
Calculation #17).
Annual cost of vehicle mainte-
nance, $/yr (see Calculation #18).
210
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SMC = Annual cost of site maintenance,
$/yr (see Calculation #19).
COSTLAND = Annual cost of land for reclamation
site, $/yr (see Calculation #11).
COSTPHT = Annual cost of lime addition for pH
adjustment,$/yr (see Calculation #12).
COSTEW = Annual cost of grading earthwork,
$/yr (see Calculation #13).
COSTMW = Annual cost of monitoring wells,
$/yr (see Calculation #14).
16.5 Transportation of Sewage Sludge
This section covers the two primary modes of sewage
sludge transport, truck hauling (for both liquid and de-
watered sludge) and pipeline transport of liquid sludge.
For cost estimate information regarding rail or barge
transport of sewage sludge, see EPAs Handbook: Esti-
mating Sludge Management Costs (U.S. EPA, 1985).
Generally, truck hauling is more economical than rail-
road or pipeline when transporting sewage sludge less
than 150 miles. Diesel-equipped vehicles are an eco-
nomic choice for larger trucks and trucks with high an-
nual mileage operation. Pipelines have been successfully
used for transporting liquid sludge (i.e., usually less than
10 percent solids by weight) from very short distances
up to distances of 10 miles or more. Liquid sludge
pumping through pipelines is generally best accom-
plished with sludge containing 3 percent solids or less.
16.5.1 Truck Hauling of Liquid Sewage Sludge
16.5.1.1 General Information and
Assumptions Made
For the cost algorithms presented below for truck haul-
ing of liquid sewage sludge, capital costs include pur-
chase of specially designed tank trucks, as well as
construction of sludge loading facilities at the treatment
plant. The loading facility consists of a concrete slab and
appropriate piping and valving set at a height of 12 ft to
load the tanker from the top. Base annual O&M costs
include driver labor, operational labor, fuel, vehicle main-
tenance, and loading facility maintenance.
16.5.1.2 Process Design and Cost Calculations
(1) Number and capacity of sludge haul trucks.
Liquid sludge is hauled in tanker trucks with capacities
between 1,600 and 6,000 gal. The capacity of the tank
trucks utilized is a function of the volume of sludge to be
hauled per day and the round trip haul time. Special
tanker capacities available are 1,600, 2,000, 2,500,
3,000, 4,000, and 6,000 gal.
(1a) Total volume hauled per trip.
FACTOR = [SV (LT + ULT + RTHT)(365)]/(HPD)(DPY)
where:
FACTOR
SV
LT
ULT
RTHT
Urban travel:
RTHT =
Gallons hauled per trip if only one
truck were utilized.
Daily sludge volume, gpd.
Truck loading time at treatment
plant, hr. Default value = 0.4 hr.
Truck unloading time at application
site, hr. Default value = 1.0 hr. See
Table 16-14 for guidance.
Round trip haul time from treatment
plant to application site, hr. If a
value is not available, this value
can be estimated using an average
mph for truck hauling, as follows:
RTHD
25 miles/hr average speed
Rural travel:
RTHT =
RTHD
35 miles/hr average speed
Highway travel:
RTHT =
where:
RTHD
RTHD
HPD
DPY
45 miles/hr average speed
Round trip haul distance from treatment
plant to application site, miles. If several
sludge application sites are planned
(e.g., private farm agricultural utilization),
use average distance to sites.
Work schedule for hauling, hr/day.
Default value = 7 hr/day.
Number of days/yr sludge is hauled,
days/yr. Default value = 120 days/yr.
See Table 16-15 for guidance.
Table 16-14. Typical Truck Unloading Time as a Function of
Type of Land Application Used
Type of Land Application
Typical Unloading
Time (Hr)
Agricultural
Forest land
Land reclamation
1.0
1.5
1.0
211
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Table 16-15. Typical Days Per Year of Sludge Hauling as a
Function of Types of Application Used and
Geographical Region
Type of Application
Agricultural or land
reclamation utilization
Forest land utilization
Geographical
Region
Northern U.S.
Central U.S.
Sunbelt States
Northern U.S.
Central U.S.
Sunbelt States
Typical Days/Yr
of Sludge Hauling
100
120
140
160
180
200
(1b) Number of vehicles and capacity of each truck.
The number of vehicles is calculated using FACTOR
and Table 16-16.
If FACTOR exceeds 12,000, NTR = Factor/6,000
(Round to next highest integer.)
where:
NTR
= Number of trucks required, from
Table 16-16.
Table 16-16. Number of Vehicles and Capacity of Each Truck
FACTOR, (gal)
Number (NTR) and Capacity (CAP)
of Tanker Trucks, (gal)a
<1,600
>1,600 but <2,500
>2,500 but <4,000
>4,000 but <8,000
>8,000 but <12,000
>12,000
1 at 1,600
1 at 2,500
1 at 4,000
2 at 4,000
2 at 6,000
All 6,000
FACTOR = Gallons hauled per trip if only one truck is used.
CAP = Capacity of tanker trucks required, gal.
NTR = Number of trucks required.
(2) Number of round trips/yr.
NRT = SV (365)/CAP
where:
NRT
SV
CAP
= Number of round trips/yr.
= Daily sludge volume, gpd (see Cal-
culation #1).
= Capacity of tanker trucks required,
gal (see Table 16-16).
(3) Driver labor requirement.
DT = (LT + ULT + RTHT) NRT
where:
DT
LT
= Driver labor requirement, hr/yr.
= Truck loading time at treatment
plant, hr (see Calculation #1).
ULT = Truck unloading time at application
site, hr (see Calculation #1).
RTHT = Round trip haul time from treatment
plant to application site, hr (see Cal-
culation #1).
NRT = Number of round trips/yr (see Calcu-
lation #2).
(4) Annual fuel requirement.
Vehicle fuel usage is a function of truck size. Table 16-17
lists typical fuel usage values for different capacity trucks.
FU = (RTHD)(NRT)/FC
where:
FU
RTHD
NRT
FC
Annual fuel requirement, gal/yr.
Round trip haul distance from treat-
ment plant to application site, miles
(see Calculation #1).
Number of round trips/yr (see Calcula-
tion #2).
Fuel consumption rate, mpg, see
Table 16-17.
Table 16-17. Fuel Use Capacities for Different Sized Trucks
Truck Capacity (CAP) (gal) Fuel Consumption (FC) (mpg)
1,600
2,500
4,000
6,000
(5) Cost of sludge tanker trucks.
TTCOST = (NTR)(COSTSTT)
MSECI
990.8
where:
TTCOST =
NRT
COSTSTT =
MSECI
Total cost of all sludge tanker trucks, $.
Number of round trips/yr (see Calcu-
lation #2).
Cost per sludge tanker truck, ob-
tained from Table 16-18.
Current Marshall and Swift Equip-
ment Cost Index at time cost analy-
sis is made.
Table 16-18. Cost of Tanker Truck
Tanker Capacity (CAP) (gal)
Cost of Truck
(COSTSTT) (1994 $)
1,600
2,500
4,000
6,000
79,000
106,000
132,000
158,000
212
-------
(6) Cost of vehicle loading area facilities.
The tanker truck loading facilities are assumed to
consist of a concrete slab, appropriate piping and
valving to a height of 12 ft to load the tanker from
the top. Cost of the loading area facilities are
assumed to be a function of sludge volume, (SV in
Calculation #1), in gal/yr. The relationship of SVto load-
ing area facilities cost is graduated in a stepped manner.
COSTLA = (COSTLAB)
ENRCCI
5,445.83
where:
COSTLA =
COSTLAB =
ENRCCI =
Total capital cost of loading area
facilities, $.
Base cost of loading area facilities,
$. This is a function of the annual
volume of sludge hauled, SV, in
gal/yr, and can be obtained from
Table 16-19.
Current Engineering News Record
Construction Cost Index at time
cost analysis is made.
Table 16-19. Loading Area Costs Based on Sludge Volume
Annual Volume of Sludge
Hauled (SV x 365) (gal/yr)
Base Cost of Loading Area
Facilities (COSTLAB) (1994 $)
100,000to 500,000
500,000 to 1 ,000,000
1 ,000,000 to 2,000,000
2,000,000 to 4,000,000
4,000,000 to 8,000,000
8,000,000(0 12,000,000
12,000,000(0 16,000,000
16,000,000(020,000,000
20,000,000 and over
27,000
41 ,000
54,000
68,000
82,000
95,000
109,000
122,000
136,000
(7) Annual vehicle maintenance cost.
Maintenance cost per vehicle mile traveled is a function
of truck capacity and initial cost of truck. The factors
listed in Table 16-20 are used to calculate vehicle main-
tenance costs.
VMC = (RTHD)(NRT)(MCM)
MSECI
990.8
where:
VMC
RTHD
NRT
Annual vehicle maintenance cost, $.
Round trip haul distance from treat-
ment plant to application site, miles
(see Calculation #1).
Number of round trips/yr (see Calcu-
lation #2).
MCM = Maintenance cost per mile traveled,
$/mile from Table 16-20.
MSECI = Current Marshall and Swift Equip-
ment Cost Index at time cost analy-
sis is made.
Table 16-20. Vehicle Maintenance Cost Factors
Truck Capacity
(CAP) (gal)
Maintenance Cost (MCM)
$/mile Traveled, (1994 $)
1,600
2,500
4,000
6,000
0.37
0.42
0.47
0.53
(8) Loading area facility annual maintenance cost.
For the purposes of this program, it is assumed that
loading area facilities annual maintenance cost is a
function of loading area facility capital cost.
MCOSTLA = (COSTLA)(0.05)
where:
MCOSTLA = Annual maintenance cost for load-
ing facilities, $/yr.
COSTLA = Total capital cost of loading area fa-
cilities, $ (see Calculation #6).
0.05 = Assumed annual maintenance cost
factor as a function of total loading
area facility capital cost.
(9) Annual cost of operation labor.
COSTLB = (DT)(COSTL)(1.2)
where:
COSTLB =
DT
COSTL
1.2
Annual cost of operation labor, $/yr.
Driver labor requirement, hr/yr (see
Calculation #3).
Cost of labor, COSTL, $/hr. Default
value = $22.97/hr. (ENRCCI/5,445.83).
A factor to account for additional la-
bor required at the loading facility.
(10) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL =
FU
Annual cost of diesel fuel, $/yr.
Annual fuel requirement, gal/yr (see
Calculation #4).
COSTDF = Cost of diesel fuel, $/gal. Default
value = $1.09. (ENRCCI/5,445.83).
213
-------
(11) Total base capital cost.
TBCC = TTCOST + COSTLA
SVCY = (SV)(365)/202
where:
TBCC
TTCOST =
COSTLA =
Total base capital cost, $.
Total cost of all sludge tanker
trucks, $ (see Calculation #5).
Total capital cost of loading area fa-
cilities, $ (see Calculation #6).
(12) Annual operation and maintenance cost.
COSTOM = (VMC) + (MCOSTLA) + (COSTLB) +
(COSTDSL)
where:
COSTOM = Total annual operation and mainte-
nance cost, $/yr.
VMC = Annual vehicle maintenance cost, $
(see Calculation #7).
MCOSTLA = Annual maintenance cost for loading
facilities, $/yr (see Calculation #8).
COSTLB = Annual cost of operation labor, $/yr
(see Calculation #9).
COSTDSL = Annual cost of diesel fuel, $/yr (see
Calculation #10).
16.5.2 Truck Hauling of Dewatered
Sewage Sludge
16.5.2.1 General Information and
Assumptions Made
Capital costs in the cost algorithms presented below for
dewatered sewage sludge transport include construc-
tion of a truck loading facility designed to accommodate
the sludge volume within the operating schedule. Costs
include construction of a concrete loading slab, and
purchase of skip loaders and trucks. Annual O&M costs
include vehicle and loading facility maintenance, driver
and operational labor, and diesel fuel for vehicles.
16.5.2.2 Process Design and Cost Calculations
Same as Calculation #1 for truck hauling of liquid sew-
age sludge, shown in Section 16.5.1 above.
(1) Annual sludge volume hauled, cu yd/yr.
Trucks which haul dewatered sludge are sized in terms
of yd3 of capacity. Therefore, it is necessary to convert
gal of dewatered sludge to yd3 of dewatered sludge.
where:
SVCY
SV
202
= Sludge volume hauled, cu yd/yr.
= Daily sludge volume, gpd.
= Conversion factor, gal/cu yd.
(2) Number and capacity of sludge haul trucks.
Dewatered sludge is hauled in trucks with capacities
between 7 and 36 cu yd. The capacity of the trucks
utilized is a function of the volume of sludge to be
hauled per day and the round trip hauling time. Typical
capacities available are 7, 10,15, 25, and 36 cu yd.
(2a) Total sludge volume hauled per day.
FACTOR = SVCY(LT + ULT + RTHT)/(HPD)(DPY)
where:
FACTOR
SVCY
LT
ULT
RTHT
Cu yd which would have to be hauled
per trip if only one truck were utilized.
Sludge volume hauled, cu yd/yr
(see Calculation #1).
Truck loading time at treatment
plant, hr (see Calculation #1 for liq-
uid sludge, section 16.5.1.2).
Truck unloading time at application
site, hr (see Calculation #1 for liq-
uid sludge, Section 16.5.1.2).
Round trip haul time from treatment
plant to application site, hr (see Calcula-
tion #1 for liquid sludge, Section 16.5.1.2).
(2b) Capacity and number of haul vehicles.
Capacity and number of haul vehicles are calculated
using FACTOR and Table 16-21.
Table 16-21. Capacity and Number of Haul Vehicles
FACTOR (cu yd)
Number (NTR) and Capacity3
of Trucks (CAP) (cu yd)
<7
7 to 10
10 to 15
15 to 25
25 to 36
36 to 50
50 to 72
1 at 7
1 at 10
1 at 15
1 at 25
1 at 36
2 at 25
2 at 36
' NTR = Number of trucks required.
214
-------
If FACTOR exceeds 72, use:
(6) Cost of sludge haul trucks.
NTR =
FACTOR
36
CAP = 36 cu yd.
(Round to next highest integer).
where:
NTR
CAP
(3) Number of round trips/yr.
NRT = (SVCY)/(CAP)
= Number of trucks required. Calcu-
lated from Table 16-21.
= Capacity of truck required, cu yd.
where:
NRT
SVCY
CAP
(4) Driver time.
Number of round trips/yr (round to
next highest integer).
Annual sludge volume hauled, cu
yd/yr (see Calculation #1).
Capacity of truck, cu yd (see Calcu-
lation #2).
Same as Calculation #3 for truck hauling of liquid sew-
age sludge in Section 16.5.1.2.
(5) Annual fuel requirement.
Vehicle fuel usage is a function of truck size. Table
16-22 lists typical fuel usage values for different ca-
pacity trucks.
FU = (RTHD)(NRT)/(FC)
where:
FU
RTHD
NRT
FC
Annual fuel requirement, gal/yr.
Round trip haul distance from
treatment plant to application site,
miles (see Calculation #1 for liq-
uid sludge in Section 16.5.1.2).
Number of round trips/yr (see Calcu-
lation #3).
Fuel consumption rate, miles/gal,
see Table 16-22.
Table 16-22. Fuel Usage Values for Different Sized Trucks
Truck Capacity (CAP) (cu yd)
Fuel Consumption (FC)
(miles/gal)
7
10
15
25
36
TCOSTTRK = (NTR)(COSTTRK)
MSECI
990.8
where:
TCOSTTRK= Total cost of dewatered sludge haul
trucks, $.
NTR = Number of trucks required (see Cal-
culation #2).
COSTTRK = Cost per truck, obtained from Table
16-23.
MSECI = Current Marshall and Swift Equip-
ment Cost Index at time cost analy-
sis is made.
Table 16-23. Costs for Different Sized Trucks
Truck Capacity (CAP) yd3
Cost of Truck
(COSTTRK) (1994 $)
7
10
15
25
36
86,000
129,000
172,000
226,000
282,000
(7) Cost of vehicle loading facilities.
Truck loading facilities are assumed to consist of a con-
crete slab, one or more skip loaders to load the trucks, and
miscellaneous improvements such as drainage, lighting,
etc. Cost of the truck loading facilities are assumed to be
a function of sludge volume in yd3/yr (SVCY in Calculation
#1). The relationship of SVCY to loading area facilities cost
is graduated in a stepped manner and depends on the
number of loading vehicles required.
COSTLA = (COSTLAB)
ENRCCI
5,445.83
where:
COSTLA =
COSTLAB =
ENRCCI =
Total capital cost of loading area fa-
cilities, $.
Base cost of loading area facilities, $.
This is a function of the annual vol-
ume of sludge hauled (SVCY in Calcu-
lation #1) and can be obtained from
Table 16-24.
Current Engineering News Record
Construction Cost Index at time cost
analysis is made.
215
-------
Table 16-24. Loading Area Costs
Annual Volume of Sludge
Hauled (SVCY) (yd3)
Base Cost of Loading Area
Facilities (COSTLAB) (1994 $)
500 to 2,500
2,500 to 5,000
5,000to 10,000
10,000(020,000
20,000 to 40,000
40,000 to 60,000
60,000 to 80,000
80,000to 100,000
100,000 and over
54,000
61 ,000
68,000
109,000
122,000
136,000
204,000
251 ,000
299,000
(8) Annual vehicle maintenance cost.
Maintenance cost per vehicle mile traveled is a function of
truck capacity and initial cost of the truck.The factors out-
lined in Table 16-25 are used to calculate vehicle mainte-
nance costs.
VMC = (RTHD)(NRT)(MCM)
MSECI
990.8
where:
VMC
RTHD
NRT
MCM
MSECI
Annual maintenance cost, $/yr.
Round trip haul distance from treat-
ment plant to application site, miles
(see Calculation #1 for truck hauling
of liquid sewage sludge).
Number of round trips/yr (see Calculation
#3).
Maintenance cost/mile travelled, $/mile
from Table 16-25.
Current Marshall and Swift Equipment
Cost Index at time cost analysis is made.
Table 16-25. Vehicle Maintenance Cost Factors
Truck Capacity (CAP) yd3
Maintenance Cost (MCM)
$/mile Traveled (1994 $)
7
10
15
25
36
0.34
0.42
0.49
0.59
0.70
(9) Annual maintenance cost for loading area facilities.
For the purposes of this program, it is assumed that loading
area facilities annual maintenance cost is a function of
loading area facilities capital cost.
MCOSTLA = (COSTLA)(0.05)
where:
MCOSTLA =
COSTLA =
0.05
Annual maintenance cost for loading
area facilities, $/yr.
Total capital cost of loading area facili-
ties, $ (see Calculation #7).
Assumed annual maintenance cost
factor as a function of total loading
area facilities capital cost.
(10) Annual cost of operational labor.
COSTLB = (DT)(COSTL)(1.2)
where:
COSTLB
DT
COSTL
1.2
Annual cost of operational labor, $/yr.
Driver labor requirement, hr/yr (see
Calculation #3 for truck hauling of
liquid sludge, Section 16.5.1.2).
Cost of labor, $/hr. Default value =
$22.97/hr. (ENRCCI/5,445.83).
A factor to account for additional la-
bor required at loading facility.
