EPA/625/R-95/002
                                                       September 1995
                   Process Design Manual

Surface Disposal of Sewage Sludge and Domestic Septage
                   U.S. Environmental Protection Agency
                   Office of Research and Development
                        Washington, DC 20460
                                                      Printed on Recycled Paper

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                                     Disclaimer
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
Chapter 1   Introduction
            1.1  Regulatory Overview		..... —	  1
            1.2  Compliance and Enforcement of the Part 503 Rule	  4
            1.3  Relationship of the Federal Requirements to State Requirements	  4
            1.4  How To Use This Manual	  4
            1.5  Use of the Terms "Sludge" and "Septage" in This Manual	  5
            1.6  References	  5
Chapter 2  Active Sewage Sludge Units
            2.1  Introduction	  9
            2.2  Overview of Sewage Sludge Disposal Sites	  10
            2.3  Monofills	  11
                 2.3.1  Trenches	  11
                       2.3.1.1     Narrow Trenches	  .12
                       2.3.1.2     Wide Trenches	  14
                 2.3.2 Area Fills	  14
                       2.3.2.1     Area Fill Mound	  15
                       ฃ.3.2.2     Area Fill Layer	  15
                       2.3.2.3     Diked Containment..:	,	  15
             2.4  Piles	  16
             2.5  Surface Impoundments and Lagoons	  16
             2.6  Dedicated Surface Disposal Sites	  17
             2.7  Dedicated Beneficial Use Sites	  18
             2.8  Codisp&sal at a Municipal Solid Waste Landfill	  18
                  2.8.1  Sludge/Solid Waste Mixture	  18
                  2.8.2 Sludge/Soil Mixture	  18
             2.9  References	• •  19
 Chapter 3  Characteristics of Sludge, Septage, and  Other Wastewater Solids
             3.1  Introduction	  21
             3.2  Typef of Wastewater Solids	  21
                  3.2.rSlu
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                                         Contents (continued)
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                       3.2.1.3    Chemical Sludge	 21
                  3.2.2 Domestic Septage	 21
                  3.2.3 Other Wastewater Solids	 23
                       3.2.3.1     Screenings	.. •	 23
                       3.2.3.2    Grit	 23
                       3.2.3.3    Scum	 23
             3.3  Characteristics of Sewage Sludge Affecting Disposal From a Regulatory Perspective ... 23
                  3.3.1 Part 503		 24
                       3.3.1.1     Heavy Metals	 24
                       3.3.1.2     Pathogens		 25
                                  Class A Requirements	 25
                                  Class B Requirements	 25
                                  Applying Soil Cover	 26
                       3.3.1.3     Vector Attraction	 26
                       3.3.1.4     Frequency of Monitoring	 26
                       3.3.1.5     Organic Chemicals	 26
                       3.3.1.6     Nitrogen	 27
                  3.3.2 Part 258	 28
                       3.3.2.1     Exclusion of Hazardous Waste From Municipal Solid Waste Landfills... 28
                       3.3.2.2     Liquids Restriction	 28
             3.4  Characteristics of Sewage Sludge Affecting Disposal From a Technical Perspective	 29
                  3.4.1 Solids Content	 29
                  3.4.2 Sludge Quantity	 30
                  3.4.3 Organic Content	,	 30
                  3.4.4 PH	.. .	 30
             3.5   References	 30

Chapter 4   Site Selection
             4.1   Purpose and Scope	  33
             4.2   Regulatory Requirements	33
                 4.2.1 Part 503	  33
                       4.2.1.1     Protection of Threatened or Endangered Species	  33
                       4.2.1.2    Restriction of Base Flood Flow	  34
                       4.2.1.3     Geological Stability	  35
                       4.2.1.4     Protection of Wetlands	  37
                                 Other Federal Regulations	  37
                       4.2.1.5     Protection of Surface Water—Collection of Runoff and Leachate	  39
                       4.2.1.6     Protection of Ground Water	  39
                                                  IV

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                                        Contents (continued)
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                                 Ground-Water Data Sources	  39
                                 On-site Drilling	  39
                 4.2.2 Part 258.	  40
            4.3  Additional Considerations	  41
                 4.3.1 Site Life and Size	  41
                 4.3.2 Topography			  44
                 4.3.3 Soils	  44
                      4.3.3.1     Physical/Hydraulic Properties			  45
                      4.3.3.2     Chemical Properties	•	  45
                 4.3.4 Vegetation	  46
                 4.3.5 Meteorology	  46
                 4.3.6 Site Access	  46
                 4.3.7 Land Use	  46
                 4.3.8 Archaeological or Historical Significance	  46
                 4.3.9 Costs	  46
            4.4  Site Selection: A Methodology for Selecting Surface Disposal Sites	  46
                 4.4.1 Step 1: Initial Site Assessment and Screening	  48
                 4.4.2 Step 2: Site Scoring and Ranking	  51
                 4.4.3 Step 3: Site Investigation	  53
                 4.4.4 Step 4: Final  Selection	  53
            4.5  References	:	•	  55
Chapter 5  Public Participation Programs
            5.1  Introduction	  57
            5.2  Objectives	  57
            5.3  Value of a PPP	  57
            5.4  PPP Participants	•	•	  57
                 5.4.1  Public Participants	  57
                 5.4.2 Program Staff	  58
            5.5  Design of a PPP	  59
                 5.5.1  Initial Planning Stage	  59
                 5.5.2 Site Selection Stage	  60
                 5.5.3 Selected Site and Design  Stage	  61
                 5.5.4 Construction  and Operation Stage	  61
            5.6  Timing of Public Participation Activities	 62

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                                        Contents (continued)
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            5.7  Potential Areas of Public Concern	;	  62
            5.8  Conclusion	'	  62
            5.9  References	  63
Chapter 6  Field Investigations
            6.1  Purpose and Scope	  65
            6.2  Regulatory Requirements	  65
                 6.2.1  Part 503 Regulation	  65
                 6.2.2 Part 258 Regulations	  65
                 6.2.3 Other Regulatory Requirements and Programs	  65
            6.3  Collection of General Site Information	  66
                 6.3.1  Topography and Aerial Photographs	  66
                 6.3.2 Soils,  Geologic,  Geophysical, and Geotechnical  Information	  70
                 6.3.3 Hydrologic, Wetland, and Climatic Information.	  74
            6.4  Site-Specific Data Collection	  74
                 6.4.1  Site Land and Topographic Survey	  76
                 6.4.2 Soil and Geologic Characterization	  76
                 6.4.3 Hydrogeologic Characterization	  76
                                 Depth to Water Table Based on Soil Morphology	  79
                                 Three-Dimensional Mapping of Hydraulic Head	  79
                 6.4.4 Wetland Identification and Delineation	  82
                 6.4.5 Floodplain and Other Hydrologic Characterizations	  83
                 6.4.6 Geotechnical Characterization	  83
                                 Identification of Unstable Areas	  84
            6.5  Data Analysis and Interpretation.	  85
                 6.5.1  Identifying Areas of Shallow Ground Water and Ground-Water Flow
                       Net Analysis	,	  85
                 6.5.2  Other  Geotechnical Considerations	'.	  85
                 6.5.3  Special Site Conditions	  87
                 6.5.4  Computer Modeling	  87
            6.6  References	  87
Chapter?  Design
            7.1  Purpose and Scope	  89
            7.2  Regulatory Requirements	  89
                 7.2.1  Part 503	  89
                       7.2.1.1    Collection of Runoff	  90

                                                  vi

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                           Contents (continued)
                                                                                    Page
          7.2.1.2    Collection of Leachate	  9.1
          7.2.1.3    Limitations on Methane Gas Concentrations	  91
          7.2.1.4    Restriction of Public Access	•	  92
          7.2.1.5    Protection of Ground Water	..'	  92
     7.2.2 Part 258	•			92
     7.2.3 State  Rules Applicable to the Disposal of Sewage Sludge			  92
7.3  Permitting Requirements	,	• •	  92
     7.3.1 Federal Permits	,	•	  93
          7.3.1.1    Self-Implementing Nature of the Part 503 Rule	  93
          7.3.1.2    Who Must Apply for a Permit?	•	  93
          7.3.1.3    Who Issues the Permit?		•	  93
     7.3.2 State  and Local Permits	  93
7.4  Design Methodology and Data Compilation		  94
7.5  Design for Monofills, Surface Impoundments, and Piles and Mounds	  96
     7.5.1 Foundation Design	  96
          7.5.1.1     Field Investigation			  96
          7.5.1.2     Foundation Description.		-	  96
          7.5.1.3     Foundation Design	-	 97
                     Settlement and Compression	•	• 98
                     Bearing Capacity	 98
                     Seepage and Hydrostatic Pressures	 98
     7.5.2 Monofill Design	-....-	 98
           7.5.2.1     Trench Designs		•	 99
                     Narrow Trench	 102
                     Wide Trench	,	102
           7.5.2.2    Area Fill Designs	 103
                     Area Fill Mound	 105
                     Area Fill Layer	  105
                     Diked Containment	•	  1ฐ5
     7.5.3 Surface Impoundment and Lagoon Design	  107
           7.5.3.1    Facultative Sludge Lagoons	  107
                     Design Criteria	'	,	  108
           7.5.3.2    Anaerobic Liquid Sludge Lagoons			  112
           7.5.3.3    Sludge Drying Lagoons	  112
                     Design Criteria	• • •	
      7.5.4 Design of Piles and Mounds.	•	•	
      7.5.5 Slope Stability and Dike Integrity	I..'....		  114
           7.5.5.1    Slope Stability Failure	 115
                                       vii

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                            Contents (continued)

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           7.5.5.2    Stability Analyses	-.	  115
                     Subsurface Exploration Program	  115
                     Slope Stability	;	  117
           7.5.5.3    Slope Stability Design Plans	  118
     7.5.6 Liner Systems	,	  118
           7.5.6.1    Low-Permeability Soil Liners	  119
                     Site and Material Selection	  119
                     Thickness	  120
                     Hydraulic Conductivity	  120
                     Strength and Bearing Capacity	  121
                     Slope Stability	  121
           7.5.6.2    Flexible Membrane Liners (FMLs)	  121
                     Performance Requirements of the FML	  121
                     Permeability	  122
                     Mechanical Compatibility	  122
                     Durability	,	'.	  122
                     Selection of the FML	  122
                     Seaming of FML Sheeting	  122
     7.5.7 Leachate Collection and Removal Systems (LCRSs)	  122
           7.5.7.1     Grading and Drainage	  123
                     Granular Drainage Layers and Geosynthetic Drainage Layer-Geonets. .  123
                     Piping	  123
                     The HELP Model	  124
           7.5.7.2    System Strength	  124
                     Sidewall Stability	  124
                     Stability of Drainage Layers	  124
                     Pipe Structural Strength	  124
           7.5.7.3    Prevention of Clogging	  125
           7.5.7.4    Layout of System Components	  125
           7.5.7.5    Leachate Treatment	..'....''.	  126
7.6  Design for Codisposal with Solid Waste	:	  126
     7.6.1  Sludge/Solid Waste Mixture	  126
     7.6.2  Sludge/Soil Mixture and Sludge as Daily Cover Material	  128
     7.6.3  Sludge/Soil Mixture and Sludge as Final Cover Material	  129
7.7  Design Considerations for Dedicated Surface Disposal Sites	  129
     7.7.1  Presence of a Natural Liner and Design of a Leachate Collection System	  129
     7.7.2  No Contamination of Aquifers: Nitrogen Control at DSD Sites	  130
     7.7.3  Methods for Disposal of Sewage Sludge on DSD Sites	  130
                                     VIM

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Contents (continued)
                                                                                  Page

         7.7.3.1    Disposal Methods for Liquid Sludge at DSD Sites	  131
                   Subsurface Methods	
                   Surface Methods.	•	
                   Spray Method	• • • •	
         7.7.3.2    Disposal Methods for Dewatered Sludge at DSD Sites	  135
         7.7.3.3    Disposal Methods Not Recommended	  136
    7.7.4 Sludge Disposal Rates at DSD Sites.	-	• • • • •	  137
    7.7.5 Drying Periods Between Sludge"Spreading Activities		  139
                                                                                    140
    7.7.6 Land Area Needs	•	
         7.7.6.1     Land Needed for Sludge Disposal	• • • •  140
         7.7.6.2     Land Needed for Sludge Storage		•	
         7.7.6 3     Land Needed for Buffer Zone		
    7.7.7 Proximity to Community Infrastructure	  143
    7.7.8 Climate Considerations	
    7.7.9 Design Considerations' At Beneficial DSD Sites.	
7.8  Environmental Safeguards at Surface Disposal Sites	• • •	
     7.8.1 Leachate Controls	•	
     7.8.2 Run-on/Runoff Controls	'..;..'	
          7.8.2.1    Design Overview	
                    Identify Design Storm	-	•	
                    Determining Peak Discharge Rate/Calculating Runoff	  145
                    Control System Structures	•	  145
     7.8.3 Explosive Gases Control	• • • •	
          7.8.3.1    Gas Monitoring	 • •	•	;	
          7.8.3.2    Gas Control Systems	•	
                    Passive Systems	
                    Active Systems	• •	•	
 7.9  Other Design Features		•	
     7.9.1  Access	• • •	• •	•
     7.9.2 Soil Availability	
     7.9.3 Special Working Areas		•	•	
     7.9.4 Buildings and Structures	• •	
     7.9.5 Utilities	•	••; • w • • •	
     7.9.6 Lighting	•	
      7.9.7 Wash Rack	. - • •	: • • •	'	
 7.10 References	
                                                          140
                                                          142
                                                          143
                                                          143
                                                          143
                                                          143
                                                          144
                                                          144
                                                          144
                                                           148
                                                           149
                                                           149
                                                           150
                                                           150
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                                                           153
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                                                           154
             IX

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                                        Contents (continued)
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Chapter 8  Surface Disposal of Domestic Septage
            8.1  Regulatory Requirements for Surface Disposal of Domestic Septage	  157
            8.2  Domestic Septage Disposal Lagoons	                   157
            8.3  Monofills (Trenches) for Domestic Septage Disposal	     158
            8.4  Codisposal at Municipal Solid Waste Landfill Unit	                   158
            8.5  References	                                                       H...,
                                               	  1 oo
Chapters   Operation
            9.1   Purpose and Scope	                     15g
            9.2  Regulations	                                      .. cc.
                                                        	*•••••••••••••*••••••.......  i{?y
                 9.2.1  Part  503.	                       15g
                      9.2.1.1    Management Practices That Affect the Operation of Surface
                                Disposal Sites	              ^gg
                      9.2.1.2    Operational Standards for Pathogen and Vector Attraction Reduction     159
                      9.2.1.3    Other Requirements Under Part 503 Affecting Operation	  160
            9.3   Method-Specific Operational Procedures	             160
                 9.3.1  Operational Procedures for Monofilling	             160
                      9.3.1.1     Trench	 160
                                Site Preparation	                160
                                Sludge Unloading	        161
                                Sludge Handling and Covering	 	 IQ-J
                                Operational Schematics	    161
                     9.3.1.2     Area Fill	'.'.'.'.'.'.'.'.""'" 161
                                Area Fill Mounds	;                    161
                                Area Fill Layer	        163
                                Diked Containment	            164
                                Operational Schematics	      164
                9.3.2 Operational Procedures for Lagoons	            164
                     9.3.2.1    Facultative Sludge Lagoons	    164
                               Start-up and Loading	      164
                               Daily Routine	             ^g4
                     9.3.2.2    Operations for Sludge Drying Lagoons	  164
                9.3.3 Operational Procedures for Codisposal	       166
                     9.3.3.1    Sludge/Solid Waste Mixture	.'!!!  166
                     9.3.3.2    Sludge/Soil Mixture	..."..  167
                     9.3.3.3    Operational Schematics	      167
                9.3.4 Operational Procedures at Dedicated Surface Disposal Sites	 167
                    9.3.4.1    Aesthetics at DSD Sites	           '     167

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                     9.3.4.2    Labor	•	  167
                     9.3.4.3    Operational Considerations at Dedicated Beneficial Use Sites	  169
           9.4  General Operational Procedures	  169
                     9.4.1      Management Practices Required Under Part 503	  169
                     9.4.1.1    Leachate Collection System .	-	  169
                     9.4.1.2    Collection of Surface Water Runoff	  169
                     9.4.1.3    Crop Production and/or Grazing of Animals	  169  .
                     9.4.1.4    Access Restrictions	•	• •  169
                     9.4.1.5    Monitoring Requirements	•'•••'	  169
                     9.4.1.6    Pathogen and Vector Attraction Reduction	  170
                9.4.2 General Operational Procedures for Sewage Sludge  Surface Disposal Sites .....  170
                     9.4.2.1    Environmental Control Practices	  170
                     9.4.2.2    Inclement Weather Practices	  171
                     9.4.2.3    Hours  of Operation	• •	  171
            9.5  Equipment	•	• • • •  ^
            9.6  References	• • •	• •  176

Chapter 10  Monitoring
            10.1 Purpose and Scope	 177
            10.2 Regulatory Requirements	• •	 177
                10.2.1   Part 503 Regulation			 177
                10.2.2  Part 258 Regulations	•	 177
                10.2.3  Other Regulatory Requirements	•	 177
            10.3 General Sampling and Analytical Considerations	 177
                10.3.1   Parameters of Interest	 178
                10.3.2  Media To Be Sampled		 178
                 10.3.3  Sampling Locations	•	-	  178
                 10.3.4  Sampling Frequency			  179
                 10.3.5  Sample Collection and Handling Procedures	  179
                 10.3.6  Sample Analysis Methods		. -	  182
                        EPA-Specified Methods	  182
                        Other Standard Methods	'.	•	  182
                        Field Screening Methods	•  • •	• •	  182
            10.4 Media-Specific Monitoring Considerations	  184
                 10.4.1  Sewage Sludge Characterization	'. -•	• - • • •		  184
                 10.4.2 Ground-Water  Monitoring	•	•	  186
                 10.4.3  Leachate and Surface Water Monitoring	  190
                                                  XI

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                                       Contents (continued)
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                 10.4.4  Monitoring Air for Methane Gas		  191
            10.5 Analysis and Interpretation of Sample Data	  191
                 10.5.1  Sewage Sludge Characterization Data	  191
                 10.5.2  Ground-Water Sampling Data	  192
                 10.5.3  Other Data	                   192
            10.6 References	    192

Chapter 11  Recordkeeping, Reporting, and Management for Surface Disposal
            11.1  General	  195
            11.2  Regulatory Requirements for Recordkeeping	  195
                 11.2.1   Part 503 Recordkeeping Requirements for Owners/Operators of Active
                        Sewage Sludge Units With Liners and Leachate Collection Systems	  195
                        11.2.1.1 Records of Management Practices	  195
                               Endangered or Threatened Species	  196
                               Base Flood Flow Restrictions	  195
                               Seismic Impact Zones	  196
                               Fault Zones	  197
                               Unstable Areas	  197
                               Wetlands	  197
                               Storm Water Runoff	  197
                               Leachate Collection and Control	  197
                               Monitoring Air for Methane Gas	  198
                               Food/Feed/Fiber Crops Prohibition	  198
                               Grazing Prohibition	  198
                               Public Access Restrictions	  198
                               Prohibition of Ground-Water Contamination	 198
                     11.2.1.2   Part 503 Recordkeeping Requirements for Vector Attraction
                               Reduction	 199
                              Option 9—Sewage Sludge Injected Below Surface of the Land	 199
                              Option 10—Sewage Sludge  Incorporated Into the Soil	 199
                              Option 11—Sewage Sludge Covered With Soil or Suitable Material	 199
                     11.2.1.3  Records of Pathogen Reduction	 199
                11.2.2  Part 503 Recordkeeping Requirements for Owners/Operators of Active
                       Sewage Sludge Units Without Liners and Leachate Collection Systems	  199
                11.2.3  Part 503 Recordkeeping Requirements for the  Preparer of Sewage Sludge
                       for Placement on a Surface Disposal Site	  200
                11.2.4  Recordkeeping Requirements for Surface Disposal of Domestic Septage	  200
                11.2.5  Part 258 Recordkeeping Requirements	  200
                11.2.6  Other Recordkeeping Requirements	  200
                                               xii

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                                      Contents (continued)
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           11.3 Cost and Activity Recordkeeping	  201
                11.3.1  General.	•	• • •  201
                11.3.2  Cost Recordkeeping	  201
                11.3.3  Activity Records	•	  202
           11.4 Part 503 Reporting Requirements	: • •  202
                11.4.1  General	•  202
                11.4.2  Reporting Requirements in the Event of Closure		  203
           11.5 Management Organization	  204
                11.5.1  General	  204
                11.5.2  Municipal Operation	  204
                11.5.3  County Operation	".	 -	  204
                11.5.4  Sanitary District Operation		  204
                11.5.5  Private Operation	  204
            11.6 Staffing and Personnel	•	  205
                11.6.1  General	  205
                11.6.2   Personnel Descriptions	  205
                11.6.3  Training  and Safety	  205
            11.7 References	  206
Chapter 12  Closure and Post-Closure Care
            12.1 General	  209
            12.2 Regulatory Requirements —	  209
                12.2.1   Part 503	  209
                12.2.2  Part 258	  209
            12.3 Closure		  210
                12.3.1   Closure  Plan.	•  210
                12.3.2  Cover for Monofills or MSW Landfills	  210
                        12.3.2.1   General	 • • •	  210
                        12.3.2.2  The Infiltration Layer	  215
                                 Geomembranes	  216
                        12.3.2.3  The Erosion Layer	  216
                        12.3.2.4  The Vegetative Cover			  217
                        12.3.2.5  Alternate Final Cover Design			  218
                        12.3.2.6  Other Components for Final Cover Systems	  218
                                 The Drainage Layer	  218
                                 The Gas Venting Layer.			•  218
                                                 XIII

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                                        Contents (continued)
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                                 The Biotic Layer	  219
                       12.3.2.7   Other Design Issues	  219
                                 Hydrology	  219
                                 Settlement	  219
                                 Slope Stability	  220
                 12.3.3 The Stormwater Management System	  220
             12.4 Post-Closure Maintenance	            220
                 12.4.1  Inspection Program	  220
                 12.4.2 Maintenance	                 221
                        12.4.2.1   Stormwater Management System	  221
                        12.4.2.2   Regrading	  221
                        12.4.2.3   Vegetation	  221
                        12.4.2.4   The Leachate Collection System	  223
                        12.4.2.5   Gas Monitoring and Collection System	  223
                        12.4.2.6   Site Access and Security	 223
            12.5 References	                    223
Chapter 13 Costs of Surface Disposal of Sewage Sludge
            13.1 Hauling Costs	                             225
            13.2 Monofills and MSW Landfills	     225
                 13.2.1  Site Costs	          225
            13.3 Dedicated Disposal of Sewage Sludge	          229
            13.4 Cost Analysis	                229
            13.5 References	                          231
Chapter 14  Design Examples
            14.1  Introduction	              233
            14.2 Design Example No. 1	_              233
                 14.2.1  Statement of Problem	                  233
                 14.2.2 Design Data	  233
                       14.2.2.1   Treatment Plant Description	  233
                       14.2.2.2   Sludge Description	  233
                       14.2.2.3   Climate	  234
                       14.2.2.4   General Site Description		  234
                       14.2.2.5   Hydrogeology	  234
                14.2.3  Design	_                  234
                       14.2.3.1   Selecting  a Monofill Type	  234
                       14.2.3.2   Design Dimensions	  234
                                                XIV

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                       14.2.3.3  Site Development	  236
                       14.2.3.4  Calculations	•	  238
                       14.2.3.5  Equipment and Personnel	  238
                       14.2.3.6  Operational Procedures			  238
                       14.2.3.7  Cost Estimates	,	  239
           14.3  Design Example No. 2	•	  24ฐ
                14.3.1  Statement of Problem	  24ฐ
                14.3.2  Design Data	:	  24ฐ
                       14.3.2.1  Treatment Plant Description	  240
                       14.3.2.2  Sludge Description	•	  241
                       14.3.2.3  Climate	• • • •  241
                       14.3.2.4  General Site Description			  24"l
                       14.3.2.5  Hydrogeology	  241
                14.3.3  Design	  242
                       14.3.3.1  Selecting a Monofill Type	  242
                       14.3.3.2  Design Dimensions.	  243
                       14.3.3.3  Site Development	•	  243
                       14.3.3.4  Calculations	  243
                       14.3.3.5  Equipment and Personnel	  244
                       14.3.3.6  Cost Estimates	.,	• •	• • •  244
                       14.3.3.7  Conclusion	• • •:	  245
           14.4 Design Example No. 3	  245
                14.4.1  Statement of Problem	• •	  245
                14.4.2 Design Data	•	  245
                       14.4.2.1   Treatment Plant Description	• • •  246
                       14.4.2.2   Sludge Description	  246
                       14.4.2.3   Climate	  247
                       14.4.2.4   General Site Description	 247
                       14.4.2.5  Hydrogeology	• •	 248
                14.4.3 Design	•	 248
                       14.4.3.1   Selecting a Monofill Type	• 248
                       14.4.3.2  Design Dimensions	 248
                       14.4.3.3  Calculations	• •		• •	 248
                       14.4.3.4  Operational Procedures	•	 248
                       14.4.3.5  Cost Estimates	•	 249

Chapter 15  Case Studies
            15.1 Case  Study 1: Surface Disposal in a Monofill Following Freeze-Thaw
                Conditioning in a Lagoon Impoundment	  251
                                                 xv

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                                        Contents (continued)
                                                                                                Page
                  15.1.1  General Site Information	  251
                  15.1.2  Site Characteristics	  251
                  15.1.3  Domestic Septage Conditioning and Disposal	  251
                         15.1.3.1  Lagoon Design	  251
                         15.1.3.2  Conditioning and Disposal Process	  253
                  15.1.4  Operations Factors	  254
                         15.1.4.1  Sludge Characteristics	  254
                         15.1.4.2  Monitoring	  254
                  15.1.5  Disposal Cell Capacity	  254
             15.2  Case Study 2: Use of a Lagoon for Sewage Sludge Storage Prior to Final Disposal
                  (Lagoon Impoundment in Clayey Soils)	  254
                  15.2.1  General Site Information	  254
                  15.2.2  Design Criteria	  255
                  15.2.3  Sludge Collection and Disposal	  255
                         15.2.3.1   Sludge-Collection Process Steps	  255
                         15.2.3.2  Sludge-Disposal Alternatives	  257
                  15.2.4  Sludge Production Projections	  257
             15.3  Case Study 3: Dedicated Surface Disposal in a Dry-Weather Climate	  257
                  15.3.1  General Site Information	  257
                  15.3.2  Surface Disposal Approach	,	  259
                         15.3.2.1 Process Description	  .........  259
                         15.3.2.2  Character of Sewage Sludge	  259
                  15.3.3  Operation  and Maintenance	  261
             15.4 Case Study 4: Dedicated Surface Disposal in a Temperate Climate	  261
                 15.4.1  General Site Information	  261
                 15.4.2  Design Criteria	  261
                 15.4.3 Treatment and Surface Disposal Approach	  264
                         15.4.3.1   Spring Creek Surface Disposal  Site	,,	  264
                         15.4.3.2   Sugar Creek Surface Disposal Site	  264

Appendix A Permit Application	  267

Appendix B Federal Sewage Sludge Contacts	  269
            EPA Regional Sewage Sludge Contacts	:	  269

Appendix C Manufacturers and Distributors of Equipment for Characterization and
            Monitoring of Sewage  Sludge Surface Disposal Sites	  271
                                                 XVI

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List of Figures
1-1    Generation, treatment, use, and disposal of sewage sludge and domestic septage	 2

1-2   Elements of a Part 503 Standard for surface disposal of sewage sludge or domestic septage	 2

1-3   Part 503 regulatory definitions of sewage sludge and domestic septage	•	 3

1-4   Guide to manual contents	•	''"	

1-5   Technical evaluations involved in implementing a surface disposal project	

2-1   Relationship between active sewage sludge unit and surface disposal site	

2-2   Relationship between active sewage sludge unit and surface disposal site	

3-1   Paint filter test apparatus	•	

4-1    Flow of screening process for site selection	

4-2    Seismic impact zones	•	

 4-3    Wetlands decision  tree for siting active sewage sludge unit	

 4-4   Schematic  representation showing different types of surface area requirements at a sludge
       disposal site	•	

 4-5   Sample calculation of surface disposal site size required for a wide trench operation	 44

 4-6   Sample calculation of surface disposal site size life for a narrow trench operation	 44

 4-7   Soil textural classes and general terminology used in soil descriptions  by the
       U.S. Department of Agriculture	• • •	

 4-8   Soil permeabilities of selected soils	j "

 4-9   Unified soil classification system with characteristics pertinent to surface disposal site	!.

 4-10  Method for estimating site costs	

 4-11  Initial  assessment with  overlays for Study Area X	•	•

  6-1    Site complexity indicators for selection of assessment techniques	

  6-2   Core  sampling with handheld power driver: (a) hammer driver; (b) positioning probe rod jack for
        manually retrieving deep core samples; (c) chuck in down position; (d) pulling position, level
        down	'	
                                                        6

                                                        7

                                                        9

                                                        10

                                                        28

                                                        34

                                                        36

                                                        38


                                                        43
                                                         45

                                                         46

                                                         47

                                                         48

                                                         49

                                                         75
         XVII

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                                           Figures (continued)


                                                                                                   Page

  6-3   Hydraulic probes mounted in van and pickup truck	        73


  6-4   Narrow-diameter borehole grouting procedure using rigid pipe and internal flexible tremie tube	  78

  6-5   Cross-sectional diagram showing depth variations of water level as measured by piezometers lo-
        cated at various depths	                80


  6-6   Ground-water contour surfaces using multilevel piezometer measurements	     80

  6-7   Typical pore pressure sounding diagram for a layered soil; u0 = equilibrium pore pressure	  81

  6-8   Manual piezometer installations methods: .(a) weighted driver; (b) crank-driven	  82

  6-9   Effect of fracture anisotropy on the orientation of the zone of contribution to a pumping well	  86

  6-10   Example flow net construction: Three layers with downward flow	     86

 7-1    Organization of Chapter 7, Design	           90

 7-2   Typical site plan	                  97

 7-3   Trench sidewall variations	;                                 100

 7-4   Cross section of typical narrow trench operation	     102

 7-5   Cross section of typical wide trench operation	;	                102

 7-6   Cross section of typical wide trench operation	               103

 7-7   Wide trench operation	                   103
 7-8    Cross section of wide trench with dikes
                                                                                                   104
 7-9    Cross section of typical area fill mound operation	         106

 7-10   Area fill mound operation	                               106


 7-11   Cross section of typical area fill layer operation	              106


 7-12   Cross section of typical diked containment operation	               10j


 7-13   Comparison of wastewater lagoon and sludge lagoon	     108

 7-14   Schematic representation of an FSL	                     10g

 7-15a  Typical FSL layout	              110


7-15b  Typical FSL cross section	                    H0


7-16   Layout for 124 acres of FSLs: Sacramento Regional Wastewater Treatment Plant	  111
                                                 XVIII

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                                        Figures (continued)
                                                                                                 Page
7-17  Anaerobic liquid sludge lagoons, Prairie Plan land reclamation project, the Metropolitan Sanitary
      District of Greater Chicago ..................... ............. ....... ........ . . ..... - • • •  112

7-18  Plan view of drying sludge lagoon near west-southwest sewage treatment works, Chicago ........  113

7-19  Conceptual slope failure models [[[  116

7-20  Schematic of a single clay liner system for a landfill ................................. • ---- •  119

7-21  Schematic of a double liner and leak detection system for a landfill ....... . ...................  120

7-22  Landfill codisposal ..................... .............................................  127

7-23  Paint filter test apparatus [[[ • • •  127

7-24  Example of minimum final cover requirements .............................................  129
7-25   Tractor and injection unit
                                                                                                  132
7-26  Tank truck with liquid sludge tillage injections		  132

7-27  Tank truck with liquid sludge grassland injectors	•	  133

7-28  Tractor pulled liquid sludge subsurface injection unit connected to delivery hose	  133

7-29a Tank wagon with sweep shovel injectors	  133

7-29b Sweep shovel injectors with covering spoons mounted on tank wagon	-  133

7-30  Splash plates on back of tanker truck	  134

7-31  Slotted T-bar on back of tanker truck	  134

7-32  Venter pivot spray application system	  135

7-33  Traveling gun sludge sprayer	• •

7-34  72 cubic yard dewatered sludge spreader	•	

7-35  Large dewatered sludge spreader	

7-36  Example of disc tiller	

7-37  Example of disk plow	

7-38  Suggested drying days between sludge activities at DSD sites for average soil conditions and peri-
      ods of net evaporation <2 in./mo	
                                                                                                   136

                                                                                                   136

                                                                                                   137

                                                                                                   137

                                                                                                   138

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                                           Figures (continued)

                                                                                                   Page
  7-40  Typical temporary diversion dike	                      145
  7-41  Typical channel design	                         146
  7-42  Typical terrace design	                           146
  7-43  Typical paved chute design	                       147
  7-44  Typical seepage basin design	                                147
  7-45  Typical sedimentation basin design	                          147
  7-46  Typical gas monitoring probe		                         148
  7-47  Passive gas control system (venting to atmosphere)	                  150
 7-48  Example schematic diagram of a ground-based landfill  gas flare	       150
 7-49   Example of a gas extraction well	                     151
 7-50a  Perimeter extraction trench system	                         152
 7-50b  Perimeter extraction trench system	                     152
 7-51   Example of an interior gas collection/recovery system	        ...              153
 7-52  Special working area	                           154
 8-1    Certifications required when domestic septage  is placed in a surface disposal site	  158
 9-1    Narrow trench operation	                        162
 9-2    Wide trench operation at solid waste landfill	                  162
 9-3    Wide trench operation with dragline	                       162
 9-4    Wide trench operation with interior dikes	            ;.                 163
 9-5    Area fill mound operation	                        165
 9-6    Area fill layer operation	                          165
 9-7   Area fill operation inside trench	                       165
 9-8   Diked containment operation		                          166
9-9   Sludge/solid waste mixture operation	                     168
9-10  Sludge/solid waste mixture with dikes...                                                        -,CQ
                                                   	  1 DO
                                                  XX

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                                        Figures (continued)
                                                                                                Page
9-11   Sludge/soil mixture	•	•	  168
9-12  Scraper	•	•	  174
9-13  Backhoe with loader	•	  174
9-14  Load lugger	  175
9-15  Trenching machine			  175
10-1  Flow diagram of monitoring system design	•	•  188
10-2  Guidelines for background well sampling based on number of wells	  189
10-3  Micro Well schematic diagram; standard pipe is 0.62 inches internal diameter and 0.82 inches
      outer diameter	
11-1  Certification statement required for recordkeeping: Owner/Operator of surface disposal site.	 196
11-2  Certification statement required for recordkeeping: Preparer of sewage sludge placed on surface
      disposal site	,	•	• 20ฐ
11-3  Certifications required when domestic septage is placed in a surface disposal site		 202
11-4  Monthly activity form	•	 203
11-5  Daily waste receipt form	•	 205
11-6  Equipment inspection form	 206
 11-7  Safety checklist	 207
 12-1  Outline of sample closure and post-closure plan	— •	 211
 12-2  Example  of final cover with hydraulic conductivity (K) < K of liner		....... 215
 12-3a Example  of final cover design for an MSWLF unit with an FML and leachate                  ,
       collection system	.	 216
 12-3b Example  of final cover design for an MSWLF unit with a double FML and leachate
       collection system	 • • • • • • • • •....... • ••'•'•• • • - •	 216
 12-4  Soil erosion due to slope	•	•	'•'•"	• • • •	 2^7
 12-5  Example of alternative final cover design incorporating other components that may be used in final
                                                                                                  P1Q
       cover systems	  ^l57
 12-6  Thickened cover for tolerance of settlement	.••'•"•  221
 12-7  Typical elements of maintenance program	  222
                                                  xxi

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                                        Figures (continued)

                                                                                              Page
 13-1  Typical costs for hauling dewatered sludge	          226
 13-2  Capital costs for sludge monofills and MSW landfills	   226
 13-3  Operating costs for sludge monofills and MSW landfills.	 227
 13-4  Total costs for sludge monofills and MSW landfills	          227
 13-5  Capital costs for dedicated surface disposal site	             230
 13-6  O&M costs for dedicated surface disposal site	                  231
 13-7  Total costs for dedicated surface disposal site	         232
 14-1   Plan view of site in example number 1	                 235
 14-2  Site development plan for example number 1	        237
 14-3  Operational procedures for example number 1			                     239
 14-4  Site base map for example number 2	.'.                        242
 14-5   Site development plan for  example  number 2 area fill mound	              244
 14-6   Site development plan for  example number 2 wide fill trench	                245
 15-1  Anderson septage lagoon	                  252
 15-2  Site map of Anderson septage  lagoon	             253
 15-3  Site of  proposed lagoon cells	                                255
 15-4  Topographic map of Hanna Ranch area	                  259
 15-5  Spring Creek disposal site	     _                  262
15-6  Sugar Creek disposal site	                          26g
 B-1   Map of  US EPA Regions	                     270
                                               XXII

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                                           List of Tables
1-1    Types of Sludge, Septage, and Other Wastewater Solids Excluded From Coverage
      Under Part 503	•
1-2   Compliance Dates for Part 503 Requirements	  4

2-1   Comparison of Sludge and Site Conditions for Various Active Sewage Sludge Units	  12

2-2   Design Criteria for Various Active Sewage Sludge Units	  13

3-1   Effects of Sludge Treatment Processes on Sewage Sludge Surface Disposal	  22

3-2   Chemical and Physical Characteristics of Domestic Septage	  23

3-3   Frequency of Monitoring for Surface Disposal Under Part 503	• • •  24

3-4   Methods Required by Part 503 for the Analysis of Metals in Sewage Sludge Placed on a Surface
      Disposal Site	• • •	

3-5   Part 503 Pollutant Limits for Sludge Placed on a Surface Disposal Site ...	...	...
24

25
 3-6    Processes to Significantly Reduce Pathogens (PSRPs) Listed in Appendix B of 40 CFR
       Part 503	••••	•;;••••	••••••  26

 3-7    Summary of Requirements for Vector Attraction Reduction Under Part 503	  27

 3-8    Applicability of Options for Meeting the Vector Attraction Reduction Options  Under Subpart D..	  28

 3-9    Toxicity Characteristic Constituents and Regulatory Levels	  29

 4-1    Part 503 Subpart C Management Practices Influencing Siting of an Active Sewage Sludge Unit  ...  33

 4-2    Summary of Methods for Collecting Data from the Subsurface	  40

 4-3    Surface Disposal Site Selection Criteria	  41

 4-4    Soil Saturated Hydraulic Conductivity and Permability Classes	'.	• •  45

 4-5    Exclusionary and Low Suitability Criteria for Sewage Sludge Surface Disposal Sites	  48

 4-6    Exclusionary and Low Suitability Criteria for Codisposal Sites	  49

 4-7    Preliminary Investigations for Initial Assessment of Study Are X	• • • 50

 4-8   Use of Quantitative Approach to Score Four Candidate Sites for Study Area X	 52

 4-9   Capital Cost Estimates for Four Study Area X Candidate Sites.	 54
                                                  XXIII

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                                           Tables (continued)


                                                                                                  Page

 4-10  Operating Cost Estimates for Four Study Area X Candidate Sites	 55

 4-11  Final Site Selection.	      55

 5-1   Potential PPP Participants	 58

 5-2   Relative Effectiveness of Public Participation Activities	 59

 5-3   Suggested Timing of Public Participation Activities for Sample 30-Month
       Landfill Project	,	         g3

 6-1   General Information Sources	?	 57

 6-2   Topographic Data Sources	 68

 6-3   Aerial Photography and Remote Sensing Sources	i	        69

 6-4   Soils, Geologic, Geophysical, and Geotechnical Data Sources	 70

 6-4   Soils, Geologic, Geophysical, and Geotechnical Data Sources (continued)	 71

 6-5   Types of Data Available on SCS Soil Series Description and Interpretation Sheets	 72

 6-6   Hydrologic, Wetland, and Climatic Data Sources	  72

 6-7   Guide to Major Recent References on Environmental Field Investigation Techniques	  74

 7-1    Sewage Sludge Surface Disposal Site Design Checklist	  95

 7-2   Design Considerations for Trenches	                        99

 7-3   Alternative Design Scenarios	                   101

 7-4   Design  Considerations for Area Fills	  104

 7-5    Design  Criteria for Sludge Storage Basins: Sacremento (California) Regional
       Wastewater Treatment Plant	  H2

 7-6    Advantages and Limitations of Faculative Sludge Lagoons and Anaerobic Lagoons	  113

 7-7    Design Criteria for Drying Lagoons	;             114

 7-8    Advantages and Disadvantages of Using Sludge Drying Lagoons	  115

 7-9    Recommended Minimum Values of Factor of Safety for Slope Stability Analyses	  116

7-10   Minimum Data Requirements for Stability Analysis Options	:.,..,.	 -\-\Q

7-11   Methods for Testing Low-Permeability Soil Liners	        ;21


                                                 xxiv

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                                        Tables (continued)
                                                                                               Page

7-12  Polymers Currently Used in FMLs for Waste Management Facilities		-	 123

7-13  Design Considerations for Codisposal Operations	• •	• •	
7-14  Various Average Leachate Values for Codisposal, Refuse-Only, and Sludge-Only Test
      Cells Averaged Over 4 Years	
                                                                                                128
7-15a Surface Spreading Methods and Equipment for Liquid Sludges		'• •• • •ง • "•	  131

                                                                                    	  131

7-16  Net Monthly Soil Evaporation at Colorado Springs, Colorado		• • • •	•  139
7-15b Subsurface Spreading Methods, Characteristics, and Limitations for Liquid Sludges
      for Liquid Sludge		•	
                                                                                                 139

                                                                                                 143
7-17  Monthly Sludge Disposal Rates at Colorado Springs, Colorado, DSD Site.	• • • •

7-18  Advantages and Disadvantages of Dedicated Beneficial Use Sites	••••••

7-19  Surface Water Diversion and Collection Structures	•	•	  145

9-1.  Environmental Control Practices		'.:..•:•	

9-2   Inclement Weather Problems and Solutions	•  • • • •	•••'••

9-3   Equipment Performance Characteristics	.....:...,	• •	

9-4   Typical Equipment Selection Schemes	:	•  • • • • • • • •	

 10-1  Chemical and Physical Parameters Typically Determined for Monitoring of Sewage Sludge Applica-
      tion Sites	•	;	

 10-2  Frequency of Monitoring for Surface Disposal of Sewage Sludge	'•••••  179
                                                                                                 170

                                                                                                 172

                                                                                                 173

                                                                                                 173
                                                                                                  181
 10-3  Sampling Points for Sewage Sludge  	•		•

 10-4  Minimum Frequency of Monitoring for Surface Disposal of Sewage Sludge	• •  183

 10-5  Comparison of Selected Field Analytical Methods Potentially Applicable for Field Screening
       at Sewage Sludge Surface Disposal Sites (all detection limits  in ppm)	• • • •  183
                                                                                                  185
  10-6  Analytical Methods for Sewage Sludge	•

  10-7  Tabulated Values of Constant T for Evaluating Sludge for 90 Percent Confidence Interval	  186

  10-8  Alternative Values for Calculating Required Number of Sludge Samples for Metals Monitoring	  187

  11-1  Certification Statement Required for Recordkeeping: Owner/Operator of Surface Disposal Site	  201
  12-1   Checklist for Surface Disposal Site Inspection
                                                                                                  222
                                                  xxv

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                                         Tables (continued)
                                                                                              Page
 13-1   Cost Scenarios for Alternative Landfilling Methods	  228

 14-1   Estimate of Total Site Capital Costs for Example Number 1	  240

 14-2   Estimate of Annual Operating Costs for  Example Number 1	  240

 14-3   Design Considerations for Example Number 2	  243

 14-4   Estimate of Total Site Capital Costs for Example Number 2 Wide Trench	 	  246

 14-5   Estimate of Annual Operating Costs for  Example Number 2 Wide Trench	  246

 14-6   Estimate of Total Site Capital Costs for Example Number 2 Area Fill Mound		  247

 14-7   Estimate of Annual Operating Costs for Example Number 2 Area Fill Mound	  247

 14-8   Estimate of Total Annual Cost for Example Number 3	  249

 15-1  Sludge Monitoring Parameters	    254

 15-2  Laboratory Permeability Test Results	  255

 15-3  Sewage Sludge Projections	  258

 15-4  1993 Biosolids Monitoring Results	  260

 15-5  PSRP Minimum Temperatures for Anaerobic Digestion	  261

 15-6  Annual Pollutant Loading Rates at the Spring Creek Facility	  264

 15-7  Annual Pollutant Loading Rates at the Sugar Creek Facility	  265

C-1   Manufacturers and Distributors of Equipment for Characterization and Monitoring of Sewage Sludge
      Surface Disposal Sites	                        271

C-2   Addresses and Telephone Numbers of Manufacturers and Distributors	  272
                                               XXVI

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                                 Acknowledgments
There were four groups of participants involved in the preparation of this manual: (1) the contractor,
(2) the technical directors, (3) the technical reviewers, and (4) individuals who provided case studies.
The contractor for this project was Eastern Research Group (ERG), Inc., of Lexington, Massachu-
setts. Technical direction was provided by James E. Smith, Jr., of the U.S. Environmental Protection
Agency (EPA) Center for Environmental Research Information (CERI) in Cincinnati, Ohio.-The
technical reviewers had  expertise in surface  disposal of  sewage sludge and  in the Part 503
regulations, and included government officials, engineering consultants, and equipment manufac-
tures. Case studies were provided by federal employees with day-to-day experience working oh
sewage sludge disposal issues  and by municipal officials responsible for the  management of
sewage sludge and domestic septage disposal sites. The membership of each group is listed below.
Manual Preparation

Eastern Research Group:
Paula Murphy
Jan Connery
Russell Boulding
Heidi Schultz
 Technical Review

 James J. Walsh, SCS Engineers, Cincinnati, OH
 Robert Southworth, OW/OST, EPA, Washington, D.C.
 Robert Brobst, EPA Region 8, Denver, CO
 John Walker, OWM, EPA, Washington, D.C.
 Ash Sajjad,  EPA Region 5, Chicago, IL
 Jeffrey Farrar, Bureau of Reclamation, Denver, CO
 Samuel Kincaid, Geoprobe Systems, Salina, KS
 Jim Pisnosi, Solinst Canada Ltd., Glen Williams, Ontario
 Allan McNeill, McNeill International, Mentor, OH
 Charles Shannon, Hogentogler & Co., Inc., Columbia, MD
 Al Sutherland, EM Science, Gibbstown, MD
 Jim Pine, Pine & Swallow Associates, Groton, MA
 Case Studies

 Robert Brobst, EPA Region 8, Denver, CO
 Kris McCumby, Alaska Department of Environmental Protection
 Gerald L. Peters, Metro Sanitary District, Springfield, Illinois
 Victoria Card, Domestic Water Treatment Facility, Colorado Springs, Colorado
 Glenn Odom, Mississippi Department of Environmental Quality
 Doug Poage, Engineer for Anderson, Alaska
 Dennis R. Dunn, Massachusetts Department of Environmental Protection, Boston, MA
                                          XXVII

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                                              Chapter 1
                                            Introduction
Human domestic activities generate wastewater that
is  piped  into municipal sewer systems, underground
septic tanks, or portable sanitation devices. Wastewater in
municipal systems is treated before being discharged
into the environment, as required under the Clean Water
Act. This cleansing process generates a solid, semi-solid, or
liquid residue—sewage sludge—which must be used or
disposed (see Figure 1-1). Similarly, domestic septage—
the solid, semi-solid, or liquid material that collects in
septic tanks or portable sanitation devices that receive
only domestic septage—must be periodically pumped
out and used or disposed (see Figure 1-1).

Sewage  sludge and domestic septage may be applied
to the land as a soil conditioner and partial fertilizer, incin-
erated, or placed on land (surface disposal). Placement
refers to the act of putting sewage sludge on an active
sewage sludge unit1 at high rates forfinal disposal rather
than using the organic content in the sewage sludge to
condition the soil or using the nutrients in the  sewage
sludge to fertilize crops. This manual provides practical
guidance on the surface disposal approach to managing
sewage sludge and domestic septage.2 The manual:

•  Describes the various types of active sewage sludge
   units.

•  Provides guidance in selecting the most appropriate
   type of  active sewage sludge unit for a particular
   situation.

•  Details the engineering aspects of designing and op-
   erating a surface disposal site.

•  Describes the applicable federal regulations.

The manual is intended for owners and operators of
surface disposal sites, municipal officials involved in sew-
age sludge management, planners, design engineers, and
regional, state, and local governments concerned with
permitting and enforcement of federal sewage sludge
management regulations.
1.1   Regulatory Overview

Most surface disposal of .sewage sludge and domestic
septage is subject to one of two sets of federal regulations,
depending on whether the sewage sludge or domestic
septage is disposed with or without household waste:

• Sites  on which only sewage sludge, domestic sep-
  tage,  or a material derived from sewage sludge3 are
  disposed, are  regulated under Subpart C of 40 CFR
  Part 503.

• Codisposal of sewage sludge/domestic septage and
  household waste at a municipal solid waste (MSW)
  landfill4 is regulated under 40 CFR Part 258.

This manual focuses  on surface disposal sites subject
to the 40 CFR Part 503 and on landfill units subject to
Part 258 regulations.  It explains the regulatory require-
ments for these sites or units and provides guidance on
how these requirements influence selection, design, and
operation of these sites or units. A complete discussion
of the Part 258 regulations is beyond the scope of this
manual. Instead, the Part 258 regulations are discussed
specifically in regard  to their impact on the codisposal
of sewage sludge in municipal solid waste landfill units.
For a more complete discussion of the Part 258 regula-
tions the reader is referred to U.S.  EPA, 1993.

Subpart G of Part 503 includes requirements for sewage
sludge, including domestic septage, placed on a surface
disposal site. Placing sewage  sludge or domestic sep-
tage in a monofill, in a surface impoundment, on a waste
pile, on a dedicated disposal site (DOS), or on a dedi-
cated beneficial  use site is considered surface disposal.
A Part  503 standard for  surface  disposal of sewage
sludge or domestic septage includes seven elements—
general  requirements,  pollutant limits,  management
practices, operational standards, and requirements for
the frequency of monitoring, recordkeeping, and report-
ing, as  shown in Figure 1-2.
 1 A sewage sludge unit is land on which only sewage sludge is placed
 for final disposal. An active sewage sludge unit is a sewage sludge
 unit that has not closed.
 2 U.S. EPA (1994), (1984a), (1984b), (1983), and (1979) provide guid-
 ance on land application and incineration.
 3 For example, a mixture of sewage sludge with nonhazardous solids
 (except for household waste), such as grit, screenings, commercial
 septage, and industrial sludge.
 4 Under Part 258, a municipal solid waste landfill is defined as a landfill
 that receives household waste and that may receive other nonhazard-
 ous waste.

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  SEWAGE SLUDGE
           DOMESTIC
           SEWAQE
                                                                     SEWAGE $LUDQE
                                                                     TREATMENT
                                                                     • Drying
                                                                     • Gocnposling
                                                                      •HMllrMlmwit
                                                                      Eta.
                                                                                         •Land Application
                                                                                          Agricultural land
                                                                                          Strip-mined land
                                                                                          Forests
                                                                                          Plant nurseries
                                                                                          Cemeteries
                                                                                          Parks, gardens
                                                                                          Lawns and home gardens
                       •CUSTOM.
                       WASTSWATER
                       OBERATION
                  •Incineration
                  •Surface disposal
                  •Part 258 Landfill
DOMESTIC SEPTAGE
   SEPTIC TANKS
RAW
SEPTAGE^
NG
COTREATMENT
WITH
WASTEWATER
AND/OR
SEWAGE SLUDGE
                             AND
                            HAULING
                                                SEPTAGE
                                               TREATMENT
                                                                       TREATED
                                                                       SEWAGE
                                                                       SLUDGE/
                                                                       SEPTAGE
Figure 1-1.  Generation, treatment, use, and disposal of sewage sludge and domestic septage.
                               Reporting
                             Requirements
                       Recordkeeping
                       Requirements
                             Frequency
                            of Monitoring
                            Requirements
                                                 General
                                               Requirements
 Surface
Disposal of
 Sewage
 Sludge or
 Domestic
 Septage
                                               Management
                                                 Practices
              Pollutant Limits
               (for Sewage
               Sludge Only)
Operational Standards

   i           J
                    Pathogen       Vector
                     Control      Attraction
                   (for Sewage    . Reduction
                  Sludge Only)
Figure 1-2.  Elements of a Part 503 Standard for surface disposal of sewage sludge or domestic septage.

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Figure 1-3 provides the Part 503 regulatory definition of
sewage sludge and domestic septage. Materials that do
not meet these definitions, as well as certain  sludges
that contain substances of a hazardous nature, are not
covered  by the  Part 503  regulation.  Sites  accepting
these  materials  must  meet other regulatory  require-
ments. Table  1-1 summarizes the Part 503 exclusions
and indicates what  other  regulations sites  accepting
these  materials must meet. Sites that accept mixtures
of sewage sludge and nonhazardous solids other than
household waste  (e.g.,  grit,  screenings, commercial
septage, and  industrial sludge) must meet the Part 503
regulation if these  materials are mixed before they are
placed on the site.  If these materials are not mixed
before they are placed, sites may be subject to both the
Part 503 regulation and the additional requirements listed
in Table 1-1 for the non-sewage  sludge component.

As Table 1-1  indicates, Part 503 does not cover com-
mercial or industrial  septage. The specific definition of
domestic septage  in the Part 503  regulation does not
include many of the other materials that are often called
septage by industry. Commercial and industrial septage
are not considered domestic septage. The factor that
differentiates  commercial and industrial  septage from
domestic septage  is  the type of  waste being produced,
rather than the  type of establishment generating the
waste. For example, the sanitation waste residues and
residues from food  and normal dish  cleaning from a
restaurant are domestic septage, whereas grease trap
wastes from a restaurant are not domestic septage.

While some  of  the  design and operation  information
contained in this manual may be relevant to operations
accepting sludge and septage excluded under Part 503,
this manual provides no information on pertinent regu-
lations concerning these operations. Designers, owners,
and operators of these  sites are encouraged to thor-
oughly research the applicable regulatory requirements.
The  manual  also  does  not  cover land  application  of
sewage sludge  or domestic septage. These practices
are regulated under  Subpart B of 40 CFR Part 503.
                                        Table 1-1. Types of Sludge, Septage, and Other Wastewater
                                                 Solids Excluded From Coverage Under Part 503
 Sewage sludge:
A solid, semi-solid, or liquid residue generated
during the treatment of domestic sewage in a
treatment works. Sewage sludge includes, but
is not limited to domestic septage; scum or
solids removed in primary, secondary, or
advanced wastewater treatment processes; and
a material derived from sewage sludge.

Either liquid or solid material removed from a
septic tank.-cesspool, portable toilet, Type 111
marine sanitation device, or similar treatment
works that receives only domestic sewage.
(Domestic sewage is defined as waste and
wastewater from humans or household
operations.)
 Figure 1-3.  Part 503 regulatory definitions of sewage sludge
            and domestic septage.
 Domestic septage:
                                        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 (see Chapter 3 for further
                                        definition of these materials)

                                        Commercial septage (e.g., grease
                                        from a grease trap at a restaurant)
                                        and industrial septage (liquid or solid
                                        material removed from a septic tank
                                        that receives industrial wastewater)

                                        Industrial sludge and sewage sludge
                                        generated at an industrial facility
                                        during the treatment of industrial
                                        wastewater combined with domestic
                                        septage
                                        Drinking water sludge generated
                                        during the treatment of either surface
                                        water or ground water used for
                                        drinking water.
                                                                         40 CFR Parts 260-268
                                 40 CFR Part 761
                                 40 CFR Part 257a
                                 40-CFRPart257a
                                 40 CFR Part 257 and
                                 any other applicable
                                 requirements depending
                                 on the characteristics of
                                 the mixture3 •• '     ;

                                 40 CFR Part 257a
                                        a Regulated under 40 CFR Part 258 if placed in an MSW landfill for
                                        final disposal.                         .
Certain practices also are specifically excluded from
coverage under the Part 503 regulation. For example,
Part 503 does not cover any operations,  such as la-
goons or stabilization ponds, that are considered to be
a form of sewage sludge treatment rather than use or
disposal. Similarly, Part 503 does not cover any sewage
sludge  storage operation, defined  as any operation
where sewage sludge that  is placed  on the  land, re-
mains on the land for no longer than 2 years. Owners or
operators of a site where sewage sludge remains on the
land longer than 2 years are not subject to the Part 503
surface disposal  requirements if they demonstrate that
the site is not an active sewage sludge unit. The dem-
onstration must include the following information:

• The name and address of the person who  prepares
  the sewage sludge.5

• The  name and  address  of the person  who either
  owns the land or leases the land.
 5 Part 503 defines the 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." This definition covers two types of
 operations—those that generate sewage sludge and those that take
 sewage sludge after it has been generated and blend or mix it with
 another material to further process or prepare it before its ultimate
 use or disposal.

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• The location, by either street address or latitude and
  longitude, of the land.
• An explanation of why sewage sludge needs to re-
  main on the land for longer than 2 years prior to final
  use or disposal, or why the land is used for longer
  than 2 years to store individual batches of sewage
  sludge, on a continuous basis, for less than two years
  (e.g., land is used to store individual batches of sew-
  age sludge for six months out of every year).

• The approximate time when sewage sludge will be
  used or disposed.

This information must be retained by the person who
prepares the sewage sludge for the period  that  the
sewage sludge remains  on the land.

1.2   Compliance and Enforcement of the
      Part 503 Rule

Compliance deadlines  under the Part 503 rule vary
according to the type of requirement (e.g., compliance
dates for frequency of monitoring and for recordkeeping
and reporting requirements differ from compliance dates
for other requirements) and whether new pollution con-
trol facilities will have to be constructed to meet  the
requirement. Compliance dates for all  Part 503 require-
ments are provided in Table 1-2.

Table 1-2.  Compliance Dates for Part 503 Requirements
Part 503 Requirement                   Compliance Date

Land Application and Surface  Disposal Initial   July 20
monitoring and recordkeeping
All other requirements when construction of    As expeditiousiy
new pollution control facilities Is not needed    as possible
to meet requirements
All other requirements when construction of    As expeditiousiy
new pollution control facilities is needed to     as possible
meet requirements
To ensure compliance with Part 503, regulatory authori-
ties have the right to inspect operations involved in the
use or disposal of sewage sludge or domestic septage;
review and evaluate required reports and records; sam-
ple sewage sludge or domestic septage; and respond to
complaints from persons affected by an alleged im-
proper use or disposal of sewage sludge or domestic
septage. If records are not kept or other Part 503 re-
quirements are not met, U.S.  EPA can initiate enforce-
ment actions.

Violations of the Part 503 requirements are subject to
the same sanctions as wastewater effluent discharge
violations—U.S.  EPA can sue in civil court and seek
remediation and penalties, and it can prosecute willful
or negligent violations as criminal acts.
1.3   Relationship of the Federal
      Requirements to State Requirements

Part 503 does not replace any existing state regulations;
rather, it sets minimum national standards for the use
or disposal  of  sewage  sludge or domestic septage
through certain  use or disposal  practices.  In some
cases, the state requirements may be more restrictive
or administered in a manner different from the federal
regulation. In all cases, persons wishing to use or dis-
pose of sewage sludge or domestic septage must meet
all applicable requirements. Readers are encouraged to
thoroughly investigate the relevant state  requirements
as one of the first steps in decision-making about any
surface disposal site.

Knowing exactly which state or federal rules to follow
can sometimes be complicated. Users or disposers of
sewage sludge or domestic septage should  keep the
following situations in mind when considering the appli-
cability of requirements:

• In all cases, users or disposers of sewage sludge or
  domestic septage  must comply with the requirements
  of the Part 503 rule, assuming of course that the use
  or disposal practice is not otherwise excluded from
  coverage under Part 503.

• If a state  has its own rules  governing the use  or
  disposal of sewage sludge or domestic septage and
  has not yet adopted the federal rule, the owner/op-
  erator of the surface disposal site will have to follow
  the  most restrictive portions of both the federal and
  state  rules.

It is important to note that sewage sludge or domestic
septage may be defined differently by state programs
than in the Federal Part 503 rule. Users or disposers of
sewage sludge or domestic septage are strongly encour-
aged to check with the appropriate state sewage sludge
coordinator regarding the specific state requirements.

1.4   How To Use This Manual

The manual consists of 15 chapters and 3 appendices:

• Chapter 2 defines and reviews the various types of
  active sewage sludge  units.

• Chapter 3 describes characteristics of sewage sludge
  and domestic septage that influence the suitability of
  sewage sludge or  domestic septage for particular ac-
  tive sewage sludge units.

• Chapter 4 reviews the regulatory requirements and
  technical parameters  that influence site  selection,
  and presents a process that can be used  to select
  the  most appropriate site for surface disposal.

• Chapter 5 describes why, when, and how to involve
  the  public  in the site selection process.

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• Chapter  6 reviews the various techniques  for field
  investigation that  provide  valuable  information for
  both site selection and design.

• Chapter 7 provides guidance on the design of active
  sewage sludge units and surface disposal sites.

• Chapter 8 specifically discusses surface disposal of
  domestic septage.

• Chapter 9 provides guidance on the operation of ac-
  tive sewage sludge units and surface disposal sites.

• Chapters 10, 11, and 12 discuss: monitoring; manage-
  ment, recordkeeping and reports; and, closure and post-
  closure care at surface disposal sites.

• Chapter 13 provides typical costs for surface  disposal
  sites.

• Chapters 14 and  15 include  design  examples and
  case studies to illustrate the application of the generic
  principles to specific situations.

• Appendix A provides guidance on what information
  to include in a permit application.

• Appendix B provides contact information for EPA re-
  gional sewage sludge coordinators.

• Appendix C provides information on manufacturers
  and distributors  of equipment for monitoring at sew-
  age sludge  surface disposal sites.

Figure 1-4 shows the relationships of the various chap-
ters. Regulatory information on the seven elements of a
Part 503 standard  (see Figure 1-2) is included  through-
out this manual as the requirements  of each  element
affect specific aspects of  designing a surface  disposal
site. For example, management practices regulating
the siting of surface disposal  sites are discussed in
Chapter 4, Site Selection; whereas, management  prac-
tices regulating the design of drainage systems at sur-
face disposal sites are discussed in Chapter 7, Design.
Readers seeking to determine whether surface disposal
is a viable option or which type of active sewage sludge
unit might be most appropriate for a particular situation
are advised to read Chapters 1 through  13. Readers
who already have determined the type of active sewage
sludge unit to use and seek guidance on selecting an
appropriate location for a surface disposal site may wish
to focus on Chapters 4, 5, and 6, as well as the sections
of Chapters 7 and 9 relevant to the particular active
sewage sludge unit selected. Readers seeking guidance
on the surface disposal of domestic septage will find this
information in Chapter 8. Figure 1-5 gives an overview
of the technical evaluations involved in implementing a
surface disposal project  and outlines relevant chapters
of the manual to consult when considering the different
phases involved in this implementation process.

1.5    Use of the Terms "Sludge" and
       "Septage" in This Manual

For simplicity's sake, subsequent chapters of this man-
ual use the term "sludge" to mean sewage sludge as
defined under Part 503 (i.e., including domestic sep-
tage), unless otherwise stated. Similarly the manual
uses  the term "septage" to mean only domestic septage
and not commercial or industrial septage.

1.6    References
.1. U.S. EPA. 1994. Process design manual: Land application of
  municipal sewage sludge and domestic septage. [Currently being
  prepared]
2. U.S. EPA. 1993. Solid waste disposal facility criteria: Technical
  manual. EPA/530/R-93/017 (November).
3. U.S. EPA. 1984a. Use  and disposal of municipal wastewater
  sludge. EPA/625/10-84/003. Cincinnati, OH.
4. U.S. EPA. 1984b. Handbook: Septage  treatment and disposal.
   EPA/625/6-84/009. Cincinnati, OH.
5. U.S. EPA. 1983. Process design manual for land application of
  municipal sludge. EPA/625/1-83/016 (October).
6. U.S. EPA. 1979. Process design manual: Sludge treatment and
  disposal. EPA/625/1-79/011. Cincinnati, OH.

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                                       I  Chapter 1. Introduction

t
Chapter 2. Surface Disposal Practices
t
Chapter 3. Characteristics of Sewage
Sludge and Domestic Septage

t
Chapter 4. Site Selection

t
| Chapter 5. Public Participation

t
| Chapter 6. Field Investigations




Design for Sewage Sludc
Regulated Ui
1
Mono Surface Pile
fill Impoundments anc





t
)ter 7. Design (use appropriate sections)



|

e Surface Disposal Sites
>der Part 503
I I
s Dedicated Dedicated
Disposal Beneficial
unds Sites Use Sites
Design for Sewage Sludge
Disposal Site
Regulated Under Part 258
Codisposal

| 	 - 	 1 	 - 	
1

1
Chapter 8. Surface Disposal of Domestic Septage [

t
1 Chapter 9. Operation

*
1 Chapter 1 0. Monitoring

t

Chapter 1 1 . Management, Recordkeeping, and Reports

t
I Chapter 12. Closure and Post-Closure Care

t
I Chapter 13. Costs

t
Chapter 14. Design Examples

t
Chapter 15. Case Studies

Figure 1-4.  Guide to manual contents.

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                            Preliminary Planning Phase (see Chapters 3 and 5)
                        Evaluate Public Sentiment and Formulate a Public Participation Program
    Determine Sewage" Sludge Characteristics
       ^—Data Gathering-____^
                I           ^^ Determine Federal, State and Local
               V               Regulatory Requirements
Determine Sewage3 Sludge Quantities
                          Compare Sewage Sludge8 Characteristics to Regulatory Requirements and
                                 Evaluate Suitability of Sewage Sludge8 for Surface Disposal
                                    Site Selection Phase (see Chapter 4)
                                      Review Regulatory Siting Requirements
                                 Calculate Land Area Required For Desired Site Life
                                       'Availability of Land Area Necessary>
      Assess Sludge Transportation
      Modes and Distance to Site
Evaluate Site Physical Characteristics
Determine Land Acquisition
Probability and Cost
                                   Select Alternate Sites for Further Investigation
                                      Site Design Phase (see Chapter 7)
                         Identify Design Requirements for Chosen Active Sewage Sludge Unit:
                                            Physical and Regulatory
      Foundation Requirements, Liner Systems, and
      Leachate Collection Systems (if installed),    -ซ
      Climatic Considerations
                          Perform Detailed Field Investigation:
                          Physical Features, Topography, Depth
                          to Groundwater, and Soil Conditions
              Design Filling Area, or Determine Annual Disposal Rates and Land Requirements for DSD Sites
                 Design Environmental Safeguards, Runon/Runoff Controls and Explosive Gases Control
                       Operation and Maintenance Phase (see Chapters 9,10, and 11)
        Develop a Recordkeeping and Reporting
        Program in line with Regulatory Requirements
                        Schedule Operation to Satisfy Chosen Active
                        Sewage Sludge Unit and Schedule
                        Monitoring Requirements
         8 Including domestic septage.

Figure 1-5. Technical evaluations involved in implementing a surface disposal project.

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                                              Chapter 2
                                  Active Sewage Sludge Units
2.1   Introduction

A sewage sludge unit  is land on which only sewage
sludge is placed for final disposal. This does not include
land on  which  sewage sludge  is  either stored or
treated. An  active sewage sludge  unit is a sewage
sludge unit that has not closed. A surface disposal site
is an area of land  that contains one or more active
sludge units. Figure 2-1 illustrates the relationship be-
tween active sewage sludge  units and a surface dis-
posal site.

This chapter discusses  the various types of active sew-
age sludge units and surface disposal sites, and com-
pares the basic sludge and site requirements and design
criteria of each unit so that the reader can assess which
unit(s) may be most appropriate for a particular situation.
The active sewage sludge units discussed in this chap-
ter  include  monofills,  surface impoundments, waste
piles, dedicated surface disposal sites, and dedicated
beneficial use sites  (see Figure 2-2). There are no dif-
ferences between any  of these active sewage sludge
units from a regulatory perspective. Each of these units
                               Surface Disposal Site
                        Active Sewage     i
                        Sludge Unit
must meet all of the requirements of the Part 503 regu-
lation. The differences between these units outlined in
this chapter are based on design criteria and good
engineering practice.This chapter also discusses the op-
tions for codisposing sewage sludge in a municipal solid
waste. (MSW) landfill.

Selection of an active sewage sludge  unit is an integral
part of the site selection process because the accept-
ability of a given surface disposal site depends on how
the sewage sludge is disposed. Conversely, the accept-
ability of a given active sewage sludge unit depends on
the site where the unit is to be located. The acceptability
of both active sewage sludge unit and surface disposal
site depend on the characteristics of the sewage sludge
to be disposed both from an operational and a regular-
tory  perspective.  For example, the solids  content of
sewage sludge impacts its suitability for placement in
different active sewage sludge  units  whereas regular-
tory  pollutant limits for sludge  are based on how far
the boundary of each active sewage sludge unit is from
the property line of the surface disposal site. For this
reason, sludge characteristics should be thoroughly in-

       Active Sewage
       Sludge Unit
       Boundary
                                                   Surface Disposal Site Property Line

Figure 2-1. Relationship between active sewage sludge unit and surface disposal site.

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                        Dedicated disposal site
        Surface impoundment
                   Waste pile                    Monofill


Figure 2-2.  Relationship between active sewage sludge unit and surface disposal site.
                 Dedicated beneficial
                     use site
vestigated first (see Chapter 3), followed by concurrent
investigations of sites  (see Chapter 4) and types of
active sewage sludge units.

It is important to note that there may be no one best
active sewage sludge unit for a given sludge or site. The
information given in this manual is intended  to provide
guidance as a starting point in selecting the type of unit
or unit(s) that may be most appropriate for a particular
situation.

The design criteria given in this chapter are based on
experiences at numerous surface disposal sites that span
a broad range  of  sludge and  site conditions. These
criteria should be valid  for most active sewage sludge
units; however, variations may be appropriate in  some
cases. For example, the range of sludge solids contents
recommended for each active sewage sludge unit might
vary somewhat depending on the sludge source, treat-
ment, and characteristics. Field tests should be performed
to ensure that an active sewage sludge unit based on
the criteria in this chapter will function properly for a given
sludge and site  (see Chapter 6). More detailed design
and operation information for the various types of active
sewage sludge units is provided in Chapters  7 and 8.


2.2  Overview of Sewage Sludge
      Disposal  Sites

From a regulatory standpoint, sewage sludge disposal
sites can be divided into two major categories:

• Disposal of sludge in an active sewage sludge unit
  on a surface disposal site. This is regulated under
  Part 503.

• Codisposal  of sewage sludge with household waste
  at a MSW landfill. This is regulated under  Part 258.
The active sewage sludge units regulated by Part 503
can be further divided into five major categories based
on design criteria:

•  Monofills—areas  where only, dewatered sewage
   sludge is disposed and covered with a soil cover that
   is thicker than the depth of the plow zone. Sludge
   may be deposited below the ground surface in exca-
   vated trenches, or on the ground surface in mounds,
   layers, or diked containments.

•  Waste piles—mounds of dewatered sludge placed on
   the soil surface, without a cover, for final disposal.1

•  Surface  impoundments and lagoons—units  where
   sludge is placed in an excavated or constructed area,
   without daily cover, for final disposal. The solids con-
   tent of sewage sludge in surface  impoundments is
   generally 2 percent to 5 percent. Below-ground (i.e.,
   excavated) surface impoundments are commonly re-
   ferred  to as lagoons. This document covers lagoons
   where sludge  is placed for final disposal.2

•  Dedicated surface disposal sites—sites where sew-
   age sludge is placed on the land by injecting it below
   the land  surface or incorporating it into the soil after
   being sprayed  or spread on the land surface. Dedi-
   cated disposal sites often are located at the treatment
 Under Part 503, any site where sludge remains on the ground for more
than 2 years is considered to be a surface disposal site regulated under
Part 503 unless the person who prepares the sewage sludge (i.e., gener-
ator of sewage sludge or a person who derives a material from sewage
sludge) demonstrates that the land on which the sewage sludge remains
is not an active sewage sludge unit.

 The term "lagoon" also refers to below-ground areas where sewage
sludge is placed for treatment prior to final disposal elsewhere. Lagoons
where sewage sludge is treated are not regulated under Part 503 and
are not covered in this document. If sewage sludge remains in a lagoon
for longer than 2 years it is regarded as surface disposal, unless the
person who prepares the sludge specifically demonstrates that treatment
Is occuring in the lagoon.
                                                    10

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  works site and receive repeated applications of sew-
  age sludge for the sole purpose of final disposal.

• Dedicated beneficial use sites—sites where sewage
  sludge is placed on the land by injecting it below the
  land surface or incorporating it into the soil after being
  sprayed or spread on the land surface. Such sites
  might or might  not  receive repeated applications of
  sewage sludge. In contrast  to dedicated disposal
  sites,  crops are grown on dedicated beneficial use
  sites.  For such  sites, the permitting  authority will is-
  sue a permit that specifies appropriate management
  practices that ensure the protection of public  health
  and the environment if crops are grown or animals
  are grazed on the site. Dedicated beneficial use sites
  are considered from a  regulatory standpoint to be
  surface disposal sites because sludge  is placed on
  sites at higher rates than  are permissible for land
  application sites regulated under Subpart B  (Land
  Application) of Part 503.

According to a 1988 National Sewage Sludge Survey
conducted by the U.S. Environmental Protection Agency
(EPA)(U.S. EPA, 1988), just over 10 percent of sewage
sludge used or disposed in 1988 was placed on a sur-
face disposal site. Of that 10 percent, 50 percent was
placed in dedicated disposal sites, just over 25 percent
was placed in monofills, and just under 25 percent was
disposed using  some other type  of  active sewage
sludge unit (e.g., impoundment or pile).

Table 2-1 summarizes and compares the sludge and site
conditions required by the various types of active sew-
age sludge units, and Table 2-2 summarizes and com-
pares the design criteria for these units. Active sewage
sludge units are distinguishable based on engineering
design experience, not on  any regulatory requirements.
The following discussion  outlines the  differences be-
tween these units based solely on design criteria and
established engineering practices.

2.3  Monofills

Monofills are active sewage sludge units where sewage
sludge with a solids content of at least 15 percent (or
more depending on the type of monofill) is disposed and
covered periodically. If cover is applied to the sludge at
the end  of each operating day, the  Part 503 pathogen
and vector attraction reduction  requirements are met
 (see Section 3A2).  The application of cover distin-
guishes  monofills from piles and dedicated disposal
sites, where the sludge  is not covered (unless it is
 injected  below the surface of the site), and from surface
 impoundments, which often receive no cover until the
 site is closed. The disposal of relatively high  solids
 sludge  distinguishes  monofills  from surface impound-
 ments and  dedicated disposal  sites,  where sludge of
 much lower solids content is typically disposed.
In monofills, insufficient oxygen is available for aerobic
decomposition. Monofilled sludge is slowly degraded by
anaerobic  decomposition.  If monofills  are properly
planned and operated, a completed  monofill site  can
ultimately be used by the owner for recreational or other
purposes, such as open space.

Monofills may be divided into  two basic categories:
trenches (where the sludge is placed in excavated areas
below the ground surface) and area fill's (in which sludge
is placed on the ground surface). These are discussed
below. Table 2-1 shows relevant sludge and site condi-
tions for the various types of monofills and Table 2-2
summarizes design criteria for these monofills.


2.3.1   Trenches

Trenches are excavated areas  in which the sludge is
placed entirely below the original ground surface. Good
engineering practice dictates that ground  water  and
bedrock in the area of a trench must be deep enough to
allow excavation and still maintain sufficient buffer soils
between the bottom of sludge deposits and the top of
ground water or bedrock.

With trenches, soil is normally used only for cover and
not as a bulking agent. The sludge is usually dumped
directly into the trench from haul vehicles. Onsite equip-
ment is generally used only for trench excavation and
cover application; it Is not normally used to haul, push,
layer, mound, or otherwise contact the sludge.

Cover is usually applied over sludge the same day it is
received. Cover places a barrier between sludge and
vectors and allows  the environment to reduce patho-
gens in sludge. Also, cover reduces odors. Daily cover
satisfies both the pathogen and vector attraction reduc-
tion requirements of Part 503, Subpart D (see Section
3.4.2), so.unstabilized or low-stabilized sludges can be
placed in trenches where cover is applied daily. The soil
excavated during trench  construction usually provides
sufficient soil for cover applications, so soil importation
is seldom required.

There are two basic types of trenches: narrow trench
and wide trench. Narrow trenches are up to 10 ft (3.0 m)
wide; wide trenches are more than 10 ft (3.0 m) wide.
The depth and length of both narrow and wide trenches
vary depending  on  several factors. Trench depth is a
function of (1) depth to ground water and bedrock, (2)
sidewall stability,  and (3) equipment limitations. Trench
length is virtually unlimited,  but inevitably depends on
property boundaries and other site conditions. Also,
trench length may be limited by the need to discontinue
the trench for a short distance or place a dike within the
trench to contain a low-solids sludge and prevent it from
flowing throughout the  trench.
                                                    11

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 Table 2-1.  Comparison of Sludge and Site Conditions for Various Active Sewage Sludge Units3
Method
Sludge
Solids
Content
Sludge
Characteristics'1
Hydrogeology0
Ground Slope
MONOFILL
Narrow trench
Wide trench
Area fill mound
Area fill layer
Diked containment
15-28%
520%
520%
>20%
>20%
Unstabilized or
stabilized
Unstabilized or
stabilized
Unstabilized or
stabilized
Unstabilized or
stabilized
Unstabilized or
stabilized
Deep ground water and
bedrock
Deep ground water and
bedrock
Shallow ground water or
bedrock
Shallow ground water or
bedrock
Shallow ground water or
bedrock
<20%
<10%
Suitable for steep terrain as long as
level area is prepared for mounding
Suitable for medium slopes but level
ground preferred
Suitable for steep terrain as long as a
level area is prepared inside dikes
PILES
 Piles
                          >28%
          Stabilized
                                                       Shallow ground water or
                                                       bedrock
                                      SURFACE IMPOUNDMENTS AND LAGOONS
 Surface Impoundments
 and lagoons
          Stabilized
                            Shallow ground water or
                            bedrock
                                          DEDICATED SURFACE DISPOSAL
 Dedicated surface
 disposal sites and
 dedicated beneficial
 use sites
53%
Stabilized
                            Deep ground water or
                            bedrock
                            CODISPOSAL OF SLUDGE IN MUNICIPAL SOLID WASTE LANDFILL
Sludgafliousehold
waste mixture
Sludge/soli mixture
                          520%
                          520%d
          Unstabilized or
          stabilized

          Stabilized
                  Deep or shallow ground
                  water or bedrock

                  Deep or shallow ground
                  water or bedrock
                                                                               <30%
* Note: This comparison is based on design requirements and not on any regulatory requirements.
  To protect human health and the environment, Part 503 regulates three characteristics of sewage sludge:  the content of certain heavy metals,
  the level of pathogens, and the attractiveness of the sludge to vectors. Sewage sludge placed on an active sewage sludge unit must meet
  the Part 503 requirements. Stabilization of sludge will generally be necessary to meet the Part 503 pathogen and vector attraction reduction
  requirements of any site where sludge is not covered at the end of each operating day.
d Part 503 requires that sewage sludge placed on an active sewage sludge unit shall not contaminate an aquifer.
  Sludge disposed of In a municipal solid waste landfill must have a high enough solids content to pass the Paint Filter Liquids Test.
2.3.1.1   Narrow Trenches

In narrow trenches (up to 10 ft [3.0 m] wide), sludge is
usually placed on the land once and a layer of cover soil
is placed atop the  sludge. Narrow trenches are usually
excavated by equipment on solid ground adjacent to the
trench and the equipment does not enter the excavation.
Backhoes, excavators, and trenching machines are par-
ticularly useful in narrow trench operations. Excavated
material is usually immediately applied as cover over an
adjacent sludge-filled trench.  However, occasionally, it
is stockpiled  alongside the trench from which  it  was
excavated for subsequent application as cover over that
trench. In this case, the cover material also is applied by
equipment based on solid ground outside the trench.
                               The main advantage of a narrow trench is its ability to
                               handle sludge with a relatively low solids content. As
                               shown  in Table 2-2, a 2 to 3 ft (0.6 to 0.9 m) width is
                               required for sludge with a solids  content between 15
                               percent and 20 percent. Normally,  soil applied as cover
                               over sludge of such low solids would sink to the bottom
                               of the sludge.  However, because of the narrowness of
                               the trench,  the soil cover bridges  over the sludge, re-
                               ceiving support from solid ground  on either side of the
                               trench.  Cover is usually applied in  a 2 to 3 ft (0.6 to 0.9
                               m) thickness.

                               Trenches over 3 ft (0.9 m) wide are too wide to provide
                               a bridging effect for the soil cover. Therefore,  sludge
                               with a higher solids contents must be used to support
                               the cover. For 3 to 10 ft (6.9 to 3.0 m) wide trenches,
                               solids content should  be 20 percent to 28 percent. For
                                                      12

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Table 2-2. Design Criteria for Various Active Sewage Sludge Units
Cover
Thickness
Sludge Imported
Solids Trench Bulking Bulking Bulking Soil
Method Content Width Required Agent Ratio8 Interim Final Required



Sludge Disposal
Rate" (in actual
fill areas)



Equipment
MONOFILL
Narrow trench 15-20% 2-3 ft No — — — 2-3 ft No
20-28% 3-1 Oft No — 3-4 "


Wide trench 20to<28% 10ft No — — — 3-4 ft No
>28% 10 ft No — 4-5 ft


Area fill mound ฃ20% — Yes Soil 0.5-2 soil: 3 ft 3-5 ft Yes
1 sludge


Area fill layer >20% — Yes Soil 0.25-1 soil: 0.5-1 ft 2-4 ft Yes
1 sludge

Diked 20to<28% — No Soil 0.25-0.5 soil: 1-2 ft 3-4 ft Yes
containment >28% — No Soil 1 sludge 2-3 ft 4-5 ft
1,200-5,600
yd3/acre


3,200-14,500
yd3/acre


3,000-14,000
yd3/acre


2,000-9,000
yd3/acre

4,800-15,000
yd3/acre
Backhoe with
loader,
excavator,
trenching
machine
Track loader,
dragline,
scraper, track
dozer
Track loader,
backhoe with
loader, track
dozer8
Track dozer,
grader, track
.. . e
loader
Dragline, track
dozer, scraper
PILES
Piles >28% — No — — - — — No
8,000-32,000
yd3/acre
Spreader,
bulldozer6
SURFACE IMPOUNDMENTS AND LAGOONS
Surface >2% — No — — — — No
impoundments
and lagoons
4,800-15,000
yd3/acre

Dragline,
front-end
loader0

DEDICATED SURFACE DISPOSAL
Dedicated ฃ:3% — No — — _ — No
surface
disposal sites
and dedicated
beneficial use
sites
50-2,000
tons/acre



Tank truck,
subsurface
injector, rotary
sprayer,
bulldozer6


CODISPOSAL OF SLUDGE IN MUNICIPAL SOLID WASTE LANDFILL
Sludge/ >20%f — Yes House- 4-7 tons/ 0.5-1 ft 2 ft No
house hold hold refuse:1 wet
waste mixture waste ton sludge
Sludge/soil S20%f — Yes Soil 1 soil: 0.5-1 ft 2ft No
mixture for 1 slud9e
cover
a Volume basis unless otherwise noted.
b These rates are based on design experience and established engineering practices.
0 Land-based equipment. - ,,._,,_.
d Land-based equipment for <28% solids sludge; sludge-based equipment for >28% solids sludge.
9 Sludge-based equipment.
' Sludge disposed of in a municipal solid waste landfill must have a high enough solids content to pass
1 ft = 0.35 m
1 yd3 = 0.765 m3
1 acre = 0.405 ha
500-4,200
yd3/acre

1,600yd3/acre




Dragline, track
loader

Tractor with
disc, grader,
track loader




the Paint Filter Liquid Test.






13

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  such trenches, cover is usually applied in a 3 to 4 ft (0.9
  to 1.2 m) thickness and dropped from a minimum height
  to minimize the amount of soil that sinks into sludge
  deposits.

  Another advantage of narrow trenches over wide trenches
  is that narrow trenches can be installed  on sloped terrain.
  This is done by running the narrow trenches parallel to
  the contours of the slope to ensure  that the sludge will
  spread out evenly within the trenches.

  The main disadvantage of narrow trenches is that they
  are relatively land-intensive, with generally lower sludge
  disposal rates than for other monof ills. As shown in Table
  2-2, typical sludge disposal  rates for  narrow trenches
  range from 1,200 to 5,600 yd3/acre (2,300 to 10,600
  m3/ha). Another drawback is that liners are impractical
  for narrow trenches. Sewage sludge placed on an active
  sewage sludge unit that has no  liner must meet the
  pollutant limits for arsenic, chromium, and nickel estab-
  lished in Subpart C of Part 503 (see Section 3.4.2.1).

 2.3.1.2   Wide Trenches

 Wide trenches (i.e., trenches with widths greater than 10
 ft [3.0 m]) are usually excavated by equipment operating
 inside the trench, so track loaders, draglines, scrapers,
 and track dozers are particularly useful in wide trench
 operations. Excavated material is usually stockpiled on
 solid ground adjacent to the trench  from which it  was
 excavated for subsequent application as cover over that
 trench. Occasionally excavated material is immediately
 applied as cover over an adjacent sludge-filled trench.
 Relevant sludge and site conditions  as well as design
 criteria are presented in Tables 2-1 and 2-2.

 Cover material may be applied to wide trenches in three
 ways, depending on the sludge solids content:

 • 20 percent up to 28 percent solids—sludge with 20
   percent up to 28 percent solids cannot support equip-
   ment. Therefore, cover should be applied in a 3 to 4
   ft (0.9 to 1.2 m) thickness by equipment based on
   solid undisturbed ground adjacent to the trench. A
   wide trench  may be only slightly more than 10 ft (3.0
   m) wide if a front-end loader is used to apply cover,
   or up to 50 ft (15 m) wide  if a dragline is  used to
   apply cover.

• 28 percent to 32 percent solids—sludge  with 28 per-
   cent to 32 percent solids  can support equipment.
  Therefore, cover should be applied by equipment that
  proceeds out over the sludge pushing a 4 to 5 ft (1.2
  to 1.5 m) thick cover before it. Track dozers are  the
  most useful piece of equipment for this task.

•  Greater than 32 percent solids—sludges  with greater
  than 32 percent or  more solids will  not spread out
  evenly in a trench when dumped from  atop the trench
  sidewall. If wide trenches are used for such high solids
    sludge,  haul vehicles should enter the trench and
    dump the sludge directly onto the trench floor. Cover
    soil can be applied either by equipment based on solid
    ground  adjacent to  the  trench  (and having long
    reaches out over the sludge), or by bulldozers and
    other heavy equipment located within the trench itself.

 As with narrow trenches, wide trenches should be oriented
 parallel to one another  to  minimize area  between
 trenches. Distances between trenches should only be
 long enough to provide sidewall stability and adequate
 space for  soil stockpiles, operating  equipment, and
 haul vehicles.

 One advantage of wide trenches compared to narrow
 trenches is that they are less land-intensive. Typical
 sludge application rates range from 3,200 to 14,500 yd3/
 acre (6,000 to 27,400 m3/ha). Another advantage of wide
 trenches is that liners can be installed to contain sludge
 moisture and protect the ground water.

 Two disadvantages of wide trenches compared to nar-
 row trenches are the need for a higher (20 percent or
 more) solids sludge and the need for flatter terrain. For
 wide trench applications with sludge less than 32 per-
 cent solids, sludge is dumped  from above and spread
 out evenly within the trench. Accordingly, the trench floor
 should be nearly level; this can be more easily effected
 when the trench is located in low relief  areas.

 2.3.2  Area Fills

 In  area fills, sludge is  placed  on the ground  surface.
 Because excavation is  not required  and sludge is not
 placed below the surface, area fill applications are more
 useful in areas with shallow ground water or  bedrock
 than  are excavated trenches. The  solids content  of
 sludge received at area fills must be at least 20  percent.
 Because area fills lack the sidewall containment avail-
 able from trenches and because the sludge in most area
 fills must be able to support equipment atop the sludge,
 sludge stability and bearing capacity  must be relatively
 good. To achieve these qualities, soil is usually mixed
 with the sludge as a bulking agent. The  large quantities
 of soil required  generally must be imported from off site
 or hauled from other locations on site, because  excava-
 tion is not usually performed in the area of the fill itself,
 where shallow ground water or bedrock may prevail.

 Liners are often installed at area fills where ground water
 or bedrock are close to the ground surface. Because
 sludge is placed on the ground surface at area  fills,
 liners can be more readily installed than at trenches.
 With or without liners, surface runoff of moisture from
 the sludge and contaminated rain water  can  be ex-
 pected at area fills,  and appropriate drainage control
facilities should be considered.  Part 503 requires  that
the runoff collection system of an active sewage sludge
 unit must have the capacity to handle  runoff  from  a
                                                   14

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25-year, 24-hour storm event. See Sections 7.5.6 and
7.5.7 for regulatory and design information on liners and
leachate  collection and removal systems, and Section
7.8.2 for  regulatory and design  information  on run-
on/runoff control systems.
In area fills, the sludge/soil mixture is placed on the land
in several consecutive lifts. Cover is usually applied after
each lift of the sludge/soil mixture is placed on the land.
Further cover may be applied as necessary to provide
stability for  additional lifts. Where daily cover  is not
applied at the end of each operating day, only sludges
capable of meeting the Part 503 pathogen and  vector
attraction reduction requirements (see Section  3.4.2)
may be placed on the area fill.

There are three basic types of area fills: area fill mound,
area fill layer, and diked containment, these are de-
scribed below. Sludge and site requirements and design
criteria are summarized in Tables 2-1 and 2-2.

2.3.2.1   Area Fill Mound
In an area fill mound, the solids content of sludge re-
ceived at the site must be at least 20 percent. Sludge
may be  mixed with a soil bulking agent to produce a
mixture with greater bearing capacity. Appropriate bulk-
ing ratios vary between 0.5 and 2 parts soil for each part
of sludge. The exact ratio depends on the solids content
of the sludge and the  need for  mound stability and
bearing capacity  (as dictated  by the number of lifts and
equipment weight).
The sludge/soil mixing to enhance bearing capacity is
usually performed at one location of the site and  the
mixture hauled to the filling area. At the filling  area, the
sludge/soil  mixture  is stacked into  mounds approxi-
mately 6 ft (1.8 m) high. Cover material  is then applied
atop these  mounds at least  3 ft  (0.9 m) thick.  Cover
thickness may be increased to 5 ft (1.5  m) if additional
mounds are applied atop the  first  lift.
 Lightweight equipment with "swamp pad" or "low  ground
 pressure" (LGP)  tracks is generally  recommended for
area fill  mound operations, such as mixing, mounding,
 and  covering operations, where the equipment may
 pass atop the sludge. Heavier wheel equipment may be
 more appropriate for transporting bulking material to and
from soil stockpiles.
 An  advantage of area fill mounds is their efficient land
 utilization. Sludge disposal rates are relatively  high at
 3,000 to 14,000 yd3/acre (5,700 to 26,400 rrvVha). A
 disadvantage of area fill mounds is the constant need to
 push and stack slumping mounds, which may increase
 manpower and equipment requirements. Some slump-
 ing is inevitable,  particularly  in  high  rainfall   areas.
 Slumping can sometimes be minimized by  providing
 earthen containment of mounds. For example, mounds
 are usually constructed on level ground to prevent them
from flowing downhill. If a steeply sloped site is selected,
however, a level mounding area can be prepared within
the slope and a sidewall created to contain mounds on
one side.

2.3.2.2   Area Fill Layer

Area fill layers might receive sludge with as little as 20
percent solids.  The sludge is then mixed with a soil
bulking agent to produce a mixture with greater bearing
capacity. Typical bulking ratios range from 0.25 to 1 part
soil for each part sludge. As with  area fill mounds, the
ratio depends on the sludge solids  content and the need
for layer stability  and bearing capacity (as dictated by
the number of layers and the equipment weight).

Mixing, to enhance bearing capacity, may occur either
in the filling area  or at a separate sludge dumping and
mixing area of the site. The mixture is spread evenly on
the area fill in 0.5 to  3 ft (0.15 to 0.9 m) thick layers.
Layering usually continues for several applications. In-
termediate cover between consecutive layers  may be
applied in 0.5 to 1 ft (0.15 to 0.3  m) thick layers. Final
cover, if applied, should be 2 to 4  ft (0.6 to 1.2m) thick.

Lightweight equipment with swamp pad  or LGP tracks
is generally recommended for operations, such as mix-
ing, layering,  and  covering, where the  equipment
passes on top of the sludge. Heavier wheel equipment
may be appropriate  for hauling  soil. Layered  areas
should  be constructed on flat ground to  prevent the
sludge from flowing downhill. However, layering can be
performed on mildly sloping terrain if the sludge  solids
content is high  and/or sufficient bulking soil  is used.
An advantage  of area fill layers  is that completed fill
areas are relatively stable in regard to bearing capacity,
so less extensive maintenance, manpower, and equip-
ment are required to push and stack slumping mounds
as compared to area fill mounds. A disadvantage is poor
land utilization  with sludge disposal rates from 2,000 to
9,000 yd3/acre (3,780 to  17,000 m3/ha).

2.3.2.3   Diked Containment

 In a diked containment, sludge is  placed entirely above
the ground surface and completely surrounded by dikes,
 or a combination of dikes  and  natural slopes if the
 containment area is at  the toe  of a steep  hill. Haul
 vehicles dump  sludge directly into the containment area
 from the sides  of the dikes.  Intermediate cover may be
 applied at certain points during the filling, and final cover
 may be applied when filling is discontinued.

 Diked containments require sludge with at least 20 per-
 cent solids. For sludges with solids contents between 20
 percent and 28 percent, cover material should be applied
 by equipment based on solid ground atop the dikes. Due
 to its long reach, a  dragline is the best equipment for
 cover application in  this situation. Intermediate cover
                                                    15

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 should be 1 to 2 ft (0.3 to 0.6 m) thick, and final cover
 should be 3 to 4 ft (0.9 to 1.2 m) thick.

 For sludges with 28 percent or greater solids contents,
 cover material can be applied by equipment that pushes
 and spreads cover soil into place as it proceeds out over
 the sludge. A track dozer is the best equipment for cover
 application in this situation.  Intermediate cover should
 be 2 to 3 ft (0.6 to 0.9 m) thick and final cover should be
 4 to 5 ft (1.2 to 1.5m) thick.

 Soil is usually not added to  sludge as a bulking  agent
 except for occasional additions as may be necessary to
 make possible the operations described above.

 Diked containments are relatively large—typically 50 to
 100 ft (15 to 30 m) wide, 100 to 200 ft (30 to 60 ft) long,
 and 10 to 30 ft (3 to 9 m) deep, or larger. Thus, one
 advantage of diked containments is efficient land use,
 with sludge loading rates of 4,800 and 15,000 yd3/acre
 (9,100 to 28,400 m3/ha). A disadvantage of diked con-
 tainment is that the depth of the fill and the weight of
 intermediate and final  covers place a significant sur-
 charge on the sludge. As a result, much of the sludge
 moisture is squeezed into surrounding dikes and into the
 floor of the containment. For active sewage sludge units
 that do not have a liner and leachate collection system,
 the concentrations of arsenic, chromium, and  nickel in
 the sludge must meet the  limits for these pollutants in
 Part 503 (see Section 3.4.2.1).

 2.4   Piles

 Sludge piles are mounds of sludge typically constructed
 at or above the ground surface  without any auxiliary
 containment structures  (e.g., dikes). Sludge piles  differ
 from sludge area fills (Section 2.3.2) in that cover is not
 applied to sludge piles .and addition of bulking  agent is
 optional. As with area fills, excavation is not required for
 piles, so piles are appropriate in areas with  shallow
 ground water or bedrock. Operational practices and
 equipment for sludge piles are often similar to those for
 wide trenches (see Section 2.3.1.2). Sludge solids con-
 tent for piles must be  at least 28  percent to ensure
 sufficient sludge stability and bearing capacity. Ground
 slope must be less than 5 percent to ensure that the pile
 does  not flow downhill.  Sludge is typically applied at a
 rate of 8,000 to 32,000 yd3/acres  (15,200 to 60,000
 m3/ha) using a spreader and a trackhoe. Table 2-1
 shows relevant sludge and site conditions and Table 2-2
 summarizes design criteria for piles.

 Because the sludge is not covered daily, it must be
treated priorto disposal to meet the pathogen and vector
attraction reduction requirements under Subpart  D  of
 Part 503 (see Section 3.4.2). Sometimes, piles are used
for storage prior to final use or disposal. Under Part 503,
any operation where sludge remains on the ground for
more  than  2 years is  an active  sewage sludge unit
 unless the person  who  prepares  the  sludge  demon-
 strates that the land is not an active sewage sludge unit.


 2.5  Surface Impoundments and Lagoons

 Surface  impoundments  are  above-ground or below-
 ground  installations where liquid  sewage sludge  is
 placed for final disposal.  The sludge usually has a low
 solids content (2 percent to 5 percent solids) and does
 not receive daily cover. Below-ground surface impound-
 ments are often referred to as lagoons. At above-ground
 installations, dikes are used to contain the sludge, and
 haul vehicles dump sludge directly into the containment
 area from the sides  of the dikes.

 The liquid level in both lagoons and above-ground sur-
 face impoundments is maintained at a constant height
 by an outflow pipe. Liquid usually leaves the impound-
 ment by evaporation and  through the outflow pipe. The
 outflow is either shunted to the inflow of the waste-
 water treatment plant or treated  prior to discharge
 into the environment. Seepage through the base of
 the impoundment is controlled either  by a liner  and
 leachate system or, in some cases, by  natural  geo-
 logical conditions.

 The particulate matter settles over time, and a layer of
 sediment accumulates on the floor of the impoundment.
 Eventually, the sediment  layer reaches the top of the
 lagoon or impoundment and no further inflow is possible.
 The lagoon or impoundment may then be covered  and
 closed.3

 Because of the relatively low sludge solids content, any
 cover application or dredging should be performed by
 equipment based on  solid  ground (i.e., atop the dikes for
 above-ground  installations).  Due to its  long reach,  a
 drag line is the best equipment in this situation.

 Disposal rates for lagoons or surface impoundments are
 similar to  those for diked containments and may range
 from 4,800 to 15,000 yd3/acre (9,100 to 28,400 m3/ha).
 Thus, one advantage  of lagoons or impoundments is
 relatively efficient land use in comparison to trenches or
 area fills. Table 2-1  shows  relevant sludge and  site
 conditions and Table 2-2 summarizes design criteria for
 lagoons or impoundments.
 Alternatively, the sludge may be dredged and used or disposed
through a different practice. If all of the sludge is dredged, the lagoon
or impoundment is not regarded as a surface disposal site under the
Part 503 regulation.  If any of the sludge remains in the lagoon or
impoundment longer than 2 years, the lagoon or impoundment is
regarded  as a surface disposal  site covered under the Part 503
regulations, unless the person who prepares the sewage sludge dem-
onstrates  that the surface impoundment or lagoon is not an active
sewage sludge unit (see Section 1.1 for more information on differen-
tiation between sludge disposal, storage, and treatment). Disposal of
dredged sludge from a lagoon or surface impoundment must meet
the Part 503 requirements if the dredged sludge is used or disposed
through one of the Part 503 practices.
                                                   16

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Because the sludge in a lagoon or surface impoundment
is not covered daily, it must be treated prior to disposal
to  meet the pathogen and vector attraction  reduction
requirements under Subpart D of Part 503 (see Section
3.4.2).

2.6   Dedicated Surface Disposal Sites

Dedicated surface disposal (DSD) sites are sites where
sewage sludge is placed on the land by injecting it below
the land surface  or  incorporating  it into the soil after
being sprayed or  spread on the land surface. Because
sludge is placed on surface disposal sites at higher rates
than are allowed when sludge is used as a soil amend-
ment, dedicated sites do not qualify as land application
sites under Subpart B of the Part 503 regulations. DSD
sites typically receive liquid sludges. Disposal of dewa-
tered or dried sludges is possible, but not common,
because other types of surface disposal sites are more
cost-effective for  these sludges. Many existing waste-
water treatment plants  practice some form of DSD be-
cause it is suitable for  liquid  sludges,  has minimal
transportation costs (if adequate acreage is available on
or adjacent to the treatment plant  site), and has rela-
tively low capital and operating costs.

Different methods of sludge  placement may be used,
depending on sludge solids content, ground slope, and
soil condition. These include:

•  Spraying using fixed or portable  irrigation systems.

•  Ridge and furrow methods similar to those  used in
   agricultural systems.

•  Direct surface spreading by tank trucks, tractors, and
   farm tank wagons. Sludge is spread from a manifold
   on the rear of  the truck or wagon as the vehicle is
   driven across the  DSD  site.

•  Subsurface injection, which involves cutting a furrow,
   delivering  sludge  into  the furrow, and covering  the
   sludge and furrow, all in one operation. Sludge may
   also be injected beneath the soil surface  or incorpo-
   rated using a disk.

 DSD sites are often  located on site at treatment works,
and sewage sludge is placed on these sites many times
each year for several years, for the sole purpose of final
disposal. Dedicated sites range in size from less than
 10 acres (4 hectares) to greater than 10,000  acres
 (4,000 hectares). Table 2-1 shows relevant  sludge and
 site conditions and Table 2-2 summarizes design criteria
for dedicated surface disposal.

 Because no cover is applied to sewage sludge at DSD
 sites, sludge must be stabilized prior to disposal to meet
 pathogen and vector attraction reduction requirements
 and to minimize odor.
Sludge disposal rates are determined by the sod'ds con-
tent of the sludge and climate, soil characteristics, and
other factors that affect the speed with which the soil
dries between sludge applications. Disposal rates range
from 50 to 2,000 tons/acre/yr. The disposal rate for a
particular site should not exceed the net soil evaporation
rate  (i.e., evaporation minus precipitation) so that the
soil can dry sufficiently between sludge disposal activi-
ties to allow the passage of sludge distribution vehicles.
If managed properly, water will be eliminated from the
soil by evaporation; however, runoff and leachate con-
trols are usually still necessary for those periods when
net soil evaporation rates are less than expected or
where more sludge than optimal is applied. Disposal
also should be managed to maintain aerobic conditions
so that the soil does not generate odors. Maintenance
of aerobic conditions depends  on the rate of sludge
application, the sludge: soil ratio, temperature, and fre-
quency of  soil  turning or disking. Meeting  the vector
attraction  reduction requirements of Part 503  will de-
crease odors at all surface disposal sites.

Dedicated surface disposal of sewage sludge often re-
quires storage capacity (such as facultative storage la-
goons)  (1)  to  provide  a  buffer between continuous
sludge production and intermittent DSD operations, and
(2) to store sludge during seasons when climatic factors
such as high rainfall or ground-freezing temperatures
require a suspension in sludge disposal.
The amount of land required for DSD depends on the
quantity of sludge generated and on  the acceptable
loading rate. Sufficient land must be available to ensure
the integrity of the system. A DSD site may have several
active sewage  sludge units.  Individual units should be
10 to 100 acres (4 to 40 ha) in area (50 acres [20 ha] is
typical). DSD active sewage  sludge units should have
fairly uniform elevations, although they may be regraded
depending on the requirements of the chosen method
for disposal.
Ground-water and surface water contamination can be
prevented by choosing a DSD site underlain with imper-
vious soil, hardpan, or rock to prevent vertical movement
of ground  water and  constructing dikes  and  cutoff
trenches to contain horizontal movement. Surface runoff
can be controlled by grading the site so that all surface
runoff drains to one point near the edge or corner of a
field and by disking in the sludge soon after spreading.
Each site  should be surrounded by  a berm  to keep
uncontaminated surface runoff out and to contain con-
taminated DSD runoff.