(11) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL =
FU
Annual cost of diesel fuel, $/yr.
Annual fuel requirement, gal/yr (see
Calculation #5).
COSTDF = Cost of diesel fuel, $/gal. Default
value = $1.09/gal. (ENRCCI/5,445.83).
(12) Total base capital cost.
TBCC = TCOSTTRK + COSTLA
where:
TBCC
TCOSTTRK =
Total base capital cost, $.
Total cost of dewatered sludge haul
trucks, $ (see Calculation #6).
COSTLA = Total capital cost of loading area fa-
cilities, $.
(13) Annual operation and maintenance cost.
COSTOM = (VMC) + (MCOSTLA) + (COSTLB) +
(COSTDSL)
where:
COSTOM = Total annual operation and mainte-
nance cost, $/yr.
VMC = Annual vehicle maintenance cost,
$/yr (see Calculation #8).
MCOSTLA = Annual loading facility maintenance
cost, $/yr (see Calculation #9).
COSTLB = Annual cost of operation labor, $/yr
(see Calculation #10).
216
-------
COSTDSL = Annual cost of diesel fuel, $/yr (see
Calculation #11).
16.5.3 Long-Distance Pipeline Transport of
Liquid Sewage Sludge
16.5.3.1 General Information and
Assumptions Made
Friction losses associated with sludge pipelines have been
taken into account in the cost algorithms presented below
by applying a "K" factorto an otherwise unmodified Hazen-
Williams formula. This "K" factor, which is a function of both
sludge solids content and sludge type, is discussed in
more detail in Calculation #2 below. Pipelines with coated
interiors (e.g., glass or cement mortar linings) are often
used as a means of reducing friction loss. Because dried
sludge can "cake" on interior pipe walls, flushing pipelines
with clean water or treated effluent is also commonly
practiced as a means of reducing friction loss due to such
"caking." In addition, flushing has been used as a means
for preventing sludge solids from settling and hardening in
dormant pipelines.
Cost considerations for these algorithms include: pipe-
line and pumping station construction costs and O&M
labor, materials, and energy requirements. Large vari-
ations in construction costs are associated with certain
route-specific variables, such as the number of river
crossings or the fraction of pipeline length requiring
excavation of rock. To obtain the best results, the user
is encouraged to obtain or plot a viable pipeline route on
a suitable scale map and input the most accurate design
parameter values possible. Cost of right-of-way acquisi-
tion is not included in these algorithms.
16.5.3.2 Process Design and Cost Calculations
(1) Pipeline diameter.
PD = 12 [SV/(63,448)(HPD)]° 5
(Round to next highest even integer.)
where:
PD
SV
63,488
HPD
Pipeline diameter, inches.
Daily sludge volume, gpd.
Conversion factor = (3.1416/4)[(3
ft/sec)(7.48 gal/cu ft)(86,400
sec/day)/(24 hr/day)]
Hours per day of pumping, HPD, hr.
Note: Pipeline is assumed to be flowing full.
(2) Head loss due to pipeline friction.
PFL = K [(SV)/(HPD)(PD)263(C)(16.892)]1 852
where:
PFL
K
2.63
C
Head loss due to pipe friction, ft/ft. Is
function of pipe diameter, velocity,
and "C" value selected.
Coefficient to adjust for increased
head loss due to sludge solids con-
tent. No default value. Pipeline fric-
tion losses may be much higher for
transporting sewage sludge than for
transporting water, depending on
such factors as the sludge concentra-
tion (percent solids by weight) and
the type of sludge (raw primary, di-
gested, etc.). The user is cautioned
that the K factors provided in Table
16-26 are highly simplified and may
give inaccurate results for pipeline
friction loss. An elaborate method for
design engineering calculations is
provided in U.S. EPA, 1979.
Hazen-Williams constant.
Hazen-Williams friction coefficient.
Default value = 90.
2.63
16.892 = (646,000 gpd/cfs)/(24)(2.31)(12)
Table 16-26. Factors for Various Sludge Concentrations and
Two Types of Sludge
K Factor
Solids Concentration
Percent by Weight
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Digested
Sludge
1.05
1.10
1.25
1.45
1.65
1.85
2.10
2.60
Untreated
Primary Sludge
1.20
1.60
2.10
2.70
3.40
4.30
5.70
7.20
(3) Head required due to elevation difference.
HELEV = ELEVMX - PSELEV
where:
HELEV = Head required due to elevation
difference, ft.
ELEVMX = Maximum elevation in the pipeline, ft.
PSELEV = Elevation at the start of the pipe-
line, ft.
217
-------
(4) Total pumping head required.
H = [(PL)(PFL) + HELEV]
(7) Horsepower required per pump station.
HPS = HP/NOPS
where:
H
PL
PFL
HELEV
Total pumping head required, ft.
Pipeline length, ft.
Head loss due to pipe friction, ft/ft
(see Calculation #2).
Head required due to elevation
difference, ft (see Calculation #3).
(5) Number of pumping stations.
NOPS = H/HAVAIL
If the decimal ending for the MOPS resultant is greater than
or equal to 0.25, then round up to the next higher integer. If
it is less than 0.25, round down. Thus, if MOPS is 2.35, use
3 pump stations. If MOPS = 2.10, use 2 pump stations.
where:
NOPS
H
H AVAIL
Number of pumping stations.
Total pumping head required, ft.
Head available from each pumping sta-
tion, ft. This is a function of the type of
pump, sludge flow rate, and whether
or not pumps are placed in series. Ob-
tain this value from Table 16-27.
Table 16-27. Head Available from Each Pumping Station
Pipe Diameter (PD)
(inches)
4& 6
8
10& 12
14& 16
18&20
Head Available
(HAVAIL) (ft)
450
260
230
210
200
(6) Total horsepower required for pump stations.
HP = (H)(SV)(8.34)/(HPD)(60)(0.50)(33,000)
where:
HP = Total pumping horsepower required, hp.
H = Total pumping head required, ft
(see Calculation #5).
SV = Daily sludge volume, gpd (see Cal-
culation #1).
HPD = Hours per day of pumping, HPD, hr
(see Calculation #1).
33,000 = Conversion factor, hp to ft-lb/min.
60 = Conversion factor, min/hr.
0.50 = Assumed pump efficiency.
8.34 = Density of water, Ib/gal.
where:
HPS
HP
NOPS
Horsepower required per pump
station, hp.
Total pumping horsepower required,
hp (see Calculation #6).
Number of pumping stations (see
Calculation #5).
(8) Electrical energy requirement.
E = [(0.0003766)(1 -2)(H)/(0.5)(0.9)](SV)
(365)(8.34)/1,000
where:
E
= Electrical energy, kWhr/yr.
0.0003766 = Conversion factor, kWhr/1,000
ft-lb.
8.34 = Density of water, Ib/gal.
1.2 = Assumed specific gravity of sludge.
0.5 = Assumed pump efficiency.
0.9 = Assumed motor efficiency.
(9) Operation and maintenance labor requirement.
L = (NOPS)(LPS) + (PL)(0.02)
where:
L
NOPS
LPS
PL
0.02
Annual operation and maintenance
labor, hr/yr.
Number of pumping stations (see
Calculation #5).
Annual labor per pump station, hr/yr.
This is a function of pump station horse
power, HPS, as shown in Table 16-28.
Pipeline length, ft (see Calculation #4).
Assumed maintenance hr/yr per ft
of pipeline, hr/ft.
Table 16-28. Annual Labor Per Pump Station
Pump Station
Horsepower (HPS)
Annual O&M Labor
(LPS) (hr)
25
50
75
100
150
200
250
300
350
700
720
780
820
840
870
910
940
980
218
-------
(10) Cost of installed pipeline.
COSTPL = (1 + 0.7 ROCK)(1 + 0.15 DEPTH)
PL (COSTP,
where:
COSTPL =
0.7 =
ROCK =
0.15 =
DEPTH =
PL =
COSTP =
ENRCCI =
Cost of installed pipeline, $.
Assumed fraction of pipeline length
that requires rock excavation.
Fraction of pipeline length that re-
quires rock excavation.
Assumed fraction of pipeline length
that does not require rock excava-
tion, but is greater than 6 ft deep.
Fraction of pipeline length that does
not involve rock excavation, but is
greater than 6 ft deep.
Pipeline length, ft (see Calculation #4).
Pipeline cost per unit length, $/ft. This
cost is obtained from Table 16-29.
Current Engineering News Record
Construction Cost Index at time
analysis is made.
Table 16-29. Pipeline Cost
Pipeline Diameter (PD)
(inches)
Installed Cost (COSTP)
($/ft, 1994 $)a
4
6
8
10
12
14
16
18
20
28.68
30.99
34.39
37.93
41.33
48.26
52.88
58.59
68.92
Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(11) Cost of pipeline crossings.
COSTPC = [NOH($26,000) + NODH($52,000) +
NRC($19,000) + NOSR($116,000) +
NOLR($462,000)] ENRCCI
where:
COSTPC
NOH
NODH
5445.83
Cost of pipe crossings, $.
Number of 2- or 4-lane highway
crossings. Default value = 1.
Number of divided highway cross-
ings, NODH. Default value = 0.
NRC = Number of railroad tracks (2
rails/track) crossed. Default value = 2.
NOSR = Number of small rivers crossed. De-
fault value = 0.
NOLR = Number of large rivers crossed. De-
fault value = 0.
ENRCCI = Current Engineering News Record
Construction Cost Index at time
analysis is made.
(12) Cost of pump stations.
COSTPS = NOPS [$218,000 +
$3,600 (HPS-25)]
where:
COSTPS
NOPS
HPS
MSECI
Construction cost of all pump stations.
Number of pumping stations (see
Calculation #5).
Horsepower required per pump sta-
tion, hp (see Calculation #7).
Current Marshall and Swift Equip-
ment Cost Index at time analysis is
made.
Note: If HPS is less than 25 hp, then, for this calculation,
let HPS = 25 hp.
(13) Annual cost of electrical energy.
COSTEL = (E)(COSTE)
where:
COSTEL =
E
COSTE
Total annual cost of electricity, $/yr.
Electrical energy requirement, kWhr/yr.
Unit cost of electricity, $/kWhr. De-
fault value = $0.121/kWhr
(ENRCCI/5445.83).
(14) Annual cost of operation and maintenance labor.
COSTLB = (L)(COSTL)
where:
COSTLB
L
COSTL
Annual cost of operation and main-
tenance labor, $/yr.
Operation and maintenance labor
requirement, hr/yr.
Unit cost of labor, $/hr. Default
value = $22.97/hr
(ENRCCI/5445.83).
(15) Cost of pumping station replacement parts and
materials.
COSTPM = NOPS (PS)
MSECI
990.8
219
-------
where:
COSTPM
PS
MSECI
Annual cost of pumping station re-
placement parts and materials, $/yr.
Annual cost of parts and supplies for
a single pumping station, $/yr. This
cost is a function of pumping station
horse power as shown in Table 16-30.
Current Marshall and Swift Equipment
Cost Index at time analysis is made.
Table 16-30. Annual Cost of Pumping Station Parts and
Supplies
Pump Station
Horsepower (HPS)
Annual Parts and Supplies3
Cost (PS) ($/Yr, 1994 $)
25
50
75
100
150
200
250
300
350
1,420
1,490
1,680
1,820
1,980
2,100
3,750
3,910
4,100
Costs were taken from EPA's 1985 Cost Estimation Handbook (U.S.
EPA, 1985) and inflated to 1994 price levels using the MSECI.
(16) Total base capital cost.
TBCC = COSTPL + COSTPC + COSTPS
where:
TBCC
COSTPL
COSTPC
COSTPS
Total base capital cost, $.
Cost of installed pipeline, $.
Cost of pipeline crossings, $.
Cost of pump stations, $.
(17) Total annual operation and maintenance cost.
COSTOM = COSTEL + COSTLB + COSTPM
where:
COSTOM = Total annual operation and mainte-
nance cost, $/yr.
COSTEL = Annual cost of electrical energy, $/yr.
COSTLB = Annual cost of operation and main-
tenance labor, $/yr.
COSTPM = Cost of pumping station replace-
ment parts and materials, $/yr.
16.6 Example of Preliminary Cost
Estimation for Agricultural Land
Application to Cropland
The following preliminary cost estimation for land applica-
tion of sewage sludge to cropland is for a midwestern
citygeneratingadailysludgevolumeofl 31 ,894gpd(20
dry t/day, 22 T/day).1 The sludge has a suspended
solids concentration of 4 percent and the appropriate
application rate for growing corn at this site was de-
termined to be 4 T/ac/yr (9 t/ha/yr).
16.6. 1 Process Design and Cost Calculations
(1) Calculate dry solids applied to land per year.
TDSS = [(SV)(8.34)(SS)(SSG)(365)]/(2,000)(100)
= Dry solids applied to land, Tons/yr.
= 131,894gpd.
=4 percent.
= Calculate using the following equations:
- SS)/100) + (SS)/(1.42)(100)]
- 4)/100)
where:
TDSS
SV
SS
SSG
SSG =
SSG =
SSG = 1.01
TDSS = [(131,894)(8.34)(4)(1.01)(365)]/(2,000)(100)
TDSS = 8,126 Tons/year
(2) Sludge application area required.
SOAR = (TDSS)/(DSAR)
where:
SOAR
TDSS
DSAR
= Farm area required for sludge appli-
cation, ac.
= 8,126 Tons/yr.
= 4 Tons/ac/yr.
SOAR = (8,126)/(4)
SOAR = 2,302 ac.
(3) Hourly sludge application rate.
HSV = (SV)(365)/(DPY)(HPD)
where:
HSV = Hourly sludge application rate, gal/hr.
SV = 131,894gpd.
DPY = 120 days/yr from Table 16-1.
HPD = 8 hr/day.
HSV= (131,894)(365)/(120)(8)
HSV= 50,147 gal/hr.
1 See Appendix D for equations for converting sludge volume to dry
metric tons.
220
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(4) Capacity of onsite mobile sludge application vehicles.
It is assumed that the sludge has already been transported
to the private farm land application site by a large-haul
vehicle. The onsite mobile application vehicles accept the
sludge from the transport vehicle and proceed to the
sludge application area to apply the sludge.
(4a) Capacity and number of onsite mobile sludge ap-
plication vehicles.
The capacity and number of onsite mobile sludge appli-
cation vehicles required is determined by comparing the
hourly sludge volume, (HSV), with the vehicle sludge
handling rate, (VHRCAP), as shown in Table 16-2.
Since the HSV is 50,147 gal/hr, the number of 4,000-gal
capacity vehicles required is calculated by:
NOV = HSV/6,545 (round to the next highest integer)
FRPH
SOAR
= 0.5.
= 2,032 ac.
where:
NOV
= Number of onsite sludge application
vehicles.
= 50,147 gal/hr.
HSV
NOV = 50,147/6,545
NOV = 8
(4b) The average round trip onsite cycle time (CT) for
mobile sludge application vehicles with a capacity of
4,000 gal. is 33 from Table 16-3.
(4c) The VHRCAP for a single vehicle is 6,545 from
Table 16-4.
(5) Total land area required.
TLAR = (1 + FWWAB)(SDAR)
where:
TLAR
FWWAB
SOAR
Total land area required for agricul-
tural land application site, ac.
0.4.
2,032 ac.
TLAR = (1 + 0.4)(2,032)
TLAR = 2,845 ac.
(6) Lime addition required for soil pH adjustment to a
value of at least 6.5.
TLAPH = (FRPH)(SDAR)
where:
TLAPH = Total land area requiring lime addi-
tion, ac.
TLAPH = (0.5)(2,032)
TLAPH = 1,016 ac.
(7) Total land area requiring light grading.
TLARLG = (FRLG)(SDAR)
where:
TLARLG = Total land area requiring light
grading, ac.
FRLG = 0.3.
SOAR = 2,032 ac.
TLARLG = (0.3)(2,032)
TLARLG = 610 ac.
(8) Annual operation labor requirement.
L = 8 (NOV)(DPY)/0.7
where:
L
NOV
DPY
8
0.7
Annual operation labor requirement,
hr/yr.
8
120 days/yr.
Hr/day assumed.
Efficiency factor.
L = 8 (8)(120)/0.7
L = 10,971 hr/yr.
(9) Annual diesel fuel requirement for onsite mobile
sludge application vehicles.
FU = (HSV)(HPD)(DPY)(DFRCAP)/(VHRCAP)
where:
FU
HSV
HPD
DPY
DFRCAP
VHRCAP
Annual diesel fuel usage, gal/yr.
50,147 gal/hr.
8 hr/day.
120 days/yr.
6 gal/hr from Table 16-5.
6,545 gal/hr.
FU = (50,147)(8)(120)(6)/(6,545)
FU = 44,132 gal/yr.
(10) Cost of land (COSTLAND) is zero because it is
assumed that the application of sewage sludge is on
privately owned farm land.
221
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(11) Cost of lime addition to adjust pH of soil.
COSTPHT = (TLAPH)(COSTPHT)
where:
COSTPHT = Cost of lime addition, $.
TLAPH = 1,016ac.
PHCST = $82/ac., this value assumes 2 Tons
of lime/ac requirement.
COSTPHT = (1,016)($82)
COSTPHT = $83,312
(12) Cost of light grading earthwork.
COSTEW = (TLARLG)(LGEWCST)
where:
COSTEW = Cost of earthwork grading, $.
TLARLG = 610ac.
LGEWCST= $1,359/ac.
COSTEW = (610)($1,359)
COSTEW = $828,990
(13) Cost of onsite mobile sludge application vehicles.
MSECI
COSTMAV = (NOV)(COSTPV)
990.8
where:
COSTMAV = Cost of onsite mobile sludge appli-
cation vehicles, $.
NOV = 8.
COSTPV = $185,000 from Table 16-6.
MSECI = Current Marshall and Swift Equipment
Cost Index at time of analysis is 990.8.
COSTMAV = (8)($1 85,000)
COSTMAV = $1 ,480,000
(14) Annual cost of operation labor.
COSTLB = (L)(COSTL)
where:
COSTLB = Annual cost of operation labor, $/yr.
L = 10,971 hr/yr.
COSTL = Cost of operation labor, $22.97/hr.
COSTLB = (1 0,971 )($22.97)
COSTLB = $252,004
(15) Annual cost of diesel fuel.
COSTDSL = (FU)(COSTDF)
where:
COSTDSL = Annual cost of diesel fuel, $/yr.
FU = 44,132 gal/yr.
COSTDF = Cost of diesel fuel, $1.09/gal.
COSTDSL = (44,132)($1.09)
COSTDSL = $48,104
(16) Annual cost of maintenance for onsite mobile
sludge application vehicles.
VMC = [(HSV)(HPD)(DPY)
(MCSTCAP)/(VHRCAP)]
where:
VMC =
HSV =
HPD =
DPY =
MCSTCAP =
VHRCAP =
MSECI =
Annual cost of vehicle mainte-
nance, $/yr.
50,147 gal/hr.
8 hr/day.
120 days/yr.
$9.45/hr from Table 1 6-7.
6,545 gal/hr.
Current Marshall and Swift Equip-
ment Cost Index at time of analysis
is 990.8.
VMC = [(50,147)(8)(120)($9.45)/(6,545)]
VMC = $69,509
990.8
990.8
(17) Annual cost of maintenance for land application site
(other than vehicles) including monitoring, recordkeep-
ing, etc.
SMC = [(TLAR)(16)]
ENRCCI
5,445.83
where:
SMC
TLAR
16
ENRCCI
Annual cost of maintenance (other
than vehicles), $/yr.
2,845 ac.
Annual maintenance cost, $/ac.
Current Engineering News Record
Construction Cost Index at time of
analysis is 5445.83.
SMC = [(2,845)(16)]
SMC = $45,520
5,445.83
5,445.83
222
-------
(18) Total base capital cost.
TBCC = COSTLAND + COSTPHT + COSTEW
+ COSTMAV
where:
TBCC = Total base capital cost of agricultural
land application program using onsite
mobile sludge application vehicles, $.
COSTLAND = $0.
COSTPHT = $83,312.
COSTEW = $828,990.
COSTMAV = $1,480,000.
TBCC = $0 + $83,312 + $828,990 + $1,480,000
TBCC = $2,392,302
(19) Total annual operation and maintenance cost.
COSTOM = COSTLB + COSTDSL + VMC + SMC
where:
COSTOM = Total annual operation and mainte-
nance cost for agricultural land
application program using onsite
mobile sludge application vehicles, $/yr.
COSTLB = $252,004/yr.
COSTDSL = $48,104/yr.
VMC = $69,509/yr.
SMC = $45,520/yr.
COSTOM = $252,004 + $48,104 + $69,509 + $45,520
COSTOM = $415,137/yr.
16.7 References
Chemical engineering. In: Marshall and Swift equipment cost index.
September 1994. 101(9).
Engineering news record. In: ENR construction cost index. Septem-
ber 5, 1994. p. 96.
Oil and Gas Journal. September 12, 1994. p. 109.
U.S. EPA. 1985. Handbook: Estimating sludge management costs.
EPA/625/6-85/010. Cincinnati, OH.
U.S. EPA. 1979. Process design manual for sludge treatment and
disposal. EPA/625/1-79/011. Cincinnati, OH.
223
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Appendix A
Case Studies
This appendix presents four cases studies illustrating land application at agricultural, forest, and reclamation sites.
The case studies include:
• Madison Metropolitan Sewerage District (MMSD), Madison, Wisconsin. The MMSD applies approximately 20
dry tons of sewage sludge per day to private farmland. Reprinted from Document Long-Term Experience of
Biosolids Land Application Programs, Water Environment Research Foundation, 1993.
• Metro Wastewater Reclamation District (MWRD), Denver, Colorado. The MWRD produces 70 dry tons of sewage
sludge per day, which are either applied to agricultural land or composted and sold to the public. Reprinted from
Document Long-Term Experience of Biosolids Land Application Programs, Water Environment Research Foun-
dation, 1993.
• The Municipality of Metropolitan Seattle (Metro), Seattle, Washington. Metro has applied sewage sludge to
private forest land, with 19,000 dry tons applied to date. Reprinted from The Future Direction of Municipal Sludge
(Biosolids) Management: Where We Are and Where We're Going, Proceedings, Volume 1, Water Environment
Research Foundation, 1992.
• Venango County, Pennsylvania, Abandoned Mine Land Reclamation. Sewage sludge was applied in a single
application at a rate of 184 mg/ha.
These case studies provide valuable insights into design, operation, monitoring, public relations, and other aspects
of programs representing a range of sizes and geographical locations. It should be noted that, in some cases, these
programs will need to make minor operational changes to achieve compliance with the Part 503 regulation.
225
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MADISON METROPOLITAN SEWERAGE DISTRICT, MADISON, WI
Contact Person: David S. Taylor
Madison Metropolitan Sewerage District
1610 Moorland Road
Madison, WI 58713
Phone Number: (608) 222-1201
Average flow: 37 mgd
Design capacity of WWTP: 50 mgd
Dry tons of biosolids/day: 20
Type of biosolids: anaerobically digested
Biosolids management options: land application
Application method: injection
Started application: 1974
5.1 Program Overview
Wastewater treatment at the Nine Springs WWTP started in 1933. Until 1942, anaerobically
digested biosolids was air dried and applied to farmland as a fertilizer/soil conditioner. Because
of the manpower shortage during World War II, the system was abandoned in favor of a lagoon
storage system. In 1974, after evaluating several alternatives, the Madison Metropolitan
Sewerage District (MMSD) decided to begin land applying the biosolids to private farmland.
Currently all biosolids produced at the Nine Springs Wastewater Treatment Plant (WWTP) are
land applied. The design capacity of this activated biosolids treatment plant is 50 mgd. Current
flow is around 37 mgd. About 15% of the wastewater comes from industrial sources. The raw
sludge is stabilized by anaerobic digestion, and the resulting biosolids are marketed to farmers
226
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through the Metrogro™ Program. Current biosolids production is approximately 20 dry tons per
day. The MMSD is also removing biosolids from the lagoons, resulting in a 50 percent increase
In the quantity ot biosolids land applied.
Biosolids are thickened by gravity belt thickeners to approximately 6% total solids. The
thickened solids are transported directly to land application, to off-site storage lagoons, or to
storage lagoons located adjacent to the treatment plant. Prior to off-site transport, the thickened
or dredged biosolids are pumped to a 100,000 gallon holding basin at the truck loading station.
The biosolids dredged from the lagoons have a total solids concentration between 4 and 5
percent. From the holding basin the biosolids are pumped to a 50,000-gallon elevated loading
well from which biosolids can be pumped to the transport trucks. After a truck is loaded any
spilt biosolids are washed off using the on-site washing facilities that are available at the loading
site. The MMSD owns six transport trucks, three mobile storage tanks, and four application
vehicles.
Liquid biosolids are transported to the land application site using 5,500-gallon vacuum trucks
that are compatible with the weight limits on the local roads. The trucks discharge the biosolids
into a 12,000-gallon mobile storage tank located at the application site. A 3,500-gallon
application vehicle withdraws biosolids from the storage tank, and injects them 6 to 8 inches
beneath the soil surface. Figure 5-1 shows a typical storage tank and application vehicle.
Two trucks normally supply one storage tank and application vehicle. The use of the storage tank
has resulted in a 25% increase in productivity. Usually the storage tank stays in one place
during the application to minimize the size of the staging area. After the application is complete,
the staging area is tilled to counteract the compaction caused by the truck traffic. One
application vehicle is capable of spreading biosolids over 8 to 10 acres during a 10-hour
operating period. The biosolids injection vehicles have been modified by increasing the number
of injection shanks to 6 per vehicle, and by adding a drag behind the injectors to smooth the
disturbed soil as shown in Figure 5-2. During the application season the vehicles return to the
treatment plant only for major repairs.
227
-------
Figure 5-1. Storage tank and application vehicle.
Figure 5-2. Application vehicle.
228
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The MMSD has permits for 250 to 300 farms to apply biosolids or approximately 30,000 acres
of permitted land with 3,000 to 4,000 acres used annually. Biosolids are applied at agronomic
rates ranging from 3 to 5 dry tons per acre per year depending on the crop. The biosolids
cumulative loading on the field included in this study (site 22, Field 2) is approximately 80 dry
tons per acre. Field corn is the primary crop, but other crops include sweet corn, soybeans, and
alfalfa (at seedbed preparation). No minimum size has been established for fields; however the
MMSD prefers to use large fields to help reduce operating costs. The average transport distance
is about 13 miles, while the maximum distance is 22 miles.
During peak application periods, i.e. spring and fall, biosolids are applied 10 to 12 hours per day,
6 days per week. Contract operators, under MMSD supervision, are employed to assist the
MMSD, and truck traffic becomes heavy with as many as 100 truckloads hauled every day. This
truck traffic can generate numerous complaints from the public. Participating farmers have
expressed concern over the use of contractors during the peak application season. Most
contractors use five-wheeled application vehicles, which the farmers feel cause more soil
compaction than the MMSD's four-wheeled application vehicles.
The MMSD is closing both the on-site and off-site storage lagoons, except for a portion of the
on-site lagoons which will be retained for emergency storage. Concurrently with the lagoon
closure plan, the MMSD is constructing tank storage facilities for 18 million gallons of biosolids
or for 180 days at maximum monthly design flow.
The MMSD uses a computerized recordkeeping and tracking system for all aspects of its
Metrogro Program. The MMSD works closely with the Wisconsin Department of Natural
Resources (WDNR) to ensure that reports are formatted to ensure a fast and efficient transfer of
information to the regulating agency.
229
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5.2 Monitoring
As shown in Table 5-1, the monitoring program includes sampling and analyses of biosolids,
soil, crop/tissue/grain, and groundwater. Samples of biosolids are collected from each truck and
combined into a daily composite sample. The daily composite is analyzed for total solids, total
kjeldahl nitrogen and ammonia nitrogen. Weekly and monthly composite samples are made from
the daily composites. The monthly samples are analyzed for the parameters in Table 5-1. A full
priority pollutant analysis is conducted once each year.
Surface soil samples (0 to 6 inch depth) are collected from each field when the site is initially
permitted with the WDNR. Active application sites are resampled every three years. The surface
soil samples are used to determine crop nutrient requirements, as well as the soil cation exchange
capacity (CEC) and soil pH. Where necessary, the MMSD requires that farmers lime fields to
meet the minimum soil pH requirement of 6.5 that is specified by the WDNR.
Deep core (4 feet) soil samples and plant tissue samples are collected from representative soil
types encountered in the Metrogro program. These samples are analyzed for the parameters listed
in Table 5-1. Deep core samples are collected from these soil types prior to the initial biosolids
application, and every three years thereafter. These samples are used to evaluate whether metals
are moving from the zone of incorporation. Plant tissue samples are collected from these sites
every three years, and the metal concentrations are compared to available risk-based criteria.
Groundwater samples are collected from private wells located near land application sites.
Approximately 750 private wells are sampled each year. The samples are analyzed for nitrate,
chloride, sulfate, coliform bacteria, and zinc. Results of the groundwater analyses are provided
to the well owner.
230
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Table 5-1
Parameters Monitored by Madison Metropolitan Sewerage District
Parameter
Total Solids
Total Volatile Solids
PH
Cation Exchange Capacity (CEC)
Total Kjeldahl Nitrogen (TKN)
Ammonium-Nitrogen
Nitrate-Nitrogen
Phosphorus
Potassium
Cadmium
Chloride
Chromium
Copper
Nickel
Lead
Zinc
PCB (lagoon)
Arsenic
Molybdenum (lagoon)
Selenium (lagoon)
Pesticides
Phenol
Tetrachloroethylene
Trichloroethylene
Vinyl Chloride
Ascaris
Coliform
Salmonella
Biosolids Soil Crops Groundwater
X
X
X X
X
X
X
X X
X X
X X
XXX
X
XX X
XXX
XXX
XXX
XXX X
X
X
X
X
X
X
X
X
X
X
X X
X
231
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Table 5-2
Average Concentrations in MMSD Digested Biosolids
Parameter
pH
Total Solids
TKN
Ammonium-Nitrogen
Phosphorus
Potassium
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
1989
7.4
2.2
10.6
5.5
2.8
1.0
4.1
15.0
96.6
683
145
6.7
18.4
46.2
2.9
1,200
1990
7.5
4.8
8.2
3.2
2.5
0.7
.
6.9
13.1
107
671
152
8.1
18.9
46.7
5.3
1,250
1991
7.5
5.5
7.5
2.1
2.6
0.6
4.7
11.2
71.5
634
133
5.9
15.3
45.4
8.2
1,060
1992
7.6
5.7
7.4
2.0
2.6
0.7
3.7
13.7
81.6
609
134
4.8
12.2
42.9
6.3
1,040
The deep core soil, plant tissue, and groundwater monitoring programs are not required by the
WDNR. They are conducted on a voluntary basis by the MMSD in an effort to increase both
farmer and the general public's confidence in the Metrogro program. Soil and plant samples have
also been collected from a number of test sites, with controlled, replicated biosolids applications.
5.3 Results
Table 5-2 lists the average digested biosolids quality. The values for the lagooned biosolids are
similar. Of the organics tested, only bis-(2-ethylhexyl) phthalate was above the detection limit
and measured 6.3 mg/kg. Although bis-(Z-ethylhexyl) phthalate is a common laboratory
contaminant and was found in some of the blanks, it is commonly found in biosolids. Parameter
232
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concentrations in biosolids are currently below the Pollutant Concentration limits of 40 CFR
Part 503.
Figures 5-3 through 5-5 show the soil concentrations for cadmium, nickel, and lead, at different
soil depths on site 22, Field 2. The metal concentrations in the soil do not appear to be well
correlated with the loading. Nickel concentrations in the soil are declining; cadmium
concentrations stay fairly constant in the surface soil, but are declining in the subsoil; and lead
concentrations in the surface soil increased much faster than would be expected from the loading
but show little change in the lower soil layers.
The plant uptake of metals was investigated by the MMSD through a field experiment with three
replications. Fertilizer, biosolids at agronomic rates, and biosolids at twice the agronomic rates
were applied to the field. Table 5-3 shows the cumulative metals loadings for the three test
fields and the soil concentrations at the conclusion of the study in 1987. Corn was grown, and
samples were taken from ear leaf and grain tissues. Results from the ear leaf analyses are shown
in Table 5-4. Significant increases in the zinc and cadmium and decreases in the copper
concentrations could be detected in the ear leaf tissues. Grain tissue concentrations were always
significantly lower than ear leaf concentrations.
The groundwater monitoring results have shown a trend for increasing nitrate and chloride
concentrations over time. The lack of background data for coliform bacteria in many wells made
it difficult to evaluate changes in water quality relative to this parameter. A long-term
groundwater monitoring study was initiated by the MMSD in 1982 to compare groundwater
quality trends at Metrogro application sites to sites where commercial fertilizers and animal
manures were used. The study found no significant difference in groundwater quality trends
between sites where Metrogro was used and sites where commercial fertilizers/animal manures
were used. Thus, while the farming practices seem to impact the groundwater, the impact from
Metrogro applications seems to be no different than the impact of traditional farming practices.
233
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2.5n
77 78 79 80 81 82 83 84 85 86 87 88
Year
Figure 5-3. Cadmium concentrations in the soil on site 22, Field 2.
-*• 0-10 inch
-'-10-24 inch
-*- 24 - 48 inch
-*- 0-10 inch
-1-10-24 inch
-*- 24 - 48 inch
77 78 79 80 81 82 83 84 85 86 87 88
Year
Figure 5-4. Nickel concentrations in the soil on site 22, Field 2.
234
-------
-*- 0-10 inch
-i-10 -24 inch
-*- 24 - 48 inch
77 78 79 80 81 82 83 84 85 86 87 88
Year
Figure 5-5. Lead concentrations in the soil on site 22, Field 2.
Table 5-3
Cumulative Metals Loadings and Soil Test Levels for Plant Uptake Study
Treatment
Fertilizer
Biosolids
Biosolids 2X
Fertilizer
Biosolids
Biosolids 2X
Cd
0
1.31
2.62
0.27
0.63
0.81
Cr
N/A*
N/A
N/A
17.2
19.2
24.1
Cu
Cumulative Loading fib/acre)
0
30.6
61.2
1987 Soil Test (mg/kg)
16.8
23.9
29.4
Ni
0
3.0
6.0
13.8
14.2
15.7
Pb
0
12.5
23.9
23.7
25.9
28.1
Zn
0
97.1
194
95
113
134
f Data not available.
235
-------
Table 5-4
Metal Concentrations in Corn Ear Leaf Tissue
Year
.78
79
80
81
82
83
84
85
86
87
78
79
80
81
82
83
84
85
86
87
78
79
80
81
82
83
84
85
86
87
Cd
0.13
0.22
0.14
0.15
0.22
0.18
0.18
0.10
0.19
0.06
0.17
0.28
0.41
0.31
0.43
0.27
0.30
0.17
0.27
0.09
0.20
0.48
0.70
0.41
0.52
0.36
0.33
0.23
0.31
0.14
Cr
0.51
0.63
0.39
0.44
0.51
6.48
3.60
2.03
1.72
1.02
0.62
0.68
0.41
0.56
0.67
6.41
3.91
2.00
1.81
1.42
0.54
0.51
0.44
0.52
0.66
4.78
6.33
2.00
1.86
2.13
Cu Ni
- mg/kg (dry weight)
Fertilizer
13.8
12.4
14.7
13.0
16.8
10.2
12.4
10.8
11.0
7.6
Biosolids
13.1
11.8
14.0
12.3
14.2
10.0
11.4
9.6
11.2
8.0
Biosolids 2x
13.8
12.5
14.7
12.3
14.6
9.3
11.5
10.2
11.8
8.2
0.87
1.00
0.75
1.08
1.31
5.27
3.24
1.75
1.13
0.93
0.64
0.85
0.67
0.97
1.35
5.76
3.45
1.69
1.18
1.05
0.57
0.72
0.68
0.88
1.36
4.45
5.27
1.68
1.27
1.55
Pb
0.86
0.93
0.63
0.82
1.74
0.78
0.66
0.53
0.20
0.24
0.94
1.06
0.76
0.79
1.98
0.69
0.57
0.69
0.20
0.20
0.91
0.91
0.62
0.77
1.94
0.50
0.50
0.59
0.22
0.23
Zn
67.5
79.5
80.0
88.8
125.5
66.0
50.0
54.0
47.0
39.8
68.7
79.0
79.5
132.
152
57.5
49.0
59.5
46.5
47.8
65.5
91.0
105.5
172.5
167.0
66.0
47.5
65.8
57.5
60.3
236
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5.4 Public Relations
Public relations and education are critical to the success of the MMSD's Metrogro program. The
MMSD has sought to include the public in the planning and design of the Metrogro system.
Questionnaires were distributed to farmers to determine their interests, concerns, and farming
practices. Equipment demonstrations were held, and feedback was sought from farmers, local
officials, and the public. Farmers were interested in having equipment that would incorporate
residuals into the soil, and they preferred high flotation tires that would help reduce soil
compaction. Local officials were concerned about road damage from heavy truck traffic. The
cleanliness of the applications was of concern to both homeowners and farmers.
One of the first steps taken in the Metrogro public education effort was to avoid the use of the
term "sewage sludge" because of its negative connotations. A contest was held to select an
alternative term. The reus ogram became known as the "Metrogro Program" and the biosolids
were referred to as "Metrogro". A logo was developed to help identify the "Metrogro Program".
The MMSD attends town meetings and sponsors farmer meetings to explain the benefits and
limitations of the environmental monitoring program, the wastewater treatment processes, and the
land application program. Tours of the treatment plant are given to interested parties. Public
demonstration plots comparing Metrogro and commercial fertilizer treatments were established
and maintained.
The local news media are kept informed about the project and its activities. The relationship with
the media continues to be favorable. Articles in local newspapers and farm publications generally
promote the Metrogro program.