Dewatered sludge can be spread similarly to solid or
semi-solid fertilizers,  lime, or animal manure on DSD
sites. For example, sludge can be spread with bull-
dozers, loaders, graders,  or box spreaders, and then
plowed or disked in. Dewatered sludge may be applied
at higher rates than liquid sludge.
                                                    17

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 2.7   Dedicated Beneficial Use Sites

 Some DSD sites are  used to  grow feed and/or fiber
 crops or vegetative cover. These are known as dedi-
 cated beneficial use sites. For such sites, the permitting
 authority will issue a permit that specifies appropriate
 management  practices that  ensure the  protection  of
 public health and the environment if crops are grown on
 the site.

 A POTW or other DSD site owner might choose  to
 establish a beneficial  DSD site if soil erosion  or soil
 acidity are a  problem at the site or if the POTW is
 committed to a beneficial use policy. The  vegetation or
 crop  grown (e.g., a grassy cover crop or animal feed)
 can help control soil erosion and acidity and the sewage
 sludge can serve as a fertilizer  and  soil conditioner for
 the crop. The primary purpose of a DSD site, however,
 remains final disposal of sewage sludge; any growth of
 crops is secondary.

 Because vegetation/crops are grown on beneficial DSD
 sites, disposal rates of sludge are usually lower (e.g., 31
 to 83 mt/ha/yr4) (U.S. EPA, 1984) at these sites than on
 DSD sites  where no crops are grown. This is because
 the high sludge disposal rates generally  used at non-
 crop  producing DSD sites might result in accumulation
 of  metals  and other sludge constituents that might
 render the  soil unsuitable for crop production and may
 result in phytotoxicity. Conversely, because the sludge
 disposal rates at beneficial DSD sites are by definition
 higher than the agronomic rate of the crop, disposal
 rates at these sites are generally higher (but in accord-
 ance with Part 503 Subpart C surface disposal require-
 ments) than application rates at land application sites
 (e.g., farms, for which sludge must be applied at agro-
 nomic rates for nitrogen and must meet the other require-
 ments of Subpart B of Part 503 for land application).

 Part 503 requires that an owner/operator of a beneficial
 DSD  site must be able to demonstrate to the permitting
 authority that, by implementing certain management
 practices, public health and  the environment will  be
 protected if crops are grown or animals are grazed on
 these sites. Section 9.3.4.3 outlines additional informa-
 tion on growing crops on beneficial DSD sites.

 2.8  Codisposal at a Municipal Solid
      Waste Landfill

 Sludge can be codisposed with household waste (solid
 waste) at an MSW landfill. There are two basic types of
 codisposal methods: sludge/solid waste mixture and sludge/
 soil mixture. These two options are described below.
 Relevant sludge and site conditions as well as design
 criteria are presented Tables 2-1 and 2-2.
4 Some DSD sites apply sludge at much higher rates (2,000 tons
/acre/yr) and continue to grow crops).
 2.8.1  Sludge/Solid Waste Mixture

 In  a  sludge/solid waste mixture  operation,  sludge  is
 deposited atop solid waste at the working face of the
 landfill and  mixed as thoroughly  as  possible with the
 solid waste. The mixture is then spread, compacted, and
 covered in the usual manner used at  MSW landfills.

 Sewage sludge placed on a MSW landfill must pass
 the "paint filter test" under the Part 258 regulations (see
 Section 3.4.3), therefore the minimum  sludge solids con-
 tent for this option is approximately 20 percent. The sludge
 is  usually  spread  by conventional  landfill  operating
 equipment, such as bulldozers and landfill compactors.
 To  provide  adequate  workability of the sludge/solid
 waste mixture, the bulking ratio for a  20 percent solids
 sludge should be at least 4 tons of solid waste to 1 wet
 ton of sludge (4 Mg of solid waste to 1 wet Mg of sludge).

 Sludge application rates for sludge/solid waste mixtures
 compare favorably with rates for other types  of sludge
 disposal methods (e.g. rnonofills regulated under Part
 503), despite the fact that sludge is not the only waste
 being disposed on  the land.  Disposal  rates  generally
 range from 500 to 4,200 yd3 of sludge per acre (900 to
 7,900 m3 of sludge per ha).
2.8.2   Sludge/Soil Mixture

In a sludge/soil mixture operation, sludge is mixed with
soil and applied  as intermediate or final  cover over
completed areas of the MSW landfill. This is not strictly
a sludge landfilling method from an engineering stand-
point, because the sludge is not buried, but it is a viable
and proven option for codisposal of sludge at MSW
landfills.

One advantage  of this  approach over the sludge/
solid waste mixture option  described above is that it
removes sludge from the working face of the landfill
where  it may cause  operational problems  including
equipment  slipping or becoming  stuck in sludge,  or
sludge being tracked around the site by equipment and
haul vehicles. Other advantages are that the sludge/soil
cover promotes vegetation  over completed fill areas,
reduces the need for fertilizer, and minimizes siltation
and erosion.

One disadvantage of the  sludge/soil  mixture approach
compared to the sludge/solid waste mixture approach is
that it generally requires  more manpower and equip-
ment. Another disadvantage is that odors may be more
severe than for sludge/solid waste mixtures because the
sludge is not completely buried. For this reason, only
well-stabilized  sludges are  recommended  for  use  in
sludge/soil mixture operations.
                                                  18

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2.9   References
1. U.S. EPA. 1994. A plain English guide to the EPA 503 biosolids
   rule. EPA/832/R-93/003.
2.  U.S. EPA. 1988. National sewage sludge survey. Computerized
   database resident at National Computer Center, U.S. Environ-
   mental Protection Agency, Research Triangle Park, NC.
3.  U.S.  EPA.  1984. Use  and disposal of municipal wastewater
   sludge. EPA/625/10-84/003. Cincinnati, OH.
                                                            19

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                                             Chapter 3
           Characteristics of Sludge, Septage, and Other Wastewater Solids
3.1   Introduction

All types of wastewater treatment produce solids that must
be used or disposed. The characteristics of these solids
affect their suitability for surface disposal, either because
of regulatory restrictions or potential operational problems.
Therefore, when evaluating surface disposal alternatives,
a wastewater treatment plant should first determine the
amount and characteristics of its wastewater solids, and
the degree of variation in these characteristics.

This chapter reviews the characteristics of the various
solids generated,  and  explains  how these  charac-
teristics  impact the choice of an active sewage sludge
unit. Sections 3.3 and 3.4 discuss the characteristics of
sewage sludge affecting  disposal from a regulatory and
operational perspective, respectively.  This chapter di-
vides wastewater solids into three categories for discus-
sion purposes: sludge, septage, and other (screenings,
scum, and grit). EPA (1979) provides more information
on wastewater solids.

3.2   Types of Wastewater  Solids

3.2.1  Sludge

Sludge is a by-product of treatment of domestic sewage
(see Figure 1-1 in Chapter 1). Prior to dewatering, sew-
age sludge usually contains 93 percent to 99.5 percent
water as well as solids and dissolved substances that were
present in the domestic sewage and that were added or
cultured by wastewater treatment processes (U.S. EPA,
1984). Figure 1-2 in Chapter 1 provides the 40 CFR Part
503 regulatory definition of sewage sludge.
Usually sludge is treated prior to use or disposal. Table 3-1
lists various types of treatment processes and discusses
the effects of these processes on the disposal of sewage
sludge. EPA (1979) provides more information on sludge
treatment technologies. Sludge can be divided into three
basic types:  primary, secondary, and chemical.

3.2.1.1   Primary Sludge

Primary sludge is sludge generated by primary waste-
water treatment, which removes the solids that settle out
readily. Primary sludge typically contains 2 percent to 8
percent solids depending on the operating efficiency of
the clarifier and the amount of ground garbage in the
wastewater (U.S. EPA, 1978a). Usually, the water con-
tent can be easily reduced by thickening or dewatering.
Primary sludge has a larger particle size than secondary
sludge and is frequently mixed with secondary sludge
prior to treatment.

3.2.1.2   Secondary Sludge

Secondary sludge (also called biological sludge) is gen-
erated by secondary biological treatment  processes,
including activated sludge systems and attached growth
systems such as trickling filters. The quantities and char-
acteristics of secondary sludges vary with the metabolic
and growth rates of the various microorganisms present
in the sludge (U.S. EPA, 1979). Secondary sludge has
a low solids content (0.5 percent to 2  percent) and is
more difficult to thicken and dewaterthan primary sludge
and most chemical sludges.

3.2.1.3   Chemical Sludge

Chemical sludge is produced by advanced wastewater
treatment processes, such as chemical precipitation and
filtration.  These processes add  aluminum, iron,  salts,
lime, and/or .organic polymers to enhance the removal
of colloidal material, suspended solids, and phosphorus
from wastewater.  Chemical addition increases sludge
mass (and  usually volume). The characteristics of
chemical sludge depend on the wastewater treatment
process that produced it. Generally, lime  or polymers
improve the thickening and dewatering characteristics
of a sludge, whereas iron or aluminum  salts usually
reduce its dewatering and thickening capacity by pro-
ducing a very hydrous sludge that binds water.

3.2.2  Domestic Septage

Domestic septage  is the partially digested mixture of
liquid and solid material in domestic sewage that  accu-
mulates in a septic tank, cesspool, portable toilet, Type III
marine sanitation device, or similar treatment works. Sep-
tage accumulates in the treatment system for several
months or years until it is pumped out. Domestic septage
is either discharged into municipal wastewater systems
                                                  21

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Tabla 3-1.  Effects of Sludge Treatment Processes on Sewage Sludge Surface Disposal (U.S. EPA, 1984a, 1978a)

Treatment Process and Definition                Effect on Sludge                               Effect on Surface Disposal
Thlckonlng: Low-force separation of water
and solids by gravity, flotation, or
centrifugation. (Sludge thickeners may also
be used as flow equalization tanks to
minimize the effect of sludge quantity
fluctuations on subsequent treatment
processes.)

Digestion (Anaerobic and Aerobic):
Biological stabilization of sludge through
conversion of some of the organic matter to
water, carbon dioxide, and methane.
(Digesters may also be used to store sludge
to provide greater flexibility for the treatment
operation and to homogenize sludge solids to
facilitate subsequent handling procedures.)

Alkali Stabilization: Stabilization of sludge
through the addition of alkali.
Conditioning: Alteration of sludge properties
to facilitate the separation of water from
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 sludge with water and resettling
(elutriation); or briefly raising sludge
temperature and pressure (heat treatment).
Thermal conditioning also causes disinfection.

Dawatorlng: Separation of water and solids
for the purpose of thickening. Dewatering
methods Include vacuum filters, centrifuges,
filter presses, belt presses, lagoons, and
sand drying beds.
Composting: Aerobic process involving the
biological stabilization of sludge in a windrow,
aerated static pile, or vessel.
Heat Drying: Application of heat to reduce
pathogens and eliminate most of the water
content.
Increase solids concentration of sludge by
removing water, thereby lowering sludge
volume. May provide a blending function in
combining and mixing primary and secondary
sludges.
Reduces the volatile and biodegradable
organic content and the mass of sludge by
converting it to soluble material and gas. May
reduce volume by concentrating solids into a
denser sludge. Reduces pathogen levels and
controls  putrescibility' and odor.
Raises sludge pH. Temporarily decreases
biological activity. Reduces pathogen levels
and controls putrescibility. Increases the dry
solids mass of the sludge. Because pH
effects are temporary, decomposition,
leachate generation, and release of gas,
odors, and heavy metals may occur over time.

Improves sludge dewatering characteristics.
Conditioning may increase the mass of dry
solids to be handled and disposed without
increasing the organic content of the sludge.
Conditioning may also improve sludge
compactability and stabilization. Generally,
polymer-treated sludges tend to be sticky,
slick, and less workable than other sludges.
Some conditioned sludges are corrosive.


Increases solids concentration of sludge by
removing much of the entrained water,
thereby lowering sludge volume. Dewatering
may increase sludge solids to 15% to 40%
for organic sludges and 45% or more for
some inorganic sludges. Some nitrogen and
other soluble materials  are removed with the
water. Improves ease of handling by
converting liquid sludge to damp cake.
Reduces fuel requirements for heat drying.

Lowers biological activity. Can reduce most
pathogens. Degrades sludge to a humus-like
material. Increases sludge mass due to
addition of bulking agent.
Disinfects sludge. Lowers potential for odors
and biological activity.
Lowers sludge transportation
costs. Subsequent dewatering
will be required if the sludge is
to be monofilled or codisposed
in an MSW landfill.
Reduces sludge quantity.
Typical stabilization method
prior to surface disposal.
High pH of alkali-stabilized
sludge tends to immobilize
heavy metals in sludge.
Polymer-treated sludges may
require special operational
considerations at the surface
disposal site.
Reduces land requirements and
bulking soil requirements.
Lowers sludge transportation
costs.
Most likely not appropriate for
surface disposal due to cost.
Generally used to create a
sludge suitable for land
application rather than surface
disposal.

Most likely will not be used
when sludge is surface disposed.
for cotreatment with domestic sewage, discharged into
sludge for cotreatment and  use or disposal  with the
sludge, or treated and used or disposed separately.

Septage may be classified  as domestic,  commercial,
industrial, or a mixture. Figure 1-2 in Chapter 1  provides
the 40 CFR Part 503 regulatory definition of domestic
septage. Domestic septage generally includes liquid and
solid material derived from the treatment of domestic
sewage (e.g., wastes derived from the toilet, bath and
                 shower, sink, garbage disposal, dishwasher, and wash-
                 ing machine). Thus, domestic septage might be septage
                 from establishments such as schools,  restaurants, and
                 motels, as long as this septage does not contain other
                 types of wastes than those listed above (e.g., grease from
                 grease traps in restaurants). Domestic septage is regu-
                 lated under Part 503. Commercial and industrial septage
                 and mixtures of these septages with domestic septage
                 are regulated under 40 CFR Part 257 if disposed on the
                 land (or Part 258 if placed in a MSW landfill).
                                                         '  22

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Table 3-2 shows some characteristics of domestic sep-
tage. Septage may foam and generally has a strong
odor (U.S. EPA, 1978b). Settling properties are highly
variable. Some septage solids settle readily to about 20
to 50 percent of their original volume, while others show
little settling (U.S. EPA, 1979). Significant amounts of
grit may be present, and  large concentrations of total
coliforms, fecal  conforms, and fecal streptococci have
been found in septage (U.S. EPA, 1978b).

3.2.3   Other Wastewater Solids

In addition to sludge, other solids are generated during
wastewater treatment that must be handled properly.
These include screenings, grit, and scum. Scum is con-
sidered  sewage sludge and is regulated as such under
40 CFR  Part 503. Grit and screenings are regulated under
40 CFR  Part 257 (or Part 258 if placed in a MSW landfill).

3.2.3.1  Screenings

Screenings are solids such as rags, sticks, and trash in
the raw wastewater that are removed on racks or bar
screens placed at the head of the treatment works.
Racks and coarse screens (with openings larger than
0.25 inches [6 mm]) prevent debris from interfering with
other equipment. Fine screens (with openings from 0.01
to 0.25  inches  [0.25 to 6 mm]) remove a significant
fraction  of the suspended solids and reduce the biologi-
cal  oxygen demand of the influent, thus reducing the
load on  subsequent treatment processes.

Table 3-2. Chemical and Physical Characteristics of '
         Domestic Septage (U.S. EPA, 1993)
                                  Concentration
Parameter                      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 (BODs)
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%
The  quantity of screening captured in a treatment
works varies depending on the size of the rack or screen
openings. They typically have a moisture content of 85
percent to 95 percent and  an organic  content of 50
percent to 80 percent (U.S. EPA, 1975b). Screenings
are odorous and tend to attract rodents and insects.
They may contain pathogens. Screenings may be dis-
posed of separately from sewage sludge in which case
they are regulated under Part 257, or mixed with sewage
sludge and disposed together in which  case they are
regulated under Part 503.

3.2.3.2   Grit

Grit is composed of heavy, coarse, inert solids such as
sand, silt, gravel,  ashes, corn grains,  seeds,  coffee
grounds, and bottle caps associated with raw wastewa-
ter. Grit is usually removed at the head of the treatment
works, either by velocity control in simple gravity settling
chambers or by buoyant induction in air flotation tanks.
Grit may also be removed from primary sludge when it
has been separated from the wastewater. The amount
of grit varies tremendously from one treatment works to
another,  and can fluctuate  widely within a treatment
works. Grit is often washed after collection to reduce the
concentration of organics, which may be as high as 50
percent of the total grit solids and are largely responsible
for the odors associated with grit. When grit is  mixed
with  sewage sludge, the surface disposal of the mixture
is regulated  under Part 503. If grit is disposed  of sepa-
rately, it is regulated under Part 257.

3.2.3.3   Scum

Scum consists of  floatable materials in wastewater
and  is considered  sewage sludge under definition of
sewage sludge outlined in the Part 503 regulation (see
Figure 1-3 in Chapter 1). Scum may be  collected from
many different treatment units, including preaeration tanks,
skimming tanks, sedimentation basins, chlorine contact
tanks, gravity thickeners, and digesters (U.S. EPA, 1979).
(The term "skimmings" may also be used to refer to scum
that  has been removed.) Scum may be subsequently
digested, dewatered,  and  used or disposed. Unsta-
bilized scum may be highly odorous. Treatment of scum
in digesters is common, particularly with  mixed units.

3.3   Characteristics of Sewage Sludge
      Affecting  Disposal From a
      Regulatory Perspective

Surface disposal of sewage sludge and  domestic sep-
tage is regulated under 40 CFR Part 503 and codisposal
of sewage sludge in an MSW landfill under 40 CFR Part
258. The Part 503 and 258 requirements that pertain to
characteristics of sewage sludge and domestic septage
are described below.
                                                  23

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3.3.1   Part 503

To protect human health and the environment, Part 503
regulates three characteristics of sewage sludge (exclud-
ing domestic septage): the concentration of certain heavy
metals, the level of pathogens, and, the attractiveness
of the sludge to disease vectors, such as rodents, birds,
and insects. For domestic septage, Part 503 only regu-
lates its attractiveness to disease vectors.

Heavy metals are regulated under Subpart C  of  Part
503. Pathogens and vector attraction reduction require-
ments are contained in Subpart D of Part 503. Subpart
C of  Part  503  indicates which pathogen  and vector
attraction reduction  requirements have to  be met for
surface disposal. These requirements are summarized
below. EPA (1992a) provides greater detail on each of
the Subpart D requirements and guidance on  how to
meet the requirements.

3.3.1.1   Heavy Metals

The risk assessment performed to develop the Part 503
regulation found that three heavy metals can pose po-
tential risks to human  health and the environment in
surface  disposed  sludges:  arsenic,  chromium,  and
nickel  (U.S. EPA, 1992a). Therefore, Subpart C of 503
sets pollutant limits  for these metals in sewage sludge
placed on an active sewage  sludge unit. (These are the
only pollutants regulated by Part 503 for sewage sludge
placed on  a surface disposal site.) These  limits apply
only to active sewage sludge units without liners and
leachate collection systems  (see Section 7.2.1 for the
definition of a liner  and a leachate collection system).
Because  liners  prevent pollutants from migrating to
ground water,  sludge  placed  on  an active sewage
sludge unit with a  liner does  not have to  meet  the
pollutant limits. There are no  pollutant limits for domestic
septage placed  on a surface disposal site.

When sludge is placed on  an active sewage sludge
unit that does not have a liner  and leachate collection
system, representative samples of sludge must be peri-
odically collected (see Table 3-3 for frequency of moni-
toring) and analyzed for arsenic, chromium, and nickel
using the methods listed in the regulation (see Table  3-4).

There are  two  options for  meeting  the heavy metal
requirements. The first option is to ensure that the levels
of arsenic, chromium, and nickel are below the pollutant
limits listed in Table 3-5, which are based on how far the
boundary  of  each  active sewage sludge  unit  (e.g.,
trench) is from the property  line of the surface disposal
site. There may be more than one active sewage sludge
unit at a surface disposal site. Pollutant limits must be
determined for each unit separately based on the short-
est distance between each particular unit's boundaries
and the property line. Thus, there can be different  pol-
lutant limits for active sewage sludge units at the same
Table 3-3.  Frequency of Monitoring for Surface Disposal
          Under Part 503
Amount of Sewage Sludge
Placed on an Active Sewage
Sludge Unit (metric tons dry
solids per 365-day period)
           Frequency
Greater than zero but less than
290a

Equal to or greater than 290
but less than 1,500a

Equal to or greater than 1,500
but less than 15,000a

Equal to or greater than 15,000a
           Once per year
           Once per quarter (four times
           per year)

           Once per 60 days (six times
           per year)

           Once per month (12 times
           per year)
  a290 metric tons = 319 tons (approximately 0.9 tons/day for a
                 year)
 1,500 metric tons = 1,650 tons (approximately 4.5 tons/day for a
                 year)
15,000 metric tons = 16,500 tons (approximately 4.5 tons/day for
                 a year)
Table 3-4.  Methods Required by Part 503 for the Analysis of
          Metals in Sewage Sludge Placed on a Surface
          Disposal Site
Pollutants
Sample Preparation and Analytical
Methodologies SW-8463
Arsenic

Chromium

Nickel
EPA Methods 3050/3051 + 7061

EPA Methods 3050/3051 + 6010/7191/7190

EPA Methods 3050/3051 + 6010/5720
*Test Methods for Evaluating Solid Waste, Physical/Chemical Meth-
ods, EPA Publication SW-846, Second Edition (1982) with Updates I
(April 1984) and II (April 1985) and the Third Edition (November 1986)
with Revision I  (December 1987) and Update I  (July 1992).  The
Second Edition  and Updates I and II (PB-87-120-291) are available
from  the National Technical Information Service, 5285 Port Royal
Road, Springfield, VA 22161. The Third Edition and Revision I and
Update I (Document number 955-001-00000-1) are available from the
Superintendent of Documents, Government Printing Office, 941 North
Capitol Street, NE., Washington, DC 20002. Future updates will be
noticed in the Federal Register.
surface disposal site. Most likely, the most stringent of
the pollutant limits will be met at all of the active sewage
sludge units on the site.

The second option for meeting pollutant limits is to meet
"site-specific" limits approved by the permitting authority.
To invoke this option, the owner or operator of a surface
disposal site must request site-specific limits when ap-
plying for a permit. The permitting authority will then
evaluate the site conditions, determine  whether site-
specific limits are appropriate,  and, if  so, establish
those limits.

The need for site-specific limits  may be  justified if the
site conditions vary significantly from those assumed in
the risk assessment that EPA used to derive the regula-
tory pollutant limits. In general,  if the depth of ground
                                                     24

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Table 3-5. Part 503 Pollutant Limits for Sludge Placed on a Surface Disposal Site
                                                                        Pollutant Concentration
Location in the
Part 503 Rule
Table 2 of
Section 503.23




Table 1 of
Section 503.23
Distance From the Boundary of
Active Sludge Unit to Surface
Disposal Site Property Line (m)
0 to less than 25
25 to less than 50
50 to less than 75
75 to less than 100
100 to less than 125
125 to less than 150
Greater than 150
Arsenic
(mgfcg)
30
34
39
46
53
62
73
Chromium
(mg/kg)
200
220
260
300
360
450
600
Nickel
(mg/kg)
210
240
270
320
390
420
420
 ' Dry-weight basis (basically, 100% solids content).
water is considerable or a natural clay layer underlies
the site, site-specific limits might be established.

3.3.1.2   Pathogens
Pathogen reduction requirements for sewage sludge are
divided  into two categories: Class A and Class B. The
goal of the Class A requirements is to reduce the patho-
gens in sewage sludge  to  below  detectable levels
through treatment of the sludge. The goal of the Class
B requirements is to reduce pathogens (but not to below
detectable levels) and to prevent exposure to the sew-
age sludge to allow the environment to further reduce
pathogens to below detectable limits.
No pathogen requirements apply to domestic septage
placed  on a surface disposal site. Preparers of sewage
sludge, however,  have two  choices  in  meeting the
pathogen requirements:
• Meet one of the Class A alternatives.
• Meet one of the  Class B alternatives (excluding the
  Class B site restrictions, which do not apply to sur-
  face  disposal sites).
  or
• At the end of each operating day, the owner/operator
  could cover the  sewage  sludge wjth  soil or other
   material, in which case no pathogen  requirements
  apply.

 Class A Requirements
The Class A requirements are substantially more stringent
than the Class B requirements. Meeting them requires:
 • Monitoring sewage sludge to demonstrate that, at the
  time  of disposal, either the density of fecal coliform
   is less than 1,000 MPN (most probable number) per
   gram total solids  (dry weight basis) orthat Salmonella
   sp. bacteria density is below detectable levels.
• Either the use of particular operating conditions
  (e.g., achievement of particular time-temperature re-
  gimes, pH elevation, etc.) and/or treatment technolo-
  gies, or additional monitoring to demonstrate that both
  enteric viruses and viable helminth ova are  below
  detectable levels.

The Class A requirements are not discussed further in
this document, because it is likely that most preparers
of sewage sludge will choose the less stringent'Class B
or daily cover option to meet the Subpart  D pathogen
requirements. EPA (1992a) provides additional informa-
tion on the Class A requirements.

Class B Requirements

The Class B pathogen requirements can be met in three
different ways:

• Monitoring of Fecal Coliform. This alternative requires
  that the geometric mean fecal coliform in seven sam-
  ples of sludge  collected at the time of disposal (minus
  the time required to analyze the samples) be  less
  than 2 million  CPU (colony-forming unit)  or MPN per
  gram of  sewage sludge solids  (dry weight basis).
  Samples must be analyzed using Standard  Methods
  Part 9221 E or Part 9222 D (APHA, 1992).  Analysis
  of multiple samples during each monitoring episode
  is required because the analytical methods have poor
  precision  and  sewage sludge quality varies. Use of
  at least seven samples is expected  tb reduce the
  standard  error to a  reasonable  value  (U.S.  EPA,
  1992a).

• Use of a Process to Significantly Reduce Pathogens.
  Under this alternative, sewage sludge is considered
  to be Class B if it is treated in one of the "Processes
  to Significantly Reduce Pathogens"  (PSRPs) listed in
  Appendix B of Part 503 (see Table 3-6). This alter-
  native does not require microbiological monitoring.
                                                    25

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Table 3-6.  Processes to Significantly Reduce Pathogens
          (PSRPs) Listed in Appendix B of 40 CFR
          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 20ฐC
(68'F) and 60 days at 15ฐC (59'F).

2. Air Drying
Sewage sludge is dried on sand beds or on paved or unpaved
basins. Tha sewage sludge dries for a minimum of 3 months. During
2 of the 3 months, the ambient average daily temperature is above
O'C (32*F).

3. Anaerobic Digestion
Sewage sludge is treated in the absence of air for a specific
mean celt residence time (I.e., solids retention time) at a specific
temperature. Values for tie mean ceil residence time and
temperature shall be between 15 days at 35ฐC to 55ฐC (131ฐF)
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 (104ฐF) or higher for
5 days.  For 4 hours during the 5-day period, the temperature in the
compost pile exceeds 55ฐC (131ฐF).

5. Ume Stabilization
Sufficient lime is added to the sewage sludge to raise the pH of the
sewage sludge to 12 after 2 hours of contact
• Use of Processes Equivalent to PSRPs. Under this
  alternative,  sewage sludge treated by any  process
  determined to be equivalent to a PSRP is considered
  to meet the Class B requirements. The permitting
  authority is  responsible for deciding whether a proc-
  ess is equivalent to  a PSRP. This alternative does
  not require  microbiological monitoring.

Applying Soil Cover

The Subpart D pathogen requirements are satisfied if,
at the end of each operating day, the sewage sludge that
has been placed on an active sewage sludge unit is
covered with soil or other material. Daily cover isolates
the sewage sludge while environmental factors naturally
attenuate pathogens.  For daily  cover  requirements
based on best engineering judgement, see Table 2-2 in
Chapter 2.

3.3.1.3   Vector Attraction

Vectors are any living organisms  capable of transmit-
ting pathogens from one organism to another. They are
a principal route for transport of pathogens. Vectors for
transport of sewage sludge pathogens are generally
insects, rodents, and birds. Subpart  D of Part 503 requires
that the attractiveness of sewage  sludge to vectors be
reduced to decrease the disease risk from sludge. There
are 12 options for demonstrating reduced vector attrac-
tion under Part 503. These are summarized in Table 3-7.
Table 3-8 indicates the applicability of these options to
various types of sewage sludge and domestic septage.
EPA (1992a) provides more information on these options.

Options 1 through 8 apply to sewage sludge that has
been treated in some way to reduce vector attraction
(e.g., aerobic or anaerobic digestion, composting, alkali
addition, drying). These  options consist of operating
conditions or tests to demonstrate that vector attraction
has been reduced in the treated sludge. These options
do  not apply to domestic septage placed on a surface
disposal site.

Options 9 through 11 are barrier methods. These options
require the  use of soil as a physical  barrier to prevent
vectors from coming in contact with the sewage sludge,
Under option 11 (which applies only to surface disposal
sites), owners/operators of surface disposal sites can
satisfy the vector attraction  reduction requirement  by
covering the sewage sludge placed  on  a surface dis-
posal site with  soil or other material at the end of each
operating day.  (This option also automatically satisfies
the pathogen reduction requirement under Part 503.)
Options 9 through 11 apply to both sewage sludge and
domestic septage.

Option  12 is a requirement to demonstrate reduced
vector attraction through elevated pH. This option only
applies to domestic septage (not sewage sludge) placed
on a surface disposal site.

3.3.1.4  Frequency of Monitoring

The frequency  of monitoring  for the  pollutants  listed in
Table 3-5, the  pathogen density levels in the Class A
alternatives, the Class B fecal coliform levels, and vector
attraction reduction requirements 1 through 8 depends
on amount of sludge used or disposed.  Table 3-4 lists
this frequency. After the sewage sludge has been moni-
tored for 2 years at the frequency given in Table 3-3, the
permitting authority may reduce the frequency of moni-
toring for pollutant concentrations and for the enteric-vi-
ruses and viable helminth ova densities  in Class  A,
Alternative 3, down to no less than once a year.

When  option 12 (pH reduction) is used to meet the
vector attraction reduction requirements, each container
of domestic septage must be  monitored for compliance.

3.3.1.5   Organic Chemicals

Sludges can contain synthetic organic chemicals from
industrial wastes, household chemicals, and pesticides.
The risk assessment performed to develop the Part 503
regulation found that these chemicals do not generally
pose  a risk to  public health and the environment  in
surface-disposed sludges because they are generally
present at very low levels and most of these chemicals
degrade rapidly. Part 503 does not establish numerical
pollutant limits for any organic pollutants because EPA
                                                    26

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'• Table 3-7.  Summary of Requirements for Vector Attraction Reduction Under Part 503 (U.S. EPA, 1992a)

  Requirement                      What Is Required?                                     Most Appropriate for
 Option 1
 503.33(6X1)
 Option 2
 503.33(bM2)


 Options
 503.33(bX3)


 Option 4
 503.33(b)(4)

 Options
 S03.33(b)(5)


 Options
 503J3(b)(6)


 Option 7
 503.33(bK7)


 Options
 503.33(b)(8)
 Options
 S03.33(bM9)
 Option 10
 503.33(bX10)
 Option 11
 503.33(0X11)
  Option 12
  503.33(0X12)
At least 38% reduction in volatile solids during sewage
sludge treatment                        .
Less than 17% additional volatile solids loss during bench-
scale anaerobic batch digestion of the sewage sludge for
40 additional days at 30ฐC to 37ฐC (86ฐF to 99ฐF)

Less than 15% additional volatile solids reduction during
bench-scale aerobic batch digestion for 30 additional days
at 20ฐC (68-F)

SOUR at 20ฐC (68ฐF) is S1.5 mg oxygen/hr/g total
sewage sludge solids

Aerobic treatment of the sewage sludge for at least 14
days at over 40ฐC (104ฐF) with an average temperature
of over45''C(113<>F)

Addition of sufficient alkali to raise the pH to at least 12 at
25ฐC (77ฐF) and maintain a pH >12 for 2 hours and a pH
S11.5 for 22 more hours

Percent solids 275% prior to mixing with other materials
Percent solids >90% prior to mixing with other materials
Sewage sludge is injected into soil so that no significant
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.

Sewage sludge is incorporated into the soil within 6 hours
after application to land or placement on a surface
disposal site, except Class A sewage sludge which must
be applied to or placed on the land surface within 8 hours
after the pathogen reduction process.

Sewage sludge placed on a surface disposal site must be
covered with soil or other material at the end of each
operating day.

pH of domestic septage must be raised to 212 at 25ฐC
(77ฐF) by alkali addition and maintained at 212 for 30
minutes without adding more alkali.
Sewage sludge processed by:
• Anaerobic biological treatment
• Aerobic biological treatment
• Chemical oxidation

Only for anaerobicalty digested sewage, sludge that cannot
meet the requirements of Option 1


Only for aerobically digested sewage sludge with 2% or less
solids that cannot meet the requirements of Option 1—e.g.,  •
sewage sludges treated in extended aeration plants

Sewage sludges from aerobic processes (should not be
used for composted sludges)

Composted sewage sludge (Options 3 and 4 are likely to be
easier to meet for sludges 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)

Sewage sludge applied to the land or placed on a surface
disposal site. Domestic septage applied  to agricultural land.
a forest, or a reclamation site, or placed on a surface
disposal site


Sewage slgdge applied to the land or placed on a surface ,
disposal site. Domestic septage applied  to agricultural land,
forest, or a reclamation site, or placed on a surface disposal
site


Sewage sludge or domestic septage placed on a surface
disposal site


Domestic septage applied to agricultural land, a forest, or a
reclamation site or placed on a surface disposal site
  determined that  none of the  organics  considered for
  regulation were present  in sewage sludge that pose a
  public health or environmental risk. EPA used the follow-
  ing criteria to make this determination:

  • The pollutant is banned or has restricted use in the
    United States or is no longer manufactured or used
    in manufacturing a product 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 1988 National Sewage Sludge Survey;
    or
    The pollutant limit  identified in EPA's exposure as-
    sessment is not expected to be exceeded in sewage
    sludge that is used or disposed, based on data from
    the National  Sewage Sludge Survey.
                                              3.3.1.6   Nitrogen

                                              Nitrogen in sludge is a source of potential ground-water
                                              pollution. The potential for ground-water pollution is sig-
                                              nificantly affected by the quantity and type of nitrogen.
                                              Nitrogen may be present in sludge as organic nitrogen,
                                              ammonia, nitrate, and  nitrite. Generally, nitrate is the
                                              principal species of concern because  it is the  most
                                              soluble form of nitrogen, and therefore is relatively mo-
                                              bile in most soil types.  Aerobic conditions facilitate mi-
                                              crobial conversion of other nitrogen species to  nitrate,
                                              and thus, increase  the possibility  for nitrogen move-
                                              ment. Conversely, disposal methods providing anaero-
                                              bic  conditions  inhibit  nitrogen  movement  and allow
                                              microbial destruction of pathogens (U.S. EPA, 1975a).

                                              One of the management practices  required under Part
                                              503 states  that sewage  sludge  placed ,on an active
                                              sewage sludge unit must not contaminate  an aquifer.
                                                            27

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Table 3-8. Applicability of Options for Meeting the Vector
         Attraction Reduction Options Under Subpart D
                Sewage Sludge
             (Excluding Domestic
               Septage) Placed
             on an Active Sewage
                 Sludge Unit
 Domestic Septage
Placed on an Active
Sewage Sludge Unit
Options 1-8
Options 9-11
Optfon 12
Under this management practice nitrate-nitrogen levels
in ground water must not exceed the MCL of 10 mg/liter
or must  not increase the  existing concentration of ni-
trate-nitrogen if the existing concentration already ex-
ceeds the MCL.

3.3.2 Part 258

EPA's Solid Waste Disposal Facility Criteria contain pro-
visions that prohibit the receipt of hazardous waste at
municipal solid waste  landfills  (40 CFR 258.20). The
regulations also prohibit the receipt of bulk or noncpn-
tainerized liquid waste (40  CFR 258.28).  Part 503.4
establishes the same requirements for the codisposal of
sewage sludge at MSW landfills.

3.3.2.1   Exclusion  of Hazardous Waste From
         Municipal Solid Waste Landfills

Under 40 CFR Part 258.20, owners or operators of
municipal solid waste  landfills must implement a pro-
gram for detecting and preventing the disposal of regu-
lated hazardous waste and polychlorinated biphenyls
(PCBs).  EPA considers a waste to be  hazardous if it
exhibits the characteristics of ignitability, corrosivity,  re-
activity, or toxicity (i.e., it is a "characteristic" waste), or
if it is on a list of specific wastes determined by EPA to
be hazardous.

Sewage  sludge is not a listed hazardous waste. More-
over, available evidence suggests that sewage sludges
are unlikely to be a characteristic hazardous waste. The
non-hazardous nature  of sewage sludges  cannot nec-
essarily be assumed,  however, and as sludge gener-
ators, POTWs and other treatment works are required
under 40 CFR Part 262.11 to determine whether their
sewage sludge is a hazardous waste by virtue of its
characteristics (U.S.  EPA,  1990).

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 are  expected to
exhibit the toxicity characteristic (55 FR 11838). How-
ever, if factors are present indicating  a likely  toxicity
problem  (e.g., a  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 a hazardous waste, it is
advisable for the treatment works  to test  the sludge
destined for codisposal for toxicity (U.S. EPA, 1990).

The test for toxicity is the Toxicity Characteristic Leach-
ing Procedure (TCLP). This test simulates leaching in a
municipal landfill, measuring the potential of certain toxic
constituents to leach out and contaminate ground water
at levels of health or environmental concern. Table 3-9
lists  the  toxicity characteristic constituents and their
regulatory levels.

3.3.2.2   Liquids Restriction

One of the  key considerations for a sludge/municipal
solid waste codisposal operation is ensuring that the
sludge meets the liquids restriction of 40 CFR Part 258.
This restriction helps  reduce  the  amount of  landfill
leachate and the concentrations of contaminants in the
leachate. Sludge may not be disposed in a municipal
solid waste landfill  if it is determined to contain free
liquids as defined by Method 9095 - Paint Filter Liquids
Test, as described in 'Test Methods for Evaluating Solid
Wastes,  Physical/Chemical  Methods" (EPA Pub. No.
SW-846).  The paint filter liquids test is performed by
placing a 100-ml sample of waste in a conical, 400-mi-
cron paint filter. The waste is considered a liquid  waste
if any liquid from the waste  passes through the filter
within 5 minutes. The apparatus used to,perform the
paint filter test consists of a glass funnel, a ringstand to
hold the funnel, a graduated cylinder, and the paint filter
(Figure 3-1).
                                                           * Paint Filter
                                          Funnel -^
                                - Ring Stand
                                                        -Graduated Cylinder
                     Figure 3-1.  Paint filter test apparatus (U.S. EPA, 1993b).

                     The solids content required for a sludge to pass the paint
                     filter liquids test depends on the origin of the sludge.
                     One study found that primary sludges required an aver-
                     age of 15.6 percent solids to  pass the test,  mixed
                     sludges 13 percent, and biological sludge 5.5 percent.
                                                   28

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Table 3-9. Toxicity Characteristic Constituents and Regulatory Levels
EPAHWNo.'

D005
D0 18

D019
D021
D022
D007
D023
D024
D025
D026
D016
ryW7
D028

D030
D031
0032

D034

D013
D009

0035
0036
D037
D038
0010
D011
D039
0015
0040
D041
0042
0017
0043

Constituent (mg/L)
.
Barium
Benzofio 	 - 	 _..............ซ... 	 -ปซ ซ 	 — 	 • •ซซ•"

Carbon tetrachloride 	 .. — ..... 	 — .- 	 	

o~Cresol i 	 	 ^__ 	 . L __ 	 	
D-Or6soJ 	 | 	 ii..i_i_.iiii.n 	 TII-IIT--IT 	 	 	
2 4-D 	 	 	 	 	 	 	




Hoptachlor (and its hydroxide) 	 	 _.._..„..._... 	 	 	
HflXschtorobenzofTO . • • *ป 	 ........


Lead „ ... , 	 ...., ,..-,-' 	 ,!.,..„„.,,.„,,„,





PentactitofophefioJ .. 	 	 — 	 ซ.*.... i . — m —
Pvririina ...... 	 .......

Silver . . - 	 ..—
Tetrachloroettiylerwj . ... ........ 	 	 - ,.,...ป 	


2.4, 5-Trichkxophenol ._-_-....._. 	 ,,,,,„,,„„--,,,-,„, 	 	 	 	 —
2 4 5-Tp (SHvex) . ... 	 	 	
Vinyl chlorklfl

CAS No.'
7440-38-2
7440-39-3
71-43-2
7440-43-9
56-23-5
57-74-9
109-90-7
67-66-3
7440-47-3
95-48-7
108-39-4
106-44-5
94-75-7
106-46-7
107-06-2
75-35-4
121-14-2
72-20-8
76-44-8
1 18-74-1'
87-68-3
67-72-1
7439-92-1
58-89-9
7439-97-ซ
72-43-5
78-93-3
98-95-3
87-86-5
110-86-1
7782-49 2
7440-22-4
127-18-4
8001-35-2
79-01-6
95-95-4
88-06-2
93-72-1
75-01-4

Chronic toxicity reference
(eve) (mg/L)
O.D5
1.0
0.005
0.01
O.DOS
0.0003
1
0.06
0.05
2
2
2
2
0,1
0.075
0.005
0.007
0.0005
0.0002
000008
00002
0005
003
005
0004
0002
0.1
2
002
1 '
004
0.01
0.05
0,007
0.005
0.005
4
0.02
0.01
0.002

Regulatory
level  Hazardous waste number.
    1 Chemical abstracts service number.
   ซIf o-. rrh!"*U p^JofcoJcentraiion* cannot b^differentiated. thatotal cresd (0026) conosntraBon is usedLThs regulatory tevaJ tor total cresd <* 200 mg/L
 All wastewater sludges dewatered on conventional
 dewatering equipment were found to  attain a solids
 content comfortably above the solids content needed to
 pass the paint filter liquids test (U.S. EPA, 1992b).

 The study also found that a sludge that passes the test
 at the treatment works could fail after standing for sev-
 eral hours. For this reason, it is recommended that the
 test at the treatment works be conducted under more
 severe conditions than required by the paint filter liquids
 test. This can be accomplished by increasing the hydro-
 static head of .the filter. A simple way  to do this is to
 conduct the test using a larger volume of sludge (e.g.,
 using a larger funnel  and 800 ml of sludge instead of
 100 ml, thus increasing the hydrostatic head from about
 6.5 cm to 13 cm)  (U.S. EPA, 1992b).

 Mixing a dewatered sludge cake will also help ensure
 that it will pass the paint filter liquids test. When a sludge
 has been dewatered, it  is usually not uniform in solids
 content.  For example, in filtration, the cake next to the
 filter cloth has a higher solids content than the sludge at
 the outer edge of the cake. This lack of uniformity could
 result in  the sludge failing to pass the paint filter liquids
 test (U.S. EPA, 1992b).
If the sludge is determined through the paint filter liquids
test to be liquid waste, absorbent materials (such as soil)
may be  added  to  render a  "solid" material (i.e., a
waste/absorbent mixture that no loneier fails the paint
filter liquids test).

3.4  Characteristics of Sewage Sludge
      Affecting Disposal From a Technical
      Perspective
This section discusses the characteristics of sewage
sludge that influence the design of surface disposal sites
because of potential operational problems.  For exam-
ple, the  solids content of  sewage  sludge impacts its
suitability for disposal at different active sewage sludge
units  (e.g.,  monofills versus lagoonซ).  In addition to
solids content, this section reviews how sludge quantity,
organic content, and pH affect the suitability of sewage
sludge for disposal from a technical perspective.

3.4.1   Solids Content
The solids  content of sludge—usually expressed as
percent total solids (TS)—can affect jiludge transporta-
tion costs,  leachate formationi and the effectiveness of
                                                     29

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 surface disposal equipment.  The  solids  content of
 sludge depends on the type of sludge (i.e.,  primary,
 secondary, chemical)  and on whether and how it  has
 been further treated (see Table 3-1) prior to disposal.
 Treatment processes such as thickening, conditioning,
 dewatering, composting, and drying can lower sludge
 water content and thus raise the percent solids. The
 efficiency of these treatment processes, however,  can
 vary substantially from time to time, producing  sludges
 with substantially lower solids content than the  process
 was designed to produce. Therefore, it is critical that
 surface disposal sites be flexibly designed to accommo-
 date the range of variations in sludge solids content that
 may occur as a result of variations  in the efficiency of
 the wastewater and sludge treatment processes. With-
 out  this flexibility, severe operational problems could
 result at the disposal site.

 The sludge solids content that can be tolerated at any
 particular surface disposal site depends on a variety of
 operational and site-specific factors. Table 2-2 in Chap-
 ter 2 lists the ranges of acceptable  sludge solids con-
 centrations for the types of active sewage sludge units.
 For monofills and codisposal operations, sludge solids
 concentration  should be at least 20 percent.  Dedicated
 surface disposal sites and surface impoundments typi-
 cally handle sludge of much lower solids concentrations,
 while piles require sludge of higher solids concentration.
 Polymers are  sometimes added to sludge to create a
 higher solids content. The addition of polymers to con-
 dition sludges creates a more viscous, sticky, slippery
 material that can cause handling difficulties.

 3.4.2  Sludge Quantity

 The amount of sludge that must be used or disposed
 affects the economic and technical feasibility of the sur-
 face disposal options. Two ways to look at sludge quan-
 tity are the volume of the wet sludge, which  takes into
 account both the water content and the solids content,
 and the mass of the dry sludge solids. Sludge volume is
 expressed as gallons  (liters) or cubic meters.  Sludge
 mass is usually expressed in terms of weight, in  units of
 dry metric tonnes (tons). Because the water content of
 sludge can be high and quite variable, the mass of  dry
 sludge  solids  is often  used to compare sludges with
 different proportions of water (U.S. EPA, 1984).

 Key factors affecting sludge volume and mass are sources
 of the wastewater, wastewater treatment processes, and
sludge treatment processes. For example, industrial con-
tributions to the  influent wastewater can significantly in-
crease the sludge quantity generated from a given  amount
of wastewater. Also, higher degrees of wastewater treat-
 ment generally increase sludge volume. As documented
in Table  3-1, some sludge treatment processes reduce
sludge volume, some reduce sludge mass,  and some
 increase  sludge  mass while improving other sludge
 characteristics (U.S. EPA, 1984).

 The sludge quantity determines the surface disposal
 area requirements and the probable life of the disposal
 site. Data on minimum and maximum sludge quantities
 are Important for developing an understanding of the
 daily operating  requirements. Maximum daily sludge
 quantities will govern equipment and  storage facility
 sizing and daily operating schedules (U.S. EPA, 1979).

 3.4.3   Organic Content

 Sludge  organic content is an important determinant  of
 potential odor problems in surface disposal.  Sludge or-
 ganic content is most often expressed as the percent  of
 total solids (TS) that are volatile solids (VS). VS are organic
 compounds that are removed when the sludge is heated
 to 550ฐC (1,022ฐF) under oxidizing conditions (U.S. EPA,
 1984). Most unstabilized sludge contains 75 percent to 85
 percent VS on a dry weight basis. A number of treatment
 processes can be used to reduce sludge volatile solids
 content and thus the potential for odor. These include
 anaerobic digestion, aerobic digestion, and composting.
 Anaerobic digestion—the  most  common  method  of
 sludge  stabilization—generally  biodegrades  about 50
 percent of the volatile solids in a sludge.

 3.4.4   pH

The  pH of a  sludge affects its suitability  for surface
disposal. Low pH sludges (less than approximately pH
6.5)  promote leaching of most heavy metals. High pH
sludges (greater than pH 11) destroy many bacteria and,
 in  conjunction with soils  of  neutral or high pH,  can
temporarily inhibit movement of most heavy metals
through soils. Also, biological activity is reduced in high
pH sludges, leading to a reduction in the decomposition
of  organic material in the sludge which in turn reduces
its attraction to vectors.

3.5   References
 1. American Public Health Association (APHA). 1992. Standard
   methods for the examination of water and wastewater, 18th ed.
   Washington, DC.
 2. U.S.  EPA.  1993a.  Domestic septage  regulatory  guidance.
   EPA/832/B-92/005. Washington, DC.
 3. U.S. EPA. 1993b. Solid waste facility disposal criteria: Technical
   manual. EPA/530/R-93/017 (NTIS PB94-100-450) (November).
 4. U.S. EPA. 1992a. Control of pathogens and vector attraction  in
   sewage sludge. EPA/625/R-92/013. Cincinnati, OH.
 5. U.S. EPA. 1992b. The relationship between free liquids and solids
   content for sewage sludges. EPA/600/J-92/303  (NTIS PB92-
   227453).
 6. U.S.  EPA.  1984. Use and  disposal of municipal wastewater
   sludge. EPA/625/10-84/003, Cincinnati, OH.
 7. U.S. EPA. 1979. Process design manual for sludge treatment and
   disposal. EPA/625/1-79/011. Cincinnati, OH.
                                                    30

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8.  U.S. EPA. 1978a. Process design manual: Municipal sludge land-
   fills. EPA/625/1-78/010. Cincinnati, OH.
9.  U.S. EPA. 1978b. Treatment and disposal of septic tank sludges:
   A status report. Distributed at the Seminar on Small Wastewater
   Facilities. Cincinnati, OH.
10. U.S. EPA. 1975a. Trench incorporation of sewage sludge in mar-
    ginal agricultural land. EPA/600/2-75/034.

11. U.S.  EPA. 1975b. Sludge  processing, transportation, and dis-
    posal/ resource  recovery: A planning  perspective.  EPA/WA-
    75/RO24.
                                                             31

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                                                Chapter 4
                                             Site Selection
4.1   Purpose and Scope

This chapter presents the regulatory, technical, and
economic considerations relevant to selecting the loca-
tion of a surface disposal site, describes a process for
site selection, and  provides an example showing how
this process applies to selecting a surface disposal site.
A surface disposal  site is an area of land that contains
one or more active sewage sludge units. Figure 2-1 in
Chapter 2 illustrates the relationship between an active
sewage sludge unit and a surface disposal site.

In addition to regulatory, technical, and economic con-
siderations, site selection is also  influenced  by the
degree of public participation and acceptance.  Public
input should be received throughout the site selection
process. Approaches to ensuring effective public partici-
pation are addressed in Chapter 5.
When selecting and developing a  site, municipalities
should be aware of the lead time involved before the site
will be operational.  Site selection is an iterative process.
Often many candidate sites are reviewed  leading to
many feasible sites, from which a final site is selected.
Figure 4-1 illustrates the flow of the screening process
for site selection.  Site selection methodology  is  dis-
cussed in detail in  Section 4.4.

Permitting, evaluation, public review, purchase, and de-
velopment of a surface disposal site usually take 3 to 5
years or more.  Underestimation of this lead time may
lead to expensive storage or transportation of sludge.

4.2   Regulatory Requirements

4.2.1   Part 503

Surface disposal sites where sewage sludge is  placed
for final disposal in monofills, surface impoundments, or
piles and mounds,  dedicated surface disposal sites, and
dedicated beneficial use sites are all covered by the Part
503 Subpart C  regulation. Several of the  management
practices required under Subpart  C influence where
 surface disposal sites can be located.  Some of these
 requirements clearly prohibit sites with certain charac-
teristics from consideration; others, while not prohibitive,
 may result in increased costs or permitting requirements
for sites with certain characteristics, making these sites
less desirable than other options. Subpart C require-
ments influencing siting are summarized  in Table 4-1
and explained below.

4.2.1.1   Protection of Threatened  or Endangered
         Species

Under Part 503, sewage sludge cannot be placed on an
active sewage sludge unit if it is likely to adversely affect
a threatened or endangered species listed under Sec-
tion 4 of the Endangered  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 Washington,  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

Table  4-1.  Part 503 Subpart C  Management Practices
          Influencing Siting of an Active  Sewage Sludge Unit

• Sewage sludge shall not be placed on an active sewage sludge
  unit if it is likely to adversely affect a threatened or endangered
  species listed under section 4 of the Endangered Species Act or
  its designated critical habitat.
• An  active sewage sludge  unit shall not restrict the flow of a
  base flood.
• When a surface  disposal site is located in a seismic impact
  zone, an active sewage sludge unit shall be designed to
  withstand the maximum recorded horizontal ground level
  acceleration.
• An  active sewage sludge  unit shall be located 60 meters or
  more from a fault that has displacement in Holocene time,
  unless otherwise specified by the permitting authority.
• An  active sewage sludge  unit shall not be  located in  an
  unstable area.
• An  active sewage sludge unit shall not be  located in  a wetland,
  except as provided in a permit issued pursuant to section 402
  or 404 of the CWA.
 •  Sewage sludge  placed on an active sewage sludge unit shall
   not contaminate an  aquifer.
                                                     33

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                                   TRIGGERING
                                   MECHANISM
                                 DEVELOP
                                 M0DIFY SELECTION
                                 PROCESS
                                 AREAS  OF
                                 CONSIDERATION
                                                                          FEASIBLE.
                                                                           SITSS
                      SITE
                     SELECTED
                                         OPERAT/ONS
Figure 4-1. Flow of screening process for site selection (U.S. EPA, 1985).
Species Protection Program in Washington, DC, or FWS
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.
4.2.1.2   Restriction of Base Flood Flow

Part 503 requires that an active sewage sludge unit "not
restrict the flow of a base flood." A base flood is a flood
that has a 1 percent chance of occurring in any given
year (i.e., a flood that is  likely to occur once in  100
years). This management practice:

• Reduces the possibility  that a surface disposal  site
  might negatively affect the ability of an area to absorb
  the flow of a base flood.

• Prevents surface water contamination.

• Protects the public from the possibility of a base flood
  releasing sewage sludge to the environment.

The  flood  insurance rate maps (FIRMs)  and flood
boundary and floodway maps published by the Federal
                                                   34

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Emergency Management Agency's (FEMA's) Flood Map
Distribution Center in Baltimore, Maryland can be con-
sulted to determine whether a surface disposal site is in
a 100-year flood  plain. Guidance on using FIRMs is
provided in "How to Read a Flood Insurance Rate Map"
published by FEMA. FEMAalso publishes 'The National
Flood Insurance Program Community Status Book" that
lists communities that are in the Emergency or Regular
program including communities that may not be involved
in the National Flood Insurance Program but which have
FIRMs or Floodway maps published. States,  counties,
and towns usually also  have maps delineating  flood-
plains. Other agencies that maintain flood zone maps
are the U.S. Army Corps of Engineers (COE), the U.S.
Geological  Survey (USGS), the U.S. Soil Conservation
Service (SCS), the Bureau of Land Management (BLM),
the Tennessee  Valley Authority (TVA), and state and
local agencies.

Many of the river channels covered by these maps may
have  been modified for  hydropower or flood  control
purposes,  so the floodplain boundaries represented
may not be accurate or representative. Comparison of
the floodplain map series to recent air photographs may
be necessary to identify current river channel  modifica-
tions and land use in watersheds that could affect flood-
plain designations.

If floodplain maps are not available, and the potential
active sewage sludge unit is located  within a floodplain,
a field study may be required to delineate the 100-year
floodplain. Such a study would likely involve  reviewing
meteorological  records and physiographic information
including existing and planned watershed land use, to-
pography, soils and geologic mapping,  and  air photo
interpretation of geomorphologic features.

If the owner/operator of a surface disposal site deter-
mines that an active sewage sludge unit is within a 100-
year flood zone, the permitting authority will evaluate
whether the  active sewage sludge unit will restrict the
flow of a base flood. This assessment considers the flood
plain storage capacity and the floodwater velocities that
would exist with and without the presence of the active
sewage sludge unit. If the presence of the unit will raise
the base flood level 1 additional foot, the unit  is consid-
ered to restrict the flow of the base flood, potentially
causing more  flood damage than would  otherwise
have occurred.

If the  permitting  authority believes  an  active sewage
sludge unit will  restrict the flow of the base flood, it may
require the site to close or it may develop permit condi-
tions that would prevent restriction of the base flood flow.
Such conditions might include embankments or an al-
ternative unit design.
4.2.1.3   Geological Stability

Three of the management practices in  the Part 503
Subpart C regulation are designed to ensure the geo-
logical stability of an active sewage sludge unit. These
practices regulate  the location of an active  sewage
sludge unit within the vicinity of three types of geologic
features: seismic impact zones, fault areas, and unsta-
ble areas.

• Seismic Impact  Zone. For a surface disposal site
  located in seismic impact zones, Part 503  requires
  that the active sewage sludge  unit be designed to
  withstand  the  maximum recorded horizontal ground
  level acceleration.  This management practice helps
  ensure that the unit's structures, such as liners and
  leachate collection systems, will  not crack or collapse
  because of ground movement and that leachate will
  not be released due to seismic  activity.

  A seismic impact zone is an area  in which certain types
  of ground movements ("horizontal ground level  accel-
  eration") have a 10 percent or greater chance of  occur-
  ring at a certain magnitude (measured as "0.10 gravity")
  once in 250 years. The USGS keeps records  of the
  location of these areas (see also Section 4.2.2.5 for
  additional  resources). Seismic  impact zones  in the
  continental United  States are shown in Figure 4-2,
  which is based on ongoing work by the U.S. Geologi-
  cal  Service (Algermissen et al.,  1982; Algermissen et
  al.,  1990). In the western United States, earthquakes
  of large magnitude tend to occur frequently,  to  be
  associated with specific active  faults,  and therefore
  affect a relatively small geographic area. Conversely,
  in the eastern United States, large earthquakes tend
  to occur infrequently, to be independent of faults, and
  therefore affect a large geographic area.

  Various seismic design methods are available for ac-
  tive sewage sludge  units located in seismic impact
  zones. Appropriate design modifications may include
  shallower unit side slopes and more conservative de-
  sign of dikes and runoff controls. Also, contingencies
  for the leachate collection system should be consid-
  ered in case the primary system becomes ineffective.

•  Fault. A fault is a crack in the earth along which the
   ground on either side of the crack may move. Such
   ground movement is called displacement. Part 503
   requires that active sewage sludge units be located
   at least 60  meters (200 ft) from any fault  that has
   displacement  measured in "Holocene time" (recent
   geological time of  approximately the  last 11,000
   years). Requiring this distance from a fault helps en-
   sure that  the  structures of the  unit will not  be dam-
   aged if ground movement occurs  in a fault area and that
   leachate will not spread into the environment through
   faults. This  management practice must be  followed
   unless the permitting authority specifies otherwise.
                                                   35

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                                                                                                           i
                                                                                                           •ป o.
                                                                                                           5!
Figure 4-2.  Seismic impact zones (U.S. EPA, 1993).
                                                        36

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 A fault characterization will be necessary to determine
 whether an  active sewage  sludge unit  is located
 within 60 meters  (200 ft) of a Holocene  time fault.
 This investigation may involve review of available
 maps, logs, reports, scientific literature and/or insur-
 ance claims reports; an aerial reconnaissance of an
 area within a 5-mile (8-km) radius of the unit; and/or
 a walking tour of the area within 3,000 feet (914 m)
 of the unit. Two useful tools for identifying fault zones
 are (1) the U.S. Geological Survey map series iden-
 tifying the location of Holocene faults in  the United
 States (Preliminary Young Fault Maps, MF916), and
 (2)  the NAPP/NHAP high  altitude, high  resolution
 areal photographs with stereo coverage, available
 from the U.S. Geological Survey's EROS Data Cen-
 ter. If preliminary investigations indicate the presence
 of one or more faults within 3,000 feet (914 m) of the
 proposed active sewage sludge unit, further investi-
 gation will be needed to determine whether any faults
 displaced during Holocene time exist within 200 feet
 (60 m) of the unit. This investigation should be per-
 formed by a qualified professional and may involve
 subsurface exploration.

• Unstable Area. Part 503 requires that an  active sew-
  age sludge unit not be located in an unstable area. An
  unstable area is land where natural or human activities
  might occur  that could damage the unit's structures.
  Unstable areas include land where large  amounts of
  soil are moved, such as by landslides, or where the
  surface lowers or collapses when underlying limestone
  or other materials dissolve.  This  requirement protects
  the structures  of an active sewage sludge unit from
  damage by natural or human forces. Local geological
  studies may be necessary to determine that unstable
  conditions do not exist  at potential units.

 If these management practices are followed, it is less
 likely that pollutants in  sewage sludge will  be released
 into  the environment  because of  unstable geological
 conditions. Whether an active sewage sludge unit is
 within a geologically unstable area can be  determined
 using maps available through the U.S. Geologic Survey,
 Earth Science Information Center, 12201 Sunrise Valley
 Drive in Reston, Virginia. States also have geological
 surveys that map the locations of geologically unstable
 areas. (For example, in California,  guidelines are avail-
 able from the  California Division of Mines and Geology
 for identifying fault areas.)

 4.2.1.4  Protection of Wetlands

 Wetlands are areas where the soils are filled with water
 (or "saturated") during part of the year and contain vege-
 tation typically found  in  saturated soils. Examples of
 wetlands include  swamps, marshes, and bogs.  Wet-
 lands perform important ecological functions, such as
 holding flood waters, serving as habitat and  providing
sources of food for numerous species, and reducing soil
erosion. Wetlands also hold pollutants, preventing them
from contaminating other areas.

Part 503 requires that an active sewage sludge unit not
be located in a wetland, unless a permit is issued under
Section 402 (National Pollutant Discharge Elimination
System [NPDES] permit) or Section 404 (dredge and fill
permit) of the Clean Water Act. Other federal regula-
tions that may apply to surface disposal sites in wet-
lands are listed below. Figure 4-3 shows a decision tree
for considering the wetlands  requirement during the
siting process.

Any wetlands delineation  study to determine whether
wetlands are present should be conducted by a qualified
and experienced team  of experts in soil science and
botany/biology. Methods used should be in keeping with
the federal guidance in place at the time of delineation.
Criteria for identifying wetlands have been developed by
a federal task force in a manual published by the U.S.
Army  Corps  of Engineers (COE,  1989).  Proposed
changes to this manual,  however, are still  being re-
viewed. Therefore, as of  January 1993, the  EPA and
 COE agreed to use COE (1987) as guidance for deline-
 ating wetlands.

 Additional published information that may be useful in-
 cludes USGS topographic maps, National Wetland In-
 ventory maps,  USDA  Soil Conservation Service soil
 maps, and wetland inventory maps  prepared  locally.
 Some of the local COE District Offices can provide a
 wetland delineation to indicate whether all or some por-
 tion of a potential or actual active sewage sludge unit is
 in a wetland. The state agency regulating 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 wetlands may be different
 at the state level.

 Other Federal Regulations

 In addition, other federal regulations may apply to siting
 a  surface disposal site  in a wetland. These include:

 •  Sections 401, 402, and 404 of the Clean Water Act

 •  The Rivers and Harbors Act of 1989

 ซ  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
                                                    37

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                                                      Start
                                      Active Sewage Sludge Unit Appears to Be
                                        Adjacent To Or Impinging on Wetland
         A Wetland Delineation Study
            Should be Performed.
          Contact COE Regarding a
          Wetland Delineation Study
                                             Has a
                                            Wetland
                                          Delineation
                                          Study Been
                                           Performed
                                              Active Sewage Sludge
                                               Unit Adjacent to or
                                                  Impinging on
                                                    Wetland?
   No Further Action
       Required
                                                       Are
                                                     Practical
                                                   Alternative
                                                 Active Sewage
                                             Sludge Units or Surface
                                                 Disposal Sites
                                                    Available
                                               Alternative Use or
                                                    Disposal
                                                 Study Required
Cannot Build
 in Wetland
                                                      Are
                                                    Practical
                                                  Alternative
                                                 Active Sewage
                                             Sludge Units or Surface
                                                 Disposal Sites
                                                   Available
  Identify Affected Acreage and
Functions after Minimizing Impact
       and Arrange COE
           Site Visit
                                                                                                 i
                                                                               Contact State and COE to
                                                                            Determine Wetland Offset Ratios
                                                                             and Functional Rank of Offset
                                                                                       Options
                                                                                         i
                                                                                           File for Section 402
                                                                                             or 404 Permit
                                                                                       1. Impact Minimization Plan
                                                                                       2. Rebuttal of Alternatives
                                                                                         3. Wetland Offset Plan
                                                                                        4. Offset Monitoring Plan
Figure 4-3.  Wetlands decision tree for siting active sewage sludge unit (U.S. EPA, 1993).
                                                        38

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4.2.1.5   Protection of Surface Water—Collection
         of Runoff and Leachate

Runoff is rain water or other liquid that drains over the
land and runs off the land surface. Part 503 requires that
runoff from an active sewage sludge unit be collected
and disposed according to permit requirements of the
National Pollutant Discharge Elimination System and
any other applicable requirements.

Leachate is fluid from excess moisture in sewage sludge
or from rain water percolating down from the land sur-
face through an active sewage sludge unit. If an active
sewage sludge unit has a liner and  leachate collection
system, Part 503 requires that leachate be collected and
disposed according to applicable requirements. These
include NPDES permit requirements for leachate dis-
charged as a point source to surface water. The system
must be operated in accordance with applicable require-
ments while the unit is  active and for 3 years  after it
closes (or longer if required by the permitting authority).

In view of these requirements, selection  of a site on or
near surface water can compound  design and  opera-
tional difficulties and increase the difficulty in securing
permits. This should be considered during the selection
process. As part  of the site selection process, existing
surface water bodies and drainage on or  near proposed
sites should be mapped and their current and future use
considered.

4.2.1.6  Protection of Ground Water

One of the Part 503 management practices requires that
sewage sludge placed on an active sewage sludge unit
not contaminate an aquifer. An aquifer is an area below
the ground that can yield water in large enough quanti-
ties to supply wells or springs. "Contaminating an aqui-
fer" in this  instance means introducing .a  substance that
can cause the level of nitrate in ground water to increase
above a certain amount. Under this management prac-
tice nitrate-nitrogen levels  in  ground water  must  not
exceed the MCL of 10 mg/liter or must not increase the
existing concentration  of  nitrate-nitrogen in  ground
water if that concentration exceeds the MCL. Pollutants
in sewage sludge other than nitrate are addressed by
pollutant limits (see Section 3.4.2).

Part  503 also requires proof that the sewage sludge
placed on  an active sewage sludge unit  is not contami-
nating  an  aquifer. This  proof  must be either  (1)  the
 results of a ground-water monitoring program developed
 by a qualified ground-water scientist, or  (2) certification
 by a ground-water scientist that ground water will not be
 contaminated by the placement of sewage sludge on the
 active sewage sludge unit. The certification option usu-
 ally is obtainable only if the unit has a liner and leachate
 collection system because it can be difficult to certify that
 ground water will not be contaminated in the absence of
a liner, unless ground water is very deep and protected
by a natural clay layer.
Assessment of local aquifers  is an essential  step  in
helping to ensure that an active sewage sludge unit will
not contaminate an aquifer. Data collected should include:
• Depth  to ground water (including  historical highs
  and lows).
• Hydraulic gradient.

• Existing ground-water quality.
• Current and projected ground-water use.

• The location of primary recharge zones.

Sludge should not be placed where there is a potential
for direct contact with the ground-water table. Also, major
recharge zones should be  eliminated from considera-
tion, particularly sole source aquifers. As much distance
as possible should be maintained between the bottom
of the fill and the highest known level of ground water.

The structural and mineralogical characteristics (with re-
spect to nitrate-nitrogen) of any nearby aquifers should be
delineated so that the potential for contamination can be
accurately assessed. Any faults, major fractures, and
joint sets in the vicinity of an active sewage sludge unit
should be identified. Karst terrains and other solutional
formations should be avoided. In general, limestone,
dolomite, and heavily fractured crystalline rock are less
desirable than consolidated sedimentary bedrock and un-
consolidated alluvial and other unconsolidated formation.

Ground-Water Data Sources

Sources of data on ground-water quality and movement
include the  U.S Geological  Survey "Ground-water Data
Network," local well drillers, state geological surveys, state
health departments, other state environmental and regu-
latory agencies, and samplings from nearby wells. The
USGS also publishes an annual report entitled "Ground-
water Levels in the United  States" in the  Water-Supply
Paper Series. The data for this paper are derived from
some 3,500 observation wells located across the nation.

On-site Drilling

If necessary, further background  information on ground-
water elevations, fluctuations, and  quality and on the
hydraulic gradient should  be collected by performing
on-site drilling. The hydraulic gradient is equivalent to
the slope of the ground-water table (or, for an artesian
aquifer, the slope of the piezometric surface). Data on
the hydraulic gradient  helps ascertain  the  rate and
amount of  ground-water movement and whether hy-
draulic connections to surrounding aquifers exist.

The direction of ground-water flow (and thus of the
 hydraulic gradient)  can be determined  by  noting the
 depth to ground water in nearby wells or borings, calculat-
                                                    39

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  ing the elevation of the ground water, and drawing con-
  tour lines that connect wells of equal ground-water eleva-
  tions. At least  three wells  (and  normally more)  are
  needed to determine the direction of ground-water flow.
  Usually  large  units,  units  with  complex hydrogeology,
  and/or relatively flat units require more  borings than
  small units. An experienced hydrogeologist should par-
  ticipate in the  research and exploratory drilling to inter-
  pret field data. He or she can recommend the number,
  location, and type of exploratory wells needed. Table 4-2
  summarizes the methods  for collecting data from  the
                                   subsurface  and the type of information available from
                                   the methods.


                                   4.2.2  Part 258

                                   The 40 CFR Part 258 regulations promulgated in 1991
                                   under the authority of RCRA Subtitle D establish mini-
                                   mum  national  siting  requirements for  municipal solid
                                   waste, (MSW)  landfills, including MSW landfills where
                                   sewage sludge is codisposed with  household waste.
                                   Most states  have already implemented stricter landfill
  Tabla 4-3.  Summary of Methods for Collecting Data from the Subsurface (U.S. EPA, 1994)

 Method                                      Properties
                                                                  Comments
 Vertical Variations

 Drill logs
 Electric logs


 Nuclear logs


 Acoustic and seismic logs



 Other logs



 Packer Tests


 Surface geophysics


 Lateral Variations

 Poteniometric maps


 Hydrochemical  maps


Tracer tests
Geologic maps and
cross-sections

Isopach maps

Geologic structure maps


Surface geophysics
 Changes in lithology
 Aquifer thickness
 Confining bed thickness
 Layers of high/low hydraulic conductivity
 Variations in primary porosity (based on material
 description)

 Changes in lithology
 Changes in water quality
 Strike and dip (dipmeter)

 Changes in lithology
 Changes in porosity (gamma-gamma)

 Changes in lithology
 Changes in porosity
 Fracture characterization
 Strike and dip (acoustic televiewer)

 Secondary porosity (caliper,
 television/photography)
 Variations in permeability (fluid-temperature,
 flowmeters, single borehole tracing)

 Hydraulic conductivity


 Changes in lithology (resistivity, EMI, TDEM,
 seismic refraction)
 Changes in hydraulic conductivity


 Changes in water chemistry



 Time of travel between points.
Changes in formation thickness
Structural features, faults

Variations in aquifer and confining layer thickness.

Stratigraphic and structural boundary conditions
affecting aquifers.

Changes in lithology (seismic)
Structural features (seismic, GPR, gravity)
Changes in water quality/ contaminant plume
detection (ER, EMI,  GPR).
                                                                              Basic source for geologic cross sections.
                                                                              Descriptions prepared by geologist preferred
                                                                              over those by well drillers. Continuous core
                                                                              samples provided more accurate descriptions.
 Require uncased hole and fluid-filled borehole.
 Suitable for all borehole condition (cased,
 uncased, dry, and fluid-filled).

 Requires uncased or steel cased hole, and
 fluid-filled hole.
 Require open, fluid-filled borehole. Relatively
 inexpensive and easy to use.
Single packer tests used during drilling;
double-packer tests after hole completed.

Requires use of vertical sounding methods for
electrical and electromagnetic methods.
Based on interpretation of the shape and
spacing of equipotential contours.

Requires careful sampling, preservation and
analysis to make sure samples are
representative.

Requires injection point and one or more
downgradient collection points. Essential for
mapping of flow in karst.

Result from correlation features observed at the
surface and in boreholes.

Distinctive strata with large areal extent required.

See Table 5-6.
                                                                             Interpretations require verification using
                                                                             subsurface borehole data.
U.S. Environmental Protection Agency (EPA), 1994. Ground Water and Wellhead Protection. EPA/625/R-94/001. Available from CERI.
                                                          40

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siting requirements, such as restrictions on develop-
ment in  critical watershed  areas,  wellhead protection
areas, sole source aquifers, or agricultural lands. A com-
plete discussion of the siting requirements for  MSW
landfills established under  the Part 258 regulations is
beyond the scope of this manual. For further information
on the Part 258 requirements, consult EPA (1993).


4.3  Additional Considerations

In addition  to the regulatory  requirements  described
above, many other considerations govern the suitability
of a site for surface disposal of sewage sludge. These
include:

• Site life and size

• Topography

• Soils
• Vegetation

• Meteorology

• Site access

• Land use

• Archaeological or historical significance

• Costs

Table 4-3 summarizes these site  selection criteria for
surface disposal sites.

4.3.1   Site Life and Size

The site life and size are directly related. The larger the
site, the longer the site life. Both site life and size are a
function of the quantity and characteristics (especially
the percent solids) of the sludge, and the surface area
requirements of the chosen active sewage sludge unit.
Table 4-3.  Surface Disposal Site Selection Criteria
             Physical Site:           Should be large enough to accommodate waste for life of production
                                    facility.

             Proximity:             Locate as close as possible to production facility to minimize handling
                                    and reduce transport cost.  Locate away from water supply (suggested
                                    minimum  1 km) and property line (suggested minimum 250 m).

             Access:                Should be all-weather, have adequate width and load capacity, with
                                    minimum  traffic congestion.  Easy  access to major highways  and
                                    railway transport.

             Topography:           Should minimize earth-moving, take  advantage of natural conditions.
                                    Avoid natural depression  and valleys where water contamination is
                                    likely unless good control of surface  water can be assured (suggested
                                    site slope of less than 5%).

             Geology:               Avoid areas  with  earthquakes, slides,  faults,  underlying  mines,
                                    sinkholes and solution cavities.

             Hydrology:            Areas with low rainfall and high evapotranspiration and not-affected
                                    by tidal water movements and seasonal high water table.

             Soils:                  Should have a natural clay base, or clay available for liner, and final
                                    cover material available; stable soil/rock structure.  Avoid sites with
                                    thin  soil above groundwater,  highly permeable  soil  above shallow
                                    groundwater and soils with extreme erosion potential.

             Drainage:              Areas with good surface drainage and easy control of runoff.

             Surface Water:         Protection of the site against floods.  Avoid wetlands or other areas
                                    with high watertables.

             Groundwater:         No contact  with  groundwater.  Base of  fill must be  above  high
                                    groundwater table.  Avoid sites above sole-source aquifers and areas
                                    of groundwater recharge.

             Temperature:          Not within area of recurring temperature inversions.
                                                       41

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 Table 4-3.  Surface Disposal Site Selection Criteria (continued)
              Physical Site:


              Proximity:



              Access:



              Topography:




             Geology:


             Hydrology:


             Soils:




             Drainage:

             Surface Water:


             Groundwater:



             Temperature:
 Should be large enough to accommodate waste for life of production
 facility.

 Locate as close as possible to production facility to minimize handling
 and reduce transport cost.  Locate away from water supply (suggested
 minimum 1 km) and property line (suggested minimum 250 m).

 Should be all-weather, have adequate width  and  load capacity, with
 minimum traffic congestion.  Easy  access to major highways and
 railway transport.                 .

 Should minimize earth-moving, take advantage of natural conditions.
 Avoid natural depression  and  valleys where water contamination is
 likely unless good control  of surface water can be assured (suggested
 site slope of less than 5%).

 Avoid  areas  with  earthquakes,  slides,  faults,  underlying mines,
 sinkholes and solution cavities.

 Areas with low rainfall and high evapotranspiration and not-affected
 by tidal water movements and seasonal high water table.

 Should have a natural clay base, or clay available  for liner, and final
 cover material available; stable soil/rock structure. Avoid sites with
 thin soil above groundwater, highly  permeable soil  above shallow
 groundwater and soils with  extreme erosion potential.

 Areas with good surface drainage and easy control of runoff.
Protection of the site against floods.
with high watertables.
Avoid wetlands or other areas
No contact with groundwater.   Base of fill  must be above  high
groundwater table.  Avoid sites above sole-source aquifers and areas
of groundwater recharge.

Not within area of recurring temperature inversions.
 For calculation purposes, the surface area requirements
 can be divided into three categories (see Figure 4-4):

 • A. The surface area  where the  sludge  will be
  placed  (e.g.,  the area of all  the active sewage
  sludge units).

 • B. The surface  area required for spacing between
  the active sewage sludge units.

 • C. Additional surface area required for buffers, ac-
  cess roads, and soil stockpiles.

The first two are referred to collectively as the usable fill
area. They typically consume 50 percent to 70 percent
of the site's gross area (i.e., the total site area within the
surface disposal site property line).

The site size needed for a desired site life can be calcu-
lated by the following process if the total sludge volume,
active sewage sludge unit dimensions, spacing between
units, and additional area needed for buffer, etc., are known.
                      •  Step 1: Calculate the total fill volume needed over
                        the desired lifetime of the site (F) by calculating the
                        total sludge volume that must be disposed within the
                        site's desired lifetime.

                      •  Step 2: Divide F by the desired individual active sew-
                        age sludge unit volume to  calculate the number of
                        units needed (N).

                      •  Step 3: Calculate the usable fill area needed (U) by
                        multiplying  N  by the  area  of each active sewage
                        sludge unit plus the area  required  for spacing be-
                        tween each unit.

                     •  Step 4: Calculate  the  minimum gross area needed
                        by adding to U the acreage needed for buffer, access
                        roads, etc.

                     Figure 4-5 illustrates this procedure applied  to a wide
                     trench operation.
                                                     42

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                    KEY
                              = Active sewage sludge units where sludge will be placed.


                              = Area required for spacing between active sewage sludge units.
                    |  ฃI     = Additional surface area required for buffers, access roads, .and
                                soil stockpiles.


                   — —     = Boundary of active sewage sludge units.


                   ~"~""~""     = Boundary of surface disposal site.

Figure 4-4.  Schematic representation showing different types of surface area requirements at a sludge disposal site.
Similarly, the site life needed for a desjred.site size can
be calculated by the following process if the total sludge
volume, disposal.unit dimensions, and spacing between
units are known:
• Step 1: Divide the surface area of an individualactive
  sewage sludge unit plus the spacing between units
  by the usable fill area to calculate the number of units
  that can be constructed in the fill area (N),

• Step 2: Calculate total volume of all sludge units (V)
  by multiplying N by the volume of an individual  unit.

• Step  3: Calculate the site life by dividing V by the
  sludge volume generated daily or annually.
                                                    43

-------
      Given:

      1.  Sludge volume

      2.  Trench life
      3.  Tranch dimensions
      4.  Trench spacing
      5.  Buffer
60 yd'/day, 7 days/week, 29% solids
sludge
10yrs
45 ft wide x 10 ft deep x 200 ft long
10 ft of solid ground between trenches
100 ft minimum, from usable fill area to
property line
                                   = 65.7 trenches
Calculations

Step 1. Calculate total fill volume needed:

      (60 ydVday) X (365 days/yr) X (10 yrs) = 219,000 yd3

Step 2. Calculate the number of trenches needed:
          (219.000 yd3) X (27 frVyd3)
            (45ftX10ftX200ft

Step 3. Calculate the usable fill area needed:

      45 ft wide x 200 ft long trenches plus 10 ft between trenches =
              55 ft x 210 ft gross space for each trench
          (65.7 trenches) x (55 ft x 210 ft trench) = 758,835 ft2
                   (758,835ft2)
                  (43.560 ffracre)  =17-4acres

Step 4. Calculate minimum gross acreage required:

                   17.4 acres = 870 ft x 870 ft
      Minimum site size = [870 + 2 (100 ft buffer)]2 + 25% for access
       roads, dumping pad, and miscellaneoous uses = 33 acres
      IB  ซ 0.305m
      1 yd  m 1.609 m
      1 acre=0.405 ha
 Figure 4-5.  Sample calculation of surface disposal site size re-
            quired  for a wide trench  operation.  Note:  This
            method for calculating site size is only approximate.

 Figure 4-6 illustrates this calculation for a sludge-only
 narrow trench operation. Defining site life is an important
 factor in long-term planning and in estimating costs.

 The chosen active sewage sludge unit impacts site life
 and size. For example, a wide trench method  uses less
 land than a narrow trench operation, and thus provides
 a longer site  life, all other factors  being equal.  The
 sludge application rates given in Table 2-2 (see Chapter
 2) provide a means of comparing the land use  efficiency
 (and thus relative life span, all other factors being equal)
 of the various  types of active sewage sludge units.

 4.3.2  Topography

 Different types of  active sewage sludge units have dif-
ferent topographic requirements that may limit the suit-
ability of  various sites.  For example,  monofills  are
usually limited to areas with slopes greater than 1 per-
cent and  less than 20 percent because a relatively flat
site  could pond, and an excessively steep site could
Given:
1. Sludge volume   = 45 yd3/day, 7 days/week, 22% solids sludge
2. Usable fill area   = 6 acres        '
3. Trench dimensions = 10 ft wide x 5 ft deep x 120 ft long
4. Trench spacing   = 5 ft of solid ground between trenches

Calculations
Step 1. Calculate number of available trenches:

       Each trench will have area = 15 ft x 125 ft =  1,875 ft2

             Total acreage = 6 acres - 261,360 ft2

        Number of trenches = 261'360!t  = 139 trenches
                          1,875ft2

Step 2. Calculate total trench volume available:

       (139trencheS)x(10ftx5ftx120ft)xly4 =30,889 yd3
                          trench      27ft
                                                             Step 3. Calculate site life:

                                                                           30,889 yd3
                                                                          • 45 yd3/day
                                                           = 686 days = 1.9 years
                                    1 ft   = 0.305 m
                                    1yd  = 1.609m
                                    1 acre = 0.405 ha

                                  Figure 4-6.  Sample calculation of surface disposal site size life
                                             for a narrow trench operation. Note: This method for
                                             calculating site size is only approximate.

                                  erode and create operational difficulties. Dedicated dis-
                                  posal sites, on the other hand, require relatively flat land;
                                  natural slopes greater than 0.5 percent must be modified
                                  to prevent erosion (U.S. EPA, 1979). Graded or terraced
                                  sites can be used for dedicated disposal sites, but this
                                  involves  increased  earthmoving  costs.  Table  2-1  in
                                  Chapter 2 compares the ground slope requirements of
                                  the various surface disposal options.

                                  4.3.3  Soils

                                  The role of soil in surface disposal is to provide cover,
                                  when appropriate, control runoff and leachate, and serve
                                  as a bulking agent (if warranted by  the chosen active
                                  sewage sludge unit). The chemical and physical/hydrau-
                                  lic properties of a soil determine how effective it will be
                                  in performing these  roles. Relevant  soil properties that
                                  should be noted during the selection process are:

                                  • Physical/hydraulic properties:
                                    —  Grain size
                                    -  Plasticity
                                    -  Moisture content
                                    -  Sheer strength
                                    -  Permeability/hydraulic conductivity
                                    -  Atterberg  limits
                                                        44

-------
• Chemical properties:

  -pH


4.3.3.1   Physical/Hydraulic Properties

The ideal soil for an active sewage sludge unit would be
sufficiently impermeable to prevent movement of pollut-
ants in sewage sludge to  the ground water and have
appropriate chemical properties to attenuate heavy met-
als. The actual amount and type of soil needed depends
on  the type of active sewage sludge unit and the char-
acteristics  of the sludge (U.S. EPA, 1977b). In general,
however, a desirable geology will have some combina-
tion of deep [i.e., 30 feet (9 meters) or more] and fine-
grained soils. Figure 4-7 gives  the soil textural classes
and general terminology used in soil descriptions by
the U.S. Department of Agriculture, Soil Conservation
Service (SCS).

Permeability  depends  on soil texture  and structure.
Fine-grained, poorly  structured soils have the lowest
permeabilities. Table 4-4 and Figure 4-8 give qualita-
tive ranges for classifying soil permeabilities. Depend-
ing on the sludge characteristics.^ moderately low to
 low permeability soil  is desirable for an  active sewage
sludge unit.
                                          Table 4-4.  Soil Saturated Hydraulic Conductivity and
                                                    Perniability Classes (U.S. EPA, 1991)
         i.
         "A ....ft
....X...  X \ X "•• X--*- sn -A
v/'-v/ WV V'.AZ_\''
        U. S. STANDARD SIEVE NUMBERS
         10  20  40  80
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  Figure 4-7.  Soil textural classes and  general terminology
            used in soil descriptions by the U.S. Department
            of Agriculture.
                                          Class
                                                                              Values
                                          Saturated Hydraulic Conductivity
                                                                      (M/s)
Very Low (VL)
Low(L)
Moderately Low (ML)
Moderately High (MH)
High (H)
Very High (VH)
Permeability (Infiltration)

Very Slow
Very Extremely Slow
Extremely Slow
Slow
Moderately Slow
Moderate
Moderately Rapid
Rapid
Very Rapid
<0.01
0.01-0.1
0.1-1
1-10
10-100
>100

(inJtir)
<0.06
<0.01
0.01-0.06
0.06-0.2
0.2-0.6
0.6-2.0
2.0-6.0
6.0-20
>20
<0.001
, 0.001-O.Q1
0.01-0.14
0.14-1.4
1.4-14.2
>14.2

(cm/hr)
<0.15


0.15-0.5
0.5-1.5
1.5-5.0
5.0-15.2
15.2-50.8
>50.8
                                                        U.S. Environmental Protection Agency (EPA). .1991. Description  _
                                                        and sampling of contaminated soils: A field pocket guide.
                                                        EPA/625/2-91/002.

                                                        Climate also influences the soil requirements of a spe-
                                                        cific site. In an area with high rainfalls, for example, soils
                                                        with permeabilities lower than the sludge permeabilities
                                                        could result in the so-called "bathtub" effect: a situation
                                                        in which water accumulates  in the fill areas and cannot
                                                        drain. In such cases, leachate collection systems should
                                                        be designed to handle excess water.
                                           4.3.3.2  Chemical Properties

                                           Soil pH influences the ability of soils to retain or pass
                                           pollutants  (U.S. EPA, 1977a). Heavy  metals  are fre-
                                           quently held by alkali soils. Soil pH  was considered
                                           when the Part 503 pollutant limits were developed. Re-
                                           sults of field studies during which sewage sludge was
                                           applied to land with different pHs were,used in the Part
                                           503 risk assessment for use and disposal of sewage
                                           sludge. Thus, the Part 503 pollutant limits are protective
                                           for soils with different pHs. Other significant considera-
                                           tions concerning soils are compaction characteristics,
                                            drainage,  and  slope stability. Coarse-grained soils are
                                            more  suitable  for structural  applications such as road
                                            bed material, foundations, bulking soil, and daily cover.
                                            Fine-grained soils are more suitable for environmental
                                                      45

-------
                    PERMEABILITY

                   K
10'*    to'7   I0~*    ป"•    I0~*    IO'1   10 '*   W"1     I
                                      CLAYS
                TYPICAL SOIL TYPES
                                                                  SANOS, SAND T WAVELS
                                                SILTS,  SLTY SANOS.
                                                SILTY SANDY GRAVELS
                                                 I	,
                                                 I CLEAN I
                                                  CRAVELS
 Figure 4-8. Soil permeabilities of selected soils.
 applications such as bottom liners and final covers and
 caps. These are summarized in Figure 4-9.

 4.3.4   Vegetation

 The amount and type of vegetation  on a prospective
 surface disposal site should be considered in the selec-
 tion process. Vegetation can serve as a natural buffer,
 reducing dust,  noise,  odor, and visibility. However, a
 vegetated site  may require extensive  logging and/or
 clearing of vegetation, which can significantly increase
 project costs.

 4.3.5  Meteorology

 Prevailing wind direction, speed, temperature,  and at-
 mospheric stability should be  evaluated  to determine
 potential odor and dust impacts downwind of the site.

 4.3.6  Site Access

 The haul routes to the prospective sites should utilize
 major highways or arterials if possible. Potential routes
 should  be driven and studied to determine the physical
 adequacy of roadways for truck traffic; the approximate
 number of residences, parks, and schools fronting the
 roads; the probable impact on traffic congestion; and the
 potential effects of accidents. Transport through non-
 residential areas is preferable to transport through resi-
 dential areas, high-density urban areas, and areas with
 congested traffic. The access roads to the site must be
 adequate for the anticipated traffic loads. The potential
 for increased noise, dust, odor, etc., along haul routes
 can be a major public concern.

 4.3.7  Land Use

 Both current and possible future zoning of each pro-
 spective surface disposal site  should be considered.
The appropriate county or municipal  zoning authority
should be contacted to determine zoning  status or re-
strictions for each potential site. The final use for the site
 (once the site has been closed) should be considered
early in  the selection process and evaluated relative to
future zoning (see Chapter 12).

Regional development should also be considered in site
selection, and existing master plans for the area should
                     be consulted. The evaluation of current and future de-
                     velopment may present the opportunity for a more stra-
                     tegically centralized location of the site. Also, knowing
                     the projected rate and location of industrial and/or mu-
                     nicipal development is important to determine the site
                     size needed  to meet projected demands.

                     4.3.8  Archaeological or Historical
                            Significance

                     The archaeological and/or historical significance of a
                     potential surface disposal site should be determined by
                     a qualified archaeologist/anthropologist and addressed
                     in an environmental impact report. Any finds of signifi-
                     cance in relation to the archaeology or history of the site
                     should be accommodated before the site can be ap-
                     proved and construction can begin.:

                     4.3.9  Costs

                     Early in  the  selection process, surface disposal sites
                    should be screened according to their estimated relative
                    costs, including both capital and operating costs. Figure
                    4-10 shows a method for estimating site costs. However,
                    this  method  does not account for the  time value of
                    money. For most sites—particularly long-lived sites—in-
                    flation will tend to favor the selection of sites with high
                    capital costs  over sites with relatively higher operating
                    costs. In some cases, it may be necessary to compute
                    amortized capital costs.  Nevertheless, the process de-
                    scribed in Figure 4-10 is less complex and will be accu-
                    rate  in  most  cases.  Chapter  13  contains additional
                    information on the costs of surface disposal.


                    4.4   Site Selection: A Methodology for
                          Selecting Surface Disposal Sites

                    Site selection can be broken down into four basic stages:

                    • Initial site assessment and screening

                    • Site scoring and ranking

                    • Site investigation

                    • Final selection
                                                   46

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Figure 4-9.   Unified soil classification system with characteristics pertinent to surface disposal site (U.S. EPA, 1972).
                                                               47

-------
   1. Determine the capital costs (C) in dollars over the life of the
     surface disposal site. This should include primarily:
     a. Land acquisition
     b. Site preparation
     c. Equipment purchase.
   2. Determine site life (L) in years.
   3. Compute unit capital cost (P,) in dollars/y3 of sludge based on
     proposed annual sludge quantity (Q) in yd3/yr for site life.
   4. Determine total operating cost (O) in dollars over 1 year. This
     should Include primarily:
     a. Labor
     b. Equipment fuel, maintenance, and parts
     c. Utilities
     d. Laboratory analysis of water samples
     B. Supplies and materials
     f.  Miscellaneous and other.

   S. Compute unit operating cost (P2) in dollars/y3 of sludge based on
     proposed annual sludge quantity (Q) in ydvyr.
   6. Determine total hauling cost (H) in dollars over one year.

   7. Compute unit haul cost (PJ in dollars/y3 of sludge based on
     proposed annual sludge quantity (Q) in yd3/yr.
   8. Compute total annual cost (T) in dollars/yd3 of sludge.
Figure 4-10.  Method for estimating site costs. Note: This method
            does not account for inflation.

These stages are described in detail  in this section and
illustrated with an example for  Study Area X. Smaller
sites may not need as detailed a selection process.
4.4.1  Step 1: Initial Site Assessment and
        Screening

The purpose of this phase is to develop a list of potential
sites  that can be evaluated  and  rapidly screened to
produce a manageable number of candidate sites. Infor-
mation used in this  phase is generally available  and
readily accessible. This phase can be divided into seven
steps, described below.

Step 1-1: Determine factors that will constrain site se-
lection. Consider:

• Federal, state, and local regulations.

• Physical limitations (e.g., ground-water depth, maxi-
  mum slope).

• Demographic limitations  (distance to nearest resi-
  dence, land-use factors, etc.).

• Political limitations (public  reaction, special interest
  groups, budget management).
Step 1-2: Establish suitable study area(s):

•  Determine maximum radius of study area based on
   haul distance(s) from wastewater treatment plant(s)
   and/or centroid of potential service area.

•  Use transparent (mylar) overlays to designate areas
   that must be excluded  due to regulatory constraints
   or that are problematic due to other considerations.
   Tables 4-5 and 4-6 list exclusionary and low suitability
   criteria for sewage sludge surface disposal sites and
   codisposal sites, respectively.

•  Place shaded mylars of these  unsuitable or low suit-
   ability areas on the study area map. The unshaded
   area may be considered generally  suitable for sur-
   face disposal of sewage sludge. Figure 4-11 provides
   an example of an overlay map for Study Area X using
   three shaded mylars. (Only three mylars were  used
   in the illustration to  keep  it simple. In reality, several
   mylars are often used.)

Step 1-3: Identify potential  candidate surface disposal
sites:

•  Inform  local realtors.

•  Investigate past site inventories.

•  Study maps or aerial photographs.

•  Traverse roads in high probability areas and look for
   "For Sale" or "For Lease" signs.

Table 4-5.  Exclusionary and Low Suitability Criteria for
          Sewage Sludge Surface Disposal Sites


Exclusionary Criteria

• The presence of a surface disposal operation at the site could
  adversely affect a threatened or endangered species listed
  under Section 4 of the Endangered Species Act.
• Placement of sewage sludge on an active sewage sludge unit
  would restrict the flow of a base flood.
• Site is located within 60 meters of a fault that has displacement
  measured in "Holocene time."
• Site is located in a geologically unstable area.
• Site has wetlands.
Low Suitability Criteria

• Located within a 100-year flood zone.
• Located within a seismic impact zone.
• In the recharge zone of a sole source aquifer.
• Inappropriate slope.
• Other undesirable geological features (karst, fractured bedrock
  formations).
• Dense population.
• Undesirable soil (shallow, high organics, permafrost areas).
• On or near surface waters.
                                                        48

-------
Table 4-6.  Exclusionary and Y-ow Suitability Criteria for
           Codisposal Sites
Exclusionary Criteria

•  Site is located within 10,000 feet (3,048 meters) of the end of
   any public airport runway used by turbojet aircraft or within
   5,000 feet (1,524 meters) of the end of any public airport
   runway used by only piston-type aircraft and a codisposal
   operation on the site might pose a bird hazard to aircraft.

•  Site is located within a 100-year flood  plain and the presence of
   a codisposal operation might restrict the flow of the 100-year
   flood, reduce the temporary storage capacity of the floodplain,
   or result in a washout of the municipal solid waste.

•  Site contains wetlands (unless the site is located in an approved
   state3 and the owner/operator can demonstrate that no practical
   alternative not involving wetlands exists and fulfil other
   demonstration criteria).

•  Site is located within 200 ft (60 m) of a fault area that has
   experienced displacement within the Holocene time
   (approximately the last 11,000 years) (unless the site  is located
   in an approved state3 and the owner/operator can demonstrate
   sufficient structural integrity of the facility to ensure  protection of
   human health and the environment in  the event of a
   displacement).

•  Site is located in a seismic impact zone (unless the site is
   located in an approved state3 and the owner/operator can
   demonstrate that all containment structures are designed to
   resist the maximum horizontal acceleration).

•  Site is located  in an unstable area (unless the owner/operator
   can demonstrate that engineering measures have been
   incorporated into the unit1 s design to ensure the integrity of the
   codisposal operation's structural components).

 Low Suitability Criteria

 •  Poses a hazard to a threatened or endangered species.

 •  Inappropriate slope.

 •  Dense population.

 •  Undesirable soil (shallow, high organics, permafrost areas).

 • On or near surface waters.

 • In the recharge zone of an aquifer.	

 a A state approved by EPA for primary implementation of the Part 258
 regulations.
Step 1-4: Assess economic  feasibility  (ballpark esti-
mate based on experience, rule of thumb, judgment) of
candidate sites including:

• Haul distances

• Rough estimate of site development cost

• Quantity of sludge

• Operating hours per week for equipment and personnel

Step 1-5:  Perform preliminary site investigations using
existing information and tabulate information.  Pertinent
information includes:

• Location

• Zoning

• Land use (on  and near site)

• Access

•  Haul distance and routes

• Topography

•  Soil characteristics

•  Usable area of site

•  Drainage basin

Table 4-7 shows an example of tabulated site  investiga-
tion information  for 13 candidate sites for Study Area X.

 Step 1-6: Eliminate less desirable sites based on regu-
 latory, economicj and technical considerations.

 Step 1-7: Obtain public input via the public participation
 program (see Chapter 5). For example,  a kick-off meet-
 ing would help to determine the attitude of the citizenry
                                  UNSUITABLE 3WLS

                                  TOPOGRAPHIC LWrTATlONS
                                  oMuiAsut oaxocv
                                        sire
  Figure 4-11.  Initial assessment with overlays for Study Area X.
                                                            49

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early in the process. Area residents also may assist in
identifying candidate sites.

4.4.2  Step 2: Site Scoring and Ranking

This section describes a quantitative approach to scor-
ing and ranking sites. This approach involves!defining
objectives, defining criteria to meet those objectives,
specifying the relative importance of the objectives and
criteria, and then assigning scores—weighted according
to the relative importance of each criterion and its overall
objective—that indicate the ability of each candidate site
to fulfil each criterion. The individual scores are then
added to produce a total score for each site that can then
be used to rank the sites.

This approach may be more extensive than necessary
for small sludge surface disposal sites. In such cases, a
qualitative system (e.g., using terms such as suitable,
marginally suitable, and not suitable in lieu of numerical
ratings) may be more appropriate. Table 4-8 illustrates
how the site  scoring and ranking process described
below was applied to the four candidate sites for Study
Area X that remained after the less desirable of the 13
original sites were eliminated during Step 1-6 based on
regulatory, technical, and economic considerations.

Step 2-1: Determine attainable objectives for the site
based on the following considerations:

• Technical considerations:
  - Haul distance
  — Site life and size
   - Topography
   - Soils and geology
   - Ground water
   — Soil quantity  and suitability
   - Vegetation
   - Environmentally sensitive areas
   - Archaeological or historical significance
   - Site  access
   - Land use

 • Economic considerations

 • Public  acceptance considerations

 Column 1 of Table 4-8 shows some examples of objec-
 tives.

 Step 2-2: List these objectives by order of importance.
 Assign a value (e.g., on a scale of 1 to 10,1 to 100, or
 1 to 1,000) to each objective to reflect its relative impor-
 tance. (Column 2  of Table 4-8 rates the Column 1 objec-
 tives on a scale of 1 to 1,000.) Discard any objectives
that  appear insignificant in light  of a  very  low rating
relative to other objectives.

Step 2-3: For each objective, develop criteria to meas-
ure the ability of a site to attain the objective. Column 3
of Table 4-8 lists criteria for the Column 1 objectives.

Step 2-4: Assign a numerical value on a scale of 1 to
10 to the criteria for each objective to reflect their relative
ability to contribute to the attainment of  the objective,
rather than their individual significance. Add the values
assigned to all criteria for a particular objective. Column
4 of Table 4-8 shows the relative values assigned to the
Column 3 criteria and the  addition of values for the
criteria within each objective.             '"
                                        !•
Step 2-5: For  each  criterion,  multiply  its numerical
value  by the overall rating for the objective and divide
by the total of all criteria values within  that objective to
get the maximum score that may be assigned to that
criterion (see Column  5 of Table  4-8).  For example, to
obtain the maximum score for the first criterion ("ground-
water  pollution hazard") of the  first objective ("the site
must not endanger public health") listed in Table 4-8, the
following calculation was performed:
                  10x1,000
                      34
 = 294
 The maximum score for each criterion is thus a fraction
 of the total score for the objective in direct proportion to
 the criterion's relative ability to contribute to attainment
 of the objective. The  maxjmum scores for all criteria
 within an objective should total to the relative overall
 rating for the objective (Column 2 of Table 4-8).

 Step 2-6:  For each criterion, assign  a rating from 1 to
 10 to each site to indicate the site's potential to satisfy
 that criterion. (If a site cannot meet an objective, the site
 should be eliminated from further consideration.) Columns
 6a, 7a, 8a, and 9a show values assigned for sites 1, 2, 3,
 and 4, respectively. These values must now be weighted
 to reflect the relative importance of  the objective and
 the  individual criterion. This  is done  by multiplying the
 rating by the maximum score for that criterion (Column
 5 of Table 4-8) and then dividing the total by the relative
 ability of the criterion to fulfil  the objective (Column 4 of
 Table 4-8). For example,  a rating of 7 was assigned to
 the  ability of site S-5 to satisfy the first criterion for the
 first objective. The following calculation was then per-
 formed to yield a weighted score of 206:
                    7x294
                       10
= 206
 Columns 6b, 7b, 8b, and 9b of Table 4-8 show the
 weighted scores calculated for the four candidate sites
 in Study Area X.
                                                     51

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-------
This scoring system works best if all sites are compared
one criterion at a time. Different specialists should be
used to score the sites under criteria involving their area
of expertise. For example, land use planners should be
used to score those criteria related to land use.

Step 2-7: For each site, add all the individual scores to
get a total score for the site (see bottom row of columns
6b, 7b, 8b, and  9b in Table 4-8). These totals can be
compared to rank the overall and relative suitability of the
various candidate sites. For example, the sites in Table
4-8 would be ranked S-11, S-13, S-5, and S-10 in order
from most suitable to least suitable for a sludge surface
disposal site considering all objectives and criteria.

4.4.3  Step 3: Site Investigation

Step 3-1: Investigate four to six candidate sites and
identify site-specific problems. Field investigations (see
Chapter 6) may be appropriate to supplement informa-
tion from existing sources. In particular, it may be desir-
able at this  stage to  perform initial hydrogeological
investigations on the primary candidate sites. This in-
vestigation can begin with a preliminary reconnaissance
visit to each site to observe aspects such as:

• Site topography

• General geomorphic features

• Bedrock exposure

• Degree of soil development

• Seeps and springs

• Potentially impacting activities (e.g., clear cutting)

• Vegetation types

• Wetlands potential

To perform a hydrogeological investigation that involves
drilling, an option for the site must be obtained. Because
option negotiations are not always successful, it may be
necessary to pursue negotiations for two to three times
as many sites as the evaluation team wishes to actually
investigate.

Performance of a conceptual design (see Step 4-1), and
development of a  refined  cost estimate based on this
design, may also be appropriate for some or all of the
candidate sites during the  site investigation stage.

Step 3-2:  Rescore and rank sites based on results.
Once the results of the hydrogeological investigation
have  been  obtained, the ranking of candidate sites
should be reexamined and modified as  appropriate  to
incorporate the site-specific results obtained during the
hydrogeological investigation. Any sites that are unsuit-
able hydrogeologically should be eliminated from further
consideration.

Step 3-3: If required or appropriate, input site selection
findings of top site(s) into an environmental impact re-
port. Environmental impact reports are required in cer-
tain states  (e.g.,  New York).  Environmental impact
reports may also be appropriate under certain circum-
stances such as for environmentally sensitive sites or
for sites where there is a high level of public concern.

Step 3-4: Obtain additional public input.

4.4.4  Step 4: Final Selection

Step 4-1: For each candidate site, develop a concep-
tual design that is compatible with sludge and site char-
acteristics (see Chapter 3)  (or review and revise the
conceptual designs if they were already developed un-
der Step 3-1). A conceptual design should first establish
site buffers,  site facilities, site volume, site life, and the
overall landfill footprint. Once these have been estab-
lished, a preliminary excavation plan and a final grading
plan can be developed using conventional civil  engi-
neering   and  computer-aided  design   and   drafting
(CADD) tools. The designer can then readily determine
the landfill capacity (or airspace) by using CADD tools
to compare the excavation and final grading plans. The
capacity calculation can in turn be used to determine the
soil balance, the overall site life, and other site features.
CADD tools  can also be used to delineate the shape of
the surface disposal site to better enable public percep-
tion and interpretation.  Finally, the conceptual design
can serve as the basis for a cost estimate. A detailed
preliminary cost estimate can be developed to address
capital costs (liner systems, excavation, roads, facilities,
etc.)  and  operating  costs  (equipment,  personnel,
leachate treatment/disposal, etc.).

Step 4-2: Evaluate the options for using the closed site
and select the most appropriate use for each candidate
site.

Step 4-3: Evaluate life cycle costs in detail  for each
candidate site.

• Site capital cost

• Site operating cost

• Hauling cost

Tables 4-9 and 4-10 show the capital and operating cost
estimates for the four sites under final consideration at
Study Area  X.  (In  this example, hauling costs are in-
cluded as part  of operating costs.) The total cost was
calculated using the following method to determine pro-
rated cost ($/yd3) over the life of the site  based on the
projected sludge volumes.
                                                   53

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Table 4-9. Capital Cost Estimates for Four Study Area
Description
Land Acquisition
Number of acres
Cost per acre
Purchase price
Site Development Costs
Initial site preparation
Clearing and grubbing
Fence and gate
Access roadway (onsite)
Leachate collection system
Storm water management
Reconstruct primary access roadway
Equipment storage shed
Utilities
Monitoring
Subtotal
Engineering Surveying Subsurface Exploration and
Permits (20%)
Contingency (1 0%) of Land Acquisition and Site
Development Costs
Equipment
Backhoe Loader
Total Capital Cost
Estimated Site Life (yrs)
Unit Cost ($/yef) based on 18,000 ycf/yr
Annual Unit Capital Cost 8% over Site Life ($/yo3)
X Candidate
S-5

20
6,600
132,000

100,000
240,000
20,000
16,000
4,000
30,000
—
30,000
4,000
8,000
621,600
124,000
62,000

180,000
987,600
10
5.49
0.89
Sites
Site
S-10

37
16,000
592,000

60,000
4,000
24,000
32,000
—
40,000
—
30,000
6,000
8,000
796,000
159,200
79,600

120,000
1,154,800
12
5.35
0.79
No.
S-11

25
4,000
1,000,012

60,000
6,000
20,000
6,000
50,000
30,000
—
30,000
4,000
8,000
314,000
62,800
31,400

180,000
588,200
10
3.27
0.53

S-13

30
16,600
498,000

80,000
10,000
6,000
24,000
—
60,000
200,000
30,000
6,000
8,000
922,000
184,400,
92,200

45,000
1,243,600
12
5.76
0.85
          1 yd3
          1 ac
0.7646 m3
0.4047 ha
   Total Capital Costs =
   Total Operation and =
   Maintenance Costs

Total Unit Capital Cost =

   Total Unit Operation =
     and Maintenance
                Cost
        Land Acquisition Cost +
        Site Development Cost +
        Engineering and
        Contingency (20% + 10%
        of land acquisition and
        development costs) +
        Equipment Purchase Cost
        Site Operation and
        maintenance Costs +
        Sludge Handling Cost
        Total Capital Cost/18,000
        yd3/yr
        Total Operation and
        Maintenance Cost/18,000
        yd3/yr
   Annual Unit Capital
          Cost ($/yd3)

     Total Unit Annual
          Cost ($/yd3)
Total Unit Capital Cost
($/yd3) amortized at 10%
over site life
Annual unit capital cost
($/yd3) + Annual Operation
Cost ($/yd3)
Step 4-4: Evaluate local government policies and ob-
tain public input. A public hearing may be scheduled to
receive final comments from local government officials
and the public.

Step 4-5: Select  site  and list alternative  sites. In the
example  Study Area X, the data affecting  the final site
selection were summarized in a table (Table 4-11). Site
                                                  54

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Table 4-10. Operating Cost Estimates for Four Study Area X Candidate Sites
Site No.
Description
One full-time equipment operator: Cost includes an
allowance of 30% for fringe benefits
Equipment operation and maintenance
Site operation and maintenance
Leachate haul costs
Cover material purchase
Temporary road surfacing, access,
cleaning
and highway
Ground-water monitoring samples
Subtotal of site costs
Sludge hauling cost
Total operating cost/yr
Unit cost ($/yo3) based on 18,000 ycP/yr
Table
Map
Ref.
S-5
S-10
S-11
S-13
4-11. Final Site Selection
Site Name/Location
Alton Street Site
Hunter Road Site
Harrington Blvd. Site
Gilford Road Site

Scoring
System
Value
1,773
1,538
2,534
2,239

Type of
Surface
Disposal Site
Area fill mound
Wide trench
Area fill mound
Wide trench
S-5
$30,000
$30,000
$10,000
$2,000
$50,000
$40,000
$6,000
$168,000
$30,000
$198,000
$11.00

Proposed Final
Site Use
Open space
Return to natural
Pasture
Park
S-10
$30,000
$30,000
$10,000
—
$30,000
$4,000
$104,000
$300,000
$404,000
$22.44

S-11
$30,000
$30,000
$6,000
$2,000
$80,000
$30,000
$4,000
$182,000
$50,000
$232,000
$12.88

S-13
, $30,000
$30,000
$8,000
— •
$16,000
$4,000
$88,000
$150,000
$238,000
$13.22

Site Total Annual
Life Cost ($/yd3)a
10
state 12
10
12
yrs
yrs
yrs
yrs
11.89
23.23
13.41
14.07






Public
Acceptance
Ranking"
3
2
4
1
8 Sum' of annual capital costs (at 10 percent over site life) and operating costs.
b Provided from attitude survey taken at public meetings; lower numbers represent less opposition.
1 yd3 = 0.7646 m3
S-13 was selected based on its (1) top public accep-
tance ranking, (2) longer life, and (3) completed site use
as a needed park. Although site S-13 was not the top-
ranked site technically, it was technically acceptable.
Also, its cost was  relatively high, but the operating
agency decided to  absorb the extra cost  due to the
obvious site benefits.

Step 4-6: Acquire site. The following options are avail-
able:

• Option to purchase and subsequent execution (await
  site approval).

• Outright purchase (after site approval  by regulatory
  agency and local jurisdiction).

• Lease.

• Condemnation and/or other court action.

• Land dedication.
Purchasing a site is generally more advantageous than
holding  a  long-term lease  because  the  managing
agency's responsibility normally extends well beyond
the site life. Certain advantages may also be gained by
leasing with an option to buy the site at the time of permit
approval. This option ensures that the land will be avail-
able when the  facility planning process is completed. It
also allows time for the previous  owner to gradually
phase out operations, if necessary.
4.5   References
 1. Algermissen, ST., et al. 1990. Probabilistic earthquake and velocity
   maps for the United States and Puerto Rico. Miscellaneous field
   studies map MF-2120. Washington, DC: U.S. Geological Survey.

 2. Algermissen, ST., et al. 1982. Probabilistic estimates of maximum
   acceleration and velocity in rock in the contiguous United States.
   Open-file report 82-1033. Washington, DC: U.S. Geological Survey.
                                                      55

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3. U.S. Army Corps of Engineers. 1989. Federal manual for identi-
   fying and delineating jurisdictional wetlands: Cooperative techni-
   cal publication.  Federal  Interagency  Committee  for Wetland
   Delineation, U.S. Army Corps of Engineers, U.S. Environmental
   Protection Agency, U.S. Fish and Wildlife Service, and U.S. De-
   partment of Agriculture Soil Conservation Service. Washington, DC.

4. U.S. Army Corps of Engineers. 1987. Corps of Engineers wet-
   lands delineation manual. Technical report Y-87-1. Vicksburg,
   MS: Waterways Experiment Station.

5. U.S.  EPA.  1994.  Ground  Water  and Wellhead Protection.
   EPA/625/R-94/001.

6. U.S. EPA. 1993. Technical manual for solid waste disposal facility
   Criteria: 40  CFR Part 258.  EPA/530/R-93/017  (NTIS PB94-
   100450). Washington, DC.
 7. U.S. EPA. 1991. Description and sampling of contaminated soils:
    A field pocket guide. EPA/625/2-91/002.

 8. U.S. EPA. 1985. Criteria for selecting a site for the land disposal
    of hazardous wastes. EPA/600/2-85/018.

 9. U.S. EPA. 1979.  Process design manual for sludge treatment and
    disposal. EPA/625/1-79/011, Cincinnati, OH.

10. U.S. EPA. 1977a. Process design manual for land treatment of
    municipal wastewater. EPA/625/1-77/008. Cincinnati, OH (Octo-
    ber), pp. C-13 toC-19.

11. U.S. EPA.  1977b.  Database for standards/regulations develop-
    ment for land disposal of flue gas cleaning sludges. EPA/600/7-
    77/118. Cincinnati, OH. pp. 146-148.

12. U.S. EPA.  1972. Sanitary landfill design and operation. Report
    No. SW65ts. Washington, DC.  p.17
                                                              56

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                                             Chapter 5
                                 Public Participation Programs
5.1   Introduction

Public participation is very important to the success of
sludge use or disposal projects. A community's willing-
ness to cooperate with a project depends on:

• Its perceptions of the need for, costs of, and benefits
  of the project.

• The degree to which the community feels it has been
  kept honestly informed and has  had a chance to
  express its concerns and have its ideas incorporated
  into the planning and operation.

The purpose  of a public participation program (PPP) in
surface disposal is to inform and involve the public. Plan-
ning for public participation in a surface disposal project
involves careful  and early evaluation of what should be
communicated, to whom, by whom, and when. This chap-
ter summarizes  the major considerations involved in im-
plementing a successful program, including the objectives
and value of a public participation program, PPP partici-
pants, the design and timing of a program, and areas of
public concern in surface disposal.

5.2  Objectives

The objectives of a public participation program are:

• Promoting  full and accurate public understanding of
  the need for surface disposal, the active  sewage
  sludge unit selected, and the advantages and disad-
  vantages of the project.

• Keeping the  public well-informed on  the status of
  various planning, design, and operation activities.

• Soliciting from concerned citizens their relevant opin-
  ions, perceptions, and suggestions involving surface
  disposal.

The key to achieving these  objectives  is continuous
two-way communication between surface disposal site
planners/designers/qperators  and the  public. A
common problem for public officials is the assumption
that educational, informational, and other one-way com-
munication techniques provide for an  adequate  dia-
logue. When designing a public  participation program,
sufficient mechanisms must be provided for meaningful
public input into the decision process (see Section 5.5).
A PPP will increase the lead time required to select,
design,  and construct a surface disposal  site. This
must be considered when  initially determining  the
need for a new site.

5.3   Value of a PPP

Public participation has become virtually essential to the
success of surface disposal projects. Public  resistance
to a  project, due either to legitimate concerns that are
not addressed or to misperceptions or anger resulting
from lack of involvement, generally will either make the
project impossible or at least more costly and difficult.
The  process of involving the public does require some
investment of cost and time, but this likely will be far less
than the potential expense and  delays risked by not
involving the public. A PPP is well worth the extra cost
as more expensive project delays are probable if an irate
populace becomes involved late in the process. The PPP
process contributes to an effective decision-making proc-
ess.  The advantages of a PPP include (Canter, 1977):

• An increased likelihood of public approval or accep-
  tance for the final plans.

• A method of providing useful information to decision-
  makers, especially where values or factors that are
  not easily quantified are concerned.

• Assurance that all  issues are fully and carefully con-
  sidered.

• A  safety valve  in  providing  a forum whereby sup-
  pressed feelings can be aired.

• Increased accountability by decision-makers.

• An effective mechanism to encourage decision-mak-
  ers to be responsive to issues beyond  those of the
  immediate project.

5.4   PPP Participants

5.4.1  Public Participants

The  success of a public participation program depends,
in part, on who  is  involved.  Failure to involve  the
appropriate people at the appropriate times can result in
                                                  57

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unnecessary additional costs or time delays by increas-
ing public concern and inciting public anger. Therefore,
PPP design requires an effective publicity campaign
that will reach the appropriate people at the propertlmes
throughout the planning process. Special efforts should
be made to involve groups and individuals who:

•  Have demonstrated an interest in environmental affairs.

• Are  likely to be directly affected by  the proposed
   surface disposal project.

Table 5-1 lists the types of groups and individuals who
should be contacted regarding a  public participation
program. A list of names and addresses of interested
persons and organizations in these categories for formal
and informal notifications and contacts should be devel-
oped at the beginning of a project. Identifying  specific
groups and individuals as targets for public involvement
efforts helps to focus time and  money on the most likely
participants, to focus the objectives of the PPP, and to
interpret how well the various involvement mechanisms
are working.

In addition, a special effort should be made to ensure
that the particularly important people, (such as influential

Table 5-1.  Potential PPP Participants
The following groups and individuals should be contacted as part
of any PPP:
• 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 industial associations
• Property owners and users of proposed sites and neighboring
  areas
• Service clubs and civic organizations, including the League of
  Women Voters, etc.
• Media, Including newspapers, radio, television, etc.
The following groups can 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, possibly including various
  urban groups, economic opportunity groups, political clubs and
  associations, etc.
ซ Labor Unions
• Key Individuals who do not yet express their preferences
  through, or participate in, any groups or organizations
individuals,  people who are most likely to have strong
feelings  about the site, and  the media) are not only
informed, but convinced of the validity of the  surface
disposal project.  It is crucial that as many of these key
groups as possible support the surface disposal project
and speak out in favor of it during the public participation
program. Also, it is important that key participants get
involved as early as possible, to avoid situations where
previously disinterested individuals develop strong feel-
ings about  the project when  decisions  have  already
been made.

Local officials should be notified about the project before
the issue enters  the field of public debate. This allows
them to form a more objective opinion about the project
and prepares them for  inquiries from the public.

5.4.2  Program Staff

The success of a public  participation program also hinges,
in part, on the attitudes, abilities, and experience of the
program staff responsible for communicating with the
public, either through preparation of informational mate-
rials or in live dialogue. One of the most important factors
in any PPP is the ability to establish the public's trust. A
PPP that fails to establish the public's trust may do more
damage than no PPP at all. Trust is the basis on which
program staff and participants can have a meaningful
and constructive dialogue on the project and associated
concerns. Without trust, the public may well maintain an
attitude of hostility and  resistance. To establish trust, the
PPP staff, either individually or collectively will  need to
have good  technical understanding  of the project and
good communication skills. Some abilities and attitudes
that help to build trust include (U.S. EPA, 1988):

• Involving all parties that may have an interest or stake
   in the outcome.

• Involving  the public before decisions have been made.

• Truly listening to the public's concerns and  feelings
   about the project. Being a good listener involves rec-
   ognizing  and  respecting people's feelings,  demon-
   strating  that you have  heard and understood what
   people have said, recognizing "hidden agendas" and
   symbolic meanings  (for example, property owners
   near a surface disposal  site may sound alarms about
   ground-water  pollution when their major concern is
   actually property value depreciation), and adopting a
   truly accepting, compassionate, and nonjudgmental
   attitude toward the speaker.

• Respecting the public's concerns, even if these con-
   cerns have no scientific basis.

• Be the first source  of information and maintain the
   trust of the media. Tell  the good news and the bad,
   and how the project will minimize the bad.
                                                      58

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• Being honest, frank, and open. This includes admit-
  ting when you,are uncertain, do not know, or have
  made a  mistake, and getting back to people with
  answers. It  also involves disclosing information as
  soon as  possible. Any potential problem that is not
  publicly addressed at the outset of a project will likely
  be brought to the attention of the media,  resulting in
  the possible reduction of public support and the loss
  of the project leadership's credibility.

• Communicating  in  nonscientific language that the
  public can readily understand.


5.5  Design of a  PPP

The PPP should be tailored to each particular situation
in terms of cost and  scale. A certain minimum effort
should be put into every participation program but, within
a basic framework, appropriateness  and flexibility are
the keys. A common sense approach  in determining the
number and frequency of public involvement mecha-
nisms is recommended. When budget or time restric-
tions  prohibit  development of an ideal  program, it is
more important to apply participation techniques that are
highly effective. Table 5-2 indicates the relative effective-
ness of the PPP activities  suggested  in this section.

Public participation is critical at various stages of the sur-
face disposal site development process. Most involvement

Table 5-2. Relative Effectiveness of Public Participation Activities
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.  This
section discusses the critical planning stages where public
input is particularly important and the appropriate public
participation mechanisms at each stage.

5.5.1   Initial Planning Stage

During the initial planning stage, the scope and scale of
the entire PPP should be established, and the organiza-
tion of PPP components and the use of PPP mecha-
nisms should be determined. There are two  general
types of PPP mechanisms:

• Educational/informational activities that represent one-
  way communication from officials to the  public.

• Interaction techniques that promote two-way commu-
  nication.

The major activities during the initial planning stage are
mostly informational/educational. The officials doing the
communicating at this point may be operating authori-
ties, elected  officials, engineering consultants,  or even
public relations firms. These officials should inform the
public about the:                •'.'.'.-
                                                     Communication characteristics
Public participation technique
Publ Ic hearings
Publ Ic meetings
Advisory Committee meetings
Hall ings
Contact persons
Newspaper articles
News releases
Audio-visual presentations
Newspaper advertisements
Posters, brochures, displays
Workshops
Radio talk shows
Tours/field trips
Onbud sm an
Task force
Telephone line
Level of
publ ic
contact
achieved
H
H
. L
M
L
H
M
M
H
H
L
It
L
L
L
11
Ability to
handle Degree of
specific two-way
interest communication
L
L
H
H
M
L
L
L
L
L
II
M
H
H
H
M
L
M
H
L
II
L
U
L
I
. L
M
M
H
H
H
M
I ป low value
M ป medium value
H ป high value
                                                    59

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• Purpose of the surface disposal project.
• Rationale for selecting surface disposal over alterna-
  tive  use or disposal practices  such as incineration
  and  land application.
• Need for the project in the community.
• General design and operation principles.
• Projected final land use.
• Potential for creation of new jobs, etc.
The public information products will likely also need to
include basic information explaining what sludge is, how
it is generated, and how it relates to the public demand
for clean water.
As initial site investigations get underway, two-way pub-
lic involvement activities become important. The follow-
ing  mechanisms should  be organized during this stage
(CH2M Hill, Donahue and Associates, et al.,  1977):
• Public officials workshop.  The  purpose of this
  workshop is to acquaint the concerned officials with
  the technical considerations relevant to the surface
  disposal project and to obtain input from local officials
  on appropriate timing of activities and areas of  po-
  tential public concern.
• Advisory Committee. The role of this group is to
  help organize citizen support for the proposed plan,
  to act as a sounding board in providing citizen reac-
  tions to various proposals, and to take an active part
  in decision-making. The group should include repre-
  sentatives of local government departments, commu-
  nity  organizations, private  industry, and others.
  Consultant progress reports can be presented during
  these meetings and later publicized.
• Mailing list. Comprehensive mailing lists  are  the
  foundation of an information output program. To be
  effective, they must represent a broad cross-section
  of groups and individuals and be frequently expanded
  and  updated.
• Liaison/contact persons.  Liaison/contact  persons
  are responsible for receiving  input,  answering  ques-
  tions, expanding mailing lists, and generally being re-
  sponsive.  They keep logs of  all questions and refer
  issues of general concern to the appropriate people for
  consideration. These positions should be held by per-
  sons who are actively involved in the surface disposal
  decision-making process; e.g.,  a consulting engineer,
  public works official, or other comparably informed in-
  dividuals.  In large municipalities it may  be advanta-
  geous to hire an individual to handle public  relations.
• Media program. This involves organizing an  effec-
  tive publicity campaign using various media. The me-
  dia should be  contacted as  early as possible and
  every effort should be made to convince them of both
  the need for and effectiveness of a surface disposal
  project before the topic becomes an emotional issue.
  In this way, objective treatment of the issue by the
  media is more likely. Again, the extent of this program
  depends upon the particular situation. Various chan-
  nels include:
  - Newspapers. A series  of informative  articles on
     surface disposal can be timed to appear through-
     out the project to sustain public interest and serve
     as an educational tool. Each article or news re-
     lease can also transmit hard news such as notices
     of public meetings, or articles describing events at
     public meetings.
  — Television. This method can be very expensive, but
     can also be very useful in transmitting information.
     Through careful planning, some free coverage  of
     the project can probably be arranged through news
     programs,  public service announcements, or sta-
     tion editorials.
  - Advertisements. Full-page newspaper advertise-
     ments could be used to relate complex information.
     They can incorporate a mailback feature to high-
     light citizen concerns, and solicit participation  of
     interested individuals.
  - Posters, brochures, or displays.  These can be
     highly effective educational tools, especially when
     particularly creative and put in high traffic areas or
     given wide distribution.
  - Radio advertisements or informational talks. The
     radio can be used to advertise events  or information
     in much the same way that newspapers are used.

• Classroom educational materials. This can be an
  effective way of educating school children and  their
  parents.  Presentations can be made in individual
  schools or, more  economically, special  newsletters
  and brochures  can be designed for use in schools
 ' and distribution to other audiences.

5.5.2  Site Selection Stage

The major activities of  the  initial planning stage are
preparatory mechanisms for the  site selection stage.
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, design
and operation procedures, etc.

Most public interest and involvement—including the most
vocal and organized protests—occur during the site
selection stage. Therefore, the major thrust of the  PPP
should come during this stage, with a particular empha-
sis  on two-way communication including:
                                                   60

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• Public meetings. These are an excellent mechanism
  for providing public information, receiving input, and
  achieving one-to-one contact between consultants,
  local officials, and the public.  They are normally less
  structured than public hearings and therefore, more
  likely to result in dialogue. Generally, a series of such
  meetings is held in different locations within the plan-
  ning area to provide maximum opportunity for atten-
  dance by the public. These are a good arena for the
  use  of  audiovisual presentations. These meetings
  work especially well when there are concrete issues
  to be discussed, and should be timed to coincide with
  particularly critical  periods  in the decision-making
  process. For example, the public at these meetings
  could screen the site selection criteria or even rate
  the candidate  sites against  those selected criteria.
  The more successful meetings are usually a result of
  heavy advance work. Overcoming  public apathy can
  be  difficult, but is critically important in these early
  planning stages. Consultant contracts should clearly
  .specify the number of public meetings  to be held
  because it is often costly and time-consuming to pre-
  pare for them.

 • Workshops. Generally,  these have positive results
  although they  are  not widely used  because of low
  turnout. Such  groups  usually involve citizens being
  given courses of instruction by agency staff, and then
  addressing specific work efforts on the basis of such
  instruction. Basically workshops are an  educational
  tool with interaction features.

 • Radio talk-shows. Many communities have local ra-
   dio talk shows where residents can call in and voice
  their opinions. The consultant and/or a local  official
   could give a  short presentation on  the surface dis-
   posal plan and then field callers' questions. This is a
   good opportunity to dispel some misinformation, but
   views  of the  callers  do not necessarily  represent
   those of the general public.

 5.5.3   Selected Site and Design Stage

 In  this stage, the surface disposal site is selected and
 detailed  site design  begins. Generally, the number of
 participants involved may drop off in this stage, but the
 level of activity may substantially increase. No matter
 how active the public has  been up to this point, nearby
 residents of the site  are not going to be happy with the
 siting decision. Participation efforts should increase on
 this particular group. Giving these people a role in site
 design will alleviate some hostility and, in the long-run,
 improve the public's  opinion of the proposed operation.
 Appropriate activities in this stage are:

 •  Tours/field trips.  These are useful activities for spe-
    cial interest groups, such as residents near the se-
    lected surface disposal site, and the press. Before
  the proposed surface disposal site is designed and
  permitted, a tour of a comparable existing and opera-
  tional surface disposal site should be made. This can
  be far more effective than countless abstract discus-
  sions. After the proposed  surface disposal site  is
  opened, tours can be offered of this site to educa-
  tional and other groups. Arranging for aerial views of
  proposed and existing sites for small groups by char-
  tering a plane can be especially effective.
• Audiovisual presentations. These can be  quite
  useful at public information  meetings to reach people
  missed by the field trips. The effectiveness of this tool
  depends on the quality of the script and visuals, but
  audiovisual presentations can dispel much of the mis-
  information about surface  disposal that, may  result
  from past experience with improperly run sites.
• Task forces. The purpose  of these groups is to rec-
  ommend design  procedures in areas of particular
  concern for the public. This group could be a sub-
  group of the Advisory Committee  or  a committee
  made up of residents near the site. To be most effec-  .
  tive, the group should represent the various interest
  groups and have a technical orientation.
• Formal public hearings.  Although  at least one is
  usually  required  by law,  a public hearing is usually
  only a formality. Public hearings tend to be structured
  procedures involving prior  notification, placement of
  materials in depositories for citizen review prior to the
  hearing, and a formal hearing agenda. The hearing
  itself usually takes the form of a presentation by the
  consultants, followed by statements from the citizens
  in attendance. Questions are normally allowed, but
  argumentative discussion and "debates" are discour-
  aged because of time limitations. Sponsors tend to
  prefer to adopt a  "listening" posture and  allow the
  public to express itself without challenge.  This kind
  of detached attitude tends to generate a great deal
  of hostility in the  public. It conveys the message that
  the public  is powerless to  change engineering deci-
  sions and  this is precisely the type of message that
  a PPP is supposed to dissipate. Because public hear-
   ings are usually held late in the site development
   process after the design is already completed, they
   provide an insufficient means of legitimate citizen in-
  volvement in the complete planning, design, and op-
   eration decision-making process. The responsiveness
   of a public hearing can be enhanced by having elected
   officials chairing or at least  participating  in the process.
   Nevertheless, public hearings perform their proper legal
   and review functions only  as part of a total PPP.

 5.5.4  Construction and Operation Stage
 The role of  the public in this stage is limited, but  the
 actions of engineers and surface disposal site operators
 are extremely important. It is in this stage that the site
                                                     61

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 developers must "make good" on their assurances of
 running a well-operated,  well-maintained site.  Public
 confidence in local officials can be  reinforced through
 the proper handling of surface disposal  site develop-
 ment. Otherwise, it will be extremely difficult to establish
 public support for this or any future surface  disposal
 project Public participation must continue throughout
 the project—if some minimum level is not maintained
 even the current project may fail.

 Public involvement during the construction and opera-
 tion stage most likely will consist mainly of complaints
 related to construction and operation activities. Mecha-
 nisms to handle this interaction include:

 • Telephone line. This is a good tool to  register com-
   plaints and concerns and to answer questions. It is im-
   portant that each call be followed up with a response
   addressing the actions taken to alleviate  the problem.

 • Ombudsman or representative.  This  is an individ-
   ual  who has the ear of the  site operators and can
,   mediate any difficulties that citizens feel are not being
   adequately handled.

 5.6   Timing of Public Participation
       Activities

 A public participation program should  begin very early in
 the development of a proposed project and continue
 throughout the project. All persons concerned should
 have the opportunity to express their views before any
 decisions affecting the general public are made  and
 should be kept informed and  involved throughout the
 course of the project.

 To be  effective, program activities must be diversified
 and sustained. Correct timing is critical. Table 5-3 lists
 suggested timing  of PPP activities for a sample surface
 disposal site project. Public hearings are formalities and,
 as such, may occur only at the beginning and end of the
 planning process. Advisory Committee meetings have
the function of providing a forum for progress reports
and regular input and, therefore, are scheduled to occur
from every 2  to 3 months. Public meetings are  held
jointly with Advisory Committee meetings and are timed
to obtain input during the critical points in decision-mak-
ing. Sufficient time is allowed after each public meeting
to give decision-makers time to react  to comments and
incorporate suggestions before final determinations are
made.  The various other informational/educational ac-
tivities  are scheduled around the public and Advisory
Committee meetings to arouse public interest at times
when input will be the most valuable.

5.7   Potential Areas of Public Concern

A PPP should dispel any myths and misinformation
the public may have concerning surface disposal—for
 example, the widely held perception that sludge is al-
 ways malodorous, highly contaminated, and otherwise
 repulsive. A PPP also should address the impacts of all
 surface disposal developments and other issues of con-
 cern in an environmental impact report, if one has been
 prepared. The most effective participation activities for
 handling these issues  are  the interaction techniques
 (i.e., public meetings, tours/field trips, and displays that
 are manned by personnel to answer questions). Some
 of the concerns most likely to arise during surface dis-
 posal development are:

 • Loss of prior land use

 • Land planning and zoning problems

 • Ground-water pollution and  leachate

 • Methane  gas migration

 • Vector attraction

 • Noise

 • Odor

 • Aesthetics,  including site visibility

 • Safety and  health

 • Traffic

 • Spillage

 • Sedimentation and erosion

 • Completed site and final land use

 Local officials should be prepared to handle questions
 concerning these issues. Obviously most of these prob-
 lems simply do not arise with a well-operated, efficiently
 run site, and this fact should be heavily emphasized.
 Also, because each situation is  unique, mechanisms to
 ease these concerns have to be tailored to the charac-
 teristics of each site. Local residents and officials should
 be creative  in solving any problems that may arise.
 Above all, the attitude of local  officials  during interac-
 tions with citizens is extremely important and must at all
 times be open and responsive.

 5.8    Conclusion

 Even the best program to involve the public in surface
 disposal site decision-making may not alleviate citizen
 dissatisfaction or anger. This criticism has often been
 cited to justify only minimal public participation efforts.
 However, active public involvement will  positively con-
tribute to the long-term political and public acceptability
of any plan, increase public confidence in local officials,
and give citizens a real  opportunity to take part  in the
land management decisions of their community. A PPP
is an essential part of any surface disposal  program.
                                                   62

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Table 5-3.  Suggested Timing of Public Participation Activities for Sample 30-Month Landfill Project
PPP activities and mechanisms
Publ ic hearings
Publ Ic meetings
Advisory Committee meetings
HalHng list development and
mall Ings
Availability of contact people
Newspaper articles
New releases
kudfo-vlsual presentations
Newspaper advertisements
'osters, brochures, and
displays
Workshops
Radio talk-shows
Tours/field trips
Ombudsman
Task force
Telephone line
Decision stage
Initial
planning
Site selection
Design
Con- I
structlonj Operation
Month
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               joint meeting
 5.9   References
 1. Canter, L. 1977. Environmental impact assessment. New York, NY:
   McGraw-Hill, pp. 221-222.
2. CH2M Hill,,Donahue and Associates, etal. 1977. Preliminary draft:
  Community involvement program, metropolitan sewerage district
  of the county of Milwaukee, water pollution abatement program
  (December), pp. A-1 to A-8.
3. U.S. EPA. 1988. Seven cardinal rules of risk communication. OPA-
  87-020. Washington, DC.
                                                            63

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                                              Chapter 6
                                       Field Investigations
6.1   Purpose and Scope

This chapter summarizes the regulatory requirements
that might  require site-specific field investigations  for
selecting a site for surface disposal of sludge, and it
provides an overview of methods and approaches to
planning for field investigations. Because the extent of
field investigations for a particular site will depend on the
size and complexity  of surface and subsurface condi-
tions, this  chapter emphasizes relatively  simple and
inexpensive field techniques that in  many instances
might be adequate for sludge surface disposal sites for
small and  medium-sized  communities (i.e.,  tens of
acres). Small-scale sites with complex subsurface con-
ditions and sites for surface disposal of sewage sludge
produced by large cities (i.e.,  hundreds of acres) will
require  use of more  sophisticated and expensive field
equipment  and methods. This chapter also identifies
reference sources where more detailed information on
such methods can be found.

6.2  Regulatory Requirements

6.2.1   Part 503 Regulation

Section 4.2.1 (Site Selection Regulatory Requirements)
describes in more detail the Part 503 requirements con-
cerning field investigations and  the siting of  sewage
sludge surface disposal sites. If the site selection proc-
ess described in Chapter 4 identifies one or more poten-
tially suitable  sites for which  Part  503 locational
restrictions might apply, one or more of the following
types of field investigations might be required:

• A determination about the presence of any threat-
   ened or  endangered species or a critical habitat.

• Hydrologic engineering studies to determine whether
   active sewage sludge units  can be designed so as
   not to restrict  flow of a 100-year flood, where  the
   proposed active sewage sludge unit is located within
   the boundaries of  a  100-year floodplain.

• Geologic, geophysical, and  soil engineering investi-
   gations where the active sewage sludge unit is lo-
   cated within a seismic impact zone or in the vicinity of
   one or more active faults (i.e., movement  has occurred
  within the last 11,000 years or so), or the area com-
  prises geologically unstable materials.

• Geologic and geotechnical investigations (generally
  required  when  the active sewage sludge unit will
  have a liner and leachate collection system).

• Soil and  hydrologic investigations, if  known or sus-.
  pected wetlands are located within the proposed sur-
  face disposal site.

6.2.2  Part 258 Regulations

A complete discussion of the regulatory requirements
under Part 258 concerning field investigations and siting
of MSW landfills is beyond the scope of this manual. See
U.S. EPA (1993d) for detailed information on the Part
258 regulation.

6.2.3   Other Regulatory Requirements and
       Programs

Special  or more focused field investigations also might
be required if use of the site for sewage sludge disposal
is restricted by other regulatory requirements  of pro-
grams at the federal, state, or local level. Examples of
siting issues covered by other federal statutes or regu-
latory programs include:

• Presence of sites  of archaeological or historical signifi-
  cance. Significant archaeological sites are often located
  within floodplains or on terraces along major rivers.

• Areas protected under the EPA-approved state well-
  head protection programs or under EPA's sole source
  aquifer program.

• Areas  located over aquifers with a Class I or Class II
  designation.

Any state environmental protection statutes and regula-
tions not originating at the federal level that might affect
siting of sewage sludge surface disposal sites should be
identified during the site selection process and appropri-
ate field investigations should be undertaken. Similarly,
any local zoning ordinances or restrictions should be
identified in the site selection phase, and field investiga-
tions should be designed to obtain any information required
                                                   65

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 to demonstrate compliance or justify the  granting of
 variances.

 6.3   Collection of General Site
       Information

 Collection and review of available information about a
 site and the surrounding area should be the starting
 point for any field investigation. If multiple potential sites
 have been evaluated during the site selection process
 (Chapter  4) then much of the more  general types of
 information for the area (i.e., soil, geologic, and hydro-
 logic maps  and reports) will have already  been gath-
 ered. Such maps are useful  for providing a general
 understanding of the geologic and hydrologic setting for
 a particular site, but generally will not provide specific
 information about the site itself. Table 6-1 identifies gen-
 eral sources for identifying and reviewing existing infor-
 mation. Makower (1992) is a useful general reference
 on types and sources of maps. This section discusses how
 to obtain more specific types of information: (1) topog-
 raphy and aerial photographs (Section 6.3.1); (2) soils,
 geologic,  and related information (Section  6.3.2); and
 (3) hydrologic and related information  (Section 6.3.3).

 Major types of commonly available information that1 can
 provide useful  information for sites  involving tens or
 hundreds  of acres include: (1) topographic maps (scale
 1:24,000), (2) aerial photographs (scale 1:15,000 to
 1:20,000  are  best), (3)  published  Soil Conservation
 Service (SOS) soil survey maps (which usually range in
 scale from around 1:15,000 to 1:20,000), (4) water well
 drill  logs,  and  (5)  Federal  Emergency Management
 Agency (FEMA) floodplain maps. Speaking with knowl-
 edgeable  individuals in  local  government  utility and
 planning  agencies,  state  natural resource/environ-
 mental agencies, and district offices of the  SCS, U.S.
 Army Corps of Engineers, U.S.  Geological Survey
 (USGS), and U.S. Fish and Wildlife Service  is probably
 the best way to identify existing published and unpub-
 lished maps and reports with detailed information about
the site or nearby areas. Interviews with local, long-time
 residents  also are an important source of information
about the  use-history of a site.

 In most instances the most important available informa-
tion relevant to a site can be identified  after 2 or 3 days
spent contacting  agencies on the telephone. It also
might be necessary to spend some time in one or more
libraries (Table  6-1) reviewing  documents that are no
longer in  print. For large projects, on-line computer
searches  can save significant time  and  money  by
quickly retrieving article citations on a given subject and
eliminating manual searches of annual  or  cumulative
indexes. A search is performed using key words, author
names, or title words, and can be delimited by ranges
of dates or a given number of the most recent or dated
references. A search typically requires about  15 minutes
 online and  costs $50 to $100 for computer time and
 off-line printing of citations and abstracts. Doctoral dis-
 sertations  and masters  theses are another possible
 source of information about an area. Table 6-1 provides
 information on how to identify possibly relevant disser-
 tations and theses, and how to obtain them.

 6.3.1  Topography and Aerial Photographs

 Table 6-2 identifies sources for topographic maps. Topo-
 graphic maps (at a scale of 1:24,000) published by the
 USGS are available for most areas of the United States
 and are available in electronic format from several sources
 (Table 6-2). The resolution of these maps (which generally
 have contour intervals of 10 ft or more) are usually not
 adequate for detailed site engineering and design pur-
 poses (see  Section 6.4.1), but are useful for identifying
 significant site surface characteristics during initial field
 investigations. The simplest method for identifying the
 availability and titles of topographic maps is to refer to
 a current state index  map, which  shows all currently
 available topographic maps. If a potential site is located
 near a city, more detailed topographic maps  may be
 available from city planning or utility departments.

 The first place to check for available aerial photographs
 is the nearest district offices of the SCS and the Agricul-
 tural Stabilization and Conservation Service. These of-
 fices, usually located in the same building and serving
 one or more counties, should have on file all aerial
 photographs taken for the U.S. Department of  Agricul-
 ture throughout the county; these will typically range in
 scale from 1:15,000 to 1:24,000 (1 in. = 1,250 ft to 1 in.
 = 2,000 ft). In parts of the United  States, the earliest
 aerial photographs date back to the 1930s. Examination
 of the full time-series of aerial photographs for a site is
 an excellent way to learn about changes in vegetation
 and land use that have taken  place. Fracture trace and
 lineament analysis using aerial photographs is a useful
 way to identify possible preferential paths of contami-
 nant transport.  Again,  all available aerial photographs
 should be viewed stereoscopically to identify fracture
 traces and other lineaments, because  the same line-
 aments might not be visible on all photographs due to
 differences in vegetation  or atmospheric conditions at
the time the photograph was taken.

 For site-specific investigations, aerial photographs with
 a  scale larger than 1:40,000  have a relatively limited
 usefulness;  however, larger-scale photographs (up to
 1:120,000),  including satellite remote sensing imagery
 might be useful for placing a site in its broader environ-
 mental context. Table 6-3 identifies sources for larger-
scale aerial photographs  and satellite remote sensing
 imagery. Landsat satellite sensors record images in four
spectral bands: Band 4 emphasizes sediment-laden and
shallow waters; Band 5 emphasizes  cultural features;
Band 6 emphasizes vegetation, land/water boundaries,
                                                   66

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Table 6-1.  General Information Sources (U.S. EPA, 1993e; Sara, 1994)

Source                         Type(s) of Information                Comments
Federal agencies


State, regional, and local
agencies
Knowledgeable individuals
 State and federal projects
 AGI Directory of Geoscience .
 Departments

 National Technical Information
 Service, 5228 Port Royal Rd.,
 Springfield, VA 22161;
 800/553-6847

 Libraries

 Government Agency
 Academic Institutions
 Local public libraries
All types of information (see
subsequent tables).

Soils, land use, flood plains,Aground
water, aerial photographs, well
records, geophysical borehole logs.
Historic information, past site owners
and practices. Published and
unpublished reports and maps.
 Site specific assessment data for
 dams, harbors, river basin
 impoundments, and federal highways.
 Faculty members.

 Government and other technical
 publications that are out of print or
 for which limited copies were printed.
 All types.
 All types.
 Physical and historical characteristics
 of the surrounding area.
 Computerized Online Databases

 DIALOG subscriptions and
 information: 800/3-DIALOG
 Master Directory (MD), User
 Support Office, Hughes STX
 Corp., 7601 OraGlen Dr., Suite
 300, Greenbelt, MD 20771;
 301/513-1687
  Earth Science Data Directory
  (ESDD), U.S. Geological
  Survey, 801 National Center,
  Reston, VA 22092;
  703/648-7112
 Accesses over 425 data bases from
 a broad scope of disciplines
 including such databases as
 GEOREF and GEOARCHIVE.

 The MD is a multidisciplinary
 database that covers earth science
 (geology, oceanography, atmospheric
 science) and space sciences.
  ESDD is a database that contains
  information related to geologic,
  hydrologic, cartographic, and
  biological sciences.
See subsequent tables.


Local county, town, and city planning boards commonly
provide data on general physical characteristics of areas within
their jurisdiction. Most states have environmental protection
and natural resource agencies (geology, water, agriculture,
etc.) that have information related to geology, remote sensing,
and water.

Time can be saved in the initial stages of a data search by
contacting knowledgeable individuals personally or by
telephone for references and an overview of an area, as well
as for specific problems and details that may be unpublished.
People to contact include: federal agency personnel (USGS,
SCS, Army Corps of Engineers, Fish and Wildlife Service);
state environmental protection, geological and water survey
personnel; local well drillers, consulting engineers, architects,
and  residents.

Project reports  contain data on soil, hydrologic, geologic and
geotechnical characteristics as well as analysis, construction
drawings and references. Most are easily obtained by
contacting the responsible agency. Surface water and
geological foundation conditions such as fracture orientation,
permeability, faulting, rippabillty, and weathered profiles are
particularly well covered in these investigations.

Regular updates of faculty, specialties, and telephone numbers.


Documents can be obtained as hard copy of microfiche.
 Excellent library facilities are available at the U.S. Geological
 Survey offices in Reston, VA; Denver, CO; and Menlo Park,
 CA. U.S. EPA has excellent libraries in Washington, its 10
 Regional Offices, and environmental research laboratories
 (Cincinnati, OH; Athens, GA; Ada, OK; Las Vegas, NV). State
 environmental and natural resource agencies often have
 libraries addressing the Agency's main focus.

 The amount of environmental information that can be obtained
 from academic institutions varies with the size. Larger
 universities often have separate geology libraries and serve as
 repositories for federal documents.

 Especially good sources for local maps and history. Almost any
 other document can also be obtained through interlibrary loan.
 Provides indexes to book reviews and biographies; directories
 of companies, people, and associations; and access to the
 complete text of articles from many newspapers, journals and
 other sources.

 MD is a free online data information sen/ice for data generated
 by NASA, NOAA, USGS, DOE, EPA, and other agencies and
 universities as well as international data bases. Includes
 personal contact information, access procedures to other
 databases. Contact MD User Support Office for information on
 access via span nodes, Internet, or direct dial.

 Also included are databases that reference geographic,
 sociologic, economic, and demographic information.
 Information comes from NOAA, NSF, NASA; EPA and
 worldwide data sources.
                                                                67

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 Table 6-1.   General Information Sources (U.S. EPA, 1993e; Sara, 1994} (continued)

 Source                         Type(s) of Information                Comments
 Dissertations and Theses

 Comprehensive Dissertation
 Index (GDI)
 DATRIX II, University
 Microfilms International,
 300 N. Zeeb Rd.,
 Ann Arbor, Ml 48106;
 800/521-3042,
 313/761-4700 (In Alaska,
 Hawaii, and Michigan)

 United States Geology: A
 Dissertation Bibliography by
 Stata
 Dissertation Abstracts
 International, Volume B -
 Science and Engineering and
 Masters Abstracts
 PhD doctoral dissertations.
 PhD dissertations and masters
 theses.
 PhD dissertations and masters
 theses.
 Extended abstracts of PhD
 dissertations from more than 400
 U.S. and Canadian universities;
 150-word abstracts of masters theses.
 Citations began in 1861 and include all doctoral dissertations
 from U.S. universities and most accepted in North America
 thereafter. The index is available at larger library reference
 desks and is organized in 32 subject volumes and 5 author
 volumes. Specific titles are located through title keywords or
 author names.

 Using title keywords, a bibliography of relevant theses can be
 compiled and mailed to the user within one week. In addition,
 the DATRIX Alert system can automatically provide new
 bibliographic citations as they become available.
 Free index from University Microfilms International (UMI).
 However, this index does not include dissertations from some
 universities that do not make submissions to UMI for
 reproduction or abstracting. DATRIX II or Comprehensive
 Dissertation Index must be used to locate such citations.

 Monthly publication of UMI. Abstracts of potentially useful titles
 obtained from GDI or DATRIX II can be scanned to determine
 whether it is  relevant to the project at hand. Both Dissertation
 Abstracts International and Masters Abstracts are available at
 many university libraries. A hard (paper) or microfilm/fiche copy
 on any abstracted dissertation can be purchased from UMI.
 Non-indexed or abstracted dissertations or theses must be
 obtained from the author or the  university where the research
 was completed.
Tablo 6-2.  Topographic Data Sources (U.S. EPA, 1993c; Sara, 1994)

Source                         TVpe(s) of Information
                                      Comments
 Branch of Distribution, USGS
 Map Sales, Box 25286.
 Federal Center, Denver, CO
 80225; 303/236-7477.
Geographic Names
Information System (GNIS),
USGS. 523 National Center,
Reston, VA 22092;
703/648-4544
Geographic Information
Retrieval and Analysis System
(GIRAS), USGS. Earth
Science Information Center
(ESIC), 507 National Center,
Reston, VA 22092;
800/USA-MAPS

U.S. Geodata Tapes,
Department of the Interior,
Room 2650, 18th & C Sts.,
NW, Washington, DC 20240;
202/208-4047
 Index and quadrangle maps for the
 eastern U.S. and for states west of
 the Mississippi River including Alaska
 and Hawaii.
Topographic Names Database:
descriptive information and official
names for about 55,000 topographic
maps, including out-of-print maps.
Topographic Maps Users Service:
organized and summarized
information about cultural or physical
geographic entities.

Land use maps, land cover maps,
and associated overlays for the
United States.
These computer tapes contain
cartographic data available in two
forms: (1) graphic to generate
computer plotted maps; (2)
topologically structured for input into
geographic information systems.
A map should be ordered by name, series, and state. The
same quadrangle name may be used 'at several scales so it is
especially important that the series scale be specified: 7.5
minute (1:24,000),  15 minute (1:62,500), or two-degree
(1:250,000). Other scales may be available for particular areas.

GNIS provides a rapid means of organizing and summarizing
current information about cultural or physical geographic name
entities. The database contains a separate file for each state,
the District of Columbia, and territories containing all 7.5 min.
maps published or planned. Printouts and searches are
available on a cost recovery basis.
Map data are available in both graphic and digital form, and
statistics derived from the data are also available. Searches for
either locations or attributes can be made.
Tapes are available for the entire U.S., including Alaska and
Hawaii, and are sold in 4 thematic layers: boundaries,
transportation, hydrography, and U.S. Public Land Survey
System. Each can be purchased individually. Tapes can be
ordered through the Earth Science Information Center
(ESIC—see above) or through the following ESIC offices:
Anchorage, AK (907/786-7011); Denver, CO (303/236-7477);
Menlo Park, CA (415/329-4309); Reston, VA (703/860-6045);
Rolla, MO (314/341-0851); Salt Lake City, UT (801/524-5652);
Spokane, WA (509/456-2524); and Stennis Space Center, MS
(601/688-3541).
                                                              68

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Table 6-2.  Topographic Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)

Source                        Type(s) of Information                 Comments
Topographic Database,
National Geophysical Data
Center, NOAA, Code E/GC1,
325 Broadway,
Boulder, CO 80303;
303/497-6764

State geological surveys
Commercial map supply
houses
                               This system contains a variety of
                               topography and terrain data sets
                               available for use in geoscience
                               applications.
                                Topographic maps.


                                Topographic and geologic maps.
The data were obtained from U.S. Government agencies,
academic institutions, and private industries. Data coverage is
regional to worldwide; data collection methods encompass
map digitization to satellite remote sensing.
Many state geological surveys sell USGS topographic maps
for the state in which they are located.

Commercial map supply houses often have full state
topographic inventories that may be out of print through
national distribution centers. Digitized topographic maps can
also be obtained from some suppliers.
Table 6-3.  Aerial Photography and Remote Sensing Sources (U.S. EPA, 1993c; Sara, 1994)

Source                         Type(s) of Information                Comments
                                Conventional aerial photography
                                scales of 1:15,000 to 1:40,000.
 Aerial Photography Field
 Office, U.S. Department of
 Agriculture, P.O. Box 30010,
 Salt Lake City, UT 84130;
 801/975-3503

" District ASCS and SCS offices    Aerial photography.
 Earth Resources Observation
 System (EROS) Data Center,
 USGS, Sioux Falls, SD 57198;
 605/594-6151
 NASA Aerial Photography
 Photogrammetry Division,
 NOAA, 6001 Executive Blvd.,
 Rockville, MD 20852;
 301/443-8601

 Aerial Photo Section, Bureau
 of Land Management,
 P.O. Box 25047,
 Bldg. 46, Federal Center,
 Denver, CO 80225;
 303/236-7991

 Cartographic and
 Architectural Branch,
 National Archives,
 8 Pennsylvania Ave. NW,
 Washington, DC 20408;
 703/756-6700

 Commercial Aerial
 Photography Firms
                                Aerial photography (scales 1:20,000
                                to 1:60,OQO) obtained by USGS and
                                federal agencies other than SCS is
                                available as 230 mm by 230 mm
                                prints. Landsat satellite multispectral
                                imagery can also be obtained from
                                the EROS Data Center.
                                Aerial photography available in a
                                wide variety of formats (black and
                                white, color, color infrared). Scales
                                generally range from 1:60,000 to
                                1:120,000.

                                Color and black-and-white aerial
                                photographs at scales ranging from
                                1:20,000 to 1:60,000.
                                 BLM has aerial photographic
                                 coverage of over 50 percent of its
                                 land in 11 western states.
                                 Airphoto coverage from the late
                                 1930s to the 1940s can be obtained
                                 for portions of the U.S.
                                 Existing air photos flown for other
                                 clients, or new photography for site
                                 of interest.
Aerial photographs by the various agencies of the U.S.
Department of Agriculture: Agricultural Stabilization and
Conservation Service (ASCS), Soil Conservation Service
(SCS), and Forest Service (USFS) cover much of the U.S.


District offices of the USDA Agricultural Stabilization and
Conservation Service and the Soil Conservation Service are
usually the best starting point for identifying available aerial
photography at the county level.

Because of the large number of individual photographs needed
to show a region, photomosaic indexes are used to identify
photographic coverage of a specific area. The EROS Data
Center has more than 50,000 such mosaics. Mosaics and
aerial photographs are also available from the USGS Map
Sales office in Denver (Table 6-2). The Data Center can
provide a computer listing of all imagery on file for (1) point
search (longitude and latitude), (2) area quadrilateral (four
lat/long coordinates), and (3) map specification (point or area).

Coverage restricted to areas selected for testing of
remote-sensing instruments and techniques. Available from
 EROS Data Center (see above).
 The Coastal Mapping Division of the National Oceanic and
 Atmospheric Administration (NOAA) maintains coverage of the
 tidal zone of the Atlantic, Gulf and Pacific Coasts. An index
 can be obtained from the Coastal Mapping Division.
 This service may be useful for early documentation of site
 activities. Early airphotos may also be on file in ASCS and
 SCS District offices (see above). Foreign airphoto coverage for
 the World War II period is also available.
 Many firms can also develop detailed topographic site maps
 using photogrammetric techniques. For a listing of nearby firms
 specializing in these services consult the yellow pages or
 contact: American Society of Photogrammetry and Remote
 Sensing, 5410 Grosvenor Lane, Suite 210, Bethesda, MD
 20814; 301/493-0290.
                                                               69

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 and landforms; and Band 7 is similar to Band 6 except
 that it provides better penetration through haze. Band 5
 gives the best general-purpose view of the earth's surface.

 6.3.2   Soils, Geologic, Geophysical, and
          Geotechnical Information

 Table  6-4 identifies sources of information on soils, ge-
 ology,  geophysical  and  geotechnical  information.  If
 available, a county soil  survey published by the SCS is
 one of the single best sources of .information about a site
 because it also provides an indication of subsurface
 geologic conditions and contains a wealth of information
 on typical soil physical and chemical characteristics
 (Table 6-5). If a soil survey is not available,  check to see
 if the site is located within a farm property listed with the
 local Soil  and Water Conservation District. If so, there
                                 may be an unpublished farm survey on file in the District
                                 SCS office. As with published topographic maps gener-
                                 ally,  the scale  of an  SCS  soil survey is usually  not
                                 adequate for site engineering  and  design  purposes;
                                 thus,  part of a  field investigation  should include  more
                                 detailed mapping of soils, if possible (see Section 6.4.2).
                                 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. Table 6-5  summarizes the kind of information that
                                 can be found on these sheets. Estimated soil properties
                                 are typically given as ranges or values for different soil
                                 horizons, and direct field observation and sampling is
                                 required for more accurate definition of soil properties.
                                 Even if a published soil survey is available, these sheets
                                 provide a convenient reference for characteristics of soil
                                 series occurring within a site. The same information on
 Table 6-4.  Soils, Geologic, Geophysical, and Geotechnical Data Sources (U.S. EPA, 1993c; Sara, 1994)

 Source                       TVpe(s) of Information                   Comments
 USDA Soil Conservation
 Service; 202/720-1820
 U.S. Geological Survey
 (USGS) Bocks and Open File
 Reports Sales, Federal Center,
 Box 25425, Denver, CO
 80225; 303/236-7476

 USGS Main Library, 950
 National Center, Reston, VA
 22092; 703/648-4302
 Geologic Names of the United
 States (GEONAMES),
 Geologic Division, USGS, 907
 National Center, Reston, VA
 22092
 County-level soil surveys are available
 for about 75% of the country. Soil series
 descriptions and interpretation sheets
 contain information on soil physical and
 chemical properties.

 USGS produces annually numerous
 publications including maps, bulletins,
 circulars, professional papers and
 open-file reports.


 The Reston library contains more than
 800,000 books, monographs, serials,
 maps and microforms covering all
 aspects  of earth and environmental
 sciences.
GEONAMES is an annotated index of
the formal nomenclature of geologic
units of the U.S. Data includes
distribution, geologic age; USGS usage,
lithology, thickness, type locality and
references.
Geologic Indexes and Databases

A Guide to Information
Sources In Mining, Minerals,
and Geosciences (Kaplan,
1965)
Information on more than 1,000
governmental and nongovernmental
organizations in 142 countries.
A Subject and Regional
Bibliography of Publications
and Maps in the Geological
Sciences (Ward, 1972)
Bibliographies of geologic information for
each state in the U.S. and reference for
general maps and ground-water
information for many sites.
Bibliography and Index of Geology
American Geological Institute
(AGI)
Includes worldwide references with
listing by authors and subject. Published
monthly with annual cumulative index.
 District offices covering one, or several counties may
 contain unpublished soil mapping. Published soil surveys
 and soil series description and interpretation sheets can be
 obtained from SCS state offices, located in each state
 capital.

 USGS Circular 900, Guide to Obtaining USGS Information
 (Dodd et al., 1989) is available at no cost.
 USGS has one of the largest earth science libraries in the
 world. Library staff and users can access the online catalog
 from terminals at the Reston library and from the regional
 libraries located in Denver, CO; Flagstaff, AZ; and Menlo
 Park, CA. The database can be searched by author, title,
 key words, subjects, call numbers, and corporate/
 conference names.

 Printouts are not available. Diskettes containing data for
 two or more adjacent from USGS books  and reports sales
 (address above). Magnetic tapes can be obtained from
 NTIS (Table 6-1).
An older, useful guide. Part II lists more than 600
worldwide publications and periodicals including indexing
and abstracting services, bibliographies, dictionaries,
handbooks, journals, source directories, and yearbooks in
most fields of geosciences.

Provides a useful starting place for many site assessments.
A general section outlines various bibliographies and
abstracting services, indexes and catalogs, and other
sources of geologic references.
Replaces separate indexes published by the USGS (North
American references only) and the Geological Society of
America/GSA (references exclusive of North America) until
1969. Both publications merged in 1970 and were
published by GSA through 1978, when AGI continued its
publication.
                                                         70

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Table 6-4.  Soils, Geologic, Geophysical, and Geotechnical Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)

Source                       Type(s) of Information                  Comments	    '
GEOREF

American Geological Institute
GEODEX Retrieval System
with Matching Geotechnical
Abstracts

GEODEX International, Inc.,
P.O. Box 279, Sonoma, CA
95476
KWIC (Keyword-in-Cpntents)
Index pf Rock Mechanics
Literature

Geophysical Data

U.S. Geological Survey, Box
25046, Federal Center,
Denver, CO 80225
 National Geophysical Data
 Center (NGDC), NOAA, Mail
 Code E/GC, 325 Broadway,
 Boulder, CO 80303; Land
 data: 303/497-6123; Seismic
 data: 303/497-6472
 Electric Well Log Services,
 P.O. Box 3150, Midland, TX
•79702; 915/682-7773

 Geophysical Survey Firms
Computer database with bibliographic
citations from 1961 to present.
Computer database with engineering
geological and geotechnical references.
Engineering geologic and geotechnical
references.
Aeromagnetic maps, magnetic
declination, landslide information,
earthquake data. Many USGS
publications contain geophysical survey
for specific areas.
 NGDC maintains a computer database
 on earthquake occurrence from
 prehistoric times to the present. NGDC
 also maintains databases on other
 parameter, such as topography,
 magnetics, gravity, and other topics.
 Electric logs for many petroleum wells
 can be obtained from one Of several well
 log libraries in the U.S.

 Surface and borehole geophysical
 surveys.
Available through online services or on CD ROM. Includes
references contained in the Bibliography and Index of
Geology. Available at many university libraries.
The GEODEX is a hierarchically organized system
providing easy access to the geotechnical literature. Can
be purchased on a subscription basis, or available at many
university libraries.

Published as two volumes (Grawlewska, 1969; Jenkins and
Brown, 1979), and can be found in many earth science
libraries.
Aeromagnetic maps (1:24,000): Branch of Geophysics, MS
964; 303/236-1343. Earthquake data: National Earthquake
Information Center (NEIC), MS 967; 303/236-1500 (recent
earthquakes only). Landslide data: Landslide Information
Center, MS 966; 303/236-1599. Magnetic Declination
Information: Branch of Global Seismology and
Geomagnetism, MS 967; 303/236-1369. GEOMAG
contains current and historical magnetic-declination
information. Current or historical values back to 1945 can
be obtained by calling 800/358-2663. The entire GEOMAG
database can also be  accessed via modem.

NGDC is a central source for dissemination of earthquake
data and information for both technical and general users,
except for recent earthquakes (see USGS  above). For a
fee, a search can be made for one or more of the following
parameters: (1) geographic area (circular or rectangular
area), (2) time period  (starting 1638 for U.S.), (3)
magnitude range, (4) date, (5) time, (6) depth, and (7)
intensity (modified Mercalli).

The geophysical logs  are indexed by survey section. To
obtain information on wells in a given area, a list of
townships, ranges, and section numbers must be compiled.

 Proprietary geophysical data can sometimes be obtained
from private survey firms if the original client authorizes
 release of the information. Even if the information cannot
 be released, firms may be willing to provide references to
 published information  they obtained before the survey, or
 information published  as a result of the survey.
 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.

 Existing site-specific subsurface  geologic  information
 typically will not be available  unless water wells or oil
 and gas exploration holes  are located  on or near the
 site. If water well or exploration boreholes are known or
 thought to exist at the site in nearby locations, available
 well/borehole logs should  be  obtained.  Water  well drill
 log files are typically maintained by state water resource
 agencies (Table 6-6), and state geological surveys or oil
 and gas agencies should be the first place contacted for
 information about other possible borehole logs.  Geo-
 physical survey firms and well log  libraries are other
                                 possible sources for subsurface borehole data (Table 6-4).
                                 If a site is  located near a numbered county,  state, or
                                 federal highway, the appropriate agency should be con-
                                 tacted to identify possible subsurface information  col-
                                 lected as part of road or highway construction projects.
                                 Table 6-4 identifies geologic indexes and databases for
                                 geologic and geotechnical literature, if a more extensive
                                 literature search should be appropriate for a site.

                                 Major areas of  holocene faulting can be  identified by
                                 consulting the series of maps that identify young faults
                                 (U.S. Geological Survey, 1978), which can be obtained
                                 from USGS Map Sales (Table 6-2). Figure  4-1  identifies
                                 major potential seismic impact zones  in the United
                                 States. If the site is located within or near any of the
                                                           71

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 Table 5-5.  Types of Data Available on SCS Soil Series
            Description and Interpretation Sheets
 Soil Series Description Sheet
 Taxonomte 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 Interpretations Sheet8
 Estimated Soil Properties (major horizons)
 Texture class (USDA, Unified, and AASHTO)
 Particle size distribution
 Liquid limit
 Plasticity Index
 Moist bulk density (g/cm3)
 Permeability (inJhr)
 Available water capacity (inJIn.)
 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)
                                   a Units indicated are those used by SCS.
                                   Note: Boldface entries are particularly useful for evaluating
                                   contaminant transport.
Table 6-6.  Hydrologic, Wetland, and Climatic Data Sources (U.S. EPA, 1993c; Sara, 1994)
Source                         Type(s) of Information                Comments
Hydrologic Information Unit,
USGS,
419 National Center,
Reston, VA 22092;
703/648-6817
Office of Water Data
Coordination (OWDC),
USGS, 417 National Center,
Reston, VA 22092;
703/648-5023
National Water Data Exchange
(NAWDEX), USGS, 421
National Center, Reston, VA
22092; 703/648-5677
Locations and phone numbers of
USGS Water Resource Division
District Offices; state water-resource
investigation summary reports.
Information on current federal water
data acquisition activities. Selected
publications are also available.
NAWDEX Master Water Data Index
and Water Data Source Directory
contain information on more than
460,000 water data sites and more
than 800 organizations that collect
water data respectively.
 Water Resources Investigations in [State, Year] are booklets
 describing projects and related publications by USGS and
 cooperating agencies. Summary folders by the same name
 show location of hydrologic-data stations and selected
 publications for the state. Also serves as reference office for
 Water-Resources Investigation reports released before 1982
 that were not issued as Open-File Reports (Table 6-4) or
 made available through NTIS (Table 6-1).
 Available publications include: (1) National Handbook of
 Recommended Methods for Wate'r-Data Acquisition, (2) Index
 to Water Data Activities in Coal Provinces in the U.S.  (5
 Volumes), and (3) Guidelines for Determining Flood Flow
 Frequency.
The NAWDEX Program Office and its 75 Assistance Centers
 (which includes all USGS Water Resources Division District
Offices)  help water-data users locate and obtain data,
 including bibliographic search in the WRSIC database (see
below). Fees for services depend on type of request and the
organization fulfilling the  request.
                                                             72

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Table 6-6.  Hydrologic, Wetland, and Climatic Data Sources (U.S. EPA, 1993c; Sara, 1994) (continued)

Source                        Type(s) of Information                 Comments
National Water Data Storage
and Retrieval System
(WATSTORE)


Water Resources Scientific
Information Center (WRSIC),
USGS, 425 National Center,
Reston, VA 22092;
703/648-6821

USGS Water Resources
Division District Offices
(WRD-DO)

USGS Hydrologic Publications
Federal Emergency
Management Agency,
Rood Map Distribution Center,
6930 (A-F) San Thomas Rd.,
Baltimore, MD 21227-6227;
800/358-9616

U.S. Army Corps of
Engineers (COE),
Washington, DC 20314-1000;
202/272-0660
 Fish and Wildlife Service,
 U.S. Department of the
 Interior,
 1849 C St. NW, Washington,
 DC 20240; 202/208-5634

 State Water Resource
 Agencies
 National Ground Water
 Information Center (NGWIC),
 National Ground Water
 Association,
 6375 Riverside Drive,
 Dublin, OH 43017;
 800/332-2104

 Climatic Data

 National Climatic Data Center
 (NCDC), Federal Building, 37
 Battery Park Ave., Asheville,
 NC 28801-2733; 704/259-0682
 Gale Research Company
 (1985)


 U.S. Department of Agriculture
All types of water data are accessed
through the WATSTORE computer
database.
Abstracts of water resources
publications throughout the world.
State-level water resources
investigation reports and data.


Various Series: Water-Supply Papers,
Water-Resource Investigation
Reports, Hydrologic Investigation
Atlases; State Hydrologic Unit Maps.

100-year floodplain maps are
available for most municipal areas at
a scale of 1:24,000. In some areas
more detailed FEMA Flood Insurance
Studies are available that delineate
500-year floodplain.

Location of navigable waters and
wetlands.
 National Wetland Inventory (NWI)
 maps.
 Well logs, state-collected hydrologic
 data.
 Computerized, on-line bibliographic
 database. Search by author,
 keyword, and date. Abstracts are
 relatively short and nontechnical.
 The National Oceanic and
 Atmospheric Administration's (NOAA)
 NCDC collects and catalogs nearly
 all U.S. weather records. Hatch
 (1988) provides a selective guide to
 climatic data sources.
 Climates of the States - NOAA
 Narrative Summaries, Tables, and
 Maps for Each State.

 County-level, local meteorological
 data.
NAWDEX (above) or USGS Water Resource Division District
Offices (see below) should be contacted for information on
availability of specific types.of data, acquisition of data or
products, and user charges.

Bibliographic information available through publications and
computerized bibliographic information services.  For additional
information contact Branch of Water Information  Transfer.
WRD-DOs serve as NAWDEX Assistance Centers, and can
provide up-to-date listings of water resource investigation
publications and  maps by USGS and cooperating agencies.

Publications available from USGS Book and Open File
Reports Section (Table 6-4); maps and atlases available from
USGS Map Distribution Section (Table 6-2).
Flood Insurance Rate maps and other flood maps can be
obtained from FEMA. These maps are also available from
USGS WRD-DOs and commonly from other agencies such as
the relevant city, town, or county planning office.
The COE has primary responsibility for regulation of wetlands.
Methods for delineating wetlands are contained in COE
(1987), and Federal Interagency Committee for Wetland
Delineation (1989). The nearest COE District office should be
contacted to identify available information.

The NWI has been completed largely using remote sensing
techniques and other available resource data.
 Hydrologic data can often be accessed through NAWDEX.
 Ground-water well logs commonly must be obtained from the
 appropriate state agency. Giefer and Todd (1972, 1976)
 identify water publications by State Agencies.

 Accessible to members and nonmembers through computer,
 modem, and telecommunications software. Photocopying
 service of most references and interlibrary loan service
 available.
 NCDC services include: (1) publications, reference manuals,
 and data report atlases, (2) data and map reproduction in
 various forms (paper copy, microfiche, magnetic tape,
 diskette), (3) analysis and preparation of statistical.summaries,
 (4) evaluation of data records for specific analytical
 requirements, (5) library search for bibliographic references,
 abstracts and documents, and (6) referral to organizations
 holding requested information.

 Provides general summary statistics and maps.
 Published SCS county soil surveys provide summary
 precipitation and temperature data. Agricultural Research
 Stations funded by the USDA Cooperative Extension Service
 often collect climatic data in areas where agricultural research
 is being done.
                                                              73

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 shaded areas on this figure, more detailed information
 about historic seismic activity in the area should be
 obtained. The National Oceanic and Atmospheric Admini-
 stration's National Geophysical Data Center (NGDC) in
 Boulder, Colorado, (Table 6-4) is the primary source of
 information for earthquake data. If there has been very
 recent seismic activity in the area, the USGS's National
 Earthquake Information Center (NEIC), in Denver, Colo-
 rado should be contacted (Table 6-4).

 General information  on geotechnical characteristics of
 near-surface soils at a site can be  obtained from soil
 survey information (USCS  classification of major soil
 horizons, liquid  limit, plasticity index, etc.—see Table
 6-5). Site-specific geotechnical information, however, is
 not likely to be available unless data from  highway
 adjacent or near the site exist (see discussion above).
 The availability of such information must be addressed
 during site-specific investigations (see Section 6.4.3).


 6.3.3  Hydrologic, Wetland, and Climatic
        Information

 Table 6-6 identifies  major  information  on hydrology,
 floodplains, wetlands, and climatic data.  In general, ex-
 isting hydrologic data fall into four primary categories:
 (1) stream discharge,  (2)  stream  water quality,  (3)
 ground-water levels,  and (4) ground-water quality. Typi-
 cally site-specific data will not be available, but relevant
 data from nearby or hydrogeologically similar monitoring
 points should be obtained. The state district offices  of
 the USGS's Water Resources Division,  which serve as
 local assistance centers  for  USGS's National Water
 Data Exchange (NAWDEX) is the best starting  point for
 identifying available hydrologic data that might be rele-
 vant  to a specific site. These offices are primarily  re-
 sponsible forfloodplain mapping, so they also should be
 asked about the availability of floodplain maps for the
 area of interest. Published floodplain maps also can be
 obtained from the FEMA's Flood Map Distribution Cen-
 ter (Table 6-6) and also might be available from city,
 town, or county planning  offices.

 If a National Wetland Inventory (NWI) map is not avail-
 able for the site being evaluated,  a published SCS soil
 survey will indicate the possible presence of wetlands.
 Soil series  located within  a site  should be  checked
 against the list of "hydric"  soil series  that has been
 developed by SCS (National Technical Committee for
 Hydric Soils, (1991). If wetlands are known or suspected
 to be present within  or near a site, more detailed site
 investigations will be required (see Section 6.4.5). An
 SCS  soil survey also  will indicate whether all or parts of
 a site are located within a floodplain, but more detailed
 investigations may be required to delineate the 100-year
floodplain if a  FEMA flood map is not available (see
Section 6.4.6).
 6.4   Site-Specific Data Collection

 The characteristics of a site as indicated by existing
 information about the site and its surrounding area will
 determine the type and extent of field investigations that
 will be required. As site geology and hydrogeology in-
 crease in complexity, more sophisticated and expensive
 site investigation techniques are required, as shown in
 Figure 6-1. The discussion in this section assumes that
 the ground-water system is relatively simple, consisting
 of a single unconfined aquifer in unconsolidated materi-
 als (Type I in Figure 6-1). Field investigation techniques
 for this type of site are relatively simple and inexpensive,
 requiring equipment ranging from handheld soil augers
 to power-driven equipment that is hand-portable or can
 be mounted on a pickup truck. Although a detailed dis-
 cussion of field methods for investigation of more com-
 plex sites is beyond the scope  of this handbook, Table
 6-7 identifies major recent references where information
 on such techniques can be found. Also, Section 6.4.6
 identifies major references that address methods for
 site-specific geotechnical investigations, and Appendix
 C identifies manufacturers and distributors of equipment
 for site-specific data collection.

 Table 6-7.  Guide to Major Recent References on
          Environmental Field Investigation Techniques8

 Reference        Description

 ASTM (1994)      Standard Guide to Site Characterization for
                 Environmental Purposes. Text and
                 appendices identify hundreds of ASTM
                 standard test methods for field and
                 laboratory methods. See also ASTM D420
                 (Standard Guide to Site Characterization for
                 Engineering, Design and Construction
                 Purposes).
 Nielsen (1991)     Practical Handbook of Ground-Water
                 Monitoring. Comprehensive handbook on
                 ground-water monitoring methods, which
                 also includes chapters on soil sampling and
                 vadose zone monitoring.
 Sara (1994)        Standard Handbook of Site Assessment for
                 Solid and Hazardous Waste Facilities.
                 Comprehensive handbook on solid and
                 hazardous waste  facility assessments.
 U.S. EPA (1987)     Technology Briefs: Data Requirements for
                 Selecting Remedial Action Technology.
                 Sections relevant to design of sewage
                 sludge surface disposal sites include:
                 grading, revegetation, diversion/collection
                 systems, and surface water/sediment
                 containment barriers. Summary tables for
                 each technique identify (1) data needs, (2)
                 purpose of the data, (3) collection methods,
                 and (4) costs.
U.S. EPA (1988a)    Guide to Technical Resources for the Design
                 of Land Disposal  Facilities. Most relevant
                 sections related to sewage sludge surface
                 disposal sites include sections on
                 foundations (useful if the potentially unstable
                 areas are present, and run-on/runoff
                 controls.
                                                     74

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Table 6-7.  Guide to Major Recent References on Environ-
           mental Field Investigation Techniques8 (continued)
Reference
Description
U.S. EPA (1991c)    Site Characterization for Subsurface
                    Remediation. Covers methods for
                    soil/geologic, ground-water and vadose-zone
                    hydrologic characterization and monitoring
                    techniques with a focus on applications for
                    remediation of contaminated sites. Chapters
                    2 through 9 cover techniques that are
                    applicable to any type of environmental field
                    investigation.

U.S. EPA (1993a)    Subsurface Field Characterization and
                    Monitoring Techniques. 2-volume document
                    providing summary information on more than
                    280 specific field investigation and
                    monitoring techniques. Volume I covers solid
                    and ground-water and Volume II covers the
                    vadose zone, chemical field screening and
                    analytical techniques. Appendix C contains a
                    comprehensive bibliography of major
                    references on subsurface characterization,
                    monitoring and analytical methods.
                                                                   Reference
Description
                                               U.S. EPA (1993b)    Solid Waste Disposal Facility Criteria:
                                                                   Technical Manual. Chapter 2 covers methods
                                                                   for identification and engineering design
                                                                   considerations related to floodplains,
                                                                   wetlands, fault areas, seismic impact zones
                                                                   and unstable areas. Chapter 5 covers
                                                                   ground-water monitoring well  design and
                                                                   construction and sampling.

                                               a See end of Section 6.4.6 for identification of major references for
                                               geotechnical characterization.
                                  Least Complex
                       CONCEPTOALHYpjROG|OLOGY.,,

                        SINGLE LAYER/HYDRAULIC CONDUCTIVITY
                                LAYEREDIMULTIPLE
                             HYDRAULIC CONDUCTIVITIES
                                Moderately Complex
                             LAYERED/MULTIPLE HYDRAULIC
                             CONDUCTIVITIES Ct GRADIENTS
                                   Highly Complex
                      V
                                                      Phase I Investigation
                                                      Phase II Investigation, Complete:
                                                         Stratigraphy/Lab Testing
                                                       • Piezometers
                                                       • Cross-sections
                                                       • Potentiometric Map
                                                       • Conceptual Model
                                                      Locate Monitoring Wells
                                                   Phase I Investigation
                                                   Phase II Investigation, Complete:
                                                      • Geophysics- Surface & Downhole
                                                      • Stratigraphy/Lab Testing
                                                      • Hydraulic Conductivities, LabXField
                                                      • Nested Piezometers
                                                      • Cross-sections/Stratigraphic Maps
                                                      • Potentiometric Map
                                                      • Flow net
                                                      • Conceptual Model
                                                      Locate Monitoring Wells
                                                    Phase I Investigation
                                                    Phase II Investigation, Complete:
                                                       • Geological Mapping
                                                       • Geophysics- Surface & Downhole
                                                       • Core Drilling/Angle Holes
                                                       • 3-D Geology/Lab Testing
                                                       • Infield Packer Tests/Lab Perms.
                                                       • Nested Piezometers
                                                       • Cross-sections & Stratigraphic Maps
                                                       • Potentiometric Surfaces
                                                       • Multiple Flow Nets
                                                       • Geochemistry of Ground-water
                                                       • Conceptual Models
                                                       Locate Monitoring Wejls
 Figure 6-1.   Site complexity indicators for selection of assessment techniques (Sara, 1994).
                                                                75

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 6.4.1  Site Land and Topographic Survey

 An accurate boundary survey and topographic base map
 are essential for developing a base map for plotting obser-
 vation points during field investigations and for design
 of pollution control measures such as terraces and sedi-
 ment ponds. Where a site comprises tens of acres, a scale
 of 1:1,200 (1 in. = 100 ft) or 1:2,400 (1 in. = 200 ft) with
 contour intervals ranging from 1 to 5 ft  will usually pro-
 vide the best base  map. Sites involving hundreds of
 acres may require larger scales (up to  1:6,000) to pre-
 vent base map size from becoming unmanageable. In
 very flat areas, contour intervals of 1 or 2 ft are required
 to accurately delineate subtle topographic variations. In
 steep areas, larger  contour intervals are appropriate.
 Topographic maps at scales of 1:2,400 or larger can be
 created using field surveys or photogrammetry from low-
 altitude  aerial photographs. Cost estimates from surveyors
 and commercial aerial photography/photogrammetry
 companies should be obtained. If the local yellow pages
 do not  list any photogrammetry  firms, the American
 Society  of Photogrammetry and Remote Sensing (ASPRS)
 might be able to provide the address and phone number
 of firms that work in the vicinity of  the site. Table  6-3
 includes ASPRS's address and phone number.

 6.4.2  Soil and Geologic Characterization
 Although  published soil surveys provide much useful
 information for preliminary site selection, they generally
 are not  adequate for site-specific design of sludge sur-
 face disposal sites. 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 iden-
 tify 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
 surface disposal of 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 expensive,  but
 will usually involve less delay. If  a private consultant
 conducts the soil survey, the person or persons actually
 carrying out the survey should be trained in soil mapping
 and classification methods used by SCS  for the National
 Cooperative Soil Survey.

 As discussed in Section 6.4.3 (Hydrogeologic Charac-
terization), where the permanent  or  seasonal high
water table is within 5 ft of the ground surface, crea-
tion of a water table map by a soil scientist based on
 observation of soil morphology can be a very cost-
effective way to obtain an initial characterization of a
site's hydrogeology.

Soil mapping  is  usually conducted using  handheld
augers  or tube probes  with subsurface observations
limited to  depths  of 5 ft or less.  Once  a detailed soil
 survey has been prepared, sites for deeper sampling
 can be selected to evaluate whether surface topography
 and soil types correlate with geologic  characteristics
 below the soil weathering zone (which generally extends
 to a depth of 5 ft or less), and for more detailed hydro-
 geologic and geotechnical characterization.

 Test pits are the best way to directly examine subsurface
 lithology and sedimentary features that affect the poten-
 tial for transport: of pollutants in the near surface be-
 cause  both  lateral  and vertical  variations can  be
 observed, and core samples allow direct observation of
 vertical changes in subsurface lithology and sedimen-
 tary features. Provided that gravel or other  rock frag-
 ments are absent, the most efficient and cost-effective
 way to collect deeper cores is usually by using truck-
 portable power-driven equipment. Such equipment can
 involve hand-held  electric, gasoline-powered, or com-
 pressor-operated vibrating hammers  for driving rods
 with probes affixed to the end (Figure 6-2a) and using a
 special jack to pull the probe to the surface (Figures 6-2b
 to 6-2d). Also, hydraulic probes can be mounted to a van
 or pickup truck (Figure 6-3) or on trailers or tractors.
 Probes driven with handheld power equipment typically
 yield cores of 1  in. in diameter. Mounted hydraulic probes
 can  provide cores of up to 2 in. Larger diameter cores
 are generally easier to describe because changes  in
 color, texture, and other features are more discernable.
 Boulding (1994) and U.S. EPA (1991 a) provide guidance
 on the description and  interpretation of subsurface cores.
 Where the subsurface contains large rock fragments, it
 may still be possible to  collect large-diameter cores (2
 inches) using larger drill rigs. Otherwise, drilling meth-
 ods that do not collect cores may have to be used. Also
 collection of core deep core samples (generally greater
 than 10 meters) generally requires use of drill rigs rather
 than hand-powered or truck-mounted equipment.

 Note: All deep boreholes represent channels for prefer-
 ential movement of leachate from sewage sludge and
 therefore should be filled with bentonite or an alternative
 suitable grout. Shallow boreholes within the sludge sur-
 face disposal site or that might receive  surface runoff
 from the site also should be plugged at the surface or
 grouted. Figure 6-4 illustrates a grouting  procedure us-
 ing a rigid pipe and flexible tremie tube. Where holes do
 not extend to the water table, plugging of  the upper part
 of the hole with soil material  may be adequate  as  a
 alternative to grouting.

 6.4.3  Hydrogeologic Characterization

 Hydrogeologic field investigations should focus on de-
veloping  a  three-dimensional  understanding  of  the
ground-water flow system so as to determine: (1) the
direction in which pollutants from sewage sludge would
travel if it entered an aquifer, (2) the speed with which
the pollutants would move, and (3) the best location for
                                                   76

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                                                       Chuck
                                                                     v Spool
                                                                             (b)
                                                                                             Lever handle

                                                                                             AT-99
                     (a)
                                                                                 (d)

Figure 6-2.  Core sampling with handheld power driver: (a) hammer driver (courtesy Solinst Canada); (b) positioning probe rod jack
           for manually retrieving deep core samples; (c) chuck in down position; (d) pulling position, level down (courtesy of
           Geoprobe Systems).
                                                         77

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                                                                            54'
                                                                                              48"
                                                                                                                    31"
                                                                                                                119'
                                                                                  54" stroke allows more room
                                                                                  for operation and longer probe rods.
Figure 6-3.  Hydraulic probes mounted in van and pickup truck (courtesy of Geoprobe Systems).
                                                                     Grout
                                   '/              '//////

                         (a) Installation            (b) Tube Removal               (c) Grouting

Rgura 6-4.  Narrow-diameter borehole grouting procedure using rigid pipe and internal flexible tremie tube.
                                                          78

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ground-water  monitoring  wells.   Generally,  hydro-
geologic characterization  should be  conducted by  a
qualified ground-water scientist, defined by EPA as

  an individual with a baccalaureate  or post-graduate
  degree in the  natural sciences or  engineering who
  has sufficient  training and experience in  ground-
  water hydrology and related fields,  as may be dem-
  onstrated   by  State   registration,   professional
  certification, or completion  of accredited  university
  programs, to make sound professional judgements
  regarding ground-water monitoring, pollutant fate and
  transport, and corrective action. 40  CFR 503.21 (I).1

This section focuses on relatively simple and inexpen-
sive techniques for characterizing the ground-water sys-
tem using:  (1) soil morphology where the seasonal high
water table is within 5 ft of  the ground surface; (2)
multiple piezometer installations to  develop  a three-di-
mensional  picture of hydraulic head  distribution; and (3)
flow net analysis to determine the direction  and speed
of ground-water  flow. For a Type I hydrogeologic setting
(Figure 6-1),  this  information can  be obtained using
handheld or portable power-driven equipment similar to
that described for soil and geologic characterization  in
Section 6.4.2. As noted above, references in Table 6-7
provide information on field investigation techniques for
more complex sites.

Depth to Water Table Based on Soil Morphology

Soil color serves as a good indicator  of soil-water con-
ditions, with grey colors of 2 chroma or less on a Munsell
Soil Color Chart typically indicating  a dominance  of
reducing conditions and bright colors indicating oxidiz-
ing conditions. In 1992 the SCS adopted an  extensively
revised and improved approach to describing and inter-
preting soils  that are  saturated during all  or part of the
year (Soil Survey Staff, 1992). The depth and pattern of
redoximorphic soil features allow estimation of the depth
of the permanent and seasonal high  water  table. Sea-
sonal perched water tables also can be identified based
on soil morphology, even if no water is perched at the
time of observation. Boulding (1994,  Appendix C) and
Vepraskas (1992) provide more detailed guidance  on
description and interpretation  of  soil redoximorphic
features.
Where the water table is within five feet of  the ground
surface (which is common in large areas of  the eastern
 United States) a detailed water table map  can be devel-
 1 The Part 503 rules do not explicitly state that hydrogeologic char-
 acterization be done by a qualified ground-water scientist, never-
 theless it wouild make sense to have such a person conduct or
 supervise this aspect of the field investigations. A qualified groud-
 water scientist fe required for developing a ground-water monitoring
 program or certify that placement of sewage sludge on an active
 sewage sludge  unit will not contaminate ground water if graound-
 water is not monitored at units that do not have a liner and leachate
 collection system (40 CFR 5-3.24(n)).
oped at relatively low cost if a qualified soil scientist is
available (see Section 6.4.2). A grid spacing should be
chosen that will provide sufficient data points for con-
touring, but not so many that field work cannot be com-
pleted  in a day or two. A general rule of thumb would be
20 to 30 soil observations using handheld equipment to
record the following information: (1) texture and thick-
ness of A horizon, (2) texture and thickness of E horizon
(if present),  (3) depth to B or C horizon, and (4) depth
to seasonal high and permanent water table. If a ground
survey is used to prepare the topographic base map for
the site (Section 6.4.1), placement of stakes at the
chosen grid spacing and measurement of actual eleva-
tion of the grid points would  facilitate field  work and
plotting of data observations.  Section 6.5.2 discusses
how data collected by this survey can be used to evalu-
ate soil attenuation capacity and the potential for pollut-
ant transport.

Three-Dimensional Mapping of Hydraulic Head

Accurate characterization of the ground-water flow sys-
tem requires  not only a delineation of the water table
surface, but also measurement of hydraulic head at
different depths in an aquifer. Figure 6-5 shows why this
is necessary, In areas of ground-water  recharge, hy-
draulic head  decreases with  depth (wells a and b in
Figure 6-5). In ground-water discharge zones, hydraulic
head increases with depth (wells dand ein Figure 6-5).
Areas where  lateral flow is dominant are characterized
by small changes in hydraulic head with depth. Further-
more,  variations in the hydraulic conductivity of different
aquifer materials cause changes in the  distribution of
hydraulic  head and, consequently, changes in the direc-
tion of ground-water flow. This effect is illustrated in
Figure 6-6 where piezometers (discussed below) have
been  set in three different aquifer materials at each
observation point. The water table surface (Unit A) indi-
cates  a general flow direction from an elevation of 210
ft on the west edge to 180 ft on the east edge. Unit C in
Figure 6-6, however, shows a head distribution favoring
ground-water flow south to southeast.  Section 6.5.2 dis-
cusses further use of flow nets to evaluate the direction
of ground-water movement based on three-dimensional
pressure  head measurements.

Pressure head is measured using a piezometer. The two
major types of piezometers are (1) open-tube or stand-
pipe piezometers, in which ground water rises to the
level dictated by the pressure head, and (2) pore pres-
sure piezometers, which measure pressure directly. Any
cased well  can  function as an  open-tube piezometer,
provided  that the borehole around the casing  is well
sealed and  the well screen or casing slotting at the
bottom is short (5 feet or less) so as  to prevent mixing
of hydraulic heads. Pore pressure piezometers can be
further classified as:
                                                    79

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                  RECHARGE AREA
                       a
                        ft   b
                                                                             DISCHARGE  AREA
                                                                                  d   e
                                                                                              SCREENED
                                                                                              INTERVAL
                                                                                                 X
                                                                                            X

Figure 6-5.  Cross-sectional diagram showing depth variations of water level as measured by piezometers located at various depths
            (Mills et al., 1985).


                                                                      Potentiometric Maps
                                                                         For Each Layer1
                                                                                                           C ,
                                   Piezometers                             Resultant Head Level Contour Maps

Figure 6-6.  Ground-water contour surfaces using multilevel piezometer measurements (Sara, 1994).
                                                         80

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• Electrical resistance piezometers use strain gauge
  technology to sense the pressure of a fluid applied
  to a diaphragm.

• Vibrating wire piezometers, which generate electrical
  signals at the surface as the tension in a wire that is
  connected  to a  diaphragm  situated  behind  a filter
  stone changes in response  to higher or lower pore
  pressure,

• Pneumatic  piezometers,  which  use  a  pressure
  transducer to measure changes that  water pressure
  has exerted against a diaphragm into which air has
  been forced.

• Hydraulic piezometers, which consist of one or two
  water-filled tubes that run from the surface to a ce-
  ramic or porous stone tip; pressure changes are read
  from a gage at the surface (mercury manometer,
  transducer, or Bourdon gage).

Pore  pressure probes can be driven  into the ground
manually or hydraulically (using a cone-penetration rig)
to obtain continuous  pore pressure profiles that also
allow interpretations of subsurface  stratigraphy (Figure
6-7). As shown in Figure 6-7, equilibrium pore pressure
is often inferred rather than measured directly, because
this requires  stopping the probe and waiting for equili-
bration to occur, which may take a long time (especially
in clays). However, in clean and dirty sands and gravels
with less than 40% fines measurements of equilibrium
pore  pressure is rapid and  useful. A series of poten-
tiometric maps with depth (as shown in Figure 6-6) could
be developed with relative ease, however, by stopping
to measure equilibrium pore  pressure at specified inter-
vals in  multiple probe  tests.  The advantage of this
method is that numerous hydraulic head measurements
can be obtained over a relatively short period. The cau-
tionary note  in Section 6.4.2 concerning grouting  of
boreholes applies here as well. Pore pressure probes
can also be driven to the desired depth without profiling
as .permanent monitoring installations.

The other simple way to develop hydraulic head profiles
with depth is to install permanent piezometer nests. This
involves  placing piezometers at different depths in a
cluster. The  simplest way to do this is to push a small-
diameter, open-hole drive-point or pore  pressure probe
attached to  a metal standpipe to the  desired depth.
These can be driven manually using a  weighted driver
(Figure 6-8a) or a crank driven device (Figure 6-8b).
Portable  power-driven drivers and truck-mounted hy-
draulic drivers such as those illustrated  in Figures 6-2a
and 6-3 also can be used to install piezometers.

The advantage of permanent piezometer installations is
that changes in  hydraulic head distributions with time
can be measured. Measurement of seasonal changes
in ground-water levels~and responses to rainfall events
are an important part of characterizing the ground-water
flow system. With open-hole piezometers such changes
are usually measured using a tape or electric water-level
probe. Measurements using permanent pore pressure
piezometers can be made manually by  reading the ap-
propriate gage or signal, or recorded automatically with
a datalogger. An advantage of open-hole piezometers is
that they also can  be useful for ground-water quality
monitoring (see Chapter 9). Pausing at  intervals during
the driving of the first piezometer in a cluster will provide
an indication as to whether it is located in a recharge,
discharge, or lateral-flow zone. These measurements
then can be used to determine the best  depth for place-
ment of shallower piezometers in the cluster.

If subsurface materials are soft enough to be penetrated
by drive points  (silts, sands,  clays) and course frag-
 Figure 6-7.  Typical pore pressure sounding diagram for a layered soil; u0 = equilibrium pore pressure (courtesy of Hogentogler &
           Co., Inc.).
                                                   81

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                         AT-11B
                         Drive Cap

                            Driver
                            Body
                                    Handle
                         AT-10B
                         Probe Rod
Figure 6-8. Manual piezometer installations methods: (a) weighted driver (courtesy of Geoprobe Systems); (b) crank-driven (courtesy
          of Hogentogler & Co., Inc.).
ments or very dense layers such as glacial till are ab-
sent, installation of piezometers is relatively inexpensive
(hundreds  vs.  thousands  of dollars  for conventional
monitoring well installations). If standard drilling equip-
ment such as hollow-stem augers must be used, costs
will be much higher but still less than for installation of
conventional monitoring wells if capsule-type piezome-
ters with flexible  tubing are used. Section 10.4.2  dis-
cusses installation of permanent ground-water quality
monitoring wells.

The location and number of multilevel piezometer meas-
urements or installations will depend on the complexity
of the site. At  a  minimum, measurements should be
taken at the highest and lowest  topographic points on
the site and at several intervening points.

6.4.4   Wetland Identification and Delineation

Site-specific investigations  of potential sewage sludge
surface disposal sites will often require a determination
of the presence or extent of wetlands. For example, U.S.
EPA (1990b) found that 79 percent of the  110 sanitary
landfills in  the  State of New York  for which National
Wetland Inventory (NWI) maps  were available, either
included or were within 1/4 mile of a wetland. Similarly,
U.S. EPA (1990a) in a study of 1,153 sanitary landfills in
11 states,  found that 72 percent contained wetlands or
were within 1/4 of a mile.

The term  wetlands includes swamps, marshes,  bogs,
and any areas 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
conditions. As noted in Section 6.3.3, the  presence or
absence of hydric soils  (e.g., soils that are wet long
enough to periodically produce anaerobic conditions) in
a soil survey of the site will provide a good indication of
whether a more detailed investigation will be required. If
a wetland  is determined to be on the site, its boundaries
must be accurately delineated.

Accurate wetland delineation typically requires  assess-
ment by a qualified  and experienced multidisciplinary
team 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 present. Many methods
have been developed for assessing wetlands. The main
                                                   82

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guidance manuals for wetland delineation for regulatory
purposes are the Corps of Engineers Wetlands Deline-
ation Manual (COE, 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 (USFWS, 1984).

Appendix C in U.S.  EPA (1990c)  provides  summary
information on more than 30 methods for assessment of
wetland functions and values. Phillips (1990) describes
a quantitative wetness index for use when  field indica-
tors of wetness are ambiguous or contradictory. Lyon
(1993)  may be useful as a supplemental reference for
wetland identification  and delineation. Finally,  Maus-
bach (1994) provides a recent review of the historical
development and current status of criteria developed by
the SCS for classification of wetland soils, and notes that
definitions are continuing to evolve as SCS develops
and tests regional indicators of hydric soils.

6.4.5  Floodplain and Other Hydrologic
       Characterizations

As  noted in Section 6.3.3, whether a site is  located
wholly  or in part within a 100-year floodplain  can be
initially determined using a  FEMA floodplain map or
SCS soil survey. If there is any reason to suspect  that
actual sewage sludge disposal will occur on the flood-
plain, more detailed investigations will be  required to
accurately delineate the floodplain boundary. If disposal
within the floodplain cannot be avoided, then the surface
disposal site must be  designed to include protective
measures such as embankments or levies so that active
sewage sludge units: (1) will not restrict the flow of the
100-year flood, (2)  will not reduce the temporary water
storage capacity of the fjoodplain, or (3) will  not result in
washout  of pollutants  that pose a hazard to  human
health and the environment.

Site-specific  floodplain  investigations  may  require
analysis of meteorological and streamflow records; up-
stream topography, soils, and geology; aerial  photo-
graph interpretation; and assessment of existing  and
anticipated changes in  watershed  land use. The Inter-
agency Advisory Committee on Water Data (Hydrology
Subcommittee, 1982) provides guidelines for determin-
ing flood flow frequency using stream gauge records.

The U.S. Army Corps  of Engineers (COE, 1982)  has
developed several  numerical models to: aid in the  pre-
diction of flood hydrographs (HEC-1); create water  sur-
face profiles  due to obstructions  for evaluating flood
encroachment potential (HEC-2); simulate flood control
structures (HEC-5); and gauge river sediment transport
(HEC-6). The HEC-2 model is not appropriate for simu-
lation of  sediment-laden  braided   stream  systems or
other intermittent/dry stream systems that are subject to
flash-flood events. Standard runoff and peak flood hy-
drograph methods would be more appropriate for such
conditions to predict the effects of severe flooding.

6.4.6  Geotechnical Characterization

Sewage sludge  monofills and dedicated surface dis-
posal sites that involve design of foundations, liners and
leachate collections systems, and dikes/embankments
will require detailed subsurface  exploration, including
sampling of subsurface solids and laboratory testing.

Subsurface exploration programs often use both indirect
and  direct methods, with direct methods required to
confirm indirect  observations.   Indirect  investigation
methods  include remote sensing techniques,  such as
aerial photograph  interpretation (Section  6.3.1),  and
geophysical techniques, such as DC resistivity, electro-
magnetic induction, ground-penetrating radar, and seis-
mic refraction. These methods do not require drilling or
excavation. Selection  of the proper geophysical  tech-
niques requires consideration of the purpose of the test,
the character of the subsurface materials, depth  limits
of detection and resolution of possible methods, and
susceptibility  of  methods to electrical or vibrational
noise. While geophysical procedures can provide  large
amounts  of data at a relatively low cost, they require
careful interpretation that must be carried out by quali-
fied experts only. Furthermore, geophysical data  must
be verified by direct procedures such as borings or test
pits.  Chapter 1 of U.S. EPA (1993c) provides additional
information on remote sensing and surface geophysical
methods.

Direct investigation methods include drilling boreholes
and  wells and excavating pits  and trenches. Direct
methods allow the site's geologic conditions to  be
examined and measured. Typically, boring logs should
provide descriptions of the soil strata and rock forma-
tions encountered, as well as the depth at which they
occur. In addition, the boring logs should provide stand-
ard penetration test results  for soils and  rock quality
designation results for rock core runs. The boring logs
also  should record the intervals for, and the results of,
any field hydraulic conductivity testing conducted in the
borings.

Foundation soil stability assessments require field in-
vestigations to determine soil strength and other soil
properties. In clayey materials, in situ field vane shear
tests commonly are conducted in addition to collection
of samples of subsurface material for laboratory testing
of engineering properties. Soil samples can be obtained
either by split spoon or thin-walled tube.  Split spoon
samples are disturbed and are of limited value other than
for identification and assessment of water content. The
thin-walled tube sample provides an undisturbed sample
that can be used for a wide variety of laboratory tests.
                                                   83

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Laboratory testing is conducted using representative soil
samples. Testing, as appropriate, to evaluate the embank-
ments, the foundation area, and areas under considera-
tion as a source for borrow material covers: (1) ASTM/
Unified  Soil Classification  System (ASTM  D2487-93,
Test Method for Classification of Soils for Engineering
Purposes), (2)  grain-size distribution, (3) shrink/swell
potential, (4) shear strength, (5) compressibility, (6) con-
solidation properties, (7) density and water content, (8)
moisture-density relationships, (9) dispersivity, and (10)
laboratory hydraulic conductivity. When evaluating foun-
dation materials and liner materials, additional signifi-
cant parameters for laboratory testing include cation
exchange capacity and mineralogy.

The scope of the subsurface exploration program will
vary depending on the complexity of the subsurface
geology, seasonal variability in site conditions, and the
amount of site information available. Typically, the inves-
tigator should  drill an  adequate  number  of borings
across the site to characterize the  underlying deposits
and  bedrock conditions and to establish  a reasonably
accurate subsurface  cross section. Depth of borings is
highly dependent on site-specific conditions. Typically,
however, the borings should extend below the antici-
pated site base grade or below the water table, which-
ever  is deeper.  A sufficient  number of water table
observation wells and piezometers should be installed
to define both the horizontal and vertical  ground-water
flow directions (Section 6.4.3). When subsurface hetero-
geneities are encountered that could lead to seepage or
loss in strength in the foundation, additional subsurface
exploration is sometimes necessary to identify and de-
termine the extent of these features.
U.S. EPA (1988a) provides more detailed guidance on
types of geotechnical information and on field and labo-
ratory methods required for design of surface disposal
sites; U.S. EPA (1986a) provides more detailed guid-
ance on design, construction, and evaluation of clay
liners. The following major references provide more de-
tailed information on subsurface exploration techniques
for geotechnical investigations: Bureau of Reclamation
(1989,  1990),  Hanna  (1985),   Hathaway  (1988),
Hvorslev (1949), USAGE (1984), and U.S. Naval Facili-
ties Engineering Command (1982).

Identification of Unstable Areas

U.S. EPA (1993d) classifies unstable areas that might
restrict suitability for solid waste disposal as natural and
manmade. Naturally unstable areas include:

• Expansive soils, which have a large percentage of
  clays with  a  high shrink-swell  potential (smec-
  tite/montmorillonite  groups,  vermiculites, bentonite)
  or with sulfate or sulfide minerals present in the soil,
  make poor foundations. Such soils are readily iden-
  tified by a soil survey. For example, any soils classi-
  fied as vertisols (which have a high shrink-swell po-
  tential) would  probably  be unsuitable at a surface
  disposal site. Expansive soils tend to be found in the
  arid western states.

• Soils subject to  rapid settlement (subsidence) also
  make poor foundations. Such soils include thick loess,
  unconsolidated clays, and wetland soils. Loess, found
  in the north central states, tends to compact when it
  is wetted.  Unconsolidated clays and wetlands, on the
  other hand, subside when water is withdrawn.

• Areas subject  to mass movement have  rock or soil
  conditions that are  conducive to downslope move-
  ment  of soil,  rock, and/or debris (either alone or
  mixed with water) under the influence  of gravity. Ex-
  amples of mass movement include landslides, debris
  slides and flows, and rock slides. These tend to occur
  most commonly on steep slopes,  but sometimes con-
  ditions on gradual slopes favor mass movement.

• Karst terrains  develop where soluble  bedrock (typi-
  cally limestone, but dolomite, and gypsum also might
  be subject to such  effects) forms  a  subterranean
  drainage system where flow is concentrated in con-
  duits. These areas tend to be characterized by cav-
  erns and  sinkholes and  subject to  unpredictable,
  catastrophic rock collapse. The presence of sinkholes
  and soluble bedrock at or near the surface are a clear
  indication of site unsuitability. The absence of obvious
  karst  geomorphic  features (i.e., sinkholes) where
  limestone  or other soluble bedrock is near the surface
  is not sufficient to determine stability.  Fracture trace
  analysis using aerial photographs is  an especially
  useful method for characterizing karst terrain (Section
  6.3.1). Additional  investigations,  perhaps using sur-
  face geophysical techniques also might be  required
  if no alternatives to siting in a karst area are available.

Examples of human-induced unstable areas include:

• The creation of cut and/or fill slopes during construc-
  tion of the sewage sludge surface disposal site can
  cause slippage of existing soil or rock. At most sites
  the amount of  earth-moving conducted is likely to be
  small enough that this will not be a  major concern.

• Excessive drawdown of ground water can cause ex-
  cessive settlement or bearing capacity failure of foun-
  dation soils. Again, this will not be an  issue at most
  sewage sludge surface disposal sites; however, if a liner
  and a leachate collection system are to be used, system
  design should  take this effect into consideration.

Another type of naturally unstable area includes disper-
sive  soils  where sodium-rich clays (which  often also
have a high shrink-swell) tend to disperse when wetted,
allowing a form  of subsurface erosion called piping.
If any of the above conditions exist at a  site and alter-
native sites with fewer problems are not available, more
                                                   84

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detailed geotechnical field investigations will likely be
required. U.S.  EPA  (1993d) provides more detailed
guidance on the approach that should be taken to as-
sess site stability and design approaches for designing
for stable slopes. U.S.  EPA (1987 and 1988a)  identify
specific data needs and field and laboratory methods for
geotechnical evaluation and design of different types of
engineered structures.

6.5   Data Analysis and Interpretation

Analysis  and interpretation of data from site-specific
investigations for a dedicated sewage sludge disposal
site focus on the following:
• Identification  of areas of shallow ground water and
  assessment of the ground-water flow patterns at the
  site (Section  6.5.1).
• Provision of data required for establishing routine pol-
  lution control  measures at the site, mainly  surface
  runoff controls (Section 6.5.2).
• Documentation of the presence or absence of special
  site conditions that might  impose special  regulatory
  restrictions (Section 6.5.3) and, if present, presenta-
  tion of data that show the limitations can be overcome
  by one or more engineering design approach  (Sec-
  tion 6.5.4).
Computer modeling (Section 6.5.5)  can facilitate all of
the types of analysis listed above.