The perception that Metrogro is a resource rather than a waste product was fostered by
establishing a fee for the biosolids application. Over the years increases in the fees have been
made. The fee is currently $7.50 per acre. The fertilizer N-P2O5-K2O value of the biosolids is
237
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around $35 in fertilizer savings. This value was calculated for 64, 120, and 14 pounds of N,
P2O5, and K2O/ton using $0.20, $0,23, and $0.12 for N, P2O5, and K2O respectively.
Other activities and publications the MMSD has developed to educate the public and farm
community include the following:
+ Informational brochures.
$ Letters to farmers once or twice a year,
* A slide show for public meetings and school demonstrations.
4 Periodic farmer meetings.
The private groundwater testing program has also become a part of the outreach program. A
representative of the treatment plant contacts the landowners on a regular basis. Complaints and
concerns about the program are likely to be discussed with the representative and can be dealt
with in a constructive manner.
Farmer acceptance of the Metrogro program seems to rest on the following factors:
$ Keeping the application equipment clean and neat to project a professional image.
$ Trying to minimize the compaction of soil by keeping the staging area in the field
as small as possible.
$ Using a storage tank in the field to provide a buffer between the trucking and
application of biosolids, increasing the efficiency of the operation.
$ Employing experienced operators, who can minimize mistakes during the land
application.
4 Being willing to do a little extra work to leave the field in a condition that helps
the farmer with his operation.
$ Maintaining a constant presence in the community, so that the program is
associated with the activities of the city, like garbage pickup or street cleaning.
238
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5.5 Summary
The MMSD has been applying biosolids from its Nine Springs WWTP on privately owned
farmland since 1974. The Nine Springs WWTP produces approximately 20 dry tons of biosolids
per day. An existing lagoon storage system allows the MMSD to store biosolids during periods
when inclement weather and agricultural practices prevent land application. New storage tanks
are being constructed, and a portion of the existing lagoons is being closed. The new tank
facilities should provide storage capacity for 180 days of biosolids production at maximum
monthly flows.
Anaerobically digested biosolids are thickened to approximately 6 percent prior to land
application. The MMSD uses its own equipment to transport and apply biosolids on a regular
basis; however, contractors are used to supplement the MMSD's operations during peak periods.
Biosolids are injected at agronomic rates that typically range from 3 to 5 dry tons per acre per
year. Total cumulative biosolids loading on the site evaluated is approximately 80 dry tons per
acre, equivalent to 16 to 27 years of consecutive agronomic applications.
One of the unique aspects of this program is the use of a storage tank in the field to decouple
the transport and application of biosolids. Using storage tanks in the field has increased the
MMSD's productivity by about 25%.
A comparison of soil metal loadings and soil metal test values show that the two parameters are
not well correlated. For example, lead concentrations in the surface soil increased faster than
would be expected from the loading.
Field experiments were conducted by the MMSD to evaluate plant uptake of metals. Under the
controlled conditions, significant increases in zinc and cadmium concentrations could be detected
in corn ear leaf tissue.
239
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The MMSD's groundwater monitoring program has shown a trend for increasing nitrate and
chloride concentrations over time. However, a study comparing the groundwater quality at
Metrogro sites to sites where commercial fertilizers and animal manures arc used showed that
the impacts from Metrogro applications appear to be no different than the impacts from
traditional farming practices.
The MMSD credits its extensive public relations efforts and willingness to work with farmers for
the success of the program. The public is not only regularly informed about the program's status
through the news media and public meetings, but the MMSD also involves the public in the
planning and design of the program. For example, the public was actively involved in the
selection of equipment and the Metrogro logo. The perception that biosolids are a resource rather
than a waste is fostered by charging a fee for the biosolids application.
240
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METRO WASTEWATER RECLAMATION DISTRICT, DENVER CO
Contact Person: William J. Martin
Metropolitan Denver Sewage Disposal Dist. No. 1
6450 York Street
Denver, CO 80229
Phone Number: (303) 289-5941
Average flow 150 mgd
Design capacity 185 mgd
Dry tons of biosolids/day 70
Type of biosolids anaerobically digested
Biosolids management options land application and composting
Application method injection/surface application followed by incorporation
Started application 1979
6.1 Program Overview
The Metro Wastewater Reclamation District (MWRD) began processing wastewater at the Central
Plant in 1966. The agricultural land application program was established in 1979. The MWRD
currently processes 150 mgd at its Central Plant, which has a design capacity of 185 mgd. The
plant provides primary and secondary treatment using the activated sludge process to provide
nitrification-denitrification. Primary and secondary sludges are combined and stabilized by
anaerobic digestion. The treatment plant produces about 70 dry tons per day of digested
biosolids. The digested biosolids are thickened or dewatered using centrifuges. The dewatered
biosolids are either applied to agricultural land or composted and sold to the public under the
name METROGRO™. The charges for the METROGRO™ products at the time of this study
are:
241
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4 $1.75 per 1.25 cubic foot bag of fine-screened compost.
4 $19.00 per ton for fine-screened compost.
4 $13.00 per ton for coarse-screened compost.
4 $3.00 per acre for thickened or dewatered biosolids.
About 10% of the biosolids produced is currently composted, and the remaining 90% is applied
to land. While composting is more expensive than land application, the MWRD maintains the
composting facilities to enhance the flexibility and reliability of the program. During the
preparation of this report, the MWRD purchased approximately 10,000 acres of land. Use of this
site will reduce the need to obtain permits from local jurisdictions for privately-owned farmland
and allow MWRD to manage the entire agricultural program.
The MWRD began applying biosolids to privately-owned farmland in 1979. The biosolids are
thickened to approximately 8 to 9 percent total solids prior to being transported to the application
site in 7,000-gallon tank trucks. The MWRD owns eight tank trucks like the one shown in
Figure 6-1. The biosolids are injected 6 to 12 inches beneath the soil surface by one of three
injection vehicles. Two of the injection units have a capacity of 7,200 gallons and the third one,
4,000 gallons.
Later, the MWRD began surface application of dewatered biosolids to improve the cost-
effectiveness and flexibility of the program. Dewatered biosolids can be applied during the
winter months when subsurface injection is impossible. The dewatered biosolids are transported
to the application site in 45 cubic yard tractor/trailer trucks and discharged into a temporary
holding area at the application site. The holding area is a three sided earthen pit (similar to a
bunker silage pit), that will be restored when the application has been completed. A front-end-
loader is used to load the biosolids into one of three 22-cubic yard, custom-built surface
spreaders. The biosolids are usually not stockpiled overnight at the application site because of
the odor potential. However, if they must remain in the loading pit overnight, soil is used to
cover the biosolids.
242
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Figure 6-1. Biosolids tanker truck.
243
-------
Spreaders were custom built to provide a more even application of biosolids than commercially
available spreaders. The MWRD's spreaders have a metering screw and gauge that allow the
operator to obtain a more even application than could be obtained with commercial equipment
and the MWRD's biosolids. In addition, the MWRD installed a heating system on the spreader
box, which allows for spreading of biosolids during the winter months.
Following surface application, the solids are incorporated into the soil by disking and plowing,
as shown in Figure 6-2. The MWRD supplies the labor and tillage equipment. In some cases,
minimum tillage (para-tilling) is required by the U.S. Department of Agriculture Soil
Conservation Service (SCS) to minimize erosion potential. The Agriculture Stabilization and
Conservation Service (ASCS) and SCS are also beginning, through contingencies on farm
subsidies, to encourage certain tillage practices. To facilitate application during the winter,
sufficient land is prepared to allow application of 90 days' biosolids production. Construction
plows pulled by a tracked tractor are used to incorporate the biosolids during the winter.
Although the MWRD prefers to surface apply dewatered biosolids, it continues to use subsurface
injection on sites in developed areas to avoid odor complaints.
Biosolids application rates are based on the recommended nitrogen loadings for the intended crop,
and the plant available metal concentration in the soil. The most common crops grown on
biosolids-amended soils are dryland wheat and irrigated corn. In 1992, the MWRD had permits
for approximately 18,000 acres of dryland wheat, and 5,000 acres of irrigated corn land. Average
winter wheat yields have increased from 40 bushels per acre without biosolids to 65 bushels per
acre after biosolids application. Corn is grown for both silage and grain. Annual application
rates range from 1 to 3 dry tons per acre (50 to 75 pounds of nitrogen per acre) for dryland
wheat, and from 5 to 10 dry tons per acre (about 300 pounds of nitrogen per acre) for corn.
Based on these rates, biosolids are applied to 1,900 to 19,000 acres annually. The exact acreage
depends on the mix between dryland and irrigated fields used. Other crops that have been grown
on biosolids-amended soils include milo, oats and barley.
244
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. -„-•-% 7 . .^--;?*r?T :^:* •'•*•
-*
Figure 6-2. A field after biosolids application and incorpor-
ation.
245
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The MWRD had approximately 150 permitted sites at the time of this study. Transport distances
vary widely from approximately 30 miles to as much as 150 miles one-way. Of the 150 sites,
24 are at least 90 miles away. One of the primary reasons for the long transport distances is the
difficulty in obtaining permits from local jurisdictions.
In selecting application sites, the MWRD follows the criteria established by the Colorado
Department of Health. In addition to the state permits, the MWRD is required to obtain county
permits for sites in Adams and Wells Counties. More than 50 percent of the MWRD's permitted
sites are located within Adams County. Approval of a site in Adams County is contingent on
SCS approval. A number of sites used in the past have been denied renewed permits because
the SCS had concerns about the suitability of sandy soils for application. The primary concern
is that sandy soils could pose an increased risk for leaching of nitrate and other constituents.
Permitting fees are charged by the state and the county. The state currently charges $2.40 per
dry ton of biosolids applied, while the County fees are approximately $0.50 per dry ton. In
addition to the permit fees, local jurisdictions often require a 24 to 48-hour notice before
biosolids can be applied to specific sites.
6.2 Monitoring
Soil samples are taken from each site prior to the application of biosolids and tested for nutrients
using Colorado State University tests. Both total and extractable metal concentrations are
determined. DTPA extraction is used to measure available metals in the soil. Soil samples are
stored for one year. Crop samples are collected at harvest. Biosolids are sampled from the
loading area during the land application. The District works with the U.S. Geological Survey
(USGS) to monitor the groundwater at a selected site, which is assumed to be representative of
all of the application sites. The parameters monitored are summarized in Table 6-1.
246
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Table 6-1
Parameters Monitored by Metro Wastewater Reclamation District
Parameter
pH
Electrical Conductivity (EC)
Cation Exchange Capacity (CEC)
Organic Matter (OM)
Total Volatile Solids
Total Kjeldahl Nitrogen (TKN)
Nitrate-Nitrogen (NO3-N)
Ammonium-Nitrogen
Phosphorus
Available Phosphorus
Potassium
Available Potassium
Aluminum
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Iron
Lead
Mercury
Manganese
Molybdenum
Nickel
Selenium
Silver
Zinc
Available Cadmium
Available Copper
Available Iron
Available Lead
Available Nickel
Available Zinc
Polychlorinated Biphenyls (PCB)
Asbestos
Fecal Coliforms
Soil
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Biosolids Crops
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
Groundwater
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
247
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6.3 Results
Table 6-2 shows the composition of the thickened digested biosolids. The concentrations of
most metals and nutrients have been fairly constant during the past 10 years. Lead concentrations
show a downward trend over the last decade, while zinc, nickel, and cadmium remain unchanged
as shown in Figure 6-3. The biosolids have concentrations less than the Pollutant Concentration
limits of the 40 CFR Part 503 regulations for all elements except molybdenum; but the
molybdenum concentration is well below the Ceiling Concentration of 75 mg/kg.
Table 6-3 and Table 6-4 show the soil analysis from two sandy loam fields. Field 88 had
received 53 dry tons of biosolids per acre over an 8-year period, while Field 89 had received 42
dry tons per acre. Tables 6-5 and 6-6 show the amount of biosolids and the concurrent metal
loadings applied to these two fields.
The usable site-life of these fields is going to be limited by zinc or copper. On the sites
examined, the concentration of organic matter has doubled since the biosolids application began.
This should enable farmers to reduce the application of water to amended fields, although no
water use data are available to verify this. The increase in organic matter might account for the
higher yields on the biosolids-amended soils.
The total and available phosphorus levels in the soils at Fields 88 and 89 increased significantly
during the study period, as shown on Tables 6-3 and 6-4. For example, on Field 88 the total
phosphorus level increased from 210 to 505 mg/kg, and the available phosphorus level increased
from 19 to 100 mg/kg. This increase is in response to the application of about 2,900 pounds per
acre phosphorus over a 10 year period. Only about one-fifth of the applied phosphorus can be
detected in the soil, but a TKN digestion is used to determine total phosphorus content. This type
of digestion does not solubilize all of the phosphorus in the system.
248
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Table 6-2
Average Concentrations in the Metro Wastewater Reclamation District
Digested Biosolids
Parameter
PH
EC («raho/cm)
OM
TKN
NH4-N
NOj-N
Phosphorus
Potassium
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Zinc
PCB
1983
7.4
6,980
N/Af
8.33
2.83
0.08
2.35
0.49
6,950
0.09
24.9
276
675
30,400
344
9.9
18
98
<0.01
110
1,500
N/A
1984
7.3
12,600
N/A
8.28
4.48
0.02
3.13
0.50
9,080
1.55
28.0
N/A
826
18,000
445
10.5
67
124
0.09
N/A
1,500
<1.0
1985
7.7
4,130
N/A
7.5
2.24
<0.01
2.7
0.42
20,000
0.29
18.0
212
670
19,900
270
5.2
36
76
<0.08
92
1,400
<1.0
1986
8.0
9,960
32
7.0
3.00
0.01
2.12
0.30
6,890
3.0
12.1
123
535
14,900
203
3.0
8.5
69
3
53
1,220
<1.0
1987
7.8
6,900
N/A
4.9
1.08
<0.01
3.4
N/A
7,350
4.2
7.2
86.9
1,130
18,200
189
4.1
10
135
5.1
57
1,040
<1.0
1988
7.4
6,900
or..
N/A
6.2
2.38
<0.0l
2.35
0.30
n.
nig/kg - — •
11,000
0.0
9.1
137
566
18,200
180
3.8
19
64
10
115
1,130
<1.0
1989
7.8
15,300
62.1
9.4
2.87
<0.01
2.23
0.33
10,900
9.2
9.5
165
829
31,000
210
4.2
28.3
114
3.3
86
1,450
<1.0
1990
7.8
15.300
64.1
9.5
2.87
<0.01
2.23
0.33
10,900
9.2
9.5
165
829
31,000
210
4.2
28.3
114
3.3
86
1,450
<1.0
1991
7.8
15,300
64.1
9.5
2.87
<0.01
Z23
0.33
10,900
9.2
9.5
165
829
31,000
210
4.2
28.3
114
3.3
86
1,450
<1.0
1992
7.9
11,800
67.7
7.7
3.13
0.01
2.32
0.39
8,920
6.0
12.0
114
622
26,600
165
3.0
30
54
7
95
1,010
<1.0
* Data not available.
249
-------
10,000
Cadmium
-*- Nickel
-*-Zinc
83 84 85 86 87 88 89 90 91 92
Year
Figure 6-3. Pollutant concentration trends (1983-1992).
250
-------
Table 6-3
Soil Analysis for Field 88
Parameter
PH
CEC (meq/lOOg)
OM (%)
EC Cumoh/cra)
1982
7.4
6.5
0.60
380
1983
7.8
6.1
0.60
329
1984
6.6
8.7
0.80
420
1985
6.5
9.4
0.83
295
1986
6.6
7.0
0.80
368
1987
6.6
7.0
1.01
568
1988
6.5
6.0
0.62
426
1989
7.7
14.6
1.28
520
1990
7.1
12.9
1.60
468
1992
7.0
13.8
1.24
516
Total Concentrations frac/ke}
Phosphorus
Cadmium
Copper
Iron
Lead
Nickel
Zinc
210
N/A
5.0
N/Af
N/A
N/A
27
210
0.08
3.5
6,500
7.5
4.0
24
290
0.20
8.5
10,600
10.0
8.0
42
325
1.32
4.8
6,920
13.9
4.4
27
446
1.40
9.4
8,380
20.0
6.8
40
490
0.80
9.0
20.0
5.9
44
610
0.30
6.7
7,960
20.0
5.3
38
560
0.20
9.0
10,200
40.0
7.8
55
580
0.20
10.0
9,760
24.0
6.1
56
505
0.49
7.0
7,770
27.0
4.2
47
Available Concentration fmeAg)
NO,-N
NH,-N
Phosphorus
Cadmium
Copper
Iron
Lead
Nickel
Zinc
7.4
N/A
19.0
0.05
0.52
N/A
0.94
0.26
1.2
14.2
N/A
28.2
0.08
0.86
16
0.94
0.24
1.5
8.9
N/A
57.2
0.12
2.78
24.8
1.6
0.64
3.98
4.0
N/A
50.8
0.15
2.77
30.6
1.18
0.92
4.34
3.8
N/A
59.8
0.16
3.49
30.2
1.32
0.59
5.39
23.0
3.6
81.0
0.17
4.92
35.8
1.31
0.9
6.91
6.3
2.2
67.0
0.74
4.02
37.2
1.4
0.66
5.18
19.5
3.0
108
N/A
N/A
N/A
N/A
N/A
N/A
20.0
4.7
101
N/A
N/A
N/A
N/A
N/A
N/A
9.6
2.9
52.4
N/A
N/A
N/A
N/A
N/A
N/A
' Data not available.
251
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Table 6-4
Soil Analysis for Field 89
Parameter
pH
CEC meq/lOOg
O.M. %
NOj-N rag/kg
NH.-N mg/kg
EC moh/cm
1982
6.5
12.6
0.43
10.4
N/A*
N/A
1983
7.4
8.3
0.82
1.2
N/A
N/A
1984
1986
7.0 6.5
7.4 6.7
0.62 0.73
11.6
N/A
N/A
4.6
N/A
N/A
1987
6.9
6.3
0.85
11.6
28.6
465
1988
6.5
5.0
0.57
2
2.2
197
1989
7.4
14.3
1.21
10.6
1
198
1990
7.4
6.1
0.63
Z4
1.38
224
1991
6.5
10.1
1.24
7.4
2.10
251
Total Concentrations (mg/kg)
P
Cd
Cu
Pb
Ni
Zn
Fe
230
N/A
7.6
N/A
N/A
42
N/A
330
0.2
6.5
6.2
5.8
34
8,000
310
0.2
12
12
6.5
42
9,250
567
1.93
6.7
20
5.8
33
6,970
400
0.5
7.0
20
5.3
31
6,320
620
0.6
6.2
17
4.8
31
490
1.5
12
27
9.3
56
6,790 10,915
340
0
3.0
10
ZO
20
7,030
486
0.5
15
22
4.7
47
8,760
Available Concentrations (mg/kg)
P
Cd
Cu
Pb
Ni
Zn
Fe
20
0.92
1.1
1.4
0.68
0.56
N/A
21
0.09
1.3
1.0
0.46
2.56
22
59
0.10
2.52
1.42
0.62
3.56
24
64
0.12
2.66
1.03
0.66
3.46
31
69
0.12
4.12
0.99
0.77
5.15
32
55
0.12
3.2
1.2
0.60
3.90
34
120
N/A
N/A
N/A
N/A
N/A
N/A
56
N/A
N/A
N/A
N/A
N/A
N/A
61
N/A
N/A
N/A
N/A
N/A
N/A
* Data not available.
252
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Table 6-5
Annual Loading to Field 88
Year
1983
1984
1985
1986
1987
1988
1989
1990
Total
Biosolids
9.0
6.4
6.0
8.4
7.3
11.5
5.2
4.6
58.4
Cd
0.38
0.26
0.21
0.21 /
0.13
0.23
0.08
0.08
1.5
Cu
13.7
8.02
7.07
9.86
2.66
12.7
5.61
4.4
64.0
Pb
5.94
3.65
3.24
3.59
0.96
4.13
1.63
1.43
24.6
Ni
1.88
1.16
0.69
1.13
0.44
1.65
0.74
0.39
8.08
Zn
25.6
18.2
15.6
19.9
6.9
24.6
10.8
8.7
130
P
421
401
323
356
496
551
195
181
2924
Table 6-6
Annual Loading to Field 89
Year
1983
1984
1986
1988
1990
Biosolids
9
5
7
18
7
Cd
0.38
0.24
0.19
0.43
0.13
Cu
15.8
5.32
8.23
17.3
6.99
Pb
7.42
2.56
3.21
6.05
2.28
Ni
1.81
0.85
1.19
2.27
0.63
Zn
28
11.7
16.7
36.5
13.9
P
381
275
242
201
290
Total
46
1.37
53.6
21.5
6.75
107
1,389
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With the exception of lead, only a relatively small portion of the added metals could be detected
in the soil. For the two fields studied, an average of 25 percent of the cadmium, 8.7 percent of
the copper, 81 percent of the lead, 2 percent of the nickel, and 11 percent of the zinc was found
in the soil. Metal concentrations in the corn tissue on Field 88, as shown in Table 6-7, are
variable. The concentrations are similar to those in diagnostic corn tissue grown on soils not
treated with biosolids.
The MWRD, jointly with the USGS, recently completed a five year groundwater monitoring
program. The site used in the study was selected because of its sandy soils and relatively
shallow depth to groundwater. The program was to determine whether the land application
practices resulted in contamination of the groundwater with nitrates. Elevated concentrations of
nitrates and higher specific conductance were observed beneath the site; however, the source of
the contamination could not be identified. The use of commercial fertilizers, animal manure, and
biosolids were all considered to be potential sources. Because of the inconclusive results of the
groundwater monitoring program, the MWRD is beginning a new groundwater monitoring
program at a controlled site where the MWRD will control not only the application of biosolids,
but also the agricultural management of the site.
Table 6-7
Metal Concentration in Corn Ear Leaf Tissue on Field 88
Year
1984
1986
1987
1988
1989
Cu
3.8
3.6
nd
4
2.6
Ni
10.2
0.2
5.3
2
nd
Zn
19
22
45
60
31
Pb
g/Kg -
<0.2
nd'
6.0
2
nd
Cd
<0.1
0.1
nd
nd
nd
TKN
13,000
13,800
16,300
13,000
12,000
f Parameter not detectable by the method of analysis.
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6.4 Public Relations
The MWRD strives to maintain positive relationships not only with the farmers providing the
land, but also with the general public. The MWRD works with the farmer to schedule biosolids
application and tilling operations to meet the farmer's needs and to ensure that the tillage method
complies with SCS requirements. Farmers are charged $3.00 per acre for the biosolids
application. The MWRD has estimated that the total value of this service to the farmer,
including the nutrients and tillage, is between $30 and $60 per acre. In addition, the MWRD
maintains the roads during application at the farm site.
MWRD personnel participate in public hearings, respond to citizen complaints, and assist with
the repair of roads damaged by the biosolids trucks. Some counties require a public hearing for
each permitted site. MWRD personnel respond to odor complaints by going to the source of the
complaint and taking scentometer readings. The readings are recorded, and any possible
mitigation measures are implemented. The number of complaints in recent years has not
exceeded four per year.
The METROGRO™ name was chosen for the biosolids and the composted biosolids to provide
a name free of the negative connotations associated with "sludge".
6.5 Summary
The land application program, which has been in operation since 1979, is the primary method
of biosolids utilization by the MWRD. While a portion of the biosolids produced are handled
through a composting and distribution program, land application remains the primary method
because of its cost-effectiveness. Recently, the MWRD has encountered difficulties in permitting
sites in nearby townships and counties and has been forced to transport biosolids to sites as far
as 150 miles away. The MWRD has recently purchased land for a biosolids application site
because of these problems.
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Biosolids are either injected or surface applied and incorporated in the soil. Typical application
rates are between 3 and 8 dry tons per acre. Cumulative biosolids applications after eight years
are currently between 30 and 60 dry tons per acre. Review of available biosolids quality data
shows that most metal and nutrient concentrations over the last eight years have remained
relatively constant. Cadmium, lead, and nickel concentrations have decreased, probably as a
result of industrial pretreatment.
Concentrations of extractable metals in the soil remained constant through the last 10 years. One
exception was lead, which showed a slightly increasing trend. Total and available phosphorus
increased, and the organic matter content of the sandy loam soil doubled. The increase in
organic matter could be expected to reduce the demand for irrigation water. Plant tissue data
showed no increase in the plant uptake of metals.
The results of past groundwater monitoring at the District's test site were inconclusive because
the District was unable to control the management of the privately-owned site. Although
elevated nitrate levels were observed, commercial fertilizers, animal manures, and biosolids were
all believed to have contributed to the contamination.
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FERTILIZING FORESTS WITH BIOSOLIDS:
HOW TO PLAN, OPERATE, AND MAINTAIN A LONG-TERM PROGRAM
Peggy Leonard
Forestland Coordinator
Roberta King
Research and Monitoring Coordinator
Mark Lucas
Senior Land Reclamation Coordinator
Sludge Management Program
Municipality of Metropolitan Seattle
821 Second Avenue, Mail Stop 81
Seattle, WA 98104
INTRODUCTION/PROGRAM HISTORY
The Municipality of Metropolitan Seattle (Metro) has a program of beneficial use of its biosolids in
composting, agriculture and forest fertilization projects. Metro's land application program began in
the early 1970s, with a proposal from the University of Washington to study the potential benefits of
wastewater sludge as a fertilizer of commercial forests of the Puget Sound area. The first ten years of
research by the University focused on application technology, environmental effects, and growth
response. After determining that sludge greatly increased tree growth on nutrient-poor soils and
could be applied safely with no detrimental public health or environmental effects, the University and
Metro moved on to larger-scale demonstrations.
In 1985, Metro conducted operational-scale applications on some of its own forestland in the county.
After that, two timber-growing companies and the state department of natural resources signed
agreements with Metro for applications on their own lands. The most suitable sites for sludge
application, both from a technical and public access standpoint, were found on one of the companies'
lands. Metro staff concentrated their efforts on developing a project with that landowner, the
Weyerhaeuser Company.
Metro is now in its sixth year of operations on Weyerhaeuser lands with over 19,000 dry tons of
biosolids applied. The program has been'Successful for both biosolids generator and landowner, but,
as with any ongoing program, has had its share of the unexpected. As Metro now begins working
with farmers in agricultural uses of biosolids, we are using many of the "lessons learned" from
forestry in how to work with the landowner and the public, and how to manage operations and
maintain quality control.
In this paper, the authors will describe how Metro has developed its program with this landowner,
how application sites are designed and operated, and the standards of performance that we feel are
necessary for successful long-term operations.
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WHY FOREST APPLICATION?
Technical Reasons
(1) The soils need nitrogen and organic matter.
The soils in the Puget Sound area are glacially derived, composed of deep layers of gravel and sand
deposited by glaciers that moved into Washington from the north. They are young on a geological
timescale, and so lack the reserves of organic matter and minerals found in older, more developed
soils. Forest soils of the entire region are generally deficient in nitrogen.
(2) Forest fertilization with nitrogen is a well-known industrial practice.
Some of the large industrial landowners have established programs of fertilizing both natural stands
and plantations with chemical nitrogen fertilizer in the form of urea. Thus, the concept of routine
fertilizing to produce faster growth in trees is not new in the Northwest.
(3) The most important commercial tree species grows faster with biosolids.
Early research with a variety of Northwest tree species demonstrated that Douglas-fir trees had the
best growth response to sludge. Douglas-fir is the most important commercial tree in the Pacific
Northwest. Most private timberland owners in our region grow Douglas-fir on a cycle of 45 to 50
years, replanting and managing it in single-species plantations. Since the 1960s, Douglas-fir has been
fertilized with nitrogen. But research showed that growth response to biosolids exceeded the
response from urea.
(4) The climate and terrain near Seattle allow nearly year-round operations.
The maritime climate is characterized by mild, wet winters and cool, dry summers. In the lowland
forests east of the city, precipitation averages about 60 inches per year, with average daily
temperatures of 40 degrees in the winter and 60 degrees in the summer. Light snow may occur
December through February, with accumulations averaging less than 6 inches. The gravelly forest
soils are well-drained and can withstand the impact of ground equipment, even during the wet
winters.
Location and Land Use/Ownership Patterns
Other cities may find, like Seattle, that if large tracts of foresdand are close to the city, they are a
logical and feasible choice for biosolids management.
The population centers of western Washington are located along Puget Sound. East of the cities is the
broad, rolling to level plain occupied by commercial forests and rural communities, but with
encroaching suburban development. Further east, about 75 miles from Seattle, are the foothills and
mountains of the Cascade Range. Most of the state's agricultural areas (grains and fruit) are located
over the mountain passes on the eastern side of the Cascades, where the climate is much drier.
Several forest products companies have large timber holdings in the glacial plains immediately east
and within 30 miles of the Puget Sound cities (Seattle, Tacoma, Oiympia). Although these forests are
open to the public for hunting, they are "Working" forests with a great deal of harvesting activity and
log truck traffic. These large contiguous tracts have a well developed network of gravel roads and
access that is controlled through a few main gates. These characteristics, plus the remoteness from
residences, make these areas well suited for use of biosolids.
Transportation Cost
The close-in location reduces the cost of hauling biosolids from the treatment plants. Metro's hauling
costs are from $9 to $10 per wet ton (23% solids) for forest sites, while agricultural sites are generally
about 200 miles from the treatment plants and average $25 per ton for hauling. As seen in Figure 1,
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however, total haul and application costs for the two uses are comparable due to the ease of
application in agricultural fields.
OPERATIONS ON THE SNOQUALMDE TREE FARM
In 1985, Metro and the Weyerhaeuser Company signed a 2-year agreement for the utilization of
Metro's biosolids — trademarked Silvigrow — on the company's Snoqualmie Tree Farm,
approximately 30 miles east of Seattle. The tree farm encompasses 170,000 acres, most of it in one
large contiguous block. The application of Silvigrow to selected areas would supplement the
company's urea fertilization program. The first Silvigrow project, 160 acres of 5-year-old trees, was
begun and successfully completed in 1987. After two years of projects, the agreement was renewed
for another two years and then in early 1991, a ten-year agreement was signed.
Metro has the responsibility for site selection, design, permitting, operation and monitoring. Site
design and operating plans are subject to company approval, particularly with respect to haul and
transfer routes within the private road system of the tree farm. Weyerhaeuser retains the responsi-
bility for managing the timber to meet its corporate objectives. What follows is a discussion of how
Metro plans and operates its fertilization projects on this tree farm.
Site Selection
Careful site selection is essential for producing the best growth response. Listed below are the most
important factors that we consider when choosing candidate sites. Initial screening is done in Metro's
office with topographic maps, soil maps, recent aerial photos and the landowner's inventory records.
A careful walk-through of each potential site is necessary to confirm the suitability of the soils and
terrain. See Figure 2 for the checklist that we develop for each site that is inspected in the field.
• Terrain - gentle
For ground application, equipment is limited to slopes of 30%, and ideally, slopes of 15% or less.
Federal and state guidelines recommend rolling to level sites, with only short stretches of slopes at
30%. We've found that sites with a slight tilt or those with some variable topography are preferable
to those "flat-as-a-pancake" sites, where drainage problems can develop.
Slope allowances for forestry sites are considerably higher than those allowed in agriculture. This is
due to the excellent infiltration capacity of the forest floor and, in young stands, the amount of herbs
and shrubs in the understory whose foliage intercepts the biosolids and aids in stabilizing and drying.
• Soils - well drained
We target soils that have a high content of gravel and sand and minimal amounts of clay. These soils
work best for two reasons: (1) they can withstand the impact of the loaded applicator vehicles, even
during wet winter weather. To apply a full prescription of biosolids usually requires many passes. If
the soils are too fine-textured, the applicator vehicles can create deep ruts and mud. In our
experience, trail rutting is one of the "hot buttons" for the timberland owner. The owner wishes to
preserve and enhance the long-term productivity of his lands, and rutting destroys the fertile upper
horizons of the soil. (2) coarse textured soils are low in nutrients and need extra nitrogen and organic
matter. The best growth response to biosolids are on sites of this medium to poor quality.
• Vegetation - well stocked and the right height
Height of the trees is a critical factor. Early research by the University of Washington demonstrated
that when biosolids is applied to very young plantations, there are several undesirable results: (1) if
not controlled by herbicides, understory plants will respond rapidly and compete with the tree
seedlings for water, nutrients, and light; (2) the heavy herbaceous growth leads to population growth
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of small rodents who will chew on and girdle the tree seedlings; (3) the amount of damage to the
seedlings from browsing deer increases, as the deer will preferentially browse on fertilized seedlings
that are at or below their "browse height" of 4 to 5 feet. To avoid these problems, we apply only to
plantations that are at least five feet tall and that have a minimum of brushy, unstocked "holes" in the
plantation.
• Surface waters - as few as possible
Sites with many draws, streams and wetlands may require a large proportion of the area in setbacks or
buffers, thus reducing the net usable area for application. Generally, sites with well drained soils will
have 30% or less of the area lost to buffers.
• Road system - suitable width and grade
Although the tree farm includes plateau, foothills, and mountainous areas from 700 to over 3500 feet
in elevation, our operations are limited to the lower elevations by the inability of the biosolids
delivery trucks to haul steep grades on gravel roads. Grades cannot exceed 10% for long distances
and the roads must have frequent turnouts or be wide enough to allow two trucks to pass each other.
• Seasonal restrictions - no slurry on the foliage in dry season
Liquid or rewatered Silvigrow at 7 to 15% solids cannot be applied over the foliage of trees during
the growing season, since the summers in the Pacific Northwest are relatively dry. There is no rain to
wash the foliage, and the biosolids become cemented onto the foliage. (Metro is currently testing
equipment that applies biosolids as dewatered cake. This type of application may minimize the
amount of biosolids clinging to the foliage and so may be suitable for summer use. More on this later
in the paper.)
• Project size
The minimum parcel size that allows continuous operations is dependent upon the time required for a
layer or lift of Silvigrow to stabilize. A typical rate of 10 DT/ac is applied in three separate lifts with
drying time after each application. During the wet season, a lift requires three to four weeks to
stabilize. If Silvigrow can be applied at the rate of 40 acres per week, then 160 acres of working area
is required to keep operations continuous for 4 weeks. By that time the first areas to be applied would
be stabilized and ready for the second lift. The entire 160 acres would be completed in 12 weeks.
Design Factors
The first steps in confirming the initial assessment of a site are a soil evaluation and an assessment of
the ground water conditions. These tasks are performed by University soil scientists and
hydrogeology consultants, respectively. See Figure 3 for the sequence of steps in designing and
permitting a site.
To design each project, Metro employs contract foresters who are knowledgeable in the best
management practices of biosolids application. During a thorough examination of each proposed
unit, they eliminate areas that are too steep, too wet or that might be pathways for water movement
during rainstorms. Boundaries of the usable area are marked in the field with fluorescent pink
flagging. Then they design a trail system of parallel, looping or dead ended trails which will allow
the applicator vehicle to completely reach all the usable areas. We achieve slightly overlapping, even
coverage by applying into a compartment from trails on either side. The spacing between trails varies
from 185 to 200 feet, depending on the height and density of the trees. See Figure 4 for an example
of a trail system that covers a 98-acre site.
Streams in or adjacent to the application area are buffered by non-application strips of varying widths.
We use the following guidelines: 200 feet from large, continuously flowing streams, 100 feet from
small tributary streams, and 50 feet from ephemeral drainage ways. The purpose of the buffer is to
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provide a safety margin if an operator were to overshoot the boundaries or if Silvigrow were to move
during a rainstorm. The width of these buffers is far greater than actually needed. Since beginning
operations on this tree farm, we have had no significant movement of Silvigrow away from an
application area, primarily for two reasons: sites are heavily covered with vegetation, and the
practice of applying in thin layers works well to stabilize the Silvigrow.
The development of an appropriate application rate is an essential part of the design process.
Researchers from the University of Washington inspect all proposed forest sites and recommend an
agronomic rate. The variables in this calculation are: estimated annual uptake of nitrogen for tree and
understory species, mineralization rate for the organic nitrogen in the biosolids, soil storage capacity,
and estimates for volatilization and denitrification. With the total nitrogen in our biosolids averaging
about 5%, a typical application rate for a 10-year-old plantation is around 9 dry tons per acre. Our
current plans are for a 4 to 5-year cycle of reapplication.
Because Metro's biosolids are treated by a PSRP (Process to Significantly Reduce Pathogens) rather
than a PFRP (Process to Further Reduce Pathogens), site access is restricted for 12 months after
application. Yellow plastic signs are posted around the site boundaries every 100 to 200 feet:
Municipality of Metropolitan Seattle
& Weyerhaeuser Company
SILVIGROW APPLICATION BOUNDARY
Trees in this area are being fertilized with Silvigrow - biosolids from
Metro wastewater treatment plants. Any health risk to humans is
from eating soil during the first year after Silvigrow application.
Therefore, federal regulations restrict public access for one year.
Access Limited Until
For morv infortnition, call Metro Witor Ouality Communications
91684.1138. .
-tm A
Permitting Process
In the state of Washington, the state Department of Ecology has delegated permitting authority for
biosolids to local health districts. For this particular project, the Seattle-King County Department of
Public Health is the regulator and permitting authority. We are fortunate to have local regulators who
are knowledgeable about biosolids practices and research as well as the draft federal regulations.
Permitting of new areas on the tree farm has gone smoothly because of the projects' remoteness, low
public profile, and good monitoring results.
Following the submission of the permit application package (which includes description of soil
profiles, analyses of soils for metals and nutrients, chemical analyses of biosolids, topographic maps
of application areas, hydrogeology study, monitoring plan, calculation of application rates, and
proposed trail layout), the regulator makes a field visit with the project manager and field designer for
the project. Representatives from the state Department of Ecology attend whenever possible. The
field inspection usually focuses on the buffering and protection of water bodies and other sensitive
areas as well as any downstream water users. The entire permitting process can usually be completed
in 45 days, the minimum review period required by county regulations.
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Operations Tracking
Metro's current forest operations involve the addition of water to dewatered cake biosolids to produce
a slurry of 7 to 15% solids which is then sprayed onto the trees. The mixing/delivery station at the
tree farm is located in a large gravel pit. Here the haul trucks unload biosolids (at 18 to 27% solids)
into an in-ground mixing tank to which dilution water is added. The diluted biosolids, called
Silvigrow, are then pumped into adjacent storage tanks for the day's application. Usually 4 to 5
truckloads of 30 wet tons each can be processed and applied in a day.