6.5.1  Identifying Areas of Shallow Ground
       Water and Ground-Water Flow Net
       Analysis
The investigations described in Section 6.4.3 should
allow development of a relatively detailed water table
contour map, which  in combination with the site topo-
graphic map will facilitate development of  an  unsatu-
rated zone thickness isopach map. Such a map can be
used in several ways, including:  (1) to identify areas of
shallow ground water where it may be desirable to place
some fill  to increase  the depth of saturation  in  the sur-
face disposal site, or (2) to assess the relative attenu-"
ation capacity of the vadose zone within the  surface
disposal  site.
Ground-water flow net analysis is  a  relatively simple
graphical technique  for gaining an understanding of
ground-water flow patterns  using  water-table  surface
contour  maps  and three-dimensional hydraulic head
data collected  using procedures described  in  Section
6.4.4. As a first approximation, the general  direction of
ground-water flow at a site can be determined by draw-
ing flow lines perpendicular to the water table contours.
As illustrated in Figure 6-5, apparent directions of flow
may change with depth. Flow lines drawn perpendicular
to ground water equipotential contours should  be con-
sidered only a first approximation because anisotropy in
the aquifer (e.g., sites where horizontal hydraulic con-
ductivity  exceeds  vertical hydraulic  conductivity) will
cause flow lines to diverge from the perpendicular. Fig-
ure 6-9 illustrates such a divergence in a fractured rock
aquifer where vertical hydraulic conductivity is five times
the horizontal hydraulic conductivity.

In ground-water recharge areas  (i.e., hydraulic head
decreases with increasing depth), it is important to rec-
ognize that pollutants entering the ground water will tend
to move  downward in the aquifer as well as laterally.
Figure 6-10 illustrates this effect and shows how flow net
analysis  can be used to estimate pathlines where lay-
ered aquifer materials have different  hydraulic conduc-
tivities. In this figure, a cross section  of the aquifer has
been drawn using  the borehole logs  from three, multi-
level piezometer installations, and equipotential lines
drawn  using hydraulic head measurements at four  or
five levels in each piezometer. The angle of refraction of
flow or equipotential lines is determined from the ratio of
the hydraulic conductivities, which equals the ratio of the
tangents of the angles formed by the flow lines. Figure
6-10 illustrates that the downward component of pollut-
ant transport increases as hydraulic conductivity de-
creases. A significant implication of  this effect is that
downgradient ground-water  monitoring wells that are
screened in the upper portion of an aquifer may miss a
pollutant plume in  a recharge area, unless the aquifer
has very high hydraulic conductivity.
Flow net construction and analysis requires knowledge
of the  hydraulic conductivity of aquifer  materials. Hy-
draulic conductivity values also are required to estimate
how rapidly pollutants  might  move  if they enter the
ground-water system. References in Table 6-7 should
be consulted for guidance on the selection of aquifer test
methods  if field measurement of aquifer properties is
required.
This section emphasizes flow net analysis because it
provides a maximum amount of information about the
hydrogeologic system at relatively low cost if procedures
for collecting three-dimensional hydraulic head meas-
urements described in Section 6.4.4 are used. Flow nets
can readily be constructed manually, although use  of
computers for contouring data and graphic analysis can
facilitate  the  process.  Cedergren (1989), U.S. EPA
(1986b)  and Sara (1994) are recommended for more
detailed  guidance  on construction and interpretation of
flow nets. Flow net construction in anisotropic aquifers
requires special procedures, which are covered in these
references. Use of flow nets for placement of ground-
water monitoring wells is discussed in Chapter 10.

6.5.2   Other Geotechnical Considerations

As noted in Section 6.4.6, some sewage sludge surface
disposal sites will not require extensive geotechnical
                                                   85

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                          ISOTROPIC AQUIFER
                   water-table   /(=> %
                    contours
                                    /
                                      s*
                                             $
                                                        ANISOTROPIC AQUIFER
                                                           water-table
                                                             contours
                                                  KY
                                                  b:
Figure 6-9.  Effect of fracture anisotropy on the orientation of the zone of contribution to a pumping well (U.S. EPA, 1991b).
p.i7n p.-t7h
P I7c' P I7d
f-i/c f-i/g
                   R.OW NET FOR SILTY SAND.SAND UNITS & BEDROCK WITH DOWNWARD 1 1EADS
                                              Pioynmotorc
                                              riezometers
                                              p'18a' p-18b                        Piezometers
                                              P-18C, P-i8d                        p-i9a, P-l9b
                                                         ._— GROUND SURFACE    p.-\QC] P-19d
         .  . „;> 20 m   SILTY SAND (K,ซSXIO
                                                                                                20
                                                                                                18
                                                                                                          12
                                                                                                          10
                                                                                                          8
            10
           . I .
                   Mil
                      zo
  HORIZONTAL SCALE - METERS
                                                                             10m
                                                                     LEGEND
                                                                     	 GROUND WATER EOUIPOTENTiAL
                                                                       Q   PIEZOMETER LOCATION
                                                                           SCREENED SECTION
                                                                     I'.V.'.Vj  POTENTIALLY TRANSM'SSIVE LAYERS
                                                                           HEAD ELEVATION AT CENTER OF SCREENS
                                                                           FLOW LINE
Figure 6-10.  Example flow net construction: Three layers with downward flow (Sara, 1994).
characterization because surface runoff controls will be    to control surface runoff, then the topographic map and
the only routinely required engineered features. The site
topographic map will provide  most of the information
required.  If construction of sediment ponds is required
                                                geologic cross sections showing depth of unconsoli-
                                                dated material are required to identify areas of suitable
                                                soil material for the impoundment.  U.S. EPA (1986a),
                                                       86

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U.S. EPA (1988a), and U.S. EPA (1993d) should be
consulted for guidance when sewage sludge monofills
or dedicated surface disposal sites require construction
of liners and leachate collections systems and dikes or
embankments.

6,5.3   Special Site Conditions

The initial  site selection process (Chapter 4) should
have eliminated sites from consideration where unfavor-
able site conditions (e.g., floodplains, wetlands, or un-
stable  geology or soils), would make a site unsuitable.
If all possible sites are problematic in one way or an-
other,  field investigations should  have focused on
accurate delineation of problematic areas. Analysis and
interpretation of information obtained by  these investi-
gations should focus on identification of the site or sites
where impacts of disposal or mitigation costs are mini-
mized. In the case of siting within floodplains, the mini-
mal disturbance of the hydrologic regime of the floodplain
must be demonstrated, as discussed in Section 6.4.5. If
wetlands must be disturbed, the  unavailability of a
less-damaging alternative must be demonstrated. If site
stability is a concern, engineering  cross-section  and
design  calculations  should  demonstrate  adequate
safety factors based on site geotechnical characteristics
and reasonable design assumptions:

6.5.4   Computer Modeling

Numerous computer models have  potential  value for
assessing the possibility of environmental impacts from
surface disposal of sewage sludge and  for designing
systems for minimizing impacts.  This section identifies
relatively simple computer models that have been iden-
tified by U.S.  EPA as  being  appropriate for use in as-
sessment and design  of surface disposal sites, where
simplifying assumptions are appropriate. These include:

• The Hydrologic Evaluation of Landfill Performance
  (HELP)  model (see discussion on HELP  model  in
  Chapter 7) is a water budget model for evaluating the
  quantity of leachate generation.

• The  VADOFT  module  of the   Risk of  Unsatu-
  rated/Saturated Transport and  Transformation  of
  Chemical  Concentrations  (RUSTIC)  model  (U.S.
  EPA, 1989a and  1989b),  a vadose zone  chemical
  transport model and AT123D (Yeh, 1981), a saturated
  zone chemical transport model, were  used by  U.S.
  EPA for the risk assessment modeling that developed
  the Section 503 sludge  pollutant limits.

• EPA's  Multimedia  Exposure  Assessment Model
  (MULTIMED) is intended to be used at surface dis-
  posal sites where fate and transport modeling is re-
  quired to demonstrate that performance criteria can
  be met,  provided that the site allows use of certain
  simplifying assumptions (U.S. EPA,  1993d). MUL-
  TIMED contains modules that estimate pollutant re-
  leases to air, soil, ground water, and surface water.
  U.S. EPA (1993a) and U.S. EPA (1992) provide docu-
  mentation and  guidance on how to use the model.

All  of the  above models use arithmetic  or analytical
solutions that assume relatively simple hydrologic sys-
tems (e.g., as isotropic, homogeneous unsaturated, and
saturated zones), and only should be used if site condi-
tions justify making simplifying assumptions. If they are
not justified, then more sophisticated numerical com-
puter models should be used. Appendix D in U.S. EPA
(1993a)  provides information on 17 commonly used
vadose zone flow and transport models. Recommended
major EPA documents that provide information on selec-
tion and use of subsurface flow and transport modeling
include: U.S. EPA (1985), U.S. EPA (1988b), and U.S.
EPA (1993f). U.S. EPA (1993b)  provides a detailed re-
view of leachate generation and migration models.


6.6   References

 1.  American Society for Testing and Materials (ASTM). 1994.  Draft
    standard guide to site characterization for  environmental pur-
    poses. Philadelphia, PA: ASTM.

 2.  Boulding, J.R. 1994. Description and sampling of contaminated
    soils: Afield guide, 2nd ed. Chelsea, Ml: Lewis Publishers.

 3.  Bureau of Reclamation. 1990. Earth Manual, 3rd ed, Part 2. U.S.
    Department of the Interior, Bureau of Reclamation, Denver, CO.
    [Part 1 consists of a 1990 reprint of the first 3 chapters of the
    1974 2nd edition.]

 4.  Bureau of Reclamation. 1989. Engineering geology field manual.
    U.S. Department of the Interior, Bureau of Reclamation, Denver, CO.

 5.  Cedergren, H.R. 1989. Seepage, drainage, and flow nets, 3rd
    ed. New York, NY: John Wiley & Sons.

 6.  Corps of Engineers (COE). 1982. HEC-1, HEC-2, HEC-5, HEC-6
    computer programs. Davis, CA: U.S. COE Hydrologic Engineer-
    ing Center.

 7.  Corps of Engineers (COE). 1987. Wetlands delineation manual. Tech-
    nical report Y-87-1. Vicksburg, MS: Waterways  Experiment Station.

 8.  Dodd,  K., H.K. Fuller, and P.P. Clarke, eds.  1989. Guide to ob-
    taining USGS information. U.S. Geplogical Survey Circular 900.

 9.  Federal Interagency Committee for Wetland Delineation. 1989.
    Federal manual for identifying and delineating jurisdictional wet-
    lands.  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 Conser-
    vation  Service, Washington, DC.

10.  Gale Research Company. 1985. Climates of the states: National
    Oceanic and Atmospheric Administration narrative summaries,
    tables, and maps for each state, with overview of state climatolo-
    gist programs, 3rd ed. Detroit, Ml: Gale Research Company.

11.  Giefer, G.J., and O.K. Todd, eds. 1976. Water publications of state
    agencies, first supplement, 1971-1974. Syosett, NY: Water Infor-
    mation Center.

12.  Giefer, G.J., and O.K. Todd, eds. 1972. Water publications of state
    agencies. Syosett, NY: Water Information Center.
                                                     87

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13. Grawiewska, A., ed. 1969. KWIC index of rock mechanics litera-
    ture published before 1969. New York, NY: American Institute of
    Mining. Metallurgical, and Petroleum Engineering.
14. Hanna, T.H. 1985. Reid instrumentation in geotechnical engi-
    neering. Ciausthal, Germany: Trans Tech Publications.
15. Hathaway, A.W.  1988. Manual  on subsurface investigations.
    Washington, DC: American  Association  of State Highway and
    Transportation Officials.
16. Hatch, W.L. 1988. Selective  guide to climatic data sources. Key
    to  meteorological records documentation no. 4.11. Asheville,
    NC:NOAA National Climate Data Center.
17. Hvorslev, M.J.  1949.  Subsurface exploration  and sampling of
    soils. New York, NY: Engineering Foundation.
18. Hydrology Subcommittee. 1982. Guidelines for determining flood
    flow frequency. Bulletin #17B. Reston, VA: Interagency Advisory
    Committee on Water Data, USGS Office of Data Coordination.
19. Jenkins, J.P., and E.T. Brown, eds. 1979. KWIC index of rock
    mechanics  literature,  part 2, 1969-1976. New York,  NY: Per-
    gamon Press.
20. Kaplan, S.R. 1965. A guide to information sources in mining, min-
    erals, and geosciences. New York, NY: Interscience Publishers.
21. Lyon, J.G. 1993. Practical handbook for wetland identification and
    delineation. Boca Raton, FL: Lewis Publishers.
22. Makower, J., ed. 1992. The map catalog, 2nd ed. New York, NY:
    Random House.
23. Mausbach,  M.J. 1994. Classification of wetland soil for wetland
    identification. Soil Surv. Horiz. 35(1):17-25.
24. National Technical Committee for Hydric Soils.  1991. Hydric soils
    of  the United States. Misc.  Publ. 1491. Washington,  DC: U.S.
    Department of Agriculture, Soil Conservation Service.
25. Nielsen, D.M., ed. 1991. Practical handbook of ground-water
    monitoring.  Chelsea, Ml: Lewis Publishers.
26. Phillips, J.D. 1990. A saturation-based model of relative wetness
    for wetland  identification. Water Resour.  Bull. 26(2):333-342.
27. Sara, M.N. 1994. Standard handbook of site assessment for solid
    and hazardous waste facilities. Boca Raton, FL: Lewis Publishers.
28. Soil Survey Staff. 1992. Keys to soil taxonomy, 5th ed.  SMSS
    technical monograph no. 19. Blacksburg, VA: Pocahontas Press.
29. U.S. Army Corps of Engineers (USAGE). 1984. Engineering and
    design: Geotechnical investigation. Engineer manual EM 1110-1-
    1804. Washington, DC: U.S. Army Corps of Engineers.
30. U.S. EPA. 1993a. MULTIMED, the multimedia exposure assess-
    ment model for evaluating the  land disposal  of wastes:  Model
    theory. EPA/600/R-93/081  (NTIS PB93-186252).
31. U.S. EPA. 1993b. Leachate  generation and migration at Subtitle
    D facilities:  A summary and review of processes and mathemati-
    cal models. EPA/600/R-93/125 (NTIS PB93-217778).
32. U.S. EPA. 1993c. Subsurface field characterization and monitor-
    ing techniques: A desk reference guide, Vol. I. Solids and ground
    water. EPA/625/R-93/003a; Vol. II. The vadose zone, field screen-
    ing, and analytical methods. EPA/625/R-93/003b.
33. U.S. EPA. 1993d. Solid waste disposal facility criteria: Technical
    manual. EPA/530-R-93-017  (NTIS PB94-100450).
34. U.S. EPA. 1993e. RCRA ground-water monitoring: Draft technical
    guidance. EPA/530/R-93/001 (NTIS PB93-139350).
35. U.S.  EPA. 1993f.  Compilation of   ground-water  models.
    EPA/600/R-93/118 (NTIS PB93-209401).
36. U.S. EPA. 1992. A Subtitle D landfill application manual for the
    multimedia   exposure   assessment   model  (MULTIMED).
    EPA/600/R-93/082 (NTIS PB93-185536).

37. U.S. EPA. 1991 a. Description and sampling of contaminated soils:
    Afield pocket guide. EPA/625/2-91/002. Available from CERI.

38. U.S. EPA. 1991b. Delineation of wellhead protection areas in
    fractured rocks. EPA/570/9-91/009.

39. U.S. EPA. 1991c. Site characterization for subsurface remedia-
    tion. EPA/625/4-91/026.

40. U.S. EPA. 1990a. Proximity of sanitary landfills to wetlands and
    deepwater habitats: An evaluation and comparison of 1,153  sani-
    tary landfills in 11 states. EPA/600/4-90/012 (NTIS PB90-216524).

41. U.S. EPA. 1990b. Proximity of New York sanitary landfills to wet-
    lands and deepwater habitats. EPA/600/4-89/046 (NTIS PB90-
    155649).

42. U.S. EPA. 1990c. Water quality standards for wetlands: National
    guidance. EPA/440/S-90/011.

43. U.S. EPA. 1989a. Risk of unsaturated/saturated transport and
    transformation of chemical concentrations (RUSTIC), Vol. 1. The-
    ory and code verification. EPA/600/3-89/048a.

44. U.S. EPA. 1989b. Risk of unsaturated/saturated transport and
    transformation  of  chemical concentrations (RUSTIC), Vol.  2.
    User's  guide. EPA/600/3-89/048b.

45. U.S. EPA. 1988a. Guide to technical resources for the design of
    land disposal facilities. EPA/625/6-88/018.

46. U.S. EPA. 1988b. Selection criteria for mathematical models used
    in  exposure assessments: Ground-water models. EPA 600/8-
    88/075 (NTIS PB88-248752).

47. U.S. EPA. 1987. Technology briefs: Data requirements for select-
    ing remedial action technology. EPA/600/2-87/001.

48. U.S. EPA. 1986a. Design, construction, and evaluation of clay
    liners for waste management facilities. Draft technical guidance
    document. EPA/530-SW-86-007F (NTIS PB89-181937).

49. U.S. EPA. 1986b. Criteria for identifying areas of vulnerable hy-
    drogeblogy under the Resource Conservation and Recovery Act,
    Appendix  B. Ground-water flow net/flow line  construction and
    analysis, interim final. EPA/530/SW-86/022B (NTIS PB86-224979).

50. U.S. EPA. 1985. Modeling remedial actions at uncontrolled haz-
    ardous waste sites. EPA 540/2-85/001  (NTIS PB85-211357).

51. U.S. Fish and Wildlife Service (USFWS). 1984. An overview of
    major wetland functions and values. FWS/OBS-84/18.

52. U.S. Geological Survey. 1978. Preliminary young fault  maps. Mis-
    cellaneous field investigations MF-916.

53. U.S. Naval Facilities Engineering Command. 1982. Soil mechanics
    design manual, Vol. 7.1. NAVFAC DM-7.1, Department of the  Navy.

54. Vepraskas, M.J. 1992. Redoximorphic features for identifying
    aquatic conditions. North Carolina Agricultural  Research Service
    technical bulletin 301. Department of Agricultural  Communica-
    tions, North Carolina State University, Raleigh, NC.

55. Ward,  D.C. 1972. Geological reference sources: A subject and
    regional bibliography of publications and maps in the geological
    sciences. Metuchen, NY: Scarecrow Press.

56. Yeh, G.T. 1981. AT123D: Analytical transient one-, two-, and
    three-dimensional simulation of waste transport in  the aquifer
    system. Environmental Sciences Division Publ. No.  1439. Oak
    Ridge, TN: Oak Ridge National Laboratory.
                                                              88

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                                             Chapter 7
                                               Design
7.1   Purpose and Scope

The objective of a surface disposal site design is to
direct and guide the construction and ongoing operation
of the disposal site. A design should ensure:

• Compliance with pertinent regulatory requirements.

• Adequate protection of public health and the environment.

• Cost-efficient utilization of site manpower, equipment,
  and storage volume.

A design package (consisting of all design documents)
should be prepared to provide a record of the site de-
sign. These may consist of drawings, specifications, and
reports.

The purpose of this chapter is to provide guidance on
the design of a surface disposal site. The organization
of specific topics addressed in this chapter is outlined in
Figure 7-1.

7.2   Regulatory  Requirements

7.2.1  Part 503

Many types of active  sewage sludge units (monofills,
dedicated surface disposal sites, piles and mounds, and
impoundments) are covered by the Part 503 Subpart C
regulation. The  Part 503 regulation includes manage-
ment practices  that must  be  followed when sewage
sludge is placed on an active sewage sludge unit. These
management practices help protect human health and
the environment from the  reasonable anticipated ad-
verse effects of pollutants in sewage sludge. Several of
the management practices required under Subpart C
influence the design  of  active sewage sludge units.
Management practices influencing the design of these
units are summarized as follows (for more detail, see
U.S. EPA, 1994):

• Runoff from an active sewage sludge unit must be
  collected and disposed of properly.  Runoff collection
  systems must be capable of handling a 25-year, 24-
  hour storm event.

• When  an active sewage sludge unit has a liner,
  leachate must be collected and disposed of properly.
• When an active sewage sludge unit is covered daily,
  Concentrations of methane gas must be monitored in
  air in any structure within the site and in the air at
  the property line of the surface disposal site.

• Sewage sludge placed in an  active sewage sludge
  unit must not contaminate an aquifer.

Another management practice required under Subpart
C requires the owner/operator of surface disposal sites
to  restrict public access. Management practices influ-
encing the siting and end uses of active sewage sludge
units are discussed in Chapters 4 and 10, respectively.

Two of the management practices listed above refer to
active  sewage  sludge  units with liners and leachate
collection systems and to units with covers.

• A liner is a layer of relatively impervious soil, such as
  clay, or a synthetic material that covers the bottom of
  an active sewage sludge unit with  a hydraulic con-
  ductivity of 1  x 10"7 cm/s  or less. The liner prevents
  the downward movement  of liquid in the active sew-
  age sludge unit from seeping into the ground water
  below.

• A leachate collection system is a system or device
  installed immediately above a liner,that collects and
  removes  leachate  (liquid waste from  rainfall  that
  seeps  through the contents  of the active sewage
  sludge unit).

• A cover is soil or other material placed over the sew-
  age sludge.

Sewage sludge placed on an active sewage sludge unit
with a  liner and leachate collection system does not
have to meet pollutant limits, based on the assumption
that those systems prevent pollutants from migrating to
the ground water.

Sewage sludge placed on an active sewage sludge unit
without a liner and leachate collection system must meet
the pollutant  limits for  arsenic,  chromium,  and  nickel
established under the Part 503 regulation. There are two
options for the pollutant limits (U.S. EPA, 1994):

• The  first  option is to make sure that the levels of
  arsenic, chromium, and nickel are not above the lev-
                                                  89

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                                           Section 7.2: Regulatory Requirements
                                           Section 7.3: Permitting Requirements
                                                        _L
                                   I  Section 7.4: Design Methodology and Data Compilation
               Section 7.5: Design for Monofills,
              Impoundments, and Piles and Mounds
                     Foundation Design
MonofiH


Surface
Impoundments
and Lagoons

Piles!
and
Mounds
                 Slope and Stability Analyses
                          JL
                      Uner Systems
                          I
                 Leachate Collection Systems
Section 7.6: Codisposal
          Design
Sludge/Solid Waste Mixture
                                                    Daily Cover Material
                                                    Sludge as Final Cover
Section 7.7: Dedicated Surface
         Disposal
  Natural Liner or Compliance
    with Pollutant Limits
                                                                                       _L
                                                                             No Contamination of Aquffiers
                                                                                 Land Area Needs
                              Proximity to Community
                                  Infrastructure
                                                                               Climate Considerations
                                                                                Beneficial DSD Sites
                                          Section 7.8: Environmental Safeguards
                                                   Leachate Controls
                                                 Run-on/Runoff Controls

                                                         '
                                                Explosive Gases Controls
Section 7.9: Other Design Features
Access

Soil Availability
—

Special Working
Areas

—
Building and
Structures

—
Utilities [—
Lighting
-1 Wash Rack


Figure 7-1.  Organization of Chapter 7, Design.
  els listed in Table 3-6, which are based on the dis-
  tance between the active sewage sludge unit bound-
  ary and the property line of the surface disposal site.

• The second option is to meet the site-specific pollut-
  ant limits for arsenic, chromium, and nickel,  if site-
  specific limits  have  been  set  by the  permitting
  authority.

(See Chapter 3 for more information on pollutant limits
for sewage sludge placed in surface disposal sites.)

7.2.1.1    Collection of Runoff

Runoff  is rainwater or  other liquid that drains over the
land and runs off  of the land  surface. Runoff from a
         surface disposal site might be contaminated with sew-
         age sludge or sewage sludge constituents. Runoff from
         an active sewage sludge unit  must be collected and
         disposed  of according to permit requirements of  the
         National   Pollutant  Discharge  Elimination   System
         (NPDES) and any other applicable requirements. Under
         the requirements of the Part 503  rule the runoff collec-
         tion system of an active sewage sludge unit must have
         the capacity to handle runoff from a 24-hour,  25-year
         storm event (a storm that is likely to occur once in 25
         years for a 24-hour period). This  requirement  helps
         ensure that runoff  (which may contain  pollutants) from
         an active sewage sludge unit site is not released into the
         environment. The peak flow of water and the total runoff
         volume of water during the 24-hour, 25-year storm must
                                                      90

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be calculated to properly size stormwater controls that
will be adequate to collect runoff from this storm (U.S.
EPA,  1994). (See Section 7.8.2 for design information
on runoff collection systems.)

7.2.1.2   Collection of Leachate

Leachate is fluid from excess moisture in sewage sludge
or from rainwater percolating down through the active
sewage sludge unit  from the land surface. Depending
on the pollutant content of the sewage.sludge, leachate
may contain substances such,as metals or organic
chemicals. If an active sewage sludge unit has a liner
and leachate collection system, two management prac-
tices in the Part 503 regulation apply (U.S. EPA, 1994).

The  first  management  practice  requires   that  the
leachate collection system be operated and maintained
according to design  requirements and engineering rec-
ommendations. The owner/operator of the surface dis-
posal site is responsible for ensuring that the system is
always operating according to design specifications and
is properly and routinely maintained (e.g., pumps are
periodically cleaned and serviced;  the system is peri-
odically inspected to detect clogs and flushed to remove
deposited solids).

The second management practice requires that leachate
be collected and disposed of according to applicable
requirements.  Leachate   should   be collected  and
pumped out by a system placed immediately above a
liner. If leachate is discharged to surface water as a point'
source, then an NPDES permit  is required. Otherwise,
leachate may be irrigated on land adjacent to the active
sewage sludge unit or discharged to a publicly owned
treatment works (POTWs). It is  recommended that the
leachate be tested to determine whether some kind of
treatment is appropriate before being disposed of.

Both management practices must be followed while the
unit is active and for 3 years after the unit closes or for
a longer period if required by the permitting authority.

These management practices help prevent pollutants in
sewage sludge placed on an active sewage sludge unit
from being released into the environment. For example,
if leachate was not collected regularly, or if the leachate
collection system was not operated and maintained
properly, then the liner could be damaged by the weight
of the leachate  pressing against it, and the leachate
could leak into the environment. Management practices
concerning the collection of leachate only apply to active
sewage sludge  units  with a liner. The Part 503  rule
regulates active sewage sludge units without liners and
leachate collection systems through the pollutant limits
discussed in Chapter 3 and through other management
practices in the  regulation.  (See  Sections 7.5.6  and
7.5.7 respectively for design information on liners and
leachate collection systems.)
 7.2.1.3  Limitations on Methane Gas
         Concentrations

 The Part 503 regulation contains a management prac-
 tice that limits concentrations of methane gas in air
 because of its explosive potential. Methane, an odorless
 and highly combustible gas, is generated at an active
 sewage sludge unit when sewage sludge is covered by
 soil or other material (e.g., geomembranes), either daily
 or at closure. The gas can migrate and be released into
 the environment. To protect site personnel and the pub-
 lic from risks of explosions, methane gas must be moni-
 tored continuously within any structure;on the site and
 at the property line of the surface disposal site. Air at
 surface disposal sites where active sewage sludge units
 are covered (either daily or at closure) must be moni-
 tored continuously for  methane gas; when active sew-
 age sludge units are not covered, air does not  have to
 be monitored continuously for methane gas (U.S. EPA,
 1994).

 This management practice limits the amount of methane
 gas in air in both active and closed sewage sludge units.
 When a cover is placed on an active sewage sludge unit,
 the methane gas concentration in air in any structure
 within the  property line of a surface disposal site must
 be less than 25% of the lower explosive limit (LEL). The
 LEL is the lowest percentage  (by volume) of methane
 gas in air that supports a flame under certain conditions
. (at 25ฐC and atmospheric pressure). For methane, the
 LEL is 5%. Therefore, if 5% of the LEL is 50,000  ppm
 methane, then air in any structure within the property
 line must not exceed 12,500 ppm methane (U.S. EPA,
 1994).

 A methane gas  monitoring device  must be placed in
 such a way that air inside any structure on the property
 is continuously  measured for methane  gas and the
 measurement can be read by any individual before en-
 tering the structure. (The act of entering the  building
 could create enough of a spark to ignite explosive levels
 of methane gas.)

 For air at the property line of a'surface disposal site with
 a covered sewage sludge unit, the limit for methane gas
 concentration is  the LEL (i.e., 5%). In some cases, the
 permitting authority may determine that a methane gas
 monitoring device at one downwind location on the prop-
 erty line is adequate to meet this requirement because
 the wind patterns are consistent. In other cases, where
 wind conditions at the site are highly variable, more
 than one device may be necessary to provide adequate
 protection.

 Methane gas concentrations must be  monitored at all
 times when an active sewage sludge unit is  covered
 daily and for 3 years after the last active sewage sludge
 unit closes if a final cover is placed on the active sewage
 sludge unit.  If unstabilized sewage sludge is placed on
                                                  91

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sn active sewage sludge unit, the permitting authority
may require air to be  monitored for methane gas for
longer than 3 years after closure because of the higher
potential for methane gas generation with unstabilized
sludge (U.S. EPA, 1994).

Methane monitoring devices allow the user to read the
level of methane as a percent of the LEL. Some can be
equipped with alarms, which may be desirable in struc-
tures with a higher potential for collecting methane gas.
Various methods (e.g., venting systems, positive or
negative air pressure systems) are available to control
methane gas concentrations if they exceed the  limits.
(See Section 7.8.3 for  information on explosive gases
control.)

7.2.1.4  Restriction of Public Access

Public access to a surface disposal site must be re-
stricted while the site contains an active sewage sludge
unit and for 3 years after the last active  sewage sludge
unit closes (U.S. EPA, 1994). This management practice
helps to minimize public contact  with  any  pollutants,
including pathogens, that may be present  at surface
disposal  sites. It  also keeps the public away from an
area with the potential for methane gas explosions, as
discussed above. (See Section 7.9.1 for design informa-
tion on access restrictions.)

7.2.1.5   Protection of Ground Water

This management practice  states that sewage sludge
placed in an active sewage sludge unit must not con-
taminate an aquifer. "Contaminate an  aquifer" in  this
instance means to introduce a substance that can cause
the level of nitrate in  ground water to increase above a
certain amount. This management practice also  re-
quires that proof  be obtained that ground water  is not
contaminated. This proof must be either (1) the results
of a ground-water monitoring  program developed by a
qualified  ground-water scientist, or (2) certification by a
ground-water scientist  that ground  water will not be
contaminated by the placement of sewage sludge on an
active sewage sludge unit.

The certification option  usually is obtainable only if the
active  sewage sludge  unit has a liner and leachate
collection system. It is generally infeasible for a ground-
water scientist to certify that ground water will not be
contaminated in the absence of a liner unless ground
water is very deep and there is a natural clay layer or
unless the amount of material placed on the site is quite
low. (See Chapter 4 for more information on the protec-
tion of ground water at surface disposal sites.)

7.2.2  Part 258

EPA's Solid Waste Disposal Facility Criteria, 40 CFR
Part 258, regulate the design of municipal solid waste
(MSW) landfill units, including codisposal landfills. Sew-
age sludge placed in an MSW landfill must:

• Pass the paint filter liquids test (i.e., does not contain
  free liquids).

• Not be a hazardous waste or PCB waste.

These requirements are discussed in Section 3.4.3. In
addition,  the treatment works  must ensure that the
sludge goes to a state-permitted landfill. Codisposal is
discussed in more  detail  in Section 7.6, Design for
Codisposal With Solid Waste.

7.2.3 State Rules Applicable to the Disposal
       of Sewage Sludge

Part 503 does not replace any existing state regulations;
rather, it sets minimum national standards for the use or
disposal of sewage sludge. It is important to note that
persons disposing of sewage sludge are subject to  state
and possibly local regulations in addition to federal regu-
lations. Furthermore, these state and other regulations
may be more stringent than  the  Part  503 rule,  may
define sewage sludge differently, or may regulate certain
types of sewage sludge more stringently than does the
Part 503 rule. In addition, some states have established
requirements for their MSW landfills, including restric-
tions on codisposal, that are more stringent than on the
federal requirements. (For example, some states  have
set loading  limits for sludge at MSW landfills.)  In all
cases, persons wishing to use  or dispose of sewage
sludge must  meet all applicable federal and state re-
quirements.

For information on specific state sewage sludge regula-
tions, the  reader should consult the appropriate  state
sewage sludge permitting authority, or state septage
coordinator.  EPA regional sewage  sludge  and septage
coordinators are listed in Appendix B.

States can change their regulations to meet the  mini-
mum federal standards. EPA will be working with states
to encourage them to gain approval for administering the
Part 503 rule. States can apply  to EPA for approval of
their sewage sludge program at any time, but they are
under no obligation to do so. See Chapter 1 for more
information on the relationship of  the federal require-
ments to state requirements.

7.3  Permitting Requirements

Many regulatory and approving agencies require per-
mits before a sewage sludge unit can be constructed or
operated. Accordingly, all pertinent agencies should be
contacted  early in the design phase to: identify regula-
tions impacting on the prospective sewage sludge dis-
posal site;  determine the extent, detail, and format of the
application; and, obtain any permit application forms.
Once this  information has been collected, the design
                                                  92

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can proceed in a more efficient manner toward the goal
of receiving the necessary permits.

Before proceeding to the final design it is advisable to
recontact regulatory agencies who were contacted dur-
ing the site selection process and others to obtain all of
their requirements and procedures for permit application
submittals. This also will provide an opportunity to dis-
cuss design concepts, get questions answered, and
determine any special or new requirements. Mainte-
nance  of  close  liaison with federal, state, and  local
regulatory officials throughout the design effort is nor-
mally helpful in  securing a permit without excessive
redesigns.

Requirements  and permits  relevant to sewage sludge
surface disposal sites exist on the federal,  state, and
local levels.


7.3.1   Federal Permits

Federal permits required for sewage sludge surface
disposal sites include:

• U.S. EPA Interim Sewage Sludge Application cover-
  ing sewage sludge  use or  disposal  standards re-
  quired under Part 503. Appendix A outlines the type
  of information that should be provided in  this permit
  application.

• National  Pollutant  Discharge  Elimination System  .
  (NPDES)  permit required for location of a sludge sur-
  face disposal site in wetlands. It is also required for
  any point source discharges from surface disposal sites.

• Army Corps of Engineers Permit (a dredge and fill
  permit) required for the  construction  of  any  levee,
  dike, or other type of containment structure to  be
  placed  in  the water at a surface disposal site located
  in wetlands.

• Office of Endangered Species permit may be required
  from the Fish  and Wildlife Service, U.S. Department
  of the Interior, for location of surface disposal sites in
  critical habitats of endangered species.


7.3.1.1   Self-Implementing Nature of  the Part 503
          Rule

The  Part  503 rule  is  self-implementing—thai  is,
owner/operators of surface disposal sites must comply
with the Part 503 rule (including the compliance dates
listed in Table 1-2 in Chapter 1), even if they have not
been issued a permit covering sewage sludge surface
disposal requirements. Similarly, EPA (or an approved
state) can take enforcement actions directly against per-
sons who violate the Part 503 requirements.
7.3.1.2   Who Must Apply for a Permit?

All sewage sludge surface disposal site owner/operators
must apply for a permit covering sewage sludge disposal
standards (U.S. EPA, 1994). Appendix A lists the type of
information that should be provided in a permit application.

In most cases, Part 503 requirements will  be incorpo-
rated over time into NPDES permits issued to POTWs
and  other treatment works treating domestic sewage
(U.S. EPA, 1994). As dictated by the permitting priorities
of EPA Regions and approved states, "sludge-only" per-
mits covering applicable  Part 503 requirements are
likely to be issued to non-NPDES  facilities as  well. A
permit applicant who has not received a response from
EPA should continue to comply with the applicable pro-
visions of the Part 503 rule.

Certain  surface disposal sites with  unique site condi-
tions may apply for site-specific pollutant limits. These
sites would be issued site-specific permits.

7.3.1.3   Who Issues the Permit?

At the time this document was published, the permitting
authority for Part 503"was EPA. Thus, owner/operators
of a surface disposal site must apply to  EPA Regional
Offices, not the state, for a federal sewage sludge per-
mit.  This will remain the case until  the sewage sludge
management programs of individual  states are approved
by EPA (see Section 1.3). When a state has an EPA-ap-
proved sewage sludge management program, the per-
mitting authority will be the state; for states without an
EPA-approved program, EPA will remain the  permitting
authority. State laws regarding the  use  or disposal of
sewage sludge, including permit requirements, must be
complied with, even if the state program  has not  re-
ceived federal approval.  For  more  information  on per-
mits, contact the appropriate EPA  regional  sludge
coordinator (Appendix B).

 7.3.2   State and Local Permits

State and local regulations and permits are highly vari-
able from jurisdiction to  jurisdiction. State  and local
regulatory agencies  that  require submittals  might in-
clude:

• Solid waste management agencies

ซ Water quality control agencies

• Health departments

• Building departments

 • Health departments

 • Planning and/or zoning commissions

 • Board of county commissioners
                                                   93

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 In many jurisdictions more than  one state or local
 agency has authority over a surface disposal site. Also,
 in some jurisdictions, one agency has control over mon-
 ofills and dedicated surface disposal sites while another
 agency has control  over MSW landfills where sewage
 sludge is codisposed.

 Depending on  the  jurisdiction,  one or more permits
 might be required for a surface  disposal site. Typical
 permits on the state and local levels include:

 • Solid waste management permit.

 • Special use permit.

 • Zone change certification.

 * Sedimentation control permit for surface  runoff into
   water courses.

 • Highway department permit for entrances on  public
   roads and increased traffic volumes.

 • Construction permit for site preparation.

 • Building permit to construct buildings on the site.

 • Operation permit for ongoing surface disposal operation.

 • Mining  permit for excavations.

 • Fugitive dust permit.

 • Business permit for charging fees.

 • Closure permit.

 The reviewing agency may require  the submittal of in-
 formation on standard forms or in a prescribed format to
 facilitate the review  process. In  any event,  applicants
 are responsible for the completeness and accuracy of
 the application  package. The completed application
 package is then reviewed by the regulatory agency. The
 time of the review period will vary depending on the
 regulatory agency, the number of applications preceding
 it, etc. After a permit is issued, it can be valid for various
 durations, depending largely on the submittal of inspec-
 tion/performance reports and the outcome of onsite in-
 spections.

 7.4   Design  Methodology and  Data
      Compilation

 Adherence to a carefully planned sequence of activities
 to develop a design for a surface disposal site  minimizes
 project delays and expenditures. A checklist of design
 activities is presented in Table 7-1. These activities are
 listed generally in their order of performance; however,
 in many cases separate tasks can and should be per-
formed concurrently or even out of the order shown.

 Initial tasks in  any design methodology consist of com-
piling existing  information and generating new informa-
tion on sludge and site conditions. See Chapter 4, Siting,
 and Chapter 6, Field Investigation for extensive informa-
 tion on collecting existing and site-specific information
 for use in the design phase.

 A complete design package may include plans, specifi-
 cations, a design report, cost estimate, and operator's
 manual. Generally,  the cost estimate and  operator's
 manual  are  prepared strictly for in-house uses, while
 plans, specifications, and design reports are submitted
 to regulatory agencies in the permit application. Plans
 and specifications typically include:

 • Topographical  map showing existing site conditions.
   The map should  be of sufficient detail, with contour
   intervals of no  more than 5 ft (1.5 m) and a scale not
   to exceed 1 in. = 200 ft (1 cm = 24 m).

 • Soil map,  drainage map, and ground-water or pie-
   zometric contour map.

 • Site plan locating active sewage sludge units and soil
   stockpile areas as well as site buildings. A small-scale
   version of a site plan has been  included as Figure 7-2.

 • Development plan showing initial excavated and final
   completed contours in sludge filling  areas for mon-
   ofills or surface impoundments and lagoons.

 • Elevations  showing cross sections to illustrate phased
  development of filling areas at  several interim points.

 • Construction details illustrating detailed construction
  of site facilities.

 • Completed site plan including  final site landscaping,
  appurtenances, and other improvements.

 A design report typically includes:

 • Site description including existing site size, topogra-
  phy and slopes, surface water, utilities,  roads, struc-
  tures,  land use, soils,  ground water, bedrock, and
  climatology.

 • Design criteria  including sludge types and volumes,
  sludge transport methods, and fill or disposal area
  design dimensions.

• Operational procedures including site  preparation,
  sludge unloading,  sludge  handling, sludge storage,
  sludge disposal rates for dedicated surface disposal
  (DSD) sites, and sludge covering as well as equip-
  ment and personnel requirements.

• Information on  environmental  safeguards including
  surface water runoff controls, liners and leachate col-
  lection systems, gas controls, odor controls, and vec-
  tor reduction controls.
                                                   94

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Table 7-1.  Sewage Sludge Surface Disposal Site Design
           Checklist
Step
Task
Step
                                                                            Task
      _   Determine sludge volumes and characteristics
         •  Existing
         •  Projected
         Compile" existing and generate new site information
         •  Perform boundary and topographic survey
         •  Prepare base map of existing conditions on site and
            near site
            -  Property boundaries
            -  Topography and slopes
            -  Surface water
            -  Utilities
            -  Roads
            -  Structures
            -  Land use
         •  Compile hydrogeological information and prepare
            location map
            -  Soils (depth, texture, structure, bulk density,
              porosity, permeability, moisture, ease of excavation,
              stability, Ph, and cation exchange
            -  Bedrock (depth, type, presence of fractures,
              location of surface outcrops)
            -  Ground water (average depth, seasonal
              fluctuations, hydraulic gradient, and direction of
              flow, rate of flow, quality, uses)
         •  Compile climatological data
            -  Precipitation
            -  Evaporation
            -  Temperature
            -  Number of freezing days
            -  Wind direction
          •  Identify regulations (federal, state, and local) and
            design standards
            -  Requirements for sludge stabilization
            -  Sludge loading rates
            -  Frequency of  cover
            r  Distances to residences, roads, and surface water
            -  Monitoring
            -  Roads
            -  Building codes
            -  Contents of application for permit
          Design filling area
          • Select disposal method based on:
            - Sludge characteristics
            - Site topography and slopes
            - Site soils
                                                                  Design filling area (continued)
                                                                     -  Site bedrock
                                                                     -  Site ground  water
                                                                  •  Specify design dimensions
                                                                     -  Trench dimensions
                                                                     -  Area fill dimensions
                                                                     -  Surface impoundment and lagoon dimensions
                                                                     -  Area requirements for DSD
                                                                     -  Sludge fill depth
                                                                     -  Intermediate cover soil thickness
                                                                     -  Final cover soil thickness
                                                                  •  Specify operational features
                                                                     -  Use of bulking agent
                                                                     -  Type of bulking agent
                                                                     -  Bulking ratio
                                                                     -  Use of cover soil
                                                                     -  Method of cover application
                                                                     -  Need for imported soil
                                                                     -  Equipment requirements
                                                                     -  Personnel requirements
                                                                   •  Compute sludge and soil uses
                                                                     -  Sludge disposal rate
                                                                     -  Soil requirements
                                                                   Design facilities
                                                                   •  Leachate controls
                                                                   •  Gas controls
                                                                   •  Surface water controls
                                                                   •  Access roads
                                                                   •  Special working areas
                                                                   •  Structures
                                                                   •' Utilities
                                                                   •  Fencing
                                                                   •  Lighting
                                                                   •  Washracks
                                                                   •  Monitoring wells
                                                                   •  Landscaping
                                                                   Prepare design package
                                                                   •  Develop preliminary location plan of fill areas
                                                                   •  Develop contour plans
                                                                     -  Excavation  plans
                                                                     -  Completed  fill plans
                                                                95

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 Table 7-1.  Sewage Sludge Surface Disposal Site Design
           Checklist (continued)
 Stop    Task

 5       Prepare design package (continued)
         •  Compute sludge storage volume, soil requirement
           volumes, and site life
         •  Develop final location plan showing:
           - Normal fill areas and disposal areas
           - Special working areas
           - Leachate controls
           - Gas controls
           - Surface water controls
           - Access roads
           - Structures
           - Utilities
           - Fencing
           - Lighting
           - Washracks
           - Monitoring wells
           - Landscaping
        •  Prepare elevation plans for monofills and surface
           impoundments with cross sections of:
          - Excavated fill
          - Completed fill
          - Phased development of fill at interim points
        •  Prepare construction details
          - Leachate controls
          - Gas controls
          - Surface water controls
          - Access roads
          - Structures
          - Monitoring wells
        • Prepare cost estimate
        • Prepare design report
        • Submit application and obtain required permits
        • Prepare operator's manual

7.5   Design for Monofills, Surface
       Impoundments,  and Piles and
       Mounds
7.5.1   Foundation Design

The following discussion is geared primarily toward ac-
tive  sewage sludge units  that  are lined and  have
leachate collection systems; however, good engineering
practice requires that proper subsoil foundation design
of all surface disposal sites be adequately addressed
during the design phase.
 Proper subsoil foundation design of an active sewage
 sludge unit with  a liner is critical because liner system
 components, especially leachate collection pipes  and
 sumps, can be easily damaged by stresses caused by
 foundation movement.

 Good engineering guidance requires that foundations
 must be capable of providing support to the liner as well
 as resistance of pressure gradients above and below the
 liner to prevent  failure of the  liner due to settlement,
 compression, or  uplift.

 Foundations for monofills or surface impoundments and
 lagoons should provide structurally stable subgrades for
 the overlying components. The foundations also should
 provide satisfactory contact with the overlying liner or
 other system components. In addition, the foundation
 should resist settlement, compression, and uplift result-
 ing from internal or external pressures, thereby prevent-
 ing distortion or rupture of overlying components (U.S.
 EPA, 1988a).

 7.5.1.1   Field (investigation

 Adequate field investigations are  necessary to ensure
 that the  foundation design is developed to accommo-
 date expected site conditions.  Field investigations are
 designed to establish the in situ subsurface properties,
 site hydrogeologic characteristics,  and the area seismic
 potential, all of which are  critical to the design  of a
 surface disposal  site. Subsurface exploration programs
 are conducted to determine a site's in situ subsurface
 properties, as well as its geology and hydrogeology. The
 in situ subsurface properties and hydrogeologic charac-
 teristics have a significant influence on the bearing ca-
 pacity, settlement  potential,  slope stability,  and  uplift
 potential for the site. The site's subsurface geology may
 impact the settlement  and seismic potential at  the  site
 and exert an influence on the site's hydrogeology char-
 acteristics. See Chapter 6 for a more extensive discus-
 sion on field investigations and subsurface explorations
 programs.

 7.5.1.2  Foundation Description

 Foundation design procedures are site specific and very
 often are an iterative procedure. A typical preliminary
 foundation description should include (U.S. EPA, 1988a):
 • Geographic setting
 • Geologic setting

 • Ground-water conditions

 • Soil and rock properties

• Surface-water drainage conditions
• Seismic conditions

• Basis of information
                                                    96

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                     LEGEND


              	— EXISTING CONTOURS

              	PROPERTY BOUNDARY

              	 ROADS

              I I I II I" RAILROAD

              	T	 TRANSMISSION LINE

              	STREAM

              gf^  POND

                S   DWELLINGS

                •   PUBLIC BUILDINGS

                 •    WELL
       WOODS

       DISPOSAL AREA BOUNDARY

       GROUNDWATER MONITORING
        POINT

       SURFACE WATER MONITORING
        POINT
       SURFACE WATER DRAINAGE
        SYSTEM
       SILTATION BASIN
       GAS CONTROL/VENTING

IVM    OPERATIONAL FACILITIES

niMi/ma  DISPOSAL TRENCHES
Figure 7-2. Typical site plan.
Site plans should include the active sewage sludge unit
locations within the site; the unit depths, configurations,
and dimensions; and whether the unit will be completed
below or above grade. It is particularly important that the
investigation borings, test pits, and  other  procedures
described in Chapter 6 be performed as near as possi-
ble to the active sewage sludge units, if not within their
boundaries. Some other critical elements of the founda-
tion design that need to be addressed prior to comple-
tion of the field investigation are the foundation design
        alternatives, the foundation grade, the loads exerted by
        the unit or the foundation, and the preliminary settlement
        tolerances.

        7.5.1.3   Foundation Design

        The engineering analysis for foundations is  based on
        subsurface conditions;  however, the  results of such
        analyses are based on  loading conditions. To perform
        the appropriate engineering analysis to demonstrate the
                                                     97

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  loadings should be prepared, in addition to plans showing
  the structure's shape and size, the expected waste char-
  acteristics and volumes, and the foundation elevations.

  Foundations are designed to (U.S. EPA, 1988a):

  •  Provide structural support and to control settlement
  •  Prevent bearing capacity failure

  •  Withstand hydrostatic pressures

  These are all discussed below.

  Settlement and Compression

  The foundation should be capable of preventing failure
  of the liner system due to settlement and compression.
 Therefore, it is important that an analysis be carried out
  estimating total and differential settlement/compression
 expected due to the  maximum  design loadings. The
  results of this analysis are then used to evaluate the
 ability of the liner system as well as the leachate collec-
 tion and recovery systems  to maintain their integrity
 under the expected stresses (U.S. EPA, 1988a).

 A settlement analysis will provide an estimate of maxi-
 mum settlement. This maximum settlement can be used
 to aid in estimating the differential settlement and distor-
 tion of an active sewage sludge unit. Allowable settle-
 ment  is typically  expressed as  a  function  of  total
 settlement, rather than differential settlement, because
 the latter is much more difficult to predict; however, the
 differential settlement  is a more serious threat to the
 integrity of the structure than total settlement (Lambe
 and Whitman, 1969; Wahls, 1981).

 Active sewage sludge unit design calculations should
 include estimates of the expected settlement, even if it
 is expected to be small. Small amounts of settlement,
 even a few inches,  can  cause  serious  damage  to
 leachate collection piping or sumps.

 Bearing Capacity

 For active sewage sludge units, the major issue of con-
 cern for foundations is differential settlement; however,
 for structures such as leachate risers, an additional area
 of concern is bearing capacity failure (U.S. EPA, 1987a).

 The basic criterion for foundation design is that settle-
 ment must not exceed some permissible  value. This
 value varies,  dependent on the structure and the toler-
 ance for movement without disruption of the unit's integ-
 rity. To ensure that the basic criterion is met, the bearing
 capacity of a  soil, often termed its stability, is the ability
 of the soil to  carry a load without failure within the soil
 mass. The load carrying capacity of soil varies not only
with its strength, but often with the magnitude and dis-
tribution of the load. The reference Sowers and Sowers
 (1970) provides information regarding the evaluation of
bearing capacities and typical ranges of key parame-
 ters. After the bearing capacity is determined, the settle-
 ment under the expected  load conditions should  be
 estimated and compared to the permissible value. The
 foundation design should be such that the actual bearing
 stress is less than the bearing capacity by an appropri-
 ate factor of safety (U.S. EPA, 1987a; Winterkorn and
 Fang, 1975; Lambe and Whitman, 1969).

 Seepage and Hydrostatic Pressures

 Foundations should be designed to control seepage and
 hydrostatic pressures.  Heterogeneities such as  large
 cracks,  sand lenses,  or sand seams in the foundation
 soil offer pathways for leachate migration in the event of
 a release through the liner and could cause piping fail-
 ures. In addition, soft spots  in the foundation soils due
 to seepage can cause differential settlement possibly
 causing cracks in the liner  above and damaging any
 leachate collection or  detection system installed. Cracks
 also can be caused by hydrostatic pressure where the
 latter exceeds the confining  pressure of the foundation
 and liner (U.S.  EPA, 1986b).

 Solutions to these problems  include various systems
 that are available to  lower  the hydraulic head at the
 active sewage  sludge unit.  These systems include
 pumping wells, slurry  walls, and trenching. Other meth-
 ods to  control foundation seepage include grouting
 cracks and fissures in the foundation soil with bentonite
 and designing compacted clay cut-off seals  to be em-
 placed in areas of the foundation where lenses or seams
 of permeable soil occur (U.S. EPA, 1986b).

 7.5.2   Monofill Design

 Several monofills were identified and described in Chap-
 ter 2, Surface Disposal Practices. These include:

 •  Sludge-only trench
 -  — Narrow trench
   - Wide trench

 •  Sludge-only area fill
  - Area fill mound
  - Area fill layer
  - Diked containment

 Chapter  2 provides a detailed discussion on each of
 these monofills, and Table 2-1  lists the most significant
 features affecting monofill selection, which are:

 • Sludge percent solids.

 • Sludge characteristics (stabilized or unstabilized).

• Hydrogeology  (deep or shallow  ground water  and
  bedrock).

• Ground slopes.
                                                  98

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Having chosen a site (Chapter 4) and a monofill (Chap-
ter 2) appropriate to that site, a suitable design must be
established.  Sections 7.5.2.1 and 7.5.2.2 discuss con-
siderations that are relevant to trench and area fills. In
addition, Chapter  14,  Design Examples,  provides an
illustration of how a monofill is selected for a given site.

7.5.2.1  Trench Designs

In a trench operation, sludge is placed entirely below the
original ground surface. Sludge is usually dumped di-
rectly  into trenches from  haul vehicles. Onsite equip-
ment is used only to excavate trenches and apply cover;
equipment does not usually come into contact with the
sludge.
Trenches have been further classified  into  narrow
trenches and wide trenches. If trenches are selected,
design of the filling area consists primarily of determin-
ing the following parameters:

•  Excavation depth

•  Spacing

•  Width

•  Length
•  Orientation

•  Sludge fill depth  •

•  Cover thickness
Table 7-2 outlines  a methodology for determining each
of these parameters.
Trench spacing is  perhaps the most important and yet
most  difficult design parameter to determine. Trench
spacing is  defined as the width of solid  undisturbed
                                     ground that is maintained between adjacent trenches.
                                     Generally, trench spacing should be as small as possi-
                                     ble to optimize land utilization rates; however, the trench
                                     spacing must be sufficient to resist sidewall cave-in.
                                     Failure of the trench sidewalls is a safety hazard and
                                     reduces the volume of the trench available for disposal.
                                     Factors to consider in determining trench spacing include:

                                     • The weight of the excavating machinery.

                                     • The bearing capacity of the soil (which is a factor of
                                       soil  cohesion, density, and  compaction).

                                     • Saturation level of the soil (which may be significantly
                                       influenced  by the moisture  content of the sludge).

                                     • The depth  of the trench.

                                     • Soil stockpiling and cover placement procedure.

                                     A general rule of thumb to follow in establishing trench
                                     spacing is that for every 1  ft (0.3 m) of trench depth,
                                     there  should be 1 to 1.5 ft  (0.3  to 0.5 m) of space
                                     between trenches. If  large inter-trench spaces are not
                                     practical, the problem of sidewall instability may be re-
                                     lieved by utilizing  one of the  four trench sidewall vari-
                                     ations  shown in Figure  7-3. In  any  event, test cell
                                     trenches should be used to determine the operational
                                     feasibility of  any trench design. Such  tests  should  be
                                     performed by excavating adjacent trenches to the speci-
                                     fied depth,  width,  and  spacing. A haul vehicle fully
                                     loaded with sludge should then back up to the trench to
                                     determine if the sidewall stability is sufficient.
                                     Using the considerations included in Table 7-2, design
                                     parameters can be determined for a variety of sludge
                                     and site conditions. These considerations have  been
                                     employed to develop some alternative design scenarios
                                     for trenches shown in Table 7-3. In some cases, sludge
 Table 7-2. Design Considerations for Trenches

 Design Parameter    Determining Factor
                              Consideration
 Excavation Depth
Depth to groundwater
Depth to bedrock
Soil Permeability
Cation exchange capacity of soil

Equipment limitations
                    Sidewall stability
Sufficient thickness of soil must be maintained between trench bottom and
groundwater or bedrock Required minimum separation varies from 2 to 5 ft.
Larger separations may be required for higher than normal soil permeabilities
or sludge loading rates.
Normal excavating equipment can excavate efficiently to depths of 10 ft.
Depths from 10 to 20 ft are less efficient operations for normal equipment;
larger equipment may be required. Depths over 20 ft are not usually possible.

Sidewall stability determines maximum depth of trench. If haul vehicles are
to dump sludge into trench from above, straight sidewall should be
employed. Tests should be performed at site with a loaded haul vehicle to
ensure that sidewall height as designed will not collapse under operating
conditions.
 Spacing
Sidewall stability
                    Soil stockpiles
                    Vehicle access
Trench spacing is determined by sidewall stability. Greater trench spacing will
be required when additional sidewall stability is required. As a general rule,
1.0 to 1.5 ft of spacing should be allowed between trenches for every 1 ft of
trench depth.
Sufficient space should be maintained between trenches for placement of
trench soil stockpiled for cover as well as to allow access and free
movement by haul vehicles and operating equipment.
                                                       99

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 Tablo 7-2.  Design Considerations for Trenches (continued)

 Design Parameter     Determining Factor               Consideration
 Width
Sludge solids content
                      Equipment limitations
                      Equipment efficiencies
 Length
Sludge solids content
Ground slopes
Widths of 2 to 3 ft for typical sludge with solids content from 15 to 20%.
Widths of more than 3 ft for typical sludge with solids content more than
20%. Certain sludge (e.g., polymer treated) may require higher solids
contents before these widths can apply.

Widths up to 10 ft for typical equipment (such as front end loader) based on
solid ground alongside trench. Widths up to 40 ft for some equipment (such
as a dragline) based on solid ground. Unlimited widths for cover applied by
equipment (such as bulldozers) which proceed out over sludge.
                                Equipment
                           Typical Widths
Trenching machine
Backhoe
Excavator
Track dozer
Track loader
Dragline
Scraper
2ft
2-6 ft
4-22 ft
>10ft
i10ft
;>40 ft
>20ft
If sludge solids are low and/or trench bottoms not level, trench should be
discontinued or dikes placed inside trench to contain sludge in one area and
prevent it from flowing over large area.
 Orientation
Land availability

Ground slopes
                                                     Trenches should be parallel to optimize land utilization.

                                                     For low solids sludge, axis of each trench should be parallel to topographic
                                                     contours to maintain constant bottom elevation within each trench and
                                                     prevent sludge from flowing. With higher solids sludge, this requirement is
                                                     not necessary.
Sludge fill depth Trench width
Cover application method
Cover thickness Trench width
Cover application method
Trench width
2-3 ft
>3ft
>10ft
Trench width
2-3 ft
>3ft
>10ft
Cover application method
Land-based equipment
Land-based equipment
Sludge-based equipment
Cover application method
Land-based equipment
Land-based equipment
Sludge-based equipment
Minimum distance
from top
1-2 ft
3ft
4ft
Cover thickness
2-3 ft
3-4 ft
4-5 ft
              TYPE  I                    TYPE  2

Figure 7-3.  Trench stdewall variations.


and site conditions may indicate that it is wholly appro-
priate to  utilize one of these trench scenarios for appli-
cation to a real-world situation.  Given the great variety
of sludge and site conditions and their combinations,
however, some adaptation of one of these scenarios will
                                             TYPE  3
                                             TYPE 4
                                        be necessary in most cases. In  any event, design pa-
                                        rameters  should  not be merely extracted from  these
                                        tables; parameters should always  be well-considered
                                        and tested before full-scale application. An example of
                                        a trench design (which utilizes these tables initially, fol-
                                                          100

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                                                          101

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  lowed by engineering investigation and field testing) has
  been included in Chapter 14, Design Examples.

  Narrow Trench

  The use of narrow trenches has grown considerably
  despite high area requirements (U.S. EPA, 1986a). This
  method has found much more  acceptance than other
  forms of monofilling in areas where  siting of a conven-
  tional MSW landfill or a wide-trench monofill would en-
  counter community resistance (U.S. EPA, 1986a). One
  of the very important advantages of narrow trench mon-
  ofilling is that the time during which sludge is uncovered
  can be reduced to  minutes with subsequent minimal
  likelihood of unpleasant odors.

  Narrow trenches have widths less than 10 ft (3.0 m) and
  usually receive sludge with solids contents as low as
  15%. Excavation and cover application in narrow trench
 operations  is carried out via equipment operating on
 solid ground alongside the trench. Illustrations of typical
 narrow trench  operations are included as Figures 7-4
 and 7-5. See also Section 2.3.1.1 for detailed informa-
 tion on narrow trenches.  Sludge characteristics, site
 conditions, and design criteria for narrow trenches are
 summarized in Tables 2-1 and 2-2.

 The method of sludge placement in a narrow trench is
 dependent on the type of haul  vehicle and on trench
 sidewall  stability. Usually trench sidewalls are  suffi-
 ciently stable and sludge may be dumped from the haul
 vehicle directly into trenches. If sidewalls are not suffi-
 ciently stable, however, the sludge may be delivered to
 the trench in a chute-extension similar to  that found on
 concrete trucks or pumped in via portable  pumps. In
 some cases, particularly in wet weather, it may be nec-
 essary  to dump the sludge on  solid ground near the
 Figure 7-5. Cross section of typical wide trench operation.

 trench and have onsite equipment push the sludge into
 the trench.

 Wide Trench

 Wide trenches  have widths greater than  10 ft (3.0 m)
 and usually receive sludge with solids contents of 20%
 and more. Excavation of wide trenches is usually carried
 out using equipment that enters the trench. Cover appli-
 cation may be carried out using equipment operating on
 solid ground alongside the trench, but is usually accom-
 plished  with equipment that  traverses  the  sludge
 spreading a layer of cover soil before it. Illustrations of
typical wide trench operations are included as Figures
7-6 and 7-7. See also Section 2.3.1.2 for detailed infor-
 mation on wide trenches.  Sludge characteristics,  site
conditions, and design criteria  for wide trenches  are
summarized in Tables 2-1 and 2-2.

Sludge may be placed in wide trenches by haul vehi-
cles, either:
Figure 7-4.  Cross section of typical narrow trench operation.
                                                  102

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          EXCAVATED
            DEPTH
               61
Figure 7-6.  Cross section of typical wide trench operation.
Figure 7-7.  Wide trench operation.

•  Directly entering the trench and dumping sludge in 3
   to 4 ft (0.9 to 1.2 m) high piles.

•  Parked at the top of trench sidewalls and  dumping
   sludge into the trench.

For the first of these two cases, sludge should have a
solids content of 32% or more to ensure that the sludge
will not slump and can be maintained in piles. For the
second approach, sludge should have a solids content
less than 32% to ensure that it will flow evenly through-
out the trench and not accumulate at the dumping loca-
tion.  Of course,  when sludge  is freeflowing, some
means will be needed to confine the  sludge to specific
areas in a continuous trench. Dikes are often used for
this purpose as illustrated in Figure 7-8.

 7.5.2.2  Area Fill Designs

 In an area fill operation, sludge is usually placed entirely
 above the  original ground surface. The sludge as re-
 ceived is usually mixed with soil to increase its effective
 solids content and stability. Several consecutive lifts of
 this sludge/soil mixture are usually then applied to the
filling area.  Soil may be applied for interim cover in
addition to its usual application for final cover. Onsite
equipment .usually  does  come into contact with the
sludge while performing functions of mixing the sludge
with soil; transporting this mixture to the fill area; mound-
ing or layering this  mixture; and spreading cover over
the mixture.

Area fills have been further  classified into  area fill
mounds, area fill layers, and diked containments. If one
of these landfilling methods has been selected, design
of the filling area may consist  primarily of determining
the following parameters:

•  Bulking ratio

•  Cover application procedure

•  Width (of diked containment)

•  Depth of each lift

•  Interim cover thickness

•  Number of lifts

•  Depth of total fill (or diked containment before final cover)

•  Final cover thickness

Table 7-4 outlines a methodology for determining each
of these parameters.

 Using the considerations included in Table 7-4, the de-
 sign parameters can be  determined for a variety of
sludge and site conditions. These considerations have
 been employed to develop some alternative design sce-
 narios  for area fills that are included in Table 7-3. An
 example of an area fill design (which utilizes  these
 tables initially, followed by investigation  and testing) has
 been included in Chapter 14, Design Examples.
                                                    103

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           DEPTH
Figure 7-8.  Cross section of wide trench with dikes.

Table 7-4.  Design Considerations for Area Fills
Design Parameter
                                                                     Consideration

Bulking Ratio










Cover Application
Procedure





Width
(of diked containment)

Depth of each (in




Method
Area fill mound


Area fill layer



Diked containment


Method
Area fill mound
Area fill layer
Diked containment

Cover Application
Procedure
Land-based equipment
Sludge-based equipment
Method
Area fill mound
Area fill layer

Diked containment

Solids Content
20-28%
28-32%
ฃ32%
15-20%
20-28%
28-32%
> 32%
20-28%
28-32%
> 32%
Solids Content
> 20%
2. 15%
20-28%
> 28%

Equipment Used
Dragline
Track dozer
Sludge Solids
> 20%
15-20%
> 20%
20-28%
> 28%
Bulking Ration
2 soil:1 sludge
1 soil:1 sludge
0.5 soil:1 sludge
1 soil:1 sludge
0.5 soil:1 sludge
0.25 soil:1 sludge
Not required
0.5 soil:1 sludge
0.25 soil:1 sludge
Not required
Cover Application
Procedure
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment

Width
<;40ft
Not limited
Lift Depth
6ft
1 ft
2-3 ft
4-6 ft
6-10 ft
                                                         104

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Table 7-4. Design Considerations for Area Fills (continued)
                                                             Consideration
Interim cover thickness



Number of lifts


Depth of total fill
(of diked containment
before final cover)
Final cover thickness



Method
Area fill mound
Area fill layer
Diked containment

Method
Area fill mound
Area fill layer
Diked containment
Cover Application Procedure
Land-based equipment
Sludge-based equipment
Method
Area fill mound
Area fill layer
Diked containment

Cover Application
Procedure
Sludge-based equipment
Sludge-based equipment
Land-based equipment
Sludge-based equipment
Sludge Solids Contents
20-28%
>28%
> 15%
> 20%

r
Cover Application
Procedure
Sludge-based equipment
Sludge-based"equipment
Land-based equipment
Sludge-based equipment
Interim Cover
Thickness
3ft
0.5-1 ft
1-2 ft
2-3 ft
No. of Lifts
1 maximum
3 maximum
1-3 typical
1-3 typical
Depth of Total Fill
No higher than 3 ft
below top of dikes
No higher than 4 ft
below top of dikes
Final Cover Thickness
1 ft
1 ft-
3-4 ft
4-5 ft
 Area Fill Mound

 At area fill mound operations, sludge/soil mixtures are
 stacked  into mounds approximately 6 ft (1.8 m) high.
 Cover soil is applied atop each lift of mounds in a 3 ft
 (0.9 m)  thickness. The cover thickness may  be  in-
 creased  to 5 ft (1.5 m) if additional mounds are applied
 atop the first lift. Illustrations of typical mound  opera-
 tions are included as  Figures 7-9 and 7-10. See also
 Section  2.3.2.1  for detailed  information on  area fill
 mounds. Sludge characteristics, site conditions, and de-
 sign criteria for area  fill  mounds are summarized  in
 Tables 2-1 and 2-2.

 Sludge as received at the landfill is  usually mixed with
 a bulking agent.  The  bulking agent absorbs excess
 moisture from the sludge and increases its workability.
 The amount of  soil needed to serve as an additional
 bulking  agent depends on the solids content  of the
 sludge. Generally the soil requirements shown in Table
 7-4 may serve as a guideline. Fine sand appears to be
 the most suitable bulking agent because it can most
 easily absorb the excess moisture from the sludge.
Area Fill Layer

At area fill layer operations, sludge/soil mixtures are
spread evenly in layers from 0.5 to 3 ft (0.15 to 0.9 m)
thick. This layering usually continues for a number of
applications. Interim cover between consecutive layers
may be  applied in 0.5 to 1 ft (0.15 to 0.3 m) thick
applications. Final cover should be at least 1 ft (0.3 m)
thick. An illustration of a typical area fill layer operation
is included as Figure 7-11. See also Section 2.3.2.2 for
detailed information on area fill layers. Sludge charac-
teristics, site conditions, and design criteria for area fill
layers are summarized in  Tables 2-1 and 2-2.

Diked Containment

At diked containment operations, earthen dikes are con-
structed to form a containment area above the original
ground surface. Dikes can be of various  heights,  but
require side slopes of at least 2:1 and possibly 3:1. A15
ft (4.6 m) wide road, covered with gravel, should be
constructed atop the dikes. An illustration of a typical
diked containment operation is included as Figure 7-12.
See also Section  2.3.2.3 for  detailed  information on
                                                     105

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                                    FINAL COVER
                                                            REMOVE FOR USE
                                                            AS SLUDGE BULKING
                                                            AGENT
                         FUTURE
                         DRAINAGE
                         DITCH
                  INTERMEDIATE COVER
                        <3' THICK)
                                LEACHATE CONTROL


 Figure 7-9.  Cross section of typical area fill mound operation.
SLUDGE/SOIL
  MIXTURE
 Figure 7-10.  Area fill mound operation.
                                                                 REMOVE FOR USE
                                                                 AS SLUDGE BULKING
                                                                 AGENT
                                            INTERIM COVER
                                            (0.5-I THICK).
                    LEACHATE COLLECTION


Figure 7-11.  Cross section of typical area fill layer operation.
                                                                                  FUTURE
                                                                                  DRAINAGE
                                                                                  DITCH
           SLUDGE/SOIL MIXTURE
               (3' THICK)
                                                      106

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                       MIN. OF 15' OR AS REOUSRED
                       FOR CONSTRUCTION EQUIPMENT
              EXTEND TO PREVENT
              DISCHARGE ON SLOPE
              FACE
                             3
                 UPPER SLUDGE LAYER
               MIDDLE DRAINAGE BLANKET
Figure 7-12.  Cross section of typical diked containment operation.

diked containment. Sludge  characteristics, site condi-
tions, and design criteria for diked containments are
summarized in Tables 2-1 and 2-2.

Sludge may be either:

• Mixed with soil bulking for subsequent transport and
  dumping into the containment area by onsite equip-
  ment.
• Dumped directly into the containment area by haul
  vehicles without bulking soil.

Large quantities of imported soil may be required to
meet soil requirements for dike construction and bulking
since diked  containments are often constructed in high
ground-water areas.                            ' ,
Sludge is dumped into diked containments in lifts before
the application of interim cover. Often this interim cover
is a highly permeable drainage blanket that acts as a
leachate collection system for sludge moisture released
from the sludge lift above.  Final cover should be of a
less-permeable nature  and should be graded even with
the top of the dikes.
 7.5.3  Surface Impoundment and Lagoon
        Design
 At aboveground surface impoundments, dikes are used
 to contain the sewage sludge, and haul vehicles dump
 sludge directly into the containment area from the sides
 of the dikes. Design information for diked containment
 can be found in Section 7.5.2.2.
 Belowground surface impoundments or lagoons have
 been widely used for treatment and storage of sludge.
 The surface disposal provisions of the Part 503  rule do
 not apply when sludge is treated in a lagoon (or other-
 wise treated on the land) for what could be an indefinite
 period. Figure 7-13 compares treatment lagoons and
 storage/disposal  lagoons. The surface disposal provi-
 sions also do not apply to lagoons used for long-term
 temporary storage of sludge ifthe storage is considered
part  of  the  treatment process  and if the facility's
owner/operator has a rationale or a plan for final use or
disposal of the sludge. If, however, the sludge generator
has no intention of ever removing the sludge from the
lagoon, the facility is considered a surface disposal site
and is subject to the Part 503 surface disposal require-
ments, including requirements for pollutant limits, clo-
sure,  management practices,  pathogen  and  vector
attraction reduction, monitoring, and recordkeeping and
reporting.  Many states also  have requirements for la-
goons. Check with your state  for any  specific  state
requirements for designing lagoons.

Ground-water protection is a key concern with respect
to sludge  lagoons, A minimum soil buffer of 4 ft is rec-
ommended between the bottom of  a lagoon and the
seasonal  annual high ground-water table. Liners and
leachate collection systems  should be considered, de-
pending on  sludge quality, distance  to drinking water
wells, depth to ground water, ground-water flow direc-
tion and velocity, aquifer classification,  and underlying
soil type and permeability (U.S. EPA, 1990).
Three types of lagoons are described below: facultative
sludge lagoons, anaerobic liquid  sludge lagoons, and
sludge drying lagoons. If the dewatered sludge is peri-
odically removed from these lagoons, they are consid-
ered  treatment lagoons,  but if the sludge is  never
removed,  they are considered surface disposal facilities.

7.5.3.1    Facultative Sludge Lagoons

Facultative  sludge lagoons (FSLs)  are designed  to
maintain an aerobic surface  layer free of scum or  mem-
brane-type film buildup. The aerobic layer is maintained
by keeping the annual organic loading to the lagoon at
or below a critical area loading rate and by using surface
 mixers  to provide agitation  and mixing  of the aerobic
surface layer. The aerobic surface layer of  FSLs is usu-
ally from 1 to 3 ft (0.30 to 0.91 m) in depth and supports
 a very dense population of  between 50 x 103 and 6 x
 106 organisms/mL of algae (usually Chorella). Dissolved
                                                   107

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    a)  Wastawater
        Treatment
         Lagoon
                                              Settled Sludge •

                      Initial Treatment Lagoon                        Polishing Pond
                                                                                      Effluent
                               Settled Sludge
    b)   Sludge
       Storage/
       Disposal
       Lagoon
                                                                                       Sludge Lagoon
 Figure 7-13.  Comparison of wastewater lagoon and sludge lagoon (U.S. EPA, 1990).
 oxygen is supplied to this layer by algal photosynthesis,
 by direct surface transfer from the atmosphere, and by
 the surface mixers. The oxygen  is used by the bacteria
 in the aerobic degradation of colloidal and soluble or-
 ganic matter in the digested sludge liquor,  while the
 digested sludge solids settle to the bottom of the basins
 and continue their anaerobic decomposition. Sludge liq-
 uor or supernatant is periodically returned to the plant's
 liquid process stream.

 The nutrient and carbon dioxide released in both the
 aerobic and anaerobic degradation of the remaining
 organic matter within the digested sludge are,  in turn,
 used by the algae in the cyclic-symbiotic relationship.
 This vigorous relationship maintains the pH of the FSL
 surface layer at between 7.5 and 8.5, which effectively
 minimizes  any hydrogen sulfide (H2S) release and is
 believed to be a key to the successful operation of this
 type of sludge storage process.


 Facultative sludge lagoons must operate in conjunction
 with anaerobic digesters (U.S. EPA, 1979). They cannot
 function properly (without major environmental impacts)
 when supplied with  either unstabilized or aerobically
 digested sludge (U.S. EPA, 1979). If the acid phase of
 anaerobic stabilization becomes predominant,  the la-
 goons will give off an offensive odor. Figure 7-14 pro-
vides a schematic representation of the reactions in a
typical FSL.
 Design Criteria

 Design considerations for the  FSLs include the area
 loading rate,  surface  agitation requirements, dimen-
 sional and layout limitations, and physical factors:

 • Area Loading Rate. To maintain an aerobic top layer,
  the annual organic loading rate to the FSL must be
  at or below 20  Ib of volatile solids (VS) per 1,000 sq
  ft per day (1.0 t VS/ha-d). Lagoons have been  found
  to be capable of receiving the equivalent of the daily
  organic loading rate every second, third, or fourth day
  without experiencing any upset. That is, lagoons have
  assimilated up to four times normal daily loadings as
  long as they have had 3 days of rest between load-
  ings. Loadings  as high as 40 Ib VS  per 1,000 sq ft
  per day (1.0 t VS/ha-d) have been successfully as-
  similated for several months  during the warm  sum-
  mer and fall. Experiments on  small basins loaded to
  failure indicate that peak loadings up  to 90 Ib VS per
  1,000 sq ft per day (4.4 t VS/ha-d) can be tolerated
  during the summer and fall as long  as they do not
  occur for more than 1 week.

• Surface  Agitation Requirements.  Experiments on
  FSLs that were continuously  loaded at the standard
  rate (1.0 t VS/ha-d) indicate FSLs cannot function in
  an environmentally acceptable manner without daily
  operation  of surface agitation equipment.  Observa-
  tions indicate the brush-type mixer  is  required to
  breakup the surface film that forms during the feeding
                                                   108

-------
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Figure 7-14.  Schematic representation of an FSL (U.S. EPA, 1979),

  of the lagoon. If this film is not dissipated, a major
  source of oxygen transfer to the surface layer is elimi-
  nated. FSLs with surface areas of from 4 to 7 acres
  (1.6 to 2.8 ha) require the operation of two surface
  mixers from 6 to 12  hr per day to successfully main-
  tain scum-free surface conditions. All of the success-
  ful installations to date have used brush-type floating
  surface mixers to achieve the necessary surface agi-
  tation. Two brush-type mixers with  8-ft-long (2.4-m)
  rotors turning at approximately 70 rpm and driven by
  15 hp (11.2 kW) motors are required for a 4 to 7 acre
  (1.6 to 2.8 ha) lagoon. The mixers  need to operate
  12 hr per day. Lagoons  of much less than 4 acres
  (1.62 ha) should be  able to achieve the same results
  with two mixers with 6-ft  (1.8-m) long rotors and 5-hp
  (3.7  kW) motors. Operation time is expected to be
  about the same number of hours per day. Brush-type
  mixers have been used  to limit the agitation to the
  surface layer of the FSLs. So far this has  been an
  acceptable application; however, there is some ques-
  tion  as  to  their  applicability for very  cold climates.
  Several submerged  pump-type floating aerators have
  been reviewed, and  they could be adapted to provide
  the  necessary surface  agitation if the  brush-type
  could not function under severe freezing conditions.
                                             Two  mixers are used per FSL to ensure maximum
                                             scum breakup in those areas of the lagoon where the
                                             prevailing wind deposits the daily loading of scum. The
                                             agitation and mixing action of the two mixers located
                                             at opposite ends or sides of the lagoon also  act to
                                             maintain equal distribution of the anaerobic solids.

                                             Dimensional and Layout Limitations. The maximum
                                             area for a single lagoon area is somewhat arbitrary
                                             but is based on the most practical size for loading,
                                             surface agitation, mixing (and, for treatment lagoons,
                                             removal)  requirements. Large, 4 to 7 acre (1.6-2.8
                                             ha) individual lagoons would  be applicable only to
                                             plants with over 70 acres (28 ha) of FSLs. FSLs as
                                             small as 150 ft (45.7 m) on a side have been operated
                                             successfully. Lagoon  depths can range from about
                                             11.5 to 15,ft (3.5 to 4.7 m). If surface agitation must
                                             be maintained  by submerged pump type aerators, it
                                             may be necessary to use the deepest lagoon possible
                                             to ensure adequate separation between the aerobic zone
                                             and the anaerobic settling zone of the FSL.

                                             FSLs are usually best designed to have a long and
                                             a  short dimension, with the shortest dimension ori-
                                             ented parallel to the direction of the maximum pre-
                                             vailing  wind. The longer side is made conducive to
                                                  109

-------
   efficient dredge operation, while the short side's par-
   allel orientation to the prevailing wind direction helps
   to minimize wave erosion on the surrounding levees.
   Figure 7-15a is a typical FSL layout,  while Figure
   7-15b is a typical FSL cross section.
   When the area of FSLs exceeds 40 acres (16.2 ha),
   the potential cumulative effect of large odor emission
   areas to the vicinity must be considered. Figure 7-16
   shows the layout for the 124 acres (50.2 ha) of FSLs
   in Sacramento, California, that were sited on the ba-
   sis of the least odor risk to surrounding areas.  Bat-
   teries of FSLs totaling 50 to 60 acres (20 to 24 ha)
                                                    are about the maximum size for most effectively re-
                                                    ducing the transport of odors.

                                                    Physical Considerations. Many of the detailed physi-
                                                    cal considerations applied to the final design of the
                                                    Sacramento  FSLs are shown in Figures 7-15b and
                                                    7-16. Supernatant  withdrawal is located  upstream
                                                    from the prevailing  winds to minimize scum  buildup
                                                    in its vicinity.  FSL supernatant will precipitate magne-
                                                    sium ammonia phosphate (struvite) on any rough sur-
                                                    face that is not completely  submerged; it has also
                                                    been found to precipitate inside cavitating  pumps.
                                                    This crystalline material can completely clog cast-iron
                                                             PREVAILING WIND DIRECTION
                 SUPERNATANT
                 OVERFLOW
                           AUTOMATIC
                           CONTROL VALVE
                                            •SLUDGE REMOVAL
                                             VALVES
                                                     DIGESTED SLUDGE\
                                                     LINE*
                                                   -DIGESTED SLUDGE
                                                    INLETS	
                         SURFACE MIXER
                                                               SURFACE MIXER
                                                                                         SLUDGE
                                                                                         REMOVAL
                                                                                         DREDGE
                                                                                         ANCHOR
                                                                                         POSTS
                                                                                         (TYP)
                                                                                         BOTH
                                                                                  p

                                                                                   O  ENDS

                                                                                   •'p

                                                                                    c

                                                                                   1C
Figure 7-15a.  Typical  FSL layout (U.S. EPA, 1979).
                   3'0" AEROBIC LAYER
             12'0" ANAEROBIC   6" IMPERVIOUS
                     LAYER   LAYER
DIGESTED SLUDGE
      INLET
                                                                            PROTECTION
                                                                                  ENGINEERED FILL
                                                                        8" DIGESTED
                                                                        SLUDGE LINE
                                                SLOPE  3
                                                    1
                                                    -MINIMUM
                                                     2'S" COVER
                                                                -NATURAL
                                                                 GRADE
    1 ft - Q.3 m                        NOT TO SCALE
    1 Jn - 2.5 cm


Figure 7-15b.  Typical FSL cross section (U.S. EPA, 1979).
                                                  110

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                                                              MB I
                                                               iSlhliii!  i
                                                                 i
                              LAYOUT FOR 124 ACRES OF FSLs—SACRAMENTO    }

                               REGIONAL WASTEWATER TREATMENT PLANT
Figure 7-16.  Layout for 124 acres of FSLs: Sacramento Regional Wastewater Treatment Plant (U.S. EPA, 1979).
                                             111

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  fittings and  pump valves  when the surface goes
  through a fill-and-draw cycle or when its operation
  results in the presence of diffused air. The most prac-
  tical approach to eliminating this problem has been
  to use PVC piping throughout the FSL supernatant
  process and to design the process for gravity return
  to the plant influent, with  a minimum of critical depth
  conditions. If pumping is  required,  submerged slow-
  speed  nonclog centrifugal  pumps with  low suction
  and discharge velocities  (to minimize cavitation) will
  be the most trouble  free. All equipment that is not
  PVC or another smooth non-metallic material should
  be coated with a smooth, impervious surface.

Two digested sludge feed lines, each with its own auto-
matic valve, ensure adequate distribution of solids over
the whole volume of the FSL. Surface mixers are down-
stream of the prevailing winds. The harvested sludge
dredge hookup is centrally located. Lagoon dike slopes
are conservative—3 horizontal to 1 vertical—with ade-
quate rip-rap provided in the working zone of the surface
level. Sufficient freeboard is provided to protect against
any conceivable overtopping of the  dikes.  Digested
sludge feed pipelines  are  located directly below the
bottom of the lagoons, with the inlet surrounded by a
protective concrete surface. All piping within the basin is
out of the way of any future dredging operations.

Table 7-5 presents design criteria for the Sacramento,
California, facultative sludge lagoons.

7.5.3.2  Anaerobic Liquid Sludge Lagoons

An anaerobic lagoon is usually an open structure similar
to the facultative lagoon, but often with  a greater depth
in relation to surface area (Lue-Hing et al., 1992). These
lagoons settle solids with higher specific  gravity than
water and provide for  sludge storage  on  the bottom.
Unlike the facultative lagoon, an aerobic surface layer is

Tablo 7-5.  Design Criteria  for Sludge Storage Basins:
          Sacramento (California) Regional Wastewater
          Treatment Plant (Lue-Hing et al., 1992)

Total number of sludge storage basins                20
Surface area—hectares (acres)                  50.6 (125
Depth at normal operation—m (ft)                 4.57 (15)
Solids loading rate— kg/m2/d (lbs/1000 ffrd)       0.0975 (20)
Stored solids concentration. %                     >6
Surface mixers for aeration                         40
Barrier wall height, m (ft)                       3.64 (12)
Supernatant return flow metering                 3.154-17.0
  90ฐ V-notch weir, L/s (gpm)                    (50-270)
30.5 cm (12 in.) Parshall flume                  8.77-175.3
  L/s (MOD)                                 0.2-4.0)
not maintained and floatable material is not settled or
removed; thus, a thick scum layer can develop on the
lagoon surface. Sludge loading rates to anaerobic la-
goons are higher than the loading rates of facultative
lagoons (Lue-Hing et al., 1992). Figure 7-17 shows the
layout of four  anaerobic  lagoons at the Metropolitan
Sanitary District of Greater Chicago Prairie  Plan  land
reclamation project in Fulton County, Illinois.

Table 7-6 presents the advantages and limitations of
facultative sludge lagoons and anaerobic lagoons.
7.5.3.3   Sludge Drying Lagoons

Sludge drying lagoons consist of retaining walls that are
normally earthen dikes 2 to 4 ft (0.7 to 1.4 m) high. The
earthen dikes usually enclose a rectangular space with
a permeable surface. Appurtenant equipment includes
sludge feed lines and metering  pumps, supernatant de-
cant lines, and some type of mechanical sludge removal
equipment, if sludge is to be removed. In areas where
permeable soils are unavailable, underdrains and asso-
ciated piping may be required.

Figure 7-18 shows a plan view of a sludge drying lagoon.
                  3 a   TRANSFER I PUMP
                54.9 AC         , -K     3b

                                    37.3 AC
                                       HOLDING BASINS
      t acn - 0.4(15 h*
Figure 7-17.  Anaerobic liquid sludge lagoons, Prairie Plan land
           reclamation project, the Metropolitan Sanitary Dis-
           trict of Greater Chicago (U.S. EPA, 1979).
                                                    112

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Design Criteria
Proper design of sludge drying lagoons requires a con-
sideration of the following factors: climate, subsoil per-
meability, sludge characteristics, and lagoon depth and
area. A discussion of these factors follows.
 • Climate. After dewatering by drainage and supernat-
   ing, drying in a sludge lagoon depends primarily on
   evaporation. Proper size of a lagoon, therefore,  re-
   quires climatic information concerning:
   - Precipitation rate (annual and seasonal distribution).
Table 7-6.  Advantages and Limitations of Faculative Sludge Lagoons and Anaerobic Lagoons (U.S. EPA, 1979)
                      Advantages
                                                                   Limitations
    Provides long-term storage with  .
      acceptable environmental impacts
      (odor and groundwater contamination
      risks are minimized) .

    Continues anaerobic stabilization, with  up
      to 45 percent  VS reduction in first  year.

    Decanting ability assures minimum solids
      recycle with supernatant (usually  less
      than 500 mg/1)  and maximum concentration
      for storage and efficient harvesting
      (>6 percent solids)  starting with  digested
      sludge of <2 percent solids.

    Long-term liquid storage is one of few
      natural  (no external energy input) means
      of reducing pathogen content of sludges.

    Energy and operational effort requirements
      are very minimum.

    Once established, buffering capacity is
      almost impossible to upset.

    Allows for all  tributary digesters to
      operate as primary complete-mix units
      (one blending  unit may be. required for
      large installations).

    Provides environmentally acceptable  place
      for disposal of digester contents  during
      periodic cleaning operations.

    Sludge harvesting is completely independent
      from sludge  production.
    Can only be  used following anaerobic
      stabilization.  If acid phase of
      digestion  takes place in lagoons'  they
      will stink.

    Large acreages  require special odor .
      mitigation measures.

    Reauires large  areas of land, for
      example,  15 to 20 gross acres  (6  ro
      8 ha) for  10  MGD, (438 1/s) 200
      gross acres  (80 ha)  for 136 MGD
      (6,000 1)  carbonaceous activated
      sludge plants.

4.  Must be protected from flooding.

5.  Supernatant, will contain 300-600 mg/1
      of TKN, mostly ammonia.

6.  Magnesium ammonia phosphate  (struvite)
      deposition requires special supernat-
      ant design.
                                                                 @ DRAW - OFF BOX & TRUSS

                                                                 
-------
   — Evaporation rate (annual average, range, and sea-
     sonal fluctuations).
   - Temperature extremes.

 • Subsoil Permeability. The subsoil should have a mod-
   erate permeability of 1.6 x 10"4 to 5.5 x 10'4 in. per
   second (4.2 x 1CT4 to 1.4 x 10'3 cm/s).

 • Sludge  Characteristics. The  type of sludge to be
   placed in the lagoon can significantly affect  the
   amount  and type of odor and vector problems that
   can be produced. It is recommended that only an-
   aerobically digested sludges be used in drying lagoons.

 • Lagoon Depth and Area. The actual depth and area
   requirements  for sludge  drying lagoons depend on
   several faptors such as precipitation,  evaporation,
   type of sludge, volume and solids concentration. Sol-
   ids loading criteria have been given as 2.2 to 2.4 Ib
   of solids per year per cu ft (36 to 39 kg/m3) of capac-
   ity. A minimum of two separate lagoons are provided
   to ensure availability of storage space during clean-
   ing, maintenance, or emergency  conditions.

 • General Guidance. Lagoons may be of any shape,
   but a rectangular shape  facilitates rapid sludge re-
   moval.  Lagoon dikes should  have a slope of  1:3,
   vertical to horizontal, and should be of a shape and
   size to facilitate  maintenance, mowing,  passage of
   maintenance vehicles atop the dike, and access for
   the entry of trucks  and  front-end loaders into the
   lagoon. Surrounding areas should be graded to  pre-
   vent surface water from entering  the lagoon. Return
   must exist for removing the surface liquid and piping
   to the treatment plant. Provisions  must also be made
   for limiting public access to the sludge lagoons.

Design  criteria  for drying lagoons are presented in
Table 7-7; Table 7-8 lists advantages and disadvantages
of sludge drying lagoons.
 7.5.4  Design of Piles and Mounds

 Piles and mounds are sites where dewatered sludge is
 placed on part of the POTW property as final disposal.
 In general, piles and mounds are suitable only for stabi-
 lized sludges with a high chemical content (greater than
 40 percent lime plus some ferric) or a very low organic
 content (less than 50 percent solids), or for highly stabi-
 lized lagoon sludges. Piles of mechanically dewatered
 sludge with less than 25 percent solids usually lose all
 semblance of stability when exposed to extensive rain-
 fall (U.S. EPA, 1979).

 As surface disposal  facilities,  piles  and mounds are
 subject to the requirements of the Part 503 rule (e.g.,
 requirements for pathogen control, vector attraction re-
 duction, pollutant limits, siting,  restriction of public ac-
 cess, runoff collection, and ground-water protection). To
 protect ground water, it  is recommended that piles and
 mounds be located on an impervious surface (U.S. EPA,
 1990). Many  states also have regulations regarding
 sludge stockpiles. Check with your state for any specific
 state requirements for sludge stockpiles.

 7.5.5  Slope Stability and Dike Integrity

 Certain  types of monofills  (area fills) and surface im-
 poundments are  constructed  abovej natural grade
through the use  of  earthen  dikes,  excavated below
 grade slopes constructed around the unit, or some com-
 bination of  dikes and excavation, depending on  site
topography. These excavated slopes and earthen dikes
are vulnerable to stability failures via several  mecha-
nisms. Slope and dike failures can seriously damage a
liner system, allowing releases of leachate to surround-
ing soils and ground water.

For these reasons,  earthen  dikes must be carefully
designed,  and excavated slopes must be  carefully
evaluated  to ensure that they are sufficiently stable to
Table 7-7. Design Criteria for Drying Lagoons (Lue-Hing et al., 1992)
                                                             Design Parameter
                         a. Solids loading rate
                              Primary sludge
                              —(lagoon as a digester)
                              Digested sludge
                              —(lagoon for dewatering)

                         b. Area required
                              Primary sludge
                              (dry climate)
                              Activated sludge
                              (wet climate)
                         c. Dike height
                         d. Sludge depth after
                            decanting—depths of 60 cm
                            to 1.2 m (2-4 ft) have been
                            used in very warm climates
                         e. Drying time for depth of 38
                            cm (15 in) or less
      96.1 kg/m /year
      (6 Ibs/ft3/year)
      35-38 kg/m3/year
      (2.2-2.4 Ibs/ff/d)
      0.0929 mz/capita
      (1 ft/Vcapita)
      0.31586 m2/capita
      (3.4 ft2/capita)
      60 cm (2 ft)
      38 cm (15 in.)
      3 to 5 months
                                                   114

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Table 7-8.  Advantages and Disadvantages of Using Sludge Drying Lagoons (U.S. EPA, 1979)
                       Advantages                                   Disadvantages
     Lagoons are low energy consumers
     Lagoons consume no chemicals
     Lagoons are not sensitive to  sludge
       variability
     The lagoons can serve as a buffer in the
       sludge handling flow stream.   Shock
       loadings due  to treatment plant upsets'
       can be discharged to the lagoons with
       minimal impact
     Organic matter  is further stabilized
     Of all the dewatering systems available,
       lagoons require the least amount of
       operation attention and skill
     If land is available, lagoons have a very
       low capital cost
                                    Lagoons may be a source of periodic odor
                                       problems, and these  odors may be difficult
                                       to control
                                    There is a potential for pollution of
                                       groundwater or nearby surface water
                                    Lagoons can create vector problems  (for
                                       example, flies and mosquitos)
                                    Lagoons are more visible to the general
                                       public
                                    Lagoons are more land-intensive than fully
                                       mechanical methods
                                    Rational engineering design data are
                                       lacking to allow sound engineering
                                       economic analysis
withstand the loading and hydraulic conditions to which
they will be subjected during the unit's  construction,
operation, and post-closure periods. This section de-
scribes how to design and evaluate dikes and slopes for
stability. For more information on slope stability and dike
integrity at land disposal facilities, including information
on materials specifications and embankment construc-
tion, the-reader is referred to references  U.S.  EPA,
1988a, and U.S. EPA 1993a.
   *'_.-*"     v-  " ,             -".
7.5.5.1  Slope Stability Failure .  :

Sloperstabiiity failures  occur when sliding forces from
the'weight of the  soil  mass itself and  external forces
including sludge pressures exceed the  resisting forces
from the strength  of the soil and from, any reinforcing
structures. Slope stability analysis' consists of a com-
parison of these resisting forces (or:moments) to the
sliding forces" (or moments) to obtain, a factor  of
safety (FS). Generally, the  FS takes the following form
(Sowers, 1979):
           FS =
Sum of resisting moments
 Sum of sliding moments
 When a stability analysis is performed, a slope is ana-
 lyzed  for one or more of  several potential modes of
 failure. A safety factor is obtained for each mode,  the
 lowest FS being the most critical.

 Table  7-9 lists the EPA-recommended minimum factors
 of safety for slope stability analyses. If a dike or exca-
 vated  slope design analysis yields lower safety factors,
 then steps should be taken to reduce the sliding forces
 or increase the resisting forces, or the slope should be
 redesigned to produce a safer structure.

 Slope stability failures usually occur in one of three
 major modes, depending on the site soils, slope configu-
 ration, and hydraulic conditions (U.S. Dept. of the Navy,
 1982). These three major failure modes are the following:
• Rotation on a curved slip surface approximated by a
  circular arc.

• Translation on a planar surface that is large com-
  pared to the depth below ground.

• Displacement of a wedge-shaped mass along one or
  more planes of weakness in the slope.

Figure 7-19 illustrates basic concepts of rotational and
translational failures.

In addition to the three major failure modes, dikes and
excavated slopes are also vulnerable to failure due to
differential settlement, seismic effects including lique-
faction, and seepage-induced piping failure. Safety fac-
tors are determined in a manner similar to those for the
three major failure modes. These failure modes are
discussed in greater detail below.

7.5.5.2  Stability Analyses

A stability analyses should consider (U.S. EPA, 1988a):

• The adequacy of the subsurface exploration program.

• The stability of the dike slopes and foundation soils.

• Liquefaction potential of the soils in the dike and the
  foundation.

• The expected  behavior of the dike when subjected to
  seismic effects.

• Potential for seepage-induced piping failure.

• Differential settlements in the dike.

Subsurface Exploration Program

As discussed in Section  7.5.1, field investigations are
necessary to evaluate the foundation for a constructed
dike, to evaluate dike materials obtained from a borrow
area, and to evaluate a slope excavated below ground.
Of particular importance  in some circumstances are
laboratory strength tests  performed on soil samples to
                                                   115

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Table 7-8.  Ricommended Minimum Values of Factor of Safety for Slope Stability Analyses (U.S. EPA, 1988a)
                                                                           Uncertainty of Strength Measurements
                      Consequences of Slope Failure
                             Smallt
    Largea
       No imminent danger to human life or major environmental
       Impact if slope fails
       Imminent danger to  human life or major environmental impact if
       slope fails
                              1.25
                              (1.2)"

                               1.5
                              (1.3)
     1.5
     (1.3)
 2.0 or greater
(1.7 or greater)
       1. The uncertainty of the strength measurements is smallest when the soil conditions are uniform and high quality strength test
         data provide a consistent, complete, and logical picture of the strength characteristics.
       2. The uncertainty of the strength measurements is greatest when the soil conditions are complex and when available strength
         data do not provide a consistent, complete, or logical picture of the strength characteristics.
       *  Numbers without parentheses apply for static conditions and those within parentheses apply to seismic conditions.
             Active Wedges
Central Block
                                                                                     Passive Wedges
          ^	... —...

 x^/py//x4/xx/jx
                                  Elements of the Translation^ (Wedge) Slope Stability Analysis
                                                    (Reference 4, p. 42)
                                                                                                        Water
                  a.   Circular segment divided into slices
                               b.   Forces acting on slice 3
       Method of Slices for Circular Arc Analysis of Slopes in Soils Whose Strength Deoends on Stress (Reference 3. o. 578)

Figure 7-19.  Conceptual slope failure models (U,S. EPA, 1988a).
                                                             116

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determine the strength of the foundation and embank-
ment soils under the expected conditions of saturation
and consolidation (see Chapter 6).

Field and laboratory data are used to obtain a detailed
characterization of the site with respect to the engineer-
ing properties of the soils and rock. These engineering
properties provide the  input data for evaluation of the
stability of slopes. Slope stability analysis  requires the
establishment of various site conditions including (U.S.
EPA, 1988a):

• The soil shear strength conditions that represent ac-
  tual site conditions.

• The steady-state  hydraulic boundary conditions oc-
  curring through the site's section.

• The seismic conditions established for the site area.

For slope stability analyses,  the most critical soil pa-
rameter is that of shear strength (U.S. EPA, 1988a). The
shear strength of  a soil is  a measure of the amount of
stress that is required  to produce failure in plane of a
cross section of the soil structure. The shear strength of
a soil must be known before an earthen structure can
be designed and built with assurance that the slopes will
not fail (U.S. EPA, 1986b). To adequately  determine a
soil's shear strength, the potential effect of pore water
pressures from the  expected site loading conditions
must be considered during testing.
While laboratory soil strength testing data  is highly de-
sirable,  these tests  are limited to small-size samples,
and  in many locations dikes are constructed using ma-
terial that contains large particle  sizes. Furthermore, in
existing dikes, the type of material may make the obtain-
ing  of  undisturbed  soil samples nearly impossible.
Therefore, it is not uncommon in standard engineering
practice to estimate or assume these parameters based
on the best data available. While it is acceptable to do
this,  it  must be  done  and evaluated  by a qualified
geotechnical engineer (U.S. EPA, 1988a).

Slope stability also is dependent on hydraulic conditions
in the slope. Potential  hydrostatic or seepage  forces
from large hydraulic gradients should be identified and
considered during the stability analyses. Ground-water
levels and hydraulic analyses are used to determine the
configuration of the  steady-state piezometric surface
through sections of the foundation and/or the dike struc-
ture. For sections involving a steep piezometric surface
or an upstream static or flood pool, hydraulic analyses
also  determine seepage quantity, critical (highest) exit
gradient, and potential for uplift of a clay liner  due to
excess pore pressures produced  by a confined seepage
condition (U.S. EPA,  1986b).

Hydraulic boundary conditions may reflect unconfirmed,
steady-state seepage conditions, or confined seepage
conditions involving an impermeable barrier (soil liner)
and excess pore pressure on the barrier. The hydraulic
conditions of a slope are determined using seepage
analysis, as discussed by Freeze and Cherry (1979).

Slope Stability

Slope stability analyses are performed for both  exca-
vated side slopes  and aboveground embankments.
Three analyses will typically be performed as appropri-
ate to verify the structural integrity of a cut slope or dike;
they are (U.S. EPA, 1988a):

• Slope stability

• Settlement

• Liquefaction

Table 7-10 indicates the minimum required soil parame-
ter data usually needed to perform these analyses.

The slope stability is typically evaluated using either a
rotational  (slip circle) analysis and/or a  translational
(sliding  block or wedge)  analysis  using  a computer
model. These analyses are  run for both static and dy-
namic (seismic) conditions. For large dikes in areas of
major earthquakes, a more rigorous method of dynamic
analysis may be warranted.

Analyses to establish total  and differential settlement
are also performed to ensure that the estimated settle-
ment will not adversely affect the integrity of the unit and
its components.

The liquefaction analysis  determines the potential for
liquefaction of the dike  and foundation soils to  occur
during seismic events.

Rotational Slope Stability Analysis. A rotational  slope
stability analysis is typically  performed using a method
that divides the slope into discrete slices and sums all
driving and resisting forces  on each slice (see Figure
7-19). For each trial arc, the section is subdivided into
vertical  slices, each having  its base coincident with a
portion of the trial arc. Slices are defined  according to
the section geometry such that the  base of each slice
comprises only one soil type. The driving and resisting
forces acting on each slice  are then used to compute
driving and resisting moments about the center of rota-
tion of a circular section of the slope. The overturning
and resisting  moments for each slice are then summed
and the FS is computed (U.S. EPA,  1986b).

Translational Slope Stability Analysis. The major fea-
tures of the translational analysis are the same as those
for the rotational case except that the trial surface con-
sists of straight line segments that form the base of one
or more active (thrusting) wedges, a neutral or thrusting
central  block, and one .or more passive (restraining)
wedges (see  Figure 7-19). This analysis is based upon
selection of a trial central block defined by the surface
and subsurface soil layer geometry, followed by compu-
                                                   117

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Table 7-10. Minimum Data Requirements for Stability Analysis Options (U.S. EPA, 1988a)
                                                                     Stability Analysis Options
Soil Parameter
1. Cohesion* (UU. CU, CD cases)
2. Angle of internal friction* (UU. CU. C
cases)
3. Total (wet) unit weight
4. Clay content
5. Overconsolkfation ratio
6. Initial void ratio
7. Compression index
8. Recompression index
9, Hydraulic conductivity" (permeability, k)
10. Median grain size
11. Plasticity index (PI)
12. Liquid limit (LL)
13. Standard penetration number (N)
Units Rotational
pounds/sq.ft. (psf) X
degrees X
pounds/cu. ft. (pcf) X
percent (0 to 100)
unitless (decimal)
unitiess (decimal)
unitless (decimal)
unitless (decimal)
; ft/yr
mm
percent (0 to 100)
percent (0 to 1 00)
unitless (integer)
Translational Settlement Liquefaction
X XCD
X
XXX
X
X
X
X
X

X
X
X
X
      Required strength case dependent upon hydraulic boundary condition selected
      Used only in hydraulic analysis
tation of the coordinates for the associated active and
passive wedges (U.S. EPA, 1986c).

Settlement Analysis. Settlement analysis is used to de-
termine  the compression  of foundation soils  due to
stresses caused by the weight of an overlying dike.
Required parameters for each soil include unit  weight,
initial void ratio, compression and recompression  indi-
ces, and the over-consolidation ratio (U.S. EPA,  1986c).
Settlements are calculated at the toes, crest points, and
centerline of the dike. The consolidation of each soil is
calculated for each layer and summed up for all soils to
determine the total settlement at each point. Differential
settlements are calculated between each toe and crest,
toe and centerline, and crest and centerline on both
sides of the dike.  Recommended maximum differential
settlements can be found in EPA, 1986c.

Liquefaction Analysis. Factors that most influence lique-
faction  potential are  soil type,  relative density,  initial
confining pressure, and the intensity  and duration of
earthquake motion (U.S. EPA, 1986c).  Methods for es-
timating the potential for liquefaction are provided in a
computer software package called Geotechnical Analy-
sis for Review of Dike Stability (CARDS) that has been
developed by EPA's Risk Reduction Engineering Labo-
ratory (RREL) to assist permit writers and designers in
evaluating earth dike stability. GARDS details the basic
technical concepts and operational procedures for the
analysis of  site hydraulic conditions,  dike slope and
foundation stability, dike settlement, and liquefaction po-
tential of dike and foundation soils. It is designed to meet
the expressed  need for a  geotechnical support tool to
facilitate evaluation of existing and proposed dike struc-
tures at hazardous waste sites.
For additional information on seismic risk zones of the
United States,  the range of seismic parameters for
source zones, and GARDS, the reader is referred to
EPA, 1986c.

7.5.5.3   Slope; Stability Design Plans

The design plans for dikes and cut slopes should show
the design layout, cross sections  portraying the pro-
posed grade and bearing elevations relative to the ex-
isting grade,  and  details of the dikes or cut slopes,
including all slope angles and dimensions. Materials
present at the cut  slope or to be used to construct the
dike must be  adequately characterized  (see  EPA,
1986b). This design configuration then must be evalu-
ated for its stability under all potential  hydraulic and
loading  conditions. If the stability analyses result in un-
acceptably low factors of safety, then the design must
be modified to stabilize the slope. The revised design must
then be evaluated  to verify that it is sufficiently stable.

In addition, in a monofill or surface impoundment, often
the cut slopes or dikes will not be identical around the
entire perimeter of the unit. For this reason, it is impor-
tant that the most critical slope or dike section be iden-
tified for analysis. Generally, the most critical section will
be the steepest and/or the highest  portion of the slope
or dike. Particularly in a cut slope,  however, the in situ
materials may vary enough that the more critical slope
may be shallower or flatter, but may be composed of
weaker soils or may be subject to significant pore pres-
sures or seepage from high ground-water levels.

7.5.6   Liner Systems

Current regulations for sewage sludge surface disposal
sites (Part 503, Subpart C)  do not require that land
                                                   118

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disposal facilities be constructed  with  liner  systems.
Twenty-eight states and Puerto Rico, however, do spec-
ify some requirement for liners at sludge landfills (U.S.
EPA, 1990). Under the Part 503 regulation, where there
is a liner, the owner/operator of a surface disposal site
must maintain and operate a leachate collection system
(see Section 7.2.1). This section provides criteria for the
design and  construction  of liner systems and reviews
liner system designs on a component-by-component
basis. An extensive body of literature has been devel-
oped on the design of liners  and leachate collection
systems. For additional information on these systems,
including information on  materials  specifications, con-
struction procedures, and quality control issues, see the
references U.S. EPA, 1988a, and U.S. EPA, 1993b.

There are two types of liner systems currently used in
land disposal facilities. A single liner system consists of
one liner and one leachate collection system as shown
in Figure 7-20. A double liner system includes two liners
(primary and secondary), with a primary leachate collec-
tion system  above the primary (top) liner and a secon-
dary leak detection/leachate collection system between
the two liners, as shown  in  Figure 7-21.

The term "liner system" includes the liner(s), leak detec-
tion/leachate collection system(s), and any special ad-
ditional  structural components such as filter layers or
reinforcement. The major components  of  both single
and double liner systems are the following:

• Low-permeability soil liners

• Flexible membrane liners (FML)

• Leachate  collection and removal systems (LCRS)
                           7.5.6.1   Low-Permeability Soil Liners

                           Low-permeability soil liner design is siter and material-
                           specific. Prior to design, many fundamental yet impor-
                           tant criteria should be  considered such as: in-place
                           permeability of the liner;  liner stability against slope
                           failure, settlement, and bottom heave; and the long-term
                           integrity of the liner.

                           Important criteria to consider when reviewing a design
                           for a soil liner include (U.S. EPA, 1988a):

                           • Liner site and material selection

                           • Hydraulic conductivity

                           • Liner thickness

                           • Strength and bearing capacity

                           • Slope stability and controls for liner failure

                           These design considerations are important throughout
                           the installation and construction phases of a clay liner.

                           Site and Material Selection

                           A  site investigation should be conducted prior to the
                           design phase, and the following factors should be con-
                           sidered (see Chapter 6):

                           • Site geology

                           • Topography (especially drainage patterns)

                           • Analyses of soil properties

                           • Field and laboratory hydraulic conductivity

                           • Bedrock characteristics

                           • Hydrology

                           • Climate
         Protective
        Soil or Cover
         (optional)
Filter Medium
     Leachate
   Collection and
  Removal System
       Being Proposed as the
      Leak Detection System
                                          Low Permeability Soil
                                          Native Soil Foundation
                                                         Lower Component
                                                         (compacted soil)
                                                                                      (Not to Scale)
Figure 7-20. Schematic of a single clay liner system for a landfill (U.S. EPA, 1988a).
                                                   119

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         Protective
        Soil or Cover
         (optional)
                            Filter Medium
                    Top Liner
                     (FML)
Bottom Composite
      Liner
Primary Leachate
  Collection and
Removal System

       Secondary Leachate
          Collection and
         Removal System

Being Proposed as the
Leak Detection System
                                                                                                Upper
                                                                                              Component
                                                                                                (FML)
                                          Native Soil Foundation
                   Leachate
                   Collection
                    System
                    Sump
Lower Component
 (compacted soil)
Figure 7-21.  Schematic of a double liner and leak detection system for a landfill (U.S. EPA, 1988a).
All these factors are important to the design of the soil
liner. The site will require a foundation designed to con-
trol settlement and seepage and to provide structural
support for the liner (see Section 7.5.1). If satisfactory
contact between the liner and the natural foundation is
achieved, settlement and cracking will be  minimized
(U.S. EPA, 1988a).

Soil liners for sewage sludge disposal units must meet
the following requirements:

• Afield hydraulic  conductivity of 1 x 10'7 cm/sec when
  compacted.

• Sufficient strength after compaction to support itself
  and the overlying materials without failure.

Soil liner material  may originate at the site or may be
hauled in from a nearby borrow site if the native soil is
not suitable. If the available soils do not achieve the
specified hydraulic conductivity, it may be necessary to
introduce a soil  additive to  increase the performance
potential of the selected material. The most common
additive used to  amend soils is sodium bentonite (U.S.
EPA, 1993b). Although soil additives are known to de-
crease hydraulic conductivity, it is important to test ad-
ditives under actual field conditions as with any potential
soil liner material  (U.S. EPA, 1987b).  For additional
information on soil additives, see U.S. EPA, 1993b.

Because physical  properties differ from one soil to the
next, testing procedures are necessary to assist in the
selection of liner material. Once potential soil  sources
have been identified, it is necessary to begin testing to
eliminate undesirable soils or to determine whether the
source requires an amendment. Many procedures have
been standardized for soil testing by organizations such
as the American Society of Testing and Materials (ASTM)
and  by individuals currently researching clay soils for
use in soil liner construction (ASTM, 1987; U.S. EPA, 1986d).

Representative samples of the proposed material must
be subjected to laboratory testing. This will establish the
properties of the material with respect to water content,
density, compactive  effort, and hydraulic conductivity.
Clay soils  exhibit characteristic changes  when com-
pacted; therefore, all analyses of a  potential material
must be performed on a compacted sample. Table 7-11
provides a listing  of pertinent soil tests and methods
(U.S. EPA, 1986d).

Thickness

Two feet of soil is generally considered the minimum
thickness needed to obtain adequate compaction to met
the  hydraulic  conductivity  requirement  (U.S.  EPA,
1993b). Liners are designed to be of uniform thickness
over the entire facility. The  2-ft minimum thickness is
believed to be sufficient to inhibit hydraulic short-circuit-
ing of the entire layer (U.S. EPA, 1993b). Thicker areas
may be encountered wherever there may be recessed
areas for leachate collection pipes or collection sumps.
Some engineers suggest extra thickness and compac-
tive effort for the edges of the sidewalls to adequately
tie them together with the liner itself. In smaller facilities,
a soil liner  may be  designed  for installation over the
entire area, but in  larger or multicell facilities, liners are
designed  in segments. If this  is the case, it will be
necessary to specify in the design a beveled or step-cut
joint between  segments to  ensure that the  segments
properly adhere together (U.S. EPA, 1988b).

Hydraulic Conductivity

The coefficient of permeability or hydraulic conductivity
expresses the  ease with which water passes through
a soil. Achieving the hydraulic conductivity standard
                                                   120

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Table 7-11. Methods for Testing Low-Permeability Soil Liners
          (U.S. EPA, 1988a)
Parameter to be
Analyzed
SoMtyp*




Moisture content



In-place density



Moisture-density
Methods
Vitual -manual
procedure
Particle size analysis
Atterberg limits
Soil classification
Oven-dry method
Nuclear method
Calcium carbide
(speedy)
Nuclear methods
Sand cone
Rubber balloon
Drive cylinder
Standard effort
Test Method Reference
ASTMD24W

ASTMD422
ASTM 04318
ASTM 02487
ASTM D2216
ASTM 03017
AASHTO T217

ASTM D2922
ASTMD15S6
ASTM D2167
ASTM D2937
ASTM 0698
   relations
Strength
 Cohesive soil
   consistency (field)
 Hydraulic conductivity
   (laboratory)
Modified effort
Unconfirmed
compressive strength
Triaxial compression

Penetration tests

Field vane shear test
Hand penetrometer

Fixed-wall double ring
permeameter

Flexible wall
permeametar
 Hydraulic Conductivity Sealed Doubte-Rind
   (field)           Infiltrometer
                  Sai-Anderson-Gill
                  double-ring
                  Infittrorrwtor
ASTM Oi 557
ASTM 02166

ASTM 02850

ASTM D3441

ASTM 02573
Horslev, 1943

EPA, 1983 SW-870
Anderson et al,
1984
Daniel et at., 1985
SW-846 Method
9100 (EPA, 1984)

Day and Daniel,
1985
Anderson et a).,
1984
 (1 x 10~7 cm/sec) depends on the degree of compaction,
 compaction method, type of clay, soil moisture content,
 and density of the  soil  during liner construction (U.S.
 EPA, 1993b). Hydraulic conductivity is the most critical
 design criterion for a potential soil liner  (U.S. EPA,
 1988a). The hydraulic conductivity of a soil depends in
 part on the viscosity and density of fluid flowing through
 it. The hydraulic conductivity of a partially saturated soil
 will be less than the hydraulic conductivity of the same
 soil when saturated. Because invading water only flows
 through water-filled voids (and not air-filled voids), the
 dryness  of a soil tends to lower its permeability (U.S.
 EPA, 1993D).

 When designing a soil liner, field hydraulic conductivity
 is the most important factor to consider. Hydraulic con-
 ductivity testing should be conducted on samples that
are fully saturated to attempt to measure the highest
possible hydraulic conductivity (U.S. EPA, 1993b).

Strength and Bearing Capacity

Another important criterion to consider when designing
a soil liner is the strength and bearing capacity of the
liner material. Analysis of these parameters will deter-
mine the stability of the liner  material. More detailed
discussions of bearing  capacity and strength can be
found in Section 7.5.1.3.

Slope Stability

The strength  of a soil  also  controls its resistance  to
sliding. Failure of a liner slope can  result in slippage of
the compacted soil  liner along the excavated  slope.
Therefore, analysis of slope stability must be considered
in the design of a soil liner (see Section 7.5.5).

7.5.6.2  Flexible Membrane Liners (FMLs)

The design of a lined sewage sludge  surface disposal
site requires consideration of more than the perform-
ance requirements of the FML; it also requires careful
design of the foundation supporting the FML (see Sec-
tion 7.5.1). The foundation provides support for the liner
system, including the FMLs and the leachate collection
and removal systems. If the foundation  is not structurally
stable, the liner system may deform, thus  restricting or
preventing its proper performance.

Performance Requirements of the FML

The performance requirements of an FML include (U.S.
EPA, 1988a):
• Low permeability to waste constituents

• Strength  or mechanical compatibility of  the sheeting

• Durability for the lifetime of the facility
The designer must specify  the necessary criteria  for
each of these properties based on  engineering require-
 ments, performance requirements,  and the specific site
conditions.  In addition, the FML design must be compat-
 ible with the present technology, used  in the installation
 of FMLs (U.S. EPA, 1988c).
These performance requirements are assessed through
 laboratory and pilot-scale testing of the various proper-
 ties of FML sheeting (U.S. EPA, 1988c). The analyses
 and tests that are performed on FML sheeting measure
 its inherent analytical  properties,  physical properties,
 permeability characteristics, environmental  and aging
 properties,  and performance  properties  (U.S.  EPA,
 1988c). Testing  is essential to the designer/engineer
 who uses the data to determine whether a specific FML
 sheeting will meet the design requirements of the waste
 facility. These tests are discussed  in detail in the refer-
 ences U.S. EPA, 1983a, and U.S.  EPA, 1988c.
                                                     121

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Permeability

The primary function of a liner system  in a sewage
sludge surface disposal site is to minimize and control
the flow of leachate from the site to the  environment,
particularly the ground water. A properly designed FML
has a low permeability to the sewage sludge contained
within the liner, allowing it to perform its primary function.

Mechanical Compatibility

An FML must be mechanically compatible with the de-
signed use of the lined facility  in order to maintain its
integrity during  and after exposure to short-term  and
long-term mechanical stresses. Short-term mechanical
stresses can include equipment traffic during the instal-
lation of a liner system, as well as thermal expansion
and shrinkage of the FML during operation  of the unit.
Long-term mechanical stresses usually result from the
placement of sewage sludge on top of the liner system
or from differential settlement  of the subgrade (U.S.
EPA, 1988c).

Mechanical compatibility requires adequate friction be-
tween the components of a liner system, particularly the
soil subgrade and the FML, to ensure that slippage or
sloughing does not occur on the slopes of the unit.
Specifically,  the foundation  slopes and the subgrade
materials must  be considered  in design equations in
order to evaluate (U.S. EPA, 1988c):
• The  ability of an FML to support its own weight on
  the side slopes.
• The ability of an FML to withstand downdragging dur-
  ing and after filling.
• The  best anchorage configuration for the FML.
• The  stability of a soil cover on top of an FML.

Durability

An FML must exhibit durability; that,is, it  must be able
to maintain its integrity and performance characteristics
over the operational life and the post-closure care period
of the unit. The  service life of an FML is dependent on
the intrinsic durability of the  FML material and on the
conditions to which it is exposed (U.S. EPA, 1988c; EPA,
1987a; EPA, 1987b).

Selection of the FML

The performance  requirements determined by a de-
signer/engineer serve as the basis for the selection of
an FML for a given facility. Based upon the designed
use of the unit,  the designer must make decisions on
the composition, thickness,  and construction  (fabric-
reinforced or unreinforced) of an FML. Mechanical com-
patibility and sometimes  permeability determine the
thickness of the FML sheeting.  It should be noted that
liner performance  does not correlate  directly with any
one property (e.g., tensile strength) and that specifica-
tions that appear in specific technical  resource docu-
ments such as the reference EPA, 1988c, should not be
used alone as the basis for selection of an FML.

FMLs are made of polymeric materials, particularly plas-
tics and synthetic rubbers. There are four general types
of polymeric materials used  in the manufacture of FML
sheeting (U.S. EPA, 1988c):

• Thermoplastics and resins, such as PVC and EVA

• Semicrystalline plastics, such as polyethylenes

The various polymers are used to make a variety  of
liners that can be classified  by production process and
reinforcement.  Table 7-12 lists the  polymers currently
used in  lining materials (U.S. EPA 1988c).

The polymers used in FMLs  have different physical and
chemical properties, and they also  differ in method  of
installation and seaming as well as costs. The reference
U.S. EPA, 1988c, provides detailed information about the
composition and  properties of each of these polymers.

Seaming of FML Sheeting

The construction  of a continuous watertight FML is criti-
cal to the containment of leachate  and is heavily de-
pendent on the construction of the seams bonding the
sheeting together. The seams are the most likely source
of failure in an FML. Sheeting is  seamed together both
in the factory and in the field. Sheeting manufactured in
relatively narrow widths  (less than  90 in.) is seamed
together to fabricate panels. These factory seams are
made in a controlled environment and are generally of
high quality. Both fabricated  panels and sheeting  of
wider widths (21 to 64 ft) are seamed oh site during the
installation of the FML. The quality of field seams  is
difficult  to maintain  since the installer must deal with
changing  weather conditions, including temperature,
wind, and precipitation, as well as construction site con-
ditions,  which include unclean work areas and working
on slopes. Constant inspection  under a construction
quality assurance plan is necessary to ensure the integ-
rity of field searns (U.S. EPA, 1988c).

Several bonding systems are available for the construc-
tion of factory and field seams in FMLs. Bonding sys-
tems include solvent methods, heat seals, heat guns,
dielectric seaming, extrusion welding, and hot wedge
techniques. The  selection of a bonding system for a
particular FML is dependent primarily on the polymer
making  up the sheeting (U.S. EPA, 1988a).

7.5.7   Leachate Collection and Removal
        Systems (LCRSs)

Leachate refers  to liquid that has passed through  or
emerged from sewage sludge and contains dissolved,
suspended, or immiscible materials removed from the
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Table 7-12. Polymers Currently Used in FMLs for Waste Management Facilities (U.S. EPA, 1988c)

                                           Type of compound used in liners         Fabric reinforcement
Polymer
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyvinyl chloride (PVC-E)
Polyester elastomer (PEL)
Polyethylene (LDPE, LLDPE, HOPE)
Polyvinyl chloride (PVC)
Thermoplastic
Yes
Yes
Yes
Yes
Yes
Yes
Cross-linked
Yes
Yes
No
No
No
No
With
Yes
' Yes
Yes
Yes
No
Yes
Without
Yes
No
No
Yes
Yes
Yes
sewage sludge. The primary function of the leachate
collection system is to collect and convey leachate out
of the surface disposal unit and to control the depth of
the  leachate  above  the  liner  (U.S.  EPA,  1993b).
Leachate is generally collected from the surface dis-
posal unit through sand drainage layers, synthetic drain-
age  nets, or granular drainage layers with perforated
plastic collection  pipes, and is then removed through
sumps or gravity drain carrier pipes. An LCRS should
consist of the following components (U.S. EPA, 1988a):

• A  low-permeability base that  is either a soil  liner,
  composite liner, or flexible membrane liner (FML).

• A  high-permeability  drainage  layer constructed  of
  either natural granular materials (sand and gravel)  or
  synthetic  drainage material (geonet) that is placed
  directly on the  primary and/or secondary liner  or  its
  protective bedding layer.

• Perforated leachate collection pipes within the  high-
  permeability drainage layer to collect leachate and
  carry it rapidly to  the sump.

• A  protective filter material surrounding the pipes, if
  necessary, to prevent physical clogging of the  pipes
  or perforations.

• A leachate collection sump or sumps, where leachate
  can be removed.

• A  protective  filter layer  over the high-permeability
  drainage material that prevents physical clogging  of
  the material.

• A  final protective layer of material that provides a
  wearing surface for traffic and landfill operations.

The  design features of each of these components and
operation of the entire LCRS is summarized below. For
more detailed information, see the references U.S. EPA,
1993b, and U.S. EPA, 1988a.

7.5.7.1   Grading and Drainage

For leachate to be  effectively collected and removed,
liner systems must be sloped to drain toward their respec-
tive collection sumps. The recommended bottom liner
slope is 2 percent at  all points in each system (U.S. EPA,
1987b).  This slope  is necessary for effective leachate
drainage through the entire operating and post-closure
period; therefore, these slopes must be maintained un-
der operational and post-closure loadings. The settle-
ment estimates performed as discussed in Section 7.5.1
must be evaluated to ensure that the slopes will be 2
percent throughout the period of operation of the LCRS.
It may be necessary to initially design the slopes steeper
than 2 percent to allow for settlement (U.S. EPA, 1988a).

Good engineering practice requires that the design, con-
struction, and operation of the LCRS should maintain a
maximum height of leachate above the composite liner
of 30 cm (12 in.). Design guidance for calculating the
maximum leachate depth over a liner for granular drain-
age system materials is provided in U.S. EPA, 1989.

Granular Drainage Layers and Geosynthetic Drainage
Layer-Geonets

The  high-permeability drainage layer is placed directly
over the liner or the protective bedding layers. Often the
selection of a drainage material is based on  the onsite
availability of natural granular materials. Since hauling
costs are high for sand and gravel, a facility  may elect
to use geonets or synthetic drainage materials as an
alternative.  Frequently,  geonets  are  substituted  for
granular materials on steep sidewalls in order to provide
a layer that is more stable with respect to sliding than a
granular layer.

Geonets may be substituted for the granular layers in
either of the LCRSs on the bottoms and sidewalls of the
landfill  cells. Geonets may be used if their  charac-
teristics are in keeping with design, including chemical
compatibility, flow under load, clogging resistance, and
protection of the  FML (U.S. EPA, 1987c).

Piping

The design of piping systems requires the consideration
of pipe flow capacity and structural strength/The spac-
ing of  leachate  collection  pipes  can  be  determined
based on the maximum allowable leachate head on the
liner. This maximum head calculation assumes that liq-
uids  can drain away freely through the piping systems;
therefore, the pipes must be sized to carry the expected
flow  (U.S. EPA, 1988a).
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The leachate piping configuration shown on facility de-
sign drawings should be evaluated for its ability to main-
tain the maximum leachate head and for its ability to
carry the expected flows.

Sumps, located in a recess at the low point(s) within the
leachate collection drainage layer, provide one method
for leachate removal from a surface disposal unit. These
sumps typically house a  submersible  pump, which is
positioned close to the sump floor to pump the leachate
and to maintain a 30 cm (12 in.) maximum leachate
depth. Pumps used to remove leachate  from sumps
should be sized to ensure removal of leachate at the
maximum rate of generation. These pumps also should
have a sufficient operating capacity to lift  the leachate
to the required height from the sump to the access  port.
Portable vacuum pumps can be used if the required  lift
height is within the limit of the pump. They can be moved
in sequence from one leachate sump  to another. The
type of pump specified and the  leachate sump access
pipes should be compatible and should consider per-
formance needs under operating and closure conditions
(U.S.  EPA,  1988a).

Alternative methods of leachate removal include internal
standpipes and pipe penetrations through the geomem-
brane, both of which allow leachate removal  by gravity
flow to either a leachate pond or exterior pump station.
If a leachate removal  standpipe is  used,  it should be
extended through the entire surface disposal unit  from
liner to  cover and then through the cover  itself. If a
gravity drainage pipe that requires geomembrane pene-
tration is used, a high degree of care should be exer-
cised  in both  the design and construction of the
penetration so that it allows nondestructive quality  con-
trol testing of 100% of the seal between the pipe and the
geomembrane. If not  properly constructed and fabri-
cated, geomembrane penetrations can cause leakage
through the geomembrane (U.S. EPA, 1993b).

The HELP Model

EPA has developed a computer program called the Hy-
drologic  Evaluation of Landfill  Performance (HELP),
which is a  quasi-two-dimensional hydrologic  model  of
water movement across, into, through, and out of land-
fills. The model uses climatologic, soil, and landfill de-
sign data and incorporates a solution  technique that
accounts for the effects of surface storage runoff,  infil-
tration,  percolation, evapotranspiration, soil  moisture
storage, and  lateral drainage. The program  estimates
runoff drainage and leachate expected to result from a
wide variety of landfill conditions, including open,  par-
tially open,  and closed landfill cells. Most importantly, in
consideration of this topic, the model can be used  to
estimate the buildup of leachate above the bottom  liner
of the landfill. The HELP program can be used to  esti-
mate the depth of leachate above the bottom liner  for a
variety of landfill  designs, time averages, and storm
events. The results may be used to compare designs or
to design leachate drainage and collection systems.
References U.S. EPA, 1984a, and U.S. EPA, 1984b, a
user's guide  and model  documentation,  respectively,
should be obtained before attempting to run the HELP
model. Version 3.0 of the HELP model became available
during the fall of 1993. To obtain a copy, call EPA's Office
of Research and  Development (ORD) in Cincinnati at
513-569-7871.

7.5.7.2   System Strength

All  components of the  LCRS must have sufficient
strength to support the weight of the overlying sewage
sludge, cover system, and post-closure loadings, as well
as stresses from operating equipment  and from  the
weight of the components themselves. LCRs are  also
vulnerable  to sliding under their  own weight and  the
weight of equipment operating on the slopes. The com-
ponents that are most vulnerable to strength failures are
the drainage layers and piping.  LCRS piping can fail by
excessive deflection leading to  buckling or collapsing.

Sidewall Stability

For liner systems placed  on excavated  sidewalls,  the
issue of the stability of the individual liner components
on the slope,  including the LCRS, must also be consid-
ered. Koerner (1986) provides a method for calculating
the factor of safety against sliding for soils placed on a
sloped FML surface. It considers the slope angle and
the friction angle between the FML and its cover soil.

From the slope angle and  the FS, a minimum allowable
friction angle is determined, and the various compo-
nents of the  liner system are  selected  based on this
minimum friction angle. If  the design evaluation results
in an unacceptably low FS, then  either the sidewall slope
or the materials must  be  changed to produce an ade-
quate design.

Stability of Drainage Layers

If the drainage layer  of  the LCRS  is constructed of
granular soil materials (i.e., sand and gravel), then this
granular drainage layer must be  shown to have sufficient
bearing   strength   to  support  expected  loads.  The
leachate system  design  should  provide calculations
demonstrating that the selected granular drainage ma-
terials will be stable on the steepest slope (i.e., the most
critical) in the  design. The  calculations and the assump-
tions should be shown, especially the friction angle be-
tween the  geomembrane and soil, and if possible,
supported by  laboratory and/or field testing data.

Pipe Structural Strength

Pipes installed at the base of a landfill can be subjected
to high  loading of waste. The  evaluation of a design
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should consider both the maximum depth of fill over the
piping and the loading exerted by landfill equipment on
a pipe with very little cover. The pipe must be selected
based  upon the most critical of these loadings.

Leachate collection pipes beneath land disposal facili-
ties are generally installed in one of two configurations:

• A trench condition, where the pipe is  placed  in a
  shallow trench excavated into the underlying soil  liner
  or foundation soil and does not project above the top
  of the trench.

• A positive  projecting condition, where  the pipe  is
  placed directly upon a lower liner system component
  and  projects above it.
Loads on the pipe in the trench condition are caused by
both the fill material and the trench backfill. These two
loads are computed separately and then added to obtain
the total vertical pressure acting on the top of the pipe.
For the projecting condition the vertical pressure on the
pipe is assumed to be equal to the unit weight of the fill
multiplied by the height of the fill above the pipe (U.S.
EPA,1988a).
In the early phases of landfilling the piping system is
subject to concentrated and impact loadings from trucks
and landfill equipment. Since the pipe at this point  may
be covered with only a foot or so of granular drainage
material, wheel and impact loads are transmitted directly
to the pipes. These loads  may  be  calculated using a
method found in the reference ASCE/WPCF, 1969.  This
traffic  load should be compared  to the static load  from
the waste, and the pipe selected based upon the larger
of the  two loads.
Pipes  are slotted or perforated to allow flow of leachate
into the collection system. These perforations reduce
the effective  length of the pipe available to carry loads
and to resist deflection. See U.S.  EPA,  1983a for a
discussion of how to allow for perforations in  pipe
strength calculations.

7.5.7.3  Prevention of Clogging

The piping system must be protected from physical
clogging by the granular drainage materials. This is  most
effectively accomplished by careful sizing of pipe perfo-
rations and by surrounding the pipe with a filter medium,
either a graded granular filter or a geotextile material (a
filter fabric). In addition, clogging of the pipes and drain-
age layers of the LCRS can occur through several other
mechanisms, including chemical and biological  clog-
ging. For more information on these mechanisms, see
U.S. EPA, 1988a.

To prevent physical clogging of leachate drainage layers
and piping by soil sediment deposits, filter and drainage
layer size gradations should  be designed  using criteria
established by the Army Corps of Engineers. Drainage
layers should be designed to have adequate hydraulic
conductivity; and granular drainage media should be
washed before installation to minimize fines. Drain pipes
should be slotted or perforated with a minimum inside
diameter of 6 in. to allow for cleaning.

Two criteria are suggested for use in design of drainage
and filter layers for drain systems. The first criterion is
for the control of clogging by piping ofsmall soil particles
into the filter layer and the drain pipe system, while the
second criterion is meant to guarantee sufficient perme-
ability to prevent the buildup of large seepage forces and
hydrostatic pressure in filters and drainage layers. When
geotextiles are used in place of graded filters, the pro-
tective  filter may be only about 1 mm  in thickness.
Caution should be exercised to ensure that no holes,
tears, or gaps are permitted to form in the fabric. The
advantages  to  using geotextiles in place of granular
filters are cost, uniformity, and ease of installation. With
increases in costs of graded aggregate and its installa-
tion, geotextiles are competitive with graded filters. One
of the most important advantages to geotextiles is qual-
ity control during construction. The properties of geotex-
tiles will  remain practically constant independent  of
construction practices, whereas  graded filters can be-
come segregated during placement. These geotextiles
must be designed,  and the references Koerner, 1986,
and U.S. EPA,  1987c, provide guidance on how to de-
sign such systems.
When drainage pipe systems are embedded in filter and
drainage layers, no unplugged ends should be allowed,
and the filter materials in contact with the pipes rrjust be
coarse enough  to be excluded  from joints, holes,  or
slots. Specifications for the  drainage  layer materials
should be checked against pipe specifications to be sure
that the piping system will not become clogged by the
granular drainage layer particles.

7.5.7.4  Layout of System  Components

The design of an LCRS for a sewage sludge surface
disposal unit begins with a layout of the system compo-
nents within the unit. This layout should be presented in
plan view, cross-section, and detail drawings of the unit.
The drawings should show dimensions and slopes of
the unit design features and  all the components of the
LCRS.
The system components should be shown on the plan
and cross-section drawings and should clearly show the
lateral  and vertical extent of the liners. The drawings
should show the elevations of the tops of the liner sys-
tem components at critical points, including the toes of
the sidewalls, the boundaries of any sub-areas of the
unit that  drain to different sumps, and  the  inlet and
low-point elevations of the sumps. This information is
essential to evaluate the ability of the  system to drain
leachate toward the collection sumps.
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 7.5.7.5  Leachate Treatment

 Collected leachate may be treated by one or more of the
 following methods:

 • Discharge to a wastewater collection system or haul
   directly to a treatment plant.

 • On-site treatment.
   - Recycle through the landfill
   - Evaporation of leachate in collection ponds
   — Onsite treatment plant

 Depending on the leachate characteristics, volume, and
 local regulations, it may be possible to discharge col-
 lected  leachate to  an existing wastewater system for
 subsequent treatment with municipal wastewater. Local
 wastewater treatment plant personnel should be con-
 sulted about leachate acceptability to determine special
 requirements for discharge to the treatment plant (e.g.,
 large slugs of highly contaminated  leachate may have
 to be mixed with municipal wastewater to prevent plant
 upsets).

 If discharge to the wastewater system is not practical or
 if the leachate is potentially disruptive to treatment plant
 operations, onsite  treatment or transportation to  a
 chemical waste disposal site will have to be utilized.

 Onsite treatment may consist of recycling the leachate
 through the landfill, placing the  leachate  in a shallow
 basin to allow it to evaporate, or installing a small (spe-
 cially designed) treatment plant on site. Leachate recy-
 cling systems are not feasible at most sites; specifically
 at areas with high rainfalls and high application rates.
 The primary application of such systems should be re-
 stricted to codisposal sites in climates where the evapo-
 ration rate exceeds rainfall to a significant extent. The
 latter alternative should be avoided if at all possible
 due to its high cost  and the unproven reliability of such
 small plants.

 7.6  Design for Codisposal  with Solid
      Waste

 Codisposal is the disposal of sewage sludge with house-
 hold waste (solid waste) at an MSW landfill. Figure 7-22
 presents a generalized flow chart for codisposal of re-
 fuse and sewage sludge in a landfill. Methods of codis-
 posal include:

 • Landfilling a sewage sludge/solid  waste mixture.

 • Use of sewage sludge/soil mixture or sewage sludge
  as daily cover material.

 • Use of sewage sludge/soil mixture or sewage sludge
  as final cover material.

The design of MSW  landfills is regulated by EPA's Solid
Waste Disposal Facility Criteria, 40 CFR Part 258. This
 manual does not provide detailed information about
 the design of a solid waste landfill  receiving  sludge.
 Rather, it addresses only  the design features  that
 distinguish solid waste landfills receiving sludge from
 those not receiving sludge.  For information relating to
 the design and operation of an MSW  landfill,  consult
 U.S. EPA, 1993b.

 7.6.1  Sludge/Solid Waste Mixture

 In a sewage sludge/refuse mixture operation, sludge is
 delivered to the working face of the landfill where it is
 mixed and buried with the solid waste. At codisposal
 sites, some sludge  handling difficulties arise because
 the  sludge is more liquid in nature than the solid waste.
 These difficulties include the  following:

 • The sludge is difficult to confine at the working face.

 • Equipment  slips  and sometimes becomes stuck in
   the sludge while  operating at the working face.

 These difficulties can be minimized if proper planning is
 employed to control the quantity of sludge received at
 the solid waste landfill. Every effort should be made not
 to exceed the absorptive capacity  of the refuse. The
 maximum allowable sludge quantity will vary, primarily
 depending on the quantity of solid waste received and
 the  solids content of the  sludge. Table 7-13  presents
 some design considerations for codisposal landfills. This
 table includes suggested bulking ratios for sludge/refuse
 mixtures at various sludge solids contents, but determina-
 tions should be made on a site-by-site basis using test
 operations. It should be noted that any sludge disposed
 of in an MSW landfill must pass the paint filter liquids
 test  (Figure 7-23), as discussed in Section 3.4.3.

 A second planning and design consideration for sludge/
 solid waste mixture operations concerns leachate con-
 trol.  The impact of sewage sludge receipt on leachate
 at MSW landfills  is  highly site specific. Generally, in-
 creased  leachate  quantities should  be  expected.
 Leachate control systems  may have to be designed or
 modified accordingly.

 While sludge  might  be expected to degrade leachate
 quality in  an MSW landfill, a 4-year landfill simulator
 study (Stamm and Walsh,  1988) evaluating codisposal,
 municipal  refuse-only disposal, and sludge-only dis-
 posal found that codisposal had the least detrimental
 effect on leachate quality (Table 7-14), with the bulk of
 contamination being released approximately  1  year
 sooner than sludge-only or solid waste-only configura-
 tions. Codisposal also enhanced  the decomposition
 process as measured by  methane generation. Codis-
 posal test cells generated  methane  much sooner than
the refuse-only cell in this  study. This is  significant be-
cause methane collection and treatment is much more
effective in the early life of a landfill as compared to after
its closure.
                                                  126

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                                                                                   Landfill

                                                                                  • Spreading
                                                                                  • Covering
                                                                                  • Compacting
Sludge,
Input
. 	 f

Dewatering


•
('
Truck
Transport
Figure 7-22.  Landfill codisposal.
Table 7-13.  Design Considerations for Codisposal Operations
Design
Parameter Consideration
Method
Bulking ratio Sludge/refuse mixture

Sludge/soil mixture
Bulking
agent
Refuse

Soil
Sludge solids
content
10-17%
17-20%
20%
20%
Bulking ratio
6 tons refuse :1
5 tons refuse : 1
4 tons refuse : 1
1 soil : 1 sludge

wet ton sludge
wet ton sludge
wet ton sludge

 1 ton = 0.907 Mg
                                                                           Paint Filter
                                                     Funn
                                         •Ring Stand
                                                                   <•—Graduated Cylinder
 Figure 7-23.  Paint filter test apparatus (U.S. EPA, 1993).
                                                        127

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 Table 7-14.  Various Average Leachate Values for Codisposal, Refuse-Only, and Sludge-Only Test Cells Averaged Over 4 Years
            (Stamm and Walsh, 1988)
Par-meter Codisposal*
COD (mg/L)
TOC (mg/L)
PH
Volatile Acids (tng/i)
Volatile Solids (mg/L)
Specific .Volume . (L/kg/mo. )
2,889
903
7.1
868
2,171
0.03
Refuse-Only*
22,453
4,640
•6.4
7,434
7,659
0.03
Sludge-Only*
2.258
737
6.2
.1,213
5.555
0.07
                  *  Average of Cell  1, 5, and 9.
                  +  Average of Cell  17 and 19.
                  r  Average of Cell  21 and 23.

 A third planning and design consideration is storage for
 sludge received in off-hours. In many cases sludge is
 delivered around the clock, while solid waste delivery is
 confined to certain hours. Sludge storage facilities might
 have to be installed to contain sludge overnight or over
 weekends until sufficient refuse bulking is delivered.

 7.6.2   Sludge/Soil Mixture and Sludge as
         Daily Cover Material

 The Solid Waste  Disposal Facility Criteria require that
 all owners and operators of MSW landfill units cover
 disposed solid waste with 6 in. of earthen material at the
 end of each operating day, or at more frequent intervals
 if necessary,  to control disease vectors, fires, odors,
 blowing litter,  and scavenging. A state  may approve an
 alternative material  if the owner or operator  demon-
 strates that it controls  disease vectors, fires, odors,
 blowing litter,  and scavenging  without presenting a
 threat to human health and the environment.

 A sludge/soil mixture (in an approximately 1:1  ratio) may
 be a suitable  material  for daily cover. Some  landfills
 have used sludge mixed with compost as daily cover
 material (U.S. EPA, 1993a). In  a sludge/soil  mixture
 operation, sludge is mixed with soil and applied  as daily
 cover or as cover over completed solid waste fill areas.
 If a sludge/soil mixture operation is planned, an area
 must be reserved at the planning/design  stage  for
 sludge/soil mixing. This area must be of sufficient size
 and have  sufficient soil available for  sludge bulking.
 Information on suggested bulking ratios is included in
 Table 7-13. The soils in the mixing area must  also be
 adequate to protect the ground water.

 Sewage sludge also may be a suitable daily cover ma-
 terial if  it has  a solids content of 50 percent or higher
 and if it has undergone a process such as  biological
stabilization to reduce the volatile solids content. Sludge
with these characteristics has the following advantages
as daily cover  material (Lue-Hing et al., 1992):
 • It has a  high moisture absorption capacity, thereby
   helping to control insects, rodents, and other vectors
   that thrive under wet conditions.

 • Like soil, it has a high odor-absorbing capacity. It also
   reduces  the emission of  odorous gases from  the
   landfill by reducing the surface area of municipal solid
   waste exposed to the atmosphere.

 • Like soil, it acts as a physical barrier to control blow-
   ing litter  and improves the aesthetic appearance of
   the landfill.

 • If the volatile solids content of the sludge has been
   reduced,  it can reduce the fire hazard associated with
   municipal solid waste landfills. Municipal sewage
   sludge with a volatiles content of  50 to 55 percent
   has a flash point of approximately 250ฐC, making it
   suitable for use as a fire control agent at solid waste
   landfills.

 • It helps reduce the potential for leachate contamina-
   tion of ground water and surface water.

 Certain sludge-derived products have also been used
 as alternative  materials  for  daily cover at  landfills.
 Sludges can be treated by chemical fixation processes
 using additives such as lime, cement kiln dust, fly ash,
 and silicates to produce a suitable  soil-like material.
 Examples include the N-VIRO process, a patented pas-
 teurization and chemical fixation process in which dewa-
 tered sludge is blended with alkaline additives, cured,
 and then  aerated and windrowed.  Another process,
 CHEMFIX,  is a proprietary chemical fixation process
 using soluble  silicates  and  silicate  settling  agents
 blended with the sludge to produce a chemically and
 physically stable solid material. These and similar fixa-
tion processes require  the construction of sludge proc-
essing and curing facilities, possibly at significant capital
investment (U.S. EPA,  1993a).

To avoid workability problems when these sludge-de-
rived products  are placed on the working  face of a
                                                   128

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landfill, they must be cured and dried to a moisture
content of approximately 60 percent. At the proper mois-
ture content, they are reported to be lighter and easier
to spread than soil. An ammonia-like odor (usually re-
stricted to the working face) has been reported when
these products are initially placed on the working face.
To improve workability and control odors, the products
are sometimes blended with natural soil at a 1:1 ratio.
Problems with dust generation have also been reported
at some sites using sludge-derived products as daily
cover (U.S. EPA, 1993a).

7.6.3   Sludge/Soil Mixture and Sludge as
        Final Cover Material

The Part 258 regulation requires that when an  MSW
landfill has reached,the  end of  its useful life, it must
receive a final cover designed and constructed to have
a permeability less than or equal to the permeability of
the bottom liner system or the natural subsoils present,
or a permeability no greater than 1 x 10"5 cm/sec, which-
ever is less (Figure 7-24). The final cover must include
an infiltration layer composed of at least 18 in. of an
earthen  material (such as clay) to minimize the flow of
water into the closed landfill. The cover must also con-
tain an erosion layer to prevent the disintegration of the
cover. The erosion layer must be composed of a mini-
mum of 6 in. of earthen  material capable of sustaining
native plant growth.

 EPA  allows a state or tribe to approve an alternative
erosion  layer design that provides equivalent protection
from wind and water erosion. This may include the use
 of sludge/soil mixtures or sludge.

 Sewage sludge may be suitable as material for the
 erosion layer if it has a  solids content greater than 20
 percent and has undergone a process such as anaero-
 bic digestion to reduce its volatile solids content. About
 1 to 3 ft (0.3 to 0.9 m) of sludge is usually sufficient to
establish a vegetative cover. To prevent the sludge from
sliding down the side slopes, it should be mixed with the
surface soil at a 1:1 ratio (Lue-Hing et al., 1992).


7.7   Design Considerations for Dedicated
      Surface Disposal Sites

DSD  sites,  including  beneficial  DSD sites on which
vegetation is grown, must be designed to meet the Part
503  Subpart  C  surface  disposal requirements  for
leachate collection (unless  pollutant limits are  met),
aquifer protection, and collection of surface water runoff.
Other important design considerations at DSD sites in-
clude determining the most appropriate sludge disposal
method to use, calculating the acceptable sludge dis-
posal rate, ascertaining land area needs, the site's prox-
imity to needed community infrastructure, and climatic
considerations. Design considerations for DSD sites are
discussed below, with the exception of the collection of
surface water runoff, which is discussed in Section 7.9.1.

 7.7.1   Presence of a Natural Liner and Design
        of a Leachate Collection System

A well chosen DSD site will be completely underlain with
a relatively impervious soil such as clay with a hydraulic
conductivity of 1 x 10"7 cm/sec or less, thus meeting the
 Part 503 requirement for a liner as applicable to DSD
sites. If the DSD site owner is choosing to use this liner
to comply with Part 503 rather than by meeting pollutant
 limits, then Part 503 requires that leachate be collected
 at the site. If the DSD site contains both a liner and
 leachate collection system,  the  sewage  sludge  at the
 site is not required to meet the Part 503 pollutant limits
 for surface disposal.

 If the DSD site is not underlain with impervious soil, then
 the sewage sludge at the DSD  site  must meet the
 pollutant limits for arsenic, chromium, and nickel speci-
               Erosion Layer
                Min.6"Soil
              or Soil/Sludge
                Mixture
                      Infiltration Layer
                  Min. 18" Compacted Soil (1 x
                        10-5 cm/sec)
                                                        ^  k

                                                              Existing Subgrade

  Figure 7-24.  Example of minimum final cover requirements (U.S. EPA, 1993).
                                                    129

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  In addition to installing a leachate collection system to
  comply with Part 503, a subsurface drainage system to
  collect leachate may also need to be designed in areas
  with a high ground-water table. In addition to increasing
  the  potential for  ground-water contamination, a high
  ground-water table may  create serious problems for
  sludge disposal at DSD sites, such as ponding, anaero-
  bic soil conditions, or muddy surfaces.

  Buried plastic pipe or clay tile,  10 to 20 cm (4 to 8 in.) in
  diameter,  is generally used for underdrains. Concrete
  pipe is less suitable because of the sulphates that may
  be present in leachate from soils on which  sludge has
  been disposed. Underdrains usually are buried 1.8 to
  2.4 m (6 to 8 ft) deep, but can be as deep as 3 m (10 ft)
  or as shallow as 1 m (3 ft). Spacing of drains typically
  ranges from 15 m (50 ft) in clayey soils up to  120 m (400
 ft) in sandy soils. Procedures for determining the proper
 depth and spacing of drains can  be found  in other
 publications, such as EPA's Process Design Manual for
 Land Treatment of Municipal  Wastewater (U.S. EPA,
 1981), (U.S. Soil Conservation  Service, 1972), and (Van
 Schilfgaarde, 1974).

 If a subsurface drainage collection  system  is  installed
 beneath the DSD  site, the leachate collected from the
 system may need to be treated and will need to be
 properly stored and disposed or reused.

 7.7.2 No Contamination of Aquifers:
       Nitrogen Control at DSD Sites

 The DSD owner must prove that ground-water is not
 being contaminated, as specified in  Part 503 based on
 nitrate levels, through either a ground-water  monitoring
 program developed by a qualified ground-water scientist
 or certification by a ground-water scientist, as discussed
 in Chapter 4.

 Several topographical and design conditions at a DSD
 site will help in meeting the Part 503  regulatory require-
 ment for controlling nitrates so the site does not contami-
 nate an aquifer. These conditions include:

 • No  aquifer exists at potentially useful elevations.

 • It can be shown that the volume of leachate contain-
  ing  nitrates reaching the aquifer is such a small per-
  centage of the ground-water aquifer flow volume that
  potential  degradation is negligible.

• The local climate is arid  with a high  net evaporation
  rate, and useful aquifers are  deep.

• An impervious geological barrier, such as unfractured
  bedrock or thick clay, lies between the DSD site and
  a useful  aquifer and serves  as a liner, effectively
  preventing significant volumes of leachate from per-
  colating into the aquifer.
  • A below-ground leachate collection system is con-
    structed (e.g., drain tiles, well points, etc.) which collects
    the leachate before it can percolate into the aquifer.

  If none of the above possibilities is feasible, singly or in
  combination, then the site is probably an inappropriate
  location for a DSD site.
  7.7.3   Methods for Disposal of Sewage
         Sludge on DSD Sites


 The choice of sludge disposal methods at DSD sites
 are dictated by sewage sludge characteristics and often
 by cost and/or aesthetics (e.g., odors or other commu-
 nity concerns). The owner/operator of a DSD site has
 a number of  methods to choose from for sludge dis-
 posal, including:

 • Subsurface methods  for liquid  sludge, including (1)
   subsurface  injection or (2) plow or disc covering.

 • Surface spreading of liquid sludge by tank trucks or
   tank wagons.

 • Spraying of liquid sludge.

 • Surface spreading of dewatered sludge.

 Each disposal method has advantages and disadvan-
 tages which  are  discussed below.  Tables 7-15a  and
 7-15b describe the methods, characteristics, and limita-
 tions of disposing liquid sludge by surface methods and
 subsurface methods. In  all  of the  disposal techniques,
 the sludge eventually becomes incorporated  into the
 soil, either immediately by  mechanical means or over
 time by natural means.

 The technique used to apply sludge  to the land can be
 influenced by the means used to  transport the sludge
 from the POTW(s) to the DSD site. Commonly used
 methods include:

 • Same  transport vehicle both  hauls sludge from  the
  POTW to the DSD site and spreads  sludge on the land.

 • One type of transport vehicle, usually with  a large
  volume capacity, hauls sludge from the POTW to the
  DSD site. At the DSD  site, the  sludge haul vehicle
  transfers the sludge to an application vehicle, into a
  storage facility, or both.

• Sludge is pumped and transported by  pipeline from
  the POTW to a storage facility  at  the DSD site.
  Sludge is subsequently transferred from the  storage
  facility to the sludge application vehicle.
                                                 130

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Table 7-15a.  Surface Spreading Methods and Equipment for Liquid Sludges (Cunningham and Northouse, 1981)
Meth*i
Tank truck
Farm tank wagon
Characteristic*
Capacity 500 to more than
2,000 gallon*; itii desirable
to have flotation tires; can be
used with temporary
irrigation set-up; with pump
discharge can achieve a
uniform tpreading rate.
Capacity 500 to 3,000 gallons;
it is desirable for wagons to
have flotation tires; can be
used with temporary
irrigation set-up; with pump
discharge, can achieve a
uniform spreading rate.
Topographical amd SeuoBal
LiBllatira*
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.
                Metric conversion factor  1 gal ป 3.78 L
Table 7-15b.  Subsurface Spreading Methods, Characteristics, and Limitations for Liquid Sludges (Keeney et al., 1975) for Liquid
            Sludges (Cunningham and Northouse, 1981)
Mtthoi
Flexible irrigation hose with
plow or disc cover
Tank truck with plow or disc
cover
Farm tank wagon with plow
or disc cover
Subsurface injection
CharacUriitks
Use with pipeline or tank
truck with pressure discharge;
hose connected to manifold
discharge on plow or disc.
500-gallon commercial
equipment available; sludge
discharge 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,
disposal of 170 to 225 wet
tons/acre; or sludge spread in
narrow band on ground
surface and immediately
plowed under, disposal of 50
to 120 wet tons/acre.
Sludge discharge into channel
opened by a chUeTtool
mounted on tank truck or
tool bar, disposal rate 25 to
50 wet tons/acre; vehicles
should not traverse injected
area for several days.
Topognphk mi Seasonal
timttattou
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 = 224 metric tons/hectare
 7.7.3.1
Disposal Methods for Liquid Sludge at
DSD Sites
 Subsurface Methods
 Subsurface methods for disposal of liquid sludge at DSD
 sites have a number of advantages over surface meth-
 ods, including:
• Minimization of potential odor and other nuisance prob-
  lems, and thus possibly better public, acceptance.

• Reduction of potential surface water runoff.

• Conservation of nitrogen (because ammonia volatili-
  zation is minimized), which may be important if vege-
  tation is grown onsite.
                                                      131

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  Advantages of subsurface methods compared to spray-
  ing include:

  •  Greater amounts of sludge  can be  disposed per
    spreading activity

  •  Less visibility to the surrounding community

  •  Better disposal at DSD site perimeters

  Nevertheless, subsurface methods have a number of
  potential disadvantages compared to surface methods
  for liquid sludge, including:

  •  Possibly more difficulty in achieving even distribution
    of the sludge

  •  Higher fuel consumption costs than surface methods

  Subsurface incorporation  of liquid sludge can be done
  in  two basic ways—subsurface injection or plow or disc
  covering. Figures 7-25 through 7-27 illustrate one type
  of  vehicle designed specifically for subsurface injection
  of  liquid sludge which consists of a  tank truck with
 special  injection equipment attached. Tanks for the
 trucks are  generally available with 6,000, 7,500, and
 11,000 I (1,600, 2,000, and 3,000 gal) capacities. Figure
 7-28 shows another type of subsurface injection vehi-
 cle—a tractor with a rear-mounted injector unit. Sludge
Figure 7-26.  Tank truck with liquid sludge tillage injections
           (courtesy of Rickel Mfg. Co.).
                                        .TRACTOR AND  INJECTION UNIT
Figure 7-25.  Tractor and Injection unit.
                                                   132

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is  pumped from a storage facility to the injector unit
through a flexible hose attached to the tractor. Discharge
flow capacities of 570 to 3,800 l/min (150 to 1,000 gpm)
are used. The tractor requires a power rating of 40 to 60 hp.
The plow or disc cover method involves discharging the
sludge into a narrow furrow from a tank wagon or flexible
hose  linked to a storage facility  through a  manifold
mounted on a plow or disc; the plow or disc then imme-
diately covers  the sludge with soil. Figures 7-29a and
7-29b depict a typical tank wagon with an attached plow.
These systems seem  to be best suited for high loading
rates, (i.e., a minimum of 3.5 to 4.5 mt/ha [8 to 10 dry
T/ac]) of 5 percent slurry (Keeney et al., 1975).

Surface Methods
Surface spreading of  liquid  sludge involves  spreading
without subsequent incorporation into the soil. Surface
spreading is less expensive than subsurface injection in
 >.*•
Figure 7-29a.  Tank wagon with sweep shovel injectors (Cun-
            ningham and Northouse, 1981).
 Figure 7-27. Tank truck with liquid sludge grassland injectors
            (courtesy Rickel Mfg. Co.).
Figure 7-29b.  Sweep shovel injectors with  covering  spoons
             mounted on tank wagon (Cunningham and Nor-
             thouse, 1981).
  Figure 7-28.  Tractor pulled liquid sludge subsurface injection unit connected to delivery hose (courtesy Briscoe Maphis Co.).
                                                      133

-------
  terms of equipment and labor. But the DSD sites re-
  viewed during preparation of this manual  had experi-
  enced problems when using surface spreading methods,
  including odors, uneven distribution of sludge, clogging
  of soil surface, and difficult vehicle access into the area.

  Liquid sludge can  be  surface  spread  by vehicles
  equipped with splash plates or a slotted T-bar. Selection
  of either of these attachments should primarily be based
  on whichever method results  in the most  uniform
  spreading at an individual  site. Figure 7-30 depicts a
  tank truck equipped with splash plates, and  Figure 7-31
  depicts a tank truck with a rear mounted "T" pipe. For
  these  two methods, disposal rates can be controlled
  either by valving the manifold or by varying the speed of
the truck. A much heavier spreading will be made from
a full truck than from a nearly empty truck 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).

Spray Method

Liquid sludge  can also be sprayed on a site through
spray bars or nozzles. Spraying can be useful in dispers-
ing liquid  sludge on DSD sites,  particularly in remote
areas where public acceptance  is less of a concern;
when sludge characteristics preclude using a sludge
storage lagoon onsite (e.g., because the  sludge solids
at the bottom of the lagoon are difficult to remove even
 Figure 7-30.  Splash plates on back of tanker truck (U.S. EPA, 1978a).
Figure 7-31.  Slotted T-bar on back of tanker truck (U.S. EPA, 1978a).
                                                   134

-------
with air mixing or other processes); or in colder climates
where freezing is a concern (U.S. EPA, 1984c).

Liquid sludge is readily dispersed  by  use of properly
designed  spray equipment.  By spraying  the  liquid
sludge under pressure, a more uniform coverage is
obtained.  Sludge solids must be  relatively small and
uniformly distributed throughout the sludge to achieve
uniform spray and to avoid system clogging.

The main component of a typical  spray system is  a
rotary sprayer (rain gun) to disperse the liquid sludge
over the. site. The sludge, pressurized by a pump, is
transferred from storage to the sprayer via a pipe sys-
tem. Both portable or permanent systems are available,
including (Loehr et al., 1979):

• Solid set, buried or above-ground

• Center pivot

• Side roll

• Continuous travel   ,

• Towline laterals

• Stationary gun

• Traveling gun

Aii  the systems listed, except for the buried solid set
system,  are designed to be portable.  Main lines for
systems are usually permanently buried, providing pro-
tection from freezing weather and heavy vehicles.

The proper design and operation of spray systems for
liquid sludge requires thorough knowledge of the com-
mercial equipment available and its adaptation to use
with liquid sludge. The sludge spray systems in use are
generally associated with DSD sites. It is beyond the
scope  of this  manual to present engineering  design
data; qualified spray system engineers and experienced
spray system manufacturers should be consulted. Fig-
ures 7-32 and 7-33 illustrate two of the spray systems
available.

7.7.3.2   Disposal Methods for Dewatered Sludge
         at DSD Sites

The spreading of dewatered sludge (20 percent solids
or more) is similar to that of solid or semisolid fertilizer,
lime, or animal manure. The dewatered sludge can be
spread with bulldozers,  front end loaders,  graders, or
box spreaders, and then incorporated into the soil by
plowing or discing. The box spreader is commonly used,
but the other types of equipment are often used for high
sludge spreading rates typical of DSD sites. Dewatered
sludge cannot be pumped or sprayed. The spiked tooth
harrows used for normal farming operations may be too
light to adequately bury the sludge;  heavy-duty mine
disks or disk harrows may be required.

The principal  advantages of using dewatered sludge
include reduced sludge  hauling and storage costs and
higher sludge disposal rates (compared to liquid sludge)
per pass of equipment. Potential disadvantages of dis-
posing dewatered rather than liquid sludge at DSD sites
include the need for substantial modification of conven-
tional spreading equipment and  more equipment re-
pairs, compared to many liquid sludge systems.

Figures 7-34 and 7-35 illustrate the specially designed
trucks used  to  spread  dewatered sludge. For small
quantities of dewatered sludge, tractor-drawn conven-
tional farm manure spreaders may be adequate (Loehr
 Figure 7-32.  Venter pivot spray application system (Valmont Ind. Inc.).
                                                   135

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 Figure 7-33.  Traveling gun sludge sprayer (Lindsay Mfg. Co.).
Figure 7-34. 7.2 cubic yard dewatered sludge spreader (Big Wheels, Inc.).
et al., 1979). Surface spreading of dewatered sludge on
tilled  land  is usually  followed by  incorporation  of the
sludge in the soil. Standard agricultural discs or other
tillage equipment pulled by a tractor or bull dozer can
incorporate liquid or dewatered sludge into soil, such as
the disk tiller, disk plow, and  disk harrow shown in
Figures 7-36 and 7-37 (U.S. EPA 1978b).
7.7.3.3   Disposal Methods Not Recommended

Land spreading of sewage  sludge by gravity  irriga-
tion/flooding has generally not been successful where
attempted and is discouraged by regulatory agencies
and experienced designers. Problems with this method
include difficulty in achieving  uniform sludge spreading
                                                   136

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Figure 7-35.  Large dewatered sludge spreader {BJ Mfg. Co.).
Figure 7-36. Example of disc tiller.
 rates; clogging of soil pores; and tendency of the sew-
 age sludge to turn septic with resulting odors.
sewage sludge to DSD sites, as defined in this manual
and in Part 503, is limited by the following factors:
 7.7.4  Sludge Disposal Rates at DSD Sites

 Well  managed DSD projects can be environmentally
 acceptable  even with  high  disposal rates if properly
 sited, designed,  and operated. The disposal rate  of
• Part 503 pollutant limits in sewage sludge for sur-
  face disposal sites if the site does not have a liner
  and leachate collection system. Representative sam-
  ples of sewage sludge must be tested for arsenic,
  chromium, and nickel as required by Part 503 (see
                                                   137

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 Figure 7-37.  Example of disk plow.

   Chapter 3) if the  site does  not have a  liner and
   leachate collection system.

   If monitoring results show that the sludge meets Part
   503 pollutant limits, or if a liner and leachate collection
   system are onsite, then the other factors listed below
   should then also be considered.

 •  The rate  of sludge which can  be disposed during
   each spreading activity while still maintaining aerobic
   conditions in the soil. The method of sludge disposal,
   soil drainage, soil characteristics,  sludge moisture con-
   tent, and climatic conditions all influence this factor.

 •  The number of days during the year when sludge can
   be disposed, as dictated by weather conditions, abil-
   ity of the sludge spreading equipment to operate with
   existing soil conditions,  and equipment breakdown
   and maintenance requirements.

 •  Evaporation rates of sludge liquids.

 Annual sludge disposal rates at  DSD sites range from
 50 to 2,000 T/ac. The higher disposal rates are practiced
 at DSD sites which:

 •  Receive dewatered sludge.

 •  Mechanically incorporate the sludge into the soil.

 •  Have relatively low precipitation.

 • Are not faced with problems of leachate contamination
  of ground water from site conditions or project design.

A conservative approach for calculating sludge disposal
 rates is to match sludge disposal and net soil  evapora-
tion rates. Sludge disposal will generally be  intensive
during warm and dry periods and reduced during wet or
cold periods.
 Net soil evaporation is calculated by the use of:

                     EN = ES - P

                   EN = (fxEL)-P          (Eq. 7-1)
 Where:

 EN = net soil evaporation
 Es = gross soil evaporation
 EL = gross lake evaporation
  P = precipitation
  f = factor expressing the relationship of soil and
      lake evaporation (dimensionless)

 Typically, gross soil evaporation in an area is estimated
 as  a  fraction (e.g., f = 0.70) of the lake evaporation.
 Estimates can be obtained from local agricultural infor-
 mation services. Table 7-16 illustrates the calculation of
 net soil evaporation on a  monthly basis for Colorado
 Springs, Colorado  (Brown and Caldwell, 1979).

 Having estimated  net soil evaporation (EN) for each
 month, the sludge disposal rates on a monthly basis are
 calculated by matching the moisture in  the disposed
 sludge against EN, as shown below:
EN x TS xC
 100-TS
                                          (Eq. 7-2)
Where:
RM = monthly sludge disposal rate (dry mt/ha/mo or
     dry T/ac/mo)
EN = net soil evaporation (cm/mo or in./mo)
TS = total solids content of the sludge ( percent) by
     weight
 C = conversion factor which equals 100 mt/cm or
     113.3T/in.
                                                   138

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Table 7-16. Net Monthly Soil Evaporation at Colorado Springs, Colorado (Brown and Caldwell, 1979)
                                  Gross  Soil                                 Net Soil
                     Month     Evaporation  (cm)*      Precipitatjon (cm)
                                                                        Evaporation (cm)
January
February
March
April
May
June
July
August
September
October
November
December
Annual

.
.
9.16
11.45
13.55
14.69
12.43
9.58
7.34
_
-
78.20
1.80
1.85
3.96
4.85
5.44
5.49
7.62
5.89
3.94
2.82
2.41
1.70
47.78
_
-
-
4.31
6.01
8.06
7.07
6.54
5.64
4.52
-
-
42.15
                      Estimated based on  70 percent lake  evaporation.
                    t  Gross soil  evaporation less precipitation.
                    #  1 in * 2.54 cm.
Table 7-17 shows monthly sludge disposal rates for the
Colorado Springs site based on a sludge with a 4.85
percent solids content and the net monthly soil evapo-
ration  rates shown in Table  7-16. Sample calculations
for April would be:
         Metric
        English
                4.31 x 4.85x100
                    100-4.85
= 22 m/ha
                1.70x4.85x113.3
                    100-4.85
 = 9.8 T/ac
Referring to Table 7-17, an annual average total of 215
mt/ha (95.8 T/ac) dry weight of sludge could be disposed
at this site based on net soil evaporation.

The use of net soil evaporation as a basis for calculating
sludge disposal rates at DSD sites is conservative since
it makes no allowance for moisture removal from the
sludge through infiltration into  the soil. If infiltration is
allowed,  sludge disposal rates at DSD sites  can be
calculated by the following equation:

                     (EN + l)xTSxC
                 M~    100-TS

Where:

I = infiltration rate (cm/mo or in./mo)

all other terms as in previous equations

 7.7.5  Drying Periods Between Sludge
        Spreading Activities

Drying (rest) periods between each sludge spreading
activity allow the soil to return  to its  natural aerobic
condition. Disposal should be scheduled to prevent ex-
cessive  moisture in the  soil for long  periods and to
minimize odors and the breeding of vectors.
                                                       Table 7-17.  Monthly Sludge Disposal Rates at Colorado
                                                                  Springs, Colorado, DSD Site (Brown and
                                                                  Caldwell, 1979)
                                                                                Monthly Application Rate
                                                          Month
                                                                           (dry mt/ha)t
                                                                (dry T/acV
January
Feoruary
March
April
May
June
July
August
September
October
November
December
m
-
•
22. 0
30.7
41.1
36.1
33.4
28.8
23.1
.
-
_
-
-
9.8
13.7
18.3 '
16.1
14.8
12.8
10.3
-
'
                                                        Annual
                                                                              215.0
                                                                                                    95.8
                                                        * Total solid content in the sludge is assumed to be 4.85 percent.

                                                        t Using Equation (7-2) and data from Table 7-16.
                                                        It is difficult to provide exact guidelines for the length of
                                                        the drying period because numerous factors are in-
                                                        volved, including:

                                                        • Quantity and moisture content of sludge disposed.

                                                        • Method of sludge disposal.

                                                        • Net soil evaporation  rate and precipitation occurring
                                                          during the days following disposal.

                                                        • Soil texture and infiltration rate.

                                                        Generally, if dewatered sludge is disposed and/or the
                                                        sludge is incorporated into the soil during disposal, dry-
                                                        ing periods  between each spreading activity can  be
                                                        short (2 to 3 days),  providing the weather is favorable.
                                                        When liquid sludge is spread to the soil surface without
                                                        soil incorporation, the drying  periods should be longer
                                                     139

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  (5 to 20  days), depending upon the quantity applied,
  topography, soil properties, and weather. Figure 7-38
  shows suggested periods between each sludge spread-
  ing activity as a function of the type of sludge (liquid or
  dewatered), whether the sludge is incorporated into the
  soil, and  disposal rate. This figure is based on experi-
  ence at a limited number of DSD sites reviewed and is
  provided for general guidance only.

  Aerobic conditions in the soil are more easily maintained
  by lighter disposal of sludge at more frequent intervals.
  For example, referring to the upper curve in Figure 7-38
  for liquid  sludge that is not incorporated into the soil,
  disposal of 11 mt/ha  (5  T/ac)  at 7-day intervals are
  generally  preferable to disposal of 31 mt/ha (14 T/ac) at
  20-day intervals. The heavier sludge disposal  is more
  likely to cause anaerobic soil conditions conducive to
  odors and vector breeding.

  7.7.6  Land Area Needs

 Availability of sufficient land area is an essential consid-
 eration in  selecting a DSD site.  Oftentimes, DSD sites
 are located on land owned by a municipality. The high
 sludge disposal  rates at DSD sites minimize  land re-
 quirements (compared to land application options, such
 as spreading sludge on agricultural land) by maximizing
 sludge disposal rates per hectare.

 Land area needs for a DSD site include land needed for
 sludge disposal, sludge storage, buffer areas, surface
 runoff control, and supporting facilities.  Each of these
 needs is discussed below. The prudent designer will
 incorporate appropriate factors into the design to allow
 for possible future expansion.

 7.7.6.1    Land Needed for Sludge Disposal

 Once the acceptable sludge disposal (spreading) rate
 has been determined (as discussed  in  Section 7.7.5
 above), a simple calculation can be used to define the
 area needed for sludge disposal.  The  calculation in-
 volves dividing the annual disposal/spreading rate into
 the total estimated quantity of sludge (both present and
 future) to be disposed annually, as shown below:
 Area required =
 Maximum estimated amount of sludge be disposed of annually (dry weight)
       Annual disposal/spreading rate (dry weight/unit area)

 7.7.6.2   Land Needed for Sludge Storage

 Sludge storage is virtually always required at DSD sites
 because adverse weather  or other factors prevent the
 continuous spreading of sludge at the site. Storage may
 be located at the POTW, at the DSD site, or both. At a
 minimum, the sludge storage facilities should have suffi-
 cient capacity to retain all sludge generated during non-
spreading periods.  Liquid sludge is  typically stored in
 lined lagoons or metal tanks. Dewatered sludge is typi-
cally stored by mounding in areas protected from runoff.
Odor controls are often needed for sludge lagoons, as
                      20
                      15 -
                   ซ
                 gs
                 S.1-
                jd eo
                 in"0
                 six:
                3
                       5 -
                                                  10
                                                               IB
                                                                            20.
                                Tons/acre of sludge disposed, dry weight, each spreading activity
                                Metric conversion - 0.446 tons/acre = 1 metric ton/ha
Figure 7-38.  ^Siested drying days between sludge activities at DSD sites for average soil conditions and periods of net evaporation
                                                   140

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discussed in the section on "Aesthetics at DSD Site" in
Chapter 9.

If sludge is stored for less than two years, the area is
not considered to be final disposal  and is not covered
under Part 503. If, however, sludge is placed on an area
of land for more than two years, that land area is con-
sidered a final surface disposal site, and, in addition to
the area on which sludge is spread on the land, this
"storage" area  must also meet the Part  503 surface
disposal  requirements. Often the  relevant  regulatory
agency will stipulate the minimum number of days for
which sludge storage must be provided at a site (e.g.,
one-month or two-month storage).

One method for estimating the storage capacity needed
for sewage  sludge  involves estimating the  maximum
volume of sewage sludge to be disposed each day at
the  DSD site,  the  percentage of solids the sludge
contains, and the number of storage days to be pro-
vided. These estimations should include  climatic and
soil considerations (discussed later in this chapter) and
a s'afety factor. The project designer should increase the
minimum storage requirement by a safety factor of 20 to
50 percent to cover years  with unusual weather and
other contingencies. An example  calculation for this
approach is:

Assuming:

• The average rate of dry sludge solids to be disposed
   at the DSD site is 589 kg/day (1 ,300 Ib/day).

• The sewage sludge contains 5 percent solids on the
   average.

• 100 days of storage are to be provided.
          589kg/day   = „
          0.05<% solids) -••
                                of liquid sludge to
                         be stored.
          11,778 kg/day = 11,778 liters (l)/day (3,118
                         gal/day) of liquid sludge to
                         be stored.
 11,788 I/day x 100 days = 1.2 mil I (312,000 gal) of
                         storage required.

 A more sophisticated method of calculating sludge stor-
 age needed is to prepare a mass flow diagram of pro-
 jected cumulative sludge generation and disposal at the
 DSD site, as shown in Figure 7-39. The figure shows
 that the minimum sludge storage requirement for the
 system is approximately 1.2 x 106 gal (4.54 x 106 I),
 which represents 84 days of sludge volume storage.

 Even more  accurate approaches can be used to calcu-
 late required sludge storage volume. For example, if
 open lagoons are used for sludge storage, the designer
 can calculate volume additions resulting from precipita-
tion and volume subtractions resulting from evaporation
from the storage lagoon surface.

Once the  necessary storage volume has been estab-
lished, the land  area required for either liquid sludge
lagoons or dewatered sludge stockpiles can be deter-
mined based on depth,  height, freeboard, berm  con-
struction area, etc. As a rough approximation, the land
area  required equals  three times the volume of the
sludge to  be stored divided by the depth (or height) of
the material stored. For example, assume that one mil-
lion L (35,310 ft3) of liquid sludge storage is required and
the liquid depth of the lagoon is 3 m (9.8 ft). The approxi-
mate area required equals 1,000 m2  (10,800 ft2).

Storage capacity can be provided by:

• Lagoons

• Tanks (open top or enclosed)

• Digesters

• Stockpiles

These sludge storage methods are summarized briefly
below. For a more detailed discussion on sewage sludge
storage options, see EPA's Process  Desit/n Manual for
Sludge Treatment and Disposal (U.S. EPA, 1979).

Lagoons are usually the  least expensive way to  store
sludge. With proper design, lagoon  detention will  also
provide additional stabilization of the  sludge and reduce
pathogens. Several types,of lagoons have been  used
for sludge storage, including:

• Facultative sludge lagoons

• Anaerobic  liquid sludge lagoons

• Aerated storage basins

• Drying  sludge lagoons

Various types of tanks also can be used to store sludge.
In most cases, tanks are an integral part of the sludge
treatment processes  of  the  POTW and their design
includes storage capabilities. Three common types of
tanks used for sludge storage include:

•  Imhoff and community septic tanks

•  Holding tanks

•  Unconfined hoppers and bins

Many sewage treatment plants do  not have  separate
sludge retention capacity but rather rely on portions of
the digester volume for storage. When available, an un-
heated sludge digester may provide short-term storage
capacity.  In anticipation of periods when sludge cannot
 be disposed on the DSD site, digester supernatant with-
drawals can be accelerated to provide storage for sev-
 eral weeks of sludge volume (U.S. EPA, 1978a).
                                                   141

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           13
            O
              6.0-t
              5.0'
_1  4..0-
U

UJ
a
a
>  3.fl-
at

=i
            JU 2.0-
            <

            SC
            3
            o i .0-
                                                        TOTAL  ANNUAL  SLUDGE
                                                        VOLUME GENERATED
                                        LINE A
                                        CUM  XILATIVE SLUDGS
                                        VOLUME GENERATED  *x'
                                        BY  THE POTW
                          SLUDGE
                          STORAGE
                          VOLUME
                                                         L
                                                               LINEB
                                                               CUMULATIVE SLUDGE
                                                               VOLUME SPREAD ON
                                                               THE DSD SITE (S)
                                                       LINE C. SAME  SLOPE
                                                       AS  LINE A, LOCATE
                                                       TANGENT TO LINE B
                                            M     J

                                             MONTHS
                      METRIC  CONCESSION
                         : GAL ป 3.78  L
Figure 7-39. Example of mass flow diagram using cumulative generation and cumulative sludge spreading to estimate storage
           requirements at a DSD site.
Stockpiling is a temporary storage method for sludge
that has been stabilized and dewatered or dried to a
concentration (about 20 to 60 percent solids) suitable for
mounding with  bulldozers  or loaders. The sludge  is
mounded into stockpiles 2 to  5 m (6 to  15  ft) high,
depending on the quantity  of sludge and the available
land area. Periodic turning of the sludge helps to pro-
mote drying and maintain aerobic conditions. The proc-
ess is most applicable in arid and semiarid regions, unless
the stockpiles are covered to protect against rain. Enclo-
sure of stockpiles may be necessary to control runoff.


7.7.6.3  Land Needed for Buffer Zone

If the DSD site is meeting the Part 503 pollutant limits
for arsenic,  chromium, and nickel at  surface disposal
sites (rather than having a liner and leachate collection
system onsite to meet this Part 503 requirement), then
the distance of the actively used portions of the DSD site
from the property boundary will determine the specific'
pollutant limits that must be met (see Chapter 4).
                                           The desired width of an acceptable buffer zone will vary,
                                           depending on surrounding land use and the potential for
                                           odor, dust, and noise resulting from the site. A minimum
                                           buffer of 150 m (500 ft) is suggested around any DSD
                                           site. A minimum buffer of 600 m (2,000 ft) is suggested
                                           around  DSD  sites when  one or more of the following
                                           conditions will exist:

                                           • Liquid sludge is stored at the site in open lagoons.

                                           • Liquid sludge is spread on the soil surface and is not
                                             quickly incorporated by discing.

                                           • Liquid sludge is sprayed using a wide coverage spray
                                             device.

                                           • Residential dwellings or  other  heavily used public
                                             areas are adjacent to the DSD site.

                                           • Sludge disposal rates are high  and it is anticipated
                                             that anaerobic soil conditions will periodically result.

                                           While difficult to quantify, the desirable width of a buffer
                                           zone is also a function of the size of the operation (e.g.,
                                                   142

-------
volume of sludge disposed and the disposal area). The
larger the operation, the more buffer area is desirable
simply because the magnitude of potential nuisance to
surrounding property is greater.

7.7.7  Proximity to Community Infrastructure

Another important consideration in designing a DSD site
is its location relative to local infrastructure, including:
• Availability of a sewerage system to manage surface
  runoff and/or leachate.
• Proximity to a treatment plant to maintain reasonable
  sludge transportation costs.
• Accessibility to transport  (e.g., roads and/or pipe-
  lines).

 7.7.8  Climate Considerations
 Information on local climatic conditions is used in many
 aspects of the DSD site design,  including:
 • Designing surface runoff collection, storage, and con-
  trol  structures.
 • Determining necessary sludge storage capacity.
 • Determining  the  area  requirements  for  sludge
   spreading.
 • Determining any necessary leachate collection and
   storage systems.
 The designer should obtain the  following historical cli-
 matic information for the  past 20 years:
 • Precipitation, by month and year (average and maxi-
   mum).
 • 25-year storm intensity (for which control is required
   by  Part 503);  also 50- and 100-year storms.
 • Evaporation rate from water  surface, by month and
   year (average and minimum).
 • Annual number of days of precipitation over 0.3 cm
   (0.1 in) (average and maximum).
 • Annual number of days below freezing (average and
   maximum).
  In addition, it is useful to know the local evaporation rate
 from  soils (usually about 70 percent of the  rate from
 water surfaces). This information may be available from
  local university agricultural extension services or federal
  agencies. Generally, a site located in  a temperate, arid
  climate is preferable for  its high net evaporation.

  7.7.9  Design Considerations At Beneficial
         DSD Sites
  Some DSD sites are considered beneficial DSD sites
  because vegetation is grown on the site. The Part 503
regulation states that no crop production or grazing can
be conducted at any surface disposal site,  including
beneficial DSD sites, unless the  owner/operator can
demonstrate  to the permitting  authority that, through
management practices, public health and the environ-
ment will be protected from any reasonably anticipated
adverse  effects  of pollutants in sewage sludge when
crops are grown or animals are grazed. Growing vege-
tation at a beneficial DSD site  has both major advan-
tages and disadvantages, as discussed in Table 7-18.
Beneficial DSD sites are discussed further in Chapter 9.

7.8   Environmental Safeguards at
       Surface Disposal Sites

Ground-water protection is the  most difficult and costly
environmental control measure required at many sew-
age sludge surface disposal sites. Additionally, contami-~
nation of surface water and methane gas buildup must
be avoided. Design concepts that minimize or prevent
adverse environmental impacts from surface drainage
and methane gas migration at surface disposal sites are
presented below. Other environmental controls are dis-
cussed in Chapter 8, Operations, since their control is
more a function of operation than design.

 7.8.1  Leachate Controls

 Leachate can be generated simply from the excess
 moisture in the  sewage sludge received at a surface
 disposal facility.  Rainfall on the surface of the disposal
 unit can add a limited amount of water to the interred
 sludge.  The  surface  of  the disposal unit  should be

 Table 7-18. Advantages and Disadvantages of Dedicated
           Beneficial Use Sites
 Advantages      1.  If surface soil is "tight" and drains poorly,
                   the plant root structure may improve soil
                   drainage.
                2.  Plants will enhance water removal through
                   evapotranspiration. •

                3.  Plants will help to reduce surface runoff
                   volume from precipitation.

                4.  Plants will take up a portion of the
                   nitrogen, metals, and other sludge
                   constituents applied by incorporating them
                   during growth.  If the plants are harvested
                   and used or disposed in a controlled
                   manner, the constituents incorporated in
                   the plants are removed from the site.

                5. The DSD site will more closely resemble a
                   normal farming operation and be more
                   visually pleasing to the public.

                 6. Some of the sludge nutrients will be
                   recycled into vegetation and may serve as
                   a positive public relations factor to many
                   citizens.
                 7. Harvesting of the plants and their sale may
                   provide a monetary return.
                                                     143

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 Table 7-18.  Advantages and Disadvantages of Dedicated
            Beneficial Use Sites (continued)
 Disadvantages    1. Sludge spreading scheduling is more
                   complex since it usually must operate
                   around the seeding, cultivation, and
                   harvesting operations. Planted areas may
                   be "off limits" for high rate sludge disposal
                   during many months, often the best
                   months for sludge disposal from an
                   operations viewpoint.
                 2. Planting, cultivation, and harvesting of  .
                   plants can be labor and equipment
                   intensive. Capital equipment and operating
                   costs are increased over those for a DSD
                   site that does not grow and harvest
                   vegetation.  Management is more complex
                   since agronomic considerations are added
                   to the primary mission of sludge
                   management.
                 3. The area required for a DSD  site may be
                   larger with vegetation involvement than for
                   a project with no vegetation.
                 4. Planted areas attract animals that could
                   become a nuisance or serve as vectors.
                 5. Planted areas may result in more
                   unauthorized public entry, e.g., children
                   climbing fences.
                 6. Harvested plants may contain metal
                   concentrations too high for human or
                   animal consumption necessitating
                   controlled disposal.
                7. After years of heavy sludge disposal, the
                   soil may become phytotoxic to plants
                   effectively ending any potential for
                   agricultural operations at the site.
 sloped enough to cause most of the rainfall to drain.
 Other stormwater runoff must be diverted around the
 disposal  unit, and  the unit must  be located above
 historically high ground-water elevations. These positive
 controls will minimize the quantity of leachate generated.

 Leachate may enter into the water  system essentially
 through two pathways:

 • Percolation  of the  leachate, laterally or vertically,
  through soil into the ground-water aquifers.

 • Runoff  of leachate outcroppings into surface waters.

 Careful site selection and attention to design considera-
tions can prevent or minimize leachate contamination of
 ground water and surface water. The control of leachate
 may be accomplished through:

• Natural conditions and attenuation (Section 6.4 and 6.5).

• Imported  soils or soil amendments used as  liners
  and/or cover (Section 7.5.6.1).

• Membrane liners (Section  7.5.6.2).

• Collection and treatment (Section  7.5.7).
  7.8.2  Run-on/Runoff Controls

 The purpose of a run-on control system is to collect and
 redirect surface waters to minimize the amount of sur-
 face water entering active sewage sludge units. Run-on
 control can be accomplished by constructing berms and
 swales above the filling area that will collect and redirect
 the water to the stormwater control structures.

 Surface water management also is necessary at surface
 disposal sites to minimize erosion damage to earthen
 containment structures.  Design  of  a surface water
 management system requires a knowledge of  local
 precipitation patterns, surrounding topographic features,
 geologic conditions, and facility design.  Surface water
 management systems do not  have to be expensive or
 complex to be  effective. The equipment and materials
 used for construction of the surface water management
 system are the same as those used for general earth-
 work and foundation construction. Construction may in-
 clude excavation of a  series of shallow channels  to
 direct surface water flow, or in some cases, installation
 of basins  to retain  rainfall accumulation from sudden,
 intense storms. Surface water management systems
 are required for all surface disposal sites. This section
 provides a general discussion of design criteria for those
 systems  and describes the types  of system compo-
 nents.  For more information on the materials and  con-
 struction techniques that may be employed to control
 run-on/runoff at surface disposal sites, see the reference
 U.S. EPA(1988a).

 The management practices  of the Part 503 regulation
 require the owner/operator of surface disposal units to
 operate and maintain runoff and run-on management
 systems capable of collecting and controlling at least the
 water volume resulting from a 24-hour, 25-year storm.

 7.8.2.1  Design Overview

 The standard design approach for a surface water con-
 trol system is to: ,

 •  Identify the intensity of the design storm.

 •  Determine the peak discharge rate.

 •  Calculate the runoff volume during peak discharge.

 •  Determine the control system design criteria and the
   required capacity for the control systems.
 •  Design the control system.

 Identify Design Storm

 Information on the 24-hour, 25-year recurring storm  can
 be obtained from Technical Paper 40 Rainfall Frequency
Atlas of the United States for Durations from 30 Minutes
 to 24 Hours and Return Periods from  1 to 100 years,
prepared by the  Weather Bureau under the Department
of Commerce.
                                                    144

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Determining Peak Discharge Rate/Calculating Runoff

The two methods commonly recommended by EPA for
use in designing surface water management structures
are the Soil Conservation Service (SCS) method and
the rational method.

SCS  Method. A method that is most often appropriate
for estimating run-on/runoff and peak discharge rate
from a storm's rainfall is the SCS method. This method
was originally designed to determine runoff volumes for
small agricultural watersheds  where insufficient long-
term  stream flow and precipitation data had been col-
lected, but where soil types, topography, vegetative
cover, and agricultural practices had been documented.
The SCS method estimates runoff volume from accumu-
lated  rainfall and then applies the runoff volume to a
simplified triangular unit hydrograph for peak discharge
estimation and total runoff hydrograph  (U.S. EPA,
1993b). A discussion of the development and use of this
method is available in the reference U.S. Department of
Agriculture, Soil Conservation  Service (1986).

national Method. The rational method can be applied
when determining peak discharge rates for significantly
urbanized areas with largely impervious surface covers.
The  method is based on  the premise that maximum
runoff resulting from steady, uniformly intense precipita-
tion will occur when the  entire watershed, upstream of
the site location, contributes to the discharge (U.S. EPA,
 1985a). The method generally is used for areas of less
than  200 acres. A discussion of the rational method can
 be found in U.S. EPA (1988a).

 Control System Structures

 Surface water management plans can  incorporate sev-
 eral structures, both temporary and permanent,  into the
 system design. Table 7-19 provides a list of the most
 frequently used structures.

 Dikes/Berms.  Dikes and  berms  are  well-compacted
 earthen ridges or ledges constructed immediately  upslope
 from or along the perimeter  of the intended  area of
 protection. Atypical dike design is shown in Figure 7-40.
 Dikes are intended to provide short-term protection of
 critical areas by intercepting storm runoff and diverting
 the flow to natural  or man-made  drainage  channels,
 man-made outlets, or sediment basins. Typically, dikes
 and  berms should be expected to maintain their integrity
 for about 1 year, after which they should be rebuilt. Dikes
 are  generally  classified into two  groups:  interceptor
 dikes, designed to reduce slope length; and diversion
 dikes, designed to  divert surface flow and  to reduce
 slope length. Dikes can also  prevent mixing of incom-
 patible wastes and can  reduce the amount of leachate
 produced in a landfill cell by diverting the water available
 to infiltrate the soil cover. Due to their temporary nature,
dikes and berms are designed for runoff from no. larger
than a 5-acre watershed (U.S. EPA, 1985b).

Swales, Channels, and Waterways. Channels are exca-
vated ditches that are generally wide and shallow with
trapezoidal, triangular, or  parabolic cross sections. A
typical channel design is shown in Figure 7-41. Diver-
sion channels are used primarily to intercept runoff or
reduce slope length. Channels stabilized with vegetation
or stone rip-rap are used to collect and transfer diverted
water off site or to onsite storage or treatment. Applica-
tions and limitations of channels and  waterways differ
depending upon their specific design (U.S. EPA, 1988a).

Swales are placed  along the perimeter of a  site to
keep offsite runoff from entering the site and to carry
surface runoff from a land disposal unit. They are distin-
guished from earthen channels by side slopes that are
less steep and have vegetative cover for erosion control
(U.S. EPA, 1985b).
The specific design for channels, swales,  and water-
ways must consider local drainage patterns, soil  perme-
ability, annual  precipitation,  area land use,  and other
pertinent characteristics of the contributing watershed.
To comply with the Part 503 regulation, channels and
waterways should accommodate the maximum rainfall
expected in a 25-year period. Manning's formula for
steady uniform flow in open  channels  is used to design
channels and waterways (U.S. EPA, 1985b).
 Terraces. Terraces are embankments constructed along
the contour of very long or very steep slopes to intercept

Table 7-19.  Surface Water Diversion and Collection
           Structures (U.S. EPA, 1988a)
            Technology
                             Duration of Normal Use
     Dikes and berms
     Channels (earthen and CMP)
     Waterways
     Terraces and benches

     Chutes
     Downpipes
     Seepage ditches and basins
     Sedimentation basins
 Temporary
 Temporary
 Permanent
Temporary and
 permanent
 Permanent
 Temporary
 Temporary
 Temporary
  Cut or fill slope
                                             Flow
                            Existing ground

 Figure 7-40. Typical temporary diversion dike (U.S. EPA, 1988a).
                                                    145

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                                            Parabolic cross-section
Figure 7-41.  Typical channel design (U.S. EPA, 1988a).

and divert flow of surface water and to control erosion
of slopes by reducing slope length.  A typical terrace
design is shown in Figure 7-42. Terraces may function
to hydrologically isolate sites, control erosion of cover
materials on sites that  have been capped,  or collect
sediments  eroded from disposal areas. For disposal
sites  undergoing final grading,  construction terraces
may be included as part of the site closure plan (U.S.
EPA, 1985b).

Chutes and Downpipes. Chutes and  downpipes are
usually temporary structures that can play an important
role in preventing  erosion while monofill and  surface
impoundment covers are "stabilizing" with vegetation. A
typical chute design is shown in Figure 7-43. Chutes are
excavated earthen channels lined with non-erodible ma-
terials such as bituminous concrete or grouted rip-rap.
Downpipes  are constructed of rigid piping or flexible
tubing and installed with prefabricated inlet sections. As
a general rule, chutes should not be used when hydrau-
lic heads are expected to be more than 18 ft (U.S. EPA,
1988a). Downpipes should not be used when the drain-
age basin is estimated to be larger than 5 acres (U.S.
EPA, 1985b).

Seepage Basins and Ditches. Seepage  basins  and
ditches are used to discharge water collected from sur-
face  water  diversions, ground-water pumpings, or
leachate treatment. They also may be used as part of
an in situ treatment process to force treatment reagents
into the subsurface. A typical seepage  basin design is
shown in Figure 7-44. They are most effective in highly
permeable  soils  where  recharge can occur. Typically,
they are used in areas with shallow ground-water tables.
Seepage ditches distribute water over a larger area than
achievable with basins. They can be used for all soil
where permeability exceeds about 0.9 in. per day (U.S.
EPA, 1985b).

A seepage basin typically consists of the actual basin, a
sediment trap, a bypass for excess flow, and an emer-
gency overflow. A considerable amount of recharge oc-
curs through the sidewalls of the basin,  and therefore it
is preferable that these be constructed of pervious ma-
terial such as packed gravel (U.S. EPA, 1985b).
              Ditch
                                       Ditch
Figure 7-42.  Typical terrace design (U.S. EPA, 1988a).

Sedimentation Basins. Sedimentation basins are used
to retard surface water flow such that suspended par-
ticulates can settle. Sedimentation basins serve as the
final step in the control  of diverted, uncontaminated
surface runoff, prior to discharge. Atypical basin design
is shown in Figure  7-45. Basins are especially useful in
areas where surface  runoff  has a high silt or sand con-
tent. The major components include a principal and
emergency spillway, an anti-vortex device, and the ba-
sin. The principal spillway consists of a  vertical pipe or
riser joined to a horizontal pipe that extends through the
dike and has an outlet beyond the impoundment. The
riser is topped by the anti-vortex device  and trash rack,
which improves the flow of  water into the spillway and
prevents floating debris from  being carried  out  of the
basin  (U.S. EPA, 1985b).

7.8.3   Explosive Gases Control

Under the Part 503  regulation,  surface disposal sites
that cover active sewage sludge units (either daily or at
closure) must limit  the concentration of methane  gas in
the air in any structure within  the site, and in the air at
the property  line  of the disposal site (see Section
7.2.1.3).

The accumulation  of methane gas  in surface disposal
structures can potentially result in fire and explosions
that can endanger employees, users of the disposal site,
and occupants of nearby structures, or  cause damage
to containment structures. These hazards are prevent-
able through monitoring and through corrective  action
                                                  146

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                                                    Top of earth dike and top of lining
                                                                    Slope
                          varies, not steeper than 1.5:1
                        not flatter than 20:1
                        Undisturbed soil
                        or compacted fill
                             •              Place layer of
                                   ,.   ;    sand for drainage
                :'.'.'•;.    .••,'"'•     under outlet as
                     ;.                     shown for full
                --;":-          ••''.          width of structure

Figure 7-43.  Typical paved chute design (U.S. EPA, 1988a).
                                                                 Seepage basin
                                 Bypass

Figure 7-44.  Typical seepage basin design (U.S. EPA, 1988a).
•4-f/ Jl

ment tra

	 1
P t


* . -— --' 	 • •

	 , 	 . 	 c
T
Overflow
                       Anti-vortex Device


                     Water Surface (design)
                    Emergency Spillway Crest
Anti-seep Collars


               Pipe Conduit or Barrel
                                                              Principal Spillway
                                                                                                  Free Outlet
                                                   EMBANKMENT

Figure 7-45.  Typical sedimentation basin design (U.S. EPA, 1988a).
                                                             147

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 should methane gas levels exceed specified limits in the
 facility structures (excluding gas control or recovery sys-
 tem components), or at the facility property boundary.

 To implement an appropriate plan for routine monitoring
 of methane  in order to demonstrate compliance with
 allowable methane concentrations, the characteristics of
 gas production and migration at a disposal site should
 be understood. See the reference U.S. EPA (1993b) for
 a complete discussion of the characteristics of methane
 gas production.

 7.8.3.1  Gas Monitoring

 To demonstrate compliance with the Part 503 regulation,
 the owner/operator must sample air within facility struc-
 tures where gas  may  accumulate  and in soil at the
 property boundary. Other monitoring methods may  in-
 clude: sampling gases  from probes within the surface
 disposal unit or from within the leachate collection sys-
 tem; or sampling gases from monitoring probes installed
 in soil between the surface disposal unit and either the
 property boundary or structures where gas migration may
 pose a danger. A typical gas monitoring probe installa-
 tion  is depicted in Figure 7-46 (U.S.  EPA, 1993b).

 The frequency of monitoring should  be sufficient to de-
 tect  methane gas migration based on subsurface condi-
 tions and the changing conditions within the disposal
 unit such as partial or complete capping, unit expansion,
 gas  migration control system operation or failure,  con-
 struction of new or replacement structures, and changes
 in landscaping or land use practices. The rate of meth-
 ane gas migration as a result of these anticipated changes
 and  the site-specific conditions,  provides the  basis for
 establishing a monitoring frequency (U.S. EPA, 1993b).

 The  number and  location of gas probes is  also site
 specific and highly dependent on subsurface conditions,
 land use, and location and design of facility structures.
 Monitoring for gas migration should be within the more
 permeable strata. Multiple or nested  probes are useful
 in defining the vertical  configuration  of the migration
 pathway. Structures with basements or crawl spaces are
 more susceptible  to  landfill gas infiltration.  Elevated
 structures are typically not at risk (U.S. EPA, 1993b).

 Measurements are usually made in the field with a portable
 methane meter, explosimeter, or organic vapor analyzer.
 Gas  samples also may be collected in glass  or metal
 containers for laboratory analysis. Instruments with scales
 of measure in "percent  of LEL" can be calibrated and
 used to detect the presence of methane. Instruments of
 the hot-wire Wheatstone bridge type (i.e., catalytic com-
 bustion) directly measure combustibility of the  gas  mix-
ture withdrawn from the probe. The thermal conductivity
type meter is susceptible to interference as the relative
 gas composition—and, thus, the thermal conductivity—
changes. Field instruments should be calibrated prior to
                                  PVC caps with
                                  petcocks

                                  Protective casing
                                  with lock
                                  BentonKe ioil seal
                                  BentonKe seal

                                  11nch PVC pipe

                                  1/2 inch PVC pipe
                                  11nch perforated
                                  PVC pipe
                                 Gravel backfill
                                 Bentonlte seal


                                 Sand and gravel
                                 Probe screen
Figure 7-46.  Typical gas monitoring probe (U.S. EPA, 1993b).

measurements and  should be rechecked  after each
day's monitoring activity (U.S. EPA, 1993b).

Laboratory measurements with organic vapor analyzers
or gas chromatographs may be  used to confirm the
identity and concentrations of gas. In addition to meas-
uring gas composition, other indications of gas migration
may be observed. These include odor (generally described
as either a "sweet" or a rotten egg [hydrogen sulfide, or
H2S] odor), vegetation damage, septic soil, and audible
or visual venting of gases, especially in standing water.
Exposure to  some  gases can cause headaches and
nausea.

If methane concentrations are in excess of 25  percent
of the LEL in facility structures or exceed the LEL at the
property boundary, the danger of explosion is imminent.
Immediate action must betaken to protect human health
from  potentially explosive conditions.  All personnel
should be evacuated from the area immediately.  Venting
the  building upon exit (e.g., leaving the door open) is
desirable but should not replace evacuation procedures.
See Section 10.4.4 for additional information on meth-
ane monitoring.

7.8.3.2   Gas Control Systems

Gas from covered surface disposal units may vent natu-
rally or be purposely vented to the atmosphere by verti-
                                                  148

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cal and/or lateral migration controls. Systems used to
control or prevent gas  migration are categorized as
either passive or active systems. Passive systems pro-
vide preferential flow paths by means of natural  pres-
sure, concentration,  and  density  gradients.  Passive
systems are primarily effective in controlling convective
flow and have limited success controlling diffusive flow.
Active systems are effective in controlling both types of
flow. Active systems use mechanical equipment to direct
or control landfill gas by providing negative or positive
pressure gradients. Suitability of the systems  is based
on the design and age of the surface disposal  unit, and
on the soil, hydrogeologic, and  hydraulic conditions of
the facility and surrounding environment.  Because of
these variables, both systems have had varying degrees
of success (U.S. EPA, 1993b).

Passive systems may be used in conjunction with active
systems. An example of this may be the use of a low-
permeability passive system for the closed portion of a
monofill unit (for remedial purposes) and the installation
of an active system in the active portion of the monofill
unit (for future use).

Selection of construction materials for either type of gas
control system should consider the elevated tempera-
ture conditions within a covered surface disposal unit as
compared to the ambient air or soil conditions in which
gas control system components are  constructed. Be-
cause ambient conditions  are  typically cooler, water
containing corrosive waste constituents  may be ex-
pected to condense. This condensate should be consid-
ered in selecting construction materials. Provisions for
managing this condensate should  be incorporated to
prevent accumulation and possible  failure of the collec-
tion system.

Passive Systems

Passive gas control systems rely on natural  pressure
and convection mechanisms to vent methane gas to the
atmosphere. Passive systems typically use "high-per-
meability" or "low-permeability"  techniques at a site,
either singularly or in  combination. High-permeability
systems use conduits such as ditches, trenches, vent
wells, or perforated vent pipes surrounded by coarse soil
to vent landfill gas to the surface and the  atmosphere
(see Figure 7-47). Low-permeability systems block lat-
eral migration through barriers such as synthetic mem-'
branes and high-moisture-containing fine-grained soils
(U.S. EPA, 1993b).

Passive systems may be incorporated into a surface
disposal unit or may be used for remedial or corrective
purposes at both closed and active surface  disposal
units. They may be installed within a surface disposal
unit along the perimeter, or between the unit and the
disposal facility property boundary. A detailed discussion
of passive systems for remedial or corrective purposes
may be found in U.S. EPA (1985b).

A passive system may be  incorporated into the final
cover system of a surface disposal unit closure design
and may consist of perforated gas collection pipes, high-
permeability soils, or high-transmissivity geosynthetics
located just below the low-permeability gas and hydrau-
lic barrier or infiltration layer in the cover system. These
systems may be connected to vent pipes that vent gas
through the cover system  or that are connected to
header pipes located along with perimeter of the surface
disposal unit. The methane gas collection system also
may be connected with a leachate collection system to
vent gases in the headspace of leachate collection pipes
(U.S. EPA, 1993b).

Some problems have been associated with passive sys-
tems. For example, snow and dirt  may accumulate in
vent pipes, preventing gas from venting. Vent pipes at
the surface are also susceptible to  clogging by vandal-
ism.

Active Systems

Active gas control systems use mechanical  means to
remove gas from  surface disposal  units and consist of
either positive pressure (air injection) or negative pres-
sure  (extraction)  systems.  Positive pressure systems
induce a pressure greater than the pressure of the  mi-
grating gas and drive the gas out of the soil  and/or back
to the surface disposal  unit in  a  controlled manner.
Negative pressure systems extract gas from  a surface
disposal unit by using a blower to pull gas out of the unit.
Negative pressure systems are more commonly used
because they are more effective and offer more flexibility
in controlling gas migration. The gas may be recovered
for energy conversion, treated, or combusted in a flare
system. Typical components of a flare system are shown
in Figure 7-48. Negative pressure systems may be used
as either perimeter gas control systems or interior gas
collection/recovery systems. For more  information  re-
garding negative pressure gas control systems, refer to
U.S. EPA(1985b).

An active gas extraction well is depicted in Figure 7-49.
Gas extraction wells may be installed within the surface
disposal unit or, as depicted in Figure 7-50a and Figure
7-50b, perimeter  extraction trenches could  be used.
One  possible configuration of an  interior  gas collec-
tion/recovery system is illustrated in Figure 7-51. The
performance of active systems is  not  as  sensitive to
freezing or saturation of cover soils as  that of passive
systems. Although active gas systems are  more effec-
tive  in withdrawing gas from a surface disposal unit,
capital, operation, and maintenance costs of  such sys-
tems will be higher as these costs  can  be  expected to
continue throughout the  post-closure period. At some
future time, owners and operators may wish to convert
                                                  149

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                                                Gas Vent
                                                                               Top Layer

                                                                               Low-Permeability Layer

                                                                               Vent Layer


                                                                               Waste
Figure 7-47.   Passive gas control system (venting to atmosphere) (U.S. EPA, 1993b).
                                                        T7E—Waste Gas
                                                              Inlet Vahro
                    (propanej
                         Concrete Base
                                                        Gas From
                                                        Landfill
                      Source: E.C. Jordan Co., 1990.
Figure 7-48. Example schematic diagram of a ground-based landfill gas flare (U.S. EPA, 1993b).
active gas controls into passive systems when gas pro-
duction diminishes. The conversion option and its envi-
ronmental effect (i.e., gas release causing odors, and
health and safety concerns) should be addressed in the
original design.

There are many benefits to recovering gas from surface
disposal units. Monofill gas recovery systems can re-
duce monofill gas odor and migration, can reduce the
danger of explosion and fire, and may be used as  a
source  of revenue that may help to reduce the cost of
closure. For more information on the benefits to recov-
ering monofill gas, see the references U.S. EPA (1993b)
and SWANA (1992).
7.9   Other Design Features

7.9.1  Access

At a minimum, a permanent road  should be provided
from the public road system to the site. For larger sites,
the roadway should be 20 to 24 ft (6 to 7 m) wide for
two-way traffic. For smaller operations a 15 ft (5 m) wide
road can suffice. Additionally, the  roadway should be
gravel surfaced at the least, in order to provide access
regardless  of  weather conditions.  Grades should  not
exceed equipment limitations. For loaded vehicles, most
uphill grades should be less than 7 percent and downhill
grades less them 10 percent.
                                                   150

-------
                         48* Corr. Steel Pipe
                         w/ Hinged Lid

                         Backfill, Compact by
                         Hand in 6* Layers
                              Butterfly Valve

                              Monitoring Port
            Header with 3"
            Dia. Branch Saddle

            Kanaflex PVC Hose
4" Dia Sch 80 PVC
Solid Pipe
Soil Backfill 	
                                           Bentonite/Soil Seal •
                                           Soil Backfill
                                           4" Dia Sch 80 PVC
                                           Slotted Pipe
                                           Gravel Backfill •
                                           4' Sch 80 PVC Cap
VVM*
                                                                              2--0-
                                                                               12',
                                        Slotted Length
                                           Varies
                                         (2/3 Landfill
                                           Depth)
                                 Slotted Length
                                    Varies
                                (1/2 Well Depth)
                                                                   Bore
Figure 7-49.  Example of a gas extraction well (U.S. EPA, 1993b).
Temporary roads are used to deliver sludge to the work-
ing area from the permanent road system. Temporary
roads may be constructed by compacting the natural soil
present and by controlling drainage, or by topping roads
with a layer of gravel, crushed stone, cinders, crushed
concrete, mortar, bricks, lime, cement, or asphalt bind-
ers to make the roads more serviceable.

Under the Part 505 regulation, access to surface dis-
posal sites must be restricted (see  Section 7.2.1.4).
Fencing with gates that lock might be  necessary  to
restrict access in densely populated areas. Natural bar-
riers such as hedges, trees, embankments, or ditches,
             along with warning signs might be adequate in less-
             populated areas. In remote areas, it might be sufficient
             to post warning signs that say, "Do not enter," "No tres-
             passing," or "Access restricted to authorized personnel
             only." Such posting also might be sufficient where there
             has been a low-rate application of sewage sludge.