The application units are usually located in a 3-mile radius from the mix station, so transfer tanker
trucks are used to shuttle Silvigrow from the mix station out to the working applicator vehicles. The
applicator vehicle is a rubber-tired, articulated, four-wheel drive chassis with a 2200-gallon tank
mounted over the rear axle. The tanks contain an internal pumping system driven by the power take-
off connected to a one-inch diameter nozzle mounted on top of the vehicle. The loaded applicator
vehicles travel into the forest on the trail system; they are stationary as the operator applies the
material, controlling the direction and trajectory of the spray from a joystick inside the vehicle cab.
Each operator has a clipboard with a map of the application unit and a logbook (see Figure 5). Each
application unit is divided into compartments of 1 to 6 acres which are used to keep track of the
actual amount of Silvigrow applied. For example the application rate for Unit 24-08-02 is 8.5
DT/acre. Compartment 22 in this unit is 1.1 acres, which would require 1.1 X 8.5 = 9.3 DT to
complete. Each applicator applies 1 DT per load, so 9 loads total would be needed for this
compartment. Applying this amount in three separate lifts means that 1 complete lift consists of 3
loads. The logbook is marked to show when each lift is completed.
At the end of each day, the site supervisor checks the condition of trails and the buffers for all the
compartments that were applied that day. Records of these checks (see Figure 6) are kept at the field
trailer at the mixing station for the Metro site manager's inspection.
Contingency Plans
Metro and the application contractor have developed a set of procedures for responding to any
incidents on the site. An "incident" may be a spill, surface runoff, traffic accident, work site accident,
misapplication of biosolids or any other site problem. The operations plan includes a contingency
plan, which outlines the individuals to be contacted in case of a large-scale incident. The plan also
includes a list of local contractors and their equipment (dump trucks, loaders, vacuum trucks, tow
trucks, and cranes) that could be called for assistance. Small spills or misapplications are corrected
immediately, and an Incident Report form (developed by Metro) is filed. We have had some trucking
incidents but no large spills in the 6 years of operation.
Monitoring
Water Quality - To evaluate the water quality of streams near Silvigrow sites, Metro establishes test
sampling stations downstream from project areas and control stations upstream. Two types of
monitoring are conducted: (1) Routine or ambient - conducted on a quarterly basis before, during,
and for three years following applications; and (2) Storm - occurs during two to three rainstorms in
the wet season following application. Storm sampling is conducted to ensure that Silvigrow is not
being carried offsite by surface runoff. All samples are grab samples, collected by water quality
specialists with Metro's Environmental Laboratories. Samples are analyzed for ammonia nitrogen,
nitrate-nitrite nitrogen, fecal coliforms, and enterococcus. Six years of sampling have shown little to
no significant changes in the excellent water quality in these streams.
There are no drinking water wells within a mile of any site, and most of the sites do not overlie
aquifers of any significant size. For these reasons, we do not use ground water wells in our
monitoring program. Two of our sites, however, have installations of tube lysimeters. Nitrate data
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collected from the lysimeters is used by the University of Washington to fine-tune their model and
assumptions of nitrogen uptake in Douglas-fir stands.
Tree Growth - Many of the application areas at the tree farm contain growth plots. To maintain
consistency in data collection, all growth plots are installed and measured by field crews from the
Stand Management Cooperative (SMC). (The SMC is a cooperative of universities and landowners
that sponsors integrated research in forest nutrition, silviculture, and wood quality.) Not all areas
have these plots; we install them whenever there is an opportunity to gather data from different soil
types or age classes of timber. The standard installation consists of three tenth-acre square plots
treated with biosolids and three control (no biosolids) plots in the same stand. All trees are numbered
and tagged; height and diameter are measured annually. Results from the first three years of
operations in young stands indicate increases in annual height increment can range from 20 to 75%
over controls.
Partnership with the University
Metro has continued its contract relationship with the University of Washington College of Forest
Resources since 1973, not only for research but for design assistance on operational sites. As
described in previous sections of this paper, researchers from the U.W. are an essential part of site
design. They make a field visit to each proposed application area to evaluate the suitability of the soil
to receive biosolids and to sustain traffic. They estimate the nutrient needs of the site and prescribe
the appropriate application rate. They propose research to fill in the knowledge gaps, monitor the
growth response, and assist us when something goes wrong. We know that their role is one of the
critical factors in the long term success of this project.
Other municipalities have developed this kind of partnership with research institutions. Some
examples are Greater Vancouver Regional District with the University of British Columbia, City of
Spokane with Washington State University, Massachusetts Water Resources Authority with the
University of Massachusetts, and Vail, Colorado with Colorado State University.
Performance Standards
Many of the operating practices that have been developed over the past six years of operations at the
Snoqualmie Tree Farm have been formalized and incorporated into a set of standards that is now
applied to all other kinds of biosolids projects. In any given month, Metro may deliver biosolids to
two or three kinds of projects. Each site may be operated by a different contractor, and even
permitted by different counties. Last year when one of the contractor-managed soil improvement
sites came under public scrutiny for failing to closely follow the operations plan, the sludge program
staff developed common performance standards to which all projects would conform. These
standards would ensure that all projects receiving Metro biosolids would operate with the same
attention to detail, regardless of the local requirements. The new standards gave Metro a visible and
active role during the permitting and operating of the project. Listed below are some of the key
requirements that have worked well on forestry sites and are now required of all other projects as
well:
• Operations plan with detailed site maps;
• Haul route approved by Metro;
• Agronomic application rates reviewed by university or other independent specialists;
• Buffers and boundaries clearly marked in the field;
• Good housekeeping measures at the site with daily inspections of boundaries and buffers;
.• Pre- and post-application monitoring of soils, surface water, and, if appropriate, ground water and
crops.
• Public information plan with early and ongoing public involvement opportunities;
• Contingency plan for any incidents;
• Quarterly and annual reports to be produced and available for any interested parties.
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WHEN SOMETHING GOES WRONG
Despite careful planning and site management, Murphy sometimes visits our projects. For the first
two years the Metro/Weyerhaeuser projects went smoothly; a total of 1200 acres had been permitted
and completed. Then scattered trees began to yellow and droop on one of the fertilized areas.
Scientists from the University of Washington College of Forest Resources began an investigation into
the source of the problem, which was obviously related to the biosolids application as adjacent
unfertilized areas were unaffected. Over the next few months, the clumps of dying trees totaled about
40 acres.
The research team concluded that the trees weakened because of inadequate soil aeration. This lack
of oxygen was caused by a combination of site conditions and the slow drying characteristics of
secondary biosolids under these conditions. The very flat terrain and shallow soils restricted winter
drainage, while the dense tree canopy kept the ground cool and shaded so that the biosolids did not
dry. Under these conditions, the biosolids sealed the soil surface, reducing the movement of oxygen
into the soil.
Weyerhaeuser forest scientists were consulted and involved in the investigation at every step, so there
was consensus among Metro, the University and the landowner that we had a developed a problem
that could be easily avoided in the future by focusing on young, open stands. The affected areas were
harvested prematurely and Metro paid Weyerhaeuser for the value of the lost growth. Applications
resumed the next year and are continuing.
CRITERIA FOR SUCCESS
• Find your niche in the landowner's overall management plan.
Niche, from the science of plant ecology, is defined as "the ultimate unit of the habitat, i.e. the
specific spot occupied by an individual; the more or less specialized relationship existing between an
individual and its environment." Forest landowners in Washington state have a multitude of laws,
restrictions and regulatory agencies to deal with. We want the use of biosolids to be an easy practice
to implement on their tree farm and one that requires minimal investment of staff time for them.
Metro staff handle all the site development and permitting for Silvigrow projects and work hard to
minimize any "hassle factor" for the landowner.
We also have found a place in the landowner's current management regime. Weyerhaeuser presently
begins urea fertilization around age 17 and continues on 7 year intervals through the entire rotation of
45 to 50 years. Silvigrow fertilization begins around age 5 and is reapplied on 5 year intervals. This
provides a real boost to developing plantations and allows the trees on these poorer-quality sites to
grow at a rate typical of much more productive sites.
• Hold your projects to the highest standards. There are many obvious reasons to run a clean, well-
managed operation. But it's essential if you're counting on a long-term relationship with a particular
land owner and his community.
• Be actively involved and visible to the public and the landowner. As the biosolids generator, you
will find it to your benefit to be visible, accountable, and responsive to your "customers". It
eliminates confusion about who is responsible for the quality of the application and any perceived
liability. Other types of projects with Metro's biosolids have been permitted and managed by private
vendors/contractors. Whenever issues or problems arise, the public usually looks beyond the vendor
to the generator for explanations or satisfaction of their complaint.
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• Make projects a team effort with the landowner, contractor, scientists and community. There is no
substitute for the support of your local research institution and the local newspaper editor/writer. The
researchers will provide a check and balance for your operation plans, keep your projects on sound
technical footing, and help with the problems that will surface. We found that working with and
establishing an open relationship with the local editor from the very outset of the Snoqualmie project
ensured that we had more reasonable and informed coverage when problems did arise.
• Monitor and publish results, both water quality and crop response.
Let the world know what a good job you're doing — talk, talk to community groups and professional
organizations. Presentations to the local SAP (Society of American Foresters) chapter or other
industry group will go a long way toward informing the forestry community in your locale about the
opportunities with biosolids.
PLANNING FOR THE NEXT DECADE
New Products. New Equipment
1992 is a year of transition and testing for Metro's forestry program. In addition to the current
rewatered applications, this year we will be testing the feasibility of dewatered cake applications. In
April and May we pilot-tested a side-cast spreader unit that flings dewatered material 200 feet out
into the plantation. This type of application could extend operations into the summer and allow us to
access areas of the tree farm that are only operable during the dry season. Such an operation would
also reduce costs by eliminating the need for dilution water and reducing crew size from five to two.
Later this year Metro's first dried biosolids product will become available through a contract for
biosolids drying with PCL/SMI. Metro will be testing some of this material in its existing forestry
and irrigated agriculture projects.
More Efficient Planning and Permitting
During the first two years of operations on the Snoqualmie Tree Farm, we concentrated on choosing
suitable sites for the upcoming year, doing a good job with operations, and following up carefully and
accurately with monitoring results and reports. Now with a new ten-year contract, plus two new
forms of biosolids product becoming available to us this year, we face the challenge of a more long-
term planning approach.
Our goals are to:
• predict number of acres and locations that will be available each year over the next decade;
• reduce amount and redundancy of staff and consultant work.
To accomplish the first goal, Metro staff are currently working on a screening process for the entire
tree farm. We are making field visits to all areas that have the potential to use liquid, cake, or dried
biosolids. Using the information gathered with the checklist in Figure 2, we will be developing a
database of stands that can be sorted by a number of variables: location, tree age, soil type, season
of application, and type of fertilizer product.
Permitting and environmental reviews to date have been somewhat piecemeal. Each project area of
160-200 acres has been evaluated and permitted separately, with separate operations plans and
individual reports of soils and ground water. To bring some continuity to the program and to
streamline our permitting efforts, this year we are developing two documents (in three-ring binders)
that can be used for all projects: (1) an operations plan for the entire tree farm, with site maps and
specific permit conditions located in appendices; and (2) a hydrogeology study for the tree farm,
again with site-specific studies added as needed.
265
-------
Research Needs
For the next couple of years, Metro and the University of Washington will be focusing on: further
fine-tuning of application rates, including the effects of residual nitrogen and multiple applications;
expansion of operations to other forest types such as hybrid cottonwood plantations and mixed
conifers in eastern Washington; and research on the fate of nutrients other than nitrogen.
One of the most exciting developments of the 1990s is the startup of similar forestry programs in
other parts of the US and the world. We're watching with great interest what's happening in
Vancouver, British Columbia; Christchurch, New Zealand; eastern Massachusetts, eastern Australia
and elsewhere.
For the biosolids generator, forest application can provide a type of reuse that has a reasonable cost,
is non food-chain, remote from homes, and provides economic benefits for the user. For the land-
owner, the use of biosolids can result in faster-growing trees, greater timber volumes, and long-term
improvements in productivity. With the information and operational experience gained by Metro and
other forest fertilization programs, more POTWs may find that forest fertilization is the right option
for their biosolids.
Acknowledgements
Although there have been many people who have helped shape the Silvigrow program, the authors
want to recognize three who "made it happen": Steve Anderson, area forester for the Weyerhaeuser
Snoqualmie Tree Farm; Charles Nichols, who designed the Silvigrow application/transfer equipment
and is now with the Sanitary District of Orange County, California; and Suzanne Schweitzer, who
developed the framework for designing and managing these projects and is now with East Bay
Municipal Utility District.
Any correspondence or questions can be addressed to: Peggy Leonard, Municipality of Metropolitan
Seattle, 821 Second Avenue, Mail Stop 81, Seattle, WA 98104-1598.
266
-------
m HAUL
APPLICATION
45 -T-
35 —
30 --
rj 20 -p
o
15
10 -r
5 —
COMPOST
FORESTRY
AGRICULTURE
(Yakima)
AGRICULTURE
(Adams)
AGRICULTURE
(Douglas)
Figure 1. Approximate haul and application costs for compost, forest, and agriculture projects (by wet tons averaging 23% solids).
267
-------
FIELD CHECKLIST
DATE OF FIELD CHECK:
FIELD EXAMINER:
LOCATION: (Section, Township, Range)
Attach map with boundaries marked.
SOILS
Information Source:.
Soil Series:
PROPERTY OWNER:.
ELEVATION:
NUMBER OF ACRES:.
NEARBY SITES:
Parent Material:.
Approx. Depth:_
.Does soil appear suitable?.
TOPOGRAPHY
Slope:
Presence of draws (mark on map):
Areas where slope may be critical factor (mark on map):.
SURFACE WATERS
Water body type and location (mark on map):.
Areas of poor drainage (standing water, wet-site indicators);
Buffers required (mark on map):.
VEGETATION
Tree species:.
Stocking levels:_
Understory:
.Average stand height:.
Species
Average Height
Average Cover (nearest 10%)
ACCESS
Main Roads: Grade:.
Width:
Overall Condition:
Any Limitations for Application Trails:.
COMMENTS/RECOMMENDATIONS:
ESTIMATE OF USABLE ACRES:
RECOMMENDED SEASON OF APPLICATION:,
Figure 2. Field checklist for evaluation of potential Silvigrow sites.
268
-------
Site Design
and Permitting
for Silvigrow Sites
Select Sites
Collect and Analyze
Soil Samples
Hydrogeology
Assessment
Design and
Mark
Trail System
Prescribe
Application Rates
(Univ. of WA)
Begin Background
Water Quality Monitoring
Operations
Plan
Environmental
Review
Prepare and Submit
Permit Application
Review of Application by
County Health Department and
State Dept. of Ecology
Site Visit
Construct Trails
Survey Trails for
Compartment Acreage
Prepare As-Built Maps;
Calculate Compartment Loadings
Hang Boundary and
Compartment Signs
Municipality of Metropolitan Seattle
4/92
Begin Operations
Figure 3. Steps in the design and permitting of forest application sites.
269
-------
Unit 24-08-02
Weyerhaeuser Snoqualmie Tree Farm
LEGEND
Erftflng Roacfe 133O
and Road Numtwn
Slop* Bufl*r
(A/rows point downstofw)
400'
To mix station
Figure 4. Trail map of typical Silvigrow unit. Units are named for the township, range, and section in which they are located—Unit
24-08-02 is located in T24N R8E, Section 2. This particular unit comprises 98 acres.
270
-------
Application Log
I = IME
A = Ag Chem
-~~ = End Lift
/*"
/
I
F
Load
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Date
Y/^Y
Jlu
4ju
f^AJf)_
17
18
19
20
21
22
23
24
25
26
27
28
29 1
30
31
32
Time
/.or
//••
-------
DAILY BOUNDARY AND BUFFER CHECK
Inspector
Date
UNITS WORKED TODAY
Unit/
Compartment
# Passes Tire Depressions Standing
per Day 0-6" 6-12" 12-18" Stuck Water
Trails (General conditions, incl. any Silvigrow on trails)
Buffers (Note any oversprays, spills, etc.)
Compartments (Application uniformity)
Figure 6. Field sheet for daily boundary and buffer checks by the site supervisor.
272
-------
LONG-TERM EFFECTS OF A SINGLE APPLICATION OF MUNICIPAL SLUDGE
ON ABANDONED MINE LAND1
BY
William E. Sopper and Eileen M. Seaker2
Abstract. In 1977, digested and dewatered municipal sludge
was applied and incorporated in spoil material at a rate of 184
Mg/ha on a 0.4 ha experimental plot on an abandoned strip mine
site in Pennsylvania. Data were collected for a five-year
period (1977-1981) to determine the effects of the sludge
application on the quality and growth of the herbaceous
vegetation, the chemical properties of the soil, and the
chemical quality of groundwater. In 1989, 12 years after
sludge application, the site was again resampled to determine
the long-term residual effects of the sludge application.
Results of the re-evaluation indicated that the single high
application of sludge facilitated the rapid development of a
vegetative cover which has persisted over the 12 years with no
apparent adverse effects on vegetation, soil, or groundwater.
Additional key words: Reclamation, trace metals, sludge
utilization, revegetation, groundwater quality.
Introduction
It is estimated that more than 7.7 million dry
metric tons of municipal sludge are currently
produced each year by the 15,300 public-owned
treatment works in the United States.
Approximately 25% of this is being land-applied for
its fertilizer and organic matter value (Federal
Register 1989). One of the most efficient uses for
sludge is the reclamation of disturbed lands, such
as those abandoned after coal mining which are
acidic, droughty, and devoid of organic matter.
Sludge has been shown to improve spoil structure,
water holding capacity, and bulk density in
addition to adding N, P, K, and other plant
nutrients (Sopper et al. 1982; Sopper and Seaker
1983).
Approximately 121,000 hectares of land in
Pennsylvania, strip mined prior to the federal
Surface Mining Control and Reclamation Act of 1977,
were abandoned after the coal was removed, leaving
vast areas of barren spoil (USDA 1980). These
sites have remained barren for years due to the
difficulty of establishing and maintaining
vegetation on the highly acidic material.
In 1977, a project was initiated in
Pennsylvania that introduced the concept of using
municipal sludge for revegetation of mined land to
the general public in order to gain public
acceptance and support. The specific objective of
the project was to demonstrate that municipal
sludge could be used, to reclaim strip mined land
and return it to potential agricultural use or to a
wildlife habitat in an environmentally acceptable
manner, without adverse effects on the quality of
the vegetation, soil, or water. Vegetation, soil,
and groundwater samples were collected over a five-
year period (1977-1981) and results of these
studies have been reported by Seaker and Sopper
(1984) .
Paper presented at the 1990 Mining and Reclamation Conference and
Exhibition, Charleston, West Virginia, April 23-26, 1990. The
research described in this article has been partially funded by the
U.S. Environmental Protection Agency through Grant No. S-804511-020
and CR807408010.