             7.9.2   Soil Availability

             The quantity and adequacy of onsite soil for use as a
             bulking agent and  for covering sludge will have been
             determined during the site selection process. The logis-
             tics of soil excavation, stockpiling, and consumption,
                                                     151

-------
                                                         Existing Cow
                                                              • Refuse
                                 •GeotaxtHe
                                                                        Washed Gravel
            t-— PE Pipe      O
                        Bottom of Trench Excavation
Figure 7-50a.  Perimeter extraction trench system (U.S. EPA, 1993b).
                                    Flexible Hose
                                                                               Quick Connect
                                                                               Coupling
                                                                              Ortlice Plate
                          Butterfty Valve
                                                                                         Ground Surface
                                                                                     Clean So* Backfill
                        Washed Gravel

                          net
^-HOPE Pipe
Figure 7-SOb.  Perimeter extraction trench system (U.S. EPA, 1993b).
                                                           152

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                                                                        Gas
                                                                        Tieelmant/Procettlng
                                                                        FacWy
Figure 7-51.  Example of an interior gas collection/recovery system (U.S. EPA, 1993b).
however, are more thoroughly evaluated during design.
Excavation and stockpiling of soil must be closely coor-
dinated with soil use for the following reasons:
• Soil  determined to  be suitable for use and readily
  excavated may be located in selected areas of the
  site. The excavation  plan  should designate that
  these areas be excavated before filling has pro-
  ceeded atop them.
• Accelerated excavating programs may be desirable
  during warm weather to prevent the need to excavate
  frozen soil during cold  weather.
• Soil  stockpiles should  be located so that runoff will
  not be directed into future adjacent excavations and/
  or sludge filling areas and to minimize erosion.

7.9.3   Special Working Areas
Special working areas should be designated on the site
plan for inclement weather or other  contingency situ-
ations. Access roads  to these areas should be of all-
weather construction  and the area kept grubbed and
graded. Arrangements for special  working areas may
include locating such areas closer to the surface dis-
posal site entrance gate (Figure 7-52).

7.9.4   Buildings and Structures
At larger surface disposal sites or where climates are
extreme, a building should be provided for office space
and employee facilities.  Since most surface disposal
units operate year-round, regardless of weather, some
protection from the elements should be provided for the
employees.  Sanitary facilities should be provided for
both operation and hauling personnel. At a large site, a
building might be provided  for equipment storage and
maintenance. At smaller sites, buildings cannot be jus-
tified,  but trailers might be warranted.
Buildings  on sites that will be  used for less than 10
years can be temporary, mobile structures. The design
and location of all structures should consider gas move-
ment  and  differential settlement caused by decompos-
ing sludge.

7.9.5  Utilities

Large surface  disposal sites  should  have  electrical,
water, communication, and sanitary services. Remote
sites  may have to extend existing services or use ac-
ceptable substitutes. Portable chemical toilets can be
used  to avoid the high cost of  extending sewer  lines;
potable water can be trucked in; and an electric gener-
ator can be used instead of  having power lines run onto
the site.

Water should be available for drinking, dust control,
washing mud from haul vehicles before entering  the
public road, and employee sanitary facilities. A sewer
line may  be desirable, especially at large sites and
at those where leachate is collected and treated with
domestic wastewater. Telephone or radio communi-
cations may be necessary since accidents or  spills
                                                   153

-------
                          ! PAVED
                           ROAD
                                     WET WEATHER
                                      OPERATIONAL
                                      AREA
                                        TRENCH
                        DRY WEATHER OPERATIONAL
                                AREA
                                                              2—TRENCH
                                                               GRAVEL  ROAD
3*$
                                               OPERATIONS a
                                               MAINTENANCE

A
i*.ซ
u
D
^-

                                        PUBLIC   ROAD
Figure 7-52.  Special working area.
can occur that necessitate the ability to respond to calls
for assistance.

7.9.6  Lighting

If dumping operations occur at night, portable lighting
should be provided at the operating area. Alternatively,
lights may be affixed to haul vehicles and onsite equip-
ment. These lights should be situated to provide illumi-
nation to areas not covered by the regular headlights of
the vehicle.

If the site has structures (e.g., employee facilities, ad-
ministrative offices, equipment repair or storage sheds),
or if there is an access road in continuous use, perma-
nent security lighting might be desirable.

7.9.7  Wash Rack

For surface disposal units where operational procedures
call for frequent contact of equipment with the sludge, a
cleaning  program  should  be implemented.  Portable
steam cleaning units or high-pressure washers may be
used. A curbed wash pad and collection basin may be
constructed  to collect and contain contaminated wash
water. The contaminated water may be either pumped
to a septic tank/soil absorption system or dispersed with
the sludge. The washing facility should be used to clean
mud from haul vehicles, in order to keep sludge and mud
off the highway.
                         7.10  References

                          1. American Society for Testing Materials (ASTM). 1987. Annual
                            book of ASTM standards, Vol. 4.08. Soil and rock: Building
                            stones. Philadelphia, PA: ASTM.

                          2. American Society of Chemical Engineers (ASCE)/Water Pollution
                            Control Federation (WPCF). 1969, Design and construction of
                            sanitary and storm servers. In: ASCE manual on engineering
                            practice No. 37/WPCF manual of practice No. 9.

                          3. Brown and Calclwell. 1979. Colorado Springs long-range sludge
                            management study. City of Colorado Springs, CO.

                          4. Freeze and Cherry. 1979. Groundwater. Englewood  Cliffs, NJ:
                            Prentice-Hall.

                          5. Keeney, D., K. Lee, and L. Walsh. 1975. Guidelines for the ap-
                            plication of wastewater sludge to agricultural land in Wisconsin.
                            Technical Bulletin No. 88. Wisconsin Department of Natural Re-
                            sources, Madison, Wl.

                          6. Koerner, R.M.  1986. Designing with geosynthetics. Englewood
                            Cliffs, NJ: Prentice-Hall.

                          7. Lambe,  T.W., and R.V. Whitman.  1969. Soil mechanics. New
                            York, NY: John Wiley & Sons, Inc.

                          8. Loehr, R., W. Jewell, J. Novak, W. Clarkson, and G.  Friedman.
                            1979. Land application of wastes, Vol. 2. New York, NY:  Van
                            Nostrand Reinhold.

                          9. Lue-Hing, C.,  D. Zenz, and  R. Kuchenrither.  1992. Municipal
                            sewage sludge management: Processing, utilization, and  dis-
                            posal. In: Water quality management library, Vol. 4. Lancaster,
                            PA: Technomic Publishing Co.

                         10. Solid Waste Association of North  America (SWANA). 1992. A
                            compilation of landfill gas field practices and procedures (March).
                                                       154

-------
11.  Sowers, G.F. 1979. Soil mechanics and foundations: Geotechni-
    cal engineering. New York, NY: MacMillan.

12.  Sowers, G.B., and G.F. Sowers. 1970. Introductory soil mechan-
    ics and foundations, 3rd ed. New York, NY: MacMillan.

13.  Stamm, J.W., and J.J. Walsh. 1988. Pilot-scale evaluation of
    sludge landfilling: Four  years  of operation. EPA/600/2-88/027
    (NTIS PB88-208434) (May).

14.  U.S. Department of Agriculture. 1986. Urban hydrology for .small
    watersheds. Soil Conservation Service. NTIS PB87-101580 (June).

15.  U.S. Department of the Navy. 1982. Engineering design manual
    NAVFAC DM-7-1. Washington,  DC (May).

16.  U.S. EPA. 1994. A plain English guide to the EPA,503 biosolids
    rule. EPA/832/R-93/003 (June).

17.  U.S. EPA. 1993a. Use of alternative materials for daily cover at
    municipal solid waste landfills.  EPA/600/R-93/172 (NTIS PB93-
    227197)  (September).

18.  U.S. EPA. 1993b. Solid waste disposal facility criteria, technical
    manual.  EPA/530/R-93/017 (NTIS PB94-100-450). Washington,
    DC (November).

19.  U.S. EPA. 1990. Guidance for writing case-by-case permit require-
    ments for municipal sewage sludge. EPA/505/8-90-001 (May).,

20.  U.S. EPA. 1989. Seminar publication: Requirements for hazard-
    ous waste landfill design, construction, and closure.  EPA/625/4-
    89/022. Cincinnati, OH.

21.  U.S. EPA. 1988a. Guide to technical resources for the design of
    land disposal facilities. EPA/625/6-88/018. Cincinnati, OH.

22.  U.S.  EPA. 1988b. Technical resource  document: Design, con-
    struction, and evaluation of clay liners for waste management
    facilities. EPA/530/SW-86/007F. Cincinnati, OH (September).

23.  U.S.  EPA. 1988c. Lining of waste containment and other im-
    poundment facilities.  Draft technical resource document. EPA/
    600/2-88/052 (September).
24.  U.S. EPA. 1987a. Technical guidance document: Prediction/ mitigation
    of  subsidence damage to hazardous waste landfill covers. Inter-
    agency Agreement No. DW21930680-01-0. Cincinnati, OH (July).

25.,U.S.  EPA. 1987b. Implications of current soil liner permeability
    research results.  In:  Proceedings of the 13th Annual Research
    Symposium, Land Disposal Remedial  Action,  Incineration, arid
    Treatment of Hazardous Waste (July). EPA/600/9-87/015, pp. 9-25.

26.  U.S.  EPA. 1987c. Geosynthetic design guidance for hazardous
    waste landfill cells and surface impoundments. EPA/600/2-87/097
    (NTIS PB88-131263) (December).

27.  U.S.  EPA. 1986a. Highlights in U.S. technological development
    in landfiliing of sludge. EPA/600/D-86/056 (NTIS PB86-174067).
    Cincinnati, OH.

28.  U.S.  EPA. 1986b. Draft  technical resource document:  Design,
   ' construction, and evaluation of clay liners for waste management
    facilities. EPA/530/SW-86/007. Cincinnati, OH (March).

29.  U.S.  EPA. 1986c. Technical manual: Geotechnical analysis for
    review of dike stability (GARDS). EPA Contract No. 68-03-3183,
    Task 19. Cincinnati, OH (March).
30. U.S.  EPA. 1986d. Technical guidance document: Construction
    quality assurance for hazardous waste land disposal facilities.
    EPA Contract No, 68-02-3952, Task 32. Cincinnati, OH (October).

31 .U.S. EPA. 1985a. Covers for uncontrolled hazardous waste sites.
    EPA/540/2-85/002. Cincinnati, OH (September).

32. U.S. EPA. 1985b. Handbook: Remedial action at waste disposal
    sites (revised). EPA/625/6-85/006! Cincinnati, OH (October).

33. U.S.  EPA. 1984a. Hydrologic evaluation of landfill performance
    (HELP) model, Vol. 1. User's guide for Version 1. EPA/530/SW-
    84/009 (NTIS  PB85-100840).

34. U.S.  EPA. 1984b. Hydrologic evaluation of landfill performance
    (HELP) model, Vol. 2. Documentation for Version 1.   EPA/530/
    SW-84/010 (NTIS PB85-100832).

35. U.S.  EPA. 1984c. Technical-economic study of sewage sludge
    disposal on  dedicated land. EPA/600/2-84/167 (NTIS PB85-
    117216). Cincinnati, OH.

36. U.S. EPA. 1983a. Technical resource document: Lining of waste
    impoundment and disposal facility. Report No. SW-870. Cincin-
    nati, OH (March). (Revised version of Reference 19).

37. U.S.  EPA. 1981. Process design  manual for land treatment of
    municipal wastewater. EPA/625/1-89/013. Cincinnati, OH.

38. U.S. EPA. 1979. Process design manual for sludge treatment and
    disposal. EPA/625/1-79/011. Washington, D.C.

39. U.S.  EPA.  1978a.  Sludge treatment  and  disposal, Vol.  2.
    EPA/625/4-78/012. Cincinnati, OH.

40. U.S.  EPA. 1978b. Land cultivation of  industrial wastes and mu-
    nicipal wastes: State-of-the-art study, Vol. 1. EPA/600/2-78/140a
    (NTIS PB-287 080).

41. U.S. EPA. 1977. Cost of land spreading and hauling sludge from
    municipal   wastewater  treatment   plants:   Case   studies.
    EPA/530/SW/619 (NTIS PB-274-875). Washington, DC.

42. U.S.  EPA/OSW. 1987a. Draft minimum technology guidance on
    single liner systems  for landfills, surface  impoundments, and
    waste piles: Design, construction, and operation. EPA/530/SW-
    85/013. Washington, DC (May).

43. U.S.  EPA/OSW. 1987b. Draft minimum technology guidance on
    double liner systems for landfills, surface impoundments, and
    waste piles: Design, construction, and operation. EPA/530/SWr
    87/014. Washington, DC (May).

44. U.S.  Soil Conservation Service.  1972.  Drainage of agricultural
    land: A practical handbook for the planning, design, construction,
    and maintenance of agricultural  drainage systems. U.S. Depart-
    ment of Agriculture.

45. Van Schilfgaarde, ed.  1974. Drainage for agriculture. Madison,
    Wl: American Society of Agronomy.

46. Wahls, H.E. 1981. Tolerable settlement of buildings. J. Geotech.
    Eng. 107(GT11):1,489-1,504.

47. Winterkom, H.F., and H.Y. Fang. 1975. Foundation engineering
    handbook. New York, NY: Van Nostrand Reinhold.
                                                             155

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                                             Chapter 8
                           Surface Disposal 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  (household,  non-commercial,  non-industrial
sewage) (see Section 3.2.2). Table 3-2 in  Chapter 3 lists
some characteristic of septage.

The most  common, and  usually  most economical,
method of domestic septage disposal is land application
(e.g., land spreading, irrigation, overland flow) which is
not addressed in this manual. Disposal  at an existing
wastewater treatment plant is a viable and economical
option if the plant is reasonably close to the source and
has adequate  processes and capacity  to handle the
domestic septage.

Surface disposal practices for domestic septage include
placement  in monofills (trenches), lagoons, and munici-
pal solid waste landfills.

8.1   Regulatory Requirements for
       Surface Disposal  of  Domestic
       Septage

The regulatory requirements for the surface disposal of
domestic septage  are not as extensive as those  for
sewage  sludge. Neither the pollutant  limits  nor the
pathogen requirements of Part  503 apply if domestic
septage is  placed on an active sewage sludge unit. The
regulation does, however, specify requirements for vec-
tor attraction reduction for domestic septage that is sur-
face disposed.

Two alternatives are available for placing domestic sep-
tage on an active sewage sludge unit (see Options 9-12,
Table 3-9 in Chapter 3). One alternative is to achieve
vector attraction reduction by raising the pH of the do-
 mestic septage to 12 with alkali addition for 30 minutes,
 and maintaining the pH at 12 or greater for 30 minutes
without adding more alkali. If pH  reduction is used to
 achieve vector attraction reduction, each container of
 domestic septage must be monitored for compliance. The
 person who placed the domestic septage on the active
 sewage sludge unit must then certify that vector attrac-
 tion reduction was achieved (see Figure 8-1) and  de-
velop a .description of how it was achieved. The certifi-
cation and the description must be kept for 5 years.

If vector attraction reduction  is not achieved by alkali
addition (as described above), the owner or operator of
the surface disposal site must achieve vector attraction
reduction by injecting or incorporating the domestic sep-
tage into the soil, or by covering it with soil daily. Certi-
fication that all these requirements have been  met and
a description of how they were met must be developed
and maintained for 5 years. (Figure 8-1 shows the  re-
quired  certification statement.)

If domestic septage is placed in a monofill (such as a
trench), surface impoundment, dedicated disposal site
or other sludge-only surface disposal site, its disposal is
covered by the requirements in the Part 503 regulation
for such disposal sites (except for requirements for pol-
lutant limits and pathogen reduction). These requirements
are discussed further in Chapters 3, 4, 5, 7, 9, and 10.

If domestic septage is placed in a municipal solid waste
landfill, its disposal is covered by the requirements of
40 CFFt  Part 258 for the disposal of non-hazardous
waste. These requirements  are discussed in  Section
3.4.3. Note that because of the requirement that waste
pass the Paint Filter Liquids Test (see Section 3.4.3),
domestic septage must be dewatered so that it contains
no free liquid  before it can be placed in a municipal solid
waste  landfill.

Compliance with federal regulations governing domestic
septage does not ensure compliance with state require-
ments. State programs may not define domestic septage
the same way as the federal regulations. In addition,
state requirements may be more restrictive or may be
administered in a different manner from the federal regu-
lation.  It is important to check with the state  septage
coordinator to find out about state requirements.

8.2   Domestic Septage Disposal Lagoons

The use of lagoons for septage disposal is a common
alternative in rural areas. As discussed in Section 7.5.3,
if the lagoon is not part of the treatment process then
these  lagoons are considered surface disposal sites
 under the Part 503 rule.
                                                  157

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                            An individual placing domestic septage on a surface disposal site must maintain
                            the following certification statement for 5 years:
                                "I certify, under penalty of law, that the vector attraction reduction
                                requirements in ง503.33(b)(12) 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 vector attraction
                                requirements have been met I am aware that there are significant penalties
                                for false certification, including the possibility of fine and imprisonment."
                            The owner or operator of the surface disposal site must maintain the following
                            certification statement for 5 years:
                                "I certify, under penalty of law, that the management practices in ง503.24
                                and the vector attraction reduction requirements in [insert ง303.33(b)(9)
                                through ง503.33(b){l 1) when one of those requirements is met] havertiave
                                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 management practices [and the vector attraction requirements, if
                                appropriate] have been met I am aware that there are significant penalties
                                for false certification, including the possibility of fine and imprisonment."
                                Signature
                 Date
 Flgur* 8-1.  Certifications required when domestic septage Is placed In a surface disposal site (U.S. EPA, 1994).
 Domestic septage disposal lagoons are usually a maxi-
 mum of 1.8 m (6 ft) deep and allow no effluent or soil
 infiltration. These lagoons require placement of domes-
 tic septage in small incremental lifts (15 to 30 cm, or 6
 to 12 in.) and sequential loading of multiple lagoons for
 optimum drying. Most are  operated  in  the unheated
 anaerobic or facultative stage. Odor problems may be
 reduced  by placing the lagoon inlet pipe  below liquid
 level and having water available for haulers to immedi-
 ately wash any spills into the lagoon inlet line (U.S. EPA,
 1994). Section 7.5.3 presents detailed information about
 lagoon design.

 8.3   Monofills (Trenches) for Domestic
       Septage Disposal

 Domestic septage is placed sequentially in multiple
trenches in small  lifts,  15 to  20 cm  (6 to  8 in.), to
minimize drying  time. When  the trench  is filled with
domestic septage,  0.6 m  (2 ft)  of  soil should  be
placed as a final covering, and new trenches opened.
An alternate  management  technique  allows  a filled
trench to remain uncovered to permit as many solids to
settle, as well as liquids to evaporate and leach out, as
possible. Then the solids, as well as some bottom and
sidewall material, are removed and the trench is reused
(U.S. EPA, 1984).

Additional information on monofills is presented in Sec-
tion 7.5.2.


8.4   Codisposal at Municipal Solid Waste
       Landfill Unit

Design information for codisposal at a municipal solid
waste landfill  is presented in Section 7.6; codisposal
operation is discussed in Section 9.3.3.
                                          "i
8.5   References

1.  U.S. EPA.  1994. A plain English guide to the EPA 503 biosolids
   rule. EPA/832/R-93/003.

2.  U.S. EPA. 1984. Handbook:  Septage treatment  and  disposal.
   EPA/625/6-84/009. Cincinnati, OH (October).
                                                       158

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                                             Chapter 9
                                             Operation
9.1   Purpose and Scope
The purpose of this chapter is to introduce an approach
for implementing a sewage sludge disposal operation.
The  operation of a sewage sludge surface  disposal
site can be viewed as an ongoing construction project.
As with  any construction project, it must  proceed
according to detailed plans. Unlike conventional con-
struction, however, the operating parameters of a sew-
age sludge surface disposal site often change and may
require innovative alterations and contingency plans. An
effective operation requires a detailed operational plan
and a choice of equipment compatible with the sludge
characteristics, the  site  conditions,  and the  selected
active sewage sludge unit.

9.2   Regulations

9.2.1   Part 503

9.2.1.1   Management Practices That Affect the
         Operation of Surface Disposal Sites
The Part 503 rule includes management practices that
affect the daily operation of  surface  disposal  sites.
These management practices  must be followed  when
sewage  sludge is placed on  a surface disposal site
because they help protect human health and the envi-
ronment from the  reasonably  anticipated adverse ef-
fects of pollutants in sewage sludge (U.S. EPA, 1994).
The following management practices are addressed in
Chapter 7:
• Collection of Runoff (Section 7.2.1.1 and Section 7.8.2).
• Collection  of Leachate (Section 7.2.1.2 and Section
  7.5.7).
• Limitations on Methane Gas  Concentrations (Section
  7.2.1.3 and Section 7.8.3).
• Restrictions of Public Access  (Section 7.2.1.4 and
  Section 7.9.1).
• Protection  of Ground Water  (Section 7.2.1.5).
The following management practices  required  under
Part 503 also impact the operation of a surface disposal
site (U.S. EPA, 1994):
• Restrictions on Crop Production. Food, feed, or fiber
  crops may not be grown on an active sewage sludge
  unit unless  approved by the permitting authority. The
  owner or operator of the surface disposal site must
  demonstrate to the permitting authority through man-
  agement practices that public health and the environ-
  ment are  protected if  crops  are grown.  If the
  owner/operator wishes to grow crops on the site, he
  or she must  obtain  permission from  the regulatory,
  agency. If permission is  granted the owner/operator
  will be required to implement  certain management
  practices to ensure  that unsafe levels of pollutants
  are not taken up by crops that are eaten by people.
  These special management practices might include
  testing crops for the presence of pollutants and test-
  ing animal  tissue for the  presence of pollutants if
  animal feed  is  produced on the site,  or setting a
  monitoring  schedule for the crops  and any animal
  feed products derived from  the site.

• Restrictions on Grazing. Animals must not be allowed
  to graze on  an  active sewage sludge unit unless
  approved by  the permitting  authority. The owner/op-
  erator of a surface disposal  site must demonstrate to
  the permitting authority  that public health  and the
  environment are protected if animals  are allowed to
  graze. If the owner/operator wishes to graze animals
  on the  site,  he or she  must obtain  a permit. The
  permit would require  specified management prac-
  tices, such  as monitoring the concentration of pollut-
  ants  in any  animal product  (dairy or meat). This
  restriction on grazing helps ensure that unsafe levels
  of pollutants  do not find their way into animals from
  which people obtain food.

A site on which the production of crops and/or grazing
is allowed is considered a dedicated beneficial  use site.
(Operational considerations at beneficial TINE sites are
discussed in Section 9.3.4.3 of this chapter.)

9.2.1.2  Operational Standards for Pathogen and
         Vector Attraction Reduction

Pathogens are disease-causing organisms,  such  as
certain bacteria and viruses,  that might be present in
sewage sludge. Vectors are animals, such as rats,'or
                                                  159

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 insects, such as flies, that might be attracted to sewage
 sludge and can spread disease after coming into contact
 with sewage sludge. The Part 503 rule includes require-
 ments concerning the control of pathogens and the re-
 duction of vector attraction for sewage sludge placed
 on an active sewage sludge unit site. Sewage sludge
 can be placed in an active sewage sludge unit only if
 the pathogen and vector attraction reduction require-
 ments are met (see Section 3.4.2.2, Section 3.4.2.3,
 and Table 3-9).

 To meet pathogen and vector attraction reduction re-
 quirements under Part 503 the following daily operation
 should take place (U.S.  EPA, 1994):

 • For pathogen reduction,  either the  sewage  sludge
   placed  on an active sewage sludge unit must meet
   Class A or Class B pathogen requirements, or a cover
   (soil or other material) must be placed on the active
   sewage sludge unit at the end of each day. If a daily
   cover is placed on the active sewage sludge unit, no
   other pathogen reduction requirements  apply (see
   Section 3.4.2.2).

 • For vector attraction reduction, one of several options
   listed in Table 3-4 must be met. These include placing
   a daily  cover on the active sewage sludge unit, or,
   injecting or incorporating the  sewage sludge into the
   soil (see Section 3.4.2.3).

 In most cases, owners or operators of surface disposal
 sites will place a daily cover on the active sewage sludge
 unit to meet pathogen and  vector attraction reduction
 requirements (U.S. EPA, 1994).

 Regarding vector attraction  reduction,  if the method
 used  to place sewage sludge at a TINE site is subsur-
 face injection or incorporation (see Section 7.7.4), then
 the site can meet the Part 503 requirement for vector
 attraction  reduction  (Options 9 or 10) if the sewage
 sludge is injected or incorporated within a specified time
 frame after the sewage sludge has undergone a patho-
 gen reduction process, as described in Section 3.4.2.2
 and Section 3.4.2.3. If a method other than subsurface
 injection or incorporation is used, then the other options
 of achieving vector attraction  reduction  described in
 Section 3.4.2.3 must be used (see Section 9,3.4.3).

 9.2.1.3  Other Requirements Under Part 503
        Affecting Operation

The following requirements under part 503 also impact
daily operations at sewage sludge surface disposal sites
but have been addressed elsewhere in this document:

• Frequency of monitoring requirements (see Section 10.2)

• Reporting requirements (see Section 11.2)

• Recordkeeping requirements (see Section 11.2)
 9.3   Method-Specific Operational
       Procedures

 For the purposes of this chapter, the site operation
 may be viewed in two parts: the first part (Section 9.3)
 concerns operational procedures that are specific to
 the chosen active sewage sludge unit; the second part
 (Section  9.4) concerns general operational  proce-
 dures that are independent  of the  active sewage
 sludge unit.

 9.3.1  Operational Procedures for
        Monofilling

 Operations dependent on the type of monofill include:

 • Site preparation

 • Sludge unloading

 • Sludge handling and  covering

 Because these operations vary for each monofill, they
 will be discussed as functions of the  monofills intro-
 duced in Chapter 2.

 9.3.1.1  Trench

 For trenches, subsurface excavation is required so
 that sludge can be  placed entirely below the original
 ground surface. In trench applications, the sludge is
 usually dumped directly into the trench from haul ve-
 hicles. Soil is not used as a sludge bulking agent. Soil
 is used as cover, usually in a single, final application.

 Two kinds of trenches have been identified including
 (1) narrow trench and (2) wide trench. Narrow trenches
 have widths  less than 10 ft (3.0 m).  Wide trenches
 have widths greater than 10 ft (3.0 m). Section 2.3.1
 and Section 7.5.2.1  should be consulted for specific
 design criteria.

 Site Preparation

 Site preparation includes all tasks required prior to the
 receipt of sludge. Tasks include clearing  and grub-
 bing, grading the site, constructing access roads, and
 excavating trenches.

 The location of access roads depends on the topog-
 raphy and the land utilization  rate. Narrow trenches
 use land  rapidly and require more  extensive road
 construction. Wider and/or longer trenches may require
 vehicle access roads along both  sides of the trench.

 Prior  to  grading, the area  should  be cleared and
 grubbed. Grading should be done on the site  (1) to
control runoff and (2) to provide grades compatible
with equipment to be used.  For  example, drag lines
and trenching machines operate more efficiently on
level  surfaces. Narrow  trenches may require less
grading due to their applicability to hilly terrain.
                                                 160

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Progressive trench construction is  the  most efficient
procedure for a narrow trench  operation. The  initial
trench is constructed using appropriate equipment and
the soil either (1) piled along the length of the trench, or
(2) stockpiled  in a designated area, or (3) graded to
ground level. Soil is often piled on the uphill,side of the
trench and  used to  prevent  runoff from entering  the
trench. Succeeding trenches are constructed parallel to
the initial trench. The trench  dimensions and the dis-
tance between the trenches should follow design speci-
fications.
Trenches may require  dikes positioned intermittently
across  the  width  of the  trench, especially  if  such
trenches are long. The dikes should be  of sufficient
height to contain the sludge and attendant liquids and
allow proper trench filling and  covering. Equipment may
be used inside wide trenches to construct dikes.
On-going site preparation is critical for proper execution
of a trenching operation. Depending on  the quantity of
sludge  received, a designated trench'volume should
always  be  maintained in advance of filling operations.
Ideally, trenches should be prepared at least one wdek
ahead of the current landfilling operation.

Sludge Unloading
.Signs should be placed to designate which trench is the
active sewage sludge unit. Sludge is usually unloaded
from haul vehicles via direct dumping. Metal extension
chutes or pumping, however,  may also be employed.  If
direct dumping is employed, an appropriately sized area
should  be prepared  at the  lip of the  trench so that
transport vehicles can safely back up to the trench edge
for unloading. Sludge unloading  can occur along the
length of both sides of the trench if necessary. The entire
unloading  area should be kept clear  of discharged
sludge  and periodically regraded to facilitate safe un-
loading operations.

Sludge Handling and Covering
Sludge should be uniformly distributed  throughout the
trench.  Otherwise,   depressions that could   cause
ponding are likely to occur as the fill settles. Narrow and
wide trenches should be filled only to a level where a
sludge  overflow will not occur due to displacement dur-
ing cover application. Markers on trench sidewalls can
be used for  this  purpose. The  appropriate level for
sludge  filling can best be established via experimenta-
tion using test loads.
Concurrent excavation, filling, and covering of trenches
is a sequential operation that requires a coordination  of
effort. When  the  sludge has filled  the trench  to the
designated level, cover material should be applied using
either soil freshly excavated from a parallel trench or soil
stockpiled during  excavation of the trench being filled.
 Depending upon the solids content of the sludge and the
width of the trench, coyer application should proceed as
follows:

If the sludge has a solids content from 15 to 20 percent,
the width of the trench should be 2 or 3 ft (0.6 to 0.9 m).
Cover  application should be via equipment based on
solid ground adjacent to the trench. Covering equipment
may include a backhoe with loader, excavator, or trench-
ing machine.

If the sludge has a solids content from 20 to 28 percent,
the width of the trench is technically unlimited. It is
limited, however, by the requirement that cover be ap-
plied by equipment based on solid  ground. Covering
equipment may include a backhoe with loader, excava-
tor, track loader, or dragline.

If the sludge has a solids content of 28 percent or above,
the width of the trench is unlimited.  Cover application
can  be via equipment which proceeds  out over the
trench pushing cover over the sludge. Covering equip-
ment usually is a track dozer. In all cases, initial layers
of cover should be carefully applied to minimize sludge
displacement. (See Chapter 12 for information on final
cover requirements for sewage sludge monofills.)

Operational Schematics

The preceding information has been  included to gener-
ally  describe the  operation  of trenches. Figures 9-1
through 9-4 illustrate specific trench operations,

9.3.1.2  Area Fill

For area fills, sludge is usually placed above the original
ground surface. In  area fill applications, soil is  usually
mixed with the sludge as a bulking agent. Cover may be
used in both intermediate and final applications.

Three kinds of area fills have been defined including (1)
area fill mound, (2) area fill layer, and (3) diked contain-
ment.  In area fill mound operations, sludge/soil mixtures
are usually stacked into piles approximately 6 ft (1.8 m)
high. In area fill layer operations,  sludge/soil mixtures
are  spread  evenly  in layers 0.5 to 3 ft (0.15 to 0.9 m)
thick.  In diked containment operations, sludge (with or
without bulking soil) is dumped into pits contained by
dikes  constructed above the ground surface. Section
2.3.2 and Section 7.5.2.2 should be consulted for spe-
cific design criteria.

Area Fill Mounds

Area fill mounds may be employed in a variety of topog-
 raphies. Usually such operations are conducted on level
ground. Mound monofills, however, are also well suited
to construction against a hillside that can provide con-
tainment on one or more sides.

 Site Preparation. The first step is to prepare the sub-
 grade. Depending on design  specifications this  may
                                                   161

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 Figure 9-1.  Narrow trench operation.

                                sv    s-S'  SsZ
                              &  *>'  *V-
                  j'T-Z^^f+WBg^tKfJfl _^^f J\f^^^//\    f^lr      ff •
                - •-'y^^*ulLClA^j^->'^ .Xx^/f \  >  x-^    ^
                >-^/(M4>:'      >"
                                   -•x*'
Figure 9-2. Wide trench operation at solid waste landfill.
Figure 9-3. Wide trench operation with dragline.
                                   162

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Figure 9-4.  Wide trench operation with interior dikes.

include underdrains and/or liners for leachate collection.
Due to  the  large amount of soil required for  proper
operation  of area fill  mounds, emphasis should be
placed on securing sufficient soil material. Accordingly,
the fill should be confined to a small area and proceed
vertically to the maximum extent possible. This  will re-
duce the areal extent of the monofill and consequently
reduce erosion and silt-laden runoff from denuded ar-
eas, provided the slope does not become excessive.

The excavation can be carried out in  phases to take
advantage of soil differences. Any soil that has to be
stockpiled for use as a sludge bulking agent should be,
placed in compacted, sloping piles. To keep the soil dry,
piles may be covered with tarpaulins. Wet soils, because
they are not suitable for sludge bulking, should not be
stockpiled. Soil that is stockpiled should be placed as
close as possible to points of eventual use and  access
to stockpiles provided.
Sludge Unloading. The sludge may be unloaded either
in the filling area or in the designated  unloading and
mixing area near the  bulking agent stockpile. The un-
loading area should be clean and relatively level for safe
passage of trucks. Haul vehicles should not drive over
completed sludge filling areas.

Sludge Handling and Covering. Operational procedures
should be provided to specify what soils are to be mixed
with sludge, where they are  to be obtained,  and how
they are to be mixed and/or placed over the sludge. The
amount of material required for each function is deter-
mined by site design  specifications  that take into ac-
count soil and sludge characteristics. Preliminary trial
and error tests to determine sludge/soil ratios that pro-
duce sludge with appropriate consistencies should be
attempted during initial operations.

Construction  of area fill mounds requires  that  the
sludge/soil mixture  be   relatively stable. Sludge/soil
mounds  are generally applied in a series of lifts with
each lift  containing one level of mounds. When com-
pleted, the lift should be covered with a layer of  soil
sufficient to safely support on-site operating equipment.
(See Chapter 12 for information on final cover require-
ments for sewage sludge monofills.),

Area Fill Layer

Area fill layers may also be employed in a variety of topog-
raphies.  Layer operations consist of a series of sludge
layers with intermediate and final cover applications.

Site Preparation. As with area fill mounds, the first step
is to prepare the subgrade. Again, liners and/or subdrain
systems may be utilized depending on hydrogeological
conditions. Fill areas for layer  operations should be
nearly level.  Although the soil  requirements of such
operations are less than those of area fill mounds, it may
be necessary to import soil. In any case, soil stockpiles
should be established, both for use  as bulking agents
and cover soils. Areas should be excavated only as they
are used, to the maximum extent possible. This will
reduce the amount of denuded area subject to erosion.
                                                   163

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 Sludge Unloading. Specific unloading and sludge/soil
 mixing areas  may be maintained or sludge can be
 placed directly in the fill area. An effective method in
 layer operations  is to maintain soil stockpiles on the fill
 area itself. Bulldozers then mix and layer the sludge in
 one operation. Again, storage areas should be located
 away from traffic.

 Sludge Handling and Covering. In general,  design
 specifications based on sludge characteristics will give
 some indication  of  the  required amounts of bulking
 agent.  Nevertheless, it is always advisable to conduct
 preliminary trial  and error tests  to determine bulking"
 ratios appropriate for supporting equipment. The depth
 of intermediate and final cover can also be determined
 in this manner. (See Chapter 12 for information on final
 cover requirements for sewage sludge monofills.)

 Diked Containment

 Diked containments are essentially aboveground wide
 trenches and,  as such, use  similar procedures  and
 equipment. The design and construction of dikes is more
 complex. Diked  containments are  generally  used at
 sites with high ground-water tables or bedrock, and/or
 where a sewage sludge with a  low  solids content is
 being disposed.

 Site Preparation.  The first step in preparing the site for
 diked containment is to provide a suitable subgrade or
 a liner,  if necessary.  (See Chapter 7 for information on
 foundations, liner and leachate collection systems, and,
 slope stability analyses.) The dike  base is then con-
 structed maintaining  design dimensions and slopes
 (generally from 2H:1V to  3H:1V for sideslopes).  Suc-
 ceeding layers are then applied and  each layer com-
 pacted by passing equipment over it.  Alternatively, the
 containment area may be constructed against one or
 more steep sideslopes. A ramp should be provided for
 unloading vehicles. *

 Sludge Unloading. Sludge may be unloaded from the
 top of the dike  or in an area designated for sludge/soil
 mixing. Slopes and grades of access  roads should be
 maintained to design specifications. Provisions should be
 made for inclement weather (e.g., stockpiled soil kept dry).

 Sludge Handling  and Covering. The containment area
 is filled with sludge in layers, usually with intermediate
 soil or gravel cover provided at predetermined heights.
 Draglines are frequently used to apply  intermediate and
 final cover. (See  Chapter 12  for information on  final
 cover requirements for sewage sludge monofills.)

 Operational Schematics

The preceding information has been included to gener-
ally describe the  operation  of area fills. Figures  9-5
through 9-8 illustrate specific area fill operations.
 9.3.2  Operational Procedures for Lagoons

 Facultative sludge lagoons and sludge drying lagoons
 are used for surface disposal of sewage sludge.1 Sec-
 tion 2.5 and Section 7.5.3 should be consulted for spe-
 cific design criteria for these active sewage sludge units.

 9.3.2.1   Facultative Sludge Lagoons

 Operational considerations for facultative sludge la-
 goons include the loading  or placement of sludge into
 the FSLs and routine operation.

 Start-up and Loading

 FSLs should be initially filled with effluent. Ideally, that
 effluent should then have about three to six weeks for
 development  of an  aerobic surface layer prior to the
 introduction of digested sludge. All FSLs should be
 loaded daily,  with the loading distributed equally be-
 tween FSLs. Loadings should be held below 20 pounds
 VS per 1,000 square feet per day (1.01 VS/ha-d) on an
 average annual basis. As indicated earlier, considerable
 flexibility does exist. Loads can vary from day to day,
 and batch or intermittent loading of once every four days
 or  less is acceptable. Shock loadings, such  as with
 digester cleanings, should be distributed to all operating
 FSLs in proportion to the quantity of sludge they pos-
 sess. FSLs should be loaded during periods of favorable
 atmospheric conditions, particularly just above ground
 surface, to maximize odor dispersion. The fixed and
 volatile sludge solids loadings to the FSLs and their
 volatile contents should be  monitored quarterly.

 Daily Routine

 Surface mixers should operate for a period of between
 6 and 12 hours. Operation should not coincide with FSL
 loading and should always  be during the hours of mini-
 mum human exposure (usually midnight to 5 a.m.) and
 during periods of favorable atmospheric conditions. FSL
 supernatant return to the wastewater treatment process
 should be regulated to minimize shock loadings of high
 ammonia. Supernatant return flows should be monitored
 so that their potential impact on the liquid treatment
 process can be discerned. The  sludge blanket in  a
 lagoon should not be allowed to rise higher than 2 feet
 below the  operating water surface.

 9.3.2.2  Operations for Sludge Drying Lagoons

 Operating  procedures for drying lagoons used for final
 disposal include:

 • Pumping  liquid  sludge,  over a  period  of several
  months or more, into the lagoon. The pumped sludge
 As discussed in Sections 2.5 and 7.5.3, the surface disposal provi-
sions of the Part 503 rule do not apply when sludge is treated in a
lagoon. Section 1.1 provides more information on differentiation be-
tween sludge disposal, storage and treatment.
                                                  164

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Figure 9-5.  Area fill mound operation.
 Figure 9-6.  Area fill layer operation.
  Figure 9-7.  Area fill operation inside.trench.
                                                              165

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                    SOIL STOCKPILE
                                                                                       SOU. STOCKPILE
 Figure 9-8. Diked containment operation.

   is normally stabilized prior to application. The sludge
   is usually applied  until a lagoon depth of 24 to 48
   inches (0.7 to 1.4 m) is achieved.

 • Decanting supernatant, either continuously or inter-
   mittently, from the lagoon surface and returning  it to
   the wastewater treatment plant.

 • Filling the lagoon to a desired sludge depth and then
   permitting it to  dewater. Depending on the climate
   and the depth of applied sludge, a solids content of
   between 20 to 40 percent will be obtained in 3 to 12
   months.

 9.3.3  Operational Procedures for Codisposal

 In codisposal operations, sludge is disposed of at an
 MSW landfill. Two kinds of codisposal operations have
 been identified including (1) sludge/solid waste mixture
 and (2) sludge/soil mixture. For sludge/solid waste mix-
 tures, sludge is mixed directly  with solid  waste and
 landfilled at the working face. For sludge/soil mixtures,
 sludge is mixed with soil and used as cover over com-
 pleted refuse  fill areas. Section 2.7 and Section 7.6
 should be consulted for specific design criteria.

 9.3.3.1   Sludge/Solid Waste Mixture

 At the landfill, once sludge  receipt has begun, every
 effort should be made to take full advantage of the
 absorptive  capacity of the solid waste. Consequently,
the sludge should be mixed with the solid waste  as
thoroughly  as possible. One procedure employed calls
for solid waste to be  dumped at the bottom of the
working face, and  subsequently  pushed, spread, and
compacted by equipment working up the working face.
 Under these circumstances, sludge can be handled in
 two alternative ways. The first way includes:

 1. Dump the solid waste at the bottom of the working face.

 2. Dump the sludge atop the solid waste pile.

 3. Thoroughly mix the sludge and solid waste.

 4.  Push, spread, and compact the sludge/solid waste
    mixture up the working face.

 The second method can be accomplished in the fol-
 lowing way:

 1.  Dump the solid waste at the bottom of the working face.

 2.  Push, spread, and compact the solid waste up  the
    working face.

 3.  Dump the sludge at the top of the working  face.

 4.  Push the  sludge down the working face, spreading
    it evenly across  the solid waste.

 If small quantities of sludge are received at MSW land-
 fills (i.e., less than  5 percent) it may be desirable to
 confine sludge dumping to a selected location on the
 working face. This approach is useful in MSW land-
 fills that  are sufficiently  large to ensure  that  solid
 waste dumping proceeds simultaneously along a wide
 working face.

 Precautions should  be taken to contain any sludge that
 escapes from the working  face. Containment can  be
 achieved either by (1) landfilling the sludge  in a small
 depression or (2) constructing a refuse or soil  berm at
the bottom of the working face.

Another factor to be  considered at MSW landfills receiv-
ing  sewage sludge  is the increased potential  for  odor
                                                  166

-------
problems to occur. Appropriate steps can be taken to
control odors  including  more frequent application of
cover and spot addition of lime.

9.3.3.2   Sludge/Soil Mixture

Another option for handling sludge at MSW landfills is
mixing the sludge with soil and then applying the mixture
as cover material oversolid waste filled areas. Although
this technically is  not sludge landfilling, it is  a viable
alternative, is particularly useful in promoting vegetative
growth in completed fill areas, and is performed at nu-
merous MSW landfills.
If a sludge/soil mixture is determined to be a suitable
material for the erosion layer of the final  cover, the
mixture can be applied as follows:

1. Spread sludge as received uniformly over the ground
   surface in a 3 to 6 in. (8 to 15 cm) thickness  in an
   area designated for this  purpose.
2. Disc the sludge into the soil. The resulting mixture of
   sludge to soil should be about 1:1.
3. If  necessary, spread lime or a masking  agent over
   the sludge/soil  mixture for odor control.

4. After a period ranging from 1 to 8 weeks (depending
   on rainfall and  climate)  scrape up the  sludge/soil
   mixture and spread it over the clay infiltration layer

9.3.3.3  Operational Schematics
The preceding information has been included to gener-
ally describe the operation of MSW landfills.  Figures 9-9
through 9-11 illustrate specific codisposal operations.

 9.3.4  Operational Procedures at Dedicated
        Surface Disposal Sites

 Important  operational considerations at DSD sites in-
 clude aesthetics  (i.e., community concerns),  labor,
 and issues related specifically to beneficial DSD sites.
 Each of these operational considerations for DSD sites
 are discussed below. Design considerations affecting
 operations at DSD sites, such as determining the most
 appropriate sludge placement method to use and cal-
 culating the acceptable sludge disposal rate, are ad-
 dressed in Section 7.7.

 9.3.4.1   Aesthetics at DSD Sites
 The  major community concern at most DSD sites is
 odor. If the DSD site is located on a treatment plant site
 that  is remote from public areas, odor may not present
 a problem. But DSD sites  may need to be located in
 populated areas if that is where land is available, espe-
 cially in urban areas.

 Generally, odor problems from sludge are the result of
 anaerobic (septic) conditions. When disposing large
quantities of liquid sludge at DSD sites, the soil should
be maintained in an aerated condition via surface drain-
age that precludes ponding of water on the site's surface
and includes subsurface drainage and/or tillage (if nec-
essary). Subsurface injection by sludge spreading vehi-
cles provides another means of reducing odors.

Liquid sludge storage lagoons at DSD sites are a po-
tential  source of odor.  Use of a lagoon, if properly
designed, will reduce the potential for odors. If the
sludge, is well stabilized, odor problems are  usually
infrequent but may occur (e.g., during a spring  thaw
after extended cold weather or during a major distur-
bance of the sludge lagoon  as  would occur during
bottom sediment cleanout). Typical attempts at control-
ling odors from sludge lagoons involve:

• Locating the .sludge lagoon as far from public access
  areas as  possible.

• Providing as large a buffer  area around the site as
  possible.

• Adding lime to the lagoon.

•  If the POTW sludge  treatment process is having
  problems (e.g., a sour digester),  if  possible the re-
  sulting poorly stabilized sludge  should not be added
  to the DSD site storage lagoon.

Dust and noise levels from use  of heavy equipment
(e.g., tractors, subsurface injector  vehicles) at DSD
sites may be a concern in some communities.  In an
agricultural  area, dust and noise should be no worse
than expected from normal   farming operations and
should create no problems. In an urban area, use of
buffer zones and vegetative screening (trees arid
shrubs around the site) may be necessary to  mitigate
 public impact.
 9.3.4.2   Labor

 Labor needs for DSD sites can vary widely, 'from one
 hour of operator time weekly for smaller sites using
 spray methods to 11  persons  needed for one-half year
 each (where climate  limits sludge spreading to certain
 seasons) at sites with larger operations using the sub-
 surface injection method, based on reports from individ-
 ual DSD sites.  The 11-person operation included one
 person for each dredger, one person for each injector,
 and one person for each tiller tractor. Two people were
 hired  as relief  personnel  for the injector and tractor
 operators, and one person served as supervisor of the
 crew  (U.S  EPA, 1984). Additional  personnel  will  be
 heeded at  dedicated beneficial use sites where crops
 are grown (e.g., for seeding and harvesting).
                                                   167

-------
                  /^SEHS
                  foad/uK
                 j^fes^Sp*
 Figure 9-9.  Sludge/solid waste mixture operation.
Figure 9-10.  Sludge/solid waste mixture with dikes.
Figure 9-11. Sludge/soil mixture.
                                                 168

-------
9.3.4.3   Operational Considerations at Dedicated
         Beneficial Use Sites
A  POTW or other DSD site owner might choose to
establish a beneficial DSD site if soil erosion or soil
acidity are a problem at the site or if the facility is
committed to a beneficial use policy. The sewage sludge
increases the  soil's  productivity  and can reduce soil
erosion and acidity. The high disposal rates of sewage
sludge placed on these sites can help supply nutrients
that act as fertilizers, as well as organic matter that
conditions the  soil.  Crops grown on beneficial  DSD
sites have been sold as animal feed or for use in the
production of methanol or other alternative fuels (Lue-
Hing, 1992).
Part 503 requires that an owner/operator of a beneficial
DSD site must be able to demonstrate to the permitting
authority  that,  by  implementing  certain  management
practices, public health and the environment will be
protected if crops are grown or animals are grazed. The
permitting authority may specify  site-specific manage-
ment practices to ensure that unsafe levels of pollutants
are not taken up by crops that might be eaten by people
(including animals that are allowed to graze on the site).
Such  management  practices may  include testing of
crops or animal tissue (e.g., dairy or meat) for the pres-
ence of pollutants and specification of a monitoring
schedule for the testing.
The crops chosen to be grown at a beneficial DSD site
need to be compatible with the  site's sludge disposal
 rate and the sludge disposal method  used at the site
 (see Sections 7.7.4 and 7.7.5). Crops with high nutrient
 needs  (e.g.,  nitrogen) will be able to tolerate higher
 sludge disposal rates and  also can help reduce  the
 amounts of nutrients that may be released as pollutants
 into surface runoff and leachate.

 9.4  General Operational Procedures

 9.4.1   Management Practices Required Under
        Part 503
 Surface disposal site owners/operators must meet the
 Part 503 management practice for surface disposal re-
 lated  to operation of the  surface disposal site. These
 address the operation of leachate collection systems,
 collection of surface water runoff, crop production and/
 or grazing of animals, access restrictions, and include
 monitoring requirements and pathogen and vector con-
 trol requirements.

 9.4.1.1  Leachate Collection System
 If the surface disposal site owner chooses to have a liner
 and leachate collection system onsite (in lieu of meeting
 the Part 503 pollutant limits for surface disposal), then
 Part 503 requires that site owners operate the leachate
collection system according to design specifications and
must perform routine and other needed maintenance for
the system. Chapter 7 includes a more detailed discus-
sion  of  leachate collection at sewage sludge surface
disposal sites.


9.4.1.2   Collection of Surface Water Runoff

A surface disposal site owner/operator must implement
the management practices required for all surface dis-
posal sites. One of the management practices requires
that  surface water runoff be collected from an active
sewage sludge unit and that the runoff collection system
must be capable of handling  runoff from a 24-hour,
25-year storm event. Chapter 7 includes a more detailed
discussion of collection of runoff at sewage sludge sur-
face disposal sites.


9.4.1.3   Crop Production and/or Grazing of
         Animals

Part 503 management practices state that no crop pro-
duction or grazing can be conducted at any surface
disposal site, including beneficial DSD sites, unless the
owner/operator  can  demonstrate to the permitting
authority that, through management practices,  public
health and the environment  will be protected from any
reasonably anticipated adverse effects of pollutants—in-
cluding pathogens—in sewage sludge when crops are
grown or animals are grazed.


9.4.1.4  Access Restrictions

 Under Part 503, public access to a surface disposal site
 must be restricted while an active sewage sludge unit is
on the site and then for 3  years after the last active
 sewage sludge unit has been closed. Access restrictions
 are discussed in Section 7.9.1.
 9.4.1.5   Monitoring Requirements

 If a surface disposal site  does not have a liner and
 leachate collection system, then the Part 503 pollutant
 limits for surface disposal must be met (see Chapter 3)
 and must also monitor  ground water for nitrate. The
 owner/operator must then monitor the sewage sludge
 as required by Part 503 for the regulated pollutants.
 Surface disposal site owners must also monitor to en-
 sure that certain pathogen and vector attraction reduc-
 tion requirements are being met. In addition, air must be
 monitored for methane gas if sewage  sludge placed on
 an active sewage sludge unit is covered either daily or
 at closure. Monitoring requirements  are discussed in
 Chapter 10.
                                                   169

-------
 9.4.1.6   Pathogen and Vector Attraction
          Reduction

 Sewage sludge at surface disposal sites must meet the
 Part 503 operational standards for pathogen and vector
 attraction reduction, as discussed in Chapters. Regard-
 ing pathogens, Part  503 requires that the pathogen
 density be reduced through certain processes and also
 contains management practices that help ensure that
 pathogens will  not regrow.

 5.4.2  General Operational Procedures for
        Sewage Sludge Surface Disposal Sites

 Operational factors that are generally applicable to all
 sewage sludge disposal sites include:

 •  Environmental control practices

 •  Inclement weather practices
 •  Hours of operation

 9.4.2.1   Environmental Control Practices

 In many cases, environmental controls must be used at
 sewage sludge surface disposal sites. These environ-
 mental controls are described in  the following sections
 and outlined in Table 9-1.

 •  Spillage. Enroute and on-site spillage of sludge must
   be cleaned up as soon as possible.  Haul vehicles

Table 9-1.  Environmental Control Practices
  enroute to the disposal site should report even small
  spills to  the  operation supervisor,  so emergency
  clean-up crews can take prompt action. On-site spills
  should be controlled as much as possible. It is a
  good policy to have  lime on hand at all sludge dis-
  posal operations for spot application to spills if prompt
  clean-up  is not feasible. The  use of haul vehicles
  with baffles on them has been  used effectively to
  limit spills.

• Siltation and erosion. The presence of silt-laden run-
  off from the site is often the result of improper grading.
  Grades of 2 to 5 percent should be maintained where
  feasible to promote overland surface drainage, while
  minimizing flow velocities. Denuded areas should  be
  kept to a minimum during site operation. Ongoing
  construction and maintenance of sediment control
  devices (e.g., grass waterways, diversion ditches, rip-
  rap, sediment basins) are critical  for an environmen-
  tally sound operation. During site completion, proper
  final grading,  dressing,  and seeding prevent  long-
  term erosion; and siltation problems.

• Mud.  Mud is usually caused by  improper drainage
  but can be a problem at any site during heavy rains
  or spring thaws. To minimize the effect of mud on op-
  erations, access roads should be constructed of gravel.
  If practical, a wash pad  should be located near the
  exit gate to clean mud from transport vehicles.


Environmental
Problems
Spillage
Siltation and Erosion
Hud
Dust
Odors
Noise
Aesthetics
Health
Safety


E
5-
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Maintain Washrooms
for Personnel







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Maintain Fencing






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Maintain Buffer Area
Grass

X
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X
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X
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Proper Equipment Ma
tenance
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                                                 170

-------
• Dust.  Dust is usually caused by wind or the move-
  ments of haul vehicles and equipment. To minimize
  dust, access roads should be graveled. Also, areas
  that are covered with intermediate or final soil cover
  should be vegetated as soon after their completion
  as possible. As an alternative, water can be applied
  to dusty roads.

• Odors. Odors can be a serious problem at a sewage
  sludge surface disposal site  unless preventive steps
  are taken. The  sludge should  be covered  as fre-
  quently as necessary  to  minimize  odor problems.
  Lime or chemical masking agents can be applied to
  reduce odor problems. An effective means of reduc-
  ing odors is to limit storage of the sludge.  Ideally,
  storage of sludge should be abcomplished at the
  wastewater treatment plant.

• Noise. Noise sources  at surface disposal sites in-
  clude operating equipment and haul vehicles.  Gen-
  erally, the noise is similar to that generated by any
  heavy construction activity, and is confined to the site
  and the streets used to bring sludge to the  site. To
  minimize the effect, every effort should be made to
  route traffic through the least populated areas. Fur-
  ther, the site can be isolated so that the noise cannot
  carry to nearby  neighborhoods. The use of  earthen
  berms and trees as noise barriers can be very effec-
  tive. On the site, noise protection for employees will
  be governed by existing  Occupational Safety and
  Health Act (OSHA) standards.

 • Aesthetics. To make the surface disposal site publicly
  acceptable, every attempt should be made  to keep -
  the site compatible with its surroundings. During site
  preparation,  it is important to leave as many trees
  as possible to form  a visual barrier. Earthen berms
  can be similarly used. The use of architectural effects
  at the receiving area, the planting of trees along the
  property line, and confining dumping to designated
  areas will assist in the development of a sound op-
  eration. Additionally, every attempt  should be  made
  to minimize the size of the working  area.

 • Worker health.  Although  there is a possibility that
  pathogens will be present  in sludge, particularly  if
 - undigested, no health problems have been reported
   by site operators.  Nevertheless, personnel should
   use caution when transporting, handling, and covering
   sludge. Washing facilities  should be located  on or
   near the disposal site.

 • Worker safety. As  with  any  construction  activity,
   safety methods must be implemented in accordance
   with OSHA guidelines. Work areas and access roads
   must be well marked to avoid on-site vehicle mishaps.
9.4.2.2   Inclement Weather Practices

Prolonged periods of rainy weather or freezing tempera-
tures can impede routine operation of a sludge surface
disposal site. Anticipating the operational problems and
addressing contingency operations in the operation plan
will promote efficient operations. A listing of potential
inclement weather problems  and solutions has  been
included  in Table 9-2.


9.4.2.3   Hours of Operation

Hours of operation should coincide with hours of sludge
receipt. In this way, personnel and equipment are avail-
able to direct  trucks to  the proper unloading location;
assist if trucks become mired in sludge or mud; or cover.,
the sludge quickly to minimize  odors. If the operation
plan calls for daily covering of sludge, hours of opera-
tion should continue at  least 1/2 hr past the hours of
sludge receipt to allow for cleanup  activities.  Sludge
deliveries after hours at the surface disposal site should
be discouraged.


9.5   Equipment

A wide variety of equipment  is utilized at surface dis-
posal sites.  Equipment selected depends largely on (1)
the disposal method and design dimensions employed
and (2) quantity of sludge received.

Because equipment represents a  large capital invest-
ment and accounts for a large portion of the operating
cost, equipment selection should be based on a careful
evaluation of the functions to be performed and the .cost
and ability of various machines to meet these needs.
Contingency equipment for downtime and maintenance
may be necessary at larger sites. These may be rented
or borrowed from other  municipal functions.

Table 9-3 provides guidance on the suitability of equip-
 ment to perform selected sludge disposal tasks. Table 9-4
 provides typical equipment selections for seven opera-
tional schemes. These matrices are meant to give general
 guidance on the selection of sludge disposal equipment.
 It should be noted, however, that general recommenda-
tions on equipment selection can be misleading. In all
 cases, final selection should be based on site-specific
 considerations. Figures 9-12 through 9-15 illustrate typi-
 cal equipment used at surface disposal facilities.

 The importance of employing qualified and well-trained
 personnel at  sludge surface disposal sites cannot be
 overstated. Qualified personnel often  make the differ-
 ence between a well-organized, efficient operation and
 a poor operation. Information on staffing and personnel
 for surface disposal sites is included in Chapter 11.
                                                   171

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Table 9-2.  Inclement Weather Problems and Solutions
    Inclement
    Weather
    Conditions

    Het
   Cold
Sludge Loading
and Transport

Problem:  If hauling
great distances, wet
weather conditions
may increase liquid
content of sludge.

Solution:  Cover
transport vehicle.
                  Problem:  Sludge
                  freezes in haul
                  vehicles.

                  Solution;  Line
                  trucks with salt
                  water, straw, sand
                  or oil.   Do not
                  allow prolonged
                  exposure to cold
                  (park in garage).

                  Use exhaust to
                  heat the trailer.
 Site  Preparation

 Problem:  Maneuvera-
 bility  of equipment
 hindered in mud.

 Solution:  Plan  to move
 operation to an  acces-
 sible working area.

Problem:  Depressions
 accumulate water, may
draw flies, mosquitos.

Solution:  Grade area
to promote surface
runoff.  Use insecti-
cides only when neces-
sary.
                      Problem:  Deep pene-
                      tration of frost in
                      trench areas.

                      Solution:
                      - Construct trenches
                        during good weather
                        and save for cold
                        months.
                      - Do not remove snow
                        (acts as insulator)
                        or allow vehicles
                        to ride on trench-
                        ing areas (causes
                        frost to penetrate
                        deeped into the
                        ground).
                      -  Hydraulic rippers
                        or jackhammers  are
                        to be  used  as a last
                        resort.
 Sludge Unloading

 Problem:  Maneuvera-
 bility of transport
 vehicles hindered  in
 mud.

 Solution:  Place sand
 or grave! in  areas  to
 improve traction.   In-
 crease deoth  of  road
 mater-al.

 Problem:  Instability
 of tre.ncn walls .may
 cause  collapse while
 unloading.

 Solution:   Have  trans-
 port ve.nicle dump at
 trench  1ip and push
 sludge  into ,trench
 with equipment.

 Proble-n:  Mud and sludge
 accumulates  on haul
 vehicles and  equipment.

 Solution:  A  washing pad
 at the Deceiving area
will clean  vehicles.
  Sludge Handling
  and Covering

  Problem:   When
  mixing sludge
  with refuse or
  soil ,  need more
  mixing material.
                                                                                            Solution:   Ensure
                                                                                            sUT'TcTent supply
                                                                                            o* refuse  or soil
                                                                                            material .

                                                                                            Problem:  Ponded
                                                                                            water collecting
                                                                                            in trenches.

                                                                                            Solution:   Use
                                                                                            potable pump
                                                                                            to remove
                                                                                            excess water.
                         Prooleei:
                         freeze."
          Tailgates
                        Solution:  (1) Spray
                        ethylene slycol on
                        frozen parts.  (2) use
                        exhaust to heat frozen
                        parts.

                        Problem:  Previously
                        (fall season) muddy
                        roads fonr. severe ruts
                        and chuck holes.

                        Solution:  Regrade and
                        build before winter
                        freeze.
 problem:   Deep
 penetration  of
 frost  in  cover
 supply areas.

 Solution:  Accum-
 ulate  stockpile
 in  good weather.
 Ensjre supply  of
 cover  material;
 insulate piles
 with tarpaulin or
 hay.

 Problem;  Equip-
ment freeze-up.

Solution:   Trucks
or crawlers should
be well cleaned
of sludge  and
soil.
                                                    172

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Table 9-3.  Equipment Performance Characteristics









Equipment Name
Trenching Machine
Backhoe with Loader
Track Loader
Wheel Loader
Track Dozer3
Scraper
Dragl i ne
Gr.ader
Tractor with Disc
TRENCH

Narrow
Trench
o

* o
2
Vt
8 en
1 fc
01 >
ฃ- Q
G G
G
G F
- G
- G
- G

G



Wide
Trench
C "
o

U
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in
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CJ CT
1 fc
 >
t- O
1— 0
-

G F
F -
G G
G -
G


AREA FILL


Mound



en T-
"3 re en en
1C . en o> f- -r-
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F G F G G
G F G F F
- G - F G
G - F - -





Layer


o>
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a: en o> •ซ-•!—
c en s- i-
,- -r- -a > >
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10 Z 10 — 1 0




G G G - -
- G - G G
G - F G G
- - - G G


Diked
Contain-
ment
•
o
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G G
- F




ludge/
Soil

en
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ro
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1 'X 3 S
r— -i- rd O
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F - G F
- - F F
G F - G
- - F F
F - - -
- G - -

     G - Good.  Fully  capable of performing function listed.  Equipment could be selected  solely on basis of
     F = Fair.  Marginally capable of performing function listed.   Equipment should be selected on basis of
                full capabilities in other function.
     - = Not applicable.   Cannot be used for  function .listed
     a   Caterpillar D-6  generally is the largest track dozer appropriate for a sludge landfi.n.
 Table 9-4.  Typical Equipment Selection Schemes



Equipment
Trenching Machine
Backhoe with Loader
Excavator
Track Loader
Wheel Loader
Track Dozer
Scraper
Dragline
Grader
Tractor with Disc
.Total
1
Trench Method

Narrow Trench
,a 2ฐ 3c 4d 5e
1 2
11 \* 1
1
1ซ 1 1 2ซ




12235


Wide Trench
12345


1 1* 1 1*
1ป 1 1 2*
1* 1



12224

Area Fill Method

Mound
12345

1* 1* 1* 1
11111
1 1
1* 1 1
1* 1* 1



12455


layer
12345



1*
1 1 1 2* 2
1* 1* 1* 1



12234

Diked
Containment
12345



1 1* 1* 1 2*
1* 1 1
Till


12334

Co-disposal Hethodf

Sludge/Refuse
12345


I
1* 1 1




- - 1 12


Sludge/ Soil
12345


1* 1* 2*




1 1 1* 2* 2
] 1 2 4 5

         a  Scheme 1 - 10 wet tons/day
         b  Scheme 2-50 wet tons/day
         c  Scheme 3-100 wet tons/day
d  Scheme 4 - 250 wet tons/day
e  Scheme 5-500 wet tons/day
f  Additional equipment only
                                                                         * Hay not receive 100S utilization
                                                          173

-------
Figure 9-12. Scraper.
                  iSrCS^V^-*'"' ^S*V!lM!K*>-—-'j^d
                  rl^v^K.^sl^^i^
Figure 9-13.  Backhoe with loader.
                                             174

-------
Figure 9-14.   Load lugger.
 Figure 9-15..  Trenching machine.
                                                           175

-------
 and  air (outputs). The main concern with monitoring
 sewage sludge is  ensuring that  the nature and  fre-
 quency of sampling adequately characterizes the con-
 centration of pollutants in sludge. The main concern with
 environmental monitoring is ensuring that the number
 and location of sampling points are adequate to charac-
 terize background  levels (for ground water)  and that
 sampling is frequent  enough to determine whether a
 particular requirement is met.


 10.3.1  Parameters of Interest

 As noted  in  Section  10.2.1, the  main parameters of
 interest for monitoring at sewage sludge disposal sites
 include: (1) .arsenic, chromium, and nickel, which have
 been identified as the  main metals  of concern in sludge;
 (2) pathogens and  vector attraction  reduction; (3) ni-
 trates in the ground water; and (4) methane gas, which
 can reach explosive  concentrations  when sewage sludge
 is covered and anaerobic conditions develop in the sub-
 surface. Where a treatment works is  known to receive
 significant inputs of other types of pollutants from indus-
 trial sources,  then the number of inorganic and organic
 species that must be monitored might be larger.

 U.S. EPA (1992a) covers requirements for the monitor-
 ing, sampling, and  analysis of pathogens and vector
 attraction reduction  efforts under Part 503 in detail and
 should be consulted for further guidance. The remainder
 of this chapter focuses on  other  types of monitoring.
 Chapter 2  of U.S. EPA (1993a) also provides guidance
 on monitoring of sewage sludge for surface disposal.

 At  sites where leachate or  runoff  is collected  and  re-
 leased to  surface waters as a point source, NPDES
 permits may require monitoring of a number of parame-
 ters,  such as  chemical or biological  oxygen  demand
 (COD/BOD), turbidity, pH and selected chemical spe-
 cies.  At sludge surface disposal  sites arsenic,  chro-
 mium, nickel, pathogens,  and nitrates would be  likely
 additional parameters for leachate and surface water
 monitoring, because they  are monitored in other parts
 of the system.
                                                         10.3.2  Media To Be Sampled

                                                         Monitoring at sludge surface disposal sites may require
                                                         sampling of alf types of media: (1) solids or semisolids
                                                         for sludge characterization, (2)  liquids  in the form of
                                                         leachate, surface water, and ground water; and (3) air
                                                         to detect presence of methane. Sewage has to be moni-
                                                         tored if an active sewage sludge unit  does not have a
                                                         liner and leachate collection system, ground water has
                                                         to be monitored  unless a certification  is made, and air
                                                         has to be monitored if the unit is covered. Other special
                                                         considerations for monitoring of specific media are
                                                         addressed in Sections 10.4.2 (Ground  Water), 10.4.3
                                                         (Leachate and Surface Water), and 10,4.4 (Methane).


                                                         10.3.3  Sampling Locations

                                                         Sampling locations will depend on the type of media being
                                                         sampled. Sewage sludge can either be sampled during
                                                         loading or on the ground after dumping or spreading.1
                                                        Table 10-1  identifies recommended sampling points for
                                                        various types of  sewage sludge.  In general,  sampling
                                                         locations should  be as close to  the stage  before final
                                                        disposal as possible. Domestic septage can be sampled
                                                        from the container used to haul the domestic septage or
                                                        after placement  (the risk of penalties  for being out of
                                                        compliance after placement  apply here  as well). Section
                                                         10.4,1  addresses sampling of sludge in more detail.
                                                        Ground-water monitoring wells (Section  10.4.3) should be
                                                        located up- and down-gradient from the surface  disposal
                                                        site based on flow net analysis and other hydrogeologic
                                                        information obtained during  site investigations (Sections
                                                        6.4.3 and 6.5.2). Section 10.4.2 discusses monitoring well
                                                        network design further. Leachate collection systems and
                                                        ponds  for collection of surface water  runoff should  be
                                                        sampled at the point of discharge to surface waters. Meth-
                                                        ane gas monitoring devices,  if required,  should be placed
                                                        in each structure within the surface disposal site bounda-
                                                         Sampling after spreading poses the risk of penalties if samples
                                                        exceed pollutant limits and should only be done if pollutants do not
                                                        vary greatly in concentration and are known to fall well below pollutant
                                                        limits.
Table 10-1.  Chemical and Physical Parameters Typically Determined for Monitoring of Sewage Sludge Application Sites

Sample            Chemical and Physical Parameters

Ground Water       Field Measured Parameters for Sampling: pH, electrical conductivity, temperature, turbidity; Other Common
                  Parameters: Total hardness, total dissolved solids, chlorides, sulfates, total organic carbon, nitrate nitrogen, total
                  phosphorus, surfactants, selected metals (arsenic, chromium, nickel and others, if appropriate) or trace organics
                  where applicable, pathogens/indicator organisms.

                  Fecal conforms, total phosphorus, total nitrogen (Kjeidahl), dissolved oxygen, chemical/biological oxygen demand
                  (COD/BOD), temperature, pH, suspended solids.

                  Exchangeable ammonium nitrogen and nitrate-nitrite nitrogen, available phosphorus, pH, electrical conductivity,
                  organic carbon, exchangeable cations (calcium, magnesium, potassium, sodium), total and extractable metals—DTPA
                  or 0.1 N HCI (arsenic, cadmium, chromium, copper, nickel, zinc), cation exchange capacity, particle size distribution
	(texture), other known or suspected contaminants.
Source: Adapted from Granato and Pietz (1992).
Surface Water
Soil
                                                    178

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ries, and at site boundaries  based on prevailing wind
direction  (Section 10.4.4).

10.3.4   Sampling Frequency

The Part 503 regulation establishes frequency of sampling
to characterize sludge at surface disposal sites based on
the amount of sludge placed on a site, in a year (Table
10-2). If climatic conditions do not allow placement of the
sludge year-round, the number of sampling events should
be spaced over the period of active placement. For exam-
ple, if placement of sludge only occurs 6 months of the
year, and the minimum frequency is 6 times per year, then
sampling would need to occur once a month during the
period of active spreading. If  no previous sampling data
are available on the sludge to be disposed,  it may be
desirable to sample more frequently until enough data are
collected to determine the minimum number of samples
required to satisfy a 90 percent confidence limit for sample
representativeness (Section 10.4.1).
Ground-water sampling is usually done on a quarterly
basis, although specif ic state regulatory programs might
specify different intervals. When leachate or surface
runoff is discharged to surface water, the sampling inter-
val will be specified in the NPDES permit, which again
is typically four times a year. Air monitoring for methane
gas, when required, should be continuous.


10.3,5   Sample Collection and Handling
         Procedures

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
  sampling protocols are correctly followed.
Table 10-2. Frequency of Monitoring for Surface Disposal of Sewage Sludge
Parameter
Metals
Applies to
All Class A Pathogen
Reduction
Alternatives (PRA):
Fecal Coliform &
Salmonella sp.
Validity of Analytical Data over Time and When Sampling/Analysis Must Occur
METALS
Data remain valid for biosolids if ho significant change in volatile solids.
Determine monitoring' frequency in [accordance with monitoring frequency
requirements.
PATHOGENS CLASS A
Because regrowth can occur, monitoring should be done:
(a) sufficiently close to the tune of biosolids use so data are available and no additional
regrowth occurs before land application, or
(b) when biosolids are prepared for sale or give-away in a bag or other container for
land application, or
(c) when biosolids are prepared to meet EQ requirements.
Additional Information on Each Class A Pathogen Category
Class A PRA 1: Data remain valid as long as biosolids remain dry before use.
Thermal Treatment, Tj temperature, and moisture content should be monitored continuously to ensure
Moisture, Particle Size effectivene7s of treatment
& 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
Unknow Process
Class A PRA 5:
PFRP
Class A PRA 6:
PFRP Equivalent
Monitor to ensure that pH 12 (at 25ฐC) is maintained for more than 72 hours.
Once destroyed, enteric virus or viable helminth ova does not regrow. To establish a
process, determine with each monitoring episode until the process is shown to
consistendy achieve this status. Then continuously monitor process to ensure its
validity.
Once destroyed, enteric virus or viable helminth ova does not regrow. Monitor
representative sample of biosolids material:
(a) to be used or disposed, 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 continuously to show compliance with time and temperature or irradiation
requirements.
Monitor continuously to show compliance with PFRP or equivalent process
requirements.
                                                   179

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Tablป 10-2.  Monitoring Considerations for Key Parameters (continued)
Class BPRA1:
Fecal Coliform
aassBPRA2:
aassBPRA3:
Vector Attraction
Reduction (VAR) 1:
38% Volatile SoUds
Reduction (VSR)
VAR 2
for Anaerobic
Digestion:
If Cannot Meet VAR 1
Lab Test
VAR 3
for Aerobic Digestion:
If Cannot Meet VAR 1
Lab Test
VAR 4:
SOUR Test For
Aerobic Processes
VAR 5:
Aerobic xttJฐC
VAR 6:
Adding Alkaline
Material
VAR 7:
Moisture Reduction
No Unstabilized
Primary Solids
VAR 8:
Moisture Reduction
Primary Unstabilized
Solids
VAR 9:
Injection into Soil
VAR 10:
Incorporation into Soil
VAR 11:
Covered with Soil
Surface Disposal
VAR 12:
Domestic Septage
pH Adjustment
PATHOGENS CLASS B
Measure the geometric mean of 7 samples when used or disposed sufficiently close to
the time of use so that (i) data are available and (ii) no additional regrowth occurs
before land application.
Continuously monitor to show that biosolids are meeting the PSRP requirements.
Continuously monitor to show that biosolids are meeting the equivalent PSRP
requirements.
VECTOR ATTRACTION REDUCTION
Once achieved, no further attractiveness to vectors. If a batch process, determine VSR
for each batch. If for a continuous process, determine: VSR based on material being put
in and withdrawn. Monitor continuously to verify that biosolids axe meeting the
necessary operating conditions.
Once achieved, no further attractiveness to vectors. JK.a batch process, determine VSR
for each batch. If unable to show VSR, then conduct lab test Monitor continuously to
verify that biosolids are meeting the necessary operating conditions.
Monitor continuously to show that biosolids are achieving the necessary temperatures
over time.
Determine pH over time for each batch. Data are valid as long as the pH does not drop
such that putrefaction begins prior to land application.
To be achieved only by the removal of water. Data air valid as long as the moisture
level remains below 30%.
To be achieved only by the removal of water. Data are valid as long as the moisture
level remains below 10%.
No significant amount of biosolids remains on soil surface within 1 hour after injection.
Biosolids must be incorporated into soil within 6 hours after being placed on the soil
surface.
Surface disposed biosolids must be covered daily.
Preparer must ensure that pH is 12 for more than 30 minutes for each batch of domestic
septage treated with alkaline material
  Specification  of safety precautions, 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 type of sampling device. For de-
  watered sludge,  soil  sampling devices,  such  as
  scoops, trier samplers, augers, or probes can be used.
Stainless steel materials are best; chrome-plated sam-
plers should be avoided. For leachate and surface water,
sample containers can be filled directly at the points of
discharge or dippers used to transfer liquid to the con-
tainer. For ground water, a wide variety of sampling de-
vices are available. Because nitrate is the only monitoring
parameter specified in the Part 503 regulation, bailers will
probably be the simplest and least expensive sampling
device for ground-water sampling.
                                                   180

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• 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  in or 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 10-3 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 10-3 identifies these re-
  quirements for sludge samples. Unless analysis is
  done  in the field or in an  onsite  laboratory,  sludge
  samples are usually cooled to 4ฐC (i.e., packed in ice).
  Holding  times  vary with the constituent being ana-
  lyzed. For  example, the maximum holding time for
  nitrate is 24 hours unless the  sample is acidified, in
                          which case the holding time is a maximum of 28 days
                          (U.S. EPA. 1991c). The appropriate regulatory agency,
                          in coordination with the testing laboratory, should be
                          contacted to identify any specific sample preservation
                          procedures and holding times for all specific constitu-
                          ents 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.
Table 10-3.  Sampling Points for Sewage Sludge
                 Biosolids Type
              Anaerobically Digested
              Aerobically Digested
              Thickened
              Heat Treated
              Dewatered, Dried,
              Composted, or
              Thermally Reduced

              >  Dewatered by Belt
                Filter Press,
                Centrifuge, Vacuum
                Filter Press

                Dewatered by
                Biosolids Press
                (plate and
                frame)

                Dewatered by
                Drying Beds
                Compost Piles
                         Sampling Point
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 separate rapidly in welt-digested biosolids.	
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 biosolids 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 biosolids mass and at various depths.
Collect sample from biosolids 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 biosolids material (down to the sand).

Collect sample directly from front-end loader while biosolids are being transported or
stockpiled within a few days of use.
             Note: The term biosolids will be replaced with "sewage sludge* in the final document.
                                                       181

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Each type of media that is sampled should have a separate
written sampling protocol, unless sampling procedures
are the same for different media. U.S. EPA (1994a)
provides detailed guidance on sampling procedure for
sewage sludge. Most of the references cited in Table 6-7
in Chapter 6, address sample collection and handling
procedures in more detail. Keith (1992) provides a use-
ful general guide to development of environmental sam-
pling  protocols. Major sources  that  address  soil
sampling in greater detail include: U.S. EPA (1989b),
U.S. EPA  (1991b),  Boulding (1994), and U.S. EPA
(1992c). Ground-water sampling generally requires the
most complex  procedures  because of the need to
purge a well before sample collection (Section 10.4.2).
Major sources that  address ground-water sampling
procedures include:  U.S. EPA (1985), U.S. EPA (1991 c),
andU.S.EPA(1993b).

10.3.6   Sample Analysis Methods
Numerous procedures are available for chemical analy-
sis of environmental  samples. For example, there are
five major series of U.S. EPA methods: (1) EPA CLP
(contract laboratory program) for inorganic and  organic
analysis; (2) EPA 200 series  for water and wastes; (3)
EPA 500 series for organic compounds in drinking water;
(4) EPA 600 series (identified in 40 CFR, Part 146), and
(5) SW-846 methods for solid waste (U.S. EPA, 1986).
The American Society for Testing and Materials (ASTM)
publishes annually standard test methods for analysis
of water (Volumes 11.01 and 11.02) and wastes (Vol-
ume 11.04). The American  Pubic Health Association/
Water Environment Federation's compilation of methods
for analyzing water and wastewater is in its 18th edition .
(APHA, 1992). Furthermore, the  U.S.  Geological
Survey, as well as other federal  agencies, also have
developed  standard methods for  chemical  analysis
(mainly in its Techniques of Water Resource Investiga-
tions series). Also, state environmental agencies might
specify  their own methods for analysis of  certain con-
stituents. For example, New  Jersey requires testing of
sulfide reactivity of sewage sludge (personal communi-
cation, Cris Gaines, U.S. EPA Office of Water, April 1994).
Analytical  methods  in the  context  of environmental
regulatory programs can be grouped into the following
categories:
• EPA-approved methods have been published in the
   Federal  Register as the  benchmark method  for a
   specified regulatory purpose (i.e. reporting for NPDES
   or drinking water programs). Typically, EPA-approved
   methods required sophisticated fixed  laboratory
   facilities.
• EPA-accepted methods have been evaluated by EPA
   against an EPA-approved method and been found to
   be equivalent to the EPA-approved method. Manu-
   facturer claims that a method is EPA-accepted should
  be documented with a letter from EPA stating that the
  method has been evaluated by EPA and found to be
  equivalent. EPA-accepted methods are not published
  in  the Federal  Register  because additions  and
  changes to this category  are so  frequent that it is
  simpler to let manufacturers provide the necessary
  documentation to users.

• Other standard methods involve clearly defined pro-
  cedures and  protocols  defined by state  regulatory
  programs, other federal agencies  (such as the U.S.
  Geological  Survey)  or professional  organizations
  (such as the American Society for Testing and Mate-
  rials and the American Public Health Association). For
  specific purposes, EPA  may specify or recommend
  particular methods from these sources (See Table 10-5).

• Field screening  methods involve relatively simple
  qualitative (substance is present or absent in relation
  to a threshold level), semiquantitative (concentrations
  lie within a certain range), or quantitative methods
  that can be used in the field or a small laboratory.
  Chemical field screening  methods tend to be less
  expensive than  EPA-approved and EPA-accepted
  methods, but also less  accurate.  Potential  uses for
  these methods are discussed later in this Section.

EPA-Specified Methods

Table 10-4 identifies analytical methods for pathogens,
inorganic pollutants, and other sludge parameters that
are required by  the Part 503 regulation. Specific meth-
ods for sample preparation and analysis  for the metals
of interest for sewage sludge surface disposal are con-
tained in U.S.  EPA (1986)  as follows:  arsenic (EPA
Methods 3050/3051 and 7060/7061);  chromium (EPA
Methods 3050/3051 and 6010/7191/7190); and nickel
(EPA Methods  3050/3051  and 6010/7520). Although
both methods for 7060 and 7061 can be used to analyze
for arsenic, Method 7060 is often preferable  because
high concentrations of chromium, cobalt, copper, molyb-
denum, nickel,  or silver can cause analytical interfer-
ence in method 7061 (U.S. EPA, 1994b).

Other Standard Methods

Any state regulatory agency that has jurisdiction over a
surface disposal site should be consulted to determine
whether any additional analysis methods are required.
If conditions at a  particular site require analysis for
constituents for which there are not EPA or state-speci-
fied  methods,  the  appropriate ASTM or APHA/WEF
method may be selected (see above).

Field Screening Methods

Key considerations in sample analysis include ensuring
that  the methods  used for regulatory  reporting are
acceptable to the permitting authority and  minimizing
analytical costs. U.S. EPA-approved methods require
                                                  182

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Table 10-4.  Minimum Frequency of Monitoring for Surface Disposal of Sewage Sludge
Amount of Biosolids"
(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 15,000
Methane gas in air
Amount of Biosolids
(English units)
Ave. per day
>0to<0.85
0.85 to <4.5
4.5to<45
^45

per 365 days
>0to<320
320to4 ppmd >4 ppm

10:500
—
5-90
2-50
3-90

—
—

None
None
None
Photometer
RQ Flex Meter

Digestion (As, Cr);
spectrophotometer
Digestion, spectrophotometer
OTHER METHODS
Ion-Selective Electrodes6
ATI/Orion —
Hach Co. —
Solonet —
TM Analytic —

'— • —
— —
— —
— ' • —

0.1
0.1
0.1
0.1

Meter and reference electrode
Meter and reference electrode
Meter and reference electrode
Meter and reference electrode
Note: Manufacturer should be contacted for current status and documentation for EPA approval or acceptance.
* See Appendix C for addresses and phone numbers of manufacturers.
  Quant tests measure chromate, HACH wateriest measures Cr(VI) and Hach sludge tests are for total chromium.
0 EPA-accepted methods for NPDES reporting (water samples).
  EPA-approved method only if preceded by EPA-apprpved nitric acid digestion.
9 EPA acceptance pending for NPDWR reporting.
                                                             183

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extensive laboratory facilities, with relatively high capital
and operating costs, which means that analytical costs
tend to be high. Advances in the portability and accuracy
of instrumentation and techniques for analyzing environ-
mental samples are making chemical analysis in the
field or in small onsite laboratories an option that should
be carefully evaluated, in consultation with the appro-
priate regulatory authority, as a possible way to re-
duce  costs  associated  with chemical analysis. Such
methods can be used in two ways: (1) as an alternative
to sending samples to a laboratory where EPA-approved
or EPA-accepted methods can be used in the field or in
an on-site laboratory, and (2) for process control.

Most standard methods for sampling metals require use
of flame or graphite furnace atomic absorption spectros-
copy or inductively coupled plasma (ICP) atomic emis-
sion spectrometry, which require specialized training for
use. Laboratory analysis of arsenic,  chromium, and
nickel in a sample of sludge can be expected to cost as
much as $80 to $85. In contrast, semiquantitative col-
orimetric tests,  which often are able to detect concen-
trations in sub-ppm levels, are available for many metals
at a cost of less than $1.00 per sample. Table 10-5
identifies detection  limits for a number of  colorimetric
methods (field  screening methods) for arsenic, chro-
mium, nickel, and nitrate, the main inorganic pollutants
of interest in sewage sludge placed on an active sewage
sludge  unit.  The Quant tests  all use test strips that
change in color in response to a concentration of the
analyte being tested. EM Quant, Aquaquant, and Micro-
quant tests involve visual matching with color charts or
wheels.  Spectroquant and  Reflectoquant tests give
quantitative results using spectrophotometric  measure-
ments. Hach tests use chemical reagents, often in com-
bination with digestion  procedures, yield  quantitative
measurements  using a spectrophotometer. Hach (1991,
1992) provides  detailed information on test procedures
for waste and water analysis, respectively.

Table 10-5 provides summary information on other types
of field-portable instruments. Ion-selective electrodes
(ISE) able to measure concentrations of nitrate down
to concentrations of 0.1 ppm and approved by U.S.
EPA for monitoring drinking water quality is planned
for publication  in the Federal  Register by the end of
1994. Laboratory analysis of water samples for nitrate
generally cost  around $25 per sample. For an initial
investment of $1,500 to $2,500 for a nitrate electrode,
reference electrode, and meter, reagents for ISE tests
can be expected to cost from $0.50 to,$1.50 depending
on whether buffering solutions and reagents to reduce
interference from the presence of other species are used.
10.4 Media-Specific Monitoring
      Considerations
10.4.1   Sewage Sludge Characterization

Number of Samples. Monitoring of arsenic, chromium,
and nickel is required when surface disposal of sludge
is conducted without use of a liner and leachate collec-
tion system to protect ground water. The regulation un-
der 40 CFR 503.23 establishes pollutant limits for these
metals based on distance from  the  boundary of the
active sewage sludge unit to the property line of the
surface disposal site (see Table 3-5 in Chapter 3). Sam-
pling of sludge is required at the frequency specified in
Table 10-2, based on the annual amount of sludge dis-
posed. The minimum number of samples required to
show that concentrations  of  arsenic, chromium, and
nickel comply with the applicable pollutant limits in Table
10-6 at a 90 percent confidence interval can be readily
calculated if the average concentration and the standard
deviation of the  historical  sample set is known. The
following simple equations  are used for this procedure:
                                         (Eq.  10-1)
        Sample Mean (X) =
Sum of Data Values
        n
                                         (Eq. 10-2)
               Standard Deviation(s) =
  n(Sum of Squared Data Values) - (Sum of Data Values)
                                         (Eq. 10-3)
       Number of Samples =
   (Constant T)2s2
(Regulatory Limit - X)2
where:
            n = number of data values
    Constant T = appropriate value from Table 10-7
 Pollutant Limit = applicable value  in Table 10-6 or
                permit-specific value

The following steps are required to calculate the mini-
mum number of samples in a year  to demonstrate com-
pliance with the pollutant limits for  a sewage sludge:

Step 1. Calculate the mean and standard deviations for
arsenic, chromium,  and  nickel using historical data using
Equations 10-1 and 10-2. If historical data are not avail-
able, Table 10-8 can be used to provide initial values.

Step 2. Determine the Constant T f rom Table 10-7 based
on  the number of data values (n), and the appropriate
                                                  184

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Table 10-6.  Analytical Methods for Sewage Sludge

Enteric Viruses
Fecal Cobform
Helminth Ova
Inorganic Pollutants
Salmonella sp. Bacteria
Specific Oxygen Uptake Rate
Total, Fixed, and Volatile Solids
Percent Volatile Solids Reduction Calculation11

ASTM Designation: D 4994-89, Standard Practice for
Recovery of Viruses from Wastewater Sludges, Annual
Book of ASTM Standards: Section 1 1 . Water and
Environmental Technology, ASTM, Philadelphia, PA, 1992.
Part 9221 E or Part 922 D, Standard Methods for die
Examination of Water and Wastewater, 1 8th 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 1. 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. Claik, 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.
             • These analytical methods are required by the Part 503 rate.
             b This analytical raethcxl is provided as guidance in the Part 503 rule.

 pollutant limits for all three metals from Table 10-6 or
 site-specific values in the permit.

 Step 3. Calculate the required number of samples for
 each pollutant using Equation 10-3. The highest number
 of the three should be used for purposes of sampling.

 If the number of samples seems too high (which may be
 the case if the national values from Table 10-8 are used),
 several options may be available to reduce the number
 of samples: (1) during the design stage, it may be pos-
 sible to increase the distance from the boundary of an
 active sewage sludge unit to  the less stringent surface
 disposal site property line if the distance is less than 150
 ft, allowing recalculation of Equation 10-3 with pollutant
 limits (Table 10-6); or (2) collect a number of samples at
 relatively short intervals (days or weeks) and repeat
 Steps 1 through 3 above to see if a larger  historical
 sample size reduces the number of samples required as
 long as the frequency of monitoring in Part 503 is met.

 As the difference between the average concentration of
 a pollutant and the pollutant limit decreases, the number
of required  samples to demonstrate compliance in-
creases. When this difference is small, the number of
required samples might be so large as to make monitor-
ing prohibitive.  In such cases, the use of a  liner and
leachate collection system should be evaluated. Also, if
the historical data indicate the pollutant limits cannot be
achieved (e.g., mean chromium values for  100 MGD
facilities in Table  10-8 exceeds  the maximum allowed
pollutant concentration in Table 10-6), use of a liner and
leachate collection system is likely to be required.

Sample Collection. For "dry" sewage sludge (40 per-
cent solids) sampling is  best done when it is being
transferred,  usually on conveyors. U.S. EPA (1993a,
1994a) provide more  detailed  guidance on specific
sludge sample collection procedures. The most conven-
ient and most accurate scheme for sampling sludge will
generally be to sample haul truck loads at a frequency
that obtains the minimum number of samples calculated
using Equation 10-3 assuming the Part 503 frequency
of monitoring requirement is met. This frequency can be
determined  by dividing the  annual tonnage or cubic
yards of sludge by the calculated number of samples to
                                                   185

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Table 10-7.  Tabulated Values of Constant T for Evaluating Sludge for 90 Percent Confidence Interval
.*yVi*%^?iซ^ffiyg$-ri&tffi^
liM^ii^^^^^^^^
z
3
4
5
6
7
8
9
10
11
12
13
14
IS
16
17
18
19
20
21
22
23
24
25
26
23
30
inf.
y^&i&ijtii^^
K !*T^;5!;;SS?v?^ '; - •- * P*^* -{;*:?"$^ฃ">!:::
6.314
2.920
2.353
2.132
2.015
1.943
1.895
1.360
1.S33
1.312
1.796
1.782
1.771
1.761
1.753
1.746
1.74,0
1.734
1.729
1.725
1.721
1 . 717
1.714
1.711
1.708
1.703
1.699
1.645
determine how often haul trucks or spreaders should be
sampled. For example, if 250 cubic yards of sewage
sludge are hauled to the site in a year, in haul trucks with
a 25 cubic yard capacity, and ten samples are required,
then a representative sample from  each truck load
would be required.  If half that amount was hauled in a
year, then two representative samples representing the
front and back half of each truck would be required.

10.4.2  Ground-Water Monitoring

Monitoring for nitrates in ground water at sewage sludge
surface disposal sites is required unless a certification
is made by a ground-water scientist that ground water
will not be contaminated by the disposal  of sewage
sludge at the site (usually an option only if the site has
a liner and leachate collection system). If only nitrate
must be monitored (i.e., based on sludge or site charac-
teristics the regulatory authority does not require moni-
toring of other pollutants), it may be possible  to use
drive-point monitoring well  installations that are  less
expensive than standard installations,  as  discussed
later in this section. In-house sample analysis using
nitrate ion-selective electrodes also may be an economi-
cally attractive alternative to sending samples to  a labo-
ratory for analysis (see Section 10.3.6). The discussion
that follows assumes that only nitrate is being monitored
for regulatory reporting purposes and that the site rep-
                                                   186

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Table 10-8.  Alternative Values for Calculating Required Number of Sludge Samples for Metals Monitoring

Pollutant             Flow Group (MGD)             Mean (mg/kg)             Standard Deviation
Arsenic



Chromium



Nickel



>100 .
10 to 100
1to10
<1
>100
10 to 100
1 to 10
<1
>100
10 to 100
1 to 10
<1
7.71
12.08
9.72
9.93
461.41
281.40 ,
160.57
102.77
90.30
81.96
48.36
39.90
5.58
17.04
10.91
20.24
682.09
503.53
286.16
338.99
113.19
108.17
49.23
101.25
1.708
1.645
1.645
1.645
1.708
1.645
1.645
1.645
1.708
1.645
1.645
1.645
Source: Table 1-11, 55 FR 47229-47231, November 9, 1990.
resents a Type I hydrogeologic setting (Section 6.4.3).
If additional pollutants must be monitored, or aquifer
materials are  not suitable for drive-point installations,
conventional monitoring well design should be followed,
as covered in ASTM (1990), U.S. EPA (1991 a), Nielsen
and Schaila (1991), and references in Table 6-7 in Chap-
ter  6.  Use  of  drive-point installations for permanent
monitoring wells is still a relatively new concept in regu-
latory  applications,  so  the appropriate  regulatory
authorities should be consulted and provided any nec-
essary additional information to demonstrate that such
installations are an  acceptable  alternative to conven-
tional monitoring well installations.

Monitoring Network Design. Figure 10-1 summarizes
the process for designing  a ground-water monitoring
system. The flow net analysis described in Section 6.5.2
provides a basis for selecting locations for background
monitoring wells and downgradient wells for detection
monitoring.  For a simple Type I hydrogeologic setting,
monitoring wells would be set in the unconfined aquifer
with a minimum of two upgradient background monitor-,
ing wells (Figure 10-2), with  the location and number of
downgradient monitoring wells depending on flow paths
and  the size  of the site and any specific regulatory
requirements addressing the number of wells. Flow net
analysis will guide the depth of monitoring wells and the
length of well screen to be  used.  As noted in Section
6.5.2, failure to use flow net analysis for placement of
monitoring wells and determining screened intervals can
easily result in samples that miss any pollutant plume
that develops.

Monitoring Well Installation. Typical monitoring well
installations in  unconsolidated materials  are drilled us-
ing a hollow-stem  auger and constructed of PVC pipe
and well screen with filter-pack and grouting to seal the
 annular space around the well  pipe  (ASTM,1990).  If
 nitrate  is the only analyte of interest for ground-water
 monitoring, as specified in the Part 503 regulation, then
 alternative, less-expensive approaches might be able to
 satisfy monitoring requirements. Sample bias as a result
 of sorption or leaching of well screen and casing mate-
. rials is not a concern with nitrate because it is an anioh,
 which means that small-diameter (typically 1 inch or less
 outer diameter) metal  drive pojnts and casing materials
 can be used for installation of monitoring wells in uncon-
 solidated materials.  Basic elements of such an installa-
 tion include: (1) a slotted drive point (stainless steel is
 generally  preferable  for permanent  installations  be-
 cause  it is  more resistant to corrosion);  (2) a metal
 casing that is either cut to length or added as extensions
 until the desired depth is reached; and (3) a cap and
 protective containment structure to  prevent accidental
 damage to the aboveground portion of the installation.
 Possible additional  elements of the installation many
 include: (1) filter  material, such as Vyon, to prevent soil
 particles from entering the openings in the drive point
 or use  of porous stainless steel (10 to 20 micron open-
 ing), and (2) tubing that runs inside to the.casing of the
 welj point to eliminate contact between sample water
 and the casing.

 Methods of installation include the methods and equip-
 ment described in Section 6.4.3 in Chapter 6 for instal-
 lation of piezometers:  (1) handheld power driver (Figure
 6-2), (2) hydraulic probes (Figure 6-3),  (3) hand-oper-
 ated weighted drivers (Figure 6-8a), and (4) crank-driven
 drivers (Figure 6-8b).  In addition, vibratory drive meth-
 ods that adapt high-frequency hammer drill technology
 can be  used for very rapid installation of  pre-cut riser
 sections up to a maximum length of 21 ft (Figure 10-3).
 Depths of 30 ft  can  often be attained in nongravelly
 unconsolidated materials using the methods described
                                                   187

-------
                en
                1
                I
        w
        en

       I
       a*
       1
               en
               d
               u
I
Z
T
                         CONCEPTUAL
                             MODEL
                           FLOW NET
                        CONSTRUCTION
                        PLOT FACILITY
                           FEATURES
SELECT TARGET
 MONITORING
     ZONES
                            LOCATE
                        BACKGROUND
                            WELLS
                            LOCATE
                      DOWNGRADIENT
                            WELLS
                            VERIFY
                         LOCATIONS
   INSTALL
 DETECTION
MONITORING
    WELLS
     TEST
    SYSTEM
                           GEOLOGY / HYDROGEOLOGY

                        •  Surfacซseotogy (topography and type /depth of oveiburden
                        • Litnology and thickness of aquifer
                        • Type of geologic formation (local stratigraphy and structure)
                        • Recharge/ discharge areas
                        * Aquifer/confining unit(s) hydraulic conductivity and porosity

                           GROUND-WATER FLOW DIRECTIONS
                          Piezometeric anoYor potwttiorrotrie heads
                          Relative hydraulic heads between units
                          Three-dimensional flow directions using flow lines and equipotentials
                          Interconnection of aquifers
                          rates of ground-water movement

                          FACILITY FEATURES
                        • Bast map features
                        • Crosa-ซaetians with lithology
                        • Facility basegrades established and compared with now paths
                                                  TARGET MONITORING ZONES
                                                • Uppermost aquifer established
                                                • AH reasonable Row paths identified
                          AMBIENT WATER QUALITY

                        • Upgradient design - simple geology and heads
                        • Background Design - Complex geology or heads
                        • Number should have statistical basis
                                                  BASIS FOR DESIGN
                        • Geology and permeable awies
                        • Row net analysis
                        • Target monitoring zones
                        • Fadity waste boundaries

                         LOCATION CRITERIA

                        • State and Federal requirements
                        • Permit requirements
                        • Between waste areas and downgradkmt receptore
  HELD INSTALLATION OF WELLS

  Use ASTM standards (D-15092)
  Update conceptual nyaro^jeotogtc model
  Document Installation
  TEST AND OPERATE SYSTEM

• Performance test all welte
• Use operation and mamanee procedures
• Close and decommission inoorrectty placed wells
Figure 10-1.  Flow diagram of monitoring system design (Sara, 1994).
                                                188

-------
                         SELECTION OF BACKGROUND
                           WEtl SAMPLING SCHEME
    USE ALL HISTORIC
   PARAMETER VALUES
    2 YEAR FIXED
HISTORICAL WINDOW
2 YEAR MOVING
   WINDOW
                                        8 OR MORE BACKGROUND WELLS IN SYSTEM
                                        ป Calculate a Haw Totoranea Interval Each Quarter
        4 to 7 WE
        2 to 4 WEI
       1 BACKGROUND
       WELL IN SYSTEM
         NUMBER OF
     BACKGROUND WELLS
         IN SYSTEM
         WITH 4 TO 7 BACKGROUND WELLS IN SYSTEM
      •*" • Conduct Quarterly Monitoring
         • Calculate a Yoariy Totorenc* Interval
         2 TO 4 BACKGROUND WELLS IN SYSTEM
         ป Quarterly Monitoring Until 19 Sampfe* ara Taken
         • UaaaHHiatoricValuaafQrTolanmc* Intervala
             INSTALL ADDITIONAL "UPGRADIENT"-
           BACKGROUND WELLS OR YOU WILL NEVER
                PASS ANY STATISTICAL TEST HI
       RCCOMMENDKD BACKGROUND SAMPLING SCHEME
Figure 10-2.  Guidelines for background well sampling based on number of wells (Sara, 1994).
                                        189

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       Screen
                    MicroWell Schematic
                            Diagram
                    2" x 0.015"
                   Screen Slots
       Sump

       Drive
       Point
 Figure 10-3.  Micro Well schematic diagram; standard pipe Is
            0.62 Inches Internal diameter and 0.82 Inches
            outer diameter (courtesy of Pine & Swallow Asso-
            ciates).

 above.  In unconfined sandy aquifers, depths of 100 ft
 are readily obtainable. Vibratory drive installations have
 penetrated  to a maximum depth of  180 ft (personal
 communication, John Swallow, Pine & Swallow Associ-
 ates, Groton, MA, April 1994). Solinst Canada's product
 literature reports that a Waterloo drive-point piezometer
 using a power-driven drive-hammer has been installed
 at a depth of 275 ft in lacustrine clay in New Mexico.
 Costs of drive-point monitoring well installations can be
 expected  to range from  30 to  50 percent lower than
 conventional hollow-stem auger monitoring well instal-
 lations.  Table C-1 in Appendix C identifies manufactur-
 ers and distributors of well and piezometer drive points
 and drive  equipment.

 Sample Collection. The  narrow diameter of the above
 monitoring well installations restricts sample collection
 to two main methods: (1)  peristaltic suction lift pump for
 depths of 25 or 30 ft; (2) WaTerra inertial pump to depths
 of 100 ft (depths up to 250 feet can be sampled in 2- to
 4-in. wells); (3)  portable Solinst  triple tube  gas-drive
 sampler to depths up to 150 ft; and (4) small-diameter
 bailers (any depth). Specialized sampling techniques
 include (1) the BAT system, which uses evacuated sam-
 ple containers and a disposable double-ended hypoder-
 mic needle for sample collection, and  (2) the Waterloo
 drive-point double valve pump, which  includes a dedi-
cated positive displacement gas-drive sampler  inside
the  drive point device.
 Because drive-point installation results in minimal dis-
 turbance of the aquifer materials, if any, well develop-
 ment is required  before samples are collected. If the
 drive point includes filter material, then well develop-
 ment should not be necessary. If the drive point is open
 slotted, then some soil grains less than the diameter of
 the slotting can enter the point,  especially if vibratory
 drilling is used. For shallow installations (less than 25 ft)
 this material can be removed by using a peristaltic pump
 and inserting polyethylene tubing to the sediment/water
 interface. Deeper installations will require use of a bailer
 or WaTerra type  inertial pump and surging  action to
 suspend the sediment for collection in the bailer.

 The  narrow diameter of the drive pipe (generally less
 than 1 inch) means that drive-point installations will have
 less  stagnant water in the  well  between  sampling
 events, and the lack of filter pack or grout  means that
 aquifer chemistry outside the well is minimally affected
 compared to conventional monitoring well installations.
 Consequently the amount of time required  for purging
 before a  sampling event also will  be reduced. While
 purging, pH, conductance, and temperature should  be
 monitored until  they reach  a consistent endpoint  (no
 upward or downward trend), at which  point the sample
 should be taken.  Table  C-1 in Appendix C  identifies
 sources of field  instrumentation for ground-water sam-
 pling. If nitrate ion-selective electrodes are used to ana-
 lyze samples, multiparameter instruments are available
 that would allow monitoring of purge parameters and
 measuring nitrate concentration with the same meter.

 70.4.3  Leachate and Surface  Water
         Monitoring

 If  a liner  and  leachate collection system are used  to
 prevent migration of pollutants into the ground water, the
 disposition of the leachate will determine what kind of
 monitoring will be required. Discharge as a point source
 to surface waters will require  an NPDES permit, with the
 permit specifying what parameters must be  monitored.
 Table 10-1 identifies commonly monitored parameters.
 As discussed in Section  10.3.6, depending  on the pa-
 rameters that must be monitored,  use of wet chemistry
 field test  kits or a small onsite laboratory  may  be a
 cost-effective alternative to sending samples to an out-
 side laboratory. For example, there are 6 Hach methods
 that are U.S. EPA approved, and 35 Hach methods that
 are accepted by U.S. EPA for purposes of NPDES re-
 porting (Hach Company, 1989).2 The appropriate regu-
 latory authority should always be consulted to determine
whether a specific proposed method would be accepted
for regulatory reporting.  If leachate  is  discharged to a
 As noted in Section 10.3.6, the manufacturer test kits and equipment
should be contacted for information on the current status of EPA
acceptance or approval and asked to provide the appropriate docu-
mentation.
                                                  190

-------
POTW, some monitoring might be required or appropri-
ate for process control. Because precise measurements
are usually not required for this purpose, use of col-
orimetric test strips as described in Section 10.3.6 might
be a useful option.                                  ',

Surface runoff from the sludge surface disposal site that
is collected and discharged as a point source will require
an NPDES permit. As with leachate, the permit will
specify what parameters are to be monitored. It may be
desirable to monitor any surface runoff from the active
sewage sludge unit  that is not  controlled as  a point
source to see if pollutants of concern are moving offsite.
Use of Quant test strips (Table 10-5) would be'a rela-
tively inexpensive way to determine the concentration of
arsenic, chromium, nickel,  and nitrate in surface runoff.

10.4.4   Monitoring Air for Methane Gas

Whenever sewage sludge  placed on an active sewage
sludge unit is covered daily or at closure, continuous
monitoring of air  for methane gas is required  in all
structures within the  site properly line and at site prop-
erty lines. Methane gas concentrations within any struc-
ture must be less than 25 percent of the lower explosive
limit (LEL), which is the lowest percentage by volume of
methane gas in air that supports a flame at 25ฐC and
atmospheric pressure.  For methane, the LEL is 5 per-
cent. At the site property line, the LEL is the regulatory
limit (i.e., concentrations are not allowed to exceed the
LEL in air at the property  line), (See Section 7.8.2 for
additional information on control of explosive gases con-
trols.)
Two main  technologies are available for methane gas
monitoring: (1) metal oxide sensors  (MOS), also called
catalytic oxidation, semiconductor, or solid state detec-
tors; and (2) Pellistor/Wheatstone Bridge sensors. The
first type tend to cost  less but are less accurate (i.e.,
usually do not provide  quantitative readings of concen-
trations), more difficult to calibrate, and are quite sensi-
tive to changes in  humidity. Pellistor/Wheatstone Bridge
sensors are recommended for  use when monitoring
methane gas concentrations in  air  inside a structure.
The electrical  response of the  Wheatstone bridge is
 linear with concentration, which allows accurate meas-
 urement at low concentrations. Sensors with a 4 to 20
 milliamp (mA) signal range are recommended. Calibrat-
 ing the sensor so that 4 mA equals zero provides assur-
 ance that  the sensor is operating because any power
 failure will result in a negative reading.

 There are several rules of thumb for determining how
 many sensors are required for a building. Smaller build-
 ings with multiple rooms generally should have a sensor
 for every 1,500 cu ft of volume. For larger, open build-
 ings, spacing of sensors  100 to 150 ft on  center will
 generally be adequate. Sensors should be mounted on
 the highest point of a ceiling, and if outside air circulates
through the structures, they should tend to be offset
toward the downwind side of the structure (generally the
east side). Sensors will provide maximum safety if they
are installed so that methane concentrations of 10 per-
cent LEL will cause a fan with a timer to automatically
turn on to improve air circulation (the timer prevents the
fan from being turned on and off repeatedly if concen-
trations fluctuate around 10 percent LEL). The sensor
should be designed to sound a horn or turn on a warning
light if methane concentrations reach 20 percent LEL so
that action  can be taken to reduce methane levels be-
fore the 25 percent limit in the Part 503 regulation  is
reached. Pellistor/ Wheatstone Bridge sensors should
be calibrated every 30 to  90 days to ensure proper
functioning. The installed cost of indoor installations for
Pellistor/Wheatstone Bridge sensors can be expected to
fall in the range of $1,000 to $1,500 per sensor.

Because methane gas is considerably less dense than
air (specific gravity  0.5 percent) outdoor methane gas
releases will tend to rise rather than travel laterally to
site property lines unless there are exceptionally strong
winds. It is highly unlikely that methane gas concentra-
tions will reach anything approaching the LEL at sewage
sludge surface disposal site property lines, but the most
likely place to measure maximum concentrations would
be downwind (generally east) of the area where sludge
amounts are thickest. Initially, a single installation at the
downwind  point at which methane gas concentrations
are expected  to be highest should be adequate. The
sensor should be set at about 6 ft above ground level
and will require electrical service unless the site is very
remote, in  which case rechargeable batteries would be
required. The sensor should be set to sound an audible
alarm  if methane gas concentrations reach 20 percent
LEL. If site property line sensor readings repeatedly
exceed 10 percent LEL, some consideration should be
given  to installing  additional sensors along the down-
wind perimeter.
Table  C-1  in Appendix C  provides a selective list of
manufacturers of  gas monitoring  instruments.  The
March 1994 issue of Pollution Equipment News (8650
Babcock Blvd., Pittsburgh, PA 15237-9915; 800/245-3182)
provides a more detailed listing with information on gas
detection equipment available from more than 90 manufac-
turers. The gas detection selection chart, which is updated
annually, can be obtained by contacting Rimbach Publishing
 at the  location and phone number given above.

 10.5  Analysis and Interpretation of
       Sample Data

 70.5.1  Sewage Sludge Characterization Data

 When arsenic, chromium, and nickel concentrations are
 monitored, each new set of sample results should first
 be checked against the applicable limits in Table 10-8.
                                                   191

-------
 Assuming that analytical results fall  within acceptable
 levels, the only other type of analysis is that at least once
 a  year the  procedures described  in  Section  10.4.1
 should be repeated adding in the previous year's ana-
 lytical results to recalculate sampling frequency for the
 upcoming year.


 10.5.2   Ground-Water Sampling Data

 As shown in Figure 10-2 a minimum of two background
 monitoring wells are required for valid  statistical com-
 parison of background and downgradient monitoring re-
 sults. If fewer than four background monitoring wells are
 used, typically the case at sewage  sludge surface dis-
 posal sites, quarterly monitoring until  16 samples have
 been taken is required before monitoring data results in
 downgradient wells can be properly interpreted (Sara,
 1994). The types of statistical tests to determine whether
 nitrate has entered the ground-water system as a result
 of  sludge disposal would be the same  as for a RCRA
 facility  and are described  in U.S.  EPA (1989a). U.S.
 ERA'S GRITS/STAT software (U.S. EPA, 1992b) can be
 used to store monitoring data and run the statistical tests
 recommended in U.S. EPA (1989a).  The required  re-
 sponse if nitrate contamination is detected will depend
 on the background ground-water quality and policies of
 the permitting agency.


 10.5.3   Other Data

 Leachate and surface water sampling  data generally do
 not require statistical analysis. If sampling  is used  for
 NPDES reporting,  then sample  results are compared
 against the limits specified in the permit. Sampling of
 leachate  for process control when  discharged  to  a
 POTW, as discussed  in  Section 10.4.3 might require
 some simple statistical  analysis to compute average
 values  and the range of  values  examined to see
 whether they are within desired limits. Methane gas
 monitoring systems in structures should  be designed
to be self-regulating, as  described  in Section 10.4.4,
and will not normally require collection or analysis of
sensor readings.


10.6 References

 1.  American Public Health Association (APHA).  1992.  Standard
    methods for the examination of water and wastewater, 18th edi-
    tion. Washington, DC.

 2.  American Society for Testing and Materials (ASTM). 1990. Rec-
    ommended practice for design and installation of ground-water
    monitoring wells in aquifers, Vol. 4.08. D5092-90. Philadelphia, PA.

 3.  Boulding, J.R.  1994. Description and sampling of contaminated
   soils: A field guide, revised and expanded, 2nd ed. Chelsea, Ml:
   Lewis Publishers.
 4. Granato, T.C., and R.I.I. Pietz. 1992. Sludge application to dedi-
    cated beneficial use sites. In: Luel-Hing, C., D.R. Zenz, and R.
    Kuchenrither, eds. Municipal sewage sludge management: Proc-
    essing, utilization and disposal.  Lancaster, PA: Technomic Pub-
    lishing Co. pp. 416-454.

 5. Hach Company. 1992. Water analysis handbook, 2nd ed. Love-
    land,  CO:  Hach Company. [See Appendix C for address and
    phone number.]

 6. Hach Company. 1991. Handbook for waste  analysis, 2nd ed.
    Loveland, CO: Hach Company. [See Appendix C for address and
    phone number.]

 7. Hach Company. 1989. Using Hach methods for regulatory report-
    ing and process control.  Loveland, CO: Hach Company. [See
    Appendix C for address and phone number.]

 8. Keith, L.H. 1992. Environmental sampling and analysis: A prac-
    tical guide. Chelsea, Ml: Lewis Publishers. (In cooperation with
    ACS  Committee on Environmental Improvement.)

 9. Nielsen, D.M., and R. Schaila. 1991. Design and installation of
    ground-water monitoring wells. In: Nielsen, D.M., ed. Practical
    handbook of ground-water monitoring. Chelsea, Ml:  Lewis Pub-
    lishers, pp. 239-331.

 10. Sara, M.N. 1994. Standard handbook of site assessment for solid
    and hazardous waste facilities. Boca Raton, FL: Lewis Publish-
    ers.

 11. Sieger, R.G., R.C. Carlson, L.  Patterson,  and G.J. Hermann.
    1992. Ground water, soil, and vegetation monitoring for two land
    application projects in Texas. In: The future direction of municipal
    sludge (biosolids) management: Where we are and where we're
    going. Poster session proceedings, Vol.  II. Water Environment
    Federation, pp. 163-172.

 12. U.S. EPA. 1994a. POTW sludge sampling and analysis guidance
    document, 2nd ed. Washington DC. [1st edition published 1989.
    (NTIS PB93-227957)]

 13. U.S. EPA.  1994b. Surface disposal of sewage sludge: A guide
    for owners/operators of surface disposal facilities on the monitor-
    ing, recordkeeping, and reporting requirements of  the federal
    standards for the use or disposal of sewage sludge, 40 CFR Part
    503. EPA/831/B-93/002C.

 14. U.S. EPA.  1993a. Preparing sewage sludge for land  application
    or surface disposal: A guide for preparers of sewage sludge on
    the monitoring, recordkeeping, and reporting requirements of the
    federal standards for the use or disposal of sewage sludge under
    40 CFR Part 503. EPA/831/B-93/002a.

 15. U.S. EPA. 1993b. RCRA ground water monitoring: Draft technical
    guidance. EPA/530/R-93/001 (NTIS PB93-139350).

 16. U.S. EPA.  1992a. Environmental regulations and technology:
    Control of  pathogens and vector attraction in sewage sludge
    (including  domestic  septage)  under 40  CFR   Part 503.
    EPA/625/R-92/013.

 17. U.S. EPA. 1992b. User documentation:  A ground-water informa-
    tion tracking system with statistical analysis capability GRITS/
    STAT,  Version 4.2. EPA/625/11-91/002.

18. U.S. EPA. 1992c. Preparation of soil sampling protocols: Sam-
    pling techniques and strategies. EPA/600/R-92/128 (NTIS PB92-
    220532). (Supersedes  1983 edition titled:  Preparation  of soil
    sampling protocol: Techniques and strategies, EPA/600/4-03/020
    [NTIS  PB83-206979].)
                                                       192

-------
19. U.S. EPA. 1991 a. Handbook of suggested practices for the design
    and installation of ground-water monitoring wells. EPA/600/4-89/
    034. (Also published in 1989 by National Water Well Association,
    Dublin, OH, in its NWWA/EPAseries, 398 pp. Nielsen and Schalla
    [1991] contain a more updated version of material in this hand-
    book that is  related to design and installation of ground-water
    monitoring wells.)

20. U.S. EPA. 1991b. Description and  sampling of contaminated
    soils: Afield pocket guide. EPA/625/2-91/002.

21. U.S. EPA. 1991c. Geochemical sampling of subsurface solids
    and ground water. In: Site characterization for subsurface reme-
    diation (Chapter 9). EPA/625/4-91/026.

22. U.S. EPA. 1989a. Statistical analysis of ground-water monitoring
    data at  RCRA facilities, interim final guidance. EPA/530/SW-
    89/026 (NTIS PB89-151047),  plus September 1991 Addendum.
    [Incorporated into GRITS/STAT.]'
23: U.S. EPA. 1989b. Soil sampling quality assurance user's guide,
    2nd ed. EPA/600/8-89/046 (NTIS PB89-189864).

24. U.S. EPA. 1986. Test methods for evaluating solid waste, 3rd ed.
    EPA/530/SW-846 (NTIS  PB88-239223). First update, 3rd  ed.
    EPA/530/SW-846.3-1 (NTIS PB89-148076). 2nd edition was pub-
    lished in 1982 (NTIS PB87-1200291); current edition and updates
    available on a subscription basis from U.S. Government Printing
    Office, Stock #955-001 -00000-1.
25. U.S. EPA.  1985.  Practical  guide  for ground-water sampling.
    EPA/600/2-85/104 (NTIS PB86-137304). Also published as ISWS
    Contract Report 374, Illinois State Water Survey, Champaign, IL.
                                                               193

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                                           Chapter 11
          Recordkeeping, Reporting, and Management for Surface Disposal
11.1  General

This chapter describes the recordkeeping and reporting
requirements when sewage sludge is placed on a sur-
face disposal site under the Part 503  rule, including
records of costs and activities. Regulatory requirements
for  recordkeeping are covered in Section 11.2. This
discussion covers requirements for owners/operators of
active sewage sludge units with, and without, liners and
leachate  collection systems, and for  preparers of sew-
age sludge. The U.S. EPA document, Surface Disposal
of Sewage Sludge: A Guide for Owners/Operators of
Surface Disposal Sites on the Monitoring, Recordkeep-
ing, and Reporting Requirements of the Federal Stand-
ards for the Use or Disposal of Sewage Sludge 40 CFR,
Part 503 (1994a), and U.S.  EPA (1993b) outline addi-
tional information on the recordkeeping requirements for
operators of active sewage sludge units and preparers
of sewage sludge, respectively.

This chapter also discusses the management of surface
disposal  sites,  including management organization  and
staffing/personnel. The management system required for
a surface disposal site will be influenced by such factors
as the type of active sewage  sludge unit, the volume and
type of sludge received, and site conditions. The goals of
the manager of a sewage disposal site should be to oper-
ate the site in a manner that is economically sound and
adequately protects public health and the  environment.
These goals must be carefully balanced as regulations
become  more stringent and operating costs increase.

The management of a surface disposal site involves a wide
 range of  activities. The site manager is responsible for:

 • Day-to-day operation

 • Equipment maintenance and replacement

 • Regulatory compliance

 • Site security

 • Public relations
 •  Personnel management and training

 •  Recordkeeping

 •  Fiscal management
11.2  Regulatory Requirements for
      Recordkeeping


11.2.1  Part 503 Recordkeeping
        Requirements for Owners/Operators
        of Active Sewage Sludge Units With
        Liners and Leachate Collection
        Systems

Owners/operators of active  sewage sludge units are
required to keep records of management practices and
applicable vector attraction  reduction  requirements.
They must also keep a certification statement as shown
in Figure 11-1. The records  must be maintained for 5
years and be readily available to State and EPA inspec-
tors. The owners/operators should be aware that failure
to keep adequate records is  a violation of the Part 503
regulation and subject to penalty under the Clean Water
Act (CWA).

11.2.1.1   Records of Management Practices

Owners/operators must ensure that the management
practices (requirements for the siting, design, and op-
eration of active sewage sludge units to ensure protec-
tion of human health and the environment) are met at
each active sewage sludge unit. In addition, compliance
with these practices must be documented in detailed
records and kept for 5 years. Compliance with siting and
design requirements must be documented only once.
Compliance with the operating requirements must be
recorded on a continual basis, the frequency of which
depends on the specific requirements.

Some of the information gathered to support one man-
agement practice may overlap with the information re-
quired for others. For example, geotechnical investigations
are required to demonstrate compliance with the re-
 quirements for three management practices: seismic
 impact zone, fault zones, and unstable areas. Geotech-
 nical  investigations, which are necessary for any con-
 struction project, evaluate foundation soils and bedrock
 and characterize the hydrogeology of a site. Maps or draw-
 ings should be obtained or produced as part of compli-
 ance with the management practices. A combination of
                                                 195

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                            "I certify, under penalty of law, that the management practices in ง503.24 and
                            the vector attraction reduction requirement in [insert one of the requirements in
                            ง503.33(b)(9) through ง503.33(b)(l 1), if one of those requirements is 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 management practices [and the vector attraction reduction requirements, if
                            appropriate] have been met I am aware that there are significant penalties for
                            false certification, including the possibility of fine and imprisonment"
                           Signature
                                                                     Date
  Figure 11-1.  Certification statement required for recordkeeping: Owner/Operator of surface disposal site (U.S. EPA, 1994b).
 commercially available and customized maps and plans
 can help demonstrate compliance.

 Endangered or Threatened Species

 Part 503 prohibits the placement of sewage sludge on
 an active sewage sludge unit if it is likely to  adversely
 affect an endangered or threatened species or its des-
 ignated  critical  habitat (see  Section 4.2.1.1).  The
 owner/operator should retain all documentation to dem-
 onstrate that the site was evaluated for potential effects
 on endangered or threatened species and their habitat
 and that necessary protective measures were identified
 and  implemented.  For example, this  documentation
 should list endangered or threatened species in the area
 or document that none exists and briefly describe how
 the  endangered or threatened species and its critical
 habitat are protected.

 Usually, documentation will need to be performed only
 once. If the active sewage sludge unit begins to pose a
 risk to endangered or threatened species, however, the
 owner/operator should contact the permitting authority
 or the Fish and Wildlife Service.

 Base Flood Flow Restrictions

 Part 503 prohibits  an active sewage sludge unit from
 restricting the flow of a base flood (see Section 4.2.1.2).
 The following types of information may be used to de-
 scribe how this management practice is met:

 •  A flood plain insurance rate map (available from the
   Federal Emergency Management Agency) with the site
   location accurately marked to demonstrate whether
   it is within the 100-year floodplain. Other sources of
   this information include the U.S.  Army Corps of Engi-
   neers, the U.S.  Geological Survey (USGS), Bureau
   of Land Management, Tennessee Valley Authority, and
   local and State agencies.

•  If the unit  is in the 100-year floodplain, the design
  details and management  practices that will  prevent
  restriction of the flow of the  base flood,  including a
   plan view, a cross section of the unit, and calculations
   used to determine that  the site  will not restrict the
   base flood flow.

 • If the unit is in the 100-year floodplain, evaluation of
   the impact of the unit based on predictive models,
   such as the HEC series  generated by the U.S. Army
   Corps of Engineers.

 Seismic Impact Zones

 Part 503 requires active sewage sludge units located in
 seismic impact zones to be designed to withstand the
 maximum recorded ground level acceleration (see Sec-
 tion 4.2.1.3). The following types of information can be
 used to help demonstrate compliance with the seismic
 impact zone management practice:

 • A seismic map, available from State or local agen-
   cies, with the site location marked on the map.

 • Reports from State or local  agencies on earthquake
   activity,  including the  maximum recorded horizontal
   ground level acceleration (as a percentage of the accel-
   eration due to gravity (g),  g=9.8 m/s2) (this information
   is probably contained in any reports on earthquake ac-
   tivity obtained from State or local agencies).

 •  A site inspection that focuses on slopes that may
   have had  the toe removed, water seeps from  the
   base of a slope, less  resistant strata at the base of
   a slope, posts and fences that are not aligned, utility
   poles with sagging or too tight wires, leaning  trees,
   cracks in walls and streets, etc.

•  If the active sewage sludge unit is located in a seismic
   impact zone, documentation on design specifications
  to accommodate the ground motion from earthquakes,
  such as shallower unit side slopes,  more conserva-
  tive design of dikes and runoff controls, and contin-
  gency plans for leachate collection systems.

• Design plans for the  unit indicating the maximum
  ground motion that unit components are designed
  to  withstand,  including foundations,  embankments,
                                                   196

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  leachate collection systems,  liners (if installed), and
  any ancillary equipment that could be damaged from
  seismic shocks.
• Certification by an engineer with seismic design and
  geotechnical experience that the unit is designed to
  withstand the maximum recorded horizontal ground
  level acceleration.

Fault Zones

Part 503 prohibits locating an active sewage sludge unit
within 60 meters of a fault that has had displacement
(i.e., movement) during Holocene time (typically within
the last 11,000 years) (see Section 4.2.1.3). Documen-
tation to support this management practice may-include
the following:
• A Holocene fault  map (available from Jocal .planning
  or State geological agencies or the  USGS) with the
  site location marked. In 1978, the USGS published a
  map series identifying the location of Holocene faults
  in the United States (Preliminary Young Fault Maps
  [USGS, 1978]. For areas along Holocene faults, an
  investigation of the site and surrounding areas should
  be performed to determine if movement has occurred
  since 1978.
• A report on the area investigation of the site, empha-
  sizing the location  of faults, lineaments, or other features
  associated with fault movement, such as offset streams,
  cracked culverts  and foundations, shifted curbs, es-
  carpments, or other linear features.

• A geotechnical report on the site indicating the pres-
  ence or absence of any faults or lineaments.

 Unstable Areas
 Part 503 also prohibits locating active sewage  sludge
 units in unstable areas (see Section 4.2.1.3). The follow-
 ing information  may  be used to demonstrate  that an
 individual active sewage sludge unit is not located in an
 unstable area:
 • A  one-time  detailed geotechnical and geological
   evaluation of the  stability of foundation soils, adjacent
   manmade and natural embankments, and slopes (may
   include both in situ and laboratory test evaluations).

 • A one-time evaluation of the ability of the subsurface
   to support the active sewage sludge unit adequately,
   without damage  to the  structural components. If the
   evaluation indicates that an active sewage sludge unit
   is located in an unstable area, the unit must close.

 Wetlands
 Part 503 prohibits the location of an active  sewage
 sludge unit  in a wetland, unless a  permit is issued
 pursuant to either Section 402 or 404 of the Clean Water
 Act, as amended (see Section  4.2.1.4). The following
types of information may be necessary to demonstrate
compliance with wetland restrictions:

• The location of the site on a wetlands delineation
  map, such as a National Wetlands Inventory map,
  Soil Conservation  Service soil map, or a wetlands
  inventory map prepared locally.

• A permit or permit application for a Section 402 or
  404 permit.

• A description of a wetlands assessment conducted
  by a qualified and experienced, multidisciplinary team,
  including a soil scientist and a botanist or biologist.

Storm Water Runoff

Part 503 requires that runoff jfrqm an active sewage
sludge unit be'collected and dispose'd of*in accordance
with National Pollutant Discharge Elimination System
(NPDES) requirements and any other applicable re-
quirements (see Section 7.2.1.1). In addition, the runoff
collection system must be designed to handle the runoff
from a 24-hour, 25-year storm event. The following types
of information may be used to support compliance with
this management practice:

• Copies of the NPDES  permit and any other permits.

• A description of the design of the system used to
  collect and control runoff, including plan view, draw-
  ing details, cross sections,  and calculations showing
  that the system has the capacity to collect the runoff
  volume anticipated from a 24-hour, 25-year storm
  event.

 • A  calculation  of  peak runoff  flow, including  data
  sources and methods used to calculate the peak run-
   off flow from a 24-hour, 25-year storm  event.

 • A description of inspection and maintenance required
  for the system.

 • A description of the procedures for managing liquid
   discharges and complying  with NPDES and other
   requirements.

 Leachate Collection and Control

 If an active sewage sludge unit has an appropriate liner
 and leachate collection  system,  the owner/operator
 must document that the leachate collection system is
 properly operated and maintained while the unit is active
 and for 3 years after closure  of the sewage sludge unit
 (see Section 7.2.1.2). Documentation must also indicate
 that the leachate is  disposed of properly. The following
 types of information may be used to demonstrate  com-
 pliance with this management practice:

 •  Detailed material specifications for the liner, including
    drainage layer, filter layer,  piping, and sumps.
                                                   197

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 • A description of the leachate collection system de-
   sign, leak detection capability, and capacity for re-
   moval of leachate and liquid from the system.

 • Design details,  including layout of system and com-
   ponents shown in plan view and cross section and
   spacing and configuration of pipes, sumps, pumps,
   drainage plans.

 • Test results demonstrating system compatibility with
   sewage sludge  and leachates for all system compo-
   nents and materials.

 • A description of inspection and maintenance sched-
   ules and procedures.

 • An operational plan describing the method of treatment
   and disposal of  leachate and schedules for disposal.

 • Records of collection, treatment and disposal activities
   that demonstrate compliance with applicable require-
   ments.  For example, volume collected,  monitoring
   data on treated leachate, volume disposed of (where
   and when).

 Monitoring Air for Methane Gas

 Air must be monitored continuously for methane gas
 when an active sewage sludge unit is covered daily
 (see Section 10.4.4). When a final cover is placed on
 a sewage sludge unit,  air must be monitored continu-
 ously for methane gas for 3 years after closure of the
 sewage sludge unit. The following types of information
 may be used to demonstrate compliance with this man-
 agement practice:

 •  A description of  the system design, including plan
   drawing  and calculations  showing that the  system
   can monitor air for methane gas concentrations.

 •  Design details of the site,  including gas monitoring
   locations, spacing, and layout.

 •  Descriptions of air monitoring, alarm systems, emer-
   gency procedures,  emergency contingency plans,
   system  maintenance schedules, and  any  known
   methane gas mitigation.

 •  Results of methane  gas  monitoring,  including the
   maximum and average levels recorded.

 Food/Feed/Fiber Crops Prohibition

 Growing food, feed, or fiber crops on any active sewage
sludge unit is prohibited, unless explicitly authorized by
the permitting authority (see Section 9.2.1.1). The fol-
lowing types of information can be used to demonstrate
compliance with this management practice:

• Approval by the permitting authority if crops are being
  grown on the site.

• A listing of any vegetation on the unit.
 • A description of procedures to ensure adherence to
   the crop use restrictions.

 Grazing Prohibition

 Part 503 prohibits grazing of animals on active sewage
 sludge units, unless specifically authorized by the per-
 mitting authority (see Section  9.2.1.1). The types of
 information that can be used to demonstrate compliance
 with the grazing restriction include the following:

 • Approval by permitting authority if animals are being
   grazed at the site.

 • If the location of the surface disposal site and  the
   land use of surrounding properties exclude or  limit
   grazing, then the only necessary documentation or
   records  may be the certification statement required
   by the regulation that the management practices  are
   being met.

 * If the owner/operator has  to install animal  restriction
   devices  (such as grates at gate entrances  or electric
   fencing), records should be kept on the design, in-
   stallation, and maintenance of the devices  and a site
   map showing the locations of the devices.

 Public Access Restrictions

 Part 503 requires the owner/operator to restrict public
 access to active sewage sludge units and to closed units
 for 3 years after closure (see Section 7.2.1.4). The
 following types of information can be used to demon-
 strate compliance with the public access restrictions:

 •  A site map, showing the access  control  locations
   (e.g.,  placement of signs, fences  and gates, and
   natural barriers).

 •  A description of access restriction measures, such as
   placement of vehicle barriers, signs, and construction
   plans for the placement and configuration  of fences
   and  gates.

 •  Language on warning signs.

 •  An inspection schedule for the  access controls and
   repair procedures.

 •  Schedules for security guard postings or security
   inspections.

 Prohibition of Ground-Water Contamination

 Part 503 states that sewage sludge placed on  an active
sewage sludge unit cannot contaminate an aquifer (see
Section 4.2.1.6).  Compliance with this  management
practice may be demonstrated in either of the following
two ways:

• Certification by a qualified ground-water scientist that
  sewage sludge placed on the active sewage sludge
  unit does not contaminate the aquifer. This should
                                                  198

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  include a report demonstrating that the design, con-
  struction, and operation of the liner/leachate collec-
  tion system or the geology of the site is sufficient
  to retard liquid flow during the active life and post-
  closure period.

• Providing ground-water monitoring data. These data
  should include both baseline monitoring data on the
  aquifer obtained prior to placing sewage sludge in the
  unit, and ground-water monitoring data collected pe-
  riodically throughout the  life of  the  active sewage
  sludge unit.

The regulation requires this management practice to be
met by  either certification of a qualified ground-water
scientist or the results of  a ground-water monitoring
program. The scientist must have  a bachelor or post-
graduate degree in the natural sciences or engineering
and have sufficient training and experience (as demon-
strated by State registration or professional certification)
in ground-water monitoring, pollutant fate and transport,
and corrective actions.

11.2.1.2  Part  503 Recordkeeping Requirements
          for Vector Attraction Reduction

As discussed in Section 3.4.2.3, there are i1 options to
comply with  the vector attraction reduction require-
ments. Options 1 through 8 are performed by the person
who prepares the sewage sludge (see  Section 11.2.3).
Options 9 though  11 are  performed  by the owner/
operator of the surface disposal site. Whenever one of
options 9 through 11 is used, the owner/operator must
certify whether the vector attraction reduction require-
ment is met.  In addition, the owner/operator must keep
records containing a description of how  vector attraction
reduction is met. The description should be supported
by documentation of any activity used to achieve the
vector attraction,reduction.  Records of the certification
and description must be kept for at least 5 years.

 Option 9—Sewage Sludge Injected  Below Surface
 of the Land

 Option 9 requires that the  sewage sludge be injected
 below the surface of the land and that no significant
 amount of sewage sludge  be visible within 1 hour of
 injection. If the sewage sludge meets the Class A patho-
 gen reduction requirements, injection  must take place
 within 8 hours after being discharged from the pathogen
 reduction process. Documentation on compliance could
 include a field notebook with entries  describing how
 sewage sludge is injected below the land surface, the
 class of pathogen reduction achieved, how much time
 elapses between the pathogen reduction process and
 injection (if Class A), and observations on the amount of
 sewage sludge present on the land surface 1 hour after
 sewage sludge was injected.
Option 10—Sewage Sludge Incorporated Into the Soil

If sewage sludge is going to be incorporated into the soil
for vector attraction reduction, the sewage sludge must
be incorporated within  6 hours of placement on the
active sewage sludge unit. If the sewage sludge is Class
A, it has to be placed on the unit within 8 hours after
being discharged from the pathogen reduction process
and then incorporated into the soil within six hours after
placement. There is no  time  period requirement  for
Class B sewage sludge. Documentation on compliance
could include a field notebook with entries describing
how the sewage sludge was incorporated and the class
of pathogen reduction achieved. If the sewage sludge is
Class A, notes should include the date and time (hour
of day) the sewage sludge was discharged from the
pathogen reduction process and the date and  time (hour
of day) the sewage sludge was incorporated into the soil.

Option 11—Sewage Sludge  Covered With Soil or
Suitable Material
Under option  11, the sewage sludge is covered with soil
or other material at the end of each operating day.
Option  11  meets vector attraction reduction require-
ments and pathogen reduction requirements. In con-
trast, when options 9 or 10 are used, either the Class A
or Class B pathogen reduction requirements  have to be
met. Documentation on compliance with option 11 could
include a field notebook describing when and, how the
soil  or another  material is  placed over the sewage
sludge at the end of each operating day, the thickness
of the cover, and the type of cover material used.

11.2.1.3  Records of  Pathogen Reduction

Part 503 does not impose recordkeeping requirements
for pathogen reduction on the site owner/operator.  Be-
cause the  preparer is responsible for pathogen reduc-
tion, the  preparer  must document compliance (see
Section 11.2.3).

 11.2.2  Part 503 Recordkeeping
         Requirements for Owners/Operators
         of Active Sewage Sludge Units
         Without Liners and Leachate
         Collection Systems

 Owners/operators of active sewage sludge units without
 liners and leachate collection systems must comply with
 all of the Part 503 recordkeeping requirements for the
 management practices that encompass design, siting,
 and operation, as well as for vector attraction reduction,
 as described in Section  11.2.1 above. In addition, the
 Part 503 regulation requires owners/operators of active
 sewage sludge units without liners and leachate collec-
 tion systems to maintain records documenting the con-
 centration of pollutants (arsenic, chromium,  and  nickel)
 in the sewage sludge  if the active sewage  sludge unit
                                                  199

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 boundary is less than 150 meters from the property line
 of the surface disposal site or if site-specific pollutants
 have been approved by the permitting authority. Docu-
 mentation of sampling and analysis for pollutant concen-
 trations should include the following information:

 • Date and time of sample collection, sampling loca-
   tion, sample type, sample volume, name of sampler,
   type of sample container, and methods of preserva-
   tion (including cooling).

 • Date and time of sample analysis,  name of analyst,
   and analytical methods used.

 • Laboratory bench sheets indicating all raw data used
   in analyses and calculation of results.

 • Sampling and analytical QA/QC procedures.

 • Analytical results expressed in dry weight.

 11.2.3   Part 503 Recordkeeping
          Requirements for the Preparer of
          Sewage Sludge for Placement on a
          Surface Disposal Site

 The  preparer of sewage sludge placed  on an active
 sewage sludge unit must develop and keep the following
 information for 5 years (U.S. EPA, 1994b):

 •  The concentrations of arsenic, chromium, and nickel
   in sewage sludge for active sewage sludge  disposal
   units with boundaries that are 150  meters  or more
   from the surface disposal site's property line.

 •  A certification statement, as worded in  Figure 11-2.

 •  A description of how certain pathogen and  vector
   attraction reduction requirements are met.

 Table 11-1 outlines a summary of pathogen and vector
 attraction reduction recordkeeping requirements for sur-
 face disposal of sewage sludge (U.S. EPA, 1992).
 11.2.4   Recordkeeping Requirements for
          Surface Disposal of Domestic Septage

 For sites where domestic septage is surface disposed,
 the recordkeeping requirements are dependent on the
 manner in which vector attraction reduction is achieved
 as follows (U.S. EPA, 1994b):

 • If vector attraction reduction is achieved by adjusting
   the pH of  the  domestic septage, the person  who
   placed the domestic septage on the surface disposal
   site must certify to this (see Figure 11-3) and develop
   a description of how vector attraction  reduction was
   achieved. The certification and the description must
   be kept for 5 years.

 OR

 •  If vector attraction reduction is achieved by injecting
   or incorporating the domestic septage into  the  soil,
   or by covering it with soil daily, all management prac-
   tices for surface disposal of sewage sludge must be
   met. Certification that all these  requirements have
   been met and a description of  how they were met
   must be developed and maintained for 5 years. (Fig-
   ure 8-1 in Chapter 8 shows an example of the re-
   quired certification statement.)

 11.2.5  Part 258 Recordkeeping Requirements

 Under Part 258, all documentation and recordkeeping
 requirements are the responsibility of the owner/opera-
 tor of the MSW landfill. A complete discussion  of the
 recordkeeping  and reporting  requirements for MSW
 landfills regulated under Part 258 is beyond the scope
 of this manual. For more information on this subject, the
 reader is referred to U.S. EPA (1993a).

 11.2.6  Other Recordkeeping Requirements

Other federal, state, and  local agencies  may require
specific records to be maintained to comply with permits
or regulations. These include:
                          "I certify, under penalty of law, that the pathogen requirements in [insert
                          ง503.32(a), ง503.32(bX2), ง50332(b)(3), or ง503.32(b)(4) when one of these
                          requirements h met] and the vector attraction reduction requirements in [insert
                          one of the vector attraction reduction requirements in ง503.32(bXl) through
                          ง503.32(b)(8) when one of these requirements is 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 [pathogen
                          requirements and vector attraction reduction requirements if appropriate] have
                          been met. I am aware that there are significant penalties for false certification,
                          including the possibility of fine and imprisonment."
                          Signature
            Date
Figure 11-2.  Certification statement required for recordkeeping: Preparer of sewage sludge placed on surface disposal site (U.S.
                                                   200

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Table 11-1. Certification statement required for
          recordkeeping: Owner/Operator of surface
          disposal site (U.S. EPA, 1994b)

                            Required Records





Who Must Keep
Records?

Description
of How
Class A or B
Pathogen
Requirement
Was Met
Description
of How
Vector
Attraction
Reduction
Requirement
Was Met


Certification
Statement
That the
Requirement
Was Met
 Sewage Sludge—Pathogen Requirements
 Person preparing         •                       •
   trie sewage
   sludge
 Sewage Sludge—Vector Attraction Reduction Requirements
 Person preparing                     •           *
   sewage sludge
   that meets one
   of the
   treatment-related
   vector attraction
   reduction
   requirements
   (Options 1-8)
 Owner/operator of                    •           •
   the surface
   disposal site if a                                 '
   barrier-related
   option (Options
   9-11) is used to
   meet the vector
   attraction
   reduction
   requirement                ?
 Domestic Septige
 Person who places                   •           *"
   domestic
   septage on the
   surface disposal
   site if the
   domestic
   septage meets
   Option 12 for
   vector attraction
   reduction
 Owner/operator of                    •           •
   the surface
   disposal site if a
   barrier-related
   option (Options
   9-11) is used to
   meet the vector
   attraction
   reduction
   requirement
    Water Quality. As part of the monitoring program for
    a discharge permit, such as from a leachate collec-
    tion or treatment system.
    OSHA and/or State Workplace Safety Requirements.
    Information on jobsite safety and safety training and
    education. This includes maintenance of a file of Ma-
    terial Safety Data Sheets for all potentially hazardous
    materials used by employees.
11.3 Cost and Activity Recordkeeping

11.3.1   General

It i& important for the surface disposal site manager to
maintain an  efficient recordkeeping system. Records
must be maintained for administrative use (i.e., payroll,
personnel  management,  purchasing, etc.),  manage-
ment decisions (planning and cost control), as well as
compliance with regulatory requirements (see Section
11.2). The specific records to be maintained will depend
on factors such as the type and size of the site, the
management structure (privately owned, municipal facil-
ity, etc.), the source of operating funds (userfees, sewer
fees, general revenue, etc.), and the requirements of the
regulatory agencies.

 11.3.2   Cost Recordkeeping

A primary concern of a surface disposal site owner/op-
erator is to control costs. Maintaining accurate records
of income and expenditures allows the site manager to
determine unit costs for the site, maintain cost control,
and predict future financial requirements. Costs may be
computed on the basis of time, or units of sludge, such
 as wet tons, dry  tons, or cubic yards.  Based  on this
 information, the income requirements for the site can be
 determined.

 Effective cost control requires timely recognition of ex-
 cessive costs and identification of the reason for such
 cost overruns. The increasing costs and complexities of
 sludge disposal operations require the use of more so-
 phisticated cost control tools than have been used in
 the past.  Use of cost accounting systems at  surface
 disposal sites are recommended for management to
 control costs.
 Because user fees are generally not charged at surface
 disposal sites (reducing the need for accountability) and
 surface disposal sites are not separate enterprises, but
 merely a secondary facet of a larger  operation, cost
 records at many such sites are either nonexistent or
 poorly maintained.

 The installation of a cost accounting system has several
 benefits, as listed below:

 • The system facilitates orderly and efficient accumu-
    lation and transmission of relevant data. Much of the
    recommended data either should be  or  is already
    collected. Hence, the added cost of  installing the
    system is minimal.

 • The data can be grouped in  standard  accounting
    classifications. This simplifies interpretation of results
    and comparison  with data from  previous years or
    other operations.  It also supports analysis of relative
    performance and operational changes.
                                                      201

-------
                            An individual placing domestic septage on a surface disposal site must maintain
                            the following certification statement for 5 years:
                                "I certify, under penalty of law, that the vector attraction reduction
                                requirements in ง503.33(b)(12) 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 vector attraction
                                requirements have been met I am aware that there are significant penalties
                                for false certification, including the possibility of fine and imprisonment." '
                            The owner or operator of the surface disposal site must maintain the following
                            certification statement for 5 years:
                                "I certify, under penally of law, that the management practices in ง503.24
                                and the vector attraction reduction requirements in [insert ง503.33(b)(9)
                                through ง503.33(b)(l 1) when one of those requirements is 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 Co determine
                                that the management practices [and the vector attraction requirements, if
                                appropriate] have been met. I am aware that there are significant penalties
                                for false certification, including the possibility of fine and imprisonment"
                               Signature
                                                                          Date
 Figure 11-3.  Certifications required when domestic septage is placed in a surface disposal site (U.S. EPA, 1994b).
 • The system can account for all relevant costs of con-
   struction and operation.

 • Accumulated data from the system can be used to
   identify which costs are  high and  the  reasons for
   these high  costs. These  data can then be used to
   develop standards of performance and efficiency to
   mitigate inefficient and costly operations.

 • The system includes  automatic provisions for ac-
   countability.  Cost control  becomes  more effective
   when the individual  responsible for cost  increases
   can be  ascertained.

 • Use of the collected data aids in short- and long-term
   forecasting  of capital and operating  budgets. Future
   requirements  for equipment, manpower, cash, etc.,
   can be accurately estimated. This, in turn,  aids plan-
   ning at all levels of management.

 • The system can be flexible enough to meet the man-
   agement requirements associated with different types
   of  surface disposal sites,  different types  of opera-
   tions, and different sludge quantities and types.

 11.3.3  Activity Records

The recordkeeping system should include complete re-
cords of the activity  at a surface disposal site. A daily
report should be completed by the operator on site. This
information can be used by the site manager for billing
purposes,  administrative use, equipment maintenance,
material purchases, and management analysis of the site.

The activity record should include such information as:

• Quantity and type  of sludge received by truckload
 • Cover material utilization

 • Personnel and equipment hours

 • Miscellaneous expenses

 • Sludge placement locations

 Some  of this information may be  available from the
 treatment works, and some or all will be recorded at the
 site. Figure 11-3  is a sample form that could be used to
 record the quantity of sludge received from each incom-
 ing truck on a single day. The daily sludge quantity can
 be totaled at the bottom of the daily form and transferred
 to the  monthly summary included as Figure 11-4. The
 monthly  summary can be used to record the  sludge
 quantity received, as well as cover soil utilization, per-
 sonnel and machine hours, and miscellaneous expenses.

 11.4  Part 503 Reporting Requirements

 77.4.1   General

 In general, the owner/operator of a surface disposal site
 will not be required to report unless specifically notified
 that the site has been designated as a "Class I sludge
 management facility" by the EPA Regional Administrator
 or the  State  Director of an approved  sewage sludge
 management program. If a surface disposal site is des-
 ignated as Class I, the types of information that will need
to be reported will be the same  information as kept for
the recordkeeping requirements. Annual  reports cover
information generated during the calendar year (Janu-
ary 1 through December 31). Owners/operators would
be expected to submit data collected during the course
of the  year. They are  not expected to  resubmit the
                                                     202

-------
                   Site:

                   Month:
                   Completed By:
*

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, ^ ...
'4
i
' rf™
.,, j .
A
— * -
'ifl
p*
rrn
u
TT^
-ft
TT"
,<)
Sludge


















"Jd—
p'J
M
-73T-
M
	 ?r 	
~nr








TgraU





























Covar material




















































































(•mam



























Man
hn.



























Machine
hn.
TIU



























Dawn



























Exat-x
i r/ซ






















































Sir.
hn.



























                    1  ton • 0.907 Hg

Figure 11-4.  Monthly activity form.

one-time documentation  on siting  and design condi-
tions. Annual reports should be submitted to the EPA
Regional Water Compliance Branch Chief. The address
for each Branch  Chief is  provided on the inside of the
back cover of this document. The map on the inside of
the front cover shows the EPA Region in which each
State is located.

In addition, owners/operators who are also preparers of
sewage sludge are required to submit an annual  report
if they are a Class I sludge management facility or if they
are  publicly owned treatment works (POTWs) with  a
design flow rate equal to or greater than 1  million gallons
per  day or POTWs  that serve 10,000 people or more.
Class I sludge management  facilities are defined as
POTWs required to  have a pretreatment program under
40 CFR 403.8(a), including any POTW located in a State
that has elected  to assume local pretreatment program
responsibilities under 40  CFR 403.10(e). The EPA Re-
gional Administrator has  the authority to designate ad-
ditional facilities, including surface disposal sites as
Class I. Preparers include persons who  generate sew-
•age sludge and persons who derive a material from
sewage sludge. Any owner/operator of a surface dis-
posal site who is also a preparer should refer to U.S.
EPA (1993b) for a full  discussion of the preparers'
responsibilities.                   •

11.4.2   Reporting Requirements in the Event
         of Closure

Owner/operators of surface disposal sites that have ac-
tive sewage sludge units that will close are required to
submit a written closure and post-closure plan to the
permitting authority 180  days prior to the closure date.
The plan must include the following elements:

•  Discussion of how the leachate collection system will
   be operated and  maintained for 3  years after the
   sewage sludge unit closes (for units with liners and
   leachate collection systems, only).

• -Description of the system used to continuously moni-
   tor, for 3 years after the unit closes, methane gas in
   the air in any structures within the surface disposal
   site and in the air at the property line of the surface
   disposal site (for units with covers only).
                                                  203

-------
 • Discussion of how public access to the surface dis-
   posal site will be restricted for 3 years after closure of
   the last sewage sludge unit in the surface disposal site.

 In addition, the owner of the surface disposal site must
 provide written notification to the subsequent owner of
 the site that sewage sludge was placed on the land. The
 notification should include:

 • Map of the surface disposal site clearly showing the
   locations of sewage sludge units and their dimensions.

 • Amount  and quality of sewage  sludge placed on
   each unit.

 • Results of methane gas monitoring, if conducted.

 • Type of liner and leachate collection system installed,
   if appropriate, and the volume and characteristics  of
   leachate  collected.

 • Copy of the written closure and post-closure plan.

 • Warnings, as appropriate, that for three years after
   closure air  must be monitored for methane gas if a
   final cover  is placed on any closed sewage sludge
   unit; that leachate has to be collected and disposed
   of properly  if a closed unit has a liner and leachate
   collection system; and, that public access has to be
   restricted.

 11.5  Management Organization

 11.5.1   General

 Surface disposal sites are managed by either public or
 private entities. Public management may be by munici-
 pal or county  government, or by a quasi-governmental
 organization such as a sanitary district.

 11.5.2  Municipal Operation

 Most surface disposal  sites operating today are munici-
 pal operations. In these cases, operation and manage-
 ment  is usually by either the sewer department or the
 department  of public works. Sewer departments often
 manage the disposal site because it is used to dispose
 of the  sludge generated at the department's treatment
 works. Also, because sludge disposal is part  of  the
 overall wastewater treatment process, it is usually sup-
 ported by the  same budget and/or fee structure. Dis-
 posal sites are often located adjacent to the treatment
 works on land  owned by the municipality.

 Management by public works departments is becom-
 ing increasingly common. This arrangement is usually
 more  appropriate for  management of larger sites or
those located some distance from the treatment plant.
Operation of these sites requires construction-type ac-
tivities, making the management requirements  more
 suited to the experience and resources of a public works
 department.

 11.5.3   County Operation

 Management of surface disposal sites by county gov-
 ernments is less prevalent than that by municipal gov-
 ernments.  As with  municipal governments,  county-
 operated sites are often managed by either a sewer
 department or public works department. County sites,
 however, typically serve larger populations  and geo-
 graphic  areas. In these cases the economies of scale
 and greater availability of land for the site favor county-
 operated sites.

 The choice between municipal or county operation is
 usually determined by which government operates the
 sewer department. This should not be the only determin-
 ing factor, however, as county-wide management of sludge
 disposal can be a favorable option even when wastewa-
 ter treatment is conducted by individual municipalities.

 11.5.4  Sanitary District Operation

 Sanitary districts are usually responsible for managing
 surface  disposal  sites when no alternate authority is
 available. Financing for sites managed by sanitary dis-
 tricts is often easier to secure because they usually have
 the power to levy special taxes or user fees. Because
 these districts generally service greater populations and
 may serve several municipal jurisdictions, they often.are
 better  financed and  equipped to operate surface dis-
 posal sites due to the economies of scale.

 11.5.5  Private Operation

 Next to municipal operations, private management is the
 most prevalent type of site management. Sites may be
 operated under contract, franchise, or permit arrange-
 ment.  In contract operations, the  government agency
 contracts with the private  operator to dispose of its
 sludge for a fixed lump sum fee, or a unit charge (per
 ton, cubic yard, ortruckload). If a unit charge is the basis
 of the contractual arrangement, the government agency
 usually guarantees a specified minimum dollar amount
 to the contractor. Franchises typically grant the operator
 permission to dispose of sludge from  specified areas
 and to charge fees that are usually regulated. Permits
 allow the operator to accept sludge for disposal without
 regard  to source.

 Private operations are advantageous for  government
agencies with limited capital available for construction
and initial operation of a disposal site. Private operators
are often able to operate at a lower cost than govern-
ment facilities. Precautions should be taken, however,
to ensure that private operators provide adequate envi-
ronmental safeguards and comply with all regulations.
For this reason, contract arrangements are usually the
                                                 204

-------
most advantageous option for the government because
operating  and performance  standards  can be written
into the contract.

11.6 Staffing and Personnel


11.6.1    General

Staffing requirements for a surface disposal site  de-
pends on  the size and type of the site. Estimates of the
size of the staff required should be developed during the
design process and then refined into a formal staffing
plan for the site. The staffing plan will provide informa-
tion for estimating operating  costs and serve as a guide
for personnel hiring and management.

 11.6.2   Personnel Descriptions

• Equipment operator. At many surface disposal sites,
   equipment operators are the only onsite personnel
   required. Tasks performed are mostly those of equip-
   ment operation. Other tasks, however, may  include
   routine equipment maintenance and directing sludge
   Unloading operations. A sample equipment inspection
   form to be completed daily by equipment operators
   is included as Figure 11-5,
Truck
I dent.
























Totals
Time*

























Sludge
Source?


















Type*








Sludge
Weight
or •
Volume








:









i
1

























      Instructions:  To be completed for each truck, each
                 time it makes a delivery.

      *  Only record time at 15-rainute intervals
      t  Sources:  Code for Contributing Treatment Plant
      +  Types:  G'= grit; DI ป digested; CT =• chemically
              treated
  Figure 11-5.  Dally waste receipt form.
• Superintendent/Foreman/Supervisor.  This  position
  involves overseeing all aspects of the  disposal site
  operation, including maintaining daily records of op-
  eration, personnel supervision, and managing the
  daily activities at the site. Depending on the size of
  the site, this person may serve other functions such
  as equipment operator.
• Mechanic. Major equipment maintenance and repair
  should be performed by qualified mechanics.  Me-
  chanics or maintenance teams, however, are usually
  not needed full-time on the site. They  usually come
  to the site on a  regular schedule or as needed.

• Laborer. Larger surface disposal sites may need one
  or more persons to maintain control systems (e.g.,
  leachate collection and treatment odor control, truck
  washing station, mud and dust  control, etc.). The
  duties may also include maintaining the fencing and
  access roads.
 In addition to the above listed personnel on site, offsite
 support personnel may also be required for efficient
 operation of a surface  disposal site. Such personnel
 may include any of the following:
 •  Clerical. Clerical personnel maintain the records for
  the site, process personnel actions, and perform daily
  administrative duties.
 •  Engineering consultant. A technical consultant should
   be available to advise the site manager on the design
   and operational aspects of the site and its activities.
  The consultant would assist in identifying and solving
   any technical problems that may arise, assisting with
   regulatory compliance issues, and planning and im-
   plementing changes to the site,  such as expansion
   or closure.
 • Management consultant. A management consultant
   can provide assistance on administrative and finan-
   cial issues for the site manager.  The consultant can
   provide advice  on the administration of the site, and
   on financing options for obtaining funds for capital
   and operating expenses.
 • Legal consultant. A legal consultant can provide legal
   services  for, issues such as permitting  and  regulatory
   compliance, public hearings,  contract review, and
   planning for activities such as post-closure use.

 11.6.3  Training and Safety
 It is important to employ well-trained personnel. Quali-
 fied personnel can be the difference between a well-
 organized, efficient operation and a poor operation. New
 employees should not only learn the tasks required for
 their positions, but also understand the purposes and
 importance of the overall disposal operation. Except for
 the larger operations, comprehensive training programs
 are not likely to be designed or conducted by the site
                                                    205

-------
 management. Training programs have been developed
 by the  U.S. Environmental  Protection Agency, profes-
 sional organizations such as the American Public Works
 Association, and some educational associations. Be-
 cause many of the procedures employed  at municipal
 solid waste landfills are similar or identical to those
 employed  at some types of  sludge surface disposal
 sites, such programs may also be useful. Programs may
 consist of guideline information on training activities to
 be conducted by the employer, or classes conducted by
 these agencies.  Equipment  manufacturers are another
 source of information on training procedures.

 Managers of surface disposal sites have an obligation
 to maintain safe and secure working conditions for all
 personnel.  It is important that safety rules are written,
 published, distributed to all employees, and enforced. A
 safety training  program,  covering all  aspects  of site
 safety and  proper equipment operation, as required  by
 OSHA or State safety programs,  should be conducted
 on a regular basis.

 For safety reasons, it is desirable to have two or more
 persons working  on site at any time. This can easily be
 accomplished at  large surface disposal sites  where
 more than one person is needed for daily operation. On
 small sites requiring only one operator, a second person
 should visit the site daily or the single operator should
 phone or check in at the end of the shift.

 At a large site,, a  foreman and  subordinate  supervisors
 may  be required. A multi-shift  operation will require a
 supervisor for each shift as well as an overall manager.
 No matter what the size of the operation, one person
 should be responsible for safety on site, and be familiar
 with OSHA and State regulations and procedures.

 A safety checklist prepared by the  National Solid Waste
 Management association is included as Figure 11-6.
                                                            Site:
                                                            Machine:

                                                            Date:
                                                            Completed By:
                                                            Hour Meter Reading:
                                                             UfOK SUITING CHICK
                                                               WATEK  Q
                                                               INC. OIL D
                                                               IIANS.  Q
                                                               FUEL
                                                               WATEK ADDED FซONT    Q
                                                               ENG.OIl ADDED FIONT  D
                                                               'HANS.on AOOIO now n
                                                               nronAuuCOiiAOOBO   rn
                                                                FIONT           U

                                                            AFTE> STAKING LEVEL MA.;HINI AND CHICK

                                                               ENCINI OIL    Q   __^___
                                                               TUNS.      Q
 WATEป ADDED MM   Q
~ ENO.OIl ADDED MAI  Q
                                                               HYOUIAJC OH  Q
ANV LEAKS
UAKES
STEEIING
TIANSMISSION
MESiLKt
GAUGES
SHIFTING
ENGINE
TEMF.
OIL FtESSUDE
WATEH TEMF.

UNOEHCAUIAGE
HACK ADJUST.
IOILE* WEA*
TIDES
IIADE
CUTTING EDGES
TIUNNIONS
NYDIAUtlCS
FUMF
JACKS
OTHCt
All CLEANIIS
UD. CLEAN
HACK CLEAN
TIDES FUE OF MUD

a
a
a
Cl
C)
G
a
a
C!
Q

C)
C)
Cl
Q
a
o
D
a
D
C
a
n
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D
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a
11.7  References
1
   U.S. EPA. 1994a. Surface disposal of sewage sludge: A guide for
   owners/operators of surface disposal facilities on the monitoring,
   recordkeeping, and reporting requirements of the federal stand-
   ards for the use or disposal of sewage sludge, 40 CFR Part 503.
   EPA/831/B-93/002C. Washington, DC (May).

2. U.S. EPA. 1994b. A plain English guide to the EPA 503 biosolids
   rule, EPA/B32/R-93/003.

3. U.S. EPA. 1993a. Solid waste disposal facility criteria, technical
   manual.  EPA/530/R-93/017 (NTIS PB94-100-450). Washington,
   DC (November).
                                                         Figure 11-6.  Equipment inspection form.
                                                         4. U.S. EPA. 1993b. Preparing sewage sludge for land application or
                                                           surface disposal—A guide for preparers of sewage sludge on the
                                                           monitoring, recordkeeping, 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.

                                                         5. U.S. EPA. 1992. Environmental regulations and technology: Con-
                                                           trol of pathogens and vector attraction in sewage sludge (including
                                                           domestic septage) under 40 CFR Part 503. EPA/625/R-92/013.
                                                           Cincinnati, OH (December).
                                                     206

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BUILDING EXITS (OSHA 1950.35 - 1910.37)






1.
2.
3.
4.
5.
6.
i.ombustt





























1 	
r~






















?.
3.
9.
10.
11.
12.

13.
U.
15.
16.
17.
13.

~~1'9'.
20.

21.
22.
23.
24.
25.
26.-
27.

28.
29.

30.
31.
32.
33.
34.
35.
36.

37.
33.
39.

40".
41.
•42.
43.
44.

45.
46.
47.
48.
49.

Jo.
51.
57
Doors swing with exit travel
Marked with lighted signs
Not locked so that rhey may be used from the inside ot oil times :
Keeo fre* of obstructions
Non-exit doors which coo be mistoken os on axil at on exit or* morked "No Exit*
Singlซ exits or* allowed for rooms containing Its! than 25 people
ble. Oxidizing, ond Flammable Agents, When Using (OSHA 191051 -I9JO. 1 16J
Electrical instollarion and static electricity or* controlled or maintained
Heating appliances at* controlled or maintained in a safe manner
"Hot" work (welding) controlled or maintained in a safe manner
At least one 20 pound Class B fire extinguisher it within 25 feet of a storage area
ICC approved maKsl drums ore used for storage from 5-60 gallons
Not more than required for on* day or shift stored outside storage cabinet
dC)MPflE"SSE& AND LlCtUlftr-O GASES (OSHA 1910.101-1910.116)
Charged ond empty cylinders are separated
Cylinders are grouped by typ* and stored in vertical positions
Cylinders are not stored near other combustible material
Cylinders ore supported so that they eonnof b* tipped over
Cylinder caps are in place on all cylinder) which are not in use
Oxygen cylinders are not stored within 20 feel of other types of gases
DRAINAGE
Drains or* vented to prevent collection of combustible gases
Grease ond oil prevented from entering public 'sewog* systems
ELECTRICAL EQUIPMENT (OsnA I9l0.30o-l$l0.309l
All outlet ond junction boxes are properly covered
All portable electrical tools and appliances are properly grounded
Records maintained for inspection or portable electrical tools ond appliances
Electrical cabinet doors with, exposed conductor! of 50 volts or mor* or* securely fastened
Enclosures around high voltage electrical equipment are marked
Frayed cords, cobles, ond loose wires regularly removed From service
Switch boxes aro identified as to equipment they control
EMERGENCY LIGHTING
Exits and necessary ways to exits are illuminated
Exit signs or* illuminated to at least 5 foot candles
flRE EXTINGUISHER EQUIPMENT (OSHA 1910.157)












Extinguishers are inspected monthly for physical damage
Inspection records are kept indicating inspector
Maintenance performed yearly; hydrotested every 5 years, if required
-Inspection togl marked by month and year ,
Extinguishers conspicuously installed and properly marked for use by type of fir* (A.B.CarD)
The top of portable extinguishers (less than 40 Ibs) mounted no mor* than 5' above the floor
The top of portable extinguishers (40 Ibs or more) mounted no more than 3-1/2' obov* fh* floor
FIRST Alb (OSHA 1916.151)

An approved first aid kit is available
Emergency numbers of company-approved doctors ond hospitals posted in appropriate locations
Trained personnel available
HAND AN& PORTABLE fOOlS (OSHA l9IO.44i-t7IO.247)
Alt useoble tools Hove guards properly installed
All portable electrical tools are tested monthly for ground
Records kept of inspection (item 4f)
All tools in safe operating condition are free from worn or defective parts
Jacks and hoists are legibly marked with the load rating
hOUSEtfEEPlNG
Material on wallvshilves stored m a safe and orderly manner
Facility is in a clean, orderly, ond sanitary condition
Hoses, welding leads, drop lights, *tc. or* rolled ond property stored
Permanent aisles ond passageways ore frป* of obstructions
Permanent aisles and passageways are permanently marked
ILLUMINATION
Sufficient quantity (20 foot candles or greater)
Uniform distribution
W.ll rfirMtod






INDUSTRIAL SANITATION (OSHA 1910. Uli
i
f—
















53.
54.
55.
56.
57.
Clean, available drinking fountains '
Hot water available
Individual towels and drinking cups available
Toilet facilities or* within 200 fee*t of working area for each sex

INDUSTRIAL TRUCK: FORKLIFT (OSHA 1910.178)
58.
59.
60.
61.
62.
63.
64.
65.
66.
Brakes in good' operating condition
Guard behind fork is in place (to guard from load falling to the rear)
Load capacity of truck marked
No one except operator permitted to ride
No one stands or walks under raised Forks
Overhead guard to protect against falling objects
Recharging/refueling don* in o "No Smoking" isolated area
Training program far operators
Warning devices (horn) working

LADDERS (OSHA 1910.25-1910.28)
67.
69.
69.
70.
71.
Anti-slip safety steps used on portable ladders
Caution exercised when metal ladders used in electric current areas
Cautiah exercised when metal ladders used with portable *l*etric tools
Ladders inspected monthly with inspection records kept
Straight ladders properly secured

Figure 11-7.  Safety checklist.
                                                            207

-------
                                                                                         (QihA I9tu.
                                            72.   Bulk  storage (126 to 500 gollons) ot least  10 feet from building
                                            73.   Bulk  stores* (SOI to 2,000 gal lorn) at least  25 feet from building
                                            74.   Bulk  storage (231 to 2,000 gallant) at !ปait  three feet separation between  tanks
                                            75.   Containers labeled by size (in pounds or gallons)
                                            76.   Containers labeled with pressure in "gouge psi"
                                            77.   Containers labeled by type of L.P.G.
                                            78.   Containers havo  safely relief and shut-off valves
                                            79.   Containers stored away from exits
                                            80.   Distance between L.P.G. container! and flammable  liquid container*  it 20 feel
                                            81.   No containers  art stacked on* above the  other
                                            82.   Containers ore stored  in o "No Smoking"  oreo
                                                                    GUARDING  J65HA 1910.21l-l9l0.2Hl
                                            S3.  Abrasive wheels in accordance with  type of work                                  "
                                            34.  Abrasive wheels in good  condition
                                            85,  Abrasive wheels labeled and in accordance with rpm ratings
                                            86.  Abrasive wheels uniform in diameters
                                            67.  Air nozzles used for  cleaning meet 30 osi limit
                                            88.  All rotating, cutting shearing, screw and worm, blending,  and forming motions guarded
                                            89.  Safety precautions understood and used by shop employees
                                            90-  Steady resrs on grinders meet 1/8" adjustment to wheel requirement
                                              PER
        SONAL PROTECTIVE  iQulfrMfNT (05HA  I9lf).ปi,  IปIO. '132-1910707" _
        All protective equipment maintained in safe working condition
        Car protection worn when noise dSA greater than 90 for 8 hours
        Ear protection worn when noise dBA greater than 95 for 4 hours
        Ear orotection worn when noise dBA greater rhon 100 for 2 hours
        Ear protection warn when noise dBA greater thon 105 far I hour
        Ear protection worn when noise dBA greater thon 110 for 1/3! hour
        Ear protection worn when noise diA greater than 1 15 for 1/4 hour
        Eye  end face protection provided where reasonable probability of Injury exists
        Respiratory protective  equipment worn whan air  is contaminated (dust,  gases, etc.)
        Safety shoes, coos, gloves worn when  necessary
                         ปr.i..E -A.I...  i^iA  i..  . — . A' ฑ
                                            92.
                                            93.
                                            94.
                                            95.
                                            96.
                                            97.,
                                            98.
                                            99.
                                           1JC.
                                            	TCSHA 1910.21-1910.24)
                                           101.   Angle of rise  is between 30  to  50  degrees
                                           102.   Fixed stairs  hove at least a 22" width
                                           103.   Fixed stairs  have at least a  1000 Ibs. load strength
                                           104.   Non-ilio treads are present
                                           105.   Stoir railings are 30-34" from top roil surface to forward edgn of step
                                           'Co.   Stairways less  thon  44" wide Tooth  sides enclosed) hove at least one  handrail
                                           1ST.   Stairways less  thon  44" wfde 'one side  open) have at least one stair  raiting on open side
                                           108.   Stairways over  44"  wide (borh sides open) have two  railings
                                           109.   Srcndaro ratlings are 42" nominally  from  top surface of floor
                                           HO.   Wood railing posts at leait 2" x 4" slock spaced not to exceed  6 feet
                                           111.   Pipe  railings ond posts ot least  1-1/2"  nominal  diameter
                                           1)2.   Pipe  roiling  posts spaced not to  exceed 3 feet
                                           113.   Structural steel ratlings =nc Dosrs at least 2" x  2"
                                           114.   Structural steel roiling posts spaced  not to exceed B feet	
                                                                   VENTILATION  (OSHA 1910.94)
                                           MS.   Exhaust  system for removal of toxic fumes ond dust from work  oreo
                                                     WAUING,  WORKING SURFACES  tQSHA J9(6.Jl-.
                                                 Aijiet ond passageways unoeirructed
                                                 Perfnonent walkways  marked
                                                 Floor hole openings guarded and  marked
                                                 Floor surfaces  in good condition ond uncluttered
TToT
 117.
 ltd.
 119.
                                             WELDING, CUTTING,  HeATING OR BRAZING tOSHA  1910.251-1910.254V
                                           120.
                                           121.
                                           122.
                                           123.
                                           124.
                                           125.
       Aceryler* not usซd ar prauor*. greater rhan 15 pug
       Eye protection worn, where required* by exfenf  of hazard
       During welding operations, oaoreciobfe combustibles more than 35 feet  away
       During welding operations, floor iwept clean of combustibles wtrhln 35 fซef
       Fire watch practiced/  where necessary
       Frame of alectn'c welding rr^hine grounded
                                                                               fne grounded
                                                                                SAK.V REQ
                                               	HEAVY EQUIPMENT
                                                 Each piece  of equfpn>ปwif has roll-over protection (iปe Sech'on  X-"Rotl Ovei' Protecrio
                                                 Schedule**)
                                                 Each p-ece  of equipment hoi Fire extinguisher (20 Ibs. ABC Minimum)
                                                 Alt  heavy equipment is  equipped  with  backup alarm
                                                 Alt  machines  operating at night equipped with  headlights
                                                 Seat belt* org on all equipment with roll-over  protection
 127.
 12S.
 129.
 130.
                                                                     MEDICAl AND FJUST AID
                                          132.
                                                Medical oersonnel available tor advice ond  consultation
                                                Suitable oloce to render firsr aid
                                          133.  Adjacent  road  (City, Store,  etc.)  is cleor  of debris and mud
                                          134.  When possible, warning sign or light, "TRUCK  ENTRANCE"
                                          133.  Landfill rood crowned and proper drainage
                                          134.  Landfill rood kept prooerly  cleaned of debris
                                          137.  Landfill rood has proper oust  control by means of a water wagon or water truck
                                          138.  Traffic Control Signs (Landfill) -  Stop sign  (for vehicle leaving landfill before
                                                entering public street)
                                          139.  Traffic Control Signs (Landfill) - Speed limit signs
                                          140.  Traffic Control Signs (Landfill) - No parking signs	
                                                                          LANDFILL  Silt
                                          |4I.  All underground cobles,  Ptpes, etc., are cleorlv marked ono  identified
                                          142.  Utility wires are of sufficient height to allow  clearance for all  equipment using
                                                landfill
                                          143.  Security  fences ond landfill site  is kept free as possible of blowing paper aind debrn)
Figure 11-7.   Safety checklist (continued).
                                                                               208

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                                            Chapter 12
                                Closure and Post-Closure Care
12.1  General

Closure is the procedure through which a surface dis-
posal site is closed after sewage sludge is no longer
placed on the land. Issues to be addressed during clo-
sure include:
• Covering the sludge to  control odors and vectors
  (insects, animals).
• Proper leachate management to prevent contamina-
  tion of ground water or surface water.

• Prevention of methane gas accumulation.

• Maintaining a stable and  secure site throughout the
  post-closure period.
• Selection of and preparation for the final end use of
  the site.

12.2  Regulatory Requirements

 12.2.1  Part 503

The requirements for closure of a surface disposal site
regulated under  Part 503  are specified in Section
503.22. These requirements pertain  to closing active
sewage sludge units in a surface disposal site. Under
these requirements:
•  Closure is required if an active sewage sludge unit
   is located in certain types of areas. If an active sew-
   age sludge unit is located within 60 meters of a fault,
   in an unstable area, or in a  wetland, the unit must
   close by March 22, 1994. There are two exceptions
   to this requirement: (1) if the permitting authority has
   indicated that the location of a specific unit within 60
   meters of a fault is  acceptable, or (2) if a permit was
   issued under the Clean Water Act that allows the unit
   to be located in a wetland (U.S.  EPA, 1994).

 • If an active sewage sludge unit closes, the permitting
   authority must be notified. If an active sewage sludge
   unit  is about to be closed,  the owner/operator of
   the unit must provide the permitting authority with a
   written plan that describes closure and  post-closure
   activities.  At a  minimum, the following information
   must be included in the plan: (1)  how the leachate
  collection system will be operated and maintained for
  3 years after closure (if the unit has such a system);
  (2) a description of the system used to monitor air for
  methane  gas for 3 years after closure  (if the active
  sewage sludge units are covered); and (3) how public
  access will be restricted for 3 years after closure. This
  information must be provided to the permitting author-
  ity 180 days before the unit closes (U.S. EPA, 1994).

The permitting authority may determine that the closure
plan must include provisions for methane gas monitor-
ing or  leachate collection for more than  3 years. For
example, if the sewage sludge placed  in the active
sewage sludge unit was not stabilized, it may be neces-
sary to monitor air for methane gas and restrict access
for a longer period to protect public health. Also, in areas
of high rainfall, the permitting authority may determine
it necessary to collect  leachate for a longer period
to ensure that the integrity of  the liner is maintained
(U.S. EPA,  1994).

Under the general requirements of Part 503:

• Any subsequent landowner must be notified that the
   land  was a surface  disposal site. The owner of a
  surface  disposal site  must  provide  the subsequent
   owner with written notification that sewage sludge
  were placed on the land (U.S. EPA, 1994).

The notification required for the subsequent owner of a
surface disposal site will vary depending on when the
land was sold and the provisions of the closure plan. For
instance, if a surface disposal site was covered, had a
liner, and was sold 1  year after closure, the notification
would inform the next owner that the property was used
to dispose of sewage sludge and that the new owner
must operate the leachate collection system, monitor air
for methane gas, and restrict public access for an addi-
tional 2 years (U.S. EPA, 1994).

 12.2.2  Part 258

The requirements for closure and post-closure care of
a municipal solid  waste (MSW) landfill  are  regulated
under Section 258.60 of Part 258. This regulation also
requires the owner/operator of the MSW landfill to pre-
pare a written closure plan. A complete discussion of the
                                                  209

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 closure requirements under the Part 258 regulation is
 beyond the scope of this manual. The reader is referred
 to U.S. EPA (1993) for additional information on these
 requirements.

 12.3  Closure

 12.3.1  Closure Plan

 The closure  plan is the  document that specifies the
 criteria and procedures to be followed during closure
 and the post-closure period. The closure plan should be
 developed during the site selection and design process,
 because issues that occur at these stages can ultimately
 impact closure and the end use of the site. Also, by
 integrating the final site plans into the preliminary de-
 sign, the ultimate value and cost of developing the final
 site can be enhanced.

 The closure plan  should be reviewed and updated as
 necessary during  the operational life of the facility. The
 objectives of a closure plan include:

 • Designating the design criteria and operational pro-
  cedures for closure.

 • Identifying  operational  and  maintenance  require-
  ments of the post-closure site.
 The contents of a closure plan varies depending on a
 number of factors, such as the type of surface disposal
 site, the regulations controlling the site (i.e., Part 503 or
 Part 258), specific features of the site, the concerns of
 the public, and the requirements  of  the regulating
 authority. The contents  of a closure plan may include:
 • Cover system design
 • Vegetative  cover design

 • Stormwater management controls
 • Inspection and maintenance procedures

 • Leachate management controls
 • Methane gas management controls
 • Other environmental  controls

 • Plans for site access restriction and security

 • Management and recordkeeping  requirements
 • Financial requirements

 Figure 12-1 outlines a sample closure and  postclosure
 plan for an active sewage sludge unit (U.S. EPA, 1994).

 12.3.2 Cover for Monofills or MSW Landfills

The design criteria for landfill closure focus on two cen-
tral themes: (1) the need to establish low-maintenance
cover systems and (2) the need to design a final cover
that minimizes the infiltration of precipitation into  the
waste. Landfill closure technology, design, and mainte-
nance procedures continue to evolve as new geosyn-
thetic  materials become  available,  as performance
requirements become more specific, and as perform-
ance history becomes available for the  relatively small
number of landfills that have been closed using current
procedures and materials. Critical technical issues that
must be faced by the designer include (U.S. EPA, 1993):
            i1   ',,",'",'   ,1  '
• Degree and rate of  postclosure settlement and
  stresses imposed on soil liner components.

• Long-term durability and survivability of cover system.

• Long-term waste decomposition and management of
  landfill leachate  and gases.,

• Environmental performance of the combined bottom
  liner and final cover system.

Much information  has been developed  on final  cover
systems for landfills. The reader is referred to the refer-
ence U.S. EPA (1988) and U.S. EPA (1993) for further
information on landfill cover systems.

12.3.2.1   General

The cover system  is a physical barrier placed over the
sewage sludge unit consisting of layers of soil and
gee-membrane material that isolate the sludge. The de-
sign criteria for a final cover system should be selected
to (U.S. EPA, 1993):

• Minimize infiltration of precipitation into the sludge

• Promote good surface drainage

• Resist erosion

• Restrict gas migration and/or enhance recovery

• Isolate the sludge from vectors

• Improve aesthetics

• Minimize long-term maintenance

Reduction of infiltration in a well-designed final cover
system is achieved through good surface  drainage
"and runoff with minimal erosion, transpiration of water
by plants  in the vegetative cover and root zone, and
restriction of  percolation through  earthen material
(U.S. EPA, 1993).

Each element of a cover system consists of a>layer of
soil or other material selected to meet the requirements
of a specific design criteria. Each element should be
selected and designed based on the requirements of the
specific site and the applicable regulations. The ele-
ments of  a cover  system are the erosion  layer, the
drainage layer, the  infiltration layer, and the gas venting
layer. Figure 7-24 in Chapter 7 illustrates the minimum
requirements for the final cover system (U.S. EPA, 1993).
                                                  210

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Owner/Operator Name:
Mailing Address:
Telephone Number:
Address of Active Sewage
Sludge Unit Location:
     I.      ACTIVE SEWAGE SLUDGE UNIT CONDITIONS

             A.  General information

                 1.   Size of active sewage sludge unit (hectares or acres)
                 2.   Description of liner, if applicable
                 3.   Description of leachate collection system, if applicable
                 4.   Copy of NPDES permit if there are discharges to U.S. waters

             B.  Schedule of final closure (milestone chart)

                 1.   Final date of sewage sludge accepted
                 2.   Date all onsite disposal completed
                 3.   Date final cover completed
                 4.   Final date vegetation planted or other material placed
                 5.   Final date closure completed
                 6.   Total time required to close the site

     H.      DISPOSING OF SEWAGE SLUDGE
             A.  Total volume of sewage sludge to be disposed of on the active sewage sludge
                 unit (m3 or yd3)

             B.  Description of procedures for disposing of sewage sludge

                 1.   Size of surface disposal  site, number of active sewage sludge units, and
                     size of units necessary for disposing of sewage sludge (include site map
                     of disposal area)

                 2.   Design and construction of active sewage sludge units

Figure 12-1.  Outline of sample closure and post-closure plan (U.S. EPA, 1994).
                                             211

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              COVER AND VEGETATION

              A.  Final cover, if applicable

                  1.  Total area to be covered (m2 or yd2)
                  2.  Characteristics  of final cover

                     a.  Type(s) of material(s)
                     b.  Depth of material(s)
                     c.  Total amount of material(s) required

                  3.  Final cover design
                     a.  Slope of cover
                     b.  Length of run of slope
                     c.  Type of drainage and diversion structures

             B.   Vegetation (if vegetation is to be planted)

                  1.  Total area requiring vegetation (hectares or acres)
                  2.  Name or type of vegetation (e.g., rye grass)

             C.   Erosion Control (if vegetation is not to be planted)

                  1.  Procedures and materials for controlling cover erosion
                 2.  Justification  for procedures and materials used

      IV.    GROUND-WATER MONITORING (if applicable)

             A.  Analyses required

                  I.  Number of ground-water samples to be collected
                 2.  Ground-water monitoring schedule (e.g., quarterly, semi-annually)
                 3.  Details of ground-water monitoring program

             B.  Maintenance of ground-water monitoring equipment

      V.     COLLECTION, REMOVAL,  AND TREATMENT OF LEACHATE

             A.  Description of leachate collection system  (i.e.-, pumping  and collecting
                 procedures)

                 1.   Description of the leachate sampling and analysis plan
                 2.   Estimated volume of leachate collected per month

Figure 12-1.  Outline of sample closure and post-closure plan (continued).
                                            212

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            B.   Description of leachate treatment process, if on-site

                     a.  Design objectives
                     b.  Materials and equipment required

            C.   Disposal of leachate

                 1.   If discharged to surface waters, include copy of NPDES permit
                 2.   If hauled offsite, provide final destination

            D.   Maintenance of equipment

                 1.   Repairs and replacements required
                 2.   Regular maintenance required over the duration of closure and  post-
                     closure periods

     VI.    METHANE MONITORING (if applicable)

            A.   Monitoring requirements

                 1.   Monitoring locations
                 2.   Types of samples
                 3.   Number of samples
                 4.   Analytical methods used
                 5.   Frequency of analyses

            B.   Maintenance of monitoring equipment

            C.   Planned responses to exceedances of limits

     VH.   MAINTENANCE ACTIVITIES

            A.   Surface disposal site inspections

                 1.   List all structures, areas, and monitoring systems to be inspected
                 2.   Frequency of inspections for each

            B.   Planned responses to probable occurrences (including those listed below)

                 1.   Loss of containment integrity
                 2.   Severe storm erosion
                 3.   Drainage failure

Figure 12-1.  Outline of sample closure and post-closure plan (continued).
                                             213

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              C.  Maintenance of cover and/or vegetation

                  1.   Cover maintenance activities and schedule
                  2.   Mowing schedule
                  3.   Reseeding and mulching schedule
                  4.   Soil replacement

                      a.  Labor requirements
                      b.  Soil requirements

                  5.   Fertilizing schedule
                  6.   Sprinkling schedule
                  7.   Rodent and insect control program

             D.   Control of erosion

                  1.   Maintenance program for drainage and diversion system
                 2.   Activities required to repair expected erosive damage
                 3.   Replacement cover soil

                      a. Amount to be stored onsite during the post-closure period
                      b. Specification of alternative sources of cover soil, if applicable (i.e.,
                        offsite purchase agreement or onsite excavation)

             INSTALLATION OR MAINTENANCE OF THE FENCE

             A.  If a fence already exists, describe required maintenance at closure to ensure it
                 is in good condition

             B.  If fence is to be installed, specify:

                 1 .   Area to be enclosed
                 2.   Type of materials used,
                 3.   Dimensions of fence

             C.  Security and public access practices planned for the post-closure period

                 1.   Description of security system
                 2.   Maintenance schedule
     IX.    CLOSURE SCHEDULE

            A.   Schedule for closure procedures
            B.   Schedule of periodic inspections
Figure 12-1.  Outline of sample closure and post-closure plan (continued).
                                             214

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12.3.2.2   The Infiltration Layer

The infiltration layer is a low permeability layer consist-
ing of a low permeability soil and/or a geomembrane.
The infiltration layer must be at least 18 inches thick and
composed of earthen material that has a hydraulic con-
ductivity (K) less than or equal to the hydraulic  conduc-
tivity of any bottom liner system or natural subsoils (U.S.
EPA,  1993). The  permeability of the infiltration layer
should be less than or equal to the permeability of any
liner system or natural soils present to prevent a "bath-
tub effect." Figure 12-2 presents an example of a final
cover with a hydraulic conductivity equal to the hydraulic
conductivity of the bottom liner system.

In no case can the final cover have a hydraulic conduc-
tivity greater than 1 x 10"5 cm/sec  regardless of the
permeability of  underlying liners  or natural  subsoils
(U.S. EPA, 1993). If a  synthetic membrane is in the
bottom liner, there must be a flexible membrane liner
(FML) in the final cover to achieve a permeability that is
less than or equal to the permeability of the bottom liner.
Currently, it is  not possible to construct an earthen liner
with a permeability less than or equal to  a synthetic
membrane (U.S. EPA, 1993).

For units  that have a composite liner with  an  FML, or
naturally occurring soils with very low permeability (e.g.,
1 x 10~8 cm/sec), the Agency anticipates that the infiltra-
tion layer  in the final cover will include a synthetic mem-
brane as part of the final cover (U.S. EPA, 1993). A final
cover system  for a landfill  unit with an FML combined
with a soil liner and leachate collection system is pre-
sented in Figure 12-3a. Figure 12-3b shows a final cover
system for a  landfill that has both  a double FML arid
double leachate collection system.

The soil material used for the infiltration layer should be
free of rocks*  clods, debris, cobbles, rubbish and roots
that may increase the hydraulic conductivity by creating

          Erosion Layer
           Min.6"Soil
preferential flow paths. The surface of the compacted
soil should have a slope  between 3 percent and 5
percent after settlement. It is critical that  side slopes,
which are frequently greater than 5 percent be evaluated
for erosion potential (U.S. EPA, 1993).

The infiltration layer should be placed below the maxi-
mum  depth  of frost penetration to avoid  freeze-thaw
effects (U.S. EPA,  1989b). Freeze-thaw  effects may
cause the development of microfractures or realignment
of intersticial fines that can increase the hydraulic con-
ductivity of clays by as much as an order of magnitude.
Infiltration layers may be subject to desiccation depend-
ing  on the climate and soil water retention in the erosion
layer. Fracturing and shrinking of the clay due to water
loss can increase the hydraulic conductivity of the infil-
tration layer (U.S. EPA, 1993). Information regarding the
maximum depth of frost penetration for a particular area
can be obtained from the Soil Conservation Service, local
utilities, construction companies, and local universities.

The infiltration layer is designed and constructed in a
manner similar to that used  for soil  liners, with the
following differences.(U.S. EPA, 1993):

ป The cover is generally not subject to large overburden
  loads, so  the issue of compressive stresses is less
  critical unless post-closure land use will exert large
  loads.

• The soil cover is subject to loadings from settlement
  of underlying materials. The extent  of settlement an-
  ticipated should  be evaluated  and a  post-closure
  maintenance plan designed to compensate for the
  effects of settlement.

• Direct shear tests performed on construction materi-
  als should be conducted at lower shear stresses than
  those used for liner system  designs.
                      Infiltration Layer
                Min. 18" Compacted Soil (1 x 10-6
                         on/sec)
                                                                            2FeetCompaซed
                                                                          SoU (1 x 10-6 cm/sec)
 Figure 12-2.  Example of final cover with hydraulic conductivity (K) < K of liner (U.S. EPA, 1993).
                                                   215

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         Erosion Layer
       To sustain vegetatio;
              Infiltration Layer Mm. 18"
               compacted soil (1 x 10-5
                     on/sec)
                                                                                      FML
                                                                               2 Feet Compacted Soil
                                                                                 (1x10-7 cm/sec)
                                            FML
Figure 12-3a.  Example of final cover design for an MSWLF unit with an FML and leaehate collection system (U.S. EPA, 1993).
           Erotion Layer
         To sustain vegetation
                    Infiltration Layer Min. 18"
                       compacted soil (1 x
                          10-Son/sec)
                                                                                          FML
                                                                               12" Compacted
                                                                             Soil (1x10-7 on/sec)
                          FML
                                             2 Feet Compacted
                                            Soil (1x10-7 cm/sec)
Figure 12-3D.  Example of final cover design for an MSWLF unit with a double FML and leaehate collection system (U.S. EPA, 1993).
Geomembranes
If a geomembrane is used as an infiltration layer, the
geomembrane should be at least 20 mils (0.5 mm) in
thickness, although some geomembrane materials may
need to be a greater thickness (e.g., a minimum thick-
ness of 60 mils is recommended for HOPE because of
the difficulties in making consistent field seams in thin-
ner material) (U.S. EPA, 1993).

12.3.2.3  The Erosion Layer

The erosion layer protects the cover system from ero-
sion due to water and wind. It  also functions  as the
growing medium for the vegetative cover. Selection of
the soil for the erosion layer should consider both its
ability to protect the underlying layers and to support the
vegetative cover. The erosion layer also protects the
infiltration layer from the impacts of freeze thaw cycles.

Soil erosion can reduce the performance of the surface
soil layer of a unit by impairing the vegetative growth or
causing rills that require maintenance and  repair. Ex-
treme erosion may lead to the exposure of the infiltration
layer or the sludge, or may cause slope instability (U.S.
EPA,  1988). Eroded soil can  clog stormwater  drains
resulting  in increased maintenance requirements.

Anticipated erosion due to surface water runoff for a
given design may be approximated  using  the  USDA
Universal Soil Loss Equation (Eq.  12-1)  as shown
below (U.S. EPA, 1989a). By evaluating erosion loss,
                                                   216

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the design may be optimized to reduce damage through
selection of optimum slopes, and best available soil and
plant materials, or by allowing excess soil to increase the
time between required maintenance (U.S. EPA, 1993).

                 , X = RKSLCP          (Eq. 12-1)

where:
   X = Soil loss (tons/acre/year)
   R = Rainfall erosion index
   K = Soil erodibility index
   S = Slope gradient factor
   L = Slope length factor
   C = Crop management factor
   P = Erosion control practice

Values for these parameters are available from the U.S.
Soil Conservation Service (SCS) technical  guidance
document entitled Predicting Rainfall Erosion Losses,
Guidebook 537 (1978), available at local SCS offices
throughout the country.

Figure 12-4 can be used to find the soil loss ratio due to
the slope of the site as used in the Universal Soil Loss
Equation. Loss from wind erosion can be determined by
the following equation (U.S. EPA, 1989a):
                                    A  A
                   X' = I'K'C'L'V
(Eq. 12-2)
where:
  X' = Annual wind erosion
   I' = Field roughness factor
  K' = Soil erodibility index
  C' = Climate factor
  L' = Field length factor
  V = Vegetative cover factor
 12.3.2.4  The Vegetative Cover


The vegetative cover protects the uppermost soil layer
from wind, water and mechanical erosion, and removes
soil water from the site through evapotranspiration. The
vegetative cover is also important because it improves
the appearance of the site.

 In selecting plant species for the vegetative cover, the
following criteria should be considered (U.S. EPA, 1989b):

 •  Plants should be locally adapted  perennials that are
   resistant to drought and temperature extremes.
              ,-.  4
              v\

              3
              2ฃ   1
              |

              I
                                                Slope Length (Feet)
 Figure 12-4.  Soil erosion due to slope (U.S. EPA, 1993).
                                                    217

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• If part of a cover system, the plants should not have
  root systems that will disrupt underlying drainage and
  infiltration layers.
• The plants should be able to thrive in low-nutrient soil
  conditions with minimum nutrient additions.
• There should be sufficient plant density to minimize
  soil cover erosion.

• Plants should  require little or no maintenance.
• Sufficient variety of plant species to continue to achieve
  these characteristics and specifications over time.
Information on suitable species  for a specific site is
available from  the USDA Soil Conservation Service, the
Cooperative Extension Service, or local universities.
Typically, planting or seeding should be conducted in the
fall or early spring to permit seedlings time to become
established  before winter freeze  or summer drought
occurs.  Fast-growing  temporary cover crops such as
winter rye  can provide a  temporary vegetative cover
over winter until conditions for permanent plantings are
favorable (U.S. EPA, 1993).
Surface water runoff should be properly  controlled to
prevent excessive erosion and soil loss. Establishment
of a healthy vegetative layer  is key to protecting the
cover from erosion. However,  consideration also  must
be given to selecting plant species that are not deeply
rooted because they could damage the underlying infil-
tration layer (U.S. EPA, 1993).

12.3.2.5  Alternate Final Cover Design
An alternative  material and/or  an alternative thickness
may be used for an infiltration layer. For example, another
method for controlling  erosion is the use of an armored
surface  as the outer layer of a final cover system. An
armored surface or hardened cap is generally used in
arid regions or on steep slopes where the establishment
and maintenance of vegetation would be difficult (U.S.
EPA, 1993).
An armored surface (comprised of cobble-rich soils or
soils rich in weathered rock fragments) should have the
following characteristics (U.S. EPA, 1989b):
• Capable of remaining in place and minimizing erosion
  of the armored layer and underlying material during
  extreme weather events of rainfall and/or wind.

• Capable of accommodating settlement of the under-
  lying material without compromising the component.
• Designed with a surface slope approximately the
  same as the underlying soil.
• Capable of controlling the rate  of erosion.
Asphalt and concrete may also be used to construct an
armored layer. These  materials,  however, deteriorate
due to thermal expansion and deformation caused by
subsidence. Crushed rock may be spread over the cover
in areas where weather conditions such as wind, heavy
rain, or temperature conditions commonly cause dete-
rioration of vegetative covers (U.S. EPA, 1989b).

On sites subject to Part 258 regulations, armored sur-
faces are considered an alternative final cover design and
may be employed in approved states only and with the
permission of'the'regulating authority (40 CFR 258.60 (b)).

12.3.2.6   Other Components for Final Cover
          Systems

Other components that may be used in the final  cover
system include a drainage layer, a gas vent layer,  and a
biotic barrier layer.  These components are shown in
Figure 12-5.

The Drainage Layer

The drainage layer is a permeable layer constructed
of soil or  geosynthetic drainage material between the
erosion layer and the infiltration  layer. The drainage
layer  conveys water that has percolated through the
erosion layer away from contact with the infiltration
layer, thus reducing the potential  for leachate genera-
tion (U.S.  EPA, 1993).

A typical drainage layer consisting of soil material is at
least 12 in. (30 cm) thick wjth a hydraulic conductivity
between 10"2 and 10~3 cm/sec. The layer should be
sloped between two percent and five percent after set-
tling. The soil material should be no coarser than 3/8 in.
(0.95  cm), classified according to the Universal Soil
Classification System (USCS) as type SP, smooth and
rounded, and free of debris that could damage an un-
derlying geomembrane. Crushed stone is generally not
appropriate because of the sharpness of the particles
(U.S. EPA, 1993).

If geosynthetic materials are used as a drainage layer,
the fully saturated effective transmissivity should be the
equivalent of 1 foot of soil (30 cm)  with  a hydraulic
conductivity range of 10"2 to 10"3 cm/sec. Transmissivity
is calculated as the hydraulic conductivity multiplied by
the drainage layer thickness (U.S. EPA, 1993).

A filter layer composed of a low nutrient soil or a geo-
synthetic material (such as a non-woven needle punch
fabric) should be placed above the drainage layer. The
purpose of this layer is to prevent clogging of the drain-
age layer  by  roots and by the downward migration of
particles with the water.

The Gas Venting Layer

Sites with  impermeable covers must have a system to
collect or disperse the combustible gas (methane) and
other harmful gases (such as hydrogen sulfide) that may
be generated during biodegradation of the sludge. The
                                                  218

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                  60cm
                  30cm
                  30 cm
   20-mil FML—
       or
   60-milllDI'E
60 cm
                             \1//   \l//   \1//
                                                               Vegetation/
                                                               Soil-Top Layer

                                                              . Filler Layer

                                                              > Biulic Barrier Layer

                                                              • Drainage Layer
                                                                   • Low-Permeability
                                                                    FML/Soil Layer
                                                                                 Gas Venting Layer
                                                                                  Waste
Figure 12-5.  Example of alternative final cover design incorporating other components that may be used in final cover systems
           (U.S. EPA, 1993).
gas is collected in the gas vent layer. The gas vent layer
is  usually 12 in. (30 cm) thick and should be located
between the infiltration layer and the sludge. Material
used  in construction of the gas vent layer should be
medium  to coarse-grained porous materials such as
those used in the drainage layer (U.S. EPA; 1993).

A system of horizontal pipes located throughout the gas
vent layer conveys the gases to vertical riser pipes or
lateral headers that penetrate the infiltration layer. If riser
pipes are used, they should be located at high points in
the cross-section. Design of the horizontal pipes should
incorporate some means to drain condensate that will
form in the pipes. If not drained, the condensate can
cause blockage of the pipes at low points. A more de-
tailed discussion concerning  gas at active  sewage
sludge units, including the use of  active and passive
collection systems is provided in Section 7.8.2.

Gas vent pipe penetrations through the cover can cause
problems if settlement occurs. Settlement can  cause
concentrated stresses at  these points damaging the
cover and/or the vent pipes. If a geomembrahe is used
in the cover,  adequate flexibility  and  slack  material
should  be provided at these points. If an active gas
collection system is used, penetrations may be made
through the sides of the cover directly above the liner
anchor trenches where effects of settlement would be
less pronounced (U.S. EPA, 1993).

The Biotic Layer

Deep plant routes or burrowing animals (collectively
called biointruders)  may disrupt the drainage and
the low hydraulic conductivity layers, thereby interfer-
ing with the drainage capability of the layers. A 30-cm
(12-in.) biotic barrier of cobbles directly beneath the
erosion layer may stop the penetration of some deep-
                                   rooted plants and the invasion of burrowing animals.
                                   Most research on biotic barriers has been done in, and
                                   is applicable to arid areas (U.S. EPA, 1993).

                                   12.3.2.7  Other Design Issues

                                   Hydrology

                                   A computer model has been developed to assist design-
                                   ers in evaluating the hydraulic performance of a cover
                                   system. The Hydraulic Evaluation of Landfill Perform-
                                   ance (HELP) Model was developed by the U.S. Army
                                   Corps of Engineers for the EPA. This model is generally
                                   accepted for use in designing landfill cover systems
                                   (U.S. EPA, 1988).

                                   The HELP program calculates daily, average, and peak
                                   estimates of water movement across, into, through, and
                                   out of landfills. Input parameters include soil properties,
                                   climate-logical data, vegetation type,  and site design
                                   data. Output from the model includes precipitation, run-
                                   off, percolation through the base of each cover layer
                                   subprofile, evapotranspiration, and lateral drainage from
                                   each profile. The model  also calculates the maximum
                                   head on the barrier soil layer of each subprofile and the
                                   maximum  and minimum soil moisture content  of the
                                   evaporative zone (U.S. EPA, 1993). (See Section 7.5.7.1
                                   for more information on the HELP Model.)

                                   Settlement

                                   Excessive settlement  and subsidence caused by
                                   decomposition, dewatering  and consolidation of
                                   the sludge can impair the integrity of the cover sys-
                                   tem. Specifically,  settlement  can  contribute to
                                   (U.S. EPA, 1993):

                                   • Ponding of surface water
                                                  219

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•  Disruption of gas collection pipe systems

*  Fracturing of the infiltration layer

•  Failure of geomembranes

Long-term settlement of disposal units should be ana-
lyzed on the basis of the deformation of the waste layers.
Settlement due to deformation of the waste layers is
most likely to occur after closure of the land disposal unit
and final placement of the cover. Therefore, this type of
settlement  has more  potential to cause subsidence
damage to  the  cover than consolidation settlement,
much of which can occur or can be made to occur prior
to closure (U.S. EPA, 1987a).

Settlement can occur within a few days of sludge place-
ment or extend over several years. Experience has indi-
cated that sites may require regrading up to five years after
closure. The rate and extent of settlement are controlled
by several variables including:

•  Sludge characteristics
ซ  Disposal method
•  Soil characteristics

Of these, the characteristics of the sludge  have the
greatest impact Relevant sludge characteristics include:
•  Solids content
•  Volatile solids content
•  Particle size and configuration
Sludge with a low solids content (15 to 20 percent solids)
can be expected to settle more than sludge with a higher
solids content (28 percent solids). Sludge may dewater
due to evaporation, infiltration  (into surrounding soils),
or separation. Dewatering results in an increase in pore
space and loss in volume, and consequent settling.
Sludge with a low solids  content disposed in trenches
can stratify into liquid and solid phases. When this oc-
curs, the solid phase is subject to rapid settlement.

Other factors that influence the stability of the active
sewage sludge unit are the volatile solids content and
the size and  configuration of the sludge  particles.
Sludges with higher volatile solids content will  biode-
grade more and result in  a greater loss of volume and
increased settlement. Sludges  with poorly sorted parti-
cles also settle to a greater extent.

Type of active sewage sludge units influence the poten-
tial for settlement. For example, landfill units in which
the sludge  is bulked with soil  will settle in a different
fashion from monofills.

Area fill disposal  (where  the sludge is not completely
contained)  may experience horizontal  movement or
creeping. Area fill sites are also susceptible to variable
climatic conditions that may affect site stability.
Soil characteristics also affect settlement. The amount
of interim and final cover applied will influence the
degree of settlement by applying  a surcharge to the
sludge enhancing percolation of the liquid into the sur-
rounding soil. The ability of the cover material to bear
weight, inhibit water infiltration,  and hold vegetation  is
important when predicting settlement.

For co-disposal sites, good records regarding the type,
quantity, and location of solid waste materials disposed
will aid in estimating the amount of settlement expected.
Settlement due to consolidation may be minimized by
compacting  the  waste during daily operations of the
landfill or by landffiling baled waste (U.S. EPA, 1993).

If settlement is anticipated, several design options are
possible. For example, the cover thickness can be de-
signed  such that after displacement occurs, surface
drainage is  still  adequate. Figure  12-6  illustrates this
design compensation method (U.S. EPA, 1988).

Slope Stability

Another potential cause of cover failure is displacement
due to slope instability. Slope stability analyses should
be performed to assess the potential for slope failure by
various failure modes (e.g., rotational, sliding, wedge)
as appropriate,  based on the slope configuration.  To
adequately perform  stability analyses, the properties of
the cover system components, the sludge, and the foun-
dation soils must be known as well as seepage condi-
tions  (U.S. EPA, 1988). A discussion of slope stability
can be found in Section 7.5.5.

12.3.3  The Stormwater Management System

Control of stormwater on site is important in the control
of erosion and surface water run-on and run-off. During
closure the site should be graded so there is no ponding
of surface water, and there is no run-on of precipitation
from off-site areas.  Final grades of the site should be
designed so that after any settling has occurred, surface
slopes are between 2 and 5 percent. Drainage pipes and
ditches should convey all stormwater collected away
from the site.

12.4  Post-Closure Maintenance

12.4.1   Inspection Program

A program of regular maintenance is necessary to main-
tain the site  in proper condition during the post-closure
period. The  closure plan should contain an inspection
schedule  and a list of maintenance activities  to be
performed. Records of inspections detailing observations
should be maintained to record and monitor changes in
the site and  its systems. These  records also provide a
continuity of the  inspection process  regardless  of
changes in the personnel conducting the inspections.
                                                  220

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                            5 percent slope
               a. Before Settlement
Potential cracks
                b. After Settlement
             c. Thickenino cover before
               and after settlement
Figure 12-6.  Thickened cover for tolerance of settlement (U.S.
           EPA, 1988).

Table 12-1 contains a list of typical inspection activities
for a surface disposal site.

Site inspections consist of a walkover to  inspect the
systems and appurtenances and to look for evidence of
any developing problems at the site. Aerial photography.
can be useful, especially on larger sites to  identify and
document the extent of any settlement or vegetative
stress. Aerial photography should be used in conjunc-
tion with,  rather than as a. replacement for site walk-
overs. Optical topographic surveys can be used to quan-
tify and record the extent of settlement on the site.

12.4.2  Maintenance

A maintenance program must be developed to ensure
the continued integrity and effectiveness of the cover.
Preventative maintenance work should  be scheduled
periodically  for 2 to 3 years after coyer installation to
prevent loss of vegetation and gully development. Main-
tenance  inspections should be regularly scheduled to
provide early warning of more serious problems devel-
oping that would impact the cover's integrity such as
cover  subsidence, slope failure, leachate or  upward
gas migration, or deterioration  of the drainage  system.
Figure 12-7 provides a brief overview of the elements of
a typical maintenance program (U.S. EPA, 1988). The
references U.S. EPA (1987b) and U.S. EPA (1982) pro-
vide detailed guidance on development of a post-closure
maintenance program.

12.4.2.1   Stormwater  Management System

The stormwater management system  should be in-
spected  to  ensure it has not become blocked  or dam-
aged  by   subsidence.  Drainage  pipes   should be
 inspected and, as necessary, cleaned. Surface drainage
features should be cleared of unwanted vegetation,
 silt, rocks,  and other debris.  Appurtenances  such as
 manholes and  catch basins should be inspected for
 damage and blockage..

 12.4.2.2   Regrading
 Regrading  should be performed  as necessary to main-
 tain the  integrity of the erosion layer. Inspections should
 look for signs of soil erosion  and settlement to be re-
 paired by regrading. Erosion can cause formation of rills
 that, if not  repaired, can lead to exposure of the infiltra-
 tion layer or the sludge. Settlement can cause depres-
 sions and  ponding  of surface  water  or  changes  in
 stormwater flow patterns.

  12.4.2.3   Vegetation
  Regular maintenance of the vegetative cover is impor-
  tant to  promote the  growth of the desired vegetation.
  The vegetation should  be mowed at least twice a year
  to suppress weeds and brush. Fertilizer and pesticides
  should  be  applied as necessary to promote the desired
  growth  and to reduce pest damage.
  The growth of undesirable plants can impair the  vege-
  tative cover. Deep rooted plants can penetrate and dam-
  age underlying drainage and infiltration layers. If such
  plants have  become established, they  should be com-
  pletely  removed and the remaining hole repaired. If the
  roots are  left in place, they can  begin to grow again,
  causing the problem to continue.  Dead roots, as they
                                                  221

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  Tabta 12-1.  Checklist for Surface Disposal Site Inspection
  Cover System                         • Look for formation of rills or other soil erosion damage.
                                       • Look for indications of settlement such as depressions in the surface or ponding of stormwater.
                                       • Look for indications of slope instability on steeper sideslopes.
                                       • Look for signs of leachate outcrops.
                                                                                "',   ,/t ,  ,ป           '  ,                 :
                                       • Check the condition of the vegetation for indications of subsurface problems.
                                       • Note the presence of any invader plant species.
 	 	• Look for any animal burrows.
 Stormwater Management System
Be sure surface drainage features are clear and undamaged.
Be sure catch basins, manholes, and pipes are clean and unblocked.
 Leachate Collection System
Be sure pipes are unblocked and undamaged by settlement.
 Gas Vents
                                         Be sure pipes are unblocked and undamaged by soil movement.
                                         Be sure the infiltration layer is intact and properly sealed around vent pipes.
 Qas Monitoring System
Test the gas monitoring equipment.
 Other Facilities
                                         Inspect roads, buildings, fences, etc., for signs olf wear, damage, or vandalism.
              PREVENTATIV6 MAINTENANCE (2 to 3 years)
              Cover System Component
                  Vegetation

                  Topsoil
                       Frequency
                   twice per year
                   annual
                   as needed
                Task
 mowing (weed and brush)
 fertilization
 soil reconditioning (supplemental
 fertilization, aeration)
             PROBLEM IDENTIFICATION/CORRECTION
             Cover System Component
                  Cover System
                 Run-off Control System
                        Problem
                   gully development
                                                           subsidence
                                                           slope instability
                  gas migration that
                  causes cracking
                  erosion, siltato'on
               Repair
 backfill to original grade with stone of
 narrow size range
 regrade cover
 replant vegetation
 backfill with additional cover soil (care
 should! be taken to maintain continuity
 of low permeable soil layer,
 geomembrarte and drainage layer)
 reconstruct cover
 flatten slopes
 add toa berm  along base of slope
 upgrade or install gas venting system
 install perimeter vents
placement of stone riprap or concrete
modify channel alignment and/or
gradients
Figure 12-7.  Typical elements of maintenance program (U.S. EPA, 1988).
                                                            222

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decay, can provide a preferential pathway for rainwater
through the soil to the underlying layers.
Undesirable vegetation can provide a favorable habitat
for burrowing animals.  If a site inspection  reveals the
presence of animal  burrows, they should be filled with
rocks and soil as a deterrent.

Site inspections should ajso monitor for signs of vege-
tative stress. This can be an indication  of subsurface
problems that are otherwise  undetectable. Unhealthy,
dying or dead plants can be indicators of settlement, or
leachate or gas leakage through the cover or liner.