2
William E. Sopper is Professor of Forest Hydrology, School of Forest
Resources, The Pennsylvania State University, University Park, PA
16802 and Eileen M. Seaker is Environmental Consultant, 1917 E.
Branch Road, State College, PA 16801.
273
-------
The issue of the long-term effect of applying
single, large amounts of sludge in order to
revegetate mine land often arises. What happens
after all the sludge has been mineralized and all
the nutrients and trace metals have been released
to the soil and are potentially available for plant
uptake and leaching? Will the vegetative cover
persist or deteriorate?
One of the sites used in the 1977 project was
an abandoned strip nine bank located in Venango
County that had been backfilled and recontoured
after mining without top soil replacement. Several
revegetation attempts were unsuccessful. Dewatered
digested sludge was applied in May 1977 to a 0.2-ha
plot. In August, 1989, 12 years after sludge
application, the site was revisited and samples of
vegetation, soils, and groundwater were collected
to evaluate the long-term effects. The project was
originally designed as a demonstration to the
public, rather than an experiment. Subsampling was
employed, but statistical analyses could not be
performed on the data. Instead, general trends are
discussed.
Materials and Methods
Sludge Application
The surface soil was compacted, stony, and
extremely acid (pH 3.8). The 0.2 ha plot was
scarified with a chisel plow to loosen the surface
spoil material and agricultural lime was applied at
12.3 Mg/ha to raise the spoil pH to 7.0. Sludge
for the project was obtained from three local
wastewater treatment plants. The sludge was
applied at 184 Mg/ha with a manure spreader. The
average concentrations of nutrients and trace
metals and amounts applied in the sludge are given
in Table 1. The amounts of nutrients applied were
equivalent to applying an 11 (N) -9 (F205) -0 (K20)
chemical fertilizer at 22,400 kg/ha.
Table 1. Chemical analysis of dewatered sludge
applied and amounts of elements applied
at 184 Mg/ha rate (Dwt Basis)
Constituent
Total P
Total N
K
Ca
Mg
Zn
Cu
Pb
Ni
Cd
Average
Concentration
mg/kg
4624
12188
93
9970
2082
811
661
349
69
3.2
Amount
Applied
kg/ha
918
2388
18
1834
383
147
129
55
12
0.6
7.9
The amounts of trace metals applied are given
in Table 2 along with the U.S. Environmental
Protection Agency (EPA) and Pennsylvania Department
of Environmental Resources (PDER) interim guideline
recommendations (United States Environmental
Protection Agency 1977; Pennsylvania Department of
Environmental Resources 1977). It is quite obvious
that the amounts of trace metals applied were well
below the recommended lifetime limits except for
copper, which slightly exceeded the Pennsylvania
guidelines.
Immediately after sludge application and
incorporation, the site was broadcast seeded with a
mixture of two grasses (Kentucky-31 tall fescue, .
Festuea arundinacea Schreb., 22 kg/ha, Pennlate
orchardgrass, Dactvlis glomerata L., 22 kg/ha) and
two legumes (Penngift crownvetch, Coronilla varia
L. , 11 kg/ha, and Empire birdsfoot trefoil, Lotus
corniculatus L., 11 kg/ha). Then the site was
mulched with straw and hay at the rate of 3.8
Mg/ha.
Sampling and Analyses
A complete monitoring system was installed on
the plot to evaluate the effects of the sludge
applications on water quality, vegetation, and
soil. Two groundwater wells were drilled (up-
gradient and down-gradient) to sample the effects
of the sludge application on groundwater quality.
After sludge application, groundwater samples were
collected bi-weekly for the first two months and
monthly thereafter. Samples were analyzed for pH,
nitrate-N by ion-selective electrode (Ellis 1976),
dissolved Cu, Zn, Cr, Pb, Co, Cd, and Ni by atomic
absorption spectrophotometry (EPA Methods of
Chemical Analysis 1974).
Minesoil samples were collected at the 0 to IS,
and 15 to 30 cm depth, passed through a 2 mm sieve,
and analyzed for pH, Kjeldahl-N, Bray-P,
exchangeable K, Ca, and Mg by ammonium acetate
extraction, and dilute hydrochloric acid
extractable Cu, Zn, Cr, Pb, Cd, and Ni (Jackson,
1958). Exchangeable cation and extractable metal
concentrations were determined by atomic
absorption.
At the end of each growing season vegetation
growth responses were determined by measurements of
percentage areal cover, and dry matter production.
No crops were harvested over the 12-year period.
Individual samples of tall fescue, orchardgrass,
crownvetch, and birdsfoot trefoil from each plot
were collected for foliar analyses. Plant samples
were analyzed for Kjeldahl-N; P, K, Ca, Mg, by
plasma emission spectrometry (Baker et al. 1964),
and Cu, Zn, Cr, Pb, Co, Cd, and Ni by atomic
absorption (Jackson 1958) , after dry ashing and
digestion.
Results and Discussion
Vegetation
The site was completely vegetated by August
1977, three months after sludge application, which
has persisted .throughout the 12-year period.
Average annual dry matter production for the first
five years and in 1989 was as follows:
Year
1977
1978
1979
1980
1981
1989
AHY
Yield
Mg/ha
6.0
9.3
11.3
31.2
22.6
15.5
4.0
274
-------
Table 2. Trace metal loadings of Che sludge application
and lifetime loadings recommended by the EPA
and PDER.
Constituent
1
2
Cu
Zn
Cr
Pb
Ni
Cd
Hg
Average CEC
Sludge
Application
184 Mg/ha
129
147
74
55
12
0.6
0.09
of site ranged
No recommendation given by
EPA1
(CEC 5-15)
280
560
NR2
800
280
NR2
from 11.6 to 15.
EPA
PDER
112
224
112
112
22
3
0.6
.2 meq/lOOg
Dry matter production increased during the
first four years, leveling off in 1981. In 1989 it
was slightly lower but still well above the average
hay yield (AHY) for undisturbed farmland soils in
the county. During the first two years the two
grass species dominated the site, but by the third
growing season, the two legume species predominated
and persisted through the fifth year (1981) .
However, by 1989 the birdsfoot trefoil had almost
disappeared and now the dominating vegetative cover
consists mostly of crownvetch and orchardgrass.
For brevity, only the foliar analyses for
crownvetch and orchardgrass will be discussed.
Foliar concentrations of macronutrients are given
in Table 3. Nutrients (N and P) were all generally
higher in the sludge-grown plants. Potassium and
Ca were higher in the sludge-grown orchardgrass
than in control plants. Potassium and Ca were only
slightly lower in the sludge-grown birdsfoot
trefoil plants than in the control plants. Foliar
Mg concentrations were similar in both sludge-grown
and control plants. Nutrient levels in the sludge-
grown plants in 1989 were about the same level as
the first year when sludge was applied. There
appears to be little depletion of nutrients from
the site over the 12-year period. Birdsfoot
trefoil data are given in Table 3 because no
crownvetch plants were present on the control plot
for comparison. Macronutrient concentrations in
crownvetch on the sludge-amended plot are given in
Table 4. Concentrations were quite similar to
those of birdsfoot trefoil.
Foliar concentrations of Zn, Cu, Pb, Ni, and Cd
in orchardgrass and crownvetch are shown in Figures
1 to 5. Concentrations of Zn (Fig. 1), and Ni
(Fig. 4) tended to be higher in crownvetch than in
orchardgrass; whereas, concentrations of Cu (Fig.
2) tended to be higher in orchardgrass.
Concentration of Pb (Fig. 3) and Cd (Fig. 5) were
variable and showed no distinct trends. In
general, trace metal foliar concentrations tended
to be highest the first year and then decrease over
time. Except for Ni, foliar concentrations of
trace metals in the sludge-grown orchardgrass
plants were higher than in control plants. The
1989 values for Cu (Fig. 2) and Cd (Fig. 5) were
quite similar to those of 1981. Foliar
concentrations of Zn, Ni, and Pb showed a slight
increase from 1981 to 1989. Although sludge
application appeared to increase some trace metal
concentrations in the foliage, these increases were
minimal and well below the suggested tolerance
levels for agronomic crops (Melsted 1973). No
phytotoxicity symptoms were observed during the
study. The suggested tolerance levels are not
phytotoxic levels but suggest foliar concentration
levels at which decreases in growth may be
expected.
Spoil Chemical Status
Changes in spoil pH over time are shown in
Table 5. Spoil pH tended to increase from 1977 to
1979 and declined thereafter. This may explain why
some of the foliar trace metal concentrations
showed an increase in 1989. The nutrient status of
the spoil seemed to show a general increase in
concentrations of Kjeldahl-N up to 1981 and up to
1984 for Bray-phosphorus, K and Ca (Table 6). The
application of lime and sludge initially resulted
in a decrease in the concentration of Mg; however,
since 1978 there has been a steady increase. The
1989 values are lower but still quite adequate to
support plant growth.
Concentrations of extractable trace metals in
the 0 to 15 cm spoil depth are given in Table 7 and
for the 15 to 30 cm spoil depth in Table 8.
Concentrations of Cu, Zn, Cr, Pb, Cd, and Ni all
show a steady increase for the first five years
(1977-81). By this time, most of the sludge
organic matter was probably mineralized and most oi
the trace metals released to the surface spoil.
Results of spoil analyses in 1984 and 1989 showed a
gradual decrease in concentrations of all trace
metals. Although the sludge application seemed to
increase the concentrations of extractable trace
metals in the 0 to 15 cm spoil depth, these higher
concentrations are still within the normal ranges
for these elements in U. S. soils (Allaway 1968).
It appears that there is some leaching of trace
metals through the spoil profile. Concentrations
of trace metals in the 15 to 30 cm spoil depth show
a general increasing trend from 1977 to 1989.
Groundwater Quality
Results of the analyses of groundwater well
samples are given in Table 9. The values for Well
275
-------
Table 3. Mean foliar concentrations of macronutrient elements in
orchardgrass and birdsfoot trefoil collected from the
control and sludge-amended plots.
Sludge
application
Year
Orchardgrass
Birdsfoot trefoil
Ca
Mg
K
Ca
Mg
Mg/ha
0 1977
1978
1979
1980
1981
1989
184 1977
1978
1979
1980
1981
1989
0
1
1.
1
1.
2.
1.
1.
1.
2.
2.
-L
.92
.17
.11
.22
.67
.62
26
33
70
57
36
0.18
0.22
0.24
0.18
0.17
0.40
0.37
0.51
0.42
0.37
0.37
1.51
2.41
1.86
1.62
1.82
2.84
2.01
2.53
2.65
2.38
2.24
0.36
0.30
0.32
0.68
0.42
0.84
0.49
0.47
0.45
0.53
0.45
0.23
0.22
0.20
0.22
0.30
0.31
0.28
0.23
0.23
0.26
0.22
1.03
2.59
2.11
3.32
2.31
3.64
1.27
3.57
2.93
4.03
2.38
0.24
0.14
0.17
0.17
0.17
0.27
0.36
0.25
0.25
0.26
0.16
1.93
1.74
1.92
1.89
1.71
1.46
2.30
1.56
1.62
1.69
1.01
0
1
1
1
0
1
0,
0.
1
1.
0.
.61
.82
.02
.52
.92
.99
.59
.54
.27
.14
.65
0.26
0.40
0.23
0.29
0.22
0.28
0.25
0.20
0.18
0.23
0.23
No plants available for sampling
Table 4. Mean foliar concentrations of macronutrient elements in
crownvetch on the sludge-amended plot.
Year
Crownvetch
K
Ca
Mg
1977
1978
1979
1980
1981
1989
3.36
2.35
3.35
3.00
3.78
2.62
0.34
0.37
0.22
0.27
0.31
0.21
1.64
3.14
1.29
1.89
1.89
2.20
2.63
0.96
1.68
1.72
1.25
0.91
0.42
0.45
0.25
0.29
0.23
0.26
Table 5. Changes in Spoil pH over the thirteen year period
Depth
Soil pH
cm
0-15
15-30
May
19771
3.8
3.8
Sept
1977
6.2
4.2
Nov
1978
6.7
4.6
Oct
1979
7.3
5.1
May
1981
5.8
3.4
Aug
1989
5.4
5.6
Pre-treatment samples
1 (control) reflect quality of groundwater for the
disturbed mine site. Well 2 reflects the effects
of the sludge application on water quality. Depth
to the water table was 4.9 m in Well 1 and 3.0 in
Well 2 in 1989. During the first five years (1977
to 1981) the water table fluctuated between 4.4 to
5.3 m in Well 1 and between 2.5 and 3.4 ra in Well
2. Results indicate that the sludge application
did not appear to have any significant effect on
groundwater concentrations of nitrate-N. Average
monthly concentrations of NC>3-N were below 10 mg/1
(maximum concentration for potable water) for all
months sampled during the five-year period (1977-
81). The highest monthly values were 3.0 mg/1 for
the control well and 2.4 mg/1 for Well 2.
Application of lime and sludge and subsequent
revegetation appears to have had a positive effect
on groundwater pH (Table 9) . Groundwater pH
increased from 4.6 (1977) to 6.0 by 1981. Results
of the 1989 sampling indicated a pH of 6.6. There
has also been a gradual increase in pH in the
276
-------
Table 6. Changes in concentrations of Kjeldahl-nicrogen, Bray-
phosphorus and exchangeable cations in the spoil collected
at the 0-15 cm depth
Year
Kjeldahl
Nitrogen
Bray
Phosphorus
K
Ca
Mg
.
May
Sept
1 Pre
19771
1977
1978
1979
1981
1984
1989
-sludge
0.04
0.05
0.09
0.16
0.34
—
0.12
samples
2
11
9
38
79
91
83
12
19
23
46
45
74
30
541
1222
2600
3873
1298
1440
733
452
32
40
53
99
108
84
Table 7. Changes in concentrations of extractable trace metals from
spoil collected at the 0-15 cm depth following sludge
application.
Sampling
Date
May
Sept
Normal
for U.
19771
1977
1978
1979
1981
1984
1989
Range
S. Soils
Cu
2.5
10.8
8.8
58.7
87.3
57.6
51.9
2-
100
Zn
2
7
7
56
74.
59.
37.
10-
300
.9
.7
. 7
.9
.6
6
8
Cr2
0.2
0.4
0.2
1.7
3.5
...
---
5-
3000
Pb
•gAg -•
0.
3.
2.
13.
22.
14.
13.
2-
200
Cd
5
5
3
0
7
8
5
0
0
0.
0.
0.
0.
0.
0.
7.
.02
.04
.02
.27
95
56
42
01
00
Ni
1
0
1.
1.
2.
2.
2.
5-
.1
.9
.2
.5
8
8
0
500
May 1977 values represen
Values for Cr are total concentrations.
conditions
control well from pH 4.4 to pH 5.8. Since 1980,
attempts have been made to reclaim the control area
by conventional methods using lime and fertilizer.
The amounts of lime and fertilizer applied and
frequency of application are not known as the coal
company is no longer in business. However, these
applications and vegetation growth probably
contributed to the increase in groundwater pH in
the control well.
There appears to be no significant increase in
any of the trace metal concentrations over the
initial five-year period (1977-1981) in the
groundwater samples from Well 2 compared to the
control well (Table 9). From 1977 to 1981 most of
the monthly concentrations were within the U.S.
Environmental Protection Agency drinking water
standards. The only exception was Pb which
exceeded the limit of 0.05 mg/1 for both the
control well and Well 2, probably resulting from
solubilization upon weathering after mining. The
highest monthly Pb values were 0.28 mg/1 in the
control well and 0.33 mg/1 in Well 2 in 1978, and
the mean annual Pb concentrations were 0.19 and
0.20 rag/1 for control well and Well 2,
respectively. By 1981, however, the mean annual Pb
concentrations had decreased to 0.04 and 0.05 mg/1
for the two wells. Results of analyses of the
groundwater samples collected in 1989 had extremely
low concentrations of all trace metals in both
wells in comparison to values for the initial five
years (1977-81).
Conclusions
Re-evaluation of an abandoned strip mine spoil
bank 12 years after being amended with 184 Mg/ha of
277
-------
Table 8. Changes in concentrations of extractable trace metals from
spoil collected at the 15-30 cm depth following sludge
application.
Sampling
Date
May
Sept
19771
1977
1978
1979
1981
1989
Cu
3
4
2
9
2
13.
.0
.0
.5
.2
.4
,8
Zn
2.4
2.0
1.7
8.7
2.8
10.2
Cr
0
0
<0
0.
0.
0.
.10
.10
.01
,28
05
43
Pb
mg/1
0
1
1,
2.
0.
3.
iCg - -
.6
.3
.3
.4
5
8
Cd
0
0
0.
0.
0.
0.
.020
.010
,007
,026
014
122
Ni
1.0
0.4
0.7
0.2
0.4
1.9
May 1977 values represent pretreatment conditions
Values for Cr are total concentrations
Table 9. Mean annual concentrations of nitrate - N and trace metals in
groundwater
Site
Year1 pH N03-N Cu
Zn
Cr
Pb
Cd
Ni
Well 1
1977
(control) 1978
Well 2
(sludge)
1979
1980
1981
19892
1977
1978
1979
1980
1981
19892
4.4
4.3
4.6
5.5
5.7
5.8
4.6
4.5
4.4
5.7
6.0
6.6
EPA drinking
1.4
<0.5
<0.5
0.6
0.7
0.02
1.1
<0.5
<0.5
0.6
0.6
0.06
10
0.22
0.23
0.17
0.05
0.06
0.01
0.10
0.14
0,18
0.05
0.05
0.01
1
4.13
2.02
1.48
0.89
0.83
0.09
3.39
3.29
1.49
1.05
0.57
0.07
5
0
0
0
0,
0
0.
0.
0.
0.
0.
<0.
0.
- Ul£/
.02
.01
.03
.05
.03
,001
03
01
03
04
02
001
05
0.14
0.19
0.13
0.09
0.04
0.01
0.09
0.20
0.13
0.11
0.05
0.01
0.05
0
0
0
0
0
0
0
o.
0
0,
0,
0
0.
.006
.002
.001
.001
.003
.001
.001
.002
.001
.001
.001
.001
010
3.67
0.98
0.50
0.50
0.31
0.06
2.67
1.26
0.97
0.76
0.31
0.04
- . .
water standard
Values
Average
are annual means of monthly
of three
samples collected
samples.
in August
1989.
municipal sludge indicates that a single large
application of sludge can be used successfully to
revegetate mine lands with no apparent adverse
effects on vegetation, spoil, or groundwater
quality.
Literature Cited
Allaway, W. H. 1968. Agronomic controls over the
environmental cycling of trace metals. Adv. In
Agron. 20:235-271.
Baker, D. E., G. W. Gorsline, C. B. Smith, W. I.
Thomas, W. E. Grube, and R. L. Ragland. 1964.
Technique of rapid analyses of corn leaves for
eleven elements. Agron. J. 56:133-136.
Ellis, B. G. 1976. Analyses and their
interpretation for wastewater application on
agricultural land. North Central Regional
Research Publication 235-Sec. 6.
Federal Register. 1989. Standards for the
Disposal of Sewage Sludge. Proposed Rule Vol.
54(23), Feb. 6, 1989, Part II, 40CFR parts 257
and 503, p. 5746-5902.
Jackson, M. L. 1958. Soil Chemical Analysis.
Prentice-Hall, Inc., Englewood Cliffs, NJ.
278
-------
Joost, R. E., J. H. Jones, and F. J. Olsen. 1981.
Physical and chemical properties of coal refuse
as affected by deep incorporation of sewage
sludge and/or limestone, p. 307-312. In:
Proc. Symp. on Surface Mining Hydrol.,
Sedimentol., and Reclamation. (Univ. of
Kentucky, Lexington, KY, 7-11 Dec. 1981).
Melsted, S. W. 1973. Soil-plant relationships.
p. 121-128. Jn: Recycling Municipal Sludges
and Effluents on Land, Nat. Assoc. of State
Universities and Land Grant Colleges,
Washington, DC.
Pennsylvania Department of Environmental Resources.
1977. Interim guidelines for sewage sludge use
for land reclamation. In: The Rules and
Regulations of the Department of Environmental
Resources, Commonwealth of Pennsylvania, Chapt.
75, Subchapt. C, Sec. 75.32.
Seaker, E. M. and W. E Sopper. 1984. Relcamation
of bituminous strip mine spoil banks with
municipal sewage sludge. Reclam. Reveg. Res.,
3:87-100.
Sopper, W. E., E. M. Seaker, and R. K. Bastian
(Editors). 1982. Land Reclamation and Biomass
Production with Municipal Wastewater and
Sludge. The Pennsylvania State Unviersity
Press, University Park, PA 16802.
Sopper, H. E. and E. M. Seaker. 1983. A guids for
revegetation of mined land in eastern United
States using municipal sludge. Institute for
Research on Land and Water Resources, The
Pennsylvania State University, Universit Park,
PA., 93 pp.
United States Department of Agriculture 1980.
Soil and Water Resource Conservation Act:
Appraisal 80. USDA, Washington, D. C.
United States Environmental Protection Agency
1974. Methods for Chemical Analysis of Water
and Wastes. Washington, D. C.
United States Environmental Protection Agency.
1977. Municipal Sludge Management:
Environmental Factors. Tech. Bull. EPA 430/9-
76-004, MCD-28.
300
<
120
110
100
90
80
70
60
50
40
30
20
10
SUGGESTED TOLERANCE LEVEL
•——GOG- 184 Mg/ha
• OG- 0 Mg/ha
Q—O cv" 184 Mg/ha
O
1977 1978 1979 1980
1981
1989
Figure 1. Mean foliar concentration of Zn in orchardgrass
and crownvetch collected from the control and
sludge-amended plots.
279
-------
SUGGESTED TOLERANCE LEVEL
9 9 OG" 184 M§/ha
• OG- 0 Mg ha
O—O CV- 184 Mgrtia
1977
1978
1979
1980
1981
1989
Figure 2. Mean foliar concentration of Ca in
orchardgrass and crownvetch collected
from the control and sludge-amended
plots.
10
SUGGESTED TOLERANCE LEVEL
8
7
I 6
Q)
£ 5
e
S 4
O
u.
3 -
2 -
•OG- 184 Mfl/ha
OG- 0 Mg'tia
O CV- 184 Mg/ha
1977
1978
1979
1i80
1981
Figure 3. Mean foliar concentration of Pb in
orchardgrass and crownvetch collected
from the control and sludge-amended
plots.
280
-------
SUGGESTED TOLERANCE LEVEL
• 0OG- 194 Mg/ha
• OG- 0 Mg/ha
O--O cv" 184 Mg/ha
1977
1978
1979
Figure 4. Mean foliar concentration of Ni in
orchardgrass and crownvetch collected
from the control and sludge-amended
plots.
SUGGESTED TOLERANCE LEVEL
• > OG- 184 Mg/ha
• OG- 0 Mg/ha
O Q CV- 184 Mg/ha
1977
1978
1979
Figure 5. Mean foliar concentration of Cd in orchardgrass
and crownvetch collected from the control and
sludge-amended plots.
281
-------
Citation for this Publication:
Sopper, W.E. and Eileen M. Seaker. 1990. Long-Term Effects of
a Single Application of Municipal Sludge on Abandoned Mine
Land. Proc. of The 1990 Mining and Reclamation Conference
and Exhibit, J. Skousen et al. (eds.), Vol. II: 579-587,
West Virginia University, Morgantown, WV.
282
-------
Appendix B
Federal Sewage Sludge Contacts
Table B-1. EPA Regional Sewage Sludge Contacts
REGION 1
Thelma Hamilton (WMT-ZIN)
JFK Federal Bldg.
One Congress St.
Boston, MA 02203
(617) 565-3569
Fax (617) 565-4940
REGION 2
Alia Roufaeal
Water Management Division
26 Federal Plaza
New York, NY 10278
(212) 264-8663
Fax (212) 264-9597
REGION 3
Ann Carkhuff (3WM55)
841 Chesnut St.
Philadelphia, PA 19107
(215) 597-9406
Fax (215) 597-3359
REGION 4
Vince Miller
Water Division
345 Courtland St., NE.
Atlanta, GA 30365
(404)347-3012 (ext. 2953)
Fax (404) 347-1739
REGION 5
Ash Sajjad (5WQP-16J)
Water Division
77 W Jackson Blvd.
Chicago, IL 60604-3590
(312)886-6112
Fax (312) 886-7804
REGION 6
Stephanie Kordzi (6-WPM)
Water Management Division
1445 Ross Ave., #1200
Dallas, TX 75202-2733
(214)665-7520
Fax (214) 655-6490
REGION 7
John Dunn
Water Management Division
726 Minnesota Ave.
Kansas City, KS 66101
(913) 551-7594
Fax (913) 551-7765
REGION 8
Bob Brobst (8WM-C)
Water Management Division
999 18th St., Suite 500
Denver, CO 80202-2405
(303) 293-1627
Fax (303) 294-1386
REGION 9
Lauren Fondahl
Permits Section
75 Hawthorne St. (W-5-2)
San Francisco, CA 94105
(415) 744-1909
Fax (415) 744-1235
REGION 10
Dick Hetherington (WD-184)
Water Management Division
1200 Sixth Ave.
Seattle, WA98101
(206) 553-1941
Fax (206) 553-1775
283
-------
U.S. EPA Regions
Region—State
4—Alabama
10—Alaska
9—Arizona
6—Arkansas
9—California
8—Colorado
1—Connecticut
3—Delaware
3—Washington, DC
4—Florida
4—Georgia
9—Hawaii
10—Idaho
5—Illinois
5—Indiana
7—Iowa
7—Kansas
4—Kentucky
6—Louisiana
Region—State
1—Maine
3—Maryland
1—Massachusetts
5—Michigan
5—Minnesota
4—Mississippi
7—Missouri
8—Montana
7—Nebraska
9—Nevada
1—New Hampshire
2—New Jersey
6—New Mexico
2—New York
4—North Carolina
8—North Dakota
5—Ohio
6—Oklahoma
10—Oregon
Region—State
3—Pennsylvania
1—Rhode Island
4—South Carolina
8—South Dakota
4—Tennessee
6—Texas
8—Utah
1—Vermont
3—Virginia
10—Washington
3—West Virginia
5—Wisconsin
8—Wyoming
9—:American Samoa
9—Guam
2—Puerto Rico
2—Virgin Islands
Figure B-1. Map of U.S. EPA regions.
284
-------
Appendix C
Permit Application Requirements
Permits that are issued to publicly owned treatment
works (POTWs) must include standards for sewage
sludge use or disposal. In addition, EPA may issue
sewage sludge permits to other "treatment works
treating domestic sewage" (TWTDS) (i.e., treatment
works that generate, change the quality of, or dispose
of sewage sludge).
The EPA's sewage sludge permit program regulations
establish a framework for permitting sewage sludge use
or disposal. The regulations require submission of a
permit application that provides the permitting authority
with sufficient information to issue an appropriate permit.
A permit application must include information on the
treatment work's identity, location, and regulatory status,
as well as information on the quality, quantity, and ulti-
mate use or disposal of the sewage sludge managed at
the treatment works.
Because the sewage sludge permitting regulations were
promulgated several years before the Part 503 stand-
ards, they describe the required application information
in broad, almost generic terms. Currently, EPA is devel-
oping application forms and the Agency is planning to
revise the permit application regulations to reflect spe-
cifically the Part 503 standards and to enable permit
writers to tailor permit requirements to facilities' specific
use or disposal practices.
The deadlines for submitting permit applications were
revised in 1993 and are as follows:
• Applicants requiring site-specific pollutant limits in
their permits (e.g., sewage sludge incinerators) and
facilities requesting site-specific limits (e.g., some
surface disposal sites) were required to submit appli-
cations by August 18, 1993.
• All other applicants with National Pollutant Discharge
Elimination System (NPDES) permits are required to
submit sewage sludge permit applications at the time
of their next NPDES permit renewals.
• So-called sewage sludge-only (non-NPDES) treat-
ment works that are not applying for site-specific lim-
its, and are not otherwise required to submit a full
permit application, only need to submit limited
screening information and must have done so by
February 19, 1994.
The permit application information that must be submit-
ted depends upon the type of treatment works and which
sewage sludge management practices the treatment
works employs. Questions on permit applications should
be directed to the appropriate State and EPA Regional
Sewage Sludge Coordinators listed in Appendix B.
Sludge-Only Treatment Works
The limited screening information submitted by a sew-
age sludge-only treatment works typically will include
the following:
• Name of treatment works, contact person, mailing
address, phone number, and location.
• Name and address of owner and/or operator.
• An indication of whether the treatment works is
a POTW, privately owned treatment works, fed-
erally owned treatment works, blending or treat-
ment operation, surface disposal site, or sewage
sludge incinerator.
• The amount of sewage sludge generated (and/or re-
ceived from another treatment works), treated, and
used or disposed.
• Available data on pollutant concentrations in the sew-
age sludge.
• Treatment to reduce pathogens and vector attraction
properties of the sewage sludge.
• Identification of other facilities receiving the sewage
sludge for further processing or for use or disposal.
• Information on sites where the sewage sludge is used
or disposed.
285
-------
Facilities Submitting Full Permit Applications
A full permit application is much more comprehensive
than the limited screening information described above
for sewage sludge-only facilities. A full permit application
typically will include the following information:
General Information
• Name of treatment works, contact person, mailing
address, phone number, and location.
• Name and address of owner and/or operator.
• An indication of whether the treatment works is a POTW,
privately owned treatment works, federally owned treat-
ment works, blending or treatment operation, surface
disposal site, or sewage sludge incinerator.
• Whether the treatment works is a Class I sludge man-
agement facility (i.e., a pretreatment POTW or another
facility designated Class I by the permitting authority).
• The NPDES permit number (if any) and the number
and type of any relevant Federal, State, or local en-
vironmental permits or construction approvals applied
for or received.
• Whether any sewage sludge management occurs on
Native American lands.
• A topographic map showing sewage sludge manage-
ment facilities and water bodies 1 mile beyond the
property boundary and drinking water wells 1/4 mile
beyond the property boundary.
• Results of hazardous waste testing for the sewage
sludge, if any.
• Data on pollutant concentrations in the sewage sludge.
Information on Generation of Sewage Sludge or
Preparation of a Material From Sewage Sludge
• The amount of sewage sludge generated.
• If sewage sludge is received from off site, the amount
received, the name and address of the offsite facility,
and any treatment the sewage sludge has received.
• Description of any treatment at the applicant's facility
to reduce pathogens and vector attraction properties
of the sewage sludge.
• Description of any bagging and distribution activities
for the sewage sludge.
• If sewage sludge is provided to another facility for
further treatment, the amount provided, the name and
address of the receiving facility, and any treatment
occurring at the receiving facility.
Information on Land Application of Sewage
Sludge
• The amount of bulk sewage sludge applied to the land.
• The nitrogen content of bulk sewage sludge applied
to the land.
• The name and location of land application sites, and
a copy of the land application plan if all sites have
not been identified.
• The name and address of the owner and the person
who applies bulk sewage sludge to each site.
• The site type and the type of crop or other vegeta-
tion grown.
• Description of any processes at each land application
site to reduce vector attraction properties of the sewage
sludge.
• Ground-water monitoring data, if available.
• If bulk sewage sludge is subject to cumulative pollut-
ant loading rates, information on how the necessary
tracking and notification requirements will be met.
• If bulk sewage sludge is applied to the land in a
different state, information on how the permitting
authority in the receiving state will be notified.
All permit applications must be signed and certified. The
permitting authority may request additional information
to assess sewage sludge use or disposal practices,
determine whether to issue a permit, or identify appro-
priate permit requirements.
286
-------
Appendix D
Conversion Factors
Table D-1. Conversion Factors (Metric to U.S. Customary)
Metric
Name
Centimeter(s)
Cubic Meter
Cubic Meters Per Day
Cubic Meters Per Hectare
Degrees Celsius
Gram(s)
Hectare
Kilogram(s)
Kilograms Per Hectare
Kilograms Per Hectare Per Day
Kilograms Per Square Centimeter
Kilometer
Kilowatt
Liter
Liters Per Second
Metric Tonne
Metric Tonnes Per Hectare
Meter(s)
Meters Per Second
Micrograms Per Liter
Milligrams Per Liter
Square Centimeter
Square Kilometer
Abbreviation
cm
m3
m3/d
m3/ha
°C
g
ha
kg
kg/ha
kg/ha/d
kg/cm2
km
kW
L
L/s
t
t/ha
m
m/s
|ig/L
mg/L
cm2
km2
Multiplier
0.3937
8.1071 x 10'4
35.3147
264.25
2.641 7 x 10'4
1 .069 x 1 0'4
1 .8 (°C) + 32
0.0022
0.24711
0.004
2.205
0.0004
0.893
14.49
0.6214
1.34
0.0353
0.264
0.035
22.826
15.85
0.023
1.10
0.446
3.2808
2.237
1.0
1.0
0.155
0.386
U.S.
Abbreviation
in
acre-ft
ft3
Mgal
Mgal/d or MGD
Mgal/acre
°F
Ib
acre
mi2
Ib
T/ac
Ib/ac/d
Ib/in2
mi
hp
ft3
gal
ft3/s
gal/d
gal/min
Mgal/d
T
T/ac
ft
mi/h
ppb
ppm
in2
mi2
Customary Unit
Name
inches
a ere -foot
cubic foot
million gallons
million gallons per day
million gallons per acre
degrees Fahrenheit
pound(s)
acre
square miles
pound(s)
tons per acre
pounds per acre per day
pounds per square inch
mile
horsepower
cubic foot
gallons
cubic feet per second
gallons per day
gallons per minute
million gallons per day
ton (short)
tons per acre
foot (feet)
miles per hour
parts per billion
parts per million
square inch
square mile
287
-------
Table D-2. Dry Weight Basis
BIOSOLIDS FACT SHEET
EPA REGION* Vm—M>DES Branch-Permts Program
999 ISA Street. Suite 500, Denver. Colorado 80202
Mr, Robert Brobsi
EPA REGION X—NPDES Branch-Permits Program
1200 6ih Avenue, Seattie, Washington 9S101
Mr. Richard Hecaherington
3.3
DRY WEIGHT
BASIS (FS/793/03/1)
Laboratory results for sludge are typically reported in one of two forms,
wet weight (i.e., mg/L) or a dry weight (i.e., mg/kg). You should
request your laboratory to provide the results on a dry weight basis. In
the event that the laboratory results are reported on a wet weight basis
(i.e., in mg/L), the results for each pollutant in each sample must be
recalculated to determine the dry weight concentration. To accomplish
this conversion, the percent total solids in the sludge sample must be
known.
The following equation can be used to determine the dry weight
concentration because the equation uses the assumption that the specific
gravity of water and sewage sludge are both equal to one. However, this
assumption holds true only when the solids concentration in the sludge is
low. The calculated dry weight concentration may vary slightly from the
actual concentration as the solids content increases because the density of
the sewage sludge may no longer be equal to that of water. Typically,
this concern is unrealized as the solids content of sludge is usually low.
EPA is aware of this potential problem and may make a determination
regarding this matter at a later date.
Determine the pollutant concentration on a dry weight basis using the
following abbreviated conversion:1
PC(dry»mg/kg) = /POwet. mg/L)\
\ % total solids /
where PC = Pollutant Concentration
A unit conversion is incorporated into the equation.
lAnalytical Methods Used in the National Sewage Sludge Survey. August !988. U.S. EPA Office of Water Regulations and
Standards (WH-552), Industrial Technology Division, Washington, DC.
288
-------
Table D-2. (continued)
FS/793/03/1
Dry Weight Basis
Determine the pollutant concentration on a dry Weight basis using the following conversion:
PC(dry,mg/kg) = /PCfwet. mg/L)|
I % total solids I
Example #1: Determine the dry weight concentrations of the pollutants.
The laboratory analysis of your sludge yielded the following results:
As - 6.6 mg/L Cd - 5.5 mg/L Cr - 192.5 mg/L Cu - 374 mg/L
Pb - 44 mg/L Hg - 0.22 mg/L Mo - 0.88 mg/L Ni - 44 mg/L
Se-2.2 mg/L Zn - 330 mg/L
The percent solids was determined to be 22%.
Therefore, using the given equation, the dry weight concentration of As can be determined as follows:
6.6 mg/L (As.wet) = 6.6 mg/L = 30 mg/kg As, dry weight
22 % 0.22
Remember to convert the percent total solids to a decimal by multiplying by 100.
The remainder of the converted results are:
Cd=25mg/kg, Cr=875mg/kg, Cu=l,700mg/kg, Pb=200mg/kg, Hg=lmg/kg, Mo=4mg/kg,
Ni=200mg/kg, Se=10mg/kg, Zn=l,500mg/kg
( )mg/L = ( )mg/L = ( )mg/kg dry weight
( ) % 0.
289
-------
Table D-3. Conversion of Sludge Volume to Dry Metric Tons.
_ , ~,, - ,
SOR COIWIRIING $UJD6fe^OL|fll TO:DR^ METRIC TOMST
Applicability;
The amount of sewage sludge used or disposed must be reported as metric tons, dry weight.
Procedure:
Step 1: Convert the common measure (e.g., cubic yards or gallons) to the English System or short tons, dry
weight.
Dry short tons = gallons of sewage sludge x — x x Percent Solids
gallon 2000 Ib
8.34 Ib/gal is the density of water. This equation is therefore applicable to liquid sludges (less
than 5 percent solids). Site-specific densities may be determined and substituted in this equation
for a more accurate result.
Dry short tons = cubic yards (wet) of sewage sludge x x x Percent Solids
cubic yard 2000 Ib
Y Ib/cubic yard is the site-specific bulk density of the sewage sludge. It must be determined for
each type of sludge prepared and substituted in the equation for accurate results.
Step 2: If you are starting with the English System or short tons, convert them to dry weight.
Dry tons = Wet tons x Percent Solids
Step 3: Convert the English System or short tons to metric tons.
Dry metric tons = Dry short tons x .907
Source: U.S. EPA. 1993. Preparing sewage sludge for land application or surface disposal. EPA/831/B-93/002a.
Washington, DC.
290
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