12.4.2.4   The Leachate Collection System

On all active sewage sludge units that have liners and
leachate collection systems, the leachate collection sys-
tem must be maintained for 3 years during the post-clo-
sure period. Monitoring of the leachate quality should be
conducted  as  required by  permits.  The  permitting
authority might require that ground water and the drain-
age from under the liner must be monitored to ensure
the performance of  the liner system. Under Part 258, if
the owner/operator of an MSW landfill can show that the
 leachate generated  is no longer potentially harmful, per-
 mission may be obtained to cease leachate monitoring.
 The leachate collection system should be checked to
 ensure that  it is functioning properly. The pipes should
 be inspected and cleaned regularly to prevent blockages
 from forming. Leachate outcrops are an indication of a
 rupture in the liner  or the infiltration layer allowing pre-
 cipitation to enter and leachate to escape. Failure of the
 infiltration layer may  be due to settlement, burrowing
 animals, deep-rooted plants,  or severe soil erosion.

 12.4.2.5  Gas Monitoring and Collection System
 Provisions must be made  to monitor the concentration
 of methane gas in  air at the  site for 3 years during  the
 post-closure period. Air must be monitored for methane
 gas in any structure on the site  and at the site property
 line. Concentrations may not exceed 25 percent of the
 Lower Explosive Level (LEL) in air in any structure within
 the property line, and  may not exceed the LEL in air at
 the property line.  For safety  purposes,  it should be
 possible to measure  methane levels within a structure
 without entering it.
 The gas collection system should be inspected to check
 that it is working properly. Vent risers should be checked
to ensure that they are not clogged with foreign matter
such as dirt or rocks. The gas collection pipes should
be flushed and pressure cleaned as necessary. (See
Chapter 10 for additional information on monitoring for
methane gas.)

12.4.2.6   Site Access and Security

Public  access to surface disposal sites  must be re-
stricted for 3 years during the post-closure period. Other
sites may require some security measures to prevent
vandalism to structures, gas vents or other exposed
appurtenances. Traffic control devices may be required
to limit vehicles to areas where they will not damage a
cover system or other features of the site. The closure
plan should describe the security measures to be em-
ployed (fences, traffic barriers, signs, etc.).

Fences, traffic barriers, signs, etc., should be inspected
regularly. Site inspections should look for damage to the
site from vandalism and traffic, authorized or unauthor-
ized. Additional security measures should be added as
necessary. Any  obvious health and safety  hazards
should be remedied  immediately.

 12.5  References
 1. U.S. EPA. 1994. Surface disposal of sewage sludge: A guide for
   owners/operators of surface disposal facilities on the monitoring,
   recordkeeping, and reporting requirements of the federal stand-
   ards for the use or disposal of sewage sludge, 40 CFR Part 503.
   EPA/831 /B-93/002C. Washington, DC (May).
 2. U.S.  EPA. 1993. Solid waste disposal facility'criteria. EPA/530/
   R-93/017.
 3. U.S. EPA. 1989a. Seminar publication: Requirements for hazard-
   ous waste landfill design, construction, and closure. EPA/625/
   4-89/022. Cincinnati, OH.
 4. U.S. EPA. 1989b. Technical guidance document: Final covers on
   hazardous   waste   landfills  and  surface   impoundments.
   EPA/530/SW-89/047. Washington, DC.
 5. U.S. EPA. 1988. Guide to technical resources for the design of
   land disposal facilities. EPA/625/6-88/018. Cincinnati, OH.
 6. U.S. EPA. 1987a. Prediction/mitigation of subsidence damage to
   hazardous waste landfill covers. EPA/600/2-87/025 (NTIS PB87-
   175378).
 7. U.S. EPA. 1987b. Design, construction, and maintenance of cover
   systems for hazardous waste, an engineering guidance document.
   NTIS PB87-191656. Vicksburg, MS: U.S. Army Engineer Water-
   ways Experiment Station (May).
  8. U.S. EPA. 1982. Standardized procedures for planting vegetation
   on completed sanitary landfills. Grant no. CR-807673. Cincinnati,
   OH: Municipal Environmental Research Laboratory (July).
                                                      223

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                                            Chapter 13
                       Costs of Surface Disposal of Sewage Sludge
This section presents typical costs for sewage sludge
hauling, placement in a monofill or dedicated disposal
site, and placement in a municipal solid waste (MSW)
landfill. Costs for waste piles and surface impoundments
are not discussed. Cost curves are presented for sew-
age sludge hauling, monofilling, and dedicated disposal,
and are in terms of cost per wet ton vs. sludge quantity
received. Typical costs are presented for: (1) annualized
site capital costs,  (2) site operating costs, and (3) total
site costs (combined annualized capital and operating).

These curves can be useful in the early stages of sludge
surface disposal site planning. Typical costs should be
used only in preliminary work, however. Actual  costs
vary considerably with specific sludge and site condi-
tions. Therefore,  use of these curves  for computing
specific project costs is not recommended. Site-specific
cost investigations should be made in each case.

13.1  Hauling  Costs

Typical costs for hauling dewatered sewage sludge are
presented in Figure 13-1. As shown, costs are given in
dollars per wet ton as a function of the wet tons of sludge
delivered to the site each day. Costs  are presented for
alternative distances of 5,10,20, 30, 40, and 50 mi (8.0,
 16.1, 32.2, 48.3, 64.4, and 80.4 km) hauls.

 "Principals and Design Criteria for Sewage Sludge Ap-
 plication on Land" (U.S.  EPA, 1978)  and 'Transport of
 Sewage Sludge" (U.S.  EPA,  1976)  were  the primary
 sources of information for data and procedures in devel-
 oping these hauling costs. Other references (U.S. EPA,
 1975; Los Angeles/Orange  County Metropolitan Area,
 1977; Spray Waste, Inc., 1974) are available and also
 were consulted and utilized. Sludge hauling costs were
 originally prepared for the year 1975  but were updated
 to reflect 1994 costs.

 The hauling costs shown in  Figure 13-1 reflect not only
 transportation costs, but also the cost of sludge loading
 and unloading facilities. For a treatment works generat-
 ing wet tons (9.1  Mg) per day of a dewatered sludge and
 a 5-mi (8.0-km) haul, sludge loading  and unloading

 facilities were found to contribute 60 percent of the total
 hauling costs. For a treatment works generating ap-
proximately 250 wet tons (227 Mg) per day of dewatered
sludge and a 40-mi (64.4-km) haul, loading and unload-
ing facilities contributed less than 10 percent of the total
hauling costs.

Because of the differing bases for cost computations,
certain assumptions on sludge volumes and unit costs
were utilized to produce the hauling cost curve. These
assumptions include:

1. The sludge was dewatered and had a solids content
   of approximately 20 percent. It was hauled by a 15
   yd3 (11.5 m3), 3-axle dump truck.

2. Hauling was performed 8 hrs per day, 7 days per week.

3. Overhead and administrative costs were 25 percent
   of the operating cost.

4. Capital costs were annualized. A rate of 7 percent
   over 6 years was used for the trucks with a salvage
   value of 15 percent. A rate of 7 percent over 25 years
   was used for loading and unloading facilities  with no
   salvage value.

 If conditions other than the above-stated conditions pre-
vail  at a  given site, the hauling costs in Figure 13-1
 should be revised upward or downward appropriately.
 As an example, if 10 yd3 (7.6 m3) 2-axle dump trucks
 are used, costs should be higher by factors ranging from
 1.3 for a treatment works generating 250 wet tons (227
 Mg) per day with a 50-mi (80-km) haul, to 1.0 for a plant
 generating 10 wet tons (9.1  Mg) per day  with a 5-mi
 (8.0-km) haul. Alternatively, if a 30 yd3 (23.9 m3) dump
 truck is used, costs should be lower by factors  ranging
 from 0.6 to 1.0 for the aforementioned sludge quantities
 and haul distances.

 13.2 MonofHIs and MSW Landfills

 13.2.1   Site Costs

 Typical, site costs for monofilling sewage  sludges are
 presented in  Figure 13-2, 13-3, and 13-4. As shown,
 costs are given in dollars per wet ton of sewage sludge
 received as a function of the wet ton of sewage sludge
 delivered to the site each day. Costs are presented for
 each  of the alternative monofills regulated under Part
                                                   225

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                                                                               One-way Haul Distance
                                                                              •*•   5-Mile
                                                                              •+•   10-Mile
                                                                                   20-Mile
                                                                                   30-Mile
                                                                                   40-Mile
                                                                                   50-Mile
                       $0
 Figure 13-1.   Typical Costs for Hauling Dewatered Sludge.
                                                             50
                                                       Wet Tons per Day
                  I
                  ฃL
                  I
                       $60
                      $50
                      $40
$30
                      $20
                      $10
                       $0
                                                      Type of MonofiU
                                               •*• Area Pill Layer
                                               •+• Area Fill Mound
                                               *Diked Containment
                                               •B-Narrow Tiench
                                               •*• Wide Trench
                                               •*-Codisposal with Soil
                                               •A-Codisposai with Refuse
                         0
                 100
                                                     200           300
                                                      Wet Tons per Day
Figure 13-2.   Capital Costs for Sludge Monofills and MSW Landfills.
                                                            400
500
                                                        226

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                    $200
                    $150
                I   •
                    $100
                      $50
                       $0
                       TypeofMonofill
                •ป Area Fill Layer
                •+• Area Fill Mound
                *Diked Containment
                •&Narrow Trench
                •* Wide Trench
                •4-Codisposal with Soil
                •A'Codisposal with Refuse
                                      100
200          300
    Wet Tons per Day
                                                                            400
Figure 13-3.   Operating Costs for Sludge Monofills and MSW Landfills.
                      $200
                                                                          Type ofMonofm
                                                                    -* Area Fill Layer
                                                                    •+• Area Fill Mound
                                                                    * Diked Containment
                                                                    •& Narrow Trench
                                                                    ** Wide Trench
                                                                    •4-Codisposal with Soil
                                                                    ACodisposal with Refuse
                                                      200           300
                                                       Wet Tons per Day
 Figure 13-4.   Total Costs for Sludge Monofills and MSW Landfills.
                                                        227

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design dimensions and application rates were devised
for the purposes of these cost calculations. These sce-
narios are summarized in Table 13-1. The cost curve for
each  method was plotted from computations that as-
sumed alternative quantities of 10, 100, and 500 wet
tons per day of sludge for each scenario.

Capital costs are summarized  in Figure 13-2. Capital
cost items included:

1. Land.
2. Site preparation  (clearing  and grubbing, surface
   water control ditches and ponds, monitoring wells,
   soil stockpiles, roads, and facilities).

3. Equipment purchase.
4. Engineering.    •         ...   	  	;     •

Capital costs were then annualized at 7 percent interest
over  5 years (the life of the site) and divided by the
sludge quantity delivered to the site in one year to get
the capital cost per wet ton.
Operating costs are summarized in Figure 13-3. Oper-
ating cost items included:

 1. Labor
2. Equipment fuel, maintenance and parts

 3. Utilities

 4. Laboratory analysis of water samples

 5. Supplies  and  materials

 6.  Miscellaneous and other

 Operating costs  (see Figure 13-3) for one year were
 then divided by the annual sludge quantity delivered to
 the site to get the operating cost per wet ton.

 The  costs shown, which were  derived from a variety of
 published information sources (Equipment Guide Book
 Company, 1977  and 1976; Robert Snow Means Com-
 pany, 1978) and case study investigations, have been
 revised upward to reflect 1994 prices.  Several assump-
 tions were employed  in producing these cost curves.
 These assumptions include:

 1. Life of the surface disposal site was 5 years.

 2. Actual fill  areas  (including  inter-trench  spaces)
    consumed 50 percent of the total surface disposal
    site area.
 3. Engineering was 6 percent of the total capital cost.

  It should be noted that the site costs shown for codis-
  posal operations were derived by dividing the additional
  annualized capital cost and additional operating cost by
  the sludge quantity received. Actual unit costs for typical
  MSW landfills not receiving sludge may be expected to
  be less.
Figure 13-4 shows the total costs for monofills and MSW
units in which sewage sludge is placed.

13.3 Dedicated Disposal of Sewage
      Sludge

Surface disposal on a dedicated surface disposal site
differs from land application programs in that the site is
used primarily or exclusively for the disposal of sewage
sludge. Sludge disposal rates are much higher for dedi-
cated disposal sites than for land application sites. Sew-
age sludge is often placed on a dedicated disposal site
throughout the year, except during inclement weather.

Figures 13-5 through 13-7 present base capital costs,
base annual operating and maintenance costs, and total
costs for sewage sludge  disposed at a dedicated dis-
posal site: The assumptions used in developing these
curves are as follows:

1.  The sludge has a solids content of approximately 5
    percent.

2.  Daily disposal period is 7 hours per day.

3.  Annual disposal period is 200 days per year.

4.  Fraction of land required in addition to disposal area
    is 0.4 of the total surface disposal site.

5.  The disposal rate is 30 to 50 dmt/ha/year.

 13.4 Cost Analysis

 As stated previously, the cost curves in this chapter
 should not be  used for site-specific cost compilations
 performed during design. They can be useful, however,
 in  the preliminary planning stages of a surface disposal
 site. In addition, they are useful in  developing  some
 general conclusions about sludge  surface disposal
 costs. For instance:                  .     .

 1.  Hauling costs ranged from less than $1 per wet ton
    (less than $1 per Mg)  for a 5-mi (8.1-km) haul of 500
    wet tons (453 Mg) per day to $20 per wet ton ($22
    per Mg) for a 50-mi (80.4-km) haul of 10 wet tons
    (9.1 Mg)  per day.

 2. Annualized site capital costs  ranged from $10  per
    wet ton  ($11  per Mg) for a sludge/solid waste
    codisposal  operation receiving 500  wet  tons (453
    Mg) per day to $47 per wet ton ($52 per Mg) for aป
    diked containment operation receiving 10 wet tons
     (9.1 Mg) per day.,

  3. Site operating costs ranged from $5 per wet ton ($6
     per Mg) for a sludge/solid waste codisposal operation
     receiving 500 wet tons (453 Mg) per day to $154 per
     wet  ton ($169  per  Mg)  for an area  fill  mound
     operation receiving 10 wet tons (9.1  Mg) per day.
                                                   229

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                I
                &
                    S2
                    $0
                                                 Wet Tons per Day

Figure 13-5.   Capital Costs for Dedicated Surface Disposal Site.
 4.  Combined site costs ranged from $15 per wet ton
    ($17 per Mg) for a sludge/solid waste  codisposal
    operation receiving 500 wet tons (453 Mg) per day
    to $197 per wet ton ($217 per Mg) for an area fill mound
    operation receiving 10 wet tons (9.1 Mg) per day.

 Also, an assessment can be  made of the relative costs
 of alternative types of sewage sludge units. A prioritized
 list of these methods based on total site costs (see Figures
 13-4 and 13-7) with lowest costs first is as follows:

 1.  Codisposal with sludge/solid waste mixture

 2.  Codisposal with sludge/soil mixture

 3. Wide trench

 4. Dedicated surface disposal site

 5. Narrow trench

 6. Diked containment

7. Area fill layer

8. Area fill mound
                                                      The cost of an active sewage sludge unit is determined
                                                      by the efficiency of the operation in terms of manpower,
                                                      equipment, and land  use. Other factors, such as haul
                                                      distances play a role in the cost effectiveness of a given
                                                      site but are the same  for the various methods.

                                                      As indicated, codisposal and wide trench methods tend
                                                      to be the most economical landfilling methods. Codis-
                                                      posal operations tend to be larger and benefit from the
                                                      economies of scale. In addition, the availability of "free"
                                                      bulking material in the form of solid waste reduces labor
                                                      costs. Wide trenches  have high application  rates and
                                                      are land and labor efficient. It should be noted, however,
                                                      that the relatively high solids content required for effec-
                                                      tive utilization of wide trenches will  increase the cost of
                                                      sludge handling at the treatment plant.

                                                      Narrow trenches have relatively higher labor  require-
                                                      ments and are intensive, contributing to high capital and
                                                      operating costs. Area  fill mounds and layers are labor
                                                      and equipment intensive.

                                                      Diked containment requires a relatively large  operation
                                                      before  it  becomes a cost-effective means of  surface
                                                  230

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                                                                                500
                                                       Wet Tons per Day
Figure 13-6.   O&M Costs for Dedicated Surface Disposal Site.

disposal. This is a result of high initial labor and equip-
ment requirements. Once established, however, diked
containments are efficient in terms of operation and
land use.
13.5 References

1. Equipment Guide Book Company. 1977. Green guide, Vol. I: The
   handbook of new and used construction equipment values.
2. Equipment Guide Book Company. 1976. Rental rate blue book for
   construction equipment.
3. Los Angeles/Orange County Metropolitan Area. 1977. Sludge proc-
   essing and disposal. A state-of-the art review. Regional Wastewa-
'  ter Solids Management Program.                      .
4. Robert Snow Means Company. 1978. Building construction cost
  data ,1978.

5. Spray Waste, Inc. 1974. The agricultural economics of sludge fer-
  tilization. East Bay Municipal Utility District soil enrichment study.
  Davis, CA.

6. U.S. EPA. 1978. Principals and design criteria for sewage sludge
  application on land. Sludge treatment and disposal seminar hand-
  out. U.S. Environmental Protection Agency.
                                                c

7.  U.S. EPA. 1976. Transport of sewage sludge. Contract No. 68-03-
   2168. Cincinnati, OH.

8. U.S. EPA. 1975. Costs of wastewater treatment by land applica-
   tion. Technical report. EPA-430/9-75/003. Washington, DC.
                                                          231

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                       $75
                       $60
                 I
                 I
                  I
                 o
                      $45
                      $30
                      $15
                       $0
                         5                          50                         500
                                                       Wet Tons per Day
Figure 13-7.   Total costs for dedicated surface disposal site.
                                                        232

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                                            Chapter 14
                                        Design Examples
14.1  Introduction
The design of a surface disposal site is dependent on
sludge characteristics and site conditions, such as percent
solids, climate, soil, topography, and others. Consequently,
no design example can be universal. Examples can be
illustrative of the design and operating procedures that
have  been recommended in the preceding chapters,
however.

This chapter contains three design  examples. The ap-
proach in each  of these examples is to present sludge
characteristics and site conditions as given design data.
The first example is for a large monofill  receiving 25
percent solids sludge from a publicly owned treatment
works (POTW) serving  a  population equivalent  of
200,000. In this example, the type of monofill is selected
early in the design process, and the design proceeds to
(1) determine design dimensions, (2) prepare site devel-
opment plans, (3) determine equipment and personnel
requirements, (4) develop operational procedures, and
(5) estimate costs. The second example is for a monofill
receiving 35 percent solids sludge from a POTW serving
a population equivalent of 50,000. In this example, two
alternative monofills appear to be equally suitable at
first.  Alternate  designs are performed for each before
 one monofill is  selected on the basis of costs. The third
 design example is for a small POTW serving a popula-
 tion  equivalent of only 5,000. POTW management is
 faced with a choice between monofilling .their 34 percent
 solids sludge at  the  POTW site or disposing it  at an
 existing MSW landfill.

 It should be noted  that the scope of this chapter is
 confined to design only. Siting and design considera-
 tions for active sewage  sludge units and surface dis-
 posal sites influenced by regulatory requirements are
 discussed in Chapters 4 and  7, respectively.  It should
 also be noted  that the design  described in this chapter
 is somewhat preliminary in nature. A final design should
 contain more detail and address other design considera-
 tions (such as sediment and erosion controls, roads,
 leachate control, etc.), which are not fully addressed
 herein.
14.2 Design Example No. 1

14.2.1  Statement of Problem
The  problem is to design a monofill at a pre-selected
site. The monofill is to receive a 35 percent solids sludge
from a POTW that serves a population equivalent of
200,000. The  recommended design has to be (1) in
compliance with pertinent regulations, (2) environmen-
tally  safe, and  (3) cost-effective.

74.2.2   Design Data
The  following information is the given design data.

14.2.2.1   Treatment Plant Description
The  POTW is a  secondary treatment works. Further
information on the POTW is as follows:
•  Service population equivalent = 200,000
•  Average daily flow rate = 20 MGD (0.86 m3/sec)
•  Industrial inflow rate = 10 percent of total flow rate

•  Wastewater treatment processes:
   - Bar screen separation
   - Aerated grit tanks
   - Primary settling tanks
   - Secondary aeration tanks
   - Secondary settling tanks

 14.2.2.2   Sludge Description
 Sludge is generated primarily  by two sources (primary
 and secondary settling tanks). The sludge is stabilized
 and dewatered. A more complete description is as fol-
 lows:
 • Sludge sources:
   - Primary settling tanks
   - Secondary settling tanks

 • Sludge treatment:
   - Gravity Thickening
   - Mixing
                                                   233

-------
    - Anaerobic digestion
    - Vacuum filtration

  • Sludge characteristics (based on testing, review of
    records, and calculations)
    - Solids content = 25 percent.
    - Quantity on a dry weight basis = 13.0 dry tons/day
      (11.8 Mg/day).
    - Quantity on a wet weight basis = 52.0 wet tons/day
      (47.1 Mg/day).
    - Density = 1,700 Ibs/yd3 (1,009 kg/m3).
    - Quantity on  a wet volume  basis =  61.2 yd3/day
      (46.8m3/day).

 14.2.2.3   Climate

 Significant climatological factors having an impact on
 monofilling are listed below:

 •  Preciptation = 32 in./yr (81  cm/yr).

 •  Evaporation = 28 in./yr (71  cm/yr).

 • Number of days  minimum  temperature 32ฐF (0ฐC)
   and below = 60 days/yr.

 As shown, the climate at the site is relatively mild with
 cold temperatures prevailing approximately two months
 per year. Precipitation exceeds evaporation by 4 in./yr
 (10 cm/yr)

 14.2.2.4   General Site Description

 Preliminary data were collected during the site selection
 process. It is summarized below:

 • Size of property = 375 acre (152 ha)
 • Properly line frontage:
   - 5,200 ft (1,580 m) along country road
   - 4,700 ft (1,430 m) along residences
   - 4,600 ft (1,400 m) along grazing land
   - 1,200 ft (370  m) along woodland

 •  Slopes: Uniform slope of approximately 5 percent
 •  Vegetation:
   - 225 acres (91 ha) of woodland
   - 150 acres (60 ha) of grassland

 •  Surface water None on site

A plan view of the site is presented in Figure 14-1. As
shown, the site has good access along a county road.
The site is located in a moderately developed residential
area and abuts residences. Approximately 60 percent of
the site  is covered with woodland. The balance of the
property is grass-covered.
  14.2.2.5   Hydrogeology

  Eight test borings were performed on the site to deter-
  mine subsurface conditions. These were  located as
  shown in Figure 14-1. Subsurface conditions generally
  are similar at all  boring locations and can be summa-
  rized as follows:

  Depth        Description
.  0-30          Clay

  30-35         Siltysand

  >35          Fractured crystalline rock

  Ground water at the site is at a depth of 30 ft (9.0 m)
  and bedrock is at a depth of 35 ft (10.5 m). Samples of
  the clay were collected for analysis and the following
  determinations made:

  • Texture = fine

  • Permeability = 2x8  cm/sec

  • Permeability class  = very slow

  14.2.3   Design

 14.2.3.1  Selecting  a  Monofill Type

 Table 2-1 in Chapter  2 should be consulted as a refer-
 ence for this section.  The sludge to be disposed at the
 site is stabilized. [Because the  ground slope is relatively
 flat at 5 percent, any  of the monofill types discussed in
 Chapter 2 would  be  suitable  for final disposal of this
 sludge. Because the  sludge has a solids content of 25
 percent, however, only narrow trenches and  area fill
 layers are considered for selection. A  narrow trench
 monofill was ultimately selected because ground water
and bedrock at the site are deep. Cover application, if
appropriate,  would be via land-based equipment  be-
cause of the solids content of the sludge (see Table 2-2
in Chapter 2).  Soil should be  used primarily for cover
and is not required for bulking.

14.2.3.2   Design Dimensions

Table 7-2 in Chapter 7 should  be consulted as  a refer-
ence for this section. As shown in this table, the design
dimensions  to be determined for any trench operation
include the following:

1. Excavation depth
2. Spacing

3. Width

4. Length

5. Orientation

6. Sludge fill depth

7. Cover thickness
                                                  234

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                                                                        0230900780JOOO

                                                                           SCALE M FEET
                                                                                 PREVAILING
                                                                                   WINDS



                                                                                       PASTURE
                                                                                       200
                                                   PASTURE
                      LEGEND

                     -  PROPERTY BOUNDARY

                        ROAD

                        DWELLING


                        WOODS

             ZOO	CONTOURS

Figure 14-1.  Plan view of site in example number 1.
BORING
                                                   235

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 The excavation depth is determined initially by the depth
 to ground water or bedrock.1 A minimum separation of
 2 to 5 ft (0.6 to 1.5 m) is usually provided between sludge
 deposits and the top of bedrock or ground water. In this
 case, a separation of 22 ft (6.6 m) was selected between
 the excavation and ground water. The excavation depth
 will be 8 ft (2.4 m).

 Trench spacing is determined chiefly by sidewall stabil-
 ity. As a general rule,  1.0 to 1.5 ft (0.30 to 0.46 m) of
 spacing provided for every 1 ft (0.3 m) of trench depth.
 Because the soil type is relatively stable, 1.0 ft (0.3 m)
 of spacing for every 1 ft (0.3 m) of trench depth is
 adequate for this site and the total spacing at the site
 will be 8 ft (2.4 m).

 Trench width is determined by sludge solids content and
 equipment considerations. Because the sludge is only
 25 percent solids, a 2- to 3-ft (0.6- to 0.9-m) width should
 be used. At a width of 2 to 3 ft (0.6 to 0.9 m), the cover
 soil creates a bridging  effect over the sludge receiving
 its support from solid ground on either side of the trench.
 A backhoe is the most efficient piece of equipment for
 excavations to an 8-ft (2.4-m) depth. For this site, a 2-ft
 (0.6-m) width is specified based on the equipment effi-
 ciency of the backhoe. The length for narrow trenches
 is limited only by the need to place containment within
 the trench to  prevent low-solids sludge from flowing to
 one end of a trench.  Trench length is set at 200 ft (61
 m). Thus, at every 200 ft (61 m) the trench is discontin-
 ued for 5 ft (1.5 m) to provide containment. With regard
 to trench orientation, trenches should be kept parallel to
 one another to optimize land utilization.  Because of the
 relatively flat  slopes at the site, it is not necessary to
 orient the trenches parallel to topographic contours.
 As shown in Table 7-2, for trench widths between 2 and
 3 ft (0.6 and 0.9 m), the sludge fill depth should be within
 1 to 2 ft (0.3 to  0.6 m) of the ground surface. Because
 the excavation depth  is greater than usual for a trench
 of this width, sludge filling should proceed no closer than
 2 ft (0.6 m) from the top.  Cover application for a 2-ft
 (0.6-m) wide trench should be from 2 to 3 ft (0.6 to 0.9
 m) thick. The chosen cover thickness for this site is 3 ft
 (0.9 m) due to the large sludge fill depth.

 To test the practicality  of these design dimensions, a
 full-scale test was performed at the site. Initially, a back-
 hoe was used to excavate two parallel trenches at the
 previously-specified depth, width, and spacing. A10 yd3
 (7.6 m3) dump truck (to  be used in sludge hauling) was
 then fully loaded with  sludge and backed up to  the
 trench. Because the trench sidewall withstood the load,
 the prescribed trench depth,  width, and spacing were
 found to be sound.  Subsequently, the sludge load was
 dumped into the trench, filling it to a 6-ft (1.8-m) depth.
 About 3 ft (0.9 m) of cover was then gently applied over
 the sludge by the backhoe. The cover was found to be
 adequately supported at this time. At an inspection of
 the test trenches several weeks later, no sludge had
 emerged; however, the cover had settled almost 1 ft (0.3
 m). Because this settlement could cause ponding of
 rainwater over settled trenches in the future, the cover
 application thickness is increased to a total of 4 ft (1.2
 m)  or to 2 ft (0.6. m) above grade. The design can
 proceed based on the following design dimensions:

 • Excavation depth = 8 ft (2.4 m).

 • Spacing  = 8 ft: (2.4 m).

 • Width = 2 ft (0.6 m).

 • Length = 200 ft (61 m).

 • Orientation = trenches parallel to each  other but not
   necessarily parallel to .contours.

 • Sludge fill depth = 6 ft (1.8 m).

 • Cover thickness = ,4 ft (1.2 m).

 14.2.3.3   Site Development

 Site development is in accordance with the plan shown in
 Figure 14-2. Features of this plan included the following:

 • A 300-ft (91-m) wooded buffer is maintained between
   the  sludge fill area and residences. A 200-ft (61-m)
   buffer is maintained around the balance of the property.

 * Trenches are installed along the downhill (southeast-
   ern) property line to collect storm water runoff.2 A
   sedimentation pond is constructed to receive runoff
   collected  by these trenches.

 • In  accordance with  engineering judgment,  one
   ground-water monitoring well is located upgradient
   from the fill area and five monitoring wells are located
   down-gradient from the fill area.

 •  The site  is  divided into nine  active sewage sludge
   units so that the site can be cleared in phases. In this
   way, clearing can  proceed approximately once each
   year in advance of  sludge surface disposal operations.

 •  The active sewage sludge unit located nearest to the
   site entrance is designated for wet weather operations.
   The  access road to this area is paved with asphalt.

 •  The  remaining access roads are covered with gravel.

 •  After providing area for buffers, access  roads, facili-
   ties,  etc., approximately 156 acres (63 ha) remain for
   active sewage sludge units out of the entire 375 acres
   (152 ha) on the site.
1 Th0 Part 503 requirements related to contamination of ground water
are discussed In Chapters 3, 6, and 7.
2 These trenches are designed to have the capacity to handle runoff
from a 24-hour, 25-year storm event in line with Part 503 requirements.
                                                   236

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            -

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          I

            8
         cs
         5*
         •**•
        m
        •VY
                                                                        230  900 750 1000
                                                                         SCALE IN FEET
                                                                              PREVAILING
                                                                                WINDS
                                                              WSTURE
                                                 PASTURE
                   a
 LEGEND

— PROPERTY BOUNDARY
  :ROAD
   DWELLING

   WOODS
	ASPHALT PAVED ACCESS ROAD
• — GRAVEL ACCESS  ROAD
   ) SEDIMENTATION POND
    MONITORING WELL
    SLUDGE FILL AREA
Figure 14-2.  Site development plan for example number 1.
                                                 237

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 14.2.3.4   Calculations

 Based on the design data and dimensions stated pre-
 viously, calculations can be made of the (1) trench utili-
 zation rate, (2) sludge disposal rate, (3) land utilization
 rate, and (4) site life.

 1.  Trench utilization rate
          	sludge volume per day	
            cross-sectional area of sludge in trench  .
          m      sludge volume per day
            (trench fill depth) x (trench width)
            (61.2 yd3/day) x (27 ft3/yd3)
                   (6 ft) x (2 ft)           ,
          - 138 ft/day (41.4  m/day)

 2.  Sludge disposal rate
           cross-sectional area of sludge in trench
                 width of trench + spacing
         _ (6 ft) x (2 ft) _ 12  ft2 __ 12 ft3
         = (2 ft) + (8 ft)   10 ft   10 ft2

             (12 ft3)(1 yd3/27 ft3)
           (10 f1?)(1 acre/43,506 ft2)
         - 1,936 yd3/acre (3,659 m3/ha)

 3.  Land utilization rate
            _ sludge volume per day
              sludge application rate
               61.2 yd3/day
              1,936 yd3/acre
            - 0.0316 acres/0.0128 ha/day)
4. Site life =
                usable fill area
              land utilization rate
                  156 acres       4,937 days
              0.0316 acres/day   365 days/year
            =• 13.5 years


14.2.3.5  Equipment and Personnel

Table 9-4 in Chapter 9 should be consulted as a refer-
ence for this section. As shown, for  a  narrow trench
operation receiving between 50 and 100 wet tons per
day (45 and 91  Mg per day), the following equipment
might be selected:
Description
Track backhoa with loader
Quantity
   1
Hours per Week

     15
Track dozer
Total
                                          30
The use of a backhoe was already established during
the selection  of  design dimensions.  Therefore, the
 above suggested scheme was implemented. The duties
 and number of personnel are also established at this
 stage and include:
 Description                Quantity    Hours per Week
 Backhoe operator               1             40
 Backhoe and dozer operator       1             40
 Total                         2             80

 Operations are conducted at the site 8 hours per day
 and 7 days per week to coincide with sludge deliveries
 and avoid the added cost and odors often encountered
 with sludge storage facilities. The backhoe  is operated
 7 hours per day (plus 1 hour downtime  per day for
 routine maintenance and cleanup) and 7 days per week.
 The dozer is operated 3 hours per day (plus  1 hour
 downtime per day for routine maintenance and cleanup)
 and 5 days per week. One  full-time operator works 8
 hours per day Monday through Friday. He is responsible
 for operating arid maintaining the backhoe during these
 hours.  The  other operator works 8  hours  per day
 Wednesday through Sunday; he is responsible for (1)
 operating and maintaining the backhoe for 8 hours each
 day on Saturday and Sunday, (2) operating and main-
 taining  the dozer  for  4  hours each day  on Monday
 through Friday, and (3) performing miscellaneous func-
 tions such as check station  attendant, compiling site
 records, etc.

 14.2.3.6  Operational Procedures

 Site preparation consisted of the following procedures:

 1. Initially, active sewage sludge  unit  No.  1  and the
   inclement weather area are cleared and grubbed.
   Roads providing access to these areas are paved
   with asphalt or gravel (as shown In Figure 14-2).
   Several trenches are excavated  in the inclement
   weather area and the soil stockpiled alongside each
   trench. Runoff, erosion, and sedimentation controls
   as well as monitoring wells are installed.

2. At least 1  month (but never more than 4 months) in
   advance of the fill operation, each new active sew-
   age  sludge  unit is  cleared  and  grubbed.  Usually
   these operations  occur  once  each year  and are
   timed to avoid cold temperatures and frozen ground
   conditions. The work is performed by equipment and
   personnel brought in specifically for this task. Debris
   is disposed of on-site by burial and/or by producing
   wood chips.

On-going operations consist of the following:

1. Trenching  begins in  the corner of each active sew-
   age  sludge unit furthest removed from  the access
   road and proceeds generally toward the road as it is
   completed.
                                                  238

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   vides contingency capacity for slightly more than one
   day's sludge receipt.

3. Trenches are excavated to design dimensions by the
   track backhoe as it straddles  the excavation (see
   Figure 14-3).

4. Haul vehicles back-up to the previously excavated
   trench  and dump sludge  loads  directly into the
   trench. Filling proceeds to approximately 2 ft (0.6 m)
   below the top of the trench. Because of its low solids
   content, sludge flows evenly throughout the trench
   and accumulations at one location are minimized.

5. Within 1 hour after sludge-filling has  occurred in one
   location, the track backhoe excavates a new trench
   adjacent to the filled trench. Excavated material from
   the new trench is applied as cover over the adjacent
   sludge-filled trench. The cover is applied carefully
   • from a low height at first to minimize the  amount of
   cover sinking into sludge  deposits. Subsequently,
   cover is applied less carefully. Ultimately, the cover
   extends to 2 ft (0.6 m) above grade.

Site completion consists of the following procedures:

1. Approximately 1  month after completion of each 1-
   acre (0.405-ha) portion of an active sewage sludge
   unit, the bulldozer is used to regrade the area to a
   smooth ground surface.

2. Immediately thereafter, the  unit is hydroseeded (as-
   suming weather conditions permit) and grasses soon
   take root.

14.2.3.7  Cost Estimates

Based on the site design, cost estimates were prepared
for capital and operating costs in Tables 14-1 and 14-2,
respectively. As shown, the total capital cost of the site
is estimated at $3,474,945. Considering a site capacity
of 260,000 wet tons (236,000 Mg) of sludge, the capital
cost is $13.31 per wet ton (14.81  per Mg).
                                                Section x-x
 Figure 14-3. Operational procedures for example number 1.
                                                    239

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 Table 14-1.  Estimate of Total Site Capital Costs for Example Number 1
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Runoff Ditch
Pond
Monitoring Wells
Garage
Gravel Roads
Asphalt Roads
Miscellaneous
Equipment
Backhoe
Dozer
Subtotal
Engineering at 6%
Total
Quantity
375 acres

45 acres .
4,000ft
1 ea
6ea
1,600 sq ft
1,500ft
1,000ft


1 ea
1 ea



Unit Cost
$7,500 /acre

$1 ,250 /acre
$5 /ft
$25,000 /ea
$2,000 /ea
$30/sqft
$25 /ft
$42 /ft


$100,000 /ea
$95,000 /ea



Total Cost
$2,812,500

56,250
20,000
25,000
12,000
48,000
37,500
42,000
20,000

100,000
95,000
3,268,250
196,095
3,464,345
Table 14-2. Estimate of Annual Operating Costs for Example Number 1
Item
Labor
Backhoe Operator
Backhoo/Dozor Operator
Equipment Fuel, Maintenance, Parts
Backhoe
Dozer
Clearing and Grubbing
Gravel Roads
Office Trainer Rental
Utilities
Laboratory Analyses
Supplies and Materials
Miscellaneous
Total
Quantity •
2,080 hrs
2,080 hrs
2,555 hrs
780 hrs
10 acres
1,500 ft
1 ea

Unit Cost
$1(i/hr
$1ซ /hr
15.5ei /hr
10.1JI /hr
$1,250 /acre
$25! /ft
$1 0,000 /ea

Total Cost
$37,440
37,440
39,756
7,940
12,500
37,500
10,000
10.000
14,400
20,000
20,000
246,976
As shown in Table 14-2, the annual operating cost is
estimated at $246,976. Considering an annual receipt of
25,000 wet tons (22,700 Mg) of sludge, the unit operat-
ing cost is $9.88 per wet ton ($10.80 per Mg). Combined
capital and operating costs are estimated at $23.25 per
wet ton  ($25.71 per Mg).

14.3 Design Example No. 2

14.3.1   Statement of Problem

The  problem is to design a monofill  at a pre-selected
site. The monofill is to receive a 35 percent solids sludge
from a  proposed  POTW that will  serve a population
equivalent of 50,000. The recommended design has to
be (1) in compliance with pertinent regulations, (2) en-
vironmentally safe, and (3) cost-effective.

14.3.2  Design Data

The following information is the given design data.

14.3.2.1   Treatment Plant Description

The proposed  POTW  is  a secondary treatment work.
Further information on  the POTW is as follows:

• Service  population equivalent = 50,000
                                                 240

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• Average flow = 5.0 MgaVd (0.22 rrrVsec)

• Industrial inflow = 0 percent of total inflow

• Wastewater treatment processes:
  - Bar screen separation
  - Primary clarifier
  - Secondary clarifier
  - Sand filters
  - Chlorine contact tanks

14.3.2.2  Sludge Description

Sludge is to  be generated primarily from two sources
(primary and secondary clarifiers). The sludge  will be
anaerobically digested and dewatered. A more complete
description is as follows:

• Sludge sources:
  - Primary clarifiers
  — Secondary clarifiers

 • Sludge treatment:
  - Gravity thickening
  - Mixing
  - Anaerobic digestion
  - Dewatering via belt presses

 • Sludge characteristics (based on treatment plant de-
   sign report).
   - Solids content = 35 percent.
   - Quantity on a dry weight basis = 3.25 dry tons/day
     (2.95 Mg/day).
   — Quantity on a wet weight basis = 9.3 wet tons/day
     (8.5 Mg/day).
   - Density = 1,750 Ibs/yd3 (1,039  kg/m3).
   — Quantity on a wet volume basis.

   9.3 tons/day x (2,000 Ibs/ton)
             1,750
- = 10.6 yd3/day (8.1 m3/day)
  14.3.2.3  Climate

  Significant climatological factors having an  impact on
  surface disposal are listed below:

  • Precipitation = 48 in./yr (122 cm/yr).

  • Evaporation =  30 in./yr (76 cm/yr).

  • Number of days  minimum  temperature 32ฐF (0ฐC)
    and below = 125  days/yr.

  As shown, the climate is quite cold with freezing tem-
  peratures prevailing during 4 months of the year. Pre-
  cipitation is high  and evaporation exceeds precipitation
  by 18in./yr(46cm/yr).
14.3.2.4   General Site Description
Site data were collected from existing information sources
as well as field investigations performed during the site
selection process. These data are summarized below:

• Size of property = 12 acres

• Property line frontage:
  -  1,750 ft (533 m) along woodland.
  -  500 ft (152  m)  along cropland.
  -  850 ft (259  m) along a county road with woodland
     on the  other side.
• Slopes = relatively flat with  slopes at approximately
  2  percent.

• Vegetation:
  - 6.5 acres (2.6 ha) of woodland.
  - 5.5 acres (2.2 ha) of open space sparsely covered
     with grasses.
•  Surface water =  none on site; drainage on site via
   overland  sheet flow into  roadside ditch.

A plan view of the site is presented in Figure 14-4. As
shown, the  site has good access from a two-lane county
road adjoining the property. Approximately one-half of'
the  site is wooded; the balance is open space with some
grasses. Cropland adjoins the property to the east. Other
adjoining properties are  undeveloped and wooded.

 14.3.2.5  Hydrogeology
 During the  site  selection phase, soil maps for the area
 were reviewed.  In addition, logs of soil borings and wells
 drilled near the site were examined. Historical records
 compiled on nearby drinking water wells were reviewed
 for  ground-water levels and seasonal fluctuations.

 Subsequent to the site selection, four soil borings were
 performed at the site to verify subsurface conditions. These
 borings are located as shown in Figure 14-4. Subsurface
 conditions  were found to be somewhat consistent at all
 boring locations and can be summarized as follows:
                             Depth
                             0-5 ft (0-1.5m)

                             >5ft(>1.5m)
                 Description
                 Coarse sand with silty sand

                 Saturated coarse sand
                             The soil at the site is primarily a coarse sand; however,
                             the sand had some layers of silty  sand interspersed
                             throughout. Ground water is at a depth of 5 ft (1.5 m).
                             Due to the site's location on the coastal plain, bedrock
                             is deep. Samples of the coarse sand were collected for
                             analysis and the following determinations were made.

                             • Texture = coarse

                             • Permeability = 8 x 10"4 cm/sec

                             • Permeability class = moderately rapid
                                                    241

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                                                                               100     ZOO    300
                                                                                       E55"'"
                                                                               SCALE IN FEET



                 LEGEND

                - PROPERTY BOUNDARY
                r COUNTY ROAD
                                                                               CROP LAND
        &&<&ฃ; WOODS
        200       CONTOURS
        S       BORING

Figure 14-4. Site base map for example number 2.
74.3.3  Design

14.3.3.1   Selecting a Monofill Type
Table 2-1 in Chapter 2 should be consulted as a refer-
ence for this section. Because the sludge is stabilized
and has a solids content of 35 percent, this sludge can
be disposed in any of the types of monofill described in
Table 2-1. None of these monofills are disqualified on
the basis of sloping  requirements, because the site is
relatively flat (2 percent slopes).
Because the site is relatively small and a longer site life
is desired, it becomes obvious early in the design proc-
ess that a high sludge disposal  rate is required. As
shown in Table 2-2 in Chapter 2, the highest sludge
disposal rates are attained with wide trenches, area fill
mounds, and diked containments. Diked containment is
ruled  out because the high disposal rates sometimes
achieved with this type of monofill are only possible for
large  diked  containments (with high dikes) receiving
large  quantities of sludge. Wide trenches are initially
selected based on the cost-effectiveness of this opera-
tion versus  area fill mounds.  Normally a  5-ft (1.5-m)
depth to ground water is sufficient to allow trench exca-
vation and still provide sufficient buffer soils. The soil's
coarse texture and moderately rapid permeability at this
site, however, indicated a strong potential for contami-
nant movement without a liner. Therefore, subsurface
                                                  242

-------
placement of sludge in wide trenches lined with recom-
pacted clay and gee-membranes is one proposed mon-
ofilltype.

Surface disposal of sludge in area fill mounds is retained
as a possible disposal option even though area fill
mounds have disadvantages in high precipitation areas
such as at this site.

14.3.3.2  Design Dimensions

Preliminary designs are performed for each type of mon-
ofill still under consideration. The purpose of these de-
signs is to provide a basis for the  site life and cost for
each method in order to select the best disposal method.
Using Tables 7-2  and 7-4 in Chapter 7, dimensions are
computed for each method as shown in Table 14-3.

14.3.3.3  Site Development

Site development is planned in accordance with Figures
14-5 and 14-6 for wide trench  and area fill mound op-
erations, respectively. Features included in both plans
are as follows:

1. A buffer is maintained to all adjoining property. Where
   wooded areas exist along property  frontages, a
   100-ft (30-m)  wide strip is maintained in its natural
   state. Where  grassy open space  areas exist along
   property frontages, a 150-ft (46-m) wide strip is un-
   disturbed.

2. A sodded diversion ditch is included along the uphill
   side of the site to intercept upland drainage. Intercepted
    runoff is directed to existing roadside ditches.3
     dimensions of these drainage devices are checked to ensure
 they have the capacity to handle runoff from a 24-hour, 25-year storm
 event in line with Part 503 requirements.
3. A sodded collection ditch was included along the down-
   hill side of the site to intercept on-site drainage. Inter-
   cepted runoff was directed to a new sedimentation pond.

Features specific to the wide trench operation shown in
Figure 14-4 included the following:

1. Trenches are laid out in accordance with  design
   dimensions and make optimal use of available land.

2. Gravel roads are constructed as shown to provide
   access from the site entrance to individual trenches.

3. A liner system is installed including 2 ft of recompacted
   clay of 1 x 10'7 cm/sec permeability, plus 60 mil HOPE
   geomembrane  along the bottom and  sideslopes.  A
   leachate collection  system is installed on the floor
   above this.                          ;

Features specific to the area fill mound operation shown
in Figure 14-5 included the following:

1. An asphalt-paved dumping/mixing pad and  access
   road is specified.

2. A  soil stockpile area is located near the dumping/
   mixing pad. Soil for this stockpile is imported  once
   each year from another location incurring a 3-mile haul.

3. Most of the  remaining  site area is designated for
   surface disposal operations.

14.3.3.4   Calculations

Based on the design data and dimensions stated pre-
viously, calculations are performed for each of the pro-
posed monofill types. Determinations made on the wide
trench application include:

• Trench capacity = 1,481 yd3/trench (1,132 m3/trench).

• Number of trenches = 12

 • Site capacity = 17,772 yd3/trench (13,588 m3)
 Table 14-3.  Design Considerations for Example Number 2
Design Consideration
Width
Depth
Length
Spacing
Bulking Performed
Bulking Agent
Bulking Ratio
Sludge Depth Per Lift
Number of Lifts
Cover Applied
Location of Equipment
Interim Cover Thickness
Final Cover Thickness
Imported Soil Required
Wide Trench
50ft
8ft
200ft
20ft
No
— —
— .—
4ft
1
Yes
Sludge-Based
—
4ft
No
Area Fill Mound
	 	
—
—
—
Yes
Soil
1 Soil : 1 Sludge
6ft
1
Yes
Sludge-Based
—
3ft
Yes
                                                    :243

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                                                                              100    tOO    3OO
                                                                             9__sae=
                                                                              •CALK IN FEET

                                                                                  CROP LAND

                                                                                C.OP
                     LEGEND
                	PROPERTY BOUNDARY
                	COUNTY ROAD
                   R WOODS
                      ASPHALT PAVEMENT
 K\N MOUND  AREA
	*-DIVERSION DITCH
       COLLECTION DITCH
       SEDIMENTATION POND
Figure 14-5. Site development plan for example number 2 area fill mound.
• Sludge volume received = 10.6 yd3/day (8.1 m3/day)
• Site life = 4.6 years
Determinations made on the area fill mound-application
include:
• Sludge application rate = 9,680 yd3/acre (18,295 rrvVha)
• Size of mounding area = 3 acres (1.22 ha)
• Site capacity = 29,040 yd3 (22,204 m3)
• Sludge volume received = 10.6 yd3/day (8.1 rrvVday)
• Site life = 7.5 years
14.3.3.5   Equipment and Personnel
Using Table 9-4 in Chapter 9 as a reference, the follow-
ing equipment and  personnel were selected for use at
the wide trench operation:
            Description
            Track Dozer
            Track Dozer Operator
Quantity
   1
   1
Hours per Week
     10
     10
           The following equipment and personnel were selected
           for use at the area fill mound operation:
           Description                 Quantity     Hours per Week
           Track Loader                   1             15
           Track Loader Operator       •     1             20

           14.3.3.6  Cost Estimates

           Cost estimates were computed for each of the proposed
           monofill types. These estimates have been included as
           Tables 14-4 through 14-7. As shown, the annual opera-
           tion cost of the wide trench operations is calculated at
           $55,334. The capital cost is calculated at $511,573.
                                                   244

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                                                                                        900
                                                                              CROP LAND
                     LEGEND

            	PROPERTY BOUNDARY
                   • COUNTY ROAD
                   * WOODS
TRENCH

DIVERSION DITCH

COLLECTION DITCH

SEDIMENTATION POND
            	GRAVEL  ROAD

Figure 14-6.  Site development plan for example number 2 wide fill trench.
The  annual operating cost of the area fill mound is
calculated at $70,570. The total capital cost is calculated
at $514,276. Unit costs for each monofill are summa-
rized below:
Wide Trench
Area Fill
Mound
14.3.3.7   Conclusion

An area fill mound is selected and utilized. Although the
area fill mound actually costs more than the wide trench,
the cost difference is not that substantial and the area
fill mound's longer life makes it the clear-cut choice for
the surface disposal site.
Capital Cost
$36.94/wet ton
($40.74/Mg)
$27.40/wet ton
($29.42/Mg)
Operating
Cost
$13.54/wet ton
($14.93/Mg)
$26.92/wet ton
($29.03/Mg)
Total Cost
$50.48/wet ton
($55.67/Mg)
$52.72/wet ton
($58.14/Mg)
     14.4  Design Example No. 3

     14.4.1  Statement of Problem

     The problem is to  design  a  monofill on the site of a
     POTW serving a population  equivalent of 5,000. The
     POTW had been disposing of their 34 percent solids
     sludge at an MSW landfill 8 miles (13 km) distant; how-
     ever, landfill operators now are charging $60.00 per wet
     ton ($66.15 per Mg) for the sludge. Therefore, POTW
     operators are seeking the cost-savings that might be
     realized by surface disposal of the sludge themselves.
     The recommended design  has to be (1) in compliance
     with pertinent regulations, (2) environmentally safe, and
     (3) cost-effective.

     14.4.2  Design Data

     The following information is the given design data.
                                                  245

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Table 14-4.  Estimate of Total Site Capital Costs for Example Number 2 Wide Trench
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Recompacted Clay Liner
Geomembrane
Leachate Collection
Monitoring Wells
Gravel Roads
Miscellaneous
Equipment
Track Dozer
Subtotal
Engineering at 6%
Total
Quantity
12 acres

6 acres
1,750ft
850ft
1 ea
9,680 cu yd
130,680 sqft
9,680 cu yd
Sea
950ft


1 ea



Unit Cost
$7,500 /acre

$1,250 /acre
$5 /ft
$5 /ft
$10.000/63
$7 /cu yd
$0.45 /sq ft
$10/cuyd
$2,000 /ea
$25 /ft


$95,000 /ea



Total Cost
$90,000

7.500
8,750
4,250
10,000
67,760
58,806
96,800
10,000
23,750
10,000

95,000
482,616
28.957
J
511,573
Table 14-5. Estimate of Annual Operating Costs for Example Number 2 Wide Trench
Item
Labor
Dozer Operator
Equipment Fuel, Maintenance, Parts
Track Dozer
Leachate Management
Laboratory Analyses
Other Supplies and Materials
Miscellaneous
Total
Quantity
780 hrs
520 hrs
20,000 gallons

Unit Cost
$18 /hr
10.1 8 /hr
$0.20 /gallon

Total Cost
$14,040
5,294
4,000
12,000
10,000
10,000
55,334
14.4.2.1   Treatment Plant Description
The POTW is a package plant. Further information on
the POTW is as follows:
• Service population equivalent = 5,000
• Average flow = 0.5 Mgal/d (0.022 m3/sec)
• Industrial inflow = 0 percent of total inflow
• Wastewater treatment processes:
  — Bar screen  separation
  - Primary clarifier
  — Aeration tanks
  — Secondary clarifier
14.4.2.2   Sludge Description
Sludge from the secondary clarifier is recirculated to the
primary clarifier. The sludge is stabilized and dewatered.
A more complete description is as follows:
• Sludge sources—sludge from secondary clarifier re-
  circulated to primary clarifier and withdrawn as mix-
  ture with primary sludge.
• Sludge treatment:
  - Aerobic digestion
  - Dewatering  via sand drying beds
• Sludge characteristics (based on testing,  review of
  records, and calculations).
  - Solids content = 34 percent.
                                                   246

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Table 14-6. Estimate of Total Site Capital Costs for Example Number 2 Area Fill Mound
Item
Land
Site Preparation
Clearing and Grubbing
Sodded Division Ditch
Sodded Collection Ditch
Pond
Recompacted Clay Liner
Geomembrane
Leachate Collection
Monitoring Wells
Asphalt Paving
Miscellaneous
Equipment
Track Dozer
Subtotal
Engineering at 6%
Total
Quantity
12 acres

6 acres
1,750ft
850ft
1 ea
9,680 cu yd
1 30,680 sq ft
9,680 cu yd
Sea
4,200 sq ft


1 ea



Unit Cost
$7,500 /acre

$1,250 /acre
$5 /ft
$5 /ft
$1 0,000 /ea
$7 /cu yd
$0.45 /sq ft
$10/cuyd
$2,000 /ea
$2 /sq ft


$120,000 /ea



Total Cost
$90,000

7,500
8,750
4,250
10,000
67,760
58,806
96,800
10,000
6,300
5,000

120,000
485,166
29,110
514,276
 Table 14-7.  Estimate of Annual Operating Costs for Example Number 2 Area Fill Mound
Item
Labor
Loader Operators
Equipment Fuel, Maintenance, Parts
Track Dozer
Leachate Management
Laboratory Analyses
Other Supplies and Materials
Miscellaneous
Total
Quantity
1,040 hrs
780 hrs
20,000 gallons

Unit Cost
$18 /hr
20.32 /hr
$0.20 /gallon

Total Cost
$18.720
15,850
4,000
12,000
10,000
10,000
70,570
   - Quantity on a dry weight basis = 0.33 dry tons/day
     (0.30 Mg/day).
   - Quantity on a wet weight basis = 0.96 wet tons/day
     (0.87 Mg/day).
   - Density- 1,850 Ibs/yd3/day (1,098 kg/m3).
   — Quantity on a  wet volume  basis  = 1.03 yd3/day
     (0.79 m3/day).

 14.4.2.3  Climate

 Significant climatological factors having an impact on
 surface disposal are listed below:

 • Precipitation = 32 in./yr (81.3 cm/yr).
• Evaporation = 34 in./yr (86.4 cm/yr).
• Number  of days minimum temperature 32ฐF (0ฐC)
  and below = 40 days/yr.
The climate of the site is marked by mild temperatures.
Precipitation is moderate and is exceeded slightly by
evaporation.

14.4.2.4  General Site Description

The area to be used for a surface disposal site occupies
a 3-acre (1.2-ha) portion of the 8-acre (3.2-ha) treatment
plant property. It is located immediately adjacent to the
POTW's sand drying beds. Other data concerning this
3-acre tract is summarized below:
                                                    247

-------
 • Adjoining properties:
   — 700 ft (210 m) abuts woodland which is privately
     owned.
   - 700 ft (210 m) abuts POTW.

 • Slopes = evenly sloped at about 6 percent.

 • Vegetation = all 3 acres (1.2 ha) had been previously
   cleared and are covered with grasses.

 • Surface water = none of the 3-acre (1.2 ha) tract. A
   stream which receives effluent from the treatment
   facility is located 500 ft (150 m) away.

 14.4.2.5  Hydrogeology

 Site hydrogeological data  was collected  largely from
 information contained in the POTW report and drawings.
 Some additional information  on  soils,  bedrock,  and
 ground water was obtained from  the sources listed in
 Chapter 6.

 Subsurface conditions are summarized as follows:
Depth
0-10 ft (0-3.0 m)

10-12 ft (3.0-3.7 m)

12-15 ft (3.7-4.6 m)
15-26 ft (4.6-7.9 m)

>26 ft (7.9 m)
Description

Silly clay with some clay lenses
Interspersed throughout

Saturated silty clay
Clay

Saturated silty clay
Bedrock
The upper 10 ft (3.0-m) of soil was a dry silty clay and
ground water was encountered at 10 ft (3.0 m). A 3-ft
(0.9-m) thick tight clay seam protects the ground water
located below it. Using Table 4-2 and Figures 4-8 and
4-9, the following determinations were made:

• Texture = fine

• Permeability = approximately 1 x 10"7 cm/sec

• Permeability class = very slow

14.4.3  Design

14.4.3.1   Selecting a Monofill Type

This site is conducive to subsurface placement of sludge
because ground water and  bedrock are relatively deep
(at  10 and 26 ft [3.0 and 7.9 m], respectively), and the
soils are tight enough to afford sufficient environmental
protection. Because area fills are generally more man-
power and equipment-intensive then  are  trenches,
trenches should be selected  in  almost all  instances
where hydrogeologic conditions allow. In addition, wide
trenches should be selected over narrow trenches for
sludge with a solids content of 34 percent.  An active
sewage sludge unit liner is desirable  (geomembrane
only). Cover application, if  appropriate, should  be via
sludge-based equipment. All of these considerations
were established and utilized in the preliminary design.

14.4.3.2  Design Dimensions

The following design dimensions were established:

• Width = 20 ft (6.1  m)

• Depth = 8 ft (2.4 m)

• Length =  100ft  (30 m)

• Spacing = 30 ft  (9.1  m)

• Sludge fill depth = 5 ft (1.5 m)

• Cover thickness = 4  ft (1,2 m)

Test trenches were then constructed  on the site and
operated under proposed conditions to ensure their ef-
fectiveness and practicality in a full-scale operation. The
test was successful and the design proceeded based on
the above dimensions.

14.4.3.3  Calculations

Based on the design data and dimensions stated pre-
viously, calculations  were performed  for each of the
proposed monofills. Determinations made on the opera-
tion included:

• Trench capacity =  375 yd3 (287 m3)

• Number of trenches = 20

• Site  capacity == 7,500 yd3 (5,734 m3)

• Sludge volume received = 1.03 yd3/day (0.79 m3/day)

• Site  life = 20 years

14.4.3.4  Operational Procedures

Site preparation, on-going operations, and site comple-
tion consist of the following procedures:

1.  Twice each year a contractor is employed to exca-
   vate sufficient trench capacity for a 6-month sludge
   quantity.  The contractor  uses a single  front-end
   loader to excavate each 20-ft (6.1-m) wide trench to
   a depth of 8 ft (2.4 m). Excavated soil is stockpiled
   above and along both sides of the trench.

2.  A liner (60 mil HOPE) is installed in each trench, with
   a leachate collection system placed atop it.

3.  Once ready for operations, 6 months accumulation of
   sludge is  removed from sand drying beds and loaded
   on a dump truck owned by the treatment plant.

4.  The sludge is hauled the short distance to the trench-
   ing area.  At that location, dump trucks back into the
   trenches  from the open end of  the  trenches and
   deposit the sludge in 3- to 4-ft (0.9- to 1.2-m) high piles.
                                                  248

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5. A bulldozer carefully enters the trench intermittently
   to push the sludge into a 5-ft (1.5-m) high accumu-
   lation.

6. After each trench is filled to completion, the bulldozer
   is employed to spread cover over the 20-ft (6.1-m)
   wide trench from the soil stockpiles located on either
   side. The cover is spread in  a 4-ft (1.2-m) thick
   application to 1 ft (0.3 m) above grade.

7. The completed trench is then seeded to promote the
   growth of grasses.

8. Usually settlement of the trenches will not be severe
   due to the high solids content of the sludge and the
   cover thickness. Once each year the bulldozer em-
   ployed for landfilling operations is used  to  regrade
   completed trenches from the previous year. These
   trenches are then reseeded.

Table 14-8. Estimate of Total Annual Cost for Example Number 3
14.4.3.5   Cost Estimates

The cost estimate prepared for this operation is pre-
sented in Table 14-8. As shown, the total cost is com-
puted  at  $18,345  per year.  Considering a  sludge
quantity of 379 wet tons per year (344 Mg per year), this
equates to $48.40 per wet ton ($53.36  per Mg). This
represents a savings of $11.60 per wet ton ($12.79 per
Mg) when compared with the fee being charged by the
local MSW landfill. Accordingly, plant operators will initi-
ate the monofill disposal operation.

It should be noted that costs as low as $48.40 per wet
ton ($53.36  per Mg) cannot be achieved by most treat-
ment plants of this size. One of the reasons the cost is
low in this case is because this plant is able to monofill
6 months of sludge in 1 or 2 days. Under these circum-
stances, this facility is able to achieve  economies-pf-
scale usually found only at very large monofills.
Item
Mobilization
Loader
Dozer
Trench Excavation
Covering
Regrading
Seeding
Total
Quantity
2/ea
2/ea
600 cu yd
230 cu yd
1 acre
1 acre

Unit Cost
500 /ea
500 /ea
$2.50 /cu yd
$1.50/cuyd
$10.000 /acre
$4.500 /acre


$1.000
1,000
1.500
345
10,000
4.500
18,345
                                                   249

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                                            Chapter 15
                                          Case Studies
These case studies were obtained from discussions
with a number of state and regional authorities respon-
sible for sludge management. They illustrate a range of
surface disposal  activities being conducted throughout
the United States. Activities covered include surface
disposal of sewage sludge in a monofill, at a dedicated
disposal site, and at a dedicated beneficial use site,
in addition to sludge storage in lagoons prior to final
disposal.

15.1  Case Study 1: Surface Disposal in a
       Monofill Following Freeze-Thaw
       Conditioning in a Lagoon
       Impoundment

Anderson Septage Lagoon
Department of Public Works
Anderson, Alaska

 15.1.1  General Site Information

The City  of Anderson, about 75  miles  southwest of
Fairbanks, operates a lagoon impoundment for condi-
tioning domestic septage, of which  it receives about
400,000 gallons  annually. In 1994, the city of 700 ap-
plied to the Alaska Department of Environmental Con-
servation  (ADEC) for a permit to dispose of sludge
recovered from  its two storage lagoons in an onsite
monofill.
The permit application seeks an exemption from 40 CFR
 Part 503 pollutant limit for sludge disposed within 25 m
of a disposal site's boundary because Anderson's dis-
 posal unit is about 9 m (i.e.,  30 ft) from the site's north
 boundary (Figure 15-1). (If "site-specific" limits are  not
 set by the permitting authority, an alternative for disposal
 will have to be found.) Testing has determined that the
 city's sludge meets the pollution limits for solids that can
 be disposed of  at least 150 m from a  site's  nearest
 boundary.

 The domestic septage lagoon is located in a relatively
 remote area north of a U.S. Air Force landing strip and
 about 3 miles southeast of the Anderson (Figure 15-2).
 Moreover, the lagoon is restricted from  receiving any
 hazardous or industrial waste or  any municipal solid
waste. All waste received at the lagoon must meet toxic
characteristics leaching potential (TCLP) standards.

15.1.2   Site Characteristics

The Anderson lagoon is situated on a formation of gla-
cial outwash and alluvial sediment estimated to extend
to a depth of more than 20 ft, based on excavations in
a nearby gravel quarry. The sediment has been classi-
fied as poorly graded sand mixed with silt and gravel, a
geological material commonly referred to as pit run. The
site's top layer of silt loam, which was removed during
lagoon construction to take advantage of the frost-resis-
tant characteristic of the sediment, was stockpiled on
site for later use as a cover material.

Flood potential at the  site has been deemed minimal,
given average annual  precipitation  of only 12.7 in. In-
deed, no flooding occurred in Anderson during August
of 1967 when the region's heaviest rainfall  on record
(4.6  in.) caused  localized flood-water  problems. Al-
though Anderson did experience flooding in 1978 during
an unusually rapid thaw, it is believed that the lagoon,
which was not operating at the time, would not have
been affected.
The ground-water level at the site typically is more than
6 ft below the lagoon's percolation cell. Even during the
summer of  1992, when,ground water throughout the
region rose to an unusually high level, the water table at
the site was more than 4 ft below the percolation cell.
Further,  based in part on a 1983 engineering study,
ground water flows  from the lagoon impoundment in a
north by northeast  direction and generally away from
Anderson (see Figure  15-2).

 15.1.3  Domestic Septage Conditioning and
         Disposal

 15.1.3.1  Lagoon  Design

The Anderson domestic septage treatment works con-
 sists of a facultative cell flanked to the east and west by
 active primary lagoon cells and to the south by a third
 primary cell that is no longer in use. Adjoining the facul-
 tative cell to the north is a percolation cell, and beyond
 that  the sludge disposal  cell (see Figure 15-1). The
                                                  251

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                 no      to
                                                          •f'VTt ซiaoi'Intel
, 	
1 	 Y V
| !._.... ' ' "' ' 	 	
SLUDGE DISPOSAL
1 • CELL
	 __ 	
Y 	 .

••v
1
1
                                                                 pmr KOAO
                                              ANDERSON SEPTAGE LAGfJON
                                                   SME  PLAN
                                                                                                          BASIS or ELCVATIOM
                                                                                                          ASSUMED IOO.OO Of' TO*
                                                                                                          OF AL. CAf* UOHUUCMT
                                                                          SOILS NOTES
                                                                        I. SOIL TฃปT ซT-J IYHCAL Of
                                                                          SOILS FOUNO M H'J -I AND* 2.
                                                                        I. KIC. RATE Or MllveuY SANO IS
                                                                           S MIW./WCH.
                                                   aUVCLLY 1ANO
                     TEST PIT
PERCOLATION
CELL FLOOR
Figure 15-1.   Anderson septage lagoon.
                                                             252

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                            IV
                   Direction Groundwitof Flow
                   DeiarminM by DBS EnginMn
                   •On-ซttป Wซw Supply Stud/. 1983
                                                                Estimated Direction
                                                                of Groundwater Flow
                                                                from Anderson Lagoon
                   	U
                                                              ANDERSON
                                                              LAGOON
   OlrKtlon
17  GroundwmUr Flow
   at Gravel Quarry
Figure 15-2.  Site map of Anderson septage lagoon.

disposal cell (i.e., active sewage sludge unit) measures
90 x 200 ft in area and is surrounded by a 5-ft berm.

The lagoon cells measure 140 x 43 .ft (6,000 sq ft) in
area and 5.5 ft in depth to the top of the drain bed. Cell
holding capacity is 450,000 gallons of liquid and 13,000
cu ft of sludge (at a depth of 2 ft). Cells are lined with a
low-temperature arctic polyvinyl chloride (LTA PVC) ma-
terial,  which  provides  an impermeable barrier.  At the
bottom of each cell is a perforated high-density polyeth-
ylene (HOPE) pipe (10 ft on center) covered by 24 in. of
sandy gravel, allowing the cell to function as a reverse
drain field.

At the end of a storage period, liquid is siphoned off to
the facultative cell. When initial transfer of liquid is car-
ried out in the fall, a siphon alone is used because the
liquid  level is relatively high.  In the spring, after freeze-
thaw conditioning of the sludge has taken place and the
liquid  level is lower, a pump is used to prime the siphon;
a pump manifold was constructed for this purpose.

The disposal cell is lined with pit run, which is separated
from an 8-inch layer of silt by a geomembrane material.
The  gravelly layer functions as a French drain, with
 rainwater and snowmelt filtering through to the silt layer.
 From there the leachate drains into the percolation cell
 for gradual discharge to the ground through 6 in. of silt.
                    15.1.3.2   Conditioning and Disposal Process

                    The east and west primary cells receive domestic sep-
                    tage in alternating years. In the sprihg, at the end of a
                    receiving year, liquid is siphoned off from the lagoon cell
                    into the facultative cell, leaving only enough  residual
                    liquid to  saturate the accumulated sludge (maximum
                    liquid depth is 2 ft). The following spring, after the sludge
                    has  been conditioned through freezing  and thawing,
                    supernatant is siphoned off into the facultative cell. The
                    sludge is then left to  dry for about a week before it is
                    moved to the disposal cell—using a bulldozer and dump
                    truck—where it is spread onto a 6-inch layer of .silt loam.

                    Atypical  load of dewatered sludge is spread against the
                    berm and across a 20- x 30-ft area in a 2- to 3-ft layer,
                    and the edge of the sludge pile is finished at no  more
                    than a 2:1 slope. To "encapsulate" the material so that
                    pathogens and vector attraction are controlled, a 6-inch
                    layer of loam is spread on top of the sludge followed by
                    a layer of pit run. Once the cover is in place, the sludge
                    pile is seeded, and then reseeded in the  fall.

                    The ground cover that results from seeding the sludge
                    pile contributes to leachate control through transpiration
                    of rain water and snowmelt, while the loam cover re-
                    duces infiltration of water into the disposed sludge. The
                    purpose of the pit-run  layer/is to minimize erosional
                                                    253

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 effects that can be caused by the harsh climate. None-
 theless, some  liquid will inevitably reach the sludge
 layer. Thus, the base layer of loam and the percolation
 cell are intended to slow the discharge of leachate to
 the ground water to reduce concentrations of residual
 pollutants.
                       !!•
 15.1.4  Operations Factors

 15.1.4.1   Sludge Characteristics

 The City of Anderson has applied for a permit that would
 allow disposal of sludge within 25  m of the treatment
 works' north boundary with the following maximum pol-
 lutant concentrations:
 Arsenic
 Chromium
 Nickel
73 mg/dry kg

600 mg/dry kg

420 mg/dry kg
 Under part 503, these concentrations are acceptable
 only for sludge placed in an active sewage sludge unit
 whose boundary is 150 meters from the surface disposal
 site property line. The city seeks "site-specific" pollutant
 limits, arguing that, despite the close proximity of the
 treatment works' border, minimal opportunity exists for
 humans or wildlife to come within 150 m of the disposal
 cell. The area is not accessible to humans except on
 foot, and it does not include any intermittent creek bot-
 toms that might draw wildlife as well as hunters.

 Additionally, when  the city  tested its sludge for
 TCLP, results  indicated that pollutants  are  below
 regulatory levels.

 15.1.4.2   Monitoring

 In the spring, after freeze-thaw conditioning and transfer
 of supernatant and prior to disposal, sludge being held
 in a lagoon cell will be tested to determine if it meets
 permit requirements. Sludge will be analyzed for the
 parameters  listed in  Table  15-1. Testing will be per-
formed on a composite sample made up of three grab
samples, two collected from the base of the freeze-thaw

Table 15-1.  Sludge Monitoring Parameters
tararottw | units
Antric
Chromium
Nickd
Total Sends
Pwctrt Solid*
Toul VotttI* Solids
FwalCollfonn
mg/dry kg
mg/dfy kg
mg/dry kg
mg/l
%
%
#/dry gram
method
EPA 7060
EPA 7191
EPA 6010
SM' or EPA 160.3
SM or EPA 160.3
SM or EPA 160.4
MPN. SM 9222C
  bed bumper, opposite each domestic septage discharge
  culvert, and a third from the area of the culvert most
  used during the year (i.e., where the sludge is deepest).
  After collection and mixing, the sample will be iced and
  delivered to the testing lab within 1 day.

  The city has no plans to monitor ground water for nitrate.
  Therefore,  under part 503 the city will  be required to
  obtain a certification by a ground-water scientist that
  ground water will not be contaminated by the placement
  of sewage sludge on the active sewage sludge unit.
  During storage,  lagoon  cell  liners will prevent nitrate
  from leaching out of sludge. Once disposed, ammonia in
  the sludge will not be able to oxidize into nitrate because
  the disposal cell provides an  anaerobic environment.

  All records  concerning disposed sludge will be retained
  for 5 years.

  15.1.5  Disposal Cell Capacity

 The city estimates the site life of the disposal cell to be
 20 years. This estimate assumes that 2,700 cu ft (100
 yards) of sludge will be disposed each year. The as-
 sumption takes into account the 6 in. of silt that will be
 used to cover each year's load of sludge.

 15.2 Case Study 2: Use of a Lagoon for
       Sewage Sludge Storage Prior to
       Final Disposal (Lagoon
       Impoundment in Clayey Soils)
 Sludge Lagoon
 Domestic and Industrial Wastewater Treatment Facility
 Forest, Mississippi

 15.2.1  General Site Information

 In 1991, the City of Forest expanded and renovated  its
 domestic and industrial wastewater treatment works to
 increase its  liquid processing capabilities. As expected,
 given the increased effectiveness of improved opera-
 tions, the sludge  lagoon system soon approached  its
 solids holding capacity. Thus, the city has submitted an
 application for a permit to construct two additional stor-
 age  lagoon cells occupying about 5 acres.

 The city's sludge handling process consists of treatment
 in aerobic digesters, followed by thickening and storage
 in a  lagoon  impoundment. During storage, the sewage
 sludge undergoes final disinfection, stabilization, and
 thickening in anticipation of final disposal.

 Since  the  Forest  mechanical-biological  wastewater
treatment works went into operation northeast of the city
 in 1977, the area set aside for lagoon impoundments
has been expanded from 1.75 to 3.5 acres. The site of
the proposed additional lagoon cells is a 52-acre parcel
of open pastureland abutting two of the treatment works'
existing lagoons (Figure 15-3)."Because  the parcel  is
                                                 254

-------
   bounded to the north by a free-flowing stream and to the
   east and south by a  similar stream, a portion of its
   boundary is  characterized by wetland-type soils and
   vegetation; additionally, the land is considered to be in
   a 100-year flood zone. Nonetheless, a Phase I environ-
   mental site assessment concluded that no adverse rec-
   ognized environmental conditions are present on the
   property and that any potential impacts to the surround-
   ing properties related to lagoon construction  can be
   minimized or appropriately mitigated.


    75.2.2   Design Criteria

    Data gathering for a geotechnical investigation of  the
    site included 10 soil borings (see Figure 15-3), which
    found that near-surface soils in various locations con-
    sisted  of expansive clays containing pockets of silty
    clays and sandy clays and silty clays that extend from
    the ground surface to depths that ranged from about 5
    to 12 ft (Table 15-2). Underlying soils  included sandy
    clays that extended to depths that ranged from about 13
    to 16 ft as well as clays of the Yazoo Formation. Based
    on these findings, the geotechnical investigation con-
    cluded that the proposed lagoons could be constructed
    on the naturally deposited clay soils after proper site
    preparation (e.g., clearing, grubbing, and stripping of all
    organics). The investigation further concluded that the
    near-surface silty clay and clay soils could be used for
    embankment materials—although they are not the pre-
    ferred materials for this purpose—providing special de-
     sign  and  construction  measures  are  adopted.  For
     instance, the report recommended (1) the use of chemi-
     cal stabilization of onsite soils to reduce plasticity and,
     improve workability, and (2) the testing of each lift of fill
     material to provide some assurance that adequate and
     uniform densities are being obtained.

     Tests to determine the permeability of in-place soils at
     the  site—a characteristic that is critical to the location,
     design,  and proper functioning of a sewage sludge la-
     goon—found seepage values to be well below the maxi-

     Table 15-2.  Laboratory Permeability Test Results
                                       mum allowable rate of 500 gallons per day per acre
                                       required by state regulations.
                                       Concerning ground-water considerations, based on two
                                       soil borings that found free ground water at depths rang-
                                       ing from 8 to 13 ft, the geotechnical report concluded
                                       that problems might be encountered if construction ex-
                                       cavations exceed depths of about 7 ft. Additionally, the
                                       report recommended that excavations should achieve
                                       slopes no steeper than 5  horizontal to 1 vertical  to
                                       prevent the development of slough  sides.

                                        15.2.3  Sludge Collection and Disposal

                                        15.2.3.1   Sludge-Collection Process Steps

                                        The treatment works' impoundment lagoons receive
                                        sewage sludge from both industrial and domestic waste-
                                        water treatment streams. In the industrial stream, solids
                                        are collected in the following process steps:
                                        • Anaerobic Lagoons: Influent raw  wastewater is  re-
                                          ceived and primary removal of solids plus anaerobic
                                          decomposition of carbonaceous  biological oxygen
                                          demand take place, with solids settling to the bottom
                                          and accumulating over time.
                                        • Aerated Stabilization Basins (ASBs). A pair of basins
                                          serve as  complete-mix and partial-mix lagoons. Fol-
                                          lowing  significant decomposition  of sludge through
                                          anaerobic and aerobic processes during residence in
                                          the partial-mix lagpon,  floor drains and mechanical
                                           mixing  capability allow for periodic removal of solids.
                                           If adequate  digestion has occurred in the ASB,  the
                                           solids can be transferred directly to storage lagoons.

                                         • Sequencing Batch Reactors (SBRs).  Effluent from
                                           the ASBs is pumped to the SBRs, where the waste
                                           undergoes an anoxic treatment promoting denitrifica-
                                           tion followed by an aerobic treatment including nitri-
                                           fication.  The final phase of the  batch  treatment
                                           process involves settling and decanting, before solids
                                           are removed for mixing with other sludges.
                                            Laboratory Permeability Test Results
         Boring
          No.
Depth
 (ft)
  Soil
  Type
                                      Moisture
                                       Content
         In-Place
         Dry Unit
         Weight
          (pcf)
          Liquid
          Limit
       Plasticity
        Limit
       Plasticity
        Index
         Percent
       Passing the
         No. 200
        Sieve (%)
          (cm/sec)
           2
           2
           3
           8
           8
           9
 8-10
 13-15
 8-10
 8-10
 13-15
 8-10
  Clay
  Clay
Silty Clay
Silty Clay
Sandy Clay
Silty Clay
25.1
24.8
22.7
32.4
19.4
20.4
98.1
94.8
105.5
99.7
105.9
102.5
53
69
49
48
49
46
17
19
11
15
11
13
36
50
38
33
38
33
84.8
89.2
76.8
69.5
55.1
68.3
2.98X10"1
l.OOxlO4
1.25x10*
1.27x10-*
1.08x10-*
6.50x10-*
_
                                                         255

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In the domestic stream, solids are collected in the fol-
lowing process steps:

• Primary Clarifiers.  After screening  and degritting
  treatment, domestic flows are introduced to the pri-
  mary clarifier, where sludge  is collected by chain and
  flight in  rectangular basins. From  there, solids are
delivered by telescoping valves to a sewage sludge
pump wetwell.

First-Stage Clarifiers.  Effluent  from the  first-stage
aeration basins is received by 12 clarifier basins that
remove the settled solids using airlift pumping units.
A portion of the sludge is returned to first-stage aera-
                                              Boring Locations
                                           Scale:  1  in.  =  200 ft
                'SoSlesl'uigEfKjinetfs.lnc.


Figure 15-3.  Site of proposed lagoon cells (Geotechnical Investigation Report),
                   Note: Drawing provided
                   by Waggoneer Engineers,
                   Inc.
                                                   256

-------
  tion as  return-activated sludge  and the remainder
  gravity flows to the wetwell as waste-activated sludge.

• Second-Stage Clarifiers. The second-stage aeration
  basin is followed by  second-stage clarifiers, from
  which collected solids gravity flow to the second-
  stage return sludge pump wetwell. From there, the
  waste material is conveyed by lift pumps to a splitter
  box that diverts a portion of the sludge to the wetwell
  as waste-activated sludge.

Aerobic digesters receive all waste-activated sludge,
with the exception of sludge from the anaerobic lagoon
and from the ASB.
The two  existing sludge lagoons have a  total storage
capacity of 1.2 million cu ft. One of the cells reached its
capacity a number of years ago, while the other reached
its capacity only recently. Cells were loaded at a rate of 17
pounds of volatile suspended solids per 1,000 sq ft per day,
a rate that is well within the generally acceptable range.

15.2.3.2   Sludge-Disposal Alternatives

Operators of  the Forest treatment works recognize that
the Part  503 regulation makes disposal of sewage
sludge an entirely different issue  than storage.  Given
their immediate need for additional  storage capacity,
 however, they are deferring any decision on disposal
 alternatives for the time  being.

 Two possible approaches for final  disposal of the treat-
 ment works' sewage sludge  include land application and
 placement in an MSW landfill. Land  application would
 appear to be a less-attractive alternative because the
 sludge would need to meet specific  Part 503 require-
 ments that include limiting pathogens and metals.  In
 contrast, landfilling would primarily require the sludge
 to be sufficiently dewatered. Operators recognize that
 disposing sewage sludges in MSW landfills, as required,
 has  become significantly  more  expensive  in  recent
 years due to constraints on  capacity. Nonetheless, a
 nearby, privately owned MSW landfill that was recently
 permitted might present a reasonably cost-effective dis-
 posal option for the Forest treatment works.

 For the present, however, operators plan to expand their
 lagooning operation for storage of sludge  in anticipation
 of eventual  disposal. During  storage in the lagoons,
 sewage sludge organics are gradually stabilized through
 aerobic and anaerobic processes, and  the stabilized
 solids eventually settle to the bottom of the lagoon and
 accumulate.
  Clayey  soils that  predominate at the treatment works
  site are conducive to providing a barrier  of low  perme-
  ability soils  against  ground-water contamination.  As-
  suming  that an  active sewage  sludge lagoon  can
  effectively receive digested sludge and discharge a sol-
  ids-free supernatant until the average solids concentra-
tion is 8 percent for the entire lagoon volume, the rate
of waste sludge lagoon utilization will be approximately
1 acre per year for about the next 20 years.

If sewage sludge is stored on land (e.g., in a lagoon) for
longer than 2 years, the person who prepares the sew-
age sludge must demonstrate to the permitting authority
that the site is not an active sewage sludge unit. This
includes an explanation of why sewage sludge needs to
remain on the land for longer than 2  years prior to
disposal and a projection of when the sludge finally will
be used or disposed of. The surface disposal provisions
of the Part 503 rule do not apply when sewage sludge
is treated in a lagoon and treatment could be for an
indefinite period.

 15.2.4  Sludge Production Projections

Based on operating data, findings from  a facility study,
and the treatment works' long-term plan, operators have
estimated quantities of sewage sludge that will be pro-
duced by the year 2005 (Table  15-3). For  example,
operators project that sewage sludge produced by ASBs
for removal  to lagoons will reach 4,097 pounds per day;
this amount is calculated to decompose to about 2,538
 pounds per day. Similarly, sludge produced by SRBs is
 expected to reach about 1,738 pounds per day.

 In contrast, sewage sludge produced  from domestic
 flows is  expected to increase  at the moderate annual
 rate of 1.5 percent, based on current population trends.

 15.3  Case Study 3:  Dedicated Surface
       Disposal in a Dry-Weather Climate

 Solids Handling and Disposal Facility
 Domestic Wastewater Treatment Facility
 Colorado Springs,  Colorado

 15.3.1   General Site Information

 The City of Colorado Springs operates processes for
 managing and disposing of sewage sludge generated at
 its POTW, which treats average flows of over 34 million
 gallons per day. Along with an anaerobic digestion com-
 plex for stabilization and  an expanse of  facultative
 sludge basins for additional long-term treatment of sta-
 bilized material,  sewage sludge is  disposed of on a
 dedicated surface disposal site.

 The surface disposal site is located 18 miles south of
 the POTW at the  city's  Hanna Ranch property, which
 also is used for disposal of ash from the city's Ray Nixon
  Power Plant. A blend of  primary and secondary sludge
  is conveyed from the POTW to  Hanna Ranch via a
  pipeline—one of the longest pipelines in the country
  used  to transport sewage sludge.
  Minimal  residential and commercial development has
  taken place near the Hanna Ranch site due to a limited
                                                   257

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 Table 15-3.  Sewage Sludge Projections

Solids
Category
ASB FSS (#/day)
ASB nVSS (#/day)
ASB VSS (#/day)
ASB TOTALS
SBR FSS (#/day)
SBR nVSS (#/day)
SBR VSS (#/day)
SBR TOTALS
DOM. PLANT FSS (#/day)
DOM PLANT nVSS (#/day)
DOM. PLANT VSS (#/day)
DOM. TOTALS
TOTAL FSS (*/day)
TOTAL nVSS (*/day)
TOTAL VSS (#/day)
TOTAL SLUDGE SOUDS
1995
Digester
Influent
_ „
—
—
—
481
695
561
1.737
170
320
361
851
651
1,015
922
2.588
Lagoon
Influent
578
817
1,391
2,786
481
626
413
1,520
170
204
238
612
1,229
1,647
2,042
4,918
Final
Disposal
578
817
696
2.091
481
626
306
1.413
170
204
95
469
1,229
1,647
1,097
3,973
2005
Digester
Influent

	
—
—
757
1,095
923
2,775
197
371
419
987
955
1,466
1,342
3.762
Lagoon
Influent
730
1,021
2,346
4,097
757
985
641
2,383
197
237
276
710
1,684
2,243
3,263
7.190
Final
Disposal
730
1,021
782
2,533
757
985
475
2,217
197
237
110
544
1,684
2.243
1,367
5.294
 drinking water supply and the proximity of a military
 training range to the west. Given its relatively remote
 character, a portion of the ranch is set aside as  a wildlife
 area, which  is managed cooperatively by the state's
 Division of Wildlife and city  utilities.  Beyond merely
 monitoring the compatibility of operations with area
 wildlife, site managers have tested a habitat enhance-
 ment practice that involves growing feed crops within
 the disposal site for incidental grazing by antelope and
 waterfowl.

 The soils at the  Hanna Ranch site consist of verdos
 alluvium, piney creek alluvium, and a weather Pieere
 shale with low to very low permeabilities. Monthly aver-
 age temperatures at the site range from 29ฐF to 71 ฐF.

 Public access to  the surface disposal site is restricted
 by  a fence that  surrounds the  Hanna Ranch and a
 uniformed security guard stationed 24 hours a day at the
 north entrance. Visitors are allowed limited access to the
 ranch for hunting  and wildlife observation through a 3-ft
 opening in the fence at the site's south entrance, which
 is about 1.5 miles east of the active disposal units.

The site meets all of the Part 503 requirements. Char-
acterization/management issues addressed in the site's
state/county Certification of Designation  include:
 • A survey by the state's Division of Wildlife found that
  the  disposal operations do  not  adversely affect  a
  threatened or endangered species.

 • Although no wetlands have  been delineated in ac-
  cordance with U.S. EPA or Corps of Engineers pro-
  cedures, active sewage sludge units appear to be
  adjacent to one  small  (0.1  to 0.2 acres), isolated
  wetland in a creek drainage. Although disturbance of
  this wetland would be permitted under the nationwide
  permit for headwaters and isolated areas, current ac-
  tivities do no disturb the wetland.

 • A site ground-water plan was recently rewritten  by  a
  qualified ground-water scientist to comply with 40
  CFR Part 503. The plan includes 2 years of quarterly
  monitoring  to determine ambient conditions,  as re-
  quired by the state,  with a focus on total inorganic
  nitrogen and organic carbon concentrations.

• Modifications have been made to small sections of
  the active sewage sludge unit that were estimated to
  be special  flood  hazard areas that would be inun-
  dated by a 100-year flood. Runoff from a creek drain-
  age  (up to a  1,000-year  flood)  is  contained for
  evaporation at a retention dam.

• A review of area geology confirmed that the surface
  disposal site is not in a seismic impact zone or in an
  unstable area.
                                                   258

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15.3.2  Surface Disposal Approach

15.3.2.1   Process Description

At the solids handling and  disposal facility,  sewage
sludge is gas mixed in four 1.5-million gallon anaerobic
digesters.   Once  stabilized,  the  waste  material  is
pumped to 30 acres of facultative sludge basins (FSBs,
known in  other states as facultative sludge lagoons)
where it is treated under a 5-ft water cap for at least 3
years. After the digested sludge is  removed from the
bottom of the basins using a dredge equipped with a
diesel-driven pump, they are conveyed through a float-
ing, flexible pipe to a wet well in the control building. The
sludge then is pumped from the wet well to a riser at
each dedicated surface disposal (DSD) unit. From the
riser, the  sludge  is loaded into the holding tank of a
Terragator, a sludge dispersal vehicle equipped with
flotation tires,  and injected into the subsurface of the
DSD units. The four DSD units at Hanna Ranch (Figure
15-4) total 180 acres.
The primary method of liquid disposal is through evapo-
ration. Excess liquid from  the facultative basins is
pumped to supernatant lagoons for additional treatment,
evaporation, and  disposal.
 In 1993, over 9,000 metric tons of sludge was disposed
 by subsurface injection at an average rate of 113 metric
tons per  hectare (124.3  tons per 2.5 acres).  Disposal
operations are limited to seasons when both the soil in
the DSD units and the surface  of the FSBs are not
frozen. In 1993, disposal operations were conducted
from March 16 to November 11.

15.3.2.2   Character of Sewage Sludge

The sludge produced at the POTW is of high quality.
When surface disposed, however, the boundary of DSD
units (i.e., active sewage sludge units) must be  more
than 100 m from the property line of the surface disposal
site because of slightly elevated chromium concentra-
tions (Table 15-4).

Steps  taken  to control pathogens and  reduce vector
attraction in the sewage sludge make the sludge appro-
priate  for surface disposal. Relatively high concentra-
tions of  helminth  ova, however, have  prevented the
sludge from meeting Class A criteria without significant
additional treatment. Because the sludge is injected into
the surface, further pathogen and vector reduction con-
trols are not required by Part 503. The City of Colorado
Springs has elected, however, to treat its sludge further.
Pathogen reduction is carried, out using high-rate an-
aerobic digestion to meet the requirements of a process
to significantly reduce  pathogens (PSRP). The process
 involves the anaerobic treatment of sludge for a specific
 mean cell residence time (MCRT) of about 20 days at a
 temperature  of 96.8ฐF (36ฐC). Raw solids  are fed
                                                       DIGESTER'- CO
                                                       ENERGY 'RECOVERY BUILDING
                                                          '   '

  Figure 15-4.  Topographic map of Hanna Ranch area.
                                                    259

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  Table 15-4.  1993 Sewage Sludge Monitoring Results

1093
0*te
March 18
Jtrch 23
Kareh 30
iprta
\plป >3 ป
*prป20
*prM27
.lay 4
<ซy 18

Junal
tunes
June IS
tana 22
June 20
July 2O
July 27

Mig 17
4ug24
*ug3t
3ซp14
Up 21
3ep2S
Oct2B
ov2


Anenfc
. "0*0




22







<2 0


<2,0

<2,0
<2,0
2B


Chromkjrn
mg/kg















290

280
310
210


mg/kg




192









Z. 	






Mercury
mg/kg




4.31
















Moly
mg/kg




15
















Nickel
mg/kg















190

190
210

Selenium
mg/kg




20















Zinc
mg/kg




2,070















Conform '
MPN/g
430,000
230,000
• 150,000
40.000
40,000
65,600
2.200
5,900
800 '
400
1,100

800
300
500
800
640
2,020
	 800
130
	 50
260
110
	 210
130


Helminth, ป/4 g
Observed * Viable





2,000

0,000
1.200
2,000



3,200
4,400
2,400
2,400












S34











Salmonella
MPN/g








<0.2











Enleitc
PFU/4 g









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Table 15-5.  PSRP Minimum Temperatures for Anaerobic
          Digestion
PSRP Minimum Temperatures for
Anaerobic Digestion
Mean Cell
Residence Time
(days)
15
16
17
18
19
20
21
22
23
24
25
Minimum
Temperature
(ฐC/ฐF)
35/95
35/95
34/93
34/93
34/93
33/91
33/91
33/91
32/90
32/90
32/90
 solids reduction is a function of temperature and MCRT
 in the anaerobic digestion system. Thus, the same op-
 erational considerations (discussed above) for pathogen
 control ensure vector attraction reduction. In  1993, for
 example, average volatile solids reduction at the Hanna
 Ranch facility was 59 percent, well above the standard
 of 38 percent.

 15.3.3  Operation and Maintenance

 The surface disposal site is attended 10 hours a day by
 a crew of nine. It is linked by computer and microwave
 communications to the POTW in Colorado Springs to
 enable remote monitoring when operators are not on site.

 15.4  Case Study 4: Dedicated Surface
        Disposal in a Temperate Climate

 Sludge Surface Disposal Site
 Metro Sanitary District
 Springfield, Illinois

  15.4.1  General Site Information

 The Metro Sanitary District in Springfield, Illinois, has
 operated two  sites for treatment and  subsequent sur-
 face disposal of sewage sludge since  1973. At the dis-
 trict's Spring Creek surface disposal site, located north
 of the city in the vicinity of Capital Airport and the state
 fairgrounds (Figure  15-5),  sludge is  disposed  on 80
 acres of land following anaerobic digestion. Sludge re-
 ceived at the smaller, Sugar Creek surface disposal site,
which is directly east of the city and roughly between
two interchanges of Interstate 55 (Figure 15-6), is sub-
jected to aerobic digestion before disposal on 30 acres.

In most years, livestock feed has  been grown on a
portion of one or both sites. Sludge is disposed only on
the areas that are  not cropped, which are alternated
each year. Additionally, broadleaf weed killer is applied
annually at both sites. The sites must meet the require-
ments for pathogen control and vector attraction control,
including site restrictions, under the Part 503 rule.

Although the district has grown corn exclusively since
the late 1980s, other feed crops have included alfalfa,
sorghum,  soybeans, and winter wheat. The  disposal
sites have been plowed and disked annually, except at
the Sugar  Creek surface disposal  site between 1978
and 1987 when the district cultivated bluegrass and
attempted to enter  the sod market. As a result of the
more stringent limits on nitrate in the Part 503 regulation,
the district is switching at both sites from corn to canary
grass, a hay crop that has higher nitrate requirements.

Samples from monitoring wells at the sites have shown
that nitrate levels in ground water tend to be elevated at
certain times of the year and during specific  weather
patterns. As a result, along with planning to change the
feed crop at the site, the district has applied to the state
environmental agency and the U.S. EPA for reclassifica-
tion of the  sites' ground water as Class II water. The
district has assured authorities that it will be able to meet
applicable state and federal requirements for the protec-
tion of  ground water.
 As a result of the pathogen control and vector attraction
 reduction requirements  in  Part 503, the district also
 plans to upgrade its aerobic treatment process at the
 Sugar  Creek site (as described in Section 15.4.3.2).

  15.4.2 Design Criteria

 The western section of the Spring Creek surface disposal
 site, which  began receiving sludge for disposal in Octo-
 ber 1973, meets applicable design criteria for sludge
 disposal based on  site features that include being:

 • Situated 200 feet from any water well and above the
   10-year flood plain.

 • Constructed with a slope of less than 5 percent (ex-
   cept for a small  section of the interior portion of the
   site).
  • Bordered by a shallow berm and a restricted asphalt
   roadway to contain  runoff.

  • Characterized by a tight clay soil.

  Important design features of the Spring Creek site's east-
  ern section, which was put into service in March  1980,
  include being:
                                                    261

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                    )<•/
Figure 15-5.  Spring Creek disposal site.
                                                           262

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Figure 15-6.  Sugar Creek disposal site.
                                                          263

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   • Situated 150 feet from any water well and 200 feet
     from any surface water.

   • Constructed with a slope of less than 5 percent.

   • Bordered by a berm (necessary because this section
     of the site  is in a flood plain).

   • Characterized by a sandy soil.

   The district's Sugar Creek surface disposal site, which
   has been in  use since  October 1973, meets design
   criteria for sludge disposal based on site features that
   include being:

   • Situated 150 feet from any water well and 200 feet
    from any surface water.

   • Constructed with a slope of less than 5 percent.
  • Characterized by a silty loam soil.

  The site includes a 10-acre lagoon to catch runoff in the
  event  of flooding. In the 20-plus years of operation,
  however, the  site  has not been subjected to a major
  flooding event.

  Additionally, both the Spring Creek and Sugar Creek
  surface disposal sites are 200 feet from either an occu-
  pied dwelling or a public roadway.

  15.4.3  Treatment and Surface Disposal
          Approach

  15.4.3.1   Spring Creek Surface Disposal Site
  Process Description. The  primary and waste-activated
 sludge received at the Spring Creek surface disposal
 site  undergoes primary anaerobic digestion, which in-
 volves  heating and mixing of the material, followed by
 treatment in secondary digesters. By operating three
 primary digesters and six secondary units, on average
 about 28,000 gallons of sludge are processed each day.
 Operators also have attempted thickening waste-acti-
 vated sludge in one of the six secondary digesters; one
 of the approaches included the use of a gravity-belt
 thickener.

 Following the digestion process, the sludge is either  (1)
 held  in  uncovered drying beds and spread on the sur-
 face  disposal site after dewatering, or (2) it is sprayed
 onto  the disposal site using fixed risers spaced 150 to
 200 feet apart.

 When spraying,  pairs  of risers  operate in sequence
 dispersing 40,000 gallons of sludge with 50 psi of pres-
 sure across the area within  their range. The edge of the
 spray pattern for the site's 92 risers is set at 110 to 180
 feet from the surface of nearby Spring Creek. To mini-
 mize  leaching  of sludge into ground water, the entire
 disposal site is  underdrained 6 to 9 feet below ground
with 4- and 6-inch perforated pipe that is laterally spaced
at 50 to 75 feet. Underdrains and forcemains are flushed
  after spraying, and collected sludge water is pumped to
  the effluent end of the primary treatment process.

  The surface disposal site's 55,000 square feet of drying
  beds generally are used only during the colder months
  of winter, when spraying cannot be carried out, or when
  the spraying system is shut down for maintenance.
  Sludge placed in the beds in winter is allowed to dry until
  fall of that year, when it is hauled to the eastern section
  of the disposal site for spreading. The drying beds  re-
  ceived  120,000 gallons of sludge in 1983 and almost
  600,000 gallons in 1987, the only years to date when
  the beds were used.

  Sludge residuals collected in the  bottom of the site's
  secondary digesters are periodically pumped, using
  centrifugal pumps, to one of the  disposal sites or is
  drawn by gravity to the drying beds. Water drained from
  the drying beds is pumped to the effluent end of the
  primary treatment works.

  Character of Sewage Sludge. Sludge produced at the
  Spring Creek surface disposal site generally has a total
  solids content of 4.7 percent, volatile content of 41.2
  percent, and a volatile acids concentration of 260 mg/L.
  Annual loading rates  at the disposal site for nitrogen,
  phosphorus, and various metals are listed in Table 15-6.

  15.4.3.2   Sugar Creek Surface Disposal Site

  Process  Description. The  waste-activated sludge and
 floating scum materials  (from secondary clarifiers) re-
 ceived at the Sugar Creek surface disposal site undergo
 staged treatment in a series of three aerobic digestion
 units.  By operating units with a combined capacity of
 over 222,000 cubic feet (i.e.,  about 74,000 cubic feet
 each), on averages about 25,000 gallons of sludge can
 be processed per day. On average 106,000 gallons of
 sludge (with a suspended solids content of about 8,000
 mg/L)  is sent to the digesters daily.

 Each  day,  or as  needed, the  digestion  system's
 airflow is shut down so that supernatant can be drawn
 into contact aeration  tanks, making room for sludge
 inputs. Occasionally, surface scum is also removed and
 disposed  along  with other sludge.  During the winter,

Table 15-6.  Annual Pollutant Loading Rates at the Spring
          Creek Facility
Parameter

Organic Nitrogen
Phosphorus
Lead
Zinc
Copper
Nickel
Cadmium
Manganese

                            ซ":.'           ฃฃS
                             io.a             22.7
                             41-3             87..0
                             24.8             52.3
                             o?i8             o^
                             28.1             59.3
?Tฐa5?nฅ Jปctฐr - 0.002 x 14.1 - o;0282 (Heปt)J
[Loading Factor - 0.002 x 29.7 - 0.0594 (Bast)]
                                                      Note: Average over 1983-1992.
                                                  264

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sludge or scum is occasionally added to digestion tanks
to control temperatures and ice formation.

Every 5 or 10 days, when the solids levels in the system
reach about 15,000 to 25,000 mg/Lor clear supernatant
is no longer present,  sludge is removed from the final
digestion unit. The sludge material is removed in incre-
ments of 205,000 gallons and pumped, using centrifugal
pumps, to the active sewage sludge unit. At the unit, the
sludge is sprayed onto the surface from 30 risers each
spaced about 200 feet apart. The spray system func-
tions and is configured much like the system used at the
Spring Creek site; it includes an underdrain system, and
flushed sludge water is recycled to the treatment tanks.
At this site,  however,  three risers operate in sequence,
spraying 205,000 gallons of sludge within their range.

The site also includes two drying beds,  covering 2,500
square feet, which to date operators have not needed to
use in the  sludge treatment process.  Operators are
considering the addition of a lime stabilization  stage,
however, as a final treatment step. Stabilization may be
required during the winter months, when biofogicaf ac-
tivity in the aerobic digesters slows, to  meet Part 503
requirements for pathogen control and vector attraction
reduction.

Character of Sewage Sludge. Sludge  treated at the
Sugar Creek site generally has a total solids content of
1.9 percent and volatile content of 50 percent. Annual
loading rates at the disposal site for nitrogen, phospho-
rus, and various metals are listed in Table 15-7.

Table 15-7. Annual Pollutant Loading Rates at the Sugar
          Creek Facility
 Parameter

 Organic Nitrogen
 Phosphorus
 Lซad
 Zinc
 Cpppar
 Nickel
 Cadmium
 Manganese
annual Loading - lbป/ปcrซ

         1957.0
         969.4
          21.2
          46.2
          21.7
           1.9
          0.43
          83,2
 (loading Factor - 0.002 x 24.3 - 0.0486)
 Note: Average over 1983-1992.
                                                     265

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                                           APPENDIX A
                                       Permit Application
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 treat-
ing domestic sewage" (TWTDS) (i.e., other persons 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 generated
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  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
   applicants 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.

  • Sludge-only (non-NPDES) facilities  that are not apply-
    ing for site-specific limits, and not otherwise required to
    submit a full permit application, had to submit limited
    screening information by February 19, 1994.
The permit application information that must be submit-
ted depends on the type of treatment works and which
sewage sludge disposal practices are employed by the
treatment works. Questions on permit applications should
be directed to the appropriate State and EPA Regional
Sewage Sludge Contacts listed in Appendix B.

Sludge-Only Facilities
The  limited screening  information submitted by  a
sludge-only facility typically will include the following:
• Facility name, contact person,  mailing  address,
  phone number, and location.
• Name and address of owner and/or operator.
• An indication of whether the facility is a POTW, pri-
  vately owned treatment works, federally owned treat-
   ment works, blending or treatment operation, surface
   disposal site, or sewage sludge incinerator.
 •  The  amount of sewage  sludge generated and re-
   ceived, 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 persons receiving the sewage
   sludge for further processing or for use or disposal.
 • Information on sites where the sewage sludge are
   used or disposed.

 Treatment Works Submitting Full Permit
 Applications
 A full permit application is much  more comprehensive
 than the limited screening information described above
 for  sludge-only facilities. A full permit application typi-
 cally will include the following information:

 General Information
 • Name, contact person, mailing address, phone num-
   ber, and location.
 • Name and address of owner and/or operator.
                                                   267

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  • An indication of whether the facility is a POTW, pri-
    vately owned treatment works, federally owned treat-
    ment works, blending or treatment operation, surface
    disposal site, or sewage sludge incinerator.

  • Whether the facility is a Class I sludge management
    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 use or disposal occurs
   on Native American lands.

 • A topographic map showing sewage  sludge use or
   disposal sites 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 person from
  whom  the sewage sludge was received,  and any
  treatment the sewage sludge have received.

 • Description of any treatment 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 person for
  further treatment, the amount provided, the name and
    address of the receiving person, and a description of
    any subsequent treatment.

  Information on Surface Disposal of Sewage
  Sludge (If Sewage Sludge Is Placed on a
  Surface Disposal Site)

  •  The amount  of sewage sludge placed  on surface
    disposal sites.

  •  The name, address, contact person, and permit num-
    ber^) for each surface disposal site,  regardless of
    whether the applicant is the owner/operator.

  In addition, the following inform